Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStereochemistry of asymmetric silicon. XV. Stereospecific hydrosilation and exchange reactions of R3SiH(D) catalyzed by Group VIII metal centersLeo H. Sommer, J. E. Lyons, and Hiroshi FujimotoCite this: J. Am. Chem. Soc. 1969, 91, 25, 7051–7061Publication Date (Print):Decemb…
Abstract This is the first paper of a series of reports concerning extended‐chain crystals of flexible, linear high polymers. The general conditions for crystal growth are discussed. Polymer crystallization is described as a two‐step process: nucleation of each crystallizing molecule to a folded‐chain conformation, fo…
Abstract The diffusion studies of several solvents in epoxy polymer reported by Kewi and Zupko in Part I of this series are explained with the solution obtained from the generalized diffusion equation which includes the internal stress contribution. The rate of permeation of a penetrant through a polymer film and the…
A nuclear magnetic resonance survey has been undertaken in order to gain a better insight into the nature of the complex species present in aqueous solutions of the rare-earth ions. Oxygen-17 and proton chemical shifts of water are reported and the effects of concentration and added anions upon them discussed. Nuclear…
1. Kinetic studies of glutamate dehydrogenase were made with wide concentration ranges of the coenzymes NAD(+) and NADP(+) and the substrates glutamate and norvaline. Initial-rate parameters were evaluated. 2. Deviations from Michaelis-Menten behaviour towards higher activity were observed with increasing concentratio…
Abstract Many materials which are stored and transported in bulk undergo exothermic decomposition or oxidation reactions at elevated temperatures. Such reactions may render them liable to spontaneous ignition if they are in sufficient quantity and at such a temperature that the rate of heat production exceeds the rate…
Abstract The thermal properties of a number of nitro‐substituted and analogous nonnitro‐substituted expoxide polymers were investigated. Dramatic increases in char yield and decreases in maximum rate of weight loss were observed for the nitro‐substituted systems compared to their nonnitrated analogs. These effects wer…
The aim of this paper is to show how van der Waals forces may account for profound changes in the IR spectra of alkylammonium saturated montmorillonite and the effect of adsorbed water molecules. IR spectra recorded on alkylammonium montmorillonite films submitted to vacuum and after exposure to water vapour show, in…
X-ray diffraction analyses of polycrystalline samples of Ca3TeO6 and Ca3WO6 have shown these compounds to be isostructural with Ca3UO6 (space group P21).
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCationic isomerization and oligomerization of isocyanideTakeo Saegusa, Naotake Takaishi, and Yoshihiko ItoCite this: J. Org. Chem. 1969, 34, 12, 4040–4046Publication Date (Print):December 1, 1969Publication History Published online1 May 2002Published inissue 1 December 1969h…
Summary Clinoptilolite-heulandite is reported from Jurassic, Cretaceous, and Palaeocene sediments in south-east England. It occurs mainly in 1–20 μm size fractions, and is associated with abundant montmorillonite and often also with glauconite and amorphous silica or low-temperature disordered cristobalite-tridymite.…
Soda‐alumina‐silica glass fibers were ion‐exchanged in potassium nitrate at 400°C; their strength was measured before and after exchange. The potassium concentration distribution and the optical retardation were also measured. The results for unetched fibers are consistent with the premise that the kinetics of exchang…
The motile species of diatoms in a largely non-motile association on grains of sand travel to the surface of the sand when buried, although they move more slowly and less often than species living in silt, and ascend each grain in turn. Diatoms on sand grains from a freshwater lake are found to migrate daily to and fr…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCrystal structure of tetraamminezinc octahydrooctaborate(-2), Zn(NH3)B8H8Lloyd J. GuggenbergerCite this: Inorg. Chem. 1969, 8, 12, 2771–2774Publication Date (Print):December 1, 1969Publication History Published online1 May 2002Published inissue 1 December 1969https://doi.org…
The different sources of nonlinearity in elastic structures undergoing large displacements are identified, and a general matrix formulation of the theory of nonlinear elastic structures is developed. It is shown that the nonlinearity results from the nonlinearity of the transformations relating member deformations to…
Abstract The acid dissolution of 8 chlorites in 2N Si-saturated HCl showed that there was no preferential dissolution of Al in octahedral positions and that the octahedral and tetrahedral sheets in the chlorite structure were equally attacked. An analysis of chemical data suggested a simple two-dimensional diffusion m…
Abstract Samples of smectites and vermiculites were evaluated to (1) determine the effects of source and amount of charge, (2) determine if a continuum of properties exists, and (3) improve the basis for differentiating criteria for identification. The montmorillonites expanded to the equivalent two-layer complex upon…
The unrestricted Hartree–Fock theory is used to investigate bond alternation in C4N+2H4N+2 cyclic polyenes. The possible ground states are examined as functions of the parameters in the Pariser–Parr–Pople model Hamiltonian. We show that charge-density-wave ground states do not exist for physical values of the input pa…
The sorption, permeation and diffusion of water in polydimethyl-siloxane (DMS), polydimethylmethylphenylsiloxane (PMS), and poly-3,3,3-trifluoropropylmethylsiloxane (FMS), and of methanol in FMS have been measured at a number of temperatures in the range 20°-50°C. For water, satisfactory agreement is obtained between…
Abstract Sr 2 PbO 4 , Ca 2 PbO 4x , Ca 2 SnO 4 und Cd 2 SnO 4 kristallisieren in orthorhombischen Gittern der wahrscheinlichen Raumgruppe Pbam—D . Wie Wie im Pb 3xO 4 liegen Ketten von PbO 6 ‐Oktaedern vor, die über gemeinsame Kanten verknüpft sind. Die zweiwertigen Atome sind von sieben Sauerstoffatomen in einer Anor…