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

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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Light scattering by white-emitting CdSe nanocrystals and traditional YAG:Ce3+ phosphor particles

Light scattering by white-emitting CdSe nanocrystals and tra...

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2008 MRS Fall Meeting

作者： Gosnell, Jonathan D. Weiss, Sharon M. Interdisciplinary Graduate Program in Materials Science Vanderbilt University Station B 350106 Nashville TN 37235 United States Department of Electrical Engineering and Computer Science Vanderbilt University Station B 351824 Nashville TN 37235 United States

ISBN: (纸本)9781615677740

In order for solid state lighting technology to become a mainstream technology, one of the major challenges to overcome is increasing the efficiency of these devices while maintaining a proper color balance. A significant source of efficiency loss in commercial phosphor-based white light-emitting diodes (LEDs) is light scattering off large, micron-sized phosphor particles. The use of recently reported single-size CdSe white-light nanocrystals in place of traditional phosphors, such as YAG:Ce3+, could lead to lower scattering losses and higher device efficiencies as a result of the extremely small CdSe core diameter of approximately 1.5 nm. This work theoretically and experimentally investigates the absorption, scattering, and extinction coefficients and cross sections of CdSe white-light nanocrystals in comparison to YAG:Ce3+ phosphor particles. Calculations were performed based on the Rayleigh approximation and Mie theory of scattering. Experiments were carried out using thin films of encapsulated nanocrystals. by measuring the absorbance and thickness of the films, in addition to the concentration of the nanocrystals, extinction coefficients and cross sections were determined using the beer-Lambert law. A reasonable agreement was obtained between theoretical and experimental data showing that the size of the particle has a significant impact on the extinction, absorption, and scattering properties of thin films. The considerably reduced scattering from the nanocrystals compared to traditional phosphors, along with their inherent high quality white light emission, makes them a promising candidate for future solid state lighting applications. © 2009 materials Research Society.

关键词： Cadmium compounds

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Microstructural development of porous β-Si3N4 ceramics prepared by pressureless-sintering compositions in the Si-Re-O-N quaternary systems (Re=La, Nd, Sm, Y, Yb)

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31st International Conference on Advanced Ceramics and Composites

作者： Quinlan, Mervin Heard, D. Plucknett, Kevin P. Garrido, Liliana Genova, Luis Materials Engineering Program Department of Process Engineering and Applied Science Dalhousie University 1360 Barrington Street Halifax NS B3J 1Z1 Canada M.B. Gonnet. Pcia De Buenos Aires Argentina IPEN Instituto de Pesquisas Energéticas e Nucleares CCTM Centro de Ciência e Technologia de Materiais Cidade Universitária Travessa R 400 05508-900 São Paulo Brazil

ISBN: (纸本)9780470196403

It has recently been demonstrated that porous β-Si3N 4 can be engineered to provide similar mechanical properties to dense β-Si3N4, with the additional benefits of reduced mass. Porous p-Si3N4 applications could potentially include filtration media, thermal shock resistant components and high-strength, lightweight structural components. Prior work in Japan has shown that flexural strengths exceeding 1 GPa can be achieved by tailoring the microstructure of the β-Si3N4 grains, such that moderately high aspect ratios are obtained after sintering (up to 10:1) with considerable anisotropic grain alignment, while maintaining porosity levels of ∼10-15 %. In the present study, β-Si3N4 ceramics containing higher porosity levels are generated via pressureless sintering in a nitrogen atmosphere, with the addition of single rare earth oxide sintering aids. The oxide additives have been chosen from both the lanthanide (La, Nd, Sm, Yb) and Group IIIb (Y) elements. In each case, the compositions were milled for 24 hours, cold isostatically pressed and then sintered in nitrogen (0.1 MPa) at temperatures ranging from 1500 to 1750°C. Post sinter microstructural characterization was performed using scanning electron microscopy and x-ray diffraction. It is noted that densification and phase transformation kinetics are both strongly influenced by the oxide chosen.

关键词： X ray diffraction

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Compositional design of porous β-Si3N4 prepared by pressureless-sintering compositions in the Si-Y-Mg-(Ca)-O-N system

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31st International Conference on Advanced Ceramics and Composites

作者： Quinlan, Mervin Plucknett, Kevin P. Garrido, Liliana Genova, Luis Materials Engineering Program Department of Process Engineering and Applied Science Dalhousie University 1360 Barrington Street Halifax NS B3J 1Z1 Canada M.B. Gonnet. Peia. De Buenos Aires Argentina IPEN Instituto de Pesquisas Energéticas e Nucleares CCTM Centro de Ciência e Technologia de Materiais Cidade Universitária Travessa R 400 05508-900 São Paulo Brazil

ISBN: (纸本)9780470196403

Porous β-Si3N4 can be microstructurally engineered to provide similar mechanical properties to dense β-Si 3N4 with the additional benefits of reduced mass. However, while flexural strengths exceeding 1 GPa can be achieved by tailoring the microstructure of the material, through alignment of anisotropic β-Si 3N4 grains, the porosity levels of such materials are still relatively low (3N4 structure (ideally 20-40 vol. % porosity) with high grain aspect ratios (i.e. >10:1). This approach makes use of a low volume fraction of multiple sintering aids, where each additive plays one or more roles in the sintering behavior of Si3N4 (i.e. densification aid, transformation aid and/or whisker growth aid). Compositions are based on various ratios of Y2O3:MgO, both with and without CaO additions. Sintering has been conducted in a nitrogen atmosphere (0.1 MPa) between 1400 and 1700°C. The effects of processing parameters (e.g. composition, sintering temperature and time) will be discussed, paying particular attention to microstructure development, including both the densification behavior and α- to β-Si3N4 transformation kinetics.

关键词： Silicon compounds

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Patterning Colloidal Films via Evaporative Lithography

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Physical Review Letters 2007年第14期98卷 148301-148301页

作者： Daniel J. Harris Hua Hu Jacinta C. Conrad Jennifer A. Lewis Department of Materials Science and Engineering and Frederick Seitz Materials Research Laboratory University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA Corporate Engineering Technical Lab The Procter and Gamble Company West Chester Ohio 45069 USA INEST Group Postgraduate Program Philip Morris USA Richmond Virginia 23234 USA

We investigate evaporative lithography as a route for patterning colloidal films. Films are dried beneath a mask that induces periodic variations between regions of free and hindered evaporation. Direct imaging reveals that particles segregate laterally within the film, as fluid and entrained particles migrate towards regions of higher evaporative flux. The films exhibit remarkable pattern formation that can be regulated by tuning the initial suspension composition, separation distance between the mask and underlying film, and mask geometry.

关键词： Liquid films

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Fatigue properties of high pressure die-cast magnesium AM60b alloy

Fatigue properties of high pressure die-cast magnesium AM60B...

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2007 World Congress

作者： Lu, Y. Taheri, F. Gharghouri, M. Materials Engineering Program Department of Process Engineering and Applied Science Dalhousie University Halifax NS B3J 2X4 Canada National Research Council Canada Canadian Neutron Beam Centre Chalk River Laboratories Chalk River ON K0J 1J0 Canada Department of Civil Engineering Dalhousie University 1360 Barrington Street Halifax NS B3J 1Z1 Canada

Magnesium castings are experiencing increased use in the transportation industry because of their high strength to weight ratio, high stiffness, and excellent castability. The casting characteristics allow complicated shapes to be cast to close tolerances with high reproducibility. As the use of magnesium castings increases, the need for research on this alloy is becomes more prevalent. Indeed, little research has been performed on magnesium alloys compared to aluminum castings. In the present study, the influence of the microstructure in a high pressure die casting AM60b magnesium auto component is investigated. Fatigue samples were removed from the component. Staircase fatigue testing was conducted first and the fracture surfaces were then examined with the scanning electron microscope. It was found that the majority of fatigue cracks initiated from sub-surface voids underneath machined surfaces, not the cast skins. Machining a specimen out of a casting causes internal voids to become sub-surface voids, which in turn causes premature fracture. In the region which is close to the fracture initiation site, extremely flat areas covered with fine fatigue striations can be easily observed. However, numerous randomly oriented serrated surfaces, indicative of rough fatigue crack growth were found near the regions farther away from the initiation site. Finally, the final fracture zone is characterized by a high level of porosity and dimples surrounding second phase particles. Copyright © 2007 SAE International.

关键词： Microstructure

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