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Sample records for region reveals layered

  1. Conserved S-Layer-Associated Proteins Revealed by Exoproteomic Survey of S-Layer-Forming Lactobacilli

    Science.gov (United States)

    Johnson, Brant R.; Hymes, Jeffrey; Sanozky-Dawes, Rosemary; Henriksen, Emily DeCrescenzo

    2015-01-01

    The Lactobacillus acidophilus homology group comprises Gram-positive species that include L. acidophilus, L. helveticus, L. crispatus, L. amylovorus, L. gallinarum, L. delbrueckii subsp. bulgaricus, L. gasseri, and L. johnsonii. While these bacteria are closely related, they have varied ecological lifestyles as dairy and food fermenters, allochthonous probiotics, or autochthonous commensals of the host gastrointestinal tract. Bacterial cell surface components play a critical role in the molecular dialogue between bacteria and interaction signaling with the intestinal mucosa. Notably, the L. acidophilus complex is distinguished in two clades by the presence or absence of S-layers, which are semiporous crystalline arrays of self-assembling proteinaceous subunits found as the outermost layer of the bacterial cell wall. In this study, S-layer-associated proteins (SLAPs) in the exoproteomes of various S-layer-forming Lactobacillus species were proteomically identified, genomically compared, and transcriptionally analyzed. Four gene regions encoding six putative SLAPs were conserved in the S-layer-forming Lactobacillus species but not identified in the extracts of the closely related progenitor, L. delbrueckii subsp. bulgaricus, which does not produce an S-layer. Therefore, the presence or absence of an S-layer has a clear impact on the exoproteomic composition of Lactobacillus species. This proteomic complexity and differences in the cell surface properties between S-layer- and non-S-layer-forming lactobacilli reveal the potential for SLAPs to mediate intimate probiotic interactions and signaling with the host intestinal mucosa. PMID:26475115

  2. The boundary layers as the primary transport regions of the earth's magnetotail

    Science.gov (United States)

    Eastman, T. E.; Frank, L. A.; Huang, C. Y.

    1985-01-01

    A comprehensive survey of ISEE and IMP LEPEDEA plasma measurements in the earth's magnetotail reveals that the magnetospheric boundary layer and the plasma sheet boundary layer are the primary transport regions there. These plasma measurements also reveal various components of the plasma sheet, including the central plasma sheet and plasma sheet boundary layer. A significant new result reported here is that of cold- and hot-plasma components that are spatially co-present within the central plasma sheet. Such plasma components cannot be explained merely by temporal variations in spectra involving the entire plasma sheet. Contributions to a low temperature component of the plasma sheet enter directly from the boundary layer located along the magnetotail flanks. Field-aligned flows predominate within the plasma sheet boundary layer which is almost always present and is located near the high- and low-latitude border of the plasma sheet. The plasma sheet boundary layer comprises highly anisotropic ion distributions, including counter-streaming ion beams, that evolve into the hot, isotropic component of the plasma sheet. Tailward acceleration regions generate these ion beams with plasma input from the magnetospheric boundary layer. Antisunward-flowing ion beams, at E/q less than 1 kV and of ionospheric composition, are frequently observed in the plasma sheet boundary layer and in tail lobes. These ion beams are likely accelerated at low altitude over the polar cap and especially along auroral field lines.

  3. Investigation of the interface region between a porous silicon layer and a silicon substrate

    International Nuclear Information System (INIS)

    Lee, Ki-Won; Park, Dae-Kyu; Kim, Young-You; Shin, Hyun-Joon

    2005-01-01

    Atomic force microscopy (AFM) measurement and X-ray diffraction (XRD) analysis were performed to investigate the physical and structural characteristics of the interface region between a porous silicon layer and a silicon substrate. We discovered that, when anodization time was increased under a constant current density, the Si crystallites in the interface region became larger and formed different lattice parameters than observed in the porous silicon layer. Secondary ion mass spectrometry (SIMS) analysis also revealed that the Si was more concentrated in the interface region than in the porous silicon layer. These results were interpreted by the deficiency of the HF solution in reaching to the interface through the pores during the porous silicon formation

  4. Boundary layers as the primary transport regions of the earth's magnetotail

    International Nuclear Information System (INIS)

    Eastman, T.E.; Frank, L.A.; Huang, C.Y.

    1985-01-01

    A comprehensive survey of ISEE and IMP LEPEDEA plasma measurements in the earth's magnetotail reveals that the magnetospheric boundary layer and the plasma sheet boundary layer are the primary transport regions there. These plasma measurements also distinguish various components of the plasma sheet, including the central plasma sheet and plasma sheet boundary layer. A significant new result reported here is the existence of cold-and hot-plasma components that are spatially copresent within the central plasma sheet. Such plasma components cannot be explained merely by temporal variations in spectra involving the entire plasma sheet. Contributions to a low-temperature component of the plasma sheet enter directly from the boundary layer located along the magnetotail flanks. Field-aligned flows predominate within the plasma sheet boundary layer, which is almost always present and is located near the northern and southern border of the plasma sheet. The plasma sheet boundary layer comprises highly anisotropic ion distributions, including counteracting ion beams, that evolve into the hot, isotropic component of the plasma sheet

  5. Layered phenomena in the mesopause region

    Science.gov (United States)

    Plane, J. M. C.; Bailey, S. M.; Baumgarten, G.; Rapp, M.

    2015-05-01

    This special issue of the Journal of Atmospheric and Solar-Terrestrial Physics comprises a collection of papers which were mostly presented at the 11th Layered Phenomena in the Mesopause Region (LPMR) Workshop, held at the University of Leeds between 29th July 2013 and 1st August 2013. The topics covered at the workshop included atmospheric dynamics, mesospheric ice clouds, meteoric metal layers, meteoric smoke particles, and airglow layers. There was also a session on the potential of planned sub-orbital spacecraft for making measurements in the mesosphere and lower thermosphere (MLT).

  6. Preface to special issue: Layered Phenomena in the Mesopause Region

    Science.gov (United States)

    Chu, Xinzhao; Marsh, Daniel R.

    2017-09-01

    Historically, the Layered Phenomena in the Mesopause Region (LPMR) workshops have focused on studies of mesospheric clouds and their related science, including spectacular noctilucent clouds (NLCs), polar mesospheric clouds (PMCs), and polar mesospheric summer echoes (PMSEs). This is because, in the pre-technology era, these high-altitude ( 85 km) clouds revealed the existence of substance above the 'normal atmosphere' - our near-space environment is not empty! The occurrence and nature of these clouds have commanded the attention of atmospheric and space scientists for generations. Modern technologies developed in the last 50 years have enabled scientists to significantly advance our understanding of these layered phenomena. Satellite observations expanded these studies to global scales, while lidar and radar observations from the ground enabled fine-scale studies. The launch of the Aeronomy of Ice in the Mesosphere (AIM) satellite in 2007 brought mesospheric cloud research to a more mature level.

  7. The γ Dor stars as revealed by Kepler: A key to reveal deep-layer rotation in A and F stars

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    Salmon S. J. A. J.

    2017-01-01

    Full Text Available The γ Dor pulsating stars present high-order gravity modes, which make them important targets in the intermediate-and low-mass main-sequence region of the Hertzsprung-Russell diagram. Whilst we have only access to rotation in the envelope of the Sun, the g modes of γ Dor stars can in principle deliver us constraints on the inner layers. With the puzzling discovery of unexpectedly low rotation rates in the core of red giants, the γ Dor stars appear now as unique targets to explore internal angular momentum transport in the progenitors of red giants. Yet, the γ Dor pulsations remain hard to detect from the ground for their periods are close to 1 day. While the CoRoT space mission first revealed intriguing frequency spectra, the almost uninterrupted 4-year photometry from the Kepler mission eventually shed a new light on them. It revealed regularities in the spectra, expected to bear signature of physical processes, including rotation, in the shear layers close to the convective core. We present here the first results of our effort to derive exploitable seismic diagnosis for mid- to fast rotators among γ Dor stars. We confirm their potential to explore the rotation history of this early phase of stellar evolution.

  8. Boundary layer theory approach to the concentration layer adjacent to the ceiling wall of a hydrogen leakage: Axisymmetric impinging and far regions

    Energy Technology Data Exchange (ETDEWEB)

    El-Amin, M.F.; Kanayama, H. [Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan)

    2009-02-15

    As hydrogen leaks into a partially open space with a ceiling wall, a boundary layer of hydrogen can be constructed under that wall due to the impingement on the wall and the buoyancy force. The resulting boundary layer can be divided into two regions, namely the stagnation-point region and the far region. When the geometry of the source of the hydrogen leak is circular, such as a pinhole or an o-ring, the behavior of leakage flow will be axisymmetric due to the resulting radial jet. In contrast, when the geometry of the source of the hydrogen leak is planar, such as a crack, the behavior of leakage flow will be planar due to the resulting planar jet. Previously, we studied the planar case in the context of both the stagnation-point flow region [El-Amin MF, Kanayama H. Boundary layer theory approach to the concentration layer adjacent to a ceiling wall at impinging region of a hydrogen leakage. Int J Hydrogen Energy 2008; 33(21): 6393-00] and the far region [El-Amin MF, Inoue M, Kanayama H. Boundary layer theory approach to the concentration layer adjacent to a ceiling wall of a hydrogen leakage: far region. Int J Hydrogen Energy 2008; 33(24):7642-7]. This paper is concerned with both the stagnation-point flow region and the far region of the axisymmetric concentration boundary layer adjacent to a ceiling wall. Flow in the stagnation-point region is treated as Hiemenz flow, while it is treated as Blasius flow in the far region. The current results are compared with the planar cases [El-Amin MF, Kanayama H. Boundary layer theory approach to the concentration layer adjacent to a ceiling wall at impinging region of a hydrogen leakage. Int J Hydrogen Energy 2008; 33(21): 6393-00; El-Amin MF, Inoue M, Kanayama H. Boundary layer theory approach to the concentration layer adjacent to a ceiling wall of a hydrogen leakage: far region. Int J Hydrogen Energy 2008; 33(24):7642-7] for both stagnation-point flow and far regions. Both momentum and concentration boundary layer

  9. Statistical modeling of temperature, humidity and wind fields in the atmospheric boundary layer over the Siberian region

    Science.gov (United States)

    Lomakina, N. Ya.

    2017-11-01

    The work presents the results of the applied climatic division of the Siberian region into districts based on the methodology of objective classification of the atmospheric boundary layer climates by the "temperature-moisture-wind" complex realized with using the method of principal components and the special similarity criteria of average profiles and the eigen values of correlation matrices. On the territory of Siberia, it was identified 14 homogeneous regions for winter season and 10 regions were revealed for summer. The local statistical models were constructed for each region. These include vertical profiles of mean values, mean square deviations, and matrices of interlevel correlation of temperature, specific humidity, zonal and meridional wind velocity. The advantage of the obtained local statistical models over the regional models is shown.

  10. Structure of HIV-1 gp120 with gp41-interactive region reveals layered envelope architecture and basis of conformational mobility.

    Science.gov (United States)

    Pancera, Marie; Majeed, Shahzad; Ban, Yih-En Andrew; Chen, Lei; Huang, Chih-chin; Kong, Leopold; Kwon, Young Do; Stuckey, Jonathan; Zhou, Tongqing; Robinson, James E; Schief, William R; Sodroski, Joseph; Wyatt, Richard; Kwong, Peter D

    2010-01-19

    The viral spike of HIV-1 is composed of three gp120 envelope glycoproteins attached noncovalently to three gp41 transmembrane molecules. Viral entry is initiated by binding to the CD4 receptor on the cell surface, which induces large conformational changes in gp120. These changes not only provide a model for receptor-triggered entry, but affect spike sensitivity to drug- and antibody-mediated neutralization. Although some of the details of the CD4-induced conformational change have been visualized by crystal structures and cryoelectron tomograms, the critical gp41-interactive region of gp120 was missing from previous atomic-level characterizations. Here we determine the crystal structure of an HIV-1 gp120 core with intact gp41-interactive region in its CD4-bound state, compare this structure to unliganded and antibody-bound forms to identify structurally invariant and plastic components, and use ligand-oriented cryoelectron tomograms to define component mobility in the viral spike context. Newly defined gp120 elements proximal to the gp41 interface complete a 7-stranded beta-sandwich, which appeared invariant in conformation. Loop excursions emanating from the sandwich form three topologically separate--and structurally plastic--layers, topped off by the highly glycosylated gp120 outer domain. Crystal structures, cryoelectron tomograms, and interlayer chemistry were consistent with a mechanism in which the layers act as a shape-changing spacer, facilitating movement between outer domain and gp41-associated beta-sandwich and providing for conformational diversity used in immune evasion. A "layered" gp120 architecture thus allows movement among alternative glycoprotein conformations required for virus entry and immune evasion, whereas a beta-sandwich clamp maintains gp120-gp41 interaction and regulates gp41 transitions.

  11. The intermediate layers and associated tidal motions observed by a digisonde in the equatorial anomaly region

    Directory of Open Access Journals (Sweden)

    C.-C. Lee

    2003-04-01

    Full Text Available This investigation presents an initial attempt to analyze a full year of daily ionosonde observations relevant to the determination of plasma densities, tidal structures, and ion transports in the equatorial anomaly region of the lower ionosphere. Particular focus is on the intermediate layers, their seasonal and diurnal variations, and cause-effect relationships. The ionogram database was recorded using a digisonde portable sounder (DPS at National Central University (NCU, 24 °58' N, 121°11' E during 1996. Statistical results indicate that the intermediate layers appear primarily during the daytime of the spring/winter months. The monthly median height characteristics reveal that the layers descend from high to low altitudes and different tidal motions control the layers in different months. Generally, the semi-diurnal and quarter-diurnal tides, which cause ionization convergence, are mainly in the spring/winter and summer/autumn months, respectively. Variations in the electron densities of the layers also indicate that the density increases could result from a great number of molecular and metallic ions. Furthermore, a novel approach to ionogram presentation is introduced to investigate the intermediate layers. This approach allows the DPS to characterize the detailed daily information of the intermediate layers.Key words. Ionosphere (equatorial ionosphere; ionosphere-atmosphere interactions; ionospheric irregularities

  12. Complex (Nonstandard) Six-Layer Polytypes of Lizardite Revealed from Oblique-Texture Electron Diffraction Patterns

    International Nuclear Information System (INIS)

    Zhukhlistov, A.P.; Zinchuk, N.N.; Kotel'nikov, D.D.

    2004-01-01

    Association of simple (1T and 3R) and two complex (nonstandard) orthogonal polytypes of the serpentine mineral lizardite from the Catoca kimberlite pipe (West Africa) association is revealed from oblique-texture electron diffraction patterns. A six-layer polytype with an ordered superposition of equally oriented layers (notation 3 2 3 2 3 4 3 4 3 6 3 6 or ++ - -00) belonging to the structural group A and a three-layer (336 or I,I,II) or a six-layer (336366 or I,I,II,I,II,II) polytype with alternating oppositely oriented layers and semi-disordered structure are identified using polytype analysis

  13. Transforming the representation of the boundary layer and low clouds for high-resolution regional climate modeling: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hall, Alex [University of California, Los Angeles, CA (United States). Joint Institute for Regional Earth System Science and Engineering

    2013-07-24

    Stratocumulus and shallow cumulus clouds in subtropical oceanic regions (e.g., Southeast Pacific) cover thousands of square kilometers and play a key role in regulating global climate (e.g., Klein and Hartmann, 1993). Numerical modeling is an essential tool to study these clouds in regional and global systems, but the current generation of climate and weather models has difficulties in representing them in a realistic way (e.g., Siebesma et al., 2004; Stevens et al., 2007; Teixeira et al., 2011). While numerical models resolve the large-scale flow, subgrid-scale parameterizations are needed to estimate small-scale properties (e.g. boundary layer turbulence and convection, clouds, radiation), which have significant influence on the resolved scale due to the complex nonlinear nature of the atmosphere. To represent the contribution of these fine-scale processes to the resolved scale, climate models use various parameterizations, which are the main pieces in the model that contribute to the low clouds dynamics and therefore are the major sources of errors or approximations in their representation. In this project, we aim to 1) improve our understanding of the physical processes in thermal circulation and cloud formation, 2) examine the performance and sensitivity of various parameterizations in the regional weather model (Weather Research and Forecasting model; WRF), and 3) develop, implement, and evaluate the advanced boundary layer parameterization in the regional model to better represent stratocumulus, shallow cumulus, and their transition. Thus, this project includes three major corresponding studies. We find that the mean diurnal cycle is sensitive to model domain in ways that reveal the existence of different contributions originating from the Southeast Pacific land-masses. The experiments suggest that diurnal variations in circulations and thermal structures over this region are influenced by convection over the Peruvian sector of the Andes cordillera, while

  14. Age and gender estimation using Region-SIFT and multi-layered SVM

    Science.gov (United States)

    Kim, Hyunduk; Lee, Sang-Heon; Sohn, Myoung-Kyu; Hwang, Byunghun

    2018-04-01

    In this paper, we propose an age and gender estimation framework using the region-SIFT feature and multi-layered SVM classifier. The suggested framework entails three processes. The first step is landmark based face alignment. The second step is the feature extraction step. In this step, we introduce the region-SIFT feature extraction method based on facial landmarks. First, we define sub-regions of the face. We then extract SIFT features from each sub-region. In order to reduce the dimensions of features we employ a Principal Component Analysis (PCA) and a Linear Discriminant Analysis (LDA). Finally, we classify age and gender using a multi-layered Support Vector Machines (SVM) for efficient classification. Rather than performing gender estimation and age estimation independently, the use of the multi-layered SVM can improve the classification rate by constructing a classifier that estimate the age according to gender. Moreover, we collect a dataset of face images, called by DGIST_C, from the internet. A performance evaluation of proposed method was performed with the FERET database, CACD database, and DGIST_C database. The experimental results demonstrate that the proposed approach classifies age and performs gender estimation very efficiently and accurately.

  15. Quantitative Differentiation of LV Myocardium with and without Layer-Specific Fibrosis Using MRI in Hypertrophic Cardiomyopathy and Layer-Specific Strain TTE Analysis.

    Science.gov (United States)

    Funabashi, Nobusada; Takaoka, Hiroyuki; Ozawa, Koya; Kamata, Tomoko; Uehara, Masae; Komuro, Issei; Kobayashi, Yoshio

    2018-05-30

    To achieve further risk stratification in hypertrophic cardiomyopathy (HCM) patients, we localized and quantified layer-specific LVM fibrosis on MRI in HCM patients using regional layer-specific peak longitudinal strain (PLS) and peak circumferential strain (PCS) in LV myocardium (LVM) on speckle tracking transthoracic echocardiography (TTE). A total of 18 HCM patients (14 males; 58 ± 17 years) underwent 1.5T-MRI and TTE. PLS and PCS in each layer of the LVM (endocardium, epicardium, and whole-layer myocardium) were calculated for 17 AHA-defined lesions. MRI assessment showed that fibrosis was classified as endocardial, epicardial, or whole-layer (= either or both of these). Regional PLS was smaller in fibrotic endocardial lesions than in non-fibrotic endocardial lesions (P = 0.004). To detect LV endocardial lesions with fibrosis, ROC curves of regional PLS revealed an area under the curve (AUC) of 0.609 and a best cut-off point of 13.5%, with sensitivity of 65.3% and specificity of 54.3%. Regional PLS was also smaller in fibrotic epicardial lesions than in non-fibrotic epicardial lesions (P layer myocardium analysis, PLS was smaller in fibrotic lesions than in non-fibrotic lesions (P layer LV lesions with fibrosis, ROC curves of regional PLS revealed an AUC of 0.674 and a best cut-off point of 12.5%, with sensitivity of 79.0% and specificity of 50.7%. There were no significant differences in PCS of LV myocardium (endocardium, epicardium, and whole-layer) between fibrotic and non-fibrotic lesions. Quantitative regional PLS but not PCS in LV endocardium, epicardium, and whole-layer myocardium provides useful non-invasive information for layer-specific localization of fibrosis in HCM patients.

  16. EPA Region 1 - Map Layers for Valley ID Tool (Hosted Feature Service)

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Valley Service Feature Layer hosts spatial data for EPA Region 1's Valley Identification Tool. These layers contain attribute information added by EPA R1 GIS...

  17. Momentum transport process in the quasi self-similar region of free shear mixing layer

    Science.gov (United States)

    Takamure, K.; Ito, Y.; Sakai, Y.; Iwano, K.; Hayase, T.

    2018-01-01

    In this study, we performed a direct numerical simulation (DNS) of a spatially developing shear mixing layer covering both developing and developed regions. The aim of this study is to clarify the driving mechanism and the vortical structure of the partial counter-gradient momentum transport (CGMT) appearing in the quasi self-similar region. In the present DNS, the self-similarity is confirmed in x/L ≥ 0.67 (x/δU0 ≥ 137), where L and δU0 are the vertical length of the computational domain and the initial momentum thickness, respectively. However, the trend of CGMT is observed at around kδU = 0.075 and 0.15, where k is the wavenumber, δU is the normalized momentum thickness at x/L = 0.78 (x/δU0 = 160), and kδU = 0.075 corresponds to the distance between the vortical/stretching regions of the coherent structure. The budget analysis for the Reynolds shear stress reveals that it is caused by the pressure diffusion term at the off-central region and by -p (∂ u /∂ y ) ¯ in the pressure-strain correlation term at the central region. As the flow moves toward the downstream direction, the appearance of those terms becomes random and the unique trend of CGMT at the specific wavenumber bands disappears. Furthermore, we investigated the relationship between the CGMT and vorticity distribution in the vortex region of the mixing layer, in association with the spatial development. In the upstream location, the high-vorticity region appears in the boundary between the areas of gradient momentum transport and CGMT, although the high-vorticity region is not actively producing turbulence. The negative production area gradually spreads by flowing toward the downstream direction, and subsequently, the fluid mass with high-vorticity is transported from the forehead stretching region toward the counter-gradient direction. In this location, the velocity fluctuation in the high-vorticity region is large and turbulence is actively produced. In view of this, the trend of

  18. Wind tunnel study of the wind turbine interaction with a boundary-layer flow: Upwind region, turbine performance, and wake region

    Science.gov (United States)

    Bastankhah, M.; Porté-Agel, F.

    2017-06-01

    Comprehensive wind tunnel experiments were carried out to study the interaction of a turbulent boundary layer with a wind turbine operating under different tip-speed ratios and yaw angles. Force and power measurements were performed to characterize the variation of thrust force (both magnitude and direction) and generated power of the wind turbine under different operating conditions. Moreover, flow measurements, collected using high-resolution particle-image velocimetry as well as hot-wire anemometry, were employed to systematically study the flow in the upwind, near-wake, and far-wake regions. These measurements provide new insights into the effect of turbine operating conditions on flow characteristics in these regions. For the upwind region, the results show a strong lateral asymmetry under yawed conditions. For the near-wake region, the evolution of tip and root vortices was studied with the use of both instantaneous and phase-averaged vorticity fields. The results suggest that the vortex breakdown position cannot be determined based on phase-averaged statistics, particularly for tip vortices under turbulent inflow conditions. Moreover, the measurements in the near-wake region indicate a complex velocity distribution with a speed-up region in the wake center, especially for higher tip-speed ratios. In order to elucidate the meandering tendency of far wakes, particular focus was placed on studying the characteristics of large turbulent structures in the boundary layer and their interaction with wind turbines. Although these structures are elongated in the streamwise direction, their cross sections are found to have a size comparable to the rotor area, so that they can be affected by the presence of the turbine. In addition, the study of spatial coherence in turbine wakes reveals that any statistics based on streamwise velocity fluctuations cannot provide reliable information about the size of large turbulent structures in turbine wakes due to the effect of wake

  19. Atmospheric aerosol layers over Bangkok Metropolitan Region from CALIPSO observations

    Science.gov (United States)

    Bridhikitti, Arika

    2013-06-01

    Previous studies suggested that aerosol optical depth (AOD) from the Earth Observing System satellite retrievals could be used for inference of ground-level air quality in various locations. This application may be appropriate if pollution in elevated atmospheric layers is insignificant. This study investigated the significance of elevated air pollution layers over the Bangkok Metropolitan Region (BMR) from all available aerosol layer scenes taken from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) for years 2007 to 2011. The results show that biomass burning smoke layers alone were the most frequently observed. The smoke layers accounted for high AOD variations and increased AOD levels. In the dry seasons, the smoke layers alone with high AOD levels were likely brought to the BMR via northeasterly to easterly prevailing winds and found at altitudes above the typical BMR mixing heights of approximately 0.7 to 1.5 km. The smoke should be attributed to biomass burning emissions outside the BMR.

  20. Determination of regional heat fluxes from the growth of the mixed layer

    Energy Technology Data Exchange (ETDEWEB)

    Gryning, S.E. [Risoe National Lab., Roskilde (Denmark); Batchvarova, E. [National Inst. of Meteorology and Hydrology, Sofia (Bulgaria)

    1997-10-01

    The distribution of surface sensible heat flux is a critical factor in producing and modifying the mesoscale atmospheric flows, turbulence and evaporation. Parameterizations that assume homogeneous land characteristics are inappropriate to represent the spatial variability often found in nature. One possibility to overcome this problem is to increase the resolution of the model grid which demands unrealistic computing resources and data for model initialization. Area averaged fluxes can be obtained from aircraft measurements. It is essential that the flights are performed at a height where the individual surface features are not felt. A large number of flights and appropriate pattern to meet the task are needed in order to achieve a fair statistics. The mixed layer grows in response to the regional turbulent fluxes including the aggregation and small scale processes. The region of influence in upwind direction is typically 20 times the height of the mixed layer for convective and 100 times the height of the mixed layer for atmospheric near neutral conditions. In this study we determine the regional integrated sensible heat flux from information on the evolution of the mixed layer over the area. The required information to use the method can be derived from wind speed and temperature profiles obtained by radio-soundings when performed frequently enough to provide a reasonably detailed structure of the development of the mixed-layer. The method is applied to estimate the regional heat flux over the NOPEX experimental area for three days during the campaign in 1994. (au)

  1. Prevalence and pathology of oviduct impaction in commercial white leghorn layer chicken in Namakkal region of India

    Directory of Open Access Journals (Sweden)

    P. Srinivasan

    2014-08-01

    a pure culture in 29 birds and concurrent with other bacterial agents in 16 birds. Serotyping of E. coli isolates revealed that O144, O54 and O109 were the predominant types. Necropsy examination of carcasses with impacted oviduct showed emaciation, peritonitis, regression of ovarian follicles and distension of oviduct commonly in the infundibulum and magnum region. The exudate was either large mass with concentric layering on cut section or numerous caesous masses with varying size and shape often mixed with creamy or serosangunious fluid. Histopathological examination of oviduct revealed the presence of lymphoid foci in the epithelial layer with marked atrophy and degeneration of mucosal folds. Conclusions: Impacted oviduct constituted 0.87 % of oviduct abnormality in commercial layer chicken with an overall mortality of 0.5 %. The findings of this study showed that the oviduct impaction might be caused by E.coli in concurrence with Proteous spp., Klebsiella spp., Streptococcus spp. and Mycoplasma.

  2. Structural and functional characterization of EIAV gp45 fusion peptide proximal region and asparagine-rich layer

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Liangwei; Du, Jiansen [State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin 300071 (China); Wang, Xuefeng; Zhou, Jianhua; Wang, Xiaojun [State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001 (China); Liu, Xinqi, E-mail: liu2008@nankai.edu.cn [State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin 300071 (China)

    2016-04-15

    Equine infectious anaemia virus (EIAV) and human immunodeficiency virus (HIV) are members of the lentiviral genus. Similar to HIV gp41, EIAV gp45 is a fusogenic protein that mediates fusion between the viral particle and the host cell membrane. The crystal structure of gp45 reported reveals a different conformation in the here that includes the fusion peptide proximal region (FPPR) and neighboring asparagine-rich layer compared with previous HIV-1 gp41 structures. A complicated hydrogen-bond network containing a cluster of solvent molecules appears to be critical for the stability of the gp45 helical bundle. Interestingly, viral replication was relatively unaffected by site-directed mutagenesis of EIAV, in striking contrast to that of HIV-1. Based on these observations, we speculate that EIAV is more adaptable to emergent mutations, which might be important for the evolution of EIAV as a quasi-species, and could potentially contribute to the success of the EIAV vaccine. - Highlights: • The crystal structure of EIAV gp45 was determined. • The fusion peptide proximal region adopts a novel conformation different to HIV-1. • The asparagine-rich layer includes an extensive hydrogen-bond network. • These regions of EIAV are highly tolerant to mutations. • The results provide insight into the mechanism of gp41/gp45-mediated membrane fusion.

  3. Differential erosion and the formation of layered yardangs in the Loulan region (Lop Nur), eastern Tarim Basin

    Science.gov (United States)

    Lin, Yongchong; Xu, Lishuai; Mu, Guijin

    2018-02-01

    Yardangs are a type of wind-sculpted landform which generally form in hyper-arid regions. Several factors affect the development of yardangs, and the relative importance of these factors likely varies with differences in regional environmental factors. In the Loulan region of Lop Nur, wind dynamics are the principal factor affecting the development of yardangs. However, layered yardangs, which have undergone a unique form of differential erosion, are common in the region. These erosional landforms differ from typical yardangs which are eroded solely by abrasion and deflation. We conducted field and laboratory investigations of layered yardangs to determine their origin. The results indicate that there are two types of strata comprising the yardangs: uncompacted sand-silt layers, with a lower carbonate content; and compacted clay-silt layers, with a higher carbonate content. Both types of strata are horizontal and occur in alternating layers. This type of structure enables the wind to more easily erode the less resistant sand-silt layers at different heights, leaving the more resistant compacted clay-silt layers relatively intact. Eventually the undercut remnant clay-silt layers collapse once the weight of the suspended strata exceeds their elastic resistance (more than 90% of the fallen blocks have length/thickness ratios between 1.2 and 2.5). Therefore, in addition to wind dynamics, the lithology and structure of the strata are important factors affecting the development of the layered yardangs. This type of differential erosion accelerates the development of the yardangs in the Loulan region.

  4. An engineering inviscid-boundary layer method for calculation of aerodynamic heating in the leeward region

    International Nuclear Information System (INIS)

    Dirin, M.M.; Karimian, S.M.H.; Maerefat, M.

    2003-01-01

    An engineering method has been modified for the prediction of aerodynamic heating of the hypersonic bodies in the leeward region. This is achieved using our proposed new method for determining streamlines in the leeward region. The modified form of Maslen's second order relation, which calculates pressure in the shock layer explicitly, is employed. The inviscid outer flow within the shock layer is first solved. The calculated solution, then, is used to determine the flow properties at the boundary layer edge and the orientation of the surface streamlines. Boundary layer equations, written in the streamline coordinates, are integrated along the surface to obtain the rate of heat transferred to the body surface. The present method is an inverse method in which the body shape is obtained according to the shape of the shock. In general, inviscid-boundary layer engineering methods calculate accurately the orientation of streamlines in the windward side only, and therefore they are not usually applicable in the leeward region. In the present study, a new method is proposed to determine the orientation of the surface streamlines in the leeward region. Using the present method, three-dimensional hypersonic flow is solved fast and easy all around a cone. The obtained results show that the corrections presented in this study extend excellently the application of the method to the leeward region. (author)

  5. Micro-buckling of periodically layered composites in regions of stress concentration

    DEFF Research Database (Denmark)

    Poulios, Konstantinos; Niordson, Christian Frithiof

    2016-01-01

    -buckling related failure in regions of stress concentrations. A series of parametric studies show the effect of non-uniform stress distributions due to bending loads and the presence of geometrical features such as notches and holes on the initiation of micro-buckling. The contribution of the bending stiffness...... of the reinforcing layers on the resistance against micro-buckling introduces a dependence on the layer thickness, resulting in size-scale dependent strength limits. Therefore, both the shape and dimensions of the considered geometrical features and the layering thickness of the micro-structure are varied as part...... of the parametric studies. Moreover, the impact of imperfections in the composite micro-structure on the strength of the considered specimens is investigated....

  6. Investigation of radiative effects of the optically thick dust layer over the Indian tropical region

    Directory of Open Access Journals (Sweden)

    S. K. Das

    2013-04-01

    Full Text Available Optical and physical properties of aerosols derived from multi-satellite observations (MODIS-Aqua, OMI-Aura, MISR-Terra, CALIOP-CALIPSO have been used to estimate radiative effects of the dust layer over southern India. The vertical distribution of aerosol radiative forcing and heating rates are calculated with 100 m resolution in the lower atmosphere, using temperature and relative humidity data from balloon-borne radiosonde observations. The present study investigates the optically thick dust layer of optical thickness 0.18 ± 0.06 at an altitude of 2.5 ± 0.7 km over Gadanki, transported from the Thar Desert, producing radiative forcing and heating rate of 11.5 ± 3.3 W m−2 and 0.6 ± 0.26 K day−1, respectively, with a forcing efficiency of 43 W m−2 and an effective heating rate of 4 K day−1 per unit dust optical depth. Presence of the dust layer increases radiative forcing by 60% and heating rate by 60 times at that altitude compared to non-dusty cloud-free days. Calculation shows that the radiative effects of the dust layer strongly depend on the boundary layer aerosol type and mass loading. An increase of 25% of heating by the dust layer is found over relatively cleaner regions than urban regions in southern India and further 15% of heating increases over the marine region. Such heating differences in free troposphere may have significant consequences in the atmospheric circulation and hydrological cycle over the tropical Indian region.

  7. Mechanisms of impact of greenhouse gases on the Earth's ozone layer in the Polar Regions

    Science.gov (United States)

    Zadorozhny, Alexander; Dyominov, Igor

    the expected recovery of the ozone layer here. The difference in the impact of the greenhouse gases on the ozone layer at the southern and northern polar latitudes through PCS modification is determined by the difference in temperature regimes of the Polar Regions. The mechanism of the impact of the greenhouse gases on the polar ozone by means of modification of sulphate aerosol distribution in the atmosphere has been revealed and investigated, too. Numerical experiments show that enhancement of the surface area density of sulphate aerosol in the stratosphere caused by the growth of the greenhouse gases will reduce significantly the ozone depletion during the Antarctic ozone hole.

  8. The influence of tidal winds in the formation of blanketing sporadic e-layer over equatorial Brazilian region

    Science.gov (United States)

    Resende, Laysa Cristina Araujo; Batista, Inez Staciarini; Denardini, Clezio Marcos; Batista, Paulo Prado; Carrasco, Alexander José; Andrioli, Vânia Fátima; Moro, Juliano

    2018-06-01

    This work analysis the blanketing sporadic layers (Esb) behavior over São Luís, Brazil (2° 31‧ S, 44° 16‧ W, dip: -4.80) which is classified as a transition region between equatorial and low-latitude. Hence, some peculiarities can appear as Esb occurrence instead of the common Esq, which is a non-blanketing irregularity layer. The analysis presented here was obtained using a modified version of a theoretical model for the E region (MIRE), which computes the densities of the metallic ions (Fe+ and Mg+) and the densities of the main molecular ions (NO+, O2+, N2+) by solving the continuity and momentum equations for each one of them. In that model, the Es layer physics driven by both diurnal and semidiurnal tidal winds are taken into account and it was extended in height coverage by adding a novel neutral wind model derived from the all-sky meteor radar measurements. Thus, we provide more trustworthy results related to the Es layer formation in the equatorial region. We verified the contribution of each tidal wind component to the Esb layer formation in this equatorial region. Additionally, we compared the Es layer electron density computed by MIRE with the data obtained by using the blanketing frequency parameter (fbEs) deduced from ionograms. The results show that the diurnal component of the tidal wind is more important in the Esb layer formation whereas the semidiurnal component has a little contribution in our simulations. Finally, it was verified that the modified MIRE presented here can be used to study the Esb layers occurrence over the equatorial region in the Brazilian sector.

  9. Exploring the magnetospheric boundary layer

    International Nuclear Information System (INIS)

    Hapgood, M.A.; Bryant, D.A.

    1992-01-01

    We show how, for most crossings of the boundary layer, one can construct a 'transition parameter', based on electron density and temperature, which orders independent plasma measurements into well-defined patterns which are consistent from case to case. We conclude that there is a gradual change in the balance of processes which determine the structure of the layer and suggest that there is no advantage in dividing the layer into different regions. We further conclude that the mixing processes in layer act in an organised way to give the consistent patterns revealed by the transition parameter. More active processes must sometimes take to give the extreme values (e.g. in velocity) which are seen in some crossings

  10. Application of Mastic Asphalt Waterproofing Layer in High-Speed Railway Track in Cold Regions

    Directory of Open Access Journals (Sweden)

    Song Liu

    2018-04-01

    Full Text Available Freeze-thaw damage is a typical distress incurred in road and railway engineering in cold regions. Concrete waterproofing layer is commonly used in high-speed railway tracks to prevent the penetration of surface water, however, it cracks easily under thermal stress, especially in cold regions. Recently solutions have been proposed to increase the waterproofing layer’s cracking resistance by using asphalt layers. Nonetheless, the use of emulsified asphalt as well as dense-graded asphalt mixture were not effective enough. To improve the effectiveness, in this study, mastic asphalt was designed for application as the waterproofing layer on the subgrade surface of high-speed railway tracks in cold regions. The overall performance of mastic asphalt was preliminarily evaluated by laboratory tests, then a 200-m test section was constructed for field validation in northeastern China as part of a new high-speed railway line, and water content sensors were placed inside the subgrade to monitor the performance of the mastic asphalt waterproofing layer (MAWL. The subsequent field investigation and monitoring data during the two years operation showed that MAWL dramatically outperformed the conventional concrete waterproofing layer in terms of waterproof performance. Plenty of serious cracks were found in the conventional concrete waterproofing layer, but only a limited number of local cracks were observed in MAWL. As a result, MAWL keeps the water content of subgrade at a stable level. In addition, MAWL showed relatively high stability during the two years investigation period, and no obvious deterioration was observed in the test section.

  11. Effects of a conducting E layer on classical F region cross-field plasma diffusion

    International Nuclear Information System (INIS)

    Vickrey, J.F.; Kelley, M.C.

    1982-01-01

    The rate of cross-field plasma diffusion in the F region ionosphere is significantly increased when the magnetic field lines thread a highly conducting E region below. This reduces the lifetime of small-scale F region electron density irregularities in the polar ionosphere where the presence of a highly conducting E region is comonplace. A simple mmodel is developed to describe the effects of a conducting E layer on classical F region plasma diffusion. In the absence of an E region, the difference in ion and electron diffusion rates leads to a charge separation and, hence, to an electrostatic field that retards ion diffusion. When the highly conducting magnetic field lines are tied to a conducting E region, however, electrons can flow along B to reduce the ambipolar diffusion electric field, and ions can proceed perpendicular to B at a rate approaching their own (higher) diffusion velocity. It is shown that the enhanced total diffusion rate that results depends strongly on the height of the F layer and on the ratio of the E to F region Pedersen conductivities

  12. Boundary layer polarization and voltage in the 14 MLT region

    Science.gov (United States)

    Lundin, R.; Yamauchi, M.; Woch, J.; Marklund, G.

    1995-05-01

    Viking midlatitude observations of ions and electrons in the postnoon auroral region show that field-aligned acceleration of electrons and ions with energies up to a few kiloelectron volts takes place. The characteristics of the upgoing ion beams and the local transverse electric field observed by Viking indicate that parallel ion acceleration is primarily due to a quasi-electrostatic field-aligned acceleration process below Viking altitudes, i.e., below 10,000-13,500 km. A good correlation is found between the maximum upgoing ion beam energy and the depth of the local potential well determined by the Viking electric field experiment within dayside 'ion inverted Vs.' The total transverse potential throughout the entire region near the ion inverted Vs. is generally much higher than the field-aligned potential and may reach well above 10 kV. However, the detailed mapping of the transverse potential out to the boundary layer, a fundamental issue which remains controversial, was not attempted here. An important finding in this study is the strong correlation between the maximum up going ion beam energy of dayside ion inverted Vs and the solar wind velocity. This suggests a direct coupling of the solar wind plasma dynamo/voltage generator to the region of field-aligned particle acceleration. The fact that the center of dayside ion inverted Vs coincide with convection reversals/flow stagnation and upward Birkeland currents on what appears to be closed field lines (Woch et al., 1993), suggests that field-aligned potential structures connect to the inner part of an MHD dyanmo in the low-latitude boundary layer. Thus the Viking observations substantiate the idea of a solar wind induced boundary layer polarization where negatively charged perturbations in the postnoon sector persistently develops along the magnetic field lines, establishing accelerating potential drops along the geomagnetic field lines in the 0.5-10 kV range.

  13. [Soil organic carbon mineralization of Black Locust forest in the deep soil layer of the hilly region of the Loess Plateau, China].

    Science.gov (United States)

    Ma, Xin-Xin; Xu, Ming-Xiang; Yang, Kai

    2012-11-01

    The deep soil layer (below 100 cm) stores considerable soil organic carbon (SOC). We can reveal its stability and provide the basis for certification of the deep soil carbon sinks by studying the SOC mineralization in the deep soil layer. With the shallow soil layer (0-100 cm) as control, the SOC mineralization under the condition (temperature 15 degrees C, the soil water content 8%) of Black Locust forest in the deep soil layer (100-400 cm) of the hilly region of the Loess Plateau was studied. The results showed that: (1) There was a downward trend in the total SOC mineralization with the increase of soil depth. The total SOC mineralization in the sub-deep soil (100-200 cm) and deep soil (200-400 cm) were equivalent to approximately 88.1% and 67.8% of that in the shallow layer (0-100 cm). (2) Throughout the carbon mineralization process, the same as the shallow soil, the sub-deep and deep soil can be divided into 3 stages. In the rapid decomposition phase, the ratio of the mineralization or organic carbon to the total mineralization in the sub-deep and deep layer (0-10 d) was approximately 50% of that in the shallow layer (0-17 d). In the slow decomposition phase, the ratio of organic carbon mineralization to total mineralization in the sub-deep, deep layer (11-45 d) was 150% of that in the shallow layer (18-45 d). There was no significant difference in this ratio among these three layers (46-62 d) in the relatively stable stage. (3) There was no significant difference (P > 0.05) in the mineralization rate of SOC among the shallow, sub-deep, deep layers. The stability of SOC in the deep soil layer (100-400 cm) was similar to that in the shallow soil layer and the SOC in the deep soil layer was also involved in the global carbon cycle. The change of SOC in the deep soil layer should be taken into account when estimating the effects of soil carbon sequestration in the Hilly Region of the Loess Plateau, China.

  14. Boundary-Layer Characteristics of Persistent Regional Haze Events and Heavy Haze Days in Eastern China

    Directory of Open Access Journals (Sweden)

    Peng Huaqing

    2016-01-01

    Full Text Available This paper analyzed the surface conditions and boundary-layer climate of regional haze events and heavy haze in southern Jiangsu Province in China. There are 5 types with the surface conditions which are equalized pressure (EQP, the advancing edge of a cold front (ACF, the base of high pressure (BOH, the backside of high pressure (BAH, the inverted trough of low pressure (INT, and saddle pressure (SAP with the haze days. At that time, 4 types are divided with the regional haze events and each of which has a different boundary-layer structure. During heavy haze, the surface mainly experiences EQP, ACF, BOH, BAH, and INT which also have different boundary-layer structures.

  15. Numerical investigation of a spatially developing turbulent natural convection boundary layer along a vertical heated plate

    International Nuclear Information System (INIS)

    Nakao, Keisuke; Hattori, Yasuo; Suto, Hitoshi

    2017-01-01

    Highlights: • A large-eddy simulation of a spatially developing natural convection boundary layer is conducted. • First- and second-order moments of the heat and momentum showed a reasonable agreement with past experiments. • Coherent structure of turbulent vortex inherent in this boundary layer is discussed. - Abstract: Large-eddy simulation (LES) on a spatially developing natural convection boundary layer along a vertical heated plate was conducted. The heat transfer rate, friction velocity, mean velocity and temperature, and second-order turbulent properties both in the wall-normal and the stream-wise direction showed reasonable agreement with the findings of past experiments. The spectrum of velocity and temperature fluctuation showed a -2/3-power decay slope and -2-power decay slope respectively. Quadrant analysis revealed the inclination on Q1 and Q3 in the Reynolds stress and turbulent heat flux, changing their contribution along the distance from the plate surface. Following the convention, we defined the threshold region where the stream-wise mean velocity takes local maximum, the inner layer which is closer to the plate than the threshold region, the outer layer which is farther to the plate than the threshold region. The space correlation of stream-wise velocity tilted the head toward the wall in the propagating direction in the outer layer; on the other hand, the correlated motion had little inclination in the threshold region. The time history of the second invariant of gradient tensor Q revealed that the vortex strength oscillates both in the inner and the outer layers in between the laminar and the transition region. In the turbulent region, the vortex was often dominant in the outer layer. Instantaneous three-dimensional visualization of Q revealed the existence of high-speed fluid parcels associated with arch-shape vortices. These results were considered as an intrinsic structure in the outer layer, which is symmetrical to the structure of

  16. EPA Region 1 - Map Layers for Valley ID Tool (Hosted Feature Service)

    Science.gov (United States)

    The Valley Service Feature Layer hosts spatial data for EPA Region 1's Valley Identification Tool. These layers contain attribute information added by EPA R1 GIS Center to help identify populated valleys:- Fac_2011NEI: Pollution sources selected from the National Emissions Inventory (EPA, 2011).- NE_Towns_PopValleys: New England Town polygons (courtesy USGS), with Population in Valleys and Population Density in Valleys calculated by EPA R1 GIS, from 2010 US Census blocks. - VT_E911: Vermont residences (courtesy VT Center for Geographic Information E-911).

  17. In situ atomic layer nitridation on the top and down regions of the amorphous and crystalline high-K gate dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Meng-Chen [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Lee, Min-Hung [Institute of Electro-Optical Science and Technology, National Taiwan Normal University, Taipei 11677, Taiwan (China); Kuo, Chin-Lung; Lin, Hsin-Chih [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Chen, Miin-Jang, E-mail: mjchen@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

    2016-11-30

    Highlights: • The structural and electrical characteristics of the ZrO{sub 2} high-K dielectrics, treated with the in situ atomic layer doping of nitrogen into the top and down regions (top and down nitridation, TN and DN, respectively), were investigated. • The amorphous DN sample has a lower leakage current density (J{sub g}) than the amorphous TN sample, attributed to the formation of SiO{sub x}N{sub y} in the interfacial layer (IL). • The crystalline TN sample exhibited a lower CET and a similar J{sub g} as compared with the crystalline DN sample, which can be ascribed to the suppression of IL regrowth. • The crystalline ZrO{sub 2} with in situ atomic layer doping of nitrogen into the top region exhibited superior scaling limit, electrical characteristics, and reliability. - Abstract: Amorphous and crystalline ZrO{sub 2} gate dielectrics treated with in situ atomic layer nitridation on the top and down regions (top and down nitridation, abbreviated as TN and DN) were investigated. In a comparison between the as-deposited amorphous DN and TN samples, the DN sample has a lower leakage current density (J{sub g}) of ∼7 × 10{sup −4} A/cm{sup 2} with a similar capacitance equivalent thickness (CET) of ∼1.53 nm, attributed to the formation of SiO{sub x}N{sub y} in the interfacial layer (IL). The post-metallization annealing (PMA) leads to the transformation of ZrO{sub 2} from the amorphous to the crystalline tetragonal/cubic phase, resulting in an increment of the dielectric constant. The PMA-treated TN sample exhibits a lower CET of 1.22 nm along with a similar J{sub g} of ∼1.4 × 10{sup −5} A/cm{sup 2} as compared with the PMA-treated DN sample, which can be ascribed to the suppression of IL regrowth. The result reveals that the nitrogen engineering in the top and down regions has a significant impact on the electrical characteristics of amorphous and crystalline ZrO{sub 2} gate dielectrics, and the nitrogen incorporation at the top of crystalline

  18. Polycyclic aromatic hydrocarbons (PAHs) associated with PM2.5 within boundary layer: Cloud/fog and regional transport.

    Science.gov (United States)

    Yang, Minmin; Wang, Yan; Li, Hongli; Li, Tao; Nie, Xiaoling; Cao, Fangfang; Yang, Fengchun; Wang, Zhe; Wang, Tao; Qie, Guanghao; Jin, Tong; Du, Lili; Wang, Wenxing

    2018-06-15

    A study of PM 2.5 -associated PAHs analysis at Mount Lushan (1165m) was conducted to investigate the distributions of PAHs in PM 2.5 and influences of cloud/fog. The main purpose was to quantify the main emission sources of PAHs and estimate regional transport effects within the boundary layer. Mount Lushan is located between the boundary layer and troposphere, which is an ideal site for atmosphere transport investigation. The concentrations of PAHs in PM 2.5 were analyzed with GC-MS. The results showed that the volume concentration was 6.98ng/m 3 with a range from 1.47 to 25.17ng/m 3 and PAHs mass were 160.24μg/g (from 63.86 to 427.97μg/g) during the sampling time at Mount Lushan. The dominant compounds are BbF, Pyr and BP. In terms of aromatic-ring PAHs distributions, 4-6-ring PAHs are predominant, indicating that the high-ring PAHs tend to contribute more than low-ring PAHs in particulates. Due to frequent cloud/fog days at Mount Lushan, PAHs concentrations in the PM 2.5 were determined before and after cloud/fog weather. The results demonstrated that the cloud/fog and rain conditions cause lower PAHs levels. Regression analysis was used for studying the relationship of PAHs distributions with meteorological conditions like temperature, humidity and wind. The results showed that the temperature and wind speed were inversely related with PAHs concentration but humidity had no significant relationship. Furthermore, backward trajectories and PCA combined with DR (diagnostic ratio analysis) were employed to identify the influences of regional transport and main emission sources. The results revealed that PAHs in PM 2.5 were mainly affected by regional transport with the main emissions by mobile vehicle and steel industry, which contributed about 56.0% to the total PAHs in the area of Mount Lushan. In addition, backward trajectories revealed that the dominant air masses were from the northwest accounting for about one third of total PAHs. Copyright © 2018

  19. 'Blueberry' Layers Indicate Watery Origins

    Science.gov (United States)

    2004-01-01

    This microscopic image, taken at the outcrop region dubbed 'El Capitan' near the Mars Exploration Rover Opportunity's landing site, reveals millimeter-scale (.04 inch-scale) layers in the lower portion. This same layering is hinted at by the fine notches that run horizontally across the sphere-like grain or 'blueberry' in the center left. The thin layers do not appear to deform around the blueberry, indicating that these geologic features are concretions and not impact spherules or ejected volcanic material called lapilli. Concretions are balls of minerals that form in pre-existing wet sediments. This image was taken by the rover's microscopic imager on the 29th martian day, or sol, of its mission. The observed area is about 3 centimeters (1.2 inches) across.

  20. Redeployment of germ layers related TFs shows regionalized expression during two non-embryonic developments.

    Science.gov (United States)

    Ricci, Lorenzo; Cabrera, Fabien; Lotito, Sonia; Tiozzo, Stefano

    2016-08-01

    In all non-vertebrate metazoan phyla, species that evolved non-embryonic developmental pathways as means of propagation or regeneration can be found. In this context, new bodies arise through asexual reproduction processes (such as budding) or whole body regeneration, that lack the familiar temporal and spatial cues classically associated with embryogenesis, like maternal determinants, or gastrulation. The molecular mechanisms underlying those non-embryonic developments (i.e., regeneration and asexual reproduction), and their relationship to those deployed during embryogenesis are poorly understood. We have addressed this question in the colonial ascidian Botryllus schlosseri, which undergoes an asexual reproductive process via palleal budding (PB), as well as a whole body regeneration by vascular budding (VB). We identified early regenerative structures during VB and then followed the fate of differentiating tissues during both non-embryonic developments (PB and VB) by monitoring the expression of genes known to play key functions in germ layer specification with well conserved expression patterns in solitary ascidian embryogenesis. The expression patterns of FoxA1, GATAa, GATAb, Otx, Bra, Gsc and Tbx2/3 were analysed during both PB and VB. We found that the majority of these transcription factors were expressed during both non-embryonic developmental processes, revealing a regionalization of the palleal and vascular buds. Knockdown of GATAa by siRNA in palleal buds confirmed that preventing the correct development of one of these regions blocks further tissue specification. Our results indicate that during both normal and injury-induced budding, a similar alternative developmental program operates via early commitment of epithelial regions. Copyright © 2016. Published by Elsevier Inc.

  1. Self-consistent electrostatic simulations of reforming double layers in the downward current region of the aurora

    Directory of Open Access Journals (Sweden)

    H. Gunell

    2015-10-01

    Full Text Available The plasma on a magnetic field line in the downward current region of the aurora is simulated using a Vlasov model. It is found that an electric field parallel to the magnetic fields is supported by a double layer moving toward higher altitude. The double layer accelerates electrons upward, and these electrons give rise to plasma waves and electron phase-space holes through beam–plasma interaction. The double layer is disrupted when reaching altitudes of 1–2 Earth radii where the Langmuir condition no longer can be satisfied due to the diminishing density of electrons coming up from the ionosphere. During the disruption the potential drop is in part carried by the electron holes. The disruption creates favourable conditions for double layer formation near the ionosphere and double layers form anew in that region. The process repeats itself with a period of approximately 1 min. This period is determined by how far the double layer can reach before being disrupted: a higher disruption altitude corresponds to a longer repetition period. The disruption altitude is, in turn, found to increase with ionospheric density and to decrease with total voltage. The current displays oscillations around a mean value. The period of the oscillations is the same as the recurrence period of the double layer formations. The oscillation amplitude increases with increasing voltage, whereas the mean value of the current is independent of voltage in the 100 to 800 V range covered by our simulations. Instead, the mean value of the current is determined by the electron density at the ionospheric boundary.

  2. Nucleation and Early Stages of Layer-by-Layer Growth of Metal Organic Frameworks on Surfaces

    Science.gov (United States)

    2015-01-01

    High resolution atomic force microscopy (AFM) is used to resolve the evolution of crystallites of a metal organic framework (HKUST-1) grown on Au(111) using a liquid-phase layer-by-layer methodology. The nucleation and faceting of individual crystallites is followed by repeatedly imaging the same submicron region after each cycle of growth and we find that the growing surface is terminated by {111} facets leading to the formation of pyramidal nanostructures for [100] oriented crystallites, and triangular [111] islands with typical lateral dimensions of tens of nanometres. AFM images reveal that crystallites can grow by 5–10 layers in each cycle. The growth rate depends on crystallographic orientation and the morphology of the gold substrate, and we demonstrate that under these conditions the growth is nanocrystalline with a morphology determined by the minimum energy surface. PMID:26709359

  3. High-latitude Pc 1 bursts arising in the dayside boundary layer region

    International Nuclear Information System (INIS)

    Hansen, H.J.; Fraser, B.J.; Menk, F.W.; Hu, Y.D.; Newell, P.T.; Meng, C.I.; Morris, R.J.

    1992-01-01

    Dayside Pc 1 geomagnetic pulsation bursts have been studied using a three-station array of induction magnetometers located at high latitudes. Associated magnetic variations in the form of solitary pulses often lead the Pc 1 bursts by 1 to 2 min. These pulses are typically associated with riometer absorption events and consequently the precipitation of fluxes of keV electrons. The Pc 1 bursts are interpreted as resulting from ion cyclotron waves which have propagated to the ionosphere from the equatorial boundary layer region. The associated boundary layer ions, identified by the low-altitude DMSP F7 satellite, range between 1 and 5 keV in energy. These particles are considered to be the most likely free energy source for the ion cyclotron waves. It is considered that such resonant ions enter the magnetosphere via the cleft and cusp because this enables a prenoon time of occurrence of most of the observations to be explained. Measured time delays of 40 to 120 s between the associated riometer absorption and Pc 2 bursts are consistent with an ion cyclotron wave generations region located in the equatorial magnetosphere

  4. Observation of electron biteout regions below sporadic E layers at polar latitudes

    Directory of Open Access Journals (Sweden)

    G. A. Lehmacher

    2015-03-01

    Full Text Available The descent of a narrow sporadic E layer near 95 km altitude over Poker Flat Research Range in Alaska was observed with electron probes on two consecutive sounding rockets and with incoherent scatter radar during a 2 h period near magnetic midnight. A series of four trimethyl aluminum chemical releases demonstrated that the Es layer remained just slightly above the zonal wind node, which was slowly descending due to propagating long-period gravity waves. The location of the layer is consistent with the equilibrium position due to combined action of the wind shear and electric fields. Although the horizontal electric field could not be measured directly, we estimate that it was ~ 2 mV m−1 southward, consistent with modeling the vertical ion drift, and compatible with extremely quiet conditions. Both electron probes observed deep biteout regions just below the Es enhancements, which also descended with the sporadic layers. We discuss several possibilities for the cause of these depletions; one possibility is the presence of negatively charged, nanometer-sized mesospheric smoke particles. Such particles have recently been detected in the upper mesosphere, but not yet in immediate connection with sporadic E. Our observations of electron depletions suggest a new process associated with sporadic E.

  5. Mechanisms of Mixed-Layer Salinity Seasonal Variability in the Indian Ocean

    Science.gov (United States)

    Köhler, Julia; Serra, Nuno; Bryan, Frank O.; Johnson, Benjamin K.; Stammer, Detlef

    2018-01-01

    Based on a joint analysis of an ensemble mean of satellite sea surface salinity retrievals and the output of a high-resolution numerical ocean circulation simulation, physical processes are identified that control seasonal variations of mixed-layer salinity (MLS) in the Indian Ocean, a basin where salinity changes dominate changes in density. In the northern and near-equatorial Indian Ocean, annual salinity changes are mainly driven by respective changes of the horizontal advection. South of the equatorial region, between 45°E and 90°E, where evaporation minus precipitation has a strong seasonal cycle, surface freshwater fluxes control the seasonal MLS changes. The influence of entrainment on the salinity variance is enhanced in mid-ocean upwelling regions but remains small. The model and observational results reveal that vertical diffusion plays a major role in precipitation and river runoff dominated regions balancing the surface freshwater flux. Vertical diffusion is important as well in regions where the advection of low salinity leads to strong gradients across the mixed-layer base. There, vertical diffusion explains a large percentage of annual MLS variance. The simulation further reveals that (1) high-frequency small-scale eddy processes primarily determine the salinity tendency in coastal regions (in particular in the Bay of Bengal) and (2) shear horizontal advection, brought about by changes in the vertical structure of the mixed layer, acts against mean horizontal advection in the equatorial salinity frontal regions. Observing those latter features with the existing observational components remains a future challenge.

  6. Measuring the Impact of Wildfire on Active Layer Thickness in a Discontinuous Permafrost region using Interferometric Synthetic Aperture Radar (InSAR)

    Science.gov (United States)

    Michaelides, R. J.; Schaefer, K. M.; Zebker, H. A.; Liu, L.; Chen, J.; Parsekian, A.

    2017-12-01

    In permafrost regions, the active layer is defined as the uppermost portion of the permafrost table that is subject to annual freeze/thaw cycles. The active layer plays a crucial role in surface processes, surface hydrology, and vegetation succession; furthermore, trapped methane, carbon dioxide, and other greenhouse gases in permafrost are released into the atmosphere as permafrost thaws. A detailed understanding of active layer dynamics is therefore critical towards understanding the interactions between permafrost surface processes, freeze/thaw cycles, and climate-especially in regions across the Arctic subject to long-term permafrost degradation. The Yukon-Kuskokwim (YK) delta in southwestern Alaska is a region of discontinuous permafrost characterized by surface lakes, wetlands, and thermokarst depressions. Furthermore, extensive wildfires have burned across the YK delta in 2006, 2007, and 2015, impacting vegetation cover, surface soil moisture, and the active layer. Using data from the ALOS PALSAR, ALOS-2 PALSAR-2, and Sentinel-1A/B space borne synthetic aperture radar (SAR) systems, we generate a series of interferograms over a study site in the YK delta spanning 2007-2011, and 2014-present. Using the ReSALT (Remotely-Sensed Active Layer Thickness) technique, we demonstrate that active layer can be characterized over most of the site from the relative interferometric phase difference due to ground subsidence and rebound associated with the seasonal active layer freeze/thaw cycle. Additionally, we show that this technique successfully discriminates between burned and unburned regions, and can resolve increases in active layer thickness in burned regions on the order of 10's of cms. We use the time series of interferograms to discuss permafrost recovery following wildfire burn, and compare our InSAR observations with GPR and active layer probing data from a 2016 summer field campaign to the study site. Finally, we compare the advantages and disadvantages of

  7. [Effects of Acupuncture Stimulation of Different Layers of "Tianshu" (ST 25) Region on Changes of Intra-colonic Pressure in Normal Rats].

    Science.gov (United States)

    Sun, Xue-Yi; Yu, Zhi; Chen, Zhi-Yu; Xu, Bin

    2018-02-25

    To observe the effect of manual acupuncture stimulation of different layers (skin, muscle, peritoneum, sub-peritoneum) of "Tianshu" (ST 25) region on proximal colonic pressure in normal rats. Forty-eight male SD rats were divided into 6 groups: all layer-needling, brushing, cutaneous needling, muscular needling, peritoneum-needling and sub-peritoneum-needling groups ( n =8 in each group). Manual needling or brushing was applied to "Tianshu" (ST 25) region. The colonic internal pressure was measured by using an amplifier and a pressure transducer-connected balloon which was implanted into the colonic cavity about 6 cm from the ileocecal valve. For rats of the all-layer needling group, an acupuncture needle was inserted into ST 25 about 1 cm deep and rotated for a while, for rats of the brushing group, a Chinese calligraphy brush pen was used to brush the skin hair for 1 min. For rats of the rest 4 groups, an acupuncture needle was inserted into the skin, muscle layer after cutting open the skin (about 0.1 cm), the peritoneum layer after cutting open the skin and muscle layers, and the sub-peritoneum layer after cutting open the skin, muscle and peritoneum layers, respectively, and rotated using the uniform reinforcing-reducing technique for about 1 min at a frequency of 120 twirlings per minute every time. During manual needling stimulation of the full layers, cutaneous layer, muscle layer, peritoneum layer and the sub-peritoneum layer of bilateral "Tianshu" (ST 25), the internal pressure of proximal colon was significantly decreased relevant to pre-stimulation in each group ( P 0.05). During hair brushing of ST 25 region, the colonic pressure was observably increased relevant to pre-needling stimulation ( P ST 25 on both sides may lower internal pressure of proximal colon in normal rats, suggesting their involvement of acupuncture effect in relaxing proximal colonic contraction.

  8. The Implement of a Multi-layer Frozen Soil Scheme into SSiB3 and its Evaluation over Cold Regions

    Science.gov (United States)

    Li, Q.

    2016-12-01

    The SSiB3 is a biophysics-based model of land-atmosphere interactions and is designed for global and regional studies. It has three soil layers, three snow layers, as well as one vegetation layer. Soil moisture of the three soil layers, interception water store for the canopy, subsurface soil temperature, ground temperature, canopy temperature and snow water equivalent are all predicted based on the water and energy balance at canopy, soil and snow. SSiB3 substantially enhances the model's capability for cold season studies and produces reasonable results compared with observations. However, frozen soil processes are ignored in the SSiB3 and may have effects on the interannual variability of soil temperature and deep soil memory. A multi-layer comprehensive frozen soil scheme (FSM), which is developed for climate study has been implemented into the SSiB3 to describe soil heat transfer and water flow affected by frozen processed in soil. In the coupled SSiB3-FSM, both liquid water and ice content have been taken into account in the frozen soil hydrologic and thermal property parameterization. The maximum soil layer depth could reach 10 meters thick depending on land conditions. To better evaluate the models' performance, the coupled offline SSiB3-FSM and SSiB3 have been driven from 1948 to 1958 by the Princeton global meteorological data set, respectively. For the 10yrs run, the coupled SSiB3-FSM almost captures the features over different regions, especially cold regions. In order to analysis and compare the differences of SSIB3-FSM and SSIB3 in detail, monthly mean surface temperature for different regions are compared with CAMS data. The statistical results of surface skin temperature show that high latitude regions, Africa, Eastern Australia, and North American monsoon regions have been greatly improved in SSIB3-FSM. For the global statistics, the RMSE of the surface temperature simulated by SSiB3-FSM can be improved about 0.6K compared to SSiB3. In this study

  9. [Characteristics of Winter Atmospheric Mixing Layer Height in Beijing-Tianjin-Hebei Region and Their Relationship with the Atmospheric Pollution].

    Science.gov (United States)

    Li, Meng; Tang, Gui-qian; Huang, Jun; Liu, Zi-rui; An, Jun-lin; Wang, Yue-si

    2015-06-01

    Atmospheric mixing layer height (MLH) is one of the main factors affecting the atmospheric diffusion and plays an important role in air quality assessment and distribution of the pollutants. Based on the ceilometers data, this paper has made synchronous observation on MLH in Beijing-Tianjin-Hebei region (Beijing, Tianjin, Shijiazhuang and Qinhuangdao) in heavy polluted February 2014 and analyzed the respective overall change and its regional features. Results show that in February 2014,the average of mixing layer height in Qinhuangdao is the highest, up to 865 +/- 268 m, and in Shijiazhuang is the lowest (568 +/- 207 m), Beijing's and Tianjin's are in between, 818 +/- 319 m and 834 +/- 334 m respectively; Combined with the meteorological data, we find that radiation and wind speed are main factors of the mixing layer height; The relationship between the particle concentration and mixing layer height in four sites suggests that mixing layer is less than 800 m, concentration of fine particulate matter in four sites will exceed the national standard (GB 3095-2012, 75 microg x m(-3)). During the period of observation, the proportion of days that mixing layer is less than 800 m in Beijing, Tianjin, Shijiazhuang and Qinhuangdao are 50%, 43%, 80% and 50% respectively. Shijiazhuang though nearly formation contaminant concentration is high, within the atmospheric mixed layer pollutant load is not high. Unfavorable atmospheric diffusion conditions are the main causes of heavy pollution in Shijiazhuang for a long time. The results of the study are of great significance for cognitive Beijing-Tianjin-Hebei area pollution distribution, and can provide a scientific reference for reasonable distribution of regional pollution sources.

  10. Planetary and tidal wave-type oscillations in the ionospheric sporadic E layers over Tehran region

    Science.gov (United States)

    Karami, K.; Ghader, S.; Bidokhti, A. A.; Joghataei, M.; Neyestani, A.; Mohammadabadi, A.

    2012-04-01

    It is believed that in the lower ionosphere, particularly in the ionospheric sporadic E (Es) layers (90-130 km), the planetary and tidal wave-type oscillations in the ionized component indicate the planetary and tidal waves in the neutral atmosphere. In the present work, the presence of wave-type oscillations, including planetary and tidal waves in the ionospheric sporadic E layers over Tehran region is examined. Data measured by a digital ionosonde at the ionospheric station of the Institute of Geophysics, University of Tehran, from July 2006 to June 2007 are used to investigate seasonal variations of planetary and tidal waves activities. For the purpose of accurate comparison between different seasons, wavelet transform is applied to time series of foEs and h‧Es, namely, the critical frequency and virtual height of Es layers, respectively. The results show that the sporadic E layers over Tehran region are strongly under the influence of upward propagation of waves from below. More specifically, among diverse range of periodicities in the sporadic E layers, we found that diurnal (24 hours) and semidiurnal (12 hours) oscillations in all seasons for both parameters. Moreover, terdiurnal (8 hours) tide-like variation is observed during spring and summer for foEs parameter and summer and winter for h‧Es. Furthermore, the results show that diurnal tidal waves obtain their maximum activities during autumn and winter seasons, and their activities decrease during the late spring and summer. In addition, periods of about 2, 4, 6, 10, 14, and 16 days in our observation verifies the hypothesis of upward propagation of planetary waves from lower atmosphere to the ionosphere. Moreover, planetary waves have their maximum activities during equinox.

  11. About the nature of regional thermal anomaly in the Semipalatinsk Test Site region revealed basing on remote space sensing data

    International Nuclear Information System (INIS)

    Melent'ev, M.I.; Velikanov, A.E.

    2003-01-01

    A thermal anomaly, (more than 20,000 sq. km) discovered in the Semipalatinsk Test Site region in the pictures from space, is observed every year on certain days mainly in winter-spring season. Appearance of the thermal anomaly often coincides with days of intensive fall of atmospheric precipitation and possible thawing of snow cover together with decreasing of ozone concentration in atmosphere. The explanation of thermal anomaly in the Semipalatinsk Test Site region due to nuclear reaction caused by the energy of radionuclide radioactive decay deposited in a soil layer after ground and air nuclear explosions and radiolysis processes in soil solutions is given in this article. (author)

  12. Master stability functions reveal diffusion-driven pattern formation in networks

    Science.gov (United States)

    Brechtel, Andreas; Gramlich, Philipp; Ritterskamp, Daniel; Drossel, Barbara; Gross, Thilo

    2018-03-01

    We study diffusion-driven pattern formation in networks of networks, a class of multilayer systems, where different layers have the same topology, but different internal dynamics. Agents are assumed to disperse within a layer by undergoing random walks, while they can be created or destroyed by reactions between or within a layer. We show that the stability of homogeneous steady states can be analyzed with a master stability function approach that reveals a deep analogy between pattern formation in networks and pattern formation in continuous space. For illustration, we consider a generalized model of ecological meta-food webs. This fairly complex model describes the dispersal of many different species across a region consisting of a network of individual habitats while subject to realistic, nonlinear predator-prey interactions. In this example, the method reveals the intricate dependence of the dynamics on the spatial structure. The ability of the proposed approach to deal with this fairly complex system highlights it as a promising tool for ecology and other applications.

  13. On the nature of the plasma sheet boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Hones, E.W. Jr. (Mission Research Corp., Los Alamos, NM (USA) Los Alamos National Lab., NM (USA))

    1990-01-01

    The regions of the plasma sheet adjacent to the north and south lobes of the magnetotail have been described by many experimenters as locations of beams of energetic ions and fast-moving plasma directed primarily earthward and tailward along magnetic field lines. Measurements taken as satellites passed through one or the other of these boundary layers have frequently revealed near-earth mirroring of ions and a vertical segregation of velocities of both earthward-moving and mirroring ions with the fastest ions being found nearest the lobe-plasma sheet interface. These are features expected for particles from a distant tail source {bar E} {times} {bar B} drifting in a dawn-to-dusk electric field and are consistent with the source being a magnetic reconnection region. The plasma sheet boundary layers are thus understood as separatrix layers, bounded at their lobeward surfaces by the separatrices from the distant neutral line. This paper will review the observations that support this interpretation. 10 refs., 7 figs.

  14. Modeling of the heat transfer in bypass transitional boundary-layer flows

    Science.gov (United States)

    Simon, Frederick F.; Stephens, Craig A.

    1991-01-01

    A low Reynolds number k-epsilon turbulence model and conditioned momentum, energy and turbulence equations were used to predict bypass transition heat transfer on a flat plate in a high-disturbance environment with zero pressure gradient. The use of conditioned equations was demonstrated to be an improvement over the use of the global-time-averaged equations for the calculation of velocity profiles and turbulence intensity profiles in the transition region of a boundary layer. The approach of conditioned equations is extended to include heat transfer and a modeling of transition events is used to predict transition onset and the extent of transition on a flat plate. The events, which describe the boundary layer at the leading edge, result in boundary-layer regions consisting of: (1) the laminar, (2) pseudolaminar, (3) transitional, and (4) turbulent boundary layers. The modeled transition events were incorporated into the TEXSTAN 2-D boundary-layer code which is used to numerically predict the heat transfer. The numerical predictions in general compared well with the experimental data and revealed areas where additional experimental information is needed.

  15. Fabrication and characterization of ultrathin dextran layers: Time dependent nanostructure in aqueous environments revealed by OWLS.

    Science.gov (United States)

    Saftics, Andras; Kurunczi, Sándor; Szekrényes, Zsolt; Kamarás, Katalin; Khánh, Nguyen Quoc; Sulyok, Attila; Bősze, Szilvia; Horvath, Robert

    2016-10-01

    Surface coatings of the polysaccharide dextran and its derivatives are key ingredients especially in label-free biosensors for the suppression of non-specific binding and for receptor immobilization. Nevertheless, the nanostructure of these ultrathin coatings and its tailoring by the variation of the preparation conditions have not been profoundly characterized and understood. In this work carboxymethylated dextran (CMD) was prepared and used for fabricating ultrathin surface coatings. A grafting method based on covalent coupling to aminosilane- and epoxysilane-functionalized surfaces was applied to obtain thin CMD layers. The carboxyl moiety of the CMD was coupled to the aminated surface by EDC-NHS reagents, while CMD coupling through epoxysilane molecules was performed without any additional reagents. The surface analysis following the grafting procedures consisted of X-ray photoelectron spectroscopy (XPS), attenuated total reflection infrared spectroscopy (ATR-IR), spectroscopic ellipsometry, atomic force microscopy (AFM) and optical waveguide lightmode spectroscopy (OWLS). The XPS and AFM measurements showed that the grafting resulted in a very thin dextran layer of a few nanometers. The OWLS method allowed devising the structure of the interfacial dextran layers by the evaluation of the optogeometrical parameters. The alteration in the nanostructure of the CMD layer with the chemical composition of the silane coverage and the pH of the grafting solution was revealed by in situ OWLS, specifically, lain down chains were found to be prevalent on the surface under neutral and basic conditions on epoxysilylated surfaces. The developed methodologies allowed to design and fabricate nanometer scale CMD layers with well-controlled surface structure, which are very difficult to characterize in aqueous environments using present instrumentations and highly hydrated surface layers. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Initial investigations of microscale cellular convection in an equatorial marine atmospheric boundary layer revealed by lidar

    Science.gov (United States)

    Cooper, D. I.; Eichinger, W. E.; Ecke, R. E.; Kao, J. C. Y.; Reisner, J. M.; Tellier, L. L.

    During the Combined Sensor Program (CSP) in March of 1996, the Los Alamos National Laboratory (LANL) fielded an advanced scanning Raman lidar. The lidar was part of a larger suite of micrometeorological sensors to quantify processes associated with the ocean-atmosphere interface, including intermittency and coherent atmospheric features in the “warm pool” of the Tropical Western Pacific (TWP) near Manus Island (2° S. lat, 147° E. long). Initial inspection of the data has revealed excellent information on the microscale vertical and horizontal spatial and temporal structure of the equatorial Marine Atmospheric Boundary Layer (MABL). The data from this experiment have added to the increasing body of measurements on surface layer convection and intermittency including, for the first time, the observation of microscale cellular convective structures such as hexagonal patterns associated with Rayleigh-Bénard cells.

  17. Derivation of Zagarola-Smits scaling in zero-pressure-gradient turbulent boundary layers

    Science.gov (United States)

    Wei, Tie; Maciel, Yvan

    2018-01-01

    This Rapid Communication derives the Zagarola-Smits scaling directly from the governing equations for zero-pressure-gradient turbulent boundary layers (ZPG TBLs). It has long been observed that the scaling of the mean streamwise velocity in turbulent boundary layer flows differs in the near surface region and in the outer layer. In the inner region of small-velocity-defect boundary layers, it is generally accepted that the proper velocity scale is the friction velocity, uτ, and the proper length scale is the viscous length scale, ν /uτ . In the outer region, the most generally used length scale is the boundary layer thickness, δ . However, there is no consensus on velocity scales in the outer layer. Zagarola and Smits [ASME Paper No. FEDSM98-4950 (1998)] proposed a velocity scale, U ZS=(δ1/δ ) U∞ , where δ1 is the displacement thickness and U∞ is the freestream velocity. However, there are some concerns about Zagarola-Smits scaling due to the lack of a theoretical base. In this paper, the Zagarola-Smits scaling is derived directly from a combination of integral, similarity, and order-of-magnitude analysis of the mean continuity equation. The analysis also reveals that V∞, the mean wall-normal velocity at the edge of the boundary layer, is a proper scale for the mean wall-normal velocity V . Extending the analysis to the streamwise mean momentum equation, we find that the Reynolds shear stress in ZPG TBLs scales as U∞V∞ in the outer region. This paper also provides a detailed analysis of the mass and mean momentum balance in the outer region of ZPG TBLs.

  18. Sparse genetic tracing reveals regionally specific functional organization of mammalian nociceptors.

    Science.gov (United States)

    Olson, William; Abdus-Saboor, Ishmail; Cui, Lian; Burdge, Justin; Raabe, Tobias; Ma, Minghong; Luo, Wenqin

    2017-10-12

    The human distal limbs have a high spatial acuity for noxious stimuli but a low density of pain-sensing neurites. To elucidate mechanisms underlying regional differences in processing nociception, we sparsely traced non-peptidergic nociceptors across the body using a newly generated Mrgprd CreERT2 mouse line. We found that mouse plantar paw skin is also innervated by a low density of Mrgprd + nociceptors, while individual arbors in different locations are comparable in size. Surprisingly, the central arbors of plantar paw and trunk innervating nociceptors have distinct morphologies in the spinal cord. This regional difference is well correlated with a heightened signal transmission for plantar paw circuits, as revealed by both spinal cord slice recordings and behavior assays. Taken together, our results elucidate a novel somatotopic functional organization of the mammalian pain system and suggest that regional central arbor structure could facilitate the "enlarged representation" of plantar paw regions in the CNS.

  19. Direct measurements of wall shear stress by buried wire gages in a shock-wave boundary-layer interaction region

    Science.gov (United States)

    Murthy, V. S.; Rose, W. C.

    1977-01-01

    Detailed measurements of wall shear stress (skin friction) were made with specially developed buried wire gages in the interaction regions of a Mach 2.9 turbulent boundary layer with externally generated shocks. Separation and reattachment points inferred by these measurements support the findings of earlier experiments which used a surface oil flow technique and pitot profile measurements. The measurements further indicate that the boundary layer tends to attain significantly higher skin-friction values downstream of the interaction region as compared to upstream. Comparisons between measured wall shear stress and published results of some theoretical calculation schemes show that the general, but not detailed, behavior is predicted well by such schemes.

  20. Electromagnetic Pulse of a Vertical Electric Dipole in the Presence of Three-Layered Region

    Directory of Open Access Journals (Sweden)

    D. Cheng

    2015-01-01

    Full Text Available Approximate formulas are obtained for the electromagnetic pulses due to a delta-function current in a vertical electric dipole on the planar surface of a perfect conductor coated by a dielectric layer. The new approximated formulas for the electromagnetic field in time domain are retreated analytically and some new results are obtained. Computations and discussions are carried out for the time-domain field components radiated by a vertical electric dipole in the presence of three-layered region. It is shown that the trapped-surface-wave terms should be included in the total transient field when both the vertical electric dipole and the observation point are on or near the planar surface of the dielectric-coated earth.

  1. Seasonal variability in virtual height of ionospheric f/sub 2/ layer at the pakistan atmospheric region

    International Nuclear Information System (INIS)

    Jilani, A.A.; Afridi, F.A.K.; Mian, K.; Zai, M.A.K.Y.

    2013-01-01

    The aim of this study was to assess the seasonal variability in virtual height of ionospheric F/sub 2/ layer for Pakistan's atmospheric region (PAR). In this communication virtual height variations have been analyzed by the descriptive statistical techniques. These methodologies comprise an autoregressive strategy, linear regression and polynomial regression. The relevance of these models has been illuminated using predicted values of different parameters under the seasonal variation of ionospheric F/sub 2/ layer in virtual height that affect the radio wave propagation through the ionosphere. These techniques are implemented to theorize the physical process of varying the virtual heights that leads this study towards formulating the variations due to interaction of radio wave propagation with this ionospheric layer. (author)

  2. Study of sporadic E layers based on GPS radio occultation measurements and digisonde data over the Brazilian region

    Science.gov (United States)

    Resende, Laysa C. A.; Arras, Christina; Batista, Inez S.; Denardini, Clezio M.; Bertollotto, Thainá O.; Moro, Juliano

    2018-04-01

    This work presents new results about sporadic E-layers (Es layers) using GPS (global positioning system) radio occultation (RO) measurements obtained from the FORMOSAT-3/COSMIC satellites and digisonde data. The RO profiles are used to study the Es layer occurrence as well as its intensity of the signal-to-noise ratio (SNR) of the 50 Hz GPS L1 signal. The methodology was applied to identify the Es layer on RO measurements over Cachoeira Paulista, a low-latitude station in the Brazilian region, in which the Es layer development is not driven tidal winds only as it is at middle latitudes. The coincident events were analyzed using the RO technique and ionosonde observations during the year 2014 to 2016. We used the electron density obtained using the blanketing frequency parameter (fbEs) and the Es layer height (h'Es) acquired from the ionograms to validate the satellite measurements. The comparative results show that the Es layer characteristics extracted from the RO measurements are in good agreement with the Es layer parameters from the digisonde.

  3. Morphology, chemical composition , and electrochemical characteristics of colored titanium passive layers

    International Nuclear Information System (INIS)

    Jerkiewicz, G.; Hrapovic, S.; Vatankhah, G.; Luan, B.L.

    1999-01-01

    Brightly and uniformly colored passive layers on Ti are formed by application of AC polarization in aqueous NH 4 BF 4 . A wide spectrum of well-defined colors is accomplished by varying the AC voltage. The passive films are stable in the ambient and in aqueous chloride, perchlorate, sulfate solutions. Optical microscopy and SEM analyses indicate that the passive layers are compact and do not reveal fractures or cracks. XPS characterization of the colored passive layers reveals that their surface-chemical composition depends on the AC polarization voltage. The main constituents of the passive layers are Ti z+ , O 2- , and F - (z varies from 4 to 2 depending on the depth). Fluoride in the film originates form decomposition of NH 4 BF 4 and it accumulates at the inner metal/passive-film interface. XPS depth profiling shows that the higher the AC voltage applied, the thicker the passive film formed. Electrochemical properties of the colored Ti passive layers are determined by recording polarization curves in the -0.8 - 3.2 V, RHE, range and Tafel plots in the hydrogen evolution reaction (HER) region in 1.0 M aqueous H 2 SO 4 solution. The polarization curves show that the corrosion potential of the colored passive layers shifts towards less-negative potential indicating that they are more stable than Ti under the same conditions. The Tafel plots for the HER demonstrate that the passive layers have much higher activity than Ti towards the HER. The Tafel relations reveal new features that can be associated with the partial breakdown/decomposition of the passive layers and with H absorption. (author)

  4. EPA Region 2 Draft NPL Site Contamination Area Boundaries as of February 2007 GIS Layer [EPA.R2_NPL_CONTAMBND

    Data.gov (United States)

    U.S. Environmental Protection Agency — This layer represents the contamination boundaries of all NPL sites located in EPA Region Region 2 (New York, New Jersey, Puerto Rico and the U.S. Virgin Islands)....

  5. Observations of the atmospheric boundary layer height over Abu Dhabi, United Arab Emirates: Investigating boundary layer climatology in arid regions

    Science.gov (United States)

    Marzooqi, Mohamed Al; Basha, Ghouse; Ouarda, Taha B. M. J.; Armstrong, Peter; Molini, Annalisa

    2014-05-01

    Strong sensible heat fluxes and deep turbulent mixing - together with marked dustiness and a low substrate water content - represent a characteristic signature in the boundary layer over hot deserts, resulting in "thicker" mixing layers and peculiar optical properties. Beside these main features however, desert ABLs present extremely complex local structures that have been scarcely addressed in the literature, and whose understanding is essential in modeling processes such as the transport of dust and pollutants, and turbulent fluxes of momentum, heat and water vapor in hyper-arid regions. In this study, we analyze a continuous record of observations of the atmospheric boundary layer (ABL) height from a single lens LiDAR ceilometer operated at Masdar Institute Field Station (24.4oN, 54.6o E, Abu Dhabi, United Arab Emirates), starting March 2013. We compare different methods for the estimation of the ABL height from Ceilometer data such as, classic variance-, gradient-, log gradient- and second derivation-methods as well as recently developed techniques such as the Bayesian Method and Wavelet covariance transform. Our goal is to select the most suited technique for describing the climatology of the ABL in desert environments. Comparison of our results with radiosonde observations collected at the nearby airport of Abu Dhabi indicate that the WCT and the Bayesian method are the most suitable tools to accurately identify the ABL height in all weather conditions. These two methods are used for the definition of diurnal and seasonal climatologies of the boundary layer conditional to different atmospheric stability classes.

  6. The effect of asymmetric barrier layers in the waveguide region on power characteristics of QW lasers

    DEFF Research Database (Denmark)

    Zubov, F. I.; Zhukov, A. E.; Shernyakov, Yu M.

    2015-01-01

    Current-voltage and light-current characteristics of quantum-well lasers have been studied at high drive currents. The introduction of asymmetric barrier layers adjacent to the active region caused a significant suppression of the nonlinearity in the light-current characteristic and an increase...

  7. The atmospheric boundary layer over land and sea: Focus on the off-shore Southern Baltic and Southern North Sea region

    DEFF Research Database (Denmark)

    Larsen, Søren Ejling

    Lecture notes for a short course on the ideal atmospheric boundary layer and its characteristics for different types of real boundary layers, aiming at a discussion of the coastal conditions at the Southern Baltic and North Sea region. The notes are aimed at young scientists (e.g. PhD students......) that study the physics of the atmospheric boundary layer with the purpose of applying this knowledge for remote sensing techniques within offshore wind energy....

  8. Enhancement of early cervical cancer diagnosis with epithelial layer analysis of fluorescence lifetime images.

    Directory of Open Access Journals (Sweden)

    Jun Gu

    Full Text Available This work reports the use of layer analysis to aid the fluorescence lifetime diagnosis of cervical intraepithelial neoplasia (CIN from H&E stained cervical tissue sections. The mean and standard deviation of lifetimes in single region of interest (ROI of cervical epithelium were previously shown to correlate to the gold standard histopathological classification of early cervical cancer. These previously defined single ROIs were evenly divided into layers for analysis. A 10-layer model revealed a steady increase in fluorescence lifetime from the inner to the outer epithelial layers of healthy tissue sections, suggesting a close association with cellular maturity. The shorter lifetime and minimal lifetime increase towards the epithelial surface of CIN-affected regions are in good agreement with the absence of cellular maturation in CIN. Mean layer lifetimes in the top-half cervical epithelium were used as feature vectors for extreme learning machine (ELM classifier discriminations. It was found that the proposed layer analysis technique greatly improves the sensitivity and specificity to 94.6% and 84.3%, respectively, which can better supplement the traditional gold standard cervical histopathological examinations.

  9. Borneo stalagmites reveal climatic excursions associated with Toba ash layers prior to Greenland Stadial 20

    Science.gov (United States)

    Cobb, K. M.; Orland, I. J.; Carolin, S.; Adkins, J. F.; Valley, J. W.; Jersild, A.; LeGrande, A. N.; Colose, C.

    2017-12-01

    The Toba super-eruption occurred in close association with an abrupt climate transition from Greenland Interstadial (GI-) 20 to Greenland Stadial (GS-) 20, roughly 74 thousand years ago. However, recent attempts to characterize either the regional or global climate response to Toba have been limited by a lack of age control, geographic proximity, and/or convincing marker of the major eruption in most high-resolution paleoclimate archives. Here, we use a suite of micro-scale analytical techniques to evaluate the oxygen isotopic and geochemical composition of multiple stalagmites that grew across the Toba interval in Gunung Mulu National Park, northern Borneo. New timeseries of stalagmite d18O at 50-micron scales across the Toba horizon revleal a large (>1‰), rapid (<200 yr) increase in d18O values within age-error of the 40Ar/39Ar age of the Youngest Toba Tuff (73.9±0.6 ky BP; Storey et al., 2012). We supplement these traditional mass spectrometric measurements with d18O timeseries made on 9-micron spots using the WiscSIMS CAMECA ims 1280 ion microprobe in time-transgressive segments across the Toba horizon in two well-dated stalagmites previously published in Carolin et al., 2013 and Caroline et al., 2014. The SIMS d18O data reveal high-frequency d18O excursions of +2 and -2 per mil during the transition from GI-20 (warm conditions) to Greenland Stadial GS-20 (cool conditions), suggesting that this period was characterized by large fluctuations in regional hydroclimate in the western tropical Pacific, with potentially profound impacts on global atmospheric circulation. We also present results from synchrotron analyses of ash-related elements (S, P, Si, and Al) to resolve the number and relative magnitude of Toba-related eruptions as recorded in several different stalagmites from Borneo, where ash layers likely exceeded 2cm on the overlying terrain. Together, these results indicate that large, rapid ( 10yr-long) environmental changes with marked effects on both

  10. Modelling internal boundary-layer development in a region with a complex coastline

    DEFF Research Database (Denmark)

    Batchvarova, E.; Cai, X.; Gryning, Sven-Erik

    1999-01-01

    , and the Colorado State University Regional Atmospheric Modelling System (CSU-RAMS) are tested by comparison with data gathered during a field study (called Pacific '93) of photochemical pollution in the Lower Fraser Valley of British Columbia, Canada. The data utilised here are drawn from tethered balloon flights......, free flying balloon ascents, and downlooking lidar operated from an aircraft flown at roughly 3500 m above sea level. Both models are found to represent the temporal and spatial development of the internal boundary-layer depth over the Lower Fraser Valley very well, and reproduce many of the finer...

  11. Premature Aging Phenotype in Mice Lacking High-Affinity Nicotinic Receptors: Region-Specific Changes in Layer V Pyramidal Cell Morphology.

    Science.gov (United States)

    Konsolaki, Eleni; Skaliora, Irini

    2015-08-01

    The mechanisms by which aging leads to alterations in brain structure and cognitive deficits are unclear. Α deficient cholinergic system has been implicated as one of the main factors that could confer a heightened vulnerability to the aging process, and mice lacking high-affinity nicotinic receptors (β2(-/-)) have been proposed as an animal model of accelerated cognitive aging. To date, however, age-related changes in neuronal microanatomy have not been studied in these mice. In the present study, we examine the neuronal structure of yellow fluorescent protein (YFP(+)) layer V neurons in 2 cytoarchitectonically distinct cortical regions in wild-type (WT) and β2(-/-) animals. We find that (1) substantial morphological differences exist between YFP(+) cells of the anterior cingulate cortex (ACC) and primary visual cortex (V1), in both genotypes; (2) in WT animals, ACC cells are more susceptible to aging compared with cells in V1; and (3) β2 deletion is associated with a regionally and temporally specific increase in vulnerability to aging. ACC cells exhibit a prematurely aged phenotype already at 4-6 months, whereas V1 cells are spared in adulthood but strongly affected in old animals. Collectively, our data reveal region-specific synergistic effects of aging and genotype and suggest distinct vulnerabilities in V1 and ACC neurons. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  12. Solar wind energy transfer regions inside the dayside magnetopause

    International Nuclear Information System (INIS)

    Lundin, R.; Dubinin, E.

    1984-01-01

    PROGNOZ-7 high temporal resolution measurements of the ion composition and hot plasma distribution in the dayside high latitude boundary layer near noon have revealed that magnetosheath plasma may penetrate the dayside magnetopause and form high density, high β, magnetosheath-like regions inside the magnetopause. From these measurements it is demonstrated that the magnetosheath injection regions most probably play an important role in transferring solar wind energy into the magnetosphere. The transfer regions are characterized by a strong perpendicular flow towards dawn or dusk (depending on local time) but are also observed to expand rapidly along the boundary field lines. This increased flow component transverse to the local magnetic field corresponds to a predominantly radial electric field of up to several mV m -1 , which indicates that the injected magnetosheath plasma causes an enhanced polarization of the boundary layer. Polarization of the boundary layer can therefore be considered a result of a local MHD-process where magnetosheath plasma excess momentum is converted into electromagnetic energy (electric field), i.e. there is an MHD-generator. It was observed that the boundary layer is charged up to tens of kilovolts, a potential which may be highly variable on e.g. the presence of a momentum exchange by the energy transfer regions. (author)

  13. Analysis of Nb3Sn surface layers for superconducting radio frequency cavity applications

    Science.gov (United States)

    Becker, Chaoyue; Posen, Sam; Groll, Nickolas; Cook, Russell; Schlepütz, Christian M.; Hall, Daniel Leslie; Liepe, Matthias; Pellin, Michael; Zasadzinski, John; Proslier, Thomas

    2015-02-01

    We present an analysis of Nb3Sn surface layers grown on a bulk Niobium (Nb) coupon prepared at the same time and by the same vapor diffusion process used to make Nb3Sn coatings on 1.3 GHz Nb cavities. Tunneling spectroscopy reveals a well-developed, homogeneous superconducting density of states at the surface with a gap value distribution centered around 2.7 ± 0.4 meV and superconducting critical temperatures (Tc) up to 16.3 K. Scanning transmission electron microscopy performed on cross sections of the sample's surface region shows an ˜2 μm thick Nb3Sn surface layer. The elemental composition map exhibits a Nb:Sn ratio of 3:1 and reveals the presence of buried sub-stoichiometric regions that have a ratio of 5:1. Synchrotron x-ray diffraction experiments indicate a polycrystalline Nb3Sn film and confirm the presence of Nb rich regions that occupy about a third of the coating volume. These low Tc regions could play an important role in the dissipation mechanisms occurring during RF tests of Nb3Sn-coated Nb cavities and open the way for further improving a very promising alternative to pure Nb cavities for particle accelerators.

  14. Analysis of Nb3Sn surface layers for superconducting radio frequency cavity applications

    International Nuclear Information System (INIS)

    Becker, Chaoyue; Posen, Sam; Hall, Daniel Leslie; Groll, Nickolas; Proslier, Thomas; Cook, Russell; Schlepütz, Christian M.; Liepe, Matthias; Pellin, Michael; Zasadzinski, John

    2015-01-01

    We present an analysis of Nb 3 Sn surface layers grown on a bulk Niobium (Nb) coupon prepared at the same time and by the same vapor diffusion process used to make Nb 3 Sn coatings on 1.3 GHz Nb cavities. Tunneling spectroscopy reveals a well-developed, homogeneous superconducting density of states at the surface with a gap value distribution centered around 2.7 ± 0.4 meV and superconducting critical temperatures (T c ) up to 16.3 K. Scanning transmission electron microscopy performed on cross sections of the sample's surface region shows an ∼2 μm thick Nb 3 Sn surface layer. The elemental composition map exhibits a Nb:Sn ratio of 3:1 and reveals the presence of buried sub-stoichiometric regions that have a ratio of 5:1. Synchrotron x-ray diffraction experiments indicate a polycrystalline Nb 3 Sn film and confirm the presence of Nb rich regions that occupy about a third of the coating volume. These low T c regions could play an important role in the dissipation mechanisms occurring during RF tests of Nb 3 Sn-coated Nb cavities and open the way for further improving a very promising alternative to pure Nb cavities for particle accelerators

  15. Identification of the Viscous Superlayer on the Low-Speed Side of a Single-Stream Shear Layer

    Science.gov (United States)

    Foss, John; Peabody, Jason

    2010-11-01

    Image pairs (elevation/plan views) have been acquired of a smoke streakline originating in the irrotational region on the low-speed side of a high Re single-stream shear layer of Morris and Foss (2003). The viscous superlayer (VSL) is identified as the terminus of the streak; 1800 such images provide VSL position statistics. Hot-wire data acquired concurrently at the shear layer edge and interior are used to investigate the relationship between these velocity magnitudes and the large-scale motions. Distinctive features (plumes) along the streakline are tracked between images to provide discrete irrotational region velocity magnitudes and material trajectories. A non-diffusive marker, introduced in the separating (high speed) boundary layer and imaged at x/θo=352, has revealed an unexpected bias in the streak-defined VSL locations. The interpretation of this bias clarifies the induced flow patterns in the entrainment region. The observations are consistent with a conception of the large-scale shear layer motions as "billows" of vortical fluid separated by re-entrant "wedges" of irrotational fluid, per Phillips (1972). Morris, S.C. and Foss, J.F. (2003). "Turbulent Boundary Layer to Single Stream Shear Layer: The Transition Region." Journal of Fluid Mechanics. Vol. 494, pp. 187-221. Phillips, O. M. (1972). "The Entrainment Interface." Journal of Fluid Mechanics. Vol. 51, pp. 97-118.

  16. Formation of double layers

    International Nuclear Information System (INIS)

    Leung, P.; Wong, A.Y.; Quon, B.H.

    1981-01-01

    Experiments on both stationary and propagating double layers and a related analytical model are described. Stationary double layers were produced in a multiple plasma device, in which an electron drift current was present. An investigation of the plasma parameters for the stable double layer condition is described. The particle distribution in the stable double layer establishes a potential profile, which creates electron and ion beams that excite plasma instabilities. The measured characteristics of the instabilities are consistent with the existence of the double layer. Propagating double layers are formed when the initial electron drift current is large. Ths slopes of the transition region increase as they propagate. A physical model for the formation of a double layer in the experimental device is described. This model explains the formation of the low potential region on the basis of the space charge. This space charge is created by the electron drift current. The model also accounts for the role of ions in double layer formation and explains the formation of moving double layers. (Auth.)

  17. Computations of intermittent transport in scrape-off layer plasmas

    DEFF Research Database (Denmark)

    Garcia, O.E.; Naulin, V.; Nielsen, A.H.

    2004-01-01

    in the form of blobs. These structures propagate far into the scrape-off layer where they are dissipated due to transport along open magnetic field lines. From single-point recordings it is shown that the blobs have asymmetric conditional wave forms and lead to positively skewed and flattened probability......Two-dimensional fluid simulations of interchange turbulence for geometry and parameters relevant for the scrape-off layer of magnetized plasmas are presented. The computations, which have distinct plasma production and loss regions, reveal bursty ejection of particles and heat from the bulk plasma...... distribution functions. The radial propagation velocity may reach one-tenth of the sound speed. These results are in excellent agreement with recent experimental measurements....

  18. Evaluation of chemical and/or mechanical treatments of the smear layer as revealed by scanning electron microscopy - a blind comparative study

    Directory of Open Access Journals (Sweden)

    LUZ Maria Aparecida Alves de Cerqueira

    2000-01-01

    Full Text Available A blind comparative study of chemical and/or mechanical treatments of the smear layer, according to scanning electron microscopy images, was carried out. The effect of the treatments was analyzed on the smear layer of mesio-occlusodistal cavity walls prepared in vitro in human third molars. The agents used were air/water spray, 37% phosphoric acid, 5% tannic acid, biologic detergent, 0.5% sodium hypochlorite, and enamel hatchet alone or in association with the previous agents. Electron micrographs were evaluated by three professionals according to the degree of visualization of underlying dentin or enamel. Phosphoric acid received the highest scores due to the complete removal of the smear layer. However, statistical analyses revealed diverse performances of non or slightly demineralizing agents, according to the cavity walls in dentin, while there was equivalent effect on the enamel of gingival walls.

  19. Is the boundary layer of an ionic liquid equally lubricating at higher temperature?

    Science.gov (United States)

    Hjalmarsson, Nicklas; Atkin, Rob; Rutland, Mark W

    2016-04-07

    Atomic force microscopy has been used to study the effect of temperature on normal forces and friction for the room temperature ionic liquid (IL) ethylammonium nitrate (EAN), confined between mica and a silica colloid probe at 25 °C, 50 °C, and 80 °C. Force curves revealed a strong fluid dynamic influence at room temperature, which was greatly reduced at elevated temperatures due to the reduced liquid viscosity. A fluid dynamic analysis reveals that bulk viscosity is manifested at large separation but that EAN displays a nonzero slip, indicating a region of different viscosity near the surface. At high temperatures, the reduction in fluid dynamic force reveals step-like force curves, similar to those found at room temperature using much lower scan rates. The ionic liquid boundary layer remains adsorbed to the solid surface even at high temperature, which provides a mechanism for lubrication when fluid dynamic lubrication is strongly reduced. The friction data reveals a decrease in absolute friction force with increasing temperature, which is associated with increased thermal motion and reduced viscosity of the near surface layers but, consistent with the normal force data, boundary layer lubrication was unaffected. The implications for ILs as lubricants are discussed in terms of the behaviour of this well characterised system.

  20. Turbulent fluxes in atmospheric boundary layer of a semi-arid region of N-E Brazil

    International Nuclear Information System (INIS)

    Patel, S. R.; De Fatima Correia, M.; Da Silva, E. M.; Costa, A. M. N.

    2004-01-01

    The preliminary results of the Experiment 'Experimento de Microfisica de Nuvens-EmfiN' (Experiment of microphysics of clouds) conducted by Universidade Estatual de Ceara-UECE at Fortaleza, a semi-arid region of N-E Brazil, are presented. The mean kinematic fluxes of sensible heat and water vapor of the surface boundary layer are estimated by the thermodynamic energy and water vapor conservation equations; and by the Monin-Obukhov similarity theory. The results of the two methods are in good agreement. It is shown that in the absence of sophisticated fast-response turbulence instrumentation and wind data the conservations equations methods are better option for estimation of heat and water vapor fluxes. Further they are useful to study the turbulent fluxes in inhomogeneous condition in time like early morning and late evening boundary layer transitions

  1. Surface photovoltage studies of p-type AlGaN layers after reactive-ion etching

    Science.gov (United States)

    McNamara, J. D.; Phumisithikul, K. L.; Baski, A. A.; Marini, J.; Shahedipour-Sandvik, F.; Das, S.; Reshchikov, M. A.

    2016-10-01

    The surface photovoltage (SPV) technique was used to study the surface and electrical properties of Mg-doped, p-type AlxGa1-xN (0.06 GaN:Mg thin films and from the predictions of a thermionic model for the SPV behavior. In particular, the SPV of the p-AlGaN:Mg layers exhibited slower-than-expected transients under ultraviolet illumination and delayed restoration to the initial dark value. The slow transients and delayed restorations can be attributed to a defective surface region which interferes with normal thermionic processes. The top 45 nm of the p-AlGaN:Mg layer was etched using a reactive-ion etch which caused the SPV behavior to be substantially different. From this study, it can be concluded that a defective, near-surface region is inhibiting the change in positive surface charge by allowing tunneling or hopping conductivity of holes from the bulk to the surface, or by the trapping of electrons traveling to the surface by a high concentration of defects in the near-surface region. Etching removes the defective layer and reveals a region of presumably higher quality, as evidenced by substantial changes in the SPV behavior.

  2. Diblock Copolymer/Layered Silicate Nanocomposite Thin Film Stability

    Science.gov (United States)

    Limary, Ratchana; Green, Peter

    2000-03-01

    The stability of thin film symmetric diblock copolymers blended with layered silicate nanocomposites were examined using a combination of optical microscopy, atomic force microscopy (AFM), and X-ray diffraction (XRD). Two cases were examined PS-b-PMMA (polystyrene-b-polymethylacrylate) blended with montmorillonite stoichiometrically loaded with alkyl ammonium ions, OLS(S), and PS-b-PMMA blended with montmorillonite loaded with excess alkyl ammonium ions, OLS(E). XRD spectra show an increase in the gallery spacing of the OLSs, indicating that the copolymer chains have intercalated the layered silicates. AFM images reveal a distinct difference between the two nanocomposite thin films: regions in the vicinity of OLS(S) aggregates were depleted of material, while in the vicinity of OLS(E) aggregates, dewetting of the substrate occurred. We show that the stability of the copolymer/OLS nanocomposite films is determined by the enthalpic driving force associated with intercalation of the copolymer chains into the galleries of the modified OLS layers and by the substrate/organic modifier interactions.

  3. Equatorial E Region Electric Fields and Sporadic E Layer Responses to the Recovery Phase of the November 2004 Geomagnetic Storm

    Science.gov (United States)

    Moro, J.; Resende, L. C. A.; Denardini, C. M.; Xu, J.; Batista, I. S.; Andrioli, V. F.; Carrasco, A. J.; Batista, P. P.; Schuch, N. J.

    2017-12-01

    Equatorial E region electric fields (EEFs) inferred from coherent radar data, sporadic-E (Es) layers observed from a digital ionosonde data, and modeling results are used to study the responses of the equatorial E region over São Luís (SLZ, 2.3°S, 44.2°W, -7° dip angle), Brazil, during the super storm of November 2004. The EEF is presented in terms of the zonal (Ey) and vertical (Ez) components in order to analyze the corresponding characteristics of different types of Es seen in ionograms and simulated with the E region ionospheric model. We bring out the variabilities of Ey and Ez components with storm time changes in the equatorial E region. In addition, some aspects of the electric fields and Es behavior in three cases of weak, very weak, and strong Type II occurrences during the recovery phase of the geomagnetic storm are discussed. The connection between the enhanced occurrence and suppressions of the Type II irregularities and the q-type Es (Esq) controlled by electric fields, with the development or disruption of the blanketing sporadic E (Esb) layers produced by wind shear mechanism, is also presented. The mutual presence of Esq along with the Esb occurrences is a clear indicator of the secular drift of the magnetic equator and hence that of the equatorial electrojet (EEJ) over SLZ. The results show evidence about the EEJ and Es layer electrodynamics and coupling during geomagnetic disturbance time electric fields.

  4. Questing and the application for silicon based ternary compound within ultra-thin layer of SIS intermediate region

    International Nuclear Information System (INIS)

    Chen, Shumin; Gao, Ming; Wan, Yazhou; Du, Huiwei; Li, Yong; Ma, Zhongquan

    2016-01-01

    Highlights: • A new kind of functional material with plasticity of dielectric was obtained. • Powerful characterization methods was exploited to determine this ultra-thin layer. • The electronic structures and properties of this intermediate layer were analyzed. • A potential application of this structure were investigated. - Abstract: A silicon based ternary compound was supposed to be solid synthesized with In, Si and O elements by magnetron sputtering of indium tin oxide target (ITO) onto crystal silicon substrate at 250 °C. To make clear the configuration of the intermediate region, a potential method to obtain the chemical bonding of Si with other existing elements was exploited by X-ray photoelectron spectroscopy (XPS) instrument combined with other assisted techniques. The phase composition and solid structure of the interfacial region between ITO and Si substrate were investigated by X-ray diffraction (XRD) and high resolution cross sectional transmission electron microscope (HR-TEM). A photovoltaic device with structure of Al/Ag/ITO/SiOx/p-Si/Al was assembled by depositing ITO films onto the p-Si substrate by using magnetron sputtering. The new matter has been assumed to be a buffer layer for semiconductor-insulator-semiconductor (SIS) photovoltaic device and plays critical role for the promotion of optoelectronic conversion performance from the view point of device physics.

  5. Questing and the application for silicon based ternary compound within ultra-thin layer of SIS intermediate region

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shumin; Gao, Ming; Wan, Yazhou; Du, Huiwei; Li, Yong [SHU-SolarE R& D Lab, Department of Physics, Shanghai University, Shanghai 200444 (China); Ma, Zhongquan, E-mail: zqma@shu.edu.cn [SHU-SolarE R& D Lab, Department of Physics, Shanghai University, Shanghai 200444 (China); Instrumental Analysis & Research Center, Shanghai University, Shanghai 200444 (China)

    2016-12-01

    Highlights: • A new kind of functional material with plasticity of dielectric was obtained. • Powerful characterization methods was exploited to determine this ultra-thin layer. • The electronic structures and properties of this intermediate layer were analyzed. • A potential application of this structure were investigated. - Abstract: A silicon based ternary compound was supposed to be solid synthesized with In, Si and O elements by magnetron sputtering of indium tin oxide target (ITO) onto crystal silicon substrate at 250 °C. To make clear the configuration of the intermediate region, a potential method to obtain the chemical bonding of Si with other existing elements was exploited by X-ray photoelectron spectroscopy (XPS) instrument combined with other assisted techniques. The phase composition and solid structure of the interfacial region between ITO and Si substrate were investigated by X-ray diffraction (XRD) and high resolution cross sectional transmission electron microscope (HR-TEM). A photovoltaic device with structure of Al/Ag/ITO/SiOx/p-Si/Al was assembled by depositing ITO films onto the p-Si substrate by using magnetron sputtering. The new matter has been assumed to be a buffer layer for semiconductor-insulator-semiconductor (SIS) photovoltaic device and plays critical role for the promotion of optoelectronic conversion performance from the view point of device physics.

  6. Region 7 Significant Ecological Resource Areas (ECO_RES.SIG_REGIONS)

    Data.gov (United States)

    U.S. Environmental Protection Agency — SIG_REGIONS is a boundary layer that displays Region 7's Significant Ecological Resource Areas. This layer represents large areas within which different ecosystem...

  7. Mixed layer depth calculation in deep convection regions in ocean numerical models

    Science.gov (United States)

    Courtois, Peggy; Hu, Xianmin; Pennelly, Clark; Spence, Paul; Myers, Paul G.

    2017-12-01

    Mixed Layer Depths (MLDs) diagnosed by conventional numerical models are generally based on a density difference with the surface (e.g., 0.01 kg.m-3). However, the temperature-salinity compensation and the lack of vertical resolution contribute to over-estimated MLD, especially in regions of deep convection. In the present work, we examined the diagnostic MLD, associated with the deep convection of the Labrador Sea Water (LSW), calculated with a simple density difference criterion. The over-estimated MLD led us to develop a new tool, based on an observational approach, to recalculate MLD from model output. We used an eddy-permitting, 1/12° regional configuration of the Nucleus for European Modelling of the Ocean (NEMO) to test and discuss our newly defined MLD. We compared our new MLD with that from observations, and we showed a major improvement with our new algorithm. To show the new MLD is not dependent on a single model and its horizontal resolution, we extended our analysis to include 1/4° eddy-permitting simulations, and simulations using the Modular Ocean Model (MOM) model.

  8. Largely Tunable Band Structures of Few-Layer InSe by Uniaxial Strain.

    Science.gov (United States)

    Song, Chaoyu; Fan, Fengren; Xuan, Ningning; Huang, Shenyang; Zhang, Guowei; Wang, Chong; Sun, Zhengzong; Wu, Hua; Yan, Hugen

    2018-01-31

    Because of the strong quantum confinement effect, few-layer γ-InSe exhibits a layer-dependent band gap, spanning the visible and near infrared regions, and thus recently has been drawing tremendous attention. As a two-dimensional material, the mechanical flexibility provides an additional tuning knob for the electronic structures. Here, for the first time, we engineer the band structures of few-layer and bulk-like InSe by uniaxial tensile strain and observe a salient shift of photoluminescence peaks. The shift rate of the optical gap is approximately 90-100 meV per 1% strain for four- to eight-layer samples, which is much larger than that for the widely studied MoS 2 monolayer. Density functional theory calculations well reproduce the observed layer-dependent band gaps and the strain effect and reveal that the shift rate decreases with the increasing layer number for few-layer InSe. Our study demonstrates that InSe is a very versatile two-dimensional electronic and optoelectronic material, which is suitable for tunable light emitters, photodetectors, and other optoelectronic devices.

  9. RNA-Seq reveals seven promising candidate genes affecting the proportion of thick egg albumen in layer-type chickens.

    Science.gov (United States)

    Wan, Yi; Jin, Sihua; Ma, Chendong; Wang, Zhicheng; Fang, Qi; Jiang, Runshen

    2017-12-22

    Eggs with a much higher proportion of thick albumen are preferred in the layer industry, as they are favoured by consumers. However, the genetic factors affecting the thick egg albumen trait have not been elucidated. Using RNA sequencing, we explored the magnum transcriptome in 9 Rhode Island white layers: four layers with phenotypes of extremely high ratios of thick to thin albumen (high thick albumen, HTA) and five with extremely low ratios (low thick albumen, LTA). A total of 220 genes were differentially expressed, among which 150 genes were up-regulated and 70 were down-regulated in the HTA group compared with the LTA group. Gene Ontology (GO) analysis revealed that the up-regulated genes in HTA were mainly involved in a wide range of regulatory functions. In addition, a large number of these genes were related to glycosphingolipid biosynthesis, focal adhesion, ECM-receptor interactions and cytokine-cytokine receptor interactions. Based on functional analysis, ST3GAL4, FUT4, ITGA2, SDC3, PRLR, CDH4 and GALNT9 were identified as promising candidate genes for thick albumen synthesis and metabolism during egg formation. These results provide new insights into the molecular mechanisms of egg albumen traits and may contribute to future breeding strategies that optimise the proportion of thick egg albumen.

  10. Regional atmospheric budgets of reduced nitrogen over the British isles assessed using a multi-layer atmospheric transport model

    NARCIS (Netherlands)

    Fournier, N.; Tang, Y.S.; Dragosits, U.; Kluizenaar, Y.de; Sutton, M.A.

    2005-01-01

    Atmospheric budgets of reduced nitrogen for the major political regions of the British Isles are investigated with a multi-layer atmospheric transport model. The model is validated against measurements of NH3 concentration and is developed to provide atmospheric budgets for defined subdomains of the

  11. Dynamic clustering scheme based on the coordination of management and control in multi-layer and multi-region intelligent optical network

    Science.gov (United States)

    Niu, Xiaoliang; Yuan, Fen; Huang, Shanguo; Guo, Bingli; Gu, Wanyi

    2011-12-01

    A Dynamic clustering scheme based on coordination of management and control is proposed to reduce network congestion rate and improve the blocking performance of hierarchical routing in Multi-layer and Multi-region intelligent optical network. Its implement relies on mobile agent (MA) technology, which has the advantages of efficiency, flexibility, functional and scalability. The paper's major contribution is to adjust dynamically domain when the performance of working network isn't in ideal status. And the incorporation of centralized NMS and distributed MA control technology migrate computing process to control plane node which releases the burden of NMS and improves process efficiently. Experiments are conducted on Multi-layer and multi-region Simulation Platform for Optical Network (MSPON) to assess the performance of the scheme.

  12. Structure of the low-latitude boundary layer

    International Nuclear Information System (INIS)

    Sckopke, N.; Paschmann, G.; Haerendel, G.; Sonnerup, B.U.O.; Bame, S.J.; Forbes, T.G.; Hones, E.W. Jr.; Russell, C.T.

    1981-01-01

    Observations at high temporal resolution of the frontside magnetopause and plasma boundary layer, made with the Los Alamos Scientific Laboratory/Max-Planck-Institut, Institut fuer Extraterrestrische Physik, fast plasma analyzer on board the Isee 1 and 2 spacecraft, have revealed a complex quasi-periodic structure of some of the observed boundary layers: cool tailward streaming boundary layer plasma is seen intermittently, with intervening periods of hot tenuous plasma which has properties similar to the magnetospheric population. While individual encounters with the boundary layer plasma last only a few minutes, the total observation time may extend over 1 hour or more. One such crossing, at 0800 hours local time and 40 0 northern GSM latitude, is examined in detail, including a quantitative comparison of the boundary layer entry and exit times of the two spacecraft. The data are found to be compatible with a boundary layer that is always attached to the magnetopause but where the layer thickness has a large-scale spatial modulation pattern which travels tailward past the spacecraft. Included are periods when the thickness is essentially zero and others when it is of the order of 1 R/sub E/. The duration of these periods is highly variable but is typically in the range of 2--5 min, corresponding to a distance along the magnetopause of the order of 3--8 R/sub E/. The observed boundary layer features include a steep density gradient at the magnetopause, with an approximately constant boundary layer plasma density amounting to about 25% of the magnetosheath density, and a second abrupt density decrease at the inner edge of the layer. It also appears that the purely magnetospheric plasma is ocassionally separated from the boundary layer by a halo region in which the plasma density is somewhat higher, and the temperature somewhat lower, than in the magnetosphere. A tentative model is proposed

  13. More evidence for a planetary wave link with midlatitude E region coherent backscatter and sporadic E layers

    Directory of Open Access Journals (Sweden)

    K. Schlegel

    Full Text Available Measurements of midlatitude E region coherent backscatter obtained during four summers with SESCAT, a 50 MHz Doppler system operating in Crete, Greece, and concurrent ionosonde recordings from the same ionospheric volume obtained with a CADI for one of these summers, are used to analyse the long-term variability in echo and Es occurrence. Echo and Es layer occurrences, computed in percent of time over a 12-h nighttime interval, take the form of time sequences. Linear power spectrum analysis shows that there are dominant spectral peaks in the range of 2–9 days, the most commonly observed periods appearing in two preferential bands, of 2–3 days and 4–7 days. No connection with geomagnetic activity was found. The characteristics of these periodicities compare well with similar properties of planetary waves, which suggests the possibility that planetary waves are responsible for the observed long-term periodicities. These findings indicate also a likely close relation between planetary wave (PW activity and the well known but not well understood seasonal Es dependence. To test the PW postulation, we used simultaneous neutral wind data from the mesopause region around 95 km, measured from Collm, Germany. Direct comparison of the long-term periodicities in echo and Es layer occurrence with those in the neutral wind show some reasonable agreement. This new evidence, although not fully conclusive, is the first direct indication in favour of a planetary wave role on the unstable midlatitude E region ionosphere. Our results suggest that planetary waves observation is a viable option and a new element into the physics of midlatitude Es layers that needs to be considered and investigated.Key words: Ionosphere (ionosphere irregularities; mid-latitude ionosphere – Meteorology and atmospheric dynamics (waves and tides

  14. Single-layer ZnMN2 (M = Si, Ge, Sn) zinc nitrides as promising photocatalysts.

    Science.gov (United States)

    Bai, Yujie; Luo, Gaixia; Meng, Lijuan; Zhang, Qinfang; Xu, Ning; Zhang, Haiyang; Wu, Xiuqiang; Kong, Fanjie; Wang, Baolin

    2018-05-30

    Searching for two-dimensional semiconductor materials that are suitable for visible-light photocatalytic water splitting provides a sustainable solution to deal with the future energy crisis and environmental problems. Herein, based on first-principles calculations, single-layer ZnMN2 (M = Si, Ge, Sn) zinc nitrides are proposed as efficient photocatalysts for water splitting. Stability analyses show that the single-layer ZnMN2 zinc nitrides exhibit energetic and dynamical stability. The electronic properties reveal that all of the single-layer ZnMN2 zinc nitrides are semiconductors. Interestingly, single-layer ZnSnN2 is a direct band gap semiconductor with a desirable band gap (1.74 eV), and the optical adsorption spectrum confirms its optical absorption in the visible light region. The hydrogen evolution reaction (HER) calculations show that the catalytic activity for single-layer ZnMN2 (M = Ge, Sn) is better than that of single-layer ZnSiN2. Furthermore, the band gaps and band edge positions for the single-layer ZnMN2 zinc nitrides can be effectively tuned by biaxial strain. Especially, single-layer ZnGeN2 can be effectively tuned to match better with the redox potentials of water and enhance the light absorption in the visible light region at a tensile strain of 5%, which is confirmed by the corresponding optical absorption spectrum. Our results provide guidance for experimental synthesis efforts and future searches for single-layer materials suitable for photocatalytic water splitting.

  15. Sporadic potassium layers and their connection to sporadic E layers in the mesopause region at Beijing, China

    Directory of Open Access Journals (Sweden)

    Jing Jiao

    2017-06-01

    Full Text Available A double-laser beam lidar to measure potassium (K layer at Beijing (40.5° N, 116.2° E was successfully developed in 2010. The parameters of sporadic Ks layers and their distributions were given. The seasonal distribution of Ks occurrence frequency was obtained, with two maxima in July and January. The seasonal distributions of sporadic Es layer occurrence frequency over Beijing differ from those of Ks. However, the good correlation between Es and Ks in the case-by-case studies supports the mechanism of neutralization of metal ions in a descending Es layer.

  16. Laminar-specific distribution of zinc: evidence for presence of layer IV in forelimb motor cortex in the rat.

    Science.gov (United States)

    Alaverdashvili, Mariam; Hackett, Mark J; Pickering, Ingrid J; Paterson, Phyllis G

    2014-12-01

    The rat is the most widely studied pre-clinical model system of various neurological and neurodegenerative disorders affecting hand function. Although brain injury to the forelimb region of the motor cortex in rats mostly induces behavioral abnormalities in motor control of hand movements, behavioral deficits in the sensory-motor domain are also observed. This questions the prevailing view that cortical layer IV, a recipient of sensory information from the thalamus, is absent in rat motor cortex. Because zinc-containing neurons are generally not found in pathways that run from the thalamus, an absence of zinc (Zn) in a cortical layer would be suggestive of sensory input from the thalamus. To test this hypothesis, we used synchrotron micro X-ray fluorescence imaging to measure Zn distribution across cortical layers. Zn maps revealed a heterogeneous layered Zn distribution in primary and secondary motor cortices of the forelimb region in the adult rat. Two wider bands with elevated Zn content were separated by a narrow band having reduced Zn content, and this was evident in two rat strains. The Zn distribution pattern was comparable to that in sensorimotor cortex, which is known to contain a well demarcated layer IV. Juxtaposition of Zn maps and the images of brain stained for Nissl bodies revealed a "Zn valley" in primary motor cortex, apparently starting at the ventral border of pyramidal layer III and ending at the close vicinity of layer V. This finding indicates the presence of a conspicuous cortical layer between layers III and V, i.e. layer IV, the presence of which previously has been disputed. The results have implications for the use of rat models to investigate human brain function and neuropathology, such as after stroke. The presence of layer IV in the forelimb region of the motor cortex suggests that therapeutic interventions used in rat models of motor cortex injury should target functional abnormalities in both motor and sensory domains. The finding

  17. Analysis of Nb{sub 3}Sn surface layers for superconducting radio frequency cavity applications

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Chaoyue [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); High Energy Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Department of Physics, Illinois Institute of Technology, Chicago, Illinois 60616 (United States); Posen, Sam; Hall, Daniel Leslie [Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York 14853 (United States); Groll, Nickolas; Proslier, Thomas, E-mail: prolier@anl.gov [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); High Energy Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Cook, Russell [Nanoscience and Technology Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Schlepütz, Christian M. [X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Liepe, Matthias [Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York 14853 (United States); Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Pellin, Michael [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Zasadzinski, John [Department of Physics, Illinois Institute of Technology, Chicago, Illinois 60616 (United States)

    2015-02-23

    We present an analysis of Nb{sub 3}Sn surface layers grown on a bulk Niobium (Nb) coupon prepared at the same time and by the same vapor diffusion process used to make Nb{sub 3}Sn coatings on 1.3 GHz Nb cavities. Tunneling spectroscopy reveals a well-developed, homogeneous superconducting density of states at the surface with a gap value distribution centered around 2.7 ± 0.4 meV and superconducting critical temperatures (T{sub c}) up to 16.3 K. Scanning transmission electron microscopy performed on cross sections of the sample's surface region shows an ∼2 μm thick Nb{sub 3}Sn surface layer. The elemental composition map exhibits a Nb:Sn ratio of 3:1 and reveals the presence of buried sub-stoichiometric regions that have a ratio of 5:1. Synchrotron x-ray diffraction experiments indicate a polycrystalline Nb{sub 3}Sn film and confirm the presence of Nb rich regions that occupy about a third of the coating volume. These low T{sub c} regions could play an important role in the dissipation mechanisms occurring during RF tests of Nb{sub 3}Sn-coated Nb cavities and open the way for further improving a very promising alternative to pure Nb cavities for particle accelerators.

  18. Multi-layer structure of mid-latitude sporadic-E observed during the SEEK-2 campaign

    Directory of Open Access Journals (Sweden)

    T. Ono

    2005-10-01

    Full Text Available In the mid-latitude ionospheric region, sporadic-E layers (Es layers have often been observed, revealing multiple layers. The Es layers observed during the SEEK-2 rocket campaign showed double electron density peaks; namely, there are stable lower peaks and relatively unstable upper peaks. We examined the effects of wind shear and the electric fields on the generation of the multiple layer structure, in comparison with the electron density profile, the neutral wind, and the DC electric field observed by the S310 rocket experiments. The results showed that the neutral wind shear is mainly responsible for the generation of the lower layer, while the DC electric field makes a significant contribution to the formation of the upper layer. The difference between the lower and upper layers was also explained by the enhanced AC electric field observed at about 103–105 km altitude. The external DC electric field intensity is expected to be ~5 mV/m, which is enough to contribute to generate the Es layers in the ionosphere. Keywords. Ionosphere (Electric fields; Ionospheric irregularities, Mid-latitude ionosphere

  19. Mg/Al Ordering in Layered Double Hydroxides Revealed by Multinuclear NMR Spectroscopy

    DEFF Research Database (Denmark)

    Nielsen, Ulla Gro; Grey, Clare P.; Sideris, Paul J.

    2008-01-01

    The anion- exchange ability of layered double hydroxides ( LDHs) has been exploited to create materials for use in catalysis, drug delivery, and environmental remediation. The specific cation arrangements in the hydroxide layers of hydrotalcite- like LDHs, of general formula Mg1-x2+Alx3+OH2(Anion...

  20. On the modeling of electrical boundary layer (electrode layer) and ...

    Indian Academy of Sciences (India)

    In the first part of the paper, equations and methodology are discussed and in the second, we discuss results. 2. Methodology. In the atmospheric electricity, the earth's surface is one electrode and electrode layer or electrical boundary layer is a region near the surface of the earth in which profiles of atmospheric electrical.

  1. Low-temperature atomic layer epitaxy of AlN ultrathin films by layer-by-layer, in-situ atomic layer annealing.

    Science.gov (United States)

    Shih, Huan-Yu; Lee, Wei-Hao; Kao, Wei-Chung; Chuang, Yung-Chuan; Lin, Ray-Ming; Lin, Hsin-Chih; Shiojiri, Makoto; Chen, Miin-Jang

    2017-01-03

    Low-temperature epitaxial growth of AlN ultrathin films was realized by atomic layer deposition (ALD) together with the layer-by-layer, in-situ atomic layer annealing (ALA), instead of a high growth temperature which is needed in conventional epitaxial growth techniques. By applying the ALA with the Ar plasma treatment in each ALD cycle, the AlN thin film was converted dramatically from the amorphous phase to a single-crystalline epitaxial layer, at a low deposition temperature of 300 °C. The energy transferred from plasma not only provides the crystallization energy but also enhances the migration of adatoms and the removal of ligands, which significantly improve the crystallinity of the epitaxial layer. The X-ray diffraction reveals that the full width at half-maximum of the AlN (0002) rocking curve is only 144 arcsec in the AlN ultrathin epilayer with a thickness of only a few tens of nm. The high-resolution transmission electron microscopy also indicates the high-quality single-crystal hexagonal phase of the AlN epitaxial layer on the sapphire substrate. The result opens a window for further extension of the ALD applications from amorphous thin films to the high-quality low-temperature atomic layer epitaxy, which can be exploited in a variety of fields and applications in the near future.

  2. Electronic energy loss spectra from mono-layer to few layers of phosphorene

    International Nuclear Information System (INIS)

    Mohan, Brij; Thakur, Rajesh; Ahluwalia, P. K.

    2016-01-01

    Using first principles calculations, electronic and optical properties of few-layers phosphorene has been investigated. Electronic band structure show a moderate band gap of 0.9 eV in monolayer phosphorene which decreases with increasing number of layers. Optical properties of few-layers of phosphorene in infrared and visible region shows tunability with number of layers. Electron energy loss function has been plotted and huge red shift in plasmonic behaviours is found. These tunable electronic and optical properties of few-layers of phosphorene can be useful for the applications of optoelectronic devices.

  3. Electronic energy loss spectra from mono-layer to few layers of phosphorene

    Energy Technology Data Exchange (ETDEWEB)

    Mohan, Brij, E-mail: brijmohanhpu@yahoo.com; Thakur, Rajesh; Ahluwalia, P. K. [Department of Physics, Himachal Pradesh University, Shimla (HP) India 171005 (India)

    2016-05-23

    Using first principles calculations, electronic and optical properties of few-layers phosphorene has been investigated. Electronic band structure show a moderate band gap of 0.9 eV in monolayer phosphorene which decreases with increasing number of layers. Optical properties of few-layers of phosphorene in infrared and visible region shows tunability with number of layers. Electron energy loss function has been plotted and huge red shift in plasmonic behaviours is found. These tunable electronic and optical properties of few-layers of phosphorene can be useful for the applications of optoelectronic devices.

  4. A POROUS, LAYERED HELIOPAUSE

    Energy Technology Data Exchange (ETDEWEB)

    Swisdak, M.; Drake, J. F. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD 20742 (United States); Opher, M., E-mail: swisdak@umd.edu, E-mail: drake@umd.edu, E-mail: mopher@bu.edu [Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States)

    2013-09-01

    The picture of the heliopause (HP)-the boundary between the domains of the Sun and the local interstellar medium (LISM)-as a pristine interface with a large rotation in the magnetic field fails to describe recent Voyager 1 (V1) data. Magnetohydrodynamic (MHD) simulations of the global heliosphere reveal that the rotation angle of the magnetic field across the HP at V1 is small. Particle-in-cell simulations, based on cuts through the MHD model at V1's location, suggest that the sectored region of the heliosheath (HS) produces large-scale magnetic islands that reconnect with the interstellar magnetic field while mixing LISM and HS plasma. Cuts across the simulation reveal multiple, anti-correlated jumps in the number densities of LISM and HS particles, similar to those observed, at the magnetic separatrices. A model is presented, based on both the observations and simulations, of the HP as a porous, multi-layered structure threaded by magnetic fields. This model further suggests that contrary to the conclusions of recent papers, V1 has already crossed the HP.

  5. Impacts of synoptic condition and planetary boundary layer structure on the trans-boundary aerosol transport from Beijing-Tianjin-Hebei region to northeast China

    Science.gov (United States)

    Miao, Yucong; Guo, Jianping; Liu, Shuhua; Zhao, Chun; Li, Xiaolan; Zhang, Gen; Wei, Wei; Ma, Yanjun

    2018-05-01

    The northeastern China frequently experiences severe aerosol pollution in winter under unfavorable meteorological conditions. How and to what extent the meteorological factors affect the air quality there are not yet clearly understood. Thus, this study investigated the impacts of synoptic patterns on the aerosol transport and planetary boundary layer (PBL) structure in Shenyang from 1 to 3 December 2016, using surface observations, sounding measurements, satellite data, and three-dimensional simulations. Results showed that the aerosol pollution occurred in Shenyang was not only related to the local emissions, but also contributed by trans-boundary transport of aerosols from the Beiijng-Tianjin-Hebei (BTH) region. In the presence of the westerly and southwesterly synoptic winds, the aerosols emitted from BTH could be brought to Shenyang. From December 2 to 3, the aerosols emitted from BTH accounted for ∼20% of near-surface PM2.5 in Shenyang. In addition, the large-scale synoptic forcings could affect the vertical mixing of pollutants through modulating the PBL structure in Shenyang. The westerly and southwesterly synoptic winds not only brought the aerosols but also the warmer air masses from the southwest regions to Shenyang. The strong warm advections above PBL could enhance the already existing thermal inversion layers capping over PBL in Shenyang, leading to the suppressions of PBL. Both the trans-boundary transport of aerosols and the suppressions of PBL caused by the large-scale synoptic forcings should be partly responsible for the poor air quality in Shenyang, in addition to the high pollutant emissions. The present study revealed the physical mechanisms underlying the aerosol pollution in Shenyang, which has important implications for better forecasting and controlling the aerosols pollution.

  6. Effect of location on microstructure and mechanical properties of additive layer manufactured Inconel 625 using gas tungsten arc welding

    International Nuclear Information System (INIS)

    Wang, J.F.; Sun, Q.J.; Wang, H.; Liu, J.P.; Feng, J.C.

    2016-01-01

    Additive layer manufacturing (ALM), using gas tungsten arc welding (GTAW) as heat source, is a promising technology in producing Inconel 625 components due to significant cost savings, high deposition rate and convenience of processing. With the purpose of revealing how microstructure and mechanical properties are affected by the location within the manufactured wall component, the present study has been carried out. The manufactured Inconel 625 consists of cellular grains without secondary dendrites in the near-substrate region, columnar dendrites structure oriented upwards in the layer bands, followed by the transition from directional dendrites to equiaxed grain in the top region. With the increase in deposited height, segregation behavior of alloying elements Nb and Mo constantly strengthens with maximal evolution in the top region. The primary dendrite arm spacing has a well coherence with the content of Laves phase. The microhardness and tensile strength show obvious variation in different regions. The microhardness and tensile strength of near-substrate region are superior to that of layer bands and top region. The results are further explained in detail through the weld pool behavior and temperature field measurement.

  7. Effect of location on microstructure and mechanical properties of additive layer manufactured Inconel 625 using gas tungsten arc welding

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J.F. [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Shandong Provincial Key Laboratory of Special Welding Technology, Harbin Institute of Technology at Weihai, Weihai 264209 (China); Sun, Q.J., E-mail: qjsun@hit.edu.cn [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Shandong Provincial Key Laboratory of Special Welding Technology, Harbin Institute of Technology at Weihai, Weihai 264209 (China); Wang, H. [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Liu, J.P. [Shandong Provincial Key Laboratory of Special Welding Technology, Harbin Institute of Technology at Weihai, Weihai 264209 (China); China Nuclear Industry 23 Construction Co., Ltd., Beijing 101300 (China); Feng, J.C. [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Shandong Provincial Key Laboratory of Special Welding Technology, Harbin Institute of Technology at Weihai, Weihai 264209 (China)

    2016-10-31

    Additive layer manufacturing (ALM), using gas tungsten arc welding (GTAW) as heat source, is a promising technology in producing Inconel 625 components due to significant cost savings, high deposition rate and convenience of processing. With the purpose of revealing how microstructure and mechanical properties are affected by the location within the manufactured wall component, the present study has been carried out. The manufactured Inconel 625 consists of cellular grains without secondary dendrites in the near-substrate region, columnar dendrites structure oriented upwards in the layer bands, followed by the transition from directional dendrites to equiaxed grain in the top region. With the increase in deposited height, segregation behavior of alloying elements Nb and Mo constantly strengthens with maximal evolution in the top region. The primary dendrite arm spacing has a well coherence with the content of Laves phase. The microhardness and tensile strength show obvious variation in different regions. The microhardness and tensile strength of near-substrate region are superior to that of layer bands and top region. The results are further explained in detail through the weld pool behavior and temperature field measurement.

  8. Double layers above the aurora

    International Nuclear Information System (INIS)

    Temerin, M.; Mozer, F.S.

    1987-01-01

    Two different kinds of double layers were found in association with auroral precipitation. One of these is the so-called electrostatic shock, which is oriented at an oblique angle to the magnetic field in such a way that the perpendicular electric field is much larger than the parallel electric field. This type of double layer is often found at the edges of regions of upflowing ion beams and the direction of the electric fields in the shock points toward the ion beam. The potential drop through the shock can be several kV and is comparable to the total potential needed to produce auroral acceleration. Instabilities associated with the shock may generate obliquely propagating Alfven waves, which may accelerate electrons to produce flickering auroras. The flickering aurora provides evidence that the electrostatic shock may have large temporal fluctuations. The other kind of double layer is the small-amplitude double layer found in regions of upward flowing in beams, often in association with electrostatic ion cyclotron waves. The parallel and perpendicular electric fields in these structures are comparable in magnitude. The associated potentials are a few eV. Since many such double layers are found in regions of upward flowing ion beams, the combined potential drop through a set of these double layers can be substantial

  9. Circuit-wide Transcriptional Profiling Reveals Brain Region-Specific Gene Networks Regulating Depression Susceptibility.

    Science.gov (United States)

    Bagot, Rosemary C; Cates, Hannah M; Purushothaman, Immanuel; Lorsch, Zachary S; Walker, Deena M; Wang, Junshi; Huang, Xiaojie; Schlüter, Oliver M; Maze, Ian; Peña, Catherine J; Heller, Elizabeth A; Issler, Orna; Wang, Minghui; Song, Won-Min; Stein, Jason L; Liu, Xiaochuan; Doyle, Marie A; Scobie, Kimberly N; Sun, Hao Sheng; Neve, Rachael L; Geschwind, Daniel; Dong, Yan; Shen, Li; Zhang, Bin; Nestler, Eric J

    2016-06-01

    Depression is a complex, heterogeneous disorder and a leading contributor to the global burden of disease. Most previous research has focused on individual brain regions and genes contributing to depression. However, emerging evidence in humans and animal models suggests that dysregulated circuit function and gene expression across multiple brain regions drive depressive phenotypes. Here, we performed RNA sequencing on four brain regions from control animals and those susceptible or resilient to chronic social defeat stress at multiple time points. We employed an integrative network biology approach to identify transcriptional networks and key driver genes that regulate susceptibility to depressive-like symptoms. Further, we validated in vivo several key drivers and their associated transcriptional networks that regulate depression susceptibility and confirmed their functional significance at the levels of gene transcription, synaptic regulation, and behavior. Our study reveals novel transcriptional networks that control stress susceptibility and offers fundamentally new leads for antidepressant drug discovery. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Population genomic analyses based on 1 million SNPs in commercial egg layers.

    Directory of Open Access Journals (Sweden)

    Mahmood Gholami

    Full Text Available Identifying signatures of selection can provide valuable insight about the genes or genomic regions that are or have been under selective pressure, which can lead to a better understanding of genotype-phenotype relationships. A common strategy for selection signature detection is to compare samples from several populations and search for genomic regions with outstanding genetic differentiation. Wright's fixation index, FST, is a useful index for evaluation of genetic differentiation between populations. The aim of this study was to detect selective signatures between different chicken groups based on SNP-wise FST calculation. A total of 96 individuals of three commercial layer breeds and 14 non-commercial fancy breeds were genotyped with three different 600K SNP-chips. After filtering a total of 1 million SNPs were available for FST calculation. Averages of FST values were calculated for overlapping windows. Comparisons of these were then conducted between commercial egg layers and non-commercial fancy breeds, as well as between white egg layers and brown egg layers. Comparing non-commercial and commercial breeds resulted in the detection of 630 selective signatures, while 656 selective signatures were detected in the comparison between the commercial egg-layer breeds. Annotation of selection signature regions revealed various genes corresponding to productions traits, for which layer breeds were selected. Among them were NCOA1, SREBF2 and RALGAPA1 associated with reproductive traits, broodiness and egg production. Furthermore, several of the detected genes were associated with growth and carcass traits, including POMC, PRKAB2, SPP1, IGF2, CAPN1, TGFb2 and IGFBP2. Our approach demonstrates that including different populations with a specific breeding history can provide a unique opportunity for a better understanding of farm animal selection.

  11. Study on turbulent characteristics and transition behavior of combined-convection boundary layer

    International Nuclear Information System (INIS)

    Hattori, Yasuo

    2001-01-01

    The stabilizing mechanism of the turbulent combined-convection boundary layer along an isothermally-heated flat plate in air aided by a weak freestream are investigated experimentally and theoretically. The turbulent statistics of the combined-convection boundary layer measured with hot- and cold wires at different Grashof numbers indicates that with an increase in the freestream velocity, a similar change in the turbulent quantities appears independently of local Grashof number. Then based on the such experimental results, it is verified that the laminarization of the boundary layer due to an increase in freestream velocity arises at Grx / Rex 6 . Then, through the experiments with a particle image velocimetry (PIV), the spatio-temporal structure of the turbulent combined-convection boundary layer is investigated. For instantaneous velocity vectors obtained with PIV, large-scale fluid motions, which play a predominant role in the generation of turbulence, are frequently observed in the outer layer, while quasi-coherent structures do not exist in the near-wall region. Thus, it is revealed that increasing freestream restricts large-scale fluid motions in the outer layer, and consequently the generation of turbulence is suppressed and the boundary layer becomes laminar. (author)

  12. Large-area, laterally-grown epitaxial semiconductor layers

    Science.gov (United States)

    Han, Jung; Song, Jie; Chen, Danti

    2017-07-18

    Structures and methods for confined lateral-guided growth of a large-area semiconductor layer on an insulating layer are described. The semiconductor layer may be formed by heteroepitaxial growth from a selective growth area in a vertically-confined, lateral-growth guiding structure. Lateral-growth guiding structures may be formed in arrays over a region of a substrate, so as to cover a majority of the substrate region with laterally-grown epitaxial semiconductor tiles. Quality regions of low-defect, stress-free GaN may be grown on silicon.

  13. Recombination region improvement for reduced efficiency roll-off in phosphorescent OLEDs with dual emissive layers

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Zhu; Zhou, Shunliang [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Hu, Song [Chengdu Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209 (China); Yu, Junsheng, E-mail: jsyu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)

    2014-10-15

    High-performance phosphorescent organic light-emitting diodes (PhOLEDs) by using dual-emissive-layer (DEL) structure to reduce efficiency roll-off were fabricated. The DEL was comprised of a hole-transport-type host of N, N′-bis(naphthalen-1-yl)-N, N′-bis(phenyl)-benzidine (NPB) and a bipolar host of 4,4′-bis(carbazol-9-yl)biphenyl (CBP), which were both doped with an orange phosphorescent dopant of bis[2-(4-tert-butylphenyl)-benzothiazolato-N,C2′]iridium (acetylacetonate) [(t-bt){sub 2}Ir(acac)]. After the optimization of doping concentration of the first emissive layer (FEL), the device with DEL exhibited 11% lower roll-off power efficiency than single emissive layer devices (SED) when the luminance increased from 1000 cd/m{sup 2} to 10,000 cd/m{sup 2}. The hole–electron recombination zone in DEL was illuminated by inserting an ultrathin fluorescent probe of 4-(dicyanomethylene)-2-tert-butyl-6 (1,1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran (DCJTB) in different emissive regions. The performance improvement was attributed to the optimization of energy barrier and the expansion of exciton formation zone within the DEL. - Highlights: • PhOLEDs by using a dual-emissive-layer structure to reduce efficiency roll-off were fabricated. • The DED exhibited 11% lower efficiency roll-off, 57% lower turn-on voltage, and 174% higher brightness than SED. • A DCJTB fluorescent probe was inserted at different positions of DED to investigate the expansion of exciton formation zone.

  14. Distinct summer and winter bacterial communities in the active layer of Svalbard permafrost revealed by DNA- and RNA-based analyses

    DEFF Research Database (Denmark)

    Schostag, Morten; Stibal, Marek; Jacobsen, Carsten S.

    2015-01-01

    organic matter on the bacterial communities. The copy number of 16S rRNA genes and transcripts revealed no distinct seasonal changes indicating potential bacterial activity during winter despite soil temperatures well below -10ºC. Multivariate statistical analysis of the bacterial diversity data (DNA......The active layer of soil overlaying permafrost in the Arctic is subjected to dramatic annual changes in temperature and soil chemistry, which likely affect bacterial activity and community structure. We studied seasonal variations in the bacterial community of active layer soil from Svalbard (78º......N) by co-extracting DNA and RNA from 12 soil cores collected monthly over a year. PCR amplicons of 16S rRNA genes (DNA) and reverse transcribed transcripts (cDNA) were quantified and sequenced to test for the effect of low winter temperature and seasonal variation in concentration of easily degradable...

  15. Four-parametric two-layer algebraic model of transition boundary layer at a planar plate

    International Nuclear Information System (INIS)

    Labusov, A.N.; Lapin, Yu.V.

    1996-01-01

    Consideration is given to four-parametric two-layer algebraic model of transition boundary layer on a plane plate, based on generalization of one-parametric algebraic Prandtl-Loitsjansky-Klauzer-3 model. The algebraic model uses Prandtl formulas for mixing path with Loitsjansky damping multiplier in the internal region and the relation for turbulent viscosity, based on universal scales of external region and named the Klauzer-3 formula. 12 refs., 10 figs

  16. Formation mechanism of Al-depleted bands in MOVPE-AlGaN layer on GaN template with trenches

    Energy Technology Data Exchange (ETDEWEB)

    Kuwano, Noriyuki [Art, Science and Technology Center for Cooperative Research, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); Department of Applied Science for Electronics and Materials, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); Ezaki, Tetsuya; Kurogi, Takuya [Department of Applied Science for Electronics and Materials, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); Miyake, Hideto; Hiramatsu, Kazumasa [Department of Electrical and Electronic Engineering, Mie University, Tsu, Mie 514-8507 (Japan)

    2010-07-15

    A microstructure in an AlGaN/GaN layer was analyzed in detail by means of transmission electron microscopy (TEM) and scanning electron microscopy (SEM) with special attention to the formation of steps on the surface. The AlGaN layer was grown by MOVPE on a GaN template with periodic trenches. It was revealed that there formed were Al-depleted bands in the AlGaN layer. These bands were generated from rather lower regions in the AlGaN layer or those above the trenches, and run upwards. Some of them reached the top surface to connect a macro step. The formation mechanism of the Al-depleted region is discussed in terms of thermodynamics. If the total bonding energy of atoms on the macro step of surface is assumed to be smaller than that of atoms on a flat surface, the Al-depletion can be explained provided that the local equilibrium in concentration is conserved during the growth of AlGaN layer. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. The generation of post noon F3 layers over the dip equatorial location of Thiruvananthapuram- A new perspective

    Science.gov (United States)

    Mridula, N.; Pant, Tarun Kumar

    2018-05-01

    In the present paper, occurrence of post noon F3 layers over Thiruvananthapuram (8.5°N; 77°E; dip latitude ∼ 1.5 °N), a dip equatorial station in India have been investigated. F3 layers that occur beyond 13 IST and as observed using ground based ionosonde, for the years 2004-2008 have been studied. Our analysis shows that post noon F3 layers occur mostly on CEJ days around 16 IST to 18 IST. It is found that the time of the ionospheric E-region electric field reversal as inferred from collocated ground based magnetometer observations plays a crucial role in the generation of post noon F3 layers. In fact an early reversal of electric field emerged to be the necessary condition for the formation of post noon F3 layers. A time delay of three to 4 h is observed between the electric field reversal and the formation of F3 layer. It is proposed that this early reversal causes enhanced ionization over dip equatorial region, providing an additional ion drag to the flow of thermospheric zonal wind. This leads to accumulation of more ionization and neutrals culminating in the generation of post noon F3 layers as in the case of pre noon F3 layers. These results reveal that the generation of post noon F3 layers over the dip equatorial region is a natural consequence of the variability associated with the spatio-temporal evolution of EIA and prevailing thermospheric and ionospheric dynamics, and adds a new perspective to the present understanding.

  18. Observation of turnover of spontaneous polarization in ferroelectric layer of pentacene/poly-(vinylidene-trifluoroethylene) double-layer capacitor under photo illumination by optical second-harmonic generation measurement

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Zhemin [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Technology, Tsinghua University, Beijing 100084 (China); Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan); Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa, E-mail: iwamoto@pe.titech.ac.jp [Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan)

    2016-04-28

    The details of turnover process of spontaneous polarization and associated carrier motions in indium-tin oxide/poly-(vinylidene-trifluoroethylene)/pentacene/Au capacitor were analyzed by coupling displacement current measurement (DCM) and electric-field-induced optical second-harmonic generation (EFISHG) measurement. A model was set up from DCM results to depict the relationship between electric field in semiconductor layer and applied external voltage, proving that photo illumination effect on the spontaneous polarization process lied in variation of semiconductor conductivity. The EFISHG measurement directly and selectively probed the electric field distribution in semiconductor layer, modifying the model and revealing detailed carrier behaviors involving photo illumination effect, dipole reversal, and interfacial charging in the device. A further decrease of DCM current in the low voltage region under illumination was found as the result of illumination effect, and the result was argued based on the changing of the total capacitance of the double-layer capacitors.

  19. Observation of turnover of spontaneous polarization in ferroelectric layer of pentacene/poly-(vinylidene-trifluoroethylene) double-layer capacitor under photo illumination by optical second-harmonic generation measurement

    Science.gov (United States)

    Shi, Zhemin; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

    2016-04-01

    The details of turnover process of spontaneous polarization and associated carrier motions in indium-tin oxide/poly-(vinylidene-trifluoroethylene)/pentacene/Au capacitor were analyzed by coupling displacement current measurement (DCM) and electric-field-induced optical second-harmonic generation (EFISHG) measurement. A model was set up from DCM results to depict the relationship between electric field in semiconductor layer and applied external voltage, proving that photo illumination effect on the spontaneous polarization process lied in variation of semiconductor conductivity. The EFISHG measurement directly and selectively probed the electric field distribution in semiconductor layer, modifying the model and revealing detailed carrier behaviors involving photo illumination effect, dipole reversal, and interfacial charging in the device. A further decrease of DCM current in the low voltage region under illumination was found as the result of illumination effect, and the result was argued based on the changing of the total capacitance of the double-layer capacitors.

  20. Transmission electron microscopy characterization of Zircaloy-4 and ZIRLO™ oxide layers

    International Nuclear Information System (INIS)

    Gabory, Benoit de; Motta, Arthur T.; Wang, Ke

    2015-01-01

    Waterside corrosion of zirconium alloy nuclear fuel cladding varies markedly from one alloy to another. In addition, for a given alloy, the corrosion rate evolves during the corrosion process, most notably when the oxide loses its stability at the oxide transition. In an effort to understand the mechanism resulting in the variations of corrosion rate observed at the oxide transition, oxide layers formed on Zircaloy-4 and ZIRLO™ in high temperature water autoclave environments, and archived before and after the transition, are characterized using transmission electron microscopy. The study characterizes and compares the oxide morphology in both alloys at different times during the corrosion process, in an effort to understand the oxide growth mechanism for these alloys. Results show that the oxide is mainly composed of monoclinic ZrO 2 , with a preponderance of columnar oxide grains which extend to the oxide/metal interface. The oxide formed right after the transition has occurred, exhibits a 150 nm-wide layer of small equiaxed grains with high tetragonal oxide fraction. This layer has a similar morphology and structure as the first oxide layer formed (observed near the oxide/water interface). A study of the oxygen-rich region near the oxide/metal interface reveals a complex structure of different phases at different stages of corrosion. The interface exhibits an intermediate layer, identified as ZrO, a discontinuous layer of “blocky” Zr 3 O grains embedded in the ZrO layer, and a suboxide layer corresponding to an oxygen saturated solid solution in the metal matrix side. The thickness of this interfacial layer decreased markedly at the transition. Hydrides are also observed in that region, with a definite orientation relationship with the matrix. The observations of the oxide/metal interface are qualitatively similar for the two alloys but quantitatively different. The incorporation of intermetallic precipitates into the oxide layer is also studied, and

  1. Ocean barrier layers' effect on tropical cyclone intensification.

    Science.gov (United States)

    Balaguru, Karthik; Chang, Ping; Saravanan, R; Leung, L Ruby; Xu, Zhao; Li, Mingkui; Hsieh, Jen-Shan

    2012-09-04

    Improving a tropical cyclone's forecast and mitigating its destructive potential requires knowledge of various environmental factors that influence the cyclone's path and intensity. Herein, using a combination of observations and model simulations, we systematically demonstrate that tropical cyclone intensification is significantly affected by salinity-induced barrier layers, which are "quasi-permanent" features in the upper tropical oceans. When tropical cyclones pass over regions with barrier layers, the increased stratification and stability within the layer reduce storm-induced vertical mixing and sea surface temperature cooling. This causes an increase in enthalpy flux from the ocean to the atmosphere and, consequently, an intensification of tropical cyclones. On average, the tropical cyclone intensification rate is nearly 50% higher over regions with barrier layers, compared to regions without. Our finding, which underscores the importance of observing not only the upper-ocean thermal structure but also the salinity structure in deep tropical barrier layer regions, may be a key to more skillful predictions of tropical cyclone intensities through improved ocean state estimates and simulations of barrier layer processes. As the hydrological cycle responds to global warming, any associated changes in the barrier layer distribution must be considered in projecting future tropical cyclone activity.

  2. Thermal properties of redeposition layers in the JT-60U divertor region

    International Nuclear Information System (INIS)

    Ishimoto, Y.; Gotoh, Y.; Arai, T.; Masaki, K.; Miya, N.; Oyama, N.; Asakura, N.

    2006-01-01

    Thermal properties of the redeposition layer on the inner plate of the W-shaped divertor of JT-60U have been measured with laser flash method so as to estimate transient heat loads onto the divertor. Morphology analysis of the redeposition layer was conducted with a scanning electron microscope. Measurement of a redeposition layer sample of more than 200 μm thick, which had been produced near the most frequent striking point, showed following results: (1) the bulk density of the redeposition layer is about half of that of carbon fiber composite material; (2) the specific heat of the layer is roughly equal to that of the isotropic graphite; (3) the thermal conductivity of the redeposition layer is two orders of magnitude smaller than that of the carbon fiber composite. This low thermal conductivity of the redeposition layer is considered to be caused by a low graphitization degree of the redeposition layer. The difference between the divertor heat loads and the loss of the plasma stored energy becomes smaller taking account of thermal properties of the redeposition layer on the inner divertor, whereas estimated heat loads due to the ELMs is still larger than the loss. This is probably caused by the poloidal distribution of the thermal properties

  3. Three-layer magnetoconvection

    International Nuclear Information System (INIS)

    Lin, M.-K.; Silvers, L.J.; Proctor, M.R.E.

    2008-01-01

    It is believed that some stars have two or more convection zones in close proximity near to the stellar photosphere. These zones are separated by convectively stable regions that are relatively narrow. Due to the close proximity of these regions it is important to construct mathematical models to understand the transport and mixing of passive and dynamic quantities. One key quantity of interest is a magnetic field, a dynamic vector quantity, that can drastically alter the convectively driven flows, and have an important role in coupling the different layers. In this Letter we present the first investigation into the effect of an imposed magnetic field in such a geometry. We focus our attention on the effect of field strength and show that, while there are some similarities with results for magnetic field evolution in a single layer, new and interesting phenomena are also present in a three layer system

  4. Mucosal Immunogenicity of Genetically Modified Lactobacillus acidophilus Expressing an HIV-1 Epitope within the Surface Layer Protein.

    Directory of Open Access Journals (Sweden)

    Akinobu Kajikawa

    Full Text Available Surface layer proteins of probiotic lactobacilli are theoretically efficient epitope-displaying scaffolds for oral vaccine delivery due to their high expression levels and surface localization. In this study, we constructed genetically modified Lactobacillus acidophilus strains expressing the membrane proximal external region (MPER from human immunodeficiency virus type 1 (HIV-1 within the context of the major S-layer protein, SlpA. Intragastric immunization of mice with the recombinants induced MPER-specific and S-layer protein-specific antibodies in serum and mucosal secretions. Moreover, analysis of systemic SlpA-specific cytokines revealed that the responses appeared to be Th1 and Th17 dominant. These findings demonstrated the potential use of the Lactobacillus S-layer protein for development of oral vaccines targeting specific peptides.

  5. PARALLEL EVOLUTION OF QUASI-SEPARATRIX LAYERS AND ACTIVE REGION UPFLOWS

    Energy Technology Data Exchange (ETDEWEB)

    Mandrini, C. H.; Cristiani, G. D.; Nuevo, F. A.; Vásquez, A. M. [Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, CC. 67, Suc. 28 Buenos Aires, 1428 (Argentina); Baker, D.; Driel-Gesztelyi, L. van [UCL-Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey, RH5 6NT (United Kingdom); Démoulin, P.; Pick, M. [Observatoire de Paris, LESIA, UMR 8109 (CNRS), F-92195 Meudon Principal Cedex (France); Vargas Domínguez, S. [Observatorio Astronómico Nacional, Universidad Nacional de Colombia, Bogotá (Colombia)

    2015-08-10

    Persistent plasma upflows were observed with Hinode’s EUV Imaging Spectrometer (EIS) at the edges of active region (AR) 10978 as it crossed the solar disk. We analyze the evolution of the photospheric magnetic and velocity fields of the AR, model its coronal magnetic field, and compute the location of magnetic null-points and quasi-sepratrix layers (QSLs) searching for the origin of EIS upflows. Magnetic reconnection at the computed null points cannot explain all of the observed EIS upflow regions. However, EIS upflows and QSLs are found to evolve in parallel, both temporarily and spatially. Sections of two sets of QSLs, called outer and inner, are found associated to EIS upflow streams having different characteristics. The reconnection process in the outer QSLs is forced by a large-scale photospheric flow pattern, which is present in the AR for several days. We propose a scenario in which upflows are observed, provided that a large enough asymmetry in plasma pressure exists between the pre-reconnection loops and lasts as long as a photospheric forcing is at work. A similar mechanism operates in the inner QSLs; in this case, it is forced by the emergence and evolution of the bipoles between the two main AR polarities. Our findings provide strong support for the results from previous individual case studies investigating the role of magnetic reconnection at QSLs as the origin of the upflowing plasma. Furthermore, we propose that persistent reconnection along QSLs does not only drive the EIS upflows, but is also responsible for the continuous metric radio noise-storm observed in AR 10978 along its disk transit by the Nançay Radio Heliograph.

  6. Mapping the layer count of few-layer hexagonal boron nitride at high lateral spatial resolutions

    Science.gov (United States)

    Mohsin, Ali; Cross, Nicholas G.; Liu, Lei; Watanabe, Kenji; Taniguchi, Takashi; Duscher, Gerd; Gu, Gong

    2018-01-01

    Layer count control and uniformity of two dimensional (2D) layered materials are critical to the investigation of their properties and to their electronic device applications, but methods to map 2D material layer count at nanometer-level lateral spatial resolutions have been lacking. Here, we demonstrate a method based on two complementary techniques widely available in transmission electron microscopes (TEMs) to map the layer count of multilayer hexagonal boron nitride (h-BN) films. The mass-thickness contrast in high-angle annular dark-field (HAADF) imaging in the scanning transmission electron microscope (STEM) mode allows for thickness determination in atomically clean regions with high spatial resolution (sub-nanometer), but is limited by surface contamination. To complement, another technique based on the boron K ionization edge in the electron energy loss spectroscopy spectrum (EELS) of h-BN is developed to quantify the layer count so that surface contamination does not cause an overestimate, albeit at a lower spatial resolution (nanometers). The two techniques agree remarkably well in atomically clean regions with discrepancies within  ±1 layer. For the first time, the layer count uniformity on the scale of nanometers is quantified for a 2D material. The methodology is applicable to layer count mapping of other 2D layered materials, paving the way toward the synthesis of multilayer 2D materials with homogeneous layer count.

  7. Symbolic joint entropy reveals the coupling of various brain regions

    Science.gov (United States)

    Ma, Xiaofei; Huang, Xiaolin; Du, Sidan; Liu, Hongxing; Ning, Xinbao

    2018-01-01

    The convergence and divergence of oscillatory behavior of different brain regions are very important for the procedure of information processing. Measurements of coupling or correlation are very useful to study the difference of brain activities. In this study, EEG signals were collected from ten subjects under two conditions, i.e. eyes closed state and idle with eyes open. We propose a nonlinear algorithm, symbolic joint entropy, to compare the coupling strength among the frontal, temporal, parietal and occipital lobes and between two different states. Instead of decomposing the EEG into different frequency bands (theta, alpha, beta, gamma etc.), the novel algorithm is to investigate the coupling from the entire spectrum of brain wave activities above 4Hz. The coupling coefficients in two states with different time delay steps are compared and the group statistics are presented as well. We find that the coupling coefficient of eyes open state with delay consistently lower than that of eyes close state across the group except for one subject, whereas the results without delay are not consistent. The differences between two brain states with non-zero delay can reveal the intrinsic inter-region coupling better. We also use the well-known Hénon map data to validate the algorithm proposed in this paper. The result shows that the method is robust and has a great potential for other physiologic time series.

  8. Thermal Analysis of Low Layer Density Multilayer Insulation Test Results

    Science.gov (United States)

    Johnson, Wesley L.

    2011-01-01

    Investigation of the thermal performance of low layer density multilayer insulations is important for designing long-duration space exploration missions involving the storage of cryogenic propellants. Theoretical calculations show an analytical optimal layer density, as widely reported in the literature. However, the appropriate test data by which to evaluate these calculations have been only recently obtained. As part of a recent research project, NASA procured several multilayer insulation test coupons for calorimeter testing. These coupons were configured to allow for the layer density to be varied from 0.5 to 2.6 layer/mm. The coupon testing was completed using the cylindrical Cryostat-l00 apparatus by the Cryogenics Test Laboratory at Kennedy Space Center. The results show the properties of the insulation as a function of layer density for multiple points. Overlaying these new results with data from the literature reveals a minimum layer density; however, the value is higher than predicted. Additionally, the data show that the transition region between high vacuum and no vacuum is dependent on the spacing of the reflective layers. Historically this spacing has not been taken into account as thermal performance was calculated as a function of pressure and temperature only; however the recent testing shows that the data is dependent on the Knudsen number which takes into account pressure, temperature, and layer spacing. These results aid in the understanding of the performance parameters of MLI and help to complete the body of literature on the topic.

  9. Article with buffer layer and method of making the same

    Science.gov (United States)

    McCamy, James W.; Ma, Zhixun; Kabagambe, Benjamin; Koram, Kwaku K.; Hung, Cheng-Hung; Nelis, Gary J.

    2017-11-14

    A method of forming a coating layer on a glass substrate in a glass manufacturing process includes: providing a first coating precursor material for a selected coating layer composition to at least one multislot coater to form a first coating region of the selected coating layer; and providing a second coating precursor material for the selected coating layer composition to the multislot coater to form a second coating region of the selected coating layer over the first region. The first coating precursor material is different than the second precursor coating material.

  10. Wake Instabilities Behind Discrete Roughness Elements in High Speed Boundary Layers

    Science.gov (United States)

    Choudhari, Meelan; Li, Fei; Chang, Chau-Lyan; Norris, Andrew; Edwards, Jack

    2013-01-01

    Computations are performed to study the flow past an isolated, spanwise symmetric roughness element in zero pressure gradient boundary layers at Mach 3.5 and 5.9, with an emphasis on roughness heights of less than 55 percent of the local boundary layer thickness. The Mach 5.9 cases include flow conditions that are relevant to both ground facility experiments and high altitude flight ("cold wall" case). Regardless of the Mach number, the mean flow distortion due to the roughness element is characterized by long-lived streamwise streaks in the roughness wake, which can support instability modes that did not exist in the absence of the roughness element. The higher Mach number cases reveal a variety of instability mode shapes with velocity fluctuations concentrated in different localized regions of high base flow shear. The high shear regions vary from the top of a mushroom shaped structure characterizing the centerline streak to regions that are concentrated on the sides of the mushroom. Unlike the Mach 3.5 case with nearly same values of scaled roughness height k/delta and roughness height Reynolds number Re(sub kk), the odd wake modes in both Mach 5.9 cases are significantly more unstable than the even modes of instability. Additional computations for a Mach 3.5 boundary layer indicate that the presence of a roughness element can also enhance the amplification of first mode instabilities incident from upstream. Interactions between multiple roughness elements aligned along the flow direction are also explored.

  11. Genome Scan for Selection in Structured Layer Chicken Populations Exploiting Linkage Disequilibrium Information.

    Directory of Open Access Journals (Sweden)

    Mahmood Gholami

    Full Text Available An increasing interest is being placed in the detection of genes, or genomic regions, that have been targeted by selection because identifying signatures of selection can lead to a better understanding of genotype-phenotype relationships. A common strategy for the detection of selection signatures is to compare samples from distinct populations and to search for genomic regions with outstanding genetic differentiation. The aim of this study was to detect selective signatures in layer chicken populations using a recently proposed approach, hapFLK, which exploits linkage disequilibrium information while accounting appropriately for the hierarchical structure of populations. We performed the analysis on 70 individuals from three commercial layer breeds (White Leghorn, White Rock and Rhode Island Red, genotyped for approximately 1 million SNPs. We found a total of 41 and 107 regions with outstanding differentiation or similarity using hapFLK and its single SNP counterpart FLK respectively. Annotation of selection signature regions revealed various genes and QTL corresponding to productions traits, for which layer breeds were selected. A number of the detected genes were associated with growth and carcass traits, including IGF-1R, AGRP and STAT5B. We also annotated an interesting gene associated with the dark brown feather color mutational phenotype in chickens (SOX10. We compared FST, FLK and hapFLK and demonstrated that exploiting linkage disequilibrium information and accounting for hierarchical population structure decreased the false detection rate.

  12. Boundary Layer Depth In Coastal Regions

    Science.gov (United States)

    Porson, A.; Schayes, G.

    The results of earlier studies performed about sea breezes simulations have shown that this is a relevant feature of the Planetary Boundary Layer that still requires effort to be diagnosed properly by atmospheric models. Based on the observations made during the ESCOMPTE campaign, over the Mediterranean Sea, different CBL and SBL height estimation processes have been tested with a meso-scale model, TVM. The aim was to compare the critical points of the BL height determination computed using turbulent kinetic energy profile with some other standard evaluations. Moreover, these results have been analysed with different mixing length formulation. The sensitivity of formulation is also analysed with a simple coastal configuration.

  13. The national tree-list layer

    Science.gov (United States)

    Stacy A. Drury; Jason M. Herynk

    2011-01-01

    The National Tree-List Layer (NTLL) project used LANDFIRE map products to produce the first national tree-list map layer that represents tree populations at stand and regional levels. The NTLL was produced in a short time frame to address the needs of Fire and Aviation Management for a map layer that could be used as input for simulating fire-caused tree mortality...

  14. Similarity solution and Runge Kutta method to a thermal boundary layer model at the entrance region of a circular tube: The Lévêque Approximation

    Directory of Open Access Journals (Sweden)

    Ali Belhocine

    2018-01-01

    Full Text Available In the thermal entrance region, a thermal boundary layer develops and also reaches the circular tube center. The fully developed region is the zone in which the flow is both hydrodynamically and thermally developed. The heat flux will be higher near the inlet because the heat transfer coefficient is highest at the tube inlet where the thickness of the thermal boundary layer is zero and decreases gradually to the fully developed value. In this paper, the assumptions implicit in Leveque's approximation are re-examined, and the analytical solution of the problem with additional boundary conditions, for the temperature field and the boundary layer thickness through the long tube is presented. By defining a similarity variable, the governing equations are reduced to a dimensionless equation with an analytic solution in the entrance region. This report gives justification for the similarity variable via scaling analysis, details the process of converting to a similarity form, and presents a similarity solution. The analytical solutions are then checked against numerical solution programming by Fortran code obtained via using Runge-Kutta fourth order (RK4 method. Finally, others important thermal results obtained from this analysis, such as; approximate Nusselt number in the thermal entrance region was discussed in detail.

  15. Heavy Metals Technogenic Pollution of Plough Lands Arable Layer in the Chelyabinsk Region

    Science.gov (United States)

    Mantorova, G. F.

    2017-11-01

    Environmental protection and rational use of natural resources in agriculture are the main directions of this scientific research. Contamination is caused by the substances of chemical, radiation and biological origin above the maximum permissible concentration (MPC). The main source of soil contamination in the arable land, hayfields and pastures is the waste of livestock complexes, agricultural chemicals (fertilizers, pesticides), motor vehicle exhausts, industrial emissions, sewage from settlements, etc. The ecological state of the soil and vegetation cover is largely determined by agricultural activities. The agricultural production technology complicating is accompanied by increase in the degree of environmental risk, especially in the chemicalization of agriculture. Pollution also enters the soil with atmospheric precipitation, surface waste. They are also introduced into the soil layer by soil and groundwater. The most dangerous for human health is considered to be contamination with heavy metals (HM)-lead, mercury and cadmium. However, the concentration of the rest elements is no less harmful. The paradox of heavy metals is that in certain quantities they are necessary to ensure the normal life of plants and organisms but their excess can lead to serious diseases and even death. A nutritional cycle causes harmful compounds to enter the human body and often cause great harm to health. The present work reveals the results of the research of a long-term experience on accumulation and distribution of heavy metals on the arable layer profile depending on the concentration in humus soil and the system of ground processing.

  16. Layer-specific morphological and molecular differences in neocortical astrocytes and their dependence on neuronal layers.

    Science.gov (United States)

    Lanjakornsiripan, Darin; Pior, Baek-Jun; Kawaguchi, Daichi; Furutachi, Shohei; Tahara, Tomoaki; Katsuyama, Yu; Suzuki, Yutaka; Fukazawa, Yugo; Gotoh, Yukiko

    2018-04-24

    Non-pial neocortical astrocytes have historically been thought to comprise largely a nondiverse population of protoplasmic astrocytes. Here we show that astrocytes of the mouse somatosensory cortex manifest layer-specific morphological and molecular differences. Two- and three-dimensional observations revealed that astrocytes in the different layers possess distinct morphologies as reflected by differences in cell orientation, territorial volume, and arborization. The extent of ensheathment of synaptic clefts by astrocytes in layer II/III was greater than that by those in layer VI. Moreover, differences in gene expression were observed between upper-layer and deep-layer astrocytes. Importantly, layer-specific differences in astrocyte properties were abrogated in reeler and Dab1 conditional knockout mice, in which neuronal layers are disturbed, suggesting that neuronal layers are a prerequisite for the observed morphological and molecular differences of neocortical astrocytes. This study thus demonstrates the existence of layer-specific interactions between neurons and astrocytes, which may underlie their layer-specific functions.

  17. Local Helioseismology of Emerging Active Regions: A Case Study

    Science.gov (United States)

    Kosovichev, Alexander G.; Zhao, Junwei; Ilonidis, Stathis

    2018-04-01

    Local helioseismology provides a unique opportunity to investigate the subsurface structure and dynamics of active regions and their effect on the large-scale flows and global circulation of the Sun. We use measurements of plasma flows in the upper convection zone, provided by the Time-Distance Helioseismology Pipeline developed for analysis of solar oscillation data obtained by Helioseismic and Magnetic Imager (HMI) on Solar Dynamics Observatory (SDO), to investigate the subsurface dynamics of emerging active region NOAA 11726. The active region emergence was detected in deep layers of the convection zone about 12 hours before the first bipolar magnetic structure appeared on the surface, and 2 days before the emergence of most of the magnetic flux. The speed of emergence determined by tracking the flow divergence with depth is about 1.4 km/s, very close to the emergence speed in the deep layers. As the emerging magnetic flux becomes concentrated in sunspots local converging flows are observed beneath the forming sunspots. These flows are most prominent in the depth range 1-3 Mm, and remain converging after the formation process is completed. On the larger scale converging flows around active region appear as a diversion of the zonal shearing flows towards the active region, accompanied by formation of a large-scale vortex structure. This process occurs when a substantial amount of the magnetic flux emerged on the surface, and the converging flow pattern remains stable during the following evolution of the active region. The Carrington synoptic flow maps show that the large-scale subsurface inflows are typical for active regions. In the deeper layers (10-13 Mm) the flows become diverging, and surprisingly strong beneath some active regions. In addition, the synoptic maps reveal a complex evolving pattern of large-scale flows on the scale much larger than supergranulation

  18. Multi-region and single-cell sequencing reveal variable genomic heterogeneity in rectal cancer.

    Science.gov (United States)

    Liu, Mingshan; Liu, Yang; Di, Jiabo; Su, Zhe; Yang, Hong; Jiang, Beihai; Wang, Zaozao; Zhuang, Meng; Bai, Fan; Su, Xiangqian

    2017-11-23

    Colorectal cancer is a heterogeneous group of malignancies with complex molecular subtypes. While colon cancer has been widely investigated, studies on rectal cancer are very limited. Here, we performed multi-region whole-exome sequencing and single-cell whole-genome sequencing to examine the genomic intratumor heterogeneity (ITH) of rectal tumors. We sequenced nine tumor regions and 88 single cells from two rectal cancer patients with tumors of the same molecular classification and characterized their mutation profiles and somatic copy number alterations (SCNAs) at the multi-region and the single-cell levels. A variable extent of genomic heterogeneity was observed between the two patients, and the degree of ITH increased when analyzed on the single-cell level. We found that major SCNAs were early events in cancer development and inherited steadily. Single-cell sequencing revealed mutations and SCNAs which were hidden in bulk sequencing. In summary, we studied the ITH of rectal cancer at regional and single-cell resolution and demonstrated that variable heterogeneity existed in two patients. The mutational scenarios and SCNA profiles of two patients with treatment naïve from the same molecular subtype are quite different. Our results suggest each tumor possesses its own architecture, which may result in different diagnosis, prognosis, and drug responses. Remarkable ITH exists in the two patients we have studied, providing a preliminary impression of ITH in rectal cancer.

  19. Nanopore Measurements of Filamentous Viruses Reveal a Sub-nanometer-Scale Stagnant Fluid Layer.

    Science.gov (United States)

    McMullen, Angus J; Tang, Jay X; Stein, Derek

    2017-11-28

    We report measurements and analyses of nanopore translocations by fd and M13, two related strains of filamentous virus that are identical except for their charge densities. The standard continuum theory of electrokinetics greatly overestimates the translocation speed and the conductance associated with counterions for both viruses. Furthermore, fd and M13 behave differently from one another, even translocating in opposite directions under certain conditions. This cannot be explained by Manning-condensed counterions or a number of other proposed models. Instead, we argue that these anomalous findings are consequences of the breakdown of the validity of continuum hydrodynamics at the scale of a few molecular layers. Next to a polyelectrolyte, there exists an extra-viscous, sub-nanometer-thin boundary layer that has a giant influence on the transport characteristics. We show that a stagnant boundary layer captures the essential hydrodynamics and extends the validity of the electrokinetic theory beyond the continuum limit. A stagnant layer with a thickness of about half a nanometer consistently improves predictions of the ionic current change induced by virus translocations and of the translocation velocity for both fd and M13 over a wide range of nanopore dimensions and salt concentrations.

  20. Regional two-dimensional magnetotelluric profile in West Bohemia/Vogtland reveals deep conductive channel into the earthquake swarm region

    Science.gov (United States)

    Muñoz, Gerard; Weckmann, Ute; Pek, Josef; Kováčiková, Světlana; Klanica, Radek

    2018-03-01

    The West Bohemia/Vogtland region, characterized by the intersection of the Eger (Ohře) Rift and the Mariánské Lázně fault, is a geodynamically active area exhibiting repeated occurrence of earthquake swarms, massive CO2 emanations and mid Pleistocene volcanism. The Eger Rift is the only known intra-continental region in Europe where such deep seated, active lithospheric processes currently take place. We present an image of electrical resistivity obtained from two-dimensional inversion of magnetotelluric (MT) data acquired along a regional profile crossing the Eger Rift. At the near surface, the Cheb basin and the aquifer feeding the mofette fields of Bublák and Hartoušov have been imaged as part of a region of very low resistivity. The most striking resistivity feature, however, is a deep reaching conductive channel which extends from the surface into the lower crust spatially correlated with the hypocentres of the seismic events of the Nový Kostel Focal Zone. This channel has been interpreted as imaging a pathway from a possible mid-crustal fluid reservoir to the surface. The resistivity model reinforces the relation between the fluid circulation along deep-reaching faults and the generation of the earthquakes. Additionally, a further conductive channel has been revealed to the south of the profile. This other feature could be associated to fossil hydrothermal alteration related to Mýtina and/or Neualbenreuth Maar structures or alternatively could be the signature of a structure associated to the suture between the Saxo-Thuringian and Teplá-Barrandian zones, whose surface expression is located only a few kilometres away.

  1. Superfluid Boundary Layer.

    Science.gov (United States)

    Stagg, G W; Parker, N G; Barenghi, C F

    2017-03-31

    We model the superfluid flow of liquid helium over the rough surface of a wire (used to experimentally generate turbulence) profiled by atomic force microscopy. Numerical simulations of the Gross-Pitaevskii equation reveal that the sharpest features in the surface induce vortex nucleation both intrinsically (due to the raised local fluid velocity) and extrinsically (providing pinning sites to vortex lines aligned with the flow). Vortex interactions and reconnections contribute to form a dense turbulent layer of vortices with a nonclassical average velocity profile which continually sheds small vortex rings into the bulk. We characterize this layer for various imposed flows. As boundary layers conventionally arise from viscous forces, this result opens up new insight into the nature of superflows.

  2. Wave like signatures in aerosol optical depth and associated radiative impacts over the central Himalayan region

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, K. K.; Phanikumar, D. V.; Kumar, K.  Niranjan; Reddy, Kishore; Kotamarthi, V. R.; Newsom, Rob K.; Ouarda, Taha B. M. J.

    2015-10-01

    In this study, we present a case study on 16 October 2011 to show the first observational evidence of the influence of short period gravity waves in aerosol transport during daytime over the central Himalayan region. The Doppler lidar data has been utilized to address the daytime boundary layer evolution and related aerosol dynamics over the site. Mixing layer height is estimated by wavelet covariance transform method and found to be ~ 0.7 km, AGL. Aerosol optical depth observations during daytime revealed an asymmetry showing clear enhancement during afternoon hours as compared to forenoon. Interestingly, Fourier and wavelet analysis of vertical velocity and attenuated backscatter showed similar 50-90 min short period gravity wave signatures during afternoon hours. Moreover, our observations showed that gravity waves are dominant within the boundary layer implying that the daytime boundary layer dynamics is playing a vital role in transporting the aerosols from surface to the top of the boundary layer. Similar modulations are also evident in surface parameters like temperature, relative humidity and wind speed indicating these waves are associated with the dynamical aspects over Himalayan region. Finally, time evolution of range-23 height indicator snapshots during daytime showed strong upward velocities especially during afternoon hours implying that convective processes through short period gravity waves plays a significant role in transporting aerosols from the nearby valley region to boundary layer top over the site. These observations also establish the importance of wave induced daytime convective boundary layer dynamics in the lower Himalayan region.

  3. Passive scalar transport in peripheral regions of random flows

    International Nuclear Information System (INIS)

    Chernykh, A.; Lebedev, V.

    2011-01-01

    We investigate statistical properties of the passive scalar mixing in random (turbulent) flows assuming its diffusion to be weak. Then at advanced stages of the passive scalar decay, its unmixed residue is primarily concentrated in a narrow diffusive layer near the wall and its transport to the bulk goes through the peripheral region (laminar sublayer of the flow). We conducted Lagrangian numerical simulations of the process for different space dimensions d and revealed structures responsible for the transport, which are passive scalar tongues pulled from the diffusive boundary layer to the bulk. We investigated statistical properties of the passive scalar and of the passive scalar integrated along the wall. Moments of both objects demonstrate scaling behavior outside the diffusive boundary layer. We propose an analytic scheme for the passive scalar statistics, explaining the features observed numerically.

  4. Characteristics of the magnetospheric boundary layer and magnetopause layer as observed by Imp 6

    International Nuclear Information System (INIS)

    Eastman, T.E.; Hones, E.W. Jr.

    1979-01-01

    Imp 6 observations of the low-latitude magnetospheric boundary layer indicate that the plasma within it is supplied primarily by direct entry of magnetosheath plasma across the magnetopause layer. We define the magnetopause layer as the current layer (separating the magnetosheath from the boundary layer) through which the magnetic field shifts in direction. High temporal resolution (3-s average) data reveal that in a majority of Imp 6 magnetopause crossing, no distinct changes in electron density or energry spectra are observed at the magne opause layer. In all Imp 6 crossings, some magnetosheathlike plasma is observed earthward of the magnetopause layer, implying the existence of a boundary layer. Boundary layer electron energy spectra are often virtually indistinguishable from the adjacent magnetosheath spectra. Low-latitude boundary layer bulk plasma flow as observed by Imp 6 almost always has an antisunward component and often has a significant cross-field component. The boundary layer thickness is highly variable and is generally much larger than the magnetopause layer thickness. Energetic electron pitch angle distributions indicate that the low-latitude boundary layers is normally on closed field lines. We conclude that diffusive as well as nondiffusive processes probably contribute to the entry of magnetosheath plasma into the boundary layer

  5. Development of examination technique for oxide layer thickness measurement of irradiated fuel rods

    International Nuclear Information System (INIS)

    Koo, D. S.; Park, S. W.; Kim, J. H.; Seo, H. S.; Min, D. K.; Kim, E. K.; Chun, Y. B.; Bang, K. S.

    1999-06-01

    Technique for oxide layer thickness measurement of irradiated fuel rods was developed to measure oxide layer thickness and study characteristic of fuel rods. Oxide layer thickness of irradiated fuels were measured, analyzed. Outer oxide layer thickness of 3 cycle-irradiated fuel rods were 20 - 30 μm, inner oxide layer thickness 0 - 10 μm and inner oxide layer thickness on cracked cladding about 30 μm. Oxide layer thickness of 4 cycle-irradiated fuel rods were about 2 times as thick as those of 1 cycle-irradiated fuel rods. Oxide layer on lower region of irradiated fuel rods was thin and oxide layer from lower region to upper region indicated gradual increase in thickness. Oxide layer thickness from 2500 to 3000 mm showed maximum and oxide layer thickness from 3000 to top region of irradiated fuel rods showed decreasing trend. Inner oxide layer thicknesses of 4 cycle-irradiated fuel rod were about 8 μm at 750 - 3500 mm from the bottom end of fuel rod. Outer oxide layer thickness were about 8 μm at 750 - 1000 mm from the bottom end of fuel rod. These indicated gradual increase up to upper region from the bottom end of fuel rod. These indicated gradual increase up to upper region from the bottom end of fuel. Oxide layer thickness technique will apply safety evaluation and study of reactor fuels. (author). 6 refs., 14 figs

  6. Structural and electrical properties of epitaxial Si layers prepared by E-beam evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Dogan, P. [Hahn-Meitner-Institut Berlin, Kekulestr. 5, 12489 Berlin (Germany)], E-mail: pinar.dogan@hmi.de; Rudigier, E.; Fenske, F.; Lee, K.Y.; Gorka, B.; Rau, B.; Conrad, E.; Gall, S. [Hahn-Meitner-Institut Berlin, Kekulestr. 5, 12489 Berlin (Germany)

    2008-08-30

    In this work, we present structural and electrical properties of thin Si films which are homoepitaxially grown at low substrate temperatures (T{sub s} 450-700 deg. C) by high-rate electron beam evaporation. As substrates, monocrystalline Si wafers with (100) and (111) orientations and polycrystalline Si (poly-Si) seed layers on glass were used. Applying Secco etching, films grown on Si(111) wafers exhibit a decreasing etch pit density with increasing T{sub s}. The best structural quality of the films was obtained on Si(100) wafers. Defect etching on epitaxially grown poly-Si absorbers reveal regions with different crystalline quality. Solar cells have been prepared on both wafers and seed layers. Applying Rapid Thermal Annealing (RTA) and Hydrogen plasma passivation an open circuit voltage of 570 mV for wafer based and 346 mV for seed layer based solar cells have been reached.

  7. Catalytic, Conductive Bipolar Membrane Interfaces through Layer-by-Layer Deposition for the Design of Membrane-Integrated Artificial Photosynthesis Systems.

    Science.gov (United States)

    McDonald, Michael B; Freund, Michael S; Hammond, Paula T

    2017-11-23

    In the presence of an electric field, bipolar membranes (BPMs) are capable of initiating water disassociation (WD) within the interfacial region, which can make water splitting for renewable energy in the presence of a pH gradient possible. In addition to WD catalytic efficiency, there is also the need for electronic conductivity in this region for membrane-integrated artificial photosynthesis (AP) systems. Graphene oxide (GO) was shown to catalyze WD and to be controllably reduced, which resulted in electronic conductivity. Layer-by-layer (LbL) film deposition was employed to improve GO film uniformity in the interfacial region to enhance WD catalysis and, through the addition of a conducting polymer in the process, add electronic conductivity in a hybrid film. Three different deposition methods were tested to optimize conducting polymer synthesis with the oxidant in a metastable solution and to yield the best film properties. It was found that an approach that included substrate dipping in a solution containing the expected final monomer/oxidant ratio provided the most predictable film growth and smoothest films (by UV/Vis spectroscopy and atomic force microscopy/scanning electron microscopy, respectively), whereas dipping in excess oxidant or co-spraying the oxidant and monomer produced heterogeneous films. Optimized films were found to be electronically conductive and produced a membrane ohmic drop that was acceptable for AP applications. Films were integrated into the interfacial region of BPMs and revealed superior WD efficiency (≥1.4 V at 10 mA cm -2 ) for thinner films (<10 bilayers≈100 nm) than for either the pure GO catalyst or conducting polymer individually, which indicated that there was a synergistic effect between these materials in the structure configured by the LbL method. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Design of a size-efficient tunable metamaterial absorber based on leaf-shaped cell at near-infrared regions

    Science.gov (United States)

    Huang, Hailong; Xia, Hui; Xie, Wenke; Guo, Zhibo; Li, Hongjian

    2018-06-01

    A size-efficient tunable metamaterial absorber (MA) composed of metallic leaf-shaped cell, graphene layer, silicon substrate, and bottom metal film is investigated theoretically and numerically at near-infrared (NIR) regions. Simulation results reveal that the single-band high absorption of 91.9% is obtained at 1268.7 nm. Further results show that the single-band can be simply changed into dual-band high absorption by varying the geometric parameters of top metallic layer at same wavelength regions, yielding two high absorption coefficients of 96.6% and 95.3% at the wavelengths of 1158.7 nm and 1323.6 nm, respectively. And the effect of related geometric parameter on dual-band absorption intensities is also investigated to obtain the optimized one. The peak wavelength can be tuned via modifying the Fermi energy of the graphene layer through controlling the external gate voltage. The work shows that the proposed strategy can be applied to other design of the dual-band structure at infrared regions.

  9. Analysis of wave-like oscillations in parameters of sporadic E layer and neutral atmosphere

    Science.gov (United States)

    Mošna, Z.; Koucká Knížová, P.

    2012-12-01

    The present study mainly concerns the wave-like activity in the ionospheric sporadic E layer (Es) and in the lower lying stratosphere. The proposed analysis involves parameters describing the state of plasma in the sporadic E layer. Critical frequencies foEs and layer heights hEs were measured at the Pruhonice station (50°N, 14.5°E) during summer campaigns 2004, 2006 and 2008. Further, we use neutral atmosphere (temperature data at 10 hPa) data from the same time interval. The analysis concentrates on vertically propagating wave-like structures within distant atmospheric regions. By means of continuous wavelet transform (CWT) we have detected significant wave-like oscillation at periods covering tidal and planetary oscillation domains both in the Es layer parameters (some of them were reported earlier, for instance in works of Abdu et al., 2003; Pancheva and Mitchel, 2004; Pancheva et al., 2003; Šauli and Bourdillon, 2008) and in stratospheric temperature variations. Further analyses using cross wavelet transform (XWT) and wavelet coherence analysis (WTC) show that despite high wave-like activity in a wide period range, there are only limited coherent wave-like bursts present in both spectra. Such common coherent wave bursts occur on periods close to eigen-periods of the terrestrial atmosphere. We suppose that vertical coupling between atmospheric regions realized by vertically propagating planetary waves occurs predominantly on periods close to those of Rossby modes. Analysis of the phase shift between data from distant atmospheric regions reveals high variability and very likely supports the non-linear scenario of the vertical coupling provided by planetary waves.

  10. Electric field measurements of DC and long wavelength structures associated with sporadic-E layers and QP radar echoes

    Directory of Open Access Journals (Sweden)

    S. Ohtsuki

    2005-10-01

    Full Text Available Electric field and plasma density data gathered on a sounding rocket launched from Uchinoura Space Center, Japan, reveal a complex electrodynamics associated with sporadic-E layers and simultaneous observations of quasi-periodic radar echoes. The electrodynamics are characterized by spatial and temporal variations that differed considerably between the rocket's upleg and downleg traversals of the lower ionosphere. Within the main sporadic-E layer (95–110 km on the upleg, the electric fields were variable, with amplitudes of 2–4 mV/m that changed considerably within altitude intervals of 1–3 km. The identification of polarization electric fields coinciding with plasma density enhancements and/or depletions is not readily apparent. Within this region on the downleg, however, the direction of the electric field revealed a marked change that coincided precisely with the peak of a single, narrow sporadic-E plasma density layer near 102.5 km. This shear was presumably associated with the neutral wind shear responsible for the layer formation. The electric field data above the sporadic-E layer on the upleg, from 110 km to the rocket apogee of 152 km, revealed a continuous train of distinct, large scale, quasi-periodic structures with wavelengths of 10–15 km and wavevectors oriented between the NE-SW quadrants. The electric field structures had typical amplitudes of 3–5 mV/m with one excursion to 9 mV/m, and in a very general sense, were associated with perturbations in the plasma density. The electric field waveforms showed evidence for steepening and/or convergence effects and presumably had mapped upwards along the magnetic field from the sporadic-E region below. Candidate mechanisms to explain the origin of these structures include the Kelvin-Helmholtz instability and the Es-layer instability. In both cases, the same shear that formed the sporadic-E layer would provide the energy to generate the km-scale structures. Other possibilities

  11. Air Layer Drag Reduction

    Science.gov (United States)

    Ceccio, Steven; Elbing, Brian; Winkel, Eric; Dowling, David; Perlin, Marc

    2008-11-01

    A set of experiments have been conducted at the US Navy's Large Cavitation Channel to investigate skin-friction drag reduction with the injection of air into a high Reynolds number turbulent boundary layer. Testing was performed on a 12.9 m long flat-plate test model with the surface hydraulically smooth and fully rough at downstream-distance-based Reynolds numbers to 220 million and at speeds to 20 m/s. Local skin-friction, near-wall bulk void fraction, and near-wall bubble imaging were monitored along the length of the model. The instrument suite was used to access the requirements necessary to achieve air layer drag reduction (ALDR). Injection of air over a wide range of air fluxes showed that three drag reduction regimes exist when injecting air; (1) bubble drag reduction that has poor downstream persistence, (2) a transitional regime with a steep rise in drag reduction, and (3) ALDR regime where the drag reduction plateaus at 90% ± 10% over the entire model length with large void fractions in the near-wall region. These investigations revealed several requirements for ALDR including; sufficient volumetric air fluxes that increase approximately with the square of the free-stream speed, slightly higher air fluxes are needed when the surface tension is reduced, higher air fluxes are required for rough surfaces, and the formation of ALDR is sensitive to the inlet condition.

  12. Dynamical Properties of Vortex Furrows in Transitioning Boundary Layers

    Science.gov (United States)

    Bernard, Peter

    2011-11-01

    A vortex filament simulation of the spatially growing transitional boundary layer reveals the presence of low speed streaks underlying furrow-like streamwise oriented folds in the surface vorticity layer (AIAA J. Vol. 48, 2010; Proc. ETC13, 2011). The putative hairpin vortices and packets widely observed in boundary layers are found to be an illusion created by assigning the status of structure to the visualized form of regions of rotational motion created by the vortex furrows. Thus, at best, hairpins roughly describe the shape taken by that part of the vorticity within the furrows that directly causes rotation while ignoring the ``invisible'' and considerable non-rotational part. The life history of the furrows is discussed here including a description of how they grow and the dynamics of the vorticity field within them. Long lived furrows represent ``factories'' within which initially spanwise vorticity progresses from arch to either one or two-lobed mushroom-like structures in a continuous stream. Furrows grow by this same process. At the heart of the furrow phenomenon is a self-reinforcing process by which streamwise vorticity begets more streamwise vorticity.

  13. Multi-scale model analysis of boundary layer ozone over East Asia

    Directory of Open Access Journals (Sweden)

    M. Lin

    2009-05-01

    Full Text Available This study employs the regional Community Multiscale Air Quality (CMAQ model to examine seasonal and diurnal variations of boundary layer ozone (O3 over East Asia. We evaluate the response of model simulations of boundary layer O3 to the choice of chemical mechanisms, meteorological fields, boundary conditions, and model resolutions. Data obtained from surface stations, aircraft measurements, and satellites are used to advance understanding of O3 chemistry and mechanisms over East Asia and evaluate how well the model represents the observed features. Satellite measurements and model simulations of summertime rainfall are used to assess the impact of the Asian monsoon on O3 production. Our results suggest that summertime O3 over Central Eastern China is highly sensitive to cloud cover and monsoonal rainfall over this region. Thus, accurate simulation of the East Asia summer monsoon is critical to model analysis of atmospheric chemistry over China. Examination of hourly summertime O3 mixing ratios from sites in Japan confirms the important role of diurnal boundary layer fluctuations in controlling ground-level O3. By comparing five different model configurations with observations at six sites, the specific mechanisms responsible for model behavior are identified and discussed. In particular, vertical mixing, urban chemistry, and dry deposition depending on boundary layer height strongly affect model ability to capture observed behavior. Central Eastern China appears to be the most sensitive region in our study to the choice of chemical mechanisms. Evaluation with TRACE-P aircraft measurements reveals that neither the CB4 nor the SAPRC99 mechanisms consistently capture observed behavior of key photochemical oxidants in springtime. However, our analysis finds that SAPRC99 performs somewhat better in simulating mixing ratios of H2O2 (hydrogen peroxide

  14. Discovery of jarosite within the Mawrth Vallis region of Mars: Implications for the geologic history of the region

    Science.gov (United States)

    Farrand, W. H.; Glotch, T.D.; Rice, J. W.; Hurowitz, J.A.; Swayze, G.A.

    2009-01-01

    Analysis of visible to near infrared reflectance data from the MRO CRISM hyperspectral imager has revealed the presence of an ovoid-shaped landform, approximately 3 by 5 km in size, within the layered terrains surrounding the Mawrth Vallis outflow channel. This feature has spectral absorption features consistent with the presence of the ferric sulfate mineral jarosite, specifically a K-bearing jarosite (KFe3(SO4)2(OH)6). Terrestrial jarosite is formed through the oxidation of iron sulfides in acidic environments or from basaltic precursor minerals with the addition of sulfur. Previously identified phyllosilicates in the Mawrth Vallis layered terrains include a basal sequence of layers containing Fe-Mg smectites and an upper set of layers of hydrated silica and aluminous phyllosilicates. In terms of its fine scale morphology revealed by MRO HiRISE imagery, the jarosite-bearing unit has fracture patterns very similar to that observed in Fe-Mg smectite-bearing layers, but unlike that observed in the Al-bearing phyllosilicate unit. The ovoid-shaped landform is situated in an east-west bowl-shaped depression superposed on a north sloping surface. Spectra of the ovoid-shaped jarosite-bearing landform also display an anomalously high 600 nm shoulder, which may be consistent with the presence of goethite and a 1.92 ??m absorption which could indicate the presence of ferrihydrite. Goethite, jarosite, and ferrihydrite can be co-precipitated and/or form through transformation of schwertmannite, both processes generally occurring under low pH conditions (pH 2-4). To date, this location appears to be unique in the Mawrth Vallis region and could represent precipitation of jarosite in acidic, sulfur-rich ponded water during the waning stages of drying. ?? 2009 Elsevier Inc. All rights reserved.

  15. Discovery of jarosite within the Mawrth Vallis region of Mars: Implications for the geologic history of the region

    Science.gov (United States)

    Farrand, William H.; Glotch, Timothy D.; Rice, James W.; Hurowitz, Joel A.; Swayze, Gregg A.

    2009-12-01

    Analysis of visible to near infrared reflectance data from the MRO CRISM hyperspectral imager has revealed the presence of an ovoid-shaped landform, approximately 3 by 5 km in size, within the layered terrains surrounding the Mawrth Vallis outflow channel. This feature has spectral absorption features consistent with the presence of the ferric sulfate mineral jarosite, specifically a K-bearing jarosite (KFe 3(SO 4) 2(OH) 6). Terrestrial jarosite is formed through the oxidation of iron sulfides in acidic environments or from basaltic precursor minerals with the addition of sulfur. Previously identified phyllosilicates in the Mawrth Vallis layered terrains include a basal sequence of layers containing Fe-Mg smectites and an upper set of layers of hydrated silica and aluminous phyllosilicates. In terms of its fine scale morphology revealed by MRO HiRISE imagery, the jarosite-bearing unit has fracture patterns very similar to that observed in Fe-Mg smectite-bearing layers, but unlike that observed in the Al-bearing phyllosilicate unit. The ovoid-shaped landform is situated in an east-west bowl-shaped depression superposed on a north sloping surface. Spectra of the ovoid-shaped jarosite-bearing landform also display an anomalously high 600 nm shoulder, which may be consistent with the presence of goethite and a 1.92 μm absorption which could indicate the presence of ferrihydrite. Goethite, jarosite, and ferrihydrite can be co-precipitated and/or form through transformation of schwertmannite, both processes generally occurring under low pH conditions (pH 2-4). To date, this location appears to be unique in the Mawrth Vallis region and could represent precipitation of jarosite in acidic, sulfur-rich ponded water during the waning stages of drying.

  16. Analyses of erosion and re-deposition layers on graphite tiles used in the W-shaped divertor region of JT-60U

    International Nuclear Information System (INIS)

    Gotoh, Y.; Yagyu, J.; Masaki, K.; Kizu, K.; Kaminaga, A.; Kodama, K.; Arai, T.; Tanabe, T.; Miya, N.

    2003-01-01

    Erosion and re-deposition profiles were studied on graphite tiles used in the W-shaped divertor of JT-60U in June 1997-October 1998 periods, operated with all-carbon walls with boronizations and inner-private flux pumping. Continuous re-deposition layers were found neither on the dome top nor on the outer wing, while re-deposition layers of around 20 μm thickness were found on the inner wing, in the region close to the dome top. On the outer divertor target, erosion was found to be dominant: maximum erosion depth of around 20 μm was measured, while on the inner target, re-deposition was dominant: columnar structure layers of maximum thickness at around 30 μm on the inner zone while laminar/columnar-layered structures of maximum thickness around 60 μm were found on the outer zone. Poloidal distributions of the erosion depth/re-deposition layer thickness were well correlated with the frequency histograms of strike point position, which were weighted with total power of neutral beam injection, on both the outer and inner targets. Through X-ray photoelectron spectroscopy, composition of the re-deposition layers at a mid zone on the inner target were 3-4 at.% B and <0.6 at.% O, Fe, Cr, and Ni with remaining C. Boron atoms are mostly bound to C atoms but some may precipitated as boron

  17. Water mass characteristic in the outflow region of the Indonesian throughflow during and post 2016 negative Indian ocean dipole event

    Science.gov (United States)

    Bayhaqi, A.; Iskandar, I.; Surinati, D.; Budiman, A. S.; Wardhana, A. K.; Dirhamsyah; Yuan, D.; Lestari, D. O.

    2018-05-01

    Strong El Niño and positive Indian Ocean Dipole (pIOD) events in 2015/2016 followed by relatively strong negative Indian Ocean Dipole (nIOD) and weak La Niña in 2016 events have affected hydrography conditions in the Indonesian Throughflow (ITF) region. Two research cruises were conducted using RV Baruna Jaya VIII in August and November 2016. These cruises aim to evaluate possible impact of those two climate mode events on the water mass characteristic in the outflow region of the ITF. Hydrographic data from those two cruises were combined with the sea surface temperature (SST) from the Advanced Very High Resolution Radiometer (AVHRR) and surface wind data from the European Centre for Medium-Range Weather Forecasts (ECMWF). The results showed that in the 2016 anomaly year, the cooler sea surface temperature was observed during the negative IOD (nIOD) event while the warmer temperature was found in the post of nIOD event. The observed water mass characteristics in the outflow region of the ITF revealed that the upper layer was dominated by the Indian Ocean water mass, while the Pacific Ocean water mass was observed in the deeper layer. The observed current data across the Sumba Strait showed that the South Java Coastal Current (SJCC) was observed in the upper layer, propagating eastward toward the Savu Sea. A few days later, the observed currents in the upper layer of the Ombai Strait revealed the ITF flow towards the Indian Ocean. Meanwhile, the lower layer showed an eastward flow towards the Ombai Strait.

  18. Snow nitrate photolysis in polar regions and the mid-latitudes: Impact on boundary layer chemistry and implications for ice core records

    Science.gov (United States)

    Zatko, Maria C.

    The formation and recycling of nitrogen oxides (NOx=NO+NO 2) associated with snow nitrate photolysis has important implications for air quality and the preservation of nitrate in ice core records. This dissertation examines snow nitrate photolysis in polar and mid-latitude regions using field and laboratory based observations combined with snow chemistry column models and a global chemical transport model to explore the impacts of snow nitrate photolysis on boundary layer chemistry and the preservation of nitrate in polar ice cores. Chapter 1 describes how a global chemical transport model is used to calculate the photolysis-driven flux and redistribution of nitrogen across Antarctica, and Chapter 2 presents similar work for Greenland. Snow-sourced NOx is most dependent on the quantum yield for nitrate photolysis as well as the concentration of photolabile nitrate and light-absorbing impurities (e.g., black carbon, dust, organics) in snow. Model-calculated fluxes of snow-sourced NOx are similar in magnitude in Antarctica (0.5--7.8x108 molec cm-2 s -1) and Greenland (0.1--6.4x108 molec cm-2 s-1) because both nitrate and light-absorbing impurity concentrations in snow are higher (by factors of 2 and 10, respectively) in Greenland. Snow nitrate photolysis influences boundary layer chemistry and ice-core nitrate preservation less in Greenland compared to Antarctica largely due to Greenland's proximity to NOx-source regions. Chapter 3 describes how a snow chemistry column model combined with chemistry and optical measurements from the Uintah Basin Winter Ozone Study (UBWOS) 2014 is used to calculate snow-sourced NOx in eastern Utah. Daily-averaged fluxes of snow-sourced NOx (2.9x10 7--1.3x108 molec cm-2 s-1) are similar in magnitude to polar snow-sourced NO x fluxes, but are only minor components of the Uintah Basin boundary layer NOx budget and can be neglected when developing ozone reduction strategies for the region. Chapter 4 presents chemical and optical

  19. Retinal Layer Abnormalities as Biomarkers of Schizophrenia.

    Science.gov (United States)

    Samani, Niraj N; Proudlock, Frank A; Siram, Vasantha; Suraweera, Chathurie; Hutchinson, Claire; Nelson, Christopher P; Al-Uzri, Mohammed; Gottlob, Irene

    2018-06-06

    Schizophrenia is associated with several brain deficits, as well as visual processing deficits, but clinically useful biomarkers are elusive. We hypothesized that retinal layer changes, noninvasively visualized using spectral-domain optical coherence tomography (SD-OCT), may represent a possible "window" to these abnormalities. A Leica EnvisuTM SD-OCT device was used to obtain high-resolution central foveal B-scans in both eyes of 35 patients with schizophrenia and 50 demographically matched controls. Manual retinal layer segmentation was performed to acquire individual and combined layer thickness measurements in 3 macular regions. Contrast sensitivity was measured at 3 spatial frequencies in a subgroup of each cohort. Differences were compared using adjusted linear models and significantly different layer measures in patients underwent Spearman Rank correlations with contrast sensitivity, quantified symptoms severity, disease duration, and antipsychotic medication dose. Total retinal and photoreceptor complex thickness was reduced in all regions in patients (P layer (P layer (P layer thickness (R = -.47, P = .005). Our novel findings demonstrate considerable retinal layer abnormalities in schizophrenia that are related to clinical features and visual function. With time, SD-OCT could provide easily-measurable biomarkers to facilitate clinical assessment and further our understanding of the disease.

  20. Two-dimensional perturbations of the accelerated motion of inhomogeneous gas layers and shells in the interstellar medium

    Science.gov (United States)

    Krasnobaev, K. V.; Kotova, G. Yu.; Tagirova, R. R.

    2015-03-01

    The evolution of perturbations in a two-layer spherical shell and a plane layer with a two-step density distribution has been simulated numerically. The clumps formed by instability are shown to have qualitatively different structures, depending on the ratio of the densities in the inner and outer layers of the shell. Inhomogeneities bordered by a dense gas are formed in shells with an outwardly decreasing density. If, however, a denser gas is in the outer layer, then cores surrounded by a more rarefied material appear. These results are used to analyze the expansion of the HII region RCW 82. Since the inhomogeneities observed in the 13CO emission in the outer parts of this region have sharply delineated boundaries, our calculations argue for the model of the expansion of a shell with an outwardly decreasing density. The interaction of an accelerating shell with clumps in front of it has also been investigated. The deformations of a clump during its penetration into the shell and the formation of a groove in the shell gradually fillingwith a cold gas have been revealed. Thereafter, the shell material collapses to form a cumulative jet. As applied to the HII region RCW 82, we conclude that the existence of jets is possible if there are inhomogeneities with a scale of ˜1018 cm in the interstellar medium. The lack of data on such jet flows at the boundary of this region is an additional argument for the model where the inhomogeneous structure of the boundaries is attributable to the development of Rayleigh-Taylor instability.

  1. Large-scale coherent structures of suspended dust concentration in the neutral atmospheric surface layer: A large-eddy simulation study

    Science.gov (United States)

    Zhang, Yangyue; Hu, Ruifeng; Zheng, Xiaojing

    2018-04-01

    Dust particles can remain suspended in the atmospheric boundary layer, motions of which are primarily determined by turbulent diffusion and gravitational settling. Little is known about the spatial organizations of suspended dust concentration and how turbulent coherent motions contribute to the vertical transport of dust particles. Numerous studies in recent years have revealed that large- and very-large-scale motions in the logarithmic region of laboratory-scale turbulent boundary layers also exist in the high Reynolds number atmospheric boundary layer, but their influence on dust transport is still unclear. In this study, numerical simulations of dust transport in a neutral atmospheric boundary layer based on an Eulerian modeling approach and large-eddy simulation technique are performed to investigate the coherent structures of dust concentration. The instantaneous fields confirm the existence of very long meandering streaks of dust concentration, with alternating high- and low-concentration regions. A strong negative correlation between the streamwise velocity and concentration and a mild positive correlation between the vertical velocity and concentration are observed. The spatial length scales and inclination angles of concentration structures are determined, compared with their flow counterparts. The conditionally averaged fields vividly depict that high- and low-concentration events are accompanied by a pair of counter-rotating quasi-streamwise vortices, with a downwash inside the low-concentration region and an upwash inside the high-concentration region. Through the quadrant analysis, it is indicated that the vertical dust transport is closely related to the large-scale roll modes, and ejections in high-concentration regions are the major mechanisms for the upward motions of dust particles.

  2. Modeling a four-layer location-routing problem

    Directory of Open Access Journals (Sweden)

    Mohsen Hamidi

    2012-01-01

    Full Text Available Distribution is an indispensable component of logistics and supply chain management. Location-Routing Problem (LRP is an NP-hard problem that simultaneously takes into consideration location, allocation, and vehicle routing decisions to design an optimal distribution network. Multi-layer and multi-product LRP is even more complex as it deals with the decisions at multiple layers of a distribution network where multiple products are transported within and between layers of the network. This paper focuses on modeling a complicated four-layer and multi-product LRP which has not been tackled yet. The distribution network consists of plants, central depots, regional depots, and customers. In this study, the structure, assumptions, and limitations of the distribution network are defined and the mathematical optimization programming model that can be used to obtain the optimal solution is developed. Presented by a mixed-integer programming model, the LRP considers the location problem at two layers, the allocation problem at three layers, the vehicle routing problem at three layers, and a transshipment problem. The mathematical model locates central and regional depots, allocates customers to plants, central depots, and regional depots, constructs tours from each plant or open depot to customers, and constructs transshipment paths from plants to depots and from depots to other depots. Considering realistic assumptions and limitations such as producing multiple products, limited production capacity, limited depot and vehicle capacity, and limited traveling distances enables the user to capture the real world situations.

  3. Practical layer designs for polarizing beam-splitter cubes.

    Science.gov (United States)

    von Blanckenhagen, Bernhard

    2006-03-01

    Liquid-crystal-on-silicon- (LCoS-) based digital projection systems require high-performance polarizing beam splitters. The classical beam-splitter cube with an immersed interference coating can fulfill these requirements. Practical layer designs can be generated by computer optimization using the classic MacNeille polarizer layer design as the starting layer design. Multilayer structures with 100 nm bandwidth covering the blue, green, or red spectral region and one design covering the whole visible spectral region are designed. In a second step these designs are realized by using plasma-ion-assisted deposition. The performance of the practical beam-splitter cubes is compared with the theoretical performance of the layer designs.

  4. Ionic double layer of atomically flat gold formed on mica templates

    International Nuclear Information System (INIS)

    Chilcott, Terry C.; Wong, Elicia L.S.; Coster, Hans G.L.; Coster, Adelle C.F.; James, Michael

    2009-01-01

    Electrical impedance spectroscopy characterisations of gold surfaces formed on mica templates in contact with potassium chloride electrolytes were performed at the electric potential of zero charge over a frequency range of 6 x 10 -3 to 100 x 10 3 Hz. They revealed constant-phase-angle (CPA) behaviour with a frequency exponent value of 0.96 for surfaces that were also characterised as atomically flat using atomic force microscopy (AFM). As the frequency exponent value was only marginally less than unity, the CPA behaviour yielded a realistic estimate for the capacitance of the ionic double layer. The retention of the CPA behaviour was attributed to specific adsorption of chloride ions which was detected as an adsorption conductance element in parallel with the CPA impedance element. Significant variations in the ionic double layer capacitance as well as the adsorption conductance were observed for electrolyte concentrations ranging from 33 μM to 100 mM, but neither of these variations correlated with concentration. This is consistent with the electrical properties of the interface deriving principally from the inner or Stern region of the double layer.

  5. 2D layered insulator hexagonal boron nitride enabled surface passivation in dye sensitized solar cells.

    Science.gov (United States)

    Shanmugam, Mariyappan; Jacobs-Gedrim, Robin; Durcan, Chris; Yu, Bin

    2013-11-21

    A two-dimensional layered insulator, hexagonal boron nitride (h-BN), is demonstrated as a new class of surface passivation materials in dye-sensitized solar cells (DSSCs) to reduce interfacial carrier recombination. We observe ~57% enhancement in the photo-conversion efficiency of the DSSC utilizing h-BN coated semiconductor TiO2 as compared with the device without surface passivation. The h-BN coated TiO2 is characterized by Raman spectroscopy to confirm the presence of highly crystalline, mixed monolayer/few-layer h-BN nanoflakes on the surface of TiO2. The passivation helps to minimize electron-hole recombination at the TiO2/dye/electrolyte interfaces. The DSSC with h-BN passivation exhibits significantly lower dark saturation current in the low forward bias region and higher saturation in the high forward bias region, respectively, suggesting that the interface quality is largely improved without impeding carrier transport at the material interface. The experimental results reveal that the emerging 2D layered insulator could be used for effective surface passivation in solar cell applications attributed to desirable material features such as high crystallinity and self-terminated/dangling-bond-free atomic planes as compared with high-k thin-film dielectrics.

  6. One-dimensional conduction through supporting electrolytes: two-scale cathodic Debye layer.

    Science.gov (United States)

    Almog, Yaniv; Yariv, Ehud

    2011-10-01

    Supporting-electrolyte solutions comprise chemically inert cations and anions, produced by salt dissolution, together with a reactive ionic species that may be consumed and generated on bounding ion-selective surfaces (e.g., electrodes or membranes). Upon application of an external voltage, a Faraday current is thereby established. It is natural to analyze this ternary-system process through a one-dimensional transport problem, employing the thin Debye-layer limit. Using a simple model of ideal ion-selective membranes, we have recently addressed this problem for moderate voltages [Yariv and Almog, Phys. Rev. Lett. 105, 176101 (2010)], predicting currents that scale as a fractional power of Debye thickness. We address herein the complementary problem of moderate currents. We employ matched asymptotic expansions, separately analyzing the two inner thin Debye layers adjacent to the ion-selective surfaces and the outer electroneutral region outside them. A straightforward calculation following comparable singular-perturbation analyses of binary systems is frustrated by the prediction of negative ionic concentrations near the cathode. Accompanying numerical simulations, performed for small values of Debye thickness, indicate a number unconventional features occurring at that region, such as inert-cation concentration amplification and electric-field intensification. The current-voltage correlation data of the electrochemical cell, obtained from compilation of these simulations, does not approach a limit as the Debye thickness vanishes. Resolution of these puzzles reveals a transformation of the asymptotic structure of the cathodic Debye layer. This reflects the emergence of an internal boundary layer, adjacent to the cathode, wherein field and concentration scaling differs from those of the Gouy-Chapman theory. The two-scale feature of the cathodic Debye layer is manifested through a logarithmic voltage scaling with Debye thickness. Accounting for this scaling, the

  7. Layer-by-layer modification of thin-film metal-semiconductor multilayers with ultrashort laser pulses

    Science.gov (United States)

    Romashevskiy, S. A.; Tsygankov, P. A.; Ashitkov, S. I.; Agranat, M. B.

    2018-05-01

    The surface modifications in a multilayer thin-film structure (50-nm alternating layers of Si and Al) induced by a single Gaussian-shaped femtosecond laser pulse (350 fs, 1028 nm) in the air are investigated by means of atomic-force microscopy (AFM), scanning electron microscopy (SEM), and optical microscopy (OM). Depending on the laser fluence, various modifications of nanometer-scale metal and semiconductor layers, including localized formation of silicon/aluminum nanofoams and layer-by-layer removal, are found. While the nanofoams with cell sizes in the range of tens to hundreds of nanometers are produced only in the two top layers, layer-by-layer removal is observed for the four top layers under single pulse irradiation. The 50-nm films of the multilayer structure are found to be separated at their interfaces, resulting in a selective removal of several top layers (up to 4) in the form of step-like (concentric) craters. The observed phenomenon is associated with a thermo-mechanical ablation mechanism that results in splitting off at film-film interface, where the adhesion force is less than the bulk strength of the used materials, revealing linear dependence of threshold fluences on the film thickness.

  8. Polarized dependence of nonlinear susceptibility in a single layer graphene system in infrared region

    Energy Technology Data Exchange (ETDEWEB)

    Solookinejad, G., E-mail: ghsolooki@gmail.com

    2016-09-15

    In this study, the linear and nonlinear susceptibility of a single-layer graphene nanostructure driven by a weak probe light and an elliptical polarized coupling field is discussed theoretically. The Landau levels of graphene can be separated in infrared or terahertz regions under the strong magnetic field. Therefore, by using the density matrix formalism in quantum optic, the linear and nonlinear susceptibility of the medium can be derived. It is demonstrated that by adjusting the elliptical parameter, one can manipulate the linear and nonlinear absorption as well as Kerr nonlinearity of the medium. It is realized that the enhanced Kerr nonlinearity can be possible with zero linear absorption and nonlinear amplification at some values of elliptical parameter. Our results may be having potential applications in quantum information science based on Nano scales devices.

  9. Characterization of Nitride Layers Formed by Nitrogen Ion Implantation into Surface Region of Iron

    International Nuclear Information System (INIS)

    Sudjatmoko; Subki, M. Iyos R.

    2000-01-01

    Ion implantation is a convenient means of modifying the physical and chemical properties of the near-surface region of materials. The nitrogen implantation into pure iron has been performed at room temperature with ion dose of 1.310 17 to 1.310 18 ions/cm 2 and ion energy of 20 to 100 keV. The optimum dose of nitrogen ions implanted into pure iron was around 2.2310 17 ions/cm 2 in order to get the maximum wear resistant. SEM micrographs and EDX show that the nitride layers were found on the surface of substrate. The nitrogen concentration profile was measured using EDX in combination with spot technique, and it can be shown that the depth profile of nitrogen implanted into substrate was nearly Gaussian. (author)

  10. Layers in the Central Orion Nebula

    Science.gov (United States)

    O'Dell, C. R.

    2018-04-01

    The existence of multiple layers in the inner Orion Nebula has been revealed using data from an Atlas of spectra at 2″ and 12 km s-1 resolution. These data were sometimes grouped over Samples of 10″×10″ to produce high Signal to Noise spectra and sometimes grouped into sequences of pseudo-slit Spectra of 12{^''.}8 - 39″width for high spatial resolution studies. Multiple velocity systems were found: V_{MIF} traces the Main Ionization Front (MIF), V_{scat} arises from back-scattering of V_{MIF} emission by particles in the background Photon Dissociation Region (PDR), V_{low} is an ionized layer in front of the MIF and if it is the source of the stellar absorption lines seen in the Trapezium stars, it must lie between the foreground Veil and those stars, V_{new,[O III]} may represent ionized gas evaporating from the Veil away from the observer. There are features such as the Bright Bar where variations of velocities are due to changing tilts of the MIF, but velocity changes above about 25″ arise from variations in velocity of the background PDR. In a region 25″ ENE of the Orion-S Cloud one finds dramatic changes in the [O III] components, including the signals from the V_{low,[O III]} and V_{MIF,[O III]} becoming equal, indicating shadowing of gas from stellar photons of >24.6 eV. This feature is also seen in areas to the west and south of the Orion-S Cloud.

  11. Identifying revealed comparative advantages in an EU regional context

    OpenAIRE

    Cordes, Alexander; Gehrke, Birgit; Römisch, Roman; Rammer, Christian; Schliessler, Paula; Wassmann, Pia

    2015-01-01

    [Introduction ...] Overall, this report is structured as follows: the next chapter (2) briefly outlines the relevance of regional trade indicators for determining the competitiveness of a region. In chapter 3, the methodology for the calculation of regional trade performance indicators is introduced, and the elementary results are described. Chapter 4 presents an econometric analysis relating key regional characteristics to international success of local industries. Based upon the regional di...

  12. Sources and Transport of Aerosol above the Boundary Layer over the Mediterranean Basin

    Science.gov (United States)

    Roberts, Greg; Corrigan, Craig; Ritchie, John; Pont, Veronique; Claeys, Marine; Sciare, Jean; Mallet, Marc; Dulac, François; Mihalopoulos, Nikos

    2015-04-01

    The Mediterranean Region has been identified as sensitive to changes in the hydrological cycle, which could affect the water resources for millions of people by the turn of the century. However, prior to recent observations, most climate models have not accounted for the impacts of aerosol in this region. Past airborne studies have shown that aerosol sources from Europe and Africa are often transported throughout the lower troposphere; yet, because of their complex vertical distribution, it is a challenge to capture the variability and quantify the contribution of these sources to the radiative budget and precipitation processes. The PAEROS ChArMEx Mountain Experiment (PACMEx) complemented the regional activities by collecting aerosol data from atop a mountain on the island of Corsica, France in order to assess boundary layer / free troposphere atmospheric processes. In June/July 2013, PACMEx instruments were deployed at 2000 m.asl near the center of Corsica, France to complement ground-based aerosol observations at 550 m.asl on the northern peninsula, as well as airborne measurements. Comparisons between the peninsula site and the mountain site show similar general trends in aerosol properties; yet, differences in aerosol properties reveal the myriad transport mechanisms over the Mediterranean Basin. Using aerosol physicochemical data coupled with back trajectory analysis, different sources have been identified including Saharan dust transport, residual dust mixed with sea salt, anthropogenic emissions from Western Europe, and a period of biomass burning from Eastern Europe. Each period exhibits distinct signatures in the aerosol related to transport processes above and below the boundary layer. In addition, the total aerosol concentrations at the mountain site revealed a strong diurnal cycling the between the atmospheric boundary layer and the free troposphere, which is typical of mountain-top observations. PACMEx was funded by the National Science Foundation

  13. Distinct summer and winter bacterial communities in the active layer of Svalbard permafrost revealed by DNA- and RNA-based analyses

    Science.gov (United States)

    Schostag, Morten; Stibal, Marek; Jacobsen, Carsten S.; Bælum, Jacob; Taş, Neslihan; Elberling, Bo; Jansson, Janet K.; Semenchuk, Philipp; Priemé, Anders

    2015-01-01

    The active layer of soil overlaying permafrost in the Arctic is subjected to dramatic annual changes in temperature and soil chemistry, which likely affect bacterial activity and community structure. We studied seasonal variations in the bacterial community of active layer soil from Svalbard (78°N) by co-extracting DNA and RNA from 12 soil cores collected monthly over a year. PCR amplicons of 16S rRNA genes (DNA) and reverse transcribed transcripts (cDNA) were quantified and sequenced to test for the effect of low winter temperature and seasonal variation in concentration of easily degradable organic matter on the bacterial communities. The copy number of 16S rRNA genes and transcripts revealed no distinct seasonal changes indicating potential bacterial activity during winter despite soil temperatures well below −10°C. Multivariate statistical analysis of the bacterial diversity data (DNA and cDNA libraries) revealed a season-based clustering of the samples, and, e.g., the relative abundance of potentially active Cyanobacteria peaked in June and Alphaproteobacteria increased over the summer and then declined from October to November. The structure of the bulk (DNA-based) community was significantly correlated with pH and dissolved organic carbon, while the potentially active (RNA-based) community structure was not significantly correlated with any of the measured soil parameters. A large fraction of the 16S rRNA transcripts was assigned to nitrogen-fixing bacteria (up to 24% in June) and phototrophic organisms (up to 48% in June) illustrating the potential importance of nitrogen fixation in otherwise nitrogen poor Arctic ecosystems and of phototrophic bacterial activity on the soil surface. PMID:25983731

  14. Small scale structure in the wall region of a turbulent boundary layer

    International Nuclear Information System (INIS)

    Bogar, T.J.

    1975-01-01

    This paper is a report of the construction and application of an extremely small hot-wire X-probe (typical dimensions of 100 μ) to the measurement of Reynolds stress in the wall region of the turbulent boundary layer of a flat plate at high Reynolds number (Re/sub theta/ = 11,300). In the present flow, the size of the probe corresponds to a dimensionless length based on wall parameters of lu/sub tau//ν = 3. Probe construction methods are described. The Wyngaard-Lumley constant temperature anemometer used to heat the wire is analyzed, and a direct acoustical frequency calibration of the wire is made. This calibration shows the small wire to have uniform frequency response to 15 kHz. A novel calibration technique is employed using a high speed, digital mini-computer to determine the velocity in the stream direction and in a direction normal to the wall by matching the unique voltage pairs produced by the X-wire array in a turbulent flow to the voltage pairs produced when the probe is exposed to a known uniform flow inclined at various angles

  15. Freestanding films of crosslinked gold nanoparticles prepared via layer-by-layer spin-coating

    Science.gov (United States)

    Schlicke, Hendrik; Schröder, Jan H.; Trebbin, Martin; Petrov, Alexey; Ijeh, Michael; Weller, Horst; Vossmeyer, Tobias

    2011-07-01

    A new, extremely efficient method for the fabrication of films comprised of gold nanoparticles (GNPs) crosslinked by organic dithiols is presented in this paper. The method is based on layer-by-layer spin-coating of both components, GNPs and crosslinker, and enables the deposition of films several tens of nanometers in thickness within a few minutes. X-ray diffraction and conductance measurements reveal the proper adjustment concentration of the crosslinker solution of the critical is in order to prevent the destabilization and coalescence of particles. UV/vis spectroscopy, atomic force microscopy, and conductivity measurements indicate that films prepared via layer-by-layer spin-coating are of comparable quality to coatings prepared via laborious layer-by-layer self-assembly using immersion baths. Because spin-coated films are not bound chemically to the substrate, they can be lifted-off by alkaline underetching and transferred onto 3d-electrodes to produce electrically addressable, freely suspended films. Comparative measurements of the sheet resistances indicate that the transfer process does not compromise the film quality.

  16. Freestanding films of crosslinked gold nanoparticles prepared via layer-by-layer spin-coating

    International Nuclear Information System (INIS)

    Schlicke, Hendrik; Schroeder, Jan H; Trebbin, Martin; Petrov, Alexey; Ijeh, Michael; Weller, Horst; Vossmeyer, Tobias

    2011-01-01

    A new, extremely efficient method for the fabrication of films comprised of gold nanoparticles (GNPs) crosslinked by organic dithiols is presented in this paper. The method is based on layer-by-layer spin-coating of both components, GNPs and crosslinker, and enables the deposition of films several tens of nanometers in thickness within a few minutes. X-ray diffraction and conductance measurements reveal the proper adjustment concentration of the crosslinker solution of the critical is in order to prevent the destabilization and coalescence of particles. UV/vis spectroscopy, atomic force microscopy, and conductivity measurements indicate that films prepared via layer-by-layer spin-coating are of comparable quality to coatings prepared via laborious layer-by-layer self-assembly using immersion baths. Because spin-coated films are not bound chemically to the substrate, they can be lifted-off by alkaline underetching and transferred onto 3d-electrodes to produce electrically addressable, freely suspended films. Comparative measurements of the sheet resistances indicate that the transfer process does not compromise the film quality.

  17. The influence of double nested layer waviness on compression strength of carbon fiber composite materials

    International Nuclear Information System (INIS)

    Khan, Z.M.

    1997-01-01

    As advanced composite materials having superior physical and mechanical properties are being developed, optimization of their production processes in eagerly being sought. One of the most common defect in production of structural composites is layer waviness. Layer waviness is more pronounced in thick section flat and cylindrical laminates that are extensively used in missile casings, submersibles and space platforms. Layer waviness undulates the entire layers of a multidirectional laminate in through-the-thickness direction leading to gross deterioration of its compression strength. This research investigates the influence of multiple layer waviness in a double nest formation on the compression strength of a composite laminate. Different wave fractions of wave 0 degree centigrade layer fabricated in IM/85510-7 carbon - epoxy composite laminate on a steel mold using single step fabrication procedure. The laminate was cured on a heated press according to specific curing cycle. Static compression testing was performed using NASA short block compression fixture on an MTS servo Hydraulic machine. The purpose of these tests was to determine the effects of multiple layer wave regions on the compression strength of composite laminate. The experimental and analytical results revealed that up to about 35% fraction of wave 0 degree layer exceeded 35%. This analysis indicated that the percentage of 0 degree wavy layer may be used to estimate the reduction in compression strength of a composite laminate under restricted conditions. (author)

  18. Boundary layer flow of an oldroyd-b fluid in the region of stagnation point over a stretching sheet

    International Nuclear Information System (INIS)

    Sajid, M.

    2012-01-01

    The mathematical modeling for the two-dimensional boundary layer flow of an Oldroyd-B fluid is presented. The developed equations are used to discuss the problem of two-dimensional flow in the region of a stagnation point over a stretching sheet. The obtained partial differential equations are reduced to an ordinary differential equation by a suitable transformation. The obtained equation is then solved using a finite difference method. The influence of the pertinent fluid parameters on the velocity is discussed through graphs. The behavior of f (0) is also investigated for the change in parameter values. Our main focus is to discuss the effects of relaxation and retardation time parameters on the velocity components in the x and y directions. In addition to it the skin friction coefficient is evaluated which is a measure of frictional drag at the surface illustrates that the boundary layer thickness decreases due to an increase in the relaxation time constant. The reason is that a higher relaxation time constant give rise to a slower recovery process and as a result the boundary layer thickness grows at a slower rate for a higher value of the relaxation time constant when compared with its lower value. (orig./A.B.)

  19. Bottom-type scattering layers and equatorial spread F

    Directory of Open Access Journals (Sweden)

    D. L. Hysell

    2004-12-01

    Full Text Available Jicamarca radar observations of bottom-type coherent scattering layers in the post-sunset bottomside F-region ionosphere are presented and analyzed. The morphology of the primary waves seen in radar images of the layers supports the hypothesis of kudeki+bhattacharyya-1999 that wind-driven gradient drift instabilities are operating. In one layer event when topside spread F did not occur, irregularities were distributed uniformly in space throughout the layers. In another event when topside spread F did eventually occur, the irregularities within the pre-existing bottom-type layers were horizontally clustered, with clusters separated by about 30km. The same horizontal periodicity was evident in the radar plumes and large-scale irregularities that emerged later in the event. We surmise that horizontal periodicity in bottom-type layer irregularity distribution is indicative of large-scale horizontal waves in the bottomside F-region that may serve as seed waves for large-scale Rayleigh Taylor instabilities. Key words. Ionosphere (equatorial ionosphere; ionospheric irregularties; plasma waves and instabilities

  20. High ion temperatures from buried layers irradiated with Vulcan Petawatt

    International Nuclear Information System (INIS)

    Karsch, S.; Schreiber, J.; Willingale, L.; Lancaster, K.; Habara, H.; Nilson, P.; Gopal, A.; Wei, M. S.; Stoeckl, C.; Evans, R.; Clarke, R.; Heathcote, R.; Najmudin, Z.; Krushelnick, K.; Neely, D.; Norreys, P. A.

    2005-01-01

    Deuteron acceleration from CH/CD/CH layer targets irradiated with PW laser pulses has been studied using. Thomson parabola spectrometers and neutron TOF spectroscopy. The measured ion and neutron spectra reveal significant MeV deuteron acceleration from the deeply buried CD layer, which scales with the thickness of the overlying CH layer. While the neutron spectra reveal the scaling of the thermal heating with target thickness, the ion spectra indicate the presence of an efficient nonthermal acceleration mechanism inside. the bulk. Possible explanations will be discussed. (Author)

  1. Timing of isoclinal folds in multiply deformed high metamorphic grade region using FIA succession

    Science.gov (United States)

    Cao, Hui; Cai, Zhihui

    2013-04-01

    Multiply deformed and isoclinally folded interlayered high metamorphic grade gneisses and schists can be very difficult rocks for resolving early formed stratigraphic and structural relationships. When such rocks contain porphyroblasts a new approach is possible because of the way in which porphyroblast growth is affected by crenulation versus reactivation of compositional layering. The asymmetries of the overprinting foliations preserved as inclusion trails that define the FIAs can be used to investigate whether an enigmatic isoclinal fold is an antiform or synform. This approach also reveals when the fold first formed during the tectonic history of the region. Isoclinally folded rocks in the Arkansas River region of Central Colorado contain relics of fold hinges that have been very difficult to ascertain whether they are antiforms or synforms because of younger refolding effects and the locally truncated nature of coarse compositional layering. With the realization that rocks with a schistosity parallel to bedding (S0 parallel S1) have undergone lengthy histories of deformation that predate the obvious first deformation came recognition that large scale regional folds can form early during this process and be preserved throughout orogenesis. This extensive history is lost within the matrix because of reactivational shear on the compositional layering. However, it can be extracted by measuring FIAs. Recent work using this approach has revealed that the trends of axial planes of all map scale folds, when plotted on a rose diagram, strikingly reflect the FIA trends. That is, although it was demonstrated that the largest scale regional folds commonly form early in the total history, other folds can form and be preserved from subsequent destruction in the strain shadows of plutons or through the partitioning of deformation due to heterogeneities at depth.

  2. Layer-by-layer self-assembled active electrodes for hybrid photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Kniprath, Rolf

    2008-11-18

    Solar cells based on thin organic/inorganic heterofilms are currently in the focus of research, since they represent promising candidates for cost-efficient photovoltaic energy conversion. In this type of cells, charges are separated at a heterointerface between dissimilar electrode materials. These materials either absorb light themselves, or they are sensitized by an additional absorber layer at the interface. The present work investigates photovoltaic cells which are composed of nanoporous TiO{sub 2} combined with conjugated polymers and semiconductor quantum dots (QDs). The method of layer-by-layer self-assembly of oppositely charged nanoparticles and polymers is used for the fabrication of such devices. This method allows to fabricate nanoporous films with controlled thicknesses in the range of a few hundred nanometers to several micrometers. Investigations with scanning electron (SEM) and atomic force microscopy (AFM) reveal that the surface morphology of the films depends only on the chemical structure of the polyions used in the production process, and not on their molecular weight or conformation. From dye adsorption at the internal surface of the electrodes one can estimate that the internal surface area of a 1 {mu}m thick film is up to 120 times larger than the projection plane. X-ray photoelectron spectroscopy (XPS) is used to demonstrate that during the layer-by-layer self-assembly at least 40% of the TiO{sub 2} surface is covered with polymers. This feature allows to incorporate polythiophene derivatives into the films and to use them as sensitizers for TiO{sub 2}. Further, electrodes containing CdSe or CdTe quantum dots (QDs) as sensitizers are fabricated. For the fabrication of photovoltaic cells the layer-by-layer grown films are coated with an additional polymer layer, and Au back electrodes are evaporated on top. The cells are illuminated through transparent doped SnO{sub 2} front electrodes. The I/V curves of all fabricated cells show diode

  3. Epitaxial growth of ZnO layers on (111) GaAs substrates by laser molecular beam epitaxy

    International Nuclear Information System (INIS)

    Ding Jian; Zhang Di; Konomi, Takaharu; Saito, Katsuhiko; Guo Qixin

    2012-01-01

    ZnO layers were grown on (111) GaAs substrates by laser molecular epitaxy at substrate temperatures between 200 and 550 °C. X-ray diffraction analysis revealed that c-axis of ZnO epilayer with a wurtzite structure is perpendicular to the substrate surface. X-ray rocking curves and Raman spectroscopy showed that the crystal quality of ZnO epilayers depends on the substrate temperature during the growth. Strong near-band-edge emission in the UV region without any deep-level emissions was observed from the ZnO epilayers at room temperature. The results indicate that laser molecular beam epitaxy is a promising growth method for obtaining high-quality ZnO layers on (111) GaAs substrates.

  4. A broadband metamaterial absorber based on multi-layer graphene in the terahertz region

    Science.gov (United States)

    Fu, Pan; Liu, Fei; Ren, Guang Jun; Su, Fei; Li, Dong; Yao, Jian Quan

    2018-06-01

    A broadband metamaterial absorber, composed of the periodic graphene pattern on SiO2 dielectric with the double layer graphene films inserted in it and all of them backed by metal plan, is proposed and investigated. The simulation results reveal that the wide absorption band can be flexibly tuned between the low-frequency band and the high-frequency band by adjusting graphene's Fermi level. The absorption can achieve 90% in 5.50-7.10 THz, with Fermi level of graphene is 0.3 eV, while in 6.98-9.10 THz with Fermi level 0.6 eV. Furthermore, the proposed structure can be switched from reflection (>81%) to absorption (>90%) over the whole operation band, when the Fermi level of graphene varies from 0 to 0.6 eV. Besides, the proposed absorber is insensitive to the polarization and can work over a wide range of incident angle. Compared with the previous broadband absorber, our graphene based wideband terahertz absorber can enable a wide application of high performance terahertz devices, including sensors, imaging devices and electro-optic switches.

  5. Structure and Evolution of the Lunar Procellarum Region as Revealed by GRAIL Gravity Data

    Science.gov (United States)

    Andrews-Hanna, Jeffrey C.; Besserer, Jonathan; Head, James W., III; Howett, Carly J. A.; Kiefer, Walter S.; Lucey, Paul J.; McGovern, Patrick J.; Melosh, H. Jay; Neumann, Gregory A.; Phillips, Roger J.; hide

    2014-01-01

    The Procellarum region is a broad area on the nearside of the Moon that is characterized by low elevations, thin crust, and high surface concentrations of the heat-producing elements uranium, thorium, and potassium. The Procellarum region has been interpreted as an ancient impact basin approximately 3200 km in diameter, though supporting evidence at the surface would have been largely obscured as a result of the great antiquity and poor preservation of any diagnostic features. Here we use data from the Gravity Recovery and Interior Laboratory (GRAIL) mission to examine the subsurface structure of Procellarum. The Bouguer gravity anomalies and gravity gradients reveal a pattern of narrow linear anomalies that border the Procellarum region and are interpreted to be the frozen remnants of lava-filled rifts and the underlying feeder dikes that served as the magma plumbing system for much of the nearside mare volcanism. The discontinuous surface structures that were earlier interpreted as remnants of an impact basin rim are shown in GRAIL data to be a part of this continuous set of quasi-rectangular border structures with angular intersections, contrary to the expected circular or elliptical shape of an impact basin. The spatial pattern of magmatic-tectonic structures bounding Procellarum is consistent with their formation in response to thermal stresses produced by the differential cooling of the province relative to its surroundings, coupled with magmatic activity driven by the elevated heat flux in the region.

  6. A scenario of vehicle-to-grid implementation and its double-layer optimal charging strategy for minimizing load variance within regional smart grids

    International Nuclear Information System (INIS)

    Jian, Linni; Zhu, Xinyu; Shao, Ziyun; Niu, Shuangxia; Chan, C.C.

    2014-01-01

    Highlights: • A scenario of vehicle-to-grid implementation within regional smart grid is discussed and mathematically formulated. • A double-layer optimal charging strategy for plug-in electric vehicles is proposed. • The proposed double-layer optimal charging algorithm aims to minimize power grid’s load variance. • The performance of proposed double-layer optimal charging algorithm is evaluated through comparative study. - Abstract: As an emerging new electrical load, plug-in electric vehicles (PEVs)’ impact on the power grid has drawn increasing attention worldwide. An optimal scenario is that by digging the potential of PEVs as a moveable energy storage device, they may not harm the power grid by, for example, triggering extreme surges in demand at rush hours, conversely, the large-scale penetration of PEVs could benefit the grid through flattening the power load curve, hence, increase the stability, security and operating economy of the grid. This has become a hot issue which is known as vehicle-to-grid (V2G) technology within the framework of smart grid. In this paper, a scenario of V2G implementation within regional smart grids is discussed. Then, the problem is mathematically formulated. It is essentially an optimization problem, and the objective is to minimize the overall load variance. With the increase of the scale of PEVs and charging posts involved, the computational complexity will become tremendously high. Therefore, a double-layer optimal charging (DLOC) strategy is proposed to solve this problem. The comparative study demonstrates that the proposed DLOC algorithm can effectively solve the problem of tremendously high computational complexity arising from the large-scaled PEVs and charging posts involved

  7. Revealing the cerebral regions and networks mediating vulnerability to depression: oxidative metabolism mapping of rat brain.

    Science.gov (United States)

    Harro, Jaanus; Kanarik, Margus; Kaart, Tanel; Matrov, Denis; Kõiv, Kadri; Mällo, Tanel; Del Río, Joaquin; Tordera, Rosa M; Ramirez, Maria J

    2014-07-01

    The large variety of available animal models has revealed much on the neurobiology of depression, but each model appears as specific to a significant extent, and distinction between stress response, pathogenesis of depression and underlying vulnerability is difficult to make. Evidence from epidemiological studies suggests that depression occurs in biologically predisposed subjects under impact of adverse life events. We applied the diathesis-stress concept to reveal brain regions and functional networks that mediate vulnerability to depression and response to chronic stress by collapsing data on cerebral long term neuronal activity as measured by cytochrome c oxidase histochemistry in distinct animal models. Rats were rendered vulnerable to depression either by partial serotonergic lesion or by maternal deprivation, or selected for a vulnerable phenotype (low positive affect, low novelty-related activity or high hedonic response). Environmental adversity was brought about by applying chronic variable stress or chronic social defeat. Several brain regions, most significantly median raphe, habenula, retrosplenial cortex and reticular thalamus, were universally implicated in long-term metabolic stress response, vulnerability to depression, or both. Vulnerability was associated with higher oxidative metabolism levels as compared to resilience to chronic stress. Chronic stress, in contrast, had three distinct patterns of effect on oxidative metabolism in vulnerable vs. resilient animals. In general, associations between regional activities in several brain circuits were strongest in vulnerable animals, and chronic stress disrupted this interrelatedness. These findings highlight networks that underlie resilience to stress, and the distinct response to stress that occurs in vulnerable subjects. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Modeling the summertime Arctic cloudy boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Curry, J.A.; Pinto, J.O. [Univ. of Colorado, Boulder, CO (United States); McInnes, K.L. [CSIRO Division of Atmospheric Research, Mordialloc (Australia)

    1996-04-01

    Global climate models have particular difficulty in simulating the low-level clouds during the Arctic summer. Model problems are exacerbated in the polar regions by the complicated vertical structure of the Arctic boundary layer. The presence of multiple cloud layers, a humidity inversion above cloud top, and vertical fluxes in the cloud that are decoupled from the surface fluxes, identified in Curry et al. (1988), suggest that models containing sophisticated physical parameterizations would be required to accurately model this region. Accurate modeling of the vertical structure of multiple cloud layers in climate models is important for determination of the surface radiative fluxes. This study focuses on the problem of modeling the layered structure of the Arctic summertime boundary-layer clouds and in particular, the representation of the more complex boundary layer type consisting of a stable foggy surface layer surmounted by a cloud-topped mixed layer. A hierarchical modeling/diagnosis approach is used. A case study from the summertime Arctic Stratus Experiment is examined. A high-resolution, one-dimensional model of turbulence and radiation is tested against the observations and is then used in sensitivity studies to infer the optimal conditions for maintaining two separate layers in the Arctic summertime boundary layer. A three-dimensional mesoscale atmospheric model is then used to simulate the interaction of this cloud deck with the large-scale atmospheric dynamics. An assessment of the improvements needed to the parameterizations of the boundary layer, cloud microphysics, and radiation in the 3-D model is made.

  9. Enhancing carrier injection in the active region of a 280nm emission wavelength LED using graded hole and electron blocking layers

    KAUST Repository

    Janjua, Bilal; Ng, Tien Khee; Alyamani, Ahmed Y.; El-Desouki, Munir M.; Ooi, Boon S.

    2014-01-01

    A theoretical investigation of AlGaN UV-LED with band engineering of hole and electron blocking layers (HBL and EBL, respectively) was conducted with an aim to improve injection efficiency and reduce efficiency droop in the UV LEDs. The analysis is based on energy band diagrams, carrier distribution and recombination rates (Shockley-Reed-Hall, Auger, and radiative recombination rates) in the quantum well, under equilibrium and forward bias conditions. Electron blocking layer is based on AlaGa1-aN / Al b → cGa1-b → 1-cN / AldGa 1-dN, where a < d < b < c. A graded layer sandwiched between large bandgap AlGaN materials was found to be effective in simultaneously blocking electrons and providing polarization field enhanced carrier injection. The graded interlayer reduces polarization induced band bending and mitigates the related drawback of impediment of holes injection. Similarly on the n-side, the Alx → yGa1-x → 1-yN / AlzGa 1-zN (x < z < y) barrier acts as a hole blocking layer. The reduced carrier leakage and enhanced carrier density in the active region results in significant improvement in radiative recombination rate compared to a structure with the conventional rectangular EBL layers. The improvement in device performance comes from meticulously designing the hole and electron blocking layers to increase carrier injection efficiency. The quantum well based UV-LED was designed to emit at 280nm, which is an effective wavelength for water disinfection application.

  10. Enhancing carrier injection in the active region of a 280nm emission wavelength LED using graded hole and electron blocking layers

    KAUST Repository

    Janjua, Bilal

    2014-02-27

    A theoretical investigation of AlGaN UV-LED with band engineering of hole and electron blocking layers (HBL and EBL, respectively) was conducted with an aim to improve injection efficiency and reduce efficiency droop in the UV LEDs. The analysis is based on energy band diagrams, carrier distribution and recombination rates (Shockley-Reed-Hall, Auger, and radiative recombination rates) in the quantum well, under equilibrium and forward bias conditions. Electron blocking layer is based on AlaGa1-aN / Al b → cGa1-b → 1-cN / AldGa 1-dN, where a < d < b < c. A graded layer sandwiched between large bandgap AlGaN materials was found to be effective in simultaneously blocking electrons and providing polarization field enhanced carrier injection. The graded interlayer reduces polarization induced band bending and mitigates the related drawback of impediment of holes injection. Similarly on the n-side, the Alx → yGa1-x → 1-yN / AlzGa 1-zN (x < z < y) barrier acts as a hole blocking layer. The reduced carrier leakage and enhanced carrier density in the active region results in significant improvement in radiative recombination rate compared to a structure with the conventional rectangular EBL layers. The improvement in device performance comes from meticulously designing the hole and electron blocking layers to increase carrier injection efficiency. The quantum well based UV-LED was designed to emit at 280nm, which is an effective wavelength for water disinfection application.

  11. Argon-ion-induced formation of nanoporous GaSb layer: Microstructure, infrared luminescence, and vibrational properties

    Energy Technology Data Exchange (ETDEWEB)

    Datta, D. P.; Som, T., E-mail: tsom@iopb.res.in [SUNAG Laboratory, Institute of Physics, Bhubaneswar, Odisha 751 005 (India); Kanjilal, A. [Department of Physics, Shiv Nadar University, Uttar Pradesh 201 314 (India); Satpati, B. [Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India); Dhara, S. [Surface and Nanoscience Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Das, T. D. [Department of Electronic Science, University of Calcutta, APC Road, Kolkata 700 009 (India); Kanjilal, D. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India)

    2014-07-21

    Room temperature implantation of 60 keV Ar{sup +}-ions in GaSb to the fluences of 7 × 10{sup 16} to 3 × 10{sup 18} ions cm{sup −2} is carried out at two incidence angles, viz 0° and 60°, leading to formation of a nanoporous layer. As the ion fluence increases, patches grow on the porous layer under normal ion implantation, whereas the porous layer gradually becomes embedded under a rough top surface for oblique incidence of ions. Grazing incidence x-ray diffraction and cross-sectional transmission electron microscopy studies reveal the existence of nanocrystallites embedded in the ion-beam amorphized GaSb matrix up to the highest fluence used in our experiment. Oxidation of the nanoporous layers becomes obvious from x-ray photoelectron spectroscopy and Raman mapping. The correlation of ion-beam induced structural modification with photoluminescence signals in the infrared region has further been studied, showing defect induced emission of additional peaks near the band edge of GaSb.

  12. Regional evapotranspiration estimation based on a two-layer remote-sensing scheme in Shahe River basin

    International Nuclear Information System (INIS)

    Yin, Jian; Wang, Huixiao

    2014-01-01

    Land surface evapotranspiration (ET) derived from remote sensing data has significant meaning for plant growth monitoring, crop yield assessment, disaster monitoring and understanding energy and water cycle in river basin area and surrounding regions. In the study, we developed a land surface ET remote sensing retrieval system to estimate the daily ET in Shahe river basin using the TM/ETM+ images. The system is based on the two-layer ET model and includes three parts: inversion of the evaporation ration using two-layer model, calculation of total daily net radiation, and estimation of daily ET based on evaporation fraction method. The results show that the average daily ET is about 2.28mm of the typical days in spring, and 2.97mm in summer, 1.59mm in autumn, and 0.5mm in winter. The ET in upstream areas covered by forest is higher than that in the downstream covered by settlement and farmland. In summer the difference of ET between the upper reaches and lower reaches is smaller compared to the other three seasons. The measurements by large aperture scintillometer and eddy correlation instrument were used for validation. By comparing the observed data with the estimated data, we found the estimation system had a high precision with the relative error between 0 and 16% (mean error of 11.1%), and the variance 0.77mm

  13. Electro-responsivity of ionic liquid boundary layers in a polar solvent revealed by neutron reflectance

    Science.gov (United States)

    Pilkington, Georgia A.; Harris, Kathryn; Bergendal, Erik; Reddy, Akepati Bhaskar; Palsson, Gunnar K.; Vorobiev, Alexei; Antzutkin, Oleg. N.; Glavatskih, Sergei; Rutland, Mark W.

    2018-05-01

    Using neutron reflectivity, the electro-responsive structuring of the non-halogenated ionic liquid (IL) trihexyl(tetradecyl)phosphonium-bis(mandelato)borate, [P6,6,6,14][BMB], has been studied at a gold electrode surface in a polar solvent. For a 20% w/w IL mixture, contrast matched to the gold surface, distinct Kiessig fringes were observed for all potentials studied, indicative of a boundary layer of different composition to that of the bulk IL-solvent mixture. With applied potential, the amplitudes of the fringes from the gold-boundary layer interface varied systematically. These changes are attributable to the differing ratios of cations and anions in the boundary layer, leading to a greater or diminished contrast with the gold electrode, depending on the individual ion scattering length densities. Such electro-responsive changes were also evident in the reflectivities measured for the pure IL and a less concentrated (5% w/w) IL-solvent mixture at the same applied potentials, but gave rise to less pronounced changes. These measurements, therefore, demonstrate the enhanced sensitivity achieved by contrast matching the bulk solution and that the structure of the IL boundary layers formed in mixtures is strongly influenced by the bulk concentration. Together these results represent an important step in characterising IL boundary layers in IL-solvent mixtures and provide clear evidence of electro-responsive structuring of IL ions in their solutions with applied potential.

  14. Mixing processes at the subsurface layer in the Amundsen Sea shelf region

    Science.gov (United States)

    Mojica, J.; Djoumna, G.; Francis, D. K.; Holland, D.

    2017-12-01

    In the Amundsen Sea shelf region, mixing processes promote an upward transport of diapycnal fluxes of heat and salt from the subsurface to the surface mixing layer. Here we estimate the diapycnal mixing rates on the Amundsen shelf from a multi-year mooring cluster and five research cruises. By applying fine-scale parameterizations, the mixing rates obtained were higher near the southern end of Pine Island glacier front and exceeded 10-2 m2s-1. The eddy diffusivity increased near the critical latitude (74o 28' S) for semi-diurnal M2 tides, which coincided with near-critical topography on the shelf. This condition favored the generation of internal waves of M2 frequency. The semi-diurnal dynamic enhanced the mixing that potentially affected the heat budget and the circulation of the modified Circumpolar Deep Water. This can be observed in the characteristics of water exchange both below the ice shelves and between the continental shelf and the ice shelf cavities. The location of the critical latitude and critical topography provided favorable conditions for the generation of internal waves. KEYWORDS: Mixing processes, diapycnal fluxes, critical latitude, Circumpolar Deep Water.

  15. Modelling of impurity transport in ergodic layer of LHD

    International Nuclear Information System (INIS)

    Feng, Y.; Masuzaki, S.; Morisaki, T.; Ohyabu, N.; Yamada, H.; Komori, A.; Motojima, O.; Kobayashi, M.

    2008-01-01

    The impurity transport properties in the ergodic layer of LHD are analyzed by the 3D edge transport code as well as 1D simple model, which is used to illustrate the essential transport terms in the analysis. It is found that as the plasma density increases the edge surface layers, very edge region of the ergodic layer, enters friction dominant regime, resulting in impurity retention. It is considered that the cause for the retention is both temperature drop and the flow acceleration in the edge surface layers. The edge surface layers can provide effective retention of impurities coming from divertor as well as the first wall, because of the geometrical advantage of the edge region of LHD. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Surface segregation as a means of gettering Cu in liquid-phase-epitaxy silicon thin layers grown from Al-Cu-Si solutions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, T.H.; Ciszek, T.F.; Reedy, R.; Asher, S.; King, D. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    The authors demonstrate that, by using the natural surface segregation phenomenon, Cu can be gettered to the surface from the bulk of silicon layers so that its concentrations in the liquid-phase-epitaxy (LPE) layers are much lower than its solubility at the layer growth temperature and the reported 10{sup 17} cm{sup {minus}3} degradation threshold for solar-cell performance. Secondary-ion mass spectroscopy (SIMS) analysis indicates that, within a micron-deep sub-surface region, Cu accumulates even in as-grown LPE samples. Slower cooling after growth to room temperature enhances this Cu enrichment. X-ray photoelectron spectroscopy (XPS) measurement shows as much as 3.2% Cu in a surface region of about 50 {Angstrom}. More surface-sensitive, ion-scattering spectroscopy (ISS) analysis further reveals about 7% of Cu at the top surface. These results translate to an areal gettering capacity of about 1.0 x 10{sup 16} cm{sup {minus}2}, which is higher than the available total-area density of Cu in the layer and substrate (3.6 x 10{sup 15} cm{sup {minus}2} for a uniform 1.2 x 10{sup 17}cm{sup {minus}3} Cu throughout the layer and substrate with a total thickness of 300 {mu}m).

  17. Topologically nontrivial quantum layers

    International Nuclear Information System (INIS)

    Carron, G.; Exner, P.; Krejcirik, D.

    2004-01-01

    Given a complete noncompact surface Σ embedded in R 3 , we consider the Dirichlet Laplacian in the layer Ω that is defined as a tubular neighborhood of constant width about Σ. Using an intrinsic approach to the geometry of Ω, we generalize the spectral results of the original paper by Duclos et al. [Commun. Math. Phys. 223, 13 (2001)] to the situation when Σ does not possess poles. This enables us to consider topologically more complicated layers and state new spectral results. In particular, we are interested in layers built over surfaces with handles or several cylindrically symmetric ends. We also discuss more general regions obtained by compact deformations of certain Ω

  18. Altered spontaneous brain activity in adolescent boys with pure conduct disorder revealed by regional homogeneity analysis.

    Science.gov (United States)

    Wu, Qiong; Zhang, Xiaocui; Dong, Daifeng; Wang, Xiang; Yao, Shuqiao

    2017-07-01

    Functional magnetic resonance imaging (fMRI) studies have revealed abnormal neural activity in several brain regions of adolescents with conduct disorder (CD) performing various tasks. However, little is known about the spontaneous neural activity in people with CD in a resting state. The aims of this study were to investigate CD-associated regional activity abnormalities and to explore the relationship between behavioral impulsivity and regional activity abnormalities. Resting-state fMRI (rs-fMRI) scans were administered to 28 adolescents with CD and 28 age-, gender-, and IQ-matched healthy controls (HCs). The rs-fMRI data were subjected to regional homogeneity (ReHo) analysis. ReHo can demonstrate the temporal synchrony of regional blood oxygen level-dependent signals and reflect the coordination of local neuronal activity facilitating similar goals or representations. Compared to HCs, the CD group showed increased ReHo bilaterally in the insula as well as decreased ReHo in the right inferior parietal lobule, right middle temporal gyrus and right fusiform gyrus, left anterior cerebellum anterior, and right posterior cerebellum. In the CD group, mean ReHo values in the left and the right insula correlated positively with Barratt Impulsivity Scale (BIS) total scores. The results suggest that CD is associated with abnormal intrinsic brain activity, mainly in the cerebellum and temporal-parietal-limbic cortices, regions that are related to emotional and cognitive processing. BIS scores in adolescents with CD may reflect severity of abnormal neuronal synchronization in the insula.

  19. Simulation of aerosol nucleation and growth in a turbulent mixing layer

    KAUST Repository

    Zhou, Kun

    2014-06-25

    A large-scale simulation of aerosol nucleation and growth in a turbulent mixing layer is performed and analyzed with the aim of elucidating the key processes involved. A cold gaseous stream is mixed with a hot stream of vapor, nanometer sized droplets nucleate as the vapor becomes supersaturated, and subsequently grow as more vapor condenses on their surface. All length and time scales of fluid motion and mixing are resolved and the quadrature method of moments is used to describe the dynamics of the condensing, non-inertial droplets. The results show that a region of high nucleation rate is located near the cold, dry stream, while particles undergo intense growth via condensation on the hot, humid vapor side. Supersaturation and residence times are such that number densities are low and neither coagulation nor vapor scavenging due to condensation are significant. The difference in Schmidt numbers of aerosol particles (approximated as infinity) and temperature and vapor (near unity) causes a drift of the aerosol particles in scalar space and contributes to a large scatter in the conditional statistics of aerosol quantities. The spatial distribution of the aerosol reveals high volume fraction on the hot side of the mixing layer. This distribution is due to drift against the mean and is related to turbulent mixing, which displaces particles from the nucleation region (cold side) into the growth region (hot side). Such a mechanism is absent in laminar flows and is a distinct feature of turbulent condensing aerosols.

  20. Simulation of aerosol nucleation and growth in a turbulent mixing layer

    KAUST Repository

    Zhou, Kun; Attili, Antonio; Alshaarawi, Amjad; Bisetti, Fabrizio

    2014-01-01

    A large-scale simulation of aerosol nucleation and growth in a turbulent mixing layer is performed and analyzed with the aim of elucidating the key processes involved. A cold gaseous stream is mixed with a hot stream of vapor, nanometer sized droplets nucleate as the vapor becomes supersaturated, and subsequently grow as more vapor condenses on their surface. All length and time scales of fluid motion and mixing are resolved and the quadrature method of moments is used to describe the dynamics of the condensing, non-inertial droplets. The results show that a region of high nucleation rate is located near the cold, dry stream, while particles undergo intense growth via condensation on the hot, humid vapor side. Supersaturation and residence times are such that number densities are low and neither coagulation nor vapor scavenging due to condensation are significant. The difference in Schmidt numbers of aerosol particles (approximated as infinity) and temperature and vapor (near unity) causes a drift of the aerosol particles in scalar space and contributes to a large scatter in the conditional statistics of aerosol quantities. The spatial distribution of the aerosol reveals high volume fraction on the hot side of the mixing layer. This distribution is due to drift against the mean and is related to turbulent mixing, which displaces particles from the nucleation region (cold side) into the growth region (hot side). Such a mechanism is absent in laminar flows and is a distinct feature of turbulent condensing aerosols.

  1. Boosting water oxidation layer-by-layer.

    Science.gov (United States)

    Hidalgo-Acosta, Jonnathan C; Scanlon, Micheál D; Méndez, Manuel A; Amstutz, Véronique; Vrubel, Heron; Opallo, Marcin; Girault, Hubert H

    2016-04-07

    Electrocatalysis of water oxidation was achieved using fluorinated tin oxide (FTO) electrodes modified with layer-by-layer deposited films consisting of bilayers of negatively charged citrate-stabilized IrO2 NPs and positively charged poly(diallyldimethylammonium chloride) (PDDA) polymer. The IrO2 NP surface coverage can be fine-tuned by controlling the number of bilayers. The IrO2 NP films were amorphous, with the NPs therein being well-dispersed and retaining their as-synthesized shape and sizes. UV/vis spectroscopic and spectro-electrochemical studies confirmed that the total surface coverage and electrochemically addressable surface coverage of IrO2 NPs increased linearly with the number of bilayers up to 10 bilayers. The voltammetry of the modified electrode was that of hydrous iridium oxide films (HIROFs) with an observed super-Nernstian pH response of the Ir(III)/Ir(IV) and Ir(IV)-Ir(IV)/Ir(IV)-Ir(V) redox transitions and Nernstian shift of the oxygen evolution onset potential. The overpotential of the oxygen evolution reaction (OER) was essentially pH independent, varying only from 0.22 V to 0.28 V (at a current density of 0.1 mA cm(-2)), moving from acidic to alkaline conditions. Bulk electrolysis experiments revealed that the IrO2/PDDA films were stable and adherent under acidic and neutral conditions but degraded in alkaline solutions. Oxygen was evolved with Faradaic efficiencies approaching 100% under acidic (pH 1) and neutral (pH 7) conditions, and 88% in alkaline solutions (pH 13). This layer-by-layer approach forms the basis of future large-scale OER electrode development using ink-jet printing technology.

  2. Layering spatial identities: the identity discourses of new regions

    NARCIS (Netherlands)

    Terlouw, K.; van Gorp, B.H.

    2014-01-01

    The number and importance of regions are increasing at the same time as traditional regional identities are undermined through processes like globalisation and individualisation. Local and other administrations increasingly cooperate and create new regions which are too changeable for a distinct

  3. Comparison of turbulence in a transitional boundary layer to turbulence in a developed boundary layer*

    Science.gov (United States)

    Park, G. I.; Wallace, J.; Wu, X.; Moin, P.

    2010-11-01

    Using a recent DNS of a flat-plate boundary layer, statistics of turbulence in transition at Reθ= 500 where spots merge (distributions of the mean velocity, rms velocity and vorticity fluctuations, Reynolds shear stress, kinetic energy production and dissipation rates and enstrophy) have been compared to these statistics for the developed boundary layer turbulence at Reθ= 1850. When the distributions in the transitional region, determined in narrow planes 0.03 Reθ wide, exclude regions and times when the flow is not turbulent, they closely resemble those in the developed turbulent state at the higher Reynolds number, especially in the buffer and sublayers. The skin friction coefficient, determined in this conditional manner in the transitional flow is, of course, much larger than that obtained by including both turbulent and non-turbulent information there, and is consistent with a value obtained by extrapolating from the developed turbulent region. We are attempting to perform this data analysis even further upstream in the transitioning flow at Reθ= 300 where the turbulent spots are individuated. These results add further evidence to support the view that the structure of a developed turbulent boundary layer is little different from its structure in its embryonic form in turbulent spots. *CTR 2010 Summer Program research.

  4. Energetics and structure of the lower E region associated with sporadic E layer

    Directory of Open Access Journals (Sweden)

    K.-I. Oyama

    2008-09-01

    Full Text Available The electron temperature (Te, electron density (Ne, and two components of the electric field were measured from the height of 90 km to 150 km by one of the sounding rockets launched during the SEEK-2 campaign. The rocket went through sporadic E layer (Es at the height of 102 km–109 km during ascent and 99 km–108 km during decent, respectively. The energy density of thermal electrons calculated from Ne and Te shows the broad maximum in the height range of 100–110 km, and it decreases towards the lower and higher altitudes, which implies that a heat source exists in the height region of 100 km–110 km. A 3-D picture of Es, that was drawn by using Te, Ne, and the electric field data, corresponded to the computer simulation; the main structure of Es is projected to a higher altitude along the magnetic line of force, thus producing irregular structures of Te, Ne and electric field in higher altitude.

  5. Photoreactive molecular layers containing aryl ester units: Preparation, UV patterning and post-exposure modification

    Energy Technology Data Exchange (ETDEWEB)

    Hoefler, Thomas [Institute for Chemistry and Technology of Materials, Graz University of Technology, Stremayrgasse 16, A-8010 Graz (Austria); Track, Anna M. [Institute of Solid State Physics, Graz University of Technology, Petersgasse 16/II, A-8010 Graz (Austria); Institute of Physics, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria); Pacher, Peter [Institute of Solid State Physics, Graz University of Technology, Petersgasse 16/II, A-8010 Graz (Austria); Shen, Quan [Institute of Physics, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); Flesch, Heinz-Georg [Institute of Solid State Physics, Graz University of Technology, Petersgasse 16/II, A-8010 Graz (Austria); Hlawacek, Gregor [Institute of Physics, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); Koller, Georg; Ramsey, Michael G. [Institute of Physics, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria); Schennach, Robert; Resel, Roland [Institute of Solid State Physics, Graz University of Technology, Petersgasse 16/II, A-8010 Graz (Austria); Teichert, Christian [Institute of Physics, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); Kern, Wolfgang [Institute of Chemistry of Polymers, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); Trimmel, Gregor [Institute for Chemistry and Technology of Materials, Graz University of Technology, Stremayrgasse 16, A-8010 Graz (Austria); Griesser, Thomas, E-mail: thomas.griesser@unileoben.ac.at [Institute for Chemistry and Technology of Materials, Graz University of Technology, Stremayrgasse 16, A-8010 Graz (Austria); Institute of Chemistry of Polymers, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria)

    2010-01-15

    The photolithographic modification of thin functional silane layers provides a versatile and powerful means of fabricating functionalized patterned surfaces which can be applied for tuning inorganic surface properties and for modern immobilisation techniques. In this contribution we present the synthesis of a new functional trichloro organosilane bearing photoreactive aryl ester groups and its application in thin silane layers on silicon oxide surfaces. Whereas the trichlorosilyl group acts as anchoring unit to the inorganic surface, the aryl ester group undergoes the photo-Fries rearrangement to yield hydroxyketones upon irradiation with UV-light of 254 nm which leads to a change in chemical reactivity of the surface. By a subsequent reaction with perfluorobutyryl chloride, the photogenerated hydroxy groups yield the corresponding perfluorinated ester compound, which allows further tuning of surface properties. The layer formation as well as the photoreaction and post-modification reaction was monitored by FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). The thickness of the obtained thin layers was determined by X-ray reflectivity (XRR). Photopatterned surfaces were produced using a contact mask during illumination followed by the post-modification reaction. Friction force microscopy (FFM) revealed the contrast between modified and unmodified regions of the patterned samples.

  6. Structure-guided investigation of lipopolysaccharide O-antigen chain length regulators reveals regions critical for modal length control.

    Science.gov (United States)

    Kalynych, Sergei; Ruan, Xiang; Valvano, Miguel A; Cygler, Miroslaw

    2011-08-01

    The O-antigen component of the lipopolysaccharide (LPS) represents a population of polysaccharide molecules with nonrandom (modal) chain length distribution. The number of the repeat O units in each individual O-antigen polymer depends on the Wzz chain length regulator, an inner membrane protein belonging to the polysaccharide copolymerase (PCP) family. Different Wzz proteins confer vastly different ranges of modal lengths (4 to >100 repeat units), despite having remarkably conserved structural folds. The molecular mechanism responsible for the selective preference for a certain number of O units is unknown. Guided by the three-dimensional structures of PCPs, we constructed a panel of chimeric molecules containing parts of two closely related Wzz proteins from Salmonella enterica and Shigella flexneri which confer different O-antigen chain length distributions. Analysis of the O-antigen length distribution imparted by each chimera revealed the region spanning amino acids 67 to 95 (region 67 to 95), region 200 to 255, and region 269 to 274 as primarily affecting the length distribution. We also showed that there is no synergy between these regions. In particular, region 269 to 274 also influenced chain length distribution mediated by two distantly related PCPs, WzzB and FepE. Furthermore, from the 3 regions uncovered in this study, region 269 to 274 appeared to be critical for the stability of the oligomeric form of Wzz, as determined by cross-linking experiments. Together, our data suggest that chain length determination depends on regions that likely contribute to stabilize a supramolecular complex.

  7. Pitot-probe displacement in a supersonic turbulent boundary layer

    Science.gov (United States)

    Allen, J. M.

    1972-01-01

    Eight circular pitot probes ranging in size from 2 to 70 percent of the boundary-layer thickness were tested to provide experimental probe displacement results in a two-dimensional turbulent boundary layer at a nominal free-stream Mach number of 2 and unit Reynolds number of 8 million per meter. The displacement obtained in the study was larger than that reported by previous investigators in either an incompressible turbulent boundary layer or a supersonic laminar boundary layer. The large probes indicated distorted Mach number profiles, probably due to separation. When the probes were small enough to cause no appreciable distortion, the displacement was constant over most of the boundary layer. The displacement in the near-wall region decreased to negative displacement in some cases. This near-wall region was found to extend to about one probe diameter from the test surface.

  8. Single-layer versus double-layer laparoscopic intracorporeally sutured gastrointestinal anastomoses in the canine model.

    Science.gov (United States)

    Tavakoli, Azine; Bakhtiari, Jalal; Khalaj, Ali Reza; Gharagozlou, Mohammad Javad; Veshkini, Abbas

    2010-01-01

    The objective of this study was to compare the gross and histopathologic changes following 1- versus 2-layer hand-sewn suture techniques in laparoscopic gastrointestinal anastomosis in dogs. This was an experimental prospective study of 16 healthy mixed breed male and female dogs. Animals were randomly divided into 2 groups. Two-layer side-to-side hand-sewn laparoscopic gastrojejunostomies were performed in group A, so that simple interrupted sutures were placed in the outer layer and simple continuous suture was used in the inner layer. The 1-layer simple continuous anastomosis between the stomach and jejunum was done in group B precisely. Specimen were collected from the sites of anastomosis, and H&E statining was performed for light microscopic studies. All animals survived the surgery. There was no gross inflammation, ischemia, apparent granulation tissue, abscess or fistula formation, leakage or stricture formation, and all sites of anastomosis were patent. Several adhesion formations were found in the abdomen with the higher incidence in the control group. Mean scores of leukocyte infiltration and granulation tissue formation at the sites of anastomosis were statistically insignificant between groups (P>0.05). Gross and histopathologic findings revealed that hand-sewn laparoscopic gastrointestinal anastomosis with the 1-layer suture technique is comparable to the 2-layer suture technique.

  9. On efficiently computing multigroup multi-layer neutron reflection and transmission conditions

    International Nuclear Information System (INIS)

    Abreu, Marcos P. de

    2007-01-01

    In this article, we present an algorithm for efficient computation of multigroup discrete ordinates neutron reflection and transmission conditions, which replace a multi-layered boundary region in neutron multiplication eigenvalue computations with no spatial truncation error. In contrast to the independent layer-by-layer algorithm considered thus far in our computations, the algorithm here is based on an inductive approach developed by the present author for deriving neutron reflection and transmission conditions for a nonactive boundary region with an arbitrary number of arbitrarily thick layers. With this new algorithm, we were able to increase significantly the computational efficiency of our spectral diamond-spectral Green's function method for solving multigroup neutron multiplication eigenvalue problems with multi-layered boundary regions. We provide comparative results for a two-group reactor core model to illustrate the increased efficiency of our spectral method, and we conclude this article with a number of general remarks. (author)

  10. Two-Dimensional Layered Oxide Structures Tailored by Self-Assembled Layer Stacking via Interfacial Strain.

    Science.gov (United States)

    Zhang, Wenrui; Li, Mingtao; Chen, Aiping; Li, Leigang; Zhu, Yuanyuan; Xia, Zhenhai; Lu, Ping; Boullay, Philippe; Wu, Lijun; Zhu, Yimei; MacManus-Driscoll, Judith L; Jia, Quanxi; Zhou, Honghui; Narayan, Jagdish; Zhang, Xinghang; Wang, Haiyan

    2016-07-06

    Study of layered complex oxides emerge as one of leading topics in fundamental materials science because of the strong interplay among intrinsic charge, spin, orbital, and lattice. As a fundamental basis of heteroepitaxial thin film growth, interfacial strain can be used to design materials that exhibit new phenomena beyond their conventional forms. Here, we report a strain-driven self-assembly of bismuth-based supercell (SC) with a two-dimensional (2D) layered structure. With combined experimental analysis and first-principles calculations, we investigated the full SC structure and elucidated the fundamental growth mechanism achieved by the strain-enabled self-assembled atomic layer stacking. The unique SC structure exhibits room-temperature ferroelectricity, enhanced magnetic responses, and a distinct optical bandgap from the conventional double perovskite structure. This study reveals the important role of interfacial strain modulation and atomic rearrangement in self-assembling a layered singe-phase multiferroic thin film, which opens up a promising avenue in the search for and design of novel 2D layered complex oxides with enormous promise.

  11. Hierarchical layered and semantic-based image segmentation using ergodicity map

    Science.gov (United States)

    Yadegar, Jacob; Liu, Xiaoqing

    2010-04-01

    Image segmentation plays a foundational role in image understanding and computer vision. Although great strides have been made and progress achieved on automatic/semi-automatic image segmentation algorithms, designing a generic, robust, and efficient image segmentation algorithm is still challenging. Human vision is still far superior compared to computer vision, especially in interpreting semantic meanings/objects in images. We present a hierarchical/layered semantic image segmentation algorithm that can automatically and efficiently segment images into hierarchical layered/multi-scaled semantic regions/objects with contextual topological relationships. The proposed algorithm bridges the gap between high-level semantics and low-level visual features/cues (such as color, intensity, edge, etc.) through utilizing a layered/hierarchical ergodicity map, where ergodicity is computed based on a space filling fractal concept and used as a region dissimilarity measurement. The algorithm applies a highly scalable, efficient, and adaptive Peano- Cesaro triangulation/tiling technique to decompose the given image into a set of similar/homogenous regions based on low-level visual cues in a top-down manner. The layered/hierarchical ergodicity map is built through a bottom-up region dissimilarity analysis. The recursive fractal sweep associated with the Peano-Cesaro triangulation provides efficient local multi-resolution refinement to any level of detail. The generated binary decomposition tree also provides efficient neighbor retrieval mechanisms for contextual topological object/region relationship generation. Experiments have been conducted within the maritime image environment where the segmented layered semantic objects include the basic level objects (i.e. sky/land/water) and deeper level objects in the sky/land/water surfaces. Experimental results demonstrate the proposed algorithm has the capability to robustly and efficiently segment images into layered semantic objects/regions

  12. Revealing the sub-structures of the magnetic reconnection separatrix via particle-in-cell simulation

    International Nuclear Information System (INIS)

    Zhou, M.; Deng, X. H.; Pang, Y.; Xu, X. J.; Yao, M.; Huang, S. Y.; Yuan, Z. G.; Li, H. M.; Wang, D. D.; Wang, Y. H.

    2012-01-01

    Magnetic separatrix is an important boundary layer separating the inflow and outflow regions in magnetic reconnection. In this article, we investigate the sub-structures of the separatrix region by using two-and-half dimensional electromagnetic particle-in-cell simulation. The separatrix region can be divided into two sub-regions in terms of the ion and electron frozen-in conditions. Far from the neutral sheet, ions and electrons are magnetized in magnetic fields. Approaching the neutral sheet, ion frozen-in condition is broken in a narrow region (∼c/ω pi ) at the edge of a density cavity, while electrons are frozen-in to magnetic fields. In this region, electric field E z is around zero, and the convective term –(v i × B) is balanced by the Hall term in the generalized Ohm’s law because ions carry the perpendicular current. Inside the density cavity, both ion and electron frozen-in conditions are broken. The region consists of two sub-ion or electron-scale layers, which contain intense electric fields. Formation of the two sub-layers is due to the complex electron flow pattern around the separatrix region. In the layer, E z is balanced by a combination of Hall term and the divergence of electron pressure tensor, with the Hall term being dominant. Our preliminary simulation result shows that the separatrix region in guide field reconnection also contains two sub-regions: the inner region and the outer region. However, the inner region contains only one current layer in contrast with the case without guide field.

  13. Fabrication and characterization of iron oxide dextran composite layers

    Science.gov (United States)

    Iconaru, S. L.; Predoi, S. A.; Beuran, M.; Ciobanu, C. S.; Trusca, R.; Ghita, R.; Negoi, I.; Teleanu, G.; Turculet, S. C.; Matei, M.; Badea, Monica; Prodan, A. M.

    2018-02-01

    Super paramagnetic iron oxide nanoparticles such as maghemite have been shown to exhibit antimicrobial properties [1-5]. Moreover, the iron oxide nanoparticles have been proposed as a potential magnetically controllable antimicrobial agent which could be directed to a specific infection [3-5]. The present research has focused on studies of the surface and structure of iron oxide dextran (D-IO) composite layers surface and structure. These composite layers were deposited on Si substrates. The structure of iron oxide dextran composite layers was investigated by X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) while the surface morphology was evaluated by Scanning Electron Microscopy (SEM). The structural characterizations of the iron oxide dextran composite layers revealed the basic constituents of both iron and dextran structure. Furthermore, the in vitro evaluation of the antifungal effect of the complex layers, which have been shown revealed to be active against C. albicans cells at distinct intervals of time, is exhibited. Our research came to confirm the fungicidal effect of iron oxide dextran composite layers. Also, our results suggest that iron oxide dextran surface may be used for medical treatment of biofilm associated Candida infections.

  14. Layer 2/3 synapses in monocular and binocular regions of tree shrew visual cortex express mAChR-dependent long-term depression and long-term potentiation.

    Science.gov (United States)

    McCoy, Portia; Norton, Thomas T; McMahon, Lori L

    2008-07-01

    Acetylcholine is an important modulator of synaptic efficacy and is required for learning and memory tasks involving the visual cortex. In rodent visual cortex, activation of muscarinic acetylcholine receptors (mAChRs) induces a persistent long-term depression (LTD) of transmission at synapses recorded in layer 2/3 of acute slices. Although the rodent studies expand our knowledge of how the cholinergic system modulates synaptic function underlying learning and memory, they are not easily extrapolated to more complex visual systems. Here we used tree shrews for their similarities to primates, including a visual cortex with separate, defined regions of monocular and binocular innervation, to determine whether mAChR activation induces long-term plasticity. We find that the cholinergic agonist carbachol (CCh) not only induces long-term plasticity, but the direction of the plasticity depends on the subregion. In the monocular region, CCh application induces LTD of the postsynaptic potential recorded in layer 2/3 that requires activation of m3 mAChRs and a signaling cascade that includes activation of extracellular signal-regulated kinase (ERK) 1/2. In contrast, layer 2/3 postsynaptic potentials recorded in the binocular region express long-term potentiation (LTP) following CCh application that requires activation of m1 mAChRs and phospholipase C. Our results show that activation of mAChRs induces long-term plasticity at excitatory synapses in tree shrew visual cortex. However, depending on the ocular inputs to that region, variation exists as to the direction of plasticity, as well as to the specific mAChR and signaling mechanisms that are required.

  15. Lateral and medial ventral occipitotemporal regions interact during the recognition of images revealed from noise

    Directory of Open Access Journals (Sweden)

    Barbara eNordhjem

    2016-01-01

    Full Text Available Several studies suggest different functional roles for the medial and the lateral ventral sections in object recognition. Texture and surface information is processed in medial regions, while shape information is processed in lateral sections. This begs the question whether and how these functionally specialized sections interact with each other and with early visual cortex to facilitate object recognition. In the current research, we set out to answer this question. In an fMRI study, thirteen subjects viewed and recognized images of objects and animals that were gradually revealed from noise while their brains were being scanned. We applied dynamic causal modeling (DCM – a method to characterize network interactions – to determine the modulatory effect of object recognition on a network comprising the primary visual cortex (V1, the lingual gyrus (LG in medial ventral cortex and the lateral occipital cortex (LO. We found that object recognition modulated the bilateral connectivity between LG and LO. Moreover, the feed-forward connectivity from V1 to LG and LO was modulated, while there was no evidence for feedback from these regions to V1 during object recognition. In particular, the interaction between medial and lateral areas supports a framework in which visual recognition of objects is achieved by networked regions that integrate information on image statistics, scene content and shape – rather than by a single categorically specialized region – within the ventral visual cortex.

  16. Impact of the Loess Plateau on the atmospheric boundary layer structure and air quality in the North China Plain: A case study

    International Nuclear Information System (INIS)

    Hu, Xiao-Ming; Ma, ZhiQiang; Lin, Weili; Zhang, Hongliang; Hu, Jianlin; Wang, Ying; Xu, Xiaobin; Fuentes, Jose D.; Xue, Ming

    2014-01-01

    The North China Plain (NCP), to the east of the Loess Plateau, experiences severe regional air pollution. During the daytime in the summer, the Loess Plateau acts as an elevated heat source. The impacts of such a thermal effect on meteorological phenomena (e.g., waves, precipitation) in this region have been discussed. However, its impacts on the atmospheric boundary layer structure and air quality have not been reported. It is hypothesized that the thermal effect of the Plateau likely modulates the boundary layer structure and ambient concentrations of pollutants over the NCP under certain meteorological conditions. Thus, this study investigates such effect and its impacts using measurements and three-dimensional model simulations. It is found that in the presence of daytime westerly wind in the lower troposphere (∼ 1 km above the NCP), warmer air above the Loess Plateau was transported over the NCP and imposed a thermal inversion above the mixed boundary layer, which acted as a lid and suppressed the mixed layer growth. As a result, pollutants accumulated in the shallow mixed layer and ozone was efficiently produced. The downward branch of the thermally-induced Mountain-Plains Solenoid circulation over the NCP contributed to enhancing the capping inversion and exacerbating air pollution. Previous studies have reported that low mixed layer, a factor for elevated pollution in the NCP, may be caused by aerosol scattering and absorption of solar radiation, frontal inversion, and large scale subsidence. The present study revealed a different mechanism (i.e., westerly warm advection) for the suppression of the mixed layer in summer NCP, which caused severe O 3 pollution. This study has important implications for understanding the essential meteorological factors for pollution episodes in this region and forecasting these severe events. - Highlights: • Low mixed layer exacerbates air pollution over the North China Plain (NCP) • Warm advection from the Loess

  17. Investigating a solar influence on cloud cover using the North American Regional Reanalysis data

    Directory of Open Access Journals (Sweden)

    Krahenbuhl Daniel Scott

    2015-01-01

    Full Text Available The controversial connection between cosmic rays, solar activity, and cloud cover is investigated using a climatological reconstructed reanalysis product: the North American Regional Reanalysis which provides high-resolution, low, mid-level, high, and total cloud cover data over a Lambert conformal conic projection permitting land/ocean discrimination. Pearson’s product-moment regional correlations were obtained between monthly cloud cover data and solar variability indicators, cosmic ray neutron monitors, several climatological indices, including the Atlantic Multidecadal Oscillation (AMO, and between cloud layers. Regions of the mid-latitude oceans exhibited a positive correlation with cosmic ray flux. Additionally, this maritime low cloud cover exhibits the only failed correlation significance with other altitudes. The cross correlation reveals that cloud cover is positively correlated everywhere but for ocean low cloud cover, supporting the unique response of the marine layer. The results of this investigation suggest that with the assumption that solar forcing does impact cloud cover, measurements of solar activity exhibits a slightly higher correlation than GCRs. The only instance where GCRs exhibit a positive regional correlation with cloud cover is for maritime low clouds. The AMO exerts the greatest control of cloud cover in the NARR domain.

  18. Crustal velocity structure of central Gansu Province from regional seismic waveform inversion using firework algorithm

    Science.gov (United States)

    Chen, Yanyang; Wang, Yanbin; Zhang, Yuansheng

    2017-04-01

    The firework algorithm (FWA) is a novel swarm intelligence-based method recently proposed for the optimization of multi-parameter, nonlinear functions. Numerical waveform inversion experiments using a synthetic model show that the FWA performs well in both solution quality and efficiency. We apply the FWA in this study to crustal velocity structure inversion using regional seismic waveform data of central Gansu on the northeastern margin of the Qinghai-Tibet plateau. Seismograms recorded from the moment magnitude ( M W) 5.4 Minxian earthquake enable obtaining an average crustal velocity model for this region. We initially carried out a series of FWA robustness tests in regional waveform inversion at the same earthquake and station positions across the study region, inverting two velocity structure models, with and without a low-velocity crustal layer; the accuracy of our average inversion results and their standard deviations reveal the advantages of the FWA for the inversion of regional seismic waveforms. We applied the FWA across our study area using three component waveform data recorded by nine broadband permanent seismic stations with epicentral distances ranging between 146 and 437 km. These inversion results show that the average thickness of the crust in this region is 46.75 km, while thicknesses of the sedimentary layer, and the upper, middle, and lower crust are 3.15, 15.69, 13.08, and 14.83 km, respectively. Results also show that the P-wave velocities of these layers and the upper mantle are 4.47, 6.07, 6.12, 6.87, and 8.18 km/s, respectively.

  19. Layer-by-Layer Self-Assembled Ferrite Multilayer Nanofilms for Microwave Absorption

    Directory of Open Access Journals (Sweden)

    Jiwoong Heo

    2015-01-01

    Full Text Available We demonstrate a simple method for fabricating multilayer thin films containing ferrite (Co0.5Zn0.5Fe2O4 nanoparticles, using layer-by-layer (LbL self-assembly. These films have microwave absorbing properties for possible radar absorbing and stealth applications. To demonstrate incorporation of inorganic ferrite nanoparticles into an electrostatic-interaction-based LbL self-assembly, we fabricated two types of films: (1 a blended three-component LbL film consisting of a sequential poly(acrylic acid/oleic acid-ferrite blend layer and a poly(allylamine hydrochloride layer and (2 a tetralayer LbL film consisting of sequential poly(diallyldimethylammonium chloride, poly(sodium-4-sulfonate, bPEI-ferrite, and poly(sodium-4-sulfonate layers. We compared surface morphologies, thicknesses, and packing density of the two types of ferrite multilayer film. Ferrite nanoparticles (Co0.5Zn0.5Fe2O4 were prepared via a coprecipitation method from an aqueous precursor solution. The structure and composition of the ferrite nanoparticles were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy, and scanning electron microscopy. X-ray diffraction patterns of ferrite nanoparticles indicated a cubic spinel structure, and energy dispersive X-ray spectroscopy revealed their composition. Thickness growth and surface morphology were measured using a profilometer, atomic force microscope, and scanning electron microscope.

  20. Hemodynamic monitoring in different cortical layers with a single fiber optical system

    Science.gov (United States)

    Yu, Linhui; Noor, M. Sohail; Kiss, Zelma H. T.; Murari, Kartikeya

    2018-02-01

    Functional monitoring of highly-localized deep brain structures is of great interest. However, due to light scattering, optical methods have limited depth penetration or can only measure from a large volume. In this research, we demonstrate continuous measurement of hemodynamics in different cortical layers in response to thalamic deep brain stimulation (DBS) using a single fiber optical system. A 200-μm-core-diameter multimode fiber is used to deliver and collect light from tissue. The fiber probe can be stereotaxically implanted into the brain region of interest at any depth to measure the di use reflectance spectra from a tissue volume of 0.02-0.03 mm3 near the fiber tip. Oxygenation is then extracted from the reflectance spectra using an algorithm based on Monte Carlo simulations. Measurements were performed on the surface (cortical layer I) and at 1.5 mm depth (cortical layer VI) of the motor cortex in anesthetized rats with thalamic DBS. Preliminary results revealed the oxygenation changes in response to DBS. Moreover, the baseline as well as the stimulus-evoked change in oxygenation were different at the two depths of cortex.

  1. Ft-Ir Spectroscopic Analysis of Potsherds Excavated from the First Settlement Layer of Kuriki Mound, Turkey

    Science.gov (United States)

    Bayazit, Murat; Isik, Iskender; Cereci, Sedat; Issi, Ali; Genc, Elif

    The region covering Southeastern Anatolia takes place in upper Mesopotamia, so it has numerous cultural heritages due to its witness to various social movements of different civilizations in ancient times. Kuruki Mound is located on the junction point of Tigris River and Batman Creek, near Oymatas village which is almost 15 km to Batman, Turkey. The mound is dated back to Late Chalcolithic. Archaeological excavations are carried out on two hills named as “Kuriki Mound-1” and “Kuriki Mound-2” in which 4-layer and 2-layer settlements have been revealed, respectively. This region will be left under the water by the reservoir lake of Ilısu Dam when its construction is completed. Thus, characterization of ancient materials such as potsherds, metals and skeleton ruins should be rapidly done. In this study, 12 potsherds excavated from Layer-1 (the first settlement layer after the surface) in Kuriki Mound-2 were investigated by FT-IR spectrometry. Energy dispersive X-ray fluorescence (EDXRF) and X-ray diffraction (XRD) analyses were used as complementary techniques in order to expose chemical and mineralogical/phase contents, respectively. Obtained results showed that the potteries have been produced with calcareous clays and they include moderate amounts of MgO, K2O, Na2O and Fe2O3 in this context. Additionally, high temperature phases have also been detected with XRD analyses in some samples.

  2. Flexible 2D layered material junctions

    Science.gov (United States)

    Balabai, R.; Solomenko, A.

    2018-03-01

    Within the framework of the methods of the electron density functional and the ab initio pseudopotential, we have obtained the valence electron density spatial distribution, the densities of electron states, the widths of band gaps, the charges on combined regions, and the Coulomb potentials for graphene-based flexible 2D layered junctions, using author program complex. It is determined that the bending of the 2D layered junctions on the angle α leads to changes in the electronic properties of these junctions. In the graphene/graphane junction, there is clear charge redistribution with different signs in the regions of junctions. The presence in the heterojunctions of charge regions with different signs leads to the formation of potential barriers. The greatest potential jump is in the graphene/fluorographene junction. The greatest value of the band gap width is in the graphene/graphane junction.

  3. Cloaks with multiple invisible regions

    International Nuclear Information System (INIS)

    Luo, Yang; Zhu, Shouzheng; He, Lianxing; Wang, Yu

    2011-01-01

    This paper proposes a general method of extending the effective invisible regions for both the shell-like interior cloak and the complementary media exterior cloak, without affecting their original cloaking regions. The proposed method is based on layered spatial mapping instead of the intact mapping. Certain interior or exterior invisible regions can be obtained by properly using a compressed or folded transformation in each space layer. Therefore, the proposal enables the as-designed cloaks to provide multiple invisible regions of different types simultaneously. Thus objects can be hidden in the interior cavity and/or in the exterior space, or even be embedded between the cloaking shells

  4. Effects of magnetic storm phases on F layer irregularities below the auroral oval

    International Nuclear Information System (INIS)

    Aarons, J.; Gurgiolo, C.; Rodger, A.S.

    1988-01-01

    Observations of F-layer irregularity development and intensity were obtained between September and October 1981, primarily over subauroral latitudes in the area of the plasmapause. The results reveal the descent of the auroral irregularity region to include subauroral latitudes in the general area of the plasmapause during the main phases of a series of magnetic storms. Irregularities were found primarily at lower latitudes during the subauroral or plasmapause storm. A model for the subauroral irregularities in recovery phases of magnetic storms is proposed in which energy stored in the ring current is slowly released. 27 references

  5. New global electron density observations from GPS-RO in the D- and E-Region ionosphere

    Science.gov (United States)

    Wu, Dong L.

    2018-06-01

    A novel retrieval technique is developed for electron density (Ne) in the D- and E-region (80-120 km) using the high-quality 50-Hz GPS radio occultation (GPS-RO) phase measurements. The new algorithm assumes a slow, linear variation in the F-region background when the GPS-RO passes through the D- and E-region, and extracts the Ne profiles at 80-130 km from the phase advance signal caused by Ne. Unlike the conventional Abel function, the new approach produces a sharp Ne weighting function in the lower ionosphere, and the Ne retrievals are in good agreement with the IRI (International Reference Ionosphere) model in terms of monthly maps, zonal means and diurnal variations. The daytime GPS-RO Ne profiles can be well characterized by the α-Chapman function of three parameters (NmE, hmE and H), showing that the bottom of E-region is deepening and sharpening towards the summer pole. At high latitudes the monthly GPS-RO Ne maps at 80-120 km reveal clear enhancement in the auroral zones, more prominent at night, as a result of energetic electron precipitation (EEP) from the outer radiation belt. The D-/E-region auroral Ne is strongly correlated with Kp on a daily basis. The new Ne data allow further comprehensive analyses of the sporadic E (Es) phenomena in connection with the background Ne in the E-region. The layered (2-10 km) and fluctuated (Layer than Ne_Pert, are extracted with respect to the background Ne_Region on a profile-by-profile basis. The Ne_Layer component has a strong but highly-refined peak at ∼105 km, with an amplitude smaller than Ne_Region approximately by an order of magnitude. The Ne_Pert component, which was studied extensively in the past, is ∼2 orders of magnitude weaker than Ne_Layer. Both Ne_Layer and Ne_Pert are subject to significant diurnal and semidiurnal variations, showing downward progression with local time in amplitude. The 11-year solar cycle dominates the Ne interannual variations, showing larger Ne_Region and Ne_Layer but smaller

  6. A laser syringe aimed at delivering drug into the outer layer of human skin

    Science.gov (United States)

    Yoh, Jack J.; Jang, Hun-jae; Park, Mi-ae; Han, Tae-hee; Hah, Jung-moo

    2012-07-01

    A desire to eliminate hypodermic needle in transdermal drug delivery may now be realized. Imaging of the skin after injection of fluorescent probe and biotin via the bio-ballistic technique revealed the epidermal and dermal layers which were stained well below 60 μm underneath the abdominal skin of the guinea-pig. An extensive network of cells are shown in the deeper layer of the stained dermis as the distributed fluorescein isothiocyanate (FITC) dose is administered by repeated injection via the laser-based microjet. Here, we show our method of laser-based microjet drug delivery is capable of breaching guinea-pig's skin tissue and then delivering controlled dose of drug to the targeted region between 10 to 400 μm underneath the outermost layer of the skin. While minimizing pain and tissue damage by reducing the injection volume to ˜100 nl per pulse and the microjet diameter of half the conventional syringe needle in 100 μm, the optimally controlled delivery of liquid drug by the irradiated laser pulse is shown possible.

  7. Impact of the Loess Plateau on the atmospheric boundary layer structure and air quality in the North China Plain: a case study.

    Science.gov (United States)

    Hu, Xiao-Ming; Ma, ZhiQiang; Lin, Weili; Zhang, Hongliang; Hu, Jianlin; Wang, Ying; Xu, Xiaobin; Fuentes, Jose D; Xue, Ming

    2014-11-15

    The North China Plain (NCP), to the east of the Loess Plateau, experiences severe regional air pollution. During the daytime in the summer, the Loess Plateau acts as an elevated heat source. The impacts of such a thermal effect on meteorological phenomena (e.g., waves, precipitation) in this region have been discussed. However, its impacts on the atmospheric boundary layer structure and air quality have not been reported. It is hypothesized that the thermal effect of the Plateau likely modulates the boundary layer structure and ambient concentrations of pollutants over the NCP under certain meteorological conditions. Thus, this study investigates such effect and its impacts using measurements and three-dimensional model simulations. It is found that in the presence of daytime westerly wind in the lower troposphere (~1 km above the NCP), warmer air above the Loess Plateau was transported over the NCP and imposed a thermal inversion above the mixed boundary layer, which acted as a lid and suppressed the mixed layer growth. As a result, pollutants accumulated in the shallow mixed layer and ozone was efficiently produced. The downward branch of the thermally-induced Mountain-Plains Solenoid circulation over the NCP contributed to enhancing the capping inversion and exacerbating air pollution. Previous studies have reported that low mixed layer, a factor for elevated pollution in the NCP, may be caused by aerosol scattering and absorption of solar radiation, frontal inversion, and large scale subsidence. The present study revealed a different mechanism (i.e., westerly warm advection) for the suppression of the mixed layer in summer NCP, which caused severe O3 pollution. This study has important implications for understanding the essential meteorological factors for pollution episodes in this region and forecasting these severe events. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. JUPITER AS AN EXOPLANET: UV TO NIR TRANSMISSION SPECTRUM REVEALS HAZES, A Na LAYER, AND POSSIBLY STRATOSPHERIC H{sub 2}O-ICE CLOUDS

    Energy Technology Data Exchange (ETDEWEB)

    Montañés-Rodríguez, Pilar; González-Merino, B.; Pallé, E. [Instituto de Astrofísica de Canarias, C/Vía Láctea s/n, E-38200 La Laguna (Spain); López-Puertas, Manuel [Departamento de Astrofísica, Universidad de La Laguna, Av., Astrofísico Francisco Sánchez, s/n, E-38206 La Laguna (Spain); García-Melendo, E., E-mail: pmr@iac.es [Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía s/n, E-18080 Granada (Spain)

    2015-03-01

    Currently, the analysis of transmission spectra is the most successful technique to probe the chemical composition of exoplanet atmospheres. However, the accuracy of these measurements is constrained by observational limitations and the diversity of possible atmospheric compositions. Here, we show the UV–VIS–IR transmission spectrum of Jupiter as if it were a transiting exoplanet, obtained by observing one of its satellites, Ganymede, while passing through Jupiter’s shadow, i.e., during a solar eclipse from Ganymede. The spectrum shows strong extinction due to the presence of clouds (aerosols) and haze in the atmosphere and strong absorption features from CH{sub 4}. More interestingly, the comparison with radiative transfer models reveals a spectral signature, which we attribute here to a Jupiter stratospheric layer of crystalline H{sub 2}O ice. The atomic transitions of Na are also present. These results are relevant for the modeling and interpretation of giant transiting exoplanets. They also open a new technique to explore the atmospheric composition of the upper layers of Jupiter’s atmosphere.

  9. Molecular cloning and construction of the coding region for human acetylcholinesterase reveals a G + C-rich attenuating structure

    International Nuclear Information System (INIS)

    Soreq, H.; Ben-Aziz, R.; Prody, C.A.; Seidman, S.; Gnatt, A.; Neville, L.; Lieman-Hurwitz, J.; Lev-Lehman, E.; Ginzberg, D.; Lapidot-Lifson, Y.; Zakut, H.

    1990-01-01

    To study the primary structure of human acetylcholinesterase and its gene expression and amplification, cDNA libraries from human tissues expressing oocyte-translatable AcChoEase mRNA were constructed and screened with labeled oligodeoxynucleotide probes. Several cDNA clones were isolated that encoded a polypeptide with ≥50% identically aligned amino acids to Torpedo AcChoEase and human butyrylcholinesterase. However, these cDNA clones were all truncated within a 300-nucleotide-long G + C-rich region with a predicted pattern of secondary structure having a high Gibbs free energy downstream from the expected 5' end of the coding region. Screening of a genomic DNA library revealed the missing 5' domain. When ligated to the cDNA and constructed into a transcription vector, this sequence encoded a synthetic mRNA translated in microinjected oocytes into catalytically active AcChoEase with marked preference for acetylthiocholine over butyrylthiocholine as a substrate, susceptibility to inhibition by the AcChoEase inhibitor BW284C51, and resistance to the AcChoEase inhibitor tetraisopropylpyrophosphoramide. Blot hybridization of genomic DNA from different individuals carrying amplified AcChoEase genes revealed variable intensities and restriction patterns with probes from the regions upstream and downstream from the predicted G + C-rich structure. Thus, the human AcChoEase gene includes a putative G + C-rich attenuator domain and is subject to structural alterations in cases of AcChoEase gene amplification

  10. New data for natural situation of Prebaikal region in holocene

    International Nuclear Information System (INIS)

    Kuz'min, S.B.; Dan'ko, L.V.; Snytko, V.A.; Bezrukova, E.V.; Orlova, L.A.

    2007-01-01

    On the basis of the radiocarbon dating data one performed a comprehensive study of the paragenetic series of loose deposits of the layers located in the Baikal Lake western coast central part. The main changes of the natural situations of the Baikal Lake region in the holocene were revealed to take place in the early Subatlantic period (2290+-90 14 C years ago), in the latter half of the Medieval optimum (1410 - 1040+-60 14 C years ago) and in the Cryogenic period (885+-30 - 365+-30 14 C years ago) [ru

  11. Layer-by-layer assembly of patchy particles as a route to nontrivial structures

    Science.gov (United States)

    Patra, Niladri; Tkachenko, Alexei V.

    2017-08-01

    We propose a strategy for robust high-quality self-assembly of nontrivial periodic structures out of patchy particles and investigate it with Brownian dynamics simulations. Its first element is the use of specific patch-patch and shell-shell interactions between the particles, which can be implemented through differential functionalization of patched and shell regions with specific DNA strands. The other key element of our approach is the use of a layer-by-layer protocol that allows one to avoid the formation of undesired random aggregates. As an example, we design and self-assemble in silico a version of a double diamond lattice in which four particle types are arranged into bcc crystal made of four fcc sublattices. The lattice can be further converted to cubic diamond by selective removal of the particles of certain types. Our results demonstrate that by combining the directionality, selectivity of interactions, and the layer-by-layer protocol, a high-quality robust self-assembly can be achieved.

  12. Nonlinear electron acoustic structures generated on the high-potential side of a double layer

    Directory of Open Access Journals (Sweden)

    R. Pottelette

    2009-04-01

    Full Text Available High-time resolution measurements of the electron distribution function performed in the auroral upward current region reveals a large asymmetry between the low- and high-potential sides of a double-layer. The latter side is characterized by a large enhancement of a locally trapped electron population which corresponds to a significant part (~up to 30% of the total electron density. As compared to the background hot electron population, this trapped component has a very cold temperature in the direction parallel to the static magnetic field. Accordingly, the differential drift between the trapped and background hot electron populations generates high frequency electron acoustic waves in a direction quasi-parallel to the magnetic field. The density of the trapped electron population can be deduced from the frequency where the electron acoustic spectrum maximizes. In the auroral midcavity region, the electron acoustic waves may be modulated by an additional turbulence generated in the ion acoustic range thanks to the presence of a pre-accelerated ion beam located on the high-potential side of the double layer. Electron holes characterized by bipolar pulses in the electric field are sometimes detected in correlation with these electron acoustic wave packets.

  13. Tomographic Structural Changes of Retinal Layers after Internal Limiting Membrane Peeling for Macular Hole Surgery.

    Science.gov (United States)

    Faria, Mun Yueh; Ferreira, Nuno P; Cristóvao, Diana M; Mano, Sofia; Sousa, David Cordeiro; Monteiro-Grillo, Manuel

    2018-01-01

    To highlight tomographic structural changes of retinal layers after internal limiting membrane (ILM) peeling in macular hole surgery. Nonrandomized prospective, interventional study in 38 eyes (34 patients) subjected to pars plana vitrectomy and ILM peeling for idiopathic macular hole. Retinal layers were assessed in nasal and temporal regions before and 6 months after surgery using spectral domain optical coherence tomography. Total retinal thickness increased in the nasal region and decreased in the temporal region. The retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), and inner plexiform layer (IPL) showed thinning on both nasal and temporal sides of the fovea. The thickness of the outer plexiform layer (OPL) increased. The outer nuclear layer (ONL) and outer retinal layers (ORL) increased in thickness after surgery in both nasal and temporal regions. ILM peeling is associated with important alterations in the inner retinal layer architecture, with thinning of the RNFL-GCL-IPL complex and thickening of OPL, ONL, and ORL. These structural alterations can help explain functional outcome and could give indications regarding the extent of ILM peeling, even though peeling seems important for higher rate of hole closure. © 2017 S. Karger AG, Basel.

  14. Peeling Back the Layers

    Science.gov (United States)

    2004-01-01

    NASA's Mars Exploration Rover Spirit took this panoramic camera image of the rock target named 'Mazatzal' on sol 77 (March 22, 2004). It is a close-up look at the rock face and the targets that will be brushed and ground by the rock abrasion tool in upcoming sols. Mazatzal, like most rocks on Earth and Mars, has layers of material near its surface that provide clues about the history of the rock. Scientists believe that the top layer of Mazatzal is actually a coating of dust and possibly even salts. Under this light coating may be a more solid portion of the rock that has been chemically altered by weathering. Past this layer is the unaltered rock, which may give scientists the best information about how Mazatzal was formed. Because each layer reveals information about the formation and subsequent history of Mazatzal, it is important that scientists get a look at each of them. For this reason, they have developed a multi-part strategy to use the rock abrasion tool to systematically peel back Mazatzal's layers and analyze what's underneath with the rover's microscopic imager, and its Moessbauer and alpha particle X-ray spectrometers. The strategy began on sol 77 when scientists used the microscopic imager to get a closer look at targets on Mazatzal named 'New York,' 'Illinois' and 'Arizona.' These rock areas were targeted because they posed the best opportunity for successfully using the rock abrasion tool; Arizona also allowed for a close-up look at a range of tones. On sol 78, Spirit's rock abrasion tool will do a light brushing on the Illinois target to preserve some of the surface layers. Then, a brushing of the New York target should remove the top coating of any dust and salts and perhaps reveal the chemically altered rock underneath. Finally, on sol 79, the rock abrasion tool will be commanded to grind into the New York target, which will give scientists the best chance of observing Mazatzal's interior. The Mazatzal targets were named after the home states of

  15. Layered tin dioxide microrods

    International Nuclear Information System (INIS)

    Duan Junhong; Huang Hongbo; Gong Jiangfeng; Zhao Xiaoning; Cheng Guangxu; Yang Shaoguang

    2007-01-01

    Single-crystalline layered SnO 2 microrods were synthesized by a simple tin-water reaction at 900 deg. C. The structural and optical properties of the sample were characterized by x-ray powder diffraction, energy-dispersive x-ray spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy, Raman scattering and photoluminescence (PL) spectroscopy. High resolution transmission electron microscopy studies and selected area electron diffraction patterns revealed that the layered SnO 2 microrods are single crystalline and their growth direction is along [1 1 0]. The growth mechanism of the microrods was proposed based on SEM, TEM characterization and thermodynamic analysis. It is deduced that the layered microrods grow by the stacking of SnO 2 sheets with a (1 1 0) surface in a vapour-liquid-solid process. Three emission peaks at 523, 569 and 626 nm were detected in room-temperature PL measurements

  16. Transitional and turbulent flat-plate boundary layers with heat transfer

    Science.gov (United States)

    Wu, Xiaohua; Moin, Parviz

    2010-11-01

    We report on our direct numerical simulation of two incompressible, nominally zero-pressure-gradient flat-plate boundary layers from momentum thickness Reynolds number 80 to 1950. Heat transfer between the constant-temperature solid surface and the free-stream is also simulated with molecular Prandtl number=1. Throughout the entire flat-plate, the ratio of Stanton number and skin-friction St/Cfdeviates from the exact Reynolds analogy value of 0.5 by less than 1.5%. Turbulent Prandtl number t peaks at the wall. Preponderance of hairpin vortices is observed in both the transitional and turbulent regions of the boundary layers. In particular, the internal structure of merged turbulent spots is hairpin forest; the internal structure of infant turbulent spots is hairpin packet. Numerous hairpin vortices are readily detected in both the near-wall and outer regions of the boundary layers up to momentum thickness Reynolds number 1950. This suggests that the hairpin vortices in the turbulent region are not simply the aged hairpin forests convected from the upstream transitional region. Temperature iso-surfaces in the companion thermal boundary layers are found to be a useful tracer in identifying hairpin vortex structures.

  17. Tokamak plasma boundary layer model

    International Nuclear Information System (INIS)

    Volkov, T.F.; Kirillov, V.D.

    1983-01-01

    A model has been developed for the limiter layer and for the boundary region of the plasma column in a tokamak to facilitate analytic calculations of the thickness of the limiter layers, the profiles and boundary values of the temperature and the density under various conditions, and the difference between the electron and ion temperatures. This model can also be used to analyze the recycling of neutrals, the energy and particle losses to the wall and the limiter, and other characteristics

  18. Ion-acoustic solitary waves near double layers

    International Nuclear Information System (INIS)

    Kuehl, H.H.; Imen, K.

    1985-01-01

    The possibility of ion-acoustic solitary-wave solutions in the uniform plasma on the high-potential side of double layer is investigated. Based on a fluid model of the double layer, it is found that both compressive and rarefactive solitary waves are allowed. Curves are presented which show the regions in parameter space in which these solutions exist

  19. Magnetic structure of Tb-Fe films with an artificially layered structure

    International Nuclear Information System (INIS)

    Yamauchi, K.; Habu, K.; Sato, N.

    1988-01-01

    The magnetic structure of Tb-Fe films with an artificially layered structure has been investigated by measuring the temperature dependence of the magnetization of the films. Ferrimagnetic coupling between Tb and Fe through the interface was explicitly observed up to about 9-A Tb and 10-A Fe layers. Films with thinner Tb and Fe layers than these thicknesses are composed of only ferrimagnetically coupled Tb-Fe regions. Films with thicker layers of Tb and Fe are composed of ferrimagnetically coupled Tb-Fe, ferromagnetic Fe, ferromagnetic Tb, and/or magnetically compensated Tb regions. The Tb-Fe films exhibit various temperature dependencies of the magnetization corresponding to these magnetic structures

  20. Thermal regime of the lithosphere and prediction of seismic hazard in the Caspian region

    International Nuclear Information System (INIS)

    Levin, L.E.; Solodilov, L.N.; Kondorskaya, N.V.; Gasanov, A.G; Panahi, B.M.

    2002-01-01

    Full text : Prediction of seicmicity is one of elements of ecology hazard warning. In this collective research, it is elaborated in three directions : quantitative estimate of regional faults by level of seismic activity; ascertainment of space position of earthquake risk zones, determination of high seismic potential sites for the period of the next 3-5 years. During elaboration of prediction, it takes into account that peculiar feature all over the is determined by relationship of about 90 percent of earthquake hypocenters and released energy of seismic waves with elactic-brittle ayer of the lithosphere. Concetration of earthquakes epicenters is established predominantly in zones of complex structure of elastic-brittle layer where gradient of it thickness is 20-30 km. Directions of hypocenters migration in the plastic-viscous layer reveal a space position of seismic dangerous zones. All this provides a necessity for generalization of data on location of earthquakes epicenters; determination of their magnitudes, space position of regional faults and heat flow with calculation of thermal regime being made for clarification of the lithosphere and elastic-brittle thickness variations separately. General analysis includes a calculation of released seismic wave energy and determination of peculiar features of its distribution in the entire region and also studies of hypocenters migration in the plastic-viscous layer of the litosphere in time.

  1. Shear wave propagation in piezoelectric-piezoelectric composite layered structure

    Directory of Open Access Journals (Sweden)

    Anshu Mli Gaur

    Full Text Available The propagation behavior of shear wave in piezoelectric composite structure is investigated by two layer model presented in this approach. The composite structure comprises of piezoelectric layers of two different materials bonded alternatively. Dispersion equations are derived for propagation along the direction normal to the layering and in direction of layering. It has been revealed that thickness and elastic constants have significant influence on propagation behavior of shear wave. The phase velocity and wave number is numerically calculated for alternative layer of Polyvinylidene Difluoride (PVDF and Lead Zirconate Titanate (PZT-5H in composite layered structure. The analysis carried out in this paper evaluates the effect of volume fraction on the phase velocity of shear wave.

  2. Structure of the oceanic mixed layer in western Bay of Bengal during MONEX

    Digital Repository Service at National Institute of Oceanography (India)

    Anto, A.F.; Somayajulu, Y.K.

    layer conditions of the overlying atmosphere. Structure of OML, as delineated with respect to the diurnal variation of temperature with depth, revealed three sub-layers: wave mixed, diurnal thermocline and transition layer. The first two sub...

  3. Hiding the interior region of core-shell nanoparticles with quantum invisible cloaks

    Science.gov (United States)

    Lee, Jeng Yi; Lee, Ray-Kuang

    2014-04-01

    Based on the scattering cancellation, we provide a method not only making a nanoparticle nearly invisible, but also hiding its interior region from the outside probing matter wave. By applying the interplay among the nodal points of partial waves along with the concept of streamline in fluid dynamics for probability flux, a quantum invisible cloak to the electron transport in a host semiconductor is demonstrated by simultaneously guiding the probability flux outside a hidden region and keeping the total scattering cross section negligible. As the probability flux vanishes in the interior region, one can embed any materials inside a multiple core-shell nanoparticle without affecting physical observables from the outside. Our results reveal the possibility to design a protection shield layer for fragile interior parts from the impact of transport electrons.

  4. Near-wake flow structure downwind of a wind turbine in a turbulent boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei; Markfort, Corey D. [University of Minnesota, Saint Anthony Falls Laboratory, Department of Civil Engineering, Minneapolis, MN (United States); Porte-Agel, Fernando [Ecole Polytechnique Federale de Lausanne (EPFL), ENAC-IIE-WIRE, Wind Engineering and Renewable Energy Laboratory (WIRE), Lausanne (Switzerland)

    2012-05-15

    Wind turbines operate in the surface layer of the atmospheric boundary layer, where they are subjected to strong wind shear and relatively high turbulence levels. These incoming boundary layer flow characteristics are expected to affect the structure of wind turbine wakes. The near-wake region is characterized by a complex coupled vortex system (including helicoidal tip vortices), unsteadiness and strong turbulence heterogeneity. Limited information about the spatial distribution of turbulence in the near wake, the vortex behavior and their influence on the downwind development of the far wake hinders our capability to predict wind turbine power production and fatigue loads in wind farms. This calls for a better understanding of the spatial distribution of the 3D flow and coherent turbulence structures in the near wake. Systematic wind-tunnel experiments were designed and carried out to characterize the structure of the near-wake flow downwind of a model wind turbine placed in a neutral boundary layer flow. A horizontal-axis, three-blade wind turbine model, with a rotor diameter of 13 cm and the hub height at 10.5 cm, occupied the lowest one-third of the boundary layer. High-resolution particle image velocimetry (PIV) was used to measure velocities in multiple vertical stream-wise planes (x-z) and vertical span-wise planes (y-z). In particular, we identified localized regions of strong vorticity and swirling strength, which are the signature of helicoidal tip vortices. These vortices are most pronounced at the top-tip level and persist up to a distance of two to three rotor diameters downwind. The measurements also reveal strong flow rotation and a highly non-axisymmetric distribution of the mean flow and turbulence structure in the near wake. The results provide new insight into the physical mechanisms that govern the development of the near wake of a wind turbine immersed in a neutral boundary layer. They also serve as important data for the development and

  5. Turbulent entrainment across turbulent-nonturbulent interfaces in stably stratified mixing layers

    Science.gov (United States)

    Watanabe, T.; Riley, J. J.; Nagata, K.

    2017-10-01

    The entrainment process in stably stratified mixing layers is studied in relation to the turbulent-nonturbulent interface (TNTI) using direct numerical simulations. The statistics are calculated with the interface coordinate in an Eulerian frame as well as with the Lagrangian fluid particles entrained from the nonturbulent to the turbulent regions. The characteristics of entrainment change as the buoyancy Reynolds number Reb decreases and the flow begins to layer. The baroclinic torque delays the enstrophy growth of the entrained fluids at small Reb, while this effect is less efficient for large Reb. The entrained particle movement within the TNTI layer is dominated by the small dissipative scales, and the rapid decay of the kinetic energy dissipation rate due to buoyancy causes the entrained particle movement relative to the interface location to become slower. Although the Eulerian statistics confirm that there exists turbulent fluid with strong vorticity or with large buoyancy frequency near the TNTI, the entrained fluid particles circumvent these regions by passing through the TNTI in strain-dominant regions or in regions with small buoyancy frequency. The multiparticle statistics show that once the nonturbulent fluid volumes are entrained, they are deformed into flattened shapes in the vertical direction and diffuse in the horizontal direction. When Reb is large enough for small-scale turbulence to exist, the entrained fluid is able to penetrate into the turbulent core region. Once the flow begins to layer with decreasing Reb, however, the entrained fluid volume remains near the outer edge of the turbulent region and forms a stably stratified layer without vertical overturning.

  6. Counting molecular-beam grown graphene layers

    Energy Technology Data Exchange (ETDEWEB)

    Plaut, Annette S. [School of Physics, University of Exeter, Exeter EX4 4QL (United Kingdom); Wurstbauer, Ulrich [Department of Physics, Columbia University, New York, New York 10027 (United States); Pinczuk, Aron [Department of Physics, Columbia University, New York, New York 10027 (United States); Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States); Garcia, Jorge M. [MBE Lab, IMM-Instituto de Microelectronica de Madrid (CNM-CSIC), Madrid, E-28760 (Spain); Pfeiffer, Loren N. [Electrical Engineering Department, Princeton University, New Jersey 08544 (United States)

    2013-06-17

    We have used the ratio of the integrated intensity of graphene's Raman G peak to that of the silicon substrate's first-order optical phonon peak, accurately to determine the number of graphene layers across our molecular-beam (MB) grown graphene films. We find that these results agree well both, with those from our own exfoliated single and few-layer graphene flakes, and with the results of Koh et al.[ACS Nano 5, 269 (2011)]. We hence distinguish regions of single-, bi-, tri-, four-layer, etc., graphene, consecutively, as we scan coarsely across our MB-grown graphene. This is the first, but crucial, step to being able to grow, by such molecular-beam-techniques, a specified number of large-area graphene layers, to order.

  7. Optical losses in p-type layers of GaN ridge waveguides in the IR region

    Science.gov (United States)

    Westreich, Ohad; Katz, Moti; Atar, Gil; Paltiel, Yossi; Sicron, Noam

    2017-07-01

    Optical losses in c-plane (0001) GaN ridge waveguides, containing Mg-doped layers, were measured at 1064 nm, using the Fabry-Perot method. The losses increase linearly with the modal content of the p-layer, indicating that the absorption in these waveguides is dominated by p-layer absorption. The p-layer absorption is strongly anisotropic with E⊥c losses 4 times higher than E∥c. The absorption is temperature independent between 10 °C and 60 °C, supporting the possibility that it is related to Mg-bound holes.

  8. Binary Oxide p-n Heterojunction Piezoelectric Nanogenerators with an Electrochemically Deposited High p-Type Cu2O Layer.

    Science.gov (United States)

    Baek, Seung Ki; Kwak, Sung Soo; Kim, Joo Sung; Kim, Sang Woo; Cho, Hyung Koun

    2016-08-31

    The high performance of ZnO-based piezoelectric nanogenerators (NGs) has been limited due to the potential screening from intrinsic electron carriers in ZnO. We have demonstrated a novel approach to greatly improve piezoelectric power generation by electrodepositing a high-quality p-type Cu2O layer between the piezoelectric semiconducting film and the metal electrode. The p-n heterojunction using only oxides suppresses the screening effect by forming an intrinsic depletion region, and thus sufficiently enhances the piezoelectric potential, compared to the pristine ZnO piezoelectric NG. Interestingly, a Sb-doped Cu2O layer has high mobility and low surface trap states. Thus, this doped layer is an attractive p-type material to significantly improve piezoelectric performance. Our results revealed that p-n junction NGs consisting of Au/ZnO/Cu2O/indium tin oxide with a Cu2O:Sb (cuprous oxide with a small amount of antimony) layer of sufficient thickness (3 μm) exhibit an extraordinarily high piezoelectric potential of 0.9 V and a maximum output current density of 3.1 μA/cm(2).

  9. Common brain regions underlying different arithmetic operations as revealed by conjunct fMRI-BOLD activation.

    Science.gov (United States)

    Fehr, Thorsten; Code, Chris; Herrmann, Manfred

    2007-10-03

    The issue of how and where arithmetic operations are represented in the brain has been addressed in numerous studies. Lesion studies suggest that a network of different brain areas are involved in mental calculation. Neuroimaging studies have reported inferior parietal and lateral frontal activations during mental arithmetic using tasks of different complexities and using different operators (addition, subtraction, etc.). Indeed, it has been difficult to compare brain activation across studies because of the variety of different operators and different presentation modalities used. The present experiment examined fMRI-BOLD activity in participants during calculation tasks entailing different arithmetic operations -- addition, subtraction, multiplication and division -- of different complexities. Functional imaging data revealed a common activation pattern comprising right precuneus, left and right middle and superior frontal regions during all arithmetic operations. All other regional activations were operation specific and distributed in prominently frontal, parietal and central regions when contrasting complex and simple calculation tasks. The present results largely confirm former studies suggesting that activation patterns due to mental arithmetic appear to reflect a basic anatomical substrate of working memory, numerical knowledge and processing based on finger counting, and derived from a network originally related to finger movement. We emphasize that in mental arithmetic research different arithmetic operations should always be examined and discussed independently of each other in order to avoid invalid generalizations on arithmetics and involved brain areas.

  10. Three Dimensional Plenoptic PIV Measurements of a Turbulent Boundary Layer Overlying a Hemispherical Roughness Element

    Science.gov (United States)

    Johnson, Kyle; Thurow, Brian; Kim, Taehoon; Blois, Gianluca; Christensen, Kenneth

    2016-11-01

    Three-dimensional, three-component (3D-3C) measurements were made using a plenoptic camera on the flow around a roughness element immersed in a turbulent boundary layer. A refractive index matched approach allowed whole-field optical access from a single camera to a measurement volume that includes transparent solid geometries. In particular, this experiment measures the flow over a single hemispherical roughness element made of acrylic and immersed in a working fluid consisting of Sodium Iodide solution. Our results demonstrate that plenoptic particle image velocimetry (PIV) is a viable technique to obtaining statistically-significant volumetric velocity measurements even in a complex separated flow. The boundary layer to roughness height-ratio of the flow was 4.97 and the Reynolds number (based on roughness height) was 4.57×103. Our measurements reveal key flow features such as spiraling legs of the shear layer, a recirculation region, and shed arch vortices. Proper orthogonal decomposition (POD) analysis was applied to the instantaneous velocity and vorticity data to extract these features. Supported by the National Science Foundation Grant No. 1235726.

  11. On the recent warming in the subcloud layer entropy and vertically integrated moist static energy over South Asian Monsoon region.

    Science.gov (United States)

    Konduru, R.; Gupta, A.; Matsumoto, J.; Takahashi, H. G.

    2017-12-01

    In order to explain monsoon circulation, surface temperature gradients described as most traditional concept. However, it cannot explain certain important aspects of monsoon circulation. Later, convective quasi-equilibrium framework and vertically integrated atmospheric energy budget has become recognized theories to explain the monsoon circulation. In this article, same theories were analyzed and observed for the duration 1979-2010 over south Asian summer monsoon region. With the help of NCEP-R2, NOAA 20th Century, and Era-Interim reanalysis an important feature was noticed pertained to subcloud layer entropy and vertical moist static energy. In the last 32 years, subcloud layer entropy and vertically integrated moist static energy has shown significant seasonal warming all over the region with peak over the poleward flank of the cross-equatorial cell. The important reason related to the warming was found to be increase in surface enthalpy fluxes. Instead, other dynamical contributions pertained to the warming was also observed. Increase in positive anomalies of vertical advection of moist static energy over northern Bay of Bengal, Central India, Peninsular India, Eastern Arabian Sea, and Equatorial Indian Ocean was found to be an important dynamic factor contributing for warming of vertically integrated moist static energy. Along with it vertical moist stability has also supported the argument. Similar interpretations were perceived in the AMIP simulation of CCSM4 model. Further modeling experiments on this warming will be helpful to know the exact mechanism behind it.

  12. Microstructure of absorber layers in CdTe/CdS solar cells

    International Nuclear Information System (INIS)

    Cousins, M.A.

    2001-04-01

    This work concerns the microstructure of CSS-grown CdTe layers used for CdTe/CdS solar cells. Particular attention is given to how the development of microstructure on annealing with CdCl 2 may correlate with increases in efficiency. By annealing pressed pellets of bulk CdTe powder, it is shown that microstructural change does occur on heating the material, enhanced by the inclusion of CdCl 2 flux. However, the temperature required to cause significant effects is demonstrated to be higher than that at which heavy oxidation takes place. The dynamics of this oxidation are also examined. To investigate microstructural evolution in thin-films of CdTe, bi-layers of CdTe and CdS are examined by bevelling, thus revealing the microstructure to within ∼1 μm of the interface. This allows optical microscopy and subsequent image analysis of grain structure. The work shows that the grain-size, which is well described by the Rayleigh distribution, varies linearly throughout the layer, but is invariant under CdCl 2 treatment. Electrical measurements on these bi-layers, however, showed increased efficiency, as is widely reported. This demonstrates that the efficiency of these devices is not dictated by the bulk microstructure. Further, the region within 1 μm of the interface, of similar bi-layers to above, is examined by plan-view TEM. This reveals five-fold grain-growth on CdCl 2 treatment. Moreover, these grains show a considerably smaller grain size than expected from extrapolating the linear trend in the bulk. These observations are explained in terms of the pinning of the CdTe grain size to the underlying CdS, and the small grain size this causes. A simple model was proposed for a link between the grain-growth to the efficiency improvement. The study also examines the behaviour of defects within grains upon CdCl 2 treatment provided the first direct evidence of recovery on CdCl 2 treatment in this system. Finally, a computer model is presented to describe the evolution of

  13. Destiny of earthward streaming plasma in the plasmasheet boundary layer

    Science.gov (United States)

    Green, J. L.; Horwitz, J. L.

    1986-01-01

    The dynamics of the earth's magnetotail have been investigated, and it has become clear that the plasmasheet boundary layer field lines map into the Region I Field-Aligned Currents (FAC) of the auroral zone. It is pointed out that the role of earthward streaming ions in the plasmasheet boundary layer may be of fundamental importance in the understanding of magnetotail dynamics, auroral zone physics, and especially for ionospheric-magnetospheric interactions. The present paper has the objective to evaluate propagation characteristics for the earthward streaming ions observed in the plasmasheet boundary layer. An investigation is conducted of the propagation characteristics of protons in the plasmasheet boundary layer using independent single particle dynamics, and conclusions are discussed. The density of earthward streaming ions found in the plasmasheet boundary layer should include the ring current as well as the auroral zone precipitaiton and inner plasmasheet regions of the magnetosphere.

  14. Ensemble using different Planetary Boundary Layer schemes in WRF model for wind speed and direction prediction over Apulia region

    Science.gov (United States)

    Tateo, Andrea; Marcello Miglietta, Mario; Fedele, Francesca; Menegotto, Micaela; Monaco, Alfonso; Bellotti, Roberto

    2017-04-01

    The Weather Research and Forecasting mesoscale model (WRF) was used to simulate hourly 10 m wind speed and direction over the city of Taranto, Apulia region (south-eastern Italy). This area is characterized by a large industrial complex including the largest European steel plant and is subject to a Regional Air Quality Recovery Plan. This plan constrains industries in the area to reduce by 10 % the mean daily emissions by diffuse and point sources during specific meteorological conditions named wind days. According to the Recovery Plan, the Regional Environmental Agency ARPA-PUGLIA is responsible for forecasting these specific meteorological conditions with 72 h in advance and possibly issue the early warning. In particular, an accurate wind simulation is required. Unfortunately, numerical weather prediction models suffer from errors, especially for what concerns near-surface fields. These errors depend primarily on uncertainties in the initial and boundary conditions provided by global models and secondly on the model formulation, in particular the physical parametrizations used to represent processes such as turbulence, radiation exchange, cumulus and microphysics. In our work, we tried to compensate for the latter limitation by using different Planetary Boundary Layer (PBL) parameterization schemes. Five combinations of PBL and Surface Layer (SL) schemes were considered. Simulations are implemented in a real-time configuration since our intention is to analyze the same configuration implemented by ARPA-PUGLIA for operational runs; the validation is focused over a time range extending from 49 to 72 h with hourly time resolution. The assessment of the performance was computed by comparing the WRF model output with ground data measured at a weather monitoring station in Taranto, near the steel plant. After the analysis of the simulations performed with different PBL schemes, both simple (e.g. average) and more complex post-processing methods (e.g. weighted average

  15. Low temperature plasma-enhanced atomic layer deposition of thin vanadium nitride layers for copper diffusion barriers

    Energy Technology Data Exchange (ETDEWEB)

    Rampelberg, Geert; Devloo-Casier, Kilian; Deduytsche, Davy; Detavernier, Christophe [Department of Solid State Sciences, Ghent University, Krijgslaan 281/S1, B-9000 Ghent (Belgium); Schaekers, Marc [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Blasco, Nicolas [Air Liquide Electronics US, L.P., 46401 Landing Parkway, Fremont, California 94538 (United States)

    2013-03-18

    Thin vanadium nitride (VN) layers were grown by atomic layer deposition using tetrakis(ethylmethylamino)vanadium and NH{sub 3} plasma at deposition temperatures between 70 Degree-Sign C and 150 Degree-Sign C on silicon substrates and polymer foil. X-ray photoelectron spectroscopy revealed a composition close to stoichiometric VN, while x-ray diffraction showed the {delta}-VN crystal structure. The resistivity was as low as 200 {mu}{Omega} cm for the as deposited films and further reduced to 143 {mu}{Omega} cm and 93 {mu}{Omega} cm by annealing in N{sub 2} and H{sub 2}/He/N{sub 2}, respectively. A 5 nm VN layer proved to be effective as a diffusion barrier for copper up to a temperature of 720 Degree-Sign C.

  16. Preparation of Flame Retardant Polyacrylonitrile Fabric Based on Sol-Gel and Layer-by-Layer Assembly.

    Science.gov (United States)

    Ren, Yuanlin; Huo, Tongguo; Qin, Yiwen; Liu, Xiaohui

    2018-03-23

    This paper aims to develop a novel method, i.e., sol-gel combined with layer-by-layer assembly technology, to impart flame retardancy on polyacrylonitrile (PAN) fabrics. Silica-sol was synthesized via the sol-gel process and acted as cationic solution, and phytic acid (PA) was used as the anionic medium. Flame-retardant-treated PAN fabric (FR-PAN) could achieve excellent flame retardancy with 10 bilayer (10BL) coating through layer-by-layer assembly. The structure of the fabrics was characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The thermal stability and flame retardancy were evaluated by thermogravimetric (TG) analysis, cone calorimetry (CC) and limiting oxygen index (LOI). The LOI value of the coated fabric was up to 33.2 vol % and the char residue at 800 °C also increased to 57 wt %. Cone calorimetry tests revealed that, compared to the control fabric, the peak of heat release rate (PHRR) and total heat release (THR) of FR-PAN decreased by 66% and 73%, respectively. These results indicated that sol-gel combined with layer-by-layer assembly technique could impart PAN fabric with satisfactory flame-retardant properties, showing an efficient flame retardant strategy for PAN fabric.

  17. Plasma and magnetic field characteristics of the distant polar cusp near local noon: The entry layer

    International Nuclear Information System (INIS)

    Paschmann, G.; Haerendel, G.; Sckopke, N.; Rosenbauer, H.; Hedgecock, P.C.

    1976-01-01

    Heos 2 plasma and magnetic field measurements in the distant polar cusp region reveal the existence of a plasma layer on day side field lines just inside the magnetopause. Density and temperature in this layer are nearly the same as they are in the adjacent magnetosheath, but the flow lacks the order existing both in the magnetosheath and in the plasma mantle. Flow directions toward and away from the sun but, in general, parallel to the field lines have been found. The magnetopause (as defined by a sudden rotation of the magnetic field vector) mostly coincides with the transition to ordered magnetosheath flow. The inner boundary of the layer is located just within the outer boundary of the hot ring current plasma. In the region of overlap the hot electrons have the signature of trapped particles, though often at reduced intensity. The magnetic field is strongly fluctuating in magnitude, while its orientation is more stable, consistent with a connection to the earth, but is systematically distorted out of the meridian plane. The layer is thought to be a consequence of the entry of magnetosheath plasma, which does not appear to be unobstructed, as has been claimed in the concept of a magnetospheric cleft. The magnetopause has a cusplike indentation which is elongated in local time. The existence of field-aligned currents (total strength approx. =10 6 A) and their location of flow in the inner part of the entry layer (into the ionosphere before noon and out of it after noon) are inferred from the systematic bending of field lines. It is proposed that the dynamo of the related current system is provided by the transfer of perpendicular momentum resulting from the plasma entry into the layer. The essential features of the entry layer might be compatible with the model of plasma flow through the magnetopause of Levy et al. (1964) if a 'dam' effect caused by the cusp geometry were added

  18. Turbulent Boundary Layer Over Geophysical-like Topographies

    Science.gov (United States)

    Chamorro, L. P.; Hamed, A. M.; Castillo, L.

    2016-12-01

    An experimental investigation of the flow and the turbulence structure over 2D and 3D large-scale wavy walls was performed using high-resolution planar particle image velocimetry in a refractive-index-matching (RIM) channel. Extensive measurements were performed to characterize the developing and developed flows. The 2D wall is described by a sinusoidal wave in the streamwise direction with amplitude to wavelength ratio a/λx = 0.05, while the 3D wall has an additional wave superimposed in the spanwise direction with a/λy = 0.1. The flow over these walls was characterized at Reynolds numbers of 4000 and 40000, based on the bulk velocity and the channel half height. The walls have an amplitude to boundary layer thickness ratio a/δ99 ≈ 0.1 and resemble large-scale and geophysical-like roughnesses found in rivers beds and natural terrain. Instantaneous velocity fields and time-averaged turbulence quantities reveal strong coupling between large-scale topography and the turbulence dynamics near the wall. Turbulence statistics for both walls show the presence of a well-structured shear layer past the roughness crests. Analysis of the turbulent kinetic energy production rate suggests that the shear layer is responsible for the majority of turbulence production across both walls. However, the 3D wall exhibits preferential spanwise flows that are thought to result in the multiple distinctive flow features for the 3D wall including comparatively reduced spanwise vorticity and decreased turbulence levels. Further insight on the effect of roughness three-dimensionality and Reynolds number is drawn in both the developed and developing regions through proper orthogonal decomposition (POD) and quadrant analysis.

  19. Development of an industrial tool to make passivation layers for UV sensors improvement

    Energy Technology Data Exchange (ETDEWEB)

    Larmande, Yannick, E-mail: larmande@lp3.univ-mrs.fr [LP3 Laboratory, UMR 6182 CNRS - Mediterranean University, Campus de Luminy, Case 917, 13 288 Marseille Cedex 9 (France); Ion Beam Services, Rue Gaston Imbert Prolongee, 13 790 Peynier (France); Vervisch, Vanessa; Delaporte, Philippe; Sarnet, Thierry; Sentis, Marc [LP3 Laboratory, UMR 6182 CNRS - Mediterranean University, Campus de Luminy, Case 917, 13 288 Marseille Cedex 9 (France); Etienne, Hasnaa; Torregrosa, Frank [Ion Beam Services, Rue Gaston Imbert Prolongee, 13 790 Peynier (France)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer We have reached a sheet resistance lower than 500 {Omega}/sq for a junction depth of 29 nm and an abruptness of 3 nm/dec. Black-Right-Pointing-Pointer Electrical measurements on diodes have revealed a significant leakage current of around 10{sup -5} A/cm{sup 2}, revealing the presence of defects inside the junction. Black-Right-Pointing-Pointer Light Beam Induced Current (LBIC) characterization has shown that the defects are localized at the edge of the laser beam. - Abstract: Today, the collection of generated charges is a limiting problem for the realization of UV sensors. Indeed, the native silicon oxide of the surface acts as a region of recombination centers . Then, the sensors exhibit a low sensitivity in the UV wavelengths. An approach to overcome this drawback is the realization of a few nanometers thick passivation layer at the surface by creating an ultra-shallow junction (USJ) with a high activation level. The realization of such junctions requires two steps: first, the implantation of dopants which consists in introducing impurities at the surface of the substrate, then the thermal activation of these dopants to obtain the electrical characteristics of the junction. The Plasma Immersion Ion Implantation (PIII) process allows us to implant dopants in a very thin layer (10-20 nm) into the silicon substrate . These impurities are located in interstitial sites in the silicon, and need an activation process to modify the electrical properties of the layer. The step is performed by means of an excimer laser annealing process (ELA) to melt a very thin layer of the silicon substrate and then activate the dopants without diffusion. In the framework of the ALDIP project (Laser Activation of Dopants implanted by Plasma Immersion), IBS Company has developed with its partners a cluster to realize these two steps with industrial production rates and cleanliness. Four-point probe measurements and SIMS analyzes have been used to

  20. Non-destructive testing of layer-to-layer fusion of a 3D print using ultrahigh resolution optical coherence tomography

    Science.gov (United States)

    Israelsen, Niels M.; Maria, Michael; Feuchter, Thomas; Podoleanu, Adrian; Bang, Ole

    2017-06-01

    Within the last decade, 3D printing has moved from a costly approach of building mechanical items to the present state-of-the-art phase where access to 3D printers is now common, both in industry and in private places. The plastic printers are the most common type of 3D printers providing prints that are light, robust and of lower cost. The robustness of the structure printed is only maintained if each layer printed is properly fused to its previously printed layers. In situations where the printed component has to accomplish a key mechanical role there is a need to characterize its mechanical strength. This may only be revealed by in-depth testing in order to discover unwanted air-gaps in the structure. Optical coherence tomography (OCT) is an in-depth imaging method, that is sensitive to variations in the refractive index and therefore can resolve with high resolution translucid samples. We report on volume imaging of a 3D printed block made with 100% PLA fill. By employing ultrahigh resolution OCT (UHR-OCT) we show that some parts of the PLA volume reveal highly scattering interfaces which likely correspond to transitions from one layer to another. In doing so, we document that UHR-OCT can act as a powerful tool that can be used in detecting fractures between layers stemming from insufficient fusion between printed structure layers. UHR-OCT can therefore serve as an useful assessment method of quality of 3D prints.

  1. Global variation in the long-term seasonal changes observed in ionospheric F region data

    Directory of Open Access Journals (Sweden)

    C. J. Scott

    2015-04-01

    Full Text Available Long-term variability has previously been observed in the relative magnitude of annual and semi-annual variations in the critical frequency (related to the peak electron concentration of the ionospheric F2 layer (foF2. In this paper we investigate the global patterns in such variability by calculating the time varying power ratio of semi-annual to annual components seen in ionospheric foF2 data sequences from 77 ionospheric monitoring stations around the world. The temporal variation in power ratios observed at each station was then correlated with the same parameter calculated from similar epochs for the Slough/Chilton data set (for which there exists the longest continuous sequence of ionospheric data. This technique reveals strong regional variation in the data, which bears a striking similarity to the regional variation observed in long-term changes to the height of the ionospheric F2 layer. We argue that since both the height and peak density of the ionospheric F2 region are influenced by changes to thermospheric circulation and composition, the observed long-term and regional variability can be explained by such changes. In the absence of long-term measurements of thermospheric composition, detailed modelling work is required to investigate these processes.

  2. Rocket in situ observation of equatorial plasma irregularities in the region between E and F layers over Brazil

    Directory of Open Access Journals (Sweden)

    S. Savio Odriozola

    2017-03-01

    Full Text Available A two-stage VS-30 Orion rocket was launched from the equatorial rocket launching station in Alcântara, Brazil, on 8 December 2012 soon after sunset (19:00 LT, carrying a Langmuir probe operating alternately in swept and constant bias modes. At the time of launch, ground equipment operated at equatorial stations showed rapid rise in the base of the F layer, indicating the pre-reversal enhancement of the F region vertical drift and creating ionospheric conditions favorable for the generation of plasma bubbles. Vertical profiles of electron density estimated from Langmuir probe data showed wave patterns and small- and medium-scale plasma irregularities in the valley region (100–300 km during the rocket upleg and downleg. These irregularities resemble those detected by the very high frequency (VHF radar installed at Jicamarca and so-called equatorial quasi-periodic echoes. We present evidence suggesting that these observations could be the first detection of this type of irregularity made by instruments onboard a rocket.

  3. The role of organic intertile layer in abalone nacre

    International Nuclear Information System (INIS)

    Meyers, M.A.; Lim, C.T.; Li, A.; Hairul Nizam, B.R.; Tan, E.P.S.; Seki, Y.; McKittrick, J.

    2009-01-01

    Characterization of the growth surfaces removed from red and green abalone (Haliotis) shells shows a terraced cone mode of mineralization in which the organic layer is deposited periodically and regulates the formation of tiles with ∼ 500 nm thickness. The details of the mineral and organic layer surface are revealed by atomic force microscopy; the surface roughness and the thickness of the tiles in the terraces and organic intertile layer were measurement. Nanoindentation experiments at the top of the terraced cones confirm a hardness of the same order as that of completely mineralized surfaces. Indentation of the organic layer provides a force-deflection curve that can be expressed as tension on a centrally-loaded membrane. The results show that the dry organic layer is very stiff and deforms inelastically or cracks under the indenter, whereas in the fully hydrated state it shows a low modulus and strength and great extensibility. This strongly suggests that this organic interlayer acquires considerable strength and stiffness as a result of the drying process, which is consistent with a T g of approximately 200 deg. C for chitin. The chitin network that forms the structural component of the intertile layer is revealed and the orientation and spacing are measured. Terraced cones broken under the force of a flexing and shrinking organic layer enable the estimation of the tensile strength of the abalone when loaded through the fracture of the mineral bridges. Calculations show consistency with earlier tensile strength measurements of < 10 MPa.

  4. Coupling of magnetopause-boundary layer to the polar ionosphere

    International Nuclear Information System (INIS)

    Wei, C.Q.; Lee, L.C.

    1993-01-01

    The authors develop a model which seeks to explain ultraviolet auroral images from the Viking satellite which show periodic bright regions which resemble open-quotes beadsclose quotes or open-quotes pearlsclose quotes aligned along the postnoon auroral oval. ULF geomagnetic pulsations observed in the cusp region are also addressed by this model. The model addresses plasma dynamics in the low-latitude boundary layer and interactions with the polar ionosphere by means of field-aligned current. The Kelvin-Helmholtz instability can develop in the presence of driven plasma flow, which can lead to the formation and growth of plasma vortices in the boundary layer. The finite conductivity of the earth ionosphere causes these vortices to decay. However regions of enhanced field-aligned power density in the postnoon auroral oval can be associated with field-aligned current filaments and boundary layer vortices. These structures may explain the observed bright spots. The authors also discuss the frequency spectrum and the polarization state of the pulsations

  5. Heterologous protein display on the cell surface of lactic acid bacteria mediated by the s-layer protein

    Directory of Open Access Journals (Sweden)

    Han Lanlan

    2011-10-01

    Full Text Available Abstract Background Previous studies have revealed that the C-terminal region of the S-layer protein from Lactobacillus is responsible for the cell wall anchoring, which provide an approach for targeting heterologous proteins to the cell wall of lactic acid bacteria (LAB. In this study, we developed a new surface display system in lactic acid bacteria with the C-terminal region of S-layer protein SlpB of Lactobacillus crispatus K2-4-3 isolated from chicken intestine. Results Multiple sequence alignment revealed that the C-terminal region (LcsB of Lb. crispatus K2-4-3 SlpB had a high similarity with the cell wall binding domains SA and CbsA of Lactobacillus acidophilus and Lb. crispatus. To evaluate the potential application as an anchoring protein, the green fluorescent protein (GFP or beta-galactosidase (Gal was fused to the N-terminus of the LcsB region, and the fused proteins were successfully produced in Escherichia coli, respectively. After mixing them with the non-genetically modified lactic acid bacteria cells, the fused GFP-LcsB and Gal-LcsB were functionally associated with the cell surface of various lactic acid bacteria tested. In addition, the binding capacity could be improved by SDS pretreatment. Moreover, both of the fused proteins could simultaneously bind to the surface of a single cell. Furthermore, when the fused DNA fragment of gfp:lcsB was inserted into the Lactococcus lactis expression vector pSec:Leiss:Nuc, the GFP could not be secreted into the medium under the control of the nisA promoter. Western blot, in-gel fluorescence assay, immunofluorescence microscopy and SDS sensitivity analysis confirmed that the GFP was successfully expressed onto the cell surface of L. lactis with the aid of the LcsB anchor. Conclusion The LcsB region can be used as a functional scaffold to target the heterologous proteins to the cell surfaces of lactic acid bacteria in vitro and in vivo, and has also the potential for biotechnological

  6. Transitional boundary layer in low-Prandtl-number convection at high Rayleigh number

    Science.gov (United States)

    Schumacher, Joerg; Bandaru, Vinodh; Pandey, Ambrish; Scheel, Janet

    2016-11-01

    The boundary layer structure of the velocity and temperature fields in turbulent Rayleigh-Bénard flows in closed cylindrical cells of unit aspect ratio is revisited from a transitional and turbulent viscous boundary layer perspective. When the Rayleigh number is large enough the boundary layer dynamics at the bottom and top plates can be separated into an impact region of downwelling plumes, an ejection region of upwelling plumes and an interior region (away from side walls) that is dominated by a shear flow of varying orientation. This interior plate region is compared here to classical wall-bounded shear flows. The working fluid is liquid mercury or liquid gallium at a Prandtl number of Pr = 0 . 021 for a range of Rayleigh numbers of 3 ×105 Deutsche Forschungsgemeinschaft.

  7. Instability limits for spontaneous double layer formation

    International Nuclear Information System (INIS)

    Carr, J. Jr.; Galante, M. E.; McCarren, D.; Scime, E. E.; Sears, S.; VanDervort, R. W.; Magee, R. M.; Reynolds, E.

    2013-01-01

    We present time-resolved measurements that demonstrate that large amplitude electrostatic instabilities appear in pulsed, expanding helicon plasmas at the same time as particularly strong double layers appear in the expansion region. A significant cross-correlation between the electrostatic fluctuations and fluctuations in the number of ions accelerated by the double layer electric field is observed. No correlation is observed between the electrostatic fluctuations and ions that have not passed through the double layer. These measurements confirm that the simultaneous appearance of the electrostatic fluctuations and the double layer is not simple coincidence. In fact, the accelerated ion population is responsible for the growth of the instability. The double layer strength, and therefore, the velocity of the accelerated ions, is limited by the appearance of the electrostatic instability

  8. CVD grown 2D MoS{sub 2} layers: A photoluminescence and fluorescence lifetime imaging study

    Energy Technology Data Exchange (ETDEWEB)

    Oezden, Ayberk; Madenoglu, Buesra [Department of Materials Science and Engineering, Faculty of Engineering, Anadolu University, Eskisehir (Turkey); Sar, Hueseyin; Ay, Feridun; Perkgoez, Nihan Kosku [Department of Electrical and Electronics Engineering, Faculty of Engineering, Anadolu University, Eskisehir (Turkey); Yeltik, Aydan [Department of Physics, UNAM Institute of Materials Science and Nanotechnology, Bilkent University, Ankara (Turkey); Sevik, Cem [Department of Mechanical Engineering, Faculty of Engineering, Anadolu University, Eskisehir (Turkey)

    2016-11-15

    In this letter, we report on the fluorescence lifetime imaging and accompanying photoluminescence properties of a chemical vapour deposition (CVD) grown atomically thin material, MoS{sub 2}. μ-Raman, μ-photoluminescence (PL) and fluorescence lifetime imaging microscopy (FLIM) are utilized to probe the fluorescence lifetime and photoluminescence properties of individual flakes of MoS{sub 2} films. Usage of these three techniques allows identification of the grown layers, grain boundaries, structural defects and their relative effects on the PL and fluorescence lifetime spectra. Our investigation on individual monolayer flakes reveals a clear increase of the fluorescence lifetime from 0.3 ns to 0.45 ns at the edges with respect to interior region. On the other hand, investigation of the film layer reveals quenching of PL intensity and lifetime at the grain boundaries. These results could be important for applications where the activity of edges is important such as in photocatalytic water splitting. Finally, it has been demonstrated that PL mapping and FLIM are viable techniques for the investigation of the grain-boundaries. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. The formation of multiple layers of ice particles in the polar summer mesopause region

    Directory of Open Access Journals (Sweden)

    H. Li

    2016-01-01

    Full Text Available This paper presents a two-dimensional theoretical model to study the formation process of multiple layers of small ice particles in the polar summer mesosphere as measured by rockets and associated with polar mesosphere summer echoes (PMSE. The proposed mechanism primarily takes into account the transport processes induced by gravity waves through collision coupling between the neutral atmosphere and the ice particles. Numerical solutions of the model indicate that the dynamic influence of wind variation induced by gravity waves can make a significant contribution to the vertical and horizontal transport of ice particles and ultimately transform them into thin multiple layers. Additionally, the pattern of the multiple layers at least partially depends on the vertical wavelength of the gravity wave, the ice particle size and the wind velocity. The results presented in this paper will be helpful to better understand the occurrence of multiple layers of PMSE as well as its variation process.

  10. Probing region-specific microstructure of human cortical areas using high angular and spatial resolution diffusion MRI.

    Science.gov (United States)

    Aggarwal, Manisha; Nauen, David W; Troncoso, Juan C; Mori, Susumu

    2015-01-15

    Regional heterogeneity in cortical cyto- and myeloarchitecture forms the structural basis of mapping of cortical areas in the human brain. In this study, we investigate the potential of diffusion MRI to probe the microstructure of cortical gray matter and its region-specific heterogeneity across cortical areas in the fixed human brain. High angular resolution diffusion imaging (HARDI) data at an isotropic resolution of 92-μm and 30 diffusion-encoding directions were acquired using a 3D diffusion-weighted gradient-and-spin-echo sequence, from prefrontal (Brodmann area 9), primary motor (area 4), primary somatosensory (area 3b), and primary visual (area 17) cortical specimens (n=3 each) from three human subjects. Further, the diffusion MR findings in these cortical areas were compared with histological silver impregnation of the same specimens, in order to investigate the underlying architectonic features that constitute the microstructural basis of diffusion-driven contrasts in cortical gray matter. Our data reveal distinct and region-specific diffusion MR contrasts across the studied areas, allowing delineation of intracortical bands of tangential fibers in specific layers-layer I, layer VI, and the inner and outer bands of Baillarger. The findings of this work demonstrate unique sensitivity of diffusion MRI to differentiate region-specific cortical microstructure in the human brain, and will be useful for myeloarchitectonic mapping of cortical areas as well as to achieve an understanding of the basis of diffusion NMR contrasts in cortical gray matter. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. K -shell decomposition reveals hierarchical cortical organization of the human brain

    International Nuclear Information System (INIS)

    Lahav, Nir; Ksherim, Baruch; Havlin, Shlomo; Ben-Simon, Eti; Maron-Katz, Adi; Cohen, Reuven

    2016-01-01

    In recent years numerous attempts to understand the human brain were undertaken from a network point of view. A network framework takes into account the relationships between the different parts of the system and enables to examine how global and complex functions might emerge from network topology. Previous work revealed that the human brain features ‘small world’ characteristics and that cortical hubs tend to interconnect among themselves. However, in order to fully understand the topological structure of hubs, and how their profile reflect the brain’s global functional organization, one needs to go beyond the properties of a specific hub and examine the various structural layers that make up the network. To address this topic further, we applied an analysis known in statistical physics and network theory as k-shell decomposition analysis. The analysis was applied on a human cortical network, derived from MRI/DSI data of six participants. Such analysis enables us to portray a detailed account of cortical connectivity focusing on different neighborhoods of inter-connected layers across the cortex. Our findings reveal that the human cortex is highly connected and efficient, and unlike the internet network contains no isolated nodes. The cortical network is comprised of a nucleus alongside shells of increasing connectivity that formed one connected giant component, revealing the human brain’s global functional organization. All these components were further categorized into three hierarchies in accordance with their connectivity profile, with each hierarchy reflecting different functional roles. Such a model may explain an efficient flow of information from the lowest hierarchy to the highest one, with each step enabling increased data integration. At the top, the highest hierarchy (the nucleus) serves as a global interconnected collective and demonstrates high correlation with consciousness related regions, suggesting that the nucleus might serve as a

  12. Bipolar H II regions produced by cloud-cloud collisions

    Science.gov (United States)

    Whitworth, Anthony; Lomax, Oliver; Balfour, Scott; Mège, Pierre; Zavagno, Annie; Deharveng, Lise

    2018-05-01

    We suggest that bipolar H II regions may be the aftermath of collisions between clouds. Such a collision will produce a shock-compressed layer, and a star cluster can then condense out of the dense gas near the center of the layer. If the clouds are sufficiently massive, the star cluster is likely to contain at least one massive star, which emits ionizing radiation, and excites an H II region, which then expands, sweeping up the surrounding neutral gas. Once most of the matter in the clouds has accreted onto the layer, expansion of the H II region meets little resistance in directions perpendicular to the midplane of the layer, and so it expands rapidly to produce two lobes of ionized gas, one on each side of the layer. Conversely, in directions parallel to the midplane of the layer, expansion of the H II region stalls due to the ram pressure of the gas that continues to fall towards the star cluster from the outer parts of the layer; a ring of dense neutral gas builds up around the waist of the bipolar H II region, and may spawn a second generation of star formation. We present a dimensionless model for the flow of ionized gas in a bipolar H II region created according to the above scenario, and predict the characteristics of the resulting free-free continuum and recombination-line emission. This dimensionless model can be scaled to the physical parameters of any particular system. Our intention is that these predictions will be useful in testing the scenario outlined above, and thereby providing indirect support for the role of cloud-cloud collisions in triggering star formation.

  13. Reference Models for Multi-Layer Tissue Structures

    Science.gov (United States)

    2016-09-01

    function of multi-layer tissues (etiology and management of pressure ulcers ). What was the impact on other disciplines? As part of the project, a data...simplification to develop cost -effective models of surface manipulation of multi-layer tissues. Deliverables. Specimen- (or subject) and region-specific...simplification to develop cost -effective models of surgical manipulation. Deliverables. Specimen-specific surrogate models of upper legs confirmed against data

  14. The Global Terrestrial Network for Permafrost Database: metadata statistics and prospective analysis on future permafrost temperature and active layer depth monitoring site distribution

    Science.gov (United States)

    Biskaborn, B. K.; Lanckman, J.-P.; Lantuit, H.; Elger, K.; Streletskiy, D. A.; Cable, W. L.; Romanovsky, V. E.

    2015-03-01

    The Global Terrestrial Network for Permafrost (GTN-P) provides the first dynamic database associated with the Thermal State of Permafrost (TSP) and the Circumpolar Active Layer Monitoring (CALM) programs, which extensively collect permafrost temperature and active layer thickness data from Arctic, Antarctic and Mountain permafrost regions. The purpose of the database is to establish an "early warning system" for the consequences of climate change in permafrost regions and to provide standardized thermal permafrost data to global models. In this paper we perform statistical analysis of the GTN-P metadata aiming to identify the spatial gaps in the GTN-P site distribution in relation to climate-effective environmental parameters. We describe the concept and structure of the Data Management System in regard to user operability, data transfer and data policy. We outline data sources and data processing including quality control strategies. Assessment of the metadata and data quality reveals 63% metadata completeness at active layer sites and 50% metadata completeness for boreholes. Voronoi Tessellation Analysis on the spatial sample distribution of boreholes and active layer measurement sites quantifies the distribution inhomogeneity and provides potential locations of additional permafrost research sites to improve the representativeness of thermal monitoring across areas underlain by permafrost. The depth distribution of the boreholes reveals that 73% are shallower than 25 m and 27% are deeper, reaching a maximum of 1 km depth. Comparison of the GTN-P site distribution with permafrost zones, soil organic carbon contents and vegetation types exhibits different local to regional monitoring situations on maps. Preferential slope orientation at the sites most likely causes a bias in the temperature monitoring and should be taken into account when using the data for global models. The distribution of GTN-P sites within zones of projected temperature change show a high

  15. Nanoscopic characterization of the water vapor-salt interfacial layer reveals a unique biphasic adsorption process

    Science.gov (United States)

    Yang, Liu; He, Jianfeng; Shen, Yi; Li, Xiaowei; Sun, Jielin; Czajkowsky, Daniel M.; Shao, Zhifeng

    2016-08-01

    Our quantitative understanding of water adsorption onto salt surfaces under ambient conditions is presently quite poor owing to the difficulties in directly characterizing this interfacial layer under these conditions. Here we determine the thickness of the interfacial layer on NaCl at different relative humidities (RH) based on a novel application of atomic force spectroscopy and capillary condensation theory. In particular, we take advantage of the microsecond-timescale of the capillary condensation process to directly resolve the magnitude of its contribution in the tip-sample interaction, from which the interfacial water thickness is determined. Further, to correlate this thickness with salt dissolution, we also measure surface conductance under similar conditions. We find that below 30% RH, there is essentially only the deposition of water molecules onto this surface, typical of conventional adsorption onto solid surfaces. However, above 30% RH, adsorption is simultaneous with the dissolution of ions, unlike conventional adsorption, leading to a rapid increase of surface conductance. Thus, water adsorption on NaCl is an unconventional biphasic process in which the interfacial layer not only exhibits quantitative differences in thickness but also qualitative differences in composition.

  16. Regional distribution of volcaniclastic layer and its implication for segmentation of the Nankai seismogenic zone

    Science.gov (United States)

    Sasaki, T.; Lim, J.; Higashi, M.; Park, J.

    2010-12-01

    The Nankai Trough is known as one of the best-suited convergent plate margins for studying accretionary prism growth as well as subduction zone earthquakes. Along the Nankai accretionary margin off southwest Japan, the Shikoku Basin which formed 26-15 Ma as backarc spreading in the Philippine Sea Plate is being subducted about 4 cm/year to the northwest. The Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) penetrated the Nankai accretionary prism and the incoming sedimentary section along the Ashizuri and Muroto transects, off Shikoku Island. Also, Integrated Ocean Drilling Program (IODP), which represented just one part of a multi-stage project known as the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) has been conducting drilling cruises now. IODP Expedition 322 in 2009, the coring was carried out at two drilling sites on the northern part of the Shikoku Basin in the subducting Philippine Sea plate. One of the major achievements of Expedition 322 is a discovery of late Miocene (10.2-7.6 Ma) tuffaceous and volcaniclastic sandstone layer (Underwood et al., IODP Prel. Rept. 322, 2009) that has not been previously recognized in the Nankai Trough. Based on age and volcanic sand content analysis, these volcaniclastic layers were unique to the Shikoku Basin off Kii Peninsula. The closest source of this volcanic layer was supposed to be the Izu-Bonin arc. Subducted sediments ultimately affect subduction zone geochemistry, thermal structure, and seismogenesis. High porosity of the volcaniclastic sandstone layer suggests the transportation of fluid to the subduction zone, it might affect the initiation and evolution of the decollement zone or plate boundary fault in the Nankai Trough. We interpreted single channel and multichannel seismic reflection profiles that have been acquired in the Nankai Trough margin by Japan Agency for Marine-Earth Science and Technology (JAMSTEC) since the year of 1997. We tried to map the major seismic layers such as

  17. A simulation study of the vortex structure in the low-latitude boundary layer

    International Nuclear Information System (INIS)

    Wei, C.Q.; Lee, L.C.; La Belle-Hamer, A.L.

    1990-01-01

    Satellite observations indicate that the plasma density and the flow velocity are highly variable in the low-latitude boundary layer. The thickness of the boundary layer is also highly variable and appears to increase with increasing longitudinal distance from the subsolar point. In this paper plasma dynamics in the low-latitude boundary layer region is studied on the basis of a two-dimensional incompressible bydrodynamic numerical model. In the simulation, plasma is driven into the boundary layer region by imposing a diffusion flux along the magnetopause. The vortex motions associated with the Kelvin-Helmholtz instability are observed in the simulation. The resulting vortex structures in the plasma density and the flow velocity may coalesce as they are convected tailward, causing them to grow in size. The boundary layer thickness increases with increasing longitudinal distance from the subsolar point in accord with satellite observations. The plasma density and the flow velocity are positively correlated. A mixing region is formed where magnetosheath plasma and magnetospheric plasma mix due to the vortex motions. In the later stage of development, a density plateau is formed in the central part of the boundary layer. Many features of the satellite observations of the boundary layer can be explained using the numerical model. The simulation results also predict that the vortices generated in the postnoon (prenoon) boundary layer lead to the presence of localized upward (downward) field-aligned currents in both the northern and the southern polar ionospheres. The upward field-aligned currents in turn may lead to the formation of dayside auroral patches observed in the postnoon region

  18. Large-eddy simulation of passive shock-wave/boundary-layer interaction control

    International Nuclear Information System (INIS)

    Pasquariello, Vito; Grilli, Muzio; Hickel, Stefan; Adams, Nikolaus A.

    2014-01-01

    Highlights: • The present study investigates a passive flow-control technique for shock-wave/boundary-layer interaction. • The control configuration consists of local suction and injection through a pressure feedback duct. • Implicit LES have been conducted for three different suction locations. • Suction reduces the size of the separation zone. • Turbulence amplification and reflected shock dynamics can be significantly reduced. - Abstract: We investigate a passive flow-control technique for the interaction of an oblique shock generated by an 8.8° wedge with a turbulent boundary-layer at a free-stream Mach number of Ma ∞ =2.3 and a Reynolds number based on the incoming boundary-layer thickness of Re δ 0 =60.5×10 3 by means of large-eddy simulation (LES). The compressible Navier–Stokes equations in conservative form are solved using the adaptive local deconvolution method (ALDM) for physically consistent subgrid scale modeling. Emphasis is placed on the correct description of turbulent inflow boundary conditions, which do not artificially force low-frequency periodic motion of the reflected shock. The control configuration combines suction inside the separation zone and blowing upstream of the interaction region by a pressure feedback through a duct embedded in the wall. We vary the suction location within the recirculation zone while the injection position is kept constant. Suction reduces the size of the separation zone with strongest effect when applied in the rear part of the separation bubble. The analysis of wall-pressure spectra reveals that all control configurations shift the high-energy low-frequency range to higher frequencies, while the energy level is significantly reduced only if suction acts in the rear part of the separated zone. In that case also turbulence production within the interaction region is significantly reduced as a consequence of mitigated reflected shock dynamics and near-wall flow acceleration

  19. Determination of stress distribution in III-V single crystal layers for heterogeneous integration applications

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, M.; Hayashi, S. [Dept. of Materials Science and Engineering, University of California, Los Angeles, CA 90095 (United States); Goorsky, M.S.; Sandhu, R.; Chang-Chien, P.; Gutierrez-Aitken, A.; Tsai, R. [Northrop Grumman Space Technology, Redondo Beach, CA 90278 (United States); Noori, A.; Poust, B. [Dept. of Materials Science and Engineering, University of California, Los Angeles, CA 90095 (United States); Northrop Grumman Space Technology, Redondo Beach, CA 90278 (United States)

    2007-08-15

    Double crystal X-ray diffraction imaging and a variable temperature stage are employed to determine the stress distribution in heterogeneous wafer bonded layers though the superposition of images produced at different rocking curve angles. The stress distribution in InP layers transferred to a silicon substrate at room temperature exhibits an anticlastic deformation, with different regions of the wafer experiencing different signs of curvature. Measurements at elevated temperatures ({<=}125 C) reveals that differences in thermal expansion coefficients dominate the stress and that interfacial particulates introduce very high local stress gradients that increase with increased temperature. For thinned GaAs substrates (100 {mu}m) bonded using patterned metal interlayers to a separate GaAs substrate at {approx}200 C, residual stresses are produced at room temperature due to local stress points from metallization contacts and vias and the complex stress patterns can be observed using the diffraction imaging technique. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Multi-Layered Stratification in the Baltic Sea: Insight from a Modeling Study with Reference to Environmental Conditions

    Directory of Open Access Journals (Sweden)

    Bijan Dargahi

    2017-01-01

    Full Text Available The hydrodynamic and transport characteristics of the Baltic Sea in the period 2000–2009 were studied using a fully calibrated and validated 3D hydrodynamic model with a horizontal resolution of 4.8 km. This study provided new insight into the type and dynamics of vertical structure in the Baltic Sea, not considered in previous studies. Thermal and salinity stratification are both addressed, with a focus on the structural properties of the layers. The detection of cooler regions (dicothermal within the layer structure is an important finding. The detailed investigation of thermal stratification for a 10-year period (i.e., 2000–2009 revealed some new features. A multilayered structure that contains several thermocline and dicothermal layers was identified from this study. Statistical analysis of the simulation results made it possible to derive the mean thermal stratification properties, expressed as mean temperatures and the normalized layer thicknesses. The three-layered model proposed by previous investigators appears to be valid only during the winter periods; for other periods, a multi-layered structure with more than five layers has been identified during this investigation. This study provides detailed insight into thermal and salinity stratification in the Baltic Sea during a recent decade that can be used as a basis for diverse environmental assessments. It extends previous studies on stratification in the Baltic Sea regarding both the extent and the nature of stratification.

  1. New hybrid lead iodides: From one-dimensional chain to two-dimensional layered perovskite structure

    International Nuclear Information System (INIS)

    Xiong, Kecai; Liu, Wei; Teat, Simon J.; An, Litao; Wang, Hao; Emge, Thomas J.; Li, Jing

    2015-01-01

    Two new hybrid lead halides (H 2 BDA)[PbI 4 ] (1) (H 2 BDA=1,4-butanediammonium dication) and (HNPEIM)[PbI 3 ] (2) (HNPEIM=N-​phenyl-ethanimidamidine cation) have been synthesized and structurally characterized. X-ray diffraction analyses reveal that compound 1 features a two-dimensional corner-sharing perovskite layer whereas compound 2 contains one-dimensional edge-sharing double chains. The N-​phenyl-ethanimidamidine cation within compound 2 was generated in-situ under solvothermal conditions. The optical absorption spectra collected at room temperature suggest that both compounds are semiconductors having direct band gaps, with estimated values of 2.64 and 2.73 eV for 1 and 2, respectively. Results from the density functional theory (DFT) calculations are consistent with the experimental data. Density of states (DOS) analysis reveals that in both compounds 1 and 2, the energy states in the valence band maximum region are iodine 5p atomic orbitals with a small contribution from lead 6s, while in the region of conduction band minimum, the major contributions are from the inorganic (Pb 6p atomic orbitals) and organic components (C and N 2p atomic orbitals) in compound 1 and 2, respectively. - Graphical abstract: Two new hybrid lead halides built on one-dimensional edge-sharing double chains and two-dimensional corner-sharing perovskite layers are synthesized and their structural and electronic properties are analyzed. - Highlights: • Two new hybrid lead iodides are designed, synthesized, and characterized. • They are closely related to, but different from, perovskite structures. • The electronic properties of both compounds are analyzed by DFT calculations

  2. New hybrid lead iodides: From one-dimensional chain to two-dimensional layered perovskite structure

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Kecai; Liu, Wei [Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854 (United States); Teat, Simon J. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); An, Litao; Wang, Hao; Emge, Thomas J. [Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854 (United States); Li, Jing, E-mail: jingli@rutgers.edu [Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854 (United States)

    2015-10-15

    Two new hybrid lead halides (H{sub 2}BDA)[PbI{sub 4}] (1) (H{sub 2}BDA=1,4-butanediammonium dication) and (HNPEIM)[PbI{sub 3}] (2) (HNPEIM=N-​phenyl-ethanimidamidine cation) have been synthesized and structurally characterized. X-ray diffraction analyses reveal that compound 1 features a two-dimensional corner-sharing perovskite layer whereas compound 2 contains one-dimensional edge-sharing double chains. The N-​phenyl-ethanimidamidine cation within compound 2 was generated in-situ under solvothermal conditions. The optical absorption spectra collected at room temperature suggest that both compounds are semiconductors having direct band gaps, with estimated values of 2.64 and 2.73 eV for 1 and 2, respectively. Results from the density functional theory (DFT) calculations are consistent with the experimental data. Density of states (DOS) analysis reveals that in both compounds 1 and 2, the energy states in the valence band maximum region are iodine 5p atomic orbitals with a small contribution from lead 6s, while in the region of conduction band minimum, the major contributions are from the inorganic (Pb 6p atomic orbitals) and organic components (C and N 2p atomic orbitals) in compound 1 and 2, respectively. - Graphical abstract: Two new hybrid lead halides built on one-dimensional edge-sharing double chains and two-dimensional corner-sharing perovskite layers are synthesized and their structural and electronic properties are analyzed. - Highlights: • Two new hybrid lead iodides are designed, synthesized, and characterized. • They are closely related to, but different from, perovskite structures. • The electronic properties of both compounds are analyzed by DFT calculations.

  3. Localization of excitons by molecular layer formation in a polymer film

    International Nuclear Information System (INIS)

    Chattopadhyay, S.; Datta, A.

    2005-01-01

    Spin coated films of atactic polystyrene of two different molecular weights have been studied with uv spectroscopy and x-ray reflectivity, the film thickness (d) varying from ∼2R g to ∼12R g where R g is the unperturbed radius of gyration of the polymer. uv extinction due to the pure electronic singlet 1 A 1g → 1 E 1u is seen to increase with d -1 for 4R g ≤d≤12R g (region 1). This suggests excitonic interaction along d. The variation of total exciton energy (E) of the A 1g →E 1u singlet with d in region 1 can be well explained by formation of linear J-aggregates of polystyrene molecules, in a lattice with spacing 'a' (in A) R g g , along d. Atomic force microscopic images of the films show the presence of 'spheres' distributed randomly on film surfaces with in-plane dimensions matching a. From the variation of E with d -2 the effective mass (m eff ) of the exciton is also determined. For R g g (region 2) the extinction and E become essentially independent of d, indicating exciton localization along d, and the value of m eff becomes very large. This enhancement in the effective mass maybe used to quantify localization. The variations of electron density (ρ) with d, i.e., the electron density profiles (EDPs) of the films extracted from x-ray reflectivity studies, indicate formation of layers with period 'b' (in A), R g g parallel to substrate surface in region 2 and a constant ρ film in region 1. On raising the temperature of a typical film to 60 deg. C, the layering was seen to almost vanish, as obtained from both the EDP and the Patterson function of the reflectivity profile. The close correspondence between 'a' and 'b' indicates that the molecules forming the J-aggregates form the layers, too. The average difference in ρ between successive extrema in the EDPs in region 2, denoted by δ, can be used as the order parameter for the layering transition. For PS-5, δ>0 at d≅4R g , where the exciton is still delocalized. Layering reduces the Hamaker

  4. A theory for natural convection turbulent boundary layers next to heated vertical surfaces

    International Nuclear Information System (INIS)

    George, W.K. Jr.; Capp, S.P.

    1979-01-01

    The turbulent natural convection boundary layer next to a heated vertical surface is analyzed by classical scaling arguments. It is shown that the fully developed turbulent boundary layer must be treated in two parts: and outer region consisting of most of the boundary layer in which viscous and conduction terms are negligible and an inner region in which the mean convection terms are negligible. The inner layer is identified as a constant heat flux layer. A similarity analysis yields universal profiles for velocity and temperature in the outer and constant heat flux layers. An asymptotic matching of these profiles in an intermediate layer (the buoyant sublayer) yields analytical expressions for the buoyant sublayer profiles. Asymptotic heat transfer and friction laws are obtained for the fully developed boundary layers. Finally, conductive and thermo-viscous sublayers characterized by a linear variation of velocity and temperature are shown to exist at the wall. All predictions are seen to be in excellent agreement with the abundant experimental data. (author)

  5. Effective Clusters as Territorial Performance Engines in a Regional Development Strategy - A Triple-Layer DEA Assessment of the Aviation Valley in Poland

    Directory of Open Access Journals (Sweden)

    Karima Kourtit

    2017-08-01

    country. A new approach based on a triple-layer architecture will be adopted here, viz.: a quantitative comparative analysis of the 16 Polish ‘voivodships’ (main administrative regions in the country, at a NUTS-2 level, a benchmark analysis of the 25 counties (‘powiats’ within the Podkarpackie voivodship (at a NUTS-4 level, and an effective industrial cluster analysis on the basis of the individual aviation firms located in the Podkarpackie region. In each step an extended Data Envelopment Analysis (DEA, characterised by a merger of a Slack-Based Measure (SMB and a super-efficiency (SE DEA, will be used in order to achieve an unambiguous ranking of the various regions or Decision Making Units (DMUs. The study will employ an extensive database on individual actors in the cluster, in combination with a broadly composed territorial-capital database for the areas under study. The paper will be concluded with some strategic policy lessons.

  6. The role of organic intertile layer in abalone nacre

    Energy Technology Data Exchange (ETDEWEB)

    Meyers, M.A., E-mail: mameyers@ucsd.edu [University of California, San Diego, La Jolla, California (United States); Lim, C.T.; Li, A.; Hairul Nizam, B.R.; Tan, E.P.S. [National University of Singapore, Singapore (Singapore); Seki, Y.; McKittrick, J. [University of California, San Diego, La Jolla, California (United States)

    2009-10-15

    Characterization of the growth surfaces removed from red and green abalone (Haliotis) shells shows a terraced cone mode of mineralization in which the organic layer is deposited periodically and regulates the formation of tiles with {approx} 500 nm thickness. The details of the mineral and organic layer surface are revealed by atomic force microscopy; the surface roughness and the thickness of the tiles in the terraces and organic intertile layer were measurement. Nanoindentation experiments at the top of the terraced cones confirm a hardness of the same order as that of completely mineralized surfaces. Indentation of the organic layer provides a force-deflection curve that can be expressed as tension on a centrally-loaded membrane. The results show that the dry organic layer is very stiff and deforms inelastically or cracks under the indenter, whereas in the fully hydrated state it shows a low modulus and strength and great extensibility. This strongly suggests that this organic interlayer acquires considerable strength and stiffness as a result of the drying process, which is consistent with a T{sub g} of approximately 200 deg. C for chitin. The chitin network that forms the structural component of the intertile layer is revealed and the orientation and spacing are measured. Terraced cones broken under the force of a flexing and shrinking organic layer enable the estimation of the tensile strength of the abalone when loaded through the fracture of the mineral bridges. Calculations show consistency with earlier tensile strength measurements of < 10 MPa.

  7. New Details of the Human Corneal Limbus Revealed With Second Harmonic Generation Imaging.

    Science.gov (United States)

    Park, Choul Yong; Lee, Jimmy K; Zhang, Cheng; Chuck, Roy S

    2015-09-01

    To report novel findings of the human corneal limbus by using second harmonic generation (SHG) imaging. Corneal limbus was imaged by using an inverted two-photon excitation fluorescence microscope. Laser (Ti:Sapphire) was tuned at 850 nm for two-photon excitation. Backscatter signals of SHG and autofluorescence (AF) were collected through a 425/30-nm emission filter and a 525/45-emission filter, respectively. Multiple, consecutive, and overlapping image stacks (z-stack) were acquired for the corneal limbal area. Two novel collagen structures were revealed by SHG imaging at the limbus: an anterior limbal cribriform layer and presumed anchoring fibers. Anterior limbal cribriform layer is an intertwined reticular collagen architecture just beneath the limbal epithelial niche and is located between the peripheral cornea and Tenon's/scleral tissue. Autofluorescence imaging revealed high vascularity in this structure. Central to the anterior limbal cribriform layer, radial strands of collagen were found to connect the peripheral cornea to the limbus. These presumed anchoring fibers have both collagen and elastin and were found more extensively in the superficial layers than deep layer and were absent in very deep limbus near Schlemm's canal. By using SHG imaging, new details of the collagen architecture of human corneal limbal area were elucidated. High resolution images with volumetric analysis revealed two novel collagen structures.

  8. Benthic boundary layer modelling studies

    International Nuclear Information System (INIS)

    Richards, K.J.

    1984-01-01

    A numerical model has been developed to study the factors which control the height of the benthic boundary layer in the deep ocean and the dispersion of a tracer within and directly above the layer. This report covers tracer clouds of horizontal scales of 10 to 100 km. The dispersion of a tracer has been studied in two ways. Firstly, a number of particles have been introduced into the flow. The trajectories of these particles provide information on dispersion rates. For flow conditions similar to those observed in the abyssal N.E. Atlantic the diffusivity of a tracer was found to be 5 x 10 6 cm 2 s -1 for a tracer within the boundary layer and 8 x 10 6 cm 2 s -1 for a tracer above the boundary layer. The results are in accord with estimates made from current meter measurements. The second method of studying dispersion was to calculate the evolution of individual tracer clouds. Clouds within and above the benthic boundary layer often show quite different behaviour from each other although the general structure of the clouds in the two regions were found to have no significant differences. (author)

  9. Elastic wave manipulation by using a phase-controlling meta-layer

    Science.gov (United States)

    Shen, Xiaohui; Sun, Chin-Teh; Barnhart, Miles V.; Huang, Guoliang

    2018-03-01

    In this work, a high pass meta-layer for elastic waves is proposed. An elastic phase-controlling meta-layer is theoretically realized using parallel and periodically arranged metamaterial sections based on the generalized Snell's law. The elastic meta-layer is composed of periodically repeated supercells, in which the frequency dependent elastic properties of the metamaterial are used to control a phase gradient at the interface between the meta-layer and conventional medium. It is analytically and numerically demonstrated that with a normal incident longitudinal wave, the wave propagation characteristics can be directly manipulated by the periodic length of the meta-layer element at the sub-wavelength scale. It is found that propagation of the incident wave through the interface is dependent on whether the working wavelength is longer or shorter than the periodic length of the meta-layer element. Specifically, a mode conversion of the P-wave to an SV-wave is investigated as the incident wave passes through the meta-layer region. Since the most common and damaging elastic waves in civil and mechanical industries are in the low frequency region, the work in this paper has great potential in the seismic shielding, engine vibration isolation, and other highly dynamic fields.

  10. Marine isoprene production and consumption in the mixed layer of the surface ocean - a field study over two oceanic regions

    Science.gov (United States)

    Booge, Dennis; Schlundt, Cathleen; Bracher, Astrid; Endres, Sonja; Zäncker, Birthe; Marandino, Christa A.

    2018-02-01

    Parameterizations of surface ocean isoprene concentrations are numerous, despite the lack of source/sink process understanding. Here we present isoprene and related field measurements in the mixed layer from the Indian Ocean and the eastern Pacific Ocean to investigate the production and consumption rates in two contrasting regions, namely oligotrophic open ocean and the coastal upwelling region. Our data show that the ability of different phytoplankton functional types (PFTs) to produce isoprene seems to be mainly influenced by light, ocean temperature, and salinity. Our field measurements also demonstrate that nutrient availability seems to have a direct influence on the isoprene production. With the help of pigment data, we calculate in-field isoprene production rates for different PFTs under varying biogeochemical and physical conditions. Using these new calculated production rates, we demonstrate that an additional significant and variable loss, besides a known chemical loss and a loss due to air-sea gas exchange, is needed to explain the measured isoprene concentration. We hypothesize that this loss, with a lifetime for isoprene between 10 and 100 days depending on the ocean region, is potentially due to degradation or consumption by bacteria.

  11. Monitoring Cu nodule formation using Ni marker layers

    Energy Technology Data Exchange (ETDEWEB)

    Lafouresse, M.C., E-mail: mlafouresse@gmail.co [Department of Civil and Earth Resources Engineering, Kyoto University, Katsura, Kyoto 615-8540 (Japan); Fukunaka, Y. [Institute for Nanoscience and Nanotechnology, Waseda University, Shinjuku Ku, Tokyo 169-8555 (Japan); ISS Science Project Office, JAXA, Tsukuba-shi, Ibaraki 305-8505 (Japan); Matsuoka, T. [Department of Civil and Earth Resources Engineering, Kyoto University, Katsura, Kyoto 615-8540 (Japan); Schwarzacher, W. [H. H. Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom)

    2011-04-30

    Highlights: {yields} Ni marker layers to monitor electrodeposited Cu nodule morphological evolution. {yields} The edges of the nodules trace out a straight line. {yields} Difference in growth between spheres and hemispheres. {yields} Nodule on nodule growth at high overpotential. {yields} No dramatic effect of the diffusion layer thickness on the film morphology. - Abstract: We have used Ni marker layers to study the evolution of the characteristic spheroidal nodule morphology in electrodeposited Cu films. Ultrathin Ni layers were electrodeposited in-between Cu layers, and cross sections prepared by electrochemical polishing. During growth of a typical spheroidal feature, the edge (i.e. where there is a discontinuity in the surface slope) traces out a straight line in the cross-sectional image. At high overpotential, the cross-sections show nodule-on-nodule growth, giving rise to the well known cauliflower morphology. Rotating disk electrode studies reveal that, surprisingly, the absolute diffusion layer thickness does not appear to play a major role in the development of spheres.

  12. Monitoring Cu nodule formation using Ni marker layers

    International Nuclear Information System (INIS)

    Lafouresse, M.C.; Fukunaka, Y.; Matsuoka, T.; Schwarzacher, W.

    2011-01-01

    Highlights: → Ni marker layers to monitor electrodeposited Cu nodule morphological evolution. → The edges of the nodules trace out a straight line. → Difference in growth between spheres and hemispheres. → Nodule on nodule growth at high overpotential. → No dramatic effect of the diffusion layer thickness on the film morphology. - Abstract: We have used Ni marker layers to study the evolution of the characteristic spheroidal nodule morphology in electrodeposited Cu films. Ultrathin Ni layers were electrodeposited in-between Cu layers, and cross sections prepared by electrochemical polishing. During growth of a typical spheroidal feature, the edge (i.e. where there is a discontinuity in the surface slope) traces out a straight line in the cross-sectional image. At high overpotential, the cross-sections show nodule-on-nodule growth, giving rise to the well known cauliflower morphology. Rotating disk electrode studies reveal that, surprisingly, the absolute diffusion layer thickness does not appear to play a major role in the development of spheres.

  13. Atomic layer deposition of epitaxial layers of anatase on strontium titanate single crystals: Morphological and photoelectrochemical characterization

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, Theodore J.; Nepomnyashchii, Alexander B.; Parkinson, B. A., E-mail: bparkin1@uwyo.edu [Department of Chemistry, School of Energy Resources, University of Wyoming, Laramie, Wyoming 82071 (United States)

    2015-01-15

    Atomic layer deposition was used to grow epitaxial layers of anatase (001) TiO{sub 2} on the surface of SrTiO{sub 3} (100) crystals with a 3% lattice mismatch. The epilayers grow as anatase (001) as confirmed by x-ray diffraction. Atomic force microscope images of deposited films showed epitaxial layer-by-layer growth up to about 10 nm, whereas thicker films, of up to 32 nm, revealed the formation of 2–5 nm anatase nanocrystallites oriented in the (001) direction. The anatase epilayers were used as substrates for dye sensitization. The as received strontium titanate crystal was not sensitized with a ruthenium-based dye (N3) or a thiacyanine dye (G15); however, photocurrent from excited state electron injection from these dyes was observed when adsorbed on the anatase epilayers. These results show that highly ordered anatase surfaces can be grown on an easily obtained substrate crystal.

  14. Synchrotron Topographic and Diffractometer Studies of Buried Layered Structures Obtained by Implantation with Swift Heavy Ions in Silicon Single Crystals

    International Nuclear Information System (INIS)

    Wierzchowski, W.; Wieteska, K.; Zymierska, D.; Graeff, W.; Czosnyka, T.; Choinski, J.

    2006-01-01

    A distribution of crystallographic defects and deformation in silicon crystals subjected to deep implantation (20-50 μm) with ions of the energy of a few MeV/amu is studied. Three different buried layered structures (single layer, binary buried structure and triple buried structure) were obtained by implantation of silicon single crystals with 184 MeV argon ions, 29.7 MeV boron ions, and 140 MeV argon ions, each implantation at a fluency of 1x10 14 ions cm -2 . The implanted samples were examined by means of white beam X-ray section and projection topography, monochromatic beam topography and by recording local rocking curves with the beam restricted to 50 x 50 μm 2 . The experiment pointed to a very low level of implantation-induced strain (below 10 -5 ). The white beam Bragg case section experiment revealed a layer producing district black contrast located at a depth of the expected mean ion range. The presence of these buried layered structures in studied silicon crystals strongly affected the fringe pattern caused by curvature of the samples. In case of white beam projection and monochromatic beam topographs the implanted areas were revealed as darker regions with a very tiny grain like structure. One may interpret these results as the effect of considerable heating causing annihilation of point defects and formation of dislocation loops connected with point defect clusters. (author)

  15. 137 Cs in the soil from Pljevlja region

    International Nuclear Information System (INIS)

    Vukotic, P.; Jovanovic, S.; Dapcevic, S.; Zic, J.

    1996-01-01

    Surface layer of the seven characteristic types of soil in Pljevlja region (Montenegro) is sampled. Soil samples are taken 33 locations, at eight of them from three layers up to 20 cm in depth. Specific activity of 137 Cs is then measured in the soil samples by a method of semiconductor gamma-spectrometry. Average cesium contamination in the region is found to be about 10 times higher than the same before Chernobyl accident. 137 Cs is still in the superficial soil layer, mostly to the depth of 10 cm. Contamination level of soil has certain regularities in distribution over the region, and is the highest on the two mutually almost parallel geographic directions. 7 refs.; 1 figs.; 1 tabs

  16. Layering Literacies and Contemporary Learning

    Science.gov (United States)

    Abrams, Sandra Schamroth; Russo, Michael P.

    2015-01-01

    This article explores how adolescents layer literacies in and outside school. Findings from a longitudinal study of gaming in a public library, as well as data related to the use of Portal 2 in a New York City middle school classroom, reveal how the students created, showcased, analyzed, and experimented with online and offline artifacts and…

  17. On hairpin vortices in a transitional boundary layer

    Directory of Open Access Journals (Sweden)

    Uruba Václav

    2012-04-01

    Full Text Available In the presented paper the results of experiments on transitional boundary layer are presented. The boundary layer was generated on smooth flat wall with zero pressure gradient forming one side of the channel of rectangular cross section. The hairpin vortices, packets of hairpin vortices, turbulent spots and calmed regions were experimentally investigated using time-resolved PIV technique.

  18. Investigation of epitaxial silicon layers as a material for radiation hardened silicon detectors

    International Nuclear Information System (INIS)

    Li, Z.; Eremin, V.; Ilyashenko, I.; Ivanov, A.; Verbitskaya, E.

    1997-12-01

    Epitaxial grown thick layers (≥ 100 micrometers) of high resistivity silicon (Epi-Si) have been investigated as a possible candidate of radiation hardened material for detectors for high-energy physics. As grown Epi-Si layers contain high concentration (up to 2 x 10 12 cm -3 ) of deep levels compared with that in standard high resistivity bulk Si. After irradiation of test diodes by protons (E p = 24 GeV) with a fluence of 1.5 x 10 11 cm -2 , no additional radiation induced deep traps have been detected. A reasonable explanation is that there is a sink of primary radiation induced defects (interstitial and vacancies), possibly by as-grown defects, in epitaxial layers. The ''sinking'' process, however, becomes non-effective at high radiation fluences (10 14 cm -2 ) due to saturation of epitaxial defects by high concentration of radiation induced ones. As a result, at neutron fluence of 1 x 10 14 cm -2 the deep level spectrum corresponds to well-known spectrum of radiation induced defects in high resistivity bulk Si. The net effective concentration in the space charge region equals to 3 x 10 12 cm -3 after 3 months of room temperature storage and reveals similar annealing behavior for epitaxial as compared to bulk silicon

  19. Modular representation of layered neural networks.

    Science.gov (United States)

    Watanabe, Chihiro; Hiramatsu, Kaoru; Kashino, Kunio

    2018-01-01

    Layered neural networks have greatly improved the performance of various applications including image processing, speech recognition, natural language processing, and bioinformatics. However, it is still difficult to discover or interpret knowledge from the inference provided by a layered neural network, since its internal representation has many nonlinear and complex parameters embedded in hierarchical layers. Therefore, it becomes important to establish a new methodology by which layered neural networks can be understood. In this paper, we propose a new method for extracting a global and simplified structure from a layered neural network. Based on network analysis, the proposed method detects communities or clusters of units with similar connection patterns. We show its effectiveness by applying it to three use cases. (1) Network decomposition: it can decompose a trained neural network into multiple small independent networks thus dividing the problem and reducing the computation time. (2) Training assessment: the appropriateness of a trained result with a given hyperparameter or randomly chosen initial parameters can be evaluated by using a modularity index. And (3) data analysis: in practical data it reveals the community structure in the input, hidden, and output layers, which serves as a clue for discovering knowledge from a trained neural network. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Preparation and characterization of self-assembled layer by layer NiCo2O4–reduced graphene oxide nanocomposite with improved electrocatalytic properties

    International Nuclear Information System (INIS)

    Srivastava, Manish; Elias Uddin, Md.; Singh, Jay; Kim, Nam Hoon; Lee, Joong Hee

    2014-01-01

    Graphical abstract: NiCo 2 O 4 were grown on RGO by in situ synthesis process. FE-SEM investigation revealed self assembled layer by layer growth of NiCo 2 O 4 –RGO nanocomposite. NiCo 2 O 4 –RGO nanocomposite exhibited synergetic effect of NiCo 2 O 4 nanoparticles and RGO on its electrochemical performance. -- Highlights: • NiCo 2 O 4 were grown on RGO by in-situ synthesis process. • FE-SEM image revealed self-assembled layer by layer growth of NiCo 2 O 4 -RGO nanocomposite. • NiCo 2 O 4 -RGO nanocomposite exhibited synergetic effects on its electrochemical performance. -- Abstract: NiCo 2 O 4 nanoparticles dispersed on reduced graphene oxide (RGO) are prepared by simultaneously reducing graphene oxide (GO), nickel and cobalt nitrate via a hydrothermal method assisted by post annealing at low temperature. The method involves formation of hydroxides on GO using ammonia under hydrothermal conditions. Subsequent thermal treatment at 300 °C led to the conversion of hydroxides into single-phase NiCo 2 O 4 atop the RGO. The synthesized products are characterized through several techniques including X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The FE-SEM investigations reveal the growth of a layer by layer assembly of NiCo 2 O 4 –RGO (2:1) nanocomposite, where the NiCo 2 O 4 nanoparticles are tightly packed between the layers of RGO. Further, the catalytic properties of the NiCo 2 O 4 –RGO nanocomposite are investigated for the oxygen evolution reaction (OER) through cyclic voltammetry (CV) measurements. It is observed that the special structural features of the NiCo 2 O 4 –RGO (2:1) nanocomposite, including layer by layer assembly, integrity and excellent dispersion of the NiCo 2 O 4 nanoparticles atop the RGO, produced

  1. Investigation of the Dissolution-Reformation Cycle of the Passive Oxide Layer on NiTi Orthodontic Archwires

    Science.gov (United States)

    Uzer, B.; Birer, O.; Canadinc, D.

    2017-09-01

    Dissolution-reformation cycle of the passive oxide layer on the nickel-titanium (NiTi) orthodontic archwires was investigated, which has recently been recognized as one of the key parameters dictating the biocompatibility of archwires. Specifically, commercially available NiTi orthodontic archwires were immersed in artificial saliva solutions of different pH values (2.3, 3.3, and 4.3) for four different immersion periods: 1, 7, 14, and 30 days. Characterization of the virgin and tested samples revealed that the titanium oxide layer on the NiTi archwire surfaces exhibit a dissolution-reformation cycle within the first 14 days of the immersion period: the largest amount of Ni ion release occurred within the first week of immersion, while it significantly decreased during the reformation period from day 7 to day 14. Furthermore, the oxide layer reformation was catalyzed on the grooves within the peaks and valleys due to relatively larger surface energy of these regions, which eventually decreased the surface roughness significantly within the reformation period. Overall, the current results clearly demonstrate that the analyses of dissolution-reformation cycle of the oxide layer in orthodontic archwires, surface roughness, and ion release behavior constitute utmost importance in order to ensure both the highest degree of biocompatibility and an efficient medical treatment.

  2. Genetic Structure and Demographic History Reveal Migration of the Diamondback Moth Plutella xylostella (Lepidoptera: Plutellidae) from the Southern to Northern Regions of China

    Science.gov (United States)

    Wei, Shu-Jun; Shi, Bao-Cai; Gong, Ya-Jun; Jin, Gui-Hua; Chen, Xue-Xin; Meng, Xiang-Feng

    2013-01-01

    The diamondback moth Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae) is one of the most destructive insect pests of cruciferous plants worldwide. Biological, ecological and genetic studies have indicated that this moth is migratory in many regions around the world. Although outbreaks of this pest occur annually in China and cause heavy damage, little is known concerning its migration. To better understand its migration pattern, we investigated the population genetic structure and demographic history of the diamondback moth by analyzing 27 geographical populations across China using four mitochondrial genes and nine microsatellite loci. The results showed that high haplotype diversity and low nucleotide diversity occurred in the diamondback moth populations, a finding that is typical for migratory species. No genetic differentiation among all populations and no correlation between genetic and geographical distance were found. However, pairwise analysis of the mitochondrial genes has indicated that populations from the southern region were more differentiated than those from the northern region. Gene flow analysis revealed that the effective number of migrants per generation into populations of the northern region is very high, whereas that into populations of the southern region is quite low. Neutrality testing, mismatch distribution and Bayesian Skyline Plot analyses based on mitochondrial genes all revealed that deviation from Hardy-Weinberg equilibrium and sudden expansion of the effective population size were present in populations from the northern region but not in those from the southern region. In conclusion, all our analyses strongly demonstrated that the diamondback moth migrates within China from the southern to northern regions with rare effective migration in the reverse direction. Our research provides a successful example of using population genetic approaches to resolve the seasonal migration of insects. PMID:23565158

  3. Active Pesticide Production Points, Region 9, 2013, US EPA Region 9

    Data.gov (United States)

    U.S. Environmental Protection Agency — This data layer represents Active Pesticide Producing Establishments in USEPA Region 9 (AZ, CA, HI and NV) that reported production for the year 2013. Pesticide...

  4. Direct numerical simulation of thermally-stratified turbulent boundary layer subjected to adverse pressure gradient

    International Nuclear Information System (INIS)

    Hattori, Hirofumi; Kono, Amane; Houra, Tomoya

    2016-01-01

    Highlights: • We study various thermally-stratified turbulent boundary layers having adverse pressure gradient (APG) by means of DNS. • The detailed turbulent statistics and structures in various thermally-stratified turbulent boundary layers having APG are discussed. • It is found that the friction coefficient and Stanton number decrease along the streamwise direction due to the effects of stable thermal stratification and APG, but those again increase due to the APG effect in the case of weak stable thermal stratification. • In the case of strong stable stratification with or without APG, the flow separation is observed in the downstream region. - Abstract: The objective of this study is to investigate and observe turbulent heat transfer structures and statistics in thermally-stratified turbulent boundary layers subjected to a non-equilibrium adverse pressure gradient (APG) by means of direct numerical simulation (DNS). DNSs are carried out under conditions of neutral, stable and unstable thermal stratifications with a non-equilibrium APG, in which DNS results reveal heat transfer characteristics of thermally-stratified non-equilibrium APG turbulent boundary layers. In cases of thermally-stratified turbulent boundary layers affected by APG, heat transfer performances increase in comparison with a turbulent boundary layer with neutral thermal stratification and zero pressure gradient (ZPG). Especially, it is found that the friction coefficient and Stanton number decrease along the streamwise direction due to the effects of stable thermal stratification and APG, but those again increase due to the APG effect in the case of weak stable thermal stratification (WSBL). Thus, the analysis for both the friction coefficient and Stanton number in the case of WSBL with/without APG is conducted using the FIK identity in order to investigate contributions from the transport equations, in which it is found that both Reynolds-shear-stress and the mean convection terms

  5. Characterizing permafrost active layer dynamics and sensitivity to landscape spatial heterogeneity in Alaska

    Science.gov (United States)

    Yi, Yonghong; Kimball, John S.; Chen, Richard H.; Moghaddam, Mahta; Reichle, Rolf H.; Mishra, Umakant; Zona, Donatella; Oechel, Walter C.

    2018-01-01

    An important feature of the Arctic is large spatial heterogeneity in active layer conditions, which is generally poorly represented by global models and can lead to large uncertainties in predicting regional ecosystem responses and climate feedbacks. In this study, we developed a spatially integrated modeling and analysis framework combining field observations, local-scale ( ˜ 50 m resolution) active layer thickness (ALT) and soil moisture maps derived from low-frequency (L + P-band) airborne radar measurements, and global satellite environmental observations to investigate the ALT sensitivity to recent climate trends and landscape heterogeneity in Alaska. Modeled ALT results show good correspondence with in situ measurements in higher-permafrost-probability (PP ≥ 70 %) areas (n = 33; R = 0.60; mean bias = 1.58 cm; RMSE = 20.32 cm), but with larger uncertainty in sporadic and discontinuous permafrost areas. The model results also reveal widespread ALT deepening since 2001, with smaller ALT increases in northern Alaska (mean trend = 0.32±1.18 cm yr-1) and much larger increases (> 3 cm yr-1) across interior and southern Alaska. The positive ALT trend coincides with regional warming and a longer snow-free season (R = 0.60 ± 0.32). A spatially integrated analysis of the radar retrievals and model sensitivity simulations demonstrated that uncertainty in the spatial and vertical distribution of soil organic carbon (SOC) was the largest factor affecting modeled ALT accuracy, while soil moisture played a secondary role. Potential improvements in characterizing SOC heterogeneity, including better spatial sampling of soil conditions and advances in remote sensing of SOC and soil moisture, will enable more accurate predictions of active layer conditions and refinement of the modeling framework across a larger domain.

  6. Process analysis of regional aerosol pollution during spring in the Pearl River Delta region, China

    Science.gov (United States)

    Fan, Qi; Lan, Jing; Liu, Yiming; Wang, Xuemei; Chan, Pakwai; Hong, Yingying; Feng, Yerong; Liu, Yexin; Zeng, Yanjun; Liang, Guixiong

    2015-12-01

    A numerical simulation analysis was performed for three air pollution episodes in the Pearl River Delta (PRD) region during March 2012 using the third-generation air quality modeling system Models-3/CMAQ. The results demonstrated that particulate matter was the primary pollutant for all three pollution episodes and was accompanied by relatively low visibility in the first two episodes. Weather maps indicate that the first two episodes occurred under the influence of warm, wet southerly air flow systems that led to high humidity throughout the region. The liquid phase reaction of gaseous pollutants resulted in the generation of fine secondary particles, which were identified as the primary source of pollution in the first two episodes. The third pollution episode occurred during a warming period following a cold front. Relative humidity was lower during this episode, and coarse particles were the major pollution contributor. Results of process analysis indicated that emissions sources, horizontal transport and vertical transport were the primary factors affecting pollutant concentrations within the near-surface layer during all three episodes, while aerosol processes, cloud processes, horizontal transport and vertical transport had greater influence at approximately 900 m above ground. Cloud processes had a greater impact during the first two pollution episodes because of the higher relative humidity. In addition, by comparing pollution processes from different cities (Guangzhou and Zhongshan), the study revealed that the first two pollution episodes were the result of local emissions within the PRD region and transport between surrounding cities, while the third episode exhibited prominent regional pollution characteristics and was the result of regional pollutant transport.

  7. NMR studies of the fifth transmembrane segment of Na+,K+-ATPase reveals a non-helical ion-binding region

    DEFF Research Database (Denmark)

    Underhaug, Jarl; Jakobsen, Louise Odgaard; Esmann, Mikael

    2006-01-01

    The structure of a synthetic peptide corresponding to the fifth membrane-spanning segment (M5) in Na(+),K(+)-ATPase in sodium dodecyl sulfate (SDS) micelles was determined using liquid-state nuclear magnetic resonance (NMR) spectroscopy. The spectra reveal that this peptide is substantially less...... transmembrane element of the Ca(2+)-ATPase. Furthermore, this region spans the residues implicated in Na(+) and K(+) transport, where they are likely to offer the flexibility needed to coordinate Na(+) as well as K(+) during active transport....... alpha-helical than the corresponding M5 peptide of Ca(2+)-ATPase. A well-defined alpha-helix is shown in the C-terminal half of the peptide. Apart from a short helical stretch at the N-terminus, the N-terminal half contains a non-helical region with two proline residues and sequence similarity to a non-structured...

  8. The role of annealing temperature variation on ZnO nanorods array deposited on TiO2 seed layer

    Science.gov (United States)

    Asib, N. A. M.; Aadila, A.; Afaah, A. N.; Rusop, M.; Khusaimi, Z.

    2018-05-01

    Seed layer of Titanium dioxide (TiO2) by sol-gel spin coating technique were coated on glass substrate to grow Zinc oxide nanorods (ZNR) by solution-immersion method. The fabricated ZNR were annealed at various temperatures ranged from 400 to 600° C. FESEM images revealed that smaller ZNR were densely grown at optimum temperature of 450 and 500°C. Meanwhile, for all samples a dominant (0 0 2) diffraction peak of ZNR recorded by XRD patterns was at 34.4° which corresponding to hexagonal ZNR with a wurtzite structure. UV-Vis absorbance spectra showed the maximum absorption properties at UV region were detected at 450 and 500°C. The samples also showed high absorbance values at visible region.

  9. Energetics and structure of the lower E region associated with sporadic E layer

    Directory of Open Access Journals (Sweden)

    K.-I. Oyama

    2008-09-01

    Full Text Available The electron temperature (Te, electron density (Ne, and two components of the electric field were measured from the height of 90 km to 150 km by one of the sounding rockets launched during the SEEK-2 campaign. The rocket went through sporadic E layer (Es at the height of 102 km–109 km during ascent and 99 km–108 km during decent, respectively. The energy density of thermal electrons calculated from Ne and Te shows the broad maximum in the height range of 100–110 km, and it decreases towards the lower and higher altitudes, which implies that a heat source exists in the height region of 100 km–110 km. A 3-D picture of Es, that was drawn by using Te, Ne, and the electric field data, corresponded to the computer simulation; the main structure of Es is projected to a higher altitude along the magnetic line of force, thus producing irregular structures of Te, Ne and electric field in higher altitude.

  10. Directed Vertical Diffusion of Photovoltaic Active Layer Components into Porous ZnO-Based Cathode Buffer Layers.

    Science.gov (United States)

    Kang, Jia-Jhen; Yang, Tsung-Yu; Lan, Yi-Kang; Wu, Wei-Ru; Su, Chun-Jen; Weng, Shih-Chang; Yamada, Norifumi L; Su, An-Chung; Jeng, U-Ser

    2018-04-01

    Cathode buffer layers (CBLs) can effectively further the efficiency of polymer solar cells (PSCs), after optimization of the active layer. Hidden between the active layer and cathode of the inverted PSC device configuration is the critical yet often unattended vertical diffusion of the active layer components across CBL. Here, a novel methodology of contrast variation with neutron and anomalous X-ray reflectivity to map the multicomponent depth compositions of inverted PSCs, covering from the active layer surface down to the bottom of the ZnO-based CBL, is developed. Uniquely revealed for a high-performance model PSC are the often overlooked porosity distributions of the ZnO-based CBL and the differential diffusions of the polymer PTB7-Th and fullerene derivative PC 71 BM of the active layer into the CBL. Interface modification of the ZnO-based CBL with fullerene derivative PCBEOH for size-selective nanochannels can selectively improve the diffusion of PC 71 BM more than that of the polymer. The deeper penetration of PC 71 BM establishes a gradient distribution of fullerene derivatives over the ZnO/PCBE-OH CBL, resulting in markedly improved electron mobility and device efficiency of the inverted PSC. The result suggests a new CBL design concept of progressive matching of the conduction bands. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Evaluation of the regional lung function revealed in radioaerosol scintigram of chronic obstructive pulmonary disease, 1

    International Nuclear Information System (INIS)

    Suzuki, Teruyasu

    1980-01-01

    We classified the findings of radioaerosol inhalation scintigrams of patients with various stages of obstructive pulmonary disease (COPD) into 4 grades, according to the extent of peripheral irregularity and central hot spot formation; Stage I represents normal homogeneous distribution, stage II represents peripheral irregularity, stage III represents additional hot spot formation and stage IV represents further regional defect. This aerosol grading criteria was then compared with routine and specific lung function tests. The aerosol grading criterion correlated well with FEV sub(1.0)% which is a good indicator of the severity of COPD. The central hot spot formation correlated well with FEV sub(1.0)% and respiratory resistance (R.p.) determined by the oscillation method, both of which are good indicators of abnormality in central airway resistance. Peripheral irregularity correlated well with: 1) flows at 50%VC and 25%VC in a maximum forced expiratory flow volume curve; 2) closing volume (CV/VC%); 3) delta N 2 %/l in N 2 single washout test; and 4) the regional delay of 133 Xe washout process, all of which are sensitive indicators of small airway disease. It is therefore reasonable to conclude that the radioaerosol scintigram reveals the regional lung function both in terms of airway resistance (R) and compliance (C). This criterion was useful in quantitatively evaluating the regional ventilation distribution of COPD and the therapeutic effect on bronchial asthma. The mechanism of aerosol praticle deposition related to characteristic central hot spot formation accompanied with peripheral irregularity in a radioaerosol scintigram of COPD, needs further exploration concerning the aerodynamic behavior of aerosol particles in the airways both during inspiration and expiration. (author)

  12. Density Functional Theory Calculations Revealing Metal-like Band Structures for Ultrathin Ge {111} and {211} Surface Layers.

    Science.gov (United States)

    Tan, Chih-Shan; Huang, Michael Hsuan-Yi

    2018-05-21

    To find out if germanium should also possess facet-dependent electrical conductivity properties, surface state density functional theory (DFT) calculations were performed on 1-6 layers of Ge (100), (110), (111), and (211) planes. Tunable Ge (100) and (110) planes always present the same semiconducting band structure with a band gap of 0.67 eV expected of bulk germanium. In contrast, 1, 2, 4, and 5 layers of Ge (111) and (211) plane models show metal-like band structures with continuous density of states (DOS) throughout the entire band. For 3 and 6 layers of Ge (111) and (211) plane models, the normal semiconducting band structure was obtained. The plane layers with metal-like band structures also show Ge-Ge bond length deviations and bond distortions, as well as significantly different 4s and 4p frontier orbital electron count and their relative percentages integrated over the valence and conduction bands from those of the semiconducting state. These differences should contribute to strikingly dissimilar band structures. The calculation results suggest observation of facet-dependent electrical conductivity properties of germanium materials, and transistors made of germanium may also need to consider the facet effects with shrinking dimensions approaching 3 nm. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Third-order susceptibility of gold for ultrathin layers

    DEFF Research Database (Denmark)

    Lysenko, Oleg; Bache, Morten; Lavrinenko, Andrei

    2016-01-01

    This Letter presents an experimental study of nonlinear plasmonic effects in gold-stripe waveguides. The optical characterization is performed by a picosecond laser and reveals two nonlinear effects related to propagation of long-range surface plasmon polaritons: nonlinear power transmission...... of plasmonic modes and spectral broadening of plasmonic modes. The experimental values of the third-order susceptibility of the gold layers are extracted. They exhibit a clear dependence on layer thickness. (C) 2016 Optical Society of America...

  14. Diffusive boundary layers over varying topography

    KAUST Repository

    Dell, R. W.

    2015-03-25

    Diffusive bottom boundary layers can produce upslope flows in a stratified fluid. Accumulating observations suggest that these boundary layers may drive upwelling and mixing in mid-ocean ridge flank canyons. However, most studies of diffusive bottom boundary layers to date have concentrated on constant bottom slopes. We present a study of how diffusive boundary layers interact with various idealized topography, such as changes in bottom slope, slopes with corrugations and isolated sills. We use linear theory and numerical simulations in the regional ocean modeling system (ROMS) model to show changes in bottom slope can cause convergences and divergences within the boundary layer, in turn causing fluid exchanges that reach far into the overlying fluid and alter stratification far from the bottom. We also identify several different regimes of boundary-layer behaviour for topography with oceanographically relevant size and shape, including reversing flows and overflows, and we develop a simple theory that predicts the regime boundaries, including what topographies will generate overflows. As observations also suggest there may be overflows in deep canyons where the flow passes over isolated bumps and sills, this parameter range may be particularly significant for understanding the role of boundary layers in the deep ocean.

  15. Mapping of PARK2 and PACRG overlapping regulatory region reveals LD structure and functional variants in association with leprosy in unrelated indian population groups.

    Science.gov (United States)

    Chopra, Rupali; Ali, Shafat; Srivastava, Amit K; Aggarwal, Shweta; Kumar, Bhupender; Manvati, Siddharth; Kalaiarasan, Ponnusamy; Jena, Mamta; Garg, Vijay K; Bhattacharya, Sambit N; Bamezai, Rameshwar N K

    2013-01-01

    Leprosy is a chronic infectious disease caused by Mycobacterium Leprae, where the host genetic background plays an important role toward the disease pathogenesis. Various studies have identified a number of human genes in association with leprosy or its clinical forms. However, non-replication of results has hinted at the heterogeneity among associations between different population groups, which could be due to differently evolved LD structures and differential frequencies of SNPs within the studied regions of the genome. A need for systematic and saturated mapping of the associated regions with the disease is warranted to unravel the observed heterogeneity in different populations. Mapping of the PARK2 and PACRG gene regulatory region with 96 SNPs, with a resolution of 1 SNP per 1 Kb for PARK2 gene regulatory region in a North Indian population, showed an involvement of 11 SNPs in determining the susceptibility towards leprosy. The association was replicated in a geographically distinct and unrelated population from Orissa in eastern India. In vitro reporter assays revealed that the two significantly associated SNPs, located 63.8 kb upstream of PARK2 gene and represented in a single BIN of 8 SNPs, influenced the gene expression. A comparison of BINs between Indian and Vietnamese populations revealed differences in the BIN structures, explaining the heterogeneity and also the reason for non-replication of the associated genomic region in different populations.

  16. Radioluminescent nuclear batteries with different phosphor layers

    International Nuclear Information System (INIS)

    Hong, Liang; Tang, Xiao-Bin; Xu, Zhi-Heng; Liu, Yun-Peng; Chen, Da

    2014-01-01

    Highlights: • We present and test the electrical properties of the nuclear battery. • The best thickness range for ZnS:Cu phosphor layer is 12–14 mg cm −2 for 147 Pm radioisotope. • The best thickness range for Y 2 O 2 S:Eu phosphor layer is 17–21 mg cm −2147 Pm radioisotope. • The battery with ZnS:Cu phosphor layer can provide higher energy conversion efficiency. • The mechanism affecting the nuclear battery output performance is revealed. - Abstract: A radioluminescent nuclear battery based on the beta radioluminescence of phosphors is presented, and which consists of 147 Pm radioisotope, phosphor layers, and GaAs photovoltaic cell. ZnS:Cu and Y 2 O 2 S:Eu phosphor layers for various thickness were fabricated. To investigate the effect of phosphor layer parameters on the battery, the electrical properties were measured. Results indicate that the optimal thickness ranges for the ZnS:Cu and Y 2 O 2 S:Eu phosphor layers are 12 mg cm −2 to 14 mg cm −2 and 17 mg cm −2 to 21 mg cm −2 , respectively. ZnS:Cu phosphor layer exhibits higher fluorescence efficiency compared with the Y 2 O 2 S:Eu phosphor layer. Its spectrum properly matches the spectral response of GaAs photovoltaic cell. As a result, the battery with ZnS:Cu phosphor layer indicates higher energy conversion efficiency than that with Y 2 O 2 S:Eu phosphor layer. Additionally, the mechanism of the phosphor layer parameters that influence the output performance of the battery is discussed through the Monte Carlo method and transmissivity test

  17. Covalent assembly of poly(ethyleneimine) via layer-by-layer deposition for enhancing surface density of protein and bacteria attachment

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Bing, E-mail: xiabing@njfu.edu.cn [Key Laboratory of Forest Genetics and Biotechnology (Ministry of Education of China), Nanjing Forestry University, Nanjing 210037 (China); Advanced Analysis and Testing Center, Nanjing Forestry University, Nanjing 210037 (China); Shi, Jisen; Dong, Chen; Zhang, Wenyi; Lu, Ye [Key Laboratory of Forest Genetics and Biotechnology (Ministry of Education of China), Nanjing Forestry University, Nanjing 210037 (China); Guo, Ping [Nanjing College of Information Technology, Nanjing 210023 (China)

    2014-02-15

    Covalently assembly of low molecular weight poly(ethyleneimine) was introduced to glass surfaces via glutaraldehyde crosslinking, with focus on its application on protein immobilization or bacteria attachment. Characterizations of Fourier transform infrared spectroscopy and ellipsometry measurement revealed a stepwise growth of poly(ethyleneimine) films by layer-by-layer deposition. After fluorescein isothiocyanate labelling, photoluminescence spectroscopy measurement indicated that the amount of surface accessible amine groups had been gradually enhanced with increasing poly(ethyleneimine) layers deposition. As compared with traditional aminosilanized surfaces, the surface density of amine groups was enhanced by ∼11 times after five layers grafting, which resulted in ∼9-time increasing of surface density of immobilized bovine serum albumin. Finally, these as-prepared PEI multi-films with excellent biocompatibility were adopted as culture substrates to improve Escherichia coli adherence, which showed that their surface density had been increased by ∼251 times.

  18. Investigation of switching region in superlattice phase change memories

    Science.gov (United States)

    Ohyanagi, T.; Takaura, N.

    2016-10-01

    We investigated superlattice phase change memories (PCMs) to clarify which regions were responsible for switching. We observed atomic structures in a superlattice PCM film with a stack of GeTe / Sb2Te3 layers using atomically resolved EDX maps, and we found an intermixed region with three atom species of the Ge, Sb and Te around the top GeTe layer under the top electrode. We also found that a device with a GeTe layer on an Sb2Te3 layer without superlattice structure had the same switching characteristics as a device with a superlattice PCM, that had the same top GeTe layer. We developed and fabricated a modified superlattice PCM that attained ultra low Reset / Set currents under 60 μ A .

  19. Boundary layers of the earth's outer magnetosphere

    Science.gov (United States)

    Eastman, T. E.; Frank, L. A.

    1984-01-01

    The magnetospheric boundary layer and the plasma-sheet boundary layer are the primary boundary layers of the earth's outer magnetosphere. Recent satellite observations indicate that they provide for more than 50 percent of the plasma and energy transport in the outer magnetosphere although they constitute less than 5 percent by volume. Relative to the energy density in the source regions, plasma in the magnetospheric boundary layer is predominantly deenergized whereas plasma in the plasma-sheet boundary layer has been accelerated. The reconnection hypothesis continues to provide a useful framework for comparing data sampled in the highly dynamic magnetospheric environment. Observations of 'flux transfer events' and other detailed features near the boundaries have been recently interpreted in terms of nonsteady-state reconnection. Alternative hypotheses are also being investigated. More work needs to be done, both in theory and observation, to determine whether reconnection actually occurs in the magnetosphere and, if so, whether it is important for overall magnetospheric dynamics.

  20. Boundary layers of the earth's outer magnetosphere

    International Nuclear Information System (INIS)

    Eastman, T.E.; Frank, L.A.

    1984-01-01

    The magnetospheric boundary layer and the plasma-sheet boundary layer are the primary boundary layers of the earth's outer magnetosphere. Recent satellite observations indicate that they provide for more than 50 percent of the plasma and energy transport in the outer magnetosphere although they constitute less than 5 percent by volume. Relative to the energy density in the source regions, plasma in the magnetospheric boundary layer is predominantly deenergized whereas plasma in the plasma-sheet boundary layer has been accelerated. The reconnection hypothesis continues to provide a useful framework for comparing data sampled in the highly dynamic magnetospheric environment. Observations of flux transfer events and other detailed features near the boundaries have been recently interpreted in terms of nonsteady-state reconnection. Alternative hypotheses are also being investigated. More work needs to be done, both in theory and observation, to determine whether reconnection actually occurs in the magnetosphere and, if so, whether it is important for overall magnetospheric dynamics. 30 references

  1. Global MYCN transcription factor binding analysis in neuroblastoma reveals association with distinct E-box motifs and regions of DNA hypermethylation.

    LENUS (Irish Health Repository)

    Murphy, Derek M

    2009-01-01

    BACKGROUND: Neuroblastoma, a cancer derived from precursor cells of the sympathetic nervous system, is a major cause of childhood cancer related deaths. The single most important prognostic indicator of poor clinical outcome in this disease is genomic amplification of MYCN, a member of a family of oncogenic transcription factors. METHODOLOGY: We applied MYCN chromatin immunoprecipitation to microarrays (ChIP-chip) using MYCN amplified\\/non-amplified cell lines as well as a conditional knockdown cell line to determine the distribution of MYCN binding sites within all annotated promoter regions. CONCLUSION: Assessment of E-box usage within consistently positive MYCN binding sites revealed a predominance for the CATGTG motif (p<0.0016), with significant enrichment of additional motifs CATTTG, CATCTG, CAACTG in the MYCN amplified state. For cell lines over-expressing MYCN, gene ontology analysis revealed enrichment for the binding of MYCN at promoter regions of numerous molecular functional groups including DNA helicases and mRNA transcriptional regulation. In order to evaluate MYCN binding with respect to other genomic features, we determined the methylation status of all annotated CpG islands and promoter sequences using methylated DNA immunoprecipitation (MeDIP). The integration of MYCN ChIP-chip and MeDIP data revealed a highly significant positive correlation between MYCN binding and DNA hypermethylation. This association was also detected in regions of hemizygous loss, indicating that the observed association occurs on the same homologue. In summary, these findings suggest that MYCN binding occurs more commonly at CATGTG as opposed to the classic CACGTG E-box motif, and that disease associated over expression of MYCN leads to aberrant binding to additional weaker affinity E-box motifs in neuroblastoma. The co-localization of MYCN binding and DNA hypermethylation further supports the dual role of MYCN, namely that of a classical transcription factor affecting the

  2. Effect of Mg doping in ZnO buffer layer on ZnO thin film devices for electronic applications

    Science.gov (United States)

    Giri, Pushpa; Chakrabarti, P.

    2016-05-01

    Zinc Oxide (ZnO) thin films have been grown on p-silicon (Si) substrate using magnesium doped ZnO (Mg: ZnO) buffer layer by radio-frequency (RF) sputtering method. In this paper, we have optimized the concentration of Mg (0-5 atomic percent (at. %)) ZnO buffer layer to examine its effect on ZnO thin film based devices for electronic and optoelectronic applications. The crystalline nature, morphology and topography of the surface of the thin film have been characterized. The optical as well as electrical properties of the active ZnO film can be tailored by varying the concentration of Mg in the buffer layer. The crystallite size in the active ZnO thin film was found to increase with the Mg concentration in the buffer layer in the range of 0-3 at. % and subsequently decrease with increasing Mg atom concentration in the ZnO. The same was verified by the surface morphology and topography studies carried out with scanning electron microscope (SEM) and atomic electron microscopy (AFM) respectively. The reflectance in the visible region was measured to be less than 80% and found to decrease with increase in Mg concentration from 0 to 3 at. % in the buffer region. The optical bandgap was initially found to increase from 3.02 eV to 3.74 eV by increasing the Mg content from 0 to 3 at. % but subsequently decreases and drops down to 3.43 eV for a concentration of 5 at. %. The study of an Au:Pd/ZnO Schottky diode reveals that for optimum doping of the buffer layer the device exhibits superior rectifying behavior. The barrier height, ideality factor, rectification ratio, reverse saturation current and series resistance of the Schottky diode were extracted from the measured current voltage (I-V) characteristics.

  3. Multi-type particle layer improved light trapping for photovoltaic applications

    DEFF Research Database (Denmark)

    David, Christin

    2016-01-01

    . The absorbance was enhanced compared to the bare Si wafer and I demonstrated on mixing particles a broadband boost in the absorbance within the homogeneous wafer region, excluding parasitic absorption in the particle layer. I studied the efficiency enhancement for varying geometries. Multi-type layers made of Si...

  4. Formation and properties of the buried isolating silicon-dioxide layer in double-layer “porous silicon-on-insulator” structures

    Energy Technology Data Exchange (ETDEWEB)

    Bolotov, V. V.; Knyazev, E. V.; Ponomareva, I. V.; Kan, V. E., E-mail: kan@obisp.oscsbras.ru; Davletkildeev, N. A.; Ivlev, K. E.; Roslikov, V. E. [Russian Academy of Sciences, Omsk Scientific Center, Siberian Branch (Russian Federation)

    2017-01-15

    The oxidation of mesoporous silicon in a double-layer “macroporous silicon–mesoporous silicon” structure is studied. The morphology and dielectric properties of the buried insulating layer are investigated using electron microscopy, ellipsometry, and electrical measurements. Specific defects (so-called spikes) are revealed between the oxidized macropore walls in macroporous silicon and the oxidation crossing fronts in mesoporous silicon. It is found that, at an initial porosity of mesoporous silicon of 60%, three-stage thermal oxidation leads to the formation of buried silicon-dioxide layers with an electric-field breakdown strength of E{sub br} ~ 10{sup 4}–10{sup 5} V/cm. Multilayered “porous silicon-on-insulator” structures are shown to be promising for integrated chemical micro- and nanosensors.

  5. Chitosan Derivatives/Calcium Carbonate Composite Capsules Prepared by the Layer-by-Layer Deposition Method

    Directory of Open Access Journals (Sweden)

    Takashi Sasaki

    2008-01-01

    Full Text Available Core/shell capsules composed of calcium carbonate whisker core (rod-like shape and chitosan/chitosansulfate shell were prepared by the layer-by-layer deposition technique. Two chitosan samples of different molecular weights (Mw=9.7×104 and 1.09×106g·mol-1 were used as original materials. Hollow capsules were also obtained by dissolution of the core in hydrochloric acid. Electron microscopy revealed that the surface of the shell is rather ragged associated with some agglomerates. The shell thickness l obeys a linear relation with respect to the number of deposited layers m as l=md+a(a>0. The values of d (thickness per layer were 4.0 and 1.0 nm for the higher and lower Mw chitosan materials, respectively, both of which are greater than the thickness of the monolayer. The results suggest that the feature of the deposition does not obey an ideal homogeneous monolayer-by-monolayer deposition mechanism. Shell crosslinked capsules were also prepared via photodimerization reaction of cinnamoyl groups after a deposition of cinnamoyl chitosan to the calcium carbonate whisker core. The degree of crosslink was not enough to stabilize the shell structure, and hollow capsule was not obtained.

  6. Self-assembled Nano-layering at the Adhesive interface.

    Science.gov (United States)

    Yoshida, Y; Yoshihara, K; Nagaoka, N; Hayakawa, S; Torii, Y; Ogawa, T; Osaka, A; Meerbeek, B Van

    2012-04-01

    According to the 'Adhesion-Decalcification' concept, specific functional monomers within dental adhesives can ionically interact with hydroxyapatite (HAp). Such ionic bonding has been demonstrated for 10-methacryloyloxydecyl dihydrogen phosphate (MDP) to manifest in the form of self-assembled 'nano-layering'. However, it remained to be explored if such nano-layering also occurs on tooth tissue when commercial MDP-containing adhesives (Clearfil SE Bond, Kuraray; Scotchbond Universal, 3M ESPE) were applied following common clinical application protocols. We therefore characterized adhesive-dentin interfaces chemically, using x-ray diffraction (XRD) and energy-dispersive x-ray spectroscopy (EDS), and ultrastructurally, using (scanning) transmission electron microscopy (TEM/STEM). Both adhesives revealed nano-layering at the adhesive interface, not only within the hybrid layer but also, particularly for Clearfil SE Bond (Kuraray), extending into the adhesive layer. Since such self-assembled nano-layering of two 10-MDP molecules, joined by stable MDP-Ca salt formation, must make the adhesive interface more resistant to biodegradation, it may well explain the documented favorable clinical longevity of bonds produced by 10-MDP-based adhesives.

  7. Ex-vivo diffusion MRI reveals microstructural alterations in stress-sensitive brain regions: A chronic mild stress recovery study

    DEFF Research Database (Denmark)

    Khan, Ahmad Raza; Hansen, Brian; Wiborg, Ove

    Depression is a leading cause of disability worldwide and causes significant microstructural alterations in stress-sensitive brain regions. However, the potential recovery of these microstructural alterations has not previously been investigated, which we, therefore, set out to do using diffusion...... MRI (d-MRI) in the chronic mild stress (CMS) rat model of depression. This study reveals significant microstructural alterations after 8 weeks of recovery, in the opposite direction to change induced by stress in the acute phase of the experiment. Such findings may be useful in the prognosis...... of depression or for monitoring treatment response....

  8. Spectral properties of porphyrins in the systems with layered silicates

    International Nuclear Information System (INIS)

    Ceklovsky, A.

    2009-03-01

    This work is focused on investigation of hybrid materials based on layered silicates, representing host inorganic component, and porphyrin dyes as organic guest. Aqueous colloidal dispersions, as well as thin solid films of layered silicate/porphyrin systems were studied. Modification of photophysical properties, such as absorption and fluorescence of molecules, adsorbed or incorporated in layered silicate hosts, were studied mainly to spread the knowledge about the environments suitable for incorporating aromatic compounds, providing photoactive properties of potential technological interest. TMPyP cations interact with the surfaces of layered silicates via electrostatic interactions. The extent of dye adsorption on colloidal particles of the silicates is influenced by the CEC values and swelling ability of silicates. Interaction of porphyrins with layered silicate hosts leads to significant changes of dye spectral properties. One of the key parameters that has a crucial impact on this interaction is the layer charge of silicate template. Other factors influence the resulting spectral properties of hybrid systems, such as the method of hybrid material preparation, the material's type (colloid, film), and the modification of the silicate host. Molecular orientation studies using linearly-polarized spectroscopies in VIS and IR regions revealed that TMPyP molecules were oriented in almost parallel fashion with respect to the silicate surface plane. Slightly higher values of the orientation angle of TMPyP transition moment were observed for the TMPyP/FHT system. Thus, flattening of the guest TMPyP molecules is the next important factor (mainly in the systems with lower layer charge), influencing its spectral properties upon the interaction with layered silicates. Fluorescence was effectively quenched in the systems based on solid films prepared from the high concentration of the dye (10-3 mol.dm-3). The quenching is most probably related to the structure of the

  9. Nonsingular walls in plane cholesteric layers

    International Nuclear Information System (INIS)

    Belyakov, V A; Osipov, M A; Stewart, I W

    2006-01-01

    The structure of a straight interface (wall) between regions with differing values of the pitch in planar cholesteric layers with finite strength of the surface anchoring is investigated theoretically. It is found that the shape and strength of the anchoring potential influences essentially the structure of the wall and a motionless wall between thermodynamically stable regions without a singularity in the director distribution in the layer can exist for sufficiently weak anchoring only. More specifically, for the existence of such a wall the dimensionless parameter S d = K 22 /Wd (where W is the depth of the anchoring potential, K 22 is the elastic twist modulus and d is the layer thickness) should exceed its critical value, which is dependent on the shape of the anchoring potential. General equations describing the director distribution in the wall are presented. Detailed analysis of these equations is carried out for the case of infinitely strong anchoring at one surface and finite anchoring strength at the second layer surface. It is shown that the wall width L is directly dependent upon the shape and strength of the anchoring potential and that its estimate ranges from d to (dL p ) 1/2 (where L p = K 22 /W is the penetration length), corresponding to different anchoring strengths and shape potentials. The dependence of the director distribution in the wall upon all three Frank elastic moduli is analytically found for some specific limiting cases of the model anchoring potentials. Motion of the wall is briefly investigated and the corresponding calculations performed under the assumption that the shape of a moving wall is the same as a motionless one. It is noted that experimental investigation of the walls in planar cholesteric layers can be used for the determination of the actual shape of surface anchoring potentials

  10. High-Sensitive Two-Layer Photoresistors Based on p-Cd x Hg1-x Te with a Converted Near-Surface Layer

    Science.gov (United States)

    Ismailov, N. D.; Talipov, N. Kh.; Voitsekhovskii, A. V.

    2018-04-01

    The results of an experimental study of photoelectric characteristics of two-layer photoresistors based on p-Cd x Hg1-x Te (x = 0.24-0.28) with a thin near-surface layer of n-type obtained by treatment in atmospheric gas plasma are presented. It is shown that the presence of a potential barrier between the p- and n-regions causes high photosensitivity and speed of operation of such photoresistors at T = 77 K

  11. High-Sensitive Two-Layer Photoresistors Based on p-Cd x Hg1- x Te with a Converted Near-Surface Layer

    Science.gov (United States)

    Ismailov, N. D.; Talipov, N. Kh.; Voitsekhovskii, A. V.

    2018-04-01

    The results of an experimental study of photoelectric characteristics of two-layer photoresistors based on p-Cd x Hg1- x Te (x = 0.24-0.28) with a thin near-surface layer of n-type obtained by treatment in atmospheric gas plasma are presented. It is shown that the presence of a potential barrier between the p- and n-regions causes high photosensitivity and speed of operation of such photoresistors at T = 77 K

  12. Natural convection flow and heat transfer between a fluid layer and a porous layer inside a rectangular enclosure

    International Nuclear Information System (INIS)

    Beckermann, C.; Ramadhyani, S.; Viskanta, R.

    1986-01-01

    A numerical and experimental study is performed to analyze the steady-state natural convection fluid flow and heat transfer in a vertical rectangular enclosure that is partially filled with a vertical layer of a fluid-saturated porous medium. The flow in the porous layer is modeled utilizing the Brinkman-Forchheimer-extended Darcy equations. The numerical model is verified by conducting a number of experiments with spherical glass beads as the porous medium and water and glycerin as the fluids in rectangular test-cells. The agreement between the flow visualization results and temperature measurements and the numerical model is, in general, good. It is found that the amount of fluid penetrating from the fluid region into the porous layer depends strongly on the Darcy (Da) and Rayleigh (Ra) numbers. For a relatively low product of Ra x Da, the flow takes place primarily in the fluid layer, and heat transfer in the porous layer is by conduction only. On the other hand, fluid penetrating into a relatively highly permeable porous layer has a significant impact on the natural convection flow patterns in the entire enclosure

  13. Turbulent/non-turbulent interfaces detected in DNS of incompressible turbulent boundary layers

    Science.gov (United States)

    Watanabe, T.; Zhang, X.; Nagata, K.

    2018-03-01

    The turbulent/non-turbulent interface (TNTI) detected in direct numerical simulations is studied for incompressible, temporally developing turbulent boundary layers at momentum thickness Reynolds number Reθ ≈ 2000. The outer edge of the TNTI layer is detected as an isosurface of the vorticity magnitude with the threshold determined with the dependence of the turbulent volume on a threshold level. The spanwise vorticity magnitude and passive scalar are shown to be good markers of turbulent fluids, where the conditional statistics on a distance from the outer edge of the TNTI layer are almost identical to the ones obtained with the vorticity magnitude. Significant differences are observed for the conditional statistics between the TNTI detected by the kinetic energy and vorticity magnitude. A widely used grid setting determined solely from the wall unit results in an insufficient resolution in a streamwise direction in the outer region, whose influence is found for the geometry of the TNTI and vorticity jump across the TNTI layer. The present results suggest that the grid spacing should be similar for the streamwise and spanwise directions. Comparison of the TNTI layer among different flows requires appropriate normalization of the conditional statistics. Reference quantities of the turbulence near the TNTI layer are obtained with the average of turbulent fluids in the intermittent region. The conditional statistics normalized by the reference turbulence characteristics show good quantitative agreement for the turbulent boundary layer and planar jet when they are plotted against the distance from the outer edge of the TNTI layer divided by the Kolmogorov scale defined for turbulent fluids in the intermittent region.

  14. Massive CO2 Ice Deposits Sequestered in the South Polar Layered Deposits of Mars

    Science.gov (United States)

    Phillips, Roger J.; Davis, Brian J.; Tanaka, Kenneth L.; Byrne, Shane; Mellon, Michael T.; Putzig, Nathaniel E.; Haberle, Robert M.; Kahre, Melinda A.; Campbell, Bruce A.; Carter, Lynn M.; Smith, Isaac B.; Holt, John W.; Smrekar, Suzanne E.; Nunes, Daniel C.; Plaut, Jeffrey J.; Egan, Anthony F.; Titus, Timothy N.; Seu, Roberto

    2011-01-01

    Shallow Radar soundings from the Mars Reconnaissance Orbiter reveal a buried deposit of carbon dioxide (CO2) ice within the south polar layered deposits of Mars with a volume of 9500 to 12,500 cubic kilometers, about 30 times that previously estimated for the south pole residual cap. The deposit occurs within a stratigraphic unit that is uniquely marked by collapse features and other evidence of interior CO2 volatile release. If released into the atmosphere at times of high obliquity, the CO2 reservoir would increase the atmospheric mass by up to 80%, leading to more frequent and intense dust storms and to more regions where liquid water could persist without boiling.

  15. Effect of cooler electrons on a compressive ion acoustic solitary wave in a warm ion plasma — Forbidden regions, double layers, and supersolitons

    International Nuclear Information System (INIS)

    Ghosh, S. S.; Sekar Iyengar, A. N.

    2014-01-01

    It is observed that the presence of a minority component of cooler electrons in a three component plasma plays a deterministic role in the evolution of solitary waves, double layers, or the newly discovered structures called supersolitons. The inclusion of the cooler component of electrons in a single electron plasma produces sharp increase in nonlinearity in spite of a decrease in the overall energy of the system. The effect maximizes at certain critical value of the number density of the cooler component (typically 15%–20%) giving rise to a hump in the amplitude variation profile. For larger amplitudes, the hump leads to a forbidden region in the ambient cooler electron concentration which dissociates the overall existence domain of solitary wave solutions in two distinct parameter regime. It is observed that an inclusion of the cooler component of electrons as low as < 1% affects the plasma system significantly resulting in compressive double layers. The solution is further affected by the cold to hot electron temperature ratio. In an adequately hotter bulk plasma (i.e., moderately low cold to hot electron temperature ratio), the parameter domain of compressive double layers is bounded by a sharp discontinuity in the corresponding amplitude variation profile which may lead to supersolitons

  16. Effect of cooler electrons on a compressive ion acoustic solitary wave in a warm ion plasma — Forbidden regions, double layers, and supersolitons

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, S. S., E-mail: sukti@iigs.iigm.res.in [Indian Institute of Geomagnetism, New Panvel, Navi Mumbai 410218 (India); Sekar Iyengar, A. N. [Plasma Physics Division, Saha Institute of Nuclear Physics, Kolkata 700064 (India)

    2014-08-15

    It is observed that the presence of a minority component of cooler electrons in a three component plasma plays a deterministic role in the evolution of solitary waves, double layers, or the newly discovered structures called supersolitons. The inclusion of the cooler component of electrons in a single electron plasma produces sharp increase in nonlinearity in spite of a decrease in the overall energy of the system. The effect maximizes at certain critical value of the number density of the cooler component (typically 15%–20%) giving rise to a hump in the amplitude variation profile. For larger amplitudes, the hump leads to a forbidden region in the ambient cooler electron concentration which dissociates the overall existence domain of solitary wave solutions in two distinct parameter regime. It is observed that an inclusion of the cooler component of electrons as low as < 1% affects the plasma system significantly resulting in compressive double layers. The solution is further affected by the cold to hot electron temperature ratio. In an adequately hotter bulk plasma (i.e., moderately low cold to hot electron temperature ratio), the parameter domain of compressive double layers is bounded by a sharp discontinuity in the corresponding amplitude variation profile which may lead to supersolitons.

  17. Influence of the density of placement on the stability of armour layers on breakwaters

    NARCIS (Netherlands)

    Van den Bosch, A.; D' Angremond, K.; Verhagen, H.J.; Olthof, J.

    2002-01-01

    Studies on the stability of the amour layer (d’Angremond et. al. [1999] revealed the importance of density of placement. The current research focuses on the influence of the density of placement on the stability of cubes in a double armour layer and tetrapods and rocks in a single armour layer. The

  18. Effect of oxide insertion layer on resistance switching properties of copper phthalocyanine

    Science.gov (United States)

    Joshi, Nikhil G.; Pandya, Nirav C.; Joshi, U. S.

    2013-02-01

    Organic memory device showing resistance switching properties is a next-generation of the electrical memory unit. We have investigated the bistable resistance switching in current-voltage (I-V) characteristics of organic diode based on copper phthalocyanine (CuPc) film sandwiched between aluminum (Al) electrodes. Pronounced hysteresis in the I-V curves revealed a resistance switching with on-off ratio of the order of 85%. In order to control the charge injection in the CuPc, nanoscale indium oxide buffer layer was inserted to form Al/CuPc/In2O3/Al device. Analysis of I-V measurements revealed space charge limited switching conduction at the Al/CuPc interface. The traps in the organic layer and charge blocking by oxide insertion layer have been used to explain the absence of resistance switching in the oxide buffer layered memory device cell. Present study offer potential applications for CuPc organic semiconductor in low power non volatile resistive switching memory and logic circuits.

  19. An RBS study of thin PLD and MOCVD strontium copper oxide layers

    Energy Technology Data Exchange (ETDEWEB)

    Kantor, Z. [Institute of Physics, University of Pannonia, H-8200 Veszprem (Hungary); Papadopoulou, E.L.; Aperathitis, E. [Inst. Electronic Struture and Laser, Foundation for Research and Technology - Hellas, P.O. Box 1527, Heraklion 71110 (Greece); Deschanvres, J.-L. [LMPG INP Grenoble-Minatec, BP 257, 38016 Grenoble Cedex 1 (France); Somogyi, K. [MicroVacuum Ltd., Kerekgyarto u.: 10, H-1147 Budapest (Hungary)], E-mail: karoly.somogyi@microvacuum.com; Szendro, I. [MicroVacuum Ltd., Kerekgyarto u.: 10, H-1147 Budapest (Hungary)

    2008-09-30

    Strontium copper oxide (SCO) has been studied as p-type transparent (VIS) conductive oxide material. Also theoretical studies suggested p-type conductivity of the SrCu{sub 2}O{sub 2} composition. SCO thin layers, with thicknesses of 30-2000 nm, were deposited on glass and silicon substrates both by pulsed laser deposition (PLD) and by MOCVD method. The as-grown layers showed high electrical resistance. Due to an annealing process, the resistivity significantly decreased and the layers showed p-type conductivity. Optical transparency measured on samples grown on glass substrates was found about or above 80%, including also thickness dependence. RBS measurements were applied for the determination of the chemical composition profile of the layers. A comparison revealed some specific differences between as-grown and annealed PLD samples. Due to the annealing, the ratio of oxide phases was changed and a vertical inhomogeneity in chemical composition was observed. Our measurements revealed also the influence of the deposition technique and of the substrate.

  20. Coherent structures in wave boundary layers. Part 2. Solitary motion

    DEFF Research Database (Denmark)

    Sumer, B. Mutlu; Jensen, Palle Martin; Sørensen, Lone B.

    2010-01-01

    This study continues the investigation of wave boundary layers reported by Carstensen, Sumer & Fredsøe (J. Fluid Mech., 2010, part 1 of this paper). The present paper summarizes the results of an experimental investigation of turbulent solitary wave boundary layers, simulated by solitary motion...... the boundary-layer flow experiences a regular array of vortex tubes near the bed over a short period of time during the deceleration stage; and (iii) transitional regime characterized with turbulent spots, revealed by single/multiple, or, sometimes, quite dense spikes in the bed shear stress traces...

  1. Physical and chemical properties of the regional mixed layer of Mexico's Megapolis

    Directory of Open Access Journals (Sweden)

    P. Arnott

    2009-08-01

    Full Text Available The concentration of gases and aerosol particles have been measured at the mountain site of Altzomoni, 4010 m in altitude, located 60 km southeast of Mexico City, 50 km east of Puebla and 70 km northeast of Cuernavaca. The objective of this study was to evaluate the properties of gases and particles in the Regional Mixed Layer (RML of Mexico's Megapolis. Altzomoni is generally above the RML from late evening until late morning at which time the arrival of the RML is marked by increasing concentrations of CO and aerosol particles that reach their maxima in mid-afternoon. The average diurnal cycles for fourteen days in March, 2006 were evaluated during which time the synoptic scale circulation had three principal patterns: from the east (E, southwest (SW and west northwest (WNW. The original hypothesis was that air arriving from the direction of Mexico City would have much higher concentrations of anthropogenic gases and particles than air from Puebla or Cuernavaca, due to the relatively large differences in populations. In fact, not only were the average, maximum concentrations of CO and O3 (0.3 and 0.1 ppmv approximately the same for air originating from the WNW and E, but the average maximum concentrations of Peroxyacyl nitrates (PAN,PPN and particle organic matter (POM in air from the E exceeded those in air from the WNW. Comparisons of measurements from the mountain site with those made by aircraft during the same period, using the same type of aerosol mass spectrometer, show that the total masses of POM, NO3−, SO42− and NH4+ were approximately the same from aircraft measurements made over Mexico City and when winds were from the east at the mountain site. In contrast 75% of the total aerosol mass at the mountain site was POM whereas over Mexico City the fraction of POM was less than 60%. The measurements suggest the occasional influence of emissions from the nearby volcano, Popocatepetl, as well as possible incursions of biomass

  2. An IR Sounding-Based Analysis of the Saharan Air Layer in North Africa

    Science.gov (United States)

    Nicholls, Stephen D.; Mohr, Karen I.

    2018-01-01

    captured by both AIRS and model analysis, but the former favor layers than are thinner than observations. Finally, further analysis of HYSPLIT trajectories revealed that fewer than 10% and 33% of all SAL back trajectories passed through regions with notable precipitation (>100 mm accumulated along the trajectory path) or Aerosol Optical Depth (AOD greater than 0.4, 75th percentile of AOD) on average, respectively. Trajectory analysis indicated that only 57% of Saharan and 24% of non-Saharan WMLs are definitively of Saharan origin (Saharan requirement: Two consecutive days in Sahara and 24 or more of those hours within 72 hours of detection). Non-SAL WMLs either originate from local-to-regionally generated residual layers or from mid-latitude air streams that do not linger over the Sahara for a sufficient time period. Initial analysis shows these non-SAL WMLs tend to be both notably cooler and slightly moister than their SAL counter parts. Continuing analysis will address what role Saharan and non-Saharan air masses characteristics may play on local and regional environmental conditions.

  3. Preparation of insulin-containing microcapsules by a layer-by-layer deposition of concanavalin A and glycogen.

    Science.gov (United States)

    Sato, Katsuhiko; Kodama, Daisuke; Endo, Yoshihiro; Anzai, Jun-ichi

    2009-01-01

    The sugar sensitive microcapsules were prepared by a layer-by-layer deposition of concanavalin A (Con A) and glycogen on a calcium carbonate particle containing fluorescein-labeled insulin (F-insulin). The Con A/glycogen multilayer capsules were formed through sugar-lectin interactions by using inner and outer poly(ethyleneimine)/poly(vinyl sulfate) multilayers as supports, while without the supports the microcapsules could not be formed. Fluorescent microscope observations revealed that the capsules thus prepared are spherical in shape with 3-10 microm diameter. The microcapsules released encapsulated F-insulin upon addition of sugars. This is because the added sugars replace glycogen in the binding site of Con A, resulting in the enhanced permeability of the microcapsules to insulin.

  4. Laser-excited photoluminescence of three-layer GaAs double-heterostructure laser material

    International Nuclear Information System (INIS)

    Nash, F.R.; Dixon, R.W.; Barnes, P.A.; Schumaker, N.E.

    1975-01-01

    The successful fabrication of high-quality DH GaAs lasers from a simplified three-layer structure is reported. A major asset of this structure is the transparency of its final layer to recombination radiation occurring in the active layer, thus permitting the use of nondestructive photoluminescent techniques for material evaluation prior to device fabrication. In the course of photoluminescence investigations on this material the additional important observation has been made that indirect excitation (in which photocarriers are generated in the top ternary layer) has significant advantages over direct excitation (in which photocarriers are generated directly in the active layer). These include (i) the direct measurement of Al concentrations in both upper layers, (ii) the measurements of the minority-carrier diffusion length in the upper layer, (iii) an easily obtained indication of taper in the thickness of the upper layer, and (iv) surprisingly effective excitation of the active layer. By combining direct and indirect excitation it is shown that a clearer understanding of the location and detrimental influences of defects in the GaAs laser structure may be obtained. For example, the width of the region of reduced luminescence associated with many defects is found to be very excitation dependent and is confirmed to arise fr []m reduced active region luminescence. The photoluminescent excitation techniques described should be useful in the study of other heterostructure devices and material systems

  5. Migration of Frosts from High-Albedo Regions of Pluto: what New Horizons Reveals

    Science.gov (United States)

    Buratti, Bonnie J.; Stern, S. A.; Weaver, Hal A.; Young, Leslie A.; Olkin, Cathy B.; Ennico, Kimberly; Binzel, Richard P.; Zangari, Amanda; Earle, Alissa M.

    2015-11-01

    With its high eccentricity and obliquity, Pluto should exhibit seasonal volatile transport on its surface. Several lines of evidence support this transport: doubling of Pluto’s atmospheric pressure over the past two decades (Young et al., 2013, Ap. J. 766, L22; Olkin et al., 2015, Icarus 246, 230); changes in its historical rotational light curve, once all variations due to viewing geometry have been modelled (Buratti et al., 2015; Ap. J. 804, L6); and changes in HST albedo maps (Buie et al., 2010, Astron. J. 139, 1128). New Horizons LORRI images reveal that the region of greatest albedo change is not the polar cap(s) of Pluto, but the feature informally named Tombaugh Regio (TR). This feature has a normal reflectance as high as ~0.8 in some places, and it is superposed on older, lower-albedo pre-existing terrain with an albedo of only ~0.10. This contrast is larger than any other body in the Solar System, except for Iapetus. This albedo dichotomy leads to a complicated system of cold-trapping and thermal segregation, beyond the simple picture of seasonal volatile transport. Whatever the origin of TR, it initially acted as a cold trap, as the temperature differential between the high and low albedo regions could be enormous, possibly approaching 20K, based on their albedo differences and assuming their normalized phase curves are similar. This latter assumption will be refined as the full New Horizons data set is returned.Over six decades of ground-based photometry suggest that TR has been decreasing in albedo over the last 25 years. Possible causes include changing insolation angles, or sublimation from the edges where the high-albedo material impinges on a much warmer substrate.Funding by the NASA New Horizons Project acknowledged.

  6. On the processing, microstructure, mechanical and wear properties of cermet/stainless steel layer composites

    International Nuclear Information System (INIS)

    Farid, Akhtar; Guo Shiju

    2007-01-01

    This study deals with layer composites of carbide reinforcements and stainless steel prepared successfully by powder technology. The layer material consisted of two layers. The top layer consisted of reinforcements (TiC and NbC) and 465 stainless steel as the binder material for the carbides. The bottom layer was entirely of binder material (465 stainless steel). The microstructure of the composite was characterized by scanning electron microscopy. The microstructural study revealed that the top layer (TiC-NbC/465 stainless steel) showed the typical core-rim microstructure of conventional steel bonded cermets and the bottom layer showed the structure of sintered steel. An intermediate layer was found with a gradient microstructure, having a higher carbide content towards the cermet layer and lower carbide content towards the stainless steel layer. The bending strength of the layered material measured in the direction perpendicular to the layer alignment was remarkably high. The variation of strength as a function of the thickness of the bottom layer revealed that the character of the material changed from the cermet, to a layer composite and then towards metallic materials. The wear resistance of the top layer was studied against high speed steel. The wear mechanisms were discussed by means of microscopical observations on the worn surfaces. The wear was severe at higher wear loads and lower TiC content. Microploughing of the stainless steel matrix was found to be the dominant wear mechanism. Heavy microploughing and rapid removal of material from the wear surface was observed at high wear load. The fracture morphologies of the top, bottom and intermediate layers are reported

  7. A-type and B-type lamins initiate layer assembly at distinct areas of the nuclear envelope in living cells

    Energy Technology Data Exchange (ETDEWEB)

    Furukawa, Kazuhiro, E-mail: furukawa@chem.sc.niigata-u.ac.jp [Department of Chemistry, Faculty of Science, Niigata University, Niigata 950-2181 (Japan); Ishida, Kazuya; Tsunoyama, Taka-aki; Toda, Suguru; Osoda, Shinichi; Horigome, Tsuneyoshi [Department of Chemistry, Faculty of Science, Niigata University, Niigata 950-2181 (Japan); Fisher, Paul A. [Department of Pharmacological Sciences, School of Medicine, University Medical Center, State University of New York at Stony Brook, Stony Brook, NY 11794-8651 (United States); Sugiyama, Shin [Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602 (Japan)

    2009-04-15

    To investigate nuclear lamina re-assembly in vivo, Drosophila A-type and B-type lamins were artificially expressed in Drosophila lamin Dm{sub 0}null mutant brain cells. Both exogenous lamin C (A-type) and Dm{sub 0} (B-type) formed sub-layers at the nuclear periphery, and efficiently reverted the abnormal clustering of the NPC. Lamin C initially appeared where NPCs were clustered, and subsequently extended along the nuclear periphery accompanied by the recovery of the regular distribution of NPCs. In contrast, lamin Dm{sub 0} did not show association with the clustered NPCs during lamina formation and NPC spacing recovered only after completion of a closed lamin Dm{sub 0} layer. Further, when lamin Dm{sub 0} and C were both expressed, they did not co-polymerize, initiating layer formation in separate regions. Thus, A and B-type lamins reveal differing properties during lamina assembly, with A-type having the primary role in organizing NPC distribution. This previously unknown complexity in the assembly of the nuclear lamina could be the basis for intricate nuclear envelope functions.

  8. Hydroclimatic variability in the Lake Mondsee region and its relationships with large-scale climate anomaly patterns

    Science.gov (United States)

    Rimbu, Norel; Ionita, Monica; Swierczynski, Tina; Brauer, Achim; Kämpf, Lucas; Czymzik, Markus

    2017-04-01

    Flood triggered detrital layers in varved sediments of Lake Mondsee, located at the northern fringe of the European Alps (47°48'N,13°23'E), provide an important archive of regional hydroclimatic variability during the mid- to late Holocene. To improve the interpretation of the flood layer record in terms of large-scale climate variability, we investigate the relationships between observational hydrological records from the region, like the Mondsee lake level, the runoff of the lake's main inflow Griesler Ache, with observed precipitation and global climate patterns. The lake level shows a strong positive linear trend during the observational period in all seasons. Additionally, lake level presents important interannual to multidecadal variations. These variations are associated with distinct seasonal atmospheric circulation patterns. A pronounced anomalous anticyclonic center over the Iberian Peninsula is associated with high lake levels values during winter. This center moves southwestward during spring, summer and autumn. In the same time, a cyclonic anomaly center is recorded over central and western Europe. This anomalous circulation extends southwestward from winter to autumn. Similar atmospheric circulation patterns are associated with river runoff and precipitation variability from the region. High lake levels are associated with positive local precipitation anomalies in all seasons as well as with negative local temperature anomalies during spring, summer and autumn. A correlation analysis reveals that lake level, runoff and precipitation variability is related to large-scale sea surface temperature anomaly patterns in all seasons suggesting a possible impact of large-scale climatic modes, like the North Atlantic Oscillation and Atlantic Multidecadal Oscillation on hydroclimatic variability in the Lake Mondsee region. The results presented in this study can be used for a more robust interpretation of the long flood layer record from Lake Mondsee sediments

  9. Effect of externally generated turbulence on wave boundary layer

    DEFF Research Database (Denmark)

    Fredsøe, Jørgen; Sumer, B. Mutlu; Kozakiewicz, A.

    2003-01-01

    This experimental study deals with the effect of externally generated turbulence on the oscillatory boundary layer to simulate the turbulence in the wave boundary layer under broken waves in the swash zone. The subject has been investigated experimentally in a U-shaped, oscillating water tunnel...... results. The mean and turbulence quantities in the outer flow region are increased substantially with the introduction of the grids. It is shown that the externally generated turbulence is able to penetrate the bed boundary layer, resulting in an increase in the bed shear stress, and therefore...

  10. Formation of the outer layer of the Dictyostelium spore coat depends on the inner-layer protein SP85/PsB.

    Science.gov (United States)

    Metcalf, Talibah; Kelley, Karen; Erdos, Gregory W; Kaplan, Lee; West, Christopher M

    2003-02-01

    The Dictyostelium spore is surrounded by a 220 microm thick trilaminar coat that consists of inner and outer electron-dense layers surrounding a central region of cellulose microfibrils. In previous studies, a mutant strain (TL56) lacking three proteins associated with the outer layer exhibited increased permeability to macromolecular tracers, suggesting that this layer contributes to the coat permeability barrier. Electron microscopy now shows that the outer layer is incomplete in the coats of this mutant and consists of a residual regular array of punctate electron densities. The outer layer is also incomplete in a mutant lacking a cellulose-binding protein associated with the inner layer, and these coats are deficient in an outer-layer protein and another coat protein. To examine the mechanism by which this inner-layer protein, SP85, contributes to outer-layer formation, various domain fragments were overexpressed in forming spores. Most of these exert dominant negative effects similar to the deletion of outer-layer proteins, but one construct, consisting of a fusion of the N-terminal and Cys-rich C1 domain, induces a dense mat of novel filaments at the surface of the outer layer. Biochemical studies show that the C1 domain binds cellulose, and a combination of site-directed mutations that inhibits its cellulose-binding activity suppresses outer-layer filament induction. The results suggest that, in addition to a previously described early role in regulating cellulose synthesis, SP85 subsequently contributes a cross-bridging function between cellulose and other coat proteins to organize previously unrecognized structural elements in the outer layer of the coat.

  11. Free double layers in mercury-arc discharges

    International Nuclear Information System (INIS)

    Maciel, H.S.; Allen, J.E.

    1989-01-01

    A study has been carried out of free double layers formed within the plasma volume of a low-pressure mercury-arc discharge at high current densities. The free double layer is observed to form as a visible boundary, which drifts slowly from the central section of the discharge. Current-driven instabilities are observed as the discharge current is gradually increased to a critical value, at which current limitation is observed to occur. This process, which is accompanied by high-current spikes, ceases when the free double layer becomes visible as a sharp boundary dividing the discharge column into two regions of different luminosities. The layer is observed to form in the later stages of current limitation, the onset of which occurs for a ratio of drift to thermal speed of electrons of about unity. Electrical energy is converted by the layer into kinetic energy of the changed particles. Accordingly high-energy ions were measured by means of an electrostatic energy analyser. The multiple-sheath character of the free 'double layer'', which is inferred from probe measurements of potential profiles, is discussed and comparisons with other space-charge structures with the same topology are made. (author)

  12. Unsteady turbulent boundary layers in swimming rainbow trout.

    Science.gov (United States)

    Yanase, Kazutaka; Saarenrinne, Pentti

    2015-05-01

    The boundary layers of rainbow trout, Oncorhynchus mykiss, swimming at 1.02±0.09 L s(-1) (mean±s.d., N=4), were measured by the particle image velocimetry (PIV) technique at a Reynolds number of 4×10(5). The boundary layer profile showed unsteadiness, oscillating above and beneath the classical logarithmic law of the wall with body motion. Across the entire surface regions that were measured, local Reynolds numbers based on momentum thickness, which is the distance that is perpendicular to the fish surface through which the boundary layer momentum flows at free-stream velocity, were greater than the critical value of 320 for the laminar-to-turbulent transition. The skin friction was dampened on the convex surface while the surface was moving towards a free-stream flow and increased on the concave surface while retreating. These observations contradict the result of a previous study using different species swimming by different methods. Boundary layer compression accompanied by an increase in local skin friction was not observed. Thus, the overall results may not support absolutely the Bone-Lighthill boundary layer thinning hypothesis that the undulatory motions of swimming fish cause a large increase in their friction drag because of the compression of the boundary layer. In some cases, marginal flow separation occurred on the convex surface in the relatively anterior surface region, but the separated flow reattached to the fish surface immediately downstream. Therefore, we believe that a severe impact due to induced drag components (i.e. pressure drag) on the swimming performance, an inevitable consequence of flow separation, was avoided. © 2015. Published by The Company of Biologists Ltd.

  13. Ordered mixed-layer structures in the Mighei carbonaceous chondrite matrix

    Science.gov (United States)

    Mackinnon, I. D. R.

    1982-01-01

    High resolution transmission electron microscopy of the Mighei carbonaceous chondrite matrix has revealed the presence of a new mixed layer structure material. This mixed-layer material consists of an ordered arrangement of serpentine-type (S) and brucite-type (B) layers in the sequence SBBSBB. Electron diffraction and imaging techniques show that the basal periodicity is approximately 17 A. Discrete crystals of SBB-type material are typically curved, of small size (less than 1 micron) and show structural variations similar to the serpentine group minerals. Mixed-layer material also occurs in association with planar serpentine. Characteristics of SBB-type material are not consistent with known terrestrial mixed-layer clay minerals. Evidence for formation by a condensation event or by subsequent alteration of pre-existing material is not yet apparent.

  14. Automated gray level index measurements reveal only minor cytoarchitectonic changes of Brodmann area 9 in schizophrenia.

    Science.gov (United States)

    Tepest, Ralf; Vogeley, Kai; Viebahn, Bettina; Schneider-Axmann, Thomas; Honer, William G; Falkai, Peter

    2008-07-15

    Using an automatized gray level index (GLI) method, we recently found cytoarchitectonic abnormalities in schizophrenia in Brodmann area 10 (BA10) [Vogeley, K., Tepest, R., Schneider-Axmann, T., Hutte, H., Zilles, K., Honer, W.G., Falkai, P., 2003. Automated image analysis of disturbed cytoarchitecture in Brodmann area 10 in schizophrenia, Schizophrenia Research 62, 133-140]. As another potential key region involved in the pathophysiology of schizophrenia, we have now investigated BA9 in the same sample consisting of 20 schizophrenic cases and 20 controls. The GLI value represents the area-percentage covered by perikarya in measuring fields of microscopic images. BA9 was analyzed with respect to the factors diagnosis and gender for six different compartments approximately corresponding to the neocortical layers. The main result in BA9 was a significant interaction of diagnosis and gender for GLI in layers IV and V on the left side. Subsequent analyses separately performed concerning gender revealed a significant GLI increase in layer V on the left side in male patients compared with controls. However, after an adjustment of error probabilities for multiple testing, differences did not reach significance. No GLI difference was observed in the sample between diagnostic groups for females and between the diagnostic groups in general. Comparisons with our BA10 results suggest that cytoarchitectural changes relevant to schizophrenia appear different in various Brodmann areas. Since increases in GLI were found only in selected layers (V and VI) of BA9, these findings do not support a generalized neuropil reduction across all cortical layers.

  15. Budget of Turbulent Kinetic Energy in a Shock Wave Boundary-Layer Interaction

    Science.gov (United States)

    Vyas, Manan A.; Waindim, Mbu; Gaitonde, Datta V.

    2016-01-01

    Implicit large-eddy simulation (ILES) of a shock wave/boundary-layer interaction (SBLI) was performed. Quantities present in the exact equation of the turbulent kinetic energy transport were accumulated and used to calculate terms like production, dissipation, molecular diffusion, and turbulent transport. The present results for a turbulent boundary layer were validated by comparison with direct numerical simulation data. It was found that a longer development domain was necessary for the boundary layer to reach an equilibrium state and a finer mesh resolution would improve the predictions. In spite of these findings, trends of the present budget match closely with that of the direct numerical simulation. Budgets for the SBLI region are presented at key axial stations. These budgets showed interesting dynamics as the incoming boundary layer transforms and the terms of the turbulent kinetic energy budget change behavior within the interaction region.

  16. Combining tower mixing ratio and community model data to estimate regional-scale net ecosystem carbon exchange by boundary layer inversion over four flux towers in the United States

    Science.gov (United States)

    Xueri Dang; Chun-Ta Lai; David Y. Hollinger; Andrew J. Schauer; Jingfeng Xiao; J. William Munger; Clenton Owensby; James R. Ehleringer

    2011-01-01

    We evaluated an idealized boundary layer (BL) model with simple parameterizations using vertical transport information from community model outputs (NCAR/NCEP Reanalysis and ECMWF Interim Analysis) to estimate regional-scale net CO2 fluxes from 2002 to 2007 at three forest and one grassland flux sites in the United States. The BL modeling...

  17. Investigation of the effect of potassium on Cu(In,Ga)Se{sub 2} layers and solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Laemmle, A., E-mail: anke.laemmle@zsw-bw.de; Wuerz, R.; Powalla, M.

    2015-05-01

    We investigate the influence of potassium (K) on the Cu(In,Ga)Se{sub 2} (CIGS) growth kinetics on alkali-free alumina substrates and the electrical parameters of the CIGS solar cell by intentional K doping of the CIGS layer by a KF-precursor layer and KF-post deposition treatment (PDT). Secondary ion mass spectroscopy measurements revealed that K can be incorporated into the CIGS layer by both processes. The CIGS composition of the KF-precursor sample shows a stronger [Ga]/([Ga] + [In]) (GGI) profile. By analysing the samples with scanning electron microscopy we observed smaller CIGS grains for the KF-precursor sample compared to the K-free reference and KF-PDT sample. jV-measurements of the KF-PDT and the KF-precursor sample show an increase in the cell efficiency η from 10.7% to 13.6% and 13.7%, respectively, compared to the K-free reference sample. The external quantum efficiency measurements of the KF-precursor sample show an increased absorption in the infrared region. Capacitance-voltage measurements reveal an increase in the net doping concentration of both samples treated with K. We assume that the enhancement is caused by passivation of grain boundaries and donor-like defects by K, as previously demonstrated for Na. - Highlights: • K-doped Cu(In,Ga)Se{sub 2} (CIGS) layers from KF-precursor and KF-post deposition treatment • Separation of the K-effect from the Na-effect by using alkali-free substrates • Interdiffusion of CIGS elements during CIGS growth is hindered by K • KF-precursor leads to smaller CIGS grains and a stronger Cu depletion at the CIGS surface. • K leads to an increase in the conversion efficiency.

  18. Fabrication and stability investigation of ultra-thin transparent and flexible Cu-Ag-Au tri-layer film on PET

    Science.gov (United States)

    Prakasarao, Ch Surya; D'souza, Slavia Deeksha; Hazarika, Pratim; Karthiselva N., S.; Ramesh Babu, R.; Kovendhan, M.; Kumar, R. Arockia; Joseph, D. Paul

    2018-04-01

    The need for transparent conducting electrodes with high transmittance, low sheet resistance and flexibility to replace Indium Tin Oxide is ever growing. We have deposited and studied the performance of ultra-thin Cu-Ag-Au tri-layer films over a flexible poly-ethylene terephthalate substrate. Scotch tape test showed good adhesion of the metallic film. Transmittance of the tri-layer was around 40 % in visible region. Optical profiler measurements were done to study the surface features. The XRD pattern revealed that film was amorphous. Sheet resistance measured by four probe technique was around 7.7 Ohm/Δ and was stable up to 423 K. The transport parameters by Hall effect showed high conductivity and carrier concentration with a mobility of 5.58 cm2/Vs. Tests performed in an indigenously designed bending unit indicated the films to be stable both mechanically and electrically even after 50,000 bending cycles.

  19. Characterizing the Asian Tropopause Aerosol Layer using in situ balloon measurements: the BATAL campaigns of 2014-2017

    Science.gov (United States)

    Fairlie, T. D.; Vernier, J. P.; Deshler, T.; Pandit, A. K.; Ratnam, M. V.; Gadhavi, H. S.; Liu, H.; Natarajan, M.; Jayaraman, A.; Kumar, S.; Singh, A. K.; Stenchikov, G. L.; Wienhold, F.; Vignelles, D.; Bedka, K. M.; Avery, M. A.

    2017-12-01

    We present in situ balloon observations of the Asian Tropopause Aerosol Layer (ATAL), a summertime accumulation of aerosols in the upper troposphere and lower stratosphere (UTLS), associated with Asian Summer Monsoon (ASM). The ATAL was first revealed by CALIPSO satellite data, and has been linked with deep convection of boundary layer pollution into the UTLS. The ATAL has potential implications for regional cloud properties, radiative transfer, and chemical processes in the UTLS. The "Balloon measurements of the Asian Tropopause Aerosol Layer (BATAL)" field campaigns to India and Saudi Arabia in were designed to characterize the physical and optical properties of the ATAL, to explore its composition, and its relationship with clouds in the UTLS. We launched 55 balloon flights from 4 locations, in summers 2014-2016. We return to India to make more balloon flights in summer 2017. Balloon payloads range from 500g to 50 kg, making measurements of meteorological parameters, ozone, water vapor, aerosol optical properties, concentration, volatility, and composition in the UTLS region. This project represents the most important effort to date to study UTLS aerosols during the ASM, given few in situ observations. We complement the in situ data presented with 3-d chemical transport simulations, designed to further explore the ATAL's chemical composition, the sensitivity of such to scavenging in parameterized deep convection, and the relative contribution of regional vs. rest-of-the-world pollution sources. The BATAL project has been a successful partnership between institutes in the US, India, Saudi Arabia, and Europe, and continues for the next 3-4 years, sponsored by the NASA Upper Atmosphere Research program. This partnership may provide a foundation for potential high-altitude airborne measurement studies during the ASM in the future.

  20. Receptivity of Hypersonic Boundary Layers to Acoustic and Vortical Disturbances (Invited)

    Science.gov (United States)

    Balakumar, P.

    2015-01-01

    Boundary-layer receptivity to two-dimensional acoustic and vortical disturbances for hypersonic flows over two-dimensional and axi-symmetric geometries were numerically investigated. The role of bluntness, wall cooling, and pressure gradients on the receptivity and stability were analyzed and compared with the sharp nose cases. It was found that for flows over sharp nose geometries in adiabatic wall conditions the instability waves are generated in the leading-edge region and that the boundary layer is much more receptive to slow acoustic waves as compared to the fast waves. The computations confirmed the stabilizing effect of nose bluntness and the role of the entropy layer in the delay of boundary layer transition. The receptivity coefficients in flows over blunt bodies are orders of magnitude smaller than that for the sharp cone cases. Wall cooling stabilizes the first mode strongly and destabilizes the second mode. However, the receptivity coefficients are also much smaller compared to the adiabatic case. The adverse pressure gradients increased the unstable second mode regions.

  1. A successive ionic layer adsorption and reaction (SILAR) method to fabricate a layer-by-layer (LbL) MnO2-reduced graphene oxide assembly for supercapacitor application

    Science.gov (United States)

    Jana, Milan; Saha, Sanjit; Samanta, Pranab; Murmu, Naresh Chandra; Kim, Nam Hoon; Kuila, Tapas; Lee, Joong Hee

    2017-02-01

    A facile, cost effective and additive-free successive ionic layer adsorption and reaction (SILAR) technique is demonstrated to develop layer-by-layer (LbL) assembly of reduced graphene oxide (RGO) and MnO2 (MnO2-RGOSILAR) on a stainless steel current collector, for designing light-weight and small size supercapacitor electrode. The transmission electron microscopy and field emission scanning electron microscopy images shows uniform distribution of RGO and MnO2 in the MnO2-RGOSILAR. The LbL (MnO2-RGOSILAR) demonstrates improved physical and electrochemical properties over the hydrothermally prepared MnO2-RGO (MnO2-RGOHydro). The electrochemical environment of MnO2-RGOSILAR is explained by constant phase element in the high frequency region, and a Warburg element in the low frequency region in the Z-View fitted Nyquist plot. The equivalent circuit of the MnO2-RGOHydro, displays the co-existence of EDL and constant phase element, indicating inhomogeneous distribution of MnO2 and RGO by the hydrothermal technique. An asymmetric supercapacitor device is designed with MnO2-RGOSILAR as positive electrode, and thermally reduced GO (TRGO) as negative electrode. The designed cell exhibits high energy density of ∼88 Wh kg-1, elevated power density of ∼23,200 W kg-1, and ∼79% retention in capacitance after 10,000 charge-discharge cycles.

  2. Layer-by-Layer technique employed to construct multitask interfaces in polymer composites

    Directory of Open Access Journals (Sweden)

    Luísa Sá Vitorino

    Full Text Available Abstract The properties of glass fiber-reinforced polymer composites are closely related to the fiber-matrix interface. Interfacial treatments to improve mechanical properties are usually limited to enhance interfacial adhesion. In this work, Layer-by-Layer (LbL technique was introduced to build a novel interface in polymer composites. Different numbers of bilayers of poly(diallyldimethylammonium chloride and poly(sodium 4-styrenesulfonate with carbon nanotubes were deposited through LbL on the surface of woven glass fibers (GFs. Polypropylene composites containing the modified GFs were prepared by compression molding. Thermogravimetric analysis, scanning electron microscopy and Raman spectroscopy proved that multilayers of polymers with carbon nanotubes could be deposited on GFs surface. Mechanical tests on composites with modified GFs revealed an increase in Flexural Modulus and toughness. The overall results attested that the LbL technique can be used to design interfaces with different compositions to perform diverse tasks, such as to improve the stiffness of composites and to encapsulate active nanocomponents.

  3. Asymptotic theory of double layer and shielding of electric field at the edge of illuminated plasma

    Energy Technology Data Exchange (ETDEWEB)

    Benilov, M. S. [Departamento de Física, CCCEE, Universidade da Madeira, Largo do Município, 9000 Funchal (Portugal); Thomas, D. M. [Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BW (United Kingdom)

    2014-04-15

    The method of matched asymptotic expansions is applied to the problem of a collisionless plasma generated by UV illumination localized in a central part of the plasma in the limiting case of small Debye length λ{sub D}. A second-approximation asymptotic solution is found for the double layer positioned at the boundary of the illuminated region and for the un-illuminated plasma for the plane geometry. Numerical calculations for different values of λ{sub D} are reported and found to confirm the asymptotic results. The net integral space charge of the double layer is asymptotically small, although in the plane geometry it is just sufficient to shield the ambipolar electric field existing in the illuminated region and thus to prevent it from penetrating into the un-illuminated region. The double layer has the same mathematical nature as the intermediate transition layer separating an active plasma and a collisionless sheath, and the underlying physics is also the same. In essence, the two layers represent the same physical object: a transonic layer.

  4. Atomic force microscopy stiffness tomography on living Arabidopsis thaliana cells reveals the mechanical properties of surface and deep cell-wall layers during growth.

    Science.gov (United States)

    Radotić, Ksenija; Roduit, Charles; Simonović, Jasna; Hornitschek, Patricia; Fankhauser, Christian; Mutavdžić, Dragosav; Steinbach, Gabor; Dietler, Giovanni; Kasas, Sandor

    2012-08-08

    Cell-wall mechanical properties play a key role in the growth and the protection of plants. However, little is known about genuine wall mechanical properties and their growth-related dynamics at subcellular resolution and in living cells. Here, we used atomic force microscopy (AFM) stiffness tomography to explore stiffness distribution in the cell wall of suspension-cultured Arabidopsis thaliana as a model of primary, growing cell wall. For the first time that we know of, this new imaging technique was performed on living single cells of a higher plant, permitting monitoring of the stiffness distribution in cell-wall layers as a function of the depth and its evolution during the different growth phases. The mechanical measurements were correlated with changes in the composition of the cell wall, which were revealed by Fourier-transform infrared (FTIR) spectroscopy. In the beginning and end of cell growth, the average stiffness of the cell wall was low and the wall was mechanically homogenous, whereas in the exponential growth phase, the average wall stiffness increased, with increasing heterogeneity. In this phase, the difference between the superficial and deep wall stiffness was highest. FTIR spectra revealed a relative increase in the polysaccharide/lignin content. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  5. Structure measurements in a synthetic turbulent boundary layer

    Science.gov (United States)

    Arakeri, Jaywant H.

    1987-09-01

    Extensive hot-wire measurements have been made to determine the structure of the large eddy in a synthejc turbulent boundary layer on a flat-plate model. The experiments were carried out in a wind tunnel at a nominal free-stream velocity of 12 m/s. The synthetic turbulent boundary layer had a hexagonal pattern of eddies and a ratio of streamwise scale to spanwise scale of 3.2:1. The measured celerity of the large eddy was 84.2 percent of the free-stream velocity. There was some loss of coherence, but very little distortion, as the eddies moved downstream. Several mean properties of the synthetic boundary layer were found to agree quite well with the mean properties of a natural turbulent boundary layer at the same Reynolds number. The large eddy is composed of a pair of primary counter-rotating vortices about five [...] long in the streamwise direction and about one [...] apart in the spanwise direction, where [...] is the mean boundary-layer thickness. The sense of the primary pair is such as to pump fluid away from the wall in the region between the vortices. A secondary pair of counter-rotating streamwise vortices, having a sense opposite to that of the primary pair, is observed outside of and slightly downstream from the primary vortices. Both pairs of vortices extend across the full thickness of the boundary layer and are inclined at a shallow angle to the surface of the flat plate. The data show that the mean vorticity vectors are not tangential to the large-eddy vortices. In fact, the streamwise and normal vorticity components that signal the presence of the eddy are of the same order of magnitude. Definite signatures are obtained in terms of the mean skin-friction coefficient and the mean wake parameter averaged at constant phase. Velocities induced by the vortices are partly responsible for entrainment of irrotational fluid, for transport of momentum, for generation of Reynolds stresses, and for maintenance of streamwise and normal vorticity in the outer

  6. On the porosity of barrier layers

    Directory of Open Access Journals (Sweden)

    J. Mignot

    2009-09-01

    Full Text Available Barrier layers are defined as the layer between the pycnocline and the thermocline when the latter are different as a result of salinity stratification. We present a revisited 2-degree resolution global climatology of monthly mean oceanic Barrier Layer (BL thickness first proposed by de Boyer Montégut et al. (2007. In addition to using an extended data set, we present a modified computation method that addresses the observed porosity of BLs. We name porosity the fact that barrier layers distribution can, in some areas, be very uneven regarding the space and time scales that are considered. This implies an intermittent alteration of air-sea exchanges by the BL. Therefore, it may have important consequences for the climatic impact of BLs. Differences between the two computation methods are small for robust BLs that are formed by large-scale processes. However, the former approach can significantly underestimate the thickness of short and/or localized barrier layers. This is especially the case for barrier layers formed by mesoscale mechanisms (under the intertropical convergence zone for example and along western boundary currents and equatorward of the sea surface salinity subtropical maxima. Complete characterisation of regional BL dynamics therefore requires a description of the robustness of BL distribution to assess the overall impact of BLs on the process of heat exchange between the ocean interior and the atmosphere.

  7. Observations of high droplet number concentrations in Southern Ocean boundary layer clouds

    Directory of Open Access Journals (Sweden)

    T. Chubb

    2016-01-01

    Full Text Available Cloud physics data collected during the NSF/NCAR High-performance Instrumented Airborne Platform for Environmental Research (HIAPER Pole-to-Pole Observations (HIPPO campaigns provide a snapshot of unusual wintertime microphysical conditions in the boundary layer over the Southern Ocean. On 29 June 2011, the HIAPER sampled the boundary layer in a region of pre-frontal warm air advection between 58 and 48° S to the south of Tasmania. Cloud droplet number concentrations were consistent with climatological values in the northernmost profiles but were exceptionally high for wintertime in the Southern Ocean at 100–200 cm−3 in the southernmost profiles. Sub-micron (0.06  < D <  1 µm aerosol concentrations for the southern profiles were up to 400 cm−3. Analysis of back trajectories and atmospheric chemistry observations revealed that while conditions in the troposphere were more typical of a clean remote ocean airmass, there was some evidence of continental or anthropogenic influence. However, the hypothesis of long-range transport of continental aerosol fails to explain the magnitude of the aerosol and cloud droplet concentration in the boundary layer. Instead, the gale force surface winds in this case (wind speed at 167 m above sea level was  > 25 m s−1 were most likely responsible for production of sea spray aerosol which influenced the microphysical properties of the boundary layer clouds. The smaller size and higher number concentration of cloud droplets is inferred to increase the albedo of these clouds, and these conditions occur regularly, and are expected to increase in frequency, over windy parts of the Southern Ocean.

  8. Genome analysis of Excretory/Secretory proteins in Taenia solium reveals their Abundance of Antigenic Regions (AAR).

    Science.gov (United States)

    Gomez, Sandra; Adalid-Peralta, Laura; Palafox-Fonseca, Hector; Cantu-Robles, Vito Adrian; Soberón, Xavier; Sciutto, Edda; Fragoso, Gladis; Bobes, Raúl J; Laclette, Juan P; Yauner, Luis del Pozo; Ochoa-Leyva, Adrián

    2015-05-19

    Excretory/Secretory (ES) proteins play an important role in the host-parasite interactions. Experimental identification of ES proteins is time-consuming and expensive. Alternative bioinformatics approaches are cost-effective and can be used to prioritize the experimental analysis of therapeutic targets for parasitic diseases. Here we predicted and functionally annotated the ES proteins in T. solium genome using an integration of bioinformatics tools. Additionally, we developed a novel measurement to evaluate the potential antigenicity of T. solium secretome using sequence length and number of antigenic regions of ES proteins. This measurement was formalized as the Abundance of Antigenic Regions (AAR) value. AAR value for secretome showed a similar value to that obtained for a set of experimentally determined antigenic proteins and was different to the calculated value for the non-ES proteins of T. solium genome. Furthermore, we calculated the AAR values for known helminth secretomes and they were similar to that obtained for T. solium. The results reveal the utility of AAR value as a novel genomic measurement to evaluate the potential antigenicity of secretomes. This comprehensive analysis of T. solium secretome provides functional information for future experimental studies, including the identification of novel ES proteins of therapeutic, diagnosis and immunological interest.

  9. Heat transfer enhancement in a turbulent natural convection boundary layer along a vertical flat plate

    International Nuclear Information System (INIS)

    Tsuji, Toshihiro; Kajitani, Tsuyoshi; Nishino, Tatsuhiko

    2007-01-01

    An experimental study on heat transfer enhancement for a turbulent natural convection boundary layer in air along a vertical flat plate has been performed by inserting a long flat plate in the spanwise direction (simple heat transfer promoter) and short flat plates aligned in the spanwise direction (split heat transfer promoter) with clearances into the near-wall region of the boundary layer. For a simple heat transfer promoter, the heat transfer coefficients increase by a peak value of approximately 37% in the downstream region of the promoter compared with those in the usual turbulent natural convection boundary layer. It is found from flow visualization and simultaneous measurements of the flow and thermal fields with hot- and cold-wires that such increase of heat transfer coefficients is mainly caused by the deflection of flows toward the outer region of the boundary layer and the invasion of low-temperature fluids from the outer region to the near-wall region with large-scale vortex motions riding out the promoter. However, heat transfer coefficients for a split heat transfer promoter exhibit an increase in peak value of approximately 60% in the downstream region of the promoter. Flow visualization and PIV measurements show that such remarkable heat transfer enhancement is attributed to longitudinal vortices generated by flows passing through the clearances of the promoter in addition to large-scale vortex motions riding out the promoter. Consequently, it is concluded that heat transfer enhancement of the turbulent natural convection boundary layer can be substantially achieved in a wide area of the turbulent natural convection boundary layer by employing multiple column split heat transfer promoters. It may be expected that the heat transfer enhancement in excess of approximately 40% can be accomplished by inserting such promoters

  10. Effects of porosity in a model of corrosion and passive layer growth

    Directory of Open Access Journals (Sweden)

    F.D.A. Aarão Reis

    2017-12-01

    Full Text Available We introduce a stochastic lattice model to investigate the effects of pore formation in a passive layer grown with products of metal corrosion. It considers that an anionic species diffuses across that layer and reacts at the corrosion front (metal-oxide interface, producing a random distribution of compact regions and large pores, respectively represented by O (oxide and P (pore sites. O sites are assumed to have very small pores, so that the fraction Φ of P sites is an estimate of the porosity, and the ratio between anion diffusion coefficients in those regions is D_r0 and D_r≪1, significant changes are observed in passive layer growth and corrosion front roughness. For small Φ, a slowdown of the growth rate is observed, which is interpreted as a consequence of the confinement of anions in isolated pores for long times. However, the presence of large pores near the corrosion front increases the frequency of reactions at those regions, which leads to an increase in the roughness of that front. This model may be a first step to represent defects in a passive layer which favor pitting corrosion.

  11. On Hydromagnetic Stresses in Accretion Disk Boundary Layers

    DEFF Research Database (Denmark)

    Pessah, Martin Elias; Chan, Chi-kwan

    2012-01-01

    Detailed calculations of the physical structure of accretion disk boundary layers, and thus their inferred observational properties, rely on the assumption that angular momentum transport is opposite to the radial angular frequency gradient of the disk. The standard model for turbulent shear...... of efficient angular momentum transport in the inner disk regions. This suggests that the detailed structure of turbulent MHD accretion disk boundary layers could differ appreciably from those derived within the standard framework of turbulent shear viscosity...

  12. Organic photovoltaic devices with a single layer geometry (Conference Presentation)

    Science.gov (United States)

    Kolesov, Vladimir A.; Fuentes-Hernandez, Canek; Aizawa, Naoya; Larrain, Felipe A.; Chou, Wen-Fang; Perrotta, Alberto; Graham, Samuel; Kippelen, Bernard

    2016-09-01

    Organic photovoltaics (OPV) can lead to a low cost and short energy payback time alternative to existing photovoltaic technologies. However, to fulfill this promise, power conversion efficiencies must be improved and simultaneously the architecture of the devices and their processing steps need to be further simplified. In the most efficient devices to date, the functions of photocurrent generation, and hole/electron collection are achieved in different layers adding complexity to the device fabrication. In this talk, we present a novel approach that yields devices in which all these functions are combined in a single layer. Specifically, we report on bulk heterojunction devices in which amine-containing polymers are first mixed in the solution together with the donor and acceptor materials that form the active layer. A single-layer coating yields a self-forming bottom electron-collection layer comprised of the amine-containing polymer (e.g. PEIE). Hole-collection is achieved by subsequent immersion of this single layer in a solution of a polyoxometalate (e.g. phosphomolybdic acid (PMA)) leading to an electrically p-doped region formed by the diffusion of the dopant molecules into the bulk. The depth of this doped region can be controlled with values up to tens of nm by varying the immersion time. Devices with a single 500 nm-thick active layer of P3HT:ICBA processed using this method yield power conversion efficiency (PCE) values of 4.8 ± 0.3% at 1 sun and demonstrate a performance level superior to that of benchmark three-layer devices with separate layers of PEIE/P3HT:ICBA/MoOx (4.1 ± 0.4%). Devices remain stable after shelf lifetime experiments carried-out at 60 °C over 280 h.

  13. Incorporating an Electrode Modification Layer with a Vertical Phase Separated Photoactive Layer for Efficient and Stable Inverted Nonfullerene Polymer Solar Cells.

    Science.gov (United States)

    Shi, Zhenzhen; Liu, Hao; Wang, Yaping; Li, Jinyan; Bai, Yiming; Wang, Fuzhi; Bian, Xingming; Hayat, Tasawar; Alsaedi, Ahmed; Tan, Zhan'ao

    2017-12-20

    For bulk heterojunction polymer solar cells (PSCs), the donors and acceptors featuring specific phase separation and concentration distribution within the electron donor/acceptor blends crucially affect the exciton dissociation and charge transportation. Herein, efficient and stable nonfullerene inverted PSCs incorporating a phase separated photoactive layer and a titanium chelate electrode modification layer are demonstrated. Water contact angle (WCA), scanning kelvin probe microscopy (SKPM), and atomic force microscopy (AFM) techniques are implemented to characterize the morphology of photoactive layers. Compared with the control conventional device, the short-circuit current density (J sc ) is enhanced from 14.74 to 17.45 mAcm -2 . The power conversion efficiency (PCE) for the inverted PSCs with a titanium (diisopropoxide)-bis-(2,4-pentanedionate) (TIPD) layer increases from 9.67% to 11.69% benefiting from the declined exciton recombination and fairly enhanced charge transportation. Furthermore, the nonencapsulated inverted device with a TIPD layer demonstrates the best long-term stability, 85% of initial PCE remaining and an almost undecayed open-circuit voltage (V oc ) after 1440 h. Our results reveal that the titanium chelate is an excellent electrode modification layer to incorporate with a vertical phase separated photoactive layer for producing high-efficiency and high-stability inverted nonfullerene PSCs.

  14. Ultralow threading dislocation density in GaN epilayer on near-strain-free GaN compliant buffer layer and its applications in hetero-epitaxial LEDs.

    Science.gov (United States)

    Shih, Huan-Yu; Shiojiri, Makoto; Chen, Ching-Hsiang; Yu, Sheng-Fu; Ko, Chung-Ting; Yang, Jer-Ren; Lin, Ray-Ming; Chen, Miin-Jang

    2015-09-02

    High threading dislocation (TD) density in GaN-based devices is a long unresolved problem because of the large lattice mismatch between GaN and the substrate, which causes a major obstacle for the further improvement of next-generation high-efficiency solid-state lighting and high-power electronics. Here, we report InGaN/GaN LEDs with ultralow TD density and improved efficiency on a sapphire substrate, on which a near strain-free GaN compliant buffer layer was grown by remote plasma atomic layer deposition. This "compliant" buffer layer is capable of relaxing strain due to the absorption of misfit dislocations in a region within ~10 nm from the interface, leading to a high-quality overlying GaN epilayer with an unusual TD density as low as 2.2 × 10(5) cm(-2). In addition, this GaN compliant buffer layer exhibits excellent uniformity up to a 6" wafer, revealing a promising means to realize large-area GaN hetero-epitaxy for efficient LEDs and high-power transistors.

  15. Non-hydrostatic layered flows over a sill

    International Nuclear Information System (INIS)

    Jamali, Mirmosadegh

    2013-01-01

    This work takes a new approach to solving non-hydrostatic equations of layered flows over bottom topography. A perturbation technique is used to find explicit expressions for a flow for different regimes of single- and two-layer flows over a sill. Excellent agreement with previous solutions and experimental data is obtained, and more details of the non-hydrostatic flow over a sill are revealed. The proposed method is simple and compact and removes the need for complex numerical techniques to solve the non-hydrostatic equations. It is shown that in the approach-controlled regime of two-layer flow over a sill, the flow upstream and farther downstream the sill crest can be described by the hydrostatic theory, and the flow is non-hydrostatic over only a short distance on the downstream side of the crest. (paper)

  16. Active Layer Monitoring, Arctic and Subarctic Canada, Version 6

    Data.gov (United States)

    National Aeronautics and Space Administration — This project involves measuring regional and site variability in maximum annual active layer development and vertical surface movement over permafrost, and...

  17. Boundary layer turbulence in transitional and developed states

    Science.gov (United States)

    Park, George Ilhwan; Wallace, James M.; Wu, Xiaohua; Moin, Parviz

    2012-03-01

    Using the recent direct numerical simulations by Wu and Moin ["Transitional and turbulent boundary layer with heat transfer," Phys. Fluids 22, 85 (2010)] of a flat-plate boundary layer with a passively heated wall, statistical properties of the turbulence in transition at Reθ ≈ 300, from individual turbulent spots, and at Reθ ≈ 500, where the spots merge (distributions of the mean velocity, Reynolds stresses, kinetic energy production, and dissipation rates, enstrophy and its components) have been compared to these statistical properties for the developed boundary layer turbulence at Reθ = 1840. When the distributions in the transitional regions are conditionally averaged so as to exclude locations and times when the flow is not turbulent, they closely resemble the distributions in the developed turbulent state at the higher Reynolds number, especially in the buffer layer. Skin friction coefficients, determined in this conditional manner at the two Reynolds numbers in the transitional flow are, of course, much larger than when their values are obtained by including both turbulent and non-turbulent information there, and the conditional averaged values are consistent with the 1/7th power law approximation. An octant analysis based on the combinations of signs of the velocity and temperature fluctuations, u, v, and θ shows that the momentum and heat fluxes are predominantly of the mean gradient type in both the transitional and developed regions. The fluxes appear to be closely associated with vortices that transport momentum and heat toward and away from the wall in both regions of the flow. The results suggest that there may be little fundamental difference between the nonlinear processes involved in the formation of turbulent spots that appear in transition and those that sustain the turbulence when it is developed. They also support the view that the transport processes and the vortical structures that drive them in developed and transitional boundary

  18. An Improved Iterative Fitting Method to Estimate Nocturnal Residual Layer Height

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2016-08-01

    Full Text Available The planetary boundary layer (PBL is an atmospheric region near the Earth’s surface. It is significant for weather forecasting and for the study of air quality and climate. In this study, the top of nocturnal residual layers—which are what remain of the daytime mixing layer—are estimated by an elastic backscatter Lidar in Wuhan (30.5°N, 114.4°E, a city in Central China. The ideal profile fitting method is widely applied to determine the nocturnal residual layer height (RLH from Lidar data. However, the method is seriously affected by an optical thick layer. Thus, we propose an improved iterative fitting method to eliminate the optical thick layer effect on RLH detection using Lidar. Two typical case studies observed by elastic Lidar are presented to demonstrate the theory and advantage of the proposed method. Results of case analysis indicate that the improved method is more practical and precise than profile-fitting, gradient, and wavelet covariance transform method in terms of nocturnal RLH evaluation under low cloud conditions. Long-term observations of RLH performed with ideal profile fitting and improved methods were carried out in Wuhan from 28 May 2011 to 17 June 2016. Comparisons of Lidar-derived RLHs with the two types of methods verify that the improved solution is practical. Statistical analysis of a six-year Lidar signal was conducted to reveal the monthly average values of nocturnal RLH in Wuhan. A clear RLH monthly cycle with a maximum mean height of about 1.8 km above ground level was observed in August, and a minimum height of about 0.7 km was observed in January. The variation in monthly mean RLH displays an obvious quarterly dependence, which coincides with the annual variation in local surface temperature.

  19. Magnetic and magnetoresistance studies of nanometric electrodeposited Co films and Co/Cu layered structures: Influence of magnetic layer thickness

    Energy Technology Data Exchange (ETDEWEB)

    Zsurzsa, S., E-mail: zsurzsa.sandor@wigner.mta.hu; Péter, L.; Kiss, L.F.; Bakonyi, I.

    2017-01-01

    The magnetic properties and the magnetoresistance behavior were investigated for electrodeposited nanoscale Co films, Co/Cu/Co sandwiches and Co/Cu multilayers with individual Co layer thicknesses ranging from 1 nm to 20 nm. The measured saturation magnetization values confirmed that the nominal and actual layer thicknesses are in fairly good agreement. All three types of layered structure exhibited anisotropic magnetoresistance for thick magnetic layers whereas the Co/Cu/Co sandwiches and Co/Cu multilayers with thinner magnetic layers exhibited giant magnetoresistance (GMR), the GMR magnitude being the largest for the thinnest Co layers. The decreasing values of the relative remanence and the coercive field when reducing the Co layer thickness down to below about 3 nm indicated the presence of superparamagnetic (SPM) regions in the magnetic layers which could be more firmly evidenced for these samples by a decomposition of the magnetoresistance vs. field curves into a ferromagnetic and an SPM contribution. For thicker magnetic layers, the dependence of the coercivity (H{sub c}) on magnetic layer thickness (d) could be described for each of the layered structure types by the usual equation H{sub c}=H{sub co}+a/d{sup n} with an exponent around n=1. The common value of n suggests a similar mechanism for the magnetization reversal by domain wall motion in all three structure types and hints also at the absence of coupling between magnetic layers in the Co/Cu/Co sandwiches and Co/Cu multilayers. - Highlights: • Electrodeposited nanoscale Co films and Co/Cu layered structures. • Co layer thickness (d) dependence of coercivity (H{sub c}) and magnetoresistance. • H{sub c} depends on Co layer thickness according to H{sub c}=H{sub co}+a/d{sup n} with n around 1. • The common n value suggests a similar mechanism of magnetization reversal. • The common n value suggests the absence of coupling between magnetic layers.

  20. Multi-layer Far-Infrared Component Technology, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This Phase I SBIR will demonstrate the feasibility of a process to create multi-layer thin-film optics for the far-infrared/sub-millimeter wave spectral region. The...

  1. A Novel Mgp-Cre Knock-In Mouse Reveals an Anticalcification/Antistiffness Candidate Gene in the Trabecular Meshwork and Peripapillary Scleral Region.

    Science.gov (United States)

    Borrás, Teresa; Smith, Matthew H; Buie, LaKisha K

    2015-04-01

    Soft tissue calcification is a pathological condition. Matrix Gla (MGP) is a potent mineralization inhibitor secreted by cartilage chondrocytes and arteries' vascular smooth muscle cells. Mgp knock-out mice die at 6 weeks due to massive arterial calcification. Arterial calcification results in arterial stiffness and higher systolic blood pressure. Intriguingly, MGP was highly abundant in trabecular meshwork (TM). Because tissue stiffness is relevant to glaucoma, we investigated which additional eye tissues use Mgp's function using knock-in mice. An Mgp-Cre-recombinase coding sequence (Cre) knock-in mouse, containing Mgp DNA plus an internal ribosomal entry site (IRES)-Cre-cassette was generated by homologous recombination. Founders were crossed with Cre-mediated reporter mouse R26R-lacZ. Their offspring expresses lacZ where Mgp is transcribed. Eyes from MgpCre/+;R26RlacZ/+ (Mgp-lacZ knock-in) and controls, 1 to 8 months were assayed for β-gal enzyme histochemistry. As expected, Mgp-lacZ knock-in's TM was intensely blue. In addition, this mouse revealed high specific expression in the sclera, particularly in the peripapillary scleral region (ppSC). Ciliary muscle and sclera above the TM were also positive. Scleral staining was located immediately underneath the choroid (chondrocyte layer), began midsclera and was remarkably high in the ppSC. Cornea, iris, lens, ciliary body, and retina were negative. All mice exhibited similar staining patterns. All controls were negative. Matrix Gla's restricted expression to glaucoma-associated tissues from anterior and posterior segments suggests its involvement in the development of the disease. Matrix Gla's anticalcification/antistiffness properties in the vascular tissue, together with its high TM and ppCS expression, place this gene as a strong candidate for TM's softness and sclera's stiffness regulation in glaucoma.

  2. Cardiac myocyte diversity and a fibroblast network in the junctional region of the zebrafish heart revealed by transmission and serial block-face scanning electron microscopy.

    Science.gov (United States)

    Lafontant, Pascal J; Behzad, Ali R; Brown, Evelyn; Landry, Paul; Hu, Norman; Burns, Alan R

    2013-01-01

    The zebrafish has emerged as an important model of heart development and regeneration. While the structural characteristics of the developing and adult zebrafish ventricle have been previously studied, little attention has been paid to the nature of the interface between the compact and spongy myocardium. Here we describe how these two distinct layers are structurally and functionally integrated. We demonstrate by transmission electron microscopy that this interface is complex and composed primarily of a junctional region occupied by collagen, as well as a population of fibroblasts that form a highly complex network. We also describe a continuum of uniquely flattened transitional cardiac myocytes that form a circumferential plate upon which the radially-oriented luminal trabeculae are anchored. In addition, we have uncovered within the transitional ring a subpopulation of markedly electron dense cardiac myocytes. At discrete intervals the transitional cardiac myocytes form contact bridges across the junctional space that are stabilized through localized desmosomes and fascia adherentes junctions with adjacent compact cardiac myocytes. Finally using serial block-face scanning electron microscopy, segmentation and volume reconstruction, we confirm the three-dimensional nature of the junctional region as well as the presence of the sheet-like fibroblast network. These ultrastructural studies demonstrate the previously unrecognized complexity with which the compact and spongy layers are structurally integrated, and provide a new basis for understanding development and regeneration in the zebrafish heart.

  3. Acoustic emission in a fluid saturated heterogeneous porous layer with application to hydraulic fracture

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, J.T. (California Univ., Berkeley, CA (USA). Dept. of Mechanical Engineering Lawrence Berkeley Lab., CA (USA))

    1988-11-01

    A theoretical model for acoustic emission in a vertically heterogeneous porous layer bounded by semi-infinite solid regions is developed using linearized equations of motion for a fluid/solid mixture and a reflectivity method. Green's functions are derived for both point loads and moments. Numerically integrated propagators represent solutions for intermediate heterogeneous layers in the porous region. These are substituted into a global matrix for solution by Gaussian elimination and back-substitution. Fluid partial stress and seismic responses to dislocations associated with fracturing of a layer of rock with a hydraulically conductive fracture network are computed with the model. A constitutive model is developed for representing the fractured rock layer as a porous material, using commonly accepted relationships for moduli. Derivations of density, tortuosity, and sinuosity are provided. The main results of the model application are the prediction of a substantial fluid partial stress response related to a second mode wave for the porous material. The response is observable for relatively large distances, on the order of several tens of meters. The visco-dynamic transition frequency associated with parabolic versus planar fluid velocity distributions across micro-crack apertures is in the low audio or seismic range, in contrast to materials with small pore size, such as porous rocks, for which the transition frequency is ultrasonic. Seismic responses are predicted for receiver locations both in the layer and in the outlying solid regions. In the porous region, the seismic response includes both shear and dilatational wave arrivals and a second-mode arrival. The second-mode arrival is not observable outside of the layer because of its low velocity relative to the dilatational and shear wave propagation velocities of the solid region.

  4. Experimental Analysis of Hydraulic Fracture Growth and Acoustic Emission Response in a Layered Formation

    Science.gov (United States)

    Ning, Li; Shicheng, Zhang; Yushi, Zou; Xinfang, Ma; Shan, Wu; Yinuo, Zhang

    2018-04-01

    Microseismic/acoustic emission (AE) monitoring is an essential technology for understanding hydraulic fracture (HF) geometry and stimulated reservoir volume (SRV) during hydraulic fracturing in unconventional reservoirs. To investigate HF growth mechanisms and features of induced microseismic/AE events in a layered formation, laboratory fracturing experiments were performed on shale specimens (30 cm × 30 cm × 30 cm) with multiple bedding planes (BPs) under triaxial stresses. AE monitoring was used to reveal the spatial distribution and hypocenter mechanisms of AE events induced by rock failure. Computerized tomography scanning was used to observe the internal fracture geometry. Experimental results showed that the various HF geometries could be obviously distinguished based on injection pressure curves and AE responses. Fracture complexity was notably increased when vertically growing HFs connected with and opened more BPs. The formation of a complex fracture network was generally indicated by frequent fluctuations in injection pressure curves, intense AE activity, and three-dimensionally distributed AE events. Investigations of the hypocenter mechanisms revealed that shear failure/event dominated in shale specimens. Shear and tensile events were induced in hydraulically connected regions, and shear events also occurred around BPs that were not hydraulically connected. This led to an overestimation of HF height and SRV in layered formations based on the AE location results. The results also showed that variable injection rate and using plugging agent were conducive in promoting HF to penetrate through the weak and high-permeability BPs, thereby increasing the fracture height.

  5. Stratigraphy of the layered terrain in Valles Marineris, Mars

    Science.gov (United States)

    Komatsu, G.; Strom, Roger G.

    1991-01-01

    The layered terrain in Valles Marineris provides information about its origin and the geologic history of this canyon system. Whether the terrain is sedimentary material deposited in a dry or lacustrine environment, or volcanic material related to the tectonics of the canyon is still controversial. However, recent studies of Gangis Layered Terrain suggests a cyclic sequence of deposition and erosion under episodic lacustrine conditions. The stratigraphic studies are extended to four other occurrences of layered terrains in Valles Marineris in an attempt to correlate and distinguish between depositional environments. The Juvantae Chasma, Hebes Chasma, Ophir and Candor Chasmata, Melas Chasma, and Gangis Layered Terrain were examined. Although there are broad similarities among the layered terrains, no two deposits are exactly alike. This suggests that there was no synchronized regional depositional processes to form all the layered deposits. However, the similar erosional style of the lower massive weakly bedded unit in Hebes, Gangis, and Ophir-Candor suggests it may have been deposited under similar circumstances.

  6. Drying of a tape-cast layer: Numerical modelling of the evaporation process in a graded/layered material

    DEFF Research Database (Denmark)

    Jabbaribehnam, Mirmasoud; Jambhekar, V. A.; Hattel, Jesper Henri

    2016-01-01

    -phase compositional porous-media flow — for the ceramic layer — and single-phase compositional laminar free flow — for the air above it. The preliminary results show the typical expected evaporation behaviour from a porous medium initially saturated with water, and water–vapour transport to the free-flow region...

  7. Adaptive optics imaging of healthy and abnormal regions of retinal nerve fiber bundles of patients with glaucoma.

    Science.gov (United States)

    Chen, Monica F; Chui, Toco Y P; Alhadeff, Paula; Rosen, Richard B; Ritch, Robert; Dubra, Alfredo; Hood, Donald C

    2015-01-08

    To better understand the nature of glaucomatous damage of the macula, especially the structural changes seen between relatively healthy and clearly abnormal (AB) retinal regions, using an adaptive optics scanning light ophthalmoscope (AO-SLO). Adaptive optics SLO images and optical coherence tomography (OCT) vertical line scans were obtained on one eye of seven glaucoma patients, with relatively deep local arcuate defects on the 10-2 visual field test in one (six eyes) or both hemifields (one eye). Based on the OCT images, the retinal nerve fiber (RNF) layer was divided into two regions: (1) within normal limits (WNL), relative RNF layer thickness within mean control values ±2 SD; and (2) AB, relative thickness less than -2 SD value. As seen on AO-SLO, the pattern of AB RNF bundles near the border of the WNL and AB regions differed across eyes. There were normal-appearing bundles in the WNL region of all eyes and AB-appearing bundles near the border with the AB region. This region with AB bundles ranged in extent from a few bundles to the entire AB region in the case of one eye. All other eyes had a large AB region without bundles. However, in two of these eyes, a few bundles were seen within this region of otherwise missing bundles. The AO-SLO images revealed details of glaucomatous damage that are difficult, if not impossible, to see with current OCT technology. Adaptive optics SLO may prove useful in following progression in clinical trials, or in disease management, if AO-SLO becomes widely available and easy to use. Copyright 2015 The Association for Research in Vision and Ophthalmology, Inc.

  8. Multilocus phylogeography of a widespread savanna-woodland-adapted rodent reveals the influence of Pleistocene geomorphology and climate change in Africa's Zambezi region.

    Science.gov (United States)

    McDonough, Molly M; Šumbera, Radim; Mazoch, Vladimír; Ferguson, Adam W; Phillips, Caleb D; Bryja, Josef

    2015-10-01

    Understanding historical influences of climate and physiographic barriers in shaping patterns of biodiversity remains limited for many regions of the world. For mammals of continental Africa, phylogeographic studies, particularly for West African lineages, implicate both geographic barriers and climate oscillations in shaping small mammal diversity. In contrast, studies for southern African species have revealed conflicting phylogenetic patterns for how mammalian lineages respond to both climate change and geologic events such as river formation, especially during the Pleistocene. However, these studies were often biased by limited geographic sampling or exclusively focused on large-bodied taxa. We exploited the broad southern African distribution of a savanna-woodland-adapted African rodent, Gerbilliscus leucogaster (bushveld gerbil) and generated mitochondrial, autosomal and sex chromosome data to quantify regional signatures of climatic and vicariant biogeographic phenomena. Results indicate the most recent common ancestor for all G. leucogaster lineages occurred during the early Pleistocene. We documented six divergent mitochondrial lineages that diverged ~0.270-0.100 mya, each of which was geographically isolated during periods characterized by alterations to the course of the Zambezi River and its tributaries as well as regional 'megadroughts'. Results demonstrate the presence of a widespread lineage exhibiting demographic expansion ~0.065-0.035 mya, a time that coincides with savanna-woodland expansion across southern Africa. A multilocus autosomal perspective revealed the influence of the Kafue River as a current barrier to gene flow and regions of secondary contact among divergent mitochondrial lineages. Our results demonstrate the importance of both climatic fluctuations and physiographic vicariance in shaping the distribution of southern African biodiversity. © 2015 John Wiley & Sons Ltd.

  9. Seasonal mixed layer heat balance of the southwestern tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Foltz, G.R.; Vialard, J.; PraveenKumar, B.; McPhaden, M.J.

    from a long-term moored buoy are used in conjunction with satellite, in situ, and atmospheric reanalysis datasets to analyze the seasonal mixed layer heat balance in the thermocline ridge region of the southwestern tropical Indian Ocean. This region...

  10. US EPA Regional Masks Web Service, US, 2015, US EPA, SEGS

    Data.gov (United States)

    U.S. Environmental Protection Agency — This web service contains the following map layers: masks and labels for EPA regions 1 through 10. Mask layers are drawn at all scales. Label layers draw at scales...

  11. Preparation and characterization of self-assembled layer by layer NiCo{sub 2}O{sub 4}–reduced graphene oxide nanocomposite with improved electrocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Manish; Elias Uddin, Md. [Advanced Materials Research Institute for BIN Fusion Technology (BK Plus Global Program), Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Singh, Jay [Department of Applied Chemistry, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110042 (India); Kim, Nam Hoon [Advanced Materials Research Institute for BIN Fusion Technology (BK Plus Global Program), Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Lee, Joong Hee, E-mail: jhl@chonbuk.ac.kr [Advanced Materials Research Institute for BIN Fusion Technology (BK Plus Global Program), Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Advanced Wind Power System Research Center, Department of Polymer and Nano Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of)

    2014-03-25

    Graphical abstract: NiCo{sub 2}O{sub 4} were grown on RGO by in situ synthesis process. FE-SEM investigation revealed self assembled layer by layer growth of NiCo{sub 2}O{sub 4}–RGO nanocomposite. NiCo{sub 2}O{sub 4}–RGO nanocomposite exhibited synergetic effect of NiCo{sub 2}O{sub 4} nanoparticles and RGO on its electrochemical performance. -- Highlights: • NiCo{sub 2}O{sub 4} were grown on RGO by in-situ synthesis process. • FE-SEM image revealed self-assembled layer by layer growth of NiCo{sub 2}O{sub 4}-RGO nanocomposite. • NiCo{sub 2}O{sub 4}-RGO nanocomposite exhibited synergetic effects on its electrochemical performance. -- Abstract: NiCo{sub 2}O{sub 4} nanoparticles dispersed on reduced graphene oxide (RGO) are prepared by simultaneously reducing graphene oxide (GO), nickel and cobalt nitrate via a hydrothermal method assisted by post annealing at low temperature. The method involves formation of hydroxides on GO using ammonia under hydrothermal conditions. Subsequent thermal treatment at 300 °C led to the conversion of hydroxides into single-phase NiCo{sub 2}O{sub 4} atop the RGO. The synthesized products are characterized through several techniques including X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The FE-SEM investigations reveal the growth of a layer by layer assembly of NiCo{sub 2}O{sub 4}–RGO (2:1) nanocomposite, where the NiCo{sub 2}O{sub 4} nanoparticles are tightly packed between the layers of RGO. Further, the catalytic properties of the NiCo{sub 2}O{sub 4}–RGO nanocomposite are investigated for the oxygen evolution reaction (OER) through cyclic voltammetry (CV) measurements. It is observed that the special structural features of the NiCo{sub 2}O{sub 4}–RGO (2:1) nanocomposite, including

  12. Initializing a Mesoscale Boundary-Layer Model with Radiosonde Observations

    Science.gov (United States)

    Berri, Guillermo J.; Bertossa, Germán

    2018-01-01

    A mesoscale boundary-layer model is used to simulate low-level regional wind fields over the La Plata River of South America, a region characterized by a strong daily cycle of land-river surface-temperature contrast and low-level circulations of sea-land breeze type. The initial and boundary conditions are defined from a limited number of local observations and the upper boundary condition is taken from the only radiosonde observations available in the region. The study considers 14 different upper boundary conditions defined from the radiosonde data at standard levels, significant levels, level of the inversion base and interpolated levels at fixed heights, all of them within the first 1500 m. The period of analysis is 1994-2008 during which eight daily observations from 13 weather stations of the region are used to validate the 24-h surface-wind forecast. The model errors are defined as the root-mean-square of relative error in wind-direction frequency distribution and mean wind speed per wind sector. Wind-direction errors are greater than wind-speed errors and show significant dispersion among the different upper boundary conditions, not present in wind speed, revealing a sensitivity to the initialization method. The wind-direction errors show a well-defined daily cycle, not evident in wind speed, with the minimum at noon and the maximum at dusk, but no systematic deterioration with time. The errors grow with the height of the upper boundary condition level, in particular wind direction, and double the errors obtained when the upper boundary condition is defined from the lower levels. The conclusion is that defining the model upper boundary condition from radiosonde data closer to the ground minimizes the low-level wind-field errors throughout the region.

  13. Exfoliation and thermal transformations of Nb-substituted layered titanates

    DEFF Research Database (Denmark)

    Song, H.; Sjåstad, Anja O.; Fjellvåg, Helmer

    2011-01-01

    Single-layer Nb-substituted titanate nanosheets of ca. 1 nm thickness were obtained by exfoliating tetrabutylammonium (TBA)-intercalated Nb-substituted titanates in water. AFM images and turbidity measurements reveal that the exfoliated nanosheets crack and corrugate when sonicated. Upon heating...... factors for increasing the transformation temperatures for conversion of the nanosheets to anatase and finally into rutile. It is further tempting to link the delay in crystallization to morphology limitations originating from the nanosheets. The present work shows that layered Nb-titanates...

  14. Perturbations in the upper layers of α Centauri A

    International Nuclear Information System (INIS)

    Brito, A; Lopes, I

    2016-01-01

    The emerging field of asteroseismology allows the direct study of stellar interiors with an incredibly high precision. We used a seismic parameter based on the phase shift as a diagnostic tool to infer the presence of a new layer of rapid variation in the external layers of the primary component of the stellar system Alpha Centauri AB. This layer is, apparently, a thin region where the acoustic modes suffer a strong scattering. Our tests indicate that this layer should be located at an acoustical depth of approximately 1400 s (0.939 R), which corresponds to a depth of 6% below the surface of the star. This is somehow unexpected since the internal structure of this sun-like star is predicted to be similar to the Sun. (paper)

  15. Object-Oriented Wavelet-Layered Digital Watermarking Technique

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-yun; YU Jue-bang; LI Ming-yu

    2005-01-01

    In this paper, an object-oriented digital watermarking technique is proposed in the wavelet domain for still images. According to the difference of recognition degree of the human eye to the different region of the image, the image is divided into the interested region and uninterested region of human eye vision in this scheme. Using the relativity of position and the difference to ocular sensitivity of the multiresolution wavelet among each subband, the image is processed with layered watermarking append technique. Experimental results show that the proposed technique successfully survives image processing operations, additive noise and JPEG compression.

  16. U-Th dating reveals regional-scale decline of branching Acropora corals on the Great Barrier Reef over the past century

    Science.gov (United States)

    Clark, Tara R.; Roff, George; Zhao, Jian-xin; Feng, Yue-xing; Done, Terence J.; McCook, Laurence J.; Pandolfi, John M.

    2017-09-01

    Hard coral cover on the Great Barrier Reef (GBR) is on a trajectory of decline. However, little is known about past coral mortality before the advent of long-term monitoring (circa 1980s). Using paleoecological analysis and high-precision uranium-thorium (U-Th) dating, we reveal an extensive loss of branching Acropora corals and changes in coral community structure in the Palm Islands region of the central GBR over the past century. In 2008, dead coral assemblages were dominated by large, branching Acropora and living coral assemblages by genera typically found in turbid inshore environments. The timing of Acropora mortality was found to be occasionally synchronous among reefs and frequently linked to discrete disturbance events, occurring in the 1920s to 1960s and again in the 1980s to 1990s. Surveys conducted in 2014 revealed low Acropora cover (shifted baseline.

  17. Community detection, link prediction, and layer interdependence in multilayer networks

    Science.gov (United States)

    De Bacco, Caterina; Power, Eleanor A.; Larremore, Daniel B.; Moore, Cristopher

    2017-04-01

    Complex systems are often characterized by distinct types of interactions between the same entities. These can be described as a multilayer network where each layer represents one type of interaction. These layers may be interdependent in complicated ways, revealing different kinds of structure in the network. In this work we present a generative model, and an efficient expectation-maximization algorithm, which allows us to perform inference tasks such as community detection and link prediction in this setting. Our model assumes overlapping communities that are common between the layers, while allowing these communities to affect each layer in a different way, including arbitrary mixtures of assortative, disassortative, or directed structure. It also gives us a mathematically principled way to define the interdependence between layers, by measuring how much information about one layer helps us predict links in another layer. In particular, this allows us to bundle layers together to compress redundant information and identify small groups of layers which suffice to predict the remaining layers accurately. We illustrate these findings by analyzing synthetic data and two real multilayer networks, one representing social support relationships among villagers in South India and the other representing shared genetic substring material between genes of the malaria parasite.

  18. Multilayer Stochastic Block Models Reveal the Multilayer Structure of Complex Networks

    Directory of Open Access Journals (Sweden)

    Toni Vallès-Català

    2016-03-01

    Full Text Available In complex systems, the network of interactions we observe between systems components is the aggregate of the interactions that occur through different mechanisms or layers. Recent studies reveal that the existence of multiple interaction layers can have a dramatic impact in the dynamical processes occurring on these systems. However, these studies assume that the interactions between systems components in each one of the layers are known, while typically for real-world systems we do not have that information. Here, we address the issue of uncovering the different interaction layers from aggregate data by introducing multilayer stochastic block models (SBMs, a generalization of single-layer SBMs that considers different mechanisms of layer aggregation. First, we find the complete probabilistic solution to the problem of finding the optimal multilayer SBM for a given aggregate-observed network. Because this solution is computationally intractable, we propose an approximation that enables us to verify that multilayer SBMs are more predictive of network structure in real-world complex systems.

  19. Bacterial Presence in Layered Rock Varnish-Possible Mars Analog?

    Science.gov (United States)

    Krinsley, D.; Rusk, B. G.

    2000-08-01

    Rock varnish from locations in Death Valley, California; Peru; Antarctica; and Hawaii reveal nanometer scale layering (less than 1 nm to about 75 nm) when studied with transmission electron microscopy (TEM). Parallel layers of clay minerals containing evidence of presumed bacteria were present in all samples. Samples range in age from a few thousand years to perhaps a million years. Diagenesis is relatively limited, as chemical composition is variable, both from top to bottom and along layers in these varnish samples. Also, occasional exotic minerals occur randomly in most varnish sections, and vary in size and hardness, again suggesting relative lack of diagenetic alteration. Additional information can be found in the original extended abstract.

  20. Spanwise vorticity and wall normal velocity structure in the inertial region of turbulent boundary layers

    Science.gov (United States)

    Cuevas Bautista, Juan Carlos; Morrill-Winter, Caleb; White, Christopher; Chini, Gregory; Klewicki, Joseph

    2017-11-01

    The Reynolds shear stress gradient is a leading order mechanism on the inertial domain of turbulent wall-flows. This quantity can be described relative to the sum of two velocity-vorticity correlations, vωz and wωy . Recent studies suggest that the first of these correlates with the step-like structure of the instantaneous streamwise velocity profile on the inertial layer. This structure is comprised of large zones of uniform momentum segregated by slender regions of concentrated vorticity. In this talk we study the contributions of the v and ωz motions to the vorticity transport (vωz) mechanism through the use of experimental data at large friction Reynolds numbers, δ+. The primary contributions to v and ωz were estimated by identifying the peak wavelengths of their streamwise spectra. The magnitudes of these peaks are of the same order, and are shown to exhibit a weak δ+ dependence. The peak wavelengths of v, however, exhibit a strong wall-distance (y) dependence, while the peak wavelengths of ωz show only a weak y dependence, and remain almost O (√{δ+}) in size throughout the inertial domain. This research was partially supported by the National Science Foundation and partially supported by the Australian Research Council.

  1. Toward Increasing Micropore Volume between Hybrid Layered Perovskites with Silsesquioxane Interlayers.

    Science.gov (United States)

    Kataoka, Sho; Kamimura, Yoshihiro; Endo, Akira

    2018-04-10

    Hybrid organic-inorganic layered perovskites are typically nonporous solids. However, the incorporation of silsesquioxanes with a cubic cage structure as interlayer materials creates micropores between the perovskite layers. In this study, we increase in the micropore volume in layered perovskites by replacing a portion of the silsesquioxane interlayers with organic amines. In the proposed method, approximately 20% of the silsesquioxane interlayers can be replaced without changing the layer distance owing to the size of the silsesquioxane. When small amines (e.g., ethylamine) are used in this manner, the micropore volume of the obtained hybrid layered perovskites increases by as much as 44%; when large amines (e.g., phenethylamine) are used, their micropore volume decreases by as much as 43%. Through the variation of amine fraction, the micropore volume can be adjusted in the range. Finally, the magnetic moment measurements reveal that the layered perovskites with mixed interlayers exhibit ferromagnetic ordering at temperature below 20 K, thus indicating that the obtained perovskites maintain their functions as layered perovskites.

  2. Interstratified nanohybrid assembled by alternating cationic layered double hydroxide nanosheets and anionic layered titanate nanosheets with superior photocatalytic activity

    International Nuclear Information System (INIS)

    Lin, Bizhou; Sun, Ping; Zhou, Yi; Jiang, Shaofeng; Gao, Bifen; Chen, Yilin

    2014-01-01

    Graphical abstract: - Highlights: • Two kinds of nanosheets are well arranged in a layer-by-layer alternating fashion. • Effective interfacial heterojunction and high specific surface were observed. • Interstratified nanohybrid exhibits a superior photocatalytic activity. - Abstract: Oppositely charged 2D inorganic nanosheets of ZnAl-layered double hydroxide and layered titanate were successfully assembled into an interstratified nanohybrid through simply mixing the corresponding nanosheet suspensions. Powder X-ray diffraction and high-resolution transmission electron microscope clearly revealed that the component nanosheets in the as-obtained nanohybrid ZnAl–Ti 3 O 7 retain the 2D sheet skeletons of the pristine materials and that the two kinds of nanosheets are well arranged in a layer-by-layer alternating fashion with a basal spacing of about 1.3 nm, coincident with the thickness summation of the two component nanosheets. The effective interfacial heterojunction between them and the high specific surface area resulted in that the nanohybrid exhibits a superior photocatalytic activity in the degradation of methylene blue with a reaction constant k of 2.81 × 10 −2 min −1 , which is about 9 and 4 times higher than its precursors H 2 Ti 3 O 7 and ZnAl-LDH, respectively. Based on UV–vis, XPS and photoelectrochemical measurements, a proposed photoexcitation model was provided to understand its photocatalytic behavior

  3. Characteristics of Boundary Layer Structure during a Persistent Haze Event in the Central Liaoning City Cluster, Northeast China

    Science.gov (United States)

    Li, Xiaolan; Wang, Yangfeng; Shen, Lidu; Zhang, Hongsheng; Zhao, Hujia; Zhang, Yunhai; Ma, Yanjun

    2018-04-01

    The characteristics of boundary layer structure during a persistent regional haze event over the central Liaoning city cluster of Northeast China from 16 to 21 December 2016 were investigated based on the measurements of particulate matter (PM) concentration and the meteorological data within the atmospheric boundary layer (ABL). During the observational period, the maximum hourly mean PM2.5 and PM10 concentrations in Shenyang, Anshan, Fushun, and Benxi ranged from 276 to 355 μg m-3 and from 378 to 442 μg m-3, respectively, and the lowest hourly mean atmospheric visibility (VIS) in different cities ranged from 0.14 to 0.64 km. The central Liaoning city cluster was located in the front of a slowly moving high pressure and was mainly controlled by southerly winds. Wind speed (WS) within the ABL (pollutants. A potential temperature inversion layer existed throughout the entire ABL during the earlier hazy episode [from 0500 Local Time (LT) 18 December to 1100 LT 19 December], and then a potential temperature inversion layer developed with the bottom gradually decreased from 900 m to 300 m. Such a stable atmospheric stratification further weakened pollutant dispersion. The atmospheric boundary layer height (ABLH) estimated based on potential temperature profiles was mostly lower than 400 m and varied oppositely with PM2.5 in Shenyang. In summary, weak winds due to calm synoptic conditions, strong thermal inversion layer, and shallow atmospheric boundary layer contributed to the formation and development of this haze event. The backward trajectory analysis revealed the sources of air masses and explained the different characteristics of the haze episodes in the four cities.

  4. Multiscale investigation of graphene layers on 6H-SiC(000-1)

    OpenAIRE

    Tiberj, Antoine; Huntzinger, Jean-Roch; Camassel, Jean; Hiebel, Fanny; Mahmood, Ather; Mallet, Pierre; Naud, Cecile; Veuillen, Jean-Yves

    2011-01-01

    Abstract In this article, a multiscale investigation of few graphene layers grown on 6H-SiC(000-1) under ultrahigh vacuum (UHV) conditions is presented. At 100-μm scale, the authors show that the UHV growth yields few layer graphene (FLG) with an average thickness given by Auger spectroscopy between 1 and 2 graphene planes. At the same scale, electron diffraction reveals a significant rotational disorder between the first graphene layer and the SiC surface, although well-defined preferre...

  5. X-ray and scanning electron microscopic investigation of porous silicon and silicon epitaxial layers grown on porous silicon

    International Nuclear Information System (INIS)

    Wierzchowski, W.; Pawlowska, M.; Nossarzewska-Orlowska, E.; Brzozowski, A.; Wieteska, K.; Graeff, W.

    1998-01-01

    The 1 to 5 μm thick layers of porous silicon and epitaxial layers grown on porous silicon were studied by means of X-ray diffraction methods, realised with a wide use of synchrotron source and scanning microscopy. The results of x-ray investigation pointed the difference of lateral periodicity between the porous layer and the substrate. It was also found that the deposition of epitaxial layer considerably reduced the coherence of porous fragments. A number of interface phenomena was also observed in section and plane wave topographs. The scanning electron microscopic investigation of cleavage faces enabled direct evaluation of porous layer thickness and revealed some details of their morphology. The scanning observation of etched surfaces of epitaxial layers deposited on porous silicon revealed dislocations and other defects not reasonable in the X-ray topographs. (author)

  6. Layering and Ordering in Electrochemical Double Layers

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yihua [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States; Kawaguchi, Tomoya [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States; Pierce, Michael S. [Rochester Institute of Technology, School of Physics and Astronomy, Rochester, New York 14623, United States; Komanicky, Vladimir [Faculty of Science, Safarik University, 041 54 Kosice, Slovakia; You, Hoydoo [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States

    2018-02-26

    Electrochemical double layers (EDL) form at electrified interfaces. While Gouy-Chapman model describes moderately charged EDL, formation of Stern layers was predicted for highly charged EDL. Our results provide structural evidence for a Stern layer of cations, at potentials close to hydrogen evolution in alkali fluoride and chloride electrolytes. Layering was observed by x-ray crystal truncation rods and atomic-scale recoil responses of Pt(111) surface layers. Ordering in the layer is confirmed by glancing-incidence in-plane diffraction measurements.

  7. Convection Study by PIV Method Within Horizontal Liquid Layer Evaporating Into Inert Gas Flow

    Directory of Open Access Journals (Sweden)

    Kreta Aleksei

    2016-01-01

    Full Text Available The paper is devoted to the experimental study of convection in a horizontal evaporating liquid layer (ethanol of limited size under the action of gas flow (air. The two-dimensional velocity field in the liquid layer is obtained using the PIV method. The existence of a vortex convective flow within a liquid layer directed towards the gas flow has been revealed.

  8. Enhancement of absorption in vertically-oriented graphene sheets growing on a thin copper layer

    Energy Technology Data Exchange (ETDEWEB)

    Rozouvan, Tamara; Poperenko, Leonid [Taras Shevchenko National University of Kyiv, Department of Physics 4, Prospect Glushkova, Kyiv, 03187 (Ukraine); Kravets, Vasyl, E-mail: vasyl_kravets@yahoo.com [School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL (United Kingdom); Shaykevich, Igor [Taras Shevchenko National University of Kyiv, Department of Physics 4, Prospect Glushkova, Kyiv, 03187 (Ukraine)

    2017-02-28

    Highlights: • The optical properties and surface structure of graphene films. • Chemical vapour deposition method. • Scanning tunneling microscopy revealed vertical crystal lattice structure of graphene layer. • We report a significant enhancement of the absorption band in the vertically-oriented graphene sheets. - Abstract: The optical properties and surface structure of graphene films grown on thin copper Cu (1 μm) layer using chemical vapour deposition method were investigated via spectroscopic ellipsometry and nanoscopic measurements. Angle variable ellipsometry measurements were performed to analyze the features of dispersion of the complex refractive index and optical conductivity. It was observed significant enhancement of the absorption band in the vertically-oriented graphene sheets layer with respect to the bulk graphite due to interaction between excited localized surface plasmon at surface of thin Cu layer and graphene’s electrons. Scanning tunneling microscopy measurements with atomic spatial resolution revealed vertical crystal lattice structure of the deposited graphene layer. The obtained results provide direct evidence of the strong influence of the growing condition and morphology of nanostructure on electronic and optical behaviours of graphene film.

  9. Fabrication of anticorrosive multilayer onto magnesium alloy substrates via spin-assisted layer-by-layer technique

    Energy Technology Data Exchange (ETDEWEB)

    Cai Kaiyong, E-mail: Kaiyong_cai@cqu.edu.cn [Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); Sui Xiaojing; Hu Yan [Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); Zhao Li [China National Centre for Biotechnology Development, No. 16, Xi Si Huan Zhong Lu, Haidian District, Beijing 100036 (China); Lai Min; Luo Zhong; Liu Peng; Yang Weihu [Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China)

    2011-12-01

    To improve the corrosion resistance of magnesium alloy, we reported a novel approach for the fabrication of anticorrosive multilayers onto AZ91D substrates. The multilayers were composed of poly(ethylene imine) (PEI), poly(styrene sulfonate) (PSS) and 8-hydroxyquinoline (8HQ). They were deposited onto AZ91D substrates via a spin-assisted layer-by-layer (LbL) technique. The multilayered structure was stabilized with glutaraldehyde (GA) as crossing linker. It was confirmed by Fourier transform infrared spectroscopy (FT-IR). Surface morphologies and elemental compositions of the formed anticorrosive multilayers were characterized with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. The corrosion performance of the multilayer coated AZ91D substrates was characterized by hydrogen evolution. The results of electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements suggested that the multilayered coating improved the corrosion resistance of AZ91D substrates. In vitro study revealed that the multilayered coating was cytocompatible. The study provides a potential alternative for the fabrication of corrosion resistant magnesium alloy-based implants. Highlights: {yields} Corrosion protective multilayers have been constructed onto AZ91D substrates via layer by layer technique. {yields} The multilayered structured containing 8-hydroxyquinoline highly improves the corrosion resistance of AZ91D substrates. {yields} The novel multilayered coating is potentially important for developing corrosion resistant magnesium alloy-based implants.

  10. Fabrication of anticorrosive multilayer onto magnesium alloy substrates via spin-assisted layer-by-layer technique

    International Nuclear Information System (INIS)

    Cai Kaiyong; Sui Xiaojing; Hu Yan; Zhao Li; Lai Min; Luo Zhong; Liu Peng; Yang Weihu

    2011-01-01

    To improve the corrosion resistance of magnesium alloy, we reported a novel approach for the fabrication of anticorrosive multilayers onto AZ91D substrates. The multilayers were composed of poly(ethylene imine) (PEI), poly(styrene sulfonate) (PSS) and 8-hydroxyquinoline (8HQ). They were deposited onto AZ91D substrates via a spin-assisted layer-by-layer (LbL) technique. The multilayered structure was stabilized with glutaraldehyde (GA) as crossing linker. It was confirmed by Fourier transform infrared spectroscopy (FT-IR). Surface morphologies and elemental compositions of the formed anticorrosive multilayers were characterized with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. The corrosion performance of the multilayer coated AZ91D substrates was characterized by hydrogen evolution. The results of electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements suggested that the multilayered coating improved the corrosion resistance of AZ91D substrates. In vitro study revealed that the multilayered coating was cytocompatible. The study provides a potential alternative for the fabrication of corrosion resistant magnesium alloy-based implants. Highlights: → Corrosion protective multilayers have been constructed onto AZ91D substrates via layer by layer technique. → The multilayered structured containing 8-hydroxyquinoline highly improves the corrosion resistance of AZ91D substrates. → The novel multilayered coating is potentially important for developing corrosion resistant magnesium alloy-based implants.

  11. Evaluation of a thin-layer chromatographic technique for ...

    African Journals Online (AJOL)

    Methanol extracts of both fistula and bush samples were prepared and analysed by thin-layer chromatography. Chromatoplates, when visualised under ultraviolet light, revealed a number of fluorescent compounds, some of which were common in both the fistula and bush sample extracts. By comparing the presence of ...

  12. Tunable UV-visible absorption of SnS2 layered quantum dots produced by liquid phase exfoliation.

    Science.gov (United States)

    Fu, Xiao; Ilanchezhiyan, P; Mohan Kumar, G; Cho, Hak Dong; Zhang, Lei; Chan, A Sattar; Lee, Dong J; Panin, Gennady N; Kang, Tae Won

    2017-02-02

    4H-SnS 2 layered crystals synthesized by a hydrothermal method were used to obtain via liquid phase exfoliation quantum dots (QDs), consisting of a single layer (SLQDs) or multiple layers (MLQDs). Systematic downshift of the peaks in the Raman spectra of crystals with a decrease in size was observed. The bandgap of layered QDs, estimated by UV-visible absorption spectroscopy and the tunneling current measurements using graphene probes, increases from 2.25 eV to 3.50 eV with decreasing size. 2-4 nm SLQDs, which are transparent in the visible region, show selective absorption and photosensitivity at wavelengths in the ultraviolet region of the spectrum while larger MLQDs (5-90 nm) exhibit a broad band absorption in the visible spectral region and the photoresponse under white light. The results show that the layered quantum dots obtained by liquid phase exfoliation exhibit well-controlled and regulated bandgap absorption in a wide tunable wavelength range. These novel layered quantum dots prepared using an inexpensive method of exfoliation and deposition from solution onto various substrates at room temperature can be used to create highly efficient visible-blind ultraviolet photodetectors and multiple bandgap solar cells.

  13. Formation of an Anti-Core–Shell Structure in Layered Oxide Cathodes for Li-Ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hanlei [Materials; amp, Department; NorthEast; Omenya, Fredrick [NorthEast; Whittingham, M. Stanley [NorthEast; Wang, Chongmin [Environmental; Zhou, Guangwen [Materials; amp, Department; NorthEast

    2017-10-20

    The layered → rock-salt phase transformation in the layered dioxide cathodes for Li-ion batteries is believed to result in a “core-shell” structure of the primary particles, in which the core region maintains as the layered phase while the surface region undergoes the phase transformation to the rock-salt phase. Using transmission electron microscopy, here we demonstrate the formation of an “anti-core-shell” structure in cycled primary particles with a formula of LiNi0.80Co0.15Al0.05O2, in which the surface and subsurface regions remain as the layered structure while the rock-salt phase forms as domains in the bulk with a thin layer of the spinel phase between the rock-salt core and the skin of the layered phase. Formation of this anti-core-shell structure is attributed to the oxygen loss at the surface that drives the migration of oxygen from the bulk to the surface, thereby resulting in localized areas of significantly reduced oxygen levels in the bulk of the particle, which subsequently undergoes the phase transformation to the rock-salt domains. The formation of the anti-core-shell rock-salt domains is responsible for the reduced capacity, discharge voltage and ionic conductivity in cycled cathode.

  14. Prevention of intra-abdominal adhesion by bi-layer electrospun membrane.

    Science.gov (United States)

    Jiang, Shichao; Wang, Wei; Yan, Hede; Fan, Cunyi

    2013-06-04

    The aim of this study was to compare the anti-adhesion efficacy of a bi-layer electrospun fibrous membrane consisting of hyaluronic acid-loaded poly(ε-caprolactone) (PCL) fibrous membrane as the inner layer and PCL fibrous membrane as the outer layer with a single-layer PCL electrospun fibrous membrane in a rat cecum abrasion model. The rat model utilized a cecal abrasion and abdominal wall insult surgical protocol. The bi-layer and PCL membranes were applied between the cecum and the abdominal wall, respectively. Control animals did not receive any treatment. After postoperative day 14, a visual semiquantitative grading scale was used to grade the extent of adhesion. Histological analysis was performed to reveal the features of adhesion tissues. Bi-layer membrane treated animals showed significantly lower adhesion scores than control animals (p compared with the PCL membrane. Histological analysis of the bi-layer membrane treated rat rarely demonstrated tissue adhesion while that of the PCL membrane treated rat and control rat showed loose and dense adhesion tissues, respectively. Bi-layer membrane can efficiently prevent adhesion formation in abdominal cavity and showed a significantly decreased adhesion tissue formation compared with the control.

  15. Hypodense regions (holes) in the retinal nerve fiber layer in frequency-domain OCT scans of glaucoma patients and suspects.

    Science.gov (United States)

    Xin, Daiyan; Talamini, Christine L; Raza, Ali S; de Moraes, Carlos Gustavo V; Greenstein, Vivienne C; Liebmann, Jeffrey M; Ritch, Robert; Hood, Donald C

    2011-09-09

    To better understand hypodense regions (holes) that appear in the retinal nerve fiber layer (RNFL) of frequency-domain optical coherence tomography (fdOCT) scans of patients with glaucoma and glaucoma suspects. Peripapillary circle (1.7-mm radius) and cube optic disc fdOCT scans were obtained on 208 eyes from 110 patients (57.4 ± 13.2 years) with glaucomatous optic neuropathy (GON) and 45 eyes of 45 controls (48.0 ± 12.6 years) with normal results of fundus examination. Holes in the RNFL were identified independently by two observers on the circle scans. Holes were found in 33 (16%) eyes of 28 (25%) patients; they were not found in any of the control eyes. Twenty-four eyes had more than one hole. Although some holes were relatively large, others were small. In general, the holes were located adjacent to blood vessels; only three eyes had isolated holes that were not adjacent to a vessel. The holes tended to be in the regions that are thickest in healthy controls and were associated with arcuate defects in patients. Holes were not seen in the center of the temporal disc region. They were more common in the superior (25 eyes) than in the inferior (15 eyes) disc. Of the 30 eyes with holes with reliable visual fields, seven were glaucoma suspect eyes with normal visual fields. The holes in the RNFL seen in patients with GON were probably due to a local loss of RNFL fibers and can occur in the eyes of glaucoma suspects with normal visual fields.

  16. GePb Alloy Growth Using Layer Inversion Method

    Science.gov (United States)

    Alahmad, Hakimah; Mosleh, Aboozar; Alher, Murtadha; Banihashemian, Seyedeh Fahimeh; Ghetmiri, Seyed Amir; Al-Kabi, Sattar; Du, Wei; Li, Bauhoa; Yu, Shui-Qing; Naseem, Hameed A.

    2018-04-01

    Germanium-lead films have been investigated as a new direct-bandgap group IV alloy. GePb films were deposited on Si via thermal evaporation of Ge and Pb solid sources using the layer inversion metal-induced crystallization method for comparison with the current laser-induced recrystallization method. Material characterization of the films using x-ray diffraction analysis revealed highly oriented crystallinity and Pb incorporation as high as 13.5% before and 5.2% after annealing. Transmission electron microscopy, scanning electron microscopy, and energy-dispersive x-ray mapping of the samples revealed uniform incorporation of elements and complete layer inversion. Optical characterization of the GePb films by Raman spectroscopy and photoluminescence techniques showed that annealing the samples resulted in higher crystalline quality as well as bandgap reduction. The bandgap reduction from 0.67 eV to 0.547 eV observed for the highest-quality material confirms the achievement of a direct-bandgap material.

  17. GePb Alloy Growth Using Layer Inversion Method

    Science.gov (United States)

    Alahmad, Hakimah; Mosleh, Aboozar; Alher, Murtadha; Banihashemian, Seyedeh Fahimeh; Ghetmiri, Seyed Amir; Al-Kabi, Sattar; Du, Wei; Li, Bauhoa; Yu, Shui-Qing; Naseem, Hameed A.

    2018-07-01

    Germanium-lead films have been investigated as a new direct-bandgap group IV alloy. GePb films were deposited on Si via thermal evaporation of Ge and Pb solid sources using the layer inversion metal-induced crystallization method for comparison with the current laser-induced recrystallization method. Material characterization of the films using x-ray diffraction analysis revealed highly oriented crystallinity and Pb incorporation as high as 13.5% before and 5.2% after annealing. Transmission electron microscopy, scanning electron microscopy, and energy-dispersive x-ray mapping of the samples revealed uniform incorporation of elements and complete layer inversion. Optical characterization of the GePb films by Raman spectroscopy and photoluminescence techniques showed that annealing the samples resulted in higher crystalline quality as well as bandgap reduction. The bandgap reduction from 0.67 eV to 0.547 eV observed for the highest-quality material confirms the achievement of a direct-bandgap material.

  18. Characterization of focal cortical dysplasia with balloon cells by layer-specific markers: Evidence for differential vulnerability of interneurons.

    Science.gov (United States)

    Nakagawa, Julia M; Donkels, Catharina; Fauser, Susanne; Schulze-Bonhage, Andreas; Prinz, Marco; Zentner, Josef; Haas, Carola A

    2017-04-01

    Focal cortical dysplasia (FCD) is a major cause of pharmacoresistant focal epilepsy. Little is known about the pathomechanisms underlying the characteristic cytoarchitectural abnormalities associated with FCD. In the present study, a broad panel of markers identifying layer-specific neuron subpopulations was applied to characterize dyslamination and structural alterations in FCD with balloon cells (FCD 2b). Pan-neuronal neuronal nuclei (NeuN) and layer-specific protein expression (Reelin, Calbindin, Calretinin, SMI32 (nonphosphorylated neurofilament H), Parvalbumin, transducin-like enhancer protein 4 (TLE4), and Vimentin) was studied by immunohistochemistry on paraffin sections of FCD2b cases (n = 22) and was compared to two control groups with (n = 7) or without epilepsy (n = 4 postmortem cases). Total and layer-specific neuron densities were systematically quantified by cell counting considering age at surgery and brain region. We show that in FCD2b total neuron densities across all six cortical layers were not significantly different from controls. In addition, we present evidence that a basic laminar arrangement of layer-specific neuron subtypes was preserved despite the severe disturbance of cortical structure. SMI32-positive pyramidal neurons showed no significant difference in total numbers, but a reduction in layers III and V. The densities of supragranular Calbindin- and Calretinin-positive interneurons in layers II and III were not different from controls, whereas Parvalbumin-expressing interneurons, primarily located in layer IV, were significantly reduced in numbers when compared to control cases without epilepsy. In layer VI, the density of TLE4-positive projection neurons was significantly increased. Altogether, these data show that changes in cellular composition mainly affect deep cortical layers in FCD2b. The application of a broad panel of markers defining layer-specific neuronal subpopulations revealed that in FCD2b neuronal diversity and a basic

  19. Characterization and use of crystalline bacterial cell surface layers

    Science.gov (United States)

    Sleytr, Uwe B.; Sára, Margit; Pum, Dietmar; Schuster, Bernhard

    2001-10-01

    Crystalline bacterial cell surface layers (S-layers) are one of the most common outermost cell envelope components of prokaryotic organisms (archaea and bacteria). S-layers are monomolecular arrays composed of a single protein or glycoprotein species and represent the simplest biological membranes developed during evolution. S-layers as the most abundant of prokaryotic cellular proteins are appealing model systems for studying the structure, synthesis, genetics, assembly and function of proteinaceous supramolecular structures. The wealth of information existing on the general principle of S-layers have revealed a broad application potential. The most relevant features exploited in applied S-layer research are: (i) pores passing through S-layers show identical size and morphology and are in the range of ultrafiltration membranes; (ii) functional groups on the surface and in the pores are aligned in well-defined positions and orientations and accessible for chemical modifications and binding functional molecules in very precise fashion; (iii) isolated S-layer subunits from a variety of organisms are capable of recrystallizing as closed monolayers onto solid supports (e.g., metals, polymers, silicon wafers) at the air-water interface, on lipid films or onto the surface of liposomes; (iv) functional domains can be incorporated in S-layer proteins by genetic engineering. Thus, S-layer technologies particularly provide new approaches for biotechnology, biomimetics, molecular nanotechnology, nanopatterning of surfaces and formation of ordered arrays of metal clusters or nanoparticles as required for nanoelectronics.

  20. Hydrodynamics of layer structured targets impinged by intense ion beams

    International Nuclear Information System (INIS)

    Davila, J.; Barrero, A.

    1989-01-01

    To minimize the energy loss in the corona outflow, a layer structured spherical hollow shell has been proposed to be used as target in inertial confinement fusion. For ion beam drivers, the major part of the beam energy is absorbed in the middle layer, which is called either absorber or pusher. The outer layer, called tamper, slows down the outward expansion of the absorbed low density region. The materials of the tamper and pusher are usually in the inner layer. The knowledge of the hydrodynamics of the interaction of an intense beam with a structured target is then an essential point in order to achieve break-even conditions in ion-beam fusion. (author) 2 refs., 2 figs

  1. Topside ionosphere of Mars: Variability, transient layers, and the role of crustal magnetic fields

    Science.gov (United States)

    Gopika, P. G.; Venkateswara Rao, N.

    2018-04-01

    The topside ionosphere of Mars is known to show variability and transient topside layers. In this study, we analyzed the electron density profiles measured by the radio occultation technique aboard the Mars Global Surveyor spacecraft to study the topside ionosphere of Mars. The electron density profiles that we used in the present study span between 1998 and 2005. All the measurements are done from the northern high latitudes, except 220 profiles which were measured in the southern hemisphere, where strong crustal magnetic fields are present. We binned the observations into six measurement periods: 1998, 1999-north, 1999-south, 2000-2001, 2002-2003, and 2004-2005. We found that the topside ionosphere in the southern high latitudes is more variable than that from the northern hemisphere. This feature is clearly seen with fluctuations of wavelengths less than 20 km. Some of the electron density profiles show a transient topside layer with a local maximum in electron density between 160 km and 210 km. The topside layer is more prone to occur in the southern hemispheric crustal magnetic field regions than in the other regions. In addition, the peak density of the topside layer is greater in regions of strong crustal magnetic fields than in other regions. The variability of the topside ionosphere and the peak density of the topside layer, however, do not show one-to-one correlation with the strength of the crustal magnetic fields and magnetic field inclination. The results of the present study are discussed in the light of current understanding on the topside ionosphere, transient topside layers, and the role of crustal magnetic fields on plasma motions.

  2. A high-latitude, low-latitude boundary layer model of the convection current system

    International Nuclear Information System (INIS)

    Siscoe, G.L.; Lotko, W.; Sonnerup, B.U.O.

    1991-01-01

    Observations suggest that both the high- and low-latitude boundary layers contribute to magnetospheric convection, and that their contributions are linked. In the interpretation pursued here, the high-latitude boundary layer (HBL) generates the voltage while the low-latitude boundary layer (LBL) generates the current for the part of the convection electric circuit that closes through the ionosphere. This paper gives a model that joins the high- and low-latitude boundary layers consistently with the ionospheric Ohm's law. It describes an electric circuit linking both boundary layers, the region 1 Birkeland currents, and the ionospheric Pedersen closure currents. The model works by using the convection electric field that the ionosphere receives from the HBL to determine two boundary conditions to the equations that govern viscous LBL-ionosphere coupling. The result provides the needed self-consistent coupling between the two boundary layers and fully specifies the solution for the viscous LBL-ionosphere coupling equations. The solution shows that in providing the current required by the ionospheric Ohm's law, the LBL needs only a tenth of the voltage that spans the HBL. The solution also gives the latitude profiles of the ionospheric electric field, parallel currents, and parallel potential. It predicts that the plasma in the inner part of the LBL moves sunward instead of antisunward and that, as the transpolar potential decreases below about 40 kV, reverse polarity (region 0) currents appear at the poleward border of the region 1 currents. A possible problem with the model is its prediction of a thin boundary layer (∼1000 km), whereas thicknesses inferred from satellite data tend to be greater

  3. Structure of reconnection boundary layers in incompressible MHD

    International Nuclear Information System (INIS)

    Sonnerup, B.U.Oe.; Wang, D.J.

    1987-01-01

    The incompressible MHD equations with nonvanishing viscosity and resistivity are simplified by use of the boundary layer approximation to describe the flow and magnetic field in the exit flow regions of magnetic field reconnection configurations when the reconnection rate is small. The conditions are derived under which self-similar solutions exist of the resulting boundary layer equations. For the case of zero viscosity and resistivity, the equations describing such self-similar layers are then solved in terms of quadratures, and the resulting flow and field configurations are described. Symmetric solutions, relevant, for example, to reconnection in the geomagnetic tail, as well as asymmetric solutions, relevant to reconnection at the earth's magnetopause, are found to exist. The nature of the external solutions to which the boundary layer solutions should be matched is discussed briefly, but the actual matching, which is to occur at Alfven-wave characteristic curves in the boundary layer solutions, is not carried out. Finally, it is argued that the solutions obtained may also be used to describe the structure of the intense vortex layers observed to occur at magnetic separatrices in computer simulations and in certain analytical models of the reconnection process

  4. Non-destructive testing of layer-to-layer fusion of a 3D print using ultrahigh resolution optical coherence tomography

    DEFF Research Database (Denmark)

    Israelsen, Niels Møller; Maria, Michael; Feuchter, Thomas

    2017-01-01

    Within the last decade, 3D printing has moved from a costly approach of building mechanical items to the present state-of-the-art phase where access to 3D printers is now common, both in industry and in private places. The plastic printers are the most common type of 3D printers providing prints...... on volume imaging of a 3D printed block made with 100% PLA fill. By employing ultrahigh resolution OCT (UHR-OCT) we show that some parts of the PLA volume reveal highly scattering interfaces which likely correspond to transitions from one layer to another. In doing so, we document that UHR-OCT can act...... as a powerful tool that can be used in detecting fractures between layers stemming from insufficient fusion between printed structure layers. UHR-OCT can therefore serve as an useful assessment method of quality of 3D prints....

  5. Reactive mesogen photoalignment on photopolymerizable composite layer

    International Nuclear Information System (INIS)

    Mahilny, U V; Stankevich, A I; Trofimova, A V

    2016-01-01

    The volume photoanisotropy (photoinduced birefringence) and surface photoanisotropy (LC photoalignment) of compositions of LC monomer - benzaldehyde polymer upon polarized UV radiation have been revealed and investigated. A high quality of photoalignment is confirmed by an extreme value of birefringence and low imperfection of phase plates fabricated on the basis of LC monomer on composite layer. (paper)

  6. Deformation behavior of sintered nanocrystalline silver layers

    International Nuclear Information System (INIS)

    Zabihzadeh, S.; Van Petegem, S.; Duarte, L.I.; Mokso, R.; Cervellino, A.; Van Swygenhoven, H.

    2015-01-01

    The microstructure of porous silver layers produced under different low temperature pressure-assisted sintering conditions is characterized and linked with the mechanical behavior studied in situ during X-ray diffraction. Peak profile analysis reveals important strain recovery and hardening mechanism during cyclic deformation. The competition between both mechanisms is discussed in terms of porosity and grain size

  7. Chemical storage of hydrogen in few-layer graphene

    Science.gov (United States)

    Subrahmanyam, K. S.; Kumar, Prashant; Maitra, Urmimala; Govindaraj, A.; Hembram, K. P. S. S.; Waghmare, Umesh V.; Rao, C. N. R.

    2011-01-01

    Birch reduction of few-layer graphene samples gives rise to hydrogenated samples containing up to 5 wt % of hydrogen. Spectroscopic studies reveal the presence of sp3 C-H bonds in the hydrogenated graphenes. They, however, decompose readily on heating to 500 °C or on irradiation with UV or laser radiation releasing all the hydrogen, thereby demonstrating the possible use of few-layer graphene for chemical storage of hydrogen. First-principles calculations throw light on the mechanism of dehydrogenation that appears to involve a significant reconstruction and relaxation of the lattice. PMID:21282617

  8. Excimer laser annealing of shallow As and B doped layers

    International Nuclear Information System (INIS)

    Monakhov, E.V.; Svensson, B.G.; Linnarsson, M.K.; Magna, A. La; Privitera, V.; Camalleri, M.; Fortunato, G.; Mariucci, L.

    2004-01-01

    Excimer laser annealing (ELA) of As-, B- and BF 2 -implanted Si has been studied by secondary ion mass spectrometry (SIMS), spreading resistance probe (SRP) and transmission electron microscopy (TEM). The implantations have been performed in the energy range from 1 to 30 keV with doses of 10 15 -10 16 cm -2 . ELA has been carried out with the energy densities in the range of 600-1200 mJ/cm 2 and the number of laser pulses from 1 to 10. It is shown that ELA results in a more uniform dopant distribution over the doped region with a more abrupt profile edge as compared to those after rapid thermal annealing (RTA). Besides, in contrast to RTA, ELA demonstrates a highly confined annealing effect, where the distribution of dopants below the melting region is not affected. SRP measurements demonstrate almost complete activation of the implanted dopants after ELA, and TEM does not reveal extended defects in the ELA-treated samples. The depth of the doped layers, abruptness of the profiles and the total doping dose as a function of ELA energy density and number of laser pulses are investigated. Computer simulations of ELA show a good agreement with the experimental data

  9. Regional Atmospheric CO2 Inversion Reveals Seasonal and Geographic Differences in Amazon Net Biome Exchange

    Science.gov (United States)

    Alden, Caroline B.; Miller, John B.; Gatti, Luciana V.; Gloor, Manuel M.; Guan, Kaiyu; Michalak, Anna M.; van der Laan-Luijkx, Ingrid; Touma, Danielle; Andrews, Arlyn; Basso, Luana G.; hide

    2016-01-01

    Understanding tropical rainforest carbon exchange and its response to heat and drought is critical for quantifying the effects of climate change on tropical ecosystems, including global climate carbon feedbacks. Of particular importance for the global carbon budget is net biome exchange of CO2 with the atmosphere (NBE), which represents nonfire carbon fluxes into and out of biomass and soils. Subannual and sub-Basin Amazon NBE estimates have relied heavily on process-based biosphere models, despite lack of model agreement with plot-scale observations. We present a new analysis of airborne measurements that reveals monthly, regional-scale (Approx.1-8 x 10(exp -6) km2) NBE variations. We develop a regional atmospheric CO2 inversion that provides the first analysis of geographic and temporal variability in Amazon biosphere-atmosphere carbon exchange and that is minimally influenced by biosphere model-based first guesses of seasonal and annual mean fluxes. We find little evidence for a clear seasonal cycle in Amazon NBE but do find NBE sensitivity to aberrations from long-term mean climate. In particular, we observe increased NBE (more carbon emitted to the atmosphere) associated with heat and drought in 2010, and correlations between wet season NBE and precipitation (negative correlation) and temperature (positive correlation). In the eastern Amazon, pulses of increased NBE persisted through 2011, suggesting legacy effects of 2010 heat and drought. We also identify regional differences in postdrought NBE that appear related to long-term water availability. We examine satellite proxies and find evidence for higher gross primary productivity (GPP) during a pulse of increased carbon uptake in 2011, and lower GPP during a period of increased NBE in the 2010 dry season drought, but links between GPP and NBE changes are not conclusive. These results provide novel evidence of NBE sensitivity to short-term temperature and moisture extremes in the Amazon, where monthly and sub

  10. Numerical modelling of the atmospheric mixing-layer diurnal evolution

    International Nuclear Information System (INIS)

    Molnary, L. de.

    1990-03-01

    This paper introduce a numeric procedure to determine the temporal evolution of the height, potential temperature and mixing ratio in the atmospheric mixing layer. The time and spatial derivatives were evaluated via forward in time scheme to predict the local evolution of the mixing-layer parameters, and a forward in time, upstream in space scheme to predict the evolution of the mixing-layer over a flat region with a one-dimensional advection component. The surface turbulent fluxes of sensible and latent heat were expressed using a simple sine wave that is function of the hour day and kind of the surface (water or country). (author) [pt

  11. Axisymmetric flow in a cylindrical tank over a rotating bottom. Part I. Analysis of boundary layers and vertical circulation

    Energy Technology Data Exchange (ETDEWEB)

    Iga, Keita, E-mail: iga@aori.u-tokyo.ac.jp [Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba 277-8564 (Japan)

    2017-12-15

    Axisymmetric flow in a cylindrical tank over a rotating bottom is investigated and its approximate solution with an analytic expression is obtained. The interior region, comprising the majority of the fluid, consists of two sub-regions. It is easily shown that a rigid-body rotational flow with the same rotation rate as that of the bottom is formed in the inner interior and that a potential flow with constant angular momentum occurs in the outer interior sub-region. However, the radius that divides these two sub-regions has not been determined. To determine this radius, the structures of the boundary layers are investigated in detail. These boundary layers surround the interior regions, and include the boundaries between the interior region and the side wall of the tank, between the interior and the bottom, and between the inner and outer interior sub-regions. By connecting the flows in the boundary layers, the vertical circulation as a whole is established, and consequently the radius dividing the two interior sub-regions is successfully determined as a function of the aspect ratio of the water layer region. This axisymmetric flow will be utilized as the basic state for investigating theoretically various non-axisymmetric phenomena observed in laboratory experiments. (paper)

  12. Emergence of a Stern Layer from the Incorporation of Hydration Interactions into the Gouy-Chapman Model of the Electrical Double Layer.

    Science.gov (United States)

    Brown, Matthew A; Bossa, Guilherme Volpe; May, Sylvio

    2015-10-27

    In one of the most commonly used phenomenological descriptions of the electrical double layer, a charged solid surface and a diffuse region of mobile ions are separated from each other by a thin charge-depleted Stern layer. The Stern layer acts as a capacitor that improves the classical Gouy-Chapman model by increasing the magnitude of the surface potential and limiting the maximal counterion concentration. We show that very similar Stern-like properties of the diffuse double layer emerge naturally from adding a nonelectrostatic hydration repulsion to the electrostatic Coulomb potential. The interplay of electrostatic attraction and hydration repulsion of the counterions and the surface leads to the formation of a diffuse counterion layer that remains well separated from the surface. In addition, hydration repulsions between the ions limit and control the maximal ion concentration and widen the width of the diffuse double layer. Our mean-field model, which we express in terms of electrostatic and hydration potentials, is physically consistent and conceptually similar to the classical Gouy-Chapman model. It allows the incorporation of ion specificity, accounts for hydration properties of charged surfaces, and predicts Stern layer properties, which we analyze in terms of the effective size of the hydrated counterions.

  13. Vertical distribution, composition and migratory patterns of acoustic scattering layers in the Canary Islands

    KAUST Repository

    Ariza, A.

    2016-01-21

    Diel vertical migration (DVM) facilitates biogeochemical exchanges between shallow waters and the deep ocean. An effective way of monitoring the migrant biota is by acoustic observations although the interpretation of the scattering layers poses challenges. Here we combine results from acoustic observations at 18 and 38 kHz with limited net sampling in order to unveil the origin of acoustic phenomena around the Canary Islands, subtropical northeast Atlantic Ocean. Trawling data revealed a high diversity of fishes, decapods and cephalopods (152 species), although few dominant species likely were responsible for most of the sound scattering in the region. We identified four different acoustic scattering layers in the mesopelagic realm: (1) at 400–500 m depth, a swimbladder resonance phenomenon at 18 kHz produced by gas-bearing migrant fish such as Vinciguerria spp. and Lobianchia dofleini, (2) at 500–600 m depth, a dense 38 kHz layer resulting primarily from the gas-bearing and non-migrant fish Cyclothone braueri, and to a lesser extent, from fluid-like migrant fauna also inhabiting these depths, (3) between 600 and 800 m depth, a weak signal at both 18 and 38 kHz ascribed either to migrant fish or decapods, and (4) below 800 m depth, a weak non-migrant layer at 18 kHz which was not sampled. All the dielly migrating layers reached the epipelagic zone at night, with the shorter-range migrations moving at 4.6 ± 2.6 cm s − 1 and the long-range ones at 11.5 ± 3.8 cm s − 1. This work reduces uncertainties interpreting standard frequencies in mesopelagic studies, while enhances the potential of acoustics for future research and monitoring of the deep pelagic fauna in the Canary Islands.

  14. Temperature and species measurement in a quenching boundary layer on a flat-flame burner

    Energy Technology Data Exchange (ETDEWEB)

    Fuyuto, Takayuki; Fujikawa, Taketoshi; Akihama, Kazuhiro [Toyota Central Research and Development Labs., Inc., Nagakute, Aichi (Japan); Kronemayer, Helmut [University of Duisburg-Essen, IVG, Institute for Combustion and Gasdynamics, Duisburg (Germany); BASF SE, Ludwigshafen (Germany); Lewerich, Burkhard; Dreier, Thomas; Schulz, Christof [University of Duisburg-Essen, IVG, Institute for Combustion and Gasdynamics, Duisburg (Germany); Bruebach, Jan [Technical University Darmstadt, EKT, Institute for Energy and Powerplant Technology, Darmstadt (Germany)

    2010-10-15

    A detailed understanding of transport phenomena and reactions in near-wall boundary layers of combustion chambers is essential for further reducing pollutant emissions and improving thermal efficiencies of internal combustion engines. In a model experiment, the potential of laser-induced fluorescence (LIF) was investigated for measurements inside the boundary layer connected to flame-wall interaction at atmospheric pressure. Temperature and species distributions were measured in the quenching boundary layer formed close to a cooled metal surface located parallel to the flow of a premixed methane/air flat flame. Multi-line NO-LIF thermometry provided gas-phase temperature distributions. In addition, flame species OH, CH{sub 2}O and CO were monitored by single-photon (OH, CH{sub 2}O) and two-photon (CO) excitation LIF, respectively. The temperature dependence of the OH-LIF signal intensities was corrected for using the measured gas-phase temperature distributions. The spatial line-pair resolution of the imaging system was 22 {mu}m determined by imaging microscopic line pairs printed on a resolution target. The experimental results show the expected flame quenching behavior in the boundary layer and they reveal the potential and limitations of the applied diagnostics techniques. Limitations in spatial resolution are attributed to refraction of fluorescence radiation propagating through steep temperature gradients in the boundary layer. For the present experimental arrangements, the applied diagnostics techniques are applicable as close to the wall as 200 {mu}m with measurement precision then exceeding the 15-25% limit for species detection, with estimates of double this value for the case of H{sub 2}CO due to the unknown effect of the Boltzmann fraction corrections not included in the data evaluation process. Temperature measurements are believed to be accurate within 50 K in the near-wall zone, which amounts to roughly 10% at the lower temperatures encountered in

  15. Vertical distribution, composition and migratory patterns of acoustic scattering layers in the Canary Islands

    KAUST Repository

    Ariza, A.; Landeira, J.M.; Escá nez, A.; Wienerroither, R.; Aguilar de Soto, N.; Rø stad, Anders; Kaartvedt, S.; Herná ndez-Leó n, S.

    2016-01-01

    Diel vertical migration (DVM) facilitates biogeochemical exchanges between shallow waters and the deep ocean. An effective way of monitoring the migrant biota is by acoustic observations although the interpretation of the scattering layers poses challenges. Here we combine results from acoustic observations at 18 and 38 kHz with limited net sampling in order to unveil the origin of acoustic phenomena around the Canary Islands, subtropical northeast Atlantic Ocean. Trawling data revealed a high diversity of fishes, decapods and cephalopods (152 species), although few dominant species likely were responsible for most of the sound scattering in the region. We identified four different acoustic scattering layers in the mesopelagic realm: (1) at 400–500 m depth, a swimbladder resonance phenomenon at 18 kHz produced by gas-bearing migrant fish such as Vinciguerria spp. and Lobianchia dofleini, (2) at 500–600 m depth, a dense 38 kHz layer resulting primarily from the gas-bearing and non-migrant fish Cyclothone braueri, and to a lesser extent, from fluid-like migrant fauna also inhabiting these depths, (3) between 600 and 800 m depth, a weak signal at both 18 and 38 kHz ascribed either to migrant fish or decapods, and (4) below 800 m depth, a weak non-migrant layer at 18 kHz which was not sampled. All the dielly migrating layers reached the epipelagic zone at night, with the shorter-range migrations moving at 4.6 ± 2.6 cm s − 1 and the long-range ones at 11.5 ± 3.8 cm s − 1. This work reduces uncertainties interpreting standard frequencies in mesopelagic studies, while enhances the potential of acoustics for future research and monitoring of the deep pelagic fauna in the Canary Islands.

  16. Stable evaluation of Green's functions in cylindrically stratified regions with uniaxial anisotropic layers

    Science.gov (United States)

    Moon, H.; Donderici, B.; Teixeira, F. L.

    2016-11-01

    We present a robust algorithm for the computation of electromagnetic fields radiated by point sources (Hertzian dipoles) in cylindrically stratified media where each layer may exhibit material properties (permittivity, permeability, and conductivity) with uniaxial anisotropy. Analytical expressions are obtained based on the spectral representation of the tensor Green's function based on cylindrical Bessel and Hankel eigenfunctions, and extended for layered uniaxial media. Due to the poor scaling of these eigenfunctions for extreme arguments and/or orders, direct numerical evaluation of such expressions can produce numerical instability, i.e., underflow, overflow, and/or round-off errors under finite precision arithmetic. To circumvent these problems, we develop a numerically stable formulation through suitable rescaling of various expressions involved in the computational chain, to yield a robust algorithm for all parameter ranges. Numerical results are presented to illustrate the robustness of the formulation including cases of practical interest.

  17. Intercalation compounds involving inorganic layered structures

    Directory of Open Access Journals (Sweden)

    CONSTANTINO VERA R. L.

    2000-01-01

    Full Text Available Two-dimensional inorganic networks can shown intracrystalline reactivity, i.e., simple ions, large species as Keggin ions, organic species, coordination compounds or organometallics can be incorporated in the interlayer region. The host-guest interaction usually causes changes in their chemical, catalytic, electronic and optical properties. The isolation of materials with interesting properties and making use of soft chemistry routes have given rise the possibility of industrial and technological applications of these compounds. We have been using several synthetic approaches to intercalate porphyrins and phthalocyanines into inorganic materials: smectite clays, layered double hydroxides and layered niobates. The isolated materials have been characterized by elemental and thermal analysis, X-ray diffraction, surface area measurements, scanning electronic microscopy, electronic and resonance Raman spectroscopies and EPR. The degree of layer stacking and the charge density of the matrices as well their acid-base nature were considered in our studies on the interaction between the macrocycles and inorganic hosts.

  18. Cobalt Coordination and Clustering in α-Co(OH)2 Revealed by Synchrotron X-ray Total Scattering

    International Nuclear Information System (INIS)

    Neilson, James R.; Kurzman, Joshua A.; Seshadri, Ram; Morse, Daniel E.

    2010-01-01

    Structures of layered metal hydroxides are not well described by traditional crystallography. Total scattering from a synthesis-controlled subset of these materials, as described here, reveals that different cobalt coordination polyhedra cluster within each layer on short length scales, offering new insights and approaches for understanding the properties of these and related layered materials. Structures related to that of brucite (Mg(OH) 2 ) are ubiquitous in the mineral world and offer a variety of useful functions ranging from catalysis and ion-exchange to sequestration and energy transduction, including applications in batteries. However, it has been difficult to resolve the atomic structure of these layered compounds because interlayer disorder disrupts the long-range periodicity necessary for diffraction-based structure determination. For this reason, traditional unit-cell-based descriptions have remained inaccurate. Here we apply, for the first time to such layered hydroxides, synchrotron X-ray total scattering methods - analyzing both the Bragg and diffuse components - to resolve the intralayer structure of three different α-cobalt hydroxides, revealing the nature and distribution of metal site coordination. The different compounds with incorporated chloride ions have been prepared with kinetic control of hydrolysis to yield different ratios of octahedrally and tetrahedrally coordinated cobalt ions within the layers, as confirmed by total scattering. Real-space analyses indicate local clustering of polyhedra within the layers, manifested in the weighted average of different ordered phases with fixed fractions of tetrahedrally coordinated cobalt sites. These results, hidden from an averaged unit-cell description, reveal new structural characteristics that are essential to understanding the origin of fundamental material properties such as color, anion exchange capacity, and magnetic behavior. Our results also provide further insights into the detailed

  19. Cobalt coordination and clustering in alpha-Co(OH)(2) revealed by synchrotron X-ray total scattering.

    Science.gov (United States)

    Neilson, James R; Kurzman, Joshua A; Seshadri, Ram; Morse, Daniel E

    2010-09-03

    Structures of layered metal hydroxides are not well described by traditional crystallography. Total scattering from a synthesis-controlled subset of these materials, as described here, reveals that different cobalt coordination polyhedra cluster within each layer on short length scales, offering new insights and approaches for understanding the properties of these and related layered materials. Structures related to that of brucite [Mg(OH)(2)] are ubiquitous in the mineral world and offer a variety of useful functions ranging from catalysis and ion-exchange to sequestration and energy transduction, including applications in batteries. However, it has been difficult to resolve the atomic structure of these layered compounds because interlayer disorder disrupts the long-range periodicity necessary for diffraction-based structure determination. For this reason, traditional unit-cell-based descriptions have remained inaccurate. Here we apply, for the first time to such layered hydroxides, synchrotron X-ray total scattering methods-analyzing both the Bragg and diffuse components-to resolve the intralayer structure of three different alpha-cobalt hydroxides, revealing the nature and distribution of metal site coordination. The different compounds with incorporated chloride ions have been prepared with kinetic control of hydrolysis to yield different ratios of octahedrally and tetrahedrally coordinated cobalt ions within the layers, as confirmed by total scattering. Real-space analyses indicate local clustering of polyhedra within the layers, manifested in the weighted average of different ordered phases with fixed fractions of tetrahedrally coordinated cobalt sites. These results, hidden from an averaged unit-cell description, reveal new structural characteristics that are essential to understanding the origin of fundamental material properties such as color, anion exchange capacity, and magnetic behavior. Our results also provide further insights into the detailed

  20. Layered double hydroxides as fillers in poly(l-lactide nanocomposites, obtained by in situ bulk polymerization

    Directory of Open Access Journals (Sweden)

    Telma Nogueira

    Full Text Available Abstract In this study in situ bulk polymerization of L-lactide filled with layered double hydroxides (LDH was investigated. Four different LDHs intercalated with two different organic anions (salicylate and sebacate were synthesized and characterized. After characterization, these synthetic layered compounds were used as fillers in poly(L-lactide (PLLA nanocomposites with two different fillers’s loadings (1 wt% and 2 wt%. PLLA and PLLA nanocomposites were evaluated by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, ultraviolet and visible spectroscopy, thermogravimetric analysis (TGA, dynamical mechanical analysis (DMA, flexural testing and differential scanning calorimetry (DSC. The results demonstrated that, compared to PLLA, the nanocomposite containing 1 wt% of Zn/Al salicylate transmitted less UVA and UVB light, while keeping a similar transparency in the visible region. Thermogravimetric analysis revealed that the nanocomposite with 1 wt% of Zn/Al salicylate exhibited the highest thermal stability. In general the flexural and dynamical mechanical properties were reduced in compassion to neat PLLA. DSC results, demonstrated that, compared to PLLA, all the nanocomposites exhibited lower glass transition temperature and melting temperature values.

  1. Silicon-ion-implanted PMMA with nanostructured ultrathin layers for plastic electronics

    Science.gov (United States)

    Hadjichristov, G. B.; Ivanov, Tz E.; Marinov, Y. G.

    2014-12-01

    Being of interest for plastic electronics, ion-beam produced nanostructure, namely silicon ion (Si+) implanted polymethyl-methacrylate (PMMA) with ultrathin nanostructured dielectric (NSD) top layer and nanocomposite (NC) buried layer, is examined by electric measurements. In the proposed field-effect organic nanomaterial structure produced within the PMMA network by ion implantation with low energy (50 keV) Si+ at the fluence of 3.2 × 1016 cm-2 the gate NSD is ion-nanotracks-modified low-conductive surface layer, and the channel NC consists of carbon nanoclusters. In the studied ion-modified PMMA field-effect configuration, the gate NSD and the buried NC are formed as planar layers both with a thickness of about 80 nm. The NC channel of nano-clustered amorphous carbon (that is an organic semiconductor) provides a huge increase in the electrical conduction of the material in the subsurface region, but also modulates the electric field distribution in the drift region. The field effect via the gate NSD is analyzed. The most important performance parameters, such as the charge carrier field-effect mobility and amplification of this particular type of PMMA- based transconductance device with NC n-type channel and gate NSD top layer, are determined.

  2. Macular Choroidal Small-Vessel Layer, Sattler's Layer and Haller's Layer Thicknesses: The Beijing Eye Study.

    Science.gov (United States)

    Zhao, Jing; Wang, Ya Xing; Zhang, Qi; Wei, Wen Bin; Xu, Liang; Jonas, Jost B

    2018-03-13

    To study macular choroidal layer thickness, 3187 study participants from the population-based Beijing Eye Study underwent spectral-domain optical coherence tomography with enhanced depth imaging for thickness measurements of the macular small-vessel layer, including the choriocapillaris, medium-sized choroidal vessel layer (Sattler's layer) and large choroidal vessel layer (Haller's layer). In multivariate analysis, greater thickness of all three choroidal layers was associated (all P  0.05) associated with the prevalence of open-angle glaucoma or diabetic retinopathy. There was a tendency (0.07 > P > 0.02) toward thinner choroidal layers in chronic angle-closure glaucoma. The ratio of small-vessel layer thickness to total choroidal thickness increased (P layer and Haller's layer thickness to total choroidal thickness decreased. A higher ratio of small-vessel layer thickness to total choroidal thickness was significantly associated with a lower prevalence of AMD (early type, intermediate type, late geographic type). Axial elongation-associated and aging-associated choroidal thinning affected Haller's and Sattler's layers more markedly than the small-vessel layer. Non-exudative and exudative AMD, except for geographic atrophy, was associated with slightly increased choroidal thickness.

  3. Surfactant-induced layered growth in homoepitaxy of Fe on Fe(100)-c(2 x 2)O reconstruction surface

    International Nuclear Information System (INIS)

    Kamiko, Masao; Mizuno, Hiroyuki; Chihaya, Hiroaki; Xu, Junhua; Kojima, Isao; Yamamoto, Ryoichi

    2007-01-01

    In this study, the effects of several surfactants (Pb, Bi, and Ag) on the homoepitaxial growth of Fe(100) were studied and compared. The reflection high-energy electron diffraction measurements clearly reveal that these surfactants enhance the layer-by-layer growth of Fe on an Fe(100)-c(2 x 2)O reconstruction surface. The dependence of growth on the surfactant layer thickness suggests that there exists a suitable amount of surfactant layer that induces a smoother layer-by-layer growth. Comparisons between the atomic force microscopy images reveal that the root-mean-square surface roughness of Fe films mediated by Pb and Bi surfactants are considerably smaller than those of the films mediated by Ag surfactant. The Auger electron spectra show that Pb and Bi segregate at the top of the surface. It has been concluded that Pb and Bi are effective surfactants for enhancing layer-by-layer growth in Fe homoepitaxy. Ag has the same effect, but it is less efficient due to the weak surface segregation of Ag

  4. Administrative Area Boundaries 2 (State Boundaries), Region 9, 2010, NAVTEQ

    Data.gov (United States)

    U.S. Environmental Protection Agency — NAVTEQ Administrative Area Boundaries 2 (State Boundaries) for Region 9. There are five Administrative Area Boundaries layers (1, 2, 3, 4, 5). These layers contain...

  5. Administrative Area Boundaries 4 (City Boundaries), Region 9, 2010, NAVTEQ

    Data.gov (United States)

    U.S. Environmental Protection Agency — NAVTEQ Administrative Area Boundaries 4 (City Boundaries) for Region 9. There are five Administrative Area Boundaries layers (1, 2, 3, 4, 5). These layers contain...

  6. An investigation of the effects of the propeller slipstream of a laminar wing boundary layer

    Science.gov (United States)

    Howard, R. M.; Miley, S. J.; Holmes, B. J.

    1985-01-01

    A research program is in progress to study the effects of the propeller slipstream on natural laminar flow. Flight and wind tunnel measurements of the wing boundary layer have been made using hot-film velocity sensor probes. The results show the boundary layer, at any given point, to alternate between laminar and turbulent states. This cyclic behavior is due to periodic external flow turbulence originating from the viscous wake of the propeller blades. Analytic studies show the cyclic laminar/turbulent boundary layer to result in a significantly lower wing section drag than a fully turbulent boundary layer. The application of natural laminar flow design philosophy yields drag reduction benefits in the slipstream affected regions of the airframe, as well as the unaffected regions.

  7. Stability of hypersonic boundary-layer flows with chemistry

    Science.gov (United States)

    Reed, Helen L.; Stuckert, Gregory K.; Haynes, Timothy S.

    1993-01-01

    The effects of nonequilibrium chemistry and three dimensionality on the stability characteristics of hypersonic flows are discussed. In two-dimensional (2-D) and axisymmetric flows, the inclusion of chemistry causes a shift of the second mode of Mack to lower frequencies. This is found to be due to the increase in size of the region of relative supersonic flow because of the lower speeds of sound in the relatively cooler boundary layers. Although this shift in frequency is present in both the equilibrium and nonequilibrium air results, the equilibrium approximation predicts modes which are not observed in the nonequilibrium calculations (for the flight conditions considered). These modes are superpositions of incoming and outgoing unstable disturbances which travel supersonically relative to the boundary-layer edge velocity. Such solutions are possible because of the finite shock stand-off distance. Their corresponding wall-normal profiles exhibit an oscillatory behavior in the inviscid region between the boundary-layer edge and the bow shock. For the examination of three-dimensional (3-D) effects, a rotating cone is used as a model of a swept wing. An increase of stagnation temperature is found to be only slightly stabilizing. The correlation of transition location (N = 9) with parameters describing the crossflow profile is discussed. Transition location does not correlate with the traditional crossflow Reynolds number. A new parameter that appears to correlate for boundary-layer flow was found. A verification with experiments on a yawed cone is provided.

  8. Energetic magnetospheric protons in the plasma depletion layer

    International Nuclear Information System (INIS)

    Fuselier, S.A.

    1992-01-01

    Interplanetary magnetic field draping against the Earth's dayside subsolar magnetopause creates a region of reduced plasma density and increased magnetic field called the plasma depletion layer. In this region, leakage of energetic ions from the Earth's magnetosphere onto magnetic field lines in the plasma depletion layer can be studied without interference from ions accelerated at the Earth's quasi-parallel bow shock. Active Magnetospheric Particle Tracer Experiment/Charge Composition Explorer (AMPTE/CCE) observations for 13 plasma depletion layer events are used to determine the characteristics of energetic protons between a few keV/e and ∼100keV/e leaked from the magnetosphere. Results indicate that the leaked proton distributions resemble those in the magnetosphere except that they have lower densities and temperatures and much higher velocities parallel (or antiparallel) and perpendicular to the magnetic field. Compared to the low-energy magnetosheath proton distributions present in the depletion layer, the leaked energetic proton distributions typically have substantially higher flow velocities along the magnetic field indicate that the leaked energetic proton distributions to contribute to the energetic proton population seen upstream and downstream from the quasi-parallel bow shock. However, their contribution is small compared to the contribution from acceleration of protons at the bow shock because the leaked proton densities are on the order of 10 times smaller than the energetic proton densities typically observed in the vicinity of the quasi-parallel bow shock

  9. Cardiac Myocyte Diversity and a Fibroblast Network in the Junctional Region of the Zebrafish Heart Revealed by Transmission and Serial Block-Face Scanning Electron Microscopy

    KAUST Repository

    Lafontant, Pascal J.

    2013-08-23

    The zebrafish has emerged as an important model of heart development and regeneration. While the structural characteristics of the developing and adult zebrafish ventricle have been previously studied, little attention has been paid to the nature of the interface between the compact and spongy myocardium. Here we describe how these two distinct layers are structurally and functionally integrated. We demonstrate by transmission electron microscopy that this interface is complex and composed primarily of a junctional region occupied by collagen, as well as a population of fibroblasts that form a highly complex network. We also describe a continuum of uniquely flattened transitional cardiac myocytes that form a circumferential plate upon which the radially-oriented luminal trabeculae are anchored. In addition, we have uncovered within the transitional ring a subpopulation of markedly electron dense cardiac myocytes. At discrete intervals the transitional cardiac myocytes form contact bridges across the junctional space that are stabilized through localized desmosomes and fascia adherentes junctions with adjacent compact cardiac myocytes. Finally using serial block-face scanning electron microscopy, segmentation and volume reconstruction, we confirm the three-dimensional nature of the junctional region as well as the presence of the sheet-like fibroblast network. These ultrastructural studies demonstrate the previously unrecognized complexity with which the compact and spongy layers are structurally integrated, and provide a new basis for understanding development and regeneration in the zebrafish heart. © 2013 Lafontant et al.

  10. Preparation of CuGaSe2 absorber layers for thin film solar cells by annealing of efficiently electrodeposited Cu-Ga precursor layers from ionic liquids

    International Nuclear Information System (INIS)

    Steichen, M.; Larsen, J.; Guetay, L.; Siebentritt, S.; Dale, P.J.

    2011-01-01

    CuGaSe 2 absorber layers were prepared on molybdenum substrates by electrochemical codeposition of copper and gallium and subsequential annealing in selenium vapour. The electrodeposition was made from a deep eutectic based ionic liquid consisting of choline chloride/urea (Reline) with a plating efficiency of over 85%. The precursor film composition is controlled by the ratio of the copper to gallium fluxes under hydrodynamic conditions and by the applied deposition potential. X-ray diffraction reveals CuGa 2 alloying during the electrodeposition and CuGaSe 2 formation after annealing. Photoluminescence (PL) and photocurrent spectroscopy revealed the good opto-electronic properties of the CuGaSe 2 absorber films. The absorber layers have been converted to full devices with the best device achieving 4.0 % solar conversion efficiency.

  11. InN layers grown by the HVPE

    International Nuclear Information System (INIS)

    Syrkin, A.L.; Ivantsov, V.; Usikov, A.; Dmitriev, V.A.; Chambard, G.; Ruterana, P.; Davydov, A.V.; Sundaresan, S.G.; Lutsenko, E.; Mudryi, A.V.; Readinger, E.D.; Chern-Metcalfe, G.D.; Wraback, M.

    2008-01-01

    We report on the properties of high quality HVPE InN and on successful subsequent MBE growth of InN layers with improved characteristics on HVPE InN template substrates. InN layers were grown by HVPE on GaN/sapphire HVPE templates. The (00.2) XRD rocking curve of the best InN layer (RC) had the FWHM of about 375 arc sec, being the narrowest XRD RCs ever reported for HVPE InN. Transmission Electron Microscopy (TEM) revealed that at the GaN/InN interface, the threading dislocations that come from GaN were transmitted into the InN layer. We estimated the dislocation density in HVPE grown InN to be in the low 10 9 cm -2 range. Reflection high energy electron diffraction (RHEED) confirmed monocrystalline structure of the InN layers surface. Layers photoluminescence (PL) showed edge emission around 0.8 eV. Hall measured free electron concentration was in the range of 10 19 -10 20 cm -3 and electron mobility was ∝200 cm 2 /V s. MBE growth of InN was performed on the HVPE grown InN template substrate demonstrating the improvement of material quality in the case of homo-epitaxial growth of InN. Demonstration of the high quality HVPE InN materials opens a new way for InN substrate development. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Effect of layered manufacturing techniques, alloy powders, and layer thickness on metal-ceramic bond strength.

    Science.gov (United States)

    Ekren, Orhun; Ozkomur, Ahmet; Ucar, Yurdanur

    2018-03-01

    Direct metal laser sintering (DMLS) and direct metal laser melting (DMLM) have become popular for fabricating the metal frameworks of metal-ceramic restorations. How the type of layered manufacturing device, layer thickness, and alloy powder may affect the bond strength of ceramic to metal substructure is unclear. The purpose of this in vitro study was to evaluate the bond strength of dental porcelain to metal frameworks fabricated using different layered manufacturing techniques (DMLS and DMLM), Co-Cr alloy powders, and layer thicknesses and to evaluate whether a correlation exists between the bond strength and the number of ceramic remnants on the metal surface. A total of 75 bar-shaped metal specimens (n=15) were fabricated using either DMLS or DMLM. The powder alloys used were Keramit NP-S and EOS-Cobalt-Chrome SP-2 with layer thicknesses of 20 μm and 30 μm. After ceramic application, the metal-ceramic bond strength was evaluated with a 3-point-bend test. Three-way ANOVA followed by the Tukey honest significance difference test were used for statistical analysis (α=.05). De-bonding surface microstructure was observed with scanning electron microscopy. Energy dispersive spectroscopy analysis was conducted to evaluate the correlation between ceramic remnants on the metal surface and bond strength values. The mean bond strength value of DMLS was significantly higher than that of DMLM. While no statistically significant difference was found between layer thicknesses, alloy powders closely affected bond strength. Statistical comparisons revealed that the highest bond strength could be achieved with DMLS-Cobalt-Chrome SP2-20μm, and the lowest bond strength was observed in DMLS-Keramit NP-S-20μm (P≤.05). No correlation was found between porcelain remnants on the metal surface and bond strength values. The layered manufacturing device and the alloy powders evaluated in the current study closely affected the bond strength of dental porcelain to a metal framework

  13. High temperature study on the thermal properties of few-layer Mo0.5W0.5S2 and effects of capping layers

    Directory of Open Access Journals (Sweden)

    Hong Gu

    Full Text Available We investigated the thermal properties of few-layer Mo0.5W0.5S2 using a series of samples with different kinds of capping layers. Temperature-dependent Raman measurements were conducted in the range of 300–500 K, with power-dependent measurements also carried out. It indicated, for the few-layer Mo0.5W0.5S2, the temperature coefficients of the WS2-like E12g mode, MoS2-like E12g mode and A1g mode were −0.0155 cm−1/K, −0.0146 cm−1/K, and −0.0130 cm−1/K, respectively. And the thermal conductivity was estimated to be 44.8 W/mK. Moreover, the Mo0.5W0.5S2 samples coated with capping layers (ZrO2, HfO2 both showed a better thermal stability and a larger thermal conductivity than the one without. The results revealed that the capping layer should be an important factor in the thermal property. Keywords: Mo0.5W0.5S2, TMDs, Thermal properties, High temperature, Capping layers, Raman

  14. Effects of layer-multiplying and interface on the content of β-transcrystallization in PP

    International Nuclear Information System (INIS)

    Lei, Fan; Li, Jiang; Guo, Shaoyun

    2015-01-01

    The alternating multilayered polypropylene (PP layer)/β-nucleating agent filled-polypropylene (β-PP layer) were prepared through layer-multiplying extrusion combined with an assembly of layer-multiplying elements (LM Es). The content of β-crystal was firstly evaluated by differential scanning calorimetry (DSC), which indicated that the relative amount of the β-crystal increased from 38.67% to 81.22% with the increase of layer numbers from 2-layer to 128-layer. It was well consistent with the results of X-ray diffraction (XRD). The morphology observation of β-crystal by polarizing microscope (POM) revealed that the closely packed nuclei in the interface could induce numerous β-transcrystallization in pure PP layer due to the confinement effect. The non-isothermal crystallization kinetic analysis via Mozhishen’s methods manifested that the crystallization rate was greatly enhanced by the augment of the layered interface

  15. Hawaii Regional Sediment Management Needs Assessment

    Science.gov (United States)

    2014-07-01

    The revet- ment has a crest elevation of +12 ft, 1–4 ton armor stone (two layers thick), ERDC/CHL TR-14-4 8 revetment toe (three stones wide...with calcareous pocket beaches and fringing reef. The Mahaulepu sub-region contains lithified sand dunes ...extensive sand dune system.1 The Polihale, Majors Bay, Oomano, and Kikiaola Shallow Draft Harbor sub- regions comprise the West Kauai region (Figure 7

  16. Regional cerebral palmitate incorporation following transient bilateral carotid occlusion in awake gerbils

    Energy Technology Data Exchange (ETDEWEB)

    Tone, O.; Miller, J.C.; Bell, J.M.; Rapoport, S.I.

    1987-11-01

    (/sup 14/C)Palmitate was injected intravenously in awake gerbils at various times after 5 minutes of bilateral carotid artery occlusion or a sham operation. Regional rates of incorporation of plasma palmitate into the hippocampus and other regions of the anterior circulation were determined relative to the mean rate of incorporation into regions of the posterior circulation using quantitative autoradiography and a ratio method of analysis. One day after bilateral carotid occlusion, relative palmitate incorporation was elevated significantly by 16% in the CA4 pyramidal cell layer and by 20% in the dentate gyrus of the hippocampus compared with sham-operated gerbils. At 3 days, significant elevations of this magnitude were found in the CA3 and CA4 cell layers, whereas relative incorporation was reduced by 26% in the CA1 pyramidal cell layer. At 7 days, the only significant difference from control was a 15% elevated incorporation in the CA3 pyramidal cell layer. Histologic examination indicated substantial cell death in the CA1 pyramidal layer at 3 days, with extensive glial reaction and phagocytic invasion at 7 days. Our results suggest that the turnover of palmitate-containing lipids is reduced in the CA1 layer of the gerbil hippocampus but that lipid synthesis is stimulated in hippocampal regions (CA3, CA4, dentate gyrus) affected by but recovering from transient bilateral carotid occlusion.

  17. Regional cerebral palmitate incorporation following transient bilateral carotid occlusion in awake gerbils

    International Nuclear Information System (INIS)

    Tone, O.; Miller, J.C.; Bell, J.M.; Rapoport, S.I.

    1987-01-01

    [ 14 C]Palmitate was injected intravenously in awake gerbils at various times after 5 minutes of bilateral carotid artery occlusion or a sham operation. Regional rates of incorporation of plasma palmitate into the hippocampus and other regions of the anterior circulation were determined relative to the mean rate of incorporation into regions of the posterior circulation using quantitative autoradiography and a ratio method of analysis. One day after bilateral carotid occlusion, relative palmitate incorporation was elevated significantly by 16% in the CA4 pyramidal cell layer and by 20% in the dentate gyrus of the hippocampus compared with sham-operated gerbils. At 3 days, significant elevations of this magnitude were found in the CA3 and CA4 cell layers, whereas relative incorporation was reduced by 26% in the CA1 pyramidal cell layer. At 7 days, the only significant difference from control was a 15% elevated incorporation in the CA3 pyramidal cell layer. Histologic examination indicated substantial cell death in the CA1 pyramidal layer at 3 days, with extensive glial reaction and phagocytic invasion at 7 days. Our results suggest that the turnover of palmitate-containing lipids is reduced in the CA1 layer of the gerbil hippocampus but that lipid synthesis is stimulated in hippocampal regions (CA3, CA4, dentate gyrus) affected by but recovering from transient bilateral carotid occlusion

  18. Electrical resistivity tomography determines the spatial distribution of clay layer thickness and aquifer vulnerability, Kandal Province, Cambodia

    Science.gov (United States)

    Uhlemann, Sebastian; Kuras, Oliver; Richards, Laura A.; Naden, Emma; Polya, David A.

    2017-10-01

    Despite being rich in water resources, many areas of South East Asia face difficulties in securing clean water supply. This is particularly problematic in regions with a rapidly growing population. In this study, the spatial variability of the thickness of a clay layer, controlling surface - groundwater interactions that affect aquifer vulnerability, was investigated using electrical resistivity tomography (ERT). Data were acquired along two transects, showing significant differences in the imaged resistivities. Borehole samples were analyzed regarding particle density and composition, and linked to their resistivity. The obtained relationships were used to translate the field electrical resistivities into lithologies. Those revealed considerable variations in the thickness of the clay layer, ranging from 0 m up to 25 m. Geochemical data, highlighting zones of increased ingress of surface water into the groundwater, confirmed areas of discontinuities in the clay layer, which act as preferential flow paths. The results may guide urban planning of the Phnom Penh city expansion, in order to supply the growing population with safe water. The presented approach of using geophysics to estimate groundwater availability, accessibility, and vulnerability is not only applicable to Kandal Province, Cambodia, but also to many other areas of fast urbanization in South East Asia and beyond.

  19. Weak localization in few-layer black phosphorus

    International Nuclear Information System (INIS)

    Du, Yuchen; Neal, Adam T; Zhou, Hong; Ye, Peide D

    2016-01-01

    We have conducted a comprehensive investigation into the magneto-transport properties of few-layer black phosphorus in terms of phase coherence length, phase coherence time, and mobility via weak localization measurement and Hall-effect measurement. We present magnetoresistance data showing the weak localization effect in bare p-type few-layer black phosphorus and reveal its strong dependence on temperature and carrier concentration. The measured weak localization agrees well with the Hikami–Larkin–Nagaoka model and the extracted phase coherence length of 104 nm at 350 mK, decreasing as ∼T −0.513+−0.053 with increased temperature. Weak localization measurement allows us to qualitatively probe the temperature-dependent phase coherence time τ ϕ , which is in agreement with the theory of carrier interaction in the diffusive regime. We also observe the universal conductance fluctuation phenomenon in few-layer black phosphorus within moderate magnetic field and low temperature regime. (paper)

  20. On the Initiation of an Isolated Convective Storm Near the Central Urban Area of Beijing Metropolitan Region

    Science.gov (United States)

    LI, H.; Cui, X.; Zhang, D. L.

    2017-12-01

    An isolated heavy-rain-producing convective storm was unexpectedly initiated in the early afternoon of 9 August 2011 near the central urban area of Beijing metropolitan region (BMR), which occurred at some distance from BMR's northwestern mountains and two pre-existing mesoscale convective systems (MCSs) to the north and west, respectively. An observational analysis shows the presence of large-scale quasi-geostrophic conditions but a favorable regional environment for the convective initiation (CI) of storms, including conditional instability, a low-level southerly flow and high-θe (equivalent potential temperature) area. A nested-grid (4/1.333 km) cloud-resolving model simulation of the case is performed to examine the CI of the storm. Results reveal that the growth of the mixed boundary layer, enhanced by the urban heat island (UHI) effects, accounts for the formation of a thin layer of clouds at the boundary-layer top at the CI site. However, this storm may not take place without sustained low-level convergence of high-θe air between a southerly flow and a northerly flow ahead of a cold outflow boundary associated with the northern MCS. The latter is driven by the latent heating of the shallow layer of clouds during the earlier CI stage and then a cold mesohigh associated with the northern MCS. The results indicate the important roles of the urban effects, mountain morphology, and convectively generated pressure perturbations in determining the CI location and timing of isolated convective storms over the BMR during the summer months.

  1. The different influence of the residual layer on the development of the summer convective boundary layer in two deserts in northwest China

    Science.gov (United States)

    Lin, Zhao; Bo, Han; Shihua, Lv; Lijuan, Wen; Xianhong, Meng; Zhaoguo, Li

    2018-02-01

    The development of the atmospheric boundary layer is closely connected with the exchange of momentum, heat, and mass near the Earth's surface, especially for a convective boundary layer (CBL). Besides being modulated by the buoyancy flux near the Earth's surface, some studies point out that a neutrally stratified residual layer is also crucial for the appearance of a deep CBL. To verify the importance of the residual layer, the CBLs over two deserts in northwest China (Badan Jaran and Taklimakan) were investigated. The summer CBL mean depth over the Taklimakan Desert is shallower than that over the Badan Jaran Desert, even when the sensible heat flux of the former is stronger. Meanwhile, the climatological mean residual layer in the Badan Jaran Desert is much deeper and neutrally stratified in summer. Moreover, we found a significant and negative correlation between the lapse rate of the residual layer and the CBL depth over the Badan Jaran Desert. The different lapse rates of the residual layer in the two regions are partly connected with the advection heating from large-scale atmospheric circulation. The advection heating tends to reduce the temperature difference in the 700 to 500-hPa layer over the Badan Jaran Desert, and it increases the stability in the same atmospheric layer over the Taklimakan Desert. The advection due to climatological mean atmospheric circulation is more effective at modulating the lapse rate of the residual layer than from varied circulation. Also, the interannual variation of planetary boundary layer (PBL) height over two deserts was found to covary with the wave train.

  2. Imaging of few‐layer graphene flakes

    DEFF Research Database (Denmark)

    Eriksen, René Lynge; Albrektsen, Ole; Novikov, Sergey M.

    In this work, we successfully demonstrate how imaging ellipsometry can be applied to obtain high‐resolution thickness maps of few‐layer graphene (FLG) samples, with the results being thoroughly validated in a comparative study using several complementary techniques: Optical reflection microscopy...... (ORM), atomic force microscopy (AFM), and scanning confocal Raman microscopy. The thickness map, revealing distinct terraces separated by steps corresponding to mono‐ and bilayers of graphene, is extracted from a pixel‐to‐pixel fitting of ellipsometric spectra using optical constants derived by fitting...... slab model calculations to averaged spectra collected in large homogenous sample areas. An analysis of reflection spectra and contrast images acquired by ORM confirm the results by quantifying the number of graphene layers and retrieving the FLG optical constants using a simple Fresnel‐law‐based slab...

  3. Charge migration contribution to the sensitive layer of a silicon detector

    International Nuclear Information System (INIS)

    Croitoru, N.; Seidman, A.; Rancoita, P.G.

    1984-01-01

    The charge migration from the field-free region has been investigated, by comparing the expected peak position (which takes into account the depleted layer only) of the energy-loss of relativistic electrons with the measured one. The measurement sensitive layer was found to be systematically larger than the depleted one. This effect is accounted for the charge migration to diffusion

  4. A comparative study on the performance of hybrid solar cells containing ZnSTe QDs in hole transporting layer and photoactive layer

    Energy Technology Data Exchange (ETDEWEB)

    Najeeb, Mansoor Ani [Qatar University, Center for Advanced Materials (CAM) (Qatar); Abdullah, Shahino Mah; Aziz, Fakhra [University of Malaya, Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science (Malaysia); Ahmad, Zubair, E-mail: zubairtarar@qu.edu.qa; Shakoor, R. A. [Qatar University, Center for Advanced Materials (CAM) (Qatar); Mohamed, A. M. A. [Suez University, Department of Metallurgical and Materials Engineering, Faculty of Petroleum and Mining Engineering (Egypt); Khalil, Uzma [University of Peshawar, Department of Electronics, Jinnah College for Women (Pakistan); Swelm, Wageh; Al-Ghamdi, Ahmed A. [King Abdulaziz University, Department of Physics, Faculty of Science (Saudi Arabia); Sulaiman, Khaulah [University of Malaya, Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science (Malaysia)

    2016-12-15

    In this paper, ZnSTe quantum dots-based hybrid solar cells (HSC) with two different device architectures have been investigated. The improved performance of the poly(3-hexylthiophene) (P3HT) and [6,6]phenyl C{sub 71} butyric acid methyl ester (PC{sub 71}BM)-based bulk heterojunction (BHJ) solar cells by the incorporation of ZnSTe quantum dots (QDs) with an average size of 2.96 nm in PEDOT:PSS layer and active layer that have been demonstrated. Although the efficiency of both types of devices is almost the same, a close comparison reveals different reasons behind their improved performance. The device prepared with QDs in the HTL has shown reduced series resistance, increased shunt resistance, and improved mobility. On the other hand, QDs in the photoactive layer demonstrates increased photo-generation leading to improved efficiency.

  5. Coherent structures in wave boundary layers. Part 1. Oscillatory motion

    DEFF Research Database (Denmark)

    Carstensen, Stefan; Sumer, B. Mutlu; Fredsøe, Jørgen

    2010-01-01

    This work concerns oscillatory boundary layers over smooth beds. It comprises combined visual and quantitative techniques including bed shear stress measurements. The experiments were carried out in an oscillating water tunnel. The experiments reveal two significant coherent flow structures: (i......) Vortex tubes, essentially two-dimensional vortices close to the bed extending across the width of the boundary-layer flow, caused by an inflectional-point shear layer instability. The imprint of these vortices in the bed shear stress is a series of small, insignificant kinks and dips. (ii) Turbulent...... spots, isolated arrowhead-shaped areas close to the bed in an otherwise laminar boundary layer where the flow ‘bursts’ with violent oscillations. The emergence of the turbulent spots marks the onset of turbulence. Turbulent spots cause single or multiple violent spikes in the bed shear stress signal...

  6. The Plasmasphere Boundary Layer

    Directory of Open Access Journals (Sweden)

    D. L. Carpenter

    2004-12-01

    Full Text Available As an inner magnetospheric phenomenon the plasmapause region is of interest for a number of reasons, one being the occurrence there of geophysically important interactions between the plasmas of the hot plasma sheet and of the cool plasmasphere. There is a need for a conceptual framework within which to examine and discuss these interactions and their consequences, and we therefore suggest that the plasmapause region be called the Plasmasphere Boundary Layer, or PBL. Such a term has been slow to emerge because of the complexity and variability of the plasma populations that can exist near the plasmapause and because of the variety of criteria used to identify the plasmapause in experimental data. Furthermore, and quite importantly in our view, a substantial obstacle to the consideration of the plasmapause region as a boundary layer has been the longstanding tendency of textbooks on space physics to limit introductory material on the plasmapause phenomenon to zeroth order descriptions in terms of ideal MHD theory, thus implying that the plasmasphere is relatively well understood. A textbook may introduce the concept of shielding of the inner magnetosphere from perturbing convection electric fields, but attention is not usually paid to the variety of physical processes reported to occur in the PBL, such as heating, instabilities, and fast longitudinal flows, processes which must play roles in plasmasphere dynamics in concert with the flow regimes associated with the major dynamo sources of electric fields. We believe that through the use of the PBL concept in future textbook discussions of the plasmasphere and in scientific communications, much progress can be made on longstanding questions about the physics involved in the formation of the plasmapause and in the cycles of erosion and recovery of the plasmasphere.

    Key words. Magnetospheric physics (plasmasphere; plasma convection; MHD waves and instabilities

  7. The Plasmasphere Boundary Layer

    Directory of Open Access Journals (Sweden)

    D. L. Carpenter

    2004-12-01

    Full Text Available As an inner magnetospheric phenomenon the plasmapause region is of interest for a number of reasons, one being the occurrence there of geophysically important interactions between the plasmas of the hot plasma sheet and of the cool plasmasphere. There is a need for a conceptual framework within which to examine and discuss these interactions and their consequences, and we therefore suggest that the plasmapause region be called the Plasmasphere Boundary Layer, or PBL. Such a term has been slow to emerge because of the complexity and variability of the plasma populations that can exist near the plasmapause and because of the variety of criteria used to identify the plasmapause in experimental data. Furthermore, and quite importantly in our view, a substantial obstacle to the consideration of the plasmapause region as a boundary layer has been the longstanding tendency of textbooks on space physics to limit introductory material on the plasmapause phenomenon to zeroth order descriptions in terms of ideal MHD theory, thus implying that the plasmasphere is relatively well understood. A textbook may introduce the concept of shielding of the inner magnetosphere from perturbing convection electric fields, but attention is not usually paid to the variety of physical processes reported to occur in the PBL, such as heating, instabilities, and fast longitudinal flows, processes which must play roles in plasmasphere dynamics in concert with the flow regimes associated with the major dynamo sources of electric fields. We believe that through the use of the PBL concept in future textbook discussions of the plasmasphere and in scientific communications, much progress can be made on longstanding questions about the physics involved in the formation of the plasmapause and in the cycles of erosion and recovery of the plasmasphere. Key words. Magnetospheric physics (plasmasphere; plasma convection; MHD waves and instabilities

  8. Low frequency solitons and double layers in a magnetized plasma with two temperature electrons

    Energy Technology Data Exchange (ETDEWEB)

    Rufai, O. R. [Department of Physics, University of the Western Cape, Private Bag X17, Bellville 7535 (South Africa); Bharuthram, R. [Office of the Deputy Vice Chancellor (Academic), University of the Western Cape, Bellville (South Africa); Singh, S. V. [Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai-410218 (India); School of Chemistry and Physics, University of Kwa-Zulu Natal, Durban (South Africa); Lakhina, G. S. [Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai-410218 (India)

    2012-12-15

    Finite amplitude non-linear ion-acoustic solitary waves and double layers are studied in a magnetized plasma with cold ions fluid and two distinct groups of Boltzmann electrons, using the Sagdeev pseudo-potential technique. The conditions under which the solitary waves and double layers can exist are found both analytically and numerically. We have shown the existence of negative potential solitary waves and double layers for subsonic Mach numbers, whereas in the unmagnetized plasma they can only in the supersonic Mach number regime. For the plasma parameters in the auroral region, the electric field amplitude of the solitary structures comes out to be 49 mV/m which is in agreement of the Viking observations in this region.

  9. Low frequency solitons and double layers in a magnetized plasma with two temperature electrons

    International Nuclear Information System (INIS)

    Rufai, O. R.; Bharuthram, R.; Singh, S. V.; Lakhina, G. S.

    2012-01-01

    Finite amplitude non-linear ion-acoustic solitary waves and double layers are studied in a magnetized plasma with cold ions fluid and two distinct groups of Boltzmann electrons, using the Sagdeev pseudo-potential technique. The conditions under which the solitary waves and double layers can exist are found both analytically and numerically. We have shown the existence of negative potential solitary waves and double layers for subsonic Mach numbers, whereas in the unmagnetized plasma they can only in the supersonic Mach number regime. For the plasma parameters in the auroral region, the electric field amplitude of the solitary structures comes out to be 49 mV/m which is in agreement of the Viking observations in this region.

  10. Inter-layer and intra-layer heat transfer in bilayer/monolayer graphene van der Waals heterostructure: Is there a Kapitza resistance analogous?

    Science.gov (United States)

    Rajabpour, Ali; Fan, Zheyong; Vaez Allaei, S. Mehdi

    2018-06-01

    Van der Waals heterostructures have exhibited interesting physical properties. In this paper, heat transfer in hybrid coplanar bilayer/monolayer (BL-ML) graphene, as a model layered van der Waals heterostructure, was studied using non-equilibrium molecular dynamics (MD) simulations. The temperature profile and inter- and intra-layer heat fluxes of the BL-ML graphene indicated that, there is no fully developed thermal equilibrium between layers and the drop in the average temperature profile at the step-like BL-ML interface is not attributable to the effect of Kapitza resistance. By increasing the length of the system up to 1 μm in the studied MD simulations, the thermally non-equilibrium region was reduced to a small area near the step-like interface. All MD results were compared to a continuum model and a good match was observed between the two approaches. Our results provide a useful understanding of heat transfer in nano- and micro-scale layered materials and van der Waals heterostructures.

  11. Spatial distribution and vertical profile of polybrominated diphenyl ethers, tetrabromobisphenol A, and decabromodiphenylethane in river sediment from an industrialized region of South China

    International Nuclear Information System (INIS)

    Zhang Xiulan; Luo Xiaojun; Chen Shejun; Wu Jiangping; Mai Bixian

    2009-01-01

    Polybrominated diphenyl ethers (PBDEs), tetrabromobisphenol A (TBBPA), and decabromodiphenylethane (DBDPE) were detected in fifteen surface sediments and two sediment cores collected from a river in one heavily industrialized region of South China. TBBPA and DBDPE were detected with concentrations ranging from 3.8 to 230 ng/g dw and from 23 to 430 ng/g dw, respectively. Σtri-hepta-BDEs and Σnona-deca-BDEs ranged from 0.7 to 7.6 ng/g dw and from 30 to 5700 ng/g dw, respectively. Σtri-hepta-BDEs showed an increasing trend whereas for Σnona-deca-BDE two sediment cores revealed a decreasing trend in more recent sediment layers which may attributed to the introduction of DBDPE. The rapid increasing trend for TBBPA and DBDPE in recent sediment layers well reflected the rising demand of these two compounds in study area. - Ubiquitous and historical contamination by PBDE, TBBPA, and DBDPE in river sediments from an industrialized region of South China

  12. Spatial distribution and vertical profile of polybrominated diphenyl ethers, tetrabromobisphenol A, and decabromodiphenylethane in river sediment from an industrialized region of South China

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xiulan [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Graduate School of the Chinese Academy of Science, Beijing 100039 (China); Luo Xiaojun, E-mail: luoxiaoj@gig.ac.c [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Chen Shejun [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Wu Jiangping [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Graduate School of the Chinese Academy of Science, Beijing 100039 (China); Mai Bixian [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China)

    2009-06-15

    Polybrominated diphenyl ethers (PBDEs), tetrabromobisphenol A (TBBPA), and decabromodiphenylethane (DBDPE) were detected in fifteen surface sediments and two sediment cores collected from a river in one heavily industrialized region of South China. TBBPA and DBDPE were detected with concentrations ranging from 3.8 to 230 ng/g dw and from 23 to 430 ng/g dw, respectively. SIGMAtri-hepta-BDEs and SIGMAnona-deca-BDEs ranged from 0.7 to 7.6 ng/g dw and from 30 to 5700 ng/g dw, respectively. SIGMAtri-hepta-BDEs showed an increasing trend whereas for SIGMAnona-deca-BDE two sediment cores revealed a decreasing trend in more recent sediment layers which may attributed to the introduction of DBDPE. The rapid increasing trend for TBBPA and DBDPE in recent sediment layers well reflected the rising demand of these two compounds in study area. - Ubiquitous and historical contamination by PBDE, TBBPA, and DBDPE in river sediments from an industrialized region of South China

  13. Textured strontium titanate layers on platinum by atomic layer deposition

    International Nuclear Information System (INIS)

    Blomberg, T.; Anttila, J.; Haukka, S.; Tuominen, M.; Lukosius, M.; Wenger, Ch.; Saukkonen, T.

    2012-01-01

    Formation of textured strontium titanate (STO) layers with large lateral grain size (0.2–1 μm) and low X-ray reflectivity roughness (∼ 1.36 nm) on Pt electrodes by industry proven atomic layer deposition (ALD) method is demonstrated. Sr(t-Bu 3 Cp) 2 , Ti(OMe) 4 and O 3 precursors at 250 °C were used to deposit Sr rich STO on Pt/Ti/SiO 2 /Si ∅200 mm substrates. After crystallization post deposition annealing at 600 °C in air, most of the STO grains showed a preferential orientation of the {001} plane parallel to the substrate surface, although other orientations were also present. Cross sectional and plan view transmission electron microscopy and electron diffraction analysis revealed more than an order of magnitude larger lateral grain sizes for the STO compared to the underlying multicrystalline {111} oriented platinum electrode. The combination of platinum bottom electrodes with ALD STO(O 3 ) shows a promising path towards the formation of single oriented STO film. - Highlights: ► Amorphous strontium titanate (STO) on platinum formed a textured film after annealing. ► Single crystal domains in 60 nm STO film were 0.2–1 μm wide. ► Most STO grains were {001} oriented.

  14. Radio tomographic imaging of sporadic-E layers during SEEK-2

    Directory of Open Access Journals (Sweden)

    P. A. Bernhardt

    2005-10-01

    Full Text Available During the SEEK-2 Rocket Campaign in August 2002, a Dual Band Beacon (DBB transmitting to Ground Receivers provided unique data on E-Region electron densities. Information from two rocket beacons and four ground receivers yielded multiple samples of E-region horizontal and vertical variations. The radio beacon measurements were made at four sites (Uchinoura, Tarumizu, Tanegashima, Takazaki in Japan for two rockets (S310-31 and S310-32 launched by the Institute of Space and Aeronautical Science (ISAS. Analysis was completed for four sets of beacon data to provide electron density images of sporadic-E layers. Signals from the two-frequency beacons on the SEEK-2 rockets were processed to yield total electron content (TEC data that was converted into electron density measurements. Wide variations in layer structures were detected. These included horizontal sporadic-E variations, vertical profiles of double, single, and weak layers. The radio beacon measurements were shown to be in agreement with the in-situ SEEK-2 sensors. The first tomographic image of a sporadic-E layer was produced from the data. The rocket beacon technique was shown to be an excellent tool to study sporadic-E layers because absolute TEC accuracy of 0.01 TEC Units can be easily obtained and, with proper receiver placement, electron density images can be produced using computerized ionospheric tomography with better than 1km horizontal and vertical resolution. Keywords. Ionospheric irregularities – Instruments and techniques – Mid-latitude ionosphere

  15. Grand Canonical Investigation of the Quasi Liquid Layer of Ice: Is It Liquid?

    Science.gov (United States)

    Pickering, Ignacio; Paleico, Martin; Sirkin, Yamila A Perez; Scherlis, Damian A; Factorovich, Matías H

    2018-05-10

    In this study, the solid-vapor equilibrium and the quasi liquid layer (QLL) of ice Ih exposing the basal and primary prismatic faces were explored by means of grand canonical molecular dynamics simulations with the monatomic mW potential. For this model, the solid-vapor equilibrium was found to follow the Clausius-Clapeyron relation in the range examined, from 250 to 270 K, with a Δ H sub of 50 kJ/mol in excellent agreement with the experimental value. The phase diagram of the mW model was constructed for the low pressure region around the triple point. The analysis of the crystallization dynamics during condensation and evaporation revealed that, for the basal face, both processes are highly activated, and in particular cubic ice is formed during condensation, producing stacking-disordered ice. The basal and primary prismatic surfaces of ice Ih were investigated at different temperatures and at their corresponding equilibrium vapor pressures. Our results show that the region known as QLL can be interpreted as the outermost layers of the solid where a partial melting takes place. Solid islands in the nanometer length scale are surrounded by interconnected liquid areas, generating a bidimensional nanophase segregation that spans throughout the entire width of the outermost layer even at 250 K. Two approaches were adopted to quantify the QLL and discussed in light of their ability to reflect this nanophase segregation phenomena. Our results in the μVT ensemble were compared with NPT and NVT simulations for two system sizes. No significant differences were found between the results as a consequence of model system size or of the working ensemble. Nevertheless, certain advantages of performing μVT simulations in order to reproduce the experimental situation are highlighted. On the one hand, the QLL thickness measured out of equilibrium might be affected because of crystallization being slower than condensation. On the other, preliminary simulations of AFM

  16. Transitional and turbulent boundary layer with heat transfer

    Science.gov (United States)

    Wu, Xiaohua; Moin, Parviz

    2010-08-01

    We report on our direct numerical simulation of an incompressible, nominally zero-pressure-gradient flat-plate boundary layer from momentum thickness Reynolds number 80-1950. Heat transfer between the constant-temperature solid surface and the free-stream is also simulated with molecular Prandtl number Pr=1. Skin-friction coefficient and other boundary layer parameters follow the Blasius solutions prior to the onset of turbulent spots. Throughout the entire flat-plate, the ratio of Stanton number and skin-friction St/Cf deviates from the exact Reynolds analogy value of 0.5 by less than 1.5%. Mean velocity and Reynolds stresses agree with experimental data over an extended turbulent region downstream of transition. Normalized rms wall-pressure fluctuation increases gradually with the streamwise growth of the turbulent boundary layer. Wall shear stress fluctuation, τw,rms'+, on the other hand, remains constant at approximately 0.44 over the range, 800spots are tightly packed with numerous hairpin vortices. With the advection and merging of turbulent spots, these young isolated hairpin forests develop into the downstream turbulent region. Isosurfaces of temperature up to Reθ=1900 are found to display well-resolved signatures of hairpin vortices, which indicates the persistence of the hairpin forests.

  17. Regional strain variations in the human patellar tendon.

    Science.gov (United States)

    Pearson, Stephen J; Ritchings, Tim; Mohamed, Azlan S A

    2014-07-01

    Characteristics of localized tendon strain in vivo are largely unknown. The present study examines local tendon strain between the deep, middle, and surface structures at the proximal and distal aspects of the patellar tendon during ramped isometric contractions. Male subjects (age 28.0 ± 6.3 yr) were examined for patellar tendon excursion (anterior, midsection, and posterior) during ramped isometric voluntary contractions using real-time B-mode ultrasonography and dynamometry. Regional tendon excursion measurements were compared using an automated pixel tracking method. Strain was determined from the tendon delta length normalized to initial/resting segment length. Strain increased from 10% to 100% of force for all regions. Significantly greater mean strain was seen for the anterior proximal region compared to the posterior and mid layer of the tendon (7.5% ± 1.1% vs 3.7% ± 0.5% vs 5.5% ± 1.0%; P < 0.05). Similarly, the distal posterior region showed greater mean strain compared to the mid and anterior regions (7.9% ± 0.6% vs 5.0% ± 0.6% vs 5.4% ± 0.6%; P < 0.05). Relative changes in strain differences from 50% to 100% of force for the proximal region were greatest for the anterior to midline regions (4.6% ± 0.6% and 5.6% ± 0.6%, respectively) and those for the distal region were also greatest for the anterior to midline regions (4.4% ± 0.2% and 5.3% ± 0.2%, respectively). The largest mean strain for the proximal region was at the anterior layer (7.5% ± 1.1%) and that for the distal tendon region was at the posterior layer (7.9% ± 0.9%). This study shows significant regional differences in strain during ramped isometric contractions for the patellar tendon. Lower proximal strains in the posterior tendon compared to the anterior region may be associated with the suggestion of "stress shielding" as an etiological factor in insertional tendinopathy.

  18. Drying of a tape-cast layer: Numerical investigation of influencing parameters

    DEFF Research Database (Denmark)

    Jabbaribehnam, Mirmasoud; Shojaee Nasirabadi, Parizad; Jambhekar, V. A.

    2017-01-01

    , the equivalent diameter of particles of the porous medium, dp, the porosity of the porous medium, φ the initial temperature in the free-flow region, Tff, and the initial temperature in the porous-medium region, Tpm, on the characteristic drying curves of a thin ceramic layer. We, moreover, conduct a statistical...

  19. Importance of layer thermal conductivity on the sharpness of patterns produced by laser interference

    Energy Technology Data Exchange (ETDEWEB)

    Peláez, R.J., E-mail: rpelaez@io.cfmac.csic.es [Laser Processing Group, Instituto de Optica, CSIC, Serrano 121, 28006 Madrid (Spain); Afonso, C.N. [Laser Processing Group, Instituto de Optica, CSIC, Serrano 121, 28006 Madrid (Spain); Škereň, M. [Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Brehova 7, 115 19 Prague 1 (Czech Republic); Bulíř, J. [Institute of Physics, ASCR, v.v.i., Na Slovance 2, Prague (Czech Republic)

    2016-06-30

    Highlights: • Temperature profile matches laser intensity profile in poor thermally conducting layers. • Patterns produced in poor thermally conducting layers have sharp interfaces. • Lateral heat flow smears the temperature profile in thermally conducting layers. • Both liquid and solid state dewetting occurs upon patterning thermally conducting layers. • The thermal conductivity of layers limits the minimum period achievable. - Abstract: In this work, we compare patterns produced in Ag layers having similar thickness in the range 8.3–10.8 nm but having different initial nanostructure, i.e. behaving either as discontinuous or continuous layers and thus having very different thermal conductivities. The patterns are produced by exposing a phase mask to an excimer laser operating at 193 nm and using a projection optics that leads to similar fringed patterns with periods in the range 6.3–6.7 μm. The layer breaks up into isolated NPs due to laser induced melting at the regions around the intensity maxima sites. The resulting fringes have sharp interfaces in the case of discontinuous layers while a variety of regions across the pattern with no sharp interfaces are produced in the case of continuous layers. The results show that while the temperature distribution across the pattern matches almost perfectly the laser beam intensity profile for the former case, it becomes smeared due to lateral heat flow for the latter case. These results provide evidences for significant heating at the intensity minima sites that lead to solid-state dewetting and will eventually limit the minimum period achievable in the case of continuous metal layers or thermally conducting layers.

  20. Boundary layer plasmas as a source for high-latitude, early afternoon, auroral arcs

    International Nuclear Information System (INIS)

    Lundin, R.; Evans, D.S.

    1985-02-01

    Simultaneous measurements of hot boundary layer plasma from PROGNOZ-7 and particle precipitation from the TIROS/NOAA satellite in nearly magnetically conjugate regions have been used to study the dynamo process responsible for the formation of high latitude, early afternoon, auroral arcs. Characteristic for the PROGNOZ-7 observations in the dayside boundary layer at high latitudes is the frequent occurrence of regions with injected magnetosheath plasma embedded in a 'halo' of antisunward flowing magnetosphere plasma. The injected magnetosheath plasma have several features which indicate that it also acts as a local source of EMF in the boundary layer. The process resembles that of a local MHD dynamo driven by the excess drift velocity of the injected magnetosheath plasma relative to the background magnetospheric plasma. The dynamo region is capable of driving fielc-aligned currents that couple to the ionosphere, where the upward current is associated with the high latitude auroral arcs. We demonstrate that the large-scale morphology as well as the detailed data intercomparison between PROGNOZ-7 and TIROS-N both agree well with a local injection of magnetosheath plasma into the dayside boundary layer as the main dynamo process powering the high-latitude, early afternoon auroral arcs. (Author)

  1. On the dynamics of relativistic multi-layer spherical shell systems

    Energy Technology Data Exchange (ETDEWEB)

    Gaspar, Merse E; Racz, Istvan, E-mail: merse@rmki.kfki.hu, E-mail: iracz@rmki.kfki.hu [RMKI, H-1121 Budapest, Konkoly Thege Miklos ut 29-33, Budapest (Hungary)

    2011-04-21

    The relativistic time evolution of multi-layer spherically symmetric shell systems-consisting of infinitely thin shells separated by vacuum regions-is examined. Whenever two shells collide the evolution is continued with the assumption that the collision is totally transparent. The time evolution of various multi-layer shell systems-comprising large number of shells thereby mimicking the behavior of a thick shell making it possible to study the formation of acoustic singularities-is analyzed numerically and compared in certain cases to the corresponding Newtonian time evolution. The analytic setup is chosen such that the developed code is capable of following the evolution even inside the black hole region. This, in particular, allowed us to investigate the mass inflation phenomenon in the chosen framework.

  2. Atomic layer deposition and post-growth thermal annealing of ultrathin MoO3 layers on silicon substrates: Formation of surface nanostructures

    Science.gov (United States)

    Liu, Hongfei; Yang, Ren Bin; Yang, Weifeng; Jin, Yunjiang; Lee, Coryl J. J.

    2018-05-01

    Ultrathin MoO3 layers have been grown on Si substrates at 120 °C by atomic layer deposition (ALD) using molybdenum hexacarbonyl [Mo(CO)6] and ozone (O3) as the Mo- and O-source precursors, respectively. The ultrathin films were further annealed in air at Tann = 550-750 °C for 15 min. Scanning-electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy have been employed to evaluate the morphological and elemental properties as well as their evolutions upon annealing of the thin films. They revealed an interfacial SiOx layer in between the MoO3 layer and the Si substrate; this SiOx layer converted into SiO2 during the annealing; and the equivalent thickness of the MoO3 (SiO2) layer decreased (increased) with the increase in Tann. Particles with diameters smaller than 50 nm emerged at Tann = 550 °C and their sizes (density) were reduced (increased) by increasing Tann to 650 °C. A further increase of Tann to 750 °C resulted in telephone-cord-like MoO3 structures, initiated from isolated particles on the surface. These observations have been discussed and interpreted based on temperature-dependent atomic interdiffusions, surface evaporations, and/or melting of MoO3, which shed new light on ALD MoO3 towards its electronic applications.

  3. Numerical modelling of evaporation in a ceramic layer in the tape casting process

    DEFF Research Database (Denmark)

    Jabbaribehnam, Mirmasoud; Jambhekar, V. A.; Hattel, Jesper Henri

    2016-01-01

    Evaporation of water from a ceramic layer is a key phenomenon in the drying process for the manufacturing of tape cast ceramics. This process contains mass, momentum and energy exchange between the porous medium and the free-flow region. In order to analyze such interaction processes, a Represent......Evaporation of water from a ceramic layer is a key phenomenon in the drying process for the manufacturing of tape cast ceramics. This process contains mass, momentum and energy exchange between the porous medium and the free-flow region. In order to analyze such interaction processes...

  4. Synthesis, characterization and application of two-dimensional layered metal hydroxides for environmental remediation purposes

    Science.gov (United States)

    Machingauta, Cleopas

    Two-dimensional layered nano composites, which include layered double hydroxides (LDHs), hydroxy double salts (HDSs) and layered hydroxide salts (LHSs) are able to intercalate different molecular species within their gallery space. These materials have a tunable structural composition which has made them applicable as fire retardants, adsorbents, catalysts, catalyst support materials, and ion exchangers. Thermal treatment of these materials results in destruction of the layers and formation of mixed metal oxides (MMOs) and spinels. MMOs have the ability to adsorb anions from solution and may also regenerate layered structures through a phenomenon known as memory effect. Zinc-nickel hydroxy nitrate was used for the uptake of a series of halogenated acetates (HAs). HAs are pollutants introduced into water systems as by-products of water chlorination and pesticide degradation; their sequestration from water is thus crucial. Optimization of layered materials for controlled uptake requires an understanding of their ion-exchange kinetics and thermodynamics. Exchange kinetics of these anions was monitored using ex-situ PXRD, UV-vis, HPLC and FTIR. It was revealed that exchange rates and uptake efficiencies are related to electronic spatial extents and the charge on carboxyl-oxygen atoms. In addition, acetate and nitrate-based HDSs were used to explore how altering the hydroxide layer affects uptake of acetate/nitrate ions. Changing the metal identities affects the interaction of the anions with the layers. From FTIR, we observed that nitrates coordinate in a D3h and Cs/C 2v symmetry; the nitrates in D3h symmetry were easily exchangeable. Interlayer hydrogen bonding was also revealed to be dependent on metal identity. Substituting divalent cations with trivalent cations produces materials with a higher charge density than HDSs and LHSs. A comparison of the uptake efficiency of zinc-aluminum, zinc-gallium and zinc-nickel hydroxy nitrates was performed using trichloroacetic

  5. Optimizing pentacene thin-film transistor performance: Temperature and surface condition induced layer growth modification.

    Science.gov (United States)

    Lassnig, R; Hollerer, M; Striedinger, B; Fian, A; Stadlober, B; Winkler, A

    2015-11-01

    In this work we present in situ electrical and surface analytical, as well as ex situ atomic force microscopy (AFM) studies on temperature and surface condition induced pentacene layer growth modifications, leading to the selection of optimized deposition conditions and entailing performance improvements. We prepared p ++ -silicon/silicon dioxide bottom-gate, gold bottom-contact transistor samples and evaluated the pentacene layer growth for three different surface conditions (sputtered, sputtered + carbon and unsputtered + carbon) at sample temperatures during deposition of 200 K, 300 K and 350 K. The AFM investigations focused on the gold contacts, the silicon dioxide channel region and the highly critical transition area. Evaluations of coverage dependent saturation mobilities, threshold voltages and corresponding AFM analysis were able to confirm that the first 3-4 full monolayers contribute to the majority of charge transport within the channel region. At high temperatures and on sputtered surfaces uniform layer formation in the contact-channel transition area is limited by dewetting, leading to the formation of trenches and the partial development of double layer islands within the channel region instead of full wetting layers. By combining the advantages of an initial high temperature deposition (well-ordered islands in the channel) and a subsequent low temperature deposition (continuous film formation for low contact resistance) we were able to prepare very thin (8 ML) pentacene transistors of comparably high mobility.

  6. The Atmospheric Boundary Layer

    Science.gov (United States)

    Garratt, J. R.

    1994-05-01

    A comprehensive and lucid account of the physics and dynamics of the lowest one to two kilometers of the Earth's atmosphere in direct contact with the Earth's surface, known as the atmospheric boundary layer (ABL). Dr. Garratt emphasizes the application of the ABL problems to numerical modeling of the climate, which makes this book unique among recent texts on the subject. He begins with a brief introduction to the ABL before leading to the development of mean and turbulence equations and the many scaling laws and theories that are the cornerstone of any serious ABL treatment. Modeling of the ABL is crucially dependent for its realism on the surface boundary conditions, so chapters four and five deal with aerodynamic and energy considerations, with attention given to both dry and wet land surfaces and the sea. The author next treats the structure of the clear-sky, thermally stratified ABL, including the convective and stable cases over homogeneous land, the marine ABL, and the internal boundary layer at the coastline. Chapter seven then extends this discussion to the cloudy ABL. This is particularly relevant to current research because the extensive stratocumulus regions over the subtropical oceans and stratus regions over the Arctic have been identified as key players in the climate system. In the final chapters, Dr. Garratt summarizes the book's material by discussing appropriate ABL and surface parameterization schemes in general circulation models of the atmosphere that are being used for climate stimulation.

  7. Intercalation of Si between MoS2 layers

    Directory of Open Access Journals (Sweden)

    Rik van Bremen

    2017-09-01

    Full Text Available We report a combined experimental and theoretical study of the growth of sub-monolayer amounts of silicon (Si on molybdenum disulfide (MoS2. At room temperature and low deposition rates we have found compelling evidence that the deposited Si atoms intercalate between the MoS2 layers. Our evidence relies on several experimental observations: (1 Upon the deposition of Si on pristine MoS2 the morphology of the surface transforms from a smooth surface to a hill-and-valley surface. The lattice constant of the hill-and-valley structure amounts to 3.16 Å, which is exactly the lattice constant of pristine MoS2. (2 The transitions from hills to valleys are not abrupt, as one would expect for epitaxial islands growing on-top of a substrate, but very gradual. (3 I(V scanning tunneling spectroscopy spectra recorded at the hills and valleys reveal no noteworthy differences. (4 Spatial maps of dI/dz reveal that the surface exhibits a uniform work function and a lattice constant of 3.16 Å. (5 X-ray photo-electron spectroscopy measurements reveal that sputtering of the MoS2/Si substrate does not lead to a decrease, but an increase of the relative Si signal. Based on these experimental observations we have to conclude that deposited Si atoms do not reside on the MoS2 surface, but rather intercalate between the MoS2 layers. Our conclusion that Si intercalates upon the deposition on MoS2 is at variance with the interpretation by Chiappe et al. (Adv. Mater. 2014, 26, 2096–2101 that silicon forms a highly strained epitaxial layer on MoS2. Finally, density functional theory calculations indicate that silicene clusters encapsulated by MoS2 are stable.

  8. A "continuity-index" for assessing ice-sheet dynamics from radar-sounded internal layers

    DEFF Research Database (Denmark)

    Karlsson, Nanna Bjørnholt; Rippin, David; Bingham, Robert G.

    2012-01-01

    Radio-echo sounding (RES) of polar icesheets reveals extensive internal layering. The degree of continuity of internal layering holds critical information about the ice-flow field, but previous analyses of this parameter have been limited to qualitative classifications. Here we present a new...... further support that the main trunk and tributaries are unlikely to have undergone substantial migration since the deposition of the internal layering. Significantly, our new method for analyzing internallayers is readily transferable across RES datasets, offering promise for data-led assessments of past...

  9. Stratigraphy and erosional landforms of layered deposits in Valles Marineris, Mars

    Science.gov (United States)

    Komatsu, G.; Geissler, P. E.; Strom, R. G.; Singer, R. B.

    1993-01-01

    Satellite imagery is used to identify stratigraphy and erosional landforms of 13 layered deposits in the Valles Marineris region of Mars (occurring, specifically, in Gangis, Juventae, Hebes, Ophir-Candor, Melas, and Capri-Eos Chasmata), based on albedo and erosional styles. Results of stratigraphic correlations show that the stratigraphy of layered deposits in the Hebes, Juventae, and Gangis Chasmata are not well correlated, indicating that at least these chasmata had isolated depositional environments resulting in different stratigraphic sequences. On the other hand, the layered deposits in Ophir-Candor and Melas Chasmata appear to have been connected in each chasma. Some of the layered deposits display complexities which indicate changes in space and time in the dominant source materials.

  10. Contours, This Layer was derived from the USGS National Elevation Dataset (NED) based on 7.5 minute Digital Elevation Model (DEM) image files., Published in 1999, 1:24000 (1in=2000ft) scale, Atlanta Regional Commission.

    Data.gov (United States)

    NSGIC Regional | GIS Inventory — Contours dataset current as of 1999. This Layer was derived from the USGS National Elevation Dataset (NED) based on 7.5 minute Digital Elevation Model (DEM) image...

  11. Vanishing stick-slip friction in few-layer graphenes: the thickness effect.

    Science.gov (United States)

    Xu, Liang; Ma, Tian-Bao; Hu, Yuan-Zhong; Wang, Hui

    2011-07-15

    We report the thickness dependence of intrinsic friction in few-layer graphenes, adopting molecular dynamics simulations. The friction force drops dramatically with decreasing number of layers and finally approaches zero with two or three layers. The results, which are robust over a wide range of temperature, shear velocity, and pressure are quantitatively explained by a theoretical model with regard to lateral stiffness, slip length, and maximum lateral force, which could provide a new conceptual framework for understanding stick-slip friction. The results reveal the crucial role of the dimensional effect in nanoscale friction, and could be helpful in the design of graphene-based nanodevices.

  12. Controlled fabrication of Si nanocrystal delta-layers in thin SiO2 layers by plasma immersion ion implantation for nonvolatile memories

    International Nuclear Information System (INIS)

    Bonafos, C.; Ben-Assayag, G.; Groenen, J.; Carrada, M.; Spiegel, Y.; Torregrosa, F.; Normand, P.; Dimitrakis, P.; Kapetanakis, E.; Sahu, B. S.; Slaoui, A.

    2013-01-01

    Plasma Immersion Ion Implantation (PIII) is a promising alternative to beam line implantation to produce a single layer of nanocrystals (NCs) in the gate insulator of metal-oxide semiconductor devices. We report herein the fabrication of two-dimensional Si-NCs arrays in thin SiO 2 films using PIII and rapid thermal annealing. The effect of plasma and implantation conditions on the structural properties of the NC layers is examined by transmission electron microscopy. A fine tuning of the NCs characteristics is possible by optimizing the oxide thickness, implantation energy, and dose. Electrical characterization revealed that the PIII-produced-Si NC structures are appealing for nonvolatile memories

  13. Lagrangian mixed layer modeling of the western equatorial Pacific

    Science.gov (United States)

    Shinoda, Toshiaki; Lukas, Roger

    1995-01-01

    Processes that control the upper ocean thermohaline structure in the western equatorial Pacific are examined using a Lagrangian mixed layer model. The one-dimensional bulk mixed layer model of Garwood (1977) is integrated along the trajectories derived from a nonlinear 1 1/2 layer reduced gravity model forced with actual wind fields. The Global Precipitation Climatology Project (GPCP) data are used to estimate surface freshwater fluxes for the mixed layer model. The wind stress data which forced the 1 1/2 layer model are used for the mixed layer model. The model was run for the period 1987-1988. This simple model is able to simulate the isothermal layer below the mixed layer in the western Pacific warm pool and its variation. The subduction mechanism hypothesized by Lukas and Lindstrom (1991) is evident in the model results. During periods of strong South Equatorial Current, the warm and salty mixed layer waters in the central Pacific are subducted below the fresh shallow mixed layer in the western Pacific. However, this subduction mechanism is not evident when upwelling Rossby waves reach the western equatorial Pacific or when a prominent deepening of the mixed layer occurs in the western equatorial Pacific or when a prominent deepening of the mixed layer occurs in the western equatorial Pacific due to episodes of strong wind and light precipitation associated with the El Nino-Southern Oscillation. Comparison of the results between the Lagrangian mixed layer model and a locally forced Eulerian mixed layer model indicated that horizontal advection of salty waters from the central Pacific strongly affects the upper ocean salinity variation in the western Pacific, and that this advection is necessary to maintain the upper ocean thermohaline structure in this region.

  14. Microstructure and Mechanical Properties of Three-Layer TIG-Welded 2219 Aluminum Alloys with Dissimilar Heat Treatments

    Science.gov (United States)

    Zhang, Dengkui; Li, Quan; Zhao, Yue; Liu, Xianli; Song, Jianling; Wang, Guoqing; Wu, Aiping

    2018-05-01

    2219-C10S and 2219-CYS aluminum alloys are 2219 aluminum alloys with different heat treatment processes, and they have been widely used in the aerospace industry. In the present study, 2219-C10S and 2219-CYS aluminum alloys were butt-welded by three-layer tungsten inert gas arc welding (with the welding center of the third layer shifted toward the CYS side), and the microstructure characteristics and mechanical properties of the welded joint were investigated. The lamellar θ' phases, the bulk or rod θ phases, and the coarse rod-shaped or pancake-shaped Al-Cu-Fe-Mn phases coexisted in the two aluminum alloys. The Cu content of the α-Al matrix and the distribution of eutectic structures of different welding layers in the weld zone (WZ) were varied, implying that the segregation degrees of the Cu element were different due to the different welding thermal cycles in different welding layers. The microhardness values of the CYS side were much higher than those of the C10S side in each region on both sides of the joint. The tensile test deformation was concentrated mainly in the regions of WZ and the over aged zone (OAZ), where the microhardness values were relatively low. The main deformation concentrated region was transferred from the CYS side to the C10S side with the increase in the tensile load during the tensile test. The fracture behavior of the tensile test showed that the macroscopic crack initiated near the front weld toe had gone through the crack blunt region, the shear fracture region of the partially melted zone (PMZ), and the shear fracture region of OAZ. Meanwhile, the fracture characteristics gradually evolved from brittle to ductile. The concentrated stress and the dense eutectic structure in the region near the front weld toe of the C10S side contributed to the fracture of the joint. The shift of the welding center of the third layer to the CYS side resulted in two effects: (i) the microhardness values from the middle layer to the top layer in the

  15. State diagram of spin-torque oscillator with perpendicular reference layer and planar field generation layer

    Directory of Open Access Journals (Sweden)

    Mengwei Zhang

    2015-06-01

    Full Text Available The state diagram of spin-torque oscillator (STO with perpendicular reference layer (REF and planar field generation layer (FGL was studied by a macrospin model and a micro-magnetic model. The state diagrams are calculated versus the current density, external field and external field angle. It was found that the oscillation in FGL could be controlled by current density combined with external field so as to achieve a wide frequency range. An optimized current and applied field region was given for microwave assisted magnetic recording (MAMR, considering both frequency and output field oscillation amplitude. The results of the macro-spin model were compared with those of the micro-magnetic model. The macro-spin model was qualitatively different from micro-magnetics and experimental results when the current density was large and the FGL was non-uniform.

  16. Traffic Analysis Zones, This Layer was created by ARC's Transportation Planning Division to identify Traffic Analysis Zones (TAZs) in the 20-county Atlanta Region. These TAZs represent the geography used in the ongoing transportation modeling for the Envision 6 forecast series (, Published in 2006, 1:100000 (1in=8333ft) scale, Atlanta Regional Commission.

    Data.gov (United States)

    NSGIC Regional | GIS Inventory — Traffic Analysis Zones dataset current as of 2006. This Layer was created by ARC's Transportation Planning Division to identify Traffic Analysis Zones (TAZs) in the...

  17. Change of Retinal Nerve Layer Thickness in Non-Arteritic Anterior Ischemic Optic Neuropathy Revealed by Fourier Domain Optical Coherence Tomography.

    Science.gov (United States)

    Han, Mei; Zhao, Chen; Han, Quan-Hong; Xie, Shiyong; Li, Yan

    2016-08-01

    To examine the changes of non-arteritic anterior ischemic optic neuropathy (NAION) by serial morphometry using Fourier domain optical coherence tomography (FD-OCT). Retrospective study in patients with newly diagnosed NAION (n=33, all unilateral) and controls (n=75 unilateral NAION patients with full contralateral eye vision) who underwent FD-OCT of the optic disk, optic nerve head (ONH), and macula within 1 week of onset and again 1, 3, 6, and 12 months later. The patients showed no improvement in vision during follow-up. Within 1 week of onset, all NAION eyes exhibited severe ONH fiber crowding and peripapillary retinal nerve fiber layer (RNFL) edema. Four had subretinal fluid accumulation and 12 had posterior vitreous detachment (PVD) at the optic disc surface. Ganglion cell complex (GCC) and RNFL thicknesses were reduced at 1 and 3 months (p < 0.05), with no deterioration thereafter. Initial RNFL/GCC contraction magnitude in the superior hemisphere correlated with the severity of inferior visual field deficits. NAION progression is characterized by an initial phase of accelerated RNFL and GCC deterioration. These results reveal that the kinetic change of neural retina in NAION and may have implication on the time window for treatment of NAION. FD-OCT is useful in the evaluation of NAION.

  18. Experiments in a boundary layer subjected to free stream turbulence. Part 1: Boundary layer structure and receptivity

    International Nuclear Information System (INIS)

    Westin, K.J.A.; Boiko, A.V.; Klingmann, B.G.B.; Kozlov, V.V.; Alfredsson, P.H.

    1993-12-01

    The modification of the mean and fluctuating characteristics of a flat plate boundary layer subjected to nearly isotropic free stream turbulence (FST) is studied experimentally using hot-wire anemometry. The study is focussed on the region upstream of the transition onset, where the fluctuations inside the boundary layer are dominated by elongated flow structures which grow downstream both in amplitude and length. Their downstream development and scaling is investigated, and the results are compared to those obtained by previous authors. This allows some conclusions about the parameters which are relevant for the modelling of the transition process. The mechanisms underlying the transition process and the relative importance of the Tollmien-Schlichting wave instability in this flow are treated in an accompanying paper. 25 refs

  19. Vegetation mapping with satellite data of the Forsmark and Tierp regions

    Energy Technology Data Exchange (ETDEWEB)

    Boresjoe-Bronge, Laine; Wester, Kjell [SwedPower, Stockholm (Sweden)

    2002-04-01

    SKB (Swedish Nuclear Fuel and Waste Management Co) performs a siting program for deep repository of spent nuclear fuel that includes survey of three potential sites. The SKB siting process has now reached the site investigation phase. There are several fields of investigations performed in this phase. One of them is description of the surface ecosystems. The surface ecosystems are mapped both on a regional (50-100 km{sup 2} ) and a local level (1 km{sup 2} ). Two inventory methods are used, remote sensing (satellite data/aerial photographs) for the regional level, and field inventory for the detailed level. As a part of the surface ecosystem characterisation on the regional level vegetation mapping using satellite data has been performed over the three potential deep depository sites, Forsmark, Tierp and Oskarshamn. The user requirements for the vegetation mapping of the potential sites are the following: Dominated species in the tree layer, shrub layer, field layer and ground layer shall be described both on regional and local level; Dominated species in all layers shall be quantified regarding share and percentage of ground cover, or absence of cover (vegetation free ground); The regional and the local inventory shall have identical or comparable classification systems; The classification system and the method used shall make it possible to scale the results from local to regional level and vice versa; The produced layers shall be presented in digital form and make it possible to model biomass and turnover of organic matter (carbon, nutrients, water); The produced information shall in a first phase be of use for planning and for making nature and environmental considerations. Data sources used in the study include geo-referenced SPOT4 XI data (20 m ground resolution), geo-referenced Landsat TM data (30 m ground resolution), soil type data, topographic map data and colour infrared aerial photographs. The production of vegetation layers has been carried out in two

  20. Vegetation mapping with satellite data of the Forsmark and Tierp regions

    International Nuclear Information System (INIS)

    Boresjoe-Bronge, Laine; Wester, Kjell

    2002-04-01

    SKB (Swedish Nuclear Fuel and Waste Management Co) performs a siting program for deep repository of spent nuclear fuel that includes survey of three potential sites. The SKB siting process has now reached the site investigation phase. There are several fields of investigations performed in this phase. One of them is description of the surface ecosystems. The surface ecosystems are mapped both on a regional (50-100 km 2 ) and a local level (1 km 2 ). Two inventory methods are used, remote sensing (satellite data/aerial photographs) for the regional level, and field inventory for the detailed level. As a part of the surface ecosystem characterisation on the regional level vegetation mapping using satellite data has been performed over the three potential deep depository sites, Forsmark, Tierp and Oskarshamn. The user requirements for the vegetation mapping of the potential sites are the following: Dominated species in the tree layer, shrub layer, field layer and ground layer shall be described both on regional and local level; Dominated species in all layers shall be quantified regarding share and percentage of ground cover, or absence of cover (vegetation free ground); The regional and the local inventory shall have identical or comparable classification systems; The classification system and the method used shall make it possible to scale the results from local to regional level and vice versa; The produced layers shall be presented in digital form and make it possible to model biomass and turnover of organic matter (carbon, nutrients, water); The produced information shall in a first phase be of use for planning and for making nature and environmental considerations. Data sources used in the study include geo-referenced SPOT4 XI data (20 m ground resolution), geo-referenced Landsat TM data (30 m ground resolution), soil type data, topographic map data and colour infrared aerial photographs. The production of vegetation layers has been carried out in two steps. In