Materials Literature
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The molecular field treatment of the magnetic properties of ferrites given by N\'eel is extended to take into account the antiferromagnetic exchange interactions within the two magnetic sublattices. On further subdividing the two lattices, we show that the ground state may, (1) have an antiparallel arrangement of the…
Abstract Porphyrins have been shown to be stronger bases than previously supposed, two protons being added in two stages to the nitrogen atoms in the conjugated tetrapyrrolic ring as the pH of an aqueous solution is decreased from pH 12 to 0. The existence of mono-cations of certain porphyrins in aqueous solution with…
Abstract The results are given of some measurements of the absorption coefficient and refractive index of water, methyl and ethyl alcohols at wave-lengths of 6·2 mm, 1·24 cm and 3·21 cm over the temperature range —10 to 50°C, including some observations on water in the supercooled state. The method used is based upon…
X-ray measurements have been made on a number of colchicine derivatives, in a search for a crygtal suitable for a structure analysis of the colchicine molecule. The methylene bromide and iodide addition complexes, C~eH25NO6.CH~X~, are isomorphous, in space-group P212~2 ~, with 4 molecules in a cell of dimensions a=9.1…
At compositions near FesN and Fern the structures proposed for e iron nitrides by previous workers from incomplete X-ray data are confirmed. At intermediate nitrogen concentrations and at concentrations less than that of FesN, additional superlattice reflexions, unaccounted for by these previously proposed structures,…
Einführung, Schrifttum und Ziel der Arbeit. Versuchsausführung: Versuchswerkstoffe, Stabform, Dauerversuche; Vorbeanspruchung: Verformungsgeschwindigkeit, Reckgrad und Verformungs-Zeit-Kurven; metallographische Untersuchungen. Ergebnisse der statischen und dynamischen Zugversuche: Vergleich der Werte von Streckgrenze,…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Heat Capacity and Magnetic Properties of Single Crystal Copper Sulfate Pentahydrate from 0.25 to 4°K.1T. H. Geballe and W. F. GiauqueCite this: J. Am. Chem. Soc. 1952, 74, 14, 3513–3519Publication Date (Print):July 1, 1952Publication History Published online1 May 2002Pub…
Experiments on the interdiffusion of copper-alpha-brass and copper-nickel couples and sandwiches have shown that there is an increase of volume in the diffusion zone as a result of diffusion This increase in volume is associated with the formation, in the diffusion zone, of voids with crystallographic faces These void…
Gerald W. Prescott, Arthur M. Scott, The Algal Flora of Southeastern United States. V. Additions to Our Knowledge of the Desmid Genus Micrasterias 2, Transactions of the American Microscopical Society, Vol. 71, No. 3 (Jul., 1952), pp. 229-252
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermal Decomposition of Sulfur Compounds. II. 1-PentanethiolC. J. Thompson, R. A. Meyer, and J. S. BallCite this: J. Am. Chem. Soc. 1952, 74, 13, 3287–3289Publication Date (Print):July 1, 1952Publication History Published online1 May 2002Published inissue 1 July 1952https:/…
Conclusions important to the practice of electron microscopy are drawn from experiments. Particles of Dow Latex 580G are unstable under electron beams and best micrographed at low intensity. Two different effects of radiation are noted. At low intensity the mean diameter in the present work was 2890A, the standard dev…
A morphological study of natural populations of Tabellaria in fresh water suggested that there were two fundamentally different types of growth (and therefore frustule structure) in the genus, and this has been confirmed by means of unialgal clone cultures. The existence of these different types of growth forms the ba…
In the course of investigation of the rectifying properties of silicon very interesting photoelectric properties were found. The first photo-cells were cut from hulk silicon in which a natural potential barrier was found. A typical spectral characteristic of such a cell is shown. This early work was followed by the di…
The Onsager and Kirkwood theories of polar liquids have been used to analyze the available experimental data on the pressure dependence of the dielectric constant. It is found necessary in most cases to assume an appreciable decrease in the dipole moment arising from intramolecular distortion which may be large enough…
It is shown on theoretical grounds that the electronegativity of oxygen in silicates depends upon the Si-0 structure as well as upon the Al/Si ratio in the (Si/Al)O₄ tetrahedra. The more Si-O-Si links in a silicate structure, the larger the electronegativity of the oxygen atoms attached to metallic ions. That is, the…
By assuming that the activation energy for flow in associated liquids is proportional to the inverse square of the absolute temperature, an empirical expression for the viscosity is obtained, which fits the data well. An empirical expression for the activation energy of mixtures of associated liquids is also proposed.
Abstract The theory of molecular distribution in condensation polymers has been extended to include systems of a rather general type. Equations for the distribution and the weight‐average molecular weight are given.
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