Materials Literature
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Although polyethylene is essentially nonbiodegradable, it was found that copolymers of ethylene and 2-methylene-1,3-dioxepane prepared by a high pressure free radical solution polymerization were indeed biodegradable. Most synthetic polymers are not biodegradable because they have not been on the earth long enough to…
The absolute energy of the Lyman- alpha 1 line of hydrogen-like krypton has been measured with an accuracy of 36 p.p.m. The ions were produced at GANIL (Caen) and the X-rays emitted in flight detected with a flat crystal spectrometer. The (1s) Lamb shift of hydrogen-like krypton has been found to be 11.95+or-0.5 eV in…
Absolute elastic and inelastic differential cross sections for electrons scattered from methane and ethane have been measured for incident electron energies from 7.5 to 20 eV and scattering angles from 32 degrees to 142 degrees . The measurements were made using an electron spectrometer, incorporating hemispherical el…
The hindered amine story is an interesting success story involving participation by scientists throughout the world. The success of hindered amines has partly been due to the free exchange of information among scientists, so that the accomplishments of one group, studying stable free radicals, could be picked up by th…
It is shown that a decaying vacancy is able to give an isolated line in an atomic or molecular photoelectron spectrum although the usual condition of validity of the quasi-particle approximation is violated. A more general condition is proposed which is based on the ability of the one-hole Green's function expansion i…
The authors have developed an arbitrary-collision sampling technique for Monte Carlo calculations of the diffusion term in the density gradient expanded energy distribution functions. The technique is shown to provide for an alternative and accurate Monte Carlo calculation of the diffusion coefficients. Comparisons of…
The mechanism of irreversible thermoinactivation of an enzyme has been quantitatively elucidated in the pH range relevant to enzymatic catalysis. The processes causing irreversible inactivation of hen egg-white lysozyme at 100 degrees C are deamidation of asparagine residues, hydrolysis of peptide bonds at aspartic ac…
Recent studies of the adsorptive and catalytic properties of magnetite (Fe 3 O 4 ) are discussed with respect to the water-gas shift reaction (WGS) in this review article. Proposed mechanisms are examined, and the properties of the active sites required for these mechanisms are considered. Kinetic relaxation measureme…
Alkali and barium hydroxide promotion of the Cu/ZnO methanol synthesis catalysts has been investigated with the following results: (i) at low temperatures, high H 2 /CO ratios, water-free and CO 2 -free synthesis gas, the alkali promote methanol synthesis rates in the order Cs>Rb>K>Na>Li; (ii) the alkali hydroxides ar…
Abstract 11,11,12,12‐Tetracyan‐9,10‐anthrachinodimethan [ 3a , X = C(CN) 2 ] besitzt im Kristall eine stark von der Planarität der Stammverbindung Anthrachinon abweichende Geometrie. Der Winkel zwischen den beiden Benzoanellanden beträgt 145°; die Dicyanmethylen‐Einheiten sind entgegengesetzt gefaltet und schließen ei…
A microdynamic theory for the self-diffusion coefficient, which involves a wave-number-dependent viscosity, eta (q), is successfully tested on a hard-sphere system. The models the authors introduce for eta (q) are adapted to the Lennard-Jones fluid. New molecular dynamics data for the relative diffusion coefficient, i…
Stage purity and staging transitions of potassium-graphite intercalation compounds have been investigated in situ by high-resolution x-ray scattering. The positions and profiles of ($00L$) Bragg reflections indicate staging disorder in thermal equilibrium for all compounds larger than stage 2, which increases with inc…
We report electron-microscopy and high-resolution x-ray-scattering measurements of rapidly quenched ${\mathrm{Al}}_{6}$Mn. The electron-diffraction pattern shows icosahedral symmetry. Peaks in the x-ray-diffraction pattern can be indexed to a mixture of fcc Al and a phase whose reciprocal lattice is described by a sum…
A description is given of basic regularities in the formation of domains and twins during phase transformation involving movement of a single plane phase boundary.
The Burgers vectors of secondary grain boundary dislocations, forming networks in near ~9, ~27a, ~27b and ~81a grain boundaries in polycrystalline specimens of a Cu +6 at. % Si alloy, have been determined using the technique of image matching, which involves a comparison of experimental and theoretical electron microg…
Surfactant is painted partially on a cylindrical insulator having a "back-side" (Inner) electrode, to change the distribution of the accumulating surface charge (residual charge) generated by ac partial discharge. The surfactants used are Neogen T®, Catiogen L®, or Tween 20®; the insulating material is polyvinyl-chlor…
Abstract Die neue Verbindung Na 6 Si 2 Se 8 kristallisiert monoklin in der Raumgruppe P2 1 /c (Nr. 14) mit den Gitterkonstanten a = 727,1(3) pm, b = 1700,7(5) pm, c = 1378,3(4) pm, β = 99,44(8)°. In der Struktur sind zwei SiSe 4 ‐Tetraeder über eine Se–Se‐Bindung zu diskreten [Si 2 Se 8 ] 6− ‐Anionen verknüpft.
Abstract Both boron nitride and boron carbide were synthesized by the pyrolysis of the boric acid/1,2,3-propanetriol condensation product above 1300 °C in N2, whereas the thermal treatment in an Ar flow yielded boron carbide.
Synopsis Image analysis provides a practical method for studying the cutaneous relief and better understanding of the formation of wrinkles during ageing and their regression induced by an anti-wrinkle product. Quantimet 900 degrees allows a fully automated analysis of 40 replicas of skin surface per cycle of 6 h. The…
An atomistic model has been used to calculate the dipole tensor of vacancies and impurity-vacancy (IV) pairs in ionic crystals. The program PDINT, developed for f.c.c. ionic crystals and based on a generalized Mott-Littleton procedure, was used. Two methods of evaluating dipole tensors of defects were investigated, th…