Materials Literature
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Abstract Proton NMR second moments and spin-lattice relaxation times of polycrystalline C(NH 2 ) 3 PbI 3 and [C(NH 2 ) 3 ] 2 PbI 4 were studied in a wide temperature range. The order-disorder character of the existing solid-solid phase transitions was confirmed and for tetraiodoplumbate a new phase transition at 170 K…
Physicochemical and structural properties of microbial cell surfaces play an important role in their adhesion to surfaces and are determined by the chemical composition of the outermost cell surface. Many traditional methods used to determine microbial cell wall composition require fractionation of the organisms and c…
Secondary electron emission properties from crystalline and polycrystalline diamond films containing different boron concentrations were measured. The secondary electron yields δ were high. Yields were independent of incident beam angle and crystallographic orientation. The secondary electron yields were greatest for…
Transmission X-ray microscopy makes it possible to investigate biological specimens, i.e. cells and organelles, in their natural wet environment. The main processes determining the contrast in X-ray microscopy are photoelectric absorption and phase shift. X-ray microscopic experiments can therefore be carried out in b…
Sialons (Si−Al−O−N) are useful as engineering components because they combine the toughness of silicon nitride with phase stability. Competing reactions occur during conventional processing, making it difficult to form single-phase material without high-temperature/long-time heat treatments. Thermochemical insights in…
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…