WorldWideScience

Sample records for surface area dependent

  1. Size-Dependent Specific Surface Area of Nanoporous Film Assembled by Core-Shell Iron Nanoclusters

    Directory of Open Access Journals (Sweden)

    Jiji Antony

    2006-01-01

    Full Text Available Nanoporous films of core-shell iron nanoclusters have improved possibilities for remediation, chemical reactivity rate, and environmentally favorable reaction pathways. Conventional methods often have difficulties to yield stable monodispersed core-shell nanoparticles. We produced core-shell nanoclusters by a cluster source that utilizes combination of Fe target sputtering along with gas aggregations in an inert atmosphere at 7∘C. Sizes of core-shell iron-iron oxide nanoclusters are observed with transmission electron microscopy (TEM. The specific surface areas of the porous films obtained from Brunauer-Emmett-Teller (BET process are size-dependent and compared with the calculated data.

  2. Correlating humidity-dependent ionically conductive surface area with transport phenomena in proton-exchange membranes.

    Science.gov (United States)

    He, Qinggang; Kusoglu, Ahmet; Lucas, Ivan T; Clark, Kyle; Weber, Adam Z; Kostecki, Robert

    2011-10-13

    The objective of this effort was to correlate the local surface ionic conductance of a Nafion 212 proton-exchange membrane with its bulk and interfacial transport properties as a function of water content. Both macroscopic and microscopic proton conductivities were investigated at different relative humidity levels, using direct-current voltammetry and current-sensing atomic force microscopy (CSAFM). We were able to identify small ion-conducting domains that grew with humidity at the surface of the membrane. Numerical analysis of the surface ionic conductance images recorded at various relative humidity levels helped determine the fractional area of ion-conducting active sites. A simple square-root relationship between the fractional conducting area and observed interfacial mass-transport resistance was established. Furthermore, the relationship between the bulk ionic conductivity and surface ionic conductance pattern of the Nafion membrane was examined.

  3. Correlating Humidity-Dependent Ionically Conductive Surface Area with Transport Phenomena in Proton-Exchange Membranes

    Energy Technology Data Exchange (ETDEWEB)

    He, Qinggang; Kusoglu, Ahmet; Lucas, Ivan T.; Clark, Kyle; Weber, Adam Z.; Kostecki, Robert

    2011-08-01

    The objective of this effort was to correlate the local surface ionic conductance of a Nafion? 212 proton-exchange membrane with its bulk and interfacial transport properties as a function of water content. Both macroscopic and microscopic proton conductivities were investigated at different relative humidity levels, using electrochemical impedance spectroscopy and current-sensing atomic force microscopy (CSAFM). We were able to identify small ion-conducting domains that grew with humidity at the surface of the membrane. Numerical analysis of the surface ionic conductance images recorded at various relative humidity levels helped determine the fractional area of ion-conducting active sites. A simple square-root relationship between the fractional conducting area and observed interfacial mass-transport resistance was established. Furthermore, the relationship between the bulk ionic conductivity and surface ionic conductance pattern of the Nafion? membrane was examined.

  4. Macrostructure-dependent photocatalytic property of high-surface-area porous titania films

    Directory of Open Access Journals (Sweden)

    T. Kimura

    2014-11-01

    Full Text Available Porous titania films with different macrostructures were prepared with precise control of condensation degree and density of the oxide frameworks in the presence of spherical aggregates of polystyrene-block-poly(oxyethylene (PS-b-PEO diblock copolymer. Following detailed explanation of the formation mechanisms of three (reticular, spherical, and large spherical macrostructures by the colloidal PS-b-PEO templating, structural variation of the titania frameworks during calcination were investigated by X-ray diffraction and X-ray photoelectron spectroscopy. Then, photocatalytic performance of the macroporous titania films was evaluated through simple degradation experiments of methylene blue under an UV irradiation. Consequently, absolute surface area of the film and crystallinity of the titania frameworks were important for understanding the photocatalytic performance, but the catalytic performance can be improved further by the macrostructural design that controls diffusivity of the targeted molecules inside the film and their accessibility to active sites.

  5. Cortical thickness, surface area, and volume of the brain reward system in alcohol dependence: relationships to relapse and extended abstinence.

    Science.gov (United States)

    Durazzo, Timothy C; Tosun, Duygu; Buckley, Shannon; Gazdzinski, Stefan; Mon, Anderson; Fryer, Susanna L; Meyerhoff, Dieter J

    2011-06-01

    At least 60% of those treated for an alcohol use disorder will relapse. Empirical study of the integrity of the brain reward system (BRS) is critical to understanding the mechanisms of relapse as this collection of circuits is implicated in the development and maintenance of all forms of addictive disorders. This study compared thickness, surface area, and volume in neocortical components of the BRS among nonsmoking light-drinking controls (controls), individuals who remained abstinent and those who relapsed after treatment. Seventy-five treatment-seeking alcohol-dependent individuals (abstinent for 7±3 days) and 43 controls completed 1.5T proton magnetic resonance imaging studies. Parcellated morphological data were obtained for following bilateral components of the BRS: rostral and caudal anterior cingulate cortex, insula, medial and lateral orbitofrontal cortex (OFC), rostral and caudal middle and superior frontal gyri, amygdala and hippocampus as well as for 26 other bilateral neocortical regions. Alcohol-dependent participants were followed over 12-months after baseline study and were classified as abstainers (no alcohol consumption; n=24) and relapsers (any alcohol consumption; n=51) at follow-up. Relapsers and abstainers demonstrated lower cortical thickness in the vast majority of BRS regions as well as lower global thickness compared to controls. Relapsers had lower total BRS surface area than both controls and abstainers, but abstainers were not significantly different from controls on any surface area measure. Relapsers demonstrated lower volumes than controls in the majority of regions, while abstainers showed lower volumes than controls in the superior frontal gyrus, insula, amygdala, and hippocampus, bilaterally. Relapsers exhibited smaller volumes than abstainers in the right rostral middle and caudal middle frontal gyri and the lateral OFC, bilaterally. In relapsers, lower baseline volumes and surface areas in multiple regions were associated with

  6. Ice formation via deposition nucleation on mineral dust and organics: dependence of onset relative humidity on total particulate surface area

    International Nuclear Information System (INIS)

    Kanji, Zamin A; Florea, Octavian; Abbatt, Jonathan P D

    2008-01-01

    We present ice nucleation results for Arizona test dust, kaolinite, montmorillonite, silica, silica coated with a hydrophobic octyl chain, oxalic acid dihydrate, Gascoyne leonardite (a humic material), and Aldrich humic acid (sodium salt). The focus was on deposition mode nucleation below water saturation at 233 K. Particles were deposited onto a hydrophobic cold stage by atomization of a slurry/solution and exposed to a constant partial pressure of water vapor. By lowering the temperature of the stage, the relative humidity with respect to ice (RH i ) was gradually increased until ice nucleation was observed using digital photography. Different numbers of particles were deposited onto the cold stage by varying the atomization solution concentration and deposition time. For the same total particulate surface area, mineral dust particles nucleated ice at lower supersaturations than all other materials. The most hydrophobic materials, i.e. Gascoyne leonardite and octyl silica, were the least active. For our limit of detection of one ice crystal, the ice onset RH i values were dependent on the total surface area of the particulates, indicating that no unique threshold RH i for ice nucleation prevails

  7. High surface area calcite

    Science.gov (United States)

    Schultz, L. N.; Andersson, M. P.; Dalby, K. N.; Müter, D.; Okhrimenko, D. V.; Fordsmand, H.; Stipp, S. L. S.

    2013-05-01

    Calcite (CaCO3) is important in many fields—in nature, because it is a component of aquifers, oil reservoirs and prospective CO2 storage sites, and in industry, where it is used in products as diverse as paper, toothpaste, paint, plastic and aspirin. It is difficult to obtain high purity calcite with a high surface area but such material is necessary for industrial applications and for fundamental calcite research. Commercial powder is nearly always contaminated with growth inhibitors such as sugars, citrate or pectin and most laboratory synthesis methods deliver large precipitates, often containing vaterite or aragonite. To address this problem, we (i) adapted the method of carbonating a Ca(OH)2 slurry with CO2 gas to develop the first simple, cheap, safe and reproducible procedure using common laboratory equipment, to obtain calcite that reproducibly had a surface area of 14-17 m2/g and (ii) conducted a thorough characterization of the product. Scanning electron microscopy (SEM) revealed nanometer scale, rhombohedral crystals. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR) confirmed highly crystalline, pure calcite that more closely resembles the dimensions of the biogenic calcite produced by algae in coccoliths than other methods for synthesizing calcite. We suggest that this calcite is useful when purity and high surface area are important.

  8. Cerebral extraction of N-13 ammonia: its dependence on cerebral blood flow and capillary permeability, surface area product

    International Nuclear Information System (INIS)

    Phelps, M.E.; Huang, S.C.; Kuhl, D.E.; Hoffman, E.J.; Slin, C.

    1979-01-01

    13 N-labeled ammonia was used to investigate: (1) the cerebral extraction and clearance of ammonia; (2) the mechanicsm by which capillaries accommodate changes in cerebral blood flow (CBF); and (3) its use for the measure of CBF. This was investigated by measuring the single pass extraction of 13 NH 3 in rhesus monkeys during P/sub a/CO 2 induced changes in CBF, and with dog studies using in vitro tissue counting techniques to examine 13 NH 3 extraction in gray and white matter, mixed tissue, and cerebellum during variations in CBF produced by combinations of embolization, local brain compression, and changes in P/sub a/CO 2 . The single pass extraction fraction of 13 NH 3 varied from about 70 to 20% over a CBF range of 12 to 140cc/min/100gms. Capillary permeability-surface area product (PS) estimates from this data and the dog experiments show PS increasing with CBF. The magnitude and rate of increase in PS with CBF was highest in gray matter > mixed tissue > white matter. Tissue extraction of 13 NH 3 vs CBF relationship was best described by a unidirectional transport model in which CBF increases by both recruitment of capillaries and by increases of blood velocity in open capillaries. Glutamine synthetase, which incorporates 13 NH 3 into glutamine, appears to be anatomically located in astrocytes in general and specifically in the astrocytic pericapillary end-feet that are in direct contact with gray and white matter capillaries. The net 13 NH 3 extraction subsequent to an i.v. injection increases nonlinearly with CBF. Doubling or halving basal CBF produced from 40 to 50% changes in the 13 N tissue concentrations with further increases in CBF associated with progressively smaller changes in 13 N concentrations. 13 NH 3 appears to be a good tracer for the detection of cerebral ischemia with positron tomography but exhibits a poor response at high values of CBF

  9. Cerebral extraction of N-13 ammonia: its dependence on cerebral blood flow and capillary permeability, surface area product. [Dogs; monkeys

    Energy Technology Data Exchange (ETDEWEB)

    Phelps, M.E.; Huang, S.C.; Kuhl, D.E.; Hoffman, E.J.; Slin, C.

    1979-01-01

    /sup 13/N-labeled ammonia was used to investigate: (1) the cerebral extraction and clearance of ammonia; (2) the mechanicsm by which capillaries accommodate changes in cerebral blood flow (CBF); and (3) its use for the measure of CBF. This was investigated by measuring the single pass extraction of /sup 13/NH/sub 3/ in rhesus monkeys during P/sub a/CO/sub 2/ induced changes in CBF, and with dog studies using in vitro tissue counting techniques to examine /sup 13/NH/sub 3/ extraction in gray and white matter, mixed tissue, and cerebellum during variations in CBF produced by combinations of embolization, local brain compression, and changes in P/sub a/CO/sub 2/. The single pass extraction fraction of /sup 13/NH/sub 3/ varied from about 70 to 20% over a CBF range of 12 to 140cc/min/100gms. Capillary permeability-surface area product (PS) estimates from this data and the dog experiments show PS increasing with CBF. The magnitude and rate of increase in PS with CBF was highest in gray matter > mixed tissue > white matter. Tissue extraction of /sup 13/NH/sub 3/ vs CBF relationship was best described by a unidirectional transport model in which CBF increases by both recruitment of capillaries and by increases of blood velocity in open capillaries. Glutamine synthetase, which incorporates /sup 13/NH/sub 3/ into glutamine, appears to be anatomically located in astrocytes in general and specifically in the astrocytic pericapillary end-feet that are in direct contact with gray and white matter capillaries. The net /sup 13/NH/sub 3/ extraction subsequent to an i.v. injection increases nonlinearly with CBF. Doubling or halving basal CBF produced from 40 to 50% changes in the /sup 13/N tissue concentrations with further increases in CBF associated with progressively smaller changes in /sup 13/N concentrations. /sup 13/NH/sub 3/ appears to be a good tracer for the detection of cerebral ischemia with positron tomography but exhibits a poor response at high values of CBF.

  10. On semiautomatic estimation of surface area

    DEFF Research Database (Denmark)

    Dvorak, J.; Jensen, Eva B. Vedel

    2013-01-01

    . For convex particles, the estimator is equal to four times the area of the support set (flower set) of the particle transect. We study the statistical properties of the flower estimator and compare its performance to that of two discretizations of the flower estimator, namely the pivotal estimator......In this paper, we propose a semiautomatic procedure for estimation of particle surface area. It uses automatic segmentation of the boundaries of the particle sections and applies different estimators depending on whether the segmentation was judged by a supervising expert to be satisfactory....... If the segmentation is correct the estimate is computed automatically, otherwise the expert performs the necessary measurements manually. In case of convex particles we suggest to base the semiautomatic estimation on the so-called flower estimator, a new local stereological estimator of particle surface area...

  11. Contact area measurements on structured surfaces

    DEFF Research Database (Denmark)

    Kücükyildiz, Ömer Can; Jensen, Sebastian Hoppe Nesgaard; De Chiffre, Leonardo

    In connection with the use of brass specimens featuring structured surfaces in a tribology test, an algorithm was developed for automatic measurement of the contact area by optical means.......In connection with the use of brass specimens featuring structured surfaces in a tribology test, an algorithm was developed for automatic measurement of the contact area by optical means....

  12. Surface dependency in thermodynamics of ideal gases

    International Nuclear Information System (INIS)

    Sisman, Altug

    2004-01-01

    The Casimir-like size effect rises in ideal gases confined in a finite domain due to the wave character of atoms. By considering this effect, thermodynamic properties of an ideal gas confined in spherical and cylindrical geometries are derived and compared with those in rectangular geometry. It is seen that an ideal gas exhibits an unavoidable quantum surface free energy and surface over volume ratio becomes a control variable on thermodynamic state functions in microscale. Thermodynamics turns into non-extensive thermodynamics and geometry difference becomes a driving force since the surface over volume ratio depends on the geometry

  13. Surface moisture estimation in urban areas

    Science.gov (United States)

    Jiang, Yitong

    Surface moisture is an important parameter because it modifies urban microclimate and surface layer meteorology. The primary objectives of this paper are: 1) to analyze the impact of surface roughness from buildings on surface moisture in urban areas; and 2) to quantify the impact of surface roughness resulting from urban trees on surface moisture. To achieve the objectives, two hypotheses were tested: 1) the distribution of surface moisture is associated with the structural complexity of buildings in urban areas; and 2) The distribution and change of surface moisture is associated with the distribution and vigor of urban trees. The study area is Indianapolis, Indiana, USA. In the part of the morphology of urban trees, Warren Township was selected due to the limitation of tree inventory data. To test the hypotheses, the research design was made to extract the aerodynamic parameters, such as frontal areas, roughness length and displacement height of buildings and trees from Terrestrial and Airborne LiDAR data, then to input the aerodynamic parameters into the urban surface energy balance model. The methodology was developed for comparing the impact of aerodynamic parameters from LiDAR data with the parameters that were derived empirically from land use and land cover data. The analytical procedures are discussed below: 1) to capture the spatial and temporal variation of surface moisture, daily and hourly Land Surface Temperature (LST) were downscaled from 4 km to 1 km, and 960 m to 30 m, respectively, by regression between LST and various components that impact LST; 2) to estimate surface moisture, namely soil moisture and evapotranspiration (ET), land surfaces were classified into soil, vegetation, and impervious surfaces, using Linear Spectral Mixture Analysis (LSMA); 3) aerodynamic parameters of buildings and trees were extracted from Airborne and Terrestrial LiDAR data; 4) the Temperature-Vegetation-Index (TVX) method, and the Two-Source-Energy-Balance (TSEB

  14. Monitoring System for ALICE Surface Areas

    CERN Document Server

    Demirbasci, Oguz

    2016-01-01

    I have been at CERN for 12 weeks within the scope of Summer Student Programme working on a monitoring system project for surface areas of the ALICE experiment during this period of time. The development and implementation of a monitoring system for environmental parameters in the accessible areas where a cheap hardware setup can be deployed were aim of this project. This report explains how it was developed by using Arduino, Raspberry PI, WinCC OA and DIM protocol.

  15. Volumes and surface areas of pendular rings

    Science.gov (United States)

    Rose, W.

    1958-01-01

    A packing of spheres is taken as a suitable model of porous media. The packing may be regular and the sphere size may be uniform, but in general, both should be random. Approximations are developed to give the volumes and surface areas of pendular rings that exist at points of sphere contact. From these, the total free volume and interfacial specific surface area are derived as expressive of the textural character of the packing. It was found that the log-log plot of volumes and surface areas of pendular rings vary linearly with the angle made by the line joining the sphere centers and the line from the center of the largest sphere to the closest edge of the pendular ring. The relationship, moreover, was found not to be very sensitive to variation in the size ratio of the spheres in contact. It also was found that the addition of pendular ring material to various sphere packings results in an unexpected decrease in the surface area of the boundaries that confine the resulting pore space. ?? 1958 The American Institute of Physics.

  16. Estimating surface area in early hominins.

    Directory of Open Access Journals (Sweden)

    Alan Cross

    Full Text Available Height and weight-based methods of estimating surface area have played an important role in the development of the current consensus regarding the role of thermoregulation in human evolution. However, such methods may not be reliable when applied to early hominins because their limb proportions differ markedly from those of humans. Here, we report a study in which this possibility was evaluated by comparing surface area estimates generated with the best-known height and weight-based method to estimates generated with a method that is sensitive to proportional differences. We found that the two methods yield indistinguishable estimates when applied to taxa whose limb proportions are similar to those of humans, but significantly different results when applied to taxa whose proportions differ from those of humans. We also found that the discrepancy between the estimates generated by the two methods is almost entirely attributable to inter-taxa differences in limb proportions. One corollary of these findings is that we need to reassess hypotheses about the role of thermoregulation in human evolution that have been developed with the aid of height and weight-based methods of estimating body surface area. Another is that we need to use other methods in future work on fossil hominin body surface areas.

  17. Osmosis and Surface Area to Volume Ratio.

    Science.gov (United States)

    Barrett, D. R. B.

    1984-01-01

    Describes an experiment designed to help students understand the concepts of osmosis and surface area to volume ratio (SA:VOL). The task for students is to compare water uptake in different sizes of potato cubes and relate differences to their SA:VOL ratios. (JN)

  18. Characterization of high surface area silicon oxynitrides

    International Nuclear Information System (INIS)

    Lednor, P.W.; DeRuiter, R.; Emeis, K.A.

    1992-01-01

    In heterogenous catalysis, liquid or gaseous feedstocks are converted over a solid catalyst into more desirable products. Such processes form an essential part of the oil and petrochemical industries. The solid catalyst usually consists of an inorganic phase, with or without metal particles on the surface. Examples include platinum particles on gamma alumina (a reforming catalyst used in oil processing), chromium particles on silica (an ethylene polymerization catalyst) and zeolites or amorphous silica-aluminas (used as solid acids).Oxides have been widely investigated in catalysis, and silica, alumina, and aluminosilicates find application commercially on a large scale. On the other hand, non-oxide materials such as nitrides, carbides and borides have been relatively little investigated. The main reason for this has been the lack of routes to the high surface area forms usually required in catalysis. However, this situation has changed significantly in recent years, due to the interest in high surface area non-oxides as precursors to fully dense ceramics; in this paper, the authors have reviewed synthetic routes to high surface area non-oxides

  19. High Surface Area Tunnels in Hexagonal WO₃.

    Science.gov (United States)

    Sun, Wanmei; Yeung, Michael T; Lech, Andrew T; Lin, Cheng-Wei; Lee, Chain; Li, Tianqi; Duan, Xiangfeng; Zhou, Jun; Kaner, Richard B

    2015-07-08

    High surface area in h-WO3 has been verified from the intracrystalline tunnels. This bottom-up approach differs from conventional templating-type methods. The 3.67 Å diameter tunnels are characterized by low-pressure CO2 adsorption isotherms with nonlocal density functional theory fitting, transmission electron microscopy, and thermal gravimetric analysis. These open and rigid tunnels absorb H(+) and Li(+), but not Na(+) in aqueous electrolytes without inducing a phase transformation, accessing both internal and external active sites. Moreover, these tunnel structures demonstrate high specific pseudocapacitance and good stability in an H2SO4 aqueous electrolyte. Thus, the high surface area created from 3.67 Å diameter tunnels in h-WO3 shows potential applications in electrochemical energy storage, selective ion transfer, and selective gas adsorption.

  20. Estimation of surface area and surface area measure of three-dimensional sets from digitizations

    DEFF Research Database (Denmark)

    Ziegel, Johanna; Kiderlen, Markus

    2010-01-01

    A local method for estimating surface area and surface area measure of three-dimensional objects from discrete binary images is presented. A weight is assigned to each 2 × 2 × 2 configuration of voxels and the total surface area of an object is given by summation of the local area contributions....... The method is based on an exact asymptotic result that holds for increasing resolution of the digitization. It states that the number of occurrences of a 2 ×  2 × 2 configuration is asymptotically proportional to an integral of its “h-function” with respect to the surface area measure of the object. We find...

  1. High surface area fibrous silica nanoparticles

    KAUST Repository

    Polshettiwar, Vivek

    2014-11-11

    Disclosed are high surface area nanoparticles that have a fibrous morphology. The nanoparticles have a plurality of fibers, wherein each fiber is in contact with one other fiber and each fiber has a length of between about 1 nm and about 5000 nm. Also disclosed are applications of the nanoparticles of the present invention, and methods of fabrication of the nanoparticles of the present invention.

  2. Estimating the surface area of birds: using the homing pigeon (Columba livia as a model

    Directory of Open Access Journals (Sweden)

    Cristina R. Perez

    2014-05-01

    Full Text Available Estimation of the surface area of the avian body is valuable for thermoregulation and metabolism studies as well as for assessing exposure to oil and other surface-active organic pollutants from a spill. The use of frozen carcasses for surface area estimations prevents the ability to modify the posture of the bird. The surface area of six live homing pigeons in the fully extended flight position was estimated using a noninvasive method. An equation was derived to estimate the total surface area of a pigeon based on its body weight. A pigeon's surface area in the fully extended flight position is approximately 4 times larger than the surface area of a pigeon in the perching position. The surface area of a bird is dependent on its physical position, and, therefore, the fully extended flight position exhibits the maximum area of a bird and should be considered the true surface area of a bird.

  3. A Simple Proof of Cauchy's Surface Area Formula

    OpenAIRE

    Tsukerman, Emmanuel; Veomett, Ellen

    2016-01-01

    We give a short and simple proof of Cauchy's surface area formula, which states that the average area of a projection of a convex body is equal to its surface area up to a multiplicative constant in the dimension.

  4. Clay mineralogy in different geomorphic surfaces in sugarcane areas

    Science.gov (United States)

    Camargo, L.; Marques, J., Jr.

    2012-04-01

    The crystallization of the oxides and hydroxides of iron and aluminum and kaolinite of clay fraction is the result of pedogenetic processes controlled by the relief. These minerals have influence on the physical and chemical attributes of soil and exhibit spatial dependence. The pattern of spatial distribution is influenced by forms of relief as the geomorphic surfaces. In this sense, the studies aimed at understanding the relationship between relief and the distribution pattern of the clay fraction attributes contribute to the delineation of specific areas of management in the field. The objective of this study was to evaluate the spatial distribution of oxides and hydroxides of iron and aluminum and kaolinite of clay fraction and its relationship with the physical and chemical attributes in different geomorphic surfaces. Soil samples were collected in a transect each 25 m (100 samples) and in the sides of the same (200 samples) as well as an area of 500 ha (1 sample each six hectare). Geomorphic surfaces (GS) in the transect were mapped in detail to support mapping the entire area. The soil samples were taken to the laboratory for chemical, physical, and mineralogical analysis, and the pattern of spatial distribution of soil attributes was obtained by statistics and geostatistics. The GS I is considered the oldest surface of the study area, with depositional character, and a slope ranging from 0 to 4%. GS II and III are considered to be eroded, and the surface II plan a gentle slope that extends from the edge of the surface until the beginning of I and III. The crystallographic characteristics of the oxides and hydroxides of iron and aluminum and kaolinite showed spatial dependence and the distribution pattern corresponding to the limits present of the GS in the field. Surfaces I and II showed the best environments to the degree of crystallinity of hematite and the surface III to the greatest degree of crystallinity of goethite agreeing to the pedoenvironment

  5. Surface conductivity dependent dynamic behaviour of an ultrafine atmospheric pressure plasma jet for microscale surface processing

    Energy Technology Data Exchange (ETDEWEB)

    Abuzairi, Tomy [Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8561 (Japan); Department of Electrical Engineering, Faculty of Engineering, Universitas Indonesia, Depok 16424 (Indonesia); Okada, Mitsuru [Department of Engineering, Shizuoka University, Hamamatsu 432-8561 (Japan); Bhattacharjee, Sudeep [Department of Physics, Indian Institute of Technology, Kanpur 208016 (India); Nagatsu, Masaaki, E-mail: nagatsu.masaaki@shizuoka.ac.jp [Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8561 (Japan); Department of Engineering, Shizuoka University, Hamamatsu 432-8561 (Japan); Research Institute of Electronics, Shizuoka University, Hamamatsu 432-8561 (Japan)

    2016-12-30

    Highlights: • Spatio-temporal behaviors of capillary APPJs are studied for various substrates. • Plasma irradiation area depended on the substrate conductivity and permittivity. • Surface irradiation area was significantly broadened in polymer-like substrate. • Effect of applying a substrate bias on the APPJ irradiation area was investigated. - Abstract: An experimental study on the dynamic behaviour of microcapillary atmospheric pressure plasma jets (APPJs) with 5 μm tip size for surfaces of different conductivity is reported. Electrical and spatio-temporal characteristics of the APPJs are monitored using high voltage probe, current monitor and high speed intensified charge couple device camera. From these experimental results, we presented a simple model to understand the electrical discharge characteristics of the capillary APPJs with double electrodes, and estimated the velocity of the ionization fronts in the jet and the electron density to be 3.5–4.2 km/s and 2–7 × 10{sup 17} m{sup −3}. By analyzing the dynamics of the microcapillary APPJs for different substrate materials, it was found that the surface irradiation area strongly depended on the substrate conductivity and permittivity, especially in the case of polymer-like substrate, surface irradiation area was significantly broadened probably due to the repelling behaviour of the plasma jets from the accumulated electrical charges on the polymer surface. The effect of applying a substrate bias in the range from −900 V to +900 V on the plasma irradiation onto the substrates was also investigated. From the knowledge of the present results, it is helpful for choosing the substrate materials for microscale surface modification.

  6. Method for treatment of a surface area of steel

    NARCIS (Netherlands)

    Bhowmik, S.; Aaldert, P.J.

    2009-01-01

    The invention relates to a method for treatment of a surface area of steel by polishing said surface area and performing a plasma treatment of said surface area wherein the plasma treatment is performed at at least atmospheric conditions and wherein the plasma treatment is carried out at a power of

  7. Molecularly-Limited Fractal Surface Area of Mineral Powders

    Directory of Open Access Journals (Sweden)

    Petr Jandacka

    2016-05-01

    Full Text Available The topic of the specific surface area (SSA of powders is not sufficiently described in the literature in spite of its nontrivial contribution to adsorption and dissolution processes. Fractal geometry provides a way to determine this parameter via relation SSA ~ x(D − 3s(2 − D, where x (m is the particle size and s (m is a scale. Such a relation respects nano-, micro-, or macro-topography on the surface. Within this theory, the fractal dimension 2 ≤ D < 3 and scale parameter s plays a significant role. The parameter D may be determined from BET or dissolution measurements on several samples, changing the powder particle sizes or sizes of adsorbate molecules. If the fractality of the surface is high, the SSA does not depend on the particle size distribution and vice versa. In this paper, the SSA parameter is analyzed from the point of view of adsorption and dissolution processes. In the case of adsorption, a new equation for the SSA, depending on the term (2 − D∙(s2 − sBET/sBET, is derived, where sBET and s2 are effective cross-sectional diameters for BET and new adsorbates. Determination of the SSA for the dissolution process appears to be very complicated, since the fractality of the surface may change in the process. Nevertheless, the presented equations have good application potential.

  8. Surface areas of fractally rough particles studied by scattering

    International Nuclear Information System (INIS)

    Hurd, A.J.; Schaefer, D.W.; Smith, D.M.; Ross, S.B.; Le Mehaute, A.; Spooner, S.

    1989-01-01

    The small-angle scattering from fractally rough surfaces has the potential to give information on the surface area at a given resolution. By use of quantitative neutron and x-ray scattering, a direct comparison of surface areas of fractally rough powders was made between scattering and adsorption techniques. This study supports a recently proposed correction to the theory for scattering from fractal surfaces. In addition, the scattering data provide an independent calibration of molecular adsorbate areas

  9. Properties that influence the specific surface areas of carbon nanotubes and nanofibers.

    Science.gov (United States)

    Birch, M Eileen; Ruda-Eberenz, Toni A; Chai, Ming; Andrews, Ronnee; Hatfield, Randal L

    2013-11-01

    Commercially available carbon nanotubes and nanofibers were analyzed to examine possible relationships between their Brunauer-Emmett-Teller specific surface areas (SSAs) and their physical and chemical properties. Properties found to influence surface area were number of walls/diameter, impurities, and surface functionalization with hydroxyl and carboxyl groups. Characterization by electron microscopy, energy-dispersive X-ray spectrometry, thermogravimetric analysis, and elemental analysis indicates that SSA can provide insight on carbon nanomaterials properties, which can differ vastly depending on synthesis parameters and post-production treatments. In this study, how different properties may influence surface area is discussed. The materials examined have a wide range of surface areas. The measured surface areas differed from product specifications, to varying degrees, and between similar products. Findings emphasize the multiple factors that influence surface area and mark its utility in carbon nanomaterial characterization, a prerequisite to understanding their potential applications and toxicities. Implications for occupational monitoring are discussed.

  10. Error bounds for surface area estimators based on Crofton's formula

    DEFF Research Database (Denmark)

    Kiderlen, Markus; Meschenmoser, Daniel

    2009-01-01

    According to Crofton’s formula, the surface area S(A) of a sufficiently regular compact set A in R^d is proportional to the mean of all total projections pA (u) on a linear hyperplane with normal u, uniformly averaged over all unit vectors u. In applications, pA (u) is only measured in k directio...... in the sense that the relative error of the surface area estimator is very close to the minimal error....... and the mean is approximated by a finite weighted sum S(A) of the total projections in these directions. The choice of the weights depends on the selected quadrature rule. We define an associated zonotope Z (depending only on the projection directions and the quadrature rule), and show that the relative error...... S (A)/S (A) is bounded from below by the inradius of Z and from above by the circumradius of Z. Applying a strengthened isoperimetric inequality due to Bonnesen, we show that the rectangular quadrature rule does not give the best possible error bounds for d = 2. In addition, we derive asymptotic...

  11. Nondestructive, stereological estimation of canopy surface area

    DEFF Research Database (Denmark)

    Wulfsohn, Dvora-Laio; Sciortino, Marco; Aaslyng, Jesper M.

    2010-01-01

    a canopy using the smooth fractionator, (ii) sampling of leaves from the selected plants using the fractionator, and (iii) area estimation of the sampled leaves using point counting. We apply this procedure to estimate the total area of a chrysanthemum (Chrysanthemum morifolium L.) canopy and evaluate both...

  12. Surface texturing of crystalline silicon and effective area measurement

    Science.gov (United States)

    Sun, Tietun; Chen, Dong; Chui, Rongqiang

    2000-11-01

    In this paper, the surface area of solar cell is determined by the capacitance measurements of MOS structure. The texture etching technology can be controlled according to the change of silicon surface area, furthermore, the textured silicon surface and interface characteristic of solar cell can be studied by measuring the relationship of capacitance and voltage for MOS structure.

  13. THE DEPENDENCE OF STAR FORMATION EFFICIENCY ON GAS SURFACE DENSITY

    International Nuclear Information System (INIS)

    Burkert, Andreas; Hartmann, Lee

    2013-01-01

    Studies by Lada et al. and Heiderman et al. have suggested that star formation mostly occurs above a threshold in gas surface density Σ of Σ c ∼ 120 M ☉ pc –2 (A K ∼ 0.8). Heiderman et al. infer a threshold by combining low-mass star-forming regions, which show a steep increase in the star formation rate per unit area Σ SFR with increasing Σ, and massive cores forming luminous stars which show a linear relation. We argue that these observations do not require a particular density threshold. The steep dependence of Σ SFR , approaching unity at protostellar core densities, is a natural result of the increasing importance of self-gravity at high densities along with the corresponding decrease in evolutionary timescales. The linear behavior of Σ SFR versus Σ in massive cores is consistent with probing dense gas in gravitational collapse, forming stars at a characteristic free-fall timescale given by the use of a particular molecular tracer. The low-mass and high-mass regions show different correlations between gas surface density and the area A spanned at that density, with A ∼ Σ –3 for low-mass regions and A ∼ Σ –1 for the massive cores; this difference, along with the use of differing techniques to measure gas surface density and star formation, suggests that connecting the low-mass regions with massive cores is problematic. We show that the approximately linear relationship between dense gas mass and stellar mass used by Lada et al. similarly does not demand a particular threshold for star formation and requires continuing formation of dense gas. Our results are consistent with molecular clouds forming by galactic hydrodynamic flows with subsequent gravitational collapse

  14. Hand surface area as a percentage of body surface area in Asian children: a pilot study.

    Science.gov (United States)

    Choi, Hyuk; Park, Man Sik; Lee, Heung-Man

    2011-09-01

    The hand surface area (HSA) of one hand has been estimated as 1% of the body surface area (BSA). This does change with the patient's age, gender, and body mass index (BMI). There are many HSA studies done on adult populations, but fewer done on children. Our hypothesis in this study is that the general HSA equation for Caucasian adults cannot be applied as accurately to children and Asian people. HSA was defined as the area of the palm without fingers in this study. Children are in a stage of growth. If a child's hand growth ratio is not the same as that of an adult, the result of HSA/BSA calculation could be different. We undertook this study to determine whether or not there were any differences in HSA/BSA among Korean children (7-18 years) and adults (20-60 years), and compared our results with western data. A total of 186 boys aged between 7 and 18 years, were recruited for this study; their HSA was measured, directly. A total of 186 adults aged between 20 and 60 years were selected as well. BSA was calculated only for volunteers in subjects who HSA had been measured. From these results, HSA/BSA was calculated. HSA/BSA ratio of Korean boys was 0.69±0.05%, which was less than 1%. It is suggested that the ratio of the western data may not be applicable to Asian children, particularly, Korean children. HSA/BSA ratio can be applied in administration of drug doses and estimation of the area of burns. Copyright © 2011 Elsevier Ltd and ISBI. All rights reserved.

  15. SurfaceWater Source Protection Areas (SPAs)

    Data.gov (United States)

    Vermont Center for Geographic Information — Source Protection Area (SPA) boundaries have been located on RF 24000 & RF 25000 scale USGS topographic maps by Water Supply Division (DEC) and VT Dept of Health...

  16. How surface roughness affects the angular dependence of the sputtering yield

    International Nuclear Information System (INIS)

    Hu, A.; Hassanein, A.

    2012-01-01

    Comprehensive model is developed to study the impact of surface roughness on the angular dependence of sputtering yield. Instead of assuming surfaces to be flat or composed of exact self-similar fractals, we developed a new method to describe the surfaces. Random fractal surfaces generated by midpoint displacement algorithm in computer graphics area and Support vector machine algorithm in pattern recognition area are combined with the Monte Carlo ion bombardment simulation code, i.e., Ion Transport in Materials and Compounds (ITMC) code . With this new fractal version of ITMC-F, we successfully simulated the angular dependence of sputtering yield for various ion-target combinations. Examples are given for 5 keV Ar ions bombarding iron, graphite, and silicon surfaces, with the input surface roughness exponent directly depicted from experimental data. Comparison is made with previous models to account for surface roughness and recent experimental data. The ITMC-F code showed good agreement with the experimental data.

  17. The Surface Chemical Properties of Novel High Surface Area Solids ...

    African Journals Online (AJOL)

    during zeolite synthesis.22 Because raw fly ash has large quanti- ties of a host of elements, many of these will act as nucleation sites, which results in many small crystals rather than a few large ones. Acid etching removed the needle-like structures on the particle surfaces, revealing a porous underlying structure. (Fig. 1c).

  18. Formation of biocompatible surface layers depending on the sputtering distance

    Science.gov (United States)

    Nasakina, E. O.; Seregin, A. V.; Baikin, A. S.; Kaplan, M. A.; Konushkin, S. V.; Sergiyenko, K. V.; Kovaleva, E. D.; Kolmakova, A. A.; Leonov, A. V.; Sevost'yanov, M. A.; Kolmakov, A. G.; Simakov, S. V.

    2017-05-01

    Nano- and micro-dimensional surface layers of silver and tantalum on flat and wire NiTi substrates by the method of magnetron sputtering in vacuum were produced. The structure and composition of the samples were determined using SEM and Auger spectroscopy. With an increase in the sputtering distance, the thickness of the surface layers decreases, and the thickness of the transition layer and the dependence of the thickness change as a whole depend on the nature of the sputtered substance.

  19. Surface Area Distribution Descriptor for object matching

    Directory of Open Access Journals (Sweden)

    Mohamed F. Gafar

    2010-07-01

    Full Text Available Matching 3D objects by their similarity is a fundamental problem in computer vision, computer graphics and many other fields. The main challenge in object matching is to find a suitable shape representation that can be used to accurately and quickly discriminate between similar and dissimilar shapes. In this paper we present a new volumetric descriptor to represent 3D objects. The proposed descriptor is used to match objects under rigid transformations including uniform scaling. The descriptor represents the object by dividing it into shells, acquiring the area distribution of the object through those shells. The computed areas are normalised to make the descriptor scale-invariant in addition to rotation and translation invariant. The effectiveness and stability of the proposed descriptor to noise and variant sampling density as well as the effectiveness of the similarity measures are analysed and demonstrated through experimental results.

  20. Inevitable surface dependence of some operator products and integrability

    International Nuclear Information System (INIS)

    Shigemoto, Kazuyasu; Tanaka, Azuma; Taguchi, Yukio; Yamamoto, Kunio.

    1976-01-01

    In general even in local theory the operator products at the same space-time point must be considered as a limit of non-local products. It is natural to confine non-locality on a space-like surface. In this case some operator products with three or more constituents possess an inevitable and purely quantum-mechanical surface dependence. Taking the pion-nucleon system as an example, we explicitly calculate in the order of g 2 this kind of the surface dependence of the interaction Hamiltonian. In order to obtain a consistent theory, this surface is required to be identified with the space-like surface in the Tomonaga-Schwinger equation. Then the interaction Hamiltonian needs an additional, non-canonical and surface-dependent term, which can be derived uniquely from the canonical Hamiltonian. The integrability of the Tomonaga-Schwinger equation is proved by taking account of this surface dependence together with the gradient term in the equal-time commutator. (auth.)

  1. Why Do We Need the Derivative for the Surface Area?

    Science.gov (United States)

    Hristova, Yulia; Zeytuncu, Yunus E.

    2016-01-01

    Surface area and volume computations are the most common applications of integration in calculus books. When computing the surface area of a solid of revolution, students are usually told to use the frustum method instead of the disc method; however, a rigorous explanation is rarely provided. In this note, we provide one by using geometric…

  2. Dynamic characterisation of the specific surface area for fracture networks

    Science.gov (United States)

    Cvetkovic, V.

    2017-12-01

    One important application of chemical transport is geological disposal of high-level nuclear waste for which crystalline rock is a prime candidate for instance in Scandinavia. Interconnected heterogeneous fractures of sparsely fractured rock such as granite, act as conduits for transport of dissolved tracers. Fluid flow is known to be highly channelized in such rocks. Channels imply narrow flow paths, adjacent to essentially stagnant water in the fracture and/or the rock matrix. Tracers are transported along channelised flow paths and retained by minerals and/or stagnant water, depending on their sorption properties; this mechanism is critical for rocks to act as a barrier and ultimately provide safety for a geological repository. The sorbing tracers are retained by diffusion and sorption on mineral surfaces, whereas non-sorbing tracers can be retained only by diffusion into stagnant water of fractures. The retention and transport properties of a sparsely fractured rock will primarily depend on the specific surface area (SSA) of the fracture network which is determined by the heterogeneous structure and flow. The main challenge when characterising SSA on the field-scale is its dependence on the flow dynamics. We first define SSA as a physical quantity and clarify its importance for chemical transport. A methodology for dynamic characterisation of SSA in fracture networks is proposed that relies on three sets of data: i) Flow rate data as obtained by a flow logging procedure; ii) transmissivity data as obtained by pumping tests; iii) fracture network data as obtained from outcrop and geophysical observations. The proposed methodology utilises these data directly as well as indirectly through flow and particle tracking simulations in three-dimensional discrete fracture networks. The methodology is exemplified using specific data from the Swedish site Laxemar. The potential impact of uncertainties is of particular significance and is illustrated for radionuclide

  3. Estimating the surface area of birds: using the homing pigeon (Columba livia) as a model.

    Science.gov (United States)

    Perez, Cristina R; Moye, John K; Pritsos, Chris A

    2014-05-08

    Estimation of the surface area of the avian body is valuable for thermoregulation and metabolism studies as well as for assessing exposure to oil and other surface-active organic pollutants from a spill. The use of frozen carcasses for surface area estimations prevents the ability to modify the posture of the bird. The surface area of six live homing pigeons in the fully extended flight position was estimated using a noninvasive method. An equation was derived to estimate the total surface area of a pigeon based on its body weight. A pigeon's surface area in the fully extended flight position is approximately 4 times larger than the surface area of a pigeon in the perching position. The surface area of a bird is dependent on its physical position, and, therefore, the fully extended flight position exhibits the maximum area of a bird and should be considered the true surface area of a bird. © 2014. Published by The Company of Biologists Ltd | Biology Open.

  4. Comparison of diffusion charging and mobility-based methods for measurement of aerosol agglomerate surface area.

    Science.gov (United States)

    Ku, Bon Ki; Kulkarni, Pramod

    2012-05-01

    We compare different approaches to measure surface area of aerosol agglomerates. The objective was to compare field methods, such as mobility and diffusion charging based approaches, with laboratory approach, such as Brunauer, Emmett, Teller (BET) method used for bulk powder samples. To allow intercomparison of various surface area measurements, we defined 'geometric surface area' of agglomerates (assuming agglomerates are made up of ideal spheres), and compared various surface area measurements to the geometric surface area. Four different approaches for measuring surface area of agglomerate particles in the size range of 60-350 nm were compared using (i) diffusion charging-based sensors from three different manufacturers, (ii) mobility diameter of an agglomerate, (iii) mobility diameter of an agglomerate assuming a linear chain morphology with uniform primary particle size, and (iv) surface area estimation based on tandem mobility-mass measurement and microscopy. Our results indicate that the tandem mobility-mass measurement, which can be applied directly to airborne particles unlike the BET method, agrees well with the BET method. It was also shown that the three diffusion charging-based surface area measurements of silver agglomerates were similar within a factor of 2 and were lower than those obtained from the tandem mobility-mass and microscopy method by a factor of 3-10 in the size range studied. Surface area estimated using the mobility diameter depended on the structure or morphology of the agglomerate with significant underestimation at high fractal dimensions approaching 3.

  5. Lage-area planar RF plasma productions by surface waves

    International Nuclear Information System (INIS)

    Nonaka, S.

    1994-01-01

    Large-area rf plasmas are confirmed to be produced by means of RF discharges inside a large-area dielectric tube. The plasma space is 73 cm x 176 cm and 2.5 cm. The plasma is thought to be produced by an odd plasma-surface wave (PSW ο ) in case of using large-area electrodes and by an even plasma-surface wave (PSW ο ) in case of without the electrodes. (author). 7 refs, 4 figs

  6. Bulk Heterojunction Organic Solar Cell Area-Dependent Parameter Fluctuation

    Directory of Open Access Journals (Sweden)

    A. J. Trindade

    2017-01-01

    Full Text Available Organic solar cell efficiency is known to be active area dependent and is usually a problem in the upscale factor for market applications. In this work, a detailed study of organic photovoltaic devices with active layer based on poly(3-hexylthiophene (P3HT and 1-(3-methoxycarbonyl-propyl-1-phenyl-(6,6C61 (PCBM is made, evaluating the effect of the change on the active area from 10−2 to 4 cm4. The device structure was kept simple in order to allow the understanding of the physical effects involved. Device figures of merit were extracted from the equivalent circuit using a genetic-based algorithm, and their relationship with the active area was compared. It is observed that the efficiency drops significantly with the active area increase (as the fill factor while the parallel and series resistance, adjusted to the active area, seems to be relatively constant and increases linearly, respectively. The short circuit current and the generated photocurrent also drop significantly with the active area increase. The open circuit voltage does not show major changes. These results are discussed considering the main influences for the observed efficiency data. Particularly, as the basic circuit model seems to fail to explain the macroscopic results, the behavior can be related with the enlargement of defect interaction.

  7. Measurement of the specific surface area of loose copper deposit by electrochemical methods

    Directory of Open Access Journals (Sweden)

    E. A. Dolmatova

    2016-07-01

    Full Text Available In the work the surface area of the electrode with dispersed copper deposit obtained within 30 seconds was evaluated by techniques of chronopotentiometry (CPM and impedance spectroscopy. In method CPM the electrode surface available for measurement depends on the value of the polarizing current. At high currents during the transition time there is a change of surface relief that can not determine the full surface of loose deposit. The electrochemical impedance method is devoid of this shortcoming since the measurements are carried out in indifferent electrolyte in the absence of current. The area measured by the impedance is tens of times higher than the value obtained by chronopotentiometry. It is found that from a solution containing sulfuric acid the deposits form with a high specific surface area. Based on these data it was concluded that the method of impedance spectroscopy can be used to measure in situ the surface area of the dispersed copper deposits.

  8. Indexing aortic valve area by body surface area increases the prevalence of severe aortic stenosis

    DEFF Research Database (Denmark)

    Jander, Nikolaus; Gohlke-Bärwolf, Christa; Bahlmann, Edda

    2014-01-01

    To account for differences in body size in patients with aortic stenosis, aortic valve area (AVA) is divided by body surface area (BSA) to calculate indexed AVA (AVAindex). Cut-off values for severe stenosis are......To account for differences in body size in patients with aortic stenosis, aortic valve area (AVA) is divided by body surface area (BSA) to calculate indexed AVA (AVAindex). Cut-off values for severe stenosis are...

  9. Inelastic surface vibrations versus energy-dependent nucleus ...

    Indian Academy of Sciences (India)

    Abstract. Limitations of the static Woods–Saxon potential and the applicability of the energy- dependent Woods–Saxon potential (EDWSP) model within the framework of one-dimensional. Wong formula to explore the sub-barrier fusion data are highlighted. The inelastic surface exci- tations of the fusing nuclei are found to ...

  10. Inelastic surface vibrations versus energy-dependent nucleus ...

    Indian Academy of Sciences (India)

    Limitations of the static Woods–Saxon potential and the applicability of the energy dependent Woods–Saxon potential (EDWSP) model within the framework of one-dimensional Wong formula to explore the sub-barrier fusion data are highlighted. The inelastic surface excitations of the fusing nuclei are found to be ...

  11. Effect of impervious surface area and vegetation changes on mean ...

    African Journals Online (AJOL)

    This land use or land cover changes are also thought to affect the climate of the Tshwane metropolis as is evidenced by heat waves in 2013 and 2014. This paper describes how vegetation and impervious surface area (ISA) or built up areas were classified from Landsat 8 LCDM, 2013, and Landsat 7 ETM+, 2003 images ...

  12. Rough surface electrical contact resistance considering scale dependent properties and quantum effects

    International Nuclear Information System (INIS)

    Jackson, Robert L.; Crandall, Erika R.; Bozack, Michael J.

    2015-01-01

    The objective of this work is to evaluate the effect of scale dependent mechanical and electrical properties on electrical contact resistance (ECR) between rough surfaces. This work attempts to build on existing ECR models that neglect potentially important quantum- and size-dependent contact and electrical conduction mechanisms present due to the asperity sizes on typical surfaces. The electrical conductance at small scales can quantize or show a stepping trend as the contact area is varied in the range of the free electron Fermi wavelength squared. This work then evaluates if these effects remain important for the interface between rough surfaces, which may include many small scale contacts of varying sizes. The results suggest that these effects may be significant in some cases, while insignificant for others. It depends on the load and the multiscale structure of the surface roughness

  13. Surface area considerations for corroding N reactor fuel

    International Nuclear Information System (INIS)

    Johnson, A.B. Jr.; Pitner, A.L.

    1996-06-01

    The N Reactor fuel is corroding at sites where the Zircaloy cladding was damaged when the fuel was discharged from the reactor. Corroding areas are clearly visible on the fuel stored in open cans in the K East Basin. There is a need to estimate the area of the corroding uranium to analyze aspects of fuel behavior as it is transitioned. from current wet storage to dry storage. In this report, the factors that contribute to open-quotes trueclose quotes surface area are analyzed in terms of what is currently known about the N Reactor fuel. Using observations from a visual examinations of the fuel in the K East wet storage facility, a value for the corroding geometric area is estimated. Based on observations of corroding uranium and surface roughness values for other metals, a surface roughness factor is also estimated and applied to the corroding K East fuel to provide an estimated open-quotes trueclose quotes surface area. While the estimated area may be modified as additional data become available from fuel characterization studies, the estimate provides a basis to assess effects of exposed uranium metal surfaces on fuel behavior in operations involved in transitioning from wet to dry storage, during shipment and staging, conditioning, and dry interim storage

  14. Assessment of dialyzer surface in online hemodiafiltration; objective choice of dialyzer surface area

    Directory of Open Access Journals (Sweden)

    Francisco Maduell

    2015-05-01

    Conclusion: The increase in 40% and 80% of dialyzer surface area entails an increase in convective volume of 6 and 16% respectively, showing minimal differences both in convective volume and clearance capacity when UFC was greater than 45 mL/h/mmHg. It is advisable to optimise dialyser efficiency to the smallest surface area possible, adjusting treatment prescription.

  15. Students' and Teachers' Application of Surface Area to Volume Relationships

    Science.gov (United States)

    Taylor, Amy R.; Jones, M. Gail

    2013-02-01

    The National Science Education Standards emphasize teaching unifying concepts and processes such as basic functions of living organisms, the living environment, and scale (NRC 2011). Scale includes understanding that different characteristics, properties, or relationships within a system might change as its dimensions are increased or decreased (NRC 2011). One such relationship involves surface area to volume which is a pervasive concept that can be found throughout different sciences. This concept is important for students to not only understand the association of the two, but to also be able to apply this relationship in science contexts. The purpose of this study is to investigate the factors that influence the understanding surface area to volume relationships. This study examined middle school students', high school students', and science teachers' logical thinking skills (including proportional reasoning), visual-spatial skills, and understandings of surface area to volume relationships. Regression results indicated that participants' reasoning abilities and components of visual-spatial skills could be possible predictors for one's ability to understand surface area to volume relationships. Implications for teaching scale concepts such as surface area to volume relationships in the science classroom are discussed.

  16. Surface deformation of the secondary former mining areas

    Directory of Open Access Journals (Sweden)

    Tadeusz Głowacki

    2013-09-01

    Full Text Available The paper discuss the problem of secondary deformation observed on the surface of the land in the area of the old, non-existent copper and coal mines. The authors discuss the formation of the deformation in the final period of the mine, and after his arrest, after the close of any work of protecting the surface area of influence of mining activities. Discusses the reduction of the surface of the example of two disused mines: mining copper “Konrad” in Iwiny and “Thorez” in Walbrzych, an old coal mine. In the first part of the paper discusses a brief history of the creation of old copper basin and the Lower Silesian coal basin. It then discusses the formation of deformation processes in mining areas. Conducting continuous surveying allows you to monitor changes in the formation of land, in the paper indicate the source of the vertical displacements after ending of operation, the closure of the mine and stopped all work safety. In the area of Lower Silesia there are many remnants of disused mines, surface geodetic measurements show a constant activity in post-mining areas and the need to control the formation of the surface.

  17. Can foot anthropometric measurements predict dynamic plantar surface contact area?

    Directory of Open Access Journals (Sweden)

    Collins Natalie

    2009-10-01

    Full Text Available Abstract Background Previous studies have suggested that increased plantar surface area, associated with pes planus, is a risk factor for the development of lower extremity overuse injuries. The intent of this study was to determine if a single or combination of foot anthropometric measures could be used to predict plantar surface area. Methods Six foot measurements were collected on 155 subjects (97 females, 58 males, mean age 24.5 ± 3.5 years. The measurements as well as one ratio were entered into a stepwise regression analysis to determine the optimal set of measurements associated with total plantar contact area either including or excluding the toe region. The predicted values were used to calculate plantar surface area and were compared to the actual values obtained dynamically using a pressure sensor platform. Results A three variable model was found to describe the relationship between the foot measures/ratio and total plantar contact area (R2 = 0.77, p R2 = 0.76, p Conclusion The results of this study indicate that the clinician can use a combination of simple, reliable, and time efficient foot anthropometric measurements to explain over 75% of the plantar surface contact area, either including or excluding the toe region.

  18. High surface area electrode for high efficient microbial electrosynthesis

    Science.gov (United States)

    Nie, Huarong; Cui, Mengmeng; Lu, Haiyun; Zhang, Tian; Russell, Thomas; Lovley, Derek

    2012-02-01

    Microbial electrosynthesis, a process in which microorganisms directly accept electrons from an electrode to convert carbon dioxide and water into multi carbon organic compounds, affords a novel route for the generation of valuable products from electricity or even wastewater. The surface area of the electrode is critical for high production. A biocompatible, highly conductive, three-dimensional cathode was fabricated from a carbon nanotube textile composite to support the microorganism to produce acetate from carbon dioxide. The high surface area and macroscale porous structure of the intertwined CNT coated textile ?bers provides easy microbe access. The production of acetate using this cathode is 5 fold larger than that using a planar graphite electrode with the same volume. Nickel-nanowire-modified carbon electrodes, fabricated by microwave welding, increased the surface area greatly, were able to absorb more bacteria and showed a 1.5 fold increase in performance

  19. Particle surface area and bacterial activity in recirculating aquaculture systems

    DEFF Research Database (Denmark)

    Pedersen, Per Bovbjerg; von Ahnen, Mathis; Fernandes, Paulo

    2017-01-01

    Suspended particles in recirculating aquaculture systems (RAS) provide surface area that can be colonized by bacteria. More particles accumulate as the intensity of recirculation increases thus potentially increasing the bacterial carrying capacity of the systems. Applying a recent, rapid, cultur...... for determining bacterial activity might provide a means for future monitoring and assessment of microbial water quality in aquaculture farming systems......Suspended particles in recirculating aquaculture systems (RAS) provide surface area that can be colonized by bacteria. More particles accumulate as the intensity of recirculation increases thus potentially increasing the bacterial carrying capacity of the systems. Applying a recent, rapid, culture......-independent fluorometric detection method (Bactiquant®) for measuring bacterial activity, the current study explored the relationship between total particle surface area (TSA, derived from the size distribution of particles >5 μm) and bacterial activity in freshwater RAS operated at increasing intensity of recirculation...

  20. OBSERVED ASTEROID SURFACE AREA IN THE THERMAL INFRARED

    Energy Technology Data Exchange (ETDEWEB)

    Nugent, C. R. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Mainzer, A.; Masiero, J.; Bauer, J.; Kramer, E.; Sonnett, S. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Wright, E. L. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Grav, T. [Planetary Science Institute, Tucson, AZ (United States)

    2017-02-01

    The rapid accumulation of thermal infrared observations and shape models of asteroids has led to increased interest in thermophysical modeling. Most of these infrared observations are unresolved. We consider what fraction of an asteroid’s surface area contributes the bulk of the emitted thermal flux for two model asteroids of different shapes over a range of thermal parameters. The resulting observed surface in the infrared is generally more fragmented than the area observed in visible wavelengths, indicating high sensitivity to shape. For objects with low values of the thermal parameter, small fractions of the surface contribute the majority of thermally emitted flux. Calculating observed areas could enable the production of spatially resolved thermal inertia maps from non-resolved observations of asteroids.

  1. STEREOLOGICAL ESTIMATION OF SURFACE AREA FROM DIGITAL IMAGES

    Directory of Open Access Journals (Sweden)

    Johanna Ziegel

    2011-05-01

    Full Text Available A sampling design of local stereology is combined with a method from digital stereology to yield a novel estimator of surface area based on counts of configurations observed in a digitization of an isotropic 2- dimensional slice with thickness s. As a tool, a result of the second author and J. Rataj on infinitesimal increase of volumes of morphological transforms is refined and used. The proposed surface area estimator is asymptotically unbiased in the case of sets contained in the ball centred at the origin with radius s and in the case of balls centred at the origin with unknown radius. For general shapes bounds for the asymptotic expected relative worst case error are given. A simulation example is discussed for surface area estimation based on 2×2×2-configurations.

  2. High surface area carbon and process for its production

    Energy Technology Data Exchange (ETDEWEB)

    Romanos, Jimmy; Burress, Jacob; Pfeifer, Peter; Rash, Tyler; Shah, Parag; Suppes, Galen

    2016-12-13

    Activated carbon materials and methods of producing and using activated carbon materials are provided. In particular, biomass-derived activated carbon materials and processes of producing the activated carbon materials with prespecified surface areas and pore size distributions are provided. Activated carbon materials with preselected high specific surface areas, porosities, sub-nm (<1 nm) pore volumes, and supra-nm (1-5 nm) pore volumes may be achieved by controlling the degree of carbon consumption and metallic potassium intercalation into the carbon lattice during the activation process.

  3. Surface barrier silicon detectors with a large active area

    International Nuclear Information System (INIS)

    Kim, Y.; Husimi, K.; Ikeda, Y.; Kim, C.; Ohkawa, S.; Sakai, T.

    1985-01-01

    Surface barrier silicon detectors with a large active area have been produced by using high resistive n-type silicon crystals, diameters of which are 3 to 5 inches. High quality detectors with a low leakage current and a low noise were achieved by developing the improved surface treatment. Characteristics of detectors obtained are good in energy resolution compared with conventional large area Si(Li) detectors. It has also been confirmed that local dead region is not found from measuring results of photo-pulse injection

  4. Stereological estimation of surface area from digital images

    DEFF Research Database (Denmark)

    Ziegel, Johanna; Kiderlen, Markus

    2010-01-01

    A sampling design of local stereology is combined with a method from digital stereology to yield a novel estimator of surface area based on counts of configurations observed in a digitization of an isotropic 2- dimensional slice with thickness s. As a tool, a result of the second author and J....... Rataj on infinitesimal increase of volumes of morphological transforms is refined and used. The proposed surface area estimator is asymptotically unbiased in the case of sets contained in the ball centred at the origin with radius s and in the case of balls centred at the origin with unknown radius...

  5. Determining Surface Roughness in Urban Areas Using Lidar Data

    Science.gov (United States)

    Holland, Donald

    2009-01-01

    An automated procedure has been developed to derive relevant factors, which can increase the ability to produce objective, repeatable methods for determining aerodynamic surface roughness. Aerodynamic surface roughness is used for many applications, like atmospheric dispersive models and wind-damage models. For this technique, existing lidar data was used that was originally collected for terrain analysis, and demonstrated that surface roughness values can be automatically derived, and then subsequently utilized in disaster-management and homeland security models. The developed lidar-processing algorithm effectively distinguishes buildings from trees and characterizes their size, density, orientation, and spacing (see figure); all of these variables are parameters that are required to calculate the estimated surface roughness for a specified area. By using this algorithm, aerodynamic surface roughness values in urban areas can then be extracted automatically. The user can also adjust the algorithm for local conditions and lidar characteristics, like summer/winter vegetation and dense/sparse lidar point spacing. Additionally, the user can also survey variations in surface roughness that occurs due to wind direction; for example, during a hurricane, when wind direction can change dramatically, this variable can be extremely significant. In its current state, the algorithm calculates an estimated surface roughness for a square kilometer area; techniques using the lidar data to calculate the surface roughness for a point, whereby only roughness elements that are upstream from the point of interest are used and the wind direction is a vital concern, are being investigated. This technological advancement will improve the reliability and accuracy of models that use and incorporate surface roughness.

  6. A method for increasing the surface area of perovskite-type oxides

    Indian Academy of Sciences (India)

    700oC (v), 800oC ( ) and without water treatment (U). The increase in the surface area of the perovskite-type oxides and the observed decrease in the crystal size by the steam treatment at 350–800oC are expected because of the recrystallization during the high temperature hydrothermal treatment depending upon the.

  7. Indexing Glomerular Filtration Rate to Body Surface Area

    DEFF Research Database (Denmark)

    Redal-Baigorri, Belén; Rasmussen, Knud; Heaf, James Goya

    2014-01-01

    BACKGROUND: Kidney function is mostly expressed in terms of glomerular filtration rate (GFR). A common feature is the expression as ml/min per 1.73 m(2) , which represents the adjustment of the individual kidney function to a standard body surface area (BSA) to allow comparison between individuals...

  8. Plasma Creatinine, Age and Body Surface Area in Nigerian Children ...

    African Journals Online (AJOL)

    In a bid to establish reference values for plasma creatinine in children and adolescents using age, and body surface area (BSA), 462 apparently healthy Nigerian children/adolescents aged one day to 15 years were studied. They were recruited from well baby clinics, as well as primary and secondary schools. Plasma ...

  9. Evaluation of five formulae for estimating body surface area of ...

    African Journals Online (AJOL)

    Background: Physiological functions are often assessed by standardizing for body surface area (BSA) to avoid excessive variation in calculations in pediatric practice. Aim: To explore the suitability of existing formulae for estimating the BSA of Nigerian children. Subjects and Methods: This cross‑sectional study involved ...

  10. (Impervious) Surfaces on the Microclimate of Urban Area

    African Journals Online (AJOL)

    The present paper shows the considerable impacts of both vegetated and synthetic surfaces on the microclimate of urban area. Vegetation of a particular place affects the microclimate through reduced solar radiation and lower air temperature due to shading and evapotranspiration. Lower air temperatures are essential ...

  11. Installation and performance evaluation of an indigenous surface area analyser

    International Nuclear Information System (INIS)

    Pillai, S.N.; Solapurkar, M.N.; Venkatesan, V.; Prakash, A.; Khan, K.B.; Kumar, Arun; Prasad, R.S.

    2014-01-01

    An indigenously available surface area analyser was installed inside glove box and checked for its performance by analyzing uranium oxide and thorium oxide powders at RMD. The unit has been made ready for analysis of Plutonium oxide powders after incorporating several important features. (author)

  12. Influence of Ear Surface Area on Heat Tolerance of Composite ...

    African Journals Online (AJOL)

    Low correlation (r = 0.12) was observed between body weight and ear width. There were no correlations between ear width, respiratory rates and pulse rate. However, a residual correlation (r = -0.03) was obtained between ear width and body temperature. Large ear surface area in composite rabbits enhances better ...

  13. Assessment of large aperture scintillometry for large-area surface ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 126; Issue 5. Assessment of large aperture scintillometry for large-area surface energy fluxes over an irrigated cropland in north India. Abhishek Danodia V K Sehgal N R Patel R Dhakar J Mukherjee S K Saha A Senthil Kumar. Volume 126 Issue 5 July 2017 Article ...

  14. Surface water and groundwater interaction in Marala - Khanki area, Punjab

    International Nuclear Information System (INIS)

    Akram, W.; Ahmad, M.; Latif, Z.; Tariq, J.A.; Malik, M.R.

    2011-07-01

    Isotope hydrological investigations were carried out in two selected areas of Indus Basin viz. Haripur Area and Chashma- Taunsa Area for elucidating various aspects of surface water and groundwater interaction. Groundwater samples were collected on seasonal basis (low and high river discharge periods) while surface water samples were collected more frequently (weekly or monthly basis). Isotopic data suggested that there is no contribution of surface water to groundwater recharge in Haripur Area and rain is the prevailing source of groundwater recharge. The data further revealed that isotopic values of the Haripur pocket of Tarbela Lake are higher than those of Main Lake / Indus River meaning that there is a significant contribution of base flow in this pocket. Indus River appeared to be the dominant source of groundwater recharge at most of the locations in Chashma- Taunsa Area. Isotopic data of Indus River showed an increase at Taunsa as compared to Chashma in low flow period indicating the high contribution of base flow at this point in time. Stable isotopes were successfully used to quantify the base flow contribution. (author)

  15. Growth of contact area between rough surfaces under normal stress

    Science.gov (United States)

    Stesky, R. M.; Hannan, S. S.

    1987-05-01

    The contact area between deforming rough surfaces in marble, alabaster, and quartz was measured from thin sections of surfaces bonded under load with low viscosity resin epoxy. The marble and alabaster samples had contact areas that increased with stress at an accelerating rate. This result suggests that the strength of the asperity contacts decreased progressively during the deformation, following some form of strain weakening relationship. This conclusion is supported by petrographic observation of the thin sections that indicate that much of the deformation was cataclastic, with minor twinning of calcite and kinking of gypsum. In the case of the quartz, the observed contact area was small and increased approximately linearly with normal stress. Only the irreversible cataclastic deformation was observed; however strain-induced birefringence and cracking of the epoxy, not observed with the other rocks, suggests that significant elastic deformation occurred, but recovered during unloading.

  16. Tropical cyclone rainfall area controlled by relative sea surface temperature.

    Science.gov (United States)

    Lin, Yanluan; Zhao, Ming; Zhang, Minghua

    2015-03-12

    Tropical cyclone rainfall rates have been projected to increase in a warmer climate. The area coverage of tropical cyclones influences their impact on human lives, yet little is known about how tropical cyclone rainfall area will change in the future. Here, using satellite data and global atmospheric model simulations, we show that tropical cyclone rainfall area is controlled primarily by its environmental sea surface temperature (SST) relative to the tropical mean SST (that is, the relative SST), while rainfall rate increases with increasing absolute SST. Our result is consistent with previous numerical simulations that indicated tight relationships between tropical cyclone size and mid-tropospheric relative humidity. Global statistics of tropical cyclone rainfall area are not expected to change markedly under a warmer climate provided that SST change is relatively uniform, implying that increases in total rainfall will be confined to similar size domains with higher rainfall rates.

  17. Variability of Surface Reflection Amplitudes of GPR Horn Antenna Depending on Distance between Antenna and Surface

    Directory of Open Access Journals (Sweden)

    Komačka Jozef

    2016-05-01

    Full Text Available The study focused on variability of surface reflections amplitudes of GPR horn antenna in relation to distance between an antenna and a surface is presented in the paper. The air-coupled antenna with the central frequency of 1 GHz was used in the investigation. Four types of surfaces (dry pavement, wet pavement, metal plate and composite layer from gypsum and wood were tested. The distance of antenna above the surfaces was changed in the range from 37.5 cm to 53.5 cm. The amplitudes of negative and positive peaks and their variability were analysed in relation to the distance of antenna above the surfaces. Moreover, the influence of changes in the peaks of negative and positive amplitudes on the total amplitudes was assessed. It was found out the amplitudes of negative peaks for all investigated surfaces were relatively consistent in the range from 40.5 cm to 48.5 cm and the moderate decline was identified in the case of amplitudes of positive peaks in the range of distances from 37.5 cm to 51.5 cm. This decline influences the tendency of total amplitudes. Based on the results of analysis it can be stated the distance of air-coupled antenna above the surface can influence the value of total amplitude and the differences depend on the type of surface.

  18. Spectral theory of infinite-area hyperbolic surfaces

    CERN Document Server

    Borthwick, David

    2016-01-01

    This text introduces geometric spectral theory in the context of infinite-area Riemann surfaces, providing a comprehensive account of the most recent developments in the field. For the second edition the context has been extended to general surfaces with hyperbolic ends, which provides a natural setting for development of the spectral theory while still keeping technical difficulties to a minimum. All of the material from the first edition is included and updated, and new sections have been added. Topics covered include an introduction to the geometry of hyperbolic surfaces, analysis of the resolvent of the Laplacian, scattering theory, resonances and scattering poles, the Selberg zeta function, the Poisson formula, distribution of resonances, the inverse scattering problem, Patterson-Sullivan theory, and the dynamical approach to the zeta function. The new sections cover the latest developments in the field, including the spectral gap, resonance asymptotics near the critical line, and sharp geometric constan...

  19. Thermal Desorption Analysis of Effective Specific Soil Surface Area

    Science.gov (United States)

    Smagin, A. V.; Bashina, A. S.; Klyueva, V. V.; Kubareva, A. V.

    2017-12-01

    A new method of assessing the effective specific surface area based on the successive thermal desorption of water vapor at different temperature stages of sample drying is analyzed in comparison with the conventional static adsorption method using a representative set of soil samples of different genesis and degree of dispersion. The theory of the method uses the fundamental relationship between the thermodynamic water potential (Ψ) and the absolute temperature of drying ( T): Ψ = Q - aT, where Q is the specific heat of vaporization, and a is the physically based parameter related to the initial temperature and relative humidity of the air in the external thermodynamic reservoir (laboratory). From gravimetric data on the mass fraction of water ( W) and the Ψ value, Polyanyi potential curves ( W(Ψ)) for the studied samples are plotted. Water sorption isotherms are then calculated, from which the capacity of monolayer and the target effective specific surface area are determined using the BET theory. Comparative analysis shows that the new method well agrees with the conventional estimation of the degree of dispersion by the BET and Kutilek methods in a wide range of specific surface area values between 10 and 250 m2/g.

  20. On the dependence of sea surface roughness on wind waves

    DEFF Research Database (Denmark)

    Johnson, H.K.; Højstrup, J.; Vested, H.J.

    1998-01-01

    The influence of wind waves on the momentum transfer (wind stress) between the atmosphere and sea surface was studied using new measured data from the RASEX experiment and other datasets compiled by Donelan et al. Results of the data analysis indicate that errors in wind friction velocity u...... that calculations of the wind friction velocities using the wave-spectra-dependent expression of Hansen and Larsen agrees quite well with measured values during RASEX. It also gives a trend in Charnock parameter consistent with that found by combining the field data. Last, calculations using a constant Charnock...... parameter (0.018) also give very good results for the wind friction velocities at the RASEX site....

  1. View-Dependent Tessellation and Simulation of Ocean Surfaces

    Directory of Open Access Journals (Sweden)

    Anna Puig-Centelles

    2014-01-01

    Full Text Available Modeling and rendering realistic ocean scenes have been thoroughly investigated for many years. Its appearance has been studied and it is possible to find very detailed simulations where a high degree of realism is achieved. Nevertheless, among the solutions to ocean rendering, real-time management of the huge heightmaps that are necessary for rendering an ocean scene is still not solved. We propose a new technique for simulating the ocean surface on GPU. This technique is capable of offering view-dependent approximations of the mesh while maintaining coherence among the extracted approximations. This feature is very important as most solutions previously presented must retessellate from the initial mesh. Our solution is able to use the latest extracted approximation when refining or coarsening the mesh.

  2. Solvent accessible surface area (ASA) of simulated phospholipid membranes

    DEFF Research Database (Denmark)

    Tuchsen, E.; Jensen, Morten Østergaard; Westh, P.

    2003-01-01

    The membrane-solvent interface has been investigated through calculations of the solvent accessible surface area (ASA) for simulated membranes of DPPC and POPE. For DPPC at 52 degreesC we found an ASA of 126 +/- 8 Angstrom(2) per lipid molecule, equivalent to twice the projected lateral area......, even the most exposed parts of the PC head-group show average ASAs of less than half of its maximal or 'fully hydrated' value. The average ASA of a simulated POPE membrane was 96 +/- 7 Angstrom(2) per lipid. The smaller value than for DPPC reflects much lower ASA of the ammonium ion, which is partially...... compensated by increased exposure of the ethylene and phosphate moieties. The ASA of the polar moieties Of (PO4, NH3 and COO) constitutes 65% of the total accessible area for POPE, making this interface more polar than that of DPPC. It is suggested that ASA information can be valuable in attempts...

  3. An estimation of tourism dependence in French rural areas

    OpenAIRE

    Dissart, Jean-Christophe; Aubert, Francis; Truchet, Stéphanie; European Regional Science Association; Association de Science Régionale de Langue Française

    2007-01-01

    This paper intends to estimate the importance of tourism in the economy of rural areas. Considering previous analyses of rural dynamics, this paper 1) focuses on tourism activity, 2) analyzes the situation of Functional Economic Areas, and 3) takes into account socioeconomic indicators as well as landscape features. Based on secondary data, resource like regions are defined, the local share of tourism employment is estimated, stylized facts regarding tourism indicators by cluster are produced...

  4. Regime-dependent determinants of Euro area sovereign CDS spreads

    NARCIS (Netherlands)

    Blommestein, H.J.; Eijffinger, Sylvester; Qian, Zongxin

    We study the determinants of sovereign CDS spreads of five Euro area countries (Greece, Ireland, Italy, Portugal, and Spain) after the collapse of Lehman Brothers. We find that global and/or European Monetary Union (EMU)-wide factors are the main drivers of changes in the sovereign CDS spreads in

  5. Metal-organic framework materials with ultrahigh surface areas

    Science.gov (United States)

    Farha, Omar K.; Hupp, Joseph T.; Wilmer, Christopher E.; Eryazici, Ibrahim; Snurr, Randall Q.; Gomez-Gualdron, Diego A.; Borah, Bhaskarjyoti

    2015-12-22

    A metal organic framework (MOF) material including a Brunauer-Emmett-Teller (BET) surface area greater than 7,010 m.sup.2/g. Also a metal organic framework (MOF) material including hexa-carboxylated linkers including alkyne bond. Also a metal organic framework (MOF) material including three types of cuboctahedron cages fused to provide continuous channels. Also a method of making a metal organic framework (MOF) material including saponifying hexaester precursors having alkyne bonds to form a plurality of hexa-carboxylated linkers including alkyne bonds and performing a solvothermal reaction with the plurality of hexa-carboxylated linkers and one or more metal containing compounds to form the MOF material.

  6. Asymptotic variance of grey-scale surface area estimators

    DEFF Research Database (Denmark)

    Svane, Anne Marie

    Grey-scale local algorithms have been suggested as a fast way of estimating surface area from grey-scale digital images. Their asymptotic mean has already been described. In this paper, the asymptotic behaviour of the variance is studied in isotropic and sufficiently smooth settings, resulting...... in a general asymptotic bound. For compact convex sets with nowhere vanishing Gaussian curvature, the asymptotics can be described more explicitly. As in the case of volume estimators, the variance is decomposed into a lattice sum and an oscillating term of at most the same magnitude....

  7. Pore Scale Heterogeneity in the Mineral Distribution, Surface Area and Adsorption in Porous Rocks

    Science.gov (United States)

    Lai, P. E. P.; Krevor, S. C.

    2014-12-01

    The impact of heterogeneity in chemical transport and reaction is not understood in continuum (Darcy/Fickian) models of reactive transport. This is manifested in well-known problems such as scale dependent dispersion and discrepancies in reaction rate observations made at laboratory and field scales [1]. Additionally, this is a source of uncertainty for carbon dioxide injection, which produces a reactive fluid-rock system particularly in carbonate rock reservoirs. A potential cause is the inability of the continuum approach to incorporate the impact of heterogeneity in pore-scale reaction rates. This results in part from pore-scale heterogeneities in surface area of reactive minerals [2, 3]. We use x-ray micro tomography to describe the non-normal 3-dimensional distribution of reactive surface area within a porous medium according to distinct mineral groups. Using in-house image processing techniques, thin sections, nitrogen BET surface area, backscattered electron imaging and energy dispersive spectroscopy, we compare the surface area of each mineral phase to those obtained from x-ray CT imagery. In all samples, there is little correlation between the reactive surface area fraction and the volumetric fraction of a mineral in a bulk rock. Berea sandstone was far less heterogeneous and has a characteristic pore size at which a surface area distribution may be used to quantify heterogeneity. In carbonates, heterogeneity is more complex and surface area must be characterized at multiple length scales for an accurate description of reactive transport. We combine the mineral specific surface area characterisation to dynamic tomography, imaging the flow of water and solutes, to observe flow dependent and mineral specific adsorption. The observations may contribute to the incorporation of experimentally based statistical descriptions of pore scale heterogeneity in reactive transport into upscaled models, moving it closer to predictive capabilities for field scale

  8. Overcoming the reference large-area sources non-uniformity in surface area monitor calibration

    Energy Technology Data Exchange (ETDEWEB)

    Junior, Iremar Alves S.; Siqueira, Paulo de T.D.; Xavier, Marcs; Nascimento, Eduardo do; Potiens, Maria da Penha A., E-mail: iremarjr@usp.br, E-mail: ptsiquei@ipen.br, E-mail: mxavier@ipen.br, E-mail: eduardon@ufba.br, E-mail: mppalbu@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    This paper describes a study using MCNP5 simulations, a Monte Carlo based radiation transport code, in order to evaluate the possibility of using reference large-area sources that do not meet the uniformity recommendations of the ISO 8769:2010 in surface contamination monitors calibration. {sup 14}C, {sup 36}Cl, {sup 99}Tc, {sup 137}Cs and {sup 90}Sr + {sup 90}Y large area reference sources were simulated as well as the setup and the detector probe. Simulations were carried out for both uniform and non-uniform surface distributions. In the case of uniform distribution, specific weights for each region were considered, as obtained in the uniformity evaluation measurements. To each simulation, it was considered the average number of signals generated in each detector probe, i.e., it was determined the fraction of stories depositing energy in the corresponding gas filled region of the detector. Simulations results show differences in detection efficiency values up to 15%. (author)

  9. Spatial dependency of cholera prevalence on potential cholera reservoirs in an urban area, Kumasi, Ghana

    Science.gov (United States)

    Osei, Frank B.; Duker, Alfred A.; Augustijn, Ellen-Wien; Stein, Alfred

    2010-10-01

    Cholera has been a public health burden in Ghana since the early 1970s. Between 1999 and 2005, a total of 25,636 cases and 620 deaths were officially reported to the WHO. In one of the worst affected urban cities, fecal contamination of surface water is extremely high, and the disease is reported to be prevalent among inhabitants living in close proximity to surface water bodies. Surface runoff from dump sites is a major source of fecal and bacterial contamination of rivers and streams in the study area. This study aims to determine (a) the impacts of surface water contamination on cholera infection and (b) detect and map arbitrary shaped clusters of cholera. A Geographic Information System (GIS) based spatial analysis is used to delineate potential reservoirs of the cholera vibrios; possibly contaminated by surface runoff from open space refuse dumps. Statistical modeling using OLS model reveals a significant negative association between (a) cholera prevalence and proximity to all the potential cholera reservoirs ( R2 = 0.18, p < 0.001) and (b) cholera prevalence and proximity to upstream potential cholera reservoirs ( R2 = 0.25, p < 0.001). The inclusion of spatial autoregressive coefficients in the OLS model reveals the dependency of the spatial distribution of cholera prevalence on the spatial neighbors of the communities. A flexible scan statistic identifies a most likely cluster with a higher relative risk (RR = 2.04, p < 0.01) compared with the cluster detected by circular scan statistic (RR = 1.60, p < 0.01). We conclude that surface water pollution through runoff from waste dump sites play a significant role in cholera infection.

  10. Changes in thickness and surface area of the human cortex and their relationship with intelligence.

    Science.gov (United States)

    Schnack, Hugo G; van Haren, Neeltje E M; Brouwer, Rachel M; Evans, Alan; Durston, Sarah; Boomsma, Dorret I; Kahn, René S; Hulshoff Pol, Hilleke E

    2015-06-01

    Changes in cortical thickness over time have been related to intelligence, but whether changes in cortical surface area are related to general cognitive functioning is unknown. We therefore examined the relationship between intelligence quotient (IQ) and changes in cortical thickness and surface over time in 504 healthy subjects. At 10 years of age, more intelligent children have a slightly thinner cortex than children with a lower IQ. This relationship becomes more pronounced with increasing age: with higher IQ, a faster thinning of the cortex is found over time. In the more intelligent young adults, this relationship reverses so that by the age of 42 a thicker cortex is associated with higher intelligence. In contrast, cortical surface is larger in more intelligent children at the age of 10. The cortical surface is still expanding, reaching its maximum area during adolescence. With higher IQ, cortical expansion is completed at a younger age; and once completed, surface area decreases at a higher rate. These findings suggest that intelligence may be more related to the magnitude and timing of changes in brain structure during development than to brain structure per se, and that the cortex is never completed but shows continuing intelligence-dependent development. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  11. Periodic Mesoporous Organosilica Nanocubes with Ultrahigh Surface Areas for Efficient CO2 Adsorption

    Science.gov (United States)

    Wei, Yong; Li, Xiaomin; Zhang, Renyuan; Liu, Yong; Wang, Wenxing; Ling, Yun; El-Toni, Ahmed Mohamed; Zhao, Dongyuan

    2016-02-01

    Ultrahigh surface area single-crystals of periodic mesoporous organosilica (PMOs) with uniform cubic or truncated-cubic morphology and organic/inorganic components homogeneously distributed over the whole frameworks have successfully been prepared by a sol-gel surfactant-templating method. By tuning the porous feature and polymerization degree, the surface areas of the obtained PMO nanocubes can reach as high as 2370 m2/g, which is the highest for silica-based mesoporous materials. The ultrahigh surface area of the obtained PMO single crystals is mainly resulted from abundant micropores in the mesoporous frameworks. Furthermore, the diameter of the nanocubes can also be well controlled from 150 to 600 nm. The materials show ultrahigh CO2 adsorption capacity (up to 1.42 mmol/g at 273 K) which is much higher than other porous silica materials and comparable to some carbonaceous materials. The adsorption of CO2 into the PMO nanocubes is mainly in physical interaction, therefore the adsorption-desorption process is highly reversible and the adsorption capacity is much dependent on the surface area of the materials. Moreover, the selectivity is also very high (~11 times to N2) towards CO2 adsorption.

  12. Method for producing high surface area chromia materials for catalysis

    Science.gov (United States)

    Gash, Alexander E [Brentwood, CA; Satcher, Joe [Patterson, CA; Tillotson, Thomas [Tracy, CA; Hrubesh, Lawrence [Pleasanton, CA; Simpson, Randall [Livermore, CA

    2007-05-01

    Nanostructured chromium(III)-oxide-based materials using sol-gel processing and a synthetic route for producing such materials are disclosed herein. Monolithic aerogels and xerogels having surface areas between 150 m.sup.2/g and 520 m.sup.2/g have been produced. The synthetic method employs the use of stable and inexpensive hydrated-chromium(III) inorganic salts and common solvents such as water, ethanol, methanol, 1-propanol, t-butanol, 2-ethoxy ethanol, and ethylene glycol, DMSO, and dimethyl formamide. The synthesis involves the dissolution of the metal salt in a solvent followed by an addition of a proton scavenger, such as an epoxide, which induces gel formation in a timely manner. Both critical point (supercritical extraction) and atmospheric (low temperature evaporation) drying may be employed to produce monolithic aerogels and xerogels, respectively.

  13. Fully automated algorithm for wound surface area assessment.

    Science.gov (United States)

    Deana, Alessandro Melo; de Jesus, Sérgio Henrique Costa; Sampaio, Brunna Pileggi Azevedo; Oliveira, Marcelo Tavares; Silva, Daniela Fátima Teixeira; França, Cristiane Miranda

    2013-01-01

    Worldwide, clinicians, dentists, nurses, researchers, and other health professionals need to monitor the wound healing progress and to quantify the rate of wound closure. The aim of this study is to demonstrate, step by step, a fully automated numerical method to estimate the size of the wound and the percentage damaged relative to the body surface area (BSA) in images, without the requirement for human intervention. We included the formula for BSA in rats in the algorithm. The methodology was validated in experimental wounds and human ulcers and was compared with the analysis of an experienced pathologist, with good agreement. Therefore, this algorithm is suitable for experimental wounds and burns and human ulcers, as they have a high contrast with adjacent normal skin. © 2013 by the Wound Healing Society.

  14. Electromagnetic surface waves for large-area RF plasma productions between large-area planar electrodes

    International Nuclear Information System (INIS)

    Nonaka, S.

    1992-01-01

    Recently, large-area plasma production has been tested by means of a 13.56 MHz radio-frequency (RF) discharge between a pair of large-area planar electrodes, approximately 0.5 m x 1.4 m, as one of the semiconductor technologies for fabrication of large-area amorphous silicon solar cells in the ''Sunshine Project'' of the Agency of Industrial Science and Technology in Japan. We also confirmed long plasma production between a pair of long electrodes. In this paper, normal electromagnetic (EM) waves propagating in a region between a planar waveguide with one plasma and two dielectric layers are analyzed in order to study the feasibility of large-area plasma productions by EM wave-discharges between a pair of large-area RF electrodes larger than the half-wavelength of RF wave. In conclusion, plasmas higher than an electron plasma frequency will be produced by an odd TMoo surface mode. (author) 4 refs., 3 figs

  15. Human cortical areas involved in perception of surface glossiness.

    Science.gov (United States)

    Wada, Atsushi; Sakano, Yuichi; Ando, Hiroshi

    2014-09-01

    Glossiness is the visual appearance of an object's surface as defined by its surface reflectance properties. Despite its ecological importance, little is known about the neural substrates underlying its perception. In this study, we performed the first human neuroimaging experiments that directly investigated where the processing of glossiness resides in the visual cortex. First, we investigated the cortical regions that were more activated by observing high glossiness compared with low glossiness, where the effects of simple luminance and luminance contrast were dissociated by controlling the illumination conditions (Experiment 1). As cortical regions that may be related to the processing of glossiness, V2, V3, hV4, VO-1, VO-2, collateral sulcus (CoS), LO-1, and V3A/B were identified, which also showed significant correlation with the perceived level of glossiness. This result is consistent with the recent monkey studies that identified selective neural response to glossiness in the ventral visual pathway, except for V3A/B in the dorsal visual pathway, whose involvement in the processing of glossiness could be specific to the human visual system. Second, we investigated the cortical regions that were modulated by selective attention to glossiness (Experiment 2). The visual areas that showed higher activation to attention to glossiness than that to either form or orientation were identified as right hV4, right VO-2, and right V3A/B, which were commonly identified in Experiment 1. The results indicate that these commonly identified visual areas in the human visual cortex may play important roles in glossiness perception. Copyright © 2014. Published by Elsevier Inc.

  16. Time-Dependent Wetting Behavior of PDMS Surfaces with Bioinspired, Hierarchical Structures.

    Science.gov (United States)

    Mishra, Himanshu; Schrader, Alex M; Lee, Dong Woog; Gallo, Adair; Chen, Szu-Ying; Kaufman, Yair; Das, Saurabh; Israelachvili, Jacob N

    2016-03-01

    Wetting of rough surfaces involves time-dependent effects, such as surface deformations, nonuniform filling of surface pores within or outside the contact area, and surface chemistries, but the detailed impact of these phenomena on wetting is not entirely clear. Understanding these effects is crucial for designing coatings for a wide range of applications, such as membrane-based oil-water separation and desalination, waterproof linings/windows for automobiles, aircrafts, and naval vessels, and antibiofouling. Herein, we report on time-dependent contact angles of water droplets on a rough polydimethylsiloxane (PDMS) surface that cannot be completely described by the conventional Cassie-Baxter or Wenzel models or the recently proposed Cassie-impregnated model. Shells of sand dollars (Dendraster excentricus) were used as lithography-free, robust templates to produce rough PDMS surfaces with hierarchical, periodic features ranging from 1 × 10(-7) to 1 × 10(-4) m. Under saturated vapor conditions, we found that in the short term (<1 min), the contact angle of a sessile water droplet on the templated PDMS, θ(SDT) = 140 ± 3°, was accurately described by the Cassie-Baxter model (predicted θ(SDT) = 137°); however, after 90 min, θ(SDT) fell to 110°. Fluorescent confocal microscopy confirmed that the initial reduction in θ(SDT) to 110° (the Wenzel limit) was primarily a Cassie-Baxter to Wenzel transition during which pores within the contact area filled gradually, and more rapidly for ethanol-water mixtures. After 90 min, the contact line of the water droplet became pinned, perhaps caused by viscoelastic deformation of the PDMS around the contact line, and a significant volume of water began to flow from the droplet to pores outside the contact region, causing θ(SDT) to decrease to 65° over 48 h on the rough surface. The system we present here to explore the concept of contact angle time dependence (dynamics) and modeling of natural surfaces provides insights

  17. Time-Dependent Wetting Behavior of PDMS Surfaces with Bio-Inspired, Hierarchical Structures

    KAUST Repository

    Mishra, Himanshu

    2015-12-28

    Wetting of rough surfaces involves time-dependent effects, such as surface deformations, non-uniform filling of surface pores within or outside the contact area, and surface chemistries, but the detailed impact of these phenomena on wetting is not entirely clear. Understanding these effects is crucial for designing coatings for a wide range of applications, such as membrane-based oil-water separation and desalination, waterproof linings/windows for automobiles, aircrafts, and naval vessels, and antibiofouling. Herein, we report on time-dependent contact angles of water droplets on a rough polydimethylsiloxane (PDMS) surface that cannot be completely described by the conventional Cassie-Baxter or Wenzel models or the recently proposed Cassie-impregnated model. Shells of sand dollars (Dendraster excentricus) were used as lithography-free, robust templates to produce rough PDMS surfaces with hierarchical, periodic features ranging from 10-7-10-4 m. Under saturated vapor conditions, we found that in the short-term (<1 min), the contact angle of a sessile water droplet on the templated PDMS, θSDT = 140° ± 3°, was accurately described by the Cassie-Baxter model (predicted θSDT = 137°); however, after 90 min, θSDT fell to 110°. Fluorescent confocal microscopy confirmed that the initial reduction in θSDT to 110° (the Wenzel limit) was primarily a Cassie-Baxter to Wenzel transition during which pores within the contact area filled gradually, and more rapidly for ethanol-water mixtures. After 90 min, the contact line of the water droplet became pinned, perhaps caused by viscoelastic deformation of the PDMS around the contact line, and a significant volume of water began to flow from the droplet to pores outside the contact region, causing θSDT to decrease to 65° over 48 h on the rough surface. The system we present here to explore the concept of contact angle time dependence (dynamics) and modeling of natural surfaces provides insights into the design and

  18. Assessment of Surface Area Characteristics of Dental Implants with Gradual Bioactive Surface Treatment

    Science.gov (United States)

    Czan, Andrej; Babík, Ondrej; Miklos, Matej; Záušková, Lucia; Mezencevová, Viktória

    2017-10-01

    Since most of the implant surface is in direct contact with bone tissue, shape and integrity of said surface has great influence on successful osseointegration. Among other characteristics that predetermine titanium of different grades of pureness as ideal biomaterial, titanium shows high mechanical strength making precise miniature machining increasingly difficult. Current titanium-based implants are often anodized due to colour coding. This anodized layer has important functional properties for right usage and also bio-compatibility of dental implants. Physical method of anodizing and usage of anodizing mediums has a significant influence on the surface quality and itself functionality. However, basic requirement of the dental implant with satisfactory properties is quality of machined surface before anodizing. Roughness, for example, is factor affecting of time length of anodizing operation and so whole productivity. The paper is focused on monitoring of surface and area characteristics, such as roughness or surface integrity after different cutting conditions of miniature machining of dental implants and their impact on suitability for creation of satisfactory anodized layer with the correct biocompatible functional properties.

  19. Surface ozone in the urban area of Manaus, Amazonas, Brazil

    Science.gov (United States)

    Souza, R. A. F. D.; Costa, P. S.; Silva, C.; Godoi, R. M.; Martin, S. T.; Tota, J.; Barbosa, H. M.; Pauliquevis, T.; Ferreira De Brito, J.; Artaxo, P.; Manzi, A. O.; Wolf, S. A.; Cirino, G. G.

    2014-12-01

    When nitrogen oxides from vehicle and industrial emissions mix with volatile organic compounds from trees and plants with exposure to sunlight, a chemical reaction occurs contributing to ground-level ozone pollution. The preliminary results of the surface ozone study in urban area of Manaus, Amazonas State, Brazil, are presented for the first intensive operating period (IOP1) of the GoAmazon experiment (February/March 2014). Photochemical ozone production was found to be a regular process, with an afternoon maximum of the ozone mixing ratio of lower than 20 ppbv for cloudy days or clear sky weather. Typical ozone concentrations at mid-day were low (about 10 ppb). On the other hand, several high-value ozone episodes with surface ozone mixing ratios up to three times larger were registered during the dry season of 2013 (September/October). At the beginning of the wet season, the ozone concentration in Manaus decreased significantly, but diurnal variations can be found during the days with rainfall and other fast changes of meteorological conditions. Possible explanations of the nature of pulsations are discussed. Photochemical ozone production by local urban plumes of Manaus is named as a first possible source of the ozone concentration and biomass burning or power plant emissions are suggested as an alternative or an additional source.

  20. NEW CONCEPTS AND TEST METHODS OF CURVE PROFILE AREA DENSITY IN SURFACE: ESTIMATION OF AREAL DENSITY ON CURVED SPATIAL SURFACE

    OpenAIRE

    Hong Shen

    2011-01-01

    The concepts of curve profile, curve intercept, curve intercept density, curve profile area density, intersection density in containing intersection (or intersection density relied on intersection reference), curve profile intersection density in surface (or curve intercept intersection density relied on intersection of containing curve), and curve profile area density in surface (AS) were defined. AS expressed the amount of curve profile area of Y phase in the unit containing surface area, S...

  1. Detailed effects of particle size and surface area on 222Rn emanation of a phosphate rock.

    Science.gov (United States)

    Haquin, Gustavo; Yungrais, Zohar; Ilzycer, Danielle; Zafrir, Hovav; Weisbrod, Noam

    2017-12-01

    The dependency of radon emanation on soil texture was investigated using the closed chamber method. Ground phosphate rock with a large specific surface area was analyzed, and the presence of inner pores, as well as a high degree of roughness and heterogeneity in the phosphate particles, was found. The average radon emanation of the dry phosphate was 0.145 ± 0.016. The emanation coefficient was highest (0.169 ± 0.019) for the smallest particles (210 μm). The reduction rate followed an inverse power law. As expected, a linear dependence between the emanation coefficient and the specific surface area was found, being lower than predicted for the large specific surface area. This was most likely due to an increase in the embedding effect of radon atoms in adjacent grains separated by micropores. Results indicate that knowledge of grain radium distribution is crucial to making accurate emanation predictions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Moving to 3D: relationships between coral planar area, surface area and volume.

    Science.gov (United States)

    House, Jenny E; Brambilla, Viviana; Bidaut, Luc M; Christie, Alec P; Pizarro, Oscar; Madin, Joshua S; Dornelas, Maria

    2018-01-01

    Coral reefs are a valuable and vulnerable marine ecosystem. The structure of coral reefs influences their health and ability to fulfill ecosystem functions and services. However, monitoring reef corals largely relies on 1D or 2D estimates of coral cover and abundance that overlook change in ecologically significant aspects of the reefs because they do not incorporate vertical or volumetric information. This study explores the relationship between 2D and 3D metrics of coral size. We show that surface area and volume scale consistently with planar area, albeit with morphotype specific conversion parameters. We use a photogrammetric approach using open-source software to estimate the ability of photogrammetry to provide measurement estimates of corals in 3D. Technological developments have made photogrammetry a valid and practical technique for studying coral reefs. We anticipate that these techniques for moving coral research from 2D into 3D will facilitate answering ecological questions by incorporating the 3rd dimension into monitoring.

  3. Adsorption of tetracycline on kaolinite with pH-dependent surface charges.

    Science.gov (United States)

    Li, Zhaohui; Schulz, Laura; Ackley, Caren; Fenske, Nancy

    2010-11-01

    Kaolinite is a major type of clay minerals in soils of warm and humid climate. Although it has a much lower cation exchange capacity (CEC) and specific surface area compared to swelling clays, its ubiquitous existence as well as its pH-dependent surface charge makes it an important component to study the interactions between contaminants and soils. Tetracycline (TC) is a group of broad spectrum antibiotics used extensively in human and veterinary medicine. It has a high aqueous solubility and a long environmental half-life. In this study, the interactions between TC and kaolinite in aqueous solution were investigated in batch tests and supplemented by FTIR analyses. The adsorption of TC on kaolinite was mainly on the external surfaces via cation exchange as confirmed by stoichiometric desorption of exchangeable cations and simultaneous adsorption of H(+) rather than due to complexation. Under acidic conditions, a reduction in surface charge, thus the CEC, resulted in more desorption of exchangeable cations compared to TC adsorption. Fitting of the experimental data to the adsorption of different species revealed that TC(+) accounted for 4/5 of the total TC adsorbed with the remaining by zwitterion TC(0), possible via hydrogen bonding. At higher temperature, the pKa2 and pKa3 values seem to shift a pH unit lower. Due to its pH-dependent charge of kaolinite, TC adsorption is more pH dependent. The TC adsorption capacity on kaolinite was much lower compared to that on swelling clays. However, the adsorption rate constant was faster than that on swelling clays owing to surface adsorption instead of intercalation. Despite its low TC adsorption capacity, the ubiquitous existence of kaolinite in soils of warm climate may play a vital role in the fate and transport of TC in these soils. Copyright 2010 Elsevier Inc. All rights reserved.

  4. Rate-Dependent Slip of Newtonian Liquid at Smooth Surfaces

    International Nuclear Information System (INIS)

    Zhu, Yingxi; Granick, Steve

    2001-01-01

    Newtonian fluids were placed between molecularly smooth surfaces whose spacing was vibrated at spacings where the fluid responded as a continuum. Hydrodynamic forces agreed with predictions from the no-slip boundary condition only provided that flow rate (peak velocity normalized by spacing) was low, but implied partial slip when it exceeded a critical level, different in different systems, correlated with contact angle (surface wettability). With increasing flow rate and partially wetted surfaces, hydrodynamic forces became up to 2--4 orders of magnitude less than expected by assuming the no-slip boundary condition that is commonly stated in textbooks

  5. The protection of urban areas from surface wastewater pollutions

    Directory of Open Access Journals (Sweden)

    Vialkova Elena

    2017-01-01

    Full Text Available In this paper it considered the problem of collection, treatment and discharge into waters of rain and melted wastewater. To reduce the load on the combined sewer system, there are engineering solutions collect rain and melt water for use in the irrigation of lawns and green spaces. Research carried out at the department “Water supply and sanitation”, (Russia, confirm the high pollution concentrations of meltwater and rainfall in urban arias. Series of measurements of heavy metal in rainwater runoff carried out in Hungary demonstrates clearly the differences in concentrations in the function of distance from the edge of the road. Also differences are introduced between pollution concentrations in runoff water from within and outside urban traffic roads. The quality of snow cover, forming meltwater is observed to be changing in dependence on roadway location. Quality characteristics of surface runoff and its sediments can be effectively improved with super-high frequency radiation (SHF treatment which is presented in this paper.

  6. Extent of Stream Burial and Relationships to Watershed Area, Topography, and Impervious Surface Area

    Directory of Open Access Journals (Sweden)

    Roy E. Weitzell

    2016-11-01

    Full Text Available Stream burial—the routing of streams through culverts, pipes, and concrete lined channels, or simply paving them over—is common during urbanization, and disproportionately affects small, headwater streams. Burial undermines the physical and chemical processes governing life in streams, with consequences for water quality and quantity that may amplify from headwaters to downstream receiving waters. Knowledge of the extent of stream burial is critical for understanding cumulative impacts to stream networks, and for future decision-making allowing for urban development while protecting ecosystem function. We predicted stream burial across the urbanizing Potomac River Basin (USA for each 10-m stream segment in the basin from medium-resolution impervious cover data and training observations obtained from high-resolution aerial photography in a GIS. Results were analyzed across a range in spatial aggregation, including counties and independent cities, small watersheds, and regular spatial grids. Stream burial was generally correlated with total impervious surface area (ISA, with areas exhibiting ISA above 30% often subject to elevated ratios of stream burial. Recurring patterns in burial predictions related to catchment area and topographic slope were also detected. We discuss these results in the context of physiographic constraints on stream location and urban development, including implications for environmental management of aquatic resources.

  7. Energy dependent neutron sputtering and surface damage cross sections

    International Nuclear Information System (INIS)

    Odette, G.R.; Doiron, D.R.; Kennerley, R.J.

    1976-01-01

    The results clearly indicate that damage function analysis might be usefully applied to define both the neutron and primary recoil energy dependence of sputtering yields. Even with relatively large data errors, it appears that it is possible to both detect the existence and indicate the form of the deviation of sputtering yield from linear damage energy dependence (if such deviation exists). This information would be very useful in developing improved models of the sputtering phenomena

  8. Layer-dependent surface potential of phosphorene and anisotropic/layer-dependent charge transfer in phosphorene-gold hybrid systems.

    Science.gov (United States)

    Xu, Renjing; Yang, Jiong; Zhu, Yi; Yan, Han; Pei, Jiajie; Myint, Ye Win; Zhang, Shuang; Lu, Yuerui

    2016-01-07

    The surface potential and the efficiency of interfacial charge transfer are extremely important for designing future semiconductor devices based on the emerging two-dimensional (2D) phosphorene. Here, we directly measured the strong layer-dependent surface potential of mono- and few-layered phosphorene on gold, which is consistent with the reported theoretical prediction. At the same time, we used an optical way photoluminescence (PL) spectroscopy to probe charge transfer in the phosphorene-gold hybrid system. We firstly observed highly anisotropic and layer-dependent PL quenching in the phosphorene-gold hybrid system, which is attributed to the highly anisotropic/layer-dependent interfacial charge transfer.

  9. Climatologies at high resolution for the earth's land surface areas

    Science.gov (United States)

    Karger, Dirk Nikolaus; Conrad, Olaf; Böhner, Jürgen; Kawohl, Tobias; Kreft, Holger; Soria-Auza, Rodrigo Wilber; Zimmermann, Niklaus E.; Linder, H. Peter; Kessler, Michael

    2017-09-01

    High-resolution information on climatic conditions is essential to many applications in environmental and ecological sciences. Here we present the CHELSA (Climatologies at high resolution for the earth's land surface areas) data of downscaled model output temperature and precipitation estimates of the ERA-Interim climatic reanalysis to a high resolution of 30 arc sec. The temperature algorithm is based on statistical downscaling of atmospheric temperatures. The precipitation algorithm incorporates orographic predictors including wind fields, valley exposition, and boundary layer height, with a subsequent bias correction. The resulting data consist of a monthly temperature and precipitation climatology for the years 1979-2013. We compare the data derived from the CHELSA algorithm with other standard gridded products and station data from the Global Historical Climate Network. We compare the performance of the new climatologies in species distribution modelling and show that we can increase the accuracy of species range predictions. We further show that CHELSA climatological data has a similar accuracy as other products for temperature, but that its predictions of precipitation patterns are better.

  10. Surface Rupture Effects on Earthquake Moment-Area Scaling Relations

    Science.gov (United States)

    Luo, Yingdi; Ampuero, Jean-Paul; Miyakoshi, Ken; Irikura, Kojiro

    2017-09-01

    Empirical earthquake scaling relations play a central role in fundamental studies of earthquake physics and in current practice of earthquake hazard assessment, and are being refined by advances in earthquake source analysis. A scaling relation between seismic moment ( M 0) and rupture area ( A) currently in use for ground motion prediction in Japan features a transition regime of the form M 0- A 2, between the well-recognized small (self-similar) and very large (W-model) earthquake regimes, which has counter-intuitive attributes and uncertain theoretical underpinnings. Here, we investigate the mechanical origin of this transition regime via earthquake cycle simulations, analytical dislocation models and numerical crack models on strike-slip faults. We find that, even if stress drop is assumed constant, the properties of the transition regime are controlled by surface rupture effects, comprising an effective rupture elongation along-dip due to a mirror effect and systematic changes of the shape factor relating slip to stress drop. Based on this physical insight, we propose a simplified formula to account for these effects in M 0- A scaling relations for strike-slip earthquakes.

  11. Dependence of metal-enhanced fluorescence on surface roughness

    Science.gov (United States)

    François, Alexandre; Sciacca, Beniamino; Zuber, Agnieszka; Klantsataya, Elizaveta; Monro, Tanya M.

    2014-03-01

    Metal Enhanced Fluorescence (MEF) takes advantage of the coupling between surface plasmons, in either a metallic thin film or metallic nanoparticles, and fluorophores located in proximity of the metal, yielding an increase of the fluorophore emission. While MEF has been widely studied on metallic nanoparticles with the emphasis on creating brighter fluorescent labels, planar surfaces have not benefitted from the same attention. Here we investigate the influence of the surface roughness of a thin metallic film on the fluorescence enhancement. 50nm thick silver films were deposited on glass slides using either thermal evaporation with different evaporation currents or an electroless plating method based on the Tollens reaction to vary the surface roughness. Multiple layers of positively and negatively charged polyelectrolytes were deposited on top of the metallic coating to map out the enhancement factor as function of the gap between the metallic coating and fluorophore molecules covalently bound to the last polyelectrolyte layer. We show that fluorescence is enhanced by the presence of the metallic film, and in particular that the enhancement increases by a factor 3 to 40 for roughness ranging from 3 nm to 8 nm. Although these enhancement factors are modest compared to the enhancement produced by complex metallic nanoparticles or nano-patterned metallic thin films, the thin films used here are capable of supporting a plasmonic wave and offer the possibility of combining different techniques, such as surface plasmon resonance (with its higher refractive index sensitivity compared to localized plasmons) and MEF within a single device.

  12. Surface and subsurface conditions in permafrost areas - a literature review

    International Nuclear Information System (INIS)

    Vidstrand, Patrik

    2003-02-01

    This report contains a summary of some of the information within existing technical and scientific literature on permafrost. Permafrost is viewed as one of the future climate driven process domains that may exist in Scandinavia, and that may give rise to significantly different surface and subsurface conditions than the present. Except for changes in the biosphere, permafrost may impact hydraulic, mechanical, and chemical subsurface processes and conditions. Permafrost and its influences on the subsurface conditions are thus of interest for the performance and safety assessments of deep geological waste repositories. The definition of permafrost is 'ground that stays at or below 0 deg C for at least two consecutive years'. Permafrost will effect the geological subsurface to some depth. How deep the permafrost may grow is a function of the heat balance, thermal conditions at the surface and within the ground, and the geothermal heat flux from the Earth's inner parts. The main chapters of the report summaries the knowledge on permafrost evolution, occurrence and distribution, and extracts information concerning hydrology and mechanical and chemical impacts due to permafrost related conditions. The results of a literature review are always dependent on the available literature. Concerning permafrost there is some literature available from investigations in the field of long-term repositories and some from mining industries. However, reports of these investigations are few and the bulk of permafrost literature comes from the science departments concerned with surficial processes (e.g. geomorphology, hydrology, agriculture, etc) and from engineering concerns, such as foundation of constructions and pipeline design. This focus within the permafrost research inevitably yields a biased but also an abundant amount of information on localised surficial processes and a limited amount on regional and deep permafrost characteristics. Possible conclusions are that there is

  13. Surface and subsurface conditions in permafrost areas - a literature review

    Energy Technology Data Exchange (ETDEWEB)

    Vidstrand, Patrik [Bergab, Goeteborg (Sweden)

    2003-02-01

    This report contains a summary of some of the information within existing technical and scientific literature on permafrost. Permafrost is viewed as one of the future climate driven process domains that may exist in Scandinavia, and that may give rise to significantly different surface and subsurface conditions than the present. Except for changes in the biosphere, permafrost may impact hydraulic, mechanical, and chemical subsurface processes and conditions. Permafrost and its influences on the subsurface conditions are thus of interest for the performance and safety assessments of deep geological waste repositories. The definition of permafrost is 'ground that stays at or below 0 deg C for at least two consecutive years'. Permafrost will effect the geological subsurface to some depth. How deep the permafrost may grow is a function of the heat balance, thermal conditions at the surface and within the ground, and the geothermal heat flux from the Earth's inner parts. The main chapters of the report summaries the knowledge on permafrost evolution, occurrence and distribution, and extracts information concerning hydrology and mechanical and chemical impacts due to permafrost related conditions. The results of a literature review are always dependent on the available literature. Concerning permafrost there is some literature available from investigations in the field of long-term repositories and some from mining industries. However, reports of these investigations are few and the bulk of permafrost literature comes from the science departments concerned with surficial processes (e.g. geomorphology, hydrology, agriculture, etc) and from engineering concerns, such as foundation of constructions and pipeline design. This focus within the permafrost research inevitably yields a biased but also an abundant amount of information on localised surficial processes and a limited amount on regional and deep permafrost characteristics. Possible conclusions are that

  14. 30 CFR 912.764 - Process for designating areas unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... surface coal mining operations. 912.764 Section 912.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE IDAHO § 912.764 Process for designating areas unsuitable for surface coal mining... coal mining and reclamation operations. ...

  15. Porosity-dependent fractal nature of the porous silicon surface

    Energy Technology Data Exchange (ETDEWEB)

    Rahmani, N.; Dariani, R. S., E-mail: dariani@alzahra.ac.ir [Department of Physics, Alzahra University, Tehran, 1993893973 (Iran, Islamic Republic of)

    2015-07-15

    Porous silicon films with porosity ranging from 42% to 77% were fabricated by electrochemical anodization under different current density. We used atomic force microscopy and dynamic scaling theory for deriving the surface roughness profile and processing the topography of the porous silicon layers, respectively. We first compared the topography of bare silicon surface with porous silicon and then studied the effect of the porosity of porous silicon films on their scaling behavior by using their self-affinity nature. Our work demonstrated that silicon compared to the porous silicon films has the highest Hurst parameter, indicating that the formation of porous layer due to the anodization etching of silicon surface leads to an increase of its roughness. Fractal analysis revealed that the evolution of the nanocrystallites’ fractal dimension along with porosity. Also, we found that both interface width and Hurst parameter are affected by the increase of porosity.

  16. 30 CFR 941.761 - Areas designated unsuitable for surface coal mining by act of Congress.

    Science.gov (United States)

    2010-07-01

    ... WITHIN EACH STATE SOUTH DAKOTA § 941.761 Areas designated unsuitable for surface coal mining by act of Congress. Part 761 of this chapter, Areas Designated by Act of Congress, shall apply to surface coal mining... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Areas designated unsuitable for surface coal...

  17. 30 CFR 937.761 - Areas designated unsuitable for surface coal mining by Act of Congress.

    Science.gov (United States)

    2010-07-01

    ... WITHIN EACH STATE OREGON § 937.761 Areas designated unsuitable for surface coal mining by Act of Congress. Part 761 of this chapter, Areas Designated by Act of Congress, shall apply to surface coal mining and... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Areas designated unsuitable for surface coal...

  18. 30 CFR 905.761 - Areas designated unsuitable for surface coal mining by act of Congress.

    Science.gov (United States)

    2010-07-01

    ... WITHIN EACH STATE CALIFORNIA § 905.761 Areas designated unsuitable for surface coal mining by act of Congress. Part 761 of this chapter, Areas Designated by Act of Congress, shall apply to surface coal mining... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Areas designated unsuitable for surface coal...

  19. 30 CFR 910.761 - Areas designated unsuitable for surface coal mining by Act of Congress.

    Science.gov (United States)

    2010-07-01

    ... WITHIN EACH STATE GEORGIA § 910.761 Areas designated unsuitable for surface coal mining by Act of Congress. Part 761 of this chapter, Areas Designated by Act of Congress, shall apply to surface coal mining... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Areas designated unsuitable for surface coal...

  20. 30 CFR 903.761 - Areas designated unsuitable for surface coal mining by act of Congress.

    Science.gov (United States)

    2010-07-01

    ... WITHIN EACH STATE ARIZONA § 903.761 Areas designated unsuitable for surface coal mining by act of Congress. Part 761 of this chapter, Areas Designated by Act of Congress, applies to surface coal mining... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Areas designated unsuitable for surface coal...

  1. 30 CFR 939.761 - Areas designated unsuitable for surface coal mining by Act of Congress.

    Science.gov (United States)

    2010-07-01

    ... WITHIN EACH STATE RHODE ISLAND § 939.761 Areas designated unsuitable for surface coal mining by Act of Congress. Part 761 of this chapter, Areas Designated by Act of Congress, shall apply to surface coal mining... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Areas designated unsuitable for surface coal...

  2. 30 CFR 922.761 - Areas designated unsuitable for surface coal mining by act of Congress.

    Science.gov (United States)

    2010-07-01

    ... WITHIN EACH STATE MICHIGAN § 922.761 Areas designated unsuitable for surface coal mining by act of Congress. Part 761 of this chapter, Areas Designated by Act of Congress, shall apply to surface coal mining... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Areas designated unsuitable for surface coal...

  3. 30 CFR 921.761 - Areas designated unsuitable for surface coal mining by Act of Congress.

    Science.gov (United States)

    2010-07-01

    ... WITHIN EACH STATE MASSACHUSETTS § 921.761 Areas designated unsuitable for surface coal mining by Act of Congress. Part 761 of this chapter, Areas Designated by Act of Congress, shall apply to surface coal mining... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Areas designated unsuitable for surface coal...

  4. 30 CFR 912.761 - Areas designated unsuitable for surface coal mining by act of Congress.

    Science.gov (United States)

    2010-07-01

    ... WITHIN EACH STATE IDAHO § 912.761 Areas designated unsuitable for surface coal mining by act of Congress. Part 761 of this chapter, Areas Designated by Act of Congress, shall apply to surface coal mining and... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Areas designated unsuitable for surface coal...

  5. 30 CFR 947.761 - Areas designated unsuitable for surface coal mining by act of Congress.

    Science.gov (United States)

    2010-07-01

    ... WITHIN EACH STATE WASHINGTON § 947.761 Areas designated unsuitable for surface coal mining by act of Congress. Part 761 of this chapter, Areas Designated by Act of Congress, shall apply to surface coal mining... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Areas designated unsuitable for surface coal...

  6. 30 CFR 942.761 - Areas designated unsuitable for surface coal mining by act of Congress.

    Science.gov (United States)

    2010-07-01

    ... WITHIN EACH STATE TENNESSEE § 942.761 Areas designated unsuitable for surface coal mining by act of Congress. Part 761 of this chapter, Areas Designated by Act of Congress, shall apply to surface coal mining... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Areas designated unsuitable for surface coal...

  7. 30 CFR 903.762 - Criteria for designating areas as unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... for surface coal mining operations. 903.762 Section 903.762 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE ARIZONA § 903.762 Criteria for designating areas as unsuitable for surface coal mining operations. Part 762 of this chapter, Criteria for Designating Areas Unsuitable for Surface Coal Mining...

  8. 30 CFR 922.762 - Criteria for designating areas as unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... for surface coal mining operations. 922.762 Section 922.762 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE MICHIGAN § 922.762 Criteria for designating areas as unsuitable for surface coal mining operations. Part 762 of this chapter, Criteria for Designating Areas Unsuitable for Surface Coal Mining...

  9. 30 CFR 937.762 - Criteria for designating areas as unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... for surface coal mining operations. 937.762 Section 937.762 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE OREGON § 937.762 Criteria for designating areas as unsuitable for surface coal mining operations. Part 762 of this chapter, Criteria for Designating Areas Unsuitable for Surface Coal Mining...

  10. 30 CFR 912.762 - Criteria for designating areas as unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... for surface coal mining operations. 912.762 Section 912.762 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE IDAHO § 912.762 Criteria for designating areas as unsuitable for surface coal mining operations. Part 762 of this chapter, Criteria for Designating Areas Unsuitable for Surface Coal Mining...

  11. 30 CFR 910.762 - Criteria for designating areas as unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... for surface coal mining operations. 910.762 Section 910.762 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE GEORGIA § 910.762 Criteria for designating areas as unsuitable for surface coal mining operations. Part 762 of this chapter, Criteria for Designating Areas Unsuitable for Surface Coal Mining...

  12. Effects of raw material texture and activation manner on surface area of porous carbons derived from biomass resources.

    Science.gov (United States)

    Zhang, Feng; Li, Guo-Dong; Chen, Jie-Sheng

    2008-11-01

    Porous carbons have been prepared from biomass resources, such as cornstalks, rice straws, pine needles and pinecone hulls, through a simple carbonization and KOH solution activation process. The pore sizes of the obtained porous carbons are mainly distributed in the range of 1-2 nm, whereas the surface areas of the materials vary from 1000 to more than 3000 m(2) g(-1) depending on the raw materials and preparation conditions. It is found that the biomass texture and the activation manner play key roles in determination of surface areas of the porous carbons. In addition, the amount of activation agent, the activation temperature and the activation time also affect the surface area of the porous carbons but to a less extent. The obtained porous carbons with high surface areas show good performance when used as Pt-catalyst supports for cinanamaldehyde hydrogenation.

  13. Polarimetric Scattering Properties of Landslides in Forested Areas and the Dependence on the Local Incidence Angle

    Directory of Open Access Journals (Sweden)

    Takashi Shibayama

    2015-11-01

    Full Text Available This paper addresses the local incidence angle dependence of several polarimetric indices corresponding to landslides in forested areas. Landslide is deeply related to the loss of human lives and their property. Various kinds of remote sensing techniques, including aerial photography, high-resolution optical satellite imagery, LiDAR and SAR interferometry (InSAR, have been available for landslide investigations. SAR polarimetry is potentially an effective measure to investigate landslides because fully-polarimetric SAR (PolSAR data contain more information compared to conventional single- or dual-polarization SAR data. However, research on landslide recognition utilizing polarimetric SAR (PolSAR is quite limited. Polarimetric properties of landslides have not been examined quantitatively so far. Accordingly, we examined the polarimetric scattering properties of landslides by an assessment of how the decomposed scattering power components and the polarimetric correlation coefficient change with the local incidence angle. In the assessment, PolSAR data acquired from different directions with both spaceborne and airborne SARs were utilized. It was found that the surface scattering power and the polarimetric correlation coefficient of landslides significantly decrease with the local incidence angle, while these indices of surrounding forest do not. This fact leads to establishing a method of effective detection of landslide area by polarimetric information.

  14. Area-dependent impedance-based voltage shifts during tribocorrosion of Ti-6Al-4V biomaterials: theory and experiment

    Science.gov (United States)

    Gilbert, Jeremy L.; Mali, Sachin A.; Liu, Yangping

    2016-09-01

    Tribocorrosion of medical devices causes the electrode potential across the device-solution interface to become more negative. This study provides a theoretical impedance-based understanding of voltage versus time changes that arise. It combines tribocorrosion with the voltage-dependent impedance characteristics of the surface, the relative anodic and cathodic areas and the mechanics and electrochemistry of oxide abrasion. An area-dependent Randle’s circuit is used with the tribocorrosion current equation to show the time-dependent voltage change with disruption and repassivation of the oxide. Heredity integrals are used to predict voltage over time for any arbitrary current-time path. Experiments using titanium pin-on-disk fretting corrosion are used to assess the theoretical model and to demonstrate its behavior.

  15. Kilohertz Electrical Stimulation Nerve Conduction Block: Effects of Electrode Surface Area.

    Science.gov (United States)

    Patel, Yogi A; Kim, Brian S; Rountree, William S; Butera, Robert J

    2017-10-01

    Kilohertz electrical stimulation (KES) induces repeatable and reversible conduction block of nerve activity and is a potential therapeutic option for various diseases and disorders resulting from pathological or undesired neurological activity. However, successful translation of KES nerve block to clinical applications is stymied by many unknowns, such as the relevance of the onset response, acceptable levels of waveform contamination, and optimal electrode characteristics. We investigated the role of electrode geometric surface area on the KES nerve block threshold using 20- and 40-kHz current-controlled sinusoidal KES. Electrodes were electrochemically characterized and used to characterize typical KES waveforms and electrode charge characteristics. KES nerve block amplitudes, onset duration, and recovery of normal conduction after delivery of the KES were evaluated along with power requirements for effective KES nerve block. Results from this investigation demonstrate that increasing electrode geometric surface area provides for a more power-efficient KES nerve block. Reductions in block threshold by increased electrode surface area were found to be KES-frequency-dependent, with block thresholds and average power consumption reduced by greater than two times with 20-kHz KES waveforms and greater than three times for 40-kHz KES waveforms.

  16. The dependence of lipid monolayer lipolysis on surface pressure.

    OpenAIRE

    Hall, D G

    1992-01-01

    Brönsted-Bjerrum theory [Brönsted (1922) Z. Phys. Chem. 102, 169-207; (1925) Z. Phys. Chem. 115, 337-364; Bjerrum (1924) Z. Phys. Chem. 108, 82-100] as applied to reactions at interfaces is used to interpret published data on the lipolysis of dinonanoyl phosphatidylcholine monolayers by pancreatic phospholipase A2. Reasonable quantitative agreement between theoretical and experimental results occurs when the reported effects of surface pressure on the amount of adsorbed enzyme are used togeth...

  17. Microscopic Investigation of Reversible Nanoscale Surface Size Dependent Protein Conjugation

    Directory of Open Access Journals (Sweden)

    Michael A. Carpenter

    2009-05-01

    Full Text Available Aβ1-40 coated 20 nm gold colloidal nanoparticles exhibit a reversible color change as pH is externally altered between pH 4 and 10. This reversible process may contain important information on the initial reversible step reported for the fibrillogenesis of Aβ (a hallmark of Alzheimer’s disease. We examined this reversible color change by microscopic investigations. AFM images on graphite surfaces revealed the morphology of Aβ aggregates with gold colloids. TEM images clearly demonstrate the correspondence between spectroscopic features and conformational changes of the gold colloid.

  18. The Tangent Conoids Family Which Depends on the Ruled Surface

    OpenAIRE

    Özyılmaz, E.

    1998-01-01

    In this study, a new congruence[A••] has been definedby putting a tangent right conoid on each line of a ruled surface (A1(s)) of a line congruence [A]. Then, by considering special case of the congruence [A••] which has been defined in the previous part, the concepts of tangent congruence, drall and the relation among Blaschke vectors of Blaschke trihedrons, having common line Ao has been examined for this special case. At the end of this study, the concept of tangent congruence for some spe...

  19. Effect of impervious surface area and vegetation changes on mean ...

    African Journals Online (AJOL)

    adeniyi adeyemi

    sprawl and this has contributed to increase in surface temperature. Keyword: Thematic indices, surface temperature, Landsat, vegetation, ISA, Tshwane Metropolis. 1. Introduction. Globally, rapid increase in population in major cities has led to urban sprawl at an unprecedented rate which is, according to the analysis and ...

  20. Field dependent surface resistance of niobium on copper cavities

    Directory of Open Access Journals (Sweden)

    T. Junginger

    2015-07-01

    Full Text Available The surface resistance R_{S} of superconducting cavities prepared by sputter coating a niobium film on a copper substrate increases significantly stronger with the applied rf field compared to cavities of bulk material. A possible cause is that the thermal boundary resistance between the copper substrate and the niobium film induces heating of the inner cavity wall, resulting in a higher R_{S}. Introducing helium gas in the cavity, and measuring its pressure as a function of applied field allowed to conclude that the inner surface of the cavity is heated up by less than 120 mK when R_{S} increases with E_{acc} by 100  nΩ. This is more than one order of magnitude less than what one would expect from global heating. Additionally, the effects of cooldown speed and low temperature baking have been investigated in the framework of these experiments. It is shown that for the current state of the art niobium on copper cavities there is only a detrimental effect of low temperature baking. A fast cooldown results in a lowered R_{S}.

  1. Dissolution Effects on Specific Surface Area, Particle Size, and Porosity of Pentelic Marble.

    Science.gov (United States)

    Orkoula, Malvina G.; Koutsoukos, Petros G.

    2001-07-15

    Dissolution of natural stone such as marble is not limited to its surface. The porous structure, known to play an important role in stone decay, is also affected by the conditions of dissolution. In the present work, the changes in pore size distribution of Pentelic marble particles accompanying chemical dissolution in undersaturated solutions and at alkaline pH 8.25 were investigated. The specific surface area and the mesopore distribution of the Pentelic marble tested showed a pronounced decrease to very low values. On the other hand, the sizes of macropores exhibited a tendency to increase with the extent of dissolution due either to dissolution in the interior of the pores or to fusion of small pores into larger. Furthermore, the number of small particles decreased significantly, reaching complete disappearance, depending on the extent of dissolution. At the same time, the relative number of particles of intermediate size increased. Copyright 2001 Academic Press.

  2. Adsorption of neon and tetrafluoromethane on carbon nanohorn aggregates: differences in specific surface area values

    Science.gov (United States)

    Krungleviciute, Vaiva; Yudasaka, Masako; Iijima, Sumio; Migone, Aldo

    2008-03-01

    We have measured adsorption isotherms for two different adsorbates, neon and tetrafluoromethane, on dahlia-like carbon nanohorn aggregates. The experiments were performed at similar relative temperatures for both gases. The measurements were conducted to explore the effect of adsorbate diameter on the behavior of the resulting adsorbed systems. We measured the effective specific surface area value of the nanohorn sample using both gases, and we found that this quantity was about 22% smaller when we determined this quantity using tetrafluoromethane, the larger molecule. Isosteric heat and binding energy values were also determined from our measurements. We will compare our experimental results with those from a computer simulation study performed by Prof. M. Calbi. The simulations help us understand the source of the observed differences in the measured specific surface values, as well as the coverage dependence of the isosteric heat of adsorption for both gases.

  3. Changes in the Surface Area of Glaciers in Northern Eurasia

    Science.gov (United States)

    Khromova, T.; Nosenko, G.

    2012-12-01

    Glaciers are widely recognized as key indicators of climate change. Recent evidence suggests an acceleration of glacier mass loss in several key mountain regions. Glacier recession implies the landscape changes in the glacial zone, origin of new lakes and activation of natural disaster processes, catastrophic mudflows, ice avalanches, outburst floods, and etc. The presence of glaciers in itself threats to human life, economic activity and growing infrastructure. Economical and recreational human activity in mountain regions requires relevant information on snow and ice objects. Absence or inadequacy of such information results in financial and human losses. A more comprehensive evaluation of glacier changes is imperative to assess ice contributions to global sea level rise and the future of water resources from glacial basins. One of the urgent steps is a full inventory of all ice bodies, their volume and changes The first estimation of glaciers state and glaciers distribution in the big part of Northern Eurasia has been done in the USSR Glacier Inventory published in 1966 -1980 as a part of IHD activity. The Inventory is based on topographic maps and air photos and reflects the status of the glaciers in 1957-1970y. There is information about 23796 glaciers with area of 78222.3 km2 in the Inventory. It covers 23 glacier systems on Northern Eurasia. In the 80th the USSR Glacier Inventory has been transformed in the digital form as a part of the World Glacier Inventory. Recent satellite data provide a unique opportunity to look again at these glaciers and to evaluate changes in glacier extent for the second part of XX century. In the paper we report about 15 000 glaciers outlines for Caucasus, Pamir, Tien-Shan, Altai, Syntar-Khayata, Cherskogo Range, Kamchatka and Russian Arctic which have been derived from ASTER and Landsat imagery and could be used for glacier changes evaluation. The results show that glaciers are retreating in all these regions. There is, however

  4. AFM-based tribological study of nanopatterned surfaces: the influence of contact area instabilities.

    Science.gov (United States)

    Rota, A; Serpini, E; Gazzadi, G C; Valeri, S

    2016-04-06

    Although the importance of morphology on the tribological properties of surfaces has long been proved, an exhaustive understanding of nanopatterning effects is still lacking due to the difficulty in both fabricating 'really nano-' structures and detecting their tribological properties. In the present work we show how the probe-surface contact area can be a critical parameter due to its remarkable local variability, making a correct interpretation of the data very difficult in the case of extremely small nanofeatures. Regular arrays of parallel 1D straight nanoprotrusions were fabricated by means of a low-dose focused ion beam, taking advantage of the amorphization-related swelling effect. The tribological properties of the patterns were detected in the presence of air and in vacuum (dry ambient) by atomic force microscopy. We have introduced a novel procedure and data analysis to reduce the uncertainties related to contact instabilities. The real time estimation of the radius of curvature of the contacting asperity enables us to study the dependence of the tribological properties of the patterns from their geometrical characteristics. The effect of the patterns on both adhesion and the coefficient of friction strongly depends on the contact area, which is linked to the local radius of curvature of the probe. However, a detectable hydrophobic character induced on the hydrophilic native SiO2 has been observed as well. The results suggest a scenario for capillary formation on the patterns.

  5. SMAPVEX12 Surface Roughness Data for Agricultural Area V001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains surface roughness data collected at several agricultural sites as a part of the Soil Moisture Active Passive Validation Experiment 2012...

  6. Size-dependent surface plasmon resonance in silver silica nanocomposites

    International Nuclear Information System (INIS)

    Thomas, Senoy; Nair, Saritha K; Jamal, E Muhammad Abdul; Anantharaman, M R; Al-Harthi, S H; Varma, Manoj Raama

    2008-01-01

    Silver silica nanocomposites were obtained by the sol-gel technique using tetraethyl orthosilicate (TEOS) and silver nitrate (AgNO 3 ) as precursors. The silver nitrate concentration was varied for obtaining composites with different nanoparticle sizes. The structural and microstructural properties were determined by x-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). X-ray photoelectron spectroscopic (XPS) studies were done for determining the chemical states of silver in the silica matrix. For the lowest AgNO 3 concentration, monodispersed and spherical Ag crystallites, with an average diameter of 5 nm, were obtained. Grain growth and an increase in size distribution was observed for higher concentrations. The occurrence of surface plasmon resonance (SPR) bands and their evolution in the size range 5-10 nm is studied. For decreasing nanoparticle size, a redshift and broadening of the plasmon-related absorption peak was observed. The observed redshift and broadening of the SPR band was explained using modified Mie scattering theory

  7. High-surface-area silica nanospheres (KCC-1) with a fibrous morphology

    KAUST Repository

    Polshettiwar, Vivek

    2010-08-02

    Fibrous nanosilica: A new family of high-surface-area silica nanospheres (KCC-1) have been prepared (see picture). KCC-1 features excellent physical properties, including high surface area, unprecedented fibrous surface morphology, high thermal (up to 950 °C) and hydrothermal stabilities, and high mechanical stability. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Investigating the time-dependent zeta potential of wood surfaces.

    Science.gov (United States)

    Muff, Livius F; Luxbacher, Thomas; Burgert, Ingo; Michen, Benjamin

    2018-05-15

    This work reports on streaming potential measurements through natural capillaries in wood and investigates the cause of a time-dependent zeta potential measured during the equilibration of wood cell-walls with an electrolyte solution. For the biomaterial, this equilibration phase takes several hours, which is much longer than for many other materials that have been characterized by electrokinetic measurements. During this equilibration phase the zeta potential magnitude is decaying due to two parallel mechanisms: (i) the swelling of the cell-wall which causes a dimensional change reducing the charge density at the capillary interface; (ii) the transport of ions from the electrolyte solution into the permeable cell-wall which alters the electrical potential at the interface by internal charge compensation. The obtained results demonstrate the importance of equilibration kinetics for an accurate determination of the zeta potential, especially for materials that interact strongly with the measurement electrolyte. Moreover, the change in zeta potential with time can be correlated with the bulk swelling of wood if the effect of electrolyte ion diffusion is excluded. This study shows the potential of streaming potential measurements of wood, and possibly of other hygroscopic and nanoporous materials, to reveal kinetic information about their interaction with liquids, such as swelling and ion uptake. Copyright © 2018 Elsevier Inc. All rights reserved.

  9. Lung deposited surface area concentrations in a street canyon

    Science.gov (United States)

    Kuuluvainen, Heino; Hietikko, Riina; Järvinen, Anssi; Saukko, Erkka; Irjala, Matti; Niemi, Jarkko V.; Timonen, Hilkka; Keskinen, Jorma; Rönkkö, Topi

    2017-04-01

    Street canyons are interesting environments with respect to the dispersion of traffic emissions and human exposure. Pedestrians may be exposed to relatively high concentrations of fine particles and the vertical dispersion affects the human exposure above the ground level in buildings. Previously, particle concentrations have been measured in street canyons at a few different heights (Marini et al., 2015). The information on the lung deposited surface area (LDSA) concentration, which is a relevant metric for the negative health effects, is very limited even at the ground level of street canyons (Kuuluvainen et al., 2016). More information especially on the vertical dispersion and the ground level concentrations is needed, for instance, for the use of urban planning and the design of ventilation systems in buildings. Measurements were carried out in a busy street canyon in Helsinki, Finland, at an urban super-site measurement station (Mäkelänkatu 50). The data included vertical concentration profiles measured in an intensive measurement campaign with a Partector (Naneos GmbH) installed into a drone, long-term measurements with an AQ Urban particle sensor (Pegasor Ltd.), and an extensive comparison measurement in the field with different devices measuring the LDSA. These devices were an AQ Urban, Partector, DiSCmini (Testo AG), NSAM (TSI Inc.), and an ELPI+ (Dekati Ltd.). In addition, continuous measurements of gas phase components, particle size distributions, and meteorology were run at the supersite. The vertical profile measurements were con-ducted in November 2016 during two days. In the measurements, the drone was flown from the ground level to an altitude of 50 or 100 m, which is clearly above the roof level of the buildings. Altogether, 48 up-and-down flights were conducted during the two days. The vertical profiles were supported by continuous measurements at the ground level on both sides of the street canyon. The long-term measurements were conducted

  10. Temperature dependence of luminescence for different surface flaws in high purity silica glass

    International Nuclear Information System (INIS)

    Fournier, J.; Grua, P.; Neauport, J.; Fargin, E.; Jubera, V.; Talaga, D.; Del Guerzo, A.; Raffy, G.; Jouannigot, S.

    2013-01-01

    In situ temperature dependence of the Photoluminescence under 325 nm irradiation is used to investigate defect populations existing in different surface flaws in high purity fused silica. Five photoluminescence bands peaking at 1.9, 2.1, 2.3, 2.63 and 3.11 eV have been detected in the spectral area ranging from 1.6 up to 3.6 eV. The Gaussian deconvolution of spectra allows dividing the five luminescence bands in two categories. The former corresponds to bands showing a significant intensity enhancement while temperature decreases; the latter corresponds to bands remaining insensitive to the temperature evolution. Such a behavior brings new information on defects involved in laser damage mechanism at 351 nm in nanosecond regime. (authors)

  11. Military Surface Grid Areas: Atlantic / Gulf of Mexico

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A regular pattern of polygons that represent arbitrary delineations of an Operating Area (OPAREA). The MarineCadastre.gov team worked with the Navy to provide this...

  12. 30 CFR 910.764 - Process for designating areas unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... surface coal mining operations. 910.764 Section 910.764 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE GEORGIA § 910.764 Process for designating areas unsuitable for surface coal mining...

  13. 30 CFR 937.764 - Process for designating areas unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... surface coal mining operations. 937.764 Section 937.764 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE OREGON § 937.764 Process for designating areas unsuitable for surface coal mining...

  14. 30 CFR 947.762 - Criteria for designating areas as unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... for surface coal mining operations. 947.762 Section 947.762 Mineral Resources OFFICE OF SURFACE MINING... mining operations. Part 762 of this chapter, Criteria for Designating Areas Unsuitable for Surface Coal Mining Operations, shall apply to surface coal mining and reclamation operations. ...

  15. 30 CFR 921.762 - Criteria for designating areas as unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... for surface coal mining operations. 921.762 Section 921.762 Mineral Resources OFFICE OF SURFACE MINING... mining operations. Part 762 of this chapter, Criteria for Designating Areas Unsuitable for Surface Coal Mining Operations, shall apply to surface coal mine operations. ...

  16. 30 CFR 922.764 - Process for designating areas unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... surface coal mining operations. 922.764 Section 922.764 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE MICHIGAN § 922.764 Process for designating areas unsuitable for surface coal mining...

  17. 30 CFR 942.764 - Process for designating areas unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... surface coal mining operations. 942.764 Section 942.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE TENNESSEE § 942.764 Process for designating areas unsuitable for surface coal mining... Mining Operations, shall apply to surface coal mining and reclamation operations. (b) The Secretary shall...

  18. 30 CFR 941.764 - Process for designating areas unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... surface coal mining operations. 941.764 Section 941.764 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE SOUTH DAKOTA § 941.764 Process for designating areas unsuitable for surface coal mining...

  19. 30 CFR 941.762 - Criteria for designating areas as unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... for surface coal mining operations. 941.762 Section 941.762 Mineral Resources OFFICE OF SURFACE MINING... mining operations. Part 762 of this chapter, Criteria for Designating Areas Unsuitable for Surface Coal Mining Operations, shall apply to surface coal mine operations. ...

  20. 30 CFR 939.764 - Process for designating areas unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... surface coal mining operations. 939.764 Section 939.764 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE RHODE ISLAND § 939.764 Process for designating areas unsuitable for surface coal mining...

  1. 30 CFR 933.762 - Criteria for designating areas as unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... for surface coal mining operations. 933.762 Section 933.762 Mineral Resources OFFICE OF SURFACE MINING... mining operations. Part 762 of this chapter, Criteria for Designation Areas Unsuitable for Surface Coal Mining Operations, shall apply to surface coal mining and reclamation operations. ...

  2. 30 CFR 939.762 - Criteria for designating areas as unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... for surface coal mining operations. 939.762 Section 939.762 Mineral Resources OFFICE OF SURFACE MINING... mining operations. Part 762 of this chapter, Criteria for Designating Areas Unsuitable for Surface Coal Mining Operations, shall apply to surface coal mining and reclamation operations. ...

  3. 30 CFR 905.762 - Criteria for designating areas as unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... for surface coal mining operations. 905.762 Section 905.762 Mineral Resources OFFICE OF SURFACE MINING... mining operations. Part 762 of this chapter, Criteria for Designating Areas Unsuitable for Surface Coal Mining Operations, shall apply to surface coal mining operations. ...

  4. Surface albedo measurements in Mexico City metropolitan area

    Energy Technology Data Exchange (ETDEWEB)

    Castro, T; Mar, B; Longoria, R; Ruiz Suarez, L. G [Centro de Ciencias de la Atmosfera, UNAM, Mexico, D.F. (Mexico); Morales, L [Instituto de Geografia, UNAM, Mexico, D.F. (Mexico)

    2001-04-01

    Optical and thermal properties of soils are important input data for the meteorological and photochemical modules of air quality models. As development of these models increase on spatial resolution good albedo data become more important. In this paper measurements of surface albedo of UV (295-385 nm) and visible (450-550 nm) radiation are reported for different urban and rural surfaces in the vicinity of Mexico City. It was found for the downtown zone and average albedo value of 0.05 which is in very good agreement with reported values for urban surfaces. Our albedo values measured in UV region for grey cement and green grass are of 0.10 and 0.009, respectively, and quite similar to those found at the literature of 0.11 and 0.008 for those type of surfaces. [Spanish] Las propiedades opticas y termicas de suelos son datos importantes para los modulos meteorologicos y fotoquimicos de los modelos de calidad del aire. Conforme aumenta la resolucion espacial del modelo se vuelve mas importante contar con buenos datos de albedo. En este articulo se presentan mediciones de albedo superficial de radiacion Ultravioleta (295-385 nm) y visible (450-550 nm) para diferentes superficies urbanas. Los valores medidos de albedo en la region UV para cemento gris y pasto verde son de 0.10 y 0.009, respectivamente, y son muy similares a los reportados en la literatura, 0.11 y 0.008 para este tipo de superficies.

  5. Large Area Diamond Tribological Surfaces with Negligible Wear in Extreme Environments, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In Phase I we propose to demonstrate the processing of very large area diamond sliding bearings and tribological surfaces. The bearings and surfaces will experience...

  6. The Effect of Specific Surface Area of Chitin-Metal Silicate Coprocessed Excipient on the Chemical Decomposition of Cefotaxime Sodium.

    Science.gov (United States)

    Al-Nimry, Suhair S; Alkhamis, Khouloud A; Alzarieni, Kawthar Z

    2017-02-01

    Chitin-metal silicates are multifunctional excipients used in tablets. Previously, a correlation between the surface acidity of chitin-calcium and chitin-magnesium silicate and the chemical decomposition of cefotaxime sodium was found but not with chitin-aluminum silicate. This lack of correlation could be due to the catalytic effect of silica alumina or the difference in surface area of the excipients. The objective of this study was to investigate the effect of the specific surface area of the excipient on the chemical decomposition of cefotaxime sodium in the solid state. Chitin was purified and coprocessed with different metal silicates to prepare the excipients. The specific surface area was determined using gas adsorption. The chemical decomposition was studied at constant temperature and relative humidity. Also, the degradation in solution was studied. A correlation was found between the degradation rate constant and the surface area of chitin-aluminum and chitin-calcium silicate but not with chitin-magnesium silicate. This was due to the small average pore diameter of this excipient. Also, the degradation in solution was slower than in solid state. In conclusion, the stability of cefotaxime sodium was dependent on the surface area of the excipient in contact with the drug. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  7. Surface adhesion and its dependence on surface roughness and humidity measured with a flat AFM tip

    NARCIS (Netherlands)

    Colak, A.; Wormeester, Herbert; Zandvliet, Henricus J.W.; Poelsema, Bene

    2012-01-01

    The adhesion force between a surface and the tip of an atomic force microscope cantilever has been determined by recording force–distance curves with an atomic force microscope. Flat tips with a diameter of 2 μm were used to mimic the adhesion between two parallel surfaces. In such a configuration,

  8. Assessment of mercury erosion by surface water in Wanshan mercury mining area.

    Science.gov (United States)

    Dai, ZhiHui; Feng, Xinbin; Zhang, Chao; Shang, Lihai; Qiu, Guangle

    2013-08-01

    Soil erosion is a main cause of land degradation, and in its accelerated form is also one of the most serious ecological environmental problems. Moreover, there are few studies on migration of mercury (Hg) induced by soil erosion in seriously Hg-polluted districts. This paper selected Wanshan Hg mining area, SW China as the study area. Revised universal soil loss equation (RUSLE) and Geographic information system (GIS) methods were applied to calculate soil and Hg erosion and to classify soil erosion intensity. Our results show that the soil erosion rate can reach up to 600,884tkm(-2)yr(-1). Surfaces associated with very slight and extremely severe erosion include 76.6% of the entire land in Wanshan. Furthermore, the cumulative erosion rates in the area impacted by extremely severe erosion make up 90.5% of the total. On an annual basis, Hg surface erosion load was predicted to be 505kgyr(-1) and the corresponding mean migration flux of Hg was estimated to be 3.02kgkm(-2)yr(-1). The erosion loads of Hg resulting from farmland and meadow soil were 175 and 319kgyr(-1) respectively, which were enhanced compared to other landscape types due to the fact that they are generally located in the steep zones associated with significant reclamation. Contributing to establish a mass balance of Hg in Wanshan Hg mining area, this study supplies a dependable scientific basis for controlling soil and water erosion in the local ecosystems. Land use change is the most effective way for reducing Hg erosion load in Wanshan mining area. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. Pressure-dependent surface viscosity and its surprising consequences in interfacial lubrication flows

    Science.gov (United States)

    Manikantan, Harishankar; Squires, Todd M.

    2017-02-01

    The surface shear rheology of many insoluble surfactants depends strongly on the surface pressure (or concentration) of that surfactant. Here we highlight the dramatic consequences that surface-pressure-dependent surface viscosities have on interfacially dominant flows, by considering lubrication-style geometries within high Boussinesq (Bo) number flows. As with three-dimensional lubrication, high-Bo surfactant flows through thin gaps give high surface pressures, which in turn increase the local surface viscosity, further amplifying lubrication stresses and surface pressures. Despite their strong nonlinearity, the governing equations are separable, so that results from two-dimensional Newtonian lubrication analyses may be immediately adapted to treat surfactant monolayers with a general functional form of ηs(Π ) . Three paradigmatic systems are analyzed to reveal qualitatively new features: a maximum, self-limiting value for surfactant fluxes and particle migration velocities appears for Π -thickening surfactants, and kinematic reversibility is broken for the journal bearing and for suspensions more generally.

  10. Possibilities of surface waters monitoring at mining areas using UAV

    Science.gov (United States)

    Lisiecka, Ewa; Motyka, Barbara; Motyka, Zbigniew; Pierzchała, Łukasz; Szade, Adam

    2018-04-01

    The selected, remote measurement methods are discussed, useful for determining surface water properties using mobile unmanned aerial platforms (UAV). The possibilities of using this type of solutions in the scope of measuring spatial, physicochemical and biological parameters of both natural and anthropogenic water reservoirs, including flood polders, water-filled pits, settling tanks and mining sinks were analyzed. Methods of remote identification of the process of overgrowing this type of ecosystems with water and coastal plant formations have also been proposed.

  11. The Effect of 200 MPa Pressure on Specific Surface Area of Clay

    Directory of Open Access Journals (Sweden)

    Koszela-Marek Ewa

    2015-02-01

    Full Text Available The paper presents the results of laboratory studies of the 200 MPa pressure effect on specific surface area of clay. The original high-pressure investigation stand was used for the pressure tests. Determination of the specific surface area was performed by the methylene blue adsorption method. The results of the specific surface area test were compared for non-pressurized clays and for clays pressured in a high-pressure chamber. It was found that the specific surface area of pressurized soil clearly increased. This shows that some microstructural changes take place in the soil skeleton of clays.

  12. Assessment of large aperture scintillometry for large-area surface ...

    Indian Academy of Sciences (India)

    29

    This study defines that large aperture scintillometer is robust instrument which can evaluate energy flux over a large area with a long term series time domain. Moreover, further studied should be conducted to use in crop simulation modelling, developing of new model with calibration and validation of remote sensing energy ...

  13. Natural Resource Dependency and Decentralized Conservation Within Kanchenjunga Conservation Area Project, Nepal

    Science.gov (United States)

    Parker, Pete; Thapa, Brijesh

    2012-02-01

    Kanchenjunga Conservation Area Project (KCAP) in Nepal is among the first protected areas in the world to institute a completely decentralized system of conservation and development. Proponents of decentralized conservation claim that it increases management efficiency, enhances the responsiveness to local needs, and promotes greater equity among local residents. This study assessed local equity by evaluating the levels of dependencies on natural resources among households and the factors affecting that dependency. Data were collected via detailed surveys among 205 randomly selected households within the KCAP. Natural resource dependency was evaluated by comparing the ratio of total household income to income derived from access to natural resources. Economic, social, and access-related variables were employed to determine potential significant predictors of dependency. Overall, households were heavily dependent on natural resources for their income, especially households at higher elevations and those with more adult members. The households that received remittances were most able to supplement their income and, therefore, drastically reduced their reliance on the access to natural resources. Socio-economic variables, such as land holdings, education, caste, and ethnicity, failed to predict dependency. Household participation in KCAP-sponsored training programs also failed to affect household dependency; however, fewer than 20% of the households had any form of direct contact with KCAP personnel within the past year. The success of the KCAP as a decentralized conservation program is contingent on project capacity-building via social mobilization, training programs, and participatory inclusion in decision making to help alleviate the dependency on natural resources.

  14. Tuning Porosity and Surface Area in Mesoporous Silicon for Application in Li-Ion Battery Electrodes.

    Science.gov (United States)

    Cook, John B; Kim, Hyung-Seok; Lin, Terri C; Robbennolt, Shauna; Detsi, Eric; Dunn, Bruce S; Tolbert, Sarah H

    2017-06-07

    This work aims to improve the poor cycle lifetime of silicon-based anodes for Li-ion batteries by tuning microstructural parameters such as pore size, pore volume, and specific surface area in chemically synthesized mesoporous silicon. Here we have specifically produced two different mesoporous silicon samples from the magnesiothermic reduction of ordered mesoporous silica in either argon or forming gas. In situ X-ray diffraction studies indicate that samples made in Ar proceed through a Mg 2 Si intermediate, and this results in samples with larger pores (diameter ≈ 90 nm), modest total porosity (34%), and modest specific surface area (50 m 2 g -1 ). Reduction in forming gas, by contrast, results in direct conversion of silica to silicon, and this produces samples with smaller pores (diameter ≈ 40 nm), higher porosity (41%), and a larger specific surface area (70 m 2 g -1 ). The material with smaller pores outperforms the one with larger pores, delivering a capacity of 1121 mAh g -1 at 10 A g -1 and retains 1292 mAh g -1 at 5 A g -1 after 500 cycles. For comparison, the sample with larger pores delivers a capacity of 731 mAh g -1 at 10 A g -1 and retains 845 mAh g -1 at 5 A g -1 after 500 cycles. The dependence of capacity retention and charge storage kinetics on the nanoscale architecture clearly suggests that these microstructural parameters significantly impact the performance of mesoporous alloy type anodes. Our work is therefore expected to contribute to the design and synthesis of optimal mesoporous architectures for advanced Li-ion battery anodes.

  15. Tritium in Precipitation, Surface and Groundwaters in the Zagreb Area

    International Nuclear Information System (INIS)

    Horvatincic, N.; Baresic, J.; Sironic, A.; Krajcar Bronic, I.; Obelic, B.

    2011-01-01

    Radioactive isotope tritium (3H) and stable isotopes of hydrogen (2H/1H) and oxygen (18O/16O) were measured in Sava River, precipitation and groundwater at 3 monitoring wells (piezometers) and 1 production well of the Petrusevec aquifer, close to the Sava River. Samples were collected monthly during 2010. The investigation is included in the Regional IAEA Project RER/8/016 Using Environmental Isotopes for Evaluation of Streamwater/Groundwater Interactions in Selected Aquifers in the Danube Basin. Sava River is a tributary of Danube River and the aim of the investigation is to determine the influence of surface stream of Sava River to the groundwater of aquifer used for water exploitation. In this work only 3H results were presented. 3H was measured by liquid scintillation counter Quantulus 1220, using electrolytic enrichment for all samples. 3H activity in precipitation showed slight seasonal fluctuation between 4 TU and 14 TU, with higher values in summer. 3H activity of Sava River and groundwater of the Petrusevec aquifer followed 3H of precipitation till May 2010. Significant increase of 3H in Sava River was observed in June, (199 @ 20) TU, and in the next month it fell down at 6 TU. Increase of 3H was also observed in groundwater but with damped response (maximum 60 TU) and with delay of 2 - 3 months related to Sava River. Different response of different piezometers and the well indicated the different infiltration times of surface water of Sava River to groundwater of the Petrusevec aquifer. The increased 3H activity in surface and groundwaters was caused by release of tritiated water from the Krsko Nuclear Power Plant, 30 km upstream from Zagreb. The results of 3H, 2H/1H and 18O/16O measurements will be used to determine the infiltration time of groundwater of the Petrusevec aquifer using conceptual and mathematical models. (author)

  16. Chloride ion-dependent surface-enhanced Raman scattering study of biotin on the silver surface

    International Nuclear Information System (INIS)

    Liu Fangfang; Gu Huaimin; Yuan Xiaojuan; Dong Xiao; Lin Yue

    2011-01-01

    In the present paper, the surface enhanced Raman scattering (SERS) technique was employed to study the SERS spectra of biotin molecules formed on the silver surface. The adsorption geometries of biotin molecules on the silver surface were analyzed based on the SERS data. It can be found that most vibration modes show a Raman shift in silver sol after the addition of sodium chloride solution. In addition, The Raman signals of biotin become weaker and weaker with the increase of the concentration of sodium chloride. This may be due to that the interaction between chloride ions and silver particles is stronger than the interaction between biotin molecules and silver particles. When the concentration of sodium chloride in silver colloid is higher than 0.05mol/L, superfluous chloride ions may form an absorption layer so that biotin can not be adsorbed on silver surface directly. The changes in intensity and profile shape in the SERS spectra suggest different adsorption behavior and surface-coverage of biotin on silver surface. The SERS spectra of biotin suggest that the contribution of the charge transfer mechanism to SERS may be dominant.

  17. Density-dependent changes in effective area occupied for sea-bottom-associated marine fishes

    DEFF Research Database (Denmark)

    Thorson, James T.; Rindorf, Anna; Gao, Jin

    2016-01-01

    The spatial distribution of marine fishes can change for many reasons, including density-dependent distributional shifts. Previous studies show mixed support for either the proportional-density model (PDM; no relationship between abundance and area occupied, supported by ideal-free distribution...... marine regions, to determine whether the BM or PDM provides a better description for sea-bottom-associated fishes. We fit a spatio-temporal model and estimate changes in effective area occupied and abundance, and combine results to estimate the average abundance–area relationship as well as variability......-third of combinations (34.6%) are predicted to increase in area more than 1% for every 10% increase in abundance. We therefore infer that population density generally changes faster than effective area occupied during abundance changes. Gadiformes have the strongest estimated relationship (average 1.0% area increase...

  18. Adsorption of naphthalene onto a high-surface-area carbon from waste ion exchange resin.

    Science.gov (United States)

    Shi, Qianqian; Li, Aimin; Zhu, Zhaolian; Liu, Bing

    2013-01-01

    A high-surface-area carbon (KC-1) was prepared from waste polystyrene-based ion exchange resin by KOH activation and used for naphthalene adsorption. The carbon exhibited a good hydrophobic nature with developed porous structure, favoring the adsorption of organic compounds. The Brunauer-Emmett-Teller surface area and total pore volume of KC-1 were 3442.2 and 1.68 cm3/g, respectively, which can be compared with those of KOH-activated carbons prepared from other precursors. Batch experiments were carried out to investigate the adsorption of naphthalene onto KC-1. The equilibrium data were analyzed by the Langmuir, Freundlich, and Polanyi-Manes isotherms and agreed with the Polanyi-Manes Model. The adsorption of naphthalene depended greatly on the porosity of the carbon, and the dispersive interactions between naphthalene and carbon could be relatively weak. The pH variation in aqueous solution had little effect on the adsorption process. The equilibrium time for 0.04 g/L of carbon dose was around 5 hr. Different models were used to evaluate the kinetic data and the pseudo second-order model was suitable to describe the kinetic process of naphthalene adsorption onto KC-1. Regeneration of spent carbon could be carried out effectively by alcohol treatment. The results indicated that KC-1 was a promising adsorbent for the removal of polycyclic aromatic hydrocarbons from aqueous solutions.

  19. Temperature dependence of immunoreactions using shear horizontal surface acoustic wave immunosensors

    Science.gov (United States)

    Kogai, Takashi; Yatsuda, Hiromi; Kondoh, Jun

    2017-07-01

    In this paper, the temperature dependence of immunoreactions, which are antibody-antigen reactions, on a shear horizontal surface acoustic wave (SH-SAW) immunosensor is described. The immunosensor is based on a reflection-type delay line on a 36° Y-cut 90° X-propagation quartz substrate, where the delay line is composed of a floating electrode unidirectional transducer (FEUDT), a grating reflector, and a sensing area between them. In order to evaluate the temperature dependence of immunoreactions, human serum albumin (HSA) antigen-antibody reactions are investigated. The SH-SAW immunosensor chip is placed in a thermostatic chamber and the changes in the SH-SAW velocity resulting from the immunoreactions are measured at different temperatures. As a result, it is observed that the HSA immunoreactions are influenced by the ambient temperature and that higher temperatures provide more active reactions. In order to analyze the immunoreactions, an analytical approach using an exponential fitting method for changes in SH-SAW velocity is employed.

  20. Large area optical mapping of surface contact angle.

    Science.gov (United States)

    Dutra, Guilherme; Canning, John; Padden, Whayne; Martelli, Cicero; Dligatch, Svetlana

    2017-09-04

    Top-down contact angle measurements have been validated and confirmed to be as good if not more reliable than side-based measurements. A range of samples, including industrially relevant materials for roofing and printing, has been compared. Using the top-down approach, mapping in both 1-D and 2-D has been demonstrated. The method was applied to study the change in contact angle as a function of change in silver (Ag) nanoparticle size controlled by thermal evaporation. Large area mapping reveals good uniformity for commercial Aspen paper coated with black laser printer ink. A demonstration of the forensic and chemical analysis potential in 2-D is shown by uncovering the hidden CsF initials made with mineral oil on the coated Aspen paper. The method promises to revolutionize nanoscale characterization and industrial monitoring as well as chemical analyses by allowing rapid contact angle measurements over large areas or large numbers of samples in ways and times that have not been possible before.

  1. FreeSASA: An open source C library for solvent accessible surface area calculations.

    Science.gov (United States)

    Mitternacht, Simon

    2016-01-01

    Calculating solvent accessible surface areas (SASA) is a run-of-the-mill calculation in structural biology. Although there are many programs available for this calculation, there are no free-standing, open-source tools designed for easy tool-chain integration. FreeSASA is an open source C library for SASA calculations that provides both command-line and Python interfaces in addition to its C API. The library implements both Lee and Richards' and Shrake and Rupley's approximations, and is highly configurable to allow the user to control molecular parameters, accuracy and output granularity. It only depends on standard C libraries and should therefore be easy to compile and install on any platform. The library is well-documented, stable and efficient. The command-line interface can easily replace closed source legacy programs, with comparable or better accuracy and speed, and with some added functionality.

  2. Data on the role of accessible surface area on osmolytes-induced protein stabilization

    Directory of Open Access Journals (Sweden)

    Safikur Rahman

    2017-02-01

    Full Text Available This paper describes data related to the research article “Testing the dependence of stabilizing effect of osmolytes on the fractional increase in the accessible surface area on thermal and chemical denaturations of proteins” [1]. Heat- and guanidinium chloride (GdmCl-induced denaturation of three disulfide free proteins (bovine cytochrome c (b-cyt-c, myoglobin (Mb and barstar in the presence of different concentrations of methylamines (sarcosine, glycine-betaine (GB and trimethylamine-N-oxide (TMAO was monitored by [ϴ]222, the mean residue ellipticity at 222 nm at pH 7.0. Methylamines belong to a class of osmolytes known to protect proteins from deleterious effect of urea. This paper includes comprehensive thermodynamic data obtained from the heat- and GdmCl-induced denaturations of barstar, b-cyt-c and Mb.

  3. BLM National Surface Management Agency: Area Polygons, Withdrawal Area Polygons, and Special Public Purpose Withdrawal Area Polygons

    Data.gov (United States)

    Federal Geographic Data Committee — The SMA implementation is comprised of one feature dataset, with several polygon feature classes, rather than a single feature class. SurfaceManagementAgency: The...

  4. Cyclic Brunn-Minkowski Inequalities for p -affine surface area | Zhao ...

    African Journals Online (AJOL)

    In 2010, Werner and Ye extended the denition for mixed p-affine surface area to all real numbers p. Following this, we establish some isoperimetric inequalities for the general mixed p-affine surface area. The results in special cases yield some of the recent results on inequalities of this type. Mathematics Subject ...

  5. 30 CFR 933.761 - Areas designated unsuitable for surface coal mining by Act of Congress.

    Science.gov (United States)

    2010-07-01

    ... WITHIN EACH STATE NORTH CAROLINA § 933.761 Areas designated unsuitable for surface coal mining by Act of Congress. Part 761 of this chapter, Areas Designated Unsuitable for Coal Mining by Act of Congress, with the exception of §§ 761.11(c) and 761.12(f)(1), shall apply to surface coal mining and reclamation...

  6. Groundwater–surface water interactions, vegetation dependencies and implications for water resources management in the semi-arid Hailiutu River catchment, China – a synthesis

    NARCIS (Netherlands)

    Zhou, Y.; Wenninger, J.; Yang, Z.; Yin, L.; Huang, J.; Hou, L.; Wang, X.; Zhang, D.; Uhlenbrook, S.

    2013-01-01

    During the last decades, large-scale land use changes took place in the Hailiutu River catchment, a semi-arid area in northwest China. These changes had significant impacts on the water resources in the area. Insights into groundwater and surface water interactions and vegetation-water dependencies

  7. Target surface area effects on hot electron dynamics from high intensity laser-plasma interactions

    Science.gov (United States)

    Zulick, C.; Raymond, A.; McKelvey, A.; Chvykov, V.; Maksimchuk, A.; Thomas, A. G. R.; Willingale, L.; Yanovsky, V.; Krushelnick, K.

    2016-06-01

    Reduced surface area targets were studied using an ultra-high intensity femtosecond laser in order to determine the effect of electron sheath field confinement on electron dynamics. X-ray emission due to energetic electrons was imaged using a {K}α imaging crystal. Electrons were observed to travel along the surface of wire targets, and were slowed mainly by the induced fields. Targets with reduced surface areas were correlated with increased hot electron densities and proton energies. Hybrid Vlasov-Fokker-Planck simulations demonstrated increased electric sheath field strength in reduced surface area targets.

  8. 30 CFR 905.764 - Process for designating areas unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... surface coal mining operations. 905.764 Section 905.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE CALIFORNIA § 905.764 Process for designating areas unsuitable for surface coal mining... coal mining operations beginning one year after the effective date of this program. ...

  9. 30 CFR 947.764 - Process for designating areas unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... surface coal mining operations. 947.764 Section 947.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE WASHINGTON § 947.764 Process for designating areas unsuitable for surface coal mining... coal mining and reclamation operations. (b) The Secretary shall notify the Washington Department of...

  10. 30 CFR 903.764 - Process for designating areas unsuitable for surface coal mining operations.

    Science.gov (United States)

    2010-07-01

    ... surface coal mining operations. 903.764 Section 903.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE ARIZONA § 903.764 Process for designating areas unsuitable for surface coal mining... coal mining operations beginning June 24, 1996, one year after the effective date of this program. ...

  11. Siloxanes removal from biogas by high surface area adsorbents.

    Science.gov (United States)

    Gislon, P; Galli, S; Monteleone, G

    2013-12-01

    Biogas utilized for energy production needs to be free from organic silicon compounds, as their burning has damaging effects on turbines and engines; organic silicon compounds in the form of siloxanes can be found in biogas produced from urban wastes, due to their massive industrial use in synthetic product, such as cosmetics, detergents and paints. Siloxanes removal from biogas can be carried out by various methods (Mona, 2009; Ajhar et al., 2010 May; Schweigkofler and Niessner, 2001); aim of the present work is to find a single practical and economic way to drastically and simultaneously reduce both the hydrogen sulphide and the siloxanes concentration to less than 1 ppm. Some commercial activated carbons previously selected (Monteleone et al., 2011) as being effective in hydrogen sulfide up taking have been tested in an adsorption measurement apparatus, by flowing the most volatile siloxane (hexamethyldisiloxane or L2) in a nitrogen stream, typically 100-200 ppm L2 over N2, through an activated carbon powder bed; the adsorption process was analyzed by varying some experimental parameters (concentration, grain size, bed height). The best activated carbon shows an adsorption capacity of 0.1g L2 per gram of carbon. The next thermogravimetric analysis (TGA) confirms the capacity data obtained experimentally by the breakthrough curve tests. The capacity results depend on L2 concentration. A regenerative carbon process is then carried out by heating the carbon bed up to 200 °C and flushing out the adsorbed L2 samples in a nitrogen stream in a three step heating procedure up to 200 °C. The adsorption capacity is observed to degrade after cycling the samples through several adsorption-desorption cycles. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Surface Area, and Oxidation Effects on Nitridation Kinetics of Silicon Powder Compacts

    Science.gov (United States)

    Bhatt, R. T.; Palczer, A. R.

    1998-01-01

    Commercially available silicon powders were wet-attrition-milled from 2 to 48 hr to achieve surface areas (SA's) ranging from 1.3 to 70 sq m/g. The surface area effects on the nitridation kinetics of silicon powder compacts were determined at 1250 or 1350 C for 4 hr. In addition, the influence of nitridation environment, and preoxidation on nitridation kinetics of a silicon powder of high surface area (approximately equals 63 sq m/g) was investigated. As the surface area increased, so did the percentage nitridation after 4 hr in N2 at 1250 or 1350 C. Silicon powders of high surface area (greater than 40 sq m/g) can be nitrided to greater than 70% at 1250 C in 4 hr. The nitridation kinetics of the high-surface-area powder compacts were significantly delayed by preoxidation treatment. Conversely, the nitridation environment had no significant influence on the nitridation kinetics of the same powder. Impurities present in the starting powder, and those accumulated during attrition milling, appeared to react with the silica layer on the surface of silicon particles to form a molten silicate layer, which provided a path for rapid diffusion of nitrogen and enhanced the nitridation kinetics of high surface area silicon powder.

  13. Surface dependent behaviour of CdS LO-phonon mode

    International Nuclear Information System (INIS)

    Molina-Contreras, J R; Medina-Gutierrez, C; Frausto-Reyes, C; Trejo-Vazquez, R; Villalobos-Pina, F J; Romo-Luevano, G; Calixto, S

    2007-01-01

    In this paper, we develop a sensitive optical method to monitor the surface roughness in the investigation of surfaces. By applying this method to measure the RMS surface roughness of various surfaces, we found RMS values which are comparable to those obtained by atomic force microscopy measurements. In addition, we present a simple empirical model to calculate the RMS surface roughness which shows very good agreement with the surface roughness measurements taken by the method reported in this paper. Finally, the application of our method to the study of the LO-phonon mode of CdS suggests that its intensity is dominated by the surface roughness. This roughness dependent behaviour of the CdS LO-phonon mode is experimentally confirmed by using an excitation wavelength near its E 0 transition

  14. Surface dependent behaviour of CdS LO-phonon mode

    Energy Technology Data Exchange (ETDEWEB)

    Molina-Contreras, J R [Departamento de IngenierIa Electrica y Electronica, Instituto Tecnologico de Aguascalientes, Av. Lopez Mateos 1081 Oriente, Fracc. Bonna Gens, CP 20256. Aguascalientes, Ags. (Mexico); Medina-Gutierrez, C [Universidad de Guadalajara, Centro Universitario de los Lagos, Av. Enrique DIaz de Leon s/n, Fracc. Paseos de la Montana, CP 47460, Lagos de Moreno, Jal. (Mexico); Frausto-Reyes, C [Centro de Investigaciones en Optica AC, Unidad Aguascalientes, Prolong., Constitucion 607, Fracc. Reserva Loma Bonita, CP 20200, Apartado Postal 507, Ags. (Mexico); Trejo-Vazquez, R [Departamento de IngenierIa Electrica y Electronica, Instituto Tecnologico de Aguascalientes, Av. Lopez Mateos 1081 Oriente, Fracc. Bonna Gens, CP 20256. Aguascalientes, Ags. (Mexico); Villalobos-Pina, F J [Departamento de IngenierIa Electrica y Electronica, Instituto Tecnologico de Aguascalientes, Av. Lopez Mateos 1081 Oriente, Fracc. Bonna Gens, CP 20256. Aguascalientes, Ags. (Mexico); Romo-Luevano, G [Intel TecnologIa de Mexico, SA de CV, Systems Research Center-Mexico, Parque Industrial Tecnologico II, Periferico Sur 7980, edificio 4-E, 45600 Tlaquepaque, Jalisco (Mexico); Calixto, S [Centro de Investigaciones en Optica, AC, Loma del Bosque 115, Colonia Lomas del Campestre, CP 37150 Leon, Guanajuato (Mexico)

    2007-08-21

    In this paper, we develop a sensitive optical method to monitor the surface roughness in the investigation of surfaces. By applying this method to measure the RMS surface roughness of various surfaces, we found RMS values which are comparable to those obtained by atomic force microscopy measurements. In addition, we present a simple empirical model to calculate the RMS surface roughness which shows very good agreement with the surface roughness measurements taken by the method reported in this paper. Finally, the application of our method to the study of the LO-phonon mode of CdS suggests that its intensity is dominated by the surface roughness. This roughness dependent behaviour of the CdS LO-phonon mode is experimentally confirmed by using an excitation wavelength near its E{sub 0} transition.

  15. On geometry-dependent vortex stability and topological spin excitations on curved surfaces with cylindrical symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho-Santos, V.L., E-mail: vagson.santos@bonfim.ifbaiano.edu.br [Instituto Federal de Educação, Ciência e Tecnologia Baiano – Senhor do Bonfim, 48970-000 Senhor do Bonfim, Bahia (Brazil); Apolonio, F.A. [Departamento de Física, Universidade Federal de Viçosa, 36570-000 Viçosa, Minas Gerais (Brazil); Oliveira-Neto, N.M. [Departamento de Química e Exatas, Universidade Estadual do Sudoeste da Bahia, 45206-190 Jequié, Bahia (Brazil)

    2013-08-01

    We study the Heisenberg model on cylindrically symmetric curved surfaces. Two kinds of excitations are considered. The first is given by the isotropic regime, yielding the sine-Gordon equation and π solitons are predicted. The second one is given by the XY model, leading to a vortex turning around the surface. Helical states are also considered, however, topological arguments cannot be used to ensure its stability. The energy and the anisotropy parameter which stabilizes the vortex state are explicitly calculated for two surfaces: catenoid and hyperboloid. The results show that the anisotropy and the vortex energy depends on the underlying geometry. -- Highlights: •Applying the anisotropic Heisenberg model on curved surfaces. •Appearance of topological solitons on curved surfaces with cylindrical symmetry. •Calculus of the vortex energy, which depends on curvature. •Discussion on features of non-topological helical-like states. •Vortex stability ensured by the anisotropy parameter value.

  16. Environmental and geochemical assessment of surface sediments on irshansk ilmenite deposit area

    Directory of Open Access Journals (Sweden)

    Наталия Олеговна Крюченко

    2015-03-01

    Full Text Available It is revealed the problem of pollution of surface sediments of Irshansk ilmenite deposit area of various chemical elements hazard class (Mn, V, Ba, Ni, Co, Cr, Mo, Cu, Pb, Zn. It is determined its average content in surface sediments of various functional areas (forest and agricultural land, flood deposits, reclaimed land, calculated geochemical criteria, so given ecological and geochemical assessment of area

  17. Hot-electron-assisted femtochemistry at surfaces: A time-dependent density functional theory approach

    DEFF Research Database (Denmark)

    Gavnholt, Jeppe; Rubio, Angel; Olsen, Thomas

    2009-01-01

    Using time-evolution time-dependent density functional theory (TDDFT) within the adiabatic local-density approximation, we study the interactions between single electrons and molecular resonances at surfaces. Our system is a nitrogen molecule adsorbed on a ruthenium surface. The surface is modeled...... at two levels of approximation, first as a simple external potential and later as a 20-atom cluster. We perform a number of calculations on an electron hitting the adsorbed molecule from inside the surface and establish a picture, where the resonance is being probed by the hot electron. This enables us...

  18. Incident energy dependence of scattering behavior of water molecules on Si (100) and graphite surfaces

    Science.gov (United States)

    Kihara, G.; Kotsubo, Y.; Yoshimoto, Y.; Kinefuchi, I.; Takagi, S.

    2016-11-01

    The interaction between water molecules and solid surfaces has a great impact on water vapor flows in nanostructures. We conduct molecular beam scattering experiments covering the incident energy range corresponding to the thermal energy at room temperature to investigate the scattering behavior of water molecules on silicon and graphite surfaces. The incident energy dependence of the scattering distributions exhibits opposite trends on these surfaces. Molecular dynamics simulations reveal that the difference is caused by the inertia effect of the incident molecules and the surface corrugations.

  19. On the relationship between enamel band complexity and occlusal surface area in Equids (Mammalia, Perissodactyla

    Directory of Open Access Journals (Sweden)

    Nicholas A. Famoso

    2016-07-01

    Full Text Available Enamel patterns on the occlusal surfaces of equid teeth are asserted to have tribal-level differences. The most notable example compares the Equini and Hipparionini, where Equini have higher crowned teeth with less enamel-band complexity and less total occlusal enamel than Hipparionini. Whereas previous work has successfully quantified differences in enamel band shape by dividing the length of enamel band by the square root of the occlusal surface area (Occlusal Enamel Index, OEI, it was clear that OEI only partially removes the effect of body size. Because enamel band length scales allometrically, body size still has an influence on OEI, with larger individuals having relatively longer enamel bands than smaller individuals. Fractal dimensionality (D can be scaled to any level, so we have used it to quantify occlusal enamel complexity in a way that allows us to get at an accurate representation of the relationship between complexity and body size. To test the hypothesis of tribal-level complexity differences between Equini and Hipparionini, we digitally traced a sample of 98 teeth, one tooth per individual; 31 Hipparionini and 67 Equini. We restricted our sampling to the P3-M2 to reduce the effect of tooth position. After calculating the D of these teeth with the fractal box method which uses the number of boxes of various sizes to calculate the D of a line, we performed a t-test on the individual values of D for each specimen, comparing the means between the two tribes, and a phylogenetically informed generalized least squares regression (PGLS for each tribe with occlusal surface area as the independent variable and D as the dependent variable. The slopes of both PGLS analyses were compared using a t-test to determine if the same linear relationship existed between the two tribes. The t-test between tribes was significant (p < 0.0001, suggesting different D populations for each lineage. The PGLS for Hipparionini was a positive but not

  20. Description of climate, surface hydrology, and near-surface hydrogeology. Preliminary site description. Forsmark area - version 1.2

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, Per-Olof [Artesia Grundvattenkonsult AB, Stockholm (Sweden); Werner, Kent [SWECO VIAK AB/Golder Associates AB, Stockholm (Sweden); Bosson, Emma; Berglund, Sten [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden); Juston, John [DBE Sweden, Uppsala (Sweden)

    2005-06-15

    conductive zones shown to exist in the upper bedrock. The sediment stratigraphy of lakes and wetlands is crucial for their function as discharge areas for groundwater. Low-permeable sediments will restrict the discharge and result in a relocation of the discharge to areas where such sediments are missing. Concerning the interactions between surface water and groundwater, it may also be noted that comparisons between measured lake water levels and groundwater levels below and around lakes indicate that the lakes in some cases may act as sources of groundwater recharge. Specifically, observations from Lake Bolundsfjaerden and Lake Eckarfjaerden show that such conditions were at hand during the dry summer of 2003. However, whether the observed water level relations correspond to significant water fluxes depends also on the hydrogeological properties of the lake sediments and the underlying Quaternary deposits. 'Old' water with high chloride content has been found below Lake Bolundsfjaerden, Lake Eckarfjaerden and Lake Gaellsbotraesket. These observations can either be interpreted as the result of a continuous discharge of deep water, or as evidence of more or less stagnant water below the lakes. Furthermore, the relations between the sea water level and the water levels in Lake Norra Bassaengen, Lake Bolundsfjaerden and Lake Lillfjaerden show that inflow of sea water can occur during periods of high sea water levels. The results from the hydrological GIS modelling support the assumptions and conclusions in the descriptive model. The flow model is highly sensitive to the topography, as this is the only parameter determining the flow pattern. Consequently, the simulated locations of recharge and discharge areas are strongly influenced by the local topography. In addition, the flat topography implies that small errors in the topographical model (the Digital Elevation Model, DEM) may have large effects on the modelled flow pattern. Ditches, diverted water courses and

  1. Development of cortical thickness and surface area in autism spectrum disorder

    Directory of Open Access Journals (Sweden)

    Vincent T. Mensen

    2017-01-01

    Full Text Available Autism spectrum disorder (ASD is a neurodevelopmental disorder often associated with changes in cortical volume. The constituents of cortical volume – cortical thickness and surface area – have separable developmental trajectories and are related to different neurobiological processes. However, little is known about the developmental trajectories of cortical thickness and surface area in ASD. In this magnetic resonance imaging (MRI study, we used an accelerated longitudinal design to investigate the cortical development in 90 individuals with ASD and 90 typically developing controls, aged 9 to 20 years. We quantified cortical measures using the FreeSurfer software package, and then used linear mixed model analyses to estimate the developmental trajectories for each cortical measure. Our primary finding was that the development of surface area follows a linear trajectory in ASD that differs from typically developing controls. In typical development, we found a decline in cortical surface area between the ages of 9 and 20 that was absent in ASD. We found this pattern in all regions where developmental trajectories for surface area differed between groups. When we applied a more stringent correction that takes the interdependency of measures into account, this effect on cortical surface area retained significance for left banks of superior temporal sulcus, postcentral area, and right supramarginal area. These areas have previously been implicated in ASD and are involved in the interpretation and processing of audiovisual social stimuli and distinction between self and others. Although some differences in cortical volume and thickness were found, none survived the more stringent correction for multiple testing. This study underscores the importance of distinguishing between cortical surface area and thickness in investigating cortical development, and suggests the development of cortical surface area is of importance to ASD.

  2. Specific surface area of a crushed welded tuff before and after aqueous dissolution

    Science.gov (United States)

    Reddy, M.M.; Claassen, H.C.

    1994-01-01

    Specific surface areas were measured for several reference minerals (anorthoclase, labradorite and augite), welded tuff and stream sediments from Snowshoe Mountain, near Creede, Colorado. Crushed and sieved tuff had an unexpectedly small variation in specific surface area over a range of size fractions. Replicate surface area measurements of the largest and smallest tuff particle size fractions examined (1-0.3 mm and <0.212 mm) were 2.3 ?? 0.2 m2/g for each size fraction. Reference minerals prepared in the same way as the tuff had smaller specific surface areas than that of the tuff of the same size fraction. Higher than expected tuff specific surface areas appear to be due to porous matrix. Tuff, reacted in solutions with pH values from 2 to 6, had little change in specific surface area in comparison with unreacted tuff. Tuff, reacted with solutions having high acid concentrations (0.1 M hydrochloric acid or sulfuric-hydrofluoric acid), exhibited a marked increase in specific surface area compared to unreacted tuff. ?? 1994.

  3. Impact of Surface Soil Moisture Variations on Radar Altimetry Echoes at Ku and Ka Bands in Semi-Arid Areas

    Directory of Open Access Journals (Sweden)

    Christophe Fatras

    2018-04-01

    Full Text Available Radar altimetry provides information on the topography of the Earth surface. It is commonly used for the monitoring not only sea surface height but also ice sheets topography and inland water levels. The radar altimetry backscattering coefficient, which depends on surface roughness and water content, can be related to surface properties such as surface soil moisture content. In this study, the influence of surface soil moisture on the radar altimetry echo and backscattering coefficient is analyzed over semi-arid areas. A semi-empirical model of the soil’s complex dielectric permittivity that takes into account that small-scale roughness and large-scale topography was developed to simulate the radar echoes. It was validated using waveforms acquired at Ku and Ka-bands by ENVISAT RA-2 and SARAL AltiKa respectively over several sites in Mali. Correlation coefficients ranging from 0.66 to 0.94 at Ku-band and from 0.27 to 0.96 at Ka-band were found. The increase in surface soil moisture from 0.02 to 0.4 (i.e., the typical range of variations in semi-arid areas increase the backscattering from 10 to 15 dB between the core of the dry and the maximum of the rainy seasons.

  4. Study of the mobility, surface area, and sintering behavior of agglomerates in the transition regime by tandem differential mobility analysis

    International Nuclear Information System (INIS)

    Cho, Kuk; Hogan, Christopher J.; Biswas, Pratim

    2007-01-01

    The surface area of nanosized agglomerates is of great importance as the reactivity and health effects of such particles are highly dependent on surface area. Changes in surface area through sintering during nanoparticle synthesis processes are also of interest for precision control of synthesised particles. Unfortunately, information on particle surface area and surface area dynamics is not readily obtainable through traditional particle mobility sizing techniques. In this study, we have experimentally determined the mobility diameter of transition regime agglomerates with 3, 4, and 5 primary particles. Agglomerates were produced by spray drying well-characterised polystyrene latex particles with diameters of 55, 67, 76, and 99 nm. Tandem differential mobility analysis was used to determine agglomerate mobility diameter by selecting monodisperse agglomerates with the same number of primary particles in the first DMA, and subsequently completely sintering the agglomerates in a furnace aerosol reactor. The size distribution of the completely sintered particles was measured by an SMPS system, which allowed for the determination of the number of primary particles in the agglomerates. A simple power law regression was used to express mobility diameter as a function of primary particle size and the number of primary particles, and had an excellent correlation (R 2 = 0.9971) with the experimental data. A scaling exponent was determined from the experimental data to relate measured mobility diameter to surface area for agglomerates. Using this relationship, the sintering characteristics of agglomerates were also examined for varying furnace temperatures and residence times. The sintering data agreed well with the geometric sintering model (GSM) model proposed by Cho and Biswas (2006a) as well as with the model proposed Koch and Friedlander (1990) for sintering by viscous flow

  5. Surface morphology of polyethylene glycol films produced by matrix-assisted pulsed laser evaporation (MAPLE): Dependence on substrate temperature

    DEFF Research Database (Denmark)

    Rodrigo, K.; Czuba, P.; Toftmann, B.

    2006-01-01

    The dependence of the surface morphology on the substrate temperature during film deposition was investigated for polyethylene glycol (PEG) films by matrix-assisted pulsed laser evaporation (MAPLE). The surface structure was studied with a combined technique of optical imaging and AFM measurements....... There was a clear difference between the films produced below and above the melting point of PEG. For temperatures above the melting point, the polymer material was distributed non-uniformly over the substrate with growths areas, where cluster-like structures merge into large islands of micrometer size....... At these temperatures, the islands in the investigated growth areas cover most of the bottom layer which has a typical height of 50-150 nm. (c) 2005 Elsevier B.V. All rights reserved....

  6. Strain-Dependent Solid Surface Stress and the Stiffness of Soft Contacts

    Science.gov (United States)

    Jensen, Katharine E.; Style, Robert W.; Xu, Qin; Dufresne, Eric R.

    2017-10-01

    Surface stresses have recently emerged as a key player in the mechanics of highly compliant solids. The classic theories of contact mechanics describe adhesion with a compliant substrate as a competition between surface energies driving deformation to establish contact and bulk elasticity resisting this. However, it has recently been shown that surface stresses provide an additional restoring force that can compete with and even dominate over elasticity in highly compliant materials, especially when length scales are small compared to the ratio of the surface stress to the elastic modulus, ϒ /E . Here, we investigate experimentally the contribution of surface stresses to the total force of adhesion. We find that the elastic and capillary contributions to the adhesive force are of similar magnitude and that both are required to account for measured adhesive forces between rigid silica spheres and compliant, silicone gels. Notably, the strain dependence of the solid surface stress contributes to the stiffness of soft solid contacts at leading order.

  7. Effect of specific surface area of MWCNTS on surface roughness and delamination in drilling Epoxy/Glass Fabric Composite

    Science.gov (United States)

    Ponnuvel, S.; Ananth, M. Prem

    2018-03-01

    In this study the effect of specific surface area of the MWCNTs on the drilled hole qualities was investigated. Epoxy araldite LY556 with hardener HY951 and E-glass coarse plain weave fabric are used for the fabrication of reference material (specimen A). Multi-WalledCarbon Nanotubes (MWCNTs) with diameters fabrication of study materials, namely specimen B and specimen C respectively. In specimen B the epoxy resin was filled with MWCNTs having a specific surface area >500 m2 g‑1. MWCNTs in specimen C had a specific surface area >110 m2 g‑1. Drilling experiments were conducted on all the three specimens. Two dimensional delamination factor and the surface roughness of the inner wall of the drilled holes were investigated using Grey Relational Analysis (GRA) and Analysis of variance (ANOVA). Two dimensional delamination factor showed better performance from specimen B and specimen C in comparison with specimen A suggesting improvement in the bonding between epoxy and the glass fiber in the presence of MWCNTs. Similar observations were made for surface roughness of the inner wall of the drilled holes at 1250 rpm. Whereas the presence of MWCNTs (Specimen B and specimen C) produced poor surface finish at 500 rpm in comparison with specimen A. Variations in the hole quality characteristics between specimen B and specimen C was marginal with better observations in specimen C.

  8. Large-area electromagnetic enhancement by a resonant excitation of surface waves on a metallic surface with periodic subwavelength patterns.

    Science.gov (United States)

    Zhang, Xin; Liu, Haitao; Zhong, Ying

    2013-10-07

    We theoretically investigate the electromagnetic enhancement on a metallic surface patterned with periodic subwavelength structures. Fully-vectorial calculations show a large-area electromagnetic enhancement (LAEE) on the surface, which strongly contrasts with the previously reported "hot spots" that occur in specific tiny regions and which relieves the rigorous requirement of the nano-scale location of sample molecules. The LAEE allows for designing more practicable substrates for many enhanced-spectra applications. By building up microscopic models, the LAEE is shown due to a resonant excitation of surface waves that include both the surface plasmon polariton (SPP) and a quasi-cylindrical wave (QCW). The surface waves propagate on the substrate over a long distance and thus greatly enlarge the area of electromagnetic enhancement compared to the nano-sized hot spots caused by localized modes. Gain medium is introduced to further strengthen the large-area surface-wave resonance, with which an enhancement factor (EF) of electric-field intensity up to a few thousands is achieved.

  9. A preformulation evaluation of a photosensitive surface active compound, explaining concentration dependent degradation.

    Science.gov (United States)

    Sigfridsson, Kalle; Carlsson, Karin E

    2017-11-15

    A candidate drug within the cardiovascular area was identified during early research and evaluated for further development. The aim was to understand and explain the degradation mechanisms for the present compound. The stability of the active pharmaceutical ingredient (API) in solution and solid state was studied during different conditions. The bulk compound was exposed to elevated temperatures, increased relative humidity and stressed light conditions. Degradation of the drug in solutions was followed in the presence versus absence of ethylenediaminetetraacetic acid (EDTA), during aerobic versus anaerobic conditions, stored protected from light versus exposed to light and as a function of pH and concentration. It was possible to improve the stability by adding EDTA and completely abolish degradation by storing dissolved compound at anaerobic conditions. Solutions of API were stable between pH3 and 7, with some degradation at pH1, when stored protected from light and at 22°C, but degrade rapidly when exposed to ambient light conditions. The degradation products were identified by mass spectroscopy. Degradation schemes were drawn. There was concentration dependence in the degradation of dissolved drug when exposed to light, showing a titration behavior that concurred with the measured critical micelle/aggregation concentration (CMC/CAC) of the compound. The compound was stable in solution during the investigated time period, at concentrations above CMC/CAC, where the molecule was protected from photodegradation when the compound aggregated. Below CMC/CAC, a significant degradation of the API occurred. This may be a potential explanation why other surface active compounds show concentration dependent degradation. The photosensitivity was also observed for the neutral compound in crystalline and amorphous form, as well as for the crystalline chloride salt of the drug. However, the degradation of amorphous form was faster compared to crystalline material. No

  10. Irreversible particle motion in surfactant-laden interfaces due to pressure-dependent surface viscosity

    Science.gov (United States)

    Manikantan, Harishankar; Squires, Todd M.

    2017-09-01

    The surface shear viscosity of an insoluble surfactant monolayer often depends strongly on its surface pressure. Here, we show that a particle moving within a bounded monolayer breaks the kinematic reversibility of low-Reynolds-number flows. The Lorentz reciprocal theorem allows such irreversibilities to be computed without solving the full nonlinear equations, giving the leading-order contribution of surface pressure-dependent surface viscosity. In particular, we show that a disc translating or rotating near an interfacial boundary experiences a force in the direction perpendicular to that boundary. In unbounded monolayers, coupled modes of motion can also lead to non-intuitive trajectories, which we illustrate using an interfacial analogue of the Magnus effect. This perturbative approach can be extended to more complex geometries, and to two-dimensional suspensions more generally.

  11. Obtaining time-dependent multi-dimensional dividing surfaces using Lagrangian descriptors

    Science.gov (United States)

    Feldmaier, Matthias; Junginger, Andrej; Main, Jörg; Wunner, Günter; Hernandez, Rigoberto

    2017-11-01

    Dynamics between reactants and products are often mediated by a rate-determining barrier and an associated dividing surface leading to the transition state theory rate. This framework is challenged when the barrier is time-dependent because its motion can give rise to recrossings across the fixed dividing surface. A non-recrossing time-dependent dividing surface can nevertheless be attached to the TS trajectory resulting in recrossing-free dynamics. We extend the formalism-constructed using Lagrangian Descriptors-to systems with additional bath degrees of freedom. The propagation of reactant ensembles provides a numerical demonstration that our dividing surface is recrossing-free and leads to exact TST rates.

  12. Temperature-dependent surface density of alkylthiol monolayers on gold nanocrystals

    Science.gov (United States)

    Liu, Xuepeng; Lu, Pin; Zhai, Hua; Wu, Yucheng

    2018-03-01

    Atomistic molecular dynamics (MD) simulations are performed to study the surface density of passivating monolayers of alkylthiol chains on gold nanocrystals at temperatures ranging from 1 to 800 K. The results show that the surface density of alkylthiol monolayer reaches a maximum value at near room temperature (200-300 K), while significantly decreases with increasing temperature in the higher temperature region (> 300 {{K}}), and slightly decreases with decreasing temperature at low temperature (< 200 {{K}}). We find that the temperature dependence of surface ligand density in the higher temperature region is attributed to the substantial ligand desorption induced by the thermal fluctuation, while that at low temperature results from the reduction in entropy caused by the change in the ordering of passivating monolayer. These results are expected helpful to understand the temperature-dependent surface coverage of gold nanocrystals.

  13. Large area window on vacuum chamber surface for neutron scattering instruments

    International Nuclear Information System (INIS)

    Itoh, Shinichi; Yokoo, Tetsuya; Ueno, Kenji; Suzuki, Junichi; Teraoku, Takuji; Tsuchiya, Masao

    2012-01-01

    The feasibility of a large area window using a thin aluminum plate on the surface of the vacuum chamber for neutron scattering instruments at a pulsed neutron source was investigated. In the prototype investigation for a window with an area of 1m×1.4m and a thickness of 1 mm, the measured pressure dependence of the displacement agreed well with a calculation using a nonlinear strain–stress curve up to the plastic deformation region. In addition, we confirmed the repetition test up to 2000 pressurization-and-release cycles, which is sufficient for the lifetime of the vacuum chamber for neutron scattering instruments. Based on these investigations, an actual model of the window to be mounted on the vacuum chamber of the High Resolution Chopper Spectrometer (HRC) at J-PARC was designed. By using a calculated stress distribution on the window, the clamping structure capable of balancing the tension in the window was determined. In a model with a structure identical to the actual window, we confirmed the repetition test over more than 7000 pressurization-and-release cycles, which shows a lifetime long enough for the actual usage of the vacuum chamber on the HRC.

  14. The tunneling magnetoresistance current dependence on cross sectional area, angle and temperature

    Directory of Open Access Journals (Sweden)

    Z. H. Zhang

    2015-03-01

    Full Text Available The magnetoresistance of a MgO-based magnetic tunnel junction (MTJ was studied experimentally. The magnetoresistance as a function of current was measured systematically on MTJs for various MgO cross sectional areas and at various temperatures from 7.5 to 290.1 K. The resistance current dependence of the MTJ was also measured for different angles between the two ferromagnetic layers. By considering particle and angular momentum conservation of transport electrons, the current dependence of magnetoresistance can be explained by the changing of spin polarization in the free magnetic layer of the MTJ. The changing of spin polarization is related to the magnetoresistance, its angular dependence and the threshold current where TMR ratio equals zero. A phenomenological model is used which avoid the complicated barrier details and also describes the data.

  15. Rapid fabrication of large-area, corrosion-resistant superhydrophobic Mg alloy surfaces.

    Science.gov (United States)

    Xu, Wenji; Song, Jinlong; Sun, Jing; Lu, Yao; Yu, Ziyuan

    2011-11-01

    A superhydrophobic magnesium (Mg) alloy surface was successfully fabricated via a facile electrochemical machining process, and subsequently covered with a fluoroalkylsilane (FAS) film. The surface morphologies and chemical compositions were investigated using a scanning electron microscope (SEM) equipped with an energy-dispersive spectroscopy (EDS) and a Fourier-transform infrared spectrophotometer (FTIR). The results show hierarchal rough structures and an FAS film with a low surface energy on the Mg alloy surfaces, which confers good superhydrophobicity with a water contact angle of 165.2° and a water tilting angle of approximately 2°. The processing conditions, such as the processing time and removal rate per unit area at a constant removal mass per unit area, were investigated to determine their effects on the superhydrophobicity. Interestingly, when the removal mass per unit area is constant at approximately 11.10 mg/cm(2), the superhydrophobicity does not change with the removal rate per unit area. Therefore, a superhydrophobic Mg alloy surface can be rapidly fabricated based on this property. A large-area superhydrophobic Mg alloy surface was also fabricated for the first time using a small-area moving cathode. The corrosion resistance and durability of the superhydrophobic surfaces were also examined.

  16. Relationship between Mineral Soil Surface Area and the Biological Degradation of Biosolids Added to Soil

    Directory of Open Access Journals (Sweden)

    Dongqi Wen

    2015-12-01

    Full Text Available Geochemical and biological processes that operate in the soil matrix and on the soil surface are important to the degradation of biosolids in soil. Due to the large surface area of soils it is assumed that the microbial ecology is associated with mineral soil surface area. The total mineral surface areas were determined for soils from eight different fields selected from a long term study (1972–2006 of annual biosolids application to 41 fields in central Illinois varying in size from 3.6 to 66 ha. The surface areas for the soils varied from 1 to 9 m2/g of soil. The biological degradation rates for the eight soils were determined using a biological degradation rate model (DRM and varied from 0.02 to 0.20/year−1. Regression analysis revealed that the degradation rate was positively associated with mineral soil surface area (1 m2/g produces 0.018 year−1 increase in the degradation rate. The annual soil sequestration rate was calculated to increase from 1% to 6% when the soil total surface area increased from 1 to 9 m2/g of soil. Therefore, land application of biosolids is an effective way to enhance carbon sequestration in soils and reduce greenhouse gas emissions.

  17. Cell-surface metalloprotease ADAM12 is internalized by a clathrin- and Grb2-dependent mechanism

    DEFF Research Database (Denmark)

    Hansen, Dorte Stautz; Leyme, Anthony; Grandal, Michael Vibo

    2012-01-01

    ADAM12 (A Disintegrin And Metalloprotease 12), a member of the ADAMs family of transmembrane proteins, is involved in ectodomain shedding, cell-adhesion and signaling, with important implications in cancer. Therefore, mechanisms that regulate the levels and activity of ADAM12 at the cell...... that regulates ADAM cell surface levels and show that ADAM12 internalization involves the clathrin-dependent pathway and Grb2.......-surface are possibly crucial in these contexts. We here investigated internalization and subsequent recycling or degradation of ADAM12 as a potentially important regulatory mechanism. Our results show that ADAM12 is constitutively internalized primarily via the clathrin-dependent pathway and is subsequently detected...

  18. Temperature Dependence of Arn + Cluster Backscattering from Polymer Surfaces: a New Method to Determine the Surface Glass Transition Temperature

    Science.gov (United States)

    Poleunis, Claude; Cristaudo, Vanina; Delcorte, Arnaud

    2018-01-01

    In this work, time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to study the intensity variations of the backscattered Arn + clusters as a function of temperature for several amorphous polymer surfaces (polyolefins, polystyrene, and polymethyl methacrylate). For all these investigated polymers, our results show a transition of the ratio Ar2 +/(Ar2 + + Ar3 +) when the temperature is scanned from -120 °C to +125 °C (the exact limits depend on the studied polymer). This transition generally spans over a few tens of degrees and the temperature of the inflection point of each curve is always lower than the bulk glass transition temperature (Tg) reported for the considered polymer. Due to the surface sensitivity of the cluster backscattering process (several nanometers), the presented analysis could provide a new method to specifically evaluate a surface transition temperature of polymers, with the same lateral resolution as the gas cluster beam. [Figure not available: see fulltext.

  19. Temperature Dependence of Arn+ Cluster Backscattering from Polymer Surfaces: a New Method to Determine the Surface Glass Transition Temperature.

    Science.gov (United States)

    Poleunis, Claude; Cristaudo, Vanina; Delcorte, Arnaud

    2018-01-01

    In this work, time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to study the intensity variations of the backscattered Ar n + clusters as a function of temperature for several amorphous polymer surfaces (polyolefins, polystyrene, and polymethyl methacrylate). For all these investigated polymers, our results show a transition of the ratio Ar 2 + /(Ar 2 + + Ar 3 + ) when the temperature is scanned from -120 °C to +125 °C (the exact limits depend on the studied polymer). This transition generally spans over a few tens of degrees and the temperature of the inflection point of each curve is always lower than the bulk glass transition temperature (T g ) reported for the considered polymer. Due to the surface sensitivity of the cluster backscattering process (several nanometers), the presented analysis could provide a new method to specifically evaluate a surface transition temperature of polymers, with the same lateral resolution as the gas cluster beam. Graphical abstract ᅟ.

  20. The Wafer and Diffusion Lot Dependence of Surface Effects Resulting from Ionizing Radiation,

    Science.gov (United States)

    An investigation of the wafer and diffusion lot dependence of surface effects resulting from ionizing radiation was conducted by irradiating samples...of transistors. The transistors were selected by the wafer and diffusion lot from which they were produced. Both NPN and PNP transistors were...the diffusion lot . With the PNP’s which were not effected to the same extent as the NPN’s the dependence on the wafer or diffusion lot was not

  1. Area-Specific Cell Stimulation via Surface-Mediated Gene Transfer Using Apatite-Based Composite Layers

    Directory of Open Access Journals (Sweden)

    Yushin Yazaki

    2015-04-01

    Full Text Available Surface-mediated gene transfer systems using biocompatible calcium phosphate (CaP-based composite layers have attracted attention as a tool for controlling cell behaviors. In the present study we aimed to demonstrate the potential of CaP-based composite layers to mediate area-specific dual gene transfer and to stimulate cells on an area-by-area basis in the same well. For this purpose we prepared two pairs of DNA–fibronectin–apatite composite (DF-Ap layers using a pair of reporter genes and pair of differentiation factor genes. The results of the area-specific dual gene transfer successfully demonstrated that the cells cultured on a pair of DF-Ap layers that were adjacently placed in the same well showed specific gene expression patterns depending on the gene that was immobilized in theunderlying layer. Moreover, preliminary real-time PCR results indicated that multipotential C3H10T1/2 cells may have a potential to change into different types of cells depending on the differentiation factor gene that was immobilized in the underlying layer, even in the same well. Because DF-Ap layers have a potential to mediate area-specific cell stimulation on their surfaces, they could be useful in tissue engineering applications.

  2. Comparative analysis of surface soil moisture retrieval using VSWI and TVDI in karst areas

    Science.gov (United States)

    Yan, Hongbo; Zhou, Guoqing; Lu, Xianjian

    2015-12-01

    Vegetation Supply Water Index (VSWI) and Temperature Vegetation dryness Index (TVDI) are two most commonly used methods for surface soil moisture (SSM) retrieval using electromagnetic spectrum of visible, near infrared and thermal infrared band. Both of them take into account the effect of vegetation index (VI) and surface temperature (Ts) on SSM. A comparative analysis of the ability and effect of the two methods for SSM retrieval in karst areas was carried out, using the remote sensing data of Landsat 8 OLI_TIRS. The study area is located in Guilin, which is a typical karst area. The experimental results show that TVDI is more suitable for SSM retrieval in karst areas.

  3. Influence of Ecological Factors on Estimation of Impervious Surface Area Using Landsat 8 Imagery

    Directory of Open Access Journals (Sweden)

    Yuqiu Jia

    2017-07-01

    Full Text Available Estimation of impervious surface area is important to the study of urban environments and social development, but surface characteristics, as well as the temporal, spectral, and spatial resolutions of remote sensing images, influence the estimation accuracy. To investigate the effects of regional environmental characteristics on the estimation of impervious surface area, we divided China into seven sub-regions based on climate, soil type, feature complexity, and vegetation phenology: arid and semi-arid areas, Huang-Huai-Hai winter wheat production areas, typical temperate regions, the Pearl River Delta, the middle and lower reaches of the Yangtze River, typical tropical and subtropical regions, and the Qinghai Tibet Plateau. Impervious surface area was estimated from Landsat 8 images of five typical cities, including Yinchuan, Shijiazhuang, Shenyang, Ningbo, and Kunming. Using the linear spectral unmixing method, impervious and permeable surface areas were determined at the pixel-scale based on end-member proportions. We calculated the producer’s accuracy, user’s accuracy, and overall accuracy to assess the estimation accuracy, and compared the accuracies among images acquired from different seasons and locations. In tropical and subtropical regions, vegetation canopies can confound the identification of impervious surfaces and, thus, images acquired in winter, early spring, and autumn are most suitable; estimations in the Pearl River Delta, the middle and lower reaches of the Yangtze River are influenced by soil, vegetation phenology, vegetation canopy, and water, and images acquired in spring, summer, and autumn provide the best results; in typical temperate areas, images acquired from spring to autumn are most effective for estimations; in winter wheat-growing areas, images acquired throughout the year are suitable; and in arid and semi-arid areas, summer and early autumn, during which vegetation is abundant, are the optimal seasons for

  4. Assessing surface water quality and its relation with urban land cover changes in the Lake Calumet area, Greater Chicago.

    Science.gov (United States)

    Wilson, Cyril; Weng, Qihao

    2010-05-01

    Urban land use and land cover change significantly affect spatial and temporal patterns of runoff, which in turn impacts surface water quality. With the exponential growth in urban areas over the past three decades, changes in land use and land cover to cater for the growth of cities has been a conspicuous spectacle in urban spaces. The main goal of this study was to assess the impacts of land cover change on runoff and surface water quality using a partial area hydrology framework. The study employed ArcHydro GIS extension and a modified version of Long-Term Hydrologic and Nonpoint Source Pollution model (L-THIA-NPS) in estimating runoff and nonpoint source pollutant concentration around Lake Calumet between 1992 and 2001. Data employed include National Land Cover Data set, rainfall data, digital elevation model (DEM), Soil Survey Geographic (SSURGO) data, and The United States Environmental Protection Agency's STORET (storage and retrieval) water quality data. The model was able to predict surface water quality reasonably well over the study period. Sensitivity analysis facilitated a manual calibration of the model. Model validation was executed by comparing simulated results following calibration and observed water quality data for the study area. The study demonstrates that the level of concentration of nonpoint source pollutants in surface water within an urban watershed heavily depends on the spatiotemporal variations in areas that contribute towards runoff compared to the spatial extent of change in major land use/land cover.

  5. CLPX-Satellite: EO-1 Hyperion Surface Reflectance, Snow-Covered Area, and Grain Size

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set consists of apparent surface reflectance, subpixel snow-covered area and grain size collected from the Hyperion hyperspectral imager. The Hyperion...

  6. Wind dependence of ambient noise in a biologically rich coastal area.

    Science.gov (United States)

    Mathias, Delphine; Gervaise, Cédric; Di Iorio, Lucia

    2016-02-01

    The wind dependence of acoustic spectrum between 100 Hz and 16 kHz is investigated for coastal biologically rich areas. The analysis of 5 months of continuous measurements run in a 10 m deep shallow water environment off Brittany (France) showed that wind dependence of spectral levels is subject to masking by biological sounds. When dealing with raw data, the wind dependence of spectral levels was not significant for frequencies where biological sounds were present (2 to 10 kHz). An algorithm developed by Kinda, Simard, Gervaise, Mars, and Fortier [J. Acoust. Soc. Am. 134(1), 77-87 (2013)] was used to automatically filter out the loud distinctive biological contribution and estimated the ambient noise spectrum. The wind dependence of ambient noise spectrum was always significant after application of this filter. A mixture model for ambient noise spectrum which accounts for the richness of the soundscape is proposed. This model revealed that wind dependence holds once the wind speed was strong enough to produce sounds higher in amplitude than the biological chorus (9 kn at 3 kHz, 11 kn at 8 kHz). For these higher wind speeds, a logarithmic affine law was adequate and its estimated parameters were compatible with previous studies (average slope 27.1 dB per decade of wind speed increase).

  7. Interdependence between body surface area and ultraviolet B dose in vitamin D production

    DEFF Research Database (Denmark)

    Bogh, M K B; Schmedes, Anne; Philipsen, P A

    2011-01-01

    Ultraviolet (UV) B radiation increases serum vitamin D level expressed as 25-hydroxyvitamin-D(3) [25(OH)D], but the relationship to body surface area and UVB dose needs investigation.......Ultraviolet (UV) B radiation increases serum vitamin D level expressed as 25-hydroxyvitamin-D(3) [25(OH)D], but the relationship to body surface area and UVB dose needs investigation....

  8. Estimation of surface area concentration of workplace incidental nanoparticles based on number and mass concentrations

    Science.gov (United States)

    Park, J. Y.; Ramachandran, G.; Raynor, P. C.; Kim, S. W.

    2011-10-01

    Surface area was estimated by three different methods using number and/or mass concentrations obtained from either two or three instruments that are commonly used in the field. The estimated surface area concentrations were compared with reference surface area concentrations (SAREF) calculated from the particle size distributions obtained from a scanning mobility particle sizer and an optical particle counter (OPC). The first estimation method (SAPSD) used particle size distribution measured by a condensation particle counter (CPC) and an OPC. The second method (SAINV1) used an inversion routine based on PM1.0, PM2.5, and number concentrations to reconstruct assumed lognormal size distributions by minimizing the difference between measurements and calculated values. The third method (SAINV2) utilized a simpler inversion method that used PM1.0 and number concentrations to construct a lognormal size distribution with an assumed value of geometric standard deviation. All estimated surface area concentrations were calculated from the reconstructed size distributions. These methods were evaluated using particle measurements obtained in a restaurant, an aluminum die-casting factory, and a diesel engine laboratory. SAPSD was 0.7-1.8 times higher and SAINV1 and SAINV2 were 2.2-8 times higher than SAREF in the restaurant and diesel engine laboratory. In the die casting facility, all estimated surface area concentrations were lower than SAREF. However, the estimated surface area concentration using all three methods had qualitatively similar exposure trends and rankings to those using SAREF within a workplace. This study suggests that surface area concentration estimation based on particle size distribution (SAPSD) is a more accurate and convenient method to estimate surface area concentrations than estimation methods using inversion routines and may be feasible to use for classifying exposure groups and identifying exposure trends.

  9. Estimation of surface area concentration of workplace incidental nanoparticles based on number and mass concentrations

    International Nuclear Information System (INIS)

    Park, J. Y.; Ramachandran, G.; Raynor, P. C.; Kim, S. W.

    2011-01-01

    Surface area was estimated by three different methods using number and/or mass concentrations obtained from either two or three instruments that are commonly used in the field. The estimated surface area concentrations were compared with reference surface area concentrations (SA REF ) calculated from the particle size distributions obtained from a scanning mobility particle sizer and an optical particle counter (OPC). The first estimation method (SA PSD ) used particle size distribution measured by a condensation particle counter (CPC) and an OPC. The second method (SA INV1 ) used an inversion routine based on PM1.0, PM2.5, and number concentrations to reconstruct assumed lognormal size distributions by minimizing the difference between measurements and calculated values. The third method (SA INV2 ) utilized a simpler inversion method that used PM1.0 and number concentrations to construct a lognormal size distribution with an assumed value of geometric standard deviation. All estimated surface area concentrations were calculated from the reconstructed size distributions. These methods were evaluated using particle measurements obtained in a restaurant, an aluminum die-casting factory, and a diesel engine laboratory. SA PSD was 0.7–1.8 times higher and SA INV1 and SA INV2 were 2.2–8 times higher than SA REF in the restaurant and diesel engine laboratory. In the die casting facility, all estimated surface area concentrations were lower than SA REF . However, the estimated surface area concentration using all three methods had qualitatively similar exposure trends and rankings to those using SA REF within a workplace. This study suggests that surface area concentration estimation based on particle size distribution (SA PSD ) is a more accurate and convenient method to estimate surface area concentrations than estimation methods using inversion routines and may be feasible to use for classifying exposure groups and identifying exposure trends.

  10. Changes in the intestinal microvillous surface area during reproduction and ageing in the female rat.

    OpenAIRE

    Pénzes, L; Regius, O

    1985-01-01

    A morphometric study has been undertaken of the changes that occur in the microvillous surface area of young, pregnant, lactating, old and senescent rats. It has been shown that the microvilli are organelles with a quite stable conformation and that they exhibit no large scale dimensional changes throughout almost the entire life span. Lactation, however, does induce an apparent increase in microvillous surface area which may be associated with the significant changes which occur to the struc...

  11. Relationship between specific surface area and spatial correlation functions for anisotropic porous media

    Energy Technology Data Exchange (ETDEWEB)

    Berryman, J.G.

    1987-01-01

    A result of Debye, Anderson, and Brumberger (P. Debye, H. R. Anderson, Jr., and H. Brumberger, J. Appl. Phys. 28, 679 (1957)) for isotropic porous media states that the derivative of the two-point spatial correlation at the origin is equal to minus one-quarter of the specific surface area. This result is generalized for nonisotropic media by noting that the angular average of the anisotropic two-point spatial correlation function has the same relationship to the specific surface area.

  12. Potential dependence of surface crystal structure of iron passive films in borate buffer solution

    International Nuclear Information System (INIS)

    Deng, Huihua; Nanjo, Hiroshi; Qian, Pu; Santosa, Arifin; Ishikawa, Ikuo; Kurata, Yoshiaki

    2007-01-01

    The effect of passivation potential on surface crystal structure, apparent thickness and passivity of oxide films formed on pure iron prepared by plasma sputter deposition was investigated. The crystallinity was improved with passivation potential and the width of atomically flat terraces was expanded to 6 nm when passivating at 750 mV for 15 min, as observed by ex situ scanning tunneling microscopy (STM) after aging in air (<30% RH). Apparent thickness and passivity are linearly dependent on passivation potential. The former weakly depends on passivation duration, the latter strongly depends on passivation duration. This is well explained by the correlation between crystal structure and passivity

  13. Molecular-dynamics theory of the temperature-dependent surface phonons of W(001)

    International Nuclear Information System (INIS)

    Wang, C.Z.; Fasolino, A.; Tosatti, E.

    1987-04-01

    We study the temperature-dependent zone-boundary surface phonons across the c(2x2)→1x1 reconstruction phase transition of the clean W(001) surface. Velocity-velocity correlations and hence the phonon spectral densities are calculated by molecular dynamics for the surface atoms of a finite thickness (001) slab, with interatomic potentials established in a previous study of the surface statics. Our calculated k = (1/2,1/2)(2π/a) surface phonon are dominated by three main low-frequency modes. Of these, the longitudinal and the shear horizontal are reconstruction-related and display critical broadening and softening at the phase transition, while the third, the shear vertical, is basically unaffected. The reconstruction phase mode, shear horizontal, appears to be responsible for the phase fluctuations which destroy long-range order at the transition. (author). 30 refs, 12 figs

  14. Lake Chad Total Surface Water Area as Derived from Land Surface Temperature and Radar Remote Sensing Data

    Directory of Open Access Journals (Sweden)

    Frederick Policelli

    2018-02-01

    Full Text Available Lake Chad, located in the middle of the African Sahel belt, underwent dramatic decreases in the 1970s and 1980s leaving less than ten percent of its 1960s surface water extent as open water. In this paper, we present an extended record (dry seasons 1988–2016 of the total surface water area of the lake (including both open water and flooded vegetation derived using Land Surface Temperature (LST data (dry seasons 2000–2016 from the NASA Terra MODIS sensor and EUMETSAT Meteosat-based LST measurements (dry seasons 1988–2001 from an earlier study. We also examine the total surface water area for Lake Chad using radar data (dry seasons 2015–2016 from the ESA Sentinel-1a mission. For the limited number of radar data sets available to us (18 data sets, we find on average a close match between the estimates from these data and the corresponding estimates from LST, though we find spatial differences in the estimates using the two types of data. We use these spatial differences to adjust the record (dry seasons 2000–2016 from MODIS LST. Then we use the adjusted record to remove the bias of the existing LST record (dry seasons 1988–2001 derived from Meteosat measurements and combine the two records. From this composite, extended record, we plot the total surface water area of the lake for the dry seasons of 1988–1989 through 2016–2017. We find for the dry seasons of 1988–1989 to 2016–2017 that the maximum total surface water area of the lake was approximately 16,800 sq. km (February and May, 2000, the minimum total surface water area of the lake was approximately 6400 sq. km (November, 1990, and the average was approximately 12,700 sq. km. Further, we find the total surface water area of the lake to be highly variable during this period, with an average rate of increase of approximately 143 km2 per year.

  15. Geohydrology and susceptibility of major aquifers to surface contamination in Alabama, area 7

    Science.gov (United States)

    Mooty, W.S.

    1987-01-01

    The geohydrology and susceptibility of the seven major aquifers to surface contamination in Area 7 - Bibb, Dallas, Hale, Perry, and Wilcox Counties, are described. Aquifers in the northern part of the study area are in Paleozoic limestones and dolomite formations. Deposits in the central part of the study area are predominately of Cretaceous age and contain the Coker, Gordo, and Eutaw aquifers. Although the southern part of the study area has many deposits of Tertiary age, the Ripley Formation of Cretaceous age is the major aquifer. Contamination of any of the major aquifers is improbable because the majority of the recharge area for the primary aquifers is woodland, pasture, or farmland. Downdip from their outcrops, the major aquifers in the study area are protected from land surface contamination by relatively impermeable layers of clay and chalk. The aquifers that are highly susceptible to contamination are the ones in the limestone and dolomite formations in northern Bibb County. Sinkholes exist in the recharge area of these formations and could provide a direct link for contaminates from the land surface to the water table. An area northeast of the Selma well field is also highly susceptible to contamination. The Eutaw Formation in this area is overlain by alluvial deposits that could increase recharge to the aquifer by slowing the runoff rate of surface water. (USGS)

  16. Changes in Thickness and Surface Area of the Human Cortex and Their Relationship with Intelligence

    NARCIS (Netherlands)

    Schnack, Hugo G.; Van Haren, Neeltje E M; Brouwer, Rachel M.; Evans, Alan; Durston, Sarah; Boomsma, Dorret I.; Kahn, René S.; Hulshoff Pol, Hilleke E.

    2015-01-01

    Changes in cortical thickness over time have been related to intelligence, but whether changes in cortical surface area are related to general cognitive functioning is unknown. We therefore examined the relationship between intelligence quotient (IQ) and changes in cortical thickness and surface

  17. Greenland surface mass-balance observations from the ice-sheet ablation area and local glaciers

    DEFF Research Database (Denmark)

    Machguth, Horst; Thomsen, Henrik H.; Weidick, Anker

    2016-01-01

    Glacier surface mass-balance measurements on Greenland started more than a century ago, but no compilation exists of the observations from the ablation area of the ice sheet and local glaciers. Such data could be used in the evaluation of modelled surface mass balance, or to document changes in g...

  18. Greenland surface mass-balance observations from the ice-sheet ablation area and local glaciers

    NARCIS (Netherlands)

    Machguth, Horst; Thomsen, Henrik H.; Weidick, Anker; Ahlstrøm, Andreas P.; Abermann, Jakob; Andersen, Morten L.; Andersen, Signe B.; Bjørk, Anders A.; Box, Jason E.; Braithwaite, Roger J.; Bøggild, Carl E.; Citterio, Michele; Clement, Poul; Colgan, William; Fausto, Robert S.; Gleie, Karin; Gubler, Stefanie; Hasholt, Bent; Hynek, Bernhard; Knudsen, Niels T.; Larsen, Signe H.; Mernild, Sebastian H.; Oerlemans, Johannes; Oerter, Hans; Olesen, Ole B.; Smeets, C. J P Paul; Steffen, Konrad; Stober, Manfred; Sugiyama, Shin; Van As, Dirk; Van Den Broeke, Michiel R.; Van De Wal, Roderik S W

    2016-01-01

    Glacier surface mass-balance measurements on Greenland started more than a century ago, but no compilation exists of the observations from the ablation area of the ice sheet and local glaciers. Such data could be used in the evaluation of modelled surface mass balance, or to document changes in

  19. Dependence of the runaway greenhouse threshold on the surface water distribution for Earth-like planets

    Science.gov (United States)

    Kodama, T.; Nitta, A.; Genda, H.; Oishi, R.; Abe-Ouchi, A.; Abe, Y.

    2017-12-01

    Liquid water is one of the important materials that affect the climate and habitability on a terrestrial planet. Liquid water entirely vaporizes when planets receive insolation above a certain critical value, which is called the runaway greenhouse threshold. This threshold forms the inner most limit of the habitable zone. In general, it is assumed that an Earth-like planet with oceans is a potentially habitable planet. Such a planet is implicitly assumed to be a planet whose surface is covered with oceans. Thus, most of previous studies estimated the runaway greenhouse threshold for such planets. Abe et al. (2011) suggest that the runaway greenhouse threshold significantly depends on the distribution of water on the surface. The distribution of the surface water is determined by the surface topography, the surface water flow and the transport of water vapor in the atmosphere. Here, we investigate the effects of the distribution of surface water on the runaway greenhouse threshold for Earth-sized planets using a three-dimensional dynamic atmosphere model. We recognized two climate regimes: the land planet regime, which has dry low latitude and wet high latitude regions, and the aqua planet regime, which is globally wet. We showed that each regime is controlled by the width of the Hadley circulation, the amount of surface water, and the planetary topography. We found that the runaway greenhouse threshold continuously varies with the surface water distribution from about 130% (an aqua planet) to 180% (the extreme case of a land planet) of the present insolation at Earth's orbit. Our results indicate that the inner edge of the habitable zone is not a single sharp boundary, but a border whose location varies depending on planetary surface condition, such as the amount of surface water.

  20. Dependence of the textural properties and surface species of ZnO ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 40; Issue 3. Dependence of the textural properties and surface species of ZnO photocatalytic materials on the type of precipitating agent used in the hydrothermal synthesis. I STAMBOLOVA V BLASKOV D STOYANOVA I AVRAMOVA L DIMITROV K MILENOVA K ...

  1. Surface-Dependent Transitions during Self-Assembly of Phospholipid Membranes on Mica, Silica, and Glass

    Czech Academy of Sciences Publication Activity Database

    Beneš, Martin; Billy, D.; Benda, Aleš; Speijer, H.; Hof, Martin; Hermens, W. T.

    2004-01-01

    Roč. 20, č. 23 (2004), s. 10129-10137 ISSN 0743-7463 R&D Projects: GA MŠk LN00A032 Institutional research plan: CEZ:AV0Z4040901 Keywords : silica and glass * phospholipid * surface-dependent Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.295, year: 2004

  2. A method for calculating the time-dependent surface temperature of a cylinder containing radioactive waste

    International Nuclear Information System (INIS)

    Fynbo, P.B.

    1981-02-01

    A method is described by which the surface temperature of a steel cylinder containing radioactive waste can be calculated. The method assumes a time-dependent continuous line source in cylindrical symmetry and it applies Laplace transformation. The resultant laplace transform is approximated and then inverted (by convolution). The method is computationally fast and future generalisations to similar problems are suggested. (author)

  3. Models of bedrock surface and overburden thickness over Olkiluoto island and nearby sea area

    Energy Technology Data Exchange (ETDEWEB)

    Moenkkoenen, H. [WSP Finland Oy, Helsinki (Finland)

    2012-04-15

    In this report, a model of bedrock surface and a model of overburden thickness over the Olkiluoto Island and the nearby sea area are presented. Also in purpose to produce material for biosphere and radionuclide transport modelling, stratigraphy models of different sediment layers were created at two priority areas north and south of the Olkiluoto Island. The work concentrated on the collection and description of available data of bedrock surface and overburden thickness. Because the information on the bedrock surface and overburden is collected from different sources and is based on a number of types of data the quality and applicability of data sets varies. Consequently also the reliability in different parts of the models varies. Input data for the bedrock surface and overburden thickness models include 2928 single points and additional outcrops observations (611 polygons) in the modelled area. In addition, the input data include 173 seismic refraction lines (6534 points) and acousticseismic sounding lines (26655 points from which 13721 points are located in model area) in the Olkiluoto offshore area. The average elevation of bedrock surface in area is 2.1 metres above the sea level. The average thickness of overburden is 2.5 metres varying typically between 2 - 4 metres. Thickest overburden covers (approximately 16 metres) of terrestrial area are located at the western end of the Olkiluoto Island and in sea basin south of the island. (orig.)

  4. Surface area loss and increased sphericity account for the splenic entrapment of subpopulations of Plasmodium falciparum ring-infected erythrocytes.

    Directory of Open Access Journals (Sweden)

    Innocent Safeukui

    Full Text Available Ex vivo perfusion of human spleens revealed innate retention of numerous cultured Plasmodium falciparum ring-infected red blood cells (ring-iRBCs. Ring-iRBC retention was confirmed by a microsphiltration device, a microbead-based technology that mimics the mechanical filtering function of the human spleen. However, the cellular alterations underpinning this retention remain unclear. Here, we use ImageStream technology to analyze infected RBCs' morphology and cell dimensions before and after fractionation with microsphiltration. Compared to fresh normal RBCs, the mean cell membrane surface area loss of trophozoite-iRBCs, ring-iRBCs and uninfected co-cultured RBCs (uRBCs was 14.2% (range: 8.3-21.9%, 9.6% (7.3-12.2% and 3.7% (0-8.4, respectively. Microsphilters retained 100%, ∼50% and 4% of trophozoite-iRBCs, ring-iRBCs and uRBCs, respectively. Retained ring-iRBCs display reduced surface area values (estimated mean, range: 17%, 15-18%, similar to the previously shown threshold of surface-deficient RBCs retention in the human spleen (surface area loss: >18%. By contrast, ring-iRBCs that successfully traversed microsphilters had minimal surface area loss and normal sphericity, suggesting that these parameters are determinants of their retention. To confirm this hypothesis, fresh normal RBCs were exposed to lysophosphatidylcholine to induce a controlled loss of surface area. This resulted in a dose-dependent retention in microsphilters, with complete retention occurring for RBCs displaying >14% surface area loss. Taken together, these data demonstrate that surface area loss and resultant increased sphericity drive ring-iRBC retention in microsphilters, and contribute to splenic entrapment of a subpopulation of ring-iRBCs. These findings trigger more interest in malaria research fields, including modeling of infection kinetics, estimation of parasite load, and analysis of risk factors for severe clinical forms. The determination of the threshold of

  5. Trophic relationships in tidal flat areas: To what extent are tidal flats dependent on imported food?

    Science.gov (United States)

    Asmus, Harald; Asmus, Ragnhild M.

    In four intertidal areas of 'Königshafen' (island of Sylt, FRG), biomass and production of macrozoobenthos were measured monthly in 1980 and 1984. The areas were characterized by different macrofauna assemblages ( Nereis-Corophium belt, seagrass bed, Arenicola flat and mussel bed). Biomass and production of macrofauna were partitioned with regard to food preference of single species as well as to the food availability within their habitat. In the Nereis-Corophium belt, seagrass bed and the Arenicola flat, most of the secondary production of the macrofauna was formed by grazing animals. Secondary production of mussel beds was nearly 10 times higher than in the other three assemblages. The suspension feeder assemblage depended on planktonic food imported from outside the bay. Considering the secondary production of the total tidal flat area, suspension feeders dominated the other trophic groups, indicating a key position of this group relative to the other macrofaunal assemblages. Mussel beds regulate the seston input to other communities situated further landward. Because of this dominance of the suspension feeder group, the energy and material flow of the total tidal flat is strongly dependent on the seston input from the coastal waters of the North Sea or from other parts of the Wadden Sea.

  6. Estimation of cerebral surface area using vertical sectioning and magnetic resonance imaging: a stereological study.

    Science.gov (United States)

    Acer, Niyazi; Cankaya, Mehmet Niyazi; Işçi, Oznur; Baş, Orhan; Camurdanoğlu, Mehmet; Turgut, Mehmet

    2010-01-15

    Stereological techniques using isotropic uniform random and vertical uniform random sections have been used for surface area estimation. However, there are a few studies in which the surface area of the brain is estimated using the vertical section technique in a stereological approach. The objective of the current study was to apply the vertical section technique using cycloid test probes for estimation of cerebral surface area in magnetic resonance imaging (MRI). In this study, cerebral surface areas were estimated in a total of 13 young subjects (6 males, 7 females) who were free of any neurological symptoms and signs. The means (+/-S.D.) of the surface areas were 1619.92+/-140. 97 cm (2), 1625.69+/-147. 58 cm(2) and 1674.69+/-160. 60 cm(2) for 36, 18 and 12 vertical sections, respectively. The mean coefficient of error obtained by applying cycloid test lines that use a 2. 8-cm ratio of area associated with each cycloid was estimated at 0.05). In addition, the three models correlated well with each other. From these results, it is concluded that the vertical section technique is an unbiased, efficient and reliable method and is ideally suited to in vivo examination of MRI data for estimating the surface area of the brain. Hence, we suggest that estimation of surface area using MRI and stereology may be clinically relevant for assessing cortical atrophy as well as for investigating the structure and function of cerebral hemispheres. Copyright 2009 Elsevier B.V. All rights reserved.

  7. Scale dependency in effectiveness, isolation, and social-ecological spillover of protected areas.

    Science.gov (United States)

    Ament, Judith M; Cumming, Graeme S

    2016-08-01

    Protected areas are considered vital for the conservation of biodiversity. Given their central role in many conservation strategies, it is important to know whether they adequately protect biodiversity within their boundaries; whether they are becoming more isolated from other natural areas over time; and whether they play a role in facilitating or reducing land-cover change in their surroundings. We used matching methods and national and local analyses of land-cover change to evaluate the combined effectiveness (i.e., avoided natural-cover loss), isolation (i.e., changes in adjacent areas), and spillover effects (i.e., impacts on adjacent areas) of 19 national parks in South Africa from 2000 to 2009. All parks had either similar or lower rates of natural-cover loss than matched control samples. On a national level, mean net loss of natural cover and mean net gain of cultivation cover decreased with distance from park boundary, but there was considerable variation in trends around individual parks, providing evidence for both increased isolation and buffering of protected areas. Fourteen parks had significant positive spillover and reduced natural-cover loss in their surroundings, whereas five parks experienced elevated levels of natural-cover loss. Conclusions about social-ecological spillover effects from protected areas depended heavily on the measures of land-cover change used and the scale at which the results were aggregated. Our findings emphasize the need for high-resolution data when assessing spatially explicit phenomena such as land-cover change and challenge the usefulness of large-scale (coarse grain, broad extent) studies for understanding social-ecological dynamics around protected areas. © 2016 Society for Conservation Biology.

  8. Application of stereological methods to estimate post-mortem brain surface area using 3T MRI

    DEFF Research Database (Denmark)

    Furlong, Carolyn; García-Fiñana, Marta; Puddephat, Michael

    2013-01-01

    The Cavalieri and Vertical Sections methods of design based stereology were applied in combination with 3 tesla (i.e. 3T) Magnetic Resonance Imaging (MRI) to estimate cortical and subcortical volume, area of the pial surface, area of the grey-white matter boundary, and thickness of the cerebral c...

  9. Application of satellite images analysis to assess the variability of the surface thermal heat island distribution in urban areas

    Directory of Open Access Journals (Sweden)

    Fudała Janina

    2018-01-01

    Full Text Available One of the elements of the urban plans for adapting to climate change is to identify the range the urban heat island (UHI. To a relatively rare ground station network air temperature, one of the possible methods to identify this phenomenon in cities is the analysis of satellite images, and in particular the thermal images surface cities in conjunction with the land-use structure. In the publication is presented the application of indirect methods of determining surface characteristics of heat island in the cities of Upper Silesia Agglomeration on the basis of the analysis of the thermal images from the satellite Landsat for the period 1986-2016. It presents ways to interpret these images depending on the needs of determination the areas sensitive to the impact of the (UHI and define the areas where adaptation actions to the climate change should be undertaken.

  10. Application of satellite images analysis to assess the variability of the surface thermal heat island distribution in urban areas

    Science.gov (United States)

    Fudała, Janina; Nádudvari, Ádám; Bronder, Joachim; Fudała, Marta

    2018-01-01

    One of the elements of the urban plans for adapting to climate change is to identify the range the urban heat island (UHI). To a relatively rare ground station network air temperature, one of the possible methods to identify this phenomenon in cities is the analysis of satellite images, and in particular the thermal images surface cities in conjunction with the land-use structure. In the publication is presented the application of indirect methods of determining surface characteristics of heat island in the cities of Upper Silesia Agglomeration on the basis of the analysis of the thermal images from the satellite Landsat for the period 1986-2016. It presents ways to interpret these images depending on the needs of determination the areas sensitive to the impact of the (UHI) and define the areas where adaptation actions to the climate change should be undertaken.

  11. Shape-dependent Surface Energetics of Nanocrystalline TiO2

    Energy Technology Data Exchange (ETDEWEB)

    Park, T.J.; Wong, S.; Levchenko, A.A.; Zhou, H.; Navrotsky, A.

    2010-10-21

    We report the direct determination of surface enthalpies for nanophase TiO{sub 2} anatase with different morphologies derived from drop solution calorimetry in a molten sodium molybdate (3Na{sub 2}Ol{center_dot}4MoO{sub 3}) solvent at 702 C. The energetics of surface hydration has been measured using a Calvet microcalorimeter coupled with a gas dosing system. The surface enthalpies of hydrated surfaces for anatase TiO{sub 2} nanoparticles, nanowires and sea-urchin-like assemblies are 0.51 {+-} 0.05, 1.07 {+-} 0.28, and 1.29 {+-} 0.16 J m{sup -2}, respectively, whereas those of anhydrous surfaces are 0.74 {+-} 0.04, 1.24 {+-} 0.28, and 1.41 {+-} 0.16 J m{sup -2}, respectively. The trend in TiO{sub 2}, which shows higher surface enthalpies for more complex nanostructures, is consistent with that reported in ZnO. The shape-dependent surface enthalpy at the nanoscale level is discussed in terms of exposed surface structures. The enthalpies of hydration appear to be similar for all morphologies.

  12. Large Differences between Glaciers 3D Surface Extents and 2D Planar Areas in Central Tianshan

    Directory of Open Access Journals (Sweden)

    Xianwei Wang

    2017-04-01

    Full Text Available Most glaciers in China lie in high mountainous environments and have relatively large surface slopes. Common analyses consider glaciers’ projected areas (2D Area in a two-dimensional plane, which are much smaller than glacier’s topographic surface extents (3D Area. The areal difference between 2D planar areas and 3D surface extents exceeds −5% when the glacier’s surface slope is larger than 18°. In this study, we establish a 3D model in the Muzart Glacier catchment using ASTER GDEM data. This model is used to quantify the areal difference between glaciers’ 2D planar areas and their 3D surface extents in various slope zones and elevation bands by using the second Chinese Glacier Inventory (CGI2. Finally, we analyze the 2D and 3D area shrinking rate between 2007 and 2013 in Central Tianshan using glaciers derived from Landsat images by an object-based classification approach. This approach shows an accuracy of 89% when it validates by comparison of glaciers derived from Landsat and high spatial resolution GeoEye images. The extracted glaciers in 2007 also have an agreement of 89% with CGI2 data in the Muzart Glacier catchment. The glaciers’ 3D area is 34.2% larger than their 2D area from CGI2 in the Muzart Glacier catchment and by 27.9% in the entire Central Tianshan. Most underestimation occurs in the elevation bands of 4000–5000 m above sea level (a.s.l.. The 3D glacier areas reduced by 30 and 115 km2 between 2007 and 2013 in the Muzart Glacier catchment and Central Tianshan, being 37.0% and 27.6% larger than their 2D areas reduction, respectively. The shrinking rates decrease with elevation increase.

  13. Greenland surface mass-balance observations from the ice-sheet ablation area and local glaciers

    DEFF Research Database (Denmark)

    Machguth, Horst; Thomsen, Henrik H.; Weidick, Anker

    2016-01-01

    Glacier surface mass-balance measurements on Greenland started more than a century ago, but no compilation exists of the observations from the ablation area of the ice sheet and local glaciers. Such data could be used in the evaluation of modelled surface mass balance, or to document changes...... in glacier melt independently from model output. Here, we present a comprehensive database of Greenland glacier surface mass-balance observations from the ablation area of the ice sheet and local glaciers. The database spans the 123 a from 1892 to 2015, contains a total of similar to 3000 measurements from......-term time series of which there are only two exceeding 20 a. We use the data to analyse uncertainties in point measurements of surface mass balance, as well as to estimate surface mass-balance profiles for most regions of Greenland....

  14. Planar spatial correlations, anisotropy, and specific surface area of stationary random porous media

    International Nuclear Information System (INIS)

    Berryman, J.G.

    1998-01-01

    An earlier result of the author showed that an anisotropic spatial correlation function of a random porous medium could be used to compute the specific surface area when it is stationary as well as anisotropic by first performing a three-dimensional radial average and then taking the first derivative with respect to lag at the origin. This result generalized the earlier result for isotropic porous media of Debye et al. [J. Appl. Phys. 28, 679 (1957)]. The present article provides more detailed information about the use of spatial correlation functions for anisotropic porous media and in particular shows that, for stationary anisotropic media, the specific surface area can be related to the derivative of the two-dimensional radial average of the correlation function measured from cross sections taken through the anisotropic medium. The main concept is first illustrated using a simple pedagogical example for an anisotropic distribution of spherical voids. Then, a general derivation of formulas relating the derivative of the planar correlation functions to surface integrals is presented. When the surface normal is uniformly distributed (as is the case for any distribution of spherical voids), our formulas can be used to relate a specific surface area to easily measurable quantities from any single cross section. When the surface normal is not distributed uniformly (as would be the case for an oriented distribution of ellipsoidal voids), our results show how to obtain valid estimates of specific surface area by averaging measurements on three orthogonal cross sections. One important general observation for porous media is that the surface area from nearly flat cracks may be underestimated from measurements on orthogonal cross sections if any of the cross sections happen to lie in the plane of the cracks. This result is illustrated by taking the very small aspect ratio (penny-shaped crack) limit of an oblate spheroid, but holds for other types of flat surfaces as well

  15. Pore scale heterogeneity in the mineral distribution and surface area of porous rocks

    Science.gov (United States)

    Lai, Peter; Moulton, Kevin; Krevor, Samuel

    2014-05-01

    There are long-standing challenges in characterizing reactive transport in porous media at scales larger than individual pores. This hampers the prediction of the field-scale impact of geochemical processes on fluid flow [1]. This is a source of uncertainty for carbon dioxide injection, which results in a reactive fluid-rock system, particularly in carbonate rock reservoirs. A potential cause is the inability of the continuum approach to incorporate the impact of heterogeneity in pore-scale reaction rates. This results in part from pore-scale heterogeneities in surface area of reactive minerals [2,3]. The objective of this study was to quantify heterogeneity in reactive surface and observe the extent of its non-normal character. In this study we describe our work in using micron-scale x-ray imaging and other spectroscopic techniques for the purpose of describing the statistical distribution of reactive surface area within a porous medium, and identifying specific mineral phases and their distribution in 3-dimensions. Using in-house image processing techniques and auxilary charactersation with thin section, electron microscope and spectroscopic techniques we quantified the surface area of each mineral phase in the x-ray CT images. This quantification was validated against nitrogen BET surface area and backscattered electron imaging measurements of the CT-imaged samples. Distributions in reactive surface area for each mineral phase were constructed by calculating surface areas in thousands of randomly selected subvolume images of the total sample, each normalized to the pore volume in that image. In all samples, there is little correlation between the reactive surface area fraction and the volumetric fraction of a mineral in a bulk rock. Berea sandstone was far less heterogeneous and has a characteristic pore size at which a surface area distribution may be used to quantify heterogeneity. In carbonates, heterogeneity is more complex and surface area must be

  16. Technology of surface wastewater purification, including high-rise construction areas

    Science.gov (United States)

    Tsyba, Anna; Skolubovich, Yury

    2018-03-01

    Despite on the improvements in the quality of high-rise construction areas and industrial wastewater treatment, the pollution of water bodies continues to increase. This is due to the organized and unorganized surface untreated sewage entry into the reservoirs. The qualitative analysis of some cities' surface sewage composition is carried out in the work. Based on the published literature review, the characteristic contamination present in surface wastewater was identified. The paper proposes a new technology for the treatment of surface sewage and presents the results of preliminary studies.

  17. Estimating surface fluxes over the north Tibetan Plateau area with ASTER imagery

    Directory of Open Access Journals (Sweden)

    Weiqiang Ma

    2009-01-01

    Full Text Available Surface fluxes are important boundary conditions for climatological modeling and Asian monsoon system. The recent availability of high-resolution, multi-band imagery from the ASTER (Advanced Space-borne Thermal Emission and Reflection radiometer sensor has enabled us to estimate surface fluxes to bridge the gap between local scale flux measurements using micrometeorological instruments and regional scale land-atmosphere exchanges of water and heat fluxes that are fundamental for the understanding of the water cycle in the Asian monsoon system. A parameterization method based on ASTER data and field observations has been proposed and tested for deriving surface albedo, surface temperature, Normalized Difference Vegetation Index (NDVI, Modified Soil Adjusted Vegetation Index (MSAVI, vegetation coverage, Leaf Area Index (LAI, net radiation flux, soil heat flux, sensible heat flux and latent heat flux over heterogeneous land surface in this paper. As a case study, the methodology was applied to the experimental area of the Coordinated Enhanced Observing Period (CEOP Asia-Australia Monsoon Project (CAMP on the Tibetan Plateau (CAMP/Tibet, located at the north Tibetan Plateau. The ASTER data of 24 July 2001, 29 November 2001 and 12 March 2002 was used in this paper for the case of summer, winter and spring. To validate the proposed methodology, the ground-measured surface variables (surface albedo and surface temperature and land surface heat fluxes (net radiation flux, soil heat flux, sensible heat flux and latent heat flux were compared to the ASTER derived values. The results show that the derived surface variables and land surface heat fluxes in three different months over the study area are in good accordance with the land surface status. Also, the estimated land surface variables and land surface heat fluxes are in good accordance with ground measurements, and all their absolute percentage difference (APD is less than 10% in the validation sites

  18. Satellite remotely-sensed land surface parameters and their climatic effects on urban areas

    Science.gov (United States)

    Zoran, M.; Savastru, R.; Savastru, D.; Ciobanu, M.; Tautan, M. N.; Miclos, S.

    2009-04-01

    Rapid urbanization transforms the natural landscape to anthropogenic urban land and changes surface biogeophysical characteristics.Urban growth affects the ecology of cities in a number of ways, such as eliminating and fragmenting native habitats, modifying local climate conditions, and generating anthropogenic pollutants.Urbanization has changed many landscapes throughout the world with serious ecological consequences.To understand the ecology of urban systems, it is necessary to quantify the spatial and temporal patterns of urbanization, which often requires dynamic modeling and spatial analysis. Geospatial information provided by satellite remote sensing sensors and biogeophysical field data are very useful for urban landuse-landcover dynamics and impacts analysis. The spatial and spectral variability of urban environments present fundamental challenges to deriving accurate remote sensing information for urban areas. By integrating high-resolution and medium-resolution satellite imagery with other geospatial information, have been investigated several land surface parameters including impervious surfaces and land surface temperatures for Bucharest metropolitan area in Romania. Percent impervious surface was used to quantitatively define the spatial extent and development density of urban land use. Land surface temperatures were retrieved by using a single band algorithm that processes both thermal infrared satellite data and total atmospheric water vapour content. Land surface temperatures have been analysed for different land use and land cover categories both in urban as well as in periurban areas. Because of the removal of vegetative cover and the reduction in evaporation over urban impervious surfaces, the urban heterogeneity of land surface and associated spatial extents influence surface thermal conditions. In situ meteorological data were integrated to assess regional climatic conditions. The spatial structure of surface heating influenced by landscape

  19. Internal Energy Dependence of Molecular Condensation Coefficients Determined from Molecular Beam Surface Scattering Experiments

    Science.gov (United States)

    Sibener, S. J.; Lee, Y. T.

    1978-05-01

    An experiment was performed which confirms the existence of an internal mode dependence of molecular sticking probabilities for collisions of molecules with a cold surface. The scattering of a velocity selected effusive beam of CCl{sub 4} from a 90 K CC1{sub 4} ice surface has been studied at five translational velocities and for two different internal temperatures. At a surface temperature of 90 K (approx. 99% sticking probability) a four fold increase in reflected intensity was observed for the internally excited (560 K) CC1{sub 4} relative to the room temperature (298 K) CC1{sub 4} at a translational velocity of 2.5 X 10{sup 4} cm/sec. For a surface temperature of 90 K all angular distributions were found to peak 15{sup 0} superspecularly independent of incident velocity.

  20. Dependence of Ideality Factor in Lateral PNP Transistors on Surface Carrier Concentration

    Science.gov (United States)

    Li, Xingji; Yang, Jianqun; Barnaby, Hugh J.; Galloway, Kenneth F.; Schrimpf, Ronald D.; Fleetwood, Daniel M.; Liu, Chaoming

    2017-06-01

    The influence of surface carrier concentration on the ideality factor of excess base current (ΔIB) in gated lateral PNP (GLPNP) bipolar junction transistors (BJTs) induced by 1-MeV electrons is investigated. ΔIB in LPNP BJTs is impacted by the surface carrier density and radiation-induced interface traps. In GLPNP BJTs, the surface carrier concentration can be controlled by the voltage applied to a gate over the base region. The ideality factor changes after irradiation, and its dependence on emitter-base voltage (VEB) is a function of gate voltage. For the irradiated devices, as the gate voltage decreases from +20 to -5 V, the ideality factor for excess base current changes from a single slope to two-slope behavior. The majority carrier concentration at the surface of the base, controlled by the gate voltage, impacts the excess base current and its ideality factor.

  1. Prediction of Fermi-Surface Pressure Dependence in Rb and Cs

    DEFF Research Database (Denmark)

    Jan, J. P.; MacDonald, A. H.; Skriver, Hans Lomholt

    1980-01-01

    The linear muffin-tin orbitals method of band-structure calculation, combined with a Gaussian integration technique using special directions in the Brillouin zone, has been used to calculate Fermi radii and extremal cross-sectional areas of the Fermi surface in rubidium and cesium. Band shifts we...

  2. Microbial counts of food contact surfaces at schools depending on a feeding scheme

    Directory of Open Access Journals (Sweden)

    Nthabiseng Nhlapo

    2014-11-01

    Full Text Available The prominence of disease transmission between individuals in confined environments is a concern, particularly in the educational environment. With respect to school feeding schemes, food contact surfaces have been shown to be potential vehicles of foodborne pathogens. The aim of this study was to assess the cleanliness of the surfaces that come into contact with food that is provided to children through the National School Nutrition Programme in central South Africa. In each school under study, microbiological samples were collected from the preparation surface and the dominant hand and apron of the food handler. The samples were analysed for total viable counts, coliforms, Escherichia coli, Staphylococcus aureus and yeasts and moulds. The criteria specified in the British Columbia Guide for Environmental Health Officers were used to evaluate the results. Total viable counts were high for all surfaces, with the majority of colonies being too numerous to count (over 100 colonies per plate. Counts of organisms were relatively low, with 20% of the surfaces producing unsatisfactory enumeration of S. aureus and E. coli and 30% unsatisfactory for coliforms. Yeast and mould produced 50% and 60% unsatisfactory counts from preparation surfaces and aprons, respectively. Statistically significant differences could not be established amongst microbial counts of the surfaces, which suggests cross-contamination may have occurred. Contamination may be attributed to foodstuffs and animals in the vicinity of the preparation area rather than to the food handlers, because hands had the lowest counts of enumerated organisms amongst the analysed surfaces.

  3. Polarization dependent Pd deposition structure on LiNbO3 {0001} surface

    Science.gov (United States)

    Kim, Seungchul; Rappe, Andrew M.

    2011-03-01

    We investigate effects of polarization orientation on atomic structure of palladium deposited on lithium niobate (LiNb O3) {0001} surface, using density functional theory (DFT) and kinetic Monte Carlo (kMC) simulations. Adsorption, diffusion, aggregation and clustering process -- include geometries, paths and energies -- of Pd clusters were calculated from DFT simulations. It has been observed that energy barriers of Pd motions on the negatively poled (c-) surface are much larger than those on the positively poled surface (c+), which indicates the Pd motions on the c- surface are much slower than that of c+ surface. We demonstrate, using kMC with kinetic parameters from DFT, very slow motion of Pd on c- surface leads dispersed small clusters or atoms while fast motion on c+ surface leads large clusters, indicating larger Pd-covered area on c- surface than c+ after Pd deposition. This work has been supported by US-DOE (grant DE-FG02-07ER15920), and by AROSR (FA9550-07-1-0397). Computational support was provided by HPCMO of the US-DoD.

  4. Turbulent flows over superhydrophobic surfaces with shear-dependent slip length

    Science.gov (United States)

    Khosh Aghdam, Sohrab; Seddighi, Mehdi; Ricco, Pierre

    2015-11-01

    Motivated by recent experimental evidence, shear-dependent slip length superhydrophobic surfaces are studied. Lyapunov stability analysis is applied in a 3D turbulent channel flow and extended to the shear-dependent slip-length case. The feedback law extracted is recognized for the first time to coincide with the constant-slip-length model widely used in simulations of hydrophobic surfaces. The condition for the slip parameters is found to be consistent with the experimental data and with values from DNS. The theoretical approach by Fukagata (PoF 18.5: 051703) is employed to model the drag-reduction effect engendered by the shear-dependent slip-length surfaces. The estimated drag-reduction values are in very good agreement with our DNS data. For slip parameters and flow conditions which are potentially realizable in the lab, the maximum computed drag reduction reaches 50%. The power spent by the turbulent flow on the walls is computed, thereby recognizing the hydrophobic surfaces as a passive-absorbing drag-reduction method, as opposed to geometrically-modifying techniques that do not consume energy, e.g. riblets, hence named passive-neutral. The flow is investigated by visualizations, statistical analysis of vorticity and strain rates, and quadrants of the Reynolds stresses. Part of this work was funded by Airbus Group. Simulations were performed on the ARCHER Supercomputer (UKTC Grant).

  5. Spectrally adjusted surface reflectance and its dependence with NDVI for Landsat and Sentinel 2

    Science.gov (United States)

    Villaescusa, J. L.; Franch, B.; Roger, J. C.; Vermote, E.; Justice, C. O.

    2017-12-01

    Cross-calibration between sensors is necessary to bring measurements to a common radiometric scale; it allows a more complete monitoring of land surface processes and enhances data continuity and harmonization. However, differences in the Relative Spectral Response (RSR) of sensors generate uncertainties in the process (Teillet et al., 2004). For this reason, compensating for these differences is of great importance and can be achieved by using a spectral band adjustment factor (SBAF), which establishes a relationship between two spectrally adjusted bands. Nonetheless, this relationship has been shown to depend greatly on the surface's NDVI (Trishchenko et al., 2002) and therefore needs to be corrected. In this work, we use the Sentinel 2 and Landsat sensor's RSRs for both the Red and NIR bands to find the most accurate metric towards performing said relationship, and use surface reflectance spectral libraries with a wide variety of classes that include NDVI values ranging from -0.1 to 1 to analyze its dependence. We compute a quadratic fit of the metric used vs the surface's NDVI and propose an adjusted correction equation dependent on the NDVI value for both bands of all Landsat and Sentinel 2 sensors. Key words: Radiometric calibration, RSR, Spectral Adjustment, Landsat, Sentinel 2.

  6. Hydrothermal synthesis of high surface area ZIF-8 with minimal use of TEA

    Science.gov (United States)

    Butova, V. V.; Budnyk, A. P.; Bulanova, E. A.; Lamberti, C.; Soldatov, A. V.

    2017-07-01

    In this paper we present, for the first time, a simple hydrothermal recipe for the synthesis of ZIF-8 Metal-Organic Framework (MOF) with a large specific surface area (1340 m2/g by BET). An important feature of the method is that the product forms in aqueous medium under standard hydrothermal conditions without DMF and great excess of linker with the use of TEA as structure directing agent. The ZIF-8 crystal phase of the product was confirmed by XRD; this technique has been also exploited to check the crystallinity and to follow the changes in the MOF structure induced by heating. TGA and temperature dependent XRD testify the high thermal stability of the material (470 °C in N2 and at 400 °C in air). The IR spectral profile of the material provides a complete picture of vibrations assigned to the linker and the metal center. The systematic investigation of the products obtained by increasing the TEA amount in the reacting medium from 0 to 25.5 mol equivalent Zn2+, allowed us to understand its role and to find 2.6 mol equivalent Zn2+ as the minimum amount needed to obtain a single phase ZIF-8 material with the high standard reported above. The stability of the material under severe basic conditions makes it a promising candidate in heterogeneous catalysis. The material has shown high capacity in I2 uptake, making it interesting also for selective molecular adsorption.

  7. Reliable nanomaterial classification of powders using the volume-specific surface area method

    Energy Technology Data Exchange (ETDEWEB)

    Wohlleben, Wendel, E-mail: wendel.wohlleben@basf.com [Department of Material Physics, BASF SE (Germany); Mielke, Johannes [BAM–Federal Institute for Materials Research and Testing (Germany); Bianchin, Alvise [MBN Nanomaterialia s.p.a (Italy); Ghanem, Antoine [R& I Centre Brussels, Solvay (Belgium); Freiberger, Harald [Department of Material Physics, BASF SE (Germany); Rauscher, Hubert [European Commission, Nanobiosciences Unit, Joint Research Centre (Italy); Gemeinert, Marion; Hodoroaba, Vasile-Dan, E-mail: dan.hodoroaba@bam.de [BAM–Federal Institute for Materials Research and Testing (Germany)

    2017-02-15

    The volume-specific surface area (VSSA) of a particulate material is one of two apparently very different metrics recommended by the European Commission for a definition of “nanomaterial” for regulatory purposes: specifically, the VSSA metric may classify nanomaterials and non-nanomaterials differently than the median size in number metrics, depending on the chemical composition, size, polydispersity, shape, porosity, and aggregation of the particles in the powder. Here we evaluate the extent of agreement between classification by electron microscopy (EM) and classification by VSSA on a large set of diverse particulate substances that represent all the anticipated challenges except mixtures of different substances. EM and VSSA are determined in multiple labs to assess also the level of reproducibility. Based on the results obtained on highly characterized benchmark materials from the NanoDefine EU FP7 project, we derive a tiered screening strategy for the purpose of implementing the definition of nanomaterials. We finally apply the screening strategy to further industrial materials, which were classified correctly and left only borderline cases for EM. On platelet-shaped nanomaterials, VSSA is essential to prevent false-negative classification by EM. On porous materials, approaches involving extended adsorption isotherms prevent false positive classification by VSSA. We find no false negatives by VSSA, neither in Tier 1 nor in Tier 2, despite real-world industrial polydispersity and diverse composition, shape, and coatings. The VSSA screening strategy is recommended for inclusion in a technical guidance for the implementation of the definition.

  8. Polarization Dependence of Surface Enhanced Raman Scattering on a Single Dielectric Nanowire

    Directory of Open Access Journals (Sweden)

    Hua Qi

    2012-01-01

    Full Text Available Our measurements of surface enhanced Raman scattering (SERS on Ga2O3 dielectric nanowires (NWs core/silver composites indicate that the SERS enhancement is highly dependent on the polarization direction of the incident laser light. The polarization dependence of the SERS signal with respect to the direction of a single NW was studied by changing the incident light angle. Further investigations demonstrate that the SERS intensity is not only dependent on the direction and wavelength of the incident light, but also on the species of the SERS active molecule. The largest signals were observed on an NW when the incident 514.5 nm light was polarized perpendicular to the length of the NW, while the opposite phenomenon was observed at the wavelength of 785 nm. Our theoretical simulations of the polarization dependence at 514.5 nm and 785 nm are in good agreement with the experimental results.

  9. The Fungal Pathogen Candida glabrata Does Not Depend on Surface Ferric Reductases for Iron Acquisition

    Directory of Open Access Journals (Sweden)

    Franziska Gerwien

    2017-06-01

    Full Text Available Iron acquisition is a crucial virulence determinant for many bacteria and fungi, including the opportunistic fungal pathogens Candida albicans and C. glabrata. While the diverse strategies used by C. albicans for obtaining iron from the host are well-described, much less is known about the acquisition of this micronutrient from host sources by C. glabrata – a distant relative of C. albicans with closer evolutionary ties to Saccharomyces cerevisiae, which nonetheless causes severe clinical symptoms in humans. Here we show that C. glabrata is much more restricted than C. albicans in using host iron sources, lacking, for example, the ability to grow on transferrin and hemin/hemoglobin. Instead, C. glabrata is able to use ferritin and non-protein-bound iron (FeCl3 as iron sources in a pH-dependent manner. As in other fungal pathogens, iron-dependent growth requires the reductive high affinity (HA iron uptake system. Typically highly conserved, this uptake mechanism normally relies on initial ferric reduction by cell-surface ferric reductases. The C. glabrata genome contains only three such putative ferric reductases, which were found to be dispensable for iron-dependent growth. In addition and in contrast to C. albicans and S. cerevisiae, we also detected no surface ferric reductase activity in C. glabrata. Instead, extracellular ferric reduction was found in this and the two other fungal species, which was largely dependent on an excreted low-molecular weight, non-protein ferric reductant. We therefore propose an iron acquisition strategy of C. glabrata which differs from other pathogenic fungi, such as C. albicans, in that it depends on a limited set of host iron sources and that it lacks the need for surface ferric reductases. Extracellular ferric reduction by a secreted molecule possibly compensates for the loss of surface ferric reductase activity in the HA iron uptake system.

  10. Dependence of Lunar Surface Charging on Solar Wind Plasma Conditions and Solar Irradiation

    Science.gov (United States)

    Stubbs, T. J.; Farrell, W. M.; Halekas, J. S.; Burchill, J. K.; Collier, M. R.; Zimmerman, M. I.; Vondrak, R. R.; Delory, G. T.; Pfaff, R. F.

    2014-01-01

    The surface of the Moon is electrically charged by exposure to solar radiation on its dayside, as well as by the continuous flux of charged particles from the various plasma environments that surround it. An electric potential develops between the lunar surface and ambient plasma, which manifests itself in a near-surface plasma sheath with a scale height of order the Debye length. This study investigates surface charging on the lunar dayside and near-terminator regions in the solar wind, for which the dominant current sources are usually from the pohotoemission of electrons, J(sub p), and the collection of plasma electrons J(sub e) and ions J(sub i). These currents are dependent on the following six parameters: plasma concentration n(sub 0), electron temperature T(sub e), ion temperature T(sub i), bulk flow velocity V, photoemission current at normal incidence J(sub P0), and photo electron temperature T(sub p). Using a numerical model, derived from a set of eleven basic assumptions, the influence of these six parameters on surface charging - characterized by the equilibrium surface potential, Debye length, and surface electric field - is investigated as a function of solar zenith angle. Overall, T(sub e) is the most important parameter, especially near the terminator, while J(sub P0) and T(sub p) dominate over most of the dayside.

  11. Pore scale heterogeneity in the mineral distribution and reactive surface area of rocks

    Science.gov (United States)

    Lai, P. E.; Krevor, S. C.

    2013-12-01

    There are long-standing challenges in characterizing reactive transport in porous media at scales larger than individual pores. This hampers the prediction of the field-scale impact of geochemical processes on fluid flow [1]. This is a source of uncertainty for CO2 injection, which results in a reactive fluid-rock system, particularly in carbonate rock reservoirs. A potential cause is the inability of the continuum approach to incorporate the impact of heterogeneity in pore-scale reaction rates. This results in part from pore-scale heterogeneities in surface area of reactive minerals [2,3]. In this study we have created μm resolution 3D images of 3 sandstone and 4 carbonate rocks using x-ray microtomography. Using in-house image processing techniques and auxiliary characterisation with thin section, electron microscope and spectroscopic techniques we quantified the surface area of each mineral phase in the x-ray CT images. This quantification was validated against N2 BET surface area and He porosity measurements of the imaged samples. Distributions in reactive surface area for each mineral phase were constructed by calculating surface areas in thousands of randomly selected subvolume images of the total sample, each normalized to the pore volume in that image. In all samples, there is little correlation between the reactive surface area fraction and the volumetric fraction of a mineral in a bulk rock. Berea sandstone was far less heterogeneous and has a characteristic pore size at which a surface area distribution may be used to quantify heterogeneity. In carbonates, heterogeneity is more complex and surface area must be characterized at multiple length scales for an accurate description of reactive transport. [1] Maher, Steefel, Depaolo and Vianni (2006) Geochimica et Cosmochimica Acta, 70, 337-363 [2] Landrot, Ajo-Franklin, Yang, Cabrini and Steefel (2012) Chemical Geology 318-319, 113-125 [3] Li, Peters and Celia (2007) American Journal of Science 307, 1146

  12. Surface shear stress dependence of gas transfer velocity parameterizations using DNS

    Science.gov (United States)

    Fredriksson, S. T.; Arneborg, L.; Nilsson, H.; Handler, R. A.

    2016-10-01

    Air-water gas-exchange is studied in direct numerical simulations (DNS) of free-surface flows driven by natural convection and weak winds. The wind is modeled as a constant surface-shear-stress and the gas-transfer is modeled via a passive scalar. The simulations are characterized via a Richardson number Ri=Bν/u*4 where B, ν, and u* are the buoyancy flux, kinematic viscosity, and friction velocity respectively. The simulations comprise 0water gas-exchange, (ii) determine, for a given buoyancy flux, the wind speed at which gas transfer becomes primarily shear driven, and (iii) find an expression for the gas-transfer velocity for flows driven by both convection and shear. The evaluated gas transfer-velocity parametrizations are based on either the rate of turbulent kinetic energy dissipation, the surface flow-divergence, the surface heat-flux, or the wind-speed. The parametrizations based on dissipation or divergence show an unfavorable Ri dependence for flows with combined forcing whereas the parametrization based on heat-flux only shows a limited Ri dependence. The two parametrizations based on wind speed give reasonable estimates for the transfer-velocity, depending however on the surface heat-flux. The transition from convection- to shear-dominated gas-transfer-velocity is shown to be at Ri≈0.004. Furthermore, the gas-transfer is shown to be well represented by two different approaches: (i) additive forcing expressed as kg,sum =AShearu*|Ri/Ric+1| 1/4Sc-n where Ric=|AShear/ABuoy|4, and (ii) either buoyancy or shear dominated expressed as, kg=ABuoy|Bν| 1/4Sc-n, Ri>Ric or kg=AShearu*Sc-n, Riwater surface-characteristics.

  13. Variability of silver fir (Abies alba Mill. cones – variability structure of scale surface area

    Directory of Open Access Journals (Sweden)

    Aniszewska Monika

    2017-03-01

    Full Text Available This study was conducted on a batch of closed silver fir cones from Jawor Forest District and a mixture of scales from the seed extraction facility Grotniki. The scales were divided into three size classes corresponding to the bottom, middle and upper part of the cones and their area was measured with the Multi Scan Base v.18.03 software. Based on the sum of the inner and outer surface area of all scales, we then determined the total area of evaporation from the cones. In addition, the area of protruding scales was measured for differently sized scales from different parts of the cones. Previous studies have shown that the average outer surface of a closed cone, calculated as the sum of protruding scales, accounts for 10% of the outer surface of an open cone. Pictures of both scale surfaces with the internal seed bed and the external protrusions were taken using a scanning electron microscope. We noticed significant differences in dimension and shape of the channels and trichomes on the scale surface. On the inner side of the scales, we found a high diversity of trichomes of different lengths, whilst the outer side contained channels. Presumably, these characteristics affect the rate of water loss from the cones during desiccation and separation of the seed. In-depth knowledge on the evaporative surfaces of fir cones and scale structure will be helpful for optimizing the industrial processes of seed extraction.

  14. Evaluating polymer degradation with complex mixtures using a simplified surface area method.

    Science.gov (United States)

    Steele, Kandace M; Pelham, Todd; Phalen, Robert N

    2017-09-01

    Chemical-resistant gloves, designed to protect workers from chemical hazards, are made from a variety of polymer materials such as plastic, rubber, and synthetic rubber. One material does not provide protection against all chemicals, thus proper polymer selection is critical. Standardized testing, such as chemical degradation tests, are used to aid in the selection process. The current methods of degradation ratings based on changes in weight or tensile properties can be expensive and data often do not exist for complex chemical mixtures. There are hundreds of thousands of chemical products on the market that do not have chemical resistance data for polymer selection. The method described in this study provides an inexpensive alternative to gravimetric analysis. This method uses surface area change to evaluate degradation of a polymer material. Degradation tests for 5 polymer types against 50 complex mixtures were conducted using both gravimetric and surface area methods. The percent change data were compared between the two methods. The resulting regression line was y = 0.48x + 0.019, in units of percent, and the Pearson correlation coefficient was r = 0.9537 (p ≤ 0.05), which indicated a strong correlation between percent weight change and percent surface area change. On average, the percent change for surface area was about half that of the weight change. Using this information, an equivalent rating system was developed for determining the chemical degradation of polymer gloves using surface area.

  15. Study of measurement methods of ultrafine aerosols surface-area for characterizing occupational exposure

    International Nuclear Information System (INIS)

    Bau, S.

    2008-12-01

    This work aims at improving knowledge on ultrafine aerosols surface-area measurement. Indeed, the development of nano-technologies may lead to occupational exposure to airborne nano-structured particles, which involves a new prevention issue. There is currently no consensus concerning what parameter (mass, surface-area, number) should be measured. However, surface-area could be a relevant metric, since it leads to a satisfying correlation with biological effects when nano-structured particles are inhaled. Hence, an original theoretical work was performed to position the parameter of surface-area in relation to other aerosol characteristics. To investigate measurement techniques of nano-structured aerosols surface-area, the experimental facility CAIMAN (Characterization of Instruments for the Measurement of Aerosols of Nano-particles) was designed and built. Within CAIMAN, it is possible to produce nano-structured aerosols with varying and controlled properties (size, concentration, chemical nature, morphology, state-of-charge), stable and reproducible in time. The generated aerosols were used to experimentally characterize the response of the instruments in study (NSAM and AeroTrak 9000 TSI, LQ1-DC Matter Engineering). The response functions measured with monodisperse aerosols show a good agreement with the corresponding theoretical curves in a large size range, from 15 to 520 nm. Furthermore, hypotheses have been formulated to explain the reasonable biases observed when measuring poly-disperse aerosols. (author)

  16. Surface-dependent chemical equilibrium constants and capacitances for bare and 3-cyanopropyldimethylchlorosilane coated silica nanochannels

    DEFF Research Database (Denmark)

    Andersen, Mathias Bækbo; Frey, Jared; Pennathur, Sumita

    2011-01-01

    , and pK+ are constant and independent of surface composition. Our theoretical model consists of three parts: (i) a chemical equilibrium model of the bare or coated wall, (ii) a chemical equilibrium model of the buffered bulk electrolyte, and (iii) a self-consistent Gouy–Chapman–Stern triple-layer model...... of the electrochemical double layer coupling these two equilibrium models. To validate our model, we used both pH-sensitive dye-based capillary filling experiments as well as electro-osmotic current-monitoring measurements. Using our model we predict the dependence of ζ potential, surface charge density, and capillary...

  17. Analysis of relationships between NDVI and land surface temperature in coastal area

    Science.gov (United States)

    Ning, Jicai; Gao, Zhiqiang; Chen, Maosi

    2017-09-01

    Using Landsat 5 Thematic Mapper and Landsat 8 Operational Land Imager and Thermal Infrared Sensor imagery of the Yellow River Delta, this study analyzed the relationships between NDVI and LST (land surface temperature). Six Landsat images comprising two time series were used to calculate the land surface temperature and correlated vegetation indices. The Yellow River Delta area has expanded substantially because of the deposited sediment carried from upstream reaches of the river. Between 1986 and 2015, approximately 35% of the land use area of the Yellow River Delta has been transformed into salterns and aquaculture ponds. Overall, land use conversion has occurred primarily from poorly utilized land into highly utilized land. To analyze the variation of land surface temperature, a mono-window algorithm was applied to retrieve the regional land surface temperature. The results showed bilinear correlation between land surface temperature and the vegetation indices (i.e., Normalized Difference Vegetation Index, Adjusted-Normalized Vegetation Index, Soil-Adjusted Vegetation Index, and Modified Soil-Adjusted Vegetation Index). Generally, values of the vegetation indices greater than the inflection point mean the land surface temperature and the vegetation indices are correlated negatively, and vice versa. Land surface temperature in coastal areas is affected considerably by local seawater temperature and weather conditions.

  18. Relationship among land surface temperature and LUCC, NDVI in typical karst area.

    Science.gov (United States)

    Deng, Yuanhong; Wang, Shijie; Bai, Xiaoyong; Tian, Yichao; Wu, Luhua; Xiao, Jianyong; Chen, Fei; Qian, Qinghuan

    2018-01-12

    Land surface temperature (LST) can reflect the land surface water-heat exchange process comprehensively, which is considerably significant to the study of environmental change. However, research about LST in karst mountain areas with complex topography is scarce. Therefore, we retrieved the LST in a karst mountain area from Landsat 8 data and explored its relationships with LUCC and NDVI. The results showed that LST of the study area was noticeably affected by altitude and underlying surface type. In summer, abnormal high-temperature zones were observed in the study area, perhaps due to karst rocky desertification. LSTs among different land use types significantly differed with the highest in construction land and the lowest in woodland. The spatial distributions of NDVI and LST exhibited opposite patterns. Under the spatial combination of different land use types, the LST-NDVI feature space showed an obtuse-angled triangle shape and showed a negative linear correlation after removing water body data. In summary, the LST can be retrieved well by the atmospheric correction model from Landsat 8 data. Moreover, the LST of the karst mountain area is controlled by altitude, underlying surface type and aspect. This study provides a reference for land use planning, ecological environment restoration in karst areas.

  19. Surface Area of Patellar Facets: Inferential Statistics in the Iraqi Population

    Directory of Open Access Journals (Sweden)

    Ahmed Al-Imam

    2017-01-01

    Full Text Available Background. The patella is the largest sesamoid bone in the body; its three-dimensional complexity necessitates biomechanical perfection. Numerous pathologies occur at the patellofemoral unit which may end in degenerative changes. This study aims to test the presence of statistical correlation between the surface areas of patellar facets and other patellar morphometric parameters. Materials and Methods. Forty dry human patellae were studied. The morphometry of each patella was measured using a digital Vernier Caliper, electronic balance, and image analyses software known as ImageJ. The patellar facetal surface area was correlated with patellar weight, height, width, and thickness. Results. Inferential statistics proved the existence of linear correlation of total facetal surface area and patellar weight, height, width, and thickness. The correlation was strongest for surface area versus patellar weight. The lateral facetal area was found persistently larger than the medial facetal area, the p value was found to be <0.001 (one-tailed t-test for right patellae, and another significant p value of < 0.001 (one-tailed t-test was found for left patellae. Conclusion. These data are vital for the restoration of the normal biomechanics of the patellofemoral unit; these are to be consulted during knee surgeries and implant designs and can be of an indispensable anthropometric, interethnic, and biometric value.

  20. Identifying Priority Areas for Conservation: A Global Assessment for Forest-Dependent Birds

    Science.gov (United States)

    Buchanan, Graeme M.; Donald, Paul F.; Butchart, Stuart H. M.

    2011-01-01

    Limited resources are available to address the world's growing environmental problems, requiring conservationists to identify priority sites for action. Using new distribution maps for all of the world's forest-dependent birds (60.6% of all bird species), we quantify the contribution of remaining forest to conserving global avian biodiversity. For each of the world's partly or wholly forested 5-km cells, we estimated an impact score of its contribution to the distribution of all the forest bird species estimated to occur within it, and so is proportional to the impact on the conservation status of the world's forest-dependent birds were the forest it contains lost. The distribution of scores was highly skewed, a very small proportion of cells having scores several orders of magnitude above the global mean. Ecoregions containing the highest values of this score included relatively species-poor islands such as Hawaii and Palau, the relatively species-rich islands of Indonesia and the Philippines, and the megadiverse Atlantic Forests and northern Andes of South America. Ecoregions with high impact scores and high deforestation rates (2000–2005) included montane forests in Cameroon and the Eastern Arc of Tanzania, although deforestation data were not available for all ecoregions. Ecoregions with high impact scores, high rates of recent deforestation and low coverage by the protected area network included Indonesia's Seram rain forests and the moist forests of Trinidad and Tobago. Key sites in these ecoregions represent some of the most urgent priorities for expansion of the global protected areas network to meet Convention on Biological Diversity targets to increase the proportion of land formally protected to 17% by 2020. Areas with high impact scores, rapid deforestation, low protection and high carbon storage values may represent significant opportunities for both biodiversity conservation and climate change mitigation, for example through Reducing Emissions from

  1. Identifying priority areas for conservation: a global assessment for forest-dependent birds.

    Directory of Open Access Journals (Sweden)

    Graeme M Buchanan

    Full Text Available Limited resources are available to address the world's growing environmental problems, requiring conservationists to identify priority sites for action. Using new distribution maps for all of the world's forest-dependent birds (60.6% of all bird species, we quantify the contribution of remaining forest to conserving global avian biodiversity. For each of the world's partly or wholly forested 5-km cells, we estimated an impact score of its contribution to the distribution of all the forest bird species estimated to occur within it, and so is proportional to the impact on the conservation status of the world's forest-dependent birds were the forest it contains lost. The distribution of scores was highly skewed, a very small proportion of cells having scores several orders of magnitude above the global mean. Ecoregions containing the highest values of this score included relatively species-poor islands such as Hawaii and Palau, the relatively species-rich islands of Indonesia and the Philippines, and the megadiverse Atlantic Forests and northern Andes of South America. Ecoregions with high impact scores and high deforestation rates (2000-2005 included montane forests in Cameroon and the Eastern Arc of Tanzania, although deforestation data were not available for all ecoregions. Ecoregions with high impact scores, high rates of recent deforestation and low coverage by the protected area network included Indonesia's Seram rain forests and the moist forests of Trinidad and Tobago. Key sites in these ecoregions represent some of the most urgent priorities for expansion of the global protected areas network to meet Convention on Biological Diversity targets to increase the proportion of land formally protected to 17% by 2020. Areas with high impact scores, rapid deforestation, low protection and high carbon storage values may represent significant opportunities for both biodiversity conservation and climate change mitigation, for example through Reducing

  2. Identifying priority areas for conservation: a global assessment for forest-dependent birds.

    Science.gov (United States)

    Buchanan, Graeme M; Donald, Paul F; Butchart, Stuart H M

    2011-01-01

    Limited resources are available to address the world's growing environmental problems, requiring conservationists to identify priority sites for action. Using new distribution maps for all of the world's forest-dependent birds (60.6% of all bird species), we quantify the contribution of remaining forest to conserving global avian biodiversity. For each of the world's partly or wholly forested 5-km cells, we estimated an impact score of its contribution to the distribution of all the forest bird species estimated to occur within it, and so is proportional to the impact on the conservation status of the world's forest-dependent birds were the forest it contains lost. The distribution of scores was highly skewed, a very small proportion of cells having scores several orders of magnitude above the global mean. Ecoregions containing the highest values of this score included relatively species-poor islands such as Hawaii and Palau, the relatively species-rich islands of Indonesia and the Philippines, and the megadiverse Atlantic Forests and northern Andes of South America. Ecoregions with high impact scores and high deforestation rates (2000-2005) included montane forests in Cameroon and the Eastern Arc of Tanzania, although deforestation data were not available for all ecoregions. Ecoregions with high impact scores, high rates of recent deforestation and low coverage by the protected area network included Indonesia's Seram rain forests and the moist forests of Trinidad and Tobago. Key sites in these ecoregions represent some of the most urgent priorities for expansion of the global protected areas network to meet Convention on Biological Diversity targets to increase the proportion of land formally protected to 17% by 2020. Areas with high impact scores, rapid deforestation, low protection and high carbon storage values may represent significant opportunities for both biodiversity conservation and climate change mitigation, for example through Reducing Emissions from

  3. Magnetic-field-dependent morphology of self-organized Fe on stepped Si(111) surfaces

    International Nuclear Information System (INIS)

    Cougo dos Santos, M.; Geshev, J.; Pereira, L. G.; Schmidt, J. E.

    2009-01-01

    The present work reports on Fe thin films grown on vicinal Si(111) substrates via rf magnetron sputtering. The dependencies of the growth mode and magnetic properties of the obtained iron nanostructures on both crystallographic surface orientation and on the direction of the very weak stray magnetic field from the magnetron gun were studied. Scanning tunneling microscopy images showed strong dependence of the Fe grains' orientation on the stray field direction in relation to the substrate's steps demonstrating that, under appropriately directed magnetic field, Si surfaces can be used as templates for well-defined self-assembled iron nanostructures. Magneto-optical Kerr effect hysteresis loops showed an easy-axis coercivity almost one order of magnitude smaller for the film deposited with stray field applied along the steps, accompanied with a change in the magnetization reversal mode. Phenomenological models involving coherent rotation and/or domain-wall unpinning were used for the interpretation of these results.

  4. Dendrimer-induced leukocyte procoagulant activity depends on particle size and surface charge.

    Science.gov (United States)

    Dobrovolskaia, Marina A; Patri, Anil K; Potter, Timothy M; Rodriguez, Jamie C; Hall, Jennifer B; McNeil, Scott E

    2012-02-01

    Thrombogenicity associated with the induction of leukocyte procoagulant activity (PCA) is a common complication in sepsis and cancer. Since nanoparticles are increasingly used for drug delivery, their interaction with coagulation systems is an important part of the safety assessment. The purpose of this study was to investigate the effects of nanoparticle physicochemical properties on leukocyte PCA, and to get insight into the mechanism of PCA induction. A total of 12 formulations of polyamidoamine (PAMAM) dendrimers, varying in size and surface charge, were studied in vitro using recalcification time assay. Irrespective of their size, anionic and neutral dendrimers did not induce leukocyte PCA in vitro. Cationic particles induced PCA in a size- and charge-dependent manner. The mechanism of PCA induction was similar to that of doxorubicin. Cationic dendrimers were also found to exacerbate endotoxin-induced PCA. PAMAM dendrimer-induced leukocyte PCA depends on particle size, charge and density of surface groups.

  5. On the dependence of static flat seal efficiency to surface defects

    International Nuclear Information System (INIS)

    Ledoux, Y.; Lasseux, D.; Favreliere, H.; Samper, S.; Grandjean, J.

    2011-01-01

    We report on the role of the modal content of surface defects on static flat seal efficiency. The configuration under consideration is an annular contact between two surfaces, one holding all the defects, the other being assumed flat and infinitely rigid. The analysis is carried out on synthetic 'turned-like' surfaces generated by combinations of the first 50 vibrational eigen modes determined from modal discrete decomposition. The transmissivity of the contact, that fully characterizes the seal efficiency, is computed on the basis of a Reynolds model for incompressible flow. The dependence of the transmissivity upon the modal content of the surface defects is analyzed on a contact pressure range of common use employing a simplified deformation algorithm. Impact of the defects modal content is investigated statistically through a pair of experimental designs. It is shown that, i) the uncertainty on transmissivity, while considering a series of parts, can be drastically reduced if defect modes are well selected; ii) the transmissivity itself can be very significantly decreased when the defects modal content is conveniently controlled. While clearly indicating that the common surface roughness specification is generally not a relevant one to ensure a required seal performance, this work opens wide perspectives on the seal improvement by surface defects optimization only. - Highlights: → Computation of contact transmissivity qualifying static seal efficiency. → Statistical analysis of surface defects modal content on static flat seal. → Improvement of static flat seal efficiency. → Significant transmissivity reduction by convenient control of surface defects modes. → Drastic reduction of transmissivity uncertainty by surface defects modes selection.

  6. Concentration Dependences of the Surface Tension and Density of Solutions of Acetone-Ethanol-Water Systems at 293 K

    Science.gov (United States)

    Dadashev, R. Kh.; Dzhambulatov, R. S.; Mezhidov, V. Kh.; Elimkhanov, D. Z.

    2018-05-01

    Concentration dependences of the surface tension and density of solutions of three-component acetone-ethanol-water systems and the bounding binary systems at 273 K are studied. The molar volume, adsorption, and composition of surface layers are calculated. Experimental data and calculations show that three-component solutions are close to ideal ones. The surface tensions of these solutions are calculated using semi-empirical and theoretical equations. Theoretical equations qualitatively convey the concentration dependence of surface tension. A semi-empirical method based on the Köhler equation allows us to predict the concentration dependence of surface tension within the experimental error.

  7. Geohydrology and susceptibility of major aquifers to surface contamination in Alabama; area 11

    Science.gov (United States)

    Castleberry, R.D.; Moreland, R.S.; Scott, J.C.

    1989-01-01

    This report delineates and describes the geohydrology and susceptibility of major aquifers to contamination in Butler, Conecuh, Covington, Crenshaw, Escambia, and Monroe Counties, Alabama. The major aquifers are the Pliocene-Miocene, Upper Floridan, Lisbon, Nanafalia-Clayton, and Providence-Ripley. The largest pumping centers in the area are Andalusia and Monroeville, where groundwater use is about 5 and 4 million gal/day, respectively. Estimated maximum withdrawal in 1987 for all uses in the area was about 44 million gal/day. Depressions have developed in the potentiometric surfaces of the Lisbon aquifer near Andalusia and Opp, the Nanafalia-Clayton aquifer near Luverne, Andalusia, Beatrice, and Monroeville, and the Providence-Ripley aquifer at Greenville. Significant declines in the potentiometric surfaces of the other major aquifers are not apparent. Recharge areas for all major aquifers are susceptible to contamination, but the probability of contamination of the Lisbon, Nanafalia-Clayton, and Providence-Ripley aquifers is low because the recharge areas are remote from areas of the withdrawal. The depressions in the recharge area for the Upper Floridan aquifer and the area where the Pliocene-Miocene aquifer is overlain by the gravelly sands of the Citronelle Formation are highly susceptible to contamination from the surface. (USGS)

  8. Microbiology of the surface water samples in the high background radiation areas of Ramsar, Iran

    International Nuclear Information System (INIS)

    Motamedifar, Mohammad; Zamani, Khosrow; Sedigh, Hadi; Mortazavi, Seyed Mohammad Javad; Taeb, Shahram; Haghani, M.; Mortazavi, Seyed Ali Reza; Soofi, Amir

    2014-01-01

    Residents of high background radiation areas of Ramsar have lived in these areas for many generations and received radiation doses much higher than the dose limit recommended by ICRP for radiation workers. The radioactivity of the high background radiation areas of Ramsar is reported to be due to 226 Ra and its decay products, which have been brought to the surface by the waters of hot springs. Over the past years the department has focused on different aspects of the health effects of the elevated levels of natural radiation in Ramsar. This study was aimed to perform a preliminary investigation on the bioeffects of exposure to elevated levels of natural radiation on the microbiology of surface water samples. Water samples were collected from surface water streams in Talesh Mahalleh district, Ramsar as well as a nearby area with normal levels of background radiation. Only two strains of bacteria, that is, Providencia stuartii and Shimwellia blattae, could be isolated from the water samples collected from high background radiation areas, while seven strains (Escherichia coli, Enterobacter asburiae, Klebsiella pneumoniae, Shigella dysenteriae, Buttiauxella agerstis, Tatumella punctuata and Raoultella ornithinolytica) were isolated from the water samples collected from normal background radiation areas. All the bacteria isolated from water samples of high and normal background radiation areas were sensitive to ultraviolet radiation, heat, betadine, alcohol, and deconex. Although other investigators have reported that bacteria isolated from hot springs show radioresistance, the results reported here do not reveal any adaptive response. (author)

  9. The role of cell walls and pectins in cation exchange and surface area of plant roots.

    Science.gov (United States)

    Szatanik-Kloc, A; Szerement, J; Józefaciuk, G

    2017-08-01

    We aimed to assess role of cell walls in formation of cation exchange capacity, surface charge, surface acidity, specific surface, water adsorption energy and surface charge density of plant roots, and to find the input of the cell wall pectins to the above properties. Whole roots, isolated cell walls and the residue after the extraction of pectins from the cell walls of two Apiaceae L. species (celeriac and parsnip) were studied using potentiometric titration curves and water vapor adsorption - desorption isotherms. Total amount of surface charge, as well as the cation exchange capacity were markedly higher in roots than in their cell walls, suggesting large contribution of other cell organelles to the binding of cations by the whole root cells. Significantly lower charge of the residues after removal of pectins was noted indicating that pectins play the most important role in surface charge formation of cell walls. The specific surface was similar for all of the studied materials. For the separated cell walls it was around 10% smaller than of the whole roots, and it increased slightly after the removal of pectins. The surface charge density and water vapor adsorption energy were the highest for the whole roots and the lowest for the cell walls residues after removal of pectins. The results indicate that the cell walls and plasma membranes are jointly involved in root ion exchange and surface characteristics and their contribution depends upon the plant species. Copyright © 2017 Elsevier GmbH. All rights reserved.

  10. Strain-Dependent Solid Surface Stress and the Stiffness of Soft Contacts

    Directory of Open Access Journals (Sweden)

    Katharine E. Jensen

    2017-11-01

    Full Text Available Surface stresses have recently emerged as a key player in the mechanics of highly compliant solids. The classic theories of contact mechanics describe adhesion with a compliant substrate as a competition between surface energies driving deformation to establish contact and bulk elasticity resisting this. However, it has recently been shown that surface stresses provide an additional restoring force that can compete with and even dominate over elasticity in highly compliant materials, especially when length scales are small compared to the ratio of the surface stress to the elastic modulus, ϒ/E. Here, we investigate experimentally the contribution of surface stresses to the total force of adhesion. We find that the elastic and capillary contributions to the adhesive force are of similar magnitude and that both are required to account for measured adhesive forces between rigid silica spheres and compliant, silicone gels. Notably, the strain dependence of the solid surface stress contributes to the stiffness of soft solid contacts at leading order.

  11. A Three-Dimensional Enormous Surface Area Aluminum Microneedle Array with Nanoporous Structure

    OpenAIRE

    Chen, Po Chun; Hsieh, Sheng Jen; Chen, Chien Chon; Zou, Jun

    2013-01-01

    We proposed fabricating an aluminum microneedle array with a nanochannel structure on the surface by combining micromachining, electrolyte polishing, and anodization methods. The microneedle array provides a three-dimensional (3D) structure that possesses several hundred times more surface area than a traditional nanochannel template. Therefore, the microneedle array can potentially be used in many technology applications. This 3D microneedle array device can not only be used for painless inj...

  12. Area-averaged surface fluxes and their time-space variability over the FIFE experimental domain

    Science.gov (United States)

    Smith, E. A.; Hsu, A. Y.; Crosson, W. L.; Field, R. T.; Fritschen, L. J.; Gurney, R. J.; Kanemasu, E. T.; Kustas, W. P.; Nie, D.; Shuttleworth, W. J.

    1992-01-01

    The underlying mean and variance properties of surface net radiation, sensible-latent heat fluxes and soil heat flux are studied over the densely instrumented grassland region encompassing FIFE. Flux variability is discussed together with the problem of scaling up to area-averaged fluxes. Results are compared and contrasted for cloudy and clear situations and examined for the influence of surface-induced biophysical controls (burn and grazing treatments) and topographic controls (aspect ratios and slope factors).

  13. Temperature-dependent electronic decay profiles in CZT: probe of bulk and surface properties

    Science.gov (United States)

    Kessick, Royal; Maupin, Hugh; Tepper, Gary C.; Szeles, Csaba

    2003-01-01

    The electronic performance of CZT-based gamma radiation spectrometers is governed by a synergism of bulk and surface properties. Compensation is used to increase the bulk resistivity of Cd1-xZnxTe (x~0.1), but the same electronic states that are introduced to increase the material resistivity can also trap charge and reduce the carrier lifetime. Electrical and mechanical surface defects introduced during or subsequent to crystal harvesting are also known to interfere with device performance. Using a contactless, pulsed laser microwave cavity perturbation technique, electronic decay profiles were studied in high pressure Bridgman CZT as a function of temperature. The electronic decay profile was found to depend very strongly on temperature and was modeled using a function consisting of two exponential terms with temperature-dependent amplitudes and time constants. The model was used to relate the observed temperature dependent decay kinetics in CZT to specific trap energies. It was found that, at low temperatures, the electronic decay process is dominated by a deep trap with an energy of approximately 0.69 +/- 0.1 eV from the band edge. As the temperature is increased, the charge trapping becomes dominated by a second trap with an energy of approximately 0.60 +/- 0.1 eV from the band edge. Surface damage introduces additional charge traps that significantly alter the decay kinetics particularly at low temperatures.

  14. DMSA scan nomograms for renal length and area: Related to patient age and to body weight, height or surface area

    International Nuclear Information System (INIS)

    Hassan, I.M.; Que, L.; Rutland, M.D.

    2002-01-01

    Aim: To create nomograms for renal size as measured from DMSA renal studies, and to test the nomograms for their ability to separate normal from abnormal kidneys. Method: Renal length was measured from posterior oblique views and renal area from posterior views. Results from 253 patients with bilateral normal kidneys were used to create nomograms for renal size relative to patient age, body height, weight or body surface area (BSA). The nomograms enclosed 95% of the normal kidneys, thus indicating the range for 95% confidence limits, and hence the specificity. Each nomogram was then tested against 46 hypertrophied kidneys and 46 damaged kidneys. Results: The results from nomograms of renal length and renal area, compared to age, body height, body weight and BSA are presented. For each nomogram, the range is presented as a fraction of the mean value, and the number of abnormal kidneys (hypertrophied or damaged) outside the normal range is presented as a percentage (indicating the sensitivity). Conclusion: Renal Area was no better than renal length for detecting abnormal kidneys. Patient age was the least useful method of normalisation. BSA normalisation produced the best results most frequently (narrower ranges and highest detection of abnormal kidneys)

  15. Heavy metal contamination in surface runoff sediments of the urban area of Vilnius, Lithuania

    Directory of Open Access Journals (Sweden)

    Gytautas Ignatavičius

    2017-02-01

    Full Text Available Surface runoff from urbanized territories carries a wide range of pollutants. Sediments in untreated runoff from direct discharge stormwater systems significantly contribute to urban waterway pollution. In this study, heavy metal (Pb, Zn, Cu, Cr, Ba, As and Fe contamination in surface runoff sediments of the urban area of the city of Vilnius was investigated. The surface runoff sediment samples were collected from seven dischargers with the highest volume rate of water flow and concentrations of suspended solids. The geospatial analysis of the distribution of heavy metals shows that there are several active pollution sources supplying the dischargers with contaminated sediments. Most of these areas are located in the central part of the city and in old town with intense traffic. Principal components analysis and t-test results clearly depicted the significantly different chemical compositions of winter and autumn surface sediment samples. The sampling approach and assessment of results provide a useful tool to examine the contamination that is generated in urban areas, distinguish pollution sources and give a better understanding of the importance of permeable surfaces and green areas.

  16. Direct Measurement of the Surface Energy of Bimetallic Nanoparticles: Evidence of Vegard's Rulelike Dependence

    Science.gov (United States)

    Chmielewski, Adrian; Nelayah, Jaysen; Amara, Hakim; Creuze, Jérôme; Alloyeau, Damien; Wang, Guillaume; Ricolleau, Christian

    2018-01-01

    We use in situ transmission electron microscopy to monitor in real time the evaporation of gold, copper, and bimetallic copper-gold nanoparticles at high temperature. Besides, we extend the Kelvin equation to two-component systems to predict the evaporation rates of spherical liquid mono- and bimetallic nanoparticles. By linking this macroscopic model to experimental TEM data, we determine the surface energies of pure gold, pure copper, Cu50 Au50 , and Cu25 Au75 nanoparticles in the liquid state. Our model suggests that the surface energy varies linearly with the composition in the liquid Cu-Au nanoalloy; i.e., it follows a Vegard's rulelike dependence. To get atomic-scale insights into the thermodynamic properties of Cu-Au alloys on the whole composition range, we perform Monte Carlo simulations employing N -body interatomic potentials. These simulations at a microscopic level confirm the Vegard's rulelike behavior of the surface energy obtained from experiments combined with macroscopic modeling.

  17. Surface chemistry of K-montmorillonite: ionic strength, temperature dependence and dissolution kinetics.

    Science.gov (United States)

    Rozalén, Marisa; Brady, Patrick V; Huertas, F Javier

    2009-05-15

    The surface chemistry of K-montmorillonite was investigated by potentiometric titrations conducted at 25, 50 and 70 degrees C and at ionic strengths of 0.001, 0.01 and 0.1 M KNO(3). Proton adsorption decreases with electrolyte concentration at all pHs. The pH of zero net proton charge (PZNPC) decreases from 8.1 to 7.6 when the ionic strength increases from 0.001 to 0.1 M. Temperature has a very small effect on surface charge. A constant capacitance model that accounts for protonation/deprotonation of aluminol and silanol edge sites and basal plane H(+)/K(+) exchange is used to fit the experimental data. H(+) and OH(-) adsorption to specific surface sites appear to account for the pH-dependence of the K-montmorillonite dissolution.

  18. Formulation of the Reynolds equation on a time-dependent lubrication surface

    Science.gov (United States)

    Stupkiewicz, S.

    2016-01-01

    The Reynolds equation, which describes the lubrication effect arising through the interaction of two physical surfaces that are separated by a thin fluid film, is formulated with respect to a continuously evolving third surface that is described by a time-dependent curvilinear coordinate system. The proposed formulation essentially addresses lubrication mechanics at interfaces undergoing large deformations and a priori satisfies all objectivity requirements, neither of which are features of the classical Reynolds equation. As such, this formulation may be particularly suitable for non-stationary elastohydrodynamic lubrication problems associated with soft interfaces. The ability of the formulation to capture finite-deformation effects and the influence of the choice of the third surface are illustrated through analytical examples. PMID:27118926

  19. Dye-Sensitized Solar Cells Based on High Surface Area Nanocrystalline Zinc Oxide Spheres

    Directory of Open Access Journals (Sweden)

    Pavuluri Srinivasu

    2011-01-01

    Full Text Available High surface area nanocrystalline zinc oxide material is fabricated using mesoporous nanostructured carbon as a sacrificial template through combustion process. The resulting material is characterized by XRD, N2 adsorption, HR-SEM, and HR-TEM. The nitrogen adsorption measurement indicates that the materials possess BET specific surface area ca. 30 m2/g. Electron microscopy images prove that the zinc oxide spheres possess particle size in the range of 0.12 μm–0.17 μm. The nanocrystalline zinc oxide spheres show 1.0% of energy conversion efficiency for dye-sensitized solar cells.

  20. Volumes, Masses, and Surface Areas for Shippingport LWBR Spent Nuclear Fuel in a DOE SNF Canister

    International Nuclear Information System (INIS)

    J.W. Davis

    1999-01-01

    The purpose of this calculation is to estimate volumes, masses, and surface areas associated with (a) an empty Department of Energy (DOE) 18-inch diameter, 15-ft long spent nuclear fuel (SNF) canister, (b) an empty DOE 24-inch diameter, 15-ft long SNF canister, (c) Shippingport Light Water Breeder Reactor (LWBR) SNF, and (d) the internal basket structure for the 18-in. canister that has been designed specifically to accommodate Seed fuel from the Shippingport LWBR. Estimates of volumes, masses, and surface areas are needed as input to structural, thermal, geochemical, nuclear criticality, and radiation shielding calculations to ensure the viability of the proposed disposal configuration

  1. A process to enhance the specific surface area and capacitance of hydrothermally reduced graphene oxide

    KAUST Repository

    Alazmi, Amira

    2016-08-26

    The impact of post-synthesis processing in reduced graphene oxide materials for supercapacitor electrodes has been analyzed. A comparative study of vacuum, freeze and critical point drying was carried out for hydrothermally reduced graphene oxide demonstrating that the optimization of the specific surface area and preservation of the porous network are critical to maximize its supercapacitance performance. As described below, using a supercritical fluid as the drying medium, unprecedented values of the specific surface area (364 m2 g−1) and supercapacitance (441 F g−1) for this class of materials have been achieved.

  2. N2-specific surface area of ZrO2-montmorillonite MK-10 synthesis

    International Nuclear Information System (INIS)

    Muzakky; Imam Proyogo

    2016-01-01

    A measurements of N 2 -specific surface area of ZrO 2 -montmorillonite MK-10 synthesis have been done. The purpose of this study is to observed the effect of calcination on the a specific surface area (SSA N2 -BET) of ZrO 2 -montmorillonite MK-10 synthesis. Calcination were carried out at a 200°C; 400°C and 700°C. While the observations were made with surface area analyzer (SAA) and transmission electron microscopy (TEM). The measurement results obtained that SSA N2 -BET ZrO 2 -MK-10 obtained at 214 m 2 g -1 for before calcination and 195 m 2 g -1 after calcination at 400°C. The effected of calcination temperature will cause more towards of multilayer system surface, but the distribution of pore volume becomes smaller. Result of visualization of ZrO 2 -MK-10 surface that by means of TEM showed before calcination are more transparent and has a pore more. While calcination at 400°C has a darker impression and became multilayer and have a larger volume. Synthesized of ZrO 2 -MK 10 that using the ethylene glycol precursor have SSA N2 -BET higher than using glycerol is 195.33 m 2 g -1 and more memorable surface of a solid compact and orderly. (author)

  3. Observation of contact area of bubbles with heating surface in pool boiling of water under microgravity

    International Nuclear Information System (INIS)

    Suzuki, K.; Kawamura, H.; Suzuki, M.; Takahashi, S.; Abe, Y.

    2003-01-01

    Burnout heat flux was measured in subcooled pool boiling of water under attached boiling bubbles on heating surface with bubble holding plate in ground experiment. A thin stainless flat plate was employed for heating surface. The experimental setup and the heating procedures were same as used in reduced gravity experiment performed by a parabolic flight of jet aircraft. Same burnout heat flux as in the reduced gravity was obtained by adjusting the clearance between the bubble holder and the heating surface. They were 100 ∝ 400 percent higher than the widely accepted existing theories. As extending heating time longer than the reduced gravity duration until burnout occurred, burnout heat flux decreased gradually and became a constant value calculated from the existing theories. In a result of observing contact area of boiling bubbles with transparent heating surface, the contact area was smaller in quick heating time than that in long time heating at same heat flux. The experimental results suggest in microgravity that liquid layer is remained between rapidly expanded bubbles and heating surface. In microgravity experiment by a drop shaft facility, contact area of bubbles with heating surface increased considerably at starting of microgravity. (orig.)

  4. City landscape changes effects on land surface temperature in Bucharest metropolitan area

    Science.gov (United States)

    Savastru, Dan M.; Zoran, Maria A.; Savastru, Roxana S.; Dida, Adrian I.

    2017-10-01

    This study investigated the influences of city land cover changes and extreme climate events on land surface temperature in relationship with several biophysical variables in Bucharest metropolitan area of Romania through satellite and in-situ monitoring data. Remote sensing data from IKONOS, Landsat TM/ETM+ and time series MODIS Terra/Aqua and NOAA AVHRR sensors have been used to assess urban land cover- temperature interactions over 2000 - 2016 period. Time series Thermal InfraRed (TIR) satellite remote sensing data in synergy with meteorological data (air temperatureAT, precipitations, wind, solar radiation, etc.) were applied mainly for analyzing land surface temperature (LST) pattern and its relationship with surface landscape characteristics, assessing urban heat island (UHI), and relating urban land cover temperatures (LST). The land surface temperature, a key parameter for urban thermal characteristics analysis, was also analyzed in relation with the Normalized Difference Vegetation Index (NDVI) at city level. Results show that in the metropolitan area ratio of impervious surface in Bucharest increased significantly during investigated period, the intensity of urban heat island and heat wave events being most significant. The correlation analyses revealed that, at the pixel-scale, LST and AT possessed a strong positive correlation with percent impervious surfaces and negative correlation with vegetation abundances at metropolitan scale respectively. The NDVI was significantly correlated with precipitation. The spatial average air temperatures in urban test areas rise with the expansion of the urban size.

  5. Description of surface systems. Preliminary site description Simpevarp sub area - Version 1.2

    International Nuclear Information System (INIS)

    Lindborg, Tobias

    2005-03-01

    Swedish Nuclear Fuel and Waste Management Co is currently conducting site characterisation in the Simpevarp area. The area is divided into two subareas, the Simpevarp and the Laxemar subarea. The two subareas are surrounded by a common regional model area, the Simpevarp area. This report describes both the regional area and the subareas. This report is an interim version (model version 1.2) of the description of the surface systems at the Simpevarp area, and should be seen as a background report to the site description of the Simpevarp area, version 1.2, SKB-R--05-08. The basis for this description is quality-assured field data available in the SKB SICADA and GIS databases, together with generic data from the literature. The Surface system, here defined as everything above the bedrock, comprises a number of separate disciplines (e.g. hydrology, geology, topography, oceanography and ecology). Each discipline has developed descriptions and models for a number of properties that together represent the site description. The current methodology for developing the surface system description and the integration to ecosystem models is documented in a methodology strategy report SKB-R--03-06. The procedures and guidelines given in that report were followed in this report. Compared with version 1.1 of the surface system description SKB-R--04-25, this report presents considerable additional features, especially in the ecosystem description (Chapter 4) and in the description of the surface hydrology (Section 3.4). A first attempt has also been made to connect the flow of matter (carbon) between the different ecosystems into an overall ecosystem model at a landscape level. A summarised version of this report is also presented in SKB-R--05-08 together with geological-, hydrogeological-, transport properties-, thermal properties-, rock mechanics- and hydrogeochemical descriptions

  6. Description of surface systems. Preliminary site description Simpevarp sub area - Version 1.2

    Energy Technology Data Exchange (ETDEWEB)

    Lindborg, Tobias (ed.)

    2005-03-01

    Swedish Nuclear Fuel and Waste Management Co is currently conducting site characterisation in the Simpevarp area. The area is divided into two subareas, the Simpevarp and the Laxemar subarea. The two subareas are surrounded by a common regional model area, the Simpevarp area. This report describes both the regional area and the subareas. This report is an interim version (model version 1.2) of the description of the surface systems at the Simpevarp area, and should be seen as a background report to the site description of the Simpevarp area, version 1.2, SKB-R--05-08. The basis for this description is quality-assured field data available in the SKB SICADA and GIS databases, together with generic data from the literature. The Surface system, here defined as everything above the bedrock, comprises a number of separate disciplines (e.g. hydrology, geology, topography, oceanography and ecology). Each discipline has developed descriptions and models for a number of properties that together represent the site description. The current methodology for developing the surface system description and the integration to ecosystem models is documented in a methodology strategy report SKB-R--03-06. The procedures and guidelines given in that report were followed in this report. Compared with version 1.1 of the surface system description SKB-R--04-25, this report presents considerable additional features, especially in the ecosystem description (Chapter 4) and in the description of the surface hydrology (Section 3.4). A first attempt has also been made to connect the flow of matter (carbon) between the different ecosystems into an overall ecosystem model at a landscape level. A summarised version of this report is also presented in SKB-R--05-08 together with geological-, hydrogeological-, transport properties-, thermal properties-, rock mechanics- and hydrogeochemical descriptions.

  7. Evaporation and wetted area of single droplets on waxy and hairy leaf surfaces.

    Science.gov (United States)

    Zhu, H; Yu, Y; Ozkan, H E; Derksen, R C; Krause, C R

    2008-01-01

    Understanding the evaporation of pesticide droplets and wetting of Leaf surfaces can increase foliar application efficiency and reduce pesticide use. Evaporation time and wetted area of single pesticide droplets on hairy and waxy geranium leaf surfaces were measured under the controlled conditions for five droplet sizes and three relative humidities. The sprays used to form droplets included water, a nonionic colloidal polymer drift retardant, an alkyl polyoxyethylene surfactant, and an insecticide. Adding the surfactant into spray mixtures greatly increased droplet wetted area on the surfaces while droplet evaporation time was greatly reduced. Adding the drift retardant into spray mixture slightly increased the droplet evaporation time and the wetted area. Also, droplets had Longer evaporation times on waxy leaves than on hairy leaves for all droplet diameters and all relative humidity conditions. Increasing relative humidity could increase the droplet evaporation time greatly but did not change the the wetted area. The droplet evaporation time and wetted area increased exponentially as the droplet size increased. Therefore, droplet size, surface characteristics of the target, relative humidity, and chemical composition of the spray mixtures (water alone, pesticide, additives) should be included as important factors that affect the efficacy and efficiency of pesticide applications.

  8. Surface effects of electrode-dependent switching behavior of resistive random-access memory

    KAUST Repository

    Ke, Jr Jian

    2016-09-26

    The surface effects of ZnO-based resistive random-access memory (ReRAM) were investigated using various electrodes. Pt electrodes were found to have better performance in terms of the device\\'s switching functionality. A thermodynamic model of the oxygen chemisorption process was proposed to explain this electrode-dependent switching behavior. The temperature-dependent switching voltage demonstrates that the ReRAM devices fabricated with Pt electrodes have a lower activation energy for the chemisorption process, resulting in a better resistive switching performance. These findings provide an in-depth understanding of electrode-dependent switching behaviors and can serve as design guidelines for future ReRAM devices.

  9. [Areas of contact in human humero-ulnar joints as a function of pressure, their connection through subchondral mineralization and joint surface morphology of the incisura trochlearis].

    Science.gov (United States)

    Eckstein, F; Löhe, F; Steinlechner, M; Müller-Gerbl, M; Putz, R

    1993-12-01

    Evaluation of the stress distribution in joints can be obtained directly from contact areas and pressure forces, and also indirectly from the functional adaptation of the connective tissues. Therefore 8 human humero-ulnar joints, fixed in formalin, were examined for size and position of contact areas (polyether casting/Vidas image analyser) and their dependence upon the joint forces (Zwick material testing machine). The distribution of subchondral mineralisation was assessed, using CT osteoabsorptiometry. Depending on the joint force, the contact areas increase from about 10% of the total surface (20 N) to approximately 60% (1280 N). With weak forces they are localised ventrally and dorsally in the joint, with more powerful forces they run together centrally. With a divided articular surface they join at about 160-640 N, with a continuous surface, at about 40-80 N. Divided joint surfaces show a bicentric mineralisation pattern of the subchondral bone with ventral and dorsal maxima. Continuous surfaces, on the other hand, usually show central maxima. Both the mineralisation pattern and the position of the contact areas suggest a physiological incongruity of the humero-ulnar joint surfaces, which vanishes with increasing pressure due to viscoelastic deformation of articular cartilage and subchondral bone. More marked incongruity is postulated for the divided surfaces than for the others. The consequent peripheral transmission of pressure seems to involve a functional principle, which, present in several human joints, leads to both optimal distribution of the stress and better nutrition of the articular cartilage.

  10. Tear-Film Evaporation Rate from Simultaneous Ocular-Surface Temperature and Tear-Breakup Area.

    Science.gov (United States)

    Dursch, Thomas J; Li, Wing; Taraz, Baseem; Lin, Meng C; Radke, Clayton J

    2018-01-01

    A corneal heat-transfer model is presented to quantify simultaneous measurements of fluorescein tear-breakup area (TBA) and ocular-surface temperature (OST). By accounting for disruption of the tear-film lipid layer (TFLL), we report evaporation rates through lipid-covered tear. The modified heat-transfer model provides new insights into evaporative dry eye. A quantitative analysis is presented to assess human aqueous tear evaporation rate (TER) through intact TFLLs from simultaneous in vivo measurement of time-dependent infrared OST and fluorescein TBA. We interpret simultaneous OST and TBA measurements using an extended heat-transfer model. We hypothesize that TBAs are ineffectively insulated by the TFLL and therefore exhibit higher TER than does that for a well-insulting TFLL-covered tear. As time proceeds, TBAs increase in number and size, thereby increasing the cornea area-averaged TER and decreasing OST. Tear-breakup areas were assessed from image analysis of fluorescein tear-film-breakup video recordings and are included in the heat-transfer description of OST. Model-predicted OSTs agree well with clinical experiments. Percent reductions in TER of lipid-covered tear range from 50 to 95% of that for pure water, in good agreement with literature. The physical picture of noninsulating or ruptured TFLL spots followed by enhanced evaporation from underlying cooler tear-film ruptures is consistent with the evaporative-driven mechanism for local tear rupture. A quantitative analysis is presented of in vivo TER from simultaneous clinical measurement of transient OST and TBA. The new heat-transfer model accounts for increased TER through expanding TBAs. Tear evaporation rate varies strongly across the cornea because lipid is effectively missing over tear-rupture troughs. The result is local faster evaporation compared with nonruptured, thick lipid-covered tear. Evaporative-driven tear-film ruptures deepen to a thickness where fluorescein quenching commences and local

  11. Transparent self-cleaning lubricant-infused surfaces made with large-area breath figure patterns

    Science.gov (United States)

    Zhang, Pengfei; Chen, Huawei; Zhang, Liwen; Ran, Tong; Zhang, Deyuan

    2015-11-01

    Nepenthes pitcher inspired slippery lubricant-infused porous surfaces greatly impact the understanding of liquid-repellent surfaces construction and have attracted extensive attention in recent years due to their potential applications in self-cleaning, anti-fouling, anti-icing, etc. In this work, we have successfully fabricated transparent slippery lubricant-infused surfaces based on breath figure patterns (BFPs). Large-area BFPs with interconnected pores were initially formed on the glass substrate and then a suitable lubricant was added onto the surfaces. The interconnected pores in BFPs were able to hold the lubricant liquid in place and form a stable liquid/solid composite surface capable of repelling a variety of liquids. The liquid-repellent surfaces show extremely low critical sliding angles for various liquids, thus providing the surfaces with efficient self-cleaning property. It was also found that the liquid droplets' sliding behaviors on the surfaces were significantly influenced by the tilting angle of the substrate, liquid volume, liquid chemical properties, and pore sizes of the surfaces.

  12. Theoretical research of some parameters of contact area of wheel cutting surface and workpiece at flat face grinding with preliminary inclination of spindle axis

    OpenAIRE

    I. N. Pyzhov; V. G. Klimenko

    2016-01-01

    Theoretical researches that have made it possible to obtain the analytical dependences connecting the parameters of contact area of wheel cutting surface such as length, width, arc length, form deviation of flat surface and workpiece under conditions of flat face grinding with preliminary inclination of spindle axis have been carried out. The paper shows the role of the angle of preliminary inclination of spindle axis, grinding depth and the wheel diameter in the grinding process. It allows c...

  13. Surface area and the seabed area, volume, depth, slope, and topographic variation for the world's seas, oceans, and countries.

    Science.gov (United States)

    Costello, Mark John; Cheung, Alan; De Hauwere, Nathalie

    2010-12-01

    Depth and topography directly and indirectly influence most ocean environmental conditions, including light penetration and photosynthesis, sedimentation, current movements and stratification, and thus temperature and oxygen gradients. These parameters are thus likely to influence species distribution patterns and productivity in the oceans. They may be considered the foundation for any standardized classification of ocean ecosystems and important correlates of metrics of biodiversity (e.g., species richness and composition, fisheries). While statistics on ocean depth and topography are often quoted, how they were derived is rarely cited, and unless calculated using the same spatial resolution the resulting statistics will not be strictly comparable. We provide such statistics using the best available resolution (1-min) global bathymetry, and open source digital maps of the world's seas and oceans and countries' Exclusive Economic Zones, using a standardized methodology. We created a terrain map and calculated sea surface and seabed area, volume, and mean, standard deviation, maximum, and minimum, of both depth and slope. All the source data and our database are freely available online. We found that although the ocean is flat, and up to 71% of the area has a ocean volume exceeds 1.3 billion km(3) (or 1.3 sextillion liters), and sea surface and seabed areas over 354 million km(2). We propose the coefficient of variation of slope as an index of topographic heterogeneity. Future studies may improve on this database, for example by using a more detailed bathymetry, and in situ measured data. The database could be used to classify ocean features, such as abyssal plains, ridges, and slopes, and thus provide the basis for a standards based classification of ocean topography.

  14. Time Dependent Frictional Changes in Ice due to Contact Area Changes

    Science.gov (United States)

    Sevostianov, V.; Lipovsky, B. P.; Rubinstein, S.; Dillavou, S.

    2017-12-01

    Sliding processes along the ice-bed interface of Earth's great ice sheets are the largest contributor to our uncertainty in future sea level rise. Laboratory experiments that have probed sliding processes have ubiquitously shown that ice-rock interfaces strengthen while in stationary contact (Schulson and Fortt, 2013; Zoet et al., 2013; McCarthy et al., 2017). This so-called frictional ageing effect may have profound consequences for ice sheet dynamics because it introduces the possibility of basal strength hysteresis. Furthermore this effect is quite strong in ice-rock interfaces (more than an order of magnitude more pronounced than in rock-rock sliding) and can double in frictional strength in a matter of minutes, much faster than most frictional aging (Dieterich, 1972; Baumberger and Caroli, 2006). Despite this importance, the underling physics of frictional ageing of ice remain poorly understood. Here we conduct laboratory experiments to image the microscopic points of contact along an ice-glass interface. We optically measure changes in the real area of contact over time using measurements of this reflected optical light intensity. We show that contact area increases with time of stationary contact. This result suggests that thermally enhanced creep of microscopic icy contacts is responsible for the much larger frictional ageing observed in ice-rock versus rock-rock interfaces. Furthermore, this supports a more physically detailed description of the thermal dependence of basal sliding than that used in the current generation of large scale ice sheet models.

  15. Vividness of Visual Imagery Depends on the Neural Overlap with Perception in Visual Areas.

    Science.gov (United States)

    Dijkstra, Nadine; Bosch, Sander E; van Gerven, Marcel A J

    2017-02-01

    Research into the neural correlates of individual differences in imagery vividness point to an important role of the early visual cortex. However, there is also great fluctuation of vividness within individuals, such that only looking at differences between people necessarily obscures the picture. In this study, we show that variation in moment-to-moment experienced vividness of visual imagery, within human subjects, depends on the activity of a large network of brain areas, including frontal, parietal, and visual areas. Furthermore, using a novel multivariate analysis technique, we show that the neural overlap between imagery and perception in the entire visual system correlates with experienced imagery vividness. This shows that the neural basis of imagery vividness is much more complicated than studies of individual differences seemed to suggest. Visual imagery is the ability to visualize objects that are not in our direct line of sight: something that is important for memory, spatial reasoning, and many other tasks. It is known that the better people are at visual imagery, the better they can perform these tasks. However, the neural correlates of moment-to-moment variation in visual imagery remain unclear. In this study, we show that the more the neural response during imagery is similar to the neural response during perception, the more vivid or perception-like the imagery experience is. Copyright © 2017 the authors 0270-6474/17/371367-07$15.00/0.

  16. Using lagged dependence to identify (de)coupled surface and subsurface soil moisture values

    Science.gov (United States)

    Carranza, Coleen D. U.; van der Ploeg, Martine J.; Torfs, Paul J. J. F.

    2018-04-01

    Recent advances in radar remote sensing popularized the mapping of surface soil moisture at different spatial scales. Surface soil moisture measurements are used in combination with hydrological models to determine subsurface soil moisture values. However, variability of soil moisture across the soil column is important for estimating depth-integrated values, as decoupling between surface and subsurface can occur. In this study, we employ new methods to investigate the occurrence of (de)coupling between surface and subsurface soil moisture. Using time series datasets, lagged dependence was incorporated in assessing (de)coupling with the idea that surface soil moisture conditions will be reflected at the subsurface after a certain delay. The main approach involves the application of a distributed-lag nonlinear model (DLNM) to simultaneously represent both the functional relation and the lag structure in the time series. The results of an exploratory analysis using residuals from a fitted loess function serve as a posteriori information to determine (de)coupled values. Both methods allow for a range of (de)coupled soil moisture values to be quantified. Results provide new insights into the decoupled range as its occurrence among the sites investigated is not limited to dry conditions.

  17. Size dependence of volume and surface nucleation rates for homogeneous freezing of supercooled water droplets

    Directory of Open Access Journals (Sweden)

    T. Kuhn

    2011-03-01

    Full Text Available The relative roles of volume and surface nucleation were investigated for the homogeneous freezing of pure water droplets. Experiments were carried out in a cryogenic laminar aerosol flow tube using supercooled water aerosols with maximum volume densities at radii between 1 and 3 μm. Temperature- and size-dependent values of volume- and surface-based homogeneous nucleation rates between 234.8 and 236.2 K were derived using a microphysical model and aerosol phase compositions and size distributions determined from infrared extinction measurements in the flow tube. The results show that the contribution from nucleation at the droplet surface increases with decreasing droplet radius and dominates over nucleation in the bulk droplet volume for droplets with radii smaller than approximately 5 μm. This is interpreted in terms of a lowered free energy of ice germ formation in the surface-based process. The implications of surface nucleation for the parameterization of homogeneous ice nucleation in numerical models are considered.

  18. Orientation-dependent chemistry and band-bending of Ti on polar ZnO surfaces.

    Science.gov (United States)

    Borghetti, Patrizia; Mouchaal, Younes; Dai, Zongbei; Cabailh, Gregory; Chenot, Stéphane; Lazzari, Rémi; Jupille, Jacques

    2017-04-19

    Orientation-dependent reactivity and band-bending are evidenced upon Ti deposition (1-10 Å) on polar ZnO(0001)-Zn and ZnO(0001[combining macron])-O surfaces. At the onset of the Ti deposition, a downward band-bending was observed on ZnO(0001[combining macron])-O while no change occurred on ZnO(0001)-Zn. Combining this with the photoemission analysis of the Ti 2p core level and Zn L 3 (L 2 )M 45 M 45 Auger transition, it is established that the Ti/ZnO reaction is of the form Ti + 2ZnO → TiO 2 + 2Zn on ZnO(0001)-Zn and Ti + yZnO → TiZn x O y + (y - x)Zn on ZnO(0001[combining macron])-O. Consistently, upon annealing thicker Ti adlayers, the metallic zinc is removed to leave ZnO(0001)-Zn surfaces covered with a TiO 2 -like phase and ZnO(0001[combining macron])-O surfaces covered with a defined (Ti, Zn, O) compound. Finally, a difference in the activation temperature between the O-terminated (500 K) and Zn-terminated (700 K) surfaces is observed, which is tentatively explained by different electric fields in the space charge layer at ZnO surfaces.

  19. Snow specific surface area simulation using the one-layer snow model in the Canadian LAnd Surface Scheme (CLASS

    Directory of Open Access Journals (Sweden)

    A. Roy

    2013-06-01

    Full Text Available Snow grain size is a key parameter for modeling microwave snow emission properties and the surface energy balance because of its influence on the snow albedo, thermal conductivity and diffusivity. A model of the specific surface area (SSA of snow was implemented in the one-layer snow model in the Canadian LAnd Surface Scheme (CLASS version 3.4. This offline multilayer model (CLASS-SSA simulates the decrease of SSA based on snow age, snow temperature and the temperature gradient under dry snow conditions, while it considers the liquid water content of the snowpack for wet snow metamorphism. We compare the model with ground-based measurements from several sites (alpine, arctic and subarctic with different types of snow. The model provides simulated SSA in good agreement with measurements with an overall point-to-point comparison RMSE of 8.0 m2 kg–1, and a root mean square error (RMSE of 5.1 m2 kg–1 for the snowpack average SSA. The model, however, is limited under wet conditions due to the single-layer nature of the CLASS model, leading to a single liquid water content value for the whole snowpack. The SSA simulations are of great interest for satellite passive microwave brightness temperature assimilations, snow mass balance retrievals and surface energy balance calculations with associated climate feedbacks.

  20. Impact of microstructure evolution on the difference between geometric and reactive surface areas in natural chalk

    Science.gov (United States)

    Yang, Y.; Bruns, S.; Stipp, S. L. S.; Sørensen, H. O.

    2018-05-01

    The coupling between flow and mineral dissolution drives the evolution of many natural and engineered flow systems. Pore surface changes as microstructure evolves but this transient behaviour has traditionally been difficult to model. We combined a reactor network model with experimental, greyscale tomography data to establish the morphological grounds for differences among geometric, reactive and apparent surface areas in dissolving chalk. This approach allowed us to study the effects of initial geometry and macroscopic flow rate independently. The simulations showed that geometric surface, which represents a form of local transport heterogeneity, increases in an imposed flow field, even when the porous structure is chemically homogeneous. Hence, the fluid-reaction coupling leads to solid channelisation, which further results in fluid focusing and an increase in geometric surface area. Fluid focusing decreases the area of reactive surface and the residence time of reactant, both contribute to the over-normalisation of reaction rate. In addition, the growing and merging of microchannels, near the fluid entrance, contribute to the macroscopic, fast initial dissolution rate of rocks.

  1. Ambient pressure dried tetrapropoxysilane-based silica aerogels with high specific surface area

    Science.gov (United States)

    Parale, Vinayak G.; Han, Wooje; Jung, Hae-Noo-Ree; Lee, Kyu-Yeon; Park, Hyung-Ho

    2018-01-01

    In the present paper, we report the synthesis of tetrapropoxysilane (TPOS)-based silica aerogels with high surface area and large pore volume. The silica aerogels were prepared by a two-step sol-gel process followed by surface modification via a simple ambient pressure drying approach. In order to minimize drying shrinkage and obtain hydrophobic aerogels, the surface of the alcogels was modified using trichloromethylsilane as a silylating agent. The effect of the sol-gel compositional parameters on the polymerization of aerogels prepared by TPOS, one of the precursors belonging to the Si(OR)4 family, was reported for the first time. The oxalic acid and NH4OH concentrations were adjusted to achieve good-quality aerogels with high surface area, low density, and high transparency. Controlling the hydrolysis and condensation reactions of the TPOS precursor turned out to be the most important factor to determine the pore characteristics of the aerogel. Highly transparent aerogels with high specific surface area (938 m2/g) and low density (0.047 g/cm3) could be obtained using an optimized TPOS/MeOH molar ratio with appropriate concentrations of oxalic acid and NH4OH.

  2. State-dependent errors in a land surface model across biomes inferred from eddy covariance observations on multiple timescales

    NARCIS (Netherlands)

    Wang, T.; Brender, P.; Ciais, P.; Piao, S.; Mahecha, M.D.; Chevallier, F.; Reichstein, M.; Ottle, C.; Maignan, F.; Arain, A.; Bohrer, G.; Cescatti, A.; Kiely, G.; Law, B.E.; Lutz, M.; Montagnani, L.; Moors, E.J.

    2012-01-01

    Characterization of state-dependent model biases in land surface models can highlight model deficiencies, and provide new insights into model development. In this study, artificial neural networks (ANNs) are used to estimate the state-dependent biases of a land surface model (ORCHIDEE: ORganising

  3. Quality of surface-water supplies in the Triangle area of North Carolina, water year 2008

    Science.gov (United States)

    Giorgino, M.J.; Rasmussen, R.B.; Pfeifle, C.A.

    2012-01-01

    Surface-water supplies are important sources of drinking water for residents in the Triangle area of North Carolina, which is located within the upper Cape Fear and Neuse River Basins. Since 1988, the U.S. Geological Survey and a consortium of governments have tracked water-quality conditions and trends in several of the area's water-supply lakes and streams. This report summarizes data collected through this cooperative effort, known as the Triangle Area Water Supply Monitoring Project, during October 2007 through September 2008. Major findings for this period include:

  4. Surface feature congruency effects in the object-reviewing paradigm are dependent on task memory demands.

    Science.gov (United States)

    Kimchi, Ruth; Pirkner, Yossef

    2014-08-01

    Perception of object continuity depends on establishing correspondence between objects viewed across disruptions in visual information. The role of spatiotemporal information in guiding object continuity is well documented; the role of surface features, however, is controversial. Some researchers have shown an object-specific preview benefit (OSPB)-a standard index of object continuity-only when correspondence could be based on an object's spatiotemporal information, whereas others have found color-based OSPB, suggesting that surface features can also guide object continuity. This study shows that surface feature-based OSPB is dependent on the task memory demands. When the task involved letters and matching just one target letter to the preview ones, no color congruency effect was found under spatiotemporal discontinuity and spatiotemporal ambiguity (Experiments 1-3), indicating that the absence of feature-based OSPB cannot be accounted for by salient spatiotemporal discontinuity. When the task involved complex shapes and matching two target shapes to the preview ones, color-based OSPB was obtained. Critically, however, when a visual working memory task was performed concurrently with the matching task, the presence of a nonspatial (but not a spatial) working memory load eliminated the color-based OSPB (Experiments 4 and 5). These results suggest that the surface feature congruency effects that are observed in the object-reviewing paradigm (with the matching task) reflect memory-based strategies that participants use to solve a memory-demanding task; therefore, they are not reliable measures of online object continuity and cannot be taken as evidence for the role of surface features in establishing object correspondence.

  5. Minimal area surfaces dual to Wilson loops and the Mathieu equation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Changyu; He, Yifei; Kruczenski, Martin [Department of Physics and Astronomy, Purdue University, 525 Northwestern Avenue, W. Lafayette, IN, 47907-2036 (United States)

    2016-08-11

    The AdS/CFT correspondence relates Wilson loops in N=4 SYM to minimal area surfaces in AdS{sub 5}×S{sup 5} space. Recently, a new approach to study minimal area surfaces in AdS{sub 3}⊂AdS{sub 5} was discussed based on a Schroedinger equation with a periodic potential determined by the Schwarzian derivative of the shape of the Wilson loop. Here we use the Mathieu equation, a standard example of a periodic potential, to obtain a class of Wilson loops such that the area of the dual minimal area surface can be computed analytically in terms of eigenvalues of such equation. As opposed to previous examples, these minimal surfaces have an umbilical point (where the principal curvatures are equal) and are invariant under λ-deformations. In various limits they reduce to the single and multiple wound circular Wilson loop and to the regular light-like polygons studied by Alday and Maldacena. In this last limit, the periodic potential becomes a series of deep wells each related to a light-like segment. Small corrections are described by a tight-binding approximation. In the circular limit they are well approximated by an expansion developed by A. Dekel. In the particular case of no umbilical points they reduce to a previous solution proposed by J. Toledo. The construction works both in Euclidean and Minkowski signature of AdS{sub 3}.

  6. Minimal area surfaces dual to Wilson loops and the Mathieu equation

    Science.gov (United States)

    Huang, Changyu; He, Yifei; Kruczenski, Martin

    2016-08-01

    The AdS/CFT correspondence relates Wilson loops in {N}=4 SYM to minimal area surfaces in AdS 5 × S 5 space. Recently, a new approach to study minimal area surfaces in AdS 3 ⊂ AdS 5 was discussed based on a Schroedinger equation with a periodic potential determined by the Schwarzian derivative of the shape of the Wilson loop. Here we use the Mathieu equation, a standard example of a periodic potential, to obtain a class of Wilson loops such that the area of the dual minimal area surface can be computed analytically in terms of eigenvalues of such equation. As opposed to previous examples, these minimal surfaces have an umbilical point (where the principal curvatures are equal) and are invariant under λ-deformations. In various limits they reduce to the single and multiple wound circular Wilson loop and to the regular light-like polygons studied by Alday and Maldacena. In this last limit, the periodic potential becomes a series of deep wells each related to a light-like segment. Small corrections are described by a tight-binding approximation. In the circular limit they are well approximated by an expansion developed by A. Dekel. In the particular case of no umbilical points they reduce to a previous solution proposed by J. Toledo. The construction works both in Euclidean and Minkowski signature of AdS 3.

  7. Lp-dual affine surface area forms of Busemann–Petty type problems

    Indian Academy of Sciences (India)

    (Math. Sci.) Vol. 125, No. 1, February 2015, pp. 71–77. c Indian Academy of Sciences. Lp-dual affine surface area forms of Busemann–Petty type problems ..... problem in three dimensions,. Ann. Math. 140(2) (1994) 435–447. [4] Gardner R J, Geometric tomography, 2nd edn (2006) (Cambridge, UK: Cambridge Univ. Press).

  8. Specific surface area behavior of a dissolving population of particles. Augmenting Mercer Dissolution Theory

    International Nuclear Information System (INIS)

    Scripsick, R.C.; Rothenberg, S.J.

    1986-01-01

    Specific surface area (Sp) measurements were made on two uranium oxide aerosol materials before and after in vitro dissolution studies were performed on the materials. The results of these Sp measurements were evaluated relative to predictions made from extending Mercer dissolution theory to describe the Sp behavior of a dissolving population of particles

  9. Area densitometry using rotating Scheimpflug photography for posterior capsule opacification and surface light scattering analyses.

    Science.gov (United States)

    Minami, Keiichiro; Honbo, Masato; Mori, Yosai; Kataoka, Yasushi; Miyata, Kazunori

    2015-11-01

    To compare area densitometry analysis using rotating Scheimpflug photography in quantifications of posterior capsule opacification (PCO) and surface light scattering with previous anterior-segment analyzer measurement. Miyata Eye Hospital, Miyazaki, Japan. Prospective observational case series. Scheimpflug images of eyes with foldable intraocular lenses (IOLs) were obtained using rotating and fixed Scheimpflug photography. Area densitometry on the posterior and anterior surfaces was conducted for PCO and surface light scattering analyses, respectively, with an identical area size. Correlation between two measurements was analyzed using linear regression. The study included 105 eyes of 74 patients who received IOLs 1 to 18 years (mean, 4.9 ± 4.5 years) postoperatively. In the PCO analysis on the posterior IOL surface, there was a significant correlation between the two measurements (P photography exhibited saturation due to intensive scatterings. Area densitometry combined with a rotating Scheimpflug photography was exchangeable to previously established densitometry measurement, and allowed successive evaluation in longer-term observations. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  10. Characterization of pigment-leached antifouling coatings using BET surface area measurements and mercury porosimetry

    DEFF Research Database (Denmark)

    Kiil, Søren; Dam-Johansen, Kim

    2007-01-01

    In this work BET surface area measurements and mercury porosimetry are used to characterize leached layers formed when seawater-soluble pigments (Cu2O and ZnO) dissolve during accelerated leaching of simple antifouling coatings. Measurements on single-pigment coatings show that an increasing...

  11. Surface area of lactose and lactose granulates on consolidation and compaction

    NARCIS (Netherlands)

    Riepma, Klaas Alouis

    1993-01-01

    This dissertation discusses the effect of short time storage at different conditions on the strength and the specific BET surface area of lactose tablets. In addition, some aspects are studied of the consolidation and compaction properties of crystalline lactose fractions in heterogeneous systems.

  12. Dose banding as an alternative to body surface area-based dosing of chemotherapeutic agents

    NARCIS (Netherlands)

    E. Chatelut (Etienne); M.L. White-Koning (M.); A.H.J. Mathijssen (Ron); F. Puisset (F.); S.D. Baker (Sharyn); A. Sparreboom (Alex)

    2012-01-01

    textabstractBackground: Dose banding is a recently suggested dosing method that uses predefined ranges (bands) of body surface area (BSA) to calculate each patients dose by using a single BSA-value per band. Thus, drugs with sufficient long-term stability can be prepared in advance. The main

  13. High surface area carbon for bifunctional air electrodes applied in zinc-air batteries

    Energy Technology Data Exchange (ETDEWEB)

    Arai, H. [on leave from NTT Laboratories (Japan); Mueller, S.; Haas, O. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Bifunctional air electrodes with high surface area carbon substrates showed low reduction overpotential, thus are promising for enhancing the energy efficiency and power capability of zinc-air batteries. The improved performance is attributed to lower overpotential due to diffusion of the reaction intermediate, namely the peroxide ion. (author) 1 fig., 2 refs.

  14. A method for increasing the surface area of perovskite-type oxides

    Indian Academy of Sciences (India)

    combustion of methane at different temperatures (450–600oC) has been thoroughly investigated. The hydrothermal treatments result in the activation of the perovskite oxides by increasing their surface area very markedly. Keywords. ABO3-type perovskite oxides; LaCoO3; LaMnO3; hydrothermal treatment; catalytic ...

  15. Should blood flow during cardiopulmonary bypass be individualized more than to body surface area?

    DEFF Research Database (Denmark)

    Thomassen, Sisse Anette; Larsson, A; Andreasen, Jan Jesper

    Blood flow during cardiopulmonary bypass (CPB) is calculated on body surface area (BSA). Increasing comorbidity, age and weight of today's cardiac patients question this calculation as it may not reflect individual metabolic requirement. The hypothesis was that a measured cardiac index (CI) prior...... not improve cerebral and systemic oxygenation compared to a blood flow based on BSA....

  16. Mapping surface flow in low gradient areas with thermal remote sensing

    DEFF Research Database (Denmark)

    Prinds, Christian; Petersen, Rasmus Jes; Greve, Mogens Humlekrog

    Thermal infrared (TIR) imagery has long been used for mapping groundwater-surface water interactions and mainly for locating areas of groundwater seepage in lakes and shorelines (Rundquist et al. 1985, Banks et al. 1996). In this study, we used the method for locating discharge from tile drains...

  17. Amylolytic hydrolysis of native starch granules affected by granule surface area.

    Science.gov (United States)

    Kim, J C; Kong, B W; Kim, M J; Lee, S H

    2008-11-01

    Initial stage of hydrolysis of native starch granules with various amylolytic enzymes, alpha-amylase from Bacillus subtilis, glucoamylase I (GA-I) and II (GA-II) from Aspergillus niger, and beta-amylase from sweet potato showed that the reaction was apparently affected by a specific surface area of the starch granules. The ratios of the reciprocal of initial velocity of each amylolytic hydrolysis for native potato and maize starch to that for rice with the amylolytic enzymes were nearly equivalent to the ratio of surface area per mass of the 2 starch granules to that of rice, that is, 6.94 and 2.25, respectively. Thus, the reciprocal of initial velocity of each enzymatic hydrolysis as expressed in a Lineweaver-Burk plot was a linear function of the reciprocal of surface area for each starch granule. As a result, it is concluded that amylolytic hydrolysis of native starch granules is governed by the specific surface area, not by the mass concentration, of each granule.

  18. Specific surface area effect on adsorption of chlorpyrifos and TCP by soils and modeling

    Science.gov (United States)

    The adsorption of chlorpyrifos and TCP (3,5,6, trichloro-2-pyridinol) was determined in four soils (Mollisol, Inceptisol, Entisol, Alfisol) having different specific surface areas (19–84 m2/g) but rather similar organic matter content (2.4–3.5%). Adsorption isotherms were derived from batch equilibr...

  19. Preparation of MgO Catalytic Support in Shaped Mesoporous High Surface Area Form

    Czech Academy of Sciences Publication Activity Database

    Gulková, Daniela; Šolcová, Olga; Zdražil, Miroslav

    2004-01-01

    Roč. 76, 1-3 (2004), s. 137-149 ISSN 1387-1811 R&D Projects: GA AV ČR IAA4072306 Institutional research plan: CEZ:AV0Z4072921 Keywords : MgO support * sigh Surface area * texture Subject RIV: CC - Organic Chemistry Impact factor: 2.093, year: 2004

  20. Thermal stability of porous sol-gel phosphosilicates and their surface area stabilisation by lanthanum addition

    NARCIS (Netherlands)

    Falco, Lorena; De Mendonca, Mariana Van Den Tempel; Mercadal, Juan J.; Zarubina, Valeriya; Melián-Cabrera, Ignacio

    2016-01-01

    The thermal stability of porous sol-gel phosphosilicates was studied by comparing the textural features upon calcination between 400 and 550 °C. A significant loss of surface area and pore volume were observed; the first is due to thermal coarsening of the nanoparticles, and the pore volume

  1. Allometric relationships for surface area and dry mass of young Norway spruce aboveground organs

    Czech Academy of Sciences Publication Activity Database

    Pokorný, Radek; Tomášková, Ivana

    53 2007, č. 12 (2007), s. 548-554 ISSN 1212-4834 R&D Projects: GA MŽP(CZ) SP/2D1/93/07 Institutional research plan: CEZ:AV0Z60870520 Keywords : allometry * biomass, * Picea abies * sapwood * surface area Subject RIV: GK - Forestry

  2. Estimating the surface area of non-convex particles from central planar sections

    DEFF Research Database (Denmark)

    Thórisdóttir, Ólöf; H.Rafati, Ali; Kiderlen, Markus

    . The Morse type estimator is well suited for computer assisted confocal microscopy and we demonstrate its practicability in a biological application: the surface area estimation of the nuclei of giant-cell glioblastoma from microscopy images. We also present an interactive software that allows the user...

  3. Flow analysis of water-powder mixtures: Application to specific surface area and shape factor

    NARCIS (Netherlands)

    Hunger, Martin; Brouwers, Jos

    2009-01-01

    This paper addresses the characterization of powder materials with respect to their application in concrete. Given that powders provide by far highest percentage of specific surface area in a concrete mix, their packing behavior and water demand is of vital interest for the design of concrete. They

  4. Turbostratic boron nitride coated on high-surface area metal oxide templates

    DEFF Research Database (Denmark)

    Klitgaard, Søren Kegnæs; Egeblad, Kresten; Brorson, M.

    2007-01-01

    Boron nitride coatings on high-surface area MgAl2O4 and Al2O3 have been synthesized and characterized by transmission electron microscopy and by X-ray powder diffraction. The metal oxide templates were coated with boron nitride using a simple nitridation in a flow of ammonia starting from ammonium...

  5. Condensation-Enhanced Self-Assembly as a Route to High Surface Area alpha-Aluminas

    NARCIS (Netherlands)

    Perez, Lidia Lopez; Zarubina, Valeriya; Heeres, Hero Jan; Melian-Cabrera, Ignacio

    2013-01-01

    High surface area nanosized alpha-alumina has been obtained by thermally treating a sol-gel-derived mesophase at 1200 degrees C; the mesophase was synthesized by a sol-gel route involving evaporation induced self-assembly (EISA) of a hydrolyzed gel from Al-tri-sec-butoxide in s-BuOH in the presence

  6. Strong and tough cellulose nanopaper with high specific surface area and porosity.

    Science.gov (United States)

    Sehaqui, Houssine; Zhou, Qi; Ikkala, Olli; Berglund, Lars A

    2011-10-10

    In order to better understand nanostructured fiber networks, effects from high specific surface area of nanofibers are important to explore. For cellulose networks, this has so far only been achieved in nonfibrous regenerated cellulose aerogels. Here, nanofibrillated cellulose (NFC) is used to prepare high surface area nanopaper structures, and the mechanical properties are measured in tensile tests. The water in NFC hydrogels is exchanged to liquid CO2, supercritical CO2, and tert-butanol, followed by evaporation, supercritical drying, and sublimation, respectively. The porosity range is 40-86%. The nanofiber network structure in nanopaper is characterized by FE-SEM and nitrogen adsorption, and specific surface area is determined. High-porosity TEMPO-oxidized NFC nanopaper (56% porosity) prepared by critical point drying has a specific surface area as high as 482 m(2) g(-1). The mechanical properties of this nanopaper structure are better than for many thermoplastics, but at a significantly lower density of only 640 kg m(-3). The modulus is 1.4 GPa, tensile strength 84 MPa, and strain-to-failure 17%. Compared with water-dried nanopaper, the material is softer with substantiallly different deformation behavior.

  7. Escaping the correction for body surface area when calculating glomerular filtration rate in children

    Energy Technology Data Exchange (ETDEWEB)

    Piepsz, Amy; Tondeur, Marianne [CHU St. Pierre, Department of Radioisotopes, Brussels (Belgium); Ham, Hamphrey [University Hospital Ghent, Department of Nuclear Medicine, Ghent (Belgium)

    2008-09-15

    {sup 51}Cr ethylene diamine tetraacetic acid ({sup 51}Cr EDTA) clearance is nowadays considered as an accurate and reproducible method for measuring glomerular filtration rate (GFR) in children. Normal values in function of age, corrected for body surface area, have been recently updated. However, much criticism has been expressed about the validity of body surface area correction. The aim of the present paper was to present the normal GFR values, not corrected for body surface area, with the associated percentile curves. For that purpose, the same patients as in the previous paper were selected, namely those with no recent urinary tract infection, having a normal left to right {sup 99m}Tc MAG3 uptake ratio and a normal kidney morphology on the early parenchymal images. A single blood sample method was used for {sup 51}Cr EDTA clearance measurement. Clearance values, not corrected for body surface area, increased progressively up to the adolescence. The percentile curves were determined and allow, for a single patient, to estimate accurately the level of non-corrected clearance and the evolution with time, whatever the age. (orig.)

  8. Uncovering surface area and micropores in almond shell biochars by rainwater wash

    Science.gov (United States)

    Biochars have been considered for adsorption of contaminants in soil and water, as well as conditioning and improving soil quality. One important property of the biochar is surface area in the pores of the biochar. Biochars were created from almond shells from two almond varieties with different ash...

  9. Surface water and groundwater interaction in selected areas of Indus basin

    International Nuclear Information System (INIS)

    Akram, W.; Ahmad, M.; Tariq, J.A.; Latif, Z.; Malik, M.R.

    2011-08-01

    Isotope hydrological investigations were carried out in Marala-Khanki Area of Punjab for elucidating various aspects of surface water and groundwater interaction. Groundwater samples were collected on seasonal basis (low and high river discharge periods) while surface water (Chenab River) samples were collected more frequently (weekly or monthly basis). Isotopic data suggested that there is no significant contribution of surface water to groundwater recharge in Marala-Khanki Area and rain is the prevailing source of groundwater recharge. The data further revealed that isotopic values of Tarbala lake are higher than those of main lake. Indus river meaning that there is significant contribution of base flow in this pocket. Isotopic data of Indus river showed an increase at Tunsa as compared to Chashma in flow period indicating the high contribution of base flow at this point in time. Stable isotopes were successfully used to quantify the base flow contribution. (author)

  10. A Three-Dimensional Enormous Surface Area Aluminum Microneedle Array with Nanoporous Structure

    Directory of Open Access Journals (Sweden)

    Po Chun Chen

    2013-01-01

    Full Text Available We proposed fabricating an aluminum microneedle array with a nanochannel structure on the surface by combining micromachining, electrolyte polishing, and anodization methods. The microneedle array provides a three-dimensional (3D structure that possesses several hundred times more surface area than a traditional nanochannel template. Therefore, the microneedle array can potentially be used in many technology applications. This 3D microneedle array device can not only be used for painless injection or extraction, but also for storage, highly sensitive detection, drug delivery, and microelectrodes. From the calculation we made, the microneedle array not only increases surface area, but also enlarges the capacity of the device. Therefore, the microneedle array can further be used on many detecting, storing, or drug delivering applications.

  11. A Three-Dimensional Enormous Surface Area Aluminum Microneedle Array with Nanoporous Structure

    International Nuclear Information System (INIS)

    Chen, P.Ch.; Zou, J.; Hsieh, Sh.J.; Chen, Ch.Ch.

    2013-01-01

    We proposed fabricating an aluminum micro needle array with a nano channel structure on the surface by combining micromachining, electrolyte polishing, and anodization methods. The micro needle array provides a three-dimensional (3D) structure that possesses several hundred times more surface area than a traditional nano channel template. Therefore, the micro needle array can potentially be used in many technology applications. This 3D micro needle array device can not only be used for painless injection or extraction, but also for storage, highly sensitive detection, drug delivery, and microelectrodes. From the calculation we made, the micro needle array not only increases surface area, but also enlarges the capacity of the device. Therefore, the micro needle array can further be used on many detecting, storing, or drug delivering applications.

  12. Seeded on-surface supramolecular growth for large area conductive donor-acceptor assembly.

    Science.gov (United States)

    Goudappagouda; Chithiravel, Sundaresan; Krishnamoorthy, Kothandam; Gosavi, Suresh W; Babu, Sukumaran Santhosh

    2015-07-04

    Charge transport features of organic semiconductor assemblies are of paramount importance. However, large-area extended supramolecular structures of donor-acceptor combinations with controlled self-assembly pathways are hardly accessible. In this context, as a representative example, seeded on-surface supramolecular growth of tetrathiafulvalene and tetracyano-p-quinodimethane (TTF-TCNQ) using active termini of solution-formed sheaves has been introduced to form an extended assembly. We demonstrate for the first time, the creation of a large-area donor-acceptor assembly on the surface, which is practically very tedious, using a seeded, evaporation-assisted growth process. The excellent molecular ordering in this assembly is substantiated by its good electrical conductivity (~10⁻² S cm⁻¹). The on-surface assembly via both internally formed and externally added sheaf-like seeds open new pathways in supramolecular chemistry and device applications.

  13. Investigation on large-area fabrication of vivid shark skin with superior surface functions

    Science.gov (United States)

    Chen, Huawei; Zhang, Xin; Ma, Lingxi; Che, Da; Zhang, Deyuan; Sudarshan, T. S.

    2014-10-01

    Shark skin has attracted worldwide attention because of its superior drag reduction, antifouling performance induced from its unique surface morphology. Although the vivid shark skin has been fabricated by a bio-replicated micro-imprinting approach in previous studies and superior drag reduction effect has been validated in water tunnel, continuous large-area fabrication is still an obstacle to wide apply. In this paper, one novel bio-replication coating technology is proposed for large-area transfer of shark skin based on rapid UV curable paint. Apart from design of coating system, bio-replication accuracy of surface morphology was validated about 97% by comparison between shark skin template and coating surface morphology. Finally, the drag reduction and anti-fouling function of coating surface were tested in water tunnel and open algae pond respectively. Drag reduction rate of coating surface was validated about 12% higher and anti-fouling was proved to about hundred times ameliorate, all of which are more excellent than simple 2D riblet surface.

  14. Adsorption of Ten Microcystin Congeners to Common Laboratory-Ware Is Solvent and Surface Dependent

    Directory of Open Access Journals (Sweden)

    Stefan Altaner

    2017-04-01

    Full Text Available Cyanobacteria can produce heptapetides called microcystins (MC which are harmful to humans due to their ability to inhibit cellular protein phosphatases. Quantitation of these toxins can be hampered by their adsorption to common laboratory-ware during sample processing and analysis. Because of their structural diversity (>100 congeners and different physico-chemical properties, they vary in their adsorption to surfaces. In this study, the adsorption of ten different MC congeners (encompassing non-arginated to doubly-arginated congeners to common laboratory-ware was assessed using different solvent combinations. Sample handling steps were mimicked with glass and polypropylene pipettes and vials with increasing methanol concentrations at two pH levels, before analysis by liquid chromatography-tandem mass spectrometry. We demonstrated that MC adsorb to polypropylene surfaces irrespective of pH. After eight successive pipet actions using polypropylene tips ca. 20% of the MC were lost to the surface material, which increased to 25%–40% when solutions were acidified. The observed loss was alleviated by changing the methanol (MeOH concentration in the final solvent. The required MeOH concentration varied depending on which congener was present. Microcystins only adsorbed to glass pipettes (loss up to 30% after eight pipet actions when in acidified aqueous solutions. The latter appeared largely dependent on the presence of ionizable groups, such as arginine residues.

  15. Size-dependent Young’s modulus in ZnO nanowires with strong surface atomic bonds

    Science.gov (United States)

    Fan, Shiwen; Bi, Sheng; Li, Qikun; Guo, Qinglei; Liu, Junshan; Ouyang, Zhongliang; Jiang, Chengming; Song, Jinhui

    2018-03-01

    The mechanical properties of size-dependent nanowires are important in nano-electro-mechanical systems (NEMSs), and have attracted much research interest. Characterization of the size effect of nanowires in atmosphere directly to broaden their practical application instead of just in high vacuum situations, as reported previously, is desperately needed. In this study, we systematically studied the Young’s modulus of vertical ZnO nanowires in atmosphere. The diameters ranged from 48 nm to 239 nm with a resonance method using non-contact atomic force microscopy. The values of Young’s modulus in atmosphere present extremely strong increasing tendency with decreasing diameter of nanowire due to stronger surface atomic bonds compared with that in vacuum. A core-shell model for nanowires is proposed to explore the Young’s modulus enhancement in atmosphere, which is correlated with atoms of oxygen occurring near the nanowire surface. The modified model is more accurate for analyzing the mechanical behavior of nanowires in atmosphere compared with the model in vacuum. Furthermore, it is possible to use this characterization method to measure the size-related elastic properties of similar wire-sharp nanomaterials in atmosphere and estimate the corresponding mechanical behavior. The study of the size-dependent Young’s modulus in ZnO nanowires in atmosphere will improve the understanding of the mechanical properties of nanomaterials as well as providing guidance for applications in NEMSs, nanogenerators, biosensors and other related areas.

  16. Research surface resistance of copper normal and abnormal skin-effects depending on the frequency of electromagnetic field

    International Nuclear Information System (INIS)

    Kutovyi, V.A.; Komir, A.I.

    2013-01-01

    The results of the frequency dependence of surface resistance of copper in diffuse and specular reflection of electrons from the conductive surface of the high-frequency resonance of the system depending on the frequency of the electromagnetic field in the normal and anomalous skin effect. Found, the surface resistance of copper is reduced by more than 10 times at the temperature of liquid helium, as compared with a surface resistivity at room temperature, at frequencies f ≤ 173 MHz, for diffuse reflection of conduction electrons from the surface of the conductive layer, and the specular reflection - at frequencies f ≤ 346 MHz

  17. Surface electric resistance of YBa2Cu3O7-δ ceramics and its dependence on magnetic field

    International Nuclear Information System (INIS)

    Gorochev, O.A.; Graboj, I.Eh.; Kaul', A.R.; Mitrofanov, V.P.

    1989-01-01

    Method of dielectric resonator in the 4.2-300 K temperature range is used to measure surface electric resistance of YBa 2 Cu 3 O 7-δ ceramics samples produced by different technologies. The temperature dependence of surface resistance near transition temperature is calculated. At 77.3 K dependence of electric resistance on external magnetic field at H≤200Oe is determined. Calculated dependence is verified in experiment

  18. Time-Dependent Cryospheric Longwave Surface Emissivity Feedback in the Community Earth System Model

    Science.gov (United States)

    Kuo, Chaincy; Feldman, Daniel R.; Huang, Xianglei; Flanner, Mark; Yang, Ping; Chen, Xiuhong

    2018-01-01

    Frozen and unfrozen surfaces exhibit different longwave surface emissivities with different spectral characteristics, and outgoing longwave radiation and cooling rates are reduced for unfrozen scenes relative to frozen ones. Here physically realistic modeling of spectrally resolved surface emissivity throughout the coupled model components of the Community Earth System Model (CESM) is advanced, and implications for model high-latitude biases and feedbacks are evaluated. It is shown that despite a surface emissivity feedback amplitude that is, at most, a few percent of the surface albedo feedback amplitude, the inclusion of realistic, harmonized longwave, spectrally resolved emissivity information in CESM1.2.2 reduces wintertime Arctic surface temperature biases from -7.2 ± 0.9 K to -1.1 ± 1.2 K, relative to observations. The bias reduction is most pronounced in the Arctic Ocean, a region for which Coupled Model Intercomparison Project version 5 (CMIP5) models exhibit the largest mean wintertime cold bias, suggesting that persistent polar temperature biases can be lessened by including this physically based process across model components. The ice emissivity feedback of CESM1.2.2 is evaluated under a warming scenario with a kernel-based approach, and it is found that emissivity radiative kernels exhibit water vapor and cloud cover dependence, thereby varying spatially and decreasing in magnitude over the course of the scenario from secular changes in atmospheric thermodynamics and cloud patterns. Accounting for the temporally varying radiative responses can yield diagnosed feedbacks that differ in sign from those obtained from conventional climatological feedback analysis methods.

  19. Surface functionalization dependent subcellular localization of Superparamagnetic nanoparticle in plasma membrane and endosome.

    Science.gov (United States)

    Thimiri Govinda Raj, Deepak B; Khan, Niamat Ali

    2018-01-01

    In this article, we elaborate the application of thermal decomposition based synthesis of Fe 3 O 4 superparamagnetic nanoparticle (SPMNP) in subcellular fractionation context. Here, we performed surface functionalization of SPMNP with phospholipids and dimercaptosuccinic acid. Surprisingly, we observed surface functionalization dependent SPMNP localization in subcellular compartments such as plasma membrane, endosomes and lysosomes. By using SPMNP based subcellular localization with pulse-chase methodology, we could use SPMNP for high pure-high yield organelle (plasma membrane, endosomes and lysosome) fractionation. Further, SPMNP that are distinctly localized in subcellular compartments can be used as technology for subcellular fractionation that can complement existing tools for cell biology research. As a future perspective, isolated magnetic organelles can be extended to protein/protein complex purification for biochemical and structural biology studies.

  20. Potential dependent adhesion forces on bare and underpotential deposition modified electrode surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Serafin, J.M.; Hsieh, S.J.; Monahan, J.; Gewirth, A.A. [Univ. of Illinois, Urbana, IL (United States)

    1998-12-03

    Adhesion force measurements are used to determine the potential dependence of the force of adhesion between a Si{sub 3}N{sub 4} cantilever and a Au(111) surface modified by the underpotential deposition (upd) of Bi or Cu in acid solution or by oxide formation. The measured work of adhesion is near zero for most of the potential region examined in Bi upd but rises after the formation of a full Bi monolayer. The work of adhesion is high at positive potentials for Cu upd but then decreases as the Cu partial and full monolayers are formed. The work of adhesion is low in the oxide region on Au(111) but rises following the sulfate disordering transition at 1.1 V vs NHE. These results are interpreted in terms of the degree of solvent order on the electrode surface.

  1. Regime-Dependent Differences in Surface Freshwater Exchange Estimates Over the Ocean

    Science.gov (United States)

    Wong, Sun; Behrangi, Ali

    2018-01-01

    Differences in gridded precipitation (P), surface evaporation (E), and the resultant surface freshwater exchange (P - E) among different products over the ocean are diagnosed as functions of moisture advection (Qadvt) and moisture tendency by dynamical convergence (Qcnvg). Compared to the GPCP product, the TRMM3B42 product captures higher frequency of precipitation with larger extreme precipitation rates in regimes of deep convection and more light rain detections in regimes of frequent occurrence of boundary layer clouds. Discrepancies in E depend on moisture flux divergence, with the OAFlux product having the largest E in regimes of divergence. Discrepancies in mean P - E in deep convective regimes are highly influenced by differences in precipitation, with the TRMM3B42 product yielding P - E histograms closer to those inferred from the reanalysis moisture flux convergence. In nonconvergent regimes, observation-based P - E histograms skew toward positive values while the inferred reanalysis histograms are symmetric about the means.

  2. Dependence of surface smoothing, sputtering and etching phenomena on cluster ion dosage

    CERN Document Server

    Song, J H; Choi, W K

    2002-01-01

    The dependence of surface smoothing and sputtering phenomena of Si (1 0 0) solid surfaces irradiated by CO sub 2 cluster ions on cluster-ion dosage was investigated using an atomic force microscope. The flux and total ion dosage of impinging cluster ions at the acceleration voltage of 50 kV were fixed at 10 sup 9 ions/cm sup 2 s and were scanned from 5x10 sup 1 sup 0 to 5x10 sup 1 sup 3 ions/cm sup 2 , respectively. The density of hillocks induced by cluster ion impact was gradually increased with the dosage up to 5x10 sup 1 sup 1 ions/cm sup 2 , which caused that the irradiated surface became rough from 0.4 to 1.24 nm in root-mean-square roughness (sigma sub r sub m sub s). At the boundary of the ion dosage of 10 sup 1 sup 2 ions/cm sup 2 , the density of the induced hillocks was decreased and sigma sub r sub m sub s was about 1.21 nm, not being deteriorated further. At the dosage of 5x10 sup 1 sup 3 ions/cm sup 2 , the induced hillocks completely disappeared and the surface became very flat as much as sigma...

  3. Surface-dependent chemical equilibrium constants and capacitances for bare and 3-cyanopropyldimethylchlorosilane coated silica nanochannels.

    Science.gov (United States)

    Andersen, Mathias Bækbo; Frey, Jared; Pennathur, Sumita; Bruus, Henrik

    2011-01-01

    We present a combined theoretical and experimental analysis of the solid-liquid interface of fused-silica nanofabricated channels with and without a hydrophilic 3-cyanopropyldimethylchlorosilane (cyanosilane) coating. We develop a model that relaxes the assumption that the surface parameters C(1), C(2), and pK(+) are constant and independent of surface composition. Our theoretical model consists of three parts: (i) a chemical equilibrium model of the bare or coated wall, (ii) a chemical equilibrium model of the buffered bulk electrolyte, and (iii) a self-consistent Gouy-Chapman-Stern triple-layer model of the electrochemical double layer coupling these two equilibrium models. To validate our model, we used both pH-sensitive dye-based capillary filling experiments as well as electro-osmotic current-monitoring measurements. Using our model we predict the dependence of ζ potential, surface charge density, and capillary filling length ratio on ionic strength for different surface compositions, which can be difficult to achieve otherwise. Copyright © 2010 Elsevier Inc. All rights reserved.

  4. Advancement in the Understanding of the Field and Frequency Dependent Microwave Surface Resistance of Niobium

    Energy Technology Data Exchange (ETDEWEB)

    Martinello, M. [Fermilab; Aderhold, S. [Fermilab; Chandrasekaran, S. K. [Fermilab; Checchin, M. [Fermilab; Grassellino, A. [Fermilab; Melnychuk, O. [Fermilab; Posen, S. [Fermilab; Romanenko, A. [Fermilab; Sergatskov, D. A. [Fermilab

    2017-07-24

    The radio-frequency surface resistance of niobium resonators is incredibly reduced when nitrogen impurities are dissolved as interstitial in the material, conferring ultra-high Q-factors at medium values of accelerating field. This effect has been observed in both high and low temperature nitrogen treatments. As a matter of fact, the peculiar anti Q-slope observed in nitrogen doped cavities, i.e. the decreasing of the Q-factor with the increasing of the radio-frequency field, come from the decreasing of the BCS surface resistance component as a function of the field. Such peculiar behavior has been considered consequence of the interstitial nitrogen present in the niobium lattice after the doping treatment. The study here presented show the field dependence of the BCS surface resistance of cavities with different resonant frequencies, such as: 650 MHz, 1.3 GHz, 2.6 GHz and 3.9 GHz, and processed with different state-of-the-art surface treatments. These findings show for the first time that the anti Q-slope might be seen at high frequency even for clean Niobium cavities, revealing useful suggestion on the physics underneath the anti Q-slope effect.

  5. A modified Poisson-Boltzmann surface excess calculation with a field dependent dielectric constant

    International Nuclear Information System (INIS)

    Gordillo, G.J.; Molina, F.V.; Posadas, D.

    1990-01-01

    The Unequal Radius Modified Gouy-Chapman (URMGC) was applied to mixtures of electrolytes. It was considered that the two anions, (1) and (2), have different radius, r 1 and r 2 , being r 2 smaller than r 1 . The dielectric constant was taken as a function of the electric field, using the theoretical Booth equation, or as a linear dependence varying between 6 and 78 when r 2 1 . The results show that the surface excess of anion 2 is much greater than the one predicted by Gouy-Chapman theory when the proportion of 2 increases in the mixture, while both the other anion and the cation show negative deviation. This effect is more evident in mixtures than in the case of single electrolytes, and has a maximum for a composition that depends on the chosen parameters for the model. (Author) [es

  6. Memory Effects and Coverage Dependence of Surface Diffusion in a Model Adsorption System

    DEFF Research Database (Denmark)

    Vattulainen, Ilpo Tapio; Ying, S. C.; Ala-Nissila, T.

    1999-01-01

    We study the coverage dependence of surface diffusion coefficients for a strongly interacting adsorption system O/W(110) via Monte Carlo simulations of a lattice-gas model. In particular, we consider the nature and emergence of memory effects as contained in the corresponding correlation factors...... diffusion is found to decay following a power law after an initial transient period. This behavior persists until the hydrodynamic regime is reached, after which the memory effect decays exponentially. The time required to reach the hydrodynamical regime and the related exponential decay is strongly...

  7. Perfluorinated compounds in soil, surface water, and groundwater from rural areas in eastern China.

    Science.gov (United States)

    Chen, Shu; Jiao, Xing-Chun; Gai, Nan; Li, Xiao-Jie; Wang, Xiao-Chun; Lu, Guo-Hui; Piao, Hai-Tao; Rao, Zhu; Yang, Yong-Liang

    2016-04-01

    Little research on perfluorinated compounds (PFCs) has been conducted in rural areas, although rural PFC sources are less complicated than in urban and industrial areas. To determine the levels and geographical distribution of 17 PFC compounds, samples of soil, surface water, and groundwater were collected from eight rural areas in eastern China. The total PFC concentrations (∑PFCs) in soils ranged from 0.34 to 65.8 ng/g ∑PFCs in surface waters ranged from 7.0 to 489 ng/L and ∑PFCs in groundwater ranged from 5.3 to 615 ng/L. Ratios of perfluorononanoic acid/perfluorooctanoic acid (PFNA/PFOA), perfluoro-n-butyric acid/perfluorooctanoic acid (PFBA/PFOA), and perfluoroheptanoic acid/perfluorooctanoic acid (PFHpA/PFOA) in rainwater increased due to the fluorine chemical plants in the surrounding rural and urban areas, suggesting that atmospheric precipitation may carry PFCs and their precursors from the fluorochemical industrial area to the adjacent rural areas. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Burning velocity and flame surface area in high Karlovitz number flames

    Science.gov (United States)

    Lapointe, Simon; Cheng, Lionel; Blanquart, Guillaume

    2017-11-01

    Accurate knowledge of the burning velocity of turbulent flames is of importance for many combustion devices. For low Karlovitz number flames, Damkohler proposed that the ratio of turbulent to laminar flame speed is proportional to the ratio of turbulent to laminar flame surface area. In recent DNS studies, it has been observed that Damkolher's scaling for low Karlovitz number flames still holds for high Karlovitz number flames. However, recent experimental studies have reported notable differences between global burning velocities and flame surface area measurements. In this work, the numerical and experimental results are further analyzed to explain the apparent contradiction. Emphasis is placed on identifying and quantifying potential experimental limitations at high Karlovitz numbers. More specifically, experimental flame surface measurements typically use binarized PLIF images. These images are two-dimensional and their resolution is limited by that of the PLIF system. The implications of using a two-dimensional iso-contour and the effects of the image resolution are assessed through post-processing of DNS datasets. Furthermore, the effects of integral length scale, Karlovitz number, and differential diffusion on the flame surface area are considered separately.

  9. Area Estimation of Deep-Sea Surfaces from Oblique Still Images.

    Directory of Open Access Journals (Sweden)

    Frederico Carvalho Dias

    Full Text Available Estimating the area of seabed surfaces from pictures or videos is an important problem in seafloor surveys. This task is complex to achieve with moving platforms such as submersibles, towed or remotely operated vehicles (ROV, where the recording camera is typically not static and provides an oblique view of the seafloor. A new method for obtaining seabed surface area estimates is presented here, using the classical set up of two laser devices fixed to the ROV frame projecting two parallel lines over the seabed. By combining lengths measured directly from the image containing the laser lines, the area of seabed surfaces is estimated, as well as the camera's distance to the seabed, pan and tilt angles. The only parameters required are the distance between the parallel laser lines and the camera's horizontal and vertical angles of view. The method was validated with a controlled in situ experiment using a deep-sea ROV, yielding an area estimate error of 1.5%. Further applications and generalizations of the method are discussed, with emphasis on deep-sea applications.

  10. Nanotechnological Advances in Catalytic Thin Films for Green Large-Area Surfaces

    Directory of Open Access Journals (Sweden)

    Suzan Biran Ay

    2015-01-01

    Full Text Available Large-area catalytic thin films offer great potential for green technology applications in order to save energy, combat pollution, and reduce global warming. These films, either embedded with nanoparticles, shaped with nanostructuring techniques, hybridized with other systems, or functionalized with bionanotechnological methods, can include many different surface properties including photocatalytic, antifouling, abrasion resistant and mechanically resistive, self-cleaning, antibacterial, hydrophobic, and oleophobic features. Thus, surface functionalization with such advanced structuring methods is of significance to increase the performance and wide usage of large-area thin film coatings specifically for environmental remediation. In this review, we focus on methods to increase the efficiency of catalytic reactions in thin film and hence improve the performance in relevant applications while eliminating high cost with the purpose of widespread usage. However, we also include the most recent hybrid architectures, which have potential to make a transformational change in surface applications as soon as high quality and large area production techniques are available. Hence, we present and discuss research studies regarding both organic and inorganic methods that are used to structure thin films that have potential for large-area and eco-friendly coatings.

  11. The reliability of three psoriasis assessment tools: Psoriasis area and severity index, body surface area and physician global assessment.

    Science.gov (United States)

    Bożek, Agnieszka; Reich, Adam

    2017-08-01

    A wide variety of psoriasis assessment tools have been proposed to evaluate the severity of psoriasis in clinical trials and daily practice. The most frequently used clinical instrument is the psoriasis area and severity index (PASI); however, none of the currently published severity scores used for psoriasis meets all the validation criteria required for an ideal score. The aim of this study was to compare and assess the reliability of 3 commonly used assessment instruments for psoriasis severity: the psoriasis area and severity index (PASI), body surface area (BSA) and physician global assessment (PGA). On the scoring day, 10 trained dermatologists evaluated 9 adult patients with plaque-type psoriasis using the PASI, BSA and PGA. All the subjects were assessed twice by each physician. Correlations between the assessments were analyzed using the Pearson correlation coefficient. Intra-class correlation coefficient (ICC) was calculated to analyze intra-rater reliability, and the coefficient of variation (CV) was used to assess inter-rater variability. Significant correlations were observed among the 3 scales in both assessments. In all 3 scales the ICCs were > 0.75, indicating high intra-rater reliability. The highest ICC was for the BSA (0.96) and the lowest one for the PGA (0.87). The CV for the PGA and PASI were 29.3 and 36.9, respectively, indicating moderate inter-rater variability. The CV for the BSA was 57.1, indicating high inter-rater variability. Comparing the PASI, PGA and BSA, it was shown that the PGA had the highest inter-rater reliability, whereas the BSA had the highest intra-rater reliability. The PASI showed intermediate values in terms of interand intra-rater reliability. None of the 3 assessment instruments showed a significant advantage over the other. A reliable assessment of psoriasis severity requires the use of several independent evaluations simultaneously.

  12. A Study of Impermeable Surfaces in the Greater Washington, D.C. Area

    OpenAIRE

    O'Connor, Mary; Chase-Walsh, Sarah; Cerquiera, Stephen

    2014-01-01

    The Washington D.C. area, like many cities, is covered with impermeable surfaces. With millions of cars on the roads every year, runoff is a major problem for the Potomac and the Anacostia rivers, which both empty into the Chesapeake Bay. Large buildings, constant construction, and an extensive highway system contribute to and expedite runoff. We will examine the amount of change in impermeable surfaces throughout the years and the effect runoff has on these two rivers. We also want to look a...

  13. The triazine-based porous organic polymer: Novel synthetic strategy for high specific surface area

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin Kuen [Dept. of Chemistry, Hankuk University of Foreign Studies, Yongin (Korea, Republic of)

    2017-02-15

    A new type of microporous polymer has been successively synthesized via a simple polycondensation reaction with the 2,4-diaminotriazine moiety and dianhydride monomer. Diaminotriazine moieties in M1 especially can provide effective branching sites, resulting in high surface areas up to 1150 m{sup 2} /g. In addition, the specific pore structure of the polyimide POP in its solid state can be modified by the surface activation method. Therefore, it can be expected that the resulting material will be a promising candidate for gas storage, and with this synthetic strategy, various type of derivatives will also be optimized.

  14. Influence of excess sodium ions on the specific surface area formation in a NiO-Al2O3 catalyst prepared by different methods

    Directory of Open Access Journals (Sweden)

    Lazić M.M.

    2008-01-01

    Full Text Available The influence of sodium ions on the specific surface area of a NiO-Al2O3 catalyst in dependence of nickel loading (5, 10, and 20 wt% Ni, temperature of heat treatment (400, 700 and 1100oC and the method of sample preparation was investigated. Low temperature nitrogen adsorption (LTNA, X-ray diffraction (XRD and scanning electron microscopy (SEM were applied for sample characterization. Dramatic differences in the specific surface area were registered between non-rinsed and rinsed Al2O3 and NiO-Al2O3 samples. The lagged sodium ions promote sintering of non-rinsed catalyst samples.

  15. Impervious Surfaces Alter Soil Bacterial Communities in Urban Areas: A Case Study in Beijing, China.

    Science.gov (United States)

    Hu, Yinhong; Dou, Xiaolin; Li, Juanyong; Li, Feng

    2018-01-01

    The rapid expansion of urbanization has caused land cover change, especially the increasing area of impervious surfaces. Such alterations have significant effects on the soil ecosystem by impeding the exchange of gasses, water, and materials between soil and the atmosphere. It is unclear whether impervious surfaces have any effects on soil bacterial diversity and community composition. In the present study, we conducted an investigation of bacterial communities across five typical land cover types, including impervious surfaces (concrete), permeable pavement (bricks with round holes), shrub coverage ( Buxus megistophylla Levl. ), lawns ( Festuca elata Keng ex E. Alexeev ), and roadside trees ( Sophora japonica Linn. ) in Beijing, to explore the response of bacteria to impervious surfaces. The soil bacterial communities were addressed by high-throughput sequencing of the bacterial 16S rRNA gene. We found that Proteobacteria , Actinobacteria , Acidobacteria , Bacteroidetes , Chloroflexi , and Firmicutes were the predominant phyla in urban soils. Soil from impervious surfaces presented a lower bacterial diversity, and differed greatly from other types of land cover. Soil bacterial diversity was predominantly affected by Zn, dissolved organic carbon (DOC), and soil moisture content (SMC). The composition of the bacterial community was similar under shrub coverage, roadside trees, and lawns, but different from beneath impervious surfaces and permeable pavement. Variance partitioning analysis showed that edaphic properties contributed to 12% of the bacterial community variation, heavy metal pollution explained 3.6% of the variation, and interaction between the two explained 33% of the variance. Together, our data indicate that impervious surfaces induced changes in bacterial community composition and decrease of bacterial diversity. Interactions between edaphic properties and heavy metals were here found to change the composition of the bacterial community and diversity

  16. Impervious Surfaces Alter Soil Bacterial Communities in Urban Areas: A Case Study in Beijing, China

    Directory of Open Access Journals (Sweden)

    Yinhong Hu

    2018-02-01

    Full Text Available The rapid expansion of urbanization has caused land cover change, especially the increasing area of impervious surfaces. Such alterations have significant effects on the soil ecosystem by impeding the exchange of gasses, water, and materials between soil and the atmosphere. It is unclear whether impervious surfaces have any effects on soil bacterial diversity and community composition. In the present study, we conducted an investigation of bacterial communities across five typical land cover types, including impervious surfaces (concrete, permeable pavement (bricks with round holes, shrub coverage (Buxus megistophylla Levl., lawns (Festuca elata Keng ex E. Alexeev, and roadside trees (Sophora japonica Linn. in Beijing, to explore the response of bacteria to impervious surfaces. The soil bacterial communities were addressed by high-throughput sequencing of the bacterial 16S rRNA gene. We found that Proteobacteria, Actinobacteria, Acidobacteria, Bacteroidetes, Chloroflexi, and Firmicutes were the predominant phyla in urban soils. Soil from impervious surfaces presented a lower bacterial diversity, and differed greatly from other types of land cover. Soil bacterial diversity was predominantly affected by Zn, dissolved organic carbon (DOC, and soil moisture content (SMC. The composition of the bacterial community was similar under shrub coverage, roadside trees, and lawns, but different from beneath impervious surfaces and permeable pavement. Variance partitioning analysis showed that edaphic properties contributed to 12% of the bacterial community variation, heavy metal pollution explained 3.6% of the variation, and interaction between the two explained 33% of the variance. Together, our data indicate that impervious surfaces induced changes in bacterial community composition and decrease of bacterial diversity. Interactions between edaphic properties and heavy metals were here found to change the composition of the bacterial community and

  17. Can We Trust Real Time Measurements of Lung Deposited Surface Area Concentrations in Dust from Powder Nanomaterials?

    DEFF Research Database (Denmark)

    Levin, Marcus; Witschger, Olivier; Bau, Sebastien

    2016-01-01

    A comparison between various methods for real-time measurements of lung deposited surface area (LDSA) using spherical particles and powder dust with specific surface area ranging from 0.03 to 112 m2 g-1 was conducted. LDSA concentrations measured directly using Nanoparticle Surface Area Monitor...... (NSAM) and Aerotrak and were compared to LDSA concentrations recalculated from size distribution measurements using Electrical Low Pressure Impactor (ELPI) and Fast Mobility Particle Sizer (FMPS). FMPS and ELPI measurements were also compared to dust surface area concentrations estimated from...... gravimetrical filter measurements and specific surface areas. Measurement of LDSA showed very good correlation in measurements of spherical particles (R2 > 0.97, Ratio 1.0 to 1.04). High surface area nanomaterial powders showed a fairly reliable correlation between NSAM and Aerotrak (R2 0...

  18. Use of surface area computations to describe atom-atom interactions.

    Science.gov (United States)

    de La Cruz, X; Calvo, M

    2001-06-01

    Accessible surface (ASA) and atomic contact (ACA) areas are powerful tools for protein structure analysis. However, their use for analysis purposes could be extended if a relationship between them and protein stability could be found. At present, this is the case only for ASAs, which have been used to assess the contribution of the hydrophobic effect to protein stability. In the present work we study whether there is a relationship between atomic contact areas and the free energy associated to atom-atom interactions. We utilise a model in which the contribution of atomic interactions to protein stability is expressed as a linear function of the accessible surface area buried between atom pairs. We assess the validity of this hypothesis, using a set of 124 lysozyme mutants (Matthews, 1995, Adv Protein Chem, 249-278) for which both the X-ray structure and the experimental stability are known. We tested this assumption for residue representations with increasing numbers of atom types. Our results indicate that for simple residue representations, with only 4 to 5 atom types, there is not a clear linear relationship between stability and buried accessible area. However, this relationship is observed for representations with 6 to 9 atom types, where gross heterogeneities in the atom type definition are eliminated. Finally, we also study a version of the linear model in which the atom- atom interactions are represented utilising a simple function for the buried accessible area, which may be useful for protein structure prediction studies.

  19. [Distribution Characteristics of Fluoroquinolones Antibiotics in Surface Water and Groundwater from Typical Areas in A City].

    Science.gov (United States)

    Cui, Ya-feng; He, Jiang-tao; Su, Si-hui; Yang, Lei; Qiao, Xiao-cui

    2015-11-01

    In order to investigate the characteristics of 5 typical kinds of fluoroquinolones (FQs) pollution in waters from a city, surface water and groundwater samples from main drainage rivers and typical areas were collected, respectively. The conventional test and FQs concentrations analysis of the water samples were conducted. The results showed the concentration and composition of FQs in groundwater differed substantially from those in surface water. The average concentration of FQs in surface water was 789.1 ng x L(-1) with the main components of ofloxacin (OFL) and lomefloxacin (LOM). This value was higher than the average concentration of FQs in groundwater: 342.7 ng x L(-1) with the main components of norfloxacin (NOR) and lomefloxacin (LOM). The enrofloxacin (ENR) exhibited relatively lower levels in both surface water and groundwater as compared to others. The highest FQs concentrations in surface water were found in trenches, followed by tributaries and the main stream. For groundwater, FQs concentrations were relatively higher in the sewage riverside. A decreasing trend of FQs concentration was monitored with the increasing distance of sampling points to the drainage rivers and all components mentioned above showed similar changing trends. The results of this study preliminarily indicated that FQs in groundwater along the riverside probably came from the surface water.

  20. Effect of preparation surface area on the clinical outcome of full veneer crowns in dogs.

    Science.gov (United States)

    Riehl, Jessica; Soukup, Jason W; Collins, Caitlyn; Siverling, Sarah; Ploeg, Heidi-Lynn; Snyder, Christopher J

    2014-01-01

    Crown therapy is commonly used in veterinary medicine to provide support to teeth which have previously fractured, received root canal therapy, have significant wear, or experienced other detrimental removal of tooth substance. As with several aspects of veterinary medicine, many of the recommendations or guidelines for crown therapy originate from human dentistry, which are then transferred to veterinary patients. Due to the significant difference in the anatomy of teeth and function of the oral cavity between humans and dogs, these guidelines need to be studied to determine the appropriateness of their use in veterinary patients. This article evaluates the relationship between surface area of the preparation and clinical outcome of full veneer crown therapy of the canine tooth in dogs. Although there appeared to be a positive relationship between preparations with greater surface area and successful clinical outcome, it was not found to be statistically significant.

  1. Phenomenological study of aerosol dry deposition in urban area: surface properties, turbulence and local meteorology influences

    International Nuclear Information System (INIS)

    Roupsard, P.

    2013-01-01

    Aerosol dry deposition is not much known for urban areas due to the lack of data. Knowledge on this phenomenon is necessary to understand pollutant fluxes in cities and to estimate inhabitant exposition to ionizing radiation of radioactive aerosols. A data providing could enable to enhance dry deposition models for these areas. An original experimental approach is performed to study submicron aerosol dry deposition on urban surfaces. Wind tunnel coupled to in situ experiments give results to study different physical phenomenon governing dry deposition. Dry deposition velocities are measured using aerosol tracers. These data are associated to turbulent and meteorological measured conditions. This database permits to classify the principal physical phenomenon for each experiment type. Finally, different phenomenon must be considered for chronic and acute exposition of urban surfaces to atmospheric particles. (author)

  2. Effect of perfusate hematocrit on urea permeability-surface area in isolated dog lung

    International Nuclear Information System (INIS)

    Parker, R.E.; Roselli, R.J.; Haselton, F.R.; Harris, T.R.

    1986-01-01

    Seven dog lower left lung lobes were statically inflated and perfused at a constant rate for each lobe with a perfusate in which the hematocrit was altered over a wide range. The permeability-surface area of urea was calculated from multiple indicator dilution curves using two separate injectates for each hematocrit level. One injectate contained only 125 I-albumin as the vascular reference tracer and the other contained both 51 Cr-erythrocytes and 125 I-albumin as the vascular reference tracers; both contained [ 14 C]urea as the permeating tracer. The results strongly indicate that the phenomenon of erythrocyte trapping of urea does not affect the calculation of urea permeability-surface area product provided the appropriate albumin-erythrocyte composite reference tracer is utilized in its calculation

  3. Temperature dependent surface modification of molybdenum due to low energy He+ ion irradiation

    International Nuclear Information System (INIS)

    Tripathi, J.K.; Novakowski, T.J.; Joseph, G.; Linke, J.; Hassanein, A.

    2015-01-01

    In this paper, we report on the temperature dependent surface modifications in molybdenum (Mo) samples due to 100 eV He + ion irradiation in extreme conditions as a potential candidate to plasma-facing components in fusion devices alternative to tungsten. The Mo samples were irradiated at normal incidence, using an ion fluence of 2.6 × 10 24 ions m −2 (with a flux of 7.2 × 10 20 ions m −2 s −1 ). Surface modifications have been studied using high-resolution field emission scanning electron-(SEM) and atomic force (AFM) microscopy. At 773 K target temperature homogeneous evolution of molybdenum nanograins on the entire Mo surface were observed. However, at 823 K target temperature appearance of nano-pores and pin-holes nearby the grain boundaries, and Mo fuzz in patches were observed. The fuzz density increases significantly with target temperatures and continued until 973 K. However, at target temperatures beyond 973 K, counterintuitively, a sequential reduction in the fuzz density has been seen till 1073 K temperatures. At 1173 K and above temperatures, only molybdenum nano structures were observed. Our temperature dependent studies confirm a clear temperature widow, 823–1073 K, for Mo fuzz formation. Ex-situ high resolution X-ray photoelectron spectroscopy studies on Mo fuzzy samples show the evidence of MoO 3 3d doublets. This elucidates that almost all the Mo fuzz were oxidized during open air exposure and are thick enough as well. Likewise the microscopy studies, the optical reflectivity measurements also show a sequential reduction in the reflectivity values (i.e., enhancement in the fuzz density) up to 973 K and after then a sequential enhancement in the reflectivity values (i.e., reduction in the fuzz density) with target temperatures. This is in well agreement with microscopy studies where we observed clear temperature window for Mo fuzz growth

  4. Rapid evaluation of machine tools with position-dependent milling stability based on response surface model

    Directory of Open Access Journals (Sweden)

    Li Zhang

    2016-03-01

    Full Text Available The milling stability is one of the important evaluation criterions of dynamic characteristics of machine tools, and it is of great importance for machine tools’ design and manufacturing. The milling stability of machine tools generally varies with the position combinations of moving parts. The traditional milling stability analysis of machine tools is based on some specific positions in the whole workspace of machine tools, and the results are not comprehensive. Furthermore, it is very time-consuming for operation and calculation to complete analysis of multiple positions. A new method to rapidly evaluate the stability of machine tools with position dependence is developed in this article. In this method, the key position combinations of moving parts are set as the samples of calculation to calculate the dynamic characteristics of machine tools with SAMCEF finite element simulation analysis software. Then the minimum critical axial cutting depth of each sample is obtained. The relationship between the position and the value of minimum critical axial cutting depth at any position in the whole workspace can be obtained through established response surface model. The precision of the response surface model is evaluated and the model could be used to rapidly evaluate the milling stability of machine tools with position dependence. With a precision horizontal machining center with box-in-box structure as an example, the value of minimum critical axial cutting depth at any position is shown. This method of rapid evaluation of machine tools with position-dependent stability avoids complicated theoretical calculation, so it can be easily adopted by engineers and technicians in the phase of design process of machine tools.

  5. Pretreatment-dependent surface chemistry of wood nanocellulose for pH-sensitive hydrogels.

    Science.gov (United States)

    Chinga-Carrasco, Gary; Syverud, Kristin

    2014-09-01

    Nanocellulose from wood is a promising material with potential in various technological areas. Within biomedical applications, nanocellulose has been proposed as a suitable nano-material for wound dressings. This is based on the capability of the material to self-assemble into 3D micro-porous structures, which among others have an excellent capacity of maintaining a moist environment. In addition, the surface chemistry of nanocellulose is suitable for various applications. First, OH-groups are abundant in nanocellulose materials, making the material strongly hydrophilic. Second, the surface chemistry can be modified, introducing aldehyde and carboxyl groups, which have major potential for surface functionalization. In this study, we demonstrate the production of nanocellulose with tailor-made surface chemistry, by pre-treating the raw cellulose fibres with carboxymethylation and periodate oxidation. The pre-treatments yielded a highly nanofibrillated material, with significant amounts of aldehyde and carboxyl groups. Importantly, the poly-anionic surface of the oxidized nanocellulose opens up for novel applications, i.e. micro-porous materials with pH-responsive characteristics. This is due to the swelling capacity of the 3D micro-porous structures, which have ionisable functional groups. In this study, we demonstrated that nanocellulose gels have a significantly higher swelling degree in neutral and alkaline conditions, compared to an acid environment (pH 3). Such a capability can potentially be applied in chronic wounds for controlled and intelligent release of antibacterial components into biofilms. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  6. Estimation of small reservoir storage capacities in the São Francisco, Limpopo, Bandama and Volta river basins using remotely sensed surface areas

    Science.gov (United States)

    Rodrigues, Lineu; Senzanje, Aidan; Cecchi, Philippe; Liebe, Jens

    2010-05-01

    area, depth and shape. Depth was measured using a stadia rod or a manual echosounder. For reservoirs in the sub-set, estimated surface area was used as an input into the triangulated irregular network model. With the surface area and depth, measured volume was calculated. Comparisons were made between estimates of surface area from field surveys and estimates of surface area from remote sensing. A linear regression analysis was carried out to establish the relationship between surface area and storage capacities. Within geomorphologically homogenous regions, one may expect a good correlation between the surface area, which may be determined through satellite observations, and the stored volume. Such a relation depends on the general shape of the slopes (convex, through straight, to concave). The power relationships between remotely sensed surface areas (m^2) and storage capacities of reservoirs (m^3) obtained were - Limpopo basin (Lower Mzingwane sub-catchment): Volume = 0.023083 x Area^1.3272 (R2 = 95%); Bandama basin (North of the basin in Ivory Coast): Volume = 0.00405 x Area^1.4953 (R2 = 88.9%); Volta basin (Upper East region of the Volta Basin in Ghana): Volume = 0.00857 × Area^1.43 (R2 = 97.5%); São Francisco basin (Preto river sub-catchment): Volume = 0.2643 x Area^1.1632 (R2 = 92.1%). Remote sensing was found to be a suitable means to detect small reservoirs and accurately measure their surface areas. The general relationship between measured reservoir volumes and their remotely sensed surface areas showed good accuracy for all four basins. Combining such relationships with periodical satellite-based reservoir area measurements may allow hydrologists and planners to have clear picture of water resource system in the Basins, especially in ungauged sub-basins.

  7. Surface area of lactose and lactose granulates on consolidation and compaction

    OpenAIRE

    Riepma, Klaas Alouis

    1993-01-01

    This dissertation discusses the effect of short time storage at different conditions on the strength and the specific BET surface area of lactose tablets. In addition, some aspects are studied of the consolidation and compaction properties of crystalline lactose fractions in heterogeneous systems. The crystalline lactose types used are: a-lactose monohydrate, anhydrous a-lactose, crystalline B-lactose and roller dried B-lactose. ... Zie: Summary

  8. Synthesis of high-surface-area spinel-type MgAl2O4 nanoparticles ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 40; Issue 1. Synthesis of high-surface-area spinel-type MgAl 2 O 4 nanoparticles by [Al(sal) 2 (H 2 O) 2 ] 2 [Mg(dipic) 2 ] and [Mg(H 2 O) 6 ][Al(ox) 2 (H 2 O) 2 ] 2 ·5H 2 O: influence of inorganic precursor type. Volume 40 Issue 1 February 2017 pp 45-53 ...

  9. Sensitivity analysis of the surface water- groundwater interaction for the sandy area of the Netherlands

    OpenAIRE

    Gomez del Campo, E.; Jousma, G.; Massop, H.T.L.

    1993-01-01

    The "Sensitivity Analysis of the Surface Water- Groundwater Interaction for the Sandy Area of the Netherlands" was carried out in the framework of a bilateral research project in support of the implementation of a nationwide geohydrological information system (REGIS) in the Netherlands. This project, conducted in cooperation between the TNO Institute for Applied Scientific Research (IGG-TNO) and !he Winand Staring Centre for Integrated Land, Soil and Water Research (SC-DLO), is aimed at defin...

  10. Formula and Scale for Body Surface Area Estimation in High-Risk Infants

    OpenAIRE

    Ahn, Youngmee

    2010-01-01

    Advances in medical technology and the health sciences have lead to a rapid increase in the prevalence and morbidity of high-risk infants with chronic or permanent sequels such as the birth of early preterm infants. A suitable formula is therefore needed for body surface area (BSA) estimation for high-risk infants to more accurately devise therapeutic regimes in clinical practice. A cohort study involving 5014 high-risk infants was conducted to develop a suitable formula for estimating BSA us...

  11. High-Surface-Area Porous Platinum Electrodes for Enhanced Charge Transfer

    OpenAIRE

    Hu Yelin; Yella Aswani; Guldin Stefan; Schreier Marcel; Stellacci Francesco; Grätzel Michael; Stefik Morgan

    2014-01-01

    Cobalt based electrolytes are highly tunable and have pushed the limits of dye sensitized solar cells enabling higher open circuit voltages and new record effi ciencies. However the performance of these electrolytes and a range of other electrolytes suffer from slow electron transfer at platinum counter electrodes. High surface area platinum would enhance catalysis but pure platinum structures are too expensive in practice. Here a material effi cient host guest architecture is developed that ...

  12. n-Alkylamine-assisted preparation of a high surface area vanadyl phosphate/tetraethylorthosilicate nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, João Paulo L., E-mail: billbrujah@yahoo.com.br [Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes 3900, Ribeirão Preto, SP 14040-901 (Brazil); Zampronio, Elaine C.; Oliveira, Herenilton P. [Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes 3900, Ribeirão Preto, SP 14040-901 (Brazil)

    2013-02-15

    Graphical abstract: CuK{sub α} X-ray diffraction patterns of the VP, VPOc, VPOcT, VPOcT200 and VPOcT500. Highlights: ► TEOS and octylamine incorporation into the VP was achieved by expanding the lamellar. ► The specific surface area increased from 15 m{sup 2} g{sup −1} in VP to 237 m{sup 2} g{sup −1} in VPOcT. ► The VPOcT exhibited thermal resistance up to 200 °C in air. ► Upon thermal treatment up to 500 °C, the surface area increased to 838 m{sup 2} g{sup −1}. -- Abstract: We have developed a vanadyl phosphate/tetraethylorthosilicate (VPO/TEOS) nanocomposite comprised of silicate chains interleaved with VPO layers, prepared by using an n-alkylamines such as octylamine as the structure directing agent. The nanocomposites were synthesized by reacting amine-intercalated vanadyl phosphate with tetraethylorthosilicate via the soft chemistry approach. The synthetic procedure encompassed the exfoliation of the layered vanadyl phosphate as well as the reorganization of this exfoliated solid into a mesostructured lamellar phase with the same V–P–O connectivity as in the original matrix. TEOS incorporation into the vanadyl phosphate was achieved by expanding the lamellar structure with n-alkylamine (Δd = 13 Å with n-octylamine). The specific surface area increased from 15 m{sup 2} g{sup −1} in the vanadyl phosphate matrix to 237 m{sup 2} g{sup −1} in VPOcT, and the isotherm curves revealed the characteristic hysteresis of mesoporous materials. Upon thermal treatment up to 500 °C, the surface area increased to 837 m{sup 2} g{sup −1}, which is suitable for catalytic purposes.

  13. Growth of Hierarchically Structured High-Surface Area Alumina on FeCrAl Alloy Wires

    Directory of Open Access Journals (Sweden)

    Chandni Rallan

    2013-01-01

    Full Text Available The formation of metastable alumina phases due to the oxidation of commercial FeCrAl alloy wires (0.5 mm thickness at various temperatures and time periods has been examined. Samples were isothermally oxidised in air using a thermogravimetric analyzer (TGA. The morphology of the oxidised samples was analyzed using an Electronic Scanning Electron Microscope (ESEM and X-ray on the surface analysis was done using an Energy Dispersive X-Ray (EDX analyzer. The technique of X-Ray Diffraction (XRD was used to characterize the phase of the oxide growth. The entire study showed that it was possible to grow high-surface area gamma alumina on the FeCrAl alloy wire surfaces when isothermally oxidised above 800°C over several hours.

  14. How Much Global Burned Area Can Be Forecast on Seasonal Time Scales Using Sea Surface Temperatures?

    Science.gov (United States)

    Chen, Yang; Morton, Douglas C.; Andela, Niels; Giglio, Louis; Randerson, James T.

    2016-01-01

    Large-scale sea surface temperature (SST) patterns influence the interannual variability of burned area in many regions by means of climate controls on fuel continuity, amount, and moisture content. Some of the variability in burned area is predictable on seasonal timescales because fuel characteristics respond to the cumulative effects of climate prior to the onset of the fire season. Here we systematically evaluated the degree to which annual burned area from the Global Fire Emissions Database version 4 with small fires (GFED4s) can be predicted using SSTs from 14 different ocean regions. We found that about 48 of global burned area can be forecast with a correlation coefficient that is significant at a p burning. Continental regions where burned area had a higher degree of predictability included equatorial Asia, where 92% of the burned area exceeded the correlation threshold, and Central America, where 86% of the burned area exceeded this threshold. Pacific Ocean indices describing the El Nino-Southern Oscillation were more important than indices from other ocean basins, accounting for about 1/3 of the total predictable global burned area. A model that combined two indices from different oceans considerably improved model performance, suggesting that fires in many regions respond to forcing from more than one ocean basin. Using OCI-burned area relationships and a clustering algorithm, we identified 12 hotspot regions in which fires had a consistent response to SST patterns. Annual burned area in these regions can be predicted with moderate confidence levels, suggesting operational forecasts may be possible with the aim of improving ecosystem management.

  15. [Distribution, surface and protected area of palm-swamps in Costa Rica and Nicaragua].

    Science.gov (United States)

    Serrano-Sandí, Juan; Bonilla-Murillo, Fabian; Sasa, Mahmood

    2013-09-01

    In Central America, palm swamps are known collectively as yolillales. These wetlands are usually dominated by the raffia palm Raphia taedigera, but also by the royal palm Manicaria saccifera and -in lower extensions- by the American oil palm Elaeis oleifera. The yolillales tend to be poor in woody species and are characteristic of regions with high rainfall and extensive hydroperiods, so they remain flooded most of the year. The dominance of large raffia palm leaves in the canopy, allow these environments to be distinguishable in aerial photographs, which consequently has helped to map them along most of their distribution. However, while maps depicting yolillales are available, the extent of their surface area, perimeter and connectivity remains poorly understood. This is particularly true for yolillales in Costa Rica and Nicaragua, countries that share a good proportion of palm dominated swaps in the Rio San Juan Basin. In addition, it is not known the actual area of these environments that is under any category of protection according to the conservation systems of both countries. As a first step to catalog yolillal wetlands in Costa Rica and Nicaragua, this paper evaluates cartographic maps to delineate yolillales in the region. A subsample of yolillales mapped in this study were visited and we geo-referenced them and evaluate the extent and condition of the swamp. A total of 110 883.2ha are classified as yolillales in Nicaragua, equivalent to 22% of wetland surface area recorded for that country (excluding the Cocibolca and Xolothn Lakes). In Costa Rica, 53 931.3ha are covered by these palm dominated swamps, which represent 16.24% of the total surface area covered by wetlands. About 47% of the area covered by yolillales in Nicaragua is under some category of protection, the largest extensions protected by Cerro Silva, Laguna Tale Sulumas and Indio Maiz Nature Reserves. In Costa Rica, 55.5% of the area covered by yolillal is located within protected areas

  16. Geographical altitude, size, mass and body surface area in children (1-4 years) in the Province of Jujuy (Argentina).

    Science.gov (United States)

    Román, Estela María; Bejarano, Ignacio Felipe; Alfaro, Emma Laura; Abdo, Guadalupe; Dipierri, José Edgardo

    2015-01-01

    Highland child populations show low growth rates. To evaluate the variation of size, mass and body surface area of Jujenean infants (1-4 years) as a function of geographic altitude. Nutritional status of 8059 healthy infants was determined based on weight and height data; body mass index, ponderal index, body surface area, body surface area/mass and ectomorphy were calculated. Variables were standardized with a provincial mean and WHO references. Data were grouped by age, sex and geographic altitude: Highlands (≥2500 masl) and Lowlands (children differ in size, mass and body surface area based on the geographical altitude and adverse nutritional and socioeconomic factors.

  17. Effect of Precipitation Conditions on the Specific Surface Area of Neptunium Oxide

    International Nuclear Information System (INIS)

    HILL, BENJAMINC.

    2004-01-01

    Neptunium oxalate was precipitated under nominal and bounding HB-Line flowsheet conditions. The nominal case represents expected normal HB-Line operation. The bounding case represents process flowsheet extremes that could occur which are anticipated to decrease particle size and increase surface area. The neptunium oxalate produced under bounding conditions was used to validate the effectiveness of HB-Line calcination conditions. The maximum specific surface area of the neptunium oxide (NpO2) used in gas generation testing was 5.34 m2/g. Experiments were conducted to verify that even under bounding precipitation conditions the SSA of NpO2 produced would remain within the range evaluated during gas generation testing. The neptunium oxalate from nominal and bounding precipitation conditions was calcined at 600 degrees Celsius and 625 degrees Celsius, respectively, to form NpO2. Samples from each batch of neptunium oxalate were calcined for one, two, or four hours. Results indicate that the SSA of NpO2 continues to decrease between one and four hours. After two hours of calcination at 625 degrees Celsius, the SSA of NpO2 from the bounding case meets the surface area requirements for limiting moisture uptake

  18. Preparation of high surface area and high conductivity polyaniline nanoparticles using chemical oxidation polymerization technique

    Science.gov (United States)

    Budi, S.; Yusmaniar; Juliana, A.; Cahyana, U.; Purwanto, A.; Imaduddin, A.; Handoko, E.

    2018-03-01

    In this work, polyaniline nanoparticles were synthesized using a chemical oxidation polymerization technique. The ammonium peroxydisulfate (APS)/aniline ratio, APS dropping time, and polymerization temperature were optimized to increase the surface area and conductivity of the polyaniline.The Fourier-transform infrared (FTIR) spectrum confirmed the formation of emeraldine salt polyaniline. X-ray diffraction (XRD) patterns indicated that amorphous and crystalline phases of the polyaniline were formed with crystallinity less than 40%. Scanning electron microscope (SEM) micrographs showed that the finest nanoparticles with uniform size distribution were obtained at the polymerization temperature of 0°C. A surface area analyzer (SAA) showed that the highest Brunauer-Emmett-Teller surface area (SBET ) of 42.14 m2/gwas obtained from an APS/aniline ratio of 0.75 with a dropping time of 0 s at a polymerization temperature of 0°C. A four-point probe measurement conducted at 75–300K indicated relatively high conductivity of the semiconductor characteristic of the polyaniline.

  19. Effects of acid treatment on the clay palygorskite: XRD, surface area, morphological and chemical composition

    Energy Technology Data Exchange (ETDEWEB)

    Xavier, Katiane Cruz Magalhaes; Santos, Maria do Socorro Ferreira dos; Santos, Maria Rita Morais Chaves; Oliveira, Marilia Evelyn Rodrigues; Osajima, Josy Antevelli; Silva Filho, Edson Cavalcanti da [Universidade Federal do Piaui (UFPI), Teresina, PI (Brazil); Carvalho, Maria Wilma Nunes Cordeiro, E-mail: edsonfilho@ufpi.edu.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

    2014-08-15

    The palygorskite is an aluminum-magnesium silicate that has a fibrous morphology. Their physicochemical characteristics are the result of high surface area, porosity and thermal resistance which make it an attractive adsorbent. Its adsorption capacity can be increased through chemical reactions and/or heat treatments. The objective of this work is to verify the effects of acid activation on the palygorskite, treated with HCl at 90 °C at concentrations of 2, 4 and 6 mol L{sup -1} in 2 and 4 hours, with clay/acid solution ratio 1 g 10 mL{sup -1} and characterized by techniques: XRF, XRD and surface area. A significant increase in specific surface area was observed in the sample treated with HCl at the concentration 6 mol L{sup -1}. The changes were more pronounced at stricter concentrations of acidity, with decreasing intensity of reflection of the clay indicated in the XRD. These changes were confirmed in the XRF with the leaching of some oxides and with increasing concentration of SiO{sub 2}. (author)

  20. Relationship Between the Surface Area to Volume Ratio and Temperature across Geologic Time in Ostracods

    Science.gov (United States)

    Jackson, C.; Zaroff, S.; Heim, N. A.; Payne, J.

    2014-12-01

    In 1877 Joseph Allen proposed that endothermic terrestrial organisms would have lower surface area to volume ratios (SAVR) in colder climates and higher SAVRs in warmer climates. With a smaller surface area compared to volume, organisms can retain more heat in cold climates. We tested to see if this principle applied to ostracods, a type of ectothermic marine invertebrate. We hypothesised that Allen's rule applies to ostracods, as Allen's rule has been demonstrated in frogs (Alho 2011), which are also ectotherms . We used the linear dimensions of the three major carapace axes of ostracod holotypes to estimate the SAVR. We compared ostracod SAVRs with paleotemperatures from Royer et al. (2004). We found that there was a correlation between surface area and temperature; it is a small, but statistically significant correlation (adj. R2=0.0167). This means that as temperature increased, the SAVR also increased. We also found a negative correlation between ostracod SAVR to geologic time(adj. R2=0.0114), which shows us that as time has gone on, ostracod SAVR has decreased. We then plotted the correlation coefficient of SAVR to temperature over geologic time to explore trends in the strength of Allen's rule. For most of time there was no relationship but during the Devonian, Allen's Rule did explain the trend. In short, temperature does explain some of the correlation between the SAVR and temperature, but it is likely there were other environmental factors affecting this relationship.

  1. Mineral paragenesis on Mars: The roles of reactive surface area and diffusion.

    Science.gov (United States)

    Fairén, Alberto G; Gil-Lozano, Carolina; Uceda, Esther R; Losa-Adams, Elisabeth; Davila, Alfonso F; Gago-Duport, Luis

    2017-09-01

    Geochemical models of secondary mineral precipitation on Mars generally assume semiopen systems (open to the atmosphere but closed at the water-sediment interface) and equilibrium conditions. However, in natural multicomponent systems, the reactive surface area of primary minerals controls the dissolution rate and affects the precipitation sequences of secondary phases, and simultaneously, the transport of dissolved species may occur through the atmosphere-water and water-sediment interfaces. Here we present a suite of geochemical models designed to analyze the formation of secondary minerals in basaltic sediments on Mars, evaluating the role of (i) reactive surface areas and (ii) the transport of ions through a basalt sediment column. We consider fully open conditions, both to the atmosphere and to the sediment, and a kinetic approach for mineral dissolution and precipitation. Our models consider a geochemical scenario constituted by a basin (i.e., a shallow lake) where supersaturation is generated by evaporation/cooling and the starting point is a solution in equilibrium with basaltic sediments. Our results show that cation removal by diffusion, along with the input of atmospheric volatiles and the influence of the reactive surface area of primary minerals, plays a central role in the evolution of the secondary mineral sequences formed. We conclude that precipitation of evaporites finds more restrictions in basaltic sediments of small grain size than in basaltic sediments of greater grain size.

  2. Surface water areas significantly impacted 2014 dengue outbreaks in Guangzhou, China

    International Nuclear Information System (INIS)

    Tian, Huaiyu; Huang, Shanqian; Zhou, Sen; Bi, Peng; Yang, Zhicong; Li, Xiujun; Chen, Lifan; Cazelles, Bernard; Yang, Jing; Luo, Lei; Jing, Qinlong; Yuan, Wenping; Pei, Yao; Sun, Zhe; Yue, Tianxiang; Kwan, Mei-Po

    2016-01-01

    Dengue transmission in urban areas is strongly influenced by a range of biological and environmental factors, yet the key drivers still need further exploration. To better understand mechanisms of environment–mosquito–urban dengue transmission, we propose an empirical model parameterized and cross-validated from a unique dataset including viral gene sequences, vector dynamics and human dengue cases in Guangzhou, China, together with a 36-year urban environmental change maps investigated by spatiotemporal satellite image fusion. The dengue epidemics in Guangzhou are highly episodic and were not associated with annual rainfall over time. Our results indicate that urban environmental changes, especially variations in surface area covered by water in urban areas, can substantially alter the virus population and dengue transmission. The recent severe dengue outbreaks in Guangzhou may be due to the surge in an artificial lake construction, which could increase infection force between vector (mainly Aedes albopictus) and host when urban water area significantly increased. Impacts of urban environmental change on dengue dynamics may not have been thoroughly investigated in the past studies and more work needs to be done to better understand the consequences of urbanization processes in our changing world. - Highlights: • Urban dengue outbreak is associated with water area in Guangzhou, 1978–2014. • Surface water area can alter population size of dengue virus in urban area. • Urban dengue outbreak is not associated with annual rainfall in Guangzhou. • Spatiotemporal satellite image fusion can investigate urban environmental change. • Urban environmental change could induce virus, vector, and dengue epidemic change.

  3. Potential effects of groundwater and surface water contamination in an urban area, Qus City, Upper Egypt

    Science.gov (United States)

    Abdalla, Fathy; Khalil, Ramadan

    2018-05-01

    The potential effects of anthropogenic activities, in particular, unsafe sewage disposal practices, on shallow groundwater in an unconfined aquifer and on surface water were evaluated within an urban area by the use of hydrogeological, hydrochemical, and bacteriological analyses. Physicochemical and bacteriological data was obtained from forty-five sampling points based on33 groundwater samples from variable depths and 12 surface water samples. The pollution sources are related to raw sewage and wastewater discharges, agricultural runoff, and wastewater from the nearby Paper Factory. Out of the 33 groundwater samples studied, 17 had significant concentrations of NO3-, Cl- and SO42-, and high bacteria counts. Most of the water samples from the wells contained high Fe, Mn, Pb, Zn, Cd, and Cr. The majority of surface water samples presented high NO3- concentrations and high bacteria counts. A scatter plot of HCO3- versus Ca indicates that 58% of the surface water samples fall within the extreme contamination zone, while the others are within the mixing zone; whereas 94% of groundwater samples showed evidence of mixing between groundwater and wastewater. The bacteriological assessment showed that all measured surface and groundwater samples contained Escherichia coli and total coliform bacteria. A risk map delineated four classes of contamination, namely, those sampling points with high (39.3%), moderate (36.3%), low (13.3%), and very low (11.1%) levels of contamination. Most of the highest pollution points were in the middle part of the urban area, which suffers from unmanaged sewage and industrial effluents. Overall, the results demonstrate that surface and groundwater in Qus City are at high risk of contamination by wastewater since the water table is shallow and there is a lack of a formal sanitation network infrastructure. The product risk map is a useful tool for prioritizing zones that require immediate mitigation and monitoring.

  4. Continued decrease of open surface water body area in Oklahoma during 1984-2015.

    Science.gov (United States)

    Zou, Zhenhua; Dong, Jinwei; Menarguez, Michael A; Xiao, Xiangming; Qin, Yuanwei; Doughty, Russell B; Hooker, Katherine V; David Hambright, K

    2017-10-01

    Oklahoma contains the largest number of manmade lakes and reservoirs in the United States. Despite the importance of these open surface water bodies to public water supply, agriculture, thermoelectric power, tourism and recreation, it is unclear how these water bodies have responded to climate change and anthropogenic water exploitation in past decades. In this study, we used all available Landsat 5 and 7 images (16,000 scenes) from 1984 through 2015 and a water index- and pixel-based approach to analyze the spatial-temporal variability of open surface water bodies and its relationship with climate and water exploitation. Specifically, the areas and numbers of four water body extents (the maximum, year-long, seasonal, and average extents) were analyzed to capture variations in water body area and number. Statistically significant downward trends were found in the maximum, year-long, and annual average water body areas from 1984 through 2015. Furthermore, these decreases were mainly attributed to the continued shrinking of large water bodies (>1km 2 ). There were also significant decreases in maximum and year-long water body numbers, which suggested that some of the water bodies were vanishing year by year. However, remarkable inter-annual variations of water body area and number were also found. Both water body area and number were positively related to precipitation, and negatively related to temperature. Surface water withdrawals mainly influenced the year-long water bodies. The smaller water bodies have a higher risk of drying under a drier climate, which suggests that small water bodies are more vulnerable under climate-warming senarios. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Highly exposed surface area of {001} facets dominated BiOBr nanosheets with enhanced visible light photocatalytic activity.

    Science.gov (United States)

    Duan, Fang; Wang, Xiaofeng; Tan, Tingting; Chen, Mingqing

    2016-02-17

    Two groups of BiOBr nanosheets with different sizes and similar exposure percentages of {001} facets were selectively synthesized by simple hydrothermal methods. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectroscopy (DRS). The photocatalytic activity was estimated from the degradation of organic pollutants under visible-light irradiation. The results indicated that BiOBr nanosheets with similar exposure percentages of {001} facets but smaller sizes exhibited higher photocatalytic activity. Furthermore, the effects of the size, including the thickness and length, of BiOBr nanosheets were also studied. The results showed that the impact of thickness was more significant than that of length. It was found that reducing the thickness of BiOBr nanosheets can significantly increase the exposed surface areas of {001} facets (S{001}), but not necessarily the exposure percentage of {001} facets. Moreover, in our experiment, the photocatalytic activity of BiOBr nanosheets increased linearly with an increase in S{001} in the range of 0.022 to 0.111 nm(-1). Therefore, the photocatalytic activity of BiOBr nanosheets depended on the exposed surface areas of {001} facets rather than the exposure percentage of {001} facets. The enhancement of the photocatalytic activity of ultrathin BiOBr nanosheets with large exposed surface areas of {001} facets can be mainly ascribed to their enhanced absorption of visible light and improved separation efficiency of charge carriers.

  6. Adsorption and correlations of selected aromatic compounds on a KOH-activated carbon with large surface area.

    Science.gov (United States)

    Yang, Kun; Zhu, Lianghong; Yang, Jingjing; Lin, Daohui

    2018-03-15

    Knowledge of adsorption mechanism and behavior of organic compounds by KOH-activated carbons (KOH-ACs) from wastewater is crucial to its environmental application in wastewater treatment as adsorbent. A superior adsorbent, KOH-activated carbon (KOH-AC), with large surface area (3143m 2 /g), total pore volume of 2.03cm 3 /g, relatively low micropore fraction of 53.2%, and having adsorption capacities of organic compounds up to >1000mg/g, was prepared. It is an adsorbent significantly different with common ACs because the molecular sieving effect, widely observed for common ACs, is insignificant for KOH-AC. This difference could be attributed to the lower micropore fraction of KOH-AC than common ACs. A negative relationship of adsorption capacity of 25 aromatic compounds (including phenols, anilines, nitrobenzenes and polycyclic aromatic hydrocarbons) with chemical melting point was observed, suggesting that adsorption is dependent on the packing efficiency and stacking density of molecules on KOH-AC. A linear solvation energy relationships of adsorption affinity of 25 aromatic compounds with solute solvatochromic parameters was also observed, that can be used to quantify the contributions of π-π interaction, hydrogen-bonding interaction and hydrophobic effect to adsorption on KOH-AC. Combined with the reported results of adsorption of organic compounds on carbon nanotubes and biochars, it was also observed that external surface area of adsorbents is controlling the packing efficiency and stacking density of molecules on adsorbents and thus affecting adsorption capacity of organic compounds. Moreover, micropore surface area and the fraction of micropores are the adsorbent properties mainly affecting adsorption affinity of organic compounds. The observations and the developed correlations in this study would be helpful in the application of KOH-AC as superior adsorbent by enhancing the understanding of adsorption mechanisms of organic compounds on KOH-AC and by

  7. Cytotoxicity Induced by Engineered Silver Nanocrystallites Is Dependent on Surface Coatings and Cell Types

    Energy Technology Data Exchange (ETDEWEB)

    Suresh, Anil K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biosciences Division; Pelletier, Dale A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biosciences Division; Wang, Wei [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division; Morrell-Falvey, Jennifer L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biosciences Division; Gu, Baohua [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division; Doktycz, Mitchel J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biosciences Division; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS)

    2012-01-04

    Due to their unique antimicrobial properties silver nanocrystallites have garnered substantial recognition and are used extensively in biomedical applications such as wound dressing, surgical instruments and as bone substitute material. They are also released into unintended locations such as the environment or biosphere. Therefore it is imperative to understand the potential interactions, fate and transport of nanoparticles with environmental biotic systems. Although numerous factors including the composition, size, shape, surface charge and capping molecule of nanoparticles are known to influence the cell cytotoxicity, our results demonstrate for the first time that surface coatings are a major determinant in eliciting the potential cytotoxicity and cell interactions of silver nanoparticles. In the present investigation, silver nanocrystallites with nearly uniform size and shape distribution but with different surface coatings, imparting overall high negativity to high positivity, were synthesized. These nanoparticles were poly (diallyldimethylammonium) chloride-Ag, biogenic-Ag, colloidal-Ag (uncoated) and oleate-Ag with zeta potentials +45±5 mV, -12± 2 mV, -42±5 mV and -45±5 mV respectively; the particles were thoroughly purified so as to avoid false cytotoxicity interpretations. A systematic investigation on the cytotoxic effects, cellular response and membrane damage caused by these four different silver nanoparticles were evaluated using multiple toxicity measurements on mouse macrophage (RAW-264.7) and lung epithelial (C-10) cell lines. From a toxicity perspective, our results clearly indicated that the cytotoxicity was depend on various factors such as synthesis procedure, surface coat or surface charge and the cell-type for the different silver nanoparticles that were investigated. Finally, poly (diallyldimethylammonium) chloride -Ag was found to be the most toxic, followed by biogenic-Ag and oleate-Ag, whereas uncoated-Ag was found to be least toxic

  8. Temperature-dependent conformational change of PNIPAM grafted chains at high surface density in water.

    Energy Technology Data Exchange (ETDEWEB)

    Satija, Sushil K. (National Institute of Standards and Technology, Gaithersburg, MD); Mendez, Sergio (University of New Mexico, Albuquerque, NM); Balamurugan, Sreelatha S. (University of New Mexico, Albuquerque, NM); Balamurugan, Subramanian (University of New Mexico, Albuquerque, NM); Kent, Michael Stuart; Yim, Hyun; Lopez, Gabriel P. (University of New Mexico, Albuquerque, NM)

    2003-07-01

    1500 {angstrom}. More recently, Balamurugan et al. used surface plasmon resonance (SPR) to probe conformational changes in a PNIPAM brush grafted onto a gold layer by atom transfer radical polymerization (ATRP). For a sample with a dry film thickness of 517 {angstrom}, the SPR measurements indicated a significant contraction (extension of the layer with increasing/decreasing) temperature through the transition. Quantification of the change in profile characteristics was not reported, but it was noted that the change in the SPR signal occurred over a much broader range of temperature (15-35 C) than is typical of the transition for free chains in bulk solution. No systematic study of detailed PNIPAM chain conformations has yet been reported as a function of the two critical brush parameters, the surface density and molecular weight. A recent theoretical analysis by Baulin and Halperin has identified the surface density as a critical parameter demarcating different regimes of behavior. This arises from the concentration dependence of the Flory {chi} parameter as obtained from a recent phase behavior study of free chains in solution. Little attention has been paid to the surface density in previous experimental studies of grafted PNIPAM chains. We have begun a systematic study of the temperature-dependent conformational changes of PNIPAM grafted chains in water as a function of surface density and molecular weight using neutron reflection (NR). In previous work, we investigated the conformational changes of PNIPAM chains tethered to silicon oxide using two methods. The first was the 'grafting from' method in which N-isopropylacrylamide monomers were polymerized from the silicon surface with a chain transfer, free-radical technique. In the second method, preformed PNIPAM chains with carboxylic acid end groups associated with terminal hydroxyl groups of a mixed self-assembling monolayer. Detailed concentration profiles of the PNIPAM brushes were determined in D

  9. Decadal changes of surface elevation over permafrost area estimated using reflected GPS signals

    Science.gov (United States)

    Liu, Lin; Larson, Kristine M.

    2018-02-01

    Conventional benchmark-based survey and Global Positioning System (GPS) have been used to measure surface elevation changes over permafrost areas, usually once or a few times a year. Here we use reflected GPS signals to measure temporal changes of ground surface elevation due to dynamics of the active layer and near-surface permafrost. Applying the GPS interferometric reflectometry technique to the multipath signal-to-noise ratio data collected by a continuously operating GPS receiver mounted deep in permafrost in Barrow, Alaska, we can retrieve the vertical distance between the antenna and reflecting surface. Using this unique kind of observables, we obtain daily changes of surface elevation during July and August from 2004 to 2015. Our results show distinct temporal variations at three timescales: regular thaw settlement within each summer, strong interannual variability that is characterized by a sub-decadal subsidence trend followed by a brief uplift trend, and a secular subsidence trend of 0.26 ± 0.02 cm year-1 during 2004 and 2015. This method provides a new way to fully utilize data from continuously operating GPS sites in cold regions for studying dynamics of the frozen ground consistently and sustainably over a long time.

  10. Cryptic oxygen oases: Hypolithic photosynthesis in hydrothermal areas and implications for Archean surface oxidation

    Science.gov (United States)

    Havig, J. R.; Hamilton, T. L.

    2017-12-01

    Mounting geochemical evidence suggests microorganisms capable of oxygenic photosynthesis (e.g., Cyanobacteria) colonized Archean continental surfaces, driving oxidative weathering of detrital pyrites prior to the 2.5 Ga great oxidation event. Modern terrestrial environments dominated by single-celled phototrophs include hydrothermal systems (e.g., Yellowstone National Park) and hypolithic communities found in arid to hyper-arid deserts (e.g., McMurdo Dry Valleys of Antarctica, Atacama Desert of Chile). Recent work indicates terrestrial hydrothermal systems date back at least as far as 3.5 Ga. Here, we explore phototrophic communities in both hypolithic (sub-sinter) and hydrothermal (subaqueous and subaerial) environments in Yellowstone National Park as potential analogs to Archean continental surfaces. Hydrothermal sub-sinter environments provide ideal conditions for phototrophic microbial communities, including blocking of harmful UV radiation, trapping and retention of moisture, and protection from erosion by rain and surface runoff. Hypolithic communities in geothermal settings were similar in both composition and carbon uptake rates to nearby hot spring communities. We hypothesize that hydrothermal area hypolithic communities represent modern analogs of phototrophic microbial communities that colonized Archean continental surfaces, producing oxygen locally and facilitating microbially-mediated pyrite oxidation prior to the presence of free oxygen in the global atmosphere. These results have implications for oxidation of the early Earth surface, the search for biosignatures in the rock record, as well as for potential harbors of past life on Mars and the search for life on Exoplanets.

  11. Correlation between surface reconstruction and polytypism in InAs nanowire selective area epitaxy

    Science.gov (United States)

    Liu, Ziyang; Merckling, Clement; Rooyackers, Rita; Richard, Olivier; Bender, Hugo; Mols, Yves; Vila, María; Rubio-Zuazo, Juan; Castro, Germán R.; Collaert, Nadine; Thean, Aaron; Vandervorst, Wilfried; Heyns, Marc

    2017-12-01

    The mechanism of widely observed intermixing of wurtzite and zinc-blende crystal structures in InAs nanowire (NW) grown by selective area epitaxy (SAE) is studied. We demonstrate that the crystal structure in InAs NW grown by SAE can be controlled using basic growth parameters, and wurtzitelike InAs NWs are achieved. We link the polytypic InAs NWs SAE to the reconstruction of the growth front (111)B surface. Surface reconstruction study of InAs (111) substrate and the following homoepitaxy experiment suggest that (111) planar defect nucleation is related to the (1 × 1) reconstruction of InAs (111)B surface. In order to reveal it more clearly, a model is presented to correlate growth temperature and arsenic partial pressure with InAs NW crystal structure. This model considers the transition between (1 × 1) and (2 × 2) surface reconstructions in the frame of adatom atoms adsorption/desorption, and the polytypism is thus linked to reconstruction quantitatively. The experimental data fit well with the model, which highly suggests that surface reconstruction plays an important role in the polytypism phenomenon in InAs NWs SAE.

  12. Corrective Action Decision Document for Corrective Action Unit 417: Central Nevada Test Area Surface, Nevada

    International Nuclear Information System (INIS)

    1999-01-01

    This Corrective Action Decision Document (CADD) identifies and rationalizes the U.S. Department of Energy, Nevada Operations Office's selection of a recommended corrective action alternative (CAA) appropriate to facilitate the closure of Corrective Action Unit (CAU) 417: Central Nevada Test Area Surface, Nevada, under the Federal Facility Agreement and Consent Order. Located in Hot Creek Valley in Nye County, Nevada, and consisting of three separate land withdrawal areas (UC-1, UC-3, and UC-4), CAU 417 is comprised of 34 corrective action sites (CASs) including 2 underground storage tanks, 5 septic systems, 8 shaker pad/cuttings disposal areas, 1 decontamination facility pit, 1 burn area, 1 scrap/trash dump, 1 outlier area, 8 housekeeping sites, and 16 mud pits. Four field events were conducted between September 1996 and June 1998 to complete a corrective action investigation indicating that the only contaminant of concern was total petroleum hydrocarbon (TPH) which was found in 18 of the CASs. A total of 1,028 samples were analyzed. During this investigation, a statistical approach was used to determine which depth intervals or layers inside individual mud pits and shaker pad areas were above the State action levels for the TPH. Other related field sampling activities (i.e., expedited site characterization methods, surface geophysical surveys, direct-push geophysical surveys, direct-push soil sampling, and rotosonic drilling located septic leachfields) were conducted in this four-phase investigation; however, no further contaminants of concern (COCs) were identified. During and after the investigation activities, several of the sites which had surface debris but no COCs were cleaned up as housekeeping sites, two septic tanks were closed in place, and two underground storage tanks were removed. The focus of this CADD was to identify CAAs which would promote the prevention or mitigation of human exposure to surface and subsurface soils with contaminant

  13. Investigation on the growth of DAST crystals of large surface area for THz applications

    International Nuclear Information System (INIS)

    Vijay, R. Jerald; Melikechi, N.; Thomas, Tina; Gunaseelan, R.; Arockiaraj, M. Antony; Sagayaraj, P.

    2012-01-01

    Graphical abstract: It is evident from the photographs that the crystal tend to grow as a needle (Fig. 1a) in the lower concentration region (2–3 g/200 mL); whereas, in the high concentration region (5 g/200 mL) though there is a marked enlargement in the size of the crystal, the morphology of the resulting DAST crystal is slightly irregular (Fig. 1d) in nature. Among the four concentrations employed, best result was obtained with the DAST–methanol solution of concentration 4 g/200 mL; which resulted in the DAST crystal of large surface area (270 mm 2 ) with high transparency and nearly square shape (Fig. 1c) in a growth period of 20–25 days. Highlights: ► DAST crystals of different sizes are obtained for different concentrations. ► The main focus is to grow DAST crystals with large surface area. ► Structural, optical, thermal and mechanical properties are investigated. - Abstract: The growth of high quality 4-N,N-dimethylamino-4-N-methyl-stilbazoliumtosylate (DAST) crystal with large surface area is reported by adopting the slope nucleation coupled slow evaporation method (SNM-SE). The structure and composition of the crystal are studied by single crystal X-ray diffraction and CHN analyses. The linear optical properties are investigated by UV–vis absorption. The melting point and thermal behavior of DAST are investigated using differential scanning calorimetric (DSC) and thermogravimetric analyses (TGA). The Vickers microhardness number (VHN) and work hardening coefficient of the grown crystal have been determined. The surface features of the DAST crystal are analyzed by scanning electron microscopy (SEM) and it confirmed the presence of narrow line defects (NLDs) in the sample.

  14. Clay Mineralogy Studies of Soils Located on Different Geomorphic Surfaces in Jabalbarez-Jiroft Area

    Directory of Open Access Journals (Sweden)

    naser boroumand

    2017-02-01

    Full Text Available Introduction: Soil and geomorphology are closely related to each other. That is why considering geomorphic concepts in soil genesis and classification studies may cause a better understanding of soil genesis processes. Paleosols with argillic horizons were investigated on stable pediment surfaces in Jiroft area, central Iran, by Sanjari et al. (2011. They found that secondary gypsum and calcium carbonate were accumulated in mantled pediments, but moving down the slope toward lowlands, salts more soluble than gypsum have been accumulated. Clay mineralogy in soil researches helps to better studying soil genesis and development. A quantitative and qualitative study of clay minerals together with their structural composition provides valuable data on the absorption, fixation, and desorption of different cations in soils. Smectite, chlorite, illite, vermiculite, kaolinite, palygorskite, and sepiolite were reported as dominant clay minerals found in arid and semi-arid areas. The objectives of the present study are to evaluate the clay mineralogy of Jabalbarez-Jiroft soils on different geomorphic surfaces. Materials and Methods: The study area was located in Jabalbarez, 200 Km south Kerman, Central Iran. Fig. 1 showed the exact location of study area. Soil temperature and moisture regimes of the area were thermic and aridic, respectively. Hill, rock pediment, mantled pediment and piedmont alluvial plain landforms were identified, using aerial photo interpretation, topography and geological map observation, in addition to detailed field works. Air-dried soil samples were crushed and passed through a 2-mm sieve. Routine physicochemical analyses wereperformed on the samples. Undisturbed soil samples from the Bt horizon of pedons 4, 5 and 6 were chosen for micromorphology investigations. Beside, eight samples including A and C2 horizons of pedon 1, A and Bt horizon of pedon 3, Bt and Bw horizons of pedon 4, and Bt and C horizon of pedon 5 were selected for

  15. The Complete Solution of Fick's Second Law of Diffusion with Time-dependent Diffusion Coefficient and Surface Concentration

    DEFF Research Database (Denmark)

    Mejlbro, Leif

    1996-01-01

    Fick's Second Law of Diffusion with time-dependent diffusioncoefficient and surface concentration is solved. Mimicking the classicalsolution, special time-dependent surface concentration functions areconsidered. These models are used in giving estimates of the lifetimeof the structure, when the c...... the concrete cover is given, as well as estimatesof the thickness of the concrete cover, when the expected lifetime is given.*Note: Book tilte: Durability of Concrete in Saline Environment...

  16. Planetary gyre, time-dependent eddies, torsional waves, and equatorial jets at the Earth's core surface

    DEFF Research Database (Denmark)

    Gillet, N.; Jault, D.; Finlay, Chris

    2015-01-01

    We report a calculation of time-dependent quasi-geostrophic core flows for 1940–2010. Inverting recursively for an ensemble of solutions, we evaluate the main source of uncertainties, namely, the model errors arising from interactions between unresolved core surface motions and magnetic fields...... between the magnetic field and subdecadal nonzonal motions within the fluid outer core. Both the zonal and the more energetic nonzonal interannual motions were particularly intense close to the equator (below 10∘ latitude) between 1995 and 2010. We revise down the amplitude of the decade fluctuations...... of the planetary-scale circulation and find that electromagnetic core-mantle coupling is not the main mechanism for angular momentum exchanges on decadal time scales if mantle conductance is 3 × 108 S or lower....

  17. Modeling of a Curvilinear Planar Crack with a Curvature-Dependent Surface Tension

    KAUST Repository

    Zemlyanova, A. Y.

    2012-01-01

    An approach to modeling fracture incorporating interfacial mechanics is applied to the example of a curvilinear plane strain crack. The classical Neumann boundary condition is augmented with curvature-dependent surface tension. It is shown that the considered model eliminates the integrable crack-tip stress and strain singularities of order 1/2 present in the classical linear fracture mechanics solutions, and also leads to the sharp crack opening that is consistent with empirical observations. Unlike for the case of a straight crack, for a general curvilinear crack some components of the stresses and the derivatives of the displacements may still possess weaker singularities of a logarithmic type. Generalizations of the present study that lead to complete removal of all crack-tip singularities, including logarithmic, are the subject of a future paper. © 2012 Society for Industrial and Applied Mathematics.

  18. Simulation of time-dependent free-surface Navier-Stokes flows

    International Nuclear Information System (INIS)

    Muldowney, G.P.

    1989-01-01

    Two numerical methods for simulation of time-dependent free-surface Navier-Stokes flows are developed. Both techniques are based on semi-implicit time advancement of the momentum equations, integral formulation of the spatial problem at each timestep, and spectral-element discretization to solve the resulting integral equation. Central to each algorithm is a boundary-specific solution step which permits the spatial treatment in two dimensions to be performed in O(N 3 ) operations per timestep despite the presence of deforming geometry. The first approach is a domain-integral formulation involving integrals over the entire flow domain of kernel functions which arise in time-differencing the Navier-Stokes equations. The second is a particular-solution formulation which replaces domain integration with an iterative scheme to generate particular velocity and pressure fields on individual elements, followed by a patching step to produce a particular solution continuous over the full domain. Two of the most difficult aspects of viscous free-surface flow simulations, namely time-dependent geometry and nontrivial boundary conditions, are well accommodated by these integral equation techniques. In addition the methods offer spectral accuracy in space and admit arbitrarily high-order discretization in time. For large-scale computations and/or long-term time advancement the domain-integral algorithm must be executed on a supercomputer to deliver results in reasonable processing time. A detailed simulation of gas liquid flow with full resolution of the free phase boundary requires approximately five CPU hours at 80 megaflops

  19. FreeSASA: An open source C library for solvent accessible surface area calculations [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Simon Mitternacht

    2016-02-01

    Full Text Available Calculating solvent accessible surface areas (SASA is a run-of-the-mill calculation in structural biology. Although there are many programs available for this calculation, there are no free-standing, open-source tools designed for easy tool-chain integration. FreeSASA is an open source C library for SASA calculations that provides both command-line and Python interfaces in addition to its C API. The library implements both Lee and Richards’ and Shrake and Rupley’s approximations, and is highly configurable to allow the user to control molecular parameters, accuracy and output granularity. It only depends on standard C libraries and should therefore be easy to compile and install on any platform. The library is well-documented, stable and efficient. The command-line interface can easily replace closed source legacy programs, with comparable or better accuracy and speed, and with some added functionality.

  20. Applicability of the Guggenheim–Anderson–Boer water vapour sorption model for estimation of soil specific surface area

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Møldrup, Per

    2018-01-01

    Soil specific surface area (SA) controls fundamental soil processes such as retention of water, ion exchange, and adsorption and release of plant nutrients and contaminants. Conventional methods for determining SA include adsorption of polar or non‐polar fluid molecules with associated advantages...... parameters varied depending on the water activity or relative humidity range of measured data (0.03–0.93 compared with 0.10–0.80), whereas the variation for desorption was minimal. For desorption isotherms, the average water activity value at which the GAB monolayer parameter was obtained was 0......‐based modelling approaches to determine SA. Measured water vapour adsorption and desorption isotherms for 321 soil samples were used to parameterize the GAB model, the Brunauer–Emmet–Teller (BET) equation and a film adsorption Tuller–Or (TO) model to estimate SA. For adsorption isotherms, the values of the GAB...

  1. Influence of Alkali Treatment on the Surface Area of Aluminium Dross

    Directory of Open Access Journals (Sweden)

    N. S. Ahmad Zauzi

    2016-01-01

    Full Text Available Aluminium dross is an industrial waste from aluminium refining industry and classified as toxic substances. However, the disposal of dross as a waste is a burden to aluminium manufacturer industries due to its negative effects to the ecosystem, surface, and ground water. Therefore the purpose of this study is to evaluate the influence of sodium hydroxide (NaOH on the surface area and pore size of aluminium dross. There were 3 stages in the treatment activities, which were leaching, precipitation, and calcination process. The optimum result from this study was the surface area of aluminium dross increases from 10.1 m2/g up to 80.0 m2/g at 40°C, 1% NaOH, and 15-minute reaction time. Thus, aluminium dross has a potential to be converted into other useful material such as catalyst and absorbent. The benefit of this research is that the hazardous industrial waste can be turned into wealth to be used in other applications such as in catalytic activities and absorber in waste water treatment. Further investigation on the physicochemical of aluminium dross with different acid or alkali should be conducted to get deeper understanding on the aluminium dross as a catalyst-type material.

  2. Soluble and immobilized graphene oxide activates complement system differently dependent on surface oxidation state.

    Science.gov (United States)

    Wibroe, Peter P; Petersen, Søren V; Bovet, Nicolas; Laursen, Bo W; Moghimi, S Moein

    2016-02-01

    Graphene oxide (GO) is believed to become applicable in biomedical products and medicine, thereby necessitating appropriate safety evaluation dependent on their applications and the route of administration. We have examined the effect of GO form (in solution versus immobilized) and oxidation state on two related elements of innate immunity: the complement system and interleukin-6 (IL-6) release in human blood. In solution, there was a decrease in GO-mediated complement activation with decreasing surface oxygen content (and altered oxygen functionality), whereas with immobilized GO complement response were reversed and increased with decreasing oxygen content. GO solutions, at concentrations below complement activating threshold, did not induce IL-6 release from human blood leukocytes, and further dampened lipopolysaccharide-induced IL-6 release in the whole blood. The latter effect became more profound with GO's having higher oxygen content. This protective role of GO solutions, however, disappeared at higher concentrations above complement-activating threshold. We discuss these results in relation to GO surface structure and properties, and implications for local administration and development of GO-based implantable devices. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Molecular weight-dependent degradation and drug release of surface-eroding poly(ethylene carbonate).

    Science.gov (United States)

    Bohr, Adam; Wang, Yingya; Harmankaya, Necati; Water, Jorrit J; Baldursdottír, Stefania; Almdal, Kristoffer; Beck-Broichsitter, Moritz

    2017-06-01

    Poly(ethylene carbonate) (PEC) is a unique biomaterial showing significant potential for controlled drug delivery applications. The current study investigated the impact of the molecular weight on the biological performance of drug-loaded PEC films. Following the preparation and thorough physicochemical characterization of diverse PEC (molecular weights: 85, 110, 133, 174 and 196kDa), the degradation and drug release behavior of rifampicin- and bovine serum albumin-loaded PEC films was investigated in vitro (in the presence and absence of cholesterol esterase), in cell culture (RAW264.7 macrophages) and in vivo (subcutaneous implantation in rats). All investigated samples degraded by means of surface erosion (mass loss, but constant molecular weight), which was accompanied by a predictable, erosion-controlled drug release pattern. Accordingly, the obtained in vitro degradation half-lives correlated well with the observed in vitro half-times of drug delivery (R 2 =0.96). Here, the PEC of the highest molecular weight resulted in the fastest degradation/drug release. When incubated with macrophages or implanted in animals, the degradation rate of PEC films superimposed the results of in vitro incubations with cholesterol esterase. Interestingly, SEM analysis indicated a distinct surface erosion process for enzyme-, macrophage- and in vivo-treated polymer films in a molecular weight-dependent manner. Overall, the molecular weight of surface-eroding PEC was identified as an essential parameter to control the spatial and temporal on-demand degradation and drug release from the employed delivery system. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Dependence of the cyanobacterium Prochlorococcus on hydrogen peroxide scavenging microbes for growth at the ocean's surface.

    Directory of Open Access Journals (Sweden)

    J Jeffrey Morris

    2011-02-01

    Full Text Available The phytoplankton community in the oligotrophic open ocean is numerically dominated by the cyanobacterium Prochlorococcus, accounting for approximately half of all photosynthesis. In the illuminated euphotic zone where Prochlorococcus grows, reactive oxygen species are continuously generated via photochemical reactions with dissolved organic matter. However, Prochlorococcus genomes lack catalase and additional protective mechanisms common in other aerobes, and this genus is highly susceptible to oxidative damage from hydrogen peroxide (HOOH. In this study we showed that the extant microbial community plays a vital, previously unrecognized role in cross-protecting Prochlorococcus from oxidative damage in the surface mixed layer of the oligotrophic ocean. Microbes are the primary HOOH sink in marine systems, and in the absence of the microbial community, surface waters in the Atlantic and Pacific Ocean accumulated HOOH to concentrations that were lethal for Prochlorococcus cultures. In laboratory experiments with the marine heterotroph Alteromonas sp., serving as a proxy for the natural community of HOOH-degrading microbes, bacterial depletion of HOOH from the extracellular milieu prevented oxidative damage to the cell envelope and photosystems of co-cultured Prochlorococcus, and facilitated the growth of Prochlorococcus at ecologically-relevant cell concentrations. Curiously, the more recently evolved lineages of Prochlorococcus that exploit the surface mixed layer niche were also the most sensitive to HOOH. The genomic streamlining of these evolved lineages during adaptation to the high-light exposed upper euphotic zone thus appears to be coincident with an acquired dependency on the extant HOOH-consuming community. These results underscore the importance of (indirect biotic interactions in establishing niche boundaries, and highlight the impacts that community-level responses to stress may have in the ecological and evolutionary outcomes for co

  5. Observations of orientation dependence of surface morphology in tungsten implanted by low energy and high flux D plasma

    DEFF Research Database (Denmark)

    Xu, H.Y.; Zhang, Yubin; Yuan, Y.

    2013-01-01

    Surface modification by formation of blistering and nanostructures with pronounced orientation dependence has been observed on surfaces of rolled tungsten and recrystallized tungsten after exposure to a low energy (38 eV) deuterium (D) plasma with a high flux of 1024 m-2 s -1. The correlation bet...

  6. Characteristics of surface O{sub 3} over Qinghai Lake area in Northeast Tibetan Plateau, China

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Zhenxing, E-mail: zxshen@mail.xjtu.edu.cn [Department of Environmental Sciences and Engineering, Xi' an Jiaotong University, Xi' an (China); Key Lab of Aerosol, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi' an (China); Cao, Junji [Key Lab of Aerosol, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi' an (China); Zhang, Leiming [Air Quality Research Division, Environment Canada, Toronto (Canada); Zhao, Zhuzi [Key Lab of Aerosol, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi' an (China); Dong, Jungang [School of Architecture, Xi' an University of Architecture and Technology, Xi' an 710055 (China); Wang, Linqing [Department of Environmental Sciences and Engineering, Xi' an Jiaotong University, Xi' an (China); Wang, Qiyuan; Li, Guohui; Liu, Suixin [Key Lab of Aerosol, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi' an (China); Zhang, Qian [Department of Environmental Sciences and Engineering, Xi' an Jiaotong University, Xi' an (China)

    2014-12-01

    Surface O{sub 3} was monitored continuously during Aug. 12, 2010 to Jul. 21, 2011 at a high elevation site (3200 m above sea level) in Qinghai Lake area (36°58′37″N, 99°53′56″E) in Northeast Tibetan Plateau, China. Daily average O{sub 3} ranged from 21.8 ppbv to 65.3 ppbv with an annual average of 41.0 ppbv. Seasonal average of O{sub 3} followed a decreasing order of summer > autumn > spring > winter. Diurnal variations of O{sub 3} showed low concentrations during daytime and high concentrations during late night and early morning. An intensive campaign was also conducted during Aug. 13–31, 2010 to investigate correlations between meteorological or chemical conditions and O{sub 3}. It was found that O{sub 3} was poorly correlated with solar radiation due to the insufficient NO{sub x} in the ambient air, thus limiting O{sub 3} formation under strong solar radiation. In contrast, high O{sub 3} levels always coincided with strong winds, suggesting that stratospheric O{sub 3} and long range transport might be the main sources of O{sub 3} in this rural area. Back-trajectory analysis supported this hypothesis and further indicated the transport of air masses from northwest, northeast and southeast directions. - Highlights: • Surface O{sub 3} was measured in Qinghai Lake area in Northeast Tibetan Plateau, China. • The O{sub 3} chemical formation was under a strong NOx-limited in Qinghai Lake areas. • Stratospheric O{sub 3} and transport might be the main sources of O{sub 3} in this area.

  7. Characteristics of surface O3 over Qinghai Lake area in Northeast Tibetan Plateau, China

    International Nuclear Information System (INIS)

    Shen, Zhenxing; Cao, Junji; Zhang, Leiming; Zhao, Zhuzi; Dong, Jungang; Wang, Linqing; Wang, Qiyuan; Li, Guohui; Liu, Suixin; Zhang, Qian

    2014-01-01

    Surface O 3 was monitored continuously during Aug. 12, 2010 to Jul. 21, 2011 at a high elevation site (3200 m above sea level) in Qinghai Lake area (36°58′37″N, 99°53′56″E) in Northeast Tibetan Plateau, China. Daily average O 3 ranged from 21.8 ppbv to 65.3 ppbv with an annual average of 41.0 ppbv. Seasonal average of O 3 followed a decreasing order of summer > autumn > spring > winter. Diurnal variations of O 3 showed low concentrations during daytime and high concentrations during late night and early morning. An intensive campaign was also conducted during Aug. 13–31, 2010 to investigate correlations between meteorological or chemical conditions and O 3 . It was found that O 3 was poorly correlated with solar radiation due to the insufficient NO x in the ambient air, thus limiting O 3 formation under strong solar radiation. In contrast, high O 3 levels always coincided with strong winds, suggesting that stratospheric O 3 and long range transport might be the main sources of O 3 in this rural area. Back-trajectory analysis supported this hypothesis and further indicated the transport of air masses from northwest, northeast and southeast directions. - Highlights: • Surface O 3 was measured in Qinghai Lake area in Northeast Tibetan Plateau, China. • The O 3 chemical formation was under a strong NOx-limited in Qinghai Lake areas. • Stratospheric O 3 and transport might be the main sources of O 3 in this area

  8. Surface deformation of active volcanic areas retrieved with the SBAS-DInSAR technique: an overview

    Directory of Open Access Journals (Sweden)

    G. Zeni

    2008-06-01

    Full Text Available This paper presents a comprehensive overview of the surface deformation retrieval capability of the Differential Synthetic Aperture Radar Interferometry (DInSAR algorithm, referred to as Small BAseline Subset (SBAS technique, in the context of active volcanic areas. In particular, after a brief description of the algorithm some experiments relevant to three selected case-study areas are presented. First, we concentrate on the application of the SBAS algorithm to a single-orbit scenario, thus considering a set of SAR data composed by images acquired on descending orbits by the European Remote Sensing (ERS radar sensors and relevant to the Long Valley caldera (eastern California area. Subsequently, we address the capability of the SBAS technique in a multipleorbit context by referring to Mt. Etna volcano (southern Italy test site, with respect to which two different ERS data set, composed by images acquired both on ascending and descending orbits, are available. Finally, we take advantage of the capability of the algorithm to work in a multi-platform scenario by jointly exploiting two different sets of SAR images collected by the ERS and the Environment Satellite (ENVISAT radar sensors in the Campi Flegrei caldera (southern Italy area. The presented results demonstrate the effectiveness of the algorithm to investigate the deformation field in active volcanic areas and the potential of the DInSAR methodologies within routine surveillance scenario.

  9. Visualization of Lake Mead Surface Area Changes from 1972 to 2009

    Directory of Open Access Journals (Sweden)

    David M. Atkinson

    2012-06-01

    Full Text Available For most of the last decade, the south-western portion of the United States has experienced a severe and enduring drought. This has caused serious concerns about water supply and management in the region. In this research, 30 orthorectified Landsat satellite images from the United States Geological Service (USGS Earth Explorer archive were analyzed for the 1972 to 2009 period. The images encompassed Lake Mead (a major reservoir in this region and were examined for changes in water surface area. Decadal lake area minimums/maximums were achieved in 1972/1979, 1981/1988, 1991/1998, and 2009/2000. The minimum lake area extent occurred in 2009 (356.4 km2, while the maximum occurred in 1998 (590.6 km2. Variable trends in water level and lake area were observed throughout the analysis period, however progressively lower values were observed since 2000. The Landsat derived lake areas show a very strong relationship with actual measured water levels at the Hoover Dam. Yearly water level variations at the dam vary minimally from the satellite derived estimates. A complete (yearly record of satellite images may have helped to reduce the slight deviations in the time series.

  10. Estimating Surface Area of Sponges and Marine Gorgonians as Indicators of Habitat Availability on Caribbean Coral Reefs

    Science.gov (United States)

    Surface area and topographical complexity are fundamental attributes of shallow tropical coral reefs and can be used to estimate habitat for fish and invertebrates. This study presents empirical methods for estimating surface area provided by sponges and gorgonians in the Central...

  11. Groundwater impact on surface water quality and nutrient loads in lowland polder catchments: monitoring the greater Amsterdam area

    NARCIS (Netherlands)

    Yu, L.; Rozemeijer, J.; Breukelen, B.M. van; Ouboter, M.; Vlugt, C. van der; Broers, H.P.

    2018-01-01

    The Amsterdam area, a highly manipulated delta area formed by polders and reclaimed lakes, struggles with high nutrient levels in its surface water system. The polders receive spatially and temporally variable amounts of water and nutrients via surface runoff, groundwater seepage, sewer leakage, and

  12. Groundwater impacts on surface water quality and nutrient loads in lowland polder catchments : Monitoring the greater Amsterdam area

    NARCIS (Netherlands)

    Yu, Liang; Rozemeijer, Joachim; van Breukelen, B.M.; Ouboter, Maarten; Van Der Vlugt, Corné; Broers, Hans Peter

    2018-01-01

    The Amsterdam area, a highly manipulated delta area formed by polders and reclaimed lakes, struggles with high nutrient levels in its surface water system. The polders receive spatially and temporally variable amounts of water and nutrients via surface runoff, groundwater seepage, sewer leakage,

  13. Atomic layer deposition of highly dispersed Pt nanoparticles on a high surface area electrode backbone for electrochemical promotion of catalysis

    NARCIS (Netherlands)

    Hajar, Y.; di Palma, V.; Kyriakou, V.; Verheijen, M. A.; Baranova, E. A.; Vernoux, P.; Kessels, W. M. M.; Creatore, M.; van de Sanden, M. C. M.; Tsampas, M. N.

    2017-01-01

    A novel catalyst design for electrochemical promotion of catalysis (EPOC) is proposed which overcomes the main bottlenecks that limit EPOC commercialization, i.e., the low dispersion and small surface area of metal catalysts. We have increased the surface area by using a porous composite electrode

  14. Characteristics of PAHs adsorbed on street dust and the correlation with specific surface area and TOC.

    Science.gov (United States)

    Wang, Chengkun; Li, Yingxia; Liu, Jingling; Xiang, Li; Shi, Jianghong; Yang, Zhifeng

    2010-10-01

    Street dust was collected from five roads with different traffic volumes in the metropolitan area of Beijing and separated into five size fractions. Concentrations of polycyclic aromatic hydrocarbons (PAHs) adsorbed on street dust in different size ranges and their correlation with specific surface area and total organic carbon (TOC) were investigated. Results show that the concentration of 16-PAHs of sieved samples ranges from 0.27 to 1.30 mg/kg for all the sampling sites. Particles smaller than 40 mum in diameter have the highest 16-PAHs concentration among all of the size ranges for street dust from the four sampling sites with vehicles running on. PAHs with three or four rings account for 68% of the overall 16-PAHs on average. Remarkable positive correlation exists between 16-PAHs concentration and specific surface area with R(2) values from 0.7 to 0.96 for the four sampling sites with vehicles running on. The relationship between the concentration of 16-PAHs and TOC is less clear.

  15. Minimal area surfaces in AdS n+1 and Wilson loops

    Science.gov (United States)

    He, Yifei; Huang, Changyu; Kruczenski, Martin

    2018-02-01

    The AdS/CFT correspondence relates the expectation value of Wilson loops in N = 4 SYM to the area of minimal surfaces in AdS 5. In this paper we consider minimal area surfaces in generic Euclidean AdS n+1 using the Pohlmeyer reduction in a similar way as we did previously in Euclidean AdS 3. As in that case, the main obstacle is to find the correct parameterization of the curve in terms of a conformal parameter. Once that is done, the boundary conditions for the Pohlmeyer fields are obtained in terms of conformal invariants of the curve. After solving the Pohlmeyer equations, the area can be expressed as a boundary integral involving a generalization of the conformal arc-length, curvature and torsion of the curve. Furthermore, one can introduce the λ-deformation symmetry of the contours by a simple change in the conformal invariants. This determines the λ-deformed contours in terms of the solution of a boundary linear problem. In fact the condition that all λ deformed contours are periodic can be used as an alternative to solving the Pohlmeyer equations and is equivalent to imposing the vanishing of an infinite set of conserved charges derived from integrability.

  16. Monitoring of the Earth's surface deformation in the area of water dam Zarnowiec

    Science.gov (United States)

    Mojzes, Marcel; Wozniak, Marek; Habel, Branislav; Macak, Marek

    2017-04-01

    Mathematical and physical research directly motivates geodetic community which can provide very accurate measurements for testing of the proposed models Earth's surface motion near the water dams should be monitored due to the security of the area. This is a process which includes testing of existing models and their physical parameters. Change of the models can improve the practical results for analyzing the trends of motion in the area of upper reservoir of water dam Zarnowiec. Since 1998 Warsaw University of Technology realized a research focused on the horizontal displacements of the upper reservoir of water dam Zarnowiec. The 15 selected control points located on the upper reservoir crown of the water dam were monitored by classical distance measurements. It was found out that changes in the object's geometry occur due to the variation of the water level. The control measurements of the changes in the object's geometry occurring during the process of emptying and filling of the upper reservoir of water dam were compared with the deformations computed using improved Boussinesqués method programmed in the software MATLAB and ANSYS for elastic and isotropic half space as derivation of suitable potentials extended to the loaded region. The details and numerical results of this process are presented This presentation was prepared within the project "National Centre for Diagnostic of the Earth's Surface Deformations in the Area of Slovakia", ITMS code: 26220220108.

  17. A Study of Daily Living Dependency Status among Elderly in an Urban Slum area of Dehradun

    Directory of Open Access Journals (Sweden)

    Puneet Ohri

    2014-12-01

    Full Text Available Background: Population aging is observed world-wide. As per Census 2011, elderly constitutes 7.4% population of India. It is expected to increase to 20% in 2050. This segment of population faces multiple medical and psychological problems. To address and solve these problems great effort from the country and the community is required. Objective: To assess the daily living dependency status among elderly. Method:  A cross sectional study was conducted in Dehradun, among 215 elderly people, using a pre-structured questionnaire. Their activities of daily living (ADL and Instrumental activities of daily living (IADL were recorded by observation and interviewing them with their families. Results: Out of total, 93% individuals were independent in their ADLs, with more dependence in the very old elderly. Maximum inability was found in Bathing and dressing. 70.7% elderly were dependent on one or more IADLs, female elderly being more dependent than male (p<0.05. However there was no significant difference of dependence in the male and female elderly in performing ADLs. Education and socio-economic status had a positive effect on independence in IADLs. Among all IADLs male elderly showed a maximum dependency for cooking and laundry while females showed a greater dependency in using telephone, managing money and travelling.

  18. The importance of the active surface area of graphite materials in the first lithium intercalation

    Energy Technology Data Exchange (ETDEWEB)

    Novak, P.; Ufheil, J.; Buqa, H. [Paul Scherrer Institut, Electrochemistry Laboratory, CH-5232 Villigen PSI (Switzerland); Krumeich, F. [ETH Zuerich, Laboratory of Inorganic Chemistry, CH-8093 Zurich (Switzerland); Spahr, M.E.; Goers, D.; Wilhelm, H.; Vix-Guterl, C. [TIMCAL SA, CH-6743 Bodio TI (Switzerland); Dentzer, J.; Gadiou, R. [Institut de Chimie des Surfaces et Interfaces, CNRS UPR 9069, F-68057 Mulhouse Cedex (France)

    2007-12-06

    When lithium is intercalated into graphite in ethylene carbonate (EC) containing electrolytes, solvent co-intercalation leading to the exfoliation of the graphite structure could occur. The exfoliation can be suppressed if an efficient solid electrolyte interphase (SEI, a passivation layer) is formed. Here we study the role played by the active surface area (ASA) of graphite materials during their first electrochemical reduction. ASA (related to the presence of defects at the carbon surface) appears as a critical graphite surface parameter influencing the surface passivation mechanism and the graphite exfoliation. The ASA of TIMREX {sup registered} SLX50 synthetic graphite was modified by thermal treatment in argon and air. The electrochemical performance was characterized in 1 M LiPF{sub 6}, EC:DMC electrolyte and post mortem analyses were performed by SEM imaging. It turned out that a decrease of the graphite ASA, i.e., an increase of the graphite structural order, hinders the formation of the passivation layer and favors the exfoliation process. In contrast, the exfoliation of the same graphite can be suppressed if its ASA is increased for example by air treatment. The ASA of the graphite kinetically controls the formation of an efficient SEI film and accordingly the irreversible charge loss is much lower in the case of graphite with a high ASA value. (author)

  19. Blasting injuries in surface mining with emphasis on flyrock and blast area security

    Energy Technology Data Exchange (ETDEWEB)

    Bajpayee, T.S.; Rehak, T.R.; Mowrey, G.L.; Ingram, D.K. [NIOSH, Pittsburgh, PA (USA). Pittsburgh Research Lab.

    2004-07-01

    Blasting is a hazardous component of surface mining. Serious injuries and fatalities result from improper judgment or practice during rock blasting. This paper describes several fatal injury case studies, analyzes causative factors, and emphasizes preventive measures. During the 21-year period from 1978 to 1998, the mean yearly explosive-related injuries (fatal and nonfatal) for surface coal mines was 8.86 (95% CI: 6.38-11.33), and for surface metal/nonmetal mines 10.76 (95% CI: 8.39-13.14). Flyrock and lack of blast area security accounted for 68.2% of these injuries. Case studies indicate that the causative factors for fatal injuries are primarily personal and task-related and to some extent environmental. A reduction in the annual injuries in surface coal mines was observed during the 10-year period of 1989-1998 (5.80 (95% CI: 2.71-8.89)) compared to the previous 10-year period of 1979-1988 (10.90 (95% CI: 7.77-14.14)). However, such reduction was not noticed in the metal/nometal sector (i.e., 9.30 (95% CI: 6.84-11.76) for the period 1989-1998 compared with 11.00 (95% CI: 7.11-14.89) for the period 1979-1988). Discussion of case studies during safety meetings will help to mitigate fatal injuries and derive important payoffs in terms of lower risks and costs of injuries.

  20. Analysis and Application of River Surface Line in Hilly Area based on Hec-ras Model

    Directory of Open Access Journals (Sweden)

    Yang Congshan

    2017-01-01

    Full Text Available For example—Cixian Fuyang River Regulation Project. Due to the character that Fuyang River is located in hilly areas of Cixian, we use the Hex-ras software to calculate the status of the river water surface line for the goal of determining the final treatment plan. We maintain the present situation of the river channel design as principle, select the most appropriate pushed water level and roughnessas the basic, and we combine the classification calculation of crossing structures of backwater and the encryption calculation section to get the more accurate result. We compare the water level elevation and the calculation of cross strait, analyze the design parameters, calculate repeated the water line section, analyze the rationality of the design plan, and then finally determine the applicability of Hex-rac software in the large continuous variation of cross section of embankment of river river surface line.

  1. GC/MS Analysis of Pesticides in the Ferrara Area (Italy) Surface Water: A Chemometric Study

    International Nuclear Information System (INIS)

    Pasti, L.; Dondi, F.; Nava, E.; Morelli, M.; Bignami, S.

    2007-01-01

    The development of a network to monitor surface waters is a critical element in the assessment, restoration and protection of water quality. In this study, concentrations of 42 pesticides - determined by GC-MS on samples from 11 points along the Ferrara area rivers - have been analyzed by chemometric tools. The data were collected over a three-year period (2002-2004). Principal component analysis of the detected pesticides was carried out in order to define the best spatial locations for the sampling points. The results obtained have been interpreted in view of agricultural land use. Time series data regarding pesticide contents in surface waters has been analyzed using the Autocorrelation function. This chemometric tool allows for seasonal trends and makes it possible to optimize sampling frequency in order to detect the effective maximum pesticide content

  2. Improved capacity to evaluate changes in intestinal mucosal surface area using mathematical modeling.

    Science.gov (United States)

    Greig, Chasen J; Cowles, Robert A

    2017-07-01

    Quantification of intestinal mucosal growth typically relies on morphometric parameters, commonly villus height, as a surrogate for presumed changes in mucosal surface area (MSA). We hypothesized that using mathematical modeling based on multiple unique measurements would improve discrimination of the effects of interventions on MSA compared to standard measures. To determine the ability of mathematical modeling to resolve differences in MSA, a mouse model with enhanced serotonin (5HT) signaling known to stimulate mucosal growth was used. 5-HT signaling is potentiated by targeting the serotonin reuptake transporter (SERT) molecule. Selective serotonin reuptake inhibitor-treated wild-type (WT-SSRI), SERT-knockout (SERTKO), and wild-type C57Bl/6 (WT) mice were used. Distal ileal sections were H&E-stained. Villus height (VH), width (VW), crypt width (CW), and bowel diameter were used to calculate surface area enlargement factor (SEF) and MSA. VH alone for SERTKO and SSRI was significantly increased compared to WT, without a difference between SERTKO and WT-SSRI. VW and CW were significantly decreased for both SERTKO and WT-SSRI compared to WT, and VW for WT-SSRI was also decreased compared to SERTKO. These changes increased SEF and MSA for SERTKO and WT-SSRI compared to WT. Additionally, SEF and MSA were significantly increased for WT-SSRI compared to SERTKO. Mathematical modeling provides a valuable tool for differentiating changes in intestinal MSA. This more comprehensive assessment of surface area does not appear to correlate linearly with standard morphometric measures and represents a more comprehensive method for discriminating between therapies aimed at increasing functional intestinal mucosa. © 2017 Wiley Periodicals, Inc.

  3. The recent hiatus in global warming of the land surface: Scale-dependent breakpoint occurrences in space and time

    Science.gov (United States)

    Ying, Lingxiao; Shen, Zehao; Piao, Shilong

    2015-08-01

    The spatial and temporal variability of the recent land warming hiatus have seldom been explored, despite their importance for understanding the mechanisms underlying the phenomenon. In this study, we applied piecewise linear regression to investigate the spatiotemporal patterns of the breakpoint time of warming over 40 years (1974-2013). Our results showed that at the global scale, mean annual temperature (MAT) over the land increased significantly until 2005 and that the warming trend then stalled. However, the breakpoint time of the warming varied greatly among different seasons and continents. We found no statistically significant breakpoint in MAT over the Northern Hemisphere, but MAT over the Southern Hemisphere showed a significant breakpoint (P < 0.001) in 1979. At the seasonal scale, only the winter season (December-January-February) showed a statistically significant breakpoint in global land temperature. The other seasons showed continuous increasing temperature during the whole study period. Our study examined the recent global warming hiatus on the land surface using an area-weighted summary of a scale-dependent phenomenon with substantial spatiotemporal heterogeneity and revealed the winter cooling in the Northern Hemisphere low-middle latitudes in 1999-2008 as the major contributor to the global warming hiatus on land surface in 2005. This result highlights the importance of using a statistical method to identify the timing of climate phase change. A better understanding of the processes behind the spatiotemporal patterns of local-scale breakpoint occurrences in land surface temperature would shed new light on the mechanisms of the recent global warming hiatus.

  4. Frontal eye field microstimulation induces task-dependent gamma oscillations in the lateral intraparietal area

    NARCIS (Netherlands)

    Premereur, Elsie; Vanduffel, Wim; Roelfsema, Pieter R.; Janssen, Peter

    2012-01-01

    Macaque frontal eye fields (FEF) and the lateral intraparietal area (LIP) are high-level oculomotor control centers that have been implicated in the allocation of spatial attention. Electrical microstimulation of macaque FEF elicits functional magnetic resonance imaging (fMRI) activations in area

  5. Frontal eye field microstimulation induces task-dependent gamma oscillations in the lateral intraparietal area

    NARCIS (Netherlands)

    Premereur, E.; Vanduffel, W.; Roelfsema, P.R.; Janssen, P.

    2012-01-01

    Macaque frontal eye fields (FEF) and the lateral intraparietal area (LIP) are high-level oculomotor control centers that have been implicated in the allocation of spatial attention. Electrical micro stimulation of macaque FEF elicits functional magnetic resonance imaging (fMRI) activations in area

  6. THE SURFACE-MEDIATED UNFOLDING KINETICS OF GLOBULAR PROTEINS IS DEPENDENT ON MOLECULAR WEIGHT AND TEMPERATURE

    Energy Technology Data Exchange (ETDEWEB)

    Patananan, A.N.; Goheen, S.C.

    2008-01-01

    The adsorption and unfolding pathways of proteins on rigid surfaces are essential in numerous complex processes associated with biomedical engineering, nanotechnology, and chromatography. It is now well accepted that the kinetics of unfolding are characterized by chemical and physical interactions dependent on protein deformability and structure, as well as environmental pH, temperature, and surface chemistry. Although this fundamental process has broad implications in medicine and industry, little is known about the mechanism because of the atomic lengths and rapid time scales involved. Therefore, the unfolding kinetics of myoglobin, β-glucosidase, and ovalbumin were investigated by adsorbing the globular proteins to non-porous cationic polymer beads. The protein fractions were adsorbed at different residence times (0, 9, 10, 20, and 30 min) at near-physiological conditions using a gradient elution system similar to that in high-performance liquid chromatography. The elution profi les and retention times were obtained by ultraviolet/visible spectrophotometry. A decrease in recovery was observed with time for almost all proteins and was attributed to irreversible protein unfolding on the non-porous surfaces. These data, and those of previous studies, fi t a positively increasing linear trend between percent unfolding after a fi xed (9 min) residence time (71.8%, 31.1%, and 32.1% of myoglobin, β-glucosidase, and ovalbumin, respectively) and molecular weight. Of all the proteins examined so far, only myoglobin deviated from this trend with higher than predicted unfolding rates. Myoglobin also exhibited an increase in retention time over a wide temperature range (0°C and 55°C, 4.39 min and 5.74 min, respectively) whereas ovalbumin and β-glucosidase did not. Further studies using a larger set of proteins are required to better understand the physiological and physiochemical implications of protein unfolding kinetics. This study confi rms that surface

  7. Fabrication of large-area hydrophobic surfaces with femtosecond-laser-structured molds

    Science.gov (United States)

    Wu, P. H.; Cheng, C. W.; Chang, C. P.; Wu, T. M.; Wang, J. K.

    2011-11-01

    Fast replication of large-area femtosecond-laser-induced surface micro/nanostructures on plastic parts by injection molding is demonstrated. An STAVAX steel mold insert is irradiated by femtosecond laser pulses with linear or circular polarization to form periodic-like nanostructures or nanostructure-covered conical microstructures. It was then used for the process of thermal injection molding. The process provides high-volume manufacturing means to generate hydrophobic enhanced plastic parts, which is expected to be widely used in consumables and chemical/biomedical device industries.

  8. Understanding the growth mechanism of carbon nanotubes via the ``cluster volume to surface area" model

    Science.gov (United States)

    Mandati, Sreekanth; Kunstmann, Jens; Boerrnert, Felix; Schoenfelder, Ronny; Ruemmeli, Mark; Kar, Kamal K.; Cuniberti, Gianaurelio

    2010-03-01

    The influence of mixed catalysts for the high yield production of carbon nanotubes (CNTs) has been studied systematically. Based on extensive experimental data a ``Catalyst Volume to Surface Area'' (CVSA) model was developed to understand the influence of the process parameters on the yield and CNT diameter distribution [1]. In our study, we present a refined version of the CVSA model developed by combining experiments and simulations. We discuss our current understanding of the growth mechanism and how the model might be used to increase CNT yields by using mixed catalysts.[4pt] [1] S. Tetali et al., ACS Nano (2009), DOI: 10.1021/nn9012548.

  9. Conventional and acoustic surface plasmons on noble metal surfaces: a time-dependent density functional theory study

    DEFF Research Database (Denmark)

    Yan, Jun; Jacobsen, Karsten W.; Thygesen, Kristian S.

    2012-01-01

    First-principles calculations of the conventional and acoustic surface plasmons (CSPs and ASPs) on the (111) surfaces of Cu, Ag, and Au are presented. The effect of s-d interband transitions on both types of plasmons is investigated by comparing results from the local density approximation...

  10. Radioecological state of some surface water systems of contaminated areas of both Gomel and Mogilev Regions

    International Nuclear Information System (INIS)

    Datskevich, P. I.; Komissariv, F. D.; Khvale', O. D.; Basharina, L. P.; Lobach, I. L.

    1997-01-01

    The radioecological situation of different ecosystems of Belarus and their components has been analysed. Such components of the surface water ecosystems as water, suspensions, sediments and soils of water-collection areas were used for the investigation of the content of cesium 137 and strontium 90. The received data were given since 1990. The content of cesium 137 and strontium 90 in the components of water ecosystems was counted in the laboratory conditions by means of standard methods of beta radiometry, semiconductor gamma spectrometry and radiochemistry. The error of measurement of radioactivity was not higher than 25 and 35% for cesium 137 and strontium 90 accordingly. Water ecosystems were distinguished by the state of contamination of water-collection areas and hydrological parameters. These and some other reasons considered in the article influence on the character of cesium 137 and strontium 90 behaviour in water ecosystems

  11. Long term change of diurnal cycle in surface air temperature over Tokyo metropolitan area

    Science.gov (United States)

    Hara, M.; Shimada, T.

    2017-12-01

    Tokyo Metropolitan area (i.e. southern part of Kanto district) is known for one of the hottest areas in summer in Japan. Especially in Saitama prefecture (north of Tokyo), the daily maximum surface air temperature (SAT) at screen height sometimes reached in 40 C. In the last decade, the summer heat environment in Japan is getting worse, and the number of emergency transportations due to heat stroke is rapidly increasing. In this study, we evaluate regional climate change due to some factors, such as land use / land cover changes. To evaluate the regional climate change, we performed analysis of observed data and a series of past climate simulations using the Weather Research and Forecasting (WRF) model with high horizontal resolution, including an urban canopy sub-model.

  12. Dose-area product and entrance surface dose in paediatric radiography

    Energy Technology Data Exchange (ETDEWEB)

    Servomaa, A.; Komppa, T.; Parviainen, T.; Heikkilae, M. [STUK - Radiation and Nuclear Safety Authority, Helsinki (Finland)

    2003-06-01

    Dose-area products (DAP) in paediatric radiography were measured in four university hospitals in Finland. The entrance surface dose (ESD) was calculated from the measured DAP value for each radiographic projection. The purpose was to combine the results with other European studies for development of diagnostic reference levels for paediatric X-ray examinations. The study included 740 paediatric patients, and a total of 1500 single projections were recorded, including 660 projections from extremities. Results were compared with recommended best practices and diagnostic reference levels for ESD. Ratios of DAP to ESD were studied to estimate the levels of DAP corresponding to recommended ESD reference levels. It is desirable for practical purposes that diagnostic reference levels for radiographic projections are also expressed in terms of dose-area product. (orig.)

  13. Surface Area Variability of a North-Central Tanzanian Crater Lake

    Directory of Open Access Journals (Sweden)

    Lindsey Higgins

    2016-06-01

    Full Text Available A history of modern (1973–2015 surface area variability for Lake Basotu in north-central Tanzania has been reconstructed using archived Landsat images from the dry season between June and October. This record was compared to local weather data as well as larger scale weather patterns. The lake has been in a state of decline interrupted by major flood events since the beginning of the satellite record. From 1973 to 1997, the lake area was between 0.97 km2 and 4.28 km2. Lake extent abruptly increased to 13.86 km2 in 1998, when a co-occurrence of El Niño and a positive Indian Ocean Dipole led to extensive flooding. It is hypothesized that local agricultural practices leading to soil erosion and subsequent basin sedimentation have most likely increased the sensitivity of Lake Basotu to climatic fluctuations.

  14. Evolution of surface topography in dependence on the grain orientation during surface thermal fatigue of polycrystalline copper

    CERN Document Server

    Aicheler, M; Taborelli, M; Calatroni, S; Neupert, H; Wuensch, W; Sgobba, S

    2011-01-01

    Surface degradation due to cyclic thermal loading plays a major role in the Accelerating Structures (AS) of the future Compact Linear Collider (CLIC) In this article results on surface degradation of thermally cycled polycrystalline copper as a function of the orientation of surface grains are presented Samples with different grain sizes were subjected to thermal fatigue using two different methods and were then characterized using roughness measurements and Orientation Imaging Scanning-Electron-Microscopy (OIM-SEM) Samples fatigued by a pulsed laser show the same trend in the orientation-fatigue damage accumulation as the sample fatigued by pulsed Radio-Frequency-heating (RF) it is clearly shown that 11 1 1] surface grains develop significantly more damage than the surface grains oriented in {[}100] and three reasons for this behaviour are pointed out Based on observations performed near grain boundaries their role in the crack initiation process is discussed The results are in good agreement with previous f...

  15. Surface water areas significantly impacted 2014 dengue outbreaks in Guangzhou, China.

    Science.gov (United States)

    Tian, Huaiyu; Huang, Shanqian; Zhou, Sen; Bi, Peng; Yang, Zhicong; Li, Xiujun; Chen, Lifan; Cazelles, Bernard; Yang, Jing; Luo, Lei; Jing, Qinlong; Yuan, Wenping; Pei, Yao; Sun, Zhe; Yue, Tianxiang; Kwan, Mei-Po; Liu, Qiyong; Wang, Ming; Tong, Shilu; Brownstein, John S; Xu, Bing

    2016-10-01

    Dengue transmission in urban areas is strongly influenced by a range of biological and environmental factors, yet the key drivers still need further exploration. To better understand mechanisms of environment-mosquito-urban dengue transmission, we propose an empirical model parameterized and cross-validated from a unique dataset including viral gene sequences, vector dynamics and human dengue cases in Guangzhou, China, together with a 36-year urban environmental change maps investigated by spatiotemporal satellite image fusion. The dengue epidemics in Guangzhou are highly episodic and were not associated with annual rainfall over time. Our results indicate that urban environmental changes, especially variations in surface area covered by water in urban areas, can substantially alter the virus population and dengue transmission. The recent severe dengue outbreaks in Guangzhou may be due to the surge in an artificial lake construction, which could increase infection force between vector (mainly Aedes albopictus) and host when urban water area significantly increased. Impacts of urban environmental change on dengue dynamics may not have been thoroughly investigated in the past studies and more work needs to be done to better understand the consequences of urbanization processes in our changing world. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  16. Alcohol and Drug Use, Abuse, and Dependence in Urban Areas and Colonias of the Texas-Mexico Border

    Science.gov (United States)

    Wallisch, Lynn S.; Spence, Richard T.

    2006-01-01

    This study describes the prevalence of alcohol and drug use, abuse, and dependence among adults on the Texas-Mexico border in 2002-2003. The findings are based on survey responses from a random sample of 1,200 adults living in households in three communities: El Paso, a densely populated city in west Texas; the less dense urbanized areas of the…

  17. Pollen deposition in tauber traps and surface soil samples in the Mar Chiquita coastal lagoon area, pampa grasslands (Argentina

    Directory of Open Access Journals (Sweden)

    Fabiana Latorre

    2010-12-01

    Full Text Available Estimations of airborne pollen loadings deposited in Tauber traps were studied in a coastal lagoon from south-eastern Pampa grasslands, Argentina, in order to assess their relationship with surface samples and to interpret the representativeness of local, regional and extraregional vegetation. Three different environments were considered: a coastal dune barrier with a psammophytic community, a salt marsh with a halophytic community in Mar Chiquita lagoon, and a freshwater community at Hinojales freshwater lake. Based on a record of surface samples taken from a previous paper, a parametric model was built to classify Tauber samples gathered from the natural vegetation communities of the study area. Results revealed that just like their surface counterparts, Tauber trap records qualitatively reflect the predominant vegetation types, although ecological groups feature different quantitative representations depending on the record type. Pollen loadings showed that airborne pollen transport was predominantly of local range, in accordance with previous results from the same study area. Airborne - surface samples relationships enrich our knowledge of the present environment that could be useful to improve paleoecological interpretations of the area.Se estimó el depósito polínico atmosférico de trampas Tauber en una laguna costera del sudeste de la estepa pampeana argentina, con el objetivo de analizar su relación con muestras de polen superficial e interpretar la representatividad de la vegetación local, regional y extraregional. Se consideraron tres ambientes diferentes: una barrera costera de dunas con vegetación psamofítica, la marisma de la laguna costera Mar Chiquita, con vegetación halofítica, y la laguna continental Hinojales, con vegetación hidrofítica. En base a las muestras de superficie y análisis de un trabajo previo, se construyó un modelo paramétrico para clasificar las muestras Tauber tomadas en la vegetación natural del

  18. Identifying grain-size dependent errors on global forest area estimates and carbon studies

    Science.gov (United States)

    Daolan Zheng; Linda S. Heath; Mark J. Ducey

    2008-01-01

    Satellite-derived coarse-resolution data are typically used for conducting global analyses. But the forest areas estimated from coarse-resolution maps (e.g., 1 km) inevitably differ from a corresponding fine-resolution map (such as a 30-m map) that would be closer to ground truth. A better understanding of changes in grain size on area estimation will improve our...

  19. Shape-dependent guidance of active Janus particles by chemically patterned surfaces

    Science.gov (United States)

    Uspal, W. E.; Popescu, M. N.; Tasinkevych, M.; Dietrich, S.

    2018-01-01

    Self-phoretic chemically active Janus particles move by inducing—via non-equilibrium chemical reactions occurring on their surfaces—changes in the chemical composition of the solution in which they are immersed. This process leads to gradients in chemical composition along the surface of the particle, as well as along any nearby boundaries, including solid walls. Chemical gradients along a wall can give rise to chemi-osmosis, i.e., the gradients drive surface flows which, in turn, drive flow in the volume of the solution. This bulk flow couples back to the particle, and thus contributes to its self-motility. Since chemi-osmosis strongly depends on the molecular interactions between the diffusing molecular species and the wall, the response flow induced and experienced by a particle encodes information about any chemical patterning of the wall. Here, we extend previous studies on self-phoresis of a sphere near a chemically patterned wall to the case of particles with rod-like, elongated shape. We focus our analysis on the new phenomenology potentially emerging from the coupling—which is inoperative for a spherical shape—of the elongated particle to the strain rate tensor of the chemi-osmotic flow. Via detailed numerical calculations, we show that the dynamics of a rod-like particle exhibits a novel ‘edge-following’ steady state: the particle translates along the edge of a chemical step at a steady distance from the step and with a steady orientation. Moreover, within a certain range of system parameters, the edge-following state co-exists with a ‘docking’ state (the particle stops at the step, oriented perpendicular to the step edge), i.e., a bistable dynamics occurs. These findings are rationalized as a consequence of the competition between the fluid vorticity and the rate of strain by using analytical theory based on the point-particle approximation which captures quasi-quantitatively the dynamics of the system.

  20. Soil-dependent uptake of 137Cs by mushrooms: experimental study in the Chernobyl accident areas

    International Nuclear Information System (INIS)

    Kaduka, M.V.; Shutov, V.N.; Bruk, G.Ya.; Balonov, M.I.; Brown, J.E.; Strand, P.

    2006-01-01

    The influence of agrochemical properties of forest soils and growth conditions on 137 Cs aggregated transfer factors from soil to different species of forest mushrooms have been analysed. Statistically significant correlations between 137 Cs soil to mushroom aggregated transfer factors and agrochemical soil properties have been revealed. The experimental data show that 137 Cs aggregated transfer factors depend on the mushroom's trophic group, biological family, genus and species. They also strongly depend on forest soil properties and their values can be estimated with the use of multiple regression equations constructed from agrochemical soil parameters which most closely correlate with the 137 Cs transfer parameters for particular mushroom groups

  1. Impacts of urban land-surface forcing on ozone air quality in the Seoul metropolitan area

    Directory of Open Access Journals (Sweden)

    Y.-H. Ryu

    2013-02-01

    Full Text Available Modified local meteorology owing to heterogeneities in the urban–rural surface can affect urban air quality. In this study, the impacts of urban land-surface forcing on ozone air quality during a high ozone (O3 episode in the Seoul metropolitan area, South Korea, are investigated using a high-resolution chemical transport model (CMAQ. Under fair weather conditions, the temperature excess (urban heat island significantly modifies boundary layer characteristics/structures and local circulations. The modified boundary layer and local circulations result in an increase in O3 levels in the urban area of 16 ppb in the nighttime and 13 ppb in the daytime. Enhanced turbulence in the deep urban boundary layer dilutes pollutants such as NOx, and this contributes to the elevated O3 levels through the reduced O3 destruction by NO in the NOx-rich environment. The advection of O3 precursors over the mountains near Seoul by the prevailing valley-breeze circulation in the mid- to late morning results in the build-up of O3 over the mountains in conjunction with biogenic volatile organic compound (BVOC emissions there. As the prevailing local circulation in the afternoon changes to urban-breeze circulation, the O3-rich air masses over the mountains are advected over the urban area. The urban-breeze circulation exerts significant influences on not only the advection of O3 but also the chemical production of O3 under the circumstances in which both anthropogenic and biogenic (natural emissions play important roles in O3 formation. As the air masses that are characterized by low NOx and high BVOC levels and long OH chain length are advected over the urban area from the surroundings, the ozone production efficiency increases in the urban area. The relatively strong vertical mixing in the urban boundary layer embedded in the

  2. Water surface area and depth determine oviposition choice in Aedes albopictus (Diptera: Culicidae).

    Science.gov (United States)

    Reiskind, Michael H; Zarrabi, Ali A

    2012-01-01

    Oviposition choice is a well-studied aspect of the mosquito life cycle, and offers a potential avenue for species-specific surveillance and control. In container inhabiting mosquitoes, there has been a focus on how the components of the aquatic media determine choice, with little work on the physical characteristics of the containers themselves. We performed five experiments examining the effect of physical container parameters on oviposition choice by Aedes albopictus. We examined containers of three different surface areas (small, 496 cm2; medium, 863 cm2; and large, 1,938 cm2) at the same water depth and the same or different heights in a series of binary choice assays. We also examined different depths with the same surface area in clear containers (where the depth may be perceived by the darkness of the water) and in opaque containers, which appear uniformly dark at different depths. We found a significant preference for medium containers over large containers, whether the containers were different or the same heights, and a trend toward a preference for small containers over medium containers. There was a preference for deeper water regardless of whether containers were clear or opaque. These behaviors suggest mosquitoes take into account physical aspects of their habitats and their oviposition choices are consistent with minimizing the risk of habitat drying.

  3. Synthesis of silica aerogel monoliths with controlled specific surface areas and pore sizes

    Science.gov (United States)

    Gao, Bingying; Lu, Shaoxiang; Kalulu, Mulenga; Oderinde, Olayinka; Ren, Lili

    2017-07-01

    To replace traditional preparation methods of silica aerogels, a small-molecule 1,2-epoxypropane (PO) has been introduced into the preparation process instead of using ammonia as the cross-linking agent, thus generating a lightweight, high porosity, and large surface area silica aerogel monolithic. We put forward a simple solution route for the chemical synthesis of silica aerogels, which was characterized by scanning electron microscopy (SEM), TEM, XRD, FTIR, thermogravimetric analysis (TGA) and the Brunauer-Emmett-Teller (BET) method In this paper, the effect of the amount of PO on the microstructure of silica aerogels is discussed. The BET surface areas and pore sizes of the resulting silica aerogels can be freely adjusted by changing the amount of PO, which will be helpful in promoting the development of silica aerogels to fabricate other porous materials with similar requirements. We also adopted a new organic solvent sublimation drying (OSSD) method to replace traditional expensive and dangerous drying methods such as critical point drying and freeze drying. This simple approach is easy to operate and has good repeatability, which will further facilitate actual applications of silica aerogels.

  4. Porous boron nitride with a high surface area: hydrogen storage and water treatment.

    Science.gov (United States)

    Li, Jie; Lin, Jing; Xu, Xuewen; Zhang, Xinghua; Xue, Yanming; Mi, Jiao; Mo, Zhaojun; Fan, Ying; Hu, Long; Yang, Xiaojing; Zhang, Jun; Meng, Fanbin; Yuan, Songdong; Tang, Chengchun

    2013-04-19

    We report on the synthesis of high-quality microporous/mesoporous BN material via a facile two-step approach. An extremely high surface area of 1687 m(2) g(-1) and a large pore volume of 0.99 cm(3) g(-1) have been observed in the synthesized BN porous whiskers. The formation of the porous structure was attributed to the group elimination of organic species in a BN precursor, melamine diborate molecular crystal. This elimination method maintained the ordered pore structure and numerous structural defects. The features including high surface area, pore volume and structural defects make the BN whiskers highly suitable for hydrogen storage and wastewater treatment applications. We demonstrate excellent hydrogen uptake capacity of the BN whiskers with high weight adsorption up to 5.6% at room temperature and at the relatively low pressure of 3 MPa. Furthermore, the BN whiskers also exhibit excellent adsorption capacity of methyl orange and copper ions, with the maximum removal capacity of 298.3 and 373 mg g(-1) at 298 K, respectively.

  5. High-Surface-Area Nitrogen-Doped Reduced Graphene Oxide for Electric Double-Layer Capacitors.

    Science.gov (United States)

    Youn, Hee-Chang; Bak, Seong-Min; Kim, Myeong-Seong; Jaye, Cherno; Fischer, Daniel A; Lee, Chang-Wook; Yang, Xiao-Qing; Roh, Kwang Chul; Kim, Kwang-Bum

    2015-06-08

    A two-step method consisting of solid-state microwave irradiation and heat treatment under NH3 gas was used to prepare nitrogen-doped reduced graphene oxide (N-RGO) with a high specific surface area (1007 m(2)  g(-1) ), high electrical conductivity (1532 S m(-1) ), and low oxygen content (1.5 wt %) for electrical double-layer capacitor applications. The specific capacitance of N-RGO was 291 F g(-1) at a current density of 1 A g(-1) , and a capacitance of 261 F g(-1) was retained at 50 A g(-1) , which indicated a very good rate capability. N-RGO also showed excellent cycling stability and preserved 96 % of the initial specific capacitance after 100 000 cycles. Near-edge X-ray absorption fine-structure spectroscopy results provided evidenced for the recovery of π conjugation in the carbon networks with the removal of oxygenated groups and revealed chemical bonding of the nitrogen atoms in N-RGO. The good electrochemical performance of N-RGO is attributed to its high surface area, high electrical conductivity, and low oxygen content. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Particle size and surface area effects on the thin-pulse shock initiation of Diaminoazoxyfurazan (DAAF)

    Science.gov (United States)

    Burritt, Rosemary; Francois, Elizabeth; Windler, Gary; Chavez, David

    2017-06-01

    Diaminoazoxyfurazan (DAAF) has many of the safety characteristics of an insensitive high explosive (IHE): it is extremely insensitive to impact and friction and is comparable to triaminotrinitrobezene (TATB) in this way. Conversely, it demonstrates many performance characteristics of a Conventional High Explosive (CHE). DAAF has a small failure diameter of about 1.25 mm and can be sensitive to shock under the right conditions. Large particle sized DAAF will not initiate in a typical exploding foil initiator (EFI) configuration but smaller particle sizes will. Large particle sized DAAF, of 40 μm, was crash precipitated and ball milled into six distinct samples and pressed into pellets with a density of 1.60 g/cc (91% TMD). To investigate the effect of particle size and surface area on the direct initiation on DAAF multiple threshold tests were preformed on each sample of DAAF in different EFI configurations, which varied in flyer thickness and/or bridge size. Comparative tests were performed examining threshold voltage and correlated to Photon Doppler Velocimetry (PDV) results. The samples with larger particle sizes and surface area required more energy to initiate while the smaller particle sizes required less energy and could be initiated with smaller diameter flyers.

  7. Closure Report for Corrective Action Unit 417: Central Nevada Test Area Surface, Nevada

    International Nuclear Information System (INIS)

    Campbell, K.B.

    2001-11-01

    This Closure Report provides the documentation for closure of the Central Nevada Test Area (CNTA) surface Corrective Action Unit (CAU) 417. The CNTA is located in Hot Creek Valley in Nye County, Nevada, approximately 22.5 kilometers (14 miles) west of U.S. State Highway 6 near the Moores Station historical site, and approximately 137 kilometers (85 miles) northeast of Tonopah, Nevada. The CNTA consists of three separate land withdrawal areas commonly referred to as UC-1, UC-3, and UC-4, all of which are accessible to the public. A nuclear device for Project Faultless was detonated approximately 975 meters (3,200 feet) below ground surface on January 19, 1968, in emplacement boring UC-1 (Department of Energy, Nevada Operation Office [DOE/NV], 1997). CAU 417 consists of 34 Corrective Action Sites (CASs). Site closure was completed using a Nevada Department of Environmental Protection (NDEP) approved Corrective Action Plan (CAP) (DOE/NV, 2000) which was based on the recommendations presented in the NDEP-approved Corrective Action Decision Document (DOE/NV, 1999). Closure of CAU 417 was completed in two phases. Phase I field activities were completed with NDEP concurrence during 1999 as outlined in the Phase I Work Plan, Appendix A of the CAP (DOE/NV, 2000), and as summarized in Section 2.1.2 of this document

  8. Quantifying the effect of waterways and green areas on the surface temperature

    Directory of Open Access Journals (Sweden)

    Elis Dener Lima Alves

    2017-02-01

    Full Text Available The cooling effects of urban parks and green areas, which form the “Park Cool Island” (PCI can help decrease the surface temperature and mitigate the effects of urban heat islands (UHI. Therefore, the objective of this research was to know the temporal variability of PCI intensity, as well as analyze the factors that determines it and propose an equation to predict the PCI intensity in Iporá, Goiás State, Brazil. To this purpose, the PCI intensity values were obtained using the Landsat-8 satellite (band 10, and then correlated with the NDVI and the LAI, in which proposes equations through multiple linear regression to estimate the PCI intensity. The results indicated that: 1 the greater the distance of the natural area, greater the surface temperature; 2 there is a great seasonality in PCI, in which the intensity of PCI is much higher in the spring (or close to it; 3 the relationship between NDVI and LAI variables, showed good coefficients of determination; 4 the equations for the buffer of 200 and 500 m, had low RMSE with high coefficients of determination (r2 = 0.924 and r2 = 0.957 respectively.

  9. Ultrahigh surface area carbon from carbonated beverages: Combining self-templating process and in situ activation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Pengfei; Zhang, Zhiyong; Chen, Jihua; Dai, Sheng

    2015-11-01

    Ultrahigh surface area carbons (USACs, e.g., >2000 m2/g) are attracting tremendous attention due to their outstanding performance in energy-related applications. The state-of-art approaches to USACs involve templating or activation methods and all these techniques show certain drawbacks. In this work, a series of USACs with specific surface areas up to 3633 m2/g were prepared in two steps: hydrothermal carbonization (200 °C) of carbonated beverages (CBs) and further thermal treatment in nitrogen (600–1000 °C). The rich inner porosity is formed by a self-templated process during which acids and polyelectrolyte sodium salts in the beverage formulas make some contribution. This strategy covers various CBs such as Coca Cola®, Pepsi Cola®, Dr. Pepper®, and Fanta® and it enables an acceptable product yield (based on sugars), for example: 21 wt% for carbon (2940 m2/g) from Coca Cola®. Being potential electrode materials for supercapacitors, those carbon materials possessed a good specific capacitance (57.2–185.7 F g-1) even at a scan rate of 1000 mV s-1. Thus, a simple and efficient strategy to USACs has been presented.

  10. Surface area-burnoff correlation for the steam--graphite reaction

    International Nuclear Information System (INIS)

    Stark, W.A. Jr.; Malinauskas, A.P.

    1977-01-01

    The oxidation of core graphite by steam of air represents a problem area of significant concern in safety analyses for the high temperature gas cooled reactor (HTGR). Core and core-support graphite integrity and strength deteriorate with oxidation of the graphite, and oxidation furthermore could affect the rate of fission product release under upset conditions. Consequently, modeling of core response during steam or air ingress conditions requires an expression for the rate of graphite interaction with those impurities. The steam--graphite reaction in particular is a complex interaction of mass transport within the graphite with chemi-sorption and reaction on accessible surfaces; experimental results from graphite to graphite are highly variable, and the description of the reaction is not yet completely consistent. A simple etch pit model relating surface area to burnoff has been proposed and shown to provide reasonable correlation with experimental data obtained from steam oxidation studies of nuclear grade H-327 graphite. Unaccounted differences between theory and experiment arise at burnoffs exceeding 3 to 5 percent. The model, while not complete nor comprehensive, is consistent with experimental observations of graphite oxidation by O 2 (air), CO 2 , or H 2 O, and could have some utility in safety analysis

  11. Spherical Torus Plasma Interactions with Large-area Liquid Lithium Surfaces in CDX-U

    International Nuclear Information System (INIS)

    Kaita, R.; Majeski, R.; Boaz, M.; Efthimion, P.; Jones, B.; Hoffman, D.; Kugel, H.; Menard, J.; Munsat, T.; Post-Zwicker, A.; Soukhanovskii, V.; Spaleta, J.; Taylor, G.; Timberlake, J.; Woolley, R.; Zakharov, L.; Finkenthal, M.; Stutman, D.; Antar, G.; Doerner, R.; Luckhardt, S.; Maingi, R.; Maiorano, M.; Smith, S.

    2002-01-01

    The Current Drive Experiment-Upgrade (CDX-U) device at the Princeton Plasma Physics Laboratory (PPPL) is a spherical torus (ST) dedicated to the exploration of liquid lithium as a potential solution to reactor first-wall problems such as heat load and erosion, neutron damage and activation, and tritium inventory and breeding. Initial lithium limiter experiments were conducted with a toroidally-local liquid lithium rail limiter (L3) from the University of California at San Diego. Spectroscopic measurements showed a clear reduction of impurities in plasmas with the L3, compared to discharges with a boron carbide limiter. The evidence for a reduction in recycling was less apparent, however. This may be attributable to the relatively small area in contact with the plasma, and the presence of high-recycling surfaces elsewhere in the vacuum chamber. This conclusion was tested in subsequent experiments with a fully toroidal lithium limiter that was installed above the floor of the vacuum vessel. The new limiter covered over ten times the area of the L3 facing the plasma. Experiments with the toroidal lithium limiter have recently begun. This paper describes the conditioning required to prepare the lithium surface for plasma operations, and effect of the toroidal liquid lithium limiter on discharge performance

  12. Spherical Torus Plasma Interactions with Large-area Liquid Lithium Surfaces in CDX-U

    Energy Technology Data Exchange (ETDEWEB)

    R. Kaita; R. Majeski; M. Boaz; P. Efthimion; B. Jones; D. Hoffman; H. Kugel; J. Menard; T. Munsat; A. Post-Zwicker; V. Soukhanovskii; J. Spaleta; G. Taylor; J. Timberlake; R. Woolley; L. Zakharov; M. Finkenthal; D. Stutman; G. Antar; R. Doerner; S. Luckhardt; R. Maingi; M. Maiorano; S. Smith

    2002-01-18

    The Current Drive Experiment-Upgrade (CDX-U) device at the Princeton Plasma Physics Laboratory (PPPL) is a spherical torus (ST) dedicated to the exploration of liquid lithium as a potential solution to reactor first-wall problems such as heat load and erosion, neutron damage and activation, and tritium inventory and breeding. Initial lithium limiter experiments were conducted with a toroidally-local liquid lithium rail limiter (L3) from the University of California at San Diego. Spectroscopic measurements showed a clear reduction of impurities in plasmas with the L3, compared to discharges with a boron carbide limiter. The evidence for a reduction in recycling was less apparent, however. This may be attributable to the relatively small area in contact with the plasma, and the presence of high-recycling surfaces elsewhere in the vacuum chamber. This conclusion was tested in subsequent experiments with a fully toroidal lithium limiter that was installed above the floor of the vacuum vessel. The new limiter covered over ten times the area of the L3 facing the plasma. Experiments with the toroidal lithium limiter have recently begun. This paper describes the conditioning required to prepare the lithium surface for plasma operations, and effect of the toroidal liquid lithium limiter on discharge performance.

  13. Permeability surface area product analysis in malignant brain edema prediction - A pilot study.

    Science.gov (United States)

    Volny, O; Cimflova, P; Lee, T-Y; Menon, B K; d'Esterre, C D

    2017-05-15

    Using an extended CT perfusion acquisition (150s), we sought to determine the association between perfusion parameters and malignant edema after ischemic stroke. Patients (from prospective study PROVE-IT, NCT02184936) with terminal internal carotid artery±proximal middle cerebral occlusion were involved. CTA was assessed for clot location and status of leptomeningeal collaterals. The following CTP parameters were calculated within the ischemic territory and contralaterally: permeability surface area product (PS), cerebral blood flow (CBF) and cerebral blood volume (CBV). PS was calculated using the adiabatic approximation to the Johnson and Wilson model. Outcome was evaluated by midline shift and infarction volume on follow-up imaging. Of 200 patients enrolled, 7 patients (3.5%) had midline shift≥5mm (2 excluded for poor-quality scans). Five patients with midline shift and 5 matched controls were analysed. There was no significant difference in mean PS, CBF and CBV within the ischemic territory between the two groups. A CBV threshold of 1.7ml/100g had the highest AUC=0.72, 95% CI=0.54-0.90 for early midline shift prediction, sensitivity and specificity were 0.83 and 0.67 respectively. Our preliminary results did not show significant differences in permeability surface area analysis if analysed for complete ischemic region. CBV parameter had the highest accuracy and there was a trend for the mean PS values for midline shift prediction. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Experiment Study on Determination of Surface Area of Finegrained Soils by Mercury Intrusion Porosimetry

    Science.gov (United States)

    Yan, X. Q.; Zhou, C. Y.; Fang, Y. G.; Lin, L. S.

    2017-12-01

    The specific surface area (SSA) has a great influence on the physical and chemical properties of fine-grained soils. Determination of specific surface area is an important content for fine-grained soils micro-meso analysis and characteristic research. In this paper, mercury intrusion porosimetry (MIP) was adopted to determine the SSA of fine-grained soils including quartz, kaolinite, bentonite and natural Shenzhen soft clay. The test results show that the average values of SSA obtained by MIP are 0.78m2/g, 11.31m2/g, 57.28m2/g and 27.15m2/g respectively for very fine-grained quartz, kaolin, bentonite and natural Shenzhen soft clay, and that it is feasible to apply MIP to obtain the SSA of fine-grained soils through statistical analysis of 97 samples. Through discussion, it is necessary to consider the state of fine-grained soils such as pore ratio when the SSA of fine-grained soils is determined by MIP.

  15. Non-activated high surface area expanded graphite oxide for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Vermisoglou, E.C.; Giannakopoulou, T.; Romanos, G.E.; Boukos, N.; Giannouri, M. [Institute of Nanoscience and Nanotechnology “Demokritos”, 153 43 Ag. Paraskevi, Attikis (Greece); Lei, C.; Lekakou, C. [Division of Mechanical, Medical, and Aerospace Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom); Trapalis, C., E-mail: c.trapalis@inn.demokritos.gr [Institute of Nanoscience and Nanotechnology “Demokritos”, 153 43 Ag. Paraskevi, Attikis (Greece)

    2015-12-15

    Graphical abstract: - Highlights: • One-step exfoliation and reduction of graphite oxide via microwave irradiation. • Effect of pristine graphite (type, flake size) on the microwave expanded material. • Effect of pretreatment and oxidation cycles on the produced expanded material. • Expanded graphene materials with high BET surface areas (940 m{sup 2}/g–2490 m{sup 2}/g). • Non-activated graphene based materials suitable for supercapacitors. - Abstract: Microwave irradiation of graphite oxide constitutes a facile route toward production of reduced graphene oxide, since during this treatment both exfoliation and reduction of graphite oxide occurs. In this work, the effect of pristine graphite (type, size of flakes), pretreatment and oxidation cycles on the finally produced expanded material was examined. All the types of graphite that were tested afforded materials with high BET surface areas ranging from 940 m{sup 2}/g to 2490 m{sup 2}/g, without intervening an activation stage at elevated temperature. SEM and TEM images displayed exfoliated structures, where the flakes were significantly detached and curved. The quality of the reduced graphene oxide sheets was evidenced both by X-ray photoelectron spectroscopy and Raman spectroscopy. The electrode material capacitance was determined via electrochemical impedance spectroscopy and cyclic voltammetry. The materials with PEDOT binder had better performance (∼97 F/g) at low operation rates while those with PVDF binder performed better (∼20 F/g) at higher rates, opening up perspectives for their application in supercapacitors.

  16. Reduction Expansion Synthesis as Strategy to Control Nitrogen Doping Level and Surface Area in Graphene.

    Science.gov (United States)

    Canty, Russell; Gonzalez, Edwin; MacDonald, Caleb; Osswald, Sebastian; Zea, Hugo; Luhrs, Claudia C

    2015-10-16

    Graphene sheets doped with nitrogen were produced by the reduction-expansion (RES) method utilizing graphite oxide (GO) and urea as precursor materials. The simultaneous graphene generation and nitrogen insertion reactions are based on the fact that urea decomposes upon heating to release reducing gases. The volatile byproducts perform two primary functions: (i) promoting the reduction of the GO and (ii) providing the nitrogen to be inserted in situ as the graphene structure is created. Samples with diverse urea/GO mass ratios were treated at 800 °C in inert atmosphere to generate graphene with diverse microstructural characteristics and levels of nitrogen doping. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to study the microstructural features of the products. The effects of doping on the samples structure and surface area were studied by X-ray diffraction (XRD), Raman Spectroscopy, and Brunauer Emmet Teller (BET). The GO and urea decomposition-reduction process as well as nitrogen-doped graphene stability were studied by thermogravimetric analysis (TGA) coupled with mass spectroscopy (MS) analysis of the evolved gases. Results show that the proposed method offers a high level of control over the amount of nitrogen inserted in the graphene and may be used alternatively to control its surface area. To demonstrate the practical relevance of these findings, as-produced samples were used as electrodes in supercapacitor and battery devices and compared with conventional, thermally exfoliated graphene.

  17. Reduction Expansion Synthesis as Strategy to Control Nitrogen Doping Level and Surface Area in Graphene

    Directory of Open Access Journals (Sweden)

    Russell Canty

    2015-10-01

    Full Text Available Graphene sheets doped with nitrogen were produced by the reduction-expansion (RES method utilizing graphite oxide (GO and urea as precursor materials. The simultaneous graphene generation and nitrogen insertion reactions are based on the fact that urea decomposes upon heating to release reducing gases. The volatile byproducts perform two primary functions: (i promoting the reduction of the GO and (ii providing the nitrogen to be inserted in situ as the graphene structure is created. Samples with diverse urea/GO mass ratios were treated at 800 °C in inert atmosphere to generate graphene with diverse microstructural characteristics and levels of nitrogen doping. Scanning electron microscopy (SEM and transmission electron microscopy (TEM were used to study the microstructural features of the products. The effects of doping on the samples structure and surface area were studied by X-ray diffraction (XRD, Raman Spectroscopy, and Brunauer Emmet Teller (BET. The GO and urea decomposition-reduction process as well as nitrogen-doped graphene stability were studied by thermogravimetric analysis (TGA coupled with mass spectroscopy (MS analysis of the evolved gases. Results show that the proposed method offers a high level of control over the amount of nitrogen inserted in the graphene and may be used alternatively to control its surface area. To demonstrate the practical relevance of these findings, as-produced samples were used as electrodes in supercapacitor and battery devices and compared with conventional, thermally exfoliated graphene.

  18. Development of a GNSS Buoy for Monitoring Water Surface Elevations in Estuaries and Coastal Areas.

    Science.gov (United States)

    Lin, Yen-Pin; Huang, Ching-Jer; Chen, Sheng-Hsueh; Doong, Dong-Jiing; Kao, Chia Chuen

    2017-01-18

    In this work, a Global Navigation Satellite System (GNSS) buoy that utilizes a Virtual Base Station (VBS) combined with the Real-Time Kinematic (RTK) positioning technology was developed to monitor water surface elevations in estuaries and coastal areas. The GNSS buoy includes a buoy hull, a RTK GNSS receiver, data-transmission devices, a data logger, and General Purpose Radio Service (GPRS) modems for transmitting data to the desired land locations. Laboratory and field tests were conducted to test the capability of the buoy and verify the accuracy of the monitored water surface elevations. For the field tests, the GNSS buoy was deployed in the waters of Suao (northeastern part of Taiwan). Tide data obtained from the GNSS buoy were consistent with those obtained from the neighboring tide station. Significant wave heights, zero-crossing periods, and peak wave directions obtained from the GNSS buoy were generally consistent with those obtained from an accelerometer-tilt-compass (ATC) sensor. The field tests demonstrate that the developed GNSS buoy can be used to obtain accurate real-time tide and wave data in estuaries and coastal areas.

  19. Surface hydrophobic co-modification of hollow silica nanoparticles toward large-area transparent superhydrophobic coatings.

    Science.gov (United States)

    Gao, Liangjuan; He, Junhui

    2013-04-15

    The present paper reports a novel, simple, and efficient approach to fabricate transparent superhydrophobic coatings on glass substrates by spray-coating stearic acid (STA) and 1H,1H,2H,2H-perflurooctyltriethoxysilane (POTS) co-modified hollow silica nanoparticles (SPHSNs), the surfaces of which were hydrophobic. The surface wettability of coatings was dependent on the conditions of post-treatment: the water contact angle of coating increased and then leveled off with increase in either the drying temperature or the drying time. When the coating was treated at 150°C for 5h, the water contact angle was as high as 160° and the sliding angle was lower than 1°, reaching excellent superhydrophobicity. They remained 159° and ≤1°, respectively, even after 3months storage under indoor conditions (20°C, 20%RH), demonstrating the long time stability of coating superhydrophobicity. The coating was robust both to the impact of water droplets (297 cm/s) and to acidic (pH=1) and basic (pH=14) droplets. It showed good transparency in the visible-near infrared spectral range, and the maximum transmittance reached as high as 89%. Fourier transform infrared spectroscopy, transmission electron microscopy, differential scanning calorimetry, and thermogravimetric analysis were used to investigate the interactions among STA, POTS, and hollow silica nanoparticles (HSNs). Scanning electron microscopy and atomic force microscopy were used to observe and estimate the morphology and surface roughness of coatings. Optical properties were characterized by a UV-visible-near infrared spectrophotometer. Surface wettability was studied by a contact angle/interface system. The enhancement of hydrophobicity to superhydrophobicity by post-treatment was discussed based on the transition from the Wenzel state to the Cassie state. Copyright © 2013 Elsevier Inc. All rights reserved.

  20. Experimental Study on the Microstructure Evolution of Mixed Disposal Paste in Surface Subsidence Areas

    Directory of Open Access Journals (Sweden)

    Wei Sun

    2016-05-01

    Full Text Available The integrated disposal of surface subsidence pits and surface solid waste can be realized by backfilling a surface subsidence area with a paste made from the solid wastes of mines, such as tailings and waste rock. The microstructures of these wastes determine the macroscopic properties of a paste backfill. This paper presents an experimental study on the internal structure evolution of pasty fluid mixed with different waste rock concentrations (10%, 30%, and 50% and cement dosages (1% and 2% under damage. To this end, a real-time computed tomography (CT scan is conducted using medical CT and a small loading device. Results show that UCS (uniaxial compressive strength increases when the amount of cement increases. Given a constant amount of cement, UCS increases first and then decreases as waste rock content increases. UCS is maximized at 551 kPa when the waste rock content is 30%. The paste body is a typical medium used to investigate initial damage, which mainly consists of microholes, pores, and microcracks. The initial damages also exhibit a high degree of random inhomogeneity. After loading, cracks are initiated and expand gradually from the original damage location until the overall damages are generated. The mesostructure evolution model of the paste body is divided into six categories, and this mesostructure is reasonable when the waste rock content is 30%.

  1. Topographic Effects on the Surface Emissivity of a Mountainous Area Observed by a Spaceborne Microwave Radiometer

    Directory of Open Access Journals (Sweden)

    Frank S. Marzano

    2008-03-01

    Full Text Available A simulation study to understand the influence of topography on the surfaceemissivity observed by a satellite microwave radiometer is carried out. We analyze theeffects due to changes in observation angle, including the rotation of the polarization plane.A mountainous area in the Alps (Northern Italy is considered and the information on therelief extracted from a digital elevation model is exploited. The numerical simulation refersto a radiometric image, acquired by a conically-scanning radiometer similar to AMSR-E,i.e., flying at 705 km of altitude with an observation angle of 55°. To single out the impacton surface emissivity, scattering of the radiation due to the atmosphere or neighboringelevated surfaces is not considered. C and X bands, for which atmospheric effects arenegligible, and Ka band are analyzed. The results indicate that the changes in the localobservation angle tend to lower the apparent emissivity of a radiometric pixel with respectto the corresponding flat surface characteristics. The effect of the rotation of thepolarization plane enlarges (vertical polarization, or attenuates (horizontal polarizationthis decrease. By doing some simplifying assumptions for the radiometer antenna, theconclusion is that the microwave emissivity at vertical polarization is underestimated,whilst the opposite occurs for horizontal polarization, except for Ka band, for which bothunder- and overprediction may occur. A quantification of the differences with respect to aflat soil and an approximate evaluation of their impact on soil moisture retrieval areyielded.

  2. Synthetic microfluidic paper: high surface area and high porosity polymer micropillar arrays.

    Science.gov (United States)

    Hansson, Jonas; Yasuga, Hiroki; Haraldsson, Tommy; van der Wijngaart, Wouter

    2016-01-21

    We introduce Synthetic Microfluidic Paper, a novel porous material for microfluidic applications that consists of an OSTE polymer that is photostructured in a well-controlled geometry of slanted and interlocked micropillars. We demonstrate the distinct benefits of Synthetic Microfluidic Paper over other porous microfluidic materials, such as nitrocellulose, traditional paper and straight micropillar arrays: in contrast to straight micropillar arrays, the geometry of Synthetic Microfluidic Paper was miniaturized without suffering capillary collapse during manufacturing and fluidic operation, resulting in a six-fold increased internal surface area and a three-fold increased porous fraction. Compared to commercial nitrocellulose materials for capillary assays, Synthetic Microfluidic Paper shows a wider range of capillary pumping speed and four times lower device-to-device variation. Compared to the surfaces of the other porous microfluidic materials that are modified by adsorption, Synthetic Microfluidic Paper contains free thiol groups and has been shown to be suitable for covalent surface chemistry, demonstrated here for increasing the material hydrophilicity. These results illustrate the potential of Synthetic Microfluidic Paper as a porous microfluidic material with improved performance characteristics, especially for bioassay applications such as diagnostic tests.

  3. Diversity of Bacterial Communities of Fitness Center Surfaces in a U.S. Metropolitan Area

    Directory of Open Access Journals (Sweden)

    Nabanita Mukherjee

    2014-12-01

    Full Text Available Public fitness centers and exercise facilities have been implicated as possible sources for transmitting community-acquired bacterial infections. However, the overall diversity of the bacterial community residing on the surfaces in these indoor environments is still unknown. In this study, we investigated the overall bacterial ecology of selected fitness centers in a metropolitan area (Memphis, TN, USA utilizing culture-independent pyrosequencing of the 16S rRNA genes. Samples were collected from the skin-contact surfaces (e.g., exercise instruments, floor mats, handrails, etc. within fitness centers. Taxonomical composition revealed the abundance of Firmicutes phyla, followed by Proteobacter and Actinobacteria, with a total of 17 bacterial families and 25 bacterial genera. Most of these bacterial genera are of human and environmental origin (including, air, dust, soil, and water. Additionally, we found the presence of some pathogenic or potential pathogenic bacterial genera including Salmonella, Staphylococcus, Klebsiella, and Micrococcus. Staphylococcus was found to be the most prevalent genus. Presence of viable forms of these pathogens elevates risk of exposure of any susceptible individuals. Several factors (including personal hygiene, surface cleaning and disinfection schedules of the facilities may be the reasons for the rich bacterial diversity found in this study. The current finding underscores the need to increase public awareness on the importance of personal hygiene and sanitation for public gym users.

  4. Diversity of bacterial communities of fitness center surfaces in a U.S. metropolitan area.

    Science.gov (United States)

    Mukherjee, Nabanita; Dowd, Scot E; Wise, Andy; Kedia, Sapna; Vohra, Varun; Banerjee, Pratik

    2014-12-03

    Public fitness centers and exercise facilities have been implicated as possible sources for transmitting community-acquired bacterial infections. However, the overall diversity of the bacterial community residing on the surfaces in these indoor environments is still unknown. In this study, we investigated the overall bacterial ecology of selected fitness centers in a metropolitan area (Memphis, TN, USA) utilizing culture-independent pyrosequencing of the 16S rRNA genes. Samples were collected from the skin-contact surfaces (e.g., exercise instruments, floor mats, handrails, etc.) within fitness centers. Taxonomical composition revealed the abundance of Firmicutes phyla, followed by Proteobacter and Actinobacteria, with a total of 17 bacterial families and 25 bacterial genera. Most of these bacterial genera are of human and environmental origin (including, air, dust, soil, and water). Additionally, we found the presence of some pathogenic or potential pathogenic bacterial genera including Salmonella, Staphylococcus, Klebsiella, and Micrococcus. Staphylococcus was found to be the most prevalent genus. Presence of viable forms of these pathogens elevates risk of exposure of any susceptible individuals. Several factors (including personal hygiene, surface cleaning and disinfection schedules of the facilities) may be the reasons for the rich bacterial diversity found in this study. The current finding underscores the need to increase public awareness on the importance of personal hygiene and sanitation for public gym users.

  5. Myocardial twitch duration and the dependence of oxygen consumption on pressure-volume area: experiments and modelling.

    Science.gov (United States)

    Han, J-C; Tran, K; Taberner, A J; Nickerson, D P; Kirton, R S; Nielsen, P M F; Ward, M-L; Nash, M P; Crampin, E J; Loiselle, D S

    2012-09-15

    We tested the proposition that linear length dependence of twitch duration underlies the well-characterised linear dependence of oxygen consumption (V(O(2)) ) on pressure–volume area (PVA) in the heart. By way of experimental simplification, we reduced the problem from three dimensions to one by substituting cardiac trabeculae for the classically investigated whole-heart. This allowed adoption of stress–length area (SLA) as a surrogate for PVA, and heat as a proxy for V(O(2)) . Heat and stress (force per cross-sectional area), at a range of muscle lengths and at both 1 mM and 2 mM [Ca(2+)](o), were recorded from continuously superfused rat right-ventricular trabeculae undergoing fixed-end contractions. The heat–SLA relations of trabeculae (reported here, for the first time) are linear. Twitch duration increases monotonically (but not strictly linearly) with muscle length. We probed the cellular mechanisms of this phenomenon by determining: (i) the length dependence of the duration of the Ca(2+) transient, (ii) the length dependence of the rate of force redevelopment following a length impulse (an index of Ca(2+) binding to troponin-C), (iii) the effect on the simulated time course of the twitch of progressive deletion of length and Ca(2+)-dependent mechanisms of crossbridge cooperativity, using a detailed mathematical model of the crossbridge cycle, and (iv) the conditions required to achieve these multiple length dependencies, using a greatly simplified model of twitch mechano-energetics. From the results of these four independent investigations, we infer that the linearity of the heat–SLA relation (and, by analogy, the V(O(2))–PVA relation) is remarkably robust in the face of departures from linearity of length-dependent twitch duration.

  6. Myocardial twitch duration and the dependence of oxygen consumption on pressure–volume area: experiments and modelling

    Science.gov (United States)

    Han, J-C; Tran, K; Taberner, A J; Nickerson, D P; Kirton, R S; Nielsen, P M F; Ward, M-L; Nash, M P; Crampin, E J; Loiselle, D S

    2012-01-01

    We tested the proposition that linear length dependence of twitch duration underlies the well-characterised linear dependence of oxygen consumption () on pressure–volume area (PVA) in the heart. By way of experimental simplification, we reduced the problem from three dimensions to one by substituting cardiac trabeculae for the classically investigated whole-heart. This allowed adoption of stress–length area (SLA) as a surrogate for PVA, and heat as a proxy for . Heat and stress (force per cross-sectional area), at a range of muscle lengths and at both 1 mm and 2 mm[Ca2+]o, were recorded from continuously superfused rat right-ventricular trabeculae undergoing fixed-end contractions. The heat–SLA relations of trabeculae (reported here, for the first time) are linear. Twitch duration increases monotonically (but not strictly linearly) with muscle length. We probed the cellular mechanisms of this phenomenon by determining: (i) the length dependence of the duration of the Ca2+ transient, (ii) the length dependence of the rate of force redevelopment following a length impulse (an index of Ca2+ binding to troponin-C), (iii) the effect on the simulated time course of the twitch of progressive deletion of length- and Ca2+-dependent mechanisms of crossbridge cooperativity, using a detailed mathematical model of the crossbridge cycle, and (iv) the conditions required to achieve these multiple length dependencies, using a greatly simplified model of twitch mechano-energetics. From the results of these four independent investigations, we infer that the linearity of the heat–SLA relation (and, by analogy, the –PVA relation) is remarkably robust in the face of departures from linearity of length-dependent twitch duration. PMID:22570375

  7. Benchmarking sensitivity of biophysical processes to leaf area changes in land surface models

    Science.gov (United States)

    Forzieri, Giovanni; Duveiller, Gregory; Georgievski, Goran; Li, Wei; Robestson, Eddy; Kautz, Markus; Lawrence, Peter; Ciais, Philippe; Pongratz, Julia; Sitch, Stephen; Wiltshire, Andy; Arneth, Almut; Cescatti, Alessandro

    2017-04-01

    Land surface models (LSM) are widely applied as supporting tools for policy-relevant assessment of climate change and its impact on terrestrial ecosystems, yet knowledge of their performance skills in representing the sensitivity of biophysical processes to changes in vegetation density is still limited. This is particularly relevant in light of the substantial impacts on regional climate associated with the changes in leaf area index (LAI) following the observed global greening. Benchmarking LSMs on the sensitivity of the simulated processes to vegetation density is essential to reduce their uncertainty and improve the representation of these effects. Here we present a novel benchmark system to assess model capacity in reproducing land surface-atmosphere energy exchanges modulated by vegetation density. Through a collaborative effort of different modeling groups, a consistent set of land surface energy fluxes and LAI dynamics has been generated from multiple LSMs, including JSBACH, JULES, ORCHIDEE, CLM4.5 and LPJ-GUESS. Relationships of interannual variations of modeled surface fluxes to LAI changes have been analyzed at global scale across different climatological gradients and compared with satellite-based products. A set of scoring metrics has been used to assess the overall model performances and a detailed analysis in the climate space has been provided to diagnose possible model errors associated to background conditions. Results have enabled us to identify model-specific strengths and deficiencies. An overall best performing model does not emerge from the analyses. However, the comparison with other models that work better under certain metrics and conditions indicates that improvements are expected to be potentially achievable. A general amplification of the biophysical processes mediated by vegetation is found across the different land surface schemes. Grasslands are characterized by an underestimated year-to-year variability of LAI in cold climates

  8. Satellite Observed Variability in Antarctic and Arctic Surface Temperatures and Their Correlation to Open Water Areas

    Science.gov (United States)

    Comiso, Josefino C.; Zukor, Dorothy (Technical Monitor)

    2000-01-01

    Recent studies using meterological station data have indicated that global surface air temperature has been increasing at a rate of 0.05 K/decade. Using the same set of data but for stations in the Antarctic and Arctic regions (>50 N) only, the increases in temperature were 0.08, and 0.22 K/decade, when record lengths of 100 and 50 years, respectively, were used. To gain insights into the increasing rate of warming, satellite infrared and passive microwave observations over the Arctic region during the last 20 years were processed and analyzed. The results show that during this period, the ice extent in the Antarctic has been increasing at the rate of 1.2% per decade while the surface temperature has been decreasing at about 0.08 K per decade. Conversely, in the Northern Hemisphere, the ice extent has been decreasing at a rate of 2.8% per decade, while the surface temperatures have been increasing at the rate of 0.38 K per decade. In the Antarctic, it is surprising that there is a short term trend of cooling during a global period of warming. Very large anomalies in open water areas in the Arctic were observed especially in the western region, that includes the Beaufort Sea, where the observed open water area was about 1x10(exp 6) sq km, about twice the average for the region, during the summer of 1998. In the eastern region, that includes the Laptev Sea, the area of open water was also abnormally large in the summer of 1995. Note that globally, the warmest and second warmest years in this century, were 1998 and 1995, respectively. The data, however, show large spatial variability with the open water area distribution showing a cyclic periodicity of about ten years, which is akin to the North Atlantic and Arctic Oscillations. This was observed in both western and eastern regions but with the phase of one lagging the other by about two years. This makes it difficult to interpret what the trends really mean. But although the record length of satellite data is still

  9. Changes of Surface Electric Potential of Bones Depending on Their Age

    OpenAIRE

    Freimanis, E; Dehtjars, J; Vendiņa, V

    2014-01-01

    The aim of this research was to determine how surface electric potential of bones changes with their age and how it correlates with mechanical properties of bones. Surface electric potential was measured in 6 cross-sectional zones of the tibia. Changes of bones surface electric potential with age were determined and correlations between surface electric potential and mechanical properties were derived.

  10. The relationship between epicuticular long-chained hydrocarbons and surface area - volume ratios in insects (Diptera, Hymenoptera, Lepidoptera).

    Science.gov (United States)

    Brückner, Adrian; Heethoff, Michael; Blüthgen, Nico

    2017-01-01

    Long-chain cuticular hydrocarbons (CHCs) are common components of the epicuticle of terrestrial arthropods. CHC serve as a protective barrier against environmental influences but also act as semiochemicals in animal communication. Regarding the latter aspect, species- or intra-functional group specific CHCs composition and variation are relatively well studied. However, comparative knowledge about the relationship of CHC quantity and their relation to surface area-volume ratios in the context of water loss and protection is fragmentary. Hence, we aim to study the taxon-specific relationship of the CHC amount and surface-area to volume ratio related to their functional role (e.g. in water loss). We focused on flower visiting insects and analyzed the CHC amounts of three insect orders (Hymenoptera, Lepidoptera and Diptera) using gas chromatography-mass spectrometry (GC-MS). We included 113 species from two grassland plots, quantified their CHCs, and measured their body mass and surface area. We found differences in the surface area, CHCs per body mass and the CHC density (= amount of CHCs per surface area) across the three insect taxa. Especially the Hymenoptera had a higher CHC density compared to Diptera and Lepidoptera. CHC density could be explained by surface area-volume ratios in Hymenoptera but not in Diptera and Lepidoptera. Unexpectedly, CHC density decreased with increasing surface area-volume ratios.

  11. In Situ Aerosol Profile Measurements and Comparisons with SAGE 3 Aerosol Extinction and Surface Area Profiles at 68 deg North

    Science.gov (United States)

    2005-01-01

    Under funding from this proposal three in situ profile measurements of stratospheric sulfate aerosol and ozone were completed from balloon-borne platforms. The measured quantities are aerosol size resolved number concentration and ozone. The one derived product is aerosol size distribution, from which aerosol moments, such as surface area, volume, and extinction can be calculated for comparison with SAGE III measurements and SAGE III derived products, such as surface area. The analysis of these profiles and comparison with SAGE III extinction measurements and SAGE III derived surface areas are provided in Yongxiao (2005), which comprised the research thesis component of Mr. Jian Yongxiao's M.S. degree in Atmospheric Science at the University of Wyoming. In addition analysis continues on using principal component analysis (PCA) to derive aerosol surface area from the 9 wavelength extinction measurements available from SAGE III. Ths paper will present PCA components to calculate surface area from SAGE III measurements and compare these derived surface areas with those available directly from in situ size distribution measurements, as well as surface areas which would be derived from PCA and Thomason's algorithm applied to the four wavelength SAGE II extinction measurements.

  12. Theoretical research of some parameters of contact area of wheel cutting surface and workpiece at flat face grinding with preliminary inclination of spindle axis

    Directory of Open Access Journals (Sweden)

    I. N. Pyzhov

    2016-12-01

    Full Text Available Theoretical researches that have made it possible to obtain the analytical dependences connecting the parameters of contact area of wheel cutting surface such as length, width, arc length, form deviation of flat surface and workpiece under conditions of flat face grinding with preliminary inclination of spindle axis have been carried out. The paper shows the role of the angle of preliminary inclination of spindle axis, grinding depth and the wheel diameter in the grinding process. It allows correctly determining the value of the transverse feed (in multiple-pass processing which, as it is known, should be conformed to the value of the contact width of the wheel cutting surface and workpiece. It guarantees that on the machined surface there will be no areas unaffected by the wheel. In case of through grinding the obtained theoretical dependences help to determine the processing conditions, taking into account the allowable values of form deviation of flat surface. All this makes it possible to improve the process of flat face grinding and thereby expand its technological capabilities.

  13. Path dependence of fracture mechanics integrals on the integration area of characteristic integrals

    International Nuclear Information System (INIS)

    Roche, Roland.

    1975-11-01

    The necessary and sufficient conditions for characteristic integrals of fracture mechanics to be independent of area (or integration path), without making any assumptions concerning the behavior of the material are defined. The principle of the method involves comparing the spatial variation in energy density received with that which would result from a spatial variation in strain alone. This introduces a defect vector at each point of the solid. The resultants of the total defect vectors situated within an area are the characteristic integrals of this area. The condition governing independence in a region requires that the defect vector be null at any point. This condition in set under different forms which actually state that the energy density per unit volume received must have the same form of variation in space as in time [fr

  14. New model for estimating the relationship between surface area and volume in the human body using skeletal remains.

    Science.gov (United States)

    Kasabova, Boryana E; Holliday, Trenton W

    2015-04-01

    A new model for estimating human body surface area and body volume/mass from standard skeletal metrics is presented. This model is then tested against both 1) "independently estimated" body surface areas and "independently estimated" body volume/mass (both derived from anthropometric data) and 2) the cylindrical model of Ruff. The model is found to be more accurate in estimating both body surface area and body volume/mass than the cylindrical model, but it is more accurate in estimating body surface area than it is for estimating body volume/mass (as reflected by the standard error of the estimate when "independently estimated" surface area or volume/mass is regressed on estimates derived from the present model). Two practical applications of the model are tested. In the first test, the relative contribution of the limbs versus the trunk to the body's volume and surface area is compared between "heat-adapted" and "cold-adapted" populations. As expected, the "cold-adapted" group has significantly more of its body surface area and volume in its trunk than does the "heat-adapted" group. In the second test, we evaluate the effect of variation in bi-iliac breadth, elongated or foreshortened limbs, and differences in crural index on the body's surface area to volume ratio (SA:V). Results indicate that the effects of bi-iliac breadth on SA:V are substantial, while those of limb lengths and (especially) the crural index are minor, which suggests that factors other than surface area relative to volume are driving morphological variation and ecogeographical patterning in limb prorportions. © 2014 Wiley Periodicals, Inc.

  15. Woody vegetation and succession on the Fonde surface mine demonstration area, Bell County, Kentucky

    International Nuclear Information System (INIS)

    Wade, G.L.; Thompson, R.L.

    1999-01-01

    The long term impact of surface mining on vegetation and plant succession has always been of concern to environmentalists and residents of Appalachia. The Fonde Surface Mine Demonstration Area is a 7.3-ha, NE-NW-aspect contour coal mine at an elevation of 562 m. It was reclaimed in 1965 to show state-of-the-art surface mine reclamation techniques consistent with then-current law and regulations after coal mining in 1959 and 1963. The mine spoils were lightly graded to control erosion and crates a bench with water control and two sediment ponds. Soil pH ranged from 2.8 to 5.9. About 80 percent of the mine was planted with 18 tree and shrub species including plantations of mixed pine, mixed hardwoods, black locust, and shrubs for wildlife. In a complete floristic inventory conducted 25 years later, the authors found the woody flora consisted of 34 families, 53 genera, and 70 species including 7 exotics. This inventory of the Fonde mine shows that a diverse forest vegetation can be reestablished after extreme disturbances in Appalachia. Black locust, yellow poplar, and Virginia pine reproduction varied significantly among plantation types. Canopy tree species significantly affected ground layer cover, total species richness, number of tree seedling species, and total number of tree seedlings present. Mine soil type affected ground layer percent cover and total species richness. Pre-SMCRA (Surface Mining Control and Reclamation Act of 1977) reclaimed and inventoried mines can be used to evaluate biodiversity on post-SMCRA mines

  16. Effects of the Affordable Care Act's Dependent Coverage Mandate on Private Health Insurance Coverage in Urban and Rural Areas.

    Science.gov (United States)

    Look, Kevin A; Kim, Nam Hyo; Arora, Prachi

    2017-01-01

    To evaluate the impact of the Affordable Care Act's (ACA) dependent coverage mandate on insurance coverage among young adults in metropolitan and nonmetropolitan areas. A cross-sectional analysis was conducted using data from 2006-2009 and 2011 waves of the Medical Expenditure Panel Survey. A difference-in-difference analysis was used to compare changes in full-year private health insurance coverage among young adults aged 19-25 years with an older cohort aged 27-34 years. Separate regressions were estimated for individuals in metropolitan and nonmetropolitan areas and were tested for a differential impact by area of residence. Full-year private health insurance coverage significantly increased by 9.2 percentage points for young adults compared to the older cohort after the ACA mandate (P = .00). When stratifying the regression model by residence area, insurance coverage among young adults significantly increased by 9.0 percentage points in metropolitan areas (P = .00) and 10.1 percentage points in nonmetropolitan areas (P = .03). These changes were not significantly different from each other (P = .82), which suggests the ACA mandate's effects were not statistically different by area of residence. Although young adults in metropolitan and nonmetropolitan areas experienced increased access to private health insurance following the ACA's dependent coverage mandate, it did not appear to directly impact rural-urban disparities in health insurance coverage. Despite residents in both areas gaining insurance coverage, over one-third of young adults still lacked access to full-year health insurance coverage. © 2016 National Rural Health Association.

  17. Cell surface area and membrane folding in glioblastoma cell lines differing in PTEN and p53 status.

    Directory of Open Access Journals (Sweden)

    Simon Memmel

    Full Text Available Glioblastoma multiforme (GBM is characterized by rapid growth, invasion and resistance to chemo-/radiotherapy. The complex cell surface morphology with abundant membrane folds, microvilli, filopodia and other membrane extensions is believed to contribute to the highly invasive behavior and therapy resistance of GBM cells. The present study addresses the mechanisms leading to the excessive cell membrane area in five GBM lines differing in mutational status for PTEN and p53. In addition to scanning electron microscopy (SEM, the membrane area and folding were quantified by dielectric measurements of membrane capacitance using the single-cell electrorotation (ROT technique. The osmotic stability and volume regulation of GBM cells were analyzed by video microscopy. The expression of PTEN, p53, mTOR and several other marker proteins involved in cell growth and membrane synthesis were examined by Western blotting. The combined SEM, ROT and osmotic data provided independent lines of evidence for a large variability in membrane area and folding among tested GBM lines. Thus, DK-MG cells (wild type p53 and wild type PTEN exhibited the lowest degree of membrane folding, probed by the area-specific capacitance C m = 1.9 µF/cm(2. In contrast, cell lines carrying mutations in both p53 and PTEN (U373-MG and SNB19 showed the highest C m values of 3.7-4.0 µF/cm(2, which corroborate well with their heavily villated cell surface revealed by SEM. Since PTEN and p53 are well-known inhibitors of mTOR, the increased membrane area/folding in mutant GBM lines may be related to the enhanced protein and lipid synthesis due to a deregulation of the mTOR-dependent downstream signaling pathway. Given that membrane folds and extensions are implicated in tumor cell motility and metastasis, the dielectric approach presented here provides a rapid and simple tool for screening the biophysical cell properties in studies on targeting chemo- or radiotherapeutically the

  18. Multivariate Analyses of Heavy Metals in Surface Soil Around an Organized Industrial Area in Eskisehir, Turkey.

    Science.gov (United States)

    Malkoc, S; Yazici, B

    2017-02-01

    A total of 50 surface industrial area soil in Eskisehir, Turkey were collected and the concentrations of As, Cr, Cd, Co, Cu, Ni, Pb, Zn, Fe and Mg, at 11.34, 95.8, 1.37, 15.28, 33.06, 143.65, 14.34, 78.79 mg/kg, 188.80% and 78.70%, respectively. The EF values for As, Cu, Pb and Zn at a number of sampling sites were found to be the highest among metals. Igeo-index results show that the study area is moderately polluted with respect to As, Cd, Ni. According to guideline values of Turkey Environmental Quality Standard for Soils, there is no problem for Pb, but the Cd values are fairly high. However, Cr, Cu, Ni and Zn values mostly exceed the limits. Cluster analyses suggested that soil the contaminator values are homogenous in those sub classes. The prevention and remediation of the heavy metal soil pollution should focus on these high-risk areas in the future.

  19. Relationship between the Physical Properties and Surface Area of Cellulose Derived from Adsorbates of Various Molecular Sizes.

    Science.gov (United States)

    Ougiya, H; Hioki, N; Watanabe, K; Morinaga, Y; Yoshinaga, F; Samejima, M

    1998-01-01

    An aqueous suspension of bacterial cellulose (BC) has such physical properties as higher viscosity, emulsion-stabilizing effect and filler retention than cellulose of other origins. The specific surface areas of BC, microfibrillated cellulose and wood pulp were evaluated by determining the maximum amounts of adsorption of Congo red, cellobiose dehydrogenase (CDH) and xyloglucan. There was a positive linear correlation between the above-mentioned physical properties of each cellulose sample and the specific surface area derived from the maximum amount of CDH adsorbed. The highest physical property values for BC result from the largest external surface area of the fibrils of BC to which CDH was adsorbed.

  20. Human area MT+ shows load-dependent activation during working memory maintenance with continuously morphing stimulation.

    Science.gov (United States)

    Galashan, Daniela; Fehr, Thorsten; Kreiter, Andreas K; Herrmann, Manfred

    2014-07-11

    Initially, human area MT+ was considered a visual area solely processing motion information but further research has shown that it is also involved in various different cognitive operations, such as working memory tasks requiring motion-related information to be maintained or cognitive tasks with implied or expected motion.In the present fMRI study in humans, we focused on MT+ modulation during working memory maintenance using a dynamic shape-tracking working memory task with no motion-related working memory content. Working memory load was systematically varied using complex and simple stimulus material and parametrically increasing retention periods. Activation patterns for the difference between retention of complex and simple memorized stimuli were examined in order to preclude that the reported effects are caused by differences in retrieval. Conjunction analysis over all delay durations for the maintenance of complex versus simple stimuli demonstrated a wide-spread activation pattern. Percent signal change (PSC) in area MT+ revealed a pattern with higher values for the maintenance of complex shapes compared to the retention of a simple circle and with higher values for increasing delay durations. The present data extend previous knowledge by demonstrating that visual area MT+ presents a brain activity pattern usually found in brain regions that are actively involved in working memory maintenance.