Materials Literature
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The butyric acid forming bacteria, if continuously subcultured, undergo certain changes which affect morphological as well as physiological features. These changes were described as early as 1893 by Grimbert as degenerative changes of his cultures. Winogradsky (1902) found that his Clostridium pasteurianum ceased to f…
The thermal conductivities of polycrystalline alumina, beryllia and graphite have been measured between 2° K and room temperature The first two are dielectric solids but, even in the graphite specimens, the electronic contribution to the heat conduction is very small It is shown that the phonon mean free path is limit…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Experimental Determination of the Surface Tension of Magnesium OxideGeorge Jura and Carl W. GarlandCite this: J. Am. Chem. Soc. 1952, 74, 23, 6033–6034Publication Date (Print):December 1, 1952Publication History Published online1 May 2002Published inissue 1 December 1952…
The self-diffusion constant of the macromolecules in plasticized polystyrene and pure poly-n-butyl acrylate has been measured over a wide variety of conditions by a radioactive tracer technique. Well-characterized polymer fractions were used throughout. Simultaneous measurements of the bulk viscosity were also made. F…
Except for minor editorial revisions this paper is the reproduction of a report written for the Metallurgical Laboratory of the University of Chicago almost ten years ago, after the experimental production of a divergent chain reaction. This report has now been declassified and can be published. The present first part…
ABSTRACT The byssus threads, periostracum, hinge, ground substance of the shell, and the supporting material of the gills of Mytilus edulis, have been examined by physical, chemical, and histochemical means. The byssus threads, periostracum, and hinge have been shown to consist of a quinone-tanned protein. The byssus…
An attempt has been made to explain the observed viscous behavior of bulk polymers. It is found that the viscosity and diffusion may be represented by a theory which takes into account the coupling together of the molecules. Two equivalent treatments are given. One makes use of a segmental friction factor in the same…
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Experimental values for the solubility of carbon in nickel in the range 700°C to 1300°C yield the equation lnS=2.480−4,880/T, where S is the solubility in grams of carbon per 100 grams of nickel. Values obtained for the diffusion coefficient in the same range fit the equation lnD=0.909−20,200/T, where D is in cm2 per…
Abstract Polythene subjected to irradiation in the Harwell B.E.P.O. pile becomes cross-linked, and a new type of plastic is produced which does not melt at about 115° C, nor dissolve in hot organic compounds. The mechanical properties are also altered, especially above 115° C, when the plastic shows rubber-like elasti…
Vitamin A and retinene, the carotenoid precursors of rhodopsin, occur in a variety of molecular shapes, cis-trans isomers of one another. For the synthesis of rhodopsin a specific cis isomer of vitamin A is needed. Ordinary crystalline vitamin A, as also the commercial synthetic product, both primarily all-trans, are…
The magnetic spectrum of a sintered ferrite, previously studied by the authors at room temperature and found to contain an rf resonance, attributed to domain wall displacements, and a microwave resonance, attributed to domain rotations, has now been observed at 77\ifmmode^\circ\else\textdegree\fi{}K, 195\ifmmode^\circ…
A qualitative analysis of Gallagher's measurements of plastic flow in germanium and silicon is made. It is reasonable to suppose the slip occurs by motion in {111} planes of dislocations having a Burger's vector equal to an allowed translation in the ($1\overline{1}0$) direction. It is suggested, following current tho…
Abstract A comparison is given between flow in liquids, creep in crystals and intercrystalline slip. A further comparison is made between latent heats of fusion, shear moduli and the energies to form vacancies.