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第 181019 / 189043 页 · 当前展示 3,620,361–3,620,380 / 3,780,845 条匹配结果 · 摘要仅作预览

Electronic Structure and Nature of the Ground State of the Mixed-Valence Binuclear Tetra(μ-1,8-naphthyridine-N,N′)-bis(halogenonickel) Tetraphenylborate Complexes: Experimental and DFT Characterization

Alessandro Bencini、Elisabetta Berti、Andréa Caneschi 等 6 位作者2002-08-16Chemistry - A European Journal

The ground state electronic structure of the mixed-valence systems [Ni(2)(napy)(4)X(2)](BPh(4)) (napy=1,8-naphthyridine; X=Cl, Br, I) was studied with combined experimental (X-ray diffraction, temperature dependence of the magnetic susceptibility, and high-field EPR spectroscopy) and theoretical (DFT) methods. The zer…

Metal complexes synthesis and propertiesMagnetism in coordination complexesLanthanide and Transition Metal Complexes

Chiral Templating of SilicaâLipid Lamellar Mesophase with Helical Tubular Architecture We thank the University of Bristol and EPSRC for financial support, and Dr. S. A. Davis and Dr. C. Göltner for helpful discussions.

Annela M. Seddon、Harish M. Patel、Sandra L. Burkett 等 4 位作者2002-08-16Angewandte Chemie

Eine lamellare Hybrid-Mesostruktur mit polymerisierbaren Diacetylengruppen wird bei der In-situ-Synthese von Siliciumdioxid durch saure Hydrolyse und Kondensation von Tetraethylorthosilicat (TEOS) in Gegenwart von 1,2-Bis(10,12-tricosadiinonyl)-sn-glycero-3-phosphatidylcholin (DC8,9PC) gebildet. Diese Mesostruktur lag…

Mesoporous Materials and CatalysisPorphyrin and Phthalocyanine ChemistrySupramolecular Self-Assembly in Materials

Template-Synthesized Nanotubes for Chemical Separations and Analysis

Marc Wirtz、Matthew Parker、Yoshio Kobayashi 等 4 位作者2002-08-16Chemistry - A European Journal

We have developed a new class of synthetic membranes that consist of a porous polymeric support that contains an ensemble of gold nanotubes that span the thickness of the support membrane. The support is a commercially-available microporous polycarbonate filter with cylindrical nanoscopic pores. The gold nanotubes are…

Carbon Nanotubes in CompositesNanotechnology research and applications

Phonon anomalies in the two phases of the low-dimensional spin compound(VO)2P2O7

Uwe Kuhlmann、C. Thomsen、A. Prokofiev 等 8 位作者2002-08-16Physical review. B, Condensed matter

We studied the temperature and pressure dependence of the phonons of the two different phases of $(\mathrm{VO}{)}_{2}{\mathrm{P}}_{2}{\mathrm{O}}_{7},$ the ambient (AP) and the high-pressure (HP) phase, by polarized Raman spectroscopy. Most modes in the lower-symmetry AP phase are split compared to the higher-symmetry…

Physics of Superconductivity and MagnetismTransition Metal Oxide NanomaterialsAdvanced Condensed Matter Physics

Phonon dispersions in niobium determined by x-ray transmission scattering

Martin V. Holt、Peter Czoschke、Hawoong Hong 等 6 位作者2002-08-16Physical review. B, Condensed matter

Quasielastic x-ray scattering from thermally populated phonons in crystalline niobium was recorded using a charge-coupled device over a large angular range. The patterns, displayed on a logarithmic intensity scale, reveal rich features. Theoretical patterns based on a lattice dynamics calculation are generated, and a…

High-pressure geophysics and materialsThermal properties of materialsNuclear Physics and Applications

Thermal Characterization of Adsorbed Polystyrene Using Modulated Differential Scanning Calorimetry

Crystal Porter、Frank D. Blum2002-08-16Macromolecules

The glass transition behavior of dried polystyrene (PS) samples adsorbed on silica, originally cast from carbon tetrachloride, has been studied using modulated differential scanning calorimetry (MDSC). The adsorbed amounts of the polymers on silica were very small, ranging from about 2 to 0.4 mg polymer/m 2 silica. Th…

Polymer crystallization and propertiesMaterial Dynamics and PropertiesPolymer Nanocomposites and Properties

A hydrothermal post-synthesis route for the preparation of high quality MCM-48 silica with a tailored pore size

Jihong Sun、Marc‐Olivier Coppens2002-08-16Journal of Materials Chemistry

A post-synthesis hydrothermal restructuring method is introduced as a convenient route to synthesize high quality MCM-48 silica with controllable pore size. Using tetraethyl orthosilicate as the silica source and cetyltrimethylammonium bromide (CTAB) as the template, the pore size could be tailored from 2.6 to 4.2 nm…

Catalytic Processes in Materials ScienceZeolite Catalysis and SynthesisMesoporous Materials and Catalysis

Adsorption State and Molecular Orientation of Ammonia on ZnO(1010) Studied by Photoelectron Spectroscopy and near-Edge X-ray Absorption Fine Structure Spectroscopy

K. Ozawa、Takuya Hasegawa、K. Edamoto 等 5 位作者2002-08-16The Journal of Physical Chemistry B

The adsorption state of ammonia (NH 3 ) on the ZnO(101̄0) surface has been investigated using photoelectron spectroscopy (PES) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The core-level and valence-band PES measurements reveal that ammonia adsorbs molecularly via its N atom on ZnO(101̄0) and t…

ZnO doping and propertiesCatalytic Processes in Materials ScienceElectron and X-Ray Spectroscopy Techniques

Are metastable, precrystallisation, density-fluctuations a universal phenomena?

Ellen L. Heeley、C. Kit Poh、Wu Li 等 13 位作者2002-08-16Faraday Discussions

In-situ observations of crystallisation in minerals and organic polymers have been made by simultaneous, time-resolved small angle X-ray scattering (SAXS) and wide angle X-ray scattering (WAXS) techniques. In isotactic polypropylene slow quiescent crystallisation shows the onset of large scale ordering prior to crysta…

Polymer crystallization and propertiesPolymer Nanocomposites and PropertiesBlock Copolymer Self-Assembly

Conjugated polyrotaxanes: improvement of the polymer properties by using sterically hindered coordinating units

Jean‐Pierre Sauvage、Jean‐Marc Kern、G rard Bidan 等 5 位作者2002-08-16New Journal of Chemistry

A new conjugated copper-complexed polyrotaxane has been prepared by electropolymerization of a thiophene derivative; the rings are threaded onto a multi-1,10-phenanthroline (phen) axle, copper(I) acting as a template. The presence of CH3 groups ortho to the nitrogen atoms of the phen nuclei belonging to the conjugated…

Organic Electronics and PhotovoltaicsConducting polymers and applicationsLuminescence and Fluorescent Materials

Pressure-induced energy transfer processes betweenSm3+ions in lithium fluoroborate glasses

V. Lavı́n、Inocencio R. Martín、C.K. Jayasankar 等 4 位作者2002-08-16Physical review. B, Condensed matter

Fluorescence decay curves for the ${}^{4}{\stackrel{\ensuremath{\rightarrow}}{{G}_{5/2}}}^{6}{H}_{7/2}$ transition of ${\mathrm{Sm}}^{3+}$ ions in lithium fluoroborate glasses for different lanthanide concentrations have been measured as a function of pressure up to 21 GPa at room temperature. At ambient conditions, f…

Luminescence Properties of Advanced MaterialsGlass properties and applicationsLanthanide and Transition Metal Complexes

Small-angle neutron scattering study of the temperature-dependent attractive interaction in denseL64copolymer micellar solutions and its relation to kinetic glass transition

Wei‐Ren Chen、Sow‐Hsin Chen、Francesco Mallamace2002-08-16Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics

We made small-angle neutron scattering (SANS) study of a Pluronic L64 micellar system in aqueous solution at high polymer concentrations (wt %), 35%<c<53%, in a temperature range where a kinetic glass transition has been observed by photon correlation spectroscopy and zero shear viscosity measurements. We analyze SANS…

Phase Equilibria and ThermodynamicsMaterial Dynamics and PropertiesSurfactants and Colloidal Systems

Controlled Fabrication of Large-Scale Aligned Carbon Nanofiber/Nanotube Patterns by Photolithography

Shaoming Huang、Liming Dai、Ada Mau2002-08-16Advanced Materials

Large-scale aligned carbon nanofiber/nanotube patterns have been fabricated by a feasible and inexpensive direct photolithography technique using ordinary black-and-white film as a photomask. Using a calcination/reduction protocol, transition metal salts in the photoresist are transformed to metallic dots, which act a…

Carbon Nanotubes in Composites

Direct Electrochemistry of Cytochrome c at Nanocrystalline Boron-Doped Diamond

Shannon Haymond、Ǵerald Babcock、Greg M. Swain2002-08-16Journal of the American Chemical Society

Direct electron transfer of horse heart cytochrome c is measured at a nanocrystalline boron-doped diamond thin-film electrode. A quasi-reversible, diffusion-controlled cyclic voltammetric response is observed for untreated diamond. The peak currents change linearly with the concentration, and importantly, there is no…

Diamond and Carbon-based Materials ResearchForce Microscopy Techniques and ApplicationsElectrochemical Analysis and Applications

On the extended recrystallisation of mesoporous silica: characterisation of restructured pure silica MCM-41

Robert Mokaya2002-08-16Journal of Materials Chemistry

Mesoporous silica MCM-41 may be restructured by performing secondary synthesis (i.e., recrystallisation) in which calcined MCM-41 is used as silica source. The influence of a number of factors on the recrystallisation has been investigated. The factors investigated are, (1) the time allowed for hydrothermal recrystall…

Zeolite Catalysis and SynthesisMesoporous Materials and CatalysisLayered Double Hydroxides Synthesis and Applications

Partitioning of Polymers into Pores near the Critical Adsorption Point

Yingchuan Gong、Yongmei Wang2002-08-16Macromolecules

We have examined the critical adsorption transition for a nonreversible random walk chain (NRRW) and a self-avoiding walk chain (SAW) at the surface and have identified the critical adsorption point. We then examine the partition coefficient of a NRRW chain and a SAW chain confined in a slit with two adsorbing walls n…

Material Dynamics and PropertiesSurfactants and Colloidal SystemsAnalytical Chemistry and Chromatography

(RO)2Ta[tris(2-oxy-3,5-dimethylbenzyl)amine]: Structure and Lactide Polymerization Activities

Youngjo Kim、Pramesh N. Kapoor、John G. Verkade2002-08-16Inorganic Chemistry

The novel atrane-like six-coordinate (RO)(2)TaL complexes [where R = Me or Et and L = tris(2-oxy-3,5-dimethylbenzyl)amine] containing three six-membered rings have been synthesized and characterized. The R = Me complex is the first group 5 representative of this class of compounds structurally characterized by X-ray m…

Organometallic Complex Synthesis and Catalysisbiodegradable polymer synthesis and propertiesCarbon dioxide utilization in catalysis

Influence of Dextran on the Phase Behavior of Suspensions of Cellulose Nanocrystals

Catherine D. Edgar、Derek G. Gray2002-08-16Macromolecules

Acid hydrolysis of cellulose fibers produces suspensions of colloidal cellulose nanocrystals. At low concentrations these suspensions are isotropic, while at high concentrations the cellulose rods spontaneously organize into a chiral nematic liquid crystal phase. We have studied the effect of adding high molecular wei…

Liquid Crystal Research AdvancementsAdvanced Cellulose Research StudiesElectrohydrodynamics and Fluid Dynamics

Fabrication of 2D Gold Nanowires by Self-Assembly of Gold Nanoparticles on Water Surfaces in the Presence of Surfactants

Tue Hassenkam、Kasper Nørgaard、Lars Iversen 等 6 位作者2002-08-16Advanced Materials

Self-assembly of metallic nanostructures using 2D templates consisting of surfactant systems at the air/water interface is demonstrated (see Figure). The morphology of the resulting nanostructures can be partially controlled by adjusting parameters such as the molecular structure of the surfactant, the chemical proper…

Gold and Silver Nanoparticles Synthesis and ApplicationsPolymer Surface Interaction StudiesPickering emulsions and particle stabilization

A Structural and Functional Model of Galactose Oxidase: Control of the One-Electron Oxidized Active Form through Two Differentiated Phenolic Arms in a Tripodal Ligand

Fabrice Thomas、Gisà ̈le Gellon、Isabelle Gautier‐Luneau 等 5 位作者2002-08-16Angewandte Chemie International Edition

The axial phenol group is protonated and the equatorial phenoxyl group antiferromagnetically coupled to the cupric center in the complex [CuII(LH)(OAc)].+ (see picture), which can be considered as both a structural and functional model of galactose oxidase. This complex reproduces the features of the enzyme chemistry.…

Metal complexes synthesis and propertiesMagnetism in coordination complexesElectron Spin Resonance Studies