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Multiple Magnetic Pole Reversals and Mössbauer Studies in Molecular-based Mixed Valency Ferrimagnet {[N(n-C4H9)4][MIIFeIII(C2O4)3]}n (M=Zn, Fe)

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Physics Procedia 2012年 25卷 375-381页

作者： Qing Lin Chenglong Lei Guodong Tang Qingmei Zhang Xinlong Dong Fupei Liang Ruijun Wang Siliang Zeng Yun He College of Physics and Technology Guangxi Normal University Guilin 541004 China Department of Information Technology Hainan Medical College Haikou 571101 China College of Chemistry and Chemical Engineering Guangxi Normal University Guilin 541004China Institute of Applied Physics and Computational Mathematics Beijing 100088 China

The Molecule magnets Materials {[N(n-C4H9)4][MIIFeIII(C2O4)3]}n (M=Zn Fe) were investigated by magnetic measurements and Mössbauer spectroscopy .In the complex {[N(n-C4H9)4][ZnII0.03FeII0.97 FeIII(C2O4)3]}n detailed investigation of the ferromagnetism behaviour, and a compensation temperature has found with the field being less than 1KOe. And the 57Fe Mössbauer measurements had been carried out in {[N(n-C4H9)4][FeIIFeIII(C2O4)3]}n to investigate the mixed valency character and antiferromagnetic coupling. Some ferrimagnets consisting of magnetic anisotropy ions and two or more types of antiferromagnetically ordered magnetic ions exhibit this behavior. As the temperature was lowered to 40 K, the FeIII doublet subspectrum almost completely turns into a sextet subspectrum. The hyperfine magnetic field increases as the temperature decreasing.

关键词： Molecule-based magnet Oxalate Mössbauer spectroscopy spin glass

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Magnetic Studies in Rare Earth-iron Oxalate-bridged Complexes MFe(C2O4)3·9H2O (M=Ce, Pr)

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Physics Procedia 2012年 25卷 369-374页

作者： Qing Lin Chenglong Lei Hui Zhang Xuehui Long Jianmei Xu Fupei Liang Ruijun Wang Siliang Zeng Yun He College of Physics and Technology Guangxi Normal University Guilin 541004 China Department of Information Technology Hainan Medical College Haikou 571101 China College of Chemistry and Chemical Engineering Guangxi Normal University Guilin 541004China Institute of Applied Physics and Computational Mathematics Beijing 100088 China

The rare earth-iron oxalate-bridged complexes CeFe(C2O4)3·9H2O and PrFe(C2O4)3·9H2O have been synthesized. In the sample CeFe(C2O4)3·9H2O, the magnetic susceptibilities of the compound can be fit to the Curie-Weiss law and Weiss paramagnetic Curie temperature of θ=-*** hyperfine field parameters show that the dependent of the hyperfine field and the spontaneous magnetization and that of the spontaneous magnetization and temperature in the latticed FeII and *** are a clear bifurcation phenomenon of the field-cooled (MFC) and Zero-field-cooled (MZFC) magnetization curves at the Néel temperature (4 K).In the sample PrFe(C2O4)3·9H2O,the Weiss paramagnetic Curie temperature θ=-2.7 K,There are a bifurcation of the ZFC and FC plots at the Néel temperature (6 K).The negative Weiss constant indicates an intramolecular antiferromagnetic coupling interaction between the adjacent Fe(II) and Fe(III) ions through the oxalate *** oxalate group has been shown to be an excellent bridging ligand in supporting the magnetic exchange interaction.

关键词： Oxalate rare earth materials susceptibility magnetic interaction

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Microstructural degeneracy associated with a two-point correlation function and its information content

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Physical Review E 2012年第5期85卷 051140-051140页

作者： C. J. Gommes Y. Jiao S. Torquato Department of Chemical Engineering University of Liège Liège 4000 Belgium Department of Chemistry Princeton University Princeton New Jersey 08544 USA Department of Physics 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 Princeton Institute for the Science and Technology of Materials Princeton University Princeton New Jersey 08544 USA

A two-point correlation function provides a crucial yet an incomplete characterization of a microstructure because distinctly different microstructures may have the same correlation function. In an earlier Letter [Gommes, Jiao, and Torquato, Phys. Rev. Lett. 108, 080601 (2012)], we addressed the microstructural degeneracy question: What is the number of microstructures compatible with a specified correlation function? We computed this degeneracy, i.e., configurational entropy, in the framework of reconstruction methods, which enabled us to map the problem to the determination of ground-state degeneracies. Here, we provide a more comprehensive presentation of the methodology and analyses, as well as additional results. Since the configuration space of a reconstruction problem is a hypercube on which a Hamming distance is defined, we can calculate analytically the energy profile of any reconstruction problem, corresponding to the average energy of all microstructures at a given Hamming distance from a ground state. The steepness of the energy profile is a measure of the roughness of the energy landscape associated with the reconstruction problem, which can be used as a proxy for the ground-state degeneracy. The relationship between this roughness metric and the ground-state degeneracy is calibrated using a Monte Carlo algorithm for determining the ground-state degeneracy of a variety of microstructures, including realizations of hard disks and Poisson point processes at various densities as well as those with known degeneracies (e.g., single disks of various sizes and a particular crystalline microstructure). We show that our results can be expressed in terms of the information content of the two-point correlation functions. From this perspective, the a priori condition for a reconstruction to be accurate is that the information content, expressed in bits, should be comparable to the number of pixels in the unknown microstructure. We provide a formula to calculate the

关键词： MICROSTRUCTURE CORRELATION (Statistics) INFORMATION theory ENTROPY (Information theory) GROUND state (Quantum mechanics) MONTE Carlo method POISSON processes

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Nonlinear Geometric Effects in Mechanical Bistable Morphing Structures

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Physical Review Letters 2012年第11期109卷 114302-114302页

作者： Zi Chen Qiaohang Guo Carmel Majidi Wenzhe Chen David J. Srolovitz Mikko P. Haataja Department of Mechanical and Aerospace Engineering Princeton University Princeton New Jersey 08544 USA Princeton Institute for the Science and Technology of Materials (PRISM) Princeton University Princeton New Jersey 08544 USA Department of Biomedical Engineering Washington University St. Louis Missouri 63130 USA College of Materials Science and Engineering Fuzhou University Fuzhou Fujian 350108 China Department of Mathematics and Physics Fujian University of Technology Fuzhou Fujian 350108 China Department of Mechanical Engineering Carnegie Mellon University Pittsburgh Pennsylvania 15213 USA Department of Materials Science and Engineering Fujian University of Technology Fuzhou Fujian 350108 China Institute for High Performance Computing 1 Fusionopolis Way Singapore 138632 Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA School of Mathematics Institute for Advanced Study Princeton New Jersey 08540 USA

Bistable structures associated with nonlinear deformation behavior, exemplified by the Venus flytrap and slap bracelet, can switch between different functional shapes upon actuation. Despite numerous efforts in modeling such large deformation behavior of shells, the roles of mechanical and nonlinear geometric effects on bistability remain elusive. We demonstrate, through both theoretical analysis and tabletop experiments, that two dimensionless parameters control bistability. Our work classifies the conditions for bistability, and extends the large deformation theory of plates and shells.

关键词： NONLINEAR theories DEFORMATIONS (Mechanics) PARAMETER estimation OPTICAL bistability STRUCTURAL shells PLATES (engineering) CRYSTAL structure

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A framework for relating neural activity to freely moving behavior

A framework for relating neural activity to freely moving be...

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Justin D. Foster Paul Nuyujukian Oren Freifeld Stephen I. Ryu Michael J. Black Krishna V. Shenoy Department of Electrical Engineering University of Stanford Stanford CA USA Bioengineering and Stanford Medical School University of Stanford Stanford CA USA Division of Applied Mathematics Brown University Providence RI USA Department of Neurosurgery Palo Alto Medical Foundation Palo Alto CA USA Department of Computer Science Brown University Providence RI USA Departments of Electrical Engineering Bioengineering and Neurobiology Neurosciences Program Neurosciences Program University of Stanford Stanford CA USA

Two research communities, motor systems neuroscience and motor prosthetics, examine the relationship between neural activity in the motor cortex and movement. The former community aims to understand how the brain controls and generates movement; the latter community focuses on how to decode neural activity as control signals for a prosthetic cursor or limb. Both have made progress toward understanding the relationship between neural activity in the motor cortex and behavior. However, these findings are tested using animal models in an environment that constrains behavior to simple, limited movements. These experiments show that, in constrained settings, simple reaching motions can be decoded from small populations of spiking neurons. It is unclear whether these findings hold for more complex, full-body behaviors in unconstrained settings. Here we present the results of freely-moving behavioral experiments from a monkey with simultaneous intracortical recording. We investigated neural firing rates while the monkey performed various tasks such as walking on a treadmill, reaching for food, and sitting idly. We show that even in such an unconstrained and varied context, neural firing rates are well tuned to behavior, supporting findings of basic neuroscience. Further, we demonstrate that the various behavioral tasks can be reliably classified with over 95% accuracy, illustrating the viability of decoding techniques despite significant variation and environmental distractions associated with unconstrained behavior. Such encouraging results hint at potential utility of the freely-moving experimental paradigm.

关键词： Legged locomotion Maximum likelihood decoding Kinematics Animals Educational institutions Cameras Neuroscience

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Erratum to: “Morphology based particle segregation by electrostatic charge” [J. Aerosol Sci. 39 (2008) 785–792]

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Journal of Aerosol Science 2013年 58卷 172-172页

作者： Rajan K. Chakrabarty Hans Moosmüller Mark A. Garro W. Patrick Arnott Jay G. Slowik Eben S. Cross Jeong-Ho Han Paul Davidovits Timothy B. Onasch Douglas R. Worsnop Chemical Physics Program University of Nevada Reno NV 89557 USA Desert Research Institute Nevada System of Higher Education Reno NV 89512 USA Division of Engineering and Applied Sciences Harvard University Cambridge MA 02138 USA Department of Physics University of Nevada Reno NV 89517 USA Department of Chemistry University of Toronto Ontario Canada M5S 3H6 Department of Chemistry Boston College Chestnut Hill MA 02467 USA Aerodyne Research Inc. Billerica MA 01821 USA

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Optimizing cooperative cognitive radio networks with opportunistic access

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Journal of Computer Networks and Communications 2012年

作者： Zafar, Ammar Alouini, Mohamed-Slim Chen, Yunfei Radaydeh, Redha M. Electrical Engineering Program KAUST Al Khawarizmi Applied Mathematics Building 1 Mail Box 2675 Makkah Province Thuwal 23955-6900 Saudi Arabia School of Engineering University of Warwick Coventry CV4 7AL United Kingdom Electrical Engineering Department KAUST Thuwal 23955-6900 Saudi Arabia Department of Electrical and Computer Engineering Texas AandM University Texas AandM Engineering Building Education City Doha Qatar

Optimal resource allocation for cooperative cognitive radio networks with opportunistic access to the licensed spectrum is studied. Resource allocation is based on minimizing the symbol error rate at the receiver. Both the cases of all-participate relaying and selective relaying are considered. The objective function is derived and the constraints are detailed for both scenarios. It is then shown that the objective functions and the constraints are nonlinear and nonconvex functions of the parameters of interest, that is, source and relay powers, symbol time, and sensing time. Therefore, it is difficult to obtain closed-form solutions for the optimal resource allocation. The optimization problem is then solved using numerical techniques. Numerical results show that the all-participate system provides better performance than its selection counterpart, at the cost of greater resources. © 2012 Ammar Zafar et al.

关键词： Resource allocation

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The Role of Gas-phase O2 in CO oxidation over CuO-Co3O4-CeO2 with High Catalytic Performance

The Role of Gas-phase O2 in CO oxidation over CuO-Co3O4-CeO2...

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第十六届全国催化学术会议

作者： Zhigang Liu Zili Wu Xihong Peng Sheng Dai School of Chemistry and Chemical Engineering Hunan UniversityChangsha 410082China Chemical Sciences DivisionOak Ridge National LaboratoryOak RidgeTennessee 37831United States Department of Applied Sciences and MathematicsArizona State UniversityMesaArizona 85212United States Chemical Sciences DivisionOak Ridge National LaboratoryOak RidgeTennessee 37831United States Department of Chemistry University of TennesseeKnoxvilleTennessee 37996-1600United States

CuO-Co3O4-CeO2 synthesized by co-precipitation was found to possess high catalytic performance at room temperature(56%of CO conversion at 25℃)or even lower reaction temperature(46%of CO conversion at 0 ℃).

关键词： CuO-Co3O4-CeO2 CO oxidation Mechanism

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Current-Induced Membrane Discharge

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Physical Review Letters 2012年第10期109卷 108301-108301页

作者： M. B. Andersen M. van Soestbergen A. Mani H. Bruus P. M. Biesheuvel M. Z. Bazant Department of Micro- and Nanotechnology Technical University of Denmark DTU Nanotech Building 345 East DK-2800 Kongens Lyngby Denmark Wetsus Centre of Excellence for Sustainable Water Technology Agora 1 8934 CJ Leeuwarden The Netherlands Department of Applied Physics Eindhoven University of Technology Den Dolech 2 5612 AZ Eindhoven The Netherlands Department of Mechanical Engineering Stanford University Stanford California 94305 USA Department of Environmental Technology Wageningen University Bornse Weilanden 9 6708 WG Wageningen The Netherlands Departments of Chemical Engineering and Mathematics Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA

Possible mechanisms for overlimiting current (OLC) through aqueous ion-exchange membranes (exceeding diffusion limitation) have been debated for half a century. Flows consistent with electro-osmotic instability have recently been observed in microfluidic experiments, but the existing theory neglects chemical effects and remains to be quantitatively tested. Here, we show that charge regulation and water self-ionization can lead to OLC by “current-induced membrane discharge” (CIMD), even in the absence of fluid flow, in ion-exchange membranes much thicker than the local Debye screening length. Salt depletion leads to a large electric field resulting in a local pH shift within the membrane with the effect that the membrane discharges and loses its ion selectivity. Since salt co-ions, H+ ions, and OH− ions contribute to OLC, CIMD interferes with electrodialysis (salt counterion removal) but could be exploited for current-assisted ion exchange and pH control. CIMD also suppresses the extended space charge that leads to electro-osmotic instability, so it should be reconsidered in both models and experiments on OLC.

关键词： ION-permeable membranes SALT ELECTRO-osmosis MICROFLUIDICS HYDROGEN-ion concentration ELECTRIC discharges ELECTRIC fields

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Fe-substitution Effects on the Cu-spin Correlation in La 2-x Sr x Cu 1-y Fe y O 4 Studied by Muon Spin Relaxation

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Physics Procedia 2012年 30卷 275-278页

作者： K. Suzuki T. Adachi Y. Tanabe H. Sato Risdiana Y. Ishii T. Suzuki I. Watanabe Y. Koike Department of Applied Physics Graduate School of Engineering Tohoku University 6-6-05 Aoba Aramaki Aoba-ku Sendai 980-8579 Japan Advanced Meson Science Laboratory Nishina Center for Accelerator-Based Science The Institute of Physical and Chemical Research (RIKEN) 2-1 Hirosawa Wako 351-0198 Japan Department of Physics Faculty of Mathematics and Natural Sciences Padjadjaran University Jl. Raya Bandung-Sumedang Km. 21 Jatinangor 45363 Indonesia

We have investigated the low-frequency Cu-spin dynamics of partially Fe-substituted La 2−x SrxCu 1−y FeyO4 with x = 0.06 – 0.235 and y = 0.01 from zero-field muon-spin-relaxation measurements. We find that the magnetic transition temperature, T mid N , is enhanced through the 1% Fe substitution in a wide range of hole concentration per Cu, N p, where superconductivity appears in La 2−x Sr x CuO 4 . The T mid N exhibits a local maximum at p ∼ 0.115 and exists even in the overdoped regime of p > 0.15. To the surprise, T mid N in the overdoped regime of 0.15 < p ≤ 0.225 is larger than in the underdoped regime of 0.05 ≤ p ≤ 0.09. These results suggest that the substitution of Fe as a magnetic impurity is effective for the stabilization of the so-called stripe order in high- T c cuprates in the underdoped regime and that the nature of the magnetic order induced through the Fe substitution in the overdoped regime might be different from that in the underdoped regime.

关键词： Fe-substitution effect La 2−x Sr x Cu 1−y Fe y O 4 muon spin relaxation

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