Mechanical Properties of Degraded PMR-15 Resin

NASA Technical Reports Server (NTRS)

Tsuji, Luis C.; McManus, Hugh L.; Bowles, Kenneth J.

1998-01-01

Thermo-oxidative aging produces a non-uniform degradation state in PMR-15 resin. A surface layer, usually attributed to oxidative degradation, forms. This surface layer has different properties from the inner material. A set of material tests was designed to separate the properties of the oxidized surface layer from the properties of interior material. Test specimens were aged at 316 C in either air or nitrogen, for durations of up to 800 hours. The thickness of the oxidized surface layer in air aged specimens, and the shrinkage and Coefficient of Thermal Expansion (CTE) of nitrogen aged specimens were measured directly. Four-point-bend tests were performed to determine modulus of both the oxidized surface layer and the interior material. Bimaterial strip specimens consisting of oxidized surface material and unoxidized interior material were constructed and used to determine surface layer shrinkage and CTE. Results confirm that the surface layer and core materials have substantially different properties.

Surface preparation of substances for continuous convective assembly of fine particles

DOEpatents

Rossi, Robert

2003-01-01

A method for producing periodic nanometer-scale arrays of metal or semiconductor junctions on a clean semiconductor substrate surface is provided comprising the steps of: etching the substrate surface to make it hydrophilic, forming, under an inert atmosphere, a crystalline colloid layer on the substrate surface, depositing a metal or semiconductor material through the colloid layer onto the surface of the substrate, and removing the colloid from the substrate surface. The colloid layer is grown on the clean semiconductor surface by withdrawing the semiconductor substrate from a sol of colloid particles.

Microstructure and properties of Ti-Al intermetallic/Al2O3 layers produced on Ti6Al2Mo2Cr titanium alloy by PACVD method

NASA Astrophysics Data System (ADS)

Sitek, R.; Bolek, T.; Mizera, J.

2018-04-01

The paper presents investigation of microstructure and corrosion resistance of the multi-component surface layers built of intermetallic phases of the Ti-Al system and an outer Al2O3 ceramic sub-layer. The layers were produced on a two phase (α + β) Ti6Al2Mo2Cr titanium alloy using the PACVD method with the participation of trimethylaluminum vapors. The layers are characterized by a high surface hardness and good corrosion, better than that of these materials in the starting state. In order to find the correlation between their structure and properties, the layers were subjected to examinations using optical microscopy, X-ray diffraction analysis (XRD), surface analysis by XPS, scanning electron microscopy (SEM), and analyses of the chemical composition (EDS). The properties examined included: the corrosion resistance and the hydrogen absorptiveness. Moreover growth of the Al2O3 ceramic layer and its influence on the residual stress distribution was simulated using finite element method [FEM]. The results showed that the produced layer has amorphous-nano-crystalline structure, improved corrosion resistance and reduces the permeability of hydrogen as compared with the base material of Ti6Al2Mo2Cr -titanium alloy.

Method of bonding silver to glass and mirrors produced according to this method

DOEpatents

Pitts, J.R.; Thomas, T.M.; Czanderna, A.W.

1984-07-31

A method for adhering silver to a glass substrate for producing mirrors includes attaining a silicon enriched substrate surface by reducing the oxygen therein in a vacuum and then vacuum depositing a silver layer onto the silicon enriched surface. The silicon enrichment can be attained by electron beam bombardment, ion beam bombardment, or neutral beam bombardment. It can also be attained by depositing a metal, such as aluminum, on the substrate surface, allowing the metal to oxidize by pulling oxygen from the substrate surface, thereby leaving a silicon enriched surface, and then etching or eroding the metal oxide layer away to expose the silicon enriched surface. Ultraviolet rays can be used to maintain dangling silicon bonds on the enriched surface until covalent bonding with the silver can occur. This disclosure also includes encapsulated mirrors with diffusion layers built therein. One of these mirrors is assembled on a polymer substrate.

Method of bonding silver to glass and mirrors produced according to this method

DOEpatents

Pitts, John R.; Thomas, Terence M.; Czanderna, Alvin W.

1985-01-01

A method for adhering silver to a glass substrate for producing mirrors includes attaining a silicon enriched substrate surface by reducing the oxygen therein in a vacuum and then vacuum depositing a silver layer onto the silicon enriched surface. The silicon enrichment can be attained by electron beam bombardment, ion beam bombardment, or neutral beam bombardment. It can also be attained by depositing a metal, such as aluminum, on the substrate surface, allowing the metal to oxidize by pulling oxygen from the substrate surface, thereby leaving a silicon enriched surface, and then etching or eroding the metal oxide layer away to expose the silicon enriched surface. Ultraviolet rays can be used to maintain dangling silicon bonds on the enriched surface until covalent bonding with the silver can occur. This disclosure also includes encapsulated mirrors with diffusion layers built therein. One of these mirrors is assembled on a polymer substrate.

Sensitivity of High-Resolution Simulations of Hurricane Bob (1991) to Planetary Boundary Layer Parameterizations

NASA Technical Reports Server (NTRS)

Braun, Scott A.; Tao, Wei-Kuo

1999-01-01

The MM5 mesoscale model is used to simulate Hurricane Bob (1991) using grids nested to high resolution (4 km). Tests are conducted to determine the sensitivity of the simulation to the available planetary boundary layer parameterizations, including the bulk-aerodynamic, Blackadar, Medium-RanGe Forecast (MRF) model, and Burk-Thompson boundary-layer schemes. Significant sensitivity is seen, with minimum central pressures varying by up to 17 mb. The Burk-Thompson and bulk-aerodynamic boundary-layer schemes produced the strongest storms while the MRF scheme produced the weakest storm. Precipitation structure of the simulated hurricanes also varied substantially with the boundary layer parameterizations. Diagnostics of boundary-layer variables indicated that the intensity of the simulated hurricanes generally increased as the ratio of the surface exchange coefficients for heat and momentum, C(sub h)/C(sub M), although the manner in which the vertical mixing takes place was also important. Findings specific to the boundary-layer schemes include: 1) the MRF scheme produces mixing that is too deep and causes drying of the lower boundary layer in the inner-core region of the hurricane; 2) the bulk-aerodynamic scheme produces mixing that is probably too shallow, but results in a strong hurricane because of a large value of C(sub h)/C(sub M) (approximately 1.3); 3) the MRF and Blackadar schemes are weak partly because of smaller surface moisture fluxes that result in a reduced value of C(sub h)/C(sub M) (approximately 0.7); 4) the Burk-Thompson scheme produces a strong storm with C(sub h)/C(sub M) approximately 1; and 5) the formulation of the wind-speed dependence of the surface roughness parameter, z(sub 0), is important for getting appropriate values of the surface exchange coefficients in hurricanes based upon current estimates of these parameters.

Speciation and pulmonary effects of acidic SO x formed on the surface of ultrafine zinc oxide aerosols

NASA Astrophysics Data System (ADS)

Amdur, Mary O.; Chen, Lung Chi; Guty, John; Lam, Hua Fuan; Miller, Patricia D.

Ultrafine metal oxides and SO 2 react during coal combustion or smelting operations to form primary emissions coated with an acidic SO x layer. A ZnO-SO 2-H 2O (mixed 500°C) system generates such particles to provide greatly needed information on both quantitative composition of the surface layer and its effects on the lung. Total S on the particles is related to ZnO concentration and is predominantly S VI. As a surface layer, 20 μg m -3 H 2SO 4 decreases pulmonary diffusing capacity in guinea pigs after four daily 3-h exposures and produces bronchial hypersensitivity following a single 1-h exposure. That 200 μg m -3 H 2SO 4 aerosols of equivalent particle size are needed to produce the same degree of bronchial hypersensitivity emphasizes the importance of the surface layer.

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

NASA Astrophysics Data System (ADS)

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.

Surface Brillouin scattering study of the surface excitations in amorphous silicon layers produced by ion bombardment

NASA Astrophysics Data System (ADS)

Zhang, X.; Comins, J. D.; Every, A. G.; Stoddart, P. R.; Pang, W.; Derry, T. E.

1998-11-01

Thin amorphous silicon layers on crystalline silicon substrates have been produced by argon-ion bombardment of (001) silicon surfaces. Thermally induced surface excitations characteristic of this example of a soft-on-hard system have been investigated by surface Brillouin scattering (SBS) as a function of scattering-angle and amorphous-layer thickness. At large scattering angles or for sufficiently large layer thickness, a second peak is present in the SBS spectrum near the low-energy threshold for the continuum of bulk excitations of the system. The measured spectra are analyzed on the basis of surface elastodynamic Green's functions, which successfully simulate their detailed appearance and identify the second peak as either a Sezawa wave (true surface wave) or a pseudo-Sezawa wave (attenuated surface wave) depending on the scattering parameters. The attributes of the pseudo-Sezawa wave are described; these include its asymmetrical line shape and variation in intensity with k∥d (the product of the surface excitation wave vector and the layer thickness), and its emergence as the Sezawa wave from the low-energy side of the Lamb shoulder at a critical value of k∥d. Furthermore, the behavior of a pronounced minimum in the Lamb shoulder near the longitudinal wave threshold observed in the experiments is reported and is found to be in good agreement with the calculated spectra. The elastic constants of the amorphous silicon layer are determined from the velocity dispersion of the Rayleigh surface acoustic wave and the minimum in the Lamb shoulder.

Gigacycle fatigue behavior by ultrasonic nanocrystalline surface modification.

PubMed

Ahn, D G; Amanov, A; Cho, I S; Shin, K S; Pyoun, Y S; Lee, C S; Park, I G

2012-07-01

Nanocrystalline surface layer up to 84 microm in thick is produced on a specimen made of Al6061-T6 alloy by means of surface treatment called ultrasonic nanocrystalline surface modification (UNSM) technique. The refined grain size is produced in the top-layer and it is increased with increasing depth from the top surface. Vickers microhardness measurement for each nanocrystalline surface layer is performed and measurement results showed that the microhardness is increased from 116 HV up to 150 HV, respectively. In this study, fatigue behavior of Al6061-T6 alloy was studied up to 10(7)-10(9) cycles by using a newly developed ultrasonic fatigue testing (UFT) rig. The fatigue results of the UNSM-treated Al6061-T6 alloy specimens were compared with those of the untreated specimens. The microstructure of the untreated and UNSM-treated specimens was characterized by means of scanning electron microscopey (SEM) and transmission electron microscopey (TEM).

Mechanical Properties of Degraded PMR-15 Resin

NASA Technical Reports Server (NTRS)

Tsuji, Luis C.

2000-01-01

Thermo-oxidative aging produces a nonuniform degradation state in PMR-15 resin. A surface layer, usually attributed to oxidative degradation, forms. This surface layer has different properties from the inner material. A set of material tests was designed to separate the properties of the oxidized surface layer from the properties of interior material. Test specimens were aged at 316 C in either air or nitrogen, for durations of up to 800 hr. The thickness of the oxidized surface layer in air aged specimens, and the shrinkage and coefficient of thermal expansion (CTE) of nitrogen aged specimens were measured directly. The nitrogen-aged specimens were assumed to have the same properties as the interior material in the air-aged specimens. Four-point-bend tests were performed to determine modulus of both the oxidized surface layer and the interior material. Bimaterial strip specimens consisting of oxidized surface material and unoxidized interior material were constructed and used to determine surface layer shrinkage and CTE. Results confirm that the surface layer and core materials have substantially different properties.

Methods for producing thin film charge selective transport layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hammond, Scott Ryan; Olson, Dana C.; van Hest, Marinus Franciscus Antonius Maria

Methods for producing thin film charge selective transport layers are provided. In one embodiment, a method for forming a thin film charge selective transport layer comprises: providing a precursor solution comprising a metal containing reactive precursor material dissolved into a complexing solvent; depositing the precursor solution onto a surface of a substrate to form a film; and forming a charge selective transport layer on the substrate by annealing the film.

An organic surface modifier to produce a high work function transparent electrode for high performance polymer solar cells.

PubMed

Choi, Hyosung; Kim, Hak-Beom; Ko, Seo-Jin; Kim, Jin Young; Heeger, Alan J

2015-02-04

Modification of an ITO electrode with small-molecule organic surface modifier, 4-chloro-benzoic acid (CBA), via a simple spin-coating method produces a high-work-function electrode with high transparency and a hydrophobic surface. As an alternative to PEDOT:PSS, CBA modification achieves efficiency enhancement up to 8.5%, which is attributed to enhanced light absorption within the active layer and smooth hole transport from the active layer to the anode. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In Situ Scanning Tunneling Microscopy Topography Changes of Gold (111) in Aqueous Sulfuric Acid Produced by Electrochemical Surface Oxidation and Reduction and Relaxation Phenomena

NASA Astrophysics Data System (ADS)

Pasquale, M. A.; Nieto, F. J. Rodríguez; Arvia, A. J.

The electrochemical formation and reduction of O-layers on gold (111) films in 1 m sulfuric acid under different potentiodynamic routines are investigated utilizing in situ scanning tunneling microscopy. The surface dynamics is interpreted considering the anodic and cathodic reaction pathways recently proposed complemented with concurrent relaxation phenomena occurring after gold (111) lattice mild disruption (one gold atom deep) and moderate disruption (several atoms deep). The dynamics of both oxidized and reduced gold topographies depends on the potentiodynamic routine utilized to form OH/O surface species. The topography resulting from a mild oxidative disruption is dominated by quasi-2D holes and hillocks of the order of 5 nm, involving about 500-600 gold atoms each, and their coalescence. A cooperative turnover process at the O-layer, in which the anion ad-layer and interfacial water play a key role, determines the oxidized surface topography. The reduction of these O-layers results in gold clusters, their features depending on the applied potential routine. A moderate oxidative disruption produces a surface topography of hillocks and holes several gold atoms high and deep, respectively. The subsequent reduction leads to a spinodal gold pattern. Concurrent coalescence appears to be the result of an Ostwald ripening that involves the surface diffusion of both gold atoms and clusters. These processes produce an increase in surface roughness and an incipient gold faceting. The dynamics of different topographies can be qualitatively explained employing the arguments from colloidal science theory. For 1.1 V ≤ E ≅ Epzc weak electrostatic repulsions favor gold atom/cluster coalescence, whereas for E < Epzc the attenuated electrostatic repulsions among gold surfaces stabilize small clusters over the substrate producing string-like patterns.

Haze Production in Pluto's Atmosphere

NASA Astrophysics Data System (ADS)

Summers, M. E.; Gladstone, R.; Stern, A.; Ennico Smith, K.; Greathouse, T.; Hinson, D. P.; Kammer, J.; Linscott, I.; Olkin, C.; Parker, A. H.; Parker, J. W.; Retherford, K. D.; Schindhelm, E.; Singer, K. N.; Steffl, A.; Strobel, D. F.; Tsang, C.; Tyler, G. L.; Versteeg, M. H.; Weaver, H. A., Jr.; Wong, M. L.; Woods, W. W.; Yung, Y. L.; Young, L. A.; Lisse, C. M.; Lavvas, P.; Renaud, J.; Ewell, M.; Jacobs, A. D.

2015-12-01

One of the most visible manifestations of Pluto's atmosphere observed from the New Horizons spacecraft during the flyby in July 2015 was a global haze layer extending to an altitude ~150 km above Pluto's surface. The haze layer exhibits a significant hemispheric asymmetry and what appears to be layered and/or wave like features. Stellar observations since 1989 have suggested the existence of a haze layer in Pluto's lower atmosphere to explain features in occultation light curves. A haze layer is also expected from photochemical models of Pluto's methane atmosphere wherein hydrocarbons and are produced at altitudes above 100 km altitude, mix downwards, and condense at the low atmospheric temperatures near the surface. However, the observed haze layer(s) extends much higher where the atmospheric temperature is too high for condensation. In this paper we will discuss the production and condensation of photochemical products, and evaluate the possibility that nucleation begins in the ionosphere by a mechanism similar to that proposed for the atmosphere of Titan, where electron attachments initiates a sequence of ion-molecular reactions that ultimately produce aerosol "tholins" that settle downward and coat the surface.

Fabrication of ultrathin multilayered superomniphobic nanocoatings by liquid flame spray, atomic layer deposition, and silanization.

PubMed

Sorvali, Miika; Vuori, Leena; Pudas, Marko; Haapanen, Janne; Mahlberg, Riitta; Ronkainen, Helena; Honkanen, Mari; Valden, Mika; Mäkelä, Jyrki M

2018-05-04

Superomniphobic, i.e. liquid-repellent, surfaces have been an interesting area of research during recent years due to their various potential applications. However, producing such surfaces, especially on hard and resilient substrates like stainless steel, still remains challenging. We present a stepwise fabrication process of a multilayered nanocoating on a stainless steel substrate, consisting of a nanoparticle layer, a nanofilm, and a layer of silane molecules. Liquid flame spray was used to deposit a TiO 2 nanoparticle layer as the bottom layer for producing a suitable surface structure. The interstitial Al 2 O 3 nanofilm, fabricated by atomic layer deposition (ALD), stabilized the nanoparticle layer, and the topmost fluorosilane layer lowered the surface energy of the coating for enhanced omniphobicity. The coating was characterized with field emission scanning electron microscopy, focused ion beam scanning electron microscopy, x-ray photoelectron spectroscopy, contact angle (CA) and sliding angle (SA) measurements, and microscratch testing. The widely recognized requirements for superrepellency, i.e. CA > 150° and SA < 10°, were achieved for deioinized water, diiodomethane, and ethylene glycol. The mechanical stability of the coating could be varied by tuning the thickness of the ALD layer at the expense of repellency. To our knowledge, this is the thinnest superomniphobic coating reported so far, with the average thickness of about 70 nm.

Fabrication of ultrathin multilayered superomniphobic nanocoatings by liquid flame spray, atomic layer deposition, and silanization

NASA Astrophysics Data System (ADS)

Sorvali, Miika; Vuori, Leena; Pudas, Marko; Haapanen, Janne; Mahlberg, Riitta; Ronkainen, Helena; Honkanen, Mari; Valden, Mika; Mäkelä, Jyrki M.

2018-05-01

Superomniphobic, i.e. liquid-repellent, surfaces have been an interesting area of research during recent years due to their various potential applications. However, producing such surfaces, especially on hard and resilient substrates like stainless steel, still remains challenging. We present a stepwise fabrication process of a multilayered nanocoating on a stainless steel substrate, consisting of a nanoparticle layer, a nanofilm, and a layer of silane molecules. Liquid flame spray was used to deposit a TiO2 nanoparticle layer as the bottom layer for producing a suitable surface structure. The interstitial Al2O3 nanofilm, fabricated by atomic layer deposition (ALD), stabilized the nanoparticle layer, and the topmost fluorosilane layer lowered the surface energy of the coating for enhanced omniphobicity. The coating was characterized with field emission scanning electron microscopy, focused ion beam scanning electron microscopy, x-ray photoelectron spectroscopy, contact angle (CA) and sliding angle (SA) measurements, and microscratch testing. The widely recognized requirements for superrepellency, i.e. CA > 150° and SA < 10°, were achieved for deioinized water, diiodomethane, and ethylene glycol. The mechanical stability of the coating could be varied by tuning the thickness of the ALD layer at the expense of repellency. To our knowledge, this is the thinnest superomniphobic coating reported so far, with the average thickness of about 70 nm.

Method for producing nanowire-polymer composite electrodes

DOEpatents

Pei, Qibing; Yu, Zhibin

2017-11-21

A method for producing flexible, nanoparticle-polymer composite electrodes is described. Conductive nanoparticles, preferably metal nanowires or nanotubes, are deposited on a smooth surface of a platform to produce a porous conductive layer. A second application of conductive nanoparticles or a mixture of nanoparticles can also be deposited to form a porous conductive layer. The conductive layer is then coated with at least one coating of monomers that is polymerized to form a conductive layer-polymer composite film. Optionally, a protective coating can be applied to the top of the composite film. In one embodiment, the monomer coating includes light transducing particles to reduce the total internal reflection of light through the composite film or pigments that absorb light at one wavelength and re-emit light at a longer wavelength. The resulting composite film has an active side that is smooth with surface height variations of 100 nm or less.

Surface-enhanced Raman medical probes and system for disease diagnosis and drug testing

DOEpatents

Vo-Dinh, T.

1999-01-26

A probe for a surface-enhanced Raman scattering spectrometer includes a member of optically transmissive material for receiving the excitation radiation from a laser and for carrying the radiation emitted from a specimen to a detector. An end of the member for placing against the specimen has a coating that produces surface enhancement of the specimen during Raman scattering spectroscopic analysis. Specifically the coating is formed by a first layer of microparticles on the member and a metal layer over the first layer. The first layer may form a microstructure surface over which a metal layer is applied. Alternatively the coating may be a material containing microparticles of a metal. An optional layer of a material may be applied to the metal layer to concentrate onto the probe compounds of analytical interest onto the probe. 39 figs.

Surface-enhanced raman medical probes and system for disease diagnosis and drug testing

DOEpatents

Vo-Dinh, Tuan

1999-01-01

A probe for a surface-enhanced Raman scattering spectrometer includes a member of optically transmissive material for receiving the excitation radiation from a laser and for carrying the radiation emitted from a specimen to a detector. An end of the member for placing against the specimen has a coating that produces surface enhancement of the specimen during Raman scattering spectroscopic analysis. Specifically the coating is formed by a first layer of microparticles on the member and a metal layer over the first layer. The first layer may form a microstructure surface over which a metal layer is applied. Alternatively the coating may be a material containing microparticles of a metal. An optional layer of a material may be applied to the metal layer to concentrate onto the probe compounds of analytical interest onto the probe.

Friction and Wear Modifiers Using Solvent Partitioning of Hydrophilic Surface-interactive Chemicals Contained in Boundary Layer-targeted Emulsions

NASA Technical Reports Server (NTRS)

Richmond, Robert Chafee (Inventor); Schramm, Jr., Harry F. (Inventor); Defalco, Francis G. (Inventor)

2013-01-01

A wear and/or friction reducing additive for a lubricating fluid in which the additive is a combination of a moderately hydrophilic single-phase compound and an anti-wear and/or anti-friction aqueous salt solution. The aqueous salt solution produces a coating on boundary layer surfaces. The lubricating fluid can be an emulsion-free hydrophobic oil, hydraulic fluid, antifreeze, or water. Preferably, the moderately hydrophilic single-phase compound is sulfonated castor oil and the aqueous salt solution additionally contains boric acid and zinc oxide. The emulsions produced by the aqueous salt solutions, the moderately hydrophilic single-phase compounds, or the combination thereof provide targeted boundary layer organizers that significantly enhance the anti-wear and/or anti-friction properties of the base lubricant by decreasing wear and/or friction of sliding and/or rolling surfaces at boundary layers.

Friction and Wear Modifiers Using Solvent Partitioning of Hydrophilic Surface-Interactive Chemicals Contained in Boundary Layer-Targeted Emulsions

NASA Technical Reports Server (NTRS)

Defalco, Francis G. (Inventor); Richmond, Robert Chaffee (Inventor); Schramm, Jr., Harry F. (Inventor)

2017-01-01

A wear and/or friction reducing additive for a lubricating fluid in which the additive is a combination of a moderately hydrophilic single-phase compound and an anti-wear and/or anti-friction aqueous salt solution. The aqueous salt solution produces a coating on boundary layer surfaces. The lubricating fluid can be an emulsion-free hydrophobic oil, hydraulic fluid, antifreeze, water, or a water-based lubricant. Preferably, the moderately hydrophilic single-phase compound is sulfonated castor oil and the aqueous salt solution additionally contains boric acid and zinc oxide. The emulsions produced by the aqueous salt solutions, the moderately hydrophilic single-phase compounds, or the combination thereof provide targeted boundary layer organizers that significantly enhance the anti-wear and/or anti-friction properties of the base lubricant by decreasing wear and/or friction of sliding and/or rolling surfaces at boundary layers.

Friction and Wear Modifiers Using Solvent Partitioning of Hydrophilic Surface-Interactive Chemicals Contained in Boundary Layer-Targeted Emulsions

NASA Technical Reports Server (NTRS)

Defalco, Francis G. (Inventor); Richmond, Robert Chaffee (Inventor); Schramm, Harry F., Jr. (Inventor)

2016-01-01

A wear and/or friction reducing additive for a lubricating fluid in which the additive is a combination of a moderately hydrophilic single-phase compound and an anti-wear and/or anti-friction aqueous salt solution. The aqueous salt solution produces a coating on boundary layer surfaces. The lubricating fluid can be an emulsion-free hydrophobic oil, hydraulic fluid, antifreeze, or water. Preferably, the moderately hydrophilic single-phase compound is sulfonated castor oil and the aqueous salt solution additionally contains boric acid and zinc oxide. The emulsions produced by the aqueous salt solutions, the moderately hydrophilic single-phase compounds, or the combination thereof provide targeted boundary layer organizers that significantly enhance the anti-wear and/or anti-friction properties of the base lubricant by decreasing wear and/or friction of sliding and/or rolling surfaces at boundary layers.

Optical heat flux gauge

DOEpatents

Noel, Bruce W.; Borella, Henry M.; Cates, Michael R.; Turley, W. Dale; MaCarthur, Charles D.; Cala, Gregory C.

1991-01-01

A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.

Layered devices having surface curvature and method of constructing same

DOEpatents

Woodbury, Richard C.; Perkins, Raymond T.; Thorne, James M.

1989-01-01

A method of treating a substrate having first and second sides with corresponding oppositely facing first and second surfaces, to produce curvature in the first surface. The method includes the steps of removing material, according to a predetermined pattern, from the second side of the substrate, and applying a stress-producing film of material to at least one surface of the substrate to thereby cause the substrate to bend to produce the desired curvature in the first surface.

Microporous structure with layered interstitial surface treatment, and method and apparatus for preparation thereof

NASA Technical Reports Server (NTRS)

Koontz, Steven L. (Inventor)

1994-01-01

A microporous structure with layered interstitial surface treatments, and method and apparatus for preparation thereof is presented. The structure is prepared by sequentially subjecting a uniformly surface-treated structure to atomic oxygen treatment to remove an outer layer of surface treatment to a generally uniform depth, and then surface treating the so exposed layer with another surface treating agent. The atomic oxygen/surface treatment steps may optionally be repeated, each successive time to a lesser depth, to produce a microporous structure having multilayered surface treatments. The apparatus employs at least one side arm from a main atomic oxygen-containing chamber. The side arm has characteristic relaxation times such that a uniform atomic oxygen dose rate is delivered to a specimen positioned transversely in the side arm spaced from the main gas chamber.

Microporous structure with layered interstitial surface treatment, and method and apparatus for preparation thereof

NASA Technical Reports Server (NTRS)

Koontz, Steven L. (Inventor)

1992-01-01

A microporous structure with layered interstitial surface treatments, and the method and apparatus for its preparation are disclosed. The structure is prepared by sequentially subjecting a uniformly surface treated structure to atomic oxygen treatment to remove an outer layer of surface treatment to a generally uniform depth, and then surface treating the so exposed layer with another surface treating agent. The atomic oxygen/surface treatment steps may optionally be repeated, each successive time to a lesser depth, to produce a microporous structure having multilayered surface treatments. The apparatus employs at least one side arm from a main oxygen-containing chamber. The side arm has characteristic relaxation times such that a uniform atomic oxygen dose rate is delivered to a specimen positioned transversely in the side arm spaced from the main gas chamber.

Optical heat flux gauge

DOEpatents

Noel, Bruce W.; Borella, Henry M.; Cates, Michael R.; Turley, W. Dale; MacArthur, Charles D.; Cala, Gregory C.

1991-01-01

A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator wherein each thermographic layer comprises a plurality of respective thermographic phosphors. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.

Differential partition of virulent Aeromonas salmonicida and attenuated derivatives possessing specific cell surface alterations in polymer aqueous-phase systems

NASA Technical Reports Server (NTRS)

Van Alstine, J. M.; Trust, T. J.; Brooks, D. E.

1986-01-01

Two-polymer aqueous-phase systems in which partitioning of biological matter between the phases occurs according to surface properties such as hydrophobicity, charge, and lipid composition are used to compare the surface properties of strains of the fish pathogen Aeromonas salmonicida. The differential ability of strains to produce a surface protein array crucial to their virulence, the A layer, and to produce smooth lipopolysaccharide is found to be important in the partitioning behavior of Aeromonas salmonicida. The presence of the A layer is shown to decrease the surface hydrophilicity of the pathogen, and to increase specifically its surface affinity for fatty acid esters of polyethylene glycol. The method has application to the analysis of surface properties crucial to bacterial virulence, and to the selection of strains and mutants with specific surface characteristics.

Advances in surfaces and osseointegration in implantology. Biomimetic surfaces

PubMed Central

Albertini, Matteo; Fernandez-Yague, Marc; Lázaro, Pedro; Herrero-Climent, Mariano; Bullon, Pedro; Gil, Francisco-Javier

2015-01-01

The present work is a revision of the processes occurring in osseointegration of titanium dental implants according to different types of surfaces -namely, polished surfaces, rough surfaces obtained from subtraction methods, as well as the new hydroxyapatite biomimetic surfaces obtained from thermochemical processes. Hydroxyapatite’s high plasma-projection temperatures have proven to prevent the formation of crystalline apatite on the titanium dental implant, but lead to the formation of amorphous calcium phosphate (i.e., with no crystal structure) instead. This layer produce some osseointegration yet the calcium phosphate layer will eventually dissolve and leave a gap between the bone and the dental implant, thus leading to osseointegration failure due to bacterial colonization. A new surface -recently obtained by thermochemical processes- produces, by crystallization, a layer of apatite with the same mineral content as human bone that is chemically bonded to the titanium surface. Osseointegration speed was tested by means of minipigs, showing bone formation after 3 to 4 weeks, with the security that a dental implant can be loaded. This surface can be an excellent candidate for immediate or early loading procedures. Key words:Dental implants, implants surfaces, osseointegration, biomimetics surfaces. PMID:25662555

Oscillation of Surface PM2.5 Concentration Resulting from an Alternation of Easterly and Southerly Winds in Beijing: Mechanisms and Implications

NASA Astrophysics Data System (ADS)

Sun, Zhaobin; Zhang, Xiaoling; Zhao, Xiujuan; Xia, Xiangao; Miao, Shiguang; Li, Ziming; Cheng, Zhigang; Wen, Wei; Tang, Yixi

2018-04-01

We used simultaneous measurements of surface PM2.5 concentration and vertical profiles of aerosol concentration, temperature, and humidity, together with regional air quality model simulations, to study an episode of aerosol pollution in Beijing from 15 to 19 November 2016. The potential effects of easterly and southerly winds on the surface concentrations and vertical profiles of the PM2.5 pollution were investigated. Favorable easterly winds produced strong upward motion and were able to transport the PM2.5 pollution at the surface to the upper levels of the atmosphere. The amount of surface PM2.5 pollution transported by the easterly winds was determined by the strength and height of the upward motion produced by the easterly winds and the initial height of the upward wind. A greater amount of PM2.5 pollution was transported to upper levels of the atmosphere by upward winds with a lower initial height. The pollutants were diluted by easterly winds from clean ocean air masses. The inversion layer was destroyed by the easterly winds and the surface pollutants and warm air masses were then lifted to the upper levels of the atmosphere, where they re-established a multi-layer inversion. This region of inversion was strengthened by the southerly winds, increasing the severity of pollution. A vortex was produced by southerly winds that led to the convergence of air along the Taihang Mountains. Pollutants were transported from southern-central Hebei Province to Beijing in the boundary layer. Warm advection associated with the southerly winds intensified the inversion produced by the easterly winds and a more stable boundary layer was formed. The layer with high PM2.5 concentration became dee-per with persistent southerly winds of a certain depth. The polluted air masses then rose over the northern Taihang Mountains to the northern mountainous regions of Hebei Province.

Revegetation of Acid Rock Drainage (ARD) Producing Slope Surface Using Phosphate Microencapsulation and Artificial Soil

NASA Astrophysics Data System (ADS)

Kim, Jae Gon

2017-04-01

Oxidation of sulfides produces acid rock drainage (ARD) upon their exposure to oxidation environment by construction and mining activities. The ARD causes the acidification and metal contamination of soil, surface water and groundwater, the damage of plant, the deterioration of landscape and the reduction of slope stability. The revegetation of slope surface is one of commonly adopted strategies to reduce erosion and to increase slope stability. However, the revegetation of the ARD producing slope surface is frequently failed due to its high acidity and toxic metal content. We developed a revegetation method consisting of microencapsualtion and artificial soil in the laboratory. The revegetation method was applied on the ARD producing slope on which the revegetation using soil coverage and seeding was failed and monitored the plant growth for one year. The phosphate solution was applied on sulfide containing rock to form stable Fe-phosphate mineral on the surface of sulfide, which worked as a physical barrier to prevent contacting oxidants such as oxygen and Fe3+ ion to the sulfide surface. After the microencapsulation, two artificial soil layers were constructed. The first layer containing organic matter, dolomite powder and soil was constructed at 2 cm thickness to neutralize the rising acidic capillary water from the subsurface and to remove the dissolved oxygen from the percolating rain water. Finally, the second layer containing seeds, organic matter, nutrients and soil was constructed at 3 cm thickness on the top. After application of the method, the pH of the soil below the artificial soil layer increased and the ARD production from the rock fragments reduced. The plant growth showed an ordinary state while the plant died two month after germination for the previous revegetation trial. No soil erosion occurred from the slope during the one year field test.

Progress in cold roll bonding of metals

PubMed Central

Li, Long; Nagai, Kotobu; Yin, Fuxing

2008-01-01

Layered composite materials have become an increasingly interesting topic in industrial development. Cold roll bonding (CRB), as a solid phase method of bonding same or different metals by rolling at room temperature, has been widely used in manufacturing large layered composite sheets and foils. In this paper, we provide a brief overview of a technology using layered composite materials produced by CRB and discuss the suitability of this technology in the fabrication of layered composite materials. The effects of process parameters on bonding, mainly including process and surface preparation conditions, have been analyzed. Bonding between two sheets can be realized when deformation reduction reaches a threshold value. However, it is essential to remove surface contamination layers to produce a satisfactory bond in CRB. It has been suggested that the degreasing and then scratch brushing of surfaces create a strong bonding between the layers. Bonding mechanisms, in which the film theory is expressed as the major mechanism in CRB, as well as bonding theoretical models, have also been reviewed. It has also been showed that it is easy for bcc structure metals to bond compared with fcc and hcp structure metals. In addition, hardness on bonding same metals plays an important part in CRB. Applications of composites produced by CRB in industrial fields are briefly reviewed and possible developments of CRB in the future are also described. PMID:27877949

Fluoride-dependent formation of mineralized layers in bovine dentin during demineralization in vitro.

PubMed

Damen, J J; Buijs, M J; ten Cate, J M

1998-01-01

Demineralization of dentin in the presence of fluoride produces lesions with a mineralized surface layer which becomes thicker and more mineralized with higher fluoride concentrations whereas the lesion depth is hardly affected. The aim of this study was to investigate the effects of the time of fluoride treatment and the amount of fluoride taken up on the properties of the mineralized layer. Discs of bovine dentin embedded in methylmethacrylate with one surface exposed were demineralized in 50 mM acetic acid, 2.2 mM CaCl2, 2.2 mM KH2PO4, pH 5.0. At the start and/or later during the demineralization period, the specimens were incubated individually for 1 or 2 days in 10 ml of the same demineralization solution supplemented with 0.5, 2.0 or 5.0 ppm fluoride, which was then assessed for changes in calcium and fluoride concentrations. After 2, 5 and 8 days, specimens were sectioned for microradiographic analysis so as to follow development of the lesions and the mineralized layers. The results were the following: While demineralization with fluoride present at the first day led to the formation of a surface layer, fluoride present only at a later day produced a subsurface layer, not at the lesion front but closer to the surface. This layer resulted from (re)precipitation and not from preservation of the original mineral. The 'integrated mineral content' of the surface layer increased linearly with the uptake of fluoride, which resulted in an apparent fluorapatite content of about 20 vol%. The profiles of the surface layers remained unchanged during continued demineralization in the absence of fluoride. It was concluded that in the presence of fluoride mineral loss is reduced as a result of the reprecipitation of dissolved mineral ions as a layer of fluoride-enriched apatite. This layer does not offer protection of underlying dentin against continued demineralization.

Modification of the Atmospheric Boundary Layer by a Small Island: Observations from Nauru

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matthews, Stuart; Hacker, Jorg M.; Cole, Jason N.

2007-03-01

Nauru, a small island in the tropical pacific, generates plumes of clouds that may grow to several hundred km length. This study uses observations to examine the mesoscale disturbance of the marine atmospheric boundary layer by the island that produces these cloud streets. Observations of the surface layer were made from two ships in the vicinity of Nauru and from instruments on the island. The structure of the atmospheric boundary layer over the island was investigated using aircraft flights. Cloud production over Nauru was examined using remote sensing instruments. During the day the island surface layer was warmer than themore » marine surface layer and wind speed was lower than over the ocean. Surface heating forced the growth of a thermal internal boundary layer, above which a street of cumulus clouds formed. The production of clouds resulted in reduced downwelling shortwave irradiance at the island surface. A plume of warm-dry air was observed over the island which extended 15 – 20 km downwind.« less

Fabrication of a nanometer thick nitrogen delta doped layer at the sub-surface region of (100) diamond

NASA Astrophysics Data System (ADS)

Chandran, Maneesh; Michaelson, Shaul; Saguy, Cecile; Hoffman, Alon

2016-11-01

In this letter, we report on the proof of a concept of an innovative delta doping technique to fabricate an ensemble of nitrogen vacancy centers at shallow depths in (100) diamond. A nitrogen delta doped layer with a concentration of ˜1.8 × 1020 cm-3 and a thickness of a few nanometers was produced using this method. Nitrogen delta doping was realized by producing a stable nitrogen terminated (N-terminated) diamond surface using the RF nitridation process and subsequently depositing a thin layer of diamond on the N-terminated diamond surface. The concentration of nitrogen on the N-terminated diamond surface and its stability upon exposure to chemical vapor deposition conditions are determined by x-ray photoelectron spectroscopy analysis. The SIMS profile exhibits a positive concentration gradient of 1.9 nm/decade and a negative gradient of 4.2 nm/decade. The proposed method offers a finer control on the thickness of the delta doped layer than the currently used ion implantation and delta doping techniques.

Development of optical WGM resonators for biosensors

NASA Astrophysics Data System (ADS)

Brice, I.; Pirktina, A.; Ubele, A.; Grundsteins, K.; Atvars, A.; Viter, R.; Alnis, J.

2017-12-01

Whispering Gallery Mode (WGM) resonators are very sensitive to nanoparticles attaching to the surface. We simulate this process using COMSOL Wave Optics module. Our spherical WGM resonators are produced by melting a tip of an optical fiber and we measure optical Q factors in the 105 range. Molecular oxygen lines of the air in the 760 nm region are used as reference markers when looking for the shifts of the WGM resonance lines. We demonstrate WGM microresonator surface coating with a layer of ZnO nanorods as well as with polystyrene microspheres. Coatings produce increased contact surface. Additional layer of antigens/antibodies will be coated to make high-specificity biosensors.

Mitigation of Corrosion on Magnesium Alloy by Predesigned Surface Corrosion

PubMed Central

Zhang, Xuming; Wu, Guosong; Peng, Xiang; Li, Limin; Feng, Hongqing; Gao, Biao; Huo, Kaifu; Chu, Paul K.

2015-01-01

Rapid corrosion of magnesium alloys is undesirable in structural and biomedical applications and a general way to control corrosion is to form a surface barrier layer isolating the bulk materials from the external environment. Herein, based on the insights gained from the anticorrosion behavior of corrosion products, a special way to mitigate aqueous corrosion is described. The concept is based on pre-corrosion by a hydrothermal treatment of Al-enriched Mg alloys in water. A uniform surface composed of an inner compact layer and top Mg-Al layered double hydroxide (LDH) microsheet is produced on a large area using a one-step process and excellent corrosion resistance is achieved in saline solutions. Moreover, inspired by the super-hydrophobic phenomenon in nature such as the lotus leaves effect, the orientation of the top microsheet layer is tailored by adjusting the hydrothermal temperature, time, and pH to produce a water-repellent surface after modification with fluorinated silane. As a result of the trapped air pockets in the microstructure, the super-hydrophobic surface with the Cassie state shows better corrosion resistance in the immersion tests. The results reveal an economical and environmentally friendly means to control and use the pre-corrosion products on magnesium alloys. PMID:26615896

Mitigation of Corrosion on Magnesium Alloy by Predesigned Surface Corrosion.

PubMed

Zhang, Xuming; Wu, Guosong; Peng, Xiang; Li, Limin; Feng, Hongqing; Gao, Biao; Huo, Kaifu; Chu, Paul K

2015-11-30

Rapid corrosion of magnesium alloys is undesirable in structural and biomedical applications and a general way to control corrosion is to form a surface barrier layer isolating the bulk materials from the external environment. Herein, based on the insights gained from the anticorrosion behavior of corrosion products, a special way to mitigate aqueous corrosion is described. The concept is based on pre-corrosion by a hydrothermal treatment of Al-enriched Mg alloys in water. A uniform surface composed of an inner compact layer and top Mg-Al layered double hydroxide (LDH) microsheet is produced on a large area using a one-step process and excellent corrosion resistance is achieved in saline solutions. Moreover, inspired by the super-hydrophobic phenomenon in nature such as the lotus leaves effect, the orientation of the top microsheet layer is tailored by adjusting the hydrothermal temperature, time, and pH to produce a water-repellent surface after modification with fluorinated silane. As a result of the trapped air pockets in the microstructure, the super-hydrophobic surface with the Cassie state shows better corrosion resistance in the immersion tests. The results reveal an economical and environmentally friendly means to control and use the pre-corrosion products on magnesium alloys.

Mitigation of Corrosion on Magnesium Alloy by Predesigned Surface Corrosion

NASA Astrophysics Data System (ADS)

Zhang, Xuming; Wu, Guosong; Peng, Xiang; Li, Limin; Feng, Hongqing; Gao, Biao; Huo, Kaifu; Chu, Paul K.

2015-11-01

Rapid corrosion of magnesium alloys is undesirable in structural and biomedical applications and a general way to control corrosion is to form a surface barrier layer isolating the bulk materials from the external environment. Herein, based on the insights gained from the anticorrosion behavior of corrosion products, a special way to mitigate aqueous corrosion is described. The concept is based on pre-corrosion by a hydrothermal treatment of Al-enriched Mg alloys in water. A uniform surface composed of an inner compact layer and top Mg-Al layered double hydroxide (LDH) microsheet is produced on a large area using a one-step process and excellent corrosion resistance is achieved in saline solutions. Moreover, inspired by the super-hydrophobic phenomenon in nature such as the lotus leaves effect, the orientation of the top microsheet layer is tailored by adjusting the hydrothermal temperature, time, and pH to produce a water-repellent surface after modification with fluorinated silane. As a result of the trapped air pockets in the microstructure, the super-hydrophobic surface with the Cassie state shows better corrosion resistance in the immersion tests. The results reveal an economical and environmentally friendly means to control and use the pre-corrosion products on magnesium alloys.

Optical heat flux gauge

DOEpatents

Noel, B.W.; Borella, H.M.; Cates, M.R.; Turley, W.D.; MacArthur, C.D.; Cala, G.C.

1991-04-09

A heat flux gauge is disclosed comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator, wherein each thermographic layer comprises a plurality of respective thermographic sensors in a juxtaposed relationship with respect to each other. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable. 9 figures.

Optical heat flux gauge

DOEpatents

Noel, Bruce W.; Borella, Henry M.; Cates, Michael R.; Turley, W. Dale; MacArthur, Charles D.; Cala, Gregory C.

1991-01-01

A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator, wherein each thermographic layer comprises a plurality of respective thermographic sensors in a juxtaposed relationship with respect to each other. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.

The threshold effects of Nd and Ho: YAG laser-induced surface modification on demineralization of dentin surfaces.

PubMed

Kinney, J H; Haupt, D L; Balooch, M; White, J M; Bell, W L; Marshall, S J; Marshall, G W

1996-06-01

Laser irradiation alters the structure of dentin and produces surface layers that give the appearance of being more enamel-like. The laser-modified surface may be more resistant to demineralization; hence, many investigators are proposing continued development of the laser as a possible preventive treatment for caries. The purpose of this study was to explore the morphological changes that occur in dentin when treated at threshold illuminance with two clinically interesting laser wavelengths, and to evaluate the effectiveness of the laser-treated surface at resisting demineralization in an acid-gel solution. The Nd: YAG laser (wavelength 1060 nm) produced significant recrystallization and grain growth of the apatite, without the formation of second phases such as beta-tricalcium phosphate. This recrystallized surface layer showed resistance to demineralization; however, the layer did not provide protection of the underlying dentin from demineralization because of cracks and macroscopic voids that allowed for penetration of the demineralizing gel. The Ho: YAG laser-treated surface (wavelength 2100 nm) did not show significant evidence of recrystallization and grain growth, and only a trace amount of an acid-resistant layer was observed with demineralization. It is speculated that the Ho:YAG laser is coupling with absorbed water, and that the heat transfer from the water to the mineral phase is inefficient. For the purposes of creating a demineralization-resistant layer, threshold illuminance with both Nd: YAG and Ho: YAG was ineffective.

Laser surface treatment of porous ceramic substrate for application in solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Mahmod, D. S. A.; Khan, A. A.; Munot, M. A.; Glandut, N.; Labbe, J. C.

2016-08-01

Laser has offered a large number of benefits for surface treatment of ceramics due to possibility of localized heating, very high heating/cooling rates and possibility of growth of structural configurations only produced under non-equilibrium high temperature conditions. The present work investigates oxidation of porous ZrB2-SiC sintered ceramic substrates through treatment by a 1072 ± 10 nm ytterbium fiber laser. A multi-layer structure is hence produced showing successively oxygen rich distinct layers. The porous bulk beneath these layers remained unaffected as this laser-formed oxide scale and protected the substrate from oxidation. A glassy SiO2 structure thus obtained on the surface of the substrate becomes subject of interest for further research, specifically for its utilization as solid protonic conductor in Solid Oxide Fuel Cells (SOFCs).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Polemi, A.; Shuford, K. L.

We investigate the use of a Fabry-Perot dielectric structure combined with differently shaped nanoparticles for Surface Enhanced Raman Scattering. In particular, we show how an ideal two-layer Fabry-Perot configuration enhances the local surface field of silver nanoparticles positioned on the surface of the structure. We develop the concept using disc dimers and then extend the discussion to bowtie nanoparticles. The structure is excited by a single emitter, which couples to the nanoparticles through the dielectric layers, producing a wide aperture field that can be used to excite multiple dimers. We show how an array of nanoparticles can be properly arrangedmore » in order to increase the total scattering signal generated from the structure. The layered geometry produces robust field properties in between nanoparticles, making the overall sensing characteristics less sensitive to the interparticle seperation distance and incident polarization.« less

The salinity effect in a mixed layer ocean model

NASA Technical Reports Server (NTRS)

Miller, J. R.

1976-01-01

A model of the thermally mixed layer in the upper ocean as developed by Kraus and Turner and extended by Denman is further extended to investigate the effects of salinity. In the tropical and subtropical Atlantic Ocean rapid increases in salinity occur at the bottom of a uniformly mixed surface layer. The most significant effects produced by the inclusion of salinity are the reduction of the deepening rate and the corresponding change in the heating characteristics of the mixed layer. If the net surface heating is positive, but small, salinity effects must be included to determine whether the mixed layer temperature will increase or decrease. Precipitation over tropical oceans leads to the development of a shallow stable layer accompanied by a decrease in the temperature and salinity at the sea surface.

Influence of the foundation layer on the layer-by-layer assembly of poly-L-lysine and poly(styrenesulfonate) and its usage in the fabrication of 3D microscale features.

PubMed

Zhou, Dejian; Bruckbauer, Andreas; Batchelor, Matthew; Kang, Dae-Joon; Abell, Chris; Klenerman, David

2004-10-12

The layer-by-layer (LBL) assembly of a polypeptide, poly-L-lysine (PLL), with poly(styrenesulfonate) sodium salt (PSS) on flat template-stripped gold (TSG) surfaces precoated with a self-assembled monolayer of alkanethiols terminated with positive (pyridinium), negative (carboxylic acid), and neutral [hexa(ethylene glycol)] groups is investigated. Both the topography and the rate of film thickness growth are found to be strongly dependent on the initial surface foundation layer. LBL assembly of PLL and PSS on patterned TSG surfaces produced by micro contact printing leads to structurally distinct microscale features, including pillars, ridges, and wells, whose height can be controlled with nanometer precision. Copyright 2004 American Chemical Society

Microparticle impact sensor measures energy directly

NASA Technical Reports Server (NTRS)

Alexander, W. M.; Berg, O. E.

1965-01-01

Construction of a capacitor sensor consisting of a dielectric layer between two conductive surface layers and connected across a potential source through a sensing resistor permits measurement of energy of impinging particles without degradation of sensitivity. A measurable response is produced without penetration of the dielectric layer.

Secondary treatment of films of colloidal quantum dots for optoelectronics and devices produced thereby

DOEpatents

Semonin, Octavi Escala; Luther, Joseph M; Beard, Matthew C; Chen, Hsiang-Yu

2014-04-01

A method of forming an optoelectronic device. The method includes providing a deposition surface and contacting the deposition surface with a ligand exchange chemical and contacting the deposition surface with a quantum dot (QD) colloid. This initial process is repeated over one or more cycles to form an initial QD film on the deposition surface. The method further includes subsequently contacting the QD film with a secondary treatment chemical and optionally contacting the surface with additional QDs to form an enhanced QD layer exhibiting multiple exciton generation (MEG) upon absorption of high energy photons by the QD active layer. Devices having an enhanced QD active layer as described above are also disclosed.

Method for producing hydrophobic aerogels

DOEpatents

Hrubesh, Lawrence W.; Poco, John F.; Coronado, Paul R.

1999-01-01

A method for treating a dried monolithic aerogel containing non-dispersed particles, with an organometallic surface modifying agent to produce hydrophobic aerogels. The dried, porous hydrophobic aerogels contain a protective layer of alkyl groups, such as methyl groups, on the modified surfaces of the pores of the aerogel. The alkyl groups at the aerogel surface typically contain at least one carbon-metal bond per group.

Receptivity of the Boundary Layer to Vibrations of the Wing Surface

NASA Astrophysics Data System (ADS)

Bernots, Tomass; Ruban, Anatoly; Pryce, David; Laminar Flow Control UK Group Team

2014-11-01

In this work we study generation of Tollmien-Schlichting (T-S) waves in the boundary layer due to elastic vibrations of the wing surface. The flow is investigated based on the asymptotic analysis of the Navier-Stokes equations at large values of the Reynolds number. It is assumed that in the spectrum of the wing vibrations there is a harmonic which comes in resonance with the T-S wave on the lower branch of the stability curve. It was found that the vibrations of the wing surface produce pressure perturbations in the flow outside the boundary layer which can be calculated with the help of the piston theory. As the pressure perturbations penetrate into the boundary layer, a Stokes layer forms on the wing surface which appears to be influenced significantly by the compressibility of the flow, and is incapable of producing the T-S waves. The situation changes when the Stokes layer encounters an roughness; near which the flow is described using the triple-deck theory. The solution of the triple-deck problem can be found in an analytic form. Our main concern is with the flow behaviour downstream of the roughness and, in particular, with the amplitude of the generated Tollmien-Schlichting waves. This research was performed in the Laminar Flow Control Centre (LFC-UK) at Imperial College London. The centre is supported by EPSRC, Airbus UK and EADS Innovation Works.

The effect of surface nanocrystallization on plasma nitriding behaviour of AISI 4140 steel

NASA Astrophysics Data System (ADS)

Li, Yang; Wang, Liang; Zhang, Dandan; Shen, Lie

2010-11-01

A plastic deformation surface layer with nanocrystalline grains was produced on AISI 4140 steel by means of surface mechanical attrition treatment (SMAT). Plasma nitriding of SMAT and un-SMAT AISI 4140 steel was carried out by a low-frequency pulse excited plasma unit. A series of nitriding experiments has been conducted at temperatures ranging from 380 to 500 °C for 8 h in an NH 3 gas. The samples were characterized using X-ray diffraction, scanning electron microscopy, optical microscopy and Vickers microhardness tester. The results showed that a much thicker compound layer with higher hardness was obtained for the SMAT samples when compared with un-SMAT samples after nitriding at the low temperature. In particular, plasma nitriding SMAT AISI 4140 steel at 380 °C for 8 h can produced a compound layer of 2.5 μm thickness with very high hardness on the surface, which is similar to un-SMAT samples were plasma nitrided at approximately 430 °C within the same time.

Origin of the outer layer of martian low-aspect ratio layered ejecta craters

NASA Astrophysics Data System (ADS)

Boyce, Joseph M.; Wilson, Lionel; Barlow, Nadine G.

2015-01-01

Low-aspect ratio layered ejecta (LARLE) craters are one of the most enigmatic types of martian layered ejecta craters. We propose that the extensive outer layer of these craters is produced through the same base surge mechanism as that which produced the base surge deposits generated by near-surface, buried nuclear and high-explosive detonations. However, the LARLE layers have higher aspect ratios compared with base surge deposits from explosion craters, a result of differences in thicknesses of these layers. This characteristics is probably caused by the addition of large amounts of small particles of dust and ice derived from climate-related mantles of snow, ice and dust in the areas where LARLE craters form. These deposits are likely to be quickly stabilized (order of a few days to a few years) from eolian erosion by formation of duricrust produced by diffusion of water vapor out of the deposits.

Microstructure, phase composition and corrosion resistance of Ni2O3 coatings produced using laser alloying method

NASA Astrophysics Data System (ADS)

Bartkowska, Aneta; Przestacki, Damian; Chwalczuk, Tadeusz

2016-12-01

The paper presents the studies' results of microstructure, microhardness, cohesion, phase composition and the corrosion resistance analysis of C45 steel after laser alloying with nickel oxide (Ni2O3). The aim of the laser alloying was to obtain the surface layer with new properties through covering C45 steel by precoat containing modifying compound, and then remelting this precoat using laser beam. As a result of this process the surface layer consisting of remelted zone and heat affected zone was obtained. In the remelted zone an increased amount of modifying elements was observed. It was also found that the surface layer formed during the laser alloying with Ni2O3 was characterized by good corrosion resistance. This property has changed depending on the thickness of the applied precoat. It was observed that the thickness increase of nickel oxides precoat improves corrosion resistance of produced coatings.

Sensing Properties of a Fabry-Perot Dielectric Structure and Dimer Nanoparticles

DOE PAGES

Polemi, A.; Shuford, K. L.

2012-01-01

We investigate the use of a Fabry-Perot dielectric structure combined with differently shaped nanoparticles for Surface Enhanced Raman Scattering. In particular, we show how an ideal two-layer Fabry-Perot configuration enhances the local surface field of silver nanoparticles positioned on the surface of the structure. We develop the concept using disc dimers and then extend the discussion to bowtie nanoparticles. The structure is excited by a single emitter, which couples to the nanoparticles through the dielectric layers, producing a wide aperture field that can be used to excite multiple dimers. We show how an array of nanoparticles can be properly arrangedmore » in order to increase the total scattering signal generated from the structure. The layered geometry produces robust field properties in between nanoparticles, making the overall sensing characteristics less sensitive to the interparticle seperation distance and incident polarization.« less

Direct metal brazing to cermet feedthroughs

DOEpatents

Not Available

1982-07-29

An improved method for brazing metallic components to a cermet surface in an alumina substrate eliminates the prior art metallized layer over the cermet via and adjoining alumina surfaces. Instead, a nickel layer is applied over the cermet surface only and metallic components are brazed directly to this nickel coated cermet surface. As a result, heretofore unachievable tensile strength joints are produced. In addition, cermet vias with their brazed metal components can be spaced more closely in the alumina substrate because of the elimination of the prior art metallized alumina surfaces.

Direct metal brazing to cermet feedthroughs

DOEpatents

Hopper, Jr., Albert C.

1984-12-18

An improved method for brazing metallic components to a cermet surface in an alumina substrate eliminates the prior art metallized layer over the cermet via and adjoining alumina surfaces. Instead, a nickel layer is applied over the cermet surface only and metallic components are brazed directly to this nickel coated cermet surface. As a result, heretofore unachievable tensile strength joints are produced. In addition, cermet vias with their brazed metal components can be spaced more closely in the alumina substrate because of the elimination of the prior art metallized alumina surfaces.

Ablative Laser Propulsion Using Multi-Layered Material Systems

NASA Technical Reports Server (NTRS)

Nehls, Mary; Edwards, David; Gray, Perry; Schneider, T.

2002-01-01

Experimental investigations are ongoing to study the force imparted to materials when subjected to laser ablation. When a laser pulse of sufficient energy density impacts a material, a small amount of the material is ablated. A torsion balance is used to measure the momentum produced by the ablation process. The balance consists of a thin metal wire with a rotating pendulum suspended in the middle. The wire is fixed at both ends. Recently, multi-layered material systems were investigated. These multi-layered materials were composed of a transparent front surface and opaque sub surface. The laser pulse penetrates the transparent outer surface with minimum photon loss and vaporizes the underlying opaque layer.

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

NASA Astrophysics Data System (ADS)

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.

Processing and mechanical characterization of alumina laminates

NASA Astrophysics Data System (ADS)

Montgomery, John K.

2002-08-01

Single-phase ceramics that combine property gradients or steps in monolithic bodies are sought as alternatives to ceramic composites made of dissimilar materials. This work describes novel processing methods to produce stepped-density (or laminated) alumina single-phase bodies that maintain their mechanical integrity. One arrangement consists of a stiff, dense bulk material with a thin, flaw tolerant, porous exterior layer. Another configuration consists of a lightweight, low-density bulk material with a thin, hard, wear resistant exterior layer. Alumina laminates with strong interfaces have been successfully produced in this work using two different direct-casting processes. Gelcasting is a useful near-net shape processing technique that has been combined with several techniques, such as reaction bonding of aluminum oxide and the use of starch as a fugative filler, to successfully produced stepped-density alumina laminates. The other direct casting process that has been developed in this work is thermoreversible gelcasting (TRG). This is a reversible gelation process that has been used to produce near-net shape dense ceramic bodies. Also, individual layers can be stacked together and heated to produce laminates. Bilayer laminate samples were produced with varied thickness of porous and dense layers. It was shown that due to the difference in modulus and hardness, transverse cracking is found upon Hertzian contact when the dense layer is on the exterior. In the opposite arrangement, compacted damage zones formed in the porous material and no damage occurred in the underlying dense layer. Flaw tolerant behavior of the porous exterior/dense underlayer was examined by measuring biaxial strength as a function of Vickers indentation load. It was found that the thinnest layer of porous material results in the greatest flaw tolerance. Also, higher strength was exhibited at large indentation loads when compared to dense monoliths. The calculated stresses on the surfaces and interface afforded an explanation of the behavior that failure initiates at the interface between the layers for the thinnest configuration, rather than the sample surface.

High efficiency, low cost, thin film silicon solar cell design and method for making

DOEpatents

Sopori, Bhushan L.

2001-01-01

A semiconductor device having a substrate, a conductive intermediate layer deposited onto said substrate, wherein the intermediate layer serves as a back electrode, an optical reflector, and an interface for impurity gettering, and a semiconductor layer deposited onto said intermediate layer, wherein the semiconductor layer has a grain size at least as large as the layer thickness, and preferably about ten times the layer thickness. The device is formed by depositing a metal layer on a substrate, depositing a semiconductive material on the metal-coated substrate to produce a composite structure, and then optically processing the composite structure by illuminating it with infrared electromagnetic radiation according to a unique time-energy profile that first produces pits in the backside surface of the semiconductor material, then produces a thin, highly reflective, low resistivity alloy layer over the entire area of the interface between the semiconductor material and the metal layer, and finally produces a grain-enhanced semiconductor layer. The time-energy profile includes increasing the energy to a first energy level to initiate pit formation and create the desired pit size and density, then ramping up to a second energy level in which the entire device is heated to produce an interfacial melt, and finally reducing the energy to a third energy level and holding for a period of time to allow enhancement in the grain size of the semiconductor layer.

High efficiency low cost thin film silicon solar cell design and method for making

DOEpatents

Sopori, Bhushan L.

1999-01-01

A semiconductor device having a substrate, a conductive intermediate layer deposited onto said substrate, wherein the intermediate layer serves as a back electrode, an optical reflector, and an interface for impurity gettering, and a semiconductor layer deposited onto said intermediate layer, wherein the semiconductor layer has a grain size at least as large as the layer thickness, and preferably about ten times the layer thickness. The device is formed by depositing a metal layer on a substrate, depositing a semiconductive material on the metal-coated substrate to produce a composite structure, and then optically processing the composite structure by illuminating it with infrared electromagnetic radiation according to a unique time-energy profile that first produces pits in the backside surface of the semiconductor material, then produces a thin, highly reflective, low resistivity alloy layer over the entire area of the interface between the semiconductor material and the metal layer, and finally produces a grain-enhanced semiconductor layer. The time-energy profile includes increasing the energy to a first energy level to initiate pit formation and create the desired pit size and density, then ramping up to a second energy level in which the entire device is heated to produce an interfacial melt, and finally reducing the energy to a third energy level and holding for a period of time to allow enhancement in the grain size of the semiconductor layer.

Condensing Heat Exchanger with Hydrophilic Antimicrobial Coating

NASA Technical Reports Server (NTRS)

Thomas, Christopher M. (Inventor); Ma, Yonghui (Inventor)

2014-01-01

A multi-layer antimicrobial hydrophilic coating is applied to a substrate of anodized aluminum, although other materials may form the substrate. A silver layer is sputtered onto a thoroughly clean anodized surface of the aluminum to about 400 nm thickness. A layer of crosslinked, silicon-based macromolecular structure about 10 nm thickness overlies the silver layer, and the outermost surface of the layer of crosslinked, silicon-based macromolecular structure is hydroxide terminated to produce a hydrophilic surface with a water drop contact angle of less than 10.degree.. The coated substrate may be one of multiple fins in a condensing heat exchanger for use in the microgravity of space, which has narrow channels defined between angled fins such that the surface tension of condensed water moves water by capillary flow to a central location where it is pumped to storage. The antimicrobial coating prevents obstruction of the capillary passages.

Cryogenic target formation using cold gas jets

DOEpatents

Hendricks, Charles D.

1981-01-01

A method and apparatus using cold gas jets for producing a substantially uniform layer of cryogenic materials on the inner surface of hollow spherical members having one or more layers, such as inertially imploded targets. By vaporizing and quickly refreezing cryogenic materials contained within a hollow spherical member, a uniform layer of the materials is formed on an inner surface of the spherical member. Basically the method involves directing cold gas jets onto a spherical member having one or more layers or shells and containing the cryogenic material, such as a deuterium-tritium (DT) mixture, to freeze the contained material, momentarily heating the spherical member so as to vaporize the contained material, and quickly refreezing the thus vaporized material forming a uniform layer of cryogenic material on an inner surface of the spherical member.

Cryogenic target formation using cold gas jets

DOEpatents

Hendricks, Charles D. [Livermore, CA

1980-02-26

A method and apparatus using cold gas jets for producing a substantially uniform layer of cryogenic materials on the inner surface of hollow spherical members having one or more layers, such as inertially imploded targets. By vaporizing and quickly refreezing cryogenic materials contained within a hollow spherical member, a uniform layer of the materials is formed on an inner surface of the spherical member. Basically the method involves directing cold gas jets onto a spherical member having one or more layers or shells and containing the cryogenic material, such as a deuterium-tritium (DT) mixture, to freeze the contained material, momentarily heating the spherical member so as to vaporize the contained material, and quickly refreezing the thus vaporized material forming a uniform layer of cryogenic material on an inner surface of the spherical member.

A Coupled Model of Langmuir Circulations and Ramp-like Structures in the Upper Ocean Turbulent Boundary Layer

NASA Astrophysics Data System (ADS)

Soloviev, A.; Dean, C.; Lukas, R.; Donelan, M. A.; Terray, E. A.

2016-12-01

Surface-wave breaking is a powerful mechanism producing significant energy flux to small scale turbulence. Most of the turbulent energy produced by breaking waves dissipates within one significant wave height, while the turbulent diffusion layer extends to approximately ten significant wave heights. Notably, the near-surface shear may practically vanish within the wave-stirred layer due to small-scale turbulent mixing. The surface ocean temperature-salinity structure, circulation, and mass exchanges (including greenhouse gases and pollutants) substantially depend on turbulent mixing and non-local transport in the near-surface layer of the ocean. Spatially coherent organized motions have been recognized as an important part of non-local transport. Langmuir circulation (LC) and ramp-like structures are believed to vertically transfer an appreciable portion of the momentum, heat, gases, pollutants (e.g., oil), and other substances in the upper layer of the ocean. Free surface significantly complicates the analysis of turbulent exchanges at the air-sea interface and the coherent structures are not yet completely understood. In particular, there is growing observational evidence that in the case of developing seas when the wind direction may not coincide with the direction of the energy containing waves, the Langmuir lines are oriented in the wind rather than the wave direction. In addition, the vortex force due to Stokes drift in traditional models is altered in the breaking-wave-stirred layer. Another complication is that the ramp-like structures in the upper ocean turbulent boundary layer have axes perpendicular to the axes of LC. The ramp-like structures are not considered in the traditional model. We have developed a new model, which treats the LC and ramp-like structures in the near-surface layer of the ocean as a coupled system. Using computational fluid dynamics tools (LES), we have been able to reproduce both LC and ramp-like structures coexisting in space though intermittent in time. In the model, helicity isosurfaces appear to be tilted and, in general, coordinated with the tilted velocity isosurfaces produced by ramp-like structures. This is an indication of coupling between the LC and ramp-like structures. Remarkably, the new model is able to explain observations of LC under developing seas.

Use of screenings to produce HMA mixtures

DOT National Transportation Integrated Search

2002-10-01

Thin-lift hot mix asphalt (HMA) layers are utilized in almost every maintenance and rehabilitation application. These mix types require smaller maximum particle sizes than most conventional HMA surface layers. Although the primary functions of thin-l...

Mean flow field and surface heating produced by unequal shock interactions at hypersonic speeds

NASA Technical Reports Server (NTRS)

Birch, S. F.; Rudy, D. H.

1975-01-01

Mean velocity profiles were measured in a free shear layer produced by the interaction of two unequal strength shock waves at hypersonic free-stream Mach numbers. Measurements were made over a unit Reynolds number range of 3,770,000 per meter to 17,400,000 per meter based on the flow on the high velocity side of the shear layer. The variation in measured spreading parameters with Mach number for the fully developed flows is consistent with the trend of the available zero velocity ratio data when the Mach numbers for the data given in this study are taken to be characteristic Mach numbers based on the velocity difference across the mixing layer. Surface measurements in the shear-layer attachment region of the blunt-body model indicate peak local heating and static pressure consistent with other published data. Transition Reynolds numbers were found to be significantly lower than those found in previous data.

Uranium passivation by C + implantation: A photoemission and secondary ion mass spectrometry study

NASA Astrophysics Data System (ADS)

Nelson, A. J.; Felter, T. E.; Wu, K. J.; Evans, C.; Ferreira, J. L.; Siekhaus, W. J.; McLean, W.

2006-03-01

Implantation of 33 keV C + ions into polycrystalline U 238 with a dose of 4.3 × 10 17 cm -2 produces a physically and chemically modified surface layer that prevents further air oxidation and corrosion. X-ray photoelectron spectroscopy and secondary ion mass spectrometry were used to investigate the surface chemistry and electronic structure of this C + ion implanted polycrystalline uranium and a non-implanted region of the sample, both regions exposed to air for more than a year. In addition, scanning electron microscopy was used to examine and compare the surface morphology of the two regions. The U 4f, O 1s and C 1s core-level and valence band spectra clearly indicate carbide formation in the modified surface layer. The time-of-flight secondary ion mass spectrometry depth profiling results reveal an oxy-carbide surface layer over an approximately 200 nm thick UC layer with little or no residual oxidation at the carbide layer/U metal transitional interface.

Modification of Low-Alloy Steel Surface by High-Temperature Gas Nitriding Plus Tempering

NASA Astrophysics Data System (ADS)

Jiao, Dongling; Li, Minsong; Ding, Hongzhen; Qiu, Wanqi; Luo, Chengping

2018-02-01

The low-alloy steel was nitrided in a pure NH3 gas atmosphere at 640 660 °C for 2 h, i.e., high-temperature gas nitriding (HTGN), followed by tempering at 225 °C, which can produce a high property surface coating without brittle compound (white) layer. The steel was also plasma nitriding for comparison. The composition, microstructure and microhardness of the nitrided and tempered specimens were examined, and their tribological behavior investigated. The results showed that the as-gas-nitrided layer consisted of a white layer composed of FeN0.095 phase (nitrided austenite) and a diffusional zone underneath the white layer. After tempering, the white layer was decomposed to a nano-sized (α-Fe + γ'-Fe4N + retained austenite) bainitic microstructure with a high hardness of 1150HV/25 g. Wear test results showed that the wear resistance and wear coefficient yielded by the complex HTGN plus tempering were considerably higher and lower, respectively, than those produced by the conventional plasma nitriding.

Metalorganic deposition method for forming epitaxial thallium-based copper oxide superconducting films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olsen, W.L.; Eddy, M.M.; Hammond, R.B.

1991-12-10

This patent describes a method for producing a superconducting article comprising an oriented metal oxide superconducting layer containing thallium, optionally calcium, barium and copper, the layer being at least 30 {Angstrom} and having a c-axis oriented normal to a crystalline substrate surface. It comprises coating the crystalline substrate surface with a solution of thallium, optionally calcium, barium and copper carboxylate soaps dispersed in a medium of hydrocarbons of halohydrocarbons with a stoichiometric metal ratio to form the oxide superconducting layer, prepyrolyzing the soaps coated on the substrate at a temperature of 350{degrees} C. or less in an oxygen containing atmosphere,more » and pyrolyzing the soaps at a temperature in the range of 800{degrees} - 900{degrees} C. in the presence of oxygen and an overpressure of thallium for a sufficient time to produce the superconducting layer on the substrate, wherein usable portions of the superconducting layer are epitaxial to the substrate.« less

Closing the Seasonal Ocean Surface Temperature Balance in the Eastern Tropical Oceans from Remote Sensing and Model Reanalyses

NASA Technical Reports Server (NTRS)

Roberts, J. Brent; Clayson, C. A.

2012-01-01

Residual forcing necessary to close the MLTB on seasonal time scales are largest in regions of strongest surface heat flux forcing. Identifying the dominant source of error - surface heat flux error, mixed layer depth estimation, ocean dynamical forcing - remains a challenge in the eastern tropical oceans where ocean processes are very active. Improved sub-surface observations are necessary to better constrain errors. 1. Mixed layer depth evolution is critical to the seasonal evolution of mixed layer temperatures. It determines the inertia of the mixed layer, and scales the sensitivity of the MLTB to errors in surface heat flux and ocean dynamical forcing. This role produces timing impacts for errors in SST prediction. 2. Errors in the MLTB are larger than the historical 10Wm-2 target accuracy. In some regions, a larger accuracy can be tolerated if the goal is to resolve the seasonal SST cycle.

Influence of substrate material and surface finishing on the morphology of the calcium-phosphate coating.

PubMed

Leitão, E; Barbosa, M A; de Groot, K

1997-07-01

The formation of an apatite-like layer was achieved by immersing Ti-6A1-4V, Ti-Al-2.5Fe, and 316 L stainless-steel substrata in Hank's balanced salt solution (HBSS). The layer was characterized by surface analysis techniques, namely X-ray microanalysis and X-ray diffraction, and the morphology was observed by scanning electron microscopy and atomic force microscopy. The concentrations of Ca and P were monitored as a function of time. The morphology of the precipitate layer seems to be dependent both on the type of metal substrate and its surface finish. Polished Ti-6A1-4V and Ti-Al-2.5Fe surfaces exhibit a plate precipitate morphology, whereas rougher surfaces show scattered crystal-like precipitation. The results suggest that the layer produced by immersion of polished titanium alloys in HBSS is constituted by an amorphous apatite.

Development of a new low cost antireflective coating technique for solar cells

NASA Technical Reports Server (NTRS)

Wohlgemuth, J. H.; Warfield, D. B.; Johnson, G. A.

1982-01-01

The goal of this study was the development of an antireflective (AR) coating technique that has the potential for high throughput and low cost yet is capable of producing films of good optical quality. Previous efforts to develop sprayed AR coatings had utilized titanium isopropoxide mixed with volatile solvents. These films worked well on smooth surfaces but when applied to etched semi-crystalline silicon surfaces yielded inconsistent results with more than 20 percent of the AM1 incident light being reflected. In this program titanium isopropoxide was sprayed directly onto heater wafers (410 C) to produce a uniform AR coating even on highly textured surfaces. Tests on various types of solar cells yielded performance improvements for the hot sprayed AR cells that are equivalent to that observed for evaporated TiOx AR coated cells. As an extension of this effort a new double layer AR consisting of a bottom layer of hot sprayed titanium isopropoxide and a top layer of hot sprayed aluminum isopropoxide in methylene chloride has resulted in more than 10 percent improvement in cell output as compared to a single layer AR cell.

Prediction and rational correlation of thermophoretically reduced particle mass transfer to hot surfaces across laminar or turbulent forced-convection gas boundary layers

NASA Technical Reports Server (NTRS)

Gokoglu, Suleyman A.; Rosner, Daniel E.

1986-01-01

A formulation previously developed to predict and correlate the thermophoretically-augmented submicron particle mass transfer rate to cold surfaces is found to account for the thermophoretically reduced particle mass transfer rate to overheated surfaces such that thermophoresis brings about a 10-decade reduction below the convective mass transfer rate expected by pure Brownian diffusion and convection alone. Thermophoretic blowing is shown to produce effects on particle concentration boundary-layer (BL) structure and wall mass transfer rates similar to those produced by real blowing through a porous wall. The applicability of the correlations to developing BL-situations is demonstrated by a numerical example relevant to wet-steam technology.

Theoretical study for heterojunction surface of NEA GaN photocathode dispensed with Cs activation

NASA Astrophysics Data System (ADS)

Xia, Sihao; Liu, Lei; Wang, Honggang; Wang, Meishan; Kong, Yike

2016-09-01

For the disadvantages of conventional negative electron affinity (NEA) GaN photocathodes activated by Cs or Cs/O, new-type NEA GaN photocathodes with heterojunction surface dispensed with Cs activation are investigated based on first-principle study with density functional theory. Through the growth of an ultrathin n-type GaN cap layer on p-type GaN emission layer, a p-n heterojunction is formed on the surface. According to the calculation results, it is found that Si atoms tend to replace Ga atoms to result in an n-type doped cap layer which contributes to the decreasing of work function. After the growth of n-type GaN cap layer, the atom structure near the p-type emission layer is changed while that away from the surface has no obvious variations. By analyzing the E-Mulliken charge distribution of emission surface with and without cap layer, it is found that the positive charge of Ga and Mg atoms in the emission layer decrease caused by the cap layer, while the negative charge of N atom increases. The conduction band moves downwards after the growth of cap layer. Si atom produces donor levels around the valence band maximum. The absorption coefficient of GaN emission layer decreases and the reflectivity increases caused by n-type GaN cap layer.

Titan's lower troposphere: thermal structure and dynamics

NASA Astrophysics Data System (ADS)

Charnay, B.; Lebonnois, S.

2011-12-01

A new climate model for Titan's atmosphere has been developed, using the physics of the IPSL Titan 2-dimensional climate model with the current version of the LMDZ General Circulation Model's dynamical core. The GCM covers altitudes from the surface to 500 km with the diurnal cycle and the gravitational tides included. 1. Boundary layer and thermal structure The HASI profile of potential temperature shows a layer at 300 m, an other at 800 m and a slope change at 2 km ([5],[2]). Dune spacing on Titan is consistent with a 2-3 km boundary layer ([3]). We have reproduced this profile (see figure) and interpreted the layer at 300 m as a convective boundary layer, the layer at 800 m is a residual layer corresponding to the maximum diurnal vertical extension of the PBL. We interpret the slope change at 2 km as produced by the seasonal displacement of the ITCZ. This layer traps the circulation in the first two km and is responsible of the dune spacing. Finally we interpret the fog discovered in summer polar region ([1]) has clouds produced by the diurnal cycle of the PBL (as fair weather cumulus on Earth). 2. Surface winds 2.1 Effect of gravitational and thermal tides We analysed tropospheric winds and the influence of both the thermal and the gravitational tides. The impact of gravitational tides on the circulation is extremely small. Thermal tides have a visible effect, though quite tenuous. 2.2 Effect of topography We produced topography maps derived from spherical harmonic interpolation ([6]) on the reference ellipsoid ([4]). Surface temperatures at high altitude appear higher that the ambient air. Vertical air movements produce anabatic winds developing on smooth and long slopes. This could be one of the main causes controlling the direction of surface winds and the direction of dunes. References [1] Brown et al.: Discovery of fog at the south pole of Titan, Astrophys. J. 706 (2009), pp. L110-L113 [2] Griffith et al.: Titan's Tropical Storms in an Evolving Atmosphere, Astrophys. J. 687 (2008) L41-L44. [3] Lorenz et al.: A 3 km atmospheric boundary layer on Titan indiacted by dune spacing and Huygens data, Icarus 205, 719-721 (2010) [4] Luciano Iess et al.: Gravity Field, Shape, and Moment of Inertia of Titan, Science 327, 1367(2010) [5] Tokano et al.: Titan's planetary boundary layer structure at the Huygens landing site, J. Geophys. Res vol. 111 (2006) [6] HA. Zebker et al.: Size and Shape of Saturn's Moon TitanScience 324, 921(2009)

Particle detector spatial resolution

DOEpatents

Perez-Mendez, V.

1992-12-15

Method and apparatus for producing separated columns of scintillation layer material, for use in detection of X-rays and high energy charged particles with improved spatial resolution is disclosed. A pattern of ridges or projections is formed on one surface of a substrate layer or in a thin polyimide layer, and the scintillation layer is grown at controlled temperature and growth rate on the ridge-containing material. The scintillation material preferentially forms cylinders or columns, separated by gaps conforming to the pattern of ridges, and these columns direct most of the light produced in the scintillation layer along individual columns for subsequent detection in a photodiode layer. The gaps may be filled with a light-absorbing material to further enhance the spatial resolution of the particle detector. 12 figs.

Particle detector spatial resolution

DOEpatents

Perez-Mendez, Victor

1992-01-01

Method and apparatus for producing separated columns of scintillation layer material, for use in detection of X-rays and high energy charged particles with improved spatial resolution. A pattern of ridges or projections is formed on one surface of a substrate layer or in a thin polyimide layer, and the scintillation layer is grown at controlled temperature and growth rate on the ridge-containing material. The scintillation material preferentially forms cylinders or columns, separated by gaps conforming to the pattern of ridges, and these columns direct most of the light produced in the scintillation layer along individual columns for subsequent detection in a photodiode layer. The gaps may be filled with a light-absorbing material to further enhance the spatial resolution of the particle detector.

Convection-Diffusion Layer in an "Open Space" for Local Surface Treatment and Microfabrication using a Four-Aperture Microchemical Pen.

PubMed

Mao, Sifeng; Zhang, Yong; Zhang, Weifei; Zeng, Hulie; Nakajima, Hizuru; Lin, Jin-Ming; Uchiyama, Katsumi

2017-09-06

A four-aperture microchemical pen was used to produce a stable convection-diffusion layer in an "open space" for microreactions and microfabrication. The process represents a new method for microreactions and microfabrication in a convection-diffusion layer. To prove the concept of a convection-diffusion layer in an "open space", bovine serum albumin was labeled with 4-fluoro-7-nitro-2,1,3-benzoxadiazole to confirm that the small convection-diffusion layer was effective for local surface treatment. To demonstrate the potential for microfabrication, silver patterns were fabricated on a glass surface with a convection-diffusion layer by using the silver-mirror reaction. The widths of each silver pattern could be easily controlled from 10 to 60 μm. Patterned silver lines with uniform widths or gradient widths were prepared. This is the first proof of concept study of a convection-diffusion layer in an "open space" used in local surface treatment and microfabrication on a surface. The microchemical pen represents a potential method for the region-selective microtreatment of tissues, cells, and other biological interfaces. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Molecular beam epitaxial growth and structural characterization of ZnS on (001) GaAs

NASA Technical Reports Server (NTRS)

Benz, R. G., II; Huang, P. C.; Stock, S. R.; Summers, C. J.

1988-01-01

The effect of surface nucleation processes on the quality of ZnS layers grown on (001) GaAs substrates by molecular beam epitaxy is reported. Reflection high energy electron diffraction indicated that nucleation at high temperatures produced more planar surfaces than nucleation at low temperatures, but the crystalline quality as assessed by X-ray double crystal diffractometry is relatively independent of nucleation temperature. A critical factor in layer quality was the initial roughness of the GaAs surfaces.

Cryogenic target formation using cold gas jets

DOEpatents

Hendricks, C.D.

1980-02-26

A method and apparatus using cold gas jets for producing a substantially uniform layer of cryogenic materials on the inner surface of hollow spherical members having one or more layers, such as inertially imploded targets are disclosed. By vaporizing and quickly refreezing cryogenic materials contained within a hollow spherical member, a uniform layer of the materials is formed on an inner surface of the spherical member. Basically the method involves directing cold gas jets onto a spherical member having one or more layers or shells and containing the cryogenic material, such as a deuterium-tritium (DT) mixture, to freeze the contained material, momentarily heating the spherical member so as to vaporize the contained material, and quickly refreezing the thus vaporized material forming a uniform layer of cryogenic material on an inner surface of the spherical member. 4 figs.

High efficiency low cost thin film silicon solar cell design and method for making

DOEpatents

Sopori, B.L.

1999-04-27

A semiconductor device is described having a substrate, a conductive intermediate layer deposited onto said substrate, wherein the intermediate layer serves as a back electrode, an optical reflector, and an interface for impurity gettering, and a semiconductor layer deposited onto said intermediate layer, wherein the semiconductor layer has a grain size at least as large as the layer thickness, and preferably about ten times the layer thickness. The device is formed by depositing a metal layer on a substrate, depositing a semiconductive material on the metal-coated substrate to produce a composite structure, and then optically processing the composite structure by illuminating it with infrared electromagnetic radiation according to a unique time-energy profile that first produces pits in the backside surface of the semiconductor material, then produces a thin, highly reflective, low resistivity alloy layer over the entire area of the interface between the semiconductor material and the metal layer, and finally produces a grain-enhanced semiconductor layer. The time-energy profile includes increasing the energy to a first energy level to initiate pit formation and create the desired pit size and density, then ramping up to a second energy level in which the entire device is heated to produce an interfacial melt, and finally reducing the energy to a third energy level and holding for a period of time to allow enhancement in the grain size of the semiconductor layer. 9 figs.

Aluminum Coating Influence on Nitride Layer Performance Deposited by MO-CVD in Fluidized Bed on Austenitic Stainless Steel Substrate

NASA Astrophysics Data System (ADS)

Găluşcă, D. G.; Perju, M. C.; Nejneru, C.; Burduhos Nergiş, D. D.; Lăzărescu, I. E.

2018-06-01

The modification of surface properties by duplex treatments, involving the overlapping of two surface treatment techniques, has been established as an intelligent solution to create new applications for the substrate metallic material. There are driveline components operating under very tough wear and corrosion conditions, with high temperature and humidity variations. Such components are usually made of high Cr and Ni stainless steel and for the hardening of surfaces it is recommended a thermo chemical treatment. Since stainless steels, especially austenitic stainless steels, are difficult to nitride, experimental studies focus on increasing the depth of the nitride layer and surface hardness. Achieving the goal involves changing active layer chemical composition by introducing aluminum in the surface layer. In order to find a solution, a new surface treatment technique is produced by combining aluminum thin films by MO-CVD in a fluidized bed using a triisobutylaluminum precursor with a thermo chemical nitriding treatment.

Methods and apparatus for producing cryogenic inertially driven fusion targets

DOEpatents

Miller, John R.

1981-01-01

A new technique for producing uniform layers of solid DT on microballoon surfaces. Local heating of the target, typically by means of a focused laser, within an isothermal freezing cell containing a low pressure cryogenic exchange gas such as helium, vaporizes the DT fuel. Removal of the laser heating source causes the DT gas to rapidly condense and freeze in a layer which exhibits a good degree of uniformity.

Effect of a Dusty Layer on Surface-Wave Produced Plasmas

NASA Astrophysics Data System (ADS)

Ostrikov, Kostyantyn; Yu, Ming; Xu, Shuyan

2000-10-01

The effect of near-sheath dusts on the RF power loss in a surface-wave sustained gas discharge is studied. The planar plasma is bounded by a dielectric and consists of an inhomogeneous near-wall transition layer (sheath), a dusty plasma layer, and the outer dust-free plasma. The discharge is maintained by high-frequency axially-symmetric surface waves. The surface-wave power loss from the most relevant dissipative mechanisms in typical discharge plasmas is analyzed. Our model allows one to consider the main effects of dust particles on surface-wave produced discharge plasmas. We demonstrate that the dusts released in the discharge can strongly modify the plasma conductivity and lead to a significant redistribution of the total charge. They affect the electron quasi-momenta, but do not absorb the energy transmitted to the plasma through elastic collisions, and therefore they remain cold at the room temperature. It is shown that the improvement of the efficiency of energy transfer from the wave source to the plasma can be achieved by selecting operation regimes when the efficiency of the power loss in the plasma through electron-neutral collisions is higher than that through electron-dust interactions.

Combined surface hardening and laser patterning approach for functionalising stainless steel surfaces

NASA Astrophysics Data System (ADS)

Garcia-Giron, A.; Romano, J. M.; Liang, Y.; Dashtbozorg, B.; Dong, H.; Penchev, P.; Dimov, S. S.

2018-05-01

The paper reports a laser patterning method for producing surfaces with dual scale topographies on ferritic stainless steel plates that are hardened by low temperature plasma surface alloying. Nitrogen and carbon based gasses were used in the alloying process to obtain surface layers with an increased hardness from 172 HV to 1001 HV and 305 HV, respectively. Then, a nanosecond infrared laser was used to pattern the plasma treated surfaces and thus to obtain super-hydrophobicity, by creating cell- or channel-like surface structures. The combined surface hardening and laser patterning approach allowed super-hydrophobic surfaces to be produced on both nitrided and carburised stainless steel plates with effective contact angles higher than 150°. The hardened layers on nitrided samples had cracks and was delaminated after the laser patterning while on plasma carburised samples remained intact. The results showed that by applying the proposed combined approach it is possible to retain the higher hardness of the nitrided stainless steel plates and at the same time to functionalise them to obtain super-hydrophobic properties.

Enzyme Armoring by an Organosilica Layer: Synthesis and Characterization of Hybrid Organic/Inorganic Nanobiocatalysts.

PubMed

Correro, M Rita; Sykora, Sabine; Corvini, Philippe F-X; Shahgaldian, Patrick

2017-01-01

The availability of highly stable and reusable enzymes is one of the main challenges in bio-based industrial processes. Enzyme immobilization and encapsulation represent promising strategies to reach this goal. In this chapter, the synthetic strategy to produce hybrid organic/inorganic nanobiocatalysts (NBC) is reported. This strategy is based on the sequential immobilization of an enzyme on the surface of silica nanoparticles followed by the growth, at the surface of the nanoparticles, of a shielding layer which serves as an armor to protect the enzyme against denaturation/degradation. This armor is produced through a thickness-controlled organosilane poly-condensation onto the nanoparticle surface around the enzyme to form a protective organosilica layer. The armored nanobiocatalysts present enhanced catalytic activity and improved stability against heat, pH, chaotropic agents, proteases, and ultrasound. The method is versatile in that it can be successfully adapted to a number of different enzymes. © 2017 Elsevier Inc. All rights reserved.

Process for the production of star-tracking reticles

NASA Technical Reports Server (NTRS)

Toft, A. R.; Smith, W. O.

1974-01-01

Reticles designed with quartz bases are masked with desired pattern and then are coated with highly adherent layers of chromium, chromium silver alloy, silver, copper, and black chromium (mixture of chromium and chromium oxides). Black chromium final layer produces required nonreflective surface.

Oceanographic, Air-sea Interaction, and Environmental Aspects of Artificial Upwelling Produced by Wave-Inertia Pumps for Potential Hurricane Intensity Mitigation

NASA Astrophysics Data System (ADS)

Soloviev, A.; Dean, C.

2017-12-01

The artificial upwelling system consisting of the wave-inertia pumps driven by surface waves can produce flow of cold deep water to the surface. One of the recently proposed potential applications of the artificial upwelling system is the hurricane intensity mitigation. Even relatively small reduction of intensity may provide significant benefits. The ocean heat content (OHC) is the "fuel" for hurricanes. The OHC can be reduced by mixing of the surface layer with the cold water produced by wave-inertia pumps. Implementation of this system for hurricane mitigation has several oceanographic and air-sea interaction aspects. The cold water brought to the surface from a deeper layer has higher density than the surface water and, therefore, tends to sink back down. The mixing of the cold water produced by artificial upwelling depends on environmental conditions such as stratification, regional ocean circulation, and vertical shear. Another aspect is that as the sea surface temperature drops below the air temperature, the stable stratification develops in the atmospheric boundary layer. The stable atmospheric stratification suppresses sensible and latent heat air-sea fluxes and reduces the net longwave irradiance from the sea surface. As a result, the artificial upwelling may start increasing the OHC (though still reducing the sea surface temperature). In this work, the fate of the cold water in the stratified environment with vertical shear has been studied using computational fluid dynamics (CFD) tools. A 3D large eddy simulation model is initialized with observational temperature, salinity, and current velocity data from a sample location in the Straits of Florida. A periodic boundary condition is set along the direction of the current, which allows us to simulate infinite fetch. The model results indicate that the cold water brought to the sea surface by a wave-inertia pump forms a convective jet. This jet plunges into the upper ocean mixed layer and penetrates the thermocline. On the way down, the jet partially mixes with the surrounding water reducing the temperature of the upper ocean. The OHC thus can either reduce or increase, depending on the wave-inertia pump parameters. Based on the model results, we discuss feasibility of the implementation of the artificial upwelling system for hurricane intensity mitigation.

The Epiregolith

NASA Technical Reports Server (NTRS)

Mendell, Wendell W.; Noble, S. K.

2010-01-01

The physical properties of the lunar regolith were originally inferred from remotely sensed data, first from the Earth and later from orbiting spacecraft. The Surveyor landings and the Apollo surface explorations produced a more concrete characterization of the macroscopic properties. In general, the upper regolith consists of a loosely consolidated layer centimeters thick underlain by a particulate but extremely compacted layer to depths of meters or tens of meters. The median particle size as determined by mechanical sieving in terrestrial laboratories is several tens of micrometers. However, the comminuting processes that form the layer produce particles in all sizes down to manometers. The smallest particles, having a high surface to volume ratio, tend to be electrostatically bound to larger particles and are quite difficult to separate mechanically in the laboratory. Particle size distributions determined from lunar soil samples often group particles smaller than 10 micrometers.

Aligned and Electrospun Piezoelectric Polymer Fiber Assembly and Scaffold

NASA Technical Reports Server (NTRS)

Holloway, Nancy M. (Inventor); Scott-Carnell, Lisa A. (Inventor); Siochi, Emilie J. (Inventor); Leong, Kam W. (Inventor); Kulangara, Karina (Inventor)

2015-01-01

A scaffold assembly and related methods of manufacturing and/or using the scaffold for stem cell culture and tissue engineering applications are disclosed which at least partially mimic a native biological environment by providing biochemical, topographical, mechanical and electrical cues by using an electroactive material. The assembly includes at least one layer of substantially aligned, electrospun polymer fiber having an operative connection for individual voltage application. A method of cell tissue engineering and/or stem cell differentiation uses the assembly seeded with a sample of cells suspended in cell culture media, incubates and applies voltage to one or more layers, and thus produces cells and/or a tissue construct. In another aspect, the invention provides a method of manufacturing the assembly including the steps of providing a first pre-electroded substrate surface; electrospinning a first substantially aligned polymer fiber layer onto the first surface; providing a second pre-electroded substrate surface; electrospinning a second substantially aligned polymer fiber layer onto the second surface; and, retaining together the layered surfaces with a clamp and/or an adhesive compound.

Aligned and Electrospun Piezoelectric Polymer Fiber Assembly and Scaffold

NASA Technical Reports Server (NTRS)

Kulangara, Karina (Inventor); Scott Carnell, Lisa A. (Inventor); Holloway, Nancy M. (Inventor); Leong, Kam W. (Inventor); Siochi, Emilie J. (Inventor)

2017-01-01

A method of manufacturing and/or using a scaffold assembly for stem cell culture and tissue engineering applications is disclosed. The scaffold at least partially mimics a native biological environment by providing biochemical, topographical, mechanical and electrical cues by using an electroactive material. The assembly includes at least one layer of substantially aligned, electrospun polymer fiber having an operative connection for individual voltage application. A method of cell tissue engineering and/or stem cell differentiation that uses the assembly seeded with a sample of cells suspended in cell culture media, incubates and applies voltage to one or more layers, and thus produces cells and/or a tissue construct. In another aspect, the invention provides a method of manufacturing the assembly including the steps of providing a first pre-electroded substrate surface; electrospinning a first substantially aligned polymer fiber layer onto the first surface; providing a second pre-electroded substrate surface; electrospinning a second substantially aligned polymer fiber layer onto the second surface; and, retaining together the layered surfaces with a clamp and/or an adhesive compound.

Passivation of uranium towards air corrosion by N 2+ and C + ion implantation

NASA Astrophysics Data System (ADS)

Arkush, R.; Mintz, M. H.; Shamir, N.

2000-10-01

The passivation of uranium surfaces against air corrosion, by ion implantation processes was studied, using surface analysis methods. Implanting 45 keV N +2 and C + ions produces thin modified surface layers with gradual gradients of the corresponding compounds (i.e., nitrides and carbides, respectively), which avoid the formation of discontinuous interfaces typical to coatings. Such gradual interfaces impart excellent mechanical stability and adhesion to the modified layers, in spite of the large misfit between the metal substrate and the implantation on induced compounds. It turns out that these layers provide an almost absolute protection against air corrosion. A rapid initial stage of oxidation of the modified surface layers takes place, forming very thin protective oxidation zones (1-4 nm thick), which practically stop further air oxidation for years. The mechanism of the initial oxidation stage of the modified layers seems to vary with the type of surface (i.e., either nitrides or carbides). However, in any case the protection ability of the formed oxidation products is excellent, probably due to the close match between these compounds and the underlying nitrides or carbides.

Process Produces Low-Secondary-Electron-Emission Surfaces

NASA Technical Reports Server (NTRS)

Curren, A. N.; Jensen, K. A.; Roman, R. F.

1986-01-01

Textured carbon layer applied to copper by sputtering. Carbon surface characterized by dense, random array of needle-like spires or peaks that extend perpendicularly from local copper surface. Spires approximately 7 micrometers in height and spaced approximately 3 micrometers apart, on average. Copper substrate essentially completely covered by carbon layer, is tenacious and not damaged by vibration loadings representative of multistage depressed collector (MDC) applications. Process developed primarily to provide extremely low-secondary-electron-emission surface for copper for use as highefficiency electrodes in MDC's for microwave amplifier traveling-wave tubes (TWT's). Tubes widely used in space communications, aircraft, and terrestrial applications.

The Surface Structure of Ground Metal Crystals

NASA Technical Reports Server (NTRS)

Boas, W.; Schmid, E.

1944-01-01

The changes produced on metallic surfaces as a result of grinding and polishing are not as yet fully understood. Undoubtedly there is some more or less marked change in the crystal structure, at least, in the top layer. Hereby a diffusion of separated crystal particles may be involved, or, on plastic material, the formation of a layer in greatly deformed state, with possible recrystallization in certain conditions. Czochralski verified the existence of such a layer on tin micro-sections by successive observations of the texture after repeated etching; while Thomassen established, roentgenographically by means of the Debye-Scherrer method, the existence of diffused crystal fractions on the surface of ground and polished tin bars, which he had already observed after turning (on the lathe). (Thickness of this layer - 0.07 mm). Whether this layer borders direct on the undamaged base material or whether deformed intermediate layers form the transition, nothing is known. One observation ty Sachs and Shoji simply states that after the turning of an alpha-brass crystal the disturbance starting from the surface, penetrates fairly deep (approx. 1 mm) into the crystal (proof by recrystallization at 750 C).

Fabrication mechanism of friction-induced selective etching on Si(100) surface

PubMed Central

2012-01-01

As a maskless nanofabrication technique, friction-induced selective etching can easily produce nanopatterns on a Si(100) surface. Experimental results indicated that the height of the nanopatterns increased with the KOH etching time, while their width increased with the scratching load. It has also found that a contact pressure of 6.3 GPa is enough to fabricate a mask layer on the Si(100) surface. To understand the mechanism involved, the cross-sectional microstructure of a scratched area was examined, and the mask ability of the tip-disturbed silicon layer was studied. Transmission electron microscope observation and scanning Auger nanoprobe analysis suggested that the scratched area was covered by a thin superficial oxidation layer followed by a thick distorted (amorphous and deformed) layer in the subsurface. After the surface oxidation layer was removed by HF etching, the residual amorphous and deformed silicon layer on the scratched area can still serve as an etching mask in KOH solution. The results may help to develop a low-destructive, low-cost, and flexible nanofabrication technique suitable for machining of micro-mold and prototype fabrication in micro-systems. PMID:22356699

Fabrication mechanism of friction-induced selective etching on Si(100) surface.

PubMed

Guo, Jian; Song, Chenfei; Li, Xiaoying; Yu, Bingjun; Dong, Hanshan; Qian, Linmao; Zhou, Zhongrong

2012-02-23

As a maskless nanofabrication technique, friction-induced selective etching can easily produce nanopatterns on a Si(100) surface. Experimental results indicated that the height of the nanopatterns increased with the KOH etching time, while their width increased with the scratching load. It has also found that a contact pressure of 6.3 GPa is enough to fabricate a mask layer on the Si(100) surface. To understand the mechanism involved, the cross-sectional microstructure of a scratched area was examined, and the mask ability of the tip-disturbed silicon layer was studied. Transmission electron microscope observation and scanning Auger nanoprobe analysis suggested that the scratched area was covered by a thin superficial oxidation layer followed by a thick distorted (amorphous and deformed) layer in the subsurface. After the surface oxidation layer was removed by HF etching, the residual amorphous and deformed silicon layer on the scratched area can still serve as an etching mask in KOH solution. The results may help to develop a low-destructive, low-cost, and flexible nanofabrication technique suitable for machining of micro-mold and prototype fabrication in micro-systems.

Mechanical properties of nitrogen-rich surface layers on SS304 treated by plasma immersion ion implantation

NASA Astrophysics Data System (ADS)

Fernandes, B. B.; Mändl, S.; Oliveira, R. M.; Ueda, M.

2014-08-01

The formation of hard and wear resistant surface regions for austenitic stainless steel through different nitriding and nitrogen implantation processes at intermediate temperatures is an established technology. As the inserted nitrogen remains in solid solution, an expanded austenite phase is formed, accounting for these surface improvements. However, experiments on long-term behavior and exact wear processes within the expanded austenite layer are still missing. Here, the modified layers were produced using plasma immersion ion implantation with nitrogen gas and had a thickness of up to 4 μm, depending on the processing temperature. Thicker layers or those with higher surface nitrogen contents presented better wear resistance, according to detailed microscopic investigation on abrasion, plastic deformation, cracking and redeposition of material inside the wear tracks. At the same time, cyclic fatigue testing employing a nanoindenter equipped with a diamond ball was carried out at different absolute loads and relative unloadings. As the stress distribution between the modified layer and the substrate changes with increasing load, additional simulations were performed for obtaining these complex stress distributions. While high nitrogen concentration and/or thicker layers improve the wear resistance and hardness, these modifications simultaneously reduce the surface fatigue resistance.

Mitigation of substrate defects in reticles using multilayer buffer layers

DOEpatents

Mirkarimi, Paul B.; Bajt, Sasa; Stearns, Daniel G.

2001-01-01

A multilayer film is used as a buffer layer to minimize the size of defects on a reticle substrate prior to deposition of a reflective coating on the substrate. The multilayer buffer layer deposited intermediate the reticle substrate and the reflective coating produces a smoothing of small particles and other defects on the reticle substrate. The reduction in defect size is controlled by surface relaxation during the buffer layer growth process and by the degree of intermixing and volume contraction of the materials at the multilayer interfaces. The buffer layers are deposited at near-normal incidence via a low particulate ion beam sputtering process. The growth surface of the buffer layer may also be heated by a secondary ion source to increase the degree of intermixing and improve the mitigation of defects.

Trampoline Effect: Observations and Modeling

NASA Astrophysics Data System (ADS)

Guyer, R.; Larmat, C. S.; Ulrich, T. J.

2009-12-01

The Iwate-Miyagi earthquake at site IWTH25 (14 June 2008) had large, asymmetric at surface vertical accelerations prompting the sobriquet trampoline effect (Aoi et. al. 2008). In addition the surface acceleration record showed long-short waiting time correlations and vertical-horizontal acceleration correlations. A lumped element model, deduced from the equations of continuum elasticity, is employed to describe the behavior at this site in terms of a surface layer and substrate. Important ingredients in the model are the nonlinear vertical coupling between the surface layer and the substrate and the nonlinear horizontal frictional coupling between the surface layer and the substrate. The model produces results in qualitative accord with observations: acceleration asymmetry, Fourier spectrum, waiting time correlations and vertical acceleration-horizontal acceleration correlations. [We gratefully acknowledge the support of the U. S. Department of Energy through the LANL/LDRD Program for this work].

Characterisation of thin films of graphene–surfactant composites produced through a novel semi-automated method

PubMed Central

Nabok, Alexei; Davis, Frank; Higson, Séamus P J

2016-01-01

Summary In this paper we detail a novel semi-automated method for the production of graphene by sonochemical exfoliation of graphite in the presence of ionic surfactants, e.g., sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB). The formation of individual graphene flakes was confirmed by Raman spectroscopy, while the interaction of graphene with surfactants was proven by NMR spectroscopy. The resulting graphene–surfactant composite material formed a stable suspension in water and some organic solvents, such as chloroform. Graphene thin films were then produced using Langmuir–Blodgett (LB) or electrostatic layer-by-layer (LbL) deposition techniques. The composition and morphology of the films produced was studied with SEM/EDX and AFM. The best results in terms of adhesion and surface coverage were achieved using LbL deposition of graphene(−)SDS alternated with polyethyleneimine (PEI). The optical study of graphene thin films deposited on different substrates was carried out using UV–vis absorption spectroscopy and spectroscopic ellipsometry. A particular focus was on studying graphene layers deposited on gold-coated glass using a method of total internal reflection ellipsometry (TIRE) which revealed the enhancement of the surface plasmon resonance in thin gold films by depositing graphene layers. PMID:26977378

New insight in the nature of surface magnetic anisotropy in iron borate

NASA Astrophysics Data System (ADS)

Strugatsky, M.; Seleznyova, K.; Zubov, V.; Kliava, J.

2018-02-01

The theory of surface magnetism of iron borate, FeBO3, has been extended by taking into consideration a crystal field contribution to the surface magnetic anisotropy energy. For this purpose, a model of distortion of the six-fold oxygen environment of iron ions in the near-surface layer of iron borate has been put forward. The spin Hamiltonian parameters for isolated Fe3+ ions in the distorted environment of the near-surface layer have been calculated using the Newman's superposition model. The crystal field contribution to the surface magnetic anisotropy energy has been calculated in the framework of the perturbation theory. The model developed allows concluding that the distortions of the iron environment produce a significant crystal field contribution to the surface magnetic anisotropy constant. The results of experimental studies of the surface magnetic anisotropy in iron borate can be described assuming the existence of relative contractions in the near-surface layer of the order of 1 %.

Apparatus for producing cryogenic inertially driven fusion targets

DOEpatents

Miller, John R.

1981-01-01

A new technique for producing uniform layers of solid DT on microballoon surfaces. Local heating of the target, typically by means of a focused laser, within an isothermal freezing cell containing a low pressure cryogenic exchange gas such as helium, vaporizes the DT fuel contained within the microballoon. Removal of the laser heating source causes the DT gas to rapidly condense and freeze in a layer which exhibits a good degree of uniformity.

Modeling of reduced secondary electron emission yield from a foam or fuzz surface

DOE PAGES

Swanson, Charles; Kaganovich, Igor D.

2018-01-10

Complex structures on a material surface can significantly reduce the total secondary electron emission yield from that surface. A foam or fuzz is a solid surface above which is placed a layer of isotropically aligned whiskers. Primary electrons that penetrate into this layer produce secondary electrons that become trapped and do not escape into the bulk plasma. In this manner the secondary electron yield (SEY) may be reduced. We developed an analytic model and conducted numerical simulations of secondary electron emission from a foam to determine the extent of SEY reduction. We find that the relevant condition for SEY minimization ismore » $$\\bar{u}$$≡AD/2>>1 while D <<1, where D is the volume fill fraction and A is the aspect ratio of the whisker layer, the ratio of the thickness of the layer to the radius of the fibers. As a result, we find that foam cannot reduce the SEY from a surface to less than 0.3 of its flat value.« less

Modeling of reduced secondary electron emission yield from a foam or fuzz surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swanson, Charles; Kaganovich, Igor D.

Complex structures on a material surface can significantly reduce the total secondary electron emission yield from that surface. A foam or fuzz is a solid surface above which is placed a layer of isotropically aligned whiskers. Primary electrons that penetrate into this layer produce secondary electrons that become trapped and do not escape into the bulk plasma. In this manner the secondary electron yield (SEY) may be reduced. We developed an analytic model and conducted numerical simulations of secondary electron emission from a foam to determine the extent of SEY reduction. We find that the relevant condition for SEY minimization ismore » $$\\bar{u}$$≡AD/2>>1 while D <<1, where D is the volume fill fraction and A is the aspect ratio of the whisker layer, the ratio of the thickness of the layer to the radius of the fibers. As a result, we find that foam cannot reduce the SEY from a surface to less than 0.3 of its flat value.« less

Nanopatterned articles produced using surface-reconstructed block copolymer films

DOEpatents

Russell, Thomas P.; Park, Soojin; Wang, Jia-Yu; Kim, Bokyung

2016-06-07

Nanopatterned surfaces are prepared by a method that includes forming a block copolymer film on a substrate, annealing and surface reconstructing the block copolymer film to create an array of cylindrical voids, depositing a metal on the surface-reconstructed block copolymer film, and heating the metal-coated block copolymer film to redistribute at least some of the metal into the cylindrical voids. When very thin metal layers and low heating temperatures are used, metal nanodots can be formed. When thicker metal layers and higher heating temperatures are used, the resulting metal structure includes nanoring-shaped voids. The nanopatterned surfaces can be transferred to the underlying substrates via etching, or used to prepare nanodot- or nanoring-decorated substrate surfaces.

Adsorption studies of simple gases on As-produced single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Talapatra, Saikat

Adsorption isotherms measurements were used to study films of Xenon (Xe), Argon (Ar), Methane (CH4), Hydrogen (H2) and Neon (Ne) adsorbed on bundles of as-produced Single Walled Carbon Nanotubes (SWNT). A comparison of the specific surface areas of the SWNT samples measured with these various gases, as well as a comparison of the binding energies measured for each of them on the SWNT bundles; allows us to infer which of the possible groups of adsorption sites on the SWNT bundles are actually occupied by the adsorbed gases. The presence of substeps in the first layer isotherm data establishes the existence of different phases within the first layer film. A detailed comparison of our experimental results to recent computer simulations for these systems is done. This allows us to determine the nature of the phases present in the first layer. Evidence of the formation of a one-dimensional phase in the second layer film (i.e. the film that forms after the entire surface of the bundles is covered by one layer of gas) is observed in these studies. The sharpness of this second layer feature varies as a function of the molecular diameter of the adsorbate.

Small phytoplankton and carbon export from the surface ocean.

PubMed

Richardson, Tammi L; Jackson, George A

2007-02-09

Autotrophic picoplankton dominate primary production over large oceanic regions but are believed to contribute relatively little to carbon export from surface layers. Using analyses of data from the equatorial Pacific Ocean and Arabian Sea, we show that the relative direct and indirect contribution of picoplankton to export is proportional to their total net primary production, despite their small size. We suggest that all primary producers, not just the large cells, can contribute to export from the surface layer of the ocean at rates proportional to their production rates.

Effect of Induced Charge Electroosmosis on the Dielectrophoretic Motion of Particles

NASA Astrophysics Data System (ADS)

Swaminathan, T.; Hu, Howard

2006-11-01

Most suspensions involve the formation of ionic double layers next to the surface of particles due to the induced-charge on the surface. These double layers affect the motion of the particle even under AC electric fields. They modify the net dipole moment of the particle and at the same time produce slip velocities on the surfaces of these particles. A method to numerically evaluate the effect of the double layer on the dielectrophoretic motion of particles has been previously developed to study these two effects. The technique involves a matched asymptotic expansion of the electric field near the particle surface, where the double layer is formed, and is written as a jump-boundary-condition for the electric potential when the thickness of the double layer is small compared to the size of the particle. The developed jump-boundary-condition is then used to calculate an effective zeta potential on the particle surface. Unlike classical electroosmosis, this zeta potential is no longer constant on every part of the surface and is dependent on the applied electric field. The effect of the induced-charge electroosmotic slip velocity on the dielectrophoretic motion of particles has been observed using this technique.

Intermolecular and interfacial forces: Elucidating molecular mechanisms using chemical force microscopy

NASA Astrophysics Data System (ADS)

Ashby, Paul David

Investigation into the origin of forces dates to the early Greeks. Yet, only in recent decades have techniques for elucidating the molecular origin of forces been developed. Specifically, Chemical Force Microscopy uses the high precision and nanometer scale probe of Atomic Force Microscopy to measure molecular and interfacial interactions. This thesis presents the development of many novel Chemical Force Microscopy techniques for measuring equilibrium and time-dependant force profiles of molecular interactions, which led to a greater understanding of the origin of interfacial forces in solution. In chapter 2, Magnetic Feedback Chemical Force Microscopy stiffens the cantilever for measuring force profiles between self-assembled monolayer (SAM) surfaces. Hydroxyl and carboxyl terminated SAMs produce long-range interactions that extend one or three nanometers into the solvent, respectively. In chapter 3, an ultra low noise AFM is produced through multiple modifications to the optical deflection detection system and signal processing electronics. In chapter 4, Brownian Force Profile Reconstruction is developed for accurate measurement of steep attractive interactions. Molecular ordering is observed for OMCTS, 1-nonanol, and water near flat surfaces. The molecular ordering of the solvent produces structural or solvation forces, providing insight into the orientation and possible solidification of the confined solvent. Seven molecular layers of OMCTS are observed but the oil remains fluid to the last layer. 1-nonanol strongly orders near the surface and becomes quasi-crystalline with four layers. Water is oriented by the surface and symmetry requires two layers of water (3.7 A) to be removed simultaneously. In chapter 5, electronic control of the cantilever Q (Q-control) is used to obtain the highest imaging sensitivity. In chapter 6, Energy Dissipation Chemical Force Microscopy is developed to investigate the time dependence and dissipative characteristics of SAM interfacial interactions in solution. Long-range adhesive forces for hydroxyl and carboxyl terminated SAM surfaces arise from solvent, not ionic, interactions. Exclusion of the solvent and contact between the SAM surfaces leads to rearrangement of the SAM headgroups. The isolation of the chemical and physical interfacial properties from the topography by Energy Dissipation Chemical Force Microscopy produces a new quantitative high-sensitivity imaging mode.

The role of surface chemical analysis in a study to select replacement processes for TCA vapor degreasing

NASA Technical Reports Server (NTRS)

Lesley, Michael W.; Davis, Lawrence E.; Moulder, John F.; Carlson, Brad A.

1995-01-01

The role of surface-sensitive chemical analysis (ESCA, AES, and SIMS) in a study to select a process to replace 1, 1, 1-trichloroethane (TCA) vapor degreasing as a steel and aluminum bonding surface preparation method is described. The effort was primarily concerned with spray-in-air cleaning processes involving aqueous alkaline and semi-aqueous cleaners and a contamination sensitive epoxy-to-metal bondline. While all five cleaners tested produced bonding strength results equal to or better than those produced by vapor degreasing, the aqueous alkaline cleaners yielded results which were superior to those produced by the semi-aqueous cleaners. The main reason for the enhanced performance appears to be a silicate layer left behind by the aqueous alkaline cleaners. The silicate layer increases the polarity of the surface and enhances epoxy-to-metal bonding. On the other hand, one of the semi-aqueous cleaners left a nonpolar carbonaceous residue which appeared to have a negative effect on epoxy-to-metal bonding. Differences in cleaning efficiency between cleaners/processes were also identified. These differences in surface chemistry, which were sufficient to affect bonding, were not detected by conventional chemical analysis techniques.

Method for producing functionally graded nanocrystalline layer on metal surface

DOEpatents

Ajayi, Oyelayo O.; Hershberger, Jeffrey G.

2010-03-23

An improved process for the creation or formation of nanocrystalline layers on substrates' surfaces is provided. The process involves "prescuffing" the surface of a substrate such as a metal by allowing friction to occur on the surface by a load-bearing entity making rubbing contact and moving along and on the substrate's surface. The "prescuffing" action is terminated when the coefficient of friction between the surface and the noise is rising significantly. Often, the significant rise in the coefficient of friction is signaled by a change in pitch of the scuffing action sound emanating from the buffeted surface. The "prescuffing" gives rise to a harder and smoother surface which withstands better any inadequate lubrication that may take place when the "prescuffed" surface is contacted by other surfaces.

Surface Modification of Titanium Using Anodization to Enhance Antimicrobial Properties and Osseointegration

NASA Astrophysics Data System (ADS)

Jain, Sakshi

Titanium and its alloys are frequently used in dental and orthopedic implants because they have good mechanical strength, chemical stability and biocompatibility. These properties can be further improved by surface treatments such as anodization that are able to grow thicker and produce crystalline oxide layers with controlled morphological and physico-chemical properties. Both anatase (A) and rutile (R) crystalline phases of titanium oxide have been shown to promote bioactivity and antimicrobial effects. In a previous study in our laboratories, four electrolyte mixtures were optimized to produce anodized layers on commercially pure titanium consisting of specific anatase and rutile oxide ratios at an endpoint forming voltage of 180 V. In the present study, changes that occurred in the anodized layers with increasing forming voltage including crystallinity, thickness, surface morphology, surface roughness, surface chemistry, fractal dimension, shear strength, and corrosion resistance were determined for each of these electrolytes. The results showed the crystallinity, thickness, surface pore sizes, and surface roughness increased with increasing forming voltage. Incorporation of phosphorus into the anodized layers was shown in phosphoric acid containing electrolytes at higher forming voltages. Decreases in corrosion resistance were also shown at higher forming voltages in each electrolyte due to increased pore interconnectivity within the anodized layers. In addition, the apatite inducing ability of anodized layers in SBF was examined for selected forming voltages in each electrolyte. Anodization in phosphoric acid containing electrolytes was shown to be more favorable for apatite formation. The streptococcal and MRSA bacterial attachment before and after UV treatments was determined for selected forming voltages in each electrolyte. Additionally, the killing efficacy after 10-minute pre-irradiation with UVA or UVC treatments was determined. UVA treatments showed trends of at least a 20% reduction in bacterial attachment regardless of the crystallinity within the oxide for S. sanguinis. The anodized layer with an approximately equal distribution of anatase and rutile phases showed bacterial killing efficacy over 50% for S. sanguinis and over 80% for MRSA after UVA or UVC treatments. Finally, two forming voltage sample groups in two of the electrolytes were examined for MC3T3E-1 cell attachment, proliferation, and differentiation. Total intracellular protein content, alkaline phosphatase (ALP) activity, osteocalcin (OCN) activity, and cellular mineralization were investigated for different time periods up to 21 days. All sample groups showed suitable cellular proliferation, differentiation, and maturation but those anodized in the phosphoric acid containing electrolyte showed delayed proliferation and early differentiation and maturation. Also, anodized samples containing at least 50% anatase were shown to produce higher osteoblast mineralization compared to majority rutile phase anodized layers.

Gastrointestinal cell lines form polarized epithelia with an adherent mucus layer when cultured in semi-wet interfaces with mechanical stimulation.

PubMed

Navabi, Nazanin; McGuckin, Michael A; Lindén, Sara K

2013-01-01

Mucin glycoproteins are secreted in large quantities by mucosal epithelia and cell surface mucins are a prominent feature of the glycocalyx of all mucosal epithelia. Currently, studies investigating the gastrointestinal mucosal barrier use either animal experiments or non-in vivo like cell cultures. Many pathogens cause different pathology in mice compared to humans and the in vitro cell cultures used are suboptimal because they are very different from an in vivo mucosal surface, are often not polarized, lack important components of the glycocalyx, and often lack the mucus layer. Although gastrointestinal cell lines exist that produce mucins or polarize, human cell line models that reproducibly create the combination of a polarized epithelial cell layer, functional tight junctions and an adherent mucus layer have been missing until now. We trialed a range of treatments to induce polarization, 3D-organization, tight junctions, mucin production, mucus secretion, and formation of an adherent mucus layer that can be carried out using standard equipment. These treatments were tested on cell lines of intestinal (Caco-2, LS513, HT29, T84, LS174T, HT29 MTX-P8 and HT29 MTX-E12) and gastric (MKN7, MKN45, AGS, NCI-N87 and its hTERT Clone5 and Clone6) origins using Ussing chamber methodology and (immuno)histology. Semi-wet interface culture in combination with mechanical stimulation and DAPT caused HT29 MTX-P8, HT29 MTX-E12 and LS513 cells to polarize, form functional tight junctions, a three-dimensional architecture resembling colonic crypts, and produce an adherent mucus layer. Caco-2 and T84 cells also polarized, formed functional tight junctions and produced a thin adherent mucus layer after this treatment, but with less consistency. In conclusion, culture methods affect cell lines differently, and testing a matrix of methods vs. cell lines may be important to develop better in vitro models. The methods developed herein create in vitro mucosal surfaces suitable for studies of host-pathogen interactions at the mucosal surface.

Gastrointestinal Cell Lines Form Polarized Epithelia with an Adherent Mucus Layer when Cultured in Semi-Wet Interfaces with Mechanical Stimulation

PubMed Central

Navabi, Nazanin; McGuckin, Michael A.; Lindén, Sara K.

2013-01-01

Mucin glycoproteins are secreted in large quantities by mucosal epithelia and cell surface mucins are a prominent feature of the glycocalyx of all mucosal epithelia. Currently, studies investigating the gastrointestinal mucosal barrier use either animal experiments or non-in vivo like cell cultures. Many pathogens cause different pathology in mice compared to humans and the in vitro cell cultures used are suboptimal because they are very different from an in vivo mucosal surface, are often not polarized, lack important components of the glycocalyx, and often lack the mucus layer. Although gastrointestinal cell lines exist that produce mucins or polarize, human cell line models that reproducibly create the combination of a polarized epithelial cell layer, functional tight junctions and an adherent mucus layer have been missing until now. We trialed a range of treatments to induce polarization, 3D-organization, tight junctions, mucin production, mucus secretion, and formation of an adherent mucus layer that can be carried out using standard equipment. These treatments were tested on cell lines of intestinal (Caco-2, LS513, HT29, T84, LS174T, HT29 MTX-P8 and HT29 MTX-E12) and gastric (MKN7, MKN45, AGS, NCI-N87 and its hTERT Clone5 and Clone6) origins using Ussing chamber methodology and (immuno)histology. Semi-wet interface culture in combination with mechanical stimulation and DAPT caused HT29 MTX-P8, HT29 MTX-E12 and LS513 cells to polarize, form functional tight junctions, a three-dimensional architecture resembling colonic crypts, and produce an adherent mucus layer. Caco-2 and T84 cells also polarized, formed functional tight junctions and produced a thin adherent mucus layer after this treatment, but with less consistency. In conclusion, culture methods affect cell lines differently, and testing a matrix of methods vs. cell lines may be important to develop better in vitro models. The methods developed herein create in vitro mucosal surfaces suitable for studies of host-pathogen interactions at the mucosal surface. PMID:23869232

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Lehao

A nanocrystalline surface layer was produced on Mg-3 wt.% Li-6 wt.% Al alloy by means of surface mechanical attrition treatment (SMAT). Microstructure features of various sections were systematically characterized by transmission electron microscopy. The results indicate that grain refinement induced by SMAT is dominated mainly by dislocation slip. Twinning is active at the early stage of grain refinement process when the grain size is large. The dislocation-dominated deformation mechanism is attributed to the change of c/a ratio due to the alloying of Li in Mg matrix and the suppression of twinning due to grain refinement. Nanoindentation results show that themore » hardness of the surface is enhanced by SMAT. - Highlights: •Nanocrystalline surface layer was produced on Mg-3 wt.%Li-6 wt.%Al alloy by SMAT. •Grain refinement induced by SMAT is dominated mainly by dislocation slip. •Twinning is active at the early stage of grain refinement process. •The hardness of the surface was enhanced by SMAT.« less

Improved high-temperature silicide coatings

NASA Technical Reports Server (NTRS)

Klopp, W. D.; Stephens, J. R.; Stetson, A. R.; Wimber, R. T.

1969-01-01

Special technique for applying silicide coatings to refractory metal alloys improves their high-temperature protective capability. Refractory metal powders mixed with a baked-out organic binder and sintered in a vacuum produces a porous alloy layer on the surface. Exposing the layer to hot silicon converts it to a silicide.

Bioassembled layered silicate-metal nanoparticle hybrids.

PubMed

Drummy, Lawrence F; Jones, Sharon E; Pandey, Ras B; Farmer, B L; Vaia, Richard A; Naik, Rajesh R

2010-05-01

Here we report on the bioenabled assembly of layered nanohybrids using peptides identified with regard to their affinity to the nanoparticle surface. A dodecamer peptide termed M1, determined from a phage peptide display library, was found to bind to the surface of a layered aluminosilicate (montmorillonite, MMT). Fusion of a metal binding domain to the M1 peptide or the M1 peptide by itself was able to direct the growth of metal nanoparticles, such as gold and cobalt-platinum, respectively, on the MMT. This method of producing hybrid nanoclay materials will have utility in catalytic, optical, biomedical, and composite materials applications.

Homogeneous near surface activity distribution by double energy activation for TLA

NASA Astrophysics Data System (ADS)

Takács, S.; Ditrói, F.; Tárkányi, F.

2007-10-01

Thin layer activation (TLA) is a versatile tool for activating thin surface layers in order to study real-time the surface loss by wear, corrosion or erosion processes of the activated parts, without disassembling or stopping running mechanical structures or equipment. The research problem is the determination of the irradiation parameters to produce point-like or large area optimal activity-depth distribution in the sample. Different activity-depth profiles can be produced depending on the type of the investigated material and the nuclear reaction used. To produce activity that is independent of the depth up to a certain depth is desirable when the material removed from the surface by wear, corrosion or erosion can be collected completely. By applying dual energy irradiation the thickness of this quasi-constant activity layer can be increased or the deviation of the activity distribution from a constant value can be minimized. In the main, parts made of metals and alloys are suitable for direct activation, but by using secondary particle implantation the wear of other materials can also be studied in a surface range a few micrometers thick. In most practical cases activation of a point-like spot (several mm2) is enough to monitor the wear, corrosion or erosion, but for special problems relatively large surfaces areas of complicated spatial geometry need to be activated uniformly. Two ways are available for fulfilling this task, (1) production of large area beam spot or scanning the beam over the surface in question from the accelerator side, or (2) a programmed 3D movement of the sample from the target side. Taking into account the large variability of tasks occurring in practice, the latter method was chosen as the routine solution in our cyclotron laboratory.

Chain polymerization of diacetylene compound multilayer films on the topmost surface initiated by a scanning tunneling microscope tip.

PubMed

Takajo, Daisuke; Okawa, Yuji; Hasegawa, Tsuyoshi; Aono, Masakazu

2007-05-08

Chain polymerizations of diacetylene compound multilayer films on graphite substrates were examined with a scanning tunneling microscope (STM) at the liquid/solid interface of the phenyloctane solution. The first layer grew very quickly into many small domains. This was followed by the slow formation of the piled up layers into much larger domains. Chain polymerization on the topmost surface layer could be initiated by applying a pulsed voltage between the STM tip and the substrate, usually producing a long polymer of submicrometer length. In contrast, polymerizations on the underlying layer were never observed. This can be explained by a conformation model in which the polymer backbone is lifted up.

Process for the Production of Star Tracklng [Tracking] Reticles

NASA Technical Reports Server (NTRS)

Smith, Wade O. (Inventor); Toft, Albert R. (Inventor)

1972-01-01

A method for the production of reticles, particularly those for use in outer space, wherein the product is a quartz base coated with highly adherent layers of chromium, chromium-silver, and silver vacuum deposited through a mask, and then coated with an electrodeposit of copper from a copper sulfate solution followed by an electrodeposit of black chromium. The masks are produced by coating a beryllium-copper alloy substrate with a positive working photoresist, developing the photoresist according to a pattern to leave a positive mask, plating uncoated areas with gold, removing the photoresist, coating the substrate with a negative working photoresist, developing the negative working photoresist to expose the base metal of the pattern, and chemically etching the unplated side of the pattern to produce the mask. The mask produced is then used in the vacuum deposition of: (1) chromium metal on the surface of a quartz base to obtain a highly adherent quartz-chromium interface; (2) silver on the chromium deposit, during the final stage of chromium deposit, to produce a silver chromium alloy layer; and (3) silver onto the surface of the alloy layer. The coated quartz base is then coated by electroplating utilizing an acid copper deposit followed by a black chromium electrodeposit to produce the product of the present invention.

Process reduces pore diameters to produce superior filters

NASA Technical Reports Server (NTRS)

Todd, H. H.

1966-01-01

Porous metal structure with very small pore diameters is produced by heating the structure in oxygen for an oxidized surface layer, cooling it, and heating it in hydrogen to deoxidize the oxidized portion. Such structures are superior catalyst beds and filters.

Abrasion and deformed layer formation of manganese-zinc ferrite in sliding contact with lapping tapes

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Buckley, D. H.; Tanaka, K.

1986-01-01

Wear experiments were conducted using replication electron microscopy and reflection electron diffraction to study abrasion and the deformed layers produced in single-crystal Mn-Zn ferrite simulated heads during contact with lapping tapes. The crystaline state of the head is changed drastically during the abrasion process. Crystalline states ranging from nearly amorphous to highly textured polycrystalline can be produced on the wear surface of a single-crystal Mn-Zn ferrite head. The total thickness of the deformed layer was approximately 0.8 microns. This thickness increased as the load and abrasive grit size increased. The anisotropic wear of the ferrite was found to be inversely proportional to the hardness of the wear surface. The wear was lower in the order 211 111 10 0110. The wear of the ferrite increased markedly with an increase in sliding velocity and abrasive grit size.

Corrosion resistance and biological activity of TiO2 implant coatings produced in oxygen-rich environments.

PubMed

Zhang, Rui; Wan, Yi; Ai, Xing; Liu, Zhanqiang; Zhang, Dong

2017-01-01

The physical and chemical properties of bio-titanium alloy implant surfaces play an important role in their corrosion resistance and biological activity. New turning and turning-rolling processes are presented, employing an oxygen-rich environment in order to obtain titanium dioxide layers that can both protect implants from corrosion and also promote cell adhesion. The surface topographies, surface roughnesses and chemical compositions of the sample surfaces were obtained using scanning electron microscopy, a white light interferometer, and the Auger electron spectroscopy, respectively. The corrosion resistance of the samples in a simulated body fluid was determined using electrochemical testing. Biological activity on the samples was also analyzed, using a vitro cell culture system. The results show that compared with titanium oxide layers formed using a turning process in air, the thickness of the titanium oxide layers formed using turning and turning-rolling processes in an oxygen-rich environment increased by 4.6 and 7.3 times, respectively. Using an oxygen-rich atmosphere in the rolling process greatly improves the corrosion resistance of the resulting samples in a simulated body fluid. On samples produced using the turning-rolling process, cells spread quickly and exhibited the best adhesion characteristics.

Surface waves on a soft viscoelastic layer produced by an oscillating microbubble.

PubMed

Tinguely, Marc; Hennessy, Matthew G; Pommella, Angelo; Matar, Omar K; Garbin, Valeria

2016-05-14

Ultrasound-driven bubbles can cause significant deformation of soft viscoelastic layers, for instance in surface cleaning and biomedical applications. The effect of the viscoelastic properties of a boundary on the bubble-boundary interaction has been explored only qualitatively, and remains poorly understood. We investigate the dynamic deformation of a viscoelastic layer induced by the volumetric oscillations of an ultrasound-driven microbubble. High-speed video microscopy is used to observe the deformation produced by a bubble oscillating at 17-20 kHz in contact with the surface of a hydrogel. The localised oscillating pressure applied by the bubble generates surface elastic (Rayleigh) waves on the gel, characterised by elliptical particle trajectories. The tilt angle of the elliptical trajectories varies with increasing distance from the bubble. Unexpectedly, the direction of rotation of the surface elements on the elliptical trajectories shifts from prograde to retrograde at a distance from the bubble that depends on the viscoelastic properties of the gel. To explain these behaviours, we develop a simple three-dimensional model for the deformation of a viscoelastic solid by a localised oscillating force. By using as input for the model the values of the shear modulus obtained from the propagation velocity of the Rayleigh waves, we find good qualitative agreement with the experimental observations.

Assessment of a 3-D boundary layer code to predict heat transfer and flow losses in a turbine

NASA Technical Reports Server (NTRS)

Anderson, O. L.

1984-01-01

Zonal concepts are utilized to delineate regions of application of three-dimensional boundary layer (DBL) theory. The zonal approach requires three distinct analyses. A modified version of the 3-DBL code named TABLET is used to analyze the boundary layer flow. This modified code solves the finite difference form of the compressible 3-DBL equations in a nonorthogonal surface coordinate system which includes coriolis forces produced by coordinate rotation. These equations are solved using an efficient, implicit, fully coupled finite difference procedure. The nonorthogonal surface coordinate system is calculated using a general analysis based on the transfinite mapping of Gordon which is valid for any arbitrary surface. Experimental data is used to determine the boundary layer edge conditions. The boundary layer edge conditions are determined by integrating the boundary layer edge equations, which are the Euler equations at the edge of the boundary layer, using the known experimental wall pressure distribution. Starting solutions along the inflow boundaries are estimated by solving the appropriate limiting form of the 3-DBL equations.

Semiconductor light-emitting devices having concave microstructures providing improved light extraction efficiency and method for producing same

DOEpatents

Tansu, Nelson; Gilchrist, James F; Ee, Yik-Khoon; Kumnorkaew, Pisist

2013-11-19

A conventional semiconductor LED is modified to include a microlens layer over its light-emitting surface. The LED may have an active layer including at least one quantum well layer of InGaN and GaN. The microlens layer includes a plurality of concave microstructures that cause light rays emanating from the LED to diffuse outwardly, leading to an increase in the light extraction efficiency of the LED. The concave microstructures may be arranged in a substantially uniform array, such as a close-packed hexagonal array. The microlens layer is preferably constructed of curable material, such as polydimethylsiloxane (PDMS), and is formed by soft-lithography imprinting by contacting fluid material of the microlens layer with a template bearing a monolayer of homogeneous microsphere crystals, to cause concave impressions, and then curing the material to fix the concave microstructures in the microlens layer and provide relatively uniform surface roughness.

Growth of delta-doped layers on silicon CCD/S for enhanced ultraviolet response

NASA Technical Reports Server (NTRS)

Hoenk, Michael E. (Inventor); Grunthaner, Paula J. (Inventor); Grunthaner, Frank J. (Inventor); Terhune, Robert W. (Inventor); Hecht, Michael H. (Inventor)

1994-01-01

The backside surface potential well of a backside-illuminated CCD is confined to within about half a nanometer of the surface by using molecular beam epitaxy (MBE) to grow a delta-doped silicon layer on the back surface. Delta-doping in an MBE process is achieved by temporarily interrupting the evaporated silicon source during MBE growth without interrupting the evaporated p+ dopant source (e.g., boron). This produces an extremely sharp dopant profile in which the dopant is confined to only a few atomic layers, creating an electric field high enough to confine the backside surface potential well to within half a nanometer of the surface. Because the probability of UV-generated electrons being trapped by such a narrow potential well is low, the internal quantum efficiency of the CCD is nearly 100% throughout the UV wavelength range. Furthermore, the quantum efficiency is quite stable.

Lead Acetate Based Hybrid Perovskite Through Hot Casting for Planar Heterojunction Solar Cells

NASA Astrophysics Data System (ADS)

Shin, Gwang Su; Choi, Won-Gyu; Na, Sungjae; Gökdemir, Fatma Pinar; Moon, Taeho

2018-03-01

Flawless coverage of a perovskite layer is essential in order to achieve realistic high-performance planar heterojunction solar cells. We present that high-quality perovskite layers can be efficiently formed by a novel hot casting route combined with MAI (CH3NH3I) and non-halide lead acetate (PbAc2) precursors under ambient atmosphere. Casting temperature is controlled to produce various perovskite microstructures and the resulted crystalline layers are found to be comprised of closely packed islands with a smooth surface structure. Lead acetate employed perovskite solar cells are fabricated using PEDOT:PSS and PCBM charge transporting layers, in p- i- n type planar architecture. Especially, the outstanding open-circuit voltage demonstrates the high crystallinity and dense coverage of the produced perovskite layers by this facile route.

Fabrication of hierarchical hybrid structures using bio-enabled layer-by-layer self-assembly.

PubMed

Hnilova, Marketa; Karaca, Banu Taktak; Park, James; Jia, Carol; Wilson, Brandon R; Sarikaya, Mehmet; Tamerler, Candan

2012-05-01

Development of versatile and flexible assembly systems for fabrication of functional hybrid nanomaterials with well-defined hierarchical and spatial organization is of a significant importance in practical nanobiotechnology applications. Here we demonstrate a bio-enabled self-assembly technique for fabrication of multi-layered protein and nanometallic assemblies utilizing a modular gold-binding (AuBP1) fusion tag. To accomplish the bottom-up assembly we first genetically fused the AuBP1 peptide sequence to the C'-terminus of maltose-binding protein (MBP) using two different linkers to produce MBP-AuBP1 hetero-functional constructs. Using various spectroscopic techniques, surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR), we verified the exceptional binding and self-assembly characteristics of AuBP1 peptide. The AuBP1 peptide tag can direct the organization of recombinant MBP protein on various gold surfaces through an efficient control of the organic-inorganic interface at the molecular level. Furthermore using a combination of soft-lithography, self-assembly techniques and advanced AuBP1 peptide tag technology, we produced spatially and hierarchically controlled protein multi-layered assemblies on gold nanoparticle arrays with high molecular packing density and pattering efficiency in simple, reproducible steps. This model system offers layer-by-layer assembly capability based on specific AuBP1 peptide tag and constitutes novel biological routes for biofabrication of various protein arrays, plasmon-active nanometallic assemblies and devices with controlled organization, packing density and architecture. Copyright © 2011 Wiley Periodicals, Inc.

Fabrication of super slippery sheet-layered and porous anodic aluminium oxide surfaces and its anticorrosion property

NASA Astrophysics Data System (ADS)

Song, Tingting; Liu, Qi; Liu, Jingyuan; Yang, Wanlu; Chen, Rongrong; Jing, Xiaoyan; Takahashi, Kazunobu; Wang, Jun

2015-11-01

Inspired by natural plants such as Nepenthes pitcher plants, super slippery surfaces have been developed to improve the attributes of repellent surfaces. In this report, super slippery porous anodic aluminium oxide (AAO) surfaces have fabricated by a simple and reproducible method. Firstly, the aluminium substrates were treated by an anodic process producing micro-nano structured sheet-layered pores, and then immersed in Methyl Silicone Oil, Fluororalkylsilane (FAS) and DuPont Krytox, respectively, generating super slippery surfaces. Such a good material with excellent anti-corrosion property through a simple and repeatable method may be potential candidates for metallic application in anti-corrosion and extreme environment.

Enhanced thermal shock resistance of ceramics through biomimetically inspired nanofins.

PubMed

Song, Fan; Meng, Songhe; Xu, Xianghong; Shao, Yingfeng

2010-03-26

We propose here a new method to make ceramics insensitive to thermal shock up to their melting temperature. In this method the surface of ceramics was biomimetically roughened into nanofinned surface that creates a thin air layer enveloping the surface of the ceramics during quenching. This air layer increases the heat transfer resistance of the surface of the ceramics by about 10,000 times so that the strong thermal gradient and stresses produced by the steep temperature difference in thermal shock did not occur both on the actual surface and in the interior of the ceramics. This method effectively extends the applications of existing ceramics in the extreme thermal environments.

Applications of Functional Amyloids from Fungi: Surface Modification by Class I Hydrophobins.

PubMed

Piscitelli, Alessandra; Cicatiello, Paola; Gravagnuolo, Alfredo Maria; Sorrentino, Ilaria; Pezzella, Cinzia; Giardina, Paola

2017-06-26

Class I hydrophobins produced from fungi are amongst the first proteins recognized as functional amyloids. They are amphiphilic proteins involved in the formation of aerial structures such as spores or fruiting bodies. They form chemically robust layers which can only be dissolved in strong acids. These layers adhere to different surfaces, changing their wettability, and allow the binding of other proteins. Herein, the modification of diverse types of surfaces with Class I hydrophobins is reported, highlighting the applications of the coated surfaces. Indeed, these coatings can be exploited in several fields, spanning from biomedical to industrial applications, which include biosensing and textile manufacturing.

Fabricating solid carbon porous electrodes from powders

DOEpatents

Kaschmitter, James L.; Tran, Tri D.; Feikert, John H.; Mayer, Steven T.

1997-01-01

Fabrication of conductive solid porous carbon electrodes for use in batteries, double layer capacitors, fuel cells, capacitive dionization, and waste treatment. Electrodes fabricated from low surface area (<50 m.sup.2 /gm) graphite and cokes exhibit excellent reversible lithium intercalation characteristics, making them ideal for use as anodes in high voltage lithium insertion (lithium-ion) batteries. Electrodes having a higher surface area, fabricated from powdered carbon blacks, such as carbon aerogel powder, carbon aerogel microspheres, activated carbons, etc. yield high conductivity carbon compositives with excellent double layer capacity, and can be used in double layer capacitors, or for capacitive deionization and/or waste treatment of liquid streams. By adding metallic catalysts to be high surface area carbons, fuel cell electrodes can be produced.

Fabricating solid carbon porous electrodes from powders

DOEpatents

Kaschmitter, J.L.; Tran, T.D.; Feikert, J.H.; Mayer, S.T.

1997-06-10

Fabrication is described for conductive solid porous carbon electrodes for use in batteries, double layer capacitors, fuel cells, capacitive deionization, and waste treatment. Electrodes fabricated from low surface area (<50 m{sup 2}/gm) graphite and cokes exhibit excellent reversible lithium intercalation characteristics, making them ideal for use as anodes in high voltage lithium insertion (lithium-ion) batteries. Electrodes having a higher surface area, fabricated from powdered carbon blacks, such as carbon aerogel powder, carbon aerogel microspheres, activated carbons, etc. yield high conductivity carbon composites with excellent double layer capacity, and can be used in double layer capacitors, or for capacitive deionization and/or waste treatment of liquid streams. By adding metallic catalysts to high surface area carbons, fuel cell electrodes can be produced. 1 fig.

Experimental measurements of unsteady turbulent boundary layers near separation

NASA Technical Reports Server (NTRS)

Simpson, R. L.

1982-01-01

Investigations conducted to document the behavior of turbulent boundary layers on flat surfaces that separate due to adverse pressure gradients are reported. Laser and hot wire anemometers measured turbulence and flow structure of a steady free stream separating turbulent boundary layer produced on the flow of a wind tunnel section. The effects of sinusoidal and unsteadiness of the free stream velocity on this separating turbulent boundary layer at a reduced frequency were determined. A friction gage and a thermal tuft were developed and used to measure the surface skin friction and the near wall fraction of time the flow moves downstream for several cases. Abstracts are provided of several articles which discuss the effects of the periodic free stream unsteadiness on the structure or separating turbulent boundary layers.

Displacement field for an edge dislocation in a layered half-space

USGS Publications Warehouse

Savage, J.C.

1998-01-01

The displacement field for an edge dislocation in an Earth model consisting of a layer welded to a half-space of different material is found in the form of a Fourier integral following the method given by Weeks et al. [1968]. There are four elementary solutions to be considered: the dislocation is either in the half-space or the layer and the Burgers vector is either parallel or perpendicular to the layer. A general two-dimensional solution for a dip-slip faulting or dike injection (arbitrary dip) can be constructed from a superposition of these elementary solutions. Surface deformations have been calculated for an edge dislocation located at the interface with Burgers vector inclined 0??, 30??, 60??, and 90?? to the interface for the case where the rigidity of the layer is half of that of the half-space and the Poisson ratios are the same. Those displacement fields have been compared to the displacement fields generated by similarly situated edge dislocations in a uniform half-space. The surface displacement field produced by the edge dislocation in the layered half-space is very similar to that produced by an edge dislocation at a different depth in a uniform half-space. In general, a low-modulus (high-modulus) layer causes the half-space equivalent dislocation to appear shallower (deeper) than the actual dislocation in the layered half-space.

Nanostructured GaAs solar cells via metal-assisted chemical etching of emitter layers.

PubMed

Song, Yunwon; Choi, Keorock; Jun, Dong-Hwan; Oh, Jungwoo

2017-10-02

GaAs solar cells with nanostructured emitter layers were fabricated via metal-assisted chemical etching. Au nanoparticles produced via thermal treatment of Au thin films were used as etch catalysts to texture an emitter surface with nanohole structures. Epi-wafers with emitter layers 0.5, 1.0, and 1.5 um in thickness were directly textured and a window layer removal process was performed before metal catalyst deposition. A nanohole-textured emitter layer provides effective light trapping capabilities, reducing the surface reflection of a textured solar cell by 11.0%. However, because the nanostructures have high surface area to volume ratios and large numbers of defects, various photovoltaic properties were diminished by high recombination losses. Thus, we have studied the application of nanohole structures to GaAs emitter solar cells and investigated the cells' antireflection and photovoltaic properties as a function of the nanohole structure and emitter thickness. Due to decreased surface reflection and improved shunt resistance, the solar cell efficiency increased from 4.25% for non-textured solar cells to 7.15% for solar cells textured for 5 min.

Instabilities of thin layers of conducting fluids produced by time dependent magnetic fields

NASA Astrophysics Data System (ADS)

Burguete, Javier

2011-11-01

We present the recent results of an experiment where thin layers of conducting fluids are forced by time-dependent magnetic fields perpendicular to their surface. We use as conducting fluid an In-Ga-Sn alloy, immersed in a 5% hydrocloric acid solution to prevent oxidation. The conducting layers have a circular shape, and are placed inside a set-up that produces the vertical magnetic field. Due to MHD effects, the competition between the Lorentz force and gravity triggers an instability of the free surface. The shape of this surface can adopt many different configurations, with a very rich dynamics, presenting azimuthal wave numbers between 3 and 8 for the explored parameters. The magnetic field evolves harmonically with a frequency up to 10Hz, small enough to not to observe skin depth effects and with a magnitude up to 0.1 T. Different resonant regions have been observed, for narrow windows of the forcing frequency. We have analysed the existence of thresholds for these instabilities, depending on the wave number and experimental parameters. These results are compared with others present in the literature.

Effect of abrasive grit size on wear of manganese-zinc ferrite under three-body abrasion

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

1987-01-01

Wear experiments were conducted using replication electron microscopy and reflection electron diffraction to study abrasion and deformed layers produced in single-crystal Mn-Zn ferrites under three-body abrasion. The abrasion mechanism of Mn-Zn ferrite changes drastically with the size of abrasive grits. With 15-micron (1000-mesh) SiC grits, abrasion of Mn-Zn ferrite is due principally to brittle fracture; while with 4- and 2-micron (4000- and 6000-mesh) SiC grits, abrasion is due to plastic deformation and fracture. Both microcracking and plastic flow produce polycrystalline states on the wear surfaces of single-crystal Mn-Zn ferrites. Coefficient of wear, total thickness of the deformed layers, and surface roughness of the wear surfaces increase markedly with an increase in abrasive grit size. The total thicknesses of the deformed layers are 3 microns for the ferrite abraded by 15-micron SiC, 0.9 microns for the ferrite abraded by 4-micron SiC, and 0.8 microns for the ferrite abraded by 1-micron SiC.

Method of producing nanopatterned articles using surface-reconstructed block copolymer films

DOEpatents

Russell, Thomas P; Park, Soojin; Wang, Jia-Yu; Kim, Bokyung

2013-08-27

Nanopatterned surfaces are prepared by a method that includes forming a block copolymer film on a substrate, annealing and surface reconstructing the block copolymer film to create an array of cylindrical voids, depositing a metal on the surface-reconstructed block copolymer film, and heating the metal-coated block copolymer film to redistribute at least some of the metal into the cylindrical voids. When very thin metal layers and low heating temperatures are used, metal nanodots can be formed. When thicker metal layers and higher heating temperatures are used, the resulting metal structure includes nanoring-shaped voids. The nanopatterned surfaces can be transferred to the underlying substrates via etching, or used to prepare nanodot- or nanoring-decorated substrate surfaces.

Laser-assisted electrochemical micromachining of mould cavity on the stainless steel surface

NASA Astrophysics Data System (ADS)

Li, Xiaohai; Wang, Shuming; Wang, Dong; Tong, Han

2018-02-01

In order to fabricate the micro mould cavities with complex structures on 304 stainless steel, laser-assisted electrochemical micromachining (EMM) based on surface modification by fiber laser masking was studied,and a new device of laser-assisted EMM was developed. Laser marking on the surface of 304 stainless steel can first be realized by fiber laser heating scanning. Through analysis of X ray diffraction analysis (XRD), metal oxide layer with predefined pattern can be formed by laser marking, and phase transformation can also occur on the 304 stainless steel surface, which produce the laser masking layer with corrosion resistance. The stainless steel surface with laser masking layer is subsequently etched by EMM, the laser masking layer severs as the temporary protective layer without relying on lithography mask, the fabrication of formed electrodes is also avoided, so micro pattern cavities can fast be fabricated. The impacts on machining accuracy during EMM with laser masking were discussed to optimize machining parameters, such as machining voltage, electrolyte concentration, duty cycle of pulse power supply and electrode gap size, the typical mould cavities 23μm deep were fabricated under the optimized parameters.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donald, Scott B.; Siekhaus, Wigbert J.; Nelson, Art J.

X-ray photoelectron spectroscopy in combination with secondary ion mass spectrometry depth profiling were used to investigate the surface and interfacial chemistry of C + ion implanted polycrystalline uranium subsequently oxidized in air for over 10 years at ambient temperature. The original implantation of 33 keV C + ions into U 238 with a dose of 4.3 × 10 17 cm –3 produced a physically and chemically modified surface layer that was characterized and shown to initially prevent air oxidation and corrosion of the uranium after 1 year in air at ambient temperature. The aging of the surface and interfacial layersmore » were examined by using the chemical shift of the U 4f, C 1s, and O 1s photoelectron lines. In addition, valence band spectra were used to explore the electronic structure of the aged carbide surface and interface layer. Moreover, the time-of-flight secondary ion mass spectrometry depth profiling results for the aged sample confirmed an oxidized uranium carbide layer over the carbide layer/U metal interface.« less

Influence of Near-Surface Severe Plastic Deformation of Mild Steel on the Inhibition Performance of Sodium Molybdate and 1H-Benzotriazole in Artificial Sea Water

NASA Astrophysics Data System (ADS)

Sabet Bokati, Kazem; Dehghanian, Changiz; Babaei, Mahdi

2018-02-01

The effects of near-surface severe plastic deformation (NS-SPD) on the inhibition performance of sodium molybdate (SM) and 1H-benzotriazole (BTA) for mild steel were investigated using weight loss, polarization and electrochemical impedance spectroscopy measurements. The crystal grain size of NS-SPD-processed surface was analyzed by x-ray diffractometry and field emission scanning electron microscopy. A deformed layer with thickness of 20 ± 5 µm was produced on mild steel surface after NS-SPD process due to accumulated strains. The NS-SPD process caused more effective adsorption of corrosion inhibitors due to the fabrication of a surface with a high density of preferential adsorption sites. However, the stability of protective layer was predominantly influenced by the effect of NS-SPD process on inhibition efficiency. The fairly good persistence of protective layer formed on the surface by SM-containing solution and also positive effect of NS-SPD process on adsorption of molybdate ions caused higher inhibition performance for sodium molybdate. However, NS-SPD process encouraged deterioration of protective layer formed on steel surface in the presence of BTA inhibitor. It was ascribed to partial coverage of surface, low stability of adsorbed layer and thus more adsorption of aggressive ions on unprotected area which was uncovered during immersion time.

Surface acoustic waves in one-dimensional piezoelectric-metallic phononic crystal: Effect of a cap layer.

PubMed

Alami, M; El Boudouti, E H; Djafari-Rouhani, B; El Hassouani, Y; Talbi, A

2018-06-18

We study the propagation of transverse acoustic waves associated with the surface of a semi-infinite superlattice (SL) composed of piezoelectric-metallic layers and capped with a piezoelectric layer. We present closed-form expressions for localized surface waves, the so-called Bleustein-Gulyaev (BG) waves depending on whether the cap layer is open-circuited or short-circuited. These expressions are obtained by means of the Green's function method which enables to deduce also the densities of states. These theoretical results are illustrated by a few numerical applications to SLs made of piezoelectric layers of hexagonal symmetry belonging to the 6 mm class such as PZT4 and ZnO in contact with metallic layers such as Fe, Al, Au, Cu and boron-doped-diamond. We demonstrate a rule about the existence of surface modes when considering two complementary semi-infinite SLs obtained by the cleavage of an infinite SL along a plane parallel to the piezoelectric layers. Indeed, when the surface layers are open-circuited, one obtains one surface mode per gap, this mode is associated with one of the two complementary SLs. However, when the surface layers are short-circuited, this rule is not fulfilled and one can obtain zero, one or two modes inside each gap of the two complementary SLs depending on the position of the plane where the cleavage is produced. We show that in addition to the BG surface waves localized at the surface of the cap layer, there may exist true guided waves and pseudo-guided waves (i.e. leaky waves) induced by the cap layer either inside the gaps or inside the bands of the SL respectively. Also, we highlight the possibility of existence of interface modes between the SL and a cap layer as well as an interaction between these modes and the BG surface mode when both modes fall in the same band gaps of the SL. The strength of the interaction depends on the width of the cap layer. Finally, we show that the electromechanical coupling coefficient (ECC) is very sensitive to the cap layer thickness, in particular we calculate and discuss the behavior of the ECC as a function of the adlayer thickness for the low velocity surface modes of the SL which exhibit the highest ECC values. The effect of the nature of the metallic layers inside the SL on the ECC is also investigated. The different surface modes discussed in this work should have applications in sensing applications. Copyright © 2018. Published by Elsevier B.V.

Influences of Ocean Thermohaline Stratification on Arctic Sea Ice

NASA Astrophysics Data System (ADS)

Toole, J. M.; Timmermans, M.-L.; Perovich, D. K.; Krishfield, R. A.; Proshutinsky, A.; Richter-Menge, J. A.

2009-04-01

The Arctic Ocean's surface mixed layer constitutes the dynamical and thermodynamical link between the sea ice and the underlying waters. Wind stress, acting directly on the surface mixed layer or via wind-forced ice motion, produce surface currents that can in turn drive deep ocean flow. Mixed layer temperature is intimately related to basal sea ice growth and melting. Heat fluxes into or out of the surface mixed layer can occur at both its upper and lower interfaces: the former via air-sea exchange at leads and conduction through the ice, the latter via turbulent mixing and entrainment at the layer base. Variations in Arctic Ocean mixed layer properties are documented based on more than 16,000 temperature and salinity profiles acquired by Ice-Tethered Profilers since summer 2004 and analyzed in conjunction with sea ice observations from Ice Mass Balance Buoys and atmospheric heat flux estimates. Guidance interpreting the observations is provided by a one-dimensional ocean mixed layer model. The study focuses attention on the very strong density stratification about the mixed layer base in the Arctic that, in regions of sea ice melting, is increasing with time. The intense stratification greatly impedes mixed layer deepening by vertical convection and shear mixing, and thus limits the flux of deep ocean heat to the surface that could influence sea ice growth/decay. Consistent with previous work, this study demonstrates that the Arctic sea ice is most sensitive to changes in ocean mixed layer heat resulting from fluxes across its upper (air-sea and/or ice-water) interface.

Microwave-assisted routes for rapid and efficient modification of layered perovskites.

PubMed

Akbarian-Tefaghi, S; Wiley, J B

2018-02-27

Recent advances in exploiting microwave radiation in the topochemical modification of layered oxide perovskites are presented. Such methods work well for rapid bulk synthetic steps used in the production of novel inorganic-organic hybrids (protonation, grafting, intercalation, and in situ click reactions), exfoliation to produce dispersed nanosheets, and post-exfoliation processing to rapidly vary nanosheet surface groups. Compared to traditional methods that often take days, microwave methods can produce quality products in as little as 1-2 h.

Surface texturing of fluoropolymers

NASA Technical Reports Server (NTRS)

Banks, B. A.; Mirtich, M. J.; Sovey, J. S. (Inventor)

1982-01-01

A method is disclosed for improving surface texture for adhesive bonding, metal bonding, substrate plating, decal substrate preparation, and biomedical implant applications. The surface to be bonded is dusted in a controlled fashion to produce a disbursed layer of fine mesh particles which serve as masks. The surface texture is produced by impinging gas ions on the masked surface. The textured surface takes the form of pillars or cones. The bonding material, such as a liquid epoxy, flows between the pillars which results in a bond having increased strength. For bonding metals a thin film of metal is vapor or sputter deposited onto the textured surface. Electroplating or electroless plating is then used to increase the metal thickness in the desired amount.

Design of water-repellant coating using dual scale size of hybrid silica nanoparticles on polymer surface

NASA Astrophysics Data System (ADS)

Conti, J.; De Coninck, J.; Ghazzal, M. N.

2018-04-01

The dual-scale size of the silica nanoparticles is commonly aimed at producing dual-scale roughness, also called hierarchical roughness (Lotus effect). In this study, we describe a method to build a stable water-repellant coating with controlled roughness. Hybrid silica nanoparticles are self-assembled over a polymeric surface by alternating consecutive layers. Each one uses homogenously distributed silica nanoparticles of a particular size. The effect of the nanoparticle size of the first layer on the final roughness of the coating is studied. The first layer enables to adjust the distance between the silica nanoparticles of the upper layer, leading to a tuneable and controlled final roughness. An optimal size nanoparticle has been found for higher water-repellency. Furthermore, the stability of the coating on polymeric surface (Polycarbonate substrate) is ensured by photopolymerization of hybridized silica nanoparticles using Vinyl functional groups.

Largely Enhanced Single-molecule Fluorescence in Plasmonic Nanogaps formed by Hybrid Silver Nanostructures

PubMed Central

Zhang, Jian; Lakowicz, Joseph R.

2013-01-01

It has been suggested that narrow gaps between metallic nanostructures can be practical for producing large field enhancement. We design a hybrid silver nanostructure geometry in which fluorescent emitters are sandwiched between silver nanoparticles and silver island film (SIF). A desired number of polyelectrolyte layers are deposited on the SIF surface before the self-assembly of a second silver nanoparticle layer. Layer-by-layer configuration provides a well-defined dye position. It allows us to study the photophyical behaviors of fluorophores in the resulting gap at the single molecule level. The enhancement factor of a fluorophore located in the gap is much higher than those on silver surfaces alone and on glass. These effects may be used for increased detectability of single molecules bound to surfaces which contain metallic structures for either biophysical studies or high sensitivity assays. PMID:23373787

Titanium bone implants with superimposed micro/nano-scale porosity and antibacterial capability

NASA Astrophysics Data System (ADS)

Necula, B. S.; Apachitei, I.; Fratila-Apachitei, L. E.; van Langelaan, E. J.; Duszczyk, J.

2013-05-01

This study aimed at producing a multifunctional layer with micro/nano-interconnected porosity and antibacterial capability on a rough macro-porous plasma sprayed titanium surface using the plasma electrolytic oxidation process. The layers were electrochemically formed in electrolytes based on calcium acetate and calcium glycerophosphate salts bearing dispersed Ag nanoparticles. They were characterized with respect to surface morphology and chemical composition using a scanning electron microscope equipped with the energy dispersive spectroscopy and back scattering detectors. Scanning electron microscopy images showed the formation of a micro/nano-scale porous layer, comprised of TiO2 bearing Ca and P species and Ag nanoparticles, following accurately the surface topography of the plasma sprayed titanium coating. The Ca/P atomic ratio was found to be close to that of bone apatite. Ag nanoparticles were incorporated on both on top and inside the porous structure of the TiO2 layer.

Cuprous Oxide as a Potential Low-Cost Hole-Transport Material for Stable Perovskite Solar Cells.

PubMed

Nejand, Bahram Abdollahi; Ahmadi, Vahid; Gharibzadeh, Saba; Shahverdi, Hamid Reza

2016-02-08

Inorganic hole-transport materials are commercially desired to decrease the fabrication cost of perovskite solar cells. Here, Cu2O is introduced as a potential hole-transport material for stable, low-cost devices. Considering that Cu2O formation is highly sensitive to the underlying mixture of perovskite precursors and their solvents, we proposed and engineered a technique for reactive magnetron sputtering. The rotational angular deposition of Cu2O yields high surface coverage of the perovskite layer for high rate of charge extraction. Deposition of this Cu2O layer on the pinhole-free perovskite layer produces devices with power conversion efficiency values of up to 8.93%. The engineered Cu2O layers showed uniform, compact, and crack-free surfaces on the perovskite layer without affecting the perovskite structure, which is desired for deposition of the top metal contact and for surface shielding against moisture and mechanical damages. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrasonic measurements of surface defects on flexible circuits using high-frequency focused polymer transducers

NASA Astrophysics Data System (ADS)

Wagle, Sanat; Habib, Anowarul; Melandsø, Frank

2017-07-01

High-frequency transducers made from a layer-by-layer deposition method are investigated as transducers for ultrasonic imaging. Prototypes of adhesive-free transducers with four active elements were made on a high-performance poly(ether imide) substrate with precision milled spherical cavities used to produce focused ultrasonic beams. The transducer prototypes were characterized using a pulse-echo experimental setup in a water tank using a glass plate as a reflector. Then, transducer was used in a three-dimensional ultrasonic scanning tank, to produce high-resolution ultrasonic images of flexible electronic circuits with the aim to detect defects in the outermost cover layer.

Silicon-on Ceramic Process: Silicon Sheet Growth and Device Development for the Large-area Silicon Sheet and Cell Development Tasks of the Low-cost Solar Array Project

NASA Technical Reports Server (NTRS)

Chapman, P. W.; Zook, J. D.; Heaps, J. D.; Grung, B. L.; Koepke, B.; Schuldt, S. B.

1979-01-01

The technical and economic feasibility of producing solar cell-quality silicon was investigated. This was done by coating one surface of carbonized ceramic substrates with a thin layer of large-grain polycrystalline silicon from the melt. Significant progress in the following areas was demonstrated: (1) fabricating a 10 sq cm cell having 9.9 percent conversion efficiency; (2) producing a 225 sq cm layer of sheet silicon; and (3) obtaining 100 microns thick coatings at pull speed of 0.15 cm/sec, although approximately 50 percent of the layer exhibited dendritic growth.

A Study of the Response of Deep Tropical Clouds to Mesoscale Processes. Part 2; Sensitivities to Microphysics, Radiation, and Surface Fluxes

NASA Technical Reports Server (NTRS)

Johnson, Daniel; Tao, Wei-Kuo; Simpson, Joanne

2004-01-01

The Goddard Cumulus Ensemble (GCE) model is used to examine the sensitivities of surface fluxes, explicit radiation, and ice microphysical processes on multi-day simulations of deep tropical convection over the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE). The simulations incorporate large-scale advective temperature and moisture forcing, as well as large-scale momentum, that are updated every time step on a periodic lateral boundary grid. This study shows that when surface fluxes are eliminated, the mean atmosphere is much cooler and drier, convection and CAPE are much weaker, precipitation is less, and cloud coverage in stratiform regions much greater. Surface fluxes using the TOGA COARE flux algorithm are weaker than with the aerodynamic formulation, but closer to the observed fluxes. In addition, similar trends noted above for the case without surface fluxes are produced for the TOGA flux case, albeit to a much lesser extent. The elimination of explicit shortwave and longwave radiation is found to have only minimal effects on the mean thermodynamics, convection, and precipitation. However explicit radiation does have a significant impact on cloud temperatures and structure above 200 mb and on the overall mean vertical circulation. The removal of ice processes produces major changes in the structure of the cloud. Much of the liquid water is transported aloft and into anvils above the melting layer (600 mb), leaving narrow, but intense bands of rainfall in convective regions. The elimination of melting processes leads to greater hydrometeor mass below the melting layer, and produces a much warmer and moister boundary layer, leading to a greater mean CAPE. Finally, the elimination of the graupel species has only a small impact on mean total precipitation, thermodynamics, and dynamics of the simulation, but does produce much greater snow mass just above the melting layer. Some of these results differ from previous CRM studies of tropical systems, which is likely due to the type of simulated system, total time integration, and model setup.

XPS and SIMS study of the surface and interface of aged C + implanted uranium

DOE PAGES

Donald, Scott B.; Siekhaus, Wigbert J.; Nelson, Art J.

2016-09-08

X-ray photoelectron spectroscopy in combination with secondary ion mass spectrometry depth profiling were used to investigate the surface and interfacial chemistry of C + ion implanted polycrystalline uranium subsequently oxidized in air for over 10 years at ambient temperature. The original implantation of 33 keV C + ions into U 238 with a dose of 4.3 × 10 17 cm –3 produced a physically and chemically modified surface layer that was characterized and shown to initially prevent air oxidation and corrosion of the uranium after 1 year in air at ambient temperature. The aging of the surface and interfacial layersmore » were examined by using the chemical shift of the U 4f, C 1s, and O 1s photoelectron lines. In addition, valence band spectra were used to explore the electronic structure of the aged carbide surface and interface layer. Moreover, the time-of-flight secondary ion mass spectrometry depth profiling results for the aged sample confirmed an oxidized uranium carbide layer over the carbide layer/U metal interface.« less

Detection of Nisin and Fibrinogen Adsorption on Poly(ethylene Oxide) Coated Polyurethane Surfaces by Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)

PubMed Central

Schilke, Karl F.; McGuire, Joseph

2011-01-01

Stable, pendant polyethylene oxide (PEO) layers were formed on medical-grade Pellethane® and Tygon® polyurethane surfaces, by adsorption and gamma-irradiation of PEO-polybutadiene-PEO triblock surfactants. Coated and uncoated polyurethanes were challenged individually or sequentially with nisin (a small polypeptide with antimicrobial activity) and/or fibrinogen, and then analyzed with time-of-flight secondary ion mass spectrometry (TOF-SIMS). Data reduction by robust principal components analysis (PCA) allowed detection of outliers, and distinguished adsorbed nisin and fibrinogen. Fibrinogen-contacted surfaces, with or without nisin, were very similar on uncoated polymer surfaces, consistent with nearly complete displacement or coverage of previously-adsorbed nisin by fibrinogen. In contrast, nisin-loaded PEO layers remained essentially unchanged upon challenge with fibrinogen, suggesting that the adsorbed nisin is stabilized within the pendant PEO layer, while the peptide-loaded PEO layer retains its ability to repel large proteins. Coatings of PEO loaded with therapeutic polypeptides on medical polymers have the potential to be used to produce anti-fouling and biofunctional surfaces for implantable or blood-contacting devices. PMID:21440897

Impact toughness of layered VT6 alloy semiproducts

NASA Astrophysics Data System (ADS)

Ganeeva, A. A.; Kruglov, A. A.; Lutfullin, R. Ya.

2010-10-01

Layered semiproducts produced by pressure welding of sheet workpieces of a VT6 titanium alloy are studied. Possible methods of achieving isotropic mechanical properties of the semiproducts are discussed. The pores that are present in solid-phase joint zones are found not to influence the impact toughness of the samples in which layers lie perpendicular to a notch. The fracture surface has a ductile character with certain fracture zones.

Wave phenomena in a high Reynolds number compressible boundary layer

NASA Technical Reports Server (NTRS)

Bayliss, A.; Maestrello, L.; Parikh, P.; Turkel, E.

1985-01-01

Growth of unstable disturbances in a high Reynolds number compressible boundary layer is numerically simulated. Localized periodic surface heating and cooling as a means of active control of these disturbances is studied. It is shown that compressibility in itself stabilizes the flow but at a lower Mach number, significant nonlinear distortions are produced. Phase cancellation is shown to be an effective mechanism for active boundary layer control.

Method for producing chemical energy

DOEpatents

Jorgensen, Betty S.; Danen, Wayne C.

2004-09-21

Fluoroalkylsilane-coated metal particles having a central metal core, a buffer layer surrounding the core, and a fluoroalkylsilane layer attached to the buffer layer are prepared by combining a chemically reactive fluoroalkylsilane compound with an oxide coated metal particle having a hydroxylated surface. The resulting fluoroalkylsilane layer that coats the particles provides them with excellent resistance to aging. The particles can be blended with oxidant particles to form energetic powder that releases chemical energy when the buffer layer is physically disrupted so that the reductant metal core can react with the oxidant.

Atmospheric tides on Venus. III - The planetary boundary layer

NASA Technical Reports Server (NTRS)

Dobrovolskis, A. R.

1983-01-01

Diurnal solar heating of Venus' surface produces variable temperatures, winds, and pressure gradients within a shallow layer at the bottom of the atmosphere. The corresponding asymmetric mass distribution experiences a tidal torque tending to maintain Venus' slow retrograde rotation. It is shown that including viscosity in the boundary layer does not materially affect the balance of torques. On the other hand, friction between the air and ground can reduce the predicted wind speeds from about 5 to about 1 m/sec in the lower atmosphere, more consistent with the observations from Venus landers and descent probes. Implications for aeolian activity on Venus' surface and for future missions are discussed.

Toward the existence of ultrafast diffusion paths in Cu with a gradient microstructure: Room temperature diffusion of Ni

NASA Astrophysics Data System (ADS)

Wang, Z. B.; Lu, K.; Wilde, G.; Divinski, S.

2008-09-01

Room temperature diffusion of Ni63 in Cu with a gradient microstructure prepared by surface mechanical attrition treatment (SMAT) was investigated by applying the radiotracer technique. The results reveal significant penetration of Ni into the nanostructured layer. The relevant diffusivity is higher than that along the conventional high-angle grain boundaries by about six orders of magnitude. This behavior is associated with a higher energy state of internal interfaces produced via plastic deformation. The diffusivity in the top surface layer is somewhat smaller than that in the subsurface layer. This fact is related to nanotwin formation in the former during SMAT.

Boundary-layer exchange by bubble: A novel method for generating transient nanofluidic layers

NASA Astrophysics Data System (ADS)

Jennissen, Herbert P.

2005-10-01

Unstirred layers (i.e., Nernst boundary layers) occur on every dynamic solid-liquid interface, constituting a diffusion barrier, since the velocity of a moving liquid approaches zero at the surface (no slip). If a macromolecule-surface reaction rate is higher than the diffusion rate, the Nernst layer is solute depleted and the reaction rate becomes mass-transport limited. The thickness of a Nernst boundary layer (δN) generally lies between 5 and 50μm. In an evanescent wave rheometer, measuring fibrinogen adsorption to fused silica, we made the fundamental observation that an air bubble preceding the sample through the flow cell abolishes the mass-transport limitation of the Nernst diffusion layer. Instead exponential kinetics are found. Experimental and simulation studies strongly indicate that these results are due to the elimination of the Nernst diffusion layer and its replacement by a dynamic nanofluidic layer (δν) maximally 200-300nm thick. It is suggested that the air bubble leads to a transient boundary-layer separation into a novel nanoboundary layer on the surface and the bulk fluid velocity profile separated by a vortex sheet with an estimated lifetime of 30-60s. A bubble-induced boundary-layer exchange from the Nernst to the nanoboundary layer and back is obtained, giving sufficient time for the measurement of unbiased exponential surface kinetics. Noteworthy is that the nanolayer can exist at all and displays properties such as (i) a long persistence and resistance to dissipation by the bulk liquid (boundary-layer-exchange-hysteresis) and (ii) a lack of solute depletion in spite of boundary-layer separation. The boundary-layer-exchange by bubble (BLEB) method therefore appears ideal for enhancing the rates of all types of diffusion-limited macromolecular reactions on surfaces with contact angles between 0° and 90° and only appears limited by slippage due to nanobubbles or an air gap beneath the nanofluidic layer on very hydrophobic surfaces. The possibility of producing nanoboundary layers without any nanostructuring or nanomachining should also be useful for fundamental physical studies in nanofluidics.

Transient behavior of granular materials with symmetric conditions for tumbler shapes and fill fractions

NASA Astrophysics Data System (ADS)

Pohlman, Nicholas; Si, Yun

2014-11-01

The typical granular motion in circular tumblers is considered steady-state since there are no features to disrupt the top surface layer dimension. In polygon tumblers, however, the flowing layer is perpetually changing length, which creates unsteady conditions with corresponding change in the flow behavior. Prior work showed the minimization of free surface energy is independent of tumbler dimension, particle size, and rotation rate. This subsequent research reports on experiments where dimensional symmetry of the free surface in triangular and square tumblers with varying fill fractions do not necessarily produce the symmetric flow behaviors. Results of the quasi-2D tumbler experiment show that other dimensions aligned with gravity and the instantaneous free surface influence the phase when extrema for angle of repose and other flow features occur. The conclusion is that 50% fill fraction may produce geometric symmetry of dimensions, but the symmetry point of flow likely occurs at a lower fill fraction.

Does the Sverdrup critical depth model explain bloom dynamics in estuaries?

USGS Publications Warehouse

Lucas, L.V.; Cloern, J.E.; Koseff, Jeffrey R.; Monismith, Stephen G.; Thompson, J.K.

1998-01-01

In this paper we use numerical models of coupled biological-hydrodynamic processes to search for general principles of bloom regulation in estuarine waters. We address three questions: what are the dynamics of stratification in coastal systems as influenced by variable freshwater input and tidal stirring? How does phytoplankton growth respond to these dynamics? Can the classical Sverdrup Critical Depth Model (SCDM) be used to predict the timing of bloom events in shallow coastal domains such as estuaries? We present results of simulation experiments which assume that vertical transport and net phytoplankton growth rates are horizontally homogeneous. In the present approach the temporally and spatially varying turbulent diffusivities for various stratification scenarios are calculated using a hydrodynamic code that includes the Mellor-Yamada 2.5 turbulence closure model. These diffusivities are then used in a time- and depth-dependent advection-diffusion equation, incorporating sources and sinks, for the phytoplankton biomass. Our modeling results show that, whereas persistent stratification greatly increases the probability of a bloom, semidiurnal periodic stratification does not increase the likelihood of a phytoplankton bloom over that of a constantly unstratified water column. Thus, for phytoplankton blooms, the physical regime of periodic stratification is closer to complete mixing than to persistent stratification. Furthermore, the details of persistent stratification are important: surface layer depth, thickness of the pycnocline, vertical density difference, and tidal current speed all weigh heavily in producing conditions which promote the onset of phytoplankton blooms. Our model results for shallow tidal systems do not conform to the classical concepts of stratification and blooms in deep pelagic systems. First, earlier studies (Riley, 1942, for example) suggest a monotonic increase in surface layer production as the surface layer shallows. Our model results suggest, however, a nonmonotonic relationship between phytoplankton population growth and surface layer depth, which results from a balance between several 'competing' processes, including the interaction of sinking with turbulent mixing and average net growth occurring within the surface layer. Second, we show that the traditional SCDM must be refined for application to energetic shallow systems or for systems in which surface layer mixing is not strong enough to counteract the sinking loss of phytoplankton. This need for refinement arises because of the leakage of phytoplankton from the surface layer by turbulent diffusion and sinking, processes not considered in the classical SCDM. Our model shows that, even for low sinking rates and small turbulent diffusivities, a significant % of the phytoplankton biomass produced in the surface layer can be lost by these processes.

Blended Wing Body (BWB) Boundary Layer Ingestion (BLI) Inlet Configuration and System Studies

NASA Technical Reports Server (NTRS)

Kawai, Ronald T.; Friedman, Douglas M.; Serrano, Leonel

2006-01-01

A study was conducted to determine the potential reduction in fuel burned for BLI (boundary layer ingestion) inlets on a BWB (blended wing body) airplane employing AFC (active flow control). The BWB is a revolutionary type airplane configuration with engines on the aft upper surface where thick boundary layer offers the greatest opportunity for ram drag reduction. AFC is an emerging technology for boundary layer control. Several BLI inlet configurations were analyzed in the NASA-developed RANS Overflow CFD code. The study determined that, while large reductions in ram drag result from BLI, lower inlet pressure recovery produces engine performance penalties that largely offset this ram drag reduction. AFC could, however, enable a short BLI inlet that allows surface mounting of the engine which, when coupled with a short diffuser, would significantly reduce drag and weight for a potential 10% reduction in fuel burned. Continuing studies are therefore recommended to achieve this reduction in fuel burned considering the use of more modest amounts of BLI coupled with both AFC and PFC (Passive Flow Control) to produce a fail-operational system.

Single-Step Electrophoretic Deposition of Non-noble Metal Catalyst Layer with Low Onset Voltage for Ethanol Electro-oxidation.

PubMed

Ahmadi Daryakenari, Ahmad; Hosseini, Davood; Ho, Ya-Lun; Saito, Takumi; Apostoluk, Aleksandra; Müller, Christoph R; Delaunay, Jean-Jacques

2016-06-29

A single-step electrophoretic deposition (EPD) process is used to fabricate catalyst layers which consist of nickel oxide nanoparticles attached on the surface of nanographitic flakes. Magnesium ions present in the colloid charge positively the flake's surface as they attach on it and are also used to bind nanographitic flakes together. The fabricated catalyst layers showed a very low onset voltage (-0.2 V vs Ag/AgCl) in the electro-oxidation of ethanol. To clarify the occurring catalytic mechanism, we performed annealing treatment to produce samples having a different electrochemical behavior with a large onset voltage. Temperature dependence measurements of the layer conductivity pointed toward a charge transport mechanism based on hopping for the nonannealed layers, while the drift transport is observed in the annealed layers. The hopping charge transport is responsible for the appearance of the low onset voltage in ethanol electro-oxidation.

The optimal SAM surface functional group for producing a biomimetic HA coating on Ti.

PubMed

Liu, D P; Majewski, P; O'Neill, B K; Ngothai, Y; Colby, C B

2006-06-15

Commercial interest is growing in biomimetic methods that employ self assembled mono-layers (SAMs) to produce biocompatible HA coatings on Ti-based orthopedic implants. Recently, separate studies have considered HA formation for various SAM surface functional groups. However, these have often neglected to verify crystallinity of the HA coating, which is essential for optimal bioactivity. Furthermore, differing experimental and analytical methods make performance comparisons difficult. This article investigates and evaluates HA formation for four of the most promising surface functional groups: --OH, --SO(3)H, --PO(4)H(2) and --COOH. All of them successfully formed a HA coating at Ca/P ratios between 1.49 and 1.62. However, only the --SO(3)H and --COOH end groups produced a predominantly crystalline HA. Furthermore, the --COOH end group yielded the thickest layer and possessed crystalline characteristics very similar to that of the human bone. The --COOH end group appears to provide the optimal SAM surface interface for nucleation and growth of biomimetic crystalline HA. Intriguingly, this finding may lend support to explanations elsewhere of why human bone sialoprotein is such a potent nucleator of HA and is attributed to the protein's glutamic acid-rich sequences.

Ellipsometric surface analysis of wear tracks produced by different lubricants

NASA Technical Reports Server (NTRS)

Lauer, J. L.; Marxer, N.; Jones, W. R., Jr.

1985-01-01

Ellipsometric analyses of wear tracks in berings of M-50 steel were carried out after operation under severe conditions with different lubricant additives. The base lubricant was a synthetic ester. It was found that the surface and wear additives benzotirazole and tricresylyphosphate produced very patchy oxide layers. Dioctyldiphenylamine, a common antioxidant, on the other hand produced smoother films. The analyses were performed with a specially designed and constructed ellipsometer of very high (20 micron) spatial resolution. The results are consistent with data obtained by Auger electron spectroscopy.

Osteoinduction on Acid and Heat Treated Porous Ti Metal Samples in Canine Muscle

PubMed Central

Kawai, Toshiyuki; Takemoto, Mitsuru; Fujibayashi, Shunsuke; Akiyama, Haruhiko; Tanaka, Masashi; Yamaguchi, Seiji; Pattanayak, Deepak K.; Doi, Kenji; Matsushita, Tomiharu; Nakamura, Takashi; Kokubo, Tadashi; Matsuda, Shuichi

2014-01-01

Samples of porous Ti metal were subjected to different acid and heat treatments. Ectopic bone formation on specimens embedded in dog muscle was compared with the surface characteristics of the specimen. Treatment of the specimens by H2SO4/HCl and heating at 600°C produced micrometer-scale roughness with surface layers composed of rutile phase of titanium dioxide. The acid- and heat-treated specimens induced ectopic bone formation within 6 months of implantation. A specimen treated using NaOH followed by HCl acid and then heat treatment produced nanometer-scale surface roughness with a surface layer composed of both rutile and anatase phases of titanium dioxide. These specimens also induced bone formation after 6 months of implantation. Both these specimens featured positive surface charge and good apatite-forming abilities in a simulated body fluid. The amount of the bone induced in the porous structure increased with apatite-forming ability and higher positive surface charge. Untreated porous Ti metal samples showed no bone formation even after 12 months. Specimens that were only heat treated featured a smooth surface composed of rutile. A mixed acid treatment produced specimens with micrometer-scale rough surfaces composed of titanium hydride. Both of them also showed no bone formation after 12 months. The specimens that showed no bone formation also featured almost zero surface charge and no apatite-forming ability. These results indicate that osteoinduction of these porous Ti metal samples is directly related to positive surface charge that facilitates formation of apatite on the metal surfaces in vitro. PMID:24520375

Technology of Strengthening Steel Details by Surfacing Composite Coatings

NASA Astrophysics Data System (ADS)

Burov, V. G.; Bataev, A. A.; Rakhimyanov, Kh M.; Mul, D. O.

2016-04-01

The article considers the problem of forming wear resistant meal ceramic coatings on steel surfaces using the results of our own investigations and the analysis of achievements made in the country and abroad. Increasing the wear resistance of surface layers of steel details is achieved by surfacing composite coatings with carbides or borides of metals as disperse particles in the strengthening phase. The use of surfacing on wearing machine details and mechanisms has a history of more than 100 years. But still engineering investigations in this field are being conducted up to now. The use of heating sources which provide a high density of power allows ensuring temperature and time conditions of surfacing under which composites with peculiar service and functional properties are formed. High concentration of energy in the zone of melt, which is created from powder mixtures and the hardened surface layer, allows producing the transition zone between the main material and surfaced coating. Surfacing by the electron beam directed from vacuum to the atmosphere is of considerable technological advantages. They give the possibility of strengthening surface layers of large-sized details by surfacing powder mixtures without their preliminary compacting. A modified layer of the main metal with ceramic particles distributed in it is created as a result of heating surfaced powders and the detail surface layer by the electron beam. Technology of surfacing allows using powders of refractory metals and graphite in the composition of powder mixtures. They interact with one another and form the particles of the hardening phase of the composition coating. The chemical composition of the main and surfaced materials is considered to be the main factor which determines the character of metallurgical processes in local zones of melt as well as the structure and properties of surfaced composition.

Method for producing ceramic composition having low friction coefficient at high operating temperatures

DOEpatents

Lankford, Jr., James

1988-01-01

A method for producing a stable ceramic composition having a surface with a low friction coefficient and high wear resistance at high operating temperatures. A first deposition of a thin film of a metal ion is made upon the surface of the ceramic composition and then a first ion implantation of at least a portion of the metal ion is made into the near surface region of the composition. The implantation mixes the metal ion and the ceramic composition to form a near surface composite. The near surface composite is then oxidized sufficiently at high oxidizing temperatures to form an oxide gradient layer in the surface of the ceramic composition.

Surface-enhanced Raman scattering of amorphous TiO2 thin films by gold nanostructures: Revealing first layer effect with thickness variation

NASA Astrophysics Data System (ADS)

Degioanni, S.; Jurdyc, A.-M.; Bessueille, F.; Coulm, J.; Champagnon, B.; Vouagner, D.

2013-12-01

In this paper, amorphous titanium dioxide (TiO2) thin films have been deposited on a commercially available Klarite substrate using the sol-gel process to produce surface-enhanced Raman scattering (SERS). The substrate consists of square arrays of micrometer-sized pyramidal pits in silicon with a gold coating. Several thin TiO2 layers have been deposited on the surface to study the influence of film thickness. Ultimately, we obtained information on SERS of an amorphous TiO2 layer by gold nanostructures, whose range is less than a few nanometers. Mechanisms responsible for the enhancement are the product of concomitant chemical and electromagnetic effects with an important contribution from plasmon-induced charge transfer.

Nanopatterned articles produced using reconstructed block copolymer films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russell, Thomas P.; Park, Soojin; Wang;, Jia-Yu

Nanopatterned surfaces are prepared by a method that includes forming a block copolymer film on a substrate, annealing and surface reconstructing the block copolymer film to create an array of cylindrical voids, depositing a metal on the surface-reconstructed block copolymer film, and heating the metal-coated block copolymer film to redistribute at least some of the metal into the cylindrical voids. When very thin metal layers and low heating temperatures are used, metal nanodots can be formed. When thicker metal layers and higher heating temperatures are used, the resulting metal structure includes nanoring-shaped voids. The nanopatterned surfaces can be transferred tomore » the underlying substrates via etching, or used to prepare nanodot- or nanoring-decorated substrate surfaces.« less

Surfactant-associated bacteria in the near-surface layer of the ocean.

PubMed

Kurata, Naoko; Vella, Kate; Hamilton, Bryan; Shivji, Mahmood; Soloviev, Alexander; Matt, Silvia; Tartar, Aurélien; Perrie, William

2016-01-12

Certain marine bacteria found in the near-surface layer of the ocean are expected to play important roles in the production and decay of surface active materials; however, the details of these processes are still unclear. Here we provide evidence supporting connection between the presence of surfactant-associated bacteria in the near-surface layer of the ocean, slicks on the sea surface, and a distinctive feature in the synthetic aperture radar (SAR) imagery of the sea surface. From DNA analyses of the in situ samples using pyrosequencing technology, we found the highest abundance of surfactant-associated bacterial taxa in the near-surface layer below the slick. Our study suggests that production of surfactants by marine bacteria takes place in the organic-rich areas of the water column. Produced surfactants can then be transported to the sea surface and form slicks when certain physical conditions are met. This finding has potential applications in monitoring organic materials in the water column using remote sensing techniques. Identifying a connection between marine bacteria and production of natural surfactants may provide a better understanding of the global picture of biophysical processes at the boundary between the ocean and atmosphere, air-sea exchange of greenhouse gases, and production of climate-active marine aerosols.

Surfactant-associated bacteria in the near-surface layer of the ocean

PubMed Central

Kurata, Naoko; Vella, Kate; Hamilton, Bryan; Shivji, Mahmood; Soloviev, Alexander; Matt, Silvia; Tartar, Aurélien; Perrie, William

2016-01-01

Certain marine bacteria found in the near-surface layer of the ocean are expected to play important roles in the production and decay of surface active materials; however, the details of these processes are still unclear. Here we provide evidence supporting connection between the presence of surfactant-associated bacteria in the near-surface layer of the ocean, slicks on the sea surface, and a distinctive feature in the synthetic aperture radar (SAR) imagery of the sea surface. From DNA analyses of the in situ samples using pyrosequencing technology, we found the highest abundance of surfactant-associated bacterial taxa in the near-surface layer below the slick. Our study suggests that production of surfactants by marine bacteria takes place in the organic-rich areas of the water column. Produced surfactants can then be transported to the sea surface and form slicks when certain physical conditions are met. This finding has potential applications in monitoring organic materials in the water column using remote sensing techniques. Identifying a connection between marine bacteria and production of natural surfactants may provide a better understanding of the global picture of biophysical processes at the boundary between the ocean and atmosphere, air-sea exchange of greenhouse gases, and production of climate-active marine aerosols. PMID:26753514

Geologic Surface Effects of Underground Nuclear Testing, Buckboard Mesa, Climax Stock, Dome Mountain, Frenchman Flat, Rainier/Aqueduct Mesa, and Shoshone Mountain, Nevada Test Site, Nevada

USGS Publications Warehouse

Grasso, Dennis N.

2003-01-01

Surface effects maps were produced for 72 of 89 underground detonations conducted at the Frenchman Flat, Rainier Mesa and Aqueduct Mesa, Climax Stock, Shoshone Mountain, Buckboard Mesa, and Dome Mountain testing areas of the Nevada Test Site between August 10, 1957 (Saturn detonation, Area 12) and September 18, 1992 (Hunters Trophy detonation, Area 12). The ?Other Areas? Surface Effects Map Database, which was used to construct the maps shown in this report, contains digital reproductions of these original maps. The database is provided in both ArcGIS (v. 8.2) geodatabase format and ArcView (v. 3.2) shapefile format. This database contains sinks, cracks, faults, and other surface effects having a combined (cumulative) length of 136.38 km (84.74 mi). In GIS digital format, the user can view all surface effects maps simultaneously, select and view the surface effects of one or more sites of interest, or view specific surface effects by area or site. Three map layers comprise the database. They are: (1) the surface effects maps layer (oase_n27f), (2) the bar symbols layer (oase_bar_n27f), and (3) the ball symbols layer (oase_ball_n27f). Additionally, an annotation layer, named 'Ball_and_Bar_Labels,' and a polygon features layer, named 'Area12_features_poly_n27f,' are contained in the geodatabase version of the database. The annotation layer automatically labels all 295 ball-and-bar symbols shown on these maps. The polygon features layer displays areas of ground disturbances, such as rock spall and disturbed ground caused by the detonations. Shapefile versions of the polygon features layer in Nevada State Plane and Universal Transverse Mercator projections, named 'area12_features_poly_n27f.shp' and 'area12_features_poly_u83m.shp,' are also provided in the archive.

Calculation and simulation of atmospheric refraction effects in maritime environments

NASA Astrophysics Data System (ADS)

Dion, Denis, Jr.; Gardenal, Lionel; Lahaie, P.; Forand, J. Luc

2001-01-01

Near the sea surface, atmospheric refraction and turbulence affect both IR transmission and image quality. This produces an impact on both the detection and classification/identification of targets. With the financial participation of the U.S. Office of Naval Research (ONR), Canada's Defence Research Establishment Valcartier (DREV) is developing PRIME (Propagation Resources In the Maritime Environment), a computer model aimed at describing the overall atmospheric effects on IR imagery systems in the marine surface layer. PRIME can be used as a complement to MODTRAN to compute the effective transmittance in the marine surface layer, taking into account the lens effects caused by refraction. It also provides information on image degradation caused by both refraction and turbulence. This paper reviews the refraction phenomena that take place in the surface layer and discusses their effects on target detection and identification. We then show how PRIME can benefit detection studies and image degradation simulations.

The relationship between surface topography, gravity anomalies, and temperature structure of convection

NASA Technical Reports Server (NTRS)

Parsons, B.; Daly, S.

1983-01-01

Consideration is given to the relationship between the temperature structure of mantle convection and the resulting surface topography and gravity anomalies, which are used in its investigation. Integral expressions relating the three variables as a function of wavelength are obtained with the use of Green's function solutions to the equations of motion for the case of constant-viscosity convection in a plane layer subject to a uniform gravitational field. The influence of the boundary conditions, particularly at large wavelengths, is pointed out, and surface topographies and gravity produced by convection are illustrated for a number of simple temperature distributions. It is shown that the upper thermal boundary layer plays an important role in determining the surface observables, while temperatures near the bottom of the layer affect mainly that boundary. This result is consistent with an explanation of geoid anomalies over mid-ocean swells in terms of convection beneath the lithosphere.

Synthesis and immobilization of Ag(0) nanoparticles on diazonium modified electrodes: SECM and cyclic voltammetry studies of the modified interfaces.

PubMed

Noël, Jean-Marc; Zigah, Dodzi; Simonet, Jacques; Hapiot, Philippe

2010-05-18

A versatile method was used to prepare modified surfaces on which metallic silver nanoparticles are immobilized on an organic layer. The preparation method takes advantage, on one hand, of the activated reactivity of some alkyl halides with Ag-Pd alloys to produce metallic silver nanoparticles and, on the other hand, of the facile production of an anchoring polyphenyl acetate layer by the electrografting of substituted diazonium salts on carbon surfaces. Transport properties inside such modified layers were investigated by cyclic voltammetry, scanning electrochemical microscopy (SECM) in feedback mode, and conducting AFM imaging for characterizing the presence and nature of the conducting pathways. The modification of the blocking properties of the surface (or its conductivity) was found to vary to a large extent on the solvents used for surface examination (H(2)O, CH(2)Cl(2), and DMF).

Devices based on surface plasmon interference filters

NASA Technical Reports Server (NTRS)

Wang, Yu (Inventor)

2001-01-01

Devices based on surface plasmon filters having at least one metal-dielectric interface to support surface plasmon waves. A multi-layer-coupled surface plasmon notch filter is provided to have more than two symmetric metal-dielectric interfaces coupled with one another to produce a transmission spectral window with desired spectral profile and bandwidth. Such notch filters can form various color filtering devices for color flat panel displays.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ajayi, O. O.; Lorenzo-Martin, Cinta

This study presents results of an experimental study to evaluate friction stir processing (FSP) with and without hard second-phase particle incorporation as a means to enhance surface properties and wear performance of C86300 manganese bronze alloy. FSP of flat bronze alloy specimens was conducted with hardened H-13 tool steel to create a 3-mm-thick processed surface layer. The process was also used to incorporate B 4C particles, thereby creating a metal-matrix composite layer on the alloy surface. FSP alone was observed to produce substantial reduction in grain size (from an initial value of 350 mu m to 1-5 μm). FSP withoutmore » particle incorporation resulted in modest surface hardening due to grain refinement and dispersion hardening. Under lubricated contact in block-on-ring testing with a hardened steel counter face, FSP produced substantial reduction (about 3X) in bronze wear after polishing of processing surface roughening. FSP with hard B 4C second-phase particle incorporation further reduced wear by up to 20X. The improvement in wear behavior is attributed to grain refinement and load shielding by second-phase particles, as determined by wear mechanism analysis.« less

Influence of Epicuticular Physicochemical Properties on Porcine Rotavirus Adsorption to 24 Leafy Green Vegetables and Tomatoes

PubMed Central

Palma-Salgado, Sindy Paola; Storm, Andrew Page; Feng, Hao; Juvik, John A.; Nguyen, Thanh H.

2015-01-01

Foodborne diseases are a persistent problem in the United States and worldwide. Fresh produce, especially those used as raw foods like salad vegetables, can be contaminated, causing illness. In this study, we determined the number of rotaviruses adsorbed on produce surfaces using group A porcine rotaviruses and 24 cultivars of leafy vegetables and tomato fruits. We also characterized the physicochemical properties of each produce’s outermost surface layer, known as the epicuticle. The number of rotaviruses found on produce surfaces varied among cultivars. Three-dimensional crystalline wax structures on the epicuticular surfaces were found to significantly contribute to the inhibition of viral adsorption to the produce surfaces (p = 0.01). We found significant negative correlations between the number of rotaviruses adsorbed on the epicuticular surfaces and the concentrations of alkanes, fatty acids, and total waxes on the epicuticular surfaces. Partial least square model fitting results suggest that alkanes, ketones, fatty acids, alcohols, contact angle and surface roughness together can explain 60% of the variation in viral adsorption. The results suggest that various fresh produce surface properties need to be collectively considered for efficient sanitation treatments. Up to 10.8% of the originally applied rotaviruses were found on the produce surfaces after three washing treatments, suggesting a potential public health concern regarding rotavirus contamination. PMID:26181904

Composite oxygen transport membrane

DOEpatents

Christie, Gervase Maxwell; Lane, Jonathan A.

2014-08-05

A method of producing a composite oxygen ion membrane and a composite oxygen ion membrane in which a porous fuel oxidation layer and a dense separation layer and optionally, a porous surface exchange layer are formed on a porous support from mixtures of (Ln.sub.1-xA.sub.x).sub.wCr.sub.1-yB.sub.yO.sub.3-.delta. and a doped zirconia. In the porous fuel oxidation layer and the optional porous surface exchange layer, A is Calcium and in the dense separation layer A is not Calcium and, preferably is Strontium. Preferred materials are (La.sub.0.8Ca.sub.0.2).sub.0.95Cr.sub.0.5Mn.sub.0.5O.sub.3-.delta. for the porous fuel oxidation and optional porous surface exchange layers and (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.5Fe.sub.0.5O.sub.3-.delta. for the dense separation layer. The use of such materials allows the membrane to sintered in air and without the use of pore formers to reduce membrane manufacturing costs. The use of materials, as described herein, for forming the porous layers have application for forming any type of porous structure, such as a catalyst support.

Composite oxygen transport membrane

DOEpatents

Christie, Gervase Maxwell; Lane, Jonathan A.

2016-11-15

A method of producing a composite oxygen ion membrane and a composite oxygen ion membrane in which a porous fuel oxidation layer and a dense separation layer and optionally, a porous surface exchange layer are formed on a porous support from mixtures of (Ln.sub.1-xA.sub.x).sub.wCr.sub.1-yB.sub.yO.sub.3-.delta. and a doped zirconia. In the porous fuel oxidation layer and the optional porous surface exchange layer, A is Calcium and in the dense separation layer A is not Calcium and, preferably is Strontium. Preferred materials are (La.sub.0.8Ca.sub.0.2).sub.0.95Cr.sub.0.5Mn.sub.0.5O.sub.3-.delta. for the porous fuel oxidation and optional porous surface exchange layers and (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.5Fe.sub.0.5O.sub.3-.delta. for the dense separation layer. The use of such materials allows the membrane to sintered in air and without the use of pore formers to reduce membrane manufacturing costs. The use of materials, as described herein, for forming the porous layers have application for forming any type of porous structure, such as a catalyst support.

Regenerator seal

DOEpatents

Davis, Leonard C.; Pacala, Theodore; Sippel, George R.

1981-01-01

A method for manufacturing a hot side regenerator cross arm seal assembly having a thermally stablilized wear coating with a substantially flat wear surface thereon to seal between low pressure and high pressure passages to and from the hot inboard side of a rotary regenerator matrix includes the steps of forming a flat cross arm substrate member of high nickel alloy steel; fixedly securing the side edges of the substrate member to a holding fixture with a concave surface thereacross to maintain the substrate member to a slightly bent configuration on the fixture surface between the opposite ends of the substrate member to produce prestress therein; applying coating layers on the substrate member including a wear coating of plasma sprayed nickel oxide/calcium flouride material to define a wear surface of slightly concave form across the restrained substrate member between the free ends thereon; and thereafter subjecting the substrate member and the coating thereon to a heat treatment of 1600.degree. F. for sixteen hours to produce heat stabilizing growth in the coating layers on the substrate member and to produce a thermally induced growth stress in the wear surface that substantially equalizes the prestress in the substrate whereby when the cross arm is removed from the fixture surface following the heat treatment step a wear face is formed on the cross arm assembly that will be substantially flat between the ends.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Eun-Kyeong; Yeong Kim, Ji; Sub Kim, Sang, E-mail: sangsub@inha.ac.kr

We describe the preparation of superhydrophobic SiO{sub 2} layers through a combination of surface roughness and fluorination. Electrospraying SiO{sub 2} precursor solutions that were prepared by a sol-gel route and included trichloro(1H,1H,2H,2H-perfluorooctyl)silane as a fluorination source produced highly rough, fluorinated SiO{sub 2} layers. In sharp contrast to the fluorinated flat SiO{sub 2} layer, the fluorinated rough SiO{sub 2} layer showed much enhanced repellency toward liquid droplets of different surface tensions. The surface fraction and the work of adhesion of the superhydrophobic SiO{sub 2} layers were determined, respectively, based on Cassie-Baxter and Young-Dupre equations. The satisfactory long-term stability for 30 days,more » the ultraviolet resistance and the thermal stability up to 400 {sup o}C of the superhydrophobic SiO{sub 2} layers prepared in this work confirm a promising practical application. - Graphical abstract: A schematic illustration of the electrospray deposition used for preparing SiO{sub 2} layers. Shapes of liquid droplets of water, glycerol, coffee, juice and milk created on the fluorinated rough SiO{sub 2} layer deposited on a silicon wafer. Highlights: Black-Right-Pointing-Pointer Superhydrophobic SiO{sub 2} layers are realized by a combination of surface roughness and fluorination. Black-Right-Pointing-Pointer The fluorinated rough SiO{sub 2} layer shows enhanced repellency toward various liquid droplets. Black-Right-Pointing-Pointer The wetting behavior is explained based on Cassie-Baxter and Young-Dupre equations. Black-Right-Pointing-Pointer The superhydrophobic SiO{sub 2} layers confirm a promising practical application.« less

Surface engineering of nanoparticles in suspension for particle based bio-sensing

PubMed Central

Sen, Tapas; Bruce, Ian J.

2012-01-01

Surface activation of nanoparticles in suspension using amino organosilane has been carried out via strict control of a particle surface ad-layer of water using a simple but efficient protocol ‘Tri-phasic Reverse Emulsion’ (TPRE). This approach produced thin and ordered layers of particle surface functional groups which allowed the efficient conjugation of biomolecules. When used in bio-sensing applications, the resultant conjugates were highly efficient in the hybrid capture of complementary oligonucleotides and the detection of food borne microorganism. TPRE overcomes a number of fundamental problems associated with the surface modification of particles in aqueous suspension viz. particle aggregation, density and organization of resultant surface functional groups by controlling surface condensation of the aminosilane. The approach has potential for application in areas as diverse as nanomedicine, to food technology and industrial catalysis. PMID:22872809

Femtosecond laser fabrication of sub-diffraction nanoripples on wet Al surface in multi-filamentation regime: High optical harmonics effects?

NASA Astrophysics Data System (ADS)

Ionin, A. A.; Kudryashov, S. I.; Makarov, S. V.; Rudenko, A. A.; Saltuganov, P. N.; Seleznev, L. V.; Sinitsyn, D. V.; Sunchugasheva, E. S.

2014-02-01

Relief ripples with sub-diffraction periods (≈λlas/3, λlas/4) were produced on a aluminum surface immersed in water and irradiated in a multi-filamentation regime by focused 744 nm femtosecond laser pulses with highly supercritical, multi-GW peak powers. For the VUV (8.5 eV) surface plasmon resonance on the wet aluminum surface, such small-scale surface nanogratings can be produced by high - second and third - optical harmonics, coming to the surface from the optical filaments in the water layer. Then, the sub-diffraction surface ripples may appear through interference of their transverse electric fields with the longitudinal electric fields of their counterparts, scattered on the surface roughness and appeared as the corresponding high-energy, high-wavenumber surface polaritons.

Superhydrophobicity of electrospray-synthesized fluorinated silica layers.

PubMed

Kim, Eun-Kyeong; Lee, Chul-Sung; Kim, Sang Sub

2012-02-15

The preparation of superhydrophobic SiO(2) layers through a combination of a nanoscale surface roughness and a fluorination treatment is reported. Electrospraying SiO(2) precursor solutions that had been prepared by a sol-gel chemical route produced very rough SiO(2) layers. Subsequent fluorination treatment with a solution containing trichloro(1H,1H,2H,2H-perfluorooctyl)silane resulted in highly rough, fluorinated SiO(2) layers. The fluorinated rough SiO(2) layers exhibited excellent repellency toward various liquid droplets. In particular, water repellency of 168° was observed. On the bases of Cassie-Baxter and Young-Dupre equations, the surface fraction and the work of adhesion of the rough, fluorinated SiO(2) layers were respectively estimated. In light of the durability in water, ultraviolet resistance, and thermal stability, the superhydrophobic SiO(2) layers prepared in this work hold promise in a range of practical applications. Copyright © 2011 Elsevier Inc. All rights reserved.

Application of Polypyrrole Multi-Walled Carbon Nanotube Composite Layer for Detection of Mercury, Lead and Iron Ions Using Surface Plasmon Resonance Technique

PubMed Central

Sadrolhosseini, Amir Reza; Noor, A. S. M.; Bahrami, Afarin; Lim, H. N.; Talib, Zainal Abidin; Mahdi, Mohd. Adzir

2014-01-01

Polypyrrole multi-walled carbon nanotube composite layers were used to modify the gold layer to measure heavy metal ions using the surface plasmon resonance technique. The new sensor was fabricated to detect trace amounts of mercury (Hg), lead (Pb), and iron (Fe) ions. In the present research, the sensitivity of a polypyrrole multi-walled carbon nanotube composite layer and a polypyrrole layer were compared. The application of polypyrrole multi-walled carbon nanotubes enhanced the sensitivity and accuracy of the sensor for detecting ions in an aqueous solution due to the binding of mercury, lead, and iron ions to the sensing layer. The Hg ion bonded to the sensing layer more strongly than did the Pb and Fe ions. The limitation of the sensor was calculated to be about 0.1 ppm, which produced an angle shift in the region of 0.3° to 0.6°. PMID:24733263

Comparison of some effects of modification of a polylactide surface layer by chemical, plasma, and laser methods

NASA Astrophysics Data System (ADS)

Moraczewski, Krzysztof; Rytlewski, Piotr; Malinowski, Rafał; Żenkiewicz, Marian

2015-08-01

The article presents the results of studies and comparison of selected properties of the modified PLA surface layer. The modification was carried out with three methods. In the chemical method, a 0.25 M solution of sodium hydroxide in water and ethanol was utilized. In the plasma method, a 50 W generator was used, which produced plasma in the air atmosphere under reduced pressure. In the laser method, a pulsed ArF excimer laser with fluency of 60 mJ/cm2 was applied. Polylactide samples were examined by using the following techniques: scanning electron microscopy (SEM), atomic force microscopy (AFM), goniometry and X-ray photoelectron spectroscopy (XPS). Images of surfaces of the modified samples were recorded, contact angles were measured, and surface free energy was calculated. Qualitative and quantitative analyses of chemical composition of the PLA surface layer were performed as well. Based on the survey it was found that the best modification results are obtained using the plasma method.

Prospect of life on cold planets with low atmospheric pressures

NASA Astrophysics Data System (ADS)

Pavlov, A. A.; Vdovina, M.

2009-12-01

Stable liquid water on the surface of a planet has been viewed as the major requirement for a habitable planet. Such approach would exclude planets with low atmospheric pressures and cold mean surface temperatures (like present Mars) as potential candidates for extraterrestrial life search. Here we explore a possibility of the liquid water formation in the extremely shallow (1-3 cm) subsurface layer under low atmospheric pressures (0.1-10 mbar) and low average surface temperatures (~-30 C). During brief periods of simulated daylight warming the shallow subsurface ice sublimates, the water vapor can diffuse through the porous surface layer of soil temporarily producing supersaturated conditions in the soil, which lead to the formation of liquid films. We show that non-extremophile terrestrial microorganisms (Vibrio sp.) can grow and reproduce under such conditions. The necessary conditions for metabolism and reproduction are the sublimation of ground ice through a thin layer of soil and short episodes of warm temperatures at the planetary surface.

Open carbon nanopipettes as resistive-pulse sensors, rectification sensors, and electrochemical nanoprobes.

PubMed

Hu, Keke; Wang, Yixian; Cai, Huijing; Mirkin, Michael V; Gao, Yang; Friedman, Gary; Gogotsi, Yury

2014-09-16

Nanometer-sized glass and quartz pipettes have been widely used as a core of chemical sensors, patch clamps, and scanning probe microscope tips. Many of those applications require the control of the surface charge and chemical state of the inner pipette wall. Both objectives can be attained by coating the inner wall of a quartz pipette with a nanometer-thick layer of carbon. In this letter, we demonstrate the possibility of using open carbon nanopipettes (CNP) produced by chemical vapor deposition as resistive-pulse sensors, rectification sensors, and electrochemical nanoprobes. By applying a potential to the carbon layer, one can change the surface charge and electrical double-layer at the pipette wall, which, in turn, affect the ion current rectification and adsorption/desorption processes essential for resistive-pulse sensors. CNPs can also be used as versatile electrochemical probes such as asymmetric bipolar nanoelectrodes and dual electrodes based on simultaneous recording of the ion current through the pipette and the current produced by oxidation/reduction of molecules at the carbon nanoring.

Method for producing silicon thin-film transistors with enhanced forward current drive

DOEpatents

Weiner, K.H.

1998-06-30

A method is disclosed for fabricating amorphous silicon thin film transistors (TFTs) with a polycrystalline silicon surface channel region for enhanced forward current drive. The method is particularly adapted for producing top-gate silicon TFTs which have the advantages of both amorphous and polycrystalline silicon TFTs, but without problem of leakage current of polycrystalline silicon TFTs. This is accomplished by selectively crystallizing a selected region of the amorphous silicon, using a pulsed excimer laser, to create a thin polycrystalline silicon layer at the silicon/gate-insulator surface. The thus created polysilicon layer has an increased mobility compared to the amorphous silicon during forward device operation so that increased drive currents are achieved. In reverse operation the polysilicon layer is relatively thin compared to the amorphous silicon, so that the transistor exhibits the low leakage currents inherent to amorphous silicon. A device made by this method can be used, for example, as a pixel switch in an active-matrix liquid crystal display to improve display refresh rates. 1 fig.

Method for producing silicon thin-film transistors with enhanced forward current drive

DOEpatents

Weiner, Kurt H.

1998-01-01

A method for fabricating amorphous silicon thin film transistors (TFTs) with a polycrystalline silicon surface channel region for enhanced forward current drive. The method is particularly adapted for producing top-gate silicon TFTs which have the advantages of both amorphous and polycrystalline silicon TFTs, but without problem of leakage current of polycrystalline silicon TFTs. This is accomplished by selectively crystallizing a selected region of the amorphous silicon, using a pulsed excimer laser, to create a thin polycrystalline silicon layer at the silicon/gate-insulator surface. The thus created polysilicon layer has an increased mobility compared to the amorphous silicon during forward device operation so that increased drive currents are achieved. In reverse operation the polysilicon layer is relatively thin compared to the amorphous silicon, so that the transistor exhibits the low leakage currents inherent to amorphous silicon. A device made by this method can be used, for example, as a pixel switch in an active-matrix liquid crystal display to improve display refresh rates.

Cloud and boundary layer interactions over the Arctic sea-ice in late summer

NASA Astrophysics Data System (ADS)

Shupe, M. D.; Persson, P. O. G.; Brooks, I. M.; Tjernström, M.; Sedlar, J.; Mauritsen, T.; Sjogren, S.; Leck, C.

2013-05-01

Observations from the Arctic Summer Cloud Ocean Study (ASCOS), in the central Arctic sea-ice pack in late summer 2008, provide a detailed view of cloud-atmosphere-surface interactions and vertical mixing processes over the sea-ice environment. Measurements from a suite of ground-based remote sensors, near surface meteorological and aerosol instruments, and profiles from radiosondes and a helicopter are combined to characterize a week-long period dominated by low-level, mixed-phase, stratocumulus clouds. Detailed case studies and statistical analyses are used to develop a conceptual model for the cloud and atmosphere structure and their interactions in this environment. Clouds were persistent during the period of study, having qualities that suggest they were sustained through a combination of advective influences and in-cloud processes, with little contribution from the surface. Radiative cooling near cloud top produced buoyancy-driven, turbulent eddies that contributed to cloud formation and created a cloud-driven mixed layer. The depth of this mixed layer was related to the amount of turbulence and condensed cloud water. Coupling of this cloud-driven mixed layer to the surface boundary layer was primarily determined by proximity. For 75% of the period of study, the primary stratocumulus cloud-driven mixed layer was decoupled from the surface and typically at a warmer potential temperature. Since the near-surface temperature was constrained by the ocean-ice mixture, warm temperatures aloft suggest that these air masses had not significantly interacted with the sea-ice surface. Instead, back trajectory analyses suggest that these warm airmasses advected into the central Arctic Basin from lower latitudes. Moisture and aerosol particles likely accompanied these airmasses, providing necessary support for cloud formation. On the occasions when cloud-surface coupling did occur, back trajectories indicated that these air masses advected at low levels, while mixing processes kept the mixed layer in equilibrium with the near-surface environment. Rather than contributing buoyancy forcing for the mixed-layer dynamics, the surface instead simply appeared to respond to the mixed-layer processes aloft. Clouds in these cases often contained slightly higher condensed water amounts, potentially due to additional moisture sources from below.

Cloud and boundary layer interactions over the Arctic sea ice in late summer

NASA Astrophysics Data System (ADS)

Shupe, M. D.; Persson, P. O. G.; Brooks, I. M.; Tjernström, M.; Sedlar, J.; Mauritsen, T.; Sjogren, S.; Leck, C.

2013-09-01

Observations from the Arctic Summer Cloud Ocean Study (ASCOS), in the central Arctic sea-ice pack in late summer 2008, provide a detailed view of cloud-atmosphere-surface interactions and vertical mixing processes over the sea-ice environment. Measurements from a suite of ground-based remote sensors, near-surface meteorological and aerosol instruments, and profiles from radiosondes and a helicopter are combined to characterize a week-long period dominated by low-level, mixed-phase, stratocumulus clouds. Detailed case studies and statistical analyses are used to develop a conceptual model for the cloud and atmosphere structure and their interactions in this environment. Clouds were persistent during the period of study, having qualities that suggest they were sustained through a combination of advective influences and in-cloud processes, with little contribution from the surface. Radiative cooling near cloud top produced buoyancy-driven, turbulent eddies that contributed to cloud formation and created a cloud-driven mixed layer. The depth of this mixed layer was related to the amount of turbulence and condensed cloud water. Coupling of this cloud-driven mixed layer to the surface boundary layer was primarily determined by proximity. For 75% of the period of study, the primary stratocumulus cloud-driven mixed layer was decoupled from the surface and typically at a warmer potential temperature. Since the near-surface temperature was constrained by the ocean-ice mixture, warm temperatures aloft suggest that these air masses had not significantly interacted with the sea-ice surface. Instead, back-trajectory analyses suggest that these warm air masses advected into the central Arctic Basin from lower latitudes. Moisture and aerosol particles likely accompanied these air masses, providing necessary support for cloud formation. On the occasions when cloud-surface coupling did occur, back trajectories indicated that these air masses advected at low levels, while mixing processes kept the mixed layer in equilibrium with the near-surface environment. Rather than contributing buoyancy forcing for the mixed-layer dynamics, the surface instead simply appeared to respond to the mixed-layer processes aloft. Clouds in these cases often contained slightly higher condensed water amounts, potentially due to additional moisture sources from below.

Chembio extraction on a chip by nanoliter droplet ejection.

PubMed

Yu, Hongyu; Kwon, Jae Wan; Kim, Eun Sok

2005-03-01

This paper describes a novel liquid separation technique for chembio extraction by an ultrasonic nanoliter-liquid-droplet ejector built on a PZT sheet. This technique extracts material from an aqueous two-phase system (ATPS) in a precise amount through digital control of the number of nanoliter droplets, without any mixing between the two liquids in the ATPS. The ultrasonic droplet ejector uses an acoustic streaming effect produced by an acoustic beam focused on the liquid surface, and ejects liquid droplets only from the liquid surface without disturbing most of the liquid below the surface. This unique characteristic of the focused acoustic beam is perfect (1) for separating a top-layer liquid (from the bulk of liquid) that contains particles of interest or (2) for recovering a top-layer liquid that has different phase from a bottom-layer liquid. Three kinds of liquid extraction are demonstrated with the ultrasonic droplet ejector: (1) 16 microl of top layer in Dextran-polyethylene glycol-water ATPS (aqueous two-phase system) is recovered within 20 s; (2) micron sized particles that float on water surface are ejected out with water droplets; and (3) oil layer on top of water is separated out.

Switchable Super-Hydrophilic/Hydrophobic Indium Tin Oxide (ITO) Film Surfaces on Reactive Ion Etching (RIE) Textured Si Wafer.

PubMed

Kim, Hwa-Min; Litao, Yao; Kim, Bonghwan

2015-11-01

We have developed a surface texturing process for pyramidal surface features along with an indium tin oxide (ITO) coating process to fabricate super-hydrophilic conductive surfaces. The contact angle of a water droplet was less than 5 degrees, which means that an extremely high wettability is achievable on super-hydrophilic surfaces. We have also fabricated a super-hydrophobic conductive surface using an additional coating of polytetrafluoroethylene (PTFE) on the ITO layer coated on the textured Si surface; the ITO and PTFE films were deposited by using a conventional sputtering method. We found that a super-hydrophilic conductive surface is produced by ITO coated on the pyramidal Si surface (ITO/Si), with contact angles of approximately 0 degrees and a resistivity of 3 x 10(-4) Ω x cm. These values are highly dependent on the substrate temperature during the sputtering process. We also found that the super-hydrophobic conductive surface produced by the additional coating of PTFE on the pyramidal Si surface with an ITO layer (PTFE/ITO/Si) has a contact angle of almost 160 degrees and a resistivity of 3 x 10(-4) Ω x cm, with a reflectance lower than 9%. Therefore, these processes can be used to fabricate multifunctional features of ITO films for switchable super-hydrophilic and super-hydrophobic surfaces.

Multi-layer carbon-based coatings for field emission

DOEpatents

Sullivan, John P.; Friedmann, Thomas A.

1998-01-01

A multi-layer resistive carbon film field emitter device for cold cathode field emission applications. The multi-layered film of the present invention consists of at least two layers of a conductive carbon material, preferably amorphous-tetrahedrally coordinated carbon, where the resistivities of adjacent layers differ. For electron emission from the surface, the preferred structure can be a top layer having a lower resistivity than the bottom layer. For edge emitting structures, the preferred structure of the film can be a plurality of carbon layers, where adjacent layers have different resistivities. Through selection of deposition conditions, including the energy of the depositing carbon species, the presence or absence of certain elements such as H, N, inert gases or boron, carbon layers having desired resistivities can be produced.

Silicon metal-semiconductor-metal photodetector

DOEpatents

Brueck, Steven R. J.; Myers, David R.; Sharma, Ashwani K.

1997-01-01

Silicon MSM photodiodes sensitive to radiation in the visible to near infrared spectral range are produced by altering the absorption characteristics of crystalline Si by ion implantation. The implantation produces a defected region below the surface of the silicon with the highest concentration of defects at its base which acts to reduce the contribution of charge carriers formed below the defected layer. The charge carriers generated by the radiation in the upper regions of the defected layer are very quickly collected between biased Schottky barrier electrodes which form a metal-semiconductor-metal structure for the photodiode.

Silicon metal-semiconductor-metal photodetector

DOEpatents

Brueck, Steven R. J.; Myers, David R.; Sharma, Ashwani K.

1995-01-01

Silicon MSM photodiodes sensitive to radiation in the visible to near infrared spectral range are produced by altering the absorption characteristics of crystalline Si by ion implantation. The implantation produces a defected region below the surface of the silicon with the highest concentration of defects at its base which acts to reduce the contribution of charge carriers formed below the defected layer. The charge carriers generated by the radiation in the upper regions of the defected layer are very quickly collected between biased Schottky barrier electrodes which form a metal-semiconductor-metal structure for the photodiode.

Medicine Delivery Device with Integrated Sterilization and Detection

NASA Technical Reports Server (NTRS)

Sheam, Michael J.; Greer, Harold F.; Manohara, Harish

2013-01-01

Sterile delivery devices can be created by integrating a medicine delivery instrument with surfaces that are coated with germicidal and anti-fouling material. This requires that a large-surface-area template be developed within a constrained volume to ensure good contact between the delivered medicine and the germicidal material. Both of these can be integrated using JPL-developed silicon nanotip or cryo-etch black silicon technologies with atomic layer deposition (ALD) coating of specific germicidal layers. Nanofabrication techniques that are used to produce a microfluidics device are also capable of synthesizing extremely hig-hsurface-area templates in precise locations, and coating those surfaces with conformal films to manipulate their surface properties. This methodology has been successfully applied at JPL to produce patterned and coated silicon nanotips (also known as black silicon) to manipulate the hydrophilicity of surfaces to direct the spreading of fluids in microdevices. JPL s ALD technique is an ideal method to produce the highly conformal coatings required for this type of application. Certain materials, such as TiO2, have germicidal and anti-fouling properties when they are illuminated with UV light. The proposed delivery device contacts medicine with this high-surface-area black silicon surface coated with a thin-film germicidal deposited conformally with ALD. The coating can also be illuminated with ultraviolet light for the purpose of sterilization or identification of the medicine itself. This constrained volume that is located immediately prior to delivery into a patient, ensures that the medicine delivery device is inherently sterile.

Enhancement of bronze alloy surface properties by FSP second-phase particle incorporation

DOE PAGES

Ajayi, O. O.; Lorenzo-Martin, Cinta

2017-06-15

This study presents results of an experimental study to evaluate friction stir processing (FSP) with and without hard second-phase particle incorporation as a means to enhance surface properties and wear performance of C86300 manganese bronze alloy. FSP of flat bronze alloy specimens was conducted with hardened H-13 tool steel to create a 3-mm-thick processed surface layer. The process was also used to incorporate B 4C particles, thereby creating a metal-matrix composite layer on the alloy surface. FSP alone was observed to produce substantial reduction in grain size (from an initial value of 350 mu m to 1-5 μm). FSP withoutmore » particle incorporation resulted in modest surface hardening due to grain refinement and dispersion hardening. Under lubricated contact in block-on-ring testing with a hardened steel counter face, FSP produced substantial reduction (about 3X) in bronze wear after polishing of processing surface roughening. FSP with hard B 4C second-phase particle incorporation further reduced wear by up to 20X. The improvement in wear behavior is attributed to grain refinement and load shielding by second-phase particles, as determined by wear mechanism analysis.« less

Surface heating and patchiness in the coastal ocean off central California during a wind relaxation event

NASA Technical Reports Server (NTRS)

Ramp, Steven R.; Garwood, Roland W.; Snow, Richard L.; Davis, Curtiss O.

1991-01-01

The difference between the temperature of the ocean at 4-cm and 2-m depth was continuously monitored during a cruise to the coastal transition zone off Point Arena, California, during June 1987. The two temperatures were coincident most of the time but diverged during one nearshore leg of the cruise where large temperature differences of up to 4.7 C were observed between the 4-cm and 2-m sensors, in areas which were separated by regions where the two temperatures were coincident as usual. The spatial scale of this 'patchy' thermal structure was about 5-10 km. A mixed layer model (Garwood, 1977) was used to simulate the near surface stratification when forced by the observed wind stress, surface heating, and optical clarity of the water. The model produced a thin strongly stratified surface layer at stations where exceptionally high turbidity was observed but did not produce such features otherwise. This simple model could not explain the horizontal patchiness in the thermal structure, which was likely due to patchiness in the near-surface chlorophyll distributions or to submesoscale variability of the surface wind stress.

Boundary Layer Flow Over a Moving Wavy Surface

NASA Astrophysics Data System (ADS)

Hendin, Gali; Toledo, Yaron

2016-04-01

Boundary Layer Flow Over a Moving Wavy Surface Gali Hendin(1), Yaron Toledo(1) January 13, 2016 (1)School of Mechanical Engineering, Tel-Aviv University, Israel Understanding the boundary layer flow over surface gravity waves is of great importance as various atmosphere-ocean processes are essentially coupled through these waves. Nevertheless, there are still significant gaps in our understanding of this complex flow behaviour. The present work investigates the fundamentals of the boundary layer air flow over progressive, small-amplitude waves. It aims to extend the well-known Blasius solution for a boundary layer over a flat plate to one over a moving wavy surface. The current analysis pro- claims the importance of the small curvature and the time-dependency as second order effects, with a meaningful impact on the similarity pattern in the first order. The air flow over the ocean surface is modelled using an outer, inviscid half-infinite flow, overlaying the viscous boundary layer above the wavy surface. The assumption of a uniform flow in the outer layer, used in former studies, is now replaced with a precise analytical solution of the potential flow over a moving wavy surface with a known celerity, wavelength and amplitude. This results in a conceptual change from former models as it shows that the pressure variations within the boundary layer cannot be neglected. In the boundary layer, time-dependent Navier-Stokes equations are formulated in a curvilinear, orthogonal coordinate system. The formulation is done in an elaborate way that presents additional, formerly neglected first-order effects, resulting from the time-varying coordinate system. The suggested time-dependent curvilinear orthogonal coordinate system introduces a platform that can also support the formulation of turbulent problems for any surface shape. In order to produce a self-similar Blasius-type solution, a small wave-steepness is assumed and a perturbation method is applied. Consequently, a novel self-similar solution is obtained from the first order set of equations. A second order solution is also obtained, stressing the role of small curvature on the boundary layer flow. The proposed model and solution for the boundary layer problem overlaying a moving wavy surface can also be used as a base flow for stability problems that can develop in a boundary layer, including phases of transitional states.

Modelling of Surfaces. Part 2: Metallic Alloy Surfaces Using the BFS Method

NASA Technical Reports Server (NTRS)

Bozzolo, Guillermo; Ferrante, John; Kobistek, Robert J.

1994-01-01

Using BFS, a new semiempirical method for alloys, we study the surface structure of fcc ordered binary alloys. We concentrate on the calculation of surface energies and surface relaxations for the L1(sub 0) and L1(sub 2) ordered structures. Different terminations of the low-index faces are studied. Also, we present results for the interlayer relaxations for planes close to the surface, revealing different relaxations for atoms of different species producing a rippled surface layer.

Development of Cu Clad Cu-Zr Based Metallic Glass and Its Solderability

NASA Astrophysics Data System (ADS)

Terajima, Takeshi; Kimura, Hisamichi; Inoue, Akihisa

Soldering is a candidate technique for joining metallic glasses. It can be processed far below the crystallization temperatures of the various metallic glasses so that there is no possibility of crystallization. However, wettability of Cu-Zr based metallic glass by Pb free solder is poor because a strong surface oxide film interferes direct contact between them. To overcome the problem, Cu thin film clad metallic glass was developed. It was preliminary produced by casting a melt of Cu36Zr48Al8Ag8 pre-alloy into Cu mold cavity, inside which Cu thin film with 2 mm in thickness was set on the wall. Cu36Zr48Al8Ag8 metallic glass, whose surface Cu thin film was welded to, was successfully produced. From the microstructure analyses, it was found that reaction layer was formed at the interface between Cu and Cu36Zr48Al8Ag8 metallic glass, however, there was no oxide in the Cu clad layer. Solderability to the metallic glass was drastically increased. The Cu clad layer played an important role to prevent the formation of surface oxide film and consequently improved the solderability.

Microchannel plate detector and methods for their fabrication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elam, Jeffrey W.; Mane, Anil U.; Peng, Qing

A multi-component tunable resistive coating and methods of depositing the coating on the surfaces of a microchannel plate (MCP) detector. The resistive coating composed of a plurality of alternating layers of a metal oxide resistive component layer and a conductive component layer composed of at least one of a metal, a metal nitride and a metal sulfide. The coating may further include an emissive layer configured to produce a secondary electron emission in response to a particle interacting with the MCP and a neutron-absorbing layer configured to respond to a neutron interacting with the MCP.

Method for fabricating ceramic filaments and high density tape casting method

NASA Technical Reports Server (NTRS)

Collins, Jr., Earl R. (Inventor)

1990-01-01

An apparatus and method is disclosed for fabricating mats of ceramic material comprising preparing a slurry of ceramic particles in a binder/solvent, charging the slurry into a vessel, forcing the slurry from the vessel into spinneret nozzles, discharging the slurry from the nozzles into the path of airjets to enhance the sinuous character of the slurry exudate and to dry it, collecting the filaments on a moving belt so that the filaments overlap each other thereby forming a mat, curing the binder therein, compressing and sintering the mat to form a sintered mat, and crushing the sintered mat to produce filament shaped fragments. A process is also disclosed for producing a tape of densely packed, bonded ceramic particles comprising forming a slurry of ceramic particles and a binder/solvent, applying the slurry to a rotating internal molding surface, applying a large centrifugal force to the slurry to compress it and force excess binder/solvent from the particles, evaporating solvent and curing the binder thereby forming layers of bonded ceramic particles and cured binder, and separating the binder layer from the layer of particles. Multilayers of ceramic particles are cast in an analogous manner on top of previously formed layers. When all of the desired layers have been cast the tape is fired to produce a sintered tape. For example, a three-layer tape is produced having outer layers of highly compressed filament shaped fragments of strontium doped lanthanum (LSM) particles and a center layer of yttria stabilized zicronia (YSZ) particles.

Polyethyleneimine High-Energy Hydrophilic Surface Interfacial Treatment toward Efficient and Stable Perovskite Solar Cells.

PubMed

Li, Pengwei; Liang, Chao; Zhang, Yiqiang; Li, Fengyu; Song, Yanlin; Shao, Guosheng

2016-11-30

The interfacial contact is critical for the performance of perovskite solar cells (PSCs), leading to dense perovskite thin films and efficient charge transport. In this contribution, an effective interfacial treatment solution using polyethyleneimine (PEI) was developed to improve the performance and stability of PSCs. Inserting PEI between the s-VO x and perovskite layers can produce a high-energy hydrophilic surface to facilitate the formation of a high-quality perovskite layer by the solution method. Accordingly, the surface coverage of perovskite film on the s-VO x layer increased from 80% to 95%, and the PCE of the device improved from 12.06% (with an average of 10.16%) to 14.4% (with an average value of 12.8%) under an irradiance of 100 mW cm -2 AM 1.5G sunlight. More importantly, the stability of PSCs was further improved after adding another PEI layer between the electron transport layer and LiF/Al layer, less than 10% decay in efficiency during a 10-days observation. Since all layers of the PSCs were fabricated at low temperature (<150 °C), these PEI-treated PSCs based on the amorphous VO x layer have the potential to contribute significantly toward the development of efficient and stable solar cells on flexible substrates.

Surface transport processes in charged porous media

DOE PAGES

Gabitto, Jorge; Tsouris, Costas

2017-03-03

Surface transport processes are important in chemistry, colloidal sciences, engineering, biology, and geophysics. Natural or externally produced charges on surfaces create electrical double layers (EDLs) at the solid-liquid interface. The existence of the EDLs produces several complex processes including bulk and surface transport of ions. In this work, a model is presented to simulate bulk and transport processes in homogeneous porous media comprising big pores. It is based on a theory for capacitive charging by ideally polarizable porous electrodes without Faradaic reactions or specific adsorption of ions. A volume averaging technique is used to derive the averaged transport equations inmore » the limit of thin electrical double layers. Description of the EDL between the electrolyte solution and the charged wall is accomplished using the Gouy-Chapman-Stern (GCS) model. The surface transport terms enter into the average equations due to the use of boundary conditions for diffuse interfaces. Two extra surface transports terms appear in the closed average equations. One is a surface diffusion term equivalent to the transport process in non-charged porous media. The second surface transport term is a migration term unique to charged porous media. The effective bulk and transport parameters for isotropic porous media are calculated solving the corresponding closure problems.« less

Surface transport processes in charged porous media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gabitto, Jorge; Tsouris, Costas

Surface transport processes are important in chemistry, colloidal sciences, engineering, biology, and geophysics. Natural or externally produced charges on surfaces create electrical double layers (EDLs) at the solid-liquid interface. The existence of the EDLs produces several complex processes including bulk and surface transport of ions. In this work, a model is presented to simulate bulk and transport processes in homogeneous porous media comprising big pores. It is based on a theory for capacitive charging by ideally polarizable porous electrodes without Faradaic reactions or specific adsorption of ions. A volume averaging technique is used to derive the averaged transport equations inmore » the limit of thin electrical double layers. Description of the EDL between the electrolyte solution and the charged wall is accomplished using the Gouy-Chapman-Stern (GCS) model. The surface transport terms enter into the average equations due to the use of boundary conditions for diffuse interfaces. Two extra surface transports terms appear in the closed average equations. One is a surface diffusion term equivalent to the transport process in non-charged porous media. The second surface transport term is a migration term unique to charged porous media. The effective bulk and transport parameters for isotropic porous media are calculated solving the corresponding closure problems.« less

Bonding thermoplastic polymers

DOEpatents

Wallow, Thomas I [Fremont, CA; Hunter, Marion C [Livermore, CA; Krafcik, Karen Lee [Livermore, CA; Morales, Alfredo M [Livermore, CA; Simmons, Blake A [San Francisco, CA; Domeier, Linda A [Danville, CA

2008-06-24

We demonstrate a new method for joining patterned thermoplastic parts into layered structures. The method takes advantage of case-II permeant diffusion to generate dimensionally controlled, activated bonding layers at the surfaces being joined. It is capable of producing bonds characterized by cohesive failure while preserving the fidelity of patterned features in the bonding surfaces. This approach is uniquely suited to production of microfluidic multilayer structures, as it allows the bond-forming interface between plastic parts to be precisely manipulated at micrometer length scales. The bond enhancing procedure is easily integrated in standard process flows and requires no specialized equipment.

The Martian atmospheric planetary boundary layer stability, fluxes, spectra, and similarity

NASA Technical Reports Server (NTRS)

Tillman, James E.

1994-01-01

This is the first analysis of the high frequency data from the Viking lander and spectra of wind, in the Martian atmospheric surface layer, along with the diurnal variation of the height of the mixed surface layer, are calculated for the first time for Mars. Heat and momentum fluxes, stability, and z(sub O) are estimated for early spring, from a surface temperature model and from Viking Lander 2 temperatures and winds at 44 deg N, using Monin-Obukhov similarity theory. The afternoon maximum height of the mixed layer for these seasons and conditions is estimated to lie between 3.6 and 9.2 km. Estimations of this height is of primary importance to all models of the boundary layer and Martian General Circulation Models (GCM's). Model spectra for two measuring heights and three surface roughnesses are calculated using the depth of the mixed layer, and the surface layer parameters and flow distortion by the lander is also taken into account. These experiments indicate that z(sub O), probably lies between 1.0 and 3.0 cm, and most likely is closer to 1.0 cm. The spectra are adjusted to simulate aliasing and high frequency rolloff, the latter caused both by the sensor response and the large Kolmogorov length on Mars. Since the spectral models depend on the surface parameters, including the estimated surface temperature, their agreement with the calculated spectra indicates that the surface layer estimates are self consistent. This agreement is especially noteworthy in that the inertial subrange is virtually absent in the Martian atmosphere at this height, due to the large Kolmogorov length scale. These analyses extend the range of applicability of terrestrial results and demonstrate that it is possible to estimate the effects of severe aliasing of wind measurements, to produce a models which agree well with the measured spectra. The results show that similarity theory developed for Earth applies to Mars, and that the spectral models are universal.

Growth, intermixing, and surface phase formation for zinc tin oxide nanolaminates produced by atomic layer deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hägglund, Carl, E-mail: carl.hagglund@angstrom.uu.se; Grehl, Thomas; Brongersma, Hidde H.

2016-03-15

A broad and expanding range of materials can be produced by atomic layer deposition at relatively low temperatures, including both oxides and metals. For many applications of interest, however, it is desirable to grow more tailored and complex materials such as semiconductors with a certain doping, mixed oxides, and metallic alloys. How well such mixed materials can be accomplished with atomic layer deposition requires knowledge of the conditions under which the resulting films will be mixed, solid solutions, or laminated. The growth and lamination of zinc oxide and tin oxide is studied here by means of the extremely surface sensitivemore » technique of low energy ion scattering, combined with bulk composition and thickness determination, and x-ray diffraction. At the low temperatures used for deposition (150 °C), there is little evidence for atomic scale mixing even with the smallest possible bilayer period, and instead a morphology with small ZnO inclusions in a SnO{sub x} matrix is deduced. Postannealing of such laminates above 400 °C however produces a stable surface phase with a 30% increased density. From the surface stoichiometry, this is likely the inverted spinel of zinc stannate, Zn{sub 2}SnO{sub 4}. Annealing to 800 °C results in films containing crystalline Zn{sub 2}SnO{sub 4}, or multilayered films of crystalline ZnO, Zn{sub 2}SnO{sub 4}, and SnO{sub 2} phases, depending on the bilayer period.« less

Morphologies, microstructures, and mechanical properties of samples produced using laser metal deposition with 316 L stainless steel wire

NASA Astrophysics Data System (ADS)

Xu, Xiang; Mi, Gaoyang; Luo, Yuanqing; Jiang, Ping; Shao, Xinyu; Wang, Chunming

2017-07-01

Laser metal deposition (LMD) with a filler has been demonstrated to be an effective method for additive manufacturing because of its high material deposition efficiency, improved surface quality, reduced material wastage, and cleaner process environment without metal dust pollution. In this study, single beads and samples with ten layers were successfully deposited on a 316 L stainless steel surface under optimized conditions using a 4000 W continuous wave fibre laser and an arc welding machine. The results showed that satisfactory layered samples with a large deposition height and smooth side surface could be achieved under appropriate parameters. The uniform structures had fine cellular and network austenite grains with good metallurgical bonding between layers, showing an austenite solidification mode. Precipitated ferrite at the grain boundaries showed a subgrain structure with fine uniform grain size. A higher microhardness (205-226 HV) was detected in the middle of the deposition area, while the tensile strength of the 50 layer sample reached 669 MPa. In addition, ductile fracturing was proven by the emergence of obvious dimples at the fracture surface.

Durable anti-fogging effect and adhesion improvement on polymer surfaces

NASA Astrophysics Data System (ADS)

Moser, E. M.; Gilliéron, D.; Henrion, G.

2010-01-01

The hydrophobic properties of polymeric surfaces may cause fogging in transparent packaging and poor adhesion to printing colours and coatings. Novel plasma processes for durable functionalization of polypropylene and polyethylene terephthalate substrates were developed and analysed using optical emission spectroscopy. A worm-like nano pattern was created on the polypropylene surface prior to the deposition of thin polar plasma polymerised layers. For both substrates, highly polar surfaces exhibiting a surface tension of up to 69 mN/m and a water contact angle of about 10° were produced - providing the anti-fogging effect. The deposition of thin plasma polymerised layers protects the increased surface areas and enables to tailoring the surface energy of the substrate in a wide range. Wetting characteristics were determined by dynamic contact angle measurements. Investigations of the chemical composition of several layers using X-ray photoelectron spectroscopy and FT-infrared spectroscopy were correlated with functional testing. The surface topography was investigated using atomic force microscopy. The weldability and peeling-off characteristics of the plasma treated polymer films could be adjusted by varying the process parameters. Global and specific migration analyses were undertaken in order to ensure the manufacturing of plasma treated polymer surfaces for direct food contact purposes.

Layered Model for Radiation-Induced Chemical Evolution of Icy Surface Composition on Kuiper Belt and Oort Cloud Bodies

NASA Technical Reports Server (NTRS)

Cooper, John F.; Hill, Matthew E.; Richardson, John D.; Sturner, Steven J.

2010-01-01

The diversity of albedos and surface colors on observed Kuiper Belt and Inner Oort Cloud objects remains to be explained in terms of competition between primordial intrinsic versus exogenic drivers of surface and near-surface evolution. Earlier models have attempted without success to attribute this diversity to the relations between surface radiolysis from cosmic ray irradiation and gardening by meteoritic impacts. A more flexible approach considers the different depth-dependent radiation profiles produced by low-energy plasma, suprathermal, and maximally penetrating charged particles of the heliospheric and local interstellar radiation environments. Generally red objects of the dynamically cold (low inclination, circular orbit) Classical Kuiper Belt might be accounted for from erosive effects of plasma ions and reddening effects of high energy cosmic ray ions, while suprathermal keV-MeV ions could alternatively produce more color neutral surfaces. The deepest layer of more pristine ice can be brought to the surface from meter to kilometer depths by larger impact events and potentially by cryovolcanic activity. The bright surfaces of some larger objects, e.g. Eris, suggest ongoing resurfacing activity. Interactions of surface irradiation, resultant chemical oxidation, and near-surface cryogenic fluid reservoirs have been proposed to account for Enceladus cryovolcanism and may have further applications to other icy irradiated bodies. The diversity of causative processes must be understood to account for observationally apparent diversities of the object surfaces.

Compositional transformations in ion implanted polymers

NASA Astrophysics Data System (ADS)

Abdul-Kader, A. M.; Turos, A.; Grambole, D.; Jagielski, J.; Piątkowska, A.; Madi, N. K.; Al-Maadeed, M.

2005-10-01

Changes of surface layer composition produced by ion bombardment of polyethylene and polypropylene samples were studied. These materials are under consideration for load bearing surfaces in biological and technical applications. To improve their tribological properties, surface layers are usually modified by ionizing radiation. Therefore, to study the mechanism of transformations induced by ion beam bombardment selected polymers were implanted with H, He and Ar ions to the fluences ranging from 1 × 1013 to 2 × 1016/cm2. RBS and NRA techniques were applied for sample analysis. Important hydrogen release was observed with increasing ion dose and was correlated with the ion stopping power. Another important effect observed was the rapid oxidation of samples, which apparently occurs after exposure of implanted samples to the air. Up to 10 at.% of oxygen can be incorporated in the implanted layer.

Inspection Tools

NASA Astrophysics Data System (ADS)

1989-01-01

A "NASA Tech Briefs" article describing an inspection tool and technique known as Optically Stimulated Electron Emission (OSEE) led to the formation of Photo Acoustic Technology, Inc. (PAT). PAT produces sensors and scanning systems which assure surface cleanliness prior to bonding, coating, painting, etc. The company's OP1000 series realtime pre-processing detection capability assures 100 percent surface quality testing. The technique involves brief exposure of the inspection surface to ultraviolet radiation. The energy interacts with the surface layer, causing free electrons to be emitted from the surface to be picked up by the detector. When contamination is present, it interferes with the electron flow in proportion to the thickness of the contaminant layer enabling measurement by system signal output. OP1000 systems operate in conventional atmospheres on all types of material and detect both organic and inorganic contamination.

Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors

PubMed Central

Kawasaki, Shin-ichiro; Suzuki, Akira

2013-01-01

Summary The inner surface of a metallic tube (i.d. 0.5 mm) was coated with a palladium (Pd)-based thin metallic layer by flow electroless plating. Simultaneous plating of Pd and silver (Ag) from their electroless-plating solution produced a mixed distributed bimetallic layer. Preferential acid leaching of Ag from the Pd–Ag layer produced a porous Pd surface. Hydrogenation of p-nitrophenol was examined in the presence of formic acid simply by passing the reaction solution through the catalytic tubular reactors. p-Aminophenol was the sole product of hydrogenation. No side reaction occurred. Reaction conversion with respect to p-nitrophenol was dependent on the catalyst layer type, the temperature, pH, amount of formic acid, and the residence time. A porous and oxidized Pd (PdO) surface gave the best reaction conversion among the catalytic reactors examined. p-Nitrophenol was converted quantitatively to p-aminophenol within 15 s of residence time in the porous PdO reactor at 40 °C. Evolution of carbon dioxide (CO2) was observed during the reaction, although hydrogen (H2) was not found in the gas phase. Dehydrogenation of formic acid did not occur to any practical degree in the absence of p-nitrophenol. Consequently, the nitro group was reduced via hydrogen transfer from formic acid to p-nitrophenol and not by hydrogen generated by dehydrogenation of formic acid. PMID:23843908

Inorganic-organic hybrid coatings on stainless steel by layer-by-layer deposition and surface-initiated atom-transfer-radical polymerization for combating biocorrosion.

PubMed

Yuan, S J; Pehkonen, S O; Ting, Y P; Neoh, K G; Kang, E T

2009-03-01

To improve the biocorrosion resistance of stainless steel (SS) and to confer the bactericidal function on its surface for inhibiting bacterial adhesion and biofilm formation, well-defined inorganic-organic hybrid coatings, consisting of the inner compact titanium oxide multilayers and outer dense poly(vinyl-N-hexylpyridinium) brushes, were successfully developed. Nanostructured titanium oxide multilayer coatings were first built up on the SS substrates via the layer-by-layer sol-gel deposition process. The trichlorosilane coupling agent, containing the alkyl halide atom-transfer-radical polymerization (ATRP) initiator, was subsequently immobilized on the titanium oxide coatings for surface-initiated ATRP of 4-vinylpyridine (4VP). The pyridium nitrogen moieties of the covalently immobilized 4VP polymer, or P(4VP), brushes were quaternized with hexyl bromide to produce a high concentration of quaternary ammonium salt on the SS surfaces. The excellent antibacterial efficiency of the grafted polycations, poly(vinyl-N-pyridinium bromide), was revealed by viable cell counts and atomic force microscopy images of the surface. The effectiveness of the hybrid coatings in corrosion protection was verified by the Tafel plot and electrochemical impedance spectroscopy measurements.

A Method for Measuring the Hardness of the Surface Layer on Hot Forging Dies Using a Nanoindenter

NASA Astrophysics Data System (ADS)

Mencin, P.; van Tyne, C. J.; Levy, B. S.

2009-11-01

The properties and characteristics of the surface layer of forging dies are critical for understanding and controlling wear. However, the surface layer is very thin, and appropriate property measurements are difficult to obtain. The objective of the present study is to determine if nanoindenter testing provides a reliable method, which could be used to measure the surface hardness in forging die steels. To test the reliability of nanoindenter testing, nanoindenter values for two quenched and tempered steels (FX and H13) are compared to microhardness and macrohardness values. These steels were heat treated for various times to produce specimens with different values of hardness. The heat-treated specimens were tested using three different instruments—a Rockwell hardness tester for macrohardness, a Vickers hardness tester for microhardness, and a nanoindenter tester for fine scale evaluation of hardness. The results of this study indicate that nanoindenter values obtained using a Nanoindenter XP Machine with a Berkovich indenter reliably correlate with Rockwell C macrohardness values, and with Vickers HV microhardness values. Consequently, nanoindenter testing can provide reliable results for analyzing the surface layer of hot forging dies.

Large-scale molecular dynamics simulations of TiN/TiN(001) epitaxial film growth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edström, Daniel, E-mail: daned@ifm.liu.se; Sangiovanni, Davide G.; Hultman, Lars

2016-07-15

Large-scale classical molecular dynamics simulations of epitaxial TiN/TiN(001) thin film growth at 1200 K are carried out using incident flux ratios N/Ti = 1, 2, and 4. The films are analyzed as a function of composition, island size distribution, island edge orientation, and vacancy formation. Results show that N/Ti = 1 films are globally understoichiometric with dispersed Ti-rich surface regions which serve as traps to nucleate 111-oriented islands, leading to local epitaxial breakdown. Films grown with N/Ti = 2 are approximately stoichiometric and the growth mode is closer to layer-by-layer, while N/Ti = 4 films are stoichiometric with N-rich surfaces. As N/Ti is increased from 1 to 4, islandmore » edges are increasingly polar, i.e., 110-oriented, and N-terminated to accommodate the excess N flux, some of which is lost by reflection of incident N atoms. N vacancies are produced in the surface layer during film deposition with N/Ti = 1 due to the formation and subsequent desorption of N{sub 2} molecules composed of a N adatom and a N surface atom, as well as itinerant Ti adatoms pulling up N surface atoms. The N vacancy concentration is significantly reduced as N/Ti is increased to 2; with N/Ti = 4, Ti vacancies dominate. Overall, our results show that an insufficient N/Ti ratio leads to surface roughening via nucleation of small dispersed 111 islands, whereas high N/Ti ratios result in surface roughening due to more rapid upper-layer nucleation and mound formation. The growth mode of N/Ti = 2 films, which have smoother surfaces, is closer to layer-by-layer.« less

Surface functionalization of Cu-Ni alloys via grafting of a bactericidal polymer for inhibiting biocorrosion by Desulfovibrio desulfuricans in anaerobic seawater.

PubMed

Yuan, S J; Liu, C K; Pehkonen, S O; Bai, R B; Neoh, K G; Ting, Y P; Kang, E T

2009-01-01

A novel surface modification technique was developed to provide a copper nickel alloy (M) surface with bactericidal and anticorrosion properties for inhibiting biocorrosion. 4-(chloromethyl)-phenyl tricholorosilane (CTS) was first coupled to the hydroxylated alloy surface to form a compact silane layer, as well as to confer the surface with chloromethyl functional groups. The latter allowed the coupling of 4-vinylpyridine (4VP) to generate the M-CTS-4VP surface with biocidal functionality. Subsequent surface graft polymerization of 4VP, in the presence of benzoyl peroxide (BPO) initiator, from the M-CTS-4VP surface produced the poly(4-vinylpyridine) (P(4VP)) grafted surface, or the M-CTS-P(4VP) surface. The pyridine nitrogen moieties on the M-CTS-P(4VP) surface were quaternized with hexylbromide to produce a high concentration of quaternary ammonium groups. Each surface functionalization step was ascertained by X-ray photoelectron spectroscopy (XPS) and static water contact angle measurements. The alloy with surface-quaternized pyridinium cation groups (N+) exhibited good bactericidal efficiency in a Desulfovibrio desulfuricans-inoculated seawater-based modified Barr's medium, as indicated by viable cell counts and fluorescence microscopy (FM) images of the surface. The anticorrosion capability of the organic layers was verified by the polarization curve and electrochemical impedance spectroscopy (EIS) measurements. In comparison, the pristine (surface hydroxylated) Cu-Ni alloy was found to be readily susceptible to biocorrosion under the same environment.

Alloying effect of copper on the corrosion properties of low-alloy steel for flue gas desulfurization system

NASA Astrophysics Data System (ADS)

Kim, Seon-Hong; Park, Sun-Ah; Kim, Jung-Gu; Shin, Kee-Sam; He, Yinsheng

2015-03-01

The alloying effect of Cu for a flue gas desulfurization materials was investigated using the electrochemical methods in the modified green death solution and the surface analyses. The test results demonstrated that the densely formed rust layer with high metallic Cu content improves the corrosion resistance of Cu-containing steel in the flue gas desulfurization (FGD) environment. The rust layer on the surface of the 0.02 wt% Cu steel, which has an insufficient Cu content, was less protective than others. The 0.05 wt% Cu steel represented the highest corrosion resistance due to the formation of the densely formed rust layer with optimum Cu content. Because the free standing Cu2S precipitates had the insoluble characteristic in highly acidic solution, it produced the relatively porous Cu-enriched layer on the 0.08 wt% Cu steel surface. From these phenomena, the corrosion resistance of specimen decreased as the Cu content of specimen increased from 0.05 wt% to 0.08 wt%.

Generation of alkali-free and high-proton concentration layer in a soda lime glass using non-contact corona discharge

NASA Astrophysics Data System (ADS)

Ikeda, Hiroshi; Sakai, Daisuke; Funatsu, Shiro; Yamamoto, Kiyoshi; Suzuki, Toshio; Harada, Kenji; Nishii, Junji

2013-08-01

Formation mechanisms of alkali-free and high-proton concentration surfaces were investigated for a soda lime glass using a corona discharge treatment under an atmospheric pressure. Protons produced by high DC voltage around an anode needle electrode were incorporated into a sodium ion site in the anode side glass. The sodium ion was swept away to the cathode side as a charge carrier. Then it was discharged. The precipitated sodium was transformed to a Na2CO3 powder when the surface contacted with air. The sodium ion in the glass surface layer of the anode side was replaced completely by protons. The concentration of OH groups in the layer was balanced with the amount of excluded sodium ions. The substitution reaction of sodium ions with protons tends to be saturated according to a square root function of time. The alkali depletion layer formation rate was affected by the large difference in mobility between sodium ions and protons in the glass.

Perceptual transparency from image deformation.

PubMed

Kawabe, Takahiro; Maruya, Kazushi; Nishida, Shin'ya

2015-08-18

Human vision has a remarkable ability to perceive two layers at the same retinal locations, a transparent layer in front of a background surface. Critical image cues to perceptual transparency, studied extensively in the past, are changes in luminance or color that could be caused by light absorptions and reflections by the front layer, but such image changes may not be clearly visible when the front layer consists of a pure transparent material such as water. Our daily experiences with transparent materials of this kind suggest that an alternative potential cue of visual transparency is image deformations of a background pattern caused by light refraction. Although previous studies have indicated that these image deformations, at least static ones, play little role in perceptual transparency, here we show that dynamic image deformations of the background pattern, which could be produced by light refraction on a moving liquid's surface, can produce a vivid impression of a transparent liquid layer without the aid of any other visual cues as to the presence of a transparent layer. Furthermore, a transparent liquid layer perceptually emerges even from a randomly generated dynamic image deformation as long as it is similar to real liquid deformations in its spatiotemporal frequency profile. Our findings indicate that the brain can perceptually infer the presence of "invisible" transparent liquids by analyzing the spatiotemporal structure of dynamic image deformation, for which it uses a relatively simple computation that does not require high-level knowledge about the detailed physics of liquid deformation.

Thin layer imaging process for microlithography using radiation at strongly attenuated wavelengths

DOEpatents

Wheeler, David R.

2004-01-06

A method for patterning of resist surfaces which is particularly advantageous for systems having low photon flux and highly energetic, strongly attenuated radiation. A thin imaging layer is created with uniform silicon distribution in a bilayer format. An image is formed by exposing selected regions of the silylated imaging layer to radiation. The radiation incident upon the silyliated resist material results in acid generation which either catalyzes cleavage of Si--O bonds to produce moieties that are volatile enough to be driven off in a post exposure bake step or produces a resist material where the exposed portions of the imaging layer are soluble in a basic solution, thereby desilylating the exposed areas of the imaging layer. The process is self limiting due to the limited quantity of silyl groups within each region of the pattern. Following the post exposure bake step, an etching step, generally an oxygen plasma etch, removes the resist material from the de-silylated areas of the imaging layer.

Layered Model for Radiation-Induced Chemical Evolution of Icy Surface Composition and Dynamics on Kuiper Belt and Oort Cloud Bodies

NASA Technical Reports Server (NTRS)

Cooper, John F.; Richardson, John D.

2010-01-01

The diversity of albedos and surface colors on observed Kuiper Belt and Inner Oort Cloud objects remains to be explained in terms of competition between primordial intrinsic versus exogenic drivers of surface and near-surface evolution. Earlier models have attempted without success to attribute this diversity to the relations between surface radiolysis from cosmic ray irradiation and gardening by meteoritic impacts. A more flexible approach considers the different depth-dependent radiation profiles produced by low-energy plasma, suprathermal, and maximally penetrating charged particles of the heliospheric and local interstellar radiation environment. Generally red objects of the dynamically cold (low inclination, circular orbit) Classical Kuiper Belt might be accounted for from erosive effects of plasma ions and reddening effects of high energy cosmic ray ions, while suprathermal keV-MeV ions could alternatively produce more color neutral surfaces. The deepest layer of more pristine ice can be brought to the surface from meter to kilometer depths by larger impact events and potentially by cryovolcanic activity. The bright surfaces of some larger objects, e.g. Eris, suggest ongoing resurfacing activity. Cycles of atmospheric formation and surface freezeout can further account for temporal variation as observed on Pluto. The diversity of causative processes must therefore be understood to account for observationally apparent diversities of the object surfaces.

Composite oxygen transport membrane

DOEpatents

Lu, Zigui; Plonczak, Pawel J.; Lane, Jonathan A.

2016-11-08

A method is described of producing a composite oxygen ion membrane and a composite oxygen ion membrane in which a porous fuel oxidation layer and a dense separation layer and optionally, a porous surface exchange layer are formed on a porous support from mixtures of (Ln.sub.1-xA.sub.x).sub.wCr.sub.1-yB.sub.yO.sub.3-.delta. and a doped zirconia. Preferred materials are (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.7Fe.sub.0.3O.sub.3-.delta. for the porous fuel oxidation layer, (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.5Fe.sub.0.5O.sub.3-.delta. for the dense separation layer, and (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.3Fe.sub.0.7O.sub.3-.delta. for the porous surface exchange layer. Firing the said fuel activation and separation layers in nitrogen atmosphere unexpectedly allows the separation layer to sinter into a fully densified mass.

AcmB Is an S-Layer-Associated β-N-Acetylglucosaminidase and Functional Autolysin in Lactobacillus acidophilus NCFM

PubMed Central

Johnson, Brant R.

2016-01-01

ABSTRACT Autolysins, also known as peptidoglycan hydrolases, are enzymes that hydrolyze specific bonds within bacterial cell wall peptidoglycan during cell division and daughter cell separation. Within the genome of Lactobacillus acidophilus NCFM, there are 11 genes encoding proteins with peptidoglycan hydrolase catalytic domains, 9 of which are predicted to be functional. Notably, 5 of the 9 putative autolysins in L. acidophilus NCFM are S-layer-associated proteins (SLAPs) noncovalently colocalized along with the surface (S)-layer at the cell surface. One of these SLAPs, AcmB, a β-N-acetylglucosaminidase encoded by the gene lba0176 (acmB), was selected for functional analysis. In silico analysis revealed that acmB orthologs are found exclusively in S-layer- forming species of Lactobacillus. Chromosomal deletion of acmB resulted in aberrant cell division, autolysis, and autoaggregation. Complementation of acmB in the ΔacmB mutant restored the wild-type phenotype, confirming the role of this SLAP in cell division. The absence of AcmB within the exoproteome had a pleiotropic effect on the extracellular proteins covalently and noncovalently bound to the peptidoglycan, which likely led to the observed decrease in the binding capacity of the ΔacmB strain for mucin and extracellular matrices fibronectin, laminin, and collagen in vitro. These data suggest a functional association between the S-layer and the multiple autolysins noncovalently colocalized at the cell surface of L. acidophilus NCFM and other S-layer-producing Lactobacillus species. IMPORTANCE Lactobacillus acidophilus is one of the most widely used probiotic microbes incorporated in many dairy foods and dietary supplements. This organism produces a surface (S)-layer, which is a self-assembling crystalline array found as the outermost layer of the cell wall. The S-layer, along with colocalized associated proteins, is an important mediator of probiotic activity through intestinal adhesion and modulation of the mucosal immune system. However, there is still a dearth of information regarding the basic cellular and evolutionary function of S-layers. Here, we demonstrate that multiple autolysins, responsible for breaking down the cell wall during cell division, are associated with the S-layer. Deletion of the gene encoding one of these S-layer-associated autolysins confirmed its autolytic role and resulted in reduced binding capacity to mucin and intestinal extracellular matrices. These data suggest a functional association between the S-layer and autolytic activity through the extracellular presentation of autolysins. PMID:27422832

AcmB Is an S-Layer-Associated β-N-Acetylglucosaminidase and Functional Autolysin in Lactobacillus acidophilus NCFM.

PubMed

Johnson, Brant R; Klaenhammer, Todd R

2016-09-15

Autolysins, also known as peptidoglycan hydrolases, are enzymes that hydrolyze specific bonds within bacterial cell wall peptidoglycan during cell division and daughter cell separation. Within the genome of Lactobacillus acidophilus NCFM, there are 11 genes encoding proteins with peptidoglycan hydrolase catalytic domains, 9 of which are predicted to be functional. Notably, 5 of the 9 putative autolysins in L. acidophilus NCFM are S-layer-associated proteins (SLAPs) noncovalently colocalized along with the surface (S)-layer at the cell surface. One of these SLAPs, AcmB, a β-N-acetylglucosaminidase encoded by the gene lba0176 (acmB), was selected for functional analysis. In silico analysis revealed that acmB orthologs are found exclusively in S-layer- forming species of Lactobacillus Chromosomal deletion of acmB resulted in aberrant cell division, autolysis, and autoaggregation. Complementation of acmB in the ΔacmB mutant restored the wild-type phenotype, confirming the role of this SLAP in cell division. The absence of AcmB within the exoproteome had a pleiotropic effect on the extracellular proteins covalently and noncovalently bound to the peptidoglycan, which likely led to the observed decrease in the binding capacity of the ΔacmB strain for mucin and extracellular matrices fibronectin, laminin, and collagen in vitro These data suggest a functional association between the S-layer and the multiple autolysins noncovalently colocalized at the cell surface of L. acidophilus NCFM and other S-layer-producing Lactobacillus species. Lactobacillus acidophilus is one of the most widely used probiotic microbes incorporated in many dairy foods and dietary supplements. This organism produces a surface (S)-layer, which is a self-assembling crystalline array found as the outermost layer of the cell wall. The S-layer, along with colocalized associated proteins, is an important mediator of probiotic activity through intestinal adhesion and modulation of the mucosal immune system. However, there is still a dearth of information regarding the basic cellular and evolutionary function of S-layers. Here, we demonstrate that multiple autolysins, responsible for breaking down the cell wall during cell division, are associated with the S-layer. Deletion of the gene encoding one of these S-layer-associated autolysins confirmed its autolytic role and resulted in reduced binding capacity to mucin and intestinal extracellular matrices. These data suggest a functional association between the S-layer and autolytic activity through the extracellular presentation of autolysins. Copyright © 2016 Johnson and Klaenhammer.

Study of the properties of flux cored wire of Fe-C-Si-Mn-Cr-Mo-Ni-V-Co system for the strengthening of nodes and parts of equipment used in the mineral mining

NASA Astrophysics Data System (ADS)

Gusev, A. I.; Kozyrev, N. A.; Usoltsev, A. A.; Kryukov, R. E.; Osetkovsky, I. V.

2017-09-01

The effect of the introduction of vanadium and cobalt into the charge of the powder surfacing wire of Fe-C-Si-Mn-Cr-Mo-Ni system is studied. In the laboratory conditions, the samples of flux cored wires were produced. The surfacing made by the prepared wire was produced under the flux AN-26C, on the plates of steel St3 in 6 layers with the help of ASAW-1250 welding tractor. Reduction of carbon content in the deposited layer to 0.19-0.2% with simultaneous change in the content of chromium, nickel, molybdenum and other elements present in it contributes to the enlargement of the martensite needles and the increase in the size of the former austenite grain. The obtained dependences of hardness of the deposited layer and its wear resistance on the mass fraction of elements, included in the composition of powder wires of the proposed system, can be used to predict the hardness of the welded layer and its wear resistance under different operating conditions for mining equipment and coal mining equipment.

Experimental Study of Hypersonic Inflatable Aerodynamic Decelerator (HIAD) Aeroshell with Axisymmetric Surface Deflection Patterns

NASA Technical Reports Server (NTRS)

Hollis, Brian R.; Hollingsworth, Kevin E.

2017-01-01

A wind tunnel test program was conducted to obtain aeroheating environment data on Hypersonic Inflatable Aerodynamic Decelerator aeroshells with flexible thermal protection systems. Data were obtained on a set of rigid wind tunnel models with surface deflection patterns of various heights that simulated a range of potential in-flight aeroshell deformations. Wind tunnel testing was conducted at Mach 6 at unit Reynolds numbers from 2.1 × 10(exp 6)/ft to 8.3 × 10(exp 6)/ft and angles of attack from 0 deg to 18 deg. Boundary-layer transition onset and global surface heating distribution measurements were performed using phosphor thermography and flow field images were obtained through schlieren photography. Surface deflections were found to both promote early transition of the boundary layer and to augment heating levels for both laminar and turbulent flows. A complimentary computational flow field study was also performed to provide heating predictions for comparison with the measurements as well as boundary layer flow field properties for use in correlating the data. Correlations of the wind tunnel data were developed to predict deflection effects on boundary layer transition and surface heating and were applied to both the wind tunnel test conditions and to the trajectory of NASA's successful IRVE-3 flight test. In general, the correlations produced at least qualitative agreement with the wind tunnel data, although the heating levels were underpredicted for some of the larger surface deflections. For the flight conditions, the correlations suggested that peak heating levels on the leeward side conical flank of the IRVE-3 vehicle may have exceeded those at nose for times late in the trajectory after the peak heating time point. However, the flight estimates were based on a conservative assumption of surface deflection magnitude (i.e., larger) than likely was produced in flight.

Observation of Electron-Beam-Induced Phase Evolution Mimicking the Effect of the Charge–Discharge Cycle in Li-Rich Layered Cathode Materials Used for Li Ion Batteries

DOE PAGES

Lu, Ping; Yan, Pengfei; Romero, Eric; ...

2015-01-27

Capacity loss, and voltage decrease upon electrochemical charge-discharge cycling observed in lithium-rich layered cathode oxides (Li[Li xMn yTM 1-x-y]O 2, TM = Ni, Co or Fe) have recently been attributed to the formation of a surface reconstructed layer (SRL) that evolves from a thin (<2 nm), defect spinel layer upon the first charge, to a relatively thick (~5nm), spinel or rock-salt layer upon continuous charge-discharge cycling. Here we report observations of a SRL and structural evolution of the SRL on the Li[Li 0.2Ni 0.2Mn 0.6]O 2 (LNMO) particles, which are identical to those reported due to the charge-discharge cycle butmore » are a result of electron-beam irradiation during scanning transmission electron microscopy (STEM) imaging. Sensitivity of the lithium-rich layered oxides to high-energy electrons leads to the formation of thin, defect spinel layer on surfaces of the particles when exposed to a 200kV electron beam for as little as 30 seconds under normal high-resolution STEM imaging conditions. Further electron irradiation produces a thicker layer of the spinel phase, ultimately producing a rock-salt layer at a higher electron exposure. Atomic-scale chemical mapping by electron dispersive X-ray spectroscopy in STEM indicates the electron-beam-induced SRL formation on LNMO is accomplished by migration of the transition metal ions to the Li sites without breaking down the lattice. The observation through this study provides an insight for understanding the mechanism of forming the SRL and also possibly a mean to study structural evolution in the Li-rich layered oxides without involving the electrochemistry.« less

Thunder-induced ground motions: 2. Site characterization

NASA Astrophysics Data System (ADS)

Lin, Ting-L.; Langston, Charles A.

2009-04-01

Thunder-induced ground motion, near-surface refraction, and Rayleigh wave dispersion measurements were used to constrain near-surface velocity structure at an unconsolidated sediment site. We employed near-surface seismic refraction measurements to first define ranges for site structure parameters. Air-coupled and hammer-generated Rayleigh wave dispersion curves were used to further constrain the site structure by a grid search technique. The acoustic-to-seismic coupling is modeled as an incident plane P wave in a fluid half-space impinging into a solid layered half-space. We found that the infrasound-induced ground motions constrained substrate velocities and the average thickness and velocities of the near-surface layer. The addition of higher-frequency near-surface Rayleigh waves produced tighter constraints on the near-surface velocities. This suggests that natural or controlled airborne pressure sources can be used to investigate the near-surface site structures for earthquake shaking hazard studies.

Solar cells based on electrodeposited thin films of ZnS, CdS, CdSSe and CdTe

NASA Astrophysics Data System (ADS)

Weerasinghe, Ajith R.

The motivations of this research were to produce increased efficiency and low-cost solar cells. The production efficiency of Si solar cells has almost reached their theoretical limit, and reducing the manufacturing cost of Si solar cells is difficult to achieve due to the high-energy usage in material purifying and processing stages. Due to the low usage of materials and input energy, thin film solar cells have the potential to reduce the costs. CdS/CdTe thin film solar cells are already the cheapest on $/W basis. The cost of CdTe solar cells can be further reduced if all the semiconducting layers are fabricated using the electrodeposition (ED) method. ED method is scalable, low in the usage of energy and raw materials. These benefits lead to the cost effective production of semiconductors. The conventional method of fabricating CdS layers produces Cd containing waste solutions routinely, which adds to the cost of solar cells.ZnS, CdS and CdS(i-X)Sex buffer and window layers and CdTe absorber layers have been successfully electrodeposited and explored under this research investigation. These layers were fully characterised using complementary techniques to evaluate the material properties. Photoelectrochemical (PEC) studies, optical absorption, X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, atomic force microscopy (AFM) and Raman spectroscopy were utilised to evaluate the material properties of these solid thin film layers. ZnS and CdS thin film layers were electrodeposited from Na-free chemical precursors to avoid the group I element (Na) to reduce deterioration of CdTe devices. Deposition parameters such as, growth substrates, temperature, pH, growth cathodic voltage, stirring rate, time and chemical concentrations were identified to fabricate the above semiconductors. To further optimise these layers, a heat treatment process specific to the material was developed. In addition, the deposition parameters of CdTe layers were further optimised. This research programme has demonstrated that electrodeposited ZnS, CdS and CdTe thin film layers have material characteristics comparable with those of the materials reported in the literature and can be used in thin film solar cell devices. Furthermore, the electrolytes were used for up to two years, reducing the wastage even further, in comparison to other fabrication methods, such as chemical bath deposition. Several large-area semiconducting layers were successfully fabricated to test the scalability of the method. Nano-rods perpendicular to the glass/FTO surface with gaps among grains in CdS layers were observed. In order to reduce the possible pinholes due the gaps, a deposition of a semiconducting layer to cover completely the substrate was investigated. CdS(i-X)Sex layers were investigated to produce a layer-by-layer deposition of the material. However it was observed the surface morphology of CdS(j.X)Sex is a function of the growth parameters which produced nano-wires, nano-tubes and nano-sheets. This is the first recording of this effect for a low temperature deposition method, minimising the cost of producing this highly photosensitive material for use in various nano technology applications.The basic structure experimented was glass/conducting-glass/buffer layer/window material/absorber material/metal. By utilising all the semiconducting layers developed, several solar cell device structures were designed, fabricated and tested. This included a novel all-electrodeposited multi-layer graded bandgap device, to enhance the absorption of solar photons. The device efficiencies varied from batch to batch, and efficiencies in the range (3-7)% were observed. The variations in chemical concentrations, surface states and the presence of pin-hole defects in CdS were the main reasons for the range of efficiencies obtained. In the future work section, ways to avoid these variations and to increase efficiencies are identified and presented.

Geo-material surface modification of microchips using layer-by-layer (LbL) assembly for subsurface energy and environmental applications.

PubMed

Zhang, Y Q; Sanati-Nezhad, A; Hejazi, S H

2018-01-16

A key constraint in the application of microfluidic technology to subsurface flow and transport processes is the surface discrepancy between microchips and the actual rocks/soils. This research employs a novel layer-by-layer (LbL) assembly technology to produce rock-forming mineral coatings on microchip surfaces. The outcome of the work is a series of 'surface-mimetic micro-reservoirs (SMMR)' that represent multi-scales and multi-types of natural rocks/soils. For demonstration, the clay pores of sandstones and mudrocks are reconstructed by representatively coating montmorillonite and kaolinite in polydimethylsiloxane (PDMS) microchips in a wide range of channel sizes (width of 10-250 μm, depth of 40-100 μm) and on glass substrates. The morphological and structural properties of mineral coatings are characterized using a scanning electron microscope (SEM), optical microscope and profilometer. The coating stability is tested by dynamic flooding experiments. The surface wettability is characterized by measuring mineral oil-water contact angles. The results demonstrate the formation of nano- to micro-scale, fully-covered and stable mineral surfaces with varying wetting properties. There is an opportunity to use this work in the development of microfluidic technology-based applications for subsurface energy and environmental research.

Solid state radiative heat pump

DOEpatents

Berdahl, P.H.

1984-09-28

A solid state radiative heat pump operable at room temperature (300 K) utilizes a semiconductor having a gap energy in the range of 0.03-0.25 eV and operated reversibly to produce an excess or deficit of change carriers as compared equilibrium. In one form of the invention an infrared semiconductor photodiode is used, with forward or reverse bias, to emit an excess or deficit of infrared radiation. In another form of the invention, a homogenous semiconductor is subjected to orthogonal magnetic and electric fields to emit an excess or deficit of infrared radiation. Three methods of enhancing transmission of radiation the active surface of the semiconductor are disclosed. In one method, an anti-refection layer is coated into the active surface of the semiconductor, the anti-reflection layer having an index of refraction equal to the square root of that of the semiconductor. In the second method, a passive layer is speaced trom the active surface of the semiconductor by a submicron vacuum gap, the passive layer having an index of refractive equal to that of the semiconductor. In the third method, a coupler with a paraboloid reflecting surface surface is in contact with the active surface of the semiconductor, the coupler having an index of refraction about the same as that of the semiconductor.

Plasma carburizing with surface micro-melting

NASA Astrophysics Data System (ADS)

Balanovsky, A. E.; Grechneva, M. V.; Van Huy, Vu; Ponomarev, B. B.

2018-03-01

This paper presents carburizing the surface of 20 low carbon steel using electric arc and graphite prior. A carbon black solution was prepared with graphite powder and sodium silicate in water. A detailed analysis of the phase structure and the distribution profile of the sample hardness after plasma treatment were given. The hardened layer consists of three different zones: 1 – the cemented layer (thin white zone) on the surface, 2 – heat-affected zone (darkly etching structure), 3 – the base metal. The experimental result shows that the various microstructures and micro-hardness profiles were produced depending on the type of graphite coating (percentage of liquid glass) and processing parameters. The experiment proved that the optimum content of liquid glass in graphite coating is 50–87.5%. If the amount of liquid glass is less than 50%, adhesion to metal is insufficient. If liquid glass content is more than 87.5%, carburization of a metal surface does not occur. A mixture of the eutectic lamellar structure, martensite and austenite was obtained by using graphite prior with 67% sodium silicate and the levels of the hardness layer increased to around 1000 HV. The thickness of the cemented layer formed on the surface was around 200 μm. It is hoped that this plasma surface carburizing treatment could improve the tribological resistance properties.

Epitaxial ZnO/LiNbO{sub 3}/ZnO stacked layer waveguide for application to thin-film Pockels sensors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akazawa, Housei, E-mail: akazawa.housei@lab.ntt.co.jp; Fukuda, Hiroshi

We produced slab waveguides consisting of a LiNbO{sub 3} (LN) core layer that was sandwiched with Al-doped ZnO cladding layers. The ZnO/LN/ZnO stacked layers were grown on sapphire C-planes by electron cyclotron resonance (ECR) plasma sputtering and were subjected to structural, electrical, and optical characterizations. X-ray diffraction confirmed that the ZnO and LN layers were epitaxial without containing misoriented crystallites. The presence of 60°-rotational variants of ZnO and LN crystalline domains were identified from X-ray pole figures. Cross-sectional transmission electron microscopy images revealed a c-axis orientated columnar texture for LN crystals, which ensured operation as electro-optic sensors based on opticalmore » anisotropy along longitudinal and transversal directions. The interfacial roughness between the LN core and ZnO bottom layers as well as that between the ZnO top and the LN core layers was less than 20 nm, which agreed with surface images observed with atomic force microscopy. Outgrowth of triangular LN crystalline domains produced large roughness at the LN film surface. The RMS roughness of the LN film surface was twice that of the same structure grown on sapphire A-planes. Vertical optical transmittance of the stacked films was higher than 85% within the visible and infrared wavelength range. Following the approach adopted by Teng and Man [Appl. Phys. Lett. 56, 1734 (1990)], ac Pockels coefficients of r{sub 33} = 24-28 pm/V were derived for c-axis oriented LN films grown on low-resistive Si substrates. Light propagation within a ZnO/LN/ZnO slab waveguide as well as within a ZnO single layer waveguide was confirmed. The birefringence of these waveguides was 0.11 for the former and 0.05 for the latter.« less

Conductive aluminum line formation on aluminum nitride surface by infrared nanosecond laser

NASA Astrophysics Data System (ADS)

Kozioł, Paweł E.; Antończak, Arkadiusz J.; Szymczyk, Patrycja; Stępak, Bogusz; Abramski, Krzysztof M.

2013-12-01

In this paper the fabrication of conductive aluminum paths on AlN ceramic's surface due to the interaction of laser radiation Nd:YAG (1.064 μm) is presented. The metallization process produces an appropriate power value on the ceramics surface to ensure the correct temperature (2200 °C) for which aluminum and nitrogen bonds are broken. Studies have been undertaken on creating low-ohmic structures depending on the parameters such as radiation power, scanning speed, the coverage of subsequent pulses and the environmental impact of the process (air, nitrogen, argon). Furthermore, with regards to the application of this method, it was significant to determine the thickness of the functional layer. A structure of the resistivity of ρ = 0.64 × 10-6 Ω m and aluminum layer thickness of 10 μm was achieved for the process carried out on the inert gas, argon. In addition, a quantitative analysis of nitrogen and aluminum for laser-treated structures was conducted. The performed tests confirmed that the highest amount of aluminum was produced on the surface treated by laser radiation in the environment of the process gas, argon.

Heat flux estimates over vegetation derived using radiometric surface temperatures and a boundary layer model in comparison with sodar-derived values. M.S. Thesis; [Rock Springs Agricultural Research Center, Pennsylvania

NASA Technical Reports Server (NTRS)

Cooper, J. N. (Principal Investigator)

1981-01-01

An attempt was made to validate a method that uses radiometric surface temperatures and a boundary layer model to estimate surface energy budgets and characteristics. Surface temperatures from a hand-held radiometer and sodar data were collected simultaneously on seven days between mid-July and mid-October 1980. The comparison of the RDMS and sodar heat fluxes proved disappointing. Free convection conditions, required to produce sodar-derived heat fluxes, were inhibited by a terrain-induced low level inversion. Only three out of seven cases produced meaningful sodar heat fluxes. Of those three cases, one had good agreement and the other two had sodar heat fluxes 15 to 45 w/sq m lower than the RDMS values. Since the RDMS method is relatively untested, it was impossible to conclusively determine its validity from the results. There was evidence that the true heat flux was not underestimated by the RDMS, so it could be concluded that the Bowen ratios over well-watered vegetation were likely to be quite small.

Terahertz acoustic phonon detection from a compact surface layer of spherical nanoparticles powder mixture of aluminum, alumina and multi-walled carbon nanotube

NASA Astrophysics Data System (ADS)

Abouelsayed, A.; Ebrahim, M. R.; El hotaby, W.; Hassan, S. A.; Al-Ashkar, Emad

2017-10-01

We present terahertz spectroscopy study on spherical nanoparticles powder mixture of aluminum, alumina, and MWCNTs induced by surface mechanical attrition treatment (SMAT) of aluminum substrates. Surface alloying of AL, Al2O3 0.95% and MWCNTs 0.05% powder mixture was produced during SMAT process, where a compact surface layer of about 200 μm due to ball bombardment was produced from the mixture. Al2O3 alumina powder played a significant role in MWCNTs distribution on surface, those were held in deformation surface cites of micro-cavities due to SMAT process of Al. The benefits are the effects on resulted optical properties of the surface studied at the terahertz frequency range due to electrical isolation confinement effects and electronic resonance disturbances exerted on Al electronic resonance at the same range of frequencies. THz acoustic phonon around 0.53-0.6 THz (17-20 cm-1) were observed at ambient conditions for the spherical nanoparticles powder mixture of Al, Al2O3 and MWCNTs. These results suggested that the presence of Al2O3 and MWCNTs during SMAT process leads to the optically detection of such acoustic phonon in the THz frequency range.

Doping control by ALD surface functionalization

DOEpatents

Elam, Jeffrey W.; Yanguas-Gil, Angel

2015-02-10

Systems and methods for producing a material of desired thickness. Deposition techniques such as atomic layer deposition are alter to control the thickness of deposited material. A funtionalization species inhibits the deposition reaction.

Modelling the effect of race surface and racehorse limb parameters on in silico fetlock motion and propensity for injury.

PubMed

Symons, J E; Hawkins, D A; Fyhrie, D P; Upadhyaya, S K; Stover, S M

2017-09-01

The metacarpophalangeal joint (fetlock) is the most commonly affected site of racehorse injury, with multiple observed pathologies consistent with extreme fetlock dorsiflexion. Race surface mechanics affect musculoskeletal structure loading and injury risk because surface forces applied to the hoof affect limb motions. Race surface mechanics are a function of controllable factors. Thus, race surface design has the potential to reduce the incidence of musculoskeletal injury through modulation of limb motions. However, the relationship between race surface mechanics and racehorse limb motions is unknown. To determine the effect of changing race surface and racehorse limb model parameters on distal limb motions. Sensitivity analysis of in silico fetlock motion to changes in race surface and racehorse limb parameters using a validated, integrated racehorse and race surface computational model. Fetlock motions were determined during gallop stance from simulations on virtual surfaces with differing average vertical stiffness, upper layer (e.g. cushion) depth and linear stiffness, horizontal friction, tendon and ligament mechanics, as well as fetlock position at heel strike. Upper layer depth produced the greatest change in fetlock motion, with lesser depths yielding greater fetlock dorsiflexion. Lesser fetlock changes were observed for changes in lower layer (e.g. base or pad) mechanics (nonlinear), as well as palmar ligament and tendon stiffness. Horizontal friction and fetlock position contributed less than 1° change in fetlock motion. Simulated fetlock motions are specific to one horse's anatomy reflected in the computational model. Anatomical differences among horses may affect the magnitude of limb flexion, but will likely have similar limb motion responses to varied surface mechanics. Race surface parameters affected by maintenance produced greater changes in fetlock motion than other parameters studied. Simulations can provide evidence to inform race surface design and management to reduce the incidence of injury. © 2017 EVJ Ltd.

Aligned carbon nanotube, graphene and graphite oxide thin films via substrate-directed rapid interfacial deposition

NASA Astrophysics Data System (ADS)

D'Arcy, Julio M.; Tran, Henry D.; Stieg, Adam Z.; Gimzewski, James K.; Kaner, Richard B.

2012-05-01

A procedure for depositing thin films of carbon nanostructures is described that overcomes the limitations typically associated with solution based methods. Transparent and conductively continuous carbon coatings can be grown on virtually any type of substrate within seconds. Interfacial surface tension gradients result in directional fluid flow and film spreading at the water/oil interface. Transparent films of carbon nanostructures are produced including aligned ropes of single-walled carbon nanotubes and assemblies of single sheets of chemically converted graphene and graphite oxide. Process scale-up, layer-by-layer deposition, and a simple method for coating non-activated hydrophobic surfaces are demonstrated.A procedure for depositing thin films of carbon nanostructures is described that overcomes the limitations typically associated with solution based methods. Transparent and conductively continuous carbon coatings can be grown on virtually any type of substrate within seconds. Interfacial surface tension gradients result in directional fluid flow and film spreading at the water/oil interface. Transparent films of carbon nanostructures are produced including aligned ropes of single-walled carbon nanotubes and assemblies of single sheets of chemically converted graphene and graphite oxide. Process scale-up, layer-by-layer deposition, and a simple method for coating non-activated hydrophobic surfaces are demonstrated. Electronic supplementary information (ESI) available: Droplet coalescence, catenoid formation, mechanism of film growth, scanning electron micrographs showing carbon nanotube alignment, flexible transparent films of SWCNTs, AFM images of a chemically converted graphene film, and SEM images of SWCNT free-standing thin films. See DOI: 10.1039/c2nr00010e

Mechanisms and Methods for Selective Wavelength Filtering

NASA Technical Reports Server (NTRS)

Tuma, Margaret (Inventor); Brown, Thomas G. (Inventor); Gruhlke, Russell (Inventor)

2007-01-01

An optical filter includes a dielectric waveguide layer, supporting waveguide modes at specific wavelengths and receiving incident light, a corrugated film layer, composed of one of a metal and a semiconductor and positioned adjacent to a second surface of the waveguide layer and a sensor layer, wherein the sensor layer is capable of absorbing optical energy and generating a corresponding electrical signal. The metal film layer supports a plurality of plasmons, the plurality of plasmons producing a first field and is excited by a transverse mode of the waveguide modes at a wavelength interval. The first field penetrates the sensor layer and the sensor layer generates an electrical signal corresponding to an intensity of received incident light within the wavelength interval.

Multi-layer carbon-based coatings for field emission

DOEpatents

Sullivan, J.P.; Friedmann, T.A.

1998-10-13

A multi-layer resistive carbon film field emitter device for cold cathode field emission applications is disclosed. The multi-layered film of the present invention consists of at least two layers of a conductive carbon material, preferably amorphous-tetrahedrally coordinated carbon, where the resistivities of adjacent layers differ. For electron emission from the surface, the preferred structure can be a top layer having a lower resistivity than the bottom layer. For edge emitting structures, the preferred structure of the film can be a plurality of carbon layers, where adjacent layers have different resistivities. Through selection of deposition conditions, including the energy of the depositing carbon species, the presence or absence of certain elements such as H, N, inert gases or boron, carbon layers having desired resistivities can be produced. 8 figs.

Reliable solution processed planar perovskite hybrid solar cells with large-area uniformity by chloroform soaking and spin rinsing induced surface precipitation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chern, Yann-Cherng; Wu, Hung-Ruei; Chen, Yen-Chu

2015-08-15

A solvent soaking and rinsing method, in which the solvent was allowed to soak all over the surface followed by a spinning for solvent draining, was found to produce perovskite layers with high uniformity on a centimeter scale and with much improved reliability. Besides the enhanced crystallinity and surface morphology due to the rinsing induced surface precipitation that constrains the grain growth underneath in the precursor films, large-area uniformity with film thickness determined exclusively by the rotational speed of rinsing spinning for solvent draining was observed. With chloroform as rinsing solvent, highly uniform and mirror-like perovskite layers of area asmore » large as 8 cm × 8 cm were produced and highly uniform planar perovskite solar cells with power conversion efficiency of 10.6 ± 0.2% as well as much prolonged lifetime were obtained. The high uniformity and reliability observed with this solvent soaking and rinsing method were ascribed to the low viscosity of chloroform as well as its feasibility of mixing with the solvent used in the precursor solution. Moreover, since the surface precipitation forms before the solvent draining, this solvent soaking and rinsing method may be adapted to spinless process and be compatible with large-area and continuous production. With the large-area uniformity and reliability for the resultant perovskite layers, this chloroform soaking and rinsing approach may thus be promising for the mass production and commercialization of large-area perovskite solar cells.« less

Graphene Nanolayers as a New Method for Bacterial Biofilm Prevention: Preliminary Results.

PubMed

Dybowska-Sarapuk, Łucja; Kotela, Andrzej; Krzemiński, Jakub; Wróblewska, Marta; Marchel, Halina; Romaniec, Magdalena; Łęgosz, Paweł; Jakubowska, Małgorzata

2017-07-01

Biofilms are microbial communities of surface-attached cells embedded in a self-produced extracellular matrix. They have been found to play a role in a wide variety of infections, including catheter-related urinary tract and bloodstream infections, and, therefore remain a significant source of morbidity and mortality among the world's population. Recently, much attention has been devoted to the prevention of biofilm formation on implant surfaces. Nanomaterials such as graphene, characterized by antibacterial activity and low toxicity to human cells, are promising candidates for biomedical applications. This study investigates the antibacterial efficiency of graphene and specially produced graphene decorated with silver nanoparticles, obtained by one of the methods of printed electronics (spray-coating system). These methods are not only economical, but also enable the printing of layers of various thicknesses on different types of materials, including flexible and nonplanar substrates. The aim of the study was to reveal the ability of graphene and graphene-nanosilver layers to prevent the formation of Staphylococcus epidermidis biofilm on the surface of a Foley catheter.

Method to produce large, uniform hollow spherical shells

DOEpatents

Hendricks, C.D.

1983-09-26

The invention is a method to produce large uniform hollow spherical shells by (1) forming uniform size drops of heat decomposable or vaporizable material, (2) evaporating the drops to form dried particles, (3) coating the dried particles with a layer of shell forming material and (4) heating the composite particles to melt the outer layer and to decompose or vaporize the inner particle to form an expanding inner gas bubble. The expanding gas bubble forms the molten outer layer into a shell of relatively large diameter. By cycling the temperature and pressure on the molten shell, nonuniformities in wall thickness can be reduced. The method of the invention is utilized to produce large uniform spherical shells, in the millimeter to centimeter diameter size range, from a variety of materials and of high quality, including sphericity, concentricity and surface smoothness, for use as laser fusion or other inertial confinement fusion targets as well as other applications.

Development of batch producible hot embossing 3D nanostructured surface-enhanced Raman scattering chip technology

NASA Astrophysics Data System (ADS)

Huang, Chu-Yu; Tsai, Ming-Shiuan

2017-09-01

The main purpose of this study is to develop a batch producible hot embossing 3D nanostructured surface-enhanced Raman chip technology for high sensitivity label-free plasticizer detection. This study utilizing the AAO self-assembled uniform nano-hemispherical array barrier layer as a template to create a durable nanostructured nickel mold. With the hot embossing technique and the durable nanostructured nickel mold, we are able to batch produce the 3D Nanostructured Surface-enhanced Raman Scattering Chip with consistent quality. In addition, because of our SERS chip can be fabricated by batch processing, the fabrication cost is low. Therefore, the developed method is very promising to be widespread and extensively used in rapid chemical and biomolecular detection applications.

Surface controlled biomimetic coating of polycaprolactone nanofiber meshes to be used as bone extracellular matrix analogues.

PubMed

Araujo, J V; Martins, A; Leonor, I B; Pinho, E D; Reis, R L; Neves, N M

2008-01-01

The aim of this work was to develop novel electrospun nanofiber meshes coated with a biomimetic calcium phosphate (BCP) layer that mimics the extracellular microenvironment found in the human bone structure. Poly (epsilon-caprolactone) (PCL) was selected because of its well-known medical applications, its biodegradability, biocompatibility and its susceptibility to partial hydrolysis by a straightforward alkaline treatment. The deposition of a calcium phosphate layer, similar to the inorganic phase of bone, on PCL nanofiber meshes was achieved by means of a surface modification. This initial surface modification was followed by treatment with solutions containing calcium and phosphate ions. The process was finished by a posterior immersion in a simulated body fluid (SBF) with nearly 1.5 x the inorganic concentration of the human blood plasma ions. After some optimization work, the best conditions were chosen to perform the biological assays. The influence of the bone-like BCP layer on the viability and adhesion, as well as on the proliferation of human osteoblast-like cells, was assessed. It was shown that PCL nanofiber meshes coated with a BCP layer support and enhance the proliferation of osteoblasts for long culture periods. The attractive properties of the coated structures produced in the present work demonstrated that those materials have potential to be used for applications in bone tissue engineering. This is the first time that nanofiber meshes could be coated with a biomimetic bone-like calcium phosphate layer produced in a way that the original mesh architecture can be fully maintained.

Laser interferometer/Preston tube skin-friction comparison in shock/boundary-layer interaction

NASA Technical Reports Server (NTRS)

Kim, K.-S.; Lee, Y.; Settles, G. S.

1991-01-01

An evaluation is conducted of the accuracy of the 'Preston tube' surface pitot-pressure skin friction measurement method relative to the already proven laser interferometer skin-friction meter in a swept shock wave/turbulent boundary-layer interaction. The Preston tube was used to estimate the total shear-stress distribution in a fin-generated swept shock-wave/turbulent boundary-layer interaction. The Keener-Hopkins calibration method using the isentropic relation to calculate the Preston-tube Mach number produces the best results.

Large Area Atomically Flat Surfaces via Exfoliation of Bulk Bi 2Se 3 Single Crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Melamed, Celeste L.; Ortiz, Brenden R.; Gorai, Prashun

In this paper, we present an exfoliation method that produces cm 2-area atomically flat surfaces from bulk layered single crystals, with broad applications such as for the formation of lateral heterostructures and for use as substrates for van der Waals epitaxy. Single crystals of Bi 2Se 3 were grown using the Bridgman method and examined with X-ray reciprocal space maps, Auger spectroscopy, low-energy electron diffraction, and X-ray photoelectron spectroscopy. An indium-bonding exfoliation technique was developed that produces multiple ~100 um thick atomically flat, macroscopic (>1 cm 2) slabs from each Bi 2Se 3 source crystal. Two-dimensional X-ray diffraction and reciprocalmore » space maps confirm the high crystalline quality of the exfoliated surfaces. Atomic force microscopy reveals that the exfoliated surfaces have an average root-mean-square (RMS) roughness of ~0.04 nm across 400 μm 2 scans and an average terrace width of 70 um between step edges. First-principles calculations reveal exfoliation energies of Bi 2Se 3 and a number of other layered compounds, which demonstrate relevance of our method across the field of 2D materials. While many potential applications exist, excellent lattice matching with the III-V alloy space suggests immediate potential for the use of these exfoliated layered materials as epitaxial substrates for photovoltaic development.« less

Large Area Atomically Flat Surfaces via Exfoliation of Bulk Bi 2Se 3 Single Crystals

DOE PAGES

Melamed, Celeste L.; Ortiz, Brenden R.; Gorai, Prashun; ...

2017-09-12

In this paper, we present an exfoliation method that produces cm 2-area atomically flat surfaces from bulk layered single crystals, with broad applications such as for the formation of lateral heterostructures and for use as substrates for van der Waals epitaxy. Single crystals of Bi 2Se 3 were grown using the Bridgman method and examined with X-ray reciprocal space maps, Auger spectroscopy, low-energy electron diffraction, and X-ray photoelectron spectroscopy. An indium-bonding exfoliation technique was developed that produces multiple ~100 um thick atomically flat, macroscopic (>1 cm 2) slabs from each Bi 2Se 3 source crystal. Two-dimensional X-ray diffraction and reciprocalmore » space maps confirm the high crystalline quality of the exfoliated surfaces. Atomic force microscopy reveals that the exfoliated surfaces have an average root-mean-square (RMS) roughness of ~0.04 nm across 400 μm 2 scans and an average terrace width of 70 um between step edges. First-principles calculations reveal exfoliation energies of Bi 2Se 3 and a number of other layered compounds, which demonstrate relevance of our method across the field of 2D materials. While many potential applications exist, excellent lattice matching with the III-V alloy space suggests immediate potential for the use of these exfoliated layered materials as epitaxial substrates for photovoltaic development.« less

Characterization of surface roughness of laser deposited titanium alloy and copper using AFM

NASA Astrophysics Data System (ADS)

Erinosho, M. F.; Akinlabi, E. T.; Johnson, O. T.

2018-03-01

Laser Metal Deposition (LMD) is the process of using the laser beam of a nozzle to produce a melt pool on a metal surface usually the substrate and metal powder is been deposited into it thereby creating a fusion bond with the substrate to form a new material layer against the force gravity. A good metal laminate is formed when the wettability between the dropping metal powder and the substrate adheres. This paper reports the surface roughness of laser deposited titanium alloy and copper (Ti6Al4V + Cu) using the Atomic Force Microscopy (AFM). This AFM is employed in order to sense the surface and produce different manipulated images using the micro-fabricated mechanical tip under a probe cartridge of high resolution. The process parameters employed during the deposition routine determines the output of the deposit. A careful attention is given to the laser deposited Ti6Al4V + Cu samples under the AFM probe because of their single tracked layers with semi-circular pattern of deposition. This research work can be applicable in the surface modification of laser deposited samples for the marine industry.

Boundary Layer Flow Control with a One Atmosphere Uniform Glow Discharge Surface Plasma

NASA Technical Reports Server (NTRS)

Roth, J. Reece; Sherman, Daniel M.; Wilkinson, Stephen P.

1998-01-01

Low speed wind tunnel data have been acquired for planar panels covered by a uniform, glow-discharge surface plasma in atmospheric pressure air known as the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP). Streamwise and spanwise arrays of flush, plasma-generating surface electrodes have been studied in laminar, transitional, and fully turbulent boundary layer flow. Plasma between symmetric streamwise electrode strips caused large increases in panel drag, whereas asymmetric spanwise electrode configurations produced a significant thrust. Smoke wire flow visualization and mean velocity diagnostics show the primary cause of the phenomena to be a combination of mass transport and vortical structures induced by strong paraelectric ElectroHydroDynamic (EHD) body forces on the flow.

Surface acoustic wave dust deposition monitor

DOEpatents

Fasching, G.E.; Smith, N.S. Jr.

1988-02-12

A system is disclosed for using the attenuation of surface acoustic waves to monitor real time dust deposition rates on surfaces. The system includes a signal generator, a tone-burst generator/amplifier connected to a transmitting transducer for converting electrical signals into acoustic waves. These waves are transmitted through a path defining means adjacent to a layer of dust and then, in turn, transmitted to a receiving transducer for changing the attenuated acoustic wave to electrical signals. The signals representing the attenuated acoustic waves may be amplified and used in a means for analyzing the output signals to produce an output indicative of the dust deposition rates and/or values of dust in the layer. 8 figs.

IPMC paints

NASA Astrophysics Data System (ADS)

Park, Il-Seok; Tiwari, Rashi; Kim, Kwang J.

2008-03-01

In this paper we are reporting a newely developed IPMC fabrication method, "IPMC Paint", which can be directly sprayed onto any complex surface. In order to fabricate the IPMC paint, liquid Nafion TM was used for the ionic conducting polymer instead of the typical film/sheet type Nafion TM. The viscosity of liquid Nafion TM was adjusted by adding Polyvinylpyrrolidone (PVP) to perform spray painting. Modified Nafion was sprayed onto the conducting substrate, Polyfoil TM which acts as base electrode layer. After three times spraying, ionic polymer layer has 45 μm thickness and 10 μm of surface roughness. Sensing tests show that IPMC paint sensor has more sensitivity (+/- 0.06 of producing voltage) than that of the typical IPMC (+/- 0.005 of producing voltage) when dynamic bending with 10 Hz frequency and 1.3 cm of displacement is applied to.

Anodization: a promising nano-modification technique of titanium implants for orthopedic applications.

PubMed

Yao, Chang; Webster, Thomas J

2006-01-01

Anodization is a well-established surface modification technique that produces protective oxide layers on valve metals such as titanium. Many studies have used anodization to produce micro-porous titanium oxide films on implant surfaces for orthopedic applications. An additional hydrothermal treatment has also been used in conjunction with anodization to deposit hydroxyapatite on titanium surfaces; this is in contrast to using traditional plasma spray deposition techniques. Recently, the ability to create nanometer surface structures (e.g., nano-tubular) via anodization of titanium implants in fluorine solutions have intrigued investigators to fabricate nano-scale surface features that mimic the natural bone environment. This paper will present an overview of anodization techniques used to produce micro-porous titanium oxide structures and nano-tubular oxide structures, subsequent properties of these anodized titanium surfaces, and ultimately their in vitro as well as in vivo biological responses pertinent for orthopedic applications. Lastly, this review will emphasize why anodized titanium structures that have nanometer surface features enhance bone forming cell functions.

Terahertz analysis of stratified wall plaster at buildings of cultural importance across Europe

NASA Astrophysics Data System (ADS)

Walker, Gillian C.; Jackson, J. Bianca; Giovannacci, David; Bowen, John W.; Delandes, Bruno; Labaune, Julien; Mourou, Gerard; Menu, Michel; Detalle, Vincent

2013-05-01

Terahertz (THz) radiation is being developed as a tool for the analysis of cultural heritage, and due to recent advances in technology is now available commercially in systems which can be deployed for field analysis. The radiation is capable of penetrating up to one centimetre of wall plaster and is delivered in ultrafast pulses which are reflected from layers within this region. The technique is non-contact, non-invasive and non-destructive. While sub-surface radar is able to penetrate over a metre of wall plaster, producing details of internal structures, infrared and ultraviolet techniques produce information about the surface layers of wall plaster. THz radiation is able to provide information about the interim region of up to approximately one centimetre into the wall surface. Data from Chartres Cathedral, France, Riga Dome Cathedral, Latvia, and Chartreuse du Val de Bénédiction, France is presented each with different research questions. The presence of sub-surface paint layers was expected from documentary evidence, dating to the 13th Century, at Chartres Cathedral. In contrast, at the Riga Dome Cathedral surface painting had been obscured as recently as 1941 during the Russian occupation of Latvia using white lead-based paint. In the 13th Century, wall paintings at the Chapel of the Frescos, Chartreuse du Val de Benediction in Villeneuve les Avignon were constructed using sinopia under-painting on plaster covering uneven stonework.. This paper compares and contrasts the ability of THz radiation to provide information about sub-surface features in churches and Cathedrals across Europe by analysing depth based profiles gained from the reflected signal.

Distributed feedback laser biosensor incorporating a titanium dioxide nanorod surface

NASA Astrophysics Data System (ADS)

Ge, Chun; Lu, Meng; Zhang, Wei; Cunningham, Brian T.

2010-04-01

A dielectric nanorod structure is used to enhance the label-free detection sensitivity of a vertically-emitting distributed feedback laser biosensor (DFBLB). The device is comprised of a replica molded plastic grating that is subsequently coated with a dye-doped polymer layer and a TiO2 nanorod layer produced by the glancing angle deposition technique. The DFBLB emission wavelength is modulated by the adsorption of biomolecules, whose greater dielectric permittivity with respect to the surrounding liquid media will increase the laser wavelength in proportion to the density of surface-adsorbed biomaterial. The nanorod layer provides greater surface area than a solid dielectric thin film, resulting in the ability to incorporate a greater number of molecules. The detection of a monolayer of protein polymer poly (Lys, Phe) is used to demonstrate that a 90 nm TiO2 nanorod structure improves the detection sensitivity by a factor of 6.6 compared to an identical sensor with a nonporous TiO2 surface.

Delay of Turbulent Boundary Layer Detachment by Mechanical Excitation: Application to Rearward-facing Ramp

NASA Technical Reports Server (NTRS)

McKinzie, Daniel J., Jr.

1996-01-01

A vane oscillating about a fixed point at the inlet to a two-dimensional 20 deg rearward-facing ramp proved effective in delaying the detachment of a turbulent boundary layer. Flow-field, surface static pressure, and smoke-wire flow visualization measurements were made. Surface pressure coefficient distributions revealed that two different effects occurred with axial distance along the ramp surface. The surface pressure coefficient varied as a complex function of the vane oscillation frequency and its trailing edge displacement amplitude; that is, it varied as a function of the vane oscillation frequency throughout the entire range of frequencies covered during the test, but it varied over only a limited range of the trailing edge displacement amplitudes covered.The complexity of these findings prompted a detailed investigation, the results of which revealed a combination of phenomena that explain qualitatively how the mechanically generated, periodic, sinusoidal perturbing signal produced by the oscillating vane reacts with the fluid flow to delay the detachment of a turbulent boundary layer experiencing transitory detachment.

Atomically Precise Surface Engineering for Producing Imagers

NASA Technical Reports Server (NTRS)

Nikzad, Shouleh (Inventor); Hoenk, Michael E. (Inventor); Greer, Frank (Inventor); Jones, Todd J. (Inventor)

2015-01-01

High-quality surface coatings, and techniques combining the atomic precision of molecular beam epitaxy and atomic layer deposition, to fabricate such high-quality surface coatings are provided. The coatings made in accordance with the techniques set forth by the invention are shown to be capable of forming silicon CCD detectors that demonstrate world record detector quantum efficiency (>50%) in the near and far ultraviolet (155 nm-300 nm). The surface engineering approaches used demonstrate the robustness of detector performance that is obtained by achieving atomic level precision at all steps in the coating fabrication process. As proof of concept, the characterization, materials, and exemplary devices produced are presented along with a comparison to other approaches.

3D surface topography study of the biofunctionalized nanocrystalline Ti-6Zr-4Nb/Ca-P

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jakubowicz, J., E-mail: jaroslaw.jakubowicz@put.poznan.pl; Adamek, G.; Jurczyk, M.U.

2012-08-15

In this work surface of the sintered Ti-6Zr-4Nb nanocrystalline alloy was electrochemically biofunctionalized. The porous surface was produced by anodic oxidation in 1 M H{sub 3}PO{sub 4} + 2%HF electrolyte at 10 V for 30 min. Next the calcium-phosphate (Ca-P) layer was deposited, onto the formed porous surface, using cathodic potential - 5 V kept for 60 min in 0.042 M Ca(NO{sub 3}){sub 2} + 0.025 M (NH{sub 4}){sub 2}HPO{sub 4} + 0.1 M HCl electrolyte. The deposited Ca-P layer anchored in the pores. The biofunctionalized surface was studied by XRD, SEM and EDS. In vitro tests culture of normalmore » human osteoblast (NHOst) cells showed very good cells proliferation, colonization and multilayering. Using optical profiler, roughness and hybrid 3D surface topography parameters were estimated. Correlation between surface composition, morphology, roughness and biocompatibility results was done. It has been shown by us that surface with appropriate chemical composition and topography, after combined electrochemical anodic and cathodic surface treatment, supports osteoblast adhesion and proliferation. 3D topography measurements using optical profiler play a key role in the biomaterials surface analysis. - Highlights: Black-Right-Pointing-Pointer Nanocrystalline Ti-6Zr-4Nb/Ca-P material was produced for hard tissue implant applications. Black-Right-Pointing-Pointer Calcium-phosphate results in surface biofunctionalization. Black-Right-Pointing-Pointer The biofunctionalized surface shows good in-vitro behavior.« less

Method for producing a hybridization of detector array and integrated circuit for readout

NASA Technical Reports Server (NTRS)

Fossum, Eric R. (Inventor); Grunthaner, Frank J. (Inventor)

1993-01-01

A process is explained for fabricating a detector array in a layer of semiconductor material on one substrate and an integrated readout circuit in a layer of semiconductor material on a separate substrate in order to select semiconductor material for optimum performance of each structure, such as GaAs for the detector array and Si for the integrated readout circuit. The detector array layer is lifted off its substrate, laminated on the metallized surface on the integrated surface, etched with reticulating channels to the surface of the integrated circuit, and provided with interconnections between the detector array pixels and the integrated readout circuit through the channels. The adhesive material for the lamination is selected to be chemically stable to provide electrical and thermal insulation and to provide stress release between the two structures fabricated in semiconductor materials that may have different coefficients of thermal expansion.

Three-Dimensional Porous Particles Composed of Curved, Two-Dimensional, Nano-Sized Layers for Li-Ion Batteries

NASA Technical Reports Server (NTRS)

Yushin, Gleb; Evanoff, Kara; Magasinski, Alexander

2012-01-01

Thin Si films coated on porous 3D particles composed of curved 2D graphene sheets have been synthesized utilizing techniques that allow for tunable properties. Since graphene exhibits specific surface area up to 100 times higher than carbon black or graphite, the deposition of the same mass of Si on graphene is much faster in comparison -- a factor which is important for practical applications. In addition, the distance between graphene layers is tunable and variation in the thickness of the deposited Si film is feasible. Both of these characteristics allow for optimization of the energy and power characteristics. Thicker films will allow higher capacity, but slower rate capabilities. Thinner films will allow more rapid charging, or higher power performance. In this innovation, uniform deposition of Si and C layers on high-surface area graphene produced granules with specific surface area (SSA) of 5 sq. m/g.

An Investigation into the Mechanics of Windblown Dust Entrainment from Nickel Slag Surfaces Resembling Armoured Desert Pavements

NASA Astrophysics Data System (ADS)

Sanderson, Robert Steven

The purpose of this thesis is to investigate the dynamics of PM 10 emission from a nickel slag stockpile that closely resembles a desert pavement in physical characteristics. In the field, it was observed that slag surfaces develop by natural processes into a well-armoured surface over some period of time. The surface then consists of two distinct layers; a surficial armour layer containing only non-erodible gravel and cobble-sized clasts, and an underlying dust-laden layer, which contains a wide size range of slag particles, from clay-sized to cobble-sized. This surficial armour layer protects the underlying fines from wind entrainment, at least under typical wind conditions; however, particle emissions still do occur under high wind speeds. The dynamics of particle entrainment from within these surfaces are investigated herein. It is shown that the dynamics of the boundary layer flow over these lag surfaces are influenced by the inherent roughness and permeability of the surficial armour layer, such that the flow resembles those observed over and within vegetation canopies, and those associated with permeable gravel-bed river channels. Restriction of air flow within the permeable surface produces a high-pressure zone within the pore spaces, resulting in a Kelvin-Helmholtz shear instability, which triggers coherent motions in the form of repeating burst-sweep cycles. Using Laser Doppler Anemometry (LDA), it is demonstrated that the lower boundary layer is characterized by both Q4 sweeping motions and Q2 bursting motions, while the upper boundary layer is dominated by Q2 bursts. Pore air motions within the slag material were measured using buried pressure ports. It is shown that the mean pressure gradient which forms within the slag material results in net upward displacement of air, or wind pumping. However, this net upward motion is a result of rapid oscillatory motions which are directly driven by coherent boundary layer motions. It is also demonstrated that these coherent motions are able to penetrate at least 4 cm through the surficial armour layer, thereby transporting turbulent kinetic energy (TKE) downward to the dust-laden sub-surface layer. This represents a mechanism of momentum transfer that is able to reach the erodible material, while the wind pumping effect represents a mechanism for particle exhaustion.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Ping; Yan, Pengfei; Romero, Eric

Capacity loss, and voltage decrease upon electrochemical charge-discharge cycling observed in lithium-rich layered cathode oxides (Li[Li xMn yTM 1-x-y]O 2, TM = Ni, Co or Fe) have recently been attributed to the formation of a surface reconstructed layer (SRL) that evolves from a thin (<2 nm), defect spinel layer upon the first charge, to a relatively thick (~5nm), spinel or rock-salt layer upon continuous charge-discharge cycling. Here we report observations of a SRL and structural evolution of the SRL on the Li[Li 0.2Ni 0.2Mn 0.6]O 2 (LNMO) particles, which are identical to those reported due to the charge-discharge cycle butmore » are a result of electron-beam irradiation during scanning transmission electron microscopy (STEM) imaging. Sensitivity of the lithium-rich layered oxides to high-energy electrons leads to the formation of thin, defect spinel layer on surfaces of the particles when exposed to a 200kV electron beam for as little as 30 seconds under normal high-resolution STEM imaging conditions. Further electron irradiation produces a thicker layer of the spinel phase, ultimately producing a rock-salt layer at a higher electron exposure. Atomic-scale chemical mapping by electron dispersive X-ray spectroscopy in STEM indicates the electron-beam-induced SRL formation on LNMO is accomplished by migration of the transition metal ions to the Li sites without breaking down the lattice. The observation through this study provides an insight for understanding the mechanism of forming the SRL and also possibly a mean to study structural evolution in the Li-rich layered oxides without involving the electrochemistry.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Ping; Yan, Pengfei; Romero, Eric

Capacity loss, and voltage fade upon electrochemical charge-discharge cycling observed in lithium-rich layered cathode oxides (Li[LixMnyTM1-x-y]O2 , TM = Ni, Co or Fe) have recently been identified to be correlated to the gradual phase transformation, featuring the formation of a surface reconstructed layer (SRL) that evolves from a thin (<2 nm), defect spinel layer upon the first charge, to a relatively thick (~5 nm), spinel or rock-salt layer upon continuous charge-discharge cycling. Here we report observations of a SRL and structural evolution of the SRL on the Li[Li0.2Ni0.2Mn0.6]O2 (LMR) particles, which are identical to those reported due to the charge-dischargemore » cycle but are a result of electron-beam irradiation during scanning transmission electron microscopy (STEM) imaging. Sensitivity of the lithium-rich layered oxides to high-energy electrons leads to the formation of thin, defect spinel layer on surfaces of the particles when exposed to a 200 kV electron beam for as little as 30 seconds under normal high-resolution STEM imaging conditions. Further electron irradiation produces a thicker layer of the spinel phase, ultimately producing a rock-salt layer at a higher electron exposure. Atomic-scale chemical mapping by energy dispersive X-ray spectroscopy in STEM indicates the electron-beam-induced SRL formation on LMR is accomplished by migration of the transition metal ions to the Li sites without breaking down the lattice. This study provides an insight for understanding the mechanism of forming the SRL and also possibly a mean to study structural evolution in the Li-rich layered oxides without involving the electrochemistry.« less

Automated assessment of the remineralization of artificial enamel lesions with polarization-sensitive optical coherence tomography

PubMed Central

Lee, Robert C.; Kang, Hobin; Darling, Cynthia L.; Fried, Daniel

2014-01-01

Accurate measurement of the highly mineralized transparent surface layer that forms on caries lesions is important for diagnosis of the lesion activity because chemical intervention can slow or reverse the caries process via remineralization. Previous in-vitro and in-vivo studies have demonstrated that polarization-sensitive optical coherence tomography (PS-OCT) can nondestructively image the subsurface lesion structure and the highly mineralized transparent surface zone of caries lesions. The purpose of this study was to develop an approach to automatically process 3-dimensional PS-OCT images and to accurately assess the remineralization process in simulated enamel lesions. Artificial enamel lesions were prepared on twenty bovine enamel blocks using two models to produce varying degree of demineralization and remineralization. The thickness of the transparent surface layer and the integrated reflectivity of the subsurface lesion were measured using PS-OCT. The automated transparent surface layer detection algorithm was able to successfully detect the transparent surface layers with high sensitivity ( = 0.92) and high specificity ( = 0.97). The estimated thickness of the transparent surface layer showed a strong correlation with polarized light microscopy (PLM) measurements of all regions (R2 = 0.90). The integrated reflectivity, ΔR, and the integrated mineral loss, ΔZ, showed a moderate correlation (R2 = 0.32). This study demonstrates that PS-OCT can automatically measure the changes in artificial enamel lesion structure and severity upon exposure to remineralization solutions. PMID:25401009

Firn structure of Larsen C Ice Shelf, Antarctic Peninsula, from in-situ geophysical surveys

NASA Astrophysics Data System (ADS)

Kulessa, B.; Brisbourne, A.; Kuipers Munneke, P.; Bevan, S. L.; Luckman, A. J.; Hubbard, B. P.; Ashmore, D.; Holland, P.; Jansen, D.; King, E. C.; O'Leary, M.; McGrath, D.

2015-12-01

Rising surface temperatures have been causing firn layers on Antarctic Peninsula ice shelves to compact, a process that is strongly implicated in ice shelf disintegration. Firn compaction is expected to warm the ice column and given sufficiently wet and compacted firn layers, to allow meltwater to penetrate into surface crevasses and thus enhance the potential for hydrofracture. On Larsen C Ice Shelf a compacting firn layer has previously been inferred from airborne radar and satellite data, with strongly reduced air contents in Larsen C's north and north-west. The hydrological processes governing firn compaction, and the detailed firn structures they produce, have so far remained uncertain however. Using integrated seismic refraction, MASW (Multi-Channel Analysis of Surface Waves), seismoelectric and ground-penetrating radar (GPR) data, we reveal vertical and horizontal changes in firn structure across Larsen C Ice Shelf. Particular attention is paid to the spatial prevalence of refrozen meltwaters within firn, such as the massive subsurface ice layer discovered recently by the NERC-funded MIDAS project in Cabinet Inlet in Larsen C's extreme northwest. Such ice layers or lenses are particularly dramatic manifestations of increased ice shelf densities and temperatures, and contrast sharply with the relatively uncompacted firn layers present in the ice shelf's southeast. We consider our observations in the context of a one-dimensional firn model for Larsen C Ice Shelf that includes melt percolation and refreezing, and discuss temporal changes in firn layer structures due to surface melt and ponding.

Collective Surfing of Chemically Active Particles

NASA Astrophysics Data System (ADS)

Masoud, Hassan; Shelley, Michael J.

2014-03-01

We study theoretically the collective dynamics of immotile particles bound to a 2D surface atop a 3D fluid layer. These particles are chemically active and produce a chemical concentration field that creates surface-tension gradients along the surface. The resultant Marangoni stresses create flows that carry the particles, possibly concentrating them. For a 3D diffusion-dominated concentration field and Stokesian fluid we show that the surface dynamics of active particle density can be determined using nonlocal 2D surface operators. Remarkably, we also show that for both deep or shallow fluid layers this surface dynamics reduces to the 2D Keller-Segel model for the collective chemotactic aggregation of slime mold colonies. Mathematical analysis has established that the Keller-Segel model can yield finite-time, finite-mass concentration singularities. We show that such singular behavior occurs in our finite-depth system, and study the associated 3D flow structures.

Diagenetic Layers in the Upper Walls of Valles Marineris, Mars: Evidence for Drastic Climate Change Since the Mid-Hesperian

NASA Technical Reports Server (NTRS)

Treiman, Allan H.; Fuks, Kelly H.; Murchie, Scott

1995-01-01

A packet of relatively resistant layers, totaling approx. 400 m thickness, is present at the tops of the chasma walls throughout Valles Marineris. The packet consists of an upper dark layer (approx. 50 m thick), a central bright layer (approx. 250 m thick), and a lower dark layer (approx. 100 m thick). The packet appears continuous and of nearly constant thickness and depth below ground surface over the whole Valles system (4000 km E-W, 800 km N-S), independent of elevation (3-10 km) and age of plateau surface (Noachian through upper Hesperian). The packet continues undisturbed beneath the boundary between surface units of Noachian and Hesperian ages, and continues undisturbed beneath impact craters transected by chasma walls. These attributes are not consistent with layer formation by volcanic or sedimentary deposition, and are consistent with layer formation in situ, i.e., by diagenesis, during or after upper Hesperian time. Diagenesis seems to require the action of aqueous solutions in the near subsurface, which are not now stable in the Valles Marineris area. To permit the stability of aqueous solutions, Mars must have had a fairly dense atmosphere, greater than or equal to 1 bar CO2, when the layers formed. Obliquity variations appear to be incapable of producing such a massive atmosphere so late in Mars' history.

Engineered biomimicry: polymeric replication of surface features found on insects

NASA Astrophysics Data System (ADS)

Pulsifer, Drew P.; Lakhtakia, Akhlesh; Martín-Palma, Raúl J.; Pantano, Carlo G.

2011-04-01

By combining the modified conformal-evaporated-film-by-rotation (M-CEFR) technique with nickel electroforming, we have produced master negatives of nonplanar biotemplates. An approximately 250-nm-thick conformal coating of nanocrystaline nickel is deposited on a surface structure of interest found in class Insecta, and the coating is then reinforced with a roughly 60-μm-thick structural layer of nickel by electroforming. This structural layer endows the M-CEFR coating with the mechanical robustness necessary for casting or stamping multiple polymer replicas of the biotemplate. We have made master negatives of blowfly corneas, beetle elytrons, and butterfly wings.

Tailoring bifunctional hybrid organic–inorganic nanoadsorbents by the choice of functional layer composition probed by adsorption of Cu2+ ions

PubMed Central

Tomina, Veronika V; Melnyk, Inna V; Zub, Yuriy L; Kareiva, Aivaras; Vaclavikova, Miroslava; Kessler, Vadim G

2017-01-01

Spherical silica particles with bifunctional (≡Si(CH2)3NH2/≡SiCH3, ≡Si(CH2)3NH2/≡Si(CH2)2(CF2)5CF3) surface layers were produced by a one-step approach using a modified Stöber method in three-component alkoxysilane systems, resulting in greatly increased contents of functional components. The content of functional groups and thermal stability of the surface layers were analyzed by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, and 13C and 29Si solid-state NMR spectroscopy revealing their composition and organization. The fine chemical structure of the surface in the produced hybrid adsorbent particles and the ligand distribution were further investigated by electron paramagnetic resonance (EPR) and electron spectroscopy of diffuse reflectance (ESDR) spectroscopy using Cu2+ ion coordination as a probe. The composition and structure of the emerging surface complexes were determined and used to provide an insight into the molecular structure of the surfaces. It was demonstrated that the introduction of short hydrophobic (methyl) groups improves the kinetic characteristics of the samples during the sorption of copper(II) ions and promotes fixation of aminopropyl groups on the surface of silica microspheres. The introduction of long hydrophobic (perfluoroctyl) groups changes the nature of the surface, where they are arranged in alternately hydrophobic/hydrophilic patches. This makes the aminopropyl groups huddled and less active in the sorption of metal cations. The size and aggregation/morphology of obtained particles was optimized controlling the synthesis conditions, such as concentrations of reactants, basicity of the medium, and the process temperature. PMID:28243572

The plume head-continental lithosphere interaction using a tectonically realistic formulation for the lithosphere

NASA Astrophysics Data System (ADS)

Burov, E.; Guillou-Frottier, L.

2005-05-01

Current debates on the existence of mantle plumes largely originate from interpretations of supposed signatures of plume-induced surface topography that are compared with predictions of geodynamic models of plume-lithosphere interactions. These models often inaccurately predict surface evolution: in general, they assume a fixed upper surface and consider the lithosphere as a single viscous layer. In nature, the surface evolution is affected by the elastic-brittle-ductile deformation, by a free upper surface and by the layered structure of the lithosphere. We make a step towards reconciling mantle- and tectonic-scale studies by introducing a tectonically realistic continental plate model in large-scale plume-lithosphere interaction. This model includes (i) a natural free surface boundary condition, (ii) an explicit elastic-viscous(ductile)-plastic(brittle) rheology and (iii) a stratified structure of continental lithosphere. The numerical experiments demonstrate a number of important differences from predictions of conventional models. In particular, this relates to plate bending, mechanical decoupling of crustal and mantle layers and tension-compression instabilities, which produce transient topographic signatures such as uplift and subsidence at large (>500 km) and small scale (300-400, 200-300 and 50-100 km). The mantle plumes do not necessarily produce detectable large-scale topographic highs but often generate only alternating small-scale surface features that could otherwise be attributed to regional tectonics. A single large-wavelength deformation, predicted by conventional models, develops only for a very cold and thick lithosphere. Distinct topographic wavelengths or temporarily spaced events observed in the East African rift system, as well as over French Massif Central, can be explained by a single plume impinging at the base of the continental lithosphere, without evoking complex asthenospheric upwelling.

Solar cell collector and method for producing same

NASA Technical Reports Server (NTRS)

Evans, J. C., Jr. (Inventor)

1978-01-01

A transparent, conductive collector layer containing conductive metal channels is formed as a layer on a photovoltaic substrate by coating a photovoltaic substract with a conductive mixed metal layer. A heat sink having portions protruding from one of its surfaces is attached. These protruding portions define a continuous pattern in combination with recessed regions among them such that they are in contact with the conductive layer of the photovoltaic substrate. Heating the substrate while simultaneously oxidizing the portions of the conductive layer exposed to a gaseous oxidizing substance forced into the recessed regions of the heat sink, creates a transparent metal oxide layer on the substrate. A continous pattern of highly conductive metal channels is contained in the metal oxide layer.

Multi-Dimensional Sensors and Sensing Systems

NASA Technical Reports Server (NTRS)

Stetter, Joseph R. (Inventor); Shirke, Amol G. (Inventor)

2014-01-01

A universal microelectromechanical (MEMS) nano-sensor platform having a substrate and conductive layer deposited in a pattern on the surface to make several devices at the same time, a patterned insulation layer, wherein the insulation layer is configured to expose one or more portions of the conductive layer, and one or more functionalization layers deposited on the exposed portions of the conductive layer to make multiple sensing capability on a single MEMS fabricated device. The functionalization layers are adapted to provide one or more transducer sensor classes selected from the group consisting of: radiant, electrochemical, electronic, mechanical, magnetic, and thermal sensors for chemical and physical variables and producing more than one type of sensor for one or more significant parameters that need to be monitored.

Computer program for design of two-dimensional supersonic turbine rotor blades with boundary-layer correction

NASA Technical Reports Server (NTRS)

Goldman, L. J.; Scullin, V. J.

1971-01-01

A FORTRAN 4 computer program for the design of two-dimensional supersonic rotor blade sections corrected for boundary-layer displacement thickness is presented. The ideal rotor is designed by the method of characteristics to produce vortex flow within the blade passage. The boundary-layer parameters are calculated by Cohen and Reshotoko's method for laminar flow and Sasman and Cresci's method for turbulent flow. The program input consists essentially of the blade surface Mach number distribution and total flow conditions. The primary output is the corrected blade profile and the boundary-layer parameters.

A comparison between active and passive sensing of soil moisture from vegetated terrains

NASA Technical Reports Server (NTRS)

Fung, A. K.; Eom, H. J.

1985-01-01

A comparison between active and passive sensing of soil moisture over vegetated areas is studied via scattering models. In active sensing three contributing terms to radar backscattering can be identified: (1) the ground surface scatter term; (2) the volume scatter term representing scattering from the vegetation layer; and (3) the surface volume scatter term accounting for scattering from both surface and volume. In emission three sources of contribution can also be identified: (1) surface emission; (2) upward volume emission from the vegetation layer; and (3) downward volume emission scattered upward by the ground surface. As ground moisture increases, terms (1) and (3) increase due to increase in permittivity in the active case. However, in passive sensing, term (1) decreases but term (3) increases for the same reason. This self compensating effect produces a loss in sensitivity to change in ground moisture. Furthermore, emission from vegetation may be larger than that from the ground. Hence, the presence of vegetation layer causes a much greater loss of sensitivity to passive than active sensing of soil moisture.

A comparison between active and passive sensing of soil moisture from vegetated terrains

NASA Technical Reports Server (NTRS)

Fung, A. K.; Eom, H. J.

1984-01-01

A comparison between active and passive sensing of soil moisture over vegetated areas is studied via scattering models. In active sensing three contributing terms to radar backscattering can be identified: (1) the ground surface scatter term; (2) the volume scatter term representing scattering from the vegetation layer; and (3) the surface volume scatter term accounting for scattering from both surface and volume. In emission three sources of contribution can also be identified: (1) surface emission; (2) upward volume emission from the vegetation layer; and (3) downward volume emission scattered upward by the ground surface. As ground moisture increases, terms (1) and (3) increase due to increase in permittivity in the active case. However, in passive sensing, term (1) decreases but term (3) increases for the same reason. This self conpensating effect produces a loss in sensitivity to change in ground moisture. Furthermore, emission from vegetation may be larger than that from the ground. Hence, the presence of vegetation layer causes a much greater loss of sensitivity to passive than active sensing of soil moisture.

Faster proton transfer dynamics of water on SnO2 compared to TiO2.

PubMed

Kumar, Nitin; Kent, Paul R C; Bandura, Andrei V; Kubicki, James D; Wesolowski, David J; Cole, David R; Sofo, Jorge O

2011-01-28

Proton jump processes in the hydration layer on the iso-structural TiO(2) rutile (110) and SnO(2) cassiterite (110) surfaces were studied with density functional theory molecular dynamics. We find that the proton jump rate is more than three times faster on cassiterite compared with rutile. A local analysis based on the correlation between the stretching band of the O-H vibrations and the strength of H-bonds indicates that the faster proton jump activity on cassiterite is produced by a stronger H-bond formation between the surface and the hydration layer above the surface. The origin of the increased H-bond strength on cassiterite is a combined effect of stronger covalent bonding and stronger electrostatic interactions due to differences of its electronic structure. The bridging oxygens form the strongest H-bonds between the surface and the hydration layer. This higher proton jump rate is likely to affect reactivity and catalytic activity on the surface. A better understanding of its origins will enable methods to control these rates.

The influence of laser alloying on the structure and mechanical properties of AlMg5Si2Mn surface layers

NASA Astrophysics Data System (ADS)

Pakieła, W.; Tański, T.; Brytan, Z.; Labisz, K.

2016-04-01

The goal of this paper was focused on investigation of microstructure and properties of surface layer produced during laser surface treatment of aluminium alloy by high-power fibre laser. The performed laser treatment involves remelting and feeding of Inconel 625 powder into the aluminium surface. As a base metal was used aluminium alloy AlMg5Si2Mn. The Inconel powder was injected into the melt pool and delivered by a vacuum feeder at a constant rate of 4.5 g/min. The size of Inconel alloying powder was in the range 60-130 µm. In order to remelt the aluminium alloy surface, the fibre laser of 3 kW laser beam power has been used. The linear laser scan rate of the beam was set 0.5 m/min. Based on performed investigations, it was possible to obtain the layer consisting of heat-affected zone, transition zone and remelted zone, without cracks and defects having much higher hardness value compared to the non-alloyed material.

Estimating multivariate response surface model with data outliers, case study in enhancing surface layer properties of an aircraft aluminium alloy

NASA Astrophysics Data System (ADS)

Widodo, Edy; Kariyam

2017-03-01

To determine the input variable settings that create the optimal compromise in response variable used Response Surface Methodology (RSM). There are three primary steps in the RSM problem, namely data collection, modelling, and optimization. In this study focused on the establishment of response surface models, using the assumption that the data produced is correct. Usually the response surface model parameters are estimated by OLS. However, this method is highly sensitive to outliers. Outliers can generate substantial residual and often affect the estimator models. Estimator models produced can be biased and could lead to errors in the determination of the optimal point of fact, that the main purpose of RSM is not reached. Meanwhile, in real life, the collected data often contain some response variable and a set of independent variables. Treat each response separately and apply a single response procedures can result in the wrong interpretation. So we need a development model for the multi-response case. Therefore, it takes a multivariate model of the response surface that is resistant to outliers. As an alternative, in this study discussed on M-estimation as a parameter estimator in multivariate response surface models containing outliers. As an illustration presented a case study on the experimental results to the enhancement of the surface layer of aluminium alloy air by shot peening.

Rapid Aluminum Nanoparticle Production by Milling in NH₃ and CH₃NH₂ Atmospheres: An Experimental and Theoretical Study.

PubMed

McMahon, Brandon W; Yu, Jiang; Boatz, Jerry A; Anderson, Scott L

2015-07-29

Ball milling of aluminum in gaseous atmospheres of ammonia and monomethylamine (MMA) was found to produce particles in the 100 nm size range with high efficiency. A combination of mass spectrometry, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis with mass spectrometric product analysis (TGA-MS), scanning electron microscopy (SEM), infrared spectroscopy, and dynamic light scattering (DLS) was used to study the particles and the chemical interactions responsible for particle production. To help understand the nature of the surface chemistry, high level quantum chemical calculations were performed to predict the structures and energetics for binding and reactions of NH3 and MMA on aluminum surfaces. Both NH3 and MMA react with aluminum under milling conditions, producing H2 and other gaseous products, and leaving the surfaces functionalized. The surface functionalization enhances size reduction by reducing the surface free energy and the tendency toward mechanochemical welding. For both NH3 and MMA, the particle cores are metallic aluminum, but the surface chemical properties are quite different. The ammonia-milled particles are capped by an AlNxOyHz layer ∼10 nm thick, which passivates the particles. The MMA-milled particles are capped with a thinner passivating layer, such that they are pyrophoric in air and react with N2 at elevated temperatures.

High-strength braze joints between copper and steel

NASA Technical Reports Server (NTRS)

Kuhn, R. F.

1967-01-01

High-strength braze joints between copper and steel are produced by plating the faying surface of the copper with a layer of gold. This reduces porosity in the braze area and strengthens the resultant joint.

Surface layer modification of ion bombarded HDPE

NASA Astrophysics Data System (ADS)

Bielinski, D.; Lipinski, P.; Slusarski, L.; Grams, J.; Paryjczak, T.; Jagielski, J.; Turos, A.; Madi, N. K.

2004-08-01

Press-moulded, high density polyethylene (HDPE) samples were subjected to ion bombardment and effects of the modification studied. He + ions of energy 100 keV or Ar + ions of energy 130 keV were applied in the range of dose 1-30 × 10 15/cm 2 or 1-100 × 10 14/cm 2, respectively. This paper has been focused on structural changes of the surface layer. The consequences of the modification were studied with TOF-SIMS and FTIR-IRS techniques. The results point on two mechanisms taking place simultaneously: ionization of polymer macromolecules and chain scission--resulting in creation of macroradicals. Both of them produce oxidation and lead to significant release of hydrogen. The former diminishes for the highest ion doses, however, creation of molecular oxygen cannot be excluded. The latter in the case of Ar + ion bombardment is reflected by prevailing degradation of the surface layer of HDPE. Contrary to the effect of heavy ions, He + ion bombardment was found to produce significant increase of the material hardness, which was explained by crosslinking of polyethylene. A mechanism of polyacetylene formation, proceeding finally to cross-polymerization of the polymer was proposed. Apart from structural changes, the modification revealed additionally a possibility to improve the wettability of the polymer.

Nanoparticle layer deposition for highly controlled multilayer formation based on high- coverage monolayers of nanoparticles

PubMed Central

Liu, Yue; Williams, Mackenzie G.; Miller, Timothy J.; Teplyakov, Andrew V.

2015-01-01

This paper establishes a strategy for chemical deposition of functionalized nanoparticles onto solid substrates in a layer-by-layer process based on self-limiting surface chemical reactions leading to complete monolayer formation within the multilayer system without any additional intermediate layers – nanoparticle layer deposition (NPLD). This approach is fundamentally different from previously established traditional layer-by-layer deposition techniques and is conceptually more similar to well-known atomic and molecular – layer deposition processes. The NPLD approach uses efficient chemical functionalization of the solid substrate material and complementary functionalization of nanoparticles to produce a nearly 100% coverage of these nanoparticles with the use of “click chemistry”. Following this initial deposition, a second complete monolayer of nanoparticles is deposited using a copper-catalyzed “click reaction” with the azide-terminated silica nanoparticles of a different size. This layer-by-layer growth is demonstrated to produce stable covalently-bound multilayers of nearly perfect structure over macroscopic solid substrates. The formation of stable covalent bonds is confirmed spectroscopically and the stability of the multilayers produced is tested by sonication in a variety of common solvents. The 1-, 2- and 3-layer structures are interrogated by electron microscopy and atomic force microscopy and the thickness of the multilayers formed is fully consistent with that expected for highly efficient monolayer formation with each cycle of growth. This approach can be extended to include a variety of materials deposited in a predesigned sequence on different substrates with a highly conformal filling. PMID:26726273

Fabrication and characterization of anode catalyst layers with structural variations for DMFC

NASA Astrophysics Data System (ADS)

Wang, Dazhi; Shi, Peng; Zhou, Peng; Mao, Qing; Liang, Junsheng; Wang, Suli; Li, Yang; Ren, Tongqun; Sun, Gongquan

2018-04-01

In this work, the electrohydrodynamic jet (E-Jet) Layer-by-Layer (LbL) deposition technique was employed to produce anode catalyst layer (CL) structure for direct methanol fuel cells (DMFC). The CLs with different thickness and porosity were fabricated with the control of the E-Jet deposition parameters. Then, the deposited anode CLs with structural variations were assembled to membrane electrode assemblies (MEAs). The results showed that the anode CL with higher porosity contributed higher dispersed catalyst, which further induced greater electrochemical active surface area (ESA) and higher performance. At optimized working condition the anode CL with high-dispersed catalyst of was produced using the E-Jet LbL deposition technique. It was observed that the peak power density is 72.8 mW cm‑2 for the cell having a porosity of 0.63, which has an increase of about 33% after modification of the CL structure.

XPS-nanocharacterization of organic layers electrochemically grafted on the surface of SnO2 thin films to produce a new hybrid material coating

NASA Astrophysics Data System (ADS)

Drevet, R.; Dragoé, D.; Barthés-Labrousse, M. G.; Chaussé, A.; Andrieux, M.

2016-10-01

This work presents the synthesis and the characterization of hybrid material thin films obtained by the combination of two processes. The electrochemical grafting of organic layers made of carboxyphenyl moieties is carried out from the reduction of a diazonium salt on tin dioxide (SnO2) thin films previously deposited on Si substrates by metal organic chemical vapor deposition (MOCVD). Since the MOCVD experimental parameters impact the crystal growth of the SnO2 layer (i.e. its morphology and its texturation), various electrochemical grafting models can occur, producing different hybrid materials. In order to evidence the efficiency of the electrochemical grafting of the carboxyphenyl moieties, X-ray Photoelectron Spectroscopy (XPS) is used to characterize the first nanometers in depth of the synthesized hybrid material layer. Then three electrochemical grafting models are proposed.

Venus: Vertical accretion of crust and depleted mantle and implications for geological history and processes

NASA Technical Reports Server (NTRS)

Head, James W.; Parmentier, E. M.; Hess, P. C.

1994-01-01

Models for the vertical accretion of a basaltic crust and depleted mantle layer on Venus over geologic time predict the eventual development of a net negatively buoyant depleted mantle layer, its foundering and its remixing with the underlying mantle. The consequences of the development of this layer, its loss, and the aftermath are investigated and compared to the geologic record of Venus revealed by Magellan. The young average age of the surface of Venus (several hundred million years), the formation of the heavily deformed tessera regions, the subsequent emplacement of widespread volcanic plains, the presently low rate of volcanic activity, and impact crater population that cannot be distinguished from a completely spatially random distribution, and the small number of impact craters embayed by volcanism, are all consistent with the development of a depleted mantle layer, its relatively rapid loss followed by large-scale volcanic flooding, and its subsequent reestablishment. We outline a 'catastrophic' tectonic resurfacing model in which the foundering of the depleted mantle layer several hundred million years ago caused globally extensive tectonic deformation and obliteration of the cratering record, accompanied by upwelling of warm fertile mantle and its pressure-release melting to produce extensive surface volcanism in the following period. Venus presently appears to be characterized by a relatively thick depleted mantle layer and lithosphere reestablished over the last several hundred million years following the previous instability event inferred to have produced the tessera terrain.

Refinements to SSiB with an Emphasis on Snow-Physics: Evaluation and Validation Using GSWP and Valdai Data

NASA Technical Reports Server (NTRS)

Mocko, David M.; Sud, Y. C.

2000-01-01

Refinements to the snow-physics scheme of SSiB (Simplified Simple Biosphere Model) are described and evaluated. The upgrades include a partial redesign of the conceptual architecture to better simulate the diurnal temperature of the snow surface. For a deep snowpack, there are two separate prognostic temperature snow layers - the top layer responds to diurnal fluctuations in the surface forcing, while the deep layer exhibits a slowly varying response. In addition, the use of a very deep soil temperature and a treatment of snow aging with its influence on snow density is parameterized and evaluated. The upgraded snow scheme produces better timing of snow melt in GSWP-style simulations using ISLSCP Initiative I data for 1987-1988 in the Russian Wheat Belt region. To simulate more realistic runoff in regions with high orographic variability, additional improvements are made to SSiB's soil hydrology. These improvements include an orography-based surface runoff scheme as well as interaction with a water table below SSiB's three soil layers. The addition of these parameterizations further help to simulate more realistic runoff and accompanying prognostic soil moisture fields in the GSWP-style simulations. In intercomparisons of the performance of the new snow-physics SSiB with its earlier versions using an 18-year single-site dataset from Valdai Russia, the version of SSiB described in this paper again produces the earliest onset of snow melt. Soil moisture and deep soil temperatures also compare favorably with observations.

Geologic and climatic controls on streamflow generation processes in a complex eogenetic karst basin

NASA Astrophysics Data System (ADS)

Vibhava, F.; Graham, W. D.; Maxwell, R. M.

2012-12-01

Streamflow at any given location and time is representative of surface and subsurface contributions from various sources. The ability to fully identify the factors controlling these contributions is key to successfully understanding the transport of contaminants through the system. In this study we developed a fully integrated 3D surface water-groundwater-land surface model, PARFLOW, to evaluate geologic and climatic controls on streamflow generation processes in a complex eogenetic karst basin in North Central Florida. In addition to traditional model evaluation criterion, such as comparing field observations to model simulated streamflow and groundwater elevations, we quantitatively evaluated the model's predictions of surface-groundwater interactions over space and time using a suite of binary end-member mixing models that were developed using observed specific conductivity differences among surface and groundwater sources throughout the domain. Analysis of model predictions showed that geologic heterogeneity exerts a strong control on both streamflow generation processes and land atmospheric fluxes in this watershed. In the upper basin, where the karst aquifer is overlain by a thick confining layer, approximately 92% of streamflow is "young" event flow, produced by near stream rainfall. Throughout the upper basin the confining layer produces a persistent high surficial water table which results in high evapotranspiration, low groundwater recharge and thus negligible "inter-event" streamflow. In the lower basin, where the karst aquifer is unconfined, deeper water tables result in less evapotranspiration. Thus, over 80% of the streamflow is "old" subsurface flow produced by diffuse infiltration through the epikarst throughout the lower basin, and all surface contributions to streamflow originate in the upper confined basin. Climatic variability provides a secondary control on surface-subsurface and land-atmosphere fluxes, producing significant seasonal and interannual variability in these processes. Spatial and temporal patterns of evapotranspiration, groundwater recharge and streamflow generation processes reveal potential hot spots and hot moments for surface and groundwater contamination in this basin.

Ultra-thin clay layers facilitate seismic slip in carbonate faults.

PubMed

Smeraglia, Luca; Billi, Andrea; Carminati, Eugenio; Cavallo, Andrea; Di Toro, Giulio; Spagnuolo, Elena; Zorzi, Federico

2017-04-06

Many earthquakes propagate up to the Earth's surface producing surface ruptures. Seismic slip propagation is facilitated by along-fault low dynamic frictional resistance, which is controlled by a number of physico-chemical lubrication mechanisms. In particular, rotary shear experiments conducted at seismic slip rates (1 ms -1 ) show that phyllosilicates can facilitate co-seismic slip along faults during earthquakes. This evidence is crucial for hazard assessment along oceanic subduction zones, where pelagic clays participate in seismic slip propagation. Conversely, the reason why, in continental domains, co-seismic slip along faults can propagate up to the Earth's surface is still poorly understood. We document the occurrence of micrometer-thick phyllosilicate-bearing layers along a carbonate-hosted seismogenic extensional fault in the central Apennines, Italy. Using friction experiments, we demonstrate that, at seismic slip rates (1 ms -1 ), similar calcite gouges with pre-existing phyllosilicate-bearing (clay content ≤3 wt.%) micro-layers weaken faster than calcite gouges or mixed calcite-phyllosilicate gouges. We thus propose that, within calcite gouge, ultra-low clay content (≤3 wt.%) localized along micrometer-thick layers can facilitate seismic slip propagation during earthquakes in continental domains, possibly enhancing surface displacement.

Sensitivity of boundary layer variables to PBL schemes over the central Tibetan Plateau

NASA Astrophysics Data System (ADS)

Xu, L.; Liu, H.; Wang, L.; Du, Q.; Liu, Y.

2017-12-01

Planetary Boundary Layer (PBL) parameterization schemes play critical role in numerical weather prediction and research. They describe physical processes associated with the momentum, heat and humidity exchange between land surface and atmosphere. In this study, two non-local (YSU and ACM2) and two local (MYJ and BouLac) planetary boundary layer parameterization schemes in the Weather Research and Forecasting (WRF) model have been tested over the central Tibetan Plateau regarding of their capability to model boundary layer parameters relevant for surface energy exchange. The model performance has been evaluated against measurements from the Third Tibetan Plateau atmospheric scientific experiment (TIPEX-III). Simulated meteorological parameters and turbulence fluxes have been compared with observations through standard statistical measures. Model results show acceptable behavior, but no particular scheme produces best performance for all locations and parameters. All PBL schemes underestimate near surface air temperatures over the Tibetan Plateau. By investigating the surface energy budget components, the results suggest that downward longwave radiation and sensible heat flux are the main factors causing the lower near surface temperature. Because the downward longwave radiation and sensible heat flux are respectively affected by atmosphere moisture and land-atmosphere coupling, improvements in water vapor distribution and land-atmosphere energy exchange is meaningful for better presentation of PBL physical processes over the central Tibetan Plateau.

Applying a uniform layer of disinfectant by wiping.

PubMed

Cooper, D W

2000-01-01

Disinfection or sterilization often requires applying a film of liquid to a surface, frequently done by using a wiper as the applicator. The wiper must not only hold a convenient amount of liquid, it must deposit it readily and uniformly. Contact time is critical to disinfection efficacy. Evaporation can limit the contact time. To lengthen the contact time, thickly applied layers are generally preferred. The thickness of such layers can be determined by using dyes or other tracers, as long as the tracers do not significantly affect the liquid's surface tension and viscosity and thus do not affect the thickness of the applied layer. Alternatively, as done here, the thickness of the layer can be inferred from the weight loss of the wiper. Results are reported of experiments on thickness of the layers applied under various conditions. Near saturation, hydrophilic polyurethane foam wipers gave layers roughly 10 microns thick, somewhat less than expected from hydrodynamic theory, but more than knitted polyester or woven cotton. Wipers with large liquid holding capacity, refilled often, should produce more nearly uniform layers. Higher pressures increase saturation in the wiper, tending to thicken the layer, but higher pressures also force liquid from the interface, tending to thin the layer, so the net result could be thicker or thinner layers, and there is likely to be an optimal pressure.

Surface plasmon-assisted microscope.

PubMed

Borejdo, Julian; Gryczynski, Zygmunt; Fudala, Rafal; Joshi, Chaitanya R; Borgmann, Kathleen; Ghorpade, Anuja; Gryczynski, Ignacy

2018-06-01

Total internal reflection microscopy (TIRF) has been a powerful tool in biological research. The most valuable feature of the method has been the ability to image 100- to 200-nm-thick layer of cell features adjacent to a coverslip, such as membrane lipids, membrane receptors, and structures proximal-to-basal membranes. Here, we demonstrate an alternative method of imaging thin-layer proximal-to-basal membranes by placing a sample on a high refractive index coverslip covered by a thin layer of gold. The sample is illuminated using the Kretschmann method (i.e., from the top to an aqueous medium). Fluorophores that are close to the metal surface induce surface plasmons in the metal film. Fluorescence from fluorophores near the metal surface couple with surface plasmons allowing them to penetrate the metal surface and emerge at a surface plasmon coupled emission angle. The thickness of the detection layer is further reduced in comparison with TIRF by metal quenching of fluorophores at a close proximity (below 10 nm) to a surface. Fluorescence is collected by a high NA objective and imaged by EMCCD or converted to a signal by avalanche photodiode fed by a single-mode optical fiber inserted in the conjugate image plane of the objective. The system avoids complications of through-the-objective TIRF associated with shared excitation and emission light path, has thin collection thickness, produces excellent background rejection, and is an effective method to study molecular motion. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Surface Structure Formation in Direct Chill (DC) Casting of Al Alloys

NASA Astrophysics Data System (ADS)

Bayat, Nazlin; Carlberg, Torbjörn

2014-05-01

The aim of this study is to increase the understanding of the surface zone formation during direct chill (DC) casting of aluminum billets produced by the air slip technology. The depth of the shell zone, with compositions deviating from the bulk, is of large importance for the subsequent extrusion productivity and quality of final products. The surface microstructures of 6060 and 6005 aluminum alloys in three different surface appearances—defect free, wavy surface, and spot defects—were studied. The surface microstructures and outer appearance, segregation depth, and phase formation were investigated for the mentioned cases. The results were discussed and explained based on the exudation of liquid metal through the mushy zone and the fact that the exudated liquid is contained within a surface oxide skin. Outward solidification in the surface layer was quantitatively analyzed, and the oxide skin movements explained meniscus line formation. Phases forming at different positions in the segregation zone were analyzed and coupled to a cellular solidification in the exudated layer.

Spectral force analysis using atomic force microscopy reveals the importance of surface heterogeneity in bacterial and colloid adhesion to engineered surfaces.

PubMed

Ma, Huilian; Winslow, Charles J; Logan, Bruce E

2008-04-01

Coatings developed to reduce biofouling of engineered surfaces do not always perform as expected based on their native properties. One reason is that a relatively small number of highly adhesive sites, or the heterogeneity of the coated surface, may control the overall response of the system to initial bacterial deposition. It is shown here using an approach we call spectral force analysis (SFA), based on force volume imaging of the surface with atomic force microscopy, that the behavior of surfaces and coatings can be better understood relative to bacterial adhesion. The application of vapor deposited TiO(2) metal oxide increased bacterial and colloid adhesion, but coating the surface with silica oxide reduced adhesion in a manner consistent with SFA based on analysis of the "stickiest" sites. Application of a TiO(2)-based paint to a surface produced a relatively non-fouling surface. Addition of a hydrophilic layer coating to this surface should have decreased fouling. However, it was observed that this coating actually increased fouling. Using SFA it was shown that the reason for the increased adhesion of bacteria and particles to the hydrophilic layer was that the surface produced by this coating was highly heterogeneous, resulting in a small number of sites that created a stickier surface. These results show that while it is important to manufacture surfaces with coatings that are relatively non-adhesive to bacteria, it is also essential that these coatings have a highly uniform surface chemistry.

Planar waveguide sensor of ammonia

NASA Astrophysics Data System (ADS)

Rogoziński, Roman; Tyszkiewicz, Cuma; Karasiński, Paweł; Izydorczyk, Weronika

2015-12-01

The paper presents the concept of forming ammonia sensor based on a planar waveguide structure. It is an amplitude sensor produced on the basis of the multimode waveguide. The technological base for this kind of structure is the ion exchange method and the sol-gel method. The planar multimode waveguide of channel type is produced in glass substrate (soda-lime glass of Menzel-Glaser company) by the selective Ag+↔Na+ ion exchange. On the surface of the glass substrate a porous (~40%) silica layer is produced by the sol-gel method. This layer is sensitized to the presence of ammonia in the surrounding atmosphere by impregnation with Bromocresol Purple (BCP) dye. Therefore it constitutes a sensor layer. Spectrophotometric tests carried out showed about 50% reduction of cross-transmission changes of such sensor layer for a wave λ=593 nm caused by the presence of 25% ammonia water vapor in its ambience. The radiation source used in this type of sensor structure is a light emitting diode LED. The gradient channel waveguide is designed for frontal connection (optical glue) with a standard multimode telecommunications waveguide 62.5/125μm.

Optical coating design for the annular mirrors of the Alpha I HF laser

NASA Astrophysics Data System (ADS)

Shellan, Jeffrey B.

The dielectric-coating design for the annular mirrors of the Alpha I HF laser is described along with the numerous other designs that were considered. The coatings were required to produce a 0-deg phase shift after one round trip, which involved reflections from six surfaces. Although novel high-reflectivity multilayer dielectric coatings satisfied this requirement, single-layer phase control coatings were preferred because the use of these greatly reduced coating layer-thickness control and thus resulted in significant program savings. Among the single-layer designs investigated, a coating consisting of a 0.06-micron-thick SiO layer was found to be sufficient for all surfaces except those of the rear cone, for which a 0.515-micron thick SiO layer was recommended. The metallic substrate selected was Au. These coatings were found to have a high damage threshold, provide the necessary polarization phase control, and to be quite forgiving to thickness deposition errors that were anticipated using existing chambers.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ling, Yang; Li, Weizhen; Wang, Baoyu

Carbon nanotubes (CNTs) functionalized by a nanothin poly(dopamine) (PDA) layer were produced by a one-pot, nondestructive approach, with direct polymerization of dopamine on the CNT surface. The thickness of the PDA layer can be well-controlled by the reaction time and the proportion of dopamine, and this thickness is found to be the key factor in controlling the dispersion of CNTs and the extent of the interfacial interactions between the CNT@PDA and epoxy resin. SEM results indicated that the dispersion of CNTs in epoxy was improved significantly by coating a nanothin PDA layer onto the CNT surface. In agreeme nt withmore » this finding, the CNTs functionalized with the thinnest PDA layer provided the best mechanical and thermal properties. This result confirmed that a thinner PDA layer could provide optimized interfacial interactions between the CNT@PDA and epoxy matrix and weaken the self-agglomeration of CNTs, which led to an improved effective stress and heat transfer between the CNTs and the polymer matrix.« less

Precipitation of Secondary Phases from the Dissolution of Silicate Glasses

NASA Technical Reports Server (NTRS)

Ming, Douglas W.; Golden, D. C.

2004-01-01

Basaltic and anorthositic glasses were subjected to aqueous weathering conditions in the laboratory where the variables were pH, temperature, glass composition, solution composition, and time. Leached layers formed at the surfaces of glasses followed by the precipitation of X-ray amorphous iron and titanium oxides in acidic and neutral solutions at 25 C over time. Glass under oxidative hydrothermal treatments at 150 C yielded a three-layered surface; which included an outer smectite layer, a Fe-Ti oxide layer and an innermost thin leached layer. The introduction of Mg into solutions facilitated the formation of phyllosilicates. Aqueous hydrothermal treatment of anorthositic glasses (high Ca, low Ti) at 200 C readily formed smectite, whereas, the basaltic glasses (high Ti) were more resistant to alteration and smectite was not observed. Alkaline hydrothermal treatment at 2000e produced zeolites and smectites; only smectites formed at 200 C in neutral solutions. These mineralogical changes, although observed under controlled conditions, have direct applications in interpreting planetary (e.g., meteorite parent bodies) and terrestrial aqueous alteration processes.

Production and Precipitation Hardening of Beta-Type Ti-35Nb-10Cu Alloy Foam for Implant Applications

NASA Astrophysics Data System (ADS)

Mutlu, Ilven; Yeniyol, Sinem; Oktay, Enver

2016-04-01

In this study, beta-type Ti-35Nb-10Cu alloy foams were produced by powder metallurgy method for dental implant applications. 35% Nb was added to stabilize the beta-Ti phase with low Young's modulus. Cu addition enhanced sinterability and gave precipitation hardening capacity to the alloy. Sintered specimens were precipitation hardened in order to enhance the mechanical properties. Electrochemical corrosion behavior of the specimens was examined by electrochemical impedance spectroscopy in artificial saliva. Electrochemical impedance spectroscopy results indicated that the oxide film on the surface of foam is a bi-layer structure consisting of outer porous layer and inner barrier layer. Impedance values of barrier layer were higher than porous layer. Corrosion resistance of specimens decreased at high fluoride concentrations and at low pH of artificial saliva. Corrosion resistance of alloys was slightly decreased with aging. Mechanical properties, microstructure, and surface roughness of the specimens were also examined.

Floating basaltic lava balloons - constrains on the eruptive process based on morphologic parameters

NASA Astrophysics Data System (ADS)

Pacheco, J. M.; Zanon, V.; Kueppers, U.

2011-12-01

The 1998-2001 submarine Serreta eruption brought to science a new challenge. This eruption took place offshore of Terceira Island (Azores), on the so-called Serreta Submarine Ridge, corresponding to a basaltic fissure zone with alkaline volcanism, within a tectonic setting controlled by an hyper-slow spreading rift (the Terceira Rift). The inferred eruptive centers are alignment along a NE-SW direction over an area with depths ranging from 300 to more than 1000 meters. The most remarkable products of this eruption, were large basaltic balloons observed floating at the sea surface. Those balloons, designated as Lava Balloons, are spherical to ellipsoidal structures, ranging from 0.4 up to about 3 m in length, consisting of a thin lava shell enveloping a closed hollow interior, normally formed by a single large vesicle, or a few large convoluted vesicles, that grants an overall density below water density. The cross section of the lava shell usually ranges between 3 and 8 cm and has a distinct layered structure, with different layers defined by different vesicularity, bubble number density and crystal content. The outermost layer is characterized by very small vesicles and high bubble number density whereas the innermost layer has larger vesicles, lower bubble number density and higher crystal content. These observations indicate that the rapidly quenched outer layer preserved the original small vesicles present on the magma at the time of the balloon's formation while the inner layer continued to evolve, producing higher crystal content and allowing time for the expansion of vesicles inward and their efficient coalescence. The outer surface of the balloons exhibits patches of very smooth glassy surface and areas with striation and grooves resulting from small scale fluidal deformation. These surface textures are interpreted as the result of the extrusion process and were produced in a similar manner to the striation found on subaerial toothpaste lavas. Such characteristics are indicative that the outer surface of the balloon quenched as it was being extruded and preserved the scars of a squeeze-up process. On this outer surface, several superficial expansion cracks reveal that after its generation the balloon endured some expansion before reaching the sea surface, most likely due to hydrostatic decompression during its rise. The entire shell of the balloons shows bends and folds resulting from large ductile deformations, also suggesting an origin as an effusive process of squeezing-up a large vesicle through a fissure in a thin lava crust, similarly to the extrusion of a gas filled lava toe. Actually, the volume of the lava shell is not enough to produce all the gas in the balloons interior. More likely, at an earlier stage, degassing of magma as an open system allowed gas to segregate and accumulate to form large vesicles. The development of very large vesicles would be favored by a ponding system such as a lava lake.

Micro-arc oxidation as a tool to develop multifunctional calcium-rich surfaces for dental implant applications.

PubMed

Ribeiro, A R; Oliveira, F; Boldrini, L C; Leite, P E; Falagan-Lotsch, P; Linhares, A B R; Zambuzzi, W F; Fragneaud, B; Campos, A P C; Gouvêa, C P; Archanjo, B S; Achete, C A; Marcantonio, E; Rocha, L A; Granjeiro, J M

2015-09-01

Titanium (Ti) is commonly used in dental implant applications. Surface modification strategies are being followed in last years in order to build Ti oxide-based surfaces that can fulfill, simultaneously, the following requirements: induced cell attachment and adhesion, while providing a superior corrosion and tribocorrosion performance. In this work micro-arc oxidation (MAO) was used as a tool for the growth of a nanostructured bioactive titanium oxide layer aimed to enhance cell attachment and adhesion for dental implant applications. Characterization of the surfaces was performed, in terms of morphology, topography, chemical composition and crystalline structure. Primary human osteoblast adhesion on the developed surfaces was investigated in detail by electronic and atomic force microscopy as well as immunocytochemistry. Also an investigation on the early cytokine production was performed. Results show that a relatively thick hybrid and graded oxide layer was produced on the Ti surface, being constituted by a mixture of anatase, rutile and amorphous phases where calcium (Ca) and phosphorous (P) were incorporated. An outermost nanometric-thick amorphous oxide layer rich in Ca was present in the film. This amorphous layer, rich in Ca, improved fibroblast viability and metabolic activity as well as osteoblast adhesion. High-resolution techniques allowed to understand that osteoblasts adhered less in the crystalline-rich regions while they preferentially adhere and spread over in the Ca-rich amorphous oxide layer. Also, these surfaces induce higher amounts of IFN-γ cytokine secretion, which is known to regulate inflammatory responses, bone microarchitecture as well as cytoskeleton reorganization and cellular spreading. These surfaces are promising in the context of dental implants, since they might lead to faster osseointegration. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of the Barrier Layer on the Upper Ocean Response to MJO Forcing

NASA Astrophysics Data System (ADS)

Bulusu, S.

2014-12-01

Recently, attention has been given to an upper ocean feature known as the Barrier Layer, which has been shown to impact meteorological phenomena from ENSO to tropical cyclones by suppressing vertical mixing, which reduces sea surface cooling and enhances surface heat fluxes. The calculation defines the Barrier Layer as the difference between the Isothermal Layer Depth (ILD) and Mixed Layer Depth (MLD). Proper representation of these features relies on precise observations of SSS to attain accurate measurements of the MLD and subsequently, the BLT. Compared to the many available in situ SSS measurements, the NASA Aquarius salinity mission currently obtains the closest observations to the true SSS. The role of subsurface features will be better understood through increased accuracy of SSS measurements. In this study BLT estimates are derived from satellite measurements using a multilinear regression model (MRM) in the Indian Ocean. The MRM relates BLT to satellite derived SSS, sea surface temperature (SST) and sea surface height anomalies (SSHA). Besides being a variable that responds passively to atmospheric conditions, SSS significantly controls upper ocean density and therefore the MLD. The formation of a Barrier Layer can lead to possible feedbacks that impact the atmospheric component of the Madden-Julian Oscillation (MJO), as stated as one of the three major hypotheses of the DYNAMO field campaign. This layer produces a stable stratification, reducing vertical mixing, which influences surface heat fluxes and thus could possibly impact atmospheric conditions during the MJO. Establishing the magnitude and extent of SSS variations during the MJO will be a useful tool for data assimilation into models to correctly represent both oceanic thermodynamic characteristics and atmospheric processes during intraseasonal variations.

Layer-by-layer assembly of type I collagen and chondroitin sulfate on aminolyzed PU for potential cartilage tissue engineering application

NASA Astrophysics Data System (ADS)

He, Xianyun; Wang, Yingjun; Wu, Gang

2012-10-01

In this paper, a two-step method was used to synthesize a biodegradable polyurethane (PU) composed of L-lysine ethyl ester diisocyanate (LDI), poly(ɛ-caprolactone) diols (PCL-diol) and 1,4:3,6-dianhydro-D-sorbitol (isosorbide). Amino groups were introduced onto the surface of the PU membrane by an amination reacting with 1,3-propanediamine to produce polycationic substratum. And then, type I collagen (Col) and chondroitin sulfate (CS) were deposited alternately on the polycationic substratum through layer-by-layer (LBL) assembly technology. The FTIR and 1H NMR results showed that the polyurethane was successfully synthesized. Rhodamine B isothiocyanate (RBITC) fluorescence spectrum indicated that amino groups were successfully introduced onto the PU surface. The results of quartz-crystal microbalance (QCM) and RBITC-Col fluorescence spectroscopy monitoring the LBL assemble process presented that the Col/CS deposited alternately on the PU surface. X-ray photoelectron spectroscopy (XPS) results displayed that the CS deposited on the PU surface as well. The surface of the assembled PU became even smoother observed from the surface morphology by atomic force microscopy (AFM) imaging. The hydrophilicity of the PU membrane was greatly enhanced though the modification of LBL assembly. The PU modified with the adsorption of Col/CS may be a potential application for cartilage tissue engineering due to its created mimicking chondrogenic environment.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ivanov, Yuri, E-mail: yufi55@mail.ru; National Research Tomsk State University, 36 Lenina Str., Tomsk, 634050; National Research Tomsk Polytechnic University, 30 Lenina Str., Tomsk, 634050

The present work is devoted to numerical simulation of temperature fields and the analysis of structural and strength properties of the samples surface layer of boron carbide ceramics treated by the high-current pulsed electron-beam of the submillisecond duration. The samples made of sintered boron carbide ceramics are used in these investigations. The problem of calculating the temperature field is reduced to solving the thermal conductivity equation. The electron beam density ranges between 8…30 J/cm{sup 2}, while the pulse durations are 100…200 μs in numerical modelling. The results of modelling the temperature field allowed ascertaining the threshold parameters of the electronmore » beam, such as energy density and pulse duration. The electron beam irradiation is accompanied by the structural modification of the surface layer of boron carbide ceramics either in the single-phase (liquid or solid) or two-phase (solid-liquid) states. The sample surface of boron carbide ceramics is treated under the two-phase state (solid-liquid) conditions of the structural modification. The surface layer is modified by the high-current pulsed electron-beam produced by SOLO installation at the Institute of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk, Russia. The elemental composition and the defect structure of the modified surface layer are analyzed by the optical instrument, scanning electron and transmission electron microscopes. Mechanical properties of the modified layer are determined measuring its hardness and crack resistance. Research results show that the melting and subsequent rapid solidification of the surface layer lead to such phenomena as fragmentation due to a crack network, grain size reduction, formation of the sub-grained structure due to mechanical twinning, and increase of hardness and crack resistance.« less

The structure and properties of boron carbide ceramics modified by high-current pulsed electron-beam

NASA Astrophysics Data System (ADS)

Ivanov, Yuri; Tolkachev, Oleg; Petyukevich, Maria; Teresov, Anton; Ivanova, Olga; Ikonnikova, Irina; Polisadova, Valentina

2016-01-01

The present work is devoted to numerical simulation of temperature fields and the analysis of structural and strength properties of the samples surface layer of boron carbide ceramics treated by the high-current pulsed electron-beam of the submillisecond duration. The samples made of sintered boron carbide ceramics are used in these investigations. The problem of calculating the temperature field is reduced to solving the thermal conductivity equation. The electron beam density ranges between 8…30 J/cm2, while the pulse durations are 100…200 μs in numerical modelling. The results of modelling the temperature field allowed ascertaining the threshold parameters of the electron beam, such as energy density and pulse duration. The electron beam irradiation is accompanied by the structural modification of the surface layer of boron carbide ceramics either in the single-phase (liquid or solid) or two-phase (solid-liquid) states. The sample surface of boron carbide ceramics is treated under the two-phase state (solid-liquid) conditions of the structural modification. The surface layer is modified by the high-current pulsed electron-beam produced by SOLO installation at the Institute of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk, Russia. The elemental composition and the defect structure of the modified surface layer are analyzed by the optical instrument, scanning electron and transmission electron microscopes. Mechanical properties of the modified layer are determined measuring its hardness and crack resistance. Research results show that the melting and subsequent rapid solidification of the surface layer lead to such phenomena as fragmentation due to a crack network, grain size reduction, formation of the sub-grained structure due to mechanical twinning, and increase of hardness and crack resistance.

Dynamic superconcentration at critical-point double-layer gates of conducting nanoporous granules due to asymmetric tangential fluxes

PubMed Central

Wang, Shau-Chun; Wei, Hsien-Hung; Chen, Hsiao-Ping; Tsai, Min-Hsuan; Yu, Chun-Ching; Chang, Hsueh-Chia

2008-01-01

A transient 106-fold concentration of double-layer counterions by a high-intensity electric field is demonstrated at the exit pole of a millimeter-sized conducting nanoporous granule that permits ion permeation. The phenomenon is attributed to a unique counterion screening dynamics that transforms half of the surface field into a converging one toward the ejecting pole. The resulting surface conduction flux then funnels a large upstream electro-osmotic convective counterion flux into the injecting hemisphere toward the zero-dimensional gate of the ejecting hemisphere to produce the superconcentration. As the concentrated counterion is ejected into the electroneutral bulk electrolyte, it attracts co-ions and produce a corresponding concentration of the co-ions. This mechanism is also shown to trap and concentrate co-ion microcolloids of micron sizes too (macroions) and hence has potential application in bead-based molecular assays. PMID:19693364

METHOD FOR COATING GRAPHITE WITH METALLIC CARBIDES

DOEpatents

Steinberg, M.A.

1960-03-22

A method for producing refractory coatings of metallic carbides on graphite was developed. In particular, the graphite piece to be coated is immersed in a molten solution of 4 to 5% by weight of zirconium, titanium, or niobium dissolved in tin. The solution is heated in an argon atmosphere to above 1400 deg C, whereby the refractory metal reacts with the surface of the graphite to form a layer of metalic carbide. The molten solution is cooled to 300 to 400 deg C, and the graphite piece is removed. Excess tin is wiped from the graphite, which is then heated in vacuum to above 2300 deg C. The tin vaporizes from the graphite surface, leaving the surface coated with a tenacious layer of refractory metallic carbide.

Preparation of TiO(2) layers on cp-Ti and Ti6Al4V by thermal and anodic oxidation and by sol-gel coating techniques and their characterization.

PubMed

Velten, D; Biehl, V; Aubertin, F; Valeske, B; Possart, W; Breme, J

2002-01-01

The excellent biocompatibility of titanium and its alloys used, for example, for medical devices, is associated with the properties of their surface oxide. For a better understanding of the tissue reaction in contact with the oxide layer, knowledge of the chemical and physical properties of this layer is of increasing interest. In this study, titania films were produced on cp-Ti and Ti6Al4V substrates by thermal oxidation, anodic oxidation, and by the sol-gel process. The thickness and structure of the films produced under different conditions were determined by ellipsometry, infrared spectroscopy, and X-ray diffraction measurements. The corrosion properties of these layers were investigated by current density-potential curves under physiological conditions. The oxide layers produced on cp-Ti and Ti6Al4V by thermal oxidation consist of TiO(2) in the rutile structure. For the anodized samples the structure of TiO(2) is a mixture of amorphous phase and anatase. The structure of the coatings produced by the sol-gel process for a constant annealing time depends on the annealing temperature, and with increasing temperature successively amorphous, anatase, and rutile structure is observed. Compared to the uncoated, polished substrate with a natural oxide layer, the corrosion resistance of cp-Ti and Ti6Al4V is increased for the samples with an oxide layer thickness of about 100 nm, independent of the oxidation procedure. Copyright 2001 John Wiley & Sons, Inc.

Dry texturing of solar cells

DOEpatents

Sopori, B.L.

1994-10-25

A textured backside of a semiconductor device for increasing light scattering and absorption in a semiconductor substrate is accomplished by applying infrared radiation to the front side of a semiconductor substrate that has a metal layer deposited on its backside in a time-energy profile that first produces pits in the backside surface and then produces a thin, highly reflective, low resistivity, epitaxial alloy layer over the entire area of the interface between the semiconductor substrate and a metal contact layer. The time-energy profile includes ramping up to a first energy level and holding for a period of time to create the desired pit size and density and then rapidly increasing the energy to a second level in which the entire interface area is melted and alloyed quickly. After holding the second energy level for a sufficient time to develop the thin alloy layer over the entire interface area, the energy is ramped down to allow epitaxial crystal growth in the alloy layer. The result is a textured backside on an optically reflective, low resistivity alloy interface between the semiconductor substrate and the metal electrical contact layer. 9 figs.

Dry texturing of solar cells

DOEpatents

Sopori, Bhushan L.

1994-01-01

A textured backside of a semiconductor device for increasing light scattering and absorption in a semiconductor substrate is accomplished by applying infrared radiation to the front side of a semiconductor substrate that has a metal layer deposited on its backside in a time-energy profile that first produces pits in the backside surface and then produces a thin, highly reflective, low resistivity, epitaxial alloy layer over the entire area of the interface between the semiconductor substrate and a metal contact layer. The time-energy profile includes ramping up to a first energy level and holding for a period of time to create the desired pit size and density and then rapidly increasing the energy to a second level in which the entire interface area is melted and alloyed quickly. After holding the second energy level for a sufficient time to develop the thin alloy layer over the entire interface area, the energy is ramped down to allow epitaxial crystal growth in the alloy layer. The result is a textured backside an optically reflective, low resistivity alloy interface between the semiconductor substrate and the metal electrical contact layer.

Improvements of anti-corrosion and mechanical properties of NiTi orthopedic materials by acetylene, nitrogen and oxygen plasma immersion ion implantation

NASA Astrophysics Data System (ADS)

Poon, Ray W. Y.; Ho, Joan P. Y.; Liu, Xuanyong; Chung, C. Y.; Chu, Paul K.; Yeung, Kelvin W. K.; Lu, William W.; Cheung, Kenneth M. C.

2005-08-01

Nickel-titanium shape memory alloys (NiTi) are useful materials in orthopedics and orthodontics due to their unique super-elasticity and shape memory effects. However, the problem associated with the release of harmful Ni ions to human tissues and fluids has been raising safety concern. Hence, it is necessary to produce a surface barrier to impede the out-diffusion of Ni ions from the materials. We have conducted acetylene, nitrogen and oxygen plasma immersion ion implantation (PIII) into NiTi alloys in an attempt to improve the surface properties. All the implanted and annealed samples surfaces exhibit outstanding corrosion and Ni out-diffusion resistance. Besides, the implanted layers are mechanically stronger than the substrate underneath. XPS analyses disclose that the layer formed by C2H2 PIII is composed of mainly TiCx with increasing Ti to C concentration ratios towards the bulk. The nitrogen PIII layer is observed to be TiN, whereas the oxygen PIII layer is composed of oxides of Ti4+, Ti3+ and Ti2+.

Generation of alkali-free and high-proton concentration layer in a soda lime glass using non-contact corona discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ikeda, Hiroshi; Sakai, Daisuke; Nishii, Junji

2013-08-14

Formation mechanisms of alkali-free and high-proton concentration surfaces were investigated for a soda lime glass using a corona discharge treatment under an atmospheric pressure. Protons produced by high DC voltage around an anode needle electrode were incorporated into a sodium ion site in the anode side glass. The sodium ion was swept away to the cathode side as a charge carrier. Then it was discharged. The precipitated sodium was transformed to a Na{sub 2}CO{sub 3} powder when the surface contacted with air. The sodium ion in the glass surface layer of the anode side was replaced completely by protons. Themore » concentration of OH groups in the layer was balanced with the amount of excluded sodium ions. The substitution reaction of sodium ions with protons tends to be saturated according to a square root function of time. The alkali depletion layer formation rate was affected by the large difference in mobility between sodium ions and protons in the glass.« less

Biomimetic coatings enhance tribocorrosion behavior and cell responses of commercially pure titanium surfaces

PubMed Central

Marques, Isabella da Silva Vieira; Alfaro, Maria Fernanda; Saito, Miki Taketomi; da Cruz, Nilson Cristino; Takoudis, Christos; Landers, Richard; Mesquita, Marcelo Ferraz; Nociti Junior, Francisco Humberto; Mathew, Mathew T.; Sukotjo, Cortino; Barão, Valentim Adelino Ricardo

2016-01-01

Biofunctionalized surfaces for implants are currently receiving much attention in the health care sector. Our aims were (1) to create bioactive Ti-coatings doped with Ca, P, Si, and Ag produced by microarc oxidation (MAO) to improve the surface properties of biomedical implants, (2) to investigate the TiO2 layer stability under wear and corrosion, and (3) to evaluate human mesenchymal stem cells (hMSCs) responses cultured on the modified surfaces. Tribocorrosion and cell experiments were performed following the MAO treatment. Samples were divided as a function of different Ca/P concentrations and treatment duration. Higher Ca concentration produced larger porous and harder coatings compared to the untreated group (p < 0.001), due to the presence of rutile structure. Free potentials experiments showed lower drops (−0.6 V) and higher coating lifetime during sliding for higher Ca concentration, whereas lower concentrations presented similar drops (−0.8 V) compared to an untreated group wherein the drop occurred immediately after the sliding started. MAO-treated surfaces improved the matrix formation and osteogenic gene expression levels of hMSCs. Higher Ca/P ratios and the addition of Ag nanoparticles into the oxide layer presented better surface properties, tribocorrosive behavior, and cell responses. MAO is a promising technique to enhance the biological, chemical, and mechanical properties of dental implant surfaces. PMID:27514370

Biomimetic coatings enhance tribocorrosion behavior and cell responses of commercially pure titanium surfaces.

PubMed

Marques, Isabella da Silva Vieira; Alfaro, Maria Fernanda; Saito, Miki Taketomi; da Cruz, Nilson Cristino; Takoudis, Christos; Landers, Richard; Mesquita, Marcelo Ferraz; Nociti Junior, Francisco Humberto; Mathew, Mathew T; Sukotjo, Cortino; Barão, Valentim Adelino Ricardo

2016-09-11

Biofunctionalized surfaces for implants are currently receiving much attention in the health care sector. Our aims were (1) to create bioactive Ti-coatings doped with Ca, P, Si, and Ag produced by microarc oxidation (MAO) to improve the surface properties of biomedical implants, (2) to investigate the TiO2 layer stability under wear and corrosion, and (3) to evaluate human mesenchymal stem cells (hMSCs) responses cultured on the modified surfaces. Tribocorrosion and cell experiments were performed following the MAO treatment. Samples were divided as a function of different Ca/P concentrations and treatment duration. Higher Ca concentration produced larger porous and harder coatings compared to the untreated group (p < 0.001), due to the presence of rutile structure. Free potentials experiments showed lower drops (-0.6 V) and higher coating lifetime during sliding for higher Ca concentration, whereas lower concentrations presented similar drops (-0.8 V) compared to an untreated group wherein the drop occurred immediately after the sliding started. MAO-treated surfaces improved the matrix formation and osteogenic gene expression levels of hMSCs. Higher Ca/P ratios and the addition of Ag nanoparticles into the oxide layer presented better surface properties, tribocorrosive behavior, and cell responses. MAO is a promising technique to enhance the biological, chemical, and mechanical properties of dental implant surfaces.

Preparation of silica stabilized biological templates for the production of metal and layered nanoparticles

DOEpatents

Culver, James N; Royston, Elizabeth; Brown, Adam; Harris, Michael

2013-02-26

The present invention relates to a system and method providing for increased silica growth on a bio-template, wherein the bio-template is pretreated with aniline to produce a uniform silica attractive surface and yielding a significant silica layers of at least 10 nm, and more preferably at least 20 nm in thickness, thereby providing for a high degree of stability to the bio-template.

Production of dissolvable microneedles using an atomised spray process: effect of microneedle composition on skin penetration.

PubMed

McGrath, Marie G; Vucen, Sonja; Vrdoljak, Anto; Kelly, Adam; O'Mahony, Conor; Crean, Abina M; Moore, Anne

2014-02-01

Dissolvable microneedles offer an attractive delivery system for transdermal drug and vaccine delivery. They are most commonly formed by filling a microneedle mold with liquid formulation using vacuum or centrifugation to overcome the constraints of surface tension and solution viscosity. Here, we demonstrate a novel microneedle fabrication method employing an atomised spray technique that minimises the effects of the liquid surface tension and viscosity when filling molds. This spray method was successfully used to fabricate dissolvable microneedles (DMN) from a wide range of sugars (trehalose, fructose and raffinose) and polymeric materials (polyvinyl alcohol, polyvinylpyrrolidone, carboxymethylcellulose, hydroxypropylmethylcellulose and sodium alginate). Fabrication by spraying produced microneedles with amorphous content using single sugar compositions. These microneedles displayed sharp tips and had complete fidelity to the master silicon template. Using a method to quantify the consistency of DMN penetration into different skin layers, we demonstrate that the material of construction significantly influenced the extent of skin penetration. We demonstrate that this spraying method can be adapted to produce novel laminate-layered as well as horizontally-layered DMN arrays. To our knowledge, this is the first report documenting the use of an atomising spray, at ambient, mild processing conditions, to create dissolvable microneedle arrays that can possess novel, laminate layering. Copyright © 2013 Elsevier B.V. All rights reserved.

Selective formation of porous silicon

NASA Technical Reports Server (NTRS)

Fathauer, Jones (Inventor)

1993-01-01

A pattern of porous silicon is produced in the surface of a silicon substrate by forming a pattern of crystal defects in said surface, preferably by applying an ion milling beam through openings in a photoresist layer to the surface, and then exposing said surface to a stain etchant, such as HF:HNO3:H20. The defected crystal will preferentially etch to form a pattern of porous silicon. When the amorphous content of the porous silicon exceeds 70 percent, the porous silicon pattern emits visible light at room temperature.

Morphology and electronic properties of silicon carbide surfaces

NASA Astrophysics Data System (ADS)

Nie, Shu

2007-12-01

Several issues related to SiC surfaces are studied in the thesis using scanning tunneling microscopy/spectroscopy (STM/S) and atomic force microscopy (AFM). Specific surfaces examined include electropolished SiC, epitaxial graphene on SiC, and vicinal (i.e. slightly miscut from a low-index direction) SiC that have been subjected to high temperature hydrogen-etching. The electropolished surfaces are meant to mimic electrochemically etched SiC, which forms a porous network. The chemical treatment of the surface is similar between electropolishing and electrochemical etching, but the etching conditions are slightly different such that the former produces a flat surface (that is amenable to STM study) whereas the latter produces a complex 3-dimensional porous network. We have used these porous SiC layers as semi-permeable membranes in a biosensor, and we find that the material is quite biocompatible. The purpose of the STM/STS study is to investigate the surface properties of the SiC on the atomic scale in an effort to explain this biocompatibility. The observed tunneling spectra are found to be very asymmetric, with a usual amount of current at positive voltages but no observable current at negative voltages. We propose that this behavior is due to surface charge accumulating on an incompletely passivated surface. Measurements on SiC surfaces prepared by various amounts of hydrogen-etching are used to support this interpretation. Comparison with tunneling computations reveals a density of about 10 13 cm-2 fixed charges on both the electro-polished and the H-etched surfaces. The relatively insulating nature observed on the electro-polished SiC surface may provide an explanation for the biocompatibility of the surface. Graphene, a monolayer of carbon, is a new material for electronic devices. Epitaxial graphene on SiC is fabricated by the Si sublimation method in which a substrate is heated up to about 1350°C in ultra-high vacuum (UHV). The formation of the graphene is monitored using low-energy electron diffraction (LEED) and Auger electron spectroscopy, and the morphology of the graphitized surface is studied using AFM and STM. Use of H-etched SiC substrates enables a relatively flat surface morphology, although residual steps remain due to unintentional miscut of the wafers. Additionally, some surface roughness in the form of small pits is observed, possibly due to the fact that the surface treatments (H-etching and UHV annealing) having been performed in separate vacuum chambers with an intervening transfer through air. Field-effect transistors have been fabricated with our graphene layers; they show a relatively strong held effect at room temperature, with an electron mobility of 535 cm 2/Vs. This value is somewhat lower than that believed to be theoretically possible for this material, and one possible reason may be the nonideal morphology of the surface (i.e. because of the observed steps and pits). Tunneling spectra of the graphene reveal semi-metallic behavior, consistent with that theoretically expected for an isolated layer of graphene. However, additional discrete states are observed in the spectra, possibly arising from bonding at the graphene/SiC interface. The observation of these states provides important input towards an eventual determination of the complete interface structure, and additionally, such states may be relevant in determining the electron mobility of the graphene. Stepped vicinal SIC{0001} substrates are useful templates for epitaxial growth of various types of layers: thick layers of compound semiconductor (in which the steps help preserving the stacking arrangement in the overlayer), monolayers of graphene, or submonolayer semiconductor layers that form quantum wires along the step edges. Step array produced by H-etching of vicinal SiC (0001) and (0001¯) with various miscut angles have been studied by AFM. H-etching is found to produce full unit-cell-high steps on the (0001) Si-face surfaces, but half unit-cell-high steps on the (0001¯) C-face surfaces. These observations are consistent with an asymmetry in the surface energy (i.e. etch rate) of the two types of step terminations occurring on the different surfaces. For high miscut angles, facet formation is observed on the vicinal Si-face, but less so on the C-face. This difference is interpreted in terms of a lower surface energy of the C-face. In terms of applying the stepped surfaces as a template, a much better uniformity in the step-step separation is found for the C-face surfaces.

UV-LIGA microfabrication process for sub-terahertz waveguides utilizing multiple layered SU-8 photoresist

NASA Astrophysics Data System (ADS)

Malekabadi, Ali; Paoloni, Claudio

2016-09-01

A microfabrication process based on UV LIGA (German acronym of lithography, electroplating and molding) is proposed for the fabrication of relatively high aspect ratio sub-terahertz (100-1000 GHz) metal waveguides, to be used as a slow wave structure in sub-THz vacuum electron devices. The high accuracy and tight tolerances required to properly support frequencies in the sub-THz range can be only achieved by a stable process with full parameter control. The proposed process, based on SU-8 photoresist, has been developed to satisfy high planar surface requirements for metal sub-THz waveguides. It will be demonstrated that, for a given thickness, it is more effective to stack a number of layers of SU-8 with lower thickness rather than using a single thick layer obtained at lower spin rate. The multiple layer approach provides the planarity and the surface quality required for electroforming of ground planes or assembly surfaces and for assuring low ohmic losses of waveguides. A systematic procedure is provided to calculate soft and post-bake times to produce high homogeneity SU-8 multiple layer coating as a mold for very high quality metal waveguides. A double corrugated waveguide designed for 0.3 THz operating frequency, to be used in vacuum electronic devices, was fabricated as test structure. The proposed process based on UV LIGA will enable low cost production of high accuracy sub-THz 3D waveguides. This is fundamental for producing a new generation of affordable sub-THz vacuum electron devices, to fill the technological gap that still prevents a wide diffusion of numerous applications based on THz radiation.

A comprehensive sensitivity analysis of the WRF model for air quality applications over the Iberian Peninsula

NASA Astrophysics Data System (ADS)

Borge, Rafael; Alexandrov, Vassil; José del Vas, Juan; Lumbreras, Julio; Rodríguez, Encarnacion

Meteorological inputs play a vital role on regional air quality modelling. An extensive sensitivity analysis of the Weather Research and Forecasting (WRF) model was performed, in the framework of the Integrated Assessment Modelling System for the Iberian Peninsula (SIMCA) project. Up to 23 alternative model configurations, including Planetary Boundary Layer schemes, Microphysics, Land-surface models, Radiation schemes, Sea Surface Temperature and Four-Dimensional Data Assimilation were tested in a 3 km spatial resolution domain. Model results for the most significant meteorological variables, were assessed through a series of common statistics. The physics options identified to produce better results (Yonsei University Planetary Boundary Layer, WRF Single-Moment 6-class microphysics, Noah Land-surface model, Eta Geophysical Fluid Dynamics Laboratory longwave radiation and MM5 shortwave radiation schemes) along with other relevant user settings (time-varying Sea Surface Temperature and combined grid-observational nudging) where included in a "best case" configuration. This setup was tested and found to produce more accurate estimation of temperature, wind and humidity fields at surface level than any other configuration for the two episodes simulated. Planetary Boundary Layer height predictions showed a reasonable agreement with estimations derived from routine atmospheric soundings. Although some seasonal and geographical differences were observed, the model showed an acceptable behaviour overall. Despite being useful to define the most appropriate setup of the WRF model for air quality modelling over the Iberian Peninsula, this study provides a general overview of WRF sensitivity and can constitute a reference for future mesoscale meteorological modelling exercises.

Effect of plasma ion bombardment on the reflectance of Io's trailing and leading hemispheres

NASA Technical Reports Server (NTRS)

Sack, N. J.; Baragiola, R. A.; Johnson, R. E.

1993-01-01

The possible effect of a net difference in the ion bombardment flux to the surface of Io on the ratio of the reflectance spectra is investigated. Io's vapor-deposited surface layers are simulated by a laboratory-produced film of vapor-deposited SO2 with a small admixture (about 3 percent) of H2S and (about 0.1 percent) H2O. It is shown that the reflectance ratio in the UV/visible of the surface bombarded by keV ions to the unbombarded surface is surprisingly similar to the observed ratio of Io's trailing to leading hemispherical reflectance. The changes produced are either structural or involve products of species originally present in the sample.

Interfacial stability of CoSi2/Si structures grown by molecular beam epitaxy

NASA Technical Reports Server (NTRS)

George, T.; Fathauer, R. W.

1992-01-01

The stability of CoSi2/Si interfaces was examined in this study using columnar silicide structures grown on (111) Si substrates. In the first set of experiments, Co and Si were codeposited using MBE at 800 C and the resulting columnar silicide layer was capped by epitaxial Si. Deposition of Co on the surface of the Si capping layer at 800 C results in the growth of the buried silicide columns. The buried columns grow by subsurface diffusion of the deposited Co, suppressing the formation of surface islands of CoSi2. The column sidewalls appear to be less stable than the top and bottom interfaces, resulting in preferential lateral growth and ultimately in the coalescence of the columns to form a continuous buried CoSi2 layer. In the second set of experiments, annealing of a 250 nm-thick buried columnar layer at 1000 C under a 100 nm-thick Si capping layer results in the formation of a surface layer of CoSi2 with a reduction in the sizes of the CoSi2 columns. For a sample having a thicker Si capping layer the annealing leads to Ostwald ripening producing buried equiaxed columns. The high CoSi2/Si interfacial strain could provide the driving force for the observed behavior of the buried columns under high-temperature annealing.

Nano-engineering of superhydrophobic aluminum surfaces for anti-corrosion

NASA Astrophysics Data System (ADS)

Jeong, Chanyoung

Metal corrosion is a serious problem, both economically and operationally, for engineering systems such as aircraft, automobiles, pipelines, and naval vessels. In such engineering systems, aluminum is one of the primary materials of construction due to its light weight compared to steel and good general corrosion resistance. However, because of aluminum's relatively lower resistance to corrosion in salt water environments, protective measures such as thick coatings, paints, or cathodic protection must be used for satisfactory service life. Unfortunately, such anti-corrosion methods can create other concerns, such as environmental contamination, protection durability, and negative impact on hydrodynamic efficiency. Recently, a novel approach to preventing metal corrosion has emerged, using superhydrophobic surfaces. Superhydrophobic surfaces create a composite interface to liquid by retaining air within the surface structures, thus minimizing the direct contact of the liquid environment to the metal surface. The result is a highly non-wetting and anti-adherent surface that can offer other benefits such as biofouling resistance and hydrodynamic low friction. Prior research with superhydrophobic surfaces for corrosion applications was based on irregular surface roughening and/or chemical coatings, which resulted in random surface features, mostly on the micrometer scale. Such microscale surface roughness with poor controllability of structural dimensions and shapes has been a critical limitation to deeper understanding of the anti-corrosive effectiveness and optimized application of this approach. The research reported here provides a novel approach to producing controlled superhydrophobic nanostructures on aluminum that allows a systematic investigation of the superhydrophobic surface parameters on the corrosion resistance and hence can provide a route to optimization of the surface. Electrochemical anodization is used to controllably modulate the oxide layer thickness and pore dimensions at the aluminum surface. The results show that thicker oxide layers with larger pore sizes allow the nanostructured surface to retain more gas (air) and hence provide a more effective barrier to corrosion. The anodizing techniques are further advanced to design and produce hierarchical three-dimensional nanostructures for better retention of the gaseous barrier layer at the surface.

Diffusing, side-firing, and radial delivery laser balloon catheters for creating subsurface thermal lesions in tissue

NASA Astrophysics Data System (ADS)

Chang, Chun-Hung; Fried, Nathaniel M.

2016-02-01

Infrared lasers have been used in combination with applied cooling methods to preserve superficial skin layers during cosmetic surgery. Similarly, combined laser irradiation and tissue cooling may also allow development of minimally invasive laser therapies beyond dermatology. This study compares diffusing, side-firing, and radial delivery laser balloon catheter designs for creation of subsurface lesions in tissue, ex vivo, using a near-IR laser and applied contact cooling. An Ytterbium fiber laser with 1075 nm wavelength delivered energy through custom built 18 Fr (6-mm-OD) balloon catheters incorporating either 10-mm-long diffusing fiber tip, 90 degree side-firing fiber, or radial delivery cone mirror, through a central lumen. A chilled solution was flowed through a separate lumen into 9-mm-diameter balloon to keep probe cooled at 7°C. Porcine liver tissue samples were used as preliminary tissue model for immediate observation of thermal lesion creation. The diffusing fiber produced subsurface thermal lesions measuring 49.3 +/- 10.0 mm2 and preserved 0.8 +/- 0.1 mm of surface tissue. The side-firing fiber produced subsurface thermal lesions of 2.4 +/- 0.9 mm2 diameter and preserved 0.5 +/- 0.1 mm of surface tissue. The radial delivery probe assembly failed to produce subsurface thermal lesions, presumably due to the small effective spot diameter at the tissue surface, which limited optical penetration depth. Optimal laser power and irradiation time measured 15 W and 100 s for diffusing fiber and 1.4 W and 20 s, for side-firing fiber, respectively. Diffusing and side-firing laser balloon catheter designs provided subsurface thermal lesions in tissue. However, the divergent laser beam in both designs limited the ability to preserve a thicker layer of tissue surface. Further optimization of laser and cooling parameters may be necessary to preserve thicker surface tissue layers.

Patterned structures of graphene and graphitic carbon and methods for their manufacture

DOEpatents

Polsky, Ronen; Xiao, Xiaoyin; Burckel, David Bruce; Wheeler, David R.; Brozik, Susan M.; Beechem, Thomas Edwin

2017-01-03

A patterned graphene or graphitic body is produced by providing a three-dimensionally patterned carbonaceous body; coating the body with a catalytic metal whereby is formed a coating having an inner surface proximal the body and an outer surface distal the body; and annealing the coated body under time and temperature conditions effective to form a graphene or graphitic layer on the outer surface of the catalytic metal coating.

Patterned structures of graphene and graphitic carbon and methods for their manufacture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Polsky, Ronen; Xiao, Xiaoyin; Burckel, David Bruce

A patterned graphene or graphitic body is produced by providing a three-dimensionally patterned carbonaceous body; coating the body with a catalytic metal whereby is formed a coating having an inner surface proximal the body and an outer surface distal the body; and annealing the coated body under time and temperature conditions effective to form a graphene or graphitic layer on the outer surface of the catalytic metal coating.

Method for producing high quality oxide films on substrates

DOEpatents

Ruckman, Mark W.; Strongin, Myron; Gao, Yong L.

1993-01-01

A method for providing an oxide film of a material on the surface of a substrate using a reactive deposition of the material onto the substrate surface in the presence of a solid or liquid layer of an oxidizing gas. The oxidizing gas is provided on the substrate surface in an amount sufficient to dissipate the latent heat of condensation occurring during deposition as well as creating a favorable oxidizing environment for the material.

Introduction to boundary-layer theory. [viscous friction loss calculation for turbine blade design

NASA Technical Reports Server (NTRS)

Mcnally, W. D.

1973-01-01

The pressure ratio across a turbine provides a certain amount of ideal energy that is available to the turbine for producing work. The portion of the ideal energy that is not converted to work is considered to be a loss. One of the more important and difficult aspects of turbine design is the prediction of the losses. The primary cause of losses is the boundary layer that develops on the blade and end wall surfaces. Boundary-layer theory is used to calculate the parameters needed to estimate viscous (friction) losses.

Multi-technique characterization of gold electroplating on silver substrates for cultural heritage applications

NASA Astrophysics Data System (ADS)

Ortega-Feliu, I.; Ager, F. J.; Roldán, C.; Ferretti, M.; Juanes, D.; Scrivano, S.; Respaldiza, M. A.; Ferrazza, L.; Traver, I.; Grilli, M. L.

2017-09-01

This work presents a detailed study of a series of silver plates gilded via electroplating techniques in which the characteristics of the coating gold layers are investigated as a function of the electroplating variables (voltage, time, anode surface and temperature). Some reference samples were coated by radio frequency sputtering in order to compare gold layer homogeneity and effective density. Surface analysis was performed by means of atomic and nuclear techniques (SEM-EDX, EDXRF, PIXE and RBS) to obtain information about thickness, homogeneity, effective density, profile concentration of the gold layers and Au-Ag diffusion profiles. The gold layer thickness obtained by PIXE and EDXRF is consistent with the thickness obtained by means of RBS depth profiling. Electroplated gold mass thickness increases with electroplating time, anode area and voltage. However, electrodeposited samples present rough interfaces and gold layer effective densities lower than the nominal density of Au (19.3 g/cm3), whereas sputtering produces uniform layers with nominal density. These analyses provide valuable information to historians and curators and can help the restoration process of gold-plated silver objects.

Epoxy resin reinforced with nanothin polydopamine-coated carbon nanotubes: a study of the interfacial polymer layer thickness

DOE PAGES

Ling, Yang; Li, Weizhen; Wang, Baoyu; ...

2016-03-29

Carbon nanotubes (CNTs) functionalized by a nanothin poly(dopamine) (PDA) layer were produced by a one-pot, nondestructive approach, with direct polymerization of dopamine on the CNT surface. The thickness of the PDA layer can be well-controlled by the reaction time and the proportion of dopamine, and this thickness is found to be the key factor in controlling the dispersion of CNTs and the extent of the interfacial interactions between the CNT@PDA and epoxy resin. SEM results indicated that the dispersion of CNTs in epoxy was improved significantly by coating a nanothin PDA layer onto the CNT surface. In agreeme nt withmore » this finding, the CNTs functionalized with the thinnest PDA layer provided the best mechanical and thermal properties. This result confirmed that a thinner PDA layer could provide optimized interfacial interactions between the CNT@PDA and epoxy matrix and weaken the self-agglomeration of CNTs, which led to an improved effective stress and heat transfer between the CNTs and the polymer matrix.« less

Thermo-stable carbon nanotube-TiO₂ nanocompsite as electron highways in dye-sensitized solar cell produced by bio-nano-process.

PubMed

Inoue, Ippei; Yamauchi, Hirofumi; Okamoto, Naofumi; Toyoda, Kenichi; Horita, Masahiro; Ishikawa, Yasuaki; Yasueda, Hisashi; Uraoka, Yukiharu; Yamashita, Ichiro

2015-07-17

We produced a thermostable TiO2-(anatase)-coated multi-walled-carbon-nanotube (MWNT) nanocomposite for use in dye-sensitized solar cells (DSSCs) using biological supuramolecules as catalysts. We synthesized two different sizes of iron oxide nanoparticles (NPs) and arrayed the NPs on a silicon substrate utilizing two kinds of genetically modified cage-shaped proteins with silicon-binding peptide aptamers on their outer surfaces. Chemical vapor deposition (CVD) with the vapor-liquid-solid phase (VLS) method was applied to the substrate, and thermostable MWNTs with a diameter of 6 ± 1 nm were produced. Using a genetically modified cage-shaped protein with carbon-nanomaterials binding and Ti-mineralizing peptides as a catalyst, we were able to mineralize a titanium compound around the surface of the MWNT. The products were sintered, and thin TiO2-layer-coated MWNTs nanocomoposites were successfully produced. Addition of a 0.2 wt% TiO2-coated MWNT nanocomposite to a DSSC photoelectrode improved current density by 11% and decreased electric resistance by 20% compared to MWNT-free reference DSSCs. These results indicate that a nanoscale TiO2-layer-coated thermostable MWNT structure produced by our mutant proteins works as a superior electron transfer highway within TiO2 photoelectrodes.

Thermo-stable carbon nanotube-TiO2 nanocompsite as electron highways in dye-sensitized solar cell produced by bio-nano-process

NASA Astrophysics Data System (ADS)

Inoue, Ippei; Yamauchi, Hirofumi; Okamoto, Naofumi; Toyoda, Kenichi; Horita, Masahiro; Ishikawa, Yasuaki; Yasueda, Hisashi; Uraoka, Yukiharu; Yamashita, Ichiro

2015-07-01

We produced a thermostable TiO2-(anatase)-coated multi-walled-carbon-nanotube (MWNT) nanocomposite for use in dye-sensitized solar cells (DSSCs) using biological supuramolecules as catalysts. We synthesized two different sizes of iron oxide nanoparticles (NPs) and arrayed the NPs on a silicon substrate utilizing two kinds of genetically modified cage-shaped proteins with silicon-binding peptide aptamers on their outer surfaces. Chemical vapor deposition (CVD) with the vapor-liquid-solid phase (VLS) method was applied to the substrate, and thermostable MWNTs with a diameter of 6 ± 1 nm were produced. Using a genetically modified cage-shaped protein with carbon-nanomaterials binding and Ti-mineralizing peptides as a catalyst, we were able to mineralize a titanium compound around the surface of the MWNT. The products were sintered, and thin TiO2-layer-coated MWNTs nanocomoposites were successfully produced. Addition of a 0.2 wt% TiO2-coated MWNT nanocomposite to a DSSC photoelectrode improved current density by 11% and decreased electric resistance by 20% compared to MWNT-free reference DSSCs. These results indicate that a nanoscale TiO2-layer-coated thermostable MWNT structure produced by our mutant proteins works as a superior electron transfer highway within TiO2 photoelectrodes.

Passivation of InGaAs(001)-(2 × 4) by Self-Limiting Chemical Vapor Deposition of a Silicon Hydride Control Layer.

PubMed

Edmonds, Mary; Kent, Tyler; Chagarov, Evgueni; Sardashti, Kasra; Droopad, Ravi; Chang, Mei; Kachian, Jessica; Park, Jun Hong; Kummel, Andrew

2015-07-08

A saturated Si-Hx seed layer for gate oxide or contact conductor ALD has been deposited via two separate self-limiting and saturating CVD processes on InGaAs(001)-(2 × 4) at substrate temperatures of 250 and 350 °C. For the first self-limiting process, a single silicon precursor, Si3H8, was dosed at a substrate temperature of 250 °C, and XPS results show the deposited silicon hydride layer saturated at about 4 monolayers of silicon coverage with hydrogen termination. STS results show the surface Fermi level remains unpinned following the deposition of the saturated silicon hydride layer, indicating the InGaAs surface dangling bonds are electrically passivated by Si-Hx. For the second self-limiting process, Si2Cl6 was dosed at a substrate temperature of 350 °C, and XPS results show the deposited silicon chloride layer saturated at about 2.5 monolayers of silicon coverage with chlorine termination. Atomic hydrogen produced by a thermal gas cracker was subsequently dosed at 350 °C to remove the Si-Cl termination by replacing with Si-H termination as confirmed by XPS, and STS results confirm the saturated Si-Hx bilayer leaves the InGaAs(001)-(2 × 4) surface Fermi level unpinned. Density function theory modeling of silicon hydride surface passivation shows an Si-Hx monolayer can remove all the dangling bonds and leave a charge balanced surface on InGaAs.

Aerosols attenuating the solar radiation collected by solar tower plants: The horizontal pathway at surface level

NASA Astrophysics Data System (ADS)

Elias, Thierry; Ramon, Didier; Dubus, Laurent; Bourdil, Charles; Cuevas-Agulló, Emilio; Zaidouni, Taoufik; Formenti, Paola

2016-05-01

Aerosols attenuate the solar radiation collected by solar tower plants (STP), along two pathways: 1) the atmospheric column pathway, between the top of the atmosphere and the heliostats, resulting in Direct Normal Irradiance (DNI) changes; 2) the grazing pathway close to surface level, between the heliostats and the optical receiver. The attenuation along the surface-level grazing pathway has been less studied than the aerosol impact on changes of DNI, while it becomes significant in STP of 100 MW or more. Indeed aerosols mostly lay within the surface atmospheric layer, called the boundary layer, and the attenuation increases with the distance covered by the solar radiation in the boundary layer. In STP of 100 MW or more, the distance between the heliostats and the optical receiver becomes large enough to produce a significant attenuation by aerosols. We used measured aerosol optical thickness and computed boundary layer height to estimate the attenuation of the solar radiation at surface level at Ouarzazate (Morocco). High variabilities in aerosol amount and in vertical layering generated a significant magnitude in the annual cycle and significant inter-annual changes. Indeed the annual mean of the attenuation caused by aerosols over a 1-km heliostat-receiver distance was 3.7% in 2013, and 5.4% in 2014 because of a longest desert dust season. The monthly minimum attenuation of less than 3% was observed in winter and the maximum of more than 7% was observed in summer.

THE ROLE OF WATER IN PROTOPLASMIC PERMEABILITY AND IN ANTAGONISM

PubMed Central

Osterhout, W. J. V.

1956-01-01

The behavior of the cell depends to a large extent on the permeability of the outer non-aqueous surface layer of the protoplasm. This layer is immiscible with water but may be quite permeable to it. It seems possible that a reversible increase or decrease in permeability may be due to a corresponding increase or decrease in the water content of the non-aqueous surface layer. Irreversible increase in permeability need not be due primarily to increase in the water content of the surface layer but may be caused chiefly by changes in the protoplasm on which the surface layer rests. It may include desiccation, precipitation, and other alterations. An artificial cell is described in which the outer protoplasmic surface layer is represented by a layer of guaiacol on one side of which is a solution of KOH + KCl representing the external medium and on the other side is a solution of CO2 representing the protoplasm. The K+ unites with guaiacol and diffuses across to the artificial protoplasm where its concentration becomes higher than in the external solution. The guaiacol molecule thus acts as a carrier molecule which transports K+ from the external medium across the protoplasmic surface. The outer part of the protoplasm may contain relatively few potassium ions so that the outwardly directed potential at the outer protoplasmic surface may be small but the inner part of the protoplasm may contain more potassium ions. This may happen when potassium enters in combination with carrier molecules which do not completely dissociate until they reach the vacuole. Injury and recovery from injury may be studied by measuring the movements of water into and out of the cell. Metabolism by producing CO2 and other acids may lower the pH and cause local shrinkage of the protoplasm which may lead to protoplasmic motion. Antagonism between Na+ and Ca++ appears to be due to the fact that in solutions of NaCl the surface layer takes up an excessive amount of water and this may be prevented by the addition of suitable amounts of CaCl2. In Nitella the outer non-aqueous surface layer may be rendered irreversibly permeable by sharply bending the cell without permanent damage to the inner non-aqueous surface layer surrounding the vacuole. The formation of contractile vacuoles may be imitated in non-living systems. An extract of the sperm of the marine worm Nereis which contains a highly surface-active substance can cause the egg to divide. It seems possible that this substance may affect the surface layer of the egg and cause it to take up water. A surface-active substance has been found in all the seminal fluids examined including those of trout, rooster, bull, and man. Duponol which is highly surface-active causes the protoplasm of Spirogyra to take up water and finally dissolve but it can be restored to the gel state by treatment with Lugol solution (KI + I). The transition from gel to sol and back again can be repeated many times in succession. The behavior of water in the surface layer of the protoplasm presents important problems which deserve careful examination. PMID:13346047

Photoluminescence emission of nanoporous anodic aluminum oxide films prepared in phosphoric acid

PubMed Central

2012-01-01

The photoluminescence emission of nanoporous anodic aluminum oxide films formed in phosphoric acid is studied in order to explore their defect-based subband electronic structure. Different excitation wavelengths are used to identify most of the details of the subband states. The films are produced under different anodizing conditions to optimize their emission in the visible range. Scanning electron microscopy investigations confirm pore formation in the produced layers. Gaussian analysis of the emission data indicates that subband states change with anodizing parameters, and various point defects can be formed both in the bulk and on the surface of these nanoporous layers during anodizing. PMID:23272786

Preliminary Investigation of Surface Treatments to Enhance the Wear Resistance of 60-Nitinol

NASA Technical Reports Server (NTRS)

Stanford, Malcolm K.

2016-01-01

The use of protective surface treatments on 60-Nitinol (60wt%Ni-40wt%Ti) was studied. Various nitriding techniques as well as a (Ti, Al)N coating were evaluated visually, microscopically, and by hardness and scratch testing. The chemical composition of the surface treatments was investigated by x-ray techniques. The results indicate that very hard (greater than 1,000 HK) and adherent surface layers can be produced on 60-Nitinol. Further work is needed to determine the tribological properties of these surface treatments in relevant operating environments.

Comparison of surface characteristics of retrieved cobalt-chromium femoral heads with and without ion implantation.

PubMed

McGrory, Brian J; Ruterbories, James M; Pawar, Vivek D; Thomas, Reginald K; Salehi, Abraham B

2012-01-01

Nitrogen ion implantation of CoCr is reported to produce increased surface hardness and a lower friction surface. Femoral heads with and without ion implantation retrieved from 1997 to 2003 were evaluated for surface roughness (average surface roughness [Ra], mean peak height [Rpm], and maximum distance from peak to valley [Rmax]), nanohardness, and the ion-treated layer thickness. The difference in average Rmax (P = .033) and average Rpm (P = .008) was statistically significant, but there was no correlation between the average or maximum roughness parameters (average surface roughness, Rmax, and Rpm) and time in vivo (P > .05). Overall, nanohardness was greater for the low-friction ion-treated heads (P < .001); and it decreased with increasing time in vivo (P = .01). Ion treatment produces an increased surface hardness, but the advantage of this increased hardness appears to dissipate over time in vivo. Copyright © 2012 Elsevier Inc. All rights reserved.

Method of depositing multi-layer carbon-based coatings for field emission

DOEpatents

Sullivan, John P.; Friedmann, Thomas A.

1999-01-01

A novel field emitter device for cold cathode field emission applications, comprising a multi-layer resistive carbon film. The multi-layered film of the present invention is comprised of at least two layers of a resistive carbon material, preferably amorphous-tetrahedrally coordinated carbon, such that the resistivities of adjacent layers differ. For electron emission from the surface, the preferred structure comprises a top layer having a lower resistivity than the bottom layer. For edge emitting structures, the preferred structure of the film comprises a plurality of carbon layers, wherein adjacent layers have different resistivities. Through selection of deposition conditions, including the energy of the depositing carbon species, the presence or absence of certain elements such as H, N, inert gases or boron, carbon layers having desired resistivities can be produced. Field emitters made according the present invention display improved electron emission characteristics in comparison to conventional field emitter materials.

Method of depositing multi-layer carbon-based coatings for field emission

DOEpatents

Sullivan, J.P.; Friedmann, T.A.

1999-08-10

A novel field emitter device is disclosed for cold cathode field emission applications, comprising a multi-layer resistive carbon film. The multi-layered film of the present invention is comprised of at least two layers of a resistive carbon material, preferably amorphous-tetrahedrally coordinated carbon, such that the resistivities of adjacent layers differ. For electron emission from the surface, the preferred structure comprises a top layer having a lower resistivity than the bottom layer. For edge emitting structures, the preferred structure of the film comprises a plurality of carbon layers, wherein adjacent layers have different resistivities. Through selection of deposition conditions, including the energy of the depositing carbon species, the presence or absence of certain elements such as H, N, inert gases or boron, carbon layers having desired resistivities can be produced. Field emitters made according the present invention display improved electron emission characteristics in comparison to conventional field emitter materials. 8 figs.

Impact of the exopolysaccharide layer on biofilms, adhesion and resistance to stress in Lactobacillus johnsonii FI9785.

PubMed

Dertli, Enes; Mayer, Melinda J; Narbad, Arjan

2015-02-04

The bacterial cell surface is a crucial factor in cell-cell and cell-host interactions. Lactobacillus johnsonii FI9785 produces an exopolysaccharide (EPS) layer whose quantity and composition is altered in mutants that harbour genetic changes in their eps gene clusters. We have assessed the effect of changes in EPS production on cell surface characteristics that may affect the ability of L. johnsonii to colonise the poultry host and exclude pathogens. Analysis of physicochemical cell surface characteristics reflected by Zeta potential and adhesion to hexadecane showed that an increase in EPS gave a less negative, more hydrophilic surface and reduced autoaggregation. Autoaggregation was significantly higher in mutants that have reduced EPS, indicating that EPS can mask surface structures responsible for cell-cell interactions. EPS also affected biofilm formation, but here the quantity of EPS produced was not the only determinant. A reduction in EPS production increased bacterial adhesion to chicken gut explants, but made the bacteria less able to survive some stresses. This study showed that manipulation of EPS production in L. johnsonii FI9785 can affect properties which may improve its performance as a competitive exclusion agent, but that positive changes in adhesion may be compromised by a reduction in the ability to survive stress.

Superficial Macromolecular Arrays on the Cell Wall of Spirillum putridiconchylium

PubMed Central

Beveridge, T. J.; Murray, R. G. E.

1974-01-01

Electron microscopy of the cell envelope of Spirillum putridiconchylium, using negatively stained, thin-sectioned, and replicated freeze-etched preparations, showed two superficial wall layers forming a complex macromolecular pattern on the external surface. The outer structured layer was a linear array of particles overlying an inner tetragonal array of larger subunits. They were associated in a very regular fashion, and the complex was bonded to the outer, pitted surface of the lipopolysaccharide tripartite layer of the cell wall. The relationship of the components of the two structured layers was resolved with the aid of optical diffraction, combined with image filtering and reconstruction and linear and rotary integration techniques. The outer structural layer consisted of spherical 1.5-nm units set in double lines determined by the size and arrangement of 6- by 3-nm inner structural layer subunits, which bore one outer structural layer unit on each outer corner. The total effect of this arrangement was a double-ridged linear structure that was evident in surface replicas and negatively stained fragments of the whole wall. The packing of these units was not square but skewed by 2° off the perpendicular so that the “unit array” described by optical diffraction and linear integration appeared to be a deformed tetragon. The verity of the model was checked by using a photographically reduced image to produce an optical diffraction pattern for comparison with that of the actual layers. The correspondence was nearly perfect. Images PMID:4137219

Carburizing treatment of low alloy steels: Effect of technological parameters

NASA Astrophysics Data System (ADS)

Benarioua, Younes

2018-05-01

The surface areas of the parts subjected to mechanical loads influence to a great extent the resistance to wear and fatigue. In majority of cases, producing of a hard superficial layer on a tough substrate is conducive to an increased resistance to mechanical wear and fatigue. Cementation treatment of low alloy steels which bonds superficial martensitic layer of high hardness and lateral compressive to a core of lower hardness and greater toughness is an example of a good solution of the problem. The high hardness of the martensitic layer is due to an increased concentration of interstitial carbon atoms in the austenite before quenching. The lower hardness of the core after quenching is due to the presence of ferrite and pearlite components which appear if the cooling rate after austenitization becomes lower than the critical on. The objective of the present study was to obtain a cemented surface layer on low alloy steel by means of pack carburizing treatment. Different steel grades, austenitization temperatures as well as different soaking times were used as parameters of the pack carburizing treatment. During this treatment, carbon atoms from the pack powder diffuse toward the steels surface and form compounds of iron carbides. The effect of carburizing parameters on the transformation rate of low carbon surface layer of the low alloy steel to the cemented one was investigated by several analytical techniques.

Enhancing the Hardness of Sintered SS 17-4PH Using Nitriding Process for Bracket Orthodontic Application

NASA Astrophysics Data System (ADS)

Suharno, B.; Supriadi, S.; Ayuningtyas, S. T.; Widjaya, T.; Baek, E. R.

2018-01-01

Brackets orthodontic create teeth movement by applying force from wire to bracket then transferred to teeth. However, emergence of friction between brackets and wires reduces load for teeth movement towards desired area. In order to overcome these problem, surface treatment like nitriding chosen as a process which could escalate efficiency of transferred force by improving material hardness since hard materials have low friction levels. This work investigated nitriding treatment to form nitride layer which affecting hardness of sintered SS 17-4PH. The nitride layers produced after nitriding process at various temperature i.e. 470°C, 500°C, 530°C with 8hr holding time under 50% NH3 atmosphere. Optical metallography was conducted to compare microstructure of base and surface metal while the increasing of surface hardness then observed using vickers microhardness tester. Hardened surface layer was obtained after gaseous nitriding process because of nitride layer that contains Fe4N, CrN and Fe-αN formed. Hardness layers can achieved value 1051 HV associated with varies thickness from 53 to 119 μm. The presence of a precipitation process occurring in conjunction with nitriding process can lead to a decrease in hardness due to nitrogen content diminishing in solid solution phase. This problem causes weakening of nitrogen expansion in martensite lattice.

Atomic composition and electrical characteristics of epitaxial CVD diamond layers doped with boron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Surovegina, E. A., E-mail: suroveginaka@ipmras.ru; Demidov, E. V.; Drozdov, M. N.

2016-12-15

The results of analysis of the atomic composition, doping level, and hole mobility in epitaxial diamond layers when doped with boron are reported. The layers are produced by chemical-vapor deposition. The possibilities of uniform doping with boron to a level in the range 5 × 10{sup 17} to ~10{sup 20} at cm{sup –3} and of δ doping to the surface concentration (0.3–5) × 10{sup 13} at cm{sup –3} are shown. The conditions for precision ion etching of the structures are determined, and barrier and ohmic contacts to the layers are formed.

Development of a Flow Field for Testing a Boundary-Layer-Ingesting Propulsor

NASA Technical Reports Server (NTRS)

Hirt, Stefanie M.; Arend, David J.; Wolter, John D.

2017-01-01

The test section of the 8- by 6-Foot Supersonic Wind Tunnel at NASA Glenn Research Center was modified to produce the test conditions for a boundary-layer-ingesting propulsor. A test was conducted to measure the flow properties in the modified test section before the propulsor was installed. Measured boundary layer and freestream conditions were compared to results from computational fluid dynamics simulations of the external surface for the reference vehicle. Testing showed that the desired freestream conditions and boundary layer thickness could be achieved; however, some non-uniformity of the freestream conditions, particularly the total temperature, were observed.

A theoretical study of symmetry-breaking organic overlayers on single- and bi-layer graphene

NASA Astrophysics Data System (ADS)

Morales-Cifuentes, Josue; Einstein, T. L.

2013-03-01

An ``overlayer'' of molecules that breaks the AB symmetry of graphene can produce (modify) a band gap in single- (bi-) layer graphene.[2] Since the triangular shaped trimesic acid (TMA) molecule forms two familiar symmetry breaking configurations, we are motivated to model TMA physisorption on graphene surfaces in conjunction with experiments by Groce et al. at UMD. Using VASP, with ab initio van der Waals density functionals (vdW-DF), we simulate adsorption of TMA onto a graphene surface in several symmetry-breaking arrangements in order to predict/understand the effect of TMA adsorption on experimental observables. Supported by NSF-MRSEC Grant DMR 05-20471.

Effects of different wetting layers on the growth of smooth ultra-thin silver thin films

NASA Astrophysics Data System (ADS)

Ni, Chuan; Shah, Piyush; Sarangan, Andrew M.

2014-09-01

Ultrathin silver films (thickness below 10 nm) are of great interest as optical coatings on windows and plasmonic devices. However, producing these films has been a continuing challenge because of their tendency to form clusters or islands rather than smooth contiguous thin films. In this work we have studied the effect of Cu, Ge and ZnS as wetting layers (1.0 nm) to achieve ultrasmooth thin silver films. The silver films (5 nm) were grown by RF sputter deposition on silicon and glass substrates using a few monolayers of the different wetting materials. SEM imaging was used to characterize the surface properties such as island formation and roughness. Also the optical properties were measured to identify the optical impact of the different wetting layers. Finally, a multi-layer silver based structure is designed and fabricated, and its performance is evaluated. The comparison between the samples with different wetting layers show that the designs with wetting layers which have similar optical properties to silver produce the best overall performance. In the absence of a wetting layer, the measured optical spectra show a significant departure from the model predictions, which we attribute primarily to the formation of clusters.

Counter-intuitive features of the dynamic topography unveiled by tectonically realistic 3D numerical models of mantle-lithosphere interactions

NASA Astrophysics Data System (ADS)

Burov, Evgueni; Gerya, Taras

2013-04-01

It has been long assumed that the dynamic topography associated with mantle-lithosphere interactions should be characterized by long-wavelength features (> 1000 km) correlating with morphology of mantle flow and expanding beyond the scale of tectonic processes. For example, debates on the existence of mantle plumes largely originate from interpretations of expected signatures of plume-induced topography that are compared to the predictions of analytical and numerical models of plume- or mantle-lithosphere interactions (MLI). Yet, most of the large-scale models treat the lithosphere as a homogeneous stagnant layer. We show that in continents, the dynamic topography is strongly affected by rheological properties and layered structure of the lithosphere. For that we reconcile mantle- and tectonic-scale models by introducing a tectonically realistic continental plate model in 3D large-scale plume-mantle-lithosphere interaction context. This model accounts for stratified structure of continental lithosphere, ductile and frictional (Mohr-Coulomb) plastic properties and thermodynamically consistent density variations. The experiments reveal a number of important differences from the predictions of the conventional models. In particular, plate bending, mechanical decoupling of crustal and mantle layers and intra-plate tension-compression instabilities result in transient topographic signatures such as alternating small-scale surface features that could be misinterpreted in terms of regional tectonics. Actually thick ductile lower crustal layer absorbs most of the "direct" dynamic topography and the features produced at surface are mostly controlled by the mechanical instabilities in the upper and intermediate crustal layers produced by MLI-induced shear and bending at Moho and LAB. Moreover, the 3D models predict anisotropic response of the lithosphere even in case of isotropic solicitations by axisymmetric mantle upwellings such as plumes. In particular, in presence of small (i.e. insufficient to produce solely any significant deformation) uniaxial extensional tectonic stress field, the plume-produced surface and LAB features have anisotropic linear shapes perpendicular to the far-field tectonic forces, typical for continental rifts. Compressional field results in singular sub-linear folds above the plume head, perpendicular to the direction of compression. Small bi-axial tectonic stress fields (compression in one direction and extension in the orthogonal direction) result in oblique, almost linear segmented normal or inverse faults with strike-slip components (or visa verse , strike-slip faults with normal or inverse components)

Optimization of the Silver Nanoparticles PEALD Process on the Surface of 1-D Titania Coatings

PubMed Central

Radtke, Aleksandra; Kozak, Wiesław; Sadowska, Beata; Więckowska-Szakiel, Marzena; Talik, Ewa; Mäkelä, Maarit; Leskelä, Markku; Piszczek, Piotr

2017-01-01

Plasma enhanced atomic layer deposition (PEALD) of silver nanoparticles on the surface of 1-D titania coatings, such as nanotubes (TNT) and nanoneedles (TNN), has been carried out. The formation of TNT and TNN layers enriched with dispersed silver particles of strictly defined sizes and the estimation of their bioactivity was the aim of our investigations. The structure and the morphology of produced materials were determined using X-ray photoelectron spectroscopy (XPS) and scanning electron miscroscopy (SEM). Their bioactivity and potential usefulness in the modification of implants surface have been estimated on the basis of the fibroblasts adhesion and proliferation assays, and on the basis of the determination of their antibacterial activity. The cumulative silver release profiles have been checked with the use of inductively coupled plasma-mass spectrometry (ICPMS), in order to exclude potential cytotoxicity of silver decorated systems. Among the studied nanocomposite samples, TNT coatings, prepared at 3, 10, 12 V and enriched with silver nanoparticles produced during 25 cycles of PEALD, revealed suitable biointegration properties and may actively counteract the formation of bacterial biofilm. PMID:28737725

Microstructure and mechanical properties of Al/Cu/Mg laminated composite sheets produced by the ARB proces

NASA Astrophysics Data System (ADS)

Rahmatabadi, Davood; Tayyebi, Moslem; Hashemi, Ramin; Faraji, Ghader

2018-05-01

In the present study, an Al/Cu/Mg multi-layered composite was produced by accumulative roll bonding (ARB) through seven passes, and its microstructure and mechanical properties were evaluated. The microstructure investigations show that plastic instability occurred in both the copper and magnesium reinforcements in the primary sandwich. In addition, a composite with a perfectly uniform distribution of copper and magnesium reinforcing layers was produced during the last pass. By increasing the number of ARB cycles, the microhardness of the layers including aluminum, copper, and magnesium was significantly increased. The ultimate tensile strength of the sandwich was enhanced continually and reached a maximum value of 355.5 MPa. This strength value was about 3.2, 2, and 2.1 times higher than the initial strength values for the aluminum, copper, and magnesium sheets, respectively. Investigation of tensile fracture surfaces during the ARB process indicated that the fracture mechanism changed to shear ductile at the seventh pass.

Structure and properties of nitrided surface layer produced on NiTi shape memory alloy by low temperature plasma nitriding

NASA Astrophysics Data System (ADS)

Czarnowska, Elżbieta; Borowski, Tomasz; Sowińska, Agnieszka; Lelątko, Józef; Oleksiak, Justyna; Kamiński, Janusz; Tarnowski, Michał; Wierzchoń, Tadeusz

2015-04-01

NiTi shape memory alloys are used for bone and cardiological implants. However, on account of the metallosis effect, i.e. the release of the alloy elements into surrounding tissues, they are subjected to various surface treatment processes in order to improve their corrosion resistance and biocompatibility without influencing the required shape memory properties. In this paper, the microstructure, topography and morphology of TiN surface layer on NiTi alloy, and corrosion resistance, both before and after nitriding in low-temperature plasma at 290 °C, are presented. Examinations with the use of the potentiodynamic and electrochemical impedance spectroscopy methods were carried out and show an increase of corrosion resistance in Ringer's solution after glow-discharge nitriding. This surface titanium nitride layer also improved the adhesion of platelets and the proliferation of osteoblasts, which was investigated in in vitro experiments with human cells. Experimental data revealed that nitriding NiTi shape memory alloy under low-temperature plasma improves its properties for bone implant applications.

Geological evidence for solid-state convection in Europa's ice shell.

PubMed

Pappalardo, R T; Head, J W; Greeley, R; Sullivan, R J; Pilcher, C; Schubert, G; Moore, W B; Carr, M H; Moore, J M; Belton, M J; Goldsby, D L

1998-01-22

The ice-rich surface of the jovian satellite Europa is sparsely cratered, suggesting that this moon might be geologically active today. Moreover, models of the satellite's interior indicate that tidal interactions with Jupiter might produce enough heat to maintain a subsurface liquid water layer. But the mechanisms of interior heat loss and resurfacing are currently unclear, as is the question of whether Europa has (or had at one time) a liquid water ocean. Here we report on the morphology and geological interpretation of distinct surface features-pits, domes and spots-discovered in high-resolution images of Europa obtained by the Galileo spacecraft. The features are interpreted as the surface manifestation of diapirs, relatively warm localized ice masses that have risen buoyantly through the subsurface. We find that the formation of the features can be explained by thermally induced solid-state convection within an ice shell, possibly overlying a liquid water layer. Our results are consistent with the possibility that Europa has a liquid water ocean beneath a surface layer of ice, but further tests and observations are needed to demonstrate this conclusively.

Geological evidence for solid-state convection in Europa's ice shell

USGS Publications Warehouse

Pappalardo, R.T.; Head, J.W.; Greeley, R.; Sullivan, R.J.; Pilcher, C.; Schubert, G.; Moore, W.B.; Carr, M.H.; Moore, Johnnie N.; Belton, M.J.S.; Goldsby, D.L.

1998-01-01

The ice-rich surface of the jovian satellite Europa is sparsely cratered, suggesting that this moon might be geologically active today. Moreover, models of the satellite's interior indicate that tidal interactions with Jupiter might produce enough heat to maintain a subsurface liquid water layer. But the mechanisms of interior heat loss and resurfacing are currently unclear, as is the question of whether Europa has (or had at one time) a liquid water ocean. Here we report on the morphology and geological interpretation of distinct surface features-pits, domes and spots-discovered in high-resolution images of Europa obtained by the Galileo spacecraft. The features are interpreted as the surface manifestation of diapirs, relatively warm localized ice masses that have risen buoyantly through the subsurface. We find that the formation of the features can be explained by thermally induced solid-state convection within an ice shell, possibly overlying a liquid water layer. Our results are consistent with the possibility that Europa has a liquid water ocean beneath a surface layer of ice, but further tests and observations are needed to demonstrate this conclusively.

O electrolyte for bio-application

NASA Astrophysics Data System (ADS)

Naddaf, M.; Almariri, A.

2014-09-01

Porous silicon (PS) has been prepared in the dark by anodic etching of n+-type (111) silicon substrate in a HF:HCl:C2H5OH:H2O2:H2O electrolyte. The processed PS layer is characterized by means of photoluminescence (PL) spectroscopy, scanning electron microscope (SEM), water contact angle (CA) measurements, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and micro-Raman scattering. The CA of fresh PS layer is found to be ~142°. On aging at ambient conditions, the CA decreases gently to reach ~133° after 3 month, and then it is stabilized for a prolonged time of aging. The visible PL emission from the PS layer also exhibits a good stability against aging time. The FTIR and XPS measurements and analysis show that the stable aged PS layer has rather SiO2-rich surface. The micro/nanostructure nature of the PS layer is revealed from SEM and micro-Raman results and correlated to CA results. Stable hydrophobic surface of oxidized PS layer is attractive for bio-applications. The efficiency of the produced PS layers as an entrapping template for specific immobilization of IgG2a antibody via physical absorption process is demonstrated.

Surface topography and ultrastructural architecture of the tegument of adult Carmyerius spatiosus Brandes, 1898.

PubMed

Anuracpreeda, Panat; Phutong, Sumittra; Ngamniyom, Arin; Panyarachun, Busaba; Sobhon, Prasert

2015-03-01

Adult Carmyerius spatiosus or stomach fluke has an elongate, cylindrical-shaped, straight to slightly curved body, with conical anterior end and truncated posterior end. The worm measures about 8.7-11.2mm in body length and 2.3-3.0mm in body width across the mid-section. When observed by SEM, the tegumental surface in all part of the body appears highly corrugated with ridges and furrows, and having no spines. The ventral surface has more complex corrugation than those of the dorsal surface. Both anterior and posterior suckers have thick edges covered with transverse folds and appear spineless. The genital pore is located at the anterior part of the body. There are two types of sensory papillae on the surface: type 1 is bulbous in shape with nipple-like tips; type 2 has a similar shape with short cilia on the tip. The dorsal surface exhibits similar surface features, but papillae appear less numerous and are smaller. When observed by TEM, the tegument is divided into four layers. The first layer includes the ridges and furrows which are covered by a trilaminate membrane underlined by a dense lamina and coated externally with the glycocalyx. The second layer of the tegument is a narrow region of cytoplasm that contains high concentrations of ovoid electron lucent tegumental granules (TG1), and disc-shaped electron dense tegumental granules (TG2) as well as lysosomes. TG1 close to the surface invariably exocytose their content into bottoms of the ridges, while some TG2 are fused and have their membrane joined up with the surface membrane. The third layer is the widest middle area of the tegument which contains numerous and evenly distributed mitochondria. Both TG1 and TG2 granules are present but in much fewer number than in the first and second layers. The fourth layer is the innermost zone that rests on and couples with a thick basal lamina. The cytoplasm in this layer is loosely packed and contains numerous infoldings of the basal plasma membrane with closely associated mitochondria. It also contains fairly large numbers of TG1 and TG2 granules which are produced and transported to the tegument by one type of tegumental cells lying in rows underneath the muscular layers. Copyright © 2014 Elsevier B.V. All rights reserved.

Combining slope stability and groundwater flow models to assess stratovolcano collapse hazard

NASA Astrophysics Data System (ADS)

Ball, J. L.; Taron, J.; Reid, M. E.; Hurwitz, S.; Finn, C.; Bedrosian, P.

2016-12-01

Flank collapses are a well-documented hazard at volcanoes. Elevated pore-fluid pressures and hydrothermal alteration are invoked as potential causes for the instability in many of these collapses. Because pore pressure is linked to water saturation and permeability of volcanic deposits, hydrothermal alteration is often suggested as a means of creating low-permeability zones in volcanoes. Here, we seek to address the question: What alteration geometries will produce elevated pore pressures in a stratovolcano, and what are the effects of these elevated pressures on slope stability? We initially use a finite element groundwater flow model (a modified version of OpenGeoSys) to simulate `generic' stratovolcano geometries that produce elevated pore pressures. We then input these results into the USGS slope-stability code Scoops3D to investigate the effects of alteration and magmatic intrusion on potential flank failure. This approach integrates geophysical data about subsurface alteration, water saturation and rock mechanical properties with data about precipitation and heat influx at Cascade stratovolcanoes. Our simulations show that it is possible to maintain high-elevation water tables in stratovolcanoes given specific ranges of edifice permeability (ideally between 10-15 and 10-16 m2). Low-permeability layers (10-17 m2, representing altered pyroclastic deposits or altered breccias) in the volcanoes can localize saturated regions close to the surface, but they may actually reduce saturation, pore pressures, and water table levels in the core of the volcano. These conditions produce universally lower factor-of-safety (F) values than at an equivalent dry edifice with the same material properties (lower values of F indicate a higher likelihood of collapse). When magmatic intrusions into the base of the cone are added, near-surface pore pressures increase and F decreases exponentially with time ( 7-8% in the first year). However, while near-surface impermeable layers create elevated water tables and pore pressures, they do not necessarily produce the largest or deepest collapses. This suggests that mechanical properties of both the edifice and layers still exert a significant control, and collapse volumes depend on a complex interplay of mechanical factors and layering.

Experiments with a Sphere from which the Boundary Layer Is Removed by Suction

NASA Technical Reports Server (NTRS)

Schrenk, Oskar

1926-01-01

The task of removing the boundary layer by suction consists in producing, in place of the ordinary flow with the formation of vortices, another kind of flow in which the vortices are eliminated by drawing small quantities of fluid from certain points on the surface into the interior of the body. The experiments with a sphere, which constitute the subject of this report, were made early in the present year .

Catalyst surfaces for the chromous/chromic redox couple

NASA Technical Reports Server (NTRS)

Giner, J. D.; Cahill, K. J. (Inventor)

1981-01-01

An electricity producing cell of the reduction-oxidation (REDOX) type divided into two compartments by a membrane is disclosed. A ferrous/ferric couple in a chloride solution serves as a cathode fluid to produce a positive electric potential. A chromic/chromous couple in a chloride solution serves as an anode fluid to produce a negative potential. The electrode is an electrically conductive, inert material plated with copper, silver or gold. A thin layer of lead plates onto the copper, silver or gold layer when the cell is being charged, the lead ions being available from lead chloride which has been added to the anode fluid. If the REDOX cell is then discharged, the lead deplates from the negative electrode and the metal coating on the electrode acts as a catalyst to increase current density.

Description of Mixed-Phase Clouds in Weather Forecast and Climate Models

DTIC Science & Technology

2014-09-30

deficits, leading to freeze-up of both sea ice and the ocean surface. The surface albedo and processes impacting the energy content of the upper ocean...appear key to producing a temporal difference be- tween the freeze-up of the sea - ice surface and adjacent open water. While synoptic conditions, atmos...Leck, 2013: Cloud and boundary layer interactions over the Arctic sea - ice in late summer, Atmos. Chem. Phys. Discuss., 13, 13191-13244, doi

Method for producing high quality oxide films on substrates

DOEpatents

Ruckman, M.W.; Strongin, M.; Gao, Y.L.

1993-11-23

A method is described for providing an oxide film of a material on the surface of a substrate using a reactive deposition of the material onto the substrate surface in the presence of a solid or liquid layer of an oxidizing gas. The oxidizing gas is provided on the substrate surface in an amount sufficient to dissipate the latent heat of condensation occurring during deposition as well as creating a favorable oxidizing environment for the material. 4 figures.

Method for manufacturing lightning strike mitigation composites

NASA Technical Reports Server (NTRS)

Vaidyanathan, K. Ranji (Inventor); Campbell, Jeffrey (Inventor)

2012-01-01

A method for manufacturing a composite material utilizes a tooling material having a desired shape. The surface of the tooling material is coated with a composite film that includes a conductive filler material. A composite composition is introduced into contact with the surface of the tooling material to form a desired shape. The composite composition is processed to produce the composite material, and the composite material has a conductive composite surface layer that includes the conductive filler material.

Undoped and Ni-doped CoO x surface modification of porous BiVO 4 photoelectrodes for water oxidation

DOE PAGES

Liu, Ya; Guo, Youhong; Schelhas, Laura T.; ...

2016-09-29

Surface modification of photoanodes with oxygen evolution reaction (OER) catalysts is an effective approach to enhance water oxidation kinetics, to reduce external bias, and to improve the energy harvesting efficiency of photoelectrochemical (PEC) water oxidation. Here, the surface of porous BiVO 4 photoanodes was modified by the deposition of undoped and Ni-doped CoO x via nitrogen flow assisted electrostatic spray pyrolysis. This newly developed atmospheric pressure deposition technique allows for surface coverage throughout the porous structure with thickness and composition control. PEC testing of modified BiVO 4 photoanodes shows that after deposition of an undoped CoO x surface layer, themore » onset potential shifts negatively by ca. 420 mV and the photocurrent density reaches 2.01 mA cm –2 at 1.23 vs V RHE under AM 1.5G illumination. Modification with Ni-doped CoO x produces even more effective OER catalysis and yields a photocurrent density of 2.62 mA cm –2 at 1.23 V RHE under AM 1.5G illumination. Furthermore, the valence band X-ray photoelectron spectroscopy and synchrotron-based X-ray absorption spectroscopy results show the Ni doping reduces the Fermi level of the CoO x layer; the increased surface band bending produced by this effect is partially responsible for the superior PEC performance.« less

Environmental risks associated with unconventional gas extraction: an Australian perspective

NASA Astrophysics Data System (ADS)

Mallants, Dirk; Bekele, Elise; Schmidt, Wolfgang; Miotlinski, Konrad; Gerke Gerke, Kirill

2015-04-01

Coal seam gas is naturally occurring methane gas (CH4) formed by the degradation of organic material in coal seam layers over geological times, typically over several millions of years. Unlike conventional gas resources, which occur as discrete accumulations in traps formed by folds and other structures in sedimentary layers, coal seam gas is generally trapped in low permeable rock by adsorption of the gas molecules within the rock formation and cannot migrate to a trap and form a conventional gas deposit. Extraction of coal seam gas requires producers to de pressurise the coal measures by abstracting large amounts of groundwater through pumping. For coal measures that have too low permeabilities for gas extraction to be economical, mechanical and chemical techniques are required to increase permeability and thus gas yield. One such technique is hydraulic fracturing (HF). Hydraulic fracturing increases the rate and total amount of gas extracted from coal seam gas reservoirs. The process of hydraulic fracturing involves injecting large volumes of hydraulic fracturing fluids under high pressure into the coal seam layers to open up (i.e. fracture) the gas-containing coal layers, thus facilitating extraction of methane gas through pumping. After a hydraulic fracturing operation has been completed in a coal seam gas well, the fracturing fluid pressure is lowered and a significant proportion of the injected fluid returns to the surface as "flowback" water via coal seam gas wells. Flowback water is fluid that returns to the surface after hydraulic fracturing has occurred but before the well is put into production; whereas produced water is fluid from the coal measure that is pumped to the surface after the well is in production. This paper summarises available literature data from Australian coal seam gas practices on i) spills from hydraulic fracturing-related fluids used during coal seam gas drilling and hydraulic fracturing operations, ii) leaks to soil and shallow groundwater of flowback water and produced water from surface impoundments, iii) risks from well integrity failure, and iv) increased gas in water bores.

Layer by Layer, Nano-particle "Only" Surface Modification of Filtration Membranes

NASA Astrophysics Data System (ADS)

Escobar-Ferrand, Luis

Layer by Layer (LbL) deposition using primarily inorganic silica nanoparticles is employed for the modification of polymeric micro and ultrafiltration (MF/UF) membranes to produce thin film composites (TFC) with potential nanofiltration (NF) and reverse osmosis (RO) capabilities.. A variety of porous substrate membranes with different membrane surface characteristics are employed, but exhibiting in common that wicking of water does not readily occur into the pore structure, including polycarbonate track etched (PCTE), polyethersulfone (PES) and sulfonated PES (SPEES) MF/UF membranes. Both spherical (cationic/anionic) and eccentric elongated (anionic) silica nanoparticles are deposited using conditions similar to those reported by Lee et al. Appropriate selection of the pH's for anionic and cationic particle deposition enables the construction of nanoparticle only layers 100--1200 nm in thickness atop the original membrane substrates. The surface layer thickness varies monotonically with the number of bilayers (anionic/cationic deposition cycles) as expected. The deposition process is optimized to eliminate drying induced cracking and to improve mechanical durability via thickness control and post-deposition hydro-thermal treatment. The hydrodynamic permeability of these TFC membranes is measured to evaluate their performance under typical NF operating conditions using dead-end permeation experiments and their performance compared quantitatively with realistic hydrodynamic models, with favorable results. For track etched polycarbonate MF substrates, surface modification causes a permeability reduction of approximately two orders of magnitude with respect to the bare substrates, to values comparable to those for typical commercial NF membranes. Good quantitative agreement with hydrodynamic models with no adjustable parameters was also established for this case, providing indirect confirmation that the LbL deposited surface layers are largely defect (crack) free. Imaging of our TFC membranes after permeation tests confirmed that no significant mechanical damage resulted, indicating integrity and robustness of the LbL deposited surface layers in typical applications. The selectivity of these novel TFC membranes was also tested using standard "rejection" tests normally used to characterize NF and RO membranes for their capabilities in typical applications, such as water softening or desalination. We report the dextran standards molecular weight "cut-off" (MWCO) using mixed dextrans from 1.5 to 500 KDa in dead-end stir cells, and the percentage of rejection of standard bivalent and monovalent salt solutions using steady cross flow permeation experiments. The results confirm rejection of at least 60% of even the smallest dextrans, an estimated dextran MWCO of 20 KDa, and rejection of 10% and 20% for monovalent (NaCl) and bivalent (MgSO4) salts, respectively, for all the TFC membranes studied, while the unmodified membranes showed no rejection capability at all. The work supports that nanoparticle based LbL surface modification of MF/UF membranes can produce filtration quality media for important water purification applications, such as nanofiltration (NF) softening processes, natural organic matter (NOM) elimination and possibly reverse osmosis (RO) desalination.

Investigation of growth fault bend folding using discrete element modeling: Implications for signatures of active folding above blind thrust faults

NASA Astrophysics Data System (ADS)

Benesh, N. P.; Plesch, A.; Shaw, J. H.; Frost, E. K.

2007-03-01

Using the discrete element modeling method, we examine the two-dimensional nature of fold development above an anticlinal bend in a blind thrust fault. Our models were composed of numerical disks bonded together to form pregrowth strata overlying a fixed fault surface. This pregrowth package was then driven along the fault surface at a fixed velocity using a vertical backstop. Additionally, new particles were generated and deposited onto the pregrowth strata at a fixed rate to produce sequential growth layers. Models with and without mechanical layering were used, and the process of folding was analyzed in comparison with fold geometries predicted by kinematic fault bend folding as well as those observed in natural settings. Our results show that parallel fault bend folding behavior holds to first order in these models; however, a significant decrease in limb dip is noted for younger growth layers in all models. On the basis of comparisons to natural examples, we believe this deviation from kinematic fault bend folding to be a realistic feature of fold development resulting from an axial zone of finite width produced by materials with inherent mechanical strength. These results have important implications for how growth fold structures are used to constrain slip and paleoearthquake ages above blind thrust faults. Most notably, deformation localized about axial surfaces and structural relief across the fold limb seem to be the most robust observations that can readily constrain fault activity and slip. In contrast, fold limb width and shallow growth layer dips appear more variable and dependent on mechanical properties of the strata.

Characterization of AISI 4140 borided steels

NASA Astrophysics Data System (ADS)

Campos-Silva, I.; Ortiz-Domínguez, M.; López-Perrusquia, N.; Meneses-Amador, A.; Escobar-Galindo, R.; Martínez-Trinidad, J.

2010-02-01

The present study characterizes the surface of AISI 4140 steels exposed to the paste-boriding process. The formation of Fe 2B hard coatings was obtained in the temperature range 1123-1273 K with different exposure times, using a 4 mm thick layer of boron carbide paste over the material surface. First, the growth kinetics of boride layers at the surface of AISI 4140 steels was evaluated. Second, the presence and distribution of alloying elements on the Fe 2B phase was measured using the Glow Discharge Optical Emission Spectrometry (GDOES) technique. Further, thermal residual stresses produced on the borided phase were evaluated by X-ray diffraction (XRD) analysis. The fracture toughness of the iron boride layer of the AISI 4140 borided steels was estimated using a Vickers microindentation induced-fracture testing at a constant distance of 25 μm from the surface. The force criterion of fracture toughness was determined from the extent of brittle cracks, both parallel and perpendicular to the surface, originating at the tips of an indenter impression. The fracture toughness values obtained by the Palmqvist crack model are expressed in the form KC( π/2) > KC > KC(0) for the different applied loads and experimental parameters of the boriding process.

Theoretical and Experimental Analysis of an Induction Planar Actuator with Different Secondaries—A Planar Driver Application for Metallic Surface Inspection

PubMed Central

Treviso, Felipe; Silveira, Marilia A.; Flores Filho, Aly F.; Dorrell, David G.

2016-01-01

This paper presents a study on an induction planar actuator concept. The device uses the same principles as a linear induction motor in which the interaction between a travelling magnetic field and a conducting surface produces eddy currents that leads to the generation of a thrust force and can result in movement over a metallic surface. This can benefit the inspection of metallic surfaces based on the driving platform provided by the induction planar actuator. Equations of the magnetic and electric fields are presented and, by means of these equations, the forces involved were calculated. The behaviour of thrust and normal forces was analysed through the equations and by numerical models, and compared with the results obtained by measurements on a device prototype built in the laboratory as part of the study. With relation to the surface under inspection that forms the secondary, three cases were analysed: (1) a double-layered secondary formed by aluminium and ferromagnetic slabs; (2) a single aluminium layer and (3) a single ferromagnetic layer. Theoretical and measured values of thrust and normal forces showed good correlation. PMID:27007377

Physical and technological principles of designing layer-gradient multicomponent surfaces by combining the methods of ion-diffusion saturation and magnetron- and vacuum-arc deposition

NASA Astrophysics Data System (ADS)

Savostikov, V. M.; Potekaev, A. I.; Tabachenko, A. N.

2011-12-01

Using a technological system proposed by the authors, a combined process is developed for formation of stratified-gradient surface layers and multicomponent coatings. It is implemented under the conditions of a combined serial-parallel operation of a hot-cathode gas plasma generator and a duomagnetron with two targets and two electric-arc evaporators. The extended functional potential is ensured by using advanced multi-element and multi-phase cathode targets made of borides, carbides, silicides, and sulfides of metals produced by the SHS-process followed by their immediate compaction. The variations in composition, structure, and physicomechanical properties in the cross-section of the stratified-gradient surface layers and coating is provided by a predetermined alternating replacement of the sputtered cathode targets of the plasma sources, the plasma flow intensity ratios, and variation in the particle energy incident on the substrate, which is determined by the accelerating voltage on the substrate.

Electrophysiologic and morphologic effects of ophthalmic preparations on rabbit cornea epithelium.

PubMed

Burstein, N L; Klyce, S D

1977-10-01

The effects of several components of ophthalmic preparations on isolated rabbit cornea were studied by continuous electrophysiologic monitoring followed by fixation for scanning electron microscopy (SEM). Benzalkonium chloride (0.001 percent), thimerosal (0.0004 percent), and amphotericin B (0.0025 percent) all briefly increased ion transport, then greatly decreased epithelial resistance. Severe disruption of surface cell layers occurred simultaneously with resistance decrease. Silver nitrate (0.00017 percent) stimulated transport with less accompanying morphologic damage. Tetracaine (0.05 percent) disrupted epithelial function and caused exfoliation of several cell layers. Chlorobutanol (0.1 percent) produced a nearly complete loss of the squamous cell layer. Chloramphenicol, epinephrine, and pilocarpine produced minor changes in structure and electrophysiology at full clinical concentration. It was concluded that low concentrations of preservatives in ophthalmic preparations disrupt the barrier and transport properties of the corneal epithelium.

An experimental study of fluctuating pressure loads beneath swept shock/boundary-layer interactions

NASA Technical Reports Server (NTRS)

Settles, Gary S.

1991-01-01

A database is established on the fluctuating pressure loads produced on aerodynamic surfaces beneath 3-D shock wave/boundary layer interactions. Such loads constitute a fundamental problem of critical concern to future supersonic and hypersonic flight vehicles. A turbulent boundary layer on a flat plate is subjected to interactions with swept planar shock waves generated by sharp fins. Fin angles from 5 to 25 deg at freestream Mach numbers between 2.5 and 4 produce a variety of interaction strengths from weak to very strong. Miniature Kulite pressure transducers mounted in the flat plate were used to measure interaction-induced wall pressure fluctuations. These data will be correlated with proposed new optical data on the fluctuations of the interaction structure, especially that of the lambda-shock system and its associated high-speed jet impingement.

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

PubMed

Woo, Yun Chul; Kim, Youngjin; Yao, Minwei; Tijing, Leonard D; Choi, June-Seok; Lee, Sangho; Kim, Seung-Hyun; Shon, Ho Kyong

2018-02-20

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/m 2 h 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.

Orientation of surfactant self-assembled aggregates on graphite

NASA Astrophysics Data System (ADS)

Sammalkorpi, Maria; Hynninen, Antti-Pekka; Panagiotopoulos, Athanassios Z.; Haataja, Mikko

2007-03-01

Micellar aggregates on surfaces can provide a self-healing corrosion protection or lubrication layer. It has been observed experimentally that on a single crystal surface this layer often consists of oriented hemi-cylindrical micelles which are aligned with the underlying crystal lattice (``orientation effect''). A key feature of this self-assembly process is the interplay between detergent--detergent and detergent--surface interactions. Since the dimensions of the detergent molecules and the unit cell of the surface are typically quite different, the origins of this orientation effect remain unclear. Here we address the question and present the results of Molecular Dynamics simulations of sodium dodecyl sulfate (SDS) self-aggregation on graphite. We employ both single-molecule and multi-molecule simulations of SDS to unravel the origins of the orientation effect. We report that the underlying graphite surface is sufficient to impose orientational bias on individual SDS molecules diffusing on the surface. This produces collective effects that give rise to the oriented hemi-micelles.

Silicon on Ceramic Process: Silicon Sheet Growth and Device Development for the Large-area Silicon Sheet and Cell Development Tasks of the Low-cost Solar Array Project

NASA Technical Reports Server (NTRS)

Chapman, P. W.; Zook, J. D.; Heaps, J. D.; Pickering, C.; Grung, B. L.; Koepke, B.; Schuldt, S. B.

1979-01-01

The technical and economic feasibility of producing solar cell quality sheet silicon was investigated. It was hoped this could be done by coating one surface of carbonized ceramic substrates with a thin layer of large-grain polycrystalline silicon from the melt. Work was directed towards the solution of unique cell processing/design problems encountered with the silicon-ceramic (SOC) material due to its intimate contact with the ceramic substrate. Significant progress was demonstrated in the following areas; (1) the continuous coater succeeded in producing small-area coatings exhibiting unidirectional solidification and substatial grain size; (2) dip coater succeeded in producing thick (more than 500 micron) dendritic layers at coating speeds of 0.2-0.3 cm/sec; and (3) a standard for producing total area SOC solar cells using slotted ceramic substrates was developed.

Tensile Behavior of As-Fabricated and Burner-Rig Exposed SiC/SiC Composites with Hi-Nicalon Type-S Fibers

NASA Technical Reports Server (NTRS)

Yun, H. M.; Dicarlo, J. A.; Ogbuji, L. T.; Chen, Y. L.

2002-01-01

Tensile stress-strain curves were measured at room temperature and 1315 C for 2D-woven SiC/BN/SiC ceramic matrix composites (CMC) reinforced by two variations of Hi-Nicalon Type-S SiC fibers. These fibers, which contained a thin continuous carbon-rich layer on their as-produced surface, provided the as-fabricated CMC with good composite behavior and an ultimate strength and strain of -350 MPa and -0.5%, respectively. However, after un-stressed burner-rig exposure at 815 C for -100 hrs, CMC tensile specimens with cut edges and exposed interphases showed a significant decrease in ultimate properties with effectively no composite behavior. Microstructural observations show that the degradation was caused by internal fiber-fiber oxide bonding after removal of the carbon-rich fiber surface layer by the high-velocity combustion gases. On the other hand, SiC/BN/SiC CMC with Sylramic-iBN fibers without carbon-rich surfaces showed higher as-fabricated strength and no loss in strength after the same burner rig exposure. Based on the strong role of the carbon layer in these observations, a process method was developed and demonstrated for achieving better strength retention of Hi-Nicalon Type-S CMC during burner rig exposure. Other general approaches for minimizing this current deficiency with as-produced Type-S fibers are discussed.

Preparation of bioactive titania films on titanium metal via anodic oxidation.

PubMed

Cui, X; Kim, H-M; Kawashita, M; Wang, L; Xiong, T; Kokubo, T; Nakamura, T

2009-01-01

To research the crystal structure and surface morphology of anodic films on titanium metal in different electrolytes under various electrochemical conditions and investigate the effect of the crystal structure of the oxide films on apatite-forming ability in simulated body fluid (SBF). Titanium oxide films were prepared using an anodic oxidation method on the surface of titanium metal in four different electrolytes: sulfuric acid, acetic acid, phosphoric acid and sodium sulfate solutions with different voltages for 1 min at room temperature. Anodic films that consisted of rutile and/or anatase phases with porous structures were formed on titanium metal after anodizing in H(2)SO(4) and Na(2)SO(4) electrolytes, while amorphous titania films were produced after anodizing in CH(3)COOH and H(3)PO(4) electrolytes. Titanium metal with the anatase and/or rutile crystal structure films showed excellent apatite-forming ability and produced a compact apatite layer covering all the surface of titanium after soaking in SBF for 7d, but titanium metal with amorphous titania layers was not able to induce apatite formation. The resultant apatite layer formed on titanium metal in SBF could enhance the bonding strength between living tissue and the implant. Anodic oxidation is believed to be an effective method for preparing bioactive titanium metal as an artificial bone substitute even under load-bearing conditions.

Surface functionalization of carbon nanotubes by direct encapsulation with varying dosages of amphiphilic block copolymers

NASA Astrophysics Data System (ADS)

Yao, Xueping; Li, Jie; Kong, Liang; Wang, Yong

2015-08-01

Encapsulation of carbon nanotubes (CNTs) by amphiphilic block copolymers is an efficient way to stabilize CNTs in solvents. However, the appropriate dosages of copolymers and the assembled structures are difficult to predict and control because of the insufficient understanding on the encapsulation process. We encapsulate multiwalled CNTs with polystyrene-block-poly (4-vinyl pyridine) (PS-b-P4VP) by directly mixing them in acetic acid under sonication. The copolymer forms a lamellar structure along the surface of CNTs with the PS blocks anchoring on the tube wall and the P4VP blocks exposed to the outside. The encapsulated CNTs achieve good dispersibility in polar solvents over long periods. To increase our understanding of the encapsulation process we investigate the assembled structures and stability of copolymer/CNTs mixtures with changing mass ratios. Stable dispersions are obtained at high mass ratios between the copolymer and CNTs, i.e. 2 or 3, with the presence of free spherical micelles. Transmission electron microscopy and thermal gravimetric analysis determine that the threshold for the complete coverage of CNTs by the copolymer occurs at the mass ratio of 1.5. The coated copolymer layer activates the surface of CNTs, enabling further functionalization of CNTs. For instance, atomic layer deposition of TiO2 produces conformal thin layers on the encapsulated CNTs while isolated TiO2 bumps are produced on the pristine, inert CNTs.

Corrosion resistance of titanium ion implanted AZ91 magnesium alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu Chenglong; Xin Yunchang; Tian Xiubo

2007-03-15

Degradable metal alloys constitute a new class of materials for load-bearing biomedical implants. Owing to their good mechanical properties and biocompatibility, magnesium alloys are promising in degradable prosthetic implants. The objective of this study is to improve the corrosion behavior of surgical AZ91 magnesium alloy by titanium ion implantation. The surface characteristics of the ion implanted layer in the magnesium alloys are examined. The authors' results disclose that an intermixed layer is produced and the surface oxidized films are mainly composed of titanium oxide with a lesser amount of magnesium oxide. X-ray photoelectron spectroscopy reveals that the oxide has threemore » layers. The outer layer which is 10 nm thick is mainly composed of MgO and TiO{sub 2} with some Mg(OH){sub 2}. The middle layer that is 50 nm thick comprises predominantly TiO{sub 2} and MgO with minor contributions from MgAl{sub 2}O{sub 4} and TiO. The third layer from the surface is rich in metallic Mg, Ti, Al, and Ti{sub 3}Al. The effects of Ti ion implantation on the corrosion resistance and electrochemical behavior of the magnesium alloys are investigated in simulated body fluids at 37{+-}1 deg. C using electrochemical impedance spectroscopy and open circuit potential techniques. Compared to the unimplanted AZ91 alloy, titanium ion implantation significantly shifts the open circuit potential (OCP) to a more positive potential and improves the corrosion resistance at OCP. This phenomenon can be ascribed to the more compact surface oxide film, enhanced reoxidation on the implanted surface, as well as the increased {beta}-Mg{sub 12}Al{sub 17} phase.« less

Study of ion-irradiated tungsten in deuterium plasma

NASA Astrophysics Data System (ADS)

Khripunov, B. I.; Gureev, V. M.; Koidan, V. S.; Kornienko, S. N.; Latushkin, S. T.; Petrov, V. B.; Ryazanov, A. I.; Semenov, E. V.; Stolyarova, V. G.; Danelyan, L. S.; Kulikauskas, V. S.; Zatekin, V. V.; Unezhev, V. N.

2013-07-01

Experimental study aimed at investigation of neutron induced damage influence on fusion reactor plasma facing materials is reported. Displacement damage was produced in tungsten by high-energy helium and carbon ions at 3-10 MeV. The reached level of displacement damage ranged from several dpa to 600 dpa. The properties of the irradiated tungsten were studied in steady-state deuterium plasma on the LENTA linear divertor simulator. Plasma exposures were made at 250 eV of ion energy to fluence 1021-1022 ion/сm2. Erosion dynamics of the damaged layer and deuterium retention were observed. Surface microstructure modifications and important damage of the 5 μm layer shown. Deuterium retention in helium-damaged tungsten (ERD) showed its complex behavior (increase or decrease) depending on implanted helium quantity and the structure of the surface layer.

Effect of scrape-off-layer current on reconstructed tokamak equilibrium

DOE PAGES

King, J. R.; Kruger, S. E.; Groebner, R. J.; ...

2017-01-13

Methods are described that extend fields from reconstructed equilibria to include scrape-off-layer current through extrapolated parametrized and experimental fits. The extrapolation includes both the effects of the toroidal-field and pressure gradients which produce scrape-off-layer current after recomputation of the Grad-Shafranov solution. To quantify the degree that inclusion of scrape-off-layer current modifies the equilibrium, the χ-squared goodness-of-fit parameter is calculated for cases with and without scrape-off-layer current. The change in χ-squared is found to be minor when scrape-off-layer current is included however flux surfaces are shifted by up to 3 cm. Here the impact on edge modes of these scrape-off-layer modificationsmore » is also found to be small and the importance of these methods to nonlinear computation is discussed.« less

Crystalline ha coating on peek via chemical deposition

NASA Astrophysics Data System (ADS)

Almasi, D.; Izman, S.; Assadian, M.; Ghanbari, M.; Abdul Kadir, M. R.

2014-09-01

Polyether ether ketone (PEEK) has a similar elastic modulus to bone and can be a suitable alternative to metallic implants. However, PEEK is bioinert and does not integrate well with the surrounding tissues. The current commercial method for solving this problem is by coating PEEK substrates with calcium phosphates via plasma spraying. However, this method produces a low bonding strength between the substrate and the coating layer, as well as non-uniform density of the coating. In this study, chemical deposition was used to deposit HA crystalline particles on PEEK substrate without any subsequent crystallisation process therefore producing crystalline treated layer. EDX results confirmed the deposition of HA, and the XRD results confirmed that the treated layer was crystalline HA. FT-IR analysis confirmed the chemical bonding between HA and the substrate. Surface roughness increased from 24.27 nm to 34.08 nm for 3 min immersion time. The water contact angle showed an increase in wettability of the treated sample from 71.6 to 36.4 degrees, which in turn increased its bioactivity. The proposed method is a suitable alternative to other conventional methods as high temperature was not involved in the process which could damage the surface of the substrate.

Optimization and characterization of biomolecule immobilization on silicon substrates using (3-aminopropyl)triethoxysilane (APTES) and glutaraldehyde linker

NASA Astrophysics Data System (ADS)

Gunda, Naga Siva Kumar; Singh, Minashree; Norman, Lana; Kaur, Kamaljit; Mitra, Sushanta K.

2014-06-01

In the present work, we developed and optimized a technique to produce a thin, stable silane layer on silicon substrate in a controlled environment using (3-aminopropyl)triethoxysilane (APTES). The effect of APTES concentration and silanization time on the formation of silane layer is studied using spectroscopic ellipsometry and Fourier transform infrared spectroscopy (FTIR). Biomolecules of interest are immobilized on optimized silane layer formed silicon substrates using glutaraldehyde linker. Surface analytical techniques such as ellipsometry, FTIR, contact angle measurement system, and atomic force microscopy are employed to characterize the bio-chemically modified silicon surfaces at each step of the biomolecule immobilization process. It is observed that a uniform, homogenous and highly dense layer of biomolecules are immobilized with optimized silane layer on the silicon substrate. The developed immobilization method is successfully implemented on different silicon substrates (flat and pillar). Also, different types of biomolecules such as anti-human IgG (rabbit monoclonal to human IgG), Listeria monocytogenes, myoglobin and dengue capture antibodies were successfully immobilized. Further, standard sandwich immunoassay (antibody-antigen-antibody) is employed on respective capture antibody coated silicon substrates. Fluorescence microscopy is used to detect the respective FITC tagged detection antibodies bound to the surface after immunoassay.

Ultrastructure of the embryonic snake skin and putative role of histidine in the differentiation of the shedding complex.

PubMed

Alibardi, Lorenzo

2002-02-01

The morphogenesis and ultrastructure of the epidermis of snake embryos were studied at progressive stages of development through hatching to determine the time and modality of differentiation of the shedding complex. Scales form as symmetric epidermal bumps that become slanted and eventually very overlapped. During the asymmetrization of the bumps, the basal cells of the forming outer surface of the scale become columnar, as in an epidermal placode, and accumulate glycogen. Small dermal condensations are sometimes seen and probably represent primordia of the axial dense dermis of the growing tip of scales. Deep, dense, and superficial loose dermal regions are formed when the epidermis is bilayered (periderm and basal epidermis) and undifferentiated. Glycogen and lipids decrease from basal cells to differentiating suprabasal cells. On the outer scale surface, beneath the peridermis, a layer containing dense granules and sparse 25-30-nm thick coarse filaments is formed. The underlying clear layer does not contain keratohyalin-like granules but has a rich cytoskeleton of intermediate filaments. Small denticles are formed and they interdigitate with the oberhautchen spinulae formed underneath. On the inner scale surface the clear layer contains dense granules, coarse filaments, and does not form denticles with the aspinulated oberhautchen. On the inner side surface the oberhautchen only forms occasional spinulae. The sloughing of the periderm and embryonic epidermis takes place in ovo 5-6 days before hatching. There follow beta-, mesos-, and alpha-layers, not yet mature before hatching. No resting period is present but a new generation is immediately produced so that at 6-10 h posthatching an inner generation and a new shedding complex are forming beneath the outer generation. The first shedding complex differentiates 10-11 days before hatching. In hatchlings 6-10 h old, tritiated histidine is taken up in the epidermis 4 h after injection and is found mainly in the shedding complex, especially in the apposed membranes of the clear layer and oberhautchen cells. This indicates that a histidine-rich protein is produced in preparation for shedding, as previously seen in lizard epidermis. The second shedding (first posthatching) takes place at 7-9 days posthatching. It is suggested that the shedding complex in lepidosaurian reptiles has evolved after the production of a histidine-rich protein and of a beta-keratin layer beneath the former alpha-layer. Copyright 2002 Wiley-Liss, Inc.

Spherical-shell boundaries for two-dimensional compressible convection in a star

NASA Astrophysics Data System (ADS)

Pratt, J.; Baraffe, I.; Goffrey, T.; Geroux, C.; Viallet, M.; Folini, D.; Constantino, T.; Popov, M.; Walder, R.

2016-10-01

Context. Studies of stellar convection typically use a spherical-shell geometry. The radial extent of the shell and the boundary conditions applied are based on the model of the star investigated. We study the impact of different two-dimensional spherical shells on compressible convection. Realistic profiles for density and temperature from an established one-dimensional stellar evolution code are used to produce a model of a large stellar convection zone representative of a young low-mass star, like our sun at 106 years of age. Aims: We analyze how the radial extent of the spherical shell changes the convective dynamics that result in the deep interior of the young sun model, far from the surface. In the near-surface layers, simple small-scale convection develops from the profiles of temperature and density. A central radiative zone below the convection zone provides a lower boundary on the convection zone. The inclusion of either of these physically distinct layers in the spherical shell can potentially affect the characteristics of deep convection. Methods: We perform hydrodynamic implicit large eddy simulations of compressible convection using the MUltidimensional Stellar Implicit Code (MUSIC). Because MUSIC has been designed to use realistic stellar models produced from one-dimensional stellar evolution calculations, MUSIC simulations are capable of seamlessly modeling a whole star. Simulations in two-dimensional spherical shells that have different radial extents are performed over tens or even hundreds of convective turnover times, permitting the collection of well-converged statistics. Results: To measure the impact of the spherical-shell geometry and our treatment of boundaries, we evaluate basic statistics of the convective turnover time, the convective velocity, and the overshooting layer. These quantities are selected for their relevance to one-dimensional stellar evolution calculations, so that our results are focused toward studies exploiting the so-called 321D link. We find that the inclusion in the spherical shell of the boundary between the radiative and convection zones decreases the amplitude of convective velocities in the convection zone. The inclusion of near-surface layers in the spherical shell can increase the amplitude of convective velocities, although the radial structure of the velocity profile established by deep convection is unchanged. The impact of including the near-surface layers depends on the speed and structure of small-scale convection in the near-surface layers. Larger convective velocities in the convection zone result in a commensurate increase in the overshooting layer width and a decrease in the convective turnover time. These results provide support for non-local aspects of convection.

Investigation of passive shock wave-boundary layer control for transonic airfoil drag reduction

NASA Technical Reports Server (NTRS)

Nagamatsu, H. T.; Brower, W. B., Jr.; Bahi, L.; Ross, J.

1982-01-01

The passive drag control concept, consisting of a porous surface with a cavity beneath it, was investigated with a 12-percent-thick circular arc and a 14-percent-thick supercritical airfoil mounted on the test section bottom wall. The porous surface was positioned in the shock wave/boundary layer interaction region. The flow circulating through the porous surface, from the downstream to the upstream of the terminating shock wave location, produced a lambda shock wave system and a pressure decrease in the downstream region minimizing the flow separation. The wake impact pressure data show an appreciably drag reduction with the porous surface at transonic speeds. To determine the optimum size of porosity and cavity, tunnel tests were conducted with different airfoil porosities, cavities and flow Mach numbers. A higher drag reduction was obtained by the 2.5 percent porosity and the 1/4-inch deep cavity.

Dead layer on silicon p-i-n diode charged-particle detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wall, B. L.; Amsbaugh, John F.; Beglarian, A.

Abstract Semiconductor detectors in general have a dead layer at their surfaces that is either a result of natural or induced passivation, or is formed during the process of making a contact. Charged particles passing through this region produce ionization that is incompletely collected and recorded, which leads to departures from the ideal in both energy deposition and resolution. The silicon p-i-n diode used in the KATRIN neutrinomass experiment has such a dead layer. We have constructed a detailed Monte Carlo model for the passage of electrons from vacuum into a silicon detector, and compared the measured energy spectra tomore » the predicted ones for a range of energies from 12 to 20 keV. The comparison provides experimental evidence that a substantial fraction of the ionization produced in the "dead" layer evidently escapes by discussion, with 46% being collected in the depletion zone and the balance being neutralized at the contact or by bulk recombination. The most elementary model of a thinner dead layer from which no charge is collected is strongly disfavored.« less

Electron Tunneling in Junctions Doped with Semiconductors and Metals.

NASA Astrophysics Data System (ADS)

Bell, Lloyd Douglas, II

In this study, tunnel junctions incorporating thin layers of semiconductors and metals have been analyzed. Inelastic electron tunneling spectroscopy (IETS) was employed to yield high-resolution vibrational spectra of surface species deposited at the oxide-M_2 interface of M_1-M_1O _{rm x}-M _2 tunneling samples. Analysis was also performed on the elastic component of the tunneling current, yielding information on the tunnel barrier shape. The samples in this research exhibit a wide range of behavior. The IETS for Si, SiO_2, and Ge doped samples show direct evidence of SiH _{rm x} and GeH_ {rm x} formation. The particular species formed is shown to depend on the form of the evaporated dopant. Samples were also made with organic dopants deposited over the evaporated dopants. Many such samples show marked effects of the evaporated dopants on the inelastic peak intensities of the organic dopants. These alterations are correlated with the changed reactivity of the oxide surface coupled with a change in the OH dipole layer density on the oxide. Thicker organic dopant layers cause large changes in the elastic tunneling barrier due to OH layer alterations or the low barrier attributes of the evaporated dopant. In the cases of the thicker layers an extra current-carrying mechanism is shown to be contributing. Electron ejection from charge traps is proposed as an explanation for this extra current. The trend of barrier shape with dopant thickness is examined. Many of these dopants also produce a voltage-induced shift in the barrier shape which is stable at low temperature but relaxes at high temperature. This effect is similar to that produced by certain organic dopants and is explained by metastable bond formation between the surface OH and dopant. Other dopants, such as Al, Mg, and Fe, produce different effects. These dopants cause large I-V nonlinearity at low voltages. This nonlinearity is modeled as a giant zero-bias anomaly (ZBA) and fits are presented which show good agreement with theory. For some samples, poor fits result due to additional nonlinearity at higher voltages. This is explained in terms of a barrier lowering due to disruption of the OH layer or the small bandgap of the dopant.

Double-Layer Gadolinium Zirconate/Yttria-Stabilized Zirconia Thermal Barrier Coatings Deposited by the Solution Precursor Plasma Spray Process

NASA Astrophysics Data System (ADS)

Jiang, Chen; Jordan, Eric H.; Harris, Alan B.; Gell, Maurice; Roth, Jeffrey

2015-08-01

Advanced thermal barrier coatings (TBCs) with lower thermal conductivity, increased resistance to calcium-magnesium-aluminosilicate (CMAS), and improved high-temperature capability, compared to traditional yttria-stabilized zirconia (YSZ) TBCs, are essential to higher efficiency in next generation gas turbine engines. Double-layer rare-earth zirconate/YSZ TBCs are a promising solution. From a processing perspective, solution precursor plasma spray (SPPS) process with its unique and beneficial microstructural features can be an effective approach to obtaining the double-layer microstructure. Previously durable low-thermal-conductivity YSZ TBCs with optimized layered porosity, called the inter-pass boundaries (IPBs) were produced using the SPPS process. In this study, an SPPS gadolinium zirconate (GZO) protective surface layer was successfully added. These SPPS double-layer TBCs not only retained good cyclic durability and low thermal conductivity, but also demonstrated favorable phase stability and increased surface temperature capabilities. The CMAS resistance was evaluated with both accumulative and single applications of simulated CMAS in isothermal furnaces. The double-layer YSZ/GZO exhibited dramatic improvement in the single application, but not in the continuous one. In addition, to explore their potential application in integrated gasification combined cycle environments, double-layer TBCs were tested under high-temperature humidity and encouraging performance was recorded.

NMR of thin layers using a meanderline surface coil

DOEpatents

Cowgill, Donald F.

2001-01-01

A miniature meanderline sensor coil which extends the capabilities of nuclear magnetic resonance (NMR) to provide analysis of thin planar samples and surface layer geometries. The sensor coil allows standard NMR techniques to be used to examine thin planar (or curved) layers, extending NMRs utility to many problems of modern interest. This technique can be used to examine contact layers, non-destructively depth profile into films, or image multiple layers in a 3-dimensional sense. It lends itself to high resolution NMR techniques of magic angle spinning and thus can be used to examine the bonding and electronic structure in layered materials or to observe the chemistry associated with aging coatings. Coupling this sensor coil technology with an arrangement of small magnets will produce a penetrator probe for remote in-situ chemical analysis of groundwater or contaminant sediments. Alternatively, the sensor coil can be further miniaturized to provide sub-micron depth resolution within thin films or to orthoscopically examine living tissue. This thin-layer NMR technique using a stationary meanderline coil in a series-resonant circuit has been demonstrated and it has been determined that the flat meanderline geometry has about he same detection sensitivity as a solenoidal coil, but is specifically tailored to examine planar material layers, while avoiding signals from the bulk.

Breakthrough to Non-Vacuum Deposition of Single-Crystal, Ultra-Thin, Homogeneous Nanoparticle Layers: A Better Alternative to Chemical Bath Deposition and Atomic Layer Deposition

PubMed Central

Liao, Yu-Kuang; Liu, Yung-Tsung; Hsieh, Dan-Hua; Shen, Tien-Lin; Hsieh, Ming-Yang; Tzou, An-Jye; Chen, Shih-Chen; Tsai, Yu-Lin; Lin, Wei-Sheng; Chan, Sheng-Wen; Shen, Yen-Ping; Cheng, Shun-Jen; Chen, Chyong-Hua; Wu, Kaung-Hsiung; Chen, Hao-Ming; Kuo, Shou-Yi; Charlton, Martin D. B.; Hsieh, Tung-Po; Kuo, Hao-Chung

2017-01-01

Most thin-film techniques require a multiple vacuum process, and cannot produce high-coverage continuous thin films with the thickness of a few nanometers on rough surfaces. We present a new ”paradigm shift” non-vacuum process to deposit high-quality, ultra-thin, single-crystal layers of coalesced sulfide nanoparticles (NPs) with controllable thickness down to a few nanometers, based on thermal decomposition. This provides high-coverage, homogeneous thickness, and large-area deposition over a rough surface, with little material loss or liquid chemical waste, and deposition rates of 10 nm/min. This technique can potentially replace conventional thin-film deposition methods, such as atomic layer deposition (ALD) and chemical bath deposition (CBD) as used by the Cu(In,Ga)Se2 (CIGS) thin-film solar cell industry for decades. We demonstrate 32% improvement of CIGS thin-film solar cell efficiency in comparison to reference devices prepared by conventional CBD deposition method by depositing the ZnS NPs buffer layer using the new process. The new ZnS NPs layer allows reduction of an intrinsic ZnO layer, which can lead to severe shunt leakage in case of a CBD buffer layer. This leads to a 65% relative efficiency increase. PMID:28383488

Local epitaxial growth of ZrO2 on Ge (100) substrates by atomic layer epitaxy

NASA Astrophysics Data System (ADS)

Kim, Hyoungsub; Chui, Chi On; Saraswat, Krishna C.; McIntyre, Paul C.

2003-09-01

High-k dielectric deposition processes for gate dielectric preparation on Si surfaces usually result in the unavoidable and uncontrolled formation of a thin interfacial oxide layer. Atomic layer deposition of ˜55-Å ZrO2 film on a Ge (100) substrate using ZrCl4 and H2O at 300 °C was found to produce local epitaxial growth [(001) Ge//(001) ZrO2 and [100] Ge//[100] ZrO2] without a distinct interfacial layer, unlike the situation observed when ZrO2 is deposited using the same method on Si. Relatively large lattice mismatch (˜10%) between ZrO2 and Ge produced a high areal density of interfacial misfit dislocations. Large hysteresis (>200 mV) and high frequency dispersion were observed in capacitance-voltage measurements due to the high density of interface states. However, a low leakage current density, comparable to values obtained on Si substrates, was observed with the same capacitance density regardless of the high defect density.

Etching of moldavities under natural conditions

NASA Technical Reports Server (NTRS)

Knobloch, V.; Knoblochova, Z.; Urbanec, Z.

1983-01-01

The hypothesis that a part of the lechatellierites which originated by etching from a basic moldavite mass became broken off after deposition of moldavite in the sedimentation layer is advanced. Those found close to the original moldavite were measured for statistical averaging of length. The average length of lechatelierite fibers per cubic mm of moldavite mass volume was determined by measurement under a microscope in toluene. The data were used to calculate the depth of the moldavite layer that had to be etched to produce the corresponding amount of lechatelierite fragments. The calculations from five "fields" of moldavite surface, where layers of fixed lechatelierite fragments were preserved, produced values of 2.0, 3.1, 3.5, 3.9 and 4.5. Due to inadvertent loss of some fragments the determined values are somewhat lower than those found in references. The difference may be explained by the fact that the depth of the layer is only that caused by etching after moldavite deposition.

Modified laser-annealing process for improving the quality of electrical P-N junctions and devices

DOEpatents

Wood, Richard F.; Young, Rosa T.

1984-01-01

The invention is a process for producing improved electrical-junction devices. The invention is applicable, for example, to a process in which a light-sensitive electrical-junction device is produced by (1) providing a body of crystalline semiconductor material having a doped surface layer, (2) irradiating the layer with at least one laser pulse to effect melting of the layer, (3) permitting recrystallization of the melted layer, and (4) providing the resulting body with electrical contacts. In accordance with the invention, the fill-factor and open-circuit-voltage parameters of the device are increased by conducting the irradiation with the substrate as a whole at a selected elevated temperature, the temperature being selected to effect a reduction in the rate of the recrystallization but insufficient to effect substantial migration of impurities within the body. In the case of doped silicon substrates, the substrate may be heated to a temperature in the range of from about 200.degree. C. to 500.degree. C.

Mechanical properties of Cr-Cu coatings produced by electroplating

NASA Astrophysics Data System (ADS)

Riyadi, Tri Widodo Besar; Sarjito, Masyrukan, Riswan, Ricky Ary

2017-06-01

Hard chromium coatings has long been considered as the most used electrodeposited coating in several industrial applications such as in petrochemistry, oil and gas industries. When hard coatings used in fastener components, the sliding contact during fastening operation produces high tensile stresses on the surface which can generate microcracks. For component used in high oxidation and corrosion environment, deep cracks cannot be tolerated. In this work, a laminated structure of Cr-Cu coating was prepared using electroplating on carbon steel substrates. Two baths of chrome and copper electrolyte solutions were prepared to deposit Cr as the first layer and Cu as the second layer. The effect of current voltages on the thickness, hardness and specific wear rate of the Cu layer was investigated. The results show that an increase of the current voltages increased the thickness and hardness of the Cu layer, but reduced the specific wear rate. This study showed that the use of Cu can be a potential candidate as a laminated structure Cr-Cu for chromium plating.

Deformation sensor based on polymer-supported discontinuous graphene multi-layer coatings

NASA Astrophysics Data System (ADS)

Carotenuto, G.; Schiavo, L.; Romeo, V.; Nicolais, L.

2014-05-01

Graphene can be conveniently used in the modification of polymer surfaces. Graphene macromolecules are perfectly transparent to the visible light and electrically conductive, consequently these two properties can be simultaneously provided to polymeric substrates by surface coating with thin graphene layers. In addition, such coating process provides the substrates of: water-repellence, higher surface hardness, low-friction, self-lubrication, gas-barrier properties, and many other functionalities. Polyolefins have a non-polar nature and therefore graphene strongly sticks on their surface. Nano-crystalline graphite can be used as graphene precursor in some chemical processes (e.g., graphite oxide synthesis by the Hummer method), in addition it can be directly applied to the surface of a polyolefin substrate (e.g., polyethylene) to cover it by a thin graphene multilayer. In particular, the nano-crystalline graphite perfectly exfoliate under the application of a combination of shear and friction forces and the produced graphene single-layers perfectly spread and adhere on the polyethylene substrate surface. Such polymeric materials can be used as ITO (indium-tin oxide) substitute and in the fabrication of different electronic devices. Here the fabrication of transparent resistive deformation sensors based on low-density polyethylene films coated by graphene multilayers is described. Such devices are very sensible and show a high reversible and reproducible behavior.

Selective formation of porous silicon

NASA Technical Reports Server (NTRS)

Fathauer, Robert W. (Inventor); Jones, Eric W. (Inventor)

1993-01-01

A pattern of porous silicon is produced in the surface of a silicon substrate by forming a pattern of crystal defects in said surface, preferably by applying an ion milling beam through openings in a photoresist layer to the surface, and then exposing said surface to a stain etchant, such as HF:HNO3:H2O. The defected crystal will preferentially etch to form a pattern of porous silicon. When the amorphous content of the porous silicon exceeds 70 percent, the porous silicon pattern emits visible light at room temperature.

Silicon Alignment Pins: An Easy Way to Realize a Wafer-To-Wafer Alignment

NASA Technical Reports Server (NTRS)

Peralta, Alejandro (Inventor); Gill, John J. (Inventor); Toda, Risaku (Inventor); Lin, Robert H. (Inventor); Jung-Kubiak, Cecile (Inventor); Reck, Theodore (Inventor); Thomas, Bertrand (Inventor); Siles, Jose V. (Inventor); Lee, Choonsup (Inventor); Chattopadhyay, Goutam (Inventor)

2016-01-01

A silicon alignment pin is used to align successive layers of components made in semiconductor chips and/or metallic components to make easier the assembly of devices having a layered structure. The pin is made as a compressible structure which can be squeezed to reduce its outer diameter, have one end fit into a corresponding alignment pocket or cavity defined in a layer of material to be assembled into a layered structure, and then allowed to expand to produce an interference fit with the cavity. The other end can then be inserted into a corresponding cavity defined in a surface of a second layer of material that mates with the first layer. The two layers are in registry when the pin is mated to both. Multiple layers can be assembled to create a multilayer structure. Examples of such devices are presented.

Characterization of Ag-porous silicon nanostructured layer formed by an electrochemical etching of p-type silicon surface for bio-application

NASA Astrophysics Data System (ADS)

Naddaf, M.; Al-Mariri, A.; Haj-Mhmoud, N.

2017-06-01

Nanostructured layers composed of silver-porous silicon (Ag-PS) have been formed by an electrochemical etching of p-type (1 1 1) silicon substrate in a AgNO3:HF:C2H5OH solution at different etching times (10 min-30 min). Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) results reveal that the produced layers consist of Ag dendrites and a silicon-rich porous structure. The nanostructuring nature of the layer has been confirmed by spatial micro-Raman scattering and x-ray diffraction techniques. The Ag dendrites exhibit a surface-enhanced Raman scattering (SERS) spectrum, while the porous structure shows a typical PS Raman spectrum. Upon increasing the etching time, the average size of silicon nanocrystallite in the PS network decreases, while the average size of Ag nanocrystals is slightly affected. In addition, the immobilization of prokaryote Salmonella typhimurium DNA via physical adsorption onto the Ag-PS layer has been performed to demonstrate its efficiency as a platform for detection of biological molecules using SERS.

Structure and optical properties of 2D layered MoS2 crystals implemented with novel friction induced crystal growth

NASA Astrophysics Data System (ADS)

Tanabe, Tadao; Ito, Takafumi; Oyama, Yutaka

2018-03-01

We used X-ray diffraction, and Raman and photoluminescence (PL) spectroscopies to examine the structure and optical properties of molybdenum disulfide (MoS2) crystals grown by friction at the interface between two materials. MoS2 is produced chemically from molybdenum dithiocarbamates (MoDTC) in synthetic oil under sliding friction conditions. The X-ray diffraction (XRD) patterns indicate that the structure of the MoS2 is layered with the c-axis perpendicular to the surface. The MoS2 layer was formed on stainless steel and germanium by friction at the interface between these materials and high carbon chromium bearing steel. The number of layers is estimated to be N (N > 6) from the distance between the Raman frequencies of the E12g and A1g modes. For MoS2 grown on stainless steel, exciton peak is observed in the PL spectrum at room temperature. These results show that this friction induced crystal growth method is viable for synthesizing atomic layers of MoS2 at solid surfaces.

Volumetric Visualization of Human Skin

NASA Astrophysics Data System (ADS)

Kawai, Toshiyuki; Kurioka, Yoshihiro

We propose a modeling and rendering technique of human skin, which can provide realistic color, gloss and translucency for various applications in computer graphics. Our method is based on volumetric representation of the structure inside of the skin. Our model consists of the stratum corneum and three layers of pigments. The stratum corneum has also layered structure in which the incident light is reflected, refracted and diffused. Each layer of pigment has carotene, melanin or hemoglobin. The density distributions of pigments which define the color of each layer can be supplied as one of the voxel values. Surface normals of upper-side voxels are fluctuated to produce bumps and lines on the skin. We apply ray tracing approach to this model to obtain the rendered image. Multiple scattering in the stratum corneum, reflective and absorptive spectrum of pigments are considered. We also consider Fresnel term to calculate the specular component for glossy surface of skin. Some examples of rendered images are shown, which can successfully visualize a human skin.

Comparison of tungsten nano-tendrils grown in Alcator C-Mod and linear plasma devices

NASA Astrophysics Data System (ADS)

Wright, G. M.; Brunner, D.; Baldwin, M. J.; Bystrov, K.; Doerner, R. P.; Labombard, B.; Lipschultz, B.; De Temmerman, G.; Terry, J. L.; Whyte, D. G.; Woller, K. B.

2013-07-01

Growth of tungsten nano-tendrils ("fuzz") has been observed for the first time in the divertor region of a high-power density tokamak experiment. After 14 consecutive helium L-mode discharges in Alcator C-Mod, the tip of a tungsten Langmuir probe at the outer strike point was fully covered with a layer of nano-tendrils. The depth of the W fuzz layer (600 ± 150 nm) is consistent with an empirical growth formula from the PISCES experiment. Re-creating the C-Mod exposures as closely as possible in Pilot-PSI experiment can produce nearly-identical nano-tendril morphology and layer thickness at surface temperatures that agree with uncertainties with the C-Mod W probe temperature data. Helium concentrations in W fuzz layers are measured at 1-4 at.%, which is lower than expected for the observed sub-surface voids to be filled with several GPa of helium pressure. This possibly indicates that the void formation is not pressure driven.

The Diamond Window with Boron-Doped Layers for the Output of Microwave Radiation at High Peak and Average Power Levels

NASA Astrophysics Data System (ADS)

Ivanov, O. A.; Kuzikov, S. V.; Vikharev, A. A.; Vikharev, A. L.; Lobaev, M. A.

2017-10-01

We propose a novel design of the barrier window for the output of microwave radiation at high peak and average power levels. A window based on a plate of polycrystalline CVD diamond with thin (nanometer-thick) boron-doped layers with increased conductivity is considered. Such a window, which retains the low radiation loss due to the small total thickness of the conductive layers and the high thermal conductivity inherent in diamond, prevents accumulation of a static charge on its surface, on the one hand, and allows one to produce a static electric field on the surface of the doped layer, which impedes the development of a multipactor discharge, on the other hand. In this case, a high level of the power of the transmitted radiation and a large passband width are ensured by choosing the configuration of the field in the form of a traveling wave inside the window.

Natural Underwater Adhesives

PubMed Central

Stewart, Russell J.; Ransom, Todd C.; Hlady, Vladimir

2011-01-01

The general topic of this review is protein-based underwater adhesives produced by aquatic organisms. The focus is on mechanisms of interfacial adhesion to native surfaces and controlled underwater solidification of natural water-borne adhesives. Four genera that exemplify the broad range of function, general mechanistic features, and unique adaptations are discussed in detail: blue mussels, acorn barnacles, sandcastle worms, and freshwater caddisfly larva. Aquatic surfaces in nature are charged and in equilibrium with their environment, populated by an electrical double layer of ions as well as adsorbed natural polyelectrolytes and microbial biofilms. Surface adsorption of underwater bioadhesives likely occurs by exchange of surface bound ligands by amino acid sidechains, driven primarily by relative affinities and effective concentrations of polymeric functional groups. Most aquatic organisms exploit modified amino acid sidechains, in particular phosphorylated serines and hydroxylated tyrosines (dopa), with high-surface affinity that form coordinative surface complexes. After delivery to the surfaces as a fluid, permanent natural adhesives solidify to bear sustained loads. Mussel plaques are assembled in a manner superficially reminiscent of in vitro layer-by-layer strategies, with sequentially delivered layers associated through Fe(dopa)3 coordination bonds. The adhesives of sandcastle worms, caddisfly larva, and barnacles may be delivered in a form somewhat similar to in vitro complex coacervation. Marine adhesives are secreted, or excreted, into seawater that has a significantly higher pH and ionic strength than the internal environment. Empirical evidence suggests these environment triggers could provide minimalistic, fail-safe timing mechanisms to prevent premature solidification (insolubilization) of the glue within the secretory system, yet allow rapid solidification after secretion. Underwater bioadhesives are further strengthened by secondary covalent curing. PMID:21643511

Fabrication of luminescent porous silicon with stain etches and evidence that luminescence originates in amorphous layers

NASA Technical Reports Server (NTRS)

Fathauer, R. W.; George, T.; Ksendzov, A.; Lin, T. L.; Pike, W. T.; Vasquez, R. P.; Wu, Z.-C.

1992-01-01

Simple immersion of Si in stain etches of HF:HNO3:H2O or NaNO2 in aqueous HF was used to produce films exhibiting luminescence in the visible similar to that of anodically-etched porous Si. All of the luminescent samples consist of amorphous porous Si in at least the near surface region. No evidence was found for small crystalline regions within these amorphous layers.

Simulations of Quantum Dot Growth on Semiconductor Surfaces: Morphological Design of Sensor Concepts

DTIC Science & Technology

2008-12-01

size equalization can be clearly illustrated during the growth process. In this work we develop a fast multiscale 3D kinetic Monte Carlo ( KMC ) QD...model will provide an attractive means for producing predictably ordered nanostructures. MODEL DESCRIPTION The 3D layer-by-layer KMC growth model...Voter, 2001) and KMC simulation experience (Pan et al., 2004; Pan et al., 2006; Meixner et al, 2003) in 2D, we therefore propose the following simple

Space charge induced surface stresses: implications in ceria and other ionic solids.

PubMed

Sheldon, Brian W; Shenoy, Vivek B

2011-05-27

Volume changes associated with point defects in space charge layers can produce strains that substantially alter thermodynamic equilibrium near surfaces in ionic solids. For example, near-surface compressive stresses exceeding -10 GPa are predicted for ceria. The magnitude of this effect is consistent with anomalous lattice parameter increases that occur in ceria nanoparticles. These stresses should significantly alter defect concentrations and key transport properties in a wide range of materials (e.g., ceria electrolytes in fuel cells). © 2011 American Physical Society

On the theory of compliant wall drag reduction in turbulent boundary layers

NASA Technical Reports Server (NTRS)

Ash, R. L.

1974-01-01

A theoretical model has been developed which can explain how the motion of a compliant wall reduces turbulent skin friction drag. Available experimental evidence at low speeds has been used to infer that a compliant surface selectively removes energy from the upper frequency range of the energy containing eddies and through resulting surface motions can produce locally negative Reynolds stresses at the wall. The theory establishes a preliminary amplitude and frequency criterion as the basis for designing effective drag reducing compliant surfaces.

Three dimensional metal/N-doped nanoplate carbon catalysts for oxygen reduction, the reason for using a layered nanoreactor.

PubMed

Yeganeh Ghotbi, Mohammad; Javanmard, Arash; Soleimani, Hassan

2018-02-21

A layered nanoreactor (zinc hydroxide gallate/nitrate nanohybrid) has been designed as a nano-vessel to confine the gallate/nitrate reaction inside zinc hydroxide layers for production of metal/nitrogen-doped carbon catalysts. Metals (Fe 2+ , Co 2+ and Ni 2+ ) doped and bare zinc hydroxide nitrates (ZHN) were synthesized as the α-phase hydroxide hosts. By an incomplete ion-exchange process, nitrate anions between the layers of the hosts were then partially replaced by the gallate anions to produce the layered nanoreactors. Under heat-treatment, the reaction between the remaining un-exchanged nitrate anions and the organic moiety inside the basal spacing of each nanohybrid plate resulted in obtaining highly porous 3D metal/nitrogen-doped carbon nanosheets. These catalysts were then used as extremely efficient electrocatalysts for catalyzing oxygen reduction reaction (ORR). This study is intended to show the way to get maximum electrocatalytic activity of the metal/N-doped carbon catalysts toward the ORR. This exceptionally high ORR performance originates from the increased available surface, the best pore size range and the uniform distribution of the active sites in the produced catalysts, all provided by the use of new idea of the layered nanoreactor.

Silicon-ion-implanted PMMA with nanostructured ultrathin layers for plastic electronics

NASA Astrophysics Data System (ADS)

Hadjichristov, G. B.; Ivanov, Tz E.; Marinov, Y. G.

2014-12-01

Being of interest for plastic electronics, ion-beam produced nanostructure, namely silicon ion (Si+) implanted polymethyl-methacrylate (PMMA) with ultrathin nanostructured dielectric (NSD) top layer and nanocomposite (NC) buried layer, is examined by electric measurements. In the proposed field-effect organic nanomaterial structure produced within the PMMA network by ion implantation with low energy (50 keV) Si+ at the fluence of 3.2 × 1016 cm-2 the gate NSD is ion-nanotracks-modified low-conductive surface layer, and the channel NC consists of carbon nanoclusters. In the studied ion-modified PMMA field-effect configuration, the gate NSD and the buried NC are formed as planar layers both with a thickness of about 80 nm. The NC channel of nano-clustered amorphous carbon (that is an organic semiconductor) provides a huge increase in the electrical conduction of the material in the subsurface region, but also modulates the electric field distribution in the drift region. The field effect via the gate NSD is analyzed. The most important performance parameters, such as the charge carrier field-effect mobility and amplification of this particular type of PMMA- based transconductance device with NC n-type channel and gate NSD top layer, are determined.

High Tech Art: Chameleon Glass

NASA Technical Reports Server (NTRS)

1993-01-01

Dichroic Glass is a technology wherein extremely thin films of metal are vacuum deposited on a glass surface. The coated glass shields spacecraft instruments from cosmic radiation and protects human vision from unfiltered sunlight in space. Because the coating process allows some wavelengths of light and color to reflect and others to pass through, a chameleon effect is produced. Murray Schwartz, a former aerospace engineer, has based his business KROMA on this NASA optical technology. He produces dichroic stained glass windows, mobiles and jewelry. The technique involves deposition of super thin layers of metal oxides applied one layer at a time in a specific order and thickness for the desired effect. His product line is unique and has been very successful.

Anti-reflection coatings applied by acid leaching process

NASA Technical Reports Server (NTRS)

Pastirik, E.

1980-01-01

The Magicote C process developed by S.M. Thompsen was evaluated for use in applying an antireflective coating to the cover plates of solar panels. The process uses a fluosilicic acid solution supersaturated with silica at elevated temperature to selectively attack the surface of soda-lime glass cover plates and alter the physical and chemical composition of a thin layer of glass. The altered glass layer constitutes an antireflective coating. The process produces coatings of excellent optical quality which possess outstanding resistance to soiling and staining. The coatings produced are not resistant to mechanical abrasion and are attacked to some extent by glass cleansers. Control of the filming process was found to be difficult.

Effect of Plasma Nitriding and Nitrocarburizing on HVOF-Sprayed Stainless Steel Coatings

NASA Astrophysics Data System (ADS)

Park, Gayoung; Bae, Gyuyeol; Moon, Kyungil; Lee, Changhee

2013-12-01

In this work, the effects of plasma nitriding (PN) and nitrocarburizing on HVOF-sprayed stainless steel nitride layers were investigated. 316 (austenitic), 17-4PH (precipitation hardening), and 410 (martensitic) stainless steels were plasma-nitrided and nitrocarburized using a N2 + H2 gas mixture and the gas mixture containing C2H2, respectively, at 550 °C. The results showed that the PN and nitrocarburizing produced a relatively thick nitrided layer consisting of a compound layer and an adjacent nitrogen diffusion layer depending on the crystal structures of the HVOF-sprayed stainless steel coatings. Also, the diffusion depth of nitrogen increased when a small amount of C2H2 (plasma nitrocarburizing process) was added. The PN and nitrocarburizing resulted in not only an increase of the surface hardness, but also improvement of the load bearing capacity of the HVOF-sprayed stainless steel coatings because of the formation of CrN, Fe3N, and Fe4N phases. Also, the plasma-nitrocarburized HVOF-sprayed 410 stainless steel had a superior surface microhardness and load bearing capacity due to the formation of Cr23C6 on the surface.

Conversion coatings prepared or treated with calcium hydroxide solutions

NASA Technical Reports Server (NTRS)

Maxey, Jason (Inventor); Nelson, Carl (Inventor); Eylem, Cahit (Inventor); Minevski, Zoran (Inventor); Clarke, Eric (Inventor)

2002-01-01

A conversion coating process that forms a stable and corrosion-resistant oxide layer on metal or metal oxide substrates or layers. Particularly, the conversion coating process involves contacting the metal or metal oxide substrate or layer with the aqueous calcium hydroxide solutions in order to convert the surface of the substrate to a stable metal oxide layer or coating. According to the present invention, the calcium hydroxide solution is prepared by removing carbon dioxide from water or an aqueous solution before introducing the calcium hydroxide. In this manner, formation of calcium carbonate particles is avoided and the porosity of the conversion coating produced by the calcium hydroxide solution is reduced to below about 1%.

Fully integrated and encapsulated micro-fabricated vacuum diode and method of manufacturing same

DOEpatents

Resnick, Paul J.; Langlois, Eric

2015-12-01

Disclosed is an encapsulated micro-diode and a method for producing same. The method comprises forming a plurality columns in the substrate with a respective tip disposed at a first end of the column, the tip defining a cathode of the diode; disposing a sacrificial oxide layer on the substrate, plurality of columns and respective tips; forming respective trenches in the sacrificial oxide layer around the columns; forming an opening in the sacrificial oxide layer to expose a portion of the tips; depositing a conductive material in of the opening and on a surface of the substrate to form an anode of the diode; and removing the sacrificial oxide layer.

Method of manufacturing a fully integrated and encapsulated micro-fabricated vacuum diode

DOEpatents

Resnick, Paul J.; Langlois, Eric

2014-08-26

Disclosed is an encapsulated micro-diode and a method for producing same. The method comprises forming a plurality columns in the substrate with a respective tip disposed at a first end of the column, the tip defining a cathode of the diode; disposing a sacrificial oxide layer on the substrate, plurality of columns and respective tips; forming respective trenches in the sacrificial oxide layer around the columns; forming an opening in the sacrificial oxide layer to expose a portion of the tips; depositing a conductive material in of the opening and on a surface of the substrate to form an anode of the diode; and removing the sacrificial oxide layer.

Rain Rate from IMERG as a Predictor for Salinity Stratification in the Upper Meter of the Ocean during SPURS-2 Rain Events

NASA Astrophysics Data System (ADS)

Thompson, E. J.; Asher, W.; Drushka, K.; Schanze, J. J.; Jessup, A. T.; Clark, D.

2016-12-01

Rain can produce a lens of fresher and generally colder, less dense water at the ocean surface. These stable surface layers concentrate heat, freshwater, and momentum into a thin layer and reduce the exchange of these properties between the surface layer and deeper water, which can impact regional freshwater storage and air-sea fluxes of heat and moisture. Although in situ observations have shown that fresh lenses are common in the presence of rain, attempts to correlate the magnitude and lifetime of the surface freshening with rain rate using field data have not produced a definitive relationship. The reasons for this are most likely that in situ rain rate measurements represent the freshwater flux to the ocean surface at a single point in space and time, whereas the fresh lens is the result of the integrated rainfall over time and space, convoluted with the evolution of the fresh lens. Therefore, it is possible that integrated, upstream rainfall estimates might provide a better correlate for the presence of fresh lenses than in situ measurements at a point. This hindcast study seeks to determine the utility of NASA GPM IMERG satellite measurements of rain relative to in situ collocated rain measurements in predicting the occurrence and duration of 0-1 m freshwater stabilization of the ocean. Vertical gradients of temperature, salinity, and density between the surface and at most a few meters were measured using towed profilers and underway sampling during the 2016 SPURS-2 experiment conducted in the tropical east Pacific Ocean. Local wind speed was also measured and taken into account. These measurements were used to determine whether local or integrated upstream precipitation metrics could better predict the occurrence of rain-generated lenses of fresher water at the ocean surface and whether the strength and duration of rain events was correlated with the observed lifetime of fresh lenses.

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

NASA Astrophysics Data System (ADS)

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.

Evaluation of WRF PBL parameterization schemes against direct observations during a dry event over the Ganges valley

NASA Astrophysics Data System (ADS)

Sathyanadh, Anusha; Prabha, Thara V.; Balaji, B.; Resmi, E. A.; Karipot, Anandakumar

2017-09-01

Accurate representations of the planetary boundary layer (PBL) are important in all weather forecast systems, especially in simulations of turbulence, wind and air quality in the lower atmosphere. In the present study, detailed observations from the Cloud Aerosol Interaction and Precipitation Enhancement Experiment - Integrated Ground based Observational Campaign (CAIPEEX-IGOC) 2014 comprising of the complete surface energy budget and detailed boundary layer observations are used to validate Advanced Research Weather Research and Forecasting (WRF) model simulations over a diverse terrain over the Ganges valley region, Uttar Pradesh, India. A drying event in June 2014 associated with a heat wave is selected for validation.Six local and nonlocal PBL schemes from WRF at 1 km resolution are compared with hourly observations during the diurnal cycle. Near-surface observations of weather parameters, radiation components and eddy covariance fluxes from micrometeorological tower, and profiles of variables from microwave radiometer, and radiosonde observations are used for model evaluations. Models produce a warmer, drier surface layer with higher wind speed, sensible heat flux and temperature than observations. Layered boundary layer dynamics, including the residual layer structure as illustrated in the observations over the Ganges valley are missed in the model, which lead to deeper mixed layers and excessive drying.Although it is difficult to identify any single scheme as the best, the qualitative and quantitative analyses for the entire study period and overall reproducibility of the observations indicate that the MYNN2 simulations describe lower errors and more realistic simulation of spatio-temporal variations in the boundary layer height.

Producing Solar Cells By Surface Preparation For Accelerated Nucleation Of Microcrystalline Silicon On Heterogeneous Substrates.

DOEpatents

Yang, Liyou; Chen, Liangfan

1998-03-24

Attractive multi-junction solar cells and single junction solar cells with excellent conversion efficiency can be produced with a microcrystalline tunnel junction, microcrystalline recombination junction or one or more microcrystalline doped layers by special plasma deposition processes which includes plasma etching with only hydrogen or other specified etchants to enhance microcrystalline growth followed by microcrystalline. nucleation with a doped hydrogen-diluted feedstock.

Fabrication of ordered bulk heterojunction organic photovoltaic cells using nanopatterning and electrohydrodynamic spray deposition methods.

PubMed

Park, Sung-Eun; Kim, Sehwan; Kim, Kangmin; Joe, Hang-Eun; Jung, Buyoung; Kim, Eunkyoung; Kim, Woochul; Min, Byung-Kwon; Hwang, Jungho

2012-12-21

Organic photovoltaic cells with an ordered heterojunction (OHJ) active layer are expected to show increased performance. In the study described here, OHJ cells were fabricated using a combination of nanoimprinting and electrohydrodynamic (EHD) spray deposition methods. After an electron donor material was nanoimprinted with a PDMS stamp (valley width: 230 nm, period: 590 nm) duplicated from a Si nanomold, an electron acceptor material was deposited onto the nanoimprinted donor layer using an EHD spray deposition method. The donor-acceptor interface layer was observed by obtaining cross-sectional images with a focused ion beam (FIB) microscope. The photocurrent generation performance of the OHJ cells was evaluated with the current density-voltage curve under air mass (AM) 1.5 conditions. It was found that the surface morphology of the electron acceptor layer affected the current and voltage outputs of the photovoltaic cells. When an electron acceptor layer with a smooth thin (250 nm above the valley of the electron donor layer) surface morphology was obtained, power conversion efficiency was as high as 0.55%. The electrohydrodynamic spray deposition method used to produce OHJ photovoltaic cells provides a means for the adoption of large area, high throughput processes.

Osteoinductive implants: the mise-en-scène for drug-bearing biomimetic coatings.

PubMed

Liu, Y; de Groot, K; Hunziker, E B

2004-03-01

In orthopaedic and dental implantology, novel tools and techniques are being sought to improve the regeneration of bone tissue. Numerous attempts have been made to enhance the osteoconductivity of titanium prostheses, including modifications in their surface properties and coating with layers of calcium phosphate. The technique whereby such layers are produced has recently undergone a revolutionary change, which has had profound consequences for their potential to serve as drug-carrier systems. Hitherto, calcium phosphate layers were deposited upon the surfaces of metal implants under highly unphysiological physical conditions, which precluded the incorporation of proteinaceous osteoinductive drugs. These agents could only be adsorbed, superficially, upon preformed layers. Such superficially adsorbed molecules are released too rapidly within a biological milieu to be effective in their osteoinductive capacity. Now, it is possible to deposit calcium phosphate layers under physiological conditions of temperature and pH by the so-called biomimetic process, during which bioactive agents can be coprecipitated. Since these molecules are integrated into the inorganic latticework, they are released gradually in vivo as the layer undergoes degradation. This feature enhances the capacity of these coatings to act as a carrier system for osteogenic agents.

Effect of pulsed laser parameters on in-situ TiC synthesis in laser surface treatment

NASA Astrophysics Data System (ADS)

Hamedi, M. J.; Torkamany, M. J.; Sabbaghzadeh, J.

2011-04-01

Commercial titanium sheets pre-coated with 300-μm thick graphite layer were treated by employing a pulsed Nd:YAG laser in order to enhance surface properties such as wear and erosion resistance. Laser in-situ alloying method produced a composite layer by melting the titanium substrate and dissolution of graphite in the melt pool. Correlations between pulsed laser parameters, microstructure and microhardness of the synthesized composite coatings were investigated. Effects of pulse duration and overlapping factor on the microstructure and hardness of the alloyed layer were deduced from Vickers micro-indentation tests, XRD, SEM and metallographic analyses of cross sections of the generated layer. Results show that the composite cladding layer was constituted with TiC intermetallic phase between the titanium matrix in particle and dendrite forms. The dendritic morphology of composite layer was changed to cellular grain structure by increasing laser pulse duration and irradiated energy. High values of the measured hardness indicate that deposited titanium carbide increases in the conditions with more pulse duration and low process speed. This occurs due to more dissolution of carbon into liquid Ti by heat input increasing and positive influence of the Marangoni flow in the melted zone.

Dry sliding wear behavior of TIG welding clad WC composite coatings

NASA Astrophysics Data System (ADS)

Buytoz, Soner; Ulutan, Mustafa; Yildirim, M. Mustafa

2005-12-01

In this study, melted tungsten carbide powders on the surface of AISI 4340 steel was applied by using tungsten inert gas (TIG) method. It was observed that it has been solidified in different microstructures depending on the production parameters. As a result of microstructure examinations, in the surface modified layers an eutectic and dendrite solidification was observed together with WC, W 2C phases. In the layer produced, the hardness values varied between 950 and 1200 HV. The minimum mass loss was observed in the sample, which was treated in 1.209 mm/s production rate, 0.5 g/s powder feed rate and 13.9 kJ/cm heat input.

Photographer : JPL Range : 12 million km. ( 7.56 million miles) P-23057C & BW This Voyager 1

NASA Technical Reports Server (NTRS)

1980-01-01

Photographer : JPL Range : 12 million km. ( 7.56 million miles) P-23057C & BW This Voyager 1 photograph of Titan, the largest of Saturn's 14 known satellites, shows little more than the upper layers of clouds covering the moon. The orange colored haze, is believed to be composed of photochemically produced hydrocarbons, hides Titan's solid surface from Voyager's camera. Some weak shadings in the clouds are becoming visible. However, note that the satellite's southern, lower, hemisphere is brighter than the northern. It is not known whether these subtle shadings are on the surface or are due to clouds below a high haze layer.

Effect of Strong Acid Functional Groups on Electrode Rise Potential in Capacitive Mixing by Double Layer Expansion

DOE PAGES

Hatzell, Marta C.; Raju, Muralikrishna; Watson, Valerie J.; ...

2014-11-03

We report that the amount of salinity-gradient energy that can be obtained through capacitive mixing based on double layer expansion depends on the extent the electric double layer (EDL) is altered in a low salt concentration (LC) electrolyte (e.g., river water). We show that the electrode-rise potential, which is a measure of the EDL perturbation process, was significantly (P = 10 –5) correlated to the concentration of strong acid surface functional groups using five types of activated carbon. Electrodes with the lowest concentration of strong acids (0.05 mmol g –1) had a positive rise potential of 59 ± 4 mVmore » in the LC solution, whereas the carbon with the highest concentration (0.36 mmol g –1) had a negative rise potential (₋31 ± 5 mV). Chemical oxidation of a carbon (YP50) using nitric acid decreased the electrode rise potential from 46 ± 2 mV (unaltered) to ₋6 ± 0.5 mV (oxidized), producing a whole cell potential (53 ± 1.7 mV) that was 4.4 times larger than that obtained with identical electrode materials (from 12 ± 1 mV). Changes in the EDL were linked to the behavior of specific ions in a LC solution using molecular dynamics and metadynamics simulations. The EDL expanded in the LC solution when a carbon surface (pristine graphene) lacked strong acid functional groups, producing a positive-rise potential at the electrode. In contrast, the EDL was compressed for an oxidized surface (graphene oxide), producing a negative-rise electrode potential. In conclusion, these results established the linkage between rise potentials and specific surface functional groups (strong acids) and demonstrated on a molecular scale changes in the EDL using oxidized or pristine carbons.« less

Amorphous surface layers in Ti-implanted Fe

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

1979-01-01

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

Providing the Efficiency and Dispersion Characteristics of Aerosols in Ultrasonic Atomization

NASA Astrophysics Data System (ADS)

Khmelev, V. N.; Shalunov, A. V.; Golykh, R. N.; Nesterov, V. A.; Dorovskikh, R. S.; Shalunova, A. V.

2017-07-01

This article is devoted to the investigation of the process of atomization of liquids under the action of ultrasonic vibrations. It has been shown that the ultrasonic atomization parameters are determined by the regimes of action (vibration frequency and amplitude of the atomization surface), the liquid properties (viscosity, surface tension), and the thickness of the liquid layer covering the atomization surface. To reveal the dependences of the efficiency of the process at various dispersion characteristics of produced liquid droplets, we propose a model based on the cavitation-wave theory of droplet formation. The obtained results can be used in designing and using ultrasonic atomizers producing an aerosol with characteristics complying with the requirements on efficiency and dispersivity for the process being realized.

Promotion of dropwise condensation of ethyl alcohol, methyl alcohol, and acetone by polytetrafluoroethylene

NASA Technical Reports Server (NTRS)

Kirby, C. E.

1972-01-01

Coating condensing surfaces with thin layer of nonpolar Teflon results in dropwise condensation of polar organic vapor. Greater heat transfer coefficients are produced increasing effectiveness of condensing system. Investigation shows that vapors with strong dipole moment tend to condense dropwise.

Evidence of circular Rydberg states in beam-foil experiments: Role of the surface wake field

NASA Astrophysics Data System (ADS)

Sharma, Gaurav; Puri, Nitin K.; Kumar, Pravin; Nandi, T.

2017-12-01

We have employed the concept of the surface wake field to model the formation of the circular Rydberg states in the beam-foil experiments. The experimental studies of atomic excitation processes show the formation of circular Rydberg states either in the bulk of the foil or at the exit surface, and the mechanism is explained by several controversial theories. The present model is based on the interesting fact that the charge state fraction as well as the surface wake field depend on the foil thickness and it resolves a long-standing discrepancy on the mechanism of the formation of circular Rydberg states. The influence of exit layers is twofold. Initially, the high angular momentum Rydberg states are produced in the last layers of the foil by the Stark switching due to the bulk wake field and finally, they are transferred to the circular Rydberg states as a single multiphoton process due to the influence of the surface wake field.

Simulating and validating coastal gradients in wind energy resources

NASA Astrophysics Data System (ADS)

Hahmann, Andrea; Floors, Rogier; Karagali, Ioanna; Vasiljevic, Nikola; Lea, Guillaume; Simon, Elliot; Courtney, Michael; Badger, Merete; Peña, Alfredo; Hasager, Charlotte

2016-04-01

The experimental campaign of the RUNE (Reducing Uncertainty of Near-shore wind resource Estimates) project took place on the western coast of Denmark during the winter 2015-2016. The campaign used onshore scanning lidar technology combined with ocean and satellite information and produced a unique dataset to study the transition in boundary layer dynamics across the coastal zone. The RUNE project aims at reducing the uncertainty of near-shore wind resource estimates produced by mesoscale modeling. With this in mind, simulations using the Weather Research and Forecasting (WRF) model were performed to identify the sensitivity in the coastal gradients of wind energy resources to various model parameters and model inputs. Among these: model horizontal grid spacing and the planetary boundary layer and surface-layer scheme. We report on the differences amongst these simulations and preliminary results on the comparison of the model simulations with the RUNE observations of lidar and satellite measurements and near coastal tall mast.

Apparent thermal inertia and the surface heterogeneity of Mars

NASA Astrophysics Data System (ADS)

Putzig, Nathaniel E.; Mellon, Michael T.

2007-11-01

Thermal inertia derivation techniques generally assume that surface properties are uniform at horizontal scales below the footprint of the observing instrument and to depths of several decimeters. Consequently, surfaces with horizontal or vertical heterogeneity may yield apparent thermal inertia which varies with time of day and season. To investigate these temporal variations, we processed three Mars years of Mars Global Surveyor Thermal Emission Spectrometer observations and produced global nightside and dayside seasonal maps of apparent thermal inertia. These maps show broad regions with diurnal and seasonal differences up to 200 J m -2 K -1s -1/2 at mid-latitudes (60° S to 60° N) and 600 J m -2 K -1s -1/2 or greater in the polar regions. We compared the seasonal mapping results with modeled apparent thermal inertia and created new maps of surface heterogeneity at 5° resolution, delineating regions that have thermal characteristics consistent with horizontal mixtures or layers of two materials. The thermal behavior of most regions on Mars appears to be dominated by layering, with upper layers of higher thermal inertia (e.g., duricrusts or desert pavements over fines) prevailing in mid-latitudes and upper layers of lower thermal inertia (e.g., dust-covered rock, soils with an ice table at shallow depths) prevailing in polar regions. Less common are regions dominated by horizontal mixtures, such as those containing differing proportions of rocks, sand, dust, and duricrust or surfaces with divergent local slopes. Other regions show thermal behavior that is more complex and not well-represented by two-component surface models. These results have important implications for Mars surface geology, climate modeling, landing-site selection, and other endeavors that employ thermal inertia as a tool for characterizing surface properties.

Self-assembled monolayer structures of hexadecylamine on Cu surfaces: density-functional theory.

PubMed

Liu, Shih-Hsien; Balankura, Tonnam; Fichthorn, Kristen A

2016-12-07

We used dispersion-corrected density-functional theory to probe possible structures for adsorbed layers of hexadecylamine (HDA) on Cu(100) and Cu(111). HDA forms self-assembled layers on these surfaces, analogous to alkanethiols on various metal surfaces, and it binds by donating electrons in the amine group to the Cu surface atoms, consistent with experiment. van der Waals interactions between the alkyl tails of HDA molecules are stronger than the interaction between the amine group and the Cu surfaces. Strong HDA-tail interactions lead to coverage-dependent tilting of the HDA layers, such that the tilt angle is larger for lower coverages. At full monolayer coverage, the energetically preferred binding configuration for HDA on Cu(100) is a (5 × 3) pattern - although we cannot rule out incommensurate structures - while the pattern is preferred on Cu(111). A major motivation for this study is to understand the experimentally observed capability of HDA as a capping agent for producing {100}-faceted Cu nanocrystals. Consistent with experiment, we find that HDA binds more strongly to Cu(100) than to Cu(111). This strong binding stems from the capability of HDA to form more densely packed layers on Cu(100), which leads to stronger HDA-tail interactions, as well as the stronger binding of the amine group to Cu(100). We estimate the surface energies of HDA-covered Cu(100) and Cu(111) surfaces and find that these surfaces are nearly isoenergetic. By drawing analogies to previous theoretical work, it seems likely that HDA-covered Cu nanocrystals could have kinetic shapes that primarily express {100} facets, as is seen experimentally.

Heat and turbulent kinetic energy budgets for surface layer cooling induced by the passage of Hurricane Frances (2004)

NASA Astrophysics Data System (ADS)

Huang, Peisheng; Sanford, Thomas B.; Imberger, JöRg

2009-12-01

Heat and turbulent kinetic energy budgets of the ocean surface layer during the passage of Hurricane Frances were examined using a three-dimensional hydrodynamic model. In situ data obtained with the Electromagnetic-Autonomous Profiling Explorer (EM-APEX) floats were used to set up the initial conditions of the model simulation and to compare to the simulation results. The spatial heat budgets reveal that during the hurricane passage, not only the entrainment in the bottom of surface mixed layer but also the horizontal water advection were important factors determining the spatial pattern of sea surface temperature. At the free surface, the hurricane-brought precipitation contributed a negligible amount to the air-sea heat exchange, but the precipitation produced a negative buoyancy flux in the surface layer that overwhelmed the instability induced by the heat loss to the atmosphere. Integrated over the domain within 400 km of the hurricane eye on day 245.71 of 2004, the rate of heat anomaly in the surface water was estimated to be about 0.45 PW (1 PW = 1015 W), with about 20% (0.09 PW in total) of this was due to the heat exchange at the air-sea interface, and almost all the remainder (0.36 PW) was downward transported by oceanic vertical mixing. Shear production was the major source of turbulent kinetic energy amounting 88.5% of the source of turbulent kinetic energy, while the rest (11.5%) was attributed to the wind stirring at sea surface. The increase of ocean potential energy due to vertical mixing represented 7.3% of the energy deposited by wind stress.

Preparation of Gelatin Layer Film with Gold Clusters in Using Photographic Film

NASA Astrophysics Data System (ADS)

Kuge, Ken'ichi; Arisawa, Michiko; Aoki, Naokazu; Hasegawa, Akira

2000-12-01

A gelatin layer film with gold clusters is produced by taking advantage of the photosensitivity of silver halide photography. Through exposure silver specks, which are called latent-image specks and are composed of several reduced silver atoms, are formed on the surface of silver halide grains in the photographic film. As the latent-image specks act as a catalyst for redox reaction, reduced gold atoms are deposited on the latent-image specks when the exposed film is immersed in a gold (I) thiocyanate complex solution for 5-20 days. Subsequently, when the silver halide grains are dissolved and removed, the gelatin layer film with gold clusters remains. The film produced by this method is purple and showed an absorption spectrum having a maximum of approximately 560 nm as a result of plasmon absorption. The clusters continued to grow with immersion time, and the growth rate increased as the concentration of the gold complex solution was increased. The cluster diameter changed from 20 nm to 100 nm. By this method, it is possible to produce a gelatin film of a large area with evenly dispersed gold clusters, and since it is produced only on the exposed area, pattern forming is also possible.

Intermetallic Compound Growth between Electroless Nickel/Electroless Palladium/Immersion Gold Surface Finish and Sn-3.5Ag or Sn-3.0Ag-0.5Cu Solder

NASA Astrophysics Data System (ADS)

Oda, Yukinori; Fukumuro, Naoki; Yae, Shinji

2018-04-01

Using an electroless nickel/electroless palladium/immersion gold (ENEPIG) surface finish with a thick palladium-phosphorus (Pd-P) layer of 1 μm, the intermetallic compound (IMC) growth between the ENEPIG surface finish and lead-free solders Sn-3.5Ag (SA) or Sn-3.0Ag-0.5Cu (SAC) after reflow soldering and during solid-state aging at 150°C was investigated. After reflow soldering, in the SA/ENEPIG and SAC/ENEPIG interfaces, thick PdSn4 layers of about 2 μm to 3 μm formed on the residual Pd-P layers ( 0.5 μm thick). On the SA/ENEPIG interface, Sn was detected on the upper side of the residual Pd-P layer. On the SAC/ENEPIG interface, no Sn was detected in the residual Pd-P layer, and Cu was detected in the interface between the Pd-P and PdSn4 layers. After 300 h of aging at 150°C, the residual Pd-P layers had diffused completely into the solders. In the SA/ENEPIG interface, an IMC layer consisting of Ni3Sn4 and Ni3SnP formed between the PdSn4 layer and the nickel-phosphorus (Ni-P) layer, and a (Pd,Ni)Sn4 layer formed on the lower side of the PdSn4 layer. On the SAC/ENEPIG interface, a much thinner (Pd,Ni)Sn4 layer was observed, and a (Cu,Ni)6Sn5 layer was observed between the PdSn4 and Ni-P layers. These results indicate that Ni diffusion from the Ni-P layer to the PdSn4 layer produced a thick (Pd,Ni)Sn4 layer in the SA solder case, but was prevented by formation of (Cu,Ni)6Sn5 in the SAC solder case. This causes the difference in solder joint reliability between SA/ENEPIG and SAC/ENEPIG interfaces in common, thin Pd-P layer cases.

Roman sophisticated surface modification methods to manufacture silver counterfeited coins

NASA Astrophysics Data System (ADS)

Ingo, G. M.; Riccucci, C.; Faraldi, F.; Pascucci, M.; Messina, E.; Fierro, G.; Di Carlo, G.

2017-11-01

By means of the combined use of X-ray photoelectron spectroscopy (XPS), optical microscopy (OM) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) the surface and subsurface chemical and metallurgical features of silver counterfeited Roman Republican coins are investigated to decipher some aspects of the manufacturing methods and to evaluate the technological ability of the Roman metallurgists to produce thin silver coatings. The results demonstrate that over 2000 ago important advances in the technology of thin layer deposition on metal substrates were attained by Romans. The ancient metallurgists produced counterfeited coins by combining sophisticated micro-plating methods and tailored surface chemical modification based on the mercury-silvering process. The results reveal that Romans were able systematically to chemically and metallurgically manipulate alloys at a micro scale to produce adherent precious metal layers with a uniform thickness up to few micrometers. The results converge to reveal that the production of forgeries was aimed firstly to save expensive metals as much as possible allowing profitable large-scale production at a lower cost. The driving forces could have been a lack of precious metals, an unexpected need to circulate coins for trade and/or a combinations of social, political and economic factors that requested a change in money supply. Finally, some information on corrosion products have been achieved useful to select materials and methods for the conservation of these important witnesses of technology and economy.

A Facile All-Solution-Processed Surface with High Water Contact Angle and High Water Adhesive Force.

PubMed

Chen, Mei; Hu, Wei; Liang, Xiao; Zou, Cheng; Li, Fasheng; Zhang, Lanying; Chen, Feiwu; Yang, Huai

2017-07-12

A series of sticky superhydrophobicity surfaces with high water contact angle and high water adhesive force is facilely prepared via an all-solution-processed method based on polymerization-induced phase separation between liquid crystals (LCs) and epoxy resin, which produces layers of epoxy microspheres (EMSs) with nanofolds on the surface of a substrate. The morphologies and size distributions of EMSs are confirmed by scanning electron microscopy. Results reveal that the obtained EMS coated-surface exhibits high apparent contact angle of 152.0° and high water adhesive force up to 117.6 μN. By varying the composition of the sample or preparing conditions, the sizes of the produced EMSs can be artificially regulated and, thus, control the wetting properties and water adhesive behaviors. Also, the sticky superhydrophobic surface exhibits excellent chemical stability, as well as long-term durability. Water droplet transportation experiments further prove that the as-made surface can be effectively used as a mechanical hand for water transportation applications. Based on this, it is believed that the simple method proposed in this paper will pave a new way for producing a sticky superhydrophobic surface and obtain a wide range of use.

Uniform hydrogen fuel layers for inertial fusion targets by microgravity

NASA Technical Reports Server (NTRS)

Parks, P. B.; Fagaly, Robert L.

1994-01-01

A critical concern in the fabrication of targets for inertial confinement fusion (ICF) is ensuring that the hydrogenic (D(sub 2) or DT) fuel layer maintains spherical symmetry. Solid layered targets have structural integrity, but lack the needed surface smoothness. Liquid targets are inherently smooth, but suffer from gravitationally induced sagging. One method to reduce the effective gravitational field environment is freefall insertion into the target chamber. Another method to counterbalance field gravitational force is to use an applied magnetic field combined with a gradient field to induce a magnetic dipole force on the liquid fuel layer. Based on time dependent calculations of the dynamics of the liquid fuel layer in microgravity environments, we show that it may be possible to produce a liquid layered ICF target that satisfies both smoothness and symmetry requirements.

Performance of WRF in simulating terrain induced flows and atmospheric boundary layer characteristics over the tropical station Gadanki

NASA Astrophysics Data System (ADS)

Hari Prasad, K. B. R. R.; Srinivas, C. V.; Rao, T. Narayana; Naidu, C. V.; Baskaran, R.

2017-03-01

In this study the evolution of the topographic flows and boundary layer features over a tropical hilly station Gadanki in southern India were simulated using Advanced Research WRF (ARW) mesoscale model for fair weather days during southwest monsoon (20-22 July 2011) and winter (18-20 Jan. 2011). Turbulence measurements from an Ultra High Frequency (UHF) Wind Profiler, Ultra Sonic Anemometer, GPS Sonde and meteorological tower were used for comparison. Simulations revealed development of small-scale slope winds in the lower boundary layer (below 800 m) at Gadanki which are more prevalent during nighttime. Stronger slope winds during winter and weaker flows in the monsoon season are simulated indicating the sensitivity of slope winds to the background synoptic flows and radiative heating/cooling. Higher upward surface fluxes (sensible, latent heat) and development of very deep convective boundary layer ( 2500 m) is simulated during summer monsoon relative to the winter season in good agreement with observations. Four PBL parameterizations (YSU, MYJ, MYNN and ACM) were evaluated to simulate the above characteristics. Large differences were noticed in the simulated boundary layer features using different PBL schemes in both the seasons. It is found that the TKE-closures (MYJ, MYNN) produced extremities in daytime PBL depth, surface fluxes, temperature, humidity and winds. The differences in the simulations are attributed to the eddy diffusivities, buoyancy and entrainment fluxes which were simulated differently in the respective schemes. The K-based YSU followed by MYNN best produced the slope winds as well as daytime boundary layer characteristics realistically in both the summer and winter synoptic conditions at Gadanki hilly site though with slight overestimation of nocturnal PBL height.

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

PubMed Central

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

2015-01-01

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

Characterization of damage modes in dental ceramic bilayer structures.

PubMed

Deng, Yan; Lawn, Brian R; Lloyd, Isabel K

2002-01-01

Results of contact tests using spherical indenters on flat ceramic coating layers bonded to compliant substrates are reported for selected dental ceramics. Critical loads to produce various damage modes, cone cracking, and quasiplasticity at the top surfaces and radial cracking at the lower (inner) surfaces are measured as a function of ceramic-layer thickness. It is proposed that these damage modes, especially radial cracking, are directly relevant to the failure of all-ceramic dental crowns. The critical load data are analyzed with the use of explicit fracture-mechanics relations, expressible in terms of routinely measurable material parameters (elastic modulus, strength, toughness, hardness) and essential geometrical variables (layer thickness, contact radius). The utility of such analyses in the design of ceramic/substrate bilayer systems for optimal resistance to lifetime-threatening damage is discussed. Copyright 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 137--145, 2002; DOI 10.1002/jbm.10091

Sound radiation due to boundary layer transition

NASA Technical Reports Server (NTRS)

Wang, Meng

1993-01-01

This report describes progress made to date towards calculations of noise produced by the laminar-turbulence transition process in a low Mach number boundary layer formed on a rigid wall. The primary objectives of the study are to elucidate the physical mechanisms by which acoustic waves are generated, to clarify the roles of the fluctuating Reynolds stress and the viscous stress in the presence of a solid surface, and to determine the relative efficiency as a noise source of the various transition stages. In particular, we will examine the acoustic characteristics and directivity associated with three-dimensional instability waves, the detached high-shear layer, and turbulent spots following a laminar breakdown. Additionally, attention will be paid to the unsteady surface pressures during the transition, which provide a source of flow noise as well as a forcing function for wall vibration in both aeronautical and marine applications.

In-situ laser nano-patterning for ordered InAs/GaAs(001) quantum dot growth

NASA Astrophysics Data System (ADS)

Zhang, Wei; Shi, Zhenwu; Huo, Dayun; Guo, Xiaoxiang; Zhang, Feng; Chen, Linsen; Wang, Qinhua; Zhang, Baoshun; Peng, Changsi

2018-04-01

A study of in-situ laser interference nano-patterning on InGaAs wetting layers was carried out during InAs/GaAs (001) quantum dot molecular beam epitaxy growth. Periodic nano-islands with heights of a few atomic layers were obtained via four-beam laser interference irradiation on the InGaAs wetting layer at an InAs coverage of 0.9 monolayer. The quantum dots nucleated preferentially at edges of nano-islands upon subsequent deposition of InAs on the patterned surface. When the nano-islands are sufficiently small, the patterned substrate could be spontaneously re-flattened and an ordered quantum dot array could be produced on the smooth surface. This letter discusses the mechanisms of nano-patterning and ordered quantum dot nucleation in detail. This study provides a potential technique leading to site-controlled, high-quality quantum dot fabrication.

Processing of materials for uniform field emission

DOEpatents

Pam, L.S.; Felter, T.E.; Talin, A.; Ohlberg, D.; Fox, C.; Han, S.

1999-01-12

This method produces a field emitter material having a uniform electron emitting surface and a low turn-on voltage. Field emitter materials having uniform electron emitting surfaces as large as 1 square meter and turn-on voltages as low as 16V/{micro}m can be produced from films of electron emitting materials such as polycrystalline diamond, diamond-like carbon, graphite and amorphous carbon by the method of the present invention. The process involves conditioning the surface of a field emitter material by applying an electric field to the surface, preferably by scanning the surface of the field emitter material with an electrode maintained at a fixed distance of at least 3 {micro}m above the surface of the field emitter material and at a voltage of at least 500V. In order to enhance the uniformity of electron emission the step of conditioning can be preceded by ion implanting carbon, nitrogen, argon, oxygen or hydrogen into the surface layers of the field emitter material. 2 figs.

Processing of materials for uniform field emission

DOEpatents

Pam, Lawrence S.; Felter, Thomas E.; Talin, Alec; Ohlberg, Douglas; Fox, Ciaran; Han, Sung

1999-01-01

This method produces a field emitter material having a uniform electron emitting surface and a low turn-on voltage. Field emitter materials having uniform electron emitting surfaces as large as 1 square meter and turn-on voltages as low as 16V/.mu.m can be produced from films of electron emitting materials such as polycrystalline diamond, diamond-like carbon, graphite and amorphous carbon by the method of the present invention. The process involves conditioning the surface of a field emitter material by applying an electric field to the surface, preferably by scanning the surface of the field emitter material with an electrode maintained at a fixed distance of at least 3 .mu.m above the surface of the field emitter material and at a voltage of at least 500V. In order to enhance the uniformity of electron emission the step of conditioning can be preceeded by ion implanting carbon, nitrogen, argon, oxygen or hydrogen into the surface layers of the field emitter material.

Modeling the diurnal cycle of carbon monoxide: Sensitivity to physics, chemistry, biology, and optics

NASA Astrophysics Data System (ADS)

Gnanadesikan, Anand

1996-05-01

As carbon monoxide within the oceanic surface layer is produced by solar radiation, diluted by mixing, consumed by biota, and outgassed to the atmosphere, it exhibits a diurnal cycle. The effect of dilution and mixing on this cycle is examined using a simple model for production and consumption, coupled to three different mixed layer models. The magnitude and timing of the peak concentration, the magnitude of the average concentration, and the air-sea flux are considered. The models are run through a range of heating and wind stress and compared to experimental data reported by Kettle [1994]. The key to the dynamics is the relative size of four length scales; Dmix, the depth to which mixing occurs over the consumption time; L, the length scale over which production occurs; Lout, the depth to which the mixed layer is ventilated over the consumption time; and Lcomp, the depth to which the diurnal production can maintain a concentration in equilibrium with the atmosphere. If Dmix ≫ L, the actual model parameterization can be important. If the mixed layer is maintained by turbulent diffusion, Dmix can be substantially less than the mixed layer depth. If the mixed layer is parameterized as a homogeneous slab, Dmix is equivalent to the mixed layer depth. If Dmix > Lout, production is balanced by consumption rather than outgassing. The ratio between Dmix and Lcomp determines whether the ocean is a source or a sink for CO. The main thermocline depth H sets an upper limit for Dmix and hence Dmix/L, Dmix/Lout, and Dmix/Lcomp. The models are run to simulate a single day of observations. The mixing parameterization is shown to be very important, with a model which mixes using small-scale diffusion, producing markedly larger surface concentrations than models which homogenize the mixed layer completely and instantaneously.

Nanoengineered Plasmonic Hybrid Systems for Bio-nanotechnology

NASA Astrophysics Data System (ADS)

Leong, Kirsty

Plasmonic hybrid systems are fabricated using a combination of lithography and layer-by-layer directed self-assembly approaches to serve as highly sensitive nanosensing devices. This layer-by-layer directed self-assembly approach is utilized as a hybrid methodology to control the organization of quantum dots (QDs), nanoparticles, and biomolecules onto inorganic nanostructures with site-specific attachment and functionality. Here, surface plasmon-enhanced nanoarrays are fabricated where the photoluminescence of quantum dots and conjugated polymer nanoarrays are studied. This study was performed by tuning the localized surface plasmon resonance and the distance between the emitter and the metal surface using genetically engineered polypeptides as binding agents and biotin-streptavidin binding as linker molecules. In addition, these nanoarrays were also chemically modified to support the immobilization and label-free detection of DNA using surface enhanced Raman scattering. The surface of the nanoarrays was chemically modified using an acridine containing molecule which can act as an intercalating agent for DNA. The self-assembled monolayer (SAM) showed the ability to immobilize and intercalate DNA onto the surface. This SAM system using surface enhanced Raman scattering (SERS) serves as a highly sensitive methodology for the immobilization and label-free detection of DNA applicable into a wide range of bio-diagnostic platforms. Other micropatterned arrays were also fabricated using a combination of soft lithography and surface engineering. Selective single cell patterning and adhesion was achieved through chemical modifications and surface engineering of poly(dimethylsiloxane) surface. The surface of each microwell was functionally engineered with a SAM which contained an aldehyde terminated fused-ring aromatic thiolated molecule. Cells were found to be attracted and adherent to the chemically modified microwells. By combining soft lithography and surface engineering, a simple methodology produced single cell arrays on biocompatible substrates. Thus the design of plasmonic devices relies heavily on the nature of the plasmonic interactions between nanoparticles in the devices which can potentially be fabricated into lab-on-a-chip devices for multiplex sensing capabilities.

Method utilizing laser-processing for the growth of epitaxial p-n junctions

DOEpatents

Young, R.T.; Narayan, J.; Wood, R.F.

1979-11-23

This invention is a new method for the formation of epitaxial p-n junctions in silicon. The method is relatively simple, rapid, and reliable. It produces doped epitaxial layers which are of well-controlled thickness and whose electrical properties are satisfactory. An illustrative form of the method comprises co-depositing a selected dopant and amorphous silicon on a crystalline silicon substrate to form a doped layer of amorphous silicon thereon. This layer then is irradiated with at least one laser pulse to generate a melt front which moves through the layer, into the silicon body to a depth effecting melting of virginal silicon, and back to the surface of the layer. The method may be conducted with dopants (e.g., boron and phosphorus) whose distribution coefficients approximate unity.

Preparation and characterization of coating sodium trisilicate (Na2O.nSiO2) at calcium carbonate (CaCO3) for blowing agent in Mg alloy foam

NASA Astrophysics Data System (ADS)

Erryani, Aprilia; Lestari, Franciska Pramuji; Annur, Dhyah; Kartika, Ika

2018-05-01

The role of blowing agent in the manufacture of porous metal alloys is very important to produce the desired pore. The thermal stability and speed of foam formation have an effect on the resulting pore structure. In porous metal alloys, uniformity of size and pore deployment are the main determinants of the resulting alloys. The coating process of calcium carbonate (CaCO3) has been done using Sodium trisilicate solution by sol-gel method. Foaming agent was pretreated by coating SiO2 passive layer on the surface of CaCO3. This coating aims to produce a more stable blowing agent so that the foaming process can produce a more uniform pore size. The microstructure of the SiO2 passive was observed using Scanning Electron Microscope (SEM) equipped by Energy Dispersive X-Ray Spectrometer (EDS) mapping. The results showed coating CaCO3 using sodium trisilicate was successfully done creating a passive layer of SiO2 on the surface of CaCO3. By the coating process, the thermal stability of coated CaCO3 increased compared to uncoated CaCO3.

Process Evaluation of AISI 4340 Steel Manufactured by Laser Powder Bed Fusion

NASA Astrophysics Data System (ADS)

Jelis, Elias; Hespos, Michael R.; Ravindra, Nuggehalli M.

2018-01-01

Laser powder bed fusion (L-PBF) involves the consolidation of metal powder, layer by layer, through laser melting and solidification. In this study, process parameters are optimized for AISI 4340 steel to produce dense and homogeneous structures. The optimized process parameters produce mechanical properties at the center of the build plate that are comparable to wrought in the vertical and horizontal orientations after heat treatment and machining. Four subsequent builds are filled with specimens to evaluate the mechanical behavior as a function of location and orientation. Variations in the mechanical properties are likely due to recoater blade interactions with the powder and uneven gas flow. The results obtained in this study are analyzed to assess the reliability and reproducibility of the process. A different build evaluates the performance of near-net-shaped tensile specimens angled 35°-90° from the build plate surface (horizontal). Ductility measurements and surface roughness vary significantly as a function of the build angle. In the stress-relieved and as-built conditions, the mechanical behavior of vertically oriented specimens exhibits somewhat lower and more variable ductility than horizontally oriented specimens. Therefore, several process variables affect the mechanical properties of parts produced by the L-PBF process.

Growth of Fault-Cored Anticlines by Flexural Slip Folding: Analysis by Boundary Element Modeling

NASA Astrophysics Data System (ADS)

Johnson, Kaj M.

2018-03-01

Fault-related folds develop due to a combination of slip on the associated fault and distributed deformation off the fault. Under conditions that are sufficient for sedimentary layering to act as a stack of mechanical layers with contact slip, buckling can dramatically amplify the folding process. We develop boundary element models of fault-related folding of viscoelastic layers embedded with a reverse fault to examine the influence of such layering on fold growth. The strength of bedding contacts, the thickness and stiffness of layering, and fault geometry all contribute significantly to the resulting fold form. Frictional contact strength between layers controls the degree of localization of slip within fold limbs; high contact friction in relatively thin bedding tends to localize bedding slip within narrow kink bands on fold limbs, and low contact friction tends to produce widespread bedding slip and concentric fold form. Straight ramp faults tend to produce symmetric folds, whereas listric faults tend to produce asymmetric folds with short forelimbs and longer backlimbs. Fault-related buckle folds grow exponentially with time under steady loading rates. At early stages of folding, fold growth is largely attributed to slip on the fault, but as the fold increases amplitude, a larger portion of the fold growth is attributed to distributed slip across bedding contacts on the limbs of the fold. An important implication for geologic and earthquake studies is that not all surface deformation associated with blind reverse faults may be attributed to slip on the fault during earthquakes.

Solid state radiative heat pump

DOEpatents

Berdahl, Paul H.

1986-01-01

A solid state radiative heat pump (10, 50, 70) operable at room temperature (300.degree. K.) utilizes a semiconductor having a gap energy in the range of 0.03-0.25 eV and operated reversibly to produce an excess or deficit of charge carriers as compared to thermal equilibrium. In one form of the invention (10, 70) an infrared semiconductor photodiode (21, 71) is used, with forward or reverse bias, to emit an excess or deficit of infrared radiation. In another form of the invention (50), a homogeneous semiconductor (51) is subjected to orthogonal magnetic and electric fields to emit an excess or deficit of infrared radiation. Three methods of enhancing transmission of radiation through the active surface of the semiconductor are disclosed. In one method, an anti-reflection layer (19) is coated into the active surface (13) of the semiconductor (11), the anti-reflection layer (19) having an index of refraction equal to the square root of that of the semiconductor (11). In the second method, a passive layer (75) is spaced from the active surface (73) of the semiconductor (71) by a submicron vacuum gap, the passive layer having an index of refractive equal to that of the semiconductor. In the third method, a coupler (91) with a paraboloid reflecting surface (92) is in contact with the active surface (13, 53) of the semiconductor (11, 51), the coupler having an index of refraction about the same as that of the semiconductor.

Boundary-layer receptivity due to distributed surface imperfections of a deterministic or random nature

NASA Technical Reports Server (NTRS)

Choudhari, Meelan

1992-01-01

Acoustic receptivity of a Blasius boundary layer in the presence of distributed surface irregularities is investigated analytically. It is shown that, out of the entire spatial spectrum of the surface irregularities, only a small band of Fourier components can lead to an efficient conversion of the acoustic input at any given frequency to an unstable eigenmode of the boundary layer flow. The location, and width, of this most receptive band of wavenumbers corresponds to a relative detuning of O(R sub l.b.(exp -3/8)) with respect to the lower-neutral instability wavenumber at the frequency under consideration, R sub l.b. being the Reynolds number based on a typical boundary-layer thickness at the lower branch of the neutral stability curve. Surface imperfections in the form of discrete mode waviness in this range of wavenumbers lead to initial instability amplitudes which are O(R sub l.b.(exp 3/8)) larger than those caused by a single, isolated roughness element. In contrast, irregularities with a continuous spatial spectrum produce much smaller instability amplitudes, even compared to the isolated case, since the increase due to the resonant nature of the response is more than that compensated for by the asymptotically small band-width of the receptivity process. Analytical expressions for the maximum possible instability amplitudes, as well as their expectation for an ensemble of statistically irregular surfaces with random phase distributions, are also presented.

3D Dynamics of the Near-Surface Layer of the Ocean in the Presence of Freshwater Influx

NASA Astrophysics Data System (ADS)

Dean, C.; Soloviev, A.

2015-12-01

Freshwater inflow due to convective rains or river runoff produces lenses of freshened water in the near surface layer of the ocean. These lenses are localized in space and typically involve both salinity and temperature anomalies. Due to significant density anomalies, strong pressure gradients develop, which result in lateral spreading of freshwater lenses in a form resembling gravity currents. Gravity currents inherently involve three-dimensional dynamics. The gravity current head can include the Kelvin-Helmholtz billows with vertical density inversions. In this work, we have conducted a series of numerical experiments using computational fluid dynamics tools. These numerical simulations were designed to elucidate the relationship between vertical mixing and horizontal advection of salinity under various environmental conditions and potential impact on the pollution transport including oil spills. The near-surface data from the field experiments in the Gulf of Mexico during the SCOPE experiment were available for validation of numerical simulations. In particular, we observed a freshwater layer within a few-meter depth range and, in some cases, a density inversion at the edge of the freshwater lens, which is consistent with the results of numerical simulations. In conclusion, we discuss applicability of these results to the interpretation of Aquarius and SMOS sea surface salinity satellite measurements. The results of this study indicate that 3D dynamics of the near-surface layer of the ocean are essential in the presence of freshwater inflow.

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

NASA Astrophysics Data System (ADS)

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 <200 nm mainly composed of bioactive sodium titanate and rutile phases of TiO2 covered the interior and exterior of porous titanium 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.

Highly monodisperse multiple twinned AuCu-Pt trimetallic nanoparticles with high index surfaces.

PubMed

Khanal, Subarna; Bhattarai, Nabraj; McMaster, David; Bahena, Daniel; Velazquez-Salazar, J Jesus; Jose-Yacaman, Miguel

2014-08-14

Trimetallic nanoparticles possess different properties than their mono- and bi-metallic counterparts, opening a wide range of possibilities for diverse potential applications with the notion to study possible morphology, atomic ordering, reduce precious metal consumption and many others. In this paper, we present a comprehensive experimental study on AuCu-Pt trimetallic nanoparticles with an average diameter of 15 ± 1.0 nm, synthesized in a one-pot synthesis method and characterized by the Cs-corrected scanning transmission electron microscopy technique that allowed us to probe the structure at the atomic level resolution. A new way to control the nanoparticle morphology by the presence of third metal (Pt) is also discussed by the overgrowth of Pt on the as prepared AuCu core by Frank-van der Merwe (FM) layer-by-layer and Stranski-Krastanov (SK) island-on-wetting-layer growth modes. With the application of this research, we are now a step closer to produce optimum catalysts in which the active phase forms only surface monolayers. In addition, the nanoalloy exhibits high index facet surfaces with {211} and {321} families that are highly open-structure surfaces and are interesting for the catalytic applications.

Highly Monodisperse Multiple Twinned AuCu/Pt Trimetallic Nanoparticles with High Index Surfaces

PubMed Central

Khanal, Subarna; Bhattarai, Nabraj; McMaster, David; Bahena, Daniel; Velazquez-Salazar, J. Jesus

2014-01-01

Trimetallic nanoparticles present different properties than their mono- and bi-metallic counterparts, opening a wide range of possibilities for diverse potential applications with the notion to study possible morphology, atomic ordering, reduce precious metal consumption and many others. In this paper, we are presenting a comprehensive experimental study on AuCu/Pt trimetallic nanoparticles with an average diameter 15 ± 1.0 nm, synthesized in one-pot synthesis method and characterized by Cs-corrected scanning transmission electron microscopy technique that allowed us to probe the structure at the atomic level resolution. A new way to control the nanoparticle morphology by the presence of third metal (Pt) is also discussed by the overgrowth of Pt on as prepared AuCu core by Frank–van der Merwe (FM) layer-by-layer and Stranski–Krastanov (SK) island-on-wetting-layer growth modes. With the application of this research, we are now a step closer to produce optimum catalysts in which the active phase forms only surface monolayers. In addition, the nanoalloy presents high index facet surfaces with {211} and {321} families, that are highly open-structure surfaces and are interesting for the catalytic applications. PMID:24975090

Surface modifications of crystal-ion-sliced LiNbO3 thin films by low energy ion irradiations

NASA Astrophysics Data System (ADS)

Bai, Xiaoyuan; Shuai, Yao; Gong, Chaoguan; Wu, Chuangui; Luo, Wenbo; Böttger, Roman; Zhou, Shengqiang; Zhang, Wanli

2018-03-01

Single crystalline 128°Y-cut LiNbO3 thin films with a thickness of 670 nm are fabricated onto Si substrates by means of crystal ion slicing (CIS) technique, adhesive wafer bonding using BCB as the medium layer to alleviate the large thermal coefficient mismatch between LiNbO3 and Si, and the X-ray diffraction pattern indicates the exfoliated thin films have good crystalline quality. The LiNbO3 thin films are modified by low energy Ar+ irradiation, and the surface roughness of the films is decreased from 8.7 nm to 3.4 nm. The sputtering of the Ar+ irradiation is studied by scanning electron microscope, atomic force microscope and X-ray photoelectron spectroscopy, and the results show that an amorphous layer exists at the surface of the exfoliated film, which can be quickly removed by Ar+ irradiation. A two-stage etching mechanism by Ar+ irradiation is demonstrated, which not only establishes a new non-contact surface polishing method for the CIS-fabricated single crystalline thin films, but also is potentially useful to remove the residue damage layer produced during the CIS process.

Pulsed laser diffusion of thin hole-barrier contacts in high purity germanium for gamma radiation detectors

NASA Astrophysics Data System (ADS)

Maggioni, G.; Carturan, S.; Raniero, W.; Riccetto, S.; Sgarbossa, F.; Boldrini, V.; Milazzo, R.; Napoli, D. R.; Scarpa, D.; Andrighetto, A.; Napolitani, E.; De Salvador, D.

2018-03-01

A new method for the formation of hole-barrier contacts in high purity germanium (HPGe) is described, which consists in the sputter deposition of a Sb film on HPGe, followed by Sb diffusion produced through laser annealing of the Ge surface in the melting regime. This process gives rise to a very thin ( ≤ 100 nm) n-doped layer, as determined by SIMS measurement, while preserving the defect-free morphology of HPGe surface. A small prototype of gamma ray detector with a Sb laser-diffused contact was produced and characterized, showing low leakage currents and good spectroscopy data with different gamma ray sources.

Earth-based remote sensing of planetary surfaces and atmospheres at radio wavelengths

NASA Technical Reports Server (NTRS)

Dickel, J. R.

1982-01-01

Two reasons for remote sensing from the Earth are given: (1) space exploration, particularly below the surfaces or underneath cloud layers, is limited to only a very few planets; and (2) a program of regular monitoring, currently impractical with a limited number of space probes, is required. Reflected solar and nonthermal radiation are discussed. Relativistic electrons, trapped in large magnetospheres on Saturn and Jupiter, are discussed. These electrons produce synchrotron radiation and also interact with the ionosphere to produce bursts of low frequency emission. Because most objects are black-bodies, continuum radiometry is emphasized. Spectroscopic techniques and the measurement of nonthermal emission are also discussed.

Direct Radiative Impacts of Central American Biomass Burning Smoke Aerosols: Analysis from a Coupled Aerosol-Radiation-Meteorology Model RAMS-AROMA

NASA Astrophysics Data System (ADS)

Wang, J.; Christopher, S. A.; Nair, U. S.; Reid, J. S.; Prins, E. M.

2005-12-01

Considerable efforts including various field experiments have been carried out in the last decade for studying the regional climatic impact of smoke aerosols produced by biomass burning activities in Africa and South America. In contrast, only few investigations have been conducted for Central American Biomass Burning (CABB) region. Using a coupled aerosol-radiation-meteorology model called RAMS-AROMA together with various ground-based observations, we present a comprehensive analysis of the smoke direct radiative impacts on the surface energy budget, boundary layer evolution, and e precipitation process during the CABB events in Spring 2003. Quantitative estimates are also made regarding the transboundary carbon mass to the U.S. in the form of smoke particles. Buult upon the Regional Atmospheric Modeling System (RAMS) mesoscale model, the RAMS AROMA has several features including Assimilation and Radiation Online Modeling of Aerosols (AROMA) algorithms. The model simulates smoke transport by using hourly smoke emission inventory from the Fire Locating and Modeling of Burning Emissions (FLAMBE) geostationary satellite database. It explicitly considers the smoke effects on the radiative transfer at each model time step and model grid, thereby coupling the dynamical processes and aerosol transport. Comparison with ground-based observation show that the simulation realistically captured the smoke transport timeline and distribution from daily to hourly scales. The effects of smoke radiative extinction on the decrease of 2m air temperature (2mT), diurnal temperature range (DTR), and boundary layer height over the land surface are also quantified. Warming due to smoke absorption of solar radiation can be found in the lower troposphere over the ocean, but not near the underlying land surface. The increase of boundary layer stability produces a positive feedback where more smoke particles are trapped in the lower boundary layer. These changes in temperature, surface energy budget and the atmospheric lapse rate have important ramification for the simulation of precipitations.

In vitro biocompatibility of magnesium-incorporated submicro-porous titanium oxide surface produced by hydrothermal treatment

NASA Astrophysics Data System (ADS)

Park, Jin-Woo; Kim, Youn-Jeong; Jang, Je-Hee; An, Chang-Hyeon

2010-11-01

This study investigated the surface characteristics and in vitro biocompatibility of titanium (Ti) oxide surface incorporating magnesium ions (Mg), produced by hydrothermal treatment using an alkaline Mg-containing solution, for future biomedical applications. The surface characteristics were evaluated by scanning electron microscopy, thin-film X-ray diffractometry, X-ray photoelectron spectroscopy, inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and optical profilometry. Mouse calvaria-derived osteoblastic cell (MC3T3-E1) attachment, spreading, proliferation, alkaline phosphatase (ALP) activity, and osteoblastic gene expression on Mg-containing surfaces were compared with untreated Ti surfaces. Hydrothermal treatment resulted in Mg-incorporated Ti oxide layer with submicro-porous surface structures approximately 2 μm in thickness. ICP-AES analysis revealed Mg ions release from treated surfaces into the solution. The Mg-incorporated surface displayed significantly increased cellular attachment and ALP activity compared with untreated surface ( p < 0.05), and supported better cell spreading. Real-time polymerase chain reaction analysis showed notably higher mRNA expression of the osteoblast transcription factor genes (Dlx5, Runx2) and the osteoblast phenotype genes (ALP, bone sialoprotein and osteocalcin) in cells grown on the Mg-incorporated surfaces than untreated surfaces. These results demonstrate that the Mg-incorporated submicro-porous Ti oxide surface produced by hydrothermal treatment may improve implant osseointegration by enhancing the attachment, spreading and differentiation of osteoblastic cells.

Barite, BIFs and bugs: evidence for the evolution of the Earth's early hydrosphere

NASA Astrophysics Data System (ADS)

Huston, David L.; Logan, Graham A.

2004-03-01

The presence of relatively abundant bedded sulfate deposits before 3.2 Ga and after 1.8 Ga, the peak in iron formation abundance between 3.2 and 1.8 Ga, and the aqueous geochemistry of sulfur and iron together suggest that the redox state and the abundances of sulfur and iron in the hydrosphere varied widely during the Archean and Proterozoic. We propose a layered hydrosphere prior to 3.2 Ga in which sulfate produced by atmospheric photolytic reactions was enriched in an upper layer, whereas the underlying layer was reduced and sulfur-poor. Between 3.2 and 2.4 Ga, sulfate reduction removed sulfate from the upper layer, producing broadly uniform, reduced, sulfur-poor and iron-rich oceans. As a result of increasing atmospheric oxygenation around 2.4 Ga, the flux of sulfate into the hydrosphere by oxidative weathering was greatly enhanced, producing layered oceans, with sulfate-enriched, iron-poor surface waters and reduced, sulfur-poor and iron-rich bottom waters. The rate at which this process proceeded varied between basins depending on the size and local environment of the basin. By 1.8 Ga, the hydrosphere was relatively sulfate-rich and iron-poor throughout. Variations in sulfur and iron abundances suggest that the redox state of the oceans was buffered by iron before 2.4 Ga and by sulfur after 1.8 Ga.

Metal-assisted exfoliation (MAE): green process for transferring graphene to flexible substrates and templating of sub-nanometer plasmonic gaps (Presentation Recording)

NASA Astrophysics Data System (ADS)

Zaretski, Aliaksandr V.; Marin, Brandon C.; Moetazedi, Herad; Dill, Tyler J.; Jibril, Liban; Kong, Casey; Tao, Andrea R.; Lipomi, Darren J.

2015-09-01

This paper describes a new technique, termed "metal-assisted exfoliation," for the scalable transfer of graphene from catalytic copper foils to flexible polymeric supports. The process is amenable to roll-to-roll manufacturing, and the copper substrate can be recycled. We then demonstrate the use of single-layer graphene as a template for the formation of sub-nanometer plasmonic gaps using a scalable fabrication process called "nanoskiving." These gaps are formed between parallel gold nanowires in a process that first produces three-layer thin films with the architecture gold/single-layer graphene/gold, and then sections the composite films with an ultramicrotome. The structures produced can be treated as two gold nanowires separated along their entire lengths by an atomically thin graphene nanoribbon. Oxygen plasma etches the sandwiched graphene to a finite depth; this action produces a sub-nanometer gap near the top surface of the junction between the wires that is capable of supporting highly confined optical fields. The confinement of light is confirmed by surface-enhanced Raman spectroscopy measurements, which indicate that the enhancement of the electric field arises from the junction between the gold nanowires. These experiments demonstrate nanoskiving as a unique and easy-to-implement fabrication technique that is capable of forming sub-nanometer plasmonic gaps between parallel metallic nanostructures over long, macroscopic distances. These structures could be valuable for fundamental investigations as well as applications in plasmonics and molecular electronics.

Raman spectroscopic studies of the interaction of oxalic acid and sodium oxalate used as corrosion inhibitors with copper

NASA Astrophysics Data System (ADS)

Jeziorowski, H.; Moser, B.

1985-09-01

The Raman spectra of the liquid-solid interface recorded in situ show the formation of a salt complex of the inhibitor molecules and the copper ions. This suggests that this chemisorbed surface species produces the protective layer.

Observations of near-surface fresh layers during SPURS-2

NASA Astrophysics Data System (ADS)

Drushka, Kyla; E Asher, William; Thompson, Elizabeth; Jessup, Andrew T.; Clark, Dan

2017-04-01

One of the primary objectives of the ongoing SPURS-2 program is to understand the fate of rainfall deposited on the sea surface. Rain produces stable near-surface fresh layers that persist for O(1-10) hours. The depth, strength, and lifetime of surface fresh layers are known to be related to the local rain and wind conditions, but available observational data are too sparse to allow definitive quantification of cause-and-effect relationships. In this paper, the formation and evolution of rain-formed fresh layers are examined using observations of near-surface salinity made during the 2016 SPURS-2 field experiment, which took place in the Intertropical Convergence Zone of the eastern tropical Pacific Ocean in August-September 2016. During 2016 SPURS-2, over 30 rain events were captured with the Surface Salinity Profiler (SSP), a towed platform that measures salinity and temperature at five discrete depths in the upper meter of the ocean. Differences in salinity measured by the SSP at depths of 0.02 m and at 1 m are correlated with local meteorological conditions. The field results show that the salinity difference increases linearly with rain rate, a result that is consistent with calculations done with a one-dimensional ocean turbulence model. The field data also demonstrate that there is an inverse correlation between wind speed and the vertical salinity difference, which is also consistent with numerical models. The implications of these results are discussed in the context of satellite salinity observations and the representation of rainfall events in climate models.

Ultramorphology of the root surface subsequent to hand-ultrasonic simultaneous instrumentation during non-surgical periodontal treatments. An in vitro study

PubMed Central

D. ASPRIELLO, Simone; PIEMONTESE, Matteo; LEVRINI, Luca; SAURO, Salvatore

2011-01-01

Objective The purpose of this study was to investigate the ultramorphology of the root surfaces induced by mechanical instrumentation performed using conventional curettes or piezoelectric scalers when used single-handedly or with a combined technique. Material and Methods Thirty single-rooted teeth were selected and divided into 3 groups: Group A, instrumentation with curettes; Group B instrumentation with titanium nitride coated periodontal tip mounted in a piezoelectric handpiece; Group C, combined technique with curette/ultrasonic piezoelectric instrumentation. The specimens were processed and analyzed using confocal and scanning electron microscopy. Differences between the different groups of instrumentation were determined using Pearson’s χ 2 with significance predetermined at α=0.001. Results Periodontal scaling and root planing performed with curettes, ultrasonic or combined instrumentation induced several morphological changes on the root surface. The curettes produced a compact and thick multilayered smear layer, while the morphology of the root surfaces after ultrasonic scaler treatment appeared irregular with few grooves and a thin smear layer. The combination of curette/ultrasonic instrumentation showed exposed root dentin tubules with a surface morphology characterized by the presence of very few grooves and slender remnants of smear layer which only partially covered the root dentin. In some cases, it was also possible to observe areas with exposed collagen fibrils. Conclusion The curette-ultrasonic simultaneous instrumentation may combine the beneficial effects of each instrument in a single technique creating a root surface relatively free from the physical barrier of smear layer and dentin tubules orifices partial occlusion. PMID:21437474

Porous TiO₂ surface formed on nickel-titanium alloy by plasma electrolytic oxidation: a prospective polymer-free reservoir for drug eluting stent applications.

PubMed

Huan, Zhiguang; Fratila-Apachitei, Lidy E; Apachitei, Iulian; Duszczyk, Jurek

2013-07-01

In this study, a porous oxide layer was formed on the surface of nickel-titanium alloy (NiTi) by plasma electrolytic oxidation (PEO) with the aim to produce a polymer-free drug carrier for drug eluting stent (DES) applications. The oxidation was performed galvanostatically in concentrated phosphoric acid electrolyte at low temperature. It was found that the response of NiTi substrate during the PEO process was different from that of bulk Ti, since the presence of large amount of Ni delayed the initial formation of a compact oxide layer that is essential for the PEO to take place. Under optimized PEO conditions, the resultant surface showed porosity, pore density and oxide layer thickness of 14.11%, 2.40 × 10⁵ pores/mm² and 0.8 μm, respectively. It was additionally noted that surface roughness after PEO did not significantly increase as compared with that of original NiTi substrate and the EDS analyses revealed a decrease in Ni/Ti ratio on the surface after PEO. The cross-section morphology showed no discontinuity between the PEO layer and the NiTi substrate. Furthermore, wettability and surface free energy of the NiTi substrate increased significantly after PEO treatment. The PEO process could be successfully translated to NiTi stent configuration proving for the first time its feasibility for such a medical device and offering potential for development of alternative, polymer-free drug carriers for NiTi DES. Copyright © 2013 Wiley Periodicals, Inc.