Materials Literature
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The quantitative determination of atomic hydrogen concentrations cH in the vicinity of hot filaments is performed with two-photon laser-induced fluorescence. The measurements yield atomic hydrogen concentration profiles up to 28 mm from the filament surface with a spatial resolution of about 0.5 mm. The nonequilibrium…
Using small-angle neutron-scattering techniques, the scaling laws between the thickness of a grafted polymer layer h, its graft density \ensuremath{\sigma}, and the molecular weight of the grafted chains M have been determined for polydimethylsiloxane chains end grafted on porous silica. The observed laws h\ensuremath…
Carbon bonding environments (measured by nuclear magnetic resonance spectroscopy) and compressive stress in plasma-deposited hydrogenated diamond-like carbon (DLC) films have been examined systematically as a function of substrate bias voltage. These results are related in terms of random network theory to show that h…
The Monte Carlo method is used to study three systems of fused hard spheres with length-to-width ratios ranging from 3·5 to 5·2. Spontaneous nematic alignment is observed only for the most elongated molecules. The isotropic data are compared with a theoretical expression due to Boublik and are fitted by a y expansion…
Analytical transmission electron microscopy, electron microprobe analyses, and singlecrystal x-ray diffraction data support the conclusion that high potassium contents, up to 1.5 weight percent K(2)O, of some diopside and omphacite inclusions from diamonds represent valid clinopyroxene compositions with K in solid sol…
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” opt…
Abstract Various amines were added to carbanilation reactions of cellulose samples with phenylisocyanate in an effort to aid the preparation of cellulose tricabanilates (CTCs) for determining molecular weight distributions (MWDs). However, the amines catalyzed the conversion of phenylisocyanate to its trimer phenyliso…
Abstract Nascent high‐molecular‐weight (UHMW) polyethylene (PE) samples of different origins show a rather high crystallinity of about 70–75% and contain both a major portion of orthorhombic extended chain crystallites and a minor portion of triclinic crystallites. The triclinic content is greater the higher the molec…
Abstract A viscometric approach to the formation of interpolymer complexes between a polyelectrolyte, polyacrylic acid, and a non‐ionic polymer, polyacrylamide, is investigated. The following method compares the reduced viscosity of the polymer mixture with an “ideal” value which results from the additivity of the red…
Substitution of Thr26 by Gln in the lysozyme of bacteriophage T4 produces an enzyme with greatly reduced activity but essentially unaltered stability relative to wild type. Spontaneous second-site revertants of the mutant were selected genetically; two of them were chosen for structural and biochemical characterizatio…
Abstract A phase separation model was used to simulate the morphologies obtained in a system consisting of a diepoxide based on bisphenol‐A diglycidylether cured with a cycloaliphatic diamine, in the presence of an epoxy‐terminated butadiene‐acrylonitrile random copolymer (ETBN). A detailed analysis of experimental fa…
Abstract The glass transition temperature ( T g ) of polyphenylene sulfide (PPS), and of several commercial and model PPS prepregs with aramid, carbon, and glass fibers was studied by means of differential scanning calorimetry. The T g of unreinforced PPS was found to range between 83–90°C, depending on source and mol…
Abstract Cellulose fibers were surface modified with polypropylene–maleic anhydride copolymer. The physical properties of such fibers were characterized by contact angle measurements, and the chemical structure was identified with ESCA and FTIR. ESCA showed that the modifying agent was localized at the surface of the…
Two phase mixtures of ZnS consisting of the hexagonal and the cubic phase have been prepared by hot-pressing at different temperatures. The optical properties of these two phase composites were measured in the far infrared. The difference in the index of refraction between the cubic and the hexagonal phases produced s…
The authors present the first experimental analysis of the chlorine-water distribution in the glassy and liquid state of LiCl.6D 2 O. The results are based on neutron diffraction experiments performed at a spallation source. Evidence of a fundamental structural change within the hydration shell around a chlorine ion i…
Vibrations of Sb on (110) surfacesof III-V semiconductors (InP,GaAs,GaP) were investigated by Raman scattering from the submonolayer range up to a few monolayers. Interface phonons, involving the epitaxial first monolayer of Sb and the upper substrate layer, are observed. They are clearly identified by their coverage…
The role of oxygen has been found to be very significant in the diffusion of Cu in Cu/TiNx/Al and Cu/TiNxOy/Al thin film structures. While no interdiffusion takes place in the Cu/TiNxOy/Al structure up to 575 °C, a substantial interdiffusion, with Cu and Al moving in opposite directions, has been found in the Cu/TiNx/…
Epilayers of transition metal dichalcogenides (TMDs) with two-dimensional structures can be grown with molecular beam epitaxy onto other TMDs substrates without regard to lattice matching. Although there is no strong bonding between the epilayer and the substrate, the van der Waals interaction between the two hexagona…
Thin carbon films were deposited by ion beam sputtering at temperatures of 77–1073 K. Using Rutherford backscattering spectrometry and electron energy loss spectroscopy, the trends in film density and bonding were examined as a function of deposition conditions. It has been found that film density and sp3 bonding char…
Measurements are reported of the electrical conductivity of iron vanadate glassy semiconductors over the temperature range 80-450 K. The data is analysed in the light of existing theoretical models of polaronic hopping conductions. The high-temperature behaviour is consistent with phonon-assisted hopping of polarons i…