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Sample records for oxide substrates struktura

  1. Substrate-Sensitive Graphene Oxidation.

    PubMed

    Zhang, Zhuhua; Yin, Jun; Liu, Xiaofei; Li, Jidong; Zhang, Jiahuan; Guo, Wanlin

    2016-03-01

    The inertness of graphene toward reaction with ambient molecules is essential for realizing durable devices with stable performance. Many device applications require graphene to contact with substrates, but whose impact on the chemical property of graphene has been largely overlooked. Here, we combine comprehensive first-principles analyses with experiments to show that graphene oxidation is highly sensitive to substrates. Graphene remains inert on SiO2 and hexagonal boron nitride but becomes increasingly weak against oxidation on metal substrates because of enhanced charge transfer and chemical interaction between them. In particular, Ni and Co substrates lead to spontaneous oxidation of graphene, while a Cu substrate maximally promotes the oxygen diffusion on graphene, with an estimated diffusivity 13 orders of magnitude higher than that on freestanding graphene. Bilayer graphene is revealed to have high oxidation resistance independent of substrate and thus is a better choice for high-performance nanoelectronics. Our findings should be extendable to a wide spectrum of chemical functionalizations of two-dimensional materials mediated by substrates. PMID:26884318

  2. High quality oxide films on substrates

    DOEpatents

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

    1994-01-01

    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.

  3. High quality oxide films on substrates

    DOEpatents

    Ruckman, M.W.; Strongin, M.; Gao, Y.L.

    1994-02-01

    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.

  4. Silica substrate or portion formed from oxidation of monocrystalline silicon

    DOEpatents

    Matzke, Carolyn M.; Rieger, Dennis J.; Ellis, Robert V.

    2003-07-15

    A method is disclosed for forming an inclusion-free silica substrate using a monocrystalline silicon substrate as the starting material and oxidizing the silicon substrate to convert it entirely to silica. The oxidation process is performed from both major surfaces of the silicon substrate using a conventional high-pressure oxidation system. The resulting product is an amorphous silica substrate which is expected to have superior etching characteristics for microfabrication than conventional fused silica substrates. The present invention can also be used to convert only a portion of a monocrystalline silicon substrate to silica by masking the silicon substrate and locally thinning a portion the silicon substrate prior to converting the silicon portion entirely to silica. In this case, the silica formed by oxidizing the thinned portion of the silicon substrate can be used, for example, as a window to provide optical access through the silicon substrate.

  5. 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.

  6. 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.

  7. Single crystal complex oxide on flexible substrate

    NASA Astrophysics Data System (ADS)

    Bakaul, Saidur; Serrao, Claudy; Lee, Oukjae; Salahuddin, Sayeef

    Flexible ferroelectrics are needed for various applications such as biocompatible energy harvesting and flexible memory. In this sector, most of the current research is focused on organic piezoelectric materials which have advantage of flexibility but suffers severely from poor energy conversion and generation efficiency. On the contrary, owing to very high electromechanical coupling factor (representing energy conversion efficiency) complex oxides are the best choices as energy harvesting and transduction elements, especially for transforming mechanical energies into electronic energy. Still their usage in energy harvesting is very limited mainly due to the stringent growth conditions of single crystals, high temperature needed for crystallization and lack of flexibility and stretchability. We have shown that single crystal Pb0.8Zr0.2TiO3 can be epitaxially transferred on flexible plastic substrate. The transferred PZT shows 70 uC/cm2 remnant polarization and dielectric constant over 100 even when it is bent. These results suggest the possibility of single crystal complex oxide devices on flexible platform.

  8. Alkoxysilane adsorption on metal oxide substrates

    NASA Technical Reports Server (NTRS)

    Ramsier, R. D.; Zhuang, G. R.; Henriksen, P. N.

    1989-01-01

    Reflection-absorption infrared and inelastic electron tunneling spectroscopies have been used to study adsorption of liquid phase mono-, di-, and trialkoxysilanes on evaporated Al and Cu substrates. Spectral evidence shows that substrate properties influence the chemical and physical nature of trialkoxysilane films and that silane functionality plays a role in molecular orientation. Results show that dialkoxysilane films contain structural gradients, with adsorption at the monomolecular level influenced by surface morphology, and with organofunctionality and dosing procedure affecting the formation of thicker films. Evidence is presented that monoalkoxysilanes react with alumina surfaces, and a broad, multipeaked band from 1600 to 1900/cm has been interpreted as characteristic of the silylated AlO(x)Pb interface.

  9. Interfacial Shear Strength of Oxide Scale and SS 441 Substrate

    SciTech Connect

    Liu, Wenning N.; Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2011-05-01

    Recent developments on decreasing the operating temperature for Solid Oxide Fuel Cells (SOFCs) have enabled the use of high temperature ferritic alloys as interconnect materials. Oxide scale will inevitably grow on the ferritic interconnects in a high temperature oxidation environment of SOFCs. The growth of the oxide scale induces growth stresses in the scale layer and on the scale/substrate interface. These growth stresses combined with the thermal stresses induced upon stacking cooling by the thermal expansion coefficient mismatch between the oxide scale and the substrate may lead to scale delamination/buckling and eventual spallation, which may lead to serious cell performance degradation. Hence the interfacial adhesion strength between the oxide scale and the substrate is crucial to the reliability and durability of the metallic interconnect in SOFC operating environments. In this paper, we applied an integrated experimental/modeling methodology to quantify the interfacial adhesion strength between the oxide scale and the SS 441 metallic interconnect. The predicted interfacial strength is discussed in details.

  10. Effect of Substrate Thickness on Oxide Scale Spallation for Solid Oxide Fuel Cells

    SciTech Connect

    Liu, Wenning N.; Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2011-07-01

    In this paper, the effect of the ferritic substrate's thickness on the delamination/spallation of the oxide scale was investigated experimentally and numerically. At the high-temperature oxidation environment of solid oxide fuel cells (SOFCs), a combination of growth stress with thermal stresses may lead to scale delamination/buckling and eventual spallation during SOFC stack cooling, even leading to serious degradation of cell performance. The growth stress is induced by the growth of the oxide scale on the scale/substrate interface, and thermal stress is induced by a mismatch of the coefficient of thermal expansion between the oxide scale and the substrate. The numerical results show that the interfacial shear stresses, which are the driving force of scale delamination between the oxide scale and the ferritic substrate, increase with the growth of the oxide scale and also with the thickness of the ferritic substrate; i.e., the thick ferritic substrate can easily lead to scale delamination and spallation. Experimental observation confirmed the predicted results of the delamination and spallation of the oxide scale on the ferritic substrate.

  11. Gold coated zinc oxide nanonecklaces as a SERS substrate.

    PubMed

    He, Lili; Shi, Jian; Sun, Xin; Lin, Mengshi; Yu, Ping; Li, Hao

    2011-04-01

    Faceted zinc oxide nanonecklace (ZnO NN) arrays were grown on r-plane sapphires along one direction (ZnO [0001] II sapphire [10-11] and ZnO (-12-10) II sapphire (01-12)) using chemical vapor deposition. After coated with 45 nm gold films and annealed at 250 degrees C for 30 seconds, the coated ZnO NNs exhibit satisfactory and stable surface enhanced Raman scattering (SERS) effects when tested with melamine and other chemicals. The limit of detection of melamine is 10(-5) mol/L and the analytical enhancement factor is 10(4), which is competitive to a commercial substrate. This study indicates that gold coated ZnO NN substrates have a great potential as SERS-active substrates in rapid detection of trace amount food contaminants such as melamine and other chemicals. PMID:21776731

  12. Epitaxial Zinc Oxide Semiconductor Film deposited on Gallium Nitride Substrate

    NASA Astrophysics Data System (ADS)

    McMaster, Michael; Oder, Tom

    2011-04-01

    Zinc oxide (ZnO) is a wide bandgap semiconductor which is very promising for making efficient electronic and optical devices. The goal of this research was to produce high quality ZnO film on gallium nitride (GaN) substrate by optimizing the substrate temperature. The GaN substrates were chemically cleaned and mounted on a ceramic heater and loaded into a vacuum deposition chamber that was pumped down to a base pressure of 3 x 10-7 Torr. The film deposition was preceded by a 30 minute thermal desorption carried in vacuum at 500 ^oC. The ZnO thin film was then sputter-deposited using an O2/Ar gas mixture onto GaN substrates heated at temperatures varying from 20 ^oC to 500 ^oC. Post-deposition annealing was done in a rapid thermal processor at 900 ^oC for 5 min in an ultrapure N2 ambient to improve the crystal quality of the films. The films were then optically characterized using photoluminescence (PL) measurement with a UV laser excitation. Our measurements reveal that ZnO films deposited on GaN substrate held at 200 ^oC gave the best film with the highest luminous intensity, with a peak energy of 3.28 eV and a full width half maximum of 87.4 nm. Results from low temperature (10 K) PL measurements and from x-ray diffraction will also be presented.

  13. Substrate Oxidation by Indoleamine 2,3-Dioxygenase

    PubMed Central

    Booth, Elizabeth S.; Basran, Jaswir; Lee, Michael; Handa, Sandeep; Raven, Emma L.

    2015-01-01

    The kynurenine pathway is the major route of l-tryptophan (l-Trp) catabolism in biology, leading ultimately to the formation of NAD+. The initial and rate-limiting step of the kynurenine pathway involves oxidation of l-Trp to N-formylkynurenine. This is an O2-dependent process and catalyzed by indoleamine 2,3-dioxygenase and tryptophan 2,3-dioxygenase. More than 60 years after these dioxygenase enzymes were first isolated (Kotake, Y., and Masayama, I. (1936) Z. Physiol. Chem. 243, 237–244), the mechanism of the reaction is not established. We examined the mechanism of substrate oxidation for a series of substituted tryptophan analogues by indoleamine 2,3-dioxygenase. We observed formation of a transient intermediate, assigned as a Compound II (ferryl) species, during oxidation of l-Trp, 1-methyl-l-Trp, and a number of other substrate analogues. The data are consistent with a common reaction mechanism for indoleamine 2,3-dioxygenase-catalyzed oxidation of tryptophan and other tryptophan analogues. PMID:26511316

  14. Electrical and mechanical properties of graphene oxide on flexible substrate

    NASA Astrophysics Data System (ADS)

    Kang, Shao-Hui; Fang, Te-Hua; Hong, Zheng-Han

    2013-12-01

    Graphene oxide (GO) was deposited via the electrophoretic deposition (EPD) method to lower the oxygen concentration of graphene sheets for large-scale production. In addition, the direct synthesis of large-scale GO films using transfer processes on a polydimethylsiloxane (PDMS) substrate was conducted. The thickness of the GO films was controlled to adjust the optical, electrical, and mechanical properties. The Young's modulus values of films with thicknesses of 100-200 nm were 324-529 GPa. Moreover, the GO films exhibited excellent conductivity, with a sheet resistance of 276-2024 Ω/sq at 23-77% transparency. Experiments show that transfer processes for flexible substrates can produce high-quality cost-effective transparent conductive films.

  15. Oxidized SWCNT chemically attached to a modified copper substrate

    NASA Astrophysics Data System (ADS)

    Hernandez, Dionne; Cabrera, Carlos R.; Mendez, Laura; Diaz-Serrano, Madeline; Vega, Omar; Weiner, Brad R.; Rosa, Luis G.

    2015-08-01

    Oxidized single-wall carbon nanotubes were chemically attached to a modified copper substrate by means of a 4-aminothiophenol (4-ATP) self-assembly monolayer (SAM). This bottom up approach offers a low cost route to attach carbon nanotubes by using a condensation reaction. Here, the exposed amine from the 4-ATP SAM reacts with the carboxylic group (COOH) on the CNT. The reaction was followed using ATR-FTIR and the surface was characterized using SEM, XPS, and Raman. The analytical techniques used on this study suggest that the condensation reaction employed using a carbodiimide such as 1-Ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (EDC) produced SWCNT attached to the copper substrate.

  16. Two Oxidation Sites for Low Redox Potential Substrates

    PubMed Central

    Morales, María; Mate, María J.; Romero, Antonio; Martínez, María Jesús; Martínez, Ángel T.; Ruiz-Dueñas, Francisco J.

    2012-01-01

    Versatile peroxidase shares with manganese peroxidase and lignin peroxidase the ability to oxidize Mn2+ and high redox potential aromatic compounds, respectively. Moreover, it is also able to oxidize phenols (and low redox potential dyes) at two catalytic sites, as shown by biphasic kinetics. A high efficiency site (with 2,6-dimethoxyphenol and p-hydroquinone catalytic efficiencies of ∼70 and ∼700 s−1 mm−1, respectively) was localized at the same exposed Trp-164 responsible for high redox potential substrate oxidation (as shown by activity loss in the W164S variant). The second site, characterized by low catalytic efficiency (∼3 and ∼50 s−1 mm−1 for 2,6-dimethoxyphenol and p-hydroquinone, respectively) was localized at the main heme access channel. Steady-state and transient-state kinetics for oxidation of phenols and dyes at the latter site were improved when side chains of residues forming the heme channel edge were removed in single and multiple variants. Among them, the E140G/K176G, E140G/P141G/K176G, and E140G/W164S/K176G variants attained catalytic efficiencies for oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) at the heme channel similar to those of the exposed tryptophan site. The heme channel enlargement shown by x-ray diffraction of the E140G, P141G, K176G, and E140G/K176G variants would allow a better substrate accommodation near the heme, as revealed by the up to 26-fold lower Km values (compared with native VP). The resulting interactions were shown by the x-ray structure of the E140G-guaiacol complex, which includes two H-bonds of the substrate with Arg-43 and Pro-139 in the distal heme pocket (at the end of the heme channel) and several hydrophobic interactions with other residues and the heme cofactor. PMID:23071108

  17. Flexible Metal Oxide/Graphene Oxide Hybrid Neuromorphic Transistors on Flexible Conducting Graphene Substrates.

    PubMed

    Wan, Chang Jin; Liu, Yang Hui; Feng, Ping; Wang, Wei; Zhu, Li Qiang; Liu, Zhao Ping; Shi, Yi; Wan, Qing

    2016-07-01

    Flexible metal oxide/graphene oxide hybrid multi-gate neuromorphic transistors are fabricated on flexible conducting graphene substrates. Dendritic integrations in both spatial and temporal modes are emulated, and spatiotemporal correlated logics are obtained. A proof-of-principle visual system model for emulating Lobula Giant Motion Detector neuron is also investigated. The results are of great significance for flexible sensors and neuromorphic cognitive systems. PMID:27159546

  18. Charge inhomogeneity determines oxidative reactivity of graphene on substrates.

    PubMed

    Yamamoto, Mahito; Einstein, Theodore L; Fuhrer, Michael S; Cullen, William G

    2012-09-25

    Single-layer graphene (SLG) supported on SiO(2) shows anomalously large chemical reactivity compared to thicker graphene, with charge inhomogeneity-induced potential fluctuations or topographic corrugations proposed as the cause. Here we systematically probe the oxidative reactivity of graphene supported on substrates with different surface roughnesses and charged impurity densities: hexagonal boron nitride (hBN), mica, thermally grown SiO(2) on Si, and SiO(2) nanoparticle thin films. SLG on low charge trap density hBN is not etched and shows little doping after oxygen treatment at temperatures up to 550 °C, in sharp contrast with oxidative etching under similar conditions of graphene on high charge trap density SiO(2) and mica. Furthermore, bilayer graphene shows reduced reactivity compared to SLG regardless of its substrate-induced roughness. Together the observations indicate that graphene's reactivity is predominantly controlled by charge inhomogeneity-induced potential fluctuations rather than surface roughness. PMID:22917254

  19. Atomic layer deposition of hafnium oxide on germanium substrates

    NASA Astrophysics Data System (ADS)

    Delabie, Annelies; Puurunen, Riikka L.; Brijs, Bert; Caymax, Matty; Conard, Thierry; Onsia, Bart; Richard, Olivier; Vandervorst, Wilfried; Zhao, Chao; Heyns, Marc M.; Meuris, Marc; Viitanen, Minna M.; Brongersma, Hidde H.; de Ridder, Marco; Goncharova, Lyudmila V.; Garfunkel, Eric; Gustafsson, Torgny; Tsai, Wilman

    2005-03-01

    Germanium combined with high-κ dielectrics has recently been put forth by the semiconductor industry as potential replacement for planar silicon transistors, which are unlikely to accommodate the severe scaling requirements for sub-45-nm generations. Therefore, we have studied the atomic layer deposition (ALD) of HfO2 high-κ dielectric layers on HF-cleaned Ge substrates. In this contribution, we describe the HfO2 growth characteristics, HfO2 bulk properties, and Ge interface. Substrate-enhanced HfO2 growth occurs: the growth per cycle is larger in the first reaction cycles than the steady growth per cycle of 0.04nm. The enhanced growth goes together with island growth, indicating that more than a monolayer coverage of HfO2 is required for a closed film. A closed HfO2 layer is achieved after depositing 4-5HfO2 monolayers, corresponding to about 25 ALD reaction cycles. Cross-sectional transmission electron microscopy images show that HfO2 layers thinner than 3nm are amorphous as deposited, while local epitaxial crystallization has occurred in thicker HfO2 films. Other HfO2 bulk properties are similar for Ge and Si substrates. According to this physical characterization study, HfO2 can be used in Ge-based devices as a gate oxide with physical thickness scaled down to 1.6nm.

  20. Oxide perovskite crystals for HTSC film substrates microwave applications

    NASA Technical Reports Server (NTRS)

    Bhalla, A. S.; Guo, Ruyan

    1995-01-01

    The research focused upon generating new substrate materials for the deposition of superconducting yttrium barium cuprate (YBCO) has yielded several new hosts in complex perovskites, modified perovskites, and other structure families. New substrate candidates such as Sr(Al(1/2)Ta(1/2))O3 and Sr(Al(1/2)Nb(1/2))O3, Ba(Mg(1/3)Ta(2/3))O3 in complex oxide perovskite structure family and their solid solutions with ternary perovskite LaAlO3 and NdGaO3 are reported. Conventional ceramic processing techniques were used to fabricate dense ceramic samples. A laser heated molten zone growth system was utilized for the test-growth of these candidate materials in single crystal fiber form to determine crystallographic structure, melting point, thermal, and dielectric properties as well as to make positive identification of twin free systems. Some of those candidate materials present an excellent combination of properties suitable for microwave HTSC substrate applications.

  1. Oxidation stress evolution and relaxation of oxide film/metal substrate system

    NASA Astrophysics Data System (ADS)

    Dong, Xuelin; Feng, Xue; Hwang, Keh-Chih

    2012-07-01

    Stresses in the oxide film/metal substrate system are crucial to the reliability of the system at high temperature. Two models for predicting the stress evolution during isothermal oxidation are proposed. The deformation of the system is depicted by the curvature for single surface oxidation. The creep strain of the oxide and metal, and the lateral growth strain of the oxide are considered. The proposed models are compared with the experimental results in literature, which demonstrates that the elastic model only considering for elastic strain gives an overestimated stress in magnitude, but the creep model is consistent with the experimental data and captures the stress relaxation phenomenon during oxidation. The effects of the parameter for the lateral growth strain rate are also analyzed.

  2. Lateral solid-phase epitaxy of oxide thin films on glass substrate seeded with oxide nanosheets.

    PubMed

    Taira, Kenji; Hirose, Yasushi; Nakao, Shoichiro; Yamada, Naoomi; Kogure, Toshihiro; Shibata, Tatsuo; Sasaki, Takayoshi; Hasegawa, Tetsuya

    2014-06-24

    We developed a technique to fabricate oxide thin films with uniaxially controlled crystallographic orientation and lateral size of more than micrometers on amorphous substrates. This technique is lateral solid-phase epitaxy, where epitaxial crystallization of amorphous precursor is seeded with ultrathin oxide nanosheets sparsely (≈10% coverage) deposited on the substrate. Transparent conducting Nb-doped anatase TiO2 thin films were fabricated on glass substrates by this technique. Perfect (001) orientation and large grains with lateral sizes up to 10 μm were confirmed by X-ray diffraction, atomic force microscopy, and electron beam backscattering diffraction measurements. As a consequence of these features, the obtained film exhibited excellent electrical transport properties comparable to those of epitaxial thin films on single-crystalline substrates. This technique is a versatile method for fabricating high-quality oxide thin films other than anatase TiO2 and would increase the possible applications of oxide-based thin film devices. PMID:24867286

  3. Polycrystalline ferroelectric or multiferroic oxide articles on biaxially textured substrates and methods for making same

    SciTech Connect

    Goyal, Amit; Shin, Junsoo

    2015-03-31

    A polycrystalline ferroelectric and/or multiferroic oxide article includes a substrate having a biaxially textured surface; at least one biaxially textured buffer layer supported by the substrate; and a biaxially textured ferroelectric or multiferroic oxide layer supported by the buffer layer. Methods for making polycrystalline ferroelectric and/or multiferroic oxide articles are also disclosed.

  4. Decoding the Substrate Supply to Human Neuronal Nitric Oxide Synthase

    PubMed Central

    Habermeier, Alice; Closs, Ellen I.

    2013-01-01

    Nitric oxide, produced by the neuronal nitric oxide synthase (nNOS) from L-arginine is an important second messenger molecule in the central nervous system: It influences the synthesis and release of neurotransmitters and plays an important role in long-term potentiation, long-term depression and neuroendocrine secretion. However, under certain pathological conditions such as Alzheimer’s or Parkinson’s disease, stroke and multiple sclerosis, excessive NO production can lead to tissue damage. It is thus desirable to control NO production in these situations. So far, little is known about the substrate supply to human nNOS as a determinant of its activity. Measuring bioactive NO via cGMP formation in reporter cells, we demonstrate here that nNOS in both, human A673 neuroepithelioma and TGW-nu-I neuroblastoma cells can be fast and efficiently nourished by extracellular arginine that enters the cells via membrane transporters (pool I that is freely exchangeable with the extracellular space). When this pool was depleted, NO synthesis was partially sustained by intracellular arginine sources not freely exchangeable with the extracellular space (pool II). Protein breakdown made up by far the largest part of pool II in both cell types. In contrast, citrulline to arginine conversion maintained NO synthesis only in TGW-nu-I neuroblastoma, but not A673 neuroepithelioma cells. Histidine mimicked the effect of protease inhibitors causing an almost complete nNOS inhibition in cells incubated additionally in lysine that depletes the exchangeable arginine pool. Our results identify new ways to modulate nNOS activity by modifying its substrate supply. PMID:23874440

  5. Efficient Direct Reduction of Graphene Oxide by Silicon Substrate.

    PubMed

    Lee, Su Chan; Some, Surajit; Kim, Sung Wook; Kim, Sun Jun; Seo, Jungmok; Lee, Jooho; Lee, Taeyoon; Ahn, Jong-Hyun; Choi, Heon-Jin; Jun, Seong Chan

    2015-01-01

    Graphene has been studied for various applications due to its excellent properties. Graphene film fabrication from solutions of graphene oxide (GO) have attracted considerable attention because these procedures are suitable for mass production. GO, however, is an insulator, and therefore a reduction process is required to make the GO film conductive. These reduction procedures require chemical reducing agents or high temperature annealing. Herein, we report a novel direct and simple reduction procedure of GO by silicon, which is the most widely used material in the electronics industry. In this study, we also used silicon nanosheets (SiNSs) as reducing agents for GO. The reducing effect of silicon was confirmed by various characterization methods. Furthermore, the silicon wafer was also used as a reducing template to create a reduced GO (rGO) film on a silicon substrate. By this process, a pure rGO film can be formed without the impurities that normally come from chemical reducing agents. This is an easy and environmentally friendly method to prepare large scale graphene films on Si substrates. PMID:26194107

  6. Efficient Direct Reduction of Graphene Oxide by Silicon Substrate

    PubMed Central

    Chan Lee, Su; Some, Surajit; Wook Kim, Sung; Jun Kim, Sun; Seo, Jungmok; Lee, Jooho; Lee, Taeyoon; Ahn, Jong-Hyun; Choi, Heon-Jin; Chan Jun, Seong

    2015-01-01

    Graphene has been studied for various applications due to its excellent properties. Graphene film fabrication from solutions of graphene oxide (GO) have attracted considerable attention because these procedures are suitable for mass production. GO, however, is an insulator, and therefore a reduction process is required to make the GO film conductive. These reduction procedures require chemical reducing agents or high temperature annealing. Herein, we report a novel direct and simple reduction procedure of GO by silicon, which is the most widely used material in the electronics industry. In this study, we also used silicon nanosheets (SiNSs) as reducing agents for GO. The reducing effect of silicon was confirmed by various characterization methods. Furthermore, the silicon wafer was also used as a reducing template to create a reduced GO (rGO) film on a silicon substrate. By this process, a pure rGO film can be formed without the impurities that normally come from chemical reducing agents. This is an easy and environmentally friendly method to prepare large scale graphene films on Si substrates. PMID:26194107

  7. Titanium oxide as substrate for neural cell growth.

    PubMed

    Carballo-Vila, Mónica; Moreno-Burriel, Berta; Chinarro, Eva; Jurado, José R; Casañ-Pastor, Nieves; Collazos-Castro, Jorge E

    2009-07-01

    Titanium oxide has antiinflammatory activity and tunable electrochemical behavior that make it an attractive material for the fabrication of implantable devices. The most stable composition is TiO2 and occurs mainly in three polymorphs, namely, anatase, rutile, and brookite, which differ in its crystallochemical properties. Here, we report the preparation of rutile surfaces that permit good adherence and axonal growth of cultured rat cerebral cortex neurons. Rutile disks were obtained by sinterization of TiO2 powders of commercial origin or precipitated from hydrolysis of Ti(IV)-isopropoxide. Commercial powders sintered at 1300-1600 degrees C produced rutile surfaces with abnormal grain growth, probably because of impurities of the powders. Neurons cultured on those surfaces survived in variable numbers and showed fewer neurites than on control materials. On the other hand, rutile sintered from precipitated powders had less contaminants and more homogenous grain growth. By adjusting the thermal treatment it was possible to obtain surfaces performing well as substrate for neuron survival for at least 10 days. Some surfaces permitted normal axonal elongation, whereas dendrite growth was generally impaired. These findings support the potential use of titanium oxide in neuroprostheses and other devices demanding materials with enhanced properties in terms of biocompatibility and axon growth promotion. PMID:18481786

  8. Postprandial thermogenesis and substrate oxidation are unaffected by sleep restriction

    PubMed Central

    Shechter, Ari; Rising, Russell; Wolfe, Scott; Albu, Jeanine B.; St-Onge, Marie-Pierre

    2014-01-01

    Background/Objectives The extent to which alterations in energy expenditure (EE) in response to sleep restriction contribute to the short sleep-obesity relationship is not clearly defined. Short sleep may induce changes in resting metabolic rate (RMR), thermic effect of food (TEF), and postprandial substrate oxidation. Subjects/Methods Ten females (age and BMI: 22-43 y and 23.4-28 kg/m2) completed a randomized, crossover study assessing the effects of short (4 h/night) and habitual (8 h/night) sleep duration on fasting and postprandial RMR and respiratory quotient (RQ). Measurements were taken after 3 nights using whole-room indirect calorimetry. The TEF was assessed over a 6-h period following consumption of a high-fat liquid meal. Results Short vs. habitual sleep did not affect RMR (1.01 ± 0.05 and 0.97 ± 0.04 kcal/min; p=0.23). Fasting RQ was significantly lower after short vs. habitual sleep (0.84 ± 0.01 and 0.88 ± 0.01; p=0.028). Postprandial EE (short: 1.13 ± 0.04 and habitual: 1.10 ± 0.04, p=0.09) and RQ (short: 0.88 ± 0.01 and habitual: 0.88 ± 0.01, p=0.50) after the high-fat meal were not different between conditions. TEF was similar between conditions (0.24 ± 0.02 kcal/min in both; p=0.98), as was the ~6-h incremental area under the curve (1.16 ± 0.10 and 1.17 ± 0.09 kcal/min x 356 min after short and habitual sleep, respectively; p=0.92). Conclusions Current findings observed in non-obese healthy premenopausal women do not support the hypothesis that alterations in TEF and postprandial substrate oxidation are major contributors to the higher rate of obesity observed in short sleepers. In exploring a role of sleep duration on EE, research should focus on potential alterations in physical activity to explain the increased obesity risk in short sleepers. PMID:24352294

  9. Composite anodes based on nanotube titanium oxide from electro-oxidation of Ti metal substrate

    NASA Astrophysics Data System (ADS)

    Pozio, A.; Carewska, M.; Mura, F.; D'Amato, R.; Falconieri, M.; De Francesco, M.; Appetecchi, G. B.

    2014-02-01

    In this manuscript is reported an investigation on lithium-ion battery composite anodes based on nanotube titanium oxide active material obtained from electrochemical oxidation of titanium metal substrates. Nanotube TiO2 showed a good nominal capacity, particularly taking into account that no electronic conductive additive as well as no binder was incorporated into the TiO2 material. The performance of nanotube titanium oxide anode tapes was compared with that of electrodes based on TiO2 both commercially available and obtained from laser pyrolysis. Cycling tests have indicated that the anodes based on electrosynthesized nanotube TiO2 exhibit the best performance in terms of capacity values and rate capability in combination with very good capacity retention and coulombic efficiency leveling 100% even at high rates.

  10. Enhanced transparent conducting networks on plastic substrates modified with highly oxidized graphene oxide nanosheets

    NASA Astrophysics Data System (ADS)

    Woo, Jong Seok; Sin, Dong Hun; Kim, Haena; Jang, Jeong In; Kim, Ho Young; Lee, Geon-Woong; Cho, Kilwon; Park, Soo-Young; Han, Joong Tark

    2016-03-01

    Atomically thin and two-dimensional graphene oxide (GO) is a very fascinating material because of its functional groups, high transparency, and solution processability. Here we show that highly oxidized GO (HOGO) nanosheets serve as an effective interfacial modifier of transparent conducting films with one-dimensional (1D) silver nanowires (AgNWs) and single-walled carbon nanotubes (SWCNTs). Optically transparent and small-sized GO nanosheets, with minimal sp2 domains, were successfully fabricated by step-wise oxidation and exfoliation of graphite. We demonstrated that under-coated HOGO further decreases the sheet resistance of the SWCNT film top-coated with HOGO by increasing the contact area between the SWCNTs and HOGO nanosheets by generating hole carriers in the SWCNT as a result of charge transfer. Moreover, HOGO nanosheets with AgNWs contribute to the efficient thermal joining of AgNW networks on plastic substrates by limiting the thermal embedding of AgNWs into the plastic surface, resulting in efficient decrease of the sheet resistance. Furthermore, flexible organic photovoltaic cells with GO-modified AgNW anodes on a flexible substrate were successfully demonstrated.Atomically thin and two-dimensional graphene oxide (GO) is a very fascinating material because of its functional groups, high transparency, and solution processability. Here we show that highly oxidized GO (HOGO) nanosheets serve as an effective interfacial modifier of transparent conducting films with one-dimensional (1D) silver nanowires (AgNWs) and single-walled carbon nanotubes (SWCNTs). Optically transparent and small-sized GO nanosheets, with minimal sp2 domains, were successfully fabricated by step-wise oxidation and exfoliation of graphite. We demonstrated that under-coated HOGO further decreases the sheet resistance of the SWCNT film top-coated with HOGO by increasing the contact area between the SWCNTs and HOGO nanosheets by generating hole carriers in the SWCNT as a result of charge

  11. Enhanced transparent conducting networks on plastic substrates modified with highly oxidized graphene oxide nanosheets.

    PubMed

    Woo, Jong Seok; Sin, Dong Hun; Kim, Haena; Jang, Jeong In; Kim, Ho Young; Lee, Geon-Woong; Cho, Kilwon; Park, Soo-Young; Han, Joong Tark

    2016-03-28

    Atomically thin and two-dimensional graphene oxide (GO) is a very fascinating material because of its functional groups, high transparency, and solution processability. Here we show that highly oxidized GO (HOGO) nanosheets serve as an effective interfacial modifier of transparent conducting films with one-dimensional (1D) silver nanowires (AgNWs) and single-walled carbon nanotubes (SWCNTs). Optically transparent and small-sized GO nanosheets, with minimal sp(2) domains, were successfully fabricated by step-wise oxidation and exfoliation of graphite. We demonstrated that under-coated HOGO further decreases the sheet resistance of the SWCNT film top-coated with HOGO by increasing the contact area between the SWCNTs and HOGO nanosheets by generating hole carriers in the SWCNT as a result of charge transfer. Moreover, HOGO nanosheets with AgNWs contribute to the efficient thermal joining of AgNW networks on plastic substrates by limiting the thermal embedding of AgNWs into the plastic surface, resulting in efficient decrease of the sheet resistance. Furthermore, flexible organic photovoltaic cells with GO-modified AgNW anodes on a flexible substrate were successfully demonstrated. PMID:26946993

  12. Stress generation in thermally grown oxide films. [oxide scale spalling from superalloy substrates

    NASA Technical Reports Server (NTRS)

    Kumnick, A. J.; Ebert, L. J.

    1981-01-01

    A three dimensional finite element analysis was conducted, using the ANSYS computer program, of the stress state in a thin oxide film thermally formed on a rectangular piece of NiCrAl alloy. The analytical results indicate a very high compressive stress in the lateral directions of the film (approximately 6200 MPa), and tensile stresses in the metal substrate that ranged from essentially zero to about 55 MPa. It was found further that the intensity of the analytically determined average stresses could be approximated reasonably well by the modification of an equation developed previously by Oxx for stresses induced into bodies by thermal gradients.

  13. Effect of substrate temperature on structural and electrical properties of RF sputtered hafnium oxide thin films

    SciTech Connect

    Das, K. C.; Ghosh, S. P.; Tripathy, N.; Kar, J. P.; Bose, G.; Lee, T.; Myoung, J. M.

    2015-06-24

    In this work hafnium oxide thin films were deposited on p-type silicon substrate by Radio frequency magnetron sputtering at different substrate temperature ranging from room temperature to 300 °C. The structural and electrical properties of the sputtered films were investigated by x-ray diffraction, capacitance-voltage and current-voltage measurements. The XRD results show the formation monoclinic structure of the hafnium oxide thin films. The shifting of C-V curves towards negative voltage side depicts the increase in positive oxide charges with the rise of substrate temperature. Leakage current was found increased, when temperature enhanced from room temperature to 300 °C.

  14. Novel synthetic methodology for controlling the orientation of zinc oxide nanowires grown on silicon oxide substrates.

    PubMed

    Cho, Jinhyun; Salleh, Najah; Blanco, Carlos; Yang, Sungwoo; Lee, Chul-Jin; Kim, Young-Woo; Kim, Jungsang; Liu, Jie

    2014-04-01

    This study presents a simple method to reproducibly obtain well-aligned vertical ZnO nanowire arrays on silicon oxide (SiOx) substrates using seed crystals made from a mixture of ammonium hydroxide (NH4OH) and zinc acetate (Zn(O2CCH3)2) solution. In comparison, high levels of OH(-) concentration obtained using NaOH or KOH solutions lead to incorporation of Na or K atoms into the seed crystals, destroying the c-axis alignment of the seeds and resulting in the growth of misaligned nanowires. The use of NH4OH eliminates the metallic impurities and ensures aligned nanowire growth in a wide range of OH(-) concentrations in the seed solution. The difference of crystalline orientations between NH4OH- and NaOH-based seeds is directly observed by lattice-resolved images and electron diffraction patterns using a transmission electron microscope (TEM). This study obviously suggests that metallic impurities incorporated into the ZnO nanocrystal seeds are one of the factors that generates the misaligned ZnO nanowires. This method also enables the use of silicon oxide substrates for the growth of vertically aligned nanowires, making ZnO nanostructures compatible with widely used silicon fabrication technology. PMID:24584438

  15. Screening method for selecting semiconductor substrates having defects below a predetermined level in an oxide layer

    DOEpatents

    Warren, W.L.; Vanheusden, K.J.R.; Schwank, J.R.; Fleetwood, D.M.; Shaneyfelt, M.R.; Winokur, P.S.; Devine, R.A.B.

    1998-07-28

    A method is disclosed for screening or qualifying semiconductor substrates for integrated circuit fabrication. The method comprises the steps of annealing at least one semiconductor substrate at a first temperature in a defect-activating ambient (e.g. hydrogen, forming gas, or ammonia) for sufficient time for activating any defects within on oxide layer of the substrate; measuring a defect-revealing electrical characteristic of at least a portion of the oxide layer for determining a quantity of activated defects therein; and selecting substrates for which the quantity of activated defects is below a predetermined level. The defect-revealing electrical characteristic may be a capacitance-versus voltage (C-V) characteristic or a current-versus-voltage (I-V) characteristic that is dependent on an electrical charge in the oxide layer generated by the activated defects. Embodiments of the present invention may be applied for screening any type of semiconductor substrate or wafer having an oxide layer formed thereon or therein. This includes silicon-on-insulator substrates formed by a separation by the implantation of oxygen (SIMOX) process or the bond and etch back silicon-on-insulator (BESOI) process, as well as silicon substrates having a thermal oxide layer or a deposited oxide layer. 5 figs.

  16. Screening method for selecting semiconductor substrates having defects below a predetermined level in an oxide layer

    DOEpatents

    Warren, William L.; Vanheusden, Karel J. R.; Schwank, James R.; Fleetwood, Daniel M.; Shaneyfelt, Marty R.; Winokur, Peter S.; Devine, Roderick A. B.

    1998-01-01

    A method for screening or qualifying semiconductor substrates for integrated circuit fabrication. The method comprises the steps of annealing at least one semiconductor substrate at a first temperature in a defect-activating ambient (e.g. hydrogen, forming gas, or ammonia) for sufficient time for activating any defects within on oxide layer of the substrate; measuring a defect-revealing electrical characteristic of at least a portion of the oxide layer for determining a quantity of activated defects therein; and selecting substrates for which the quantity of activated defects is below a predetermined level. The defect-revealing electrical characteristic may be a capacitance-versus-voltage (C-V) characteristic or a current-versus-voltage (I-V) characteristic that is dependent on an electrical charge in the oxide layer generated by the activated defects. Embodiments of the present invention may be applied for screening any type of semiconductor substrate or wafer having an oxide layer formed thereon or therein. This includes silicon-on-insulator substrates formed by a separation by the implantation of oxygen (SIMOX) process or the bond and etch back silicon-on-insulator (BESOI) process, as well as silicon substrates having a thermal oxide layer or a deposited oxide layer.

  17. Overlay coating degradation by simultaneous oxidation and coating/substrate interdiffusion. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Nesbitt, J. A.

    1983-01-01

    Degradation of NiCrAlZr overlay coatings on various NiCrAl substrates was examined after cyclic oxidation. Concentration/distance profiles were measured in the coating and substrate after various oxidation exposures at 1150 C. For each stubstrate, the Al content in the coating decreased rapidly. The concentration/distance profiles, and particularly that for Al, reflected the oxide spalling resistance of each coated substrate. A numerical model was developed to simulate diffusion associated with overlay-coating degradation by oxidation and coating/substrate interdiffusion. Input to the numerical model consisted of the Cr and Al content of the coating and substrate, ternary diffusivities, and various oxide spalling parameters. The model predicts the Cr and Al concentrations in the coating and substrate after any number of oxidation/thermal cycles. The numerical model also predicts coating failure based on the ability of the coating to supply sufficient Al to the oxide scale. The validity of the model was confirmed by comparison of the predicted and measured concentration/distance profiles. The model was subsequently used to identify the most critical system parameters affecting coating life.

  18. Application of a mixed metal oxide catalyst to a metallic substrate

    NASA Technical Reports Server (NTRS)

    Sevener, Kathleen M. (Inventor); Lohner, Kevin A. (Inventor); Mays, Jeffrey A. (Inventor); Wisner, Daniel L. (Inventor)

    2009-01-01

    A method for applying a mixed metal oxide catalyst to a metallic substrate for the creation of a robust, high temperature catalyst system for use in decomposing propellants, particularly hydrogen peroxide propellants, for use in propulsion systems. The method begins by forming a prepared substrate material consisting of a metallic inner substrate and a bound layer of a noble metal intermediate. Alternatively, a bound ceramic coating, or frit, may be introduced between the metallic inner substrate and noble metal intermediate when the metallic substrate is oxidation resistant. A high-activity catalyst slurry is applied to the surface of the prepared substrate and dried to remove the organic solvent. The catalyst layer is then heat treated to bind the catalyst layer to the surface. The bound catalyst layer is then activated using an activation treatment and calcinations to form the high-activity catalyst system.

  19. Determination of interfacial adhesion strength between oxide scale and substrate for metallic SOFC interconnects

    NASA Astrophysics Data System (ADS)

    Sun, X.; Liu, W. N.; Stephens, E.; Khaleel, M. A.

    The interfacial adhesion strength between the oxide scale and the substrate is crucial to the reliability and durability of metallic interconnects in solid oxide fuel cell (SOFC) operating environments. It is necessary, therefore, to establish a methodology to quantify the interfacial adhesion strength between the oxide scale and the metallic interconnect substrate, and furthermore to design and optimize the interconnect material as well as the coating materials to meet the design life of an SOFC system. In this paper, we present an integrated experimental/analytical methodology for quantifying the interfacial adhesion strength between the oxide scale and a ferritic stainless steel interconnect. Stair-stepping indentation tests are used in conjunction with subsequent finite element analyses to predict the interfacial strength between the oxide scale and Crofer 22 APU substrate.

  20. Nitrosyl-Heme Structures of Bacillus subtilis Nitric Oxide Synthase Have Implications for Understanding Substrate Oxidation

    SciTech Connect

    Pant,K.; Crane, B.

    2006-01-01

    The crystal structures of nitrosyl-heme complexes of a prokaryotic nitric oxide synthase (NOS) from Bacillus subtilis (bsNOS) reveal changes in active-site hydrogen bonding in the presence of the intermediate N{sup {omega}}-hydroxy-L-arginine (NOHA) compared to the substrate L-arginine (L-Arg). Correlating with a Val-to-Ile residue substitution in the bsNOS heme pocket, the Fe(II)-NO complex with both L-Arg and NOHA is more bent than the Fe(II)-NO, L-Arg complex of mammalian eNOS. Structures of the Fe(III)-NO complex with NOHA show a nearly linear nitrosyl group, and in one subunit, partial nitrosation of bound NOHA. In the Fe(II)-NO complexes, the protonated NOHA N{sup {omega}} atom forms a short hydrogen bond with the heme-coordinated NO nitrogen, but active-site water molecules are out of hydrogen bonding range with the distal NO oxygen. In contrast, the L-Arg guanidinium interacts more weakly and equally with both NO atoms, and an active-site water molecule hydrogen bonds to the distal NO oxygen. This difference in hydrogen bonding to the nitrosyl group by the two substrates indicates that interactions provided by NOHA may preferentially stabilize an electrophilic peroxo-heme intermediate in the second step of NOS catalysis.

  1. Process for depositing an oxide epitaxially onto a silicon substrate and structures prepared with the process

    DOEpatents

    McKee, Rodney A.; Walker, Frederick J.

    1993-01-01

    A process and structure involving a silicon substrate utilizes an ultra high vacuum and molecular beam epitaxy (MBE) methods to grow an epitaxial oxide film upon a surface of the substrate. As the film is grown, the lattice of the compound formed at the silicon interface becomes stabilized, and a base layer comprised of an oxide having a sodium chloride-type lattice structure grows epitaxially upon the compound so as to cover the substrate surface. A perovskite may then be grown epitaxially upon the base layer to render a product which incorporates silicon, with its electronic capabilities, with a perovskite having technologically-significant properties of its own.

  2. Substrate Effects on the High Temperature Oxidation Behavior of a Gold-Based Braze Filler Metal

    SciTech Connect

    Weil, K. Scott; Rice, Joseph P.

    2005-06-01

    Oxidation testing was conducted on a commercial gold-based braze alloy, Gold ABA®, and on zirconia/stainless steel couples joined using this filler metal. Preliminary results reveal that both substrates play a significant role in determining the overall oxidation behavior of the brazed joint.

  3. Substrate Effects on the High Temperature Oxidation Behavior of a Gold-Based Braze Filler Metal

    SciTech Connect

    Weil, K. Scott; Rice, Joseph P.

    2005-06-30

    Oxidation testing was conducted on a commercial gold-based braze alloy, Gold ABA, and on zirconia and stainless steel joining couples prepared using this braze filler metal. Preliminary results reveal that both substrates play a significant role in determining the overall oxidation resistance of the brazed joint.

  4. Direct growth of cerium oxide nanorods on diverse substrates for superhydrophobicity and corrosion resistance

    NASA Astrophysics Data System (ADS)

    Cho, Young Jun; Jang, Hanmin; Lee, Kwan-Soo; Kim, Dong Rip

    2015-06-01

    Superhydrophobic surfaces with anti-corrosion properties have attracted great interest in many industrial fields, particularly to enhance the thermal performance of offshore applications such as heat exchangers, pipelines, power plants, and platform structures. Nanostructures with hydrophobic materials have been widely utilized to realize superhydrophobicity of surfaces, and cerium oxide has been highlighted due to its good corrosion resistive and intrinsically hydrophobic properties. However, few studies of direct growth of cerium oxide nanostructures on diverse substrates have been reported. Herein we report a facile hydrothermal method to directly grow cerium oxide nanorods on diverse substrates, such as aluminum alloy, stainless steel, titanium, and silicon. Diverse substrates with cerium oxide nanorods exhibited superhydrophobicity with no hydrophobic modifiers on their surfaces, and showed good corrosion resistive properties in corrosive medium. We believe our method could pave the way for realization of scalable and sustainable corrosion resistive superhydrophobic surfaces in many industrial fields.

  5. Rare earth zirconium oxide buffer layers on metal substrates

    DOEpatents

    Williams, Robert K.; Paranthaman, Mariappan; Chirayil, Thomas G.; Lee, Dominic F.; Goyal, Amit; Feenstra, Roeland

    2001-01-01

    A laminate article comprises a substrate and a biaxially textured (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer over the substrate, wherein 0substrate can be a biaxially textured metal, such as nickel. A method of forming the laminate article is also disclosed.

  6. Fracture toughness of solid oxide fuel cell anode substrates determined by a double-torsion technique

    NASA Astrophysics Data System (ADS)

    Pećanac, G.; Wei, J.; Malzbender, J.

    2016-09-01

    Planar solid oxide fuel cell anode substrates are exposed to high mechanical loads during assembly, start-up, steady-state operation and thermal cycling. Hence, characterization of mechanical stability of anode substrates under different oxidation states and at relevant temperatures is essential to warrant a reliable operation of solid oxide fuel cells. As a basis for mechanical assessment of brittle supports, two most common anode substrate material variants, NiO-3YSZ and NiO-8YSZ, were analyzed in this study with respect to their fracture toughness at room temperature and at a typical stack operation temperature of 800 °C. The study considered both, oxidized and reduced materials' states, where also an outlook is given on the behavior of the re-oxidized state that might be induced by malfunctions of sealants or other functional components. Aiming at the improvement of material's production, different types of warm pressed and tape cast NiO-8YSZ substrates were characterized in oxidized and reduced states. Overall, the results confirmed superior fracture toughness of 3YSZ compared to 8YSZ based composites in the oxidized state, whereas in the reduced state 3YSZ based composites showed similar fracture toughness at room temperature, but a higher value at 800 °C compared to 8YSZ based composites. Complementary microstructural analysis aided the interpretation of mechanical characterization.

  7. Growth of indium oxide nanowalls on patterned conducting substrates: towards direct fabrication of gas sensors.

    PubMed

    Chen, Changlong; Wei, Yuling; Sun, Guoxin; Shao, Baiqi

    2012-05-01

    Nanowall materials are ideal two-dimensional structures with high surface-to-volume ratios and open edge geometries. We first report on the growth and characterization of indium oxide nanowalls on transparent and conducting indium tin oxide substrates. The nanosheets that compose the nanowalls are single-crystalline and are approximately 8 nm in thickness. The density and the lateral dimensions of the nanosheets on the substrate can be controlled by the growth time. Adopting a bridgework-like strategy, we directly construct indium oxide nanowall gas sensors on the patterned indium tin oxide substrates. The pattern lines on the substrates are etched using transparent plastic adhesive tape as shadow mask, which is both simple and cheap in comparison with the conventional photolithography technique. The sensors exhibit fast response/recovery behavior and good reproducibility to NO(2) gas under mild testing conditions, such as room temperature, ambient pressure, dry air background, and 1.5 V dc bias, and can achieve a detection limit as low as 50 ppb. We propose an assumption that the gas adsorption is composed of deep adsorption and probe adsorption to explain the interesting gas-sensing behavior of the indium oxide nanowalls. We suggest that the work reported herein, including the facile growth of indium oxide nanowalls, the bridgework-like strategy to directly construct electronic devices, and the high gas-sensing performance of the indium oxide nanowalls sensors, is a significant step towards the real applications of novel semiconductor nanostructures. PMID:22328146

  8. H2 oxidation versus organic substrate oxidation in non-heme iron mediated reactions with H2O2.

    PubMed

    Hassanpour, Azin; Acuña-Parés, Ferran; Luis, Josep M; Cusso, Olaf; Morales de la Rosa, Silvia; Campos-Martín, José Miguel; Fierro, Jose L G; Costas, Miquel; Lloret-Fillol, Julio; Mas-Ballesté, Rubén

    2015-10-18

    Herein we show that species generated upon reaction of α-[Fe(CF3SO3)2(BPMCN)] (BPMCN = N,N'-bis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane) with H2O2 (putatively [Fe(V)(O)(OH)(BPMCN)]) is able to efficiently oxidize H2 to H2O even in the presence of organic substrates, while species formed in the presence of acetic acid (putatively [Fe(V)(O)(OAc)(BPMCN)]) prefer organic substrate oxidation over H2 activation. Mechanistic implications have been analysed with the aid of computational methods. PMID:26311021

  9. Electrochemically deposited gallium oxide nanostructures on silicon substrates

    PubMed Central

    2014-01-01

    We report a synthesis of β-Ga2O3 nanostructures on Si substrate by electrochemical deposition using a mixture of Ga2O3, HCl, NH4OH, and H2O. The presence of Ga3+ ions contributed to the deposition of Ga2O3 nanostructures on the Si surface with the assistance of applied potentials. The morphologies of the grown structures strongly depended on the molarity of Ga2O3 and pH level of electrolyte. β-Ga2O3 nanodot-like structures were grown on Si substrate at a condition with low molarity of Ga2O3. However, Ga2O3 nanodot structures covered with nanorods on top of their surfaces were obtained at higher molarity, and the densities of nanorods seem to increase with the decrease of pH level. High concentration of Ga3+ and OH- ions may promote the reaction of each other to produce Ga2O3 nanorods in the electrolyte. Such similar nature of Ga2O3 nanorods was also obtained by using hydrothermal process. The grown structures seem to be interesting for application in electronic and optoelectronic devices as well as to be used as a seed structure for subsequent chemical synthesis of GaN by thermal transformation method. PMID:24629107

  10. Complete coverage of reduced graphene oxide on silicon dioxide substrates

    NASA Astrophysics Data System (ADS)

    Huang, Jingfeng; Melanie, Larisika; Chen, Hu; Steve, Faulkner; Myra, A. Nimmo; Christoph, Nowak; Alfred Tok Iing, Yoong

    2014-08-01

    Reduced graphene oxide (RGO) has the advantage of an aqueous and industrial-scale production route. No other approaches can rival the RGO field effect transistor platform in terms of cost (oxide with ethanol, carbon islets are deposited preferentially at the edges of existing flakes. With a 2-h treatment, the standard deviation in electrical resistance of the treated chips can be reduced by 99.95%. Thus this process could enable RGO to be used in practical electronic devices.

  11. Oxidative Attack of Carbon/Carbon Substrates through Coating Pinholes

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Leonhardt, Todd; Curry, Donald; Rapp, Robert A.

    1998-01-01

    A critical issue with oxidation protected carbon/carbon composites used for spacecraft thermal protection is the formation of coating pinholes. In laboratory experiments, artificial pinholes were drilled through SiC-coatings on a carbon/carbon material and the material was oxidized at 600, 1000, and 1400 C at reduced pressures of air. The attack of the carbon/carbon was quantified by both weight loss and a novel cross-sectioning technique. A two-zone, one dimensional diffusion control model was adapted to analyze this problem. Agreement of the model with experiment was reasonable at 1000 and 1400 C; however results at lower temperatures show clear deviations from the theory suggesting that surface reaction control plays a role.

  12. Process for depositing epitaxial alkaline earth oxide onto a substrate and structures prepared with the process

    DOEpatents

    McKee, Rodney A.; Walker, Frederick J.

    1996-01-01

    A process and structure involving a silicon substrate utilize molecular beam epitaxy (MBE) and/or electron beam evaporation methods and an ultra-high vacuum facility to grow a layup of epitaxial alkaline earth oxide films upon the substrate surface. By selecting metal constituents for the oxides and in the appropriate proportions so that the lattice parameter of each oxide grown closely approximates that of the substrate or base layer upon which oxide is grown, lattice strain at the film/film or film/substrate interface of adjacent films is appreciably reduced or relieved. Moreover, by selecting constituents for the oxides so that the lattice parameters of the materials of adjacent oxide films either increase or decrease in size from one parameter to another parameter, a graded layup of films can be grown (with reduced strain levels therebetween) so that the outer film has a lattice parameter which closely approximates that of, and thus accomodates the epitaxial growth of, a pervoskite chosen to be grown upon the outer film.

  13. [Oxidation of sulfur-containing substrates by aboriginal and experimentally designed microbial communities].

    PubMed

    Pivovarova, T A; Bulaev, A G; Roshchupko, P V; Belyĭ, A V; Kondrat'eva, T F

    2012-01-01

    Aboriginal and experimental (constructed of pure microbial cultures) communities of acidophilic chemolithotrophs have been studied. The oxidation of elemental sulfur, sodium thiosulfate, and potassium tetrathionate as sole sources of energy has been monitored. The oxidation rate of the experimental community is higher as compared to the aboriginal community isolated from a flotation concentrate of pyrrhotine-containing pyrite-arsenopyrite gold-arsenic sulfide ore. The degree of oxidation of the mentioned S substrates amounts to 17.91, 68.30, and 93.94% for the experimental microbial community and to 10.71, 56.03, and 79.50% for the aboriginal community, respectively. The degree of oxidation of sulfur sulfide forms in the ore flotation concentrate is 59.15% by the aboriginal microbial community and 49.40% by the experimental microbial community. Despite a higher rate of oxidation of S substrates as a sole source of energy by the experimental microbial community, the aboriginal community oxidizes S substrates at a higher rate in the flotation concentrate of pyrrhotine-containing pyrite-arsenopyrite gold-arsenic sulfide ore, from which it was isolated. Bacterial-chemical oxidation of the flotation concentrate by the aboriginal microbial community allows for the extraction of an additional 32.3% of gold from sulfide minerals, which is by 5.7% larger compared to the yield obtained by the experimental microbial community. PMID:23330391

  14. Electrochemical oxidation of imazapyr with BDD electrode in titanium substrate.

    PubMed

    Souza, F L; Teodoro, T Q; Vasconcelos, V M; Migliorini, F L; Lima Gomes, P C F; Ferreira, N G; Baldan, M R; Haiduke, R L A; Lanza, M R V

    2014-12-01

    In this work we have studied the treatment of imazapyr by electrochemical oxidation with boron-doped diamond anode. Electrochemical degradation experiments were performed in a one-compartment cell containing 0.45 L of commercial formulations of herbicide in the pH range 3.0-10.0 by applying a density current between 10 and 150 mA cm(-2) and in the temperature range 25-45 °C. The maximum current efficiencies were obtained at lower current densities since the electrochemical system is under mass transfer control. The mineralization rate increased in acid medium and at higher temperatures. The treatment was able to completely degrade imazapyr in the range 4.6-100.0 mg L(-1), although the current charge required rises along with the increasing initial concentration of the herbicide. Toxicity analysis with the bioluminescent bacterium Vibrio fischeri showed that at higher pollutant concentrations the toxicity was reduced after the electrochemical treatment. To clarify the reaction pathway for imazapyr mineralization by OH radicals, LC-MS/MS analyses we performed together with a theoretical study. Ions analysis showed the formation of high levels of ammonium in the cathode. The main final products of the electrochemical oxidation of imazapyr with diamond thin film electrodes are formic, acetic and butyric acids. PMID:25461923

  15. Laser patterning of very thin indium tin oxide thin films on PET substrates

    NASA Astrophysics Data System (ADS)

    McDonnell, C.; Milne, D.; Prieto, C.; Chan, H.; Rostohar, D.; O'Connor, G. M.

    2015-12-01

    This work investigates the film removal properties of 30 nm thick Indium Tin Oxide (ITO) thin films, on flexible polyethylene terephthalate (PET) substrates, using 355, 532 and 1064 nm nanosecond pulses (ns), and 343 and 1064 nm femtosecond pulses. The ablation threshold was found to be dependent on the applied wavelength and pulse duration. The surface topography of the laser induced features were examined using atomic force microscopy across the range of wavelengths and pulse durations. The peak temperature, strain and stress tensors were examined in the film and substrate during laser heating, using finite element computational methods. Selective removal of the thin ITO film from the polymer substrate is possible at all wavelengths except at 266 nm, were damage to substrate is observed. The damage to the substrate results in periodic surface structures (LIPPS) on the exposed PET, with a period of twice the incident wavelength. Fragmented crater edges are observed at all nanosecond pulse durations. Film removal using 1030 nm femtosecond pulses results in clean crater edges, however, minor 5 nm damage to the substrate is also observed. The key results show that film removal for ITO on PET, is through film de-lamination across all wavelengths and pulse durations. Film de-lamination occurs due to thermo-elastic stress at the film substrate interface region, as the polymer substrate expands under heating from direct laser absorption and heat conduction across the film substrate interface.

  16. Effect of substrate temperature on electrochromic properties of spray-deposited Ir-oxide thin films

    NASA Astrophysics Data System (ADS)

    Patil, P. S.; Kawar, R. K.; Sadale, S. B.

    2005-08-01

    Electrochromic iridium oxide thin films were prepared by using a simple and inexpensive spray pyrolysis technique onto fluorine doped tin oxide (FTO)-coated glass substrates, from iridium chloride solution. The substrate temperature was varied between 250 and 400 °C. The as-deposited samples were amorphous. The electrochromic properties of thin films were studied in aqueous electrolyte (0.5N H 2SO 4) using cyclic voltammetry (CV), chronoamperometry (CA) and spectroelectrochemical techniques. The films exhibit anodic electrochromism upon intercalation and deintercalation of H + ions. The colouration efficiency at 630 nm was calculated and found maximum for I 250 sample, owing its hydration.

  17. Sex difference in substrate oxidation during low-intensity isometric exercise in young adults.

    PubMed

    Sarafian, Delphine; Schutz, Yves; Montani, Jean-Pierre; Dulloo, Abdul G; Miles-Chan, Jennifer L

    2016-09-01

    Low-intensity physical activity is increasingly promoted as an alternative to sedentary behavior. However, much research to date has focused on moderate- to vigorous-intensity physical activity, and in particular dynamic work, with the effect of low-intensity isometric exercise (<4 METs) on substrate utilization yet to be explored. Here we investigate the effects of such exercise on respiratory quotient (RQ) and determine the extent of intra- and inter-individual variability in response. Energy expenditure, RQ, and substrate oxidation were measured by ventilated-hood indirect calorimetry at rest and in response to standardized, intermittent, low-level isometric leg-press exercises at 5 loads (+5, +10, +15, +20, +25 kg) in 26 healthy, young adults. Nine participants repeated the experiment on 3 separate days to assess within-subject, between-day variability. There was no significant difference in energy cost and heart rate responses to low-intensity isometric exercise (<2 METs) between men and women. However, a sex difference was apparent in terms of substrate oxidation - with men increasing both fat and carbohydrate oxidation, and women only increasing fat oxidation while maintaining carbohydrate oxidation at baseline, resting levels. This sex difference was repeatable and persisted when substrate oxidation was adjusted for differences in body weight or body composition. Individual variability in RQ was relatively low, with both intra- and inter-individual coefficients of variation in the range of 3%-6% in both sexes. These results suggest that women preferentially increase fat oxidation during low-level isometric exercise. Whether such physical activity could be incorporated into treatment/prevention strategies aimed at optimizing fat oxidation in women warrants further investigation. PMID:27540628

  18. Protective Effect of Selected Medicinal Plants against Hydrogen Peroxide Induced Oxidative Damage on Biological Substrates.

    PubMed

    Pai Kotebagilu, Namratha; Reddy Palvai, Vanitha; Urooj, Asna

    2014-01-01

    Oxidative stress is developed due to susceptibility of biological substrates to oxidation by generation of free radicals. In degenerative diseases, oxidative stress level can be reduced by antioxidants which neutralize free radicals. Primary objective of this work was to screen four medicinal plants, namely, Andrographis paniculata, Costus speciosus, Canthium parviflorum, and Abrus precatorius, for their antioxidant property using two biological substrates-RBC and microsomes. The antioxidative ability of three solvent extracts, methanol (100% and 80%) and aqueous leaf extracts, was studied at different concentrations by thiobarbituric acid reactive substances method using Fenton's reagent to induce oxidation in the substrates. The polyphenol and flavonoid content were analyzed to relate with the observed antioxidant effect of the extracts. The phytochemical screening indicated the presence of flavonoids, polyphenols, tannins, and β-carotene in the samples. In microsomes, 80% methanol extract of Canthium and Costus and, in RBC, 80% methanol extract of Costus showed highest inhibition of oxidation and correlated well with the polyphenol and flavonoid content. From the results it can be concluded that antioxidants from medicinal plants are capable of inhibiting oxidation in biological systems, suggesting scope for their use as nutraceuticals. PMID:25436152

  19. Thermally-driven structural changes of graphene oxide multilayer films deposited on glass substrate

    NASA Astrophysics Data System (ADS)

    Lazauskas, A.; Baltrusaitis, J.; Grigaliūnas, V.; Guobienė, A.; Prosyčevas, I.; Narmontas, P.; Abakevičienė, B.; Tamulevičius, S.

    2014-11-01

    Graphene oxide (GO) has been recognized as an important intermediate compound for a potential low-cost large-scale graphene-like film fabrication. In this work, graphene oxide multilayer films deposited on glass substrate were reduced using different thermal reduction methods, including low-temperature annealing, flame-induced and laser reduction, and the corresponding surface morphology and structural properties were investigated. These graphene oxide thermal reduction methods strongly affected surface morphology and differently facilitated structural and chemical transformations of graphene oxide. As evidenced by Raman measurements, thermal annealing and laser reduction of graphene oxide produced more ordered graphene-like structure multilayer films. However, surface morphological differences were observed and attributed to the different de-oxidation mechanisms of GO. This Letter provides an important systematic comparison between the GO reduction methods and thermally-driven structural changes they provide to the reduced GO multilayer films obtained.

  20. Benzene oxide is a substrate for glutathione S-transferases.

    PubMed

    Zarth, Adam T; Murphy, Sharon E; Hecht, Stephen S

    2015-12-01

    Benzene is a known human carcinogen which must be activated to benzene oxide (BO) to exert its carcinogenic potential. BO can be detoxified in vivo by reaction with glutathione and excretion in the urine as S-phenylmercapturic acid. This process may be catalyzed by glutathione S-transferases (GSTs), but kinetic data for this reaction have not been published. Therefore, we incubated GSTA1, GSTT1, GSTM1, and GSTP1 with glutathione and BO and quantified the formation of S-phenylglutathione. Kinetic parameters were determined for GSTT1 and GSTP1. At 37 °C, the putative Km and Vmax values for GSTT1 were 420 μM and 450 fmol/s, respectively, while those for GSTP1 were 3600 μM and 3100 fmol/s. GSTA1 and GSTM1 did not exhibit sufficient activity for determination of kinetic parameters. We conclude that GSTT1 is a critical enzyme in the detoxification of BO and that GSTP1 may also play an important role, while GSTA1 and GSTM1 seem to be less important. PMID:26554337

  1. Oxidation of ultrafast radical clock substrate probes by the soluble methane monooxygenase from Methylococcus capsulatus (Bath).

    PubMed

    Valentine, A M; LeTadic-Biadatti, M H; Toy, P H; Newcomb, M; Lippard, S J

    1999-04-16

    Radical clock substrate probes were used to assess the viability of a discrete substrate radical species in the mechanism of hydrocarbon oxidation by the soluble methane monooxygenase (sMMO) from Methylococcus capsulatus (Bath). New substituted cyclopropane probes were used with very fast ring-opening rate constants and other desirable attributes, such as the ability to discriminate between radical and cationic intermediates. Oxidation of these substrates by a reconstituted sMMO system resulted in no rearranged products, allowing an upper limit of 150 fs to be placed on the lifetime of a putative radical species. This limit strongly suggests that there is no such substrate radical intermediate. The two enantiomers of trans-1-methyl-2-phenyl-cyclopropane were prepared, and the regioselectivity of their oxidation to the corresponding cyclopropylmethanol and cyclopropylphenol products was determined. The results are consistent with selective orientation of the two enantiomeric substrates in the hydrophobic cavity at the active site of sMMO, specific models for which were examined by molecular modeling. PMID:10196150

  2. Bovine plasma amine oxidase (PAO) oxidizes substrate by a proton activation mechanism

    SciTech Connect

    Hartmann, C.; Klinman, J.P.

    1986-05-01

    PAO catalyzes the oxidative deamination of amines to aldehydes, concomitant with a 2e/sup -/ reduction of O/sub 2/ to H/sub 2/O/sub 2/. Several investigators have proposed recently that the organic cofactor in PAO is pyrroloquinoline quinone (PQQ), hitherto seen exclusively in prokaryotes. The structure and properties of PQQ predict first, that substrate and PAO will form a covalent adduct and second, that substrate will be oxidized via proton abstraction. In earlier studies from this laboratory, steady state isotope effects, in conjunction with an intrinsic isotope effect, have been shown to provide microscopic rate constants from complex mechanisms. In this study, V, D/sub V/, V/K and /sup D/(V/K) have been measured for the oxidation of a series of nine ring-substituted benzylamines and (1-/sup 2/H/sub 2/)-benzylamines with PAO. The series of substrates was chosen to minimize collinearity in the electronic and hydrophobic properties of ring substituents. Computed rate constants for the C-H bond cleavage step indicate a strong correlation with electron withdrawing substituents, rho = 1.3, confirming the formation of a discrete carbanion intermediate upon substrate activation. Additional studies are in progress, with the objective of trapping and characterizing the putative adduct between PAO and substrates.

  3. Species identification of Aeromonas strains based on carbon substrate oxidation profiles.

    PubMed Central

    Carnahan, A M; Joseph, S W; Janda, J M

    1989-01-01

    Twenty clinical strains each of Aeromonas hydrophila, Aeromonas caviae, and Aeromonas sobria were evaluated for their abilities to oxidize one or more of 95 carbon sources on a GN Microplate (BIOLOG, Hayward, Calif.). Nine substrates yielded good, discriminatory values for the three species tested. The panel appears to be useful for the species identification of Aeromonas isolates originating from human material. PMID:2778077

  4. Microplasmas for direct, substrate-independent deposition of nanostructured metal oxides

    NASA Astrophysics Data System (ADS)

    Mackie, Katherine E.; Pebley, Andrew C.; Butala, Megan M.; Zhang, Jinping; Stucky, Galen D.; Gordon, Michael J.

    2016-07-01

    A general, substrate-independent method for plasma deposition of nanostructured, crystalline metal oxides is presented. The technique uses a flow-through, micro-hollow cathode plasma discharge (supersonic microplasma jet) with a "remote" ring anode to deliver a highly directed flux of growth species to the substrate. A diverse range of nanostructured materials (e.g., CuO, α-Fe2O3, and NiO) can be deposited on any room temperature surface, e.g., conductors, insulators, plastics, fibers, and patterned surfaces, in a conformal fashion. The effects of deposition conditions, substrate type, and patterning on film morphology, nanostructure, and surface coverage are highlighted. The synthesis approach presented herein provides a general and tunable method to deposit a variety of functional and hierarchical metal oxide materials on many different surfaces. High surface area, conversion-type CuO electrodes for Li-ion batteries are demonstrated as a proof-of-concept example.

  5. Copper substrate as a catalyst for the oxidation of chemical vapor deposition-grown graphene

    SciTech Connect

    Li, Zhiting; Zhou, Feng; Parobek, David; Shenoy, Ganesh J.; Muldoon, Patrick; Liu, Haitao

    2015-04-15

    We report the catalytic effect of copper substrate on graphene–oxygen reaction at high temperature. Previous studies showed that graphene grown on copper are mostly defect-free with strong oxidation resistance. We found that a freshly prepared copper-supported graphene sample can be completely oxidized in trace amount of oxygen (<3 ppm) at 600 °C within 2 h. Both X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) suggest that upon ambient air exposure, oxygen molecules diffuse into the space between graphene and copper, resulting in the formation of copper oxide which acts as catalytic sites for the graphene-oxygen reaction. This result has important implications for the characterization, processing, and storage of copper-supported graphene samples. - Graphical abstract: The copper substrate enhances the thermel oxidation of single-layer graphene. - Highlights: • A copper-supported graphene can be oxidized in Ar (O{sub 2}<3 ppm, 600 °C, 2 h). • O{sub 2} intercalates between graphene and copper upon exposure to air. • The copper foil should not be considered as an inert substrate.

  6. Copper Oxide Substrates and Epitaxial Copper Oxide/Zinc Oxide Thin Film Heterostructures for Solar Energy Conversion

    NASA Astrophysics Data System (ADS)

    Darvish, Davis Solomon

    Future fossil fuel scarcity and environmental degradation have demonstrated the need for renewable, low-carbon sources of energy to power an increasingly industrialized world. Solar energy with its infinite supply makes it an extraordinary resource that should not go unused. However with current materials, adoption is limited by cost and so a paradigm shift must occur to get everyone on the same page embracing solar technology. Cuprous Oxide (Cu2O) is a promising earth abundant material that can be a great alternative to traditional thin-film photovoltaic materials like CIGS, CdTe, etc. We have prepared Cu 2O bulk substrates by the thermal oxidation of copper foils as well Cu2O thin films deposited via plasma-assisted Molecular Beam Epitaxy. From preliminary Hall measurements it was determined that Cu2O would need to be doped extrinsically. This was further confirmed by simulations of ZnO/Cu2O heterojunctions. A cyclic interdependence between, defect concentration, minority carrier lifetime, film thickness, and carrier concentration manifests itself a primary reason for why efficiencies greater than 4% has yet to be realized. Our growth methodology for our thin-film heterostructures allow precise control of the number of defects that incorporate into our film during both equilibrium and nonequilibrium growth. We also report process flow/device design/fabrication techniques in order to create a device. A typical device without any optimizations exhibited open-circuit voltages Voc, values in excess 500mV; nearly 18% greater than previous solid state devices.

  7. Effect of Phosphate and Uncouplers on Substrate Transport and Oxidation by Isolated Corn Mitochondria 1

    PubMed Central

    Day, David A.; Hanson, John B.

    1977-01-01

    A study was made to determine conditions under which malate oxidation rates in corn (Zea mays L.) mitochondria are limited by transport processes. In the absence of added ADP, inorganic phosphate increased malate oxidation rates by processes inhibited by mersalyl and oligomycin, but phosphate did not stimulate uncoupled respiration. However, the uncoupled oxidation rates were inhibited by butylmalonate and mersalyl. When uncoupler was added prior to substrate, subsequent O2 uptake rates were reduced when malate and succinate, but not exogenous NADH, were used. Uncoupler and butylmalonate also inhibited swelling in malate solutions and malate accumulation by these mitochondria, which were found to have a high endogenous phosphate content. Addition of uncoupler after malate or succinate produced an initial rapid oxidation which declined as the mitochondria lost solute and contracted. This decline was not affected by addition of ADP or AMP, and was not observed when exogenous NADH was substrate. Increasing K+ permeability with valinomycin increased the P-trifluoromethoxy (carboxylcyanide)phenyl hydrazone inhibition. Kinetic studies showed the slow rate of malate oxidation in the presence of uncoupler to be characterized by a high Km and a low Vmax, probably reflecting a diffusion-limited process. The results indicate that rapid malate and succinate oxidation require the operation of both the phosphate and dicarboxylate transporters, which in turn depend on maintenance of a proton motive force across the inner membrane. In addition, phosphate can stimulate acceptorless malate oxidation by reaction with the coupling mechanism, and in uncoupled mitochondria which are depleted of substrate there is a slow rate of oxidation which appears to be limited by diffusive entry. PMID:16659803

  8. Substrate inhibition: Oxidation of D-sorbitol and D-mannitol by potassium periodate in alkaline medium

    NASA Astrophysics Data System (ADS)

    Lakshman Kumar, Y.; Venkata Nadh, R.; Radhakrishnamurti, P. S.

    2014-05-01

    In the oxidation of D-sorbitol and D-mannitol by potassium periodate in alkaline media, substrate inhibition was observed with both substrates, i.e., a decrease in the rate of the reaction was observed with an increase in the concentration of substrate. The substrate inhibition was attributed to the formation of stable complex between the substrate and periodate. The reactions were found to be first order in case of periodate and a positive fractional order with hydroxide ions. Arrhenius parameters were calculated for the oxidation of sorbitol and mannitol by potassium periodate in alkali media.

  9. Structure, stability and electrochromic properties of polyaniline film covalently bonded to indium tin oxide substrate

    NASA Astrophysics Data System (ADS)

    Zhang, Wenzhi; Ju, Wenxing; Wu, Xinming; Wang, Yan; Wang, Qiguan; Zhou, Hongwei; Wang, Sumin; Hu, Chenglong

    2016-03-01

    Indium tin oxide (ITO) substrate was modified with 4-aminobenzylphosphonic acid (ABPA), and then the polyaniline (PANI) film covalently bonded to ITO substrate was prepared by the chemical oxidation polymerization. X-ray photoelectron spectroscopy (XPS), attenuated total reflection infrared (ATR-IR) spectroscopy, and atomic force microscopy (AFM) measurements demonstrated that chemical binding was formed between PANI and ABPA-modified ITO surface, and the maximum thickness of PANI layer is about 30 nm. The adhesive strength of PANI film on ITO substrate was tested by sonication. It was found that the film formed on the modified ITO exhibited a much better stability than that on bare one. Cyclic voltammetry (CV) and UV-vis spectroscopy measurements indicated that the oxidative potentials of PANI film on ABPA-modified ITO substrate were decreased and the film exhibited high electrochemical activities. Moreover, the optical contrast increased from 0.58 for PANI film (without ultrasound) to 1.06 for PANI film (after ultrasound for 60 min), which had an over 83% enhancement. The coloration time was 20.8 s, while the bleaching time was 19.5 s. The increase of electrochromic switching time was due to the lower ion diffusion coefficient of the large cation of (C4H9)4N+ under the positive and negative potentials as comparison with the small Li+ ion.

  10. In-situ Reflectance Monitoring of GaSb Substrate Oxide Desorption

    SciTech Connect

    C.J. Vineis; C.A. Wang; K.F. Jensen

    2000-08-21

    The use of specular reflectance to monitor GaSb substrate oxide desorption in-situ is reported. Substrates were loaded into the organometallic vapor phase epitaxy reactor either as-received (epi-ready) or after receiving a solvent degrease, acid etch and rinse. A variety of surface preparations and anneal conditions were investigated. HCL was used as the etchant, and in certain cases was followed by an additional etch in Br{sub 2}-HCl-HNO{sub 3}-CH{sub 3}COOH for comparison. Rinse comparisons included 2-propanol, methanol, and deionized water. Substrates were heated to either 525, 550, or 575 C. Features observed in the in-situ reflectance associated with the oxide desorption process were interpreted based on the starting oxide chemistry and thickness. Based on in-situ reflectance and ex-situ atomic force microscopy data, a recommendation on a reproducible GaSb substrate preparation technique suitable for high-quality epitaxial growth is suggested.

  11. Protective Effect of Selected Medicinal Plants against Hydrogen Peroxide Induced Oxidative Damage on Biological Substrates

    PubMed Central

    Pai Kotebagilu, Namratha; Reddy Palvai, Vanitha

    2014-01-01

    Oxidative stress is developed due to susceptibility of biological substrates to oxidation by generation of free radicals. In degenerative diseases, oxidative stress level can be reduced by antioxidants which neutralize free radicals. Primary objective of this work was to screen four medicinal plants, namely, Andrographis paniculata, Costus speciosus, Canthium parviflorum, and Abrus precatorius, for their antioxidant property using two biological substrates—RBC and microsomes. The antioxidative ability of three solvent extracts, methanol (100% and 80%) and aqueous leaf extracts, was studied at different concentrations by thiobarbituric acid reactive substances method using Fenton's reagent to induce oxidation in the substrates. The polyphenol and flavonoid content were analyzed to relate with the observed antioxidant effect of the extracts. The phytochemical screening indicated the presence of flavonoids, polyphenols, tannins, and β-carotene in the samples. In microsomes, 80% methanol extract of Canthium and Costus and, in RBC, 80% methanol extract of Costus showed highest inhibition of oxidation and correlated well with the polyphenol and flavonoid content. From the results it can be concluded that antioxidants from medicinal plants are capable of inhibiting oxidation in biological systems, suggesting scope for their use as nutraceuticals. PMID:25436152

  12. EXAMINATION OF THE OXIDATION PROTECTION OF ZINC COATINGS FORMED ON COPPER ALLOYS AND STEEL SUBSTRATES

    SciTech Connect

    Papazoglou, M.; Chaliampalias, D.; Vourlias, G.; Pavlidou, E.; Stergioudis, G.; Skolianos, S.

    2010-01-21

    The exposure of metallic components at aggressive high temperature environments, usually limit their usage at similar application because they suffer from severe oxidation attack. Copper alloys are used in a wide range of high-quality indoor and outdoor applications, statue parts, art hardware, high strength and high thermal conductivity applications. On the other hand, steel is commonly used as mechanical part of industrial set outs or in the construction sector due to its high mechanical properties. The aim of the present work is the examination of the oxidation resistance of pack cementation zinc coatings deposited on copper, leaded brass and steel substrates at elevated temperature conditions. Furthermore, an effort made to make a long-term evaluation of the coated samples durability. The oxidation results showed that bare substrates appear to have undergone severe damage comparing with the coated ones. Furthermore, the mass gain of the uncoated samples was higher than this of the zinc covered ones. Particularly zinc coated brass was found to be more resistant to oxidation conditions in which it was exposed as it has the lower mass gain as compared to the bare substrates and zinc coated copper. Zinc coated steel was also proved to be more resistive than the uncoated steel.

  13. Low-voltage protonic/electronic hybrid indium zinc oxide synaptic transistors on paper substrates

    NASA Astrophysics Data System (ADS)

    Wu, Guodong; Wan, Changjin; Zhou, Jumei; Zhu, Liqiang; Wan, Qing

    2014-03-01

    Low-voltage (1.5 V) indium zinc oxide (IZO)-based electric-double-layer (EDL) thin-film transistors (TFTs) gated by nanogranular proton conducting SiO2 electrolyte films are fabricated on paper substrates. Both enhancement-mode and depletion-mode operation are obtained by tuning the thickness of the IZO channel layer. Furthermore, such flexible IZO protonic/electronic hybrid EDL TFTs can be used as artificial synapses, and synaptic stimulation response and short-term synaptic plasticity function are demonstrated. The protonic/electronic hybrid EDL TFTs on paper substrates proposed here are promising for low-power flexible paper electronics, artificial synapses and bioelectronics.

  14. Highly flexible, hybrid-structured indium tin oxides for transparent electrodes on polymer substrates

    SciTech Connect

    Triambulo, Ross E.; Kim, Jung-Hoon; Park, Jin-Woo; Na, Min-Young; Chang, Hye-Jung

    2013-06-17

    We developed highly flexible, hybrid-structured crystalline indium tin oxide (ITO) for use as transparent electrodes on polymer substrates by embedding Ag nanoparticles (AgNPs) into the substrate. The hybrid ITO consists of domains in one orientation grown on the AgNPs and a matrix of the other orientation. The domains are stronger than the matrix and function as barriers to crack propagation. As a result, both the critical bending radius (r{sub c}) (under which the resistivity change ({Delta}{rho}) is less than a given value) and the change in {Delta}{rho} with decreasing r significantly decreased in the hybrid ITO compared with homogenous ITO.

  15. X-ray Characterisation of Zinc Oxide (ZnO) Single Crystal Substrates

    SciTech Connect

    Dhanaraj, G.; Raghothamachar, B; Dudley, M

    2010-01-01

    Single crystal substrates of low defect density are paramount for fully realizing the numerous applications of zinc oxide (ZnO) wide bandgap semiconductors. While ZnO substrates are commercially available from various vendors, very little information is available on the structural properties of these substrates. Therefore, an extensive evaluation of available substrates would serve as a basis for the development of ZnO based devices and technologies. In this study, bulk ZnO single crystal substrates grown by different growth techniques have been characterised using synchrotron white beam X-ray topography and high resolution X-ray diffraction. The substrates exhibit a wide range of dislocation densities from as high as 10{sup 6} cm{sup -2} down to less than 1000 cm{sup -2} depending on the growth technique employed. The authors evaluation reveals that ZnO crystals grown by the hydrothermal technique possess the best structural quality with dislocation densities of 800-1000 cm{sup -2} and rocking curves with a full width half maximum of less than 12 arc seconds.

  16. Solution processable broadband transparent mixed metal oxide nanofilm optical coatings via substrate diffusion doping

    NASA Astrophysics Data System (ADS)

    Glynn, Colm; Aureau, Damien; Collins, Gillian; O'Hanlon, Sally; Etcheberry, Arnaud; O'Dwyer, Colm

    2015-11-01

    Devices composed of transparent materials, particularly those utilizing metal oxides, are of significant interest due to increased demand from industry for higher fidelity transparent thin film transistors, photovoltaics and a myriad of other optoelectronic devices and optics that require more cost-effective and simplified processing techniques for functional oxides and coatings. Here, we report a facile solution processed technique for the formation of a transparent thin film through an inter-diffusion process involving substrate dopant species at a range of low annealing temperatures compatible with processing conditions required by many state-of-the-art devices. The inter-diffusion process facilitates the movement of Si, Na and O species from the substrate into the as-deposited vanadium oxide thin film forming a composite fully transparent V0.0352O0.547Si0.4078Na0.01. Thin film X-ray diffraction and Raman scattering spectroscopy show the crystalline component of the structure to be α-NaVO3 within a glassy matrix. This optical coating exhibits high broadband transparency, exceeding 90-97% absolute transmission across the UV-to-NIR spectral range, while having low roughness and free of surface defects and pinholes. The production of transparent films for advanced optoelectronic devices, optical coatings, and low- or high-k oxides is important for planar or complex shaped optics or surfaces. It provides opportunities for doping metal oxides to ternary, quaternary or other mixed metal oxides on glass, encapsulants or other substrates that facilitate diffusional movement of dopant species.Devices composed of transparent materials, particularly those utilizing metal oxides, are of significant interest due to increased demand from industry for higher fidelity transparent thin film transistors, photovoltaics and a myriad of other optoelectronic devices and optics that require more cost-effective and simplified processing techniques for functional oxides and coatings

  17. Anomalous charge trapping dynamics in cerium oxide grown on germanium substrate

    NASA Astrophysics Data System (ADS)

    Rahman, M. S.; Evangelou, E. K.; Dimoulas, A.; Mavrou, G.; Galata, S.

    2008-03-01

    We have observed charge trapping phenomena in thin films of cerium oxide on n-type germanium (Ge) substrate under constant voltage stress (CVS) condition. The measured shift of the flatband voltage of a high frequency C-V curve immediately after each CVS cycle, was utilized as a method to study the capture dynamics of both preexisting and stress induced oxide defects. At low stress electric field, it is the creation of new interface traps that dominates the trapping characteristics of the corresponding metal-oxide semiconductor capacitors. At higher stress electric field, negative charges are trapped on preexisting traps uniformly located in the bulk of the oxide. From data analysis, the capture cross section of the traps is estimated to be around 1×10-19cm2 which indicates neutral traps possibly related to H+ species and/or oxygen vacancies.

  18. Solution processable broadband transparent mixed metal oxide nanofilm optical coatings via substrate diffusion doping.

    PubMed

    Glynn, Colm; Aureau, Damien; Collins, Gillian; O'Hanlon, Sally; Etcheberry, Arnaud; O'Dwyer, Colm

    2015-12-21

    Devices composed of transparent materials, particularly those utilizing metal oxides, are of significant interest due to increased demand from industry for higher fidelity transparent thin film transistors, photovoltaics and a myriad of other optoelectronic devices and optics that require more cost-effective and simplified processing techniques for functional oxides and coatings. Here, we report a facile solution processed technique for the formation of a transparent thin film through an inter-diffusion process involving substrate dopant species at a range of low annealing temperatures compatible with processing conditions required by many state-of-the-art devices. The inter-diffusion process facilitates the movement of Si, Na and O species from the substrate into the as-deposited vanadium oxide thin film forming a composite fully transparent V0.0352O0.547Si0.4078Na0.01. Thin film X-ray diffraction and Raman scattering spectroscopy show the crystalline component of the structure to be α-NaVO3 within a glassy matrix. This optical coating exhibits high broadband transparency, exceeding 90-97% absolute transmission across the UV-to-NIR spectral range, while having low roughness and free of surface defects and pinholes. The production of transparent films for advanced optoelectronic devices, optical coatings, and low- or high-k oxides is important for planar or complex shaped optics or surfaces. It provides opportunities for doping metal oxides to ternary, quaternary or other mixed metal oxides on glass, encapsulants or other substrates that facilitate diffusional movement of dopant species. PMID:26575987

  19. Electrochromic properties of vanadium oxide thin films prepared by PSPT: Effect of substrate temperature

    NASA Astrophysics Data System (ADS)

    Patil, C. E.; Jadhav, P. R.; Tarwal, N. L.; Deshmukh, H. P.; Karanjakar, M. M.; Wali, A. A.; Patil, P. S.

    2013-06-01

    Electrochromic vanadium oxide (V2O5) thin films were deposited onto glass and fluorine doped tin oxide (FTO) coated glass substrates from methanolic vanadium chloride solution by pulsed spray pyrolysis technique (PSPT). The films were synthesized at different substrate temperatures ranging from 350°C-450°C with a temperature step of 50°C. The structural, morphological, optical and electrochromic properties of the synthesized films were investigated. The films were polycrystalline with tetragonal crystal structure. Scanning electron microscopy reveals compact morphology at high temperature. All films exhibited cathodic electrochromism in lithium containing electrolyte (0.5 M LiClO4 + Propylene Carbonate). Maximum coloration efficiency (CE) 15.16 cm2C-1, was observed for the films deposited at 350°C.

  20. Dye-sensitized solar cells based on different nano-oxides on plastic PET substrate

    NASA Astrophysics Data System (ADS)

    Mikula, Milan; Gemeiner, Pavol; Beková, Zuzana; Dvonka, Vladimír; Búc, Dalibor

    2015-01-01

    Polyethylene-terephthalate (PET) foils and glass slides coated with thin conductive layers were used as substrates for TiO2 or ZnO based photoactive electrodes of dye-sensitized solar cells (DSSC) with organo-metallic Ru-dye, standard iodine electrolyte and Pt coated FTO/glass counterelectrode (CE). Different compositions of nanoparticle oxides in forms of alcohol pastes as well as the CE paste were applied onto the substrates by screen printing or by doctor blade techniques. Photocurrents and I-V loading characteristics were measured depending on the solar cell structure and preparation, including the oxide composition, electrode conductivity and the dye type. The influence of thin TiO2 blocking layer prepared by sol-gel technique is also discussed.

  1. Preparation of hydroxyapatite-containing titania coating on titanium substrate by micro-arc oxidation

    SciTech Connect

    Ni Jiahua; Shi Yulong Yan Fengying; Chen Jianzhi; Wang Lei

    2008-01-08

    Hydroxyapatite-containing titania coatings on titanium substrates were formed by micro-arc oxidation (MAO) in electrolyte containing calcium acetate monohydrate (CH{sub 3}COO){sub 2}Ca.H{sub 2}O) and sodium phosphate monobasic dihydrate (NaH{sub 2}PO{sub 4}.2H{sub 2}O) using a pulse power supply. Scanning electron microscopy (SEM) with Energy dispersive X-ray spectrometer (EDX) and X-ray diffraction (XRD) were employed to characterize the microstructure, elemental composition and phase components of the coatings. The coatings were rough and porous, without apparent interface to the titanium substrates. All the oxidized coatings contained Ca and P as well as Ti and O, and the porous coatings were made up of anatase, rutile and hydroxyapatite. Such MAO films are expected to have significant applications as artificial bone joints and dental implants.

  2. Multiwell 14CO2-capture assay for evaluation of substrate oxidation rates of cells in culture.

    PubMed

    Collins, C L; Bode, B P; Souba, W W; Abcouwer, S F

    1998-05-01

    14CO2 capture is commonly used to evaluate the cellular oxidation rate of respiratory substrates. A modification of the established 14CO2-capture method was developed that enables the use of cells in adherent culture and easy analysis of multiple samples under different culture conditions. The use of commercially available culture and filter plates designed for use in a multiplate scintillation spectrophotometer enabled substrate oxidation rates to be evaluated for cells in a 24-well plate format without the need to dislodge the cells from the culture substrate as is required in traditional methods. Evaluation of radioactivity captured in potassium hydroxide-saturated filters was accomplished by adding scintillation fluid to the filter plate wells and counting. Alternatively, filters could be removed and placed in vials for evaluation in a conventional scintillation counter. This method was applied to the oxidation of 14C-glutamine by human breast cell lines and demonstrated concentration-dependent linear accumulation of captured counts. PMID:9591130

  3. Low-voltage indium gallium zinc oxide thin film transistors on paper substrates

    NASA Astrophysics Data System (ADS)

    Lim, Wantae; Douglas, E. A.; Norton, D. P.; Pearton, S. J.; Ren, F.; Heo, Young-Woo; Son, S. Y.; Yuh, J. H.

    2010-02-01

    We have fabricated bottom-gate amorphous (α-) indium-gallium-zinc-oxide (InGaZnO4) thin film transistors (TFTs) on both paper and glass substrates at low processing temperature (≤100 °C). As a water and solvent barrier layer, cyclotene (BCB 3022-35 from Dow Chemical) was spin-coated on the entire paper substrate. TFTs on the paper substrates exhibited saturation mobility (μsat) of 1.2 cm2 V-1 s-1, threshold voltage (VTH) of 1.9 V, subthreshold gate-voltage swing (S ) of 0.65 V decade-1, and drain current on-to-off ratio (ION/IOFF) of ˜104. These values were only slightly inferior to those obtained from devices on glass substrates (μsat˜2.1 cm2 V-1 s-1, VTH˜0 V, S ˜0.74 V decade-1, and ION/IOFF=105-106). The uneven surface of the paper sheet led to relatively poor contact resistance between source-drain electrodes and channel layer. The ability to achieve InGaZnO TFTs on cyclotene-coated paper substrates demonstrates the enormous potential for applications such as low-cost and large area electronics.

  4. [Characterization of peroxidase-catalyzed oxidation of chromogenic substrates by tetrazole and its 5-substituted derivatives].

    PubMed

    Karaseva, E I; Gaponik, P N; Metelitsa, D I

    2005-01-01

    Peroxidase-catalyzed oxidation of 2,2-azino-di(3-ethyl-benzthiazolydine-6-sulfonic acid) (ABTS) and 3,3',5,5'-tetramethylbenzidine (TMB) is activated by tetrazole and its 5-substituted derivatives--5-amino-(AmT), 5-methyl- (MeT), 5-phenyl- (PhT), and 5-CF3- (CF3-T) tetrazoles. In phosphate-citrate or phosphate buffer (pH 6.4 or 7.2; 20 degrees C), the activating effect of tetrazoles on TMB and ABTS oxidation decreased in the series AmT > MeT > T > PhT > CF3-T and T > AmT > MeT > PhT, respectively. The (coefficient) degree of activation (alpha), expressed in M(-1), determined for both substrates and all activators, depended on substrate type, buffer nature, and pH (it increased as pH increased from 6.4 to 7.2). For TMB oxidation, good correlation between lgalpha and the Hammet constants sigma(meta) for m-substituents in the benzene series NH2, CH3, C6H5, and CF3 was found. It is suggested that AmT, MeT, and T can be used as activators of peroxidase-catalyzed oxidation of TMB and ABTS, as well as in designing peroxidase-based biosensors. PMID:15859456

  5. Raman spectroscopy analysis of air grown oxide scale developed on pure zirconium substrate

    NASA Astrophysics Data System (ADS)

    Kurpaska, L.; Favergeon, J.; Lahoche, L.; El-Marssi, M.; Grosseau Poussard, J.-L.; Moulin, G.; Roelandt, J.-M.

    2015-11-01

    Using Raman spectroscopy technique, external and internal parts of zirconia oxide films developed at 500 °C and 600 °C on pure zirconium substrate under air at normal atmospheric pressure have been examined. Comparison of Raman peak positions of tetragonal and monoclinic zirconia phases, recorded during the oxide growth at elevated temperature, and after cooling at room temperature have been presented. Subsequently, Raman peak positions (or shifts) were interpreted in relation with the stress evolution in the growing zirconia scale, especially closed to the metal/oxide interface, where the influence of compressive stress in the oxide is the biggest. Reported results, for the first time show the presence of a continuous layer of tetragonal zirconia phase developed in the proximity of pure zirconium substrate. Based on the Raman peak positions we prove that this tetragonal layer is stabilized by the high compressive stress and sub-stoichiometry level. Presence of the tetragonal phase located in the outer part of the scale have been confirmed, yet its Raman characteristics suggest a stress-free tetragonal phase, therefore different type of stabilization mechanism. Presented study suggest that its stabilization could be related to the lattice defects introduced by highstoichiometry of zirconia or presence of heterovalent cations.

  6. Extracting mechanical properties of copper coatings on oxidized silicon substrates by nanoindentation

    NASA Astrophysics Data System (ADS)

    Moharrami, N.; Oila, A.; Bull, S. J.

    2014-08-01

    The thickness of the copper coatings that are used for the manufacture of conducting tracks in microelectronic devices are being aggressively scaled down and there is a need to monitor the mechanical response of metallization at a scale comparable to the material microstructure. When using indentation tests to assess the properties of thin films, the plastic zone dimensions are of a similar scale to the grain size. For the purposes of designs based on continuum mechanics approaches it is usually required that the grain size is much smaller than the deforming volume, which is not always observed in practice. Considerable differences between predicted and observed performance can be seen depending on the material tested and its grain size; the extent of oxidation of the copper after deposition is critical, as is that of its underlying silicon substrate. Whereas it is possible to make good measurements of metallization properties on stiff substrates such as silicon there are serious issues with the reliability of Young's modulus and hardness data from coatings on device quality wafers which may have been oxidized prior to use. The effects of grain size, shape and orientation on the mechanical response of metallic thin films used for semiconductor metallization on oxidized silicon are presented in this paper. The appropriate conditions for the successful use of continuum mechanics are discussed and the importance of considering the consequences of crystallographic anisotropy and oxidation on the selection of suitable design data is presented with regards to copper coatings.

  7. Biochemical Competition Makes Fatty-Acid β-Oxidation Vulnerable to Substrate Overload

    PubMed Central

    van Eunen, Karen; Simons, Sereh M. J.; Gerding, Albert; Bleeker, Aycha; den Besten, Gijs; Touw, Catharina M. L.; Houten, Sander M.; Groen, Bert K.; Krab, Klaas; Reijngoud, Dirk-Jan; Bakker, Barbara M.

    2013-01-01

    Fatty-acid metabolism plays a key role in acquired and inborn metabolic diseases. To obtain insight into the network dynamics of fatty-acid β-oxidation, we constructed a detailed computational model of the pathway and subjected it to a fat overload condition. The model contains reversible and saturable enzyme-kinetic equations and experimentally determined parameters for rat-liver enzymes. It was validated by adding palmitoyl CoA or palmitoyl carnitine to isolated rat-liver mitochondria: without refitting of measured parameters, the model correctly predicted the β-oxidation flux as well as the time profiles of most acyl-carnitine concentrations. Subsequently, we simulated the condition of obesity by increasing the palmitoyl-CoA concentration. At a high concentration of palmitoyl CoA the β-oxidation became overloaded: the flux dropped and metabolites accumulated. This behavior originated from the competition between acyl CoAs of different chain lengths for a set of acyl-CoA dehydrogenases with overlapping substrate specificity. This effectively induced competitive feedforward inhibition and thereby led to accumulation of CoA-ester intermediates and depletion of free CoA (CoASH). The mitochondrial [NAD+]/[NADH] ratio modulated the sensitivity to substrate overload, revealing a tight interplay between regulation of β-oxidation and mitochondrial respiration. PMID:23966849

  8. Metal Catalyst for Low-Temperature Growth of Controlled Zinc Oxide Nanowires on Arbitrary Substrates

    PubMed Central

    Kim, Baek Hyun; Kwon, Jae W.

    2014-01-01

    Zinc oxide nanowires generated by hydrothermal method present superior physical and chemical characteristics. Quality control of the growth has been very challenging and controlled growth is only achievable under very limited conditions using homogeneous seed layers with high temperature processes. Here we show the controlled ZnO nanowire growth on various organic and inorganic materials without the requirement of a homogeneous seed layer and a high temperature process. We also report the discovery of an important role of the electronegativity in the nanowire growth on arbitrary substrates. Using heterogeneous metal oxide interlayers with low-temperature hydrothermal methods, we demonstrate well-controlled ZnO nanowire arrays and single nanowires on flat or curved surfaces. A metal catalyst and heterogeneous metal oxide interlayers are found to determine lattice-match with ZnO and to largely influence the controlled alignment. These findings will contribute to the development of novel nanodevices using controlled nanowires. PMID:24625584

  9. Oxidation resistant high temperature thermal cycling resistant coatings on silicon-based substrates and process for the production thereof

    DOEpatents

    Sarin, V.K.

    1990-08-21

    An oxidation resistant, high temperature thermal cycling resistant coated ceramic article for ceramic heat engine applications is disclosed. The substrate is a silicon-based material, i.e. a silicon nitride- or silicon carbide-based monolithic or composite material. The coating is a graded coating of at least two layers: an intermediate AlN or Al[sub x]N[sub y]O[sub z] layer and an aluminum oxide or zirconium oxide outer layer. The composition of the coating changes gradually from that of the substrate to that of the AlN or Al[sub x]N[sub y]O[sub z] layer and further to the composition of the aluminum oxide or zirconium oxide outer layer. Other layers may be deposited over the aluminum oxide layer. A CVD process for depositing the graded coating on the substrate is also disclosed.

  10. Oxidation resistant high temperature thermal cycling resistant coatings on silicon-based substrates and process for the production thereof

    DOEpatents

    Sarin, Vinod K.

    1990-01-01

    An oxidation resistant, high temperature thermal cycling resistant coated ceramic article for ceramic heat engine applications. The substrate is a silicon-based material, i.e. a silicon nitride- or silicon carbide-based monolithic or composite material. The coating is a graded coating of at least two layers: an intermediate AlN or Al.sub.x N.sub.y O.sub.z layer and an aluminum oxide or zirconium oxide outer layer. The composition of the coating changes gradually from that of the substrate to that of the AlN or Al.sub.x N.sub.y O.sub.z layer and further to the composition of the aluminum oxide or zirconium oxide outer layer. Other layers may be deposited over the aluminum oxide layer. A CVD process for depositing the graded coating on the substrate is also disclosed.

  11. Enriched Iron(III)-Reducing Bacterial Communities are Shaped by Carbon Substrate and Iron Oxide Mineralogy

    PubMed Central

    Lentini, Christopher J.; Wankel, Scott D.; Hansel, Colleen M.

    2012-01-01

    Iron (Fe) oxides exist in a spectrum of structures in the environment, with ferrihydrite widely considered the most bioavailable phase. Yet, ferrihydrite is unstable and rapidly transforms to more crystalline Fe(III) oxides (e.g., goethite, hematite), which are poorly reduced by model dissimilatory Fe(III)-reducing microorganisms. This begs the question, what processes and microbial groups are responsible for reduction of crystalline Fe(III) oxides within sedimentary environments? Further, how do changes in Fe mineralogy shape oxide-hosted microbial populations? To address these questions, we conducted a large-scale cultivation effort using various Fe(III) oxides (ferrihydrite, goethite, hematite) and carbon substrates (glucose, lactate, acetate) along a dilution gradient to enrich for microbial populations capable of reducing Fe oxides spanning a wide range of crystallinities and reduction potentials. While carbon source was the most important variable shaping community composition within Fe(III)-reducing enrichments, both Fe oxide type and sediment dilution also had a substantial influence. For instance, with acetate as the carbon source, only ferrihydrite enrichments displayed a significant amount of Fe(III) reduction and the well-known dissimilatory metal reducer Geobacter sp. was the dominant organism enriched. In contrast, when glucose and lactate were provided, all three Fe oxides were reduced and reduction coincided with the presence of fermentative (e.g., Enterobacter spp.) and sulfate-reducing bacteria (e.g., Desulfovibrio spp.). Thus, changes in Fe oxide structure and resource availability may shift Fe(III)-reducing communities between dominantly metal-respiring to fermenting and/or sulfate-reducing organisms which are capable of reducing more recalcitrant Fe phases. These findings highlight the need for further targeted investigations into the composition and activity of speciation-directed metal-reducing populations within natural environments. PMID

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

    NASA Astrophysics Data System (ADS)

    Bara, Marek; Kubica, Marek

    2014-02-01

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

  13. Thermal oxidation-grown vanadium dioxide thin films on FTO (Fluorine-doped tin oxide) substrates

    NASA Astrophysics Data System (ADS)

    Tong, Guoxiang; Li, Yi; Wang, Feng; Huang, Yize; Fang, Baoying; Wang, Xiaohua; Zhu, Huiqun; Li, Liu; Shen, Yujian; Zheng, Qiuxin; Liang, Qian; Yan, Meng; Qin, Yuan; Ding, Jie

    2013-11-01

    By deposition of metallic vanadium on FTO substrate in Argon atmosphere at room temperature, the sample was then annealed in furnace for 2 h at the temperature of 410 °C in air ambient. (1 1 0) -orientated vanadium dioxide films were prepared on the FTO surface. A maximum transmittance of ˜40% happened at 900-1250 nm region at room temperature. The change of optical transmittance at this region was ˜25% between semiconducting and metallic states. In particular, vanadium dioxide thin films on FTO exhibit semiconductor-metal phase transition at ˜51 °C, the width of the hysteresis loop is ˜8 °C.

  14. Spinel-structured metal oxide on a substrate and method of making same by molecular beam epitaxy

    DOEpatents

    Chambers, Scott A.

    2006-02-21

    A method of making a spinel-structured metal oxide on a substrate by molecular beam epitaxy, comprising the step of supplying activated oxygen, a first metal atom flux, and at least one other metal atom flux to the surface of the substrate, wherein the metal atom fluxes are individually controlled at the substrate so as to grow the spinel-structured metal oxide on the substrate and the metal oxide is substantially in a thermodynamically stable state during the growth of the metal oxide. A particular embodiment of the present invention encompasses a method of making a spinel-structured binary ferrite, including Co ferrite, without the need of a post-growth anneal to obtain the desired equilibrium state.

  15. Stoichiometry of Proton Translocation Coupled to Substrate Oxidation in Plant Mitochondria

    PubMed Central

    Moreau, François; de Virville, Jacques Davy

    1985-01-01

    The proton translocation coupled to the electron flux from succinate, exogenous NADH, and NAD+-linked substrates (malate and isocitrate) to cytochrome c and to oxygen was studied in purified potato (Solanum tuberosum) mitochondria using oxygen and ferricyanide pulse techniques. In the presence of valinomycin plus K+ (used as a charge compensating cation), optimum values of H+/2 e− were obtained when low amounts of electron acceptors (oxygen or ferricyanide) were added to the mitochondria (1-2 nanogram [2 e−] equivalents per milligram protein). The stoichiometry of proton translocation to electron flux was unaffected in the presence of N-ethylmaleimide, an inhibitor of the Pi/H+ symport. With succinate as substrate, H+/2 e− ratios were 4.0 ± 0.2 and 3.7 ± 0.3 with oxygen and ferricyanide as electron acceptors, respectively. With exogenous NADH, H+/2e− ratios were 4.1 ± 0.9 and 3.4 ± 0.2, respectively. The proton translocation coupled to the oxidation of NAD+-linked substrates (malate, isocitrate) was dependent upon the presence of adenylates (ADP, AMP, or ATP). For malate (+ glutamate) oxidation the observed H+/2 e− ratios were increased from 3.6 ± 2.2 to 6.5 ± 0.5 in the presence of 20 micromolar ADP. PMID:16663992

  16. Gaseous Oxidized Mercury Flux from Substrates Associated with Industrial Scale Gold Mining in Nevada, USA

    NASA Astrophysics Data System (ADS)

    Miller, M. B.

    2015-12-01

    Gaseous elemental and oxidized mercury (Hg) fluxes were measured in a laboratory setting from substrate materials derived from industrial-scale open pit gold mining operations in Nevada, USA. Mercury is present in these substrates at a range of concentrations (10 - 40000 ng g-1), predominantly of local geogenic origin in association with the mineralized gold ores, but altered and redistributed to a varying degree by subsequent ore extraction and processing operations, including deposition of Hg recently emitted to the atmosphere from large point sources on the mines. Waste rock, heap leach, and tailings material usually comprise the most extensive and Hg emission relevant substrate surfaces. All three of these material types were collected from active Nevada mine sites in 2010 for previous research, and have since been stored undisturbed at the University of Nevada, Reno. Gaseous elemental Hg (GEM) flux was previously measured from these materials under a variety of conditions, and was re-measured in this study, using Teflon® flux chambers and Tekran® 2537A automated ambient air analyzers. GEM flux from dry undisturbed materials was comparable between the two measurement periods. Gaseous oxidized Hg (GOM) flux from these materials was quantified using an active filter sampling method that consisted of polysulfone cation-exchange membranes deployed in conjunction with the GEM flux apparatus. Initial measurements conducted within greenhouse laboratory space indicate that in dry conditions GOM is deposited to relatively low Hg cap and leach materials, but may be emitted from the much higher Hg concentration tailings material.

  17. (110)-oriented indium tin oxide films grown on m- and r-plane sapphire substrates

    NASA Astrophysics Data System (ADS)

    Chern, Ming-Yau; Lu, Tso-Wen; Xu, Wei-Lun

    2015-04-01

    Indium tin oxide (ITO) thin films have been deposited by pulsed laser deposition on m-plane (100) and r-plane (012) sapphire substrates. For both substrates, the films were grown with their [110] direction perpendicular to the substrate planes under the conditions of high growth temperature and high oxygen pressure. Their in-plane epitaxial relations with the substrates were identified to be ITO[001] ∥ Al2O3[020] and \\text{ITO}[1\\bar{1}0]\\parallel \\text{Al}2\\text{O}3[001] for the m-plane substrate. For the r-plane substrate, two types of lattice matching were observed: one being \\text{ITO}[001]\\parallel \\text{Al}2\\text{O}3[2,1, - 1/2] and \\text{ITO}[1\\bar{1}0]\\parallel \\text{Al}2\\text{O}3[4/3, - 4/3,2/3], the other being \\text{ITO}[001]\\parallel \\text{Al}2\\text{O}3[1, - 1,1/2] and \\text{ITO}[1\\bar{1}0]/\\text{Al}2\\text{O}3[8/3,4/3, - 2/3]. The electrical properties were measured by the Hall effect and van der Pauw methods at room temperature. All of the samples have low electrical resistivity on the order of 3.0 × 10-4 Ω cm, high carrier concentration of about 2.5 × 1020 cm-3, and mobility ranging from 70 to 90 cm2 V-1 s-1.

  18. Influence of Substrate Complexity on the Diastereoselective Formation of Spiroiminodihydantoin and Guanidinohydantoin from Chromate Oxidation

    PubMed Central

    Gremaud, Julia N.; Martin, Brooke D.; Sugden, Kent D.

    2009-01-01

    Chromate is a human carcinogen with a poorly defined mechanism of DNA damage. In vitro and prokaryotic studies have shown that DNA damage may occur via the formation of the hydantoin lesions guanidinohydantoin (Gh) and spiroiminodihydantoin (Sp) from further oxidation of 8-oxo-7,8-dihydroguanine (8oxoG). The unusual structure of these lesions coupled with their enhanced mutagenicity make them attractive for study with regard to their role in chromate-induced cancer. We have studied the formation of Gh versus Sp and their associated diastereomers following oxidation by model Cr(V) complexes and from in situ chromate reduction by ascorbate and glutathione. Identification of the two optically assigned diastereomers of Sp (R-Sp, S-Sp) as well as the two diastereomers of Gh, (Gh1 and Gh2; not yet optically assigned) were carried out using increasingly sterically hindered substrates (nucleoside → ssDNA → dsDNA). Lesion formation and diastereomeric preference was found to be highly oxidant- and substrate-dependent. The Ir(IV) positive control showed a shift from near equal levels of Gh and Sp, and near equal levels of all four diastereomers in the nucleoside, to all Gh formation in dsDNA, with a 5-fold enhancement in Gh2 over Gh1. The two model Cr(V) complexes used in this study, Cr(V)-salen and Cr(V)-ehba, showed opposite trends going from nucleoside to dsDNA with Cr(V)-salen giving enhanced Sp formation (with mainly R-Sp formed) and the Cr(V)-ehba having an oxidation profile nearly identical to that of Ir(IV). The two chromate reduction systems, Cr6+/ascorbate and Cr6+/glutathione, designed to model the intracellular reduction of chromate, showed lower levels of oxidation in all substrates. Notable in this group was the shift in the formation of the lesions to essentially all Sp for the Cr6+/ascorbate system with the most sterically hindered substrate, dsDNA. These results, when coupled with the known diastereomeric preference for excision of hydantoin lesions by

  19. Oxidization without substrate unfolding triggers proteolysis of the peroxide-sensor, PerR.

    PubMed

    Ahn, Bo-Eun; Baker, Tania A

    2016-01-01

    Peroxide operon regulator (PerR) is a broadly conserved hydrogen peroxide sensor in bacteria, and oxidation of PerR at its regulatory metal-binding site is considered irreversible. Here, we tested whether this oxidation specifically targets PerR for proteolysis. We find that oxidizing conditions stimulate PerR degradation in vivo, and LonA is the principal AAA+ (ATPases associated with diverse cellular activities) protease that degrades PerR. Degradation of PerR by LonA is recapitulated in vitro, and biochemical dissection of this degradation reveals that the presence of regulatory metal and PerR-binding DNA dramatically extends the half-life of the protein. We identified a LonA-recognition site critical for oxidation-controlled PerR turnover. Key residues for LonA-interaction are exposed to solvent in PerR lacking metal, but are buried in the metal-bound form. Furthermore, one residue critical for Lon recognition is also essential for specific DNA-binding by PerR, thus explaining how both the metal and DNA ligands prevent PerR degradation. This ligand-controlled allosteric mechanism for protease recognition provides a compelling explanation for how the oxidation-induced conformational change in PerR triggers degradation. Interestingly, the critical residues recognized by LonA and exposed by oxidation do not function as a degron, because they are not sufficient to convert a nonsubstrate protein into a LonA substrate. Rather, these residues are a conformation-discriminator sequence, which must work together with other residues in PerR to evoke efficient degradation. This mechanism provides a useful example of how other proteins with only mild or localized oxidative damage can be targeted for degradation without the need for extensive oxidation-dependent protein denaturation. PMID:26677871

  20. The crystallinity and mechanical properties of indium tin oxide coatings on polymer substrates

    SciTech Connect

    Kim, Eun-Hye; Yang, Chan-Woo; Park, Jin-Woo

    2011-02-15

    We present the relationship between the microstructure and mechanical strength of indium tin oxide (ITO) on flexible substrates. With varying thickness (h{sub f}), ITO is deposited on polyethylene terephthalate (PET) by dc magnetron sputtering. The microstructure of ITO is controlled by substrate surface conditions and sputtering parameters. The maximum substrate temperature during deposition is limited to 80 deg. C due to the low glass transition temperature (T{sub g}) of PET. The crystallinity and surface roughness (R{sub rms}) are analyzed by high resolution x-ray diffraction, high resolution transmission electron microscopy, and AFM. The crack resistance of ITO is evaluated by uniaxial tension test. The experimental results reveal that, at a fixed h{sub f}, the degree and quality of crystallinity of ITO are highly improved by increasing sputtering power and the substrate temperature. As the crystallinity is improved, the ratio of preferred growth orientations of (222) to (400) is increased and the degree of peak shifts to lower 2{theta} is decreased. They indicate that the crystallinity is improved as the lattice damage is reduced and film density is increased. The tension test results confirm that, up to a certain h{sub f}, the strength of ITO can be significantly enhanced by improving the microstructures.

  1. The crystallinity and mechanical properties of indium tin oxide coatings on polymer substrates

    NASA Astrophysics Data System (ADS)

    Kim, Eun-Hye; Yang, Chan-Woo; Park, Jin-Woo

    2011-02-01

    We present the relationship between the microstructure and mechanical strength of indium tin oxide (ITO) on flexible substrates. With varying thickness (hf), ITO is deposited on polyethylene terephthalate (PET) by dc magnetron sputtering. The microstructure of ITO is controlled by substrate surface conditions and sputtering parameters. The maximum substrate temperature during deposition is limited to 80 °C due to the low glass transition temperature (Tg) of PET. The crystallinity and surface roughness (Rrms) are analyzed by high resolution x-ray diffraction, high resolution transmission electron microscopy, and AFM. The crack resistance of ITO is evaluated by uniaxial tension test. The experimental results reveal that, at a fixed hf, the degree and quality of crystallinity of ITO are highly improved by increasing sputtering power and the substrate temperature. As the crystallinity is improved, the ratio of preferred growth orientations of (222) to (400) is increased and the degree of peak shifts to lower 2θ is decreased. They indicate that the crystallinity is improved as the lattice damage is reduced and film density is increased. The tension test results confirm that, up to a certain hf, the strength of ITO can be significantly enhanced by improving the microstructures.

  2. Stretchable metal oxide thin film transistors on engineered substrate for electronic skin applications.

    PubMed

    Romeo, Alessia; Lacour, Stphanie P

    2015-08-01

    Electronic skins aim at providing distributed sensing and computation in a large-area and elastic membrane. Control and addressing of high-density soft sensors will be achieved when thin film transistor matrices are also integrated in the soft carrier substrate. Here, we report on the design, manufacturing and characterization of metal oxide thin film transistors on these stretchable substrates. The TFTs are integrated onto an engineered silicone substrate with embedded strain relief to protect the devices from catastrophic cracking. The TFT stack is composed of an amorphous In-Ga-Zn-O active layer, a hybrid AlxOy/Parylene dielectric film, gold electrodes and interconnects. All layers are prepared and patterned with planar, low temperature and dry processing. We demonstrate the interconnected IGZO TFTs sustain applied tensile strain up to 20% without electrical degradation and mechanical fracture. Active devices are critical for distributed sensing. The compatibility of IGZO TFTs with soft and biocompatible substrates is an encouraging step towards wearable electronic skins. PMID:26738152

  3. Influence of organic substrates on the kinetics of bacterial As(III) oxidation

    NASA Astrophysics Data System (ADS)

    Lescure, T.; Joulian, C.; Bauda, P.; Hénault, C.; Battaglia-Brunet, F.

    2012-04-01

    Soil microflora plays a major role on the behavior of metals and metalloids. Arsenic speciation, in particular, is related to the activity of bacteria able to oxidize, reduce or methylate this element, and determines mobility, bioavailability and toxicity of As. Arsenite (AsIII) is more toxic and more mobile than arsenate (AsV). Bacterial As(III)-oxidation tends to reduce the toxicity of arsenic in soils and the risk of transfer toward underlying aquifers, that would affect the quality of water resources. Previous results suggest that organic matter may affect kinetics or efficiency of bacterial As(III)-oxidation in presence of oxygen, thus in conventional physico-chemical conditions of a surface soil. Different hypothesis can be proposed to explain the influence of organic matter on As(III) oxidation. Arsenic is a potential energy source for bacteria. The presence of easily biodegradable organic matter may inhibit the As(III) oxidation process because bacteria would first metabolize these more energetic substrates. A second hypothesis would be that, in presence of organic matter, the Ars system involved in bacterial resistance to arsenic would be more active and would compete with the Aio system of arsenite oxidation, decreasing the global As(III) oxidation rate. In addition, organic matter influences the solubility of iron oxides which often act as the main pitfalls of arsenic in soils. The concentration and nature of organic matter could therefore have a significant influence on the bioavailability of arsenic and hence on its environmental impact. The influence of organic matter on biological As(III) oxidation has not yet been determined in natural soils. In this context, soil amendment with organic matter during operations of phytostabilization or, considering diffuse pollutions, through agricultural practices, may affect the mobility and bio-availability of the toxic metalloid. The objective of the present project is to quantify the influence of organic matter

  4. Polypyrrole Coated Cellulosic Substrate Modified by Copper Oxide as Electrode for Nitrate Electroreduction

    NASA Astrophysics Data System (ADS)

    Hamam, A.; Oukil, D.; Dib, A.; Hammache, H.; Makhloufi, L.; Saidani, B.

    2015-08-01

    The aim of this work is to synthesize polypyrrole (PPy) films on nonconducting cellulosic substrate and modified by copper oxide particles for use in the nitrate electroreduction process. Firstly, the chemical polymerization of polypyrrole onto cellulosic substrate is conducted by using FeCl3 as an oxidant and pyrrole as monomer. The thickness and topography of the different PPy films obtained were estimated using a profilometer apparatus. The electrochemical reactivity of the obtained electrodes was tested by voltamperometry technique and electrochemical impedance spectroscopy. Secondly, the modification of the PPy film surface by incorporation of copper oxide particles is conducted by applying a galvanostatic procedure from a CuCl2 solution. The SEM, EDX and XRD analysis showed the presence of CuO particles in the polymer films with dimensions less than 50 nm. From cyclic voltamperometry experiments, the composite activity for the nitrate electroreduction reaction was evaluated and the peak of nitrate reduction is found to vary linearly with initial nitrate concentration.

  5. Fabrication of a substrate-independent aluminum oxide-GaAs distributed Bragg reflector

    SciTech Connect

    Wohlert, D.E.; Lin, H.C.; Chang, K.L.; Pickrell, G.W. Jr.; Epple, J.H.; Hsieh, K.C.; Cheng, K.Y. )

    1999-09-01

    We propose a method for forming a top distributed Bragg reflector (DBR) during very-low temperature (VLT) molecular-beam epitaxy (MBE) growth that is independent of the substrate being used. By varying the arsenic overpressure during VLT MBE, it was determined by Auger electron spectroscopy and cross-section transmission electron microscopy that alternating layers of polycrystalline GaAs and amorphous (Al,As) can be deposited. Because these layers are not single crystal, they can be grown on any host lattice. After lateral wet oxidation, the polycrystalline GaAs does not undergo any significant changes; whereas the amorphous (Al,As) becomes an amorphous aluminum oxide. An index step of [Delta]n=1.88 is realized between these two layers which makes it possible to fabricate a high efficiency DBR with very few polycrystal-GaAs/amorphous-Al-oxide pairs on GaAs-, GaP-, or InP-based materials. Using reflectivity measurements, we demonstrate a five pair GaAs/AlAs-based DBR grown on an InP substrate that reflects wavelengths between 1.4 and 2.3 [mu]m up to 95[percent]. [copyright] [ital 1999 American Institute of Physics.

  6. Hydrogen peroxide generation by higher plant mitochondria oxidizing complex I or complex II substrates.

    PubMed

    Braidot, E; Petrussa, E; Vianello, A; Macri, F

    1999-05-28

    The generation of H2O2 by isolated pea stem mitochondria, oxidizing either malate plus glutamate or succinate, was examined. The level of H2O2 was almost one order of magnitude higher when mitochondria were energized by succinate. The succinate-dependent H2O2 formation was abolished by malonate, but unaffected by rotenone. The lack of effect of the latter suggests that pea mitochondria were working with a proton motive force below the threshold value required for reverse electron transfer. The activation by pyruvate of the alternative oxidase was reflected in an inhibition of H2O2 formation. This effect was stronger when pea mitochondria oxidized malate plus glutamate. Succinate-dependent H2O2 formation was ca. four times lower in Arum sp. mitochondria (known to have a high alternative oxidase) than in pea mitochondria. An uncoupler (FCCP) completely prevented succinate-dependent H2O2 generation, while it only partially (40-50%) inhibited that linked to malate plus glutamate. ADP plus inorganic phosphate (transition from state 4 to state 3) also inhibited the succinate-dependent H2O2 formation. Conversely, that dependent on malate plus glutamate oxidation was unaffected by low and stimulated by high concentrations of ADP. These results show that the main bulk of H2O2 is formed during substrate oxidation at the level of complex II and that this generation may be prevented by either dissipation of the electrochemical proton gradient (uncoupling and transition state 4-state 3), or preventing its formation (alternative oxidase). Conversely, H2O2 production, dependent on oxidation of complex I substrate, is mainly lowered by the activation of the alternative oxidase. PMID:10371218

  7. Electrophoretic deposition of graphene oxide reinforced chitosan-hydroxyapatite nanocomposite coatings on Ti substrate.

    PubMed

    Shi, Y Y; Li, M; Liu, Q; Jia, Z J; Xu, X C; Cheng, Y; Zheng, Y F

    2016-03-01

    Electrophoretic deposition (EPD) is a facile and feasible technique to prepare functional nanocomposite coatings for application in orthopedic-related implants. In this work, a ternary graphene oxide-chitosan-hydroxyapatite (GO-CS-HA) composite coating on Ti substrate was successfully fabricated by EPD. Coating microstructure and morphologies were investigated by scanning electron microscopy, contact angle test, Raman spectroscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. It was found GO-CS surface were uniformly decorated by HA nanoparticles. The potentiodynamic polarization test in simulated body fluid indicated that the GO-CS-HA coatings could provide effective protection of Ti substrate from corrosion. This ternary composite coating also exhibited good biocompatibility during incubation with MG63 cells. In addition, the nanocomposite coatings could decrease the attachment of Staphylococcus aureus. PMID:26758895

  8. Cerium oxide layers on the Cu(1 1 1) surface: Substrate-mediated redox properties

    NASA Astrophysics Data System (ADS)

    Wrobel, R.; Suchorski, Y.; Becker, S.; Weiss, H.

    Ceria submonolayers consisting of nanosized 2D islands on a Cu(1 1 1) surface have been prepared by oxidation of the nucleating Ce submonolayer (0.7 ML) and characterized using XPS and STM. The reducibility of the resulting well-defined CeO 2-x/Cu(1 1 1) model system of the "inverse supported catalyst" type was studied by XPS using CO as reducing agent. In order to investigate the contribution of the substrate in the redox process, the properties of a ceria submonolayer (0.7 ML) on Cu(1 1 1), of an optically dense layer of ceria (1.5 ML) on Cu(1 1 1) and of a ceria submonolayer (0.7 ML) on Pt(1 1 1) have been compared. The direct comparison reveals the (metal substrate mediated) spillover mechanism of the ceria reduction by CO in the present CeO 2-x/Me fcc(1 1 1) model systems.

  9. Tailored surfaces of perovskite oxide substrates for conducted growth of thin films.

    PubMed

    Sánchez, Florencio; Ocal, Carmen; Fontcuberta, Josep

    2014-04-01

    Oxide electronics relies on the availability of epitaxial oxide thin films. The extreme flexibility of the chemical composition of ABO3 perovskites and the broad spectrum of properties they cover, inspire the creativity of scientists and place perovskites in the lead of functional materials for advanced technologies. Moreover, emerging properties are being discovered at interfaces between distinct perovskites that could not be anticipated on the basis of those of the adjacent epitaxial layers. All dreamed new prospects require the use of suitable substrates for epitaxial growth. Perovskite single crystals are the workhorses of this activity and understanding and controlling their surface properties have become critical. In this tutorial review we will chiefly focus on the impact of the morphology and composition of the surface of ABO3 perovskite substrates on the growth mechanisms and properties of thin films epitaxially grown on them. As SrTiO3 is the most popular substrate, we will mostly concentrate on describing the current understanding and achievements for it. Illustrative examples of other perovskite substrates (LaAlO3, LSAT and DyScO3) will be also included. We will show that distinct chemical terminations can exist on the surfaces used for growth and we will review methods employed either to select the most appropriate one for specific growth to allow, for instance, tailoring the ultimate outmost epilayer, or to induce self-ordering to engineer long-range nanoscale patterns of chemical terminations. We will demonstrate the capacity of this knowledge by the growth of low-dimensional organic and inorganic structures. PMID:24553667

  10. Electrical and optical properties of pyrolytically electrostatic sprayed fluorine-doped tin-oxide: Dependence on substrate-temperature and substrate-nozzle distance

    NASA Astrophysics Data System (ADS)

    Zaouk, D.; Zaatar, Y.; Khoury, A.; Llinares, C.; Charles, J.-P.; Bechara, J.

    2000-05-01

    Tin-oxide (SnO2) thin films were prepared by a modified spray technique called electrostatic spray pyrolysis. Their electrical and optical properties dependence on fluorine concentration, substrate temperature Ts, and the substrate-nozzle distance Dsn was studied. Dsn and Ts seem to be interrelated for the optimization of good quality fluorine-doped SnO2 films. Films of about 9×10-4 Ω cm resistivity and high visible 85% transparency were obtained for a substrate temperature of 550 °C, a 6 cm substrate nozzle distance, and 80% of hydrofluorhydric acid HF in the starting solution. These data are discussed in light of the kinetics reaction.

  11. Elemental Metals or Oxides Distributed on a Carbon Substrate or Self-Supported and the Manufacturing Process Using Graphite Oxide as Template

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Chen (Inventor)

    1999-01-01

    A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a percursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon, metal, chloride, and oxygen. This intermediary product can be further processed by direct exposure to carbonate solutions to form a second intermediary product comprising carbon, metal carbonate, and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide; b) in an inert environment to produce metal oxide on carbon substrate; c) in a reducing environment to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

  12. Elemental Metals or Oxides Distributed on a Carbon Substrate or Self-Supported and the Manufacturing Process Using Graphite Oxide as Template

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh (Inventor)

    1999-01-01

    A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a precursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon, metal, chloride, and oxygen. This intermediary product can be further processed by direct exposure to carbonate-solutions to form a second intermediary product comprising carbon, metal carbonate, and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide; b) in an inert environment to produce metal oxide on carbon substrate; c) in a reducing environment to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

  13. Substrate oxidation capacity in rodent skeletal muscle: effects of exposure to zero gravity

    NASA Technical Reports Server (NTRS)

    Baldwin, K. M.; Herrick, R. E.; McCue, S. A.

    1993-01-01

    A study was conducted, as part of the integrated National Aeronautics and Space Administration Space Life Sciences 1 mission flown in June of 1991, to ascertain the effects of 9 days of exposure to zero gravity on the capacity of rodent skeletal muscle fiber types to oxidize either [14C]pyruvate or [14C]palmitate under state 3 metabolic conditions, i.e., nonlimiting amounts of substrate and cofactors. In addition, activity levels of marker enzymes of the tricarboxylic acid cycle, malate shuttle, and beta-oxidation were measured. Results showed that significant differences in muscle weight occurred in both the predominantly slow vastus intermedius and predominantly fast vastus lateralis of flight vs. control groups (P < 0.05). Total protein content of the muscle samples was similar between groups. Both pyruvate oxidation capacity and the marker oxidative enzymes were not altered in the flight relative to control animals. However, the capacity to oxidize long-chain fatty acids was significantly reduced by 37% in both the high- and low-oxidative regions of the vastus muscle (P < 0.05). Although these findings of a selective reduction in fatty acid oxidation capacity in response to spaceflight are surprising, they are consistent with previous findings showing 1) an increased capacity to take up glucose and upregulate glucose transporter proteins and 2) a marked accumulation of triglycerides in the skeletal muscles of rats subjected to states of unloading. Thus, skeletal muscle of animals exposed to non-weight-bearing environments undergo subcellular transformations that may preferentially bias energy utilization to carbohydrates.

  14. Crystal Structure of Oxidative Stress Sensor Keap1 in Complex with Selective Autophagy Substrate p62

    NASA Astrophysics Data System (ADS)

    Kurokawa, Hirofumi

    Keap1, an adaptor protein of cullin-RING ubiquitin ligase complex, represses cytoprotective transcription factor Nrf2 in an oxidative stress-dependent manner. The accumulation of selective autophagy substrate p62 also activates Nrf2 target genes, but the detailed mechanism has not been elucidated. Crystal structure of Keap1-p62 complex revealed the structural basis for the Nrf2 activation in which Keap1 is inactivated by p62. The accumulation of p62 is observed in hepatocellular carcinoma. The activation of Nrf2 target genes, including detoxifying enzymes and efflux transporters, by p62 may protect the cancer cells from anti-cancer drugs.

  15. Transparent conductive indium oxide film deposited on low temperature substrates by activated reactive evaporation.

    PubMed

    Marcovitch, O; Klein, Z; Lubezky, I

    1989-07-15

    High quality conductive coatings for the visible region were prepared on low temperature glass substrates. The conductive layer was an indium oxide film deposited by the activated reactive evaporation technique using a glow discharge hollow cathode ion gun. An antireflective layer of MgF(2) was deposited over the conductive layer. The average transmission in the visible region of the coated glass with sheet resistance of < 15 Omega/sq was greater than 90%. The coating was durable and passed a series of environmental tests according to MIL-C-675C. PMID:20555600

  16. Effects of substrates on N2O emissions in an anaerobic ammonium oxidation (anammox) reactor.

    PubMed

    Jin, Yue; Wang, Dunqiu; Zhang, Wenjie

    2016-01-01

    N2O emission in the anaerobic ammonium oxidation (anammox) process is of growing concern. In this study, effects of substrate concentrations on N2O emissions were investigated in an anammox reactor. Extremely high N2O emissions of 1.67 % were led by high NH4-N concentrations. Results showed that N2O emissions have a positive correlation with NH4-N concentrations in the anammox reactor. Reducing NH4-N concentrations by recycling pump resulted in decreasing N2O emissions. In addition, further studies were performed to identify a key biological process that is contributed to N2O emissions from the anammox reactor. Based on the results obtained, Nitrosomonas, which can oxidize ammonia to nitrite, was deemed as the main sources of N2O emissions. PMID:27376009

  17. Graphdiyne oxides as excellent substrate for electroless deposition of Pd clusters with high catalytic activity.

    PubMed

    Qi, Hetong; Yu, Ping; Wang, Yuexiang; Han, Guangchao; Liu, Huibiao; Yi, Yuanping; Li, Yuliang; Mao, Lanqun

    2015-04-29

    Graphdiyne (GDY), a novel kind of two-dimensional carbon allotrope consisting of sp- and sp(2)-hybridized carbon atoms, is found to be able to serve as the reducing agent and stabilizer for electroless deposition of highly dispersed Pd nanoparticles owing to its low reduction potential and highly conjugated electronic structure. Furthermore, we observe that graphdiyne oxide (GDYO), the oxidation form of GDY, can be used as an even excellent substrate for electroless deposition of ultrafine Pd clusters to form Pd/GDYO nanocomposite that exhibits a high catalytic performance toward the reduction of 4-nitrophenol. The high catalytic performance is considered to benefit from the rational design and electroless deposition of active metal catalysts with GDYO as the support. PMID:25871853

  18. Alkylamine-Dependent Amino-Acid Oxidation by Lysine Monooxygenase—Fragmented Substrate of Oxygenase

    PubMed Central

    Yamamoto, Shozo; Yamauchi, Takashi; Hayaishi, Osamu

    1972-01-01

    Lysine monooxygenase catalyzes the oxygenative decarboxylation of L-lysine and produces a corresponding acid amide. L-Alanine was inactive as substrate. However, when propylamine was present, oxidation, but not oxygenation, of alanine was demonstrated with the oxygenase. Alanine was converted to pyruvate, with the liberation of ammonia and hydrogen peroxide, but propylamine remained unchanged. Other α-monoamino acids were also oxidized in the presence of alkylamines with various carbon chain lengths. The highest oxidase activity was observed when the total chain length of both amino acid and amine was nearly identical with that of lysine. Available evidence indicates that the amine-dependent amino-acid oxidase activity is associated with the lysine oxygenase activity. PMID:4509334

  19. Cytochrome P450-like substrate oxidation catalyzed by cytochrome c and immobilized cytochrome c.

    PubMed

    Akasaka, R; Mashino, T; Hirobe, M

    1993-03-01

    Cytochrome c (cyt.c) was shown to catalyze cytochrome P450 (P450)-like oxidative reactions, such as N-, and O-demethylation, S-oxidation, and epoxidation of olefins. A more detailed examination showed that (i) N-methylcarbazole and thioanisole oxidation with H2(18)O2 catalyzed by cyt.c resulted in introduction of 18O into the product, and (ii) during the epoxidation of cis-stilbene catalyzed by cyt.c, the stereochemistry of the substrate was retained and 18O was introduced when H2(18)O2 was used as an oxidant. These results show that cyt.c catalyzed N-demethylation, S-oxidation, and epoxidation in the same manner as P450. To utilize these P450-like reactivities effectively, cyt.c was immobilized on poly-gamma-methyl-L-glutamate. Up to 99% of the cyt.c used was immobilized. This immobilized cyt.c catalyzed N-demethylation, S-oxidation, and epoxidation in the same manner as both P450 and free cyt.c, and the activities of these reactions were increased by the immobilization. In N-demethylation of N,N-dimethylaniline with cumene hydroperoxide (CHP) catalyzed by cyt.c, the Vmax for CHP was increased by 4.4-fold by the immobilization of the enzyme, while the Km remained unchanged. Since P450 is involved in the metabolism of many xenobiotics, the above results suggest that immobilized cyt.c may be useful in drug metabolism research. PMID:7681661

  20. Gate stack dielectric degradation of rare-earth oxides grown on high mobility Ge substrates

    NASA Astrophysics Data System (ADS)

    Shahinur Rahman, Md.; Evangelou, E. K.; Konofaos, N.; Dimoulas, A.

    2012-11-01

    We report on the reliability characteristics and their analysis, of rare-earth oxides (REOs) dielectric degradation, when used as interfacial buffer layers together with HfO2 high-k films (REOs/HfO2) on high mobility Ge substrates. Metal-oxide-semiconductor (MOS) devices with these stacks, show dissimilar charge trapping phenomena under varying levels of constant-voltage-stress (CVS) conditions, influencing the measured densities of the interface (Nit) and border (NBT) traps. In the present study, we report on C-Vg hysteresis curves related to both Nit and NBT. We propose a new model based on the Maxwell-Wagner mechanism, and this model explains the current decay transient observed under CVS bias from low to higher fields of MOS gate stack devices grown on Ge substrates. The proposed model is unlike to those used for other MOS devices. Finally, CVS measurements for very long times at moderate fields reveal an initial current decay due to relaxation, followed by charge trapping and generation of stress-induced leakage which eventually lead to hard breakdown.

  1. Synthesis of reduced graphene oxide/ZnO nanorods composites on graphene coated PET flexible substrates

    SciTech Connect

    Huang, Lei Guo, Guilue; Liu, Yang; Chang, Quanhong; Shi, Wangzhou

    2013-10-15

    Graphical abstract: - Highlights: • ZnO nanorods synthesized on CVD-graphene and rGO surfaces, respectively. • ZnO/CVD-graphene and ZnO/rGO form a distinctive porous 3D structure. • rGO/ZnO nanostructures possibility in energy storage devices. - Abstract: In this work, reduced graphene oxide (rGO)/ZnO nanorods composites were synthesized on graphene coated PET flexible substrates. Both chemical vapor deposition (CVD) graphene and reduced graphene oxide (rGO) films were prepared following by hydrothermal growth of vertical aligned ZnO nanorods. Reduced graphene sheets were then spun coated on the ZnO materials to form a three dimensional (3D) porous nanostructure. The morphologies of the ZnO/CVD graphene and ZnO/rGO were investigated by SEM, which shows that the ZnO nanorods grown on rGO are larger in diameters and have lower density compared with those grown on CVD graphene substrate. As a result of fact, the rough surface of nano-scale ZnO on rGO film allows rGO droplets to seep into the large voids of ZnO nanorods, then to form the rGO/ZnO hierarchical structure. By comparison of the different results, we conclude that rGO/ZnO 3D nanostructure is more desirable for the application of energy storage devices.

  2. Reduced Graphene Oxide Thin Film on Conductive Substrates by Bipolar Electrochemistry

    NASA Astrophysics Data System (ADS)

    Anis, Allagui; Mohammad, Ali Abdelkareem; Hussain, Alawadhi; Ahmed, S. Elwakil

    2016-02-01

    Recent years have shown an increased interest in developing manufacturing processes for graphene and its derivatives that consider the environmental impact and large scale cost-effectiveness. However, today’s most commonly used synthesis routes still suffer from their excessive use of harsh chemicals and/or the complexity and financial cost of the process. Furthermore, the subsequent transfer of the material onto a substrate makes the overall process even more intricate and time-consuming. Here we describe a single-step, single-cell preparation procedure of metal-supported reduced graphene oxide (rGO) using the principle of bipolar electrochemistry of graphite in deionized water. Under the effect of an electric field between two stainless steel feeder electrodes, grapheme layers at the anodic pole of the wireless graphite were oxidized into colloidal dispersion of GO, which migrated electrophoretically towards the anodic side of the cell, and deposited in the form of rGO (d(002) = 0.395 nm) by van der Waals forces. For substrates chemically more susceptible to the high anodic voltage, we show that the electrochemical setup can be adapted by placing the latter between the wireless graphite and the stainless steel feeder anode. This method is straightforward, inexpensive, environmentally-friendly, and could be easily scaled up for high yield and large area production of rGO thin films.

  3. Reduced Graphene Oxide Thin Film on Conductive Substrates by Bipolar Electrochemistry.

    PubMed

    Anis, Allagui; Mohammad, Ali Abdelkareem; Hussain, Alawadhi; Ahmed, S Elwakil

    2016-01-01

    Recent years have shown an increased interest in developing manufacturing processes for graphene and its derivatives that consider the environmental impact and large scale cost-effectiveness. However, today's most commonly used synthesis routes still suffer from their excessive use of harsh chemicals and/or the complexity and financial cost of the process. Furthermore, the subsequent transfer of the material onto a substrate makes the overall process even more intricate and time-consuming. Here we describe a single-step, single-cell preparation procedure of metal-supported reduced graphene oxide (rGO) using the principle of bipolar electrochemistry of graphite in deionized water. Under the effect of an electric field between two stainless steel feeder electrodes, grapheme layers at the anodic pole of the wireless graphite were oxidized into colloidal dispersion of GO, which migrated electrophoretically towards the anodic side of the cell, and deposited in the form of rGO (d(002) = 0.395 nm) by van der Waals forces. For substrates chemically more susceptible to the high anodic voltage, we show that the electrochemical setup can be adapted by placing the latter between the wireless graphite and the stainless steel feeder anode. This method is straightforward, inexpensive, environmentally-friendly, and could be easily scaled up for high yield and large area production of rGO thin films. PMID:26883173

  4. Reduced Graphene Oxide Thin Film on Conductive Substrates by Bipolar Electrochemistry

    PubMed Central

    Anis, Allagui; Mohammad, Ali Abdelkareem; Hussain, Alawadhi; Ahmed, S. Elwakil

    2016-01-01

    Recent years have shown an increased interest in developing manufacturing processes for graphene and its derivatives that consider the environmental impact and large scale cost-effectiveness. However, today’s most commonly used synthesis routes still suffer from their excessive use of harsh chemicals and/or the complexity and financial cost of the process. Furthermore, the subsequent transfer of the material onto a substrate makes the overall process even more intricate and time-consuming. Here we describe a single-step, single-cell preparation procedure of metal-supported reduced graphene oxide (rGO) using the principle of bipolar electrochemistry of graphite in deionized water. Under the effect of an electric field between two stainless steel feeder electrodes, grapheme layers at the anodic pole of the wireless graphite were oxidized into colloidal dispersion of GO, which migrated electrophoretically towards the anodic side of the cell, and deposited in the form of rGO (d(002) = 0.395 nm) by van der Waals forces. For substrates chemically more susceptible to the high anodic voltage, we show that the electrochemical setup can be adapted by placing the latter between the wireless graphite and the stainless steel feeder anode. This method is straightforward, inexpensive, environmentally-friendly, and could be easily scaled up for high yield and large area production of rGO thin films. PMID:26883173

  5. Designing interlayers to improve the mechanical reliability of transparent conductive oxide coatings on flexible substrates

    SciTech Connect

    Kim, Eun-Hye; Yang, Chan-Woo; Park, Jin-Woo

    2012-05-01

    In this study, we investigate the effect of interlayers on the mechanical properties of transparent conductive oxide (TCO) on flexible polymer substrates. Indium tin oxide (ITO), which is the most widely used TCO film, and Ti, which is the most widely used adhesive interlayer, are selected as the coating and the interlayer, respectively. These films are deposited on the polymer substrates using dc-magnetron sputtering to achieve varying thicknesses. The changes in the following critical factors for film cracking and delamination are analyzed: the internal stress ({sigma}{sup i}) induced in the coatings during deposition using a white light interferometer, the crystallinity using a transmission electron microscope, and the surface roughness of ITO caused by the interlayer using an atomic force microscope. The resistances to the cracking and delamination of ITO are evaluated using a fragmentation test. Our tests and analyses reveal the important role of the interlayers, which significantly reduce the compressive {sigma}{sup i} that is induced in the ITO and increase the resistance to the buckling delamination of the ITO. However, the relaxation of {sigma}{sup i} is not beneficial to cracking because there is less compensation for the external tension as {sigma}{sup i} further decreases. Based on these results, the microstructural control is revealed as a more influential factor than {sigma}{sup i} for improving crack resistance.

  6. Microstructural characteristics of tin oxide-based thin films on (0001) Al2O3 substrates: effects of substrate temperature and RF power during co-sputtering.

    PubMed

    Hwang, Sooyeon; Lee, Ju Ho; Kim, Young Yi; Yun, Myeong Goo; Lee, Kwan-Hun; Lee, Jeong Yong; Cho, Hyung Koun

    2014-12-01

    While tin oxides such as SnO and SnO2 are widely used in various applications, surprisingly, only a limited number of reports have been presented on the microstructural characteristics of tin oxide thin films grown under various growth conditions. In this paper, the effects of the substrate temperature and content of foreign Zn ion on the microstructural characteristics of tin oxide thin films grown by radio-frequency magnetron sputtering were investigated. The increase in substrate temperature induced change in the stoichiometry of the thin films from SnO(1+x) to SnO(2-x). Additionally, the phase contrast in the transmission electron microscopy image revealed that SnO(1+x) and SnO(2-x) phases were alternating in thin films and the width of each phase became narrower at high substrate temperature. The ternary zinc tin oxide thin films were deposited using the co-sputtering method. As the ZnO target power increased, the crystallinity of the thin films became poly-crystalline, and then showed improved crystallinity again with two types of phases. PMID:25970980

  7. Investigation into the role of NaCL deposited on oxide and metal substrates in the initiation of hot corrosion

    NASA Technical Reports Server (NTRS)

    Birks, N.

    1981-01-01

    The conversion to Na2SO4 of NaCl deposited on oxide substrates was studied as a function of temperature, in air with various SO2 and H2O partial pressures. The substrate was either a pure oxide or an oxide scale growing on a metal specimen. The progress of the reaction was observed using the SEM-EDAX technique to monitor morphological effects and, as far as possible, establish the rate of the process. The physical characteristics of the interaction between salt and substrate were also examined with particular reference to physical damage to the underlying oxide, especially when this is a scale on a metal specimen. An effort was also made to establish the conditions under which liquid phases may form and the mechanisms by which they form.

  8. Regulatory role for the arginine-nitric oxide pathway in metabolism of energy substrates.

    PubMed

    Jobgen, Wenjuan Shi; Fried, Susan K; Fu, Wenjiang J; Meininger, Cynthia J; Wu, Guoyao

    2006-09-01

    Nitric oxide (NO) is synthesized from L-arginine by NO synthase in virtually all cell types. Emerging evidence shows that NO regulates the metabolism of glucose, fatty acids and amino acids in mammals. As an oxidant, pathological levels of NO inhibit nearly all enzyme-catalyzed reactions through protein oxidation. However, as a signaling molecule, physiological levels of NO stimulate glucose uptake as well as glucose and fatty acid oxidation in skeletal muscle, heart, liver and adipose tissue; inhibit the synthesis of glucose, glycogen, and fat in target tissues (e.g., liver and adipose); and enhance lipolysis in adipocytes. Thus, an inhibition of NO synthesis causes hyperlipidemia and fat accretion in rats, whereas dietary arginine supplementation reduces fat mass in diabetic fatty rats. The putative underlying mechanisms may involve multiple cyclic guanosine-3',5'-monophosphate-dependent pathways. First, NO stimulates the phosphorylation of adenosine-3',5'-monophosphate-activated protein kinase, resulting in (1) a decreased level of malonyl-CoA via inhibition of acetyl-CoA carboxylase and activation of malonyl-CoA decarboxylase and (2) a decreased expression of genes related to lipogenesis and gluconeogenesis (glycerol-3-phosphate acyltransferase, sterol regulatory element binding protein-1c and phosphoenolpyruvate carboxykinase). Second, NO increases the phosphorylation of hormone-sensitive lipase and perilipins, leading to the translocation of the lipase to the neutral lipid droplets and, hence, the stimulation of lipolysis. Third, NO activates expression of peroxisome proliferator-activated receptor-gamma coactivator-1alpha, thereby enhancing mitochondrial biogenesis and oxidative phosphorylation. Fourth, NO increases blood flow to insulin-sensitive tissues, promoting substrate uptake and product removal via the circulation. Modulation of the arginine-NO pathway through dietary supplementation with L-arginine or L-citrulline may aid in the prevention and

  9. Lipid oxidation in minced beef meat with added Krebs cycle substrates to stabilise colour.

    PubMed

    Yi, G; Grabež, V; Bjelanovic, M; Slinde, E; Olsen, K; Langsrud, O; Phung, V T; Haug, A; Oostindjer, M; Egelandsdal, B

    2015-11-15

    Krebs cycle substrates (KCS) can stabilise the colour of packaged meat by oxygen reduction. This study tested whether this reduction releases reactive oxygen species that may lead to lipid oxidation in minced meat under two different storage conditions. KCS combinations of succinate and glutamate increased peroxide forming potential (PFP, 1.18-1.32 mmol peroxides/kg mince) and thiobarbituric acid reactive substances (TBARS, 0.30-0.38 mg malondialdehyde (MDA) equivalents/kg mince) under low oxygen storage conditions. Both succinate and glutamate were metabolised. Moreover, under high oxygen (75%) storage conditions, KCS combinations of glutamate, citrate and malate increased PFP (from 1.22 to 1.29 mmol peroxides/kg) and TBARS (from 0.37 to 0.40 mg MDA equivalents/kg mince). Only glutamate was metabolised. The KCS combinations that were added to stabilise colour were metabolised during storage, and acted as pro-oxidants that promoted lipid oxidation in both high and low oxygen conditions. PMID:25977064

  10. Effect of substrate availability on nitrous oxide production by deammonification processes under anoxic conditions

    PubMed Central

    Schneider, Yvonne; Beier, Maike; Rosenwinkel, Karl‐Heinz

    2012-01-01

    Summary Due to its high global warming potential, nitrous oxide (N2O) emissions from wastewater treatment processes have recently received a high degree of attention. Nevertheless, there is still a lack of information regarding the microbiological processes leading to N2O production. In this study, two lab‐scale sequencing batch reactors were operated with deammonification biomass to investigate the role of denitrification and the influence of substrate availability regarding N2O formation during the anoxic phase of deammonification. Three different operational phases were established: within the first phase conversion by anammox was favoured and after a transition phase, denitrification activity was promoted. Low nitrous oxide production was observed during stable operation aiming for anammox conversion. Pulsed inflow of the wastewater containing ammonium (NH4+) and nitrite (NO2‐) led to increased N2O production rates. Within the period of denitrification as dominating nitrogen conversion process, the nitrous oxide concentration level was higher during continuous inflow conditions, but the reaction to pulsed inflow was less pronounced. The results indicated that denitrification was responsible for N2O formation from the deammonification biomass. Operational settings to achieve suppression of denitrification processes to a large extend were deducted from the results of the experiments. PMID:22296600

  11. Effect of substrate availability on nitrous oxide production by deammonification processes under anoxic conditions.

    PubMed

    Schneider, Yvonne; Beier, Maike; Rosenwinkel, Karl-Heinz

    2012-05-01

    Due to its high global warming potential, nitrous oxide (N(2)O) emissions from wastewater treatment processes have recently received a high degree of attention. Nevertheless, there is still a lack of information regarding the microbiological processes leading to N(2)O production. In this study, two lab-scale sequencing batch reactors were operated with deammonification biomass to investigate the role of denitrification and the influence of substrate availability regarding N(2)O formation during the anoxic phase of deammonification. Three different operational phases were established: within the first phase conversion by anammox was favoured and after a transition phase, denitrification activity was promoted. Low nitrous oxide production was observed during stable operation aiming for anammox conversion. Pulsed inflow of the wastewater containing ammonium (NH(4)(+)) and nitrite (NO(2)(-)) led to increased N(2)O production rates. Within the period of denitrification as dominating nitrogen conversion process, the nitrous oxide concentration level was higher during continuous inflow conditions, but the reaction to pulsed inflow was less pronounced. The results indicated that denitrification was responsible for N(2)O formation from the deammonification biomass. Operational settings to achieve suppression of denitrification processes to a large extend were deducted from the results of the experiments. PMID:22296600

  12. Dewatering of saline sewage sludge using iron-oxidizing bacteria: Effect of substrate concentration.

    PubMed

    Wong, Jonathan W C; Murugesan, Kumarasamy; Selvam, Ammaiyappan; Ravindran, Balasubramanian; Kurade, Mayur B; Yu, Shuk-Man

    2016-08-01

    This study investigated the improvement in dewaterability of activated sludge (ACS) and anaerobically digested sludge (ADS) through bioacidification approach using iron-oxidizing bacterium, Acidithiobacillus ferrooxidans. ACS and ADS were treated with A. ferrooxidans culture with addition of different concentrations of energy substrate, in terms of Fe(2+):sludge solids ratio (0:1, 0.01:1, 0.05:1 and 0.1:1), and the dewaterability was assessed by determining the capillary suction time (CST), time to filter (TTF) and specific resistance to filtration (SRF) of the sludge. The results revealed that the levels of Fe(2+) significantly influenced the sludge acidification (pH⩽3). The CST, TTF and SRF values rapidly decreased in treated sludge, indicating that dewaterability of the sludge was significantly (p<0.05) improved than untreated sludge. This investigation clearly demonstrates that A. ferrooxidans culture, as biogenic flocculant, can be potentially used for improving the sludge flocculation, stabilization and dewaterability. PMID:27095409

  13. Oxidative potential of some endophytic fungi using 1-indanone as a substrate.

    PubMed

    Fill, Taicia Pacheco; da Silva, Jose Vinicius; de Oliveira, Kleber Thiago; da Silva, Bianca Ferreira; Rodrigues-Fo, Edson

    2012-06-01

    The oxidative potential of the fungus Penicillium brasilianum, a strain isolated as an endophyte from a Meliaceae plant (Melia azedarach), was investigated using 1-indanone as a substrate to track the production of monooxygenases. The fungus produced the dihydrocoumarin from 1-indanone with the classical Baeyer-Villiger reaction regiochemistry, and (-)-(R)-3-hydroxy-1-indanone with 78% ee. Minor compounds resulting from lipase and SAM activities were also detected. The biotransformation procedures were also applied to a collection of Penicillium and Aspergillus fungi obtained from M. azedarach and Murraya paniculata. The results showed that Baeyer-Villiger were mostly active in fungi isolated from M. azedarach. Almost all of the fungi tested produced 3-hydroxy-1-indanone.. PMID:22573162

  14. Green luminescent center in undoped zinc oxide films deposited on silicon substrates

    NASA Astrophysics Data System (ADS)

    Lin, Bixia; Fu, Zhuxi; Jia, Yunbo

    2001-08-01

    The photoluminescence (PL) spectra of the undoped ZnO films deposited on Si substrates by dc reactive sputtering have been studied. There are two emission peaks, centered at 3.18 eV (UV) and 2.38 eV (green). The variation of these peak intensities and that of the I-V properties of the ZnO/Si heterojunctions were investigated at different annealing temperatures and atmospheres. The defect levels in ZnO films were also calculated using the method of full-potential linear muffin-tin orbital. It is concluded that the green emission corresponds to the local level composed by oxide antisite defect OZn rather than oxygen vacancy VO, zinc vacancy VZn, interstitial zinc Zni, and interstitial oxygen Oi.

  15. Purely sonochemical route for oriented zinc oxide nanowire growth on arbitrary substrate

    NASA Astrophysics Data System (ADS)

    Nayak, Avinash P.; Katzenmeyer, Aaron M.; Kim, Ja-Yeon; Kwon, Min Ki; Gosho, Yasuhiro; Islam, M. Saif

    2010-04-01

    We report a simple sonochemical method for the seeding and synthesis of Zinc Oxide nanowire arrays that can be formed on a number of substrates that are stable in alcohol and aqueous solution. Vertically aligned ZnO NWs were synthesized from a single solution at room-ambient via ultrasonic excitation. Prior to the NW growth, a ZnO seed layer was deposited using the same system with a different solution. The optimal conditions to produce a high density of oriented wires along with their optical characteristics are presented for ZnO NWs with a significantly high growth rate compared with traditional growth techniques such as evaporation, chemical vapor deposition and sputtering. Our method promises a mass-manufacturable process for fast and inexpensive ZnO NW production for practical low cost electronics, photonics and energy conversion applications.

  16. Laser scribing of indium tin oxide (ITO) thin films deposited on various substrates for touch panels

    NASA Astrophysics Data System (ADS)

    Tseng, Shih-Feng; Hsiao, Wen-Tse; Huang, Kuo-Cheng; Chiang, Donyau; Chen, Ming-Fei; Chou, Chang-Pin

    2010-12-01

    In this study, a Nd:YAG laser with wavelength of 1064 nm is used to scribe the indium tin oxide (ITO) thin films coated on three types of substrate materials, i.e. soda-lime glass, polycarbonate (PC), and cyclic-olefin-copolymer (COC) materials with thickness of 20 nm, 30 nm, and 20 nm, respectively. The effect of exposure time adjusted from 10 μs to 100 μs on the ablated mark width, depth, and electrical properties of the scribed film was investigated. The maximum laser power of 2.2 W was used to scribe these thin films. In addition, the surface morphology, surface reaction, surface roughness, optical properties, and electrical conductivity properties were measured by a scanning electron microscope, a three-dimensional confocal laser scanning microscope, an atomic force microscope, and a four-point probe. The measured results of surface morphology show that the residual ITO layer was produced on the scribed path with the laser exposure time at 10 μs and 20 μs. The better edge qualities of the scribed lines can be obtained when the exposure time extends from 30 μs to 60 μs. When the laser exposure time is longer than 60 μs, the partially burned areas of the scribed thin films on PC and COC substrates are observed. Moreover, the isolated line width and resistivity values increase when the laser exposure time increases.

  17. THz behavior of indium-tin-oxide films on p-Si substrates

    SciTech Connect

    Brown, E. R. Zhang, W-D.; Chen, H.; Mearini, G. T.

    2015-08-31

    This paper reports broadband THz free-space transmission measurements and modeling of indium-tin-oxide (ITO) thin films on p-doped Si substrates. Two such samples having ITO thickness of 50 and 100 nm, and DC sheet conductance 260 and 56 Ω/sq, respectively, were characterized between 0.2 and 1.2 THz using a frequency-domain spectrometer. The 50-nm-film sample displayed very flat transmittance over the 1-THz bandwidth, suggesting it is close to the critical THz sheet conductance that suppresses multi-pass interference in the substrate. An accurate transmission-line-based equivalent circuit is developed to explain the effect, and then used to show that the net reflectivity and absorptivity necessarily oscillate with frequency. This has important implications for the use of thin-film metallic coupling layers on THz components and devices, such as detectors and sources. Consistent with previous reported results, the sheet conductance that best fits the THz transmittance data is roughly 50% higher than the DC values for both samples.

  18. Flexible electrochromics: magnetron sputtered tungsten oxide (WO3-x) thin films on Lexan (optically transparent polycarbonate) substrates

    NASA Astrophysics Data System (ADS)

    Uday Kumar, K.; Murali, Dhanya S.; Subrahmanyam, A.

    2015-06-01

    Tungsten oxide (WO3-x) based electrochromics on flexible substrates is a topic of recent interest. The present communication reports the electrochromic properties of WO3-x thin films grown on lexan, an optically transparent polycarbonate thermoplastic substrate. The WO3-x films are prepared at room temperature (300 K) by the reactive DC magnetron sputtering technique. The physical properties of metal oxide thin films are known to be controlled by the oxygen stoichiometry of the film. In the present work, the WO3-x thin films are prepared by varying the oxygen flow rates. All the WO3-x thin films are amorphous in nature. The electrochromic performance of the WO3-x thin films is evaluated by cyclic voltammetry measurements on tin doped indium oxide (ITO) coated lexan and glass substrates. The optical band gap of WO3-x thin films grown on lexan substrates (at any given oxygen flow rate) is significantly higher than those grown on glass substrates. The coloration efficiency of WO3-x thin films (at an oxygen flow rate of 10 sccm) on lexan substrates is: 143.9 cm2 C-1 which is higher compared to that grown on glass: 90.4 cm2 C-1.

  19. Electronic interface properties of silicon substrates after ozone based wet-chemical oxidation studied by SPV measurements

    NASA Astrophysics Data System (ADS)

    Angermann, Heike; Wolke, Klaus; Gottschalk, Christiane; Moldovan, Ana; Roczen, Maurizio; Fittkau, Jens; Zimmer, Martin; Rentsch, Jochen

    2012-08-01

    The preparation of ultra-thin oxide layers on mono-crystalline silicon substrate surfaces with ozone dissolved in ultra pure water at ambient temperature was investigated as a low cost alternative to current wet-chemical cleaning and passivation processes in solar cell manufacturing. Surface photovoltage technique was applied as fast, nondestructive, and surface sensitive method, to provide detailed information about the influence of oxidation rate and substrate surface morphology on electronic properties of the oxidised silicon interfaces and subsequently prepared hydrogen terminated surfaces. Sequences of wet-chemical oxidation in ozone containing ultra pure water and subsequent oxide removal in diluted hydrofluoric acid solution could be utilised to prepare hydrophobic substrates, which are predominantly required as starting point for layer deposition and contact formation. On so prepared hydrogen-terminated substrates values of interface state densities Dit,min ≈ 5 × 1011 eV-1 cm-2 could be achieved, comparable to values obtained on the same substrates by the standard RCA process followed by HF dip.

  20. Measurement of β-oxidation capacity of biological samples by respirometry: a review of principles and substrates.

    PubMed

    Ojuka, Edward; Andrew, Brittany; Bezuidenhout, Nicole; George, Siddiqah; Maarman, Gerald; Madlala, Hlengiwe P; Mendham, Amy; Osiki, Prisca Ofure

    2016-05-01

    Oxidation of fatty acids is a major source of energy in the heart, liver, and skeletal muscle. It can be measured accurately using respirometry in isolated mitochondria, intact cells, and permeabilized cells or tissues. This technique directly measures the rate of oxygen consumption or flux at various respiratory states when appropriate substrates, uncouplers, and inhibitors are used. Acylcarnitines such as palmitoylcarnitine or octanoylcarnitine are the commonly used substrates. The β-oxidation pathway is prone to feedforward inhibition resulting from accumulation of short-chain acyl-CoA and depletion of CoA, but inclusion of malate or carnitine prevents accumulation of these intermediaries and CoA depletion. PMID:26908505

  1. Low-cost flexible supercapacitors based on laser reduced graphene oxide supported on polyethylene terephthalate substrate

    NASA Astrophysics Data System (ADS)

    Ghoniem, Engy; Mori, Shinsuke; Abdel-Moniem, Ahmed

    2016-08-01

    A controlled high powered CO2 laser system is used to reduce and pattern graphene oxide (GO) film supported onto a flexible polyethylene terephthalate (PET) substrate. The laser reduced graphene oxide (rGO) film is characterized and evaluated electrochemically in the absence and presence of an overlying anodicaly deposited thin film of pseuodcapactive MnO2 as electrodes for supercapacitor applications using aqueous electrolyte. The laser treatment of the GO film leads to an overlapped structure of defective multi-layer rGO sheets with an electrical conductivity of 273 S m-1. The rGO and MnO2/rGO electrodes exhibit specific capacitance in the range of 82-107 and 172-368 Fg-1 at applied current range of 0.1-1.0 mA cm-2 and retain 98 and 95% of their initial capacitances after 2000 cycles at a current density of 1.0 mA cm-2, respectively. Also, the rGO is assigned as an electrode material for flexible conventionally stacked and interdigitated in-plane supercapacitor structures using gel electrolyte. Three electrode architectures of 2, 4, and 6 sub-electrodes are studied for the interdigital in-plane design. The device with interdigital 6 sub-electrodes architecture I-PS(6) delivers power density of 537.1 Wcm-3 and an energy density of 0.45 mWh cm-3.

  2. Thermal stability studies of plasma sprayed yttrium oxide coatings deposited on pure tantalum substrate

    NASA Astrophysics Data System (ADS)

    Nagaraj, A.; Anupama, P.; Mukherjee, Jaya; Sreekumar, K. P.; Satpute, R. U.; Padmanabhan, P. V. A.; Gantayet, L. M.

    2010-02-01

    Plasma sprayed Yttrium oxide is used for coating of crucibles and moulds that are used at high temperature to handle highly reactive molten metals like uranium, titanium, chromium, and beryllium. The alloy bond layer is severely attacked by the molten metal. This commonly used layer contributes to the impurity addition to the pure liquid metal. Yttrium oxide was deposited on tantalum substrates (25 mm × 10mm × 1mm thk and 40 mm × 8mm × 1mm thk) by atmospheric plasma spray technique with out any bond coat using optimized coating parameters. Resistance to thermal shock was evaluated by subjecting the coated specimens, to controlled heating and cooling cycles between 300K to 1600K in an induction furnace in argon atmosphere having <= 0.1ppm of oxygen. The experiments were designed to examine the sample tokens by both destructive and non-destructive techniques, after a predetermined number of thermal cycles. The results upto 24 thermal cycles of 25 mm × 10mm × 1mm thk coupons and upto 6 cycles of 40 mm × 8mm × 1mm thk coupons are discussed. The coatings produced with the optimized parameters were found to exhibit excellent thermal shock resistance.

  3. [Oxidation of sulfur-containing substrates by an association of acidophilic chemolithotrophic microorganisms].

    PubMed

    Revenko, A A; Melamud, V S; Krasil'nikov, G S; Pivovarova, T A; Belyĭ, V A; Kondrat'eva, T F

    2009-01-01

    Quantitative and qualitative changes in the content of elements in the solid and liquid phases occurred as the pulp moved through fermenters during biooxidation of an ore flotation concentrate. The association of microorganisms were adapted for utilizing sulfur-containing substrates; however, the rate of their oxidation was insufficient, which led to an increase in the amount of sodium cyanide required for gold recovery. The replacement of one-fourth of the liquid phase of the pulp (density, 13%) with a mineral medium without an energy source, the fractional addition of FeSO4 x 7H2O (1 g/l per day), and the improvement of pulp aeration made it possible to increase the content of SO4(2-) by 80.7, 86.2, and 58.5%, respectively. When one-fourth of the liquid phasa of the pulp (density, 24%) was replaced with a mineral medium without an energy source, the rate of additional oxidation of sulfide minerals increased, which increased the efficiency of gold extraction into solution and gold recovery on charcoal by 3.4 and 3.6%, respectively, and reduced sodium cyanide consumption by 3 kg/ton. PMID:19764615

  4. Cyclic Oxidation Behavior of Cold Sprayed CuCrAl-Coated and Uncoated GRCop-84 Substrates for Space Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Raj, S. V.; Barrett, C.; Karthikeyan, J.; Garlick, R.

    2006-01-01

    A newly developed Cu-23 (wt %) Cr-5%Al (CuCrAl) alloy shown to resist hydridation and oxidation in an as-cast form is currently being considered as a protective coating for GRCop-84, which is an advanced copper alloy containing 8 (at.%) Cr and 4 (at.%) Nb. The coating was deposited on GRCop-84 substrates by the cold spray deposition technique. Cyclic oxidation tests conducted in air on both coated and uncoated substrates between 773 and 1073 K revealed that the coating remained intact and protected the substrate up to 1073 K. No significant weight loss of the coated specimens were observed at 773 and 873 K even after a cumulative cyclic time of 500 h. About a 10 percent weight loss observed at 973 and 1073 K was attributed to the excessive oxidation of the uncoated sides. In contrast, the uncoated substrate lost as much as 80 percent of its original weight under similar test conditions. It is concluded that the cold sprayed CuCrAl coating is suitable for protecting GRCop-84 substrates.

  5. Film-edge-induced dislocation generation in silicon substrates. II. Application of the theoretical model for local oxidation processes on (001) silicon substrates

    NASA Astrophysics Data System (ADS)

    Vanhellemont, J.; Amelinckx, S.; Claeys, C.

    1987-03-01

    A theoretical model which allows prediction of the type and of the equilibrium configuration of dislocations generated or captured in fcc substrates at the edges of thin films is applied to local oxidation processes on (001) Czochralski silicon substrates. Nitride film structures aligned along the two most interesting crystallographic directions on the (001) surface, i.e., the <110> and the <100> directions, are studied by high-voltage electron microscopy. The model allows to explain the observed dislocation types including most of the previous reports in the literature. Some numerical examples are given which illustrate the strength of the model to obtain even quantitative information both on the film stresses and on the critical glide force from the observed equilibrium configuration of the defects. Good agreement is obtained between the observed shape and position of the defects and computer simulations based on the model.

  6. Electrodeposited Manganese Oxides on Three-Dimensional Carbon Nanotube Substrate: Supercapacitive Behaviour in Aqueous and Organic Electrolytes

    SciTech Connect

    Nam,K.W.; Yang,X.

    2009-03-01

    Thin amorphous manganese oxide layers with a thickness of 3-5nm are electrodeposited on a carbon nanotube (CNT) film substrate that has a three-dimensional nanoporous structure (denoted asMnO2/CNT electrode). For the purpose of comparison, manganese oxide films are also electrodeposited on a flat Pt-coated Si wafer substrate (denoted as MnO2 film electrode). The pseudocapacitive properties of the MnO2 film and MnO2/CNT electrodes are examined in both aqueous electrolyte (1.0M KCl) and nonaqueousorganic electrolyte (1.0M LiClO4 in propylene carbonate). While both types of electrode showpseudocapacitive behaviour in the aqueous electrolyte, only the MnO2/CNT electrode does so in the organic electrolyte, due to its high oxide/electrolyte interfacial area and improved electron conduction through the CNT substrate. Compared with the MnO2 film electrode, the MnO2/CNT electrode shows a much higher specific capacitance and better high-rate capability, regardless of the electrolyte used.Use of the organic electrolyte results in a ∼6 times higher specific energy compared with that obtained with the aqueous electrolyte, while maintaining a similar specific power. The construction of a threedimensional nanoporous network structure consisting of a thin oxide layer on a CNT film substrate at the nm scale and the use of an organic electrolyte are promising approaches to improving the specific energyof supercapacitors.

  7. Heterologous Expression of Pleurotus eryngii Peroxidase Confirms Its Ability To Oxidize Mn2+ and Different Aromatic Substrates

    PubMed Central

    Ruiz-Dueñas, Francisco Javier; Martínez, María Jesús; Martínez, Ángel T.

    1999-01-01

    A versatile ligninolytic peroxidase has been cloned from Pleurotus eryngii and its allelic variant MnPL2 expressed in Aspergillus nidulans, with properties similar to those of the mature enzyme from P. eryngii. These include the ability to oxidize Mn2+ and aromatic substrates, confirming that this is a new peroxidase type sharing catalytic properties of lignin peroxidase and manganese peroxidase. PMID:10508113

  8. Method of depositing an electrically conductive oxide buffer layer on a textured substrate and articles formed therefrom

    DOEpatents

    Paranthaman, M. Parans; Aytug, Tolga; Christen, David K.

    2003-09-09

    An article with an improved buffer layer architecture includes a substrate having a textured metal surface, and an electrically conductive lanthanum metal oxide epitaxial buffer layer on the surface of the substrate. The article can also include an epitaxial superconducting layer deposited on the epitaxial buffer layer. An epitaxial capping layer can be placed between the epitaxial buffer layer and the superconducting layer. A method for preparing an epitaxial article includes providing a substrate with a metal surface and depositing on the metal surface a lanthanum metal oxide epitaxial buffer layer. The method can further include depositing a superconducting layer on the epitaxial buffer layer, and depositing an epitaxial capping layer between the epitaxial buffer layer and the superconducting layer.

  9. Method of depositing an electrically conductive oxide buffer layer on a textured substrate and articles formed therefrom

    DOEpatents

    Paranthaman, M. Parans; Aytug, Tolga; Christen, David K.

    2005-10-18

    An article with an improved buffer layer architecture includes a substrate having a textured metal surface, and an electrically conductive lanthanum metal oxide epitaxial buffer layer on the surface of the substrate. The article can also include an epitaxial superconducting layer deposited on the epitaxial buffer layer. An epitaxial capping layer can be placed between the epitaxial buffer layer and the superconducting layer. A method for preparing an epitaxial article includes providing a substrate with a metal surface and depositing on the metal surface a lanthanum metal oxide epitaxial buffer layer. The method can further include depositing a superconducting layer on the epitaxial buffer layer, and depositing an epitaxial capping layer between the epitaxial buffer layer and the superconducting layer.

  10. Localized Plasmon-Stimulated Nanochemistry of Graphene Oxide on a SERS Substrate.

    PubMed

    Ramanauskaite, Lina; Xu, Huizhong; Snitka, Valentinas

    2016-03-16

    In recent years, there has been remarkable progress in the reduction and functionalization of graphene oxide (GO) using nanoparticles and high-energy optical photons. Most of these reactions are carried out in solutions, whereas the local modification of GO on solid substrates still remains a challenge. In this work, we demonstrate the local reduction of GO and its further destruction, leading to the synthesis of polyaromatic hydrocarbons (PAHs) stimulated by localized surface plasmons (LSPs). The reduction of GO and the synthesis of PAHs have been carried out on a substrate designed for surface-enhanced Raman spectroscopy (SERS). We found that LSPs initiate the destruction of water molecules entrapped in the nanogaps between silver nanoparticles after the deposition of GO from the aqueous suspension. It was demonstrated that OH radicals, as a result of water decomposition, initiate the reduction of GO, leading to the synthesis of PAHs. The reactions have been observed in real time by using SERS. The measurement of current-voltage (I-V) characteristics through conductive atomic force microscopy (AFM), recorded in an LSP-stimulated area, have shown the increased electrical conductivity (more than ten times) compared with the conductivity of GO. The synthesis of new compounds in the LSP-stimulated area has been confirmed by the appearance of new peaks in the Raman spectra and nonlinear I-V characteristics typical for PAHs. We show that the used method allows the local modification of electrical properties of GO and controlled nanopattering of organic compounds on the surface. PMID:26728625

  11. Fabrication of silver nanoparticles decorated anodic aluminum oxide as the SERS substrate for the detection of pesticide thiram

    NASA Astrophysics Data System (ADS)

    Tan, En-zhong

    2015-07-01

    An efficient surface-enhanced Raman scattering (SERS) substrate is developed based on silver nanoparticles decorated anodic aluminum oxide (Ag/AAO). The AAO templates were fabricated using a two-step anodization approach, and silver nanoparticles (AgNPs) were obtained by thermal decomposition of Ag nitrate in AAO. The structure of Ag/AAO hybrid substrate is characterized by scanning electron microscopy (SEM). The results show that the as-prepared SERS substrates consist of high-density AgNPs with sizes of tens of nanometers. The AgNPs are adsorbed on the surface of AAO template in the form of network structure which is called "hot spot". The SERS enhancement ability of the nanostructure is verified using thiram as probing molecules. The limit of detection is as low as 1×10-9 mol/L. The results indicate that the as-prepared substrate possesses excellent SERS sensitivity, high stability and uniformity enhancement.

  12. Mechanical and piezoelectric properties of zinc oxide nanorods grown on conductive textile fabric as an alternative substrate

    NASA Astrophysics Data System (ADS)

    Khan, Azam; Hussain, Mushtaque; Nur, Omer; Willander, Magnus

    2014-08-01

    The present research is devoted to understanding the mechanism and causes of variation in the piezoelectric potential generated from vertically aligned zinc oxide (ZnO) nanorods (NRs), which were grown on a conductive textile fabric as an alternative substrate by using the aqueous chemical growth method. The piezoelectric voltage was harvested from vertically aligned ZnO NRs having different physical parameters by using atomic force microscopy in contact mode and the variation in the generated piezoelectricity was investigated. The generated output potential indicates that different physical parameters such aspect ratio, crystal size and lattice internal crystal strain have a strong influence on the piezoelectric properties of vertically aligned ZnO NRs, which were grown on a textile fabric. Presented results indicate that textiles can be used as an alternative substrate just like the other conventional substrates, because our results are similar/better than many reported works on conventional substrates.

  13. Method of depositing an electrically conductive oxide film on a textured metallic substrate and articles formed therefrom

    DOEpatents

    Christen, David K.; He, Qing

    2001-01-01

    The present invention provides a biaxially textured laminate article having a polycrystalline biaxially textured metallic substrate with an electrically conductive oxide layer epitaxially deposited thereon and methods for producing same. In one embodiment a biaxially texture Ni substrate has a layer of LaNiO.sub.3 deposited thereon. An initial layer of electrically conductive oxide buffer is epitaxially deposited using a sputtering technique using a sputtering gas which is an inert or forming gas. A subsequent layer of an electrically conductive oxide layer is then epitaxially deposited onto the initial layer using a sputtering gas comprising oxygen. The present invention will enable the formation of biaxially textured devices which include HTS wires and interconnects, large area or long length ferromagnetic and/or ferroelectric memory devices, large area or long length, flexible light emitting semiconductors, ferroelectric tapes, and electrodes.

  14. Method of depositing an electrically conductive oxide film on a textured metallic substrate and articles formed therefrom

    DOEpatents

    Christen, David K.; He, Qing

    2003-04-29

    The present invention provides a biaxially textured laminate article having a polycrystalline biaxially textured metallic substrate with an electrically conductive oxide layer epitaxially deposited thereon and methods for producing same. In one embodiment a biaxially texture Ni substrate has a layer of LaNiO.sub.3 deposited thereon. An initial layer of electrically conductive oxide buffer is epitaxially deposited using a sputtering technique using a sputtering gas which is an inert or forming gas. A subsequent layer of an electrically conductive oxide layer is then epitaxially deposited onto the initial layer using a sputtering gas comprising oxygen. The present invention will enable the formation of biaxially textured devices which include HTS wires and interconnects, large area or long length ferromagnetic and/or ferroelectric memory devices, large area or long length, flexible light emitting semiconductors, ferroelectric tapes, and electrodes.

  15. Stereoselectivity in the oxidation of bufuralol, a chiral substrate, by human cytochrome P450s.

    PubMed

    Narimatsu, Shizuo; Takemi, Chie; Kuramoto, Shino; Tsuzuki, Daisuke; Hichiya, Hiroyuki; Tamagake, Keietsu; Yamamoto, Shigeo

    2003-05-01

    Bufuralol (BF), a nonselective beta-adrenoceptor blocking agent, has a chiral center in its molecule, yielding the enantiomers 1'R-BF and 1'S-BF. beta-Adrenoceptor blocking potency is much higher in 1'S-BF than in 1'R-BF. One of the metabolic pathways of BF is 1"-hydroxylation of an ethyl group attached at the aromatic 7-position forming a carbinol metabolite (1"-hydroxybufuralol, 1"-OH-BF), and further oxidation (or dehydrogenation) produces a ketone metabolite (1-oxobufuralol, 1"-Oxo-BF). Both 1"-OH-BF and 1"-Oxo-BF are known to have beta-adrenoceptor blocking activities comparable to or higher than those of the parent drug. The 1"-hydroxylation introduces another chiral center into the BF molecule and four 1"-OH-BF diastereomers are formed from BF racemate in mammals, including humans, making elucidation of the metabolic profiles complicated. HPLC methods employing derivatization, reversed phase, or chiral columns have been developed to efficiently separate the four 1"-OH-BF diastereomers formed from BF enantiomers or racemate. Accumulated in vitro experimental results revealed that 1'R-BF is a much more preferential substrate than 1'S-BR for BF 1"-hydroxylation in human liver microsomes. Kinetic studies using recombinant human cytochrome P450 (CYP) enzymes indicate that CYP2D6 serves as a major BF 1"-hydroxylase and that CYP1A2 and CYP2C19 also contribute to BF 1"-hydroxylation in human livers. This mini-review summarizes the knowledge reported so far on the pharmacology of BF and its metabolites and the profiles of BF metabolism, especially focusing on the stereoselectivity in the oxidation of BF mainly in human livers and recombinant CYP enzymes. PMID:12666241

  16. Rate-determining Attack on Substrate Precedes Rieske Cluster Oxidation during cis-Dihydroxylation by Benzoate Dioxygenase

    PubMed Central

    Rivard, Brent S.; Rogers, Melanie S.; Marell, Daniel J.; Neibergall, Matthew B.; Chakrabarty, Sarmistha; Cramer, Christopher J.; Lipscomb, John D.

    2015-01-01

    Rieske dearomatizing dioxygenases utilize a Rieske iron-sulfur cluster and a mononuclear Fe(II) located 15 Å across a subunit boundary to catalyze O2-dependent formation of cis-dihydrodiol products from aromatic substrates. During catalysis, O2 binds to the Fe(II) while the substrate bind nearby. Single turnover reactions have shown that one electron from each metal center is required for catalysis. This finding suggested that the reactive intermediate is Fe(III)-(H)peroxo or HO-Fe(V)=O formed by O-O bond scission. Surprisingly, several kinetic phases were observed during the single turnover Rieske cluster oxidation. Here, the Rieske cluster oxidation and product formation steps of a single turnover of benzoate 1,2-dioxygenase are investigated using benzoate and three fluorinated analogs. It is shown that the rate constant for product formation correlates with the reciprocal relaxation time of only the fastest kinetic phase (RRT-1) for each substrate, suggesting that the slower phases are not mechanistically relevant. RRT-1 is strongly dependent on substrate type, suggesting a role for substrate in electron transfer from the Rieske cluster to the mononuclear iron site. This insight, together with the substrate and O2 concentration dependencies of RRT-1, indicates that a reactive species is formed after substrate and O2 binding, but before electron transfer from the Rieske cluster. Computational studies show that RRT-1 is correlated with the electron density at the substrate carbon closest to the Fe(II), consistent with initial electrophilic attack by an Fe(III)-superoxo intermediate. The resulting Fe(III)-peroxo-aryl radical species would then readily accept an electron from the Rieske cluster to complete the cis-dihydroxylation reaction. PMID:26154836

  17. Laser Cladding to Improve Oxidation Behavior of Air Plasma-Sprayed Ni-20Cr Coating on Stainless Steel Substrate

    NASA Astrophysics Data System (ADS)

    Rauf, M. Mudassar; Shahid, Muhammad; Nusair Khan, A.; Mehmood, K.

    2015-09-01

    Air plasma-sprayed Ni-20Cr coating on stainless steel (AISI-304) substrate was re-melted using CO2 laser to remove the inherent defects, i.e., porosity, splat boundaries, and oxides of air plasma-sprayed coating. The (1) uncoated, (2) air plasma-sprayed, and (3) laser-re-melted specimens were exposed to cyclic oxidation at 900 °C for a hundred cycles run. The oxidation products were characterized using XRD and SEM. Weight changes were determined after every 4th cycle; Uncoated samples showed severe oxidation indicated by substantial weight loss, whereas air plasma-coated samples demonstrated noticeable weight gain. However, oxidation resistance of laser-cladded samples was found to be significantly improved as the samples showed negligible weight change; porosity within the coating was minimized with an improvement in interface quality causing reduction in delamination damage.

  18. Correlating the chemical composition and size of various metal oxide substrates with the catalytic activity and stability of as-deposited Pt nanoparticles for the methanol oxidation reaction

    SciTech Connect

    Megan E. Scofield; Wong, Stanislaus S.; Koenigsmann, Christopher; Bobb-Semple, Dara; Tao, Jing; Tong, Xiao; Wang, Lei; Lewis, Crystal S.; Vuklmirovic, Miomir; Zhu, Yimei; Adzic, Radoslav R.

    2015-12-09

    The performance of electrode materials in conventional direct alcohol fuel cells (DAFC) is constrained by (i) the low activity of the catalyst materials relative to their overall cost, (ii) the poisoning of the active sites due to the presence of partially oxidized carbon species (such as but not limited to CO, formate, and acetate) produced during small molecule oxidation, and (iii) the lack of catalytic stability and durability on the underlying commercial carbon support. Therefore, as a viable alternative, we have synthesized various metal oxide and perovskite materials of different sizes and chemical compositions as supports for Pt nanoparticles (NPs). Our results including unique mechanistic studies demonstrate that the SrRuO3 substrate with immobilized Pt NPs at its surface evinces the best methanol oxidation performance as compared with all of the other substrate materials tested herein, including commercial carbon itself. In addition, data from electron energy loss spectroscopy (EELS) and X-ray photoelectron spectroscopy (XPS) confirmed the presence of electron transfer from bound Pt NPs to surface Ru species within the SrRuO3 substrate itself, thereby suggesting that favorable metal support interactions are responsible for the increased methanol oxidation reaction (MOR) activity of Pt species with respect to the underlying SrRuO3 composite catalyst material.

  19. Correlating the chemical composition and size of various metal oxide substrates with the catalytic activity and stability of as-deposited Pt nanoparticles for the methanol oxidation reaction

    DOE PAGESBeta

    Megan E. Scofield; Wong, Stanislaus S.; Koenigsmann, Christopher; Bobb-Semple, Dara; Tao, Jing; Tong, Xiao; Wang, Lei; Lewis, Crystal S.; Vuklmirovic, Miomir; Zhu, Yimei; et al

    2015-12-09

    The performance of electrode materials in conventional direct alcohol fuel cells (DAFC) is constrained by (i) the low activity of the catalyst materials relative to their overall cost, (ii) the poisoning of the active sites due to the presence of partially oxidized carbon species (such as but not limited to CO, formate, and acetate) produced during small molecule oxidation, and (iii) the lack of catalytic stability and durability on the underlying commercial carbon support. Therefore, as a viable alternative, we have synthesized various metal oxide and perovskite materials of different sizes and chemical compositions as supports for Pt nanoparticles (NPs).more » Our results including unique mechanistic studies demonstrate that the SrRuO3 substrate with immobilized Pt NPs at its surface evinces the best methanol oxidation performance as compared with all of the other substrate materials tested herein, including commercial carbon itself. In addition, data from electron energy loss spectroscopy (EELS) and X-ray photoelectron spectroscopy (XPS) confirmed the presence of electron transfer from bound Pt NPs to surface Ru species within the SrRuO3 substrate itself, thereby suggesting that favorable metal support interactions are responsible for the increased methanol oxidation reaction (MOR) activity of Pt species with respect to the underlying SrRuO3 composite catalyst material.« less

  20. Xylo- and cello-oligosaccharide oxidation by gluco-oligosaccharide oxidase from Sarocladium strictum and variants with reduced substrate inhibition

    PubMed Central

    2013-01-01

    Background The oxidation of carbohydrates from lignocellulose can facilitate the synthesis of new biopolymers and biochemicals, and also reduce sugar metabolism by lignocellulolytic microorganisms, reserving aldonates for fermentation to biofuels. Although oxidoreductases that oxidize cellulosic hydrolysates have been well characterized, none have been reported to oxidize substituted or branched xylo-oligosaccharides. Moreover, this is the first report that identifies amino acid substitutions leading to GOOX variants with reduced substrate inhibition. Results The recombinant wild type gluco-oligosaccharide oxidase (GOOX) from the fungus Sarocladium strictum, along with variants that were generated by site-directed mutagenesis, retained the FAD cofactor, and showed high activity on cello-oligosaccharide and xylo-oligosaccharides, including substituted and branched xylo-oligosaccharides. Mass spectrometric analyses confirmed that GOOX introduces one oxygen atom to oxidized products, and 1H NMR and tandem mass spectrometry analysis confirmed that oxidation was restricted to the anomeric carbon. The A38V mutation, which is close to a predicted divalent ion-binding site in the FAD-binding domain of GOOX but 30 Å away from the active site, significantly increased the kcat and catalytic efficiency of the enzyme on all oligosaccharides. Eight amino acid substitutions were separately introduced to the substrate-binding domain of GOOX-VN (at positions Y72, E247, W351, Q353 and Q384). In all cases, the Km of the enzyme variant was higher than that of GOOX, supporting the role of corresponding residues in substrate binding. Most notably, W351A increased Km values by up to two orders of magnitude while also increasing kcat up to 3-fold on cello- and xylo-oligosaccharides and showing no substrate inhibition. Conclusions This study provides further evidence that S. strictum GOOX has broader substrate specificity than the enzyme name implies, and that substrate inhibition can be

  1. Compound semiconductor native oxide-based technologies for optical and electrical devices grown on gallium arsenide substrates using MOCVD

    NASA Astrophysics Data System (ADS)

    Holmes, Adrian Lawrence

    1999-11-01

    The beginning of the modern microelectronics industry can be traced back to an invention made in 1947 when Bardeen and Brattain created the first semiconductor switch, called a transistor. Several other important discoveries followed; however, two of the more significant were (i) the development of the first planar process using silicon dioxide (SiO2) as a mask for diffusions into silicon by Frosch in 1955, and (ii) the subsequent integration of several transistors in tiny circuits by Kilby in 1958. Due to the superior quality of the SiO2-silicon interface, Si-based metal-oxide-semiconductor (MOS) transistors have primarily been used in integrated circuits. Until recently, compound semiconductors did not have a native oxide of sufficient quality to create similar MOS transistors. In 1990, research performed by Professor Holonyak and his group at the University of Illinois at Urbana-Champaign has led to a high-quality, stable, and insulating native oxide created from aluminum-containing compound semiconductor alloys. This study investigates native oxide films that are formed by the thermal oxidation of AlAs and InAlP epitaxial layers grown lattice-matched on GaAs substrates using metalorganic chemical vapor deposition (MOCVD). The primary goal is to evaluate how these native oxides can help form novel device structures and transistors. To qualify the material properties of these native oxide films, we have used several characterization techniques including photoluminescence, cross-sectional scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Additionally, we have performed leakage current and capacitance-voltage measurements to evaluate the electrical characteristics of the native oxide-semiconductor interface. The kinetics of the thermal oxidation process for both the surface oxidation of InAlP and lateral oxidation of AlAs are studied and contrasted. Aided by this knowledge, we have created a sealed

  2. Optical and Structural Properties of Europium Oxide Thin Films on Silicon Substrates

    NASA Astrophysics Data System (ADS)

    Bellocchi, Gabriele; Franzò, G.; Iacona, F.; Boninelli, S.; Miritello, M.; Terrasi, A.; Spinella, C.; Priolo, F.

    Europium-based materials are known for their intense and stable emission in the visible region. Moreover Eu is stable in both its divalent and trivalent oxidation states. In particular, emission of Eu2+ is much stronger, being allowed for electric dipole transition rules and is characterized by a broad peak, centered in the wavelength range 400-600 nm, while that of Eu3+ presents several sharp lines at around 600 nm. These peculiar optical properties make Eu-based systems an interesting material for photonic applications. The optical and structural properties of Eu2O3 thin films grown by RF magnetron sputtering on Si substrates have been studied. PL emission has been observed at room temperature and it is strongly dependent on the thermal process. In particular, annealing in O2 atmosphere leads to an enhancement of the Eu3+ emission, while films annealed in N2 ambient exhibit a very intense PL signal due to Eu2+. The chemical and structural characterization of the films, performed by TEM and XPS, reveals that a massive mixing at the Eu2O3-Si interface occurs in N2-annealed samples, leading to the formation of Eu (II) silicates, while in the case of O2-annealed samples we observe the formation of a SiOx layer at the interface, that minimize the diffusion of Si into the Eu2O3 layer.

  3. Uncouplers of mitochondrial oxidative phosphorylation are not substrates of the erythrocyte glutathione-S-conjugate pump.

    PubMed

    Sokal, A; Bartosz, G

    1998-01-01

    Uncouplers of mitochondrial oxidative phosphorylation, dinitrophenol (DNP) and carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP), were found to stimulate Mg(2+)-ATPase activity of human erythrocyte membranes in a manner competitive with respect to 2,4-dinitrophenyl-S-glutathione (DNP-SG) which suggested that these compounds may also be substrates of the glutathione-S-conjugate pump. We confirm that the stimulation of erythrocyte membrane ATPase activity by DNP and by another uncoupler, carbonyl cyanide m-chlorophenylhydrazone (CCCP), is competitive with respect to DNP-SG. However, we found no evidence for active transport of DNP and CCCP out of erythrocytes and demonstrate that they inhibit the low-affinity component of DNP-SG transport noncompetitively while stimulating the high-affinity DNP-SG transport (mediated by multidrug resistance-associated protein, MRP1). Implications of these findings may indicate the electrogenic nature of MRP1-mediated transport of glutathione-S conjugates and stimulation of aminophospholipid translocase (flippase) rather than the glutathione-S-conjugate pump by the uncouplers. PMID:9439589

  4. Optoelectrochemical biorecognition by optically transparent highly conductive graphene-modified fluorine-doped tin oxide substrates.

    PubMed

    Lamberti, F; Brigo, L; Favaro, M; Luni, C; Zoso, A; Cattelan, M; Agnoli, S; Brusatin, G; Granozzi, G; Giomo, M; Elvassore, N

    2014-12-24

    Both optical and electrochemical graphene-based sensors have gone through rapid development, reaching high sensitivity at low cost and with fast response time. However, the complex validating biochemical operations, needed for their consistent use, currently limits their effective application. We propose an integration strategy for optoelectrochemical detection that overcomes previous limitations of these sensors used separately. We develop an optoelectrochemical sensor for aptamer-mediated protein detection based on few-layer graphene immobilization on selectively modified fluorine-doped tin oxide (FTO) substrates. Our results show that the electrochemical properties of graphene-modified FTO samples are suitable for complex biological detection due to the stability and inertness of the engineered electrodic interface. In addition, few-layer immobilization of graphene sheets through electrostatic linkage with an electrochemically grafted FTO surface allows obtaining an optically accessible and highly conductive platform. As a proof of concept, we used insulin as the target molecule to reveal in solution. Because of its transparency and low sampling volume (a few microliters), our sensing unit can be easily integrated in lab-on-a-chip cell culture systems for effectively monitoring subnanomolar concentrations of proteins relevant for biomedical applications. PMID:25438087

  5. Transparent resistive switching memory using aluminum oxide on a flexible substrate

    NASA Astrophysics Data System (ADS)

    Yeom, Seung-Won; Shin, Sang-Chul; Kim, Tan-Young; Ha, Hyeon Jun; Lee, Yun-Hi; Shim, Jae Won; Ju, Byeong-Kwon

    2016-02-01

    Resistive switching memory (ReRAM) has attracted much attention in recent times owing to its fast switching, simple structure, and non-volatility. Flexible and transparent electronic devices have also attracted considerable attention. We therefore fabricated an Al2O3-based ReRAM with transparent indium-zinc-oxide (IZO) electrodes on a flexible substrate. The device transmittance was found to be higher than 80% in the visible region (400-800 nm). Bended states (radius = 10 mm) of the device also did not affect the memory performance because of the flexibility of the two transparent IZO electrodes and the thin Al2O3 layer. The conduction mechanism of the resistive switching of our device was explained by ohmic conduction and a Poole-Frenkel emission model. The conduction mechanism was proved by oxygen vacancies in the Al2O3 layer, as analyzed by x-ray photoelectron spectroscopy analysis. These results encourage the application of ReRAM in flexible and transparent electronic devices.

  6. Transparent resistive switching memory using aluminum oxide on a flexible substrate.

    PubMed

    Yeom, Seung-Won; Shin, Sang-Chul; Kim, Tan-Young; Ha, Hyeon Jun; Lee, Yun-Hi; Shim, Jae Won; Ju, Byeong-Kwon

    2016-02-19

    Resistive switching memory (ReRAM) has attracted much attention in recent times owing to its fast switching, simple structure, and non-volatility. Flexible and transparent electronic devices have also attracted considerable attention. We therefore fabricated an Al2O3-based ReRAM with transparent indium-zinc-oxide (IZO) electrodes on a flexible substrate. The device transmittance was found to be higher than 80% in the visible region (400-800 nm). Bended states (radius = 10 mm) of the device also did not affect the memory performance because of the flexibility of the two transparent IZO electrodes and the thin Al2O3 layer. The conduction mechanism of the resistive switching of our device was explained by ohmic conduction and a Poole-Frenkel emission model. The conduction mechanism was proved by oxygen vacancies in the Al2O3 layer, as analyzed by x-ray photoelectron spectroscopy analysis. These results encourage the application of ReRAM in flexible and transparent electronic devices. PMID:26763473

  7. Substrate-dependent nitric oxide synthesis by secreted endoplasmic reticulum aminopeptidase 1 in macrophages.

    PubMed

    Goto, Yoshikuni; Ogawa, Kenji; Nakamura, Takahiro J; Hattori, Akira; Tsujimoto, Masafumi

    2015-06-01

    In this study, we examined the role of aminopeptidases with reference to endoplasmic reticulum aminopeptidase 1 (ERAP1) in nitric oxide (NO) synthesis employing murine macrophage cell line RAW264.7 cells activated by lipopolysaccharide (LPS) and interferon (IFN)-γ and LPS-activated peritoneal macrophages derived from ERAP1 knockout mouse. When NO synthesis was measured in the presence of peptides having N-terminal Arg, comparative NO synthesis was seen with that measured in the presence of Arg. In the presence of an aminopeptidase inhibitor amastatin, NO synthesis in activated RAW264.7 cells was significantly decreased. These results suggest that aminopeptidases are involved in the NO synthesis in activated RAW264.7 cells. Subsequently, significant reduction of NO synthesis was observed in ERAP1 knockdown cells compared with wild-type cells. This reduction was rescued by exogenously added ERAP1. Furthermore, when peritoneal macrophages prepared from ERAP1 knockout mouse were employed, reduction of NO synthesis in knockout mouse macrophages was also attributable to ERAP1. In the presence of amastatin, further reduction was observed in knockout mouse-derived macrophages. Taken together, these results suggest that several aminopeptidases play important roles in the maximum synthesis of NO in activated macrophages in a substrate peptide-dependent manner and ERAP1 is one of the aminopeptidases involved in the NO synthesis. PMID:25577645

  8. Oxidation and interdiffusion behavior of Niobium substrate coated MoSi2 coating prepared by spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Yan, JianHui; Wang, Yi; Liu, LongFei; Wang, Yueming

    2014-11-01

    In order to protect Niobium material from oxidation, MoSi2 coating was prepared on the Niobium substrate by spark plasma sintering. Oxidation behavior of MoSi2 coating was investigated in air over the temperature range of 1200-1500 °C. The interfacial diffusion between MoSi2 coating and Niobium substrate was also examined. Dense MoSi2 coating was successfully prepared using spark plasma sintering. The porosities of top and side coatings are about 5.5% and 6.4%, respectively. No cracks were present in the MoSi2 coating. Cracking and spallation of the SiO2 scale did not occur at test temperatures. Two intermediate phases-(Nb,Mo)5Si3 and Nb5Si3 phases, were detected in the boundary of MoSi2 coating and Nb substrate. The growth of the reaction layer was dominated by the diffusion of Si toward the Nb substrate and obeyed a parabolic rate law. A multi-layered structural coating formed on Nb substrate, which consisted of MoSi2, (Mo,Nb)5Si3 and Nb5Si3 in turn.

  9. Probing the structural dependency of photoinduced properties of colloidal quantum dots using metal-oxide photo-active substrates

    SciTech Connect

    Patty, Kira; Campbell, Quinn; Hamilton, Nathan; West, Robert G.; Sadeghi, Seyed M.; Mao, Chuanbin

    2014-09-21

    We used photoactive substrates consisting of about 1 nm coating of a metal oxide on glass substrates to investigate the impact of the structures of colloidal quantum dots on their photophysical and photochemical properties. We showed during irradiation these substrates can interact uniquely with such quantum dots, inducing distinct forms of photo-induced processes when they have different cores, shells, or ligands. In particular, our results showed that for certain types of core-shell quantum dot structures an ultrathin layer of a metal oxide can reduce suppression of quantum efficiency of the quantum dots happening when they undergo extensive photo-oxidation. This suggests the possibility of shrinking the sizes of quantum dots without significant enhancement of their non-radiative decay rates. We show that such quantum dots are not influenced significantly by Coulomb blockade or photoionization, while those without a shell can undergo a large amount of photo-induced fluorescence enhancement via such blockade when they are in touch with the metal oxide.

  10. Large-area alignment of tungsten oxide nanowires over flat and patterned substrates for room-temperature gas sensing.

    PubMed

    Cheng, Wei; Ju, Yanrui; Payamyar, Payam; Primc, Darinka; Rao, Jingyi; Willa, Christoph; Koziej, Dorota; Niederberger, Markus

    2015-01-01

    Alignment of nanowires over a large area of flat and patterned substrates is a prerequisite to use their collective properties in devices such as gas sensors. In this work, uniform single-crystalline ultrathin W18 O49 nanowires with diameters less than 2 nm and aspect ratios larger than 100 have been synthesized, and, despite their flexibility, assembled into thin films with high orientational order over a macroscopic area by the Langmuir-Blodgett technique. Alignment of the tungsten oxide nanowires was also possible on top of sensor substrates equipped with electrodes. Such sensor devices were found to exhibit outstanding sensitivity to H2 at room temperature. PMID:25412600

  11. Nd:YVO4 laser direct ablation of indium tin oxide films deposited on glass and polyethylene terephthalate substrates.

    PubMed

    Wang, Jian-Xun; Kwon, Sang Jik; Han, Jae-Hee; Cho, Eou Sik

    2013-09-01

    A Q-switched diode-pumped neodymium-doped yttrium vanadate (Nd:YVO4, lambda = 1064 nm) laser was applied to obtain the indium tin oxide (ITO) patterns on flexible polyethylene terephthalate (PET) substrate by a direct etching method. After the ITO films were deposited on a soda-lime glass and PET substrate, laser ablations were carried out on the ITO films for various conditions and the laser ablated results on the ITO films were investigated and analyzed considering the effects of substrates on the laser etching. The laser ablated widths on ITO deposited on glass were found to be much narrower than those on ITO deposited on PET substrate, especially, at a higher scanning speed of laser beam such as 1000 mm/s and 2000 mm/s. As the thermal conductivity of glass substrate is about 7.5 times higher than that of PET, more thermal energy would be spread and transferred to lateral direction in the ITO film in case of PET substrate. PMID:24205645

  12. Plasma surface oxidation of 316L stainless steel for improving adhesion strength of silicone rubber coating to metal substrate

    NASA Astrophysics Data System (ADS)

    Latifi, Afrooz; Imani, Mohammad; Khorasani, Mohammad Taghi; Daliri Joupari, Morteza

    2014-11-01

    Stainless steel 316L is one of the most widely used materials for fabricating of biomedical devices hence, improving its surface properties is still of great interest and challenging in biomaterial sciences. Plasma oxidation, in comparison to the conventional chemical or mechanical methods, is one of the most efficient methods recently used for surface treatment of biomaterials. Here, stainless steel specimens were surface oxidized by radio-frequency plasma irradiation operating at 34 MHz under pure oxygen atmosphere. Surface chemical composition of the samples was significantly changed after plasma oxidation by appearance of the chromium and iron oxides on the plasma-oxidized surface. A wettable surface, possessing high surface energy (83.19 mN m-1), was observed after plasma oxidation. Upon completion of the surface modification process, silicone rubber was spray coated on the plasma-treated stainless steel surface. Morphology of the silicone rubber coating was investigated by scanning electron microscopy (SEM). A uniform coating was formed on the oxidized surface with no delamination at polymer-metal interface. Pull-off tests showed the lowest adhesion strength of coating to substrate (0.12 MPa) for untreated specimens and the highest (0.89 MPa) for plasma-oxidized ones.

  13. Composite plasma electrolytic oxidation to improve the thermal radiation performance and corrosion resistance on an Al substrate

    NASA Astrophysics Data System (ADS)

    Kim, Donghyun; Sung, Dahye; Lee, Junghoon; Kim, Yonghwan; Chung, Wonsub

    2015-12-01

    A composite plasma electrolytic oxidation (PEO) was performed for enhancing the thermal radiation performance and corrosion resistance on an Al alloy by dispersing cupric oxide (CuO) particles in a conventional PEO electrolyte. Cu-based oxides (CuO and Cu2O) formed by composite PEO increased the emissivity of the substrate to 0.892, and made the surface being dark color, similar to a black body, i.e., an ideal radiator. In addition, the corrosion resistance was analyzed using potentio-dynamic polarization and electrochemical impedance spectroscopy tests in 3.5 wt.% NaCl aqueous solution. An optimum condition of 10 ampere per square decimeter (ASD) current density and 30 min processing time produced appropriate surface morphologies and coating thicknesses, as well as dense Cu- and Al-based oxides that constituted the coating layers.

  14. Growth of light-emitting SiGe heterostructures on strained silicon-on-insulator substrates with a thin oxide layer

    SciTech Connect

    Baidakova, N. A.; Bobrov, A. I.; Drozdov, M. N.; Novikov, A. V.; Pavlov, D. A.; Shaleev, M. V.; Yunin, P. A.; Yurasov, D. V.; Krasilnik, Z. F.

    2015-08-15

    The possibility of using substrates based on “strained silicon on insulator” structures with a thin (25 nm) buried oxide layer for the growth of light-emitting SiGe structures is studied. It is shown that, in contrast to “strained silicon on insulator” substrates with a thick (hundreds of nanometers) oxide layer, the temperature stability of substrates with a thin oxide is much lower. Methods for the chemical and thermal cleaning of the surface of such substrates, which make it possible to both retain the elastic stresses in the thin Si layer on the oxide and provide cleaning of the surface from contaminating impurities, are perfecte. It is demonstrated that it is possible to use the method of molecular-beam epitaxy to grow light-emitting SiGe structures of high crystalline quality on such substrates.

  15. Ex Vivo Antioxidant Activity of Selected Medicinal Plants against Fenton Reaction-Mediated Oxidation of Biological Lipid Substrates

    PubMed Central

    Pai Kotebagilu, Namratha; Reddy Palvai, Vanitha; Urooj, Asna

    2015-01-01

    Free radical-mediated oxidation is often linked to various degenerative diseases. Biological substrates with lipids as major components are susceptible to oxygen-derived lipid peroxidation due to their composition. Lipid peroxide products act as biomarkers in evaluating the antioxidant potential of various plants and functional foods. The study focused on evaluation of the antioxidant potential of two extracts (methanol and 80% methanol) of four medicinal plants, Andrographis paniculata, Costus speciosus, Canthium parviflorum, and Abrus precatorius, against Fenton reaction-mediated oxidation of three biological lipid substrates; cholesterol, low-density lipoprotein, and brain homogenate. The antioxidant activity of the extracts was measured by thiobarbituric acid reactive substances method. Also, the correlation between the polyphenol, flavonoid content, and the antioxidant activity in biological substrates was analyzed. Results indicated highest antioxidant potential by 80% methanol extract of Canthium parviflorum (97.55%), methanol extract of Andrographis paniculata (72.15%), and methanol extract of Canthium parviflorum (49.55%) in cholesterol, low-density lipoprotein, and brain, respectively. The polyphenol and flavonoid contents of methanol extract of Andrographis paniculata in cholesterol (r = 0.816) and low-density lipoprotein (r = 0.948) and Costus speciosus in brain (r = 0.977, polyphenols, and r = 0.949, flavonoids) correlated well with the antioxidant activity. The findings prove the antioxidant potential of the selected medicinal plants against Fenton reaction in biological lipid substrates. PMID:26933511

  16. Ex Vivo Antioxidant Activity of Selected Medicinal Plants against Fenton Reaction-Mediated Oxidation of Biological Lipid Substrates.

    PubMed

    Pai Kotebagilu, Namratha; Reddy Palvai, Vanitha; Urooj, Asna

    2015-01-01

    Free radical-mediated oxidation is often linked to various degenerative diseases. Biological substrates with lipids as major components are susceptible to oxygen-derived lipid peroxidation due to their composition. Lipid peroxide products act as biomarkers in evaluating the antioxidant potential of various plants and functional foods. The study focused on evaluation of the antioxidant potential of two extracts (methanol and 80% methanol) of four medicinal plants, Andrographis paniculata, Costus speciosus, Canthium parviflorum, and Abrus precatorius, against Fenton reaction-mediated oxidation of three biological lipid substrates; cholesterol, low-density lipoprotein, and brain homogenate. The antioxidant activity of the extracts was measured by thiobarbituric acid reactive substances method. Also, the correlation between the polyphenol, flavonoid content, and the antioxidant activity in biological substrates was analyzed. Results indicated highest antioxidant potential by 80% methanol extract of Canthium parviflorum (97.55%), methanol extract of Andrographis paniculata (72.15%), and methanol extract of Canthium parviflorum (49.55%) in cholesterol, low-density lipoprotein, and brain, respectively. The polyphenol and flavonoid contents of methanol extract of Andrographis paniculata in cholesterol (r = 0.816) and low-density lipoprotein (r = 0.948) and Costus speciosus in brain (r = 0.977, polyphenols, and r = 0.949, flavonoids) correlated well with the antioxidant activity. The findings prove the antioxidant potential of the selected medicinal plants against Fenton reaction in biological lipid substrates. PMID:26933511

  17. Oxidations of Organic and Inorganic Substrates by Superoxo-, hydroperoxo-, and oxo-compounds of the transition metals.

    SciTech Connect

    Michael John Vasbinder

    2006-12-12

    Hammett correlation. It was found that the values of the Hammett reaction constant PN were -1.0(1) for 4-nitro-2-methylpyridine-N-oxide and -2.6(4) for 4-methylpyridine-N-oxide as substrates. The negative value confirms pyridine is acting as a nucleophile. Nucleophiles other than pyridine derivatives were also tested. In the end, it was found that the most effective nucleophiles were the pyridine-N-oxides themselves, meaning that a second equivalent of substrate serves as the most efficient promoter of this oxygen-atom transfer reaction. This relative nucleophilicity of pyridines and pyridine-N-oxides is similar to what is observed in other OAT reactions generating high-valent metal-oxo species.

  18. Method for Fabricating Textured High-Haze ZnO:Al Transparent Conduction Oxide Films on Chemically Etched Glass Substrates.

    PubMed

    Park, Hyeongsik; Nam, Sang-Hun; Shin, Myunghun; Ju, Minkyu; Lee, Youn-Jung; Yu, Jung-Hoon; Jung, Junhee; Kim, Sunbo; Ahn, Shihyun; Boo, Jin-Hyo; Yi, Junsin

    2016-05-01

    We developed a technique for forming textured aluminum-doped zinc oxide (ZnO:Al) transparent conductive oxide (TCO) films on glass substrates, which were etched using a mixture of hydrofluoric (HF) and hydrochloric (HCl) acids. The etching depth and surface roughness increased with an increase in the HF content and the etching time. The HF-based residues produced insoluble hexafluorosilicate anion- and oxide impurity-based semipermeable films, which reduced the etching rate. Using a small amount of HCl dissolved the Ca compounds, helping to fragment the semipermeable film. This formed random, complex structures on the glass substrates. The angled deposition of three layers of ZnO:Al led to the synthesis of multiscaled ZnO:Al textures on the glass substrates. The proposed approach resulted in textured ZnO:Al TCO films that exhibited high transmittance (-80%) and high haze (> 40%) values over wavelengths of 400-1000 nm, as well as low sheet resistances (< 18 Ω/sq)..Si tandem solar cells based on the ZnO:Al textured TCO films exhibited photocurrents and cell efficiencies that were 40% higher than those of cells with conventional TCO films. PMID:27483840

  19. Multi-laminated copper nanoparticles deposited on conductive substrates for electrocatalytic oxidation of methanol in alkaline electrolytes

    NASA Astrophysics Data System (ADS)

    Xia, Lun-Peng; Guo, Peng; Wang, Yan; Ding, Shi-Qi; He, Jian-Bo

    2014-09-01

    A simple electrodeposition approach to grow multi-laminated copper particles on two conductive substrates is presented. Morphological and structural characterization was performed using SEM and XRD. The copper crystallites are preferentially oriented with {111} planes parallel to the substrate surfaces, providing an optimum interface for methanol oxidation. There are a large number of edges, corners, and atomic steps around individual multi-laminated nanostructured particles. The excellent electrocatalytic activity of the particles to methanol oxidation in alkaline solutions is demonstrated by cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry. The presence of the conductive poly(2-amino-5-mercapto-1,3,4-thiadiazole) interlayer between the Cu particles and the carbon paste substrate results in larger specific surface areas of the particles and smaller charge-transfer resistances of methanol oxidation reaction in the lower potential range. Such an anisotropic laminated structure of non-noble metal nanomaterials deserves further investigation for finding a suitable alternative to noble metal-based anodic catalysts in fuel cells.

  20. Generic process for preparing a crystalline oxide upon a group IV semiconductor substrate

    DOEpatents

    McKee, Rodney A.; Walker, Frederick J.; Chisholm, Matthew F.

    2000-01-01

    A process for growing a crystalline oxide epitaxially upon the surface of a Group IV semiconductor, as well as a structure constructed by the process, is described. The semiconductor can be germanium or silicon, and the crystalline oxide can generally be represented by the formula (AO).sub.n (A'BO.sub.3).sub.m in which "n" and "m" are non-negative integer repeats of planes of the alkaline earth oxides or the alkaline earth-containing perovskite oxides. With atomic level control of interfacial thermodynamics in a multicomponent semiconductor/oxide system, a highly perfect interface between a semiconductor and a crystalline oxide can be obtained.

  1. Superhydrophobic SERS Substrates Based on Silver-Coated Reduced Graphene Oxide Gratings Prepared by Two-Beam Laser Interference.

    PubMed

    Yan, Zhao-Xu; Zhang, Yong-Lai; Wang, Wei; Fu, Xiu-Yan; Jiang, Hao-Bo; Liu, Yu-Qing; Verma, Prabhat; Kawata, Satoshi; Sun, Hong-Bo

    2015-12-16

    Reported here is the fabrication of reduced graphene oxide (RGO) grating structures by two-beam laser interference (TBLI) for the development of highly efficient SERS substrates via simple physical vapor deposition (PVD) coating of silver. TBLI has been utilized to make hierarchical RGO grating structures with microscale gratings and nanoscale folders through a laser treatment induced ablation and photoreduction process. The hierarchical structures contribute to the formation of plasmonic structures after silver coating, giving rise to the formation of plenty of SERS "hot spots", while the RGO substrate would provide chemical enhancement of Raman signal through interaction with analytes molecules. The significantly increased roughness with respect to the hierarchical structures in combination with the removal of hydrophilic oxygen-containing groups endow the resultant substrates with unique superhydrophobicity, which leads to the enrichment of analytes and further lowers the detection limit. The synergistic effects make the silver coated RGO gratings a highly efficient SERS substrate; in the detection of Rhodamine B, our SERS substrates showed high SERS enhancement and good reproducibility, a detection limit of 10(-10) M has been achieved. PMID:26595745

  2. Growth of tin oxide thin films composed of nanoparticles on hydrophilic and hydrophobic glass substrates by spray pyrolysis technique

    NASA Astrophysics Data System (ADS)

    Paloly, Abdul Rasheed; Satheesh, M.; Martínez-Tomás, M. Carmen; Muñoz-Sanjosé, Vicente; Rajappan Achary, Sreekumar; Bushiri, M. Junaid

    2015-12-01

    In this paper, we have demonstrated the growth of tin oxide (SnO2) thin films composed of nanoparticles on hydrophobic (siliconized) and hydrophilic (non-siliconized) glass substrates by using the spray pyrolysis technique. X-ray diffraction (XRD) analysis confirmed the formation of SnO2 thin films with tetragonal rutile-phase structure. Average particle size of nanoparticles was determined to be in the range of 3-4 nm measured from the front view images obtained by a field emission gun scanning electron microscope (FESEM), while the size of nanoparticle clusters, when present, were in the range of 11-20 nm. Surface morphology of SnO2 films grown over hydrophobic substrates revealed larger isolated particles which are less crowded compared to the highly crowded and agglomerated smaller particles in films on hydrophilic substrates. Blue shift in the band gap is observed in samples in which the average particle size is slightly larger than the exciton Bohr radius. Photoluminescence (PL) analysis of samples grown over hydrophobic substrates exhibited an intense defect level emission and a weak near band edge emission. The enhanced visible emission from these SnO2 thin films is attributed to lattice defects formed during the film growth due to the mismatch between the film and the hydrophobic substrate surface.

  3. A colorimetric sensor based on anodized aluminum oxide (AAO) substrate for the detection of nitroaromatics.

    SciTech Connect

    Liu, Y.; Wang, H. H.; Indacochea, J. E.; Wang, M. L.

    2011-12-15

    Simple and low cost colorimetric sensors for explosives detection were explored and developed. Anodized aluminum oxide (AAO) with large surface area through its porous structure and light background color was utilized as the substrate for colorimetric sensors. Fabricated thin AAO films with thickness less than {approx} 500 nm allowed us to observe interference colors which were used as the background color for colorimetric detection. AAO thin films with various thickness and pore-to-pore distance were prepared through anodizing aluminum foils at different voltages and times in dilute sulfuric acid. Various interference colors were observed on these samples due to their difference in structures. Accordingly, suitable anodization conditions that produce AAO samples with desired light background colors for optical applications were obtained. Thin film interference model was applied to analyze the UV-vis reflectance spectra and to estimate the thickness of the AAO membranes. We found that the thickness of produced AAO films increased linearly with anodization time in sulfuric acid. In addition, the growth rate was higher for AAO anodized using higher voltages. The thin film interference formulism was further validated with a well established layer by layer deposition technique. Coating poly(styrene sulfonate) sodium salt (PSS) and poly(allylamine hydrochloride) (PAH) layer by layer on AAO thin film consistently shifted its surface color toward red due to the increase in thickness. The red shift of UV-vis reflectance was correlated quantitatively to the number of layers been assembled. This sensitive red shift due to molecular attachment (increase in thickness) on AAO substrate was applied toward nitroaromatics detection. Aminopropyltrimethoxysilane (APTS) which can be attached onto AAO nanowells covalently through silanization and attract TNT molecules was coated and applied for TNT detection. UV-vis spectra of AAO with APTS shifted to the longer wavelength side due to

  4. Development and Comparison of the Substrate Scope of Pd-Catalysts for the Aerobic Oxidation of Alcohols

    PubMed Central

    Schultz, Mitchell J.; Hamilton, Steven S.; Jensen, David R.; Sigman, Matthew S.

    2009-01-01

    Three catalysts for aerobic oxidation of alcohols are discussed and the effectiveness of each is evaluated for allylic, benzylic, aliphatic, and functionalized alcohols. Additionally, chiral nonracemic substrates as well as chemoselective and diastereoselective oxidations are investigated. In this study, the most convenient system for the Pd-catalyzed aerobic oxidation of alcohols is Pd(OAc)2 in combination with triethylamine. This system functions effectively for the majority of alcohols tested and uses mild conditions (3 to 5 mol % of catalyst, room temperature). Pd(IiPr)(OAc)2(H2O) (1) also successfully oxidizes the majority of alcohols evaluated. This system has the advantage of significantly lowering catalyst loadings but requires higher temperatures (0.1 to 1 mol % of catalyst, 60 °C). A new catalyst is also disclosed, Pd(IiPr)(OPiv)2 (2). This catalyst operates under very mild conditions (1 mol %, room temperature, and air as the O2 source) but with a more limited substrate scope. PMID:15844968

  5. Catalytic transformations of biomass substrates using mixed metal oxides derived from substituted hydrotalcites

    NASA Astrophysics Data System (ADS)

    Macala, Gerald Stephen, II

    Fueled by seemingly endless reserves of cheap and easily accessible fossil energy, the industrial age has brought to the developed world tremendous advances in human health and well being. Unfortunately the burning of fossil fuels has also been implicated in increasing atmospheric CO2 concentrations and global climate change. Concerns about short-term and long-term supply further build a case for the need for alternative energy sources. Biomass derived materials are a tantalizing source of fuels and fine chemicals. Unlike petroleum derived hydrocarbons, biomass can be both renewable and carbon neutral. Crops can be regenerated annually or even more often in tropical climates, and since the captured carbon originates as atmospheric CO2, the overall cycle has the potential to be nearly carbon neutral regardless of the final fate of the carbon. In contrast to petroleum derived hydrocarbons, which can often be made more valuable by adding functionality, biomass derived materials are already highly functionalized and can usually be made more valuable by selective removal of functionality. The development of robust catalysts capable of selective defuntionalization of biomass derived substrates remains an important challenge with potentially enormous economic and societal impact. In addition to being robust and selective, catalysts should preferably be heterogeneous to allow for easier removal and regeneration after the reaction is complete. New materials consisting of Mg-Al hydrotalcite-like structures, with a limiting percentage of Mg or Al substituted with other M2+ or M3+ cations, were synthesized by a co-precipitation process in basic aqueous solution with carbonate as counterion. Calcination of these materials at 460 °C resulted in evolution of CO2 and water and yielded high surface area mixed metal oxides with enhanced reactivity. Materials were characterized by ICP for elemental analysis, XRD for structural information, XPS for surface elemental analysis and TEM

  6. Synthesis of gallium nitride nanostructures by nitridation of electrochemically deposited gallium oxide on silicon substrate

    PubMed Central

    2014-01-01

    Gallium nitride (GaN) nanostructures were successfully synthesized by the nitridation of the electrochemically deposited gallium oxide (Ga2O3) through the utilization of a so-called ammoniating process. Ga2O3 nanostructures were firstly deposited on Si substrate by a simple two-terminal electrochemical technique at a constant current density of 0.15 A/cm2 using a mixture of Ga2O3, HCl, NH4OH and H2O for 2 h. Then, the deposited Ga2O3 sample was ammoniated in a horizontal quartz tube single zone furnace at various ammoniating times and temperatures. The complete nitridation of Ga2O3 nanostructures at temperatures of 850°C and below was not observed even the ammoniating time was kept up to 45 min. After the ammoniating process at temperature of 900°C for 15 min, several prominent diffraction peaks correspond to hexagonal GaN (h-GaN) planes were detected, while no diffraction peak of Ga2O3 structure was detected, suggesting a complete transformation of Ga2O3 to GaN. Thus, temperature seems to be a key parameter in a nitridation process where the deoxidization rate of Ga2O3 to generate gaseous Ga2O increase with temperature. The growth mechanism for the transformation of Ga2O3 to GaN was proposed and discussed. It was found that a complete transformation can not be realized without a complete deoxidization of Ga2O3. A significant change of morphological structures takes place after a complete transformation of Ga2O3 to GaN where the original nanorod structures of Ga2O3 diminish, and a new nanowire-like GaN structures appear. These results show that the presented method seems to be promising in producing high-quality h-GaN nanostructures on Si. PMID:25593562

  7. Method For Improving The Oxidation Resistance Of Metal Substrates Coated With Thermal Barrier Coatings

    DOEpatents

    Thompson, Anthony Mark; Gray, Dennis Michael; Jackson, Melvin Robert

    2003-05-13

    A method for providing a protective coating on a metal-based substrate is disclosed. The method involves the application of an aluminum-rich mixture to the substrate to form a discontinuous layer of aluminum-rich particles, followed by the application of a second coating over the discontinuous layer of aluminum-rich particles. Aluminum diffuses from the aluminum-rich layer into the substrate, and into any bond coat layer which is subsequently applied. Related articles are also described. A method for providing a protective coating on a metal-based substrate is disclosed. The method involves the application of an aluminum-rich mixture to the substrate to form a discontinuous layer of aluminum-rich particles, followed by the application of a second coating over the discontinuous layer of aluminum-rich particles. Aluminum diffuses from the aluminum-rich layer into the substrate, and into any bond coat layer which is subsequently applied. Related articles are also described.

  8. Identification of Novel in vivo MAP Kinase Substrates in Arabidopsis thaliana Through Use of Tandem Metal Oxide Affinity Chromatography*

    PubMed Central

    Hoehenwarter, Wolfgang; Thomas, Martin; Nukarinen, Ella; Egelhofer, Volker; Röhrig, Horst; Weckwerth, Wolfram; Conrath, Uwe; Beckers, Gerold J. M.

    2013-01-01

    Mitogen-activated protein kinase (MPK) cascades are important for eukaryotic signal transduction. They convert extracellular stimuli (e.g. some hormones, growth factors, cytokines, microbe- or damage-associated molecular patterns) into intracellular responses while at the same time amplifying the transmitting signal. By doing so, they ensure proper performance, and eventually survival, of a given organism, for example in times of stress. MPK cascades function via reversible phosphorylation of cascade components MEKKs, MEKs, and MPKs. In plants the identity of most MPK substrates remained elusive until now. Here, we provide a robust and powerful approach to identify and quantify, with high selectivity, site-specific phosphorylation of MPK substrate candidates in the model plant Arabidopsis thaliana. Our approach represents a two-step chromatography combining phosphoprotein enrichment using Al(OH)3-based metal oxide affinity chromatography, tryptic digest of enriched phosphoproteins, and TiO2-based metal oxide affinity chromatography to enrich phosphopeptides from complex protein samples. When applied to transgenic conditional gain-of-function Arabidopsis plants supporting in planta activation of MPKs, the approach allows direct measurement and quantification ex vivo of site-specific phosphorylation of several reported and many yet unknown putative MPK substrates in just a single experiment. PMID:23172892

  9. Process for the deposition of high temperature stress and oxidation resistant coatings on silicon-based substrates

    DOEpatents

    Sarin, Vinod K.

    1991-01-01

    A process for depositing a high temperature stress and oxidation resistant coating on a silicon nitride- or silicon carbide-based substrate body. A gas mixture is passed over the substrate at about 900.degree.-1500.degree. C. and about 1 torr to about ambient pressure. The gas mixture includes one or more halide vapors with other suitable reactant gases. The partial pressure ratios, flow rates, and process times are sufficient to deposit a continuous, fully dense, adherent coating. The halide and other reactant gases are gradually varied during deposition so that the coating is a graded coating of at least two layers. Each layer is a graded layer changing in composition from the material over which it is deposited to the material of the layer and further to the material, if any, deposited thereon, so that no clearly defined compositional interfaces exist. The gases and their partial pressures are varied according to a predetermined time schedule and the halide and other reactant gases are selected so that the layers include (a) an adherent, continuous intermediate layer about 0.5-20 microns thick of an aluminum nitride or an aluminum oxynitride material, over and chemically bonded to the substrate body, and (b) an adherent, continuous first outer layer about 0.5-900 microns thick including an oxide of aluminum or zirconium over and chemically bonded to the intermediate layer.

  10. Process for the deposition of high temperature stress and oxidation resistant coatings on silicon-based substrates

    DOEpatents

    Sarin, V.K.

    1991-07-30

    A process is disclosed for depositing a high temperature stress and oxidation resistant coating on a silicon nitride- or silicon carbide-based substrate body. A gas mixture is passed over the substrate at about 900--1500 C and about 1 torr to about ambient pressure. The gas mixture includes one or more halide vapors with other suitable reactant gases. The partial pressure ratios, flow rates, and process times are sufficient to deposit a continuous, fully dense, adherent coating. The halide and other reactant gases are gradually varied during deposition so that the coating is a graded coating of at least two layers. Each layer is a graded layer changing in composition from the material over which it is deposited to the material of the layer and further to the material, if any, deposited thereon, so that no clearly defined compositional interfaces exist. The gases and their partial pressures are varied according to a predetermined time schedule and the halide and other reactant gases are selected so that the layers include (a) an adherent, continuous intermediate layer about 0.5-20 microns thick of an aluminum nitride or an aluminum oxynitride material, over and chemically bonded to the substrate body, and (b) an adherent, continuous first outer layer about 0.5-900 microns thick including an oxide of aluminum or zirconium over and chemically bonded to the intermediate layer.

  11. Investigation for surface resistance of yttrium-barium-copper-oxide thin films on various substrates for microwave applications

    NASA Astrophysics Data System (ADS)

    Yao, Hongjun

    High temperature superconducting (HTS) materials such as YBCO (Yttrium-Barium-Copper-Oxide) are very attractive in microwave applications because of their extremely low surface resistance. In the proposed all-HTS tunable filter, a layer of HTS thin film on a very thin substrate (100 mum) is needed to act as the toractor that can be rotated to tune the frequency. In order to provide more substrate candidates that meet both electrical and mechanical requirements for this special application, surface resistance of YBCO thin films on various substrates was measured using microstrip ring resonator method. For alumina polycrystalline substrate, a layer of YSZ (Yttrium stabilized Zirconia) was deposited using IBAD (ion beam assisted deposition) method prior to YBCO deposition. The surface resistance of the YBCO thin film on alumina was found to be 22 mO due to high-angle grain boundary problem caused by the mixed in-plane orientations and large FWHM (full width at half maximum) of the thin film. For YBCO thin films on a YSZ single crystal substrate, the surface resistance showed even higher value of 30 mO because of the mixed in-plane orientation problem. However, by annealing the substrate in 200 Torr oxygen at 730°C prior to deposition, the in-plane orientation of YBCO thin films can be greatly improved. Therefore, the surface resistance decreased to 1.4 mO, which is still more than an order higher than the reported best value. The YBCO thin films grown on LaAlO3 single crystal substrate showed perfect in-plane orientation with FWHM less 1°. The surface resistance was as low as 0.032 mO. A tunable spiral resonator made of YBCO thin film on LaAlO3 single crystal substrate demonstrated that the resonant frequency can be tuned in a rang as large as 500 MHz by changing the gap between toractor and substrate. The Q-factor was more than 12,000, which ensured the extraordinarily high sensitivity for the proposed all-HTS tunable filter.

  12. Laser-induced dehydration of graphite oxide coatings on polymer substrates

    SciTech Connect

    Longo, Angela Palomba, Mariano; Carotenuto, Gianfranco; Nicolais, Luigi; Orabona, Emanuele; Maddalena, Pasqualino; Ambrosio, Antonio

    2014-05-15

    Nanosized graphite has been oxidized by the Hummers method to give high quality graphite oxide. This reaction is characterized by a very fast kinetic behavior and a high yield. The produced graphite oxide has been conveniently used to pattern graphene by using a standard photolithographic method, and the resulting systems have been characterized by optical microscopy (OM), scanning electron microscopy (SEM) and by Fourier transform infrared spectroscopy (FT-IR) and Visible-Near Infrared spectroscopy (Vis-NIR)

  13. Facile fabrication of Ag dendrite-integrated anodic aluminum oxide membrane as effective three-dimensional SERS substrate

    NASA Astrophysics Data System (ADS)

    Zhang, Cong-yun; Lu, Ya; Zhao, Bin; Hao, Yao-wu; Liu, Ya-qing

    2016-07-01

    A novel surface enhanced Raman scattering (SERS)-active substrate has been successfully developed, where Ag-dendrites are assembled on the surface and embedded in the channels of anodic aluminum oxide (AAO) membrane, via electrodeposition in AgNO3/PVP aqueous system. Reaction conditions were systematically investigated to attain the best Raman enhancement. The growth mechanism of Ag dendritic nanostructures has been proposed. The Ag dendrite-integrated AAO membrane with unique hierarchical structures exhibits high SERS activity for detecting rhodamine 6G with a detection limit as low as 1 × 10-11 M. Furthermore, the three-dimensional (3D) substrates display a good reproducibility with the average intensity variations at the major Raman peak less than 12%. Most importantly, the 3D SERS substrates without any surface modification show an outstanding SERS response for the molecules with weak affinity for noble metal surfaces. The potential application for the detection of polycyclic aromatic hydrocarbons (PAHs) was evaluated with fluoranthene as Raman target molecule and a sensitive SERS detection with a limit down to 10-8 M was reached. The 3D SERS-active substrate shows promising potential for rapid detection of trace organic pollutants even weak affinity molecules in the environment.

  14. Optimization of substrate-target distance for pulsed laser deposition of tungsten oxide thin films using Langmuir probe

    NASA Astrophysics Data System (ADS)

    Panda, A. Kumar; Singh, A.; Thirumurugesan, R.; Kuppusami, P.; Mohandas, E.

    2015-09-01

    The paper investigates the spatial and temporal variation of laser produced plasma of tungsten oxide using a Langmuir probe. The plasma was produced by laser ablation of tungsten oxide target using an Excimer laser of wavelength 248 nm. Our experimental studies confirmed that oxygen partial pressure (P) of 2× 10-2 mbar is sufficient enough to get stoichiometric tungsten oxide thin films and the plume dynamics was diagnosed for their spatial and temporal behaviour at the above optimised oxygen pressure. Spatial distribution was recorded with the target to substrate distance (D) ranging from the target position to a distance of 75 mm away from the target, whereas the temporal variation was taken in the range of 0-50 μ S with an interval of 0.5 μ S. The average electron densities were found to be maximum at 30 mm from the target position. However, ion density was constant beyond the probe distance of 45 mm from the target. The plasma current was found to be maximum at 28 μ S. The target to substrate distance was optimized for homogenous adherent good quality thin films using plasma parameters such as ion density and average electron density obtained at different oxygen pressure. The target distance and background gas pressure were correlated as PD scaling law and fitted as PD3 in the model.

  15. Role of surfactant-mediated electrodeposited titanium oxide substrate in improving electrocatalytic features of supported platinum particles

    NASA Astrophysics Data System (ADS)

    Spătaru, Tanţa; Preda, Loredana; Osiceanu, Petre; Munteanu, Cornel; Anastasescu, Mihai; Marcu, Maria; Spătaru, Nicolae

    2014-01-01

    A new hybrid system with improved photocatalytic and electrocatalytic performances was obtained by two-step potentiostatic deposition on highly boron-doped diamond (BDD) substrate. First, hydrated TiO2 was anodically deposited from a TiCl3 aqueous solution, both in the presence and in the absence of sodium dodecyl sulfate (SDS). The study of the UV irradiation effect evidenced that titanium oxide coatings obtained by surfactant-assisted electrodeposition (TiO2:SDS) exhibit enhanced photocurrent, due to its very rough texture and presumably to better efficiency of charge carrier separation. Electrochemical deposition of platinum on the oxide-coated BDD was carried out in a second step and AFM, SEM and XPS measurements have shown that, on the TiO2:SDS substrate, Pt particles are smaller, more uniformly distributed, and tend to form clusters, leading to a specific surface area of the electrocatalyst of ca. 6.55 m2 g-1. Carbon monoxide stripping experiments demonstrated that, when deposited on TiO2:SDS, Pt particles are also less sensitive to CO-poisoning during methanol anodic oxidation.

  16. Oxide mediated liquid-solid growth of high aspect ratio aligned gold silicide nanowires on Si(110) substrates.

    PubMed

    Bhatta, Umananda M; Rath, Ashutosh; Dash, Jatis K; Ghatak, Jay; Yi-Feng, Lai; Liu, Chuan-Pu; Satyam, P V

    2009-11-18

    Silicon nanowires grown using the vapor-liquid-solid method are promising candidates for nanoelectronics applications. The nanowires grow from an Au-Si catalyst during silicon chemical vapor deposition. In this paper, the effect of temperature, oxide at the interface and substrate orientation on the nucleation and growth kinetics during formation of nanogold silicide structures is explained using an oxide mediated liquid-solid growth mechanism. Using real time in situ high temperature transmission electron microscopy (with 40 ms time resolution), we show the formation of high aspect ratio ( approximately 15.0) aligned gold silicide nanorods in the presence of native oxide at the interface during in situ annealing of gold thin films on Si(110) substrates. Steps observed in the growth rate and real time electron diffraction show the existence of liquid Au-Si nano-alloy structures on the surface besides the un-reacted gold nanostructures. These results might enable us to engineer the growth of nanowires and similar structures with an Au-Si alloy as a catalyst. PMID:19843987

  17. Oxide mediated liquid-solid growth of high aspect ratio aligned gold silicide nanowires on Si(110) substrates

    NASA Astrophysics Data System (ADS)

    Bhatta, Umananda M.; Rath, Ashutosh; Dash, Jatis K.; Ghatak, Jay; Yi-Feng, Lai; Liu, Chuan-Pu; Satyam, P. V.

    2009-11-01

    Silicon nanowires grown using the vapor-liquid-solid method are promising candidates for nanoelectronics applications. The nanowires grow from an Au-Si catalyst during silicon chemical vapor deposition. In this paper, the effect of temperature, oxide at the interface and substrate orientation on the nucleation and growth kinetics during formation of nanogold silicide structures is explained using an oxide mediated liquid-solid growth mechanism. Using real time in situ high temperature transmission electron microscopy (with 40 ms time resolution), we show the formation of high aspect ratio (≈15.0) aligned gold silicide nanorods in the presence of native oxide at the interface during in situ annealing of gold thin films on Si(110) substrates. Steps observed in the growth rate and real time electron diffraction show the existence of liquid Au-Si nano-alloy structures on the surface besides the un-reacted gold nanostructures. These results might enable us to engineer the growth of nanowires and similar structures with an Au-Si alloy as a catalyst.

  18. Influence of superalloy substrate roughness on adhesion and oxidation behavior of magnetron-sputtered NiCoCrAlY coatings

    NASA Astrophysics Data System (ADS)

    Li, Zhiming; Qian, Shiqiang; Wang, Wei

    2011-10-01

    The present study has been conducted in order to determine the influence of superalloy substrate roughness on adhesion and oxidation behavior of magnetron-sputtered NiCoCrAlY coatings. Six types of coating samples with different substrate roughness were tested. The surface roughness and real surface area of both the substrates and coatings were studied by atomic force microscopy (AFM) techniques. The scratch tests performed at progressive loads were employed to evaluate the adhesion of the coatings. Cyclic oxidation tests were performed at 1100 °C in air for 50 cycles, each cycle consisting of 1 h heating in the tube furnace followed by 15 min cooling in the open air. The AFM measurements exhibit that the surface roughness of the sputtered NiCoCrAlY coating increases with the increasing of the superalloy substrate roughness. The NiCoCrAlY coatings present slightly lower roughness than the corresponding superalloy substrate. The scratch adhesion tests indicate that the coatings on substrates with a smoother surface possess better adhesion than on those with a rougher surface. Both the real surface area and oxidation weight gain of the coatings decrease with the decreasing of the superalloy substrate roughness. The NiCoCrAlY coating sputtered on the superalloy substrate with lower roughness provides relatively higher antioxidant protection than that provided by the coating with rougher substrate.

  19. Effects of MAR-M247 substrate (modified) composition on coating oxidation coating/substrate interdiffusion. M.S. Thesis. Final Report; [protective coatings for hot section components of gas turbine engines

    NASA Technical Reports Server (NTRS)

    Pilsner, B. H.

    1985-01-01

    The effects of gamma+gamma' Mar-M247 substrate composition on gamma+beta Ni-Cr-Al-Zr coating oxidation and coating/substrate interdiffusion were evaluated. These results were also compared to a prior study for a Ni-Cr-Al-Zr coated gamma Ni-Cr-Al substrate with equivalent Al and Cr atomic percentages. Cyclic oxidation behavior at 1130 C was investigated using change in weight curves. Concentration/distance profiles were measured for Al, Cr, Co, W, and Ta. The surface oxides were examined by X-ray diffraction and scanning electron microscopy. The results indicate that variations of Ta and C concentrations in the substrate do not affect oxidation resistance, while additions of grain boundary strengthening elements (Zr, Hf, B) increase oxidation resistance. In addition, the results indicate that oxidation phenomena in gamma+beta/gamma+gamma' Mar-M247 systems have similar characteristics to the l gamma+beta/gamma Ni-Cr-Al system.

  20. Electrochemical investigation of chromium oxide-coated Ti-6Al-4V and Co-Cr-Mo alloy substrates.

    PubMed

    Swaminathan, Viswanathan; Zeng, Haitong; Lawrynowicz, Daniel; Zhang, Zongtao; Gilbert, Jeremy L

    2011-08-01

    Hard coatings for articulating surfaces of total joint replacements may improve the overall wear resistance. However, any coating approach must take account of changes in corrosion behavior. This preliminary assessment analyzes the corrosion kinetics, impedance and mechanical-electrochemical stability of 100 μm thick plasma sprayed chromium oxide (Cr₂O₃) coatings on bearing surfaces in comparison to the native alloy oxide films on Co-Cr-Mo and Ti-6Al-6V. Cyclic potentiodynamic polarization, electrochemical impedance spectroscopy, and mechanical abrasion under potentiostatic conditions were performed on coated and substrate surfaces in physiological saline. SEM analysis characterized the coating morphology. The results showed that the corrosion current density values of chromium oxide coatings (0.4-1.2 μA/cm²) were of the same order of magnitude as Ti-6Al-4V alloy. Mechanical abrasion did not increase corrosion rates of chromium oxide coatings but did for uncoated Co-Cr-Mo and Ti-6Al-4V. The impedance response of chromium oxide coatings was very different than Co-Cr-Mo and Ti-6Al-4V native oxides characterized by a defected coating model. More of a frequency-independent purely resistive response was seen in mid-frequency range for the coatings (CPE(coat) : 40-280 nF/cm² (rad/s)(1-α) , α: 0.67-0.83) whereas a more capacitive character is seen for Co-Cr-Mo and Ti-6Al-4V (CPE(ox) around 20 μF/cm² (rad/s)(1-α) , α around 0.9). Pores, interparticle gaps and incomplete fusion typical for thermal spray coatings were present in these oxides which could have influenced corrosion resistance. The coating microstructure could have allowed some fluid penetration. Overall, these coatings appear to have suitable corrosion properties for wear surfaces. PMID:21648063

  1. Fabrication of p-type porous silicon nanowire with oxidized silicon substrate through one-step MACE

    SciTech Connect

    Li, Shaoyuan; Ma, Wenhui; Zhou, Yang; Chen, Xiuhua; Xiao, Yongyin; Ma, Mingyu; Wei, Feng; Yang, Xi

    2014-05-01

    In this paper, the simple pre-oxidization process is firstly used to treat the starting silicon wafer, and then MPSiNWs are successfully fabricated from the moderately doped wafer by one-step MACE technology in HF/AgNO{sub 3} system. The PL spectrum of MPSiNWs obtained from the oxidized silicon wafers show a large blue-shift, which can be attributed to the deep Q. C. effect induced by numerous mesoporous structures. The effects of HF and AgNO{sub 3} concentration on formation of SiNWs were carefully investigated. The results indicate that the higher HF concentration is favorable to the growth of SiNWs, and the density of SiNWs is significantly reduced when Ag{sup +} ions concentrations are too high. The deposition behaviors of Ag{sup +} ions on oxidized and unoxidized silicon surface were studied. According to the experimental results, a model was proposed to explain the formation mechanism of porous SiNWs by etching the oxidized starting silicon. - Graphical abstract: Schematic cross-sectional views of PSiNWs array formation by etching oxidized silicon wafer in HF/AgNO{sub 3} solution. (A) At the starting point; (B) during the etching process; and (C) after Ag dendrites remove. - Highlights: • Prior to etching, a simple pre-oxidation is firstly used to treat silicon substrate. • The medially doped p-type MPSiNWs are prepared by one-step MACE. • Deposition behaviors of Ag{sup +} ions on oxidized and unoxidized silicon are studied. • A model is finally proposed to explain the formation mechanism of PSiNWs.

  2. Zinc oxide films chemically grown onto rigid and flexible substrates for TFT applications

    NASA Astrophysics Data System (ADS)

    Suchea, M.; Kornilios, N.; Koudoumas, E.

    2010-10-01

    This contribution presents some preliminary results regarding the use of a chemical route for the growth of good quality ZnO thin films that can be used for the fabrication of thin film transistors (TFTs). The films were grown at rather low temperature (60 °C) on glass and PET substrates using non-aqueous (zinc acetate dihydrate in methanol) precursor solution and their surface morphology, crystalline structure, optical transmittance and electrical characteristics were studied. The study indicated that good quality films with desirable ZnO structure onto rigid and flexible substrates can be obtained, using a simple, cheap, low temperature chemical growth method.

  3. Samarium electrodeposited acetate and oxide thin films on stainless steel substrate characterized by XPS

    DOE PAGESBeta

    Myhre, Kristian; Burns, Jonathan; Meyer, Harry; Sims, Nathan; Boll, Rose

    2016-06-01

    Characterization of a samarium thin film deposited on a stainless steel substrate using molecular electrodeposition was carried out using a Thermo Scientific K-Alpha X-ray photoelectron spectrometer. We studied two types of samarium electrodeposition samples, one as-deposited and one heated to 700 °C in an air flow. Survey scans include peaks coming from the stainless steel substrate, such as Fe and Cr. An X-ray photoelectron spectroscopy (XPS) survey spectrum, Sm 3d, C 1s, and O 1s narrow scans are shown. It was determined that the heating process decomposed the deposited Sm acetate to Sm2O3 using XPS.

  4. Crossed ferric oxide nanosheets supported cobalt oxide on 3-dimensional macroporous Ni foam substrate used for diesel soot elimination under self-capture contact mode

    NASA Astrophysics Data System (ADS)

    Cao, Chunmei; Li, Xingang; Zha, Yuqing; Zhang, Jing; Hu, Tiandou; Meng, Ming

    2016-03-01

    Crossed Fe2O3 nanosheets supported cobalt oxide nanoparticles on three-dimensionally macroporous nickel foam substrate (xCo/Fe-NF) was designed and successfully prepared through a facile hydrothermal and impregnation route. These catalysts showed high catalytic soot combustion activities under self-capture contact mode. The three-dimensional macroporous structures of Ni foam and the crossed Fe2O3 nanosheets constituted macroporous voids can greatly increase the contact efficiency between soot particulates and catalysts. The interaction between Co and Fe facilitated the activation of the Fe-O bond and increased the amounts of active oxygen species, thus improving the redox property of the catalysts. The 0.6Co/Fe-NF catalyst exhibited the highest turnover frequency (TOF) for soot combustion, which is in good accordance with the largest amount of active oxygen species. Based upon the catalytic performance and multiple characterization results, two reaction pathways for soot oxidation are identified, namely, the direct oxidation by the activated oxygen species via oxygen vacancies and the NOx-aided soot oxidation.Crossed Fe2O3 nanosheets supported cobalt oxide nanoparticles on three-dimensionally macroporous nickel foam substrate (xCo/Fe-NF) was designed and successfully prepared through a facile hydrothermal and impregnation route. These catalysts showed high catalytic soot combustion activities under self-capture contact mode. The three-dimensional macroporous structures of Ni foam and the crossed Fe2O3 nanosheets constituted macroporous voids can greatly increase the contact efficiency between soot particulates and catalysts. The interaction between Co and Fe facilitated the activation of the Fe-O bond and increased the amounts of active oxygen species, thus improving the redox property of the catalysts. The 0.6Co/Fe-NF catalyst exhibited the highest turnover frequency (TOF) for soot combustion, which is in good accordance with the largest amount of active oxygen

  5. Ultrasensitive Strain Sensor Produced by Direct Patterning of Liquid Crystals of Graphene Oxide on a Flexible Substrate.

    PubMed

    Coskun, M Bulut; Akbari, Abozar; Lai, Daniel T H; Neild, Adrian; Majumder, Mainak; Alan, Tuncay

    2016-08-31

    Ultrasensitive flexible strain sensors were developed through the combination of shear alignment of a high concentration graphene oxide (GO) dispersion with fast and precise patterning of multiple rectangular features on a flexible substrate. Resistive changes in the reduced GO films were investigated under various uniaxial strain cycles ranging from 0.025 to 2%, controlled with a motorized nanopositioning stage. The devices uniquely combine a very small detection limit (0.025%) and a high gauge factor with a rapid fabrication process conducive to batch production. PMID:27490520

  6. Versatile Oxidation Methods for Organic and Inorganic Substrates Catalyzed by Platinum-Group Metals on Carbons.

    PubMed

    Sawama, Yoshinari; Asai, Shota; Monguchi, Yasunari; Sajiki, Hironao

    2016-02-01

    Platinum-group metals on activated carbon catalysts, represented by Pd/C, Ru/C, Rh/C, etc., are widely utilized to accomplish green and sustainable organic reactions due to their favorable features, such as easy handling, recoverability, and reusability. The efficient oxidation methods of various organic compounds using heterogeneous platinum-group metals on carbons with or without added oxidants are summarized in this Personal Account. The oxidation of internal alkynes into diketones was effectively catalyzed by Pd/C in the presence of dimethyl sulfoxide and molecular oxygen or pyridine N-oxide. The Pd/C-catalyzed mild combustion of gaseous hydrogen with molecular oxygen provided hydrogen peroxide, which could be directly utilized for the oxidation of sulfide derivatives into sulfoxides. Furthermore, the Ru/C-catalyzed aerobic oxidation of primary and secondary alcohols gave the corresponding aldehydes and ketones, respectively. On the other hand, the dehydrogenative oxidation of secondary alcohols into ketones was achieved using Rh/C in water, and primary alcohols were effectively dehydrogenated by Pd/C in water under mildly reduced pressure to produce carboxylic acids. PMID:26666634

  7. Self-aligned graphene field-effect transistors on SiC (0001) substrates with self-oxidized gate dielectric

    NASA Astrophysics Data System (ADS)

    Jia, Li; Cui, Yu; Li, Wang; Qingbin, Liu; Zezhao, He; Shujun, Cai; Zhihong, Feng

    2014-07-01

    A scalable self-aligned approach is employed to fabricate monolayer graphene field-effect transistors on semi-insulated 4H-SiC (0001) substrates. The self-aligned process minimized access resistance and parasitic capacitance. Self-oxidized Al2O3, formed by deposition of 2 nm Al followed by exposure in air to be oxidized, is used as gate dielectric and shows excellent insulation. An intrinsic cutoff frequency of 34 GHz and maximum oscillation frequency of 36.4 GHz are realized for the monolayer graphene field-effect transistor with a gate length of 0.2 μm. These studies show a pathway to fabricate graphene transistors for future applications in ultra-high frequency circuits.

  8. Atomic layer deposition of ultrathin blocking layer for low-temperature solid oxide fuel cell on nanoporous substrate

    SciTech Connect

    Yu, Wonjong; Cho, Gu Young; Noh, Seungtak; Tanveer, Waqas Hassan; Cha, Suk Won; Ji, Sanghoon; An, Jihwan

    2015-01-15

    An ultrathin yttria-stabilized zirconia (YSZ) blocking layer deposited by atomic layer deposition (ALD) was utilized for improving the performance and reliability of low-temperature solid oxide fuel cells (SOFCs) supported by an anodic aluminum oxide substrate. Physical vapor-deposited YSZ and gadolinia-doped ceria (GDC) electrolyte layers were deposited by a sputtering method. The ultrathin ALD YSZ blocking layer was inserted between the YSZ and GDC sputtered layers. To investigate the effects of an inserted ultrathin ALD blocking layer, SOFCs with and without an ultrathin ALD blocking layer were electrochemically characterized. The open circuit voltage (1.14 V) of the ALD blocking-layered SOFC was visibly higher than that (1.05 V) of the other cell. Furthermore, the ALD blocking layer augmented the power density and improved the reproducibility.

  9. Sn and Cu oxide nanoparticles deposited on TiO2 nanoflower 3D substrates by Inert Gas Condensation technique

    NASA Astrophysics Data System (ADS)

    Kusior, A.; Kollbek, K.; Kowalski, K.; Borysiewicz, M.; Wojciechowski, T.; Adamczyk, A.; Trenczek-Zajac, A.; Radecka, M.; Zakrzewska, K.

    2016-09-01

    Sn and Cu oxide nanoparticles were deposited by Inert Gas Condensation (IGC) technique combined with dc magnetron sputtering onto nanoflower TiO2 3D substrates obtained in the oxidation process of Ti-foil in 30% H2O2. Sputtering parameters such as insertion length and Ar/He flow rates were optimized taking into account the nanostructure morphology. Comparative studies with hydrothermal method were carried out. Surface properties of the synthesized nanomaterials were studied by Scanning Electron Microscopy, SEM, Atomic Force Microscopy, AFM, and X-ray Photoelectron Spectroscopy, XPS. X-ray diffraction, XRD and Raman spectroscopy were performed in order to determine phase composition. Impedance spectroscopy demonstrated the influence of nanoparticles on the electrical conductivity.

  10. High critical current density YBa 2Cu 3O 7- δ films on surface-oxidized metallic substrates

    NASA Astrophysics Data System (ADS)

    Matsumoto, Kaname; Kim, SeokBeom; Yamagiwa, Katsuya; Koike, Yoshihiro; Hirabayashi, Izumi; Watanabe, Tomonori; Uno, Naoki; Ikeda, Masaru

    2000-06-01

    YBa 2Cu 3O 7-δ (YBCO) films with high critical current density ( Jc) were fabricated on nickel tapes buffered with bi-axially textured NiO prepared by surface-oxidation epitaxy (SOE). The effects of oxide cap layers, such as YSZ, CeO 2 and MgO, on the SOE-grown NiO were investigated to improve the superconducting properties of the YBCO films on NiO. By inserting a thin MgO cap layer between NiO layer and YBCO film, a Jc of 3×10 5 A/cm 2 (77 K, 0 T) was achieved. This result indicates the potentiality of the SOE method. In this paper, the application of the NiO/Ni substrate to non-vacuum processings, such as metal-organic deposition (MOD) and liquid phase epitaxy (LPE) will be also introduced.

  11. Multifunctional porous titanium oxide coating with apatite forming ability and photocatalytic activity on a titanium substrate formed by plasma electrolytic oxidation.

    PubMed

    Akatsu, T; Yamada, Y; Hoshikawa, Y; Onoki, T; Shinoda, Y; Wakai, F

    2013-12-01

    Plasma electrolytic oxidation (PEO) was used to make a multifunctional porous titanium oxide (TiO2) coating on a titanium substrate. The key finding of this study is that a highly crystalline TiO2 coating can be made by performing the PEO in an ammonium acetate (CH3COONH4) solution; the PEO coating was formed by alternating between rapid heating by spark discharges and quenching in the solution. The high crystallinity of the TiO2 led to the surface having multiple functions, including apatite forming ability and photocatalytic activity. Hydroxyapatite formed on the PEO coating when it was soaked in simulated body fluid. The good apatite forming ability can be attributed to the high density of hydroxyl groups on the anatase and rutile phases in the coating. The degradation of methylene blue under ultraviolet radiation indicated that the coating had high photocatalytic activity. PMID:24094199

  12. Oxidation of Phe454 in the Gating Segment Inactivates Trametes multicolor Pyranose Oxidase during Substrate Turnover

    PubMed Central

    Volc, Jindrich; Peterbauer, Clemens K.; Leitner, Christian; Haltrich, Dietmar

    2016-01-01

    The flavin-dependent enzyme pyranose oxidase catalyses the oxidation of several pyranose sugars at position C-2. In a second reaction step, oxygen is reduced to hydrogen peroxide. POx is of interest for biocatalytic carbohydrate oxidations, yet it was found that the enzyme is rapidly inactivated under turnover conditions. We studied pyranose oxidase from Trametes multicolor (TmPOx) inactivated either during glucose oxidation or by exogenous hydrogen peroxide using mass spectrometry. MALDI-MS experiments of proteolytic fragments of inactivated TmPOx showed several peptides with a mass increase of 16 or 32 Da indicating oxidation of certain amino acids. Most of these fragments contain at least one methionine residue, which most likely is oxidised by hydrogen peroxide. One peptide fragment that did not contain any amino acid residue that is likely to be oxidised by hydrogen peroxide (DAFSYGAVQQSIDSR) was studied in detail by LC-ESI-MS/MS, which showed a +16 Da mass increase for Phe454. We propose that oxidation of Phe454, which is located at the flexible active-site loop of TmPOx, is the first and main step in the inactivation of TmPOx by hydrogen peroxide. Oxidation of methionine residues might then further contribute to the complete inactivation of the enzyme. PMID:26828796

  13. Catalyst-Free Synthesis of ZnO Nanowires on Oxidized Silicon Substrate for Gas Sensing Applications.

    PubMed

    Behera, B; Chandra, S

    2015-06-01

    In the present work, we report the synthesis of nanostructured ZnO by oxidation of zinc film without using a seed or catalyst layer. The zinc films were deposited on oxidized Si substrates by RF magnetron sputtering process. These were oxidized in dry and wet air/oxygen ambient. The optimized process yielded long nanowires of ZnO having diameter of around 60-70 nm and spread uniformly over the surface. The effect of oxidation temperature, time, Zn film thickness and the ambient has strong influence on the morphology of resulting nanostruxctured ZnO film. The films were characterized by scanning electron microscopy for morphological studies and X-ray diffraction (XRD) analysis to study the phase of the nanostructured ZnO. Room temperature photoluminescence (PL) measurements of the nanowires show UV and green emission. A sensor was designed and fabricated using nanostructured ZnO film, incorporating inter-digital-electrode (IDE) for the measurement of resistance of the sensing layer. The gas sensing properties were investigated from the measurement of change in resistance when exposed to vapours of different volatile organic compound (VOC) such as acetone, ethanol, methanol and 2-propanol. The results suggest that ZnO nanowires fabricated by this method have potential application in gas sensors. PMID:26369077

  14. COSIM: A Finite-Difference Computer Model to Predict Ternary Concentration Profiles Associated with Oxidation and Interdiffusion of Overlay-Coated Substrates

    NASA Technical Reports Server (NTRS)

    Nesbitt, James A.

    2000-01-01

    A finite-difference computer program (COSIM) has been written which models the one-dimensional, diffusional transport associated with high-temperature oxidation and interdiffusion of overlay-coated substrates. The program predicts concentration profiles for up to three elements in the coating and substrate after various oxidation exposures. Surface recession due to solute loss is also predicted. Ternary cross terms and concentration-dependent diffusion coefficients are taken into account. The program also incorporates a previously-developed oxide growth and spalling model to simulate either isothermal or cyclic oxidation exposures. In addition to predicting concentration profiles after various oxidation exposures, the program can also be used to predict coating fife based on a concentration dependent failure criterion (e.g., surface solute content drops to two percent). The computer code, written in an extension of FORTRAN 77, employs numerous subroutines to make the program flexible and easily modifiable to other coating oxidation problems.

  15. COSIM: A Finite-Difference Computer Model to Predict Ternary Concentration Profiles Associated With Oxidation and Interdiffusion of Overlay-Coated Substrates

    NASA Technical Reports Server (NTRS)

    Nesbitt, James A.

    2001-01-01

    A finite-difference computer program (COSIM) has been written which models the one-dimensional, diffusional transport associated with high-temperature oxidation and interdiffusion of overlay-coated substrates. The program predicts concentration profiles for up to three elements in the coating and substrate after various oxidation exposures. Surface recession due to solute loss is also predicted. Ternary cross terms and concentration-dependent diffusion coefficients are taken into account. The program also incorporates a previously-developed oxide growth and spalling model to simulate either isothermal or cyclic oxidation exposures. In addition to predicting concentration profiles after various oxidation exposures, the program can also be used to predict coating life based on a concentration dependent failure criterion (e.g., surface solute content drops to 2%). The computer code is written in FORTRAN and employs numerous subroutines to make the program flexible and easily modifiable to other coating oxidation problems.

  16. Estimation of the cytoplasmic pH of Coxiella burnetii and effect of substrate oxidation on proton motive force.

    PubMed Central

    Hackstadt, T

    1983-01-01

    The magnitude of the proton motive force generated during in vitro substrate oxidation by Coxiella burnetii was examined. The intracellular pH of C. burnetii varied from about 5.1 to 6.95 in resting cells over an extracellular pH range of 2 to 7. Similarly, delta psi varied from about 15 mV to -58 mV over approximately the same range of extracellular pH. Both components of the proton motive force increased during substrate oxidation, resulting in an increase in proton motive force from about -92 mV in resting cells to -153 mV in cells metabolizing glutamate at pH 4.2. The respiration-dependent increase in proton motive force was blocked by respiratory inhibitors, but the delta pH was not abolished even by the addition of proton ionophores such as carbonyl cyanide-m-chlorophenyl hydrazone or 2,4-dinitrophenol. Because of this apparently passive component of delta pH maintenance, the largest proton motive force was obtained at an extracellular pH too low to permit respiration. C. burnetii appears, therefore, to behave in many respects like other acidophilic bacteria. Such responses are proposed to contribute to the extreme resistance of C. burnetii to environmental conditions and subsequent activation upon entry into the phagolysosome of eucaryotic cells in which this organism multiplies. PMID:6302078

  17. Spontaneous Reduction and Assembly of Graphene oxide into Three-Dimensional Graphene Network on Arbitrary Conductive Substrates

    PubMed Central

    Hu, Chuangang; Zhai, Xiangquan; Liu, Lili; Zhao, Yang; Jiang, Lan; Qu, Liangti

    2013-01-01

    Chemical reduction of graphene oxide (GO) is the main route to produce the mass graphene-based materials with tailored surface chemistry and functions. However, the toxic reducing circumstances, multiple steps, and even incomplete removal of the oxygen-containing groups were involved, and the produced graphenes existed usually as the assembly-absent precipitates. Herein, a substrate-assisted reduction and assembly of GO (SARA-GO) method was developed for spontaneous formation of 3D graphene network on arbitrary conductive substrates including active and inert metals, semiconducting Si, nonmetallic carbon, and even indium-tin oxide glass without any additional reducing agents. The SARA-GO process offers a facile, efficient approach for constructing unique graphene assemblies such as microtubes, multi-channel networks, micropatterns, and allows the fabrication of high-performance binder-free rechargeable lithium-ion batteries. The versatile SARD-GO method significantly improves the processablity of graphenes, which could thus benefit many important applications in sensors and energy-related devices. PMID:23799368

  18. Crossed ferric oxide nanosheets supported cobalt oxide on 3-dimensional macroporous Ni foam substrate used for diesel soot elimination under self-capture contact mode.

    PubMed

    Cao, Chunmei; Li, Xingang; Zha, Yuqing; Zhang, Jing; Hu, Tiandou; Meng, Ming

    2016-03-21

    Crossed Fe2O3 nanosheets supported cobalt oxide nanoparticles on three-dimensionally macroporous nickel foam substrate (xCo/Fe-NF) was designed and successfully prepared through a facile hydrothermal and impregnation route. These catalysts showed high catalytic soot combustion activities under self-capture contact mode. The three-dimensional macroporous structures of Ni foam and the crossed Fe2O3 nanosheets constituted macroporous voids can greatly increase the contact efficiency between soot particulates and catalysts. The interaction between Co and Fe facilitated the activation of the Fe-O bond and increased the amounts of active oxygen species, thus improving the redox property of the catalysts. The 0.6Co/Fe-NF catalyst exhibited the highest turnover frequency (TOF) for soot combustion, which is in good accordance with the largest amount of active oxygen species. Based upon the catalytic performance and multiple characterization results, two reaction pathways for soot oxidation are identified, namely, the direct oxidation by the activated oxygen species via oxygen vacancies and the NOx-aided soot oxidation. PMID:26509240

  19. Influence of defects and processing parameters on the properties of indium tin oxide films on polyethylene napthalate substrate

    SciTech Connect

    Han, H.; Zoo, Yeongseok; Bhagat, S. K.; Lewis, J. S.; Alford, T. L.

    2007-09-15

    Indium tin oxide (ITO) thin films were deposited on polyethylene napthalate (PEN) by rf sputtering using different rf powers (60 and 120 W) and at different substrate temperatures (room temperature and 100 deg. C). Selected PEN substrates were pretreated using an Ar plasma before ITO sputter deposition. Rutherford backscattering spectrometry was used to determine the oxygen content in the films. Hall effect measurements were used to evaluate the electrical properties. In this paper the influence of defect structure, sputtering conditions, and the effect of annealing on the electrical and optical properties of ITO on PEN have been investigated. Electrical properties such as carrier concentration, mobility, and resistivity of the ITO films varied with rf power and substrate temperature. The electrical and optical properties of the films changed after annealing in air. This study also describes how the as-deposited amorphous ITO changes from amorphous to crystalline as a result of heat treatment, and investigates the effects of Sn defect clustering on electrical and optical properties of the ITO films.

  20. Fabrication of SERS-active substrates using silver nanofilm-coated porous anodic aluminum oxide for detection of antibiotics.

    PubMed

    Chen, Jing; Feng, Shaolong; Gao, Fang; Grant, Edward; Xu, Jie; Wang, Shuo; Huang, Qian; Lu, Xiaonan

    2015-04-01

    We have developed a silver nanofilm-coated porous anodic aluminum oxide (AAO) as a surface-enhanced Raman scattering (SERS)-active substrate for the detection of trace level of chloramphenicol, a representative antibiotic in food systems. The ordered aluminum template generated during the synthesis of AAO serves as a patterned matrix on which a coated silver film replicates the patterned AAO matrix to form a 2-dimensional ordered nanostructure. We used atomic force microscopy and scanning electron microscopy images to determine the morphology of this nanosubstrate, and characterized its localized surface plasmon resonance by ultraviolet-visible reflection. We gauged the SERS effect of this nanosubstrate by confocal micro-Raman spectroscopy (782-nm laser), finding a satisfactory and consistent performance with enhancement factors of approximately 2 × 10(4) and a limit of detection for chloramphenicol of 7.5 ppb. We applied principal component analysis to determine the limit of quantification for chloramphenicol of 10 ppb. Using electromagnetic field theory, we developed a detailed mathematical model to explain the mechanism of Raman signal enhancement of this nanosubstrate. With simple sample pretreatment and separation steps, this silver nanofilm-coated AAO substrate could detect 50 ppb chloramphenicol in milk, indicating good potential as a reliable SERS-active substrate for rapid detection of chemical contaminants in agricultural and food products. PMID:25736080

  1. Osteogenic potential of in situ TiO2 nanowire surfaces formed by thermal oxidation of titanium alloy substrate

    NASA Astrophysics Data System (ADS)

    Tan, A. W.; Ismail, R.; Chua, K. H.; Ahmad, R.; Akbar, S. A.; Pingguan-Murphy, B.

    2014-11-01

    Titanium dioxide (TiO2) nanowire surface structures were fabricated in situ by a thermal oxidation process, and their ability to enhance the osteogenic potential of primary osteoblasts was investigated. Human osteoblasts were isolated from nasal bone and cultured on a TiO2 nanowires coated substrate to assess its in vitro cellular interaction. Bare featureless Ti-6Al-4V substrate was used as a control surface. Initial cell adhesion, cell proliferation, cell differentiation, cell mineralization, and osteogenic related gene expression were examined on the TiO2 nanowire surfaces as compared to the control surfaces after 2 weeks of culturing. Cell adhesion and cell proliferation were assayed by field emission scanning electron microscope (FESEM) and Alamar Blue reduction assay, respectively. The nanowire surfaces promoted better cell adhesion and spreading than the control surface, as well as leading to higher cell proliferation. Our results showed that osteoblasts grown onto the TiO2 nanowire surfaces displayed significantly higher production levels of alkaline phosphatase (ALP), extracellular (ECM) mineralization and genes expression of runt-related transcription factor (Runx2), bone sialoprotein (BSP), ostoepontin (OPN) and osteocalcin (OCN) compared to the control surfaces. This suggests the potential use of such surface modification on Ti-6Al-4V substrates as a promising means to improve the osteointegration of titanium based implants.

  2. Ultrafast dynamics of ligand and substrate interaction in endothelial nitric oxide synthase under Soret excitation.

    PubMed

    Hung, Chih-Chang; Yabushita, Atsushi; Kobayashi, Takayoshi; Chen, Pei-Feng; Liang, Keng S

    2016-01-01

    Ultrafast transient absorption spectroscopy of endothelial NOS oxygenase domain (eNOS-oxy) was performed to study dynamics of ligand or substrate interaction under Soret band excitation. Photo-excitation dissociates imidazole ligand in <300fs, then followed by vibrational cooling and recombination within 2ps. Such impulsive bond breaking and late rebinding generate proteinquakes, which relaxes in several tens of picoseconds. The photo excited dynamics of eNOS-oxy with L-arginine substrate mainly occurs at the local site of heme, including ultrafast internal conversion within 400fs, vibrational cooling, charge transfer, and complete ground-state recovery within 1.4ps. The eNOS-oxy without additive is partially bound with water molecule, thus its photoexcited dynamics also shows ligand dissociation in <800fs. Then it followed by vibrational cooling coupled with charge transfer in 4.8ps, and recombination of ligand to distal side of heme in 12ps. PMID:27183248

  3. C-Myc regulates substrate oxidation patterns during early pressure-overload hypertrophy

    SciTech Connect

    Ledee, Dolena R.; Smith, Lincoln; Kajimoto, Masaki; Bruce, Margaret; Isern, Nancy G.; Xu, Chun; Portman, Michael A.; Olson, Aaron

    2013-11-26

    Pressure overload cardiac hypertrophy alters substrate metabolism. Prior work showed that myocardial inactivation of c-Myc (Myc) attenuated hypertrophy and decreased expression of glycolytic genes after aortic constriction. Accordingly, we hypothesize that Myc regulates substrate preferences for the citric acid cycle during pressure overload hypertrophy from transverse aortic constriction (TAC) and that these metabolic changes impact cardiac function and growth. To test this hypothesis, we subjected FVB mice with cardiac specific, inducible Myc inactivation (MycKO-TAC) and non-transgenic littermates (Cont-TAC) to transverse aortic constriction (n=7/group). A separate group underwent sham surgery (Sham, n=5). After two weeks, function was measured in isolated working hearts along with substrate fractional contributions to the citric acid cycle by using perfusate with 13C labeled mixed fatty acids, lactate, ketones and unlabeled glucose and insulin. Western blots were used to evaluate metabolic enzymes. Cardiac function was similar between groups after TAC although +dP/dT and -dP/dT trended towards improvement in MycKO-TAC versus Cont-TAC. Compared to Sham, Cont-TAC had increased free fatty acid fractional contribution with a concurrent decrease in unlabeled (presumably glucose) contribution. Myc inactivation (MycKO-TAC) inhibited these metabolic changes. Hypertrophy in general increased protein levels of PKM2; however this change was not linked to Myc status. Protein post-translation modification by O-GlcNAc was significantly greater in Cont-TAC versus both Sham and MycKO-TAC. In conclusion, Myc regulates substrate utilization during early pressure overload hypertrophy. Our results show that the metabolic switch during hypertrophy is not necessary to maintain cardiac function, but it may be important mechanism to promote cardiomyocyte growth. Myc also regulates protein O-GlcNAcylation during hypertrophy.

  4. Inclined-substrate deposition of biaxially textured magnesium oxide thin films for YBCO coated conductors.

    SciTech Connect

    Ma, B.; Li, M.; Jee, Y. A.; Koritala, R. E.; Fisher, B. L.; Balachandran, U.; Energy Technology

    2002-02-01

    Highly textured MgO films were grown by the inclined-substrate deposition (ISD) technique at a high deposition rate. A columnar grain with a roofing-tile-shaped surface was observed in these MgO films. X-ray pole figure, and {phi}- and {omega}-scan were used to characterize in-plane and out-of-plane textures. MgO films deposited when the incline angle {alpha} was 55 and 30 degrees exhibited the best in-plane and out-of-plane texture, respectively. High-quality YBCO films were epitaxially grown on ISD-MgO-buffered Hastelloy C substrates by pulsed laser deposition. {Tc}=88 K, with sharp transition, and j{sub c} values of {approx}2x10{sup 5} A/cm{sup 2} at 77 K in zero field were observed on films 5 mm wide and 1 cm long. This work has demonstrated that biaxially textured ISD MgO buffer layers deposited on metal substrates are excellent candidates for fabrication of high-quality YBCO coated conductors.

  5. Growth and properties of crystalline barium oxide on the GaAs(100) substrate

    SciTech Connect

    Yasir, M.; Dahl, J.; Lång, J.; Tuominen, M.; Punkkinen, M. P. J.; Laukkanen, P. Kokko, K.; Kuzmin, M.; Korpijärvi, V.-M.; Polojärvi, V.; Guina, M.

    2013-11-04

    Growing a crystalline oxide film on III-V semiconductor renders possible approaches to improve operation of electronics and optoelectronics heterostructures such as oxide/semiconductor junctions for transistors and window layers for solar cells. We demonstrate the growth of crystalline barium oxide (BaO) on GaAs(100) at low temperatures, even down to room temperature. Photoluminescence (PL) measurements reveal that the amount of interface defects is reduced for BaO/GaAs, compared to Al{sub 2}O{sub 3}/GaAs, suggesting that BaO is a useful buffer layer to passivate the surface of the III-V device material. PL and photoemission data show that the produced junction tolerates the post heating around 600 °C.

  6. Impact of high-fat, low-carbohydrate diet on myocardial substrate oxidation, insulin sensitivity, and cardiac function after ischemia-reperfusion.

    PubMed

    Liu, Jian; Wang, Peipei; Douglas, Samuel L; Tate, Joshua M; Sham, Simon; Lloyd, Steven G

    2016-07-01

    High-fat, low-carbohydrate Diet (HFLCD) impairs the myocardial response to ischemia-reperfusion, but the underlying mechanisms remain elusive. We sought to determine the magnitude of diet-induced alterations in intrinsic properties of the myocardium (including insulin sensitivity and substrate oxidation) and circulating substrate and insulin differences resulting from diet, leading to this impaired response. Rats were fed HFLCD (60% kcal from fat/30% protein/10% carbohydrate) or control diet (CONT) (16%/19%/65%) for 2 wk. Isolated hearts underwent global low-flow ischemia followed by reperfusion (I/R). Carbon-13 NMR spectroscopy was used to determine myocardial substrate TCA cycle entry. Myocardial insulin sensitivity was assessed as dose-response of Akt phosphorylation. There was a significant effect of HFLCD and I/R with both these factors leading to an increase in free fatty acid (FFA) oxidation and a decrease in carbohydrate or ketone oxidation. Following I/R, HFLCD led to decreased ketone and increased FFA oxidation; the recovery of left ventricular (LV) function was decreased in HFLCD and was negatively correlated with FFA oxidation and positively associated with ketone oxidation. HFLCD also resulted in reduced insulin sensitivity. Under physiologic ranges, there were no direct effects of buffer insulin and ketone levels on oxidation of any substrate and recovery of cardiac function after I/R. An insulin-ketone interaction exists for myocardial substrate oxidation characteristics. We conclude that the impaired recovery of function after ischemia-reperfusion with HFLCD is largely due to intrinsic diet effects on myocardial properties, rather than to diet effect on circulating insulin or substrate levels. PMID:27199129

  7. Surface engineering of nanoporous substrate for solid oxide fuel cells with atomic layer-deposited electrolyte

    PubMed Central

    Ji, Sanghoon; Tanveer, Waqas Hassan; Yu, Wonjong; Kang, Sungmin; Cho, Gu Young; Kim, Sung Han

    2015-01-01

    Summary Solid oxide fuel cells with atomic layer-deposited thin film electrolytes supported on anodic aluminum oxide (AAO) are electrochemically characterized with varying thickness of bottom electrode catalyst (BEC); BECs which are 0.5 and 4 times thicker than the size of AAO pores are tested. The thicker BEC ensures far more active mass transport on the BEC side and resultantly the thicker BEC cell generates ≈11 times higher peak power density than the thinner BEC cell at 500 °C. PMID:26425432

  8. Surface engineering of nanoporous substrate for solid oxide fuel cells with atomic layer-deposited electrolyte.

    PubMed

    Ji, Sanghoon; Tanveer, Waqas Hassan; Yu, Wonjong; Kang, Sungmin; Cho, Gu Young; Kim, Sung Han; An, Jihwan; Cha, Suk Won

    2015-01-01

    Solid oxide fuel cells with atomic layer-deposited thin film electrolytes supported on anodic aluminum oxide (AAO) are electrochemically characterized with varying thickness of bottom electrode catalyst (BEC); BECs which are 0.5 and 4 times thicker than the size of AAO pores are tested. The thicker BEC ensures far more active mass transport on the BEC side and resultantly the thicker BEC cell generates ≈11 times higher peak power density than the thinner BEC cell at 500 °C. PMID:26425432

  9. Enhancement of Characteristics of Transparent Conductive Electrode on Flexible Substrate by Combination of Solution-Based Oxide and Metallic Layers.

    PubMed

    Hong, Sung-Jei; Kim, Yong-Hoon; Cha, Seung-Jae; Kim, Yong-Sung

    2015-10-01

    This study investigates solution-processed transparent conductors with hybrid structure consisting of silver nanowires (AgNWs) and indium-tin-oxide nanoparticles (ITO-NPs) layers fabricated on polymeric flexible polyethylene terephthalate (PET) substrate. The transparent conductors had stacked structures of AgNWs/ITO-NPs on 125-μm-thick PET and ITO-NPs/AgNWs/ITO-NPs on 125-μm-thick PET, 188-μm-thick PET, or 700-μm-thick glass substrate, respectively. Successful integrations were possible on the substrates without any deformation or distortion. Sheet resistance of the triple-layered transparent conductor samples exhibits low values ranging from 22.41 Ω/square to 22.99 Ω/squarer. Also, their optical transmittance exhibits high values ranging from 83.78 to 87.29% at 550 nm. The triple-layered transparent conductor showed a good thermal stability in terms of sheet resistance and optical transmittance against the high-temperature environment up to 250 °C. All the double and triple-layered transparent conductors fabricated on PET and glass substrates are so stable against the accelerated thermal aging from 110 °C to 130 °C, that ΔR/R0 and ΔT(550)/T0(550) values exhibit less than 0.068 and 0.049, respectively. Furthermore, the layers are so flexible that ΔR/R0 of the layers on PET substrates is lower than 0.1 even at 4.0-mm bending. Especially, triple-layered transparent conductor on 125-μm-thick PET substrates exhibits ΔR/R0 value of 0.042 even at 4.0 mm bending. Thus, it can be concluded that the hybrid structures have the advantage of both thermal stability and flexibility for electrical and optical properties of transparent conductive electrode; which makes them highly applicable in flexible electronics. PMID:26726453

  10. Solution-processed indium-tin-oxide nanoparticle transparent conductors on flexible glass substrate with high optical transmittance and high thermal stability

    NASA Astrophysics Data System (ADS)

    Hong, Sung-Jei; Kim, Sun-Woo; In Han, Jeong

    2014-08-01

    In this study, solution-processed transparent conductors on flexible glass substrate were investigated using indium-tin-oxide (ITO) nanoparticle (NP) ink. The ITO-NP conductors were well fabricated on the flexible glass substrate with neither distortion nor deformation. Optical transmittances of the ITO-NP conductors on flexible glass substrate were enhanced to more than 91% that is higher than those on rigid glass substrate owing to decreased thickness. As well, the ITO-NP conductors on flexible glass substrate heat-treated at 500 and 600 °C showed good thermal stabilities of electrical and optical properties. In case of bending characteristics of samples heat-treated at 500 and 600 °C, the change in resistance was slight within 14%, which is smaller than those of conventional TCOs on flexible films. Based on the results, we propose that the solution-processed ITO-NP conductors are suitable for TCOs on flexible glass substrates.

  11. Increased cell survival of cells exposed to superparamagnetic iron oxide nanoparticles through biomaterial substrate-induced autophagy.

    PubMed

    Tseng, Ting-Chen; Hsieh, Fu-Yu; Hsu, Shan-Hui

    2016-04-22

    The cellular uptake of nanoparticles (NPs) can be promoted by NP surface modification but cell viability is often sacrificed. Our previous study has shown that intracellular uptake of iron oxide NPs was significantly increased for cells cultured on chitosan. However, the mechanism for having the higher cellular uptake as well as better cell survival on the chitosan surface remains unclear. In this study, we sought to clarify if the autophagic response may contribute to cell survival under excessive NP exposure conditions on chitosan. L929 fibroblasts and neural stem cells (NSCs) were challenged with different concentrations (0-300 μg ml(-1)) of superparamagnetic iron oxide NPs. The autophagic response as well as the metabolic activity of cells was evaluated. Results showed that culturing both types of cells on chitosan substrates significantly enhanced the cellular uptake of NPs. At higher NP concentrations, cells on chitosan showed a greater survival rate than those on TCPS. The expression levels of autophagy-related genes (Atg5 and Atg7 genes) and autophagy associated protein (LC3-II) on chitosan were higher than that on TCPS. The NP exposure further increased the expressions. We suggest that cells cultured on chitosan were more tolerant to NP cytotoxicity because of the increased autophagic response. Moreover, NP exposure increased the metabolic activity of cells grown on chitosan, while it decreased the metabolism of cells cultured on TCPS. In animal studies, iron oxide-labeled NSCs were injected in zebrafish embryos. Results also showed that cells grown on chitosan had better survival after transplantation than those grown on TCPS. Taken together, chitosan as a culture substrate can induce cell autophagy to increase cell survival in particular for NP-labeled cells. This will be valuable for the biomedical application of NPs in cell therapy. PMID:26815305

  12. Effects of sputtering power on properties of copper oxides thin films deposited on glass substrates

    SciTech Connect

    Ooi, P. K.; Ng, S. S.; Abdullah, M. J.

    2015-04-24

    Copper oxides are deposited by radio frequency sputtering using copper target in the mixture of argon and oxygen gasses. The structural and optical properties of the copper oxides deposited at different sputtering powers have been investigated. All the films are single phase polycrystalline. At low RF power (100 W), the film is monoclinic structure of cupric oxide (CuO). Meanwhile, the films are cubic structure of cuprous oxide (Cu2O) at higher RF power. Field emission scanning electron microscopy images show the films have different morphologies with small grain size and consist of a lot of voids. The analysis of energy dispersive X-ray spectroscopy shows that the ratio of Cu to O is increased as the RF power increased. From the ultraviolet–visible spectroscopy, the films have a broad absorption edge in the range of 300–500 nm. The band gap of the films grown at RF power of 100 W, and 120 W and above, were 1.18 eV and 2.16 eV, respectively.

  13. Fabrication and characterization of ZnO nanowires by wet oxidation of Zn thin film deposited on Teflon substrate

    NASA Astrophysics Data System (ADS)

    Farhat, O. F.; Halim, M. M.; Abdullah, M. J.; Ali, M. K. M.; Ahmed, Naser M.; Bououdina, M.

    2015-10-01

    In this study, ZnO nanowires (NWs) were successfully grown for the first time on to Teflon substrate by a wet oxidation of a Zn thin film coated by RF sputtering technique. The sputtered Zn thin film was oxidized at 100 °C for 5 h under water-vapour using a horizontal furnace. This oxidation process transformed Zn thin film into ZnO with wire-like nanostructure. XRD analysis confirms the formation of single nanocrystalline ZnO phase having a low compressive strain. FESEM observations reveal high density of ZnO NWs with diameter ranging from 34 to 52 nm and length about 2.231 μm, which are well distributed in different direction. A flexible ZnO NWs-based metal-semiconductor-metal UV photodetector was fabricated. Photo-response and sensitivity measurements under low power illumination (375 nm, 1.5 mW/cm2) showed a high sensitivity of 2050%, which can be considered a relatively fast response and baseline recovery for UV detection.

  14. Stability Comparison of Perovskite Solar Cells Based on Zinc Oxide and Titania on Polymer Substrates.

    PubMed

    Dkhissi, Yasmina; Meyer, Steffen; Chen, Dehong; Weerasinghe, Hasitha C; Spiccia, Leone; Cheng, Yi-Bing; Caruso, Rachel A

    2016-04-01

    Device scale-up and long-term stability constitute two major hurdles that the emerging perovskite solar technology will have to overcome before commercialization. Here, a comparative study was performed between ZnO and TiO2 electron-selective layers, two materials that allow the low-temperature processing of perovskite solar cells on polymer substrates. Although the use of TiO2 is well established on glass substrates, ZnO was chosen because it can be readily printed at low temperature and offers the potential for the large-scale roll-to-roll manufacturing of flexible photovoltaics at a low cost. However, a rapid degradation of CH3 NH3 PbI3 was observed if it was deposited on ZnO, therefore, the influence of the perovskite film preparation conditions on its morphology and degradation kinetics was investigated. This study showed that CH3 NH3 PbI3 could withstand a higher temperature on TiO2 than ZnO and that TiO2 -based perovskite devices were more stable than their ZnO analogues. PMID:26893225

  15. Effect of Oxidation Temperature on Physical and Electrical Properties of Sm2O3 Thin-Film Gate Oxide on Si Substrate

    NASA Astrophysics Data System (ADS)

    Goh, Kian Heng; Haseeb, A. S. M. A.; Wong, Yew Hoong

    2016-06-01

    Thermal oxidation of 150-nm sputtered pure samarium metal film on silicon substrate has been carried out in oxygen ambient at various temperatures (600°C to 900°C) for 15 min and the effect of the oxidation temperature on the structural, chemical, and electrical properties of the resulting Sm2O3 layers investigated. The crystallinity of the Sm2O3 films and the existence of an interfacial layer were evaluated by x-ray diffraction (XRD) analysis, Fourier-transform infrared (FTIR) spectroscopy, and Raman analysis. The crystallite size and microstrain of Sm2O3 were estimated by Williamson-Hall (W-H) plot analysis, with comparison of the former with the crystallite size of Sm2O3 as calculated using the Scherrer equation. High-resolution transmission electron microscopy (HRTEM) with energy-dispersive x-ray (EDX) spectroscopy analysis was carried out to investigate the cross-sectional morphology and chemical distribution of selected regions. The activation energy or growth rate of each stacked layer was calculated from Arrhenius plots. The surface roughness and topography of the Sm2O3 layers were examined by atomic force microscopy (AFM) analysis. A physical model based on semipolycrystalline nature of the interfacial layer is suggested and explained. Results supporting such a model were obtained by FTIR, XRD, Raman, EDX, and HRTEM analyses. Electrical characterization revealed that oxidation temperature at 700°C yielded the highest breakdown voltage, lowest leakage current density, and highest barrier height value.

  16. Air, aqueous and thermal stabilities of Ce3+ ions in cerium oxide nanoparticle layers with substrates.

    PubMed

    Naganuma, Tamaki; Traversa, Enrico

    2014-06-21

    Abundant oxygen vacancies coexisting with Ce(3+) ions in fluorite cerium oxide nanoparticles (CNPs) have the potential to enhance catalytic ability, but the ratio of unstable Ce(3+) ions in CNPs is typically low. Our recent work, however, demonstrated that the abundant Ce(3+) ions created in cerium oxide nanoparticle layers (CNPLs) by Ar ion irradiation were stable in air at room temperature. Ce valence states in CNPs correlate with the catalytic ability that involves redox reactions between Ce(3+) and Ce(4+) ions in given application environments (e.g. high temperature in carbon monoxide gas conversion and immersion conditions in biomedical applications). To better understand the mechanism by which Ce(3+) ions achieve stability in CNPLs, we examined (i) extra-long air-stability, (ii) thermal stability up to 500 °C, and (iii) aqueous stability of Ce(3+) ions in water, buffer solution and cell culture medium. It is noteworthy that air-stability of Ce(3+) ions in CNPLs persisted for more than 1 year. Thermal stability results showed that oxidation of Ce(3+) to Ce(4+) occurred at 350 °C in air. Highly concentrated Ce(3+) ions in ultra-thin CNPLs slowly oxidized in water within 1 day, but stability was improved in the cell culture medium. Ce(3+) stability of CNPLs immersed in the medium was associated with phosphorus adsorption on the Ce(3+) sites. This study also illuminates the potential interaction mechanisms of stable Ce(3+) ions in CNPLs. These findings could be utilized to understand catalytic mechanisms of CNPs with abundant oxygen vacancies in their application environments. PMID:24812662

  17. Development of Oxidation Resistant Coatings on GRCop-84 Substrates by Cold Spray Process

    NASA Technical Reports Server (NTRS)

    Karthikeyan, J.

    2007-01-01

    GRCop-84, a Cu-CR-Nb alloy, has been developed for rocket engine liner applications. For maximum life additional oxidation protection is required to prevent blanching. NiCrAlY was identified as a suitable coating, and efforts were initiated to develop suitable coating techniques. Cold spray is one technique under consideration. Efforts at ASB Industries to produce dense, adherent coatings are detailed. The work culminated in the production of samples for testing at NASA Glenn Research Center.

  18. Marine sediments microbes capable of electrode oxidation as a surrogate for lithotrophic insoluble substrate metabolism.

    PubMed

    Rowe, Annette R; Chellamuthu, Prithiviraj; Lam, Bonita; Okamoto, Akihiro; Nealson, Kenneth H

    2014-01-01

    Little is known about the importance and/or mechanisms of biological mineral oxidation in sediments, partially due to the difficulties associated with culturing mineral-oxidizing microbes. We demonstrate that electrochemical enrichment is a feasible approach for isolation of microbes capable of gaining electrons from insoluble minerals. To this end we constructed sediment microcosms and incubated electrodes at various controlled redox potentials. Negative current production was observed in incubations and increased as redox potential decreased (tested -50 to -400 mV vs. Ag/AgCl). Electrode-associated biomass responded to the addition of nitrate and ferric iron as terminal electron acceptors in secondary sediment-free enrichments. Elemental sulfur, elemental iron and amorphous iron sulfide enrichments derived from electrode biomass demonstrated products indicative of sulfur or iron oxidation. The microbes isolated from these enrichments belong to the genera Halomonas, Idiomarina, Marinobacter, and Pseudomonas of the Gammaproteobacteria, and Thalassospira and Thioclava from the Alphaproteobacteria. Chronoamperometry data demonstrates sustained electrode oxidation from these isolates in the absence of alternate electron sources. Cyclic voltammetry demonstrated the variability in dominant electron transfer modes or interactions with electrodes (i.e., biofilm, planktonic or mediator facilitated) and the wide range of midpoint potentials observed for each microbe (from 8 to -295 mV vs. Ag/AgCl). The diversity of extracellular electron transfer mechanisms observed in one sediment and one redox condition, illustrates the potential importance and abundance of these interactions. This approach has promise for increasing our understanding the extent and diversity of microbe mineral interactions, as well as increasing the repository of microbes available for electrochemical applications. PMID:25642220

  19. Marine sediments microbes capable of electrode oxidation as a surrogate for lithotrophic insoluble substrate metabolism

    PubMed Central

    Rowe, Annette R.; Chellamuthu, Prithiviraj; Lam, Bonita; Okamoto, Akihiro; Nealson, Kenneth H.

    2015-01-01

    Little is known about the importance and/or mechanisms of biological mineral oxidation in sediments, partially due to the difficulties associated with culturing mineral-oxidizing microbes. We demonstrate that electrochemical enrichment is a feasible approach for isolation of microbes capable of gaining electrons from insoluble minerals. To this end we constructed sediment microcosms and incubated electrodes at various controlled redox potentials. Negative current production was observed in incubations and increased as redox potential decreased (tested −50 to −400 mV vs. Ag/AgCl). Electrode-associated biomass responded to the addition of nitrate and ferric iron as terminal electron acceptors in secondary sediment-free enrichments. Elemental sulfur, elemental iron and amorphous iron sulfide enrichments derived from electrode biomass demonstrated products indicative of sulfur or iron oxidation. The microbes isolated from these enrichments belong to the genera Halomonas, Idiomarina, Marinobacter, and Pseudomonas of the Gammaproteobacteria, and Thalassospira and Thioclava from the Alphaproteobacteria. Chronoamperometry data demonstrates sustained electrode oxidation from these isolates in the absence of alternate electron sources. Cyclic voltammetry demonstrated the variability in dominant electron transfer modes or interactions with electrodes (i.e., biofilm, planktonic or mediator facilitated) and the wide range of midpoint potentials observed for each microbe (from 8 to −295 mV vs. Ag/AgCl). The diversity of extracellular electron transfer mechanisms observed in one sediment and one redox condition, illustrates the potential importance and abundance of these interactions. This approach has promise for increasing our understanding the extent and diversity of microbe mineral interactions, as well as increasing the repository of microbes available for electrochemical applications. PMID:25642220

  20. Immobilization of iron oxide nanoclusters on surface functionalized silicon substrate and their catalytic behavior to synthesize multi-walled carbon nanotubes.

    PubMed

    Adhikari, Prashanta Dhoj; Kim, Sunghwan; Lee, Sui; Park, Chong-Yun

    2013-07-01

    Multi-walled carbon nanotubes (MWCNTs) were grown using iron oxide nanoclusters (Nc) assisted by self-assembled monolayer (SAM) on substrate. The amine-terminated SAM fabricated on silicon substrate (APTMS/SI) was carried out by UV-treatment and immersed into the FeCI3/HCI aqueous solution. Then, Nc were immobilized onto oxidized SAM silicon substrate (SAMs/Si) through electrostatic interaction between cationic Nc and anionic SAMs/Si. The characterization results clearly show that the well-graphitized MWCNTs were synthesized by using functionalized silicon substrate (Nc/SAMs/Si) as a template having appropriate density of catalyst. These consequences show that SAM containing template is important to achieve the effective layer of catalyst to synthesize MWCNTs in chemical vapor deposition (CVD). PMID:23901478

  1. Epitaxial iron oxide nanocrystals with memory function grown on Si substrates

    NASA Astrophysics Data System (ADS)

    Ishibe, Takafumi; Matsui, Hideki; Watanabe, Kentaro; Takeuchi, Shotaro; Sakai, Akira; Nakamura, Yoshiaki

    2016-05-01

    High-density Fe3O4‑δ nanocrystals (NCs) were epitaxially grown on Si substrates by molecular beam epitaxy with epitaxial Ge NCs being used as nucleation sites. Scanning tunneling spectroscopy measurements showed that the surface bandgap of the as-grown Fe3O4‑δ NCs was ∼0.2 eV, consistent with that reported for Fe3O4‑δ films. Conductive atomic force microscopy measurements of the NCs revealed hysteresis in the voltage–current curves, indicating bipolar resistive switching behavior. The measurement results established the superiority of the NCs to thin conventional polycrystalline Fe3O4‑δ films/Si in terms of resistive switching characteristics. This demonstrated the possibility of developing resistance random access memory devices composed of ubiquitous Fe3O4‑δ NC materials.

  2. Synthesis, characterization, structural, and optical properties of zinc oxide nanostructures embedded in silicon based substrates

    NASA Astrophysics Data System (ADS)

    Pandey, Bimal

    Structural and optical properties of ZnO nanostructures synthesized by low energy ion implantation technique were examined. ZnO molecular ions were implanted into Si/SiO2 substrates at room temperature and then furnace annealed under different temperatures and environments. In all as-implanted samples only Zn nanostructures with varying diameters distributed into the Si/SiO2 matrices were observed. No trace of ZnO was found. The distributions of Zn nanostructures in Si/SiO2 closely matched results from Stopping and Range of Ions in Matter (SRIM) simulations. During annealing at 750 °C, Zn diffused both toward and away from the surface of the substrate and combine with oxygen to form ZnO nanostructures. At higher annealing temperatures ZnO bonding started to break down and transfer to zinc silicate (Zn2SiO4), and at 900 °C the ZnO was completely converted into Zn2SiO4. The average sizes of Zn/ZnO nanostructures depended on the ion fluence. If the fluence increased the average sizes of nanostructures also increased and vice versa. For room temperature photoluminescence (RT-PL), band-edge emission in the ultraviolet (UV) region was observed from all samples annealed at 700 °C/750 °C and were slightly blue shifted as compare to bulk ZnO. Donor-bound exciton (D,X) and acceptor-bound exciton (A,X) transitions were observed in low temperature photoluminescence (PL). The lifetime of both donor-bound excitonic emission (D, X) and acceptor-bound excitonic emission (A, X) were found to be in the picosecond (ps) range.

  3. Ceria catalyst for inert-substrate-supported tubular solid oxide fuel cells running on methane fuel

    NASA Astrophysics Data System (ADS)

    Zhao, Kai; Kim, Bok-Hee; Du, Yanhai; Xu, Qing; Ahn, Byung-Guk

    2016-05-01

    A ceria catalyst is applied to an inert-substrate supported tubular single cell for direct operation on methane fuel. The tubular single cell comprises a porous yttria-stabilized zirconia (YSZ) supporter, a Ni-Ce0.8Sm0.2O1.9 anode, a YSZ/Ce0.8Sm0.2O1.9 bi-layer electrolyte, and a La0.6Sr0.4Co0.2Fe0.8O3-δ cathode. The ceria catalyst is incorporated into the porous YSZ supporter layer by a cerium nitrate impregnation. The effects of ceria on the microstructure and electrochemical performance of the tubular single cell are investigated with respect to the number of impregnations. The optimum number of impregnations is determined to be four based on the maximum power density and polarization property of the tubular single cell in hydrogen and methane fuels. At 700 °C, the tubular single cell shows similar maximum power densities of ∼260 mW cm-2 in hydrogen and methane fuels, respectively. Moreover, the ceria catalyst significantly improves the performance stability of the cell running on methane fuel. At a current density of 350 mA cm-2, the single cell shows a low degradation rate of 2.5 mV h-1 during the 13 h test in methane fuel. These results suggest the feasibility of applying the ceria catalyst to the inert-substrate supported tubular single cell for direct operation on methane fuel.

  4. Surface studies on aluminized and thermally oxidized superalloy 690 substrates interacted with simulated nuclear waste and sodium borosilicate melt

    NASA Astrophysics Data System (ADS)

    Yusufali, C.; Kshirsagar, R. J.; Mishra, R. K.; Kaushik, C. P.; Sengupta, P.; Dutta, R. S.; Dey, G. K.

    2014-04-01

    Aluminized and thermally oxidized Ni-Cr-Fe based superalloy 690 substrates with Al2O3 layer on top have been exposed in nitrate based environment (simulated high level nuclear liquid waste) at 373 K for 216 hours and sodium borosilicate melt at 1248 K for 192 hours. The surfaces of exposed samples have been characterized by using Electron probe micro-analyzer (EPMA). Elemental X-ray mapping on coated specimen that exposed in simulated nuclear waste solution revealed that the surface is enriched with Ni, Cr and Al. X-ray mapping on surface of the specimen that interacted with sodium borosilicate melt indicated that the surface is composed of Al, Fe, Ni and Cr.

  5. Flexible nickel-doped zinc oxide thin-film transistors fabricated on plastic substrates at low temperature

    NASA Astrophysics Data System (ADS)

    Huang, Lingling; Han, Dedong; Chen, Zhuofa; Cong, Yingying; Wu, Jing; Zhao, Nannan; Dong, Junchen; Zhao, Feilong; Liu, Lifeng; Zhang, Shengdong; Zhang, Xing; Wang, Yi

    2015-04-01

    High-performance nickel (Ni)-doped zinc oxide thin-film transistors (NZO TFTs) have been successfully fabricated on transparent flexible plastic substrates at a low temperature. The effect of different oxygen partial pressures during channel deposition on the electrical properties of NZO TFTs was studied to improve the device performance. We found that the oxygen partial pressure during channel deposition has a significant influence on the performance of NZO TFTs. Finally, it was demonstrated that a NZO film with 100% Ar sputtering gas during channel deposition exhibited the best electrical properties, with a drain current on/off ratio of 108, a positive threshold voltage of 2.59 V, a subthreshold swing of 233 mV/decade, and a saturation mobility of 118.9 cm2·V-1·s-1. The results show that Ni-doped ZnO is a promising candidate for flexible fully transparent displays.

  6. Surface studies on aluminized and thermally oxidized superalloy 690 substrates interacted with simulated nuclear waste and sodium borosilicate melt

    SciTech Connect

    Yusufali, C. Sengupta, P.; Dutta, R. S.; Dey, G. K.; Kshirsagar, R. J.; Mishra, R. K.; Kaushik, C. P.

    2014-04-24

    Aluminized and thermally oxidized Ni-Cr-Fe based superalloy 690 substrates with Al{sub 2}O{sub 3} layer on top have been exposed in nitrate based environment (simulated high level nuclear liquid waste) at 373 K for 216 hours and sodium borosilicate melt at 1248 K for 192 hours. The surfaces of exposed samples have been characterized by using Electron probe micro-analyzer (EPMA). Elemental X-ray mapping on coated specimen that exposed in simulated nuclear waste solution revealed that the surface is enriched with Ni, Cr and Al. X-ray mapping on surface of the specimen that interacted with sodium borosilicate melt indicated that the surface is composed of Al, Fe, Ni and Cr.

  7. Effect of time and of precursor molecule on the deposition of hydrophobic nanolayers on ethyelene tetrafluoroethylene-silicon oxide substrates

    NASA Astrophysics Data System (ADS)

    Rossi, Gabriella; Castellano, Piera; Incarnato, Loredana

    2016-01-01

    A method was developed for generating transparent and hydrophobic nanolayers chemisorbed onto flexible substrates of ethylene tetrafluoroethylene-silicon oxide (ETFE-SiOx). In particular, the effect of the deposition time and of the precursor molecule on the nanocoating process was analyzed with the aim of pursuing an optimization of the above method in an industrial application perspective. It was found that precursor molecule of triethoxysilane allowed to obtain better hydrophobic properties on the SiOx surface in shorter times compared to trichlorosilane, reaching the 92 % of final contact angle (CA) value of 106° after only 1 h of deposition. The optical properties and surface morphology were also assessed in function of time, revealing that an initial transparency reduction is followed by a subsequent transmittance increase during the self assembly of fluoroalkylsilanes on the SiOx surface, coherently with the surface roughness analysis data. Encouraging results were also obtained in terms of oleophobic properties improvement of the nanocoated surfaces.

  8. Magneto-transport properties of oriented Mn{sub 2}CoAl films sputtered on thermally oxidized Si substrates

    SciTech Connect

    Xu, G. Z.; Du, Y.; Zhang, X. M.; Liu, E. K.; Wang, W. H. Wu, G. H.; Zhang, H. G.

    2014-06-16

    Spin gapless semiconductors are interesting family of materials by embracing both magnetism and semiconducting due to their unique band structure. Its potential application in future spintronics requires realization in thin film form. In this Letter, we report fabrication and transport properties of spin gapless Mn{sub 2}CoAl films prepared on thermally oxidized Si substrates by magnetron sputtering deposition. The films deposited at 673 K are well oriented to (001) direction and display a uniform-crystalline surface. Magnetotransport measurements on the oriented films reveal a semiconducting-like resistivity, small anomalous Hall conductivity, and linear magnetoresistance representative of the transport signatures of spin gapless semiconductors. The magnetic properties of the films have also been investigated and compared to that of bulk Mn{sub 2}CoAl, showing small discrepancy induced by the composition deviation.

  9. Enhanced field emission properties from well-aligned zinc oxide nanoneedles grown on the Au/Ti/n-Si substrate

    SciTech Connect

    Park, Chan Jun; Choi, Duck-Kyun; Yoo, Jinkyoung; Yi, Gyu-Chul; Lee, Cheol Jin

    2007-02-19

    The authors investigated the field emission from vertically well-aligned zinc oxide (ZnO) nanoneedles grown on the Au/Ti/n-Si (100) substrate using metal organic chemical vapor deposition. The turn-on field of ZnO nanoneedles was about 0.85 V/{mu}m at the current density of 0.1 {mu}A/cm{sup 2}, and the emission current density of 1 mA/cm{sup 2} was achieved at the applied electric field of 5.0 V/{mu}m. The low turn-on field of the ZnO nanoneedles was attributed to very sharp tip morphology, and the high emission current density was mainly caused by the formation of the stable Ohmic contact between the ZnO nanoneedles and Au film.

  10. Formation of oxides and their role in the growth of Ag nanoplates on GaAs substrates.

    SciTech Connect

    Sun, Y.; Gosztola, D.; Lei, C.; Haasch, R.; Center for Nanoscale Materials; Univ. of Illinois

    2008-10-21

    Simple galvanic reactions between highly doped n-type GaAs wafers and a pure aqueous solution of AgNO3 at room temperature provide an easy and efficient protocol to directly deposit uniform Ag nanoplates with tunable dimensions on the GaAs substrates. The anisotropic growth of the Ag nanoplates in the absence of surfactant molecules might be partially ascribed to the codeposition of oxides of gallium and arsenic, which are revealed by extensive data from electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy, during the growth of the Ag nanoplates. The electron microscopic characterization shows that each Ag nanoplate has a 'necked' geometry, that is, it pins on the GaAs lattices through only a tiny neck (with sizes of <10 nm). In addition, the as-grown Ag nanoplates exhibit strong enhancement toward Raman scattering of materials on (or around) their surfaces.