EXAFS Study of the Passive Film on Iron
Abstract not Available.
Materials Literature
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Simple theoretical estimate of surface energy, bulk modulus, and atomization energy of AIBIIIC compounds
Abstract The specific surface energy of the (112) face of the chalcopyrite structure A I B III C 2 VI compounds is calculated accounting for contributions from long‐ranged, metallic forces and short‐ranged, directional covalent forces. From the surface energies the bulk modulus and the atomization energy of all A I B…
Spatially varying polarization in ice
We calculate the response of an ice crystal to a spatially varying applied electric field. The dielectric polarization of the ice is not assumed to be proportional to the local macroscopic electric field. Instead, we formulate an expression for the free-energy density of an ice crystal with non-uniform polarization an…
Genetic Divergence Within the Genus Liriodendron (Magnoliaceae)
Clifford R. Parks, Norton G. Miller, Jonathan F. Wendel, Karen M. McDougal, Genetic Divergence Within the Genus Liriodendron (Magnoliaceae), Annals of the Missouri Botanical Garden, Vol. 70, No. 4 (1983), pp. 658-666
A Novel Trivalent Chromium Electroplating Bath
SummaryA novel process for the plating of decorative chromium from the trivalent state is described. Features of this new process include: colour of deposit virtually indistinguishable from that of conventional chromium; excellent throwing and covering power; low chromium concentration (ca 5 g/1) and simple effluent t…
Photoreduction of benzo-1,4-quinone sensitised by metalloporphyrins
Benzo-1,4-quinone quenches the triplet excited state of many metalloporphyrins in ethanol solution and the overall quenching rate constants are a simple function of the thermodynamic driving force for electron transfer. The resultant ion-pair can dissociate to separated ions or recombine to ground-state reactants. The…
Retrogradation of Some Starch Mixtures
Abstract Retrogradation tendencies of starch from local materials at two storage temperatures (10 and 30°C) were investigated. The kinetics of the crystallization process were studied using the Avrami equation. The values for the Avrami exponent and rate constant differ greatly at the two storage temperatures and for…
Elastic photon scattering at small momentum transfer and validity of form-factor theories
Various form-factor theories used to predict Rayleigh-scattering cross sections of gamma-ray photons are examined. For energies above the $K$ threshold comparisons are made with more accurate numerical calculations, for a high-$Z$ element (Pb), primarily at small momentum transfers [up to $x\ensuremath{\equiv}{\ensure…
Molecular structure of an aminosilane coupling agent as influenced by carbon dioxide in air, pH, and drying conditions
The molecular structures of the hydrolyzates of γ-aminopropyl-triethoxysilane (γ-APS) were studied by Fourier transform infrared spectroscopy (FT-IR). The molecular structure of γ-APS is a function of the pH of the solution and the drying conditions. In the partially cured film, cast from a 20% by weight γ-APS aqueous…
Radiation-induced photoconductivity in polymers: Poly(vinylidene fluoride) compared with polyethylene terephthalate
Transient and dc photoconductivity measurements are presented for two low-mobility dielectrics, poly (vinylidene fluoride) and polyethylene terephthalate. In each case, the data are analyzed using the present models for dispersive transport, and the inadequacies of these theories when applied to these low-mobility die…
Mechanism of the silver-catalysed heterogeneous epoxidation of ethylene
Chemisorbed atomic oxygen is the crucial surface species which selectively oxidises ethylene to ethylene oxide; adsorbed dioxygen plays no direct role in this reaction.
Statistical description of multimodal atomic probability densities
A general method for describing multimodal atomic densities is presented. It is based on series expansions of a harmonic Gaussian probability density function. The most suitable expansion is of the Gram-Charlier type; its Fourier transform can be easily inserted in a structure factor equation. This statistical method…
A melt mechanism for the thermal decomposition of ammonium dichromate
Microscopic examination of (NH4)2Cr2O7 crystallites, previously decomposed to measured extents, has given strong evidence that reaction proceeds through the intervention of a melt. This reaction has previously been accepted as occurring in the solid phase and the use of higher magnifications than were applied previous…
Structure and Dynamics of Liquid Crystalline Polymers from Deuteron NMR
Abstract The molecular structures of thermotropic liquid crystalline polymers, which have been synthesized systematically in recent years, are described according to the model of decoupling the molecular motions of the mesogenic groups and the polymer chain by inserting a flexible spacer. The molecular structure is re…
Polymer stabilization by hindered amines
Abstract
Kinetics of metalloporphyrin formation with particular reference to the metal ion assisted mechanism
Article Kinetics of metalloporphyrin formation with particular reference to the metal ion assisted mechanism was published on January 1, 1983 in the journal Pure and Applied Chemistry (volume 55, issue 1).
Heat Capacity and Other Thermodynamic Properties of Linear Macromolecules. IX. Final Group of Aromatic and Inorganic Polymers
In this final review, a series of polymers which include aromatic rings and/or inorganic chain atoms are treated. Heat capacities of poly(4,4′-isopropylidenediphenylene carbonate), polyphenylenediamides, polyheteroarylenes, poly(dimethyl siloxane), poly(diethyl siloxane), poly(trimethylsilyl ethylene), poly(dimethylph…
Effect of grinding on the degree of crystallinity of cephalexin powder.
The effect of grinding on the degree of crystallinity of cephalexin (CEX) powder was investigated. The intensities of the X-ray diffraction peaks of crystalline CEX decreased with increasing grinding time in an agate shaker mill, and after 4 h showed the same halo pattern as the noncrystalline solid (NC) obtained by t…
A Landau-de Gennes theory of nematic polymers
For a semi-flexible, nematic polymer, the Landau-de Gennes expansion for the free energy of the homogeneous melt is derived. The theory contains three parameters : the degree of polymerization, the inherent elasticity of the polymer chain, and the quadrupolar mean field between monomers. The dependence on chain length…
Thin colloidal crystals : a series of structural transitions
We study thin layers of colloidal crystals made of polystyrene balls (1.1 μm diameter) in aqueous suspension. These thin layers are produced by confining colloidal crystals between two glass planes, which act as repulsive and perfectly smooth boundaries at colloidal scales. When the two planes form a wedge, a continuo…