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Crystals of Tryptophan Indole-Lyase and Tyrosine Phenol-Lyase Form Stable Quinonoid Complexes

Robert S. Phillips、Tatyana V. Demidkina、Lyudmila N. Zakomirdina 等 6 位作者2002-06-01Journal of Biological Chemistry

The binding of substrates and inhibitors to wild-type Proteus vulgaris tryptophan indole-lyase and to wild type and Y71F Citrobacter freundii tyrosine phenol-lyase was investigated in the crystalline state by polarized absorption microspectrophotometry. Oxindolyl-lalanine binds to tryptophan indole-lyase crystals to a…

Enzyme Structure and FunctionPolyamine Metabolism and ApplicationsPharmacological Effects of Natural Compounds

Synthesis and Characterization of Fe- or Cu-Substituted Molybdenum-Enriched Tungstodiphosphates

Robila Belghiche、Roland Contant、Yu Wei Lu 等 7 位作者2002-06-01European Journal of Inorganic Chemistry

Stereospecific routes were followed to synthesize five new Fe3+ and Cu2+-substituted Mo-enriched Dawson-type heteropolyanions as aqueous soluble potassium salts: α2-K7[Fe(OH2)P2W12Mo5O61] and α2-K7[Fe(OH2)P2W13Mo4O61], α1- and α2-K8[Cu(OH2)P2W12Mo5O61] and α2-K8[Cu(OH2)P2W13Mo4O61]. The substituted species as well as…

Polyoxometalates: Synthesis and ApplicationsChemical Synthesis and ReactionsChemical Synthesis and Characterization

Thiosilicate der Selten-Erd-Elemente: I. Die isotypen Verbindungen KCe[SiS4] und Eu2[SiS4]

Ingo Hartenbach、Thomas Schleid2002-06-01Zeitschrift für anorganische und allgemeine Chemie

Die beiden isotypen Thiosilicate KCe[SiS4] (a = 649, 15(6), b = 656, 18(6), c = 863, 96(8) pm, β = 107, 531(9)°) und Eu2[SiS4] (a = 651, 71(6), b = 659, 54(6), c = 821, 93(8) pm, β = 108, 437(9)°) kristallisieren monoklin in der Raumgruppe P21/m mit Z = 2. Bei der Umsetzung von KCl, Ce2S3 und SiS2 im Verhältnis 1 : 1…

Crystal Structures and PropertiesChemical Synthesis and CharacterizationInorganic Chemistry and Materials

Inhibition of the corrosion of low carbon steel in acidic solution by selected quaternary ammonium compounds

Gözen Bereket、A. Yurt2002-06-01Anti-Corrosion Methods and Materials

Potentiodynamic polarisation studies were carried out on the inhibition of low carbon steel in 0.1M hydrochloric acid solution over the temperature range 20‐60°C at different inhibitor concentrations by various quaternary ammonium salts and cationic surfactants. The inhibitors examined were tetraethyl ammonium chlorid…

Corrosion Behavior and InhibitionConcrete Corrosion and DurabilityMaterial Properties and Failure Mechanisms

Natural Ageing of Automotive Polymer Components: Characterisation of New and Used Poly(propylene) based Car Bumpers

Maria Paola Luda Di Cortemiglia、G. Ragosta、Pellegrino Musto 等 7 位作者2002-06-01Macromolecular Materials and Engineering

The chemical and morphological structure of new and post-consumer ten years old poly(propylene) based car bumpers has been investigated and their mechanical properties have been correlated to the chemical and physical degradation of the material. Poly(propylene) matrix and a rubbery ethylene-propylene phase were the c…

Polymer crystallization and propertiesbiodegradable polymer synthesis and propertiesPolymer Foaming and Composites

Chlorite composition and geothermometry: a comparative HRTEM/AEM-EMPA-XRD study of Cambrian basic lavas from the Ossa Morena Zone, SW Spain

Aurora López-Munguira、Fernando Nieto、Diego Morata2002-06-01Clay Minerals

Abstract Chlorites from Cambrian basaltic vesicular lavas, characterized by relatively high X c (0.81-0.98), gave temperatures of formation of 285 to 350 ° C (Cathelineau's empirical geothermometer). Both the X c and temperature calculations gave results which were too high for the diagenetic conditions indicated by t…

Geological and Geochemical AnalysisGeochemistry and Elemental AnalysisClay minerals and soil interactions

Monolith Reactor for the Dehydrogenation of Ethylbenzene to Styrene

Wei Liu、William P. Addiego、Charles M. Sorensen 等 4 位作者2002-06-01Industrial & Engineering Chemistry Research

Honeycomb-shaped monolithic catalysts offer an attractive solution to the long-standing problem of balancing the reactor pressure drop with mass transfer in fixed-bed reactors. This approach is discussed in detail in this paper based on experimental and modeling data for the dehydrogenation of ethylbenzene to styrene.…

Catalytic Processes in Materials ScienceCatalysts for Methane ReformingCatalysis and Oxidation Reactions

One transistor ferroelectric memory with Pt/Pb/sub 5/Ge/sub 3/O/sub 11//Ir/poly-Si/SiO/sub 2//Si gate-stack

Tingkai Li、Sheng Teng Hsu、Bruce Ulrich 等 6 位作者2002-06-01IEEE Electron Device Letters

One transistor ferroelectric nonvolatile memory with gate stack of Pt/Pb5Ge3O/sub 11//lr/poly-Si/SiO2/Si was successfully fabricated. This device features a saturated memory window of 3 V at a programming voltage of higher than 3 V from C-V and I-V measurements. The memory window decays rapidly within 10 seconds after…

Ferroelectric and Piezoelectric MaterialsSemiconductor materials and devicesAcoustic Wave Resonator Technologies

Planar waveguides in multicomponent glasses fabricated by field-driven differential drift of cations

A. L. R. Brennand、James S. Wilkinson2002-06-01Optics Letters

The fabrication of planar waveguides by a constant-current thermal poling procedure in multicomponent glasses rich in alkali or alkaline earth ions is described. Near the anode, the dc electric field applied to the substrate separates the mobile cations into regions according to their mobility. Each region presents a…

Photonic and Optical DevicesGlass properties and applicationsPhotorefractive and Nonlinear Optics

Surface modification of Mesoporous Silica to Control the States of Tris(2,2′-bipyridine)ruthenium(II) Cations

Makoto Ogawa、Kazuyuki Kuroda、Tomoyuki Nakamura2002-06-01Chemistry Letters

Abstract The adsorption and immobilization of tris(2,2′-bipyridine)ruthenium(II) ([Ru(bpy)3]2+) in mesoporous silicas (C18-FSM) modified by the introduction of aluminum as well as sulfonic acid groups were investigated. The complex was immobilized by the cooperative effects of electrostatic interactions between [Ru(bp…

Mesoporous Materials and CatalysisPorphyrin and Phthalocyanine ChemistryLanthanide and Transition Metal Complexes

Comparative Study of an Anisotropic Polymer Layer by Infrared Spectroscopic Techniques

Karsten Hinrichs、D. Tsankov、E. H. Korte 等 6 位作者2002-06-01Applied Spectroscopy

Infrared spectroscopic ellipsometry (IRSE), reflection absorption IR spectroscopy (RAIRS), IR transmission spectroscopy, and best-fit calculations are applied in a cooperative study to determine the anisotropic optical properties of a thin polyimide layer in the spectral range 4000–500 cm −1 . The employed anisotropic…

Liquid Crystal Research AdvancementsSpectroscopy and Chemometric AnalysesNonlinear Optical Materials Research

Evidence for transient kinetics of nucleation as responsible for the isothermal transformation of supercooled liquid into the glacial state of triphenyl phosphite

Alain Hédoux、Yannick Guinet、Michel Foulon 等 4 位作者2002-06-01The Journal of Chemical Physics

The first-order transformation of the supercooled liquid into the glacial state of triphenyl phosphite was investigated by differential scanning calorimetry (DSC) using two different thermal procedures. In the first procedure the transformation was analyzed by heating run DSC experiments. The glaciation process was in…

Liquid Crystal Research AdvancementsMaterial Dynamics and PropertiesThermal and Kinetic Analysis

Measurement of space charge in XLPE insulation under 50 Hz ac electric stresses using the LIPP method

Y.F.F. Ho、G. Chen、A.E. Davies 等 7 位作者2002-06-01IEEE Transactions on Dielectrics and Electrical Insulation

Space charge is believed to play an important role in ac electrical ageing of polymeric insulation, particularly where electrical treeing is the dominant cause of premature failure. The majority of work to date has been on the space charge characteristics under dc electric stresses, whereas work on the dynamics and th…

High voltage insulation and dielectric phenomenaLightning and Electromagnetic PhenomenaPower Transformer Diagnostics and Insulation

Exchangeable potassium in soil as indicator of potassium status in an organic crop rotation on loamy sand

Margrethe Askegaard、Jørgen Eriksen2002-06-01Soil Use and Management

Abstract. In organic agriculture, where K may be a limited resource, reliable tools are important in the assessment of K availability in the soil in order to avoid K deficiency. We investigated the effect of four organic farming systems on the exchangeable K in the plough layer of a six‐course crop rotation from 1994…

Soil and Unsaturated FlowSoil and Water Nutrient DynamicsClay minerals and soil interactions

Isocitrate Binding at Two Functionally Distinct Sites in Yeast NAD+-specific Isocitrate Dehydrogenase

An-Ping Lin、Lee McAlister-Henn2002-06-01Journal of Biological Chemistry

Yeast NAD(+)-specific isocitrate dehydrogenase (IDH) is an octamer containing two types of homologous subunits. Ligand-binding analyses were conducted to examine effects of residue changes in putative catalytic and regulatory isocitrate-binding sites respectively contained in IDH2 and IDH1 subunits. Replacement of hom…

Protein Structure and DynamicsEnzyme Structure and FunctionBiochemical and Molecular Research

Surface Morphology Evolution of Thin Triblock Copolymer Films during Spin Coating

Xue Li、Yanchun Han、Lijia An2002-06-01Langmuir

The surface morphology evolution of thin poly(styrene- block -ethylene/butylenes- block -styrene) (SEBS) triblock copolymer films as a function of the copolymer concentration was investigated by means of dynamic mode atomic force microscopy. At a relatively low copolymer concentration (0.025% w/v), the periodically or…

Polymer Surface Interaction StudiesBlock Copolymer Self-AssemblyFluid Dynamics and Thin Films

Morphology of a Poly(imide siloxane) Segmented Copolymer/Silica Hybrid Composite

Ho Bum Park、Jaehoon Kim、Jang Ki Kim 等 4 位作者2002-06-01Macromolecular Rapid Communications

The role of polydimethylsiloxane (PDMS) as a compatibilizer of polyimide/silica hybrid composites was investigated. Introduction of PDMS into a polyimide matrix retards the phase separation of hybrid composites and also prevents the formation of high-molecular-weight silicate. PDMS interacts with silica because of the…

Synthetic Organic Chemistry MethodsSynthesis and properties of polymersSilicone and Siloxane Chemistry

Cloning and Characterization of Methenyltetrahydrofolate Synthetase from Saccharomyces cerevisiae

William B. Holmes、Dean R. Appling2002-06-01Journal of Biological Chemistry

The folate derivative 5-formyltetrahydrofolate (folinic acid; 5-CHO-THF) was discovered over 40 years ago, but its role in metabolism remains poorly understood. Only one enzyme is known that utilizes 5-CHO-THF as a substrate: 5,10-methenyltetrahydrofolate synthetase (MTHFS). A BLAST search of the yeast genome using th…

Folate and B Vitamins ResearchEnzyme Structure and FunctionBiochemical and Molecular Research

Grain Growth and Twin Formation in 0.74PMN·0.26PT

Jay S. Wallace、Jong‐Moo Huh、John E. Blendell 等 4 位作者2002-06-01Journal of the American Ceramic Society

The mechanisms controlling normal and exaggerated grain growth in lead magnesium niobate–lead titanate (PMN–PT) ceramics have been investigated by varying the PbO‐based liquid‐phase volume fraction from 0.03 to 0.6 and sintering temperature from 900° to 1100°C. There is a transition in matrix grain growth rate and mat…

Ferroelectric and Piezoelectric MaterialsAdvanced ceramic materials synthesisAcoustic Wave Resonator Technologies

High Resolution X-ray Structure of Galactose Mutarotase from Lactococcus lactis

James B. Thoden、Hazel M. Holden2002-06-01Journal of Biological Chemistry

Galactose mutarotase plays a key role in normal galactose metabolism by catalyzing the interconversion of beta-D-galactose and alpha-D-galactose. Here we describe the three-dimensional architecture of galactose mutarotase from Lactococcus lactis determined to 1.9-A resolution. Each subunit of the dimeric enzyme displa…

Enzyme Structure and FunctionEnzyme Production and CharacterizationAmino Acid Enzymes and Metabolism