Materials Literature
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The quantum theory of the frequency- and wave-number-dependent dielectric constant in solids is extended in order to study the full dielectric constant tensor and to include local-field effects. Within the framework of the band theory, an explicit expression for the dielectric constant tensor, neglecting local-field e…
Abstract After a brief introduction discussing the basis of molecular-field theories, we introduce a generalization of Anderson’s treatment of antiferromagnetism which enables us to take higher-order exchange interactions into account as well as anisotropy terms. We restrict ourselves to terms quadratic in the spins.…
Abstract X-ray analyses of selected samples from the argillaceous subdivisions of the English Wealden indicate that illite, kaolinite, and mixed-layer structures are present in variable amounts. The clay mineral assemblage is thought to reflect parent material, weathering conditions in the source area, and possibly so…
Browsing in books, review articles and conference reports, one sometimes nowadays comes across pictures like fig. 1. This peculiar object, which might be mistaken for a piece of modern sculpture, is labelled “The Fermi surface of magnesium”. What does it mean, to say that magnesium has a Fermi surface, and how is it d…
Abstract The principle of the new gas‐phase method of polycondensation consists of carrying out the polycondensation reaction of two high reactive compounds at a liquid—gas interface. The gas‐phase method permits the synthesis of polyamides with rapidly hydrolyzing diacid chlorides (e.g., oxalyl chloride), which canno…
Abstract The swelling of cellulose in alkali solutions has been the subject of numerous investigations in the past. However, there still exists a controversy as to whether the reaction with alkali yields a true alcoholate or an addition compound without ionization of the cellulose. This study presents experimental dat…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNitric Acid Dissolution of Uranium-Molybdenum Alloy Reactor FuelsW. W. Schulz, R. E. Burns, and E. M. DukeCite this: Ind. Eng. Chem. Process Des. Dev. 1962, 1, 2, 156–160Publication Date (Print):April 1, 1962Publication History Published online1 May 2002Published inissue 1 April…
Abstract The molecular weight of silk fibroin in several different solvent systems has been measured by light‐scattering techniques. The values obtained lie between 250,000 and 450,000, with a tendency to lie fairly close to 300,000. The difference between this value of the molecular weight and the values obtained by…
Polycrystalline samples of five iron-aluminium solid solutions were subjected to various heat treatments either (i) in a strong magnetic field, or (ii) under tensile stress. For treatment (i) the samples were in the form of cylinders, while in case (ii) they were machined into this form after stress treatment. Torquea…
Determination and refinement of the crystal structures of väyrynenite and euclase show that these minerals have related, but not identical, structures. Väyrynenite contains chains of BeO 2 (OH) 2 and PO 4 tetrahedra linked by Mn-O and hydrogen bonds; euclase contains chains of BeO 3 (OH) and SiO 4 tetrahedra linked by…
The total groove volume is estimated for a short (similar 1 mm) abrasion stroke of silver on dry grade-3 emery paper (mean particle diameter 150 μm) at approximately 1 kg load. This is compared with the mass wear rate, thus giving an estimate of the order of 10% for the proportion of the total groove volume removed as…
Abstract The degrees of crosslinking of three post‐gelation high‐conversion copolymers were measured by γ‐irradiation, extraction, and swelling experiments. The copolymers containing 0.2, 0.5, and 1.0 mole‐% of the crosslinker were prepared by suspension polymerization at 60°C. with a free‐radical catalyst. The degree…
By C. W. Richards London: Chapman and Hall Ltd. Pp. xiv + 546. Price 60s. Assessment of this book is rendered difficult by the lack of any indication of the kind of reader for whom it is intended, and by a rather misleading title. Although some of the topics dealt with in a qualitative manner are quite advanced, the s…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDirect Determination of Metalloporphyrins in Boscan Crude Oil.J. M. Sugihara and R. M. BeanCite this: J. Chem. Eng. Data 1962, 7, 2, 269–271Publication Date (Print):April 1, 1962Publication History Published online1 May 2002Published inissue 1 April 1962https://pubs.acs.org/…
An electron microscope study has been made of metastable β-brass containing 61.0% copper, 39.0% zinc. It was observed that during electrolytic polishing of 0.005 in. thick foil the very thin regions of β at the edges of the foil transformed spontaneously to a face-centred cubic structure α”. This transformation is sim…
Abstract In order to verify precisely the applicability and reasonableness of the time–humidity superposition method to hydrophilic crystalline polymers, stress relaxation measurements were carried out with films of polyvinyl alcohol and nylon 6 by means of a table model Instron Tensile Tester equipped with a special…
Abstract The thermolytic decomposition of crystalline and amorphous poly( tert ‐butyl acrylate) was investigated. At elevated temperatures thin films of polymer were found to evolve isobutylene quantitatively. The weight loss curve has been analyzed, and a mechanism has been suggested involving a slow random decomposi…
The theoretical models of Callaway and Klemens are compared to experimental results in (a) silicon and diamond, (b) solidified argon and neon, and (c) KCl and NaF, which are taken from the literature. Three sources of scattering are postulated: phonon-phonon processes, isotopic point defect scattering, and boundary sc…
The absorption and fluorescence spectra of 1% and 10% Pr3+ in LaBr3 were observed and an analysis carried out. The energy levels of these Pr3+ ions are very similar to Pr3+ in LaCl3, except that the centers of the J levels differ on the order of 102 cm−1. This corresponds to a change in Slater integrals of 0.5%. This…
Excluded volume theory of nonionic high-polymer solutions has been extended to mixed polyelectrolyte-added simple electrolyte systems. A systematic study has been undertaken of fractionated polyvinylsulfonate alkali halide systems. ``Ideal'' Θ temperatures, determined from phase separation experiments and from the van…