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Experimental and theoretical studies of vibrational density of states in Fe3O4 single-crystalline thin films

Physical Review B 2005年第14期71卷 144301-144301页

作者： B. Handke A. Kozłowski K. Parliński J. Przewoźnik T. Ślęzak A. I. Chumakov L. Niesen Z. Kąkol J. Korecki Institute of Catalysis & Surface Chemistry Polish Academy of Sciences Kraków Poland Faculty of Physics & Applied Computer Science AGH University of Science and Technology Kraków Poland The Henryk Niewodniczański Institute of Nuclear Physics Polish Academy of Sciences Kraków Poland European Synchrotron Radiation Facility P.B. 200 F-38043 Grenoble France Nuclear Solid State Physics Material Science Center University of Groningen Nijenborg 4 9747 AG Groningen The Netherlands

This paper presents experimental and theoretical studies of lattice vibrations in a single-crystalline Fe3O4(001) thin film. The investigations were carried out in order to see how the lattice dynamics changes at the Verwey transition. Vibrational densities of states (DOS) were obtained from nuclear inelastic scattering (NIS) of synchrotron radiation in the temperature range 25 to 296 K, while theoretical DOS were calculated ab initio within density functional theory. Experimental phonon density of states shows good agreement with calculated DOS, reproducing both the general features of main line groups as well as the groups’ structure. This is also in qualitative accord with heat capacity data, provided that experimental DOS is augmented with that calculated for oxygen atoms. We have observed a gradual change in the NIS raw data as well as the relevant DOS while lowering the temperature. In particular, the main peak in the energy region 15–25 meV shows increasing splitting on cooling. The Lamb-Mössbauer factor calculated in the course of DOS evaluation shows a pronounced drop in the vicinity of the Verwey transition that may be partly connected to the observed abrupt lowering of the count rate at approximately 7 meV for T

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Design consideration and finite element modeling of MEMS cantilever for nano-biosensor applications

Design consideration and finite element modeling of MEMS can...

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IEEE Conference on Nanotechnology

作者： D. Klaitabtim A. Tuantranont Department of Applied Physics Faculty of Science King Mongkut's Institute of Technology Ladkrabang Bangkok Thailand Nanoelectronics and MEMS Laboratory National Electronics and Computer Technology Center Klong Luang Pathum Thani Thailand

This work has focused on the design and finite element modeling of a MEMS cantilever beam for biosensor applications. The stress induced on gold surface with polysilicon piezoresistive sensing is demonstrated. In principle, adsorption of biochemical species on a functionalized surface of the microfabricated cantilever will cause a surface stress and consequently the cantilever bending. The sensing mechanism relies on the piezoresistive properties of the polysilicon wire encapsulated in the beam. The beam is constructed and bending analysis is performed so that, the beam tip deflection could be predicted. The twelve independent beams were combined onto a single chip. The piezoresistor designs on the beams were varied, within certain constraints, so that the sensitivity of the sensing technique could be studied. The chip was laid out using Tanner L-edit and the design rules of the MUMPs process were followed. The device model was simulated using CoventorWareIM, a commercial finite element analysis (FEA) tool designed specifically for MEMS applications. Finally, the MEMS cantilever beam was operated and caused increment in tip deflection due to biochemical adsorption on the gold surface.

关键词： Finite element methods Micromechanical devices Piezoresistance Structural beams Stress Gold Biosensors Mechanical factors Wire Performance analysis

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Unions of perfect matchings in cubic graphs

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Electronic Notes in Discrete Mathematics 2005年第0期22卷 341-345页

作者： Kaiser, Tomáš Norine, Serguei Department of Mathematics Institute for Theoretical Computer Science (ITI) University of West Bohemia 306 14 Plzeň Univerzitní 8 Czech Republic Institute for Mathematics Technical University Berlin D-10623 Berlin Strasse des 17. Juni 136 Germany Department of Applied Mathematics Faculty of Mathematics and Physics Charles University 118 00 Prague Malostranske namesti 25 Czech Republic School of Mathematics Georgia Institute of Technology Atlanta GA 30332 United States

We show that any cubic bridgeless graph with m edges contains two perfect matchings that cover at least 3m/5 and three perfect matchings that cover at least 27m/35 of its edges. © 2005 Elsevier B.V. All rights re... 详细信息

关键词： Berge-Fulkerson's conjecture cubic graphs perfect matchings

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Distribution of fluctuations of switching field in Fe-rich wires under tensile stress

Distribution of fluctuations of switching field in Fe-rich w...

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International Conference on Magnetics (INTERMAG)

作者： P. Gawronski A.P. Zhukov J.M. Blanco J. Gonzalez K. Kulakowski Faculty of Physics and Applied Computer Science AGH University of Science and Technology Cracow Poland Departamento de Fisica Aplicada I Universidad del Pais Vasco. Plaza de Europa 1 San Sebastian Spain Departmento de Fisica Aplicada Escuela Universitaria Politecnica de Donostia Donostia-San-Sebastian Spain Departamento de Fisica de Materiales Universidad del Pais Vasco San Sebastian Spain

In this paper, the distribution of fluctuations of switching field H/sub s/ in Fe/sub 77.5/B/sub 15/Si/sub 7.5/ amorphous wires under tensile stress is studied. The spectrum of the fluctuations of H/sub s/ for the microwires with the diameter of 125 /spl mu/m is investigated. Two different mechanisms are involved in the switching process and these are domain wall pinning on metastable local defects and the magnetoelastic energy. Results show that the switching field distributions is strongly affected by the applied stress. In particular, the part of the spectrum which contains large fluctuations is strongly affected by the magnetoelastic anisotropy. On the other hand, applied stresses also affect the pair ordering mechanism related to the domain wall stabilization which gives rise to the additional energetic potential. As the stress increases, the maximal observed value of H/sub s/ increases as well, due to the positive magnetoelastic coupling constant. This means that applied stresses reinforce the switching process at lower fields.

关键词： Fluctuations Wires Tensile stress Amorphous magnetic materials Magnetic anisotropy Perpendicular magnetic anisotropy Magnetic domain walls Magnetic domains Iron Amorphous materials

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Flow-induced correlation effects within a linear chain in a polymer melt

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Physical Review E 2005年第5期72卷 051807-051807页

作者： R. Stepanyan J. J. M. Slot J. Molenaar M. Tchesnokov Department of Applied Physics University of Twente P.O. Box 217 7500AB Enschede The Netherlands Material Science Centre DSM Research P.O. Box 18 6160 MD Geleen The Netherlands Faculty of Mathematics and Computer Science Eindhoven University P.O. Box 513 5600 MB Eindhoven The Netherlands Department of Applied Mathematics University of Twente P.O. Box 217 7500AB Enschede The Netherlands

A framework for a consistent description of the flow-induced correlation effects within a linear polymer chain in a melt is proposed. The formalism shows how correlations between chain segments in the flow can be incorporated into a hierarchy of distribution functions for tangent vectors. The present model allows one to take into account all the major relaxation mechanisms. Special cases of the derived set of equations are shown to yield existing models and shed some light on the connection between them. Consequences of several assumptions widely used in the literature are analyzed within the developed framework.

关键词： CONVECTIVE CONSTRAINT RELEASE COX-MERZ RULE MICROSCOPIC THEORY MOLECULARTHEORY CONSTITUTIVE EQUATION ENTANGLED POLYMERS TUBE MODEL STRETCH REPTATION DYNAMICS

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Magnetic properties and spin polarization of Co2MnSi Heusler alloy thin films epitaxially grown on GaAs(001)

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Physical Review B 2005年第14期71卷 144416-144416页

作者： W. H. Wang M. Przybylski W. Kuch L. I. Chelaru J. Wang Y. F. Lu J. Barthel H. L. Meyerheim J. Kirschner Max-Planck-Institut für Mikrostrukturphysik Weinberg 2 06120 Halle Germany National Institute for Materials Science 1-2-1 Sengen Tsukuba Ibaraki 305-0047 Japan Solid State Physics Department Faculty of Physics and Applied Computer Science AGH University of Science and Technology Mickiewicza 30 30-059 Krakow Poland Institut für Experimentalphysik Freie Universität Berlin Arnimallee 14 14195 Berlin Germany Institut für Experimentelle Physik Universität Duisburg-Essen Universitätsstrasse 5 45117 Essen Germany Department of Physics and HKU-CAS Joint Lab on New Materials The University of Hong Kong Hong Kong China

Single-crystalline Co2MnSi Heusler alloy films have been grown on GaAs(001) substrates by pulsed laser deposition (PLD). The best crystallographic quality of the Co2MnSi films has been achieved after deposition at 450 K. The films exhibit in-plane uniaxial magnetic anisotropy with the easy axis of magnetization along the [1-10] direction superimposed with a fourfold anisotropy with the easy axis along ⟨110⟩. Spin-resolved photoemission measurements of the single-crystalline Co2MnSi films reveal a spin-resolved density of states that is in qualitative agreement with recent band structure calculations. The spin polarization of photoelectrons close to the Fermi level is found to be at most 12%, in contrast to the predicted half-metallic behavior. We suggest that these discrepancies may be attributed to a partial chemical disorder in the Co2MnSi lattice.

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Relative output factor measurements of a 5 mm diameter radiosurgical photon beam using polymer gel dosimetry

Relative output factor measurements of a 5 mm diameter radio...

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作者： Pappas, E. Petrokokkinos, L. Angelopoulos, A. Maris, T.G. Kozicki, M. Dalezios, I. Kouloulias, V. Nuclear and Particle Physics Section Physics Department University of Athens Ilisia 157 71 Athens Greece Medical Physics Department MRI Unit University Hospital of Heraklion 711 10 Stavrakia-Heraklion Crete Greece Faculty of Textile Engineering Technical University of Lodz Zeromskiego St 116 90-543 Lodz Poland Institute of Applied Radiation Chemistry Technical University of Lodz Wroblewskiego Street 15 93-590 Lodz Poland Department of Biomedical Engineering University General Hospital Attikon 1 Rimini Street 124 62 Chaidari Athens Greece Department of Electrical Engineering and Computer Science National Technical University of Athens 9 Hroon Polytechniou Street 157 73 Athens Greece Medical Physics Department Anticancer-Oncologic Hospital of Athens Saint Savvas 171 Alexandras Ave. 115 22 Athens Greece Faculty of Medicine University Hospital of Heraklion University of Crete 711 10 Stavrakia-Heraklion Crete Greece

Besides the fine spatial resolution inherent in polymer gel-magnetic resonance imaging (MRI) dosimetry, the method also features the potential for multiple measurements of varying sensitive volume in a single experiment by integrating results in MRI voxels of finite dimensions (i.e., in plane resolution by slice thickness). This work exploits this feature of polymer gel dosimetry to propose an experimental technique for relative output factor (OF) measurements of small radiosurgical beams. Two gel vials were irradiated with a 5 and 30 mm diameter 6 MV radiosurgery beam and MR scanned with the same slice thickness and three different in plane resolutions. Using this experimental data set, 5 mm OF measurements with the PinPoint ion chamber are simulated by integrating results over a sensitive volume equal to that of the chamber. Results are found in agreement within experimental uncertainties with actual PinPoint measurements verifying the validity of the proposed experimental procedure. The polymer gel data set is subsequently utilized for OF measurements of the 5 mm beam with varying sensitive volume to discuss the magnitude of detector volume averaging effects. Seeking to correct for volume averaging, results are extrapolated to zero sensitive volume yielding a 5 mm OF measurement of (0.665%). This result compares reasonably with corresponding ionometric and radiographic film measurements of this work and corresponding, limited, data in the literature. Overall, results suggest that polymer gel dosimetry coupled with the proposed experimental procedure helps overcome not only tissue-equivalence and beam perturbation implications but also volume averaging and positioning uncertainties which constitute the main drawback in small radiosurgical beam dosimetry. © 2005 American Association of Physicists in Medicine.

关键词： Dosimetry

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ϒ and Drell-Yan production in p-A collisions at 450 GeV incident energy

ϒ and Drell-Yan production in p-A collisions at 450 GeV inc...

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2005 International Europhysics Conference on High Energy physics, HEP 2005

作者： Cortese, Pietro Alessandro, B. Alexa, C. Arnaldi, R. Atayan, M. Beolè, S. Boldea, V. Bordalo, P. Borges, G. Castanier, C. Castor, J. Chaurand, B. Cheynis, B. Chiavassa, E. Cicalò, C. Comets, M.P. Constantinescu, S. Cortese, P. De Falco, A. De Marco, N. Dellacasa, G. Devaux, A. Dita, S. Fargeix, J. Force, P. Gallio, M. Gerschel, C. Giubellino, P. Golubeva, M.B. Grigorian, A.A. Grigoryan, S. Guber, F.F. Guichard, A. Gulkanyan, H. Idzik, M. Jouan, D. Karavitcheva, T.L. Kurepin, A.B. Le Bornec, Y. Lourenço, C. Marzari-Chiesa, A. Masera, M. Masoni, A. Monteno, M. Musso, A. Petiau, P. Piccotti, A. Pizzi, J.R. Prino, F. Puddu, G. Quintans, C. Ramello, L. Ramos, S. Riccati, L. Santos, H. Saturnini, P. Scomparin, E. Serci, S. Shahoyan, R. Sigaudo, F. Sitta, M. Sonderegger, P. Tarrago, X. Topilskaya, N.S. Usai, G.L. Vercellin, E. Villatte, L. Willis, N. Wu, T. Dipartimento di Scienze e Tecnologie Avanzate Università del Piemonte Orientale Via Bellini 25/G Alessandria15100 Italy Universitá del Piemonte Orientale Alessandria and INFN- Torino Italy LPC Univ. Blaise Pascal CNRS-IN2P3 Aubière France IFA Bucharest Romania Università di Cagliari INFN Cagliari Italy CERN Geneva Switzerland LIP Lisbon Portugal INR Moscow Russia IPN Univ. de Paris-Sud and CNRS-IN2P3 Orsay France Laboratoire Leprince-Ringuet Ecole Polytechnique CNRS-IN2P3 Palaiseau France Università di Torino INFN Torino Italy IPN Univ. Claude Bernard Lyon-I CNRS-IN2P3 Villeurbanne France YerPhI Yerevan Armenia IST Universidade Técnica de Lisboa Lisbon Portugal AGH University of Science and Technology Faculty of Physics and Applied Computer Science Krakow Poland absence of YerPhI Yerevan Armenia

In the past few years the NA50 experiment carried out a comprehensive study of heavy quarkonia production, both in proton-nucleus and nucleus-nucleus collisions. In particular, data from p-A collisions have been collected in order to estimate the size of the absorption of quarkonia states in cold nuclear matter. Along with the studies on J/ψ and ψ, NA50 measured for the first time ϒ production at 450 GeV incident energy ( s 29☎ 1 GeV) on five nuclear targets (Be, Al, Cu, Ag and W) in the dimuon decay channel. We report here results on the cross section at mid-rapidity and the nuclear dependence of ϒ and Drell-Yan production. We analyzed as well the transverse momentum and rapidity distributions for the ϒ meson. The results are compared with previous measurements and with the predictions of theoretical models.

关键词： Germanium alloys

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Image Acquisition and Processing Using a PC Cluster toward Real-Time Solar Image Improvement

Image Acquisition and Processing Using a PC Cluster toward R...

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20th Congress of the International Commission for Optics

作者： Noriaki Miura Naoki Kodama Hiroshi Ohkama Hideaki Odagiri Naoshi Baba Hiroshi Kita Reizaburou Kitai Satoru Ueno Kiyoshi Ichimoto Takashi Sakurai Kitami Institute of Technology Department of Computer Sciences 165 Koen-cho Kitami 090-8507 Japan. Kitami Institute of Technology Department of Computer Sciences 165 Koen-cho Kitami 090-8507 Japan. Muroran Institute of Technology Department of Electrical and Electric engineering 27-1 Mizumoto-cho Muroran 050-8585 Japan. Muroran Institute of Technology Department of Electrical and Electric engineering 27-1 Mizumoto-cho Muroran 050-8585 Japan. Hokkaido University Department of Applied Physics Faculty of Engineering Sapporo 060-8628 Japan. Hokkaido University Department of Applied Physics Faculty of Engineering Sapporo 060-8628 Japan. Hida Observatory School of Science Kyoto University Kamitakara Takayama 506-1314 Japan. Hida Observatory School of Science Kyoto University Kamitakara Takayama 506-1314 Japan. National Astronomical Observatory 2-21-1 Ohsawa Mitaka 181-8588 Japan. National Astronomical Observatory 2-21-1 Ohsawa Mitaka 181-8588 Japan.

This paper describes a PC-cluster-based observation system for improving the angular resolution of solar images. The system consists of two equipments separately working: one equipment realizes automa

关键词： Solar image improvement, blind deconvolution, superresolution, PC cluster

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Development of QTAT online electronic circuit patterning system

Development of QTAT online electronic circuit patterning sys...

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作者： Wakasugi, Katsuhiko Wakimoto, Satoshi Akamichi, Takayuki Nakada, Akira Kubota, Hiroshi Inokuchi, Tsuneo Suzuki, Shinji Aikawa, Sou Kosaka, Kouji Nakamura, Kazumitsu Morimoto, Tatsuo IEEE Graduate School of Science and Technology Kumamoto University Kumamoto 860-8555 Japan Kumamoto Technology Center Sony Semiconductor Kyushu Corporation Kumamoto 869-1102 Japan Ushio Inc. Yokohama 225-0002 Japan Tecnos Co. Ltd. Nara 630-8113 Japan Kumamoto Technology Inc. Kumamoto 861-2202 Japan Kumamoto Technology and Industry Foundation Kumamoto 861-2202 Japan New Industry Creation Hatchery Center Tohoku University Sendai 980-8579 Japan Japan Society of Applied Physics Institute of Electronics Information and Communication Engineering Department of Electrical and Computer Engineering Faculty of Engineering Kumamoto University Graduate School of Science and Technology Kumamoto University Shock Wave and Condensed Matter Research Center Kumamoto University Sony Semiconductor Kyushu Corporation Kagoshima Japan Sony Semiconductor Kyushu Corporation Kumamoto Technology Center Kumamoto Japan Department of Electronic Engineering Tokyo University of Agriculture and Technology Tokyo Tecnos Co. Ltd. Nara Japan Tokyo Technology Co. Ltd. Tokyo Japan Kumamoto Technology Co. Ltd. Kumamoto Japan Japan Society of Precision Engineering Kumamoto Technology and Industry Foundation Kumamoto Japan American Vacuum Society New Industry Creation Hatchery Center Tohoku University

An arbitrary pattern exposure system has been developed by employing a liquid crystal display (LCD) with 1600 × 1200 pixels for the formation of projection images in place of a conventional reticle. The minimum pattern size becomes 11.5 μm, which corresponds to the aperture size of each pixel on the LCD. For the purpose of quick turnaround time (TAT), the exposure system was directly connected to the circuit design system with the transmission control protocol/internet protocol network. From the experimental results on patterning of a typical electronic circuit data with the area of 46 × 46 mm, it was confirmed that the TAT from the output of design data to the finish of the exposure becomes less than 28 min. By using this system, reduction of the production cost in the printed wiring boards fabrication is expected. © 2005 IEEE.

关键词： Online systems

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