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Implicit Purification for Temperature-Dependent Density Matrices

Anders M. N. Niklasson2003-11-20arXiv

An implicit purification scheme is proposed for calculation of the temperature-dependent, grand canonical single-particle density matrix, given as a Fermi operator expansion in terms of the Hamiltonian. The computational complexity is shown to scale with the logarithm of the polynomial order of the expansion, or equiv…

Materials Science

Suppression of the Magnetic Phase Transition in Manganites Close to the Metal-Insulator Crossover

F. Rivadulla、J. Rivas、J. B. Goodenough2003-11-20arXiv

We report the suppression of the magnetic phase transition in La1-xCaxMnO3 close to the localized-to-itinerant electronic transition, i.e. at x = 0.2 and x = 0.5. A new crossover temperature Tf can be defined for these compositions instead of TC. Unlike in common continuous magnetic phase transition the susceptibility…

Strongly Correlated ElectronsMaterials Science

Andrade, Omori and Time-to-failure Laws from Thermal Noise in Material Rupture

A. Saichev、D. Sornette2003-11-20arXiv

Using the simplest possible ingredients of a rupture model with thermal fluctuations, we provide an analytical theory of three ubiquitous empirical observations obtained in creep (constant applied stress) experiments: the initial Andrade-like and Omori-like $1/t$ decay of the rate of deformation and of fiber ruptures…

Materials Science

Current-induced transverse spin wave instability in a thin nanomagnet

M. L. Polianski、P. W. Brouwer2003-11-20arXiv

We show that an unpolarized electric current incident perpendicular to the plane of a thin ferromagnet can excite a spin-wave instability transverse to the current direction if source and drain contacts are not symmetric. The instability, which is driven by the current-induced ``spin-transfer torque'', exists for one…

Materials ScienceMesoscale and Nanoscale Physics

Magnetization of ultrathin (Ga,Mn)As layers

R. Mathieu、B. S. Sørensen、J. Sadowski 等 9 位作者2003-11-20Physical review. B, Condensed matter

Kerr rotation and superconducting quantum interference device magnetometry measurements were performed on ultrathin $({\mathrm{Ga}}_{0.95}{\mathrm{Mn}}_{0.05})\mathrm{As}$ layers. The thinner layers (below 250 \AA{}) exhibit magnetic properties different than those of thicker ones, associated with different microstruc…

Physics of Superconductivity and MagnetismMagnetic and transport properties of perovskites and related materialsZnO doping and properties

A Paramagnetic CEST Agent for Imaging Glucose by MRI

Shanrong Zhang、R. Trokowski、A. Dean Sherry2003-11-20Journal of the American Chemical Society

The europium(III) complex of a DOTA-tetraamide ligand (DOTA = 1,4,7,10-tetraazacyclododecane-N,N',N' ',N' ''-tetraacetic acids) containing two phenyl boronate pendent arms binds glucose reversibly with an association constant of 383 M-1 at pH 7. Glucose binding results in slowing of water exchange between a single Eu(…

Lanthanide and Transition Metal ComplexesElectron Spin Resonance StudiesAdvanced MRI Techniques and Applications

Mechanistic Modeling of Polymer Pyrolysis: Polypropylene

Todd M. Kruse、Hsi‐Wu Wong、Linda J. Broadbelt2003-11-20Macromolecules

The pyrolysis of polypropylene was modeled at the mechanistic level to predict the formation of low molecular weight products. Differential equations were developed that describe the evolution of the moments of structurally distinct polymer species. Unique polymer groups were devised that allowed the necessary polymer…

Thermal and Kinetic AnalysisFree Radicals and AntioxidantsPolymer crystallization and properties

Chaos-induced breaking of the Franck-Condon approximation

Hisatsugu Yamasaki、Yuhei Natsume、Akira Terai 等 4 位作者2003-11-20arXiv

We investigate the vibrational structure of electronic spectra for the transition from the non-degenerate $A$ state to $E$ states in $E_g\otimes e_g$ Jahn-Teller systems with the trigonal field included. In connection with the underlying chaotic behavior for vibronic energy levels in this model reported by the present…

nlin.CDMaterials Science

Trapped field and related properties in a superconducting disk magnetized by pulse field

C Y He、Y Hou、L Liu 等 4 位作者2003-11-20arXiv

The distributions of the magnetic field and temperature in a superconducting-disk magnetized by pulse field, and the levitation force between this disk and a permanent magnet are calculated from first principles. The calculation is based upon the current motion and the heat diffusion equations in the disk. The critica…

SuperconductivityMaterials Science

Synthesis of High-Quality Metal Sulfide Nanoparticles from Alkyl Xanthate Single Precursors in Alkylamine Solvents

Narayan Pradhan、Beni Katz、Shlomo Efrima2003-11-20The Journal of Physical Chemistry B

A synthesis of various metal sulfide nanoparticles at relatively low temperature with use of a single precursor under ambient conditions is described. Metal alkyl xanthates (as well as thiocarbamates and thiocarbonates) are used as the precursor. Lewis base alkylamine solvents promote the reaction at low temperatures…

Chalcogenide Semiconductor Thin FilmsQuantum Dots Synthesis And PropertiesCopper-based nanomaterials and applications

Picosecond Energy Transfer in Quantum Dot Langmuir−Blodgett Nanoassemblies

Marc Achermann、Melissa A. Petruska、S. A. Crooker 等 4 位作者2003-11-20The Journal of Physical Chemistry B

We study spectrally resolved dynamics of Förster energy transfer in single monolayers and bilayers of semiconductor nanocrystal quantum dots assembled using Langmuir−Blodgett (LB) techniques. For a single monolayer, we observe a distribution of transfer times from ∼50 ps to ∼10 ns, which can be quantitatively modeled…

Semiconductor Quantum Structures and DevicesChalcogenide Semiconductor Thin FilmsQuantum Dots Synthesis And Properties

n‐Butyl acrylate based latex interpenetrating polymer networks used as processing modifiers and impact modifiers of poly(vinyl chloride)

Liucheng Zhang、Mingwang Pan、Jian Zhang2003-11-19Journal of Applied Polymer Science

Abstract A latex interpenetrating polymer network (LIPN), consisting of poly( n ‐butyl acrylate), poly( n ‐butyl acrylate‐ co ‐ethylhexyl acrylate), and poly(methyl methacrylate‐ co ‐ethyl acrylate) and labeled PBEM, with 1,4‐butanediol diacrylate as a crosslinking agent was synthesized by three‐stage emulsion polymer…

Polymer Science and PVCbiodegradable polymer synthesis and propertiesAdvanced Polymer Synthesis and Characterization

Chitosan hollow fiber membranes

Zofia Modrzejewska、Wojciech Eckstein2003-11-19Biopolymers

Chitosan hollow fibers were produced by wet spinning, taking advantage of the unique rheological properties of highly viscous chitosan solutions in acetic acid. The mechanical and separation properties of hollow fibers were tested. The mechanical properties were determined by measuring tensile force, tensile stress, e…

Advanced Cellulose Research StudiesPolymer Surface Interaction StudiesElectrospun Nanofibers in Biomedical Applications

Crystal structure of a DNA binding protein from the hyperthermophilic euryarchaeon Methanococcus jannaschii

Ganggang Wang、Rong Guo、Mark Bartlam 等 8 位作者2003-11-19Protein Science

The Sac10b family consists of a group of highly conserved DNA binding proteins from both the euryarchaeotal and the crenarchaeotal branches of Archaea. The proteins have been suggested to play an architectural role in the chromosomal organization in these organisms. Previous studies have mainly focused on the Sac10b p…

Enzyme Structure and FunctionRNA and protein synthesis mechanismsGenomics and Phylogenetic Studies

Magnetic Resonance Studies of Hierarchically Ordered Replicas of Wood Cellular Structures Prepared by Surfactant-Mediated Mineralization

Li‐Qiong Wang、Yongsoon Shin、William D. Samuels 等 7 位作者2003-11-19The Journal of Physical Chemistry B

Hierarchically ordered positive and negative replicas of wood cellular structures prepared using surfactant templating methods under acidic and basic conditions have been studied by means of continuous flow hyperpolarized 129 Xe NMR, solid-state MAS 13 C, 29 Si, and 2D WISE NMR spectroscopic techniques. 129 Xe NMR dat…

Aerogels and thermal insulationAdvanced Cellulose Research StudiesMesoporous Materials and Catalysis

Evolution of Enzymatic Activity in the Enolase Superfamily: Structural and Mutagenic Studies of the Mechanism of the Reaction Catalyzed by o- Succinylbenzoate Synthase from Escherichia coli ,

Vadim A. Klenchin、Erika A. Taylor、J.A. Gerlt 等 4 位作者2003-11-19Biochemistry

o-Succinylbenzoate synthase (OSBS) from Escherichia coli, a member of the enolase superfamily, catalyzes an exergonic dehydration reaction in the menaquinone biosynthetic pathway in which 2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate (SHCHC) is converted to 4-(2'-carboxyphenyl)-4-oxobutyrate (o-succinylbenzoat…

Enzyme Structure and FunctionCancer, Hypoxia, and MetabolismMicrobial Metabolic Engineering and Bioproduction

Preparation and structural characterization of ferromagneticMn5Si3Cxfilms

C. Sürgers、M. Gajdzik、G. Fischer 等 6 位作者2003-11-19Physical review. B, Condensed matter

Carbon-doped Mn-Si films prepared by magnetron sputtering at elevated substrate temperatures exhibit ferromagnetic order for compositions around ${\mathrm{Mn}}_{5}{\mathrm{Si}}_{3}{\mathrm{C}}_{x}$ $(x>0)$ in contrast to the antiferromagnetic ${\mathrm{Mn}}_{5}{\mathrm{Si}}_{3}$ compound. In these sputtered samples…

Magnetic Properties of AlloysZnO doping and propertiesRare-earth and actinide compounds

Deflection control of a flexible beam using shape memory alloy actuators

Mehrdad Moallem2003-11-19Smart Materials and Structures

This paper presents a nonlinear control scheme for deflection control of a flexible beam system using shape memory alloy (SMA) smart actuators. Due to their interesting properties such as force generation capacity, possibility of miniaturization, and power consumption, these devices have been gaining increased popular…

Aeroelasticity and Vibration ControlStructural Engineering and Vibration AnalysisShape Memory Alloy Transformations

Fabrication and Characterization of Carbon Nanofiber-Based Vertically Integrated Schottky Barrier Junction Diodes

Xiaojing Yang、Michael Guillorn、Derek Austin 等 10 位作者2003-11-19Nano Letters

We report on the fabrication and electrical characterization of active nanoscale electronic devices using single vertically aligned carbon nanofibers (VACNFs). A rectifying behavior consistent with a 0.3 eV Schottky barrier was found. Experimental results indicate that a region of semiconducting SiC is formed directly…

Carbon Nanotubes in CompositesNanowire Synthesis and ApplicationsGraphene research and applications

Langmuir−Blodgett Films of Charge-Transfer Complexes between an Amphiphilic Monopyrrolo-TTF and TCNQ Derivatives

Tomoyuki Akutagawa、Masanori Uchigata、Tatsuo Hasegawa 等 8 位作者2003-11-19The Journal of Physical Chemistry B

Electrically active Langmuir−Blodgett (LB) films based on charge-transfer (CT) complexes between an amphiphilic monopyrrolo-tetrathiafulvalene (MP-TTF) electron donor and different derivatives of the electron acceptor 7,7,8,8-tetracyano- p -quinodimethane (TCNQ), namely, 2,5-difluoro-TCNQ, fluoro-TCNQ, TCNQ, decyl-TCN…

Organic and Molecular Conductors ResearchForce Microscopy Techniques and ApplicationsMagnetism in coordination complexes