Materials Literature
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Abstract Surface grafting of polymeric materials, such as films and fibers, may improve their reactive surface properties. Polypropylene active sites that should initiate a surface postgrafting can be formed by either nitrogen cold plasma or an electron‐beam irradiation. The plasmamodified polymer surface is cross‐lin…
We report results from cathodoluminescence spectroscopy of boron nitride films grown on Si(100) substrates by ion-source-assisted magnetron sputtering of a hexagonal BN target. Three main peaks are observed in the near-band-gap region for hexagonal boron nitride films at energies of 4.90, 5.31, and 5.50 eV. We also re…
Microcrystalline silicon (μ-Si) thin films were anodized in dilute HF solutions in the same manner as forming porous materials. It is demonstrated for the first time that the anodized μ-Si thin films show strong violet luminescence (415 nm) at room temperature. Visible green and red emissions were also observed accomp…
Calorimetric and optical reflectivity studies on free-standing partially fluorinated liquid-crystal films have revealed novel melting phenomena. The smectic-$A$-isotropic transition occurs through a series of layer-thinning transitions, causing the films to thin in a stepwise manner as the temperature is increased. Th…
We have performed molecular dynamics simulations of a supercooled atomic liquid. The self-intermediate-scattering function in the $\ensuremath{\beta}$-relaxation regime has a power-law time dependence and temperature dependence consistent with the mode-coupling-theory prediction of a von Schweidler law, with exponents…
In an effort to prepare crystals and determine the structure of alpha-thrombin complexed to a synthetic peptide inhibitor (MDL-28050) of the hirudin 54-65 COOH-terminal region, it was discovered that the crystals were not those of the complex but of gamma-thrombin. Gel electrophoresis studies revealed that autolytic d…
In a simple one-pot reaction the host-guest compounds 1 (white spheres FeIII; black = FeII; gray = NH; angled rods = 2: R = Me, Et) are accessible in gram quantities by self-assembly. They are the only fully characterized redox isomers whose cyclic voltammograms display four quasi-reversible waves and whose mixed-vale…
The substitution pattern determines whether distilbenylazobenzene compounds 1 or their subsequent products, the dihydrocinnolines 2, are isolated in the cobalt-catalyzed solvent-free reaction of azo compounds with diphenylacetylene. For several derivatives a photochromic equilibrium exists between the two forms.
No bonding interactions exist between the three interpenetrating framework structures in 1, and all of the two-dimensional networks are constructed by coordinate linkages-these two principles describe the structure of 1 (shown schematically on the right). Compound 1 was prepared from K2[Cd(CN)4], Ag-NO3, and pyrazine…
Liquid-Crystalline behavior over a wide temperature range and reversible phase transitions are observed for the polymer network 1, which is held together by hydrogen bonds between benzoic acid and pyridyl units
Up to fourth-generation neutral phosphorus-containing dendrimers are prepared in good yields in the synthesis outlined here. The only byproducts are NaCl and H2O, and the products contain highly reactive functional groups along the periphery. The first-generation dendrimer is shown on the right.
Abstract The role of metalloenzymes in important biological transformations has attracted increasing attention over the past several decades. Of the many chemical transformations mediated by enzymes, few are as challenging as multielectron redox reactions. Recent studies have revealed a partial structural and mechanis…
Mechanisms of guanosine triphosphate (GTP) hydrolysis by members of the G protein alpha subunit-p21ras superfamily of guanosine triphosphatases have been studied extensively but have not been well understood. High-resolution x-ray structures of the GTP gamma S and GDP.AlF4- complexes formed by the G protein Gi alpha 1…
The ability to produce high quality films in an electron cyclotron resonance reactor is dependent on the gas distribution system. In an effort to understand gas distribution effects, a variety of gas ring injection systems were implemented during silicon nitride growth. Film refractive index, uniformity, and stress we…
The beam-bending method is very useful for the viscosity determination of glasses, but the time spent to run the measurement is usually very long. The present note describes the performance of an improved beam-bending viscosimeter at the support stand and loading rod to get the faster measurements of high viscosity gl…
Abstract The structure of perfluorinated ionomer membranes (Nafion®) incorporating large organic cations, tetraethylammonium (TEA+) and 1,1′-dialkyl-4,4′-bipyridinium cations (CnV2+, n = 3 and 8), is studied using small-angle X-ray scattering (SAXS). For TEA+- and C3V2+-form membranes, the SAXS maxima show the presenc…
Yellow zirconium silicate is a promising substitute for cadmium pigments used in plastics. However, the incorporation of zircon pigment in HDPE without loss of impact strength is required. By introducing the untreated pigment in the polymer, the impact strength reduces to 60% of the value for the unfilled polymer. Dif…
Abstract An experimental study was carried out to demonstrate the possibility of compatibilising blends of polyvinylidenefluride with minor amounts of fluorosilicone elastomer, thereby achieving better low temperature ductility without excessively reducing the melting point and degree of crystallinity of the fluoropol…
X-ray photoelectron spectroscopic (XPS) studies of inP surfaces subjected to a new method of hydrogen plasma treatment are reported here. The XPS analysis shows that the usually observed phosphorus loss can be reduced by the use of a 'sacrificial' inP immersed in the hydrogen plasmawith the test InP Sample kept away f…
Self-diffusion along the [112] Shockley parital dislocation pair (self-pipe-diffusion) in Au is studied with Nos\'e-Hoover molecular dynamics (MD) using the many-atom Ackland-Tichy-Vitek-Finnis model. We find the following formation energy difference between interstitials (i) and vacancies (v) at partial dislocations:…