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Preparation, characterization, and antibacterial activity of γ-irradiated silver nanoparticles in aqueous gelatin

International Journal of Minerals,Metallurgy and materials 2013年第4期20卷 403-409页

作者： Majid Darroudi Mansor B. Ahmad Mohammad Hakimi Reza Zamiri Ali Khorsand Zak Hasan Ali Hosseini Mohsen Zargar Department of Modern Sciences and Technologies School of Medicine Mashhad University of Medical Sciences Department of Chemistry Faculty of Science Universiti Putra Malaysia Chemistry Department Payame Noor University Department of Materials Engineering and Ceramic CICECO University of Aveiro Electroceramics and Materials Lab. Physics Department Faculty of Science Ferdowsi University of Mashhad Faculty of Science Qom Branch Islamic Azad University

Colloidal silver nanoparticles （Ag-NPs） were obtained through γ-irradiation of aqueous solutions containing AgNO3 and gelatin as a silver source and stabilizer, respectively. The absorbed dose of γ-irradiation influences the particle diameter of the Ag-NPs, as evidenced from surface plasmon resonance （SPR） and transmission electron microscopy （TEM） images. When the γ-irradiation dose was increased （from 2 to 50 kGy）, the mean particle size was decreased continuously as a result of γ-induced Ag-NPs fragmentation. The antibacterial properties of the Ag-NPs were tested against Methicillinresistant Staphylococcus aureus （MRSA）（Gram-positive） and Pseudomonas aeruginosa （P.a）（Gram-negative） bacteria. This approach reveals that the γ-irradiation-mediated method is a promising simple route for synthesizing highly stable Ag-NPs in aqueous solutions with good antibacterial properties for different applications.

关键词： silver nanoparticles silver nitrate gelatin gamma rays irradiation bacteria

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A new modulated structure in α-Fe_2O_3 nanowires

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Chinese Physics B 2013年第10期22卷 512-515页

作者：蔡鎔声商蕾刘雪华王乙潜袁露周光文 The Cultivation Base for State Key Laboratory Qingdao University Laboratory of Advanced Materials and Electron Microscopy Institute of PhysicsChinese Academy of Sciences Department of Mechanical Engineering & Multidisciplinary Program in Materials Science and Engineering State University of New York

A new modulated structure consisting of periodic （1120） stacking faults （SFs） in the α-Fe2O3 nanowires （NWs） formed by the thermal oxidation of Fe foils is reported, using a combination of high-resolution transmission electron microscopy （HRTEM） observations and HRTEM image simulations. The periodicity of the modulated structure is 1.53 nm, which is ten times （3500） interplanar spacing and can be described by a shift of every ten （3500） planes with 1/2 the interplanar spacing of the （1120） plane. An atomic model for the Fe203 structure is proposed to simulate the modulated structure. HRTEM simulation results confirm that the modulated structure in α-Fe2O3 NWs is caused by SFs.

关键词： crystal structure nanocrystalline materials electron microscopy simulation and modeling

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Magnesium vapor reduction of structured silica for lithium ion battery applications

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Nordic Journal of Linguistics 2014年第1期1643卷 1-6页

作者： Cook, Rob Schrandt, Matthew Kolla, Praveen Rhine, Wendell Koodali, Ranjit Smirnova, Alevtina Zyvex Technologies Rapid City 57701 SD United States Materials Engineering and Science Program South Dakota School of Mines and Technology Rapid City 57701 SD United States Aspen Aerogels Northborough 01532 MA United States University of South Dakota Vermillion 57069 SD United States Department of Chemistry and Applied Biological Sciences South Dakota School of Mines and Technology Rapid City 57701 SD United States

Three types of silica materials with different morphology, specifically SiO2 hollow microspheres, mesoporous silica, and silica aerogel were tested as potential precursors for synthesis of silicon nano-and meso-structures that resemble the original morphology of the precursors. In the optimized magnesium thermal reduction process, magnesium vapor was delivered to silica surface through a stainless steel mesh placed on top of a zirconia boat filled with silica precursor. This approach allowed for better control of silicon nanostructure formation by minimizing reaction by-products that can affect performance of lithium ion battery anode. Material morphological properties of the reduced silica precursors are discussed in terms of X-ray diffraction, BET, BJH pore size distribution, Raman spectroscopy, and TGA. © 2014 materials Research Society.

关键词： Li Mg Si

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Magnesium vapor reduction of structured silica for lithium ion battery applications

Magnesium vapor reduction of structured silica for lithium i...

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2013 MRS Fall Meeting

作者： Cook, Rob Schrandt, Matthew Kolla, Praveen Rhine, Wendell Koodali, Ranjit Smirnova, Alevtina Zyvex Technologies Rapid City SD 57701 United States Materials Engineering and Science Program South Dakota School of Mines and Technology Rapid City SD 57701 United States Aspen Aerogels Northborough MA 01532 United States University of South Dakota Vermillion SD 57069 United States Department of Chemistry and Applied Biological Sciences South Dakota School of Mines and Technology Rapid City SD 57701 United States

Three types of silica materials with different morphology, specifically SiO2 hollow microspheres, mesoporous silica, and silica aerogel were tested as potential precursors for synthesis of silicon nano- and meso-structures that resemble the original morphology of the precursors. In the optimized magnesium thermal reduction process, magnesium vapor was delivered to silica surface through a stainless steel mesh placed on top of a zirconia boat filled with silica precursor. This approach allowed for better control of silicon nanostructure formation by minimizing reaction by-products that can affect performance of lithium ion battery anode. Material morphological properties of the reduced silica precursors are discussed in terms of X-ray diffraction, BET, BJH pore size distribution, Raman spectroscopy, and TGA. Copyright © materials Research Society 2014.

关键词： Magnesium

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Existence of a Thermodynamic Spin-Glass Phase in the Zero-Concentration Limit of Anisotropic Dipolar Systems

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Physical Review X 2014年第4期4卷 041016-041016页

作者： Juan Carlos Andresen Helmut G. Katzgraber Vadim Oganesyan Moshe Schechter Theoretische Physik ETH Zurich CH-8093 Zurich Switzerland Department of Theoretical Physics Royal Institute of Technology SE-106 91 Stockholm Sweden Department of Physics and Astronomy Texas A&M University College Station Texas 77843-4242 USA Materials Science and Engineering Program Texas A&M University College Station Texas 77843 USA Santa Fe Institute 1399 Hyde Park Road Santa Fe New Mexico 87501 USA Department of Engineering Science and Physics College of Staten Island CUNY Staten Island New York 10314 USA Initiative for the Theoretical Sciences The Graduate Center CUNY New York New York 10016 USA Department of Physics Ben Gurion University of the Negev Beer Sheva 84105 Israel

The nature of ordering in dilute dipolar interacting systems dates back to the work of Debye and is one of the most basic, oldest and as-of-yet unsettled problems in magnetism. While spin-glass order is readily observed in several RKKY-interacting systems, dipolar spin glasses are the subject of controversy and ongoing scrutiny, e.g., in LiHoxY1−xF4, a rare-earth randomly diluted uniaxial (Ising) dipolar system. In particular, it is unclear if the spin-glass phase in these paradigmatic materials persists in the limit of zero concentration or not. We study an effective model of LiHoxY1−xF4 using large-scale Monte Carlo simulations that combine parallel tempering with a special cluster algorithm tailored to overcome the numerical difficulties that occur at extreme dilutions. We find a paramagnetic to spin-glass phase transition for all Ho+ ion concentrations down to the smallest concentration numerically accessible, 0.1%, and including Ho+ ion concentrations that coincide with those studied experimentally up to 16.7%. Our results suggest that randomly diluted dipolar Ising systems have a spin-glass phase in the limit of vanishing dipole concentration, with a critical temperature vanishing linearly with concentration. The agreement of our results with mean-field theory testifies to the irrelevance of fluctuations in interactions strengths, albeit being strong at small concentrations, to the nature of the low-temperature phase and the functional form of the critical temperature of dilute anisotropic dipolar systems. Deviations from linearity in experimental results at the lowest concentrations are discussed.

关键词： Computational physics Condensed matter physics Magnetism

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Degradation and deformation of carbon phenolic ablator in elevated temperature processes 19

Degradation and deformation of carbon phenolic ablator in el...

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19th International Conference on Composite materials, ICCM 2013

作者： Fukuda, K. Kubota, Y. Hatta, H. Kogo, Y. Hirai, K. Krenkel, W. Langhof, N. Department of Materials Science and Technology Tokyo University of Science Noda Japan Department of Space and Astronautical Science School of Physical Sciences Graduate University for Advanced Studies Sagamihara Japan Institute of Space and Astronautical Science Japan Aerospace Exploration Agency Sagamihara Japan Technologies Development Department IHI Aerospace Co. Ltd. Tomioka Japan Ceramic Materials Engineering University of Bayreuth Bayreuth Germany

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Hybrid materials: Strongly‐Coupled Freestanding Hybrid Films of Graphene and Layered Titanate Nanosheets: An Effective Way to Tailor the Physicochemical and Antibacterial Properties of Graphene Film (Adv. Funct. Mater. 16/2014)

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Advanced Functional materials 2014年第16期24卷

作者： In Young Kim Suhye Park Hyunseok Kim Sungsu Park Rodney S. Ruoff Seong‐Ju Hwang Center for Intelligent Nano‐Bio Materials (CINBM) Department of Chemistry and Nano Sciences Ewha Womans University Seoul 120–750 Korea Department of Mechanical Engineering and the Materials Science and Engineering Program The University of Texas at Austin Austin TX 78712 United States

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P-type and undoped InGaN across the entire alloy composition range

P-type and undoped InGaN across the entire alloy composition...

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10th Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2013

作者： Wang, Ke Araki, T. Yu, K.M. Katsuki, T. Mayer, M.A. Alarcon-Llado, E. Ager, J.W. Walukiewicz, W. Nanishi, Y. Department of Photonics Ritsumeikan University 1-1-1 Noji Higashi Kusatsu Shiga 525-8577 Japan Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley CA 94720 United States WCU Hybrid Materials Program Dept. of Materials Science and Engineering Seoul National University 151-744 Korea Republic of

We report a systematic study on undoped and Mg-doped InGaN grown by molecular beam epitaxy. Various experiments have been combined to demonstrate p-type InGaN across the entire alloy composition range. © 2013 IEEE.

ISBN: (纸本)9781467364751

关键词： Semiconductor alloys

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Selective surface functionalization at regions of high local curvature in graphene

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Chemical Communications 2013年第7期49卷 677-679页

作者： Wu, Qingzhi Wu, Yaping Hao, Yufeng Geng, Jianxin Charlton, Matthew Chen, Shanshan Ren, Yujie Ji, Hengxing Li, Huifeng Boukhvalov, Danil W. Piner, Richard D. Bielawski, Christopher W. Ruoff, Rodney S. State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Biomedical Materials and Engineering Center Wuhan University of Technology Wuhan 430070 China Department of Mechanical Engineering Department of Materials Science Department of Engineering Program The University of Texas at Austin Austin TX 78712 1 University Station C2200 United States Department of Chemistry and Biochemistry The University of Texas at Austin Austin TX 78712 1 University Station A1590 United States School of Computational Sciences Korea Institute for Advanced Study Seoul 130-722 South Korea ) School of Chemical and Biological Engineering Seoul National University Seoul 151-742 South Korea

Monolayer graphene was deposited on a Si wafer substrate decorated with SiO2 nanoparticles (NPs) and then exposed to aryl radicals that were generated in situ from their diazonium precursors. Using micro-Raman mapping, the aryl radicals were found to selectively react with the regions of graphene that covered the NPs. The enhanced chemical reactivity was attributed to the increased strain energy induced by the local mechanical deformation of the graphene. © The Royal Society of Chemistry.

关键词： GRAPHENE synthesis MONOMOLECULAR films SILICON wafers NANOPARTICLES -- Spectra DIAZONIUM compounds RAMAN effect

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Use of microseismicity for determining the structure of the fracture network of large-scale porous media

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Physical Review E 2013年第3期87卷 032152-032152页

作者： Tayeb A. Tafti Muhammad Sahimi Fred Aminzadeh Charles G. Sammis Mork Family Department of Chemical Engineering and Materials Science and the Petroleum Engineering Program University of Southern California Los Angeles California 90089-1211 USA Department of Earth Sciences University of Southern California Los Angeles California 90089 USA

We show that microseismic events—earthquakes with small magnitudes—can be fruitfully used to gain insight into the properties of the fracture network of large-scale porous media, such as oil, gas, and geothermal reservoirs. As an example, we analyze extensive data for the Geysers geothermal field in northeast California. Injection of cold water into the reservoir to produce steam leads to microseismic events. It is demonstrated that the analysis can also lead to insight into whether the fractures are of tectonic type or induced by injection of cold water. To demonstrate this we estimate, using the catalogue of the microseismic events, the fractal dimension Df of the spatial distribution of hypocenters of the events in three seismic clusters associated with the injection of cold water into the field, as well as the b values in the Gutenberg-Richter frequency-magnitude distribution. The fractal dimensions are all in a narrow range centered around Df≃2.57±0.06, comparable to the measured fractal dimension of fracture sets in the greywacke reservoir rock. For most cases the b values are about b≃1.3±0.1, consistent with the Aki relation, Df=2b. Both Df and b are significantly higher than those commonly observed for regional tectonic seismicity or aftershock sequences for which Df≈2 and b≈1 are typical. Our results do not imply that no tectonic triggering exists in the reservoir, but rather that the overpressure allows the activation of less favorably oriented fractures that produce an increase in both b and Df. The estimate Df≈2 for tectonic seismicity has been interpreted as indicating that most tectonic events occur on the subset of near-vertical faults—because they have lower normal stress—or that they occur on the backbone of the fracture and fault network, the multiply connected part of the network that enables finite shear strain. Our results lend support to the latter. The results that the entire fracture network, and not just its backbone, is active at the Geyser

关键词： Hydraulic fracturing

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