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Sample records for surface layer esl

  1. Endothelial surface layer degradation by chronic hyaluronidase infusion induces proteinuria in apolipoprotein e-deficient mice

    NARCIS (Netherlands)

    Meuwese, Marijn C.; Broekhuizen, Lysette N.; Kuikhoven, Mayella; Heeneman, Sylvia; Lutgens, Esther; Gijbels, Marion J. J.; Nieuwdorp, Max; Peutz, Carine J.; Stroes, Erik S. G.; Vink, Hans; van den Berg, Bernard M.

    2010-01-01

    Functional studies show that disruption of endothelial surface layer (ESL) is accompanied by enhanced sensitivity of the vasculature towards atherogenic stimuli. However, relevance of ESL disruption as causal mechanism for vascular dysfunction remains to be demonstrated. We examined if loss of ESL

  2. Glomerular endothelial surface layer acts as a barrier against albumin filtration.

    Science.gov (United States)

    Dane, Martijn J C; van den Berg, Bernard M; Avramut, M Cristina; Faas, Frank G A; van der Vlag, Johan; Rops, Angelique L W M M; Ravelli, Raimond B G; Koster, Bram J; van Zonneveld, Anton Jan; Vink, Hans; Rabelink, Ton J

    2013-05-01

    Glomerular endothelium is highly fenestrated, and its contribution to glomerular barrier function is the subject of debate. In recent years, a polysaccharide-rich endothelial surface layer (ESL) has been postulated to act as a filtration barrier for large molecules, such as albumin. To test this hypothesis, we disturbed the ESL in C57Bl/6 mice using long-term hyaluronidase infusion for 4 weeks and monitored albumin passage using immunolabeling and correlative light-electron microscopy that allows for complete and integral assessment of glomerular albumin passage. ESL ultrastructure was visualized by transmission electron microscopy using cupromeronic blue and by localization of ESL binding lectins using confocal microscopy. We demonstrate that glomerular fenestrae are filled with dense negatively charged polysaccharide structures that are largely removed in the presence of circulating hyaluronidase, leaving the polysaccharide surfaces of other glomerular cells intact. Both retention of native ferritin [corrected] in the glomerular basement membrane and systemic blood pressure were unaltered. Enzyme treatment, however, induced albumin passage across the endothelium in 90% of glomeruli, whereas this could not be observed in controls. Yet, there was no net albuminuria due to binding and uptake of filtered albumin by the podocytes and parietal epithelium. ESL structure and function completely recovered within 4 weeks on cessation of hyaluronidase infusion. Thus, the polyanionic ESL component, hyaluronan, is a key component of the glomerular endothelial protein permeability barrier. Copyright © 2013 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  3. Glomerular endothelial surface layer acts as a barrier against albumin filtration

    NARCIS (Netherlands)

    Dane, M.J.; Berg, B.M. van den; Avramut, M.C.; Faas, F.G.; Vlag, J. van der; Rops, A.L.; Ravelli, R.B.; Koster, B.J.; Zonneveld, A.J. van; Vink, H.; Rabelink, T.J.

    2013-01-01

    Glomerular endothelium is highly fenestrated, and its contribution to glomerular barrier function is the subject of debate. In recent years, a polysaccharide-rich endothelial surface layer (ESL) has been postulated to act as a filtration barrier for large molecules, such as albumin. To test this

  4. Charge modification of the endothelial surface layer modulates the permeability barrier of isolated rat mesenteric small arteries

    NARCIS (Netherlands)

    van Haaren, Paul M. A.; VanBavel, Ed; Vink, Hans; Spaan, Jos A. E.

    2005-01-01

    We hypothesized that modulation of the effective charge density of the endothelial surface layer ( ESL) results in altered arterial barrier properties to transport of anionic solutes. Rat mesenteric small arteries ( diameter similar to 190 mu m) were isolated, cannulated, perfused, and superfused

  5. Endothelial surface layer degradation by chronic hyaluronidase infusion induces proteinuria in apolipoprotein E-deficient mice.

    Directory of Open Access Journals (Sweden)

    Marijn C Meuwese

    Full Text Available OBJECTIVE: Functional studies show that disruption of endothelial surface layer (ESL is accompanied by enhanced sensitivity of the vasculature towards atherogenic stimuli. However, relevance of ESL disruption as causal mechanism for vascular dysfunction remains to be demonstrated. We examined if loss of ESL through enzymatic degradation would affect vascular barrier properties in an atherogenic model. METHODS: Eight week old male apolipoprotein E deficient mice on Western-type diet for 10 weeks received continuous active or heat-inactivated hyaluronidase (10 U/hr, i.v. through an osmotic minipump during 4 weeks. Blood chemistry and anatomic changes in both macrovasculature and kidneys were examined. RESULTS: Infusion with active hyaluronidase resulted in decreased ESL (0.32±0.22 mL and plasma volume (1.03±0.18 mL compared to inactivated hyaluronidase (0.52±0.29 mL and 1.28±0.08 mL, p<0.05 respectively.Active hyaluronidase increased proteinuria compared to inactive hyaluronidase (0.27±0.02 vs. 0.15±0.01 µg/µg protein/creatinin, p<0.05 without changes in glomerular morphology or development of tubulo-interstitial inflammation. Atherosclerotic lesions in the aortic branches showed increased matrix production (collagen, 32±5 vs. 18±3%; glycosaminoglycans, 11±5 vs. 0.1±0.01%, active vs. inactive hyaluronidase, p<0.05. CONCLUSION: ESL degradation in apoE deficient mice contributes to reduced increased urinary protein excretion without significant changes in renal morphology. Second, the induction of compositional changes in atherogenic plaques by hyaluronidase point towards increased plaque vulnerability. These findings support further efforts to evaluate whether ESL restoration is a valuable target to prevent (micro vascular disease progression.

  6. Nanomechanics and sodium permeability of endothelial surface layer modulated by hawthorn extract WS 1442.

    Directory of Open Access Journals (Sweden)

    Wladimir Peters

    Full Text Available The endothelial glycocalyx (eGC plays a pivotal role in the physiology of the vasculature. By binding plasma proteins, the eGC forms the endothelial surface layer (ESL which acts as an interface between bloodstream and endothelial cell surface. The functions of the eGC include mechanosensing of blood flow induced shear stress and thus flow dependent vasodilation. There are indications that levels of plasma sodium concentrations in the upper range of normal and beyond impair flow dependent regulation of blood pressure and may therefore increase the risk for hypertension. Substances, therefore, that prevent sodium induced endothelial dysfunction may be attractive for the treatment of cardiovascular disease. By means of combined atomic force-epifluorescence microscopy we studied the impact of the hawthorn (Crataegus spp. extract WS 1442, a herbal therapeutic with unknown mechanism of action, on the mechanics of the ESL of ex vivo murine aortae. Furthermore, we measured the impact of WS 1442 on the sodium permeability of endothelial EA.hy 926 cell monolayer. The data show that (i the ESL contributes by about 11% to the total endothelial barrier resistance for sodium and (ii WS 1442 strengthens the ESL resistance for sodium up to about 45%. This mechanism may explain some of the vasoprotective actions of this herbal therapeutic.

  7. Single-layer model for surface roughness.

    Science.gov (United States)

    Carniglia, C K; Jensen, D G

    2002-06-01

    Random roughness of an optical surface reduces its specular reflectance and transmittance by the scattering of light. The reduction in reflectance can be modeled by a homogeneous layer on the surface if the refractive index of the layer is intermediate to the indices of the media on either side of the surface. Such a layer predicts an increase in the transmittance of the surface and therefore does not provide a valid model for the effects of scatter on the transmittance. Adding a small amount of absorption to the layer provides a model that predicts a reduction in both reflectance and transmittance. The absorbing layer model agrees with the predictions of a scalar scattering theory for a layer with a thickness that is twice the rms roughness of the surface. The extinction coefficient k for the layer is proportional to the thickness of the layer.

  8. Modifing the Surface Layers of Mechanical Components

    Directory of Open Access Journals (Sweden)

    K. Slanec

    2003-01-01

    Full Text Available This paper deals with the creation of thin surface layers prepared by the Plasma Assisted Chemical Vapour Deposition Method (PACVD. Polished sample surfaces made of tool steel were used. An investigation of the dependence of layer thickness on process duration was carried out. The structure of the original surface and the structure of the coated surface were evaluated and compared. The microhardness of the surface areas was also measured.

  9. Model castings with composite surface layer - application

    Directory of Open Access Journals (Sweden)

    J. Szajnar

    2008-10-01

    Full Text Available The paper presents a method of usable properties of surface layers improvement of cast carbon steel 200–450, by put directly in foundingprocess a composite surface layer on the basis of Fe-Cr-C alloy. Technology of composite surface layer guarantee mainly increase inhardness and aberasive wear resistance of cast steel castings on machine elements. This technology can be competition for generallyapplied welding technology (surfacing by welding and thermal spraying. In range of studies was made cast steel test castings withcomposite surface layer, which usability for industrial applications was estimated by criterion of hardness and aberasive wear resistance of type metal-mineral and quality of joint cast steel – (Fe-Cr-C. Based on conducted studies a thesis, that composite surface layer arise from liquid state, was formulated. Moreover, possible is control of composite layer thickness and its hardness by suitable selection of parameters i.e. thickness of insert, pouring temperature and solidification modulus of casting. Possibility of technology application of composite surface layer in manufacture of cast steel slide bush for combined cutter loader is presented.

  10. Producing of multicomponent and composite surface layers

    International Nuclear Information System (INIS)

    Wierzchon, T.; Bielinski, P.; Michalski, A.

    1995-01-01

    The paper presents a new method of producing multicomponent and composite layers on steel substrate. The combination of nickel plating with glow-discharge bordering or impulse-plasma deposition method gives an opportunity to obtain good properties of surface layers. The results of examinations of carbon 45 (0.45%C) steel, nickel plated and then borided under glow discharge conditions or covered with TiN layers are presented. The corrosion and friction wear resistance of such layers are markedly higher than for layer produced on non nickel plated substrates. (author). 19 refs, 5 figs

  11. Infrared active thermography for surface layer characterization

    International Nuclear Information System (INIS)

    Semerok, A.; Fomichev, S.; Farcage, D.; Sortais, C.; Courtois, X.

    2006-05-01

    Deposited layer characterization was stated as the main goal of our studies for 2006. The investigations by DRFC/SIPP/GCFP (CEA Cadarache) were performed with the procedure of surface temperature measurements based on infrared thermography with synchronous demodulation (Lock-in Thermography). It was applied to provide the temperature surface monitoring during the modulated heating by illumination. The obtained 2D-cartography revealed the zones with a weak heat transfer resulting from a low layer/surface adhesion or poor layer thermal conductivity. The obtained lock-in cartography data should be regarded only as qualitative. For deposited layers characterization (layer depth, adhesion with the substrate), the active laser pyrometer measurements with the developed experimental device were made in LILM laboratory (CEA Saclay). Active surface pyrometry with repetitive laser heating can provide both qualitative and quantitative data on the first layer and the interface with the substrate. A 3D-numerical model of graphite deposited layer heating by a pulsed high repetition rate laser beam was developed to determine the heated surface temperature with a high temporal and spatial resolution. The theoretical data obtained with 3D-numerical model for surface heating were compared with the experimental results. It was demonstrated that for the given optical and thermo-physical parameters of materials, the theoretical temperatures may be fitted with the experimental results to assess certain unknown parameters of the layer (thermal contact resistance, diffusivity, thickness, porosity, ). Based on the comparison of the obtained experimental and theoretical results, the deposited layer characterization was made. The results of the investigations on Active Laser Pyrometry and Lock-in Thermography demonstrated that the methods can provide qualitative and quantitative data on the deposited layer and on the layer/substrate interface. The correlation and cross-check of the results

  12. Surface-layer gusts for aircraft operation

    DEFF Research Database (Denmark)

    Young, G.S.; Kristensen, L.

    1992-01-01

    We use Monin-Obukhov similarity theory to extend the Kristensen et al. (1991) aviation gust estimation technique from the neutral to the diabatic surface layer. Example calculations demonstrate the importance of this correction. Simple stability class methods using only standard aviation surface ...

  13. Surface layer effects on waste glass corrosion

    International Nuclear Information System (INIS)

    Feng, X.

    1993-01-01

    Water contact subjects waste glass to chemical attack that results in the formation of surface alteration layers. Two principal hypotheses have been advanced concerning the effect of surface alteration layers on continued glass corrosion: (1) they act as a mass transport barrier and (2) they influence the chemical affinity of the glass reaction. In general, transport barrier effects have been found to be less important than affinity effects in the corrosion of most high-level nuclear waste glasses. However, they can be important under some circumstances, for example, in a very alkaline solution, in leachants containing Mg ions, or under conditions where the matrix dissolution rate is very low. The latter suggests that physical barrier effect may affect the long-term glass dissolution rate. Surface layers influence glass reaction affinity through the effects of the altered glass and secondary phases on the solution chemistry. The reaction affinity may be controlled by various precipitates and crystalline phases, amorphous silica phases, gel layer, or all the components of the glass. The surface alteration layers influence radionuclide release mainly through colloid formation, crystalline phase incorporation, and gel layer retention. This paper reviews current understanding and uncertainties

  14. The surface roughness and planetary boundary layer

    Science.gov (United States)

    Telford, James W.

    1980-03-01

    Applications of the entrainment process to layers at the boundary, which meet the self similarity requirements of the logarithmic profile, have been studied. By accepting that turbulence has dominating scales related in scale length to the height above the surface, a layer structure is postulated wherein exchange is rapid enough to keep the layers internally uniform. The diffusion rate is then controlled by entrainment between layers. It has been shown that theoretical relationships derived on the basis of using a single layer of this type give quantitatively correct factors relating the turbulence, wind and shear stress for very rough surface conditions. For less rough surfaces, the surface boundary layer can be divided into several layers interacting by entrainment across each interface. This analysis leads to the following quantitatively correct formula compared to published measurements. 1 24_2004_Article_BF00877766_TeX2GIFE1.gif {σ _w }/{u^* } = ( {2/{9Aa}} )^{{1/4}} ( {1 - 3^{{1/2}{ a/k{d_n }/z{σ _w }/{u^* }z/L} )^{{1/4}} = 1.28(1 - 0.945({{σ _w }/{u^* }}}) {{z/L}})^{{1/4 where u^* = ( {{tau/ρ}}^{{1/2}}, σ w is the standard deviation of the vertical velocity, z is the height and L is the Obukhov scale lenght. The constants a, A, k and d n are the entrainment constant, the turbulence decay constant, Von Karman's constant, and the layer depth derived from the theory. Of these, a and A, are universal constants and not empirically determined for the boundary layer. Thus the turbulence needed for the plume model of convection, which resides above these layers and reaches to the inversion, is determined by the shear stress and the heat flux in the surface layers. This model applies to convection in cool air over a warm sea. The whole field is now determined except for the temperature of the air relative to the water, and the wind, which need a further parameter describing sea surface roughness. As a first stop to describing a surface where roughness elements

  15. Surface shear rheology of saponin adsorption layers.

    Science.gov (United States)

    Golemanov, Konstantin; Tcholakova, Slavka; Denkov, Nikolai; Pelan, Edward; Stoyanov, Simeon D

    2012-08-21

    Saponins are a wide class of natural surfactants, with molecules containing a rigid hydrophobic group (triterpenoid or steroid), connected via glycoside bonds to hydrophilic oligosaccharide chains. These surfactants are very good foam stabiliziers and emulsifiers, and show a range of nontrivial biological activities. The molecular mechanisms behind these unusual properties are unknown, and, therefore, the saponins have attracted significant research interest in recent years. In our previous study (Stanimirova et al. Langmuir 2011, 27, 12486-12498), we showed that the triterpenoid saponins extracted from Quillaja saponaria plant (Quillaja saponins) formed adsorption layers with unusually high surface dilatational elasticity, 280 ± 30 mN/m. In this Article, we study the shear rheological properties of the adsorption layers of Quillaja saponins. In addition, we study the surface shear rheological properties of Yucca saponins, which are of steroid type. The experimental results show that the adsorption layers of Yucca saponins exhibit purely viscous rheological response, even at the lowest shear stress applied, whereas the adsorption layers of Quillaja saponins behave like a viscoelastic two-dimensional body. For Quillaja saponins, a single master curve describes the data for the viscoelastic creep compliance versus deformation time, up to a certain critical value of the applied shear stress. Above this value, the layer compliance increases, and the adsorption layers eventually transform into viscous ones. The experimental creep-recovery curves for the viscoelastic layers are fitted very well by compound Voigt rheological model. The obtained results are discussed from the viewpoint of the layer structure and the possible molecular mechanisms, governing the rheological response of the saponin adsorption layers.

  16. Microthermal Instrument for Measuring Surface Layer Seeing

    Science.gov (United States)

    Li, Xue-Bao; Zheng, Yan-Fang; Deng, Lin Hua; Xu, Guang

    2012-02-01

    Microthermal fluctuations are introduced by atmospheric turbulence very near the ground. In order to detect microthermal fluctuations at Fuxian Solar Observatory (FSO), a microthermal instrument has been developed. The microthermal instrument consists of a microthermal sensor, which is based on a Wheatstone bridge circuit and uses fine tungsten filaments as resistance temperature detectors, an associated signal processing unit, and a data collection, & communication subsystem. In this paper, after a brief introduction to surface layer seeing, we discuss the instrumentation behind the microthermal detector we have developed and then present the results obtained. The results of the evaluation indicate that the effect of the turbulent surface boundary layer to astronomical seeing would become sufficiently small when installing a telescope at a height of 16m or higher from the ground at FSO.

  17. Dynamic air layer on textured superhydrophobic surfaces

    KAUST Repository

    Vakarelski, Ivan Uriev

    2013-09-03

    We provide an experimental demonstration that a novel macroscopic, dynamic continuous air layer or plastron can be sustained indefinitely on textured superhydrophobic surfaces in air-supersaturated water by a natural gas influx mechanism. This type of plastron is an intermediate state between Leidenfrost vapor layers on superheated surfaces and the equilibrium Cassie-Baxter wetting state on textured superhydrophobic surfaces. We show that such a plastron can be sustained on the surface of a centimeter-sized superhydrophobic sphere immersed in heated water and variations of its dynamic behavior with air saturation of the water can be regulated by rapid changes of the water temperature. The simple experimental setup allows for quantification of the air flux into the plastron and identification of the air transport model of the plastron growth. Both the observed growth dynamics of such plastrons and millimeter-sized air bubbles seeded on the hydrophilic surface under identical air-supersaturated solution conditions are consistent with the predictions of a well-mixed gas transport model. © 2013 American Chemical Society.

  18. Organic light emitting diode with surface modification layer

    Science.gov (United States)

    Basil, John D.; Bhandari, Abhinav; Buhay, Harry; Arbab, Mehran; Marietti, Gary J.

    2017-09-12

    An organic light emitting diode (10) includes a substrate (12) having a first surface (14) and a second surface (16), a first electrode (32), and a second electrode (38). An emissive layer (36) is located between the first electrode (32) and the second electrode (38). The organic light emitting diode (10) further includes a surface modification layer (18). The surface modification layer (18) includes a non-planar surface (30, 52).

  19. System for removing contaminated surface layers

    International Nuclear Information System (INIS)

    Yoshikawa, Kozo.

    1987-04-01

    The object of the present invention is to offer a new type of useful decontamination system, with which the contaminated surface layers can be removed effectively by injection of such solid microparticles. Liquid carbon dioxide is passed from a liquid carbon dioxide tank via the carbon dioxide supply line into the system for injecting solid carbon dioxide particles. Part of the liquid carbon dioxide introduced into the system is converted to solid carbon dioxide particles by the temperature drop resulting from adiabatic expansion in the carbon dioxide expansion space of the injection system. The solid carbon dioxide particles reach the injection nozzle, which is connected through the expansion space. The carbon dioxide microparticles are further cooled and accelerated by nitrogen gas injected from the nitrogen gas nozzle at the tip of the nitrogen gas supply line, which is connected to a liquid nitrogen tank. The cooled and accelerated solid carbon dioxide microparticles are injected from the injection nozzle for the solid carbon dioxide and directed against the contaminated surface to be cleaned, and, as a result, the surface contamination is removed

  20. ESL Multilevel Handbook.

    Science.gov (United States)

    Clark, Melvin G.

    This guide is designed for teachers of multilevel classes in English as a Second Language (ESL) at the adult level. The first section discusses principles, methods, and techniques for classroom instruction, including student grouping, appropriate ESL teaching methods (audiolingual, vocational, language experience, natural approach,…

  1. Acoustic tomography in the atmospheric surface layer

    Directory of Open Access Journals (Sweden)

    A. Ziemann

    Full Text Available Acoustic tomography is presented as a technique for remote monitoring of meteorological quantities. This method and a special algorithm of analysis can directly produce area-averaged values of meteorological parameters. As a result consistent data will be obtained for validation of numerical atmospheric micro-scale models. Such a measuring system can complement conventional point measurements over different surfaces. The procedure of acoustic tomography uses the horizontal propagation of sound waves in the atmospheric surface layer. Therefore, to provide a general overview of sound propagation under various atmospheric conditions a two-dimensional ray-tracing model according to a modified version of Snell's law is used. The state of the crossed atmosphere can be estimated from measurements of acoustic travel time between sources and receivers at different points. Derivation of area-averaged values of the sound speed and furthermore of air temperature results from the inversion of travel time values for all acoustic paths. Thereby, the applied straight ray two-dimensional tomographic model using SIRT (simultaneous iterative reconstruction technique is characterised as a method with small computational requirements, satisfactory convergence and stability properties as well as simple handling, especially, during online evaluation.

    Key words. Meteorology and atmospheric dynamics (turbulence; instruments and techniques.

  2. Improve oxidation resistance at high temperature by nanocrystalline surface layer

    OpenAIRE

    Xia, Z. X.; Zhang, C.; Huang, X. F.; Liu, W. B.; Yang, Z. G.

    2015-01-01

    An interesting change of scale sequence occurred during oxidation of nanocrystalline surface layer by means of a surface mechanical attrition treatment. The three-layer oxide structure from the surface towards the matrix is Fe3O4, spinel FeCr2O4 and corundum (Fe,Cr)2O3, which is different from the typical two-layer scale consisted of an Fe3O4 outer layer and an FeCr2O4 inner layer in conventional P91 steel. The diffusivity of Cr, Fe and O is enhanced concurrently in the nanocrystalline surfac...

  3. Exploring Scintillometry in the Stable Atmospheric Surface Layer

    NARCIS (Netherlands)

    Hartogensis, O.K.

    2006-01-01

    The main objective of this thesis is to investigate observation methods of heat and momentum exchange and key variables that characterise turbulence in the atmospheric stable surface layer (SSL), a layer defined as the lower part of the stable boundary layer (SBL) where surface fluxes do not change

  4. ESL Placement and Schools

    Science.gov (United States)

    Callahan, Rebecca; Wilkinson, Lindsey; Muller, Chandra; Frisco, Michelle

    2010-01-01

    In this study, the authors explore English as a Second Language (ESL) placement as a measure of how schools label and process immigrant students. Using propensity score matching and data from the Adolescent Health and Academic Achievement Study and the National Longitudinal Study of Adolescent Health, the authors estimate the effect of ESL placement on immigrant achievement. In schools with more immigrant students, the authors find that ESL placement results in higher levels of academic performance; in schools with few immigrant students, the effect reverses. This is not to suggest a one-size-fits-all policy; many immigrant students, regardless of school composition, generational status, or ESL placement, struggle to achieve at levels sufficient for acceptance to a 4-year university. This study offers several factors to be taken into consideration as schools develop policies and practices to provide immigrant students opportunities to learn. PMID:20617111

  5. Observations of the atmospheric surface layer parameters over a ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    1999-08-11

    Aug 11, 1999 ... This paper discusses the observations of the Atmospheric Surface Layer (ASL) parameters dur- ing the solar eclipse of August 11th, 1999. Intensive surface layer experiments were conducted at. Ahmedabad (23◦21 N, 72◦36 E), the western part of India, which was close to the totality path. This rare event ...

  6. 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.

  7. Contact mechanics for layered materials with randomly rough surfaces.

    Science.gov (United States)

    Persson, B N J

    2012-03-07

    The contact mechanics model of Persson is applied to layered materials. We calculate the M function, which relates the surface stress to the surface displacement, for a layered material, where the top layer (thickness d) has different elastic properties than the semi-infinite solid below. Numerical results for the contact area as a function of the magnification are presented for several cases. As an application, we calculate the fluid leak rate for laminated rubber seals.

  8. Assessment of WRF Surface Layer Formulations Over a Complex Terrain

    Science.gov (United States)

    Srivastava, P.; Sharan, M.

    2017-12-01

    The accurate and efficient estimation of surface turbulent fluxes is crucial to predict an adequate atmospheric evolution by atmospheric models. The Monin-Obukhov similarity theory, which is used to compute these fluxes in numerical models, utilizes the empirical stability correction functions. In the present study, impact of various functional forms of similarity functions on the computation of the surface fluxes under both unstable and stable stratification is analyzed. In addition, this study compares two surface layer parametrization schemes in the Weather Research and Forecasting model over Ranchi (India). The model is run with three nested domains at a high resolution (1 Km) for `five' 4-day periods covering 15 days of Premonsoon season. The two surface layer schemes chosen for the analysis includes MM5 surface layer scheme having Businger-Dyer similarity functions, and revised MM5 scheme utilizing the functions those are valid for full ranges of atmospheric stabilities. The five planetary boundary layer (PBL) schemes are selected to assess the influence of the surface layer schemes on the structure of the boundary layer. The schemes are- Asymmetric Convective Model Version 2 (ACM2), Bougeault-Lacarrere (Boulac), Medium Range Forecast (MRF), Mellor-Yamada-Nakanishi-Niino (MYNN), and Yonsei University (YSU) PBL schemes. The impact of surface layer parametrizations on the near surface diagnostic variables is analyzed and results are compared with the observations.The bias in the 2 m temperature (T2) and 10 m wind speed (U) across the PBL schemes is very small and each PBL scheme is able to reproduce the diurnal variation of T2 irrespective of the surface layer scheme used for the simulations. A relatively higher value nocturnal T2 is predicted with the revised MM5 surface layer scheme as compared to that obtained with the old MM5 scheme, while both the surface layer schemes reproduce almost similar T2 during convective conditions. However, compare to the

  9. Exploring Service Logic in ESL

    Science.gov (United States)

    Walker, John

    2013-01-01

    ESL is both a professional educational service and, particularly in post-compulsory contexts, a commercial activity. The effective management of ESL programs can secure quality outcomes for practitioners and students. Nevertheless, writings on ESL management do not figure prominently in the literature. In particular, the association between…

  10. Preservation of Archaeal Surface Layer Structure During Mineralization

    Science.gov (United States)

    Kish, Adrienne; Miot, Jennyfer; Lombard, Carine; Guigner, Jean-Michel; Bernard, Sylvain; Zirah, Séverine; Guyot, François

    2016-05-01

    Proteinaceous surface layers (S-layers) are highly ordered, crystalline structures commonly found in prokaryotic cell envelopes that augment their structural stability and modify interactions with metals in the environment. While mineral formation associated with S-layers has previously been noted, the mechanisms were unconstrained. Using Sulfolobus acidocaldarius a hyperthermophilic archaeon native to metal-enriched environments and possessing a cell envelope composed only of a S-layer and a lipid cell membrane, we describe a passive process of iron phosphate nucleation and growth within the S-layer of cells and cell-free S-layer “ghosts” during incubation in a Fe-rich medium, independently of metabolic activity. This process followed five steps: (1) initial formation of mineral patches associated with S-layer; (2) patch expansion; (3) patch connection; (4) formation of a continuous mineral encrusted layer at the cell surface; (5) early stages of S-layer fossilization via growth of the extracellular mineralized layer and the mineralization of cytosolic face of the cell membrane. At more advanced stages of encrustation, encrusted outer membrane vesicles are formed, likely in an attempt to remove damaged S-layer proteins. The S-layer structure remains strikingly well preserved even upon the final step of encrustation, offering potential biosignatures to be looked for in the fossil record.

  11. Preservation of Archaeal Surface Layer Structure During Mineralization

    Science.gov (United States)

    Kish, Adrienne; Miot, Jennyfer; Lombard, Carine; Guigner, Jean-Michel; Bernard, Sylvain; Zirah, Séverine; Guyot, François

    2016-01-01

    Proteinaceous surface layers (S-layers) are highly ordered, crystalline structures commonly found in prokaryotic cell envelopes that augment their structural stability and modify interactions with metals in the environment. While mineral formation associated with S-layers has previously been noted, the mechanisms were unconstrained. Using Sulfolobus acidocaldarius a hyperthermophilic archaeon native to metal-enriched environments and possessing a cell envelope composed only of a S-layer and a lipid cell membrane, we describe a passive process of iron phosphate nucleation and growth within the S-layer of cells and cell-free S-layer “ghosts” during incubation in a Fe-rich medium, independently of metabolic activity. This process followed five steps: (1) initial formation of mineral patches associated with S-layer; (2) patch expansion; (3) patch connection; (4) formation of a continuous mineral encrusted layer at the cell surface; (5) early stages of S-layer fossilization via growth of the extracellular mineralized layer and the mineralization of cytosolic face of the cell membrane. At more advanced stages of encrustation, encrusted outer membrane vesicles are formed, likely in an attempt to remove damaged S-layer proteins. The S-layer structure remains strikingly well preserved even upon the final step of encrustation, offering potential biosignatures to be looked for in the fossil record. PMID:27221593

  12. Change of Surface Roughness and Planetary Boundary Layer

    DEFF Research Database (Denmark)

    Jensen, Niels Otto

    1978-01-01

    The ratio between upstream and far downstream surface friction velocities relative to a change in surface roughness is given on the basis of results from surface Rossby number similarity theory. By simple theories for the internal boundary layer, which are found to compare quite well with recent ...

  13. Surface plasmon polariton modulator with optimized active layer

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Lavrinenko, Andrei

    2012-01-01

    A multilayered waveguide, which supports surface plasmon polaritons, is considered as an absorption modulator. The waveguide core consists of a silicon nitride layer and ultrathin layer with the varied carrier density embedded between two silver plates, which also serve as electrodes. Under apply...

  14. 2nd international conference on ion beam surface layer analysis

    International Nuclear Information System (INIS)

    1975-01-01

    The papers of this conference are concerned with the fundamental aspects and with the application of surface layer analysis. It is reported amongst others about backscattering analysis, Auger electron spectroscopy, channelling and microprobe. (HPOE) [de

  15. The physical structure of the oceanic surface-layer

    Energy Technology Data Exchange (ETDEWEB)

    Fedorov, K.N.

    1981-01-01

    A study is presented of the structure of the near-surface layer of the ocean under various hydrometeorological conditions. Such a study allows the isolation of border measures for a four characteristic regime for the top ocean layer: 1) intensive wind-wave mixing; 2) Langmuir circulation; 3) intense solar heating during still and calm weather (with and without internal wave modulations); 4) a pressing-out of surface sediment. It is demonstrated that the spatial temperature change in the ocean surface, the thermal structure, and the heat attainment in the top layer have various characteristics during different regimes and this must be considered during the measuring of the ocean surface temperature with the contact method as well as during the comparison of contact and satallite data on the ocean surface temperature. The necessity for more research in this area is underscored.

  16. Surface-layer lattices as patterning element for multimeric extremozymes.

    Science.gov (United States)

    Ferner-Ortner-Bleckmann, Judith; Gelbmann, Nicola; Tesarz, Manfred; Egelseer, Eva M; Sleytr, Uwe B

    2013-11-25

    A promising new approach for the production of biocatalysts comprises the use of surface-layer (S-layer) lattices that present functional multimeric enzymes on their surface, thereby guaranteeing most accurate spatial distribution and orientation, as well as maximal effectiveness and stability of these enzymes. For proof of concept, a tetrameric and a trimeric extremozyme are chosen for the construction of S-layer/extremozyme fusion proteins. By using a flexible peptide linker, either one monomer of the tetrameric xylose isomerase XylA from the thermophilic Thermoanaerobacterium strain JW/SL-YS 489 or, in another approach, one monomer of the trimeric carbonic anhydrase from the methanogenic archaeon Methanosarcina thermophila are genetically linked to one monomer of the S-layer protein SbpA of Lysinibacillus sphaericus CCM 2177. After isolation and purification, the self-assembly properties of both S-layer fusion proteins as well as the specific activity of the fused enzymes are confirmed, thus indicating that the S-layer protein moiety does not influence the nature of the multimeric enzymes and vice versa. By recrystallization of the S-layer/extremozyme fusion proteins on solid supports, the active enzyme multimers are exposed on the surface of the square S-layer lattice with 13.1 nm spacing. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Grammar and Teaching ESL

    Science.gov (United States)

    Morrissey, Glenda; Young, Barbara N.

    2005-01-01

    The variety of theories relating to teaching ESL learners leads to contradictory ideas about teaching a second language. This paper focuses on the continuing importance of grammar in teaching and the current resurgence in interest in returning to grammar as an important component in the classroom.

  18. Surface Layer Turbulence and Aerosol Profiles During MAPTIP

    NARCIS (Netherlands)

    Davidson, K.L.; Frederickson, P.A.; Leeuw, G. de

    1995-01-01

    The Naval Postgraduate School (NPS) and the TNO Physics and Electronics Laboratory (TNO-FEL) deployed in situ sensors near and on Meetpost Noordwijk (MPN) during MAPTIP to describe the surface layer processes and also to evaluate models for near-surface aerosol profiles. Vertical profiles of aerosol

  19. Whisker Formation On Galvanic Tin Surface Layer

    Directory of Open Access Journals (Sweden)

    Radanyi A.L.

    2015-06-01

    Full Text Available The present work reports the effect of substrate composition, thickness of the tin electroplate and its morphology on pressure-induced tin whisker formation. Pure tin deposits of different thickness were obtained on a copper and brass substrates using methane sulfonic industrial bath. The deposits were compressed by a steel bearing ball forming imprint on the surface. The microstructure of tin whiskers obtained at the boundary of each imprint, their length and number were studied using both light and scanning electron microscopy. It was shown that the most intensive formation and growth of whiskers was observed in the first two hours. In general, brass substrate was shown to be more prone to whisker formation than copper independently of the tin coating thickness. The results have been compared with industrial bright tin finish on control unit socket leads and proposals have been made as to modification of the production process in order to minimize the risk of whiskering.

  20. Multi-layer enhancement to polysilicon surface-micromachining technology

    Energy Technology Data Exchange (ETDEWEB)

    Sniegowski, J.J.; Rodgers, M.S. [Sandia National Labs., Albuquerque, NM (United States). Intelligent Micromachine Dept.

    1997-10-01

    A multi-level polysilicon surface-micromachining technology consisting of 5 layers of polysilicon is presented. Surface topography and film mechanical stress are the major impediments encountered in the development of a multilayer surface-micromachining process. However, excellent mechanical film characteristics have been obtained through the use of chemical-mechanical polishing for planarization of topography and by proper sequencing of film deposition with thermal anneals. Examples of operating microactuators, geared power-transfer mechanisms, and optical elements demonstrate the mechanical advantages of construction with 5 polysilicon layers.

  1. Double Charged Surface Layers in Lead Halide Perovskite Crystals

    KAUST Repository

    Sarmah, Smritakshi P.

    2017-02-01

    Understanding defect chemistry, particularly ion migration, and its significant effect on the surface’s optical and electronic properties is one of the major challenges impeding the development of hybrid perovskite-based devices. Here, using both experimental and theoretical approaches, we demonstrated that the surface layers of the perovskite crystals may acquire a high concentration of positively charged vacancies with the complementary negatively charged halide ions pushed to the surface. This charge separation near the surface generates an electric field that can induce an increase of optical band gap in the surface layers relative to the bulk. We found that the charge separation, electric field, and the amplitude of shift in the bandgap strongly depend on the halides and organic moieties of perovskite crystals. Our findings reveal the peculiarity of surface effects that are currently limiting the applications of perovskite crystals and more importantly explain their origins, thus enabling viable surface passivation strategies to remediate them.

  2. Atomic and molecular layer deposition for surface modification

    International Nuclear Information System (INIS)

    Vähä-Nissi, Mika; Sievänen, Jenni; Salo, Erkki; Heikkilä, Pirjo; Kenttä, Eija; Johansson, Leena-Sisko; Koskinen, Jorma T.; Harlin, Ali

    2014-01-01

    Atomic and molecular layer deposition (ALD and MLD, respectively) techniques are based on repeated cycles of gas–solid surface reactions. A partial monolayer of atoms or molecules is deposited to the surface during a single deposition cycle, enabling tailored film composition in principle down to molecular resolution on ideal surfaces. Typically ALD/MLD has been used for applications where uniform and pinhole free thin film is a necessity even on 3D surfaces. However, thin – even non-uniform – atomic and molecular deposited layers can also be used to tailor the surface characteristics of different non-ideal substrates. For example, print quality of inkjet printing on polymer films and penetration of water into porous nonwovens can be adjusted with low-temperature deposited metal oxide. In addition, adhesion of extrusion coated biopolymer to inorganic oxides can be improved with a hybrid layer based on lactic acid. - Graphical abstract: Print quality of a polylactide film surface modified with atomic layer deposition prior to inkjet printing (360 dpi) with an aqueous ink. Number of printed dots illustrated as a function of 0, 5, 15 and 25 deposition cycles of trimethylaluminum and water. - Highlights: • ALD/MLD can be used to adjust surface characteristics of films and fiber materials. • Hydrophobicity after few deposition cycles of Al 2 O 3 due to e.g. complex formation. • Same effect on cellulosic fabrics observed with low temperature deposited TiO 2 . • Different film growth and oxidation potential with different precursors. • Hybrid layer on inorganic layer can be used to improve adhesion of polymer melt

  3. Atomic and molecular layer deposition for surface modification

    Energy Technology Data Exchange (ETDEWEB)

    Vähä-Nissi, Mika, E-mail: mika.vaha-nissi@vtt.fi [VTT Technical Research Centre of Finland, PO Box 1000, FI‐02044 VTT (Finland); Sievänen, Jenni; Salo, Erkki; Heikkilä, Pirjo; Kenttä, Eija [VTT Technical Research Centre of Finland, PO Box 1000, FI‐02044 VTT (Finland); Johansson, Leena-Sisko, E-mail: leena-sisko.johansson@aalto.fi [Aalto University, School of Chemical Technology, Department of Forest Products Technology, PO Box 16100, FI‐00076 AALTO (Finland); Koskinen, Jorma T.; Harlin, Ali [VTT Technical Research Centre of Finland, PO Box 1000, FI‐02044 VTT (Finland)

    2014-06-01

    Atomic and molecular layer deposition (ALD and MLD, respectively) techniques are based on repeated cycles of gas–solid surface reactions. A partial monolayer of atoms or molecules is deposited to the surface during a single deposition cycle, enabling tailored film composition in principle down to molecular resolution on ideal surfaces. Typically ALD/MLD has been used for applications where uniform and pinhole free thin film is a necessity even on 3D surfaces. However, thin – even non-uniform – atomic and molecular deposited layers can also be used to tailor the surface characteristics of different non-ideal substrates. For example, print quality of inkjet printing on polymer films and penetration of water into porous nonwovens can be adjusted with low-temperature deposited metal oxide. In addition, adhesion of extrusion coated biopolymer to inorganic oxides can be improved with a hybrid layer based on lactic acid. - Graphical abstract: Print quality of a polylactide film surface modified with atomic layer deposition prior to inkjet printing (360 dpi) with an aqueous ink. Number of printed dots illustrated as a function of 0, 5, 15 and 25 deposition cycles of trimethylaluminum and water. - Highlights: • ALD/MLD can be used to adjust surface characteristics of films and fiber materials. • Hydrophobicity after few deposition cycles of Al{sub 2}O{sub 3} due to e.g. complex formation. • Same effect on cellulosic fabrics observed with low temperature deposited TiO{sub 2}. • Different film growth and oxidation potential with different precursors. • Hybrid layer on inorganic layer can be used to improve adhesion of polymer melt.

  4. Seasonality in onshore normalized wind profiles above the surface layer

    DEFF Research Database (Denmark)

    Nissen, Jesper Nielsen; Gryning, Sven-Erik

    2010-01-01

    This work aims to study the seasonal difference in normalized wind speed above the surface layer as it is observed at the 160 m high mast at the coastal site Høvsøre at winds from the sea (westerly). Normalized and stability averaged wind speeds above the surface layer are observed to be 20 to 50......% larger in the winter/spring seasons compared to the summer/autumn seasons at winds from west within the same atmospheric stability class. A method combining the mesoscale model, COAMPS, and observations of the surface stability of the marine boundary layer is presented. The objective of the method...... is to reconstruct the seasonal signal in normalized wind speed and identify the physical process behind. The method proved reasonably successful in capturing the relative difference in wind speed between seasons, indicating that the simulated physical processes are likely candidates to the observed seasonal signal...

  5. Analysis of Surface Waves in Saturated Layered Poroelastic Half-Spaces Using the Thin Layer Method

    Science.gov (United States)

    Chai, Huayou; Cui, Yujun; Zhang, Dianji

    2018-03-01

    There are multiple modes of surface waves in saturated layered poroelastic half-spaces. The phase velocity and the attenuation of the modes are frequency dependent. The frequency behaviour of the modes can be studied using the layer transfer, stiffness and the transmission/reflection matrix methods. However, it is very difficult to find the complex roots of the determinants because the entries of the matrices involve the complex exponential functions of the wavenumber and the thickness of layer. To overcome this difficulty, the entries in the matrix are expressed in the form of algebraic functions using the thin layer method. Thus, the eigenvalues and eigenvectors can be easily solved using the matrix decomposition techniques instead of the root-searching ones. Some of the eigenvalues correspond to the wavenumbers of the surface waves, and can be picked out based on the characteristics of the surface waves. The frequency behaviour, variations of the pore pressure and the skeleton's displacements with the depth can be then investigated from the corresponding eigenvalues and eigenvectors, respectively. The method is verified by comparing the analytical and the discrete results in the saturated poroelastic half-space with the permeable surface. The method is applied to appreciate the effects of an impermeable surface on Rayleigh waves (R-waves) and the existence of Stoneley waves in the poroelastic half-space. The frequency behaviour of Rayleigh waves in three typical layered poroelastic half-spaces is also analyzed.

  6. Surface tension in plasmas related to double layer formation

    Energy Technology Data Exchange (ETDEWEB)

    Popescu, Sebastian; Lozneanu, Erzilia [Al. I. Cuza University, Dept. of Plasma Physics, Iasi (Romania)

    2001-07-01

    Self-organized space charge configurations bordered by electric double layers appear in plasma as the result of the transition into a state characterized by local minimum of the free energy. Considering the self-assemblage process of such a complex well-confined space-charge configuration in plasma, known by the name of ball of fire, as a nucleation process, it becomes possible to define an equivalent surface tension for the double layer that covers the core of the ball of fire and to make some predictions for its surface tension coefficient and capacitance. (author)

  7. Translation in ESL Classes

    Directory of Open Access Journals (Sweden)

    Nagy Imola Katalin

    2015-12-01

    Full Text Available The problem of translation in foreign language classes cannot be dealt with unless we attempt to make an overview of what translation meant for language teaching in different periods of language pedagogy. From the translation-oriented grammar-translation method through the complete ban on translation and mother tongue during the times of the audio-lingual approaches, we have come today to reconsider the role and status of translation in ESL classes. This article attempts to advocate for translation as a useful ESL class activity, which can completely fulfil the requirements of communicativeness. We also attempt to identify some activities and games, which rely on translation in some books published in the 1990s and the 2000s.

  8. Modification of surfaces and surface layers by non equilibrium processes

    International Nuclear Information System (INIS)

    Beamson, G.; Brennan, W.J.; Clark, D.T.; Howard, J.

    1988-01-01

    Plasmas are examples of non-equilibrium phenomena which are being used increasingly for the synthesis and modification of materials impossible by conventional routes. This paper introduces methods available by describing the construction and characteristics of some equipment used for the production of different types of plasmas and other non-equilibrium phenomena. This includes high energy ion beams. The special features, advantages and disadvantages of the techniques will be described. There are a multitude of potential application relevant to electronic, metallic, ceramic, and polymeric materials. However, scale-up from the laboratory to production equipment depends on establishing a better understanding of both the physics and chemistry of plasma as well as plasma-solid interactions. Examples are given of how such an understanding can be gained. The chemical analysis of polymer surfaces undergoing modification by inert gas, hydrogen or oxygen plasmas is shown to give physical information regarding the relative roles of diffusion of active species, and direct and radiative energy transfer from the plasma. Surface modification by plasma depositing a new material onto an existing substrate is discussed with particular reference to the deposition of amorphous carbon films. Applications of the unique properties of these films are outlined together with our current understanding of these properties based on chemical and physical methods of analysis of both the films and the plasmas producing them. Finally, surface modification by ion beams is briefly illustrated using examples from the electronics and metals industries where the modification has had a largely physical rather than chemical effect on the starting material. (orig.)

  9. Equivalent physical models and formulation of equivalent source layer in high-resolution EEG imaging

    Energy Technology Data Exchange (ETDEWEB)

    Yao Dezhong [School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu City, 610054, Sichuan Province (China); He Bin [The University of Illinois at Chicago, IL (United States)

    2003-11-07

    In high-resolution EEG imaging, both equivalent dipole layer (EDL) and equivalent charge layer (ECL) assumed to be located just above the cortical surface have been proposed as high-resolution imaging modalities or as intermediate steps to estimate the epicortical potential. Presented here are the equivalent physical models of these two equivalent source layers (ESL) which show that the strength of EDL is proportional to the surface potential of the layer when the outside of the layer is filled with an insulator, and that the strength of ECL is the normal current of the layer when the outside is filled with a perfect conductor. Based on these equivalent physical models, closed solutions of ECL and EDL corresponding to a dipole enclosed by a spherical layer are given. These results provide the theoretical basis of ESL applications in high-resolution EEG mapping.

  10. Equivalent physical models and formulation of equivalent source layer in high-resolution EEG imaging.

    Science.gov (United States)

    Yao, Dezhong; He, Bin

    2003-11-07

    In high-resolution EEG imaging, both equivalent dipole layer (EDL) and equivalent charge layer (ECL) assumed to be located just above the cortical surface have been proposed as high-resolution imaging modalities or as intermediate steps to estimate the epicortical potential. Presented here are the equivalent physical models of these two equivalent source layers (ESL) which show that the strength of EDL is proportional to the surface potential of the layer when the outside of the layer is filled with an insulator, and that the strength of ECL is the normal current of the layer when the outside is filled with a perfect conductor. Based on these equivalent physical models, closed solutions of ECL and EDL corresponding to a dipole enclosed by a spherical layer are given. These results provide the theoretical basis of ESL applications in high-resolution EEG mapping.

  11. Elastic layer under axisymmetric indentation and surface energy effects

    Science.gov (United States)

    Intarit, Pong-in; Senjuntichai, Teerapong; Rungamornrat, Jaroon

    2018-04-01

    In this paper, a continuum-based approach is adopted to investigate the contact problem of an elastic layer with finite thickness and rigid base subjected to axisymmetric indentation with the consideration of surface energy effects. A complete Gurtin-Murdoch surface elasticity is employed to consider the influence of surface stresses. The indentation problem of a rigid frictionless punch with arbitrary axisymmetric profiles is formulated by employing the displacement Green's functions, derived with the aid of Hankel integral transform technique. The problem is solved by assuming the contact pressure distribution in terms of a linear combination of admissible functions and undetermined coefficients. Those coefficients are then obtained by employing a collocation technique and an efficient numerical quadrature scheme. The accuracy of proposed solution technique is verified by comparing with existing solutions for rigid indentation on an elastic half-space. Selected numerical results for the indenters with flat-ended cylindrical and paraboloidal punch profiles are presented to portray the influence of surface energy effects on elastic fields of the finite layer. It is found that the presence of surface stresses renders the layer stiffer, and the size-dependent behavior of elastic fields is observed in the present solutions. In addition, the surface energy effects become more pronounced with smaller contact area; thus, the influence of surface energy cannot be ignored in the analysis of indentation problem especially when the indenter size is very small such as in the case of nanoindentation.

  12. The structure of alteration layers on cast glass surfaces

    International Nuclear Information System (INIS)

    Oversby, V.M.; Phinney, D.L.

    1991-11-01

    Alteration layers developed on SRL-165 simulated waste glasses in dilute sodium silicate/bicarbonate leaching solutions have been examined by Secondary Ionization Mass Spectroscopy (SIMS) using fine-scale, multiple-element depth profiling. Selected samples were examined with an imaging detector system, which demonstrated the horizontal homogeneity of the layer development at all depths within the layer. After 1 day of reaction at 90 degrees C the reaction layer shows depletion of glass elements to a depth of 0.2 μm. The surface of the layer in contact with the solution shows enrichment of Si, Al, and alkali elements even at this short reaction time, suggesting the early stages of development of secondary aluminosilicate phases. With increased reaction time, the layer thickens to about 1.3 μm at 91 days, while the evidence for aluminosilicate development at the surface of the layer becomes more prominent. Penetration of hydrogen into the ''unreacted'' glass proceeds to a depth of about 0.5 μm deeper than the alkali depletion zone. This suggests the mechanism of initial reaction of the glass is by attack of the silicate structure by molecular water or hydroxide ion rather than by alkali-hydrogen ion exchange. The simple structure of the layers developed in the silicate solution is in contrast to the complexity of layer structure found when glasses are reacted in deionized water. Since the conditions for geologic disposal will be closer to those used in the silicate leaching experiments, these results hold promise for the ability to model the system to predict long-term performance after disposal in a repository

  13. Vibrations of microemulsion droplets and vesicles with compressible surface layer

    Science.gov (United States)

    Lisy, V.; Brutovsky, B.; Zatovsky, A. V.

    1998-12-01

    The surface vibration spectra of liquid droplets with flexible interfaces, like microemulsion droplets or vesicles, are studied. As distinct from the previous theories, we proceed with exact solutions of hydrodynamic equations for incompressible bulk fluids inside and outside the droplet. The dynamical equations for the interface are those obtained by Lebedev and Muratov [JETP 68, 1011 (1989)] but with the improved continuity equation for the surface layer. Within the Helfrich's concept of the interfacial elasticity and taking into account the compressibility of the surface layer, the exact equation is obtained for the frequencies of the droplet vibrations. The equation describes uniformly a broad region of frequencies from the lowest, almost purely relaxation modes, up to the modes determined mainly by the change of the area per molecule of the layer. The dispersion laws for some of the modes are obtained analytically in the limits of large and small penetration depths of the corresponding waves. Our analysis corrects the previous results concerning the relaxation modes, the capillary wave frequency and the frequency of the mode connected with the fluctuations of molecules in the surface layer. An additional mode of this kind is obtained for almost incompressible layers. In the region corresponding to large penetration depths, a couple of modes exist with frequencies depending both on the surface elasticity and compressibility. In the limit of infinite compressibility of the layer, the lower of the two modes disappears. The conditions necessary for the existence of all the modes were specified. Some representative numerical solutions of the obtained equation are presented as depending on various values of the model parameters including those for realistic microemulsion systems.

  14. Structure and stability of surface passivation layers on semiconductor materials

    Science.gov (United States)

    Kluth, George Jonathan

    The structure and stability of passivating layers on silicon surfaces have been examined on the molecular level using the methods of surface science. Hydrogen-terminated surfaces were prepared through wet chemical treatment with ammonium fluoride. The oxidation of these surfaces was studied using high resolution electron energy loss spectroscopy (HREELS), which showed that oxidation occurred through oxygen insertion in silicon backbonds, while the hydrogen termination remained intact. Oxygen was observed in both the surface layer and bulk layers, suggesting that initial oxidation was not restricted to layer-by-layer growth. Because the surface did oxidize with time, other passivating treatments, specifically self-assembled monolayers, were examined. The thermal stability of alkylsiloxane monolayers on oxidized Si(100) was studied in vacuum. Using HREELS it was found that the monolayers were stable up to 740 K. Above that temperature, they began to decompose through cleavage of C-C bonds, resulting in a reduction in chain length. The thermal stability of alkyl monolayers, which form directly on silicon without requiring an oxide layer, was also examined. These monolayers were stable to 620 K, significantly lower than the alkylsiloxane monolayers. Desorption was accompanied by the appearance of Si-H bonds, suggesting that desorption took place through a hydrogen elimination reaction. The thermal behavior of these two different monolayers highlighted the importance of bonding between the surface and the chains. The bonding of alkylsiloxane monolayers was examined in more detail by forming them on both SiOsb2 and Sisb3Nsb4. It was found that cross linking between adjacent head groups was critical to the formation of high quality monolayers. Bonding between the chains and the surface was of secondary importance, but played a key role in the initial stages of growth, when nucleation occurred. The chemical stability of alkylsiloxane monolayers on oxidized silicon was also

  15. Quantized layer growth at liquid-crystal surfaces

    DEFF Research Database (Denmark)

    Ocko, B. M.; Braslau, A.; Pershan, P. S.

    1986-01-01

    of the specular reflectivity is consistent with a sinusoidal density modulation, starting at the surface and terminating abruptly, after an integral number of bilayers. As the transition is approached the number of layers increases in quantized steps from zero to five before the bulk undergoes a first...

  16. Whirlwinds and hairpins in the atmospheric surface layer

    NARCIS (Netherlands)

    Oncley, Steven P.; Hartogensis, O.K.; Tong, Chenning

    2016-01-01

    Vortices in the atmospheric surface layer are characterized using observations at unprecedented resolution from a fixed array of 31 turbulence sensors. During the day, these vortices likely are dust devils, though no visual observations are available for confirmation. At night, hairpin vortices

  17. Measurement of grassland evaporation using a surface-layer ...

    African Journals Online (AJOL)

    A dual-beam surface-layer scintillometer (SLS) was used to estimate sensible heat flux (H) every 2 min for a path length of either 50 or 101 m, for more than 30 months in a mesic grassland in eastern South Africa. The SLS method relies on Monin-Obukhov similarity theory, the correlation between the laser beam signal ...

  18. Body surface adaptations to boundary-layer dynamics

    NARCIS (Netherlands)

    Videler, J.J.

    1995-01-01

    Evolutionary processes have adapted nektonic animals to interact efficiently with the water that surrounds them. Not all these adaptations serve the same purpose. This paper concentrates on reduction of drag due to friction in the boundary layer close to the body surface. Mucus, compliant skins,

  19. The determination of turbulent structures in the atmospheric surface layer

    NARCIS (Netherlands)

    Schols, J.L.J.

    1984-01-01

    The turbulent flow in the atmospheric surface layer (ASL) contains turbulent structures, which are defined as spatially coherent, organized flow motions. 'Organized' means that characteristic patterns, observed at a point in space, occur almost simultaneously in more than one turbulence signal and

  20. DESIGN AND CALCULATION OF AERODROMECOAING WITH HEATED SURFACE LAYERS

    Directory of Open Access Journals (Sweden)

    Vadim G. Piskunov

    2009-04-01

    Full Text Available  The developed constructions with heated by surface layers for aerodromes and auto roads when developed composition of electroconductive concrete reinforced with chemical electrical conductive fibres being used was researched. The experimentally obtained characteristics of ended conductive concrete reinforced with fibers were presented. Calculation by developed heated construction of shell was made.

  1. Science Education and ESL Students

    Science.gov (United States)

    Allen, Heather; Park, Soonhye

    2011-01-01

    The number of students who learn English as a second language (ESL) in U.S. schools has grown significantly in the past decade. This segment of the student population increased by 56% between the 1994-95 and 2004-05 school years (NCLR 2007). As the ESL student population increases, many science teachers struggle to tailor instructional materials,…

  2. Electrical double layer interactions between dissimilar oxide surfaces with charge regulation and Stern-Grahame layers.

    Science.gov (United States)

    Chan, Derek Y C; Healy, Thomas W; Supasiti, Tharatorn; Usui, S

    2006-04-01

    Models of surfaces with intrinsic ionisable amphoteric surface sites governed by the dissociation of acid-base potential determining ion species together with the capacity for the adsorption of anion and cations of the supporting electrolyte are required to describe both the results of electrokinetic and titration measurements of inorganic oxides. The Gouy-Chapman-Stern-Grahame (CGSG) model is one such model that has been widely used in the literature. The electrical double layer interaction between two dissimilar CGSG surfaces has been studied by Usui recently [S. Usui, J. Colloid Interface Sci. 280 (2004) 113] where erroneous discontinuities in the slope of the pressure-separation relation were observed. We revisit this calculation and provide a simple general methodology to analyse the electrical double layer interaction between dissimilar ionisable surfaces with ion adsorption.

  3. Stabilization of Leidenfrost vapour layer by textured superhydrophobic surfaces.

    Science.gov (United States)

    Vakarelski, Ivan U; Patankar, Neelesh A; Marston, Jeremy O; Chan, Derek Y C; Thoroddsen, Sigurdur T

    2012-09-13

    In 1756, Leidenfrost observed that water drops skittered on a sufficiently hot skillet, owing to levitation by an evaporative vapour film. Such films are stable only when the hot surface is above a critical temperature, and are a central phenomenon in boiling. In this so-called Leidenfrost regime, the low thermal conductivity of the vapour layer inhibits heat transfer between the hot surface and the liquid. When the temperature of the cooling surface drops below the critical temperature, the vapour film collapses and the system enters a nucleate-boiling regime, which can result in vapour explosions that are particularly detrimental in certain contexts, such as in nuclear power plants. The presence of these vapour films can also reduce liquid-solid drag. Here we show how vapour film collapse can be completely suppressed at textured superhydrophobic surfaces. At a smooth hydrophobic surface, the vapour film still collapses on cooling, albeit at a reduced critical temperature, and the system switches explosively to nucleate boiling. In contrast, at textured, superhydrophobic surfaces, the vapour layer gradually relaxes until the surface is completely cooled, without exhibiting a nucleate-boiling phase. This result demonstrates that topological texture on superhydrophobic materials is critical in stabilizing the vapour layer and thus in controlling--by heat transfer--the liquid-gas phase transition at hot surfaces. This concept can potentially be applied to control other phase transitions, such as ice or frost formation, and to the design of low-drag surfaces at which the vapour phase is stabilized in the grooves of textures without heating.

  4. Stabilization of Leidenfrost vapour layer by textured superhydrophobic surfaces

    KAUST Repository

    Vakarelski, Ivan Uriev

    2012-09-12

    In 1756, Leidenfrost observed that water drops skittered on a sufficiently hot skillet, owing to levitation by an evaporative vapour film. Such films are stable only when the hot surface is above a critical temperature, and are a central phenomenon in boiling. In this so-called Leidenfrost regime, the low thermal conductivity of the vapour layer inhibits heat transfer between the hot surface and the liquid. When the temperature of the cooling surface drops below the critical temperature, the vapour film collapses and the system enters a nucleate-boiling regime, which can result in vapour explosions that are particularly detrimental in certain contexts, such as in nuclear power plants. The presence of these vapour films can also reduce liquid-solid drag. Here we show how vapour film collapse can be completely suppressed at textured superhydrophobic surfaces. At a smooth hydrophobic surface, the vapour film still collapses on cooling, albeit at a reduced critical temperature, and the system switches explosively to nucleate boiling. In contrast, at textured, superhydrophobic surfaces, the vapour layer gradually relaxes until the surface is completely cooled, without exhibiting a nucleate-boiling phase. This result demonstrates that topological texture on superhydrophobic materials is critical in stabilizing the vapour layer and thus in controlling-by heat transfer-the liquid-gas phase transition at hot surfaces. This concept can potentially be applied to control other phase transitions, such as ice or frost formation, and to the design of low-drag surfaces at which the vapour phase is stabilized in the grooves of textures without heating. © 2012 Macmillan Publishers Limited. All rights reserved.

  5. Surface layer temperature inversion in the Bay of Bengal: Main characteristics and related mechanisms

    Digital Repository Service at National Institute of Oceanography (India)

    Pankajakshan, T.; Suresh, I.; Gautham, S.; PrasannaKumar, S.; Lengaigne, M.; Rao, R.R; Neetu, S.; Hegde, A

    Surface layer temperature inversion (SLTI), a warm layer sandwiched between surface and subsurface colder waters, has been reported to frequently occur in conjunction with barrier layers in the Bay of Bengal (BoB), with potentially commensurable...

  6. THz detectors using surface Josephson plasma waves in layered superconductors

    International Nuclear Information System (INIS)

    Savel'ev, Sergey; Yampol'skii, Valery; Nori, Franco

    2006-01-01

    We describe a proposal for THz detectors based on the excitation of surface waves, in layered superconductors, at frequencies lower than the Josephson plasma frequency ω J . These waves propagate along the vacuum-superconductor interface and are attenuated in both transverse directions out of the surface (i.e., towards the superconductor and towards the vacuum). The surface Josephson plasma waves are also important for the complete suppression of the specular reflection from a sample (Wood's anomalies, used for gratings) and produce a huge enhancement of the wave absorption, which can be used for the detection of THz waves

  7. Double layer of platinum electrodes: Non-monotonic surface charging phenomena and negative double layer capacitance

    Science.gov (United States)

    Huang, Jun; Zhou, Tao; Zhang, Jianbo; Eikerling, Michael

    2018-01-01

    In this study, a refined double layer model of platinum electrodes accounting for chemisorbed oxygen species, oriented interfacial water molecules, and ion size effects in solution is presented. It results in a non-monotonic surface charging relation and a peculiar capacitance vs. potential curve with a maximum and possibly negative values in the potential regime of oxide-formation.

  8. Oxygen inhibition layer of composite resins: effects of layer thickness and surface layer treatment on the interlayer bond strength.

    Science.gov (United States)

    Bijelic-Donova, Jasmina; Garoushi, Sufyan; Lassila, Lippo V J; Vallittu, Pekka K

    2015-02-01

    An oxygen inhibition layer develops on surfaces exposed to air during polymerization of particulate filling composite. This study assessed the thickness of the oxygen inhibition layer of short-fiber-reinforced composite in comparison with conventional particulate filling composites. The effect of an oxygen inhibition layer on the shear bond strength of incrementally placed particulate filling composite layers was also evaluated. Four different restorative composites were selected: everX Posterior (a short-fiber-reinforced composite), Z250, SupremeXT, and Silorane. All composites were evaluated regarding the thickness of the oxygen inhibition layer and for shear bond strength. An equal amount of each composite was polymerized in air between two glass plates and the thickness of the oxygen inhibition layer was measured using a stereomicroscope. Cylindrical-shaped specimens were prepared for measurement of shear bond strength by placing incrementally two layers of the same composite material. Before applying the second composite layer, the first increment's bonding site was treated as follows: grinding with 1,000-grit silicon-carbide (SiC) abrasive paper, or treatment with ethanol or with water-spray. The inhibition depth was lowest (11.6 μm) for water-sprayed Silorane and greatest (22.9 μm) for the water-sprayed short-fiber-reinforced composite. The shear bond strength ranged from 5.8 MPa (ground Silorane) to 36.4 MPa (water-sprayed SupremeXT). The presence of an oxygen inhibition layer enhanced the interlayer shear bond strength of all investigated materials, but its absence resulted in cohesive and mixed failures only with the short-fiber-reinforced composite. Thus, more durable adhesion with short-fiber-reinforced composite is expected. © 2014 Eur J Oral Sci.

  9. Electron Scattering at Surfaces of Epitaxial Metal Layers

    Science.gov (United States)

    Chawla, Jasmeet Singh

    In the field of electron transport in metal films and wires, the 'size effect' refers to the increase in the resistivity of the films and wires as their critical dimensions (thickness of film, width and height of wires) approach or become less than the electron mean free path lambda, which is, for example, 39 nm for bulk copper at room temperature. This size-effect is currently of great concern to the semiconductor industry because the continued downscaling of feature sizes has already lead to Cu interconnect wires in this size effect regime, with a reported 2.5 times higher resistivity for 40 nm wide Cu wires than for bulk Cu. Silver is a possible alternate material for interconnect wires and titanium nitride is proposed as a gate metal in novel field-effect-transistors. Therefore, it is important to develop an understanding of how the growth, the surface morphology, and the microstructure of ultrathin (few nanometers) Cu, Ag and TiN layers affect their electrical properties. This dissertation aims to advance the scientific knowledge of electron scattering at surfaces (external surfaces and grain boundaries), that are, the primary reasons for the size-effect in metal conductors. The effect of surface and grain boundary scattering on the resistivity of Cu thin films and nanowires is separately quantified using (i) in situ transport measurements on single-crystal, atomically smooth Cu(001) layers, (ii) textured polycrystalline Cu(111) layers and patterned wires with independently varying grain size, thickness and line width, and (iii) in situ grown interfaces including Cu-Ta, Cu-MgO, Cu-vacuum and Cu-oxygen. In addition, the electron surface scattering is also measured in situ for single-crystal Ag(001), (111) twinned epitaxial Ag(001), and single-crystal TiN(001) layers. Cu(001), Ag(001), and TiN(001) layers with a minimum continuous thickness of 4, 3.5 and 1.8 nm, respectively, are grown by ultra-high vacuum magnetron sputter deposition on MgO(001) substrates with

  10. Superficial hardened layer of cut surface by turning

    Directory of Open Access Journals (Sweden)

    Croitoru Sorin Mihai

    2017-01-01

    Full Text Available One of research methods in metal cutting process is to measure hardness in the contact zone between cutting tool and workpiece. The objective of the performed research was to determine thickness and hardness of the superficial layer of cut surface due to cutting process, both orthogonal and complex cutting. The most important finding was that thickness of the superficial hardened layer is very thin under considered conditions, less than 0.01 … 0.02 mm. This research should be continued.

  11. Surface roughness effects on the hypersonic turbulent boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Berg, D.E.

    1977-09-01

    An experimental investigation of the response of a hypersonic turbulent boundary layer to a step change in surface roughness has been performed. The boundary layer on a flat nozzle wall of a Mach 6 wind tunnel was subjected to abrupt changes in surface roughness and its adjustment to the new surface conditions was examined. Both mean and fluctuating flow properties were acquired for smooth-to-rough and rough-to-smooth surface configurations. The boundary layer was found to respond gradually and to attain new equilibrium profiles, for both the mean and the fluctuating properties, some 10 to 25 delta downstream of the step change. Mean flow self-similarity was the first to establish itself, followed by the mass flux fluctuations, followed in turn by the total temperature fluctuations. Use of a modified Van Driest transformation resulted in good correlations of smooth and rough wall data in the form of the incompressible law of the wall. This is true even in the nonequilibrium vicinity of the step for small roughness heights. The present data are found to correlate well with previously published roughness effect data from low and high speed flows when the roughnesses are characterized by an equivalent sand grain roughness height.

  12. Boundary layer for non-newtonian fluids on curved surfaces

    International Nuclear Information System (INIS)

    Stenger, N.

    1981-04-01

    By using the basic equation of fluid motion (conservation of mass and momentum) the boundary layer parameters for a Non-Newtonian, incompressible and laminar fluid flow, has been evaluated. As a test, the flat plate boundary layer is first analized and afterwards, a case with pressure gradient, allowing separation, is studied. In the case of curved surfaces, the problem is first developed in general and afterwards particularized to a circular cylinder. Finally suction and slip in the flow interface are examined. The power law model is used to represent the stress strain relationship in Non-Newtonian flow. By varying the fluid exponent one can then, have an idea of how the Non-Newtonian behavior of the flow influences the parameters of the boundary layer. Two equations, in an appropriate coordinate system have been obtained after an order of magnitude analysis of the terms in the equations of motion is performed. (Author) [pt

  13. The studies of scale surface produced on outer diffusion layers

    Directory of Open Access Journals (Sweden)

    J. Augustyn-Pieniążek

    2011-04-01

    Full Text Available In this study at attempt was made to examine the scale formed on ferritic-austenitic duplex type steel subjected to previous thermochemical treatment. The treatment consisted in diffusion aluminising in a metallising mixture composed of Fe-Al powder. As an activator, ammonium chloride (NH4Cl added in an amount of 2 wt.% was used. Then, both the base material and samples with the diffusiondeposited surface layers were oxidised at 1000°C in the air. Thus formed scales were identified by light microscopy, SEM and X-ray phase analysis. The aim of the oxidation tests carried out under isothermal conditions was to compare the scale morphology when obtained on untreated substrate material and on the surface layers rich in aluminium.

  14. Combined surface acoustic wave and surface plasmon resonance measurement of collagen and fibrinogen layer physical properties

    Directory of Open Access Journals (Sweden)

    J.-M. Friedt

    2016-12-01

    Full Text Available We use an instrument combining optical (surface plasmon resonance and acoustic (Love mode surface acoustic wave device real-time measurements on a same surface for the identification of water content in collagen and fibrinogen protein layers. After calibration of the surface acoustic wave device sensitivity by copper electrodeposition and surfactant adsorption, the bound mass and its physical properties – density and optical index – are extracted from the complementary measurement techniques and lead to thickness and water ratio values compatible with the observed signal shifts. Such results are especially usefully for protein layers with a high water content as shown here for collagen on an hydrophobic surface. We obtain the following results: collagen layers include 70±20% water and are 16±3 to 19±3 nm thick for bulk concentrations ranging from 30 to 300 μg/ml. Fibrinogen layers include 50±10% water for layer thicknesses in the 6±1.5 to 13±2 nm range when the bulk concentration is in the 46 to 460 μg/ml range. Keywords: surface acoustic wave, surface plasmon resonance, collagen, fibrinogen, density, thickness

  15. Modeling Turbulence Generation in the Atmospheric Surface and Boundary Layers

    Science.gov (United States)

    2015-10-01

    ZT ). The initial acceleration of the rising buoyant air will be a = g∆T/TA. This is simply Archimedes ’ principle applied to the buoyant air. The... applications . 1 Various rules are employed to model C2n in the surface layer, but a key question is how to extend this estimation technique into the lower...in terms of wind turbulence the structure of the fluctuations produces a Reynolds stress tensor whose principle axes are not equal, meaning that at the

  16. Surface layer softing in mechanically polished molybdenum monocrystals

    International Nuclear Information System (INIS)

    Ivashchenko, R.K.; Kostyuchenko, V.G.; Lotsko, D.V.; Lukinov, I.V.; Mil'man, Yu.V.; Novikov, G.A.

    1990-01-01

    Softening of the surface layer together with growth of dislocation density is found in molybdenum single crystals mechanically polished with diamond suspension in water solution of CuSO 4 . The penetration of small amount of copper into molybdenum is observed by SIMS. A supposition has been made about molybdenum solid solution softening influenced by copper penetrating into molybdenum by means of a dynamic dislocation mechanism

  17. Surface alloys as interfacial layers between quasicrystalline and periodic materials

    Science.gov (United States)

    Duguet, T.; Ledieu, J.; Dubois, J. M.; Fournée, V.

    2008-08-01

    Low adhesion with normal metals is an intrinsic property of many quasicrystalline surfaces. Although this property could be useful to develop low friction or non-stick coatings, it is also responsible for the poor adhesion of quasicrystalline coatings on metal substrates. Here we investigate the possibility of using complex metallic surface alloys as interface layers to enhance the adhesion between quasicrystals and simple metal substrates. We first review some examples where such complex phases are formed as an overlayer. Then we study the formation of such surface alloys in a controlled way by annealing a thin film deposited on a quasicrystalline substrate. We demonstrate that a coherent buffer layer consisting of the γ-Al4Cu9 approximant can be grown between pure Al and the i-Al-Cu-Fe quasicrystal. The interfacial relationships between the different layers are defined by [111]_{\\mathrm {Al}}\\parallel [110]_{\\mathrm {Al_4Cu_9}}\\parallel [5\\mathrm {f}]_{i\\mbox {-}\\mathrm {Al\\mbox {--}Cu \\mbox {--}Fe}} .

  18. Surface alloys as interfacial layers between quasicrystalline and periodic materials

    Energy Technology Data Exchange (ETDEWEB)

    Duguet, T; Ledieu, J; Dubois, J M; Fournee, V [Laboratoire de Science et Genie des Materiaux et de Metallurgie, UMR 7584 CNRS-Nancy Universite, Ecole des Mines de Nancy, Parc de Saurupt, F-54042 Nancy (France)], E-mail: fournee@lsg2m.org

    2008-08-06

    Low adhesion with normal metals is an intrinsic property of many quasicrystalline surfaces. Although this property could be useful to develop low friction or non-stick coatings, it is also responsible for the poor adhesion of quasicrystalline coatings on metal substrates. Here we investigate the possibility of using complex metallic surface alloys as interface layers to enhance the adhesion between quasicrystals and simple metal substrates. We first review some examples where such complex phases are formed as an overlayer. Then we study the formation of such surface alloys in a controlled way by annealing a thin film deposited on a quasicrystalline substrate. We demonstrate that a coherent buffer layer consisting of the {gamma}-Al{sub 4}Cu{sub 9} approximant can be grown between pure Al and the i-Al-Cu-Fe quasicrystal. The interfacial relationships between the different layers are defined by [111]{sub Al} parallel [110]{sub Al4Cu9} parallel [5f]{sub i-Al-}C{sub u-Fe}.

  19. Virtual ellipsometry on layered micro-facet surfaces.

    Science.gov (United States)

    Wang, Chi; Wilkie, Alexander; Harcuba, Petr; Novosad, Lukas

    2017-09-18

    Microfacet-based BRDF models are a common tool to describe light scattering from glossy surfaces. Apart from their wide-ranging applications in optics, such models also play a significant role in computer graphics for photorealistic rendering purposes. In this paper, we mainly investigate the computer graphics aspect of this technology, and present a polarisation-aware brute force simulation of light interaction with both single and multiple layered micro-facet surfaces. Such surface models are commonly used in computer graphics, but the resulting BRDF is ultimately often only approximated. Recently, there has been work to try to make these approximations more accurate, and to better understand the behaviour of existing analytical models. However, these brute force verification attempts still emitted the polarisation state of light and, as we found out, this renders them prone to mis-estimating the shape of the resulting BRDF lobe for some particular material types, such as smooth layered dielectric surfaces. For these materials, non-polarising computations can mis-estimate some areas of the resulting BRDF shape by up to 23%. But we also identified some other material types, such as dielectric layers over rough conductors, for which the difference turned out to be almost negligible. The main contribution of our work is to clearly demonstrate that the effect of polarisation is important for accurate simulation of certain material types, and that there are also other common materials for which it can apparently be ignored. As this required a BRDF simulator that we could rely on, a secondary contribution is that we went to considerable lengths to validate our software. We compare it against a state-of-art model from graphics, a library from optics, and also against ellipsometric measurements of real surface samples.

  20. Effect of impurities in the description of surface nanobubbles: Role of nonidealities in the surface layer

    NARCIS (Netherlands)

    Das, S.

    2011-01-01

    In a recent study [ S. Das, J. H. Snoeijer and D. Lohse Phys. Rev. E 82 056310 (2010)], we provided quantitative demonstration of the conjecture [ W. A. Ducker Langmuir 25 8907 (2009)] that the presence of impurities at the surface layer (or the air-water interface) of surface nanobubbles can

  1. Amorphous surface layers in Ti-implanted Fe

    Energy Technology Data Exchange (ETDEWEB)

    Knapp, J.A.; Follstaedt, D.M.; Picraux, S.T.

    1979-01-01

    Implanting Ti into high-purity Fe results in an amorphous surface layer which is composed of not only Fe and Ti, but also C. Implantations were carried out at room temperature over the energy range 90 to 190 keV and fluence range 1 to 2 x 10/sup 16/ at/cm/sup 2/. The Ti-implanted Fe system has been characterized using transmission electron microscopy (TEM), ion backscattering and channeling analysis, and (d,p) nuclear reaction analysis. The amorphous layer was observed to form at the surface and grow inward with increasing Ti fluence. For an implant of 1 x 10/sup 17/ Ti/cm/sup 2/ at 180 keV the layer thickness was 150 A, while the measured range of the implanted Ti was approx. 550 A. This difference is due to the incorporation of C into the amorphous alloy by C being deposited on the surface during implantation and subsequently diffusing into the solid. Our results indicate that C is an essential constituent of the amorphous phase for Ti concentrations less than or equal to 10 at. %. For the 1 x 10/sup 17/ Ti/cm/sup 2/ implant, the concentration of C in the amorphous phase was approx. 25 at. %, while that of Ti was only approx. 3 at. %. A higher fluence implant of 2 x 10/sup 17/ Ti/cm/sup 2/ produced an amorphous layer with a lower C concentration of approx. 10 at. % and a Ti concentration of approx. 20 at. %.

  2. Application of various surface passivation layers in solar cells

    International Nuclear Information System (INIS)

    Lee, Ji Youn; Lee, Soo Hong

    2004-01-01

    In this work, we have used different techniques for surface passivation: conventional thermal oxidation (CTO), rapid thermal oxidation (RTO), and plasma-enhanced chemical vapour deposition (PECVD). The surface passivation qualities of eight different single and combined double layers have been investigated both on phosphorus non-diffused p-type Float Zone (FZ) silicon wafers and on diffused emitters (100 Ω/□ and 40 Ω/□). CTO/SiN 1 passivates very well not only on a non-diffused surface (τ eff = 1361 μs) but also on an emitter (τ eff = 414 μs). However, we concluded that RTO/SiN 1 and RTO/SiN 2 stacks were more suitable than CTO/SiN stacks for surface passivation in solar cells since those stacks had relatively good passivation qualities and suitable optical reflections. RTO/SiN 1 for rear-surface passivation and RTO/SiN 2 for front-surface passivation were applied to the fabrication of solar cells. We achieved efficiencies of 18.5 % and 18.8 % on 0.5 Ω-cm (FZ) silicon with planar and textured front surfaces, respectively. An excellent open circuit voltage (V oc ) of 675.6 mV was obtained for the planar cell.

  3. Influence of Surface Energy Effects on Elastic Fields of a Layered Elastic Medium under Surface Loading

    Directory of Open Access Journals (Sweden)

    Supakorn Tirapat

    2017-01-01

    Full Text Available This paper presents the analysis of a layered elastic half space under the action of axisymmetric surface loading and the influence of the surface energy effects. The boundary value problems for the bulk and the surface are formulated based on classical linear elasticity and a complete Gurtin-Murdoch constitutive relation. An analytical technique using Love’s representation and the Hankel integral transform is employed to derive an integral-form solution for both displacement and stress fields. An efficient numerical quadrature is then applied to accurately evaluate all involved integrals. Selected numerical results are presented to portray the influence of various parameters on elastic fields. Numerical results indicate that the surface stress displays a significant influence on both displacement and stress fields. It is also found that the layered half space becomes stiffer with the presence of surface stresses. In addition, unlike the classical elasticity solution, size-dependent behavior of elastic fields is noted. The present analytical solutions provide fundamental understanding of the influence of surface energy on layered elastic materials. It can also be used as a benchmark solution for the development of numerical techniques such as FEM and BEM, for analysis of more complex problems involving a layered medium under the influence of surface energy effects.

  4. Durable superhydrophobic surfaces made by intensely connecting a bipolar top layer to the substrate with a middle connecting layer.

    Science.gov (United States)

    Zhi, Jinghui; Zhang, Li-Zhi

    2017-08-30

    This study reported a simple fabrication method for a durable superhydrophobic surface. The superhydrophobic top layer of the durable superhydrophobic surface was connected intensely to the substrate through a middle connecting layer. Glycidoxypropyltrimethoxysilane (KH-560) after hydrolysis was used to obtain a hydrophilic middle connecting layer. It could be adhered to the hydrophilic substrate by covalent bonds. Ring-open reaction with octadecylamine let the KH-560 middle layer form a net-like structure. The net-like sturcture would then encompass and station the silica particles that were used to form the coarse micro structures, intensely to increase the durability. The top hydrophobic layer with nano-structures was formed on the KH-560 middle layer. It was obtained by a bipolar nano-silica solution modified by hexamethyldisilazane (HMDS). This layer was connected to the middle layer intensely by the polar Si hydroxy groups, while the non-polar methyl groups on the surface, accompanied by the micro and nano structures, made the surface rather hydrophobic. The covalently interfacial interactions between the substrate and the middle layer, and between the middle layer and the top layer, strengthened the durability of the superhydrophobic surface. The abrasion test results showed that the superhydrophobic surface could bear 180 abrasion cycles on 1200 CW sandpaper under 2 kPa applied pressure.

  5. Nanoscale Structuring of Surfaces by Using Atomic Layer Deposition.

    Science.gov (United States)

    Sobel, Nicolas; Hess, Christian

    2015-12-07

    Controlled structuring of surfaces is interesting for a wide variety of areas, including microelectronic device fabrication, optical devices, bio(sensing), (electro-, photo)catalysis, batteries, solar cells, fuel cells, and sorption. A unique feature of atomic layer deposition (ALD) is the possibility to form conformal uniform coatings on arbitrarily shaped materials with controlled atomic-scale thickness. In this Minireview, we discuss the potential of ALD for the nanoscale structuring of surfaces, highlighting its versatile application to structuring both planar substrates and powder materials. Recent progress in the application of ALD to porous substrates has even made the nanoscale structuring of high-surface-area materials now feasible, thereby enabling novel applications, such as those in the fields of catalysis and alternative energy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Surface energy absorbing layers produced by ion implantation

    International Nuclear Information System (INIS)

    Gurarie, V.N.

    1997-01-01

    Single crystals of magnesia have been ion implanted with 80 keV Si and Cr ions at variable doses and then subjected to testing in a shock plasma. The peak surface temperature has been calibrated by measuring the size and temperature deformation of the fragments formed by multiple microcracking during thermal shock. the crack density curves for MgO crystals demonstrate that in a wide range of thermal shock intensity the ion implanted crystals develop a system of microcracks of a considerably higher density than the unimplanted ones. The high density of cracks nucleated in the ion implanted samples results in the formation of a surface energy absorbing layer which effectively absorbs elastic strain energy induced by thermal shock. As a consequence the depth of crack penetration in the layer and hence the degree of fracture damage are decreased. the results indicate that a Si implant decreases the temperature threshold of cracking and simultaneously increases the crack density in MgO crystals. However, in MgO crystals implanted with Cr a substantial increase in the crack density is achieved without a noticeable decrease in the temperature threshold of fracture. This effect is interpreted in terms of different Cr and Si implantation conditions and damage. The mechanical properties of the energy-absorbing layer and the relation to implantation-induced lattice damage are discussed. 11 refs., 4 figs

  7. Error Detection in ESL Teaching

    OpenAIRE

    Rogoveanu Raluca

    2011-01-01

    This study investigates the role of error correction in the larger paradigm of ESL teaching and learning. It conceptualizes error as an inevitable variable in the process of learning and as a frequently occurring element in written and oral discourses of ESL learners. It also identifies specific strategies in which error can be detected and corrected and makes reference to various theoretical trends and their approach to error correction, as well as to the relation between language instructor...

  8. A novel surface cleaning method for chemical removal of fouling lead layer from chromium surfaces

    Science.gov (United States)

    Gholivand, Kh.; Khosravi, M.; Hosseini, S. G.; Fathollahi, M.

    2010-10-01

    Most products especially metallic surfaces require cleaning treatment to remove surface contaminations that remain after processing or usage. Lead fouling is a general problem which arises from lead fouling on the chromium surfaces of bores and other interior parts of systems which have interaction with metallic lead in high temperatures and pressures. In this study, a novel chemical solution was introduced as a cleaner reagent for removing metallic lead pollution, as a fouling metal, from chromium surfaces. The cleaner aqueous solution contains hydrogen peroxide (H 2O 2) as oxidizing agent of lead layer on the chromium surface and acetic acid (CH 3COOH) as chelating agent of lead ions. The effect of some experimental parameters such as acetic acid concentration, hydrogen peroxide concentration and temperature of the cleaner solution during the operation on the efficiency of lead cleaning procedure was investigated. The results of scanning electron microscopy (SEM) showed that using this procedure, the lead pollution layer could be completely removed from real chromium surfaces without corrosion of the original surface. Finally, the optimum conditions for the complete and fast removing of lead pollution layer from chromium surfaces were proposed. The experimental results showed that at the optimum condition (acetic acid concentration 28% (V/V), hydrogen peroxide 8% (V/V) and temperature 35 °C), only 15-min time is needed for complete removal of 3 g fouling lead from a chromium surface.

  9. Hierarchical Composite Membranes with Robust Omniphobic Surface Using Layer-By-Layer Assembly Technique

    KAUST Repository

    Woo, Yun Chul

    2018-01-17

    In this study, composite membranes were fabricated via layer-by-layer (LBL) assembly of negatively-charged silica aerogel (SiA) and 1H, 1H, 2H, 2H – Perfluorodecyltriethoxysilane (FTCS) on a polyvinylidene fluoride phase inversion membrane, and interconnecting them with positively-charged poly(diallyldimethylammonium chloride) (PDDA) via electrostatic interaction. The results showed that the PDDA-SiA-FTCS coated membrane had significantly enhanced the membrane structure and properties. New trifluoromethyl and tetrafluoroethylene bonds appeared at the surface of the coated membrane, which led to lower surface free energy of the composite membrane. Additionally, the LBL membrane showed increased surface roughness. The improved structure and property gave the LBL membrane an omniphobic property, as indicated by its good wetting resistance. The membrane performed a stable air gap membrane distillation (AGMD) flux of 11.22 L/m2h with very high salt rejection using reverse osmosis brine from coal seam gas produced water as feed with the addition of up to 0.5 mM SDS solution. This performance was much better compared to those of the neat membrane. The present study suggests that the enhanced membrane properties with good omniphobicity via LBL assembly make the porous membranes suitable for long-term AGMD operation with stable permeation flux when treating challenging saline wastewater containing low surface tension organic contaminants.

  10. Moored surface buoy observations of the diurnal warm layer

    KAUST Repository

    Prytherch, J.

    2013-09-01

    An extensive data set is used to examine the dynamics of diurnal warming in the upper ocean. The data set comprises more than 4700 days of measurements at five sites in the tropics and subtropics, obtained from surface moorings equipped to make comprehensive meteorological, incoming solar and infrared radiation, and high-resolution subsurface temperature (and, in some cases, velocity) measurements. The observations, which include surface warmings of up to 3.4°C, are compared with a selection of existing models of the diurnal warm layer (DWL). A simple one-layer physical model is shown to give a reasonable estimate of both the magnitude of diurnal surface warming (model-observation correlation 0.88) and the structure and temporal evolution of the DWL. Novel observations of velocity shear obtained during 346 days at one site, incorporating high-resolution (1 m) upper ocean (5-15 m) acoustic Doppler current profile measurements, are also shown to be in reasonable agreement with estimates from the physical model (daily maximum shear model-observation correlation 0.77). Physics-based improvements to the one-layer model (incorporation of rotation and freshwater terms) are discussed, though they do not provide significant improvements against the observations reported here. The simplicity and limitations of the physical model are used to discuss DWL dynamics. The physical model is shown to give better model performance under the range of forcing conditions experienced across the five sites than the more empirical models. ©2013. American Geophysical Union. All Rights Reserved.

  11. Boundary layer flow of nanofluid over an exponentially stretching surface

    Science.gov (United States)

    Nadeem, Sohail; Lee, Changhoon

    2012-01-01

    The steady boundary layer flow of nanofluid over an exponential stretching surface is investigated analytically. The transport equations include the effects of Brownian motion parameter and thermophoresis parameter. The highly nonlinear coupled partial differential equations are simplified with the help of suitable similarity transformations. The reduced equations are then solved analytically with the help of homotopy analysis method (HAM). The convergence of HAM solutions are obtained by plotting h-curve. The expressions for velocity, temperature and nanoparticle volume fraction are computed for some values of the parameters namely, suction injection parameter α, Lewis number Le, the Brownian motion parameter Nb and thermophoresis parameter Nt.

  12. Boundary layer flow of nanofluid over an exponentially stretching surface.

    Science.gov (United States)

    Nadeem, Sohail; Lee, Changhoon

    2012-01-30

    The steady boundary layer flow of nanofluid over an exponential stretching surface is investigated analytically. The transport equations include the effects of Brownian motion parameter and thermophoresis parameter. The highly nonlinear coupled partial differential equations are simplified with the help of suitable similarity transformations. The reduced equations are then solved analytically with the help of homotopy analysis method (HAM). The convergence of HAM solutions are obtained by plotting h-curve. The expressions for velocity, temperature and nanoparticle volume fraction are computed for some values of the parameters namely, suction injection parameter α, Lewis number Le, the Brownian motion parameter Nb and thermophoresis parameter Nt.

  13. Monodisperse gold nanoparticles formed on bacterial crystalline surface layers (S-layers) by electroless deposition

    Energy Technology Data Exchange (ETDEWEB)

    Dieluweit, S. [Center for Nanobiotechnology, University of Natural Resources and Applied Life Sciences (BOKU), Gregor Mendel-Strasse 33, A-1180 Vienna (Austria); Pum, D. [Center for Nanobiotechnology, University of Natural Resources and Applied Life Sciences (BOKU), Gregor Mendel-Strasse 33, A-1180 Vienna (Austria); Sleytr, U.B. [Center for Nanobiotechnology, University of Natural Resources and Applied Life Sciences (BOKU), Gregor Mendel-Strasse 33, A-1180 Vienna (Austria); Kautek, W. [Department for Physical Chemistry, University of Vienna, Waehringer Strasse 42, A-1090 Vienna (Austria)]. E-mail: wolfgang.kautek@univie.ac.at

    2005-12-15

    The fabrication of patterned arrays of nanoparticles whose electronic, optical and magnetic properties will find technological applications, such as ultra-high-density memories, is currently one of the most important objectives of inorganic material research. In this study, the in situ electroless nucleation of ordered two-dimensional arrays of gold nanoparticles (5 nm in size) by using bacterial S-layers as molecular templates and their characterization by small spot X-ray photoelectron emission spectroscopy (XPS) is presented. This yielded the elemental composition of the nanoclusters, which consisted of almost entirely elemental gold, and possible side reactions on the cluster and protein surface. The preferential deposition of the gold nanoparticles on the S-layer suggests that topography and functional groups are important for superlattice formation.

  14. Nanofilms of hyaluronan/chitosan assembled layer-by-layer: An antibacterial surface for Xylella fastidiosa.

    Science.gov (United States)

    Hernández-Montelongo, Jacobo; Nascimento, Vicente F; Murillo, Duber; Taketa, Thiago B; Sahoo, Prasana; de Souza, Alessandra A; Beppu, Marisa M; Cotta, Monica A

    2016-01-20

    In this work, nanofilms of hyaluronan/chitosan (HA/CHI) assembled layer by layer were synthesized; their application as a potential antimicrobial material was demonstrated for the phytopathogen Xylella fastidiosa, a gram-negative bacterium, here used as a model. For the synthesis, the influence of pH and ionic strength of these natural polymer stem-solutions on final characteristics of the HA/CHI nanofilms was studied in detail. The antibacterial effect was evaluated using widefield fluorescence microscopy. These results were correlated with the chemical properties of the nanofilms, studied by FTIR and Raman spectroscopy, as well as with their morphology and surface properties characterized using SEM and AFM. The present findings can be extended to design and optimize HA/CHI nanofilms with enhanced antimicrobial behavior for other type of phytopathogenic gram-negative bacteria species, such as Xanthomonas citri, Xanthomas campestri and Ralstonia solanacearum. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Fluency First: Reversing the Traditional ESL Sequence.

    Science.gov (United States)

    MacGowan-Gilhooly, Adele

    1991-01-01

    Describes an ESL department's whole language approach to writing and reading, replacing its traditional grammar-based ESL instructional sequence. Reports the positive quantitative and qualitative results of the first three years of using the new approach. (KEH)

  16. Atomic and molecular layer activation of dielectric surfaces

    Science.gov (United States)

    Senkevich, John Joseph

    Strong interaction between the material deposit and substrate is critical to stable deposits and interfaces. The work presented here focuses on the surface activation of dielectric surfaces and oxidized metal surfaces to promote the chemisorption of palladium (II) hexafluoroacetylacetonate (PdII (hfac)2). The goal is to develop reliable, robust metallization protocols, which enable strong interactions between the metal and substrate. SiO2, air exposed Ta, Trikon, and SiLK were activated with sulfur or phosphorus. Two types of activations were developed; one based on self-assembled chemistry, and the other a plasma-assisted process. Activation of the surface using self-assembly techniques was carried out using mercaptan-terminated silane and tetrasulfide silane. The resulting films were characterized by variable angle spectroscopic ellipsometry, contact angle goniometry, and X-ray photoelectron spectroscopy. Tetrasulfide silane sources films exhibit self-limiting behavior, even in the presence of water vapor; whereas mercaptan-terminated silane sourced films tend to be thicker. The surface activations using atomic layers of sulfur and phosphorus were carried out in a rf plasma chamber using hydrogen sulfide and phosphine sources, respectively. The activations were studied as functions of rf power, system pressure, and substrate material. Results show that higher rf powers and lower system pressures promote greater surface coverages by sulfur with a reduced oxidation state. The activated dielectrics show evidence of PdII(hfac)2 chemisorption, in contrast to non-activated surfaces. The binding energy shift of the Pd3d 5/2 XPS peak towards elemental Pd provides evidence for the dissociative chemisorption of PdII(hfac)2. The extent of dissociation depends on the substrate temperature and the activation method used. The conclusions of the work presented here have implications for metallization using highly polarizable transition metals. Specifically, it can be applied to

  17. A numerical model for chemical reaction on slag layer surface and slag layer behavior in entrained-flow gasifier

    Directory of Open Access Journals (Sweden)

    Liu Sheng

    2013-01-01

    Full Text Available The paper concerns with slag layer accumulation, chemical reaction on slag layer surface, and slag layer flow, heat and mass transfer on the wall of entrained-flow coal gasifier. A slag layer model is developed to simulate slag layer behaviors in the coal gasifier. This 3-D model can predict temperature, slag particle disposition rate, disposition particle composition, and syngas distribution in the gasifier hearth. The model is used to evaluate the effects of O2/coal ratio on slag layer behaviors.

  18. New surface layers with low rolling resistance tested in Denmark

    DEFF Research Database (Denmark)

    Pettinari, Matteo; Schmidt, Bjarne; Jensen, Bjarne Bo

    2014-01-01

    The project ‘CO2 emission reduction by exploitation of rolling resistance modeling of pavements’ (COOEE) was started in 2011 to establish a scientific background for development of novel pavement types and asset management solutions that minimize the rolling resistance for cars and trucks......, the purpose being to reduce CO2 emission from the transport sector. In summer 2012, three different test sections were constructed on a highway located near Vordingborg, Denmark, in order to verify the respective Rolling Resistances; the main purpose was to develop and design new surface layers with reduced...... Rolling Resistance coefficient that could improve energy efficiency of the roads. In particular, two new types of Split Mastic Asphalt (SMA) were developed and compared to a reference one; both mixtures have a relatively small maximum grain-size, 6 mm and 8 mm, respectively. Surface measurements...

  19. Formation of nanocrystalline surface layers in various metallic materials by near surface severe plastic deformation

    Directory of Open Access Journals (Sweden)

    Masahide Sato, Nobuhiro Tsuji, Yoritoshi Minamino and Yuichiro Koizumi

    2004-01-01

    Full Text Available The surface of the various kinds of metallic materials sheets were severely deformed by wire-brushing at ambient temperature to achieve nanocrystalline surface layer. The surface layers of the metallic materials developed by the near surface severe plastic deformation (NS-SPD were characterized by means of TEM. Nearly equiaxed nanocrystals with grain sizes ranging from 30 to 200 nm were observed in the near surface regions of all the severely scratched metallic materials, which are Ti-added ultra-low carbon interstitial free steel, austenitic stainless steel (SUS304, 99.99 wt.%Al, commercial purity aluminum (A1050 and A1100, Al–Mg alloy (A5083, Al-4 wt.%Cu alloy, OFHC-Cu (C1020, Cu–Zn alloy (C2600 and Pb-1.5%Sn alloy. In case of the 1050-H24 aluminum, the depth of the surface nanocrystalline layer was about 15 μm. It was clarified that wire-brushing is an effective way of NS-SPD, and surface nanocrystallization can be easily achieved in most of metallic materials.

  20. Surface layer conditions of the atmosphere over western Bay of Bengal during Monex

    Digital Repository Service at National Institute of Oceanography (India)

    Anto, A.F.; Rao, L.V.G.; Somayajulu, Y.K.

    Based on surface meteorological data and wave data collected from 2 stations in the western Bay of Bengal in July 1979, surface layer (SL) conditions of the atmosphere for different situations of surface circulations and the associated sea surface...

  1. Working toward Literacy in Correctional Education ESL

    Science.gov (United States)

    Gardner, Susanne

    2014-01-01

    Correctional Education English as a Second Language (ESL) literacy programs vary from state to state, region to region. Some states enroll their correctional ESL students in adult basic education (ABE) classes; other states have separate classes and programs. At the Maryland Correctional Institution in Jessup, the ESL class is a self-contained…

  2. Crystalline Bacterial Surface Layer (S-Layer) Opens Golden Opportunities for Nanobiotechnology in Textiles.

    Science.gov (United States)

    Asadi, Narges; Chand, Nima; Rassa, Mehdi

    2015-12-01

    This study focuses on the successful recrystallization of bacterial S-layer arrays of the Lactobacillus acidophilus ATCC 4356 at textile surfaces to create a novel method and material. Optimum bacterial growth was obtained at approximately 45 °C, pH 5.0, and 14 h pi. The cells were resuspended in guanidine hydrochloride and the 43 kDa S-protein was dialyzed and purified. The optimum reassembly on the polypropylene fabric surface in terms of scanning electron microscopy (SEM), reflectance, and uniformity (spectrophotometry) was obtained at 30 °C, pH 5.0 for 30 minutes in the presence of 2 gr/l (liquor ratio; 1:40) of the S-protein. Overall, our data showed that the functional aspects and specialty applications of the fabric would be very attractive for the textile and related sciences, and result in advanced technical textiles.

  3. Surface Modification of Dental Titanium Implant by Layer-by-Layer Electrostatic Self-Assembly

    Directory of Open Access Journals (Sweden)

    Quan Shi

    2017-08-01

    Full Text Available In vivo implants that are composed of titanium and titanium alloys as raw materials are widely used in the fields of biology and medicine. In the field of dental medicine, titanium is considered to be an ideal dental implant material. Good osseointegration and soft tissue closure are the foundation for the success of dental implants. Therefore, the enhancement of the osseointegration and antibacterial abilities of titanium and its alloys has been the focus of much research. With its many advantages, layer-by-layer (LbL assembly is a self-assembly technique that is used to develop multilayer films based on complementary interactions between differently charged polyelectrolytes. The LbL approach provides new methods and applications for the surface modification of dental titanium implant. In this review, the application of the LbL technique to surface modification of titanium including promoting osteogenesis and osseointegration, promoting the formation and healing of soft tissues, improving the antibacterial properties of titanium implant, achieving local drug delivery and sustained release is summarized.

  4. 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.

  5. Controlling molecular deposition and layer structure with supramolecular surface assemblies

    Science.gov (United States)

    Theobald, James A.; Oxtoby, Neil S.; Phillips, Michael A.; Champness, Neil R.; Beton, Peter H.

    2003-08-01

    Selective non-covalent interactions have been widely exploited in solution-based chemistry to direct the assembly of molecules into nanometre-sized functional structures such as capsules, switches and prototype machines. More recently, the concepts of supramolecular organization have also been applied to two-dimensional assemblies on surfaces stabilized by hydrogen bonding, dipolar coupling or metal co-ordination. Structures realized to date include isolated rows, clusters and extended networks, as well as more complex multi-component arrangements. Another approach to controlling surface structures uses adsorbed molecular monolayers to create preferential binding sites that accommodate individual target molecules. Here we combine these approaches, by using hydrogen bonding to guide the assembly of two types of molecules into a two-dimensional open honeycomb network that then controls and templates new surface phases formed by subsequently deposited fullerene molecules. We find that the open network acts as a two-dimensional array of large pores of sufficient capacity to accommodate several large guest molecules, with the network itself also serving as a template for the formation of a fullerene layer.

  6. Measurement of atmospheric surface layer turbulence using unmanned aerial vehicles

    Science.gov (United States)

    Bailey, Sean; Canter, Caleb

    2017-11-01

    We describe measurements of the turbulence within the atmospheric surface layer using highly instrumented and autonomous unmanned aerial vehicles (UAVs). Results from the CLOUDMAP measurement campaign in Stillwater Oklahoma are presented including turbulence statistics measured during the transition from stably stratified to convective conditions. The measurements were made using pre-fabricated fixed-wing remote-control aircraft adapted to fly autonomously and carry multi-hole pressure probes, pressure, temperature and humidity sensors. Two aircraft were flown simultaneously, with one flying a flight path intended to profile the boundary layer up to 100 m and the other flying at a constant fixed altitude of 50 m. The evolution of various turbulent statistics was determined from these flights, including Reynolds stresses, correlations, spectra and structure functions. These results were compared to those measured by a sonic anemometer located on a 7.5 m tower. This work was supported by the National Science Foundation through Grant #CBET-1351411 and by National Science Foundation award #1539070, Collaboration Leading Operational UAS Development for Meteorology and Atmospheric Physics (CLOUDMAP).

  7. Hygrothermal analysis of surface layers of historical masonry

    Science.gov (United States)

    Kočí, Václav; Maděra, Jiří; Keppert, Martin; Černý, Robert

    2017-11-01

    The paper deals with the hygrothermal analysis of surface layers of historical masonry. Solid brick provided with a traditional and two modified lime-based plasters is studied. The heat and moisture transport in the envelope is induced by an exposure of the wall from the exterior side to dynamic climatic conditions of Olomouc, Czech Republic. The transport processes are described using diffusion type of mathematical model based on experimentally determined material properties. The computational results indicate that hygric transport and accumulation properties of exterior plasters affect the hygrothermal performance of the underlying solid brick in a very significant way, being able to regulate the amount of transported moisture. The modified lime plasters are not found generally superior to the traditional lime plasters in that respect. Therefore, their suitability for historical masonry should be assessed case by case, with a particular attention to the climatic conditions and to the properties of the load bearing structure.

  8. Thin hydroxyapatite surface layers on titanium produced by ion implantation

    CERN Document Server

    Baumann, H; Bilger, G; Jones, D; Symietz, I

    2002-01-01

    In medicine metallic implants are widely used as hip replacement protheses or artificial teeth. The biocompatibility is in all cases the most important requirement. Hydroxyapatite (HAp) is frequently used as coating on metallic implants because of its high acceptance by the human body. In this paper a process is described by which a HAp surface layer is produced by ion implantation with a continuous transition to the bulk material. Calcium and phosphorus ions are successively implanted into titanium under different vacuum conditions by backfilling oxygen into the implantation chamber. Afterwards the implanted samples are thermally treated. The elemental composition inside the implanted region was determined by nuclear analysis methods as (alpha,alpha) backscattering and the resonant nuclear reaction sup 1 H( sup 1 sup 5 N,alpha gamma) sup 1 sup 2 C. The results of X-ray photoelectron spectroscopy indicate the formation of HAp. In addition a first biocompatibility test was performed to compare the growing of m...

  9. Averaging of diffusing contaminant concentrations in atmosphere surface layer

    International Nuclear Information System (INIS)

    Ivanov, E.A.; Ramzina, T.V.

    1985-01-01

    Calculations permitting to average concentration fields of diffusing radioactive contaminant coming from the NPP exhaust stack in the atmospheric surface layer are given. Formulae of contaminant concentration field calculation are presented; it depends on the average wind direction value (THETA) for time(T) and stability of this direction (σsub(tgTHETA) or σsub(THETA)). Probability of wind direction deviation from the average value for time T is satisfactory described by the Gauss law. With instability increase in the atmosphere σ increases, when wind velocity increasing the values of σ decreases for all types of temperature gradients. Nonuniformity of σ value dependence on averaging time T is underlined, that requires accurate choice of σsub(tgTHETA) and σsub(THETA) parameters in calculations

  10. Large-deformation analysis of the elastic recoil of fibre layers in a Brinkman medium with application to the endothelial glycocalyx

    NARCIS (Netherlands)

    Han, Y. F.; Weinbaum, S.; Spaan, J. A. E.; Vink, H.

    2006-01-01

    There is wide interest in the role of the endothelial surface layer (ESL) in transmitting blood shear stress to the intracellular cytoskeleton of the endothelial cell. However, very little is known about the mechanical properties of the glycocalyx or the flexural rigidity of the core proteins that

  11. ESL intermediate/advanced writing

    CERN Document Server

    Munoz Page, Mary Ellen; Jaskiewicz, Mary

    2011-01-01

    Master ESL (English as a Second Language) Writing with the study guide designed for non-native speakers of English. Skill-building lessons relevant to today's topics help ESL students write complete sentences, paragraphs, and even multi-paragraph essays. It's perfect for classroom use or self-guided writing preparation.DETAILS- Intermediate drills for improving skills with parallel structure, mood, correct shifting errors & dangling participles- Advanced essay drills focusing on narrative, descriptive, process, reaction, comparison and contrast- Superb preparation for students taking the TOEFL

  12. Water Surface Ripples Generated by the Turbulent Boundary Layer of a Surface-Piercing Moving Wall

    Science.gov (United States)

    Washuta, N.; Masnadi, N.; Duncan, J. H.

    2014-11-01

    Free surface ripples created by subsurface turbulence along a surface-piercing moving wall are studied experimentally. In this experiment, a meter-wide stainless steel belt travels horizontally in a loop around two rollers with vertically oriented axes, which are separated by 7.5 meters. One of the two 7.5-m-long belt sections between the rollers is in contact with the water in a large open-surface water tank and the water level is adjusted so that the top of the belt pierces the water free surface. The belt is launched from rest with a 3 g acceleration in order to quickly reach a steady state velocity. This belt motion creates a temporally evolving boundary layer analogous to the spatially evolving boundary layer created along the side of a ship hull moving at the belt velocity, with a length equivalent to the length of belt that has passed the measurement region. The water surface ripples generated by the subsurface turbulence are measured in a plane normal to the belt using a cinematic LIF technique. It is found that the overall RMS surface fluctuations increase linearly with belt speed and that the spatial distributions of the fluctuations show a sharp increase near the wall. The support of the Office of Naval Research is gratefully acknowledged.

  13. Regulation and function of endothelial glycocalyx layer in vascular diseases.

    Science.gov (United States)

    Sieve, Irina; Münster-Kühnel, Anja K; Hilfiker-Kleiner, Denise

    2018-01-01

    In the vascular system, the endothelial surface layer (ESL) as the inner surface of blood vessels affects mechanotransduction, vascular permeability, rheology, thrombogenesis, and leukocyte adhesion. It creates barriers between endothelial cells and blood and neighbouring cells. The glycocalyx, composed of glycoconjugates and proteoglycans, is an integral component of the ESL and a key element in inter- and intracellular communication and tissue homeostasis. In pathophysiological conditions (atherosclerosis, infection, ischemia/reperfusion injury, diabetes, trauma and acute lung injury) glycocalyx-degrading factors, i.e. reactive oxygen and nitrogen species, matrix metalloproteinases, heparanase and sialidases, damage the ESL, thereby impairing endothelial functions. This leads to increased capillary permeability, leucocyte-endothelium interactions, thrombosis and vascular inflammation, the latter further driving glycocalyx destruction. The present review highlights current knowledge on the vasculoprotective role of the ESL, with specific emphasis on its remodelling in inflammatory vascular diseases and discusses its potential as a novel therapeutic target to treat vascular pathologies. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Ion doping of surface layers in conducting electrical materials

    International Nuclear Information System (INIS)

    Zukowski, P.; Karwat, Cz.; Kozak, Cz. M.; Kolasik, M.; Kiszczak, K.

    2009-01-01

    The presented article gives basic component elements of an implanter MKPCz-99, its parameters and methods for doping surface layers of conducting electrical materials. The discussed device makes possible to dope the materials with ions of gaseous elements. At the application of cones made of solid-element sheets it is possible to perform doping with atoms that do not chemically react with the modified material. By performing voltage drop measurements with a specialized circuit between a movable testing electrode and the modified sample the dependence of transition resistance on pressure force of the testing electrode on the sample can be determined. The testing can be performed at the current passage of a determined value for surfaces modified with ions of gaseous elements or atoms of solid elements. A computer stand for switch testing makes possible to measure temperature of switch contacts and voltage drop at the contact and thereby to determine contact resistance of a switch depending on the number of switch cycles (ON-OFF). Pattern recording of current and voltage at the switch contacts and the application of an adequate computer software makes possible to determined the value of energy between fixed and moving contacts at their getting apart. In order to eliminate action of the environment onto the switch operation measurements can be performed at placing the tested switch together with the driving system in an atmosphere of noble gas like argon. (authors)

  15. Impacts of Ocean Waves on the Atmospheric Surface Layer: Simulations and Observations

    National Research Council Canada - National Science Library

    Sullivan, Peter P; McWilliams, James C; Melville, W. K

    2008-01-01

    ... planetary boundary layers (PBL). Efforts were focused on the effects of surface gravity waves on the near-surface dynamics, surface fluxes, and coupling between the atmospheric and oceanic PBLs...

  16. A Study of the Surface Photovoltage of ZnO-Resin Layers.

    Science.gov (United States)

    Tashiro, I; Kimura, T; Endo, K

    1969-01-01

    The surface photovoltage of ZnO resin layer has been used as the basis for an imaging process generally known as chargeless electrophotography. This paper explores effects of the ambient air pressure and the layer temperature on the surface photovoltage of ZnO resin layers. Experiments were made by using ZnO-silicone resin layer, ZnO-alkyd resin layer, and ZnO-acryl resin layer. The surface potential of the dark adapted layers were measured while the ambient air pressure decreased, and the surface photovoltage and its decay curve were measured under various ambient air pressures. ZnO-silicone resin layer showed a remarkably high sensitivity in terms of surface photovoltage to the ambient air pressure changes. Marked variations were observed in the surface potential of the dark adapted layers both in air and in a vacuum of 5 x 10(-5) Torr when the layer temperature had been slowly raised. The surface potential exhibited a maximum peak when silicone resin was used as a binder and a minimum peak when alkyd resin or acryl resin was used, both peaks being registered at a temperature slightly higher than room temperature in air. After the layers had been annealed for a few hours at a high temperature, relationships between the surface photovoltage and the layer temperature were measured while the layer temperature decreased. The surface photovoltage and its decay of the ZnO-silicone resin layer revealed higher sensitivity to the changes of ambient air pressure and layer temperature than to those of other ZnO-resin layers. This difference is accounted for by a specific property of the silicone resin that enforces adsorption of the water molecule onto the surface of ZnO. Some applications of the above experiments are also discussed.

  17. Banal Nationalism in ESL Textbooks

    Science.gov (United States)

    Gulliver, Trevor

    2011-01-01

    Despite repeating claims that Canadians are less nationalistic than members of other nations, English as a second language (ESL) textbooks often participate in banal repetitions of nation-ness and nationalism. This banal nationalism takes the form of the marking of nation through flags, maps, routine deixis, and nationalized symbols. This study…

  18. ESL Students' Attitudes toward Punctuation

    Science.gov (United States)

    Hirvela, Alan; Nussbaum, Alexander; Pierson, Herbert

    2012-01-01

    Punctuation is a surprisingly underexplored area of second language writing and learning. The small body of published literature about punctuation tends to look at ways in which punctuation can be taught. Little is known, except anecdotally, about how English as a second language (ESL) students actually feel about using English punctuation,…

  19. New Material Development for Surface Layer and Surface Technology in Tribology Science to Improve Energy Efficiency

    Science.gov (United States)

    Ismail, R.; Tauviqirrahman, M.; Jamari, Jamari; Schipper, D. J.

    2009-09-01

    This paper reviews the development of new material and surface technology in tribology and its contribution to energy efficiency. Two examples of the economic benefits, resulted from the optimum tribology in the transportation sector and the manufacturing industry are discussed. The new materials are proposed to modify the surface property by laminating the bulk material with thin layer/coating. Under a suitable condition, the thin layer on a surface can provide a combination of good wear, a low friction and corrosion resistance for the mechanical components. The innovation in layer technology results molybdenum disulfide (MoS2), diamond like carbon (DLC), cubic boron nitride (CBN) and diamond which perform satisfactory outcome. The application of the metallic coatings to carbon fibre reinforced polymer matrix composites (CFRP) has the capacity to provide considerable weight and power savings for many engineering components. The green material for lubricant and additives such as the use of sunflower oil which possesses good oxidation resistance and the use of mallee leaves as bio-degradable solvent are used to answer the demand of the environmentally friendly material with good performance. The tribology research implementation for energy efficiency also touches the simple things around us such as: erasing the laser-print in a paper with different abrasion techniques. For the technology in the engineering surface, the consideration for generating the suitable surface of the components in running-in period has been discussed in order to prolong the components life and reduce the machine downtime. The conclusion, tribology can result in reducing manufacturing time, reducing the maintenance requirements, prolonging the service interval, improving durability, reliability and mechanical components life, and reducing harmful exhaust emission and waste. All of these advantages will increase the energy efficiency and the economic benefits.

  20. Patterning of gold nanoparticles on fluoropolymer films by using patterned surface grafting and layer-by-layer deposition techniques.

    Science.gov (United States)

    Jung, Chang-Hee; Hwang, In-Tae; Jung, Chan-Hee; Choi, Jae-Hak; Kwon, Oh-Sun; Shin, Kwanwoo

    2013-09-11

    The patterning of gold nanoparticles (GNPs) on the surface of a fluoropolymer substrate by using patterned surface grafting and layer-by-layer deposition techniques is described. The surface of a poly(tetrafluoroethylene-co-perfluorovinyl ether) (PFA) substrate was selectively implanted with 150 keV proton ions. Peroxide groups were successfully formed on the implanted PFA surface, and their concentration depended on the fluence. Acrylic acid was graft polymerized onto the implanted regions of the PFA substrate, resulting in well-defined patterns of poly(acrylic acid) (PAA) on the PFA substrate. The surface properties of the PAA-patterned PFA surface, such as chemical compositions, wettability, and morphology, were investigated. The surface analysis results revealed that PAA was definitely present on the implanted regions of the PFA surface, and the degree of grafting was dependent on three factors: fluence, grafting time, and monomer concentration. Furthermore, GNP patterns were generated on the prepared PAA-patterned PFA surface by layer-by-layer deposition of GNPs and poly(diallyldimethyl ammonium chloride). The multilayers of GNPs were deposited only onto the PAA-grafted regions separated by bare PFA regions, and the resulting GNP patterns exhibited good electrical conductivity.

  1. Lateral surface superlattices in strained InGaAs layers

    International Nuclear Information System (INIS)

    Milton, B.

    2000-08-01

    Lateral Surface Superlattices were fabricated by etching in strained InGaAs layers above a GaAs/AlGaAs 2DEG channel. These were etched both by dry plasma wet chemical etching to produce periods of 100nm, 200nm and 300nm. These superlattices were fabricated on Hall bars to allow four terminal measurement and a blanket gate was placed on top, to allow variations in the carrier concentration. The magnetoresistance effects of these superlattices were studied at varying values of gate voltage, which varies the carrier concentration and the electrostatic periodic potential and at temperatures down to 45mK in a dilution refrigerator. From the oscillations observed in the magnetoresistance trace's it is possible to calculate the magnitude of the periodic potential. This showed that the etched, strained InGaAs was producing an anisotropic piezoelectric potential, along with an isotropic electrostatic potential. The variation in period allowed a study of the change of this piezoelectric potential with the period as well as a study of the interactions between the electrostatic and piezoelectric potentials. Further, at the lowest temperatures a strong interaction was observed between the Commensurability Oscillations, caused by the periodic potential, and the Shubnikov-de Haas Oscillations due to the Landau. Levels. This interaction was studied as it varied with temperature and carrier concentration. (author)

  2. Layer-by-layer construction of the heparin/fibronectin coatings on titanium surface:stability and functionality

    Science.gov (United States)

    Li, Guicai; Yang, Ping; Huang, Nan

    Layer-by-layer assembly as a versatile bottom-up nanofabrication technique has been widely used in the development of biomimetic materials with superior mechanical and biological properties. In this study, layer-by-layer assembled heparin/fibronectin biofunctional films were fabricated on titanium (Ti) surface to enhance the blood anticoagulation and accelerate the endothelialization simultaneously. The wettability and chemical changes of the assembled films were investigated by static water contact angle measurement and fourier transform infrared spectroscopy (FTIR). The morphology of modified Ti surfaces were observed using scanning electron microscopy (SEM). The real time assembly process was in-situ monitored by quartz crystal microbalance with dissipation (QCM-D). The stability of the films was evaluated by measuring the changes in wettability and the quantity of heparin and fibronectin on the surfaces. The anticoagulation properties of the films were quantitatively rated using Activated partial thromboplastin time (APTT) analysis. New peaks of hydroxyl and amino group were observed on the assembled Ti srufaces by FTIR. The contact angles varied among the films with different bilayer numbers, indicating the successful graft of the heparin and fibronectin layer-by-layer. QCM-D results showed that the frequency shift increased with the bilayer numbers, and the heparin and fibronectin could form multilayers. The assembly films were stable after incubation in PBS for 24 h based on the results of the contact angle measurement and the quantity of heparin and fibronectin analysis. APTT results suggested that the assembled films kept excellent antithrombotic properties. All these results revealed that the assembled heparin/fibronectin films with stabiltiy and anticoagulation property could be firmly formed on titanium surfaces. Our study further demonstrates that layer-by-layer assembly of heparin and fibronectin will provide a potential and effective tool for

  3. Influence of the surface layer characteristics on the regularities of the cutting process

    Directory of Open Access Journals (Sweden)

    Krainev Dmitriy V.

    2017-01-01

    Full Text Available The article considers the influence of the surface layer characteristics on the regularities of the cutting process and the formation of the quality of the surface machined. This effect has been confirmed by the study results of the combined cutting method with advanced plastic deformation (APD. The work estimates the impact of the change in the surface layer properties on the forces and temperature of cutting, stability of the chip formation and quality parameters of the surface machined.

  4. Surface analysis of topmost layer of epitaxial layered oxide thin film: Application to delafossite oxide for oxygen evolution reaction

    Science.gov (United States)

    Toyoda, Kenji; Adachi, Hideaki; Miyata, Nobuhiro; Hinogami, Reiko; Orikasa, Yuki; Uchimoto, Yoshiharu

    2018-02-01

    Delafossite oxides (ABO2) have a layered structure with alternating layers of A and B elements, the topmost layer of which appears to determine their performance, such as the oxygen evolution reaction (OER) activity. In this study, we investigated the topmost layer of single-domain (0 0 1)-oriented AgCoO2 epitaxial thin film for potential use as an OER catalyst. The thin film was confirmed to possess OER activity at a level comparable to the catalyst in powder form. Atomic scattering spectroscopy revealed the topmost layer to be composed of CoO6 octahedra. In situ X-ray absorption spectroscopy showed that the oxidation of Co at the surface did not change under different potentials, which suggests that there is no valence fluctuation of Co in the stable CoO6 octahedral structure. However, the oxidation number of Co at the surface was lower than that in the bulk. Our density functional theoretical calculations also showed the Co atoms at the surface to have a slightly higher electron occupancy than those in the bulk, and suggests that the unoccupied t2g states of Co at the surface have an influence on OER activity.

  5. Surface modification of layered zirconium phosphates: a novel pathway to multifunctional materials.

    Science.gov (United States)

    Mosby, Brian M; Díaz, Agustín; Clearfield, Abraham

    2014-07-21

    The intercalation of inorganic layered materials has resulted in a wide range of applicability. In such cases the applicability of the material is largely dependent upon the species intercalated within the layer, and the layered material acts largely as a host. Recently, the surface modification of inorganic layered materials has been investigated and it has been shown that the exterior layers can be exclusively functionalized. The advent of surface chemistry allows for the synthesis of particles with both a controlled interlayer and surface. This approach can be used to tailor nanoparticles for specific applications. Herein we review the surface chemistry of α-zirconium bis(monohydrogen orthophosphate) monohydrate (Zr(HPO4)2·H2O, α-ZrP) along with some applications of recent interest. Not only can these reactions be applied to α-ZrP, but similar chemistry can also be expanded to other layered materials and systems.

  6. Identification of a surface layer structure and analysis of humidity ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    institutional effort to probe the atmospheric boundary layer over the monsoon trough over northern India. For this experiment, four micrometeorological towers were set up at four different locations along the normal position of the trough. One such ...

  7. Impacts of Ocean Waves on the Atmospheric Surface Layer: Simulations and Observations

    Science.gov (United States)

    2008-06-06

    than about 5 m s −1 (Makin, Kudryavtsev & Mastenbroek 1995; Banner & Peirson 1998). Ocean boundary layers with vortex force and stochastic breaking...amplitude. Proc. Roy. Soc. Lond. A 342, 157–174. Makin, V. K., Kudryavtsev , V. N. & Mastenbroek, C. 1995 Drag of the sea surface. Boundary- Layer Met. 73...to study some of the impacts of fast-moving waves on marine surface layers (e.g., Gent and Taylor 1976; Gent 1977; Li 1995; Kudryavtsev and Makin 2004

  8. Surface Modification of Titanium with Heparin-Chitosan Multilayers via Layer-by-Layer Self-Assembly Technique

    Directory of Open Access Journals (Sweden)

    Yao Shu

    2011-01-01

    Full Text Available Extracellular matrix (ECM, like biomimetic surface modification of titanium implants, is a promising method for improving its biocompatibility. In this paper chitosan (Chi and heparin (Hep multilayer was coated on pure titanium using a layer-by-layer (LbL self-assembly technique. The Hep-Chi multilayer growth was carried out by first depositing a single layer of positively charged poly-L-lysine (PLL on the NaOH-treated titanium substrate (negatively charged surface, followed by alternate deposition of negatively charged Hep and positively charged Chi, and terminated by an outermost layer of Chi. The multilayer was characterized by DR-FTIR, SEM, and AFM, and osteoblasts were cocultured with the modified titanium and untreated titanium surfaces, respectively, to evaluate their cytocompatibility in vitro. The results confirmed that Hep-Chi multilayer was fabricated gradually on the titanium surface. The Hep-Chi multilayer-coated titanium improved the adhesion, proliferation and differentiation of osteoblasts. Thus, the approach described here may provide a basis for the preparation of modified titanium surfaces for use in dental or orthopedic implants.

  9. Layer-by-Layer Method for the Synthesis and Growth of Surface Mounted Metal-Organic Frameworks (SURMOFs

    Directory of Open Access Journals (Sweden)

    Osama Shekhah

    2010-02-01

    Full Text Available A layer-by-layer method has been developed for the synthesis of metal-organic frameworks (MOFs and their deposition on functionalized organic surfaces. The approach is based on the sequential immersion of functionalized organic surfaces into solutions of the building blocks of the MOF, i.e., the organic ligand and the inorganic unit. The synthesis and growth of different types of MOFs on substrates with different functionalization, like COOH, OH and pyridine terminated surfaces, were studied and characterized with different surface characterization techniques. A controlled and highly oriented growth of very homogenous films was obtained using this method. The layer-by-layer method offered also the possibility to study the kinetics of film formation in more detail using surface plasmon resonance and quartz crystal microbalance. In addition, this method demonstrates the potential to synthesize new classes of MOFs not accessible by conventional methods. Finally, the controlled growth of MOF thin films is important for many applications like chemical sensors, membranes and related electrodes.

  10. Surface layer scintillometry for estimating the sensible heat flux component of the surface energy balance

    Directory of Open Access Journals (Sweden)

    M. J. Savage

    2010-01-01

    Full Text Available The relatively recently developed scintillometry method, with a focus on the dual-beam surface layer scintillometer (SLS, allows boundary layer atmospheric turbulence, surface sensible heat and momentum flux to be estimated in real-time. Much of the previous research using the scintillometer method has involved the large aperture scintillometer method, with only a few studies using the SLS method. The SLS method has been mainly used by agrometeorologists, hydrologists and micrometeorologists for atmospheric stability and surface energy balance studies to obtain estimates of sensible heat from which evaporation estimates representing areas of one hectare or larger are possible. Other applications include the use of the SLS method in obtaining crucial input parameters for atmospheric dispersion and turbulence models. The SLS method relies upon optical scintillation of a horizontal laser beam between transmitter and receiver for a separation distance typically between 50 and 250 m caused by refractive index inhomogeneities in the atmosphere that arise from turbulence fluctuations in air temperature and to a much lesser extent the fluctuations in water vapour pressure. Measurements of SLS beam transmission allow turbulence of the atmosphere to be determined, from which sub-hourly, real-time and in situ path-weighted fluxes of sensible heat and momentum may be calculated by application of the Monin-Obukhov similarity theory. Unlike the eddy covariance (EC method for which corrections for flow distortion and coordinate rotation are applied, no corrections to the SLS measurements, apart from a correction for water vapour pressure, are applied. Also, path-weighted SLS estimates over the propagation path are obtained. The SLS method also offers high temporal measurement resolution and usually greater spatial coverage compared to EC, Bowen ratio energy balance, surface renewal and other sensible heat measurement methods. Applying the shortened surface

  11. Thiol-ene thermosets exploiting surface reactivity for layer-by-layer structures and control of penetration depth for selective surface reactivity

    DEFF Research Database (Denmark)

    Daugaard, Anders Egede; Westh, Andreas; Pereira Rosinha Grundtvig, Ines

    Thiol-ene thermosets have been shown to be an efficient platform for preparation of functional polymer surfaces. Especially the effectiveness and versatility of the system has enabled a large variety of network properties to be obtained in a simple and straight-forward way. Due to its selectivity...... groups in thµe surface of thiol-ene thermosets, it is possible to prepare surface functional thermosets or to exploit the reactive groups for modular construction and subsequent chemical bonding. Here a different approach preparing monolithic layer-by-layer structures with controlled mechanical...... in controlling the penetration depth and surface grafting. The methodology was used for surface immobilization of enzymes providing a direct link between the distribution of enzymes on the surface and the activity of the reactor....

  12. Developing College English as a Second Language (ESL) Programs

    Science.gov (United States)

    Orlova, Irina A.; Kennedy, Jelane A.

    2009-01-01

    This article examines available literature on college English as a Second Language (ESL) programs. The literature available on college ESL programs falls into three categories: (1) research reports and articles, (2) recent theoretical discussions on ESL teaching, and (3) thought pieces discussing college ESL curriculum development and assessment…

  13. Ouch! Or ESL and the Glass Ceiling.

    Science.gov (United States)

    Migliacci, Naomi

    The realities of the glass ceiling, which prevents qualified women, minorities, and many English-as-a-Second-Language (ESL) students from advancement and promotion, are rarely discussed in English for Special Purposes (ESP)/ESL programs and courses. This paper explores the barriers to success, focusing on the sociolinguistic factors of verbal and…

  14. Getting Started in Private ESL Tutoring.

    Science.gov (United States)

    Wurzelbacher, Thelma

    2000-01-01

    Provides tips on how to get started in English-as-a-Second-Language (ESL) private tutoring. Suggests considering three factors before getting started: readiness, market, and service. A readiness profile for private ESL tutoring and a checklist for getting started are included. (Author/VWL)

  15. An Empirical Investigation into Nigerian ESL Learners ...

    African Journals Online (AJOL)

    General observations indicate that ESL learners in Nigeria tend to manifest fear and anxiety in grammar classes, which could influence their performance negatively or positively. This study examines empirically some of the reasons for some ESL learners' apprehension of grammar classes. The data for the study were ...

  16. Standards for Adult Education ESL Programs.

    Science.gov (United States)

    Teachers of English to Speakers of Other Languages, Inc., Alexandria, VA.

    This monograph describes the components of a quality adult education English as a Second Language (ESL) program. The standards reflect the great variety of adult ESL programs in the United States. Part 1, "Introduction," describes issues to be considered in developing standards for program quality and explains how to use the program…

  17. Contextualized Workforce Skills and ESL Learner Identity

    Science.gov (United States)

    Vafai, Maliheh Mansuripur

    2016-01-01

    This article reports on an empirical case study centering on adult ESL learners' motivational patterns for learning English and its relevance to their career goals. It looks at past patterns of immigrant insertion within the socioeconomic context of the US and explores current trends in adult ESL curriculum development focused on the task of…

  18. Collaboration Model for ESL and Content Teachers

    Science.gov (United States)

    Broer, Kathleen

    2013-01-01

    This study will examine strategies that ESL teachers and content teachers can use to help middle school ESL students acquire science vocabulary and meta-cognitive strategies for writing skills in non-fiction text forms. Two appendixes are included. (Contains 3 figures and 2 footnotes.)

  19. Adult ESL Education in the US

    Science.gov (United States)

    Eyring, Janet L.

    2014-01-01

    This article discusses the state of the art in the field of "adult ESL" in the US. It identifies the size, characteristics, and settings of adult education and discusses relevant professional standards, assessment procedures, and teacher preparation. Three approaches to noncredit adult ESL education will be presented (Functional…

  20. Standards for Adult Education ESL Programs

    Science.gov (United States)

    TESOL Press, 2013

    2013-01-01

    What are the components of a quality education ESL program? TESOL's "Standards for Adult Education ESL Programs" answers this question by defining quality components from a national perspective. Using program indicators in eight distinct areas, the standards can be used to review an existing program or as a guide in setting up a new…

  1. A literature review of surface alteration layer effects on waste glass behavior

    International Nuclear Information System (INIS)

    Feng, X.; Cunnane, J.C.; Bates, J.K.

    1993-01-01

    When in contact with an aqueous solution, nuclear waste glass is subject to a chemical attack that results in progressive alteration. During tills alteration, constituent elements of the glass pass into the solution; elements initially in solution diffuse into, or are adsorbed onto, the solid; and new phases appear. This results in the formation of surface layers on the reacted glass. The glass corrosion and radionuclide release can be better understood by investigating these surface layer effects. In the past decade, there have been numerous studies regarding the effects of surface layers on glass reactions. This paper presents a systematic analysis and summary of the past knowledge regarding the effects of surface layers on glass-water interaction. This paper describes the major formation mechanisms of surface layers; reviews the role of surface layers in controlling mass transport and glass reaction affinity (through crystalline phases, an amorphous silica, a gel layer, or all the components in the glass); and discusses how the surface layers contribute to the retention of radionuclides during glass dissolution

  2. Surface passivation investigation on ultra-thin atomic layer deposited aluminum oxide layers for their potential application to form tunnel layer passivated contacts

    Science.gov (United States)

    Xin, Zheng; Ling, Zhi Peng; Nandakumar, Naomi; Kaur, Gurleen; Ke, Cangming; Liao, Baochen; Aberle, Armin G.; Stangl, Rolf

    2017-08-01

    The surface passivation performance of atomic layer deposited ultra-thin aluminium oxide layers with different thickness in the tunnel layer regime, i.e., ranging from one atomic cycle (∼0.13 nm) to 11 atomic cycles (∼1.5 nm) on n-type silicon wafers is studied. The effect of thickness and thermal activation on passivation performance is investigated with corona-voltage metrology to measure the interface defect density D it(E) and the total interface charge Q tot. Furthermore, the bonding configuration variation of the AlO x films under various post-deposition thermal activation conditions is analyzed by Fourier transform infrared spectroscopy. Additionally, poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate) is used as capping layer on ultra-thin AlO x tunneling layers to further reduce the surface recombination current density to values as low as 42 fA/cm2. This work is a useful reference for using ultra-thin ALD AlO x layers as tunnel layers in order to form hole selective passivated contacts for silicon solar cells.

  3. Anticorrosive behaviour of lumefantrine hydrophobic layer on mild steel surface

    Directory of Open Access Journals (Sweden)

    Pavithra M. Krishnegowda

    2016-06-01

    Full Text Available The surface modification of mild steel was achieved by chemical treatment in lumefantrine (LF solution. The surface morphology and wettability of modified surface was analysed by 3D profilometer and contact angle goniometer. The corrosion inhibition performance of modified mild steel surface in 1.0 M HCl solution was investigated by potentiodynamic polarization and electrochemical impedance techniques.Electroche­mical measurements illustrate that the corrosion of mild steel in acidic chloride medium get substantially reduced by introducing LF film on its surface (94 % efficiency. Quantum chemical parameters were evaluated by ab initio method and they confer appropriate theoretical support to the experimental findings.

  4. Surface layer temperature inversion in the Arabian Sea during winter

    Digital Repository Service at National Institute of Oceanography (India)

    Pankajakshan, T.; Ghosh, A.K.

    picture of the actual inversion phenomena occurring in this area. Figure 1 illustrates the procedure adopted in finding the inversion stations. If the temperature difference (Del T) obtained from (T U –T L ) is greater than 0.2°C, then the station... is more or less consistent. Figure 3-A shows the frequency distribution of temperature difference of the inversion layer (Del T). Figure 3-B shows the frequency distribution of the thickness of the inversion layers in meters (Di). Del T is distributed over...

  5. Expansible apparatus for removing the surface layer from a concrete object

    International Nuclear Information System (INIS)

    Allen, C.H.

    1979-01-01

    A method and apparatus for removing the surface layer from a concrete object are described. The method consists of providing a hole having a circular wall in the surface layer of the object, the hole being at least as deep as the thickness of the surface layer to be removed, and applying an outward wedging pressure on the wall of the hole sufficient to spall the surface layer around the hole. By the proper spacing of an appropriate number of holes, it is possible to remove the entire surface layer. The apparatus consists of an elongated tubular-shaped body having a relatively short handle with a solid wall at one end. The wall of the remainder of the body contains a plurality of evenly spaced longitudinal cuts to form a relatively long expandable section. The outer end of the expandable section has an expandable, wedge-shaped spalling edge extending from the outer surface of the wall, perpendicular to the longitudinal axis of the body, and expanding means in the body for outwardly expanding the expandable section and forcing the spalling edge into the wall of a hole with sufficient outward pressure to spall away the surface layer of concrete. The method and apparatus are particularly suitable for removing surface layers of concrete which are radioactively contaminated

  6. Surface modification of passive iron by alkyl-phosphonic acid layers

    Energy Technology Data Exchange (ETDEWEB)

    Paszternak, A. [Chemical Research Center of the Hungarian Academy of Sciences, 1025 Budapest, Pusztaszeri ut 59-67 (Hungary); Stichleutner, S. [Research Group for Nuclear Methods in Structural Chemistry, Hungarian Academy of Sciences, Institute of Chemistry, Eoetvoes Lorand University, 1117 Budapest, Pazmany P. setany 1/a (Hungary); Felhosi, I.; Keresztes, Z. [Chemical Research Center of the Hungarian Academy of Sciences, 1025 Budapest, Pusztaszeri ut 59-67 (Hungary); Nagy, F.; Kuzmann, E.; Vertes, A.; Homonnay, Z. [Research Group for Nuclear Methods in Structural Chemistry, Hungarian Academy of Sciences, Institute of Chemistry, Eoetvoes Lorand University, 1117 Budapest, Pazmany P. setany 1/a (Hungary); Peto, G. [Research Institute for Technical Physics and Materials Science of the Hungarian Academy of Sciences, 1121 Budapest, Konkoly Thege ut 29-33 (Hungary); Kalman, E. [Chemical Research Center of the Hungarian Academy of Sciences, 1025 Budapest, Pusztaszeri ut 59-67 (Hungary)], E-mail: erika.kalman@chemres.hu

    2007-12-01

    Phosphonate layer formation on passive iron surface has been investigated by electrochemical, conversion electron Moessbauer spectroscopy (CEMS) and atomic force microscopy (AFM) techniques. Electrochemical methods revealed that the prepassivation of iron surface results in stabilization of the phosphonate layer exhibiting favorable corrosion resistance. The rate of anodic dissolution is continuously decreasing due to the time-dependent formation of a protective phosphonate layer. The large R{sub ct} values of 1-20 M{omega} cm{sup 2} indicate rather high blocking effect of metal dissolution by the phosphonate layer. The phosphonate layer formation has been also followed by the decrease of capacitance. CEMS investigations were carried out to evaluate the differences in the composition of the passive layer as a result of the phosphonate treatment. Moessbauer spectroscopy indicated the presence of iron phosphonate. Changes in morphology due to the phosphonate layer formation have been observed.

  7. Effects of fluid layer at micropolar orthotropic boundary surface

    Indian Academy of Sciences (India)

    The displacement, microrotation and stress components for a micropolar orthotropic elastic solid so obtained in the physical domain are computed numerically by applying the numerical inversion technique. Micropolarity and anisotropy effects along with that of the depth of the fluid layer on various expressions have been ...

  8. Effects of fluid layer at micropolar orthotropic boundary surface

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Abstract. Effects of a fluid layer at a micropolar orthotropic elastic solid inter- face to a moving point load have been studied. After using the Fourier transform an eigen value approach has been employed to solve the problem. The displacement, microrotation and stress components for a micropolar orthotropic elastic solid so.

  9. The nanostructure and microstructure of SiC surface layers deposited by MWCVD and ECRCVD

    Science.gov (United States)

    Dul, K.; Jonas, S.; Handke, B.

    2017-12-01

    Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) have been used to investigate ex-situ the surface topography of SiC layers deposited on Si(100) by Microwave Chemical Vapour Deposition (MWCVD) -S1,S2 layers and Electron Cyclotron Resonance Chemical Vapor Deposition (ECRCVD) - layers S3,S4, using silane, methane, and hydrogen. The effects of sample temperature and gas flow on the nanostructure and microstructure have been investigated. The nanostructure was described by three-dimensional surface roughness analysis based on digital image processing, which gives a tool to quantify different aspects of surface features. A total of 13 different numerical parameters used to describe the surface topography were used. The scanning electron image (SEM) of the microstructure of layers S1, S2, and S4 was similar, however, layer S3 was completely different; appearing like grains. Nonetheless, it can be seen that no grain boundary structure is present in the AFM images.

  10. Electric double layer interactions in bacterial adhesion to surfaces

    NARCIS (Netherlands)

    Poortinga, AT; Norde, W; Busscher, HJ; Bos, R.R.M.

    2002-01-01

    The DLVO (Derjaguin, Landau, Verwey, Overbeek) theory was originally developed to describe interactions between non-biological lyophobic colloids such as polystyrene particles, but is also used to describe bacterial adhesion to surfaces. Despite the differences between the surface of bacteria and

  11. X-ray evaluation of residual stress distributions within surface machined layer generated by surface machining and sequential welding

    International Nuclear Information System (INIS)

    Taniguchi, Yuu; Okano, Shigetaka; Mochizuki, Masahito

    2017-01-01

    The excessive tensile residual stress generated by welding after surface machining may be an important factor to cause stress corrosion cracking (SCC) in nuclear power plants. Therefore we need to understand and control the residual stress distribution appropriately. In this study, residual stress distributions within surface machined layer generated by surface machining and sequential welding were evaluated by X-ray diffraction method. Depth directional distributions were also investigated by electrolytic polishing. In addition, to consider the effect of work hardened layer on the residual stress distributions, we also measured full width at half maximum (FWHM) obtained from X-ray diffraction. Testing material was a low-carbon austenitic stainless steel type SUS316L. Test specimens were prepared by surface machining with different cutting conditions. Then, bead-on-plate welding under the same welding condition was carried out on the test specimens with different surface machined layer. As a result, the tensile residual stress generated by surface machining increased with increasing cutting speed and showed nearly uniform distributions on the surface. Furthermore, the tensile residual stress drastically decreased with increasing measurement depth within surface machined layer. Then, the residual stress approached 0 MPa after the compressive value showed. FWHM also decreased drastically with increasing measurement depth and almost constant value from a certain depth, which was almost equal regardless of the machining condition, within surface machined layer in all specimens. After welding, the transverse distribution of the longitudinal residual stress varied in the area apart from the weld center according to machining conditions and had a maximum value in heat affected zone. The magnitude of the maximum residual stress was almost equal regardless of the machining condition and decreased with increasing measurement depth within surface machined layer. Finally, the

  12. Dynamical structure of the turbulent boundary layer on rough surface

    Czech Academy of Sciences Publication Activity Database

    Uruba, Václav; Jonáš, Pavel; Hladík, Ondřej

    2011-01-01

    Roč. 11, č. 1 (2011), s. 603-604 ISSN 1617-7061 R&D Projects: GA ČR GA101/08/1112; GA ČR GAP101/10/1230 Institutional research plan: CEZ:AV0Z20760514 Keywords : turbulent boundary layer * rough wall * hairpin vortex Subject RIV: BK - Fluid Dynamics http://onlinelibrary.wiley.com/doi/10.1002/pamm.201110291/abstract

  13. Al2O3 dielectric layers on H-terminated diamond: Controlling surface conductivity

    Science.gov (United States)

    Yang, Yu; Koeck, Franz A.; Dutta, Maitreya; Wang, Xingye; Chowdhury, Srabanti; Nemanich, Robert J.

    2017-10-01

    This study investigates how the surface conductivity of H-terminated diamond can be preserved and stabilized by using a dielectric layer with an in situ post-deposition treatment. Thin layers of Al2O3 were grown by plasma enhanced atomic layer deposition (PEALD) on H-terminated undoped diamond (100) surfaces. The changes of the hole accumulation layer were monitored by correlating the binding energy of the diamond C 1s core level with electrical measurements. The initial PEALD of 1 nm Al2O3 resulted in an increase of the C 1s core level binding energy consistent with a reduction of the surface hole accumulation and a reduction of the surface conductivity. A hydrogen plasma step restored the C 1s binding energy to the value of the conductive surface, and the resistance of the diamond surface was found to be within the range for surface transfer doping. Further, the PEALD growth did not appear to degrade the surface conductive layer according to the position of the C 1s core level and electrical measurements. This work provides insight into the approaches to establish and control the two-dimensional hole-accumulation layer of the H-terminated diamond and improve the stability and performance of H-terminated diamond electronic devices.

  14. Abrasive wear mechanisms and surface layer structure of refractory materials after mechanical working

    International Nuclear Information System (INIS)

    Milman, Y.V.; Lotsko, D.V.

    1989-01-01

    The mechanisms of abrasive wear and surface layer structure formation after different kinds of mechanical working are considered in terms of fracture and plastic deformation mechanisms for various refractory materials. The principles for classification of abrasive wear mechanisms are proposed, the four types of wear mechanisms are distinguished for various combinations of fractures and plastic deformation types. The concept of characteristic deformation temperature t * (knee temperature) is used. Detailed examples are given of investigating the surface layer structures in grinded crystals of sapphire and molybdenum. The amorphisation tendency of the thinnest surface layer while mechanical polishing is discussed separately. 19 refs., 11 figs., 2 tabs. (Author)

  15. Influence of the Surface Layer on the Electrochemical Deposition of Metals and Semiconductors into Mesoporous Silicon

    Energy Technology Data Exchange (ETDEWEB)

    Chubenko, E. B., E-mail: eugene.chubenko@gmail.com; Redko, S. V.; Sherstnyov, A. I.; Petrovich, V. A.; Kotov, D. A.; Bondarenko, V. P. [Belarusian State University of Information and RadioElectronics (Belarus)

    2016-03-15

    The influence of the surface layer on the process of the electrochemical deposition of metals and semiconductors into porous silicon is studied. It is shown that the surface layer differs in structure and electrical characteristics from the host porous silicon bulk. It is established that a decrease in the conductivity of silicon crystallites that form the surface layer of porous silicon has a positive effect on the process of the filling of porous silicon with metals and semiconductors. This is demonstrated by the example of nickel and zinc oxide. The effect can be used for the formation of nanocomposite materials on the basis of porous silicon and nanostructures with a high aspect ratio.

  16. Hard Surface Layers by Pack Boriding and Gaseous Thermo-Reactive Deposition and Diffusion Treatments

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lundin; Bottoli, Federico; Dahl, Kristian Vinter

    2017-01-01

    subjected to TRD (chromizing and titanizing) and boriding treatments. For the steels with low carbon content, chromizing results in surface alloying with chromium, i.e., formation of a (soft) “stainless” surface zone. Steels containing higher levels of carbon form chromium carbide (viz. Cr23C6, Cr7C3......) layers with hardnesses up to 1800 HV. Titanizing of ARNE tool steel results in a surface layer consisting of TiC with a hardness of approximately 4000 HV. Duplex treatments, where boriding is combined with subsequent (TRD) titanizing, result in formation of hard TiB2 on top of a thick layer of Fe...

  17. Study on the influence of carbon monoxide to the surface oxide layer of uranium metal

    International Nuclear Information System (INIS)

    Wang Xiaolin; Duan Rongliang; Fu Yibei; Xie Renshou; Zuo Changming; Zhao Chunpei; Chen Hong

    1997-01-01

    The influence of carbon monoxide to the surface oxide layer of uranium metal has been studied by X-ray photoelectron spectroscopy (XPS) and gas chromatography (GC). Carbon monoxide adsorption on the oxide layer resulted in U4f peak shifting to the lower binding energy. The content of oxygen in the oxide is decreased and the atomic ratio (O/U) is decreased by 7.2%. The amount of carbon dioxide in the atmosphere after the surface reaction is increased by 11.0%. The investigation indicates that the surface layer can prevent the further oxidation uranium metal in the atmosphere of carbon monoxide

  18. The microstructure of the surface layer of magnesium laser alloyed with aluminum and silicon

    International Nuclear Information System (INIS)

    Dziadoń, Andrzej; Mola, Renata; Błaż, Ludwik

    2016-01-01

    The surface layer under analysis was formed as a result of diffusion bonding of a thin AlSi20 plate to a magnesium substrate followed by laser melting. Depending on the process parameters, the laser beam melted the AlSi20 plate only or the AlSi20 plate and a layer of the magnesium surface adjacent to it. Two types of microstructure of the remelted layer were thus analyzed. If the melting zone was limited to the AlSi20 plate, the microstructure of the surface layer was typical of a rapidly solidified hypereutectic Al–Si alloy. Since, however, the liquid AlSi20 reacted with the magnesium substrate, the following intermetallic phases formed: Al 3 Mg 2 , Mg 17 Al 12 and Mg 2 Si. The microstructure of the modified surface layer of magnesium was examined using optical, scanning electron and transmission electron microscopy. The analysis of the surface properties of the laser modified magnesium revealed that the thin layer has a microstructure of a rapidly solidified Al–Si alloy offering good protection against corrosion. By contrast, the surface layer containing particles of intermetallic phases was more resistant to abrasion but had lower corrosion resistance than the silumin type layer. - Highlights: •A CO 2 laser was used for surface alloying of Mg with AlSi20. •Before alloying, an AlSi20 plate was diffusion bonded with the Mg substrate. •The process parameters affected the alloyed layer microstructure and properties. •With melting limited to AlSi20, the layer had a structure of rapidly solidified AlSi20. •Mg–Al and Mg–Si phases were present when both the substrate and the plate were melted.

  19. Effect of Cholesterol on the Stability and Lubrication Efficiency of Phosphatidylcholine Surface Layers

    NARCIS (Netherlands)

    Sorkin, Raya; Kampf, Nir; Klein, Jacob

    2017-01-01

    The lubrication properties of saturated PC lipid vesicles containing high cholesterol content under high loads were examined by detailed surface force balance measurements of normal and shear forces between two surface-attached lipid layers. Forces between two opposing mica surfaces bearing

  20. Research Note : Near-surface layer replacement for sparse data: Is interpolation needed?

    NARCIS (Netherlands)

    Sun, Yimin; Verschuur, D.J.; Luo, Yi

    2017-01-01

    Near-surface problem is a common challenge faced by land seismic data processing, where often, due to near-surface anomalies, events of interest are obscured. One method to handle this challenge is near-surface layer replacement, which is a wavefield reconstruction process based on downward

  1. Influence of changes in surface layer properties on tire/pavement noise

    NARCIS (Netherlands)

    Li, M.; Van Keulen, W.; Ceylan, H.; Van de Ven, M.F.C.; Molenaar, A.A.A.

    2013-01-01

    This paper investigates changes in tire/pavement noise caused by variations in the road surface characteristics. This research is based on the analysis of noise and surface characteristics collected from sections with 25 mm thickness thin layer surfacings in the Netherlands. Investigations are first

  2. Laminar boundary layer response to rotation of a finite diameter surface patch

    International Nuclear Information System (INIS)

    Klewicki, J.C.; Hill, R.B.

    2003-01-01

    The responses of the flat plate laminar boundary layer to perturbations generated by rotating a finite patch of the bounding surface are explored experimentally. The size of the surface patch was of the same order as the boundary layer thickness. The displacement thickness Reynolds number range of the boundary layers explored was 72-527. The rotation rates of the surface patch ranged from 2.14 to 62.8 s-1. Qualitative flow visualizations and quantitative molecular tagging velocimetry measurements revealed that rotation of a finite surface patch generates an asymmetric loop-like vortex. Significant features of this vortex include that, (i) the sign of the vorticity in the vortex head is opposite that of the boundary layer vorticity regardless of the sign of the input rotation, (ii) one leg of the vortex exhibits motion akin to solid body rotation while the other leg is best characterized as a spanwise shear layer, (iii) the vortex leg exhibiting near solid body rotation lifts more rapidly from the surface than the leg more like a shear layer, and (iv) the vortex leg exhibiting near solid body rotation always occurs on the side of the surface patch experiencing downstream motion. These asymmetries switch sides depending on the sign of the input rotation. The present results are interpreted and discussed relative to analytical solutions for infinite geometries. By way of analogy, plausible connections are drawn between the present results and the influences of wall normal vortices in turbulent boundary layer flows

  3. Reading and esl writers Reading and esl writers

    Directory of Open Access Journals (Sweden)

    John R. Edlund

    2008-04-01

    Full Text Available Whether the student population consists of basic writers, non-native speakers, or well-prepared freshmen and whether the primary goal of the class is improvement in writing ability, language and vocabulary acquisition, or critical thinking skills, there is considerable evidence that substantial amounts of reading arc an essential component of the course (See Krashen Writing: Research, Theory and Applications for a summary. This is especially true in the ESL composition class, where language acquisition is still a major factor in the student's success as a writer. Whether the student population consists of basic writers, non-native speakers, or well-prepared freshmen and whether the primary goal of the class is improvement in writing ability, language and vocabulary acquisition, or critical thinking skills, there is considerable evidence that substantial amounts of reading arc an essential component of the course (See Krashen Writing: Research, Theory and Applications for a summary. This is especially true in the ESL composition class, where language acquisition is still a major factor in the student's success as a writer.

  4. [Texture variation of CC 5052 aluminum alloy slab from surface to center layer by XRD].

    Science.gov (United States)

    Chen, Ming-Biao; Liu, Wen-Chang; Ma, Xiao-Yi; Li, Jian; Yang, Qing-Xiang; Wang, Shan; Ma, Min; Liu, Chang; Zhao, Y M

    2013-05-01

    For improvement of the processing and gaining uniformity texture structure and performance of direct chill cast CCAA 5052 aluminum alloy band after first hot rolling with different reduction, the material was annealed at 454 degrees C and then cold rolling with different reduction was conducted, the texture at surface, quarter and center layer of the sample was tested and examined by X-ray diffraction method, the data calculated using special software and the difference of texture at surface, quarter and center layer was analyzed. There existed an elevated gradient of intensity from surface layer to center layer after cold rolled with less than or equal to 40% reduction, The main texture of beta is stronger mainly due to transformation from remainder exposure, while the goss and remainder is infirm, the state of texture at each layer is close to each other after cold rolling with reduction high than 56.1%.

  5. Seasonal features of atmospheric surface-layer characteristics over a tropical coastal station in Southern India

    International Nuclear Information System (INIS)

    Hari Prasad, K.B.R.R.; Srinivas, C.V.; Baskaran, R.; Venkatraman, B.

    2016-01-01

    Dispersion of air-borne effluents occurs in the atmospheric boundary layer (ABL) where turbulence is the main physical processes. In the surface layer of ABL, the mechanical (shear) generation of turbulence exceeds the buoyant generation or consumption of turbulence. In this layer, under steady state and horizontally homogeneous conditions various forces in the governing equation can be neglected and one can apply Monin-Obukhov Similarity Theory (MOST) to estimate the turbulent fluxes and other surface layer variables. Understanding the turbulent characteristics of the surface layer is vital for modeling of turbulent diffusion in regional numerical weather and pollution dispersion models. The objective of this study is to verify the validity of the MOST at the coastal site Kalpakkam under various atmospheric stability conditions with respect to different seasons for modeling atmospheric dispersion of radioactive effluents

  6. Surface passivation of GaAs nanowires by the atomic layer deposition of AlN

    Energy Technology Data Exchange (ETDEWEB)

    Shtrom, I. V., E-mail: igorstrohm@mail.ru; Bouravleuv, A. D. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Samsonenko, Yu. B.; Khrebtov, A. I. [Russian Academy of Sciences, St. Petersburg National Research Academic University—Nanotechnology Research and Education Center (Russian Federation); Soshnikov, I. P. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Reznik, R. R.; Cirlin, G. E., E-mail: cirlin@beam.ioffe.ru [Russian Academy of Sciences, St. Petersburg National Research Academic University—Nanotechnology Research and Education Center (Russian Federation); Dhaka, V.; Perros, A.; Lipsanen, H. [Aalto University (Finland)

    2016-12-15

    It is shown that the atomic layer deposition of thin AlN layers can be used to passivate the surface states of GaAs nanowires synthesized by molecular-beam epitaxy. Studies of the optical properties of samples by low-temperature photoluminescence measurements shows that the photoluminescence-signal intensity can be increased by a factor of up to five by passivating the nanowires with a 25-Å-thick AlN layer.

  7. ETHNOGRAPHIC APPROACH TO EFL/ESL RESEARCH

    Directory of Open Access Journals (Sweden)

    Nikolaus Pasassung

    2016-10-01

    Full Text Available This article shows that ethnography, as an approach, is a very useful tool to be applied in research attempting a good understanding of EFL/ESL classrooms. With reference to work done by anthropologists and classroom researchers, the pre- sent article argues that education, including EFL/ESL classrooms, can be well un- derstood by using ethnographic  approaches.  This is done by elaborating  the rele- vance of ethnography and the classroom context in the sense that ethnographic prin- ciples are applicable in describing and understanding the culture of a classroom, and EFL/ESL teaching in particular.

  8. Seasonal cyclogenesis and the role of near-surface stratified layer in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, V.S.N.; Sarma, M.S.S.; Tilvi, V.

    The role of the near-surface stratified layer developed due to the spread of low salinity waters under the influence of freshwater influx on the cyclogenesis over the Bay of Bengal is addressed. The seasonal variation of the Effective Oceanic Layer...

  9. Formation of Titanium Carbide in the Surface Layer of Cavityless-Cast Iron-Carbon Alloys

    Science.gov (United States)

    Ovcharenko, P. G.; Leshchev, A. Yu.; Makhneva, T. M.

    2018-01-01

    Special features of formation of titanium carbide in the surface layer of castings of iron-carbon alloys obtained with the use of investment patterns and "Ti - C" and "FeTi - C" alloying compositions are considered. The phase composition, the structure, and the hardness of the alloyed layers are determined.

  10. A manufacturing method for multi-layer polysilicon surface-micromachining technology

    Energy Technology Data Exchange (ETDEWEB)

    Sniegowski, J.J.; Rodgers, M.S.

    1998-01-01

    An advanced manufacturing technology which provides multi-layered polysilicon surface micromachining technology for advanced weapon systems is presented. Specifically, the addition of another design layer to a 4 levels process to create a 5 levels process allows consideration of fundamentally new architecture in designs for weapon advanced surety components.

  11. Time-resolved PIV measurements of the atmospheric boundary layer over wind-driven surface waves

    Science.gov (United States)

    Markfort, Corey; Stegmeir, Matt

    2017-11-01

    Complex interactions at the air-water interface result in two-way coupling between wind-driven surface waves and the atmospheric boundary layer (ABL). Turbulence generated at the surface plays an important role in aquatic ecology and biogeochemistry, exchange of gases such as oxygen and carbon dioxide, and it is important for the transfer of energy and controlling evaporation. Energy transferred from the ABL promotes the generation and maintenance of waves. A fraction of the energy is transferred to the surface mixed layer through the generation of turbulence. Energy is also transferred back to the ABL by waves. There is a need to quantify the details of the coupled boundary layers of the air-water system to better understand how turbulence plays a role in the interactions. We employ time-resolved PIV to measure the detailed structure of the air and water boundary layers under varying wind and wave conditions in the newly developed IIHR Boundary-Layer Wind-Wave Tunnel. The facility combines a 30-m long recirculating water channel with an open-return boundary layer wind tunnel. A thick turbulent boundary layer is developed in the 1 m high air channel, over the water surface, allowing for the study of boundary layer turbulence interacting with a wind-driven wave field.

  12. Investigation of Corrosion and Cathodic Protection in Reinforced Concrete. II : Properties of Steel Surface Layers

    NARCIS (Netherlands)

    Koleva, D.A.; De Wit, J.H.W.; Van Breugel, K.; Lodhi, Z.F.; Ye, G.

    2007-01-01

    The present study explores the formation of corrosion products on the steel surface (using as-received low carbon construction steel) in reinforced concrete in conditions of corrosion and subsequent transformation of these layers in conditions of cathodic protection (CP).

  13. The influence of wind speed on surface layer stability and turbulent ...

    Indian Academy of Sciences (India)

    wind regime (Mahrt et al. ... Influence of wind speed on surface layer stability and turbulent fluxes. 1401. Table 1. Specifications of the eddy ..... different soil and vegetation properties and other regional climatic factors. Earlier, it was found that.

  14. A parametric description of a skewed puff in the diabatic surface layer

    International Nuclear Information System (INIS)

    Mikkelsen, T.

    1982-10-01

    The spreading of passive material in the stable, neutral and unstable surface layer from an instantaneous ground source is parameterized in a form appropriate for use with an operational puff diffusion model. (author)

  15. FORMING A PARTING LAYER OF COATING ON THE SURFACE OF THE MOULD DURING DIE-CASTING

    Directory of Open Access Journals (Sweden)

    A. Pivovarchik

    2015-01-01

    Full Text Available The paper presents the results of research on the study of the possibility of accumulation of the lubricating layer coating on the surface of the separation process of foundry equipment with high pressure die casting aluminum alloys.

  16. Experimental Investigation of Surface Layer Properties of High Thermal Conductivity Tool Steel after Electrical Discharge Machining

    Directory of Open Access Journals (Sweden)

    Rafał Świercz

    2017-12-01

    Full Text Available New materials require the use of advanced technology in manufacturing complex shape parts. One of the modern materials widely used in the tool industry for injection molds or hot stamping dies is high conductivity tool steel (HTCS 150. Due to its hardness (55 HRC and thermal conductivity at 66 W/mK, this material is difficult to machine by conventional treatment and is being increasingly manufactured by nonconventional technology such as electrical discharge machining (EDM. In the EDM process, material is removed from the workpiece by a series of electrical discharges that cause changes to the surface layers properties. The final state of the surface layer directly influences the durability of the produced elements. This paper presents the influence of EDM process parameters: discharge current Ic and the pulse time ton on surface layer properties. The experimental investigation was carried out with an experimental methodology design. Surface layers properties including roughness 3D parameters, the thickness of the white layer, heat affected zone, tempered layer and occurring micro cracks were investigated and described. The influence of the response surface methodology (RSM of discharge current Ic and the pulse time ton on the thickness of the white layer and roughness parameters Sa, Sds and Ssc were described and established.

  17. Thermographic analysis of plasma facing components covered by carbon surface layer in tokamaks

    International Nuclear Information System (INIS)

    Gardarein, Jean-Laurent

    2007-01-01

    Tokamaks are reactors based on the thermonuclear fusion energy with magnetic confinement of the plasma. In theses machines, several MW are coupled to the plasma for about 10 s. A large part of this power is directed towards plasma facing components (PFC). For better understanding and control the heat flux transfer from the plasma to the surrounding wall, it is very important to measure the surface temperature of the PFC and to estimate the imposed heat flux. In most of tokamaks using carbon PFC, the eroded carbon is circulating in the plasma and redeposited elsewhere. During the plasma operations, this leads at some locations to the formation of thin or thick carbon layers usually poorly attached to the PFC. These surface layers with unknown thermal properties complicate the calculation of the heat flux from IR surface temperature measurements. To solve this problem, we develop first, inverse method to estimate the heat flux using thermocouple (not sensitive to the carbon surface layers) temperature measurements. Then, we propose a front face pulsed photothermal method allowing an estimation of layers thermal diffusivity, conductivity, effusivity and the thermal contact resistance between the layer and the tile. The principle is to study with an infrared sensor, the cooling of the layer surface after heating by a short laser pulse, this cooling depending on the thermal properties of the successive layers. (author) [fr

  18. Three Dimensional Dynamics of Freshwater Lenses in the Oceans Near Surface Layer

    Science.gov (United States)

    2016-09-14

    the potential impact of these fluxes on the barrier layer and Aquarius and Soil Moisture and Ocean Salinity (SMOS) satellite image formations. By...contributing to the salinity field detected in the Aquarius and Soil Moisture and Ocean Salinity (SMOS) sat- ellite footprints. The barrier layer (Lukas...operational algorithms for sea surface salinity satellites. Oceanic advection and mixing funda- mentally affect the sea surface salinity sig - nal

  19. Boron Diffused Thermoluminescent Surface Layer in LiF TLDs for Skin Dose Assessments

    DEFF Research Database (Denmark)

    Christensen, Poul; Majborn, Benny

    1980-01-01

    A new high-temperature glow peak produced in a thin surface layer of LiF TLDs by diffusion of boron into the LiF material has been studied for skin dose assessments in personnel dosimetry.......A new high-temperature glow peak produced in a thin surface layer of LiF TLDs by diffusion of boron into the LiF material has been studied for skin dose assessments in personnel dosimetry....

  20. Streams and magnetic fields in surface layers of Ap-stars

    International Nuclear Information System (INIS)

    Dolginov, A.Z.; Urpin, V.A.

    1978-01-01

    Magnetic field generation of Ap-stars is considered. It is shown that in the surface layers of Ap-stars inhomogeneity of chemical composition produces a strong magnetic field. Velocities of possible circulation of stellar matter are estimated. It is shown that circulation does not prevent the process of the magnetic field generation. It needs the order of million years, for arranging the stationary magnetic field in surface layers

  1. The surface layer of austempered ductile iron investment castings properties

    Directory of Open Access Journals (Sweden)

    D. Myszka

    2009-01-01

    Full Text Available The article presents a unique process of carbonnitriding and nitriding the precision casting surfaces of austempered ductile iron. The results of the research are pointing that adequate process parameters allow to obtain multiple increase of wear resistance and a significant increase of corrosion resistance. Also, changes of cast microstructure and hardness are presented.

  2. Surface reactivity and layer analysis of chemisorbed reaction films in ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Studies on surface reactivity of substrate iron (Fe-particles) were made in the tribo-chemical environment of alkyl octadecenoates. Two alkyl octadecenoates namely ethyl octadecenoate and methyl. 12-hydroxy octadecenoate, slightly different in their chemical nature, were taken for preparing the chemisorbed ...

  3. Surface reactivity and layer analysis of chemisorbed reaction films in ...

    Indian Academy of Sciences (India)

    Administrator

    Studies on surface reactivity of substrate iron (Fe-particles) were made in the tribo-chemical environment of alkyl octadecenoates. Two alkyl octadecenoates namely ethyl octadecenoate and methyl. 12-hydroxy octadecenoate, slightly different in their chemical nature, were taken for preparing the chemisorbed reaction films ...

  4. Influence of carbon monoxide to the surface layer of uranium metal and its oxides

    International Nuclear Information System (INIS)

    Wang Xiaoling; Fu Yibei; Xie Renshou; Huang Ruiliang

    1996-09-01

    The surface structures of uranium metal and triuranium octaoxide (U 3 O 8 ) and the influence of carbon monoxide to the surface layers have been studied by X-ray photoelectron spectroscopy (XPS). After exposure to carbon monoxide, contents of oxygen in the surface oxides of uranium metal and U 3 O 8 are decreased and O/U ratios decrease 7.2%, 8.0% respectively. The investigation indicated the surface layers of uranium metal and its oxides were forbidden to further oxidation in the atmosphere of carbon monoxide. (11 refs., 9 figs., 2 tabs.)

  5. EMF measurements across the front of combustion wave during layer by layer surface laser sintering of exothermal powder compositions

    Science.gov (United States)

    Shishkovskiy, I.; Sherbakov, V.; Morozov, Yu.

    2007-06-01

    Rapid prototyping (RP) and manufacturing (M) is a novel layer-by-layer fabrication technique which has become increasingly popular due to its inherent flexibility for the manufacture of simple and complex 3D parts. Early we had been shown opportunity of selective laser sintering (SLS) of different type powder systems (intermetallics, ceramics, ferrites, high-temperature superconductors), traditional use for self-propagated high-temperature synthesis (SHS). The non-thermal heating affect of an external electromagnetic field during SHS is related to the specific system under study due to differences in movement of defects and ions at the 'plasma-like' molten combustion wave front. We have developed and refined the testing scheme for electro-thermal phenomena studies which can directly influence on the SHS combustion wave front. This work studies electromotive force (EMF) measurements across the front of combustion wave during layer by layer surface laser sintering of exothermal powder compositions (Ni-Ti, Ni-Al). Analysis using an analog-digital-analog computer converter allowed some control of the laser movement and hence some control of the exothermal reaction - in so doing it provided near optimum conditions for forming layered 3D articles. Comparative results of structural-phase transformation during laser control SHS in reaction-capable compositions are presented.

  6. Effect of High-Speed Milling Parameters on Surface Metamorphic Layer of TC17 Titanium Alloy

    Directory of Open Access Journals (Sweden)

    TAN Liang

    2017-12-01

    Full Text Available In order to provide the relatively accurate experimental basis for optimizing parameters and controlling surface metamorphic layer, ball end high-speed milling experiments of TC17 titanium alloy were carried out utilizing one of experimental design techniques based on the response surface methodology. The surface roughness prediction model was built, variance analyses were applied to check the significances of surface roughness model and input parameters, the effect of parameters on surface roughness was analyzed. Meanwhile, the residual stress, microhardness and microstructure under the condition of high, medium and low level of parameters were investigated. Results indicate that the model can predict the surface roughness effectively and feed per tooth and radial depth of cut have an obvious effect on surface roughness. Compressive residual stresses are detected on all milled surfaces and surface residual stresses are increased with the increase of the level of the milling parameters. The compressive residual stress layer is approximately 20 μm regardless of milling parameters level used. The process of thermal softening, then work hardening, and finally tending to stabilize are observed in the microhardness profiles. Grains of the surface layer are broken and bent, the thickness of plastic deformation layer is approximately 10 μm.

  7. The Influence of the Tool Surface Texture on Friction and the Surface Layers Properties of Formed Component

    Directory of Open Access Journals (Sweden)

    Jana Šugárová

    2018-03-01

    Full Text Available The morphological texturing of forming tool surfaces has high potential to reduce friction and tool wear and also has impact on the surface layers properties of formed material. In order to understand the effect of different types of tool textures, produced by nanosecond fibre laser, on the tribological conditions at the interface tool-formed material and on the integrity of formed part surface layers, the series of experimental investigations have been carried out. The coefficient of friction for different texture parameters (individual feature shape, including the depth profile of the cavities and orientation of the features relative to the material flow was evaluated via a Ring Test and the surface layers integrity of formed material (surface roughness and subsurface micro hardness was also experimentally analysed. The results showed a positive effect of surface texturing on the friction coefficients and the strain hardening of test samples material. Application of surface texture consisting of dimple-like depressions arranged in radial layout contributed to the most significant friction reduction of about 40%. On the other hand, this surface texture contributed to the increase of surface roughness parameters, Ra parameter increased from 0.49 μm to 2.19 μm and the Rz parameter increased from 0.99 μm to 16.79 μm.

  8. Retention in the Golgi apparatus and expression on the cell surface of Cfr/Esl-1/Glg-1/MG-160 are regulated by two distinct mechanisms.

    Science.gov (United States)

    Miyaoka, Yuichiro; Kato, Hidenori; Ebato, Kazuki; Saito, Shigeru; Miyata, Naoko; Imamura, Toru; Miyajima, Atsushi

    2011-11-15

    Cfr (cysteine-rich fibroblast growth factor receptor) is an Fgf (fibroblast growth factor)-binding protein without a tyrosine kinase. We have shown previously that Cfr is involved in Fgf18 signalling via Fgf receptor 3c. However, as Cfr is also known as Glg (Golgi apparatus protein)-1 or MG-160 and occurs in the Golgi apparatus, it remains unknown how the distribution of Cfr is regulated. In the present study, we performed a mutagenic analysis of Cfr to show that two distinct regions contribute to its distribution and stability. First, the C-terminal region retains Cfr in the Golgi apparatus. Secondly, the Cfr repeats in the extracellular juxtamembrane region destabilizes Cfr passed through the Golgi apparatus. This destabilization does not depend on the cleavage and secretion of the extracellular domain of Cfr. Furthermore, we found that Cfr with a GPI (glycosylphosphatidylinositol) anchor was predominantly expressed on the cell surface in Ba/F3 cells and affected Fgf18 signalling in a similar manner to the full-length Cfr, indicating that the interaction of Cfr with Fgfs on the cell surface is important for its function in Fgf signalling. These results suggest that the expression of Cfr in the Golgi apparatus and on the plasma membrane is finely tuned through two distinct mechanisms for exhibiting different functions.

  9. Free surface simulation of a two-layer fluid by boundary element method

    Directory of Open Access Journals (Sweden)

    Weoncheol Koo

    2010-09-01

    Full Text Available A two-layer fluid with free surface is simulated in the time domain by a two-dimensional potential-based Numerical Wave Tank (NWT. The developed NWT is based on the boundary element method and a leap-frog time integration scheme. A whole domain scheme including interaction terms between two layers is applied to solve the boundary integral equation. The time histories of surface elevations on both fluid layers in the respective wave modes are verified with analytic results. The amplitude ratios of upper to lower elevation for various density ratios and water depths are also compared.

  10. Effect of electric spark pulses on surface layer structure of chromium monocrystals

    International Nuclear Information System (INIS)

    Evstyukhin, A.I.; Krapivka, N.A.; Barinov, I.P.

    1981-01-01

    Effect of electric spark pulses on the character of fracture of surface layers of chromium monocrystals during cutting in crystallographic planes (100), (110) and (111) is established. Crystallographical anisotropy of defect formation is determined and the value of defective layers during cutting in the above planes is found. A conclusion is made that cracks in chromium monocrystals of commercial grade during electric-spark cutting are formed in planes (100) and more seldom in (111) ones. A high-temperature annealing for the reduction of initial properties of chromium surface layers is suggested

  11. Absorption and reflectivity of the lithium niobate surface masked with a graphene layer

    Directory of Open Access Journals (Sweden)

    O. Salas

    2017-01-01

    Full Text Available We performed simulations of the interaction of a graphene layer with the surface of lithium niobate utilizing density functional theory and molecular dynamics at 300K and atmospheric pressure. We found that the graphene layer is physisorbed on the lithium niobate surface with an adsorption energy of -0.8205 eV/(carbon-atom. Subsequently, the energy band structure, the optical absorption and reflectivity of the new system were calculated. We found important changes in these physical properties with respect to the corresponding ones of a graphene layer and of a lithium niobate crystal.

  12. The mechanism of the surface alloy layer creation for cast steel

    Directory of Open Access Journals (Sweden)

    A. Walasek

    2012-01-01

    Full Text Available The paper presents a detailed description of the process of creation of a surface alloy layer (using high-carbon ferrochromium on the cast steel casting. The mechanism of the surface alloy layer is based on the known theories [5,6]. The proposed course of formation of the layers has been extended to decarburization stage of steel. The research included proving the presence of carbon-lean zone. The experiment included the analysis of the distribution of elements and microhardness measurement.

  13. UV and plasma treatment of thin silver layers and glass surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hluschi, J.H. [University of Applied Sciences and Arts, Von-Ossietzky-Str. 99, D-37085 Goettingen (Germany); Helmke, A. [University of Applied Sciences and Arts, Von-Ossietzky-Str. 99, D-37085 Goettingen (Germany); Roth, P. [University of Applied Sciences and Arts, Von-Ossietzky-Str. 99, D-37085 Goettingen (Germany); Boewer, R. [Interpane Glasbeschichtungsgesellschaft mbH and Co KG, Sohnreystr. 21, D-37697 Lauenfoerde (Germany); Herlitze, L. [Interpane Glasbeschichtungsgesellschaft mbH and Co KG, Sohnreystr. 21, D-37697 Lauenfoerde (Germany); Vioel, W. [University of Applied Sciences and Arts, Von-Ossietzky-Str. 99, D-37085 Goettingen (Germany)]. E-mail: vioel@hawk-hhg.de

    2006-11-10

    Thin silver layers can be modified by treatment with UV radiation or a plasma discharge. UV treatment at a wavelength of {lambda}=308 -bar nm improves the layer properties, thus leading to an enhancement of the layers IR reflectivity. For the purpose of in situ-measurement the sheet resistance is recorded during the process. Due to the Hagen-Rubens-Relation [E. Hagen, H. Rubens, Ann. Phys. 11 (1903) 873]-bar the sheet resistance is linked to the IR reflectivity of thin metal-films. A pretreatment of uncoated glass using a dielectric barrier discharge activates and cleans its surface, thus leading to an increase in adhesion of thin layers.

  14. UV and plasma treatment of thin silver layers and glass surfaces

    International Nuclear Information System (INIS)

    Hluschi, J.H.; Helmke, A.; Roth, P.; Boewer, R.; Herlitze, L.; Vioel, W.

    2006-01-01

    Thin silver layers can be modified by treatment with UV radiation or a plasma discharge. UV treatment at a wavelength of λ=308 -bar nm improves the layer properties, thus leading to an enhancement of the layers IR reflectivity. For the purpose of in situ-measurement the sheet resistance is recorded during the process. Due to the Hagen-Rubens-Relation [E. Hagen, H. Rubens, Ann. Phys. 11 (1903) 873]-bar the sheet resistance is linked to the IR reflectivity of thin metal-films. A pretreatment of uncoated glass using a dielectric barrier discharge activates and cleans its surface, thus leading to an increase in adhesion of thin layers

  15. Formation Mechanism of Surface Metamorphic Layer on Turning End Face of GH4169 Superalloy

    Directory of Open Access Journals (Sweden)

    YAO Changfeng

    2017-12-01

    Full Text Available Turning experiments and Deform-3D finite element methods were used to study the formation mechanism of surface metamorphic layer on turning GH4169 processed. The investigations were carried out by analyzing the changing of cutting force, the temperature and strain field, the residual stress, micro-hardness, microstructure, as well as the distribution of the above all along the direction of the depth under various process parameters. The results show that the surface metamorphic layer is formed due to the thermal-mechanical coupled effects on the microstructure of the material in the machining process. The cutting force, heat and strain of surface material are increased with the increase of machining intensity. Besides the higher strength of machining, the greater changes of plastic deformation, metallographic and grain deformation are acquired. In the range of processing parameters, the temperature layer is 130-200 μm,the strain layer is 100-220 μm, the residual stress layer is 80-110 μm, the depth of hardening layer is 50-80 μm, and the depth of surface metamorphic layer is 2.5-5μm.

  16. Investigation of Selective Laser Melting Surface Alloyed Aluminium Metal Matrix Dispersive Reinforced Layers

    Science.gov (United States)

    Kamburov, V. V.; Dimitrova, R. B.; Kandeva, M. K.; Sofronov, Y. P.

    2018-01-01

    The aim of the paper is to investigate the improvement of mechanical properties and in particular wear resistance of laser surface alloyed dispersive reinforced thin layers produced by selective laser melting (SLM) technology. The wear resistance investigation of aluminium matrix composite layers in the conditions of dry friction surface with abrasive particles and nanoindentation tests were carried out. The process parameters (as scan speed) and their impact on the wear resistant layers have been evaluated. The alloyed layers containing metalized SiC particles were studied by Optical and Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray microanalysis (EDX). The obtained experimental results of the laser alloyed thin layers show significant development of their wear resistance and nanohardness due to the incorporated reinforced phase of electroless nickel coated SiC particles.

  17. Surface modification of acetaminophen particles by atomic layer deposition.

    Science.gov (United States)

    Kääriäinen, Tommi O; Kemell, Marianna; Vehkamäki, Marko; Kääriäinen, Marja-Leena; Correia, Alexandra; Santos, Hélder A; Bimbo, Luis M; Hirvonen, Jouni; Hoppu, Pekka; George, Steven M; Cameron, David C; Ritala, Mikko; Leskelä, Markku

    2017-06-15

    Active pharmaceutical ingredients (APIs) are predominantly organic solid powders. Due to their bulk properties many APIs require processing to improve pharmaceutical formulation and manufacturing in the preparation for various drug dosage forms. Improved powder flow and protection of the APIs are often anticipated characteristics in pharmaceutical manufacturing. In this work, we have modified acetaminophen particles with atomic layer deposition (ALD) by conformal nanometer scale coatings in a one-step coating process. According to the results, ALD, utilizing common chemistries for Al 2 O 3 , TiO 2 and ZnO, is shown to be a promising coating method for solid pharmaceutical powders. Acetaminophen does not undergo degradation during the ALD coating process and maintains its stable polymorphic structure. Acetaminophen with nanometer scale ALD coatings shows slowed drug release. ALD TiO 2 coated acetaminophen particles show cytocompatibility whereas those coated with thicker ZnO coatings exhibit the most cytotoxicity among the ALD materials under study when assessed in vitro by their effect on intestinal Caco-2 cells. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Polyethylenimine surface layer for enhanced virus immobilization on cellulose

    Science.gov (United States)

    Tiliket, Ghania; Ladam, Guy; Nguyen, Quang Trong; Lebrun, Laurent

    2016-05-01

    Thin regenerated cellulose films are prepared by hydrolysis of cellulose acetate (CA). A polycation, namely polyethylenimine (PEI), is then adsorbed onto the films. From QCM-D analysis, PEI readily adsorbs from a 0.1% w/v solution in NaCl 0.2 M (ca. 100 ng cm-2). Further PEI adsorption steps at higher PEI concentrations induce a linear growth of the PEI films, suggesting that free adsorption sites still exist after the initial adsorption. The adsorbed PEI chains are resistant to variations of the ionic strength up to NaCl 1 M. Promisingly, the adsorption of T4D bacteriophages are 15-fold more efficient onto the PEI-treated, compared to the native regenerated cellulose films, as measured by QCM-D. This confirms the strong affinity between the negatively charged viruses and PEI, even at low PEI concentration, probably governed by strong electrostatic attractive interactions. This result explains the remarkable improvement of the affinity of medical masks for virus droplets when one of their cellulose layers was changed by two-PEI-functionalized cellulose-based filters.

  19. Where surface physics and fluid dynamics meet: rupture of an amphiphile layer by fluid flow.

    Science.gov (United States)

    Bandi, M M; Goldburg, W I; Cressman, J R; Kellay, H

    2006-03-14

    We investigate the fluctuating pattern created by a jet of fluid impingent upon an amphiphile-covered surface. This microscopically thin layer is initially covered with 50 microm floating particles so that the layer can be visualized. A vertical jet of water located below the surface and directed upward drives a hole in this layer. The hole is particle-free and is surrounded by the particle-laden amphiphile region. The jet ruptures the amphiphile layer creating a particle-free region that is surrounded by the particle-covered surface. The aim of the experiment is to understand the (fluctuating) shape of the ramified interface between the particle-laden and particle-free regions.

  20. Identification and characterization of the surface-layer protein of Clostridium tetani.

    Science.gov (United States)

    Qazi, Omar; Brailsford, Alan; Wright, Anne; Faraar, Jeremy; Campbell, Jim; Fairweather, Neil

    2007-09-01

    Many bacterial species produce a paracrystalline layer, the surface layer, which completely surrounds the exterior of the cell. In some bacteria, the surface layer is implicated in pathogenesis. Two proteins present in cell wall extracts from Clostridium tetani have been investigated and identified one of these has been unambiguously as the surface-layer protein (SLP). The gene, slpA, has been located in the genome of C. tetani E88 that encodes the SLP. The molecular mass of the protein as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis is considerably larger than that predicted from the gene; however the protein does not appear to be glycosylated. Furthermore, analysis of five C. tetani strains, including three recent clinical isolates, shows considerable variation in the sizes of the SLP.

  1. CHARACTERIZING SURFACE LAYERS IN NITINOL USING X-RAY PHOTOELECTRON SPECTROSCOPY

    Energy Technology Data Exchange (ETDEWEB)

    Christopfel, R.; Mehta, A.

    2008-01-01

    Nitinol is a shape memory alloy whose properties allow for large reversible deformations and a return to its original geometry. This nickel-titanium (NiTi) alloy has become a material used widely in the biomedical fi eld as a stent to open up collapsed arteries. Both ambient and biological conditions cause surface oxidation in these devices which in turn change its biocompatibility. The thickness of oxidized layers can cause fractures in the material if too large and can allow for penetration if too thin. Depending on the type and abundance of the chemical species on or near the surface, highly toxic metal ions can leak into the body causing cell damage or even cell death. Thus, biocompatibility of such devices is crucial. By using highly surface sensitive x-ray photoelectron spectroscopy to probe the surface of these structures, it is possible to decipher both layer composition and layer thickness. Two samples, both of which were mechanically polished, were investigated. Of the two samples, one was then exposed to a phosphate buffered saline (PBS) solution to mimic the chemical properties of blood, while the other remained unexposed. Although both samples were found to have oxide layers of appropriate thickness (on the order of a few nm), it was found that the sample exposed to the saline solution had a slightly thicker oxide layer and more signifi cantly, a phosphate layer very near the surface suggesting toxic metal components are well contained within the sample. These are considerable indications of a biocompatible device.

  2. SURFACE LAYER ACCRETION IN CONVENTIONAL AND TRANSITIONAL DISKS DRIVEN BY FAR-ULTRAVIOLET IONIZATION

    International Nuclear Information System (INIS)

    Perez-Becker, Daniel; Chiang, Eugene

    2011-01-01

    Whether protoplanetary disks accrete at observationally significant rates by the magnetorotational instability (MRI) depends on how well ionized they are. Disk surface layers ionized by stellar X-rays are susceptible to charge neutralization by small condensates, ranging from ∼0.01 μm sized grains to angstrom-sized polycyclic aromatic hydrocarbons (PAHs). Ion densities in X-ray-irradiated surfaces are so low that ambipolar diffusion weakens the MRI. Here we show that ionization by stellar far-ultraviolet (FUV) radiation enables full-blown MRI turbulence in disk surface layers. Far-UV ionization of atomic carbon and sulfur produces a plasma so dense that it is immune to ion recombination on grains and PAHs. The FUV-ionized layer, of thickness 0.01-0.1 g cm -2 , behaves in the ideal magnetohydrodynamic limit and can accrete at observationally significant rates at radii ∼> 1-10 AU. Surface layer accretion driven by FUV ionization can reproduce the trend of increasing accretion rate with increasing hole size seen in transitional disks. At radii ∼<1-10 AU, FUV-ionized surface layers cannot sustain the accretion rates generated at larger distance, and unless turbulent mixing of plasma can thicken the MRI-active layer, an additional means of transport is needed. In the case of transitional disks, it could be provided by planets.

  3. Enhanced magneto-optical imaging of internal stresses in the removed surface layer

    Science.gov (United States)

    Agalidi, Yuriy; Kozhukhar, Pavlo; Levyi, Sergii; Turbin, Dmitriy

    2015-10-01

    The paper describes a software method of reconstructing the state of the removed surface layer by visualising internal stresses in the underlying layers of the sample. Such a problem typically needs to be solved as part of forensic investigation that aims to reveal original marking of a sample with removed surface layer. For example, one may be interested in serial numbers of weapons or vehicles that had the surface layer of metal removed from the number plate. Experimental results of studying gradient internal stress fields in ferromagnetic sample using the NDI method of magneto-optical imaging (MOI) are presented. Numerical modelling results of internal stresses enclosed in the surface marking region are analysed and compared to the experimental results of magneto-optical imaging (MOI). MOI correction algorithm intended for reconstructing internal stress fields in the removed surface layer by extracting stresses retained by the underlying layers is described. Limiting ratios between parameters of a marking font are defined for the considered correction algorithm. Enhanced recognition properties for hidden stresses left by marking symbols are experimentally verified and confirmed.

  4. Preparation of lanthanum fluoride nanolayers by depositing ionic layers on silicon surface

    Energy Technology Data Exchange (ETDEWEB)

    Zhuchkov, B.S.; Tolstoi, V.P.; Murin, I.V.; Kirillov, S.N. [St. Petersburg State Univ. (Russian Federation)

    1995-11-10

    The kinetics of growth of LaF{sub 3} nanolayers on silicon surface was studied. Influences due to preparation conditions (the concentration and the pH values of the solution, the time of surface treatment, the number of cycles of ionic layer deposition) were evaluated.

  5. Macrofauna under sea ice and in the open surface layer of the Lazarev Sea, Southern Ocean

    NARCIS (Netherlands)

    Flores, Hauke; van Franeker, Jan-Andries; Cisewski, Boris; Leach, Harry; Van de Putte, Anton P.; Meesters, Erik (H. W. G.); Bathmann, Ulrich; Wolff, Wirn J.

    2011-01-01

    A new fishing gear was used to sample the macrozooplankton and micronekton community in the surface layer (0-2 m) under ice and in open water, the Surface and Under Ice Trawl (SUIT). In total, 57 quantitative hauls were conducted in the Lazarev Sea (Southern Ocean) during 3 different seasons (autumn

  6. Macrofauna under sea ice and in the open surface layer of the Lazarev Sea, Southern Ocean

    NARCIS (Netherlands)

    Florentino De Souza Silva, A.P.; Franeker, van J.A.; Cisewski, B.; Leach, H.; Putte, van de A.P.; Meesters, H.W.G.; Bathmann, U.; Wolff, W.J.

    2011-01-01

    A new fishing gear was used to sample the macrozooplankton and micronekton community in the surface layer (0–2 m) under ice and in open water, the Surface and Under Ice Trawl (SUIT). In total, 57 quantitative hauls were conducted in the Lazarev Sea (Southern Ocean) during 3 different seasons (autumn

  7. CONCENTRATION DEPENDENCE OF STERN LAYER CAPACITANCES AND SURFACE EQUILIBRIUM CONSTANTS IN SILICA-BASED NANOFLUIDIC CHANNELS

    DEFF Research Database (Denmark)

    Andersen, Mathias Bækbo; Frey, J.; Bruus, Henrik

    2010-01-01

    ]. The current models used to describe surface phenomena in nanofluidics can differ by orders of magnitude from experimentally measured values [2]. To mitigate the discrepancies, we hypothesize that the Stern-layer capacitance Cs and the surface equilibrium constants pKa, vary with the composition of the solid...

  8. Measuring air layer volumes retained by submerged floating-ferns Salvinia and biomimetic superhydrophobic surfaces

    Directory of Open Access Journals (Sweden)

    Matthias J. Mayser

    2014-06-01

    Full Text Available Some plants and animals feature superhydrophobic surfaces capable of retaining a layer of air when submerged under water. Long-term air retaining surfaces (Salvinia-effect are of high interest for biomimetic applications like drag reduction in ship coatings of up to 30%. Here we present a novel method for measuring air volumes and air loss under water. We recorded the buoyancy force of the air layer on leaf surfaces of four different Salvinia species and on one biomimetic surface using a highly sensitive custom made strain gauge force transducer setup. The volume of air held by a surface was quantified by comparing the buoyancy force of the specimen with and then without an air layer. Air volumes retained by the Salvinia-surfaces ranged between 0.15 and 1 L/m2 depending on differences in surface architecture. We verified the precision of the method by comparing the measured air volumes with theoretical volume calculations and could find a good agreement between both values. In this context we present techniques to calculate air volumes on surfaces with complex microstructures. The introduced method also allows to measure decrease or increase of air layers with high accuracy in real-time to understand dynamic processes.

  9. Stability of underpotentially deposited Ag layers on a Au(111) surface studied by surface X-ray scattering

    OpenAIRE

    Kondo, Toshihiro; Takakusagi, Satoru; Uosaki, Kohei

    2009-01-01

    Stability of underpotentially deposited (upd) Ag layers on Au(111) surface was investigated by surface X-ray scattering (SXS). While the complete pseudomorphic Ag bilayer on Au(111) surface obtained by upd at 10 mV (vs. Ag/Ag+) was maintained its structure even after the circuit was disconnected and the surface was exposed to ambient atmosphere, the pseudomorphic Ag monolayer obtained by upd at 50 mV was converted to a partial bilayer with the coverage of 0.66 ML and 0.46 ML for the 1st and 2...

  10. Surface crack formation on rails at grinding induced martensite white etching layers

    DEFF Research Database (Denmark)

    Rasmussen, Carsten Jørn; Fæster, Søren; Dhar, Somrita

    2017-01-01

    The connection between profile grinding of rails, martensite surface layers and crack initiation has been investigated using visual inspection, optical microscopy and 3D X-ray computerized tomography. Newly grinded rails were extracted and found to be covered by a continuous surface layer...... of martensite with varying thickness formed by the grinding process. Worn R350HT and R200 rails were extracted from the Danish rail network as they had transverse bands resembling grinding marks on the running surface. The transverse bands were shown to consist of martensite which had extensive crack formation...

  11. Problems of surface morphology and layer deposition during plasma etching processes. 2

    International Nuclear Information System (INIS)

    Tiller, H.-J.; Krausse, J.; Voigt, R.

    1982-01-01

    The plasma etching of Si in CF 4 -, CF 4 /O 2 - and CF 4 /H 2 plasmas was investigated in dependence on the etching gas, the plasma conditions (pressure, power density) and etching time in different reactors. A roughening of the surface and the formation of a 'semi-amorphous' surface layer with a powder-like morphology was detected by TEM-and RHEED methods. It is supposed that the surface layer has a fundamental consequence as an intermediate state in the etching mechanism. (author)

  12. Layer-by-layer generation of PEG-based regenerable immunosensing surfaces for small-sized analytes.

    Science.gov (United States)

    Huebner, Maria; Ben Haddada, Maroua; Méthivier, Christophe; Niessner, Reinhard; Knopp, Dietmar; Boujday, Souhir

    2015-05-15

    Small molecules (haptens) like pharmaceuticals or peptides can serve as targets for antibody binding in competitive immunoassay-based flow-through assays. In this work, a strategy for preparing polyethylene glycol (PEG) coatings for subsequent hapten immobilization on glass-type silica surfaces is presented and characterized in detail. Two substrates bearing terminal silanol groups were utilized, a glass slide and a silicon wafer. First, surfaces were thoroughly cleaned and pretreated to generate additional silanol groups. Then, a silane layer with terminal epoxy groups was created using 3-glycidyloxypropyltrimethoxysilane (GOPTS). Epoxy groups were used to bind a layer of diamino-poly(ethylene glycol) (DAPEG) with terminal amino groups. Finally, the low molecular weight compound diclofenac was bound to the surface to be used as model ligand for competitive biosensing of haptens. The elementary steps were characterized using atomic force microscopy (AFM), water contact angle measurement, grazing-angle attenuated total reflection (GA-ATR) FT-IR spectroscopy, and X-ray photoelectron spectroscopy (XPS). The data collected using these techniques have confirmed the successive grafting of the molecular species, evidencing, that homogeneous monolayers were created on the silica surfaces and validated the proposed mechanism of functionalization. The resulting surfaces were used to investigate polyclonal anti-diclofenac antibodies recognition and reversibility using quartz crystal microbalance with dissipation (QCM-D) measurements or an automated flow-through immunoassay with chemiluminescence (CL) read-out. For both techniques, recognition and reversibility of the antibody binding were observed. The stability of sensors over time was also assessed and no decrease in CL response was observed upon 14 days in aqueous solution. The herein presented strategy for surface functionalization can be used in the future as reproducible and reusable universal platform for hapten

  13. Surface layer composition of titania produced by various methods. The change of layer state under illumination

    International Nuclear Information System (INIS)

    Zakharenko, V; Daibova, E; Zmeeva, O; Kosova, N

    2016-01-01

    The comparative analysis of experimental data over titanium dioxide powders prepared by various ways under ambient air is carried out. The results over TiO 2 prepared by high-temperature heating of anatase, produced by burning of titanium micro particles and grinding of rutile crystal are used for that comparison. Water and carbon dioxide were the main products released from the surface of the titania powders. It was found that under UV irradiation absorbed by titania, in absent oxygen, water effectively reacts with lattice oxygen of titanium dioxide. (paper)

  14. Authority, Academic Discourse and Ideology in the ESL Writing Class: An ESL teacher’s experience

    Directory of Open Access Journals (Sweden)

    Aseel Kanakri

    2015-11-01

    Full Text Available This paper describes an ESL teachers’ perspective on teaching ESL writing to advanced second language learners reflecting on her experience as an ESL teachers drawing on the students’ responses to survey questions. It shows that writing in English as a Second language has political, cultural, and historical aspects since the “nature and functions of discourse, audience, and persuasive appeals often differ across linguistic, cultural, and educational contexts” In addition, acquiring the discourse proprieties is challenging because they represent culturally bound, conventionalized, and abstract characteristics of academic prose that are frequently absent in written discourse in rhetorical traditions other than the English dominant educational environments. ESL teachers should get the awareness of the needs and challenges that the face and understand the linguistic, cultural, and educational background they are coming from in order to help them overcome these challenges which also should dictate the instructional pedagogies, curriculum and assessment. Keywords: academic discourse, ESL writing, teacher’s perspective, ideology

  15. Thermocouple Rakes for Measuring Boundary Layer Flows Extremely Close to Surface

    Science.gov (United States)

    Hwang, Danny P.; Fralick, Gustave C.; Martin, Lisa C.; Blaha, Charles A.

    2001-01-01

    Of vital interest to aerodynamic researchers is precise knowledge of the flow velocity profile next to the surface. This information is needed for turbulence model development and the calculation of viscous shear force. Though many instruments can determine the flow velocity profile near the surface, none of them can make measurements closer than approximately 0.01 in. from the surface. The thermocouple boundary-layer rake can measure much closer to the surface than conventional instruments can, such as a total pressure boundary layer rake, hot wire, or hot film. By embedding the sensors (thermocouples) in the region where the velocity is equivalent to the velocity ahead of a constant thickness strut, the boundary-layer flow profile can be obtained. The present device fabricated at the NASA Glenn Research Center microsystem clean room has a heater made of platinum and thermocouples made of platinum and gold. Equal numbers of thermocouples are placed both upstream and downstream of the heater, so that the voltage generated by each pair at the same distance from the surface is indicative of the difference in temperature between the upstream and downstream thermocouple locations. This voltage differential is a function of the flow velocity, and like the conventional total pressure rake, it can provide the velocity profile. In order to measure flow extremely close to the surface, the strut is made of fused quartz with extremely low heat conductivity. A large size thermocouple boundary layer rake is shown in the following photo. The latest medium size sensors already provide smooth velocity profiles well into the boundary layer, as close as 0.0025 in. from the surface. This is about 4 times closer to the surface than the previously used total pressure rakes. This device also has the advantage of providing the flow profile of separated flow and also it is possible to measure simultaneous turbulence levels within the boundary layer.

  16. Steady Boundary Layer Disturbances Created By Two-Dimensional Surface Ripples

    Science.gov (United States)

    Kuester, Matthew

    2017-11-01

    Multiple experiments have shown that surface roughness can enhance the growth of Tollmien-Schlichting (T-S) waves in a laminar boundary layer. One of the common observations from these studies is a ``wall displacement'' effect, where the boundary layer profile shape remains relatively unchanged, but the origin of the profile pushes away from the wall. The objective of this work is to calculate the steady velocity field (including this wall displacement) of a laminar boundary layer over a surface with small, 2D surface ripples. The velocity field is a combination of a Blasius boundary layer and multiple disturbance modes, calculated using the linearized Navier-Stokes equations. The method of multiple scales is used to include non-parallel boundary layer effects of O (Rδ- 1) ; the non-parallel terms are necessary, because a wall displacement is mathematically inconsistent with a parallel boundary layer assumption. This technique is used to calculate the steady velocity field over ripples of varying height and wavelength, including cases where a separation bubble forms on the leeward side of the ripple. In future work, the steady velocity field will be the input for stability calculations, which will quantify the growth of T-S waves over rough surfaces. The author would like to acknowledge the support of the Kevin T. Crofton Aerospace & Ocean Engineering Department at Virginia Tech.

  17. Self-Assembled Layering of Magnetic Nanoparticles in a Ferrofluid on Silicon Surfaces.

    Science.gov (United States)

    Theis-Bröhl, Katharina; Vreeland, Erika C; Gomez, Andrew; Huber, Dale L; Saini, Apurve; Wolff, Max; Maranville, Brian B; Brok, Erik; Krycka, Kathryn L; Dura, Joseph A; Borchers, Julie A

    2018-02-07

    This article describes the three-dimensional self-assembly of monodisperse colloidal magnetite nanoparticles (NPs) from a dilute water-based ferrofluid onto a silicon surface and the dependence of the resultant magnetic structure on the applied field. The NPs assemble into close-packed layers on the surface followed by more loosely packed ones. The magnetic field-dependent magnetization of the individual NP layers depends on both the rotational freedom of the layer and the magnetization of the adjacent layers. For layers in which the NPs are more free to rotate, the easy axis of the NP can readily orient along the field direction. In more dense packing, free rotation of the NPs is hampered, and the NP ensembles likely build up quasi-domain states to minimize energy, which leads to lower magnetization in those layers. Detailed analysis of polarized neutron reflectometry data together with model calculations of the arrangement of the NPs within the layers and input from small-angle scattering measurements provide full characterization of the core/shell NP dimensions, degree of chaining, arrangement of the NPs within the different layers, and magnetization depth profile.

  18. Diffusion of C and Cr During Creation of Surface Layer on Cast Steel Casting

    Directory of Open Access Journals (Sweden)

    Szajnar J.

    2014-10-01

    Full Text Available In paper a method of improvement in utility properties of unalloyed cast steel casting in result of diffusion of C and Cr in process of creation of surface layer is presented. The aim of paper was determination of diffusion range of basic elements of alloyed surface layer. Moreover a quantitative analysis of carbides phase strengthens alloyed surface layer of casting was carried out. The results of studies shown that important factors of surface layer creation are maximal temperature Tmax on granular insert – cast steel boundary dependent of pouring temperature, granularity Zw of Fe-Cr-C alloy insert and thickness of casting wall gśo. On the basis of obtained results was affirmed that with increase of thickness of casting wall increases range of diffusion in solid state in Fe-Cr-C grains and in liquid state. Moreover the range of Tmax = 13001500oC favours creation of the proper alloyed surface layers on cast steel.

  19. Surfactant-free carnauba wax dispersion and its use for layer-by-layer assembled protective surface coatings on wood

    Energy Technology Data Exchange (ETDEWEB)

    Lozhechnikova, Alina [Department of Forest Products Technology, School of Chemical Technology, Aalto University, P.O. Box 16300, FI-00076, Aalto (Finland); Bellanger, Hervé; Michen, Benjamin; Burgert, Ingo [Institute for Building Materials (IfB), Wood Materials Science, ETH Zürich, Stefano-Franscini-Platz 3, 8093 Zürich (Switzerland); Applied Wood Materials Laboratory, Empa − Swiss Federal Laboratories for Material Testing and Research, 8600 Dübendorf (Switzerland); Österberg, Monika, E-mail: monika.osterberg@aalto.fi [Department of Forest Products Technology, School of Chemical Technology, Aalto University, P.O. Box 16300, FI-00076, Aalto (Finland)

    2017-02-28

    Highlights: • A facile sonication route to produce aqueous wax dispersions is developed. • The wax dispersion is naturally stable and free of surfactants or stabilizers. • Wax and ZnO particles are coated onto wood using layer-by-layer assembly. • The coating brings superhydrophobicity while preserving moisture buffering. • ZnO improves the color stability of wood to UV light. - Abstract: Protection from liquid water and UV radiation are equally important, and a sophisticated approach is needed when developing surface coatings that preserve the natural and well-appreciated aesthetic appearance of wood. In order to prevent degradation and prolong the service life of timber, a protective coating was assembled using carnauba wax particles and zinc oxide nanoparticles via layer-by-layer deposition in water. For this purpose, a facile sonication route was developed to produce aqueous wax dispersion without any surfactants or stabilizers. The suspension was stable above pH 4 due to the electrostatic repulsion between the negatively charged wax particles. The particle size could be controlled by the initial wax concentration with average particle sizes ranging from 260 to 360 nm for 1 and 10 g/L, respectively. The deposition of wax particles onto the surface of spruce wood introduced additional roughness to the wood surface at micron level, while zinc oxide provided nano roughness and UV-absorbing properties. In addition to making wood superhydrophobic, this novel multilayer coating enhanced the natural moisture buffering capability of spruce. Moreover, wood surfaces prepared in this fashion showed a significant reduction in color change after exposure to UV light. A degradation of the wax through photocatalytic activity of the ZnO particles was measured by FTIR, indicating that further studies are required to achieve long-term stability. Nevertheless, the developed coating showed a unique combination of superhydrophobicity and excellent moisture buffering

  20. Hard Coat Layers by PE-CVD Process for the Top Surface of Touch Panel

    International Nuclear Information System (INIS)

    Okunishi, T; Sato, N; Yazawa, K

    2013-01-01

    In order to protect surface from damages, the high pencil hardness and the high abrasion resistance are required for the hard coat layers on polyethylene telephthalate (PET) films for the application of touch panel surface. We have already found that the UV-curing-hard-coat-polymer (UHP) coated PET films show the poor abrasion resistance, while they have the high pencil hardness. It reveals that the abrasion resistance of hard coat layers of the UHP is not simply dependent on the pencil hardness. In this work, we have studied to improve the abrasion resistance of SiOC films as hard coat layers, which were formed by PE-CVD process on UHP coated PET. The abrasion resistance was evaluated by Taber abrasion test. PE-CVD hard coat layers which formed on UHP coater PET films have showed the better abrasion resistance and have the possibility of substitution to the thin glass sheets for touch panel application.

  1. Noncontact Quantification of Topography of Anterior Corneal Surface and Bowman's Layer With High-Speed OCT.

    Science.gov (United States)

    Matalia, Himanshu; Francis, Mathew; Gangil, Tarun; Chandapura, Rachana S; Kurian, Mathew; Shetty, Rohit; Nelson, Everette Jacob Remington; Sinha Roy, Abhijit

    2017-05-01

    To quantify keratometry and wavefront aberration of the anterior corneal surface and epithelium-Bowman's layer interface using anterior segment optical coherence tomography (OCT). Twenty-five normal eyes and 25 eyes with keratoconus were retrospectively analyzed. The anterior corneal edge and epithelium-Bowman's layer interface were segmented from 12 distortion-corrected OCT B-scans. Axial tangential curvatures and wavefront aberration were calculated by ray tracing and 6th order Zernike analyses. All eyes underwent simultaneous imaging with Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany). The Pentacam elevation data were used for aberration analyses using the same ray-tracing method. The paired t test was used to compare the variables. In normal eyes, mean steep axis and maximum keratometry of OCT of the anterior corneal surface and epithelium-Bowman's layer interface were significantly greater than the same of the Pentacam anterior corneal surface (P OCT surfaces was greater than the same of the Pentacam surface by a factor of 4. In eyes with keratoconus, mean steep axis and maximum keratometry of the OCT epithelium-Bowman's layer interface was the greatest (P OCT epithelium-Bowman's layer interface was the greatest (P OCT epithelium-Bowman's layer interface were significantly greater than those of the Pentacam anterior corneal surface. A noncontact method to quantify the topography and aberrations of corneal surfaces with OCT was presented. OCT measurements yielded greater curvature and aberrations than Pentacam in both normal and keratoconic eyes. [J Refract Surg. 2017;33(5):330-336.]. Copyright 2017, SLACK Incorporated.

  2. Study on dynamic deformation synchronized measurement technology of double-layer liquid surfaces

    Science.gov (United States)

    Tang, Huiying; Dong, Huimin; Liu, Zhanwei

    2017-11-01

    Accurate measurement of the dynamic deformation of double-layer liquid surfaces plays an important role in many fields, such as fluid mechanics, biomechanics, petrochemical industry and aerospace engineering. It is difficult to measure dynamic deformation of double-layer liquid surfaces synchronously for traditional methods. In this paper, a novel and effective method for full-field static and dynamic deformation measurement of double-layer liquid surfaces has been developed, that is wavefront distortion of double-wavelength transmission light with geometric phase analysis (GPA) method. Double wavelength lattice patterns used here are produced by two techniques, one is by double wavelength laser, and the other is by liquid crystal display (LCD). The techniques combine the characteristics such as high transparency, low reflectivity and fluidity of liquid. Two color lattice patterns produced by laser and LCD were adjusted at a certain angle through the tested double-layer liquid surfaces simultaneously. On the basis of the refractive indexes difference of two transmitted lights, the double-layer liquid surfaces were decoupled with GPA method. Combined with the derived relationship between phase variation of transmission-lattice patterns and out-of plane heights of two surfaces, as well as considering the height curves of the liquid level, the double-layer liquid surfaces can be reconstructed successfully. Compared with the traditional measurement method, the developed method not only has the common advantages of the optical measurement methods, such as high-precision, full-field and non-contact, but also simple, low cost and easy to set up.

  3. Interfacial layers from the protein HFBII hydrophobin: dynamic surface tension, dilatational elasticity and relaxation times.

    Science.gov (United States)

    Alexandrov, Nikola A; Marinova, Krastanka G; Gurkov, Theodor D; Danov, Krassimir D; Kralchevsky, Peter A; Stoyanov, Simeon D; Blijdenstein, Theodorus B J; Arnaudov, Luben N; Pelan, Eddie G; Lips, Alex

    2012-06-15

    The pendant-drop method (with drop-shape analysis) and Langmuir trough are applied to investigate the characteristic relaxation times and elasticity of interfacial layers from the protein HFBII hydrophobin. Such layers undergo a transition from fluid to elastic solid films. The transition is detected as an increase in the error of the fit of the pendant-drop profile by means of the Laplace equation of capillarity. The relaxation of surface tension after interfacial expansion follows an exponential-decay law, which indicates adsorption kinetics under barrier control. The experimental data for the relaxation time suggest that the adsorption rate is determined by the balance of two opposing factors: (i) the barrier to detachment of protein molecules from bulk aggregates and (ii) the attraction of the detached molecules by the adsorption layer due to the hydrophobic surface force. The hydrophobic attraction can explain why a greater surface coverage leads to a faster adsorption. The relaxation of surface tension after interfacial compression follows a different, square-root law. Such behavior can be attributed to surface diffusion of adsorbed protein molecules that are condensing at the periphery of interfacial protein aggregates. The surface dilatational elasticity, E, is determined in experiments on quick expansion or compression of the interfacial protein layers. At lower surface pressures (<11 mN/m) the experiments on expansion, compression and oscillations give close values of E that are increasing with the rise of surface pressure. At higher surface pressures, E exhibits the opposite tendency and the data are scattered. The latter behavior can be explained with a two-dimensional condensation of adsorbed protein molecules at the higher surface pressures. The results could be important for the understanding and control of dynamic processes in foams and emulsions stabilized by hydrophobins, as well as for the modification of solid surfaces by adsorption of such

  4. Formation of a nanocrystalline layer on the surface of stone wool fibers

    DEFF Research Database (Denmark)

    Yue, Yuanzheng; Korsgaard, Martin; Kirkegaard, Lise Frank

    2009-01-01

    In the present paper, we report a simple approach for creating a nanocrystalline layer on the surface of stone wool fibers (SWFs) with a basalt-like composition. The approach is based on a preoxidation process of the SWFs in atmospheric air at a temperature around the glass transition temperature....... The nanocrystalline layer plays a significant role in enhancing the high-temperature stability of the SWFs....

  5. Heat-resistant organic molecular layer as a joint interface for metal reduction on plastics surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sang, Jing [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Aisawa, Sumio, E-mail: aisawa@iwate-u.ac.jp [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Hirahara, Hidetoshi [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Kudo, Takahiro [Sulfur Chemical Institute, 210, Collabo MIU, 4-3-5, Ueda, Morioka 020-0066 (Japan); Mori, Kunio [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Sulfur Chemical Institute, 210, Collabo MIU, 4-3-5, Ueda, Morioka 020-0066 (Japan)

    2016-04-15

    Graphical abstract: - Highlights: • In situ adsorption behaviors of TES on PA6 surface were clarified by QCM. • Highest adsorption of TES on PA6 was obtained in pH 3 and 0.1 M solution. • Molecular layers of TES with uniform structures were prepared on PA6 surface. • TES layer improved PA6 local heat resistance from 150 °C to 230 °C. • TES molecular layer successfully reduced Ag ion to Ag{sup 0}. - Abstract: Heat-resistant organic molecular layers have been fabricated by triazine-based silane coupling agent for metal reduction on plastic surfaces using adsorption method. These molecular layers were used as an interfacial layer between polyamide (PA6) and metal solution to reduce Ag{sup +} ion to Ag{sup 0}. The interfacial behaviors of triazine molecular layer at the interfaces between PA6 and Ag solution were investigated using quartz crystal microbalance (QCM). The kinetics of molecular adsorption on PA6 was investigated by using triazine-based silane coupling agent solutions at different pH and concentration. X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), and local nano thermal analysis were employed to characterize the surfaces and interfaces. The nano thermal analysis results show that molecular layers of triazine-based silane coupling agent greatly improved heat resistance of PA6 resin from 170 °C up to 230 °C. This research developed an in-depth insight for molecular behaviors of triazine-based silane coupling agent at the PA6 and Ag solution interfaces and should be of significant value for interfacial research between plastics and metal solution in plating industry.

  6. Designing Websites for ESL Learners: A Usability Testing Study

    Science.gov (United States)

    Liu, Min; Traphagan, Tomoko; Huh, Jin; Koh, Young Ihn; Choi, Gilok; McGregor, Allison

    2008-01-01

    The purpose of this paper is to report on a usability study for ESL websites conducted to gain insights from learners of English as a second language (ESL) as they interacted with specific sites. Five carefully selected ESL sites were tested by 10 different users generating a total of fifty testing sessions. Two major research questions guided the…

  7. Study of surface plasmon resonance of Au nanoparticles coated with dielectric layers

    Science.gov (United States)

    He, Jia-Yu; Huang, Chan-yan; Dai, Ning; Zhu, Da-ming

    2011-08-01

    In this work, atomic layer deposition (ALD) was used to deposit different thickness layers of Al2O3 on Au nanoparticles fabricated by thermal annealing of Au thin films. The effects of the Au-coated Al2O3 layer thickness variation to local surface plasmon resonance (LSPR) in gold (Au) nanoparticles was investigated using transmission surface plasmon resonance (T-SPR) spectroscopy. Thermal annealing of ultrathin films of Au sputtered on transparent substrates can get a dispersed metal particles system which exhibit transmission spectra showing an extinction band attributed to localized surface plasmon resonance (LSPR). The particles prepared by thermal annealing are much more like elliptical rather than sphere. The dielectric medium layer Al2O3 was deposited on these Au particles with the thickness from few nanometers to tens of nanometers by ALD. We found that All the LSPR peak positions of particles on different substrates red shifted as the thickness of deposition layer increase, but the LSPR red-shift effect of particles on alumina substrate was much more remarkable than particles on glass substrate. The results in this paper show that it is a very continent method to manipulate LSPR position which is a profound useful effect in solar cell application by controlling the deposition layer thickness on particles prepared by thermal annealing on suitable substrate.

  8. Relevance of sub-surface chip layers for the lifetime of magnetically trapped atoms

    DEFF Research Database (Denmark)

    Zhang, H. B.; Henkel, C; Haller, E.

    2005-01-01

    on the thickness of that layer, as long as the layers below have a much smaller conductivity; essentially the same magnetic noise would be obtained with a metallic membrane suspended in vacuum. Based on our theory we give general scaling laws of how to reduce the effect of surface magnetic noise on the trapped...... measurements where the center of a side guide trap is laterally shifted with respect to the current carrying wire using additional bias fields. Comparing the experiment to theory, we find a fair agreement and demonstrate that for a chip whose topmost layer is metallic, the magnetic noise depends essentially...

  9. Investigation of mechanical characteristics of composite surface layers using materials with thermoelastic properties

    Science.gov (United States)

    Rusinov, P. O.; Blednova, Zh. M.; Borovets, O. I.

    2017-12-01

    We developed the formation technology of the steel-layer with elastic phase transformations-ceramic wear-resistant layer composition by means of high-velocity oxygen fuel spraying (HVOF) in the protective medium of mechanically activated powders TiNiCu and cBN-Co-Mo. We also determined optimal processing parameters. We revealed regularities in the formation of the nanoscale state of the composition on the basis of complex X-ray diffraction and electron-microscopic studies. We carried out tests of steel 1045 with surface-modified layers TiNiCu + cBN-Co-Mo on friction wear, which showed an increase in wear resistance.

  10. Removing device and method for radiation-contaminated concrete surface layer

    International Nuclear Information System (INIS)

    Ida, Kiyoshi.

    1996-01-01

    When a radiation-contaminated concrete surface layer is crushed, peeled or melted, and the products generated by the procedures are captured by sucking, the activity of the products is measured. It is judged whether the result is higher than a predetermined level or not, and when the activity is lowered to a predetermined level or less, the portion to be crushed, peeled or melted is moved and the radiation-contaminated concrete surface layer is thus successively removed. In the device of the present invention, microwave energy, millimeter wave energy, or AC arc plasma is used as an energy irradiation means. With such procedures, the contaminated concrete surface layer can be removed efficiently with neither more nor less. (T.M.)

  11. Structure of the surface layer protein of the outer membrane of Spirillum serpens

    Energy Technology Data Exchange (ETDEWEB)

    Glaeser, R.M.; Chiu, W.; Grano, D.

    1979-01-01

    The outer membrane of the Gram negative bacterium, Spirillum serpens VHA, possesses an ordered surface-layer protein. A morphological model of this protein is proposed on the basis of electron micrographs that have been obtained of unstained, hydrated specimens as well as of negatively stained specimens. The molecular weight of the protein monomer in this model is consistent with the surface-layer protein molecular weight obtained by gel electrophoresis and estimated to be 140,000. In addition, gel electrophoresis reveals the presence of proteins of MW approx. = 35,000 and MW approx. = 78,000, which remain associated with the outer membrane under conditions where the ordered surface-layer protein is released in soluble form.

  12. Manufacture of silicon-based devices having disordered sulfur-doped surface layers

    Science.gov (United States)

    Carey, III, James Edward; Mazur, Eric

    2008-04-08

    The present invention provides methods of fabricating a radiation-absorbing semiconductor wafer by irradiating at least one surface location of a silicon substrate, e.g., an n-doped crystalline silicon, by a plurality of temporally short laser pulses, e.g., femtosecond pulses, while exposing that location to a substance, e.g., SF.sub.6, having an electron-donating constituent so as to generate a substantially disordered surface layer (i.e., a microstructured layer) that incorporates a concentration of that electron-donating constituent, e.g., sulfur. The substrate is also annealed at an elevated temperature and for a duration selected to enhance the charge carrier density in the surface layer. For example, the substrate can be annealed at a temperature in a range of about 700 K to about 900 K.

  13. Surfactant-free carnauba wax dispersion and its use for layer-by-layer assembled protective surface coatings on wood

    Science.gov (United States)

    Lozhechnikova, Alina; Bellanger, Hervé; Michen, Benjamin; Burgert, Ingo; Österberg, Monika

    2017-02-01

    Protection from liquid water and UV radiation are equally important, and a sophisticated approach is needed when developing surface coatings that preserve the natural and well-appreciated aesthetic appearance of wood. In order to prevent degradation and prolong the service life of timber, a protective coating was assembled using carnauba wax particles and zinc oxide nanoparticles via layer-by-layer deposition in water. For this purpose, a facile sonication route was developed to produce aqueous wax dispersion without any surfactants or stabilizers. The suspension was stable above pH 4 due to the electrostatic repulsion between the negatively charged wax particles. The particle size could be controlled by the initial wax concentration with average particle sizes ranging from 260 to 360 nm for 1 and 10 g/L, respectively. The deposition of wax particles onto the surface of spruce wood introduced additional roughness to the wood surface at micron level, while zinc oxide provided nano roughness and UV-absorbing properties. In addition to making wood superhydrophobic, this novel multilayer coating enhanced the natural moisture buffering capability of spruce. Moreover, wood surfaces prepared in this fashion showed a significant reduction in color change after exposure to UV light. A degradation of the wax through photocatalytic activity of the ZnO particles was measured by FTIR, indicating that further studies are required to achieve long-term stability. Nevertheless, the developed coating showed a unique combination of superhydrophobicity and excellent moisture buffering ability and some UV protection, all achieved using an environmentally friendly coating process, which is beneficial to retain the natural appearance of wood and improve indoor air quality and comfort.

  14. Reduction of microbial contamination on the surfaces of layer houses using slightly acidic electrolyzed water.

    Science.gov (United States)

    Ni, L; Cao, W; Zheng, W C; Zhang, Q; Li, B M

    2015-11-01

    The objective of this study was to evaluate the effectiveness of slightly acidic electrolyzed water (SAEW) in reducing pathogens on pure cultures and on cotton fabric surfaces in the presence of organic matter and estimate its efficacy in comparison with povidone iodine solution for reducing pathogenic microorganisms on internal surfaces of layer houses. Pure cultures of E.coli, S.enteritidis, and S.aureus and cotton fabric surfaces inoculated with these strains were treated with SAEW in the presence of bovine serum albumin (BSA). In the absence of BSA, complete inactivation of all strains in pure cultures and on cotton fabric surfaces was observed after 2.5 and 5 min treatment with SAEW at 40 mg/L of available chlorine concentration (ACC), respectively. The bactericidal efficiency of SAEW increased with increasing ACC, but decreased with increasing BSA concentration. Then, the surfaces of the layer houses were sprayed with SAEW at 60, 80, and 100 mg/L of ACC and povidone iodine using the automated disinfection system at a rate of 110 mL/m(2), respectively. Samples from the floor, wall, feed trough, and egg conveyor belt surfaces were collected with sterile cotton swabs before and after spraying disinfection. Compared to tap water, SAEW and povidone iodine significantly reduced microbial populations on each surface of the layer houses. SAEW with 80 or 100 mg/L of ACC showed significantly higher efficacy than povidone iodine for total aerobic bacteria, staphylococci, coliforms, or yeasts and moulds on the floor and feed trough surfaces (P conveyor belt. Results suggest that SAEW exerts a higher or equivalent bactericidal efficiency for the surfaces compared to povidone iodine, and it may be used as an effective alternative for reducing microbial contamination on surfaces in layer houses. © 2015 Poultry Science Association Inc.

  15. Surface Floating 2D Bands in Layered Nonsymmorphic Semimetals: ZrSiS and Related Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Topp, Andreas; Queiroz, Raquel; Grüneis, Andreas; Müchler, Lukas; Rost, Andreas W.; Varykhalov, Andrei; Marchenko, Dmitry; Krivenkov, Maxim; Rodolakis, Fanny; McChesney, Jessica L.; Lotsch, Bettina V.; Schoop, Leslie M.; Ast, Christian R.

    2017-12-01

    In this work, we present a model of the surface states of nonsymmorphic semimetals. These are derived from surface mass terms that lift the high degeneracy imposed in the band structure by the nonsymmorphic bulk symmetries. Reflecting the reduced symmetry at the surface, the bulk bands are strongly modified. This leads to the creation of two-dimensional floating bands, which are distinct from Shockley states, quantum well states or topologically protected surface states. We focus on the layered semimetal ZrSiS to clarify the origin of its surface states. We demonstrate an excellent agreement between DFT calculations and ARPES measurements and present an effective four-band model in which similar surface bands appear. Finally, we emphasize the role of the surface chemical potential by comparing the surface density of states in samples with and without potassium coating. Our findings can be extended to related compounds and generalized to other crystals with nonsymmorphic symmetries.

  16. `Surface-Layer' momentum fluxes in nocturnal slope flows over steep terrain

    Science.gov (United States)

    Oldroyd, H. J.; Pardyjak, E.; Higgins, C. W.; Parlange, M. B.

    2017-12-01

    A common working definition for the `surface layer' is the lowest 10% of the atmospheric boundary layer (ABL) where the turbulent fluxes are essentially constant. The latter part of this definition is a critical assumption that must hold for accurate flux estimations from land-surface models, wall models, similarity theory, flux-gradient relations and bulk transfer methods. We present cases from observed momentum fluxes in nocturnal slope flows over steep (35.5 degree), alpine terrain in Val Ferret, Switzerland that satisfy the classical definitions of the surface layer and other cases where no traditional surface layer is observed. These cases broadly fall into two distinct flow regimes occurring under clear-sky conditions: (1) buoyancy-driven, `katabatic flow', characterized by an elevated velocity maximum (katabatic jet peak) and (2) `downslope winds', for which larger-scale forcing prevents formation of a katabatic jet. Velocity profiles in downslope wind cases are quite similar to logarithmic profiles typically observed over horizontal and homogeneous terrain, and the corresponding momentum fluxes roughly resemble a constant-flux surface-layer. Contrastingly, velocity profiles in the katabatic regime exhibit a jet-like shape. This jet strongly modulates the corresponding momentum fluxes, which exhibit strong gradients over the shallow katabatic layer and usually change sign near the jet peak, where the velocity gradients also change sign. However, a counter-gradient momentum flux is frequently observed near the jet peak (and sometimes at higher levels), suggesting strong non-local turbulent transport within the katabatic jet layer. We compare our observations with katabatic flow theories and observational studies over shallow-angle slopes and use co-spectral analyses to better identify and understand the non-local transport dynamics. Finally, we show that because of the counter-gradient momentum fluxes, surface layer stability and even local stability can be

  17. Tuning Tribological Performance of Layered Zirconium Phosphate Nanoplatelets in Oil by Surface and Interlayer Modifications

    Science.gov (United States)

    Han, Xiao; Yong, Huaisong; Sun, Dazhi

    2017-09-01

    Two-dimensional (2D) inorganic layered nanoplatelets exhibit superior lubricating properties in both solid states and oil dispersions. In this paper, we have systematically investigated the effects of surface and interlayer modifications on the tribological performance of layered α-zirconium phosphate (ZrP) nanoplatelets in mineral oil. The pristine layered ZrP nanoplatelets were first reacted with silanes of different alkyl chains to achieve outer surface modifications, followed by intercalation with different alkyl amines to alter the interlayer spacing. Friction and anti-wear studies on ZrP nanoplatelets with various modifications in mineral oils suggest that a longer alkyl chain on the outer surfaces along with a small increase in interlayer spacing would lead to a better tribological behavior especially under a relatively heavy load condition. Our results illustrate the ability of tuning the tribological properties of 2D layered nanoplatelets in oils by varying their surface and interlayer functionalities and would be helpful for understanding the underlying tribological mechanisms of nanolubricating oils containing 2D layered nanoplatelets. [Figure not available: see fulltext.

  18. Evidence of a Transition Layer between the Free Surface and the Bulk

    KAUST Repository

    Ogieglo, Wojciech

    2018-02-21

    The free surface, a very thin layer at the interface between polymer and air, is considered the main source of the perturbations in the properties of ultrathin polymer films, i.e., nanoconfinement effects. The structural relaxation of such a layer is decoupled from the molecular dynamics of the bulk. The free surface is, in fact, able to stay liquid even below the temperature where the polymer resides in the glassy state. Importantly, this surface layer is expected to have a very sharp interface with the underlying bulk. Here, by analyzing the penetration of n-hexane into polystyrene films, we report on the existence of a transition region, not observed by previous investigations, extending for 12 nm below the free surface. The presence of such a layer permits reconciling the behavior of interfacial layers with current models and has profound implications on the performance of ultrathin membranes. We show that the expected increase in the flux of the permeating species is actually overruled by nanoconfinement.

  19. Impact of Bay-Breeze Circulations on Surface Air Quality and Boundary Layer Export

    Science.gov (United States)

    Loughner, Christopher P.; Tzortziou, Maria; Follette-Cook, Melanie; Pickering, Kenneth E.; Goldberg, Daniel; Satam, Chinmay; Weinheimer, Andrew; Crawford, James H.; Knapp, David J.; Montzka, Denise D.; hide

    2014-01-01

    Meteorological and air-quality model simulations are analyzed alongside observations to investigate the role of the Chesapeake Bay breeze on surface air quality, pollutant transport, and boundary layer venting. A case study was conducted to understand why a particular day was the only one during an 11-day ship-based field campaign on which surface ozone was not elevated in concentration over the Chesapeake Bay relative to the closest upwind site and why high ozone concentrations were observed aloft by in situ aircraft observations. Results show that southerly winds during the overnight and early-morning hours prevented the advection of air pollutants from the Washington, D.C., and Baltimore, Maryland, metropolitan areas over the surface waters of the bay. A strong and prolonged bay breeze developed during the late morning and early afternoon along the western coastline of the bay. The strength and duration of the bay breeze allowed pollutants to converge, resulting in high concentrations locally near the bay-breeze front within the Baltimore metropolitan area, where they were then lofted to the top of the planetary boundary layer (PBL). Near the top of the PBL, these pollutants were horizontally advected to a region with lower PBL heights, resulting in pollution transport out of the boundary layer and into the free troposphere. This elevated layer of air pollution aloft was transported downwind into New England by early the following morning where it likely mixed down to the surface, affecting air quality as the boundary layer grew.

  20. Tuning Tribological Performance of Layered Zirconium Phosphate Nanoplatelets in Oil by Surface and Interlayer Modifications.

    Science.gov (United States)

    Han, Xiao; Yong, Huaisong; Sun, Dazhi

    2017-09-20

    Two-dimensional (2D) inorganic layered nanoplatelets exhibit superior lubricating properties in both solid states and oil dispersions. In this paper, we have systematically investigated the effects of surface and interlayer modifications on the tribological performance of layered α-zirconium phosphate (ZrP) nanoplatelets in mineral oil. The pristine layered ZrP nanoplatelets were first reacted with silanes of different alkyl chains to achieve outer surface modifications, followed by intercalation with different alkyl amines to alter the interlayer spacing. Friction and anti-wear studies on ZrP nanoplatelets with various modifications in mineral oils suggest that a longer alkyl chain on the outer surfaces along with a small increase in interlayer spacing would lead to a better tribological behavior especially under a relatively heavy load condition. Our results illustrate the ability of tuning the tribological properties of 2D layered nanoplatelets in oils by varying their surface and interlayer functionalities and would be helpful for understanding the underlying tribological mechanisms of nanolubricating oils containing 2D layered nanoplatelets. Graphical abstract ᅟ.

  1. Surface modification induced phase transformation and structure variation on the rapidly solidified recast layer of titanium

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Ming-Hung [Department of Mechanical Engineering and Graduate Institute of Mechanical and Precision Engineering, National Kaoshiung University of Applied Sciences, Kaoshiung 807, Taiwan (China); School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Haung, Chiung-Fang [School of Dental Technology, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Division of Family and Operative Dentistry, Department of Dentistry, Taipei Medical University Hospital, Taipei 110, Taiwan (China); Research Center for Biomedical Devices and Prototyping Production, Taipei Medical University, Taipei 110, Taiwan (China); Shyu, Shih-Shiun [Department of Dentistry, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei City 231, Taiwan (China); Chou, Yen-Ru [Research Center for Biomedical Devices and Prototyping Production, Taipei Medical University, Taipei 110, Taiwan (China); Graduate Institute of Biomedical Materials and Tissue Engineering, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Research Center for Biomedical Implants and Microsurgery Devices, Taipei Medical University, Taipei 110, Taiwan (China); Lin, Ming-Hong [Department of Mechanical Engineering and Graduate Institute of Mechanical and Precision Engineering, National Kaoshiung University of Applied Sciences, Kaoshiung 807, Taiwan (China); Peng, Pei-Wen, E-mail: apon@tmu.edu.tw [School of Dental Technology, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); and others

    2015-08-15

    In this study, neodymium-doped yttrium orthovanadate (Nd:YVO{sub 4}) as a laser source with different scanning speeds was used on biomedical Ti surface. The microstructural and biological properties of laser-modified samples were investigated by means of optical microscope, electron microscope, X-ray diffraction, surface roughness instrument, contact angle and cell cytotoxicity assay. After laser modification, the rough volcano-like recast layer with micro-/nanoporous structure and wave-like recast layer with nanoporous structure were generated on the surfaces of laser-modified samples, respectively. It was also found out that, an α → (α + rutile-TiO{sub 2}) phase transition occurred on the recast layers of laser-modified samples. The Ti surface becomes hydrophilic at a high speed laser scanning. Moreover, the cell cytotoxicity assay demonstrated that laser-modified samples did not influence the cell adhesion and proliferation behaviors of osteoblast (MG-63) cell. The laser with 50 mm/s scanning speed induced formation of rough volcano-like recast layer accompanied with micro-/nanoporous structure, which can promote cell adhesion and proliferation of MG-63 cell on Ti surface. The results indicated that the laser treatment was a potential technology to enhance the biocompatibility for titanium. - Highlights: • Laser induced the formation of recast layer with micro-/nanoporous structure on Ti. • An α → (α + rutile-TiO{sub 2}) phase transition was observed within the recast layer. • The Ti surface becomes hydrophilic at a high speed laser scanning. • Laser-modified samples exhibit good biocompatibility to osteoblast (MG-63) cell.

  2. The effect of using waste newspaper in surface layers on physical and mechanical properties of three-layer particleboard

    Directory of Open Access Journals (Sweden)

    vahid vaziri

    2017-02-01

    Full Text Available In this study, physical and mechanical properties of particleboard made from recycled newspaper in the surface layers were investigated. Coarse and fine wood chips and recycled newspaper with dimension of 0.5 × 4 cm2 were used. The variable in this research were the ratio of recycled newspaper to wood chips (at five levels; 0:100, 15:85, 30:70, 45:55, 60:40. Urea formaldehyde resin used at 10% content on dry weight basis of the wood particles and newspaper and ammonium chloride was used as a catalyst to 2% of the dry weight of adhesive. Physical and mechanical properties of panels measured according to EN Standard. The results showed that panels containing recycled newspapers at the level of 45% had the highest bending strength and modulus of elasticity. Internal bonding and screw holding strength decreased with increasing of recycled newspaper and control sample had the highest strength. Water absorption and thickness swelling increased with increasing of recycled newspaper portion. On the basis of results of this study can be concluded that particleboard containing recycled newspapers in the surface layers up to the level of 30% can be used for general purpose boards and interior fitments (including furniture for use in dry conditions.

  3. Antiferroelectric surface layers in a liquid crystal as observed by synchrotron x-ray scattering

    DEFF Research Database (Denmark)

    Gramsbergen, E. F.; de Jeu, W. H.; Als-Nielsen, Jens Aage

    1986-01-01

    The X-ray reflectivity form the surface of a liquid crystal with terminally polar (cyano substituted) molecules has been studied using a high-resolution triple-axis X-ray spectrometer in combination with a synchrotron source. It is demonstrated that at the surface of the smectic Al phase a few...... antiferroelectric double layers develop that can be distinguished from the bulk single layer structure. A model is developed that separates the electron density in a contribution from the molecular form factor, and from the structure factor of the mono- and the bilayers, respectively. It shows that (i) the first...

  4. Effectiveness of Protective Action of Coatings from Moisture Sorption into Surface Layer of Sand Moulds

    Directory of Open Access Journals (Sweden)

    Kaźnica N.

    2016-12-01

    Full Text Available The results of investigations of the sorption process of surface layers of sand moulds covered by zirconium and zirconium - graphite alcohol coatings are presented in the paper. Investigations comprised two kinds of sand grains (silica sand and reclaimed sand of moulding sand with furan resin. Tests were performed under conditions of a high relative air humidity 75 - 85% and a constant temperature within the range 28 – 33°C. To evaluate the effectiveness of coatings protective action from moisture penetration into surface layers of sand moulds gravimetric method of quantitavie moisture sorption and ultrasonic method were applied in measurements.

  5. Adhesion of oxide layer to metal-doped aluminum hydride surface: Density functional calculations

    Science.gov (United States)

    Takezawa, Tomoki; Itoi, Junichi; Kannan, Takashi

    2017-07-01

    The density functional theory (DFT) calculations were carried out to evaluate the adhesion energy of the oxide layer to the metal-doped surface of hydrogen storage material, aluminum hydride (alane, AlH3). The total energy calculations using slab model revealed that the surface doping of some metals to aluminum hydride weakens the adhesion strength of the oxide layer. The influence of titanium, iron, cobalt, and zirconium doping on adhesion strength were evaluated. Except for iron doping, the adhesion strength becomes weak by the doping.

  6. Comparison of mechanical properties of surface layers with use of nanoindentation and microindentation tests

    Directory of Open Access Journals (Sweden)

    M. Zeleňák

    2012-07-01

    Full Text Available The objective of the paper is a mutual comparison of different methods for evaluation of mechanical properties of surface layers. Mechanical properties were tested with the use of nanoindentation and microindentation tests. Different loads and constant deformation speed were used in both cases. For the evaluation of mechanical properties, the AISI 304 type Chromium-Nickel steel commonly used in mechanical engineering industry was tested. Knowledge of relations and differences between nano and micromechanical properties is necessary for understanding of mechanical processes continuously occurring in surface layers during cutting processes.

  7. Macro-carriers of plastic deformation of steel surface layers detected by digital image correlation

    Energy Technology Data Exchange (ETDEWEB)

    Kopanitsa, D. G., E-mail: kopanitsa@mail.ru; Ustinov, A. M., E-mail: artemustinov@mail.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); Potekaev, A. I., E-mail: potekaev@spti.tsu.ru [National Research Tomsk State University, 36 Lenin Ave., Tomsk, 634050 (Russian Federation); Klopotov, A. A., E-mail: klopotovaa@tsuab.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); National Research Tomsk State University, 36 Lenin Ave., Tomsk, 634050 (Russian Federation); Kopanitsa, G. D., E-mail: georgy.kopanitsa@mail.com [National Research Tomsk Polytechnic University, 30 Lenin Ave., Tomsk, 634050 (Russian Federation)

    2016-01-15

    This paper presents a study of characteristics of an evolution of deformation fields in surface layers of medium-carbon low-alloy specimens under compression. The experiments were performed on the “Universal Testing Machine 4500” using a digital stereoscopic image processing system Vic-3D. A transition between stages is reflected as deformation redistribution on the near-surface layers. Electronic microscopy shows that the structure of the steel is a mixture of pearlite and ferrite grains. A proportion of pearlite is 40% and ferrite is 60%.

  8. The effect of surface layer properties on bendability of ultra-high strength steel

    Science.gov (United States)

    Arola, Anna-Maija; Kaijalainen, Antti; Kesti, Vili

    2016-10-01

    Bendability is an important property for ultra-high strength steel because air-bending is the most common forming process for the material. In this paper the bendability of two ultra-high strength steels with similar mechanical properties but different bendability was investigated using tensile testing with optical strain measurements. The tensile tests were conducted also for specimens cut from the surface layer and the middle layer of the sheet. It was discovered that the mechanical properties of the surface of the sheet affect the bendability in great manner.

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

    International Nuclear Information System (INIS)

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

    1979-01-01

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

  10. Boundary layers of aqueous surfactant and block copolymer solutions against hydrophobic and hydrophilic solid surfaces

    International Nuclear Information System (INIS)

    Steitz, Roland; Schemmel, Sebastian; Shi Hongwei; Findenegg, Gerhard H

    2005-01-01

    The boundary layer of aqueous surfactants and amphiphilic triblock copolymers against flat solid surfaces of different degrees of hydrophobicity was investigated by neutron reflectometry (NR), grazing incidence small angle neutron scattering (GISANS) and atomic force microscopy (AFM). Solid substrates of different hydrophobicities were prepared by appropriate surface treatment or by coating silicon wafers with polymer films of different chemical natures. For substrates coated with thin films (20-30 nm) of deuterated poly(styrene) (water contact angle θ w ∼ 90), neutron reflectivity measurements on the polymer/water interface revealed a water depleted liquid boundary layer of 2-3 nm thickness and a density about 90% of the bulk water density. No pronounced depletion layer was found at the interface of water against a less hydrophobic polyelectrolyte coating (θ w ∼ 63). It is believed that the observed depletion layer at the hydrophobic polymer/water interface is a precursor of the nanobubbles which have been observed by AFM at this interface. Decoration of the polymer coatings by adsorbed layers of nonionic C m E n surfactants improves their wettability by the aqueous phase at surfactant concentrations well below the critical micellar concentration (CMC) of the surfactant. Here, GISANS experiments conducted on the system SiO 2 /C 8 E 4 /D 2 O reveal that there is no preferred lateral organization of the C 8 E 4 adsorption layers. For amphiphilic triblock copolymers (PEO-PPO-PEO) it is found that under equilibrium conditions they form solvent-swollen brushes both at the air/water and the solid/water interface. In the latter case, the brushes transform to uniform, dense layers after extensive rinsing with water and subsequent solvent evaporation. The primary adsorption layers maintain properties of the precursor brushes. In particular, their thickness scales with the number of ethylene oxide units (EO) of the block copolymer. In the case of dip-coating without

  11. Shear rheology of mixed protein adsorption layers vs their structure studied by surface force measurements.

    Science.gov (United States)

    Danov, Krassimir D; Kralchevsky, Peter A; Radulova, Gergana M; Basheva, Elka S; Stoyanov, Simeon D; Pelan, Eddie G

    2015-08-01

    The hydrophobins are proteins that form the most rigid adsorption layers at liquid interfaces in comparison with all other investigated proteins. The mixing of hydrophobin HFBII with other conventional proteins is expected to reduce the surface shear elasticity and viscosity, E(sh) and η(sh), proportional to the fraction of the conventional protein. However, the experiments show that the effect of mixing can be rather different depending on the nature of the additive. If the additive is a globular protein, like β-lactoglobulin and ovalbumin, the surface rigidity is preserved, and even enhanced. The experiments with separate foam films indicate that this is due to the formation of a bilayer structure at the air/water interface. The more hydrophobic HFBII forms the upper layer adjacent to the air phase, whereas the conventional globular protein forms the lower layer that faces the water phase. Thus, the elastic network formed by the adsorbed hydrophobin remains intact, and even reinforced by the adjacent layer of globular protein. In contrast, the addition of the disordered protein β-casein leads to softening of the HFBII adsorption layer. Similar (an even stronger) effect is produced by the nonionic surfactant Tween 20. This can be explained with the penetration of the hydrophobic tails of β-casein and Tween 20 between the HFBII molecules at the interface, which breaks the integrity of the hydrophobin interfacial elastic network. The analyzed experimental data for the surface shear rheology of various protein adsorption layers comply with a viscoelastic thixotropic model, which allows one to determine E(sh) and η(sh) from the measured storage and loss moduli, G' and G″. The results could contribute for quantitative characterization and deeper understanding of the factors that control the surface rigidity of protein adsorption layers with potential application for the creation of stable foams and emulsions with fine bubbles or droplets. Copyright © 2014

  12. Heat transfer control in a plane magnetic fluid layer with a free surface

    International Nuclear Information System (INIS)

    Bashtovoi, V.G.; Pogirnitskaya, S.G.; Reks, A.G.

    1993-01-01

    The heat transfer mechanisms that are specific to a magnetic liquid have been already investigated extensively. The high sensitivity of the free magnetic liquid surface to the external magnetic field introduces a new feature into the heat transfer process. In the present work, the authors have investigated the possibility of controlling the heat transfer through the phenomenon of magnetic liquid surface instability in a uniform magnetic field. The conditions for heat transfer through a chamber, partially filled with a magnetic liquid, are governed by the characteristics of the free liquid surface and by its stability and development in the supercritical magnetic fields. The authors consider a model two-dimensional problem of heat transfer through a two-layer medium consisting of horizontally situated immiscible layers of magnetic and nonmagnetic liquids with given thermal conductivities. In the absence of an external magnetic field, the interface of the liquids represents a plane surface. In fields which exceed the critical magnitude, the interface is deformed along the wave. As the field intensity is increased, the amplitude of interface distortion becomes larger. The two-dimensional shape of the free magnetic liquid surface may be realized experimentally using two plane layers of magnetic and nonmagnetic liquids in a uniform magnetic field tangent to the interface of the component layers. 7 refs., 9 figs

  13. Permeation Properties and Pore Structure of Surface Layer of Fly Ash Concrete.

    Science.gov (United States)

    Liu, Jun; Qiu, Qiwen; Xing, Feng; Pan, Dong

    2014-05-30

    This paper presents an experimental study on the nature of permeation properties and pore structure of concrete surface layers containing fly ash. Concretes containing different dosages of fly ash as a replacement for cement (15% and 30% by weight of total cement materials, respectively) were investigated. Concrete without any fly ash added was also employed as the reference specimen. Laboratory tests were conducted to determine the surface layer properties of concrete including chloride transport, apparent water permeability and pore structure. The results demonstrate that incorporation of fly ash, for the early test period, promotes the chloride ingress at the surface layer of concrete but substituting proportions of fly ash may have little impact on it. With the process of chloride immersion, the chloride concentration at the surface layer of concrete with or without fly ash was found to be nearly the same. In addition, it is suggested that the water permeability at the concrete surface area is closely related to the fly ash contents as well as the chloride exposure time. Pore structure was characterized by means of mercury intrusion porosimetry (MIP) test and the scanning electron microscopy (SEM) images. The modification of pore structure of concrete submersed in distilled water is determined by the pozzolanic reaction of fly ash and the calcium leaching effect. The pozzolanic reaction was more dominant at the immersion time of 180 days while the calcium leaching effect became more evident after 270 days.

  14. Air Entrainment and Surface Ripples in a Turbulent Ship Hull Boundary Layer

    Science.gov (United States)

    Masnadi, Naeem; Erinin, Martin; Duncan, James H.

    2017-11-01

    The air entrainment and free-surface fluctuations caused by the interaction of a free surface and the turbulent boundary layer of a vertical surface-piercing plate is studied experimentally. In this experiment, a meter-wide stainless steel belt travels horizontally in a loop around two rollers with vertically oriented axes. This belt device is mounted inside a large water tank with the water level set just below the top edge of the belt. The belt, rollers, and supporting frame are contained within a sheet metal box to keep the device dry except for one 6-meter-long straight test section. The belt is accelerated suddenly from rest until reaching constant speed in order to create a temporally evolving boundary layer analogous to the spatially evolving boundary layer that would exist along a surface-piercing towed flat plate. Surface ripples are measured using a cinematic laser-induced fluorescence technique with the laser sheet oriented parallel or normal to the belt surface. Air entrainment events and bubble motions are recorded from underneath the water surface using a stereo imaging system. Measurements of small bubbles, that tend to stay submerged for a longer time, are planned via a high-speed digital in-line holographic system. The support of the Office of Naval Research is gratefully acknowledged.

  15. Improvement and protection of niobium surface superconductivity by atomic layer deposition and heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Proslier, T.; /IIT, Chicago /Argonne; Zasadzinski, J.; /IIT, Chicago; Moore, J.; Pellin, M.; Elam, J.; /Argonne; Cooley, L.; /Fermilab; Antoine, C.; /Saclay

    2008-11-01

    A method to treat the surface of Nb is described, which potentially can improve the performance of superconducting rf cavities. We present tunneling and x-ray photoemission spectroscopy measurements at the surface of cavity-grade niobium samples coated with a 3 nm alumina overlayer deposited by atomic layer deposition. The coated samples baked in ultrahigh vacuum at low temperature degraded superconducting surface. However, at temperatures above 450 C, the tunneling conductance curves show significant improvements in the superconducting density of states compared with untreated surfaces.

  16. Surface and subsurface layers characterization in artworks using conoscopic laser holography and acoustic microscopy

    Science.gov (United States)

    Marchioro, Giacomo; Apostolidis, Georgios; Karagiannis, Georgios; Galeotti, Monica; Daffara, Claudia

    2017-07-01

    The characterization of the surface morphology and the material layers stratigraphy is a pivotal step in several stages of the conservation process of the artwork. Generally, optimal characterization of the surface cannot be achieved using a single technique but is not always possible to find techniques that can be coupled effectively. Surface maps were retrieved using acoustic microscopy and conoscopic laser holography over a set of reference samples. The surface maps compared for showing possible way to better characterize the surface morphology when their information is combined. The final data give us a more complete surface and subsurface digitalization while the results obtained are discussed highlighting the main pros and cons of the two techniques. Thus besides having insights on the effectiveness and on the performance of the processes, it is also evident that uncertainties associated with the measurement can be overcome and a single more accurate representation of the surface can be derived using both scanning methods.

  17. The gradient structure of the NiTi surface layers subjected to tantalum ion beam alloying

    Science.gov (United States)

    Girsova, S. L.; Poletika, T. M.; Meisner, L. L.; Schmidt, E. Yu

    2017-05-01

    The NiTi shape memory alloy has been modified by ion implantation with Ta to improve the surface and biological properties. The elemental and phase composition and structure of the surface and near-surface layers of NiTi specimens after the Ta ion implantation with the fluency D = 3 × 1017 cm-2 and D = 6 × 1017 cm-2 are examined. The methods of Auger electron spectroscopy (AES), transmission electron microscopy (TEM), and electron dispersion analysis (EDS) are used. It is found that a nonuniform distribution of elements along the depth of the surface layer after the ion implantation of NiTi specimens, regardless of the regime, is accompanied by the formation of a number of sublayer structures.

  18. Making Nonsticky Surfaces of Sticky Materials: Self-Organized Microtexturing of Viscoelastic Elastomeric Layers by Tearing.

    Science.gov (United States)

    Patil, Sandip; Deshpande, Tushar; Chaudhari, Nayantika; Singh, Yogesh R G; Raut, Janhavi; Joshi, Yogesh M; Sharma, Ashutosh

    2018-03-27

    Fabrication of large area, multiscale microtextured surfaces engineered for antiadhesion properties remains a challenge. Compared to an elastic surface, viscoelastic solids show much higher surface stickiness, tack, and adhesion owing to the increased contact area and energy dissipation. Here, we show a simple, low cost, large-area and high throughput method with roll-to-roll compatibility to fabricate multiscale, rough microstructures resistant to adhesion in a viscoelastic layer by controlled tearing of viscous film. Even a high adhesive strength viscoelastic solid layer, such as partially cured PDMS, is made nonsticky simply by its controlled tearing. The torn surface shows a fracture induced, self-organized leaflike micropattern resistant to sticking. The topography and adhesion strength of these structures are readily tuned by changing the tearing speed and the film thickness. The microtexture displays a springlike recovery, low adhesive strength, and easy release properties even under the high applied loads.

  19. Structure of the regular surface layer of Aquaspirillum serpens MW5.

    Science.gov (United States)

    Stewart, M; Murray, R G

    1982-04-01

    The structure of the regular surface layer of Aquaspirillum serpens MW5 has been investigated by electon microscopy supplemented by computer image processing and least-squares analysis. The layer has a ribbed appearance, both on the bacterium and in isolated, negatively stained fragments. However, detailed analysis indicated that the layer was composed of two hexagonal sheets having p6mm symmetry and a = 16 nm. One sheet was staggered by one half repeat along a (1,0) line of the p6nm lattice relative to the second so that, in projection, the pattern of the composite layer was a translational moiré, characterized by a series of ribs spaced 16 nm apart. The ribbed layer had cmm symmetry with a = 32 nm and b = 18.5 nm. Analysis of this pattern indicated that the two p6nm hexagonal sheets were unevenly stained, and this was confirmed by using least-squares methods to simulate the observed pattern by combining two hexagonal patterns. The general structure of the layer was consistent with a role as a selective and protective barrier on the cell surface.

  20. Foam Core Particleboards with Intumescent FRT Veneer: Cone Calorimeter Testing With Varying Adhesives, Surface Layer Thicknesses, and Processing Conditions

    Science.gov (United States)

    Mark A. Dietenberger; Johannes Welling; Ali Shalbafan

    2014-01-01

    Intumescent FRT Veneers adhered to the surface of foam core particleboard to provide adequate fire protection were evaluated by means of cone calorimeter tests (ASTM E1354). The foam core particleboards were prepared with variations in surface layer treatment, adhesives, surface layer thicknesses, and processing conditions. Ignitability, heat release rate profile, peak...

  1. SH surface acoustic wave propagation in a cylindrically layered piezomagnetic/piezoelectric structure.

    Science.gov (United States)

    Du, Jianke; Xian, Kai; Wang, Ji

    2009-01-01

    SH surface acoustic wave (SH-SAW) propagation in a cylindrically layered magneto-electro-elastic structure is investigated analytically, where a piezomagnetic (or piezoelectric) material layer is bonded to a piezoelectric (or piezomagnetic) substrate. By means of transformation, the governing equations of the coupled waves are reduced to Bessel equation and Laplace equation. The boundary conditions imply that the displacements, shear stresses, electric potential, and electric displacements are continuous across the interface between the layer and the substrate together with the traction free at the surface of the layer. The magneto-electrically open and shorted conditions at cylindrical surface are taken to solve the problem. The phase velocity is numerically calculated for different thickness of the layer and wavenumber for piezomagnetic ceramics CoFe(2)O(4) and piezoelectric ceramics BaTiO(3). The effects of magnetic permeability on propagation properties of SH-SAW are discussed in detail. The distributions of displacement, magnetic potential and magneto-electromechanical coupling factor are also figured and discussed.

  2. Phase transformations during machining and properties of surface layers in zirconium dioxide ceramics

    International Nuclear Information System (INIS)

    Grigor'ev, O.N.; Krivoshej, G.S.; Stel'mashenko, N.A.; Trefilov, V.I.; Shevchenko, A.V.

    1991-01-01

    The methods of X-ray allow studying phase composition and inner stresses in the surface layers of partially stabilized zirconium dioxide after mashining. It is shown that under conditions of abrasive treatment transitions from tetragonal into rhomboedric and monoclinic phases initiate. As a result of phase transitions fields of compressible stresses achieving 900 MPa under grinding with ACM abrasive are created on the surface. An essential increase of hardness due to growth of the brittle fauilure resistance and deformation hardening is revealed

  3. A unified account of perceptual layering and surface appearance in terms of gamut relativity.

    Science.gov (United States)

    Vladusich, Tony; McDonnell, Mark D

    2014-01-01

    When we look at the world--or a graphical depiction of the world--we perceive surface materials (e.g. a ceramic black and white checkerboard) independently of variations in illumination (e.g. shading or shadow) and atmospheric media (e.g. clouds or smoke). Such percepts are partly based on the way physical surfaces and media reflect and transmit light and partly on the way the human visual system processes the complex patterns of light reaching the eye. One way to understand how these percepts arise is to assume that the visual system parses patterns of light into layered perceptual representations of surfaces, illumination and atmospheric media, one seen through another. Despite a great deal of previous experimental and modelling work on layered representation, however, a unified computational model of key perceptual demonstrations is still lacking. Here we present the first general computational model of perceptual layering and surface appearance--based on a boarder theoretical framework called gamut relativity--that is consistent with these demonstrations. The model (a) qualitatively explains striking effects of perceptual transparency, figure-ground separation and lightness, (b) quantitatively accounts for the role of stimulus- and task-driven constraints on perceptual matching performance, and (c) unifies two prominent theoretical frameworks for understanding surface appearance. The model thereby provides novel insights into the remarkable capacity of the human visual system to represent and identify surface materials, illumination and atmospheric media, which can be exploited in computer graphics applications.

  4. Electron microscopy of an aluminum layer grown on the vicinal surface of a gallium arsenide substrate

    Energy Technology Data Exchange (ETDEWEB)

    Lovygin, M. V., E-mail: lemi@miee.ru; Borgardt, N. I. [National Research University of Electronic Technology “MIET” (Russian Federation); Kazakov, I. P. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Seibt, M. [Universität Göttingen, IV. Physikalisches Institut (Germany)

    2015-03-15

    A thin Al layer grown by molecular-beam epitaxy on a misoriented GaAs (100) substrate is studied by transmission electron microscopy. Electron diffraction data and bright-field, dark-field, and high-resolution images show that, in the layer, there are Al grains of three types of crystallographic orientation: Al (100), Al (110), and Al (110)R. The specific structural features of the interfaces between the differently oriented grains and substrate are studied by digital processing of the high-resolution images. From quantitative analysis of the dark-field images, the relative content and sizes of the differently oriented grains are determined. It is found that atomic steps at the substrate surface cause an increase in the fraction and sizes of Al (110)R grains and a decrease in the fraction of Al (100) grains, compared to the corresponding fractions and sizes in the layer grown on a singular substrate surface.

  5. Surface Wave Propagation in a Microstretch Thermoelastic Diffusion Material under an Inviscid Liquid Layer

    Directory of Open Access Journals (Sweden)

    Rajneesh Kumar

    2014-01-01

    Full Text Available The present investigation deals with the propagation of Rayleigh type surface waves in an isotropic microstretch thermoelastic diffusion solid half space under a layer of inviscid liquid. The secular equation for surface waves in compact form is derived after developing the mathematical model. The dispersion curves giving the phase velocity and attenuation coefficients with wave number are plotted graphically to depict the effect of an imperfect boundary alongwith the relaxation times in a microstretch thermoelastic diffusion solid half space under a homogeneous inviscid liquid layer for thermally insulated, impermeable boundaries and isothermal, isoconcentrated boundaries, respectively. In addition, normal velocity component is also plotted in the liquid layer. Several cases of interest under different conditions are also deduced and discussed.

  6. Effect of inversion layer at iron pyrite surface on photovoltaic device

    Science.gov (United States)

    Uchiyama, Shunsuke; Ishikawa, Yasuaki; Uraoka, Yukiharu

    2018-03-01

    Iron pyrite has great potential as a thin-film solar cell material because it has high optical absorption, low cost, and is earth-abundant. However, previously reported iron pyrite solar cells showed poor photovoltaic characteristics. Here, we have numerically simulated its photovoltaic characteristics and band structures by utilizing a two-dimensional (2D) device simulator, ATLAS, to evaluate the effects of an inversion layer at the surface and a high density of deep donor defect states in the bulk. We found that previous device structures did not consider the inversion layer at the surface region of iron pyrite, which made it difficult to obtain the conversion efficiency. Therefore, we remodeled the device structure and suggested that removing the inversion layer and reducing the density of deep donor defect states would lead to a high conversion efficiency of iron pyrite solar cells.

  7. Using of standard marine radar for determination of a water surface and an atmosphere near-surface layer parameters

    Science.gov (United States)

    Bogatov, Nikolay A.; Bakhanov, Victor V.; Ermoshkin, Aleksei V.; Kazakov, Vasily I.; Kemarskaya, Olga N.; Titov, Victor I.; Troitskaya, Yulia I.

    2014-10-01

    At present time radar methods of the seas and oceans diagnostics are actively developing. Using of the radar stations based on satellites and planes allows to receive information on a sea surface and a atmosphere near-surface layer with coverage of big water surface areas independently of day time. The developed methods of satellite radio images processing can be applied to marine radar stations. In Institute of Applied Physics RAS works on sea surface diagnostics systems development on the basis of standard marine radar are actively conducted. Despite smaller coverage of the territory in comparison with satellite data, marine radar have possibility to record spatially temporary radar images and to receive information on a surrounding situation quickly. This work deals with results of the researches which were conducted within the international expedition in the Atlantic Ocean in the autumn of 2012 on a route Rotterdam (Netherlands) - Ushuaya (Argentina) - Antarctica — Ushuaya. During this expedition a complex measurements of a sea surface, a atmosphere near-surface layer parameters and subsurface currents in the wide range of hydroweather conditions, including the storm were carried out. The system developed in IAP RAS on the basis of a marine radar ICOM MR-1200RII and the ADC (Analog Digital Converter) block for data recording on the personal computer was used. Display of a non-uniform near-surface current on sea surface radar images in storm conditions is shown. By means of the high-speed anemometer and meteorological station the measurements of the atmosphere parameters were carried out. Comparison of the anemometer data with calculated from radar images is carried out. Dependence of radar cross section from wind speed in the wide range of wind speeds, including storm conditions is investigated. Possibility of marine radar using for surface waves intensity and ice situation estimates also as icebergs detection is shown.

  8. Instrumental research method of qualitative composition of landfill gas in the surface layer of landfills

    Science.gov (United States)

    Gilmanshin, I. R.; Kashapov, N. F.; Gilmanshina, S. I.; Galeeva, A. I.

    2017-09-01

    The article analyzes the practice of waste management in Russia. The system of target indicators of the efficient landfills functioning is formalized. The method of instrumental analysis of concentration and qualitative composition of landfill gas in the surface layer of the Samosyrovo landfill is presented.

  9. Existence of torsional surface waves in an earth's crustal layer lying ...

    Indian Academy of Sciences (India)

    Existence of torsional surface waves in an earth's crustal layer lying over a sandy mantle. Sumit Kumar Vishwakarma1,2,∗ and Shishir Gupta1. 1Department of Applied Mathematics, Indian School of Mines, Dhanbad 826 004, India. 2Department of Mathematics, Birla Institute of Technology and Science–Pilani,. Hyderabad ...

  10. Waves on the surface of a magnetic fluid layer in a traveling magnetic field

    International Nuclear Information System (INIS)

    Zimmermann, K.; Zeidis, I.; Naletova, V.A.; Turkov, V.A.

    2004-01-01

    The plane flow of a layer of incompressible viscous magnetic fluid with constant magnetic permeability under the action of a traveling magnetic field is analyzed. The strength of the magnetic field producing a sinusoidal traveling small-amplitude wave on the surface of a magnetic fluid is found. This flow can be used in designing mobile robots

  11. Photo-oxidation : Major sink of oxygen in the ocean surface layer

    NARCIS (Netherlands)

    Gieskes, W. W. C.; Laane, R. W. P. M.; Ruardij, P.

    2015-01-01

    Evidence is presented that the oxygen demand associated with photochemical processes in the surface layer of oceans and seas worldwide is of the same order of magnitude as the amount of oxygen released by photosynthesis of the world's marine phytoplankton. Both estimates are of necessity quite rough

  12. Photo-oxidation: Major sink of oxygen in the ocean surface layer

    NARCIS (Netherlands)

    Gieskes, W.W.C.; Laane, R.W.P.M.; Ruardij, P.

    2015-01-01

    Evidence is presented that the oxygen demand associated with photochemical processes in the surface layer of oceans and seas worldwide is of the same order of magnitude as the amount of oxygen released by photosynthesis of the world's marine phytoplankton. Both estimates are of necessity quite rough

  13. Theoretical investigation of layered zeolite frameworks: Surface properties of 2D zeolites

    Czech Academy of Sciences Publication Activity Database

    Hermann, Jan; Trachta, Michal; Nachtigall, P.; Bludský, Ota

    2014-01-01

    Roč. 227, May 15 (2014), s. 2-8 ISSN 0920-5861 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388963 Keywords : layered zeolite frameworks * surface properties * 2D zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.893, year: 2014

  14. Relation between the Atmospheric Boundary Layer and Impact Factors under Severe Surface Thermal Conditions

    Directory of Open Access Journals (Sweden)

    Yinhuan Ao

    2017-01-01

    Full Text Available This paper reported a comprehensive analysis on the diurnal variation of the Atmospheric Boundary Layer (ABL in summer of Badain Jaran Desert and discussed deeply the effect of surface thermal to ABL, including the Difference in Surface-Air Temperature (DSAT, net radiation, and sensible heat, based on limited GPS radiosonde and surface observation data during two intense observation periods of experiments. The results showed that (1 affected by topography of the Tibetan Plateau, the climate provided favorable external conditions for the development of Convective Boundary Layer (CBL, (2 deep CBL showed a diurnal variation of three- to five-layer structure in clear days and five-layer ABL structure often occurred about sunset or sunrise, (3 the diurnal variation of DSAT influenced thickness of ABL through changes of turbulent heat flux, (4 integral value of sensible heat which rapidly converted by surface net radiation had a significant influence on the growth of CBL throughout daytime. The cumulative effect of thick RML dominated the role after CBL got through SBL in the development stage, especially in late summer, and (5 the development of CBL was promoted and accelerated by the variation of wind field and distribution of warm advection in high and low altitude.

  15. Surface wave propagation in a double liquid layer over a liquid ...

    Indian Academy of Sciences (India)

    The frequency equation is derived for surface waves in a liquidsaturated porous half-space supporting a double layer, that of inhomogeneous and homogeneous liquids. Asymptotic approximations of Bessel functions are used for long and short wavelength cases. Certain other problems are discussed as special cases.

  16. The use of artificial intelligence methods for visual analysis of properties of surface layers

    Directory of Open Access Journals (Sweden)

    Tomasz Wójcicki

    2014-12-01

    Full Text Available [b]Abstract[/b]. The article presents a selected area of research on the possibility of automatic prediction of material properties based on the analysis of digital images. Original, holistic model of forecasting properties of surface layers based on a multi-step process that includes the selected methods of processing and analysis of images, inference with the use of a priori knowledge bases and multi-valued fuzzy logic, and simulation with the use of finite element methods is presented. Surface layers characteristics and core technologies of their production processes such as mechanical, thermal, thermo-mechanical, thermo-chemical, electrochemical, physical are discussed. Developed methods used in the model for the classification of images of the surface layers are shown. The objectives of the use of selected methods of processing and analysis of digital images, including techniques for improving the quality of images, segmentation, morphological transformation, pattern recognition and simulation of physical phenomena in the structures of materials are described.[b]Keywords[/b]: image analysis, surface layer, artificial intelligence, fuzzy logic

  17. Residual stresses in the surface layer of laser-treated steels

    NARCIS (Netherlands)

    Brussel, B.A. van; Hosson, J.Th.M. De

    1993-01-01

    Although laser treatment of certain metals may enhance the wear performance in general it may result equally well in large residual stresses which affect the wear performance detrimentally. Tensile stresses generated in the surface layer may lead to severe cracking of the material. This paper

  18. On the Temperature and Humidity Dissimilarity in the Marine Surface Layer

    DEFF Research Database (Denmark)

    Larsén, Xiaoli Guo; Kelly, Mark C.; Sempreviva, Anna Maria

    2014-01-01

    The dissimilarity of temperature and humidity transfer in the marine surface layer (MSL) is investigated through the relative transport efficiency and correlation coefficient of these two scalars. We examine their variability and relationship with mean values, as well as spectral characteristics....

  19. On the extension of the wind profile over homogeneous terrain beyond the surface boundary layer

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik; Batchvarova, Ekaterina; Brümmer, B.

    2007-01-01

    Analysis of profiles of meteorological measurements from a 160 m high mast at the National Test Site for wind turbines at H phi vs phi re (Denmark) and at a 250 m high TV tower at Hamburg (Germany) shows that the wind profile based on surface-layer theory and Monin-Obukhov scaling is valid up to ...

  20. The influence of wind speed on surface layer stability and turbulent ...

    Indian Academy of Sciences (India)

    The influence of wind speed on surface layer stability and turbulent fluxes over southern Indian peninsula station. M N Patil∗. , R T Waghmare, T Dharmaraj, G R Chinthalu,. Devendraa Siingh and G S Meena. Indian Institute of Tropical Meteorology, Dr Homi Bhabha Road, Pashan, Pune 411 008, India. ∗. Corresponding ...

  1. Structure fragmentation of a surface layer of commercial purity titanium during ultrasonic impact treatment

    International Nuclear Information System (INIS)

    Kozelskaya, Anna; Kazachenok, Marina; Sinyakova, Elena; Pochivalov, Yurii; Perevalova, Olga; Panin, Alexey; Hairullin, Rustam

    2015-01-01

    The mechanisms of surface layer fragmentation of titanium specimens subjected to ultrasonic impact treatment is investigated by atomic force microscopy, transmission electron microscopy and electron backscatter diffraction. It is shown that the twin boundaries Σ7b and Σ11b are unable to be strong obstacles for propagation of dislocations and other twins

  2. Existence of torsional surface waves in an earth's crustal layer lying ...

    Indian Academy of Sciences (India)

    This paper aims to study the dispersion of torsional surface waves in a crustal layer being sandwiched between a rigid boundary plane and a sandy mantle. In the mantle, rigidity and initial stress vary linearly while density remains constant. Dispersion relation has been deduced in a closed form by means of variable ...

  3. Tensile strength of oxygen plasma-created surface layer of PDMS

    Science.gov (United States)

    Ohishi, Taiki; Noda, Haruka; Matsui, Tsubasa S.; Jile, Huge; Deguchi, Shinji

    2017-01-01

    Polydimethylsiloxane (PDMS) is a commonly used silicone elastomer with broad applications. Particularly for bioengineering use, PDMS is treated with oxygen plasma with which its surface is oxidized to allow positive interaction with water and live cells. In exchange for the acquisition of hydrophilicity, the oxidized PDMS becomes mechanically brittle so that resulting formation of cracks affects the system in various ways. However, tensile strength (TS), which is an inherent capacity of a material to withstand tensile loads before breaking and is thus a key parameter limiting the use of the material, remains unclear regarding oxidized PDMS. Here we determine the TS of oxide layers created on the surface of PDMS based on micro-stretch experiments using a custom-made device. We show that the surface layer displays cracks upon tensile loading of small strains of within 10% to have a TS of ~10-100 kPa, which is approximately two orders of magnitude lower than that of unmodified PDMS. We further show that the TS sharply decreases with oxidation duration to become highly brittle, while the thickness of the resulting oxide layer finally reaches a plateau even with prolonged plasma treatment. Consequently, we suggest that gradual surface modification of PDMS takes place only within a finite region even with prolonged plasma treatment, as distinct from previously held assumptions. These quantitative data provide critical design information for the oxide layer of plasma-hydrophilized PDMS.

  4. Combined effects of surface conditions, boundary layer dynamics and chemistry on diurnal SOA evolution

    Directory of Open Access Journals (Sweden)

    R. H. H. Janssen

    2012-08-01

    Full Text Available We study the combined effects of land surface conditions, atmospheric boundary layer dynamics and chemistry on the diurnal evolution of biogenic secondary organic aerosol in the atmospheric boundary layer, using a model that contains the essentials of all these components. First, we evaluate the model for a case study in Hyytiälä, Finland, and find that it is able to satisfactorily reproduce the observed dynamics and gas-phase chemistry. We show that the exchange of organic aerosol between the free troposphere and the boundary layer (entrainment must be taken into account in order to explain the observed diurnal cycle in organic aerosol (OA concentration. An examination of the budgets of organic aerosol and terpene concentrations show that the former is dominated by entrainment, while the latter is mainly driven by emission and chemical transformation. We systematically investigate the role of the land surface, which governs both the surface energy balance partitioning and terpene emissions, and the large-scale atmospheric process of vertical subsidence. Entrainment is especially important for the dilution of organic aerosol concentrations under conditions of dry soils and low terpene emissions. Subsidence suppresses boundary layer growth while enhancing entrainment. Therefore, it influences the relationship between organic aerosol and terpene concentrations. Our findings indicate that the diurnal evolution of secondary organic aerosols (SOA in the boundary layer is the result of coupled effects of the land surface, dynamics of the atmospheric boundary layer, chemistry, and free troposphere conditions. This has potentially some consequences for the design of both field campaigns and large-scale modeling studies.

  5. Growth of micrometric oxide layers to explore laser decontamination of metallic surfaces

    Directory of Open Access Journals (Sweden)

    Carvalho Luisa

    2017-01-01

    Full Text Available The nuclear industry produces a wide range of radioactive waste in terms of hazard level, contaminants and material. For metallic equipment like steam generators, the radioactivity is mainly located in the oxide surface. In order to study and develop safe techniques for dismantling and for decontamination, it is important to have access to oxide layers with a representative distribution of non-radioactive contaminants. In this paper we propose a method for the creation of oxide layers on stainless steel 304L with europium (Eu as contaminant. This technique consists in spraying an Eu-solution on stainless steel samples. The specimens are firstly treated with a pulsed nanosecond laser after which the steel samples are placed in a 873 K furnace for various durations in order to grow an oxide layer. The oxide structure and in-depth distribution of Eu in the oxide layer were analyzed by scanning electron microscopy coupled to an energy-dispersive X-ray microanalyzer, as well as by glow discharge optical emission or mass spectrometry. The oxide layers were grown to thicknesses in the range of 200 nm–4.5 μm depending on the laser treatment parameters and the heating duration. These contaminated oxides had a ‘duplex structure’ with a mean concentration of the order of 6 × 1016 atoms/cm2 (15 μg/cm2 of europium in the volume of the oxide layer. It appears that europium implementation prevented the oxide growth in the furnace. Nevertheless, the presence of the contamination had no impact on the thickness of the oxide layers obtained by preliminary laser treatment. These oxide layers were used to study the decontamination of metallic surfaces such as stainless steel 304L using a nanosecond pulsed laser.

  6. Analysis of corrosion layers in ancient Roman silver coins with high resolution surface spectroscopic techniques

    International Nuclear Information System (INIS)

    Keturakis, Christopher J.; Notis, Ben; Blenheim, Alex; Miller, Alfred C.; Pafchek, Rob; Notis, Michael R.; Wachs, Israel E.

    2016-01-01

    Highlights: • Five ancient silver alloy coins (225 BCE–244 CE) were analyzed using surface characterization techniques. • Both destructive and non-destructive surface characterization methods were developed. • Alloying with copper, even in small amounts, leads to the formation of an outer Cu 2 O corrosion layer. - Abstract: Determination of the microchemistry of surface corrosion layers on ancient silver alloy coins is important both in terms of understanding the nature of archaeological environmental conditions to which these ancient coins were exposed and also to help in their conservation. In this present study, five ancient silver alloy coins (225 BCE–244 CE) were used as test vehicles to measure their immediate surface microchemistry and evaluate the appropriateness and limitations of High Sensitivity-Low Energy Ion Scattering Spectroscopy (HS-LEIS, 0.3 nm depth analysis), High Resolution-X-ray Photoelectron Spectroscopy (HR-XPS, 1–3 nm depth analysis) and High Resolution-Raman Spectroscopy (HR-Raman, ∼1000 nm depth analysis). Additional information about the deeper corrosion layers, up to ∼300–1000 nm, was provided by dynamic HS-LEIS and HR-Raman spectroscopy. While not archeologically significant, the use of these coins of small commercial value provides data that is more representative of the weaker signals typically obtained from ancient corroded objects, which can be in stark contrast to pristine data often obtained from carefully prepared alloys of known composition. The oldest coins, from 225 to 214 BCE, possessed an outermost surface layer containing Cu 2 O, Na, Al, Pb, and adsorbed hydrocarbons, while the more recent coins, from 98 to 244 CE, contained Cu 2 O, Ag, N, F, Na, Al, S, Cl, and adsorbed hydrocarbons in similar corresponding surface layers. It thus appears that alloying with copper, even in small amounts, leads to the formation of an outer Cu 2 O layer. Depth profiling revealed the presence of K, Na, Cl, and S as key

  7. Specific Features of Chip Making and Work-piece Surface Layer Formation in Machining Thermal Coatings

    Directory of Open Access Journals (Sweden)

    V. M. Yaroslavtsev

    2016-01-01

    Full Text Available A wide range of unique engineering structural and performance properties inherent in metallic composites characterizes wear- and erosion-resistant high-temperature coatings made by thermal spraying methods. This allows their use both in manufacturing processes to enhance the wear strength of products, which have to operate under the cyclic loading, high contact pressures, corrosion and high temperatures and in product renewal.Thermal coatings contribute to the qualitative improvement of the technical level of production and product restoration using the ceramic composite materials. However, the possibility to have a significantly increased product performance, reduce their factory labour hours and materials/output ratio in manufacturing and restoration is largely dependent on the degree of the surface layer quality of products at their finishing stage, which is usually provided by different kinds of machining.When machining the plasma-sprayed thermal coatings, a removing process of the cut-off layer material is determined by its distinctive features such as a layered structure, high internal stresses, low ductility material, high tendency to the surface layer strengthening and rehardening, porosity, high abrasive properties, etc. When coatings are machined these coating properties result in specific characteristics of chip formation and conditions for formation of the billet surface layer.The chip formation of plasma-sprayed coatings was studied at micro-velocities using an experimental tool-setting microscope-based setup, created in BMSTU. The setup allowed simultaneous recording both the individual stages (phases of the chip formation process and the operating force factors.It is found that formation of individual chip elements comes with the multiple micro-cracks that cause chipping-off the small particles of material. The emerging main crack in the cut-off layer of material leads to separation of the largest chip element. Then all the stages

  8. Patterned hydrophobic and hydrophilic surfaces of ultra-smooth nanocrystalline diamond layers

    Energy Technology Data Exchange (ETDEWEB)

    Mertens, M., E-mail: michael.mertens@uni-ulm.de [Institute of Micro and Nanomaterials, Ulm University, 89081 Ulm (Germany); Mohr, M.; Brühne, K.; Fecht, H.J. [Institute of Micro and Nanomaterials, Ulm University, 89081 Ulm (Germany); Łojkowski, M.; Święszkowski, W. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Warsaw (Poland); Łojkowski, W. [Institute of High Pressure Physics, Polish Academy of Sciences, Warsaw (Poland)

    2016-12-30

    Highlights: • Hydrophobic and hydrophilic properties on fluorine-, hydrogen- and oxygen- terminated ultra-nanocrystalline diamond films. • Micropatterned - multi-terminated layers with both hydrophobic and hydrophilic areas on one sample. • Visualization of multi-terminated surfaces by e.g. SEM and LFM. • Roughness and friction investigations on different terminated surfaces. • Smooth and biocompatible surfaces with same roughness regardless of hydrophobicity for microbiological investigations. - Abstract: In this work, we show that ultra nanocrystalline diamond (UNCD) surfaces have been modified to add them hydrophobic and hydrophilic properties. The nanocrystalline diamond films were deposited using the hot filament chemical vapor deposition (HFCVD) technique. This allows growing diamond on different substrates which can be even 3D or structured. Silicon and, for optical applications, transparent quartz glass are the preferred substrates for UNCD layers growth. Fluorine termination leads to strong hydrophobic properties as indicated by a high contact angle for water of more than 100°. Hydrogen termination shows lesser hydrophobic behavior. Hydrophilic characteristics has been realised with oxygen termination. X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) measurements confirm the oxygen and fluorine- termination on the nanocrystalline diamond surface. Further, by micropatterning using photolithography, multi-terminated layers have been created with both hydrophobic and hydrophilic areas. In addition, we have shown that retermination is achieved, and the properties of the surface have been changed from hydrophobic to hydrophilic and vice versa. Micro- roughness and stress in the grown film influences slightly the wetting angle as well. The opportunity to realize local differences in hydrophobicity on nanocrystalline diamond layers, in any size or geometry, offers interesting applications for example in

  9. Structure of adsorption layers and conformation transformations of ethylhydroxyethylcellulose on surfaces of titanium and iron oxides

    Science.gov (United States)

    Bulychev, N. A.; Fomin, V. N.; Malyukova, E. B.; Ur'ev, N. B.

    2011-01-01

    Regularities of the adsorption of ethylhydroxyethylcellulose (EHEC) hydrophilic polymer on a surface of inorganic pigments of TiO2 and Fe2O3 were investigated by infrared spectroscopy. It was found that the adsorption interaction between EHEC and a surface of oxides is accompanied by conformation transformations of the adsorbed molecules of EHEC. The means by which macromolecules bind with active centers on a surface of metal oxides and the influence of the oxides' nature on the EHEC macromolecule conformation transformations determining the structure of the adsorption layer upon adsorption were established.

  10. Surface treatment to form a dispersed Y2O3 layer on Zircaloy-4 tubes

    Science.gov (United States)

    Jung, Yang-Il; Kim, Hyun-Gil; Guim, Hwan-Uk; Lim, Yoon-Soo; Park, Jung-Hwan; Park, Dong-Jun; Yang, Jae-Ho

    2018-01-01

    Zircaloy-4 is a traditional zirconium-based alloy developed for application in nuclear fuel cladding tubes. The surfaces of Zircaloy-4 tubes were treated using a laser beam to increase their mechanical strength. Laser beam scanning of a tube coated with yttrium oxide (Y2O3) resulted in the formation of a dispersed oxide layer in the tube's surface region. Y2O3 particles penetrated the Zircaloy-4 during the laser treatment and were distributed uniformly in the surface region. The thickness of the dispersed oxide layer varied from 50 to 140 μm depending on the laser beam trajectory. The laser treatment also modified the texture of the tube. The preferred basal orientation along the normal to the tube surface disappeared, and a random structure appeared after laser processing. The most obvious result was an increase in the mechanical strength. The tensile strength of Zircaloy-4 increased by 10-20% with the formation of the dispersed oxide layer. The compressive yield stress also increased, by more than 15%. Brittle fracture was observed in the surface-treated samples during tensile and compressive deformation at room temperature; however, the fracture behavior was changed in ductile at elevated temperatures.

  11. An experimental investigation of a compliant surface beneath a turbulent boundary layer

    Science.gov (United States)

    Hess, David Earl

    The interaction between a passive compliant surface and a turbulent boundary layer was studied using a 0.6 m diameter water tunnel. The key idea was the simultaneous determination of surface displacement and turbulence structure. A standard turbulent boundary layer over a flat plate was identified by measuring the first four moments of the streamwise velocity component. Then, two compliant surfaces, consisting of different mixtures of silicone elastomer and silicone oil, were studied by replacing a rigid insert in the flat plate. Varying the amount and viscosity of the oil in the mix allowed one to alter the response of the surface at a variety of Reynolds numbers of interest; in each case, a stable pattern of small amplitude displacements representing the footprints of individual flow structures was obtained. A localized averaging technique (VITA) was used to study any changes in the bursting process that might occur in the presence of a compliant surface. The results indicate that positive pressure pulses which are known to accompany bursting events in the buffer layer produced associated negative displacements in the compliant material beneath.

  12. Theory of the surface dipole layer and of surface tension in liquids of charged particles

    International Nuclear Information System (INIS)

    Senatore, G.; Tosi, M.P.

    1980-01-01

    The problem of the surface density profiles and of the surface tension of a two-component liquid of charged particles in equilibrium with its vapour is examined. The exact equilibrium conditions for the profiles are given in terms of the inverse response functions of the inhomogeneous fluid, and alternative exact expressions for the surface tension are derived. The use of a density gradient expansion reduces the problem to knowledge of properties of a homogeneous charged fluid on a uniform neutralizing background, in which the total particle density and the charge density are independent variables. Additional simplifications are discussed for special cases for which a perturbative treatment of the surface charge density profile can be developed, and in particular for nearly symmetric ionic liquids and for simple liquid metals. (author)

  13. Reconfigurable modified surface layers using plasma capillaries around the neutral inclusion regime

    International Nuclear Information System (INIS)

    Varault, S.; Gabard, B.; Crépin, T.; Bolioli, S.; Sokoloff, J.

    2014-01-01

    We show both theoretically and experimentally reconfigurable properties achieved by plasma inclusions placed in modified surface layers generally used to tailor the transmission and beaming properties of electromagnetic bandgap based waveguiding structures. A proper parametrization of the plasma capillaries allows to reach the neutral inclusion regime, where the inclusions appear to be electromagnetically transparent, letting the surface mode characteristics unaltered. Varying the electron density of the plasma inclusions provoques small perturbations around this peculiar regime, and we observe significant modifications of the transmission/beaming properties. This offers a way to dynamically select the enhanced transmission frequency or to modify the radiation pattern of the structure, depending on whether the modified surface layer is placed at the entrance/exit of the waveguide

  14. Reconfigurable modified surface layers using plasma capillaries around the neutral inclusion regime

    Energy Technology Data Exchange (ETDEWEB)

    Varault, S. [ONERA—The French Aerospace Lab 2, Avenue Edouard Belin, BP4025, 31055 Toulouse Cedex (France); Universite Paul Sabatier—CNRS-Laplace 118, Route de Narbonne, F-31062 Toulouse Cedex 9 (France); Gabard, B. [ONERA—The French Aerospace Lab 2, Avenue Edouard Belin, BP4025, 31055 Toulouse Cedex (France); STAE—4, Rue Emile Monso, BP84234, 31030 Toulouse Cedex 4 (France); Crépin, T.; Bolioli, S. [ONERA—The French Aerospace Lab 2, Avenue Edouard Belin, BP4025, 31055 Toulouse Cedex (France); Sokoloff, J. [Universite Paul Sabatier—CNRS-Laplace 118, Route de Narbonne, F-31062 Toulouse Cedex 9 (France)

    2014-02-28

    We show both theoretically and experimentally reconfigurable properties achieved by plasma inclusions placed in modified surface layers generally used to tailor the transmission and beaming properties of electromagnetic bandgap based waveguiding structures. A proper parametrization of the plasma capillaries allows to reach the neutral inclusion regime, where the inclusions appear to be electromagnetically transparent, letting the surface mode characteristics unaltered. Varying the electron density of the plasma inclusions provoques small perturbations around this peculiar regime, and we observe significant modifications of the transmission/beaming properties. This offers a way to dynamically select the enhanced transmission frequency or to modify the radiation pattern of the structure, depending on whether the modified surface layer is placed at the entrance/exit of the waveguide.

  15. Tile Surface Thermocouple Measurement Challenges from the Orbiter Boundary Layer Transition Flight Experiment

    Science.gov (United States)

    Campbell, Charles H.; Berger, Karen; Anderson, Brian

    2012-01-01

    Hypersonic entry flight testing motivated by efforts seeking to characterize boundary layer transition on the Space Shuttle Orbiters have identified challenges in our ability to acquire high quality quantitative surface temperature measurements versus time. Five missions near the end of the Space Shuttle Program implemented a tile surface protuberance as a boundary layer trip together with tile surface thermocouples to capture temperature measurements during entry. Similar engineering implementations of these measurements on Discovery and Endeavor demonstrated unexpected measurement voltage response during the high heating portion of the entry trajectory. An assessment has been performed to characterize possible causes of the issues experienced during STS-119, STS-128, STS-131, STS-133 and STS-134 as well as similar issues encountered during other orbiter entries.

  16. Surface passivation of efficient nanotextured black silicon solar cells using thermal atomic layer deposition.

    Science.gov (United States)

    Wang, Wei-Cheng; Lin, Che-Wei; Chen, Hsin-Jui; Chang, Che-Wei; Huang, Jhih-Jie; Yang, Ming-Jui; Tjahjono, Budi; Huang, Jian-Jia; Hsu, Wen-Ching; Chen, Miin-Jang

    2013-10-09

    Efficient nanotextured black silicon solar cells passivated by an Al2O3 layer are demonstrated. The broadband antireflection of the nanotextured black silicon solar cells was provided by fabricating vertically aligned silicon nanowire (SiNW) arrays on the n(+) emitter. A highly conformal Al2O3 layer was deposited upon the SiNW arrays by the thermal atomic layer deposition (ALD) based on the multiple pulses scheme. The nanotextured black silicon wafer covered with the Al2O3 layer exhibited a low total reflectance of ∼1.5% in a broad spectrum from 400 to 800 nm. The Al2O3 passivation layer also contributes to the suppressed surface recombination, which was explored in terms of the chemical and field-effect passivation effects. An 8% increment of short-circuit current density and 10.3% enhancement of efficiency were achieved due to the ALD Al2O3 surface passivation and forming gas annealing. A high efficiency up to 18.2% was realized in the ALD Al2O3-passivated nanotextured black silicon solar cells.

  17. Atomic Layer-Deposited TiO2 Coatings on NiTi Surface

    Science.gov (United States)

    Vokoun, D.; Racek, J.; Kadeřávek, L.; Kei, C. C.; Yu, Y. S.; Klimša, L.; Šittner, P.

    2018-02-01

    NiTi shape-memory alloys may release poisonous Ni ions at the alloys' surface. In an attempt to prepare a well-performing surface layer on an NiTi sample, the thermally grown TiO2 layer, which formed during the heat treatment of NiTi, was removed and replaced with a new TiO2 layer prepared using the atomic layer deposition (ALD) method. Using x-ray photoelectron spectroscopy, it was found that the ALD layer prepared at as low a temperature as 100 °C contained Ti in oxidation states + 4 and + 3. As for static corrosion properties of the ALD-coated NiTi samples, they further improved compared to those covered by thermally grown oxide. The corrosion rate of samples with thermally grown oxide was 1.05 × 10-5 mm/year, whereas the corrosion rate of the ALD-coated samples turned out to be about five times lower. However, cracking of the ALD coating occurred at about 1.5% strain during the superelastic mechanical loading in tension taking place via the propagation of a localized martensite band.

  18. Toward an understanding of surface layer formation, growth, and transformation at the glass-fluid interface

    Science.gov (United States)

    Hopf, J.; Eskelsen, J. R.; Chiu, M.; Ievlev, A. V.; Ovchinnikova, O. S.; Leonard, D.; Pierce, E. M.

    2018-05-01

    Silicate glass is a metastable and durable solid that has application to a number of energy and environmental challenges (e.g., microelectronics, fiber optics, and nuclear waste storage). If allowed to react with water over time silicate glass develops an altered layer at the solid-fluid interface. In this study, we used borosilicate glass (LAWB45) as a model material to develop a robust understanding of altered layer formation (i.e., amorphous hydrated surface layer and crystalline reaction products). Experiments were conducted at high surface area-to-volume ratio (∼200,000 m-1) and 90 °C in the pressurized unsaturated flow (PUF) apparatus for 1.5-years to facilitate the formation of thick altered layers and allow for the effluent solution chemistry to be monitored continuously. A variety of microscopy techniques were used to characterize reacted grains and suggest the average altered layer thickness is 13.2 ± 8.3 μm with the hydrated and clay layer representing 74.8% and 25.2% of the total altered layer, respectively. The estimate of hydrated layer thickness is within the experimental error of the value estimated from the B release rate data (∼10 ± 1 μm/yr) over the 1.5-year duration. PeakForce® quantitative nanomechanical mapping results suggest the hydrated layer has a modulus that ranges between ∼20 and 40 GPa, which is in the range of porous silica that contains from ∼20 to ∼50% porosity, yet significantly lower than dense silica (∼70-80 GPa). Scanning transmission electron microscopy (STEM) images confirm the presence of pores and an analysis of a higher resolution image provides a qualitative estimate of ≥22% porosity in the hydrated layer with variations in void volume with increasing distance from the unaltered glass. Chemical composition analyses, based on a combination of time-of-flight secondary-ion mass spectrometry (ToF-SIMS), scanning electron microscopy with X-ray energy dispersive spectroscopy (EDS), and STEM-EDS, clearly show

  19. Frication Property of Mo-Cr-Infiltrated Steel Layer by Plasma Surface Metallurgy

    International Nuclear Information System (INIS)

    Xu Jinyong; Zhicheng, Kang; Liu Yanping; Wang Jianzhong; Gao Yuan; Xu Zhong

    2006-01-01

    Introduced in this article is the technique to acquire a high performance strengthened layer on carbon steel samples, namely, plasma alloying on the surface of Q235 steel and heat treatment technology. With this technique the alloying elements of Mo, Cr, and C can be obtained on the surface of Q235 steel samples. The content of the constituent elements is approximately up to high speed steels (HSS). The surface property required for the HSS after hardening and low tempering is attained. In the test, the alloying elements Mo and Cr were penetrated into the Q235 steel samples by glow discharge sputtering so that the content of the alloyed layer on the surface of the Q235 steel samples was about 20% Mo and 10% Cr. Two kinds of experiments were conducted. One was to carry out ultra-saturated carburization. The alloyed layer's composition was similar to molybdenum HSS with surface carburizing of more than 2.0%. The carbides of the alloyed layer were compact, uniform and disperse without a coarse eutectic ledeburite structure. The another was ion nitriding after the alloying elements of Mo and Cr were penetrated. The first process included hardening with low tempering and hardening with cryogenic treatment for 2 hr and low tempering. The second one was ion nitriding only. It was found that the surface hardness after cryogenic treatment is up to 1600 HV, much higher than that without cryogenic treatment. The abrasion test results indicate that, without the penetrated alloy elements Mo and Cr and without cryogenic treatment and ion nitriding, the friction coefficient is lower by one order of magnitude. The change in relative resistance is similar to the change in the friction coefficient, but without a proportional relationship

  20. Surface morphology evolution of amorphous Fe-Si layers upon thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Sun, C M; Tsang, H K; Wong, S P; Ke, N [Department of Electronic Engineering, Chinese University of Hong Kong, Shatin, NT, Hong Kong (China); Hark, S K [Department of Physics, Chinese University of Hong Kong, Shatin, NT, Hong Kong (China)], E-mail: cmsun@ee.cuhk.edu.hk

    2008-04-21

    Changes in the surface morphology of ion-beam-synthesized amorphous Fe-Si layers after rapid thermal annealing (RTA) and furnace annealing (FA) were investigated using atomic force microscopy and transmission electron microscopy. Completely amorphous Fe-Si layers were formed by Fe implantation at a dosage of 5 x 10{sup 15} cm{sup -2} using a metal vapour vacuum arc ion source under 80 kV extraction voltage and cryogenic temperature. After RTA at 850 deg. C, {beta}-FeSi{sub 2} precipitates in Si are completely aggregated from this amorphous Fe-Si layer and the surface of the implanted layer remains flat. To date, no obvious photoluminescence (PL) spectrum has been reported from RTA treated {beta}-FeSi{sub 2} precipitates. However, after annealing at 850 deg. C for 40 s, high-quality {beta}-FeSi{sub 2} precipitates in Si are obtained which clearly show 1.5 {mu}m PL at 80 K for the first time. Even though additional long-term FA at 850 deg. C can enhance PL intensity to a limited extent, the longer thermal treatment induces the outdiffusion of {beta}-FeSi{sub 2} precipitates and degrades the surface flatness.

  1. Growth of micrometric oxide layers for the study of metallic surfaces decontamination by laser

    Science.gov (United States)

    Carvalho, Luisa; Pacquentin, Wilfried; Tabarant, Michel; Maskrot, Hicham; Semerok, Alexandre

    2017-09-01

    The nuclear industry produces a wide range of radioactive waste in term of level of hazard, contaminants and material. For metallic equipment like steam generators, the radioactivity is mainly located in the oxide surface. In order to study and develop techniques for dismantling and for decontamination in a safe way, it is important to have access to oxide layers with a representative distribution of non-radioactive contaminants. We propose a method of formation of oxide layer on stainless steel 304L with europium (Eu) as contaminant marker. In this method, an Eu-solution is sprayed on the stainless steel samples. The specimen are firstly treated with a pulsed nanosecond laser and secondly the steel samples are exposed to a 600°C furnace for various durations in order to grow an oxide layer. The oxide structure and in-depth distribution of Eu in the oxide layer are analysed by scanning electron microscopy coupled with energy dispersive X-ray microanalyzer, and by glow discharge optical emission or mass spectrometry. The oxide layers were grown to thicknesses in the range of 200 nm to 4.5 μm regarding to the laser treatment parameters and the heating duration. These contaminated oxides have a `duplex structure' with a mean weight percentage of 0.5% of europium in the volume of the oxide layer. It appears that europium implementation prevents the oxide growth by furnace but has no impact on laser heating. These oxide layers are used to study the decontamination of metallic surfaces such as stainless steel 304L using a nanosecond pulsed laser.

  2. Growth of micrometric oxide layers for the study of metallic surfaces decontamination by laser

    Directory of Open Access Journals (Sweden)

    Carvalho Luisa

    2017-01-01

    Full Text Available The nuclear industry produces a wide range of radioactive waste in term of level of hazard, contaminants and material. For metallic equipment like steam generators, the radioactivity is mainly located in the oxide surface. In order to study and develop techniques for dismantling and for decontamination in a safe way, it is important to have access to oxide layers with a representative distribution of non-radioactive contaminants. We propose a method of formation of oxide layer on stainless steel 304L with europium (Eu as contaminant marker. In this method, an Eu-solution is sprayed on the stainless steel samples. The specimen are firstly treated with a pulsed nanosecond laser and secondly the steel samples are exposed to a 600°C furnace for various durations in order to grow an oxide layer. The oxide structure and in-depth distribution of Eu in the oxide layer are analysed by scanning electron microscopy coupled with energy dispersive X-ray microanalyzer, and by glow discharge optical emission or mass spectrometry. The oxide layers were grown to thicknesses in the range of 200 nm to 4.5 μm regarding to the laser treatment parameters and the heating duration. These contaminated oxides have a ‘duplex structure’ with a mean weight percentage of 0.5% of europium in the volume of the oxide layer. It appears that europium implementation prevents the oxide growth by furnace but has no impact on laser heating. These oxide layers are used to study the decontamination of metallic surfaces such as stainless steel 304L using a nanosecond pulsed laser.

  3. Plasma-enhanced deposition of antifouling layers on silicone rubber surfaces

    Science.gov (United States)

    Jiang, Hongquan

    In food processing and medical environments, biofilms serve as potential sources of contamination, and lead to food spoilage, transmission of diseases or infections. Because of its ubiquitous and recalcitrant nature, Listeria monocytogenes biofilm is especially hard to control. Generating antimicrobial surfaces provide a method to control the bacterial attachment. The difficulty of silver deposition on polymeric surfaces has been overcome by using a unique two-step plasma-mediated method. First silicone rubber surfaces were plasma-functionalized to generate aldehyde groups. Then thin silver layers were deposited onto the functionalized surfaces according to Tollen's reaction. X-ray photoelectron spectroscopy (XPS), atomic force spectroscopy (AFM) and scanning electron microscopy (SEM) showed that silver particles were deposited. By exposing the silver coated surfaces to L. monocytogenes, it was demonstrated that they were bactericidal to L. monocytogenes. No viable bacteria were detected after 12 to 18 h on silver-coated silicone rubber surfaces. Another antifouling approach is to generate polyethylene glycol (PEG) thin layer instead of silver on polymer surfaces. Covalent bond of PEG structures of various molecular weights to cold-plasma-functionalized polymer surfaces, such as silicone rubber, opens up a novel way for the generation of PEG brush-like or PEG branch-like anti-fouling layers. In this study, plasma-generated surface free radicals can react efficiently with dichlorosilane right after plasma treatment. With the generation of halo-silane groups, this enables PEG molecules to be grafted onto the modified surfaces. XPS data clearly demonstrated the presence of PEG molecules on plasma-functionalized silicone rubber surfaces. AFM images showed the changed surface morphologies as a result of covalent attachment to the surface of PEG molecules. Biofilm experiment results suggest that the PEG brush-like films have the potential ability to be the next

  4. Growing season boundary layer climate and surface exchanges in a subarctic lichen woodland

    Science.gov (United States)

    Fitzjarrald, David R.; Moore, Kathleen E.

    1994-01-01

    Between June and August 1990, observations were made at two surface micrometeorological towers near Schefferville Quebec (54 deg 52 min N, 66 deg 40.5 min W), one in a fen and one in the subarctic lichen woodland, and at four surface climatological stations. Data from these surface stations were supplemented by regular radiosonde launches. Supporting measurements of radiative components and soil temperatures allowed heat and moisture balances to be obtained at two sites. The overall surface meteorological experiment design and results of micrometeorological observations made on a 30-m tower in the lichen woodland are presented here. Seasonal variation in the heat and water vapor transport characteristics illustrate the marked effect of the late summer climatological shift in air mass type. During the first half of the summer, average valley sidewalls only 100 m high are sufficient to channel winds along the valley in the entire convective boundary layer. Channeling effects at the surface, known for some time at the long-term climate station in Schefferville, are observed both at ridge top and in the valley, possibly the response of the flow to the NW-SE orientation of valleys in the region. Diurnal surface temperature amplitude at ridge top (approximately equal to 10 C) was found to be half that observed in the valley. Relatively large differences in precipitation among these stations and the climatological station at Schefferville airport were observed and attributed to the local topography. Eddy correlation observations of the heat, moisture and momentum transports were obtained from a 30-m tower above a sparse (approximately equal to 616 stems/ha) black spruce lichen woodland. Properties of the turbulent surface boundary layer agree well with previous wind tunnel studies over idealized rough surfaces. Daytime Bowen ratios of 2.5-3 are larger than those reported in previous studies. Surface layer flux data quality was assessed by looking at the surface layer heat

  5. Surface wave propagation in a swelling porous elastic material under a inviscid liquid layer

    Directory of Open Access Journals (Sweden)

    Kuldeep Kumar

    2010-12-01

    Full Text Available The present investigation is to study the surface wave propagationin a swelling porous elastic half space under homogeneous inviscidliquid layer. The frequency equation is derive for both swellingporous (SP and without swelling porous (elastic medium (EL medium. The dispersion curves giving the phase velocity and attenuation coefficient with wave number are plotted graphically to depict the effect of swelling porous half space under a homogeneous inviscid liquid layer. The amplitudes of displacement in both SP and EL medium are obtained and are shown graphically. Some special cases are also deduced from the present investigation.

  6. 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.

  7. Surface and crystal structure of nitridated sapphire substrates and their effect on polar InN layers

    International Nuclear Information System (INIS)

    Skuridina, D.; Dinh, D.V.; Pristovsek, M.; Lacroix, B.; Chauvat, M.-P.; Ruterana, P.; Kneissl, M.; Vogt, P.

    2014-01-01

    Comprehensive analysis of the surface and crystal properties has been performed at clean c-plane sapphire substrates, sapphire layers after nitridation, and subsequently grown InN layers deposited by metal–organic vapor phase epitaxy. The (1 × 1) surface of clean sapphire reconstructs into a (√(31) × √(31))R ± 9° structure after annealing at 1050 °C, which was performed prior to the nitridation process. The formation of crystalline AlN was observed for nitridation above 800 °C. X-ray photoelectron spectroscopy performed on the nitridated layers shows that N-Al chemical bonds dominate this structure, while the number of N-O bonds is negligibly small. Amorphous AlN x O y layers form during nitridation below 800 °C, where N-O bonds dominate. All layers formed by nitridation show defects associated with N bonds. The morphology of the nitridated layers affects the surface and crystal quality of the subsequently grown polar InN layers. N-polar InN layers with a smooth surface and single crystalline structure were grown on the AlN nitridated layers, while In-polar InN layers with a rough surface and a polycrystalline structure were grown on the amorphous nitridated layers.

  8. Reflective practice in ESL teacher development groups from practices to principles

    CERN Document Server

    Farrell, T

    2013-01-01

    Reflective Practise in ESL Teacher Development Groups  discusses the concept of reflective practice in ESL teachers using data from a 3-year collaborative partnership in which three ESL teachers in Canada explored their professional development through reflective practice.

  9. Thin surface layers of SiO2 obtained from tetraethoxysilane (TEOS) in electric discharges stabilized by a dielectric barrier

    International Nuclear Information System (INIS)

    Schmidt-Szalowski, K.; Fabianowski, W.; Rzanek-Boroch, Z.; Gutkowski, R.

    1998-01-01

    The reported research was devoted to the process of thin layer deposition in a discharge at atmospheric pressure stabilized by a dielectric barrier. Thin surface layers composed mainly of silicon dioxide were produced by polycondensation of tetraethoxysilane vapor in mixtures with helium gas with a small amount of oxygen. The influence was studied of the voltage applied and of the time elapsed in the deposition process, on the thickness of the layer, as were the changes of composition of the deposited layers during and after storage. It is shown that good passivating pinhole-free silicon oxide layers can be produced in surface barrier discharges. (J.U.)

  10. Spray Irrigation Effects on Surface-Layer Stability in an Experimental Citrus Orchard during Winter Freezes.

    Science.gov (United States)

    Cooper, Harry J.; Smith, Eric A.; Martsolf, J. David

    1997-02-01

    Observations taken by two surface radiation and energy budget stations deployed in the University of Florida/Institute for Food and Agricultural Service experimental citrus orchard in Gainesville, Florida, have been analyzed to identify the effects of sprayer irrigation on thermal stability and circulation processes within the orchard during three 1992 winter freeze episodes. Lapse rates of temperature observed from a micrometeorological tower near the center of the orchard were also recorded during periods of irrigation for incorporation into the analysis. Comparisons of the near-surface temperature lapse rates observed with the two energy budget stations show consistency between the two sites and with the tower-based lapse rates taken over a vertical layer from 1.5 to 15 m above ground level. A theoretical framework was developed that demonstrates that turbulent-scale processes originating within the canopy, driven by latent heat release associated with condensation and freezing processes from water vapor and liquid water released from sprayer nozzles, can destabilize lapse rates and promote warm air mixing above the orchard canopy. The orchard data were then analyzed in the context of the theory for evidence of local overturning and displacement of surface-layer air, with warmer air from aloft driven by locally buoyant plumes generated by water vapor injected into the orchard during the irrigation periods. It was found that surface-layer lapse rates were lower during irrigation periods than under similar conditions when irrigation was not occurring, indicating a greater degree of vertical mixing of surface-layer air with air from above treetops, as a result of local convective overturning induced by the condensation heating of water vapor released at the nozzles of the sprinklers. This provides an additional explanation to the well-accepted heat of fusion release effect, of how undertree irrigation of a citrus orchard during a freeze period helps protect crops

  11. Connecting meteorology to surface transport in aeolian landscapes: Peering into the boundary layer with Doppler lidar

    Science.gov (United States)

    Gunn, A.; Jerolmack, D. J.; Edmonds, D. A.; Ewing, R. C.; Wanker, M.; David, S. R.

    2017-12-01

    Aolian sand dunes grow to 100s or 1000s of meters in wavelength by sand saltation, which also produces dust plumes that feed cloud formation and may spread around the world. The relations among sediment transport, landscape dynamics and wind are typically observed at the limiting ends of the relevant range: highly resolved and localized ground observations of turbulence and relevant fluxes; or regional and synoptic-scale meteorology and satellite imagery. Between the geostrophic winds aloft and shearing stress on the Earth's surface is the boundary layer, whose stability and structure determines how momentum is transferred and ultimately entrains sediment. Although the literature on atmospheric boundary layer flows is mature, this understanding is rarely applied to aeolian landscape dynamics. Moreover, there are few vertically and time-resolved datasets of atmospheric boundary layer flows in desert sand seas, where buoyancy effects are most pronounced. Here we employ a ground-based upward-looking doppler lidar to examine atmospheric boundary layer flow at the upwind margin of the White Sands (New Mexico) dune field, providing continuous 3D wind velocity data from the surface to 300-m aloft over 70 days of the characteristically windy spring season. Data show highly resolved daily cyles of convective instabilty due to daytime heating and stable stratification due to nightime cooling which act to enhance or depress, respectively, the surface wind stresses for a given free-stream velocity. Our data implicate convective instability in driving strong saltation and dust emission, because enhanced mixing flattens the vertical velocity profile (raising surface wind speed) while upward advection helps to deliver dust to the high atmosphere. We also find evidence for Ekman spiralling, with a magnitude that depends on atmospheric stability. This spiralling gives rise to a deflection in the direction between geostrophic and surface winds, that is significant for the

  12. Metacognition and EFL/ESL Reading.

    Science.gov (United States)

    Carrell, Patricia L.; Wise, Teresa; Gajdusek, Linda

    1998-01-01

    Reviews research streams in metacognition, reading strategies, and training of reading strategies that are converging in the field of English as a foreign or second language (EFL/ESL) and impacting the teaching of English to non-native speakers for academic purposes. A research design for investigating the efficacy of metacognitive strategy…

  13. Mother Goose in the ESL Classroom.

    Science.gov (United States)

    Galeano, Karen

    Mother Goose is well suited to use in the elementary ESL classroom for several reasons. The stories appeal to children's imagination, adhering to the principle that a good story should have surprise value, interesting characters, meaningful conflict, action, and realism. The natural rhythms help develop English intonation, and the stories…

  14. ESL Proficiency and a Word Frequency Count.

    Science.gov (United States)

    Harlech-Jones, Brian

    1983-01-01

    In a study of the vocabulary proficiency of some South African ESL teacher trainees, the General Service List of English Words' validity was evaluated. It was found that mastery of this list would meet most of the vocabulary needs of the test group. Recommendations are made for practical uses of word counts. (MSE)

  15. An ESL Audio-Script Writing Workshop

    Science.gov (United States)

    Miller, Carla

    2012-01-01

    The roles of dialogue, collaborative writing, and authentic communication have been explored as effective strategies in second language writing classrooms. In this article, the stages of an innovative, multi-skill writing method, which embeds students' personal voices into the writing process, are explored. A 10-step ESL Audio Script Writing Model…

  16. Unexpected Poor Comprehenders among Adolescent ESL Students

    Science.gov (United States)

    Li, Miao; Kirby, John R.

    2014-01-01

    This study explored characteristics of reading comprehension difficulties among Chinese students learning English as a second language (ESL). Two hundred forty-six Grade 8 English-immersion students in China were administered a battery of reading-related and reading comprehension tests. Three groups of comprehenders matched on age, nonverbal…

  17. Literature in EFL/ESL Classroom

    Science.gov (United States)

    Khatib, Mohammad; Rezaei, Saeed; Derakhshan, Ali

    2011-01-01

    This paper is a review of literature on how literature can be integrated as a language teaching material in EFL/ESL classes. First, it tracks down the place of literature in language classes from the early Grammar Translation Method (GTM) to Communicative Language Teaching (CLT) era. The paper then discusses the reasons for the demise and…

  18. Hepatitis B ESL education for Asian immigrants.

    Science.gov (United States)

    Taylor, Vicky M; Gregory Hislop, T; Bajdik, Christopher; Teh, Chong; Lam, Wendy; Acorda, Elizabeth; Li, Lin; Yasui, Yutaka

    2011-02-01

    Asian communities in North America include large numbers of immigrants with limited English proficiency. Hepatitis B virus (HBV) infection is endemic in most Asian countries and, therefore, Asian immigrant groups have high rates of chronic HBV infection. We conducted a group-randomized trial to evaluate the effectiveness of a hepatitis B English as a second language (ESL) educational curriculum for Asian immigrants. Eighty ESL classes were randomized to experimental (hepatitis B education) or control (physical activity education) status. Students who reported they had not received a HBV test (at baseline) completed a follow-up survey 6 months after randomization. The follow-up survey assessed recent HBV testing and HBV-related knowledge. Provider reports were used to verify self-reported HBV tests. The study group included 218 students who reported they had not been tested for HBV. Follow-up surveys were completed by 180 (83%) of these students. Provider records verified HBV testing for 6% of the experimental group students and 0% of the control group students (P = 0.02). Experimental group students were significantly (P ESL curriculum had a meaningful impact on HBV-related knowledge and a limited impact on HBV testing levels. Future research should evaluate the effectiveness of ESL curricula for other immigrant groups and other health topics, as well as other intervention approaches to increasing levels of HBV testing in Asian immigrant communities.

  19. The Role of Transitions in ESL Instruction

    Science.gov (United States)

    Steinman, Linda

    2013-01-01

    Transitions in ESL contexts generally refer to those linking words placed between sentences and between paragraphs. Transitions in writing (and in speaking) are helpful; they facilitate coherence and cohesion when used correctly. Understanding them when reading allows us to join the writer in seeing why and how idea B follows idea A. In this…

  20. Experimental studies of the stress state of the surface layer of detailat treatment with submerged jets

    Directory of Open Access Journals (Sweden)

    Олександр Олександрович Анділахай

    2015-03-01

    Full Text Available In the instrument and electrical industry was the use of the method of abrasive machining submerged jet, which is the most promising method for abrasive blasting of small parts of low stiffness. This method eliminates the main drawback сhip plants - abrasion channel nozzles or injection nozzles, but the state of the surface layer of machined parts are poorly understood and to make maximum use of the potential to provide the required quality parameters. The study of the state of the surfaces of parts resulting from abrasive blasting traditional methods, dedicated work, which define quality indicators: microhardness depth residual stress, as well as their nature (compressive, tensile. However, known from the literature values correspond to the conditions of surface treatment of parts in a fixed state with an abrasive material through the feed nozzle, and therefore the dynamics of the interaction of a single abrasive grain and significantly different parts. The process in question, and different modes of processing characteristics of the abrasive grains. In the paper, a series of experimental studies designed to assess the state of machined surfaces of parts as a result of abrasion submerged jets. It is established that during the treatment the non-oriented disorderly traces overlay the abrasive grains on the treated surface, thereby forming a tight skin layer thickness of 4 - 5 micrometers. Processed surface gets cold working, as evidenced by the study of microhardness before and after abrasive machining in a free state submerged jets

  1. Durability of simulated waste glass: effects of pressure and formation of surface layers

    International Nuclear Information System (INIS)

    Wicks, G.G.; Mosley, W.C.; Whitkop, P.G.; Saturday, K.A.

    1981-01-01

    The leaching behavior of simulated Savannah River Plant (SRP) waste glass was studied at elevated pressures and anticipated storage temperatures. An integrated approach, which combined leachate solution analyses with both bulk and surface studies, was used to study the corrosion process. Compositions of leachates were evaluated by colorimetry and atomic absorption. Used in the bulk and surface analyses were optical microscopy, scanning electron microscopy, x-ray energy spectroscopy, wide-angle x-ray, diffraction, electron microprobe analysis, infrared reflectance spectroscopy, electron spectroscopy for chemical analysis, and Auger electron spectroscopy. Results from this study show that there is no significant adverse effect of pressure, up to 1500 psi and 90 0 C, on the chemical durability of simulated SPR waste glass leached for one month in deionized water. In addition, the leached glass surface layer was characterized by an adsorbed film rich in minor constituents from the glass. This film remained on the glass surface even after leaching in relatively alkaline solutions at elevated pressures at 90 0 C for one month. The sample surface area to volume of leachant ratios (SA/V) was 10:1 cm -1 and 1:10 cm -1 . The corrosion mechanisms and surface and subsurface layers produced will be discussed along with the potential importance of these results to repository storage

  2. The Interaction of a Turbulent Ship-Hull Boundary Layer and a Free Surface

    Science.gov (United States)

    Masnadi, N.; Washuta, N.; Wang, A.; Duncan, J. H.

    2013-11-01

    The free-surface deformation pattern caused by subsurface turbulent velocity fluctuations in the boundary layer at the mid-length of a naval ship is studied with a novel laboratory scale experimental technique. In this technique, the boundary layer is created in a large tank (13.4 m long, 1.3 m tall, and 2.4 m wide) with a surface-piercing meter-wide stainless steel belt that travels in a horizontal loop around two vertically oriented rollers whose axes are separated by 7.5 m. The device is enclosed in a dry box except for one of the two lengths between the rollers where a straight 6-meter-long section is exposed to the water and represents one side of the ship hull. The belt operates at full-scale ship speeds (up to 15 m/s) in order to match the Reynolds, Froude, and Weber numbers to those of naval ships, thus faithfully modeling the interaction of the turbulence with the free surface at laboratory scale. The water surface profile history midway between the rollers is recorded cinematically in a vertical plane normal to the belt using a Laser Induced Fluorescence (LIF) technique. This surface profile data is used to study the near-wall and far-field frequency content and propagation behavior of the surface ripples. The support of the Office of Naval Research is gratefully acknowledged.

  3. Hydrogen-bonding layer-by-layer-assembled biodegradable polymeric micelles as drug delivery vehicles from surfaces.

    Science.gov (United States)

    Kim, Byeong-Su; Park, Sang Wook; Hammond, Paula T

    2008-02-01

    We present the integration of amphiphilic block copolymer micelles as nanometer-sized vehicles for hydrophobic drugs within layer-by-layer (LbL) films using alternating hydrogen bond interactions as the driving force for assembly for the first time, thus enabling the incorporation of drugs and pH-sensitive release. The film was constructed based on the hydrogen bonding between poly(acrylic acid) (PAA) as an H-bond donor and biodegradable poly(ethylene oxide)-block-poly(epsilon-caprolactone) (PEO-b-PCL) micelles as the H-bond acceptor when assembled under acidic conditions. By taking advantage of the weak interactions of the hydrogen-bonded film on hydrophobic surfaces, it is possible to generate flexible free-standing films of these materials. A free-standing micelle LbL film of (PEO-b-PCL/PAA)60 with a thickness of 3.1 microm was isolated, allowing further characterization of the bulk film properties, including morphology and phase transitions, using transmission electron microscopy and differential scanning calorimetry. Because of the sensitive nature of the hydrogen bonding employed to build the multilayers, the film can be rapidly deconstructed to release micelles upon exposure to physiological conditions. However, we could also successfully control the rate of film deconstruction by cross-linking carboxylic acid groups in PAA through thermally induced anhydride linkages, which retard the drug release to the surrounding medium to enable sustained release over multiple days. To demonstrate efficacy in delivering active therapeutics, in vitro Kirby-Bauer assays against Staphylococcus aureus were used to illustrate that the drug-loaded micelle LbL film can release significant amounts of an active antibacterial drug, triclosan, to inhibit the growth of bacteria. Because the micellar encapsulation of hydrophobic therapeutics does not require specific chemical interactions, we believe this noncovalent approach provides a new route to integrating active small

  4. Self-cleaning and surface chemical reactions during hafnium dioxide atomic layer deposition on indium arsenide.

    Science.gov (United States)

    Timm, Rainer; Head, Ashley R; Yngman, Sofie; Knutsson, Johan V; Hjort, Martin; McKibbin, Sarah R; Troian, Andrea; Persson, Olof; Urpelainen, Samuli; Knudsen, Jan; Schnadt, Joachim; Mikkelsen, Anders

    2018-04-12

    Atomic layer deposition (ALD) enables the ultrathin high-quality oxide layers that are central to all modern metal-oxide-semiconductor circuits. Crucial to achieving superior device performance are the chemical reactions during the first deposition cycle, which could ultimately result in atomic-scale perfection of the semiconductor-oxide interface. Here, we directly observe the chemical reactions at the surface during the first cycle of hafnium dioxide deposition on indium arsenide under realistic synthesis conditions using photoelectron spectroscopy. We find that the widely used ligand exchange model of the ALD process for the removal of native oxide on the semiconductor and the simultaneous formation of the first hafnium dioxide layer must be significantly revised. Our study provides substantial evidence that the efficiency of the self-cleaning process and the quality of the resulting semiconductor-oxide interface can be controlled by the molecular adsorption process of the ALD precursors, rather than the subsequent oxide formation.

  5. A Case Study of Offshore Advection of Boundary Layer Rolls over a Stably Stratified Sea Surface

    DEFF Research Database (Denmark)

    Svensson, Nina; Sahlée, Erik; Bergström, Hans

    2017-01-01

    originate from boundary layer rolls generated over the convective air above Swedish mainland, also supported by visual satellite images showing the typical signature cloud streets. The simulations indicate that the rolls are advected and maintained at least 30–80 km off the coast, in agreement...... with the streaks observed by the SAR images. During evening when the convective conditions over land diminish, the streaky structures over the sea are still seen in the horizontal wind field; however, the vertical component is close to zero. Thus advected feature from a land surface can affect the wind field...... considerably for long times and over large areas in coastal regions. Although boundary layer rolls are a well-studied feature, no previous study has presented results concerning their persistence during situations with advection to a strongly stratified boundary layer. Such conditions are commonly encountered...

  6. Method for the manufacture of a superconductive Nb3Sn layer on a niobium surface for high frequency applications

    International Nuclear Information System (INIS)

    Martens, H.

    1978-01-01

    A manufacturing method for depositing an Nb 3 Sn layer on a niobium surface for high frequency applications comprising developing a tin vapor atmosphere which also contains a highly volatile tin compound in the gaseous state, and holding the portions of the surface which are to be provided with the Nb 3 Sn layer at a temperature of between 900 0 and 1500 0 C for a predetermined period of time to form the Nb 3 Sn layer permitting niobium surfaces of any shape to be provided with Nb 3 Sn layers of high uniformity and quality

  7. Bacterial surface layer proteins as a novel capillary coating material for capillary electrophoretic separations

    Energy Technology Data Exchange (ETDEWEB)

    Moreno-Gordaliza, Estefanía, E-mail: emorenog@ucm.es [Division of Analytical Biosciences, Leiden Academic Centre for Drug Research, Universiteit Leiden, Einsteinweg 55, 2300, RA, Leiden (Netherlands); Department of Analytical Chemistry, Faculty of Chemistry, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040, Madrid (Spain); Stigter, Edwin C.A. [Division of Analytical Biosciences, Leiden Academic Centre for Drug Research, Universiteit Leiden, Einsteinweg 55, 2300, RA, Leiden (Netherlands); Department of Molecular Cancer Research, Universitair Medisch Centrum Utrecht, Wilhelmina Kinder Ziekenhuis, Lundlaan 6, 3584, EA Utrecht (Netherlands); Lindenburg, Petrus W.; Hankemeier, Thomas [Division of Analytical Biosciences, Leiden Academic Centre for Drug Research, Universiteit Leiden, Einsteinweg 55, 2300, RA, Leiden (Netherlands)

    2016-06-07

    A novel concept for stable coating in capillary electrophoresis, based on recrystallization of surface layer proteins on hydrophobized fused silica capillaries, was demonstrated. Surface layer protein A (SlpA) from Lactobacillus acidophilus bacteria was extracted, purified and used for coating pre-silanized glass substrates presenting different surface wettabilities (either hydrophobic or hydrophilic). Contact angle determination on SlpA-coated hydrophobic silica slides showed that the surfaces turned to hydrophilic after coating (53 ± 5°), due to a protein monolayer formation by protein-surface hydrophobic interactions. Visualization by atomic force microscopy demonstrated the presence of a SlpA layer on methylated silica slides displaying a surface roughness of 0.44 ± 0.02 nm. Additionally, a protein layer was visualized by fluorescence microscopy in methylated silica capillaries coated with SlpA and fluorescein isothiocyanate-labeled. The SlpA-coating showed an outstanding stability, even after treatment with 20 mM NaOH (pH 12.3). The electroosmotic flow in coated capillaries showed a partial suppression at pH 7.50 (3.8 ± 0.5 10{sup −9} m{sup 2} V{sup −1} s{sup −1}) when compared with unmodified fused silica (5.9 ± 0.1 10{sup −8} m{sup 2} V{sup −1} s{sup −1}). To demonstrate the potential of this novel coating, the SlpA-coated capillaries were applied for the first time for electrophoretic separation, and proved to be very suitable for the isotachophoretic separation of lipoproteins in human serum. The separations showed a high degree of repeatability (absolute migration times with 1.1–1.8% coefficient-of-variation (CV) within a day) and 2–3% CV inter-capillary reproducibility. The capillaries were stable for more than 100 runs at pH 9.40, and showed to be an exceptional alternative for challenging electrophoretic separations at long-term use. - Highlights: • New coating using recrystallized surface-layer proteins on

  8. Electrical properties of surface and interface layers of the N- and In-polar undoped and Mg-doped InN layers grown by PA MBE

    Science.gov (United States)

    Komissarova, T. A.; Kampert, E.; Law, J.; Jmerik, V. N.; Paturi, P.; Wang, X.; Yoshikawa, A.; Ivanov, S. V.

    2018-01-01

    Electrical properties of N-polar undoped and Mg-doped InN layers and In-polar undoped InN layers grown by plasma-assisted molecular beam epitaxy (PA MBE) were studied. Transport parameters of the surface and interface layers were determined from the measurements of the Hall coefficient and resistivity as well as the Shubnikov-de Haas oscillations at magnetic fields up to 60 T. Contributions of the 2D surface, 3D near-interface, and 2D interface layers to the total conductivity of the InN films were defined and discussed to be dependent on InN surface polarity, Mg doping, and PA MBE growth conditions.

  9. Surface Behavior of Rhodamin and Tartrazine on Silica-Cellulose Sol-Gel Surfaces by Thin Layer Elution

    Directory of Open Access Journals (Sweden)

    Surjani Wonorahardjo

    2016-05-01

    Full Text Available Physical and chemical interactions are the principles for different types of separation systems as the equillibrium dynamics on surface plays a key-role. Surface modification is a way for selective separation at interfaces. Moreover, synthesis of gel silica by a sol-gel method is preferred due to the homogeneity and surface feature easily controlled. Cellulose can be added in situ to modified the silica features during the process. Further application for to study interaction of rhodamin and tartrazine in its surface and their solubilities in mobile phase explains the possibility for their separation. This paper devoted to evaluate the surface behavior in term of adsorption and desorption of tartrazine and rhodamin on silica-cellulose thin layer in different mobile phase. Some carrier liquids applied such as methanol, acetone, n-hexane and chloroform. The result proves tartrazine and rhodamin is separated and have different behavior in different mobile phase. The retardation factors (Rf of the mixtures suggest complexity behavior on silica-cellulose surface.

  10. How Do Chinese ESL Learners Recognize English Words during a Reading Test? A Comparison with Romance-Language-Speaking ESL Learners

    Science.gov (United States)

    Li, Hongli; Suen, Hoi K.

    2015-01-01

    This study examines how Chinese ESL learners recognize English words while responding to a multiple-choice reading test as compared to Romance-language-speaking ESL learners. Four adult Chinese ESL learners and three adult Romance-language-speaking ESL learners participated in a think-aloud study with the Michigan English Language Assessment…

  11. A peculiar mode of formation of the surface lining layer in the lungs of Salamandra salamandra.

    Science.gov (United States)

    Goniakowska-Witalińska, L

    1980-01-01

    The pneumocytes of the larva of Salamandra salamandra contain numerous lamellar bodies and their precursors: electron-dense bodies at various stages of development. Both lamellar bodies and electron-dense bodies occur inside the fluid-filled lung. The former are spherical or bell-shaped and possess concentrically arranged smooth membranes, 8 nm thicks; the latter have paracrystalline cores composed of alternatively oriented clear and dark striations (3 . 6--3 . 9 nm and 2 . 6--3 . 6 nm, respectively). On all sides such cores separate membranes, which assume a concentric orientation. No tubular myelin was observed in any phase of the transformation of lamellar bodies and electron-dense bodies into the surface lining layer. Fixation of the lungs of adult individuals with tannic acid-containing fixative visualized the surface lining layer, but not tubular myelin.

  12. Lead-free, bronze-based surface layers for wear resistance in axial piston hydraulic pumps

    Energy Technology Data Exchange (ETDEWEB)

    Vetterick, Gregory Alan [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    Concerns regarding the safety of lead have provided sufficient motivation to develop substitute materials for the surface layer on a thrust bearing type component known as a valve plate in axial piston hydraulic pumps that consists of 10% tin, 10% lead, and remainder cooper (in wt. %). A recently developed replacement material, a Cu-10Sn-3Bi (wt.%) P/M bronze, was found to be unsuitable as valve plate surface layer, requiring the development of a new alloy. A comparison of the Cu-1-Sn-10Pb and Cu-10Sn-3Bi powder metal valve plates showed that the differences in wear behavior between the two alloys arose due to the soft phase bismuth in the alloy that is known to cause both solid and liquid metal embrittlement of copper alloys.

  13. Study on Mud Pumping Mechanism of Subgrade Surface Layer in Slab Ballastless Track Zone

    Directory of Open Access Journals (Sweden)

    Xiaopei CAI

    2015-03-01

    Full Text Available Mud pumping has a significant impact on dynamic behavior of high-speed railway. An elaborate study focused on the structure characteristics of CRTS I (China Railway Track System slab ballastless track was made to explain the mechanism of mud pumping from the aspects of displacement between the base plate and subgrade, gap growing, disfunction of drainage system and dynamic load of the train. Finite element software ABAQUS was applied to simulate the dynamic responses between the base plate and the subgrade surface layer in different conditions of gap length and gap size. It has been found that the dynamic force between the base plate and the surface layer of subgrade is up to 4,576.29 kN. Suggestions have been given to the related department such as slip-casting, white-out, sealing plug to solve the problem.

  14. Study of surface layer on 08Kh15N5D2T steel

    International Nuclear Information System (INIS)

    Tyurin, A.G.; Povolotskij, V.D.; Zhivotovskij, Eh.A.; Berg, B.N.

    1986-01-01

    08Kh15N5D2T steel phase composition is investigated. Its surface layer was determined by X-ray diffraction analysis method. It is shown, that a subscale appears to be the reason for corrosion of products, made of EhP410 steel. Under the existing smelling technology the carbon content in it is ≥ 0.05%. Therefore to avoid the metal surface depletion with chromium, one must provide for titanium relation to carbon of not less than 4.5 and carry out the rolled product thermal treatment in a protective atmosphere; otherwise, the technology must include not only the removal of scale from steel but the metal subscale layer as well

  15. Wear Characteristic of Stellite 6 Alloy Hardfacing Layer by Plasma Arc Surfacing Processes

    Directory of Open Access Journals (Sweden)

    Zhiyuan Zhu

    2017-01-01

    Full Text Available The microstructure and wear resistance of Stellite 6 alloy hardfacing layer at two different temperatures (room temperature and 300°C were investigated by plasma arc surfacing processes on Q235 Steel. Tribological test was conducted to characterize the wear property. The microstructure of Stellite 6 alloy coating mainly consists of α-Co and (Cr, Fe7C3 phases. The friction coefficient of Stellite 6 alloys fluctuates slightly under different loads at 300°C. The oxide layer is formed on the coating surface and serves as a special lubricant during the wear test. Abrasive wear is the dominant mechanism at room temperature, and microploughing and plasticity are the key wear mechanisms at 300°C.

  16. Natural convection - radiation interaction in boundary layer flow over horizontal surfaces

    International Nuclear Information System (INIS)

    Ali, M.M.; Chen, T.S.; Armaly, B.F.

    1982-01-01

    A numerical model is developed for natural convection-radiation interaction in the boundary layer over a semi-infinite horizontal flat plate with one hot and one cold surface. The fluid is assumed to be gray, to emit, absorb, be nonscattering, and constant with a density variation in the vertical direction, which induces a buoyancy force. Two-dimensional, boundary-layer equations are defined, and the radiative heat flux is simplified using a Rosseland approximation. Conservation equations are transformed into a system of nonlinear ordinary differential equations which can be solved simultaneously with a Runge-Kutta integration scheme, along with the Newton-Raphson shooting technique. The thermal radiation is found to enhance the wall shear stress and the surface heat transfer rate on both the hot and cold sides

  17. First-order dissolution rate law and the role of surface layers in glass performance assessment

    Science.gov (United States)

    Grambow, B.; Müller, R.

    2001-09-01

    The first-order dissolution rate law is used for nuclear waste glass performance predictions since 1984. A first discussion of the role of saturation effects was initiated at the MRS conference that year. In paper (1) it was stated that "For glass dissolution A* (the reaction affinity) cannot become zero since saturation only involves the reacting surface while soluble elements still might be extracted from the glass" [B. Grambow, J. Mater. Res. Soc. Symp. Proc. 44 (1985) 15]. Saturation of silica at the surface and condensation of surface silanol groups was considered as being responsible for the slow down of reaction rates by as much as a factor of 1000. Precipitation of Si containing secondary phases such as quartz was invoked as a mechanism for keeping final dissolution affinities higher than zero. Another (2) paper [A.B. Barkatt, P.B. Macedo, B.C. Gibson, C.J. Montrose, J. Mater. Res. Soc. Symp. Proc. 44 (1985) 3] stated that "… under repository conditions the extent of glass dissolution will be moderate due to saturation with respect to certain major elements (in particular, Si, Al and Ca). Consequently, the concentration levels of the more soluble glass constituents in the aqueous medium are expected to fall appreciable below their solubility limit." The formation of dense surface layers was considered responsible for explaining the saturation effect. The mathematical model assumed stop of reaction in closed systems, once solubility limits were achieved. For more than 15 years the question of the correctness of one or the other concept has seldom been posed and has not yet been resolved. The need of repository performance assessment for validated rate laws demands a solution, particularly since the consequences of the two concepts and research requirements for the long-term glass behavior are quite different. In concept (1) the stability of the `equilibrium surface region' is not relevant because, by definition, this region is stable chemically and after a

  18. Structure and nano-mechanical characteristics of surface oxide layers on a metallic glass.

    Science.gov (United States)

    Caron, A; Qin, C L; Gu, L; González, S; Shluger, A; Fecht, H-J; Louzguine-Luzgin, D V; Inoue, A

    2011-03-04

    Owing to their low elastic moduli, high specific strength and excellent processing characteristics in the undercooled liquid state, metallic glasses are promising materials for applications in micromechanical systems. With miniaturization of metallic mechanical components down to the micrometer scale, the importance of a native oxide layer on a glass surface is increasing. In this work we use TEM and XPS to characterize the structure and properties of the native oxide layer grown on Ni(62)Nb(38) metallic glass and their evolution after annealing in air. The thickness of the oxide layer almost doubled after annealing. In both cases the oxide layer is amorphous and consists predominantly of Nb oxide. We investigate the friction behavior at low loads and in ambient conditions (i.e. at T = 295 K and 60% air humidity) of both as-cast and annealed samples by friction force microscopy. After annealing the friction coefficient is found to have significantly increased. We attribute this effect to the increase of the mechanical stability of the oxide layer upon annealing.

  19. Turbulent Characterization of atmospheric surface layer over non-homogeneous terrain

    International Nuclear Information System (INIS)

    Artinano Rodriguez de Torres, B.

    1989-01-01

    About 15000 wind and temperature profiles from a 100 m tower located in CEDER (Soria, Spain) have been analyzed. Using profiles in close neutral conditions, two main parameters of surface layer were obtained. Results show a great dependence of these parameters (Z 0 roughness length and u friction velocity) on flow conditions and terrain (tinctures. Difficulty finding neutral conditions in this type of terrain (gently rolling and scattered bush) and in this latitude , is also remarkable. (Author) 91 refs

  20. Phosphorus Speciation of Forest-soil Organic Surface Layers using P K-edge XANES Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    J Prietzel; J Thieme; D Paterson

    2011-12-31

    The phosphorus (P) speciation of organic surface layers from two adjacent German forest soils with different degree of water-logging (Stagnosol, Rheic Histosol) was analyzed by P K-edge XANES and subsequent Linear Combination Fitting. In both soils, {approx}70% of the P was inorganic phosphate and {approx}30% organic phosphate; reduced P forms such as phosphonate were absent. The increased degree of water-logging in the Histosol compared to the Stagnosol did not affect P speciation.

  1. Gases Emission From Surface Layers of Sand Moulds and Cores Stored Under the Humid Air Conditions

    Directory of Open Access Journals (Sweden)

    Kaźnica N.

    2017-12-01

    Full Text Available A large number of defects of castings made in sand moulds is caused by gases. There are several sources of gases: gases emitted from moulds, cores or protective coatings during pouring and casting solidification; water in moulding sands; moisture adsorbed from surroundings due to atmospheric conditions changes. In investigations of gas volumetric emissions of moulding sands amounts of gases emitted from moulding sand were determined - up to now - in dependence of the applied binders, sand grains, protective coatings or alloys used for moulds pouring. The results of investigating gas volumetric emissions of thin-walled sand cores poured with liquid metal are presented in the hereby paper. They correspond to the surface layer in the mould work part, which is decisive for the surface quality of the obtained castings. In addition, cores were stored under conditions of a high air humidity, where due to large differences in humidity, the moisture - from surroundings - was adsorbed into the surface layer of the sand mould. Due to that, it was possible to asses the influence of the adsorbed moisture on the gas volumetric emission from moulds and cores surface layers by means of the new method of investigating the gas emission kinetics from thin moulding sand layers heated by liquid metal. The results of investigations of kinetics of the gas emission from moulding sands with furan and alkyd resins as well as with hydrated sodium silicate (water glass are presented. Kinetics of gases emissions from these kinds of moulding sands poured with Al-Si alloy were compared.

  2. Effect of magnetic field on nonlinear interactions of electromagnetic and surface waves in a plasma layer

    International Nuclear Information System (INIS)

    Khalil, Sh.M.; El-Sherif, N.; El-Siragy, N.M.; Tanta Univ.; El-Naggar, I.A.; Alexandria Univ.

    1985-01-01

    Investigation is made for nonlinear interaction between incident radiation and a surface wave in a magnetized plasma layer. Both interacting waves are of P polarization. The generated currents and fields at combination frequencies are obtained analytically. Unlike the S-polarized interacting waves, the magnetic field affects the fundamental waves and leads to an amplification of generated waves when their frequencies approach the cyclotron frequency. (author)

  3. CONCENTRATION DEPENDENCE OF STERN LAYER CAPACITANCES AND SURFACE EQUILIBRIUM CONSTANTS IN SILICA-BASED NANOFLUIDIC CHANNELS

    DEFF Research Database (Denmark)

    Andersen, Mathias Bækbo; Frey, J.; Bruus, Henrik

    2010-01-01

    Fundamental understanding of the unique physics at the solid-liquid interface in nanofluidic channels is essential for the advancement of basic scientific knowledge and the development of novel applications for pharmaceuticals, environmental health and safety, energy harvesting and biometrics [1......]. The current models used to describe surface phenomena in nanofluidics can differ by orders of magnitude from experimentally measured values [2]. To mitigate the discrepancies, we hypothesize that the Stern-layer capacitance Cs and the surface equilibrium constants pKa, vary with the composition of the solid...

  4. Microhardness changes gradient of the duplex stainless steel (DSS surface layer after dry turning

    Directory of Open Access Journals (Sweden)

    G. Krolczyk

    2014-10-01

    Full Text Available The article presents the gradient of microhardness changes as a function of the distance from the material surface after turning with a wedge provided with a coating with a ceramic intermediate layer. The investigation comprised the influence of cutting speed on surface integrity microhardness in dry machining. The tested material was duplex stainless steel (DSS with two-phase, ferritic-austenitic structure. The tests have been performed under production conditions during machining of parts for electric motors and deep-well pumps.

  5. Study the formation of porous surface layer for a new biomedical titanium alloy

    Science.gov (United States)

    Talib Mohammed, Mohsin; Diwan, Abass Ali; Ali, Osamah Ihsan

    2018-03-01

    In the present work, chemical treatment using hydrogen peroxide (H2O2) oxidation and subsequent thermal treatment was applied to create a uniform porous layer over the surface of a new metastable β-Ti alloy. The results revealed that this oxidation treatment can create a stable ultrafine porous film over the oxidized surface. This promoted the electrochemical characteristics of H2O2-treated Ti-Zr-Nb (TZN) alloy system, presenting nobler corrosion behavior in simulated body fluid (SBF) comparing with untreated sample.

  6. Surface plasmon enhanced organic solar cells with a MoO3 buffer layer.

    Science.gov (United States)

    Su, Zisheng; Wang, Lidan; Li, Yantao; Zhang, Guang; Zhao, Haifeng; Yang, Haigui; Ma, Yuejia; Chu, Bei; Li, Wenlian

    2013-12-26

    High-efficiency surface plasmon enhanced 1,1-bis-(4-bis(4-methyl-phenyl)-amino-phenyl)-cyclohexane:C70 small molecular bulk heterojunction organic solar cells with a MoO3 anode buffer layer have been demonstrated. The optimized device based on thermal evaporated Ag nanoparticles (NPs) shows a power conversion efficiency of 5.42%, which is 17% higher than the reference device. The improvement is attributed to both the enhanced conductivity and increased absorption due to the near-field enhancement of the localized surface plasmon resonance of Ag NPs.

  7. Hybrid Doping of Few-Layer Graphene via a Combination of Intercalation and Surface Doping

    KAUST Repository

    Mansour, Ahmed

    2017-05-23

    Surface molecular doping of graphene has been shown to modify its work function and increase its conductivity. However, the associated shifts in work function and increases in carrier concentration are highly coupled and limited by the surface coverage of dopant molecules on graphene. Here we show that few-layer graphene (FLG) can be doped using a hybrid approach, effectively combining surface doping by larger (metal-)organic molecules, while smaller molecules, such as Br2 and FeCl3, intercalate into the bulk. Intercalation tunes the carrier concentration more effectively, whereas surface doping of intercalated FLG can be used to tune its work function without reducing the carrier mobility. This multi-modal doping approach yields a very high carrier density and tunable work function for FLG, demonstrating a new versatile platform for fabricating graphene-based contacts for electronic, optoelectronic and photovoltaic applications.

  8. Surface defect states in MBE-grown CdTe layers

    Energy Technology Data Exchange (ETDEWEB)

    Olender, Karolina; Wosinski, Tadeusz; Fronc, Krzysztof; Tkaczyk, Zbigniew; Chusnutdinow, Sergij; Karczewski, Grzegorz [Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw (Poland)

    2014-02-21

    Semiconductor surface plays an important role in the technology of semiconductor devices. In the present work we report results of our deep-level transient spectroscopy (DLTS) investigations of surface defect states in nitrogen doped p-type CdTe layers grown by the molecular-beam epitaxy technique. We observed a deep-level trap associated with surface states, with the activation energy for hole emission of 0.33 eV. DLTS peak position in the spectra for this trap, and its ionization energy, strongly depend on the electric field. Our measurements allow to determine a mechanism responsible for the enhancement of hole emission rate from the traps as the phonon-assisted tunnel effect. Density of surface defect states significantly decreased as a result of passivation in ammonium sulfide. Capacitance-voltage measurements confirmed the results obtained by the DLTS technique.

  9. Study on microstructure and properties of Mg-alloy surface alloying layer fabricated by EPC

    Directory of Open Access Journals (Sweden)

    Chen Dongfeng

    2010-02-01

    Full Text Available AZ91D surface alloying was investigated through evaporative pattern casting (EPC technology. Aluminum powder (0.074 to 0.104 mm was used as the alloying element in the experiment. An alloying coating with excellent properties was fabricated, which mainly consisted of adhesive, co-solvent, suspending agent and other ingredients according to desired proportion. Mg-alloy melt was poured under certain temperature and the degree of negative pressure. The microstructure of the surface layer was examined by means of scanning electron microscopy. It has been found that a large volume fraction of network new phases were formed on the Mg-alloy surface, the thickness of the alloying surface layer increased with the alloying coating increasing from 0.3 mm to 0.5 mm, and the microstructure became compact. Energy dispersive X-ray (EDX analysis was used to determine the chemical composition of the new phases. It showed that the new phases mainly consist of β-Mg17Al12, in addition to a small quantity of inter-metallic compounds and oxides. A micro-hardness test and a corrosion experiment to simulate the effect of sea water were performed. The result indicated that the highest micro-hardness of the surface reaches three times that of the matrix. The corrosion rate of alloying samples declines to about a fifth of that of the as-cast AZ91D specimen.

  10. Effect of a surface oxide-dispersion-strengthened layer on mechanical strength of zircaloy-4 tubes

    Directory of Open Access Journals (Sweden)

    Yang-Il Jung

    2018-03-01

    Full Text Available An oxide-dispersion-strengthened (ODS layer was formed on Zircaloy-4 tubes by a laser beam scanning process to increase mechanical strength. Laser beam was used to scan the yttrium oxide (Y2O3–coated Zircaloy-4 tube to induce the penetration of Y2O3 particles into Zircaloy-4. Laser surface treatment resulted in the formation of an ODS layer as well as microstructural phase transformation at the surface of the tube. The mechanical strength of Zircaloy-4 increased with the formation of the ODS layer. The ring-tensile strength of Zircaloy-4 increased from 790 to 870 MPa at room temperature, from 500 to 575 MPa at 380°C, and from 385 to 470 MPa at 500°C. Strengthening became more effective as the test temperature increased. It was noted that brittle fracture occurred at room temperature, which was not observed at elevated temperatures. Resistance to dynamic high-temperature bursting improved. The burst temperature increased from 760 to 830°C at a heating rate of 5°C/s and internal pressure of 8.3 MPa. The burst opening was also smaller than those in fresh Zircaloy-4 tubes. This method is expected to enhance the safety of Zr fuel cladding tubes owing to the improvement of their mechanical properties. Keywords: Laser Surface Treatment, Microstructure, Oxide Dispersion Strengthened Alloy, Tensile Strength, Zirconium Alloy

  11. Changes of surface layer of nitrogen-implanted AISI316L stainless steel

    International Nuclear Information System (INIS)

    Budzynski, P.; Polanski, K.; Kobzev, A.P.

    2007-01-01

    The effects of nitrogen ion implantation into AISI316L stainless steel on friction, wear, and microhardness have been investigated at an energy level of 125 keV at a fluence of 1·10 17 - 1·10 18 N/cm 2 . The composition of the surface layer was investigated by RBS, XRD (GXRD), SEM and EDX. The friction coefficient and abrasive wear rate of the stainless steel were measured in the atmospheres of air, oxygen, argon, and in vacuum. As follows from the investigations, there is an increase in resistance to frictional wear in the studied samples after implantation; however, these changes are of different characters in various atmospheres. The largest decrease in wear was observed during tests in the air, and the largest reduction in the value of the friction coefficient for all implanted samples was obtained during tests in the argon atmosphere. Tribological tests revealed larger contents of nitrogen, carbon, and oxygen in the products of surface layer wear than in the surface layer itself of the sample directly after implantation

  12. Experimental investigation of moving surfaces for boundary layer and circulation control of airfoils and wings

    Science.gov (United States)

    Vets, Robert

    An experimental study was conducted to assess the application of a moving surface to affect boundary layers and circulation around airfoils for the purpose of altering and enhancing aerodynamic performance of finite wings at moderate Reynolds numbers. The moving surface was established by a wide, lightweight, nylon belt that enveloped a wing's symmetric airfoil profile articulated via a friction drive cylinder such that the direction of the upper surface was in the direction of the free stream. A water tunnel visualization study accompanied wind tunnel testing at the University of Washington, Kirsten Wind Tunnel of finite wings. An experimental study was conducted to assess the application of a moving surface to affect boundary layers and circulation around airfoils for the purpose of altering and enhancing aerodynamic performance of finite wings at moderate Reynolds numbers. The moving surface was established by a wide, lightweight, nylon belt that enveloped a wing's symmetric airfoil profile articulated via a friction drive cylinder such that the direction of the upper surface was in the direction of the free stream. A water tunnel visualization study accompanied wind tunnel testing at the University of Washington, Kirsten Wind Tunnel of finite wings. The defining non-dimensional parameter for the system is the ratio of the surface velocity to the free stream velocity, us/Uo. Results show a general increase in lift with increasing us/Uo. The endurance parameter served as an additional metric for the system's performance. Examining the results of the endurance parameter shows general increase in endurance and lift with the moving surface activated. Peak performance in terms of increased endurance along with increased lift occurs at or slightly above us/Uo = 1. Water tunnel visualization showed a marked difference in the downwash for velocity ratios greater than 1, supporting the measured data. Reynolds numbers for this investigation were 1.9E5 and 4.3E5, relevant

  13. Development of gold induced surface plasmon enhanced CIGS absorption layer on polyimide substrate

    Science.gov (United States)

    Park, Seong-Un; Sharma, Rahul; Sim, Jae-Kwan; Baek, Byung Joon; Ahn, Haeng-Kwun; Kim, Jin Soo; Lee, Cheul-Ro

    2013-09-01

    Localized surface plasmon resonance (LSPR) with metal nanoparticles is the promising phenomenon to increase light absorption by trapping light in thin film solar cells. In this study we demonstrate a successful LSPR effect with gold (Au) nanoparticles onto the Cu(In,Ga)Se2 (CIGS) absorption layer. First, the CIGS absorber layers is fabricated onto the Mo coated polyimide (PI) substrate by using two stage process as DC sputtering of CIG thin film followed by the selenization at 400 °C. Finally, the Au nanoparticles are deposited onto the CIGS layer with increasing particles size from 4-15 nm by using sputter coater for 10-120 s. The X-ray diffraction (XRD) patterns confirm the formation of CIGS/Au nanocomposite structure with prominent peak shift of CIGS reflections and increasing intensity for Au phase. The CIGS/Au nanocomposite morphologies with Au particle size distribution uniformity and surface coverage is examined under ultra-high resolution field effect scanning electron microscope (UHR-FESEM). A peak at 176 cm-1 in Raman spectra, associated with the “A1” mode of lattice vibration for the attributed to the pure chalcopyrite structure. The secondary ion mass spectroscopy (SIMS) showed ∼200 nm depth converge of Au nanoparticles into the CIGS absorption layer. The optical properties as transmittance, reflectance and absorbance of CIGS/Au layers were found to expand in the infrared region and the LSPR effect is the most prominent for Au particles (5-7 nm) deposited for 60 s. The absorption coefficient and band gap measurement also confirms that the LSPR effect for 5-7 nm Au particles with band gap improvement from 1.31 to 1.52 eV for CIGS/Au layer as the defect density decreases due to the deposition of Au nanoparticles onto the CIGS layer. Such LSPR effect in CIGS/Au nanocomposite absorption layer will be a key parameter to further improve performance of the solar cell.

  14. Development of gold induced surface plasmon enhanced CIGS absorption layer on polyimide substrate

    International Nuclear Information System (INIS)

    Park, Seong-Un; Sharma, Rahul; Sim, Jae-Kwan; Baek, Byung Joon; Ahn, Haeng-Kwun; Kim, Jin Soo; Lee, Cheul-Ro

    2013-01-01

    Localized surface plasmon resonance (LSPR) with metal nanoparticles is the promising phenomenon to increase light absorption by trapping light in thin film solar cells. In this study we demonstrate a successful LSPR effect with gold (Au) nanoparticles onto the Cu(In,Ga)Se 2 (CIGS) absorption layer. First, the CIGS absorber layers is fabricated onto the Mo coated polyimide (PI) substrate by using two stage process as DC sputtering of CIG thin film followed by the selenization at 400 °C. Finally, the Au nanoparticles are deposited onto the CIGS layer with increasing particles size from 4–15 nm by using sputter coater for 10–120 s. The X-ray diffraction (XRD) patterns confirm the formation of CIGS/Au nanocomposite structure with prominent peak shift of CIGS reflections and increasing intensity for Au phase. The CIGS/Au nanocomposite morphologies with Au particle size distribution uniformity and surface coverage is examined under ultra-high resolution field effect scanning electron microscope (UHR-FESEM). A peak at 176 cm −1 in Raman spectra, associated with the “A1” mode of lattice vibration for the attributed to the pure chalcopyrite structure. The secondary ion mass spectroscopy (SIMS) showed ∼200 nm depth converge of Au nanoparticles into the CIGS absorption layer. The optical properties as transmittance, reflectance and absorbance of CIGS/Au layers were found to expand in the infrared region and the LSPR effect is the most prominent for Au particles (5–7 nm) deposited for 60 s. The absorption coefficient and band gap measurement also confirms that the LSPR effect for 5–7 nm Au particles with band gap improvement from 1.31 to 1.52 eV for CIGS/Au layer as the defect density decreases due to the deposition of Au nanoparticles onto the CIGS layer. Such LSPR effect in CIGS/Au nanocomposite absorption layer will be a key parameter to further improve performance of the solar cell.

  15. Effect of the Parameters of Gas-Powder Laser Surfacing on the Structural Characteristics of Reconditioned Surface Layer of Corrosion-Resistant Steels

    Science.gov (United States)

    Krylova, S. E.; Oplesnin, S. P.; Manakov, N. A.; Yasakov, A. S.; Strizhov, A. O.

    2018-01-01

    Results of the developed commercial process for reconditioning the surface of corrosion-resistant steels by the method of laser surfacing are presented. A comparative analysis of the microstructures of the deposited wear-resistant layer, of the zone of fusion with the matrix material and of the diffusion zone after different variants of surfacing is performed. The hardness of the deposited layer is measured and a nondestructive inspection of the latter for the presence of flaws is performed.

  16. Study on conditional probability of surface rupture: effect of fault dip and width of seismogenic layer

    Science.gov (United States)

    Inoue, N.

    2017-12-01

    The conditional probability of surface ruptures is affected by various factors, such as shallow material properties, process of earthquakes, ground motions and so on. Toda (2013) pointed out difference of the conditional probability of strike and reverse fault by considering the fault dip and width of seismogenic layer. This study evaluated conditional probability of surface rupture based on following procedures. Fault geometry was determined from the randomly generated magnitude based on The Headquarters for Earthquake Research Promotion (2017) method. If the defined fault plane was not saturated in the assumed width of the seismogenic layer, the fault plane depth was randomly provided within the seismogenic layer. The logistic analysis was performed to two data sets: surface displacement calculated by dislocation methods (Wang et al., 2003) from the defined source fault, the depth of top of the defined source fault. The estimated conditional probability from surface displacement indicated higher probability of reverse faults than that of strike faults, and this result coincides to previous similar studies (i.e. Kagawa et al., 2004; Kataoka and Kusakabe, 2005). On the contrary, the probability estimated from the depth of the source fault indicated higher probability of thrust faults than that of strike and reverse faults, and this trend is similar to the conditional probability of PFDHA results (Youngs et al., 2003; Moss and Ross, 2011). The probability of combined simulated results of thrust and reverse also shows low probability. The worldwide compiled reverse fault data include low fault dip angle earthquake. On the other hand, in the case of Japanese reverse fault, there is possibility that the conditional probability of reverse faults with less low dip angle earthquake shows low probability and indicates similar probability of strike fault (i.e. Takao et al., 2013). In the future, numerical simulation by considering failure condition of surface by the source

  17. Drag reduction using wrinkled surfaces in high Reynolds number laminar boundary layer flows

    Science.gov (United States)

    Raayai-Ardakani, Shabnam; McKinley, Gareth H.

    2017-09-01

    Inspired by the design of the ribbed structure of shark skin, passive drag reduction methods using stream-wise riblet surfaces have previously been developed and tested over a wide range of flow conditions. Such textures aligned in the flow direction have been shown to be able to reduce skin friction drag by 4%-8%. Here, we explore the effects of periodic sinusoidal riblet surfaces aligned in the flow direction (also known as a "wrinkled" texture) on the evolution of a laminar boundary layer flow. Using numerical analysis with the open source Computational Fluid Dynamics solver OpenFOAM, boundary layer flow over sinusoidal wrinkled plates with a range of wavelength to plate length ratios ( λ / L ), aspect ratios ( 2 A / λ ), and inlet velocities are examined. It is shown that in the laminar boundary layer regime, the riblets are able to retard the viscous flow inside the grooves creating a cushion of stagnant fluid that the high-speed fluid above can partially slide over, thus reducing the shear stress inside the grooves and the total integrated viscous drag force on the plate. Additionally, we explore how the boundary layer thickness, local average shear stress distribution, and total drag force on the wrinkled plate vary with the aspect ratio of the riblets as well as the length of the plate. We show that riblets with an aspect ratio of close to unity lead to the highest reduction in the total drag, and that because of the interplay between the local stress distribution on the plate and stream-wise evolution of the boundary layer the plate has to exceed a critical length to give a net decrease in the total drag force.

  18. Structure and properties of titanium surface layers after electron beam alloying with powder mixtures containing carbon

    International Nuclear Information System (INIS)

    Lenivtseva, O.G.; Bataev, I.A.; Golkovskii, M.G.; Bataev, A.A.; Samoilenko, V.V.; Plotnikova, N.V.

    2015-01-01

    Highlights: • Wear resistant coatings up to 2 mm thick were clad on titanium by an electron beam in air. • The microhardness of the alloys was increased from 2 to 8 GPa due to the formation of TiC particles. • Alloying of titanium increased the abrasive wear resistance of the alloy by a factor of 9.3. - Abstract: The structure and tribological properties of commercially pure titanium (cp-Ti) samples after non-vacuum electron beam surface alloying with carbon were studied. Two types of powders were used to introduce carbon in surface layer of cp-Ti: titanium carbide (TiC) and mixture of pure titanium and graphite (“Ti + C”). Single layer and multilayer coatings were studied. Application of electron beam for alloying provided cladding rate of 4.5 m 2 /h. The thickness of the clad coatings was 1.6–2.0 mm. The main phases received after “Ti + C” powder cladding were α-titanium, TiC, and retained graphite. In the samples obtained by cladding of TiC, graphite was not observed. A factor determining the microhardness and tribological properties of the cladded layer was the volume fraction of TiC. Maximum coating microhardness of 8 GPa was obtained by cladding of single layer of TiC powder or two layers of the “Ti + C” mixture. Two types of tests were carried out to evaluate the wear resistance of the samples. In friction tests against loose abrasive particles, the wear rate of the best samples was 9.3 times lower than that of cp-Ti. In wear tests using fixed abrasive particles, the relative wear resistance of the best samples was 2.3 times higher than that of cp-Ti.

  19. Assembly, Structure, and Functionality of Metal-Organic Networks and Organic Semiconductor Layers at Surfaces

    Science.gov (United States)

    Tempas, Christopher D.

    Self-assembled nanostructures at surfaces show promise for the development of next generation technologies including organic electronic devices and heterogeneous catalysis. In many cases, the functionality of these nanostructures is not well understood. This thesis presents strategies for the structural design of new on-surface metal-organic networks and probes their chemical reactivity. It is shown that creating uniform metal sites greatly increases selectivity when compared to ligand-free metal islands. When O2 reacts with single-site vanadium centers, in redox-active self-assembled coordination networks on the Au(100) surface, it forms one product. When O2 reacts with vanadium metal islands on the same surface, multiple products are formed. Other metal-organic networks described in this thesis include a mixed valence network containing Pt0 and PtII and a network where two Fe centers reside in close proximity. This structure is stable to temperatures >450 °C. These new on-surface assemblies may offer the ability to perform reactions of increasing complexity as future heterogeneous catalysts. The functionalization of organic semiconductor molecules is also shown. When a few molecular layers are grown on the surface, it is seen that the addition of functional groups changes both the film's structure and charge transport properties. This is due to changes in both first layer packing structure and the pi-electron distribution in the functionalized molecules compared to the original molecule. The systems described in this thesis were studied using high-resolution scanning tunneling microscopy, non-contact atomic force microscopy, and X-ray photoelectron spectroscopy. Overall, this work provides strategies for the creation of new, well-defined on-surface nanostructures and adds additional chemical insight into their properties.

  20. Ensemble Data Assimilation to Characterize Surface-Layer Errors In Numerical Weather Prediction Models

    Science.gov (United States)

    Hacker, Joshua; Angevine, Wayne

    2013-04-01

    Experiments with the single-column implementation of the Weather Research and Forecasting mesoscale model provide a basis for deducing land-atmosphere coupling errors in the model. Coupling occurs both through heat and moisture fluxes through the land-atmosphere interface and roughness sub-layer, and turbulent heat, moisture, and momentum fluxes through the atmospheric surface layer. This work primarily addresses the turbulent fluxes, which are parameterized following Monin-Obukhov similarity theory applied to the atmospheric surface layer. By combining ensemble data assimilation and parameter estimation, the model error can be characterized. Ensemble data assimilation of 2-m temperature and water vapor mixing ratio, and 10-m wind components, forces the model to follow observations during a month-long simulation for a column over the well-instrumented ARM Central Facility near Lamont, OK. One-hour errors in predicted observations are systematically small but non-zero, and the systematic errors measure bias as a function of local time of day. Analysis increments for state elements nearby (15-m AGL) can be too small or have the wrong sign, indicating systematically biased covariances and model error. Experiments using the ensemble filter to objectively estimate a parameter controlling the thermal land-atmosphere coupling show that the parameter adapts to offset the model errors, but that the errors cannot be eliminated. Results suggest either structural error or further parametric error that may be difficult to estimate. Experiments omitting atypical observations such as soil and flux measurements lead to qualitatively similar deductions, showing potential for assimilating common in-situ observations as an inexpensive framework for deducing and isolating model errors. We finish by presenting recent results from a deeper examination of the second-moment ensemble statistics, which demonstrate the effect of assimilation on the coupling through the stability function in

  1. Scaling properties of velocity and temperature spectra above the surface friction layer in a convective atmospheric boundary layer

    Directory of Open Access Journals (Sweden)

    K. G. McNaughton

    2007-06-01

    Full Text Available We report velocity and temperature spectra measured at nine levels from 1.42 meters up to 25.7 m over a smooth playa in Western Utah. Data are from highly convective conditions when the magnitude of the Obukhov length (our proxy for the depth of the surface friction layer was less than 2 m. Our results are somewhat similar to the results reported from the Minnesota experiment of Kaimal et al. (1976, but show significant differences in detail. Our velocity spectra show no evidence of buoyant production of kinetic energy at at the scale of the thermal structures. We interpret our velocity spectra to be the result of outer eddies interacting with the ground, not "local free convection".

    We observe that velocity spectra represent the spectral distribution of the kinetic energy of the turbulence, so we use energy scales based on total turbulence energy in the convective boundary layer (CBL to collapse our spectra. For the horizontal velocity spectra this scale is (zi εo2/3, where zi is inversion height and εo is the dissipation rate in the bulk CBL. This scale functionally replaces the Deardorff convective velocity scale. Vertical motions are blocked by the ground, so the outer eddies most effective in creating vertical motions come from the inertial subrange of the outer turbulence. We deduce that the appropriate scale for the peak region of the vertical velocity spectra is (z εo2/3 where z is height above ground. Deviations from perfect spectral collapse under these scalings at large and small wavenumbers are explained in terms of the energy transport and the eddy structures of the flow.

    We find that the peaks of the temperature spectra collapse when wavenumbers are scaled using (z1/2 zi1/2. That is, the lengths of the thermal structures depend on both the lengths of the

  2. Surface plasmon resonance image sensor module of spin-coated silver film with polymer layer.

    Science.gov (United States)

    Son, Jung-Han; Lee, Dong Hun; Cho, Yong-Jin; Lee, Myung-Hyun

    2013-11-01

    Prism modules of 20 nm-, 40 nm-, and 60 nm-thick spin-coated silver films both without and with an upper 100 nm-thick spin-coated polymer layer were fabricated for surface plasmon resonance (SPR) image sensor applications. The prism modules were applied to an SPR image sensor system. The coefficients of determination (R2s) for the 20 nm-, 40 nm- and 60 nm-thick silver films without the polymer layer were 0.9231, 0.9901, and 0.9889, respectively, and with the polymer layer 0.9228, 0.9951, and 0.9880, respectively when standard ethanol solutions with 0.1% intervals in the range of 20.0% to 20.5% were applied. The upper polymer layer has no effect on the R2. The prism modules of the 40-nm-thick spin-coated silver films had the highest R2 value of approximately 0.99. The durability of the 40 nm-thick spin-coated silver film with the 100 nm-thick polymer layer is much better than that without the upper low-loss polymer layer. The developed SPR image sensor module of the 40 nm-thick spin-coated silver film with the upper 100 nm-thick low-loss polymer film is expected to be a very cost-effective and robust solution because the films are formed at low temperatures in a short period of time without requiring a vacuum system and are very durable.

  3. Evolution of the lower planetary boundary layer over strongly contrasting surfaces

    International Nuclear Information System (INIS)

    Coulter, R.L.; Gao, W.; Martin, T.J.; Shannon, J.D.; Doran, J.C.; Hubbe, J.M.; Shaw, W.M.

    1992-01-01

    In a multilaboratory field study held near Boardman in northeastern Oregon in June 1991, various properties of the surface and lower atmospheric boundary layer over heavily irrigated cropland and adjacent desert steppe were investigated in the initial campaign of the Atmospheric Radiation Measurement (ARM) program. The locale was selected because its disparate characteristics over various spatial scales stress the ability of general circulation models (GCMS) to describe lower boundary conditions, particularly across the discontinuity between desert (in which turbulent flux of heat must be primarily as sensible heat) and large irrigated tracts (in which turbulent flux of latent heat should be the larger term). This campaign of ARM seeks to increase knowledge in three critical areas: (1) determination of the relationships between surface heat fluxes measured over multiple scales and the controlling surface parameters within each scale, (2) integration of local and nearly local heat flux estimates to produce estimates appropriate for GCM grid cells of 100-200 km horizontal dimension, and (3) characterization of the growth and development of the atmospheric boundary layer near transitions between surfaces with strongly contrasting moisture availabilities

  4. Carbohydrate composition of rat intestine surface mucus layer after ceftriaxone treatment

    Directory of Open Access Journals (Sweden)

    Yu. V. Holota

    2016-12-01

    Full Text Available The epidemiological studies have shown that antibiotic treatment increases the susceptibility to inflammatory bowel disease development. The disturbance of mucus layer integrity might be one of the possible mechanisms. The aim of the present study was to investigate the effect of antibiotic ceftriaxone treatment on glycoproteins level and its carbohydrate composition in surface mucus layer of rat intestine. The study was done on male Wistar rats (140-160 g. Ceftriaxone (300 mg/kg, i.m. was administered once a day for 14 days. The surface mucus from terminal ileum and colon were collected on the 15th, 29th and 72nd days of the experiment. Total level of mucus glycoproteins, hexoses, hexosamines, fucose and sialic acids were measured. Ceftriaxone administration did not affect the levels of glycoproteins in rat ileum. In the colon, the levels of glycoprotein were 1.3-fold decreased (Р < 0.05 on the 72nd day of the experiment. These changes were accompanied by the 1.2-fold decrease of hexoses (Р < 0.05 and 3.1-fold (Р < 0.05 decrease of fucose level and 1.5-fold (Р < 0.05 increase of the levels of sialic acids in the surface mucus of the rat colon. Thus, ceftriaxone administration induces the long-term changes in the levels of glycoproteins and carbohydrates composition in the rat colon surface mucus. This could potentially explain the susceptibility to inflammatory bowel disea­ses development.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  6. Time-resolved PIV of a turbulent boundary layer over a spanwise-oscillating surface

    Science.gov (United States)

    Gouder, Kevin; Morrison, Jonathan

    2012-11-01

    This work reports measurements of a turbulent boundary layer at Reθ ~ 2500, over a resonant spanwise-oscillating surface driven by a linear electromagnetic motor. Time-resolved PIV measurements of velocity are presented and supplemented by hot-wire measurements of velocity and direct drag measurements of friction drag using a drag balance. A maximum of 16% surface friction reduction, as calculated by the diminution of the wall-normal streamwise velocity gradient was obtained. The PIV laser beam was parallel to the plane of the oscillating surface at a height of y+ ~ 15, hence, top-down views of the near-wall turbulence activity and the effect of the surface oscillation on its evolution were obtained. It has been shown that the imposition of a spanwise Stokes-like layer at a non-dimensional period of T+ =Tuτ2 / ν ~ 100 at peak-peak oscillation amplitudes equal to or larger than the mean streak spacing enabled the direct manipulation of the quasi-streamwise near-wall structures and caused fundamental changes in their evolution leading to reductions, for example, in the near-wall values of the mean-square of the streamwise fluctuating velocity component. This work was supported by Qinetiq, Airbus and EPSRC.

  7. Surface-Layer (S-Layer) Proteins Sap and EA1 Govern the Binding of the S-Layer-Associated Protein BslO at the Cell Septa of Bacillus anthracis

    Science.gov (United States)

    Kern, Valerie J.; Kern, Justin W.; Theriot, Julie A.; Schneewind, Olaf

    2012-01-01

    The Gram-positive pathogen Bacillus anthracis contains 24 genes whose products harbor the structurally conserved surface-layer (S-layer) homology (SLH) domain. Proteins endowed with the SLH domain associate with the secondary cell wall polysaccharide (SCWP) following secretion. Two such proteins, Sap and EA1, have the unique ability to self-assemble into a paracrystalline layer on the surface of bacilli and form S layers. Other SLH domain proteins can also be found within the S layer and have been designated Bacillus S-layer-associated protein (BSLs). While both S-layer proteins and BSLs bind the same SCWP, their deposition on the cell surface is not random. For example, BslO is targeted to septal peptidoglycan zones, where it catalyzes the separation of daughter cells. Here we show that an insertional lesion in the sap structural gene results in elongated chains of bacilli, as observed with a bslO mutant. The chain length of the sap mutant can be reduced by the addition of purified BslO in the culture medium. This complementation in trans can be explained by an increased deposition of BslO onto the surface of sap mutant bacilli that extends beyond chain septa. Using fluorescence microscopy, we observed that the Sap S layer does not overlap the EA1 S layer and slowly yields to the EA1 S layer in a growth-phase-dependent manner. Although present all over bacilli, Sap S-layer patches are not observed at septa. Thus, we propose that the dynamic Sap/EA1 S-layer coverage of the envelope restricts the deposition of BslO to the SCWP at septal rings. PMID:22609927

  8. Bone-like apatite coating on functionalized poly(etheretherketone) surface via tailored silanization layers technique

    International Nuclear Information System (INIS)

    Zheng, Yanyan; Xiong, Chengdong; Zhang, Shenglan; Li, Xiaoyu; Zhang, Lifang

    2015-01-01

    Poly(etheretherketone) (PEEK) is a rigid semi-crystalline polymer with outstanding mechanical properties, bone-like stiffness and suitable biocompatibility that has attracted much interest as a biomaterial for orthopedic and dental implants. However, the bio-inert surface of PEEK limits its biomedical applications when direct osteointegration between the implants and the host tissue is desired. In this work, –PO 4 H 2 , –COOH and –OH groups were introduced on the PEEK surface by further chemical treatments of the vinyl-terminated silanization layers formed on the hydroxylation-pretreated PEEK surface. Both the surface-functionalized and pristine specimens were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and water contact angle measurements. When placed in 1.5 strength simulated body fluid (SBF) solution, apatite was observed to form uniformly on the functionalized PEEK surface and firmly attach to the substrate. The characterized results demonstrated that the coating was constituted by poorly crystallized bone-like apatite and the effect of surface functional groups on coating formation was also discussed in detail. In addition, in vitro biocompatibility of PEEK, in terms of pre-osteoblast cell (MC3T3-E1) attachment, spreading and proliferation, was remarkably enhanced by the bone-like apatite coating. Thus, this study provides a method to enhance the bioactivity of PEEK and expand its applications in orthopedic and dental implants. - Highlights: • –PO 4 H 2 , –COOH and –OH groups were successfully introduced onto PEEK surface via tailored silanization layer technique. • Bone-like apatite formed uniformly on surface-functionalized PEEK after immersion in SBF, and tightly adhered to the PEEK. • SEM, EDS, FTIR, XPS and XRD results showed that apatite layer is composed of low-crystalline bone-like apatite. • Bone-like apatite coating remarkably enhanced pre

  9. Bone-like apatite coating on functionalized poly(etheretherketone) surface via tailored silanization layers technique

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Yanyan [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Xiong, Chengdong; Zhang, Shenglan [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041 (China); Li, Xiaoyu [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Zhang, Lifang, E-mail: zhanglfcioc@163.com [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041 (China)

    2015-10-01

    Poly(etheretherketone) (PEEK) is a rigid semi-crystalline polymer with outstanding mechanical properties, bone-like stiffness and suitable biocompatibility that has attracted much interest as a biomaterial for orthopedic and dental implants. However, the bio-inert surface of PEEK limits its biomedical applications when direct osteointegration between the implants and the host tissue is desired. In this work, –PO{sub 4}H{sub 2}, –COOH and –OH groups were introduced on the PEEK surface by further chemical treatments of the vinyl-terminated silanization layers formed on the hydroxylation-pretreated PEEK surface. Both the surface-functionalized and pristine specimens were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and water contact angle measurements. When placed in 1.5 strength simulated body fluid (SBF) solution, apatite was observed to form uniformly on the functionalized PEEK surface and firmly attach to the substrate. The characterized results demonstrated that the coating was constituted by poorly crystallized bone-like apatite and the effect of surface functional groups on coating formation was also discussed in detail. In addition, in vitro biocompatibility of PEEK, in terms of pre-osteoblast cell (MC3T3-E1) attachment, spreading and proliferation, was remarkably enhanced by the bone-like apatite coating. Thus, this study provides a method to enhance the bioactivity of PEEK and expand its applications in orthopedic and dental implants. - Highlights: • –PO{sub 4}H{sub 2}, –COOH and –OH groups were successfully introduced onto PEEK surface via tailored silanization layer technique. • Bone-like apatite formed uniformly on surface-functionalized PEEK after immersion in SBF, and tightly adhered to the PEEK. • SEM, EDS, FTIR, XPS and XRD results showed that apatite layer is composed of low-crystalline bone-like apatite. • Bone-like apatite coating

  10. Stepping towards new parameterizations for non-canonical atmospheric surface-layer conditions

    Science.gov (United States)

    Calaf, M.; Margairaz, F.; Pardyjak, E.

    2017-12-01

    Representing land-atmosphere exchange processes as a lower boundary condition remains a challenge. This is partially a result of the fact that land-surface heterogeneity exists at all spatial scales and its variability does not "average" out with decreasing scales. Such variability need not rapidly blend away from the boundary thereby impacting the near-surface region of the atmosphere. Traditionally, momentum and energy fluxes linking the land surface to the flow in NWP models have been parameterized using atmospheric surface layer (ASL) similarity theory. There is ample evidence that such representation is acceptable for stationary and planar-homogeneous flows in the absence of subsidence. However, heterogeneity remains a ubiquitous feature eliciting appreciable deviations when using ASL similarity theory, especially in scalars such moisture and air temperature whose blending is less efficient when compared to momentum. The focus of this project is to quantify the effect of surface thermal heterogeneity with scales Ο(1/10) the height of the atmospheric boundary layer and characterized by uniform roughness. Such near-canonical cases describe inhomogeneous scalar transport in an otherwise planar homogeneous flow when thermal stratification is weak or absent. In this work we present a large-eddy simulation study that characterizes the effect of surface thermal heterogeneities on the atmospheric flow using the concept of dispersive fluxes. Results illustrate a regime in which the flow is mostly driven by the surface thermal heterogeneities, in which the contribution of the dispersive fluxes can account for up to 40% of the total sensible heat flux. Results also illustrate an alternative regime in which the effect of the surface thermal heterogeneities is quickly blended, and the dispersive fluxes provide instead a quantification of the flow spatial heterogeneities produced by coherent turbulent structures result of the surface shear stress. A threshold flow

  11. The structure of the NiTi surface layers after the ion-plasma alloying of Ta

    Energy Technology Data Exchange (ETDEWEB)

    Poletika, T. M., E-mail: poletm@ispms.tsc.ru; Girsova, S. L., E-mail: girs@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Meisner, L. L., E-mail: lm@ispms.tsc.ru; Meisner, S. N., E-mail: msn@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation); Schmidt, E. Yu., E-mail: shmidt.rin@yandex.ru [National Research Tomsk State University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    The effect of the Ta-ion beam implantation on the micro- and nanostructures of the surface layers of NiTi alloy was investigated using transmission electron microscopy and Auger spectroscopy. It is found that the elements are distributed non-uniformly with depth, so that the sublayers differ significantly in structure. The modified surface layer was found to consist of two sublayers, i.e. the upper oxide layer and the lower-lying amorphous layer that contains a maximum of Ta atoms.

  12. Successful implementation of the stepwise layer-by-layer growth of MOF thin films on confined surfaces: Mesoporous silica foam as a first case study

    KAUST Repository

    Shekhah, Osama

    2012-01-01

    Here we report the successful growth of highly crystalline homogeneous MOF thin films of HKUST-1 and ZIF-8 on mesoporous silica foam, by employing a layer-by-layer (LBL) method. The ability to control and direct the growth of MOF thin films on confined surfaces, using the stepwise LBL method, paves the way for new prospective applications of such hybrid systems. © 2012 The Royal Society of Chemistry.

  13. High-Sensitive Two-Layer Photoresistors Based on p-Cd x Hg1-x Te with a Converted Near-Surface Layer

    Science.gov (United States)

    Ismailov, N. D.; Talipov, N. Kh.; Voitsekhovskii, A. V.

    2018-04-01

    The results of an experimental study of photoelectric characteristics of two-layer photoresistors based on p-Cd x Hg1-x Te (x = 0.24-0.28) with a thin near-surface layer of n-type obtained by treatment in atmospheric gas plasma are presented. It is shown that the presence of a potential barrier between the p- and n-regions causes high photosensitivity and speed of operation of such photoresistors at T = 77 K

  14. Regulating spin and Fermi surface topology of a quantum metal film by the surface (interface) monatomic layer

    Science.gov (United States)

    Matsuda, Iwao

    2012-02-01

    Spin and current controls in solids have been one of the central issues in researches of electron and spin transport. Nowadays, electronics/spintronics deals with nanometer- or atomic-scale structures and miniaturization of these systems implies emergence of various quantum phenomena, intimately linked to the formation of electronic states different from those of the corresponding bulk materials. For example, valence electrons of films with the thickness comparable to the electron wavelength form discrete quantum-well states (QWSs) under opportune conditions of confinement (quantum size effect). Furthermore, the size reduction also increases the surface/volume ratio and a film possibly changes its electronic (spin) properties by the surface effect. Concerning metal films, the quantum size effect requires the thickness in a range of nanometers and the length corresponds to several tens of atoms, indicating the very large ratio of a surface (interface) monatomic layer to film atomic layers. Thus, we have been interested in combining the quantum size effects and the surface effect on the metal films to induce new physical phenomena. In the present talk, two research cases are shown. 1) Instead of isotropic two-dimensional in-plane states expected for an isolated metal film, quasi-one-dimensional quantized states were measured by photoemission spectroscopy in an epitaxial Ag(111) ultra thin film, prepared on an array of atomic chains [1]. 2) High-resolution spin-resolved photoemission and magneto-transport experiments of ultrathin Ag(111) films, covered with a /3x/3-Bi/Ag surface ordered alloy, were performed. The surface state (SS) bands, spin-split by the Rashba interaction, selectively couple to the originally spin-degenerate QWS bands in the metal film, making the spin-dependent hybridization [2,3]. Magnetoconductance of the films, measured in situ by the micro-four-point probe method as a function of the applied magnetic field [4], has shown that the formation of

  15. Dynamic change in the surface and layer structures during epitaxial growth of Si on a Si(111)-7x7 surface

    International Nuclear Information System (INIS)

    Fukaya, Y.; Shigeta, Y.; Maki, K.

    2000-01-01

    In order to investigate the dynamic process during growth of a Si layer on the Si(111)-7x7 surface held at 380 deg. C, the rocking curve of reflection high-energy electron diffraction (RHEED) is continuously measured at 0.5 deg. to 6 deg. at intervals of 0.05 deg. to the glancing angle of the incident electron beam which takes 18 sec. At the initial growth stage, the multilayer islands are grown on the native 7x7 surface with broader Bragg peaks in the rocking curve than those from the native surface. The sharpness of the Bragg peak is subsequently recovered after the thickness of the Si layer reaches 3 BL (1 BL=0.31 nm), at which the growth transforms to layer-by-layer growth. The comparison of the measured rocking curve with the calculated one based on the dynamical theory of RHEED intensity is also performed by optimizing each atomic position in the growing layer so as to minimize the difference between both curves. The space of the double layer of the (111) plane in the multilayer islands expands and is restored to the normal spacing after the growth mode transforms to the layer-by-layer mode. The broadening of the Bragg peaks at the initial growth stage relates to the rearrangement process of a stacking-fault layer in the 7x7 structure on the substrate surface

  16. Surface layers of Xanthomonas malvacearum, the cause of bacterial blight of cotton.

    Science.gov (United States)

    Verma, J P; Formanek, H

    1981-01-01

    Mureins were isolated from two strains of Xanthomonas malvacearum, a phytopathogenic bacterium causing bacterial blight of cotton. The purity of murein was 70-95 % and the amino acid and amino sugar components (glutamic acid, alanina, meso-disminopimelic acid, muramic acid and glucosamine) were present at the molar ratio of 1:1.9:1:l.12.0.85. The bacterium secreted a copious amount of slime which masked itd surface structure. The slime was composed of densley interwoven network of filamentous material originating from the cell surface and extended into the medium without and discernable boundary. The slime was secreted through surface layers pores by force, giving the effect of a spray or jet. Slime also played a role in chain formatin of baterial cells.

  17. Higher order reconstructions of the Ge(001) surface induced by a Ba layer

    Science.gov (United States)

    Koczorowski, W.; Grzela, T.; Puchalska, A.; Radny, M. W.; Jurczyszyn, L.; Schofield, S. R.; Czajka, R.; Curson, N. J.

    2018-03-01

    Structural properties of Ba-induced reconstructions on a Ge(001) surface, based on atomic-resolution ultra high-vacuum scanning tunneling microscopy measurements, are discussed. It is shown that while the Ba - Ge layer, which fully covers the surface, is dominated by a phase with an internal 2 × 3 periodicity, it also includes portions of higher order 2 × 6 and 4 × 3 surface reconstructions, always accompanied by 1D protrusions embedded into the dominating phase. Modelling the observed higher order structures, using the elementary cell of the 2 × 3 phase calculated within the density functional theory, is shown to reproduce the experimental data very well. As such the higher order reconstructions can be treated as local defects of the dominating 2 × 3 phase.

  18. Protective capping and surface passivation of III-V nanowires by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Dhaka, Veer, E-mail: veer.dhaka@aalto.fi; Perros, Alexander; Kakko, Joona-Pekko; Haggren, Tuomas; Lipsanen, Harri [Department of Micro- and Nanosciences, Micronova, Aalto University, P.O. Box 13500, FI-00076 (Finland); Naureen, Shagufta; Shahid, Naeem [Research School of Physics & Engineering, Department of Electronic Materials Engineering, Australian National University, Canberra ACT 2601 (Australia); Jiang, Hua; Kauppinen, Esko [Department of Applied Physics and Nanomicroscopy Center, Aalto University, P.O. Box 15100, FI-00076 (Finland); Srinivasan, Anand [School of Information and Communication Technology, KTH Royal Institute of Technology, Electrum 229, S-164 40 Kista (Sweden)

    2016-01-15

    Low temperature (∼200 °C) grown atomic layer deposition (ALD) films of AlN, TiN, Al{sub 2}O{sub 3}, GaN, and TiO{sub 2} were tested for protective capping and surface passivation of bottom-up grown III-V (GaAs and InP) nanowires (NWs), and top-down fabricated InP nanopillars. For as-grown GaAs NWs, only the AlN material passivated the GaAs surface as measured by photoluminescence (PL) at low temperatures (15K), and the best passivation was achieved with a few monolayer thick (2Å) film. For InP NWs, the best passivation (∼2x enhancement in room-temperature PL) was achieved with a capping of 2nm thick Al{sub 2}O{sub 3}. All other ALD capping layers resulted in a de-passivation effect and possible damage to the InP surface. Top-down fabricated InP nanopillars show similar passivation effects as InP NWs. In particular, capping with a 2 nm thick Al{sub 2}O{sub 3} layer increased the carrier decay time from 251 ps (as-etched nanopillars) to about 525 ps. Tests after six months ageing reveal that the capped nanostructures retain their optical properties. Overall, capping of GaAs and InP NWs with high-k dielectrics AlN and Al{sub 2}O{sub 3} provides moderate surface passivation as well as long term protection from oxidation and environmental attack.

  19. Protective capping and surface passivation of III-V nanowires by atomic layer deposition

    Directory of Open Access Journals (Sweden)

    Veer Dhaka

    2016-01-01

    Full Text Available Low temperature (∼200 °C grown atomic layer deposition (ALD films of AlN, TiN, Al2O3, GaN, and TiO2 were tested for protective capping and surface passivation of bottom-up grown III-V (GaAs and InP nanowires (NWs, and top-down fabricated InP nanopillars. For as-grown GaAs NWs, only the AlN material passivated the GaAs surface as measured by photoluminescence (PL at low temperatures (15K, and the best passivation was achieved with a few monolayer thick (2Å film. For InP NWs, the best passivation (∼2x enhancement in room-temperature PL was achieved with a capping of 2nm thick Al2O3. All other ALD capping layers resulted in a de-passivation effect and possible damage to the InP surface. Top-down fabricated InP nanopillars show similar passivation effects as InP NWs. In particular, capping with a 2 nm thick Al2O3 layer increased the carrier decay time from 251 ps (as-etched nanopillars to about 525 ps. Tests after six months ageing reveal that the capped nanostructures retain their optical properties. Overall, capping of GaAs and InP NWs with high-k dielectrics AlN and Al2O3 provides moderate surface passivation as well as long term protection from oxidation and environmental attack.

  20. Airborne Measurement of Insolation Impact on the Atmospheric Surface Boundary Layer

    Science.gov (United States)

    Jacob, Jamey; Chilson, Phil; Houston, Adam; Detweiler, Carrick; Bailey, Sean; Cloud-Map Team

    2017-11-01

    Atmospheric surface boundary layer measurements of wind and thermodynamic parameters are conducted during variable insolation conditions, including the 2017 eclipse, using an unmanned aircraft system. It is well known that the air temperatures can drop significantly during a total solar eclipse as has been previously observed. In past eclipses, these observations have primarily been made on the ground. We present results from airborne measurements of the near surface boundary layer using a small unmanned aircraft with high temporal resolution wind and thermodynamic observations. Questions that motivate the study include: How does the temperature within the lower atmospheric boundary vary during an eclipse? What impact does the immediate removal of radiative heating on the ground have on the lower ABL? Do local wind patterns change during an eclipse event and if so why? Will there be a manifestation of the nocturnal boundary layer wind maximum? Comparisons are made with the DOE ARM SGP site that experiences a lower but still significant insolation. Supported by the National Science Foundation under Award Number 1539070.

  1. Characterization of the bacterial community associated with the surface and mucus layer of whiting (Merlangius merlangus).

    Science.gov (United States)

    Smith, Cindy J; Danilowicz, Bret S; Meijer, Wim G

    2007-10-01

    The bacterial community inhabiting the mucus layer and surface of whiting was examined to determine whether the bacteria present are a reflection of the surrounding water or an indigenous bacterial flora is present. The outer mucus, mouth mucus and gut of four whiting harvested from a site in the Irish Sea and the surrounding water were examined by terminal restriction fragment length polymorphism (tRFLP) analysis of the 16S rRNA gene and clone library construction. The water community was the most diverse, with only a small number of shared water-mucus phylotypes present. The bacterial flora associated with the outer mucus layer were more diverse than that of the mouth mucus and gut. All three mucus layers were characterized by the presence of a dominant phylotype, identified as clone wom-1, highly similar to Photobacterium iliopiscarium. In addition to other Photobacterium phylotypes, members of the CFB and Clostridia groups were also detected. Subsequently, whiting from 11 different sites along the east and south coast of Ireland were compared by tRFLP analysis. Strikingly, the mucus layer of whiting at all sites was characterized by the presence and dominance of a TRF corresponding to the clone wom-1 which was virtually absent from the water column.

  2. Threshold voltages and optical retardation of deformed flexoelectric nematic layers with asymmetric surface anchoring

    Science.gov (United States)

    Derfel, G.; Buczkowska, M.

    2013-06-01

    Deformations of homeotropically aligned flexoelectric nematic layers induced by dc electric fields were simulated numerically. Two different anchoring strengths on the limiting surfaces were assumed. Nematic material was characterised by negative dielectric anisotropy. Both signs of the sum of flexoelectric coefficients were taken into account. The electric properties of the layer were described in terms of a weak electrolyte model. Mobility of cations was assumed to be one order of magnitude lower than that of anions. Quasi-blocking electrode contacts were assumed. The threshold voltages for deformations were determined by means of calculations of the phase difference Φ between ordinary and extraordinary light rays passing through a layer placed between crossed polarisers. The threshold values depended on the polarity of the bias voltage U. When the threshold value was exceeded, the phase difference increased with the voltage. Two different Φ(U/Uthreshold) dependencies for the two polarities of the voltage were found for each layer if the nematic possessed the flexoelectric properties. The possibility of using this effect to detect the flexoelectricity in the nematic was explored by simulated experiments. The effectiveness of the proposed method is discussed.

  3. Implementation of guiding layers of surface acoustic wave devices: A review.

    Science.gov (United States)

    Xu, Zhangliang; Yuan, Yong J

    2018-01-15

    The purpose of overviewing research and development status of dependable, efficient, and portable and miniaturized surface acoustic wave (SAW) is to propose practical devices for biosensing and medical diagnosis. SAW Love-mode sensors fortunately have a great deal of attention during last two decades. Several periodic structure models of SAW devices were reviewed, especially interdigital transducers (IDTs), wave guiding layers, patterned-ZnO. SAW devices based on such periodic wave guiding layers and patterned-ZnO were demonstrated with superior performance, much better than conventional SAW devices. Both 2D and 3D models of phononic-crystal-based SAW devices can be respectively fabricated by an array of periodic cylindrical holes and pillars, which allowed SAW devices to have both higher Q-factor and GHz-level frequency. Ring waveguide and spherical SAW devices would have potential applications and implementation in biosensing. ZnO is one of attractive guiding-layer materials. Its nanostructures, such as nanowires, nanorods and nanofibers provided with excellent properties, will make nanoscaled SAW devices contribute to be much more sensitive in biosensors. A range of applications based on SAW and ZnO guiding-layer would be therefore expected among of immunochemical analysis, in-situ virus or bacteria determination, microfluidic automation, and cell manipulation. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Factors Influencing Social, Cultural, and Academic Transitions of Chinese International ESL Students in U.S. Higher Education

    Science.gov (United States)

    Ota, Akiko

    2013-01-01

    The U.S. is the leading nation for international students to pursue higher education; the majority of whom are from countries with significant differences in culture and language from American students. As such, many international students start higher education in ESL support programs. While on the surface international students supposedly add…

  5. Immunity of Surface Layer Protein of Aeromonas ‎hydrophila in Rabbits

    Directory of Open Access Journals (Sweden)

    Lobna Adil Al-Noori

    2017-11-01

    Full Text Available In this study the Surface layer (S-layer protein was extracted from Aeromonas hydrophila bacteria ,the humoral immune response that induced by S-layer protein only or as adjuvant was investigated  by using 16 males New Zealand rabbits and divided into four groups, each group contained four rabbits, the first group was immunized with  S-layer protein only, the second group was immunized with heated killed antigen(HKAof Sallmonella typhi only, the third group was immunized with mixed antigens (S-layer+ HKA,while the fourth group considered as control group and immunized with normal saline. The HKA of S. typhi  was used to evaluate the efficiency of S-layer protein as adjuvant. After the immunization period, the humoral immune response was investigated by several tests include, tube agglutination test and passive agglutination test that used to detect the antibody titer. Biuret method was used to determine the total protein concentration in serum  samples and total protein concentration of secretory immunoglobulin that extracted form appendix samples. In addition the Radical Immunodiffution (RID  method was used to detect the concentration level of the IgG in serum samples. Moreover the concentration level of the CD4 in the serum samples was determined by enzyme linked immunosorbent assay (ELISA method .In all these tests the result revealed, both of S-layer protein only , HKA of only and mixed antigens(S-layer+ HKA were given significantly increased in comparison with control group at P<0.05. The result showed that the  concentration level of IgG with mean values (2365.5 , 3505 and 2916 mg/dl respectively  while the control group with mean value (1662mg/dl. In addition the concentration  level of CD4 molecule with mean values (9.37, 11.77 and 17.36 ng/ml respectively while the control group with mean value (6.91 ng/ml .The results showed that these three types of antigens induced the humoral immune response

  6. Surface coating for flame-retardant behavior of cotton fabric using a continuous layer-by-layer process

    Science.gov (United States)

    Cotton’s exceptional softness, breathability, and absorbency have made it America’s best selling textile fiber; however, cotton textiles are generally more combustible than their synthetic counterparts. In this study, a continuous layer-by-layer self-assembly technique was used to deposit polymer-cl...

  7. Ensemble based Assimilation of SMOS Surface Soil Moisture into the Surfex 11-layer Diffusion Scheme

    Science.gov (United States)

    Blyverket, Jostein; Hamer, Paul; Svendby, Tove; Lahoz, William

    2017-04-01

    The Soil Moisture and Ocean Salinity (SMOS) satellite samples soil moisture at a spatial scale of ˜40 km and in the top ˜5 cm of the soil, depending on land cover and soil type. Remote sensing products have a limited spatial and temporal cover, with a re-visit time of 3 days close to the Equator for SMOS. These factors make it difficult to monitor the hydrological cycle over e.g., Northern Areas where there is a strong topography, fractal coastline and long periods of snow cover, all of which affect the SMOS soil moisture retrieval. Until now simple 3-layer force and restore models have been used to close the spatial (vertical/horizontal) and temporal gaps of soil moisture from remote sensing platforms. In this study we have implemented the Ensemble Transform Kalman Filter (ETKF) into the Surfex land surface model, and used the ISBA diffusion scheme with 11-vertical layers. In contrast to the rapid changing surface layer, the slower changing root zone soil moisture is important for long term evapotranspiration and water supply. By combining a land surface model with satellite observations using data assimilation we can provide a better estimate of the root zone soil moisture at regional scales. The Surfex model runs are done for a European domain, from 1 July 2012 to 1 August 2013. For validation of our model setup, we compare with in situ stations from the International Soil Moisture Network (ISMN) and the Norwegian Water and Energy Authorities (NVE); we also compare against the ESA CCI soil moisture product v02.2, which does not include SMOS soil moisture data. SMOS observations and open loop model runs are shown to exhibit large biases, these are removed before assimilation by a linear rescaling technique. Information from the satellite is transferred into deeper layers of the model using data assimilation, improving the root zone product when validated against in situ stations. The improved correlation between the assimilated product and the in situ values

  8. Tribochemical interaction between nanoparticles and surfaces of selective layer during chemical mechanical polishing

    Energy Technology Data Exchange (ETDEWEB)

    Ilie, Filip, E-mail: filip@meca.omtr.pub.ro [Polytechnic University of Bucharest, Department of Machine Elements and Tribology (Romania)

    2013-11-15

    Nanoparticles have been widely used in polish slurries such as those in the chemical mechanical polishing (CMP) process. For understanding the mechanisms of CMP, an atomic force microscope (AFM) is used to characterize polished surfaces of selective layers, after a set of polishing experiments. To optimize the CMP polishing process, one needs to get information on the interaction between the nano-abrasive slurry nanoparticles and the surface of selective layer being polished. The slurry used in CMP process of the solid surfaces is slurry with large nanoparticle size colloidal silica sol nano-abrasives. Silica sol nano-abrasives with large nanoparticle are prepared and characterized by transmission electron microscopy, particles colloidal size, and Zeta potential in this paper. The movement of nanoparticles in liquid and the interaction between nanoparticles and solid surfaces coating with selective layer are very important to obtain an atomic alloy smooth surface in the CMP process. We investigate the nanoparticle adhesion and removal processes during CMP and post-CMP cleaning. The mechanical interaction between nanoparticles and the wafer surface was studied using a microcontact wear model. This model considers the nanoparticle effects between the polishing interfaces during load balancing. Experimental results on polishing and cleaning are compared with numerical analysis. This paper suggests that during post-CMP cleaning, a combined effort in chemical and mechanical interaction (tribochemical interactions) would be effective in removal of small nanoparticles during cleaning. For large nanoparticles, more mechanical forces would be more effective. CMP results show that the removal rate has been improved to 367 nm/min and root mean square (RMS) of roughness has been reduced from 4.4 to 0.80 nm. Also, the results show that the silica sol nano-abrasives about 100 nm are of higher stability (Zeta potential is −65 mV) and narrow distribution of nanoparticle

  9. Extended verification of the model of dynamic near-surface layer of the atmosphere

    Science.gov (United States)

    Polnikov, V. G.

    2013-07-01

    This paper formulates the most general principles for verifying models of the dynamic near-water layer of the atmosphere (DNWLA) and performs an advanced verification of the model proposed by the author earlier [6]. Based on empirical wave spectra from the studies by Donelan [15], Elfouhaily [14], and Kudryavtsev [13] and well-known empirical laws describing the wave-age dependence of the friction coefficient, we adjusted the original version of the model. It was shown that the improvement of model reliability is most dependent on the adequacy of the parameterization of the tangential portion of the total momentum flux to the wavy surface. Then the new version of the model was verified on the basis of field data from two different groups of authors. It was found that the new version of the model is consistent with empirical data with an error not exceeding the measurement error of near-water layer parameters.

  10. Surface-Induced Near-Field Scaling in the Knudsen Layer of a Rarefied Gas

    Science.gov (United States)

    Gazizulin, R. R.; Maillet, O.; Zhou, X.; Cid, A. Maldonado; Bourgeois, O.; Collin, E.

    2018-01-01

    We report on experiments performed within the Knudsen boundary layer of a low-pressure gas. The noninvasive probe we use is a suspended nanoelectromechanical string, which interacts with He 4 gas at cryogenic temperatures. When the pressure P is decreased, a reduction of the damping force below molecular friction ∝P had been first reported in Phys. Rev. Lett. 113, 136101 (2014), 10.1103/PhysRevLett.113.136101 and never reproduced since. We demonstrate that this effect is independent of geometry, but dependent on temperature. Within the framework of kinetic theory, this reduction is interpreted as a rarefaction phenomenon, carried through the boundary layer by a deviation from the usual Maxwell-Boltzmann equilibrium distribution induced by surface scattering. Adsorbed atoms are shown to play a key role in the process, which explains why room temperature data fail to reproduce it.

  11. Sensitivity enhancement of a surface plasmon resonance sensor using porous metamaterial layers

    Science.gov (United States)

    Cherifi, Abdellatif; Bouhafs, Benamar

    2017-12-01

    In this work, the surface plasmon resonance (SPR) device with two porous left handed metamaterial (LHM) layers separated by an insulator gap, is investigated. The effect of the insulator gap thickness and its refractive index (RI) on the angular response of the device is analyzed. The results show that the sensitivity of the SPR sensor is enhanced compared to the standard SPR sensors. Here, the multilayer structure is probed with 738 nm-wavelength, and electromagnetic properties of active porous LHM layers are described from the effective medium theory (EMT). Furthermore, in the increase of the porosity from 0 to 0.6, the designed nanocavity exhibits a fundamental SPR mode long-range (LR) type and it can be of interest in high-performance SPR sensing.

  12. Hardness optimization of boride diffusion layer on Astm F-75 alloy using response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Arguelles O, J. L.; Corona R, M. A. [Universidad Autonoma de San Luis Potosi, Doctorado Institucional en Ingenieria y Ciencia de Materiales, San Luis Potosi 78000, SLP (Mexico); Marquez H, A.; Saldana R, A. L.; Saldana R, A. [Universidad de Guanajuato, Ingenieria Mecanica Agricola DICIVA, Irapuato, Guanajuato 36500 (Mexico); Moreno P, J., E-mail: amarquez@ugto.mx [Universidad de Guanajuato, Departamento de Minas, Metalurgia y Geologia, Ex-Hacienda San Matias s/n, Guanajuato, Guanajuato 36020 (Mexico)

    2017-11-01

    In this study, the Response Surface Methodology (Rsm) and Central Composite Design (Ccd) were used to optimize the hardness of boride diffusion layer on Astm F-75 alloy (also called Haynes alloy). A boronizing thermochemical treatment was carried out at different temperatures and for different time periods. Hardness tests were conducted. The boride diffusion layer was verified by the X-ray diffraction (XRD) analysis indicating the formation of Co B, Co{sub 2}B, Cr B and Mo{sub 2}B phases. An optimal hardness of 3139.7 Hv was obtained for the samples subjected to the boriding process for a duration of 6.86 h at 802.4 degrees Celsius. (Author)

  13. The Analyses of Turbulence Characteristics in the Atmospheric Surface Layer Using Arbitrary-Order Hilbert Spectra

    Science.gov (United States)

    Wei, W.; Schmitt, F. G.; Huang, Y. X.; Zhang, H. S.

    2016-05-01

    Turbulent characteristics in the atmospheric surface layer are investigated using a data-driven method, Hilbert spectral analysis. The results from empirical mode decomposition display a set of intrinsic mode functions whose characteristic scales suggest a dyadic filter-bank property. It can be concluded from the joint probability density function of the intrinsic mode functions that the turbulent properties are totally different under different stratifications: the amplitudes (or energies) are arranged according to the stability parameter [InlineEquation not available: see fulltext.] for stable conditions, but tend to cluster randomly for unstable cases. The intermittency analyses reveal that second-order Hilbert marginal spectra display a power-law behaviour in the inertial subrange, and that the scaling exponent functions deviate from the theoretical values due to the strong intermittency in the stable boundary layer.

  14. Composition of Surface Adsorbed Layer of TiO2 Stored in Ambient Air

    Directory of Open Access Journals (Sweden)

    Zakharenko V.S.

    2017-11-01

    Full Text Available The processes of dark, UV, and visible light promoted desorption of surface species were investigated for three different TiO2 samples: TiO2 prepared by dispersion of the titania single crystal, TiO2 prepared by combustion of a pyrotechnic mixture in air, and commercial TiO2 P25. The composition of the adsorbed layer was identified in the dark and under UV and visible light irradiation. The composition of desorption products showed the dependence of the adsorption layer state on the TiO2 nature. Methane photodesorption was detected only for the commercial TiO2 P25. Possible reasons for methane emission include the capturing of complete molecules during the TiO2 production process and photocatalytic hydrogenation of CO2 under UV-light.

  15. Hardness optimization of boride diffusion layer on Astm F-75 alloy using response surface methodology

    International Nuclear Information System (INIS)

    Arguelles O, J. L.; Corona R, M. A.; Marquez H, A.; Saldana R, A. L.; Saldana R, A.; Moreno P, J.

    2017-01-01

    In this study, the Response Surface Methodology (Rsm) and Central Composite Design (Ccd) were used to optimize the hardness of boride diffusion layer on Astm F-75 alloy (also called Haynes alloy). A boronizing thermochemical treatment was carried out at different temperatures and for different time periods. Hardness tests were conducted. The boride diffusion layer was verified by the X-ray diffraction (XRD) analysis indicating the formation of Co B, Co 2 B, Cr B and Mo 2 B phases. An optimal hardness of 3139.7 Hv was obtained for the samples subjected to the boriding process for a duration of 6.86 h at 802.4 degrees Celsius. (Author)

  16. Surface photovoltage method for the quality control of silicon epitaxial layers on sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Yaremchuk, A. F.; Starkov, A. V.; Zaikin, A. V., E-mail: lynch0000@gmail.com [National Rsearch University MIET (Russian Federation); Alekseev, A. V. [ZAO “Telekom-STV” (Russian Federation); Sokolov, E. M. [ZAO “Epiel” (Russian Federation)

    2014-12-15

    The surface photovoltage method is used to study “silicon-on-sapphire” epitaxial layers with a thickness of 0.3–0.6 μm, which are used to fabricate p-channel MOS (metal—oxide-semiconductor) transistors with improved radiation hardness. It is shown that the manner in which the photoconductivity of the epitaxial layer decays after the end of a light pulse generated by a light-emitting diode (wavelength ∼400 nm) strongly depends on the density of structural defects in the bulk of the structure. This enables control over how a “silicon-on-sapphire” structure is formed to provide the manufacturing of MOS structures with optimal operating characteristics.

  17. Native SrTiO3 (001) surface layer from resonant Ti L2,3 reflectance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Valvidares, Manuel; Huijben, Mark; Yu, Pu; Ramesh, Ramamoorthy; Kortright, Jeffrey

    2010-11-03

    We quantitatively model resonant Ti L2,3 reflectivity Rs,p(q, hn) from several SrTiO3 (001) single crystals having different initial surface preparations and stored in ambient conditions before and between measurements. All samples exhibit unexpected 300 K Rs(hn) - Rp(hn) anisotropy corresponding to weak linear dichroism and tetragonal distortion of the TiO6 octahedra indicating a surface layer with properties different from cubic SrTiO3. Oscillations in Rs(q) confirm a ubiquitous surface layer 2-3 nm thick that evolves over a range of time scales. Resonant optical constant spectra derived from Rs,p(hn) assuming a uniform sample are refined using a single surface layer to fit measured Rs(q). Differences in surface layer and bulk optical properties indicate that the surface is significantly depleted in Sr and enriched in Ti and O. While consistent with the tendency of SrTiO3 surfaces toward non-stoichiometry, this layer does not conform simply to existing models for the near surface region and apparently forms via room temperature surface reactions with the ambient. This new quantitative spectral modeling approach is generally applicable and has potential to study near-surface properties of a variety of systems with unique chemical and electronic sensitivities.

  18. Nanoscale surface modification of Li-rich layered oxides for high-capacity cathodes in Li-ion batteries

    Science.gov (United States)

    Lan, Xiwei; Xin, Yue; Wang, Libin; Hu, Xianluo

    2018-03-01

    Li-rich layered oxides (LLOs) have been developed as a high-capacity cathode material for Li-ion batteries, but the structural complexity and unique initial charging behavior lead to several problems including large initial capacity loss, capacity and voltage fading, poor cyclability, and inferior rate capability. Since the surface conditions are critical to electrochemical performance and the drawbacks, nanoscale surface modification for improving LLO's properties is a general strategy. This review mainly summarizes the surface modification of LLOs and classifies them into three types of surface pre-treatment, surface gradient doping, and surface coating. Surface pre-treatment usually introduces removal of Li2O for lower irreversible capacity while surface doping is aimed to stabilize the structure during electrochemical cycling. Surface coating layers with different properties, protective layers to suppress the interface side reaction, coating layers related to structural transformation, and electronic/ionic conductive layers for better rate capability, can avoid the shortcomings of LLOs. In addition to surface modification for performance enhancement, other strategies can also be investigated to achieve high-performance LLO-based cathode materials.

  19. The OSMOSIS Model of the Wind-Driven Ocean Surface Boundary Layer.

    Science.gov (United States)

    Grant, A. L.; Belcher, S. E.; Pearson, B.; Polton, J.

    2016-02-01

    In the wind-driven ocean surface boundary layer (OSBL) the vertical velocity variance is observed to be larger than in shear driven turbulence. The observed variances are consistent with the results from large-eddy simulations (LES) which parametrize the interaction between the Stokes drift of the surface waves and vorticity. The resulting flow is known as Langmuir turbulence and the close connection between winds and waves suggests that Langmuir turbulence is common in the OSBL. This poster describes a model of the OSBL, developed as part of the OSMOSIS project, in which mixing is by Langmuir turbulence. The transports of momentum, heat and salinity are represented by a first-order closure scheme with flux-gradient relationships that include non-gradient contributions. In this the model is similar to the KPP scheme which uses flux-gradient relationships with non-gradient contributions to represent scalar transports. The flux-gradient relationships are derived from an analysis of the turbulent flux budgets of momentum and scalars (heat) obtained from LES. The non-gradient terms represent the contributions to the turbulent flux by the terms in the turbulent flux budget that represent the effects of the Stokes shear, buoyancy and turbulent transport. The eddy viscosity, diffusivities and non-gradient components are represented by similarity profiles. The depth of the boundary layer is determined by a prognostic equation, which represents the time variation of the boundary layer depth in both unstable and stable conditions. It is based on the equation for the depth integrated potential energy combined with a parametrization of the turbulent kinetic energy budget. The use of the prognostic equation allows the effects of Langmuir turbulence on boundary layer depth to be explicitly represented in the model. Comparison with the results from LES of the diurnal cycle of the OSBL are presented as a test for the model.

  20. Surface plasmon resonance investigation of optical detection in plasma-modified phospholipid layers

    Energy Technology Data Exchange (ETDEWEB)

    Park, Byoungchoo; Cho, Chanyoun; Choi, Kyoungho; Jeon, Honggoo [Kwangwoon University, Seoul (Korea, Republic of)

    2012-03-15

    We herein report on a study of surface plasmon resonance (SPR) in thin gold (Au) films coated with thin layers of phospholipid material, which had been exposed to an atmospheric pressure (AP) plasma containing both pure Ar and Ar mixed with O{sub 2} (Ar/O{sub 2}, 0.8%). The phospholipid material that we used for the SPR experiments was lecithin, and the AP plasma system was applied in air by means of a radio-frequency (RF) plasma generator. A thin (∼60 nm) film of Au and a thin (∼15 nm) layer of lecithin were deposited and attached to the face of a prism, and surface plasmon modes were excited along the interfaces of the prism-Au-lecithin-air system by means of prism coupling using a He-Ne Laser (632.8 nm). The experimental SPR reflectance curves of the Au-lecithin-air modes were found to be shifted towards those of the Au-air mode with increasing applications of AP RF plasma treatment. From the shifts in the SPR curves, we found that the estimated thickness of the lecithin layer treated with a pure Ar plasma showed a linear decrease with etching rate of about 3 nm per treatment while the thickness of the lecithin layer treated with a mixed Ar/O{sub 2} plasma showed a tendency to saturate following a large initial decrease (ca. 14 nm). All these results demonstrate that the use of SPR sensing could facilitate the detection of extremely small variations in plasma-treated films of biomaterials.

  1. Characterize Cold Bituminous Emulsion Mixtures Incorporated Ordinary Portland Cement Filler for Local Surface Layer

    Directory of Open Access Journals (Sweden)

    Mustafa Amoori Kadhim

    2018-02-01

    Full Text Available Cold Bituminous Emulsion Mixtures have many environmental, logistical, and economic advantages over conventional Hot Mix Asphalt. Nevertheless, their inferior performance and high water sensitivity at early life attract little attentions. Moreover, it is impossible to apply CBEM as a structural surface layer if left without treatment or enhancement. The main aim of this study is to enhance the properties of CBEM for the hope of using it as a structural layer. Thus, a trial has been made to improve CBEM mechanical and durability properties by replacing the Ordinary Portland Cement by the Conventional Mineral Filler with 3 percentages; namely, 0, 50%, and 100%. CBEM mixtures mechanical properties were evaluated in term of Marshall Stability and Flow, Indirect Tensile Strength, and Wheel Track Test. While Moisture damage was evaluated in terms of Retained Marshall Stability. Test results showed that the addition of 100%OPC filler can improve CBEM mechanical and durability properties efficiently. In terms of mechanical properties results, CBEM comprised 100%OPC, can be used as a structural Surface layer based on local Iraqi specifications limits, where mixture enhanced about 1.9, 1.78, 9,4.85, and 2.6  times in term of MS, MF, rutting deformation resistance, resistance to tensile cracking, and moisture damage resistance, respectively as compared to untreated CBEM. Also, CBEM-100%OPC mix seemed comparable (and sometime superior to HMA, e.g., resistance to rutting of CBEM is about 6.2 times higher than that of HMA. It’s worth to say that OPC upgrades CBEM to a significant level that enables it to use as a structural layer in terms of the mechanical and the durability properties.

  2. Smartphones Promote Autonomous Learning in ESL Classrooms

    Directory of Open Access Journals (Sweden)

    Viji Ramamuruthy

    2015-10-01

    Full Text Available The rapid development of high-technology has caused new inventions of gadgets for all walks of life regardless age. In this rapidly advancing technology era many individuals possess hi-tech gadgets such as laptops, tablets, iPad, android phones and smart phones. Adult learners in higher learning institution especially are fond of using smart phones. Students become passive in the classrooms as they are glued to their smart phones. This situation triggers the question of whether learning really takes place while the students are too engaged with their smart phones in the ESL classroom. In this context, the following questions are framed to investigate this issue: What type of learning skills are gained by using smartphones in ESL classrooms? Does smartphone use promote the autonomous learning process? To what extent do learners rely on the lecturers in addition to the usage of smartphones? What are the learning satisfactions gained by ESL learners using smartphones? A total of 70 smartphone users in the age range 18 to 26 years participated in this quantitative study. Questionnaires eliciting demographic details of the respondents, learning skills, learning satisfaction, students' perception on teacher's role in the ESL classroom and autonomous learning were distributed to all the randomly chosen samples. The data were then analyzed by using SPSS version 16. The findings revealed that smartphone use boosted learners’ critical thinking, creative thinking, communication and collaboration skills. In fact, learners gain great satisfaction in the learning process through smartphones. Although learners have moved toward autonomous learning, they are still reliant on the teachers to achieve their learning goals.

  3. Preservation of the Pt(100) surface reconstruction after growth of a continuous layer of graphene

    DEFF Research Database (Denmark)

    Nilsson, Louis; Andersen, Mie; Bjerre, Jacob

    2012-01-01

    Scanning tunneling microscopy shows that a layer of graphene can be grown on the hex-reconstructed Pt(100) surface and that the reconstruction is preserved after growth. A continuous sheet of graphene can be grown across domain boundaries and step edges without loss of periodicity or change in di...... to accommodation of edge dislocations. The defect formation energy and the induced buckling of the graphene have been characterized by DFT calculations.......Scanning tunneling microscopy shows that a layer of graphene can be grown on the hex-reconstructed Pt(100) surface and that the reconstruction is preserved after growth. A continuous sheet of graphene can be grown across domain boundaries and step edges without loss of periodicity or change...... in direction. Density functional theory calculations on a simple model system support the observation that the graphene can have different rotation angles relative to the hex-reconstructed Pt surface. The graphene sheet direction can be changed by incorporating pentagon-heptagon defects giving rise...

  4. Atomic layer deposition in nanostructured photovoltaics: tuning optical, electronic and surface properties

    Science.gov (United States)

    Palmstrom, Axel F.; Santra, Pralay K.; Bent, Stacey F.

    2015-07-01

    Nanostructured materials offer key advantages for third-generation photovoltaics, such as the ability to achieve high optical absorption together with enhanced charge carrier collection using low cost components. However, the extensive interfacial areas in nanostructured photovoltaic devices can cause high recombination rates and a high density of surface electronic states. In this feature article, we provide a brief review of some nanostructured photovoltaic technologies including dye-sensitized, quantum dot sensitized and colloidal quantum dot solar cells. We then introduce the technique of atomic layer deposition (ALD), which is a vapor phase deposition method using a sequence of self-limiting surface reaction steps to grow thin, uniform and conformal films. We discuss how ALD has established itself as a promising tool for addressing different aspects of nanostructured photovoltaics. Examples include the use of ALD to synthesize absorber materials for both quantum dot and plasmonic solar cells, to grow barrier layers for dye and quantum dot sensitized solar cells, and to infiltrate coatings into colloidal quantum dot solar cell to improve charge carrier mobilities as well as stability. We also provide an example of monolayer surface modification in which adsorbed ligand molecules on quantum dots are used to tune the band structure of colloidal quantum dot solar cells for improved charge collection. Finally, we comment on the present challenges and future outlook of the use of ALD for nanostructured photovoltaics.

  5. Atomic layer deposition in nanostructured photovoltaics: tuning optical, electronic and surface properties.

    Science.gov (United States)

    Palmstrom, Axel F; Santra, Pralay K; Bent, Stacey F

    2015-08-07

    Nanostructured materials offer key advantages for third-generation photovoltaics, such as the ability to achieve high optical absorption together with enhanced charge carrier collection using low cost components. However, the extensive interfacial areas in nanostructured photovoltaic devices can cause high recombination rates and a high density of surface electronic states. In this feature article, we provide a brief review of some nanostructured photovoltaic technologies including dye-sensitized, quantum dot sensitized and colloidal quantum dot solar cells. We then introduce the technique of atomic layer deposition (ALD), which is a vapor phase deposition method using a sequence of self-limiting surface reaction steps to grow thin, uniform and conformal films. We discuss how ALD has established itself as a promising tool for addressing different aspects of nanostructured photovoltaics. Examples include the use of ALD to synthesize absorber materials for both quantum dot and plasmonic solar cells, to grow barrier layers for dye and quantum dot sensitized solar cells, and to infiltrate coatings into colloidal quantum dot solar cell to improve charge carrier mobilities as well as stability. We also provide an example of monolayer surface modification in which adsorbed ligand molecules on quantum dots are used to tune the band structure of colloidal quantum dot solar cells for improved charge collection. Finally, we comment on the present challenges and future outlook of the use of ALD for nanostructured photovoltaics.

  6. Layered insulator hexagonal boron nitride for surface passivation in quantum dot solar cell

    International Nuclear Information System (INIS)

    Shanmugam, Mariyappan; Jain, Nikhil; Jacobs-Gedrim, Robin; Yu, Bin; Xu, Yang

    2013-01-01

    Single crystalline, two dimensional (2D) layered insulator hexagonal boron nitride (h-BN), is demonstrated as an emerging material candidate for surface passivation on mesoporous TiO 2 . Cadmium selenide (CdSe) quantum dot based bulk heterojunction (BHJ) solar cell employed h-BN passivated TiO 2 as an electron acceptor exhibits photoconversion efficiency ∼46% more than BHJ employed unpassivated TiO 2 . Dominant interfacial recombination pathways such as electron capture by TiO 2 surface states and recombination with hole at valence band of CdSe are efficiently controlled by h-BN enabled surface passivation, leading to improved photovoltaic performance. Highly crystalline, confirmed by transmission electron microscopy, dangling bond-free 2D layered h-BN with self-terminated atomic planes, achieved by chemical exfoliation, enables efficient passivation on TiO 2 , allowing electronic transport at TiO 2 /h-BN/CdSe interface with much lower recombination rate compared to an unpassivated TiO 2 /CdSe interface

  7. Study of the Mechanical Properties of a Nanostructured Surface Layer on 316L Stainless Steel

    Directory of Open Access Journals (Sweden)

    F. C. Lang

    2016-01-01

    Full Text Available A nanostructured surface layer (NSSL was generated on a 316L stainless steel plate through surface nanocrystallization (SNC. The grains of the surface layer were refined to nanoscale after SNC treatment. Moreover, the microstructure and mechanical properties of NSSL were analyzed with a transmission electron microscope (TEM and scanning electron microscope (SEM, through nanoindentation, and through reverse analysis of finite element method (FEM. TEM results showed that the grains in the NSSL measured 8 nm. In addition, these nanocrystalline grains took the form of random crystallographic orientation and were roughly equiaxed in shape. In situ SEM observations of the tensile process confirmed that the motions of the dislocations were determined from within the material and that the motions were blocked by the NSSL, thus improving overall yielding stress. Meanwhile, the nanohardness and the elastic modulus of the NSSL, as well as those of the matrix, were obtained with nanoindentation technology. The reverse analysis of FEM was conducted with MARC software, and the process of nanoindentation on the NSSL and the matrix was simulated. The plastic mechanical properties of NSSL can be derived from the simulation by comparing the results of the simulation and of actual nanoindentation.

  8. Carbohydrate composition of rat intestine surface mucus layer after ceftriaxone treatment.

    Science.gov (United States)

    Holota, Yu V; Olefir, Ya A; Dovbynchuk, T V; Tolstanova, G M

    2016-01-01

    The epidemiological studies have shown that antibiotic treatment increases the susceptibility to inflammatory bowel disease development. The disturbance of mucus layer integrity might be one of the possible mechanisms. The aim of the present study was to investigate the effect of antibiotic ceftriaxone treatment on glycoproteins level and its carbohydrate composition in surface mucus layer of rat intestine. The study was done on male Wistar rats (140-160 g). Ceftriaxone (300 mg/kg, i.m.) was administered once a day for 14 days. The surface mucus from terminal ileum and colon were collected on the 15th, 29th and 72nd days of the experiment. Total level of mucus glycoproteins, hexoses, hexosamines, fucose and sialic acids were measured. Ceftriaxone administration did not affect the levels of glycoproteins in rat ileum. In the colon, the levels of glycoprotein were 1.3-fold decreased (Р ceftriaxone administration induces the long-term changes in the levels of glycoproteins and carbohydrates composition in the rat colon surface mucus. This could potentially explain the susceptibility to inflammatory bowel disea­ses development.

  9. Experimental Investigation of Compliant Wall Surface Deformation in Turbulent Boundary Layer

    Science.gov (United States)

    Wang, Jin; Agarwal, Karuna; Katz, Joseph

    2017-11-01

    On-going research integrates Tomographic PIV (TPIV) with Mach-Zehnder Interferometry (MZI) to measure the correlations between deformation of a compliant wall and a turbulent channel flow or a boundary layer. Aiming to extend the scope to two-way coupling, in the present experiment the wall properties have been designed, based on a theoretical analysis, to increase the amplitude of deformation to several μm, achieving the same order of magnitude as the boundary layer wall unit (5-10 μm). It requires higher speeds and a softer surface that has a Young's modulus of 0.1MPa (vs. 1Mpa before), as well as proper thickness (5 mm) that maximize the wall response to excitation at scales that fall within the temporal and spatial resolution of the instruments. The experiments are performed in a water tunnel extension to the JHU refractive index matched facility. The transparent compliant surface is made of PDMS molded on the tunnel window, and measurements are performed at friction velocity Reynolds numbers in the 1000-7000 range. MZI measures the 2D surface deformation as several magnifications. The time-resolved 3D pressure distribution is determined by calculating to spatial distribution of material acceleration from the TPIV data and integrating it using a GPU-based, parallel-line, omni-directional integration method. ONR.

  10. Arab ESL Secondary School Students’ Spelling Errors

    Directory of Open Access Journals (Sweden)

    Bandar Mohammad Saeed Al-Sobhi

    2017-07-01

    Full Text Available English spelling has always been described by many language researchers and teachers as a daunting task especially for learners whose first language is not English. Accordingly, Arab ESL learners commit serious errors when they spell out English words. The primary objective of this paper is to determine the types as well as the causes of spelling errors made by Arab ESL secondary school students. In order to collect the data, a fifty-word standardised spelling test was administered to seventy Arab student participants. The students’ types of spelling errors were detected, analysed and then categorised according to Cook’s (1999 classification of errors namely substitution, omission, insertion and transposition. In total, 2,873 spelling errors of various categories were identified. The study findings revealed that errors of substitution constituted the highest percentage of the students’ type of errors. In addition, the study indicated that the main causes of the students’ spelling errors were possibly attributed to the anomalous nature of the English spelling system, the Arab students’ lack of awareness of English spelling rules as well as L1 interference. Despite being conducted in an ESL context, the study was almost consistent with the findings indicated by other studies which were carried out in many Arabic EFL context. The findings suggest that spelling instruction should be emphasised while teaching English and should also be integrated with the skills and subskills of reading, writing, pronunciation and vocabulary in order to develop the students’ spelling accuracy.

  11. Using IR-measured soil surface temperatures to estimate hydraulic properties of the top soil layer

    Science.gov (United States)

    Steenpass, Christian; Vanderborght, Jan; Herbst, Michael; Simunek, Jirka; Vereecken, Harry

    2010-05-01

    The temporal and spatial development of soil surface temperatures (SST) depends on water availability in the near-surface soil layer. Since the soil loses latent heat during evaporation and water available for evaporation depends on soil hydraulic properties (SHP), the temporal variability of SST should contain information about the near-surface SHP. This study was conducted to investigate the information content of soil surface temperatures for estimation of soil hydraulic properties and their uncertainties, and to determine the effect of soil tillage on near-surface SHP. A hydrological model (HYDRUS-1D) coupled with a global optimizer (DREAM) was used to inversely estimate the van Genuchten-Mualem parameters of SHP from infra-red measured SST and TDR-measured water contents. The general applicability of this approach was tested using synthetic data. The same approach was then applied to a real data set, which was collected during September 2008 in Selhausen, Germany. The synthetic data set was generated using HYDRUS-1D for the same initial and boundary conditions and measurement protocol as the real data set. Using synthetic and real data it was found that although estimated SHP are sensitive to SST, their estimates are relatively uncertain when only information about SST is used. These uncertainties can be reduced by additionally considering also measured soil water contents. A comparison of SHP determined in the laboratory on undisturbed soil samples with those estimated from SST and TDR data measured in a harrowed soil showed similar results for the deeper undisturbed soil and large differences for the harrowed part of the soil profile. This shows the important effect of soil tillage on soil hydraulic properties. Application of the method in the field to characterize the hydraulic properties of the upper soil layer may reduce the amount of needed in-soil measurements and therefore allows larger scale observations.

  12. Surface Modification of the Ti6Al4V Alloy with Silicon Carbonitride Layer Deposited by PACVD Method

    Science.gov (United States)

    Jonas, Stanisława; Konefał-Góral, Jadwiga; Małek, Anna; Kluska, Stanisława; Grzesik, Zbigniew

    2014-09-01

    Four different layers of various silicon, carbon and nitrogen contents on the Ti6Al4V alloy and (001)Si wafers have been deposited by means of Plasma Assisted Chemical Vapor Deposition (PACVD) method. The layers were obtained from reactive gas mixture containing SiH4, CH4, NH3 and Ar. After deposition the structure and chemical composition of modified surfaces have been analyzed with use of SEM/EDS technique. Based on these results and thermodynamic calculations, the diffusion coefficients, D, for nitrogen and carbon in alloy were discussed. Scratch test shown that silicon carbonitride layers have good adhesion to metal surface. In order to determine atomic structure of obtained layers, FTIR spectra for layer-(001)Si and layer-Ti6Al4V were registered.

  13. Patterns of canopy and surface layer consumption in a boreal forest fire from repeat airborne lidar

    Science.gov (United States)

    Alonzo, Michael; Morton, Douglas C.; Cook, Bruce D.; Andersen, Hans-Erik; Babcock, Chad; Pattison, Robert

    2017-05-01

    Fire in the boreal region is the dominant agent of forest disturbance with direct impacts on ecosystem structure, carbon cycling, and global climate. Global and biome-scale impacts are mediated by burn severity, measured as loss of forest canopy and consumption of the soil organic layer. To date, knowledge of the spatial variability in burn severity has been limited by sparse field sampling and moderate resolution satellite data. Here, we used pre- and post-fire airborne lidar data to directly estimate changes in canopy vertical structure and surface elevation for a 2005 boreal forest fire on Alaska’s Kenai Peninsula. We found that both canopy and surface losses were strongly linked to pre-fire species composition and exhibited important fine-scale spatial variability at sub-30 m resolution. The fractional reduction in canopy volume ranged from 0.61 in lowland black spruce stands to 0.27 in mixed white spruce and broadleaf forest. Residual structure largely reflects standing dead trees, highlighting the influence of pre-fire forest structure on delayed carbon losses from aboveground biomass, post-fire albedo, and variability in understory light environments. Median loss of surface elevation was highest in lowland black spruce stands (0.18 m) but much lower in mixed stands (0.02 m), consistent with differences in pre-fire organic layer accumulation. Spatially continuous depth-of-burn estimates from repeat lidar measurements provide novel information to constrain carbon emissions from the surface organic layer and may inform related research on post-fire successional trajectories. Spectral measures of burn severity from Landsat were correlated with canopy (r = 0.76) and surface (r = -0.71) removal in black spruce stands but captured less of the spatial variability in fire effects for mixed stands (canopy r = 0.56, surface r = -0.26), underscoring the difficulty in capturing fire effects in heterogeneous boreal forest landscapes using proxy measures of burn

  14. Mechanical characterisation of surface layers by x-ray diffraction -application to tribology

    International Nuclear Information System (INIS)

    Farrahi, G.H.

    1996-01-01

    The results presented in this paper show that X-ray diffraction can be employed for the characterisation of surface layer damage through residual stresses and work hardening by some tribological actions such as fretting and dry sliding. X-ray diffraction technique can also be employed for a rapid and non-destructive measurement of hardness of hardened steel. The diffraction profile analysis can offer a good indication about the materials characteristics and the microstructural evolution caused by heat treatment or by mechanical loading

  15. Fatigue crack growth and fracture mechanics analysis of a working roll surface layer material

    Directory of Open Access Journals (Sweden)

    M. Drobne

    2014-10-01

    Full Text Available Fatigue crack growth and fracture mechanics analysis of a working roll surface layer material is presented in this paper. The research is done on a hot strip mill working roll where High Chromium Steel is used for roll’s shell material. To obtain corresponding parameters, a rectangular single edge notched bend specimens – SENB, according to standard BS 7448, were used. The fatigue crack growth analysis was done on a resonant testing machine with use of special crack gauges, while for fracture mechanics parameters the electro–mechanical testing machine was used.

  16. Residual Stress Examination In Surface Layers Turned By Auto-Rotary Tool

    Science.gov (United States)

    Struharňanský, Jozef; Stančeková, Dana; Martikáň, Anton; Varga, Daniel; Kuždál, Viktor; Rákoci, Jozef

    2015-12-01

    In this article, unconventional kinematics of turning is examined with the aim on influence of cutting parameters on surface layers residual stress. The auto-rotary cutting tool prototype for turning was developed, designed and constructed at the University of Zilina. The tool is made of high speed steel. Residual stress examination of material 100Cr6 was performed by non-destructive measuring method of X-ray diffraction. This method is able to determine normal and shear stress conditions without damaging the examined sample.

  17. Tests of Parameterized Langmuir Circulation Mixing in the Oceans Surface Mixed Layer II

    Science.gov (United States)

    2017-08-11

    zero in deep mixed layers below the influence of the surface waves. When the SDC is zero, the GV and GS functions ((29) and (30)) will be zero, and...current and do not include the SDC. With the inclusion of the SDC in the Coriolis term in the momentum equations, the net transport of u is not zero, but...balances the net transport of the SDC us, so that the combined net downwind transport of the Eulerian current plus the SDC is zero. Hence, since the

  18. Diagnosis of the surface layer damage in a 1960s reinforced concrete building

    Directory of Open Access Journals (Sweden)

    S.L. Pagliolico

    2014-01-01

    Full Text Available This work aimed to determine the degradation causes of the Palace of Public Works located in S. Giovanni square in Turin (Piedmont, Italy. The samples collected from the surface layer were characterized by means of scanning electron microscopy (SEM, X-ray diffraction (XRD, thermogravimetric coupled with differential thermal analysis (TG-DTA, mercury intrusion porosimetry measurements (MIP and phenolphthalein test. Metallographic and elemental analyses were also carried out on the steel reinforcing bars. An exhaustive picture of the main causes of deterioration was drawn in order to design the intervention of rehabilitation.

  19. Controlled Dissolution of Surface Layers for Elemental Analysis by Inductively Coupled Plasma-Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lorge, Susan Elizabeth [Iowa State Univ., Ames, IA (United States)

    2007-01-01

    Determining the composition of thin layers is increasingly important for a variety of industrial materials such as adhesives, coatings and microelectronics. Secondary ion mass spectrometry (SIMS), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), glow discharge optical emission spectroscopy (GDOES), glow discharge mass spectrometry (GDMS), and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) are some of the techniques that are currently employed for the direct analysis of the sample surface. Although these techniques do not suffer from the contamination problems that often plague sample dissolution studies, they do require matrix matched standards for quantification. Often, these standards are not readily available. Despite the costs of clean hoods, Teflon pipette tips and bottles, and pure acids, partial sample dissolution is the primary method used in the semiconductor industry to quantify surface impurities. Specifically, vapor phase decomposition (VPD) coupled to ICP-MS or total reflection x-ray fluorescence (TXRF) provides elemental information from the top most surface layers at detection sensitivities in the 107-1010atoms/cm2 range. The ability to quantify with standard solutions is a main advantage of these techniques. Li and Houk applied a VPD-like technique to steel. The signal ratio of trace element to matrix element was used for quantification. Although controlled dissolution concentrations determined for some of the dissolved elements agreed with the certified values, concentrations determined for refractory elements (Ti, Nb and Ta) were too low. LA-ICP-MS and scanning electron microscopy (SEM) measurements indicated that carbide grains distributed throughout the matrix were high in these refractory elements. These elements dissolved at a slower rate than the matrix element, Fe. If the analyte element is not removed at a rate similar to the matrix element a true

  20. Surface Modification of Electrospun PVDF/PAN Nanofibrous Layers by Low Vacuum Plasma Treatment

    Directory of Open Access Journals (Sweden)

    Fatma Yalcinkaya

    2016-01-01

    Full Text Available Nanofibres are very promising for water remediation due to their high porosity and small pore size. Mechanical properties of nanofibres restrict the application of pressure needed water treatments. Various PAN, PVDF, and PVDF/PAN nanofibre layers were produced, and mechanical properties were improved via a lamination process. Low vacuum plasma treatment was applied for the surface modification of nanofibres. Atmospheric air was used to improve hydrophilicity while sulphur hexafluoride gas was used to improve hydrophobicity of membranes. Hydrophilic membranes showed higher affinity to attach plasma particles compared to hydrophobic membranes.

  1. Growth and behavior of chondrocytes on nano engineered surfaces and construction of micropatterned co-culture platforms using layer-by-layer platforms using layer-by-layer assembly lift-off method

    Science.gov (United States)

    Shaik, Jameel

    Several approaches such as self-assembled monolayers and layer-by-layer assembled multilayer films are being used as tools to study the interactions of cells with biomaterials in vitro. In this study, the layer-by-layer assembly approach was used to create monolayer, bilayer, trilayer, five, ten and twenty-bilayer beds of eleven different biomaterials. The various biomaterials used were poly(styrene-sulfonate), fibronectin, poly-L-lysine, poly-D-lysine, laminin, bovine serum albumin, chondroitin sulfate, poly(ethyleneimine), polyethylene glycol amine, collagen and poly(dimethyldiallyl-ammonium chloride) with unmodified tissue-culture polystyrene as standard control. Three different cell lines---primary bovine articular chondrocytes, and two secondary cell lines, human chondrosarcoma cells and canine chondrocytes were used in these studies. Chondrocyte morphology and attachment, viability, proliferation, and functionality were determined using bright field microscopy, the Live/Dead viability assay, MTT assay, and immunocytochemistry, respectively. Atomic force microscopy of the nanofilms indicated an increase in surface roughness with increasing number of layers. The most important observations from the studies on primary bovine articular chondrocytes were that these cells exhibited increasing viability and cell metabolic activity with increasing number of bilayers. The increase in viability was more pronounced than the increase in cell metabolic activity. Also, bovine chondrocytes on bilayers of poly(dimethyldiallyl-ammonium chloride, poly-L-lysine, poly(styrene-sulfonate), and bovine serum albumin were substantially bigger in size and well-attached when compared to the cells grown on monolayer and trilayers. Lactate dehydrogenase assay performed on chondrosarcoma cells grown on 5- and 10-bilayer multilayer beds indicated that the 10-bilayer beds had reduced cytotoxicity compared to the 5-bilayer beds. MTT assay performed on canine chondrocytes grown on 5-, 10

  2. Influence of surface layer removal of shade guide tabs on the measured color by spectrophotometer and spectroradiometer.

    Science.gov (United States)

    Kim, Jin-Cheol; Yu, Bin; Lee, Yong-Keun

    2008-12-01

    To determine the changes in color parameters of Vitapan 3D-Master shade guide tabs by a spectrophotometer (SP) or a spectroradiometer (SR), and by the removal of the surface layer of the tabs that was performed to make a flat measuring surface for the SP color measurement. Color of the shade tabs was measured before and after removing the surface layer of the tabs using SP and SR. Correlations between the color parameters between the original (OR) and the surface layer removed (RM) tabs and between the SP and the SR measurements were determined (alpha=0.05). Based on SP, the lightness, chroma, CIE a* and b* values measured after the surface layer removal were higher than those of the original tabs except a few cases. Based on SR, the chroma and CIE a* and b* values measured after surface layer removal were higher than those of the original tabs except a few cases; however, in case of the lightness, the changes varied by the shade designation. Type of instrument influenced the changes in color parameters based on paired t-test (pspectrophotometer or a spectroradiometer, measurement protocols should be specified because color difference by the surface layer removal and the instrument was high.

  3. Contact-free calibration of an asymmetric multi-layer interferometer for the surface force balance

    Science.gov (United States)

    Balabajew, Marco; van Engers, Christian D.; Perkin, Susan

    2017-12-01

    The Surface Force Balance (SFB, also known as Surface Force Apparatus, SFA) has provided important insights into many phenomena within the field of colloid and interface science. The technique relies on using white light interferometry to measure the distance between surfaces with sub-nanometer resolution. Up until now, the determination of the distance between the surfaces required a so-called "contact calibration," an invasive procedure during which the surfaces are brought into mechanical contact. This requirement for a contact calibration limits the range of experimental systems that can be investigated with SFB, for example, it precludes experiments with substrates that would be irreversibly modified or damaged by mechanical contact. Here we present a non-invasive method to measure absolute distances without performing a contact calibration. The method can be used for both "symmetric" and "asymmetric" systems. We foresee many applications for this general approach including, most immediately, experiments using single layer graphene electrodes in the SFB which may be damaged when brought into mechanical contact.

  4. Influence of surface rectangular defect winding layer on burst pressure of CNG-II composite cylinder

    Science.gov (United States)

    You, H. X.; Peng, L.; Zhao, C.; Ma, K.; Zhang, S.

    2018-01-01

    To study the influence of composite materials’ surface defect on the burst pressure of CNG-II composite cylinder, the surface defect was simplified as a rectangular slot of certain size on the basis of actually investigating the shape of cylinder’s surface defect. A CNG-II composite cylinder with a rectangular slot defect (2mm in depth) was used for burst test, and the numerical simulation software ANSYS was used to calculate its burst pressure. Through comparison between the burst pressure in the test and the numerical analysis result, the correctness of the numerical analysis method was verified. On this basis, the numerical analysis method was conducted for composite cylinders with surface defect in other depth. The result showed that surface defect in the form of rectangular slot had no significant effect on the liner stress of composite cylinder. Instead, it had a great influence on the stress of fiber-wrapped layer. The burst pressure of the composite cylinder decreased as the defect depth increasing. The hoop stress at the bottom of the defect in the shape of rectangular slot exceeded the maximum of the composite materials’ tensile strength, which could result in the burst pressure of composite cylinders decreasing.

  5. Silicon surface passivation using thin HfO2 films by atomic layer deposition

    International Nuclear Information System (INIS)

    Gope, Jhuma; Vandana; Batra, Neha; Panigrahi, Jagannath; Singh, Rajbir; Maurya, K.K.; Srivastava, Ritu; Singh, P.K.

    2015-01-01

    Graphical abstract: - Highlights: • HfO 2 films using thermal ALD are studied for silicon surface passivation. • As-deposited thin film (∼8 nm) shows better passivation with surface recombination velocity (SRV) <100 cm/s. • Annealing improves passivation quality with SRV ∼20 cm/s for ∼8 nm film. - Abstract: Hafnium oxide (HfO 2 ) is a potential material for equivalent oxide thickness (EOT) scaling in microelectronics; however, its surface passivation properties particularly on silicon are not well explored. This paper reports investigation on passivation properties of thermally deposited thin HfO 2 films by atomic layer deposition system (ALD) on silicon surface. As-deposited pristine film (∼8 nm) shows better passivation with <100 cm/s surface recombination velocity (SRV) vis-à-vis thicker films. Further improvement in passivation quality is achieved with annealing at 400 °C for 10 min where the SRV reduces to ∼20 cm/s. Conductance measurements show that the interface defect density (D it ) increases with film thickness whereas its value decreases after annealing. XRR data corroborate with the observations made by FTIR and SRV data.

  6. Characterization of surface electrochemical reactions used in electrochemical atomic layer epitaxy and digital etching

    Science.gov (United States)

    Sorenson, Thomas Allen

    Surface analytical techniques have been used to characterize electrochemical reactions to be used in semiconductor processing technologies. Studies have been performed using UHV-EC methodology to determine conditions for the surface limited dissolution of CdTe(100). Electrochemical conditions were identified which resulted in the reduction of the top layer of tellurium atoms, leaving behind a cadmium enriched surface. Attempts to find an electrochemical potential for the oxidative dissolution of the cadmium surface were complicated by the simultaneous oxidation of the compound CdTe. In situ scanning tunneling microscopy has also been used to characterize the formation of tellurium atomic layers formed on Au(111) and Au(100) by underpotential deposition. On Au(100), the following sequence of surface structures was observed prior to bulk electrodeposition: a p(2x2), a (2x✓10), a (2x4), and a (✓2x✓5). The transitions between these structures was observed by STM and mechanisms for the phase transitions are presented. The results are correlated to UHV-EC studies of tellurium UPD on Au(100). On Au(111), the following sequence of structures was observeḑ: a (✓3 x✓3), a (✓7x✓13), and a (3x3). The (✓3x✓3) was shown to exist with a network of domain walls, forming long range triangular and diamond shaped superstructures. Conversion of the (✓3x✓3) to higher coverage structure resulted in roughening of the underlying Au surface and a mechanism is hypothesized to explain this transition. The STM results are also correlated to low energy electron diffraction (LEED) results obtained by UHV-EC studies. The surface structures formed by reductive UPD of the chalcogenide elements and Se on both Au(100) and Au(111) are compared. Both elements initially resulted in structures consisting of isolated atoms separated by distances close to the reported van der Waals diameter. Higher coverage structures resulted in interatomic chalcogenide bonding and the structures

  7. Teachers' Assessment of ESL Students in Mainstream Classes: Challenges, Strategies, and Decision-Making

    Science.gov (United States)

    Cheng, Liying; Milnes, Terry

    2008-01-01

    Given the increasing numbers of ESL students in Canadian classrooms, this study investigated how teachers of mainstream classes assess the written work of ESL students and whether they use different assessment strategies for ESL versus non-ESL students. Interviews were conducted with seven mainstream teachers from a private high school in Ontario.…

  8. Robust numerical methods for boundary-layer equations for a model problem of flow over a symmetric curved surface

    NARCIS (Netherlands)

    A.R. Ansari; B. Hossain; B. Koren (Barry); G.I. Shishkin (Gregori)

    2007-01-01

    textabstractWe investigate the model problem of flow of a viscous incompressible fluid past a symmetric curved surface when the flow is parallel to its axis. This problem is known to exhibit boundary layers. Also the problem does not have solutions in closed form, it is modelled by boundary-layer

  9. Investigating the Effect of Growth Phase on the Surface-Layer Associated Proteome of Lactobacillus acidophilus Using Quantitative Proteomics

    Directory of Open Access Journals (Sweden)

    Courtney Klotz

    2017-11-01

    Full Text Available Bacterial surface-layers (S-layers are semi-porous crystalline arrays that self-assemble to form the outermost layer of some cell envelopes. S-layers have been shown to act as scaffolding structures for the display of auxiliary proteins externally. These S-layer associated proteins have recently gained attention in probiotics due to their direct physical contact with the intestinal mucosa and potential role in cell proliferation, adhesion, and immunomodulation. A number of studies have attempted to catalog the S-layer associated proteome of Lactobacillus acidophilus NCFM under a single condition. However, due to the versatility of the cell surface, we chose to employ a multiplexing-based approach with the intention of accurately contrasting multiple conditions. In this study, a previously described lithium chloride isolation protocol was used to release proteins bound to the L. acidophilus S-layer during logarithmic and early stationary growth phases. Protein quantification values were obtained via TMT (tandem mass tag labeling combined with a triple-stage mass spectrometry (MS3 method. Results showed significant growth stage-dependent alterations to the surface-associated proteome while simultaneously highlighting the sensitivity and reproducibility of the technology. Thus, this study establishes a framework for quantifying condition-dependent changes to cell surface proteins that can easily be applied to other S-layer forming bacteria.

  10. Electromagnetic fields due to a horizontal electric dipole antenna laid on the surface of a two-layer medium

    Science.gov (United States)

    Tsang, L.; Kong, J. A.

    1974-01-01

    With applications to geophysical subsurface probings, electromagnetic fields due to a horizontal electric dipole laid on the surface of a two-layer medium are solved by a combination of analytic and numerical methods. Interference patterns are calculated for various layer thickness. The results are interpreted in terms of normal modes, and the accuracies of the methods are discussed.

  11. Rendering of surface-geometries at job-generation level for camouflaging the layered nature of Additively Manufactured parts

    DEFF Research Database (Denmark)

    Pedersen, D. B.; Hansen, H. N.; Nielsen, J. S.

    2014-01-01

    The layered nature of Additive Manufactured parts, specifically those given from the Fused Deposition Modelling (FDM) process, exhibit a distinct surface definition. The origin of this is from the 2.5D deposition scheme, which leaves the seam between the individual layers clearly visible.[1...

  12. Surfactant-induced layered growth in homoepitaxy of Fe on Fe(100)-c(2 x 2)O reconstruction surface

    International Nuclear Information System (INIS)

    Kamiko, Masao; Mizuno, Hiroyuki; Chihaya, Hiroaki; Xu, Junhua; Kojima, Isao; Yamamoto, Ryoichi

    2007-01-01

    In this study, the effects of several surfactants (Pb, Bi, and Ag) on the homoepitaxial growth of Fe(100) were studied and compared. The reflection high-energy electron diffraction measurements clearly reveal that these surfactants enhance the layer-by-layer growth of Fe on an Fe(100)-c(2 x 2)O reconstruction surface. The dependence of growth on the surfactant layer thickness suggests that there exists a suitable amount of surfactant layer that induces a smoother layer-by-layer growth. Comparisons between the atomic force microscopy images reveal that the root-mean-square surface roughness of Fe films mediated by Pb and Bi surfactants are considerably smaller than those of the films mediated by Ag surfactant. The Auger electron spectra show that Pb and Bi segregate at the top of the surface. It has been concluded that Pb and Bi are effective surfactants for enhancing layer-by-layer growth in Fe homoepitaxy. Ag has the same effect, but it is less efficient due to the weak surface segregation of Ag

  13. A fracture mechanics assessment of surface cracks existing in protective layers of multi-layer composite pipes

    Czech Academy of Sciences Publication Activity Database

    Hutař, Pavel; Náhlík, Luboš; Šestáková, Lucie; Ševčík, Martin; Knésl, Zdeněk; Nezbedová, E.

    2010-01-01

    Roč. 92, č. 5 (2010), s. 1120-1125 ISSN 0263-8223 R&D Projects: GA ČR GA106/09/0279 Institutional research plan: CEZ:AV0Z20410507 Keywords : Protective layers * Multi-layer pipes damage * Fracture mechanics * Bi-material interface * Generalized stress intensity factor Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 2.028, year: 2010

  14. Chlorophyll modulation of sea surface temperature in the Arabian Sea in a mixed-layer isopycnal general circulation model

    Digital Repository Service at National Institute of Oceanography (India)

    Nakamoto, S.; PrasannaKumar, S.; Muneyama, K.; Frouin, R.

    Remotely sensed chlorophyll pigment concentrations from the Coastal Zone Color Scanner (CZCS) are used to estimate biological heating rate and investigate the biological modulation of the sea surface temperature (SST) in a bulk mixed layer model...

  15. X-ray diffraction analysis of rust layer on a weathering steel bridge with surface treatment using synchrotron radiation

    International Nuclear Information System (INIS)

    Yamashita, Masato; Hara, Shuichi; Kamimura, Takayuki; Miyuki, Hideaki; Sato, Masugu

    2007-01-01

    We have examined the structure of rust layer formed on a weathering steel bridge, to which the surface treatment, employing the effect of Cr 2 (SO 4 ) 3 sophisticatedly designed to form the protective goethite (α-FeOOH) rust layer which contains a certain amount of Cr, Cr-goethite, was applied in 1996, using X-ray diffraction at SPring-8 synchrotron radiation facility. It was shown that the formation of α-FeOOH was promoted and/or crystal growth of γ-FeOOH was suppressed by the surface treatment. The increase in the protective ability index (PAI) of the rust layer indicates that the protective goethite was predominantly formed under the effect of the surface treatment. In conclusion, it can be said that the surface treatment worked well to promote the formation of the protective goethite rust layer on the weathering steel bridge during the 10-year exposure. (author)

  16. Viscoelastic modeling of highly hydrated laminin layers at homogeneous and nanostructured surfaces: quantification of protein layer properties using QCM-D and SPR.

    Science.gov (United States)

    Malmström, Jenny; Agheli, Hossein; Kingshott, Peter; Sutherland, Duncan S

    2007-09-11

    The adsorption of proteins at material surfaces is important in applications such as biomaterials, drug delivery, and diagnostics. The interaction of cells with artificial surfaces is mediated through adsorbed proteins, where the type of protein, amount, orientation, and conformation are of consequence for the cell response. Laminin, an important cell adhesive protein that is central in developmental biology, is studied by a combination of quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance (SPR) to characterize the adsorption of laminin on surfaces of different surface chemistries. The combination of these two techniques allows for the determination of the thickness and effective density of the protein layer as well as the adsorbed mass and viscoelastic properties. We also evaluate the capacity of QCM-D to be used as a quantitative technique on a nanostructured surface, where protein is adsorbed specifically in a nanopattern exploiting PLL-g-PEG as a protein-resistant background. We show that laminin forms a highly hydrated protein layer with different characteristics depending on the underlying substrate. Using a combination of QCM-D and atomic force microscopy (AFM) data from nanostructured surfaces, we model laminin and antibody binding to nanometer-scale patches. A higher amount of laminin was found to adsorb in a thicker layer of a lower effective density in nanopatches compared to equivalent homogeneous surfaces. These results suggest that modeling of QCM-D data of soft viscoelastic layers arranged in nanopatterns may be applied where an independent measure of the "dry" mass is known.

  17. A revised surface age for the North Polar Layered Deposits of Mars

    Science.gov (United States)

    Landis, Margaret E.; Byrne, Shane; Daubar, Ingrid J.; Herkenhoff, Kenneth E.; Dundas, Colin M.

    2016-01-01

    The North Polar Layered Deposits (NPLD) of Mars contain a complex stratigraphy that has been suggested to retain a record of past eccentricity- and obliquity-forced climate changes. The surface accumulation rate in the current climate can be constrained by the crater retention age. We scale NPLD crater diameters to account for icy target strength and compare surface age using a new production function for recent small impacts on Mars to the previously used model of Hartmann (2005). Our results indicate that ice is accumulating in these craters several times faster than previously thought, with a 100 m diameter crater being completely infilled within centuries. Craters appear to have a diameter-dependent lifetime, but the data also permit a complete resurfacing of the NPLD at ~1.5 ka.

  18. Morphological features of the copper surface layer under sliding with high density electric current

    Energy Technology Data Exchange (ETDEWEB)

    Fadin, V. V., E-mail: fvv@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Aleutdinova, M. I., E-mail: aleut@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Seversk Technological Institute, Branch of State Autonomous Educational Institution of Higher Professional Education “National Research Nuclear University “MEPhI”, Seversk, 636036 (Russian Federation); Rubtsov, V. Ye., E-mail: rvy@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Aleutdinova, V. A., E-mail: valery-aleut@yandex.ru [National Research St. Petersburg State Polytechnical University, St. Petersburg, 195251 (Russian Federation)

    2015-10-27

    Conductivity and wear intensity of copper under the influence of dry friction and electric current with contact density higher 100 A/cm{sup 2} are presented. It is shown that an increase in hardness and heat outflow from a friction zone leads to the reduction of wear intensity and current contact density increase corresponding to the beginning of catastrophic wear. Structural changes, such as the formation of FeO oxide and α-Fe particles in the copper surface layer, have also been found. It is observed that a worn surface is deformed according to a viscous liquid mechanism. Such singularity is explained in terms of appearance of high-excited atomic states in deforming micro-volumes near contact spots that lead to easy stress relaxation by local plastic shears in the vicinity of stress concentrators. In common this effect allows to achieve high wear resistance.

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

    International Nuclear Information System (INIS)

    Sudjatmoko; Subki, M. Iyos R.

    2000-01-01

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

  20. Russian Immigrants in the ESL Classroom. Success, Motivation, and Acculturation.

    Science.gov (United States)

    Berman, Michael

    1998-01-01

    Discusses the success, motivation, and acculturation of Russian immigrants in English-as-a-Second-Language (ESL) classrooms, explaining why they are motivated and well-prepared, discussing variations in their previous English education, examining the effects of cultural differences, and noting other problems that they may face in ESL classrooms…

  1. Ethical Issues in Addressing Inequity in/through ESL Research

    Science.gov (United States)

    Lee, Ena

    2011-01-01

    This article outlines a researcher's struggles with conducting "ethical" research when her case study reveals racializations faced by a minority teacher in a Canadian ESL program. How might becoming privy to research participants' experiences of inequity in ESL education complicate the notion of research ethics when "doing the right…

  2. Translating Information Literacy: Online Library Support for ESL Students

    Science.gov (United States)

    Lombard, Emmett

    2016-01-01

    This article describes information literacy struggles of ESL college students within the context of four information literacy components: Identify, Locate, Evaluate, Use. Experiences from an online freshman composition course are used to illustrate these struggles, along with techniques academic librarians use to help ESL students from a distance.

  3. Balancing Act: Addressing Culture and Gender in ESL Classrooms

    Science.gov (United States)

    Johnson, Michelle A.; Chang, Debbie

    2012-01-01

    ESL educators find themselves teaching a diverse group of students in today's classroom. This study investigated how ESL instructors address diversity in their teaching. The literature review revealed research on the experiences of teachers using culturally responsive teaching strategies. Using qualitative research methods, this study explores the…

  4. Losing Strangeness: Using Culture to Mediate ESL Teaching

    Science.gov (United States)

    Rowsell, Jennifer; Sztainbok, Vannina; Blaney, Judy

    2007-01-01

    This paper explores ways of using culture and cultural practices as an informing principle in ESL teaching. To research culture and ESL teaching, we conducted focus groups with teachers in an urban ethnically diverse school in Toronto, Canada and their student teachers during their month-long practice in the school as a part of a Bachelor of…

  5. Lexical Borrowings in the ESL Classrooms in Malaysia

    Science.gov (United States)

    Thirusanku, Jantmary; Yunus, Melor Md

    2013-01-01

    This paper attempts to show the use of lexical borrowings in ten teaching materials used by the English as Second Language (ESL) teachers in the ESL classrooms in the National Secondary Schools in the Klang district in Selangor, Malaysia. It also discusses the general and pedagogical implications involved in using lexical borrowings. This paper…

  6. Accent, Identity, and a Fear of Loss? ESL Students' Perspectives

    Science.gov (United States)

    McCrocklin, Shannon; Link, Stephanie

    2016-01-01

    Because many theorists propose a connection between accent and identity, some theorists have justifiably been concerned about the ethical ramifications of L2 pronunciation teaching. However, English-as-a-second-language (ESL) students often state a desire to sound like native speakers. With little research into ESL students' perceptions of links…

  7. The Use of Progressives among Malaysian ESL Learners

    Science.gov (United States)

    Narinasamy, Ilhamanggai; Mukundan, Jayakaran; Nimehchisalem, Vahid

    2013-01-01

    Studies on ESL/EFL learners' use of the progressives reveal that it is one of the grammatical aspects most problematic to them. This paper presents the results of a study on the use of progressives among Year 5, Form 1 and Form 4 Malaysian ESL learners' compositions using the English of Malaysian School Students (EMAS) corpus. The purpose of this…

  8. Complex Text in ESL Grammar Textbooks: Barriers or Gateways?

    Science.gov (United States)

    Lesikin, Joan

    2000-01-01

    Suggests that English-as-a-Second-Language (ESL) teachers assess prospective textbooks by comparing real-life user's actual knowledge of the author's assumed student knowledge. Through examination of charts and page excerpts of two ESL grammar textbooks, demonstrates that access to the pedagogical knowledge demands sophisticated formal knowledge,…

  9. Flipped ESL Teacher Professional Development: Embracing Change to Remain Relevant

    Science.gov (United States)

    Razak, Rafiza Abdul; Kaur, Dalwinder; Halili, Siti Hajar; Ramlan, Zahri

    2016-01-01

    Many traditional professional development programs that are initiated to equip ESL teachers with knowledge and skills have been futile for numerous reasons. This paper addresses a gap in the recent research of ESL teachers' professional development. Literature has revealed many shortcomings of the traditional and online professional development…

  10. Prisoners Teaching ESL: A Learning Community among "Language Partners"

    Science.gov (United States)

    Olinger, Andrea; Bishop, Hugh; Cabrales, Jose; Ginsburg, Rebecca; Mapp, Joseph; Mayorga, Orlando; Nava, Erick; Nunez, Elfego; Rosas, Otilio; Slater, Andre; Sorenson, LuAnn; Sosnowski, Jim; Torres, Agustin

    2012-01-01

    This article features Language Partners, an ESL program offered at the Danville Correctional Center, a medium-security men's prison in central Illinois. The program in which prisoners teach ESL classes, supported by volunteer teacher-trainers, is a learning community with immense and sometimes unforeseen value. The authors discuss reasons for…

  11. The Relationship between Instructor Feedback and ESL Student Anxiety

    Science.gov (United States)

    Di Loreto, Sabrina; McDonough, Kim

    2013-01-01

    This correlational study, conducted in intermediate English as a second language (ESL) high school classes in Quebec, investigated the relationship between instructor feedback and student anxiety. The participants were 53 ESL students in their last year of secondary school who were required to take an integrative-writing exam as part of their…

  12. Training Using Technology in the Adult ESL Classroom

    Science.gov (United States)

    McClanahan, Lorna

    2014-01-01

    In this article I discuss two reasons for the slow adoption of technology as an instructional tool in adult English as a Second Language (ESL) education. I outline recent facts about the relationships between today's adult ESL learners and technology, and then construct a background of theoretical support in favor of integrating technology in…

  13. ESL Learners' Online Research and Comprehension Strategies

    Science.gov (United States)

    Sain, Noridah; Bown, Andy; Fluck, Andrew; Kebble, Paul

    2017-01-01

    In order to enhance second language (L2) acquisition, English as a Second Language (ESL) students are encouraged to exploit the abundant information and opportunities for authentic language use afforded by the Internet. This study investigated the online research and comprehension strategies employed by ESL learners in a public university in…

  14. Rethinking ESL Service Courses for International Graduate Students

    Science.gov (United States)

    Min, Young-Kyung

    2016-01-01

    Drawing on data from a writing program in English as a second language (ESL) at a large university in the midwestern United States, this article addresses the significant gap in programmatic and pedagogical responses for graduate writing support by probing the notion of ESL service courses that approach graduate writing courses as being…

  15. Let's Talk! ESL Students' Needs and Writing Centre Philosophy

    Science.gov (United States)

    Moussu, Lucie

    2013-01-01

    When university/college faculty members believe that ESL students' writing skills are not equivalent to those of native speakers, they frequently send these ESL students to their institution's writing centres (WCs). However, this often results in frustration for WC staff, the students, and faculty members. This article first describes ESL…

  16. The trapping of fly-ash particles in the surface layers of Sphagnum-dominated peat

    International Nuclear Information System (INIS)

    Punning, J.-M.; Alliksaar, T.

    1997-01-01

    The movement of fly-ash particles in a sequence of Sphagnum moss was studied in laboratory experiments and field investigations. Fly ash was obtained from the electrostatic precipitators of the Estonian Thermal Power Plant operating on oil shale. The data obtained in the laboratory show that only 0.8% of particles, placed on the surface of a 6-10 cm thick Sphagnum layer, were washed out with water (700-750 mm) during the 241 days of the experiment. The majority of added particles were fixed in the upper part (90% in 1-3 cm) of the moss layer. A SEM study indicates that sorption is slightly species-dependent due to the micromorphological parameters of the Sphagnum species. The storage of particles by Sphagnum mosses allows the use of natural sequences to study the history of atmospheric pollution. The distribution of particles in the upper part of moss layers in Viru Bog (50 km east of Tallinn, North Estonia) shows good agreement with the known air pollution history in Tallinn. 13 refs., 6 figs., 2 tabs

  17. Local environmental conditions and the stability of protective layers on steel surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, J.P. [Technical Univ. of Denmark, Lyngby (Denmark); Bursik, A.

    1996-12-01

    Local environmental conditions determine whether the protective layers on steel surfaces are stable. With unfavorable local environmental conditions, the protective layers may be subject to damage. Taking the cation conductivity of all plant cycle streams <0.2 {mu}S/cm for granted, an adequate feed-water and - if applicable - boiler water conditioning is required to prevent such damage. Even if the mentioned conditions are met in a bulk, the local environmental conditions may be inadequate. The reasons for this may be the disregarding of interactions among material, design, and chemistry. The paper presents many possible mechanisms of protective layer damage that are directly influenced or exacerbated by plant cycle chemistry. Two items are discussed in more detail: First, the application of all volatile treatment for boiler water conditioning of drum boiler systems operating at low pressures and, second, the chemistry in the transition zone water/steam in the low pressure turbine. The latter is of major interest for the understanding and prevention of corrosion due to high concentration of impurities in the aqueous liquid phases. This is a typical example showing that local environmental conditions may fundamentally differ from the overall bulk chemistry. (au) 19 refs.

  18. A Case Study of Offshore Advection of Boundary Layer Rolls over a Stably Stratified Sea Surface

    Directory of Open Access Journals (Sweden)

    Nina Svensson

    2017-01-01

    Full Text Available Streaky structures of narrow (8-9 km high wind belts have been observed from SAR images above the Baltic Sea during stably stratified conditions with offshore winds from the southern parts of Sweden. Case studies using the WRF model and in situ aircraft observations indicate that the streaks originate from boundary layer rolls generated over the convective air above Swedish mainland, also supported by visual satellite images showing the typical signature cloud streets. The simulations indicate that the rolls are advected and maintained at least 30–80 km off the coast, in agreement with the streaks observed by the SAR images. During evening when the convective conditions over land diminish, the streaky structures over the sea are still seen in the horizontal wind field; however, the vertical component is close to zero. Thus advected feature from a land surface can affect the wind field considerably for long times and over large areas in coastal regions. Although boundary layer rolls are a well-studied feature, no previous study has presented results concerning their persistence during situations with advection to a strongly stratified boundary layer. Such conditions are commonly encountered during spring in coastal regions at high latitudes.

  19. Coherent structures in stratocumulus topped boundary layer: sensitivity to surface fluxes, radiative cooling and vertical stability

    Science.gov (United States)

    Davini, Paolo; D'Andrea, Fabio; Park, Seung-bu; Gentine, Pierre

    2017-04-01

    The representation of stratocumulus clouds in global climate models is still a concern for the climate modelling community. This is due to the low efficacy of current parametrization to simulate the full set of phenomena that governs the stratocumulus topped boundary layer (STBL), but also by the inaccurate knowledge of the sensitivities of the STBL dynamics to external large scale forcing. Here we show that making of a series of high-resolution LES simulations, we are able to detect and track coherent structures such as updrafts, downdrafts and their returning shells (i.e. both ascending and subsiding), together with the entraining air from the inversion layer or the free troposphere in a non-precipitating marine nighttime STBL. This is done with a new classification method based on octant analysis - using vertical velocity and two passive scalars - which defines the structures also in cloud-free regions. We are thus able to quantify the geometrical and thermodynamic characteristics (e.g. areal fraction, temperature, liquid and total water mixing ratio, buoyancy, etc.) of those structures, highlighting the single contributions to the turbulent transport of mass, heat and moisture. It is thus possible to estimate the sensitivity of the turbulent fluxes to the intensity of the cloud-top radiative cooling, to the surface latent and sensible fluxes and to the strength of the vertical stability is explored. Indeed, this analysis lays the foundation for a new parametrization of stratocumulus-topped boundary layer for global climate models.

  20. Improved performance of organic light-emitting diode with vanadium pentoxide layer on the FTO surface

    Science.gov (United States)

    Saikia, D.; Sarma, R.

    2017-06-01

    Vanadium pentoxide layer deposited on the fluorine-doped tin oxide (FTO) anode by vacuum deposition has been investigated in organic light-emitting diode (OLED). With 12 nm optimal thickness of V2O5, the luminance efficiency is increased by 1.66 times compared to the single FTO-based OLED. The improvement of current efficiency implies that there is a better charge injection and better controlling of hole current. To investigate the performance of OLED by the buffer layer, V2O5 films of different thicknesses were deposited on the FTO anode and their J- V and L- V characteristics were studied. Further analysis was carried out by measuring sheet resistance, optical transmittance and surface morphology with the FE-SEM images. This result indicates that the V2O5 (12 nm) buffer layer is a good choice for increasing the efficiency of FTO-based OLED devices within the tunnelling region. Here the maximum value of current efficiency is found to be 2.83 cd / A.

  1. Influence of rigid boundary on the propagation of torsional surface wave in an inhomogeneous layer

    Science.gov (United States)

    Gupta, Shishir; Sultana, Rehena; Kundu, Santimoy

    2015-02-01

    The present work illustrates a theoretical study on the effect of rigid boundary for the propagation of torsional surface wave in an inhomogeneous crustal layer over an inhomogeneous half space. It is believed that the inhomogeneity in the half space arises due to hyperbolic variation in shear modulus and density whereas the layer has linear variation in shear modulus and density. The dispersion equation has been obtained in a closed form by using Whittaker's function, which shows the variation of phase velocity with corresponding wave number. Numerical results show the dispersion equations, which are discussed and presented by means of graphs. Results in some special cases are also compared with existing solutions available from analytical methods, which show a close resemblance. It is also observed that, for a layer over a homogeneous half space, the velocity of torsional waves does not coincide with that of Love waves in the presence of the rigid boundary, whereas it does at the free boundary. Graphical user interface (GUI) software has been developed using MATLAB 7.5 to generalize the effect of various parameter discussed.

  2. The effects of 450 kg surface explosions at the E layer of the ionosphere

    International Nuclear Information System (INIS)

    Fitzgerald, T.J.; Carlos, R.C.

    1992-01-01

    A network of hf ionospheric sounders consisting of two transmitter and two receiver stations was deployed to detect the effects of acoustic waves generated by surface ground motion following an underground nuclear test (UGT) at the Nevada Test Site. The frequency of the transmissions were chosen so that the hf radio waves were totally reflected in the E layer of the ionosphere at an altitude of approximately 100 km. The transmissions were highly stable cw tones at two frequencies separated by 100 kHz so that two altitudes separated by approximately .5 km could be sensed. The network sampled four geographic locations in the ionosphere ranging from almost directly overhead of the UGT out to a horizontal range of 60 km. The ionospheric sounders detected disturbances on all the paths beginning at approximately 325 s after the UGT which persisted for up to 100 s. These disturbances will be described in detail in a later paper. Shortly after the UGT an extended series of ionospheric disturbances were detected which we ascribe to the arrival of acoustic shock waves at the E layer caused by the surface detonation of ordinance with effective yields of 450 kg of high explosive during an unrelated exercise conducted by the U. S. Air Force at a nearby bombing range. The conjunction of these disturbances produced a direct comparison of the effects of UGT's and surface explosions in the ionosphere. In this paper we describe the effects produced by the surface explosions and interpret the disturbance in terms of diffraction induced by electron density changes accompanying the passage of the acoustic waves from the explosions through the reflection altitudes

  3. Retrieving 4-dimensional atmospheric boundary layer structure from surface observations and profiles over a single station

    Energy Technology Data Exchange (ETDEWEB)

    Pu, Zhaoxia [Univ. of Utah, Salt Lake City, UT (United States)

    2015-10-06

    Most routine measurements from climate study facilities, such as the Department of Energy’s ARM SGP site, come from individual sites over a long period of time. While single-station data are very useful for many studies, it is challenging to obtain 3-dimensional spatial structures of atmospheric boundary layers that include prominent signatures of deep convection from these data. The principal objective of this project is to create realistic estimates of high-resolution (~ 1km × 1km horizontal grids) atmospheric boundary layer structure and the characteristics of precipitating convection. These characteristics include updraft and downdraft cumulus mass fluxes and cold pool properties over a region the size of a GCM grid column from analyses that assimilate surface mesonet observations of wind, temperature, and water vapor mixing ratio and available profiling data from single or multiple surface stations. The ultimate goal of the project is to enhance our understanding of the properties of mesoscale convective systems and also to improve their representation in analysis and numerical simulations. During the proposed period (09/15/2011–09/14/2014) and the no-cost extension period (09/15/2014–09/14/2015), significant accomplishments have been achieved relating to the stated goals. Efforts have been extended to various research and applications. Results have been published in professional journals and presented in related science team meetings and conferences. These are summarized in the report.

  4. Variable but persistent coexistence of Prochlorococcus ecotypes along temperature gradients in the ocean's surface mixed layer.

    Science.gov (United States)

    Chandler, Jeremy W; Lin, Yajuan; Gainer, P Jackson; Post, Anton F; Johnson, Zackary I; Zinser, Erik R

    2016-04-01

    The vast majority of the phytoplankton communities in surface mixed layer of the oligotrophic ocean are numerically dominated by one of two ecotypes of Prochlorococcus, eMIT9312 or eMED4. In this study, we surveyed large latitudinal transects in the Atlantic and Pacific Ocean to determine if these ecotypes discretely partition the surface mixed layer niche, or if populations exist as a continuum along key environmental gradients, particularly temperature. Transitions of dominance occurred at approximately 19-21°C, with the eMED4 ecotype dominating the colder, and eMIT9312 ecotype dominating the warmer regions. Within these zones of regional dominance, however, the minority ecotype was not competed to extinction. Rather, a robust log-linear relationship between ecotype ratio and temperature characterized this stabilized coexistence: for every 2.5°C increase in temperature, the eMIT9312:eMED4 ratio increased by an order of magnitude. This relationship was observed in both quantitative polymerase chain reaction and in pyrosequencing assays. Water column stratification also contributed to the ecotype ratio along the basin-scale transects, but to a lesser extent. Finally, instances where the ratio of the eMED4 and eMIT9312 abundances did not correlate well with temperature were identified. Such occurrences are likely due to changes in water temperatures outpacing changes in community structure. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  5. Surface Layers of Zr-18%Nb Alloy Modified by Ultrasonic Impact Treatment: Microstructure, Hardness and Corrosion

    Science.gov (United States)

    Khripta, N. I.; Karasevska, O. P.; Mordyuk, B. N.

    2017-11-01

    Near-surface layers in Zr-18%Nb alloy were modified using ultrasonic impact treatment (UIT). The effects of the UIT processing time on a microstructural formation, omega/alpha precipitations, microhardness and corrosion are analyzed. XRD analysis, TEM and SEM observations and EDX characterization allow establishing the links between the microstructure, microhardness and corrosion behavior of the surface layers formed. At the strain extent up to e ≈ 0.3, structural formation occurs under influence of deformation induced heating, which facilitates omega precipitation in beta phase and mechanically induced oxygen transport and oxide formation. XRD analysis reveals moderate compressive residual stresses (- 160 MPa) and pronounced {110} texture after the UIT process. Generation of dislocations and hindering of their movement by nanoscale omega precipitates manifest themselves as the broadening of diffraction peaks occurred mainly owing to the lattice microstrains, and they provide marked strain hardening. The enhanced anticorrosion properties of Zr-18%Nb alloy in saline solution were concluded to be a result of the formation of a protective oxide film, {110} texture and compressive stresses.

  6. Magnetic Signatures of Fine-scale Processes in the Ocean Surface Layer

    Science.gov (United States)

    Soloviev, A.; Dean, C.; Avera, W. E.

    2015-12-01

    Fine-scale processes in the upper ocean turbulent boundary layer may have a measurable electromagnetic signature. In order to study magnetic signatures of these fine-scale processes, we have applied a magnetohydrodynamic (MHD) model combining a 3D computational fluid dynamics model and electromagnetic block, based on ANSYS Fluent software. In addition, the hydrodynamic component of the MHD model is coupled with a radar imaging algorithm, which potentially provides a link to synthetic aperture radar (SAR) satellite imagery. Capabilities of this model have been demonstrated using a simulation and observation of an internal wave soliton in the Straits of Florida, observed with in situ instrumentation (ADCP mooring) and COSMO Sky Med (SAR) satellite image. We have applied this model to study magnetic signatures of surface waves, freshwater lenses, spatially coherent organized motions in the near-surface layer of the ocean (Langmuir circulation and ramp-like structures), and bio-turbulence induced by diel vertical migrations of zooplankton in some areas of the ocean. Investigation of electromagnetic signatures in upper ocean processes offers a valuable new prospect in air-sea interaction.

  7. In situ formation of graphene layers on graphite surfaces for efficient anodes of microbial fuel cells.

    Science.gov (United States)

    Tang, Jiahuan; Chen, Shanshan; Yuan, Yong; Cai, Xixi; Zhou, Shungui

    2015-09-15

    Graphene can be used to improve the performance of the anode in a microbial fuel cell (MFC) due to its good biocompatibility, high electrical conductivity and large surface area. However, the chemical production and modification of the graphene on the anode are environmentally hazardous because of the use of various harmful chemicals. This study reports a novel method based on the electrochemical exfoliation of a graphite plate (GP) for the in situ formation of graphene layers on the surface of a graphite electrode. When the resultant graphene-layer-based graphite plate electrode (GL/GP) was used as an anode in an MFC, a maximum power density of 0.67 ± 0.034 W/m(2) was achieved. This value corresponds to 1.72-, 1.56- and 1.26-times the maximum power densities of the original GP, exfoliated-graphene-modified GP (EG/GP) and chemically-reduced-graphene-modified GP (rGO/GP) anodes, respectively. Electrochemical measurements revealed that the high performance of the GL/GP anode was attributable to its macroporous structure, improved electron transfer and high electrochemical capacitance. The results demonstrated that the proposed method is a facile and environmentally friendly synthesis technique for the fabrication of high-performance graphene-based electrodes for use in microbial energy harvesting. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Picosecond laser ultrasonic measurements of surface waves on patterned layered nanostructures

    Science.gov (United States)

    Gartenstein, Sam; James, Molly; Mahat, Sushant; Szwed, Erik; Daly, Brian; Cui, Weili; Antonelli, George

    We report ultrafast optical pump-probe measurements of 5 - 25 GHz surface acoustic waves (SAWs) on patterned layered nanostructures. These very high frequency SAWs were generated and detected on the following patterned film stack: 25 nm physically vapor deposited Al / 60-110 nm thermally grown a-SiO2 / Si (100) substrate. The Al was etched to form lines of rectangular cross section with pitches ranging from 1000 nm down to 140 nm and the lines were oriented parallel to the [110] direction on the wafer surface. The absorption of ultrafast pulses from a Ti:sapphire oscillator operating at 800 nm generated SAWs that were detected by time-delayed probe pulses from the same oscillator via a reflectivity change (ΔR). The SAW frequency increased with decreasing pitch in a non-linear fashion due to dispersion of the wave caused by the presence of the oxide layer. We also experimentally demonstrate the traveling of the SAW's by separating the focused pump and probe laser spots by several microns. We compare the results to coarse-grained molecular dynamics simulations and simplified calculations using isotropic elasticity theory. This work was supported by NSF Award DMR1206681.

  9. Rapid removal of plutonium from the oceanic surface layer by zooplankton faecal pellets

    International Nuclear Information System (INIS)

    Higgo, J.J.W.; Cherry, R.D.; Heyraud, M.; Fowler, S.W.

    1977-01-01

    In view of the possibility that increasing quantities of Pu may in due course be introduced into the marine environment, it is important to have a detailed knowledge of its oceanic behaviour. It has been suggested that algae and perhaps the phytoplanktonic mass may have an important role in determining the chemical and physical forms of Pu predominant in the ocean. The role of the zooplanktonic mass has not been investigated in detail, but it is known that for several elements zooplankton metabolism may be an important biological factor in the removal of elements from the surface layers of the ocean. The particular importance of zooplankton faecal pellets in this process has been stressed, and it has been found that M. norvegica is rich in the naturally-occurring α-emitter 210 Po when compared with whole organism levels. A study is here described for Pu, and it is reported that M. norvegica faecal pellets are relatively rich in Pu. It is suggested that zooplankton faecal pellet deposition might be an important vector in the vertical oceanic transport of this element. Experimental details are given and results are shown in tabular form. The implications of the high concentrations of Pu in faecal pellets are described, and rough estimates are made for the removal time of Pu from the upper mixed ocean layers by zooplankton pellets alone; the result is 3.6 years. It is suggested that faecal pellets may have a significant role in the removal of Pu from the surface layers of the sea. (U.K.)

  10. Rational Design of Hyperbranched Nanowire Systems for Tunable Superomniphobic Surfaces Enabled by Atomic Layer Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Bielinski, Ashley R.; Boban, Mathew; He, Yang; Kazyak, Eric; Lee, Duck H.; Wang, Chongmin; Tuteja, Anish; Dasgupta, Neil P.

    2017-01-24

    A method for tunable control of geometry in hyperbranched ZnO nanowire (NW) systems is reported, which enables the rational design and fabrication of superomniphobic surfaces. Branched NWs with tunable density and orientation were grown via a sequential hydrothermal process, in which atomic layer deposition (ALD) was used for NW seeding, disruption of epitaxy, and selective blocking of NW nucleation. This approach allows for the rational design and optimization of three-level hierarchical structures, in which the geometric parameters of each level of hierarchy can be individually controlled. We demonstrate the coupled relationships between geometry and contact angle for a variety of liquids, which is supported by mathematical models of structural superomniphobicity. The highest performing superomniphobic surface was designed with three levels of hierarchy and achieved the following advancing/receding contact angles, water: 172°/170°, hexadecane: 166°/156°, octane: 162°/145°, and heptane: 160°/130°. Low surface tension liquids were shown to bounce off the surface from a height of 7 cm without breaking through and wetting. This approach demonstrates the power of ALD as an enabling technique for hierarchical materials by design, spanning the macro, micro, and nano length scales.

  11. Excellent c-Si surface passivation by low-temperature atomic layer deposited titanium oxide

    International Nuclear Information System (INIS)

    Liao, Baochen; Hoex, Bram; Aberle, Armin G.; Bhatia, Charanjit S.; Chi, Dongzhi

    2014-01-01

    In this work, we demonstrate that thermal atomic layer deposited (ALD) titanium oxide (TiO x ) films are able to provide a—up to now unprecedented—level of surface passivation on undiffused low-resistivity crystalline silicon (c-Si). The surface passivation provided by the ALD TiO x films is activated by a post-deposition anneal and subsequent light soaking treatment. Ultralow effective surface recombination velocities down to 2.8 cm/s and 8.3 cm/s, respectively, are achieved on n-type and p-type float-zone c-Si wafers. Detailed analysis confirms that the TiO x films are nearly stoichiometric, have no significant level of contaminants, and are of amorphous nature. The passivation is found to be stable after storage in the dark for eight months. These results demonstrate that TiO x films are also capable of providing excellent passivation of undiffused c-Si surfaces on a comparable level to thermal silicon oxide, silicon nitride, and aluminum oxide. In addition, it is well known that TiO x has an optimal refractive index of 2.4 in the visible range for glass encapsulated solar cells, as well as a low extinction coefficient. Thus, the results presented in this work could facilitate the re-emergence of TiO x in the field of high-efficiency silicon wafer solar cells.

  12. The warmer the ocean surface, the shallower the mixed layer. How much of this is true?

    Science.gov (United States)

    Somavilla, R; González-Pola, C; Fernández-Diaz, J

    2017-09-01

    Ocean surface warming is commonly associated with a more stratified, less productive, and less oxygenated ocean. Such an assertion is mainly based on consistent projections of increased near-surface stratification and shallower mixed layers under global warming scenarios. However, while the observed sea surface temperature (SST) is rising at midlatitudes, the concurrent ocean record shows that stratification is not unequivocally increasing nor is MLD shoaling. We find that while SST increases at three study areas at midlatitudes, stratification both increases and decreases, and MLD deepens with enhanced deepening of winter MLDs at rates over 10 m  decade-1. These results rely on the estimation of several MLD and stratification indexes of different complexity on hydrographic profiles from long-term hydrographic time-series, ocean reanalysis, and Argo floats. Combining this information with estimated MLDs from buoyancy fluxes and the enhanced deepening/attenuation of the winter MLD trends due to changes in the Ekman pumping, MLD variability involves a subtle interplay between circulation and atmospheric forcing at midlatitudes. Besides, it is highlighted that the density difference between the surface and 200 m, the most widely used stratification index, should not be expected to reliably inform about changes in the vertical extent of mixing.

  13. Excellent c-Si surface passivation by low-temperature atomic layer deposited titanium oxide

    Science.gov (United States)

    Liao, Baochen; Hoex, Bram; Aberle, Armin G.; Chi, Dongzhi; Bhatia, Charanjit S.

    2014-06-01

    In this work, we demonstrate that thermal atomic layer deposited (ALD) titanium oxide (TiOx) films are able to provide a—up to now unprecedented—level of surface passivation on undiffused low-resistivity crystalline silicon (c-Si). The surface passivation provided by the ALD TiOx films is activated by a post-deposition anneal and subsequent light soaking treatment. Ultralow effective surface recombination velocities down to 2.8 cm/s and 8.3 cm/s, respectively, are achieved on n-type and p-type float-zone c-Si wafers. Detailed analysis confirms that the TiOx films are nearly stoichiometric, have no significant level of contaminants, and are of amorphous nature. The passivation is found to be stable after storage in the dark for eight months. These results demonstrate that TiOx films are also capable of providing excellent passivation of undiffused c-Si surfaces on a comparable level to thermal silicon oxide, silicon nitride, and aluminum oxide. In addition, it is well known that TiOx has an optimal refractive index of 2.4 in the visible range for glass encapsulated solar cells, as well as a low extinction coefficient. Thus, the results presented in this work could facilitate the re-emergence of TiOx in the field of high-efficiency silicon wafer solar cells.

  14. Improved adhesion of superhydrophobic layer on metal surfaces via one step spraying method

    Directory of Open Access Journals (Sweden)

    Wael I. El Dessouky

    2017-03-01

    Full Text Available Superhydrophobic metal substrates have been fabricated by a simple spraying method. The processes of decreasing surface free energy and increasing surface roughness have been accomplished in one step via the addition of functionalized silica (silica nano particles with octyltriethoxysilane to adhesive polymer. The method is simple, cost-effective and can be applied on the large industrial scale. Scanning electron microscopy (SEM was used for surface morphology analysis, showing the roughness produced by surface treatment. The wettability of the micro-nano silica film varied from hydrophilicity (water contact angle 88° to superhydrophobicity (water contact angle 156.9°, while sliding contact angles dramatically decreased (<5° by adding Functionalized silica and/or adhesive polymer. Roughness increased with silica increment which improves the wettability. The coatings were electrochemically characterized by electrochemical impedance spectroscopy (EIS and Tafel polarization curves; it was found that both systems had good performance against corrosion in 3.5% sodium chloride solution. Furthermore, the stability of the coated layer on copper substrate was investigated.

  15. The warmer the ocean surface, the shallower the mixed layer. How much of this is true?

    Science.gov (United States)

    Somavilla, R.; González-Pola, C.; Fernández-Diaz, J.

    2017-09-01

    Ocean surface warming is commonly associated with a more stratified, less productive, and less oxygenated ocean. Such an assertion is mainly based on consistent projections of increased near-surface stratification and shallower mixed layers under global warming scenarios. However, while the observed sea surface temperature (SST) is rising at midlatitudes, the concurrent ocean record shows that stratification is not unequivocally increasing nor is MLD shoaling. We find that while SST increases at three study areas at midlatitudes, stratification both increases and decreases, and MLD deepens with enhanced deepening of winter MLDs at rates over 10 m decade-1. These results rely on the estimation of several MLD and stratification indexes of different complexity on hydrographic profiles from long-term hydrographic time-series, ocean reanalysis, and Argo floats. Combining this information with estimated MLDs from buoyancy fluxes and the enhanced deepening/attenuation of the winter MLD trends due to changes in the Ekman pumping, MLD variability involves a subtle interplay between circulation and atmospheric forcing at midlatitudes. Besides, it is highlighted that the density difference between the surface and 200 m, the most widely used stratification index, should not be expected to reliably inform about changes in the vertical extent of mixing.

  16. Dynamic Leidenfrost temperature on micro-textured surfaces: Acoustic wave absorption into thin vapor layer

    Science.gov (United States)

    Jerng, Dong Wook; Kim, Dong Eok

    2018-01-01

    The dynamic Leidenfrost phenomenon is governed by three types of pressure potentials induced via vapor hydrodynamics, liquid dynamic pressure, and the water hammer effect resulting from the generation of acoustic waves at the liquid-vapor interface. The prediction of the Leidenfrost temperature for a dynamic droplet needs quantitative evaluation and definition for each of the pressure fields. In particular, the textures on a heated surface can significantly affect the vapor hydrodynamics and the water hammer pressure. We present a quantitative model for evaluating the water hammer pressure on micro-textured surfaces taking into account the absorption of acoustic waves into the thin vapor layer. The model demonstrates that the strength of the acoustic flow into the liquid droplet, which directly contributes to the water hammer pressure, depends on the magnitude of the acoustic resistance (impedance) in the droplet and the vapor region. In consequence, the micro-textures of the surface and the increased spacing between them reduce the water hammer coefficient ( kh ) defined as the ratio of the acoustic flow into the droplet to total generated flow. Aided by numerical calculations that solve the laminar Navier-Stokes equation for the vapor flow, we also predict the dynamic Leidenfrost temperature on a micro-textured surface with reliable accuracy consistent with the experimental data.

  17. Surface element segregation and electrical conductivity of lithium layered transition-metal oxide cathode materials

    Science.gov (United States)

    Li, Guohua; Li, Qi; Li, Liping; Fan, Jianming; Ge, Qingqin; Xie, Dongjiu; Zheng, Jing; Li, Guangshe

    2018-01-01

    Surface element segregation and electric conductivity are critical in determining lithium storage ability of given cathode materials, which are poorly understood and not correlated with the structure and overall performance. Here, layered lithium transition-metal oxides, one of the state-of-the-art cathode materials for lithium ion batteries are chosen to study. A serial of LiNixCo1-2xMnxO2 samples were prepared via a solid state reaction and subsequently characterized by XRD in conjunction with structural refinement, XPS depth profiling, and AC impedance spectroscopy. Slightly different expansion rates are observed for lattice parameters (a and c/3) with varying of Ni content, which is attributed to the increase of average metal-ion radius and an increase of eg electron that enhances the columbic repulsion between transition metal and oxygen atoms. XPS depth profiling results show that surface composition is significantly deviated from bulk, in which Ni and Mn atoms tend to enrich in the surface region, while Co element is relatively deficient. Further, surface element segregation is alleviated by the increase of Ni/Mn content. Moreover, increasing the Ni/Mn content also raises the activation energy of bulk conduction.

  18. Revitalization of the ESL Program on the Rockville Campus of Montgomery College, and the Matter of Credit for ESL Courses.

    Science.gov (United States)

    Bolton, John K.

    In 1990-91, the Rockville Campus (RC) of Montgomery College (MC) in Maryland, revised its English-as-a-Second-Language (ESL) program to make it more responsive to student needs and begin offering ESL courses for institutional credit in fall 1991. Faculty at MC's Takoma Park Campus (TPC), however, objected to RC's proposed changes, particularly to…

  19. Remote sensing of the surface layer dynamics of a stratified lake

    Science.gov (United States)

    Steissberg, Todd Eugene

    . In situ velocity profiles of a cool-core eddy revealed elevated velocities up to 12 cm/s throughout the surface mixed layer, rotating with depth in an Ekman spiral. Average upward vertical velocities approaching 0.58 cm/s indicated Ekman pumping and enhanced stability. A time series of moderate-resolution WST maps confirmed the eddy's stability, showing it persisted 3.5 days until it abruptly disintegrated, spreading its contents across the surface layer. The findings suggest upwelling and eddies contribute to the patchiness of the surface layer.

  20. ESL Teachers/ESL Students: Looking at Autoethnography through the Lens of Personetics

    Science.gov (United States)

    Lapidus, Alec; Kaveh, Yalda M.; Hirano, Mamiko

    2013-01-01

    This qualitative, naturalistic study examines thoughts expressed in autoethnographies and accompanying notes written by ESL teachers/learners who are enrolled in a graduate teacher education program in the US. These data are then juxtaposed with the Freirean idea that English learners can be empowered if they analyze their personal paths…

  1. Investigation of structural transformations in surface layer of phosphate glasses incorporating radiactive wastes

    International Nuclear Information System (INIS)

    Aloj, A.S.; Kolycheva, T.I.; Trofimenko, A.V.; Shashukov, E.A.

    1985-01-01

    The objective of the paper was to clarify possibilities of detection of structural transformations initial stages on the surface of phosphate glasses using the method of infrared reflection spectroscopy. Phase composition of crystalline compounds formed in surface glass layer is determined by the method of X-ray diffraction. All experiments were performed using sodium alumophosphate glass comprising the model mixture of fission product of the following compostion (mass%): Na 2 O-22.0, Al 2 O 3 -14.0, P 2 O 5 -50.0, Fe 2 O 3 -3.5, Cs 2 O-3.5, SrO-3.0, Ln 2 O 3 -4.0, where Ln 2 O 3 is a mixture of cerium, lanthanum and europium oxides. Sample preparation were carried out by molten glass deposition on platinum forms 15mm in diameter and 4mm thick. Glasses were treated within the 600-400deg.C temperature range. Fixing of processes accompanied by structural transformations was accomplished the method of rapid cooling. It has been shown that phase transformations, taking place in investigated phosphate glasses under the action of heat, result in deterioration of chemical properties. Analysis of IR spectra has revealed that emergence of structural transformations in surface layer of investigated glasses results in variation of a ratio of 1060 and 1140cm - 1 reflection band intensities. Experimental dependences of the time of beginning of variation of 1060 and 1140cm - 1 bands relative intensity on temperature are presented. Insemilogarithmic coordinates this dependence has a straight line form within the 600-400 deg C temperature range and is desc ribed by the following formular: lg r=-7.41+5.70x10 3 x1/T, where r is the time of process beginning, h. Extrapolation of established to the region of low temperature is shown. Competence of such extrapolation may be confirmed in the course of further experiments

  2. Soil surface organic layers in Arctic Alaska: spatial distribution, rates of formation, and microclimatic effects

    Science.gov (United States)

    Baughman, Carson A.; Mann, Daniel H.; Verbyla, David L.; Kunz, Michael L.

    2015-01-01

    Organic layers of living and dead vegetation cover the ground surface in many permafrost landscapes and play important roles in ecosystem processes. These soil surface organic layers (SSOLs) store large amounts of carbon and buffer the underlying permafrost and its contained carbon from changes in aboveground climate. Understanding the dynamics of SSOLs is a prerequisite for predicting how permafrost and carbon stocks will respond to warming climate. Here we ask three questions about SSOLs in a representative area of the Arctic Foothills region of northern Alaska: (1) What environmental factors control the thickness of SSOLs and the carbon they store? (2) How long do SSOLs take to develop on newly stabilized point bars? (3) How do SSOLs affect temperature in the underlying ground? Results show that SSOL thickness and distribution correlate with elevation, drainage area, vegetation productivity, and incoming solar radiation. A multiple regression model based on these correlations can simulate spatial distribution of SSOLs and estimate the organic carbon stored there. SSOLs develop within a few decades after a new, sandy, geomorphic surface stabilizes but require 500–700 years to reach steady state thickness. Mature SSOLs lower the growing season temperature and mean annual temperature of the underlying mineral soil by 8 and 3°C, respectively. We suggest that the proximate effects of warming climate on permafrost landscapes now covered by SSOLs will occur indirectly via climate's effects on the frequency, extent, and severity of disturbances like fires and landslides that disrupt the SSOLs and interfere with their protection of the underlying permafrost.

  3. Polydopamine as an intermediate layer for silver and hydroxyapatite immobilisation on metallic biomaterials surface

    Energy Technology Data Exchange (ETDEWEB)

    Saidin, Syafiqah, E-mail: syafiqahsaidin@gmail.com [Medical Implant Technology Group, Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru (Malaysia); Chevallier, Pascale, E-mail: pascale.chevallier@crsfa.ulaval.ca [Laboratory for Biomaterials and Bioengineering, Department of Mining, Metallurgical and Materials Engineering and University Hospital Research Center, Laval University, Quebec City, QC, G1V 0A6 (Canada); Abdul Kadir, Mohammed Rafiq, E-mail: rafiq@biomedical.utm.my [Medical Implant Technology Group, Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru (Malaysia); Hermawan, Hendra, E-mail: hendra.hermawan@biomedical.utm.my [Medical Implant Technology Group, Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru (Malaysia); Mantovani, Diego, E-mail: Diego.Mantovani@gmn.ulaval.ca [Laboratory for Biomaterials and Bioengineering, Department of Mining, Metallurgical and Materials Engineering and University Hospital Research Center, Laval University, Quebec City, QC, G1V 0A6 (Canada)

    2013-12-01

    Hydroxyapatite (HA) coated implant is more susceptible to bacterial infection as the micro-structure surface which is beneficial for osseointegration, could also become a reservoir for bacterial colonisation. The aim of this study was to introduce the antibacterial effect of silver (Ag) to the biomineralised HA by utilising a polydopamine film as an intermediate layer for Ag and HA immobilisation. Sufficient catechol groups in polydopamine were required to bind chemically stainless steel 316 L, Ag and HA elements. Different amounts of Ag nanoparticles were metallised on the polydopamine grafted stainless steel by varying the immersion time in silver nitrate solution from 12 to 24 h. Another polydopamine layer was then formed on the metallised film, followed by surface biomineralisation in 1.5 Simulated Body Fluid (SBF) solution for 3 days. Several characterisation techniques including X-Ray Photoelectron Spectroscopy, Atomic Force Microscopy, Scanning Electron Microscopy and Contact Angle showed that Ag nanoparticles and HA agglomerations were successfully immobilised on the polydopamine film through an element reduction process. The Ag metallisation at 24 h has killed the viable bacteria with 97.88% of bactericidal ratio. The Ag was ionised up to 7 days which is crucial to prevent bacterial infection during the first stage of implant restoration. The aged functionalised films were considered stable due to less alteration of its chemical composition, surface roughness and wettability properties. The ability of the functionalised film to coat complex and micro scale metal make it suitable for dental and orthopaedic implants application. - Highlights: • Successful immobilisation of Ag and HA on SS316L functionalised with polydopamine • Development of antibacterial film at 97.88% bactericidal ratio • The functionalised films were stable under ageing test at 7 days.

  4. Polydopamine as an intermediate layer for silver and hydroxyapatite immobilisation on metallic biomaterials surface

    International Nuclear Information System (INIS)

    Saidin, Syafiqah; Chevallier, Pascale; Abdul Kadir, Mohammed Rafiq; Hermawan, Hendra; Mantovani, Diego

    2013-01-01

    Hydroxyapatite (HA) coated implant is more susceptible to bacterial infection as the micro-structure surface which is beneficial for osseointegration, could also become a reservoir for bacterial colonisation. The aim of this study was to introduce the antibacterial effect of silver (Ag) to the biomineralised HA by utilising a polydopamine film as an intermediate layer for Ag and HA immobilisation. Sufficient catechol groups in polydopamine were required to bind chemically stainless steel 316 L, Ag and HA elements. Different amounts of Ag nanoparticles were metallised on the polydopamine grafted stainless steel by varying the immersion time in silver nitrate solution from 12 to 24 h. Another polydopamine layer was then formed on the metallised film, followed by surface biomineralisation in 1.5 Simulated Body Fluid (SBF) solution for 3 days. Several characterisation techniques including X-Ray Photoelectron Spectroscopy, Atomic Force Microscopy, Scanning Electron Microscopy and Contact Angle showed that Ag nanoparticles and HA agglomerations were successfully immobilised on the polydopamine film through an element reduction process. The Ag metallisation at 24 h has killed the viable bacteria with 97.88% of bactericidal ratio. The Ag was ionised up to 7 days which is crucial to prevent bacterial infection during the first stage of implant restoration. The aged functionalised films were considered stable due to less alteration of its chemical composition, surface roughness and wettability properties. The ability of the functionalised film to coat complex and micro scale metal make it suitable for dental and orthopaedic implants application. - Highlights: • Successful immobilisation of Ag and HA on SS316L functionalised with polydopamine • Development of antibacterial film at 97.88% bactericidal ratio • The functionalised films were stable under ageing test at 7 days

  5. Growth, intermixing, and surface phase formation for zinc tin oxide nanolaminates produced by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Hägglund, Carl, E-mail: carl.hagglund@angstrom.uu.se [Department of Chemical Engineering, Stanford University, Stanford, California 94305 and Department of Engineering Sciences, Division of Solid State Electronics, Uppsala University, 75121 Uppsala (Sweden); Grehl, Thomas; Brongersma, Hidde H. [ION-TOF GmbH, Heisenbergstraße 15, 48149 Münster (Germany); Tanskanen, Jukka T.; Mullings, Marja N.; Mackus, Adriaan J. M.; MacIsaac, Callisto; Bent, Stacey Francine, E-mail: sbent@stanford.edu [Department of Chemical Engineering, Stanford University, Stanford, California 94305 (United States); Yee, Ye Sheng [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Clemens, Bruce M. [Department of Material Science and Engineering, Stanford University, Stanford, California 94305 (United States)

    2016-03-15

    A broad and expanding range of materials can be produced by atomic layer deposition at relatively low temperatures, including both oxides and metals. For many applications of interest, however, it is desirable to grow more tailored and complex materials such as semiconductors with a certain doping, mixed oxides, and metallic alloys. How well such mixed materials can be accomplished with atomic layer deposition requires knowledge of the conditions under which the resulting films will be mixed, solid solutions, or laminated. The growth and lamination of zinc oxide and tin oxide is studied here by means of the extremely surface sensitive technique of low energy ion scattering, combined with bulk composition and thickness determination, and x-ray diffraction. At the low temperatures used for deposition (150 °C), there is little evidence for atomic scale mixing even with the smallest possible bilayer period, and instead a morphology with small ZnO inclusions in a SnO{sub x} matrix is deduced. Postannealing of such laminates above 400 °C however produces a stable surface phase with a 30% increased density. From the surface stoichiometry, this is likely the inverted spinel of zinc stannate, Zn{sub 2}SnO{sub 4}. Annealing to 800 °C results in films containing crystalline Zn{sub 2}SnO{sub 4}, or multilayered films of crystalline ZnO, Zn{sub 2}SnO{sub 4}, and SnO{sub 2} phases, depending on the bilayer period.

  6. On the effectiveness of surface assimilation in probabilistic nowcasts of planetary boundary layer profiles

    Science.gov (United States)

    Rostkier-Edelstein, Dorita; Hacker, Joshua

    2013-04-01

    Surface observations comprise a wide, non-expensive and reliable source of information about the state of the near-surface planetary boundary layer (PBL). Operational data assimilation systems have encountered several difficulties in effectively assimilating them, among others due to their local-scale representativeness, the transient coupling between the surface and the atmosphere aloft and the balance constraints usually used. A long-term goal of this work is to find an efficient system for probabilistic PBL nowcasting that can be employed wherever surface observations are present. Earlier work showed that surface observations can be an important source of information with a single column model (SCM) and an ensemble filter (EF). Here we extend that work to quantify the probabilistic skill of ensemble SCM predictions with a model including added complexity. We adopt a factor separation analysis to quantify the contribution of surface assimilation relative to that of selected model components (parameterized radiation and externally imposed horizontal advection) to the probabilistic skill of the system, and of any beneficial or detrimental interactions between them. To assess the real utility of the flow-dependent covariances estimated with the EF and of the SCM of the PBL we compare the skill of the SCM/EF system to that of a reference one based on climatological covariances and a 30-min persistence model. It consists of a dressing technique, whereby a deterministic 3D mesoscale forecast (e.g. from WRF model) is adjusted and dressed with uncertainty using a seasonal sample of mesoscale forecasts and surface forecast errors. Results show that assimilation of surface observations can improve deterministic and probabilistic profile predictions more significantly than major model improvements. Flow-dependent covariances estimated with the SCM/EF show clear advantage over the use of climatological covariances when the flow is characterized by wide variability, when

  7. Preparation and microstructure characteristics of low-temperature bainite in surface layer of low carbon gear steel

    Science.gov (United States)

    Zhang, P.; Zhang, F. C.; Wang, T. S.

    2011-06-01

    A kind of technology was proposed for the development of low-temperature bainitic microstructure in the surface layer of low-carbon gear steel 20CrMnMo, which is based on carburization and succedent low-temperature austempering. The carbon content in the surface carburization layer increases to 0.81 wt.%, making the martensite starting point depressed. Low-temperature bainite formed in the carburization layer and lath martensite with low carbon content in the center by austempering at a low temperature slightly higher than the martensite starting point of the surface layer. Aluminum is added as alloying elements with the purpose of enhancing the driving force of bainitic transformation and retarding the precipitation of cementite during austempering. With the excellent toughness of low-temperature bainite, this low-temperature austempering technology could be a potential substitute of the traditional quenching and tempering heat treatment in the manufacture of gear.

  8. Dependence of the structure of ion-modified NiTi single crystal layers on the orientation of irradiated surface

    Science.gov (United States)

    Poletika, T. M.; Meisner, L. L.; Girsova, S. L.; Tverdokhlebova, A. V.; Meisner, S. N.

    2017-07-01

    The composition and structure of Si layers implanted into titanium nickelide single crystals with different orientations relative to the ion beam propagation direction have been studied using Auger electron spectroscopy and transmission electron microscopy. The role of the "soft" [111]B2 and "hard" [001]B2 NiTi orientations in the formation of the structure of ion-modified surface layer, as well as the defect structure of the surface layers of the single crystals, has been revealed. Orientation effects of selective sputtering and channeling of ions, which control the composition and thickness of the oxide and amorphous layers being formed, ion and impurity penetration depth, as well as the concentration profile of the Ni distribution over the surface, have been detected.

  9. A bio-enabled maximally mild layer-by-layer Kapton surface modification approach for the fabrication of all-inkjet-printed flexible electronic devices

    Science.gov (United States)

    Fang, Yunnan; Hester, Jimmy G. D.; Su, Wenjing; Chow, Justin H.; Sitaraman, Suresh K.; Tentzeris, Manos M.

    2016-12-01

    A bio-enabled, environmentally-friendly, and maximally mild layer-by-layer approach has been developed to surface modify inherently hydrophobic Kapton HN substrates to allow for great printability of both water- and organic solvent-based inks thus facilitating the full-inkjet-printing of flexible electronic devices. Different from the traditional Kapton surface modification approaches which are structure-compromising and use harsh conditions to target, and oxidize and/or remove part of, the surface polyimide of Kapton, the present Kapton surface modification approach targeted the surface electric charges borne by its additive particles, and was not only the first to utilize environmentally-friendly clinical biomolecules to build up a thin film of protamine-heparin complex on Kapton, but also the first to be conducted under minimally destructive and maximally mild conditions. Besides, for electrically charged ink particles, the present surface modification method can enhance the uniformity of the inkjet-printed films by reducing the “coffee ring effect”. As a proof-of-concept demonstration, reduced graphene oxide-based gas sensors, which were flexible, ultra-lightweight, and miniature-sized, were fully-inkjet-printed on surface modified Kapton HN films and tested for their sensitivity to dimethyl methylphosphonate (a nerve agent simulant). Such fabricated sensors survived a Scotch-tape peel test and were found insensitive to repeated bending to a small 0.5 cm radius.

  10. Composite Layers “MgAl Intermetalic Layer / PVD Coating” Obtained On The AZ91D Magnesium Alloy By Different Hybrid Surface Treatment Methods

    Directory of Open Access Journals (Sweden)

    Smolik J.

    2015-06-01

    Full Text Available Magnesium alloys have very interesting physical properties which make them ‘materials of the future’ for tools and machine components in many industry areas. However, very low corrosion and tribological resistance of magnesium alloys hampers the implementation of this material in the industry. One of the methods to improve the properties of magnesium alloys is the application of the solutions of surface engineering like hybrid technologies. In this paper, the authors compare the tribological and corrosion properties of two types of “MgAlitermetalic / PVD coating” composite layers obtained by two different hybrid surface treatment technologies. In the first configuration, the “MgAlitermetalic / PVD coating” composite layer was obtained by multisource hybrid surface treatment technology combining magnetron sputtering (MS, arc evaporation (AE and vacuum heating methods. The second type of a composite layer was prepared using a hybrid technology combined with a diffusion treatment process in Al-powder and the electron beam evaporation (EB method. The authors conclude, that even though the application of „MgAlitermetalic / PVD coating” composite layers can be an effective solution to increase the abrasive wear resistance of magnesium alloys, it is not a good solution to increase its corrosion resistance.

  11. Three-dimensional structure of the surface layer protein of Aquaspirilium serpens VHA determined by electron crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Dickson, M.R.; Downing, K.H.; Wu, W.H.; Glaeser, R.M.

    1986-09-01

    The three-dimensional structure of the protein which forms the S layer of Aquaspirilium serpens strain VHA has been determined by electron microscopy. Structures have been reconstructed to a resolution of about 1.6 nm for single-layered specimens and about 4 nm for two-layered specimens. The structure, which has hexagonal symmetry, consists of a core in the shape of a cup, with six projections arising from the rim of the cup to join adjacent subunits at the threefold symmetry axes. The model is consistent with edge views of the S layer which have been obtained in this and other work. It is now clear from this work and from three-dimensional reconstructions of other bacterial S layers that a wide diversity exists in the morphology of surface layers.

  12. Three-dimensional structure of the surface layer protein of Aquaspirillum serpens VHA determined by electron crystallography.

    Science.gov (United States)

    Dickson, M R; Downing, K H; Wu, W H; Glaeser, R M

    1986-09-01

    The three-dimensional structure of the protein which forms the S layer of Aquaspirillum serpens strain VHA has been determined by electron microscopy. Structures have been reconstructed to a resolution of about 1.6 nm for single-layered specimens and about 4 nm for two-layered specimens. The structure, which has hexagonal symmetry, consists of a core in the shape of a cup, with six projections arising from the rim of the cup to join adjacent subunits at the threefold symmetry axes. The model is consistent with edge views of the S layer which have been obtained in this and other work. It is now clear from this work and from three-dimensional reconstructions of other bacterial S layers that a wide diversity exists in the morphology of surface layers.

  13. Characteristics of the surface layer above a row crop in the presence of local advection

    Energy Technology Data Exchange (ETDEWEB)

    Figuerola, P.I. [Universidad de Buenos Aires, Buenos Aires (Argentina)]. E-mail: figuerol@at.fcen.uba.ar; Berliner, P.R. [Blaustein Institute for Desert Research, Ben-Gurion University of the Negev (Israel)

    2006-04-15

    In some arid land, the irrigated fields are not contiguous and are surrounded by large patches of bare land. During the summer time and rainless season, the solar radiation flux is high and the surface temperature during daylight in the dry bare areas, is much higher than that of the air. The sensible heat generated over these areas may be advected to the irrigated fields. The crops are usually planted in rows and the irrigation systems used (trickle) do not wet the whole surface, the dry bare soil between the rows may develop high soil surface temperatures and lead to convective activity inside the canopy above the bare soil. Advection from the surrounding fields and convective activity inside the canopy affect the layer above the crop. We studied the surface layer above an irrigated tomato field planted in Israel's Negev desert. The crop was planted in rows, trickle irrigated and the distance between the outer edges of two adjacent rows was 0.36 m at the time of measurement. The gradients in temperature and water vapor pressure were obtained at various heights above the canopy using a Bowen ratio machine. The residual in the energy balance equation was used as a criterion to determine the equilibrium layer. During the morning, unstable conditions prevail, and the equilibrium layer was between Z/h {approx} 1.9 and 2.4. In some particular circumstances, in the late morning, the bare soil between the rows reached extremely high temperatures and during conditions with low wind speeds free convection was identified. During these hours the residuals of the energy budget to the heights Z/h = 1.5 and 2.4 were significantly different from zero and an extremely large variability was evident for the Z/h = 3.2 layer. Local advection took place during the afternoon resulting in an increase in the stability of the uppermost measured layer and propagated slowly downwards. The equilibrium layer was between Z/h {approx} 1.5 to 2.4. The residuals were significantly different

  14. Surface layer determination for the Si spheres of the Avogadro project

    Science.gov (United States)

    Busch, I.; Azuma, Y.; Bettin, H.; Cibik, L.; Fuchs, P.; Fujii, K.; Krumrey, M.; Kuetgens, U.; Kuramoto, N.; Mizushima, S.

    2011-04-01

    For the accurate determination of the Avogadro constant, two 28Si spheres were produced, whose macroscopic density, in addition to other values, must be determined. To make a contribution to the new definition of the kilogram, a relative standard uncertainty of less than 2 × 10-8 has to be achieved. Each silicon surface is covered by a surface layer (SL). Consequently, correction parameters for the SL are determined to be applied to the mass and volume determination of the enriched spheres. With the use of a large set of surface analysing techniques, the structure of the SL is investigated. An unexpected metallic contamination existing on the sphere surface enlarges the uncertainty contribution of the correction parameters above the originally targeted value of 1 × 10-8. In the framework of this investigation this new obstacle is resolved in two ways. A new combination of analytical methods is applied to measure the SL mass mSL and the thickness dSL, including this new contamination, with an uncertainty of u(mSL) = 14.5 µg and 14.4 µg, respectively, and u(dSL) = 0.33 nm and 0.32 nm for the 28Si spheres AVO28-S5 and AVO28-S8, respectively. In the second part of the work, the chemical composition of these metallic contaminations is found to be Cu, Ni and Zn silicide compounds. For the removal of this contamination, a special procedure is developed, tested and applied to the spheres to produce the originally expected surface structure on the spheres. After the application of this new procedure the use of x-ray reflectometry directly at the spheres will be possible. It is expected to reduce the uncertainty contribution due to the SL down to 1 × 10-8.

  15. Construction and surface/interface behavior of bio-functional surface layer by microwave-excited Ar/H2O plasma-induced polyethylene glycol polymerization

    Science.gov (United States)

    Shao, Z.; Ogino, A.; Nagatsu, M.

    2017-07-01

    Ar/H2O microwave-excited surface-wave plasma-induced grafting-polymerization and crosslinking technique was presented to construct a bio-functional surface layer. Optical emission spectroscopy was used to diagnose Ar/H2O plasma. The surface/interface behavior especially the aging effect of hydroxyl groups over the grafted PEG spacer layer was investigated by measuring water contact angle and X-ray photoelectron spectroscopy. The results demonstrate that the addition of water vapor into Ar plasma can optimize the concentration of hydroxyl functional groups on surface; grafted PEG spacer layer can provide a long-term hydrophilicity of PU films, and alleviate the aging effect of hydroxyl functional groups.

  16. Observational constraints on Arctic boundary-layer clouds, surface moisture and sensible heat fluxes

    Science.gov (United States)

    Wu, D. L.; Boisvert, L.; Klaus, D.; Dethloff, K.; Ganeshan, M.

    2016-12-01

    The dry, cold environment and dynamic surface variations make the Arctic a unique but difficult region for observations, especially in the atmospheric boundary layer (ABL). Spaceborne platforms have been the key vantage point to capture basin-scale changes during the recent Arctic warming. Using the AIRS temperature, moisture and surface data, we found that the Arctic surface moisture flux (SMF) had increased by 7% during 2003-2013 (18 W/m2 equivalent in latent heat), mostly in spring and fall near the Arctic coastal seas where large sea ice reduction and sea surface temperature (SST) increase were observed. The increase in Arctic SMF correlated well with the increases in total atmospheric column water vapor and low-level clouds, when compared to CALIPSO cloud observations. It has been challenging for climate models to reliably determine Arctic cloud radiative forcing (CRF). Using the regional climate model HIRHAM5 and assuming a more efficient Bergeron-Findeisen process with generalized subgrid-scale variability for total water content, we were able to produce a cloud distribution that is more consistent with the CloudSat/CALIPSO observations. More importantly, the modified schemes decrease (increase) the cloud water (ice) content in mixed-phase clouds, which help to improve the modeled CRF and energy budget at the surface, because of the dominant role of the liquid water in CRF. Yet, the coupling between Arctic low clouds and the surface is complex and has strong impacts on ABL. Studying GPS/COSMIC radio occultation (RO) refractivity profiles in the Arctic coldest and driest months, we successfully derived ABL inversion height and surface-based inversion (SBI) frequency, and they were anti-correlated over the Arctic Ocean. For the late summer and early fall season, we further analyzed Japanese R/V Mirai ship measurements and found that the open-ocean surface sensible heat flux (SSHF) can explain 10 % of the ABL height variability, whereas mechanisms such as cloud

  17. Surfactant-Associated Bacteria in the Near Surface Layer of the Ocean

    Science.gov (United States)

    Kurata, Naoko; Vella, Katie; Soloviev, Alexander; Matt, Silvia; Tartar, Aurelien; Shivji, Mahmood; Perrie, William

    2013-04-01

    It has recently been realized that biogeochemical processes in the ocean are, to a large extent, the result of nanoscale processes in the microbial part of the pelagic food web. Bacteria found in thin near-surface layers of the ocean - bacterioneuston - are of special interest due to a number of practical applications, including air-sea gas exchange, production of climate-active marine aerosols and remote sensing of the ocean. In particular, bacteria involved in the production of the surface active materials resulting in slicks on the sea surface can potentially be observed from space using high-resolution remote sensing techniques. In this work done by a multidisciplinary team, we demonstrate a direct connection between surfactant-associated bacteria, identified with an advanced DNA analysis, and fine-scale features on the sea surface in synthetic aperture radar (SAR) imagery. Experiments were conducted in the Straits of Florida during RASRASAT 2 satellite overpasses. The sea surface microlayer sampling method was designed to enable aseptic bacterial sampling. A 47 mm polycarbonate membrane was utilized at each sampling site to obtain a snapshot of the bacteria community structure at a specific space and time. Microbial composition was determined using DNA analysis of 16S rRNA genes. A new generation high-throughput sequencing method (454) was employed to compensate for the small sample size. A total of 27,006 nucleotide sequences with an average 437.8 bp in length were analyzed. From in situ samples taken during satellite overpasses, we found a higher abundance of surfactant-associated bacteria in slick (visible in SAR from space) as compared to non-slick areas; furthermore, higher abundance of this type of bacteria was observed in subsurface samples than in those taken from the sea surface. These observations suggest that surfactants are produced by marine bacteria mostly in the water column and migrate up to the sea surface by diffusion, air bubbles, or

  18. Rendering of surface-geometries at job-generation level for camouflaging the layered nature of Additively Manufactured parts

    DEFF Research Database (Denmark)

    Pedersen, D. B.; Hansen, H. N.; Nielsen, J. S.

    2014-01-01

    ] It is proposed to camouflage these layers in order to produce parts with a better visual appeal, and to add functional surface structures. In order to generate such surface structures without adding a challenging computational overhead at job-generation, inspiration from Computer Generated Imaging (CGI) is found...

  19. Performance Assessment of New Land-Surface and Planetary Boundary Layer Physics in the WRF-ARW

    Science.gov (United States)

    The Pleim-Xiu land surface model, Pleim surface layer scheme, and Asymmetric Convective Model (version 2) are now options in version 3.0 of the Weather Research and Forecasting model (WRF) Advanced Research WRF (ARW) core. These physics parameterizations were developed for the f...

  20. Surface passivation of nano-textured fluorescent SiC by atomic layer deposited TiO2

    DEFF Research Database (Denmark)

    Lu, Weifang; Ou, Yiyu; Jokubavicius, Valdas

    2016-01-01

    Nano-textured surfaces have played a key role in optoelectronic materials to enhance the light extraction efficiency. In this work, morphology and optical properties of nano-textured SiC covered with atomic layer deposited (ALD) TiO2 were investigated. In order to obtain a high quality surface...