Materials Literature
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Abstract A study has been made of surface recombination of hydrogen atoms on various transition metals. Hydrogen atoms were produced in the electric discharge tube by use of an alternating current. In order to prevent the reacting gas from reaching the undesired part of the sample, a method which may be called “an eff…
A new method of perturbation theory is developed in the simple LCAO MO treatment of conjugated molecules. Several useful equations are derived, giving orbital energy, electron density, and bond order of the perturbed system.
The kinetic equations describing a general chain mechanism of depolymerization are solved at steady state for a polymer having an initial ``most probable'' molecular weight distribution. Chain scission initiation, end group initiation, depropagation, intermolecular chain transfer, and several types of termination are…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFactors Affecting the Non-Newtonian Viscosity of Rigid Particles1Jen Tsi YangCite this: J. Am. Chem. Soc. 1959, 81, 15, 3902–3907Publication Date (Print):August 1, 1959Publication History Published online1 May 2002Published inissue 1 August 1959https://pubs.acs.org/doi/10.10…
Abstract The adsorption of polystyrene from toluene solution on a carbon black has been studied at 25°C. under varying conditions of dryness. The isotherm for adsorption on the relatively dry carbon black exhibited a characteristic steep initial rise as a function of concentration and attained a saturation value. Larg…
High stresses arise in sintered β‐eucryptite (Li 2 O. Al 2 O 2 ‐2SiO 2 ) during cooling from the firing temperature because of its extreme anisotropy of thermal expansion. These stresses cause extensive fracturing of the crystals, resulting in abnormally low mechanical property values at room temperature. During rehea…
Abstract The aqueous polymerization of tetrafluoroethylene initiated with ammonium persulfate in neutral or relatively weak acid solutions leads to polymer containing carboxyl end groups. The conversion of this endgroup to the sodium salt and its pyrolysis to the terminal olefin was followed, using infrared absorption…
A comparison has been made of transmission electron microscope observations on polycrystalline aluminium deformed in tension or by fatigue. The dislocation distribution in aluminium deformed in tension, was studied as a function of stress. At stresses up to 3 kg mm−2 the distribution is extremely irregular; at higher…
A model for low-temperature dislocation motion is developed using the concept of nucleation and growth of kinks in dislocations lying in Peierls potential troughs. The model is compared with existing experimental data.
Die Leitfähigkeit σ oxydisdier Halbleiter in Gegenwart von Sauerstoff wird bei hohen Temperaturen und nicht zu großen Störstellenkonzentrationen nicht allein durch die thermische Abspaltung von Trägern aus den Störstellen, sondern in entscheidendem Maße auch durch eine von der Temperatur T und vom Sauerstoffdruck P O2…
A portion of the system Na/sub 3/PO/sub n4/-CaCO/sub 3/)-H/sub 2/0 was investigated at low temperatures. The formation of a carbonate apatite by phosphate replacement of calcite in alkaline solutions and the structural positions of the carbonate groups are discussed. Data indicate calcite replacement by low concentrat…
The characteristic K-radiation employed in x-ray diffraction consists of the bichromatic wavelengths λ(α1) and λ(α2). In practice the observed diffraction pattern is the superposition of the patterns of the two components. In many cases it is necessary to determine the diffraction pattern for a single wavelength. An a…
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.