Materials Literature
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Se presenta un nuevo procedimiento para contrarrestar la acción nociva de las temperaturas bajas sobre los morteros y hormigones. Se Detallan su fundamento, ventajas e inconvenientes. El procedimiento es económico.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Temperature Dependence of Relaxation Mechanisms in Amorphous Polymers and Other Glass-forming LiquidsMalcolm L. Williams, Robert F. Landel, and John D. FerryCite this: J. Am. Chem. Soc. 1955, 77, 14, 3701–3707Publication Date (Print):July 1, 1955Publication History Publi…
Abstract Neutron-diffraction measurements demonstrate that the hydrogen atoms in the ferroelectric form of potassium dihydrogen phosphate are in ordered positions, in accordance with Slater’s theory and the polar orthorhombic structure. The maintenance of a crystal as a single ferroelectric domain by application of an…
thickness. The last equation is equivalent to the con- dition that the stress component cr"vanishes. Eliminat- ing all variables except ws in (5), we find d'we
The theoretical basis for exciting luminescence by the application of an electric potential to a crystalline dielectric or semiconductor is considered. Three mechanisms of excitation are each shown to be theoretically feasible in appropriate solids and with suitable local field conditions: (1) the ionization of impuri…
The orthogonalized plane wave (OPW) method is used to compute estimates of the energy eigenvalues associated with states for which k=0 in the valence and conduction bands of a perfect silicon crystal; these estimates are given in Table I. A simple method for determining an approximate crystal potential is described. T…
Abstract When subjected to high-energy radiation, polydimethyl siloxanes can be cross-linked to form insoluble amorphous structures which are transparent and have marked rubber-liko properties. Data are given on the relation between molecular weight and bulk viscosity, which is often used to characterize these polymer…
Abstract The electronic structure of a regular icosahedron of boron atoms is investigated theoretically by the method of molecular orbitals. It is found that thirteen bonding orbitals are available for holding the icosahedron together, besides the twelve outward-pointing equivalent orbitals of the separate atoms. The…
A Hopkinson bar wire strain gauge technique has been developed for the measurement of projectile penetration force as a function of time. The elastic strain wave resulting from projectile impact and penetration of the bar end is measured with oscillographic equipment; this strain pattern is a direct and continuous mea…
Abstract Experiments are described in which the effect of the presence of foreign substances on the rate of crystallization of natural rubber at −26° C is examined. It is shown that small amounts of suitable impurities, some of which are present in smoked sheet and other plantation rubbers, accelerate the crystallizat…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHeat Capacities at Low Temperatures and Entropies at 298.16°K. of Aluminates and Ferrites of Lithium and SodiumE. G. KingCite this: J. Am. Chem. Soc. 1955, 77, 12, 3189–3190Publication Date (Print):June 1, 1955Publication History Published online1 May 2002Published inissue 1…
Abstract Data are presented on the fracture of inoculated-iron thin-wall tubes, investigated under various ratios of axial to tangential stress, ranging from pure tension to pure compression. These data are consistent with published data on gray cast iron. It may be assumed that in cast-iron, plates of friable graphit…
In this paper the formation of a gelatinous hydrate phase from the natural dicalcium silicate minerals larnite and bredigite is described. Detailed study of the gel so formed indicates that the process of hydration is a solid reaction which is effeeted by diffusion. The preferred orientation of the hydrate phase sugge…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNON-SOLVATED ALUMINUM HYDRIDE1George Chizinsky, Gordon G. Evans, Thomas R. P. Gibb Jr., and M. John Rice Jr.Cite this: J. Am. Chem. Soc. 1955, 77, 11, 3164–3165Publication Date (Print):June 1, 1955Publication History Published online1 May 2002Published inissue 1 June 1955htt…
The preparation of CaZrO 3 by solid‐state reactions at 1450° to 2000°C. is described. A very stable material was formed by the reaction of CaCO 3 and ZrO 2 , in equimolar proportions, at a final temperature of 1850°C. Lattice constant values for this material agreed with data reported by previous investigators. The li…
The chemical composition of a number of silk fibres of different origins, and of the Byssus fibre of Pinna nobilis, has been determined by chromatographic analysis. The proportion in the silks of amino acids with long side-chains to those with short side-chains, enables them to be placed into three main groups. These…
Abstract Additional polyvinylpyrrolidone samples of great homogeneity have been prepared, and their intrinsic viscosity and molecular weight (by light scattering) have been determined in water and chloroform. In view of the new results the previous data were reinterpreted particularly with respect to the shift in K (i…
Abstract Es wird die Phasenkontinuität und die Stabilisierung von Öl‐in‐Wasser‐ bzw. von Wasser‐in‐Öl‐Emulsionen durch Stoffe, die mehr in der öligen oder mehr in der wäßrigen Phase löslich sind, oder durch feste, unlösliche Stoffe, die entweder von der öligen oder von der wäßrigen Phase benetzt werden, besprochen. Un…
The Raman spectrum of furfural has been obtained photoelectrically in the liquid over a temperature range of 50° and in solution. The infrared spectrum has been obtained for the solid, the liquid (over a temperature range of 90°), and in dilute solution over a 50° temperature range. The vibrational spectrum is interpr…
1. The carbonic anhydrase inhibitors 2-benzothiazolesulfonamide (Cpd. I) and 2-acetylamino-1,3,4-thiadiazole-5-sulfonamide (Diamox) (Cpd. II) markedly reduced the rate of deposition of calcium in the shell of the oyster Crassostrea virginica. Treatment of oysters with Cpd. I, 1:80,000, for 7-8 hours reduced the rate t…