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X-ray Diffraction and 119Sn Mössbauer Spectroscopy Study of a New Phase in the Bi2Se3−SnSe System: SnBi4Se7

C. Vicente、José L. Tirado、Kopoin Adouby 等 6 位作者1999-04-09Inorganic Chemistry

First studies of the ternary system SnSe-Bi(2)Se(3) developed in 1960s and 1970s have revealed the existence of a nonstoichiometric trigonal phase with a wide range of compositions. In this study, an almost stoichiometric phase, corresponding to the composition SnBi(4)Se(7), has been identified and isolated. The struc…

Advanced Thermoelectric Materials and DevicesChalcogenide Semiconductor Thin FilmsPhase-change materials and chalcogenides

Hydrogen-Bond Interactions between Urethane−Urethane and Urethane−Ester Linkages in a Liquid Crystalline Poly(ester−urethane)

Fu-Sen Yen、Lieh‐Li Lin、Jin‐Long Hong1999-04-09Macromolecules

Five model compounds (U u, U s, DPT, DMT, and MB) and two liquid crystalline poly(ester−urethane)s with inherent urethane and internal and external ester groups were prepared to monitor the hydrogen-bond (H-bond) interactions of urethane−urethane and urethane−ester (including internal and external esters). The model c…

Liquid Crystal Research AdvancementsNeurobiology and Insect Physiology ResearchPolymer composites and self-healing

Electrodeposited Ceramic Single Crystals

Jay A. Switzer、Mark G. Shumsky、Eric W. Bohannan1999-04-09Science

Single-crystal films are essential for devices because the intrinsic properties of the material, rather than its grain boundaries, can be exploited. Cubic bismuth oxide has the highest known oxide ion mobility, which makes it useful for fuel cells and sensors, but it is normally only stable from 729 degrees to 825 deg…

Advancements in Solid Oxide Fuel CellsGas Sensing Nanomaterials and SensorsElectronic and Structural Properties of Oxides

Dissociation of N2, NO, and CO on Transition Metal Surfaces

Manos Mavrikakis、L. B. Hansen、J. J. Mortensen 等 5 位作者1999-04-08ACS symposium series

Using density functional theory we study the dissociation of N 2, NO, and CO on transition metal surfaces. We discuss an efficient method to locate the minimum energy path and the transition state, and review recent calculations using this method to determine the transition state for dissociation of N 2 on Ru(0001) an…

Catalytic Processes in Materials ScienceGas Sensing Nanomaterials and SensorsAmmonia Synthesis and Nitrogen Reduction

Cagelike Clusters as Models for the Isolated Hydroxyls of Silica: Ab Initio B3-LYP Calculations of the Interaction with Ammonia

Bartolomeo Civalleri、E. Garrone、Piero Ugliengo1999-04-08Langmuir

Structural, energetical, and vibrational features of cagelike clusters mimicking the isolated hydroxyl group at the surface of siliceous materials, both free and interacting with an ammonia molecule, are studied ab initio at the B3-LYP/DZP level of calculations. Two minimal model clusters, H 3 SiOH and F 3 SiOH, and f…

Zeolite Catalysis and SynthesisGlass properties and applicationsMesoporous Materials and Catalysis

Langmuir monolayers of C17, C19, and C21 fatty acids: Textures, phase transitions, and localized oscillations

Salvador Ramos、Rolando Castillo1999-04-08The Journal of Chemical Physics

The phase diagrams of Langmuir monolayers of heptadecanoic (C17), nonadecanoic (C19), and heneicosanoic (C21) acids have been determined from pressure-area isotherms, and from direct observations of the monolayers using Brewster angle microscopy. In this paper, we describe the observed domains, textures and phase boun…

Liquid Crystal Research AdvancementsSurfactants and Colloidal SystemsSpectroscopy and Quantum Chemical Studies

On the strength of shocked glasses

N. K. Bourne、J. C. F. Millett、J. E. Field1999-04-08Proceedings of the Royal Society A Mathematical Physical and Engineering Sciences

Shocked glasses suffer a particular failure mode in which they lose strength behind a propagating front that is known as a failure wave. The glass shows high strength, which reduces after some time to a lower value as the failure front passes. Such behaviour is investigated using plate–impact loading experiments over…

High-pressure geophysics and materialsGlass properties and applicationsBuilding materials and conservation

Glassy dynamics in DNA: Ruled by water of hydration?

Alexei P. Sokolov、H. Grimm、Richard Kahn1999-04-08The Journal of Chemical Physics

Inelastic neutron scattering spectra of DNA-fibers are analyzed using ideas formulated recently in the field of the glass transition. The analysis reveals two temperatures, namely, T∼180–200 K and T∼230 K, at which the dynamics of DNA exhibits qualitative changes. The former is similar to the glass transition temperat…

Protein Structure and DynamicsPolymer crystallization and propertiesMaterial Dynamics and Properties

Cooperative diffusion in colloidal mixtures

Gerhard Nägele、Johan Bergenholtz、Jan K. G. Dhont1999-04-08The Journal of Chemical Physics

In this work we develop a general method to examine cooperative diffusion, i.e., the partial dynamic structure factors, in multicomponent colloidal mixtures of spherical particles. Using a multivariable projection operator formalism based on the many-body Smoluchowski diffusion equation, we derive an exact microscopic…

Material Dynamics and PropertiesSurfactants and Colloidal SystemsNMR spectroscopy and applications

Self-Assembled Porphyrin−C60 and Porphycene−C60 Complexes via Metal Axial Coordination

Francis D’Souza、Gollapalli R. Deviprasad、Muhammad S. Rahman 等 4 位作者1999-04-08Inorganic Chemistry

Noncovalently linked electron donor-acceptor complexes consisting of either zinc tetraphenylporphyrin, (TPP)Zn, or zinc octaethylporphycene, (OEPc)Zn, as donor and pyridine appended C(60), py approximately C(60), as acceptor, via axial coordination of zinc, are reported. The UV-visible and (1)H NMR spectral studies re…

Carbon Nanotubes in CompositesPorphyrin and Phthalocyanine ChemistryFullerene Chemistry and Applications

Computer simulation studies of anisotropic systems. XXX. The phase behavior and structure of a Gay–Berne mesogen

Martin A. Bates、G. R. Luckhurst1999-04-08The Journal of Chemical Physics

The Gay–Berne potential is proving to be a valuable model with which to investigate the behavior of liquid crystals using computer simulation techniques. The potential contains four independent parameters which control the anisotropy in the attractive and repulsive interactions. The choice of these parameters is not s…

Liquid Crystal Research AdvancementsMaterial Dynamics and PropertiesSurfactants and Colloidal Systems

Molecular dynamic simulation of directional crystal growth

B. V. Costa、P. Z. Coura、O. N. Mesquita1999-04-08arXiv

We use molecular dynamic to simulate the directional growth of binary mixtures. our results compare very well with analitical and experimental results. This opens up the possibility to probe growth situations which are difficult to reach experimentally, being an important tool for further experimental and theoretical…

Materials Sciencecond-mat.stat-mech

A Model for the Optical Absorption in Porous Silicon Quantum Wires

Shouvik Datta、K. L. Narasimhan1999-04-08arXiv

In this paper, we analyse the optical absorption in porous silicon . This is the first attempt to explicitly demonstrate that it is not possible to extract the band gap of such low dimensional nanostructures like porous silicon from a Tauc plot of Square Root(alpha h nu) vs (h nu) . These objections are also valid for…

Mesoscale and Nanoscale PhysicsMaterials ScienceSoft Condensed Matter

Mono(di)nuclear Europium(III) Complexes of Macrobi(tri)cyclic Cryptands Derived from Diazatetralactams as Luminophores in Aqueous Solution

Chantal Galaup、Claude Picard、Bernard Cathala 等 7 位作者1999-04-07Helvetica Chimica Acta

To increase the excellent light-emitting properties of the Eu3+ ion, macrobicyclic and macrotricyclic ligands 7 – 10, incorporating a 18-membered tetralactam ring (acting as a lanthanide binding site) and a sensitizer group (2,2′-bipyridine or 2,2′-bipyridine 1,1′-dioxide moiety), were synthesized. The mononuclear and…

Magnetism in coordination complexesRadioactive element chemistry and processingLanthanide and Transition Metal Complexes

Characterization of Immobilized Poly-l-aspartate as a Metal Chelator

Elizabeth Gutiérrez、Thomasin C. Miller、Jose R. Gonzalez-Redondo 等 4 位作者1999-04-07Environmental Science & Technology

Poly- l -aspartic acid (PLAsp), which consists of ca. 50 Asp residues in a linear polypeptide, has been immobilized on controlled pore glass (CPG) and evaluated for its selectivity and binding strength in the complexation of metal ions from aqueous solutions. The carboxylate side chain of Asp (p K a = 5.4 ± 0.2) is th…

biodegradable polymer synthesis and propertiesMicroplastics and Plastic PollutionBiopolymer Synthesis and Applications

Two-dimensional photonic crystal polarizer

Chun Zhang、Jun Wan、Feng Qiao 等 4 位作者1999-04-07arXiv

A novel polarizer made from two-dimensional photonic bandgap materials was demonstrated theoretically. This polarizer is fundamentally different from the conventinal ones. It can function in a wide frequency range with high performance and the size can be made very compact, which renders it useful as a micropolarizer…

Materials ScienceSoft Condensed Matter

Perpendicular transport and magnetization processes in magnetic multilayers with strongly and weakly coupled magnetic layers

M. Zwierzycki、S. Krompiewski1999-04-07arXiv

Within the framework of a two-band tight-binding model, we have performed calculations of giant magnetoresistance, exchange coupling and thermoelectric power (TEP) for a system consisting of three magnetic layers separated by two non-magnetic spacers with the first two magnetic layers strongly antiferromagnetically ex…

Mesoscale and Nanoscale PhysicsMaterials Science

Fluorescence Properties of Poly(ethylene terephthalate-co-2,6-naphthalene dicarboxylate) with Naphthalene Contents Ranging from 0.01 to 100 mol

Allan S. Jones、Todd J. Dickson、Bruce E. Wilson 等 4 位作者1999-04-06Macromolecules

Several samples of poly(ethylene terephthalate- co -2,6-naphthalene dicarboxylate) were synthesized with different contents of dimethyl-2,6-naphthalene dicarboxylate (DMN). The polymer samples were ground into powders, and steady-state and time-resolved fluorescence measurements were carried out on these copolymers. T…

Organic Light-Emitting Diodes ResearchPhotochemistry and Electron Transfer StudiesLuminescence and Fluorescent Materials

Effects of Molecular Structure of Modifiers on the Thermodynamics of Phenolic Blends: An Entropic Factor Complementing PCAM

Hew-Der Wu、Peter P. Chu、M. Chen-Chi 等 4 位作者1999-04-06Macromolecules

Different thermodynamics in phenolic blends with different polymeric modifiers, i.e., phenoxy, poly(decamethylene adipate), poly(ethylene oxide), and poly(vinyl alcohol), calculated by the Painter and Coleman association model (PCAM) are examined. The thermodynamics is calculated based upon the equilibrium constants d…

Polymer crystallization and propertiesMaterial Dynamics and PropertiesNMR spectroscopy and applications

Small-Angle Neutron Scattering and Surface Force Investigations of Poly(amido amine) Dendrimer with Hydroxyl End Groups

Toyoko Imae、Katsuya Funayama、Keigo Aoi 等 6 位作者1999-04-06Langmuir

Atomic force microscopic image on mica substrate, which was dipped for 10 min in an aqueous solution of fifth-generation poly(amido amine) dendrimer with hydroxyl end groups, displayed a flatter texture of dendrimer-adsorbed surface. On the external contrast variation of small-angle neutron scattering for aqueous dend…

Advanced Polymer Synthesis and CharacterizationPolymer Surface Interaction StudiesDendrimers and Hyperbranched Polymers