Materials Literature
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In this paper we consider energy transfer among impurity molecules in disordered systems. We use the result of Gochanour, Andersen, and Fayer [J. Chem. Phys. 70, 4254 (1979)] for the generalized diffusion coefficient D(t) in terms of the decay function Φ(t), in conjunction with separate calculations of Φ(t) in the pai…
The point dipole interaction model for molecular polarizability recently proposed by Applequist, Carl, and Fung is modified by replacing isotropic atomic point dipoles with anisotropic atomic point dipoles. The modified formalism, which is invariant to coordinate transformations, requires an additional empirical param…
Cross sections for Rayleigh and Mie scattering on a roughned conducting surface are given. The Rayleigh scattering is strongly enhanced by roughness. Rayleigh and Mie scattering are found to interfere with each other. The experimental consequences for surface enhanced Raman Scattering (SERS) are discussed. (AIP)
The pyrolysis of organic dianhydrides (e.g., 3,4,9,10-perylenetetracarboxylic dianhydride) in an evacuated system results in the loss of hydrogen, CO, and CO2 and the deposition of a chemically inert, metallic-appearing mirrolike film. The films are highly conducting (σRT250 Ω−1 cm−1) and can evidence either metallic…
A molecule adsorbed on the surface of a conducting prolate ellipsoid will Raman scAtter with an enhanced cross section. The relevance of this fact to the phenomenon of surface enhanced Raman scattering (SERS) is discussed. (AIP)
The newer tetracyclines are defined as those tetracyclines available in the United States but not approved for veterinary use. These include demeclocycline, methacycline, doxycycline, and minocycline. Of these, doxycycline and minocycline appear to offer advantages that would render them useful in certain situations i…
It is shown on the example of the dielectric data for Er-doped CaF 2 that very slight departures from the true Debye response can be assessed very accurately using the analysis of the real part of the susceptibility. Given adequate precision of measurements, this method is far more sensitive than the plotting of the c…
Chemically deposited PbS thin films have been prepared for use as infrared detectors. A systematic and elaborate study using scanning electron microscopy shows that the structure and crystallite size are related to the photosensitivity. Both the role of chemical oxidant influencing the type of conductivity and morphol…
For pt.I see ibid., vol.13, no.13, p.2485 (1980). The valence band of V 2 O 5 , calculated by means of a tight-binding method, is analysed in terms of projected densities of states on the different atomic orbitals, allowing a discussion of the bonding properties. The dispersion of the energy bands is discussed in conn…
A tight-binding method enabling the calculation of the energy bands of compounds with a complicated crystal structure such as V 2 O 5 is presented. It is based on certain assumptions and limitations concerning the choice of interactions which have to be taken into account. Perturbation theory is used in order to obtai…
Abstract The ESR-behaviour of antiferromagnetic and almost stoechiometric CrN is thoroughly investigated above its Neél-point. For polycrystalline samples a spectroscopic splitting factor g =1.965 and a differential line width ⊿B = 56,7 mT is measured at room temperature. All resonance lines exhibit Lorentzian charact…
A computational program, based on a diffusion surface deposition of oxygen, has been developed and applied to the calculation of a mesh-packed cold trap. The results were compared with experimental data for a forced-life test that was carried out by internal introduction of sodium peroxide into the sodium loop. Good a…
Fifty-six bales of medium staple cotton were spun into 40s yarn to evaluate spinning performance. In a parallel effort, roving samples from each bale were tested on a single-end drafting tester that duplicates the Tru-Set drafting system used in spinning. Front-zone drafting force and force-vari ability measurements w…
Abstract The rate of transformation from helical to all‐ trans ‐planar polytetrafluoroethylene (PTFE) at high pressures has been determined by monitoring the Raman spectra of PTFE following pressure jumps from the stability field of PTFE II to pressures between 9 and 14 kbar at temperatures between 0 and −30°C. The tr…
Abstract 1 H NMR spectra of polyisoprene were assigned using polymers of isoprene-1,1,4,4- d 4 , isoprene-1,1,5,5,5- d 5 , and isoprene-4,4- d 2 polymerized with various catalysts. The methylene-proton signal at 2.1 ppm in cis -1,4- and trans -1,4-polyisoprenes was divided into H 4 - and H 1 -proton signals; H 4 reson…
The immobilization of some medically useful enzymes were studied by means of radiation-induced polymerization at -78 degrees C. Glucose oxidase and glucose peroxidase were immobilized in the form of thin membranes inside polyvinyl chloride tubes and on polyethylene films; these membranes showed considerable activity y…
Abstract As with polybutadiene and SBR compounds, filled and unfilled vulcanizates of natural rubber exhibit long transients in their linear thermal expansion response following sudden changes in temperature. This is particularly noticeable when the materials are prestretched well beyond the point of thermoelastic inv…
For pt.CXXXVII see ibid., vol.B35, p.2384 (1979). LiNO 3.3H 2O has been studied by neutron diffraction at 120 and 295 K. The final R(w.F 2) values are 4.5% (120K) and 4.9% (295K). The crystal structure found in a previous room-temperature X-ray study is confirmed: one water molecule is involved in six hydrogen bonds;…
In order to examine the relative contribution of surface and gas phase reactions to the exothermic conversion of a fuel-air gas mixture flowing over a catalytic surface, we have carried out a theoretical and experimental study of catalytic combustion under stagnation point flow conditions. In the presence of exothermi…
Abstract RbTaO 3 kristallisiert monoklin mit a = 9, 58 9 , b = 8, 50 5 , c = 8,13 5 Å, β = 94,8 7 °, Z = 8, Raumgruppe C2/m. Nach der Strukturaufklärung (Vierkreisdiffraktometerdaten, 4° ≤ Θ ≤ 33°. 1014 hkl, MoKα, R = 9,9%) liegen über Rb verknüpfte [TaO 3 ]‐Schichten vor, in denen Ta je zur Hälfte oktaedrisch und tet…