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Photoluminescence of bismuth Germanate Phosphors with a Silica-shell Structure

Physics Procedia 2012年 29卷 91-96页

作者： M.J. Oviedo J.K. Han O. Contreras Z.S. Macedo G.A. Hirata J. McKittrick Programa de Posgrado en F'sica de Materiales CICESE-UNAM carretera Ensenada-Tijuana No. 3918 Ensenada B.C. MŽxico University of California at San Diego Materials Science and Engineering Program La Jolla CA 92093-0418 Centro de Nanociencias y Nanotecnolog’a UNAM Ensenada B.C. MŽxico Departamento de F'sica Universidade Federal de Sergipe Sao Cristva SE Brazil University of California at San Diego Mechanical and Aerospace Engineering La Jolla CA 92093-0411

An intense bluish-white emitting phosphor bi 4 Ge 3 O 12 (bGO) was synthesized by tartaric acid-assisted solgel method and covered with a SiO 2 nanolayer by the sol-gel method. The cubic crystal structure of bGO was confirmed by X-ray diffraction. Transmission electron microscopy analysis revealed the particle size to be in the range of 6-20 nm. Under excitation with 4.3 eV photons the bGO powders showed a PL contribution centered at 2.43 eV that corresponds to the typical bGO luminescence associated with 3 P 1 à 1 S0 of bi 3+ electron transitions. Radioluminescence measurements showed the predominant emission centered at 2.43 eV due to the intra-ionic bi3+ transitions. The PL emission of the silica coated bGO nanoparticles presented a luminescence enhancement of more than 200% compared with the uncoated nanoparticles. This enhancement in photoluminescence is proposed to be related to the reflectivity (refractive index) between air-silica-bGO layers.

关键词： bismuth germanate sol-gel silica coating photoluminescence

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Substitution effect of (Mn, Ti) to the dielectric properties of barium-strontium hexaferrite for absorbing electromagnetic waves

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AIP Conference Proceedings 2011年第1期1454卷 282-285页

作者： Repi, V. Vekky R. Manaf, Azwar Postgraduate Program of Materials Science Faculty of Mathematics and Natural Science Universitas Indonesia Jakarta 10430 Jalan Salemba Raya 4 Indonesia Faculty of Engineering and Science Department of Engineering Physics Universitas Nasional Jakarta 12520 Indonesia

The objective of this work is to evaluate the ability of Mn-Ti substituted barium-strontium hexaferrite to absorb high frequency electromagnetic wave. To accomplish this objective, Mn-Ti substituted barium strontium hexaferrite of ba0.5Sr0.5Fe12-x(Mn0.5Ti0.5)x with x = 0.1, x=0.3, x=0.5 were prepared through mechanical alloying route. Phase identification of the material obtained from XRD pattern indicating that the material is single phase for all variations of x. Coercivity and the remanent obtained by analyzing the hysteresis curve. The lowest coercivity at x = 0.5 for 77.86 kA/m but also lower the remanent of 0.088 kA/m. Dielectric properties of the material traced by calculating the value of permittivity and permeability of the material that was obtained with the parameters of the scattering vector network analyzer (VNA) in the 8GHz to 12GHz range. © 2012 American Institute of Physics.

关键词： barium-strontium hexaferrite Electromagnetic wave absorber Mechanical alloying Permittivity and permeability

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Low Resistivity-Highly Transparent Zno:Ga Tco's Grown by Laser Ablation

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MRS Online Proceedings Library (OPL) 2011年第1期397卷 247-247页

作者： J. M. Siqueiros J.A. Díaz O. Contreras G.A. Hirata J. McKittrick Instituto de Física-UNAM Apdo. Postal 2681 Ensenada B.C. C.P. 22860 México. Dept. of Applied Mechanics and Engineering Sciences and Materials Science Program University of California San Diego La Jolla CA 92093-0411

Highly transparent with low electrical resistivity gallium-doped zinc oxide (ZnO:Ga) thin films were prepared on glass by Pulsed Laser Deposition at different substrate temperatures. ZnO:Ga evaporation targets were prepared by pressing and sintering powder materials obtained with a novel combustion synthesis *** excellent transmittance of more than 85% in the visible range and a low sheet resistance value as low as 13 Ω/sq. were measured on a 200 nm thickness film grown at Ts=300°C. From optical measurements we observed an increase in the ZnO:Ga bandgap when the substrate temperature is raised from 150°C to 300°C. With this, a remarkable improvement in the blue-green region transmittance is obtained.X-Ray diffraction patterns indicate that the films grow highly oriented in the basal plane direction (c-axis) of the hexagonal ZnO grains.

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Thermal conductivity of indium arsenide nanowires with wurtzite and zinc blende phases

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Physical Review b 2011年第20期83卷 205416-205416页

作者： Feng Zhou Arden L. Moore Jessica bolinsson Ann Persson Linus Fröberg Michael T. Pettes Huijun Kong Lew Rabenberg Philippe Caroff Derek A. Stewart Natalio Mingo Kimberly A. Dick Lars Samuelson Heiner Linke Li Shi Materials Science and Engineering Program The University of Texas at Austin Austin Texas 78712 USA Department of Mechanical Engineering The University of Texas at Austin Austin Texas 78712 USA Solid State Physics Lund University Box 118 S-22100 Lund Sweden Physics Department and Materials Science Institute University of Oregon Eugene Oregon 97403 USA Institut d’Electronique de Microélectronique et de Nanotechnologie UMR CNRS 8520 Avenue Poincaré B.P. 60069 F-59652 Villeneuve d’Ascq France Cornell Nanoscale Facility Cornell University Ithaca New York 14850 USA CEA LITEN F-38054 Grenoble France University of California at Santa Cruz Jack Baskin School of Engineering Santa Cruz California 95064 USA Polymer & Materials Chemistry Box 124 Lund University S-22100 Lund Sweden

The thermal conductivity of wurtzite and zinc blende indium arsenide nanowires was measured using a microfabricated device, with the crystal structure of each sample controlled during growth and determined by transmission electron microscopy. Nanowires of both phases showed a reduction of the thermal conductivity by a factor of 2 or more compared to values reported for zinc blende indium arsenide bulk crystals within the measured temperature range. Theoretical models were developed to analyze the measurement results and determine the effect of phase on phonon transport. branch-specific phonon dispersion data within the discretized first brillouin zone were calculated from first principles and used in numerical models of volumetric heat capacity and thermal conductivity. The combined results of the experimental and theoretical studies suggest that wurtzite indium arsenide possesses similar volumetric heat capacity, weighted average group velocity, weighted average phonon-phonon scattering mean free path, and anharmonic scattering-limited thermal conductivity as the zinc blende phase. Hence, we attribute the differing thermal conductivity values observed in the indium arsenide nanowires of different phases to differences in the surface scattering mean free paths between the nanowire samples.

关键词： THERMAL conductivity INDIUM arsenide NANOWIRES WURTZITE SPHALERITE MICROREACTORS ELECTRON microscopy

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Europium-doped Pyrochlores for Use as Thermographic Phosphors in Thermal barrier Coatings

Europium-doped Pyrochlores for Use as Thermographic Phosphor...

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作者： Desai, Saunak K. Hansel, Rachael A. Pitz, Robert W. Walker, D. Greg Department of Mechanical Engineering Vanderbilt University VU Station B 351592 Nashville TN 37235 United States Interdisciplinary Materials Science Program Vanderbilt University Nashville TN 37235 United States

ISBN: (纸本)9781600867392

Three europium-doped pyrochlores including La2Zr 2O7:Eu, La2Hf2O7:Eu, and Nd2Zr2O7:Eu were tested to determine their lifetimes as a function of temperature. These pyrochlores were examined to determine their suitability as thermographic phosphors, in systems that use these materials for thermal barrier coatings. Results show that La 2Hf2O7:Eu and La2Zr 2O7:Eu can be used to measure surface temperatures up to approximately 600° C and 800° C, respectively. However, Nd 2Zr2O7:Eu showed little propensity for use as a thermographic phosphor. Copyright © 2010 by the American Institute of Aeronautics and Astronautics, Inc.

关键词： Phosphors

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Spin injection/detection using an organic-based magnetic semiconductor (vol 9, pg 638, 2010)

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NATURE materials 2010年第9期9卷 638-642页

作者： Yoo, Jung-Woo Chen, Chia-Yi Jang, H. W. bark, C. W. Prigodin, V. N. Eom, C. b. Epstein, A. J. Department of Physics The Ohio State University Columbus Ohio 43210-1117 USAJung-Woo YooV. N. Prigodin &A. J. EpsteinDepartment of Chemistry The Ohio State University Columbus Ohio 43210-1173 USAJung-Woo Yoo &A. J. EpsteinChemical Physics Program The Ohio State University Columbus Ohio 43210-1106 USAChia-Yi ChenDepartment of Materials Science and Engineering University of Wisconsin–Madison Madison Wisconsin 53706-1595 USAH. W. JangC. W. Bark &C. B. Eom

An important component of spintronics devices is the magnetic electrode, which is usually made from an inorganic alloy. However, an organic-based spin polarizer is now demonstrated, opening new possibilities for devel... 详细信息

关键词： Subject terms:Electronic materials Molecular electronics Magnetic materials

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Tandem multimer expression of angiotensin I-converting enzyme inhibitory peptide in Escherichia coli

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biotechnology Journal 2009年第9期4卷 1345-1356页

作者： Fida, Hasan M. Kumada, Yoichi Terashima, Masaaki Katsuda, Tomohisa Katoh, Shigeo Department of Molecular Science and Material Engineering Graduate School of Science and Technology Faculty of Engineering Kobe Japan Department of Chemistry and Materials Technology Kyoto Institute of Technology Kyoto Japan Department of Biosphere Sciences School of Human Science Kobe College Nishinomiya Japan Department of Chemical Engineering Hanyang University 1271 Sa-3-dong Sangrok-gu Ansan 426-791 Korea Republic of Department of Process Engineering and Applied Science Food Science and Technology Program Dalhousie University 1360 Barrington Street Halifax NS B3J 2X4 Canada

It is common for small tandem peptide multimer genes to be indirectly inserted into expression vectors and fused with a protein tag. In this study, a multimer of the tandem angiotensin I-converting enzyme inhibitory peptide (ACE-IP) gene was directly transferred to a commercially available vector and the designed gene was expressed as a repeated peptide in Escherichia coli bL21(DE3)pLysS. The process further developed in our study was the construction of six-repeated ACE-IP synthetic genes and their direct insertion. Protein expression in inclusion bodies was confirmed by SDS-PAGE and Western blot. Acid hydrolysis of inclusion bodies produced single-unit peptides through cleavage of the aspartyl-prolyl bonds. This cleaved recombinant peptide (rACE-IP) was purified using immuno-affinity chromatography followed by reversed phase-HPLC. 105-115 mg of the lyophilized recombinant peptide was obtained from 1 L E. coli culture. In vitro biological activity of rACE-IP was indistinguishable from that of the natural peptide produced by hydrolysis in artificial gastric juice or by acidic hydrolysis. The rACE-IP prepared by recombinant DNA technology and solid-phase synthesis methods showed a similar IC50. This strategy could be used for the expression of important peptides, which have N-terminal proline (P) and C-terminal aspartic acid residues (D) for commercial applications, e.g. functional foods and drinks. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

关键词： Peptides

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Neural Electrodes: Interfacing Conducting Polymer Nanotubes with the Central Nervous System: Chronic Neural Recording using Poly(3,4‐ethylenedioxythiophene) Nanotubes (Adv. Mater. 37/2009)

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Advanced materials 2009年第37期21卷

作者： Mohammad Reza Abidian Kip A. Ludwig Timothy C. Marzullo David C. Martin Daryl R. Kipke Department of Biomedical Engineering The University of Michigan 1101 Beal Ave. Ann Arbor MI 48109 (USA) Department of Biomedical Engineering The University of Michigan Ann Arbor MI 48109 (USA) Neuroscience Program The University of Michigan Ann Arbor MI 48109 (USA) Department of Materials Science and Engineering Macromolecular Science and Engineering and Biomedical Engineering Ann Arbor MI 48109 (USA) Present Address: Karl W. Böer Professor and Chair Materials Science and Engineering The University of Delaware 201C DuPont Hall Newark DE 19716 (USA)

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Effect of Nitrogen Concentration on Nanodiamond Film Characteristics for Electrode Application

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ECS Transactions 2009年第21期19卷

作者： Supil Raina Xuan-Anh C. LeQuan Weng P. Kang J. L. Davidson Interdisciplinary Program in Materials Science Vanderbilt University 5617 Stevenson Center Nashville Tennessee 37235 Electrical Engineering Vanderbilt University 5617 Stevenson Center Nashville TN 37232 Vanderbilt University Box 1661-B Nashville TN 37235 Vanderbilt University

Microwave plasma chemical vapor deposition was used to fabricate nanodiamond films. Nitrogen incorporation was achieved by the introduction of N2 gas along with H2 and CH4 gases in the plasma. SEM studies revealed a change in the microstructure with increase in the N2 flow rate, transitioning from a 'ridge'-like surface morphology to a more 'cauliflower'-like structure. X-ray photoelectron spectroscopy (XPS) analysis showed a general decrease in the sp3 hybridized carbon content while the sp2 hybridized carbon content increased with N2 flow rate (up to 28.7%) after which it declines. Deconvolution of the C1s XPS spectra indicates incorporation of nitrogen and existence of carbon-nitrogen bonding. Raman spectroscopy shows diamond peak at 1332 cm-1 and the graphite peak, which increases in intensity and shifts towards lower wave number with increase in the N2 flow rate. A diffuse band at 1140 cm-1 indicates presence of a nanocrystalline phase in the films.

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Effect of Nitrogen Concentration on Nanodiamond Film Characteristics for Electrode Application

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ECS Meeting Abstracts 2009年第43期MA2009-01卷

作者： Supil Raina Weng P. Kang J. L. Davidson Xuan-Anh C. LeQuan Interdisciplinary Program in Materials Science Vanderbilt University 5617 Stevenson Center Nashville Tennessee 37235 Vanderbilt University Box 1661-B Nashville TN 37235 Vanderbilt University Electrical Engineering Vanderbilt University 5617 Stevenson Center Nashville TN 37232

Abstract not Available.

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