检索结果-内蒙古大学图书馆

International Symposium Semiconductor Device Research (ISDRS)

作者： D. Gu F. Naumann M. Petzold M. Zhu H. Baumgart Electrical Engineering The Applied Research Center Old Dominion University Newport News VA USA Fraunhofer Institute of Mechanics of Materials (IWM) Halle Germany Department of Applied Science College of William and Mary Williamsburg VA USA

The authors study the simplest but scientifically relevant case, where in the absence of capping layers or any other precautions, strain relaxation by film patterning and high temperature annealing can be observed. The thermal stability of bi-axial strain is maintained solely by a nonepitaxial bonded interface with the amorphous buried oxide in sSOI after patterning and subsequent high temperature annealing.

关键词： Capacitive sensors Silicon on insulator technology Raman scattering Spectroscopy Computer simulation Temperature Annealing Thermal stability Bonding Amorphous materials

来源：评论

学校读者我要写书评

暂无评论

Different stages of flame acceleration from slow burning to Chapman-Jouguet deflagration

引用

Physical Review E 2009年第3期80卷 036317-036317页

作者： Damir M. Valiev Vitaly Bychkov V’yacheslav Akkerman Lars-Erik Eriksson Department of Physics Umeå University S-901 87 Umeå Sweden Department of Materials Science and Engineering Royal Institute of Technology SE-10044 Stockholm Sweden Department of Mechanical and Aerospace Engineering Princeton University D323-A Engineering Quad. Princeton New Jersey 08544-5263 USA Department of Applied Mechanics Chalmers University of Technology 412 96 Göteborg Sweden

Numerical simulations of spontaneous flame acceleration are performed within the problem of flame transition to detonation in two-dimensional channels. The acceleration is studied in the extremely wide range of flame front velocity changing by 3 orders of magnitude during the process. Flame accelerates from realistically small initial velocity (with Mach number about 10−3) to supersonic speed in the reference frame of the tube walls. It is shown that flame acceleration undergoes three distinctive stages: (1) initial exponential acceleration in the quasi-isobaric regime, (2) almost linear increase in the flame speed to supersonic values, and (3) saturation to a stationary high-speed deflagration velocity. The saturation velocity of deflagration may be correlated with the Chapman-Jouguet deflagration speed. The acceleration develops according to the Shelkin mechanism. Results on the exponential flame acceleration agree well with previous theoretical and numerical studies. The saturation velocity is in line with previous experimental results. Transition of flame acceleration regime from the exponential to the linear one, and then to the constant velocity, happens because of gas compression both ahead and behind the flame front.

关键词： Acceleration

来源：评论

学校读者我要写书评

暂无评论

Mechanical stiffness and dissipation in ultrananocrystalline diamond microresonators

引用

Physical Review B 2009年第24期79卷 245403-245403页

作者： V. P. Adiga A. V. Sumant S. Suresh C. Gudeman O. Auciello J. A. Carlisle R. W. Carpick Department of Materials Science and Engineering University of Pennsylvania Philadelphia Pennsylvania 19104 USA Center for Nanoscale Materials Argonne National Laboratory Argonne Illinois 60439 USA Innovative Micro Technology Santa Barbara California 93117 USA Materials Science Division Argonne National Laboratory Argonne Illinois 60439 USA Advanced Diamond Technologies Romeoville Illinois 60446 USA Department of Mechanical Engineering and Applied Mechanics University of Pennsylvania Philadelphia Pennsylvania 19104 USA

We have characterized mechanical properties of ultrananocrystalline diamond (UNCD) thin films grown using the hot filament chemical vapor deposition (HFCVD) technique at 680 °C, significantly lower than the conventional growth temperature of ∼800 °C. The films have ∼4.3% sp2 content in the near-surface region as revealed by near edge x-ray absorption fine structure spectroscopy. The films, ∼1 μm thick, exhibit a net residual compressive stress of 370±1 MPa averaged over the entire 150 mm wafer. UNCD microcantilever resonator structures and overhanging ledges were fabricated using lithography, dry etching, and wet release techniques. Overhanging ledges of the films released from the substrate exhibited periodic undulations due to stress relaxation. This was used to determine a biaxial modulus of 838±2 GPa. Resonant excitation and ring-down measurements in the kHz frequency range of the microcantilevers were conducted under ultrahigh vacuum (UHV) conditions in a customized UHV atomic force microscope system to determine Young’s modulus as well as mechanical dissipation of cantilever structures at room temperature. Young’s modulus is found to be 790±30 GPa. Based on these measurements, Poisson’s ratio is estimated to be 0.057±0.038. The quality factors (Q) of these resonators ranged from 5000 to 16000. These Q values are lower than theoretically expected from the intrinsic properties of diamond. The results indicate that surface and bulk defects are the main contributors to the observed dissipation in UNCD resonators.

关键词： atomic force microscopy cantilevers chemical vapour deposition compressive strength defect states diamond EXAFS internal stresses lithography micromechanical resonators nanoelectromechanical devices nanostructured materials Poisson ratio Q-factor stress relaxation thin films XANES Young's modulus

来源：评论

学校读者我要写书评

暂无评论

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

引用

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

来源：评论

学校读者我要写书评

暂无评论

Development of 2.4-GHz film bulk acoustic wave filter for wireless communication

引用

Journal of Micro/Nanolithography, MEMS, and MOEMS 2009年第2期8卷

作者： Fang, Chi-Ming Pao, Shih-Yung Lee, Chi-Yuan Lu, Yi-Chang Chen, Pei-Yen Chin, Yung-Chung Chang, Pei-Zen National Taiwan University Institute of Applied Mechanics 1 Sec. 4 Roosevelt Road Taipei 106 Taiwan Yuan Ze University Department of Mechanical Engineering Fuel Cell Research Center 135 Yuan-Tung Road Chungli 320 Taoyuan Taiwan Asia Pacific Microsystems Inc. No. 2 R and D Road 6 Hsinchu Taiwan Chung-Shan Institute of Science and Technology Materials and Electro-Optics Research Division P.O. Box 90008-8-6 Lung-TanYuan 325 Taiwan TXC Corporation 4 Kung Yeh 6th Road Cheng City Tao Yuan 324 Taiwan

This research shows the realization of 2.4-GHz film bulk acoustic wave (FBAW) filters. The design, simulation, fabrication, measurement, and analysis of the film bulk acoustic wave resonator (FBAR) devices are covered, which is helpful for the manufacture of the FBAR devices. The simulation of the FBAR and RF circuitry can be integrated on a single platform. The fabrication of the FBAW filters is compatible with complementary metal-oxide semiconductors. This device can be used in 2.4-GHz bandpass filters, such as 802.11b/g and Bluetooth. In this research, the 2.4-GHz FBAW filters for wireless communication have been accomplished. The fabricated FBAW filters have insertion loss of -10 dB, return loss of -7 dB, and stopband rejection of -25 dB, central frequency of 2.485 GHz, bandwidth of 60 MHz, and size of 0.5 mm × 0.5 mm. © 2009 Society of Photo-Optical Instrumentation Engineers.

关键词： MEMS

来源：评论

学校读者我要写书评

暂无评论

Directional photoluminescence enhancement of organic emitters via surface plasmon coupling

引用

applied Physics Letters 2009年第10期94卷

作者： Nien, Shou-Yu Chiu, Nan-Fu Ho, Yu-Hsuan Lee, Jiun-Haw Lin, Chii-Wann Wu, Kuang-Chong Lee, Chih-Kung Lin, Jia-Rong Wei, Mao-Kuo Chiu, Tien-Lung Graduate Institute of Photonics and Optoelectronics National Taiwan University Taipei 10617 Taiwan Department of Electrical Engineering National Taiwan University Taipei 10617 Taiwan Institute of Biomedical Engineering National Taiwan University Taipei 10617 Taiwan Institute of Applied Mechanics National Taiwan University Taipei 10617 Taiwan Department of Materials Science and Engineering Institute of Opto-Electronic Engineering National Dong Hwa University Hualien 97401 Taiwan

In this paper, we had quantitatively investigated the photoluminescence of organic emitter on a Si substrate with periodically corrugated metal thin film experimentally and theoretically. Due to the plasmonic coupling by the metal gratings, 4.3 times and 1.7 times enhancements in optical intensities were observed at specified and full viewing angles at certain wavelengths, respectively. Good agreement of angular-frequency versus in-plane wavevector (ω-k) curves between experiments and calculations were obtained when varying organic materials, metal materials, and grating pitches. Two different metal materials were used, which show slight shift in ω-k curves due to the high sensitivity of the surface plasmon to the relative permittivity. © 2009 American Institute of Physics.

关键词： Surface plasmons

来源：评论

学校读者我要写书评

暂无评论

Ab initio study of the phase stability in paramagnetic duplex steel alloys

引用

Physical Review B 2009年第2期79卷 024108-024108页

作者： H. Pitkänen M. Alatalo A. Puisto M. Ropo K. Kokko M. P. J. Punkkinen P. Olsson B. Johansson S. Hertzman L. Vitos Department of Mathematics and Physics Lappeenranta University of Technology P.O. Box 20 FIN-53851 Lappeenranta Finland Department of Applied Physics Helsinki University of Technology P.O. Box 1100 FI-02015 HUT Espoo Finland Department of Physics and Astronomy University of Turku FIN-20014 Turku Finland Department of Information Technology Åbo Akademi Fin-20500 Turku Finland Department of Materials Science and Engineering Applied Materials Physics Royal Institute of Technology Stockholm SE-100 44 Sweden Department of Materials and Mechanics of Components EDF R&D F-77250 Moret-sur-Loing France Department of Physics and Materials Science Division for Materials Theory Uppsala University SE-75121 Uppsala Sweden Department of Materials Science and Engineering Outokumpu Stainless Research Foundation Royal Institute of Technology Stockholm SE-100 44 Sweden Research Institute for Solid State Physics and Optics P.O. Box 49 Budapest H-1525 Hungary

Duplex stainless steels have many superior properties compared to conventional steels, this being mainly due to their microstructure containing approximately equal amount of ferrite and austenite phases formed by iron, chromium (or Cr equivalent), and nickel (or Ni equivalent). Using computational methods based on first-principles theories, the phase stability of paramagnetic Fe1−c−nCrcNin alloys (0.12≤c≤0.32 and 0.04≤n≤0.32) at high temperatures (≳1000 K) is addressed. It is shown that the stabilization of the ferrite-austenite two-phase field in duplex steels is a result of complex interplay of several competing phenomena. Taking into account only the formation energies yields a complete phase separation, strongly overestimating the two-phase region. The formation energies are calculated to be lower for the austenite than for the ferrite, meaning that the configurational entropy has a more significant impact on the stability field of the austenitic phase. The magnetic and vibrational free energies have opposite effects on the phase stability. Namely, the magnetic entropy favors the ferrite phase, whereas the vibrational free energy stabilizes the austenite phase. Combining the formation energies with the magnetic, vibrational, and configurational free energies, a region of coexistence between the two phases is obtained, in line with former thermodynamic assessments as well as with experimental observations.

关键词： ab initio calculations free energy magnetic transitions paramagnetic materials phase diagrams steel

来源：评论

学校读者我要写书评

暂无评论

Novel Low-Temperature Behavior in Classical Many-Particle Systems

引用

Physical Review Letters 2009年第5期103卷 050602-050602页

作者： Robert D. Batten Frank H. Stillinger Salvatore Torquato Department of Chemical Engineering Princeton University Princeton New Jersey 08544 USA Department of Chemistry Princeton University Princeton New Jersey 08544 USA Princeton Materials Institute Program in Applied and Computational Mathematics Princeton Center for Theoretical Science Princeton University Princeton New Jersey 08544 USA School of Natural Sciences Institute for Advanced Study Princeton New Jersey 08544 USA

We show that classical many-particle systems interacting with certain soft pair interactions in two dimensions exhibit novel low-temperature behaviors. Ground states span from disordered to crystalline. At some densities, a large fraction of normal-mode frequencies vanish. Lattice ground-state configurations have more vanishing frequencies than disordered ground states at the same density and exhibit vanishing shear moduli. For the melting transition from a crystal, the thermal expansion coefficient is negative. These unusual results are attributed to the topography of the energy landscape.

关键词： Ground state

来源：评论

学校读者我要写书评

暂无评论

Dense packings of polyhedra: Platonic and Archimedean solids

引用

Physical Review E 2009年第4期80卷 041104-041104页

作者： S. Torquato Y. Jiao Department of Chemistry Princeton University Princeton New Jersey 08544 USA Princeton Center for Theoretical Science Princeton University Princeton New Jersey 08544 USA Princeton Institute for the Science and Technology of Materials Princeton University Princeton New Jersey 08544 USA Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA School of Natural Sciences Institute for Advanced Study Princeton New Jersey 08540 USA Department of Mechanical and Aerospace Engineering Princeton University Princeton New Jersey 08544 USA

Understanding the nature of dense particle packings is a subject of intense research in the physical, mathematical, and biological sciences. The preponderance of previous work has focused on spherical particles and very little is known about dense polyhedral packings. We formulate the problem of generating dense packings of nonoverlapping, nontiling polyhedra within an adaptive fundamental cell subject to periodic boundary conditions as an optimization problem, which we call the adaptive shrinking cell (ASC) scheme. This optimization problem is solved here (using a variety of multiparticle initial configurations) to find the dense packings of each of the Platonic solids in three-dimensional Euclidean space R3, except for the cube, which is the only Platonic solid that tiles space. We find the densest known packings of tetrahedra, icosahedra, dodecahedra, and octahedra with densities 0.823…, 0.836…, 0.904…, and 0.947…, respectively. It is noteworthy that the densest tetrahedral packing possesses no long-range order. Unlike the densest tetrahedral packing, which must not be a Bravais lattice packing, the densest packings of the other nontiling Platonic solids that we obtain are their previously known optimal (Bravais) lattice packings. We also derive a simple upper bound on the maximal density of packings of congruent nonspherical particles and apply it to Platonic solids, Archimedean solids, superballs, and ellipsoids. Provided that what we term the “asphericity” (ratio of the circumradius to inradius) is sufficiently small, the upper bounds are relatively tight and thus close to the corresponding densities of the optimal lattice packings of the centrally symmetric Platonic and Archimedean solids. Our simulation results, rigorous upper bounds, and other theoretical arguments lead us to the conjecture that the densest packings of Platonic and Archimedean solids with central symmetry are given by their corresponding densest lattice packings. This can be regarded to be

关键词： Optimization

来源：评论

学校读者我要写书评

暂无评论

Interactions leading to disordered ground states and unusual low-temperature behavior

引用

Physical Review E 2009年第3期80卷 031105-031105页

作者： Robert D. Batten Frank H. Stillinger Salvatore Torquato Department of Chemical Engineering Princeton University Princeton New Jersey 08544 USA Department of Chemistry Princeton University Princeton New Jersey 08544 USA Princeton Materials Institute Princeton University Princeton New Jersey 08544 USA Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA Princeton Center for Theoretical Science Princeton University Princeton New Jersey 08544 USA School of Natural Sciences Institute for Advanced Study Princeton New Jersey 08544 USA

We have shown that any pair potential function v(r) possessing a Fourier transform V(k) that is positive and has compact support at some finite wave number K yields classical disordered ground states for a broad density range [R. D. Batten, F. H. Stillinger, and S. Torquato, J. Appl. Phys. 104, 033504 (2008)]. By tuning a constraint parameter χ (defined in the text), the ground states can traverse varying degrees of local order from fully disordered to crystalline ground states. Here, we show that in two dimensions, the “k-space overlap potential,” where V(k) is proportional to the intersection area between two disks of diameter K whose centers are separated by k, yields anomalous low-temperature behavior, which we attribute to the topography of the underlying energy landscape. At T=0, for the range of densities considered, we show that there is continuous energy degeneracy among Bravais-lattice configurations. The shear elastic constant of ground-state Bravais-lattice configurations vanishes. In the harmonic regime, a significant fraction of the normal modes for both amorphous and Bravais-lattice ground states have vanishing frequencies, indicating the lack of an internal restoring force. Using molecular-dynamics simulations, we observe negative thermal-expansion behavior at low temperatures, where upon heating at constant pressure, the system goes through a density maximum. For all temperatures, isothermal compression reduces the local structure of the system unlike typical single-component systems.

关键词： Ground state

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：