Materials Literature
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Properties of α-alumina surface, dissociated fraction of polyacrylic acid, and the interaction between alumina surface and polyacrylic acid were investigated in aqueous suspensions in the pH range of 2.2 to 10.5. The isoelectric point of the colloidal α-alumina particles was pH 7.7, and the surface was charged positiv…
For pt.IX see ibid., vol.7, no.6, p.5 et seq. (1991). An overview of engineering practice related to partial discharge (PD) measurements in gas-insulated substations (GISs) is provided. The following questions are addressed: why measure PD in GIS?; in which phases of the life cycle should PD be measured?; what PD meas…
The use of an imaging plate as a two-dimensional (2-D) detector removes many of the difficulties that arise in performing angle-dispersive powder diffraction at high pressures in a diamond-anvil cell. Due to the 2-D nature of the imaging plate, a substantial part of each Debye Scherrer ring is intercepted and recorded…
The introduction of a metal into a mesogenic molecule can result in a complex with interesting electrical and magnetic properties. By reacting the non‐mesogenic cyclic amine shown in the figure with Ni(NO 3 ) 2 · 6H 2 O in absolute THF the first member of a new class of columnar liquid‐crystalline metal complexes with…
The effect of γ\ ightleftarrowsε cyclic transformation on the subsequent γ→ε martensitic transformation has been studied in an Fe-24%Mn-6%Si shape memory alloy in order to obtain fundamental information on the role of Si in the shape memory effect. The γ→ε martensitic transformation is markedly enhanced by the thermal…
We consider three systems containing rigid and/or flexible main-chain nematogenic polymers: mixtures of a rigid and a flexible polymer, mixtures of two different rigid polymers, and a system of diblocks of rigid and flexible pieces. The flexible components are modeled as chains with freely rotating bonds, while the ri…
We have prepared novel colloidal polyaniline–silica composites by chemically polymerising aniline in the presence of small silica particles of 38 ± 7 nm diameter; these composites have been characterised by various techniques including thermogravimetry micoanalyses, scaning, electron microscopy, photon correlation spe…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMiscibility and phase separation in poly(methyl methacrylate)/poly(vinyl chloride) blends: study of thermodynamics by thermal analysisSunny Shen and John M. TorkelsonCite this: Macromolecules 1992, 25, 2, 721–728Publication Date (Print):January 1, 1992Publication History Pub…
The scanning electrochemical microscope has been used to probe the diffusion layer by measuring the potential difference between a large reference electrode located in the bulk of the solution and a microindicator electrode positioned a few µm away from a substrate electrode. Ag microdiscs (10 and 50 µm diameter) have…
The infrared spectra of CO adsorbed at 77 K on sintered polycrystalline MgO and Ni/MgO, Co/MgO solid solutions, containing 10% nickel and cobalt in atoms are reported. These solids are properly designed for the estimation of the role played by d–π overlap in the bonding between the isolated transition-metal cations an…
Trialkylstannyltetrathiafulvalenes undergo palladium-catalysed cross-and homo-coupling reactions to give aryl-substituted tetrathiafulvalenes and bitetrathiafulvalene; the methodology has been applied to the synthesis of p-phenylenebistetrathiafulvalene and 2,5-thiophenediylbistetrathiafulvalene
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThin-film processing and optical properties of conjugated rigid-rod polyquinolines for nonlinear optical applicationsAshwini K. Agrawal and Samson A. JenekheCite this: Chem. Mater. 1992, 4, 1, 95–104Publication Date (Print):January 1, 1992Publication History Published online…
The complete amino acid sequence of glutamate dehydrogenase from the thermoacidophilic archaebacterium Sulfolobus solfataricus has been determined. The sequence was reconstructed by automated sequence analysis of peptides obtained after cleavage by trypsin, cyanogen bromide, Staphylococcus aureus V8 protease and pepsi…
A novel approach for designing optimal multilayer filters based on a real-coded genetic algorithm is presented. Given the total number of layers in the filter, as well as the electrical properties of the materials constituting each layer, the algorithm iteratively constructs multilayers whose frequency response closel…
The generation of quantised-state (Q-state) particles of CdS, CdSe, CdTe, CdSxSe1–x, CdSxTe1–x and CdSexTe1–x in polymerized nonacosa-10, 12-diynoic acid Langmuir–Blodgett (LB) films is described. The use of mixed surfactants and mixed counterions Cd2+ and Ca2+ in the LB films is shown to influence the size of the par…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNanoscale platinum(0) clusters in glassy carbon: synthesis, characterization, and uncommon catalytic activityNicolas L. Pocard, Daniel C. Alsmeyer, Richard L. McCreery, Thomas X. Neenan, and Matthew R. CallstromCite this: J. Am. Chem. Soc. 1992, 114, 2, 769–771Publication Da…
Pt black catalysts have been characterized by X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). The spectra measured after standard purification (O2 and H2 at 600 K) compared well with those of a purified reference Pt foil. All samples exhibited pronounced Fermi-edge intensities…
The anomalous initial reduction peak in cyclic voltammograms of polypyrole in acetonitrile has been shown, by impedance spectroscopy and X-ray emission analysis, to be due to the uptake of cations. Reoxidation is accompanied by anion uptake. As a result of these two processes, polypyrrole that has been electrochemical…
A method is presented, which allows, with a minimum of assumptions, the determination of the molar absorption coefficients of the coloured form of photochromic compounds and their forward and reverse quantum efficiencies. The approach used combines a modified Fischer's method with an improved intensity variation techn…
Two [2]rotaxanes, composed of (i) a polyether chain intercepted by (a) one centrally-located and (b) two symmetrically-located π-electron-rich hydroquinol rings and terminated by free-base and metallated (Zn) tetraaryl-porphyrin groups respectively and (ii) a tetracationic cyclophane constructed of two π-electron-defi…