Materials Literature
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The effects of heteroatom addition on the nucleation of solid carbon in a low-pressure plasma reactor were investigated. Silane or diborane were added to acetylene mixed in hydrogen or argon. Oxygen was added to some of the diborane containing gas mixtures. Silane containing mixtures resulted in powder comprised of we…
The band gaps and exciton energies of CdS and GaP clusters are calculated for the first time using pseudopotentials. The calculated exciton energies of CdS over a wide range of cluster sizes are in excellent agreement with experiment. Furthermore, the exciton states of clusters with zinc-blende and hexagonal lattices…
The switching time (ts) for polarization reversal in ferroelectric films of PbZr0.53Ti0.47O3 and La-substituted PbTiO3 has been investigated. The films were prepared by spin-on and metalorganic decomposition followed by processing into ferroelectric capacitors having electrode areas ranging from 9 to 50 000 μm2. Pulse…
Two-dimensional molecular patterns were obtained by the adsorption of long-chain alkanes, alcohols, fatty acids, and a dialkylbenzene from organic solutions onto the basal plane of graphite. In situ scanning tunneling microscopy (STM) studies revealed that these molecules organize in lamellae with the extended alkyl c…
The structure of a 20-amino acid peptide inhibitor bound to the catalytic subunit of cyclic AMP-dependent protein kinase, and its interactions with the enzyme, are described. The x-ray crystal structure of the complex is the basis of the analysis. The peptide inhibitor, derived from a naturally occurring heat-stable p…
Using a mold for centrifugal casting as an example, discusses the types of apparatus and tools that are commonly affected by thermal fatigue during industrial processes, and examines the various factors that lead to such failure. Focuses on the performance of particular industrial components under d
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…
The complete COOH-propeptide of human alpha 1(I) procollagen was chemically synthesized as a series of overlapping subfragments which were then tested for their effect on extracellular matrix protein production by subconfluent human lung fibroblasts (HFL-1). One peptide (R11; residues 197-241) stimulated production of…
Large nonresonant third-order hyperpolarizabilities, γ1111, for solutions of three organic charge-transfer complexes in tetrahydrofuran have been measured. The values obtained for nonresonant γ1111 are 5.8×10−32 esu for Perylene/tetracyanoethylene, 1.2×10−32 esu for Pyrene/tetracyanoethylene, and 7.2×10−33 esu for Nap…
A precise definition for the crystallite orientation distribution function (codf) of cubic polycrystals is given in terms of the set of distinct orientations of a cube. Elements of the classical Fourier representation of the codf, in terms of (symmetrized) generalized spherical harmonics, are reviewed. An alternative…
A convenient method for calculating phonon frequencies at q=0 and macroscopic dielectric constants in cubic insulators is developed in the framework of the density functional method: it is applicable to the case of both local and non-local pseudopotentials. The equilibrium unit-cell volume, bulk modulus, equation of s…
Space-charge-limited hole currents in nominally undoped diamond thin films have been studied using thin, highly boron-doped (p+) diamond layers as injecting contacts. The results obtained from these p+-p-Si structures have been analyzed to determine, for the first time, the bulk distribution of localized states N(E) i…
The activation energies for diamond growth were determined by an advanced hot filament chemical vapor deposition (AHF-CVD) method, which accurately controls the substrate temperature independently against other CVD parameters. The activation energies, as determined from an Arrhenius plot, were 22–24 kcal/mol in the ra…
The effects of surface pretreatments on nucleation and growth of chemical vapor deposited diamond films were studied. The pretreatments included scratching with diamond grit, coating with a low vapor pressure, high thermal stability hydrocarbon oil, and coating with a 100–200-Å-thick layer of evaporated carbon. The ef…
A Nd-YAG laser giving 5 ns, 266 nm pulses was used to melt and subsequently quench thin, pure metallic films on a liquid Al/Al2O3 substrate at 1010–1012 K s−1. Transmission electron microscopy together with electron diffraction was used to study the competitive nucleation and growth behavior of the crystals from the u…
We report the observation of a giant resonance in the Cu 2p resonant-photoemission spectra of CuO. The study allows the unambiguous identification of the local Cu 3${\mathit{d}}^{8}$ configuration in the valence-band photoemission spectrum, providing conclusive evidence for the charge-transfer nature of the insulating…
Abstract Polypyrrole was synthesized using two different methods of chemical synthesis to obtain a product with different electrical conductivity values. The two products were found to possess about the same ability to bind protein. After prolonged exposure to aqueous solutions of different ionic composition and at di…
Abstract Melt blends of nylon with poly(styrene‐ co ‐maleic anhydride) (SMA) were prepared in a twin‐screw extruder. Viscoelastic properties of the melt and morphological, thermal, and mechanical properties of the blends were determined. Fourier‐transform infrared (FTIR) spectroscopy measurement indicated reactions be…
Abstract Kinetics of gelation for aqueous solutions of poloxamers 407 and 288 were determined using pulse shearometry. The principle of this method for determining the shear modulus of a semisolid was based on generation of a torsional force that is transmitted through the poloxamer sample at discrete time intervals.…
Abstract Experimental results on plasma treatments of polysulfone and polyetherimide to improve the wettability of these polymers are presented. The plasma is characterized by optical emission spectroscopy. The wettability of the polymer surfaces were checked by contact angle measurements and ESCA is used to compare t…