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Axial Coordination and Conformational Heterogeneity of Nickel(II) Tetraphenylporphyrin Complexes with Nitrogenous Bases

Song‐Ling Jia、Walter Jentzen、Mayou Shang 等 7 位作者1998-07-31Inorganic Chemistry

Axial ligation of nickel(II) 5,10,15,20-tetraphenylporphyrin (NiTPP) with pyrrolidine or piperidine has been investigated using X-ray crystallography, UV-visible spectroscopy, resonance Raman spectroscopy, and molecular mechanics (MM) calculations. By varying the pyrrolidine concentration in dichloromethane, distinct…

Metal complexes synthesis and propertiesPorphyrin and Phthalocyanine ChemistryPhotochemistry and Electron Transfer Studies

Beta-integers as natural counting systems for quasicrystals

Č. Burdík、Ch Frougny、Jean‐Pierre Gazeau 等 4 位作者1998-07-31Journal of Physics A Mathematical and General

Recently, discrete sets of numbers, the -integers , have been proposed as numbering tools in quasicrystalline studies. Indeed, there exists a unique numeration system based on the irrational in which the -integers are all real numbers with no fractional part. These -integers appear to be quite appropriate for describi…

Quasicrystal Structures and PropertiesMineralogy and Gemology Studies

Multi-Atom Resonant Photoemission: A Method for Determining Near-Neighbor Atomic Identities and Bonding

A. Kay、Elke Arenholz、Sungkwang Mun 等 8 位作者1998-07-31Science

Measurements and theoretical calculations are reported for an interatomic multi-atom resonant photoemission (MARPE) effect that permits direct determination of near-neighbor atomic identities (atomic numbers). MARPE occurs when the photon energy is tuned to a core-level absorption edge of an atom neighboring the emitt…

X-ray Spectroscopy and Fluorescence AnalysisElectron and X-Ray Spectroscopy TechniquesElectronic and Structural Properties of Oxides

Refolding of Escherichia coli produced membrane protein inclusion bodies immobilised by nickel chelating chromatography

Hans Rogl、Kirstin Kosemund、Werner Kühlbrandt 等 4 位作者1998-07-31FEBS Letters

Two distinctly different membrane proteins, which produced inclusion bodies in Escherichia coli, have been refolded to reconstitute properties appropriate to their native counterparts. The method employed utilises nickel chelating chromatography, where the solubilised inclusion bodies bind, refold and elute. Our aims…

Bacterial Genetics and BiotechnologyRNA and protein synthesis mechanismsEnzyme Structure and Function

Dicarboxylic Oligopeptide Bolaamphiphiles: Proton-Triggered Self-Assembly of Microtubes with Loose Solid Surfaces

Masaki Kogiso、Satomi Ohnishi、Kiyoshi Yase 等 5 位作者1998-07-31Langmuir

A new family of oligopeptide-based bolaamphiphiles, glycylglycine- ( 1a − h ), glycylglycylglycine- ( 2a − b ), sarcosylsarcosine- ( 3 ), l -prolyl- l -proline- ( 4 ), glycylsarcosylsarcosine- ( 5 ), and glycyl- l -prolyl- l -proline ( 6 )-based bolaamphiphiles with a dicarboxylic headgroup at each end, has been synth…

Supramolecular Chemistry and ComplexesChemical Synthesis and AnalysisSupramolecular Self-Assembly in Materials

Ab initio pseudopotentials for electronic structure calculations of poly-atomic systems using density-functional theory

Martin Fuchs、Matthias Scheffler1998-07-31arXiv

The package fhi98PP allows one to generate norm-conserving pseudopotentials adapted to density-functional theory total-energy calculations for a multitude of elements throughout the periodic table, including first-row and transition metal elements. The package also facilitates a first assessment of the pseudopotential…

Materials Science

Theory of the "honeycomb chain-channel" reconstruction of Si(111)3x1

Steven C. Erwin、Hanno H. Weitering1998-07-31arXiv

First-principles electronic-structure methods are used to study a structural model for Ag/Si(111)3x1 recently proposed on the basis of transmission electron diffraction data. The fully relaxed geometry for this model is far more energetically favorable than any previously proposed, partly due to the unusual formation…

Materials Science

Core Shell Inversion during Nucleation and Growth of Bimetallic Pt/Ru Nanoparticles

Michael S. Nashner、Anatoly I. Frenkel、David M. Somerville 等 6 位作者1998-07-31Journal of the American Chemical Society

The reductive condensation of a carbon-supported molecular cluster precursor, PtRu 5 C(CO) 16, into a bimetallic nanoparticle has been followed by using in situ extended X-ray absorption fine structure spectroscopy, temperature-programmed desorption, and scanning transmission electron microscopy. The data reveal that…

Electrocatalysts for Energy ConversionCatalytic Processes in Materials ScienceQuantum Dots Synthesis And Properties

Porous monodisperse poly(divinylbenzene) microspheres by precipitation polymerization

Wenhui Li、Harald D. H. Stöver1998-07-30Journal of Polymer Science Part A Polymer Chemistry

The precipitation polymerization of commercial divinylbenzene in acetonitrile containing up to 40 vol. % toluene or other cosolvents is shown to produce novel porous monodisperse poly(divinylbenzene) microspheres. These microspheres have diameters between 4 and 7 μm, total pore volumes of up to 0.52 cm3/g, and surface…

Mesoporous Materials and CatalysisMembrane Separation and Gas TransportCovalent Organic Framework Applications

Thermodynamic properties of novolac-type phenolic resin blended with poly(ethylene oxide)

Peter P. Chu、Hew-Der Wu、Chih-Tsung Lee1998-07-30Journal of Polymer Science Part B Polymer Physics

The thermodynamic properties of novolac type phenolic resin blended with poly(ethylene oxide) (PEO) were investigated by the Painter–Coleman association model (PCAM). Equilibrium constants and enthalpy corresponding to the interaction between phenolic and poly(ethylene oxide) were calculated from the Fourier transform…

Polymer crystallization and propertiesEpoxy Resin Curing ProcessesSynthesis and properties of polymers

Crystallization kinetics of a thermotropic liquid crystalline polyimide derived from 1,3-bis[4-(4?-aminophenoxy) cumyl] benzene

Songlin Liu、Tai‐Shung Chung、Lining Lu 等 6 位作者1998-07-30Journal of Polymer Science Part B Polymer Physics

We have studied the nonisothermal and isothermal crystallization kinetics of an aromatic thermotropic liquid crystalline polyimide synthesized from 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA) and 1,3-bis[4-(4′-aminophenoxy) cumyl] benzene (BACB) by means of differential scanning calorimetry (DSC). Polarized ligh…

Liquid Crystal Research AdvancementsEpoxy Resin Curing ProcessesSynthesis and properties of polymers

Effects of CO2 conditioning on sorption, dilation, and transport properties of polysulfone

Jinsheng Wang、Yoshinori Kamiya、Yasutoshi Naito1998-07-30Journal of Polymer Science Part B Polymer Physics

Sorption, dilation, and diffusion behaviors were studied for the system of polysulfone/CO2 with regard to the effects of CO2 conditioning, i.e., exposure to high-pressure CO2. Concurrent measurements of solubility, dilation, and diffusivity were performed for polysulfone films before and after the conditioning at 25 a…

Polymer crystallization and propertiesMembrane Separation and Gas TransportPolymer Foaming and Composites

Comparison of ultrasonic shear wave and dynamic-mechanical measurements in acrylic-type copolymers

I. Alig、S. Tadjbakhsch、A. Zosel1998-07-30Journal of Polymer Science Part B Polymer Physics

An ultrasonic shear wave reflection method was applied to study film formation and temperature dependence of the complex shear modulus (G*G′ + iG″) in different amorphous films made of aqueous dispersions of acrylic-type copolymers. The data are compared with dynamic-mechanical measurements in the low frequency range…

Material Dynamics and PropertiesPolymer Nanocomposites and PropertiesRheology and Fluid Dynamics Studies

Mechanistic Aspects of the Electrochemical Reduction of 7,7,8,8-Tetracyanoquinodimethane in the Presence of Mg2+ or Ba2+

Munetaka Oyama、Richard D. Webster、Marco F. Suárez 等 6 位作者1998-07-30The Journal of Physical Chemistry B

The effect of aggregation of Mg 2+ or Ba 2+ (M 2+ ) and electrochemically generated reduced forms of 7,7,8,8-tetracyanoquinodimethane (TCNQ) in acetonitrile solution was studied by voltammetric and chronoamperometric techniques, the electrochemical quartz crystal microbalance (EQCM), ESR spectroscopy, and atomic force…

Molecular Junctions and NanostructuresElectrochemical Analysis and ApplicationsOrganic and Molecular Conductors Research

Asymmetrization effects on structures and populations of the ground state of dipolar donor-acceptor-substituted molecular organic NLO materials

Rainer Glaser、Grace Shiahuy Chen1998-07-30Journal of Computational Chemistry

Asymmetric donor–acceptor-substituted π-conjugated systems with low dipole moments and structural components that favor parallel alignment of neighboring molecules are potential molecular organic materials with nonlinear optical properties for which near prefect dipole parallel alignment is possible. The asymmetrical…

Crystallography and molecular interactionsNonlinear Optical Materials ResearchOrganic and Molecular Conductors Research

High-strain tensile deformation of a sphere-forming triblock copolymer/mineral oil blend

Elisabeth Prasman、Edwin L. Thomas1998-07-30Journal of Polymer Science Part B Polymer Physics

Films of a blend of styrene–isoprene triblock copolymer and mineral oil have been simple-cast and roll-cast from a toluene solution. Their microstructure has been analyzed by transmission electron microscopy and small-angle X-ray scattering. The blend formed polystyrene spheres arranged on a body-centered cubic lattic…

Polymer crystallization and propertiesPolymer Nanocomposites and PropertiesPolymer composites and self-healing

Multiple melting endotherms in isothermally melt-crystallized poly(butylene terephthalate)

Hong Gyun Kim、Richard E. Robertson1998-07-30Journal of Polymer Science Part B Polymer Physics

The melting behavior of poly(butylene terephthalate) crystallized isothermally for various times was examined using differential scanning calorimetry. After short crystallization times, the DSC analysis gave two melting peaks, but after longer times, the analysis gave three peaks. The latter triplet of DSC peaks can b…

Polymer crystallization and propertiesbiodegradable polymer synthesis and propertiesMicroplastics and Plastic Pollution

Optical anisotropy of a photoreacted side-chain liquid-crystalline polymer induced by linearly polarized UV light

Nobuhiro Kawatsuki、Hirohumi Takatsuka、Tohei Yamamoto 等 4 位作者1998-07-30Journal of Polymer Science Part A Polymer Chemistry

Linearly polarized (LP) UV photoreaction of a photo-crosslinkable side-chain liquid-crystalline polymer (SLCP) containing photoreactive cinnamoyl and biphenyl mesogenic groups (1) was studied. The optical anisotropy of the polymer film was induced by the LP-UV photoreaction and was investigated by the temperature-cont…

Liquid Crystal Research AdvancementsSemiconductor Lasers and Optical DevicesSynthesis and properties of polymers

Highly Ordered Poly(cyclopentabithiophenes) Functionalized with Crown-Ether Moieties for Lithium- and Sodium-Sensing Electrodes

Franco Sannicolò、Elisabetta Brenna、Tiziana Benincori 等 7 位作者1998-07-30Chemistry of Materials

Functionalized cyclopentadithiophenes 2 and 3 were synthesized and polymerized by anodic coupling, in acetonitrile solution, in the presence of 0.1 M tetraethylammonium perchlorate as supporting electrolyte. The former carries a 16-crown-5-ether ring coplanar to the bithiophene moiety, while a perpendicular 15-crown-5…

Conducting polymers and applicationsElectrochemical Analysis and ApplicationsAnalytical Chemistry and Sensors

Preparation and properties of poly (styrene-co-maleic anhydride) / silica hybrid materials by the in situ sol-gel process

Wen Zhou、Jian Hua Dong、Kun Yun Qiu 等 4 位作者1998-07-30Journal of Polymer Science Part A Polymer Chemistry

Poly(styrene-co-maleic anhydride)/silica hybrid material has been successfully prepared from styrene–maleic anhydride copolymer and tetraethoxysilane (TEOS) in the presence of a coupling agent (3-aminopropyl)triethoxysilane (APTES) by an in situ sol–gel process. It was observed that the gel time of sol–gel solution wa…

Polymer Nanocomposites and PropertiesMesoporous Materials and CatalysisSilicone and Siloxane Chemistry