WorldWideScience

Sample records for surface layer comprises

  1. Method of forming a nanocluster comprising dielectric layer and device comprising such a layer

    NARCIS (Netherlands)

    2009-01-01

    A method of forming a dielectric layer (330) on a further layer (114, 320) of a semiconductor device (300) is disclosed. The method comprises depositing a dielectric precursor compound and a further precursor compound over the further layer (114, 320), the dielectric precursor compound comprising a

  2. Photovoltaic device comprising compositionally graded intrinsic photoactive layer

    Science.gov (United States)

    Hoffbauer, Mark A; Williamson, Todd L

    2013-04-30

    Photovoltaic devices and methods of making photovoltaic devices comprising at least one compositionally graded photoactive layer, said method comprising providing a substrate; growing onto the substrate a uniform intrinsic photoactive layer having one surface disposed upon the substrate and an opposing second surface, said intrinsic photoactive layer consisting essentially of In.sub.1-xA.sub.xN,; wherein: i. 0.ltoreq.x.ltoreq.1; ii. A is gallium, aluminum, or combinations thereof; and iii. x is at least 0 on one surface of the intrinsic photoactive layer and is compositionally graded throughout the layer to reach a value of 1 or less on the opposing second surface of the layer; wherein said intrinsic photoactive layer is isothermally grown by means of energetic neutral atom beam lithography and epitaxy at a temperature of 600.degree. C. or less using neutral nitrogen atoms having a kinetic energy of from about 1.0 eV to about 5.0 eV, and wherein the intrinsic photoactive layer is grown at a rate of from about 5 nm/min to about 100 nm/min.

  3. Modeling superhydrophobic surfaces comprised of random roughness

    Science.gov (United States)

    Samaha, M. A.; Tafreshi, H. Vahedi; Gad-El-Hak, M.

    2011-11-01

    We model the performance of superhydrophobic surfaces comprised of randomly distributed roughness that resembles natural surfaces, or those produced via random deposition of hydrophobic particles. Such a fabrication method is far less expensive than ordered-microstructured fabrication. The present numerical simulations are aimed at improving our understanding of the drag reduction effect and the stability of the air-water interface in terms of the microstructure parameters. For comparison and validation, we have also simulated the flow over superhydrophobic surfaces made up of aligned or staggered microposts for channel flows as well as streamwise or spanwise ridge configurations for pipe flows. The present results are compared with other theoretical and experimental studies. The numerical simulations indicate that the random distribution of surface roughness has a favorable effect on drag reduction, as long as the gas fraction is kept the same. The stability of the meniscus, however, is strongly influenced by the average spacing between the roughness peaks, which needs to be carefully examined before a surface can be recommended for fabrication. Financial support from DARPA, contract number W91CRB-10-1-0003, is acknowledged.

  4. Anti corrosion layer for stainless steel in molten carbonate fuel cell - comprises phase vapour deposition of titanium nitride, aluminium nitride or chromium nitride layer then oxidising layer in molten carbonate electrolyte

    DEFF Research Database (Denmark)

    2000-01-01

    Forming an anticorrosion protective layer on a stainless steel surface used in a molten carbonate fuel cell (MCFC) - comprises the phase vapour deposition (PVD) of a layer comprising at least one of titanium nitride, aluminium nitride or chromium nitride and then forming a protective layer in situ...

  5. Polymer coating comprising 2-methoxyethyl acrylate units synthesized by surface-initiated atom transfer radical polymerization

    DEFF Research Database (Denmark)

    2011-01-01

    Source: US2012184029A The present invention relates to preparation of a polymer coating comprising or consisting of polymer chains comprising or consisting of units of 2-methoxyethyl acrylate synthesized by Surface-Initiated Atom Transfer Radical Polymerization (SI ATRP) such as ARGET SI ATRP...

  6. High-performance organic light-emitting diodes comprising ultrastable glass layers

    Science.gov (United States)

    Rodríguez-Viejo, Javier

    2018-01-01

    Organic light-emitting diodes (OLEDs) are one of the key solid-state light sources for various applications including small and large displays, automotive lighting, solid-state lighting, and signage. For any given commercial application, OLEDs need to perform at their best, which is judged by their device efficiency and operational stability. We present OLEDs that comprise functional layers fabricated as ultrastable glasses, which represent the thermodynamically most favorable and, thus, stable molecular conformation achievable nowadays in disordered solids. For both external quantum efficiencies and LT70 lifetimes, OLEDs with four different phosphorescent emitters show >15% enhancements over their respective reference devices. The only difference to the latter is the growth condition used for ultrastable glass layers that is optimal at about 85% of the materials’ glass transition temperature. These improvements are achieved through neither material refinements nor device architecture optimization, suggesting a general applicability of this concept to maximize the OLED performance, no matter which specific materials are used. PMID:29806029

  7. Solute transport in a single fracture involving an arbitrary length decay chain with rock matrix comprising different geological layers.

    Science.gov (United States)

    Mahmoudzadeh, Batoul; Liu, Longcheng; Moreno, Luis; Neretnieks, Ivars

    2014-08-01

    A model is developed to describe solute transport and retention in fractured rocks. It accounts for advection along the fracture, molecular diffusion from the fracture to the rock matrix composed of several geological layers, adsorption on the fracture surface, adsorption in the rock matrix layers and radioactive decay-chains. The analytical solution, obtained for the Laplace-transformed concentration at the outlet of the flowing channel, can conveniently be transformed back to the time domain by the use of the de Hoog algorithm. This allows one to readily include it into a fracture network model or a channel network model to predict nuclide transport through channels in heterogeneous fractured media consisting of an arbitrary number of rock units with piecewise constant properties. More importantly, the simulations made in this study recommend that it is necessary to account for decay-chains and also rock matrix comprising at least two different geological layers, if justified, in safety and performance assessment of the repositories for spent nuclear fuel. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Characteristics of magnetic tunnel junctions comprising ferromagnetic amorphous NiFeSiB layers

    International Nuclear Information System (INIS)

    Chun, B.S.; Kim, Y.K.; Hwang, J.Y.; Yim, H.I.; Rhee, J.R.; Kim, T.W.

    2007-01-01

    Magnetic tunnel junctions (MTJs), which consisted of amorphous ferromagnetic Ni 16 Fe 62 Si 8 B 14 free layers, were investigated. NiFeSiB has a lower saturation magnetization (M s : 800 emu/cm 3 ) than Co 90 Fe 10 and a higher anisotropy constant (K u : 2700 erg/cm 3 ) than Ni 80 Fe 20 . By increasing the free layer thickness, the tunnel magnetoresistance (TMR) ratio of up to 41% was achieved and it exhibited a much lower switching field (H sw ) than the conventionally used CoFe free layer MTJ. Furthermore, by inserting a thin CoFe layer (1 nm) at the tunnel barrier/NiFeSiB interface, the TMR ratio and switching squareness were enhanced

  9. Modeling drag reduction and meniscus stability of superhydrophobic surfaces comprised of random roughness

    Science.gov (United States)

    Samaha, Mohamed A.; Tafreshi, Hooman Vahedi; Gad-el-Hak, Mohamed

    2011-01-01

    Previous studies dedicated to modeling drag reduction and stability of the air-water interface on superhydrophobic surfaces were conducted for microfabricated coatings produced by placing hydrophobic microposts/microridges arranged on a flat surface in aligned or staggered configurations. In this paper, we model the performance of superhydrophobic surfaces comprised of randomly distributed roughness (e.g., particles or microposts) that resembles natural superhydrophobic surfaces, or those produced via random deposition of hydrophobic particles. Such fabrication method is far less expensive than microfabrication, making the technology more practical for large submerged bodies such as submarines and ships. The present numerical simulations are aimed at improving our understanding of the drag reduction effect and the stability of the air-water interface in terms of the microstructure parameters. For comparison and validation, we have also simulated the flow over superhydrophobic surfaces made up of aligned or staggered microposts for channel flows as well as streamwise or spanwise ridges configurations for pipe flows. The present results are compared with theoretical and experimental studies reported in the literature. In particular, our simulation results are compared with work of Sbragaglia and Prosperetti, and good agreement has been observed for gas fractions up to about 0.9. The numerical simulations indicate that the random distribution of surface roughness has a favorable effect on drag reduction, as long as the gas fraction is kept the same. This effect peaks at about 30% as the gas fraction increases to 0.98. The stability of the meniscus, however, is strongly influenced by the average spacing between the roughness peaks, which needs to be carefully examined before a surface can be recommended for fabrication. It was found that at a given maximum allowable pressure, surfaces with random post distribution produce less drag reduction than those made up of

  10. Laser modification of macroscopic properties of metal surface layer

    Science.gov (United States)

    Kostrubiec, Franciszek

    1995-03-01

    Surface laser treatment of metals comprises a number of diversified technological operations out of which the following can be considered the most common: oxidation and rendering surfaces amorphous, surface hardening of steel, modification of selected physical properties of metal surface layers. In the paper basic results of laser treatment of a group of metals used as base materials for electric contacts have been presented. The aim of the study was to test the usability of laser treatment from the viewpoint of requirements imposed on materials for electric contacts. The results presented in the paper refer to two different surface treatment technologies: (1) modification of infusible metal surface layer: tungsten and molybdenum through laser fusing of their surface layer and its crystallization, and (2) modification of surface layer properties of other metals through laser doping of their surface layer with foreign elements. In the paper a number of results of experimental investigations obtained by the team under the author's supervision are presented.

  11. Apparatus for plasma surface treating and preparation of membrane layers

    NARCIS (Netherlands)

    1990-01-01

    An apparatus suitable for plasma surface treating (e.g., forming a membrane layer on a substrate surface) comprises a plasma generation section which is operable at least at substantially atmospheric pressure and is in communication via at least one plasma inlet (e.g., a nozzle) with an enclosed

  12. 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.

  13. Method for plasma surface treating and preparation of membrane layers

    NARCIS (Netherlands)

    1992-01-01

    The invention relates to an apparatus suitable for plasma surface treating (e.g. forming a membrane layer on a substrate) which comprises a plasma generation section (2) which is in communication via at least one plasma inlet means (4) (e.g. a nozzle) with an enclosed plasma treating section (3)

  14. Molecularly oriented surface relief formation in polymethacrylates comprising N-benzylideneaniline derivative side groups

    Science.gov (United States)

    Kawatsuki, Nobuhiro; Hosoda, Risa; Kondo, Mizuho; Sasaki, Tomoyuki; Ono, Hiroshi

    2014-12-01

    Molecularly oriented surface relief (SR) formation in polymethacrylates with N-benzylideneaniline (NBA) derivative side groups is investigated by holographic exposure using a 325 nm He-Cd laser. Because the NBA moieties show a photoinduced orientation perpendicular to the polarization of light, polarization holography successfully forms a molecularly oriented SR structure in accordance with the polarization distribution that includes p-polarized components. Although intensity holography induces molecular orientation, it does not generate a satisfactory SR structure. In all the holographic modes, the SR depth depends on the direction of the C=N bonds in the NBA moieties and the photoproducts affect the SR formation ability.

  15. 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

  16. Bias voltage dependence of magnetic tunnel junctions comprising amorphous ferromagnetic CoFeSiB layer with double barriers

    International Nuclear Information System (INIS)

    Yim, H.I.; Lee, S.Y.; Hwang, J.Y.; Rhee, J.R.; Chun, B.S.; Wang, K.L.; Kim, Y.K.; Kim, T.W.; Lee, S.S.; Hwang, D.G.

    2008-01-01

    Double-barrier magnetic tunnel junctions (DMTJs) with and without an amorphous ferromagnetic material such as CoFeSiB 10, CoFe 5/CoFeSiB 5, and CoFe 10 (nm) were prepared and compared to investigate the bias voltage dependence of the tunneling magnetoresistance (TMR) ratio. Typical DMTJ structures were Ta 45/Ru 9.5/IrMn 10/CoFe 7/AlO x /free layer 10/AlO x /CoFe 7/IrMn 10/Ru 60 (in nanometers). The interlayer coupling field and the normalized TMR ratios at the applied voltages of +0.4 and -0.4 V of the amorphous CoFeSiB free-layer DMTJ offer lower and higher values than that of the polycrystalline CoFe free-layer DMTJ, respectively. An amorphous ferromagnetic CoFeSiB layer improves the interface roughness of the free layer/tunnel barrier and, as a result, the interlayer coupling field and bias voltage dependence of the TMR ratio are suppressed at a given voltage. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. 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

  18. 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

  19. 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.

  20. An experimental study on the preparation of tochilinite-originated intercalation compounds comprised of Fe 1-xS host layers and various kinds of guest layers

    Science.gov (United States)

    Peng, Yiya; Xi, Guangcheng; Zhong, Chang; Wang, Linping; Lu, Jun; Sun, Ximeng; Zhu, Lu; Han, Qikun; Chen, Lin; Shi, Lei; Sun, Mei; Li, Qianrong; Yu, Min; Yin, Mingwen

    2009-08-01

    Tochilinite represents a mineral group of ordered mixed-layer structures containing alternating Fe 1-xS layers with mackinawite-like structure and metal hydroxide layers with Mg(OH) 2-like structure. In this article, we report the preparation of a series of tochilinite-originated (or Fe 1-xS-based) intercalation compounds (ICs). According to their preparation procedures, these ICs can be divided into four kinds. The first kind of IC was sodium tochilinite (Na-tochilinite), which was prepared by the hydrothermal reaction of metallic Fe particles with concentrated Na 2S·9H 2O aqueous solutions. The hydroxide layer of the Na-tochilinite was a mixed hydroxide of Na + ions along with a certain amount of Fe 2+ ions. When the hydroxide layer of the Na-tochilinite completely dissolved in aqueous solutions, a Fe-deficient mackinawite-like phase Fe 1-xS was obtained, which was probably an electron-deficient p-type conductor. The second kind of ICs was prepared by 'low-temperature direct intercalation in aqueous solutions, using Na-tochilinite as a parental precursor. When the Na-tochilinite was ultrasonicated in aqueous solutions containing Lewis basic complexing agents (like NH 3, N 2H 4, 2,2'-bipyridine (bipy), and 1,10-phenanthroline (phen)), the Na + ions of the Na-tochilinite were removed and the Lewis basic complexing agents entered the hydroxide layer of the Na-tochilinite and became coordinated with the Fe 2+ ions, and the second kind of ICs was thus produced. The second kind of ICs includes NH 3 IC, N 2H 4 IC, N 2H 4-NH 3 IC, [Fe(bipy) 3] 2+-containing IC and [Fe(phen) 3] 2+-containing IC. The third kind of ICs, which includes NH 3 IC, N 2H 4-NH 3 IC and N 2H 4-LiOH (NaOH) IC, was prepared by the hydrothermal reaction of metallic Fe particles with (NH 4) 2S aqueous solution, S (elemental) + N 2H 4·H 2O aqueous solution, and S + N 2H 4·H 2O + LiOH (NaOH) aqueous solution, respectively. The third kind of ICs has a close relationship with the second kind of ICs both

  1. Surface rheology of saponin adsorption layers.

    Science.gov (United States)

    Stanimirova, R; Marinova, K; Tcholakova, S; Denkov, N D; Stoyanov, S; Pelan, E

    2011-10-18

    Extracts of the Quillaja saponaria tree contain natural surfactant molecules called saponins that very efficiently stabilize foams and emulsions. Therefore, such extracts are widely used in several technologies. In addition, saponins have demonstrated nontrivial bioactivity and are currently used as essential ingredients in vaccines, food supplements, and other health products. Previous preliminary studies showed that saponins have some peculiar surface properties, such as a very high surface modulus, that may have an important impact on the mechanisms of foam and emulsion stabilization. Here we present a detailed characterization of the main surface properties of highly purified aqueous extracts of Quillaja saponins. Surface tension isotherms showed that the purified Quillaja saponins behave as nonionic surfactants with a relatively high cmc (0.025 wt %). The saponin adsorption isotherm is described well by the Volmer equation, with an area per molecule of close to 1 nm(2). By comparing this area to the molecular dimensions, we deduce that the hydrophobic triterpenoid rings of the saponin molecules lie parallel to the air-water interface, with the hydrophilic glucoside tails protruding into the aqueous phase. Upon small deformation, the saponin adsorption layers exhibit a very high surface dilatational elasticity (280 ± 30 mN/m), a much lower shear elasticity (26 ± 15 mN/m), and a negligible true dilatational surface viscosity. The measured dilatational elasticity is in very good agreement with the theoretical predictions of the Volmer adsorption model (260 mN/m). The measured characteristic adsorption time of the saponin molecules is 4 to 5 orders of magnitude longer than that predicted theoretically for diffusion-controlled adsorption, which means that the saponin adsorption is barrier-controlled around and above the cmc. The perturbed saponin layers relax toward equilibrium in a complex manner, with several relaxation times, the longest of them being around 3

  2. Are atmospheric surface layer flows ergodic?

    Science.gov (United States)

    Higgins, Chad W.; Katul, Gabriel G.; Froidevaux, Martin; Simeonov, Valentin; Parlange, Marc B.

    2013-06-01

    The transposition of atmospheric turbulence statistics from the time domain, as conventionally sampled in field experiments, is explained by the so-called ergodic hypothesis. In micrometeorology, this hypothesis assumes that the time average of a measured flow variable represents an ensemble of independent realizations from similar meteorological states and boundary conditions. That is, the averaging duration must be sufficiently long to include a large number of independent realizations of the sampled flow variable so as to represent the ensemble. While the validity of the ergodic hypothesis for turbulence has been confirmed in laboratory experiments, and numerical simulations for idealized conditions, evidence for its validity in the atmospheric surface layer (ASL), especially for nonideal conditions, continues to defy experimental efforts. There is some urgency to make progress on this problem given the proliferation of tall tower scalar concentration networks aimed at constraining climate models yet are impacted by nonideal conditions at the land surface. Recent advancements in water vapor concentration lidar measurements that simultaneously sample spatial and temporal series in the ASL are used to investigate the validity of the ergodic hypothesis for the first time. It is shown that ergodicity is valid in a strict sense above uniform surfaces away from abrupt surface transitions. Surprisingly, ergodicity may be used to infer the ensemble concentration statistics of a composite grass-lake system using only water vapor concentration measurements collected above the sharp transition delineating the lake from the grass surface.

  3. Surface layer temperature inversion in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Pankajakshan, T.; Gopalakrishna, V.V.; Muraleedharan, P.M.; Reddy, G.V.; Araligidad, N.; Shenoy, Shrikant

    Surface layer temperature inversion occurring in the Bay of Bengal has been addressed. Hydrographic data archived in the Indian Oceanographic Data Center are used to understand various aspects of the temperature inversion of surface layer in the Bay...

  4. Turbulent transport in the atmospheric surface layer

    International Nuclear Information System (INIS)

    Tagesson, Torbern

    2012-04-01

    In the modelling of transport and accumulation of the radioactive isotope carbon-14 (C-14) in the case of a potential release from a future repository of radioactive waste, it is important to describe the transport of the isotope in the atmosphere. This report aims to describe the turbulent transport within the lower part of the atmosphere; the inertial surface layer and the roughness sublayer. Transport in the inertial surface layer is dependent on several factors, whereof some can be neglected under certain circumstances. Under steady state conditions, fully developed turbulent conditions, in flat and horizontal homogeneous areas, it is possible to apply an eddy diffusivity approach for estimating vertical transport of C. The eddy diffusivity model assumes that there is proportionality between the vertical gradient and the transport of C. The eddy diffusivity is depending on the atmospheric turbulence, which is affected by the interaction between mean wind and friction of the ground surface and of the sensible heat flux in the atmosphere. In this report, it is described how eddy diffusivity of the inertial surface layer can be estimated from 3-d wind measurements and measurements of sensible heat fluxes. It is also described how to estimate the eddy diffusivity in the inertial surface layer from profile measurements of temperature and wind speed. Close to the canopy, wind and C profiles are influenced by effects of the surface roughness; this section of the atmosphere is called the roughness sublayer. Its height is up to ∼3 times the height of the plant canopy. When the mean wind interacts with the canopy, turbulence is not only produced by shear stress and buoyancy, it is additionally created by wakes, which are formed behind the plants. Turbulence is higher than it would be over a flat surface, and the turbulent transport is hereby more efficient. Above the plant canopy, but still within the roughness sublayer, a function that compensates for the effect of

  5. Turbulent transport in the atmospheric surface layer

    Energy Technology Data Exchange (ETDEWEB)

    Tagesson, Torbern [Dept. of Physical Geography and Ecosystem Science, Lund Univ., Lund (Sweden)

    2012-04-15

    In the modelling of transport and accumulation of the radioactive isotope carbon-14 (C-14) in the case of a potential release from a future repository of radioactive waste, it is important to describe the transport of the isotope in the atmosphere. This report aims to describe the turbulent transport within the lower part of the atmosphere; the inertial surface layer and the roughness sublayer. Transport in the inertial surface layer is dependent on several factors, whereof some can be neglected under certain circumstances. Under steady state conditions, fully developed turbulent conditions, in flat and horizontal homogeneous areas, it is possible to apply an eddy diffusivity approach for estimating vertical transport of C. The eddy diffusivity model assumes that there is proportionality between the vertical gradient and the transport of C. The eddy diffusivity is depending on the atmospheric turbulence, which is affected by the interaction between mean wind and friction of the ground surface and of the sensible heat flux in the atmosphere. In this report, it is described how eddy diffusivity of the inertial surface layer can be estimated from 3-d wind measurements and measurements of sensible heat fluxes. It is also described how to estimate the eddy diffusivity in the inertial surface layer from profile measurements of temperature and wind speed. Close to the canopy, wind and C profiles are influenced by effects of the surface roughness; this section of the atmosphere is called the roughness sublayer. Its height is up to {approx}3 times the height of the plant canopy. When the mean wind interacts with the canopy, turbulence is not only produced by shear stress and buoyancy, it is additionally created by wakes, which are formed behind the plants. Turbulence is higher than it would be over a flat surface, and the turbulent transport is hereby more efficient. Above the plant canopy, but still within the roughness sublayer, a function that compensates for the effect

  6. Preparation of electrodes on cfrp composites with low contact resistance comprising laser-based surface pre-treatment

    KAUST Repository

    Almuhammadi, Khaled Hamdan

    2016-12-29

    Various examples are provided related to the preparation of electrodes on carbon fiber reinforced polymer (CFRP) composites with low contact resistance. Laser-based surface preparation can be used for bonding to CFRP composites. In one example, a method includes preparing a pretreated target area on a CFRP composite surface using laser pulsed irradiation and bonding an electrode to exposed fibers in the pretreated target area. The surface preparation can allow the electrode to have a low contact resistance with the CFRP composite.

  7. 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).

  8. 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

  9. Preparation of electrodes on cfrp composites with low contact resistance comprising laser-based surface pre-treatment

    KAUST Repository

    Almuhammadi, Khaled Hamdan; Lubineau, Gilles; Alfano, Marco Francesco; Buttner, Ulrich

    2016-01-01

    Various examples are provided related to the preparation of electrodes on carbon fiber reinforced polymer (CFRP) composites with low contact resistance. Laser-based surface preparation can be used for bonding to CFRP composites. In one example, a

  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. Moored surface buoy observations of the diurnal warm layer

    KAUST Repository

    Prytherch, J.; Farrar, J. T.; Weller, R. A.

    2013-01-01

    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.

  12. 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.

  13. 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

  14. Avoiding unstable regions in the design space of EUV mirror systems comprising high-order aspheric surfaces

    NARCIS (Netherlands)

    Marinescu, O.; Bociort, F.; Braat, J.

    2004-01-01

    When Extreme Ultraviolet mirror systems having several high-order aspheric surfaces are optimized, the configurations often enter into highly unstable regions of the parameter space. Small changes of system parameters lead then to large changes in ray paths, and therefore optimization algorithms

  15. Apparatus suitable for plasma surface treating and process for preparing membrane layers

    NARCIS (Netherlands)

    1988-01-01

    The invention relates to an apparatus suitable for plasma surface treating (e.g. forming a membrane layer on a substrate) which comprises a plasma generation section (2) which is in communication via at least one plasma inlet means (4) (e.g. a nozzle) with an enclosed plasma treating section (3)

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

    Science.gov (United States)

    2015-10-01

    hydrostatic equation: dP dz = −ρa g −→ ∫ ZI 0 ρa dz = − 1 g ∫ dP = + 1 g [P (0)− P (ZI)]. (6.14) The pressure at the surface is... surface pressure is estimated, we can compute a vertical pressure profile using the hydrostatic equation and a selected temperature profile based on dP... surface -layer atmosphere. By surface layer what is intended is a layer of foliage plus the surface itself. That is, a flat ground surface that

  17. Electrical properties of GaAs metal–oxide–semiconductor structure comprising Al2O3 gate oxide and AlN passivation layer fabricated in situ using a metal–organic vapor deposition/atomic layer deposition hybrid system

    Directory of Open Access Journals (Sweden)

    Takeshi Aoki

    2015-08-01

    Full Text Available This paper presents a compressive study on the fabrication and optimization of GaAs metal–oxide–semiconductor (MOS structures comprising a Al2O3 gate oxide, deposited via atomic layer deposition (ALD, with an AlN interfacial passivation layer prepared in situ via metal–organic chemical vapor deposition (MOCVD. The established protocol afforded self-limiting growth of Al2O3 in the atmospheric MOCVD reactor. Consequently, this enabled successive growth of MOCVD-formed AlN and ALD-formed Al2O3 layers on the GaAs substrate. The effects of AlN thickness, post-deposition anneal (PDA conditions, and crystal orientation of the GaAs substrate on the electrical properties of the resulting MOS capacitors were investigated. Thin AlN passivation layers afforded incorporation of optimum amounts of nitrogen, leading to good capacitance–voltage (C–V characteristics with reduced frequency dispersion. In contrast, excessively thick AlN passivation layers degraded the interface, thereby increasing the interfacial density of states (Dit near the midgap and reducing the conduction band offset. To further improve the interface with the thin AlN passivation layers, the PDA conditions were optimized. Using wet nitrogen at 600 °C was effective to reduce Dit to below 2 × 1012 cm−2 eV−1. Using a (111A substrate was also effective in reducing the frequency dispersion of accumulation capacitance, thus suggesting the suppression of traps in GaAs located near the dielectric/GaAs interface. The current findings suggest that using an atmosphere ALD process with in situ AlN passivation using the current MOCVD system could be an efficient solution to improving GaAs MOS interfaces.

  18. Electron tunneling in tantalum surface layers on niobium

    International Nuclear Information System (INIS)

    Ruggiero, S.T.; Track, E.K.; Prober, D.E.; Arnold, G.B.; DeWeert, M.J.

    1986-01-01

    We have performed electron tunneling measurements on tantalum surface layers on niobium. The tunnel junctions comprise 2000-A-circle Nb base electrodes with 10--100-A-circle in situ--deposited Ta overlayers, an oxide barrier, and Ag, Pb, or Pb-Bi alloy counterelectrodes. The base electrodes were prepared by ion-beam sputter deposition. The characteristics of these junctions have been studied as a function of Ta-layer thickness. These include the critical current, bound-state energy, phonon structure, and oxide barrier shape. We have compared our results for the product I/sub c/R versus tantalum-layer thickness with an extended version of the Gallagher theory which accounts for both the finite mean free path in the Ta overlayers and suppression of the I/sub c/R product due to strong-coupling effects. Excellent fits to the data yield a value of the intrinsic scattering probability for electrons at the Ta/Nb interface of r 2 = 0.01. This is consistent with the value expected from simple scattering off the potential step created by the difference between the Fermi energies of Ta and Nb. We have found a universal empirical correlation in average barrier height phi-bar and width s in the form phi-bar = 6 eV/(s-10 A-circle) for measured junctions which holds both for our data and results for available data in the literature for oxide-barrier junctions. The latter are composed of a wide variety of base and counterelectrode materials. These results are discussed in the general context of oxide growth and compared with results for artificial tunnel barriers

  19. A novel carbohydrate-binding surface layer protein from the hyperthermophilic archaeon Pyrococcus horikoshii.

    Science.gov (United States)

    Goda, Shuichiro; Koga, Tomoyuki; Yamashita, Kenichiro; Kuriura, Ryo; Ueda, Toshifumi

    2018-04-08

    In Archaea and Bacteria, surface layer (S-layer) proteins form the cell envelope and are involved in cell protection. In the present study, a putative S-layer protein was purified from the crude extract of Pyrococcus horikoshii using affinity chromatography. The S-layer gene was cloned and expressed in Escherichia coli. Isothermal titration calorimetry analyses showed that the S-layer protein bound N-acetylglucosamine and induced agglutination of the gram-positive bacterium Micrococcus lysodeikticus. The protein comprised a 21-mer structure, with a molecular mass of 1,340 kDa, as determined using small-angle X-ray scattering. This protein showed high thermal stability, with a midpoint of thermal denaturation of 79 °C in dynamic light scattering experiments. This is the first description of the carbohydrate-binding archaeal S-layer protein and its characteristics.

  20. 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

  1. 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.

  2. 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.

  3. 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...... numerical results from higher-order closure models, it is found that, even at a downwind distance such that the internal boundary layer has grown to the full height of the planetary boundary layers, the surface stress still considerably exceeds the equilibrium value...

  4. A rational method for developing and testing stable flexible indium- and vacuum-free multilayer tandem polymer solar cells comprising up to twelve roll processed layers

    DEFF Research Database (Denmark)

    Andersen, Thomas Rieks; Dam, Henrik Friis; Andreasen, Birgitta

    2014-01-01

    and to efficiently identify layers and interfaces that are not robust we developed a double sided illumination method and demonstrate how layer thicknesses can be optimized with respect to the roll processing in the aim of achieving functional tandem devices. The devices were prepared directly on barrier foil...

  5. Characterization and use of crystalline bacterial cell surface layers

    Science.gov (United States)

    Sleytr, Uwe B.; Sára, Margit; Pum, Dietmar; Schuster, Bernhard

    2001-10-01

    Crystalline bacterial cell surface layers (S-layers) are one of the most common outermost cell envelope components of prokaryotic organisms (archaea and bacteria). S-layers are monomolecular arrays composed of a single protein or glycoprotein species and represent the simplest biological membranes developed during evolution. S-layers as the most abundant of prokaryotic cellular proteins are appealing model systems for studying the structure, synthesis, genetics, assembly and function of proteinaceous supramolecular structures. The wealth of information existing on the general principle of S-layers have revealed a broad application potential. The most relevant features exploited in applied S-layer research are: (i) pores passing through S-layers show identical size and morphology and are in the range of ultrafiltration membranes; (ii) functional groups on the surface and in the pores are aligned in well-defined positions and orientations and accessible for chemical modifications and binding functional molecules in very precise fashion; (iii) isolated S-layer subunits from a variety of organisms are capable of recrystallizing as closed monolayers onto solid supports (e.g., metals, polymers, silicon wafers) at the air-water interface, on lipid films or onto the surface of liposomes; (iv) functional domains can be incorporated in S-layer proteins by genetic engineering. Thus, S-layer technologies particularly provide new approaches for biotechnology, biomimetics, molecular nanotechnology, nanopatterning of surfaces and formation of ordered arrays of metal clusters or nanoparticles as required for nanoelectronics.

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

    African Journals Online (AJOL)

    Measurement of grassland evaporation using a surface-layer scintillometer. ... Water SA. Journal Home · ABOUT THIS JOURNAL · Advanced Search ... of soil heat flux and net irradiance, evaporation rates were calculated as a residual of the ...

  7. 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

  8. Bimetallic alloy electrocatalysts with multilayered platinum-skin surfaces

    Science.gov (United States)

    Stamenkovic, Vojislav R.; Wang, Chao; Markovic, Nenad M.

    2016-01-26

    Compositions and methods of preparing a bimetallic alloy having enhanced electrocatalytic properties are provided. The composition comprises a PtNi substrate having a surface layer, a near-surface layer, and an inner layer, where the surface layer comprises a nickel-depleted composition, such that the surface layer comprises a platinum skin having at least one atomic layer of platinum.

  9. Impedance of Surface Footings on Layered Ground

    DEFF Research Database (Denmark)

    Andersen, Lars; Clausen, Johan Christian

    2005-01-01

    is discussed. Based on the Green's function for a stratified half-space, the impedance of a surface footing with arbitrary shape is computed. A wind turbine foundation is analysed in the frequency range 0 to 3 Hz. Analyses show that soil stratification may lead to a significant changes in the impedance related...

  10. Impedance of Surface Footings on Layered Ground

    DEFF Research Database (Denmark)

    Andersen, Lars; Clausen, Johan

    2008-01-01

    is discussed. Based on the Green's function for a stratified half-space, the impedance of a surface footing with arbitrary shape is computed. A wind turbine foundation is analysed in the frequency range 0-3 Hz. Analyses show that soil stratification may lead to significant changes in the impedance related...

  11. Generation Mechanism of Work Hardened Surface Layer in Metal Cutting

    Science.gov (United States)

    Hikiji, Rikio; Kondo, Eiji; Kawagoishi, Norio; Arai, Minoru

    Finish machining used to be carried out in grinding, but it is being replaced by cutting with very small undeformed chip thickness. In ultra precision process, the effects of the cutting conditions and the complicated factors on the machined surface integrity are the serious problems. In this research, work hardened surface layer was dealt with as an evaluation of the machined surface integrity and the effect of the mechanical factors on work hardening was investigated experimentally in orthogonal cutting. As a result, it was found that work hardened surface layer was affected not only by the shear angle varied under the cutting conditions and the thrust force of cutting resistance, but also by the thrust force acting point, the coefficient of the thrust force and the compressive stress equivalent to the bulk hardness. Furthermore, these mechanical factors acting on the depth of the work hardened surface layer were investigated with the calculation model.

  12. Formulation and evaluation of a bilayer tablet comprising of diclofenac potassium as orodispersible layer and diclofenac sodium as sustained release core

    OpenAIRE

    Abbas, Jabbar; Bashir, Sajid; Samie, Muhammad; Laghari, Sadaf

    2017-01-01

    Diclofenac a phenylacetic acid derivative has long been used as an anti-inflammatory and analgesic drug to treat certain conditions however its sustained release formulation with immediate release loading dose is desirable. The rationale of the current work was to develop and evaluate bilayer tablets with diclofenac potassium as orodispersible layer and diclofenac sodium as sustained release core. The diclofenac sodium core was prepared by wet granulation method while the...

  13. Elimination device for decontaminated surface layers

    International Nuclear Information System (INIS)

    Yoshikawa, Kozo.

    1983-01-01

    Purpose: To conduct efficient decontamination injecting solid carbon dioxide particles at a high speed by using a simple and compact device. Constitution: Liquid carbon dioxide is injected from a first vessel containing liquid carbon dioxide by way of a carbon dioxide supply tube to a solid carbon dioxide particle jetting device. The liquid carbon dioxide is partially converted into fine solid carbon dioxide particles due to the temperature reduction caused by adiabatic expansion of the gaseous carbon dioxide in an expansion space for the gaseous carbon dioxide formed in the jetting device and arrives at a solid carbon dioxide injection nozzle in communication with the expansion space. Then, the fine solid carbon dioxide particles are further cooled and accelerated by the nitrogen gas jetted out from a nitrogen gas nozzle at the top of a nitrogen gas supply tube in communication with a second vessel containing liquid nitrogen disposed within the nozzle, and jetted out from the solid carbon dioxide injection nozzle to collide against the surface to be decontaminated and eliminate the surface contamination. (Seki, T.)

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

    Indian Academy of Sciences (India)

    Administrator

    Surface reactivity and layer analysis of chemisorbed reaction films in ... in the nitrogen environment. Keywords. Surface reactivity ... sium (Na–K) compounds in the coating or core of the ..... Barkshire I R, Pruton M and Smith G C 1995 Appl. Sur.

  15. 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.

  16. Optical transparency of graphene layers grown on metal surfaces

    International Nuclear Information System (INIS)

    Rut’kov, E. V.; Lavrovskaya, N. P.; Sheshenya, E. S.; Gall, N. R.

    2017-01-01

    It is shown that, in contradiction with the fundamental results obtained for free graphene, graphene films grown on the Rh(111) surface to thicknesses from one to ~(12–15) single layers do not absorb visible electromagnetic radiation emitted from the surface and influence neither the brightness nor true temperature of the sample. At larger thicknesses, such absorption occurs. This effect is observed for the surfaces of other metals, specifically, Pt(111), Re(1010), and Ni(111) and, thus, can be considered as being universal. It is thought that the effect is due to changes in the electronic properties of thin graphene layers because of electron transfer between graphene and the metal substrate.

  17. Optical transparency of graphene layers grown on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Rut’kov, E. V. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Lavrovskaya, N. P. [State University of Aerospace Instrumentation (Russian Federation); Sheshenya, E. S., E-mail: sheshenayket@gmail.ru; Gall, N. R. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

    2017-04-15

    It is shown that, in contradiction with the fundamental results obtained for free graphene, graphene films grown on the Rh(111) surface to thicknesses from one to ~(12–15) single layers do not absorb visible electromagnetic radiation emitted from the surface and influence neither the brightness nor true temperature of the sample. At larger thicknesses, such absorption occurs. This effect is observed for the surfaces of other metals, specifically, Pt(111), Re(1010), and Ni(111) and, thus, can be considered as being universal. It is thought that the effect is due to changes in the electronic properties of thin graphene layers because of electron transfer between graphene and the metal substrate.

  18. Effects of surface modification on the critical behaviour in multiple-surface-layer ferroelectric thin films

    International Nuclear Information System (INIS)

    Lu, Z X

    2013-01-01

    Using the usual mean-field theory approximation, the critical behaviour (i.e. the Curie temperature T c and the critical surface transverse field Ω sc ) in a multiple-surface-layer ferroelectric thin film is studied on the basis of the spin- 1/2 transverse Ising model. The dependence of the Curie temperature T c on the surface transverse field Ω s and the surface layer number N s are discussed in detail. Meanwhile the dependence of the critical surface transverse field Ω sc on the surface layer number N s is also examined. The numerical results indicate that the critical behaviour of ferroelectric thin films is obviously affected by modifications of the surface transverse field Ω s and surface layer number N s .

  19. 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.

  20. 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.

  1. 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.

  2. Surface influence upon vertical profiles in the nocturnal boundary layer

    Science.gov (United States)

    Garratt, J. R.

    1983-05-01

    Near-surface wind profiles in the nocturnal boundary layer, depth h, above relatively flat, tree-covered terrain are described in the context of the analysis of Garratt (1980) for the unstable atmospheric boundary layer. The observations at two sites imply a surface-based transition layer, of depth z *, within which the observed non-dimensional profiles Φ M 0 are a modified form of the inertial sub-layer relation Φ _M ( {{z L}} = ( {{{1 + 5_Z } L}} ) according to Φ _M^{{0}} ˜eq ( {{{1 + 5z} L}} )exp [ { - 0.7( {{{1 - z} z}_ * } )] , where z is height above the zero-plane displacement and L is the Monin-Obukhov length. At both sites the depth z * is significantly smaller than the appropriate neutral value ( z * N ) found from the previous analysis, as might be expected in the presence of a buoyant sink for turbulent kinetic energy.

  3. Waveguide module comprising a first plate with a waveguide channel and a second plate with a raised portion in which a sealing layer is forced into the waveguide channel by the raised portion

    Science.gov (United States)

    Strassner, II, Bernd H.; Liedtke, Richard; McDonald, Jacob Jeremiah; Halligan, Matthew

    2018-04-17

    The various technologies presented herein relate to utilizing a sealing layer of malleable material to seal gaps, etc., at a joint between edges of a waveguide channel formed in a first plate and a surface of a clamping plate. A compression pad is included in the surface of the clamping plate and is dimensioned such that the upper surface of the pad is less than the area of the waveguide channel opening on the first plate. The sealing layer is placed between the waveguide plate and the clamping plate, and during assembly of the waveguide module, the compression pad deforms a portion of the sealing layer such that it ingresses into the waveguide channel opening. Deformation of the sealing layer results in the gaps, etc., to be filled, improving the operational integrity of the joint.

  4. 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.)

  5. 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.

  6. 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

  7. 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,

  8. 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...

  9. Wave-Breaking Turbulence in the Ocean Surface Layer

    Science.gov (United States)

    2016-06-01

    2004) used direct numerical simulation ( DNS ) to show that a single breaking wave can energize the surface layer for more than 50 wave periods, and...1941: Dissipation of energy in the locally isotropic turbulence. Dokl. Akad. Nauk SSR, 30, 301–305. Kukulka, T., and K. Brunner, 2015: Passive

  10. 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.

  11. 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.

  12. Stabilization of Leidenfrost vapour layer by textured superhydrophobic surfaces

    KAUST Repository

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

    2012-01-01

    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.

  13. 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

  14. 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...

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

    Science.gov (United States)

    2015-01-01

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

  16. Tuning plasmons layer-by-layer for quantitative colloidal sensing with surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Anderson, William J; Nowinska, Kamila; Hutter, Tanya; Mahajan, Sumeet; Fischlechner, Martin

    2018-04-19

    Surface-enhanced Raman spectroscopy (SERS) is well known for its high sensitivity that emerges due to the plasmonic enhancement of electric fields typically on gold and silver nanostructures. However, difficulties associated with the preparation of nanostructured substrates with uniform and reproducible features limit reliability and quantitation using SERS measurements. In this work we use layer-by-layer (LbL) self-assembly to incorporate multiple functional building blocks of collaborative assemblies of nanoparticles on colloidal spheres to fabricate SERS sensors. Gold nanoparticles (AuNPs) are packaged in discrete layers, effectively 'freezing nano-gaps', on spherical colloidal cores to achieve multifunctionality and reproducible sensing. Coupling between layers tunes the plasmon resonance for optimum SERS signal generation to achieve a 10 nM limit of detection. Significantly, using the layer-by-layer construction, SERS-active AuNP layers are spaced out and thus optically isolated. This uniquely allows the creation of an internal standard within each colloidal sensor to enable highly reproducible self-calibrated sensing. By using 4-mercaptobenzoic acid (4-MBA) as the internal standard adenine concentrations are quantified to an accuracy of 92.6-99.5%. Our versatile approach paves the way for rationally designed yet quantitative colloidal SERS sensors and their use in a variety of sensing applications.

  17. Amorphous surface layers in Ti-implanted Fe

    International Nuclear Information System (INIS)

    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 16 at/cm 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 17 Ti/cm 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 17 Ti/cm 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 17 Ti/cm 2 produced an amorphous layer with a lower C concentration of approx. 10 at. % and a Ti concentration of approx. 20 at. %

  18. 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.

  19. A scanning fluid dynamic gauging technique for probing surface layers

    International Nuclear Information System (INIS)

    Gordon, Patrick W; Chew, Y M John; Wilson, D Ian; Brooker, Anju D M; York, David W

    2010-01-01

    Fluid dynamic gauging (FDG) is a technique for measuring the thickness of soft solid deposit layers immersed in a liquid environment, in situ and in real time. This paper details the performance of a novel automated, scanning FDG probe (sFDG) which allows the thickness of a sample layer to be monitored at several points during an experiment, with a resolution of ±5 µm. Its application is demonstrated using layers of gelatine, polyvinyl alcohol (PVA) and baked tomato purée deposits. Swelling kinetics, as well as deformation behaviour—based on knowledge of the stresses imposed on the surface by the gauging flow—can be determined at several points, affording improved experimental data. The use of FDG as a surface scanning technique, operating as a fluid mechanical analogue of atomic force microscopy on a millimetre length scale, is also demonstrated. The measurement relies only on the flow behaviour, and is thus suitable for use in opaque fluids, does not contact the surface itself and does not rely on any specific physical properties of the surface, provided it is locally stiff

  20. 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

  1. Mechanism of protective action of surface carbide layers on titanium

    International Nuclear Information System (INIS)

    Chukalovskaya, T.V.; Chebotareva, N.P.; Tomashov, N.D.

    1990-01-01

    The protective action of surface carbide layer on titanium produced in methane atmosphere at 1000 deg C and under 6.7 kPa pressure in H 2 SO 4 solutions is studied through comparison of microsection metallographic specimens prior to and after corrosion testing (after specimen activation); through comparison of anodic characteristics after partial stripping of the layer up to its complete stripping; through analysis of the behaviour of Ti-TiC galvanic couple, and through investigation of corresponding corrosion diagrams under test conditions. It is shown that screening protective mechanism is primarily got involved in highly agressive media (high temperature and concentration of solution), and in less agressive environment the protection of titanium with carbide layer is primarily ensured by electrochemical mechanism

  2. Electrografted diazonium salt layers for antifouling on the surface of surface plasmon resonance biosensors.

    Science.gov (United States)

    Zou, Qiongjing; Kegel, Laurel L; Booksh, Karl S

    2015-02-17

    Electrografted diazonium salt layers on the surface of surface plasmon resonance (SPR) sensors present potential for a significant improvement in antifouling coatings. A pulsed potential deposition profile was used in order to circumvent mass-transport limitations for layer deposition rate. The influence of number of pulses with respect to antifouling efficacy was evaluated by nonspecific adsorption surface coverage of crude bovine serum proteins. Instead of using empirical and rough estimated values, the penetration depth and sensitivity of the SPR instrument were experimentally determined for the calculation of nonspecific adsorption surface coverage. This provides a method to better examine antifouling surface coatings and compare crossing different coatings and experimental systems. Direct comparison of antifouling performance of different diazonium salts was facilitated by a tripad SPR sensor design. The electrografted 4-phenylalanine diazonium chloride (4-APhe) layers with zwitterionic characteristic demonstrate ultralow fouling.

  3. The appearance of liquid surfaces and layers in routine radiographs

    International Nuclear Information System (INIS)

    Nilson, A.E.; Sahlgrenska Sjukhuset, Goeteborg

    1986-01-01

    As has been demonstrated, the interfaces between a gas and a body fluid or a contrast medium may be visualized in the radiographic image as various kinds of boundaries, as also may interfaces between a contrast medium and a body fluid. These can provide little diagnostic information. Data of clinical value are usually derived from boundaries that represent bounding surfaces of anatomic structures touched by the roentgen rays. In the interpretation of the radiographic image it is important to recognize whether a boundary represents an anatomic structure, a liquid surface or a diffusion layer. It is a traditional view that a liquid surface is visualized by a horizontal beam as a straight horizontal boundary and that the imaged surface is then also horizontal. As has been shown in the earlier investigations and the present one, this is not always the case, for these boundaries are usually curved with an upward concavity. It is important to bear in mind that also rays departing considerably from the horizontal may still touch the liquid surface in its meniscoid. Even a vertical beam will form a boundary when touching a meniscoid. It would also appear that the simple layering phenomenon can present difficulty in interpretation. Examples of this phenomenon that illustrate particularly important situations have been presented. Ambiguity associated with the interpretation of images produced by a vertical beam may be resolved with the aid of supplementary films exposed with a horizontal beam. (orig.)

  4. Optimized Estimation of Surface Layer Characteristics from Profiling Measurements

    Directory of Open Access Journals (Sweden)

    Doreene Kang

    2016-01-01

    Full Text Available New sampling techniques such as tethered-balloon-based measurements or small unmanned aerial vehicles are capable of providing multiple profiles of the Marine Atmospheric Surface Layer (MASL in a short time period. It is desirable to obtain surface fluxes from these measurements, especially when direct flux measurements are difficult to obtain. The profiling data is different from the traditional mean profiles obtained at two or more fixed levels in the surface layer from which surface fluxes of momentum, sensible heat, and latent heat are derived based on Monin-Obukhov Similarity Theory (MOST. This research develops an improved method to derive surface fluxes and the corresponding MASL mean profiles of wind, temperature, and humidity with a least-squares optimization method using the profiling measurements. This approach allows the use of all available independent data. We use a weighted cost function based on the framework of MOST with the cost being optimized using a quasi-Newton method. This approach was applied to seven sets of data collected from the Monterey Bay. The derived fluxes and mean profiles show reasonable results. An empirical bias analysis is conducted using 1000 synthetic datasets to evaluate the robustness of the method.

  5. 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.

  6. 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.

  7. Surface modification of upconverting nanoparticles by layer-by-layer assembled polyelectrolytes and metal ions.

    Science.gov (United States)

    Palo, Emilia; Salomäki, Mikko; Lastusaari, Mika

    2017-12-15

    Modificating and protecting the upconversion luminescence nanoparticles is important for their potential in various applications. In this work we demonstrate successful coating of the nanoparticles by a simple layer-by-layer method using negatively charged polyelectrolytes and neodymium ions. The layer fabrication conditions such as number of the bilayers, solution concentrations and selected polyelectrolytes were studied to find the most suitable conditions for the process. The bilayers were characterized and the presence of the desired components was studied and confirmed by various methods. In addition, the upconversion luminescence of the bilayered nanoparticles was studied to see the effect of the surface modification on the overall intensity. It was observed that with selected deposition concentrations the bilayer successfully shielded the particle resulting in stronger upconversion luminescence. The layer-by-layer method offers multiple possibilities to control the bilayer growth even further and thus gives promises that the use of upconverting nanoparticles in applications could become even easier with less modification steps in the future. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Improvement of Surface Layer Characteristics by Shot Lining

    Science.gov (United States)

    Harada, Yasunori

    In the present study, lining of the metal with foils using shot peening was investigated to improve the surface layer characteristics. In the shot peening experiment, the foils set on the metal are pelted with hard particles traveling at a high velocity. The foils are bonded to the metal surface due to plastic deformation induced by the collision of the particles. The foils and the metal are heated to heighten the bondability because of the reduction of flow stress. Lining the metal with the hard powder sandwiched between two aluminum foil sheets was also attempted. In this experiment, a centrifugal shot peening machine wite an electrical heater was employed. The metals are commercially aluminium alloys and magnesium alloys, and the foils are commercially aluminum, titanium and nickel. The effects of shot speed and the heating temperature on the bondability were examined. Wear resistance was also evaluated by grinding. The foils were successfully bonded to the metal surface. It was found that the present method is effective in improving of surface layer characteristics.

  9. In-situ surface hardening of cast iron by surface layer metallurgy

    International Nuclear Information System (INIS)

    Fischer, Sebastian F.; Muschna, Stefan; Bührig-Polaczek, Andreas; Bünck, Matthias

    2014-01-01

    Abrasive wear is a serious problem in many cast iron castings used in industry. To minimize failure and repair of these components, different strategies exist to improve their surface microhardness thus enhancing their wear resistance. However, most of these methods lead to very brittle and/or expensive castings. In the current work a new method for surface hardening is presented which utilizes surface layer metallurgy to generate in-situ a boron-enriched white cast iron surface layer with a high microhardness on a gray cast iron casting. To do this, sand molds are coated with a ferroboron suspension and cast with a cast iron melt. After solidification, a 100–900 µm thick layer of boron-enriched ledeburite is formed on the surface of the casting which produces an increase in the average microhardness from 284 HV 0.1 ±52 HV 0.1 to 505 HV 0.1 ±87 HV 0.1 . Analyses of the samples' core reveal a typical cast iron microstructure which leads to the conclusion that the coating mainly affects the castings' surface. By varying the grain size of the ferroboron powder in the coatings, it is shown that a powder size ≤100 µm is most suitable to create a boron-enriched ledeburite surface layer possessing high hardness values

  10. Study on tribological properties of multi-layer surface texture on Babbitt alloys surface

    Science.gov (United States)

    Zhang, Dongya; Zhao, Feifei; Li, Yan; Li, Pengyang; Zeng, Qunfeng; Dong, Guangneng

    2016-12-01

    To improve tribological properties of Babbitt alloys, multi-layer surface texture consisted of the main grooves and secondary micro-dimples are fabricated on the Babbitt substrate through laser pulse ablation. The tribological behaviors of multi-layer surface texture are investigated using a rotating type pin-on-disc tribo-meter under variation sliding speeds, and the film pressure distributions on the textured surfaces are simulated using computational fluid dynamics (CFD) method for elucidating the possible mechanisms. The results suggest that: (i) the multi-layer surface texture can reduce friction coefficient of Babbitt alloy, which has lowest friction coefficient of 0.03, in case of the groove parameter of 300 μm width and 15% of area density; (ii) the improvement effect may be more sensitive to the groove area density and the siding speed, and the textured surface with lower area density has lower friction coefficient under high sliding speed. Based on the reasons of (i) the secondary micro-dimples on Babbitt alloy possesses a hydrophobicity surface and (ii) the CFD analysis indicates that main grooves enhancing hydrodynamic effect, thus the multi-layer surface texture is regarded as dramatically improve the lubricating properties of the Babbitt alloy.

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

    International Nuclear Information System (INIS)

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

    2010-01-01

    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 2 O 2 ) as oxidizing agent of lead layer on the chromium surface and acetic acid (CH 3 COOH) 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 deg. C), only 15-min time is needed for complete removal of 3 g fouling lead from a chromium surface.

  12. Hot zirconium cathode sputtered layers for useful surface modification

    International Nuclear Information System (INIS)

    Duckworth, R.G.

    1986-01-01

    It has been found that multilayer zirconium based sputtered coatings can greatly improve the wear properties of a wide variety of mechanical components, machine tools, and metal surfaces. Although a hot (approximately 1000 0 C) cathode is employed, temperature sensitive components can be beneficially treated, and for precision parts a total coating thickness of only 0.5μm is often perfectly effective. Even at the highest coating rates substrate temperatures are below 300 0 C. For the corrosion protection of less well finished surfaces thicker layers are usually required and it is important that relatively stress free layers are produced. The authors employed a variety of tailored zirconium/zirconium nitride/zirconium oxide mixed layers to solve a number of tribological problems for some 5 or 6 years. However, it is only recently that they designed, built, and commissioned rapid cycle, multiple cathode, load-lock plant for economic production of such coatings. This paper provides an introduction to this method of depositing pure zirconium and pure synthetic zirconium nitride films

  13. 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.

  14. 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.

  15. Engineering Particle Surface Chemistry and Electrochemistry with Atomic Layer Deposition

    Science.gov (United States)

    Jackson, David Hyman Kentaro

    Atomic layer deposition (ALD) is a vapor phase thin film coating technique that relies on sequential pulsing of precursors that undergo self-limited surface reactions. The self- limiting reactions and gas phase diffusion of the precursors together enable the conformal coating of microstructured particles with a high degree of thickness and compositional control. ALD may be used to deposit thin films that introduce new functionalities to a particle surface. Examples of new functionalities include: chemical reactivity, a mechanically strong protective coating, and an electrically resistive layer. The coatings properties are often dependent on the bulk properties and microstructure of the particle substrate, though they usually do not affect its bulk properties or microstructure. Particle ALD finds utility in the ability to synthesize well controlled, model systems, though it is expensive due to the need for costly metal precursors that are dangerous and require special handling. Enhanced properties due to ALD coating of particles in various applications are frequently described empirically, while the details of their enhancement mechanisms often remain the focus of ongoing research in the field. This study covers the various types of particle ALD and attempts to describe them from the unifying perspective of surface science.

  16. Layer Dependence of Graphene for Oxidation Resistance of Cu Surface

    Institute of Scientific and Technical Information of China (English)

    Yu-qing Song; Xiao-ping Wang

    2017-01-01

    We studied the oxidation resistance of graphene-coated Cu surface and its layer dependence by directly growing monolayer graphene with different multilayer structures coexisted,diminishing the influence induced by residue and transfer technology.It is found that the Cu surface coated with the monolayer graphene demonstrate tremendous difference in oxidation pattern and oxidation rate,compared to that coated with the bilayer graphene,which is considered to be originated from the strain-induced linear oxidation channel in monolayer graphene and the intersection of easily-oxidized directions in each layer of bilayer graphene,respectively.We reveal that the defects on the graphene basal plane but not the boundaries are the main oxidation channel for Cu surface under graphene protection.Our finding indicates that compared to putting forth efforts to improve the quality of monolayer graphene by reducing defects,depositing multilayer graphene directly on metal is a simple and effective way to enhance the oxidation resistance of graphene-coated metals.

  17. Anomalous magnetotransport of a surface electron layer above liquid helium

    International Nuclear Information System (INIS)

    Grigor'ev, V.N.; Kovdrya, Yu.Z.; Nikolaenko, V.A.; Kirichek, O.I.; Shcherbachenko, R.I.

    1991-01-01

    The magnetoconductivity σ xx of a surface electron layer above liquid helium has been measured at temperatures between 0.5-1.6 K, for concentrations up to about 4x10 8 cm -2 , in magnetic fields up to 25 kOe. As was observed, σ xx first decreases with lowering temperature, then has a minimum and at T xy , the earlier ascertained anomalous behaviour of the magnetoresistance ρ xx taken into consideration. The calculated dependence of ρ xx on T is in satisfactory agreement with the anomalous dependence ρ xx (T) found earlier by experiment

  18. Artificial skin and patient simulator comprising the artificial skin

    NARCIS (Netherlands)

    2011-01-01

    The invention relates to an artificial skin (10, 12, 14), and relates to a patient simulator (100) comprising the artificial skin. The artificial skin is a layered structure comprising a translucent cover layer (20) configured for imitating human or animal skin, and comprising a light emitting layer

  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. 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

  1. 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.

  2. 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.

  3. 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...

  4. The laser surface alloying of the surface layer of the plain carbon steel

    International Nuclear Information System (INIS)

    Woldan, A.; Kusinski, J.

    2003-01-01

    The paper describes the microstructure and properties (chemical composition, microhardness and the effect of tribological test of the surface laser alloyed layer with tantalum. Scanning electron microscopy examinations show structure, which consist of martensite and Ta2C carbides. Samples covered with Ta and the carbon containing binder showed after laser alloying higher hardness than in case of using silicon-containing binder. (author)

  5. 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.

  6. 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...

  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. Semiconductor device comprising a pn-heterojunction

    NARCIS (Netherlands)

    2007-01-01

    An electric device is disclosed comprising a pn-heterojunction ( 4 ) formed by a nanowire ( 3 ) of 111 -V semiconductor material and a semiconductor body ( 1 ) comprising a group IV semiconductor material. The nanowire ( 3 ) is positioned in direct contact with the surface ( 2 ) of the semiconductor

  9. 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)

  10. Mixed and mixing layer depths in the ocean surface boundary layer under conditions of diurnal stratification

    Science.gov (United States)

    Sutherland, G.; Reverdin, G.; Marié, L.; Ward, B.

    2014-12-01

    A comparison between mixed (MLD) and mixing (XLD) layer depths is presented from the SubTRopical Atlantic Surface Salinity Experiment (STRASSE) cruise in the subtropical Atlantic. This study consists of 400 microstructure profiles during fairly calm and moderate conditions (2 background level. Two different thresholds for the background dissipation level are tested, 10-8 and 10-9 m2 s-3, and these are compared with the MLD as calculated using a density threshold. The larger background threshold agrees with the MLD during restratification but only extends to half the MLD during nighttime convection, while the lesser threshold agrees well during convection but is deeper by a factor of 2 during restratification. Observations suggest the use of a larger density threshold to determine the MLD in a buoyancy driven regime.

  11. Surface role in reorientation of internal layers of molybdenum single crystal during rolling

    International Nuclear Information System (INIS)

    Antsiforov, P.N.; Gorordetskij, S.D.; Markashova, A.I.; Martynenko, S.I.

    1991-01-01

    Structure, orientations and chemical composition of surface and internal layers of molybdenum rolled monocrystals are studied using electron microscopy, X-ray and Auger-analyses. Model of reorientation allowing to determine relation of deformation mechanism localized in surface layer with reorientation of internal layers, is described to explain the results

  12. Optofluidic Fabry-Pérot Micro-Cavities Comprising Curved Surfaces for Homogeneous Liquid Refractometry—Design, Simulation, and Experimental Performance Assessment

    Directory of Open Access Journals (Sweden)

    Noha Gaber

    2016-04-01

    Full Text Available In the scope of miniaturized optical sensors for liquid refractometry, this work details the design, numerical simulation, and experimental characterization of a Fabry-Pérot resonator consisting of two deeply-etched silicon cylindrical mirrors with a micro-tube in between holding the liquid analyte under study. The curved surfaces of the tube and the cylindrical mirrors provide three-dimensional light confinement and enable achieving stability for the cavity illuminated by a Gaussian beam input. The resonant optofluidic cavity attains a high-quality factor (Q—over 2800—which is necessary for a sensitive refractometer, not only by providing a sharp interference spectrum peak that enables accurate tracing of the peak wavelengths shifts, but also by providing steep side peaks, which enables detection of refractive index changes by power level variations when operating at a fixed wavelength. The latter method can achieve refractometry without the need for spectroscopy tools, provided certain criteria explained in the details are met. By experimentally measuring mixtures of acetone-toluene with different ratios, refractive index variations of 0.0005 < Δn < 0.0022 could be detected, with sensitivity as high as 5500 μW/RIU.

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

    International Nuclear Information System (INIS)

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

    2009-01-01

    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.

  14. 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.

  15. 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)

  16. Boundary layer transition observations on a body of revolution with surface heating and cooling in water

    Science.gov (United States)

    Arakeri, V. H.

    1980-04-01

    Boundary layer flow visualization in water with surface heat transfer was carried out on a body of revolution which had the predicted possibility of laminar separation under isothermal conditions. Flow visualization was by in-line holographic technique. Boundary layer stabilization, including elimination of laminar separation, was observed to take place on surface heating. Conversely, boundary layer destabilization was observed on surface cooling. These findings are consistent with the theoretical predictions of Wazzan et al. (1970).

  17. 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

  18. Surface plasmon polariton modulator with optimized active layer

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Lavrinenko, Andrei

    2012-01-01

    package CST Microwave Studio in the frequency domain. We explore different permittivities of the ITO layer, which can be achieved by utilizing different anneal conditions. To increase transmittance and enhance modulation depth or efficiency, we propose to pattern the continuous active layer. Dependence...... from the pattern size and filling factor of the active material are analyzed for tuned permittivity of the ITO layer. Direct simulation of the device functionality validates optimization design....

  19. Stability conditions of stationary rupture of liquid layers on an immiscible fluid surface

    Energy Technology Data Exchange (ETDEWEB)

    Viviani, A. [Seconda Univ. di Napoli, Aversa (Italy). Facolta di Ingegneria; Kostarev, K.; Shmyrov, A.; Zuev, A. [Inst. of Continuous Media Mechanics, Perm (Russian Federation)

    2009-07-01

    The stationary equilibrium shape of a 3-phase liquids-gas system was investigated. The system consisted of a horizontal liquid layer with an upper free boundary placed on the immiscible fluid interface. The study investigated the stability conditions of rupture of the liquid layer surface. The dependence of rupture parameters on the experimental cuvette diameter and layer thickness was investigated, as well as the difference in the values of surface tension of the examined fluids. The 2-layer system of horizontal fluid layers was formed in a glass cylindrical cuvette. The liquid substrate was tetrachloride carbon (CCI{sub 4}), while upper layers included water, glycerine, ethyleneglycol, and aqueous solutions of 1,4-butanediol C{sub 4}H{sub 10}O{sub 2} and isopropanol C{sub 3H8L}. Initially, the surface of the substrate fluid was overlaid with a horizontal liquid layer. The rupture was formed by subjecting the layer surface to short-time actions of a narrow directional air jet. After rupture formation, the layer thickness increased gradually. The measurements demonstrated that the rupture diameter depends on the initial thickness of the upper layer as well as the diameter of the cuvette, and the difference in the values of the surface tension of the examined fluids. Analysis of the experimental relationships indicated that the critical thickness of the breaking layer is a constant value for any specific pairs of fluids. 4 refs., 7 figs.

  20. 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.

  1. Modelling the artic stable boundary layer and its coupling to the surface

    NARCIS (Netherlands)

    Steeneveld, G.J.; Wiel, van de B.J.H.; Holtslag, A.A.M.

    2006-01-01

    The impact of coupling the atmosphere to the surface energy balance is examined for the stable boundary layer, as an extension of the first GABLS (GEWEX Atmospheric Boundary-Layer Study) one-dimensional model intercomparison. This coupling is of major importance for the stable boundary-layer

  2. Nanophosphor composite scintillators comprising a polymer matrix

    Science.gov (United States)

    Muenchausen, Ross Edward; Mckigney, Edward Allen; Gilbertson, Robert David

    2010-11-16

    An improved nanophosphor composite comprises surface modified nanophosphor particles in a solid matrix. The nanophosphor particle surface is modified with an organic ligand, or by covalently bonding a polymeric or polymeric precursor material. The surface modified nanophosphor particle is essentially charge neutral, thereby preventing agglomeration of the nanophosphor particles during formation of the composite material. The improved nanophosphor composite may be used in any conventional scintillator application, including in a radiation detector.

  3. Soil Surface Organic Layers in Alaska's Arctic Foothills: Development, Distribution and Microclimatic Feedbacks

    Science.gov (United States)

    Baughman, C. A.; Mann, D. H.; Verbyla, D.; Valentine, D.; Kunz, M. L.; Heiser, P. A.

    2013-12-01

    Accumulated organic matter at the ground surface plays an important role in arctic ecosystems. These soil surface organic layers (SSOLs) influence temperature, moisture, and chemistry in the underlying mineral soil and, on a global basis, comprise enormous stores of labile carbon. Understanding the dynamics of SSOLs is prerequisite to modeling the responses of arctic ecosystem processes to climate changes. Here, we ask three questions regarding SSOLs in the Arctic Foothills in northern Alaska: 1) What environmental factors control their spatial distribution? 2) How long do they take to form? 3) What is the relationship between SSOL thickness and mineral soil temperature through the growing season? The best topographically-controlled predictors of SSOL thickness and spatial distribution are duration of sunlight during the growing-season, upslope drainage area, slope gradient, and elevation. SSOLs begin to form within several decades following disturbance but require 500-700 years to reach equilibrium states. Once formed, mature SSOLs lower peak growing-season temperature and mean annual temperature in the underlying mineral horizon by 8° and 3° C respectively, which reduces available growing degree days within the upper mineral soil by nearly 80%. How ongoing climate change in northern Alaska will affect the region's SSOLs is an open and potentially crucial question.

  4. A general analytical equation for phase diagrams of an N-layer ferroelectric thin film with two surface layers

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Z X; Teng, B H; Rong, Y H; Lu, X H; Yang, X [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)], E-mail: phytbh@163.com

    2010-03-15

    Within the framework of effective-field theory with correlations, the phase diagrams of an N-layer ferroelectric thin film with two surface layers are studied by the differential operator technique based on the spin-1/2 transverse Ising model. A general analytical equation for the phase diagram of a ferroelectric thin film with arbitrary layer number as well as exchange interactions and transverse fields is derived, and then the effects of exchange interactions and transverse fields on phase diagrams are discussed for an arbitrary layer number N. Meanwhile, the crossover features, from the ferroelectric-dominant phase diagram (FPD) to the paraelectric-dominant phase diagram (PPD), for various parameters of an N-layer ferroelectric thin film with two surface layers are investigated. As a result, an N-independent common intersection point equation is obtained, and the three-dimensional curved surfaces for the crossover values are constructed. In comparison with the usual mean-field approximation, the differential operator technique with correlations reduces to some extent the ferroelectric features of a ferroelectric thin film.

  5. Layer-by-Layer Heparinization of the Cell Surface by Using Heparin-Binding Peptide Functionalized Human Serum Albumin.

    Science.gov (United States)

    Song, Guowei; Hu, Yaning; Liu, Yusheng; Jiang, Rui

    2018-05-20

    Layer-by-layer heparinization of therapeutic cells prior to transplantation is an effective way to inhibit the instant blood-mediated inflammatory reactions (IBMIRs), which are the major cause of early cell graft loss during post-transplantation. Here, a conjugate of heparin-binding peptide (HBP) and human serum albumin (HSA), HBP-HSA, was synthesized by using heterobifunctional crosslinker. After the first heparin layer was coated on human umbilical vein endothelial cells (HUVECs) by means of the HBP-polyethylene glycol-phospholipid conjugate, HBP-HSA and heparin were then applied to the cell surface sequentially to form multiple layers. The immobilization and retention of heparin were analyzed by confocal microscopy and flow cytometry, respectively, and the cytotoxity of HBP-HSA was further evaluated by cell viability assay. Results indicated that heparin was successfully introduced to the cell surface in a layer-by-layer way and retained for at least 24 h, while the cytotoxity of HBP-HSA was negligible at the working concentration. Accordingly, this conjugate provides a promising method for co-immobilization of heparin and HSA to the cell surface under physiological conditions with improved biocompatibility.

  6. BALLISTIC RESISTANT ARTICLES COMPRISING TAPES

    NARCIS (Netherlands)

    VAN DER EEM, JORIS; HARINGS, JULES; JANSE, GERARDUS; TJADEN, HENDRIK

    2015-01-01

    The invention pertains to a ballistic-resistant moulded article comprising a compressed stack of sheets comprising reinforcing tapes having a tensile strength of at least 1.0 GPa, a tensile modulus of at least 40 GPa, and a tensile energy-to-break of at least 15 J/g, the direction of the tapes

  7. 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

  8. Nanoscale multiple gaseous layers on a hydrophobic surface.

    Science.gov (United States)

    Zhang, Lijuan; Zhang, Xuehua; Fan, Chunhai; Zhang, Yi; Hu, Jun

    2009-08-18

    The nanoscale gas state at the interfaces of liquids (water, acid, and salt solutions) and highly oriented pyrolytic graphite (HOPG) was investigated via tapping-mode atomic force microscopy (AFM). For the first time, we report that the interfacial gases could form bilayers and trilayers, i.e., on the top of a flat gas layer, there are one or two more gas layers. The formation of these gas layers could be induced by a local supersaturation of gases, which can be achieved by (1) temperature difference between the liquids and the HOPG substrates or (2) exchange ethanol with water. Furthermore, we found that the gas layers were less stable than spherical bubbles. They could transform to bubbles with time or under the perturbation of the AFM tip.

  9. 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

  10. Investigation of surface layer on rolled recycled AA5050 in relation to Filiform Corrosion

    NARCIS (Netherlands)

    2007-01-01

    The presence of a heavily deformed surface layer (a few microns thick) on rolled aluminium alloy is understood to be one of the main reasons contributing to the Filiform Corrosion (FFC) susceptibility of the alloy. The surface layer is formed during the thermo-mechanical processing of the sheet

  11. DEPTH MEASUREMENT OF DISRUPTED LAYER ON SILICON WAFER SURFACE USING AUGER SPECTROSCOPY METHOD

    Directory of Open Access Journals (Sweden)

    V. A. Solodukha

    2016-01-01

    Full Text Available The paper proposes a method for depth measurement of a disrupted layer on silicon wafer surface which is based on application of Auger spectroscopy with the precision sputtering of surface silicon layers and registration of the Auger electron yield intensity. In order to measure the disrupted layer with the help of Auger spectroscopy it is necessary to determine dependence of the released Auger electron amount on sputtering time (profile and then the dependence is analyzed. Silicon amount in the disrupted layer is less than in the volume. While going deeper the disruptive layer is decreasing that corresponds to an increase of atom density in a single layer. The essence of the method lies in the fact the disruptive layer is removed by ion beam sputtering and detection of interface region is carried out with the help of registration of the Auger electron yield intensity from the sputtered surface up to the moment when it reaches the value which is equal to the Auger electron yield intensity for single-crystal silicon. While removing surface silicon layers the registration of the Auger electron yield intensity from silicon surface makes it possible to control efficiently a presence of the disrupted layer on the silicon wafer surface. In this case depth control locality is about 1.0 nm due to some peculiarities of Auger spectroscopy method. The Auger electron yield intensity is determined automatically while using Auger spectrometer and while removing the disrupted layer the intensity is gradually increasing. Depth of the disrupted layer is determined by measuring height of the step which has been formed as a result of removal of the disrupted layer from the silicon wafer surface. Auger spectroscopy methods ensures an efficient depth control surface disruptions at the manufacturing stages of silicon wafers and integrated circuits. The depth measurement range of disruptions constitutes 0.001–1.000 um.

  12. Doped LZO buffer layers for laminated conductors

    Science.gov (United States)

    Paranthaman, Mariappan Parans [Knoxville, TN; Schoop, Urs [Westborough, MA; Goyal, Amit [Knoxville, TN; Thieme, Cornelis Leo Hans [Westborough, MA; Verebelyi, Darren T [Oxford, MA; Rupich, Martin W [Framingham, MA

    2010-03-23

    A laminated conductor includes a metallic substrate having a surface, a biaxially textured buffer layer supported by the surface of the substrate, the biaxially textured buffer layer comprising LZO and a dopant for mitigating metal diffusion through the LZO, and a biaxially textured conductor layer supported by the biaxially textured buffer layer.

  13. On the Existence of the Logarithmic Surface Layer in the Inner Core of Hurricanes

    Science.gov (United States)

    2012-01-01

    characteristics of eyewall boundary layer of Hurricane Hugo (1989). Mon. Wea. Rev., 139, 1447-1462. Zhang, JA, Montgomery MT. 2012 Observational...the inner core of hurricanes Roger K. Smitha ∗and Michael T. Montgomeryb a Meteorological Institute, University of Munich, Munich, Germany b Dept. of...logarithmic surface layer”, or log layer, in the boundary layer of the rapidly-rotating core of a hurricane . One such study argues that boundary-layer

  14. Cu and Cu(Mn) films deposited layer-by-layer via surface-limited redox replacement and underpotential deposition

    Energy Technology Data Exchange (ETDEWEB)

    Fang, J.S., E-mail: jsfang@nfu.edu.tw [Department of Materials Science and Engineering, National Formosa University, Huwei 63201, Taiwan (China); Sun, S.L. [Department of Materials Science and Engineering, National Formosa University, Huwei 63201, Taiwan (China); Cheng, Y.L. [Department of Electrical Engineering, National Chi-Nan University, Nan-Tou 54561, Taiwan (China); Chen, G.S.; Chin, T.S. [Department of Materials Science and Engineering, Feng Chia University, Taichung 40724, Taiwan (China)

    2016-02-28

    Graphical abstract: - Abstract: The present paper reports Cu and Cu(Mn) films prepared layer-by-layer using an electrochemical atomic layer deposition (ECALD) method. The structure and properties of the films were investigated to elucidate their suitability as Cu interconnects for microelectronics. Previous studies have used primarily a vacuum-based atomic layer deposition to form a Cu metallized film. Herein, an entirely wet chemical process was used to fabricate a Cu film using the ECALD process by combining underpotential deposition (UPD) and surface-limited redox replacement (SLRR). The experimental results indicated that an inadequate UPD of Pb affected the subsequent SLRR of Cu and lead to the formation of PbSO{sub 4}. A mechanism is proposed to explain the results. Layer-by-layer deposition of Cu(Mn) films was successfully performed by alternating the deposition cycle-ratios of SLRR-Cu and UPD-Mn. The proposed self-limiting growth method offers a layer-by-layer wet chemistry-based deposition capability for fabricating Cu interconnects.

  15. 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.

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

    International Nuclear Information System (INIS)

    Shu, Y.; Zou, J.; Ou, G.; Wang, L.; Li, Q.

    2011-01-01

    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

  17. 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

  18. Surface Passivation by Quantum Exclusion Using Multiple Layers

    Science.gov (United States)

    Hoenk, Michael E. (Inventor)

    2015-01-01

    A semiconductor device has a multilayer doping to provide improved passivation by quantum exclusion. The multilayer doping includes at least two doped layers fabricated using MBE methods. The dopant sheet densities in the doped layers need not be the same, but in principle can be selected to be the same sheet densities or to be different sheet densities. The electrically active dopant sheet densities are quite high, reaching more than 1.times.10.sup.14 cm.sup.-2, and locally exceeding 10.sup.22 per cubic centimeter. It has been found that silicon detector devices that have two or more such dopant layers exhibit improved resistance to degradation by UV radiation, at least at wavelengths of 193 nm, as compared to conventional silicon p-on-n devices.

  19. Thermal healing of the sub-surface damage layer in sapphire

    International Nuclear Information System (INIS)

    Pinkas, Malki; Lotem, Haim; Golan, Yuval; Einav, Yeheskel; Golan, Roxana; Chakotay, Elad; Haim, Avivit; Sinai, Ela; Vaknin, Moshe; Hershkovitz, Yasmin; Horowitz, Atara

    2010-01-01

    The sub-surface damage layer formed by mechanical polishing of sapphire is known to reduce the mechanical strength of the processed sapphire and to degrade the performance of sapphire based components. Thermal annealing is one of the methods to eliminate the sub-surface damage layer. This study focuses on the mechanism of thermal healing by studying its effect on surface topography of a- and c-plane surfaces, on the residual stresses in surface layers and on the thickness of the sub-surface damage layer. An atomically flat surface was developed on thermally annealed c-plane surfaces while a faceted roof-top topography was formed on a-plane surfaces. The annealing resulted in an improved crystallographic perfection close to the sample surface as was indicated by a noticeable decrease in X-ray rocking curve peak width. Etching experiments and surface roughness measurements using white light interferometry with sub-nanometer resolution on specimens annealed to different extents indicate that the sub-surface damage layer of the optically polished sapphire is less than 3 μm thick and it is totally healed after thermal treatment at 1450 deg. C for 72 h.

  20. 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...

  1. 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

  2. Modifying of Cotton Fabric Surface with Nano-ZnO Multilayer Films by Layer-by-Layer Deposition Method

    Directory of Open Access Journals (Sweden)

    Sarıışık Merih

    2010-01-01

    Full Text Available Abstract ZnO nanoparticle–based multilayer nanocomposite films were fabricated on cationized woven cotton fabrics via layer-by-layer molecular self-assembly technique. For cationic surface charge, cotton fabrics were pretreated with 2,3-epoxypropyltrimethylammonium chloride (EP3MAC by pad-batch method. XPS and SEM were used to examine the deposited nano-ZnO multilayer films on the cotton fabrics. The nano-ZnO films deposited on cotton fabrics exhibited excellent antimicrobial activity against Staphylococcus aureus bacteria. The results also showed that the coated fabrics with nano-ZnO multilayer films enhanced the protection of cotton fabrics from UV radiation. Physical tests (tensile strength of weft and warp yarns, air permeability and whiteness values were performed on the fabrics before and after the treatment with ZnO nanoparticles to evaluate the effect of layer-by-layer (LbL process on cotton fabrics properties.

  3. Layer-by-layer modification of high surface curvature nanoparticles with weak polyelectrolytes using a multiphase solvent precipitation process.

    Science.gov (United States)

    Nagaraja, Ashvin T; You, Yil-Hwan; Choi, Jeong-Wan; Hwang, Jin-Ha; Meissner, Kenith E; McShane, Michael J

    2016-03-15

    The layer-by-layer modification of ≈5 nm mercaptocarboxylic acid stabilized gold nanoparticles was studied in an effort to illustrate effective means to overcome practical issues in handling and performing surface modification of such extremely small materials. To accomplish this, each layer deposition cycle was separated into a multi-step process wherein solution pH was controlled in two distinct phases of polyelectrolyte adsorption and centrifugation. Additionally, a solvent precipitation step was introduced to make processing more amenable by concentrating the sample and exchanging solution pH before ultracentrifugation. The pH-dependent assembly on gold nanoparticles was assessed after each layer deposition cycle by monitoring the plasmon peak absorbance location, surface charge, and the percentage of nanoparticles recovered. The selection of solution pH during the adsorption phase was found to be a critical parameter to enhance particle recovery and maximize surface charge when coating with weak polyelectrolytes. One bilayer was deposited with a high yield and the modified particles exhibited enhanced colloidal stability across a broad pH range and increased ionic strength. These findings support the adoption of this multi-step processing approach as an effective and generalizable approach to improve stability of high surface curvature particles. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. X-ray spectrum microanalysis of copper and stainless steel surface layer after electroerosion machining

    International Nuclear Information System (INIS)

    Abdukarimov, Eh.T.; Saidinov, S.Ya.

    1989-01-01

    The results of experimental investigations of the surface layer of copper and steel 12Kh18N10T after electroerrosion treatment by a rotating tungsten electrode in natural and distilled water are presented. It is established that the quantity of electrode material transferred to the surface of the steel treated grows with the spark discharge energy increase. Tungsten concentration in the surface layer reaches 5-10% with the average depth of penetration 40-50 μm

  5. Effect of surface wave propagation in a four-layered oceanic crust model

    Science.gov (United States)

    Paul, Pasupati; Kundu, Santimoy; Mandal, Dinbandhu

    2017-12-01

    Dispersion of Rayleigh type surface wave propagation has been discussed in four-layered oceanic crust. It includes a sandy layer over a crystalline elastic half-space and over it there are two more layers—on the top inhomogeneous liquid layer and under it a liquid-saturated porous layer. Frequency equation is obtained in the form of determinant. The effects of the width of different layers as well as the inhomogeneity of liquid layer, sandiness of sandy layer on surface waves are depicted and shown graphically by considering all possible case of the particular model. Some special cases have been deduced, few special cases give the dispersion equation of Scholte wave and Stoneley wave, some of which have already been discussed elsewhere.

  6. 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.

  7. 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

  8. 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

  9. Formation of Pentacene wetting layer on the SiO2 surface and charge trap in the wetting layer

    International Nuclear Information System (INIS)

    Kim, Chaeho; Jeon, D.

    2008-01-01

    We studied the early-stage growth of vacuum-evaporated pentacene film on a native SiO 2 surface using atomic force microscopy and in-situ spectroscopic ellipsometry. Pentacene deposition prompted an immediate change in the ellipsometry spectra, but atomic force microscopy images of the early stage films did not show a pentacene-related morphology other than the decrease in the surface roughness. This suggested that a thin pentacene wetting layer was formed by pentacene molecules lying on the surface before the crystalline islands nucleated. Growth simulation based on the in situ spectroscopic ellipsometry spectra supported this conclusion. Scanning capacitance microscopy measurement indicated the existence of trapped charges in the SiO 2 and pentacene wetting layer

  10. Formation and Characterization of Stacked Nanoscale Layers of Polymers and Silanes on Silicon Surfaces

    Science.gov (United States)

    Ochoa, Rosie; Davis, Brian; Conley, Hiram; Hurd, Katie; Linford, Matthew R.; Davis, Robert C.

    2008-10-01

    Chemical surface patterning at the nanoscale is a critical component of chemically directed assembly of nanoscale devices or sensitive biological molecules onto surfaces. Complete and consistent formation of nanoscale layers of silanes and polymers is a necessary first step for chemical patterning. We explored methods of silanizing silicon substrates for the purpose of functionalizing the surfaces. The chemical functionalization, stability, flatness, and repeatability of the process was characterized by use of ellipsometry, water contact angle, and Atomic Force Microscopy (AFM). We found that forming the highest quality functionalized surfaces was accomplished through use of chemical vapor deposition (CVD). Specifically, surfaces were plasma cleaned and hydrolyzed before the silane was applied. A polymer layer less then 2 nm in thickness was electrostatically bound to the silane layer. The chemical functionalization, stability, flatness, and repeatability of the process was also characterized for the polymer layer using ellipsometry, water contact angle, and AFM.

  11. Characterization of SCC crack tips and surface oxide layers in alloy 600

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Katsuhiko; Fukuya, Koji [Inst. of Nuclear Safety System Inc., Mihama, Fukui (Japan)

    2002-09-01

    In order to investigate the mechanism of primary water stress corrosion cracking (SCC), direct observation of microstructures of SCC crack tips and surface oxide layers in alloy 600 were carried out. A focused-ion beam (FIB) micro-processing technique was applied to prepare electron transparent foils including the crack tip and the surface oxide layer without any damage to those microstructures. Transmission electron microscopy and analysis were used to characterize the crack tips and surface oxide layers. Cr-rich oxides and a metal-Ni phase were identified in the crack tips and grain boundaries ahead of the crack tips independent of dissolved hydrogen concentrations. >From the fact that the Cr-rich oxides and metal-Ni phase were observed in the inner surface oxide layer, the same oxidation mechanism as the surface is proposed for the crack tip region and internal oxidation accompanying selective Cr oxidation is suggested as the mechanism. (author)

  12. Boundary layer development on turbine airfoil suction surfaces

    Science.gov (United States)

    Sharma, O. P.; Wells, R. A.; Schlinker, R. H.; Bailey, D. A.

    1981-01-01

    The results of a study supported by NASA under the Energy Efficient Engine Program, conducted to investigate the development of boundary layers under the influence of velocity distributions that simulate the suction sides of two state-of-the-art turbine airfoils, are presented. One velocity distribution represented a forward loaded airfoil ('squared-off' design), while the other represented an aft loaded airfoil ('aft loaded' design). These velocity distributions were simulated in a low-speed, high-aspect-ratio wind tunnel specifically designed for boundary layer investigations. It is intended that the detailed data presented in this paper be used to develop improved turbulence model suitable for application to turbine airfoil design.

  13. Mixed convection boundary layer flow over a vertical surface embedded in a thermally stratified porous medium

    International Nuclear Information System (INIS)

    Ishak, Anuar; Nazar, Roslinda; Pop, Ioan

    2008-01-01

    The mixed convection boundary layer flow through a stable stratified porous medium bounded by a vertical surface is investigated. The external velocity and the surface temperature are assumed to vary as x m , where x is measured from the leading edge of the vertical surface and m is a constant. Numerical solutions for the governing Darcy and energy equations are obtained. The results indicate that the thermal stratification significantly affects the surface shear stress as well as the surface heat transfer, besides delays the boundary layer separation

  14. 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

  15. Turbulence Scaling Comparisons in the Ocean Surface Boundary Layer

    Science.gov (United States)

    Esters, L.; Breivik, Ø.; Landwehr, S.; ten Doeschate, A.; Sutherland, G.; Christensen, K. H.; Bidlot, J.-R.; Ward, B.

    2018-03-01

    Direct observations of the dissipation rate of turbulent kinetic energy, ɛ, under open ocean conditions are limited. Consequently, our understanding of what chiefly controls dissipation in the open ocean, and its functional form with depth, is poorly constrained. In this study, we report direct open ocean measurements of ɛ from the Air-Sea Interaction Profiler (ASIP) collected during five different cruises in the Atlantic Ocean. We then combine these data with ocean-atmosphere flux measurements and wave information in order to evaluate existing turbulence scaling theories under a diverse set of open ocean conditions. Our results do not support the presence of a "breaking" or a "transition layer," which has been previously suggested. Instead, ɛ decays as |z|-1.29 over the depth interval, which was previously defined as "transition layer," and as |z|-1.15 over the mixing layer. This depth dependency does not significantly vary between nonbreaking or breaking wave conditions. A scaling relationship based on the friction velocity, the wave age, and the significant wave height describes the observations best for daytime conditions. For conditions during which convection is important, it is necessary to take buoyancy forcing into account.

  16. 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.

  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. 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.

  19. 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)

  20. Low-cycle fatigue of sheet elements with ''soft'' surface layer

    International Nuclear Information System (INIS)

    Luk'yanov, V.F.; Kharchenko, V.Ya.; Berezutskij, V.I.; Ovsyannikov, V.G.

    1978-01-01

    Investigated are regularities of low-cycle fatigue of bimetallic sheet constructions made of chrome-nickel-molybdenum steel, plated with a low-alloyed steel with a reduced yield limit. Static repeated bending tests have been carried out using two-layer samples. The surface layer has been shown to increase resistance to nucleation and propagation of cracks under pulsating load if stresses are not more than 2 times higher than the yield limit. Increase in stresses leads to elastoplastic deformation and reduces durability. The positive effect of the surface layer is advisable to be used when welding-up surface defects and strengthening welded joints of high-strength steels

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

    International Nuclear Information System (INIS)

    Chubenko, E. B.; Redko, S. V.; Sherstnyov, A. I.; Petrovich, V. A.; Kotov, D. A.; Bondarenko, V. P.

    2016-01-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Dziadoń, Andrzej [Faculty of Mechatronics and Mechanical Engineering, Kielce University of Technology, Al. Tysiąclecia P.P. 7, 25-314 Kielce (Poland); Mola, Renata, E-mail: rmola@tu.kielce.pl [Faculty of Mechatronics and Mechanical Engineering, Kielce University of Technology, Al. Tysiąclecia P.P. 7, 25-314 Kielce (Poland); Błaż, Ludwik [Department of Structure and Mechanics of Solids, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków (Poland)

    2016-08-15

    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{sub 3}Mg{sub 2}, Mg{sub 17}Al{sub 12} and Mg{sub 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{sub 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.

  3. 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.

  4. Functionalised nanoscale coatings using layer-by-layer assembly for imparting antibacterial properties to polylactide-co-glycolide surfaces.

    Science.gov (United States)

    Gentile, Piergiorgio; Frongia, Maria E; Cardellach, Mar; Miller, Cheryl A; Stafford, Graham P; Leggett, Graham J; Hatton, Paul V

    2015-07-01

    In order to achieve high local biological activity and reduce the risk of side effects of antibiotics in the treatment of periodontal and bone infections, a localised and temporally controlled delivery system is desirable. The aim of this research was to develop a functionalised and resorbable surface to contact soft tissues to improve the antibacterial behaviour during the first week after its implantation in the treatment of periodontal and bone infections. Solvent-cast poly(d,l-lactide-co-glycolide acid) (PLGA) films were aminolysed and then modified by Layer-by-Layer technique to obtain a nano-layered coating using poly(sodium4-styrenesulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) as polyelectrolytes. The water-soluble antibiotic, metronidazole (MET), was incorporated from the ninth layer. Infrared spectroscopy showed that the PSS and PAH absorption bands increased with the layer number. The contact angle values had a regular alternate behaviour from the ninth layer. X-ray Photoelectron Spectroscopy evidenced two distinct peaks, N1s and S2p, indicating PAH and PSS had been introduced. Atomic Force Microscopy showed the presence of polyelectrolytes on the surface with a measured roughness about 10nm after 20 layers' deposition. The drug release was monitored by Ultraviolet-visible spectroscopy showing 80% loaded-drug delivery in 14 days. Finally, the biocompatibility was evaluated in vitro with L929 mouse fibroblasts and the antibacterial properties were demonstrated successfully against the keystone periodontal bacteria Porphyromonas gingivalis, which has an influence on implant failure, without compromising in vitro biocompatibility. In this study, PLGA was successfully modified to obtain a localised and temporally controlled drug delivery system, demonstrating the potential value of LbL as a coating technology for the manufacture of medical devices with advanced functional properties. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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......, various thiols and allyl or other vinyl reactants can be used to obtain either soft and flexible1 or more rigid functional thermosets 2. The methodology permits use of etiher thermal or photochemical conditions both for matrix preparation as well as for surface functionalization. Due to excess reactive...... 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...

  10. Ionic liquids comprising heteraromatic anions

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, William F.; Brennecke, Joan F.; Maginn, Edward J.; Mindrup, Elaine; Gurkan, Burcu; Price, Erica; Goodrich, Brett

    2018-04-24

    Some embodiments described herein relate to ionic liquids comprising an anion of a heteraromatic compound such as optionally substituted pyrrolide, optionally substituted pyrazolide, optionally substituted indolide, optionally substituted phospholide, or optionally substituted imidazolide. Methods and devices for gas separation or gas absorption related to these ionic liquids are also described herein.

  11. 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

  12. Influence of ploughshare surface layers on ploughing efficiency

    Directory of Open Access Journals (Sweden)

    Z. Horvat

    2018-01-01

    Full Text Available The paper presents comparison between standard ploughshares made of manganese steel 50Mn7 and the authors’ ploughshares hardfaced with a layer of C-Co-Cr-Ni-Si on the same steel. The research was carried out by using two tractors with two four-furrow plough of the same power in a total of 360 working hours, and a total of 180 hours of ploughing with each ploughshare. Ploughshares were used to measure hardness, to analyse the structure and wear.

  13. Fluid-membrane tethers: minimal surfaces and elastic boundary layers.

    Science.gov (United States)

    Powers, Thomas R; Huber, Greg; Goldstein, Raymond E

    2002-04-01

    Thin cylindrical tethers are common lipid bilayer membrane structures, arising in situations ranging from micromanipulation experiments on artificial vesicles to the dynamic structure of the Golgi apparatus. We study the shape and formation of a tether in terms of the classical soap-film problem, which is applied to the case of a membrane disk under tension subject to a point force. A tether forms from the elastic boundary layer near the point of application of the force, for sufficiently large displacement. Analytic results for various aspects of the membrane shape are given.

  14. Surface planarization effect of siloxane derivatives in organic semiconductor layers

    Energy Technology Data Exchange (ETDEWEB)

    Sakanoue, Kei [Center for Organic Photonics and Electronics Research, Kyushu University, Nishi-ku, Fukuoka 819-0395 (Japan); Harada, Hironobu; Ando, Kento [Department of Chemical Engineering, Graduate School of Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395 (Japan); Yahiro, Masayuki [Institute of Systems, Information Technologies and Nanotechnologies, 2-1-22, Sawara-ku, Fukuoka 814-0001 (Japan); Fukai, Jun, E-mail: jfukai@chem-eng.kyushu-u.ac.jp [Department of Chemical Engineering, Graduate School of Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395 (Japan)

    2015-12-31

    The ability of siloxane surface control additives (SCAs) to planarize organic semiconductor films with a thickness of tens of nanometers printed on indium tin oxide (ITO) surfaces with stripe-patterned bank structures using a liquid-phase method is demonstrated. Three types of SCAs with different molecular structures are examined in organic solutions of toluene, anisole and tetralin containing N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)-benzidine as a solute and typical organic semiconductor. While there is an optimum SCA and concentration for each solution, one type of SCA is comprehensively effective for all solutions. This SCA increased contact angle, which is contrary to the typical behavior of SCAs. Scanning electron microscope images of the thin films near the banks reveal that this SCA did not change the contact area between the film and substrate surface, which is related to the effectiveness of the SCA. SCAs did not affect the current–voltage characteristics of green organic light-emitting diodes, but did increase external quantum efficiencies, suggesting that SCAs can be used to improve the quality of solution-deposited films for use in optical devices. - Highlights: • Surface control additives planarize organic semiconductor films coated on surfaces. • The most effective additive increases the contact angle of solutions during drying. • The effect of additives is deduced from solutal Marangoni forces. • Additives have little effect on organic light-emitting diode performance.

  15. Surface planarization effect of siloxane derivatives in organic semiconductor layers

    International Nuclear Information System (INIS)

    Sakanoue, Kei; Harada, Hironobu; Ando, Kento; Yahiro, Masayuki; Fukai, Jun

    2015-01-01

    The ability of siloxane surface control additives (SCAs) to planarize organic semiconductor films with a thickness of tens of nanometers printed on indium tin oxide (ITO) surfaces with stripe-patterned bank structures using a liquid-phase method is demonstrated. Three types of SCAs with different molecular structures are examined in organic solutions of toluene, anisole and tetralin containing N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)-benzidine as a solute and typical organic semiconductor. While there is an optimum SCA and concentration for each solution, one type of SCA is comprehensively effective for all solutions. This SCA increased contact angle, which is contrary to the typical behavior of SCAs. Scanning electron microscope images of the thin films near the banks reveal that this SCA did not change the contact area between the film and substrate surface, which is related to the effectiveness of the SCA. SCAs did not affect the current–voltage characteristics of green organic light-emitting diodes, but did increase external quantum efficiencies, suggesting that SCAs can be used to improve the quality of solution-deposited films for use in optical devices. - Highlights: • Surface control additives planarize organic semiconductor films coated on surfaces. • The most effective additive increases the contact angle of solutions during drying. • The effect of additives is deduced from solutal Marangoni forces. • Additives have little effect on organic light-emitting diode performance.

  16. Stormwater infiltration and surface runoff pollution reduction performance of permeable pavement layers.

    Science.gov (United States)

    Niu, Zhi-Guang; Lv, Zhi-Wei; Zhang, Ying; Cui, Zhen-Zhen

    2016-02-01

    In this paper, the laboratory-scale permeable pavement layers, including a surface permeable brick layer, coarse sand bedding layers (thicknesses = 2, 3.5, and 5 cm), and single-graded gravel sub-base layers (thicknesses = 15, 20, 25, and 30 cm), were built to evaluate stormwater infiltration and surface runoff pollution reduction performance. And, the infiltration rate (I) and concentrations of suspended solids (SS), total phosphorus (TP), chemical oxygen demand (COD), ammonia nitrogen, and total nitrogen (TN) were measured under the simulated rainfall intensity of 72.4 mm/h over duration of 60 min. The results indicate that the thickness factor primarily influences the infiltration rate and pollutant removal rate. The highest steady infiltration rate was for surface brick layer 51.0 mm/h, for 5-cm sand bedding layer 32.3 mm/h, and for 30-cm gravel sub-base layer 42.3 mm/h, respectively. The SS average removal rate was relative higher (79.8 ∼ 98.6 %) for all layers due to the interception and filtration. The average removal rates of TP and COD were for surface layer 71.2 and 24.1 %, for 5-cm bedding layer 54.8 and 9.0 %, and for 20-cm sub-base layer 72.2 and 26.1 %. Ammonia nitrogen and TN cannot steadily be removed by layers according to the experiment results. The optimal thickness of bedding sands was 5 cm, and that of sub-base gravels was 20 ∼ 30 cm.

  17. Two-Layer Variable Infiltration Capacity Land Surface Representation for General Circulation Models

    Science.gov (United States)

    Xu, L.

    1994-01-01

    A simple two-layer variable infiltration capacity (VIC-2L) land surface model suitable for incorporation in general circulation models (GCMs) is described. The model consists of a two-layer characterization of the soil within a GCM grid cell, and uses an aerodynamic representation of latent and sensible heat fluxes at the land surface. The effects of GCM spatial subgrid variability of soil moisture and a hydrologically realistic runoff mechanism are represented in the soil layers. The model was tested using long-term hydrologic and climatalogical data for Kings Creek, Kansas to estimate and validate the hydrological parameters. Surface flux data from three First International Satellite Land Surface Climatology Project Field Experiments (FIFE) intensive field compaigns in the summer and fall of 1987 in central Kansas, and from the Anglo-Brazilian Amazonian Climate Observation Study (ABRACOS) in Brazil were used to validate the mode-simulated surface energy fluxes and surface temperature.

  18. The endothelial surface layer: a new target of research in kidney failure and peritoneal dialysis

    NARCIS (Netherlands)

    Vlahu, C.A.

    2016-01-01

    The endothelial glycocalyx is an important regulator of vascular homeostasis, and damage to this complex structure results in increased vascular vulnerability. Together with associated plasma molecules it forms the endothelial surface layer. Because of its vasculoprotective effects, the endothelial

  19. Atmospheric Surface Layer Characterization: Preliminary Desert Lapse Rate Study 22-25 August 2000

    National Research Council Canada - National Science Library

    Elliott, Doyle

    2003-01-01

    Results of the August 2000 Desert Lapse Rate (DLR) Experiment are presented. The DLR Experiment was performed to document the night-to-day transition effects on the desert Atmospheric Surface Layer (ASL...

  20. 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)

  1. FDTD Investigation on Electromagnetic Scattering from Two-Layered Rough Surfaces under UPML Absorbing Condition

    International Nuclear Information System (INIS)

    Juan, Li; Li-Xin, Guo; Hao, Zeng

    2009-01-01

    Electromagnetic scattering from one-dimensional two-layered rough surfaces is investigated by using finite-difference time-domain algorithm (FDTD). The uniaxial perfectly matched layer (UPML) medium is adopted for truncation of FDTD lattices, in which the finite-difference equations can be used for the total computation domain by properly choosing the uniaxial parameters. The rough surfaces are characterized with Gaussian statistics for the height and the autocorrelation function. The angular distribution of bistatic scattering coefficient from single-layered perfect electric conducting and dielectric rough surface is calculated and it is in good agreement with the numerical result with the conventional method of moments. The influence of the relative permittivity, the incident angle, and the correlative length of two-layered rough surfaces on the bistatic scattering coefficient with different polarizations are presented and discussed in detail. (fundamental areas of phenomenology (including applications))

  2. 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).

  3. 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.

  4. Surface analysis of uranyl fluoride layers with a glow discharge lamp

    International Nuclear Information System (INIS)

    Nel, J.T.; Stander, C.M.; Boehmer, R.G.

    1991-01-01

    Surface analysis with a Grimm-type glow discharge lamp was used to analyse uranyl fluoride layers that had formed on a nickel substrate after exposure to UF 6 . Narrow-band optical filters were used to isolate the intensities of three fluorine emission lines. An in-depth profile of layer composition was obtained. (author)

  5. X-ray diffraction study of surface-layer structure in parallel grazing rays

    International Nuclear Information System (INIS)

    Shtypulyak, N.I.; Yakimov, I.I.; Litvintsev, V.V.

    1989-01-01

    An x-ray diffraction method is described for study of thin polycrystalline and amorphous films and surface layers in an extremely asymmetrical diffraction system in parallel grazing rays using a DRON-3.0 diffractometer. The minimum grazing angles correspond to diffraction under conditions of total external reflection and a layer depth of ∼ 2.5-8 nm

  6. 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.

  7. 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...

  8. Surface Morphology Transformation Under High-Temperature Annealing of Ge Layers Deposited on Si(100).

    Science.gov (United States)

    Shklyaev, A A; Latyshev, A V

    2016-12-01

    We study the surface morphology and chemical composition of SiGe layers after their formation under high-temperature annealing at 800-1100 °C of 30-150 nm Ge layers deposited on Si(100) at 400-500 °C. It is found that the annealing leads to the appearance of the SiGe layers of two types, i.e., porous and continuous. The continuous layers have a smoothened surface morphology and a high concentration of threading dislocations. The porous and continuous layers can coexist. Their formation conditions and the ratio between their areas on the surface depend on the thickness of deposited Ge layers, as well as on the temperature and the annealing time. The data obtained suggest that the porous SiGe layers are formed due to melting of the strained Ge layers and their solidification in the conditions of SiGe dewetting on Si. The porous and dislocation-rich SiGe layers may have properties interesting for applications.

  9. Structural features of the adsorption layer of pentacene on the graphite surface and the PMMA/graphite hybrid surface

    Science.gov (United States)

    Fadeeva, A. I.; Gorbunov, V. A.; Litunenko, T. A.

    2017-08-01

    Using the molecular dynamics and the Monte Carlo methods, we have studied the structural features and growth mechanism of the pentacene film on graphite and polymethylmethacrylate /graphite surfaces. Monolayer capacity and molecular area, optimal angles between the pentacene molecules and graphite and PMMA/graphite surfaces as well as the characteristic angles between the neighboring pentacene molecules in the adsorption layer were estimated. It is shown that the orientation of the pentacene molecules in the film is determined by a number of factors, including the surface concentration of the molecules, relief of the surface, presence or absence of the polymer layer and its thickness. The pentacene molecules adsorbed on the graphite surface keep a horizontal position relative to the long axis at any surface coverage/thickness of the film. In the presence of the PMMA layer on the graphite, the increase of the number of pentacene molecules as well as the thickness of the PMMA layer induce the change of molecular orientation from predominantly horizontal to vertical one. The reason for such behavior is supposed to be the roughness of the PMMA surface.

  10. Changes of electrical conductivity of the metal surface layer by the laser alloying with foreign elements

    Science.gov (United States)

    Kostrubiec, Franciszek; Pawlak, Ryszard; Raczynski, Tomasz; Walczak, Maria

    1994-09-01

    Laser treatment of the surface of materials is of major importance for many fields technology. One of the latest and most significant methods of this treatment is laser alloying consisting of introducing foreign atoms into the metal surface layer during the reaction of laser radiation with the surface. This opens up vast possibilities for the modification of properties of such a layer (obtaining layers of increased microhardness, increased resistance to electroerosion in an electric arc, etc.). Conductivity of the material is a very important parameter in case of conductive materials used for electrical contacts. The paper presents the results of studies on change in electrical conductivity of the surface layer of metals alloyed with a laser. A comparative analysis of conductivity of base metal surface layers prior to and following laser treatment has been performed. Depending on the base metal and the alloying element, optical treatment parameters allowing a required change in the surface layer conductivity have been selected. A very important property of the contact material is its resistance to plastic strain. It affects the real value of contact surface coming into contact and, along with the material conductivity, determines contact resistance and the amount of heat generated in place of contact. These quantities are directly related to the initiation and the course of an arc discharge, hence they also affect resistance to electroerosion. The parameter that reflects plastic properties with loads concentrated on a small surface, as is the case with a reciprocal contact force of two real surfaces with their irregularities being in contact, is microhardness. In the paper, the results of investigations into microhardness of modified surface layers compared with base metal microhardness have been presented.

  11. Detection of Entrainment Influences on Surface-Layer Measurements and Extension of Monin–Obukhov Similarity Theory

    NARCIS (Netherlands)

    Boer, van de A.; Moene, A.F.; Graf, A.; Schüttemeyer, D.; Simmer, C.

    2014-01-01

    We present a method to detect influences of boundary-layer processes on surface-layer measurements, using statistics and spectra of surface-layer variables only. We validated our detection method with boundary-layer measurements. Furthermore, we confirm that Monin–Obukhov similarity functions fit

  12. 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

  13. 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.

  14. Surface Phenomena During Plasma-Assisted Atomic Layer Etching of SiO2.

    Science.gov (United States)

    Gasvoda, Ryan J; van de Steeg, Alex W; Bhowmick, Ranadeep; Hudson, Eric A; Agarwal, Sumit

    2017-09-13

    Surface phenomena during atomic layer etching (ALE) of SiO 2 were studied during sequential half-cycles of plasma-assisted fluorocarbon (CF x ) film deposition and Ar plasma activation of the CF x film using in situ surface infrared spectroscopy and ellipsometry. Infrared spectra of the surface after the CF x deposition half-cycle from a C 4 F 8 /Ar plasma show that an atomically thin mixing layer is formed between the deposited CF x layer and the underlying SiO 2 film. Etching during the Ar plasma cycle is activated by Ar + bombardment of the CF x layer, which results in the simultaneous removal of surface CF x and the underlying SiO 2 film. The interfacial mixing layer in ALE is atomically thin due to the low ion energy during CF x deposition, which combined with an ultrathin CF x layer ensures an etch rate of a few monolayers per cycle. In situ ellipsometry shows that for a ∼4 Å thick CF x film, ∼3-4 Å of SiO 2 was etched per cycle. However, during the Ar plasma half-cycle, etching proceeds beyond complete removal of the surface CF x layer as F-containing radicals are slowly released into the plasma from the reactor walls. Buildup of CF x on reactor walls leads to a gradual increase in the etch per cycle.

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    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...

  16. 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.

  17. 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

  18. 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.

  19. [A surface reacted layer study of titanium-zirconium alloy after dental casting].

    Science.gov (United States)

    Zhang, Y; Guo, T; Li, Z; Li, C

    2000-10-01

    To investigate the influence of the mold temperature on the surface reacted layer of Ti-Zr alloy castings. Ti-Zr alloy was casted into a mold which was made of a zircon (ZrO2.SiO2) for inner coating and a phosphate-bonded material for outer investing with a casting machine (China) designed as vacuum, pressure and centrifuge. At three mold temperatures (room temperature, 300 degrees C, 600 degrees C) the Ti-Zr alloy was casted separately. The surface roughness of the castings was calculated by instrument of smooth finish (China). From the surface to the inner part the Knoop hardness and thickness in reacted layer of Ti-Zr alloy casting was measured. The structure of the surface reacted layer was analysed by SEM. Elemental analyses of the interfacial zone of the casting was made by element line scanning observation. The surface roughness of the castings was increased significantly with the mold temperature increasing. At a higher mold temperature the Knoop hardness of the reactive layer was increased. At the three mold temperature the outmost surface was very hard, and microhardness data decreased rapidly where they reached constant values. The thickness was about 85 microns for castings at room temperature and 300 degrees C, 105 microns for castings at 600 degrees C. From the SEM micrograph of the Ti-Zr alloy casting, the surface reacted layer could be divided into three different layers. The first layer was called non-structure layer, which thickness was about 10 microns for room temperature group, 20 microns for 300 degrees C and 25 microns for 600 degrees C. The second layer was characterized by coarse-grained acicular crystal, which thickness was about 50 microns for three mold temperatures. The third layer was Ti-Zr alloy. The element line scanning showed non-structure layer with higher level of element of O, Al, Si and Zr, The higher the mold temperature during casting, the deeper the Si permeating and in the second layer the element Si could also be found

  20. 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.)

  1. Influence of laser alloyed layer of carbon steel with tantalum on the structure and surface layer properties

    International Nuclear Information System (INIS)

    Woldan, A.; Kusinski, J.; Kac, S.

    1999-01-01

    The paper describes the microstructure and properties (chemical composition and microhardness) of the surface laser alloyed layer with tantalum. The surface alloyed zones varied in microstructure, zones depth and width, as well as Ta content according to the thickness of the coated layer, bonding paint type and process parameters (power and scanning velocity). The electron microprobe analysis of melts showed that higher tantalum content in the melted zone resulted from the thicker original Ta coating as well as slower scanning velocity. Scanning electron microscopy examinations show that dendritic structure of the melted zone becomes evident when carbon was used as one of the components of the binder, while structure is typically martensitic when silicon containing binder was used for powder deposition. Samples covered with Ta and carbon containing binder showed after laser alloying higher hardness than in case of using silicon containing binder. (author)

  2. Dry Deposition, Surface Production and Dynamics of Aerosols in the Marine Boundary Layer

    DEFF Research Database (Denmark)

    Fairall, C.W.; Larsen, Søren Ejling

    1984-01-01

    A model of downward aerosol panicle flux characterized by dry deposition velocity, Vd, due to Slinn and Slinn (1980) is generalized to the case of nonzero surface concentration (absorbing surface with a surface source). A more general expression for the flux at some reference height is developed ...... produced as droplets at the surface and ‘continental’ background aerosols brought into the boundary layer at the top by entrainment and gravitational settling. Estimates of Si are provided....

  3. Methane oxidation and methane fluxes in the ocean surface layer and deep anoxic waters

    Science.gov (United States)

    Ward, B. B.; Kilpatrick, K. A.; Novelli, P. C.; Scranton, M. I.

    1987-01-01

    Measured biological oxidation rates of methane in near-surface waters of the Cariaco Basin are compared with the diffusional fluxes computed from concentration gradients of methane in the surface layer. Methane fluxes and oxidation rates were investigated in surface waters, at the oxic/anoxic interface, and in deep anoxic waters. It is shown that the surface-waters oxidation of methane is a mechanism which modulates the flux of methane from marine waters to the atmosphere.

  4. Marine Atmospheric Surface Layer and Its Application to Electromagnetic Wave Propagation

    Science.gov (United States)

    Wang, Q.

    2015-12-01

    An important application of the atmospheric surface layer research is to characterize the near surface vertical gradients in temperature and humidity in order to predict radar and radio communication conditions in the environment. In this presentation, we will give an overview of a new research initiative funded under the Office of Naval Research (ONR) Multi-University Research Initiative (MURI): the Coupled Air-Sea Processes and EM Ducting Research (CASPER). The objective is to fully characterize the marine atmospheric boundary layer (MABL) as an electromagnetic (EM) propagation environment with the emphasis of spatial and temporal heterogeneities and surface wave/swell effects, both of which contravene the underlying assumptions of Monin-Obukhov Similarity Theory (MOST) used in coupled environmental forecast models. Furthermore, coastal variability in the inversion atop the MABL presents a challenge to forecast models and also causes practical issues in EM prediction models. These issues are the target of investigation of CASPER. CASPER measurement component includes two major field campaigns: CASPER-East (2015 Duck, NC) and CASPER-West (2018 southern California). This presentation will show the extensive measurements to be made during the CASPER -East field campaign with the focus on the marine atmospheric surface layer measurements with two research vessels, two research aircraft, surface flux buoy, wave gliders, ocean gliders, tethered balloons, and rawinsondes. Unlike previous research on the marine surface layer with the focus on surface fluxes and surface flux parameterization, CASPER field campaigns also emphasize of the surface layer profiles and the validation of the surface layer flux-profile relationship originally derived over land surfaces. Results from CASPER pilot experiment and preliminary results from CASPER-East field campaign will be discussed.

  5. Recycling inflow method for simulations of spatially evolving turbulent boundary layers over rough surfaces

    Science.gov (United States)

    Yang, Xiang I. A.; Meneveau, Charles

    2016-01-01

    The technique by Lund et al. to generate turbulent inflow for simulations of developing boundary layers over smooth flat plates is extended to the case of surfaces with roughness elements. In the Lund et al. method, turbulent velocities on a sampling plane are rescaled and recycled back to the inlet as inflow boundary condition. To rescale mean and fluctuating velocities, appropriate length scales need be identified and for smooth surfaces, the viscous scale lν = ν/uτ (where ν is the kinematic viscosity and uτ is the friction velocity) is employed for the inner layer. Different from smooth surfaces, in rough wall boundary layers the length scale of the inner layer, i.e. the roughness sub-layer scale ld, must be determined by the geometric details of the surface roughness elements and the flow around them. In the proposed approach, it is determined by diagnosing dispersive stresses that quantify the spatial inhomogeneity caused by the roughness elements in the flow. The scale ld is used for rescaling in the inner layer, and the boundary layer thickness δ is used in the outer region. Both parts are then combined for recycling using a blending function. Unlike the blending function proposed by Lund et al. which transitions from the inner layer to the outer layer at approximately 0.2δ, here the location of blending is shifted upwards to enable simulations of very rough surfaces in which the roughness length may exceed the height of 0.2δ assumed in the traditional method. The extended rescaling-recycling method is tested in large eddy simulation of flow over surfaces with various types of roughness element shapes.

  6. Design of Matched Absorbing Layers for Surface Plasmon-Polaritons

    Directory of Open Access Journals (Sweden)

    Sergio de la Cruz

    2012-01-01

    Full Text Available We describe a procedure for designing metal-metal boundaries for the strong attenuation of surface plasmon-polaritons without the introduction of reflections or scattering effects. Solutions associated with different sets of matching materials are found. To illustrate the results and the consequences of adopting different solutions, we present calculations based on an integral equation formulation for the scattering problem and the use of a nonlocal impedance boundary condition.

  7. 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

    ) 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......Thermo-reactive deposition and diffusion (TRD) and boriding are thermochemical processes that result in very high surface hardness by conversion of the surface into carbides/nitrides and borides, respectively. These treatments offer significant advantages in terms of hardness, adhesion, tribo...... 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...

  8. X-ray study of surface layers of tungsten monocrystals after electroerosion machining

    International Nuclear Information System (INIS)

    Aleshina, S.A.; Baranov, Yu.V.; Smirnov, I.S.; Marchuk, A.I.

    1981-01-01

    The presence of polycrystal surface layer, approximately 10 μm thick in subjacent layers and the presence of highly developed block structure which is the result of high-temperature effect of electroerosion machining are detected. Angles of disorientation between blocks, which constitute tens of angular minutes, are evaluated using the method of X-ray topography. According to broadening of profile of X-ray diffraction lines analysis of fine crystal structure of the surface layers is conducted. It is shown that the broadening of diffraction lines is mainly connected with the presence of coherent scat-- tering regions

  9. 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.

  10. 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.

  11. 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.

  12. Control of Alq3 wetting layer thickness via substrate surface functionalization.

    Science.gov (United States)

    Tsoi, Shufen; Szeto, Bryan; Fleischauer, Michael D; Veinot, Jonathan G C; Brett, Michael J

    2007-06-05

    The effects of substrate surface energy and vapor deposition rate on the initial growth of porous columnar tris(8-hydroxyquinoline)aluminum (Alq3) nanostructures were investigated. Alq3 nanostructures thermally evaporated onto as-supplied Si substrates bearing an oxide were observed to form a solid wetting layer, likely caused by an interfacial energy mismatch between the substrate and Alq3. Wetting layer thickness control is important for potential optoelectronic applications. A dramatic decrease in wetting layer thickness was achieved by depositing Alq3 onto alkyltrichlorosilane-derivatized Si/oxide substrates. Similar effects were noted with increasing deposition rates. These two effects enable tailoring of the wetting layer thickness.

  13. 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

  14. Tribological Characteristic of Titanium Alloy Surface Layers Produced by Diode Laser Gas Nitriding

    Directory of Open Access Journals (Sweden)

    Lisiecki A.

    2016-06-01

    Full Text Available In order to improve the tribological properties of titanium alloy Ti6Al4V composite surface layers Ti/TiN were produced during laser surface gas nitriding by means of a novel high power direct diode laser with unique characteristics of the laser beam and a rectangular beam spot. Microstructure, surface topography and microhardness distribution across the surface layers were analyzed. Ball-on-disk tests were performed to evaluate and compare the wear and friction characteristics of surface layers nitrided at different process parameters, base metal of titanium alloy Ti6Al4V and also the commercially pure titanium. Results showed that under dry sliding condition the commercially pure titanium samples have the highest coefficient of friction about 0.45, compared to 0.36 of titanium alloy Ti6Al4V and 0.1-0.13 in a case of the laser gas nitrided surface layers. The volume loss of Ti6Al4V samples under such conditions is twice lower than in a case of pure titanium. On the other hand the composite surface layer characterized by the highest wear resistance showed almost 21 times lower volume loss during the ball-on-disk test, compared to Ti6Al4V samples.

  15. Surface passivation of InP solar cells with InAlAs layers

    Science.gov (United States)

    Jain, Raj K.; Flood, Dennis J.; Landis, Geoffrey A.

    1993-01-01

    The efficiency of indium phosphide solar cells is limited by high values of surface recombination. The effect of a lattice-matched In(0.52)Al(0.48)As window layer material for InP solar cells, using the numerical code PC-1D is investigated. It was found that the use of InAlAs layer significantly enhances the p(+)n cell efficiency, while no appreciable improvement is seen for n(+)p cells. The conduction band energy discontinuity at the heterojunction helps in improving the surface recombination. An optimally designed InP cell efficiency improves from 15.4 percent to 23 percent AMO for a 10 nm thick InAlAs layer. The efficiency improvement reduces with increase in InAlAs layer thickness, due to light absorption in the window layer.

  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. Torsional surface waves in an inhomogeneous layer over a gravitating anisotropic porous half-space

    International Nuclear Information System (INIS)

    Gupta, Shishir; Pramanik, Abhijit

    2015-01-01

    The present work aims to deal with the propagation of torsional surface wave in an inhomogeneous layer over a gravitating anisotropic porous half space. The inhomogeneous layer exhibits the inhomogeneity of quadratic type. In order to show the effect of gravity the equation for the velocity of torsional wave has been obtained. It is also observed that for a layer over a homogeneous half space without gravity, the torsional surface wave does not propagate. An attempt is also made to assess the possible propagation of torsional surface waves in that medium in the absence of the upper layer. The effects of inhomogeneity factors and porosity on the phase velocity are depicted by means of graphs. (paper)

  18. 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.

  19. 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.

  20. Compensation of propagation loss of surface plasmon polaritons with a finite-thickness dielectric gain layer

    International Nuclear Information System (INIS)

    Zhang, Xin; Liu, Haitao; Zhong, Ying

    2012-01-01

    We theoretically study the compensation of propagation loss of surface plasmon polaritons (SPPs) with the use of a finite-thickness dielectric layer with optical gain. The impacts of the gain coefficient, the gain-layer thickness and the wavelength on the loss compensation and the field distribution of the SPP mode are systematically explored with a fully vectorial method. Abnormal behaviors for the loss compensation as the gain-layer thickness increases are found and explained. Critical values of the gain coefficient and of the corresponding gain-layer thickness for just compensating the propagation loss are provided. Our results show that as the SPP propagation loss is fully compensated with a gain coefficient at a reasonably low level, the gain layer is still thin enough to ensure a large exterior SPP field at the gain-layer/air interface, which is important for achieving a strong light–matter interaction for applications such as bio-chemical sensing. (paper)

  1. Polyethylene imine/graphene oxide layer-by-layer surface functionalization for significantly improved limit of detection and binding kinetics of immunoassays on acrylate surfaces.

    Science.gov (United States)

    Miyazaki, Celina M; Mishra, Rohit; Kinahan, David J; Ferreira, Marystela; Ducrée, Jens

    2017-10-01

    Antibody immobilization on polymeric substrates is a key manufacturing step for microfluidic devices that implement sample-to-answer automation of immunoassays. In this work, a simple and versatile method to bio-functionalize poly(methylmethacrylate) (PMMA), a common material of such "Lab-on-a-Chip" systems, is proposed; using the Layer-by-Layer (LbL) technique, we assemble nanostructured thin films of poly(ethylene imine) (PEI) and graphene oxide (GO). The wettability of PMMA surfaces was significantly augmented by the surface treatment with (PEI/GO) 5 film, with an 81% reduction of the contact angle, while the surface roughness increased by 600%, thus clearly enhancing wettability and antibody binding capacity. When applied to enzyme-linked immunosorbent assays (ELISAs), the limit of detection of PMMA surface was notably improved from 340pgmL -1 on commercial grade polystyrene (PS) and 230pgmL -1 on plain PMMA surfaces to 130pgmL -1 on (PEI/GO) 5 treated PMMA. Furthermore, the accelerated antibody adsorption kinetics on the LbL films of GO allowed to substantially shorten incubation times, e.g. for anti-rat IgG adsorption from 2h down to 15min on conventional and treated surfaces, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Can coarse surface layers in gravel-bedded rivers be mobilized by finer gravel bedload?

    Science.gov (United States)

    Venditti, J. G.; Dietrich, W. E.; Nelson, P. A.; Wydzga, M. A.; Fadde, J.; Sklar, L.

    2005-12-01

    In response to reductions in sediment supply, gravel-bed rivers undergo a coarsening of the sediments that comprise the river's bed and, over some longer time scale, a river's grade may also be reduced as sediments are depleted from upstream reaches. Coarse, degraded river reaches are commonly observed downstream of dams across the Western United States. Following dam closure, these riverbeds become immobile under the altered flow and sediment supply regimes, leading to a reduction in the available salmon spawning and rearing habitat. Gravel augmentation to these streams is now common practice. This augmentation is typically seen as resurfacing the static coarse bed. As an alternative, we propose that the addition of appropriately finer gravels to these channels may be capable of mobilizing an otherwise immobile coarse surface layer, creating the potential to release fine material trapped beneath the surface. A series of laboratory experiments are being undertaken to test this hypothesis in a 30 m long and 0.86 m wide gravel-bedded flume channel using a constant discharge and a unimodal bed sediment with a median grain size of 8 mm and no sand present. The channel width-to-depth ratio of ~4 suppresses the development of lateral topography and allows us to focus on grain-to-grain interactions. Experiments proceed by maintaining a constant sediment feed until an equilibrium grade and transport rate are established, starving the flume of sediment for at least 24 hours, and then adding narrowly graded gravel over a period of one to two hours at a rate that is ~4x the bedload rate observed prior to terminating the sediment supply. The bed prior to sediment addition has an armor median grain size that is typically twice that of the subsurface and feed size distribution. The volume and median grain size of the resulting pulses are varied. Pulses move downstream rapidly with well-defined fronts in the form of bedload sheets and cause peaks in the sediment flux

  3. Antiferromagnetic MnN layer on the MnGa(001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero-Sánchez, J., E-mail: guerrero@cnyn.unam.mx; Takeuchi, Noboru

    2016-12-30

    Highlights: • A ferromagnetic Gallium terminated surface is stable before N incorporation. • After N incorporation, an antiferromagnetic MnN layer becomes stable in a wide range of chemical potential. • Spin density distribution shows an antiferromagnetic/ferromagnetic (MnN/MnGa) arrangement at the surface. - Abstract: Spin polarized first principles total energy calculations have been applied to study the stability and magnetic properties of the MnGa(001) surface and the formation of a topmost MnN layer with the deposit of nitrogen. Before nitrogen adsorption, surface formation energies show a stable gallium terminated ferromagnetic surface. After incorporation of nitrogen atoms, the antiferromagnetic manganese terminated surface becomes stable due to the formation of a MnN layer (Mn-N bonding at the surface). Spin density distribution shows a ferromagnetic/antiferromagnetic arrangement in the first surface layers. This thermodynamically stable structure may be exploited to growth MnGa/MnN magnetic heterostructures as well as to look for exchange biased systems.

  4. Laser study of phase changes in the surface layer of porous materials

    International Nuclear Information System (INIS)

    Wojtatowicz, T W

    2001-01-01

    The paper presents some aspects of the use of interference patterns observed upon reflection of laser radiation from the surface of a porous solid (laser speckles) for the study of moisture condensation in the near-surface layer. (interaction of laser radiation with matter. laser plasma)

  5. 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.

  6. A mechanical model for surface layer formation on self-lubricating ceramic composites

    NARCIS (Netherlands)

    Song, Jiupeng; Valefi, Mahdiar; de Rooij, Matthias B.; Schipper, Dirk J.

    2010-01-01

    To predict the thickness of a self-lubricating layer on the contact surface of ceramic composite material containing a soft phase during dry sliding test, a mechanical model was built to calculate the material transfer of the soft second phase in the composite to the surface. The tribological test,

  7. Laser-induced oxidation of titanium substrate: Analysis of the physicochemical structure of the surface and sub-surface layers

    Energy Technology Data Exchange (ETDEWEB)

    Antończak, Arkadiusz J., E-mail: arkadiusz.antonczak@pwr.edu.pl [Laser and Fiber Electronics Group, Faculty of Electrical Engineering, Wroclaw University of Technology, Wyb. Wyspianskiego 27, 50-370 Wroclaw (Poland); Skowroński, Łukasz; Trzcinski, Marek [Institute of Mathematics and Physics, University of Technology and Life Sciences, Kaliskiego 7, 85-789 Bydgoszcz (Poland); Kinzhybalo, Vasyl V. [Wroclaw Research Centre EIT+, Stabłowicka 147, 54-066 Wrocław (Poland); Institute of Low Temperature and Structure Research, Okólna 2, 50-422 Wrocław (Poland); Łazarek, Łukasz K.; Abramski, Krzysztof M. [Laser and Fiber Electronics Group, Faculty of Electrical Engineering, Wroclaw University of Technology, Wyb. Wyspianskiego 27, 50-370 Wroclaw (Poland)

    2015-01-15

    Highlights: • Chemical structure of the films induced by laser on titanium surface was analyzed. • It was shown that outer layer of this films consist of oxides doped with nitrogen. • The optical properties of the laser-induced oxynitride films were characterized. • We found that the films demonstrated significant absorption in the band of 300–580 nm. • The morphology of the layers as a function of the laser fluence was investigated. - Abstract: This paper presents the results of the analysis of the complex chemical structure of the layers made on titanium in the process of the heating of its surfaces in an atmospheric environment, by irradiating samples with a nanosecond-pulsed laser. The study was carried out for electroplated, high purity, polycrystalline titanium substrates using a Yb:glass fiber laser. All measurements were made for samples irradiated in a broad range of accumulated fluence, below the ablation threshold. It has been determined how the complex index of refraction of both the oxynitride layers and the substrate vary as a function of accumulated laser fluence. It was also shown that the top layer of the film produced on titanium, which is transparent, is not a pure TiO{sub 2} as had been supposed before. The XPS and XRD analyses confirmed the presence of nitrogen compounds and the existence of nonstoichiometric compounds. By sputtering of the sample's surface using an Ar{sup +} ion gun, the changes in the concentration of individual elements as a function of the layer's cross-section were determined. Lastly, an analysis of the surface morphology has also been carried out, explaining why the layers crack and exfoliate from their substrate.

  8. Modification on surface oxide layer structure and surface morphology of niobium by gas cluster ion beam treatments

    International Nuclear Information System (INIS)

    Wu, A.T.; Swenson, D.R.; Insepov, Z.

    2010-01-01

    Recently, it was demonstrated that significant reductions in field emission on Nb surfaces could be achieved by means of a new surface treatment technique called gas cluster ion beam (GCIB). Further study as shown in this paper revealed that GCIB treatments could modify surface irregularities and remove surface asperities leading to a smoother surface finish as demonstrated through measurements using a 3D profilometer, an atomic force microscope, and a scanning electron microscope. These experimental observations were supported by computer simulation via atomistic molecular dynamics and a phenomenological surface dynamics. Measurements employing a secondary ion mass spectrometry found that GCIB could also alter Nb surface oxide layer structure. Possible implications of the experimental results on the performance of Nb superconducting radio frequency cavities treated by GCIB will be discussed. First experimental results on Nb single cell superconducting radio frequency cavities treated by GCIB will be reported.

  9. Measurements of surface layer of the articular cartilage using microscopic techniques

    International Nuclear Information System (INIS)

    Ryniewicz, A. M; Ryniewicz, W.; Ryniewicz, A.; Gaska, A.

    2010-01-01

    The articular cartilage is the structure that directly cooperates tribologically in biobearing. It belongs to the connective tissues and in the joints it assumes two basic forms: hyaline cartilage that builds joint surfaces and fibrocartilage which may create joint surfaces. From this fibrocartilage are built semilunar cartilage and joint disc are built as well. The research of articular cartilage have been done in macro, micro and nano scale. In all these measurement areas characteristic features occur which can identify biobearing tribology. The aim of the research was the identification of surface layer of articular cartilage by means of scanning electron microscopy (SEM) and atom force microscopy (AFM) and the analysis of topography of these layers. The material used in the research of surface layer was the animal articular cartilage: hyaline cartilage and fibrocartilage.

  10. Measurements of surface layer of the articular cartilage using microscopic techniques

    Science.gov (United States)

    Ryniewicz, A. M.; Ryniewicz, A.; Ryniewicz, W.; Gaska, A.

    2010-07-01

    The articular cartilage is the structure that directly cooperates tribologically in biobearing. It belongs to the connective tissues and in the joints it assumes two basic forms: hyaline cartilage that builds joint surfaces and fibrocartilage which may create joint surfaces. From this fibrocartilage are built semilunar cartilage and joint disc are built as well. The research of articular cartilage have been done in macro, micro and nano scale. In all these measurement areas characteristic features occur which can identify biobearing tribology. The aim of the research was the identification of surface layer of articular cartilage by means of scanning electron microscopy (SEM) and atom force microscopy (AFM) and the analysis of topography of these layers. The material used in the research of surface layer was the animal articular cartilage: hyaline cartilage and fibrocartilage.

  11. 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)

  12. Thickened boundary layer theory for air film drag reduction on a van body surface

    Science.gov (United States)

    Xie, Xiaopeng; Cao, Lifeng; Huang, Heng

    2018-05-01

    To elucidate drag reduction mechanism on a van body surface under air film condition, a thickened boundary layer theory was proposed and a frictional resistance calculation model of the van body surface was established. The frictional resistance on the van body surface was calculated with different parameters of air film thickness. In addition, the frictional resistance of the van body surface under the air film condition was analyzed by computational fluid dynamics (CFD) simulation and different air film states that influenced the friction resistance on the van body surface were discussed. As supported by the CFD simulation results, the thickened boundary layer theory may provide reference for practical application of air film drag reduction on a van body surface.

  13. Helicity and potential vorticity in the surface boundary layer turbulence

    Science.gov (United States)

    Chkhetiani, Otto; Kurgansky, Michael; Koprov, Boris; Koprov, Victor

    2016-04-01

    An experimental measurement of all three components of the velocity and vorticity vectors, as well as the temperature and its gradient, and potential vorticity, has been developed using four acoustic anemometers. Anemometers were placed at vertices of a tetrahedron, the horizontal base of which was a rectangular triangle with equal legs, and the upper point was exactly above the top of the right angle. The distance from the surface to the tetrahedron its base was 5.5 m, and the lengths of legs and a vertical edge were 5 m. The measurements were carried out of total duration near 100 hours both in stable and unstable stratification conditions (at the Tsimlyansk Scientific Station in a uniform area of virgin steppe 700 x 650 m, August 2012). A covariance-correlation matrix for turbulent variations in all measured values has been calculated. In the daytime horizontal and vertical components of the helicity are of the order of -0.03 and +0.01 m s-2, respectively. The nighttime signs remain unchanged, but the absolute values are several times smaller. It is confirmed also by statistics of a relative helicity. The cospectra and spectral correlation coefficients have been calculated for all helicity components. The time variations in the components of "instantaneous" relative helicity and potential vorticity are considered. Connections of helicity with Monin-Obukhov length and the wind vertical profile structure are discussed. This work was supported by the Russian Science Foundation (Project No 14-27-00134).

  14. 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.

  15. Surface layers in the 4A group metals with implanted silicon ions

    International Nuclear Information System (INIS)

    Kovneristyj, Yu.K.; Vavilova, V.V.; Krasnopevtsev, V.V.; Galkin, L.N.; Kudyshev, A.N.; Klechkovskaya, V.V.

    1987-01-01

    A study was made on the change of structure and phase composition of fine near the surface layers of 4A group metals (Hf, Zr, Ti) during ion Si implantation and successive thermal annealing at elevated temperatures. Implantation of Si + ions with 30 or 16 keV energy in Ti, Zr and Hf at room temperature results to amorphization of metal surface layer. The surface hafnium and titanium layer with implanted Si atoms due to interaction with residual atmosphere of oxygen turns during annealing at 870 K to amorphous solid solution of HfO 2m or TiO 2 with Si, preventing further metal oxidation; layers of amorphous alloy are characterized by thermal stability up to 1270 K. Oxidation of the surface amorphous layer in residual oxygen atmosphere and its crystallization in ZrO 2 take place in result of Zr annealing with implanted Si ions at temperature not exceeding 870 K. Similar phenomena are observed in the case of hafnium with implanted oxygen ions or small dose of silicon ions. Thermal stability of amorphous layers produced during ion implantation of Si in Ti, Zr and Hf corresponds to scale resistance of monolithic alloys in Ti-Si, Zr-Si and Hf-Si systems

  16. Dynamic Dispersal of Surface Layer Biofilm Induced by Nanosized TiO2 Based on Surface Plasmon Resonance and Waveguide.

    Science.gov (United States)

    Zhang, Peng; Guo, Jin-Song; Yan, Peng; Chen, You-Peng; Wang, Wei; Dai, You-Zhi; Fang, Fang; Wang, Gui-Xue; Shen, Yu

    2018-05-01

    Pollutant degradation is present mainly in the surface layer of biofilms, and the surface layer is the most vulnerable to impairment by toxic pollutants. In this work, the effects of nanosized TiO 2 (n-TiO 2 ) on the average thicknesses of Bacillus subtilis biofilm and on bacterial attachment on different surfaces were investigated. The binding mechanism of n-TiO 2 to the cell surface was also probed. The results revealed that n-TiO 2 caused biofilm dispersal and the thicknesses decreased by 2.0 to 2.6 μm after several hours of exposure. The attachment abilities of bacteria with extracellular polymeric substances (EPS) on hydrophilic surfaces were significantly reduced by 31% and 81% under 10 and 100 mg/liter of n-TiO 2 , respectively, whereas those of bacteria without EPS were significantly reduced by 43% and 87%, respectively. The attachment abilities of bacteria with and without EPS on hydrophobic surfaces were significantly reduced by 50% and 56%, respectively, under 100 mg/liter of n-TiO 2 The results demonstrated that biofilm dispersal can be attributed to the changes in the cell surface structure and the reduction of microbial attachment ability. IMPORTANCE Nanoparticles can penetrate into the outer layer of biofilm in a relatively short period and can bind onto EPS and bacterial surfaces. The current work probed the effects of nanosized TiO 2 (n-TiO 2 ) on biofilm thickness, bacterial migration, and surface properties of the cell in the early stage using the surface plasmon resonance waveguide mode. The results demonstrated that n-TiO 2 decreased the adhesive ability of both cell and EPS and induced bacterial migration and biofilm detachment in several hours. The decreased adhesive ability of microbes and EPS worked against microbial aggregation, reducing the effluent quality in the biological wastewater treatment process. Copyright © 2018 American Society for Microbiology.

  17. A quality-control procedure for surface temperature and surface layer inversion in the XBT data archive from the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Pankajakshan, T.; Ghosh, A.K.; Pattanaik, J.; Ratnakaran, L.

    and surface layer temperature inversion. XBT surface temperatrues (XST) are compared with the surface temperature from simultaneous CTD observations from four cruises and the former were found to be erroneous in a number of stations. XSTs are usually corrected...

  18. Dissolution model for a glass having an adherent insoluble surface layer

    International Nuclear Information System (INIS)

    Harvey, K.B.; Larocque, C.A.B.

    1990-01-01

    Waste form glasses that contain substantial quantities of iron, manganese, and aluminum oxides, such as the Savannah River SRL TDS-131 glass, form a thick, hydrated surface layer when placed in contact with water. The dissolution of such a glass has been modeled with the Savannah River Model. The authors showed previously that the equations of the Savannah River Model could be fitted to published experimental data if a time-dependent diffusion coefficient was assumed for species of diffusing through the surface layer. The Savannah River Model assumes that all of the material dissolved from the glass enters solution, whereas it was observed that substantial quantities of material were retained in the surface layer. An alternative model, presented contains a mass balance equation that allows material either to enter solution or to be retained in the surface layer. It is shown that the equations derived using this model can be fitted to the published experimental data assuming a constant diffusion coefficient for species diffusing through the surface layer

  19. 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.

  20. 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.

  1. 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.

  2. Bloch Surface Waves Using Graphene Layers: An Approach toward In-Plane Photodetectors

    Directory of Open Access Journals (Sweden)

    Richa Dubey

    2018-03-01

    Full Text Available A dielectric multilayer platform was investigated as a foundation for two-dimensional optics. In this paper, we present, to the best of our knowledge, the first experimental demonstration of absorption of Bloch surface waves in the presence of graphene layers. Graphene is initially grown on a Cu foil via Chemical Vapor Deposition and transferred layer by layer by a wet-transfer method using poly(methyl methacrylate, (PMMA. We exploit total internal reflection configuration and multi-heterodyne scanning near-field optical microscopy as a far-field coupling method and near-field characterization tool, respectively. The absorption is quantified in terms of propagation lengths of Bloch surface waves. A significant drop in the propagation length of the BSWs is observed in the presence of graphene layers. The propagation length of BSWs in bare multilayer is reduced to 17 times shorter in presence of graphene monolayer, and 23 times shorter for graphene bilayer.

  3. XPS studies of SiO2 surface layers formed by oxygen ion implantation into silicon

    International Nuclear Information System (INIS)

    Schulze, D.; Finster, J.

    1983-01-01

    SiO 2 surface layers of 160 nm thickness formed by 16 O + ion implantation into silicon are examined by X-ray photoelectron spectroscopy measurements into the depth after a step-by-step chemical etching. The chemical nature and the thickness of the transition layer were determined. The results of the XPS measurements show that the outer surface and the bulk of the layers formed by oxygen implantation and subsequent high temperature annealing consist of SiO 2 . There is no evidence for Si or SiO/sub x/ (0 2 and Si is similar to that of thin grown oxide layers. Only its thickness is somewhat larger than in thermal oxide

  4. Duplex surface treatment of AISI 1045 steel via plasma nitriding of chromized layer

    International Nuclear Information System (INIS)

    Hakami, F.; Sohi, M. Heydarzadeh; Ghani, J. Rasizadeh

    2011-01-01

    In this work AISI 1045 steel were duplex treated via plasma nitriding of chromized layer. Samples were pack chromized by using a powder mixture consisting of ferrochromium, ammonium chloride and alumina at 1273 K for 5 h. The samples were then plasma-nitrided for 5 h at 803 K and 823 K, in a gas mixture of 75%N 2 + 25%H 2 . The treated specimens were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis and Vickers micro-hardness test. The thickness of chromized layer before nitriding was about 8 μm and it was increased after plasma nitriding. According to XRD analysis, the chromized layer was composed of chromium and iron carbides. Plasma nitriding of chromized layer resulted in the formation of chromium and iron nitrides and carbides. The hardness of the duplex layers was significantly higher than the hardness of the base material or chromized layer. The main cause of the large improvement in surface hardness was due to the formation of Cr x N and Fe x N phases in the duplex treated layers. Increasing of nitriding temperature from 803 to 823 K enhanced the formation of CrN in the duplex treated layer and increased the thickness of the nitrided layer.

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

    International Nuclear Information System (INIS)

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

    2017-01-01

    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

  6. 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

  7. Murein Hydrolase Activity in the Surface Layer of Lactobacillus acidophilus ATCC 4356▿

    OpenAIRE

    Prado Acosta, Mariano; Palomino, María Mercedes; Allievi, Mariana C.; Rivas, Carmen Sanchez; Ruzal, Sandra M.

    2008-01-01

    We describe a new enzymatic functionality for the surface layer (S-layer) of Lactobacillus acidophilus ATCC 4356, namely, an endopeptidase activity against the cell wall of Salmonella enterica serovar Newport, assayed via zymograms and identified by Western blotting. Based on amino acid sequence comparisons, the hydrolase activity was predicted to be located at the C terminus. Subsequent cloning and expression of the C-terminal domain in Bacillus subtilis resulted in the functional verificati...

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

    International Nuclear Information System (INIS)

    Sang, Jing; Aisawa, Sumio; Hirahara, Hidetoshi; Kudo, Takahiro; Mori, Kunio

    2016-01-01

    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"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"+ ion to Ag"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.

  9. 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.

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

    OpenAIRE

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

    2017-01-01

    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 stai...

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

    OpenAIRE

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

    2017-01-01

    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 st...

  12. The influence of Ni, Mo, Si, Ti on the surface alloy layer quality

    Directory of Open Access Journals (Sweden)

    A. Walasek

    2011-07-01

    Full Text Available The paper presents research results of microstructure and selected mechanical properties of alloy layer. The aim of the researches was to determine the influence of Ni, Mo, Si and Ti with high-carbon ferrochromium (added separately to pad on the alloy layer on the steel cast. Metallographic studies were made with use of light microscopy. During studies of usable properties measurements of hardness, microhardness and abrasive wear resistance of type metal-mineral for creation alloy layer were made. As thick as possible composite layer without any defects and discontinuity was required. The conducted researches allowed to take the suitable alloy addition of the pad material which improved the quality of the surface alloy layer.

  13. Methods of improvement in hardness of composite surface layer on cast steel

    Directory of Open Access Journals (Sweden)

    J. Szajnar

    2008-08-01

    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 founding process a composite surface layer on the basis of Fe-Cr-C alloy and next its remelting with use of welding technology TIG – Tungsten Inert Gas. Technology of composite surface layer guarantee mainly increase in hardness and abrasive wear resistance of cast steel castings on machine elements. This technology can be competition for generally applied welding technology (surfacing by welding and thermal spraying. However the results of studies show, that is possible to connection of both methods founding and welding of surface hardening of cast steel castings. In range of experimental plan was made test castings with composite surface layer, which next were remelted with energy 0,8 and 1,6 kJ/cm. Usability for industrial applications of test castings was estimated by criterion of hardness and abrasive wear resistance of type metal-mineral.

  14. IMPACT OF VIBRATORY AND ROTATIONAL SHOT PEENING ONTO SELECTED PROPERTIES OF TITANIUM ALLOY SURFACE LAYER

    Directory of Open Access Journals (Sweden)

    Kazimierz Zaleski

    2014-06-01

    Full Text Available This study presents the results of tests on impact of vibratory and rotational shot peening of the Ti6A12Mo2Cr titanium alloy onto the processed object surface roughness and surface layer microhardness. The external surfaces of ring-shaped samples were shot peened. The preceding process consisted of turning with a cubic boron nitride blade knife. Steel beads, having a diameter of 6 mm, were used as a processing medium. The variable parameters of shot peening were vibrator amplitude and shot peening time. The range of recommended technological parameters for vibratory and rotational shot peening was determined. As a result of shot peening, the surface roughness could be reduced by approximately 4 times and the surface layer could be hardened to the depth of approximately 0.4 mm.

  15. Strengthening of the RAFMS RUSFER-EK181 through nano structuring surface layers

    Energy Technology Data Exchange (ETDEWEB)

    Panin, A.; Melnikova, E.A. [Tomsk State Univ., lnstitute of Strength Physics and Materials Science, SB, RAS (Russian Federation); Chernov, V.M. [Bochvar Institute of Inorganic Materials, Moscow (Russian Federation); Leontieva-Smirnova, M.V. [A.A. Bochvar Research Institute of Inorganic Materials, Moscow (Russian Federation)

    2007-07-01

    Full text of publication follows: Surface nano-structuring increases yield point and strength of the reduced activation ferritic-martensitic steel (RAFMS ) RUSREF - EK181. Ultrasonic impact treatment was used to produce a nano-structure within the surface layers of the specimens. Using scanning tunnelling microscope reveals a new mechanism of mesoscale-level plastic deformation of nano-structured surface layers of the RAFMS RUSREF - EK181 as doubled spirals of localised-plastic deformation meso-bands. A linear dependence of their sizes on thickness of strengthened layer was obtained. The effect of localised deformation meso-bands on macro-mechanical properties of a material was demonstrated. A certain combination of thermal and mechanical treatment as well as optimum proportion of nano-structured surface layer thickness to thickness of a whole specimen are necessary to achieve maximum strength values. Tests performed at high temperatures in the range from 20 to 700 deg. C shows efficiency of the surface hardening of the RAFMS RUSREF - EK181. The effect of nano-structured surface layer on the character of plastic deformation and mechanical properties of the RAFMS RUSREF - EK181 was considered in the framework of a multilevel model in which loss of shear stability and generation of structural defects occur self-consistently at various scale levels such as nano-, micro-, meso-, and macro-Chessboard like distribution of stresses and misfit deformations was theoretical and experimentally shown to appear at the 'nano-structured surface layer - bulk of material' interface. Zones of compressive normal stresses alternates with zones of tensile normal stresses as on a chessboard. Plastic shear can generate only within local zones of tensile normal stresses. Critical meso-volume of non-equilibrium states required for local structure-phase transformation can be formed within these zones. Whereas within the zones of compressive normal stresses acting from both

  16. 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...

  17. 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.

  18. Method for manufacturing a solar cell with a surface-passivating dielectric double layer, and corresponding solar cell

    NARCIS (Netherlands)

    2014-01-01

    We will describe a solar cell with a Dielektrikumdoppelschicht and a method for their preparation. It comprises a first dielectric layer (3) containing aluminum oxide or consisting of alumina, and a second, hydrogen-containing dielectric layer (5) is produced by sequential vapor deposition, whereby

  19. 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.

  20. Corrosion product layers on magnesium alloys AZ31 and AZ61: Surface chemistry and protective ability

    International Nuclear Information System (INIS)

    Feliu, S.; Llorente, I.

    2015-01-01

    Highlights: • Surface chemistry of the corrosion product layers on magnesium alloys. • Influence of the type of alloy on the carbonate surface enrichment. • Relation between surface composition and protection properties. - Abstract: This paper studies the chemical composition of the corrosion product layers formed on magnesium alloys AZ31 and AZ61 following immersion in 0.6 M NaCl, with a view to better understanding their protective action. Relative differences in the chemical nature of the layers were quantified by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDX) and low-angle X-ray diffraction (XRD). Corrosion behavior was investigated by Electrochemical Impedance Spectroscopy (EIS) and hydrogen evolution measurement. An inhibitive effect from the corrosion product layers was observed from EIS, principally in the case of AZ31, as confirmed by hydrogen evolution tests. A link was found between carbonate enrichment observed by XPS in the surface of the corrosion product layer, concomitant with the increase in the protective properties observed by EIS

  1. Corrosion product layers on magnesium alloys AZ31 and AZ61: Surface chemistry and protective ability

    Energy Technology Data Exchange (ETDEWEB)

    Feliu, S., E-mail: sfeliu@cenim.csic.es; Llorente, I.

    2015-08-30

    Highlights: • Surface chemistry of the corrosion product layers on magnesium alloys. • Influence of the type of alloy on the carbonate surface enrichment. • Relation between surface composition and protection properties. - Abstract: This paper studies the chemical composition of the corrosion product layers formed on magnesium alloys AZ31 and AZ61 following immersion in 0.6 M NaCl, with a view to better understanding their protective action. Relative differences in the chemical nature of the layers were quantified by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDX) and low-angle X-ray diffraction (XRD). Corrosion behavior was investigated by Electrochemical Impedance Spectroscopy (EIS) and hydrogen evolution measurement. An inhibitive effect from the corrosion product layers was observed from EIS, principally in the case of AZ31, as confirmed by hydrogen evolution tests. A link was found between carbonate enrichment observed by XPS in the surface of the corrosion product layer, concomitant with the increase in the protective properties observed by EIS.

  2. 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.

  3. SEM Analysis of MTAD Efficacy for Smear Layer Removal from Periodontally Affected Root Surfaces

    Directory of Open Access Journals (Sweden)

    R. K. Tabor

    2011-12-01

    Full Text Available Objective: Biopure® MTAD (Dentsply Tulsa Dental, USA has been developed as a final irrigant following root canal shaping to remove intracanal smear layer. Many of the unique properties of MTAD potentially transfer to the conditioning process of tooth roots during periodontal therapy. The aim of this ex vivo studywas to evaluate the effect of MTAD on the removal of smear layer from root surfaces.Materials and Methods: Thirty two longitudinally sectioned specimens from 16 freshly extracted teeth diagnosed with advanced periodontal disease were divided into four groups. In group 1 and 2, the root surfaces were scaled using Gracey curettes. In group 3 and 4, 0.5 mm of the root surface was removed using a fissure bur. The specimens in group 1 and 3 were then irrigated by normal saline. Thespecimens in groups 2 and 4 were irrigated with Biopure MTAD.All specimens were prepared for SEM and scored according to the presence of smear layer.Results: MTAD significantly increased (P=0.001 the smear layer removal in both groups 2 and 4 compared to the associated control groups, in which only saline was used.Conclusion: MTAD increased the removal of the smear layer from periodontally affected root surfaces. Use of MTAD as a periodontal conditioner may be suggested.

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

    KAUST Repository

    Ogieglo, Wojciech; Tempelman, Kristianne; Napolitano, Simone; Benes, Nieck E.

    2018-01-01

    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.

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

    Science.gov (United States)

    Ogieglo, Wojciech; Tempelman, Kristianne; Napolitano, Simone; Benes, Nieck E

    2018-03-15

    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.

  6. Optimizing pentacene thin-film transistor performance: Temperature and surface condition induced layer growth modification.

    Science.gov (United States)

    Lassnig, R; Hollerer, M; Striedinger, B; Fian, A; Stadlober, B; Winkler, A

    2015-11-01

    In this work we present in situ electrical and surface analytical, as well as ex situ atomic force microscopy (AFM) studies on temperature and surface condition induced pentacene layer growth modifications, leading to the selection of optimized deposition conditions and entailing performance improvements. We prepared p ++ -silicon/silicon dioxide bottom-gate, gold bottom-contact transistor samples and evaluated the pentacene layer growth for three different surface conditions (sputtered, sputtered + carbon and unsputtered + carbon) at sample temperatures during deposition of 200 K, 300 K and 350 K. The AFM investigations focused on the gold contacts, the silicon dioxide channel region and the highly critical transition area. Evaluations of coverage dependent saturation mobilities, threshold voltages and corresponding AFM analysis were able to confirm that the first 3-4 full monolayers contribute to the majority of charge transport within the channel region. At high temperatures and on sputtered surfaces uniform layer formation in the contact-channel transition area is limited by dewetting, leading to the formation of trenches and the partial development of double layer islands within the channel region instead of full wetting layers. By combining the advantages of an initial high temperature deposition (well-ordered islands in the channel) and a subsequent low temperature deposition (continuous film formation for low contact resistance) we were able to prepare very thin (8 ML) pentacene transistors of comparably high mobility.

  7. 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.

  8. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-02-15

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

  10. Metal Surface Modification for Obtaining Nano- and Sub-Nanostructured Protective Layers

    Science.gov (United States)

    Ledovskykh, Volodymyr; Vyshnevska, Yuliya; Brazhnyk, Igor; Levchenko, Sergiy

    2017-03-01

    Regularities of the phase protective layer formation in multicomponent systems involving inhibitors with different mechanism of protective action have been investigated. It was shown that optimization of the composition of the inhibition mixture allows to obtain higher protective efficiency owing to improved microstructure of the phase layer. It was found that mechanism of the film formation in the presence of NaNO2-PHMG is due to deposition of slightly soluble PHMG-Fe complexes on the metal surface. On the basis of the proposed mechanism, the advanced surface engineering methods for obtaining nanoscaled and sub-nanostructured functional coatings may be developed.

  11. 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...

  12. On the sensitivity of mesoscale models to surface-layer parameterization constants

    Science.gov (United States)

    Garratt, J. R.; Pielke, R. A.

    1989-09-01

    The Colorado State University standard mesoscale model is used to evaluate the sensitivity of one-dimensional (1D) and two-dimensional (2D) fields to differences in surface-layer parameterization “constants”. Such differences reflect the range in the published values of the von Karman constant, Monin-Obukhov stability functions and the temperature roughness length at the surface. The sensitivity of 1D boundary-layer structure, and 2D sea-breeze intensity, is generally less than that found in published comparisons related to turbulence closure schemes generally.

  13. Moessbauer study of magnetic transformation of Ni3Al-(57Co+57Fe) surface layer

    International Nuclear Information System (INIS)

    Dudas, J.; Zemcik, T.

    1975-01-01

    The results of the magnetic transformation study of the Ni 3 Al-( 57 Co+ 57 Fe) surface layer by the 57 Fe Moessbauer effect in dependence on the penetration depth of ( 57 Co+ 57 Fe) are presented. These results are discussed in terms of the magnetic polarization of the Co (and Fe) atoms and the appearance of the 'giant' magnetic moment. The critical concentration of Co+Fe impurities sufficient for transformation of the originally paramagnetic surface layer into ferromagnetic at room temperature was determined to be 1.03 at.'=.. (author)

  14. 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%.

  15. 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.

  16. 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)

  17. 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.

  18. 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

  19. 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.

  20. 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

  1. Deformation characteristics of the near-surface layers of zirconia ceramics implanted with aluminum ions

    Science.gov (United States)

    Ghyngazov, S. A.; Vasiliev, I. P.; Frangulyan, T. S.; Chernyavski, A. V.

    2015-10-01

    The effect of ion treatment on the phase composition and mechanical properties of the near-surface layers of zirconium ceramic composition 97 ZrO2-3Y2O3 (mol%) was studied. Irradiation of the samples was carried out by accelerated ions of aluminum with using vacuum-arc source Mevva 5-Ru. Ion beam had the following parameters: the energy of the accelerated ions E = 78 keV, the pulse current density Ji = 4mA / cm2, current pulse duration equal τ = 250 mcs, pulse repetition frequency f = 5 Hz. Exposure doses (fluence) were 1016 и 1017 ion/cm2. The depth distribution implanted ions was studied by SIMS method. It is shown that the maximum projected range of the implanted ions is equal to 250 nm. Near-surface layers were investigated by X-ray diffraction (XRD) at fixed glancing incidence angle. It is shown that implantation of aluminum ions into the ceramics does not lead to a change in the phase composition of the near-surface layer. The influence of implanted ions on mechanical properties of ceramic near-surface layers was studied by the method of dynamic nanoindentation using small loads on the indenter P=300 mN. It is shown that in ion- implanted ceramic layer the processes of material recovery in the deformed region in the unloading mode proceeds with higher efficiency as compared with the initial material state. The deformation characteristics of samples before and after ion treatment have been determined from interpretation of the resulting P-h curves within the loading and unloading sections by the technique proposed by Oliver and Pharr. It was found that implantation of aluminum ions in the near-surface layer of zirconia ceramics increases nanohardness and reduces the Young's modulus.

  2. An Optimal Estimation Method to Obtain Surface Layer Turbulent Fluxes from Profile Measurements

    Science.gov (United States)

    Kang, D.

    2015-12-01

    In the absence of direct turbulence measurements, the turbulence characteristics of the atmospheric surface layer are often derived from measurements of the surface layer mean properties based on Monin-Obukhov Similarity Theory (MOST). This approach requires two levels of the ensemble mean wind, temperature, and water vapor, from which the fluxes of momentum, sensible heat, and water vapor can be obtained. When only one measurement level is available, the roughness heights and the assumed properties of the corresponding variables at the respective roughness heights are used. In practice, the temporal mean with large number of samples are used in place of the ensemble mean. However, in many situations the samples of data are taken from multiple levels. It is thus desirable to derive the boundary layer flux properties using all measurements. In this study, we used an optimal estimation approach to derive surface layer properties based on all available measurements. This approach assumes that the samples are taken from a population whose ensemble mean profile follows the MOST. An optimized estimate is obtained when the results yield a minimum cost function defined as a weighted summation of all error variance at each sample altitude. The weights are based one sample data variance and the altitude of the measurements. This method was applied to measurements in the marine atmospheric surface layer from a small boat using radiosonde on a tethered balloon where temperature and relative humidity profiles in the lowest 50 m were made repeatedly in about 30 minutes. We will present the resultant fluxes and the derived MOST mean profiles using different sets of measurements. The advantage of this method over the 'traditional' methods will be illustrated. Some limitations of this optimization method will also be discussed. Its application to quantify the effects of marine surface layer environment on radar and communication signal propagation will be shown as well.

  3. Change of texture, microdeformation and hardness in surface layer of TiNi alloy depending on the number of pulses of electron beam effects

    International Nuclear Information System (INIS)

    Meisner, L. L.; Meisner, S. N.; Markov, A. B.; Yakovlev, E. V.; Ozur, G. E.; Rotshtein, V. P.; Mironov, Yu. P.

    2015-01-01

    This work comprises a study of the influence of the pulse number of low-energy high-current electron beam (LEHCEB) exposure on the value and character of distribution of residual elastic stresses, texturing effects and the relationship between structural-phase states and physical and mechanical properties of the modified surface layers of TiNi alloy. LEHCEB processing of the surface of TiNi samples was carried out using a RITM-SP [3] installation. Energy density of electron beam was constant at E s = 3.9 ± 0.5 J/cm 2 ; pulse duration was 2.8 ± 0.3 μs. The number of pulses in the series was changeable, (n = 2–128). It was shown that as the result of multiple LEHCEB processing of TiNi samples, hierarchically organized multilayer structure is formed in the surface layer. The residual stress field of planar type is formed in the modified surface layer as following: in the direction of the normal to the surface the strain component ε ⊥ < 0 (compressing strain), and in a direction parallel to the surface, the strain component ε || > 0 (tensile deformation). Texturing effects and the level of residual stresses after LEHCEB processing of TiNi samples with equal energy density of electron beam (∼3.8 J/cm 2 ) depend on the number of pulses and increase with the rise of n > 10

  4. 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...... at the martensite/pearlite interface. The cracks in R350HT propagated down into the rail while those in the soft R200 returned to the surface causing only very small shallow spallation. The transverse bands had the same shape, size, orientation, location and periodicity which would be expected from grinding marks...

  5. Surface metal standards produced by ion implantation through a removable layer

    International Nuclear Information System (INIS)

    Schueler, B.W.; Granger, C.N.; McCaig, L.; McKinley, J.M.; Metz, J.; Mowat, I.; Reich, D.F.; Smith, S.; Stevie, F.A.; Yang, M.H.

    2003-01-01

    Surface metal concentration standards were produced by ion implantation and investigated for their suitability to calibrate surface metal measurements by secondary ion mass spectrometry (SIMS). Single isotope implants were made through a 100 nm oxide layer on silicon. The implant energies were chosen to place the peak of the implanted species at a depth of 100 nm. Subsequent removal of the oxide layer was used to expose the implant peak and to produce controlled surface metal concentrations. Surface metal concentration measurements by time-of-flight SIMS (TOF-SIMS) with an analysis depth of 1 nm agreed with the expected surface concentrations of the implant standards with a relative mean standard deviation of 20%. Since the TOF-SIMS relative sensitivity factors (RSFs) were originally derived from surface metal measurements of surface contaminated silicon wafers, the agreement implies that the implant standards can be used to measure RSF values. The homogeneity of the surface metal concentration was typically <10%. The dopant dose remaining in silicon after oxide removal was measured using the surface-SIMS protocol. The measured implant dose agreed with the expected dose with a mean relative standard deviation of 25%

  6. 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...

  7. Existence of a tribo-modified surface layer of BR/S-SBR elastomers reinforced with silica or carbon black

    NARCIS (Netherlands)

    Mokhtari, Milad; Schipper, Dirk J.

    2016-01-01

    The existence of a modified surface layer on top of a rubber disk, in contact with a rigid counter-surface, is still a point of discussion. In this study, we show that a modified surface layer with different mechanical properties exists. Modification of the reinforced elastomers is discussed and the

  8. Effect of complex alloying of powder materials on properties of laser melted surface layers

    International Nuclear Information System (INIS)

    Tesker, E.I.; Gur'ev, V.A.; Elistratov, V.S.; Savchenko, A.N.

    2001-01-01

    Quality and properties of laser melted surface layers produced using self-fluxing powder mixture of Ni-Cr-B-Si system and the same powders with enhanced Fe content alloyed with Co, Ti, Nb, Mo have been investigated. Composition of powder material is determined which does not cause of defect formation under laser melting and makes possible to produce a good mechanical and tribological properties of treated surface [ru

  9. Effect of the surface charge discretization on electric double layers. A Monte Carlo simulation study

    OpenAIRE

    Madurga Díez, Sergio; Martín-Molina, Alberto; Vilaseca i Font, Eudald; Mas i Pujadas, Francesc; Quesada-Pérez, Manuel

    2007-01-01

    The structure of the electric double layer in contact with discrete and continuously charged planar surfaces is studied within the framework of the primitive model through Monte Carlo simulations. Three different discretization models are considered together with the case of uniform distribution. The effect of discreteness is analyzed in terms of charge density profiles. For point surface groups,a complete equivalence with the situation of uniformly distributed charge is found if profiles are...

  10. Resistivity scaling due to electron surface scattering in thin metal layers

    Science.gov (United States)

    Zhou, Tianji; Gall, Daniel

    2018-04-01

    The effect of electron surface scattering on the thickness-dependent electrical resistivity ρ of thin metal layers is investigated using nonequilibrium Green's function density functional transport simulations. Cu(001) thin films with thickness d =1 -2 nm are used as a model system, employing a random one-monolayer-high surface roughness and frozen phonons to cause surface and bulk scattering, respectively. The zero-temperature resistivity increases from 9.7 ±1.0 μ Ω cm at d =1.99 nm to 18.7 ±2.6 μ Ω cm at d =0.9 0 nm, contradicting the asymptotic T =0 prediction from the classical Fuchs-Sondheimer model. At T =9 00 K, ρ =5.8 ±0.1 μ Ω cm for bulk Cu and ρ =13.4 ±1.1 and 22.5 ±2.4 μ Ω cm for layers with d =1.99 and 0.90 nm, respectively, indicating an approximately additive phonon contribution which, however, is smaller than for bulk Cu or atomically smooth layers. The overall data indicate that the resistivity contribution from surface scattering is temperature-independent and proportional to 1 /d , suggesting that it can be described using a surface-scattering mean-free path λs for 2D transport which is channel-independent and proportional to d . Data fitting indicates λs=4 ×d for the particular simulated Cu(001) surfaces with a one-monolayer-high surface roughness. The 1 /d dependence deviates considerably from previous 1 /d2 predictions from quantum models, indicating that the small-roughness approximation in these models is not applicable to very thin (<2 nm) layers, where the surface roughness is a considerable fraction of d .

  11. 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

  12. Surface acoustic waves in acoustic superlattice lithium niobate coated with a waveguide layer

    Science.gov (United States)

    Yang, G. Y.; Du, J. K.; Huang, B.; Jin, Y. A.; Xu, M. H.

    2017-04-01

    The effects of the waveguide layer on the band structure of Rayleigh waves are studied in this work based on a one-dimensional acoustic superlattice lithium niobate substrate coated with a waveguide layer. The present phononic structure is formed by the periodic domain-inverted single crystal that is the Z-cut lithium niobate substrate with a waveguide layer on the upper surface. The plane wave expansion method (PWE) is adopted to determine the band gap behavior of the phononic structure and validated by the finite element method (FEM). The FEM is also used to investigate the transmission of Rayleigh waves in the phononic structure with the interdigital transducers by means of the commercial package COMSOL. The results show that, although there is a homogeneous waveguide layer on the surface, the band gap of Rayleigh waves still exist. It is also found that increasing the thickness of the waveguide layer, the band width narrows and the band structure shifts to lower frequency. The present approach can be taken as an efficient tool in designing of phononic structures with waveguide layer.

  13. Surface acoustic waves in acoustic superlattice lithium niobate coated with a waveguide layer

    Directory of Open Access Journals (Sweden)

    G. Y. Yang

    2017-04-01

    Full Text Available The effects of the waveguide layer on the band structure of Rayleigh waves are studied in this work based on a one-dimensional acoustic superlattice lithium niobate substrate coated with a waveguide layer. The present phononic structure is formed by the periodic domain-inverted single crystal that is the Z-cut lithium niobate substrate with a waveguide layer on the upper surface. The plane wave expansion method (PWE is adopted to determine the band gap behavior of the phononic structure and validated by the finite element method (FEM. The FEM is also used to investigate the transmission of Rayleigh waves in the phononic structure with the interdigital transducers by means of the commercial package COMSOL. The results show that, although there is a homogeneous waveguide layer on the surface, the band gap of Rayleigh waves still exist. It is also found that increasing the thickness of the waveguide layer, the band width narrows and the band structure shifts to lower frequency. The present approach can be taken as an efficient tool in designing of phononic structures with waveguide layer.

  14. Effects of plasma cleaning of the Cu seed layer surface on Cu electroplating

    International Nuclear Information System (INIS)

    O, Jun Hwan; Lee, Seong Wook; Kim, Jae Bum; Lee, Chong Mu

    2001-01-01

    Effects of plasma pretreatment to Cu seed/tantalum nitride (TaN)/ borophosphosilicate glass (BPSG) samples on copper (Cu) electroplating were investigated. Copper seed layers were deposited by magnetron sputtering onto tantalum nitride barrier layers before electroplating copper in the forward pulsed mode. The Cu seed layer was cleaned by plasma H 2 and N 2 prior to electroplating a copper film. Cu films electroplated on the copper seed layer with plasma pretreatment showed better electrical and physical properties such as electrical resistivities, surface morphologies, levels of impurities, adhesion and surface roughness than those without plasma pretreatment. It is shown that carbon and metal oxide contaminants at the sputtered Cu seed/TaN surface could be effectively removed by plasma H 2 cleaning. The degree of the (111) prefered orientation of the Cu film with plasma H 2 pretreatment is as high as pulse plated Cu film without plasma pretreatment. Also, plasma H 2 precleaning is more effective in enhancing the Cu electroplating properties onto the Cu seed layer than plasma N 2 precleaning

  15. Analyzing surface features on icy satellites using a new two-layer analogue model

    Science.gov (United States)

    Morales, K. M.; Leonard, E. J.; Pappalardo, R. T.; Yin, A.

    2017-12-01

    The appearance of similar surface morphologies across many icy satellites suggests potentially unified formation mechanisms. Constraining the processes that shape the surfaces of these icy worlds is fundamental to understanding their rheology and thermal evolution—factors that have implications for potential habitability. Analogue models have proven useful for investigating and quantifying surface structure formation on Earth, but have only been sparsely applied to icy bodies. In this study, we employ an innovative two-layer analogue model that simulates a warm, ductile ice layer overlain by brittle surface ice on satellites such as Europa and Enceladus. The top, brittle layer is composed of fine-grained sand while the ductile, lower viscosity layer is made of putty. These materials were chosen because they scale up reasonably to the conditions on Europa and Enceladus. Using this analogue model, we investigate the role of the ductile layer in forming contractional structures (e.g. folds) that would compensate for the over-abundance of extensional features observed on icy satellites. We do this by simulating different compressional scenarios in the analogue model and analyzing whether the resulting features resemble those on icy bodies. If the resulting structures are similar, then the model can be used to quantify the deformation by calculating strain. These values can then be scaled up to Europa or Enceladus and used to quantity the observed surface morphologies and the amount of extensional strain accommodated by certain features. This presentation will focus on the resulting surface morphologies and the calculated strain values from several analogue experiments. The methods and findings from this work can then be expanded and used to study other icy bodies, such as Triton, Miranda, Ariel, and Pluto.

  16. The dynamic deformation of a layered viscoelastic medium under surface excitation

    International Nuclear Information System (INIS)

    Aglyamov, Salavat R; Karpiouk, Andrei B; Emelianov, Stanislav Y; Wang, Shang; Li, Jiasong; Larin, Kirill V; Twa, Michael

    2015-01-01

    In this study the dynamic behavior of a layered viscoelastic medium in response to the harmonic and impulsive acoustic radiation force applied to its surface was investigated both theoretically and experimentally. An analytical solution for a layered viscoelastic compressible medium in frequency and time domains was obtained using the Hankel transform. A special incompressible case was considered to model soft biological tissues. To verify our theoretical model, experiments were performed using tissue-like gel-based phantoms with varying mechanical properties. A 3.5 MHz single-element focused ultrasound transducer was used to apply the radiation force at the surface of the phantoms. A phase-sensitive optical coherence tomography system was used to track the displacements of the phantom surface. Theoretically predicted displacements were compared with experimental measurements. The role of the depth dependence of the elastic properties of a medium in its response to an acoustic pulse at the surface was studied. It was shown that the low-frequency vibrations at the surface are more sensitive to the deep layers than high-frequency ones. Therefore, the proposed model in combination with spectral analysis can be used to evaluate depth-dependent distribution of the mechanical properties based on the measurements of the surface deformation. (paper)

  17. Surface morphology and structure of Ge layer on Si(111) after solid phase epitaxy

    Science.gov (United States)

    Yoshida, Ryoma; Tosaka, Aki; Shigeta, Yukichi

    2018-05-01

    The surface morphology change of a Ge layer on a Si(111) surface formed by solid phase epitaxy has been investigated with a scanning tunneling microscope (STM). The Ge film was deposited at room temperature and annealed at 400 °C or 600 °C. The STM images of the sample surface after annealing at 400 °C show a flat wetting layer (WL) with small three-dimensional islands on the WL. After annealing at 600 °C, the STM images show a surface roughening with large islands. From the relation between the average height of the roughness and the deposited layer thickness, it is confirmed that the diffusion of Ge atoms becomes very active at 600 °C. The Si crystal at the interface is reconstructed and the intermixing occurs over 600 °C. However, the intermixing is fairly restricted in the solid phase epitaxy growth at 400 °C. The surface morphology changes with the crystallization at 400 °C are discussed by the shape of the islands formed on the WL surface. It is shown that the diffusion of the Ge atoms in the amorphous phase is active even at 400 °C.

  18. Topography and surface free energy of DPPC layers deposited on a glass, mica, or PMMA support.

    Science.gov (United States)

    Jurak, Malgorzata; Chibowski, Emil

    2006-08-15

    An investigation of energetic properties of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) layers deposited on glass, mica, and PMMA (poly(methyl methacrylate)) surfaces was carried out by means of contact angles measurements (advancing and receding) for three probe liquids (diiodomethane, water, and formamide). DPPC was deposited on the surfaces from water (on glass and mica) or methanol (on PMMA) solutions. The topography of the tested surfaces was determined with a help of scanning electron microscopy (SEM) and atomic force microscopy (AFM). Using the measured contact angles, the total apparent surface free energy and its components of the studied layers were determined from van Oss et al.'s (Lifshitz-van der Waals and acid-base components, LWAB) and contact angle hysteresis (CAH) approaches. It allowed us to learn about changes in the surface free energy of the layers (hydrophobicity/hydrophilicity) depending on their number and kind of support. It was found that the changes in the energy greatly depended on the surface properties of the substrate as well as the statistical number of monolayers of DPPC. However, principal changes took place for first three monolayers.

  19. Neutralized wettability effect of superhydrophilic Cr-layered surface on pool boiling critical heat flux

    International Nuclear Information System (INIS)

    Son, Hong Hyun; Jeong, Ui Ju; Seo, Gwang Hyeok; Jeun, Gyoo Dong; Kim, Sung Joong

    2016-01-01

    The former method is deemed challenging due to longer development period and license issue. In this regard, FeCrAl, Cr, and SiC have been received positive attention as ATF coating materials because they are highly resistant to high temperature steam reaction causing massive hydrogen generation. In this study, Cr was selected as a target deposition material on the metal substrate because we found that Cr-layered surface becomes superhydrophilic, favorable to delaying the triggering of the critical heat flux (CHF). Thus in order to investigate the effect of Cr-layered superhydrophilic surfaces (under explored coating conditions) on pool boiling heat transfer, pool boiling experiment was conducted in the saturated deionized water under atmospheric pressure. As a physical vapor deposition (PVD) method, the DC magnetron sputtering technique was introduced to develop Cr-layered nanostructure. As a control variable of DC sputtering, substrate temperature was selected. Surface wettability and nanostructure were analyzed as major surface parameters on the CHF. We believe that highly dense micro/nano structure without nucleation cavities and inner pores neutralized the wettability effect on the CHF. Moreover, superhydrophilic surface with deficient cavity density rather hinders active nucleation. This emphasizes the importance of micro/nano structure surface for enhanced boiling heat transfer.

  20. 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.

  1. 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. PMID:25402466

  2. Influence of substrate preparation on the shaping of the topography of the surface of nanoceramic oxide layers

    Science.gov (United States)

    Bara, Marek; Kubica, Marek

    2014-02-01

    The paper discusses the shaping mechanism and changes occurring in the structure and topography of the surface of nanoceramic oxide layers during their formation. The paper presents the influence of substrate preparation on the surface topography of oxide layers. The layers were produced via hard anodizing on the EN AW-5251 aluminum alloy. The layers obtained were subjected to microscope examinations, image and chemical composition analyses, and stereometric examinations. Heredity of substrate properties in the topography of the surface of nanoceramic oxide layers formed as a result of electrochemical oxidation has been shown.

  3. Optical luminescence studies of the ethyl xanthate adsorption layer on the surface of sphalerite minerals.

    Science.gov (United States)

    Todoran, R; Todoran, D; Szakács, Zs

    2016-01-05

    In this work we propose optical luminescence measurements as a method to evaluate the kinetics of adsorption processes. Measurement of the intensity of the integral optical radiation obtained from the mineral-xanthate interface layer, stimulated with a monochromatic pulsating optical signal, as a function of time were made. The luminescence radiation was obtained from the thin interface layer formed at the separation surface between the sphalerite natural mineral and potassium ethyl xanthate solution, for different solution concentrations and pH-es at the constant industry standard temperature. This method enabled us to determine the time to achieve dynamic equilibrium in the formation of the interface layer of approximately 20min, gaining information on the adsorption kinetics in the case of xanthate on mineral surface and leading to the optimization of the industrial froth flotation process. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. The surface layer observed by a high-resolution sodar at DOME C, Antarctica

    Directory of Open Access Journals (Sweden)

    Stefania Argentini

    2014-01-01

    Full Text Available One year field experiment has started on December 2011 at the French - Italian station of Concordia at Dome C, East Antarctic Plateau. The objective of the experiment is the study of the surface layer turbulent processes under stable/very stable stratifications, and the mechanisms leading to the formation of the warming events. A sodar was improved to achieve the vertical/time resolution needed to study these processes. The system, named Surface Layer sodar (SL-sodar, may operate both in high vertical resolution (low range and low vertical resolution (high range modes. In situ turbulence and radiation measurements were also provided in the framework of this experiment. A few preliminary results, concerning the standard summer diurnal cycle, a summer warming event, and unusually high frequency boundary layer atmospheric gravity waves are presented.

  5. Surface plasmons based terahertz modulator consisting of silicon-air-metal-dielectric-metal layers

    Science.gov (United States)

    Wang, Wei; Yang, Dongxiao; Qian, Zhenhai

    2018-05-01

    An optically controlled modulator of the terahertz wave, which is composed of a metal-dielectric-metal structure etched with circular loop arrays on both the metal layers and a photoexcited silicon wafer separated by an air layer, is proposed. Simulation results based on experimentally measured complex permittivities predict that modification of complex permittivity of the silicon wafer through excitation laser leads to a significant tuning of transmission characteristics of the modulator, forming the modulation depths of 59.62% and 96.64% based on localized surface plasmon peak and propagating surface plasmon peak, respectively. The influences of the complex permittivity of the silicon wafer and the thicknesses of both the air layer and the silicon wafer are numerically studied for better understanding the modulation mechanism. This study proposes a feasible methodology to design an optically controlled terahertz modulator with large modulation depth, high speed and suitable insertion loss, which is useful for terahertz applications in the future.

  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. Electron spectroscopy of the interface carbon layer formation on the cleavage surfaces of the layered semiconductor In4Se3 crystals

    International Nuclear Information System (INIS)

    Galiy, P.V.; Musyanovych, A.V.; Nenchuk, T.M.

    2005-01-01

    The results of the quantitative X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) of the interface carbon layer formation on the cleavage surfaces of the layered semiconductor In 4 Se 3 crystals are presented. The carbon coating formation occurs as the result of interaction of the air and residual gases atmosphere in ultra high vacuum (UHV) Auger spectrometer chamber with atomic clean interlayer cleavage surfaces of the crystals. The kinetics and peculiarities of interfacial carbon layer formation on the cleavage surfaces of the crystals, elemental and phase composition of the interface have been studied by quantitative XPS, AES and mass-spectroscopy

  8. Corrosion product layers on magnesium alloys AZ31 and AZ61: Surface chemistry and protective ability

    Science.gov (United States)

    Feliu, S.; Llorente, I.

    2015-08-01

    This paper studies the chemical composition of the corrosion product layers formed on magnesium alloys AZ31 and AZ61 following immersion in 0.6 M NaCl, with a view to better understanding their protective action. Relative differences in the chemical nature of the layers were quantified by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDX) and low-angle X-ray diffraction (XRD). Corrosion behavior was investigated by Electrochemical Impedance Spectroscopy (EIS) and hydrogen evolution measurement. An inhibitive effect from the corrosion product layers was observed from EIS, principally in the case of AZ31, as confirmed by hydrogen evolution tests. A link was found between carbonate enrichment observed by XPS in the surface of the corrosion product layer, concomitant with the increase in the protective properties observed by EIS.

  9. Steady ablation on the surface of a two-layer composite

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Wen-Shan [Chung Shan Institute of Science and Technology, P.O. Box 90008-15-3, Lung-Tan, Tao-Yuan, 32526 Taiwan (China)

    2005-12-01

    Discovered is a quasi-steady ablation phenomenon on the surface of a two-layer composite which is formed by a layer of ablative material and another layer of non-ablative substrate. Theoretical exact solutions of quasi-steady ablation rate, the associated temperature distribution and end-of-ablation time of this two-layer composite are derived. A criterion for the occurrence of quasi-steady ablation is presented also. A one-dimensional transient numerical model is developed to perform a number of numerical experiments and hence to verify the correctness of the above theoretical solutions for the current quasi-steady ablation phenomenon. Based on the current results, a new method of measuring the ablation (or sublimation) heat is also proposed. (author)

  10. Two-phase gas bubble-liquid boundary layer flow along vertical and inclined surfaces

    International Nuclear Information System (INIS)

    Cheung, F.B.; Epstein, M.

    1985-01-01

    The behavior of a two-phase gas bubble-liquid boundary layer along vertical and inclined porous surfaces with uniform gas injection is investigated experimentally and analytically. Using argon gas and water as the working fluids, a photographical study of the two-phase boundary layer flow has been performed for various angles of inclination ranging from 45 0 to 135 0 and gas injection rates ranging from 0.01 to 0.1 m/s. An integral method has been employed to solve the system of equations governing the two-phase motion. The effects of the gas injection rate and the angle of inclination on the growth of the boundary layer have been determined. The predicted boundary layer thickness is found to be in good agreement with the experimental results. The calculated axial liquid velocity and the void fraction in the two-phase region are also presented along with the observed flow behavior

  11. 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.

  12. 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

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

    NARCIS (Netherlands)

    Meuwese, M.C.; Broekhuizen, L.N.; Kuikhoven, M.; Heeneman, S.; Lutgens, E.; Gijbels, M.J.J.; Nieuwdorp, M.; Peutz, C.J.; Stroes, E.S.G.; Vink, H.; van den Berg, B.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

  14. Structural and electronic properties of single molecules and organic layers on surfaces

    NARCIS (Netherlands)

    Sotthewes, Kai

    2016-01-01

    Single molecules and organic layers on well-defined solid surfaces have attracted tremendous attention owing to their interesting physical and chemical properties. The ultimate utility of single molecules or self-assembled monolayers (SAMs) for potential applications is critically dependent on the

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

    Indian Academy of Sciences (India)

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

    Abstract. The frequency equation is derived for surface waves in a liquid- saturated 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 spe-.

  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. Thermal stresses calculations in near-surface layers of sphere bodies, falling to the Sun

    International Nuclear Information System (INIS)

    Demchenko, B.I.; Shestakova, L.I.

    2005-01-01

    Profiles of temperature and temperature stresses in surface layers of silicate and icy spheric bodies, falling to the Sun along parabolic orbits were obtained on the base of the analytical solution of the linear heat diffusion equation. Results may be useful for thermal evolution analysis of meteor and comet bodies in the Sun system. (author)

  18. 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...

  19. Study on mechanics of driving drum with superelastic convexity surface covering-layer structure

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, L.J.; Sui, X.H.; Miao, D.J. [Shandong University of Science & Technology, Qingdao (China)

    2008-09-15

    Belt conveyor is one of the main transport equipment in coal mine and the driving drum is its key part. With the method of bionic design, the mushroom morphological structure is applied to the design of covering-layer structure of driving drum surface of belt conveyor. Superelastic rubber with large deformation is adopted as the covering-layer material. Nonlinear constitutive model of rubber, which is of superelasticity and large deformation, is established. The stress states and deformation principles of driving drums including both bionic covering-layer and common covering-layer are obtained by static intensity analysis with Finite Element Analysis (FEA) software ANSYS. The values of the stress and strain on the driving drum surface are gotten and the dangerous area is determined. FEA results show that the superelastic convexity surface structure can enlarge the contact area between the driving drum and viscoelastic belt. The results also show that in comparison with common driving drum, the bionic surface driving drum can not only increase the friction coefficient between drum and belt but also prolong its service life.

  20. 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

  1. 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.

  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. Structure and Construction Assessment of the Surface Layer of Hardfaced Coating after Friction

    Directory of Open Access Journals (Sweden)

    Krzysztof Dziedzic

    2017-09-01

    Full Text Available The paper presents an analysis of the surface layer of Fe-Mn-C-B-Si-Ni-Cr alloy coating after friction with C45 steel. The coatings were obtained by arc welding (GMA. Flux-cored wires were used as a welding material. The flux-cored wires had a diameter of 2,4 mm. The tribological assessment was performed with the Amsler tribotester under dry friction conditions at unit pressures 10 MPa. The use of XPS spectroscopy allowed deep profile analysis of the surface layer. Based on the obtained results developed model of the surface layer for friction couple, hardfaced coating obtained from Fe-Mn-C-B-Si-Ni-Cr alloy – C45 steel. It was observed that the operational surface layer (OSL of hardfaced coatings contained oxides (B2O3, SiO2, NiO, Cr2O3, FeO, Fe3O4, Fe2O3, carbides (Fe3C, Cr7C3 and borides (FeB, Fe2B.

  4. 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

  5. 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...

  6. 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

  7. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Keturakis, Christopher J. [Operando Molecular Spectroscopy and Catalysis Research Laboratory, Department of Chemical Engineering, Lehigh University, Bethlehem, PA 18015 (United States); Notis, Ben [Brandeis University, Waltham, MA 02453 (United States); Blenheim, Alex [Department of Mechanical Engineering, Pennsylvania State University, College Park, PA 16802 (United States); Miller, Alfred C.; Pafchek, Rob [Zettlemoyer Center for Surface Studies, Lehigh University, Bethlehem, PA 18015 (United States); Notis, Michael R., E-mail: mrn1@lehigh.edu [Department of Materials Science and Engineering, Lehigh University, Bethlehem, PA 18015 (United States); Wachs, Israel E., E-mail: iew0@lehigh.edu [Operando Molecular Spectroscopy and Catalysis Research Laboratory, Department of Chemical Engineering, Lehigh University, Bethlehem, PA 18015 (United States)

    2016-07-15

    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{sub 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{sub 2}O, Na, Al, Pb, and adsorbed hydrocarbons, while the more recent coins, from 98 to 244 CE, contained Cu{sub 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{sub 2}O layer. Depth profiling revealed the presence of K, Na, Cl, and

  9. 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

  10. 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.

  11. 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

  12. LDV measurement of boundary layer on rotating blade surface in wind tunnel

    Science.gov (United States)

    Maeda, Takao; Kamada, Yasunari; Murata, Junsuke; Suzuki, Daiki; Kaga, Norimitsu; Kagisaki, Yosuke

    2014-12-01

    Wind turbines generate electricity due to extracting energy from the wind. The rotor aerodynamics strongly depends on the flow around blade. The surface flow on the rotating blade affects the sectional performance. The wind turbine surface flow has span-wise component due to span-wise change of airfoil section, chord length, twisted angle of blade and centrifugal force on the flow. These span-wise flow changes the boundary layer on the rotating blade and the sectional performance. Hence, the thorough understanding of blade surface flow is important to improve the rotor performance. For the purpose of clarification of the flow behaviour around the rotor blade, the velocity in the boundary layer on rotating blade surface of an experimental HAWT was measured in a wind tunnel. The velocity measurement on the blade surface was carried out by a laser Doppler velocimeter (LDV). As the results of the measurement, characteristics of surface flow are clarified. In optimum tip speed operation, the surface flow on leading edge and r/R=0.3 have large span-wise velocity which reaches 20% of sectional inflow velocity. The surface flow inboard have three dimensional flow patterns. On the other hand, the flow outboard is almost two dimensional in cross sectional plane.

  13. 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

  14. 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)

  15. SURFACE LAYER ACCRETION IN TRANSITIONAL AND CONVENTIONAL DISKS: FROM POLYCYCLIC AROMATIC HYDROCARBONS TO PLANETS

    International Nuclear Information System (INIS)

    Perez-Becker, Daniel; Chiang, Eugene

    2011-01-01

    'Transitional' T Tauri disks have optically thin holes with radii ∼>10 AU, yet accrete up to the median T Tauri rate. Multiple planets inside the hole can torque the gas to high radial speeds over large distances, reducing the local surface density while maintaining accretion. Thus multi-planet systems, together with reductions in disk opacity due to grain growth, can explain how holes can be simultaneously transparent and accreting. There remains the problem of how outer disk gas diffuses into the hole. Here it has been proposed that the magnetorotational instability (MRI) erodes disk surface layers ionized by stellar X-rays. In contrast to previous work, we find that the extent to which surface layers are MRI-active is limited not by ohmic dissipation but by ambipolar diffusion, the latter measured by Am: the number of times a neutral hydrogen molecule collides with ions in a dynamical time. Simulations by Hawley and Stone showed that Am ∼ 100 is necessary for ions to drive MRI turbulence in neutral gas. We calculate that in X-ray-irradiated surface layers, Am typically varies from ∼10 -3 to 1, depending on the abundance of charge-adsorbing polycyclic aromatic hydrocarbons, whose properties we infer from Spitzer observations. We conclude that ionization of H 2 by X-rays and cosmic rays can sustain, at most, only weak MRI turbulence in surface layers 1-10 g cm -2 thick, and that accretion rates in such layers are too small compared to observed accretion rates for the majority of disks.

  16. Optical and electrical properties of porous silicon layer formed on the textured surface by electrochemical etching

    Science.gov (United States)

    Weiying, Ou; Lei, Zhao; Hongwei, Diao; Jun, Zhang; Wenjing, Wang

    2011-05-01

    Porous silicon (PS) layers were formed on textured crystalline silicon by electrochemical etching in HF-based electrolyte. Optical and electrical properties of the TMAH textured surfaces with PS formation are studied. Moreover, the influences of the initial structures and the anodizing time on the optical and electrical properties of the surfaces after PS formation are investigated. The results show that the TMAH textured surfaces with PS formation present a dramatic decrease in reflectance. The longer the anodizing time is, the lower the reflectance. Moreover, an initial surface with bigger pyramids achieved lower reflectance in a short wavelength range. A minimum reflectance of 3.86% at 460 nm is achieved for a short anodizing time of 2 min. Furthermore, the reflectance spectrum of the sample, which was etched in 3 vol.% TMAH for 25 min and then anodized for 20 min, is extremely flat and lies between 3.67% and 6.15% in the wavelength range from 400 to 1040 nm. In addition, for a short anodizing time, a slight increase in the effective carrier lifetime is observed. Our results indicate that PS layers formed on a TMAH textured surface for a short anodization treatment can be used as both broadband antireflection coatings and passivation layers for the application in solar cells.

  17. Optical and electrical properties of porous silicon layer formed on the textured surface by electrochemical etching

    Energy Technology Data Exchange (ETDEWEB)

    Ou Weiying; Zhao Lei; Diao Hongwei; Zhang Jun; Wang Wenjing, E-mail: wjwangwj@126.com [Key Laboratory of Solar Thermal Energy and Photovoltaic System, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China)

    2011-05-15

    Porous silicon (PS) layers were formed on textured crystalline silicon by electrochemical etching in HF-based electrolyte. Optical and electrical properties of the TMAH textured surfaces with PS formation are studied. Moreover, the influences of the initial structures and the anodizing time on the optical and electrical properties of the surfaces after PS formation are investigated. The results show that the TMAH textured surfaces with PS formation present a dramatic decrease in reflectance. The longer the anodizing time is, the lower the reflectance. Moreover, an initial surface with bigger pyramids achieved lower reflectance in a short wavelength range. A minimum reflectance of 3.86% at 460 nm is achieved for a short anodizing time of 2 min. Furthermore, the reflectance spectrum of the sample, which was etched in 3 vol.% TMAH for 25 min and then anodized for 20 min, is extremely flat and lies between 3.67% and 6.15% in the wavelength range from 400 to 1040 nm. In addition, for a short anodizing time, a slight increase in the effective carrier lifetime is observed. Our results indicate that PS layers formed on a TMAH textured surface for a short anodization treatment can be used as both broadband antireflection coatings and passivation layers for the application in solar cells. (semiconductor technology)

  18. Production of metal fullerene surface layer from various media in the process of steel carbonization

    Directory of Open Access Journals (Sweden)

    KUZEEV Iskander Rustemovich

    2018-04-01

    Full Text Available Studies devoted to production of metal fullerene layer in steels when introducing carbon from organic and inorganic media were performed. Barium carbonate was used as an inorganic medium and petroleum pitch was used as an organic medium. In order to generate the required amount of fullerenes in the process of steel samples carbonization, optimal temperature mode was found. The higher temperature, absorption and cohesive effects become less important and polymeric carbon structures destruction processes become more important. On the bottom the temperature is limited by petroleum pitch softening temperature and its transition to low-viscous state in order to enhance molecular mobility and improve the possibility of their diffusion to metal surface. Identification of fullerenes in the surface modified layer was carried out following the methods of IR-Fourier spectrometry and high-performance liquid chromatography. It was found out that nanocarbon structures, formed during carbonization in barium carbonate and petroleum pitch mediums, possess different morphology. In the process of metal carbonization from carbonates medium, the main role in fullerenes synthesis is belonged to catalytic effect of surface with generation of endohedral derivatives in the surface layer; but in the process of carbonization from pitch medium fullerenes are formed during crystallization of the latter and crystallization centers are of fullerene type. Based on theoretical data and dataof spectral and chromatographic analysis, optimal conditions of metal fullerene layer formation in barium carbonate and petroleum pitch mediums were determined. Low cohesion of layer, modified in barium carbonate medium, with metal basis was discovered. That was caused by limited carbon diffusion in the volume of α-Fe. According to the detected mechanism of fullerenes formation on steel surface in gaseous medium, fullerenes are formed on catalytic centers – ferrum atoms, forming thin metal

  19. 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.

  20. 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

  1. 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.

  2. The Response of the Ocean Thermal Skin Layer to Air-Sea Surface Heat Fluxes

    Science.gov (United States)

    Wong, Elizabeth Wing-See

    There is much evidence that the ocean is heating as a result of an increase in concentrations of greenhouse gases (GHGs) in the atmosphere from human activities. GHGs absorb infrared radiation and re-emit infrared radiation back to the ocean's surface which is subsequently absorbed. However, the incoming infrared radiation is absorbed within the top micrometers of the ocean's surface which is where the thermal skin layer exists. Thus the incident infrared radiation does not directly heat the upper few meters of the ocean. We are therefore motivated to investigate the physical mechanism between the absorption of infrared radiation and its effect on heat transfer at the air-sea boundary. The hypothesis is that since heat lost through the air-sea interface is controlled by the thermal skin layer, which is directly influenced by the absorption and emission of infrared radiation, the heat flow through the thermal skin layer adjusts to maintain the surface heat loss, assuming the surface heat loss does not vary, and thus modulates the upper ocean heat content. This hypothesis is investigated through utilizing clouds to represent an increase in incoming longwave radiation and analyzing retrieved thermal skin layer vertical temperature profiles from a shipboard infrared spectrometer from two research cruises. The data are limited to night-time, no precipitation and low winds of less than 2 m/s to remove effects of solar radiation, wind-driven shear and possibilities of thermal skin layer disruption. The results show independence of the turbulent fluxes and emitted radiation on the incident radiative fluxes which rules out the immediate release of heat from the absorption of the cloud infrared irradiance back into the atmosphere through processes such as evaporation and increase infrared emission. Furthermore, independence was confirmed between the incoming and outgoing radiative flux which implies the heat sink for upward flowing heat at the air-sea interface is more

  3. 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.

  4. Surface pressure drag for hydrostatic two-layer flow over axisymmetric mountains

    Energy Technology Data Exchange (ETDEWEB)

    Leutbecher, M.

    2000-07-01

    The effect of partial reflections on surface pressure drag is investigated for hydrostatic gravity waves in two-layer flow with piecewise constant buoyancy frequency. The variation of normalized surface pressure drag with interface height is analyzed for axisymmetric mountains. The results are compared with the familiar solution for infinitely long ridges. The drag for the two-layer flow is normalized with the drag of one-layer flow, which has the buoyancy frequency of the lower layer. An analytical expression for the normalized drag of axisymmetric mountains is derived from linear theory of steady flow. Additionally, two-layer flow over finite-height axisymmetric mountains is simulated numerically for flow with higher stability in the upper layer. The temporal evolution of the surface pressure drag is examined in a series of experiments with different interface and mountain heights. The focus is on the linear regime and the nonlinear regime of nonbreaking gravity waves. The dispersion of gravity waves in flow over isolated mountains prevents that the entire wave spectrum is in resonance at the same interface height, which is the case in hydrostatic flow over infinitely long ridges. In consequence, the oscillation of the normalized drag with interface height is smaller for axisymmetric mountains than for infinitely long ridges. However, even for a reflection coefficient as low as 1/3 the drag of an axisymmetric mountain can be amplified by 50% and reduced by 40%. The nonlinear drag becomes steady in the numerical experiments in which no wave breaking occurs. The steady state nonlinear drag agrees quite well with the prediction of linear theory if the linear drag is computed for a slightly lowered interface. (orig.)

  5. High Reynolds number rough wall turbulent boundary layer experiments using Braille surfaces

    Science.gov (United States)

    Harris, Michael; Monty, Jason; Nova, Todd; Allen, James; Chong, Min

    2007-11-01

    This paper details smooth, transitional and fully rough turbulent boundary layer experiments in the New Mexico State high Reynolds number rough wall wind tunnel. The initial surface tested was generated with a Braille printer and consisted of an uniform array of Braille points. The average point height being 0.5mm, the spacing between the points in the span was 0.5mm and the surface consisted of span wise rows separated by 4mm. The wavelength to peak ratio was 8:1. The boundary layer thickness at the measurement location was 190mm giving a large separation of roughness height to layer thickness. The maximum friction velocity was uτ=1.5m/s at Rex=3.8 x10^7. Results for the skin friction co-efficient show that this surface follows a Nikuradse type inflectional curve and that Townsends outer layer similarity hypothesis is valid for rough wall flows with a large separation of scales. Mean flow and turbulence statistics will be presented.

  6. Selenopentathionic and Telluropentathionic Acids as Precursors for Formation of Semiconducting Layers on the Surface of Polyamide

    Directory of Open Access Journals (Sweden)

    Skirma Zalenkiene

    2007-01-01

    Full Text Available The layers of copper chalcogenides, which were formed on the surface of semihydrophilic polymer—polyamide 6 (PA using monoselenopentathionic H2SeS4O6 and monotelluropentathionic H2TeS4O6 acids as precursors of chalcogens, were characterized. Fourier transform infrared (FT-IR and UV spectroscopy were used to monitor the effect of chalcogens on the changes in structure of PA corresponding to the concentration of the precursor's solution and an exposure time. The IR spectra of modified PA were completely different from that of the initial PA. Further interaction of chalcogenized PA with copper (II/I salt solution leads to the formation of CuxS, CuxSe, CuxTe, and mixed –CuxS–CuySe and CuxS–CuyTe layers which have different electric transport properties. The surface properties of PA after treatment are studied using AFM and XRD. The electrical resistances of layers with various composition formed over a wide concentration range 0.01–0.5 mol⋅dm−3 of precursor's solution were measured. Variation in the conductivity of layers of Cu–Se–S and Cu–Te–S on the surface of PA shows an evident increase with the increasing of the mass fraction of selenium or tellurium.

  7. Characterization of transfer layers on steel surfaces sliding against diamondlike carbon in dry nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, A.; Bindal, C.; Pagan, J. [Argonne National Lab., IL (United States); Wilbur, P. [Colorado State Univ., Fort Collins, CO (United States). Dept. of Mechanical Engineering

    1995-03-01

    Transfer layers on sliding steel surfaces play important roles in tribological performance of diamondlike carbon films. This study investigated the nature of transfer layers formed on M50 balls during sliding against diamondlike carbon (DLC) films (1.5 {mu}m thick) prepared by ion-beam deposition. Long-duration sliding tests were performed with steel balls sliding against the DLC coatings in dry nitrogen at room temperature and zero humidity. Test results indicated that the friction coefficients of test pairs were initially 0.12 but decreased steadily with sliding distance to 0.02-0.03 and remained constant throughout the tests, which lasted for more than 250,000 sliding cycles (30 km). This low-friction regime appeared to coincide with the formation of a carbon-rich transfer layer on the sliding surfaces of M50 balls. Micro-laser-Raman spectroscopy and electron microscopy were used to elucidate the structure and chemistry of these transfer layers and to reveal their possible role in the wear and friction behavior of DLC-coated surfaces.

  8. 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

  9. 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.

  10. 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.

  11. The role of surface charging during the coadsorption of mercaptohexanol to DNA layers on gold: direct observation of desorption and layer reorientation.

    Science.gov (United States)

    Arinaga, K; Rant, U; Tornow, M; Fujita, S; Abstreiter, G; Yokoyama, N

    2006-06-20

    We study the coadsorption of mercaptohexanol onto preimmobilized oligonucleotide layers on gold. Monitoring the position of the DNA relative to the surface by optical means directly shows the mercaptohexanol-induced desorption of DNA and the reorientation of surface-tethered strands in situ and in real time. By simultaneously recording the electrochemical electrode potential, we are able to demonstrate that changes in the layer conformation are predominantly of electrostatic origin and can be reversed by applying external bias to the substrate.

  12. Multiple layered metallic nanostructures for strong surface-enhanced Raman spectroscopy enhancement

    International Nuclear Information System (INIS)

    Xia, Ming; Xie, Ya-Hong; Qiao Kuan; Cheng Zhiyuan

    2016-01-01

    We report a systematic study on a practical way of patterning metallic nanostructures to achieve high surface-enhanced Raman spectroscopy (SERS) enhancement factors (EFs) and high hot-spot density. By simply superimposing a 1-layer Au nanotriangle array on another to form a multilayer nanotriangle array, the SERS signal can be enhanced by 2 orders of magnitude compared with a 1-layer nanotriangle array. The drastic increases in the SERS EF and the hot spot density of the multilayer Au nanotriangle array are due to the increase in the number of gaps formed between Au nanotriangles and the decrease of the gap width. (author)

  13. Tuning of turbulent boundary layer anisotropy for improved surface pressure and trailing-edge noise modeling

    DEFF Research Database (Denmark)

    Bertagnolio, Franck; Fischer, Andreas; Zhu, Wei Jun

    2014-01-01

    The modeling of the surface pressure spectrum beneath a turbulent boundary layer is investigated, focusing on the case of airfoil flows and associated trailing edge noise prediction using the so-called TNO model. This type of flow is characterized by the presence of an adverse pressure gradient...... along the airfoil chord. It is shown that discrepancies between measurements and results from the TNO model increase as the pressure gradient increases. The original model is modified by introducing anisotropy in the definition of the turbulent vertical velocity spectrum across the boundary layer...

  14. Pulsations of white dwarf stars with thick hydrogen or helium surface layers

    Energy Technology Data Exchange (ETDEWEB)

    Cox, A.N.; Starrfield, S.G.; Kidman, R.B.; Pesnell, W.D.

    1986-07-01

    In order to see if there could be agreement between results of stellar evolution theory and those of nonradial pulsation theory, calculations of white dwarf models have been made for hydrogen surface masses of 10/sup -4/ solar masses. Earlier results indicated that surface masses greater than 10/sup -8/ solar masses would not allow nonradial pulsations, even though all the driving and damping is in surface layers only 10/sup -12/ of the mass thick. It is shown that the surface mass of hydrogen in the pulsating white dwarfs (ZZ Ceti variables) can be any value as long as it is thick enough to contain the surface convection zone. 10 refs., 6 figs.

  15. Effect of the surface charge discretization on electric double layers: a Monte Carlo simulation study.

    Science.gov (United States)

    Madurga, Sergio; Martín-Molina, Alberto; Vilaseca, Eudald; Mas, Francesc; Quesada-Pérez, Manuel

    2007-06-21

    The structure of the electric double layer in contact with discrete and continuously charged planar surfaces is studied within the framework of the primitive model through Monte Carlo simulations. Three different discretization models are considered together with the case of uniform distribution. The effect of discreteness is analyzed in terms of charge density profiles. For point surface groups, a complete equivalence with the situation of uniformly distributed charge is found if profiles are exclusively analyzed as a function of the distance to the charged surface. However, some differences are observed moving parallel to the surface. Significant discrepancies with approaches that do not account for discreteness are reported if charge sites of finite size placed on the surface are considered.

  16. Fast biosensor with reagent layer

    NARCIS (Netherlands)

    2008-01-01

    A detection system and a sensor chip for detecting target mols., and thus corresponding analytes in a sample is described. Typically the detection system includes a sensor chip. The sensor chip (1) comprises on its detection surface a dissolvable reagent layer. When the dissolvable reagent layer is

  17. Study of the process of positron annihilation in GaAs disturbed surface layers

    International Nuclear Information System (INIS)

    Vorob'ev, A.A.; Aref'ev, K.P.; Vorob'ev, S.A.; Karetnikov, A.S.; Prokop'ev, E.P.; Kuznetsov, Yu.N.; Khashimov, F.R.; Markova, T.I.

    1977-01-01

    The effect was investigated of single-crystal semiconductor surface treatment types on positron annihilation characteristics. CaAs single-crystal specimens were investigated with the following surface treatment types: (a) polishing with Al 2 O 3 abrasive powder water suspension; (b) mechanical polishing with diamond paste; (c) mechanical chemical polishing with Al 2 O 3 or ZrO 2 suspensions; (d) chemical polishing with the 1HF:3HNO 3 :2H 2 O mixture. The investigation of annihilation was performed by the method of distinguishing the narrow component Isub(N) from correlation curves in 14.5 kOc statical magnetic field and by that of measuring the relative value of friquantuum annihilation Psub(3γ). The maximum Isub(N) and Psub(3γ) values are shown to occur in GaAs specimens with the (d) type of treatment. The experimental data provided a conclusion about the presence of a maximum thickness oxide layer of complex composition on the surface of the specimens compared with oxide layer thicknesses on the surface of specimens with (a), (b), and (c) treatmens. It is concluded that the positron annihilation method may be successfully used for the study of semiconductor material oxide layers

  18. 2D layered insulator hexagonal boron nitride enabled surface passivation in dye sensitized solar cells.

    Science.gov (United States)

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

    2013-11-21

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

  19. Observational study of atmospheric surface layer and coastal weather in northern Qatar

    Science.gov (United States)

    Samanta, Dhrubajyoti; Sadr, Reza

    2016-04-01

    Atmospheric surface layer is the interaction medium between atmosphere and Earth's surface. Better understanding of its turbulence nature is essential in characterizing the local weather, climate variability and modeling of turbulent exchange processes. The importance of Middle East region, with its unique geographical, economical and weather condition is well recognized. However, high quality micrometeorological observational studies are rare in this region. Here we show experimental results from micrometeorological observations from an experimental site in the coastal region of Qatar during August-December 2015. Measurements of winds are obtained from three sonic anemometers installed on a 9 m tower placed at Al Ghariyah beach in northern Qatar (26.08 °N, 51.36 °E). Different surface layer characteristics is analyzed and compared with earlier studies in equivalent weather conditions. Monthly statistics of wind speed, wind direction, temperature, humidity and heat index are made from concurrent observations from sonic anemometer and weather station to explore variations with surface layer characteristics. The results also highlights potential impact of sea breeze circulation on local weather and atmospheric turbulence. The observed daily maximum temperature and heat index during morning period may be related to sea breeze circulations. Along with the operational micrometeorological observation system, a camera system and ultrasonic wave measurement system are installed recently in the site to study coastline development and nearshore wave dynamics. Overall, the complete observational set up is going to provide new insights about nearshore wind dynamics and wind-wave interaction in Qatar.

  20. Effect of Mo Ion Implantation on Stability of Nanocrystalline Copper Surface Layers

    Directory of Open Access Journals (Sweden)

    XI Yang

    2016-08-01

    Full Text Available The surface of pure copper was modified using the surface mechanical attrition treatment (SMAT method, and molybdenum ions were implanted in the nanosurface using a metal vapor vacuum arc (MEVVA. The results of the SMAT were observed by optical microscopy (OM, X-ray diffraction (XRD and scanning electron microscopy (SEM. An obvious nanocrystalline layer and a deformation region exist on the surface. The size of the nanocrystalline layer was characterized using atomic force microscopy (AFM. The results indicate remarkable suppression on grain size, the nanocrystalline layer grows to 163nm after annealing and reduces to only 72nm due to the Mo ion implantation. In addition, the hardness of the topmost surface of the material is 3.5 times that of the SMATed copper, which is about 7 times of the value of the matrix. The above improvements most likely result from the dispersion of the Mo ions and the reactions of the crystal defects due to the SMAT and ion implantation.

  1. 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

  2. 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

  3. 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.

  4. Evaluation of Bending Strength of Carburized Gears Based on Inferential Identification of Principal Surface Layer Defects

    Science.gov (United States)

    Masuyama, Tomoya; Inoue, Katsumi; Yamanaka, Masashi; Kitamura, Kenichi; Saito, Tomoyuki

    High load capacity of carburized gears originates mainly from the hardened layer and induced residual stress. On the other hand, surface decarburization, which causes a nonmartensitic layer, and inclusions such as oxides and segregation act as latent defects which considerably reduce fatigue strength. In this connection, the authors have proposed a formula of strength evaluation by separately quantifying defect influence. However, the principal defect which limits strength of gears with several different defects remains unclarified. This study presents a method of inferential identification of principal defects based on test results of carburized gears made of SCM420 clean steel, gears with both an artificial notch and nonmartensitic layer at the tooth fillet, and so forth. It clarifies practical uses of presented methods, and strength of carburized gears can be evaluated by focusing on principal defect size.

  5. 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.

  6. 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

    -Obukhov similarity. Above the surface layer the second length scale (L-MBL ) becomes independent of height but not of stability, and at the top of the boundary layer the third length scale is assumed to be negligible. A simple model for the combined length scale that controls the wind profile and its stability...... dependence is formulated by inverse summation. Based on these assumptions the wind profile for the entire boundary layer is derived. A parameterization of L-MBL is formulated using the geostrophic drag law, which relates friction velocity and geostrophic wind. The empirical parameterization of the resistance...... law functions A and B in the geostrophic drag law is uncertain, making it impractical. Therefore an expression for the length scale, L-MBL , for applied use is suggested, based on measurements from the two sites....

  7. Two-phase gas bubble-liquid boundary layer flow along vertical and inclined surfaces

    International Nuclear Information System (INIS)

    Cheung, F.B.; Epstein, M.

    1985-01-01

    The behavior of a two-phase gas bubble liquid boundary layer along vertical and inclined porous surfaces with uniform gas injection is investigated experimentally and analytically. Using argon gas and water as the working fluids, a photographical study of the two-phase boundary layer flow has been performed for various angles of inclination ranging from 45 0 to 135 0 and gas injection rates ranging from 0.01 to 0.1 m/s. An integral method has been employed to solve the system of equations governing the two-phase motion. The effects of the gas injection rate and the angle of inclination on the growth of the boundary layer have been determined

  8. Trace and surface analysis of ceramic layers of solid oxide fuel cells by mass spectrometry.

    Science.gov (United States)

    Becker, J S; Breuer, U; Westheide, J; Saprykin, A I; Holzbrecher, H; Nickel, H; Dietze, H J

    1996-06-01

    For the trace analysis of impurities in thick ceramic layers of a solid oxide fuel cell (SOFC) sensitive solid-state mass spectrometric methods, such as laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and radiofrequency glow discharge mass spectrometry (rf-GDMS) have been developed and used. In order to quantify the analytical results of LA-ICP-MS, the relative sensitivity coefficients of elements in a La(0.6)Sr(0.35)MnO(3) matrix have been determined using synthetic standards. Secondary ion mass spectrometry (SIMS) - as a surface analytical method - has been used to characterize the element distribution and diffusion profiles of matrix elements on the interface of a perovskite/Y-stabilized ZrO(2) layer. The application of different mass spectrometric methods for process control in the preparation of ceramic layers for the SOFC is described.

  9. Atomic-layer-resolved analysis of surface magnetism by diffraction spectroscopy

    International Nuclear Information System (INIS)

    Matsui, Fumihiko; Matsushita, Tomohiro; Daimon, Hiroshi

    2010-01-01

    X-ray absorption near edge structure (XANES) and X-ray magnetic circular dichroism (XMCD) measurements by Auger-electron-yield detection are powerful analysis tools for the electronic and magnetic structures of surfaces, but all the information from atoms within the electron mean-free-path range is summed into the obtained spectrum. In order to investigate the electronic and magnetic structures of each atomic layer at subsurface, we have proposed a new method, diffraction spectroscopy, which is the combination of X-ray absorption spectroscopy and Auger electron diffraction (AED). From a series of measured thickness dependent AED patterns, we deduced a set of atomic-layer-specific AED patterns arithmetically. Based on these AED patterns, we succeeded in disentangling obtained XANES and XMCD spectra into those from different atomic layers.

  10. 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

  11. Preparation of Two-Layer Anion-Exchange Poly(ethersulfone Based Membrane: Effect of Surface Modification

    Directory of Open Access Journals (Sweden)

    Lucie Zarybnicka

    2016-01-01

    Full Text Available The present work deals with the surface modification of a commercial microfiltration poly(ethersulfone membrane by graft polymerization technique. Poly(styrene-co-divinylbenzene-co-4-vinylbenzylchloride surface layer was covalently attached onto the poly(ethersulfone support layer to improve the membrane electrochemical properties. Followed by amination, a two-layer anion-exchange membrane was prepared. The effect of surface layer treatment using the extraction in various solvents on membrane morphological and electrochemical characteristics was studied. The membranes were tested from the point of view of water content, ion-exchange capacity, specific resistance, permselectivity, FT-IR spectroscopy, and SEM analysis. It was found that the two-layer anion-exchange membranes after the extraction using tetrahydrofuran or toluene exhibited smooth and porous surface layer, which resulted in improved ion-exchange capacity, electrical resistance, and permselectivity of the membranes.

  12. Observation of low-frequency acoustic surface waves in the nocturnal boundary layer.

    Science.gov (United States)

    Talmadge, Carrick L; Waxler, Roger; Di, Xiao; Gilbert, Kenneth E; Kulichkov, Sergey

    2008-10-01

    A natural terrain surface, because of its porosity, can support an acoustic surface wave that is a mechanical analog of the familiar vertically polarized surface wave in AM radio transmission. At frequencies of several hundred hertz, the acoustic surface wave is attenuated over distances of a few hundred meters. At lower frequencies (e.g., below approximately 200 Hz) the attenuation is much less, allowing surface waves to propagate thousands of meters. At night, a low-frequency surface wave is generally present at long ranges even when downward refraction is weak. Thus, surface waves represent a ubiquitous nighttime transmission mode that exists even when other transmission modes are weak or absent. Data from recent nighttime field experiments and theoretical calculations are presented, demonstrating the persistence of the surface wave under different meteorological conditions. The low-frequency surface wave described here is the "quasiharmonical" tail observed previously in nighttime measurements but not identified by S. Kulichkov and his colleagues (Chunchuzov, I. P. et al. 1990. "On acoustical impulse propagation in a moving inhomogeneous atmospheric layer," J. Acoust. Soc. Am. 88, 455-461).

  13. Determination of Surface Potential and Electrical Double-Layer Structure at the Aqueous Electrolyte-Nanoparticle Interface

    Directory of Open Access Journals (Sweden)

    Matthew A. Brown

    2016-01-01

    Full Text Available The structure of the electrical double layer has been debated for well over a century, since it mediates colloidal interactions, regulates surface structure, controls reactivity, sets capacitance, and represents the central element of electrochemical supercapacitors. The surface potential of such surfaces generally exceeds the electrokinetic potential, often substantially. Traditionally, a Stern layer of nonspecifically adsorbed ions has been invoked to rationalize the difference between these two potentials; however, the inability to directly measure the surface potential of dispersed systems has rendered quantitative measurements of the Stern layer potential, and other quantities associated with the outer Helmholtz plane, impossible. Here, we use x-ray photoelectron spectroscopy from a liquid microjet to measure the absolute surface potentials of silica nanoparticles dispersed in aqueous electrolytes. We quantitatively determine the impact of specific cations (Li^{+}, Na^{+}, K^{+}, and Cs^{+} in chloride electrolytes on the surface potential, the location of the shear plane, and the capacitance of the Stern layer. We find that the magnitude of the surface potential increases linearly with the hydrated-cation radius. Interpreting our data using the simplest assumptions and most straightforward understanding of Gouy-Chapman-Stern theory reveals a Stern layer whose thickness corresponds to a single layer of water molecules hydrating the silica surface, plus the radius of the hydrated cation. These results subject electrical double-layer theories to direct and falsifiable tests to reveal a physically intuitive and quantitatively verified picture of the Stern layer that is consistent across multiple electrolytes and solution conditions.

  14. Determination of Surface Potential and Electrical Double-Layer Structure at the Aqueous Electrolyte-Nanoparticle Interface

    Science.gov (United States)

    Brown, Matthew A.; Abbas, Zareen; Kleibert, Armin; Green, Richard G.; Goel, Alok; May, Sylvio; Squires, Todd M.

    2016-01-01

    The structure of the electrical double layer has been debated for well over a century, since it mediates colloidal interactions, regulates surface structure, controls reactivity, sets capacitance, and represents the central element of electrochemical supercapacitors. The surface potential of such surfaces generally exceeds the electrokinetic potential, often substantially. Traditionally, a Stern layer of nonspecifically adsorbed ions has been invoked to rationalize the difference between these two potentials; however, the inability to directly measure the surface potential of dispersed systems has rendered quantitative measurements of the Stern layer potential, and other quantities associated with the outer Helmholtz plane, impossible. Here, we use x-ray photoelectron spectroscopy from a liquid microjet to measure the absolute surface potentials of silica nanoparticles dispersed in aqueous electrolytes. We quantitatively determine the impact of specific cations (Li+ , Na+ , K+ , and Cs+ ) in chloride electrolytes on the surface potential, the location of the shear plane, and the capacitance of the Stern layer. We find that the magnitude of the surface potential increases linearly with the hydrated-cation radius. Interpreting our data using the simplest assumptions and most straightforward understanding of Gouy-Chapman-Stern theory reveals a Stern layer whose thickness corresponds to a single layer of water molecules hydrating the silica surface, plus the radius of the hydrated cation. These results subject electrical double-layer theories to direct and falsifiable tests to reveal a physically intuitive and quantitatively verified picture of the Stern layer that is consistent across multiple electrolytes and solution conditions.

  15. 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

  16. Structural changes in surface layer of steel 08Kh18N10T during machining

    International Nuclear Information System (INIS)

    Palenik, J.; Vodarek, V.

    1989-01-01

    The results are reported of a study of the surface layer of steel 08Kh18N10T affected by machining. Structural changes were studied caused by finish turning and by additional roller burnishing. Multiple deformation bands were observed to occur under the given cutting conditions; they mainly consisted of deformation doublets and only in isolated cases of ε-martensite. The presence of α'-martensite was not shown in the specimen surface layer following finish turning. The deformation shear bands in the roller-burnished specimen consisted of both ε-martensite and of deformation doublets. The amount of ε-martensite in the structure was significantly higher than in the specimen worked by turning. Local presence of α'-martensite formations was observed inside the deformation bands. It thus follows that roller burnishing is unsuitable as part of the manufacture of components from steel 08Kh18N10T. (J.B.). 5 figs., 1 tab., 9 refs

  17. 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

  18. Molecular dynamics study of Pb-substituted Cu(1 0 0) surface layers

    Energy Technology Data Exchange (ETDEWEB)

    Evangelakis, G.A. [Department of Physics, University of Ioannina, PO Box 1186, Ioannina 45110 (Greece); Pontikis, V., E-mail: Vassilis.pontikis@cea.f [Laboratoire des Solides Irradies, CEA-DRECAM, 91191 Gif-sur-Yvette Cedex (France)

    2009-08-26

    Using molecular dynamics (MD) and phenomenological n-body potentials from the literature, we have studied the structure of the uppermost layers of low-index surfaces in copper after partial substitution of copper by lead atoms at randomly selected sites. We found that lead atoms substituting copper strongly perturb the positions of nearest and of next-nearest neighbors thus triggering the setup of a disordered, nanometer-thick amorphous-like surface layer. Equilibrium atomic density profiles, computed along the [1 0 0] crystallographic direction, show that amorphous overlayers are largely metastable whereas the system displays a structured compositional profile of lead segregating at the interfaces. Similarities between our results and experimental findings are briefly discussed.

  19. Molecular dynamics study of Pb-substituted Cu(1 0 0) surface layers

    International Nuclear Information System (INIS)

    Evangelakis, G.A.; Pontikis, V.

    2009-01-01

    Using molecular dynamics (MD) and phenomenological n-body potentials from the literature, we have studied the structure of the uppermost layers of low-index surfaces in copper after partial substitution of copper by lead atoms at randomly selected sites. We found that lead atoms substituting copper strongly perturb the positions of nearest and of next-nearest neighbors thus triggering the setup of a disordered, nanometer-thick amorphous-like surface layer. Equilibrium atomic density profiles, computed along the [1 0 0] crystallographic direction, show that amorphous overlayers are largely metastable whereas the system displays a structured compositional profile of lead segregating at the interfaces. Similarities between our results and experimental findings are briefly discussed.

  20. The influence of various cooling rates during laser alloying on nodular iron surface layer

    Science.gov (United States)

    Paczkowska, Marta; Makuch, Natalia; Kulka, Michał

    2018-06-01

    The results of research referring to modification of the nodular iron surface layer by laser alloying with cobalt were presented. The aim of this study was to analyze the possibilities of cobalt implementation into the surface layer of nodular iron in various laser heat treatment conditions (by generating different cooling rates of melted surface layer). The modified surface layer of nodular iron was analyzed with OM, SEM, TEM, XRD, EDS and Vickers microhardness tester. The modified surface layer of nodular iron after laser alloying consisted of: the alloyed zone (melted with cobalt), the transition zone and the hardened zone from solid state. The alloyed zone was characterized by higher microstructure homogeneity - in contrast to the transition and the hardened zones. All the alloyed zones contained a dendritic microstructure. Dendrites consisted of martensite needles and retained austenite. Cementite was also detected. It was stated, that due to similar dimension of iron and cobalt atoms, their mutual replacement in the crystal lattice could occur. Thus, formation of phases based on α solution: Co-Fe (44-1433) could not be excluded. Although cobalt should be mostly diluted in solid solutions (because of its content in the alloyed zone), the other newly formed phases as Co (ε-hex.), FeC and cobalt carbides: Co3C, CoC0.25 could be present in the alloyed zones as a result of unique microstructure creation during laser treatment. Pearlite grains were observed in the zone, formed using lower power density of the laser beam and its longer exposition time. Simply, such conditions resulted in the cooling rate which was lower than critical cooling rate. The alloyed zones, produced at a higher cooling rate, were characterized by better microstructure homogeneity. Dendrites were finer in this case. This could result from a greater amount of crystal nuclei appearing at higher cooling rate. Simultaneously, the increased amount of γ-Fe and Fe3C precipitates was expected in

  1. 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.

  2. Modelling of surface fluxes and Urban Boundary Layer over an old mediterannean city core

    Science.gov (United States)

    Lemonsu, A.; Masson, V.; Grimmond, Cs. B.

    2003-04-01

    In the frameworks of the UBL(Urban Boundary Layer)-ESCOMPTE campaign, the Town Energy Balance (TEB) model was run in off-line mode for Marseille. TEB's performance is evaluated with observations of surface temperatures and surface energy balance fluxes collected during the campaign. Parameterization improvements allow to better represent the energy exchanges between the air inside the canyon and the atmosphere above the roof level. Then, high resolution Méso-NH simulations are done to study the 3-D structure and the evolution of the Urban Boundary Layer (UBL) over Marseille. Will will give a special attention to the impact of the seabord effects (sea-breeze circulation) on the UBL.

  3. Analysis of adsorption behavior of cations onto quartz surface by electrical double-layer model

    International Nuclear Information System (INIS)

    Kitamura, Akira; Yamamoto, Tadashi; Fujiwara, Kenso; Nishikawa, Sataro; Moriyama, Hirotake

    1999-01-01

    In a study of the adsorption behavior of cations onto quartz, the distribution coefficient of a variety of cations was determined using the batch method, and using the titration method, the surface charge densities of quartz in a number of electrolyte solutions. The two values thus determined were analyzed applying the electrical double-layer model, from which optimum parameter values were derived for double-layer electrostatics and intrinsic adsorption equilibrium constants. Based on these parameter values, the mechanism of cation adsorption is discussed: A key factor governing this mechanism proved to be the hydration behavior of cations. Consideration of the Coulomb interaction between the adsorbate ions and adsorbent surface led to the finding of a simple rule governing in common the adsorption equilibrium constants of different metal ions. (author)

  4. 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

    2017-01-01

    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 Alaskas 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-30m resolution. The fractional reduction in canopy volume ranged from 0.61 in lowland black spruce stands to 0.27 in mixed white spruce and broad leaf forest. Residual structure largely reflects standing dead trees, highlighting the influence of pre-fire forest structure on delayed carbon losses from above ground 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 severity

  5. 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.

  6. 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.

  7. 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)

  8. Tests of Parameterized Langmuir Circulation Mixing in the Oceans Surface Mixed Layer II

    Science.gov (United States)

    2017-08-11

    inertial oscillations in the ocean are governed by three-dimensional processes that are not accounted for in a one-dimensional simulation , and it was...Unlimited 52 Paul Martin (228) 688-5447 Recent large-eddy simulations (LES) of Langmuir circulation (LC) within the surface mixed layer (SML) of...used in the Navy Coastal Ocean Model (NCOM) and tested for (a) a simple wind-mixing case, (b) simulations of the upper ocean thermal structure at Ocean

  9. The effect of a defective BSF layer on solar cell open circuit voltage. [Back Surface Field

    Science.gov (United States)

    Weizer, V. G.

    1985-01-01

    A straightforward analysis of special limiting cases has permitted the determination of the range of possible open circuit voltage losses due to a defective BSF (back surface field) layer. An important result of the analysis is the finding that it is possible to have a fully effective BSF region, regardless of the spatial distribution of the defective areas, as long as the total defective area is reduced below certain limits. Distributed defects were found to be much more harmful than lumped defects.

  10. Magnetically dead layers at sp-impurity-decorated grain boundaries and surfaces in nickel

    Czech Academy of Sciences Publication Activity Database

    Všianská, Monika; Šob, Mojmír

    2011-01-01

    Roč. 84, č. 1 (2011), Art.n. 014418 ISSN 1098-0121 R&D Projects: GA AV ČR IAA100100920; GA ČR GD106/09/H035 Institutional research plan: CEZ:AV0Z20410507 Keywords : magnetically dead layers * sp-impurity-decorated grain boundaries and surfaces * nickel Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.691, year: 2011

  11. 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

  12. Color surface-flow visualization of fin-generated shock wave boundary-layer interactions

    Science.gov (United States)

    Lu, F. K.; Settles, G. S.

    1990-03-01

    Kerosene-lampblack mixtures with addition of a ground colored chalk were used in an experiment on visualizing surface flows of swept shock boundary-layer interactions. The results show that contrasting colors intensify the visualization of different regions of the interaction surface, and help the eye in following the fine streaks to locate the upstream influence. The study confirms observations of the separation occurring at shock strength below accepted values. The superiority of the reported technique over the previous monochrome technique is demonstrated.

  13. 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.

  14. Blistering in a porous surface layer of materials. [He ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Afrikanov, I.N.; Vladimirov, B.G.; Guseva, M.I.; Ivanov, S.M.; Martynenko, Yu.V.; Nikol' skij, Yu.V.; Ryazanov, A.I.

    1981-03-01

    The effect of porous structure on the nature and rate of radiation erosion during implantation of helium ions into nickel and the OKh15N15M3B stainless steel is studied. The investigation results showed sharp dependence of the erosion rate due to blistering on the dimension and density of pores in the by-surface layer. The rate of the surface erosion increased in one order as compared with the control specimens without pores at 1% swelling for stainless steel and 4% for nickel.

  15. 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...

  16. 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.

  17. Surface diffusion coefficient of Au atoms on single layer graphene grown on Cu

    Energy Technology Data Exchange (ETDEWEB)

    Ruffino, F., E-mail: francesco.ruffino@ct.infn.it; Cacciato, G.; Grimaldi, M. G. [Dipartimento di Fisica ed Astronomia-Universitá di Catania, via S. Sofia 64, 95123 Catania, Italy and MATIS IMM-CNR, via S. Sofia 64, 95123 Catania (Italy)

    2014-02-28

    A 5 nm thick Au film was deposited on single layer graphene sheets grown on Cu. By thermal processes, the dewetting phenomenon of the Au film on the graphene was induced so to form Au nanoparticles. The mean radius, surface-to-surface distance, and surface density evolution of the nanoparticles on the graphene sheets as a function of the annealing temperature were quantified by scanning electron microscopy analyses. These quantitative data were analyzed within the classical mean-field nucleation theory so to obtain the temperature-dependent Au atoms surface diffusion coefficient on graphene: D{sub S}(T)=[(8.2±0.6)×10{sup −8}]exp[−(0.31±0.02(eV)/(at) )/kT] cm{sup 2}/s.

  18. Influence of physicochemical factors on microplasticity of surface layer of molybdenum single crystals

    International Nuclear Information System (INIS)

    Savenko, V.I.; Kuchumova, V.M.; Kochanova, L.A.; Shchukin, E.D.

    1984-01-01

    Microplasticity of the surface layer (not more than 10 μm) of a molybdenum monocrystal was investigated by the methods of ultramicrosclerometry and microindentation. Tests of samples with clean surface and with monolayer octadecylamine film were conducted in the air at 60% relative humidity. Microplastic deformation of samples was conducted by slipping of garnet needle on crystal surface with 10 -6 -10 -2 N force. Sclerograms represented etch pits corresponding to dislocation discharges on the surface. The linear density of dislocations in indentor routes and statistic factor (the probability of plastic deformation at assigned force) were used as microplasticity characteristics. It was revealed that plane (111) is the most prone to plastic damage and plane (100) is the least prone to it

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

    KAUST Repository

    Mansour, Ahmed; Kirmani, Ahmad R.; Barlow, Stephen; Marder, Seth R.; Amassian, Aram

    2017-01-01

    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.

  20. 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.

  1. Preparation of Copper and Chromium Alloyed Layers on Pure Titanium by Plasma Surface Alloying Technology

    Science.gov (United States)

    He, Xiaojing; Li, Meng; Wang, Huizhen; Zhang, Xiangyu; Tang, Bin

    2015-05-01

    Cu-Cr alloyed layers with different Cu and Cr contents on pure titanium were obtained by means of plasma surface alloying technology. The microstructure, chemical composition and phase composition of Cu-Cr alloyed layers were analyzed by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD), respectively. The experimental results demonstrate that the alloyed layers are bonded strongly to pure titanium substrate and consist of unbound Ti, CuTi, Cu3Ti, CuTi3 and Cr2Ti. The thickness of Cu5Cr5 and Cu7Cr3 alloyed layer are about 18 μm and 28 μm, respectively. The antibacterial properties against gram-negative Escherichia coli (E.coli, ATCC10536) and gram-positive Staphylococcus aureus (S. aureus, ATCC6538) of untreated pure titanium and Cu-Cr alloyed specimen were investigated by live/dead fluorescence staining method. The study shows that Cu-Cr alloyed layers exhibit excellent antibacterial activities against both E.coli and S.aureus within 24 h, which may be attributed to the formation of Cu-containing phases.

  2. A numerical investigation of the impact of surface topology on laminar boundary layers

    Science.gov (United States)

    Beratlis, Nikolaos; Squires, Kyle; Balaras, Elias

    2015-11-01

    Surface topology, such as dimples or trip wires, has been utilized in the past for passive separation control over bluff bodies. The majority of the work, however, has focused on the indirect effects on the drag and lift forces, while the details of the impact on the boundary layer evolution are not well understood. Here we report a series of DNS of flow over a single row of spherical and hexagonal dimples, as well as, circular grooves. The Reynolds number and the thickness of the incoming laminar boundary layer is carefully controlled. In all cases transition to turbulence downstream of the elements comes with reorientation of the spanwise vorticity into hairpin like vortices. Although qualitatively the transition mechanism amongst different dimples and grooves is similar, important quantitative differences exist: two-dimensional geometries such as the groove, are more stable than three-dimensional geometries. In addition, it was found that the cavity geometry controls the initial thickness of the boundary layer and practically results in a shift of the virtual origin of the turbulent boundary layer. Important differences in the momentum transport downstream of the dimples exist, but in all cases the boundary layer evolves in a self-similar manner.

  3. Investigation of surface charge density on solid–liquid interfaces by modulating the electrical double layer

    International Nuclear Information System (INIS)

    Moon, Jong Kyun; Song, Myung Won; Pak, Hyuk Kyu

    2015-01-01

    A solid surface in contact with water or aqueous solution usually carries specific electric charges. These surface charges attract counter ions from the liquid side. Since the geometry of opposite charge distribution parallel to the solid–liquid interface is similar to that of a capacitor, it is called an electrical double layer capacitor (EDLC). Therefore, there is an electrical potential difference across an EDLC in equilibrium. When a liquid bridge is formed between two conducting plates, the system behaves as two serially connected EDLCs. In this work, we propose a new method for investigating the surface charge density on solid–liquid interfaces. By mechanically modulating the electrical double layers and simultaneously applying a dc bias voltage across the plates, an ac electric current can be generated. By measuring the voltage drop across a load resistor as a function of bias voltage, we can study the surface charge density on solid–liquid interfaces. Our experimental results agree very well with the simple equivalent electrical circuit model proposed here. Furthermore, using this method, one can determine the polarity of the adsorbed state on the solid surface depending on the material used. We expect this method to aid in the study of electrical phenomena on solid–liquid interfaces. (paper)

  4. Mg-Fe-mixed oxides derived from layered double hydroxides: A study of the surface properties

    Directory of Open Access Journals (Sweden)

    Marinković-Nedučin Radmila P.

    2011-01-01

    Full Text Available The influence of surface properties on the selectivity of the synthesized catalysts was studied, considering that their selectivity towards particular hydrocarbons is crucial for their overall activity in the chosen Fischer- -Tropsch reaction. Magnesium- and iron-containing layered double hydroxides (LDH, with the general formula: [Mg1-xFex(OH2](CO3x/2?mH2O, x = = n(Fe/(n(Mg+n(Fe, synthesized with different Mg/Fe ratio and their thermally derived mixed oxides were investigated. Magnesium was chosen because of its basic properties, whereas iron was selected due to its well-known high Fischer-Tropsch activity, redox properties and the ability to form specific active sites in the layered LDH structure required for catalytic application. The thermally less stable multiphase system (synthesized outside the optimal single LDH phase range with additional Fe-phase, having a lower content of surface acid and base active sites, a lower surface area and smaller fraction of smaller mesopores, showed higher selectivity in the Fischer-Tropsch reaction. The results of this study imply that the metastability of derived multiphase oxides structure has a greater influence on the formation of specific catalyst surface sites than other investigated surface properties.

  5. Lesion dehydration rate changes with the surface layer thickness during enamel remineralization

    Science.gov (United States)

    Chang, Nai-Yuan N.; Jew, Jamison M.; Fried, Daniel

    2018-02-01

    A transparent highly mineralized outer surface zone is formed on caries lesions during remineralization that reduces the permeability to water and plaque generated acids. However, it has not been established how thick the surface zone should be to inhibit the penetration of these fluids. Near-IR (NIR) reflectance coupled with dehydration can be used to measure changes in the fluid permeability of lesions in enamel and dentin. Based on our previous studies, we postulate that there is a strong correlation between the surface layer thickness and the rate of dehydration. In this study, the rates of dehydration for simulated lesions in enamel with varying remineralization durations were measured. Reflectance imaging at NIR wavelengths from 1400-2300 nm, which coincides with higher water absorption and manifests the greatest sensitivity to contrast changes during dehydration measurements, was used to image simulated enamel lesions. The results suggest that the relationship between surface zone thickness and lesion permeability is highly non-linear, and that a small increase in the surface layer thickness may lead to a significant decrease in permeability.

  6. 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.

  7. CWEX: Crop/wind-energy experiment: Observations of surface-layer, boundary-layer and mesoscale interactions with a wind farm

    Science.gov (United States)

    Large wind turbines perturb mean and turbulent wind characteristics, which modify fluxes between the vegetated surface and the lower boundary layer. While simulations have suggested that wind farms could create significant changes in surface fluxes of heat, momentum, moisture, and CO2 over hundreds ...

  8. Crop/Wind-energy Experiment (CWEX): Observations of surface-layer, boundary-layer and mesoscale interactions with a wind farm

    Science.gov (United States)

    Perturbations of mean and turbulent wind characteristics by large wind turbines modify fluxes between the vegetated surface and the lower boundary layer. While simulations have suggested that wind farms could significantly change surface fluxes of heat, momentum, moisture, and CO2 over hundreds of s...

  9. Microstructures of tribologically modified surface layers in two-phase alloys

    International Nuclear Information System (INIS)

    Figueroa, C G; Ortega, I; Jacobo, V H; Ortiz, A; Bravo, A E; Schouwenaars, R

    2014-01-01

    When ductile alloys are subject to sliding wear, small increments of plastic strain accumulate into severe plastic deformation and mechanical alloying of the surface layer. The authors constructed a simple coaxial tribometer, which was used to study this phenomenon in wrought Al-Sn and cast Cu-Mg-Sn alloys. The first class of materials is ductile and consists of two immiscible phases. Tribological modification is observed in the form of a transition zone from virgin material to severely deformed grains. At the surface, mechanical mixing of both phases competes with diffusional unmixing. Vortex flow patterns are typically observed. The experimental Cu-Mg-Sn alloys are ductile for Mg-contents up to 2 wt% and consist of a- dendrites with a eutectic consisting of a brittle Cu 2 Mg-matrix with α-particles. In these, the observations are similar to the Al-Sn Alloys. Alloys with 5 wt% Mg are brittle due to the contiguity of the eutectic compound. Nonetheless, under sliding contact, this compound behaves in a ductile manner, showing mechanical mixing of a and Cu 2 Mg in the top layers and a remarkable transition from a eutectic to cellular microstructure just below, due to severe shear deformation. AFM-observations allow identifying the mechanically homogenized surface layers as a nanocrystalline material with a cell structure associated to the sliding direction

  10. 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

  11. 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

  12. Inverse estimation for temperatures of outer surface and geometry of inner surface of furnace with two layer walls

    International Nuclear Information System (INIS)

    Chen, C.-K.; Su, C.-R.

    2008-01-01

    This study provides an inverse analysis to estimate the boundary thermal behavior of a furnace with two layer walls. The unknown temperature distribution of the outer surface and the geometry of the inner surface were estimated from the temperatures of a small number of measured points within the furnace wall. The present approach rearranged the matrix forms of the governing differential equations and then combined the reversed matrix method, the linear least squares error method and the concept of virtual area to determine the unknown boundary conditions of the furnace system. The dimensionless temperature data obtained from the direct problem were used to simulate the temperature measurements. The influence of temperature measurement errors upon the precision of the estimated results was also investigated. The advantage of this approach is that the unknown condition can be directly solved by only one calculation process without initially guessed temperatures, and the iteration process of the traditional method can be avoided in the analysis of the heat transfer. Therefore, the calculation in this work is more rapid and exact than the traditional method. The result showed that the estimation error of the geometry increased with increasing distance between measured points and inner surface and in preset error, and with decreasing number of measured points. However, the geometry of the furnace inner surface could be successfully estimated by only the temperatures of a small number of measured points within and near the outer surface under reasonable preset error

  13. Evaluation of surface layer flux parameterizations using in-situ observations

    Science.gov (United States)

    Katz, Jeremy; Zhu, Ping

    2017-09-01

    Appropriate calculation of surface turbulent fluxes between the atmosphere and the underlying ocean/land surface is one of the major challenges in geosciences. In practice, the surface turbulent fluxes are estimated from the mean surface meteorological variables based on the bulk transfer model combined with the Monnin-Obukhov Similarity (MOS) theory. Few studies have been done to examine the extent to which such a flux parameterization can be applied to different weather and surface conditions. A novel validation method is developed in this study to evaluate the surface flux parameterization using in-situ observations collected at a station off the coast of Gulf of Mexico. The main findings are: (a) the theoretical prediction that uses MOS theory does not match well with those directly computed from the observations. (b) The largest spread in exchange coefficients is shown in strong stable conditions with calm winds. (c) Large turbulent eddies, which depend strongly on the mean flow pattern and surface conditions, tend to break the constant flux assumption in the surface layer.

  14. Binary Colloidal Crystal Layers as Platforms for Surface Patterning of Puroindoline-Based Antimicrobial Peptides.

    Science.gov (United States)

    Boden, Andrew; Bhave, Mrinal; Wang, Peng-Yuan; Jadhav, Snehal; Kingshott, Peter

    2018-01-24

    The ability of bacteria to form biofilms and the emergence of antibiotic-resistant strains have prompted the need to develop the next generation of antibacterial coatings. Antimicrobial peptides (AMPs) are showing promise as molecules that can address these issues, especially if used when immobilized as a surface coating. We present a method that explores how surface patterns together with the selective immobilization of an AMP called PuroA (FPVTWRWWKWWKG-NH 2 ) can be used to both kill bacteria and also as a tool to study bacterial attachment mechanisms. Surface patterning is achieved using stabilized self-assembled binary colloidal crystal (BCC) layers, allowing selective PuroA immobilization to carboxylated particles using N-(3-dimethylaminopropyl)-N'-ethyl carbodiimide (EDC) hydrochloride/N-hydroxysuccinimide (NHS) coupling chemistry. Covalent immobilization of PuroA was compared with physical adsorption (i.e., without the addition of EDC/NHS). The AMP-functionalized colloids and BCC layers were characterized by X-ray photoelectron spectroscopy, ζ potentials, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Surface antimicrobial activity was assessed by viability assays using Escherichia coli. MALDI-TOF MS analysis revealed that although not all of PuroA was successfully covalently immobilized, a relatively low density of PuroA (1.93 × 10 13 molecules/cm 2 and 7.14 × 10 12 molecules/cm 2 for covalent and physical immobilization, respectively) was found to be sufficient at significantly decreasing the viability of E. coli by 70% when compared to that of control samples. The findings provide a proof of concept that BCC layers are a suitable platform for the patterned immobilization of AMPs and the importance of ascertaining the success of small-molecule grafting reactions using surface-MALDI, something that is often assumed to be successful in the field.

  15. 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

  16. Propagation behavior of two transverse surface waves in a three-layer piezoelectric/piezomagnetic structure

    Science.gov (United States)

    Nie, Guoquan; Liu, Jinxi; Liu, Xianglin

    2017-10-01

    Propagation of transverse surface waves in a three-layer system consisting of a piezoelectric/piezomagnetic (PE/PM) bi-layer bonded on an elastic half-space is theoretically investigated in this paper. Dispersion relations and mode shapes for transverse surface waves are obtained in closed form under electrically open and shorted boundary conditions at the upper surface. Two transverse surface waves related both to Love-type wave and Bleustein-Gulyaev (B-G) type wave propagating in corresponding three-layer structure are discussed through numerically solving the derived dispersion equation. The results show that Love-type wave possesses the property of multiple modes, it can exist all of the values of wavenumber for every selected thickness ratios regardless of the electrical boundary conditions. The presence of PM interlayer makes the phase velocity of Love-type wave decrease. There exist two modes allowing the propagation of B-G type wave under electrically shorted circuit, while only one mode appears in the case of electrically open circuit. The modes of B-G type wave are combinations of partly normal dispersion and partly anomalous dispersion whether the electrically open or shorted. The existence range of mode for electrically open case is greatly related to the thickness ratios, with the thickness of PM interlayer increasing the wavenumber range for existence of B-G type wave quickly shortened. When the thickness ratio is large enough, the wavenumber range of the second mode for electrically shorted circuit is extremely narrow which can be used to remove as an undesired mode. The propagation behaviors and mode shapes of transverse surface waves can be regulated by the modification of the thickness of PM interlayer. The obtained results provide a theoretical prediction and basis for applications of PE-PM composites and acoustic wave devices.

  17. Ellipsometry measurements of thickness of oxide and water layers on spherical and flat silicon surfaces

    International Nuclear Information System (INIS)

    Kenny, M.J.; Netterfield, R.; Wielunski, L.S.

    1998-01-01

    Full text: Ellipsometry has been used to measure the thickness of oxide layers on single crystal silicon surfaces, both flat and spherical and also to measure the extent of adsorption of moisture on the surface as a function of partial water vapour pressure. The measurements form part of an international collaborative project to make a precise determination of the Avogadro constant (ΔN A /N A -8 ) which will then be used to obtain an absolute definition of the kilogram, rather than one in terms of an artefact. Typically the native oxide layer on a cleaned silicon wafer is about 2 nm thick. On a polished sphere this oxide layer is typically 8 to 10 nm thick, the increased thickness being attributed to parameters related to the polishing process. Ellipsometry measurements on an 89 mm diameter polished silicon sphere at both VUW and CSIRO indicated a SiO 2 layer at 7 to 10 nm thick. It was observed that this thickness varied regularly. The crystal orientation of the sphere was determined using electron patterns generated from an electron microscope and the oxide layer was then measured through 180 arcs of great circles along (110) and (100) planes. It was observed that the thickness varied systematically with orientation. The minimum thickness was 7.4 nm at the axis (softest direction in silicon) and the greatest thickness was 9.5 nm at the axis (hardest direction in silicon). This is similar to an orientation dependent cubic pattern which has been observed to be superimposed on polished silicon spheres. At VUW, the sphere was placed in an evacuated bell jar and the ellipsometry signal was observed as the water vapour pressure was progressively increased up to saturation. The amount of water vapour adsorbed at saturation was one or two monolayers, indicating that the sphere does not wet

  18. 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.

  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. Surface layer and bloom dynamics observed with the Prince William Sound Autonomous Profiler

    Science.gov (United States)

    Campbell, R. W.

    2016-02-01

    As part of a recent long term monitoring effort, deployments of a WETLabs Autonomous Moored Profiler (AMP) began Prince William Sound (PWS) in 2013. The PWS AMP consists of a positively buoyant instrument frame, with a winch and associated electronics that profiles the frame from a park depth (usually 55 m) to the surface by releasing and retrieving a thin UHMWPE tether; it generally conducts a daily cast and measures temperature, salinity, chlorophyll-a fluorescence, turbidity, and oxygen and nitrate concentrations. Upward and downward looking ADCPs are mounted on a float below the profiler, and an in situ plankton imager is in development and will be installed in 2016. Autonomous profilers are a relatively new technology, and early deployments experienced a number of failures from which valuable lessons may be learned. Nevertheless, an unprecedented time series of the seasonal biogeochemical procession in the surface waters coastal Gulf of Alaska was collected in 2014 and 2015. The northern Gulf of Alaska has experienced a widespread warm anomaly since early 2014, and surface layer temperature anomalies in PWS were strongly positive during winter 2014. The spring bloom observed by the profiler began 2-3 weeks earlier than average, with surface nitrate depleted by late April. Although surface temperatures were still above average in 2015, bloom timing was much later, with a short vigorous bloom in late April and a subsurface bloom in late May that coincided with significant nitrate drawdown. As well as the vernal blooms, wind-driven upwelling events lead to several small productivity pulses that were evident in changes in nitrate and oxygen concentrations, and chlorophyll-a fluorescence. As well as providing a mechanistic understanding of surface layer biogeochemistry, high frequency observations such as these put historical observations in context, and provide new insights into the scales of variability in the annual cycles of the surface ocean in the North

  1. Characteristics of the surface layer of barium strontium titanate thin films deposited by laser ablation

    International Nuclear Information System (INIS)

    Craciun, V.; Singh, R. K.

    2000-01-01

    Ba 0.5 Sr 0.5 TiO 3 (BST) thin films grown on Si by an in situ ultraviolet-assisted pulsed laser deposition (UVPLD) technique exhibited significantly higher dielectric constant and refractive index values and lower leakage current densities than films grown by conventional PLD under similar conditions. X-ray photoelectron spectroscopy (XPS) investigations have shown that the surface layer of the grown films contained, besides the usual BST perovskite phase, an additional phase with Ba atoms in a different chemical state. PLD grown films always exhibited larger amounts of this phase, which was homogeneously mixed with the BST phase up to several nm depth, while UVPLD grown films exhibited a much thinner (∼1 nm) and continuous layer. The relative fraction of this phase was not correlated with the amount of C atoms present on the surface. Fourier transform infrared spectroscopy did not find any BaCO 3 contamination layer, which was believed to be related to this new phase. X-ray diffraction measurement showed that although PLD grown films contained less oxygen atoms, the lattice parameter was closer to the bulk value than that of UVPLD grown films. After 4 keV Ar ion sputtering for 6 min, XPS analysis revealed a small suboxide Ba peak for the PLD grown films. This finding indicates that the average Ba-O bonds are weaker in these films, likely due to the presence of oxygen vacancies. It is suggested here that this new Ba phase corresponds to a relaxed BST surface layer. (c) 2000 American Institute of Physics

  2. Characteristics of the surface layer of barium strontium titanate thin films deposited by laser ablation

    Science.gov (United States)

    Craciun, V.; Singh, R. K.

    2000-04-01

    Ba0.5Sr0.5TiO3 (BST) thin films grown on Si by an in situ ultraviolet-assisted pulsed laser deposition (UVPLD) technique exhibited significantly higher dielectric constant and refractive index values and lower leakage current densities than films grown by conventional PLD under similar conditions. X-ray photoelectron spectroscopy (XPS) investigations have shown that the surface layer of the grown films contained, besides the usual BST perovskite phase, an additional phase with Ba atoms in a different chemical state. PLD grown films always exhibited larger amounts of this phase, which was homogeneously mixed with the BST phase up to several nm depth, while UVPLD grown films exhibited a much thinner (˜1 nm) and continuous layer. The relative fraction of this phase was not correlated with the amount of C atoms present on the surface. Fourier transform infrared spectroscopy did not find any BaCO3 contamination layer, which was believed to be related to this new phase. X-ray diffraction measurement showed that although PLD grown films contained less oxygen atoms, the lattice parameter was closer to the bulk value than that of UVPLD grown films. After 4 keV Ar ion sputtering for 6 min, XPS analysis revealed a small suboxide Ba peak for the PLD grown films. This finding indicates that the average Ba-O bonds are weaker in these films, likely due to the presence of oxygen vacancies. It is suggested here that this new Ba phase corresponds to a relaxed BST surface layer.

  3. Nanoscale imaging of surface piezoresponse on GaN epitaxial layers

    International Nuclear Information System (INIS)

    Stoica, T.; Calarco, R.; Meijers, R.; Lueth, H.

    2007-01-01

    Surfaces of GaN films were investigated by atomic force microscopy (AFM) with implemented piezoelectric force microscopy technique. A model of PFM based on the surface depletion region in GaN films is discussed. The local piezoelectric effect of the low frequency regime was found to be in phase with the applied voltage on large domains, corresponding to a Ga-face of the GaN layer. Low piezoresponse is obtained within the inter-domain regions. The use of frequencies near a resonance frequency enhances very much the resolution of piezo-imaging, but only for very low scanning speed the piezo-imaging can follow the local piezoelectric effect. An inversion of the PFM image contrast is obtained for frequencies higher than the resonance frequencies. The effect of a chemical surface treatment on the topography and the piezoresponse of the GaN films was also investigated. Textured surfaces with very small domains were observed after the chemical treatment. For this kind of surfaces, piezo-induced torsion rather than bending of the AFM cantilever dominates the contrast of the PFM images. A small memory effect was observed, and explained by surface charging and confinement of the piezoelectric effect within the carrier depletion region at the GaN surface

  4. Stability studies of plasma modification effects of polylactide and polycaprolactone surface layers

    Energy Technology Data Exchange (ETDEWEB)

    Moraczewski, Krzysztof, E-mail: kmm@ukw.edu.pl [Kazimierz Wielki University, Chodkiewicza 30, 85-064 Bydgoszcz (Poland); Stepczyńska, Magdalena [Kazimierz Wielki University, Chodkiewicza 30, 85-064 Bydgoszcz (Poland); Malinowski, Rafał [Institute for Engineering of Polymer Materials and Dyes, Marii Skłodowskiej-Curie 55, 87‐100 Toruń (Poland); Rytlewski, Piotr; Jagodziński, Bartłomiej; Żenkiewicz, Marian [Kazimierz Wielki University, Chodkiewicza 30, 85-064 Bydgoszcz (Poland)

    2016-07-30

    Highlights: • Plasma modification affects surface roughness, wettability and surface energy. • Polylactide and polycaprolactone aging causes decay of the modification effects. • Changes in the surface characteristic and wettability deterioration were observed. • The decay occurs due to migration of low molecular weight molecules to the surface. • Plasma modification effect lasts longer in the case of polycaprolactone. - Abstract: The article presents results of research on the stability of oxygen plasma modification effects of polylactide and polycaprolactone surface layers. The modified samples were aged for three, six or nine weeks. The studies were carried out using scanning electron microscopy, goniometry and Fourier transform infrared spectroscopy. Studies have shown that the plasma modification has significant impact on the geometric structure and chemical composition of the surface, wettability and surface energy of tested polymers. The modification effects are not permanent. It has been observed that over time the effects of plasma modification fade. Studies have shown that modifying effect lasts longer in the case of polycaprolactone.

  5. 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

  6. Sliding behavior of oil droplets on nanosphere stacking layers with different surface textures

    International Nuclear Information System (INIS)

    Hsieh, Chien-Te; Wu, Fang-Lin; Chen, Wei-Yu

    2010-01-01

    Two facile coating techniques, gravitational sediment and spin coating, were applied for the creation of silica sphere stacking layers with different textures onto glass substrates that display various sliding abilities toward liquid drops with different surface tensions, ranged from 25.6 to 72.3 mN/m. The resulting silica surface exhibits oil repellency, long-period durability > 30 days, and oil sliding capability. The two-tier texture offers a better roll-off ability toward liquid drops with a wide range of γ L , ranged from 30.2 to 72.3 mN/m, i.e., when the sliding angle (SA) ad ) appears to describe the sliding behavior within the W ad region: 2.20-3.03 mN/m. The smaller W ad , the easier drop sliding (i.e., the smaller SA value) takes place on the surfaces. The W ad value ∼3.03 mN/m shows a critical kinetic barrier for drop sliding on the silica surfaces from stationary to movement states. This work proposes a mathematical model to simulate the sliding behavior of oil drops on a nanosphere stacking layer, confirming the anti-oil contamination capability.

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

    Science.gov (United States)

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

    2015-02-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-02-23

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

  9. Characterizing boundary layer height using surface and column measurements of NO2 and formaldehyde

    Science.gov (United States)

    Valin, L.; Szykman, J.; Long, R.; Whitehill, A.; Williams, D. J.; Knepp, T. N.; Crawford, J. H.; Al-Saadi, J. A.; Judd, L.; Brown, S.; Matichuk, R.; Tonnesen, G.; Appel, W.; Hogrefe, C.; Abuhassan, N.; Cede, A.; Spinei, E.; Herman, J. R.; Swap, R.; Cohen, R. C.; Fried, A.; Weinheimer, A. J.

    2017-12-01

    The rate of vertical mixing near the surface determines the rate of human exposure to emitted pollutants and also influences the rate at which ozone and particulate matter are formed. To characterize the variability of atmospheric composition near the surface and above, the EPA Office of Research and Development has deployed instruments to measure surface and column concentrations of NO2, an emitted species, and formaldehyde (HCHO) during KORUS-AQ (May - June 2016, Seoul, Korea), UWFPS (Jan-Feb 2016, Salt Lake City) and LMOS (May - June, 2017, Lake Michigan). We compare the mixed layer height determined by aerosol backscatter profiles to a value determined by dividing the NO2 and HCHO column density (molecule cm-2) by its surface concentration (molecule cm-3), using linear regression to remove influence of layers aloft (y-intercept), such as subtraction of the stratospheric NO2 column. We evaluate our findings by using aircraft soundings of NO2 and HCHO and discuss the implications with respect to photochemical transport modeling results from CMAQ and space-based satellite retrievals. Finally we discuss an overall strategy to make these measurements part of routine monitoring at Photochemical Assessment Monitoring System locations (PAMS).

  10. 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

  11. Effects of Surface Roughness and Mechanical Properties of Cover-Layer on Near-Field Optical Recording

    Science.gov (United States)

    Kim, Jin-Hong; Lee, Jun-Seok; Lim, Jungshik; Seo, Jung-Kyo

    2009-03-01

    Narrow gap distance in cover-layer incident near-field recording (NFR) configuration causes a collision problem in the interface between a solid immersion lens and a disk surface. A polymer cover-layer with smooth surface results in a stable gap servo while a nanocomposite cover-layer with high refractive index shows a collision problem during the gap servo test. Even though a dielectric cover-layer, in which the surface is rougher than the polymer, supplements the mechanical properties, an unclear eye pattern due to an unstable gap servo can be obtained after a chemical mechanical polishing. Not only smooth surface but also good mechanical properties of cover-layer are required for the stable gap servo in the NFR.

  12. 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

  13. 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

  14. 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

  15. 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

  16. Modeling of Waves Propagating in Water with a Crushed Ice Layer on the Free Surface

    Science.gov (United States)

    Szmidt, Kazimierz

    2017-12-01

    A transformation of gravitational waves in fluid of constant depth with a crushed ice layer floating on the free fluid surface is considered. The propagating waves undergo a slight damping along their path of propagation. The main goal of the study is to construct an approximate descriptive model of this phenomenon.With regard to small displacements of the free surface, a viscous type model of damping is considered, which corresponds to a continuous distribution of dash-pots at the free surface of the fluid. A constant parameter of the dampers is assumed in advance as known parameter of damping. This parameter may be obtained by means of experiments in a laboratory flume.

  17. 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.

  18. Influence of the electromagnetic parameters on the surface wave attenuation in thin absorbing layers

    Science.gov (United States)

    Li, Yinrui; Li, Dongmeng; Wang, Xian; Nie, Yan; Gong, Rongzhou

    2018-05-01

    This paper describes the relationships between the surface wave attenuation properties and the electromagnetic parameters of radar absorbing materials (RAMs). In order to conveniently obtain the attenuation constant of TM surface waves over a wide frequency range, the simplified dispersion equations in thin absorbing materials were firstly deduced. The validity of the proposed method was proved by comparing with the classical dispersion equations. Subsequently, the attenuation constants were calculated separately for the absorbing layers with hypothetical relative permittivity and permeability. It is found that the surface wave attenuation properties can be strongly tuned by the permeability of RAM. Meanwhile, the permittivity should be appropriate so as to maintain high cutoff frequency. The present work provides specific methods and designs to improve the attenuation performances of radar absorbing materials.

  19. Mixed convection-radiation interaction in boundary-layer flow over horizontal surfaces

    Science.gov (United States)

    Ibrahim, F. S.; Hady, F. M.

    1990-06-01

    The effect of buoyancy forces and thermal radiation on the steady laminar plane flow over an isothermal horizontal flat plate is investigated within the framework of first-order boundary-layer theory, taking into account the hydrostatic pressure variation normal to the plate. The fluid considered is a gray, absorbing-emitting but nonscattering medium, and the Rosseland approximation is used to describe the radiative heat flux in the energy equation. Both a hot surface facing upward and a cold surface facing downward are considered in the analysis. Numerical results for the local Nusselt number, the local wall shear stress, the local surface heat flux, as well as the velocity and temperature distributions are presented for gases with a Prandtl number of 0.7 for various values of the radiation-conduction parameter, the buoyancy parameter, and the temperature ratio parameter.

  20. 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.

  1. 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.

  2. Immunoevasive protein (IEP)-containing surface layer covering polydnavirus particles is essential for viral infection.

    Science.gov (United States)

    Furihata, Shunsuke; Tanaka, Kohjiro; Ryuda, Masasuke; Ochiai, Masanori; Matsumoto, Hitoshi; Csikos, Gyorge; Hayakawa, Yoichi

    2014-01-01

    Polydnaviruses (PDVs) are unique symbiotic viruses associated with parasitoid wasps: PDV particles are injected into lepidopteran hosts along with the wasp eggs and express genes that interfere with aspects of host physiology such as immune defenses and development. Recent comparative genomic studies of PDVs have significantly improved our understanding of their origin as well as the genome organization. However, the structural features of functional PDV particles remain ambiguous. To clear up the structure of Cotesia kariyai PDV (CkPDV) particles, we focused on immunoevasive protein (IEP), which is a mediator of immunoevasion by the wasp from the encapsulation reaction of the host insect's hemocytes, because it has been demonstrated to be present on the surface of the virus particle. We discovered that IEP tends to polymerize and constitutes a previously unidentified thin surface layer covering CkPDV particles. This outermost surface layer looked fragile and was easily removed from CkPVD particles by mechanical stressors such as shaking, which prevented CkPDV from expressing the encoded genes in the host target tissues such as fat body or hemocytes. Furthermore, we detected IEP homologue gene expression in the wasp's venom reservoirs, implying IEP has another unknown biological function in the wasp or parasitized hosts. Taken together, the present results demonstrated that female C. kariyai wasps produce the fragile thin layer partly composed of IEP to cover the outer surfaces of CkPDV particles; otherwise, they cannot function as infectious agents in the wasp's host. The fact that IEP family proteins are expressed in both venom reservoirs and oviducts suggests an intimate relationship between both tissues in the development of the parasitism strategy of the wasp. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. DC-to-DC converter comprising a reconfigurable capacitor unit

    NARCIS (Netherlands)

    2008-01-01

    The present invention relates to a configurable trench multi-capacitor device comprising a trench in a semiconductor substrate. The trench has a lateral extension exceeding 10 micrometer and a trench filling includes a number of at least four electrically conductive capacitor-electrode layers. A

  4. DC-to-DC converter comprising a reconfigurable capacitor unit

    NARCIS (Netherlands)

    Klootwijk, J.H.; Bergveld, H.J.; Roozeboom, F.; Reefman, D.; Ruigrok, J.

    2013-01-01

    The present invention relates to a configurable trench multi-capacitor device comprising a trench in a semiconductor substrate. The trench has a lateral extension exceeding 10 micrometer and a trench filling includes a number of at least four electrically conductive capacitor-electrode layers. A

  5. Pump-probe surface photovoltage spectroscopy measurements on semiconductor epitaxial layers

    International Nuclear Information System (INIS)

    Jana, Dipankar; Porwal, S.; Sharma, T. K.; Oak, S. M.; Kumar, Shailendra

    2014-01-01

    Pump-probe Surface Photovoltage Spectroscopy (SPS) measurements are performed on semiconductor epitaxial layers. Here, an additional sub-bandgap cw pump laser beam is used in a conventional chopped light geometry SPS setup under the pump-probe configuration. The main role of pump laser beam is to saturate the sub-bandgap localized states whose contribution otherwise swamp the information related to the bandgap of material. It also affects the magnitude of Dember voltage in case of semi-insulating (SI) semiconductor substrates. Pump-probe SPS technique enables an accurate determination of the bandgap of semiconductor epitaxial layers even under the strong influence of localized sub-bandgap states. The pump beam is found to be very effective in suppressing the effect of surface/interface and bulk trap states. The overall magnitude of SPV signal is decided by the dependence of charge separation mechanisms on the intensity of the pump beam. On the contrary, an above bandgap cw pump laser can be used to distinguish the signatures of sub-bandgap states by suppressing the band edge related feature. Usefulness of the pump-probe SPS technique is established by unambiguously determining the bandgap of p-GaAs epitaxial layers grown on SI-GaAs substrates, SI-InP wafers, and p-GaN epilayers grown on Sapphire substrates

  6. The role of Ag buffer layer in Fe islands growth on Ge (111) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Tsu-Yi, E-mail: phtifu@phy.ntnu.edu.tw; Wu, Jia-Yuan; Jhou, Ming-Kuan; Hsu, Hung-Chan [Department of Physics, National Taiwan Normal University, 88, Sec. 4, Ting-Chou Rd, Taipei 116, Taiwan (China)

    2015-05-07

    Sub-monolayer iron atoms were deposited at room temperature on Ge (111)-c(2 × 8) substrates with and without Ag buffer layers. The behavior of Fe islands growth was investigated by using scanning tunneling microscope (STM) after different annealing temperatures. STM images show that iron atoms will cause defects and holes on substrates at room temperature. As the annealing temperature rises, iron atoms pull out germanium to form various kinds of alloyed islands. However, the silver layer can protect the Ag/Ge(111)-(√3×√3) reconstruction from forming defects. The phase diagram shows that ring, dot, and triangular defects were only found on Ge (111)-c(2 × 8) substrates. The kinds of islands found in Fe/Ge system are similar to Fe/Ag/Ge system. It indicates that Ge atoms were pulled out to form islands at high annealing temperatures whether there was a Ag layer or not. But a few differences in big pyramidal or strip islands show that the silver layer affects the development of islands by changing the surface symmetry and diffusion coefficient. The structure characters of various islands are also discussed.

  7. 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

  8. 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

  9. 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; Fu, Lei; Sougrat, Rachid; Belmabkhout, Youssef; Cairns, Amy; Giannelis, Emmanuel P.; Eddaoudi, Mohamed

    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.

  10. 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

  11. Multilayer Electroactive Polymer Composite Material Comprising Carbon Nanotubes

    Science.gov (United States)

    Ounaies, Zoubeida (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Draughon, Gregory K. (Inventor)

    2009-01-01

    An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

  12. Surface potential of methyl isobutyl carbinol adsorption layer at the air/water interface.

    Science.gov (United States)

    Phan, Chi M; Nakahara, Hiromichi; Shibata, Osamu; Moroi, Yoshikiyo; Le, Thu N; Ang, Ha M

    2012-01-26

    The surface potential (ΔV) and surface tension (γ) of MIBC (methyl isobutyl carbinol) were measured on the subphase of pure water and electrolyte solutions (NaCl at 0.02 and 2 M). In contrast to ionic surfactants, it was found that surface potential gradually increased with MIBC concentration. The ΔV curves were strongly influenced by the presence of NaCl. The available model in literature, in which surface potential is linearly proportional to surface excess, failed to describe the experimental data. Consequently, a new model, employing a partial charge of alcohol adsorption layer, was proposed. The new model predicted the experimental data consistently for MIBC in different NaCl solutions. However, the model required additional information for ionic impurity to predict adsorption in the absence of electrolyte. Such inclusion of impurities is, however, unnecessary for industrial applications. The modeling results successfully quantify the influence of electrolytes on surface potential of MIBC, which is critical for froth stability.

  13. Bone-like apatite coating on functionalized poly(etheretherketone) surface via tailored silanization layers technique.

    Science.gov (United States)

    Zheng, Yanyan; Xiong, Chengdong; Zhang, Shenglan; Li, Xiaoyu; Zhang, Lifang

    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, -PO4H2, -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. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. In situ measurement of fixed charge evolution at silicon surfaces during atomic layer deposition

    International Nuclear Information System (INIS)

    Ju, Ling; Watt, Morgan R.; Strandwitz, Nicholas C.

    2015-01-01

    Interfacial fixed charge or interfacial dipoles are present at many semiconductor-dielectric interfaces and have important effects upon device behavior, yet the chemical origins of these electrostatic phenomena are not fully understood. We report the measurement of changes in Si channel conduction in situ during atomic layer deposition (ALD) of aluminum oxide using trimethylaluminum and water to probe changes in surface electrostatics. Current-voltage data were acquired continually before, during, and after the self-limiting chemical reactions that result in film growth. Our measurements indicated an increase in conductance on p-type samples with p + ohmic contacts and a decrease in conductance on analogous n-type samples. Further, p + contacted samples with n-type channels exhibited an increase in measured current and n + contacted p-type samples exhibited a decrease in current under applied voltage. Device physics simulations, where a fixed surface charge was parameterized on the channel surface, connect the surface charge to changes in current-voltage behavior. The simulations and analogous analytical relationships for near-surface conductance were used to explain the experimental results. Specifically, the changes in current-voltage behavior can be attributed to the formation of a fixed negative charge or the modification of a surface dipole upon chemisorption of trimethylaluminum. These measurements allow for the observation of fixed charge or dipole formation during ALD and provide further insight into the electrostatic behavior at semiconductor-dielectric interfaces during film nucleation

  15. Tribochemical interaction between nanoparticles and surfaces of selective layer during chemical mechanical polishing

    International Nuclear Information System (INIS)

    Ilie, Filip

    2013-01-01

    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

  16. Formation of organic layer on femtosecond laser-induced periodic surface structures

    Energy Technology Data Exchange (ETDEWEB)

    Yasumaru, Naoki, E-mail: yasuma@fukui-nct.ac.jp [National Institute of Technology, Fukui College, Sabae, Fukui 916-8507 (Japan); Sentoku, Eisuke [National Institute of Technology, Fukui College, Sabae, Fukui 916-8507 (Japan); Kiuchi, Junsuke [Eyetec Co., Ltd., Sabae, Fukui 916-0016 (Japan)

    2017-05-31

    Highlights: • Surface analyses of two types of femtosecond laser-induced periodic surface structures (LIPSS) on titanium were conducted. • The parallel-oriented ultrafine LIPSS showed the almost same roughness and chemical states as the non-irradiated Ti surface. • The well-known perpendicular-oriented LIPSS were typically covered with an organic layer similar to a cellulose derivative. - Abstract: Two types of laser-induced periodic surface structures (LIPSS) formed on titanium by femtosecond (fs) laser pulses (λ = 800 nm, τ = 180 fs, ν = 1 kHz) in air were investigated experimentally. At a laser fluence F above the ablation threshold, LIPSS with a minimum mean spacing of D < λ⁄2 were observed perpendicular to the laser polarization direction. In contrast, for F slightly below than the ablation threshold, ultrafine LIPSS with a minimum value of D < λ/10 were formed parallel to the polarization direction. The surface roughness of the parallel-oriented LIPSS was almost the same as that of the non-irradiated surface, unlike the high roughness of the perpendicular-oriented LIPSS. In addition, although the surface state of the parallel-oriented LIPSS was the same as that of the non-irradiated surface, the perpendicular-oriented LIPSS were covered with an organic thin film similar to a cellulose derivative that cannot be easily formed by conventional chemical synthesis. The results of these surface analyses indicate that these two types of LIPSS are formed through different mechanisms. This fs-laser processing technique may become a new technology for the artificial synthesis of cellulose derivatives.

  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. 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)

  20. Creation of oxygen-enriched layers at the surface of GaAs single crystal

    International Nuclear Information System (INIS)

    Kulik, M.; Maczka, D.; Kobzev, A.P.

    1999-01-01

    The optical properties and the element depth profiles at the (100) plane high resistant and noncomposite GaAs single crystals implanted with In ions were investigated. The results have been compared with those obtained for virgin samples. The optic properties for all of the samples (implanted and not implanted, annealed and not annealed) have been measured using the ellipsometric method. The element depth profiles for the same samples have been obtained by the RBS and NRA techniques. It has been shown that the post-implantation annealing at a temperature more than 600 deg C leads to a ten time increase in contents of oxygen atoms in the implanted layer with respect to the not annealed sample. The thickness of the transparence layer at the surface of GaAs single crystal increases also after implantation with In ions and subsequent annealing

  1. 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.

  2. X-ray diffractometric study on the near-surface layer structure in parallel glancing rays

    International Nuclear Information System (INIS)

    Shtypulyak, N.I.; Yakimov, I.I.; Litvintsev, V.V.

    1988-01-01

    X-ray diffraction method is suggested to use to investigate thin films and near-surface layers under the conditions of total external reflection (TER) and in the geometry of parallel glancing rays. Experimental realization of the method using the DRON-30 diffractometer is described. Calculation for the required width of the aperture of Soller slot system is presented. The described diffraction scheme is used to investigate thin film crystal structure at glancing angles in the range from TER up to 8-10 deg. The thickness of the investigated layer in this case changes from 2.5-8 nm up to 10 3 nm. The suggested diffraction method in parallel glancing rays is especially important when investigating the films with thickness lower than 1000-2000A

  3. 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.

  4. Room-temperature vacancy migration in crystalline Si from an ion-implanted surface layer

    DEFF Research Database (Denmark)

    Larsen, Arne Nylandsted; Christensen, Carsten; Petersen, Jon Wulff

    1999-01-01

    Migration of vacancies in crystalline, n-type silicon at room temperature from Ge+-implanted (150 keV, 5×109–1×1011 cm–2) surface layers was studied by tracing the presence of P–V pairs (E centers) in the underlying layer using deep level transient spectroscopy (DLTS). Under the conditions we have......–Et[approximate]0.15 eV that has donor character. It is argued that the center associated with this line is most probably the P2–V complex; it anneals at about 550 K. A lower limit of the RT-diffusion coefficient of the doubly charged, negative vacancy is estimated to be 4×10–11 cm2/s. ©1999 American Institute...

  5. Cooling rate and microstructure of surface layers of 5KhNM steel, machined by electroerosion method

    International Nuclear Information System (INIS)

    Foteev, N.K.; Ploshkin, V.V.; Lyakishev, V.A.; Shirokov, S.V.

    1982-01-01

    The cooling rate and microstructure of surface layers of steel 5KhNM machined by electroerosion method have been studied. It is shown that the difference in heating rate of the surface layers with electric discharge over the 5KhNM steel samples depth results in the intensive size reduction of the microstructure. In the surface layer alongside with martensite residual austenite is present, the lattice period of which increases with the increase of pulse duration, carbide phase of complex composition appears, and concentrational heterogeneity in alloying elements (except carbon) is absent

  6. Cooling rate and microstructure of surface layers of 5KhNM steel, machined by electroerosion method

    Energy Technology Data Exchange (ETDEWEB)

    Foteev, N.K.; Ploshkin, V.V.; Lyakishev, V.A.; Shirokov, S.V.

    1982-01-01

    The cooling rate and microstructure of surface layers of steel 5KhNM machined by electroerosion method have been studied. It is shown that the difference in heating rate of the surface layers with electric discharge over the 5KhNM steel samples depth results in the intensive size reduction of the microstructure. In the surface layer alongside with martensite residual austenite is present, the lattice period of which increases with the increase of pulse duration, carbide phase of complex composition appears, and concentrational heterogeneity in alloying elements (except carbon) is absent.

  7. Micro-EDXRF surface analyses of a bronze spear head: Lead content in metal and corrosion layers

    International Nuclear Information System (INIS)

    Figueiredo, E.; Valerio, P.; Araujo, M.F.; Senna-Martinez, J.C.

    2007-01-01

    A bronze spear head from Central Portugal dated to Late Bronze Age has been analyzed by non-destructive micro-EDXRF in the metal surface and corrosion layers. The artifact had previously been analyzed using a conventional EDXRF spectrometer having a larger incident beam. The quantification of the micro-EDXRF analyses showed that lead content in corrosion layers can reach values up to four times higher than the content determined in the metal surface. Results obtained with the higher energy incident beam from the EDXRF equipment, although referring mainly to the corrosion layers, seem to suffer some influence from the surface composition of the metallic alloy

  8. Deposition of thin layer (monoatomic layer) of barium on gold single crystal surfaces and studies of its oxidation employing X-ray photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Ahmad, H.; Ahmad, R.; Khalid, M.; Alvi, R.A.

    2007-01-01

    Due to the high reactivity of barium with oxygen, some oxygen diffuse into the bulk to form bulk oxide and it is very difficult to differentiate the oxide over layer and the bulk oxide. To study the oxidation of barium surface layer, a thin layer (monolayer) of barium is developed over gold single crystal surface. Gold is selected as support because it is one of the least reactive metal in transition metal group and have very low probability of reaction with oxygen at room temperature (300K). Nitrous oxide (N/sub 2/O) was used as oxidant. Thin layer of barium was deposited on Au(100) surface. The barium coverage on gold surface was calculated that varied from 0.4 to 1.4 monolayer (ML). Photoelectron spectra for O(ls), N(ls), Ba (3d), and Au (4f) have been recorded on X-ray photoelectron spectrometer at different binding energy region specific for each element. The decomposition of nitrous oxide has been observed in all cases. It has found that nitrogen is evolved in the gaseous state and oxygen is adsorbed/chemisorbed on barium over layer. (author)

  9. Surface plasmon resonance investigation of optical detection in plasma-modified phospholipid layers

    International Nuclear Information System (INIS)

    Park, Byoungchoo; Cho, Chanyoun; Choi, Kyoungho; Jeon, Honggoo

    2012-01-01

    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 2 (Ar/O 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 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.

  10. Enhanced Sensitivity of Anti-Symmetrically Structured Surface Plasmon Resonance Sensors with Zinc Oxide Intermediate Layers

    Directory of Open Access Journals (Sweden)

    Nan-Fu Chiu

    2013-12-01

    Full Text Available We report a novel design wherein high-refractive-index zinc oxide (ZnO intermediary layers are used in anti-symmetrically structured surface plasmon resonance (SPR devices to enhance signal quality and improve the full width at half maximum (FWHM of the SPR reflectivity curve. The surface plasmon (SP modes of the ZnO intermediary layer were excited by irradiating both sides of the Au film, thus inducing a high electric field at the Au/ZnO interface. We demonstrated that an improvement in the ZnO (002 crystal orientation led to a decrease in the FWHM of the SPR reflectivity curves. We optimized the design of ZnO thin films using different parameters and performed analytical comparisons of the ZnO with conventional chromium (Cr and indium tin oxide (ITO intermediary layers. The present study is based on application of the Fresnel equation, which provides an explanation and verification for the observed narrow SPR reflectivity curve and optical transmittance spectra exhibited by (ZnO/Au, (Cr/Au, and (ITO/Au devices. On exposure to ethanol, the anti-symmetrically structured showed a huge electric field at the Au/ZnO interface and a 2-fold decrease in the FWHM value and a 1.3-fold larger shift in angle interrogation and a 4.5-fold high-sensitivity shift in intensity interrogation. The anti-symmetrically structured of ZnO intermediate layers exhibited a wider linearity range and much higher sensitivity. It also exhibited a good linear relationship between the incident angle and ethanol concentration in the tested range. Thus, we demonstrated a novel and simple method for fabricating high-sensitivity, high-resolution SPR biosensors that provide high accuracy and precision over relevant ranges of analyte measurement.

  11. 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.

  12. 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.

  13. Effects of a Chitosan Coating Layer on the Surface Properties and Barrier Properties of Kraft Paper

    Directory of Open Access Journals (Sweden)

    Shanhui Wang

    2016-01-01

    Full Text Available Biodegradable chitosan can be applied as a coating on the surface of kraft paper in order to improve its barrier properties against water vapor and air. The food packaging industry can benefit from the addition of chitosan to its current packaging, and in turn reduce pollution from plastic packaging plants. This paper discusses the film formation of chitosan, the permeability of paper coated with a chitosan layer, and the influence on the paper’s surface and barrier properties under different process conditions. SEM (scanning electron microscope, AFM (atomic force microscope, ATR-FTIR (Fourier transmission infrared spectroscope with attenuated total reflection, and PDA (penetration dynamics analysis were used to analyze the properties of chitosan’s film formation and permeability. A controlled experiment showed that the chitosan layer was smoother than the surface of the uncoated kraft paper, had better film formation, and that there was no chitosan penetration through the kraft paper. The barrier properties against water vapor were strongest when there was a higher concentration of chitosan solution at the optimum pH, stirring speed, and those with a thicker coating on the kraft paper.

  14. Ge clusters and wetting layers forming from granular films on the Si(001) surface

    International Nuclear Information System (INIS)

    Storozhevykh, M S; Arapkina, L V; Yuryev, V A

    2016-01-01

    The report studies the transformation of a Ge granular film deposited on the Si(001) surface at room temperature into a Ge/Si(001) heterostructure as a result of rapid heating and annealing at 600 °C. As a result of the short-term annealing at 600 °C in conditions of a closed system, the Ge granular film transforms into a usual wetting layer and Ge clusters with multimodal size distribution and Ge oval drops having the highest number density. After the long-term thermal treatment of the Ge film at the same temperature, Ge drops disappear; the large clusters increase their sizes at the expense of the smaller ones. The total density of Ge clusters on the surface drastically decreases. The wetting layer mixed c(4 x 2) + p(2 x 2) reconstruction transforms into a single c(4 x 2) one which is likely to be thermodynamically favoured. Pyramids or domes are not observed on the surface after any annealing. (paper)

  15. 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.

  16. 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

  17. Structure, composition and morphology of bioactive titanate layer on porous titanium surfaces

    Science.gov (United States)

    Li, Jinshan; Wang, Xiaohua; Hu, Rui; Kou, Hongchao

    2014-07-01

    A bioactive coating was produced on pore surfaces of porous titanium samples by an amendatory alkali-heat treatment method. Porous titanium was prepared by powder metallurgy and its porosity and average size were 45% and 135 μm, respectively. Coating morphology, coating structure and phase constituents were examined by SEM, XPS and XRD. It was found that a micro-network structure with sizes of cells, and redundant Ca ion was detected in the titanate layer. The concentration distribution of Ti, O, Ca and Na in the coating showed a compositional gradient from the intermediate layer toward the outer surface. These compositional gradients indicate that the coating bonded to Ti substrate without a distinct interface. After immersion into the SBF solution for 3 days, a bone-like carbonate-hydroxylapatite showing a good biocompatibility was detected on the coating surface. And the redundant Ca advanced the bioactivity of the coating. Thus, the present modification is expected to allow the use of the bioactive porous titanium as artificial bones even under load-bearing conditions.

  18. Recyclable organic solar cells on substrates comprising cellulose nanocrystals (CNC)

    Science.gov (United States)

    Kippelen, Bernard; Fuentes-Hernandez, Canek; Zhou, Yinhua; Moon, Robert; Youngblood, Jeffrey P

    2015-12-01

    Recyclable organic solar cells are disclosed herein. Systems and methods are further disclosed for producing, improving performance, and for recycling the solar cells. In certain example embodiments, the recyclable organic solar cells disclosed herein include: a first electrode; a second electrode; a photoactive layer disposed between the first electrode and the second electrode; an interlayer comprising a Lewis basic oligomer or polymer disposed between the photoactive layer and at least a portion of the first electrode or the second electrode; and a substrate disposed adjacent to the first electrode or the second electrode. The interlayer reduces the work function associated with the first or second electrode. In certain example embodiments, the substrate comprises cellulose nanocrystals that can be recycled. In certain example embodiments, one or more of the first electrode, the photoactive layer, and the second electrode may be applied by a film transfer lamination method.

  19. Effects of black carbon and boundary layer interaction on surface ozone in Nanjing, China

    Science.gov (United States)

    Gao, Jinhui; Zhu, Bin; Xiao, Hui; Kang, Hanqing; Pan, Chen; Wang, Dongdong; Wang, Honglei

    2018-05-01

    As an important solar radiation absorbing aerosol, the effect of black carbon (BC) on surface ozone, via reducing photolysis rate, has been widely discussed by offline model studies. However, BC-boundary layer (BL) interactions also influence surface ozone. Using the online model simulations and process analysis, we demonstrate the significant impact of BC-BL interaction on surface ozone in Nanjing. The absorbing effect of BC heats the air above the BL and suppresses and delays the development of the BL, which eventually leads to a change in surface ozone via a change in the contributions from chemical and physical processes (photochemistry, vertical mixing and advection). For chemical processes, the suppression of the BL leads to large amounts of ozone precursors being confined below the BL which has an increased effect on ozone chemical production and offsets the decrease caused by the reduction of the photolysis rate, thus enhancing ozone chemical formation from 10:00 to 12:00 LT. Furthermore, changes in physical processes, especially the vertical mixing process, show a more significant influence on surface ozone. The weakened turbulence, caused by the suppressed BL, entrains much less ozone aloft down to the surface. Finally, summing-up the changes in the processes, surface ozone reduces before noon and the maximum reduction reaches 16.4 ppb at 12:00 LT. In the afternoon, the changes in chemical process are small which inconspicuously influence surface ozone. However, change in the vertical mixing process still influences surface ozone significantly. Due to the delayed development of the BL, there are obvious ozone gradients around the top of BL. Therefore, high concentrations of ozone aloft can still be entrained down to the surface which offsets the reduction of surface ozone. Comparing the changes in the processes, the change in vertical mixing plays the most important role in impacting surface ozone. Our results highlight the great impacts BC

  20. Effects of black carbon and boundary layer interaction on surface ozone in Nanjing, China

    Directory of Open Access Journals (Sweden)

    J. Gao

    2018-05-01

    Full Text Available As an important solar radiation absorbing aerosol, the effect of black carbon (BC on surface ozone, via reducing photolysis rate, has been widely discussed by offline model studies. However, BC–boundary layer (BL interactions also influence surface ozone. Using the online model simulations and process analysis, we demonstrate the significant impact of BC–BL interaction on surface ozone in Nanjing. The absorbing effect of BC heats the air above the BL and suppresses and delays the development of the BL, which eventually leads to a change in surface ozone via a change in the contributions from chemical and physical processes (photochemistry, vertical mixing and advection. For chemical processes, the suppression of the BL leads to large amounts of ozone precursors being confined below the BL which has an increased effect on ozone chemical production and offsets the decrease caused by the reduction of the photolysis rate, thus enhancing ozone chemical formation from 10:00 to 12:00 LT. Furthermore, changes in physical processes, especially the vertical mixing process, show a more significant influence on surface ozone. The weakened turbulence, caused by the suppressed BL, entrains much less ozone aloft down to the surface. Finally, summing-up the changes in the processes, surface ozone reduces before noon and the maximum reduction reaches 16.4 ppb at 12:00 LT. In the afternoon, the changes in chemical process are small which inconspicuously influence surface ozone. However, change in the vertical mixing process still influences surface ozone significantly. Due to the delayed development of the BL, there are obvious ozone gradients around the top of BL. Therefore, high concentrations of ozone aloft can still be entrained down to the surface which offsets the reduction of surface ozone. Comparing the changes in the processes, the change in vertical mixing plays the most important role in impacting surface ozone. Our results highlight the

  1. Unexpectedly high soil organic carbon stocks under impervious surfaces contributed by urban deep cultural layers

    Science.gov (United States)

    Bae, J.; Ryu, Y.

    2017-12-01

    The expansion of urban artificial structures has altered the spatial distribution of soil organic carbon (SOC) stocks. The majority of the urban soil studies within the land-cover types, however, focused on top soils despite the potential of deep soils to store large amounts of SOC. Here, we investigate vertical distribution of SOC stocks in both impervious surfaces (n = 11) and adjacent green spaces (n = 8) to a depth of 4 m with in an apartment complex area, Seoul, Republic of Korea. We found that more than six times differences in SOC stocks were observed at 0-1 m depth between the impervious surfaces (1.90 kgC m-2) and the green spaces (12.03 kgC m-2), but no significant differences appeared when comparing them at the depth of 0-4 m. We found "cultural layers" with the largest SOC stocks at 1-2 m depth in the impervious surfaces (15.85 kgC m-2) and 2-3 m depths in urban green spaces (12.52 kgC m-2). Thus, the proportions of SOC stocks at the 0-1 m depth to the total of 0-4 m depth were 6.83% in impervious surfaces and 32.15% in urban green spaces, respectively. The 13C and 15N stable isotope data with historical aerial photographs revealed that the cropland which existed before 1978 formed the SOC in the cultural layers. Our results highlight that impervious surface could hold large amount of SOC stock which has been overlooked in urban carbon cycles. We believe this finding will help city planners and policy makers to develop carbon management programs better towards sustainable urban ecosystems.

  2. 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.

  3. CONCENTRATION OF HARMFUL SUBSTANCES REDUCING IN SURFACE LAYER OF ATMOSPHERE AT RHEOSTAT LOCOMOTIVE TESTS

    Directory of Open Access Journals (Sweden)

    E. A. Bondar

    2010-06-01

    Full Text Available It is shown that at present an acceptable way of reducing the concentration of harmful substances in the surface layer of the atmosphere at rheostat tests of locomotives is their dispersion in a large volume of air. Channels, installed above an exhaust pipe of diesel locomotive with a break at the gas flow, work as ejectors. We have solved jointly the equation of aerodynamic characteristics of the ejector device and the equation of diffusion of gases; as a result the calculated dependence for determining the necessary height of ejector device has been obtained.

  4. 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

  5. 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

  6. 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.

  7. Effect of atomic layer deposition coatings on the surface structure of anodic aluminum oxide membranes.

    Science.gov (United States)

    Xiong, Guang; Elam, Jeffrey W; Feng, Hao; Han, Catherine Y; Wang, Hsien-Hau; Iton, Lennox E; Curtiss, Larry A; Pellin, Michael J; Kung, Mayfair; Kung, Harold; Stair, Peter C

    2005-07-28

    Anodic aluminum oxide (AAO) membranes were characterized by UV Raman and FT-IR spectroscopies before and after coating the entire surface (including the interior pore walls) of the AAO membranes by atomic layer deposition (ALD). UV Raman reveals the presence of aluminum oxalate in bulk AAO, both before and after ALD coating with Al2O3, because of acid anion incorporation during the anodization process used to produce AAO membranes. The aluminum oxalate in AAO exhibits remarkable thermal stability, not totally decomposing in air until exposed to a temperature >900 degrees C. ALD was used to cover the surface of AAO with either Al2O3 or TiO2. Uncoated AAO have FT-IR spectra with two separate types of OH stretches that can be assigned to isolated OH groups and hydrogen-bonded surface OH groups, respectively. In contrast, AAO surfaces coated by ALD with Al2O3 display a single, broad band of hydrogen-bonded OH groups. AAO substrates coated with TiO2 show a more complicated behavior. UV Raman results show that very thin TiO2 coatings (1 nm) are not stable upon annealing to 500 degrees C. In contrast, thicker coatings can totally cover the contaminated alumina surface and are stable at temperatures in excess of 500 degrees C.

  8. 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.

  9. Investigation of surface properties and adhesion mechanisms in the combination of different layers, with the aid of surface analysis methods

    International Nuclear Information System (INIS)

    Olschewski, T.

    1991-01-01

    The aim of the investigations was to characterize the surface properties of organic coating materials and inorganic substrates, which are relevant in the context of microstructure technique developments and to obtain information on the adhesion mechanisms present. Two systems were examined which play an important part in micro-technique, i.e.: for the LIGA process and in the development of micro-sensors based on Chem FET's for chemical analysis. For these systems, i.e.: PMMA/TiO 2 and PVC adipate/Si 3 N 4 , adhesion mechanisms were expected, which occur particularly frequently in adhesive combination of polymers with inorganic substrates, i.e.: the mechanical gearing between polymer molecules and substrate structures and a chemical interaction between the boundary layers of the organic top coating and the inorganic substrate. (orig./DG) [de

  10. 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.

  11. The certification of the surface density (kg/m sub 2 ) of BCR CRM 038 ('fly ash from pulverised coal') comprised in methyl cellulose films simulating dust charged filters. BCR 128

    Energy Technology Data Exchange (ETDEWEB)

    Griepink, B; Marchandise, H; Colinet, E; Dams, R

    1988-01-01

    BCR CRM 38 ('Fly Ash') has been embedded in a stable methylcellulose foil of about 10{mu}m thickness. This has been done by making a slurry of fly ash and methylcellulose in water and spiking it with {sup 42}K as a radioactive tracer. The slurry was spread over glass plates and allowed to dry. 'Filters' of uniform size were punched out of the foil. The surface density (e.g. {mu}g/cm{sup 2}) of the fly ash was calculated for each individual 'filter' by comparing the {sup 42}K-activity of the filter with that of the initial suspension. The uncertainties in the so obtained surface density of random and of systematic origin have been estimated. The total relative uncertainty in the surface density of every element certified in BCR 38 is 4-6%. Studies of stability and homogeneity have revealed that this material is well suited for the verification of the results of non-destructive analytical techniques for dust components.

  12. In Situ Evaluation of Density, Viscosity and Thickness of Adsorbed Soft Layers by Combined Surface Acoustic Wave and Surface Plasmon Resonance

    OpenAIRE

    Francis, L.; Friedt, J. -M.; Zhou, C.; Bertrand, P.

    2003-01-01

    We show the theoretical and experimental combination of acoustic and optical methods for the in situ quantitative evaluation of the density, the viscosity and the thickness of soft layers adsorbed on chemically tailored metal surfaces. For the highest sensitivity and an operation in liquids, a Love mode surface acoustic wave (SAW) sensor with a hydrophobized gold coated sensing area is the acoustic method, while surface plasmon resonance (SPR) on the same gold surface as the optical method is...

  13. 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)

  14. 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...

  15. 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

  16. 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

  17. 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.

  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. 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.