WorldWideScience

Sample records for buffered metal substrates

  1. ZnO buffer layer for metal films on silicon substrates

    Science.gov (United States)

    Ihlefeld, Jon

    2014-09-16

    Dramatic improvements in metallization integrity and electroceramic thin film performance can be achieved by the use of the ZnO buffer layer to minimize interfacial energy between metallization and adhesion layers. In particular, the invention provides a substrate metallization method utilizing a ZnO adhesion layer that has a high work of adhesion, which in turn enables processing under thermal budgets typically reserved for more exotic ceramic, single-crystal, or metal foil substrates. Embodiments of the present invention can be used in a broad range of applications beyond ferroelectric capacitors, including microelectromechanical systems, micro-printed heaters and sensors, and electrochemical energy storage, where integrity of metallized silicon to high temperatures is necessary.

  2. Growth and BZO-doping of the nanostructured YBCO thin films on buffered metal substrates

    DEFF Research Database (Denmark)

    Huhtinen, H.; Irjala, M.; Paturi, P.

    2010-01-01

    and moreover out-of-plane long range lattice ordering is greatly reduced. Magnetic measurements demonstrate that jc in films grown on NiW is higher in high magnetic fields and low temperatures. This effect is connected to the amount of pinning centres observed in films on metal substrates which are effective...

  3. Development and application of a green-chemistry solution deposition technique for buffer layer coating on cube-textured metal substrates in view of further deposition of rare-earth based superconductors

    DEFF Research Database (Denmark)

    Pallewatta, Pallewatta G A P

    and hazardous chemicals such as 2-methoxyethanol, and trifluroacetic acid (TFA). Therefore, in our research the main focus was on the development of SrTiO3 single buffer layers based on environmentally safe chemicals, to reach the engineering requirements for continuous coating of long substrate tapes. A new...... precursor solution for SrTiO3 buffer layers has been successfully developed with the reagents of strontium acetate, acetic acid, titanium isopropoxide, 1-methoxy-2-propanol and 2,4-pentanedione. Using this precursor with dip-coating, high cube-textured SrTiO3 mono-coatings on Cu-33at.%Ni tapes were...... which consist of YBCO superconducting coatings on cube-textured Ni based alloy tapes.  Before the epitaxial deposition this superconducting layer, a buffer layer is applied on the metal substrate as a diffusion barrier which is also required to transfer the strong texture of the underlying substrate...

  4. Conductive and robust nitride buffer layers on biaxially textured substrates

    Science.gov (United States)

    Sankar, Sambasivan [Chicago, IL; Goyal, Amit [Knoxville, TN; Barnett, Scott A [Evanston, IL; Kim, Ilwon [Skokie, IL; Kroeger, Donald M [Knoxville, TN

    2009-03-31

    The present invention relates to epitaxial, electrically conducting and mechanically robust, cubic nitride buffer layers deposited epitaxially on biaxially textured substrates such as metals and alloys. The invention comprises of a biaxially textured substrate with epitaxial layers of nitrides. The invention also discloses a method to form such epitaxial layers using a high rate deposition method as well as without the use of forming gases. The invention further comprises epitaxial layers of oxides on the biaxially textured nitride layer. In some embodiments the article further comprises electromagnetic devices which may have superconducting properties.

  5. Effect of maleic anhydride-aniline derivative buffer layer on the properties of flexible substrate heterostructures: Indium tin oxide/nucleic acid base/metal

    Energy Technology Data Exchange (ETDEWEB)

    Stanculescu, A., E-mail: sanca@infim.ro [National Institute of Materials Physics, 105 bis Atomistilor Street, P.O. Box MG-7, 077125, Bucharest-Magurele (Romania); Socol, M. [National Institute of Materials Physics, 105 bis Atomistilor Street, P.O. Box MG-7, 077125, Bucharest-Magurele (Romania); Socol, G.; Mihailescu, I.N. [National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG-36, 077125, Bucharest-Magurele (Romania); Girtan, M. [Laboratoire de Photonique d' Angers, Universite d' Angers, 2, Bd. Lavoisier, 49045, Angers (France); Preda, N. [National Institute of Materials Physics, 105 bis Atomistilor Street, P.O. Box MG-7, 077125, Bucharest-Magurele (Romania); Albu, A.-M. [Department of Polymer Science, University ' Politehnica' of Bucharest, Bucharest (Romania); Stanculescu, F. [University of Bucharest, Faculty of Physics, Str. Atomistilor nr.405, P.O. Box MG-11, Bucharest-Magurele, 077125 (Romania)

    2011-12-01

    This paper presents some investigations on the properties of guanine (G) and cytosine (C) based heterostructures deposited on flexible substrates. The effects of two types of maleic anhydride-aniline derivatives (maleic anhydride-cyano aniline or maleic anhydride-2,4 dinitroaniline) buffer layer, deposited between indium tin oxide and (G) or (C) layer, on the optical and electrical properties of the heterostructures have been identified. The heterostructures containing a film of maleic anhydride-2,4 dinitroaniline have shown a good transparency and low photoluminescence in visible range. This buffer layer has determined an increase in the conductance only in the heterostructures based on (G) and (C) deposited on biaxially-oriented polyethylene terephthalate substrate.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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.

  8. Strontium Titanate Buffer Layers on Cu/33%Ni Substrates using a Novel Solution Chemistry

    DEFF Research Database (Denmark)

    Pallewatta, Pallewatta G A P; Yue, Zhao; Hui, Tian

    2013-01-01

    SrTiO3 is a widely studied perovskite material due to its advantages as a buffer template which can be simply applied between a metal substrate tape and a superconducting layer in 2G high temperature superconducting (HTS) tapes. In this study, heteroepitaxial SrTiO3 thin films were deposited on t...

  9. MgO buffer layers on rolled nickel or copper as superconductor substrates

    Science.gov (United States)

    Paranthaman, Mariappan; Goyal, Amit; Kroeger, Donald M.; List, III, Frederic A.

    2001-01-01

    Buffer layer architectures are epitaxially deposited on biaxially-textured rolled-Ni and/or Cu substrates for high current conductors, and more particularly buffer layer architectures such as MgO/Ag/Pt/Ni, MgO/Ag/Pd/Ni, MgO/Ag/Ni, MgO/Ag/Pd/Cu, MgO/Ag/Pt/Cu, and MgO/Ag/Cu. Techniques used to deposit these buffer layers include electron beam evaporation, thermal evaporation, rf magnetron sputtering, pulsed laser deposition, metal-organic chemical vapor deposition (MOCVD), combustion CVD, and spray pyrolysis.

  10. Substrate-induced magnetism in epitaxial graphene buffer layers.

    Science.gov (United States)

    Ramasubramaniam, A; Medhekar, N V; Shenoy, V B

    2009-07-08

    Magnetism in graphene is of fundamental as well as technological interest, with potential applications in molecular magnets and spintronic devices. While defects and/or adsorbates in freestanding graphene nanoribbons and graphene sheets have been shown to cause itinerant magnetism, controlling the density and distribution of defects and adsorbates is in general difficult. We show from first principles calculations that graphene buffer layers on SiC(0001) can also show intrinsic magnetism. The formation of graphene-substrate chemical bonds disrupts the graphene pi-bonds and causes localization of graphene states near the Fermi level. Exchange interactions between these states lead to itinerant magnetism in the graphene buffer layer. We demonstrate the occurrence of magnetism in graphene buffer layers on both bulk-terminated as well as more realistic adatom-terminated SiC(0001) surfaces. Our calculations show that adatom density has a profound effect on the spin distribution in the graphene buffer layer, thereby providing a means of engineering magnetism in epitaxial graphene.

  11. Carbon Nanotube Patterning on a Metal Substrate

    Science.gov (United States)

    Nguyen, Cattien V. (Inventor)

    2016-01-01

    A CNT electron source, a method of manufacturing a CNT electron source, and a solar cell utilizing a CNT patterned sculptured substrate are disclosed. Embodiments utilize a metal substrate which enables CNTs to be grown directly from the substrate. An inhibitor may be applied to the metal substrate to inhibit growth of CNTs from the metal substrate. The inhibitor may be precisely applied to the metal substrate in any pattern, thereby enabling the positioning of the CNT groupings to be more precisely controlled. The surface roughness of the metal substrate may be varied to control the density of the CNTs within each CNT grouping. Further, an absorber layer and an acceptor layer may be applied to the CNT electron source to form a solar cell, where a voltage potential may be generated between the acceptor layer and the metal substrate in response to sunlight exposure.

  12. Metal oxide nanorod arrays on monolithic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Pu-Xian; Guo, Yanbing; Ren, Zheng

    2018-01-02

    A metal oxide nanorod array structure according to embodiments disclosed herein includes a monolithic substrate having a surface and multiple channels, an interface layer bonded to the surface of the substrate, and a metal oxide nanorod array coupled to the substrate surface via the interface layer. The metal oxide can include ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide. The substrate can include a glass substrate, a plastic substrate, a silicon substrate, a ceramic monolith, and a stainless steel monolith. The ceramic can include cordierite, alumina, tin oxide, and titania. The nanorod array structure can include a perovskite shell, such as a lanthanum-based transition metal oxide, or a metal oxide shell, such as ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide, or a coating of metal particles, such as platinum, gold, palladium, rhodium, and ruthenium, over each metal oxide nanorod. Structures can be bonded to the surface of a substrate and resist erosion if exposed to high velocity flow rates.

  13. Pulsed laser deposition of YBCO films on ISD MgO buffered metal tapes

    CERN Document Server

    Ma, B; Koritala, R E; Fisher, B L; Markowitz, A R; Erck, R A; Baurceanu, R; Dorris, S E; Miller, D J; Balachandran, U

    2003-01-01

    Biaxially textured magnesium oxide (MgO) films deposited by inclined-substrate deposition (ISD) are desirable for rapid production of high-quality template layers for YBCO-coated conductors. High-quality YBCO films were grown on ISD MgO buffered metallic substrates by pulsed laser deposition (PLD). Columnar grains with a roof-tile surface structure were observed in the ISD MgO films. X-ray pole figure analysis revealed that the (002) planes of the ISD MgO films are tilted at an angle from the substrate normal. A small full-width at half maximum (FWHM) of approx 9deg was observed in the phi-scan for ISD MgO films deposited at an inclination angle of 55deg . In-plane texture in the ISD MgO films developed in the first approx 0.5 mu m from the substrate surface, and then stabilized with further increases in film thickness. Yttria-stabilized zirconia and ceria buffer layers were deposited on the ISD MgO grown on metallic substrates prior to the deposition of YBCO by PLD. YBCO films with the c-axis parallel to the...

  14. Methods of producing free-standing semiconductors using sacrificial buffer layers and recyclable substrates

    Science.gov (United States)

    Ptak, Aaron Joseph; Lin, Yong; Norman, Andrew; Alberi, Kirstin

    2015-05-26

    A method of producing semiconductor materials and devices that incorporate the semiconductor materials are provided. In particular, a method is provided of producing a semiconductor material, such as a III-V semiconductor, on a spinel substrate using a sacrificial buffer layer, and devices such as photovoltaic cells that incorporate the semiconductor materials. The sacrificial buffer material and semiconductor materials may be deposited using lattice-matching epitaxy or coincident site lattice-matching epitaxy, resulting in a close degree of lattice matching between the substrate material and deposited material for a wide variety of material compositions. The sacrificial buffer layer may be dissolved using an epitaxial liftoff technique in order to separate the semiconductor device from the spinel substrate, and the spinel substrate may be reused in the subsequent fabrication of other semiconductor devices. The low-defect density semiconductor materials produced using this method result in the enhanced performance of the semiconductor devices that incorporate the semiconductor materials.

  15. Metallic coatings on silicon substrates, and methods of forming metallic coatings on silicon substrates

    Science.gov (United States)

    Branagan, Daniel J [Idaho Falls, ID; Hyde, Timothy A [Idaho Falls, ID; Fincke, James R [Los Alamos, NM

    2008-03-11

    The invention includes methods of forming a metallic coating on a substrate which contains silicon. A metallic glass layer is formed over a silicon surface of the substrate. The invention includes methods of protecting a silicon substrate. The substrate is provided within a deposition chamber along with a deposition target. Material from the deposition target is deposited over at least a portion of the silicon substrate to form a protective layer or structure which contains metallic glass. The metallic glass comprises iron and one or more of B, Si, P and C. The invention includes structures which have a substrate containing silicon and a metallic layer over the substrate. The metallic layer contains less than or equal to about 2 weight % carbon and has a hardness of at least 9.2 GPa. The metallic layer can have an amorphous microstructure or can be devitrified to have a nanocrystalline microstructure.

  16. Microstructure evolution of GaN buffer layer on MgAl 2O 4 substrate

    Science.gov (United States)

    Yang, H.-F.; Han, P.-D.; Cheng, L.-S.; Zhang, Z.; Duan, S.-K.; Teng, X.-G.

    1998-10-01

    Microstructure of GaN buffer layer grown on (1 1 1)MgAl 2O 4 substrate by metalorganic vapor phase epitaxy (MOVPE) was studied by transmission electron microscopy (TEM). It has been observed that the early deposition of GaN buffer layer on the substrate at a relatively low temperature formed a continual island-sublayer (5 nm thick) with hexagonal crystallographic structure, and the subsequent GaN buffer deposition led to crystal columns which are composed of nano-crystal slices with mixed cubic and hexagonal phases. After high-temperature annealing, the crystallinity of nano-crystal slices and island-sublayer in the buffer layer have been improved. The formation of threading dislocations in the GaN film is attributed not only to the lattice mismatch of GaN/MgAl 2O 4 interface, but also to the stacking mismatches at the crystal column boundaries.

  17. Preventing phase separation in MOCVD-grown InAlAs compositionally graded buffer on silicon substrate using InGaAs interlayers

    Science.gov (United States)

    Kohen, David; Nguyen, Xuan Sang; Made, Riko I.; Heidelberger, Christopher; Lee, Kwang Hong; Lee, Kenneth Eng Kian; Fitzgerald, Eugene A.

    2017-11-01

    Compositionally graded InAlAs buffers grown by metal-organic chemical vapor deposition are impaired by phase separation occurring at In content higher than 35%. Phase separation results in rough epilayers with poor crystalline material quality. By introducing low temperature grown InGaAs interlayers in the compositionally graded InAlAs buffer, the surface roughness decreases, allowing a grading of up to In0.60Al0.40As without any phase separation occurring. This composite buffer is applied to fabricate a 200 mm diameter InP-on-Si virtual substrate with a threading dislocation density around 1 × 108 cm-2.

  18. Coincident site lattice-matched growth of semiconductors on substrates using compliant buffer layers

    Science.gov (United States)

    Norman, Andrew

    2016-08-23

    A method of producing semiconductor materials and devices that incorporate the semiconductor materials are provided. In particular, a method is provided of producing a semiconductor material, such as a III-V semiconductor, on a silicon substrate using a compliant buffer layer, and devices such as photovoltaic cells that incorporate the semiconductor materials. The compliant buffer material and semiconductor materials may be deposited using coincident site lattice-matching epitaxy, resulting in a close degree of lattice matching between the substrate material and deposited material for a wide variety of material compositions. The coincident site lattice matching epitaxial process, as well as the use of a ductile buffer material, reduce the internal stresses and associated crystal defects within the deposited semiconductor materials fabricated using the disclosed method. As a result, the semiconductor devices provided herein possess enhanced performance characteristics due to a relatively low density of crystal defects.

  19. Doped LZO buffer layers for laminated conductors

    Science.gov (United States)

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

    2010-03-23

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

  20. Effects of grazing management and buffer strips on metal runoff from pastures fertilized with poultry litter

    Science.gov (United States)

    Metal runoff from fields fertilized with poultry litter may pose a threat to aquatic systems. Buffer strips have been added to fields to reduce nutrients and solids runoff. However, scant information exists on the effects of buffer strips combined with grazing management strategies on metal runoff f...

  1. Transport losses in single and assembled coated conductors with textured-metal substrate with reduced magnetism

    Energy Technology Data Exchange (ETDEWEB)

    Amemiya, N. [Faculty of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501 (Japan)], E-mail: amemiya@kuee.kyoto-u.ac.jp; Jiang, Z.; Li, Z.; Nakahata, M. [Faculty of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501 (Japan); Kato, T.; Ueyama, M. [Sumitomo Electric Ind., Ltd., Electric Power and Energy Research Laboratories, 1-1-3, Shimaya, Konohana, Osaka 554-0024 (Japan); Kashima, N.; Nagaya, S. [Chubu Electric Power Co., Inc., 20-1 Kita-Sekiyama, Ohdaka, Midori, Nagoya 459-8522 (Japan); Shiohara, S. [Superconductivity Research Laboratory, ISTEC, 1-10-13 Shinonome, Koto, Tokyo 136-0062 (Japan)

    2008-09-15

    Transport losses in a coated conductor with a textured-metal substrate with reduced magnetism were studied experimentally. The substrate is with a clad structure, and HoBCO superconductor layer is deposited on the substrate with buffer layers. The measured transport loss of a sample whose critical current is 126.0 A falls between Norris's strip value and Norris's ellipse value. The increase in the measured transport loss from Norris's strip value can be attributed to its non-uniform lateral J{sub c} distribution. The same buffered clad tape was placed under an IBAD-MOCVD coated conductor with a non-magnetic substrate, and its transport loss was measured. The comparison between the measured transport loss of this sample and that of the identical IBAD-MOCVD coated conductor without the buffered clad tape indicates that the increase in the transport loss due to this buffered clad tape is small. The transport losses of hexagonal assemblies of IBAD-MOCVD coated conductors, whose structure simulates that of superconducting power transmission cables, were also measured where the buffered clad tapes were under-lied or over-lied on the coated conductors. The increase in the transport loss of hexagonal assemblies of coated conductors due to the buffered clad tapes is at an allowable level.

  2. Hydrogen production in microbial reverse-electrodialysis electrolysis cells using a substrate without buffer solution.

    Science.gov (United States)

    Song, Young-Hyun; Hidayat, Syarif; Kim, Han-Ki; Park, Joo-Yang

    2016-06-01

    The aim of this work was to use substrate without buffer solution in a microbial reverse-electrodialysis electrolysis cell (MREC) for hydrogen production under continuous flow condition (10 cell pairs of RED stacks, HRT=5, 7.5, and 15h). Decreasing in the HRT (increasing in the organic matter) made cell current stable and increased. Hydrogen gas was produced at a rate of 0.61m(3)-H2/m(3)-Van/d in H-MREC, with a COD removal efficiency of 81% (1.55g/L/d) and a Coulombic efficiency of 41%. This MREC system without buffer solution could successfully produce hydrogen gas at a consistent rate. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Tuning of large piezoelectric response in nanosheet-buffered lead zirconate titanate films on glass substrates.

    Science.gov (United States)

    Chopra, Anuj; Bayraktar, Muharrem; Nijland, Maarten; Ten Elshof, Johan E; Bijkerk, Fred; Rijnders, Guus

    2017-03-21

    Renewed interest has been witnessed in utilizing the piezoelectric response of PbZr 0.52 Ti 0.48 O 3 (PZT) films on glass substrates for applications such as adaptive optics. Accordingly, new methodologies are being explored to grow well-oriented PZT thin films to harvest a large piezoelectric response. However, thin film piezoelectric response is significantly reduced compared to intrinsic response due to substrate induced clamping, even when films are well-oriented. Here, a novel method is presented to grow preferentially (100)-oriented PZT films on glass substrates by utilizing crystalline nanosheets as seed layers. Furthermore, increasing the repetition frequency up to 20 Hz during pulsed laser deposition helps to tune the film microstructure to hierarchically ordered columns that leads to reduced clamping and enhanced piezoelectric response evidenced by transmission electron microscopy and analytical calculations. A large piezoelectric coefficient of 250 pm/V is observed in optimally tuned structure which is more than two times the highest reported piezoelectric response on glass. To confirm that the clamping compromises the piezoelectric response, denser films are deposited using a lower repetition frequency and a BiFeO 3 buffer layer resulting in significantly reduced piezoelectric responses. This paper demonstrates a novel method for PZT integration on glass substrates without compromising the large piezoelectric response.

  4. Metal plating removal from insulator substrate using pulsed arc discharge

    Science.gov (United States)

    Imasaka, K.; Gnapowski, S.; Akiyama, H.

    2014-06-01

    Removal technique of metal materials from a metal plating insulator substrate using a pulsed arc discharge was proposed and its fundamental characteristics were investigated. The metal plating substrate with three metal-layers structure (cupper, nickel and gold layers) is used as the sample substrate. Repetitive pulsed arc discharge plasma is generated using three types of electrode systems. Effects of the electrode systems on the metal plating removal from the insulator substrate were investigated. The metal plating was removed by the pulsed arc discharge between the electrode and substrate surface. A part of the gold layer, which is the topmost metal layer on the insulator substrate is vaporized and removed by the repetitive pulsed arc discharges.

  5. Effect of Cu buffer layer on magnetic anisotropy of cobalt thin films deposited on MgO(001 substrate

    Directory of Open Access Journals (Sweden)

    Syed Sheraz Ahmad

    2016-11-01

    Full Text Available Cobalt thin films with 5 nm thickness were prepared on single-crystal MgO (001 substrates with different thickness Cu buffer (0 nm, 5 nm, 10 nm, 20 nm. The structure, magnetic properties and transport behaviors were investigated by employing low-energy-electron-diffraction (LEED, magneto-optical Kerr effect (MOKE and anisotropic magnetoresistance (AMR. By comparing the magnetic properties of the sample as-deposited (without Cu buffer layer one with those having the buffer Cu, we found that the magnetic anisotropy was extremely affected by the Cu buffer layer. The magnetic anisotropy of the as-deposited, without buffer layer, sample shows the uniaxial magnetic anisotropy (UMA. We found that the symmetry of the magnetic anisotropy is changed from UMA to four-fold when the thickness of the Cu buffer layer reaches to 20 nm. Meanwhile, the coercivity increased from 49 Oe (without buffer layer to 300 Oe (with 20 nm Cu buffer, in the easy axis direction, as the thickness of the buffer layer increases. Moreover, the magnitudes of various magnetic anisotropy constants were determined from torque curves on the basis of AMR results. These results support the phenomenon shown in the MOKE.

  6. Effect of Cu buffer layer on magnetic anisotropy of cobalt thin films deposited on MgO(001) substrate

    Science.gov (United States)

    Ahmad, Syed Sheraz; He, Wei; Zhang, Yong-Sheng; Tang, Jin; Gul, Qeemat; Zhang, Xiang-Qun; Cheng, Zhao-Hua

    2016-11-01

    Cobalt thin films with 5 nm thickness were prepared on single-crystal MgO (001) substrates with different thickness Cu buffer (0 nm, 5 nm, 10 nm, 20 nm). The structure, magnetic properties and transport behaviors were investigated by employing low-energy-electron-diffraction (LEED), magneto-optical Kerr effect (MOKE) and anisotropic magnetoresistance (AMR). By comparing the magnetic properties of the sample as-deposited (without Cu buffer layer) one with those having the buffer Cu, we found that the magnetic anisotropy was extremely affected by the Cu buffer layer. The magnetic anisotropy of the as-deposited, without buffer layer, sample shows the uniaxial magnetic anisotropy (UMA). We found that the symmetry of the magnetic anisotropy is changed from UMA to four-fold when the thickness of the Cu buffer layer reaches to 20 nm. Meanwhile, the coercivity increased from 49 Oe (without buffer layer) to 300 Oe (with 20 nm Cu buffer), in the easy axis direction, as the thickness of the buffer layer increases. Moreover, the magnitudes of various magnetic anisotropy constants were determined from torque curves on the basis of AMR results. These results support the phenomenon shown in the MOKE.

  7. THz metal mesh filters on electrically thick fused silica substrates

    OpenAIRE

    Otter, WJ; F. Hu; Hazell, JF; Lucyszyn, S

    2014-01-01

    ? 2014 IEEE.This paper shows simulated and measured results of ultra-low cost metal mesh filters on electrically thick substrates for millimeter-wave and THz bands. It provides a broad overview of metal mesh filters currently available and suggest why it is worth moving to an electrically thick substrate for ultra-low cost applications. We demonstrate scalable traditional metal mesh filters on 525 ?m thick fused silica substrates. In addition, trapped-mode excitation is exploited to improve o...

  8. Does the Dirac Cone Exist in Silicene on Metal Substrates?

    Science.gov (United States)

    Quhe, Ruge; Yuan, Yakun; Zheng, Jiaxin; Wang, Yangyang; Ni, Zeyuan; Shi, Junjie; Yu, Dapeng; Yang, Jinbo; Lu, Jing

    2014-01-01

    Absence of the Dirac cone due to a strong band hybridization is revealed to be a common feature for epitaxial silicene on metal substrates according to our first-principles calculations for silicene on Ir, Cu, Mg, Au, Pt, Al, and Ag substrates. The destroyed Dirac cone of silicene, however, can be effectively restored with linear or parabolic dispersion by intercalating alkali metal atoms between silicene and the metal substrates, offering an opportunity to study the intriguing properties of silicene without further transfer of silicene from the metal substrates. PMID:24969493

  9. Low-temperature solution-processed metal oxide buffer layers fulfilling large area production requirements

    Science.gov (United States)

    Stubhan, T.; Litzov, I.; Li, Ning; Wang, H. Q.; Krantz, J.; Machui, F.; Steidl, M.; Oh, H.; Matt, G. J.; Brabec, C. J.

    2012-09-01

    This paper is a review of our previous work on the field of low temperature, solution processed metal oxide buffer layers published in various journals. Our work focuses on zinc oxide (ZnO) and aluminum-doped zinc oxide (AZO) as n-type and molybdenum oxide (MoO3) as p-type solution processed buffer layer. In addition to that, we investigate the surface modification of AZO using phosphonic acid-anchored aliphatic and fullerene self assembled monolayers (SAMs).

  10. Carbon Nanofiber layers on Metal and Carbon Substrates

    NARCIS (Netherlands)

    Pacheco Benito, Sergio

    2011-01-01

    This thesis describes the preparation of CNF layers on flat and porous substrates and their application as catalyst supports for chemical and electrochemical gas‐liquidsolid (G‐L‐S) catalytic reactions. Metal nanoparticles growing CNFs on flat metal substrates at 600°C are easily formed from NiO, in

  11. All Metal Organic Deposited High-Tc Superconducting Transition Edge Bolometer on Yttria-Stabilized Zirconia Substrate

    DEFF Research Database (Denmark)

    Mohajeri, Roya; Opata, Yuri Aparecido; Wulff, Anders Christian

    2016-01-01

    We report on the results of a YBa2Cu3O7−x (YBCO) superconductive transition edge bolometer (TEB) fabricated on a Ce0.9La0.1O2−7 (CLO) buffered single crystalline yttria-stabilized zirconia (YSZ) substrate. Metal organic deposition was used for the fabrication of both the YBCO thin film as well...

  12. Effects of Si doping on the strain relaxation of metamorphic (Al)GaInP buffers grown on GaAs substrates

    Energy Technology Data Exchange (ETDEWEB)

    Li, K.L. [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123, People’ s Republic of China (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Dong, J.R., E-mail: jrdong2007@sinano.ac.cn [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123, People’ s Republic of China (China); Sun, Y.R.; Zeng, X.L. [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123, People’ s Republic of China (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhao, Y.M.; Yu, S.Z.; Zhao, C.Y.; Yang, H. [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123, People’ s Republic of China (China)

    2014-01-01

    We investigate the effects of Si doping on the strain relaxation of the compositionally step-graded (Al)GaInP buffers grown by metal-organic chemical vapor deposition on (0 0 1) GaAs substrates with different miscuts toward (1 1 1)A. It is found that in the 2° samples, high Si doping can reduce both the α and β dislocation densities by delaying and suppressing the formation of phase separation in the buffer. In contrast, in the 7° samples, Si dopants deteriorate the buffer quality through increasing the dislocation density accompanying with the tilt reduction along the [1 1 0] direction, and a striking feature, bunches of β dislocations away from the interfaces, is observed in the [1 1 0] cross-sectional transmission electron microscopy images. A cross-slip mechanism closely associated with the pinning effect of Si on α dislocation motion is proposed to explain the multiplication of β dislocations. These results indicate that selecting a moderate Si doping density and substrate miscut are critical for the design and fabrication of metamorphic optoelectronic devices.

  13. Does the Dirac cone of germanene exist on metal substrates?

    Science.gov (United States)

    Wang, Yangyang; Li, Jingzhen; Xiong, Junhua; Pan, Yuanyuan; Ye, Meng; Guo, Ying; Zhang, Han; Quhe, Ruge; Lu, Jing

    2016-07-28

    Germanene, a germanium analogue of graphene and silicene, has been synthesized on metal substrates. It is predicted that the intrinsic germanene has a Dirac cone in its band structure, just like graphene and silicene. Using first-principles calculations, we investigate the geometrical structures and electronic properties of germanene on the Ag, Au, Cu, Al, Pt and Ir substrates. The Dirac cone of germanene is destroyed on the Al, Pt and Ir substrates but preserved on the Ag and Au substrates with a slight band hybridization. The upper part of the Dirac cone is destroyed for germanene on the Cu substrate while the lower part remains preserved. By contrast, the Dirac cone is always destroyed for silicene on these metal substrates because of a strong band hybridization. Our study suggests that it is possible to extract the intrinsic properties of germanene on the Ag and Au substrates although it appears impossible for silicene on these two substrates.

  14. System and process for aluminization of metal-containing substrates

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Yeong-Shyung; Stevenson, Jeffry W.

    2017-12-12

    A system and method are detailed for aluminizing surfaces of metallic substrates, parts, and components with a protective alumina layer in-situ. Aluminum (Al) foil sandwiched between the metallic components and a refractory material when heated in an oxidizing gas under a compression load at a selected temperature forms the protective alumina coating on the surface of the metallic components. The alumina coating minimizes evaporation of volatile metals from the metallic substrates, parts, and components in assembled devices that can degrade performance during operation at high temperature.

  15. Effects of Grazing Management and Buffer Strips on Metal Runoff from Pastures Fertilized with Poultry Litter.

    Science.gov (United States)

    Pilon, C; Moore, P A; Pote, D H; Martin, J W; DeLaune, P B

    2017-03-01

    Metal runoff from fields fertilized with poultry litter may pose a threat to aquatic systems. Buffer strips located adjacent to fields may reduce nutrients and solids in runoff. However, scant information exists on the long-term effects of buffer strips combined with grazing management on metal runoff from pastures. The objective of this study was to assess the 12-yr impact of grazing management and buffer strips on metal runoff from pastures receiving poultry litter. The research was conducted using 15 watersheds (25 m wide and 57 m long) with five treatments: hayed (H), continuously grazed (CG), rotationally grazed (R), rotationally grazed with a buffer strip (RB), and rotationally grazed with a fenced riparian buffer strip (RBR). Poultry litter was applied annually in spring at 5.6 Mg ha. Runoff samples were collected after every rainfall event. Aluminum (Al) and iron (Fe) concentrations were strongly and positively correlated with total suspended solids, indicating soil erosion was the primary source. Soluble Al and Fe were not related to total Al and Fe. However, there was a strong positive correlation between soluble and total copper (Cu) concentrations. The majority of total Cu and zinc was in water-soluble form. The CG treatment had the highest metal concentrations and loads of all treatments. The RBR and H treatments resulted in lower concentrations of total Al, Cu, Fe, potassium, manganese, and total organic carbon in the runoff. Rotational grazing with a fenced riparian buffer and converting pastures to hayfields appear to be effective management systems for decreasing concentrations and loads of metals in surface runoff from pastures fertilized with poultry litter. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  16. Thickness-Dependent Properties of YBCO Films Grown on GZO/CLO-Buffered NiW Substrates

    DEFF Research Database (Denmark)

    Malmivirta, M.; Huhtinen, H.; Yue, Zhao

    2017-01-01

    To study the role of novel Gd2Zr2O7/Ce0.9La0.1O2 buffer layer structure on a biaxially textured NiW substrate, a set of YBa2Cu3O7−δ (YBCO) films with different thicknesses were prepared by pulsed laser deposition (PLD). Interface imperfections as well as thickness-dependent structural properties...... were observed in the YBCO thin films. The structure is also reflected into the improved superconducting properties with the highest critical current densities in films with intermediate thicknesses. Therefore,it can be concluded that the existing buffer layers need more optimization before they can...

  17. Metal substrate effects on the thermochemistry of active brazing interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Arroyave, Raymundo; Eagar, Thomas W

    2003-09-15

    This work investigates the effects of the metal substrate on the thermochemistry of active brazing alloys during ceramic/metal joining applications. The thermodynamics and kinetics of the interactions between the metal substrate and the braze alloy are examined. Numerical simulations are used to rationalize experimental observations reported elsewhere. It is shown that using Ni metal substrates at temperatures much higher than the liquidus of the brazing alloys can dramatically decrease the chemical activity of Ti in Cu-based brazing alloys. This effect is much less intense when Fe-metal substrates are in contact with the same active brazing alloy systems. It is additionally proven that the time scales necessary to observe such detrimental decrease in chemical activity are on the order of minutes.

  18. Ligand-enhanced electrokinetic remediation of metal-contaminated marine sediments with high acid buffering capacity.

    Science.gov (United States)

    Masi, Matteo; Iannelli, Renato; Losito, Gabriella

    2016-06-01

    The suitability of electrokinetic remediation for removing heavy metals from dredged marine sediments with high acid buffering capacity was investigated. Laboratory-scale electrokinetic remediation experiments were carried out by applying two different voltage gradients to the sediment (0.5 and 0.8 V/cm) while circulating water or two different chelating agents at the electrode compartments. Tap water, 0.1 M citric acid and 0.1 M ethylenediaminetetraacetic acid (EDTA) solutions were used respectively. The investigated metals were Zn, Pb, V, Ni and Cu. In the unenhanced experiment, the acid front could not propagate due to the high acid buffering capacity of the sediments; the production of OH(-) ions at the cathode resulted in a high-pH environment causing the precipitation of CaCO3 and metal hydroxides. The use of citric acid prevented the formation of precipitates, but solubilisation and mobilisation of metal species were not sufficiently achieved. Metal removal was relevant when EDTA was used as the conditioning agent, and the electric potential was raised up to 0.8 V/cm. EDTA led to the formation of negatively charged complexes with metals which migrated towards the anode compartment by electromigration. This result shows that metal removal from sediments with high acid buffering capacity may be achieved by enhancing the electrokinetic process by EDTA addition when the acidification of the medium is not economically and/or environmentally sustainable.

  19. Stress of electroless copper deposits on insulating and metal substrates

    Energy Technology Data Exchange (ETDEWEB)

    Brüning, Ralf, E-mail: rbruening@mta.ca [Physics Department, Mount Allison University, Sackville, New Brunswick E4L 1E6 (Canada); Sibley, Allison; Sharma, Tanu; Brown, Delilah A.; Demay, Thibault [Physics Department, Mount Allison University, Sackville, New Brunswick E4L 1E6 (Canada); Brüning, Frank; Bernhard, Tobias [Atotech Deutschland GmbH, Erasmusstrasse 20, 10553 Berlin (Germany)

    2014-08-28

    In the fabrication of printed circuit boards, electroless copper is plated on insulating substrates. However, data for film stress by substrate bending are frequently obtained with metal substrates. We compare the stress evolution on an insulating substrate (acrylonitrile butadiene styrene) with results from commercial Ni–Fe and Cu–Fe alloy test strips, as well as X-ray diffraction based strain data. Tests were done with two plating bath formulations, one with and one without added nickel. Substrate type and condition determine the stress near the beginning of plating. Stress of the Ni-free films depends more strongly on the substrate material. Further, when the samples are cooled from the bath operating temperature to room temperature, the thermal contraction of the insulating substrate compresses the plated thin copper film. The measured stress change agrees with the change predicted by calculation. Data correction methods are discussed, and other substrate materials can be tested readily with the method employed here. - Highlights: • We report stress of electroless Cu deposits on insulating and metal substrates. • The final deposit stress is substrate-independent. • The final deposit stress and the X-ray diffraction based strain agree. • The stress change due to the thermal contraction of the substrate is observed. • Plating bath type, substrate and surface preparation alter the stress.

  20. Direct electroplated metallization on indium tin oxide plastic substrate.

    Science.gov (United States)

    Hau, Nga Yu; Chang, Ya-Huei; Huang, Yu-Ting; Wei, Tzu-Chien; Feng, Shien-Ping

    2014-01-14

    Looking foward to the future where the device becomes flexible and rollable, indium tin oxide (ITO) fabricated on the plastic substrate becomes indispensable. Metallization on the ITO plastic substrate is an essential and required process. Electroplating is a cost-effective and high-throughput metallization process; however, the poor surface coverage and interfacial adhesion between electroplated metal and ITO plastic substrate limits its applications. This paper develops a new method to directly electroplate metals having strong adhesion and uniform deposition on an ITO plastic substrate by using a combination of 3-mercaptopropyl-trimethoxysilane (MPS) self-assembled monolayers (SAMs) and a sweeping potential technique. An impedance capacitive analysis supports the proposed bridging link model for MPS SAMs at the interface between the ITO and the electrolyte.

  1. Investigations into alterntive substrate, absorber, and buffer layer processing for Cu(In,Ga)Se{sub 2}-based solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Tuttle, J.R.; Berens, T.A.; Keane, J. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-05-01

    High-performance Cu(In,Ga)Se{sub 2}(CIGS)-based solar cells are presently fabricated within a narrow range of processing options. In this contribution, alternative substrate, absorber, and buffer layer processing is considered. Cell performance varies considerably when alternative substrates are employed. These variations are narrowed with the addition of Na via a Na{sub 2}S compound. Sputtered and electrodeposited CIGS precursors and completed absorbers show promise as alternatives to evaporation. A recrystallization process is required to improve their quality. (In,Ga){sub y}Se buffer layers contribute to cell performance above 10. Further improvements in these alternatives will lead to combined cell performance greater than 10% in the near term.

  2. Control of threading dislocations by strain engineering in GaInP buffers grown on GaAs substrates

    Energy Technology Data Exchange (ETDEWEB)

    Li, K.L., E-mail: klli2010@sinano.ac.cn [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Sun, Y.R. [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Dong, J.R. [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); He, Y.; Zeng, X.L. [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhao, Y.M.; Yu, S.Z.; Zhao, C.Y. [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China)

    2015-10-30

    High quality strain-relaxed In0.3Ga0.7As layers with threading dislocation density about 2 × 10{sup 6} cm{sup −2} and root-mean-square surface roughness below 8.0 nm were obtained on GaAs substrates using compositionally undulating step-graded Ga{sub 1−x}In{sub x}P (x = 0.48–0.78) buffers. The transmission electron microscopy results reveal that the conventional step-graded GaInP buffers produce high density dislocation pile-ups, which are induced by the blocking effect of the nonuniform misfit dislocation strain field and crosshatched surface on the gliding of threading dislocations. In contrast, due to strain compensation, insertion of the tensile GaInP layers decreases the surface roughness and promotes dislocation annihilation in the interfaces, and eventually reduces the threading dislocation density. This provides a promising way to achieve a virtual substrate with the desired lattice parameter for metamorphic device applications. - Highlights: • Metamorphic GaInP buffers were grown by metal–organic chemical vapor deposition. • The compositionally undulating buffers effectively reduce the threading dislocation density. • High quality strain-relaxed In{sub 0.3}Ga{sub 0.7}As layers were obtained.

  3. High Quality GaAs Epilayers Grown on Si Substrate Using 100 nm Ge Buffer Layer

    Directory of Open Access Journals (Sweden)

    Wei-Cheng Kuo

    2016-01-01

    Full Text Available We present high quality GaAs epilayers that grow on virtual substrate with 100 nm Ge buffer layers. The thin Ge buffer layers were modulated by hydrogen flow rate from 60 to 90 sccm to improve crystal quality by electron cyclotron resonance chemical vapor deposition (ECR-CVD at low growth temperature (180°C. The GaAs and Ge epilayers quality was verified by X-ray diffraction (XRD and spectroscopy ellipsometry (SE. The full width at half maximum (FWHM of the Ge and GaAs epilayers in XRD is 406 arcsec and 220 arcsec, respectively. In addition, the GaAs/Ge/Si interface is observed by transmission electron microscopy (TEM to demonstrate the epitaxial growth. The defects at GaAs/Ge interface are localized within a few nanometers. It is clearly showed that the dislocation is well suppressed. The quality of the Ge buffer layer is the key of III–V/Si tandem cell. Therefore, the high quality GaAs epilayers that grow on virtual substrate with 100 nm Ge buffer layers is suitable to develop the low cost and high efficiency III–V/Si tandem solar cells.

  4. Study of High Quality Indium Nitride Films Grown on Si(100 Substrate by RF-MOMBE with GZO and AlN Buffer Layers

    Directory of Open Access Journals (Sweden)

    Wei-Chun Chen

    2012-01-01

    Full Text Available Wurtzite structure InN films were prepared on Si(100 substrates using radio-frequency metal-organic molecular beam epitaxy (RF-MOMBE system. Ga-doped ZnO (GZO and Amorphous AlN (a-AlN film were used as buffer layers for InN films growth. Structural, surface morphology and optical properties of InN films were investigated by X-ray diffraction (XRD, field emission scanning electron microscopy (FE-SEM, transmission electron microscopy (TEM, and photoluminescence (PL. XRD results indicated that all InN films exhibited preferred growth orientation along the c-axis with different intermediate buffers. TEM images exhibit the InN/GZO growth by two-dimensional mode and thickness about 900 nm. Also, the InN films can be obtained by growth rate about ~1.8 μm/h. Optical properties indicated that the band gap of InN/GZO is about 0.79 eV. These results indicate that the control of buffer layer is essential for engineering the growth of InN on silicon wafer.

  5. Hot-Dipped Metal Films as Epitaxial Substrates

    Science.gov (United States)

    Shlichta, P. J.

    1985-01-01

    Multistep process forms semiconductor devices on macrocrystalline films of cadmium or zinc. Solar-cell fabrication processes use hot-dipped macrocrystalline films on low-cost sheet-metal base as substrates for epitaxy. Epitaxial layers formed by variety of methods of alternative sequence paths. Solar cells made economically by forming desired surface substance directly on metal film by chemical reactions.

  6. Epitaxial NbN/AlN/NbN tunnel junctions on Si substrates with TiN buffer layers

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Rui [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Makise, Kazumasa; Terai, Hirotaka [Advanced ICT Research Institute, National Institute of Information and Communications Technology (Japan); Zhang, Lu [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); Wang, Zhen, E-mail: zwang@mail.sim.ac.cn [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Shanghai Tech University, Shanghai 201210 (China)

    2016-06-15

    We have developed epitaxial NbN/AlN/NbN tunnel junctions on Si (100) substrates with a TiN buffer layer. A 50-nm-thick (200)-oriented TiN thin film was introduced as the buffer layer for epitaxial growth of NbN/AlN/NbN trilayers on Si substrates. The fabricated NbN/AlN/NbN junctions demonstrated excellent tunneling properties with a high gap voltage of 5.5 mV, a large I{sub c}R{sub N} product of 3.8 mV, a sharp quasiparticle current rise with a ΔV{sub g} of 0.4 mV, and a small subgap leakage current. The junction quality factor R{sub sg}/R{sub N} was about 23 for the junction with a J{sub c} of 47 A/cm{sup 2} and was about 6 for the junction with a J{sub c} of 3.0 kA/cm{sup 2}. X-ray diffraction and transmission electron microscopy observations showed that the NbN/AlN/NbN trilayers were grown epitaxially on the (200)-orientated TiN buffer layer and had a highly crystalline structure with the (200) orientation.

  7. Epitaxial NbN/AlN/NbN tunnel junctions on Si substrates with TiN buffer layers

    Directory of Open Access Journals (Sweden)

    Rui Sun

    2016-06-01

    Full Text Available We have developed epitaxial NbN/AlN/NbN tunnel junctions on Si (100 substrates with a TiN buffer layer. A 50-nm-thick (200-oriented TiN thin film was introduced as the buffer layer for epitaxial growth of NbN/AlN/NbN trilayers on Si substrates. The fabricated NbN/AlN/NbN junctions demonstrated excellent tunneling properties with a high gap voltage of 5.5 mV, a large IcRN product of 3.8 mV, a sharp quasiparticle current rise with a ΔVg of 0.4 mV, and a small subgap leakage current. The junction quality factor Rsg/RN was about 23 for the junction with a Jc of 47 A/cm2 and was about 6 for the junction with a Jc of 3.0 kA/cm2. X-ray diffraction and transmission electron microscopy observations showed that the NbN/AlN/NbN trilayers were grown epitaxially on the (200-orientated TiN buffer layer and had a highly crystalline structure with the (200 orientation.

  8. Structural and electrical properties of biaxially textured YBa{sub 2}Cu{sub 3}O{sub 7-x} thin films on buffered Ni-based alloy substrates.

    Energy Technology Data Exchange (ETDEWEB)

    Li, M.; Ma, B.; Jee, Y. A.; Fisher, B. L.; Balachandran, U.

    2000-12-07

    Oxide high-T{sub c} superconducting wires and tapes with high critical current density (J{sub c}) are essential in future electrical power applications. Recently, YBa{sub 2}Cu{sub 3}O{sub 7{minus}x} (YBCO) thin films grown on Ni-based alloy tapes have attracted intense interest because of their promise for these applications. In order to achieve high J{sub c}, buffer layers are necessary for fabricating biaxially aligned YBCO thin films. In our studies, yttria-stabilized zirconia (YSZ) layers were deposited on Ni-based alloy substrate by ion-beam assisted deposition, and CeO{sub 2} buffer layers were subsequently deposited on the YSZ layer by pulsed laser deposition (PLD) or electron beam evaporation. In addition, MgO layers were deposited on Ni-based alloy substrates by inclined substrate deposition. Finally, biaxially textured YBCO thin films were deposited on these buffered metallic substrates by PLD under optimized conditions. The orientation and in-plane textures of YBCO and the buffer layers were characterized by X-ray diffraction {Theta}/2{Theta} scan, {phi}-scan, and pole figure analysis. The superconductive transition features were examined by measuring inductive T{sub c} and transport J{sub c}.

  9. Occurrence of cubic GaN and strain relaxation in GaN buffer layers grown by low-pressure metalorganic vapor phase epitaxy on (0001) sapphire substrates

    Science.gov (United States)

    Cheng, Lisen; Zhou, Kuan; Zhang, Ze; Zhang, Guoyi; Yang, Zhijian; Tong, Yuzhen

    1999-02-01

    Investigations on GaN buffer layers grown by low-pressure metalorganic vapor phase epitaxy on (0001) sapphire substrates indicated that the mechanisms by way of which GaN buffer layers relax stresses introduced by the lattice mismatch and thermal expansion coefficient difference between GaN epilayer and sapphire substrate are related to both the crystallographic structure of GaN and thickness of the buffer layers. Beside forming misfit dislocations, mismatch-induced stresses can also be relaxed by forming stacking faults and microtwin boundaries parallel to (11-1) of GaN near the interface between GaN and sapphire substrate in cubic GaN buffer layers. It was found that, in cubic GaN buffer layers, there exists a critical thickness within which the stacking faults and/or microtwin boundaries parallel to (11-1) of GaN can be formed. This critical value is determined to be 50 nm.

  10. Anti-phase boundaries-Free GaAs epilayers on "quasi-nominal" Ge-buffered silicon substrates

    Science.gov (United States)

    Bogumilowicz, Y.; Hartmann, J. M.; Cipro, R.; Alcotte, R.; Martin, M.; Bassani, F.; Moeyaert, J.; Baron, T.; Pin, J. B.; Bao, X.; Ye, Z.; Sanchez, E.

    2015-11-01

    We have obtained Anti-Phase Boundary (APB) free GaAs epilayers on "quasi-nominal" (001) silicon substrates, while using a thick germanium strain relaxed buffer between the GaAs layer and the silicon substrate in order to accommodate the 4% lattice mismatch between the two. As silicon (001) substrates always have a small random offcut angle from their nominal surface plane, we call them "quasi-nominal." We have focused on the influence that this small (≤0.5°) offcut angle has on the GaAs epilayer properties, showing that it greatly influences the density of APBs. On 0.5° offcut substrates, we obtained smooth, slightly tensile strained (R = 106%) GaAs epilayers that were single domain (e.g., without any APB), showing that it is not necessary to use large offcut substrates, typically 4° to 6°, for GaAs epitaxy on silicon. These make the GaAs layers more compatible with the existing silicon manufacturing technology that uses "quasi-nominal" substrates.

  11. Preparation of a Novel Ce0.9La0.1O2/Gd2Zr2O7 Buffer Layer Stack on NiW Alloy Substrates by the MOD Route

    DEFF Research Database (Denmark)

    Yue, Zhao; Grivel, Jean-Claude; Abrahamsen, Asger Bech

    2011-01-01

    an excellent lattice match with the superconductor layer, and to employ 200 nm thick ${\\rm Gd}_{2}{\\rm Zr}_{2}{\\rm O}_{7}$ film as barrier layer. The effect of thermal cycling on the texture and morphology of the crystallized films and NiW substrate is discussed in detail. The texture quality and the epitaxial......An optimized buffer layer architecture prepared by a metal organic deposition method on biaxially textured metallic substrate is proposed and developed successfully. The major achievement of this work is to choose a ${\\rm Ce}_{0.9}{\\rm La}_{0.1}{\\rm O}_{2}$ layer as cap layer that possesses...... relationship between the buffer layer stack and the metallic substrate were studied by synchrotron x-ray diffraction. Well textured, smooth and crack-free ${\\rm Ce}_{0.9}{\\rm La}_{0.1}{\\rm O}_{2}/{\\rm Gd}_{2}{\\rm Zr}_{2}{\\rm O}_{7}$ buffer layer stacks are obtained, demonstrating the possibility of producing...

  12. The W-W02 Oxygen Fugacity Buffer at High Pressures and Temperatures: Implications for f02 Buffering and Metal-silicate Partitioning

    Science.gov (United States)

    Shofner, G. A.; Campbell, A. J.; Danielson, L.; Righter, K.

    2013-01-01

    Oxygen fugacity (fO2) controls multivalent phase equilibria and partitioning of redox-sensitive elements, and it is important to understand this thermodynamic parameter in experimental and natural systems. The coexistence of a metal and its oxide at equilibrium constitutes an oxygen buffer which can be used to control or calculate fO2 in high pressure experiments. Application of 1-bar buffers to high pressure conditions can lead to inaccuracies in fO2 calculations because of unconstrained pressure dependencies. Extending fO2 buffers to pressures and temperatures corresponding to the Earth's deep interior requires precise determinations of the difference in volume (Delta) V) between the buffer phases. Synchrotron x-ray diffraction data were obtained using diamond anvil cells (DAC) and a multi anvil press (MAP) to measure unit cell volumes of W and WO2 at pressures and temperatures up to 70 GPa and 2300 K. These data were fitted to Birch-Murnaghan 3rd-order thermal equations of state using a thermal pressure approach; parameters for W are KT = 306 GPa, KT' = 4.06, and aKT = 0.00417 GPa K-1. Two structural phase transitions were observed for WO2 at 4 and 32 GPa with structures in P21/c, Pnma and C2/c space groups. Equations of state were fitted for these phases over their respective pressure ranges yielding the parameters KT = 190, 213, 300 GPa, KT' = 4.24, 5.17, 4 (fixed), and aKT = 0.00506, 0.00419, 0.00467 GPa K-1 for the P21/c, Pnma and C2/c phases, respectively. The W-WO2 buffer (WWO) was extended to high pressure by inverting the W and WO2 equations of state to obtain phase volumes at discrete pressures (1-bar to 100 GPa, 1 GPa increments) along isotherms (300 to 3000K, 100 K increments). The slope of the absolute fO2 of the WWO buffer is positive with increasing temperature up to approximately 70 GPa and is negative above this pressure. The slope is positive along isotherms from 1000 to 3000K with increasing pressure up to at least 100 GPa. The WWO buffer is at

  13. [Acid buffer capacity of sewage sludge barrier for immobilization of heavy metals].

    Science.gov (United States)

    Zhang, Hu-Yuan; Ju, Yuan-Yuan; Fan, Zhi-Ming; Wang, Bao

    2010-12-01

    Employing the anaerobic activities of microorganisms, sewage sludge can be used as a barrier to immobilize the heavy metals leached from tailings. Due to the interactions between sewage sludge barrier and acid mine drainage (AMD), it is possible that the heavy metals that have been immobilized previously might be released out. The acid buffering capacity (ABC) of sewage sludge suspensions with various anaerobic incubation time and the effect of ABC on the mobility of heavy metals were investigated by acid titration tests. Test results showed that ABC of sewage sludge suspensions was increased with the solid-liquid ratio of the suspensions and the anaerobic incubation time, and that carbonate and organics play an important role in acid buffer of sewage sludge suspensions. During the acid titration test, Zn, Pb and Cu were released out obviously following the order of Zn > Cu > Pb as pH was decreased less than 6.2. A mathematical model was established to predict the ABC consumption of the sewage sludge barrier under AMD penetration condition. The simulation results showed that a sewage sludge barrier with 2.0 m thickness, even undergoing 666-years acidification by AMD under 10.0 m water head, can maintain a condition of pH > or = 6.2 and, therefore, keep immobilize the heavy metals of AMD in the barrier.

  14. Germanium thin film integration on silicon substrates via oxide heterostructure buffers

    Energy Technology Data Exchange (ETDEWEB)

    Giussani, Alessandro

    2010-02-15

    Following the GeOI heteroepitaxial approach, Ge was deposited by molecular beam epitaxy (MBE) on PrO{sub 2}(111)/Si(111) support systems, and the initial growth stages were studied by means of in-situ reflection high energy electron diffraction (RHEED), and X-ray and ultra-violet photoelectron spectroscopy (XPS and UPS, respectively). It was shown that in the first evaporation stages an amorphous GeO{sub 2}-like layer forms as a result of the Ge adatom interaction with the PrO{sub 2} substrate, namely the diffusion of lattice oxygen from the dielectric into the growing semiconductor deposit. In consequence the PrO{sub 2}(111) buffer oxide is fully reduced to an oxygen-deficient cub (cubic) Pr{sub 2}O{sub 3}(111) film structure. Since no oxidizing species are available in the process anymore, the Ge oxide layer converts under continuous Ge evaporation to GeO, which is volatile at the deposition temperature ({proportional_to}550 C). The sublimation of GeO uncovers the cub-Pr{sub 2}O{sub 3}(111) surface, which finally provides a thermodynamically stable template for the heteroepitaxial growth of elemental Ge. A Volmer-Weber growth mode is initially observed, which, by properly tuning the deposition parameters, results after island coalescence in the formation of a closed and flat Ge/cub-Pr{sub 2}O{sub 3}/Si heterostructure. Ge epilayer thickness (in the range 20-1000 nm) and morphology were studied ex-situ by means of X-ray reflectivity (XRR) and secondary electron microscopy (SEM). Dynamic secondary ion mass spectroscopy (D-SIMS) was employed to study the chemical compositions of the Ge films, which turned out to be free from Si and Pr impurities at the sensitivity of some parts-per-billion (ppbs), even after supplying a high thermal budget. Then, laboratory- and synchrotron-based X-ray diffraction (XRD) analyses were performed to assess the epitaxial relationship and the defect structure of the Ge epifilms. It was demonstrated that the Ge layers grow single

  15. Comparison of different pathways in metamorphic graded buffers on GaAs substrate: Indium incorporation with surface roughness

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rahul, E-mail: rkp203@gmail.com [Advanced Technology Development Centre, Indian Institute of Technology, Kharagpur 721302 (India); Mukhopadhyay, P. [Rajendra Mishra School of Engineering Entrepreneurship, Indian Institute of Technology, Kharagpur 721302 (India); Bag, A.; Jana, S. Kr. [Advanced Technology Development Centre, Indian Institute of Technology, Kharagpur 721302 (India); Chakraborty, A. [Department of Electronics and Electrical Communication Engineering, Indian Institute of Technology, Kharagpur 721 302 (India); Das, S.; Mahata, M. Kr. [Advanced Technology Development Centre, Indian Institute of Technology, Kharagpur 721302 (India); Biswas, D. [Department of Electronics and Electrical Communication Engineering, Indian Institute of Technology, Kharagpur 721 302 (India)

    2015-01-01

    Highlights: • In(Al,Ga)As metamorphic buffers on GaAs have been grown. • Surface morphology, strain relaxation and compositional variation have been studied. • Al containing buffers shows inferior surface roughness. • Surface roughness modulates the indium incorporation rate. - Abstract: In this work, compositionally graded In(Al,Ga)As metamorphic buffers (MBs) on GaAs substrate have been grown by MBE through three different paths. A comparative study has been done to comprehend the effect of underlying MB on the constant composition InAlAs healing layer by analyzing the relaxation behaviour, composition and surface morphology of the grown structures. The compositional variation between the constant composition healing layers on top of graded MB has been observed in all three samples although the growth conditions have been kept same. Indium incorporation rate has been found to be dependent on underlying MB. By combining the result of atomic force microscopy, photo-luminescence and X-ray reciprocal space mapping, varying surface roughness has been proposed as the probable driving force behind different Indium incorporation rate.

  16. Strain Effects in Epitaxial VO2 Thin Films on Columnar Buffer-Layer TiO2/Al2O3 Virtual Substrates.

    Science.gov (United States)

    Breckenfeld, Eric; Kim, Heungsoo; Burgess, Katherine; Charipar, Nicholas; Cheng, Shu-Fan; Stroud, Rhonda; Piqué, Alberto

    2017-01-18

    Epitaxial VO2/TiO2 thin film heterostructures were grown on (100) (m-cut) Al2O3 substrates via pulsed laser deposition. We have demonstrated the ability to reduce the semiconductor-metal transition (SMT) temperature of VO2 to ∼44 °C while retaining a 4 order of magnitude SMT using the TiO2 buffer layer. A combination of electrical transport and X-ray diffraction reciprocal space mapping studies help examine the specific strain states of VO2/TiO2/Al2O3 heterostructures as a function of TiO2 film growth temperatures. Atomic force microscopy and transmission electron microscopy analyses show that the columnar microstructure present in TiO2 buffer films is responsible for the partially strained VO2 film behavior and subsequently favorable transport characteristics with a lower SMT temperature. Such findings are of crucial importance for both the technological implementation of the VO2 system, where reduction of its SMT temperature is widely sought, as well as the broader complex oxide community, where greater understanding of the evolution of microstructure, strain, and functional properties is a high priority.

  17. Tuning of large piezoelectric response in nanosheet-buffered lead zirconate titanate films on glass substrates

    NARCIS (Netherlands)

    Chopra, A.; Bayraktar, Muharrem; Nijland, Maarten; ten Elshof, Johan E.; Bijkerk, Frederik; Rijnders, Augustinus J.H.M.

    2017-01-01

    Renewed interest has been witnessed in utilizing the piezoelectric response of PbZr0.52Ti0.48O3 (PZT) films on glass substrates for applications such as adaptive optics. Accordingly, new methodologies are being explored to grow well-oriented PZT thin films to harvest a large piezoelectric response.

  18. Photoluminescence studies of GaN films on Si(111) substrate by using an AlN buffer control

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Doek Kyu; Park, Choon Bae [Wonkwang University, Iksan (Korea, Republic of)

    2005-12-15

    The optical properties of GaN epitaxial layers grown on silicon (111) substrates with AlN buffer layers by using metalorganic vapor phase epitaxy were investigated for various values of the buffer layer's thickness. As the AlN thickness increased, the peak position of the free exciton of the GaN films was red-shifted linearly and the full width at half maximum (FWHM) of the free-exciton peak decreased. The red-shift of the free-exciton peak was attributed to cracks due to heavy stress. In 80-nm-thick AlN, the strong band-edge emission of GaN on Si (111) was observed with the full width at half maximum of the bound exciton line being as low as 17 mev at 13 K. The variations of Varshni's fitting parameter and the activation energy of the free exciton with the AlN thickness were evaluated for GaN films

  19. Preparation of SmBiO{sub 3} buffer layer on YSZ substrate by an improved chemical solution deposition route

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaolei [Key Laboratory of Advanced Technologies of Materials (Ministry of Education of China), Superconductivity and New Energy R& D Center, Mail Stop 165#, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Pu, Minghua, E-mail: mhpu@home.swjtu.edu.cn [Key Laboratory of Advanced Technologies of Materials (Ministry of Education of China), Superconductivity and New Energy R& D Center, Mail Stop 165#, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Zhao, Yong [Key Laboratory of Advanced Technologies of Materials (Ministry of Education of China), Superconductivity and New Energy R& D Center, Mail Stop 165#, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); School of Materials Science and Engineering, University of New South Wale, Sydney, NSW 2052 (Australia)

    2016-12-15

    Highlights: • The proper conditions for SBO growth are 794 °C for 60 min in flowing Ar gas, the temperature of epitaxial growth is relatively low. • The total time by SSD technique for organic solvent removing, salts decomposition and layer growth is not up to 2 h, which are much less than that needed for traditional CSD of over 10 h. • SBO layer on YSZ prepared by SSD technique are suitable for the growth of YBCO, The results may be the usable reference for continuous preparation of SBO buffer layer on IBAD-YSZ/Ni-based alloy tapes. - Abstract: A quick route for chemical solution deposition (CSD) has been developed to prepare SmBiO{sub 3} (SBO) layers on yttria stabilized zirconia (YSZ) substrates rapidly by using of solid state decomposition (SSD) technique. The proper conditions for volatilization of lactic acid, which as solvent in precursor coated layer, and SBO growth are 115°C for 30 min and 794°C for 60 min in flowing Ar gas. The coated layers are amorphous structure of mixture oxides and quasi-crystal structure of SBO before and after growth, respectively. The total time by this quick CSD route for organic solvent volatilization, salts decomposed and layer growth is not up to 2 h, which are much less than that needed for traditional CSD of over 10 h. SBO layer is directly epitaxial growth on YSZ substrate without any lattice rotation. SBO layer prepared by this quick route as well as that by traditional route are suitable for the growth of YBCO. The superconducting transition temperature and critical current density of the coated YBCO layer on SBO/YSZ obtained by this quick route are up to 90 K and 1.66 MA/cm{sup 2}. These results may be the usable reference for continuous preparation of SBO buffer layer on IBAD-YSZ/Ni-based alloy tapes.

  20. [Oxidation buffer capacity of sewage sludge barrier for immobilization of heavy metals].

    Science.gov (United States)

    Zhang, Hu-Yuan; Fan, Zhi-Ming; Wang, Bao; Ju, Yuan-Yuan

    2010-11-01

    Benefit from the microbial activities especially the anaerobic sulfate reduction processes, sewage sludge could be used as a barrier to immobilize the heavy metals leached from tailings. With respect to the redox reaction between sewage sludge and acid mine drainage (AMD), oxidation titration test was carried out to study the effect of oxidation buffer capacity (OBC) of sewage sludge on the immobilization of heavy metals. Test results showed that OBC of sludge suspensions was decreased slightly with the solid-liquid ratio of the suspensions, but increased with the anaerobic incubation time, and that more than 50% of OBC was contributed by the sludge existed in strongly-reduction conditions (Eh or = - 150 mV, while Cu and Pb released obviously when Eh > or = 150 mV. According to the test results, a mathematical model was established to predict the OBC consumption of the sludge barrier under AMD penetrating conditions. The simulation results showed that a sludge barrier with 2m thickness, even undergone 38 787-years oxidation by AMD under 10m water head, keep in a strongly-reduced condition and, therefore, promote an immobilization of heavy metals from AMD in the barrier.

  1. Interaction between coordinated metal ions and a metal substrate: Differently substituted cobalt porphyrins on Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Yun; Buchner, Florian; Schmid, Martin; Kellner, Ina; Vollnhals, Florian; Marbach, Hubertus; Steinrueck, Hans-Peter; Gottfried, J. Michael [Universitaet Erlangen-Nuernberg, Lehrstuhl fuer Physikalische Chemie II, Egerlandstr. 3, 91058 Erlangen (Germany)

    2009-07-01

    Adsorbed metalloporphyrins are of increasing interest due to their potential applications in heterogeneous catalysis and in sensor systems. Previous studies from our group have suggested the existence of an electronic interaction between the metal centers of the adsorbed porphyrin complexes of iron and cobalt and the underlying substrate surface, which plays an important role in modifying the electronic structure and, thereby, the reactivity of these metal centers. However, with the previously used tetraphenylporphyrin (TPP) ligands, the adsorbed complexes undergo saddle-shape distortion, which could also influence the electronic structure. To separate the effects of distortion on the one hand and the coupling to the substrate on the other, we have studied cobalt octaethylporphyrin, which adsorbs in a flat, undistorted conformation on Ag(111). Comparison of our XPS, UPS, and STM results with previous CoTPP data confirms that indeed the metal center plays an essential role in the electronic interaction between the porphyrin complexes and the substrate.

  2. Cube Texture Formation of Cu-33at.%Ni Alloy Substrates and CeO2 Buffer Layer for YBCO Coated Conductors

    DEFF Research Database (Denmark)

    Tian, Hui; Li, Suo Hong; Ru, Liang Ya

    2014-01-01

    Cube texture formation of Cu-33 at.%Ni alloy substartes and CeO2 buffer layer prepared by chemical solution deposition on the textured substrate were investigated by electron back scattered diffraction (EBSD) and XRD technics systematically. The results shown that a strong cube textured Cu-33at.......%Ni alloy substrate with the cube texture fraction of 99.8 % (cube texture fraction...

  3. Assessment of Automotive Coatings Used on Different Metallic Substrates

    Directory of Open Access Journals (Sweden)

    W. Bensalah

    2014-01-01

    Full Text Available Four epoxy primers commonly used in the automotive industry were applied by gravity pneumatic spray gun over metallic substrates, specifically, steel, electrogalvanized steel, hot-dip galvanized steel, and aluminum. A two-component polyurethane resin was used as topcoat. To evaluate the performance of the different coating systems, the treated panels were submitted to mechanical testing using Persoz hardness, impact resistance, cupping, lattice method, and bending. Tribological properties of different coating systems were conducted using pin on disc machine. Immersion tests were carried out in 5% NaCl and immersion tests in 3% NaOH solutions. Results showed which of the coating systems is more suitable for each substrate in terms of mechanical, tribological, and anticorrosive performance.

  4. Preparation of epitaxial YBa 2Cu 3O 7- y films on CeO 2-buffered yttria-stabilized zirconia substrates by fluorine-free metalorganic deposition

    Science.gov (United States)

    Tsukada, Kenichi; Yamaguchi, Iwao; Sohma, Mitsugu; Kondo, Wakichi; Kamiya, Kunio; Kumagai, Toshiya; Manabe, Takaaki

    2007-07-01

    Epitaxial YBa 2Cu 3O 7- y (YBCO) films of 120-550 nm thickness have been prepared by fluorine-free metalorganic deposition using a metal acetylacetonate-based coating solution on yttria-stabilized zirconia (YSZ) substrates with an evaporated CeO 2 buffer layer. The YBCO films were highly (0 0 1)-oriented by X-ray diffraction θ-2 θ scanning and ϕ scanning. The YBCO films 120-400 nm in thickness demonstrated high critical current densities ( Jc) with an average in excess of 3 MA/cm 2 at 77 K using an inductive method. In particular, a 210-nm-thick film showed a Jc of 4.5 MA/cm 2. These excellent properties are attributed to the high crystallinity, small in-plane fluctuation due to high epitaxy and to the microstructure free from grain boundaries in the YBCO films. Further increase of film thickness increased the fraction of irregularities, i.e., precipitates and micropores, in the film surfaces, resulting in lower Jc values.

  5. Enhanced electrical and magnetic properties in La0.7Sr0.3MnO3 thin films deposited on CaTiO3-buffered silicon substrates

    Directory of Open Access Journals (Sweden)

    C. Adamo

    2015-06-01

    Full Text Available We investigate the suitability of an epitaxial CaTiO3 buffer layer deposited onto (100 Si by reactive molecular-beam epitaxy (MBE for the epitaxial integration of the colossal magnetoresistive material La0.7Sr0.3MnO3 with silicon. The magnetic and electrical properties of La0.7Sr0.3MnO3 films deposited by MBE on CaTiO3-buffered silicon (CaTiO3/Si are compared with those deposited on SrTiO3-buffered silicon (SrTiO3/Si. In addition to possessing a higher Curie temperature and a higher metal-to-insulator transition temperature, the electrical resistivity and 1/f noise level at 300 K are reduced by a factor of two in the heterostructure with the CaTiO3 buffer layer. These results are relevant to device applications of La0.7Sr0.3MnO3 thin films on silicon substrates.

  6. Enhanced electrical and magnetic properties in La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films deposited on CaTiO{sub 3}-buffered silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Adamo, C. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853-1501 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Méchin, L.; Guillet, B.; Wu, S.; Routoure, J.-M. [Groupe de Recherche en Informatique, Image, Automatique et Instrumentation de Caen, (GREYC-UMR 6072), CNRS-ENSICAEN—Université de Caen Basse-Normandie, 6 Boulevard Maréchal Juin, 14050 Caen Cedex (France); Heeg, T. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853-1501 (United States); Katz, M.; Pan, X. Q. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Mercone, S. [Laboratoire de Sciences des Procédés et des Matériaux, UPR3407, CNRS, Institut Galilee, Universite Paris-Nord, Villetaneuse (France); Schubert, J.; Zander, W. [Peter Grünberg Institute (PGI9-IT), JARA-Fundamentals of Future Information Technology, Research Centre Jülich, Jülich D-52425 (Germany); Misra, R. [Department of Physics and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Schiffer, P. [Department of Physics and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); and others

    2015-06-01

    We investigate the suitability of an epitaxial CaTiO{sub 3} buffer layer deposited onto (100) Si by reactive molecular-beam epitaxy (MBE) for the epitaxial integration of the colossal magnetoresistive material La{sub 0.7}Sr{sub 0.3}MnO{sub 3} with silicon. The magnetic and electrical properties of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} films deposited by MBE on CaTiO{sub 3}-buffered silicon (CaTiO{sub 3}/Si) are compared with those deposited on SrTiO{sub 3}-buffered silicon (SrTiO{sub 3}/Si). In addition to possessing a higher Curie temperature and a higher metal-to-insulator transition temperature, the electrical resistivity and 1/f noise level at 300 K are reduced by a factor of two in the heterostructure with the CaTiO{sub 3} buffer layer. These results are relevant to device applications of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films on silicon substrates.

  7. Ultrathin amorphous zinc-tin-oxide buffer layer for enhancing heterojunction interface quality in metal-oxide solar cells

    OpenAIRE

    Heo, Jaeyeong; Siah, Sin Cheng; Mailoa, Jonathan P.; Brandt, Riley E.; Kim, Sang Bok; Gordon, Roy G.; Buonassisi, Tonio; Lee, Yun seog

    2012-01-01

    We demonstrate a tunable electron-blocking layer to enhance the performance of an Earth-abundant metal-oxide solar-cell material. A 5 nm thick amorphous ternary metal-oxide buffer layer reduces interface recombination, resulting in sizable open-circuit voltage and efficiency enhancements. This work emphasizes the importance of interface engineering in improving the performance of Earth-abundant solar cells.

  8. COATING OF POLYMERIC SUBSTRATE CATALYSTS ON METALLIC SURFACES

    Directory of Open Access Journals (Sweden)

    H. HOSSEINI

    2010-12-01

    Full Text Available This article presents results of a study on coating of a polymeric substrate ca-talyst on metallic surface. Stability of coating on metallic surfaces is a proper specification. Sol-gel technology was used to synthesize adhesion promoters of polysilane compounds that act as a mediator. The intermediate layer was coated by synthesized sulfonated polystyrene-divinylbenzene as a catalyst for production of MTBE in catalytic distillation process. Swelling of catalyst and its separation from the metal surface was improved by i increasing the quantity of divinylbenzene in the resin’s production process and ii applying adhesion pro¬moters based on the sol-gel process. The rate of ethyl silicate hydrolysis was intensified by increasing the concentration of utilized acid while the conden¬sation polymerization was enhanced in the presence of OH–. Sol was formed at pH 2, while the pH should be 8 for the formation of gel. By setting the ratio of the initial concentrations of water to ethyl silicate to 8, the gel formation time was minimized.

  9. Metal oxide films on glass and steel substrates

    CERN Document Server

    Sohi, A M

    1987-01-01

    in the pH8 electrolyte supports the view that the rate limiting reduction reaction is possibly oxygen (or water) reduction although some contribution from an organic 'impurity' cannot be ruled out. Coatings of Fe sub 3 O sub 4 on mild steel have been prepared by CVD using pneumatic spraying techniques and the corrosion behaviour of coated electrodes in organic-phosphate electrolyte (pH8) has been examined. A variety of thin (10-1000nm) metal oxide films have been deposited on flat glass substrates by the pyrolysis of an aerosol of metal acetylacetonates in a suitable carrier. The optical characteristics and thickness of the films have been measured and particular interest has centered on the use of a novel pin on disc apparatus to measure the physical durability of such thin films. Characteristic friction/penetration force traces have been established for 1st Series transition metal oxide films and some ranking in terms of 'hardness' established. The use of SnO sub 2 - coated glass for electrodes in a light m...

  10. Surface-bound iron: a metal ion buffer in the marine brown alga Ectocarpus siliculosus?

    Science.gov (United States)

    Miller, Eric P; Böttger, Lars H; Weerasinghe, Aruna J; Crumbliss, Alvin L; Matzanke, Berthold F; Meyer-Klaucke, Wolfram; Küpper, Frithjof C; Carrano, Carl J

    2014-02-01

    Although the iron uptake and storage mechanisms of terrestrial/higher plants have been well studied, the corresponding systems in marine algae have received far less attention. Studies have shown that while some species of unicellular algae utilize unique mechanisms of iron uptake, many acquire iron through the same general mechanisms as higher plants. In contrast, the iron acquisition strategies of the multicellular macroalgae remain largely unknown. This is especially surprising since many of these organisms represent important ecological and evolutionary niches in the coastal marine environment. It has been well established in both laboratory and environmentally derived samples, that a large amount of iron can be 'non-specifically' adsorbed to the surface of marine algae. While this phenomenon is widely recognized and has prompted the development of experimental protocols to eliminate its contribution to iron uptake studies, its potential biological significance as a concentrated iron source for marine algae is only now being recognized. This study used an interdisciplinary array of techniques to explore the nature of the extensive and powerful iron binding on the surface of both laboratory and environmental samples of the marine brown alga Ectocarpus siliculosus and shows that some of this surface-bound iron is eventually internalized. It is proposed that the surface-binding properties of E. siliculosus allow it to function as a quasibiological metal ion 'buffer', allowing iron uptake under the widely varying external iron concentrations found in coastal marine environments.

  11. Research Progress on Laser Cladding Amorphous Coatings on Metallic Substrates

    Directory of Open Access Journals (Sweden)

    CHEN Ming-hui

    2017-01-01

    Full Text Available The microstructure and property of amorphous alloy as well as the limitations of the traditional manufacturing methods for the bulk amorphous alloy were briefly introduced in this paper.Combined with characteristics of the laser cladding technique,the research status of the laser cladding Fe-based,Zr-based,Ni-based,Cu-based and Al-based amorphous coatings on the metal substrates were mainly summarized.The effects of factors such as laser processing parameter,micro-alloying element type and content and reinforcing phase on the laser cladding amorphous coatings were also involved.Finally,the main problems and the future research directions of the composition design and control of the laser-cladded amorphous coating,the design and optimization of the laser cladding process,and the basic theory of the laser cladding amorphous coatings were also put forward finally.

  12. Crystal structure and polarization hysteresis properties of ferroelectric BaTiO3 thin-film capacitors on (Ba,Sr)TiO3-buffered substrates

    Science.gov (United States)

    Maki, Hisashi; Noguchi, Yuji; Kutsuna, Kazutoshi; Matsuo, Hiroki; Kitanaka, Yuuki; Miyayama, Masaru

    2016-10-01

    Ferroelectric BaTiO3 (BT) thin-film capacitors with a buffer layer of (Ba1- x Sr x )TiO3 (BST) have been fabricated on (001) SrTiO3 (STO) single-crystal substrates by a pulsed laser deposition method, and the crystal structure and polarization hysteresis properties have been investigated. X-ray diffraction reciprocal space mapping shows that the BST buffer effectively reduces the misfit strain relaxation of the BT films on SrRuO3 (SRO) electrodes. The BT capacitor with the SRO electrodes on the BST (x = 0.3) buffer exhibits a well-saturated hysteresis loop with a remanent polarization of 29 µC/cm2. The hysteresis loop displays a shift toward a specific field direction, which is suggested to stem from the flexoelectric coupling between the out-of-plane polarization and the strain gradient adjacent to the bottom interface.

  13. Microscopic mechanisms of graphene electrolytic delamination from metal substrates

    Energy Technology Data Exchange (ETDEWEB)

    Fisichella, G. [CNR-IMM, Strada VIII, 5 – 95121 Catania (Italy); Department of Electronic Engineering, University of Catania, Viale A. Doria, 6 – 95125 Catania (Italy); Di Franco, S.; Roccaforte, F.; Giannazzo, F., E-mail: filippo.giannazzo@imm.cnr.it [CNR-IMM, Strada VIII, 5 – 95121 Catania (Italy); Ravesi, S. [STMicroelectronics, Stradale Primosole, 50 – 95121 Catania (Italy)

    2014-06-09

    In this paper, hydrogen bubbling delamination of graphene (Gr) from copper using a strong electrolyte (KOH) water solution was performed, focusing on the effect of the KOH concentration (C{sub KOH}) on the Gr delamination rate. A factor of ∼10 decrease in the time required for the complete Gr delamination from Cu cathodes with the same geometry was found increasing C{sub KOH} from ∼0.05 M to ∼0.60 M. After transfer of the separated Gr membranes to SiO{sub 2} substrates by a highly reproducible thermo-compression printing method, an accurate atomic force microscopy investigation of the changes in Gr morphology as a function of C{sub KOH} was performed. Supported by these analyses, a microscopic model of the delamination process has been proposed, where a key role is played by graphene wrinkles acting as nucleation sites for H{sub 2} bubbles at the cathode perimeter. With this approach, the H{sub 2} supersaturation generated at the electrode for different electrolyte concentrations was estimated and the inverse dependence of t{sub d} on C{sub KOH} was quantitatively explained. Although developed in the case of Cu, this analysis is generally valid and can be applied to describe the electrolytic delamination of graphene from several metal substrates.

  14. Coatings of metal substrates assisted by laser radiation

    Directory of Open Access Journals (Sweden)

    Caudevilla, H.

    1998-04-01

    Full Text Available In this contribution, a new way of obtaining ceramic coatings is presented. This method uses precursor suspensions, settled on substrates and in-situ pyrolised with a laser. Different deposition techniques of the ceramic precursors have been tested in order to obtain a homogeneous distribution on the metal substrate before the laser treatment.

    La combinación de recubrimientos utilizando disoluciones de precursores metálicos con la pirólisis asistida por láser, permite obtener una gran diversidad de recubrimientos sobre sustratos de muy distinta naturaleza. Se han realizado estudios, tanto con disoluciones poliméricas, como con disoluciones de tipo sol-gel y pastas obtenidas con técnicas similares, depositadas utilizando métodos convencionales de inmersión y atomización previa a la pirólisis asistida por láser, así como simultánea. En este trabajo se presenta un resumen de los resultados más significativos obtenidos en la realización de recubrimientos sobre sustratos metálicos y cerámicos.

  15. ZnO films grown by MOCVD on GaAs substrates: Effects of a Zn buffer deposition on interface, structural and morphological properties

    Science.gov (United States)

    Agouram, S.; Martínez-Tomás, M. C.; Muñoz-Sanjosé, V.

    2009-04-01

    Integration of ZnO with the well-developed GaAs technology presents several aspects that need to be previously analyzed and considered. The large lattice mismatch between ZnO and GaAs and its different crystallographic structure lead to many structural defects. In addition, their potential chemical reactivity is another source of complexity and an academic challenge. Recently some interesting contributions on this subject have been carried out by Liu and co-workers. As an additional step to the knowledge of the ZnO/GaAs heterostructure, we have deepened on the study of the morphology and orientation of ZnO thin films grown by atmospheric pressure metal-organic chemical vapour deposition (AP-MOCVD) on GaAs(1 0 0) and GaAs(1 1 1)A substrates with and without a Zn buffer pre-deposition on them. The analysis has been made as a function of growth temperature and precursors ratio. Structural, morphological and compositional characterizations have been made by X-ray diffraction (XRD), high-resolution X-ray diffraction (HRXRD), scanning electron microscopy (SEM), energy dispersive X-ray microanalysis (EDX) and X-ray photoemission spectroscopy (XPS). ZnO layers present an out-of-plane (0 0 0 1) preferred orientation, while the in-plane orientation has a random distribution. The layers are constituted by large tilted columnar grains with a top angle of around 55° indicating that the planes which constitute the conic heads are the {1 0 1¯ 1} ones. ZnO films grown after a previous Zn deposition exhibit a less compact morphology. In some cases and depending on growth conditions, interfacial processes with crystallization of extrinsic phases have been observed by XRD, revealing the presence of a body centred tetragonal phase of Zn 3As 2. In order to get an insight into these interfacial effects, EDX on cross-sectional views of the interface has been carried out. Strain measurements indicate a tensile nature of the biaxial stress, which is reduced by a factor two when the Zn

  16. Buffer layers for REBCO films for use in superconducting devices

    Science.gov (United States)

    Goyal, Amit; Wee, Sung-Hun

    2014-06-10

    A superconducting article includes a substrate having a biaxially textured surface. A biaxially textured buffer layer, which can be a cap layer, is supported by the substrate. The buffer layer includes a double perovskite of the formula A.sub.2B'B''O.sub.6, where A is rare earth or alkaline earth metal and B' and B'' are different transition metal cations. A biaxially textured superconductor layer is deposited so as to be supported by the buffer layer. A method of making a superconducting article is also disclosed.

  17. Effect of substrate temperatures on evaporated In{sub 2}S{sub 3} thin film buffer layers for Cu(In,Ga)Se{sub 2} solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Zhao Yang; Cho, Eou Sik; Kwon, Sang Jik, E-mail: sjkwon@gachon.ac.kr

    2013-11-29

    For the realization of vacuum in-line process in the fabrication of Cu(In,Ga)Se{sub 2} (CIGS) solar cells, In{sub 2}S{sub 3} thin film buffer layers for CIGS have been deposited on glasses and CIGS layers with a thickness of about 650 Å by thermal evaporation process. During the thermal evaporation, the temperature of the substrate was varied from room temperature to 500 °C by heating and the grown In{sub 2}S{sub 3} films were investigated and analyzed in terms of the optimized buffer layer for CIGS solar cells. From the results of scanning electron microscope and X-ray diffraction, the In{sub 2}S{sub 3} thin film deposited at a higher substrate temperature showed the larger grain size and the films have amorphous structural characteristics. Although the structural characteristics such as the atomic ratio of In to S and transmittance of the In{sub 2}S{sub 3} thin films were not proportional to temperature, it was possible to obtain the large optical band gap of In{sub 2}S{sub 3} films of about 3.8–3.9 eV enough to be used as the buffer layer of CIGS. - Highlights: • In{sub 2}S{sub 3} films were deposited at various substrate temperatures by thermal evaporation. • The atomic ratio of In to S in the In{sub 2}S{sub 3} film has the highest value at 300 °C. • The In{sub 2}S{sub 3} film has a band gap of about 3.8 eV because of its amorphous structure. • The In{sub 2}S{sub 3} film is expected to be used as a buffer layer by in-line vacuum process.

  18. The effects of buffer cations on interactions between mammalian copper-containing amine oxidases and their substrates.

    Science.gov (United States)

    Holt, A; Degenhardt, O S; Berry, P D; Kapty, J S; Mithani, S; Smith, D J; Di Paolo, M L

    2007-01-01

    We and others have observed that substrates for copper-containing amine oxidases cause substrate inhibition at high concentrations. Through use of a novel "pseudoquantitative" rapid equilibrium approach, kinetic analyses with human and bovine enzymes indicate that these effects are consistent with substrates binding to oxidised and reduced enzyme forms. Small cations compete with binding of substrates to oxidised and reduced enzyme, influencing both substrate turnover and substrate inhibition patterns. Cations reduce affinity of the resting bovine enzyme for spermidine, but not benzylamine, indicating that the predominant effect of cations on substrate oxidation results from binding to an anionic site outside the active site. However, binding of cations to the active site of the reduced form of both enzymes attenuates substrate inhibition with both spermidine and benzylamine. Our observations have significant practical implications for researchers assaying kinetic behaviour of these enzymes, and particularly those developing novel inhibitors of human copper-containing amine oxidases.

  19. Buffering the buffer

    Science.gov (United States)

    Leslie M. Reid; Sue Hilton

    1998-01-01

    Riparian buffer strips are a widely accepted tool for helping to sustain aquatic ecosystems and to protect downstream resources and values in forested areas, but controversy persists over how wide a buffer strip is necessary. The physical integrity of stream channels is expected to be sustained if the characteristics and rates of tree fall along buffered reaches are...

  20. Superconducting and structural properties of plasma sprayed YBaCuO layers deposited on metallic substrates

    NARCIS (Netherlands)

    Hemmes, Herman K.; Jäger, D; Smithers, M.A.; Smithers, M.; van der Veer, J.; van der Veer, J.M.; Stover, D.; Rogalla, Horst

    1993-01-01

    The properties of plasma sprayed Y-Ba-Cu-O coatings deposited on metallic substrates are studied. Stainless steel, nickel steels and pure nickel are used as substrate. Y-Ba-Cu-O deposited on stainless steel and nickel steel reacts with the substrate. This interaction can be suppressed by using an

  1. Fabrication of a strain-induced high performance NbN ultrathin film by a Nb5N6 buffer layer on Si substrate

    Science.gov (United States)

    Jia, X. Q.; Kang, L.; Gu, M.; Yang, X. Z.; Chen, C.; Tu, X. C.; Jin, B. B.; Xu, W. W.; Chen, J.; Wu, P. H.

    2014-03-01

    Lattice mismatch between NbN and silicon (Si) reduces the superconducting properties of NbN film on Si substrate, and this in turn affects the performance of devices such as the hot electron bolometer (HEB) and superconducting nanowire single photon detector (SNSPD). We have found that the superconducting properties of NbN film on Si will be significantly improved by a Nb5N6 buffer layer. The strain of the NbN film was optimized by varying the thickness of the buffer layer. With 30 nm thick Nb5N6, the zero resistance superconducting transition temperature (TC0) of a 6 nm thick NbN film on Si is up to 13.5 K and the critical current density (JC) of the film is more than 107 A cm-2. All the details of preparation, improvement and characteristics of this film are also presented.

  2. Cube-textured metal substrates for reel-to-reel processing of coated conductors

    DEFF Research Database (Denmark)

    Wulff, Anders Christian

    This thesis presents the results of a study aimed at investigating important fabrication aspects of reel-to-reel processing of metal substrates for coated conductors and identifying a new substrate candidate material with improved magnetic properties. The eect of mechanical polishing on surface...... texture and the fraction of low angle grain boundaries. Finally, a Ni-5Cu-5W substrate may be a good candidate material as a substrate in future coated conductors....

  3. Aspartate buffer and divalent metal ions affect oxytocin in aqueous solution and protect it from degradation

    DEFF Research Database (Denmark)

    Avanti, Christina; Oktaviani, Nur Alia; Hinrichs, Wouther L.J.

    2013-01-01

    . Furthermore, LC–MS (MS) measurements indicated that the combination of aspartate buffer and Zn2+ in particular suppressed intermolecular degradation reactions near the Cys1,6 disulfide bridge. These results lead to the hypothesis that in aspartate buffer, Zn2+ changes the conformation of oxytocin...... in such a way that the Cys1,6 disulfide bridge is shielded from its environment thereby suppressing intermolecular reactions involving this region of the molecule. To verify this hypothesis, we investigate here the conformation of oxytocin in aspartate buffer in the presence of Mg2+ or Zn2+, using 2D NOESY......, with the largest chemical shift changes observed for Cys1. Zn2+ causes more extensive changes in oxytocin in aqueous solution than Mg2+. Our findings suggest that the carboxylate group of aspartate neutralizes the positive charge of the N-terminus of Cys1, allowing the interactions with Zn2+ to become more...

  4. Charge movement in a GaN-based hetero-structure field effect transistor structure with carbon doped buffer under applied substrate bias

    Energy Technology Data Exchange (ETDEWEB)

    Pooth, Alexander, E-mail: a.pooth@bristol.ac.uk [Center for Device Thermography and Reliability, H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom); IQE (Europe) Ltd., Pascal Close, St. Mellons, Cardiff CF3 0LW (United Kingdom); Uren, Michael J.; Cäsar, Markus; Kuball, Martin [Center for Device Thermography and Reliability, H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom); Martin, Trevor [IQE (Europe) Ltd., Pascal Close, St. Mellons, Cardiff CF3 0LW (United Kingdom)

    2015-12-07

    Charge trapping and transport in the carbon doped GaN buffer of a GaN-based hetero-structure field effect transistor (HFET) has been investigated under both positive and negative substrate bias. Clear evidence of redistribution of charges in the carbon doped region by thermally generated holes is seen, with electron injection and capture observed during positive bias. Excellent agreement is found with simulations. It is shown that these effects are intrinsic to the carbon doped GaN and need to be controlled to provide reliable and efficient GaN-based power HFETs.

  5. Epitaxial Growth of Full-Heusler Alloy Co2MnSi Thin Films on MgO-Buffered MgO Substrates

    OpenAIRE

    Kijima, H; Ishikawa, T.; Marukame, T.; Koyama, H; Matsuda, K; Uemura, T.; Yamamoto, M.

    2006-01-01

    Full-Heusler alloy Co₂MnSi (CMS) thin films were epitaxially grown on MgO-buffered MgO substrates through magnetron sputtering. The films were deposited at room temperature and subsequently annealed in situ at 600℃. X-ray pole figure measurements of the annealed films showed 111 peaks with fourfold symmetry, providing direct evidence that these films were epitaxial and crystallized in the L2₁ structure. The annealed films had sufficiently flat surface morphologies with root-mean-squa...

  6. Hydrothermal epitaxial growth of ZnO films on sapphire substrates presenting epitaxial ZnAl{sub 2}O{sub 4} buffer layers

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hou-Guang, E-mail: houguang@isu.edu.tw; Wang, Chi-Wei; Tu, Zhi-Fan

    2014-03-01

    This article describes our investigation of the hydrothermal epitaxial growth of c-plane ZnO films on Al{sub 2}O{sub 3} substrates presenting ZnAl{sub 2}O{sub 4} buffer layers. We obtained (111) ZnAl{sub 2}O{sub 4} epitaxial layers on a-plane Al{sub 2}O{sub 3} substrates readily through solid phase epitaxy. Although the ZnAl{sub 2}O{sub 4} buffer layers grew epitaxially with a (111) out-of-plane orientation and comprised two coexisting equivalent azimuthal variants with relative 180° in-plane rotation, the ZnO epitaxial films grown upon them exhibited a c-plane orientation with unitary in-plane epitaxial orientation of <11{sup ¯}00>{sub ZnO}∥<11{sup ¯}0>{sub ZnAl{sub 2O{sub 4}}} on the two different ZnAl{sub 2}O{sub 4} variants. Taking the coincidence of the site lattices between the (0001) plane of ZnO and the (111) plane of ZnAl{sub 2}O{sub 4} into account, a reduction in lattice misfit was achieved through a 30° rotation between the lattices of the ZnO and the ZnAl{sub 2}O{sub 4}. We used X-ray diffraction and transmission electron microscopy to obtain detailed microstructural views of the hydrothermally grown ZnO epitaxial films on the ZnAl{sub 2}O{sub 4} buffer layers. - Highlights: • The c-plane ZnO films were epitaxially grown on Al{sub 2}O{sub 3} substrates presenting ZnAl{sub 2}O{sub 4} buffer layers. • We obtained (111) ZnAl{sub 2}O{sub 4} epitaxial layers on a-plane Al{sub 2}O{sub 3} substrates through solid phase epitaxy. • The ZnAl{sub 2}O{sub 4} layers comprised two equivalent azimuthal variants with relative 180° in-plane rotation. • The c-plane ZnO epitaxial films grown on ZnAl{sub 2}O{sub 4} layers with an in-plane relationship of <11{sup ¯}00>{sub ZnO}∥<11{sup ¯}0>{sub ZnAl{sub 2O{sub 4}}}.

  7. Aspartate buffer and divalent metal ions affect oxytocin in aqueous solution and protect it from degradation

    NARCIS (Netherlands)

    Avanti, Christina; Oktaviani, Nur Alia; Hinrichs, Wouter L J; Frijlink, Henderik W; Mulder, Frans A A

    2013-01-01

    Oxytocin is a peptide drug used to induce labor and prevent bleeding after childbirth. Due to its instability, transport and storage of oxytocin formulations under tropical conditions is problematic. In a previous study, we have found that the stability of oxytocin in aspartate buffered formulation

  8. Tuning of the selectivity of fluorescent peptidyl bioprobe using aggregation induced emission for heavy metal ions by buffering agents in 100% aqueous solutions.

    Science.gov (United States)

    Neupane, Lok Nath; Hwang, Gi Won; Lee, Keun-Hyeung

    2017-06-15

    Smart fluorescent probes of which the detection of specific target molecules can be controlled are attracting remarkable interest. A fluorescent peptidyl bioprobe (1) was rationally synthesized by conjugating tetraphenylethylene, an aggregation-induced emission (AIE) fluorophore with a peptide receptor (AspHis) that acted as hard and intermediate bases. The selective detection of 1 for specific metal ion in 100% aqueous solutions was controlled by the buffering agents with the chelate effect without the change of pH. In distilled water and phosphate buffered aqueous solution at neutral pH, 1 exhibited a selective Off-On response to a soft metal ion, Hg 2+ among test metal ions by 100-fold enhancement of the emission at 470nm. 1 showed a selective Off-On response (180-fold enhancement) to a hard metal ion, Al 3+ ions among test metal ions in Tris buffered aqueous solution at neutral pH and Hexamine (hexamethylenetetramine) buffered aqueous solution at acidic pH. The detection limit of 0.46 ppb for Hg 2+ and 2.26 ppb for Al 3+ in each condition was lower than the maximum allowable level of the metal ions in drinking water by EPA. This research helps to understand how buffering agents participate in the complex formation and aggregation of fluorescent probes using an AIE process for the selective detection of specific metal ions in aqueous solutions. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Improving anaerobic digestion of easy-acidification substrates by promoting buffering capacity using biochar derived from vermicompost.

    Science.gov (United States)

    Wang, Dou; Ai, Jing; Shen, Fei; Yang, Gang; Zhang, Yanzong; Deng, Shihuai; Zhang, Jing; Zeng, Yongmei; Song, Chun

    2017-03-01

    Acid-buffering of VCBC and VC was evaluated using 4 VFAs, and their application on anaerobic digestion of CM and KW was investigated. Results indicated acid-buffering capacity of VCBC to acetic, propionic, butyric, and valeric acid was 2.5, 1.1, 1.9 and 1.6-fold higher comparing with VC. CM digestion was not initiated at higher organic loading of 50gTS/kg, while it worked well with 5.0% VCBC or VC. KW was not digested even though VC or VCBC was increased to 15% and 20%. However, KW digestion can be alleviated with increasing VCBC or VC proportion, in which the alleviation by VCBC was better than VC. Average VFAs concentration during CM digestion with VC was 4077.7mg/L comparing with 2835.8mg/L of VCBC, and biogas release was delayed for 10-days accompanying rapid pH decrease in CM digestion with VC, which reflected acid-buffering of biochar played a crucial role on improving anaerobic digestion. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. The coalescence of heterogeneous liquid metal on nano substrate

    Science.gov (United States)

    Wang, Long; Li, Yifan; Zhou, Xuyan; Li, Tao; Li, Hui

    2017-06-01

    Molecular dynamics simulation has been performed to study the asymmetric coalescence of heterogeneous liquid metal on graphene. Simulation results show that the anomalies in the drop coalescence is mainly caused by the wettability of heterogeneous liquid metal. The silver atoms incline to distribute on the outer layer of the gold and copper droplets, revealing that the structure is determined by the interaction between different metal atoms. The coalescence and fusion of heterogeneous liquid metal drop can be predicted by comparing the wettability and the atomic mass of metallic liquid drops, which has important implications in the industrial application such as ink-jet printing and metallurgy.

  11. Ultra-long metal nanowire arrays on solid substrate with strong bonding

    Directory of Open Access Journals (Sweden)

    Chen Lan

    2011-01-01

    Full Text Available Abstract Ultra-long metal nanowire arrays with large circular area up to 25 mm in diameter were obtained by direct electrodeposition on metalized Si and glass substrates via a template-based method. Nanowires with uniform length up to 30 μm were obtained. Combining this deposition process with lithography technology, micrometre-sized patterned metal nanowire array pads were successfully fabricated on a glass substrate. Good adhesion between the patterned nanowire array pads and the substrate was confirmed using scanning acoustic microscopy characterization. A pull-off tensile test showed strong bonding between the nanowires and the substrate. Conducting atomic force microscopy (C-AFM measurements showed that approximately 95% of the nanowires were electrically connected with the substrate, demonstrating its viability to use as high-density interconnect.

  12. Bacterial Exopolysaccharides For Corrosion Inhibition on Metal Substrates

    Science.gov (United States)

    Biofilms, composed of extra-cellular polymers secreted by bacteria, have been observed to both increase as well as decrease the rate of metal corrosion. Exopolysaccharides derived from Leuconostoc mesenteroides cultures have been shown to inhibit corrosion on corrosion-sensitive metals. The substa...

  13. Site-selective metallization of polymeric substrates by the hyperbranched polymer templates

    Energy Technology Data Exchange (ETDEWEB)

    Li, Peiyuan, E-mail: lipearpear@163.com [College of Pharmacy, Guangxi University of Chinese Medicine, Nanning 530001 (China); Yang, Fang [College of Chemistry and Life Science, Guangxi Teachers Education University, Nanning 530001 (China); Li, Xiangcheng [School of Computer, Electronics and Information, Guangxi University, Nanning 530001 (China); He, Chunling [College of Pharmacy, Guangxi University of Chinese Medicine, Nanning 530001 (China); Su, Wei, E-mail: suwmail@163.com [College of Chemistry and Life Science, Guangxi Teachers Education University, Nanning 530001 (China); Chen, Jinhao [College of Chemistry and Life Science, Guangxi Teachers Education University, Nanning 530001 (China); Huo, Lini; Chen, Rui; Lu, Chensheng [College of Pharmacy, Guangxi University of Chinese Medicine, Nanning 530001 (China); Liang, Lifang [College of Chemistry and Life Science, Guangxi Teachers Education University, Nanning 530001 (China)

    2013-09-01

    We demonstrate a simple, cost-effective and universal technique for the fabrication of copper circuit pattern on flexible polymeric substrate. This method relies on a ternary polyethylenimine-poly(acrylic acid)-substrate film incorporating palladium catalysts, which are used as adhesive interlayers for the copper metallization of flexible polymeric substrates. We demonstrated the fabrication of patterned copper films on a variety of flexible polymers with minimum feature sizes of 200 μm. And the resulting copper circuit showed strong adhesion with underlying flexible polymeric substrates. The films were characterized by ATR FT-IR, contact angle, XPS, XRD, TEM and SEM. The direct patterning of metallic circuit on flexible polymeric substrate indicates great potential for the use in electronics industry.

  14. Interfacial Structure and Photocatalytic Activity of Magnetron Sputtered TiO2 on Conducting Metal Substrates

    DEFF Research Database (Denmark)

    Daviðsdóttir, Svava; Petit, Jean-Pierre; Mermoux, Michel

    2014-01-01

    The photocatalytic behavior of magnetron sputtered anatase TiO2 coatings on copper, nickel, and gold was investigated with the aim of understanding the effect of the metallic substrate and coating-substrate interface structure. Stoichiometry and nanoscale structure of the coating were investigated...... using X-ray diffraction, Raman spectroscopy, atomic force microscope, and scanning and transmission electron microscopy. Photocatalytic behavior of the coating was explored by using optical spectrophotometry and electrochemical methods via photovoltage, photocurrent, and scanning kelvin probe microscopy...... measurements. The nature of the metal substrate and coating-substrate interface had profound influence on the photocatalytic behavior. Less photon energy was required for TiO2 excitation on a nickel substrate, whereas TiO2 coating on copper showed a higher band gap attributed to quantum confinement. However...

  15. Lattice pulling effect and strain relaxation in axial (In,Ga)N/GaN nanowire heterostructures grown on GaN-buffered Si(111) substrate

    Energy Technology Data Exchange (ETDEWEB)

    Kong, X.; Trampert, A. [Paul-Drude-Institut fuer Festkoerperelektronik, Hausvogteiplatz 5-7, 10117, Berlin (Germany); Albert, S.; Bengoechea-Encabo, A.; Sanchez-Garcia, M.A.; Calleja, E. [Dpto. Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica, Ciudad Universitaria, 28040, Madrid (Spain)

    2015-04-01

    Transmission electron microscopy and spatially resolved electron energy-loss spectroscopy have been applied to investigate the indium distribution and the interface morphology in axial (In,Ga)N/GaN nanowire heterostructures. The ordered axial (In,Ga)N/GaN nanowire heterostructures with an indium concentration up to 80% are grown by molecular beam epitaxy on GaN-buffered Si(111) substrates. We observed a pronounced lattice pulling effect in all the nanowire samples given in a broad transition region at the interface. The lattice pulling effect becomes smaller and the (In,Ga)N/GaN interface width is reduced as the indium concentration is increased in the (In,Ga)N section. The result can be interpreted in terms of the increased plastic strain relaxation via the generation of the misfit dislocations at the interface. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Virtual GaN substrates via Sc2O3/Y2O3 buffers on Si(111): Transmission electron microscopy characterization of growth defects

    Science.gov (United States)

    Niermann, T.; Zengler, D.; Tarnawska, L.; Stork, P.; Schroeder, T.; Lehmann, M.

    2013-06-01

    The defects and strain of GaN(0001) films as virtual substrate on Si(111) with step-graded Sc2O3(111)/Y2O3(111) buffers were investigated by means of transmission electron microscopy. The misfit dislocation network identified in the interfaces nearly fully compensates the lattice mismatch. Inversion domains and pinholes occur within the closed GaN film. The atomic structure of the inversion domain boundaries is identified. Major parts of the films were found to be N-polar. Threading dislocations were formed as remains from the coalescence of initial GaN islands. Furthermore, the formation of small cubic inclusions is found to be restricted to the vicinity of the interface only.

  17. The effect of metal-buffer bilayer drain/source electrodes on the operational stability of the organic field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Karimi-Alavijeh, H.R., E-mail: h.karimi@eng.ui.ac.ir [Department of Electrical Engineering, University of Isfahan, Isfahan (Iran, Islamic Republic of); Ehsani, A. [Department of Electrical and Avionics Engineering, Malek-Ashtar University of Technology, Isfahan (Iran, Islamic Republic of)

    2015-09-01

    In this paper, we have investigated experimentally the effect of different drain/source (D/S) electrodes and charge injection buffer layers on the electrical properties and operational stability of a stilbene organic field effect transistor (OFET). The results show that the organic buffer layer of copper phthalocyanine (CuPc) considerably improves the electrical properties of the transistors, but has a negligible effect on their temporal behavior. On the other hand, inorganic metal-oxide buffer layer of molybdenum oxide (MoO{sub 3}) drastically changes both the electrical properties and operational stability. The functionalities of this metal-oxide tightly depend on the properties of the D/S metallic electrodes. OFETs with Al/MoO{sub 3} as the bilayer D/S electrodes have the best electrical properties: field effect mobility μ{sub eff} = 0.32 cm{sup 2} V{sup −1} s{sup −1} and threshold voltage V{sub TH} = − 5 V and the transistors with Ag/MoO{sub 3} have the longest operational stability. It was concluded that the chemical stability of the metal/metal-oxide or metal/organic interfaces of the bilayer D/S electrodes determine the operational stability of the OFETs. - Highlights: • The effect of buffer layers on the performance of the stilbene OFETs has been investigated. • Inorganic buffer layer improved the electrical and temporal behaviors simultaneously. • Organic buffer layer only changes the electrical properties. • Chemical stability of the interfaces determines the operational stability of the transistor.

  18. Structure and Thermodynamics of Metal Clusters on Atomically Smooth Substrates.

    Science.gov (United States)

    Eckhoff, M; Schebarchov, D; Wales, D J

    2017-10-23

    We analyze the structure of model NiN and CuN clusters (N = 55, 147) supported on a variety of atomically smooth van der Waals surfaces. The global minima are mapped in the space of two parameters: (i) the laterally averaged surface stickiness, γ, which controls the macroscopic wetting angle, and (ii) the surface microstructure, which produces more subtle but important templating via epitaxial stresses. We find that adjusting the substrate lattice (even at constant γ) can favor different crystal plane orientations in the cluster, stabilize hexagonal close-packed order, or induce various defects, such as stacking faults, twin boundaries, and five-fold disclinations. Thermodynamic analysis reveals substrate-dependent solid-solid transitions in cluster morphology, with tunable transition temperature and sometimes exhibiting re-entrant behavior. These results shed new light on the extent to which a supporting surface can be used to influence the equilibrium behavior of nanoparticles.

  19. Deposition of metal onto a sulfur loaded substrate

    Science.gov (United States)

    Kim, Daeho; Sun, Dezheng; Lu, Wenhao; Chu, Eric; Wyrick, Jon; Cheng, Zhihai; Bartels, Ludwig

    2011-03-01

    A Cu(111) surface can be loaded with sulfur to form a variety of surface patterns. In this work, we study the deposition of copper and molybdenum on a Cu(111) surface and the resultant film morphology as a function of the sulfur pre-loading of the substrate. For copper deposition, we find the formation of adstructures of different geometry depending on the sulfur decoration of the substrate. A 0.143 ML S coverage leads to rectangular structure consisting of 6 lobes while a 0.118 ML S coverage leads to 7 × 7 structure. Notably, annealing allows the sulfur to float up decorating the newly deposited layer. Deposition of molybdenum shows a similar pattern, with ordered MoS2 forming as a result of annealing.

  20. Electrical and piezoelectric properties of BiFeO3 thin films grown on SrxCa1−xRuO3-buffered SrTiO3 substrates

    KAUST Repository

    Yao, Yingbang

    2012-06-01

    (001)-oriented BiFeO 3 (BFO) thin films were grown on Sr xCa 1-xRuO 3- (SCRO; x = 1, 0.67, 0.33, 0) buffered SrTiO 3 (001) substrates using pulsed laser deposition. The microstructural, electrical, ferroelectric, and piezoelectric properties of the thin films were considerably affected by the buffer layers. The interface between the BFO films and the SCRO-buffer layer was found to play a dominant role in determining the electrical and piezoelectric behaviors of the films. We found that films grown on SrRuO 3-buffer layers exhibited minimal electrical leakage while films grown on Sr 0.33Ca 0.67RuO 3-buffer layers had the largest piezoelectric response. The origin of this difference is discussed. © 2012 American Institute of Physics.

  1. Characterization of PZT thin films on metal substrates; Charakterisierung von PZT-Duennschichten auf Metallsubstraten

    Energy Technology Data Exchange (ETDEWEB)

    Dutschke, A.

    2008-02-02

    state due to strong stresses within the films. The magnitude of the lattice distortion is independent of the crystallite size and its extent is generally smaller for crystallites in Nd-doped films than for such in undoped films. After the detailed analysis of the development of the boundary layer between metal substrate and PZT-film, it is identified as a non-ferroelectric, dielectric buffer-layer containing crystalline NiO und NiCr{sub 2}O{sub 4}, different chromium oxides and Pb{sub 2}(CrO{sub 4})O between the PZT film and the conductive substrate significantly diminishing the resulting dielectric properties of the system. By applying a non-stoichiometric La{sub 0,75}Sr{sub 0,2}MnO{sub 3} (ULSM)-electrode below the PZT-film, a better electrical contact is achieved, the (001)-orientation in undoped films is enhanced and narrow P-E-hysteresis loops can be obtained. (orig.)

  2. Effect of N2O-doped buffer layer on the optical properties of ZnO films grown on glass substrates using high-energy H2O generated by catalytic reaction

    Science.gov (United States)

    Kanauchi, Shingo; Ohashi, Yuki; Ohishi, Koichiro; Katagiri, Hironori; Tamayama, Yasuhiro; Kato, Takahiro; Yasui, Kanji

    2016-02-01

    Improvement in the optical properties of ZnO films grown on glass substrates was investigated using a N2O-doped buffer layer inserted between the glass substrate and a ZnO film deposited by chemical vapor deposition (CVD). ZnO films were grown at 773 K using dimethylzinc (DMZn) and high-temperature H2O generated by catalytic reaction as zinc and oxygen sources, respectively. Crystal growth was enhanced for the ZnO film grown on the N2O-doped buffer layer, and the fluctuation in crystal orientation along the c-axis became less than that for a film grown directly on the glass substrate by CVD. The optical transmittance of the film in the wavelength range of 375-700 nm also increased with insertion of the buffer layer.

  3. High temperature coefficient of resistance of low-temperature-grown VO{sub 2} films on TiO{sub 2}-buffered SiO{sub 2}/Si (100) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Miyazaki, Kenichi, E-mail: kenichi-miyazaki@denso.co.jp, E-mail: k.shibuya@aist.go.jp; Suzuki, Megumi; Wado, Hiroyuki [DENSO Corporation, Aichi 470-0111 (Japan); Shibuya, Keisuke, E-mail: kenichi-miyazaki@denso.co.jp, E-mail: k.shibuya@aist.go.jp; Sawa, Akihito [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8562 (Japan)

    2015-08-07

    The introduction of a TiO{sub 2} buffer layer significantly improved the temperature coefficient of resistance (TCR), a measure of the sharpness of the metal–insulator transition, for films of VO{sub 2} grown on SiO{sub 2}/Si (100) substrates at growth temperatures below 670 K. X-ray diffraction and Raman scattering measurements revealed that polycrystalline VO{sub 2} films were formed on the TiO{sub 2}-buffered substrates at low temperatures below 600 K, whereas amorphous films were formed at these temperatures on SiO{sub 2}/Si (100) substrates without a TiO{sub 2} buffer layer. Electron microscopy studies confirmed that the TiO{sub 2} buffer layer enhanced the grain growth of VO{sub 2} films at low growth temperatures. The VO{sub 2} films grown at 600 K on TiO{sub 2}-buffered substrates showed a large TCR of more than 80%/K as a result of the improved crystallinity and grain size of the VO{sub 2} films. Our results provide an effective approach toward the integration of VO{sub 2}-based devices onto Si platforms at process temperatures below 670 K.

  4. Surface and interface of epitaxial CdTe film on CdS buffered van der Waals mica substrate

    Science.gov (United States)

    Yang, Y.-B.; Seewald, L.; Mohanty, Dibyajyoti; Wang, Y.; Zhang, L. H.; Kisslinger, K.; Xie, Weiyu; Shi, J.; Bhat, I.; Zhang, Shengbai; Lu, T.-M.; Wang, G.-C.

    2017-08-01

    Single crystal CdTe films are desirable for optoelectronic device applications. An important strategy of creating films with high crystallinity is through epitaxial growth on a proper single crystal substrate. We report the metalorganic chemical vapor deposition of epitaxial CdTe films on the CdS/mica substrate. The epitaxial CdS film was grown on a mica surface by thermal evaporation. Due to the weak van der Waals forces, epitaxy is achieved despite the very large interface lattice mismatch between CdS and mica (∼21-55%). The surface morphology of mica, CdS and CdTe were quantified by atomic force microscopy. The near surface structures, orientations and texture of CdTe and CdS films were characterized by the unique reflection high-energy electron diffraction surface pole figure technique. The interfaces of CdTe and CdS films and mica were characterized by X-ray pole figure technique and transmission electron microscopy. The out-of-plane and in-plane epitaxy of the heteroepitaxial films stack are determined to be CdTe(111)//CdS(0001)//mica(001) and [ 1 bar2 1 bar]CdTe//[1 bar100]CdS//[010]mica, respectively. The measured photoluminescence (PL), time resolved PL, photoresponse, and Hall mobility of the CdTe/CdS/mica indicate quality films. The use of van der Waals surface to grow epitaxial CdTe/CdS films offers an alternative strategy towards infrared imaging and solar cell applications.

  5. Brazing diamond grits onto a steel substrate using copper alloys as the filler metals

    Science.gov (United States)

    Chen, S.-M.; Lin, S.-T.

    1996-12-01

    Surface-set diamond tools were fabricated by an active metal brazing process, using bronze (Cu-8.9Sn) powder and 316L stainless steel powder mixed to various ratios as the braze filler metals. The diamond grits were brazed onto a steel substrate at 1050 °C for 30 min in a dry hydrogen atmosphere. After brazing practice, an intermediate layer rich in chromium formed between the braze filler metal and diamond. A braze filler metal composed of 70 wt % bronze powder and 30 wt % stainless steel powder was found to be optimum in that the diamond grits were strongly impregnated in the filler metal by both mechanical and chemical types of holding. The diamond tools thus fabricated performed better than conventional nickel-plated diamond tools. In service, the braze filler metal wore at almost the same rate as the diamond grits, and no pullout of diamond grits or peeling of the filler metal layer took place.

  6. A buffer-free method for growth of InAsSb films on GaAs (001) substrates using MOCVD

    Science.gov (United States)

    Ni, Pei-Nan; Tong, Jin-Chao; Tobing, Landobasa Y. M.; Xu, Zheng-Ji; Qiu, Shupeng; Tang, Xiao-Hong; Zhang, Dao-Hua

    2017-06-01

    We report a simple thermal treatment method for direct growth of InAsSb films on GaAs (001) substrates for the first time. The properties of the grown InAsSb films are systematically characterized by scanning electron microscopy, atomic force microscopy, X-ray diffraction, photo-luminescence and Hall measurement. It is found that the grown InAsSb films by this method have high quality with very smooth, mirror-like morphology, good electrical and optical properties. In particular, strong photoluminescence peak at around 3660 nm can be observed even at room temperature, which demonstrates the capabilities of the grown InAsSb films for room temperature MIR optoelectronic application. The mechanism for this growth method is discussed in details. We believe that this work provides a simple and feasible buffer-free strategy for the growth of high quality InAsSb films directly on GaAs substrate and it may also benefit other heteroepitaxial growth.

  7. Orientational control of CeO 2 buffer layers on A-plane sapphire substrates for REBa 2Cu 3O 7-σ thin films

    Science.gov (United States)

    Sakuma, K.; Michikami, O.

    2010-11-01

    We attempted the epitaxial growth of CeO2 on A-plane Al2O3(1 1 2 bar 0) (A-Al2O3) substrates. As a buffer layers, CeO2 layers (CeO2-I) were firstly prepared on A-Al2O3 substrates at room temperature, and crystallized by ex situ annealing. The second CeO2 layers (CeO2-II) were deposited on CeO2-I. The thickness of CeO2-I dependence of the characteristics of CeO2-II and EuBa2Cu3O7-σ (EBCO) thin films, which were deposited on CeO2-II, was investigated. The CeO2-II layer completely was oriented along the c axis, while the in-plane orientation was not perfect. The critical current density (Jc) decreased with degrading the in-plane orientation of EBCO thin films. It is found that the in-plane orientation of EBCO thin films greatly effected on Jc. The best Jc value at 77.3 K of EBCO thin films was 1.9 MA/cm2.

  8. Threading dislocation reduction in three-dimensionally grown GaN islands on Si (111) substrate with AlN/AlGaN buffer layers

    Science.gov (United States)

    Chang, Shane; Lung Wei, Lin; Tung Luong, Tien; Chang, Ching; Chang, Li

    2017-09-01

    Three-dimensional GaN island growth without any masks was first introduced under high pressure in metalorganic chemical vapor deposition after the growth of AlN and AlGaN buffer layers on Si (111) substrate, followed by two-dimensional GaN growth to form a continuous GaN film with improvement of the crystalline quality and surface smoothness. X-ray diffraction and cross-sectional scanning transmission electron microscopy analyses show that a high-quality GaN film can be achieved by bending of edge threading dislocations (TDs) and the formation of dislocation half-loops. It is observed that most of edge TDs bend 90° from the growth direction along c-axis, whereas mixed TDs bend about 30° towards the inclined sidewall facets of the islands. Consequently, a 1.2 μm thick GaN epitaxial film with a low threading dislocation density of 2.5 × 108 cm-2 and a smooth surface of 0. 38 nm roughness can be achieved on Si substrate.

  9. Growth of carbon nanofibers on metal-catalyzed substrates by pulsed laser ablation of graphite

    Energy Technology Data Exchange (ETDEWEB)

    Suda, Y; Tanaka, A; Okita, A; Sakai, Y; Sugawara, H [Graduate School of Information Science and Technology, Hokkaido University, North 14, West 9, Sapporo 060-0814 (Japan)

    2007-04-15

    Carbon nanofibers (CNFs) were grown on metal-catalyzed Si substrates by pulsed laser ablation of graphite. Metal catalysts, Ni, NiCo, Pd and PdNi, were respectively deposited on Si substrates with a SiO{sub 2} layer of 200-nm thickness by a dip coat method, and the substrates placed in a laser oven apparatus. By pulsed laser ablation of graphite for 2 hours, CNFs were grown at oven temperatures {>=} 1000deg. C. Diameters of grown CNFs were about 20-30 nm by scanning electron microscopy, and increased with oven temperature. The difference of CNF growth by the catalysts was shown. Pd-contained catalysts grew thicker CNFs than the other catalysts; while PdNi and NiCo yielded a higher number density of CNFs than the other catalysts. CNF diameter and length changed according to the substrate position from the target. We also discussed the growth mechanism of CNFs with this method.

  10. Direct in Situ Conversion of Metals into Metal-Organic Frameworks: A Strategy for the Rapid Growth of MOF Films on Metal Substrates.

    Science.gov (United States)

    Ji, Hoon; Hwang, Sunhyun; Kim, Keonmok; Kim, CheolGi; Jeong, Nak Cheon

    2016-11-30

    The fabrication of metal-organic framework (MOF) films on conducting substrates has demonstrated great potential in applications such as electronic conduction and sensing. For these applications, direct contact of the film to the conducting substrate without a self-assembled monolayer (SAM) is a desired step that must be achieved prior to the use of MOF films. In this report, we propose an in situ strategy for the rapid one-step conversion of Cu metal into HKUST-1 films on conducting Cu substrates. The Cu substrate acts both as a conducting substrate and a source of Cu 2+ ions during the synthesis of HKUST-1. This synthesis is possible because of the simultaneous reaction of an oxidizing agent and a deprotonating agent, in which the former agent dissolves the metal substrate to form Cu 2+ ions while the latter agent deprotonates the ligand. Using this strategy, the HKUST-1 film could not only be rapidly synthesized within 5 min but also be directly attached to the Cu substrate. Based on microscopic studies, we propose a plausible mechanism for the growth reaction. Furthermore, we show the versatility of this in situ conversion methodology, applying it to ZIF-8, which comprises Zn 2+ ions and imidazole-based ligands. Using an I 2 -filled HKUST-1 film, we further demonstrate that the direct contact of the MOF film to the conducting substrate makes the material more suitable for use as a sensor or electronic conductor.

  11. Topography evolution of rough-surface metallic substrates by solution deposition planarization method

    Science.gov (United States)

    Chu, Jingyuan; Zhao, Yue; Liu, Linfei; Wu, Wei; Zhang, Zhiwei; Hong, Zhiyong; Li, Yijie; Jin, Zhijian

    2018-01-01

    As an emerging technique for surface smoothing, solution deposition planarization (SDP) has recently drawn more attention on the fabrication of the second generation high temperature superconducting (2G-HTS) tapes. In our work, a number of amorphous oxide layers were deposited on electro-polished or mirror-rolled metallic substrates by chemical solution route. Topography evolution of surface defects on these two types of metallic substrates was thoroughly investigated by atomic force microscopy (AFM). It was showed that root mean square roughness values (at 50 × 50 μm2 scanning scale) on both rough substrates reduced to ∼5 nm after coating with SDP-layer. The smoothing effect was mainly attributed to decrease of the depth at grain boundary grooving on the electro-polished metallic substrate. On the mirror-rolled metallic substrates, the amplitude and frequency of the height fluctuation perpendicular to the rolling direction were gradually reduced as depositing more numbers of SDP-layer. A high Jc value of 4.17 MA cm-2 (at 77 K, s.f.) was achieved on a full stack of YBCO/CeO2/IBAD-MgO/SDP-layer/C276 sample. This study enhanced understanding of the topography evolution on the surface defects covered by the SDP-layer, and demonstrated a low-cost route for fabricating IBAD-MgO based YBCO templates with a simplified architecture.

  12. Charge dependent asphaltene adsorption onto metal substrate : electrochemistry and AFM, STM, SAM, SEM analysis

    Energy Technology Data Exchange (ETDEWEB)

    Batina, N.; Morales-Martinez, J. [Univ. Autonoma Metropolitana-Iztapalapa (Mexico). Lab. de Nanotecnologia e Ingenieria Molecular; Ivar-Andersen, S. [Technical Univ. of Denmark (Denmark). Dept. Hem. Eng; Lira-Galeana, C. [Inst. Mexicano del Petroleo, Lazaro (Mexico). Molecular Simulation Research Program; De la Cruz-Hernandez, W.; Cota-Araiza, L.; Avalos-Borja, M. [Univ. Nacional Autonoma de Mexico (Mexico)

    2008-07-01

    Asphaltenes have been identified as the main component of pipeline molecular deposits that cause plugging of oil wells. In this study, Atomic Force Microscopy (AFM), Scanning Tunneling Microscopy (STM), Scanning Auger Microprobe Spectroscopy (SAM) and Scanning Electron Microscopy (SEM) were used to characterized molecular deposits of Mexican crude oil and asphaltenes formed at a charged metal surface. The qualitative and quantitative characterization involved determining the size and shape of adsorbed molecules and aggregates, and the elemental analysis of all components in molecular films. Samples were prepared by electrolytic deposition under galvanostatic or potentiostatic conditions directly from the crude oil or asphaltene in toluene solutions. The study showed that the formation of asphaltene deposit depends on the metal substrate charge. Asphaltenes as well as crude oil readily adsorbed at the negatively charged metal surface. Two elements were present, notably carbon and sulfur. Their content ratio varied depending on the metal substrate charge.

  13. Long-range wetting transparency on top of layered metal-dielectric substrates

    OpenAIRE

    Noginov, M. A.; Yuri A. Barnakov; Vladimir Liberman; Srujana Prayakarao; Bonner, Carl E.; Narimanov, Evgenii E.

    2016-01-01

    It has been recently shown that scores of physical and chemical phenomena (including spontaneous emission, scattering and Förster energy transfer) can be controlled by nonlocal dielectric environments provided by metamaterials with hyperbolic dispersion and simpler metal/dielectric structures. At this time, we have researched van der Waals interactions and experimentally studied wetting of several metallic, dielectric and composite multilayered substrates. We have found that the wetting angle...

  14. Highly textured oxypnictide superconducting thin films on metal substrates

    Energy Technology Data Exchange (ETDEWEB)

    Iida, Kazumasa, E-mail: iida@nuap.nagoya-u.ac.jp; Kurth, Fritz; Grinenko, Vadim; Hänisch, Jens [Institute for Metallic Materials, IFW Dresden, D-01171 Dresden (Germany); Chihara, Masashi; Sumiya, Naoki; Hatano, Takafumi; Ikuta, Hiroshi [Department of Crystalline Materials Science, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Ichinose, Ataru; Tsukada, Ichiro [Central Research Institute of Electric Power Industry, 2-6-1 Nagasaka, Yokosuka, Kanagawa 240-0196 (Japan); Matias, Vladimir [iBeam Materials, Inc., 2778A Agua Fria Street, Santa Fe, New Mexico 87507 (United States); Holzapfel, Bernhard [Institute for Technical Physics, Karlsruhe Institute of Technology, Hermann von Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany)

    2014-10-27

    Highly textured NdFeAs(O,F) thin films have been grown on ion beam assisted deposition-MgO/Y{sub 2}O{sub 3}/Hastelloy substrates by molecular beam epitaxy. The oxypnictide coated conductors showed a superconducting transition temperature (T{sub c}) of 43 K with a self-field critical current density (J{sub c}) of 7.0×10{sup 4} A/cm{sup 2} at 5 K, more than 20 times higher than powder-in-tube processed SmFeAs(O,F) wires. Albeit higher T{sub c} as well as better crystalline quality than Co-doped BaFe{sub 2}As{sub 2} coated conductors, in-field J{sub c} of NdFeAs(O,F) was lower than that of Co-doped BaFe{sub 2}As{sub 2}. These results suggest that grain boundaries in oxypnictides reduce J{sub c} significantly compared to that in Co-doped BaFe{sub 2}As{sub 2} and, hence biaxial texture is necessary for high J{sub c.}.

  15. Investigation of the effects of misfit strain on barium strontium titanate thin films deposited on base metal substrates by a modified phenomenological model

    Science.gov (United States)

    Dong, Hanting; Li, Hongfang; Chen, Jianguo; Jin, Dengren; Cheng, Jinrong

    2017-10-01

    The Landau-Devonshire phenomenological model, which has been utilized to investigate epitaxial barium strontium titanate (BST) thin films, was modified to investigate the effects of misfit strain on the dielectric properties of polycrystalline BST thin films deposited on base metal substrates. The modification considers the relaxation of lattice misfit stress resulting from the formation of in-plane misfit dislocations. The modified lattice misfit strain was calculated by referring to the ferroelectric critical grain size. Moreover, the misfit strain and dielectric properties of BST thin films with different structures and substrates were investigated by the models. It was found that the measured dielectric constant and tunability of BST thin films on different metal substrates overall agreed with the computed data. In addition, the good agreement was also observed for sandwich-like structural BST thin films deposited on LNO buffered stainless steel plates. Our results indicated that the modified L-D models might be utilized to predict dielectric properties of polycrystalline BST thin films for varied substrates and multilayer structures.

  16. Application of a fuzzy logic control system for continuous anaerobic digestion of low buffered, acidic energy crops as mono-substrate.

    Science.gov (United States)

    Scherer, P; Lehmann, K; Schmidt, O; Demirel, B

    2009-02-15

    A fuzzy logic control (FLC) system was developed at the Hamburg University of Applied Sciences (HAW Hamburg) for operation of biogas reactors running on energy crops. Three commercially available measuring parameters, namely pH, the methane (CH4) content, and the specific gas production rate (spec. GPR = m(3)/kg VS/day) were included. The objective was to avoid stabilization of pH with use of buffering supplements, like lime or manure. The developed FLC system can cover most of all applications, such as a careful start-up process and a gentle recovery strategy after a severe reactor failure, also enabling a process with a high organic loading rate (OLR) and a low hydraulic retention time (HRT), that is, a high throughput anaerobic digestion process with a stable pH and CH4 content. A precondition for a high load process was the concept of interval feeding, for example, with 8 h of interval. The FLC system was proved to be reliable during the long term fermentation studies over 3 years in one-stage, completely stirred tank reactors (CSTR) with acidic beet silage as mono-input (pH 3.3-3.4). During fermentation of the fodder beet silage (FBS), a stable HRT of 6.0 days with an OLR of up to 15 kg VS/m(3)/day and a volumetric GPR of 9 m(3)/m(3)/day could be reached. The FLC enabled an automatic recovery of the digester after two induced severe reactor failures. In another attempt to prove the feasibility of the FLC, substrate FBS was changed to sugar beet silage (SBS), which had a substantially lower buffering capacity than that of the FBS. With SBS, the FLC accomplished a stable fermentation at a pH level between 6.5 and 6.6, and a volatile fatty acid level (VFA) below 500 mg/L, but the FLC had to interact and to change the substrate dosage permanently. In a further experiment, the reactor temperature was increased from 41 to 50 degrees C. Concomitantly, the specific GPR, pH and CH4 dropped down. Finally, the FLC automatically enabled a complete recovery in 16 days.

  17. Electrodeposition of metals and magnetic alloys onto conducting polymeric substrates

    Science.gov (United States)

    Leroy, D.; Martinot, L.; Licour, C.; Jérôme, C.; Zhan, H.; Strivay, D.

    1998-06-01

    A new composite material prepared by mixing polycarbonate with carbon black has been tested as new kind of cathode. This material has been compared with a conducting polymer precipitated onto polycarbonate, both in aqueous and organic solutions. We report some examples of electrodeposition of magnetic alloys (Lanthanides/Transition metals) in Formamide. In this medium, the use of thin polypyrrole films cathodes had remained impossible. The preparation of amorphous and magnetic alloys onto PC/carbon black is evidenced by RBS. En préparant un composite conducteur polycarbonate/noir de carbone, nous avons obtenu un nouveau matériau susceptible d'être utilisé comme cathode pour la préparation électrolytique de recouvrements métalliques. Ces cathodes sont comparées à des cathodes de Ppy déposé sur polycarbonate. Nous décrivons ici la réalisation d'alliages magnétiques en couches minces. Ces alliages Lanthanides/Métaux de transition sont préparés en milieu organique (Formamide : FA) où les cathodes constituées de films minces de polypyrrole conducteur ne sont plus utilisables. Le caractère métallique et amorphe de ces alliages est démontré par analyse RBS.

  18. Soldering of Thin Film-Metallized Glass Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Hosking, F.M.; Hernandez, C.L.; Glass, S.J.

    1999-03-31

    The ability to produce reliable electrical and structural interconnections between glass and metals by soldering was investigated. Soldering generally requires premetallization of the glass. As a solderable surface finish over soda-lime-silicate glass, two thin films coatings, Cr-Pd-Au and NiCr-Sn, were evaluated. Solder nettability and joint strengths were determined. Test samples were processed with Sn60-Pb40 solder alloy at a reflow temperature of 210 C. Glass-to-cold rolled steel single lap samples yielded an average shear strength of 12 MPa. Solder fill was good. Control of the Au thickness was critical in minimizing the formation of AuSn{sub 4} intermetallic in the joint, with a resulting joint shear strength of 15 MPa. Similar glass-to-glass specimens with the Cr-Pd-Au finish failed at 16.5 MPa. The NiCr-Sn thin film gave even higher shear strengths of 20-22.5 MPa, with failures primarily in the glass.

  19. Characterization and modeling of the metal diffusion from deep ultraviolet photoresist and silicon-based substrate.

    Science.gov (United States)

    Wang, T K; Wan, M Y; Ko, F H; Tseng, C L

    2001-05-01

    The radioactive tracer technique was applied to investigate the out-diffusion of the transition metals (Cu, Fe and Co) from deep ultraviolet (DUV) photoresist into underlying substrate. Two important process parameters, viz., baking temperatures and substrate types (i.e., bare silicon, polysilicon, silicon oxide and silicon nitride), were evaluated. Results indicate that the out-diffusion of Co is insignificant, irrespective of the substrate type and baking temperature. The out-diffusion of Cu is significant for substrates of bare silicon and polysilicon but not for silicon oxide and nitride; for Fe, the story is reversed. The substrate type appears to strongly affect the diffusion, while the baking temperature does not. Also, the effect of solvent evaporation was found to play an important role in impurity diffusion. Using the method of numerical analysis, a diffusion profile was depicted in this work to describe the out-diffusion of metallic impurities from photoresist layer under various baking conditions. In addition, the effectiveness of various wet-cleaning recipes in removing metallic impurities such as Cu, Fe and Co was also studied using the radioactive tracer technique. Among the six cleaning solutions studied, SC2 and SPM are the most effective in impurity removal. An out-diffusion cleaning model was first proposed to describe the cleaning process. A new cleaning coefficient, h(T), was suggested to explain the cleaning effect. The cleaning model could explain the tracer results.

  20. Thin film pc-Si by aluminium induced crystallization on metallic substrate

    Directory of Open Access Journals (Sweden)

    Cayron C.

    2013-04-01

    Full Text Available Thin film polycrystalline silicon (pc-Si on flexible metallic substrates is promising for low cost production of photovoltaic solar cells. One of the attractive methods to produce pc-Si solar cells consists in thickening a large-grained seed layer by epitaxy. In this work, the deposited seed layer is made by aluminium induced crystallization (AIC of an amorphous silicon (a-Si thin film on metallic substrates (Ni/Fe alloy initially coated with a tantalum nitride (TaN conductive diffusion barrier layer. Effect of the thermal budget on the AIC grown pc-Si seed layer was investigated in order to optimize the process (i.e. the quality of the pc-Si thin film. Structural and optical characterizations were carried out using optical microscopy, μ-Raman and Electron Backscatter Diffraction (EBSD. At optimal thermal annealing conditions, the continuous AIC grown pc-Si thin film showed an average grain size around 15 μm. The grains were preferably (001 oriented which is favorable for its epitaxial thickening. This work proves the feasibility of the AIC method to grow large grains pc-Si seed layer on TaN coated metal substrates. These results are, in terms of grains size, the finest obtained by AIC on metallic substrates.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  3. Materials design considerations involved in the fabrication of implantable bionics by metallization of ceramic substrates.

    Science.gov (United States)

    Patel, Sunil; Guenther, Thomas; Dodds, Christopher W D; Kolke, Sergej; Privat, Karen L; Matteucci, Paul B; Suaning, Gregg J

    2013-01-01

    The Pt metallization of co-fired Al2O3/SiO2 substrates containing Pt feedthroughs was shown to be a suitable means to construct implantable bionics. The use of forge welding to join an electrode to such a metallized feedthrough was demonstrated and subsequently evaluated through the use of metallography and electron microscopy. Metallurgical phenomena involved in forge welding relevant to the fabrication of all types of biomedical implants are discussed within this paper. The affect of thermal profiles used in brazing or welding to build implantable devices from metal components is analysed and the case for considered selection of alloys in implant design is put forward.

  4. Interface science of virtual GaN substrates on Si(111) via Sc2O3/Y2O3 buffers: Experiment and theory

    Science.gov (United States)

    Tarnawska, L.; Dabrowski, J.; Grzela, T.; Lehmann, M.; Niermann, T.; Paszkiewicz, R.; Storck, P.; Schroeder, T.

    2013-06-01

    The final film quality of GaN on foreign substrates is known to crucially depend on the initial GaN interface and nucleation characteristics. To shed light on these characteristics of recently pioneered virtual, hexagonal GaN(0001) substrates on Si(111) via step graded Sc2O3(111)/Y2O3(111) buffers, a complex GaN(0001)/Sc2O3(111) interface structure model and the initial nucleation scenario is derived from a combined experimental (reflection high energy electron diffraction and X-ray photoelectron spectroscopy) and theoretical ab initio study. It is shown that the GaN/Sc2O3 interface chemistry is determined by a N-Ga-O-Sc atomic arrangement leading to N-polar GaN films. However, the atomic GaN(0001)/Sc2O3(111) interface configuration is complex and local perturbations might be at the origin of Ga-polar inversion domains in the mainly N-polar GaN films. The initial growth of GaN on Sc2O3 is characterized by an ultrathin N-Ga-O-Sc wetting layer which carries tensile strain and relaxes with increasing thickness. Further GaN deposition results in the formation of 3D islands which fully relax before island coalescence occurs. The implications of the GaN/Sc2O3 interface configuration, the 3D nucleation growth mode, and the coalescence process of misaligned islands are discussed with respect to the defect characteristics (inversion domains, cubic inclusions, threading dislocations) of the final GaN layer.

  5. Solution processed transition metal oxide anode buffer layers for efficiency and stability enhancement of polymer solar cells

    Science.gov (United States)

    Ameen, M. Yoosuf; Shamjid, P.; Abhijith, T.; Reddy, V. S.

    2018-01-01

    Polymer solar cells were fabricated with solution-processed transition metal oxides, MoO3 and V2O5 as anode buffer layers (ABLs). The optimized device with V2O5 ABL exhibited considerably higher power conversion efficiency (PCE) compared to the devices based on MoO3 and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) ABLs. The space charge limited current measurements and impedance spectroscopy results of hole-only devices revealed that V2O5 provided a very low charge transfer resistance and high hole mobility, facilitating efficient hole transfer from the active layer to the ITO anode. More importantly, incorporation of V2O5 as ABL resulted in substantial improvement in device stability compared to MoO3 and PEDOT:PSS based devices. Unencapsulated PEDOT:PSS-based devices stored at a relative humidity of 45% have shown complete failure within 96 h. Whereas, MoO3 and V2O5 based devices stored in similar conditions retained 22% and 80% of their initial PCEs after 96 h. Significantly higher stability of the V2O5-based device is ascribed to the reduction in degradation of the anode/active layer interface, as evident from the electrical measurements.

  6. Low-Temperature in Situ Growth of Graphene on Metallic Substrates and Its Application in Anticorrosion.

    Science.gov (United States)

    Zhu, Minmin; Du, Zehui; Yin, Zongyou; Zhou, Wenwen; Liu, Zhengdong; Tsang, Siu Hon; Teo, Edwin Hang Tong

    2016-01-13

    Metal or alloy corrosion brings about huge economic cost annually, which is becoming one area of growing concern in various industries, being in bulk state or nanoscale range. Here, single layer or few layers of graphene are deposited on various metallic substrates directly at a low temperature down to 400 °C. These substrates can be varied from hundreds-micrometer bulk metallic or alloy foils to tens of nanometer nanofibers (NFs). Corrosion analysis reveals that both graphene-grown steel sheets and NFs have reduced the corrosion rate of up to ten times lower than that of their bare corresponding counterparts. Moreover, such low-temperature in situ growth of graphene demonstrates stable and long-lasting anticorrosion after long-term immersion. This new class of graphene coated nanomaterials shows high potentials in anticorrosion applications for submarines, oil tankers/pipelines, and ruggedized electronics.

  7. Calcium and Zinc Containing Bactericidal Glass Coatings for Biomedical Metallic Substrates

    Directory of Open Access Journals (Sweden)

    Leticia Esteban-Tejeda

    2014-07-01

    Full Text Available The present work presents new bactericidal coatings, based on two families of non-toxic, antimicrobial glasses belonging to B2O3–SiO2–Na2O–ZnO and SiO2–Na2O–Al2O3–CaO–B2O3 systems. Free of cracking, single layer direct coatings on different biomedical metallic substrates (titanium alloy, Nb, Ta, and stainless steel have been developed. Thermal expansion mismatch was adjusted by changing glass composition of the glass type, as well as the firing atmosphere (air or Ar according to the biomedical metallic substrates. Formation of bubbles in some of the glassy coatings has been rationalized considering the reactions that take place at the different metal/coating interfaces. All the obtained coatings were proven to be strongly antibacterial versus Escherichia coli (>4 log.

  8. Magnetic properties of transition-metal nanoclusters on a biological substrate

    Science.gov (United States)

    Herrmannsdöerfer, T.; Bianchi, A. D.; Papageorgiou, T. P.; Pobell, F.; Wosnitza, J.; Pollmann, K.; Merroun, M.; Raff, J.; Selenska-Pobell, S.

    We have investigated the magnetic properties of transition-metal clusters with a single grain size of about 1 nm. These metallic nanoclusters have been deposed on a biological substrate. This substrate is a purified self-assembling paracrystalline surface layer (S-layer) of the Bacillus sphaericus strain JG-A12, which exhibits square symmetry and is composed of identical protein monomers. First data of the magnetic susceptibility, taken in a SQUID magnetometer at 0< B<7 T and 1.8 K< T<400 K, reveal unusual magnetic properties. The Stoner enhancement factor of the d conduction-electron susceptibility in the Pd and Pt nanoclusters is dramatically reduced compared to the one of the corresponding bulk transition metals. The weakened magnetism of the 5d electrons is considered to play a crucial role for the occurrence of superconductivity in microgranular Pt by adjusting the balance between electron-phonon interactions and competing magnetic interactions.

  9. Magnetic properties of transition-metal nanoclusters on a biological substrate

    Energy Technology Data Exchange (ETDEWEB)

    Herrmannsdoeerfer, T. [Institut Hochfeld-Magnetlabor Dresden (HLD), Forschungszentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany)]. E-mail: T.Herrmannsdoerfer@fz-rossendorf.de; Bianchi, A.D. [Institut Hochfeld-Magnetlabor Dresden (HLD), Forschungszentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany); Papageorgiou, T.P. [Institut Hochfeld-Magnetlabor Dresden (HLD), Forschungszentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany); Pobell, F. [Institut Hochfeld-Magnetlabor Dresden (HLD), Forschungszentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany); Wosnitza, J. [Institut Hochfeld-Magnetlabor Dresden (HLD), Forschungszentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany); Pollmann, K. [Institut fuer Radiochemie, Forschungszentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany); Merroun, M. [Institut fuer Radiochemie, Forschungszentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany); Raff, J. [Institut fuer Radiochemie, Forschungszentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany); Selenska-Pobell, S. [Institut fuer Radiochemie, Forschungszentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany)

    2007-03-15

    We have investigated the magnetic properties of transition-metal clusters with a single grain size of about 1 nm. These metallic nanoclusters have been deposed on a biological substrate. This substrate is a purified self-assembling paracrystalline surface layer (S-layer) of the Bacillus sphaericus strain JG-A12, which exhibits square symmetry and is composed of identical protein monomers. First data of the magnetic susceptibility, taken in a SQUID magnetometer at 0metals. The weakened magnetism of the 5d electrons is considered to play a crucial role for the occurrence of superconductivity in microgranular Pt by adjusting the balance between electron-phonon interactions and competing magnetic interactions.

  10. Malic enzyme: Tritium isotope effects with alternative dinucleotide substrates and divalent metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Karsten, W.E.; Harris, B.G.; Cook, P.F. (Texas College of Osteopathic Medicine, Fort Worth (United States))

    1992-01-01

    The NAD-malic enzyme from Ascaris suum catalyzes the divalent metal ion dependent oxidative decarboxylation of L-malate to yield pyruvate, carbon dioxide and NADH. Multiple isotope effect studies suggest a stepwise chemical mechanism with hydride transfer from L-malate to NAD occurring first to form oxalacetate, followed by decarboxylation. Utilizing L-malate-2-T, tritium V/K isotope effects have been determined for the hydride transfer step using a variety of alternative dinucleotide substrates and divalent metal ions. Combination of these data with deuterium isotope effects data and previously determined [sup 13]C isotope effects has allowed the calculation of intrinsic isotope effects for the malic enzyme catalyzed reaction. The identity of both the dinucleotide substrate and divalent metal ion has an effect of the size of the intrinsic isotope effect for hydride transfer.

  11. Comparison of different grading schemes in InGaAs metamorphic buffers on GaAs substrate: Tilt dependence on cross-hatch irregularities

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rahul, E-mail: rkp203@gmail.com [Advanced Technology Development Centre, Indian Institute of Technology, Kharagpur 721302 (India); Bag, Ankush [Advanced Technology Development Centre, Indian Institute of Technology, Kharagpur 721302 (India); Mukhopadhyay, Partha [Rajendra Mishra School of Engineering Entrepreneurship, Indian Institute of Technology, Kharagpur 721302 (India); Das, Subhashis [Advanced Technology Development Centre, Indian Institute of Technology, Kharagpur 721302 (India); Biswas, Dhrubes [Department of Electronics & Electrical Communication Engineering, Indian Institute of Technology, Kharagpur 721 302 (India)

    2015-12-01

    Highlights: • InGaAs graded MBs with different grading scheme has been grown by MBE on GaAs. • Continuously graded MB exhibits smoother surface morphology. • Grading scheme has been found to have little impact on lattice relaxation. • Grading schemeaffects the lattice tilt significantly. • Cross-hatch surface irregularities affect the crystallographic tilt. - Abstract: InGaAs graded metamorphic buffers (MBs) with different grading strategies have been grown by molecular beam epitaxy (MBE) on GaAs (0 0 1) substrate. A detailed comparative analysis of surface using atomic force microscopy (AFM), and bulk properties using high resolution X-ray diffraction (HRXRD) and room temperature photoluminescence (RTPL) of grown MBs have been presented to comprehend the effectiveness of different grading scheme on InGaAs MBs. Conventional, statistical and fractal analysis on measured AFM data has been performed for in-depth investigation of these surfaces. The grading scheme has been found to have little impact on residual strain while it affects the epitaxial tilt significantly. Moreover, the tilt has been found to depend on growth front irregularities. Tilt magnitude in a graded MB has been found to vary with composition while tilt azimuth has been found to be almost same in the graded layers. PL Intensity and a shift in the PL peaks have been used to study the quality of the MB and residual strain comparatively.

  12. Performance of a continuous flow microbial reverse-electrodialysis electrolysis cell using a non-buffered substrate and catholyte effluent addition.

    Science.gov (United States)

    Hidayat, Syarif; Song, Young-Hyun; Park, Joo-Yang

    2017-09-01

    A continuous flow microbial reverse-electrodialysis electrolysis cell (MREC) was operated under non-buffered substrate with various flow rates of catholyte effluent into anode chamber to investigate the effects on the hydrogen gas production. Adding the catholyte effluent to the anolyte influent resulted in increased salt concentration in the anolyte influent. The increasing anolyte influent salt concentration to 0.23M resulted in improved hydrogen gas production, Coulombic recovery, yield, and hydrogen production rate to 25±1.4mL, 83±5%, 1.49±0.15mol-H2/mole-COD, 0.91±0.03m3-H2/m3-Van/day, respectively. These improvements were attributed to the neutral pH rather than increase in anolyte conductivity as there was no significant improvement in the reactor performance when the NaCl was directly added to the reactor. These results show that addition of catholyte effluent into the anode chamber improved the MREC performance. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Alkylamine capped metal nanoparticle "inks" for printable SERS substrates, electronics and broadband photodetectors.

    Science.gov (United States)

    Polavarapu, Lakshminarayana; Manga, Kiran Kumar; Yu, Kuai; Ang, Priscilla Kailian; Cao, Hanh Duyen; Balapanuru, Janardhan; Loh, Kian Ping; Xu, Qing-Hua

    2011-05-01

    We report a facile and general method for the preparation of alkylamine capped metal (Au and Ag) nanoparticle "ink" with high solubility. Using these metal nanoparticle "inks", we have demonstrated their applications for large scale fabrication of highly efficient surface enhanced Raman scattering (SERS) substrates by a facile solution processing method. These SERS substrates can detect analytes down to a few nM. The flexible plastic SERS substrates have also been demonstrated. The annealing temperature dependent conductivity of the nanoparticle films indicated a transition temperature above which high conductivity was achieved. The transition temperature could be tailored to the plastic compatible temperatures by using proper alkylamine as the capping agent. The ultrafast electron relaxation studies of the nanoparticle films demonstrated that faster electron relaxation was observed at higher annealing temperatures due to stronger electronic coupling between the nanoparticles. The applications of these highly concentrated alkylamine capped metal nanoparticle inks for the printable electronics were demonstrated by printing the oleylamine capped gold nanoparticles ink as source and drain for the graphene field effect transistor. Furthermore, the broadband photoresponse properties of the Au and Ag nanoparticle films have been demonstrated by using visible and near-infrared lasers. These investigations demonstrate that these nanoparticle "inks" are promising for applications in printable SERS substrates, electronics, and broadband photoresponse devices. © The Royal Society of Chemistry 2011

  14. Effects of sputtered buffer layer on the characteristics of ZnO:Al films grown on glass substrates using high-temperature H2O generated by a catalytic reaction

    Science.gov (United States)

    Nishiyama, Tomoya; Takezawa, Kazuki; Nakazawa, Yuta; Oyanagi, Takahiro; Kato, Takahiro; Oishi, Koichiro; Nakamura, Susumu; Yasui, Kanji

    2014-02-01

    The improvement in the quality of ZnO:Al films grown on glass substrates was investigated using a sputtered buffer layer inserted between a glass substrate and a ZnO:Al CVD film. ZnO:Al layers were grown at 773 K using dimethylzinc (DMZn), trimethylaluminum (TMAl), and high-temperature H2O generated by a catalytic reaction as zinc, aluminum, and oxygen sources, respectively. The electron mobility increased by approximately 20 cm2 V-1 s-1 with the use of a buffer layer with a thickness of approximately 40 nm. In addition, the optical transmittance in the wavelength range of 380-600 nm increased with the insertion of the buffer layer. For the growth of ZnO films on a sputtered buffer layer, the average surface roughness was reduced, and as a result the fluctuation in crystal orientation along the c-axis became smaller than that of the film grown directly on the glass substrate by the proposed CVD. This resulted in improvements in the optical transmittance and electron mobility of the ZnO:Al films.

  15. Microstructure of planar glass substrates modified by Laser Ablation Backwriting (LAB) of metal targets

    Energy Technology Data Exchange (ETDEWEB)

    Rey-García, F. [UA Microóptica and Óptica GRIN, Departamento de Física Aplicada, Facultade de Óptica e Optometría, Universidade de Santiago de Compostela, Campus Vida s/n, E-15782 Santiago de Compostela (Spain); Instituto de Ciencia de Materiales de Aragón (CSIC-Universidad de Zaragoza), María de Luna 3, E-50018 Zaragoza (Spain); Flores-Arias, M.T.; Gómez-Reino, C. [UA Microóptica and Óptica GRIN, Departamento de Física Aplicada, Facultade de Óptica e Optometría, Universidade de Santiago de Compostela, Campus Vida s/n, E-15782 Santiago de Compostela (Spain); Lahoz, R. [Instituto de Ciencia de Materiales de Aragón (CSIC-Universidad de Zaragoza), María de Luna 3, E-50018 Zaragoza (Spain); Fuente, G.F. de la, E-mail: xerman@unizar.es [Instituto de Ciencia de Materiales de Aragón (CSIC-Universidad de Zaragoza), María de Luna 3, E-50018 Zaragoza (Spain); Assenmacher, W.; Mader, W. [Institut für Anorganische Chemie, Universität Bonn, Romerstrasse 164, D-53117 Bonn (Germany)

    2014-07-01

    Geometrically controlled, channel-like structures were prepared on commercial, soda-lime glass substrates, by a Laser Ablation Backwriting (LAB) process using a commercial Nd:YVO{sub 4} laser fitted with a beam steering galvanometer mirror unit. 70Cu30Zn Brass alloy, Ag and Al metal targets were evaporated onto glass substrates by simple irradiation through the same glass substrates. The resultant structures were characterized by SEM, TEM, and UV-vis-nIR spectroscopy. These revealed the presence of metal nanostructures in the case of brass and Ag targets, with their typical local surface plasmon resonance (LSPR) bands. In contrast, Al was not found in its elemental form, but rather integrated into the glass substrate. These results were confirmed by energy dispersive X-ray microanalysis (EDS) studies, performed with TEM and SEM observation on representative, polished cross section samples. Preliminary light guiding studies demonstrated the potential to develop burried waveguides just below the surface of the glass substrates in all cases, suggesting that LAB may be a convenient method to prepare stable waveguides by modifying inexpensive, commercial window glass.

  16. Substrate-Independent Epitaxial Growth of the Metal-Organic Framework MOF-508a.

    Science.gov (United States)

    Wilson, M; Barrientos-Palomo, S N; Stevens, P C; Mitchell, N L; Oswald, G; Nagaraja, C M; Badyal, J P S

    2018-01-31

    Plasmachemical deposition is a substrate-independent method for the conformal surface functionalization of solid substrates. Structurally well-defined pulsed plasma deposited poly(1-allylimidazole) layers provide surface imidazole linker groups for the directed liquid-phase epitaxial (layer-by-layer) growth of metal-organic frameworks (MOFs) at room temperature. For the case of microporous [Zn (benzene-1,4-dicarboxylate)-(4,4'-bipyridine) 0.5 ] (MOF-508), the MOF-508a polymorph containing two interpenetrating crystal lattice frameworks undergoes orientated Volmer-Weber growth and displays CO 2 gas capture behavior at atmospheric concentrations in proportion to the number of epitaxially grown MOF-508 layers.

  17. Growth of InAs Quantum Dots on Germanium Substrate Using Metal Organic Chemical Vapor Deposition Technique

    Directory of Open Access Journals (Sweden)

    Tyagi Renu

    2009-01-01

    Full Text Available Abstract Self-assembled InAs quantum dots (QDs were grown on germanium substrates by metal organic chemical vapor deposition technique. Effects of growth temperature and InAs coverage on the size, density, and height of quantum dots were investigated. Growth temperature was varied from 400 to 450 °C and InAs coverage was varied between 1.40 and 2.35 monolayers (MLs. The surface morphology and structural characteristics of the quantum dots analyzed by atomic force microscope revealed that the density of the InAs quantum dots first increased and then decreased with the amount of InAs coverage; whereas density decreased with increase in growth temperature. It was observed that the size and height of InAs quantum dots increased with increase in both temperature and InAs coverage. The density of QDs was effectively controlled by growth temperature and InAs coverage on GaAs buffer layer.

  18. Non-invasively improving the Schottky barriers of metal-MoS2 interfaces: effects of atomic vacancies in a BN buffer layer.

    Science.gov (United States)

    Su, Jie; Feng, Liping; Liu, Siyang; Liu, Zhengtang

    2017-08-09

    Using first-principles calculations within density functional theory, vacancies in the BN buffer layer have been predicted to improve the Schottky barrier of the metal-MoS2 interface without deteriorating the intrinsic properties of the MoS2 layer. Here, the effects of concentrations, sizes and types of vacancies on the contact properties of metal/BN-MoS2 sandwich interfaces are comparatively studied. The results show that vacancies in the BN buffer layer not only don't deteriorate the charge scatterings and electronic properties of the MoS2 layer at the metal/BN-MoS2 interface, but also improve the charge density and contact resistance between the metal surface and the BN layer. Although these vacancies have a negligible influence on the Fermi level pinning effect of the metal/BN-MoS2 interface, both N-vacancies and B-vacancies significantly change the position of the Fermi level of the metal/BN-MoS2 interface and then tune the Schottky barriers. Moreover, the Schottky barriers of metal/BN-MoS2 interfaces can decrease at first with the increasing concentrations and sizes of vacancies. When the concentration of vacancies increases to 4%, the Schottky barriers of metal/BN-MoS2 interfaces can reduce to the minimum value. The lowest n-type and p-type Schottky barriers of Au/BN-MoS2 and Pt/BN-MoS2 interfaces can reduce to -0.16 and 0.28 eV, respectively. However, the Schottky barriers are deteriorated when the sizes and concentrations of vacancies continue to increase because vacancies with large sizes and concentrations obviously change the interfacial structures of metal/BN-MoS2 interfaces and disarrange the directions of interface dipoles. The predictions in this work provide a non-invasive method to achieve high performance metal-MoS2 interfaces with low Schottky barriers.

  19. Adlayer Core-Level Shifts of Random Metal Overlayers on Transition-Metal Substrates

    DEFF Research Database (Denmark)

    Ganduglia-Pirovano, M. V.; Kudrnovský, J.; Scheffler, M.

    1997-01-01

    and the screening effects induced by the core hole, and study the influence of the alloy composition for a number of noble metal-transition metal systems. Our analysis clearly indicates the importance of final-state screening effects for the interpretation of measured core-level shifts. Calculated deviations from...... the initial-state trends are explained in terms of the change of inter- and intra-atomic screening upon alloying. A possible role of alloying on the chemical reactivity of metal surfaces is discussed....

  20. Transfer-Free Electrical Insulation of Epitaxial Graphene from its Metal Substrate

    DEFF Research Database (Denmark)

    Lizzit, Silvano; Larciprete, Rosanna; Lacovig, Paolo

    2012-01-01

    High-quality, large-area epitaxial graphene can be grown on metal surfaces, but its transport properties cannot be exploited because the electrical conduction is dominated by the substrate. Here we insulate epitaxial graphene on Ru(0001) by a stepwise intercalation of silicon and oxygen......, and the eventual formation of a SiO2 layer between the graphene and the metal. We follow the reaction steps by X-ray photoemission spectroscopy and demonstrate the electrical insulation using a nanoscale multipoint probe technique....

  1. In situ sputter cleaning of thin film metal substrates for UHV-TEM corrosion studies.

    Science.gov (United States)

    Heinemann, K.; Poppa, H.

    1973-01-01

    A prerequisite for conducting valid corrosion experiments by in situ electron microscopy techniques is not only the achievement of UHV background pressure conditions at the site of the specimen but also the ability to clean the surface of the thin metal substrate specimen before initiation of the corrosive interaction. A miniaturized simple ion gun has been constructed for this purpose. The gun is small enough to be incorporated into an UHV electron microscope specimen chamber with hot stage in such a way as to permit bombardment of the substrate specimen while observing it by transmission electron microscopy TEM. It is shown that the ion beam generated is confined well enough to cause a sputtering removal of substrate material at a rate of approximately 5-10 A/min and to prevent the sputter deposition of contaminating material from the specimen holder.

  2. Fully solution-processed organic solar cells on metal foil substrates

    KAUST Repository

    Gaynor, Whitney

    2009-08-19

    We demonstrate fully solution-processed organic photovoltaic cells on metal foil substrates with power conversion efficiencies similar to those obtained in devices on transparent substrates. The cells are based on the regioregular poly- (3-hexylthiophene) and C61 butyric acid methyl ester bulk heterojunction system. The bottom electrode is a silver film whose workfunction is lowered by Cs2CO3 using spin-coating to serve as a cathode. The transparent top anode consists of a conductive polymer in combination with a solution-processed silver nanowire mesh that is laminated onto the devices. Each layer of the device, including the transparent electrode, is fabricated from solution, giving rise to the possibility of completely printed solar cells on low-cost substrates.

  3. Substrate Effect on Optical Properties of Insulator-Metal Transition in VO2 Thin Films

    OpenAIRE

    Radue, E.; Crisman, E.; L. Wang; Kittiwatanakul, S.; Lu, J.; Wolf, S. A.; Wincheski, R.; Lukaszew, R. A.; Novikova, I.

    2012-01-01

    In this paper we used Raman spectroscopy to investigate the optical properties of vanadium dioxide (VO2) thin films during the thermally induced insulating to metallic phase transition. We observed a significant difference in transition temperature in similar VO2 films grown on quartz and sapphire substrates: the film grown on quartz displayed the phase transition at a lower temperature (Tc=50C) compared a film grown on sapphire (Tc=68C). We also investigated differences in the detected Raman...

  4. Synthesis and characterization of ZnO nanostructures on noble-metal coated substrates

    Energy Technology Data Exchange (ETDEWEB)

    Dikovska, A.Og. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, Sofia 1784 (Bulgaria); Atanasova, G.B. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 11, 1113 Sofia (Bulgaria); Avdeev, G.V. [Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 11, 1113 Sofia (Bulgaria); Nedyalkov, N.N. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, Sofia 1784 (Bulgaria)

    2016-06-30

    Highlights: • ZnO nanostructures were fabricated on Au–Ag alloy coated silicon substrates by applying pulsed laser deposition. • Morphology of the ZnO nanostructures was related to the Au–Ag alloy content in the catalyst layer. • Increasing the Ag content in Au–Ag catalyst layer changes the morphology of the ZnO nanostructures from nanorods to nanobelts. - Abstract: In this work, ZnO nanostructures were fabricated on noble-metal (Au, Ag and Au–Ag alloys) coated silicon substrates by applying pulsed laser deposition. The samples were prepared at a substrate temperature of 550 °C, an oxygen pressure of 5 Pa, and a laser fluence of 2 J cm{sup −2} – process parameters usually used for deposition of smooth and dense thin films. The metal layer's role is substantial for the preparation of nanostructures. Heating of the substrate changed the morphology of the metal layer and, subsequently, nanoparticles were formed. The use of different metal particles resulted in different morphologies and properties of the ZnO nanostructures synthesized. The morphology of the ZnO nanostructures was related to the Au–Ag alloy's content of the catalyst layer. It was found that the morphology of the ZnO nanostructures evolved from nanorods to nanobelts as the ratio of Au/Ag in the alloy catalyst was varied. The use of a small quantity of Ag in the Au–Ag catalyst (Au{sub 3}Ag) layer resulted predominantly in the deposition of ZnO nanorods. A higher Ag content in the catalyst alloy (AuAg{sub 2}) layer resulted in the growth of a dense structure of ZnO nanobelts.

  5. Femtosecond laser absorption, heat propagation, and damage threshold analysis for Au coating on metallic substrates

    Science.gov (United States)

    Suslova, Anastassiya; Hassanein, Ahmed

    2017-11-01

    The role of metallic substrates as a heat sink for thin layer gold coatings in double-layered optical components exposed to the ultrashort pulsed laser was investigated with the focus on the impact of the gold layer thickness. A two dimensional FEMTO-2D computational code for solid metallic targets with two-layered assemblies has been developed. The model is then used to simulate targets response to fs laser pulses at near damage threshold fluence and to determine the target damage threshold depending on its structure and the substrate material. Considering temperature dependent optical properties of a gold allowed us to make quantitative estimation of the damage threshold unlike many other models. The simulations show decreasing heat sink effect of the substrate with increasing coating thickness until it becomes negligible for 200 nm gold layer. Preliminary results show that a maximum improvement of the damage threshold of about 10% compared to a pure gold target is predicted for 50 nm gold coatings on two substrate materials: copper and nickel.

  6. Selective-area growth and controlled substrate coupling of transition metal dichalcogenides

    Science.gov (United States)

    Bersch, Brian M.; Eichfeld, Sarah M.; Lin, Yu-Chuan; Zhang, Kehao; Bhimanapati, Ganesh R.; Piasecki, Aleksander F.; Labella, Michael, III; Robinson, Joshua A.

    2017-06-01

    Developing a means for true bottom-up, selective-area growth of two-dimensional (2D) materials on device-ready substrates will enable synthesis in regions only where they are needed. Here, we demonstrate seed-free, site-specific nucleation of transition metal dichalcogenides (TMDs) with precise control over lateral growth by utilizing an ultra-thin polymeric surface functionalization capable of precluding nucleation and growth. This polymer functional layer (PFL) is derived from conventional photoresists and lithographic processing, and is compatible with multiple growth techniques, precursors (metal organics, solid-source) and TMDs. Additionally, we demonstrate that the substrate can play a major role in TMD transport properties. With proper TMD/substrate decoupling, top-gated field-effect transistors (FETs) fabricated with selectively-grown monolayer MoS2 channels are competitive with current reported MoS2 FETs. The work presented here demonstrates that substrate surface engineering is key to realizing precisely located and geometrically-defined 2D layers via unseeded chemical vapor deposition techniques.

  7. Development of 1 m HTS conductor using YBCO on textured metal substrate

    Energy Technology Data Exchange (ETDEWEB)

    Yagi, M., E-mail: m-yagi@ch.furukawa.co.j [Furukawa Electric Co., Ltd, 6, Yawata-Kaigandori, Ichihara, Chiba 290-8555 (Japan); Sakamoto, H. [Furukawa Electric Co., Ltd, 500, Kiyotaki-machi, Nikko, Tochigi 321-1493 (Japan); Mukoyama, S. [Furukawa Electric Co., Ltd, 6, Yawata-Kaigandori, Ichihara, Chiba 290-8555 (Japan); Yamamoto, K. [Furukawa Electric Co., Ltd, 500, Kiyotaki-machi, Nikko, Tochigi 321-1493 (Japan); Amemiya, N. [Kyoto University, Kyotodaigaku-Katsura, Nishikyo, Kyoto 615-8510 (Japan); Nagaya, S.; Kashima, N. [Chubu Electric Power Co., Inc., 20-1, Kitasekiyama, Ohdaka-cho, Midori-ku, Nagoya 459-8522 (Japan); Shiohara, Y. [Superconductivity Research Laboratory, 1-10-13, Shinonome, Koto-ku, Tokyo 135-0062 (Japan)

    2009-10-15

    We fabricated 1 m high temperature superconducting conductor (HTS conductor) using YBa{sub 2}Cu{sub 3}O{sub 7-x} coated conductors (YBCO tapes) on textured metal substrates, which are expected to be lower in cost than YBCO tapes using ion-beam assisted deposition. Those substrate and intermediate layers were manufactured by Furukawa Electric, and YBCO and a protective layer were applied to the intermediate layer by Chubu Electric Power. Before fabricating the conductor, a 0.1 mm thick copper tape was soldered to the YBCO tape, and 10 mm wide YBCO tape was divided into three strips by a YAG laser. To have sufficient current capacity for 1 kA, a two-layer conductor was fabricated, and its critical current (I{sub c}) was 1976 A, but the magnetic properties of the textured metal substrates affected the increase in AC loss. In a low current region, the AC loss in this conductor was much higher than the Norris strip model, but approached the Norris strip model in the high current region because the magnetization was almost saturated. Low AC loss of 0.144 W/m at 1 kA{sub rms} was achieved even though the conductor had a small outer diameter of 20 mm and was composed of YBCO tapes with magnetic substrates.

  8. Recent Developments of Flexible CdTe Solar Cells on Metallic Substrates: Issues and Prospects

    Directory of Open Access Journals (Sweden)

    M. M. Aliyu

    2012-01-01

    Full Text Available This study investigates the key issues in the fabrication of CdTe solar cells on metallic substrates, their trends, and characteristics as well as effects on solar cell performance. Previous research works are reviewed while the successes, potentials, and problems of such technology are highlighted. Flexible solar cells offer several advantages in terms of production, cost, and application over glass-based types. Of all the metals studied as substrates for CdTe solar cells, molybdenum appears the most favorable candidate, while close spaced sublimation (CSS, electrodeposition (ED, magnetic sputtering (MS, and high vacuum thermal evaporation (HVE have been found to be most common deposition technologies used for CdTe on metal foils. The advantages of these techniques include large grain size (CSS, ease of constituent control (ED, high material incorporation (MS, and low temperature process (MS, HVE, ED. These invert-structured thin film CdTe solar cells, like their superstrate counterparts, suffer from problems of poor ohmic contact at the back electrode. Thus similar strategies are applied to minimize this problem. Despite the challenges faced by flexible structures, efficiencies of up to 13.8% and 7.8% have been achieved in superstrate and substrate cell, respectively. Based on these analyses, new strategies have been proposed for obtaining cheaper, more efficient, and viable flexible CdTe solar cells of the future.

  9. Non-c-axis-Oriented EuBa2Cu3O7-δ Thin Films Grown on Al2O3\\mbi{(1\\bar{1}02)} Substrates with CeO2 Buffer Layers

    Science.gov (United States)

    Wakana, Hironori; Yokosawa, Atsushi; Michikami, Osamu

    1999-10-01

    EuBa2Cu3O7-δ (EBCO) thin films with different growth orientations were prepared on Al2O3(1\\bar{1}02) substrates with CeO2 buffer layers by dc magnetron sputtering. The EBCO thin films were deposited immediately after off-axis rf magnetron sputtering of CeO2(001) films. The effects of substrate temperature and oxygen concent on epitaxial orientation of EBCO thin films were examined. With the increase in oxygen concentration, the surface roughness of an EBCO thin film increased. An appropriate oxygen concentration existed. It was clarified that the orientation of an EBCO thin film depended on CeO2 film thickness. The (100)- and (110)-oriented EBCO thin films were obtained on CeO2 buffer layers 30 90 Å thick and more than 700 Å thick, respectively. The (100)- and (110)-oriented EBCO films had in-plane epitaxial orientation relationships of Al_2O_3[11\\bar{2}0] \\parallel CeO_2[100] \\parallel EBCO[013] and Al_2O_3[11\\bar{2}0] \\parallel CeO_2[100] \\parallel EBCO[1\\bar{1}0], respectively. The (100)-oriented EBCO films deposited on 50-Å-thick CeO2 (001) buffer layers had Tce's of 72.0 K, and (110)-oriented EBCO films deposited on 750-Å-thick CeO2(001) buffer layers had Tce's of 70.0 K. The Tce decreased with increasing CeO2 buffer layer thickness above 800 Å. The a-axis-oriented EBCO thin films exhibited Tce's of about 85.4 K on the 50-Å-thick CeO2 buffer layers prepared by a self-template method.

  10. Reversible electron-transfer reactions within a nanoscale metal oxide cage mediated by metallic substrates.

    Science.gov (United States)

    Fleming, Christopher; Long, De-Liang; McMillan, Nicola; Johnston, Jacqueline; Bovet, Nicolas; Dhanak, Vin; Gadegaard, Nikolaj; Kögerler, Paul; Cronin, Leroy; Kadodwala, Malcolm

    2008-04-01

    Transition metal oxides exhibit a rich collection of electronic properties and have many practical applications in areas such as catalysis and ultra-high-density magnetic data storage. Therefore the development of switchable molecular transition metal oxides has potential for the engineering of single-molecule devices and nanoscale electronics. At present, the electronic properties of transition metal oxides can only be tailored through the irreversible introduction of dopant ions, modifying the electronic structure by either injecting electrons or core holes. Here we show that a molybdenum(VI) oxide 'polyoxometalate' molecular nanocluster containing two embedded redox agents is activated by a metallic surface and can reversibly interconvert between two electronic states. Upon thermal activation two electrons are ejected from the active sulphite anions and delocalized over the metal oxide cluster cage, switching it from a fully oxidized state to a two-electron reduced state along with the concomitant formation of an S-S bonding interaction between the two sulphur centres inside the cluster shell.

  11. Buffer architecture for biaxially textured structures and method of fabricating same

    Science.gov (United States)

    Norton, David P.; Park, Chan; Goyal, Amit

    2004-04-06

    The invention relates to an article with an improved buffer layer architecture comprising a substrate having a metal surface, and an epitaxial buffer layer on the surface of the substrate. The epitaxial buffer layer comprises at least one of the group consisting of ZrO.sub.2, HfO.sub.2, and compounds having at least one of Ca and a rare earth element stabilizing cubic phases of ZrO.sub.2 and/or HfO.sub.2. The article can also include a superconducting layer deposited on the epitaxial buffer layer. The article can also include an epitaxial capping layer between the epitaxial buffer layer and the superconducting layer. A method for preparing an epitaxial article comprises providing a substrate with a metal surface, depositing on the metal surface an epitaxial buffer layer comprising at least one material selected from the group consisting of ZrO.sub.2, HfO.sub.2, and compounds having at least one of Ca and a rare earth element stabilizing cubic phases of at least one of ZrO.sub.2 and HfO.sub.2. The epitaxial layer depositing step occurs in a vacuum with a background pressure of no more than 1.times.10.sup.-5 Torr. The method can further comprise depositing a superconducting layer on the epitaxial layer, and depositing an epitaxial capping layer between the epitaxial buffer layer and the superconducting layer.

  12. Fracture characterization of inhomogeneous wrinkled metallic films deposited on soft substrates

    Science.gov (United States)

    Kishida, Hiroshi; Ishizaka, Satoshi; Nagakura, Takumi; Suzuki, Hiroaki; Yonezu, Akio

    2017-12-01

    This study investigated the fracture properties of wrinkled metallic films on a polydimethylsiloxane (PDMS) soft substrate. In particular, the crack density of the wrinkled film during tensile deformation was examined. In order to achieve better deformability of metallic thin films, a method to fabricate a wrinkled thin film on a PDMS soft substrate was first established. The copper (Cu) nano-film fabricated in this study possessed a wrinkled geometry, which plays a critical role in determining the extent of large elastic deformation. To create the wrinkled structure, wet-etching with a polymeric sacrificial layer was used. A sacrificial layer was first deposited onto a silicone rubber sheet. During the curing process of the layer, a compressive strain was applied such that the hardened surface layer buckled, and a wrinkled form was obtained. Subsequently, a PDMS solution was used to cover the layer in order to form a wrinkled PDMS substrate. Finally, the Cu film was deposited onto the wrinkled PDMS, such that the wrinkled Cu film on a soft PDMS substrate was fabricated. The use of uni-axial tensile tests resulted in film crack generation at the stress concentration zone in the wrinkled structure of the films. When the tensile loading was increased, the number of cracks increased. It was found that the increase in crack density was strongly related to the inhomogeneous nature of the wrinkled structure. Such a trend in crack density was investigated using FEM (finite element method) computations, such that this study established a simple mechanical model that may be used to predict the increase in crack density during tensile deformation. This model was verified through several experiments using various wrinkle patterns. The proposed mechanical model may be useful to predict the crack density of a wrinkled metallic film subject to tensile loading.

  13. Rational composition control of mixed-lanthanide metal-organic frameworks by an interfacial reaction with metal ion-doped polymer substrates

    Science.gov (United States)

    Tsuruoka, Takaaki; Miyanaga, Ayumi; Ohhashi, Takashi; Hata, Manami; Takashima, Yohei; Akamatsu, Kensuke

    2017-09-01

    A simple composition control route to mixed-lanthanide metal-organic frameworks (MOFs) was developed based on an interfacial reaction with mixed-lanthanide metal ion-doped polymer substrates. By controlling the composition of lanthanide ion (Eu3+ and Tb3+) dopants in polymer substrates to be used as metal ion precursors and scaffolding for the formation of MOFs, [EuxTb2-x(bdc)3(H2O)4]n crystals with a tunable metal composition could be routinely prepared on polymer substrates. Inductively coupled plasma (ICP) measurements revealed that the composition of the obtained frameworks was almost the same as that of the initial polymer substrates. In addition, the resulting [EuxTb2-x(bdc)3(H2O)4]n crystals showed strong phosphorescence because of Eu3+ transitions, indicating that the energy transfer from Tb3+ to Eu3+ ions in the frameworks could be achieved with high efficiency.

  14. Ab initio investigations of magnetic properties of ultrathin transition-metal films on 4d substrates

    Energy Technology Data Exchange (ETDEWEB)

    Al-Zubi, Ali

    2010-12-22

    In this thesis, we investigate the magnetic properties of 3d transition-metal monolayers on 4d transition-metal substrates by means of state of the art first-principles quantum theory. In order to reveal the underlying physics of these systems we study trends by performing systematic investigations across the transition-metal series. Case studies are presented for which Rh has been chosen as exemplary 4d substrate. We consider two substrate orientations, a square lattice provided by Rh(001) and a hexagonal lattice provided by Rh(111). We find, all 3d transition-metal (V, Cr, Mn, Fe, Co and Ni) monolayers deposited on the Rh substrate are magnetic and exhibit large local moments which follow Hund's rule with a maximum magnetic moment for Mn of about 3.7 {mu}{sub B} depending on the substrate orientation. The largest induced magnetic moment of about 0.46 {mu}{sub B} is found for Rh atoms adjacent to the Co(001)-film. On Rh(001) we predict a ferromagnetic (FM) ground state for V, Co and Ni, while Cr, Mn and Fe monolayers favor a c(2 x 2) antiferromagnetic (AFM) state, a checkerboard arrangement of up and down magnetic moments. The magnetic anisotropy energies of these ultrathin magnetic films are calculated for the FM and the AFM states. With the exception of V and Cr, the easy axis of the magnetization is predicted to be in the film plane. With the exception of Fe, analogous results are obtained for the 3d-metal monolayers on Rh(111). For Fe on Rh(111) a novel magnetic ground state is predicted, a double-row-wise antiferromagnetic state along the [11 anti 2] direction, a sequence of ferromagnetic double-rows of atoms, whose magnetic moments couple antiferromagnetically from double row to double row. The magnetic structure can be understood as superposition of a left- and right-rotating flat spin spiral. In a second set of case studies the properties of an Fe monolayer deposited on varies hexagonally terminated hcp (0001) and fcc (111) surfaces of 4d

  15. Effect of buffer-layered buttering on microstructure and mechanical properties of dissimilar metal weld joints for nuclear plant application

    Energy Technology Data Exchange (ETDEWEB)

    Rathod, Dinesh W., E-mail: dineshvrathod@gmail.com [Department of Mechanical Enggineering, Indian Institute of Technology Delhi, Hauz-khas, New Delhi 110016 (India); Singh, P.K. [Bhabha Atomic Research Centre, Mumbai 400085 (India); Pandey, Sunil; Aravindan, S. [Department of Mechanical Enggineering, Indian Institute of Technology Delhi, Hauz-khas, New Delhi 110016 (India)

    2016-06-01

    In this study, we present the metallurgical and mechanical investigation of four dissimilar welds between SA508Gr.3Cl.1 and SS304LN. The welding processes for buttering deposition and fill-pass welding were varied with ERNiCr-3/ENiCrFe-3 consumables. The Ni-Fe alloy buffer layer was introduced as intermediate layer in buttering and then the joints (with and without buffer layer in buttering) were fabricated. The effect of Ni-Fe buffer layered buttering and welding processes on the resulting weld joints properties has been addressed. Metallurgical and mechanical properties, fracture toughness were measured and various examinations were carried out for integrity assessment on all the weld joints. Addition of a Ni-Fe buttering layer leads to the development of more favourable properties than observed in welded joints made using the current practice without a buffer layer. Control of carbon migration and its subsequent effect on metallurgical, mechanical properties due to buffer layer has been justified in the study. Conventional procedure of DMW fabrication has been proven to be the least favourable against the new technique suggested. Modification in current integrity assessment procedure would be possible by considering the properties at interfacial regions, introduction of yield strength ratio mismatch and the plastic instability strength in the integrity assessment.

  16. Metal Nanoparticles Deposited on Porous Silicon Templates as Novel Substrates for SERS

    Directory of Open Access Journals (Sweden)

    Lara Mikac

    2015-12-01

    Full Text Available In this paper, results on preparation of stable and uniform SERS solid substrates using macroporous silicon (pSi with deposited silver and gold are presented. Macroporous silicon is produced by anodisation of p-type silicon in hydrofluoric acid. The as prepared pSi is then used as a template for Ag and Au depositions. The noble metals were deposited in three different ways: by immersion in silver nitrate solution, by drop-casting silver colloidal solution and by pulsed laser ablation (PLA. Substrates obtained by different deposition processes were evaluated for SERS efficiency using methylene blue (MB and rhodamine 6G (R6G at 514.5, 633 and 785 nm. Using 514.5 nm excitation and R6G the limits of detection (LOD for macroporous Si samples with noble metal nanostructures obtained by immersion of pSi sample in silver nitrate solution and by applying silver colloidal solution to pSi template were 10–9 M and 10–8 M respectively. Using 633 nm laser and MB the most noticeable SERS activity gave pSi samples ablated with 30000 and 45000 laser pulses where the LODs of 10–10 M were obtained. The detection limit of 10–10 M was also reached for 4 mA cm–2-15 min pSi sample, silver ablated with 30000 pulses. Macroporous silicon proved to be a good base for the preparation of SERS substrates.

  17. Direct observation of small cluster mobility and ripening. [during annealing of metal films on amorphous substrates

    Science.gov (United States)

    Heinemann, K.; Poppa, H.

    1975-01-01

    Direct evidence is reported for the simultaneous occurrence of Ostwald ripening and short-distance cluster mobility during annealing of discontinuous metal films on clean amorphous substrates. The annealing characteristics of very thin particulate deposits of silver on amorphized clean surfaces of single crystalline thin graphite substrates were studied by in-situ transmission electron microscopy (TEM) under controlled environmental conditions (residual gas pressure of 10 to the minus 9th power torr) in the temperature range from 25 to 450 C. Sputter cleaning of the substrate surface, metal deposition, and annealing were monitored by TEM observation. Pseudostereographic presentation of micrographs in different annealing stages, the observation of the annealing behavior at cast shadow edges, and measurements with an electronic image analyzing system were employed to aid the visual perception and the analysis of changes in deposit structure recorded during annealing. Slow Ostwald ripening was found to occur in the entire temperature range, but the overriding surface transport mechanism was short-distance cluster mobility.

  18. Selective synthesis of double helices of carbon nanotube bundles grown on treated metallic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes-Sodi, Felipe; Iniguez-Rabago, Agustin; Rosas-Melendez, Samuel; Ballesteros-Villarreal, Monica [Departamento de Fisica y Matematicas, Universidad Iberoamericana, Prolongacion Paseo de la Reforma 880, Lomas de Santa Fe (Mexico); Vilatela, Juan J. [IMDEA Materials Institute, E.T.S. de Ingenieros de Caminos, Madrid (Spain); Reyes-Gutierrez, Lucio G.; Jimenez-Rodriguez, Jose A. [Ingenieria Industrial, Grupo JUMEX, Ecatepec de Morelos, Estado de Mexico (Mexico); Palacios, Eduardo [Lab. de Microscopia Electronica de Ultra Alta Resolucion, Instituto Mexicano del Petroleo, San Bartolo Atepehuacan (Mexico); Terrones, Mauricio [Department of Physics, Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University, University Park, PA (United States); Research Center for Exotic Nanocarbons (JST), Shinshu University, Nagano (Japan)

    2012-12-15

    Double-helix microstructures consisting of two parallel strands of hundreds of multi-walled carbon nanotubes (MWCNTs) have been synthesized by chemical vapour deposition of ferrocene/toluene vapours on metal substrates. Growth of coiled carbon nanostructures with site selectivity is achieved by varying the duration of thermochemical pretreatment to deposit a layer of SiO{sub x} on the metallic substrate. Production of multibranched structures of MWCNTs converging in SiO{sub x} microstructure is also reported. In the abstract figure, panel (a) shows a coloured micrograph of a typical double-helix coiled microstructure of MWCNTs grown on SiO{sub x} covered steel substrate. Green and blue show each of the two individual strands of MWCNTs. Panel (b) is an amplification of a SiO{sub x} microparticle (white) on the tip of the double-stranded coil (green and blue). The microparticle guides the collective growth of hundreds of MWCNTs to form the coiled structure. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Metal powder substrate-assisted laser desorption/ionization mass spectrometry for polyethylene analysis.

    Science.gov (United States)

    Yalcin, Talat; Wallace, William E; Guttman, Charles M; Li, Liang

    2002-09-15

    Polyethylene is one of the most important industrial polymers and is also one of the most challenging polymers to be characterized by mass spectrometry. We have developed a substrate-assisted laser desorption/ionization (LDI) mass spectrometric method for polyethylene analysis. In this method, cobalt, copper, nickel, or iron metal powders are used as a sample substrate and silver nitrate is used as the cationization reagent. Using a conventional UV LDI time-of-flight mass spectrometer, intact oligomer ions having masses up to 5000 u can be detected. Cobalt is found to produce spectra with the highest signal-to-noise ratio and the lowest level of fragmentation. Cobalt powder size is shown to have some effect on the spectra produced. The best results are obtained with the use of cobalt powders with diameters ranging from 30 to 100 microm. Fragmentation cannot be totally eliminated, but the fragment ion peaks can be readily discerned from the intact polyethylene ions in the substrate-assisted LDI spectrum. Thus, the average molecular masses of low-mass polyethylene samples can be determined by using this method. A rapid heating model is used to account for the effectiveness of using the coarse metal powders to assist the analysis of intact polyethylene molecules by LDI.

  20. Protein-associated water and secondary structure effect removal of blood proteins from metallic substrates.

    Science.gov (United States)

    Anand, Gaurav; Zhang, Fuming; Linhardt, Robert J; Belfort, Georges

    2011-03-01

    Removing adsorbed protein from metals has significant health and industrial consequences. There are numerous protein-adsorption studies using model self-assembled monolayers or polymeric substrates but hardly any high-resolution measurements of adsorption and removal of proteins on industrially relevant transition metals. Surgeons and ship owners desire clean metal surfaces to reduce transmission of disease via surgical instruments and minimize surface fouling (to reduce friction and corrosion), respectively. A major finding of this work is that, besides hydrophobic interaction adhesion energy, water content in an adsorbed protein layer and secondary structure of proteins determined the access and hence ability to remove adsorbed proteins from metal surfaces with a strong alkaline-surfactant solution (NaOH and 5 mg/mL SDS in PBS at pH 11). This is demonstrated with three blood proteins (bovine serum albumin, immunoglobulin, and fibrinogen) and four transition metal substrates and stainless steel (platinum (Pt), gold (Au), tungsten (W), titanium (Ti), and 316 grade stainless steel (SS)). All the metallic substrates were checked for chemical contaminations like carbon and sulfur and were characterized using X-ray photoelectron spectroscopy (XPS). While Pt and Au surfaces were oxide-free (fairly inert elements), W, Ti, and SS substrates were associated with native oxide. Difference measurements between a quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance spectroscopy (SPR) provided a measure of the water content in the protein-adsorbed layers. Hydrophobic adhesion forces, obtained with atomic force microscopy, between the proteins and the metals correlated with the amount of the adsorbed protein-water complex. Thus, the amount of protein adsorbed decreased with Pt, Au, W, Ti and SS, in this order. Neither sessile contact angle nor surface roughness of the metal substrates was useful as predictors here. All three globular proteins

  1. Computer Simulation of Metal Ions Transport to Uneven Substrates during Ionized Plasma Vapour Deposition

    Directory of Open Access Journals (Sweden)

    Tomáš Ibehej

    2017-01-01

    Full Text Available We present a computational study of processes taking place in a sheath region formed near a negatively biased uneven substrate during ionized plasma vapour deposition. The sputtered metal atoms are ionized on their way to substrate and they are accelerated in the sheath near the substrate. They are able to penetrate to high-aspect-ratio structures, for example, trenches, which can be, therefore, effectively coated. The main technique used was a two-dimensional particle simulation. The results of our model predict the energy and angular distributions of impinging ions in low-pressure conditions which are characteristic for this method and where typical continuous models fail due to unfulfilled assumptions. Input bulk plasma properties were computed by a “zero dimensional” global model which took into account more physical processes important on a scale of the whole magnetron chamber. Output parameters, such as electrostatic potential, energy of ions, and ion fluxes, were computed for wide range of conditions (electron density and substrate bias to show the influence of these conditions on observed phenomena, penetration of sheath inside the trench, deceleration of argon and copper ions inside the trench, and local maxima of ion fluxes near the trench opening.

  2. The effect of polyimide imidization conditions on adhesion strength of thin metal films on polyimide substrates

    CERN Document Server

    Yoo, S H

    1999-01-01

    The effects of Ar sup + RF plasma precleaning and polyimide curing conditions on the peel strength between Al thin films and polyimides have been studied. The BPDA-PDA polyimide precursor of PI-2611 (Du pont) was spin-coated and cured under various imidization conditions. The cured polyimide substrates were in-situ AR sup + RF plasma cleaned prior to metal deposition. Al-1 % Si-0.5 % Cu thin films were deposited onto the polyimide substrates by using DC magnetron sputtering. The peel strength was enhanced by Ar sup + RF plasma precleaning. The Al/modified PI specimen failed cohesively in the polyimide. The polyimide curing conditions strongly affect the peel strength in the Al/modified PI system.

  3. Stabilization of ultrathin (hydroxy)oxide films on transition metal substrates for electrochemical energy conversion

    Science.gov (United States)

    Zeng, Zhenhua; Chang, Kee-Chul; Kubal, Joseph; Markovic, Nenad M.; Greeley, Jeffrey

    2017-06-01

    Design of cost-effective electrocatalysts with enhanced stability and activity is of paramount importance for the next generation of energy conversion systems, including fuel cells and electrolysers. However, electrocatalytic materials generally improve one of these properties at the expense of the other. Here, using density functional theory calculations and electrochemical surface science measurements, we explore atomic-level features of ultrathin (hydroxy)oxide films on transition metal substrates and demonstrate that these films exhibit both excellent stability and activity for electrocatalytic applications. The films adopt structures with stabilities that significantly exceed bulk Pourbaix limits, including stoichiometries not found in bulk and properties that are tunable by controlling voltage, film composition, and substrate identity. Using nickel (hydroxy)oxide/Pt(111) as an example, we further show how the films enhance activity for hydrogen evolution through a bifunctional effect. The results suggest design principles for this class of electrocatalysts with simultaneously enhanced stability and activity for energy conversion.

  4. Preparation and characterization of well-ordered, thin niobia films on a metal substrate

    Science.gov (United States)

    Starr, D. E.; Mendes, F. M. T.; Middeke, J.; Blum, R.-P.; Niehus, H.; Lahav, D.; Guimond, S.; Uhl, A.; Kluener, T.; Schmal, M.; Kuhlenbeck, H.; Shaikhutdinov, S.; Freund, H.-J.

    2005-12-01

    Combining low energy electron diffraction, scanning tunneling microscopy, angular resolved photoelectron spectroscopy using synchrotron radiation and density functional theory calculations, we have studied the structure of thin niobia films grown on a Cu 3Au(1 0 0) substrate. Nb deposition onto oxygen implanted Cu 3Au(1 0 0) and subsequent oxidation results in a flat, well-ordered thin niobia film of hexagonal symmetry. The results suggest that the film consists of 2/3 ML of Nb between two hexagonal O-layers, where Nb 5+ cations occupy the threefold hollow sites. This leads to a (√{3}×√{3})R30° structure with respect to the underlying close packed O layer, which in turn forms a (2 × 7) coincidence structure with the metal substrate. The defect structure includes reflection domain boundaries and vacancies.

  5. Development of Ceramic Coating on Metal Substrate using Industrial Waste and Ore Minerals

    Science.gov (United States)

    Bhuyan, S. K.; Thiyagarajan, T. K.; Mishra, S. C.

    2017-02-01

    The technological advancement in modern era has a boon for enlightening human life; but also is a bane to produce a huge amount of (industrial) wastes, which is of great concern for utilization and not to create environmental threats viz. polution etc. In the present piece of research work, attempts have been made to utilize fly ash (wastes of thermal power plants) and along with alumina bearing ore i.e. bauxite, for developing plasma spray ceramic coatings on metals. Fly ash and with 10 and 20% bauxite addition is used to deposit plasma spray coatings on a metal substrate. The surface morphology of the coatings deposited at different power levels of plasma spraying investigated through SEM and EDS analysis. The coating thickness is measured. The porosity levels of the coatings are evaluated. The coating hardness isalso measured. This piece of research work will be beneficial for future development and use of industrial waste and ore minerals for high-valued applications.

  6. Organic molecules on metal and oxide semiconductor substrates: Adsorption behavior and electronic energy level alignment

    Science.gov (United States)

    Ruggieri, Charles M.

    Modern devices such as organic light emitting diodes use organic/oxide and organic/metal interfaces for crucial processes such as charge injection and charge transfer. Understanding fundamental physical processes occurring at these interfaces is essential to improving device performance. The ultimate goal of studying such interfaces is to form a predictive model of interfacial interactions, which has not yet been established. To this end, this thesis focuses on obtaining a better understanding of fundamental physical interactions governing molecular self-assembly and electronic energy level alignment at organic/metal and organic/oxide interfaces. This is accomplished by investigating both the molecular adsorption geometry using scanning tunneling microscopy, as well as the electronic structure at the interface using direct and inverse photoemission spectroscopy, and analyzing the results in the context of first principles electronic structure calculations. First, we study the adsorption geometry of zinc tetraphenylporphyrin (ZnTPP) molecules on three noble metal surfaces: Au(111), Ag(111), and Ag(100). These surfaces were chosen to systematically compare the molecular self-assembly and adsorption behavior on two metals of the same surface symmetry and two surface symmetries of one metal. From this investigation, we improve the understanding of self-assembly at organic/metal interfaces and the relative strengths of competing intermolecular and molecule-substrate interactions that influence molecular adsorption geometry. We then investigate the electronic structure of the ZnTPP/Au(111), Ag(111), and Ag(100) interfaces as examples of weakly-interacting systems. We compare these cases to ZnTPP on TiO2(110), a wide-bandgap oxide semiconductor, and explain the intermolecular and molecule-substrate interactions that determine the electronic energy level alignment at the interface. Finally we study tetracyanoquinodimethane (TCNQ), a strong electron acceptor, on TiO2

  7. Phosphate chemical conversion coatings on metallic substrates for biomedical application: a review.

    Science.gov (United States)

    Liu, Bing; Zhang, Xian; Xiao, Gui-yong; Lu, Yu-peng

    2015-02-01

    Phosphate chemical conversion (PCC) technology has been investigated for improving the surface performance of metallic implants in the biomedical field over the last decade. The metallic materials, such as magnesium and its alloys, titanium, pure iron and stainless steel are widely used as orthopedic devices for immobilization of bone fractures in clinic. They were previously studied as metal substrates for PCC coating aiming to modify their biocompatibility and osteoconductivity. Zinc, calcium and zinc-calcium PCC coatings are frequently utilized considering their nature and the end-use. Although PCC coating has been confirmed to potentially improve the bio-performance of metallic implants in vitro and in vivo by many researchers, there are no unified standards or regulations to give quantitative appraisal of its quality and property. As such, an overview of several main phosphate phases together with their properties and behaviors in vitro and in vivo was conducted. The mechanism of phosphating was also briefly discussed. Critical qualities of PCC coating used for biomedical application including corrosion resistance, wettability and bonding strength were analyzed separately. Biological response including in vitro cell investigations and in vivo tissue response were discussed in terms of the cytocompatibility and bioactivity of PCC coating. Further investigations are proposed to develop appropriate performance evaluation measurements by combining conventional technologies and biomedical procedures. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Adsorption of metal nanoparticles on carbon substrates and epitaxial graphene: Assessing models for dispersion forces

    Science.gov (United States)

    Förster, G. D.; Rabilloud, F.; Calvo, F.

    2015-06-01

    Carbon substrates such as graphite or epitaxial graphene can be employed to support metal nanoparticles for applications in diverse areas of surface science. In this paper, we address the computational modeling of such systems by means of semiempirical potentials, and in particular the possible role of long-range London dispersion forces. Following the Grimme (D2) strategy often used in combination with density-functional theory calculations, we propose some analytical extensions taking into account the crystalline and semi-infinite natures of the substrate and, in the case of epitaxial graphene, the possible screening of the van der Waals interaction by the bulk underlying metal. These ideas are tested in the specific case of platinum nanoparticles deposited on graphene, graphite, and graphene epitaxially grown on Pt(111) modeled using a many-body Brenner-type potential, and validated against available electronic-structure calculations. Systematic optimizations carried out at zero temperature indicate the relative stability of various nanoparticle shapes on their support, for adsorbates containing several thousand atoms. Using molecular dynamics simulations, we shed light on the thermal behavior and emphasize the key role of dispersion forces on the stabilization of the adsorbates at finite temperature. The vibrational properties of graphene layers in contact with a Pt nanoparticle or epitaxially grown on Pt(111) also reveal some clear sensitivity on temperature and strain.

  9. Construction of 3D Metallic Nanowire Arrays on Arbitrarily-Shaped Substrate.

    Science.gov (United States)

    Chen, Fei; Li, Jingning; Yu, Fangfang; Peng, Ru-Wen; Wang, Mu; Mu Wang Team

    Formation of three-dimensional (3D) nanostructures is an important step of advanced manufacture for new concept devices with novel functionality. Despite of great achievements in fabricating nanostructures with state of the art lithography approaches, these nanostructures are normally limited on flat substrates. Up to now it remains challenging to build metallic nanostructures directly on a rough and bumpy surface. Here we demonstrate a unique approach to fabricate metallic nanowire arrays on an arbitrarily-shaped surface by electrodeposition, which is unknown before 2016. Counterintuitively here the growth direction of the nanowires is perpendicular to their longitudinal axis, and the specific geometry of nanowires can be achieved by introducing specially designed shaped substrate. The spatial separation and the width of the nanowires can be tuned by voltage, electrolyte concentration and temperature in electrodeposition. By taking cobalt nanowire array as an example, we demonstrate that head-to-head and tail-to-tail magnetic domain walls can be easily introduced and modulated in the nanowire arrays, which is enlightening to construct new devices such as domain wall racetrack memory. We acknowledge the foundation from MOST and NSF(China).

  10. Long-range wetting transparency on top of layered metal-dielectric substrates

    Science.gov (United States)

    Noginov, M. A.; Barnakov, Yuri A.; Liberman, Vladimir; Prayakarao, Srujana; Bonner, Carl E.; Narimanov, Evgenii E.

    2016-06-01

    It has been recently shown that scores of physical and chemical phenomena (including spontaneous emission, scattering and Förster energy transfer) can be controlled by nonlocal dielectric environments provided by metamaterials with hyperbolic dispersion and simpler metal/dielectric structures. At this time, we have researched van der Waals interactions and experimentally studied wetting of several metallic, dielectric and composite multilayered substrates. We have found that the wetting angle of water on top of MgF2 is highly sensitive to the thickness of the MgF2 layer and the nature of the underlying substrate that could be positioned as far as ~100 nm beneath the water/MgF2 interface. We refer to this phenomenon as long range wetting transparency. The latter effect cannot be described in terms of the most basic model of dispersion van der Waals-London forces based on pair-wise summation of dipole-dipole interactions across an interface or a gap separating the two media. We infer that the experimentally observed gradual change of the wetting angle with increase of the thickness of the MgF2 layer can possibly be explained by the distance dependence of the Hamaker function (describing the strength of interaction), which originates from retardation of electromagnetic waves at the distances comparable to a wavelength.

  11. Metallization and biopatterning on ultra-flexible substrates via dextran sacrificial layers.

    Science.gov (United States)

    Tseng, Peter; Pushkarsky, Ivan; Di Carlo, Dino

    2014-01-01

    Micro-patterning tools adopted from the semiconductor industry have mostly been optimized to pattern features onto rigid silicon and glass substrates, however, recently the need to pattern on soft substrates has been identified in simulating cellular environments or developing flexible biosensors. We present a simple method of introducing a variety of patterned materials and structures into ultra-flexible polydimethylsiloxane (PDMS) layers (elastic moduli down to 3 kPa) utilizing water-soluble dextran sacrificial thin films. Dextran films provided a stable template for photolithography, metal deposition, particle adsorption, and protein stamping. These materials and structures (including dextran itself) were then readily transferrable to an elastomer surface following PDMS (10 to 70∶1 base to crosslinker ratios) curing over the patterned dextran layer and after sacrificial etch of the dextran in water. We demonstrate that this simple and straightforward approach can controllably manipulate surface wetting and protein adsorption characteristics of PDMS, covalently link protein patterns for stable cell patterning, generate composite structures of epoxy or particles for study of cell mechanical response, and stably integrate certain metals with use of vinyl molecular adhesives. This method is compatible over the complete moduli range of PDMS, and potentially generalizable over a host of additional micro- and nano-structures and materials.

  12. Metallization and biopatterning on ultra-flexible substrates via dextran sacrificial layers.

    Directory of Open Access Journals (Sweden)

    Peter Tseng

    Full Text Available Micro-patterning tools adopted from the semiconductor industry have mostly been optimized to pattern features onto rigid silicon and glass substrates, however, recently the need to pattern on soft substrates has been identified in simulating cellular environments or developing flexible biosensors. We present a simple method of introducing a variety of patterned materials and structures into ultra-flexible polydimethylsiloxane (PDMS layers (elastic moduli down to 3 kPa utilizing water-soluble dextran sacrificial thin films. Dextran films provided a stable template for photolithography, metal deposition, particle adsorption, and protein stamping. These materials and structures (including dextran itself were then readily transferrable to an elastomer surface following PDMS (10 to 70∶1 base to crosslinker ratios curing over the patterned dextran layer and after sacrificial etch of the dextran in water. We demonstrate that this simple and straightforward approach can controllably manipulate surface wetting and protein adsorption characteristics of PDMS, covalently link protein patterns for stable cell patterning, generate composite structures of epoxy or particles for study of cell mechanical response, and stably integrate certain metals with use of vinyl molecular adhesives. This method is compatible over the complete moduli range of PDMS, and potentially generalizable over a host of additional micro- and nano-structures and materials.

  13. Characterization of a strongly textured non-ferromagnetic Cu-33 at%Ni substrate coated with a CeO2 buffer layer

    DEFF Research Database (Denmark)

    Tian, Hui; Suo, H.L.; Yue, Zhao

    2013-01-01

    the fraction of the cube {001}〈100〉 texture is 99.8% and the fraction of boundary misorientations with angles greater than 10 is only 5%. The material is shown to be non-ferromagnetic at typical operating temperatures for coated conductors. Furthermore, it is shown that a CeO2 buffer layer can be successfully...

  14. Active vacuum brazing of CNT films to metal substrates for superior electron field emission performance.

    Science.gov (United States)

    Longtin, Rémi; Ramon Sanchez-Valencia, Juan; Shorubalko, Ivan; Furrer, Roman; Hack, Erwin; Elsener, Hansrudolf; Gröning, Oliver; Greenwood, Paul; Rupesinghe, Nalin; Teo, Kenneth; Leinenbach, Christian; Gröning, Pierangelo

    2015-02-01

    The joining of macroscopic films of vertically aligned multiwalled carbon nanotubes (CNTs) to titanium substrates is demonstrated by active vacuum brazing at 820 °C with a Ag-Cu-Ti alloy and at 880 °C with a Cu-Sn-Ti-Zr alloy. The brazing methodology was elaborated in order to enable the production of highly electrically and thermally conductive CNT/metal substrate contacts. The interfacial electrical resistances of the joints were measured to be as low as 0.35 Ω. The improved interfacial transport properties in the brazed films lead to superior electron field-emission properties when compared to the as-grown films. An emission current of 150 μA was drawn from the brazed nanotubes at an applied electric field of 0.6 V μm-1. The improvement in electron field-emission is mainly attributed to the reduction of the contact resistance between the nanotubes and the substrate. The joints have high re-melting temperatures up to the solidus temperatures of the alloys; far greater than what is achievable with standard solders, thus expanding the application potential of CNT films to high-current and high-power applications where substantial frictional or resistive heating is expected.

  15. Nanotribological properties of water films adsorbing atop, and absorbing below, graphene layers supported by metal substrates

    Science.gov (United States)

    Liu, Zijian; Curtis, C. K.; Stine, R.; Sheehan, P.; Krim, J.

    The tribological properties of graphite, a common lubricant with known sensitivity to the presence of water, have been studied extensively at the macroscopic and microscopic scales. Although far less attention has been devoted to the tribological properties of graphene, it has been established that the tribological response to the presence of water is dissimilar from that of graphite. We report here a quartz crystal microbalance study of the nanotribological properties of water films adsorbed/absorbed on graphene layers prepared by either chemical decomposition on nickel(111) substrates or transfer of freestanding graphene layers to aluminum substrates. Sliding friction levels of the water films were also measured for metal surfaces in the absence of a graphene layer. We observe very high friction levels for water adsorbed atop graphene on Ni(111) and very low levels for water on aluminum. For the case of graphene/aluminum, the data indicate that the water is absorbing between the graphene layer and the aluminum. Dissipation levels moreover indicate the presence of an interstitial water increases sliding friction between the graphene and the aluminum substrate Work supported by NSF and NRL.

  16. Evaluation and Characterization of Plasma Sprayed Cu Slag-Al Composite Coatings on Metal Substrates

    Directory of Open Access Journals (Sweden)

    S. Mantry

    2013-01-01

    Full Text Available Copper slag is a waste product obtained during matte smelting and refining of copper. The present work explores the coating potential of copper slag by plasma spraying. This work shows that copper slag is eminently coatable. An attempt has been made in the present investigation to use the composites coatings of copper slag and Al powder in suitable combination on aluminium and mild steel substrates in order to improve the surface properties of these ductile metal-alloy substrates. When premixed with Al powder, the coating exhibits higher interfacial adhesion as compared to pure copper slag coatings. Maximum adhesion strengths of about 23 MPa and 21 MPa are recorded for the coatings of copper slag with 15 wt% of Al on aluminium and mild steel substrates, respectively. The input power to the plasma torch is found to affect the coating deposition efficiency and morphology of the coatings. It also suggests value addition of an industrial waste.

  17. Surface resistances of EuBa 2Cu 3O 7- x thin films on Al 2O 3 substrates with CeO 2 buffer layers measured by using a TE 013-mode cylindrical cavity resonator

    Science.gov (United States)

    Hashimoto, T.; Obara, K.; Michikami, O.

    2002-10-01

    Epitaxial c-axis EuBa 2Cu 3O 7-x (EBCO) films were deposited on R-Al 2O 3 substrates with CeO 2 buffer layers of various thicknesses. EBCO films of different thicknesses were prepared at various substrate temperatures ( Ts), and their Rs values at 50 GHz and Jc (at 77.3 K) were measured. A 0.5-μm-thick EBCO film deposited on a 30-nm-thick CeO 2 buffer layer at T s=650 ° C showed a minimum Rs value of 6.6 m Ω and a Jc value of 0.99×10 6 A/cm 2 at 77.3 K. As-sputtered EBCO films of the same thickness deposited on MgO showed an Rs value of about 2 m Ω (extrapolation value) at 77.3 K. The Rs value of EBCO on R-Al 2O 3⧹CeO 2 was about three-times larger than that on MgO substrates. This result is due to the large asymmetry of R-Al 2O 3.

  18. Laser-induced spalling of thin metal film from silica substrate followed by inflation of microbump

    Science.gov (United States)

    Inogamov, N. A.; Zhakhovsky, V. V.; Migdal, K. P.

    2016-04-01

    Dynamics of a thin gold film on a silica substrate triggered by fast heating with the use of a subpicosecond laser pulse is studied. The pressure waves generated by such heating may result in spalling (delamination) of the film and its flying away from the substrate after an acoustic time defined by the film thickness and speed of sound in metal. Intensity of the heating laser beam has the spatial Gaussian distribution in a cross section. Therefore, the heating of film surface is non-uniform along cylindrical radius measured from the beam axis. As a result of such heating, the velocity distribution in material flying away from the substrate has a maximum at the beam axis. Thus, the separated film has dome-like shape which inflates with time. Volume of an empty cavity between the separated film and the substrate increases during inflation. Typical flight velocities are in the range of 30-200 m/s. The inflation stage can last from few to several tens of nanoseconds if the diffraction-limited micron-sized laser focal spots are used. Capillary forces acting along the warped flying film decelerate the inflation of dome. Capillary deceleration of a bulging dome focuses mass flow along the dome shell in the direction of its axis. This results in formation of an axial jet and droplet in a tip of the dome. Our new simulation results and comparisons with experiments are presented. The results explain appearance of debris in a form of frozen droplets on a surface of an irradiated spot. This is the consequence of the capillary return of a droplet.

  19. Back contact to film silicon on metal for photovoltaic cells

    Science.gov (United States)

    Branz, Howard M.; Teplin, Charles; Stradins, Pauls

    2013-06-18

    A crystal oriented metal back contact for solar cells is disclosed herein. In one embodiment, a photovoltaic device and methods for making the photovoltaic device are disclosed. The photovoltaic device includes a metal substrate with a crystalline orientation and a heteroepitaxial crystal silicon layer having the same crystal orientation of the metal substrate. A heteroepitaxial buffer layer having the crystal orientation of the metal substrate is positioned between the substrate and the crystal silicon layer to reduce diffusion of metal from the metal foil into the crystal silicon layer and provide chemical compatibility with the heteroepitaxial crystal silicon layer. Additionally, the buffer layer includes one or more electrically conductive pathways to electrically couple the crystal silicon layer and the metal substrate.

  20. Corrosion resistance of Ni-50Cr HVOF coatings on 310S alloy substrates in a metal dusting atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Saaedi, J. [Centre for Advanced Coating Technologies, Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario M5S 3E4 (Canada); Department of Materials and Metallurgical Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Arabi, H.; Mirdamadi, S.; Ghorbani, H. [Department of Materials and Metallurgical Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Coyle, T.W. [Centre for Advanced Coating Technologies, Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario M5S 3E4 (Canada)

    2011-09-15

    Metal dusting attack has been examined after three 168 h cycles on two Ni-50Cr coatings with different microstructures deposited on 310S alloy substrates by the high velocity oxy-fuel (HVOF) thermal-spray process. Metal dusting in uncoated 310S alloy specimens was found to be still in the initiation stage after 504 h of exposure in the 50H{sub 2}:50CO gas environment at 620 C. Dense Ni-50Cr coatings offered suitable resistance to metal dusting. Metal dusting was observed in the 310S substrates adjacent to pores at the interface between the substrate and a porous Ni-50Cr coating. The porosity present in the as-deposited coatings was shown to introduce a large variability into coating performance. Carbon formed by decomposition of the gaseous species accumulated in the surface pores and resulted in the dislodgement of surface splats due to stresses generated by the volume changes. When the corrosive gas atmosphere was able to penetrate through the interconnected pores and reach the coating-substrate interface, the 310S substrate was carburized, metal dusting attack occurred, and the resulting formation of coke in the pores led to local failure of the coating. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Nanoscale “Quantum” Islands on Metal Substrates: Microscopy Studies and Electronic Structure Analyses

    Directory of Open Access Journals (Sweden)

    Da-Jiang Liu

    2010-07-01

    Full Text Available Confinement of electrons can occur in metal islands or in continuous films grown heteroepitaxially upon a substrate of a different metal or on a metallic alloy. Associated quantum size effects (QSE can produce a significant height-dependence of the surface free energy for nanoscale thicknesses of up to 10–20 layers. This may suffice to induce height selection during film growth. Scanning STM analysis has revealed remarkable flat-topped or mesa-like island and film morphologies in various systems. We discuss in detail observations of QSE and associated film growth behavior for Pb/Cu(111, Ag/Fe(100, and Cu/fcc-Fe/Cu(100 [A/B or A/B/A], and for Ag/NiAl(110 with brief comments offered for Fe/Cu3Au(001 [A/BC binary alloys]. We also describe these issues for Ag/5-fold i-Al-Pd-Mn and Bi/5-fold i-Al-Cu-Fe [A/BCD ternary icosohedral quasicrystals]. Electronic structure theory analysis, either at the level of simple free electron gas models or more sophisticated Density Functional Theory calculations, can provide insight into the QSE-mediated thermodynamic driving force underlying height selection.

  2. Behavior of a SnLi liquid metal eutectic on D-irradiated, porous tungsten substrates

    Science.gov (United States)

    Lang, Eric; Kapat, Aveek; Allain, J. P.

    2016-10-01

    Tungsten (W) is a common PFC material in the divertor due to its beneficial thermomechanical properties and high sputter threshold. Under helium irradiation, W develops surface morphology such as fuzz. Liquid metals, such as tin-lithium eutectics, have been proposed as PFCs to combat W erosion and allow for a self-healing surface. Tin-dominant eutectics have lower evaporation rates than pure lithium due to increased binding energies, yet exhibit decreased D retention and Li surface segregation. In prior experiments of SnLi coatings on fuzzy W substrates, the SnLi layer has been shown to protect underlying fuzz. Additionally, the liquid metal better adhered to a fuzzy surface than a smooth one. Fuzzy W samples have been coated with a 95 at.% SnLi eutectic and exposed to 250eV D ions at elevated temperatures and fluences of 1017 cm-2 . Experiments will be conducted in the IGNIS facility, a multi-functional, in-situ irradiation and characterization facility at the University of Illinois. In-situ XPS will be used to elucidate irradiation-driven liquid metal behavior to identify surface chemistry changes. Additionally, ex-situSEM will be used to identify surface morphology changes. Work supported by US DOE Contract DE-SC0014267.

  3. Silver Nanowire Top Electrodes in Flexible Perovskite Solar Cells using Titanium Metal as Substrate.

    Science.gov (United States)

    Lee, Minoh; Ko, Yohan; Min, Byoung Koun; Jun, Yongseok

    2016-01-08

    Flexible perovskite solar cells (FPSCs) have various applications such as wearable electronic textiles and portable devices. In this work, we demonstrate FPSCs on a titanium metal substrate employing solution-processed silver nanowires (Ag NWs) as the top electrode. The Ag NW electrodes were deposited on top of the spiro-MeOTAD hole transport layer by a carefully controlled spray-coating method at moderate temperatures. The power conversion efficiency (PCE) reached 7.45 % under AM 1.5 100 mW cm(-2) illumination. Moreover, the efficiency for titanium-based FPSCs decreased only slightly (by 2.6 % of the initial value) after the devices were bent 100 times. With this and other advances, fully solution-based indium-free flexible photovoltaics, advantageous in terms of price and processing, have the potential to be scaled into commercial production. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Digital image processing of nanometer-size metal particles on amorphous substrates

    Science.gov (United States)

    Soria, F.; Artal, P.; Bescos, J.; Heinemann, K.

    1989-01-01

    The task of differentiating very small metal aggregates supported on amorphous films from the phase contrast image features inherently stemming from the support is extremely difficult in the nanometer particle size range. Digital image processing was employed to overcome some of the ambiguities in evaluating such micrographs. It was demonstrated that such processing allowed positive particle detection and a limited degree of statistical size analysis even for micrographs where by bare eye examination the distribution between particles and erroneous substrate features would seem highly ambiguous. The smallest size class detected for Pd/C samples peaks at 0.8 nm. This size class was found in various samples prepared under different evaporation conditions and it is concluded that these particles consist of 'a magic number' of 13 atoms and have cubooctahedral or icosahedral crystal structure.

  5. Comparison of interface structure of BCC metallic (Fe, V and Nb) films on MgO (100) substrate

    Energy Technology Data Exchange (ETDEWEB)

    Du, J.L. [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Zhang, L.Y. [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an, 710049 (China); Fu, E.G., E-mail: efu@pku.edu.cn [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Ding, X., E-mail: dingxd@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an, 710049 (China); Yu, K.Y., E-mail: kyyu@cup.edu.cn [Department of Materials Science and Engineering, China University of Petroleum, Beijing 102249 (China); Wang, Y.G. [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Wang, Y.Q.; Baldwin, J.K. [Experimental Physical Sciences Directorate, Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Wang, X.J. [State Key Laboratory of Advanced Optical Communication Systems and Networks, Peking University, Beijing 100871 (China); Xu, P. [Department of Chemistry, Harbin Institute of Technology, Harbin, Heilongjiang, 150001 (China)

    2017-07-15

    Highlights: • The difference of BCC metal/MgO(100) interface configuration with various lattice mismatches is identified by experiments and simulations in terms of dislocations and work of separation. • The strength of bonds along interface is found to be the fundamental factor to determine the interface configurations between BCC metal and MgO substrate. • The combination of experiments and simulations shows that the O-atop model is the actual match type between BCC metal and MgO substrate. - Abstract: This study systematically investigates the interface structure of three body-centered-cubic (BCC) metallic (Fe, V and Nb) films grown on MgO(100) substrates through experiments and simulations. Orientation relationships of their interfaces with the different lattice mismatches exhibit cube-on-cube configurations. The misfit dislocations at these three interfaces exhibit different characteristics. High resolution TEM (HRTEM), combined with first principle calculations, demonstrates the O-atop match type between metal atoms and MgO substrates for the first time. The fundamental mechanism in determining the interface configuration is discussed in terms of the work of separation and delocalization of atomic charge density.

  6. Synthesis and characterization of Cerium-doped hydroxyapatite/polylactic acid composite coatings on metal substrates

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Qiuhua, E-mail: yuanqiuh@szu.edu.cn; Qin, Caoping; Wu, Jianbo; Xu, Anping; Zhang, Ziqiang; Liao, Junquan; Lin, Songxin; Ren, Xiangzhong; Zhang, Peixin

    2016-10-01

    Ce-doped hydroxyapatite/polylactic acid (HA/PLA) composites serving as implant coatings have rarely been studied by other researchers in recent years. This paper was focused to study the existence of Ce ions in structure, chemical composition and surface morphology of HA and its composite coatings. Ce-doped HA powders were synthesized by chemical precipitation method with different Ce molar fractions (0(pure HA), 0.5 mol%, 1 mol% and 2 mol%). And Ce-doped HA/PLA composite coatings were fabricated for the first time on stainless steel substrates by spin coating technique. The obtained samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) coupled with energy dispersive X-ray detector (EDX), thermo gravimetric-differential thermal analysis (TG-DTA) and X-ray photoelectron spectroscopy (XPS). The results showed that Ce ions were doped into the crystal lattice of apatite successfully. The (Ce + Ca)/P atomic ratios in the doped HA/PLA samples ranged from 1.614 to 1.673, which were very close to the theoretical value of 1.67 for the stoichiometric HA. The addition of PLA could keep metal substrates from catalyzing the decomposition of HA. TG-DTA analysis indicated that Ce-doped HA powder had high thermal stability, and the SEM micrographs revealed that the surface topography of Ce-doped HA/PLA composite coatings was uniform and dense when the Ce molar fraction was 2 mol%. XPS results indicated that the Ce ions doped in HA showed mixed valences of Ce{sup 3+} and Ce{sup 4+}. - Highlights: • Ce-doped HA composite coatings were synthesized by spin-coating technique for the first time. • Ce ions were demonstrated to dope into HA crystal lattice successfully. • The addition of PLA could keep metal substrates from catalyzing the decomposition of HA. • XPS results showed that Ce ions doped in HA have mixed valences of Ce{sup 3+} and Ce{sup 4+}.

  7. CONTROLLED GROWTH OF CARBON NANOTUBES ON CONDUCTIVE METAL SUBSTRATES FOR ENERGY STORAGE APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Brown, P.; Engtrakul, C.

    2009-01-01

    The impressive mechanical and electronic properties of carbon nanotubes (CNTs) make them ideally suited for use in a variety of nanostructured devices, especially in the realm of energy production and storage. In particular, vertically-aligned CNT “forests” have been the focus of increasing investigation for use in supercapacitor electrodes and as hydrogen adsorption substrates. Vertically-aligned CNT growth was attempted on metal substrates by waterassisted chemical vapor deposition (CVD). CNT growth was catalyzed by iron-molybdenum (FeMo) nanoparticle catalysts synthesized by a colloidal method, which were then spin-coated onto Inconel® foils. The substrates were loaded into a custom-built CVD apparatus, where CNT growth was initiated by heating the substrates to 750 °C under the fl ow of He, H2, C2H4 and a controlled amount of water vapor. The resultant CNTs were characterized by a variety of methods including Raman spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM), and the growth parameters were varied in an attempt to optimize the purity and growth yield of the CNTs. The surface area and hydrogen adsorption characteristics of the CNTs were quantifi ed by the Brunauer- Emmett-Teller (BET) and Sieverts methods, and their capacitance was measured via cyclic voltammetry. While vertically-aligned CNT growth could not be verifi ed, TEM and SEM analysis indicated that CNT growth was still obtained, resulting in multiwalled CNTs of a wide range in diameter along with some amorphous carbon impurities. These microscopy fi ndings were reinforced by Raman spectroscopy, which resulted in a G/D ratio ranging from 1.5 to 3 across different samples, suggestive of multiwalled CNTs. Changes in gas fl ow rates and water concentration during CNT growth were not found to have a discernable effect on the purity of the CNTs. The specifi c capacitance of a CNT/FeMo/Inconel® electrode was found to be 3.2 F/g, and the BET surface area of

  8. Microtransfer printing of metal ink patterns onto plastic substrates utilizing an adhesion-controlled polymeric donor layer

    Science.gov (United States)

    Park, Ji-Sub; Choi, Jun-Chan; Park, Min-Kyu; Bae, Jeong Min; Bae, Jin-Hyuk; Kim, Hak-Rin

    2016-06-01

    We propose a method for transfer-printed electrode patterns onto flexible/plastic substrates, specifically intended for metal ink that requires a high sintering temperature. Typically, metal-ink-based electrodes cannot be picked up for microtransfer printing because the adhesion between the electrodes and the donor substrate greatly increases after the sintering process due to the binding materials. We introduced a polymeric donor layer between the printed electrodes and the donor substrate and effectively reduced the adhesion between the Ag pattern and the polymeric donor layer by controlling the interfacial contact area. After completing a wet-etching process for the polymeric donor layer, we obtained Ag patterns supported on the fine polymeric anchor structures; the Ag patterns could be picked up onto the stamp surface even after the sintering process by utilizing the viscoelastic properties of the elastomeric stamp with a pick-up velocity control. The proposed method enables highly conductive metal-ink-based electrode patterns to be applied on thermally weak plastic substrates via an all-solution process. Metal electrodes transferred onto a film showed superior electrical and mechanical stability under the bending stress test required for use in printed flexible electronics.

  9. Recent advances and perspectives in analytical methodologies for monitoring the bioavailability of trace metals in environmental solid substrates

    DEFF Research Database (Denmark)

    Miró, Manuel; Hansen, Elo Harald

    2006-01-01

    In the last decades, researchers have realised that the impact of trace elements (TE) in environmental solid substrates on ecological systems and biota cannot be ascertained appropriately by means of total metal content measurements. Assessment of TE chemical forms, types of binding and reactivit...

  10. Buffer layers for coated conductors

    Science.gov (United States)

    Stan, Liliana [Los Alamos, NM; Jia, Quanxi [Los Alamos, NM; Foltyn, Stephen R [Los Alamos, NM

    2011-08-23

    A composite structure is provided including a base substrate, an IBAD oriented material upon the base substrate, and a cubic metal oxide material selected from the group consisting of rare earth zirconates and rare earth hafnates upon the IBAD oriented material. Additionally, an article is provided including a base substrate, an IBAD oriented material upon the base substrate, a cubic metal oxide material selected from the group consisting of rare earth zirconates and rare earth hafnates upon the IBAD oriented material, and a thick film upon the cubic metal oxide material. Finally, a superconducting article is provided including a base substrate, an IBAD oriented material upon the base substrate, a cubic metal oxide material selected from the group consisting of rare earth zirconates and rare earth hafnates upon the IBAD oriented material, and an yttrium barium copper oxide material upon the cubic metal oxide material.

  11. The effect of substrate orientation on the kinetics and thermodynamics of initial oxide-film growth on metals

    Energy Technology Data Exchange (ETDEWEB)

    Reichel, Friederike

    2007-11-19

    This thesis addresses the effect of the parent metal-substrate orientation on the thermodynamics and kinetics of ultra-thin oxide-film growth on bare metals upon their exposure to oxygen gas at low temperatures (up to 650 K). A model description has been developed to predict the thermodynamically stable microstructure of a thin oxide film grown on its bare metal substrate as function of the oxidation conditions and the substrate orientation. For Mg and Ni, the critical oxide-film thickness is less than 1 oxide monolayer and therefore the initial development of an amorphous oxide phase on these metal substrates is unlikely. Finally, for Cu and densely packed Cr and Fe metal surfaces, oxide overgrowth is predicted to proceed by the direct formation and growth of a crystalline oxide phase. Further, polished Al single-crystals with {l_brace}111{r_brace}, {l_brace}100{r_brace} and {l_brace}110{r_brace} surface orientations were introduced in an ultra-high vacuum system for specimen processing and analysis. After surface cleaning and annealing, the bare Al substrates have been oxidized by exposure to pure oxygen gas. During the oxidation, the oxide-film growth kinetics has been established by real-time in-situ spectroscopic ellipsometry. After the oxidation, the oxide-film microstructures were investigated by angle-resolved X-ray photoelectron spectroscopy and low energy electron diffraction. Finally, high-resolution transmission electron microscopic analysis was applied to study the microstructure and morphology of the grown oxide films on an atomic scale. (orig.)

  12. Fabrication of arrayed metallic nano-particles on a flexible substrate for inducing localized surface plasmon resonance.

    Science.gov (United States)

    Chen, Chun-Hung; Lee, Yung-Chun

    2013-02-11

    This paper presents a new method for fabricating periodic arrays of metallic nano-particles on flexible substrates. This method is based on metallic film contact transfer method and high-power pulsed laser annealing. Experiments have been carried out to produce arrayed metallic nano-particles oriented in a hexagonal pattern. The nano-particle size is 70 nm in diameter and the center-to-center pitch of the hexagonal array is 400 nm. Large-area patterning and fabrication of these arrayed nano-particles can be easily achieved up to an area size of few cm(2). Besides, composite or compounded metallic nano-particle arrays can also be produced using different metal materials. The localized surface plasmon resonance (LSPR) effects induced by the fabricated arrays of nano-particles are experimentally observed and quantitatively measured. Numerical simulation on these LPSR effects is performed and the simulation results are in good agreement with experimental data.

  13. Substrate Lattice-Guided Seed Formation Controls the Orientation of 2D Transition Metal Dichalcogenides

    KAUST Repository

    Aljarb, Areej

    2017-08-07

    Two-dimensional (2D) transition metal dichalcogenide (TMDCs) semiconductors are important for next-generation electronics and optoelectronics. Given the difficulty in growing large single crystals of 2D TMDC materials, understanding the factors affecting the seed formation and orientation becomes an important issue for controlling the growth. Here, we systematically study the growth of molybdenum disulfide (MoS2) monolayer on c-plane sapphire with chemical vapor deposition (CVD) to discover the factors controlling their orientation. We show that the concentration of precursors, i.e., the ratio between sulfur and molybdenum oxide (MoO3), plays a key role in the size and orientation of seeds, subsequently controlling the orientation of MoS2 monolayers. High S/MoO3 ratio is needed in the early stage of growth to form small seeds that can align easily to the substrate lattice structures while the ratio should be decreased to enlarge the size of the monolayer at the next stage of the lateral growth. Moreover, we show that the seeds are actually crystalline MoS2 layers as revealed by high-resolution transmission electron microscopy. There exist two preferred orientations (0° or 60°) registered on sapphire, confirmed by our density functional theory (DFT) simulation. This report offers a facile technique to grow highly aligned 2D TMDCs and contributes to knowledge advancement in growth mechanism.

  14. Study of polymorphism using patterned self-assembled monolayers approach on metal substrates

    Science.gov (United States)

    Quiñones, Rosalynn; Brown, Ryanne T.; Searls, Noah; Richards-Waugh, Lauren

    2018-01-01

    Polymorphism is a molecule's ability to possess altered physical crystalline structures and has become an active interest in pharmaceuticals due to its ability to influence a drug's physical and chemical properties. Crystal stability and solubility are crucial in determining a drug's pharmacokinetics and pharmacodynamics. Changes in these properties due to polymorphisms have contributed to recalls and modifications in industrial production. For this study, the effects of surface interactions with pharmaceuticals were examined through surface modification methodology using organic phosphonic and sulfonic acid self-assembled monolayers (SAMs) developed on a nickel or zinc oxide metal substrate. Drugs analyzed included carbamazepine, cimetidine, tolfenamic acid, and flufenamic acid. All drugs were thermodynamically applied to the reformed surface to aid in recrystallization. It was hypothesized and confirmed that intermolecular bonds, especially hydrogen bonds between the SAMs and pharmaceutical drugs, were the force that assisted in polymorph development. The study was successful in revealing multiple forms for each drug, including their commercial form and at least one additional form using micro FT-IR, Raman spectroscopy, and PXRD. Visual comparisons of crystal polymorphisms were performed with IR microscopy.

  15. Oxidative damage to collagen and related substrates by metal ion/hydrogen peroxide systems

    DEFF Research Database (Denmark)

    Hawkins, C L; Davies, Michael Jonathan

    1997-01-01

    (II)-H2O2, evidence has been obtained for: i) altered sites of attack and fragmentation, ii) C-terminal decarboxylation, and iii) hydrogen abstraction at N-terminal alpha-carbon sites. This altered behaviour is believed to be due to the binding of copper ions to some substrates and hence site......'R"), and alpha-carbon[.C(R)(NH-)CO-,R = side-chain]radicals. Reaction with collagen gave both broad anisotropic signals, from high-molecular-weight protein-derived radicals, and isotropic signals from mobile species. The latter may be low-molecular-weight fragments, or mobile side-chain species; these signals...... are similar to those from the alpha-carbon site of peptides and the side-chain of lysine. Enzymatic digestion of the large, protein-derived, species releases similar low-molecular-weight adducts. The metal ion employed has a dramatic effect on the species observed. With Cu(I)-H2O2 or Cu(II)-H2O2 instead of Fe...

  16. Substrate-Based Noble-Metal Nanomaterials: Shape Engineering and Applications

    Science.gov (United States)

    Hajfathalian, Maryam

    Nanostructures have potential for use in state-of-the-art applications such as sensing, imaging, therapeutics, drug delivery, and electronics. The ability to fabricate and engineer these nanoscale materials is essential for the continued development of such devices. Because the morphological features of nanomaterials play a key role in determining chemical and physical properties, there is great interest in developing and improving methods capable of controlling their size, shape, and composition. While noble nanoparticles have opened the door to promising applications in fields such as imaging, cancer targeting, photothermal treatment, drug delivery, catalysis and sensing, the synthetic processes required to form these nanoparticles on surfaces are not well-developed. Herein is a detailed account on efforts for adapting established solution-based seed-mediated synthetic protocols to structure in a substrate-based platform. These syntheses start by (i) defining heteroepitaxially oriented nanostructured seeds at site-specific locations using lithographic or directed-assembly techniques, and then (ii) transforming the seeds using either a solution or vapor phase processing route to activate kinetically- or thermodynamically-driven growth modes, to arrive at nanocrystals with complex and useful geometries. The first series of investigations highlight synthesis-routes based on heterogeneous nucleation, where templates serve as nucleation sites for metal atoms arriving in the vapor phase. In the first research direction, the vapor-phase heterogeneous nucleation of Ag on Au was carried out at high temperatures, where the Ag vapor was sourced from a sublimating foil onto adjacent Au templates. This process transformed both the composition and morphology of the initial Au Wulff-shaped nanocrystals to a homogeneous AuAg nanoprism. In the second case, the vapor-phase heterogeneous nucleation of Cu atoms on Au nanocrystal templates was investigated by placing a Cu foil next

  17. Inkjet printing of multiple Ce{sub 0.8}Gd{sub 0.2}O{sub 2} buffer layers on a Ni-5%W substrate

    Energy Technology Data Exchange (ETDEWEB)

    Mosiadz, M; Tomov, R I; Hopkins, S C; Glowacki, B A [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Martin, G [Inkjet Research Centre, Institute for Manufacturing, Department of Engineering, University of Cambridge, Mill Lane, Cambridge, CB2 1RX (United Kingdom); Holzapfel, B, E-mail: mm701@cam.ac.u [Superconducting Materials, Institute for Metallic Materials, Leibnitz Institute for Solid State and Materials Research Dresden, Helmholtzstrasse 20, 01069 Dresden (Germany)

    2010-06-01

    The successful inkjet printing of multiple cerium gadolinium oxide (Ce{sub 0.8}Gd{sub 0.2}O{sub 2}) layers on highly textured Ni-5%W is reported using a stable ink, developing a solid-liquid interface comparable with that arising from dip coating. Two different approaches were used for the deposition of CGO layers using a 16-nozzle piezoelectric drop-on-demand print head. Two overlapping square arrays of droplets with constant volume and spacing were printed, with and without an intermediate CGO crystallization. The shortest possible heat treatment of the deposited layers was applied, potentially suitable for continuous large scale production. The results from X-ray diffraction show that the single phase Ce{sub 0.8}Gd{sub 0.2}O{sub 2} was obtained in all cases, but only the approach with intermediate CGO crystallization can produce a highly textured buffer layer. Optical micrographs and atomic force microscopy (AFM) also indicate the good quality of deposited films after heat treatment.

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

    Science.gov (United States)

    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.

  19. Modeling of metal nanocluster growth on patterned substrates and surface pattern formation under ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Numazawa, Satoshi

    2012-11-01

    This work addresses the metal nanocluster growth process on prepatterned substrates, the development of atomistic simulation method with respect to an acceleration of the atomistic transition states, and the continuum model of the ion-beam inducing semiconductor surface pattern formation mechanism. Experimentally, highly ordered Ag nanocluster structures have been grown on pre-patterned amorphous SiO{sub 2} surfaces by oblique angle physical vapor deposition at room temperature. Despite the small undulation of the rippled surface, the stripe-like Ag nanoclusters are very pronounced, reproducible and well-separated. The first topic is the investigation of this growth process with a continuum theoretical approach to the surface gas condensation as well as an atomistic cluster growth model. The atomistic simulation model is a lattice-based kinetic Monte-Carlo (KMC) method using a combination of a simplified inter-atomic potential and experimental transition barriers taken from the literature. An effective transition event classification method is introduced which allows a boost factor of several thousand compared to a traditional KMC approach, thus allowing experimental time scales to be modeled. The simulation predicts a low sticking probability for the arriving atoms, millisecond order lifetimes for single Ag monomers and {approx}1 nm square surface migration ranges of Ag monomers. The simulations give excellent reproduction of the experimentally observed nanocluster growth patterns. The second topic specifies the acceleration scheme utilized in the metallic cluster growth model. Concerning the atomistic movements, a classical harmonic transition state theory is considered and applied in discrete lattice cells with hierarchical transition levels. The model results in an effective reduction of KMC simulation steps by utilizing a classification scheme of transition levels for thermally activated atomistic diffusion processes. Thermally activated atomistic movements

  20. The Role of Interfacial Electronic Properties on Phonon Transport in Two-Dimensional MoS2 on Metal Substrates.

    Science.gov (United States)

    Yan, Zhequan; Chen, Liang; Yoon, Mina; Kumar, Satish

    2016-12-07

    We investigate the role of interfacial electronic properties on the phonon transport in two-dimensional MoS2 adsorbed on metal substrates (Au and Sc) using first-principles density functional theory and the atomistic Green's function method. Our study reveals that the different degree of orbital hybridization and electronic charge distribution between MoS2 and metal substrates play a significant role in determining the overall phonon-phonon coupling and phonon transmission. The charge transfer caused by the adsorption of MoS2 on Sc substrate can significantly weaken the Mo-S bond strength and change the phonon properties of MoS2, which result in a significant change in thermal boundary conductance (TBC) from one lattice-stacking configuration to another for same metallic substrate. In a lattice-stacking configuration of MoS2/Sc, weakening of the Mo-S bond strength due to charge redistribution results in decrease in the force constant between Mo and S atoms and substantial redistribution of phonon density of states to low-frequency region which affects overall phonon transmission leading to 60% decrease in TBC compared to another configuration of MoS2/Sc. Strong chemical coupling between MoS2 and the Sc substrate leads to a significantly (∼19 times) higher TBC than that of the weakly bound MoS2/Au system. Our findings demonstrate the inherent connection among the interfacial electronic structure, the phonon distribution, and TBC, which helps us understand the mechanism of phonon transport at the MoS2/metal interfaces. The results provide insights for the future design of MoS2-based electronics and a way of enhancing heat dissipation at the interfaces of MoS2-based nanoelectronic devices.

  1. Heavy metal leaching and environmental risk from the use of compost-like output as an energy crop growth substrate.

    Science.gov (United States)

    Page, K; Harbottle, M J; Cleall, P J; Hutchings, T R

    2014-07-15

    Conversion of productive agricultural land towards growth of energy crops has become increasingly controversial. Closed landfill sites represent significant areas of brownfield land, which have potential for the establishment of energy crops. Increasingly composts are now being produced from the degradable fraction of mixed municipal solid waste (MSW) and are commonly referred to as Compost-Like-Output (CLO). However, leaching of heavy metal and other elements due to the use of CLO as soil amendment has the potential to pose a risk to the wider environment as a diffuse pollution source if not managed correctly. Salix viminalis and Eucalyptus nitens were grown at 5 different CLO application rates (equivalent to 250, 1000, 3000, 6000, 1,0000 kg N/Ha) with weekly leachate analysis to assess the solubility of heavy metals and the potential release into the environment. The change in plant total dry mass suggested 3,000 kgN/Ha as the optimum application rate for both species. Weekly leachate analysis identified excess soluble ions within the first 4 weeks, with heavy metals concentrations exceeding water quality limits at the higher application rates (>3,000 kg N/Ha). Heavy metal uptake and accumulation within each species was also investigated; S. viminalis accumulated greater levels of heavy metals than E. nitens with a general trend of metal accumulation in root>stem>leaf material. Heavy metal leaching from soils amended with CLO has the potential to occur at neutral and slightly alkaline pH levels as a result of the high buffering capacity of CLO. The use of CLO at application rates of greater than 250 kg N/Ha may be limited to sites with leachate collection and containment systems, not solely for the heavy metal leaching but also excess nitrogen leaching. Alternatively lower application rates are required but will also limit biomass production. Copyright © 2014. Published by Elsevier B.V.

  2. Investigation of CeO2 Buffer Layer Effects on the Voltage Response of YBCO Transition-Edge Bolometers

    DEFF Research Database (Denmark)

    Mohajeri, Roya; Nazifi, Rana; Wulff, Anders Christian

    2016-01-01

    The effect on the thermal parameters of superconducting transition-edge bolometers produced on a single crystalline SrTiO3 (STO) substrate with and without a CeO2 buffer layer was investigated. Metal-organic deposition was used to deposit the 20-nm CeO2 buffer layer, whereas RF magnetron sputtering...... responses, and the results were compared with that of simulations conducted by applying a one-dimensional thermophysical model. It was observed that adding the buffer layer to the structure of the bolometer results in an increased response at higher modulation frequencies. Results from simulations made...

  3. Kinetic buffers.

    Science.gov (United States)

    Alibrandi, Giuseppe; Fabbrizzi, Luigi; Licchelli, Maurizio; Puglisi, Antonio

    2015-01-12

    This paper proposes a new type of molecular device that is able to act as an inverse proton sponge to slowly decrease the pH inside a reaction vessel. This makes the automatic monitoring of the concentration of pH-sensitive systems possible. The device is a composite formed of an alkyl chloride, which kinetically produces acidity, and a buffer that thermodynamically modulates the variation in pH value. Profiles of pH versus time (pH-t plots) have been generated under various experimental conditions by computer simulation, and the device has been tested by carrying out automatic spectrophotometric titrations, without using an autoburette. To underline the wide variety of possible applications, this new system has been used to realize and monitor HCl uptake by a di-copper(II) bistren complex in a single run, in a completely automatic experiment. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Development and characterization of a metallic substrat for nanostructured membranes in the separation of gas mixtures; Entwicklung und Charakterisierung eines metallischen Substrats fuer nanostrukturierte Gastrennmembranen

    Energy Technology Data Exchange (ETDEWEB)

    Brands, Katharina

    2010-07-01

    In order to minimize the further increase of CO{sub 2}-content in the atmosphere, efforts are made to separate and store CO{sub 2} from exhaust gases of fossil power plants. Beside well-established separation techniques like chemical scrubber, the application of membrane technology is intensively investigated. One focus of this thesis is the development of metal supported substrates for microporous ceramic gas separation membranes, which are expected to have a higher mechanical stability than ceramic supported substrates. Starting with commercial porous steel substrates, interlayers are applied by wet powder spraying. For the interlayers the materials 1.4404-stainless steel and TiO{sub 2} or 1.4845-stainless steel and yttria stabilized zirconia (8YSZ) are chosen. The interlayers have to be defect-free, as minimal defects can deteriorate the membrane performance. By a subsequent mechanical treatment and an adjustment of the viscosity of the 8YSZ-suspension, the surface quality is considerably increased. At the same time the limits of the wet powder spraying process become obvious, as sporadic agglomerates, which are formed during the spraying process, cannot be totally avoided. The metal supported substrates are characterized regarding to the interaction between steel and ceramic, the roughness of the layers compared to polished ceramic substrates, the mechanical properties and the flow through the substrates. Furthermore microporous ceramic gas separation membranes are deposited on wet powder sprayed and dip coated substrates. The selectivity of these membranes is above Knudsen selectivity. The other focus of the thesis is the exposure of substrates and membranes to real flue gas conditions. Beside microporous ceramic membranes polymer membranes are analysed as a reference, which show a higher state of development compared to microporous ceramic membranes. For this purpose a test bed is built up in the EnBW ''Rheinhafendampfkraftwerk RDK 7&apos

  5. Evaluation of the nanotube intrinsic resistance across the tip-carbon nanotube-metal substrate junction by Atomic Force Microscopy

    Science.gov (United States)

    2011-01-01

    Using an atomic force microscope (AFM) at a controlled contact force, we report the electrical signal response of multi-walled carbon nanotubes (MWCNTs) disposed on a golden thin film. In this investigation, we highlight first the theoretical calculation of the contact resistance between two types of conductive tips (metal-coated and doped diamond-coated), individual MWCNTs and golden substrate. We also propose a circuit analysis model to schematize the «tip-CNT-substrate» junction by means of a series-parallel resistance network. We estimate the contact resistance R of each contribution of the junction such as Rtip-CNT, RCNT-substrate and Rtip-substrate by using the Sharvin resistance model. Our final objective is thus to deduce the CNT intrinsic radial resistance taking into account the calculated electrical resistance values with the global resistance measured experimentally. An unwished electrochemical phenomenon at the tip apex has also been evidenced by performing measurements at different bias voltages with diamond tips. For negative tip-substrate bias, a systematic degradation in color and contrast of the electrical cartography occurs, consisting of an important and non-reversible increase of the measured resistance. This effect is attributed to the oxidation of some amorphous carbon areas scattered over the diamond layer covering the tip. For a direct polarization, the CNT and substrate surface can in turn be modified by an oxidation mechanism. PMID:21711904

  6. Epitaxial low-temperature growth of In0.5Ga0.5As films on GaAs(100) and GaAs(111) A substrates using a metamorphic buffer

    Science.gov (United States)

    Galiev, G. B.; Trunkin, I. N.; Klimov, E. A.; Klochkov, A. N.; Vasiliev, A. L.; Imamov, R. M.; Pushkarev, S. S.; Maltsev, P. P.

    2017-11-01

    A complex investigation of epitaxial In0.5Ga0.5As films grown on GaAs substrates with crystallographic orientations of (100) and (111) A in the standard high- and low-temperature modes has been performed. The parameters of the GaAs substrate and In0.5Ga0.5As film were matched using the technology of step-graded metamorphic buffer. The electrical and structural characteristics of the grown samples have been studied by the van der Pauw method, atomic force microscopy, scanning electron microscopy, and transmission/ scanning electron microscopy. The surface morphology is found to correlate with the sample growth temperature and doping with silicon. It is revealed that doping of low-temperature In0.5Ga0.5As layers with silicon significantly reduces both the surface roughness and highly improves the structural quality. Pores 50-100 nm in size are found in the low-temperature samples.

  7. Orientational control of CeO{sub 2} buffer layers on A-plane sapphire substrates for REBa{sub 2}Cu{sub 3}O{sub 7-{sigma}}thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sakuma, K., E-mail: t3308008@iwate-u.ac.j [Faculty of Engineering, Iwate University, 4-3-5 Ueda, Morioka-shi, Iwate 020-8551 (Japan); Michikami, O. [Faculty of Engineering, Iwate University, 4-3-5 Ueda, Morioka-shi, Iwate 020-8551 (Japan)

    2010-11-01

    We attempted the epitaxial growth of CeO{sub 2} on A-plane Al{sub 2}O{sub 3}(112-bar0) (A-Al{sub 2}O{sub 3}) substrates. As a buffer layers, CeO{sub 2} layers (CeO{sub 2}-I) were firstly prepared on A-Al{sub 2}O{sub 3} substrates at room temperature, and crystallized by ex situ annealing. The second CeO{sub 2} layers (CeO{sub 2}-II) were deposited on CeO{sub 2}-I. The thickness of CeO{sub 2}-I dependence of the characteristics of CeO{sub 2}-II and EuBa{sub 2}Cu{sub 3}O{sub 7-{sigma}}(EBCO) thin films, which were deposited on CeO{sub 2}-II, was investigated. The CeO{sub 2}-II layer completely was oriented along the c axis, while the in-plane orientation was not perfect. The critical current density (J{sub c}) decreased with degrading the in-plane orientation of EBCO thin films. It is found that the in-plane orientation of EBCO thin films greatly effected on J{sub c}. The best J{sub c} value at 77.3 K of EBCO thin films was 1.9 MA/cm{sup 2}.

  8. Epitaxial growth and dielectric properties of Bi sub 2 VO sub 5 sub . sub 5 thin films on TiN/Si substrates with SrTiO sub 3 buffer layers

    CERN Document Server

    Lee, H Y; Choi, B C; Jeong, J H; Joseph, M; Tabata, H; Kawai, T

    2000-01-01

    Bi sub 2 VO sub 5 sub . sub 5 (BVO) thin films were epitaxially grown on SrTiO sub 3 /TiN/Si substrates by using pulsed laser ablation. A TiN thin film was prepared at 700 .deg. C as a bottom electrode. The TiN film exhibited a high alpha axis orientation and a very smooth morphology. Before the preparation of the BVO thin film, a crystallized SrTiO sub 3 thin film was deposited as a buffer layer on TiN/Si. The BVO thin film grown at a substrate temperature at 700 .deg. C and an oxygen pressure of 50 mTorr was found to be epitaxial along the c-axis. Also, BVO films were observed to have flat surfaces and the step-flow modes. The dielectric constant of the BVO film on STO/TiN/Si was constant at about 8 approx 4 in the applied frequency range between 10 sup 2 and 10 sup 6 Hz.

  9. Determination of physical properties for β-TCP + chitosan biomaterial obtained on metallic 316L substrates

    Energy Technology Data Exchange (ETDEWEB)

    Mina, A. [Tribology, Powder Metallurgy and Processing of Solid Recycled Research Group, Universidad del Valle, Cali (Colombia); Tecno-Academia ASTIN SENA Reginal Valle (Colombia); Castaño, A. [Tribology, Powder Metallurgy and Processing of Solid Recycled Research Group, Universidad del Valle, Cali (Colombia); Caicedo, J.C., E-mail: julio.cesar.caicedo@correo.univalle.edu.co [Tribology, Powder Metallurgy and Processing of Solid Recycled Research Group, Universidad del Valle, Cali (Colombia); Caicedo, H.H. [Biologics Research, Biotechnology Center of Excellence, Janssen R& D, LLC, Pharmaceutical Companies of Johnson & Johnson, Spring House, PA 19477 (United States); National Biotechnology & Pharmaceutical Association, Chicago, IL 60606 (United States); Aguilar, Y. [Tribology, Powder Metallurgy and Processing of Solid Recycled Research Group, Universidad del Valle, Cali (Colombia)

    2015-06-15

    Material surface modification, particularly the deposition of special coatings on the surface of surgical implants, is extensively used in bone tissue engineering applications. β-Tricalcium phosphate/Chitosan (β-TCP/Ch) coatings were deposited on 316L stainless steel (316L SS) substrates by a cathodic electro-deposition technique at different coating compositions. The crystal lattice arrangements were analyzed by X-Ray diffraction (XRD), and the results indicated that the crystallographic structure of β-TCP was affected by the inclusion of the chitosan content. The changes in the surface morphology as a function of increasing chitosan in the coatings via scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that root-mean square values of the β-TCP/Ch coatings decreased by further increasing chitosan percentage. The elastic–plastic characteristics of the coatings were determined by conducting nanoindentation test, indicating that increase of chitosan percentage is directly related to increase of hardness and elastic modulus of the β-TCP/Ch coatings. Tribological characterization was performed by scratch test and pin-on-disk test to analyze the changes in the surface wear of β-TCP/Ch coatings. Finally, the results indicated an improvement in the mechanical and tribological properties of the β-TCP/Ch coatings as a function of increasing of the chitosan percentage. This new class of coatings, comprising the bioactive components, is expected not only to enhance the bioactivity and biocompatibility, but also to protect the surface of metallic implants against wear and corrosion. - Highlights: • Superficial phenomenon that occurs in tribological surface of β-tricalcium phosphate-chitosan coatings. • Improvement on surface mechanical properties of ceramic-polymeric and response to surface tribological damage. • β-tricalcium phosphate-chitosan coatings that offer highest performance in the biomedical devices.

  10. Chemically-modified graphene sheets as an active layer for eco-friendly metal electroplating on plastic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Joon-Suk; Hwang, Taeseon; Nam, Gi-Yong; Hong, Jung-Pyo [Department of Polymer Science and Engineering, Sungkyunkwan University, Chunchun-dong, Jangan-gu, Suwon, 440-746 (Korea, Republic of); Bae, Ah-Hyun; Son, Sang-Ik; Lee, Geun-Ho; Sung, Hak kyung [Manufacturing Tech. Center, Samsung Electronics Co., Ltd., Maetan-dong, Yeongtong-gu, Suwon, 443-742 (Korea, Republic of); Choi, Hyouk Ryeol; Koo, Ja Choon [School of Mechanical Engineering, Sungkyunkwan University, Suwon (Korea, Republic of); Nam, Jae-Do, E-mail: jdnam@skku.edu [Department of Polymer Science and Engineering, Sungkyunkwan University, Chunchun-dong, Jangan-gu, Suwon, 440-746 (Korea, Republic of); Department of Energy Science, Sungkyunkwan University, Suwon (Korea, Republic of)

    2012-10-30

    Eco-friendly nickel (Ni) electroplating was carried out on a plastic substrate using chemically modified graphene sheets as an active and conductive layer to initiate electroplating without using conventional pre-treatment or electroless metal-seeding processes. A graphene oxide (GO) solution was self-assembled on a polyethylene terephthalate (PET) film followed by evaporation to give GO layers (thickness around 6.5 {mu}m) on PET (GO/PET) film. Then, the GO/PET film was chemically and thermally reduced to convert the GO layers to reduced graphene oxide (RGO) layers on the PET substrate. The RGO-coated PET (RGO/PET) film showed the sheet resistance of 100 {Omega} per square. On RGO/PET film, Ni electroplating was conducted under the constant-current condition and the entire surface of the PET film was completely metalized with Ni without any voids.

  11. A facile metal-free "grafting-from" route from acrylamide-based substrate toward complex macromolecular combs

    KAUST Repository

    Zhao, Junpeng

    2013-01-01

    High-molecular-weight poly(N,N-dimethylacrylamide-co-acrylamide) was used as a model functional substrate to investigate phosphazene base (t-BuP 4)-promoted metal-free anionic graft polymerization utilizing primary amide moieties as initiating sites. The (co)polymerization of epoxides was proven to be effective, leading to macromolecular combs with side chains being single- or double-graft homopolymer, block copolymer and statistical copolymer. © 2013 The Royal Society of Chemistry.

  12. Noble metal nanoparticles on quartz supports as SERS substrates excited by a diode laser system for SERDS

    Science.gov (United States)

    Ossig, Robert; Kwon, Yong-Hyok; Kronfeldt, Heinz-Detlef; Träger, Frank; Hubenthal, Frank

    2012-03-01

    In this contribution we present surface enhanced Raman scattering (SERS) measurements of pyrene as a function of the surface plasmon resonance position of noble metal nanoparticle ensembles, which served as SERS substrates. The noble metal nanoparticle ensembles were prepared under ultrahigh vacuum (UHV) conditions by Volmer-Weber growth on quartz substrates. For the SERS measurements, the substrates were mounted in a flow-through cell as part of the optical Raman set-up. A diode laser microsystem with an emission wavelength of 488 nm was used. The system generates two slightly different emission wavelengths (Δλ ~ 0.3 nm) with a spectral width of ~ 10 pm and an optical power of ~ 10 mW. With this set-up SERS as well as shifted excitation Raman difference spectroscopy (SERDS) can be carried out. For trace analysis of pyrene in water SERS/SERDS experiments were accomplished as a function of molecule concentration and spectral position of the plasmon resonance. The best results with a limit of detection of 2 nmol of pyrene were obtained with a nanoparticle ensemble with a plasmon resonance in the vicinity of the excitation wavelength of λ = 488 nm. If the plasmon resonance frequency is slightly off-resonance the detection limit is significantly lower. The latter results are discussed in more detail and we will demonstrate that the morphology and the optical properties of the SERS substrates crucially influence the LOD.

  13. Molecular dynamics simulation of fabrication of Cu mono-component metallic glass by physical vapor deposition on Zr substrate

    CERN Document Server

    Yu, Yang; Cui, Fenping

    2016-01-01

    In this work, the single-component Cu metallic glass was fabricated by the physical vapor deposition on the Zr (0001) crystal substrate at 100 K using the classical molecular dynamic simulation. The same deposition process was performed on the Cu (1 0 0) and Ni (1 0 0) crystal substrate for comparison, only the Cu crystal deposited layer with the fcc structure can be obtained. When depositing the Cu atoms on the Zr substrate at 300 K, the crystal structure was formed, which indicates that except the suitable substrate, low temperature is also a key factor for the amorphous structure formation. The Cu liquid quenching from 2000 K to 100 K were also simulated with the cooling rate 1012 K/s to form the Cu glass film in this work. The Cu metallic glass from the two different processes (physical vapor deposition and rapid thermal quenching from liquid) revealed the same radial distribution function and X-ray diffraction pattern, but the different microstructure from the coordination number and Voronoi tessellation...

  14. The copper spoil heap Knappenberg, Austria, as a model for metal habitats – Vegetation, substrate and contamination

    Energy Technology Data Exchange (ETDEWEB)

    Adlassnig, Wolfram; Weiss, Yasmin S. [University of Vienna, Core Facility Cell Imaging and Ultrastructure Research, Althanstraße 14, A-1090 Vienna (Austria); Sassmann, Stefan [University of Vienna, Core Facility Cell Imaging and Ultrastructure Research, Althanstraße 14, A-1090 Vienna (Austria); University of Exeter, College of Life and Environmental Sciences, Biosciences, Stocker Road, Exeter EX4 4QD (United Kingdom); Steinhauser, Georg [Leibniz University Hannover, Institute of Radioecology and Radiation Protection, Herrenhäuser Straße 2, D30419 Hannover (Germany); Hofhansl, Florian [University of Vienna, Department of Microbiology and Ecosystem Science, Althanstraße 14, A-1090 Vienna (Austria); Instituto Nacional de Pesquisas da Amazônia, Coordenação de Dinâmica Ambiental, Manaus (Brazil); Baumann, Nils [Helmholtz-Zentrum Dresden-Rossendorf, Division of Biogeochemistry, Bautzner Landstraße 400, D-01328 Dresden (Germany); Lichtscheidl, Irene K. [University of Vienna, Core Facility Cell Imaging and Ultrastructure Research, Althanstraße 14, A-1090 Vienna (Austria); Lang, Ingeborg, E-mail: ingeborg.lang@univie.ac.at [University of Vienna, Core Facility Cell Imaging and Ultrastructure Research, Althanstraße 14, A-1090 Vienna (Austria)

    2016-09-01

    Historic mining in the Eastern Alps has left us with a legacy of numerous spoil heaps hosting specific, metal tolerant vegetation. Such habitats are characterized by elevated concentrations of toxic elements but also by high irradiation, a poorly developed substrate or extreme pH of the soil. This study investigates the distribution of vascular plants, mosses and lichens on a copper spoil heap on the ore bearing Knappenberg formed by Prebichl Layers and Werfener Schist in Lower Austria. It serves as a model for discriminating between various ecological traits and their effects on vegetation. Five distinct clusters were distinguished: (1) The bare, metal rich Central Spoil Heap was only colonised by highly resistant specialists. (2) The Northern and (3) Southern Peripheries contained less copper; the contrasting vegetation was best explained by the different microclimate. (4) A forest over acidic bedrock hosted a vegetation overlapping with the periphery of the spoil heap. (5) A forest over calcareous bedrock was similar to the spoil heap with regard to pH and humus content but hosted a vegetation differing strongly to all other habitats. Among the multiple toxic elements at the spoil heap, only Cu seems to exert a crucial influence on the vegetation pattern. Besides metal concentrations, irradiation, humidity, humus, pH and grain size distribution are important for the establishment of a metal tolerant vegetation. The difference between the species poor Northern and the diverse Southern Periphery can be explained by the microclimate rather than by the substrate. All plant species penetrating from the forest into the periphery of the spoil heap originate from the acidic but not from the calcareous bedrock. - Highlights: • Strong impact on plant diversity by isolation and extreme abiotic conditions • Both, microclimate and substrate explain species distribution. • Increased cellular metal tolerance of plants from the Central Spoil Heap • Among toxic elements

  15. High mobility single-crystalline-like GaAs thin films on inexpensive flexible metal substrates by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, P., E-mail: pdutta2@central.uh.edu; Rathi, M.; Gao, Y.; Yao, Y.; Selvamanickam, V. [Department of Mechanical Engineering, University of Houston, Houston, Texas 77204 (United States); Zheng, N.; Ahrenkiel, P. [Department of Nanoscience and Nanoengineering, South Dakota School of Mines and Technology, Rapid City, South Dakota 57701 (United States); Martinez, J. [Materials Evaluation Laboratory, NASA Johnson Space Center, Houston, Texas 77085 (United States)

    2014-09-01

    We demonstrate heteroepitaxial growth of single-crystalline-like n and p-type doped GaAs thin films on inexpensive, flexible, and light-weight metal foils by metal-organic chemical vapor deposition. Single-crystalline-like Ge thin film on biaxially textured templates made by ion beam assisted deposition on metal foil served as the epitaxy enabling substrate for GaAs growth. The GaAs films exhibited strong (004) preferred orientation, sharp in-plane texture, low grain misorientation, strong photoluminescence, and a defect density of ∼10{sup 7 }cm{sup −2}. Furthermore, the GaAs films exhibited hole and electron mobilities as high as 66 and 300 cm{sup 2}/V-s, respectively. High mobility single-crystalline-like GaAs thin films on inexpensive metal substrates can pave the path for roll-to-roll manufacturing of flexible III-V solar cells for the mainstream photovoltaics market.

  16. The Role of III-V Substrate Roughness and Deoxidation Induced by Digital Etch in Achieving Low Resistance Metal Contacts

    Directory of Open Access Journals (Sweden)

    Florent Ravaux

    2017-06-01

    Full Text Available To achieve low contact resistance between metal and III-V material, transmission-line-model (TLM structures of molybdenum (Mo were fabricated on indium phosphide (InP substrate on the top of an indium gallium arsenide (InGaAs layer grown by molecular beam epitaxy. The contact layer was prepared using a digital etch procedure before metal deposition. The contact resistivity was found to decrease significantly with the cleaning process. High Resolution Transmission & Scanning Electron Microscopy (HRTEM & HRSTEM investigations revealed that the surface roughness of treated samples was increased. Further analysis of the metal-semiconductor interface using Energy Electron Loss Spectroscopy (EELS showed that the amount of oxides (InxOy, GaxOy or AsxOy was significantly decreased for the etched samples. These results suggest that the low contact resistance obtained after digital etching is attributed to the combined effects of the induced surface roughness and oxides removal during the digital etch process.

  17. Influence of vicinal sapphire substrate on the properties of N-polar GaN films grown by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Zhiyu; Zhang, Jincheng, E-mail: jchzhang@xidian.edu.cn; Xu, Shengrui; Chen, Zhibin; Yang, Shuangyong; Tian, Kun; Hao, Yue [Key Lab of Wide Band-Gap Semiconductor Technology, School of Microelectronics, Xidian University, Xi' an, Shaanxi 710071 (China); Su, Xujun [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, Jiangsu 215123 (China); Shi, Xuefang [School of Advanced Materials and Nanotechnology, Xidian University, Xi' an, Shaanxi 710071 (China)

    2014-08-25

    The influence of vicinal sapphire substrates on the growth of N-polar GaN films by metal-organic chemical vapor deposition is investigated. Smooth GaN films without hexagonal surface feature are obtained on vicinal substrate. Transmission electron microscope results reveal that basal-plane stacking faults are formed in GaN on vicinal substrate, leading to a reduction in threading dislocation density. Furthermore, it has been found that there is a weaker yellow luminescence in GaN on vicinal substrate than that on (0001) substrate, which might be explained by the different trends of the carbon impurity incorporation.

  18. Investigation of the Matrix Effect on the Accuracy of Quantitative Analysis of Trace Metals in Liquids Using Laser-Induced Breakdown Spectroscopy with Solid Substrates.

    Science.gov (United States)

    Xiu, Junshan; Dong, Lili; Qin, Hua; Liu, Yunyan; Yu, Jin

    2016-12-01

    The detection limit of trace metals in liquids has been improved greatly by laser-induced breakdown spectroscopy (LIBS) using solid substrate. A paper substrate and a metallic substrate were used as a solid substrate for the detection of trace metals in aqueous solutions and viscous liquids (lubricating oils) respectively. The matrix effect on quantitative analysis of trace metals in two types of liquids was investigated. For trace metals in aqueous solutions using paper substrate, the calibration curves established for pure solutions and mixed solutions samples presented large variation on both the slope and the intercept for the Cu, Cd, and Cr. The matrix effects among the different elements in mixed solutions were observed. However, good agreement was obtained between the measured and known values in real wastewater. For trace metals in lubricating oils, the matrix effect between the different oils is relatively small and reasonably negligible under the conditions of our experiment. A universal calibration curve can be established for trace metals in different types of oils. The two approaches are verified that it is possible to develop a feasible and sensitive method with accuracy results for rapid detection of trace metals in industrial wastewater and viscous liquids by laser-induced breakdown spectroscopy. © The Author(s) 2016.

  19. Corrosion Control through a Better Understanding of the Metallic Substrate/Organic Coating/Interface.

    Science.gov (United States)

    1988-01-04

    43 --Ihe Effect of Alkali Metal Hydroxides on the Dissolu- tion Behavior of a Zinc Phosphate Conversion Coating on Steel and Pertinence to...WT71 -. .,, Effect of Alkali Metal Hydroxides on the Dissolution Behavior of a Zinc Phosphate Conversion Coating on Steel and % Pertinence to Cathodic...Effect of Alkali Metal Hydroxides on the Dissolution Behavior of a Zinc Phosphate Conversion Coating on Steel and Pertinence to Cathodic Delamination

  20. Stretchable array of metal nanodisks on a 3D sinusoidal wavy elastomeric substrate for frequency tunable plasmonics

    Science.gov (United States)

    Feng, Di; Zhang, Hui; Xu, Siyi; Tian, Limei; Song, Ningfang

    2017-03-01

    Metal nanostructures integrated with soft, elastomeric substrates provide an unusual platform with capabilities in plasmonic frequency tuning of mechanical strain. In this paper, we have prepared a tunable optical device, dense arrays of plasmonic nanodisks on a low-modulus, and high-elongation elastomeric substrate with a three-dimensional (3D) sinusoidal wavy, and their optical characteristics have been measured and analyzed in detail. Since surface plasmon is located and propagates along metal surfaces with sub-wavelength structures, and those dispersive properties are determined by the coupling strength between the individual structures, in this study, a 3D sinusoidal curve elastomeric substrate is used to mechanically control the inter-nanodisk spacing by applying straining and creating a frequency tunable plasmonic device. Here we study the optical resonance peak shifting generated by stretching this type of flexible device, and the role that 3D sinusoidal curve surface configuration plays in determining the tunable properties. Since only the hybrid dipolar mode has been observed in experiments, the coupled dipole approximation (CDA) method is employed to simulate the optical response of these devices, and the experimental and simulation results show that these devices have high tunability to shift optical resonance peaks at near-infrared wavelengths, which will provide strong potential for new soft optical sensors and wearable plasmonic sensors.

  1. Films of Transition Metal Complexes Including Ionic Liquids: Dramatic Effects of Processing Parameters and Substrate on the Film Morphology

    Science.gov (United States)

    Bayatpour, Sareh; Isik, Dilek; Santato, Clara

    2018-01-01

    Bis(2-phenylpyridine- C, N)(2,2'-bipyridine- N, N') iridium(III) hexafluorophosphate ([Ir(ppy)2(bpy)][PF6]) is an ionic transition-metal complex (iTMC) of interest for use in light-emitting electrochemical cells (LEECs). Films of [Ir(ppy)2(bpy)][PF6] blended with the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF6]), deposited on different substrates, have been investigated for their morphological features, which are expected to affect the functional properties of the films, e.g., charge carrier transport. In literature, ionic liquids have been included in films of transition-metal complexes (TMCs) to increase the ion mobility and improve the performance of LEECs. A systematic comparison between the morphology of pure [Ir(ppy)2(bpy)][PF6] films and [Ir(ppy)2(bpy)][PF6] films containing [BMIm][PF6] has been carried out on different types of substrate, namely Au-patterned SiO2, indium tin oxide (ITO), and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)-modified ITO. Although [Ir(ppy)2(bpy)][PF6] forms smooth films on SiO2, ITO, and PEDOT:PSS-modified ITO substrates, addition of [BMIm][PF6] caused formation of vertical, discontinuous aggregates, which are expected to be detrimental to charge transport in LEECs with planar architecture.

  2. How metal films de-wet substrates - identifying the kinetic pathways and energetic driving forces

    OpenAIRE

    McCarty, Kevin F.; Hamilton, John C.; Sato, Yu; Saa, Angela; Stumpf, Roland; De La Figuera, Juan; Thurmer, Konrad; Jones, Frank; Schmid, Andreas K.; Talin, A. Alec; Bartelt, Norman C.

    2009-01-01

    We study how single-crystal chromium films of uniform thickness on W(110) substrates are converted to arrays of three-dimensional (3D) Cr islands during annealing. We use low-energy electron microscopy (LEEM) to directly observe a kinetic pathway that produces trenches that expose the wetting layer. Adjacent film steps move simultaneously uphill and downhill relative to the staircase of atomic steps on the substrate. This step motion thickens the film regions where steps advance. Where film s...

  3. Effect of pH, various divalent metal ion and different substrates on ...

    African Journals Online (AJOL)

    The Michealis-Menten constant, Km and maximum velocity, Vmax obtained from Line-Weaver-Burk plot of initial velocity data at different substrate concentrations were 222 mg/ml and 500 μmol/min, 291 mg/ml and 1000 μmol/min, 137.5 mg/ml and 500 μmol/min using cassava, guinea corn and tiger nut starch as substrate, ...

  4. Designing and fabricating double resonance substrate with metallic nanoparticles-metallic grating coupling system for highly intensified surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Zhou, Ying; Li, Xuanhua; Ren, Xingang; Yang, Liangbao; Liu, Jinhuai

    2014-10-07

    Recently, nanoparticle-film coupling systems in which metal nanoparticles (supported localized surface plasmons, LSPs) are separated from a flat metal film (supported surface plasmon polaritons, SPPs) by a spacer have been widely reported due to its strong local enhancement field. However, there is are limited studies, which employ the design of combing metal grating into the nanoparticle-film gap system. Here, we propose and fabricate a novel double-resonance SERS system by strategically assembling Au NPs separated by a MoO3 nanospacer from an Ag grating film. The Ag grating with clear SPP effect is used for the first time in a double-resonance system, and the monolayer Au NPs array is well assembled onto the top of the Ag grating with a compact and uniform distribution (inter-particles gap of about 5 nm). As a result, we experimentally and theoretically demonstrate a significant near-field enhancement. The very strong near-field produced in the proposed SERS substrates is due to multiple couplings, including the Au NPs-Ag grating film coupling and Au NPs-Au NPs coupling. In addition, the as-proposed SERS substrates show good reproducibility of SERS, which have potential applications in plasmonic sensing and analytical science.

  5. EuBa 2Cu 3O 7 films grown on vicinal R-Al 2O 3 substrates with CeO 2 buffer layers by magnetron sputtering

    Science.gov (United States)

    Kimura, Y.; Michikami, O.; Fujiwara, S.; Sunagawa, K.; Yaguchi, Y.

    2008-09-01

    We deposited EuBa 2Cu 3O 7 (EBCO) films on vicinal R-Al 2O 3 substrates with CeO 2 buffer layers using DC magnetron sputtering. The influence of EBCO film thickness ( tEBCO) on surface morphology and superconducting properties of EBCO films was investigated in order to obtain high values of critical current density ( Jc) and Jc × tEBCO. By atomic force microscopy (AFM), the surface morphology of EBCO film was found to be porous and step-flow growth was observed. Micro-cracks began to occur above tEBCO = 5000 Å and increased as tEBCO increased. The critical temperature ( Tce) was constant at 91 K regardless of tEBCO. Jc and Jc × tEBCO showed high values of 4.67 MA/cm 2 and 140.1 A/cm at 77.3 K, respectively, when the tEBCO was 3000 Å.

  6. EuBa{sub 2}Cu{sub 3}O{sub 7} films grown on vicinal R-Al{sub 2}O{sub 3} substrates with CeO{sub 2} buffer layers by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Y. [Faculty of Engineering, Iwate University, 4-3-5 Ueda, Morioka-shi, Iwate 020-8551 (Japan)], E-mail: t5306002@iwate-u.ac.jp; Michikami, O.; Fujiwara, S. [Faculty of Engineering, Iwate University, 4-3-5 Ueda, Morioka-shi, Iwate 020-8551 (Japan); Sunagawa, K.; Yaguchi, Y. [NAMIKI Precision Jewel Co. Ltd., 3-8-22 Shinden, Adachi-ku, Tokyo 123-8511 (Japan)

    2008-09-15

    We deposited EuBa{sub 2}Cu{sub 3}O{sub 7} (EBCO) films on vicinal R-Al{sub 2}O{sub 3} substrates with CeO{sub 2} buffer layers using DC magnetron sputtering. The influence of EBCO film thickness (t{sub EBCO}) on surface morphology and superconducting properties of EBCO films was investigated in order to obtain high values of critical current density (J{sub c}) and J{sub c} x t{sub EBCO}. By atomic force microscopy (AFM), the surface morphology of EBCO film was found to be porous and step-flow growth was observed. Micro-cracks began to occur above t{sub EBCO} = 5000 A and increased as t{sub EBCO} increased. The critical temperature (T{sub ce}) was constant at 91 K regardless of t{sub EBCO}. J{sub c} and J{sub c} x t{sub EBCO} showed high values of 4.67 MA/cm{sup 2} and 140.1 A/cm at 77.3 K, respectively, when the t{sub EBCO} was 3000 A.

  7. Piezoelectric characterization of Pb(Zr,Ti)O3 thin films deposited on metal foil substrates by dip coating

    Science.gov (United States)

    Hida, Hirotaka; Hamamura, Tomohiro; Nishi, Takahito; Tan, Goon; Umegaki, Toshihito; Kanno, Isaku

    2017-10-01

    We fabricated the piezoelectric bimorphs composed of Pb(Zr,Ti)O3 (PZT) thin films on metal foil substrates. To efficiently inexpensively manufacture piezoelectric bimorphs with high flexibility, 1.2-µm-thick PZT thin films were directly deposited on both surfaces of 10- and 20-µm-thick bare stainless-steel (SS) foil substrates by dip coating with a sol-gel solution. We confirmed that the PZT thin films deposited on the SS foil substrates at 500 °C or above have polycrystalline perovskite structures and the measured relative dielectric constant and dielectric loss were 323-420 and 0.12-0.17, respectively. The PZT bimorphs were demonstrated by comparing the displacements of the cantilever specimens driven by single- and double-side PZT thin films on the SS foil substrates under the same applied voltage. We characterized the piezoelectric properties of the PZT bimorphs and the calculated their piezoelectric coefficient |e 31,f| to be 0.3-0.7 C/m2.

  8. Stress Corrosion Cracking Susceptibility of 304L Substrate and 308L Weld Metal Exposed to a Salt Spray

    Directory of Open Access Journals (Sweden)

    Chia-Hao Hsu

    2017-02-01

    Full Text Available 304 stainless steels (SS were considered as the materials for a dry storage canister. In this study, ER (Electrode Rod 308L was utilized as the filler metal for the groove and overlay welds of a 304L stainless steel substrate, which was prepared via a gas tungsten arc-welding process in multiple passes. The electron backscatter diffraction (EBSD map was used to identify the inherent microstructures in distinct specimens. U-bend and weight-loss tests were conducted by testing the 304L substrates and welds in a salt spray containing 5 wt % NaCl at 80 °C to evaluate their susceptibility to stress corrosion cracking (SCC. Generally, the weight loss of the ER 308L deposit was higher than that of the 304L substrate in a salt spray in the same sample-prepared condition. The dissolution of the skeletal structure in the fusion zone (FZ was responsible for a greater weight loss of the 308L deposit, especially for the cold-rolled and sensitized specimen. Cold rolling was detrimental and sensitization after cold rolling was very harmful to the SCC resistance of the 304L substrate and 308L deposit. Overall, the SCC susceptibility of each specimen was correlated with its weight loss in each group.

  9. Performance characterization of metallic substrates coated by HVOF WC–Co

    Energy Technology Data Exchange (ETDEWEB)

    Venter, Andrew M., E-mail: andrew.venter@necsa.co.za [Research and Development Division, Necsa Limited, Pretoria (South Africa); School of Chemical and Metallurgical Engineering, University of the Witwatersrand (South Africa); DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand (South Africa); Oladijo, O. Philip [School of Chemical and Metallurgical Engineering, University of the Witwatersrand (South Africa); DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand (South Africa); Luzin, Vladimir [ANSTO (Australian Nuclear Science and Technology Organisation), Lucas Height (Australia); Cornish, Lesley A.; Sacks, Natasha [School of Chemical and Metallurgical Engineering, University of the Witwatersrand (South Africa); DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand (South Africa)

    2013-12-31

    Integral to the performance of high-velocity oxygen-fuel (HVOF) coatings is the thermo-mechanical interaction associated with the thermal misfit, or differences in thermal expansion coefficients (CTEs), between coating and substrate. This investigation reports results on the microstructures, chemical phase content, coating–substrate misfit residual stress, and wear resistance. For this purpose a systematic characterization of WC–Co sprayed coatings on a number of substrates covering a range of CTE values were pursued for both the as-coated and heat-treated conditions. The neutron diffraction technique in conjunction with sub-millimeter sized gauge volumes enabled depth-resolved studies of the stress in the coatings and substrates by paying special attention to the determination of the stress contribution attributed by the final spray process. In the as-coated condition the stress values in the coatings were compressive for CTEs larger than that of WC–Co and tensile for CTE lower than WC–Co. Wear resistance increased for increased compressive stress and macrohardness. In the heat-treated condition, this trend became enhanced due to increased compressive stress in the coatings. - Highlights: • Four different substrate systems coated with HVOF WC-Co has been investigated. • Each substrate set encompassed the grit-blast surface and as-coated conditions, as well as their heat-treated counterparts. • Microstructural, macrohardness, wear performance and depth-resolved residual stress characterised. • Successful application of neutron strain scanning to investigating the combined systems, coatings and substrates. • Link observed between macrohardness, residual stress and wear performance.

  10. Investigation on electrically-driven semiconductor-metal transition of polycrystalline VO2 thin films on two kinds of substrates

    Directory of Open Access Journals (Sweden)

    Deen Gu

    2018-01-01

    Full Text Available Electrical driving is one of frequently-used stimuli for the semiconductor-metal transition (SMT of VO2. But the driving mechanism is still under debate. We investigated the DC electrically-driven SMT features of polycrystalline VO2 thin films deposited on two kinds of substrates (quartz and silicon with obviously-different thermal conductivity and the influence of cooling by a thermo electric cooler (TEC on the SMT of VO2. Interestingly, the SMT doesn’t happen at a high voltage at very start, but at a relatively low one. Moreover, the SMT of VO2 thin films on silicon substrate is completely restrained by cooling through a TEC although the electric field strength across VO2 reaches 1.1×107 V/m. Our findings reveal that the Joule-heating effect plays an important role in the DC electrically-driven SMT of VO2.

  11. High performance SERS on nanoporous gold substrates synthesized by chemical de-alloying a Au-based metallic glass

    Science.gov (United States)

    Xue, Yanpeng; Scaglione, Federico; Rizzi, Paola; Battezzati, Livio

    2017-12-01

    A Au20Cu48Ag7Pd5Si20 metallic glass precursor has been used to synthesize nanoporous gold by chemical de-alloying in a mixture of HNO3 and HF. Gold ligaments of size ranging from 45 to 100 nm were obtained as a function of HNO3 concentration, electrolyte temperature and de-alloying time. The as-prepared nanoporous gold exhibited strong surface enhanced Raman scattering (SERS) effect using 4,4‧-bi-pyridine as probe molecule. For application in melamine sensing, the detection limit of 10-6 M was achieved, which indicated that this biocompatible material has great potential as SERS active substrate.

  12. Structural study of ZnSe films grown on substrate with In{sub x}Ga{sub 1-x}As and Al{sub 1-x}Ga{sub x}As buffer layers: strain, relaxation and lattice parameter

    Energy Technology Data Exchange (ETDEWEB)

    Perez Ladron de Guevara, H.; Gaona-Couto, A.; Vidal, M.A. [Instituto de Investigacion En Comunicacion Optica (IICO), Universidad Autonoma de San Luis Potosi, San Luis Potosi (Mexico)]. E-mail: mavidal@cactus.iico.uaslp.mx; Luyo Alvarado, J.; Melendez Lira, M.; Lopez-Lopez, M. [Departamento de Fisica, Centro de Investigacion y Estudios Avanzados del IPN, Mexico DF (Mexico)

    2002-06-21

    ZnSe layers of various thickness were grown on (001) GaAs substrates, using In{sub x}Ga{sub 1-x}As or Al{sub 1-x}Ga{sub x}As as buffer layers by molecular beam epitaxy and were studied by high-resolution x-ray diffraction. The principal structural characteristics of ZnSe layer and buffer layer were determined using several reflections, such as (004) and two pairs of coupled asymmetric reflections, namely (224), (-2-24) and (115) (-1-15). In order to evaluate their validity, the experimental data obtained from these reflections were handled by means of two known expressions found in the literature. We have found the relaxation process of ZnSe layers is well described by a geometrical model including the thermal strain and small strain due to work hardening. The relaxation process is faster for ZnSe grown on ternary buffer layers despite the fact that, some buffer layers are pseudomorphically grown to the substrate; therefore we conclude that not only the lattice mismatches have effect on the relaxation process but also the surface state of the buffer layer has an influence in this process. (author)

  13. Investigation of laser metal deposited Alloy 718 onto an EN 1.4401 stainless steel substrate

    Science.gov (United States)

    Segerstark, Andreas; Andersson, Joel; Svensson, Lars-Erik

    2017-12-01

    This paper focuses on how process parameters affect the deposition of Alloy 718 onto an EN 1.4401 stainless steel substrate in terms of secondary phase formation, dilution and hardness. A columnar solidification structure with elongated grains growing in the direction normal to the substrate was observed for all parameters. In the interdendritic regions, phases with a high content of Niobium were identified. Scanning Electron Microscopy imaging and Energy Dispersive Spectroscopy measurements revealed these phases to most likely be Laves phase and Nb-carbides. Temperature measurements indicated no significant aging in the deposits. Considerable enrichment of iron was found in the initially deposited layers due to dilution from the substrate. The increased content of iron seemed to aid in forming constituents rich in niobium which, in turn, influenced the hardness. The highest mean hardness was noted in the sample with the lowest area fraction of Nb-rich constituents.

  14. The role of substrate electrons in the wetting of a metal surface

    OpenAIRE

    Schiros, T.; Takahashi, O.; Andersson, Klas Jerker; Ostrom, H.; Pettersson, L.G.M.; Nilsson, A.; Ogasawara, H.

    2010-01-01

    We address how the electronic and geometric structures of metal surfaces determine water-metal bonding by affecting the balance between Pauli repulsion and electrostatic attraction. We show how the rigid d-electrons and the softer s-electrons utilize different mechanisms for the redistribution of charge that enables surface wetting. On open d-shell Pt(111), the ligand field of water alters the distribution of metal d-electrons to reduce the repulsion. The closed-shell Cu d(10) configuration o...

  15. Protective conversion coating on mixed-metal substrates and methods thereof

    Energy Technology Data Exchange (ETDEWEB)

    O' Keefe, Matthew J.; Maddela, Surender

    2016-09-06

    Mixed-metal automotive vehicle bodies-in-white comprising ferrous metal surfaces, zinc surfaces, aluminum alloy surfaces, and magnesium alloy surfaces are cleaned and immersed in an aqueous bath comprising an adhesion promoter and an aqueous electrocoat bath (the adhesion promoter may be in the electrocoat bath. The adhesion promoter, which may be a cerium salt, is selected to react with each metal in the body surfaces to form an oxide layer that provides corrosion resistance for the surface and adherence for the deposited polymeric paint coating. The body is cathodic in the electrocoat deposition.

  16. Infrared-transmittance tunable metal-insulator conversion device with thin-film-transistor-type structure on a glass substrate

    Directory of Open Access Journals (Sweden)

    Takayoshi Katase

    2017-05-01

    Full Text Available Infrared (IR transmittance tunable metal-insulator conversion was demonstrated on a glass substrate by using thermochromic vanadium dioxide (VO2 as the active layer in a three-terminal thin-film-transistor-type device with water-infiltrated glass as the gate insulator. Alternative positive/negative gate-voltage applications induce the reversible protonation/deprotonation of a VO2 channel, and two-orders of magnitude modulation of sheet-resistance and 49% modulation of IR-transmittance were simultaneously demonstrated at room temperature by the metal-insulator phase conversion of VO2 in a non-volatile manner. The present device is operable by the room-temperature protonation in an all-solid-state structure, and thus it will provide a new gateway to future energy-saving technology as an advanced smart window.

  17. Direct Growth of CdTe on a (211) Si Substrate with Vapor Phase Epitaxy Using a Metallic Cd Source

    Science.gov (United States)

    Iso, Kenji; Gokudan, Yuya; Shiraishi, Masumi; Murakami, Hisashi; Koukitu, Akinori

    2017-10-01

    We successfully performed epitaxial CdTe growth on a Si (211) substrate with vapor-phase epitaxy using a cost-effective metallic cadmium source as a group-II precursor. The thermodynamic data demonstrate that the combination of metallic Cd and diisopropyl-telluride (DiPTe) with a H2 carrier gas enables the growth of CdTe crystals. A CdTe single crystal with a (422) surface orientation was obtained when a growth temperature between 600°C and 650°C was employed. The surface morphology and crystalline quality were improved with increasing film thickness. The full-width at half-maximum of the x-ray rocking curves with a film thickness of 15.7 μm for the skew-symmetrical (422) and asymmetrical (111) reflection were 528 arcsec and 615 arcsec, respectively.

  18. Growth of GaN on ZrB 2 substrate by metal-organic vapor phase epitaxy

    Science.gov (United States)

    Tomida, Yoshihito; Nitta, Shugo; Kamiyama, Satoshi; Amano, Hiroshi; Akasaki, Isamu; Otani, Shigeki; Kinoshita, Hiroyuki; Liu, Rong; Bell, Abigail; Ponce, Fernando A.

    2003-06-01

    Growth of GaN by metal-organic vapor phase epitaxy (MOVPE) on metallic zirconium diboride (ZrB 2) substrate was investigated. Cross-sectional transmission electron microscopy (TEM) showed that cubic ZrB xN 1- x is formed on the surface when ZrB 2 is exposed to ammonia-containing atmosphere, which protects the nucleation of GaN or AlN. We solved the problem by covering ZrB 2 surface with very thin AlN or GaN at low temperature, thereby achieving high-quality GaN growth with a dislocation density less than 10 8 cm -2. Direct conduction was achieved through the back of ZrB 2 and the surface of Si-doped GaN.

  19. Infrared-transmittance tunable metal-insulator conversion device with thin-film-transistor-type structure on a glass substrate

    Science.gov (United States)

    Katase, Takayoshi; Endo, Kenji; Ohta, Hiromichi

    2017-05-01

    Infrared (IR) transmittance tunable metal-insulator conversion was demonstrated on a glass substrate by using thermochromic vanadium dioxide (VO2) as the active layer in a three-terminal thin-film-transistor-type device with water-infiltrated glass as the gate insulator. Alternative positive/negative gate-voltage applications induce the reversible protonation/deprotonation of a VO2 channel, and two-orders of magnitude modulation of sheet-resistance and 49% modulation of IR-transmittance were simultaneously demonstrated at room temperature by the metal-insulator phase conversion of VO2 in a non-volatile manner. The present device is operable by the room-temperature protonation in an all-solid-state structure, and thus it will provide a new gateway to future energy-saving technology as an advanced smart window.

  20. Long range wetting transparency on top of layered metal dielectric substrates

    Science.gov (United States)

    2015-11-20

    thickness of the immediate substrate (IS: graphene in ref. 41 and MgF2 in our work), and US stands for underlying substrate ( copper in ref. 41 and...41, the wetting angle of water on top of one, two or three layers of graphene was the same or almost the same as that on top of underlying Au, Si...CO Environment and Film Thickness. Langmuir 23, 9785-9793 (2007). 41. Rafiee, J. et al. Wetting transparency of graphene . Nature Mater. 11, 217

  1. Wood-Reinforced Polyphthalamide Resins: MultiFunctional Composite Coating for Metal Substrates

    Directory of Open Access Journals (Sweden)

    M. Barletta

    2014-01-01

    Full Text Available Protective layers were deposited on aluminum substrates by dipping them inside a fluidized bed (FB of wood and polyphthalamide powders. The experimental investigation looked into the influence of the main process parameters (number and composition of superimposed layers, heating temperature, and dipping time on the visual appearance, scratch adhesion, wear resistance, and thermal insulation of the resulting coatings. Micromechanical and tribological responses of the coatings were significantly improved by the effect of the wooden particles dispersed inside the polyphthalamide binder. An improvement of the thermal insulation was also achieved whatever the setting of the process parameters. Further, the coatings displayed good adhesion to the substrate and wear endurance.

  2. Corrosion Control through a Better Understanding of the Metallic Substrate/Organic Coating/Interface.

    Science.gov (United States)

    1984-12-13

    of all species is enhanced. Third, it is probable that both anions and cations diffuse through the coating as aquo complexes which react differently to...the coating/metal interface looks promising as a water detection technique. This molecule upon reaction with ferrous ion yields a complex when dis...effective in promoting * bonding to titanium surfaces. *The interactions between metal surfaces and organic coatings are undoubtedly more complex than the

  3. Effect of pH, various divalent metal ion and different substrates on ...

    African Journals Online (AJOL)

    EZUGWU ARINZE LINUS

    Key words: Glucoamylase, pH, metal ions, Aspergillus niger, tiger nut starch, amylopectin. ... formation of a nucleophilic hydroxide ion at neutral pH by .... sodium acetate. Each of the reaction mixtures contains 0.5 ml of enzyme solution, 0.5 ml of starch solution (1%) and 1 ml of metal ion solutions (Ca2+, Mg2+, Mn2+, Fe2+, ...

  4. Long-range wetting transparency on top of layered metal-dielectric substrates

    National Research Council Canada - National Science Library

    Noginov, M A; Barnakov, Yuri A; Liberman, Vladimir; Prayakarao, Srujana; Bonner, Carl E; Narimanov, Evgenii E

    2016-01-01

    .... We have found that the wetting angle of water on top of MgF2 is highly sensitive to the thickness of the MgF2 layer and the nature of the underlying substrate that could be positioned as far as ~100...

  5. Investigation of photocatalytic activity of titanium dioxide deposited on metallic substrates by DC magnetron sputtering

    DEFF Research Database (Denmark)

    Daviðsdóttir, Svava; Canulescu, Stela; Dirscherl, Kai

    2013-01-01

    The photocatalytic properties of titanium dioxide (TiO2) coating in the anatase crystalline structure deposited on aluminium AA1050 alloy and stainless steel S316L substrates were investigated. The coating was prepared by DC magnetron sputtering. The microstructure and surface morphology of the c......The photocatalytic properties of titanium dioxide (TiO2) coating in the anatase crystalline structure deposited on aluminium AA1050 alloy and stainless steel S316L substrates were investigated. The coating was prepared by DC magnetron sputtering. The microstructure and surface morphology...... of the coating were investigated using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Glow Discharge Optical Emission Spectroscopy (GDOES), and X-Ray Diffraction (XRD). The photocatalytic behaviour was studied using electrochemical methods such as open circuit potential measurements, linear...... sweep voltammetry, impedance measurements. The microstructure and surface morphology of the coating were similar irrespective of the nature of the substrate, while the photocatalytic behaviour was found to vary depending on the substrate type. In general the TiO2 coating on stainless steel was shown...

  6. Nonlocal Screening of Plasmons in Graphene by Semiconducting and Metallic Substrates

    DEFF Research Database (Denmark)

    Yan, Jun; Thygesen, Kristian Sommer; Jacobsen, Karsten Wedel

    2011-01-01

    We investigate the role of substrates on the collective excitations of graphene by using a first-principles implementation of the density response function within the random-phase approximation. Specifically, we consider graphene adsorbed on SiC(0001) and Al(111) as representative examples of a s...

  7. The influence of metal ions on the substrate binding pocket of human alcohol dehydrogenase β 2β 2 by molecular modeling

    Science.gov (United States)

    Liu, Hsuan-Liang; Ho, Yih; Hsu, Chia-Ming

    2003-04-01

    Based on theoretical molecular modeling performed in this study, both structural and catalytic zinc ions, Zn s and Zn a, respectively, were shown to influence the structural integrity of the substrate binding pocket of human alcohol dehydrogenase β 2β 2 in the middle and outer regions. The replacement of both Zn s and Zn a with different metal ions restricts the access of bulky substrates to the bottom of the active site by narrowing the bottleneck formed between L116 and V294, whereas it does not affect substrate binding affinity since the accessible surface area of the substrate binding pocket remains more than 80% of the wild-type.

  8. Effects of metallic nanoparticle doped flux on the interfacial intermetallic compounds between lead-free solder ball and copper substrate

    Energy Technology Data Exchange (ETDEWEB)

    Sujan, G.K., E-mail: sgkumer@gmail.com; Haseeb, A.S.M.A., E-mail: haseeb@um.edu.my; Afifi, A.B.M., E-mail: amalina@um.edu.my

    2014-11-15

    Lead free solders currently in use are prone to develop thick interfacial intermetallic compound layers with rough morphology which are detrimental to the long term solder joint reliability. A novel method has been developed to control the morphology and growth of intermetallic compound layers between lead-free Sn–3.0Ag–0.5Cu solder ball and copper substrate by doping a water soluble flux with metallic nanoparticles. Four types of metallic nanoparticles (nickel, cobalt, molybdenum and titanium) were used to investigate their effects on the wetting behavior and interfacial microstructural evaluations after reflow. Nanoparticles were dispersed manually with a water soluble flux and the resulting nanoparticle doped flux was placed on copper substrate. Lead-free Sn–3.0Ag–0.5Cu solder balls of diameter 0.45 mm were placed on top of the flux and were reflowed at a peak temperature of 240 °C for 45 s. Angle of contact, wetting area and interfacial microstructure were studied by optical microscopy, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. It was observed that the angle of contact increased and wetting area decreased with the addition of cobalt, molybdenum and titanium nanoparticles to flux. On the other hand, wettability improved with the addition of nickel nanoparticles. Cross-sectional micrographs revealed that both nickel and cobalt nanoparticle doping transformed the morphology of Cu{sub 6}Sn{sub 5} from a typical scallop type to a planer one and reduced the intermetallic compound thickness under optimum condition. These effects were suggested to be related to in-situ interfacial alloying at the interface during reflow. The minimum amount of nanoparticles required to produce the planer morphology was found to be 0.1 wt.% for both nickel and cobalt. Molybdenum and titanium nanoparticles neither appear to undergo alloying during reflow nor have any influence at the solder/substrate interfacial reaction. Thus, doping

  9. Phytochelatin-metal(loid) transport into vacuoles shows different substrate preferences in barley and Arabidopsis.

    Science.gov (United States)

    Song, Won-Yong; Mendoza-Cózatl, David G; Lee, Youngsook; Schroeder, Julian I; Ahn, Sang-Nag; Lee, Hyun-Sook; Wicker, Thomas; Martinoia, Enrico

    2014-05-01

    Cadmium (Cd) and arsenic (As) are toxic to all living organisms, including plants and humans. In plants, Cd and As are detoxified by phytochelatins (PCs) and metal(loid)-chelating peptides and by sequestering PC-metal(loid) complexes in vacuoles. Consistent differences have been observed between As and Cd detoxification. Whereas chelation of Cd by PCs is largely sufficient to detoxify Cd, As-PC complexes must be sequestered into vacuoles to be fully detoxified. It is not clear whether this difference in detoxification pathways is ubiquitous among plants or varies across species. Here, we have conducted a PC transport study using vacuoles isolated from Arabidopsis and barley. Arabidopsis vacuoles accumulated low levels of PC2 -Cd, and vesicles from yeast cells expressing either AtABCC1 or AtABCC2 exhibited negligible PC2 -Cd transport activity compared with PC2 -As. In contrast, barley vacuoles readily accumulated comparable levels of PC2 -Cd and PC2 -As. PC transport in barley vacuoles was inhibited by vanadate, but not by ammonium, suggesting the involvement of ABC-type transporters. Interestingly, barley vacuoles exhibited enhanced PC2 transport activity when essential metal ions, such as Zn(II), Cu(II) and Mn(II), were added to the transport assay, suggesting that PCs might contribute to the homeostasis of essential metals and detoxification of non-essential toxic metal(loid)s. © 2013 John Wiley & Sons Ltd.

  10. Corrosion Monitoring of Flexible Metallic Substrates for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Trystan Watson

    2013-01-01

    Full Text Available Two techniques for monitoring corrosion within a dye-sensitized solar cell (DSC system are presented, which enable continuous, high sensitivity, in situ measurement of electrolyte breakdown associated with DSCs fabricated on metals. The first method uses UV/Vis reflectance spectrophotometry in conjunction with encapsulation cells, which incorporate a 25 μm thick electrolyte layer, to provide highly resolved triiodide absorption data. The second method uses digital image capture to extract colour intensity data. Whilst the two methods provide very similar kinetic data on corrosion, the photographic method has the advantage that it can be used to image multiple samples in large arrays for rapid screening and is also relatively low cost. This work shows that the triiodide electrolyte attacks most metals that might be used for structural applications. Even a corrosion resistant metal, such as aluminium, can be induced to corrode through surface abrasion. This result should be set in the context with the finding reported here that certain nitrogen containing heterocyclics used in the electrolyte to enhance performance also act as corrosion inhibitors with significant stabilization for metals such as iron. These new techniques will be important tools to help develop corrosion resistant metal surfaces and corrosion inhibiting electrolytes for use in industrial scale devices.

  11. Growth of ZnO nanowires through thermal oxidation of metallic zinc films on CdTe substrates

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, O., E-mail: oscar@fmc.uva.es [Optronlab Group, Dpto. Fisica Materia Condensada, Edificio I-D, Universidad de Valladolid, Paseo de Belen 1, 47011, Valladolid (Spain); Hortelano, V.; Jimenez, J. [Optronlab Group, Dpto. Fisica Materia Condensada, Edificio I-D, Universidad de Valladolid, Paseo de Belen 1, 47011, Valladolid (Spain); Plaza, J.L.; Dios, S. de; Olvera, J.; Dieguez, E. [Laboratorio de Crecimiento de Cristales, Departamento de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Fath, R.; Lozano, J.G.; Ben, T.; Gonzalez, D. [Dpto. Ciencia de los Materiales e Ingenieria Metalurgica y Q.I., Facultad de Ciencias, Apdo. 40, 11510 Puerto Real, Cadiz (Spain); Mass, J. [Dpto. de Fisica, Universidad del Norte, Km.5 Via Puerto Colombia, Barranquilla (Colombia)

    2011-04-28

    Research highlights: > ZnO nanowires grown from thermal Zn oxidation. > TEM reveals high quality thin nanowires several microns long. > New phase formation at long oxidation time. > Good spectroscopic properties measured by Raman, Photo and Cathodoluminsecence spectroscopies. - Abstract: <112-bar 0> wurtzite ZnO nanowires (NWs) have been obtained by oxidizing in air at 500 deg. C thermally evaporated Zn metal films deposited onto CdTe substrates. The presence of Cd atoms from the substrate on the ZnO seeding layer and NWs seems to affect the growth of the NWs. The effects of the oxidation time on the structural and optical properties of the NWs are described in detail. It is shown that the NWs density decreases and their length increases when increasing the oxidation time. Thicker Zn layers result in thinner and longer ZnO NWs. Very long oxidation times also lead to the formation of a new CdO phase which is related to the partial destruction and quality reduction of the NWs. The possible process for ZnO NW formation on CdTe substrates is discussed.

  12. The role of substrate electrons in the wetting of a metal surface.

    Science.gov (United States)

    Schiros, T; Takahashi, O; Andersson, K J; Oström, H; Pettersson, L G M; Nilsson, A; Ogasawara, H

    2010-03-07

    We address how the electronic and geometric structures of metal surfaces determine water-metal bonding by affecting the balance between Pauli repulsion and electrostatic attraction. We show how the rigid d-electrons and the softer s-electrons utilize different mechanisms for the redistribution of charge that enables surface wetting. On open d-shell Pt(111), the ligand field of water alters the distribution of metal d-electrons to reduce the repulsion. The closed-shell Cu d(10) configuration of isostructural Cu(111), however, does not afford this mechanism, resulting in a hydrophobic surface and three-dimensional ice cluster formation. On the geometrically corrugated Cu(110) surface, however, charge depletion involving the mobile sp-electrons at atomic rows reduces the exchange repulsion sufficiently such that formation of a two-dimensional wetting layer is still favored in spite of the d(10) electronic configuration.

  13. The role of substrate electrons in the wetting of a metal surface

    DEFF Research Database (Denmark)

    Schiros, T.; Takahashi, O.; Andersson, Klas Jerker

    2010-01-01

    of charge that enables surface wetting. On open d-shell Pt(111), the ligand field of water alters the distribution of metal d-electrons to reduce the repulsion. The closed-shell Cu d(10) configuration of isostructural Cu(111), however, does not afford this mechanism, resulting in a hydrophobic surface......We address how the electronic and geometric structures of metal surfaces determine water-metal bonding by affecting the balance between Pauli repulsion and electrostatic attraction. We show how the rigid d-electrons and the softer s-electrons utilize different mechanisms for the redistribution...... and three-dimensional ice cluster formation. On the geometrically corrugated Cu(110) surface, however, charge depletion involving the mobile sp-electrons at atomic rows reduces the exchange repulsion sufficiently such that formation of a two-dimensional wetting layer is still favored in spite of the d(10...

  14. Quantum electron states and resonances in thin monocrystal layers of noble metals on W (110) substrate

    CERN Document Server

    Vyalykh, D V; Prudnikova, G V; Grigoriev, A Y; Starodubov, A G; Adamchuk, V K

    2002-01-01

    For the first time in monocrystal layers of gold, silver and copper formed at W (110) single crystal surface one observed experimentally electron states and resonances of s p-type. They resulted from spatial localization of the Bloch type electron wave functions in quantum pit with potential barriers formed by vacuum/metal and metal/W (110) interfaces. One applied photoelectron spectroscopy with angular resolution to investigate experimentally into quantization of an electron structure of a valence band in Au/W (110), Ag/W (110) and Cu/W (110) systems

  15. Cell response to nanocrystallized metallic substrates obtained through severe plastic deformation.

    Science.gov (United States)

    Bagherifard, Sara; Ghelichi, Ramin; Khademhosseini, Ali; Guagliano, Mario

    2014-06-11

    Cell-substrate interface is known to control the cell response and subsequent cell functions. Among the various biophysical signals, grain structure, which indicates the repeating arrangement of atoms in the material, has also proved to play a role of significant importance in mediating the cell activities. Moreover, refining the grain size through severe plastic deformation is known to provide the processed material with novel mechanical properties. The potential application of such advanced materials as biomedical implants has recently been evaluated by investigating the effect of different substrate grain sizes on a wide variety of cell activities. In this review, recent advances in biomedical applications of severe plastic deformation techniques are highlighted with special attention to the effect of the obtained nano/ultra-fine-grain size on cell-substrate interactions. Various severe plastic deformation techniques used for this purpose are discussed presenting a brief description of the mechanism for each process. The results obtained for each treatment on cell morphology, adhesion, proliferation, and differentiation, as well as the in vivo studies, are discussed. Finally, the advantages and challenges regarding the application of these techniques to produce multifunctional bio-implant materials are addressed.

  16. Application of carbohydrate polymers as corrosion inhibitors for metal substrates in different media: A review.

    Science.gov (United States)

    Umoren, Saviour A; Eduok, Ubong M

    2016-04-20

    Naturally occurring polysaccharides are biopolymers existing as products of biochemical processes in living systems. A wide variety of them have been employed for various material applications; as binders, coatings, drug delivery, corrosion inhibitors etc. This review describes the application of some green and benign carbohydrate biopolymers and their derivatives for inhibition of metal corrosion. Their modes and mechanisms of protection have also been described as directly related to their macromolecular weights, chemical composition and their unique molecular and electronic structures. For instance, cellulose and chitosan possess free amine and hydroxyl groups capable of metal ion chelation and their lone pairs of electrons are readily utilized for coordinate bonding at the metal/solution interface. Some of the carbohydrate polymers reviewed in this work are either pure or modified forms; their grafted systems and nanoparticle composites with multitude potentials for metal protection applications have also been highlighted. Few inhibitors grafted to introduce more compact structures with polar groups capable of increasing the total energy of the surface have also been mentioned. Exudate gums, carboxymethyl and hydroxyethyl cellulose, starch, pectin and pectates, substituted/modified chitosans, carrageenan, dextrin/cyclodextrins and alginates have been elaborately reviewed, including the effects of halide additives on their anticorrosion performances. Aspects of computational/theoretical approach to corrosion monitoring have been recommended for future studies. This non-experimental approach to corrosion could foster a better understanding of the corrosion inhibition processes by correlating actual inhibition mechanisms with molecular structures of these carbohydrate polymers. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Physical masking process for integrating micro metallic structures on polymer substrate

    DEFF Research Database (Denmark)

    Islam, Mohammad Aminul; Hansen, Hans Nørgaard

    2009-01-01

    Integration of micro metallic structures in polymer devices is a broad multi-disciplinary research field, consisting of various combinations of mechanical, chemical and physical fabrication methods. Each of the methods has its specific advantages and disadvantages. Some applications like surface ...

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

    Energy Technology Data Exchange (ETDEWEB)

    Latifi, Afrooz, E-mail: afroozlatifi@yahoo.com [Department of Biomaterials, Biomedical Engineering Faculty, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Imani, Mohammad [Novel Drug Delivery Systems Dept., Iran Polymer and Petrochemical Institute, P.O. Box 14965/115, Tehran (Iran, Islamic Republic of); Khorasani, Mohammad Taghi [Biomaterials Dept., Iran Polymer and Petrochemical Institute, P.O. Box 14965/159, Tehran (Iran, Islamic Republic of); Daliri Joupari, Morteza [Animal and Marine Biotechnology Dept., National Institute of Genetic Engineering and Biotechnology, P.O. Box 14965/161, Tehran (Iran, Islamic Republic of)

    2014-11-30

    Highlights: • Stainless steel 316L was surface modified by plasma surface oxidation (PSO) and silicone rubber (SR) coating. • On the PSO substrates, concentration of oxide species was increased ca. 2.5 times comparing to non-PSO substrates. • The surface wettability was improved to 12.5°, in terms of water contact angle, after PSO. • Adhesion strength of SR coating on the PSO substrates was improved by more than two times comparing to non-PSO ones. • After pull-off test, the fractured area patterns for SR coating were dependent on the type of surface modifications received. - Abstract: 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{sup −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.

  19. The effect of dielectric constants on noble metal/semiconductor SERS enhancement: FDTD simulation and experiment validation of Ag/Ge and Ag/Si substrates.

    Science.gov (United States)

    Wang, Tao; Zhang, Zhaoshun; Liao, Fan; Cai, Qian; Li, Yanqing; Lee, Shuit-Tong; Shao, Mingwang

    2014-02-11

    The finite-difference time-domain (FDTD) method was employed to simulate the electric field distribution for noble metal (Au or Ag)/semiconductor (Ge or Si) substrates. The simulation showed that noble metal/Ge had stronger SERS enhancement than noble metal/Si, which was mainly attributed to the different dielectric constants of semiconductors. In order to verify the simulation, Ag nanoparticles with the diameter of ca. 40 nm were grown on Ge or Si wafer (Ag/Ge or Ag/Si) and employed as surface-enhanced Raman scattering substrates to detect analytes in solution. The experiment demonstrated that both the two substrates exhibited excellent performance in the low concentration detection of Rhodamine 6G. Besides, the enhancement factor (1.3 × 10(9)) and relative standard deviation values (less than 11%) of Ag/Ge substrate were both better than those of Ag/Si (2.9 × 10(7) and less than 15%, respectively), which was consistent with the FDTD simulation. Moreover, Ag nanoparticles were grown in-situ on Ge substrate, which kept the nanoparticles from aggregation in the detection. To data, Ag/Ge substrates showed the best performance for their sensitivity and uniformity among the noble metal/semiconductor ones.

  20. Effect of metal/substrate interfaces on radio-frequency loss in superconducting coplanar waveguides

    Science.gov (United States)

    Wisbey, David S.; Gao, Jiansong; Vissers, Michael R.; da Silva, Fabio C. S.; Kline, Jeffrey S.; Vale, Leila; Pappas, David P.

    2010-11-01

    Microscopic two-level systems (TLSs) are known to contribute to loss in resonant superconducting microwave circuits. This loss increases at low power and temperatures as the TLSs become unsaturated. We find that the loss is dependent on both the substrate-superconductor interface and the roughness of the surfaces. A native, oxide-free interface reduced the loss due to TLSs. However, a rough surface in the CPW gap did not cause more TLS loss, but the overall loss was significantly increased for the roughest surfaces.

  1. Structural and dynamic studies of substrate binding in porous metal-organic frameworks

    OpenAIRE

    Easun, Timothy; Moreau, Florian; Yan, Yong; Yang, Sihai; Schröder, Martin

    2016-01-01

    Porous metal–organic frameworks (MOFs) are the subject of considerable research interest because of\\ud their high porosity and capability of specific binding to small molecules, thus underpinning a wide range\\ud of materials functions such as gas adsorption, separation, drug delivery, catalysis, and sensing. MOFs,\\ud constructed by the designed assembly of metal ions and functional organic linkers, are an emerging class\\ud of porous materials with extended porous structures containing periodi...

  2. Effect of ZnO buffer layer on phase transition properties of vanadium dioxide thin films

    Science.gov (United States)

    Zhu, Huiqun; Li, Lekang; Li, Chunbo

    2016-03-01

    VO2 thin films were prepared on ZnO buffer layers by DC magnetron sputtering at room temperature using vanadium target and post annealing at 400 °C. The ZnO buffer layers with different thickness deposited on glass substrates by magnetron sputtering have a high visible and near infrared optical transmittance. The electrical resistivity and the phase transition properties of the VO2/ZnO composite thin films in terms of temperature were investigated. The results showed that the resistivity variation of VO2 thin film with ZnO buffer layer deposited for 35 min was 16 KΩ-cm. The VO2/ZnO composite thin films exhibit a reversible semiconductor-metal phase transition at 48 °C.

  3. Theoretical simulations of atomic and polyatomic bombardment of an organic overlayer on a metallic substrate

    CERN Document Server

    Krantzman, K D; Delcorte, A; Garrison, B J

    2003-01-01

    Our previous molecular dynamics simulations on initial test systems have laid the foundation for understanding some of the effects of polyatomic bombardment. In this paper, we describe simulations of the bombardment of a more realistic model system, an overlayer of sec-butyl-terminated polystyrene tetramers on a Ag left brace 1 1 1 right brace substrate. We have used this model system to study the bombardment with Xe and SF sub 5 projectiles at kinetic energies ranging from 0.50 to 5.0 keV. SF sub 5 sputters more molecules than Xe, but a higher percentage of these are damaged rather than ejected intact when the bombarding energy is greater than 0.50 keV. Therefore, at energies comparable to experimental values, the efficiency, measured as the yield-to-damage ratio, is greater with Xe than SF sub 5. Stable and intact molecules are generally produced by upward moving substrate atoms, while fragments are produced by the upward and lateral motion of reflected projectile atoms and fragments from the target molecul...

  4. 4 f occupancy and magnetism of rare-earth atoms adsorbed on metal substrates

    Science.gov (United States)

    Singha, Aparajita; Baltic, Romana; Donati, Fabio; Wäckerlin, Christian; Dreiser, Jan; Persichetti, Luca; Stepanow, Sebastian; Gambardella, Pietro; Rusponi, Stefano; Brune, Harald

    2017-12-01

    We report x-ray absorption spectroscopy and x-ray magnetic circular dichroism measurements as well as multiplet calculations for Dy, Ho, Er, and Tm atoms adsorbed on Pt(111), Cu(111), Ag(100), and Ag(111). In the gas phase, all four elements are divalent and we label their 4 f occupancy as 4 fn . Upon surface adsorption, and depending on the substrate, the atoms either remain in that state or become trivalent with 4 fn -1 configuration. The trivalent state is realized when the sum of the atomic correction energies (4 f →5 d promotion energy Ef d+ intershell coupling energy δ Ec ) is low and the surface binding energy is large. The latter correlates with a high substrate density of states at the Fermi level. The magnetocrystalline anisotropy of trivalent RE atoms is larger than the one of divalent RE atoms. We ascribe this to the significantly smaller covalent radius of the trivalent state compared to the divalent one for a given RE element. For a given valency of the RE atom, the anisotropy is determined by the overlap between the s p d states of the RE and the d states of the surface. For all investigated systems, the magnetization curves recorded at 2.5 K show absence of hysteresis indicating that magnetic relaxation is faster than about 10 s.

  5. Enhanced adhesion for LIGA microfabrication by using a buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Bajikar, Sateesh S.; DeCarlo, Francesco; Song, Joshua J.

    1998-05-22

    The present invention is an improvement on the LIGA microfabrication process wherein a buffer layer is applied to the upper or working surface of a substrate prior to the placement of a resist onto the surface of the substrate. The buffer layer is made from an inert low-Z material (low atomic weight), a material that absorbs secondary X-rays emissions from the substrate that are generated from the substrate upon exposure to a primary X-rays source. Suitable materials for the buffer layer include polyamides and polyimide. The preferred polyimide is synthesized from pyromellitic anhydride and oxydianiline (PMDA-ODA).

  6. Enhanced adhesion for LIGA microfabrication by using a buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Bajikar, Sateesh S.; De Carlo, Francesco; Song, Joshua J.

    2004-01-27

    The present invention is an improvement on the LIGA microfabrication process wherein a buffer layer is applied to the upper or working surface of a substrate prior to the placement of a resist onto the surface of the substrate. The buffer layer is made from an inert low-Z material (low atomic weight), a material that absorbs secondary X-rays emissions from the substrate that are generated from the substrate upon exposure to a primary X-rays source. Suitable materials for the buffer layer include polyamides and polyimide. The preferred polyimide is synthesized form pyromellitic anhydride and oxydianiline (PMDA-ODA).

  7. Enhanced adhesion for LIGA microfabrication by using a buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Bajikar, Sateesh S. (San Jose, CA); De Carlo, Francesco (Darien, IL); Song, Joshua J. (Naperville, IL)

    2001-01-01

    The present invention is an improvement on the LIGA microfabrication process wherein a buffer layer is applied to the upper or working surface of a substrate prior to the placement of a resist onto the surface of the substrate. The buffer layer is made from an inert low-Z material (low atomic weight), a material that absorbs secondary X-rays emissions from the substrate that are generated from the substrate upon exposure to a primary X-rays source. Suitable materials for the buffer layer include polyamides and polyimide. The preferred polyimide is synthesized form pyromellitic anhydride and oxydianiline (PMDA-ODA).

  8. Direct determination of monolayer MoS2 and WSe2 exciton binding energies on insulating and metallic substrates

    KAUST Repository

    Park, Soohyung

    2018-01-03

    Understanding the excitonic nature of excited states in two-dimensional (2D) transition-metal dichalcogenides (TMDCs) is of key importance to make use of their optical and charge transport properties in optoelectronic applications. We contribute to this by the direct experimental determination of the exciton binding energy (E b,exc) of monolayer MoS2 and WSe2 on two fundamentally different substrates, i.e. the insulator sapphire and the metal gold. By combining angle-resolved direct and inverse photoelectron spectroscopy we measure the electronic band gap (E g), and by reflectance measurements the optical excitonic band gap (E exc). The difference of these two energies is E b,exc. The values of E g and E b,exc are 2.11 eV and 240 meV for MoS2 on sapphire, and 1.89 eV and 240 meV for WSe2 on sapphire. On Au E b,exc is decreased to 90 meV and 140 meV for MoS2 and WSe2, respectively. The significant E b,exc reduction is primarily due to a reduction of E g resulting from enhanced screening by the metal, while E exc is barely decreased for the metal support. Energy level diagrams determined at the K-point of the 2D TMDCs Brillouin zone show that MoS2 has more p-type character on Au as compared to sapphire, while WSe2 appears close to intrinsic on both. These results demonstrate that the impact of the dielectric environment of 2D TMDCs is more pronounced for individual charge carriers than for a correlated electron–hole pair, i.e. the exciton. A proper dielectric surrounding design for such 2D semiconductors can therefore be used to facilitate superior optoelectronic device function.

  9. InAs/GaSb core-shell nanowires grown on Si substrates by metal-organic chemical vapor deposition

    Science.gov (United States)

    Ji, Xianghai; Yang, Xiaoguang; Du, Wenna; Pan, Huayong; Luo, Shuai; Ji, Haiming; Xu, Hongqi; Yang, Tao

    2017-06-01

    We report the growth of InAs/GaSb core-shell heterostructure nanowires with smooth sidewalls on Si substrates using metal-organic chemical vapor deposition (MOCVD) with no assistance from foreign catalysts. Sb adatoms were observed to strongly influence the morphology of the GaSb shell. In particular, Ga droplets form on the nanowire tips when a relatively low TMSb flow rate is used, whereas the droplets are missing and the radial growth of the GaSb is enhanced due to a reduction in the diffusion length of the Ga adatoms when the TMSb flow rate is increased. Moreover, transmission electron microscopy measurements revealed that the GaSb shell coherently grew on the InAs core without any misfit dislocations.

  10. Comparison of the columnar-thin-film and vacuum-metal-deposition techniques to develop sebaceous fingermarks on nonporous substrates.

    Science.gov (United States)

    Williams, Stephanie F; Pulsifer, Drew P; Shaler, Robert C; Ramotowski, Robert S; Brazelle, Shelly; Lakhtakia, Akhlesh

    2015-03-01

    Both the columnar-thin-film (CTF) and the vacuum-metal-deposition (VMD) techniques for visualizing sebaceous fingermarks require the deposition of a material thereon in a vacuum chamber. Despite that similarity, there are many differences between the two techniques. The film deposited with the CTF technique has a columnar morphology, but the film deposited with the VMD technique comprises discrete islands. A split-print methodology on a variety of fingermarked substrates was used to determine that the CTF technique is superior for developing fingermarks on clear sandwich bags and partial bloody fingermarks on stainless steel. Both techniques are similar in their ability to develop fingermarks on glass but the CTF technique yields higher contrast. The VMD technique is superior for developing fingermarks on white grocery bags and the smooth side of Gloss Finish Scotch Multitask(™) tape. Neither technique worked well for fingermarks on black garbage bags. © 2014 American Academy of Forensic Sciences.

  11. Synthesis of LaAlO3 by metal organic decomposition on SrTiO3 substrates

    Science.gov (United States)

    Ampuero, J. L.; Iliescu, I.; Boudard, M.; Jamaoui, A.; Rapenne, L.; Jimenez, C.; Roussel, H.

    2013-11-01

    LaAlO3 (LAO) films on SrTiO3 (STO) substrates have been produced by metal organic decomposition using La(C5H7O2)3 and Al(C5H7O2)3 as precursors dissolved in propionic acid. The process consists of growing thin layers through dip coating and subsequent annealing. After testing different cationic ratios of La and Al, it was determined that an optimal ratio leads to a single LAO phase film that grows epitaxially (cube on cube) on top of the STO. This was shown by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses. These analyses, as well as additional X-ray reflectivity analysis, also revealed that the LAO's thickness obtained in one dip ranges from 8 nm to 16 nm. Taking advantage of the epitaxial conditions, several layers can be stacked by successive dip coatings and annealing to form an epitaxial structure.

  12. Low Temperature Metal Free Growth of Graphene on Insulating Substrates by Plasma Assisted Chemical Vapor Deposition.

    Science.gov (United States)

    Muñoz, R; Munuera, C; Martínez, J I; Azpeitia, J; Gómez-Aleixandre, C; García-Hernández, M

    2017-03-01

    Direct growth of graphene films on dielectric substrates (quartz and silica) is reported, by means of remote electron cyclotron resonance plasma assisted chemical vapor deposition r-(ECR-CVD) at low temperature (650°C). Using a two step deposition process- nucleation and growth- by changing the partial pressure of the gas precursors at constant temperature, mostly monolayer continuous films, with grain sizes up to 500 nm are grown, exhibiting transmittance larger than 92% and sheet resistance as low as 900 Ω·sq-1. The grain size and nucleation density of the resulting graphene sheets can be controlled varying the deposition time and pressure. In additon, first-principles DFT-based calculations have been carried out in order to rationalize the oxygen reduction in the quartz surface experimentally observed. This method is easily scalable and avoids damaging and expensive transfer steps of graphene films, improving compatibility with current fabrication technologies.

  13. All-metal nanostructured substrates as subtractive color reflectors with near-perfect absorptance.

    Science.gov (United States)

    Ng, Ray J H; Goh, Xiao Ming; Yang, Joel K W

    2015-12-14

    All-metal structures consisting of nanoprotrusions on a bulk silver layer are theoretically investigated and shown to have narrow near-perfect absorption peaks (>95%). Within the constraints of constant nanostructure height (50 nm) and pitch (250 nm), these peaks are tunable across the visible spectrum by adjusting the width and shape of the protrusion. The peaks are caused by localized surface plasmon resonances leading to dissipation on the surface of the protrusions. As the peaks occur in the visible range, they produce subtractive colors with high saturation, in accordance with Schrödinger's rule for maximum pigment purity.

  14. Buffer Zone Fact Sheets

    Science.gov (United States)

    New requirements for buffer zones and sign posting contribute to soil fumigant mitigation and protection for workers and bystanders. The buffer provides distance between the pesticide application site and bystanders, reducing exposure risk.

  15. Design and production of a 2.5 kWe insulated metal substrate-based densely packed CPV assembly

    Science.gov (United States)

    Micheli, Leonardo; Sarmah, Nabin; Luo, Xichun; Reddy, K. S.; Mallick, Tapas K.

    2014-09-01

    The original design of a new 144-cell concentrating photovoltaic assembly is presented in this paper. It is conceived to work under 500 suns and to generate about 2.5 kWe. An insulated metal substrate was selected as baseplate, in order to get the best compromise between costs and thermal performances. It is based on a 2mm thick aluminum plate, which is in charge of removing the heat as quick as possible. The copper pattern and thickness has been designed accordingly to the IPC Generic Standard on Printed Board Design and to the restrictions of fit a reflective 125x primary optics and a 4x secondary refractive optics. The original outline of the conductive copper layer has been developed to minimize Joule losses by reducing the number of interconnections between the cells in series. Multijunction solar cells and Schottky bypass diodes have been soldered onto the board as surface mounted components. All the fabrication processes are described. This board represents a novelty for the innovative pattern of the conductive layer, which can be easily adapted to be coupled with different optics geometries and to allocate a different number of cells. The use of an IMS as baseplate will give an experimental contribution to the debate about the exploitability of this kind of substrates in CPV. This board is being characterized indoor and outdoor: the results will be used to improve the design and the reliability of the future receivers.

  16. Experimental studies on the effect of different metallic substrates on marine biofouling.

    Science.gov (United States)

    Vedaprakash, L; Dineshram, R; Ratnam, Krupa; Lakshmi, K; Jayaraj, K; Mahesh Babu, S; Venkatesan, R; Shanmugam, A

    2013-06-01

    In the wake of adoption of the resolution by the International Maritime Organization to control biofouling on vessels, which is recognized as a major vector for transfer of invasive species, this study attempts to create a baseline data on major hard-shelled biofouling organisms in the harbour waters. This study was primarily focused towards understanding the biofouling and corrosion pattern on various metals and their performance under immersed condition in a marine environment, at 0.3 and 3.0m depths. Furthermore, the study attempts to understand the surface dependent characteristics of barnacle base plate and its adhesion strength. Barnacle, mussels and oysters were the major fouling organisms accounting for 72.33% of the variation. Stainless steel and Titanium panels showed the highest average biofouling load of 176.36 and 168.35 g/300 cm(2), respectively. The variance in biofouling between metals and depths was highly significant at pshear of 6.86±0.95 kPa. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. All MOD buffer/YBCO approach to coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Parans Paranthaman, M. [Chemical Sciences Division, Oak Ridge National Laboratory, Building 4500 South, Room S-244, MS-6100, Oak Ridge, TN 37831-6100 (United States)]. E-mail: paranthamanm@ornl.gov; Sathyamurthy, S. [Chemical Sciences Division, Oak Ridge National Laboratory, Building 4500 South, Room S-244, MS-6100, Oak Ridge, TN 37831-6100 (United States); Heatherly, L. [Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6116 (United States); Martin, P.M. [Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6116 (United States); Goyal, A. [Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6116 (United States); Kodenkandath, T. [American Superconductor Corporation, Westborough, MA 01581 (United States); Li, X. [American Superconductor Corporation, Westborough, MA 01581 (United States); Thieme, C.L.H. [American Superconductor Corporation, Westborough, MA 01581 (United States); Rupich, M.W. [American Superconductor Corporation, Westborough, MA 01581 (United States)

    2006-10-01

    RABiTS based metal-organic deposition (MOD) buffer/YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) approach has been considered as one of the potential, low-cost approaches to fabricate high performance second generation coated conductors. The most commonly used RABiTS architectures consisting of a starting template of biaxially textured Ni-W (5 at.%) substrate with a seed layer of Y{sub 2}O{sub 3}, a barrier layer of YSZ, and a CeO{sub 2} cap. In this three layer architecture, all the buffers are deposited using physical vapor deposition (PVD) techniques. Using these PVD deposited templates, 0.8-{mu}m thick MOD-YBCO films with an I {sub c} (critical current) of 250 A/cm have been achieved routinely in short lengths. We have developed a low-cost, non-vacuum, MOD process to grow epitaxial buffer layers on textured Ni-5W substrates. The main challenge in this effort is to match the performance of MOD templates to that of PVD templates. We have recently shown that the properties of MOD-La{sub 2}Zr{sub 2}O{sub 7} (LZO) layers can be improved by inserting a thin Y{sub 2}O{sub 3} seed layer. Using MOD-CeO{sub 2} cap layers, we have demonstrated the growth of high performance MOD-YBCO films with an I {sub c} of 200 A/cm-width on MOD-La{sub 2}Zr{sub 2}O{sub 7}/Y{sub 2}O{sub 3}/Ni-5W substrates. This approach could potentially decrease the overall cost of the coated conductor fabrication.

  18. All MOD Buffer/YBCO Approach to Coated Conductors

    Energy Technology Data Exchange (ETDEWEB)

    Paranthaman, Mariappan Parans [ORNL; Sathyamurthy, Srivatsan [ORNL; Heatherly Jr, Lee [ORNL; Martin, Patrick M [ORNL; Goyal, Amit [ORNL; Kodenkandath, Thomas [American Superconductor Corporation, Westborough, MA; Li, Xiaoping [American Superconductor Corporation, Westborough, MA; Thieme, C. L. H. [American Superconductor Corporation, Westborough, MA; Rupich, Marty [American Superconductor Corporation, Westborough, MA

    2006-01-01

    RABiTS based metal-organic deposition (MOD) buffer/YBa2Cu3O7-d (YBCO) approach has been considered as one of the potential, low-cost approaches to fabricate high performance second generation coated conductors. The most commonly used RABiTS architectures consisting of a starting template of biaxially textured Ni-W (5 at.%) substrate with a seed layer of Y2O3, a barrier layer of YSZ, and a CeO2 cap. In this three layer architecture, all the buffers are deposited using physical vapor deposition (PVD) techniques. Using these PVD deposited templates, 0.8-{mu}m thick MOD-YBCO films with an Ic (critical current) of 250 A/cm have been achieved routinely in short lengths. We have developed a low-cost, non-vacuum, MOD process to grow epitaxial buffer layers on textured Ni-5W substrates. The main challenge in this effort is to match the performance of MOD templates to that of PVD templates. We have recently shown that the properties of MOD-La2Zr2O7 (LZO) layers can be improved by inserting a thin Y2O3 seed layer. Using MOD-CeO2 cap layers, we have demonstrated the growth of high performance MOD-YBCO films with an Ic of 200 A/cm-width on MOD-La2Zr2O7/Y2O3/Ni-5W substrates. This approach could potentially decrease the overall cost of the coated conductor fabrication.

  19. Growth of oriented rare-earth-transition-metal thin films

    Energy Technology Data Exchange (ETDEWEB)

    Fullerton, E.E.; Sowers, C.H.; Bader, S.D. [Argonne National Lab., IL (United States); Wu, X.Z. [Argonne National Lab., IL (United States)]|[Northern Illinois Univ., DeKalb, IL (United States)

    1996-04-01

    Rare-earth-transition-metal thin films are successfully grown by magnetron sputtering onto single-crystal MgO substrates with epitaxial W buffer layers. The use of epitaxial W buffer layers allows oriented single-phase films to be grown. Sm-Co films grown onto W(100), have strong in-plane anisotropy and coercivities exceeding 5 T at 5 K whereas Fe-Sm films have strong perpendicular anisotropy and are magnetically soft.

  20. Surface Decoration of Amino-Functionalized Metal-Organic Framework/Graphene Oxide Composite onto Polydopamine-Coated Membrane Substrate for Highly Efficient Heavy Metal Removal.

    Science.gov (United States)

    Rao, Zhuang; Feng, Kai; Tang, Beibei; Wu, Peiyi

    2017-01-25

    A new metal-organic framework/graphene oxide composite (IRMOF-3/GO) with high adsorption capacity of copper(II) (maximal adsorption amount = 254.14 mg/g at pH 5.0 and 25 °C) was prepared. Novel and highly efficient nanofiltration (NF) membrane can be facilely fabricated via surface decoration of IRMOF-3/GO onto polydopamine (PDA)-coated polysulfone (PSF) substrate. After decoration of IRMOF-3/GO, membrane surface potential increased from 6.7 to 13.1 mV at pH 5.0 and 25 °C. Due to the adsorption effect of IRMOF-3/GO and the enhancement of membrane surface potential, the prepared NF membrane (the loading amount of IRMOF-3/GO is ca. 13.6 g/m2) exhibits a highly efficient rejection of copper(II). The copper(II) rejection reaches up to ∼90%, while maintaining a relatively high flux of ∼31 L/m2/h at the pressure of 0.7 MPa and pH 5.0. Moreover, the membrane also presents an outstanding stability throughout the 2000 min NF testing period. Thus, the newly developed NF membrane shows a promising potential for water cleaning. This work provides a worthy reference for designing highly efficient NF membranes modified by metal-organic framework (MOF) relevant materials.

  1. Low dark current and high speed ZnO metal-semiconductor-metal photodetector on SiO2/Si substrate

    Science.gov (United States)

    ćalışkan, Deniz; Bütün, Bayram; ćakır, M. Cihan; Ã-zcan, Şadan; Ã-zbay, Ekmel

    2014-10-01

    ZnO thin films are deposited by radio-frequency magnetron sputtering on thermally grown SiO2 on Si substrates. Pt/Au contacts are fabricated by standard photolithography and lift-off in order to form a metal-semiconductor-metal (MSM) photodetector. The dark current of the photodetector is measured as 1 pA at 100 V bias, corresponding to 100 pA/cm2 current density. Spectral photoresponse measurement showed the usual spectral behavior and 0.35 A/W responsivity at a 100 V bias. The rise and fall times for the photocurrent are measured as 22 ps and 8 ns, respectively, which are the lowest values to date. Scanning electron microscope image shows high aspect ratio and dense grains indicating high surface area. Low dark current density and high speed response are attributed to high number of recombination centers due to film morphology, deducing from photoluminescence measurements. These results show that as deposited ZnO thin film MSM photodetectors can be used for the applications needed for low light level detection and fast operation.

  2. [Coating modification of anthracite substrates in vertical-flow constructed wetlands by LDHs synthesized from different metal compounds and the nitrogen removal efficiencies].

    Science.gov (United States)

    Zhang, Xiang-Ling; Guo, Lu; Chen, Jun-Jie; Liu, Xiao-Ting; Xu, Lu; Chen, Qiao-Zhen; Wang, Xiao-Xiao

    2014-08-01

    As one kind of vertical-flow constructed wetlands substrates, anthracite was selected in this experiment. LDHs (layered double hydroxides) were synthesized in alkaline conditions by co-precipitation of different kinds of metal compounds, such as CaCl2, ZnCl2, MgCl2, FeCl3, AlCl3, CoCl3. The synthesized LDHs were in-situ coated onto the surface of anthracite substrate to achieve the aim of modification. Simulated test columns were constructed to study the nitrogen removal efficiency of the urban sewage using the original anthracite substrates and 9 kinds of modified anthracite substrates. The results showed that: LDHs synthesized by all the 9 different kinds of methods could effectively modify the anthracite substrate by in-situ coating. With Mg2+ involved in the synthesis of modified substrates, good TN and ammonia nitrogen removal efficiencies were observed. The modified anthracite substrates coated with MgCo-LDHs had the optimal performance with average TN and ammonia nitrogen removal efficiencies of higher than 80% and 85%, respectively. The ammonia nitrogen removal efficiencies by the modified anthracite substrates coated by LDHs reacted with Mg2+ and Fe3+ were also high. The ammonia nitrogen removal efficiencies by modified anthracite substrates coated with CaFe-LDHs and MgFe-LDHs were higher than 85%.

  3. Copper-vapor-assisted chemical vapor deposition for high-quality and metal-free single-layer graphene on amorphous SiO2 substrate.

    Science.gov (United States)

    Kim, Hyungki; Song, Intek; Park, Chibeom; Son, Minhyeok; Hong, Misun; Kim, Youngwook; Kim, Jun Sung; Shin, Hyun-Joon; Baik, Jaeyoon; Choi, Hee Cheul

    2013-08-27

    We report that high-quality single-layer graphene (SLG) has been successfully synthesized directly on various dielectric substrates including amorphous SiO2/Si by a Cu-vapor-assisted chemical vapor deposition (CVD) process. The Cu vapors produced by the sublimation of Cu foil that is suspended above target substrates without physical contact catalyze the pyrolysis of methane gas and assist nucleation of graphene on the substrates. Raman spectra and mapping images reveal that the graphene formed on a SiO2/Si substrate is almost defect-free and homogeneous single layer. The overall quality of graphene grown by Cu-vapor-assisted CVD is comparable to that of the graphene grown by regular metal-catalyzed CVD on a Cu foil. While Cu vapor induces the nucleation and growth of SLG on an amorphous substrate, the resulting SLG is confirmed to be Cu-free by synchrotron X-ray photoelectron spectroscopy. The SLG grown by Cu-vapor-assisted CVD is fabricated into field effect transistor devices without transfer steps that are generally required when SLG is grown by regular CVD process on metal catalyst substrates. This method has overcome two important hurdles previously present when the catalyst-free CVD process is used for the growth of SLG on fused quartz and hexagonal boron nitride substrates, that is, high degree of structural defects and limited size of resulting graphene, respectively.

  4. Interaction of cw CO2 laser radiation with plasma near-metallic substrate surface

    Science.gov (United States)

    Azharonok, V. V.; Astapchik, S. A.; Zabelin, Alexandre M.; Golubev, Vladimir S.; Golubev, V. S.; Grezev, A. N.; Filatov, Igor V.; Chubrik, N. I.; Shimanovich, V. D.

    2000-07-01

    Optical and spectroscopic methods were used in studying near-surface plasma that is formed under the effect CW CO2 laser of (2- 5)x106W/cm2 power density upon stainless steel in He and Ar shielding gases. The variation of plume spatial structure with time has been studied, the outflow of gas-vapor jets from the interaction area has been characterized. The spectra of plasma plume pulsations have been obtained for the frequency range Δf = 0-1 MHz. The temperature and electron concentration of plasma plume have been found under radiation effect upon the target of stainless steel. Consideration has been given to the most probable mechanisms of CW laser radiation-metal non-stationary interaction.

  5. Fly ash based geopolymer thin coatings on metal substrates and its thermal evaluation.

    Science.gov (United States)

    Temuujin, Jadambaa; Minjigmaa, Amgalan; Rickard, William; Lee, Melissa; Williams, Iestyn; van Riessen, Arie

    2010-08-15

    Class F fly ash based Na-geopolymer formulations have been applied as fire resistant coatings on steel. The main variables for the coating formulations were Si: Al molar and water: cement weight ratios. We have determined that the adhesive strength of the coatings strongly depend on geopolymer composition. The ease with which geopolymer can be applied onto metal surfaces and the resultant thickness depend on the water content of the formulation. Adhesive strengths of greater than 3.5 MPa have been achieved on mild steel surfaces for compositions with Si:Al of 3.5. Microstructure evolution and thermal properties of the optimised coating formulations show that they have very promising fire resistant characteristics. Copyright 2010 Elsevier B.V. All rights reserved.

  6. Labview virtual instruments for calcium buffer calculations.

    Science.gov (United States)

    Reitz, Frederick B; Pollack, Gerald H

    2003-01-01

    Labview VIs based upon the calculator programs of Fabiato and Fabiato (J. Physiol. Paris 75 (1979) 463) are presented. The VIs comprise the necessary computations for the accurate preparation of multiple-metal buffers, for the back-calculation of buffer composition given known free metal concentrations and stability constants used, for the determination of free concentrations from a given buffer composition, and for the determination of apparent stability constants from absolute constants. As implemented, the VIs can concurrently account for up to three divalent metals, two monovalent metals and four ligands thereof, and the modular design of the VIs facilitates further extension of their capacity. As Labview VIs are inherently graphical, these VIs may serve as useful templates for those wishing to adapt this software to other platforms.

  7. Electrophoretic deposition of organic/inorganic composite coatings on metallic substrates for bone replacement applications: mechanisms and development of new bioactive materials based on polysaccharides

    OpenAIRE

    Cordero Arias, Luis Eduardo

    2015-01-01

    Regarding the need to improve the usually encountered osteointegration of metallic implants with the surrounding body tissue in bone replacement applications, bioactive organic/inorganic composite coatings on metallic substrates were developed in this work using electrophoretic deposition (EPD) as coating technology. In the present work three polysaccharides, namely alginate, chondroitin sulfate and chitosan were used as the organic part, acting as the matrix of the coating and enabling the c...

  8. Adsorption of water and ethanol on noble and transition-metal substrates: a density functional investigation within van der Waals corrections.

    Science.gov (United States)

    Freire, Rafael L H; Kiejna, Adam; Da Silva, Juarez L F

    2016-10-26

    We report the results of extensive computational investigation of the adsorption properties of water and ethanol on several Cu-, Pt-, and Au-based substrates, including the close-packed unreconstructed Cu(111), Pt(111), and Au(111) surfaces, defected metal substrates with on-surface low-coordinated sites generated by the intermixing of Pt-Cu and Pt-Au in the topmost surface layers and strained on-surface and sub-surface Pt-layers at Cu(111) and Au(111) substrates. The calculations are based on the density functional theory (DFT) within the van der Waals (vdW) correction. For all the substrates, we found that water and ethanol bind via the anionic O atom to the cationic one-fold coordinated on-top metal sites, which enhances the adsorbate-substrate Coulomb interactions. For water, both DFT and DFT + vdW calculations predict a flat geometry. For ethanol, the DFT and DFT + vdW results are in contrast, namely, DFT yields a perpendicular orientation of the C-C bond with respect to the surface, while we obtained a parallel orientation of the C-C bond using DFT + vdW, which maximizes the adsorption energies. Despite expected deviations due to the nature of the weak adsorbate-substrate interactions, we found that the adsorption energy of water and ethanol shows a linear dependence as a function of the position of the center of gravity of the occupied d-band, and hence, the magnitude of the adsorption energy increases as the d-band center position shifts towards the Fermi energy. Thus, it indicates hybridization between the O p- and metal d-states, which determines the magnitude of the adsorption energy of water and ethanol on clean, low-coordinated, and strained noble and transition-metal substrates.

  9. Effect of Adhesive Type on the Shear Bond Strength of Metal Brackets to Two Ceramic Substrates

    Directory of Open Access Journals (Sweden)

    Mohammad Sadegh Ahmad Akhoundi

    2014-04-01

    Full Text Available Increased number of adult patients requesting orthodontic treatment result in bonding bracket to ceramic restorations more than before. The aim of this study was to evaluate and compare the shear bond strength of orthodontic brackets bonded to two types of ceramic bases with conventional orthodontic bonding resin and a new nano-filled composite resin.Twenty four feldespathic porcelain and 24 lithium disilicate ceramic disks were fabricated. All of the samples were conditioned by sandblasting, hydrofluoric acid and silane. Maxillary incisor metal brackets were bonded to half of the disks in each group by conventional orthodontic bonding resin and the other half bonded with a nano-filled composite. The samples then were thermocycled for 2000 cycle between 5-55° C. Shear bond strength was measured and the mode of failure was examined. Randomly selected samples were also evaluated by SEM.The lowest bond strength value was found infeldespathic ceramic bonded by nano-filled composite (p<0.05. There was not any statistically significant difference between other groups regarding bond strength. The mode of failure in the all groups except group 1 was cohesive and porcelain damages were detected.Since less damages to feldspathic porcelain was observed when the nano-filled composite was used to bond brackets, the use of nano-filled composite resins can be suggested for bonding brackets to feldspathic porcelain restorations.

  10. Final report on LDRD project: Low-cost Pd-catalyzed metallization technology for rapid prototyping of electronic substrates and devices

    Energy Technology Data Exchange (ETDEWEB)

    Chen, K.S.; Morgan, W.P.; Zich, J.L.

    1998-02-01

    A low-cost, thermally-activated, palladium-catalyzed metallization process was developed for rapid prototyping of polymeric electronic substrates and devices. The process was successfully applied in producing adhesiveless copper/polyimide laminates with high peel strengths and thick copper coating; copper/polyimide laminates are widely used in fabricating interconnects such as printed wiring boards (PWBs) and flexible circuits. Also successfully metallized using this low-cost metallization process were: (1) scaled-down models of radar-and-communication antenna and waveguide; (2) scaled-down model of pulsed-power-accelerator electrode; (3) three-dimensional micro-porous, open-cell vitreous carbon foams. Moreover, additive patterned metallization was successfully achieved by selectively printing or plotting the catalyst ink only on areas where metallization is desired, and by uniform thermal activation. Additive patterned metallization eliminates the time-consuming, costly and environmentally-unfriendly etching process that is routinely carried out in conventional subtractive patterned metallization. A metallization process via ultraviolet (UV) irradiation activation was also demonstrated. In this process palladium-catalyst solution is first uniformly coated onto the substrate. A masking pattern is used to cover the areas where metallization is not wanted. UV irradiation is applied uniformly to activate the palladium catalyst and to cure the polymer carrier in areas that are not covered by the mask. Metal is then deposited by electroless plating only or by a combination of electroless and electrolytic plating. This UV-activation technique is particularly useful in additive fine-line patterned metallization. Lastly, computer models for electrolytic and electroless plating processes were developed to provide guidance in plating-process design.

  11. Study on advanced Ce0.9La0.1O2/Gd2Zr2O7 buffer layers architecture towards all chemical solution processed coated conductors

    DEFF Research Database (Denmark)

    Yue, Zhao; Ma, L.; Wu, W.

    2015-01-01

    2Zr2O7 buffer layer stack and the 200 nm thick YBa2Cu3O7 (YBCO) superconducting layer were sequentially deposited on textured NiW substrates using metal-organic deposition routes. The surface texture of the Gd2Zr2O7 barrier layer deteriorates when the film thickness increases to 80 nm, although...

  12. Semiconductor-Free Nonvolatile Resistive Switching Memory Devices Based on Metal Nanogaps Fabricated on Flexible Substrates via Adhesion Lithography

    KAUST Repository

    Semple, James

    2017-01-02

    Electronic memory cells are of critical importance in modern-day computing devices, including emerging technology sectors such as large-area printed electronics. One technology that has being receiving significant interest in recent years is resistive switching primarily due to its low dimensionality and nonvolatility. Here, we describe the development of resistive switching memory device arrays based on empty aluminum nanogap electrodes. By employing adhesion lithography, a low-temperature and large-area compatible nanogap fabrication technique, dense arrays of memory devices are demonstrated on both rigid and flexible plastic substrates. As-prepared devices exhibit nonvolatile memory operation with stable endurance, resistance ratios >10⁴ and retention times of several months. An intermittent analysis of the electrode microstructure reveals that controlled resistive switching is due to migration of metal from the electrodes into the nanogap under the application of an external electric field. This alternative form of resistive random access memory is promising for use in emerging sectors such as large-area electronics as well as in electronics for harsh environments, e.g., space, high/low temperature, magnetic influences, radiation, vibration, and pressure.

  13. Metal oxide nanostructures synthesized on flexible and solid substrates and used for catalysts, UV detectors, and chemical sensors

    Science.gov (United States)

    Willander, Magnus; Sadollahkhani, Azar; Echresh, Ahmad; Nur, Omer

    2014-03-01

    In this paper we demonstrate the visibility of the low temperature chemical synthesis for developing device quality material grown on flexible and solid substrates. Both colorimetric sensors and UV photodetectors will be presented. The colorimetric sensors developed on paper were demonstrated for heavy metal detection, in particular for detecting copper ions in aqueous solutions. The demonstrated colorimetric copper ion sensors developed here are based on ZnO@ZnS core-shell nanoparticles (CSNPs). These sensors demonstrated an excellent low detection limit of less than 1 ppm of copper ions. Further the colorimetric sensors operate efficiently in a wide pH range between 4 and 11, and even in turbulent water. The CSNPs were additionally used as efficient photocatalytic degradation element and were found to be more efficient than pure ZnO nanoparticles (NPs). Also p-NiO/n-ZnO thin film/nanorods pn junctions were synthesized by a two-step synthesis process and were found to act as efficient UV photodetectors. Additionally we show the effect of the morphology of different CuO nanostructures on the efficiency of photo catalytic degradation of Congo red organic dye.

  14. Liberation of metal clads of waste printed circuit boards by removal of halogenated epoxy resin substrate using dimethylacetamide.

    Science.gov (United States)

    Verma, Himanshu Ranjan; Singh, Kamalesh K; Mankhand, Tilak Raj

    2017-02-01

    Present work reports the evaluation of dimethylacetamide (DMAc) as a solvent to dissolve the halogenated epoxy resin substrate (HERS) of waste printed circuit boards (WPCBs). Studies revealed that HERS dissolution attributes to the cracking and delamination of WPCB's layers. Variation of the parameters governing the dissolution elucidated that dissolution is directly dependent on temperature and WPCBs concentration in DMAc. The results also showed that increase in the WPCBs size drastically retards the rate of HERS dissolution. After delamination, the spent DMAc was regenerated, and the dissolved HERS was recovered as residue. The chemical structure of regenerated solution and recovered residue were found to be similar to pure DMAc and untreated HERS, respectively. Cyclic usage of regenerated DMAc revealed that 3-5% of DMAc is lost after each usage cycle while its effectiveness to dissolve the HERS remains equivalent to the pure DMAc. The dissolution of HERS ensures the liberation of copper cladded on the surface of WPCBs, and thus the proposed process avoids the requirement of highly energy intensive metal liberation processes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. X-ray Crystallographic Studies of Substrate Binding to Aristolochene Synthase Suggest a Metal Ion Binding Sequence for Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Shishova,E.; Yu, F.; Miller, D.; Faraldos, J.; Zhao, Y.; Coates, R.; Allemann, R.; Cane, D.; Christianson, D.

    2008-01-01

    The universal sesquiterpene precursor, farnesyl diphosphate (FPP), is cyclized in an Mg2+-dependent reaction catalyzed by the tetrameric aristolochene synthase from Aspergillus terreus to form the bicyclic hydrocarbon aristolochene and a pyrophosphate anion (PPi) coproduct. The 2.1- Angstroms resolution crystal structure determined from crystals soaked with FPP reveals the binding of intact FPP to monomers A-C, and the binding of PPi and Mg2+B to monomer D. The 1.89- Angstroms resolution structure of the complex with 2-fluorofarnesyl diphosphate (2F-FPP) reveals 2F-FPP binding to all subunits of the tetramer, with Mg2+Baccompanying the binding of this analogue only in monomer D. All monomers adopt open activesite conformations in these complexes, but slight structural changes in monomers C and D of each complex reflect the very initial stages of a conformational transition to the closed state. Finally, the 2.4- Angstroms resolution structure of the complex with 12,13-difluorofarnesyl diphosphate (DF-FPP) reveals the binding of intact DF-FPP to monomers A-C in the open conformation and the binding of PPi, Mg2+B, and Mg2+C to monomer D in a predominantly closed conformation. Taken together, these structures provide 12 independent 'snapshots' of substrate or product complexes that suggest a possible sequence for metal ion binding and conformational changes required for catalysis.

  16. X-ray crystallographic studies of substrate binding to aristolochene synthase suggest a metal ion binding sequence for catalysis.

    Science.gov (United States)

    Shishova, Ekaterina Y; Yu, Fanglei; Miller, David J; Faraldos, Juan A; Zhao, Yuxin; Coates, Robert M; Allemann, Rudolf K; Cane, David E; Christianson, David W

    2008-05-30

    The universal sesquiterpene precursor, farnesyl diphosphate (FPP), is cyclized in an Mg(2+)-dependent reaction catalyzed by the tetrameric aristolochene synthase from Aspergillus terreus to form the bicyclic hydrocarbon aristolochene and a pyrophosphate anion (PP(i)) coproduct. The 2.1-A resolution crystal structure determined from crystals soaked with FPP reveals the binding of intact FPP to monomers A-C, and the binding of PP(i) and Mg(2+)(B) to monomer D. The 1.89-A resolution structure of the complex with 2-fluorofarnesyl diphosphate (2F-FPP) reveals 2F-FPP binding to all subunits of the tetramer, with Mg(2+)(B)accompanying the binding of this analogue only in monomer D. All monomers adopt open activesite conformations in these complexes, but slight structural changes in monomers C and D of each complex reflect the very initial stages of a conformational transition to the closed state. Finally, the 2.4-A resolution structure of the complex with 12,13-difluorofarnesyl diphosphate (DF-FPP) reveals the binding of intact DF-FPP to monomers A-C in the open conformation and the binding of PP(i), Mg(2+)(B), and Mg(2+)(C) to monomer D in a predominantly closed conformation. Taken together, these structures provide 12 independent "snapshots" of substrate or product complexes that suggest a possible sequence for metal ion binding and conformational changes required for catalysis.

  17. The growth of high density network of MOF nano-crystals across macroporous metal substrates - Solvothermal synthesis versus rapid thermal deposition

    Science.gov (United States)

    Maina, James W.; Gonzalo, Cristina Pozo; Merenda, Andrea; Kong, Lingxue; Schütz, Jürg A.; Dumée, Ludovic F.

    2018-01-01

    Fabrication of metal organic framework (MOF) films and membranes across macro-porous metal substrates is extremely challenging, due to the large pore sizes across the substrates, poor wettability, and the lack of sufficient reactive functional groups on the surface, which prevent high density nucleation of MOF crystals. Herein, macroporous stainless steel substrates (pore size 44 × 40 μm) are functionalized with amine functional groups, and the growth of ZIF-8 crystals investigated through both solvothermal synthesis and rapid thermal deposition (RTD), to assess the role of synthesis routes in the resultant membranes microstructure, and subsequently their performance. Although a high density of well interconnected MOF crystals was observed across the modified substrates following both techniques, RTD was found to be a much more efficient route, yielding high quality membranes under 1 h, as opposed to the 24 h required for solvothermal synthesis. The RTD membranes also exhibited high gas permeance, with He permeance of up to 2.954 ± 0.119 × 10-6 mol m-2 s-1 Pa-1, and Knudsen selectivities for He/N2, Ar/N2 and CO2/N2, suggesting the membranes were almost defect free. This work opens up route for efficient fabrication of MOF films and membranes across macro-porous metal supports, with potential application in electrically mediated separation applications.

  18. Growth of YBCO films on MgO-based rolling-assisted biaxially textured substrates templates

    Energy Technology Data Exchange (ETDEWEB)

    Paranthaman, M Parans; Aytug, T; Zhai, H Y; Heatherly, L; Goyal, A; Christen, D K [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2005-03-01

    We have developed a simple alternative buffer layer architecture for the rolling-assisted biaxially textured substrates (RABiTS) approach. Buffer layers with both oxygen and metal diffusion barrier properties are of interest. Cube textured magnesium oxide MgO buffers were grown directly on biaxially textured Ni and Ni-W3 at.% substrates using electron beam evaporation. We have also grown epitaxial MgO layers on 2 m long textured Ni-W3 at.% tapes in a reel-to-reel e-beam evaporation. Highly textured LaMnO{sub 3} (LMO) buffers were grown on MgO-buffered Ni substrates using rf sputtering. MgO and LMO buffers have been proved to be good oxygen diffusion barriers and Ni diffusion barriers, respectively. YBCO films with a J{sub c} of 1 x 10{sup 6} A cm{sup -2} at 77 K and self-field were grown on this newly developed architecture of LMO/MgO/Ni using pulsed laser deposition.

  19. Epitaxial growth of YBa2Cu3O7−x films on Ce0.9La0.1O2−y buffered yttria-stabilized zirconia substrates by an all-chemical-solution route

    DEFF Research Database (Denmark)

    Yue, Zhao; Wu, Wei; Tang, Xiao

    2014-01-01

    In view of high rate fabrication of coated conductors at low-cost, YBa2Cu3O7 (YBCO) films on Ce0.9La0.1O2−y buffered yttria-stabilized zirconia substrates were deposited by means of a novel low-fluorine metal–organic solution route. A high critical current density of 3 MA cm−2 (77 K, self field) ......) was achieved on such an all-chemical derived configuration. Structural characterization showed that the enhanced superconductivity performance of the YBCO films is mainly related to the defects induced by the interface....

  20. Dependence of the heavy-metal uptake of higher fungi on substrate composition and site factors. Abhaengigkeit der Schwermetallaufnahme hoeherer Pilze von der Substratzusammensetzung und von Standortsfaktoren

    Energy Technology Data Exchange (ETDEWEB)

    Dietl, G.

    1987-01-01

    The first part of the work investigates the effect of Cd (in the form of the nitrate) on self-cultured champignons (Agaricus bisporus) as regards mycelium growth and fruit development as well as influences on the toxic effect from various substrate additives. The experiments show A. bisporus to be a suitable species for producing standard materials for different heavy-metal concentrations and combinations. In the second part, the heavy-metal content in four different species, Mycena pura s.str., M. rosea, M. pelianthina and M. diosma from different sites (needle and leaf-wood) is established. According to the conclusion drawn, these mushrooms, because of their heavy-metal-accumulating properties, are definitely suited as biological indicators of heavy metal in soil. (MG) With 14 figs., 37 tabs.

  1. Development of Solution Buffer Layers for RABiTS Based YBCO Coated Conductors

    Energy Technology Data Exchange (ETDEWEB)

    Paranthaman, Mariappan Parans [ORNL; Qiu, Xiaofeng [ORNL; List III, Frederick Alyious [ORNL; Zhang, Yifei [ORNL; Li, Xiaoping [American Superconductor Corporation, Westborough, MA; Sathyamurthy, Srivatsan [ORNL; Thieme, C. L. H. [American Superconductor Corporation, Westborough, MA; Rupich, M. W. [American Superconductor Corporation, Westborough, MA

    2011-01-01

    Abstract The main objective of this research is to find a suitable alternate solution based seed layer for the standard RABiTS three-layer architecture of physical vapor deposited CeO cap/YSZ barrier/Y O seed on Ni-5%W metal tape. In the present work, we have identified CeO buffer layer as a potential replacement for Y O seeds. Using a metal-organic deposition (MOD) process, we have grown smooth, crack-free, epitaxial thin films of CeO (pure and Zr, Cu and Gd-doped) directly on biaxially textured Ni-5W substrates in short lengths. Detailed XRD studies indicate that a single epitaxial CeO phase with slightly improved out-of-plane texture compared to the texture of the underlying Ni-W substrates can be achieved in pure, undoped CeO samples. We have also demonstrated the growth of YSZ barrier layers on pure CeO seeds using sputtering. Both sputtered CeO cap layers and MOD-YBCO films were grown epitaxially on these YSZ-buffered MOD-CeO /Ni-5W substrates. High critical currents per unit width, of 264 A/cm (critical current density, of 3.3 MA/cm ) at 77 K and 0.01 T was achieved for 0.8 m thick MOD-YBCO films grown on MOD-CeO seeds. These results indicate that CeO films can be grown directly on Ni-5W substrates and still support high performance YBCO coated conductors. This work holds promise for a route for producing low-cost buffer architecture for RABiTS based YBCO coated conductors.

  2. Development of Solution Buffer Layers for RABiTS Based YBCO Coated Conductors

    Energy Technology Data Exchange (ETDEWEB)

    Paranthaman, Mariappan Parans [ORNL; Qiu, Xiaofeng [ORNL; Kim, Kyunghoon [ORNL; Shi, D. [University of Cincinnati; Zhang, Yifei [ORNL; Li, Xiaoping [American Superconductor Corporation, Westborough, MA; Sathyamurthy, Srivatsan [ORNL; Thieme, C. L. H. [American Superconductor Corporation, Westborough, MA; Rupich, M. W. [American Superconductor Corporation, Westborough, MA

    2010-01-01

    The main objective of this research is to find a suitable alternate solution based seed layer for the standard RABiTS three-layer architecture of physical vapor deposited CeO2 cap/YSZ barrier/Y2O3 seed on Ni-5%W metal tape. In the present work, we have identified CeO2 buffer layer as a potential replacement for Y2O3 seeds. Using a metal-organic deposition (MOD) process, we have grown smooth, crack-free, epitaxial thin films of CeO2 (both pure and Zr, Cu and Gd-doped) directly on biaxially textured Ni-5W substrates in short lengths. Detailed XRD studies indicate that a single epitaxial CeO2 phase with slightly improved out-of-plane texture compared to the texture of underlying Ni-W substrates can be achieved in pure, undoped CeO2 samples. We have also demonstrated the growth of YSZ barrier layers on pure CeO2 seeds using sputtering. Both sputtered CeO2 cap layers and MOD-YBCO films were grown epitaxially on these YSZ-buffered MOD-CeO2/Ni-5W substrates. High critical currents per unit width, Ic of 264 A/cm (critical current density, Jc of 3.3 MA/cm2) at 77 K and 0.01 T was achieved for 0.8 m thick MOD-YBCO films grown on MOD-CeO2 seeds. These results indicate that CeO2 films can be grown directly on Ni-5W substrates and still support high performance YBCO coated conductors. This work holds promise for a route for producing low-cost buffer architecture for RABiTS based YBCO coated conductors.

  3. Characterization of AlInN/AlN/GaN Heterostructures with Different AlN Buffer Thickness

    Science.gov (United States)

    Çörekçi, S.; Dugan, S.; Öztürk, M. K.; Çetin, S. Ş.; Çakmak, M.; Özçelik, S.; Özbay, E.

    2016-07-01

    Two AlInN/AlN/GaN heterostructures with 280-nm- and 400-nm-thick AlN buffer grown on sapphire substrates by metal-organic chemical vapor deposition (MOCVD) have been investigated by x-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL) and Hall-effect measurements. The symmetric (0002) plane with respect to the asymmetric (10bar{1}2) plane in the 280-nm-thick AlN buffer has a higher crystal quality, as opposed to the 400-nm-thick buffer. The thinner buffer improves the crystallinity of both (0002) and (10bar{1}2) planes in the GaN layers, it also provides a sizeable reduction in dislocation density of GaN. Furthermore, the lower buffer thickness leads to a good quality surface with an rms roughness of 0.30 nm and a dark spot density of 4.0 × 108 cm-2. The optical and transport properties of the AlInN/AlN/GaN structure with the relatively thin buffer are compatible with the enhancement in its structural quality, as verified by XRD and AFM results.

  4. Ultra-low voltage resistive switching of HfO2 buffered (001) epitaxial NiO films deposited on metal seed layers

    Science.gov (United States)

    Qiu, X. Y.; Wang, R. X.; Zhang, Z.; Wei, M. L.; Ji, H.; Chai, Y.; Zhou, F. C.; Dai, J. Y.; Zhang, T.; Li, L. T.; Meng, X. S.

    2017-10-01

    A set of (001) epitaxial NiO films were prepared on highly textured (001) Pt seed layers using magnetron sputtering, and their resistive switching performance was measured. Cube-to-cube epitaxial relationships of NiO(001)//Pt(001) and NiO[001]//Pt[001] were demonstrated. Current-voltage measurements revealed that the Ag/(001)NiO/(001)Pt capacitor structures exhibited stable bipolar switching behavior with an ON/OFF ratio of 20 and an endurance of over 5 × 103 cycles. Furthermore, inserting a HfO2 buffer layer between the NiO film and the Ag top electrode increased the ON/OFF ratio to more than 103 and reduced the SET/RESET voltage to below ±0.2 V. These enhancements are attributed to the differing filament growth mechanisms that occur in the NiO and HfO2 layers. The present work suggests that Ag/HfO2/(001)NiO/(001)Pt capacitor structures are a promising technology for next-generation, ultra-low voltage resistive switching memory.

  5. A parallel buffer tree

    DEFF Research Database (Denmark)

    Sitchinava, Nodar; Zeh, Norbert

    2012-01-01

    We present the parallel buffer tree, a parallel external memory (PEM) data structure for batched search problems. This data structure is a non-trivial extension of Arge's sequential buffer tree to a private-cache multiprocessor environment and reduces the number of I/O operations by the number...... of available processor cores compared to its sequential counterpart, thereby taking full advantage of multicore parallelism. The parallel buffer tree is a search tree data structure that supports the batched parallel processing of a sequence of N insertions, deletions, membership queries, and range queries...

  6. Secondary metabolites and metal content dynamics in Teucrium montanum L. and Teucrium chamaedrys L. from habitats with serpentine and calcareous substrate.

    Science.gov (United States)

    Zlatić, Nenad M; Stanković, Milan S; Simić, Zoran S

    2017-03-01

    The purpose of this comparative analysis is the determination of the total quantity of metals (Mg, Ca, K, Ni, Fe, Mn, Zn, Cu, Cr and Pb) in soil samples, above ground plant parts and tea made of plants Teucrium montanum and T. chamaedrys from different serpentine and calcareous habitats as well as of the total quantity of phenolic compounds and antioxidant activity. The obtained results showed that the quantities of certain metals (Mg, Fe, Ni and Mn) in the soil from the serpentine habitats were greater in comparison with other metals (Ca, Zn and Pb) which were more frequently found in the soil from the calcareous habitats. The results demonstrated that the analysed plant samples from the serpentine habitats contained higher quantity of Fe, Ni and Cr as opposed to the plant samples from the calcareous habitats which contained greater quantity of Ca and Zn. Although the studied species accumulate analysed metals in different quantities, depending on the substrate type, they are not hyperaccumulators of these metals. The use of these species from serpentine habitats for tea preparation is safe to a great extent, because in spite of the determined metal absorption by plant organs, the tea does not contain dangerous quantity of heavy metals. The results showed greater total quantity of phenolic compounds and the higher level of antioxidant activity in the plant samples from serpentine habitats in comparison with the samples from calcareous habitats, which is an indicator of one of the mechanisms of adaptation to the serpentine habitat conditions.

  7. Initial-rate kinetics of human NMN-adenylyltransferases: substrate and metal ion specificity, inhibition by products and multisubstrate analogues, and isozyme contributions to NAD+ biosynthesis.

    Science.gov (United States)

    Sorci, Leonardo; Cimadamore, Flavio; Scotti, Stefania; Petrelli, Riccardo; Cappellacci, Loredana; Franchetti, Palmarisa; Orsomando, Giuseppe; Magni, Giulio

    2007-04-24

    Initial-rate and product inhibition studies revealed distinctive ordered ternary complex kinetic mechanisms, substrate specificities, and metal ion preferences for the three isozymes of human nicotinamide mononucleotide adenylyl-transferase (NMNAT, EC 2.7.7.1). ATP binds before NMN with nuclear isozyme NMNAT1 and Golgi apparatus NMNAT2, but the opposite order is observed with the mitochondrial isozyme NMNAT3. Only the latter utilizes ITP efficiently in place of ATP, and while NMNH conversion to NADH by NMNAT1 and NMNAT3 occurs at similar rates, conversion by NMNAT2 is much slower. These isozymes can also be discriminated by their action on tiazofurin monophosphate (TrMP), a metabolite of the antineoplastic prodrug tiazofurin. Our finding that TrMP is only a substrate with NMNAT1 and NMNAT3 reveals for the first time an organelle selectivity in the metabolism of this important drug. In search of additional ways to discriminate these isozymes, we synthesized and tested the P1-(nicotinamide/nicotinate-riboside-5')-Pn-(adenosine-5') dinucleotides Np3AD, Np4AD, and Nap4AD. In addition to being highly effective inhibitors, these multisubstrate geometric inhibitors gave inhibition patterns that are consistent with the aforementioned isozyme differences in substrate binding order. Distinctive differences in their substrate specificity and metal ion selectivity also permitted us to quantify individual isozyme contributions to NAD+ formation in human cell extracts.

  8. Integrated pinning centers in YBa{sub 2}Cu{sub 3}O{sub x} thick films on single-crystalline and textured metal substrates

    Energy Technology Data Exchange (ETDEWEB)

    Mikheenko, P; Dang, V-S; Sarkar, A; Abell, J S; Crisan, A, E-mail: p.mikheenko@bham.ac.uk [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2011-03-01

    The second-generation coated tapes of high temperature superconductors (HTS) deposited on textured metal substrates strongly rely on the introduction of extended nano-defects in order to enhance their critical current. A proven effective way to introduce such defects is growing BaZrO{sub 3} (BZO) nano-rods and an alternative way is to generate HTS columnar growth using nanoparticles of noble metals. Here we report the combination of these methods. It allows achieving controlled pinning and high critical current in YBa{sub 2}Cu{sub 3}O{sub x} films deposited on single crystal substrates and significantly improves critical current in coated conductors deposited on rolling-assisted biaxially-textured metal substrates (RABiTS). The superconducting properties of thick (up to 5 micron) conductors are analysed using DC-magnetisation, AC-susceptibility and angle-dependent transport measurements. TEM imaging is used to confirm the presence of extended defects in the tapes.

  9. A Triazole-Containing Metal-Organic Framework as a Highly Effective and Substrate Size-Dependent Catalyst for CO2 Conversion.

    Science.gov (United States)

    Li, Pei-Zhou; Wang, Xiao-Jun; Liu, Jia; Lim, Jie Sheng; Zou, Ruqiang; Zhao, Yanli

    2016-02-24

    A highly porous metal-organic framework (MOF) incorporating both exposed metal sites and nitrogen-rich triazole groups was successfully constructed via solvothermal assembly of a clicked octcarboxylate ligand and Cu(II) ions, which presents a high affinity toward CO2 molecules clearly verified by gas adsorption and Raman spectral detection. The constructed MOF featuring CO2-adsorbing property and exposed Lewis-acid metal sites could serve as an excellent catalyst for CO2-based chemical fixation. Catalytic activity of the MOF was confirmed by remarkably high efficiency on CO2 cycloaddition with small epoxides. When extending the substrates to larger ones, its activity showed a sharp decrease. These observations reveal that MOF-catalyzed CO2 cycloaddition of small substrates was carried out within the framework, while large ones cannot easily enter into the porous framework for catalytic reactions. Thus, the synthesized MOF exhibits high catalytic selectivity to different substrates on account of the confinement of the pore diameter. The high efficiency and size-dependent selectivity toward small epoxides on catalytic CO2 cycloaddition make this MOF a promising heterogeneous catalyst for carbon fixation.

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

    Energy Technology Data Exchange (ETDEWEB)

    Vasbinder, Michael John [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    fitting the observed rate constants to the 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.

  11. Effect of dual buffer layer structure on the epitaxial growth of AlN on sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, D.G., E-mail: dgzhao@red.semi.ac.cn [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Jiang, D.S.; Wu, L.L.; Le, L.C.; Li, L.; Chen, P.; Liu, Z.S. [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Zhu, J.J.; Wang, H.; Zhang, S.M. [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215125 (China); Yang, H. [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215125 (China)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer A dual AlN buffer layer structure is proposed to grow AlN films. Black-Right-Pointing-Pointer AlN films could be improved obviously by using the dual AlN buffer layer. Black-Right-Pointing-Pointer The physical mechanism are discussed. - Abstract: A dual AlN buffer layer structure, including an isolated layer and a nucleation layer, is proposed to improve the growth of AlN films on sapphire substrate by metal organic chemical vapor deposition. This method is aimed to weaken the negative nitridation effect and improve lateral growth condition in the initial growth stage. It is found that suitably increasing the thickness of the nucleation layer is in favor of a better structural quality of the AlN film. An examination of surface morphology by atomic force microscopy suggests that the thicker the dual AlN buffer layer, the rougher the surface, and a higher quality of AlN epilayer is resulted.

  12. Investigation into the role of sodium chloride deposited on oxide and metal substrates in the initiation of hot corrosion

    Science.gov (United States)

    Birks, N.

    1983-01-01

    Sodium chloride is deposited on the surface of alumina substrates and exposed to air containing 1% SO2 at temperatures between 500 C and 700 C. In all cases the sodium chloride was converted to sodium sulfate. The volatilization of sodium chloride from the original salt particles was responsible for the development of a uniform coating of sodium sulfate on the alumina substrate. At temperatures above 625 C, a liquid NaCl-Na2SO4 autectic was formed on the substrate. The mechanisms for these reactions are given. One of the main roles of NaCl in low temperature hot corrosion lies in enabling a corrosive liquid to form.

  13. Electrostatic interactions between ions near Thomas-Fermi substrates and the surface energy of ionic crystal at imperfect metals

    Science.gov (United States)

    Kaiser, V.; Comtet, J.; Niguès, A.; Siria, A.; Coasne, B.; Bocquet, L.

    2017-01-01

    The electrostatic interaction between two charged particles is strongly modified in the vicinity of a metal. This situation is usually accounted for by the celebrated image charges approach, which was further extended to account for the electronic screening properties of the metal at the level of the Thomas-Fermi description. In this paper we build upon the approach by [Kornyshev et al. Zh. Eksp. Teor. Fiz., 78(3):1008–1019, 1980] and successive works to calculate the 1-body and 2-body electrostatic energy of ions near a metal in terms of the Thomas-Fermi screening length. We propose workable approximations suitable for molecular simulations of ionic systems close to metallic walls. Furthermore, we use this framework to calculate analytically the electrostatic contribution to the surface energy of a one dimensional crystal at a metallic wall and its dependence on the Thomas-Fermi screening length. These calculations provide a simple interpretation for the surface energy in terms of image charges, which allow for an estimate of interfacial properties in more complex situations of a disordered ionic liquid close to a metal surface. A counterintuitive outcome is that electronic screening, as characterized by a molecular Thomas-Fermi length ℓTF, profoundly affects the wetting of ionic systems close to a metal, in line with the recent experimental observation of capillary freezing of ionic liquids in metallic confinement. PMID:28436506

  14. Electrostatic interactions between ions near Thomas-Fermi substrates and the surface energy of ionic crystals at imperfect metals.

    Science.gov (United States)

    Kaiser, V; Comtet, J; Niguès, A; Siria, A; Coasne, B; Bocquet, L

    2017-07-01

    The electrostatic interaction between two charged particles is strongly modified in the vicinity of a metal. This situation is usually accounted for by the celebrated image charges approach, which was further extended to account for the electronic screening properties of the metal at the level of the Thomas-Fermi description. In this paper we build upon a previous approach [M. A. Vorotyntsev and A. A. Kornyshev, Zh. Eksp. Teor. Fiz., 1980, 78(3), 1008-1019] and successive works to calculate the 1-body and 2-body electrostatic energy of ions near a metal in terms of the Thomas-Fermi screening length. We propose workable approximations suitable for molecular simulations of ionic systems close to metallic walls. Furthermore, we use this framework to calculate analytically the electrostatic contribution to the surface energy of a one dimensional crystal at a metallic wall and its dependence on the Thomas-Fermi screening length. These calculations provide a simple interpretation for the surface energy in terms of image charges, which allows for an estimation of the interfacial properties in more complex situations of a disordered ionic liquid close to a metal surface. The counter-intuitive outcome is that electronic screening, as characterized by a molecular Thomas-Fermi length lTF, profoundly affects the wetting of ionic systems close to a metal, in line with the recent experimental observation of capillary freezing of ionic liquids in metallic confinement.

  15. Buffer Zone Sign Template

    Science.gov (United States)

    The certified pesticide applicator is required to post a comparable sign, designating a buffer zone around the soil fumigant application block in order to control exposure risk. It must include the don't walk symbol, product name, and applicator contact.

  16. Methods for improved growth of group III nitride buffer layers

    Science.gov (United States)

    Melnik, Yurity; Chen, Lu; Kojiri, Hidehiro

    2014-07-15

    Methods are disclosed for growing high crystal quality group III-nitride epitaxial layers with advanced multiple buffer layer techniques. In an embodiment, a method includes forming group III-nitride buffer layers that contain aluminum on suitable substrate in a processing chamber of a hydride vapor phase epitaxy processing system. A hydrogen halide or halogen gas is flowing into the growth zone during deposition of buffer layers to suppress homogeneous particle formation. Some combinations of low temperature buffers that contain aluminum (e.g., AlN, AlGaN) and high temperature buffers that contain aluminum (e.g., AlN, AlGaN) may be used to improve crystal quality and morphology of subsequently grown group III-nitride epitaxial layers. The buffer may be deposited on the substrate, or on the surface of another buffer. The additional buffer layers may be added as interlayers in group III-nitride layers (e.g., GaN, AlGaN, AlN).

  17. Structural properties of Al-rich AlInN grown on c-plane GaN substrate by metal-organic chemical vapor deposition.

    Science.gov (United States)

    Lin, Pei-Yin; Chen, Jr-Yu; Shih, Yi-Sen; Chang, Li

    2014-01-01

    The attractive prospect for AlInN/GaN-based devices for high electron mobility transistors with advanced structure relies on high-quality AlInN epilayer. In this work, we demonstrate the growth of high-quality Al-rich AlInN films deposited on c-plane GaN substrate by metal-organic chemical vapor deposition. X-ray diffraction, scanning electron microscopy, and scanning transmission electron microscopy show that the films lattice-matched with GaN can have a very smooth surface with good crystallinity and uniform distribution of Al and In in AlInN.

  18. Frontier molecular orbitals of a single molecule adsorbed on thin insulating films supported by a metal substrate: electron and hole attachment energies

    Science.gov (United States)

    Scivetti, Iván; Persson, Mats

    2017-09-01

    We present calculations of vertical electron and hole attachment energies to the frontier orbitals of a pentacene molecule absorbed on multi-layer sodium chloride films supported by a copper substrate using a simplified density functional theory (DFT) method. The adsorbate and the film are treated fully within DFT, whereas the metal is treated implicitly by a perfect conductor model. We find that the computed energy gap between the highest and lowest unoccupied molecular orbitals—HOMO and LUMO -from the vertical attachment energies increases with the thickness of the insulating film, in agreement with experiments. This increase of the gap can be rationalised in a simple dielectric model with parameters determined from DFT calculations and is found to be dominated by the image interaction with the metal. We find, however, that this simplified model overestimates the downward shift of the energy gap in the limit of an infinitely thick film.

  19. Graphene Growth on Pre-patterned Copper Film with Nickel as a Buffer Layer

    Science.gov (United States)

    Li, Yang; Deng, Wu-Zhu; Wang, Dong-Zhao; Chen, Yang-Yang; Zhou, Wen-Li

    2015-11-01

    Selective graphene growth has been simultaneously achieved on oxidized silicon substrate with three kinds of pre-patterned rectangular metal films, i.e., Cu/Ni double layer, and Ni and Cu single layer film, by atmospheric chemical vapor deposition at 1020°C. The top graphene maintains the micron-scale patterning of the metal film underneath. It was found that single layer graphene growth is more favorable on the Cu/Ni double layer film than on either single layer. The morphology and structure study of the pre-patterned metal substrates before and after graphene growth indicated that Ni functions as a buffer layer to significantly weaken the lattice mismatch between the copper and silicon substrate, resulting in a smoother and larger grain-sized Cu surface. It is also suggested that Ni diffuses to the Cu surface and participates in the graphene growth during the chemical vapor deposition (CVD) process. Defect-free single layer graphene growth can be obtained when the ratio of Cu/Ni is appropriate with respect to their thickness and the feature size of rectangular patterning.

  20. Pilot-scale passive bioreactors for the treatment of acid mine drainage: efficiency of mushroom compost vs. mixed substrates for metal removal.

    Science.gov (United States)

    Song, Hocheol; Yim, Gil-Jae; Ji, Sang-Woo; Neculita, Carmen Mihaela; Hwang, Taewoon

    2012-11-30

    Pilot-scale field-testing of passive bioreactors was performed to evaluate the efficiency of a mixture of four substrates (cow manure compost, mushroom compost, sawdust, and rice straw) relative to mushroom compost alone, and of the effect of the Fe/Mn ratio, during the treatment of acid mine drainage (AMD) over a 174-day period. Three 141 L columns, filled with either mushroom compost or the four substrate mixture (in duplicate), were set-up and fed with AMD from a closed mine site, in South Korea, using a 4-day hydraulic retention time. In the former bioreactor, effluent deterioration was observed over 1-2 months, despite the good efficiency predicted by the physicochemical characterization of mushroom compost. Steady state effluent quality was then noted for around 100 days before worsening in AMD source water occurred in response to seasonal variations in precipitation. Such changes in AMD quality resulted in performance deterioration in all reactors followed by a slow recovery toward the end of testing. Both substrates (mushroom compost and mixtures) gave satisfactory performance in neutralizing pH (6.1-7.8). Moreover, the system was able to consistently reduce sulfate from day 49, after the initial leaching out from organic substrates. Metal removal efficiencies were on the order of Al (∼100%) > Fe (68-92%) > Mn (49-61%). Overall, the mixed substrates showed comparable performance to mushroom compost, while yielding better effluent quality upon start-up. The results also indicated mushroom compost could release significant amounts of Mn and sulfate during bioreactor operation. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. The effect of heavy metals on the total protein concentration of Typha latifolia plants, growing in a substrate containing sewage sludge compost and watered with metaliferus wastewater.

    Science.gov (United States)

    Manios, T; Stentiford, E I; Millner, P

    2002-09-01

    Typha latifolia plants, commonly known as cattails, were grown in a mixture of sewage sludge compost, commercial compost and perlite. Large 6.5 L pots were used with one well developed plant in each pot, divided in five groups. Four groups were irrigated with a solution containing different concentrations of Cd, Cu, Ni, Pb and Zn for a period of 10 weeks, where the fifth was used as a blank. Changes in the concentration of total protein in the leaves/stems were monitored aiming to study the effect of heavy metals from both the substrate and the wastewater on the plants' development and health. At the end of the experiment in the leaves/stems of Typha latifolia the mean concentration of Ni and Zn reached values of 27.50 and 60.83 mg/kg of d.w. respectively. Similar high concentrations were recorded for all five metals. This, however, did not resulted in an inhibition of the plants development and health in three of the four groups as evidenced by the increasing concentrations of the total protein in the leaves' tissue. Only in the fourth group, where the stronger solution was used, some evidence of inhibition occurred after the 8th week. The presence of NO- as part of the metals' salts (growth factor), the short period of the experiment and the natural tolerance of Typha latifolia in heavy metals toxicity could explain such phenomenon.

  2. Qualitative analysis of thin films of crude oil deposits on the metallic substrate by Fourier transform infrared (FTIR) microscopy

    DEFF Research Database (Denmark)

    Batina, N.; Reyna-Cordova, A.; Trinidad-Reyes, Y.

    2005-01-01

    Thin films of crude oil samples were prepared for atomic force microscopy (AFM) analysis on the gold substrate. Sample preparation involved evaporation during a long (24 h) but mild thermal exposure (80 °C). Fourier transform infrared (FTIR) microscopy (reflectance spectroscopy) was employed...

  3. [Influences of matter variations on pollution buffer capacity of landfill leachate polluted subsurface environment].

    Science.gov (United States)

    Dong, Jun; Zhao, Yong-sheng; Zhou, Rui; Hong, Mei; Zhang, Wei-hong; Zhu, Zhi-guo

    2009-12-01

    Columns filled with fine sand were constructed to investigate influences of subsurface environment and main constituent variations caused by landfill leachate pollution on pH buffer capacity and redox buffer capacity of sediments. Experimental results indicated that the subsurface environment had significant impacts on pH and redox buffer capacity. The pH buffer capacity increased 12.4%, 10.8%, 19.8% and 11.1% in MGZ/SRZ, IRZ, NRZ and ORZ compared with background value, respectively. pH buffer and redox buffer were interaction and inter-promotion, which influenced natural attenuation processes of pollutants in subsurface directly. Content of iron oxides, organic substrate, SOC2(2-) and NH4+ -N in sediments had different impacts on pH buffer and redox buffer capacity, and the overall pollution buffer capacity of system was comprehensive results of constituents.

  4. All-inkjet-printed flexible electronics fabrication on a polymer substrate by low-temperature high-resolution selective laser sintering of metal nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Seung H [Department of Mechanical Engineering, University of California, 6177 Etcheverry Hall, Berkeley, CA 94720-1740 (United States); Pan Heng [Department of Mechanical Engineering, University of California, 6177 Etcheverry Hall, Berkeley, CA 94720-1740 (United States); Grigoropoulos, Costas P [Department of Mechanical Engineering, University of California, 6177 Etcheverry Hall, Berkeley, CA 94720-1740 (United States); Luscombe, Christine K [Department of Chemistry, University of California, Berkeley, CA 94720-1460 (United States); Frechet, Jean M J [Department of Chemistry, University of California, Berkeley, CA 94720-1460 (United States); Poulikakos, Dimos [Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, CH-8092 Zurich (Switzerland)

    2007-08-29

    All-printed electronics is the key technology to ultra-low-cost, large-area electronics. As a critical step in this direction, we demonstrate that laser sintering of inkjet-printed metal nanoparticles enables low-temperature metal deposition as well as high-resolution patterning to overcome the resolution limitation of the current inkjet direct writing processes. To demonstrate this process combined with the implementation of air-stable carboxylate-functionalized polythiophenes, high-resolution organic transistors were fabricated in ambient pressure and room temperature without utilizing any photolithographic steps or requiring a vacuum deposition process. Local thermal control of the laser sintering process could minimize the heat-affected zone and the thermal damage to the substrate and further enhance the resolution of the process. This local nanoparticle deposition and energy coupling enable an environmentally friendly and cost-effective process as well as a low-temperature manufacturing sequence to realize large-area, flexible electronics on polymer substrates.

  5. Optimization of Grit-Blasting Process Parameters for Production of Dense Coatings on Open Pores Metallic Foam Substrates Using Statistical Methods

    Science.gov (United States)

    Salavati, S.; Coyle, T. W.; Mostaghimi, J.

    2015-10-01

    Open pore metallic foam core sandwich panels prepared by thermal spraying of a coating on the foam structures can be used as high-efficiency heat transfer devices due to their high surface area to volume ratio. The structural, mechanical, and physical properties of thermally sprayed skins play a significant role in the performance of the related devices. These properties are mainly controlled by the porosity content, oxide content, adhesion strength, and stiffness of the deposited coating. In this study, the effects of grit-blasting process parameters on the characteristics of the temporary surface created on the metallic foam substrate and on the twin-wire arc-sprayed alloy 625 coating subsequently deposited on the foam were investigated through response surface methodology. Characterization of the prepared surface and sprayed coating was conducted by scanning electron microscopy, roughness measurements, and adhesion testing. Using statistical design of experiments, response surface method, a model was developed to predict the effect of grit-blasting parameters on the surface roughness of the prepared foam and also the porosity content of the sprayed coating. The coating porosity and adhesion strength were found to be determined by the substrate surface roughness, which could be controlled by grit-blasting parameters. Optimization of the grit-blasting parameters was conducted using the fitted model to minimize the porosity content of the coating while maintaining a high adhesion strength.

  6. MOD Buffer/YBCO Approach to Fabricate Low-Cost Second Generation HTS Wires

    Energy Technology Data Exchange (ETDEWEB)

    Paranthaman, Mariappan Parans [ORNL; Sathyamurthy, Srivatsan [ORNL; Bhuiyan, Md S [ORNL; Martin, Patrick M [ORNL; Aytug, Tolga [ORNL; Kim, Kyunghoon [ORNL; Fayek, Mostafa [ORNL; Leonard, Keith J [ORNL; Li, Jing [ORNL; Zhang, W. [American Superconductor Corporation, Westborough, MA; Rupich, Marty [American Superconductor Corporation, Westborough, MA

    2007-01-01

    The metal organic deposition (MOD) of buffer layers on RABiTS substrates is considered a potential, low-cost approach to manufacturing high performance Second Generation (2G) high temperature superconducting (HTS) wires. The typical architecture used by American Superconductor in their 2G HTS wire consists of a Ni-W (5 at.%) substrate with a reactively sputtered Y2O3 seed layer, YSZ barrier layer and a CeO2 cap layer. This architecture supports critical currents of over 300 A/cm-width (77 K, self-field) with 0.8 mum YBCO films deposited by the TFA-MOD process. The main challenge in the development of the MOD buffers is to match or exceed the performance of the standard vacuum deposited buffer architecture. We have recently shown that the texture and properties of MOD - La2Zr2Ogamma (LZO) barrier layers can be improved by inserting a thin sputtered Y2O3 seed layer and prepared MOD deposited LZO layers followed by MOD or RF sputtered CeO2 cap layers that support MOD-YBCO films with Ic's of 200 and 255 A/cm-width, respectively. Detailed X-ray and microstructural characterizations indicated that MOD - CeO2 cap reacted completely with MOD YBCO to form BaCeOs. However, sputtered CeO2 cap/MOD YBCO interface remains clean. By further optimizing the coating conditions and reducing the heat-treatment temperatures, we have demonstrated an Ic of 336 A/cm with improved LZO layers and sputtered CeO2 cap and exceeded the performance of that of standard vacuum deposited buffers.

  7. Metal Decoration Effects on the Gas-Sensing Properties of 2D Hybrid-Structures on Flexible Substrates

    Directory of Open Access Journals (Sweden)

    Byungjin Cho

    2015-09-01

    Full Text Available We have investigated the effects of metal decoration on the gas-sensing properties of a device with two-dimensional (2D molybdenum disulfide (MoS2 flake channels and graphene electrodes. The 2D hybrid-structure device sensitively detected NO2 gas molecules (>1.2 ppm as well as NH3 (>10 ppm. Metal nanoparticles (NPs could tune the electronic properties of the 2D graphene/MoS2 device, increasing sensitivity to a specific gas molecule. For instance, palladium NPs accumulate hole carriers of graphene/MoS2, electronically sensitizing NH3 gas molecules. Contrarily, aluminum NPs deplete hole carriers, enhancing NO2 sensitivity. The synergistic combination of metal NPs and 2D hybrid layers could be also applied to a flexible gas sensor. There was no serious degradation in the sensing performance of metal-decorated MoS2 flexible devices before/after 5000 bending cycles. Thus, highly sensitive and endurable gas sensor could be achieved through the metal-decorated 2D hybrid-structure, offering a useful route to wearable electronic sensing platforms.

  8. Structural and microstructural characterization of III-nitrides on 6H-silicon carbide (0001) substrates

    Science.gov (United States)

    Preble, Edward Alfred

    Characterization of nitride films on 6H-SiC (0001) wafers via x-ray, TEM, and AFM was accomplished on standard GAN thin films with AlN or AlGaN buffer layers. TEM sample thinning capability was improved through the use of Nomarski in an optical microscope to gauge the thickness of the sample during preparation. TEM analysis was then completed of Au and Pt films deposited on chemical vapor cleaned GaN with annealed up to 800°C. Chemical reactions were detected in x-ray measurements of the 800°C Pt samples and GaN/metal interface roughening were confirmed by TEM images in both metals. Interface roughening is attributed to the chemical reactions and interfacial stresses greater than the yield stress of the metal created during heat treatments by the difference in the thermal expansion coefficients of the Ga and the metals. The GaN rocking curves were found to track very closely to the values of the underlying substrate and changes in buffer layer growth temperatures were found to change the screw and edge dislocation populations of subsequent GaN layers. GaN grown on 1030°C AlN buffer layers showed the lowest edge dislocation populations when compared against buffers grown in the range of 1010--1220°C, even though the 1220°C AlN was much smoother. AlGaN buffer layers provided more edge dislocation reduction, with a 1090°C Al0.2Ga0.8N layer yielding the best GaN rocking curve values found in this work. GaN films with AlN buffer layers grown on hydrogen etched SiC substrates did not show rocking curve improvement when compared against samples with unetched substrates. The AlN layers showed extremely narrow, substrate limited, on-axis rocking curve values, but it is not clear as to whether additional defects are present that may broaden the off-axis rocking curves, causing the poorer results seen in the GaN films. Reciprocal space maps of uncoalesced, maskless pendeo epitaxy samples revealed that the wing regions are shielded from poor substrate material when

  9. Substrate effects on the structure and optical properties of epitaxial PbTiO{sub 3} thin films prepared by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Foster, C.M.; Li, Z.; Bai, G.R.; You, H.; Guo, D.; Chang, H.L.M.

    1994-04-01

    Epitaxial PbTiO{sub 3} films were prepared by metal-organic chemical vapor deposition (MOCVD) on MgO(001), SrTiO{sub 3}(001) and LaAlO{sub 3}(001) surfaces. Four-circle X-ray diffraction and optical waveguiding experiments were performed to characterize the deposited films. The films on all three substrates were single-crystal; however, the domain structure of the films was strongly dependent on the substrate material. Films on MgO and LaAIO{sub 3} substrates showed a large amount of 90{degrees} domain structures, whereas, the degree of twinning was greatly suppressed for films on SrTiO{sub 3}. The refractive indices and optical birefringence of the films were measured as a function of wavelength using the film-prism coupling method. The authors found that for films on LaAIO{sub 3}(001), the ordinary index and for films on MgO(001) both the ordinary and extraordinary refractive indices were higher than those of bulk single-crystal PbTiO{sub 3}. For films grown on SrTiO{sub 3}(001), the ordinary refractive index was very close to that of single crystal PbTiO{sub 3}. They correlate the increased refractive index and the reduced birefringence to the degree of epitaxial strain and twinning in the samples, respectively.

  10. Creep in buffer clay

    Energy Technology Data Exchange (ETDEWEB)

    Pusch, R. [Geodevelopment AB, Lund (Sweden); Adey, R. [Computational Mechanics BEASY, Southampton (United Kingdom)

    1999-12-01

    The study involved characterization of the microstructural arrangement and molecular forcefields in the buffer clay for getting a basis for selecting suitable creep models. It is concluded that the number of particles and wide range of the particle bond spectrum require that stochastical mechanics and thermodynamics will be considered and they are basic to the creep model proposed for predicting creep settlement of the canisters. The influence of the stress level on creep strain of MX-80 clay is not well known but for the buffer creep is approximately proportional to stress. Theoretical considerations suggest a moderate impact for temperatures up to 90 deg C and this is supported by model experiments. It is believed that the assumption of strain being proportional to temperature is conservative. The general performance of the stochastic model can be illustrated in principle by use of visco-elastic rheological models implying a time-related increase in viscosity. The shear-induced creep settlement under constant volume conditions calculated by using the proposed creep model is on the order of 1 mm in ten thousand years and up to a couple of millimeters in one million years. It is much smaller than the consolidation settlement, which is believed to be on the order of 10 mm. The general conclusion is that creep settlement of the canisters is very small and of no significance to the integrity of the buffer itself or of the canisters.

  11. Zn-bis-glutathionate is the best co-substrate of the monomeric phytochelatin synthase from the photosynthetic heavy metal-hyperaccumulator Euglena gracilis.

    Science.gov (United States)

    García-García, Jorge D; Girard, Lourdes; Hernández, Georgina; Saavedra, Emma; Pardo, Juan P; Rodríguez-Zavala, José S; Encalada, Rusely; Reyes-Prieto, Adrián; Mendoza-Cózatl, David G; Moreno-Sánchez, Rafael

    2014-03-01

    The phytochelatin synthase from photosynthetic Euglena gracilis (EgPCS) was analyzed at the transcriptional, kinetic, functional, and phylogenetic levels. Recombinant EgPCS was a monomeric enzyme able to synthesize, in the presence of Zn(2+) or Cd(2+), phytochelatin2-phytochelatin4 (PC2-PC4) using GSH or S-methyl-GS (S-methyl-glutathione), but not γ-glutamylcysteine or PC2 as a substrate. Kinetic analysis of EgPCS firmly established a two-substrate reaction mechanism for PC2 synthesis with Km values of 14-22 mM for GSH and 1.6-2.5 μM for metal-bis-glutathionate (Me-GS2). EgPCS showed the highest Vmax and catalytic efficiency with Zn-(GS)2, and was inactivated by peroxides. The EgPCS N-terminal domain showed high similarity to that of other PCSases, in which the typical catalytic core (Cys-70, His-179 and Asp-197) was identified. In contrast, the C-terminal domain showed no similarity to other PCSases. An EgPCS mutant comprising only the N-terminal 235 amino acid residues was inactive, suggesting that the C-terminal domain is essential for activity/stability. EgPCS transcription in Euglena cells was not modified by Cd(2+), whereas its heterologous expression in ycf-1 yeast cells provided resistance to Cd(2+) stress. Phylogenetic analysis of the N-terminal domain showed that EgPCS is distant from plants and other photosynthetic organisms, suggesting that it evolved independently. Although EgPCS showed typical features of PCSases (constitutive expression; conserved N-terminal domain; kinetic mechanism), it also exhibited distinct characteristics such as preference for Zn-(GS)2 over Cd-(GS)2 as a co-substrate, a monomeric structure, and ability to solely synthesize short-chain PCs, which may be involved in conferring enhanced heavy-metal resistance.

  12. Understanding inherent substrate selectivity during atomic layer deposition: Effect of surface preparation, hydroxyl density, and metal oxide composition on nucleation mechanisms during tungsten ALD

    Science.gov (United States)

    Lemaire, Paul C.; King, Mariah; Parsons, Gregory N.

    2017-02-01

    Area-selective thin film deposition is expected to be important for advanced sub-10 nanometer semiconductor devices, enabling feature patterning, alignment to underlying structures, and edge definition. Several atomic layer deposition (ALD) processes show inherent propensity for substrate-dependent nucleation. This includes tungsten ALD (W-ALD) which is more energetically favorable on Si than on SiO2. However, the selectivity is often lost after several ALD cycles. We investigated the causes of tungsten nucleation on SiO2 and other "non-growth" surfaces during the WF6/SiH4 W-ALD process to determine how to expand the "selectivity window." We propose that hydroxyls, generated during the piranha clean, act as nucleation sites for non-selective deposition and show that by excluding the piranha clean or heating the samples, following the piranha clean, extends the tungsten selectivity window. We also assessed how the W-ALD precursors interact with different oxide substrates though individual WF6 and SiH4 pre-exposures prior to W-ALD deposition. We conclude that repeated SiH4 pre-exposures reduce the tungsten nucleation delay, which is attributed to SiH4 adsorption on hydroxyl sites. In addition, oxide surfaces were repeatedly exposed to WF6, which appears to form metal fluoride species. We attribute the different tungsten nucleation delay on Al2O3 and TiO2 to the formation of nonvolatile and volatile metal fluoride species, respectively. Through this study, we have increased the understanding of ALD nucleation and substrate selectivity, which are pivotal to improving the selectivity window for W-ALD and other ALD processes.

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

    Science.gov (United States)

    Birks, N.

    1981-01-01

    Morphological aspects of the conversion to Na2SO4 of NaCl deposits over the temperature range 500-700 C, in air with added SO2 and H2O. Progress of the reaction was observed by withdrawing samples at various times and examining them under the scanning electron microscope using EDAX to assess the extent of chloride to sulfate conversion. These initial results show that the conversion to Na2SO4 proceeds directly on the sodium chloride surface as well as on the surrounding substrate due to evaporation of NaCl from the solid particle. The mechanism of this reaction could involve reaction in the vapor to produce Na2SO4 which then deposits, alternatively Na2SO4 could form directly on the substrate surface due to direct reaction there between the vapors NaCl, SO2 and O2.

  14. Workshop on moisture buffer capacity

    DEFF Research Database (Denmark)

    2003-01-01

    Summary report of a Nordtest workshop on moisture buffer capacity held at Copenhagen August 21-22 2003......Summary report of a Nordtest workshop on moisture buffer capacity held at Copenhagen August 21-22 2003...

  15. Synthesis of Gold Nanoparticles with Buffer-Dependent Variations of Size and Morphology in Biological Buffers

    Science.gov (United States)

    Ahmed, Syed Rahin; Oh, Sangjin; Baba, Rina; Zhou, Hongjian; Hwang, Sungu; Lee, Jaebeom; Park, Enoch Y.

    2016-02-01

    The demand for biologically compatible and stable noble metal nanoparticles (NPs) has increased in recent years due to their inert nature and unique optical properties. In this article, we present 11 different synthetic methods for obtaining gold nanoparticles (Au NPs) through the use of common biological buffers. The results demonstrate that the sizes, shapes, and monodispersity of the NPs could be varied depending on the type of buffer used, as these buffers acted as both a reducing agent and a stabilizer in each synthesis. Theoretical simulations and electrochemical experiments were performed to understand the buffer-dependent variations of size and morphology exhibited by these Au NPs, which revealed that surface interactions and the electrostatic energy on the (111) surface of Au were the determining factors. The long-term stability of the synthesized NPs in buffer solution was also investigated. Most NPs synthesized using buffers showed a uniquely wide range of pH stability and excellent cell viability without the need for further modifications.

  16. Investigation of graphene-on-metal substrates for SPR-based sensor using finite-difference time domain.

    Science.gov (United States)

    Said, Fairus Atida; Menon, Pulliyaseri Susthitha; Rajendran, Venkatachalam; Shaari, Sahbudin; Majlis, Burhanuddin Y

    2017-12-01

    In this study, the authors investigated the effects of a single layer graphene as a coating layer on top of metal thin films such as silver, gold, aluminum and copper using finite-difference time domain method. To enhance the resolution of surface plasmon resonance (SPR) sensor, it is necessary to increase the SPR reflectivity and decrease the full-width-half maximum (FWHM) of the SPR curve so that there is minimum uncertainty in the determination of the resonance dip. Numerical data was verified with analytical and experimental data where all the data were in good agreement with resonance angle differing in <10% due to noise present in components such as humidity and temperature. In further analysis, reflectivity and FWHM were compared among four types of metal with various thin film thicknesses where graphene was applied on top of the metal layers, and data was compared against pure conventional metal thin films. A 60 nm-thick Au thin film results in higher performance with reflectivity of 92.4% and FWHM of 0.88° whereas single layer graphene-on-60 nm-thick Au gave reflectivity of 91.7% and FWHM of 1.32°. However, a graphene-on-40 nm-thick Ag also gave good performance with narrower FWHM of 0.88° and reflection spectra of 89.2%.

  17. Propagation of misfit dislocations from buffer/Si interface into Si

    Science.gov (United States)

    Liliental-Weber, Zuzanna [El Sobrante, CA; Maltez, Rogerio Luis [Porto Alegre, BR; Morkoc, Hadis [Richmond, VA; Xie, Jinqiao [Raleigh, VA

    2011-08-30

    Misfit dislocations are redirected from the buffer/Si interface and propagated to the Si substrate due to the formation of bubbles in the substrate. The buffer layer growth process is generally a thermal process that also accomplishes annealing of the Si substrate so that bubbles of the implanted ion species are formed in the Si at an appropriate distance from the buffer/Si interface so that the bubbles will not migrate to the Si surface during annealing, but are close enough to the interface so that a strain field around the bubbles will be sensed by dislocations at the buffer/Si interface and dislocations are attracted by the strain field caused by the bubbles and move into the Si substrate instead of into the buffer epi-layer. Fabrication of improved integrated devices based on GaN and Si, such as continuous wave (CW) lasers and light emitting diodes, at reduced cost is thereby enabled.

  18. DNA Modified with Metal Nanoparticles: Preparation and Characterization of Ordered Metal-DNA Nanostructures in a Solution and on a Substrate

    Directory of Open Access Journals (Sweden)

    Nina Kasyanenko

    2016-01-01

    Full Text Available DNA interaction with silver and aluminum nanoparticles in a solution has been investigated with the AFM, SEM, dynamic light scattering, viscometry, and spectral methods. The comparison of DNA interaction with nanoparticles synthesized by the reduction of Ag+ ions and with nanoparticles obtained by the electric discharge plasma method was done. DNA metallization in a solution and on n-silicon surface with metal nanoparticles or by the reduction of silver ions after their binding to DNA was executed and studied. It was shown that DNA strands with regular location of silver or aluminum nanoparticles can be prepared. The conditions for the formation of silver nanoparticles and silver nanoclusters on DNA were analyzed.

  19. Novel chromogenic substrates with metal chelating properties for the histochemical detection of peroxidasic activity, derived from 3-amino-9-ethylcarbazole (AEC) and 3,6-diamino-9-ethylcarbazole.

    Science.gov (United States)

    Krieg, R; Halbhuber, K J; Oehring, H

    2000-11-01

    For staining of peroxidase activity routinely employed 3-amino-9-ethylcarbazole 1 (AEC) was chemically modified in order to obtain chromogenic enzyme substrates with improved staining properties. In conclusion of systematically structure/staining considerations of a series of novel substrates, it can be generalized that the performance of traditional chromogenic peroxidase amine-substrates is accessible an considerably improvement in terms of sensitivity and adaptibility for various application purposes (solubility and color of the reaction product, electron dense and osmiophilic properties, ...) by attachment of chelating N-benzyl-moieties making available highly efficient the well known metal catalytic effect in a proposed intramolecular way. Thus, the model compounds 3(arylmethyl)amino-9-ethyl-carbazole 4 and 3,6-bis-(arylmethyl)amino-9-ethyl-carbazole 7 were synthesized by condensation of 3-amino-9-ethylcarbazole 1 (AEC) or the corresponding 3,6-diamine 5 with aromatic aldehydes 2. The resulting Schiff bases 3 and 6 were subsequently reduced with sodium borohydride. The obtained benzylamines 4 and 7 were examined as chromogenic substrates: 1) qualitatively in test tube experiments concerning color, precipitation behavior and solubility of the precipitates, 2) quantitatively by means of electroblotted dilution series of horseradish peroxidase, and finally in a biological environment for the localization of endogenous peroxidasic activity 3) in native cryotome tissues of Wistar rats. 4) The usefulness of the new approach for electron microscopy was revealed, too. Thus the discrimination between internum and externum of specific granules after osmium tetroxide contrastate was higher if compared with results obtained by the Karnovsky protocol. The wide spread variation of substitution patterns of the novel reagents gave reason for structure-reactivity considerations and ongoing leading structures. The stereochemical and electronic factors as well as competing

  20. Epitaxial growth of znO nanowires over the ZnO thin films deposited on the Si and sapphire substrates.

    Science.gov (United States)

    Park, No-Kuk; Lee, You Jin; Jung, Ji Young; Lee, Won Guen; Bae, Young Je; Yoon, Suk Hoon; Han, Gi Bo; Ryu, Si Ok; Lee, Tae Jin

    2008-09-01

    Epitaxial growth of ZnO nanowires was carried out using a modified thermal evaporation method with inexpensive experimental setup. ZnO nanowires were synthesized using ZnO thin films. The ZnO thin films were deposited as a buffer layer on silicon and sapphire using an impinging flow reactor (IFR). The IFR system is a modified version of a chemical bath deposition (CBD). Films can be created at low temperature, without any metallic catalysts. The properties of Zinc Oxide films are dependant upon the type of substrate used. The same deposition process with a different substrates yields two films with different properties. The most critical effect on growth of ZnO nanowires were dependent the properties of the buffer layer deposited on the substrate. It was not the type of substrate used. A cost-efficient method for epitaxial growth of single crystal ZnO nanowires is proposed in this work.

  1. Modified Lanthanum Zirconium Oxide buffer layers for low-cost, high performance YBCO coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Parans Paranthaman, M., E-mail: paranthamanm@ornl.go [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Sathyamurthy, S.; Li, Xiaoping [American Superconductor Corporation, Devens, MA 01434 (United States); Specht, E.D.; Wee, S.H.; Cantoni, C.; Goyal, A. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Rupich, M.W. [American Superconductor Corporation, Devens, MA 01434 (United States)

    2010-03-01

    The pyrochlore Lanthanum Zirconium Oxide, La{sub 2}Zr{sub 2}O{sub 7} (LZO), has been developed as a potential replacement barrier layer in the standard RABiTS three-layer architecture of physical vapor deposited CeO{sub 2} cap/YSZ barrier/Y{sub 2}O{sub 3} seed on Ni-5%W metal tape. The main focus of this research is to ascertain whether: (i) we can further improve the barrier properties of LZO; (ii) we can modify the LZO cation ratio and still achieve a high level of performance; and (iii) it is possible to reduce the number of buffer layers. We report a systematic investigation of the LZO film growth with varying compositions of La:Zr ratio in the La{sub 2}O{sub 3}-ZrO{sub 2} system. Using a metal-organic deposition (MOD) process, we have grown smooth, crack-free, epitaxial thin films of La{sub x}Zr{sub 1-x}O{sub y} (x = 0.2-0.6) on standard Y{sub 2}O{sub 3} buffered Ni-5W substrates in short lengths. Detailed XRD studies indicate that a single epitaxial LZO phase with only (0 0 1) texture can be achieved in a broad compositional range of x = 0.2-0.6 in La{sub x}Zr{sub 1-x}O{sub y}. Both CeO{sub 2} cap layers and MOD-YBCO films were grown epitaxially on these modified LZO barriers. High critical currents per unit width, I{sub c} of 274-292 A/cm at 77 K and self-field were achieved for MOD-YBCO films grown on La{sub x}Zr{sub 1-x}O{sub y} (x 0.4-0.6) films. These results indicate that LZO films can be grown with a broad compositional range and still support high performance YBCO coated conductors. In addition, epitaxial MOD La{sub x}Zr{sub 1-x}O{sub y} (x = 0.25) films were grown directly on biaxially textured Ni-3W substrates. About 3 mum thick YBCO films grown on a single MOD-LZO buffered Ni-3W substrates using pulsed laser deposition show a critical current density, J{sub c}, of 0.55 MA/cm{sup 2} (I{sub c} of 169 A/cm) at 77 K and 0.01 T. This work holds promise for a route for producing simplified buffer architecture for RABiTS based YBCO coated conductors.

  2. Low turn-on and uniform field emission from structurally engineered carbon nanotube arrays through growth on metal wire mesh substrates

    Science.gov (United States)

    Chen, Guohai; Zhao, Bin; Kimura, Hiroe; Kurachi, Hiroyuki; Matsumoto, Naoyuki; Yamada, Takeo; Hata, Kenji; Uemura, Sashiro; Futaba, Don N.

    2017-10-01

    A simple and novel approach to improve the field emission properties from carbon nanotube (CNT) arrays is presented through the direct growth of CNTs onto metal wire mesh substrates. We utilized the curvilinear profiles of the wires to create a cleaved CNT array structure, which was uniformly distributed throughout the entire emitter array area. Investigation of the factors governing the emission properties showed that increased wire diameter, increased CNT array height, and decreased catalyst thickness led to decreased turn-on fields (TOFs) within our experimental range. In addition, we found that the underlying mechanism explaining these empirical results stemmed from the creation of sharp edges which were sufficiently spaced and homogeneously distributed throughout the emitter array. Through this method, a low TOF of ~0.95 V µm‑1 for a 10 µA cm‑2 emission current density was achieved, which is among the lowest values reported for field emission arrays.

  3. Deposition of Metal-Organic Frameworks by Liquid-Phase Epitaxy: The Influence of Substrate Functional Group Density on Film Orientation

    Directory of Open Access Journals (Sweden)

    Christof Wöll

    2012-09-01

    Full Text Available The liquid phase epitaxy (LPE of the metal-organic framework (MOF HKUST-1 has been studied for three different COOH-terminated templating organic surfaces prepared by the adsorption of self-assembled monolayers (SAMs on gold substrates. Three different SAMs were used, mercaptohexadecanoic acid (MHDA, 4’-carboxyterphenyl-4-methanethiol (TPMTA and 9-carboxy-10-(mercaptomethyltriptycene (CMMT. The XRD data demonstrate that highly oriented HKUST-1 SURMOFs with an orientation along the (100 direction was obtained on MHDA-SAMs. In the case of the TPMTA-SAM, the quality of the deposited SURMOF films was found to be substantially inferior. Surprisingly, for the CMMT-SAMs, a different growth direction was obtained; XRD data reveal the deposition of highly oriented HKUST-1 SURMOFs grown along the (111 direction.

  4. Deposition of Metal-Organic Frameworks by Liquid-Phase Epitaxy: The Influence of Substrate Functional Group Density on Film Orientation

    Science.gov (United States)

    Liu, Jinxuan; Shekhah, Osama; Stammer, Xia; Arslan, Hasan K.; Liu, Bo; Schüpbach, Björn; Terfort, Andreas; Wöll, Christof

    2012-01-01

    The liquid phase epitaxy (LPE) of the metal-organic framework (MOF) HKUST-1 has been studied for three different COOH-terminated templating organic surfaces prepared by the adsorption of self-assembled monolayers (SAMs) on gold substrates. Three different SAMs were used, mercaptohexadecanoic acid (MHDA), 4’-carboxyterphenyl-4-methanethiol (TPMTA) and 9-carboxy-10-(mercaptomethyl)triptycene (CMMT). The XRD data demonstrate that highly oriented HKUST-1 SURMOFs with an orientation along the (100) direction was obtained on MHDA-SAMs. In the case of the TPMTA-SAM, the quality of the deposited SURMOF films was found to be substantially inferior. Surprisingly, for the CMMT-SAMs, a different growth direction was obtained; XRD data reveal the deposition of highly oriented HKUST-1 SURMOFs grown along the (111) direction.

  5. Deposition of metal-organic frameworks by liquid-phase epitaxy: The influence of substrate functional group density on film orientation

    KAUST Repository

    Liu, J.

    2012-09-05

    The liquid phase epitaxy (LPE) of the metal-organic framework (MOF) HKUST-1 has been studied for three different COOH-terminated templating organic surfaces prepared by the adsorption of self-assembled monolayers (SAMs) on gold substrates. Three different SAMs were used, mercaptohexadecanoic acid (MHDA), 4\\'-carboxyterphenyl-4-methanethiol (TPMTA) and 9-carboxy-10-(mercaptomethyl)triptycene (CMMT). The XRD data demonstrate that highly oriented HKUST-1 SURMOFs with an orientation along the (100) direction was obtained on MHDA-SAMs. In the case of the TPMTA-SAM, the quality of the deposited SURMOF films was found to be substantially inferior. Surprisingly, for the CMMT-SAMs, a different growth direction was obtained; XRD data reveal the deposition of highly oriented HKUST-1 SURMOFs grown along the (111) direction.

  6. Precise Placement of Metallic Nanowires on a Substrate by Localized Electric Fields and Inter-Nanowire Electrostatic Interaction

    Directory of Open Access Journals (Sweden)

    U Hyeok Choi

    2017-10-01

    Full Text Available Placing nanowires at the predetermined locations on a substrate represents one of the significant hurdles to be tackled for realization of heterogeneous nanowire systems. Here, we demonstrate spatially-controlled assembly of a single nanowire at the photolithographically recessed region at the electrode gap with high integration yield (~90%. Two popular routes, such as protruding electrode tips and recessed wells, for spatially-controlled nanowire alignment, are compared to investigate long-range dielectrophoretic nanowire attraction and short-range nanowire-nanowire electrostatic interaction for determining the final alignment of attracted nanowires. Furthermore, the post-assembly process has been developed and tested to make a robust electrical contact to the assembled nanowires, which removes any misaligned ones and connects the nanowires to the underlying electrodes of circuit.

  7. Paramagnetic iron-doped hydroxyapatite nanoparticles with improved metal sorption properties. A bioorganic substrates-mediated synthesis.

    Science.gov (United States)

    Mercado, D Fabio; Magnacca, Giuliana; Malandrino, Mery; Rubert, Aldo; Montoneri, Enzo; Celi, Luisella; Bianco Prevot, Alessandra; Gonzalez, Mónica C

    2014-03-26

    This paper describes the synthesis of paramegnetic iron-containing hydroxyapatite nanoparticles and their increased Cu(2+) sorbent capacity when using Ca(2+) complexes of soluble bioorganic substrates from urban wastes as synthesis precursors. A thorough characterization of the particles by TEM, XRD, FTIR spectroscopy, specific surface area, TGA, XPS, and DLS indicates that loss of crystallinity, a higher specific area, an increased surface oxygen content, and formation of surface iron phases strongly enhance Cu(2+) adsorption capacity of hydroxyapatite-based materials. However, the major effect of the surface and morphologycal modifications is the size diminution of the aggregates formed in aqueous solutions leading to an increased effective surface available for Cu(2+) adsorption. Maximum sorption values of 550-850 mg Cu(2+) per gram of particles suspended in an aqueous solution at pH 7 were determined, almost 10 times the maximum values observed for hydroxyapatite nanoparticles suspensions under the same conditions.

  8. Stress in (Al, Ga)N heterostructures grown on 6H-SiC and Si substrates byplasma-assisted molecular beam epitaxy

    Science.gov (United States)

    Koshelev, O. A.; Nechaev, D. V.; Sitnikova, A. A.; Ratnikov, V. V.; Ivanov, S. V.; Jmerik, V. N.

    2017-11-01

    The paper describes experimental results on low temperature plasma-assisted molecular beam epitaxy of GaN/AlN heterostructures on both 6H-SiC and Si(111) substrates. We demonstrate that application of migration enhanced epitaxy and metal-modulated epitaxy for growth of AlN nucleation and buffer layers lowers the screw and edge(total)threading dislocation (TD) densities down to 1.7·108 and 2·109 cm-2, respectively, in a 2.8-μm-thick GaN buffer layer grown atop of AlN/6H-SiC. The screw and total TD densities of 1.2·109 and 7.4·109 cm-2, respectively, were achieved in a 1-μm-thickGaN/AlNheterostructure on Si(111). Stress generation and relaxation in GaN/AlN heterostructures were investigated by using multi-beam optical stress sensor (MOSS) to achieve zero substrate curvature at room temperature. It is demonstrated that a 1-μm-thick GaN/AlN buffer layer grown by PA MBE provides planar substrate morphology in the case of growth on Si substrates whereas 5-μm-thick GaN buffer layers have to be used to achieve the same when growing on 6H-SiC substrates.

  9. Numerical study of melted particles crush metallic substrates and the interaction between particles and a plasma beam in the thermal projection process

    Energy Technology Data Exchange (ETDEWEB)

    Kriba, Ilhem [Plasma Laboratory, Faculty of Sciences, Department of Physics, University of Ouargla, Ouargla (Algeria)], E-mail: ilhem_kriba@yahoo.fr; Djebaili, A. [Laboratory of Chemistry and Environment Chemistry L.C.C.E, University of Batna (Algeria)

    2009-03-01

    Plasma spray processes have been widely used to produce high performance coatings of a wide range of materials (metallic, non-metallic, and ceramics), offering protection from, e.g. wear, extreme temperature, chemical attack and environmental corrosion. To obtain good quality coatings, spray parameters must be carefully selected. Due to the large variety in process parameters, it is difficult to optimize the process for each specific coating and substrate combinations. Furthermore modelling the spray process allows a better understanding of the process sequences during thermal spraying. The simulation of coating formation to estimate the process parameters is an important tool to develop new coating structures with defined properties. In this work, the process of plasma sprayed coating has been analyzed by numerical simulation. Commercial code is used to predict the plasma jet characteristics, plasma-particle interaction, and coating formation. Using this model we can obtain coating microstructure and characteristics which form a foundation for further improvement of an advanced ceramic coating build up model.

  10. Influence of Substrate on Crystal Orientation of Large-Grained Si Thin Films Formed by Metal-Induced Crystallization

    Directory of Open Access Journals (Sweden)

    Kaoru Toko

    2015-01-01

    Full Text Available Producing large-grained polycrystalline Si (poly-Si film on glass substrates coated with conducting layers is essential for fabricating Si thin-film solar cells with high efficiency and low cost. We investigated how the choice of conducting underlayer affected the poly-Si layer formed on it by low-temperature (500°C Al-induced crystallization (AIC. The crystal orientation of the resulting poly-Si layer strongly depended on the underlayer material: (100 was preferred for Al-doped-ZnO (AZO and indium-tin-oxide (ITO; (111 was preferred for TiN. This result suggests Si heterogeneously nucleated on the underlayer. The average grain size of the poly-Si layer reached nearly 20 µm for the AZO and ITO samples and no less than 60 µm for the TiN sample. Thus, properly electing the underlayer material is essential in AIC and allows large-grained Si films to be formed at low temperatures with a set crystal orientation. These highly oriented Si layers with large grains appear promising for use as seed layers for Si light-absorption layers as well as for advanced functional materials.

  11. Buffer capacity of biologics--from buffer salts to buffering by antibodies.

    Science.gov (United States)

    Karow, Anne R; Bahrenburg, Sven; Garidel, Patrick

    2013-01-01

    Controlling pH is essential for a variety of biopharmaceutical process steps. The chemical stability of biologics such as monoclonal antibodies is pH-dependent and slightly acidic conditions are favorable for stability in a number of cases. Since control of pH is widely provided by added buffer salts, the current study summarizes the buffer characteristics of acetate, citrate, histidine, succinate, and phosphate buffers. Experimentally derived values largely coincide with values calculated from a model that had been proposed in 1922 by van Slyke. As high concentrated protein formulations become more and more prevalent for biologics, the self-buffering potential of proteins becomes of relevance. The current study provides information on buffer characteristics for pH ranges down to 4.0 and up to 8.0 and shows that a monoclonal antibody at 50 mg/mL exhibits similar buffer capacity as 6 mM citrate or 14 mM histidine (pH 5.0-6.0). Buffer capacity of antibody solutions scales linearly with protein concentration up to more than 200 mg/mL. At a protein concentration of 220 mg/mL, the buffer capacity resembles the buffer capacity of 30 mM citrate or 50 mM histidine (pH 5.0-6.0). The buffer capacity of monoclonal antibodies is practically identical at the process relevant temperatures 5, 25, and 40°C. Changes in ionic strength of ΔI=0.15, in contrast, can alter the buffer capacity up to 35%. In conclusion, due to efficient self-buffering by antibodies in the pH range of favored chemical stability, conventional buffer excipients could be dispensable for pH stabilization of high concentrated protein solutions. Copyright © 2013 American Institute of Chemical Engineers.

  12. The Lazy Z-Buffer

    OpenAIRE

    Hill, Steve

    1994-01-01

    This paper describes a new perspective on a fundamental algorithm of three-dimensional computer graphics, namely z-buffering. An implementation of the z-buffer method in a lazy functional language behaves in a quite different manner to the traditional imperative counterpart. The main result of this paper is to show that the lazy z-buffer is a scan-line method. The effective difference between scan-line methods and z-buffers is one of order of evaluation. A hybrid algorithm with properties com...

  13. Facile Formation of High-quality InGaN/GaN Quantum-disks-in-Nanowires on Bulk-Metal Substrates for High-power Light-emitters

    KAUST Repository

    Zhao, Chao

    2016-01-08

    High-quality nitride materials grown on scalable and low-cost metallic substrates are considerably attractive for high-power light emitters. We demonstrate here, for the first time, the high-power red (705 nm) InGaN/GaN quantum-disks (Qdisks)-in-nanowire light-emitting diodes (LEDs) self-assembled directly on metal-substrate. The LEDs exhibited a low turn-on voltage of ~2 V without efficiency droop up to injection current of 500 mA (1.6 kA/cm2) at ~5 V. This is achieved through the direct growth and optimization of high-quality nanowires on titanium (Ti) coated bulk polycrystalline-molybdenum (Mo) substrates. We performed extensive studies on the growth mechanisms, obtained high-crystal-quality nanowires, and confirmed the epitaxial relationship between the cubic titanium nitride (TiN) transition layer and the hexagonal nanowires. The growth of nanowires on all-metal stack of TiN/Ti/Mo enables simultaneous implementation of n-metal contact, reflector and heat-sink, which greatly simplifies the fabrication process of high-power light emitters. Our work ushers in a practical platform for high-power nanowires light emitters, providing versatile solutions for multiple cross-disciplinary applications that are greatly enhanced by leveraging on the chemical stability of nitride materials, large specific surface of nanowires, chemical lift-off ready layer structures, and reusable Mo substrates.

  14. Mechanisms of buffer therapy resistance

    Directory of Open Access Journals (Sweden)

    Kate M. Bailey

    2014-04-01

    Full Text Available Many studies have shown that the acidity of solid tumors contributes to local invasion and metastasis. Oral pH buffers can specifically neutralize the acidic pH of tumors and reduce the incidence of local invasion and metastatic formation in multiple murine models. However, this effect is not universal as we have previously observed that metastasis is not inhibited by buffers in some tumor models, regardless of buffer used. B16-F10 (murine melanoma, LL/2 (murine lung and HCT116 (human colon tumors are resistant to treatment with lysine buffer therapy, whereas metastasis is potently inhibited by lysine buffers in MDA-MB-231 (human breast and PC3M (human prostate tumors. In the current work, we confirmed that sensitive cells utilized a pH-dependent mechanism for successful metastasis supported by a highly glycolytic phenotype that acidifies the local tumor microenvironment resulting in morphological changes. In contrast, buffer-resistant cell lines exhibited a pH-independent metastatic mechanism involving constitutive secretion of matrix degrading proteases without elevated glycolysis. These results have identified two distinct mechanisms of experimental metastasis, one of which is pH-dependent (buffer therapy sensitive cells and one which is pH-independent (buffer therapy resistant cells. Further characterization of these models has potential for therapeutic benefit.

  15. Mechanisms of buffer therapy resistance.

    Science.gov (United States)

    Bailey, Kate M; Wojtkowiak, Jonathan W; Cornnell, Heather H; Ribeiro, Maria C; Balagurunathan, Yoganand; Hashim, Arig Ibrahim; Gillies, Robert J

    2014-04-01

    Many studies have shown that the acidity of solid tumors contributes to local invasion and metastasis. Oral pH buffers can specifically neutralize the acidic pH of tumors and reduce the incidence of local invasion and metastatic formation in multiple murine models. However, this effect is not universal as we have previously observed that metastasis is not inhibited by buffers in some tumor models, regardless of buffer used. B16-F10 (murine melanoma), LL/2 (murine lung) and HCT116 (human colon) tumors are resistant to treatment with lysine buffer therapy, whereas metastasis is potently inhibited by lysine buffers in MDA-MB-231 (human breast) and PC3M (human prostate) tumors. In the current work, we confirmed that sensitive cells utilized a pH-dependent mechanism for successful metastasis supported by a highly glycolytic phenotype that acidifies the local tumor microenvironment resulting in morphological changes. In contrast, buffer-resistant cell lines exhibited a pH-independent metastatic mechanism involving constitutive secretion of matrix degrading proteases without elevated glycolysis. These results have identified two distinct mechanisms of experimental metastasis, one of which is pH-dependent (buffer therapy sensitive cells) and one which is pH-independent (buffer therapy resistant cells). Further characterization of these models has potential for therapeutic benefit. Copyright © 2014 Neoplasia Press, Inc. Published by Elsevier Inc. All rights reserved.

  16. Modified Lanthanum Zirconium Oxide Buffer for Low-Cost, High Performance YBCO Coated Conductors

    Energy Technology Data Exchange (ETDEWEB)

    Paranthaman, Mariappan Parans [ORNL; Sathyamurthy, Srivatsan [ORNL; Li, Xiaoping [American Superconductor Corporation, Westborough, MA; Specht, Eliot D [ORNL; Wee, Sung Hun [ORNL; Cantoni, Claudia [ORNL; Goyal, Amit [ORNL; Rupich, M. W. [American Superconductor Corporation, Westborough, MA

    2010-01-01

    Lanthanum Zirconium Oxide, La2Zr2O7 (LZO) has been developed as a potential replacement barrier layer in the standard RABiTS three-layer architecture of physical vapor deposited CeO2 cap/YSZ barrier/Y2O3 seed/Ni-5W. The main focus of this research is to see (i) whether we can improve further the barrier properties of LZO; (ii) can we widen the LZO composition and still achieve the high performance?; and (iii) is it possible to reduce the number of buffer layers? We report a systematic investigation of the LZO film growth with varying compositions of La:Zr ratio in the La2O3-ZrO2 system. Using metal-organic deposition (MOD) process, we have grown smooth, crack-free, epitaxial thin films of LaxZr1-xOy (x = 0.2-0.6) on standard Y2O3 buffered Ni-5W substrates in short lengths. Detailed XRD studies indicate that a single epitaxial LZO phase without the (111) texture can be achieved in a wider compositional window of x = 0.2-0.6 in LaxZr1-xOy. Both CeO2 cap layers and MOD-YBCO films were grown 2 epitaxially on these modified LZO barriers. Transport property measurements indicate that we can achieve a higher critical current, Ic of 274-292 A/cm at 77 K and self-field on MOD-YBCO films grown on LaxZr1-xOy (x = 0.4-0.6) films. These results indicate that LZO films can be grown with a wider compositional window and still achieve high performance YBCO coated conductors. In addition, epitaxial MOD LaxZr1-xOy (x = 0.25) films were grown directly on biaxially textured Ni-3W substrates. About 3 m thick YBCO films with a Jc of 0.55 MA/cm2 at 77 K and 0.01 T were grown on a single MOD LZO buffered Ni-3W substrate using pulsed laser deposition. This work promises a route for producing simplified buffer architecture for RABiTS based YBCO coated conductors.

  17. Nitrification in a zeoponic substrate

    Science.gov (United States)

    McGilloway, R. L.; Weaver, R. W.; Ming, D. W.; Gruener, J. E.

    2003-01-01

    Clinoptilolite is a zeolite mineral with high cation exchange capacity used in zeoponic substrates that have been proposed as a solid medium for growing plants or as a fertilizer material. The kinetics of nitrification has not been measured for NH4+ saturated zeoponic substrate. Experiments were conducted to evaluate the production of NO2- and NO3-, and nitrifier populations in zeoponic substrates. Small columns were filled with zeoponic substrate inoculated with a commercial inoculum or soil enrichment culture of nitrifying bacteria. In addition to column studies, a growth chamber study was conducted to evaluate the kinetics of nitrification in zeoponic substrates used to grow radishes (Raphanus sativus L.). The zeoponic substrate provided a readily available source of NH4+, and nitrifying bacteria were active in the substrate. Ammonium oxidation rates in column studies ranged from 5 to 10 micrograms N g-1 substrate h-1, and NO2- oxidation rates were 2 to 9.5 micrograms N g-1 substrate h-1. Rates determined from the growth chamber study were approximately 1.2 micrograms N g-1 substrate h-1. Quantities of NH4+ oxidized to NO2- and NO3- in inoculated zeoponic substrate were in excess of plant up-take. Acidification as a result of NH4+ oxidation resulted in a pH decline, and the zeoponic substrate showed limited buffering capacity.

  18. Using fractional order method to generalize strengthening generating operator buffer operator and weakening buffer operator

    OpenAIRE

    Wu, L.; Liu, S.; Yang, Yingjie

    2016-01-01

    Traditional integer order buffer operator is extended to fractional order buffer operator, the corresponding relationship between the weakening buffer operator and the strengthening buffer operator is revealed. Fractional order buffer operator not only can generalize the weakening buffer operator and the strengthening buffer operator, but also realize tiny adjustment of buffer effect. The effectiveness of GM(1,1) with the fractional order buffer operator is validated by six cases.

  19. Heuristics for the Buffer Allocation Problem with Collision Probability Using Computer Simulation

    Directory of Open Access Journals (Sweden)

    Eishi Chiba

    2015-01-01

    Full Text Available The standard manufacturing system for Flat Panel Displays (FPDs consists of a number of pieces of equipment in series. Each piece of equipment usually has a number of buffers to prevent collision between glass substrates. However, in reality, very few of these buffers seem to be used. This means that redundant buffers exist. In order to reduce cost and space necessary for manufacturing, the number of buffers should be minimized with consideration of possible collisions. In this paper, we focus on an in-line system in which each piece of equipment can have any number of buffers. In this in-line system, we present a computer simulation method for the computation of the probability of a collision occurring. Based on this method, we try to find a buffer allocation that achieves the smallest total number of buffers under an arbitrarily specified collision probability. We also implement our proposed method and present some computational results.

  20. Evaluation of methods for application of epitaxial buffer and superconductor layers

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-30

    The recent achievements of critical currents exceeding million amperes per square centimeter at 77K in YBCO deposited over suitably textured substrate have stimulated interest in the potential applications of coated conductors at high temperatures and in high magnetic fields. Currently, ion-beam assisted deposition (IBAD), and rolling assisted bi-axially textured substrate (RABiTS), represent two available options for obtaining textured substrates. For applying suitable coatings of buffer and high temperature superconductor (HTS) material over textured substrates, several options are available which include sputtering, electron-beam evaporation, laser ablation, electrophoresis, chemical vapor deposition (including metal organics chemical vapor deposition), sol-gel, metal organics decomposition, electrodeposition and aerosol/spray pyrolysis. A commercial continuous long-length wire/tape manufacturing scheme developed out of any suitable combination of the above techniques would consist of operations involving preparation of the substrate and application of buffer, HTS and passivation/insulation materials and special treatment steps such as post-annealing. These operations can be effected by various process parameters that can be classified into chemistry, materials, engineering and environmental related parameters. Under the DOE-sponsored program, to carry out an engineering evaluation, first, the process flow schemes were developed for various candidate options identifying the major operating steps, process conditions, and process streams. Next, to evaluate quantifiable parameters such as process severity (e.g. temperature and pressure), coating thickness and deposition rate for HTS material, achieved maximum J{sub c} value (for films >1{micro}m thick) and cost of chemical and material utilization efficiency, the multi-attribute method was used to determine attributes/merits for various parameters and candidate options. To determine similar attribute values for the

  1. Variation of power generation at different buffer types and conductivities in single chamber microbial fuel cells

    KAUST Repository

    Nam, Joo-Youn

    2010-01-15

    Microbial fuel cells (MFCs) are operated with solutions containing various chemical species required for the growth of electrochemically active microorganisms including nutrients and vitamins, substrates, and chemical buffers. Many different buffers are used in laboratory media, but the effects of these buffers and their inherent electrolyte conductivities have not been examined relative to current generation in MFCs. We investigated the effect of several common buffers (phosphate, MES, HEPES, and PIPES) on power production in single chambered MFCs compared to a non-buffered control. At the same concentrations the buffers produced different solution conductivities which resulted in different ohmic resistances and power densities. Increasing the solution conductivities to the same values using NaCl produced comparable power densities for all buffers. Very large increases in conductivity resulted in a rapid voltage drop at high current densities. Our results suggest that solution conductivity at a specific pH for each buffer is more important in MFC studies than the buffer itself given relatively constant pH conditions. Based on our analysis of internal resistance and a set neutral pH, phosphate and PIPES are the most useful buffers of those examined here because pH was maintained close to the pKa of the buffer, maximizing the ability of the buffer to contribute to increase current generation at high power densities. © 2009 Elsevier B.V. All rights reserved.

  2. Variation of power generation at different buffer types and conductivities in single chamber microbial fuel cells.

    Science.gov (United States)

    Nam, Joo-Youn; Kim, Hyun-Woo; Lim, Kyeong-Ho; Shin, Hang-Sik; Logan, Bruce E

    2010-01-15

    Microbial fuel cells (MFCs) are operated with solutions containing various chemical species required for the growth of electrochemically active microorganisms including nutrients and vitamins, substrates, and chemical buffers. Many different buffers are used in laboratory media, but the effects of these buffers and their inherent electrolyte conductivities have not been examined relative to current generation in MFCs. We investigated the effect of several common buffers (phosphate, MES, HEPES, and PIPES) on power production in single chambered MFCs compared to a non-buffered control. At the same concentrations the buffers produced different solution conductivities which resulted in different ohmic resistances and power densities. Increasing the solution conductivities to the same values using NaCl produced comparable power densities for all buffers. Very large increases in conductivity resulted in a rapid voltage drop at high current densities. Our results suggest that solution conductivity at a specific pH for each buffer is more important in MFC studies than the buffer itself given relatively constant pH conditions. Based on our analysis of internal resistance and a set neutral pH, phosphate and PIPES are the most useful buffers of those examined here because pH was maintained close to the pK(a) of the buffer, maximizing the ability of the buffer to contribute to increase current generation at high power densities. Copyright 2009 Elsevier B.V. All rights reserved.

  3. Influence of the RNase H domain of retroviral reverse transcriptases on the metal specificity and substrate selection of their polymerase domains

    Directory of Open Access Journals (Sweden)

    Pandey Virendra N

    2009-10-01

    Full Text Available Abstract Reverse transcriptases from HIV-1 and MuLV respectively prefer Mg2+ and Mn2+ for their polymerase activity, with variable fidelity, on both RNA and DNA templates. The function of the RNase H domain with respect to these parameters is not yet understood. To evaluate this function, two chimeric enzymes were constructed by swapping the RNase H domains between HIV-1 RT and MuLV RT. Chimeric HIV-1 RT, having the RNase H domain of MuLV RT, inherited the divalent cation preference characteristic of MuLV RT on the DNA template with no significant change on the RNA template. Chimeric MuLV RT, likewise partially inherited the metal ion preference of HIV-1 RT. Unlike the wild-type MuLV RT, chimeric MuLV RT is able to use both Mn.dNTP and Mg.dNTP on the RNA template with similar efficiency, while a 30-fold higher preference for Mn.dNTP was seen on the DNA template. The metal preferences for the RNase H activity of chimeric HIV-1 RT and chimeric MuLV RT were, respectively, Mn2+ and Mg2+, a property acquired through their swapped RNase H domains. Chimeric HIV-1 RT displayed higher fidelity and discrimination against rNTPs than against dNTPs substrates, a property inherited from MuLV RT. The overall fidelity of the chimeric MuLV RT was decreased in comparison to the parental MuLV RT, suggesting that the RNase H domain profoundly influences the function of the polymerase domain.

  4. Highly textured Gd2Zr2O7 films grown on textured Ni-5 at.%W substrates by solution deposition route: Growth, texture evolution, and microstructure dependency

    DEFF Research Database (Denmark)

    Yue, Zhao; Grivel, Jean-Claude; Napari, M.

    2012-01-01

    or crystallization in the thicker films. This work not only demonstrates a route for producing textured Gd2Zr2O7 buffer layers with dense structure directly on technical substrates, but also provides some fundamental understandings related to chemical solution derived films grown on metallic substrates.......Growth, texture evolution and microstructure dependency of solution derived Gd2Zr2O7 films deposited on textured Ni-5 at.%W substrates have been extensively studied. Influence of processing parameters, in particular annealing temperature and dwell time, as well as thickness effect on film texture...... the difference of interfacial energy along two directions in the anisotropic metallic substrate. Growth of Gd2Zr2O7 films displays an ultrafast kinetics under optimized conditions. Independency of sharp epitaxial (004) and polycrystalline (222) orientation is revealed from further synchrotron diffraction studies...

  5. Effect of Two-Step Metal Organic Chemical Vapor Deposition Growth on Quality, Diameter and Density of InAs Nanowires on Si (111) Substrate

    Science.gov (United States)

    Yu, Hung Wei; Anandan, Deepak; Hsu, Ching Yi; Hung, Yu Chih; Su, Chun Jung; Wu, Chien Ting; Kakkerla, Ramesh Kumar; Ha, Minh Thien Huu; Huynh, Sa Hoang; Tu, Yung Yi; Chang, Edward Yi

    2017-10-01

    High-density (˜ 80/um2) vertical InAs nanowires (NWs) with small diameters (˜ 28 nm) were grown on bare Si (111) substrates by means of two-step metal organic chemical vapor deposition. There are two critical factors in the growth process: (1) a critical nucleation temperature for a specific In molar fraction (approximately 1.69 × 10-5 atm) is the key factor to reduce the size of the nuclei and hence the diameter of the InAs NWs, and (2) a critical V/III ratio during the 2nd step growth will greatly increase the density of the InAs NWs (from 45 μm-2 to 80 μm-2) and at the same time keep the diameter small. The high-resolution transmission electron microscopy and selected area diffraction patterns of InAs NWs grown on Si exhibit a Wurtzite structure and no stacking faults. The observed longitudinal optic peaks in the Raman spectra were explained in terms of the small surface charge region width due to the small NW diameter and the increase of the free electron concentration, which was consistent with the TCAD program simulation of small diameter (< 40 nm) InAs NWs.

  6. One-shot deep-UV pulsed-laser-induced photomodification of hollow metal nanoparticles for high-density data storage on flexible substrates.

    Science.gov (United States)

    Wan, Dehui; Chen, Hsuen-Li; Tseng, Shao-Chin; Wang, Lon A; Chen, Yung-Pin

    2010-01-26

    In this paper, we report a new optical data storage method: photomodification of hollow gold nanoparticle (HGN) monolayers induced by one-shot deep-ultraviolet (DUV) KrF laser recording. As far as we are aware, this study is the first to apply HGNs in optical data storage and also the first to use a recording light source for the metal nanoparticles (NPs) that is not a surface plasmon resonance (SPR) wavelength. The short wavelength of the recording DUV laser improved the optical resolution dramatically. We prepared HGNs exhibiting two absorbance regions: an SPR peak in the near-infrared (NIR) region and an intrinsic material extinction in the DUV region. A single pulse from a KrF laser heated the HGNs and transformed them from hollow structures to smaller solid spheres. This change in morphology for the HGNs was accompanied by a significant blue shift of the SPR peak. Employing this approach, we demonstrated its patterning ability with a resolving power of a half-micrometer (using a phase mask) and developed a readout method (using a blue-ray laser microscope). Moreover, we prepared large-area, uniform patterns of monolayer HGNs on various substrates (glass slides, silicon wafers, flexible plates). If this spectral recording technique could be applied onto thin flexible tapes, the recorded data density would increase significantly relative to that of current rigid discs (e.g., compact discs).

  7. X-ray Crystallographic Studies of Substrate Binding to Aristolochene Synthase Suggest a Metal Ion Binding Sequence for Catalysis*S⃞

    Science.gov (United States)

    Shishova, Ekaterina Y.; Yu, Fanglei; Miller, David J.; Faraldos, Juan A.; Zhao, Yuxin; Coates, Robert M.; Allemann, Rudolf K.; Cane, David E.; Christianson, David W.

    2008-01-01

    The universal sesquiterpene precursor, farnesyl diphosphate (FPP), is cyclized in an Mg2+-dependent reaction catalyzed by the tetrameric aristolochene synthase from Aspergillus terreus to form the bicyclic hydrocarbon aristolochene and a pyrophosphate anion (PPi) coproduct. The 2.1-Å resolution crystal structure determined from crystals soaked with FPP reveals the binding of intact FPP to monomers A-C, and the binding of PPi and Mg2+B to monomer D. The 1.89-Å resolution structure of the complex with 2-fluorofarnesyl diphosphate (2F-FPP) reveals 2F-FPP binding to all subunits of the tetramer, with Mg2+Baccompanying the binding of this analogue only in monomer D. All monomers adopt open activesite conformations in these complexes, but slight structural changes in monomers C and D of each complex reflect the very initial stages of a conformational transition to the closed state. Finally, the 2.4-Å resolution structure of the complex with 12,13-difluorofarnesyl diphosphate (DF-FPP) reveals the binding of intact DF-FPP to monomers A-C in the open conformation and the binding of PPi, Mg2+B, and Mg2+C to monomer D in a predominantly closed conformation. Taken together, these structures provide 12 independent “snapshots” of substrate or product complexes that suggest a possible sequence for metal ion binding and conformational changes required for catalysis. PMID:18385128

  8. Electrodialysis operation with buffer solution

    Science.gov (United States)

    Hryn, John N [Naperville, IL; Daniels, Edward J [Orland Park, IL; Krumdick, Greg K [Crete, IL

    2009-12-15

    A new method for improving the efficiency of electrodialysis (ED) cells and stacks, in particular those used in chemical synthesis. The process entails adding a buffer solution to the stack for subsequent depletion in the stack during electrolysis. The buffer solution is regenerated continuously after depletion. This buffer process serves to control the hydrogen ion or hydroxide ion concentration so as to protect the active sites of electrodialysis membranes. The process enables electrodialysis processing options for products that are sensitive to pH changes.

  9. Impact of substrate contamination with mycotoxins, heavy metals and pesticides on the growth performance and composition of black soldier fly larvae (Hermetia illucens) for use in the feed and food value chain.

    Science.gov (United States)

    Purschke, Benedict; Scheibelberger, Rafaela; Axmann, Sonja; Adler, Andreas; Jäger, Henry

    2017-08-01

    Edible insects have emerged as an alternative and sustainable source of high-quality, animal-derived protein and fat for livestock production or direct human nutrition. During the production of insects, substrate quality is a key parameter to assure optimal insect biomass gain as well as the safety of feed and food derived from commercially reared insects. Therefore, the influence of a realistic substrate contamination scenario on growth performance and accumulation behaviour of black soldier fly larvae (BSFL; Hermetia illucens L.) was investigated. Newly hatched larvae were fed on a corn-based substrate spiked with heavy metals (As, Cd, Cr, Hg, Ni, Pb), mycotoxins (aflatoxins B1/B2/G2, deoxynivalenol, ochratoxin A, zearalenone) and pesticides (chlorpyrifos, chlorpyrifos-methyl, pirimiphos-methyl) under defined breeding conditions (10 days, 28°C, 67% relative humidity). The extent of contaminants' bioaccumulation in the larval tissue as well as the effect on growing determinants were examined. The applied heavy metal substrate contamination was shown to impair larval growing indicated by significantly lower post-trial larval mass and feed conversion ratio (FCR). Cd and Pb accumulation factors of 9 and 2, respectively, were determined, while the concentrations of other heavy metals in the larvae remained below the initial substrate concentration. In contrast, mycotoxins and pesticides have neither been accumulated in the larval tissue nor significantly affected the growing determinants in comparison with the control. The use of BSFL as livestock feed requires contaminant monitoring - especially for Cd and Pb - in the substrates as well as in feedstuff containing BSFL to ensure feed and food safety along the value chain.

  10. Buffers and vegetative filter strips

    Science.gov (United States)

    Matthew J. Helmers; Thomas M. Isenhart; Michael G. Dosskey; Seth M. Dabney

    2008-01-01

    This chapter describes the use of buffers and vegetative filter strips relative to water quality. In particular, we primarily discuss the herbaceous components of the following NRCS Conservation Practice Standards.

  11. Direct cooled power electronics substrate

    Science.gov (United States)

    Wiles, Randy H [Powell, TN; Wereszczak, Andrew A [Oak Ridge, TN; Ayers, Curtis W [Kingston, TN; Lowe, Kirk T [Knoxville, TN

    2010-09-14

    The disclosure describes directly cooling a three-dimensional, direct metallization (DM) layer in a power electronics device. To enable sufficient cooling, coolant flow channels are formed within the ceramic substrate. The direct metallization layer (typically copper) may be bonded to the ceramic substrate, and semiconductor chips (such as IGBT and diodes) may be soldered or sintered onto the direct metallization layer to form a power electronics module. Multiple modules may be attached to cooling headers that provide in-flow and out-flow of coolant through the channels in the ceramic substrate. The modules and cooling header assembly are preferably sized to fit inside the core of a toroidal shaped capacitor.

  12. Programmable pH buffers

    Science.gov (United States)

    Gough, Dara Van; Huber, Dale L.; Bunker, Bruce C.; Roberts, Mark E.

    2017-01-24

    A programmable pH buffer comprises a copolymer that changes pK.sub.a at a lower critical solution temperature (LCST) in water. The copolymer comprises a thermally programmable polymer that undergoes a hydrophobic-to-hydrophilic phase change at the LCST and an electrolytic polymer that exhibits acid-base properties that are responsive to the phase change. The programmable pH buffer can be used to sequester CO.sub.2 into water.

  13. Effect of metal complexation on the bioavailability of nitrilotriacetic acid to Chelatobacter heintzii ATCC 29600.

    Science.gov (United States)

    White, V E; Knowles, C J

    2000-01-01

    Many polluted sites contain a mixture of organics and heavy metals. Nitrilotriacetic acid has been chosen as a model organic compound to study the effect of metal binding on organic bioavailability and degradation of organics. The effect of varying the ratio of metal to nitrilotriacetic acid on its utilisation has been examined using the gram-negative bacterium Chelatobacter heintzii ATCC 29600. The following parameters of substrate utilisation were examined: growth, degradation, respiration, mineralisation and nitrilotriacetic acid uptake. Complexation of nitrilotriacetic acid by Cu(II), Ni(II), Co(II) and Zn(II) prevented utilisation of nitrilotriacetic acid by C. heintzii; complexation to Fe(III) or Mn(II) did not. The pattern of inhibition was consistent with a 1:1 stoichiometry of metal binding to nitrilotriacetic acid. Inhibition was not due to metal ion toxicity, but was a result of metal-nitrilotriacetic acid complexes being recalcitrant to degradation. In addition, the effect of complexing (phosphate) and non-complexing (PIPES) buffers on bioavailability was examined: Co and Zn prevented degradation of nitrilotriacetic acid in PIPES buffer, but not in phosphate buffer. This was due to the removal of Co and Zn from solution by phosphate precipitation, leaving nitrilotriacetic acid uncomplexed. The results demonstrated that metal-organic complexation can alter the bioavailability of organic pollutants and may also modulate the toxicity of heavy metals.

  14. Buffer gas acquisition and storage

    Science.gov (United States)

    Parrish, Clyde F.; Lueck, Dale E.; Jennings, Paul A.

    2001-02-01

    The acquisition and storage of buffer gases (primarily argon and nitrogen) from the Mars atmosphere provides a valuable resource for blanketing and pressurizing fuel tanks and as a buffer gas for breathing air for manned missions. During the acquisition of carbon dioxide (CO2), whether by sorption bed or cryo-freezer, the accompanying buffer gases build up in the carbon dioxide acquisition system, reduce the flow of CO2 to the bed, and lower system efficiency. It is this build up of buffer gases that provide a convenient source, which must be removed, for efficient capture of CO2. Removal of this buffer gas barrier greatly improves the charging rate of the CO2 acquisition bed and, thereby, maintains the fuel production rates required for a successful mission. Consequently, the acquisition, purification, and storage of these buffer gases are important goals of ISRU plans. Purity of the buffer gases is a concern e.g., if the CO2 freezer operates at 140 K, the composition of the inert gas would be approximately 21 percent CO2, 50 percent nitrogen, and 29 percent argon. Although there are several approaches that could be used, this effort focused on a hollow-fiber membrane (HFM) separation method. This study measured the permeation rates of CO2, nitrogen (N2), and argon (Ar) through a multiple-membrane system and the individual membranes from room temperature to 193 K and 10 kPa to 300 kPa. Concentrations were measured with a gas chromatograph. The end result was data necessary to design a system that could separate CO2, N2, and Ar. .

  15. Buffer Gas Acquisition and Storage

    Science.gov (United States)

    Parrish, Clyde F.; Lueck, Dale E.; Jennings, Paul A.; Callahan, Richard A.; Delgado, H. (Technical Monitor)

    2001-01-01

    The acquisition and storage of buffer gases (primarily argon and nitrogen) from the Mars atmosphere provides a valuable resource for blanketing and pressurizing fuel tanks and as a buffer gas for breathing air for manned missions. During the acquisition of carbon dioxide (CO2), whether by sorption bed or cryo-freezer, the accompanying buffer gases build up in the carbon dioxide acquisition system, reduce the flow of CO2 to the bed, and lower system efficiency. It is this build up of buffer gases that provide a convenient source, which must be removed, for efficient capture Of CO2 Removal of this buffer gas barrier greatly improves the charging rate of the CO2 acquisition bed and, thereby, maintains the fuel production rates required for a successful mission. Consequently, the acquisition, purification, and storage of these buffer gases are important goals of ISRU plans. Purity of the buffer gases is a concern e.g., if the CO, freezer operates at 140 K, the composition of the inert gas would be approximately 21 percent CO2, 50 percent nitrogen, and 29 percent argon. Although there are several approaches that could be used, this effort focused on a hollow-fiber membrane (HFM) separation method. This study measured the permeation rates of CO2, nitrogen (ND, and argon (Ar) through a multiple-membrane system and the individual membranes from room temperature to 193K and 10 kpa to 300 kPa. Concentrations were measured with a gas chromatograph that used a thermoconductivity (TCD) detector with helium (He) as the carrier gas. The general trend as the temperature was lowered was for the membranes to become more selective, In addition, the relative permeation rates between the three gases changed with temperature. The end result was to provide design parameters that could be used to separate CO2 from N2 and Ar.

  16. Ligating Dopamine as Signal Trigger onto the Substrate via Metal-Catalyst-Free Click Chemistry for "Signal-On" Photoelectrochemical Sensing of Ultralow MicroRNA Levels.

    Science.gov (United States)

    Ye, Cui; Wang, Min Qiang; Gao, Zhong Feng; Zhang, Ying; Lei, Jing Lei; Luo, Hong Qun; Li, Nian Bing

    2016-12-06

    The efficiency of photon-to-electron conversion is extremely restricted by the electron-hole recombinant. Here, a new photoelectrochemical (PEC) sensing platform has been established based on the signal amplification of click chemistry (CC) via hybridization chain reaction (HCR) for highly sensitive microRNA (miRNA) assay. In this proposal, a preferred electron donor dopamine (DA) was first assembled with designed ligation probe (probe-N 3 ) via amidation reaction to achieve DA-coordinated signal probe (P DA -N 3 ). The P DA -N 3 served as a flexible trigger to signal amplification through efficiently suppressing the electron-hole recombinant. Specifically, the P DA -N 3 can be successfully ligated into the trapped hairpins (H1 and H2) via the superior ligation method of metal-catalyst-free CC, in which the electron donor DA was introduced into the assay system. Moreover, the enzyme-free HCR, employed as a versatile amplification way, ensures that lots of P DA -N 3 can be attached to the substrate. This PEC sensing for miRNA-141 detection illustrated the outstanding linear response to a concentration variation from 0.1 fM to 0.5 nM and a detection limit down to 27 aM, without additional electron donors. The sensor is further employed to monitor miRNA-141 from prostate carcinoma cell (22Rv1), showing good quantitative detection capability. This strategy exquisitely influences the analytical performance and offers a new PEC route to highly selective and sensitive detection of biological molecules.

  17. SERS substrate and a method of providing a SERS substrate

    DEFF Research Database (Denmark)

    2011-01-01

    Source: US2011116089A A substrate primarily for SERS determination, the substrate has a number of elongate elements with a density of at least 1x108 elongate elements per cm2 and having metal coated tips. When the elements may be made to lean toward each other, such as by providing a drop...

  18. Thermophysical tests of buffer materials

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, H. [ITC, Tokyo (Japan); Taniguchi, Wataru

    1999-03-01

    Thermodynamic properties of buffer materials were measured for putting in order thermodynamic constants to be used in the near-field thermal analysis. The thermal diffusivity and thermal conductivity were measured as functions of the water content and temperature to deduce the specific heat. The thermal conductivity and specific heat varied significantly as the water content changed. Obtained values of the specific heat agreed well the expected values calculated based on the constituents of the buffer material. Temperature dependence of the thermodynamic constants was found small below 90degC. From the findings, the thermal conductivity and specific heat of the buffer material were formulated as functions of the water content. Thermodynamic study of powdery bentonite was carried out as well with a purpose of use for filling apertures in the artificial barrier. (H. Baba)

  19. Buffer$--An Economic Analysis Tool

    Science.gov (United States)

    Gary Bentrup

    2007-01-01

    Buffer$ is an economic spreadsheet tool for analyzing the cost-benefits of conservation buffers by resource professionals. Conservation buffers are linear strips of vegetation managed for multiple landowner and societal objectives. The Microsoft Excel based spreadsheet can calculate potential income derived from a buffer, including income from cost-share/incentive...

  20. ACETIC ACID AND A BUFFER

    DEFF Research Database (Denmark)

    2009-01-01

    The present invention relates to a composition comprising : a) 0.01-20% wt/wt acetic acid and b) a physiologically tolerable buffer capable of maintaining acetic acid at a pH in the range of 2-7; and use of such a composition as an antimicrobial agent.......The present invention relates to a composition comprising : a) 0.01-20% wt/wt acetic acid and b) a physiologically tolerable buffer capable of maintaining acetic acid at a pH in the range of 2-7; and use of such a composition as an antimicrobial agent....

  1. Chlorobenzene, chloroform, and carbon tetrachloride adsorption on undoped and metal-doped sol-gel substrates (SiO{sub 2}, Ag/SiO{sub 2}, Cu/SiO{sub 2} and Fe/SiO{sub 2})

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, M.A. [Postgrado de Ciencias Ambientales and Departamento de Investigacion en Zeolitas, Instituto de Ciencias, Universidad Autonoma de Puebla, Edificio 76, Complejo de Ciencias, Ciudad Universitaria, CP 72570 Puebla (Mexico)], E-mail: mighern@siu.buap.mx; Gonzalez, A.I.; Corona, L.; Hernandez, F. [Postgrado de Ciencias Ambientales and Departamento de Investigacion en Zeolitas, Instituto de Ciencias, Universidad Autonoma de Puebla, Edificio 76, Complejo de Ciencias, Ciudad Universitaria, CP 72570 Puebla (Mexico); Rojas, F.; Asomoza, M.; Solis, S. [Departamento de Quimica, Universidad Autonoma Metropolitana-Iztapalapa, P.O. Box 55-534, D.F. Mexico (Mexico); Portillo, R.; Salgado, M.A. [Facultad de Ciencias Quimicas, Universidad Autonoma de Puebla (Mexico)

    2009-02-15

    Adsorption isotherms of chlorobenzene, chloroform and carbon tetrachloride vapors on undoped SiO{sub 2}, and metal-doped Ag/SiO{sub 2}, Cu/SiO{sub 2} and Fe/SiO{sub 2} substrates were measured in the temperature range of 398-593 K. These substrates were prepared from a typical sol-gel technique in the presence of metal dopants that rendered an assortment of microporous-mesoporous solids. The relevant characteristic of these materials was the different porosities and micropore to mesopore volume ratios that were displayed; this was due to the effect that the cationic metal valence exerts on the size of the sol-gel globules that compose the porous solid. The texture of these SiO{sub 2} materials was analyzed by X-ray diffraction (XRD), FTIR, and diverse adsorption methods. The pore-size distributions of the adsorbents confirmed the existence of mesopores and supermicropores, while ultramicropores were absent. The Freundlich adsorption model approximately fitted the chlorinated compounds adsorption data on the silica substrates by reason of a heterogeneous energy distribution of adsorption sites. The intensity of the interaction between these organic vapors and the surface of the SiO{sub 2} samples was analyzed through evaluation of the isosteric heat of adsorption and standard adsorption energy; from these last results it was evident that the presence of metal species within the silica structure greatly affected the values of both the amounts adsorbed as well as of the isosteric heats of adsorption.

  2. The effect of respiration buffer composition on mitochondrial metabolism and function.

    Science.gov (United States)

    Wollenman, Lucas C; Vander Ploeg, Matthew R; Miller, Mackinzie L; Zhang, Yizhu; Bazil, Jason N

    2017-01-01

    Functional studies on isolated mitochondria critically rely on the right choice of respiration buffer. Differences in buffer composition can lead to dramatically different respiration rates leading to difficulties in comparing prior studies. The ideal buffer facilities high ADP-stimulated respiratory rates and minimizes substrate transport effects so that the ability to distinguish between various treatments and conditions is maximal. In this study, we analyzed a variety of respiration buffers and substrate combinations to determine the optimal conditions to support mitochondrial function through ADP-stimulated respiration and uncoupled respiration using FCCP. The buffers consisted of a standard KCl based buffer (B1) and three modified buffers with chloride replaced by the K-lactobionate, sucrose, and the antioxidant taurine (B2) or K-gluconate (B3). The fourth buffer (B4) was identical to B2 except that K-lactobionate was replaced with K-gluconate. The substrate combinations consisted of metabolites that utilize different pathways of mitochondrial metabolism. To test mitochondrial function, we used isolated cardiac guinea pig mitochondria and measured oxygen consumption for three respiratory states using an Oroboros Oxygraph-2k. These states were the leak state (energized mitochondria in the absence of adenylates), ADP-stimulated state (energized mitochondria in the presence of saturating ADP concentrations), and uncoupled state (energized mitochondria in the presence of FCCP). On average across all substrate combinations, buffers B2, B3, and B4 had an increase of 16%, 26%, and 35% for the leak state, ADP-simulated state, and uncoupled state, respectively, relative to rates using B1. The common feature distinguishing these buffers from B1 is the notable lack of high chloride concentrations. Based on the respiratory rate metrics obtained with the substrate combinations, we conclude that the adenine nucleotide translocase, the dicarboxylate carrier, and the alpha

  3. High Performance Nano-Constituent Buffer Layer Thin Films to Enable Low Cost Integrated On-the-Move Communications Systems

    National Research Council Canada - National Science Library

    Cole, M. W; Nothwang, W. D; Hubbard, C; Ngo, E; Hirsch, S

    2004-01-01

    .... Utilizing a coplanar device design we successfully designed, fabricated, characterized, and optimized a high performance Ta2O5 thin film passive buffer layer on Si substrates, which will allow...

  4. Preparation of (11n) oriented Bi2Sr2CaCu2O8+x thin films without c-axis twin structure by the metal-organic decomposition method using vicinal SrTiO3 (110) substrates

    Science.gov (United States)

    Yamada, Yasuyuki; Kato, Takahiro; Ishibashi, Takayuki; Okamoto, Tomoichiro; Mori, Natsuki

    2018-01-01

    We have prepared (11n) oriented Bi2Sr2CaCu2O8+x (Bi2212) thin films by metal-organic decomposition method. The vicinal (110) substrate of SrTiO3 (STO) inclined toward the [1 ¯ 10] direction was used for suppressing "c-twinning". In the sample prepared in the O2 atmosphere, only the (11n) peak appeared in the θ-2θ X-ray diffraction pattern. When the miscut angle of the substrate was φ = 10°, it was shown by the scanning electron microscope images and the (008) pole figures that the c-axis was inclined by about 38° and the c-twinning was substantially suppressed. ρab and ρc of this sample were calculated by the corrected van der Pauw method and component calculation of the two-dimensional resistivity tensor. The superconducting transition temperatures were Tc = 81 K. The temperature dependence of ρab was a typical metallic behavior reflecting the characteristics of the ab-plane of Bi2212. On the other hand, that of ρc did not become a typical semiconductor behavior in the c-axis direction of Bi2212, but it showed a metallic behavior. The anisotropic parameter γ was about 10.

  5. Offshore Substrate

    Data.gov (United States)

    California Department of Resources — This shapefile displays the distribution of substrate types from Pt. Arena to Pt. Sal in central/northern California. Originally this data consisted of seven paper...

  6. Study of MgB2 Films on Niobium Substrate

    Science.gov (United States)

    Zhuang, Chenggang; Yao, Dan; Li, Fen; Zhang, Kaicheng; Feng, Qingrong; Gan, Zizhao

    2006-03-01

    We have successfully fabricated polycrystalline MgB2 films on metal niobium by using the hybrid physical-chemical vapor deposition technique. TC (onset) of these samples ranged from 38.5 K to 39.4 K, with δT, 0.1 K ˜ 0.3 K. The observed TC was the highest among all the MgB2 films over metal substrates reported to date. Thicknesses of the films were about 1.0 μm. XRD indicated that lattice constants approached the values of the bulk. The film surface was visible with hexagonal plate-shaped MgB2 crystallites but not dense enough, shown by SEM observation. A line scanning spectra of EDX on the cutting cross section exhibited that there was an oxygen-rich region at the interface. Also, the diffusion of the Mg atoms deeply into the film has resulted in the tenacity and adherence of the film to the substrate. TEM investigation proved the existence of this buffer layer, ˜100 nm. Estimated using magnetic hysteresis loops and Bean model, JC was above 2.30 x 10^4 A/cm^2 at 10 K in zero field. The synthesis of MgB2/Nb films with thickness above one micron, showing certain tenacity, is an important and significant step towards the application of the 2^nd generation MgB2 superconductor wires or tapes.

  7. Role of Buffers in Protein Formulations.

    Science.gov (United States)

    Zbacnik, Teddy J; Holcomb, Ryan E; Katayama, Derrick S; Murphy, Brian M; Payne, Robert W; Coccaro, Richard C; Evans, Gabriel J; Matsuura, James E; Henry, Charles S; Manning, Mark Cornell

    2017-03-01

    Buffers comprise an integral component of protein formulations. Not only do they function to regulate shifts in pH, they also can stabilize proteins by a variety of mechanisms. The ability of buffers to stabilize therapeutic proteins whether in liquid formulations, frozen solutions, or the solid state is highlighted in this review. Addition of buffers can result in increased conformational stability of proteins, whether by ligand binding or by an excluded solute mechanism. In addition, they can alter the colloidal stability of proteins and modulate interfacial damage. Buffers can also lead to destabilization of proteins, and the stability of buffers themselves is presented. Furthermore, the potential safety and toxicity issues of buffers are discussed, with a special emphasis on the influence of buffers on the perceived pain upon injection. Finally, the interaction of buffers with other excipients is examined. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  8. Buffer Zone Requirements for Soil Fumigant Applications

    Science.gov (United States)

    Updated pesticide product labels require fumigant users to establish a buffer zone around treated fields to reduce risks to bystanders. Useful information includes tarp testing guidance and a buffer zone calculator.

  9. 2G HTS wires made on 30 μm thick Hastelloy substrate

    Science.gov (United States)

    Sundaram, A.; Zhang, Y.; Knoll, A. R.; Abraimov, D.; Brownsey, P.; Kasahara, M.; Carota, G. M.; Nakasaki, R.; Cameron, J. B.; Schwab, G.; Hope, L. V.; Schmidt, R. M.; Kuraseko, H.; Fukushima, T.; Hazelton, D. W.

    2016-10-01

    REBCO (RE = rare earth) based high temperature superconducting (HTS) wires are now being utilized for the development of electric and electromagnetic devices for various industrial, scientific and medical applications. In the last several years, the increasing efforts in using the so-called second generation (2G) HTS wires for some of the applications require a further increase in their engineering current density (J e). The applications are those typically related to high magnetic fields where the higher J e of a REBCO wire, in addition to its higher irreversibility fields and higher mechanical strength, is already a major advantage over other superconducting wires. An effective way to increase the J e is to decrease the total thickness of a wire, for which using a thinner substrate becomes an obvious and attractive approach. By using our IBAD-MOCVD (ion beam assisted deposition-metal organic chemical vapor deposition) technology we have successfully made 2G HTS wires using a Hastelloy® C276 substrate that is only 30 μm in thickness. By using this thinner substrate instead of the typical 50 μm thick substrate and with a same critical current (I c), the J e of a wire can be increased by 30% to 45% depending on the copper stabilizer thickness. In this paper, we report the fabrication and characterization of the 2G HTS wires made on the 30 μm thick Hastelloy® C276 substrate. It was shown that with the optimization in the processing protocol, the surface of the thinner Hastelloy® C276 substrate can be readily electropolished to the quality needed for the deposition of the buffer stack. Same in the architecture as that on the standard 50 μm thick substrate, the buffer stack made on the 30 μm thick substrate showed an in-plane texture with a Δϕ of around 6.7° in the LaMnO3 cap layer. Low-temperature in-field transport measurement results suggest that the wires on the thinner substrate had achieved equivalent superconducting performance, most importantly the I

  10. Low-Cost Substrates for High-Performance Nanorod Array LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Sands, Timothy [Purdue University, West Lafayette, IN (United States); Stach, Eric [Purdue University, West Lafayette, IN (United States); Garcia, Edwin [Purdue University, West Lafayette, IN (United States)

    2009-04-30

    The completed project, entitled Low-Cost Substrates for High-Performance Nanorod LEDs, targeted the goal of a phosphor-free nanorod-based white LED with IQE > 50% across the spectrum from 450 nm to 600 nm on metallized silicon substrates. The principal achievements of this project included: Demonstration of (In,Ga)N nanopyramid heterostructures by a conventional OMVPE process. Verification of complete filtering of threading dislocations to yield dislocation-free pyramidal heterostructures. Demonstration of electroluminescence with a peak wavelength of ~600 nm from an (In,Ga)N nanopyramid array LED. Development of a reflective ZrN/AlN buffer layer for epitaxial growth of GaN films and GaN nanopyramid arrays on (111)Si.

  11. Covalent functionalization of carbon nanotube forests grown in situ on a metal-silicon chip

    KAUST Repository

    Johansson, Johan R.

    2012-03-12

    We report on the successful covalent functionalization of carbon nanotube (CNT) forests, in situ grown on a silicon chip with thin metal contact film as the buffer layer between the CNT forests and the substrate. The CNT forests were successfully functionalized with active amine and azide groups, which can be used for further chemical reactions. The morphology of the CNT forests was maintained after the functionalization. We thus provide a promising foundation for a miniaturized biosensor arrays system that can be easily integrated with Complementary Metal-Oxide Semiconductor (CMOS) technology.

  12. Comparative analysis of CRT Buffer, GC saliva check buffer tests and laboratory titration to evaluate saliva buffering capacity.

    Science.gov (United States)

    Maldupa, Ilze; Brinkmane, Anda; Mihailova, Anna

    2011-01-01

    OBJECTIVE. The purpose of this study is to evaluate the ability of two commercial strip tests and laboratory titration to detect saliva buffer capacity. MATERIALS AND METHODS. Sixty-four patients were examined. Stimulated saliva was collected and buffer capacity was determined with two different chair-side strip tests in addition to immediate transportation to the laboratory to check the buffering ability by titrating with 0.005 M HCl and measuring pH by digital pH/Ion meter, used as a gold standart. The correlation were analyzed using the Spearman Rank Correlation Test, Cohen's Kappa coefficient and Pearson's Correlation test, p buffer capacity was found in 23.4% of cases, medium in 62.5%, and low in 14.1%. The Spearman Rank Correlation coefficient between the titration method and CRT Buffer test was 0.685 and the GC Saliva Check Buffer was 0.837. The Kappa coefficient for the CRT Buffer test was 0.508, while the coefficient for the GC Saliva Check Buffer was 0.752. The Pearson Correlation for the GC Saliva Check was 0.675. The difference is found in the buffer capacity at initial pH and at pH value 3. CONCLUSIONS. Both colorimetric tests correlate with the acid titration method in laboratory and are usable for saliva buffer capacity detection in dental offices. Buffer capacity detected in laboratory at different pH values can provide more information regarding caries risk.

  13. Metallic nanomesh

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Zhifeng; Sun, Tianyi; Guo, Chuanfei

    2018-02-20

    A transparent flexible nanomesh having at least one conductive element and sheet resistance less than 300.OMEGA./.quadrature. when stretched to a strain of 200% in at least one direction. The nanomesh is formed by depositing a sacrificial film, depositing, etching, and oxidizing a first metal layer on the film, etching the sacrificial film, depositing a second metal layer, and removing the first metal layer to form a nanomesh on the substrate.

  14. Influence of metal-support interaction on the surface structure of gold nanoclusters deposited on native SiO(x)/Si substrates

    NARCIS (Netherlands)

    Portale, Giuseppe; Sciortino, Luisa; Albonetti, Cristiano; Giannici, Francesco; Martorana, Antonino; Bras, Wim; Biscarini, Fabio; Longo, Alessandro

    2014-01-01

    The structure of small gold nanoclusters (around 2.5 nm) deposited on different silica-on-silicon (SiOx/Si) substrates is investigated using several characterization techniques (AFM, XRD, EXAFS and GISAXS). The grain morphology and the surface roughness of the deposited gold cluster layers are

  15. Improving Water Quality With Conservation Buffers

    Science.gov (United States)

    Lowrance, R.; Dabney, S.; Schultz, R.

    2003-12-01

    Conservation buffer technologies are new approaches that need wider application. In-field buffer practices work best when used in combination with other buffer types and other conservation practices. Vegetative barriers may be used in combination with edge-of-field buffers to protect and improve their function and longevity by dispersing runoff and encouraging sediment deposition upslope of the buffer. It's important to understand how buffers can be managed to help reduce nutrient transport potential for high loading of nutrients from manure land application sites, A restored riparian wetland buffer retained or removed at least 59 percent of the nitrogen and 66 percent of the phosphorus that entered from an adjacent manure land application site. The Bear Creek National Restoration Demonstration Watershed project in Iowa has been the site of riparian forest buffers and filter strips creation; constructed wetlands to capture tile flow; stream-bank bioengineering; in-stream structures; and controlling livestock grazing. We need field studies that test various widths of buffers of different plant community compositions for their efficacy in trapping surface runoff, reducing nonpoint source pollutants in subsurface waters, and enhancing the aquatic ecosystem. Research is needed to evaluate the impact of different riparian grazing strategies on channel morphology, water quality, and the fate of livestock-associated pathogens and antibiotics. Integrating riparian buffers and other conservation buffers into these models is a key objective in future model development.

  16. Buffer capacity of humic acid: thermodynamic approach.

    Science.gov (United States)

    Pertusatti, Jonas; Prado, Alexandre G S

    2007-10-15

    Commercial humic acid was dialyzed and characterized by infrared, UV/vis spectroscopy, (13)C NMR spectrometry, thermogravimetry, and elemental analysis. The dialyzed humic acid was titrated with HNO(3) and NaOH in order to obtain the buffer capacity value (beta). The humic acid presented buffer behavior by base and acid addition, and moreover, an excellent buffer capacity by addition of NaOH. Humic acid showed buffer action between pH 5.5 and 8.0, and a maximum buffer capacity at pH 6.0. The same study was followed calorimetrically to determinate the enthalpy of interaction between H(+)/OH(-) and buffer, which resulted in a maximum enthalpy of -38.49 kJ mol(-1) at pH 6.0. This value suggests that the buffer activity is based on chemisorption of proton and hydroxyl.

  17. Improved textured La{sub 2}Zr{sub 2}O{sub 7} buffer on La{sub 3}TaO{sub 7} seed for all-MOD Buffer/YBCO coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Parans Paranthaman, M. [Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6100 (United States)], E-mail: paranthamanm@ornl.gov; Bhuiyan, M.S.; Sathyamurthy, S. [Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6100 (United States); Heatherly, L.; Cantoni, C.; Goyal, A. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6116 (United States)

    2008-09-15

    The overall purpose of this research is to develop a potentially low-cost, high throughput, high yield, manufacturing process for buffer deposition, and to gain a fundamental understanding of buffer layers required for an all metal-organic deposition (MOD) based chemical solution approach. This understanding is critical to the development of a reliable, robust, low-cost, long-length manufacturing process of 2G wires. The standard RABiTS architectures consists of a starting template of biaxially textured Ni-W (5 at.%) substrate with a seed layer of Y{sub 2}O{sub 3}, a barrier layer of YSZ, and a CeO{sub 2} cap. In this three-layer architecture, all the buffers are deposited using reactive sputtering. We have recently demonstrated that the barrier properties and the performance of MOD La{sub 2}Zr{sub 2}O{sub 7} (LZO) match that of sputtered YSZ layers. In this work, the texture of MOD LZO was also improved by inserting a sputtered Y{sub 2}O{sub 3} seed layer on which LZO grows without any degradation of texture. Significant improvement in the texture of sputtered Y{sub 2}O{sub 3} seeds on NiW substrates is usually observed which is then transferred to the LZO layer. A key challenge for an all-solution approach is to replace the sputtered seed layer with a possible MOD seed layer with improved texture and on which no degradation of LZO texture occurs. Very recently, we have grown MOD La{sub 3}TaO{sub 7} (LTO) seeds directly on biaxially textured Ni-W (3 at.%) with improved texture. In this study, we report a systematic investigation of the growth MOD LZO barrier layer on MOD LTO seeds. Preliminary results show that it is possible to grow MOD LZO with improved texture on MOD LTO seeds. This approach could be potentially used for future all MOD buffer/YBCO coated conductors.

  18. Biaxially strained extremely-thin body In0.53Ga0.47As-on-insulator metal-oxide-semiconductor field-effect transistors on Si substrate and physical understanding on their electron mobility

    Science.gov (United States)

    Kim, SangHyeon; Yokoyama, Masafumi; Nakane, Ryosho; Ichikawa, Osamu; Osada, Takenori; Hata, Masahiko; Takenaka, Mitsuru; Takagi, Shinichi

    2013-10-01

    We report the electrical characteristics of strained In0.53Ga0.47As-on-insulator (-OI) metal-oxide-semiconductor field-effect-transistors (MOSFETs) on Si substrates fabricated by a direct wafer bonding (DWB) technique. 1.7% highly strained In0.53Ga0.47As-OI structures are fabricated on Si substrate by DWB. Strained In0.53Ga0.47As-OI MOSFETs with Ni-InGaAs metal source/drain (S/D) have been operated with high on-current (Ion)/off-current (Ioff) ratio of ˜105 and good current saturation in output characteristics. MOSFETs with 1.7% tensile strain exhibits 1.65 × effective mobility (μeff) enhancement against In0.53Ga0.47As MOSFET without strain. We found that this μeff enhancement is attributed to the increase in mobile free electron concentration under tensile strain, which leads to the lowering in the conduction band minimum (CBM) and the increase in the energy difference between CBM and the Fermi level pinning position due to a large amount of interface states by Hall measurements.

  19. A THEORETICAL DISCUSSION OF THE ECONOMIC EFFECTS OF BUFFER STOCKS AND BUFFER FUNDS

    OpenAIRE

    Simmons, Phil

    1988-01-01

    It has been established that the absence of risk markets justifies market intervention in principle. The form of intervention that has been discussed most widely in the literature is the buffer stock. This paper points out that other forms of intervention, specifically buffer funds, are likely to perform better. The analysis shows that buffer funds are likely to outperform buffer stocks because they address market failure more directly. A sub-theme developed in this paper is that since buffer...

  20. Effect of an Ag buffer layer on a Cu/Ag/Si system

    Energy Technology Data Exchange (ETDEWEB)

    Yukawa, M.; Kitagawa, H.; Iida, S

    2004-10-15

    It is well known that Cu reacts with Si to form copper silicide, even at room temperature. To prevent copper silicide from forming on an Si substrate when Cu is used for wiring or as electrodes, it is necessary to place a buffer layer between Cu and the Si substrate. Silver works as a buffer layer between Cu and the Si substrate to form a layered Cu/Ag/Si structure. In the present paper, we determine the minimum effective Ag buffer layer thickness to prevent Cu diffusing into the Si substrate. The results show that Cu can reach the Si substrate through a 5 nm thick Ag film, but that a 50 nm film prevents Cu from diffusing through to the Si substrate. Using scanning electron microscopy (SEM) to observe the interface layer, it was found that round Ag islands form on the Si substrate, whereas Cu appears as a few large square islands and a lot of small clusters. The small Cu clusters tended to wedge into the gaps between the Ag islands. Furthermore, the results indicate that Cu and Ag repel each other.

  1. Synthetic tunable amplifying buffer circuit in E. coli.

    Science.gov (United States)

    Nilgiriwala, Kayzad Soli; Jiménez, José; Rivera, Phillip Michael; Del Vecchio, Domitilla

    2015-05-15

    While predictable design of a genetic circuit's output is a major goal of synthetic biology, it remains a significant challenge because DNA binding sites in the cell affect the concentration of available transcription factors (TF). To mitigate this problem, we propose to use a TF that results from the (reversible) phosphorylation of protein substrate as a circuit's output. We demonstrate that by comparatively increasing the amounts of substrate and phosphatase, the TF concentration becomes robust to the presence of DNA binding sites and can be kept at a desired value. The circuit's input/output gain can, in turn, be tuned by changing the relative amounts of the substrate and phosphatase, realizing an amplifying buffer circuit with tunable gain. In our experiments in E. coli, we employ phospho-NRI as the output TF, phosphorylated by the NRII kinase, and dephosphorylated by the NRII phosphatase. Amplifying buffer circuits such as ours could be used to insulate a circuit's output from the context, bringing synthetic biology one step closer to modular design.

  2. Enhancement of thermal performance in KRS buffer

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jong Won; Lee, Jong Youl; Kim, Geon Young; Lee, Yang; Koo, J. E

    2007-03-15

    The Korean Reference disposal System consists of the engineered barrier and natural barrier. The main components of the engineered barrier are the canister and buffer. KAERI has developed the buffer for the repository. So far Korean domestic Ca-bentonite was selected as buffer material and the properties of it were characterized. In this report the design requirements of the buffer are fixed based on the characteristics of Korean Ca-bentonite, and the conceptual design of the buffer for KRS is carried out by determining the thickness and shape of the buffer. The thickness of 0.5 m buffer is determined from the mass transfer equation, which gives the less radionuclide release rates from the borehole to the rock. The shape of the buffer is disk and ring. The dry density is 1.6 g/cm{sup 3}. The thickness of the buffer above the canister is 2.5 m and the that of the buffer below the canister is 0.5 m. The disposal system should meet the requirement that the maximum temperature at the interface between the buffer and the canister keeps below 100 .deg.. A 3-dimensional finite element program is used for the thermal analysis around the buffer. The results shows that the current conceptual design of the buffer meets the requirement. Another major role of the buffer is to protect the canister and the spent fuels from the exterior impact. The rock movement around the buffer is introduced to assess the buffer performance. Two cases of rock movement are assessed, and the results show that the buffer mitigates sufficiently the impact from the 10 cm movement of rock. Finally, the resaturation time is estimated through mathematical modeling. ABAQUS program is used for the analysis, and the resaturation time is estimated to be around 10 to 30 years. The enhancement of thermal performance of the disposal system is directly related to the economics of the HLW disposal. The way to enhance the thermal performance is suggested from the results of experiment and design. The thermal

  3. Transmission electron microscopy studies of regrown GaN Ohmic contacts on patterned substrates for metal oxide semiconductor field effect transistor applications

    Science.gov (United States)

    Saripalli, Y. N.; Pei, L.; Biggerstaff, T.; Ramachandran, S.; Duscher, G. J.; Johnson, M. A. L.; Zeng, C.; Dandu, K.; Jin, Y.; Barlage, D. W.

    2007-05-01

    Contact selected area regrowth of GaN was performed by metal organic chemical vapor deposition using a silicon nitride dielectric hard mask to define plasma etched recesses and to define source-drain regions. A low temperature regrowth process at 750-850°C was adopted to limit lateral overgrowth. High resolution electron microscopy images and selected area diffraction confirmed the regrowth selectivity and revealed that the low temperature regrown GaN is epitaxial and has a wurtzite crystal structure. I-V characteristics of the fabricated metal oxidesemiconductor field effect transistor show enhancement mode operation.

  4. MOCVD Grown InP and Related Thin Films on Silicon Substrates for Electron and Photonic Devices Applications

    Science.gov (United States)

    Zhong, Zhenyu

    Heterogeneous integration of III-V compound semiconductor with silicon is attracting renewed attention in recent years due to its potential in electronic and photonic applications. For electronic applications, a robust integration allows low-voltage and high-speed III-V based transistors to couple with mature silicon-based technologies for functional circuit blocks. Several successful demonstrations have been achieved by molecular beam epitaxy (MBE). In regard to photonic applications, silicon photonics is an important area of research with its possible replacement of copper interconnects. The well-developed III-V photonic devices can be utilized on a silicon platform if a seamless integration can be realized. This concept has been extensively demonstrated by wafer bonding, whereas the manufacturing complexity, reliability and yield are main challenges in this transfer technique. In this thesis, demonstration of heterogeneous integration of III-V based electron and photonic devices on silicon substrates is described, using Metal organic chemical vapor deposition (MOCVD), which is considered more compatible with CMOS processes with good potential for wafer level manufacturing. In this work, InP thin films with smooth surface morphology were firstly achieved by introducing thin GaAs buffer layers. The GaAs buffer was optimized based on the surface morphology, crystalline quality and in situ RAS signal. The total thickness of the buffer layer was finally reduced to 1.2mum by trimming the GaAs buffers as a thin buffer is more desirable for process integration. On top of the thin InP buffer layers, high performance metamorphic high electron mobility transistors (mHEMTs) have been demonstrated for the first time. To implement photonic devices on the buffers, the epitaxial films quality was further improved utilizing novel post-treatment techniques, including thermal process and strained layers for defects reduction. InGaAs p-i-n photodetectors lattice-matched to In

  5. Probing the effect of charge transfer enhancement in off resonance mode SERS via conjugation of the probe dye between silver nanoparticles and metal substrates.

    Science.gov (United States)

    Selvakannan, Pr; Ramanathan, Rajesh; Plowman, Blake J; Sabri, Ylias M; Daima, Hemant K; O'Mullane, Anthony P; Bansal, Vipul; Bhargava, Suresh K

    2013-08-21

    The charge transfer-mediated surface enhanced Raman scattering (SERS) of crystal violet (CV) molecules that were chemically conjugated between partially polarized silver nanoparticles and optically smooth gold and silver substrates has been studied under off-resonant conditions. Tyrosine molecules were used as a reducing agent to convert silver ions into silver nanoparticles where oxidised tyrosine caps the silver nanoparticle surface with its semiquinone group. This binding through the quinone group facilitates charge transfer and results in partially oxidised silver. This establishes a chemical link between the silver nanoparticles and the CV molecules, where the positively charged central carbon of CV molecules can bind to the terminal carboxylate anion of the oxidised tyrosine molecules. After drop casting Ag nanoparticles bound with CV molecules it was found that the free terminal amine groups tend to bind with the underlying substrates. Significantly, only those CV molecules that were chemically conjugated between the partially polarised silver nanoparticles and the underlying gold or silver substrates were found to show SERS under off-resonant conditions. The importance of partial charge transfer at the nanoparticle/capping agent interface and the resultant conjugation of CV molecules to off resonant SERS effects was confirmed by using gold nanoparticles prepared in a similar manner. In this case the capping agent binds to the nanoparticle through the amine group which does not facilitate charge transfer from the gold nanoparticle and under these conditions SERS enhancement in the sandwich configuration was not observed.

  6. Silicon—a new substrate for GaN growth

    Indian Academy of Sciences (India)

    Unknown

    obtained good results. Therefore, the use of compliant substrates for GaN growth seems to be promising, as the quality of material is comparable to that grown on SiC or sapphire. (IV) Patterning substrates by masking or etching the sub- strates or buffer layer is another low cost but highly effec- tive way to reduce the stress ...

  7. Carbon thin films deposited by the magnetron sputtering technique using cobalt, copper and nickel as buffer-layers; Filmes finos de carbono depositados por meio da tecnica de magnetron sputtering usando cobalto, cobre e niquel como buffer-layers

    Energy Technology Data Exchange (ETDEWEB)

    Costa e Silva, Danilo Lopes

    2015-11-01

    In this work, carbon thin films were produced by the magnetron sputtering technique using single crystal substrates of alumina c-plane (0001) and Si (111) and Si (100) substrates, employing Co, Ni and Cu as intermediate films (buffer-layers). The depositions were conducted in three stages, first with cobalt buffer-layers where only after the production of a large number of samples, the depositions using cooper buffer-layers were carried out on Si substrates. Then, depositions were performed with nickel buffer layers using single-crystal alumina substrates. The crystallinity of the carbon films was evaluated by using the technique of Raman spectroscopy and, then, by X-ray diffraction (XRD). The morphological characterization of the films was performed by scanning electron microscopy (SEM and FEG-SEM) and high-resolution transmission electron microscopy (HRTEM). The XRD peaks related to the carbon films were observed only in the results of the samples with cobalt and nickel buffer-layers. The Raman spectroscopy showed that the carbon films with the best degree of crystallinity were the ones produced with Si (111) substrates, for the Cu buffers, and sapphire substrates for the Ni and Co buffers, where the latter resulted in a sample with the best crystallinity of all the ones produced in this work. It was observed that the cobalt has low recovering over the alumina substrates when compared to the nickel. Sorption tests of Ce ions by the carbon films were conducted in two samples and it was observed that the sorption did not occur probably because of the low crystallinity of the carbon films in both samples. (author)

  8. Melatonin: Buffering the Immune System

    Science.gov (United States)

    Carrillo-Vico, Antonio; Lardone, Patricia J.; Álvarez-Sánchez, Nuria; Rodríguez-Rodríguez, Ana; Guerrero, Juan M.

    2013-01-01

    Melatonin modulates a wide range of physiological functions with pleiotropic effects on the immune system. Despite the large number of reports implicating melatonin as an immunomodulatory compound, it still remains unclear how melatonin regulates immunity. While some authors argue that melatonin is an immunostimulant, many studies have also described anti-inflammatory properties. The data reviewed in this paper support the idea of melatonin as an immune buffer, acting as a stimulant under basal or immunosuppressive conditions or as an anti-inflammatory compound in the presence of exacerbated immune responses, such as acute inflammation. The clinical relevance of the multiple functions of melatonin under different immune conditions, such as infection, autoimmunity, vaccination and immunosenescence, is also reviewed. PMID:23609496

  9. Melatonin: Buffering the Immune System

    Directory of Open Access Journals (Sweden)

    Juan M. Guerrero

    2013-04-01

    Full Text Available Melatonin modulates a wide range of physiological functions with pleiotropic effects on the immune system. Despite the large number of reports implicating melatonin as an immunomodulatory compound, it still remains unclear how melatonin regulates immunity. While some authors argue that melatonin is an immunostimulant, many studies have also described anti-inflammatory properties. The data reviewed in this paper support the idea of melatonin as an immune buffer, acting as a stimulant under basal or immunosuppressive conditions or as an anti-inflammatory compound in the presence of exacerbated immune responses, such as acute inflammation. The clinical relevance of the multiple functions of melatonin under different immune conditions, such as infection, autoimmunity, vaccination and immunosenescence, is also reviewed.

  10. MOVPE growth of GaN on 6-inch SOI-substrates: effect of substrate parameters on layer quality and strain

    Science.gov (United States)

    Lemettinen, J.; Kauppinen, C.; Rudzinski, M.; Haapalinna, A.; Tuomi, T. O.; Suihkonen, S.

    2017-04-01

    We demonstrate that higher crystalline quality, lower strain and improved electrical characteristics can be achieved in gallium nitride (GaN) epitaxy by using a silicon-on-insulator (SOI) substrate compared to a bulk silicon (Si) substrate. GaN layers were grown by metal-organic vapor phase epitaxy on 6-inch bulk Si and SOI wafers using the standard step graded AlGaN and AlN approach. The GaN layers grown on SOI exhibited lower strain according to x-ray diffraction analysis. Defect selective etching measurements suggested that the use of SOI substrate for GaN epitaxy reduces the dislocation density approximately by a factor of two. Furthermore, growth on SOI substrate allows one to use a significantly thinner AlGaN buffer compared to bulk Si. Synchrotron radiation x-ray topography analysis confirmed that the stress relief mechanism in GaN on SOI epitaxy is the formation of a dislocation network to the SOI device Si layer. In addition, the buried oxide layer significantly improves the vertical leakage characteristics as the onset of the breakdown is delayed by approximately 400 V. These results show that the GaN on the SOI platform is promising for power electronics applications.

  11. Systemic Risk, Bank's Capital Buffer, and Leverage

    OpenAIRE

    Wibowo, Buddi

    2017-01-01

    This paper measures individual bank's impact on banking systemic risk and examines the effect of individual bank's capital buffer and leverage to bank's systemic risk impact in Indonesia during 2010-2014. Using Merton's distance-to-default to measure systemic risk, the study shows a significant negative relationship between bank's capital buffer and systemic risk. High capital buffer tends to lowering bank's impact on systemic risk. Bank's leverage level also influences its contribution to sy...

  12. Signature-based store checking buffer

    Science.gov (United States)

    Sridharan, Vilas; Gurumurthi, Sudhanva

    2015-06-02

    A system and method for optimizing redundant output verification, are provided. A hardware-based store fingerprint buffer receives multiple instances of output from multiple instances of computation. The store fingerprint buffer generates a signature from the content included in the multiple instances of output. When a barrier is reached, the store fingerprint buffer uses the signature to verify the content is error-free.

  13. NiTi Intermetallic Surface Coatings by Laser Metal Deposition for Improving Wear Properties of Ti-6Al-4V Substrates

    Directory of Open Access Journals (Sweden)

    Mokgadi Nomsa Mokgalaka

    2014-01-01

    Full Text Available The NiTi intermetallic possesses a number of good properties, such as high wear, oxidation, and corrosion resistance. This paper focuses on the deposition of NiTi intermetallic coatings on Ti6Al4V substrate by laser melting of Ti and Ni elemental powder mixtures. The effect of varying the Ti content in the NiTi composition on the microstructure and wear properties of the coatings was investigated. The microstructure of the NiTi intermetallic coatings were characterized by the scanning electron microscope (SEM equipped with Energy Dispersive Spectroscope (EDS. The wear properties of the coatings were performed under accelerated dry sliding wear tests. The results obtained from the SEM/EDS analysis; show that the coatings consist of Ni and Ti elements from the feedstock, and the NiTi, NiTi2 and NiTi3, intermetallic phases. Dry sliding wear analysis revealed that there is correlation between the hardness and the wear rate. The coatings displayed significant improvement in wear resistance up to 80% compared to the substrate.

  14. Heavy metals in municipal solid waste deposits

    Energy Technology Data Exchange (ETDEWEB)

    Flyhammar, P.

    1997-12-01

    Extensive use of heavy metals in modern society influences routes followed by fluxes on the surface of the Earth. The changed flow paths may be harmful for the balance of biological systems at different levels, micro-organisms, human beings and whole ecosystems, since the toxicity of heavy metals is determined by their concentrations and chemical forms. Despite the low mobility of heavy metals (Zn, Cu, Pb, Cr, Ni and Cd) in municipal landfills, it was found that extensive transformations of the binding forms of heavy metal take place within the waste mass during the degradation of the waste. These changes appear to be closely related to the development of early diagenetic solid phases, i.e. new secondary solid phases formed in the waste. The heavy metals often constitute a minor part of these phases and the bindings include several forms such as adsorption, complexation, coprecipitation, precipitation, etc. It was also found that the associations between heavy metals and solid phases are dominated by several binding forms to one specific substrate rather than bindings to various solid phases. The mobility of iron and manganese seems to increase during the processes involved in waste degradation due to the solution of oxide/hydroxide phases, while the heavy metals appear to become less mobile due to their binding to organic compounds and sulphides. However, one exception in this case may be nickel. Another aspect of the transformation of heavy metals is the accumulation of pools of heavy metals which can become susceptible to environmental changes, such as oxidation or acidification. However, the risk of increased mobilization caused by lower pH values seem to be limited since municipal solid waste has a large buffer capacity. 66 refs, 9 figs, 3 tabs 66 refs, 9 figs, 3 tabs

  15. Temperature buffer test. Dismantling operation

    Energy Technology Data Exchange (ETDEWEB)

    Aakesson, Mattias [Clay Technology AB, Lund (Sweden)

    2010-12-15

    The Temperature Buffer Test (TBT) is a joint project between SKB/ANDRA and supported by ENRESA (modelling) and DBE (instrumentation), which aims at improving the understanding and to model the thermo-hydro-mechanical behavior of buffers made of swelling clay submitted to high temperatures (over 100 deg C) during the water saturation process. The test has been carried out in a KBS-3 deposition hole at Aespoe HRL. It was installed during the spring of 2003. Two heaters (3 m long, 0.6 m diameter) and two buffer arrangements have been investigated: the lower heater was surrounded by bentonite in the usual way, whereas the upper heater was surrounded by a ring of sand. The test was dismantled and sampled during a period from the end of October 2009 to the end of April 2010, and this report describes this operation. Different types of samples have been obtained during this operation. A large number of diameter 50 mm bentonite cores have been taken for analysis of water content and density. Large pieces, so-called big sectors, have been taken for hydro-mechanical and chemical characterizations. Finally, there has been an interest to obtain different types of interface samples in which bentonite were in contact with sand, iron or concrete. One goal has been to investigate the retrievability of the upper heater, given the possibility to remove the surrounding sand shield, and a retrieval test has therefore been performed. The sand in the shield was first removed with an industrial vacuum cleaner after loosening the material through mechanical means (with hammer drill and core machine). A front loader was subsequently used for applying a sufficient lifting force to release the heater from the bentonite underneath. The experiment has been documented in different aspects: measurements of the coordinate (height or radius) of different interfaces (between bentonite blocks and between bentonite and sand); verification of sensor positions and retrieval of sensors for subsequent

  16. Effectiveness of vegetation buffers surrounding playa wetlands at contaminant and sediment amelioration.

    Science.gov (United States)

    Haukos, David A; Johnson, Lacrecia A; Smith, Loren M; McMurry, Scott T

    2016-10-01

    Playa wetlands, the dominant hydrological feature of the semi-arid U.S. High Plains providing critical ecosystem services, are being lost and degraded due to anthropogenic alterations of the short-grass prairie landscape. The primary process contributing to the loss of playas is filling of the wetland through accumulation of soil eroded and transported by precipitation from surrounding cultivated watersheds. We evaluated effectiveness of vegetative buffers surrounding playas in removing metals, nutrients, and dissolved/suspended sediments from precipitation runoff. Storm water runoff was collected at 10-m intervals in three buffer types (native grass, fallow cropland, and Conservation Reserve Program). Buffer type differed in plant composition, but not in maximum percent removal of contaminants. Within the initial 60 m from a cultivated field, vegetation buffers of all types removed >50% of all measured contaminants, including 83% of total suspended solids (TSS) and 58% of total dissolved solids (TDS). Buffers removed an average of 70% of P and 78% of N to reduce nutrients entering the playa. Mean maximum percent removal for metals ranged from 56% of Na to 87% of Cr. Maximum removal was typically at 50 m of buffer width. Measures of TSS were correlated with all measures of metals and nutrients except for N, which was correlated with TDS. Any buffer type with >80% vegetation cover and 30-60 m in width would maximize contaminant removal from precipitation runoff while ensuring that playas would continue to function hydrologically to provide ecosystem services. Watershed management to minimize erosion and creations of vegetation buffers could be economical and effective conservation tools for playa wetlands. Published by Elsevier Ltd.

  17. Al-doped ZnO films deposited on a slightly reduced buffer layer by reactive dc unbalanced magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Kusayanagi, Minehide; Uchida, Azusa; Oka, Nobuto; Jia, Junjun [Graduate School of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara, Kanagawa 252-5258 (Japan); Nakamura, Shin-ichi [Center for Instrumental Analysis, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara, Kanagawa 252-5258 (Japan); Shigesato, Yuzo, E-mail: yuzo@chem.aoyama.ac.jp [Graduate School of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara, Kanagawa 252-5258 (Japan)

    2014-03-31

    Al-doped ZnO (AZO) films were deposited on a fused silica glass substrate by reactive dc unbalanced magnetron sputtering using a Zn–Al (Al: 3.6 at.%) alloy target with an impedance control system. A very thin slightly reduced AZO buffer layer was inserted between the glass substrate and AZO films. For the AZO films deposited at 200 °C, the lowest resistivity in the absence of the buffer layer was 8.0 × 10{sup −4} Ω cm, whereas this was reduced to 5.9 × 10{sup −4} Ω cm after introducing a 5-nm-thick buffer layer. The transmittance for all the films was above 80% in the visible region. The effects of the buffer layer were analysed and discussed in detail. It is found that the insertion of the buffer layer can improve the crystallinity of the AZO film. - Highlights: • Al-doped ZnO (AZO) films with AZO buffer layers were deposited. • Reactive dc unbalance magnetron sputtering with impedance control was used. • Insertion of a buffer layer can lead to a lower resistivity. • Insertion of a buffer layer improved the crystallinity of AZO films.

  18. State of the art and prospective of large scale applications of YBCO thick films grown on metallic substrates; Possibilita` applicative a larga scala dei film spessi di YBCO su substrati metallici: Stato dell`arte e prospettive

    Energy Technology Data Exchange (ETDEWEB)

    Boffa, Vincenzo [ENEA, Centro Ricerche Frascati, Rome (Italy). Dipt. Energia

    1997-09-01

    In the framework of the high temperature superconducting materials, YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO) shows very interesting intrinsic superconducting transport properties at temperature higher than the liquid nitrogen temperature. These properties are very important in large scale applications: transport of energy, magnets, transformers, etc. Unfortunately the potential of this material cannot be achieved today, since it is very difficult to manufacture YBCO based tapes or cables. In the last years several groups have tried to overcome the problems with new fabrication techniques. In the present report the state of the art and the prospective in the field of YBCO film fabrication on metallic substrates are presented.

  19. Carrier tuning the metal-insulator transition of epitaxial La0.67Sr0.33MnO3 thin film on Nb doped SrTiO3 substrate

    Directory of Open Access Journals (Sweden)

    J. M. Zhan

    2016-04-01

    Full Text Available La0.67Sr0.33MnO3 (LSMO thin films were deposited on (001SrTiO3(STO and n-type doped Nb:SrTiO3(NSTO single crystal substrates respectively. The metal to insulator transition temperature(TMI of LSMO film on NSTO is lower than that on STO, and the TMI of LSMO can be tuned by changing the applied current in the LSMO/NSTO p-n junction. Such behaviors were considered to be related to the carrier concentration redistribution in LSMO film caused by the change of depletion layer thickness in p-n junction which depends greatly on the applied electric field. The phenomenon could be used to configure artificial devices and exploring the underlying physics.

  20. Single-photon emission at 1.55 μm from MOVPE-grown InAs quantum dots on InGaAs/GaAs metamorphic buffers

    Science.gov (United States)

    Paul, Matthias; Olbrich, Fabian; Höschele, Jonatan; Schreier, Susanne; Kettler, Jan; Portalupi, Simone Luca; Jetter, Michael; Michler, Peter

    2017-07-01

    By metal-organic vapor-phase epitaxy, we have fabricated InAs quantum dots (QDs) on InGaAs/GaAs metamorphic buffer layers on a GaAs substrate with area densities that allow addressing single quantum dots. The photoluminescence emission from the quantum dots is shifted to the telecom C-band at 1.55 μm with a high yield due to the reduced stress in the quantum dots. The lowered residual strain at the surface of the metamorphic buffer layer results in a reduced lattice mismatch between the quantum dot material and growth surface. The quantum dots exhibit resolution-limited linewidths (mean value: 59 μeV) and low fine-structure splittings. Furthermore, we demonstrate single-photon emission ( g ( 2 ) ( 0 ) = 0.003 ) at 1.55 μm and decay times on the order of 1.4 ns comparable to InAs QDs directly deposited on GaAs substrates. Our results suggest that these quantum dots can not only compete with their counterparts deposited on InP substrates but also constitute an InAs/GaAs-only approach for the development of non-classical light sources in the telecom C-band.

  1. Nanomechanical and Macrotribological Properties of CVD-Grown Graphene as a Middle Layer between Metal Pt Cylinders and SiO2/Si Substrate

    Directory of Open Access Journals (Sweden)

    Hongyan Wu

    2015-01-01

    Full Text Available The CVD-grown graphene as a middle layer was introduced between Pt cylinders and SiO2/Si to extend the application of graphene for improving the wear performance of microelectromechanical systems. Periodic arrays of Pt cylinders were prepared on the graphene/SiO2/Si (Pt/graphene and SiO2/Si substrate (Pt/SiO2 using the magnetron sputtering technique. To characterize Pt/graphene and Pt/SiO2, nanoindentation and macrotribological tests were performed. The results showed that the friction coefficient was lower and the wear lifetime of Pt/graphene was longer than those of Pt/SiO2. Graphene, as a middle layer, was not only observed to have significant influence on the mechanical properties (i.e., microhardness and elastic modulus, but also found to improve the adhesive strength between SiO2/Si and Pt cylinders.

  2. Biosensors based on enzyme field-effect transistors for determination of some substrates and inhibitors.

    Science.gov (United States)

    Dzyadevych, Sergei V; Soldatkin, Alexey P; Korpan, Yaroslav I; Arkhypova, Valentyna N; El'skaya, Anna V; Chovelon, Jean-Marc; Martelet, Claude; Jaffrezic-Renault, Nicole

    2003-10-01

    This paper is a review of the authors' publications concerning the development of biosensors based on enzyme field-effect transistors (ENFETs) for direct substrates or inhibitors analysis. Such biosensors were designed by using immobilised enzymes and ion-selective field-effect transistors (ISFETs). Highly specific, sensitive, simple, fast and cheap determination of different substances renders them as promising tools in medicine, biotechnology, environmental control, agriculture and the food industry. The biosensors based on ENFETs and direct enzyme analysis for determination of concentrations of different substrates (glucose, urea, penicillin, formaldehyde, creatinine, etc.) have been developed and their laboratory prototypes were fabricated. Improvement of the analytical characteristics of such biosensors may be achieved by using a differential mode of measurement, working solutions with different buffer concentrations and specific agents, negatively or positively charged additional membranes, or genetically modified enzymes. These approaches allow one to decrease the effect of the buffer capacity influence on the sensor response in an aim to increase the sensitivity of the biosensors and to extend their dynamic ranges. Biosensors for the determination of concentrations of different toxic substances (organophosphorous pesticides, heavy metal ions, hypochlorite, glycoalkaloids, etc.) were designed on the basis of reversible and/or irreversible enzyme inhibition effect(s). The conception of an enzymatic multibiosensor for the determination of different toxic substances based on the enzyme inhibition effect is also described. We will discuss the respective advantages and disadvantages of biosensors based on the ENFETs developed and also demonstrate their practical application.

  3. 21 CFR 520.1696a - Buffered penicillin powder, penicillin powder with buffered aqueous diluent.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Buffered penicillin powder, penicillin powder with... FORM NEW ANIMAL DRUGS § 520.1696a Buffered penicillin powder, penicillin powder with buffered aqueous diluent. (a) Specifications. When reconstituted, each milliliter contains penicillin G procaine equivalent...

  4. THE BUFFER CAPACITY OF AIRWAY EPITHELIAL SECRETIONS

    Directory of Open Access Journals (Sweden)

    Dusik eKim

    2014-06-01

    Full Text Available The pH of airway epithelial secretions influences bacterial killing and mucus properties and is reduced by acidic pollutants, gastric reflux, and respiratory diseases such as cystic fibrosis (CF. The effect of acute acid loads depends on buffer capacity, however the buffering of airway secretions has not been well characterized. In this work we develop a method for titrating micro-scale (30 µl volumes and use it to study fluid secreted by the human airway epithelial cell line Calu-3, a widely used model for submucosal gland serous cells. Microtitration curves revealed that HCO3- is the major buffer. Peak buffer capacity (β increased from 17 to 28 mM/pH during forskolin stimulation, and was reduced by >50% in fluid secreted by cystic fibrosis transmembrane conductance regulator (CFTR-deficient Calu-3 monolayers, confirming an important role of CFTR in HCO3- secretion. Back-titration with NaOH revealed non-volatile buffer capacity due to proteins synthesized and released by the epithelial cells. Lysozyme and mucin concentrations were too low to buffer Calu-3 fluid significantly, however model titrations of porcine gastric mucins at concentrations near the sol-gel transition suggest that mucins may contribute to the buffer capacity of ASL in vivo. We conclude that CFTR-dependent HCO3- secretion and epithelially-derived proteins are the predominant buffers in Calu-3 secretions.

  5. The buffer capacity of airway epithelial secretions.

    Science.gov (United States)

    Kim, Dusik; Liao, Jie; Hanrahan, John W

    2014-01-01

    The pH of airway epithelial secretions influences bacterial killing and mucus properties and is reduced by acidic pollutants, gastric reflux, and respiratory diseases such as cystic fibrosis (CF). The effect of acute acid loads depends on buffer capacity, however the buffering of airway secretions has not been well characterized. In this work we develop a method for titrating micro-scale (30 μl) volumes and use it to study fluid secreted by the human airway epithelial cell line Calu-3, a widely used model for submucosal gland serous cells. Microtitration curves revealed that HCO(-) 3 is the major buffer. Peak buffer capacity (β) increased from 17 to 28 mM/pH during forskolin stimulation, and was reduced by >50% in fluid secreted by cystic fibrosis transmembrane conductance regulator (CFTR)-deficient Calu-3 monolayers, confirming an important role of CFTR in HCO(-) 3 secretion. Back-titration with NaOH revealed non-volatile buffer capacity due to proteins synthesized and released by the epithelial cells. Lysozyme and mucin concentrations were too low to buffer Calu-3 fluid significantly, however model titrations of porcine gastric mucins at concentrations near the sol-gel transition suggest that mucins may contribute to the buffer capacity of ASL in vivo. We conclude that CFTR-dependent HCO(-) 3 secretion and epithelially-derived proteins are the predominant buffers in Calu-3 secretions.

  6. Buffer Management Simulation in ATM Networks

    Science.gov (United States)

    Yaprak, E.; Xiao, Y.; Chronopoulos, A.; Chow, E.; Anneberg, L.

    1998-01-01

    This paper presents a simulation of a new dynamic buffer allocation management scheme in ATM networks. To achieve this objective, an algorithm that detects congestion and updates the dynamic buffer allocation scheme was developed for the OPNET simulation package via the creation of a new ATM module.

  7. Droop-free AlxGa1-xN/AlyGa1-yN quantum-disks-in-nanowires ultraviolet LED emitting at 337 nm on metal/silicon substrates

    KAUST Repository

    Janjua, Bilal

    2017-01-18

    Currently the AlGaN-based ultraviolet (UV) solid-state lighting research suffers from numerous challenges. In particular, low internal quantum efficiency, low extraction efficiency, inefficient doping, large polarization fields, and high dislocation density epitaxy constitute bottlenecks in realizing high power devices. Despite the clear advantage of quantum-confinement nanostructure, it has not been widely utilized in AlGaN-based nanowires. Here we utilize the self-assembled nanowires (NWs) with embedding quantum-disks (Qdisks) to mitigate these issues, and achieve UV emission of 337 nm at 32 A/cm (80 mA in 0.5 × 0.5 mm device), a turn-on voltage of ∼5.5 V and droop-free behavior up to 120 A/cm of injection current. The device was grown on a titanium-coated n-type silicon substrate, to improve current injection and heat dissipation. A narrow linewidth of 11.7 nm in the electroluminescence spectrum and a strong wavefunctions overlap factor of 42% confirm strong quantum confinement within uniformly formed AlGaN/AlGaN Qdisks, verified using transmission electron microscopy (TEM). The nitride-based UV nanowires light-emitting diodes (NWs-LEDs) grown on low cost and scalable metal/silicon template substrate, offers a scalable, environment friendly and low cost solution for numerous applications, such as solid-state lighting, spectroscopy, medical science and security.

  8. Molecular sensitivity on graphene decorated with noble metal nanoparticles: Graphene-mediated surface-enhanced Raman scattering (G-SERS) substrates

    Science.gov (United States)

    Gupta, Sanju; Banaszak, Alexander; Smith, Tyler

    Raman scattering signal enhancement that uses graphene as support, graphene-enhanced Raman scattering (G-SERS), is a recent phenomenon. While SERS enhancement arises due to electromagnetic mechanism, G-SERS also relies on chemical mechanism and therefore it shows unique molecular sensitivity. In this work, we developed graphene materials decorated with silver and gold nanoparticles for detecting methylene blue (MB) and rhodamine 6G (Rh6G) in view of optical and biological importance. The results illustrate that silver and gold nanoparticles immobilized on multilayer graphene graphene oxide and reduced graphene oxide significantly enhance the signal, and as cascaded amplification of SERS signal on multilayer architecture, larger than those only on metal nanoparticles. The sensitivity can be tuned by controlling the size of nanoparticles and the highest SERS enhancement factor (four orders) is achieved at optimal 30 nm silver and 40 nm gold nanoparticles on reduced graphene oxide and multilayer graphene. They serve as `smart' SERS platforms capable of detecting MB and Rh6G below 10 pM concentration. The enhancement is discussed in 1. molecular structures (molecular symmetry; face-down and edge-on) 2. charge-transfer interaction between molecules and graphene and 3. graphene-metal nanoparticle interfacial hybridization. The signal enhancement is supported by change in UV-vis absorption spectra of molecules in contact with graphene guiding molecular detection and biotechnology. KY NSF EPSCoR.

  9. Optimization of protein buffer cocktails using Thermofluor.

    Science.gov (United States)

    Reinhard, Linda; Mayerhofer, Hubert; Geerlof, Arie; Mueller-Dieckmann, Jochen; Weiss, Manfred S

    2013-02-01

    The stability and homogeneity of a protein sample is strongly influenced by the composition of the buffer that the protein is in. A quick and easy approach to identify a buffer composition which increases the stability and possibly the conformational homogeneity of a protein sample is the fluorescence-based thermal-shift assay (Thermofluor). Here, a novel 96-condition screen for Thermofluor experiments is presented which consists of buffer and additive parts. The buffer screen comprises 23 different buffers and the additive screen includes small-molecule additives such as salts and nucleotide analogues. The utilization of small-molecule components which increase the thermal stability of a protein sample frequently results in a protein preparation of higher quality and quantity and ultimately also increases the chances of the protein crystallizing.

  10. Buffer sizing for multi-hop networks

    KAUST Repository

    Shihada, Basem

    2014-01-28

    A cumulative buffer may be defined for an interference domain in a wireless mesh network and distributed among nodes in the network to maintain or improve capacity utilization of network resources in the interference domain without increasing packet queuing delay times. When an interference domain having communications links sharing resources in a network is identified, a cumulative buffer size is calculated. The cumulative buffer may be distributed among buffers in each node of the interference domain according to a simple division or according to a cost function taking into account a distance of the communications link from the source and destination. The network may be monitored and the cumulative buffer size recalculated and redistributed when the network conditions change.

  11. Metallization of electronic insulators

    Science.gov (United States)

    Gottesfeld, Shimshon; Uribe, Francisco A.

    1994-01-01

    An electroplated element is formed to include an insulating substrate, a conducting polymer polymerized in situ on the substrate, and a metal layer deposited on the conducting polymer. In one application a circuit board is formed by polymerizing pyrrole on an epoxy-fiberglass substrate in a single step process and then electrodepositing a metal over the resulting polypyrrole polymer. No chemical deposition of the metal is required prior to electroplating and the resulting layer of substrate-polymer-metal has excellent adhesion characteristics. The metal deposition is surprisingly smooth and uniform over the relatively high resistance film of polypyrrole. A continuous manufacturing process is obtained by filtering the solution between successive substrates to remove polymer formed in the solution, by maintaining the solution oxidizing potential within selected limits, and by adding a strong oxidant, such as KMnO.sub.4 at periodic intervals to maintain a low sheet resistivity in the resulting conducting polymer film.

  12. Studies on Ba(2)YNbO(6) Buffer Layers for Subsequent YBa(2)Cu(3)O(7-x) Film Growth

    National Research Council Canada - National Science Library

    Sathiraju, Srinivas; Barnes, Paul N; Varanasi, Chakrapani; Wheeler, Robert

    2004-01-01

    In this paper, we are reporting a dielectric oxide buffer Ba(2)YNbO(6) (BYNO) and its performance on various substrates for a potential buffer layer for the growth of YBa(2)Cu(3)O(7-x) (YBCO) coated conductors. Ba(2)YNbO(6...

  13. STM images of a large organic molecule adsorbed on a bare metal substrate or on a thin insulating layer: Visualization of HOMO and LUMO

    Science.gov (United States)

    Villagomez, Carlos Javier; Zambelli, Tomaso; Gauthier, Sébastien; Gourdon, André; Stojkovic, Sladjana; Joachim, Christian

    2009-06-01

    An isomer of the methylterrylene molecule was adsorbed both on Cu(111) and on a NaCl bilayer deposited on Cu(111) and imaged by ultra high vacuum scanning tunneling microscopy at low temperature (5 K). On the bare metal surface, the STM images do not reveal any intramolecular resolution and do not depend on the applied tunnel bias. On the contrary, the images acquired at specific bias voltages for the molecule on the salt layer show a striking similarity with the spatial distribution of the electronic probability density in the highest occupied molecular orbital (HOMO) and in the lowest unoccupied molecular orbital (LUMO) of free methylterrylene. They are well reproduced by elastic scattering quantum chemistry calculations. These data provide a direct view of the hyperconjugative interaction between the methyl group and the frontier orbitals of terrylene.

  14. COMBINATIONS OF BUFFER-STOCKS AND BUFFER-FUNDS FOR WOOL PRICE STABILISATION IN AUSTRALIA

    OpenAIRE

    Moir, Brian; Piggott, Roley R.

    1991-01-01

    In this paper a preliminary analysis is presented of a combined buffer-fund and buffer-stock as an alternative to a pure buffer-fund or a pure buffer stock for stabilising wool prices. The alternatives analysed are designed so that each provides the same prices to producers as did the Reserve Price Scheme over the period of analysis. Least-cost combinations of policy instruments are derived. The results show that there is considerable potential for cost savings to be made by combining buffer-...

  15. Temperature buffer test. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Aakesson, Mattias [Clay Technology AB, Lund (Sweden)

    2012-04-15

    The Temperature Buffer Test (TBT) is a joint project between SKB/ANDRA and supported by ENRESA (modelling) and DBE (instrumentation), which aims at improving the understanding and to model the thermo-hydro-mechanical behavior of buffers made of swelling clay submitted to high temperatures (over 100 deg C) during the water saturation process. The test has been carried out in a KBS-3 deposition hole at Aspo HRL. It was installed during the spring of 2003. Two steel heaters (3 m long, 0.6 m diameter) and two buffer arrangements have been investigated: the lower heater was surrounded by rings of compacted Wyoming bentonite only, whereas the upper heater was surrounded by a composite barrier, with a sand shield between the heater and the bentonite. The test was dismantled and sampled during the winter of 2009/2010. This report is the final report and a summary of all work performed within the TBT project. The design and the installation of the different components are summarized: the depositions hole, the heating system, the bentonite blocks with emphasis on the initial density and water content in these, the filling of slots with sand or pellets, the retaining construction with the plug, lid and nine anchor cables, the artificial saturation system, and finally the instrumentation. An overview of the operational conditions is presented: the power output from heaters, which was 1,500 W (and also 1,600 W) from each heater during the first {approx}1,700 days, and then changed to 1,000 and 2,000 W, for the upper and lower heater respectively, during the last {approx}600 days. From the start, the bentonite was hydrated with a groundwater from a nearby bore-hole, but this groundwater was replaced with de-ionized water from day {approx}1,500, due to the high flow resistance of the injections points in the filter, which implied that a high filter pressure couldn't be sustained. The sand shield around the upper heater was hydrated from day {approx}1,500 to day {approx}1

  16. Electrophoretic mobilities of erythrocytes in various buffers

    Science.gov (United States)

    Plank, L. D.; Kunze, M. E.; Todd, P. W.

    1985-01-01

    The calibration of space flight equipment depends on a source of standard test particles, this test particle of choice is the fixed erythrocyte. Erythrocytes from different species have different electrophoretic mobilities. Electrophoretic mobility depends upon zeta potential, which, in turn depends upon ionic strength. Zeta potential decreases with increasing ionic strength, so cells have high electrophoretic mobility in space electrophoresis buffers than in typical physiological buffers. The electrophoretic mobilities of fixed human, rat, and rabbit erythrocytes in 0.145 M salt and buffers of varying ionic strength, temperature, and composition, to assess the effects of some of the unique combinations used in space buffers were characterized. Several effects were assessed: glycerol or DMSO (dimethylsulfoxide) were considered for use as cryoprotectants. The effect of these substances on erythrocyte electrophoretic mobility was examined. The choice of buffer depended upon cell mobility. Primary experiments with kidney cells established the choice of buffer and cryoprotectant. A nonstandard temperature of EPM in the suitable buffer was determined. A loss of ionic strength control occurs in the course of preparing columns for flight, the effects of small increases in ionic strength over the expected low values need to be evaluated.

  17. Ammonia release method for depositing metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Silver, G.L.; Martin, F.S.

    1993-12-31

    A method of depositing metal oxides on substrates which is indifferent to the electrochemical properties of the substrates and which comprises forming ammine complexes containing metal ions and thereafter effecting removal of ammonia from the ammine complexes so as to permit slow precipitation and deposition of metal oxide on the substrates.

  18. Growth and micro structural studies on Yittria Stabilized Zirconia (YSZ) and Strontium Titanate (STO) buffer layers

    Energy Technology Data Exchange (ETDEWEB)

    Srinivas, S.; Bhatnagar, A.K. [Univ. of Hyderabad (India); Pinto, R. [Solid State Electronics Group, Bombay (India)] [and others

    1994-12-31

    Microstructure of Yittria Stabilized Zirconia (YSZ) and Strontium Titanate (STO) of radio frequency magnetron sputtered buffer layers was studied at various sputtering conditions on Si<100>, Sapphire and LaAlO{sub 3} <100> substrates. The effect of substrate temperatures upto 800 C and sputtering gas pressures in the range of 50 mTorr. of growth conditions was studied. The buffer layers of YSZ and STO showed a strong tendency for columnar structure with variation growth conditions. The buffer layers of YSZ and STO showed orientation. The tendency for columnar growth was observed above 15 mTorr sputtering gas pressure and at high substrate temperatures. Post annealing of these films in oxygen atmosphere reduced the oxygen deficiency and strain generated during growth of the films. Strong c-axis oriented superconducting YBa{sub 2}Cu{sub 9}O{sub 7-x} (YBCO) thin films were obtained on these buffer layers using pulsed laser ablation technique. YBCO films deposited on multilayers of YSZ and STO were shown to have better superconducting properties.

  19. African American college women's suicide buffers.

    Science.gov (United States)

    Marion, Michelle S; Range, Lillian M

    2003-01-01

    African American women have lower suicide rates than other women and men in the United States They may possess suicide buffers including social support, religiosity, negative attitudes regarding suicide acceptability, and African American culture. To examine the relationships buffers may have with suicide ideation, 300 African American female college students completed measures of suicide ideation and buffers. Three variables accounted for a significant and unique portion of the variance in suicide ideation: family support, a view that suicide is unacceptable, and a collaborative religious problem-solving style. The identification of these factors may help in the assessment, prevention, and intervention of suicide for African American women and other women and men.

  20. Buffer protection in the installation phase

    Energy Technology Data Exchange (ETDEWEB)

    Wimelius, Hans (Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)); Pusch, Roland (Geodevelopment International AB, Lund (Sweden))

    2008-12-15

    The research and development of the design and construction of the SKB's repository for final disposal of spent reactor fuel is conducted along several paths ('lines'). Issues concerning the bedrock are dealt with in the 'rock line' and those related to buffer and backfill in deposition holes and tunnels are considered in the 'buffer line' and 'backfill line', respectively. These lines also deal with sub-activities that are coupled to several other lines. One of them includes development of techniques for protecting buffer blocks from moisture and water in the installation phase. Techniques and methods for placement and removal of the 'buffer protection sheet' are dealt with in the 'buffer line'. The removal is, however, considered as being part of the backfilling sequence. Since the performance of the sheet is of fundamental importance to the placement and function of the buffer it deserves particular attention. Thus, the removal of the rubber sheet that serves to protect the buffer blocks in the installation phase may be difficult and can cause significant problems that may require retrieval of already placed canister, buffer and backfill. These matters are in focus in the present report. Arrangements for protecting already placed buffer blocks from moist air and water have been tested in earlier large-scale experiments, i.e. the Prototype Repository project at Aespoe but the experience from them has called for more effective protection of the clay blocks as described in the present report. Focus is on the construction of foundation components at the bottom of the deposition holes required for establishing a tight seal between rock and buffer blocks, and on the protection sheet and arrangements for limiting water pressure on it. Special attention is paid to the drainage of the space between rock and protection sheet that is necessary for avoiding failure of the sheet and to systems for achieving

  1. Perioperative administration of buffered versus non-buffered crystalloid intravenous fluid to improve outcomes following adult surgical procedures.

    Science.gov (United States)

    Bampoe, Sohail; Odor, Peter M; Dushianthan, Ahilanandan; Bennett-Guerrero, Elliott; Cro, Suzie; Gan, Tong J; Grocott, Michael Pw; James, Michael Fm; Mythen, Michael G; O'Malley, Catherine Mn; Roche, Anthony M; Rowan, Kathy; Burdett, Edward

    2017-09-21

    Perioperative fluid strategies influence clinical outcomes following major surgery. Many intravenous fluid preparations are based on simple solutions, such as normal saline, that feature an electrolyte composition that differs from that of physiological plasma. Buffered fluids have a theoretical advantage of containing a substrate that acts to maintain the body's acid-base status - typically a bicarbonate or a bicarbonate precursor such as maleate, gluconate, lactate, or acetate. Buffered fluids also provide additional electrolytes, including potassium, magnesium, and calcium, more closely matching the electrolyte balance of plasma. The putative benefits of buffered fluids have been compared with those of non-buffered fluids in the context of clinical studies conducted during the perioperative period. This review was published in 2012, and was updated in 2017. To review effects of perioperative intravenous administration of buffered versus non-buffered fluids for plasma volume expansion or maintenance, or both, on clinical outcomes in adults undergoing all types of surgery. We electronically searched the Clinicaltrials.gov major trials registry, the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 6) in the Cochrane Library, MEDLINE (1966 to June 2016), Embase (1980 to June 2016), and the Cumulative Index to Nursing and Allied Health Literature (CINAHL; 1982 to June 2016). We handsearched conference abstracts and, when possible, contacted leaders in the field. We reran the search in May 2017. We added one potential new study of interest to the list of 'Studies awaiting classification' and will incorporate this trial into formal review findings when we prepare the review update. Only randomized controlled trials that compared buffered versus non-buffered intravenous fluids for surgical patients were eligible for inclusion. We excluded other forms of comparison such as crystalloids versus colloids and colloids versus different colloids. Two review

  2. Metal Oxide Sol-Gels (ZrO2, AlO(OH, and SiO2 to Improve the Mechanical Performance of Wood Substrates

    Directory of Open Access Journals (Sweden)

    Véronic Landry

    2013-01-01

    Full Text Available Wood is a renewable material widely used in many applications due to its unique properties and distinctive look. However, as wood is organically constituted, it is slowly destroyed by the long-term impact of oxygen, UV radiations, water, and biological attacks (Mahltig et al., 2008. Therefore, protective treatments are necessary to improve the mechanical, thermal, and chemical properties of wood. In order to improve the mechanical properties of sugar maple (Acer saccharum Marsh., as this species is widely used in the wood products industry, samples of sugar maple were impregnated with sols of metal oxides (AlO(OH, SiO2, and ZrO2. The weight gain and two different techniques of microscopy were used to evaluate the efficiency of the impregnation in the wood samples. The mechanical properties were evaluated using hardness test, scratch test, and impact test. It was shown that the maple samples impregnated with ZrO2 led to the greatest improvement of the mechanical properties.

  3. Morphology and wettability of ZnO nanostructures prepared by hydrothermal method on various buffer layers

    Science.gov (United States)

    Li, Bao-jia; Huang, Li-jing; Zhou, Ming; Ren, Nai-fei

    2013-12-01

    Zinc oxide (ZnO) nanostructures were prepared by hydrothermal method on glass substrates with various buffer layers: Ag, Al, aluminum-doped zinc oxide (AZO) and tin-doped indium oxide (ITO). The structure, morphology and wettability of the ZnO nanostructured surfaces were investigated by using X-ray diffraction, scanning electron microscopy and water contact angle (WCA) analysis methods, respectively. All the nanostructures grown on glass with various buffer layers exhibited strong growth orientation along the (1 0 1) plane. The nature of the buffer layer was found to have remarkable effect on the morphology and wettability of the ZnO nanostructures. Whether the buffer layers were hydrophilic or low hydrophobic, all the ZnO nanostructures grown on the various buffer layers showed high hydrophobic property, and that grown on the AZO buffer layer even exhibited superhydrophobicity with a WCA of 151.1°. This work may provide a scientific basis for self-cleaning ZnO-based optoelectronic device applications.

  4. New superjuction LDMOS with surface and bulk electric field modulation by buffered step doping and multi floating buried layers

    Science.gov (United States)

    Cao, Zhen; Duan, Baoxing; Yuan, Song; Shi, Tongtong; Yang, Yintang

    2017-11-01

    A new superjunction lateral double diffused MOSFET with surface and bulk electric field modulation (SBEFM SJ-LDMOS) by applying of multiple floating buried layers and buffered step doping is proposed in this paper. The Multiple N-type floating buried layers are embedded in P-substrate, to reduce the amount of field crowding at N+/N-buffer/P-substrate junction by spreading the vertical depletion layer, which effectively improves the bulk electric field distribution in SJ-LDMOS, and the N+/N-buffer/P-substrate junction and the auxiliary MFB layers/substrate junctions jointly sustain a high vertical breakdown voltage (BV). In addition, based on the buffered step doping layer under the SJ layer, a uniform lateral electric field at the drift region surface of the device is obtained. Therefore, the bulk and surface electric field are both optimized simultaneously in SBEFM SJ-LDMOS. Simulated results show that compared with the conventional Buffered SJ-LDMOS and BSD SJ-LDMOS, the proposed SBEFM SJ-LDMOS improves BV by 131.7% and 80.4%, respectively, at the same drift region length and with low specific ON-resistance (RON,sp). SBEFM SJ-LDMOS exhibits excellent performance with the power figure-of-merit (FOM=BV2/RON,sp) of 13.07 MW/cm2.

  5. Liquid growth hormone: preservatives and buffers

    DEFF Research Database (Denmark)

    Kappelgaard, Anne-Marie; Anders, Bojesen; Skydsgaard, Karen

    2004-01-01

    Xx showed that pain perception was similar between formulations containing phenol and benzyl alcohol, whereas m-cresol was associated with more painful injections than benzyl alcohol. Furthermore, patients reported more pain following injection of a citrate-buffered solution than after a histidine...... administration. The formulation uses phenol (3 mg/ml) as a preservative (to protect product from microbial degradation or contamination) and histidine as a buffer. Alternative preservatives used in other GH formulations include m-cresol (9 mg/ml) and benzyl alcohol (3-9 mg/ml). Buffering agents include citrate...... been observed following subcutaneous administration of phenol (7.5 mg/ml), m-cresol (3-4 mg/ml) and benzyl alcohol (9 mg/ml). No general toxicity reactions were observed after subcutaneous administration of these agents. Clinical evaluation of the preservatives and buffers used in Norditropin Simple...

  6. The buffer effect in neutral electrolyte supercapacitors

    DEFF Research Database (Denmark)

    Thrane Vindt, Steffen; Skou, Eivind M.

    2016-01-01

    to a change in the redox potential of water in opposite directions on the two electrodes, resulting in the wider stability window. The magnitude of this effect is suggested to be dependent on the buffer capacity, rather than the intrinsic pH value of the electrolyte. This is confirmed by studying the impact...... of addition of a buffer to such systems. It is shown that a 56 % higher dynamic storage capacity may be achieved, simply by controlling the buffer capacity of the electrolyte. The model system used, is based on a well-known commercial activated carbon (NORIT™ A SUPRA) as the electrode material, aqueous...... potassium nitrate as the electrolyte and potassium phosphates as the buffer system....

  7. Calculating Buffer Zones: A Guide for Applicators

    Science.gov (United States)

    Buffer zones provide distance between the application block (i.e., edge of the treated field) and bystanders, in order to control pesticide exposure risk from soil fumigants. Distance requirements may be reduced by credits such as tarps.

  8. Moisture Buffer Value of Building Materials

    DEFF Research Database (Denmark)

    Rode, Carsten; Peuhkuri, Ruut; Time, Berit

    2007-01-01

    When building materials are in contact with indoor air they have some effect to moderate the variations of indoor humidity in occupied buildings. But so far there has been a lack of a standardized quantity to characterize the moisture buffering capability of materials. It has been the objective...... of a recent Nordic project to define such a quantity, and to declare it in the form of a NORDTEST method. The Moisture Buffer Value is the figure that has been developed in the project as a way to appraise the moisture buffer effect of materials, and the value is described in the paper. Also explained...... is a test protocol which expresses how materials should be tested for determination of their Moisture Buffer Value. Finally, the paper presents some of the results of a Round Robin Test on various typical building materials that has been carried out in the project....

  9. Moisture buffer capacity of different insulation materials

    DEFF Research Database (Denmark)

    Peuhkuri, Ruut Hannele; Rode, Carsten; Hansen, Kurt Kielsgaard

    2004-01-01

    lead to more durable constructions. In this paper, a large range of very different thermal insulation materials have been tested in specially constructed laboratory facilities to determine their moisture buffer capacity. Both isothermal and nonisothermal experimental set-ups have been used...... are discussed, and different ways are presented how to determine the moisture buffer capacity of the materials using partly standard material parameters and partly parameters determined from the actual measurements. The results so far show that the determination of moisture buffer capacity is very sensitive...... to the used analysis method and therefore great care has to be taken when comparing results of different experiments. This paper discusses this issue and will come with a recommendation of a simple and consistent way to present the moisture buffer capacity of the materials in contact with the indoor air...

  10. Method of Joining Graphite Fibers to a Substrate

    Science.gov (United States)

    Beringer, Durwood M. (Inventor); Caron, Mark E. (Inventor); Taddey, Edmund P. (Inventor); Gleason, Brian P. (Inventor)

    2014-01-01

    A method of assembling a metallic-graphite structure includes forming a wetted graphite subassembly by arranging one or more layers of graphite fiber material including a plurality of graphite fibers and applying a layer of metallization material to ends of the plurality of graphite fibers. At least one metallic substrate is secured to the wetted graphite subassembly via the layer of metallization material.

  11. Buffer regulation of calcium puff sequences.

    Science.gov (United States)

    Fraiman, Daniel; Dawson, Silvina Ponce

    2014-02-01

    Puffs are localized Ca(2 +) signals that arise in oocytes in response to inositol 1,4,5-trisphosphate (IP3). They are the result of the liberation of Ca(2 +) from the endoplasmic reticulum through the coordinated opening of IP3 receptor/channels clustered at a functional release site. The presence of buffers that trap Ca(2 +) provides a mechanism that enriches the spatio-temporal dynamics of cytosolic calcium. The expression of different types of buffers along the cell's life provides a tool with which Ca(2 +) signals and their responses can be modulated. In this paper we extend the stochastic model of a cluster of IP3R-Ca(2 +) channels introduced previously to elucidate the effect of buffers on sequences of puffs at the same release site. We obtain analytically the probability laws of the interpuff time and of the number of channels that participate of the puffs. Furthermore, we show that under typical experimental conditions the effect of buffers can be accounted for in terms of a simple inhibiting function. Hence, by exploring different inhibiting functions we are able to study the effect of a variety of buffers on the puff size and interpuff time distributions. We find the somewhat counter-intuitive result that the addition of a fast Ca(2 +) buffer can increase the average number of channels that participate of a puff.

  12. GaN Micromechanical Resonators with Meshed Metal Bottom Electrode

    Directory of Open Access Journals (Sweden)

    Azadeh Ansari

    2015-03-01

    Full Text Available This work describes a novel architecture to realize high-performance gallium nitride (GaN bulk acoustic wave (BAW resonators. The method is based on the growth of a thick GaN layer on a metal electrode grid. The fabrication process starts with the growth of a thin GaN buffer layer on a Si (111 substrate. The GaN buffer layer is patterned and trenches are made and refilled with sputtered tungsten (W/silicon dioxide (SiO2 forming passivated metal electrode grids. GaN is then regrown, nucleating from the exposed GaN seed layer and coalescing to form a thick GaN device layer. A metal electrode can be deposited and patterned on top of the GaN layer. This method enables vertical piezoelectric actuation of the GaN layer using its largest piezoelectric coefficient (d33 for thickness-mode resonance. Having a bottom electrode also results in a higher coupling coefficient, useful for the implementation of acoustic filters. Growth of GaN on Si enables releasing the device from the frontside using isotropic xenon difluoride (XeF2 etch and therefore eliminating the need for backside lithography and etching.

  13. Vanadium dioxide thin film with low phase transition temperature deposited on borosilicate glass substrate

    Energy Technology Data Exchange (ETDEWEB)

    Huang Zhangli; Chen Sihai, E-mail: cshai99@mail.hust.edu.cn; Wang Boqing; Huang Ying; Liu Nengfu; Xu Jin; Lai Jianjun

    2011-04-29

    A nanostructured vanadium dioxide (VO{sub 2}) thin film showing a low metal-insulator transition temperature of 30 {sup o}C has been fabricated through reactive ion beam sputtering followed by thermal annealing. The thin film was grown on borosilicate glass substrate at the temperature of 280 {sup o}C with a Si{sub 3}N{sub 4} buffer layer. Both scanning electron microscopy and atomic force microscopy images have been taken to investigate the configuration of VO{sub 2} thin film. The average height of the crystallite is 20 nm and the grain size ranges from 40 nm to 100 nm. The transmittance measured from low to high temperatures also reveals that the film possesses excellent switching property in infrared light at critical transition temperature, with switching efficiency of 52% at 2600 nm. This experiment paves the way of VO{sub 2} thin film's application in smart windows.

  14. Influence of SiO{sub 2} buffer layer on the crystalline quality and photoluminescence of ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Xu, L H; Chen, Y L; Xu, F [College of Math and Physics, Nanjing University of Information Science and Technology, Nanjing, 210044 (China); Li, X Y [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing, 210094 (China); Hua, S, E-mail: congyu3256@sina.com [Institute of Electronic Engineering and Photoelectric Technology, Nanjing University of Science and Technology, Nanjing, 210094 (China)

    2011-02-01

    In this work, a SiO{sub 2} buffer layer was first grown on Si substrate by thermal oxidation, and then ZnO thin films were deposited on SiO{sub 2} buffer layer and Si substrate by electron beam evaporation and sol-gel method. The influence of SiO{sub 2} buffer layer on the crystalline quality and photoluminescence of the films was investigated. The analyses of X-ray diffraction (XRD) showed that all the ZnO thin films had a hexagonal wurtzite structure and were preferentially oriented along the c-axis perpendicular to the substrate surface. The SiO{sub 2} buffer layer improved the crystalline quality and decreased the stress in ZnO thin films. The surface morphology analyses of the samples indicated that ZnO thin films deposited on SiO{sub 2} buffer layers had densely packed grains which obviously increased compared with those grown on bare Si substrate. The photoluminescence spectra of the samples showed that the ZnO thin films deposited on SiO{sub 2} buffer layers had stronger ultraviolet emission performance. The results suggest that SiO{sub 2} buffer layer can improve the crystalline quality and ultraviolet emission of ZnO thin films.

  15. Efficient inverted bulk-heterojunction solar cells from low-temperature processing of amorphous ZnO buffer layers

    KAUST Repository

    Jagadamma, Lethy Krishnan

    2014-01-01

    In this report, we demonstrate that solution-processed amorphous zinc oxide (a-ZnO) interlayers prepared at low temperatures (∼100 °C) can yield inverted bulk-heterojunction (BHJ) solar cells that are as efficient as nanoparticle-based ZnO requiring comparably more complex synthesis or polycrystalline ZnO films prepared at substantially higher temperatures (150-400 °C). Low-temperature, facile solution-processing approaches are required in the fabrication of BHJ solar cells on flexible plastic substrates, such as PET. Here, we achieve efficient inverted solar cells with a-ZnO buffer layers by carefully examining the correlations between the thin film morphology and the figures of merit of optimized BHJ devices with various polymer donors and PCBM as the fullerene acceptor. We find that the most effective a-ZnO morphology consists of a compact, thin layer with continuous substrate coverage. In parallel, we emphasize the detrimental effect of forming rippled surface morphologies of a-ZnO, an observation which contrasts with results obtained in polycrystalline ZnO thin films, where rippled morphologies have been reported to improve efficiency. After optimizing the a-ZnO morphology at low processing temperature for inverted P3HT:PCBM devices, achieving a power conversion efficiency (PCE) of ca. 4.1%, we demonstrate inverted solar cells with low bandgap polymer donors on glass/flexible PET substrates: PTB7:PC71BM (PCE: 6.5% (glass)/5.6% (PET)) and PBDTTPD:PC71BM (PCE: 6.7% (glass)/5.9% (PET)). Finally, we show that a-ZnO based inverted P3HT:PCBM BHJ solar cells maintain ca. 90-95% of their initial PCE even after a full year without encapsulation in a nitrogen dry box, thus demonstrating excellent shelf stability. The insight we have gained into the importance of surface morphology in amorphous zinc oxide buffer layers should help in the development of other low-temperature solution-processed metal oxide interlayers for efficient flexible solar cells. This journal is

  16. Low noise buffer amplifiers and buffered phase comparators for precise time and frequency measurement and distribution

    Science.gov (United States)

    Eichinger, R. A.; Dachel, P.; Miller, W. H.; Ingold, J. S.

    1982-01-01

    Extremely low noise, high performance, wideband buffer amplifiers and buffered phase comparators were developed. These buffer amplifiers are designed to distribute reference frequencies from 30 KHz to 45 MHz from a hydrogen maser without degrading the hydrogen maser's performance. The buffered phase comparators are designed to intercompare the phase of state of the art hydrogen masers without adding any significant measurement system noise. These devices have a 27 femtosecond phase stability floor and are stable to better than one picosecond for long periods of time. Their temperature coefficient is less than one picosecond per degree C, and they have shown virtually no voltage coefficients.

  17. Buffer-free therapeutic antibody preparations provide a viable alternative to conventionally buffered solutions: from protein buffer capacity prediction to bioprocess applications.

    Science.gov (United States)

    Bahrenburg, Sven; Karow, Anne R; Garidel, Patrick

    2015-04-01

    Protein therapeutics, including monoclonal antibodies (mAbs), have significant buffering capacity, particularly at concentrations>50 mg/mL. This report addresses pH-related issues critical to adoption of self-buffered monoclonal antibody formulations. We evaluated solution conditions with protein concentrations ranging from 50 to 250 mg/mL. Samples were both buffer-free and conventionally buffered with citrate. Samples were non-isotonic or adjusted for isotonicity with NaCl or trehalose. Studies included accelerated temperature stability tests, shaking stability studies, and pH changes in infusion media as protein concentrate is added. We present averaged buffering slopes of capacity that can be applied to any mAb and present a general method for calculating buffering capacity of buffer-free, highly concentrated antibody liquid formulations. In temperature stability tests, neither buffer-free nor conventionally buffered solution conditions showed significant pH changes. Conventionally buffered solutions showed significantly higher opalescence than buffer-free ones. In general, buffer-free solution conditions showed less aggregation than conventionally buffered solutions. Shaking stability tests showed no differences between buffer-free and conventionally buffered solutions. "In-use" preparation experiments showed that pH in infusion bag medium can rapidly approximate that of self-buffered protein concentrate as concentrate is added. In summary, the buffer capacity of proteins can be predicted and buffer-free therapeutic antibody preparations provide a viable alternative to conventionally buffered solutions. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Temperature buffer test design, instrumentation and measurements

    Science.gov (United States)

    Sandén, Torbjörn; Goudarzi, Reza; de Combarieu, Michel; Åkesson, Mattias; Hökmark, Harald

    The Temperature Buffer Test, TBT, is a heated full-scale field experiment carried out jointly by ANDRA and SKB at the SKB Äspö Hard Rock Laboratory in Southeast Sweden. An existing 8 m deep, 1.8 m diameter KBS-3-type deposition hole located at -420 m level has been selected for the test. The objectives are to improve the general understanding of Thermo-Hydro-Mechanical, THM, behavior of buffer materials submitted to severe thermal conditions with temperatures well over 100 °C during water uptake of partly saturated bentonite-based buffer materials, and to check, in due time, their properties after water saturation. The test includes two carbon steel heating canisters each 3 m high and 0.6 m diameter, surrounded by 0.6 m of buffer material. There is a 0.2 m thick sand shield between the upper heater and the surrounding bentonite, while the lower heater is surrounded by bentonite only. On top of the stack of bentonite blocks is a confining plug anchored to the rock. In the slot between buffer and rock wall is a sand filter equipped with pipes to control the water pressure at the boundary, which is seldom done with an EBS in situ experiment. Both heater mid-height planes are densely instrumented in order to follow, with direct or indirect methods, buffer THM evolution. Temperature, relative humidity, stress and pore pressure have been monitored since the test start in March 2003. Total water inflow is also monitored. Firstly, the present paper describes the test design, the instrumentation, the plug anchoring system and the system for water boundary pressure control. Second, having described the test, the paper shows different measurements that illustrate evolution of temperature, saturation, suction and swelling pressure in the upper and the lower buffer.

  19. ssDNA degradation along capillary electrophoresis process using a Tris buffer.

    Science.gov (United States)

    Ric, Audrey; Ong-Meang, Varravaddheay; Poinsot, Verena; Martins-Froment, Nathalie; Chauvet, Fabien; Boutonnet, Audrey; Ginot, Frédéric; Ecochard, Vincent; Paquereau, Laurent; Couderc, François

    2017-06-01

    Tris-Acetate buffer is currently used in the selection and the characterization of ssDNA by capillary electrophoresis (CE). By applying high voltage, the migration of ionic species into the capillary generates a current that induces water electrolysis. This phenomenon is followed by the modification of the pH and the production of Tris derivatives. By injecting ten times by capillary electrophoresis ssDNA (50 nM), the whole oligonucleotide was degraded. In this paper, we will show that the Tris buffer in the running vials is modified along the electrophoretic process by electrochemical reactions. We also observed that the composition of the metal ions changes in the running buffer vials. This phenomenon, never described in CE, is important for fluorescent ssDNA analysis using Tris buffer. The oligonucleotides are degraded by electrochemically synthesized species (present in the running Tris vials) until it disappears, even if the separation buffer in the capillary is clean. To address these issues, we propose to use a sodium phosphate buffer that we demonstrate to be electrochemically inactive. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. A substrate and a method of using it

    DEFF Research Database (Denmark)

    2016-01-01

    A substrate for a plurality of different measurement set-ups such as SERS, SPR and LSPR which substrate has a base and a plurality of elongate elements with metallic tips. A metallic layer is present on the base surface between the elongate elements and gaps or cavities exist between the layer an...

  1. Power electronics substrate for direct substrate cooling

    Science.gov (United States)

    Le, Khiet [Mission Viejo, CA; Ward, Terence G [Redondo Beach, CA; Mann, Brooks S [Redondo Beach, CA; Yankoski, Edward P [Corona, CA; Smith, Gregory S [Woodland Hills, CA

    2012-05-01

    Systems and apparatus are provided for power electronics substrates adapted for direct substrate cooling. A power electronics substrate comprises a first surface configured to have electrical circuitry disposed thereon, a second surface, and a plurality of physical features on the second surface. The physical features are configured to promote a turbulent boundary layer in a coolant impinged upon the second surface.

  2. Scientific Applications Performance Evaluation on Burst Buffer

    KAUST Repository

    Markomanolis, George S.

    2017-10-19

    Parallel I/O is an integral component of modern high performance computing, especially in storing and processing very large datasets, such as the case of seismic imaging, CFD, combustion and weather modeling. The storage hierarchy includes nowadays additional layers, the latest being the usage of SSD-based storage as a Burst Buffer for I/O acceleration. We present an in-depth analysis on how to use Burst Buffer for specific cases and how the internal MPI I/O aggregators operate according to the options that the user provides during his job submission. We analyze the performance of a range of I/O intensive scientific applications, at various scales on a large installation of Lustre parallel file system compared to an SSD-based Burst Buffer. Our results show a performance improvement over Lustre when using Burst Buffer. Moreover, we show results from a data hierarchy library which indicate that the standard I/O approaches are not enough to get the expected performance from this technology. The performance gain on the total execution time of the studied applications is between 1.16 and 3 times compared to Lustre. One of the test cases achieved an impressive I/O throughput of 900 GB/s on Burst Buffer.

  3. The use of 0.01M phosphate buffered saline as detection buffer for ...

    African Journals Online (AJOL)

    This study aimed at evaluating the use of 0.01M phosphate buffered saline (PBS) as detection buffer for Alere Determine® HIV rapid test. This study was carried out at Bugando School of Medicine in Mwanza, Tanzania. A total of 300 whole blood specimens; 150 HIV positive specimens from patients attending Care and ...

  4. Vegetative buffer strips for reducing herbicide transport in runoff: effects of season, vegetation, and buffer width

    Science.gov (United States)

    The effectiveness of vegetative buffer strips (VBS) for reducing herbicide transport in runoff may be affected by season, plant species composition, and buffer width. A plot-scale study was conducted from 2007-2012 on an eroded claypan soil with the objectives of: 1) assessing the effects of season ...

  5. Crystallinity Improvement of ZnO Thin Film on Different Buffer Layers Grown by MBE

    Directory of Open Access Journals (Sweden)

    Shao-Ying Ting

    2012-01-01

    Full Text Available The material and optical properties of ZnO thin film samples grown on different buffer layers on sapphire substrates through a two-step temperature variation growth by molecular beam epitaxy were investigated. The thin buffer layer between the ZnO layer and the sapphire substrate decreased the lattice mismatch to achieve higher quality ZnO thin film growth. A GaN buffer layer slightly increased the quality of the ZnO thin film, but the threading dislocations still stretched along the c-axis of the GaN layer. The use of MgO as the buffer layer decreased the surface roughness of the ZnO thin film by 58.8% due to the suppression of surface cracks through strain transfer of the sample. From deep level emission and rocking curve measurements it was found that the threading dislocations play a more important role than oxygen vacancies for high-quality ZnO thin film growth.

  6. Nonlinear spelling in graphemic buffer deficit.

    Science.gov (United States)

    Schubert, Teresa; Nickels, Lyndsey

    2015-01-01

    In this paper, we describe a case of nonlinear spelling and its implications for theories of the graphemic buffer. C.T.J., an individual with an acquired deficit of the graphemic buffer, often wrote the letters of his responses in a nonlinear temporal order when writing to dictation. The spatial ordering of the letters was maintained: Letters in the later positions of the words were written towards the right side of the response, even when written before letters in earlier positions. This unusual phenomenon has been briefly reported in three prior cases but this study provides the most detailed analysis of the phenomenon to date. We specifically contend that the decoupling of the temporal and spatial aspects of spelling is difficult to reconcile with competitive queuing accounts of the graphemic buffer.

  7. Hafnium nitride buffer layers for growth of GaN on silicon

    Science.gov (United States)

    Armitage, Robert D.; Weber, Eicke R.

    2005-08-16

    Gallium nitride is grown by plasma-assisted molecular-beam epitaxy on (111) and (001) silicon substrates using hafnium nitride buffer layers. Wurtzite GaN epitaxial layers are obtained on both the (111) and (001) HfN/Si surfaces, with crack-free thickness up to 1.2 {character pullout}m. However, growth on the (001) surface results in nearly stress-free films, suggesting that much thicker crack-free layers could be obtained.

  8. Buffering action of acetate on hydrogen production by Ethanoligenens harbinense B49

    Directory of Open Access Journals (Sweden)

    Ji-Fei Xu

    2016-09-01

    Full Text Available The buffering effect of acetate on hydrogen production during glucose fermentation by Ethanoligenens harbinense B49 was investigated compared to phosphate, a widely used fermentative hydrogen production buffer. Specific concentrations of sodium acetate or phosphate were added to batch cultures, and the effects on hydrogen production were comparatively analyzed using a modified Gompertz model. Adding 50 mM acetate or phosphate suppressed the hydrogen production peak and slightly extended the lag phase. However, the overall hydrogen yields were 113.5 and 108.5 mmol/L, respectively, and the final pH was effectively controlled. Acetate buffered against hydrogen production more effectively than did phosphate, promoting cell growth and preventing decreased pH. At buffer concentrations 100–250 mM, the maximum hydrogen production was barely suppressed, and the lag phase extended past 7 h. Therefore, although acetate inhibits hydrogen production, using acetate as a buffer (like phosphate effectively prevented pH drops and increased substrate consumption, enhancing hydrogen production.

  9. Phytostabilization of metals by indigenous riparian vegetation ...

    African Journals Online (AJOL)

    When measured against an ideal hypothetical buffer zone, the buffer zones under investigation varied between intact and severely compromised. Intact riparian zones showed elevated metal concentrations in the soil, yet significantly lower concentrations in the river water compared to areas with insufficient vegetative cover ...

  10. [Antigen retrieval by microwave oven with buffer of citric acid].

    Science.gov (United States)

    Pellicer, E M; Sundblad, A

    1994-01-01

    Microwave oven (mwo) is used to stimulate tissue fixation and to retrieve antigens damaged by fixation. Heavy metal salt solutions, water, and citric acid buffer (cab) have been suggested for this purpose. A serie of tumors treated with cab and phosphate-buffered saline (pbs) with mwo were studied immunohistochemically with 24 antibodies. Controls were treated in the same way, except for microwaving. The antibodies were directed against antigens of the following tumors: breast and prostate carcinoma, carcinoid, lymphoma and melanoma. The results showed that cab enhanced the immunoreactivity of the following antigens: estrogen receptors (AMAC), progesterone receptors (Novocastra), HMB45, vimentin, leukocyte common antigen, PCNA, p53, MIB-1 (Ki-67) and prostatic specific antigen. The antigens that did not improve their immunoreactivity, when compared with the control series were: factor VIII, keratin, Leu 22, L26, neuron-specific enolase, CEA, chromogranin, HBME-1, smooth muscle actin and EMA. Microwaving equally improved protein S100 and desmin either with cab or pbs. The only antigen that improved with pbs was actin. The results with B72.3 and NKI/C3 were poor and not reliable. In conclusion microwaving with cab enhances the immunoreactivity of the antibodies mentioned above leading to an increase in sensibility without loosing specificity.

  11. Grass buffers for playas in agricultural landscapes: An annotated bibliography

    Science.gov (United States)

    Melcher, Cynthia P.; Skagen, Susan K.

    2005-01-01

    This bibliography and associated literature synthesis (Melcher and Skagen, 2005) was developed for the Playa Lakes Joint Venture (PLJV). The PLJV sought compilation and annotation of the literature on grass buffers for protecting playas from runoff containing sediments, nutrients, pesticides, and other contaminants. In addition, PLJV sought information regarding the extent to which buffers may attenuate the precipitation runoff needed to fill playas, and avian use of buffers. We emphasize grass buffers, but we also provide information on other buffer types.

  12. The roles of buffer layer thickness on the properties of the ZnO epitaxial films

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Kun, E-mail: ktang@nju.edu.cn [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Huang, Shimin [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Gu, Shulin, E-mail: slgu@nju.edu.cn [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Zhu, Shunming [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Ye, Jiandong [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Nanjing University Institute of Optoelectronics at Yangzhou, Yangzhou 225009 (China); Xu, Zhonghua; Zheng, Youdou [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China)

    2016-12-01

    Highlights: • The growth mechanism has been revealed for the ZnO buffers with different thickness. • The surface morphology has been determined as the key factor to affect the epitaxial growth. • The relation between the hexagonal pits from buffers and epi-films has been established. • The hexagonal pits formed in the epi-films have been attributed to the V-shaped defects inheriting from the dislocations in the buffers. • The structural and electrical properties of the V-defects have been presented and analyzed. - Abstract: In this article, the authors have investigated the optimization of the buffer thickness for obtaining high-quality ZnO epi-films on sapphire substrates. The growth mechanism of the buffers with different thickness has been clearly revealed, including the initial nucleation and vertical growth, the subsequent lateral growth with small grain coalescence, and the final vertical growth along the existing larger grains. Overall, the quality of the buffer improves with increasing thickness except the deformed surface morphology. However, by a full-scale evaluation of the properties for the epi-layers, the quality of the epi-film is briefly determined by the surface morphology of the buffer, rather than the structural, optical, or electrical properties of it. The best quality epi-layer has been grown on the buffer with a smooth surface and well-coalescent grains. Meanwhile, due to the huge lattice mismatch between sapphire and ZnO, dislocations are inevitably formed during the growth of buffers. More importantly, as the film grows thicker, the dislocations may attracting other smaller dislocations and defects to reduce the total line energy and thus result in the formation of V-shape defects, which are connected with the bottom of the threading dislocations in the buffers. The V-defects appear as deep and large hexagonal pits from top view and they may act as electron traps which would affect the free carrier concentration of the epi-layers.

  13. MOCVD growth of N-polar GaN on on-axis sapphire substrate: Impact of AlN nucleation layer on GaN surface hillock density

    Science.gov (United States)

    Marini, Jonathan; Leathersich, Jeffrey; Mahaboob, Isra; Bulmer, John; Newman, Neil; (Shadi) Shahedipour-Sandvik, F.

    2016-05-01

    We report on the impact of growth conditions on surface hillock density of N-polar GaN grown on nominally on-axis (0001) sapphire substrate by metal organic chemical vapor deposition (MOCVD). Large reduction in hillock density was achieved by implementation of an optimized high temperature AlN nucleation layer and use of indium surfactant in GaN overgrowth. A reduction by more than a factor of five in hillock density from 1000 to 170 hillocks/cm-2 was achieved as a result. Crystal quality and surface morphology of the resultant GaN films were characterized by high resolution x-ray diffraction and atomic force microscopy and found to be relatively unaffected by the buffer conditions. It is also shown that the density of smaller surface features is unaffected by AlN buffer conditions.

  14. Defining Steamside Management Zones or Riparian Buffers

    Science.gov (United States)

    Thomas M. Williams; Donald J. Lipscomb; Christopher J. Post

    2004-01-01

    Forestry Best Management Practices (BMPs) have been highly successful in protecting water quality throughout the Southeast. Numerous studies have found them to be effective in protecting water quality. Despite being mostly voluntary, compliance is generally about 90 percent across the region. Streamside Management Zones (SMZs) or riparian buffers are specified for...

  15. Zelfzorg als buffer voor burn-out

    OpenAIRE

    Damman, Caroline; Dewaele, Bart

    2015-01-01

    Burn-out komt vaak voor bij hulpverleners. Door hun eigenheid durven ze niet snel hulp vragen. In geen enkele missietekst van een organisatie staat dat de organisatie zelfzorg bij hulpverleners als kerntaak opneemt. Zelfzorg is de beste buffer tegen burn-out.

  16. The buffer effect in neutral electrolyte supercapacitors

    Science.gov (United States)

    Vindt, Steffen T.; Skou, Eivind M.

    2016-02-01

    The observation that double-layer capacitors based on neutral aqueous electrolytes can have significantly wider usable potential windows than those based on acidic or alkaline electrolytes is studied. This effect is explained by a local pH change taking place at the electrode surfaces, leading to a change in the redox potential of water in opposite directions on the two electrodes, resulting in the wider stability window. The magnitude of this effect is suggested to be dependent on the buffer capacity, rather than the intrinsic pH value of the electrolyte. This is confirmed by studying the impact of addition of a buffer to such systems. It is shown that a 56 % higher dynamic storage capacity may be achieved, simply by controlling the buffer capacity of the electrolyte. The model system used, is based on a well-known commercial activated carbon (NORIT™ A SUPRA) as the electrode material, aqueous potassium nitrate as the electrolyte and potassium phosphates as the buffer system.

  17. Buffering children from marital conflict and dissolution.

    Science.gov (United States)

    Katz, L F; Gottman, J M

    1997-06-01

    Examined several protective mechanisms that may reduce deleterious correlates of marital conflict and marital dissolution in young children. One set of potential buffers focused on parent-child interaction: parental warmth, parental scaffolding/praise, and inhibition of parental rejection. As a second set of potential buffers, each parent was interviewed about their "meta-emotion philosophy"--that is, their feelings about their own emotions, and their attitudes and responses to their children's anger and sadness. The third set of potential buffers concerned intraindividual characteristics of the child, including the child's intelligence and regulatory physiology (basal vagal tone and vagal suppression). Fifty-six families with a preschool child were studied at two time points: when the children were 5 years old (Time 1) and again when the children were 8 years old (Time 2). At Time 1, naturalistic observations of marital and parent-child interaction were conducted and assessment of child regulatory physiology was obtained through measures of basal vagal tone and suppression of vagal tone. Parents were also interviewed individually about their feelings about their own and their children's emotions, and children's intelligence was assessed. At Time 2, assessment of child outcomes were obtained, including observations of peer interaction, mother ratings of behavior problems and mother and teacher ratings of peer aggression, mother ratings of child physical illness, and measures of achievement. Results indicated that all Time 1 buffering factors protected children in face of marital conflict and dissolution.

  18. Multiaxis sensing using metal organic frameworks

    Science.gov (United States)

    Talin, Albert Alec; Allendorf, Mark D.; Leonard, Francois; Stavila, Vitalie

    2017-01-17

    A sensor device including a sensor substrate; and a thin film comprising a porous metal organic framework (MOF) on the substrate that presents more than one transduction mechanism when exposed to an analyte. A method including exposing a porous metal organic framework (MOF) on a substrate to an analyte; and identifying more than one transduction mechanism in response to the exposure to the analyte.

  19. TITANIA-COATINGS ON STRONGLY PASSIVATED SUBSTRATES

    OpenAIRE

    Haenni, W.; Hintermann, H.; Morel, D.; Simmen, A.

    1989-01-01

    Titanium oxide can be deposited by pyrolysis of the corresponding alkoxide on metallic substrates after their preoxidation by water-vapor. To improve adhesion, the natural oxide film has first to be removed mechanically and/or chemically from the strongly passivated substrates, such as aluminium, titanium, alloys thereof, stainless steel and super-alloys. To completely remove the oxide film on AISI 316L stainless steel and similar alloys, chemical vapor etching is necessary. The preoxidation ...

  20. Growth and characterization of {beta}-In N films on Mg O: the key role of a {beta}-Ga N buffer layer in growing cubic In N

    Energy Technology Data Exchange (ETDEWEB)

    Navarro C, H.; Perez C, M.; Rodriguez, A. G.; Lopez L, E.; Vidal, M. A. [Universidad Autonoma de San Luis Potosi, Coordinacion para la Innovacion y la Aplicacion de la Ciencia y la Tecnologia, Alvaro Obregon 64, 78000 San Luis Potosi (Mexico)

    2012-07-01

    Cubic In N samples were grown on Mg O (001) substrates by gas source molecular beam epitaxy. In general, we find that In N directly deposited onto the Mg O substrate results in polycrystalline or columnar films of hexagonal symmetry. We find that adequate conditions to grow the cubic phase of this compound require the growth of an initial cubic Ga N buffer interlayer ({beta}-t Ga N) on the Mg O surface. Subsequently, the growth conditions were optimized to obtain good photoluminescence (Pl) emission. The resultant In N growth is mostly cubic, with very small hexagonal inclusions, as confirmed by X-ray diffraction and scanning electron microscopy studies. Good crystalline quality requires that the samples to be grown under rich Indium metal flux. The cubic {beta}-t In N/Ga N/Mg O samples exhibit a high signal to noise ratio for Pl at low temperatures (20 K). The Pl is centered at O.75 eV and persist at room temperature. (Author)

  1. Substrate Integrated Waveguide (SIW Coupler on Green Material Substrate for Internet of Things (IoT Applications

    Directory of Open Access Journals (Sweden)

    Khalid Nurehansafwanah

    2017-01-01

    Full Text Available This paper shows designed coupler on paper-substrate with Substrate Integrated Waveguide (SIW techniques. Types of paper-substrate that used are photographic paper. The rectangular coupler is presented with Substrate Integrated Waveguide (SIW which metallic via on paper-substrate. The structures of the coupler are designed and analysed using Computer Simulation Tools (CST Studio Suite 2014 Software. This designed coupler operating within frequency of 3.8-5 GHz. The paper-based substrates are permits the implementation of green materials (Eco-friendly technology. The design of the coupler and its simulated results are reported in this paper.

  2. In situ observation of surface reactions with synchrotron radiation induced semiconductor processes by infrared reflection absorption spectroscopy using buried metal layer substrates; Umekomi kinzokuso kiban wo mochiita sekigai hansha kyushu supekutoruho ni yoru hoshako reiki handotai process hanno no sonoba kansatsu

    Energy Technology Data Exchange (ETDEWEB)

    Yoshigoe, A.; Hirano, S. [The Graduate University for Advanced Studies, Yokohama (Japan); Mase, K.; Urisu, T. [Institute for Molecular Science, Aichi (Japan)

    1996-11-20

    It is known that infrared reflection absorption spectroscopy (IRAS) on semiconductor or insulator surfaces becomes practicable by using buried metal layer (BML) substrates, in which the metal thin film is buried order semiconductor or insulator films. In this work, IRAS has been measured for Langmuir-Blodgett films deposited on the BML substrate with SiO2/Al/Si(100) structure and the observed spectrum intensity has been quantitatively compared with the calculation assuming the ideal multilayer structure for the BML substrate. The BML-IRAS using CoSi2 has been adopted to the detection of SiHn on the Si (100) substrate during synchrotron radiation (SR) stimulated Si2H6 gas source molecular beam epitaxy. It has been found that SiH2 and SiH3 on the Si (100) surface are easily decomposed by SR, but SiH can`t be decomposed. From these experiments, it has been concluded that the BML-IRAS is an useful in situ observation technique for the photo-stimulated surface reactions. 26 refs., 9 figs.

  3. Metal deposition using seed layers

    Science.gov (United States)

    Feng, Hsein-Ping; Chen, Gang; Bo, Yu; Ren, Zhifeng; Chen, Shuo; Poudel, Bed

    2013-11-12

    Methods of forming a conductive metal layers on substrates are disclosed which employ a seed layer to enhance bonding, especially to smooth, low-roughness or hydrophobic substrates. In one aspect of the invention, the seed layer can be formed by applying nanoparticles onto a surface of the substrate; and the metallization is achieved by electroplating an electrically conducting metal onto the seed layer, whereby the nanoparticles serve as nucleation sites for metal deposition. In another approach, the seed layer can be formed by a self-assembling linker material, such as a sulfur-containing silane material.

  4. GaAs/Ge/Si epitaxial substrates: Development and characteristics

    Directory of Open Access Journals (Sweden)

    Yury Buzynin

    2017-01-01

    Full Text Available We developed high quality 2-inch GaAs/Ge/Si (100 epitaxial substrates, which may be used instead of GaAs monolithic substrates for fabrication of solar cells, photodetectors, LEDs, lasers, etc. A 200–300 nm Ge buffer layer was grown on Si substrates using the HW-CVD technique at 300°C, a tantalum strip heated to 1400°C was used as the “hotwire”. The MOCVD method was used to grow a 1 μ GaAs layer on a Ge buffer. The TDD in the GaAs layers did not exceed (1–2∙105 cm-2 and the surface RMS roughness value was under 1 nm.

  5. Preferred oriented ZnO films growth on nonoriented substrates by CVD

    Science.gov (United States)

    Abduev, A.; Akhmedov, A.; Asvarov, A.; Omaev, A.

    2012-02-01

    The processes of CVD synthesis of ZnO layers with different preferred orientation on non-crystalline substrates where studied. Synthesis was carried out in a hydrogen atmosphere on substrates with ZnO buffer layers with various preferred orientation, namely in the plane perpendicular as well as parallel to plane of the substrate. ZnO buffer layers were synthesized by magnetron sputtering of ZnO ceramic targets. Conditions for the ZnO layers formation by CVD with (002), (100), (110) preferred orientations and mixed (100) - (110) orientations were determined.

  6. Influence of the metal ion on the enzyme activity and kinetics of PepA from Lactobacillus delbrueckii.

    Science.gov (United States)

    Ewert, Jacob; Glück, Claudia; Strasdeit, Henry; Fischer, Lutz; Stressler, Timo

    2018-03-01

    The aminopeptidase A (PepA; EC 3.4.11.7) belongs to the group of metallopeptidases with two bound metal ions per subunit (M1M2(PepA)) and is specific for the cleavage of N-terminal glutamic (Glu) and aspartic acid (Asp) and, in low amounts, serine (Ser) residues. Our group recently characterized the first PepA from a Lactobacillus strain. However, the characterization was performed using synthetic para-nitroaniline substrates and not original peptide substrates, as was done in the current study. Prior to the characterization using original peptide substrates, the PepA purified was converted to its inactive apo-form and eight different metal ions were tested to restore its activity. It was found that five of the metal ions were able to reactivate apo-PepA: Co2+, Cu2+, Mn2+, Ni2+ and Zn2+. Interestingly, depending on the metal ion used for reactivation, the activity and the pH and temperature profile differed. Exemplarily, MnMn(PepA), NiNi(PepA) and ZnZn(PepA) had an activity optimum using MES buffer (50mM, pH 6.0) and 60°C, whereas the activity optimum changed to Na/K-phosphate-buffer (50mM, pH 7.0) and 55°C for CuCu(PepA). However, more important than the changes in optimum pH and temperature, the kinetic properties of PepA were affected by the metal ion used. While all PepA variants could release N-terminal Glu or Asp, only CoCo(PepA), NiNi(PepA) and CuCu(PepA) could release Ser from the particular peptide substrate. In addition, it was found that the enzyme efficiency (Vmax/KM) and catalytic mechanism (positive cooperative binding (Hill coefficent; n), substrate inhibition (KIS)) were influenced by the metal ion. Exemplarily, a high cooperativity (n>2),KIS value >20mM and preference for N-terminal Glu were detected for CuCu(PepA). In summary, the results suggested that an exchange of the metal ion can be used for tailoring the properties of PepA for specific hydrolysis requirements. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Inkjet-Printed Chemical Solution Y2O3 Layers for Planarization of Technical Substrates

    Directory of Open Access Journals (Sweden)

    Marta Vilardell

    2017-12-01

    Full Text Available The implementation of the Chemical Solution Deposition (CSD methodology with the Drop on Demand (DoD inkjet printing (IJP technology has been successfully employed to develop a Solution Deposition Planarization (SDP method. We have used nanocrystalline yttrium oxide (Y2O3 to decrease the roughness of technical metallic substrates by filling the surface imperfections and thus avoiding costly polishing steps. This alternative process represents an outstanding methodology to reduce the final cost of the second-generation coated conductors manufacturing. Two Y2O3 metalorganic precursor ink formulations were successfully developed and tested to obtain surfaces as smooth as possible with adequate mechanical properties to hold the internal stress developed during the growth of the subsequent layers. By using these inks as precursors for IJP and after a proper tuning of the rheological and wetting parameters, we firstly obtained centimeter length uniform 100 nm-thick SDP-Y2O3 films on unpolished stainless-steel substrate from Bruker HTS. The scalability of the roll to roll (R2R-IJP process to 100 m is then demonstrated on metallic substrates as well. A complete characterization of the prepared SDP-Y2O3 inkjet-printed layers was carried out using optical microscopy, FIB-SEM (Focus Ion Beam coupled to Scanning Electron Microscopy, XRD (X-ray Diffraction, AFM (Atomic Force Microscopy, reflectometry and nanoindentation techniques. Then, the morphology, thickness, crystallinity and mechanical properties were evaluated, together with the surface roughness in order to assess the resulting layer planarity. The impact of planarity was additionally studied via growth of biaxially textured buffer layers as well as further functional layers. 1.1 µm-thick YSZ layers with in-plane textures better than the stainless steel (SS polished reference were successfully deposited on top of 100 nm SDP-Y2O3 films yielding 50% of Ic in contrast to the standard SS reference.

  8. Nanowires-based light emitters on thermally and electrically conductive substrates and of making same

    KAUST Repository

    Ooi, Boon S.

    2017-04-27

    Elemental or compound semiconductors on metal substrates and methods of growing them are provided. The methods can include the steps of: (i) providing a metal substrate; (ii) adding an interlayer on a surface of the metal substrate, and (iii) growing semiconductor nanowires on the interlayer using a semiconductor epitaxy growth system to form the elemental or compound semiconductor. The method can include direct growth of high quality group III-V and group III-N based materials in the form of nanowires and nanowires-based devices on metal substrates. The nanowires on all- metal scheme greatly simplifies the fabrication process of nanowires based high power light emitters.

  9. High efficiency quantum dot and organic LEDs with a back-cavity and a high index substrate

    Science.gov (United States)

    Liang, Haowen; Luo, Zhenyue; Zhu, Ruidong; Dong, Yajie; Lee, Jiun-Haw; Zhou, Jianying; Wu, Shin-Tson

    2016-04-01

    We report a back-cavity design to enhance the optical efficiency of a quantum dot light-emitting diode (QLED) or an organic light-emitting diode (OLED) for display and lighting applications. Our simulation results show that the back-cavity design exhibits two major advantages: (1) the transparent electrode helps to increase the transmittance of backward light despite using a semi-transparent metal electrode, and (2) the thickness of the low index optical buffer layer can be optimized to modify the proportion of each optical channel. The proposed back-cavity also helps to lower the refractive index of the high-index substrate from ~2.0 to ~1.8 for achieving high optical efficiency. Finally, the introduced back-cavity does not degrade the color performance of the QLED/OLED.

  10. Hydrothermal ore-forming processes in the light of studies in rock- buffered systems: II. Some general geologic applications

    Science.gov (United States)

    Hemley, J.J.; Hunt, J.P.

    1992-01-01

    The experimental metal solubilities for rock-buffered hydrothermal systems provide important insights into the acquisition, transport, and deposition of metals in real hydrothermal systems that produced base metal ore deposits. Water-rock reactions that determine pH, together with total chloride and changes in temperature and fluid pressure, play significant roles in controlling the solubility of metals and determining where metals are fixed to form ore deposits. Deposition of metals in hydrothermal systems occurs where changes such as cooling, pH increase due to rock alteration, boiling, or fluid mixing cause the aqueous metal concentration to exceed saturation. Metal zoning results from deposition occurring at successive saturation surfaces. Zoning is not a reflection simply of relative solubility but of the manner of intersection of transport concentration paths with those surfaces. Saturation surfaces will tend to migrate outward and inward in prograde and retrograde time, respectively, controlled by either temperature or chemical variables. -from Authors

  11. MOISTURE-BUFFERING CHARACTERISTICS OF BUILDING MATERIALS

    Directory of Open Access Journals (Sweden)

    Young Cheol Choi

    2016-05-01

    Full Text Available The humidity level of indoor air is an important factor influencing the air quality and energy consumption of buildings, as well as the durability of building components. Indoor humidity levels depend on several factors, such as moisture sources, air flow, and the adsorption/desorption properties of materials. The moisture-buffering characteristics of building materials that are in contact with indoor air may help moderate the variations of indoor humidity, especially in the summer and winter. In this study, the moisture adsorption/desorption properties of building materials were investigated experimentally and numerically. These properties can be used to characterize the ability of building materials to exchange moisture with the indoor environment. This study indicates that a building material surface resistivity was the main factor creating variations of moisture buffering.

  12. Surface Water Protection by Productive Buffers

    DEFF Research Database (Denmark)

    Christen, Benjamin

    Vegetated riparian buffer zones are a widely recommended best management practice in agriculture for protecting surface and coastal waters from diffuse nutrient pollution. On the background of the EU funded research project NitroEurope (NEU; www.NitroEurope.eu), this study concentrates on the mit......Vegetated riparian buffer zones are a widely recommended best management practice in agriculture for protecting surface and coastal waters from diffuse nutrient pollution. On the background of the EU funded research project NitroEurope (NEU; www.NitroEurope.eu), this study concentrates...... viability and visualize the resulting landscape changes. For the Danish NEU landscape, a detailed plan of implementation options is presented, taking into account catchment morphology and hydrology, land use and drainage, access conditions, land ownership structure and land owner profiles. Different...

  13. MONITORING OF CONSTRUCTION PROJECT THROUGH BUFFER MANAGEMENT

    OpenAIRE

    Ms. Arti Bhan*1 & Prof. Ashish P. Waghmare2

    2017-01-01

    Critical Chain Project Management is an effective method over Critical Path Method (CPM) for scheduling and monitoring the progress of a project. CPM leads to ineffective scheduling due to overestimation of duration and increases the overall project duration. The task estimates in CPM are based on guess work whereas CCPM reduces the duration of task to 50% to that of its original duration as uses the remaining 50% duration as buffer to protect the activity against delays. Also the availabilit...

  14. Nuclear Calcium Buffering Capacity Shapes Neuronal Architecture*

    Science.gov (United States)

    Mauceri, Daniela; Hagenston, Anna M.; Schramm, Kathrin; Weiss, Ursula; Bading, Hilmar

    2015-01-01

    Calcium-binding proteins (CaBPs) such as parvalbumin are part of the cellular calcium buffering system that determines intracellular calcium diffusion and influences the spatiotemporal dynamics of calcium signals. In neurons, CaBPs are primarily localized to the cytosol and function, for example, in nerve terminals in short-term synaptic plasticity. However, CaBPs are also expressed in the cell nucleus, suggesting that they modulate nuclear calcium signals, which are key regulators of neuronal gene expression. Here we show that the calcium buffering capacity of the cell nucleus in mouse hippocampal neurons regulates neuronal architecture by modulating the expression levels of VEGFD and the complement factor C1q-c, two nuclear calcium-regulated genes that control dendrite geometry and spine density, respectively. Increasing the levels of nuclear calcium buffers by means of expression of a nuclearly targeted form of parvalbumin fused to mCherry (PV.NLS-mC) led to a reduction in VEGFD expression and, as a result, to a decrease in total dendritic length and complexity. In contrast, mRNA levels of the synapse pruning factor C1q-c were increased in neurons expressing PV.NLS-mC, causing a reduction in the density and size of dendritic spines. Our results establish a close link between nuclear calcium buffering capacity and the transcription of genes that determine neuronal structure. They suggest that the development of cognitive deficits observed in neurological conditions associated with CaBP deregulation may reflect the loss of necessary structural features of dendrites and spines. PMID:26231212

  15. Microbial activity in bentonite buffers. Literature study

    Energy Technology Data Exchange (ETDEWEB)

    Ratto, M.; Itavaara, M.

    2012-07-01

    The proposed disposal concept for high-level radioactive wastes involves storing the wastes underground in copper-iron containers embedded in buffer material of compacted bentonite. Hydrogen sulphide production by sulphate-reducing prokaryotes is a potential mechanism that could cause corrosion of waste containers in repository conditions. The prevailing conditions in compacted bentonite buffer will be harsh. The swelling pressure is 7-8 MPa, the amount of free water is low and the average pore and pore throat diameters are small. This literature study aims to assess the potential of microbial activity in bentonite buffers. Literature on the environmental limits of microbial life in extreme conditions and the occurrence of sulphatereducing prokaryotes in extreme environments is reviewed briefly and the results of published studies characterizing microbes and microbial processes in repository conditions or in relevant subsurface environments are presented. The presence of bacteria, including SRBs, has been confirmed in deep groundwater and bentonite-based materials. Sulphate reducers have been detected in various high-pressure environments, and sulphate-reduction based on hydrogen as an energy source is considered a major microbial process in deep subsurface environments. In bentonite, microbial activity is strongly suppressed, mainly due to the low amount of free water and small pores, which limit the transport of microbes and nutrients. Spore-forming bacteria have been shown to survive in compacted bentonite as dormant spores, and they are able to resume a metabolically active state after decompaction. Thus, microbial sulphide production may increase in repository conditions if the dry density of the bentonite buffer is locally reduced. (orig.)

  16. Methyl Bromide Commodity Fumigation Buffer Zone Lookup Tables

    Science.gov (United States)

    Product labels for methyl bromide used in commodity and structural fumigation include requirements for buffer zones around treated areas. The information on this page will allow you to find the appropriate buffer zone for your planned application.

  17. Buffer-free production of gamma-aminobutyric acid using an engineered glutamate decarboxylase from Escherichia coli.

    Science.gov (United States)

    Kang, Taek Jin; Ho, Ngoc Anh Thu; Pack, Seung Pil

    2013-08-15

    Escherichia coli glutamate decarboxylase (GAD) converts glutamate into γ-aminobutyric acid (GABA) through decarboxylation using proton as a co-substrate. Since GAD is active only at acidic conditions even though pH increases as the reaction proceeds, the conventional practice of using this enzyme involved the use of relatively high concentration of buffers, which might complicate the downstream purification steps. Here we show by simulation and experiments that the free acid substrate, glutamic acid, rather than its monosodium salt can act as a substrate and buffer at the same time. This yielded the buffer- and salt-free synthesis of GABA conveniently in a batch mode. Furthermore, we engineered GAD to hyper active ones by extending or reducing the length of the enzyme by just one residue at its C-terminus. Through the buffer-free reaction with engineered GAD, we could synthesize 1M GABA in 3h, which can be translated into a space-time yield of 34.3g/L/h. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. Complexation of buffer constituents with neutral complexation agents: part I. Impact on common buffer properties.

    Science.gov (United States)

    Riesová, Martina; Svobodová, Jana; Tošner, Zdeněk; Beneš, Martin; Tesařová, Eva; Gaš, Bohuslav

    2013-09-17

    The complexation of buffer constituents with the complexation agent present in the solution can very significantly influence the buffer properties, such as pH, ionic strength, or conductivity. These parameters are often crucial for selection of the separation conditions in capillary electrophoresis or high-pressure liquid chromatography (HPLC) and can significantly affect results of separation, particularly for capillary electrophoresis as shown in Part II of this paper series (Beneš, M.; Riesová, M.; Svobodová, J.; Tesařová, E.; Dubský, P.; Gaš, B. Anal. Chem. 2013, DOI: 10.1021/ac401381d). In this paper, the impact of complexation of buffer constituents with a neutral complexation agent is demonstrated theoretically as well as experimentally for the model buffer system composed of benzoic acid/LiOH or common buffers (e.g., CHES/LiOH, TAPS/LiOH, Tricine/LiOH, MOPS/LiOH, MES/LiOH, and acetic acid/LiOH). Cyclodextrins as common chiral selectors were used as model complexation agents. We were not only able to demonstrate substantial changes of pH but also to predict the general complexation characteristics of selected compounds. Because of the zwitterion character of the common buffer constituents, their charged forms complex stronger with cyclodextrins than the neutral ones do. This was fully proven by NMR measurements. Additionally complexation constants of both forms of selected compounds were determined by NMR and affinity capillary electrophoresis with a very good agreement of obtained values. These data were advantageously used for the theoretical descriptions of variations in pH, depending on the composition and concentration of the buffer. Theoretical predictions were shown to be a useful tool for deriving some general rules and laws for complexing systems.

  19. Buffer transport mechanisms in intentionally carbon doped GaN heterojunction field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Uren, Michael J.; Cäsar, Markus; Kuball, Martin [Center for Device Thermography and Reliability, H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom); Gajda, Mark A. [NXP Semiconductors, Bramhall Moor Lane, Hazel Grove, Stockport SK7 5BJ (United Kingdom)

    2014-06-30

    Temperature dependent pulsed and ramped substrate bias measurements are used to develop a detailed understanding of the vertical carrier transport in the buffer layers in a carbon doped GaN power heterojunction field effect transistor. Carbon doped GaN and multiple layers of AlGaN alloy are used in these devices to deliver an insulating and strain relieved buffer with high breakdown voltage capability. However, understanding of the detailed physical mechanism for its operation is still lacking. At the lowest electric fields (<10 MV/m), charge redistribution within the C doped layer is shown to occur by hole conduction in the valence band with activation energy 0.86 eV. At higher fields, leakage between the two-dimensional electron gas and the buffer dominates occurring by a Poole-Frenkel mechanism with activation energy ∼0.65 eV, presumably along threading dislocations. At higher fields still, the strain relief buffer starts to conduct by a field dependent process. Balancing the onset of these leakage mechanisms is essential to allow the build-up of positive rather than negative space charge, and thus minimize bulk-related current-collapse in these devices.

  20. Method of producing an electronic unit having a polydimethylsiloxane substrate and circuit lines

    Science.gov (United States)

    Davidson, James Courtney [Livermore, CA; Krulevitch, Peter A [Pleasanton, CA; Maghribi, Mariam N [Livermore, CA; Benett, William J [Livermore, CA; Hamilton, Julie K [Tracy, CA; Tovar, Armando R [San Antonio, TX

    2012-06-19

    A system of metalization in an integrated polymer microsystem. A flexible polymer substrate is provided and conductive ink is applied to the substrate. In one embodiment the flexible polymer substrate is silicone. In another embodiment the flexible polymer substrate comprises poly(dimethylsiloxane).