Materials Literature
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Bone mineral and synthetic calcium-deficient carbonate apatite (CDCA), when defined in terms of their respective thermal stabilities and ignition products, are homologous. When heated to 550 degrees, they may have a structure similar to that of the mineral dahllite. When heated to temperatures greater than 550 degrees…
Micromechanisms of transgranular cleavage fracture in ferritic steels have been investigated, particular attention being paid to the dependence of cleavage fracture stress σf on grain size over the range from 3·5 to 34·3 μm. It is found that σf increases less than linearly with d−1/2, where d is the grain diameter, wh…
Kinetics of the anionic polymerization of ε-caprolactone (εCL) initiated with (CH3)3SiO−K+ and carried out in THF solution has been studied in the temperature range from 0 to 20°C by using a calorimetric method. From the kinetic results and from conductometric measurements of the dissociation constant of the living Po…
We recently reported the discovery of stable disclinations of strength ± 3/2 and ± 2 in mixtures of several nematogenic compounds with a non-mesomorphic compound having plate-like molecules. We describe here further detailed observations on these defects, particularly on pairs of high strength disclinations.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTImidazole complexes of low-spin iron(III) porphyrin .pi.-cation radical species. Models for the compound I .pi.-cation radical state of peroxidasesHarold M. Goff and Martin A. PhillippiCite this: J. Am. Chem. Soc. 1983, 105, 26, 7567–7571Publication Date (Print):December 1,…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSpectroscopic properties, electronic levels, and crystal field parameters of pentakis(nitrato)europate(III) ionsJ. C. G. Buenzli, B. Klein, G. O. Pradervand, and P. PorcherCite this: Inorg. Chem. 1983, 22, 25, 3763–3768Publication Date (Print):December 1, 1983Publication His…
Correlation of octahedral ion electronegativity with band frequency appears to best account for observed OH stretch frequencies in the di- and trioctahedral minerals potassic mica, talc and saponite. The site of charge substitution in the octahedral layer or in the tetrahedral layer affects the band frequencies also.…
Abstract Spherical kaolinite has been synthesized for the first time from noncrystalline aluminosilicate material in hydrothermal experiments conducted between 150° and 250°C and under autogenous vapor pressure. Spherules, whose mean diameters depended on growth conditions (0.1–0.6 μ m), were formed surrounding the no…
Laser excited fluorescence and infrared absorption spectra of single crystals of praseodymium diluted with anhydrous lanthanum trichloride was examined. A number of new fluorescing levels have been observed, numerous additional crystal field components identified, and a more complete energy level scheme is presented.
Abstract Difficulty in controlling and determining the structural parameters of polymer networks has hindered experimental studies on the glass transition in crosslinked polymers. A series of wellcharacterized networks of poly(propylene glycol) having narrow network chain‐length distributions and average molecular wei…
Abstract The mechanism of action of ammonium polyphosphate (APP) and polyurea (PU) as flame retardant (FR) agents for polypropylene (PP) was examined. The APP–PU system behaves as an intumescent flame‐retardant (IFR) formulation. Comparison of the oxygen index (OI) measured on molded pellets and rods, values of the po…
Molecular dynamics calculations based on atom–atom potentials and rigid nonpolarizable ions are used to study the cubic rotator phases of ammonium bromide (NH4Br). The nature of the orientational order exhibited by the ammonium ions is characterized using tetrahedral rotor functions (Mμ, μ=1,7). The quantities 〈M2μ〉 a…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCarbon-carbon bond forming and breaking by a metal-assisted redox process in a nickel(II)-Schiff base complexSandro Gambarotta, Fabio Urso, Carlo Floriani, Angiola Chiesi-Villa, and Carlo GuastiniCite this: Inorg. Chem. 1983, 22, 26, 3966–3972Publication Date (Print):Decembe…
Abstract Kohlenstoff‐„Modifikationen”︁ zeigen — sofern sie überwiegend die Schichtstruktur des Graphits aufweisen – 1) elektronische Leitfähigkeit, 2) die Fähigkeit, Ionen oder Moleküle zwischen die Schichten des Gitters einzulagern, und 3) die Fähigkeit, über funktionelle Gruppen ihrer Oberflächen (im wesentlichen de…
Interdiffusion in Cu–Al thin film bilayers at temperatures between 160 and 300 °C has been studied by a combination of glancing-incidence x-ray diffraction, Rutherford backscattering spectroscopy, and transmission electron diffraction and microscopy. A sequential intermetallic compound formation was observed in sample…
Monoclinic telluric acid ammonium phosphate (TAAP) is shown to be a new class m ferroelectric with a Curie temperature close to ambient (48°C). Emphasis is placed on dielectric and thermal properties, but some optical results are also reported. The material behaves closely like TGS and, from a practical point of view,…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTClay-supported reagents. 5. Nitration of estrone into 2-nitroestrone by clay-supported ferric nitrateAndre Cornelis, Pierre Laszlo, and Pascal PennetreauCite this: J. Org. Chem. 1983, 48, 24, 4771–4772Publication Date (Print):December 1, 1983Publication History Published onl…
Abstract A preliminary set of ‘rules’ for acid-catalysis by ion-exchanged montmorillonites has been derived from the reaction of alkenes, alcohols and alicyclic acids over such catalysts. It has been shown that: 1. Cr(III) and Fe(III) are the most active interlayer cations. Although Al is also active, the exact proced…
Abstract Compositions and elemental distributions of anodic films formed on aluminium in aqueous borate electrolytes have been investigated by Rutherford backscattering spectroscopy (RBS) and associated nuclear reaction methods, together with controlled crystallization of film sections in the transmission electron mic…
Experimental studies were performed in a 4.8×2.8×3.5 m3 cold room with a HV transformer of 124 kVA, 120 kV. Atmospheric ice was accreted on a vertical string of three types of insulators: a classic glass insulator and two long-rod synthetic insulators. The results obtained show that flashover occurs at the lowest volt…