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Preparation and Properties of Nanoporous Triblock Copolymer Membranes

Guojun Liu、Jianfu Ding、Sean Stewart1999-03-08Angewandte Chemie International Edition

"Unplug those pores!" could be a slogan common to cosmetologists and polymer chemists. Membranes with nanochannels can be obtained by first forming a film by casting a solution of a triblock and homopolymer mixture, then selectively cross-linking domains in the film by photolysis, and finally forming nanochannels thro…

Membrane Separation and Gas TransportBlock Copolymer Self-AssemblyNanopore and Nanochannel Transport Studies

On the high-temperature phase transitions of CsH2PO4: A polymorphic transition? A transition to a superprotonic conducting phase?

E. Ortiz、R.A. Vargas、B.‐E. Mellander1999-03-08The Journal of Chemical Physics

X-ray diffraction, thermogravimetric (TGA), differential scanning calorimetric (DSC), and impedance analysis were used to study the reported high-temperature phase transitions at 107, 149, 230, and 256 °C in crystals of cesium dihydrogen phosphate, CsH2PO4 (CDP). Our results show strong evidence that at all these temp…

Crystal Structures and PropertiesNonlinear Optical Materials ResearchSolid-state spectroscopy and crystallography

Structural Instability of the Charge Ordered Compound Nd 0.5 Sr 0.5 MnO 3 under a Magnetic Field

R. Mahendiran、M. R. Ibarra、A. Maignan 等 8 位作者1999-03-08Physical Review Letters

We report an anomalous magnetostriction behavior of the charge ordered compound ${\mathrm{Nd}}_{0.5}{\mathrm{Sr}}_{0.5}{\mathrm{MnO}}_{3}$. We have found that the applied magnetic field not only gives rise to a large negative magnetoresistance but also produces a huge positive magnetovolume effect. This unusual effect…

Magnetic and transport properties of perovskites and related materialsShape Memory Alloy TransformationsMultiferroics and related materials

Inclusive Electron-Nucleus Scattering at Large Momentum Transfer

J. Arrington、Christopher Armstrong、T. Averett 等 43 位作者1999-03-08Physical Review Letters

Inclusive electron scattering is measured with 4.045 GeV incident beam energy from C, Fe, and Au targets. The measured energy transfers and angles correspond to a kinematic range for Bjorken $x>1$ and momentum transfers from ${Q}^{2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1--7(\mathrm{GeV}/c{)}^{2}$. Whe…

X-ray Spectroscopy and Fluorescence AnalysisNuclear Physics and ApplicationsElectron and X-Ray Spectroscopy Techniques

Antimonides with the half-Heusler structure: New thermoelectric materials

K. Mastronardi、David P. Young、C.-C. Wang 等 6 位作者1999-03-08Applied Physics Letters

The thermoelectric properties near ambient temperature of half-Heusler alloys based on LnPdSb, where Ln=Ho, Er, and Dy are reported. The Seebeck coefficients are large, between 60 and 250 μV/K, and the materials are p type. The resistivities are between 0.6 and 20 mΩ cm. Thermal conductivities are between approximatel…

Advanced Thermoelectric Materials and DevicesTopological Materials and PhenomenaHeusler alloys: electronic and magnetic properties

Anomalous Anisotropic Light Scattering in Ge-Doped Silica Glass

Peter G. Kazansky、Hiroyuki Inouye、Tsuneo Mitsuyu 等 7 位作者1999-03-08Physical Review Letters

Light scattering which peaks in the plane of light polarization is observed in glass pumped by intense laser radiation. The phenomenon is interpreted in terms of the angular distribution of photoelectrons in isotropic solid state materials.

Glass properties and applicationsLaser Material Processing TechniquesPhotorefractive and Nonlinear Optics

Cuprate core level line shapes for different Cu-O networks

K. Karlsson、O. Gunnarsson、O. Jepsen1999-03-08arXiv

We have studied the Cu core level photoemission spectra in the Anderson impurity model for cuprates with different Cu-O networks, dimensionalities (zero, one, two and three) and Cu valencies (two and three). We focus on the shape of the leading peak and obtain very good agreement with the experimental data. We show ho…

Materials ScienceStrongly Correlated Electrons

Phonon line shape in disordered A3C60 (A= K, Rb)

J. E. Han、O. Gunnarsson、V. Eyert1999-03-08arXiv

We present a calculation of the Hg phonon self-energy for a model of A3C60 (A= K, Rb). The orientational disorder of the C60 molecules is included, and the lowest order self-energy diagram is considered. The calculations illustrate that due to the violation of momentum conservation by the orientational disorder, Raman…

Materials Science

Successful Test of a Seamless van der Waals Density Functional

John F. Dobson、Jun Wang1999-03-08Physical Review Letters

We report the first microscopic (RPA) calculation of the van der Waals interaction between two self-consistent jellium metal slabs---from asymptotic separations down to full contact. We also present the first test of a recently proposed seamless van der Waals density functional, which reproduces the RPA results satisf…

Advanced Chemical Physics StudiesGraphene research and applicationsMolecular Junctions and Nanostructures

Berry-phase theory of proper piezoelectric response

David Vanderbilt1999-03-08arXiv

Recent theoretical advances have established that the electric polarization in an insulating crystal can be viewed as a multivalued quantity that is determined by certain Berry phases associated with the occupied Bloch bands. The application of this approach to the computation of piezoelectric coefficients is not enti…

Materials Science

Non-degenerate Two Photon Absorption Spectra of Si Nanocrystallites

Toshiaki Iitaka、Toshikazu Ebisuzaki1999-03-08arXiv

We propose an efficient linear-scaling time-dependent method for calculating nonlinear response function, and study the size effects in non-degenerate two photon absorption spectra of Si nanocrystallites by using semi-empirical pseudopotentials.

Mesoscale and Nanoscale PhysicsMaterials Sciencephysics.comp-ph

Efficient Catalysis of Polysiloxane Synthesis by Silicatein α Requires Specific Hydroxy and Imidazole Functionalities

Yan Zhou、Katsuhiko Shimizu、Jennifer N. Cha 等 5 位作者1999-03-08Angewandte Chemie International Edition

A protein isolated from a biosilica (shown schematically) catalyzes alkoxysilane polycondensation at neutral pH values and low temperatures. Replacement of either of two specific side chain functionalities (Ser-26 and His-165) significantly diminishes catalysis, supporting a reaction mechanism analogous to that of a w…

Enzyme Catalysis and Immobilizationbiodegradable polymer synthesis and propertiesEnzyme Production and Characterization

Freezing and melting of water in a single cylindrical pore: The pore-size dependence of freezing and melting behavior

Kunimitsu Morishige、Keiji Kawano1999-03-08OpenAlex

In order to clarify the origin of the hysteresis between freezing and melting of pore water, we performed x-ray diffraction measurements of water confined inside the cylindrical pores of seven kinds of siliceous MCM-41 (a member of ordered mesoporous materials denoted by Mobil Oil researchers) with different pore radi…

Phase Equilibria and ThermodynamicsMesoporous Materials and CatalysisAerogels and thermal insulation

Toughness of SMI-modified ABS alloys and the associated deformation behavior

P.‐Y. Ben Jar、Ru Yu Wu、Takashi Kuboki 等 5 位作者1999-03-07Journal of Applied Polymer Science

The mechanical toughness of modified ABS (acrylonitrile–butadiene–styrene) alloys was evaluated using Izod impact, tensile, and compact tension tests. The modified ABS alloys contain 20 wt % of styrene–N-phenylmaleimide (SMI) that is added to enhance the thermal resistance of the ABS. In this study, the effects of mat…

Mechanical Behavior of CompositesPolymer crystallization and propertiesNatural Fiber Reinforced Composites

Influence of styrene content on the hydrogenation of styrene-butadiene copolymer

Mousumi De Sarkar、Prajna P. De、Anil K. Bhowmick1999-03-07Journal of Applied Polymer Science

A hydrogenated styrene–butadiene copolymer (HSBR) was prepared by a diimide reduction of SBR in the latex stage. The influence of the styrene content on various reaction parameters, namely, time, temperature, and concentration of the reactants and the catalyst was studied. A comparatively lower temperature, longer tim…

Polymer crystallization and propertiesPolymer Nanocomposites and PropertiesAdvanced Physical and Chemical Molecular Interactions

Structure and physical properties of silk fibroin/polyacrylamide blend films

Giuliano Freddi、Masuhiro Tsukada、Silvia Beretta1999-03-07Journal of Applied Polymer Science

This article deals with the characterization of blend films obtained by mixing silk fibroin (SF) and polyacrylamide (PAAm). The DSC curves of SF/PAAm blend films showed overlapping of the main thermal transitions characteristic of the individual polymers. The exothermic peak at 218°C, assigned to the β-sheet crystalli…

Surface Modification and SuperhydrophobicityPolymer Surface Interaction StudiesSilk-based biomaterials and applications

Liquid crystals and flow elongation in a spider's silk production line

D.P. Knight、Fritz Vollrath1999-03-07Proceedings of the Royal Society B Biological Sciences

Our observations on whole mounted major ampullate silk glands suggested that the thread is drawn from a hyperbolic die using a pre–orientated lyotropic liquid crystalline feedstock. Polarizing microscopy of the gland's duct revealed two liquid crystalline optical textures: a curved pattern in the feedstock within the…

Plant Molecular Biology ResearchPlant Reproductive BiologySilk-based biomaterials and applications

Palladium Porphyrin Containing Zirconium Phosphonate Langmuir−Blodgett Films

Christine M. Nixon、Karine Le Claire、Fabrice Odobel 等 5 位作者1999-03-06Chemistry of Materials

The substituted tetraphenylporphyrins palladium 5,10,15,20-tetrakis(2‘,3‘,5‘,6‘-tetrafluorophenyl-4‘-octadecyloxyphosphonic acid)porphyrin ( 16 ) and palladium 5,10,15-tris(2‘,6‘-dichlorophenyl)-20-(2‘,3‘,5‘,6‘-tetrafluorophenyl-4‘-octadecyloxyphosphonic acid)porphyrin ( 17 ) have been studied as Langmuir monolayers a…

Molecular Sensors and Ion DetectionSupramolecular Chemistry and ComplexesPorphyrin and Phthalocyanine Chemistry

Frequency-Dependent Molecular Polarizability and Refractive Index: Are Substituent Contributions Additive?

Kristian O. Sylvester‐Hvid、Per‐Olof Åstrand、Mark A. Ratner 等 4 位作者1999-03-06The Journal of Physical Chemistry A

The frequency-dependent polarizabilities of a number of halogen-substituted benzene species are computed using ab-initio methods. The polarizability tensors are analyzed for possible additive properties. Simple group or atom additivity trivially fails (the overall polarizability is not a sum of isotropic atom or group…

Advanced Chemical Physics StudiesNonlinear Optical Materials ResearchSolid-state spectroscopy and crystallography

Determination of Low-Z Elements in Individual Environmental Particles Using Windowless EPMA

Chul‐Un Ro、János Osán、René Van Grieken1999-03-06Analytical Chemistry

The determination of low-Z elements such as carbon, nitrogen, and oxygen in atmospheric aerosol particles is of interest in studying environmental pollution. Conventional electron probe microanalysis technique has a limitation for the determination of the low-Z elements, mainly because the Be window in an energy-dispe…

X-ray Spectroscopy and Fluorescence AnalysisLaser-induced spectroscopy and plasmaElectron and X-Ray Spectroscopy Techniques