Materials Literature
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Abstract Racemization of optically active oligo- and poly(quinoxaline-2,3-diyl) derivatives with a single screw-sense, prepared by the polymerization of 3,6-diaryl-1,2-diisocyanobenzenes catalyzed by methylpalladium(II) initiator, was investigated. Pentameric and hexameric oligomers with a living palladium terminus we…
The birefringence and refractive indices of several liquid crystalline structures were measured throughout the visible wavelength region (400–900 nm) at different temperatures. Mixtures composed of members of the same homologous series were used in order to achieve the nematic phase at room temperature. Data on 28 mix…
We describe the experimental properties of metastable domains associated with the presence of an Inversion Wall (IW) and observed with homeotropically anchored nematic and cholesteric liquid crystals sandwiched between parallel glass plates. Such a distorted situation, stabilized by the application of an electric fiel…
By analytically solving some simple models of phase-ordering kinetics, we suggest a mechanism for the onset of nonequilibrium behavior in colloid-polymer mixtures. These mixtures can function as models of atomic systems; their physics therefore impinges on many areas of thermodynamics and phase ordering. An exact solu…
Diamond films of various thicknesses (1.5–12 μm) deposited on Pt (111) by microwave enhanced chemical vapor deposition (CVD) were studied by scanning electron microscopy (SEM) observation and x-ray diffraction pole figure measurements. The dependence of the surface morphology and structure of the films on the film thi…
We have studied the structure of bulk amorphous GaSb using the extended x-ray-absorption fine-structure (EXAFS) technique over the temperature range from 80 K to 293 K. The possibility of the presence of chemical disorder has been explored throughout the temperature range. The configurational (static) contribution to…
It is shown that the activation energy of a chemical reaction depends mainly on the difference between the hardness of the initial state of a reaction and the hardness of the transition state, that these two quantities may be estimated from the softnesses of the reacting molecules and the softnesses of the molecular f…
The surface-enhanced Raman scattering (SERS) spectra of L-phenylalanine were examined in the near-infrared region using silver colloid solutions. It was shown that near-infrared SERS (NIR-SERS) was not detected for L-phenylalanine in a normal silver colloid solution, whereas in the visible region a distinct SERS inten…
The probability of the presence of stacking faults in the β-form single crystals of syndiotactic polystyrene, which were grown isothermally from a dilute solution at a temperature ranging from 150 to 210 °C, was estimated from the mean half-breadth of the streaked reflections. The probability was also estimated by cou…
Reactions of nitridochromium(V) porphyrins with chromium(III) porphyrins resulted in reversible, inter-metal nitrogen atom transfer between the two chromium porphyrin complexes. The progress of these reactions was followed spectrophotometrically. Kinetic analysis of the spectral data obtained over time for a variety o…
Due to the discrete directional nature of processes such as crystallographic slip, the orientation of slip planes relative to a fixed set of loading axes has a direct effect on the magnitude of the external load necessary to induce dislocation motion (yielding). The effect such geometric or textural hardening has on t…
We have found, at high EM magnification, on ultrathin sections of shock-frozen, freeze-dried, embedded pieces of the developing hard tissues, that the primary crystallites consist of strands composed of nanometer-sized apatitic islands, which rapidly coalesce to needles and afterward to platelets. By small-area electr…
In this paper are presented data on the preparation and characterization of different oxide electrodes. RuO 2 –TiO 2 , IrO 2 –TiO 2 , and SnO 2 –Sb 2 O 5 mixed-oxide films have been taken as model systems. For the first, the traditional preparation method based on the pyrolysis of precursor salt deposits was adopted.…
New cyclolinear polymers from bifunctional organic molecules and cyclotriphosphazenes containing two reactive groups have been synthesized. The reaction between 2,2-bis(4-hydroxyphenoxy)-bis[spiro(2′,2“- dioxy-1′,1”-biphenylyl)]cyclotriphosphazene 3, obtained by the reaction of 2,2-bis(4-methoxyphenoxy)- bis[spiro(2′,…
Recent results from low-frequency Raman scattering experiments on different types of glass formers are discussed. In particular, fast relaxations above T g in the frequency range 1010Hz < v < 1013Hz are described. Both fragile and non-fragile glass formers exhibit similar dynamics which qualitatively can be reproduced…
The electrochemical polarization behavior of the copper‐containing Al 2024‐T3 alloy in deaerated 0.01 M NaCl saturated with a number of solid inhibitors demonstrates that one of the compounds examined, barium metaborate, exhibits an inhibiting power in excess of that of zinc chromate. Electrochemical polarization of a…
We present spectra of three M subdwarfs which are common proper motion companions to F or G subdwarfs of known metallicity. The assumption that the companions have the same composition allows us to test the Gizis (1997, AJ, 113, 806) M subdwarf classification system and its correspondence to metallicity. The results a…
Equilibria constants for the simultaneous liquid-phase syntheses of methyl tert- butyl ether (MTBE) and ethyl tert- butyl ether (ETBE) were determined experimentally in the temperature range 313−353 K at 1.6 MPa. To achieve etherification equilibria, the macroporous sulfonic acid resin Bayer K-2631 was used as the cat…
To derive the absorbed dose to water from a standard of absorbed dose to graphite, the metrology laboratories which apply such a method usually make use of cavity ionization chambers as transfer instruments. In addition, the BNM-LPRI has tested, as such instruments, two types of Fricke dosimeter in its cobalt-60 beam.…
Abstract We report on the atmospheric corrosion of different cast statue bronzes in humid air containing ppb levels of SO 2 and SO 2 +NO 2 . In addition, copper, tin, zinc, and lead samples were studied in these environments. The samples were exposed to synthetic atmospheres with careful control of pollutant concentra…