Materials Literature
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Complex Young's modulus, rigidity and bulk modulus are measured at 33 kc/s, 66 kc/s and 1 Mc/s for polystyrene, polymethyl methacrylate, polyvinyl acetate and phenol resin. In each material, the storage modulus-temperature curve has a discontinuity in the slope, irrespective of frequency and type of modulus, at the gl…
Theoretical analyses are given of the effects of fiber properties and yarn structure on singles yarn bending rigidity, assuming the fibers to be elastically isotropic and to exhibit linear stress—strain behavior. The two extreme cases of complete freedom and no freedom of relative fiber motion are analyzed. The effect…
Cross sections for the displacement of lattice atoms by gamma rays for energies up to 5 Mev have been calculated. The principal contribution is found to come from the Compton effect, in which the atoms are displaced by electrons produced by the incident gamma rays. The calculations have been based on the assumption of…
SUMMARY: Over a hundred isolates which produced haloes around their colonies on dilution plates containing calcium carbonate or dicalcium phosphate have been obtained in pure culture from the root region of the oat plant. Of these, more than 50% were pleomorphic, and this group had the highest proportion of isolates w…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparation of the Ferrites BaFe12O19 and SrFe12O19 in Transparent Form1Lothar H. BrixnerCite this: J. Am. Chem. Soc. 1959, 81, 15, 3841–3843Publication Date (Print):August 1, 1959Publication History Published online1 May 2002Published inissue 1 August 1959https://pubs.acs.o…
The simple model for atomic displacements by electrons of Seitz and Koehler is used to calculate the total number of displaced atoms in germanium and silicon due to electrons and gamma rays of energies up to 7 Mev. The calculations are compared to reported experiments in the literature. Electron damage at energies bel…
The Lindemann melting rule is used to eliminate the elastic constant from the thermal conductivity formula proposed by Lawson. The thermal conductivity is thus obtained as a function of density, atomic weight, and melting temperature. The introduction of a dependence on bond character allows a major fraction of the av…
Trititanium pentoxide (Tia05) is dimorphic--a rapid, reversible phase transformation occurring at about 120 C. The high-temperature modification is of the anosovite type (slightly deformed pseudobrookite structure). It can be stabilized at room temperature by small contents of iron.
Abstract Films of amorphous polyethylene terephthala were drawn and heated to various extents. Intensity change of the infrared spectral bands resulting from these treatments were followed. There are more than seven bands which change their intensities by drawing, and sixteen bands affected by heat treatment. Exactly…
Oxygen ion mobility in the cubic fluorite‐structure phase having the composition Zr 0.85 Ca 0.15 O 1.85 has been directly determined by exchange measurements employing the stable isotope O 18 and mass spectrometer analysis. Measurements of electrical conductivity have been carried out as a function of both temperature…
The formula given by Moli\`ere for the scattering cross section of a charged particle by an atom, on which has been based the formula for the "screening angle" ${\ensuremath{\chi}}_{\ensuremath{\alpha}}$ in his theory of multiple scattering, has been examined and found to contain an inconsistent approximation in all o…
Thin sheets, removed by cleavage from the surface layers of mica exposed to fission fragments from uranium, have been examined in transmission in the electron microscope. Fission fragment tracks which are less than 300 A. in diameter and greater than four microns in length have been seen, superimposed upon a general b…
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An empirical equation form, approximating the apparent dependence of the strength of brittle polycrystalline specimens on the combined effect of porosity and grain size, has been developed from concepts and data in the literature. The form is shown to be applicable to data for thoria and chromium carbide specimens.
The total photoelectric cross sections of copper, molybdenum, silver, tantalum, and gold have been measured at 662 kev. A highly collimated beam of gammas from a Cs-137 source impinged upon a thin disk of a target material. Photoelectrons from a target were detected by a plastic scintillator subtending very nearly $4\…