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Enantioselective Heterogeneous Epoxidation and Hetero-Diels-Alder Reaction with Mn- and Cr-salen Complexes Immobilized on Silica Gel by Radical Grafting

Alexander Heckel、Dieter Seebàch2002-03-01Helvetica Chimica Acta

Vinyl-substituted chiral salens (salen=bis(salicylidene)ethylidenediamine) are used for attachment to Me3Si-hydrophobized silica gel (controlled-pore glass, CPG), carrying covalently bound mercaptopropyl ‘substituents', by AIBN-mediated radical addition of SH groups to styryl C=C bonds (Scheme 1, Table 1, and Figs. 1…

Mesoporous Materials and CatalysisPorphyrin and Phthalocyanine ChemistryPolyoxometalates: Synthesis and Applications

Correlation between photoluminescence properties and morphology of laser-ablated Si/SiOx nanostructured films

Andrei V. Kabashin、Jean‐Philippe Sylvestre、Sergiy Patskovsky 等 4 位作者2002-03-01Journal of Applied Physics

Pulsed laser ablation in an inert gas has been used to fabricate films containing silicon nanocrystals. We show that film microstructure is one of the main factors, determining long-term photoluminescence (PL) properties. Films with different porosity were found to exhibit PL signals with quite different peak energies…

Silicon Nanostructures and PhotoluminescenceNanowire Synthesis and ApplicationsIon-surface interactions and analysis

Total-energy-based prediction of a quasicrystal structure

M. Mihalkovič、Ibrahim Al-Lehyani、Eric Cockayne 等 8 位作者2002-03-01Physical review. B, Condensed matter

Quasicrystals are metal alloys whose noncrystallographic symmetries challenge traditional methods of structure determination. We employ quantum-based total-energy calculations to predict the structure of a decagonal quasicrystal from first-principles considerations. Our Monte Carlo simulations take as input the knowle…

Crystal Structures and PropertiesQuasicrystal Structures and PropertiesX-ray Diffraction in Crystallography

Infrared spectroscopic and theoretical studies on cobalt (II) complex of maleinitriledithiolate and 4, 4′-dimethyl-2, 2′-bipyridine

Zhenghe Peng、Cai Ping、Chen‐Jie Fang 等 4 位作者2002-03-01Wuhan University Journal of Natural Sciences

The complete experimental IR spectra and vibrational analysis of the title complex Co(mnt) (dmbpy) were reported in this paper. The results show that the complex molecule has a planar geometry belonging to point groupC 2v and ground electronic state with spin quartet. A new method for analyzing vibrational spectra of…

Magnetism in coordination complexesNonlinear Optical Materials ResearchOrganic and Molecular Conductors Research

Changes in properties of a 〈porous silicon〉/silicon system during gradual etching off of the porous silicon layer

E. F. Venger、T.Ya. Gorbach、S. I. Kirillova 等 5 位作者2002-03-01Semiconductors

Scanning electron microscopy has shown etching of a porous silicon layer in an HF solution to be irregular. The intensity of porous silicon photoluminescence significantly decreases during gradual etching off, and its peak initially shifts to shorter and then to longer wavelengths. Under red-light pulse excitation, ph…

Semiconductor materials and devicesSilicon Nanostructures and PhotoluminescenceNanowire Synthesis and Applications

Dispersion of barium gallogermanate glass

David E. Zelmon、Shyam Bayya、Jasbinder S. Sanghera 等 4 位作者2002-03-01Applied Optics

Gallogermanate glasses are the subject of intense study as a result of their unique combination of physical and optical properties, including transmission from 0.4 to beyond 5.0 microm. These glasses can be easily made into large optics with high-index homogeneity for numerous U.S. Department of Defense and commercial…

Glass properties and applicationsPhotorefractive and Nonlinear OpticsOptical and Acousto-Optic Technologies

Thermal degradation of two classes of block copolymers based on poly(lactic-glycolic acid) and poly(ε-caprolactone) or poly(ethylene glycol)

Fabio Bignotti、Maurizio Penco、Luciana Sartore 等 6 位作者2002-03-01Macromolecular Symposia

Thermodegradative investigations of two classes of multi-block copolymers containing poly(D,L-lactic-glycolic acid) (PLGA) and either poly(ethylene glycol) (PEG) or poly(ϵ-caprolactone) diol-terminated (PCDT) segments were performed. In particular, the influence of the type and length of the segments as well as of the…

Polymer crystallization and propertiesbiodegradable polymer synthesis and propertiesCarbon dioxide utilization in catalysis

Effect of Variations in Boiling Water Reactor Water Chemistry on Type 304 Stainless Steel Electrochemical Corrosion Potential

Y-J. Kim2002-03-01CORROSION

Effects of a variety of water chemistry conditions on the theoretical understanding and development of an electrochemical corrosion potential (ECP) prediction model to calculate the ECP of structural materials in boiling water reactors (BWR) are described. In particular, the effects of dissolved oxygen (O2), hydrogen…

Corrosion Behavior and InhibitionHigh-Temperature Coating BehaviorsHydrogen embrittlement and corrosion behaviors in metals

Nematic liquid‐crystal technology for Si wafer‐based reflective spatial light modulators

Minhua Lu2002-03-01Journal of the Society for Information Display

Abstract— Various nematic LC modes are reviewed and compared in terms optical throughput, driving voltage, response time, contrast ratio, and spectral responses for LCoS applications. The effects of fringe‐field‐induced disclination on display performance and the mechanism of slow response of the disclination line bet…

Liquid Crystal Research AdvancementsPhotonic Crystals and ApplicationsPhase-change materials and chalcogenides

Synthesis and structural characterization of luminescent materials. The elpasolite Cs 2 NaTbCl 6

Víctor Poblete、Gustavo Navarro、V. Martín 等 4 位作者2002-03-01Powder Diffraction

In this work we report the synthesis and structural characterization of the elpasolite Cs 2 NaTbCl 6 , belonging to the space group Fm3m. The synthesis is by solid state reaction, in controlled atmosphere. By means of thermal analysis (DTA/TGA), the best crystallization temperatures were obtained: 772.2 °C for 2 hours…

Luminescence Properties of Advanced MaterialsGlass properties and applicationsSolid-state spectroscopy and crystallography

The Quadruple System μ Orionis: Three-dimensional Orbit and Physical Parameters

Francis C. Fekel、C. D. Scarfe、David J. Barlow 等 6 位作者2002-03-01The Astronomical Journal

The star μ Orionis is a spectroscopic visual quadruple system in which each visual component is a short-period spectroscopic binary. The visual orbit has a period of 18.644 yr, a high eccentricity of 0.7426, and a high inclination of 96 2. The visual primary consists of an Am star and probably a G or early K dwarf tha…

Astro and Planetary ScienceHigh-pressure geophysics and materialsBoron and Carbon Nanomaterials Research

Behavior of transformer cores with multistep-lap joints

Albana Ilo2002-03-01IEEE Power Engineering Review

Recently, no-load losses P and noise n of transformer cores have been reduced by replacing the former single-step-lap (SSL) joints by multistep-lap (MSL) joints. On the other hand, the application of MSL in model cores was found not only to decrease P and n, but in some cases they increase. The aim of this paper is th…

Power Quality and HarmonicsMagnetic Properties and ApplicationsPower Transformer Diagnostics and Insulation

Influence of atmospheric pollutants on the natural and artificial aging of rigid poly(vinyl chloride)

Naïma Belhaneche‐Bensemra2002-03-01Journal of Vinyl and Additive Technology

Abstract The natural aging of rigid poly(vinyl chloride) (PVC) used in building and construction areas has been studied. Bars of PVC exposed in Algiers, where the concentrations of atmospheric pollutants (NO x , O 3 , hydrocarbons) are known, show a small drop in strain at break and stress at break, whereas hardness r…

Polymer Science and PVC

Single‐section plane assessment in grain boundary engineered brass

H. Davies、Valerie Randlè2002-03-01Journal of Microscopy

The present paper reports a comparative analysis of sigma 3 (in the coincidence site lattice notation) grain boundary types, in two grain boundary engineered brass specimens, by use of electron backscatter diffraction (EBSD) data coupled to the measurement of boundary traces in a single section. Although most of the d…

Microstructure and mechanical propertiesAluminum Alloy Microstructure PropertiesMetallurgy and Material Forming

Atomic structure of (Sr0.50Ba0.50)Nb2O6 single crystals in the series of (SrxBa1 − x)Nb2O6 compounds

T. S. Chernaya、T. R. Volk、И. А. Верин 等 5 位作者2002-03-01Crystallography Reports

Czochralski grown (Sr 0.50 Ba 0.50 )Nb 2 O 6 single crystals have been studied by the method of precision X-ray diffraction analysis. The structural characteristics of (Sr x Ba 1 − x )Nb 2 O 6 compounds with x = 0.33, 0.50, 0.61, and 0.75 were analyzed. The distributions of the Sr and Ba atoms over the crystallographi…

Ferroelectric and Piezoelectric MaterialsMicrowave Dielectric Ceramics SynthesisElectronic and Structural Properties of Oxides

X-ray powder diffraction study of ZnGa 2 Te 4

Rashmi Rashmi、U. Dhawan2002-03-01Powder Diffraction

ZnGa 2 Te 4 was found to crystallize in a defect tetrahedral structure with possible space group I 4 (82) with Z =2. Complete X-ray powder diffraction data were obtained and the unit cell parameters a and c and X-ray density were calculated. These were a =0.5930(1) nm, c =1.1859(3) nm, and D x =5.7×10 3 kg/m 3 .

Luminescence Properties of Advanced MaterialsCrystal Structures and PropertiesX-ray Diffraction in Crystallography

Simulation of Secondary Reformer in Industrial Ammonia Plant

Ying Yu2002-03-01Chemical Engineering & Technology

In order to develop a reactor design model for the secondary reformer in the industrial ammonia plant, the effectiveness factor and convection heat transfer coefficient between gas and catalyst surface have been studied. The temperature and composition of inlet gas to the catalyst bed are predicted using the kinetic e…

Catalytic Processes in Materials ScienceCatalysts for Methane ReformingAmmonia Synthesis and Nitrogen Reduction

Experimental procedure for crevice corrosion studies of Ni–Cr–Mo alloys in natural seawater

F.J. Martı́n、K. E. Lucas、E. A. Hogan2002-03-01Review of Scientific Instruments

An experimental procedure intended for crevice corrosion studies on Ni–Cr–Mo alloys is demonstrated. In this procedure a potentiostatic control of crevice corrosion specimens is applied to an immersible crevice cell design that uses a fluoroelastomer gasket crevice former. The procedure is demonstrated for a crevice s…

Corrosion Behavior and InhibitionHydrogen embrittlement and corrosion behaviors in metalsHigh Temperature Alloys and Creep

Pd/C-Catalyzed Release of Organonitrogen Compounds from Bituminous Coals

Xian‐Yong Wei、Zhong‐Hai Ni、Yu-Chun Xiong 等 8 位作者2002-03-01Energy & Fuels

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTPd/C-Catalyzed Release of Organonitrogen Compounds from Bituminous CoalsXian-Yong Wei, Zhong-Hai Ni, Yu-Chun Xiong, Zhi-Min Zong, Xiao-Hua Wang, Cheng-Wei Cai, Ya-Fei Ji, and Ke-Chang XieView Author Information School of Chemical Engineering, China University of Mining…

Electrocatalysts for Energy ConversionCatalytic Processes in Materials ScienceEnvironmental remediation with nanomaterials

An extended revision of the interlayer structures of one- and two- layer hydrates of Na- vermiculite

J. Beyer、Heinrich G. Reichenbach2002-03-01Clay Minerals

Abstract The interlayer structures in one- and two-layer hydrates of Na-vermiculite are described by presenting the positional parameters of their constituent atoms, including protons. The revision of these structures has been accomplished by: (1) determining accurate water contents of the two hydrates by thermoanalys…

Zeolite Catalysis and SynthesisClay minerals and soil interactionsIron oxide chemistry and applications