Materials Literature
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Surface reaction kinetics for diamond growth by chemical vapor deposition (CVD) was investigated experimentally. The temperature dependence for the growth rate exhibited surface-reaction controlled kinetics with the activation energy of about 23 kcal/mol below 900 °C. The dependence of the growth rate on the other CVD…
Using a tight-binding, total-energy model, we have calculated relaxed surface atomic positions, surface-state energies, and densities of states for the reduced and stoichiometric (110) surfaces of rutile-structure tin dioxide (cassiterite). Both relaxed surfaces display a small rumple of the top atomic layer and small…
Abstract Cascade (dendritic) polymers are discrete, highly branched, monodisperse polymers that possess branching patterns described by a mathematical progression. A systematic nomenclature that accurately represents these molecules is described. © 1993 John Wiley & Sons, Inc.
The growth-sector dependence of fine structure in the first-order Raman diamond line is investigated for the first time in high resolution spectra taken from large isolated diamond single crystals grown using microwave plasma chemical vapor deposition on tungsten wire tips. The volumes of crystal beneath the (100) and…
In this Monte Carlo simulation the authors study the glass transition of a dense three-dimensional polymer melt using a lattice model (a bond-fluctuation model on a simple cubic lattice) that was highly optimized for a vector supercomputer. Long bonds are energetically favoured to create a competition between bond ene…
We present a tight-binding calculation of the interband optical transitions in semiconductor quantum dots (QD's). The calculated optical-absorption spectra are in good agreement with the existing experimental spectra of CdS and CdSe QD's. We establish a correspondence between the tight-binding (TB) energy levels and t…
Electron-energy-loss spectra from individual carbon nanometer-size tubes are presented. The bulk plasmon-loss (\ensuremath{\sigma}+\ensuremath{\pi}) peak seen at \ensuremath{\sim}27 eV in graphite undergoes systematic shift towards lower energy, as the tube size is reduced. The low-energy-loss plasmon (\ensuremath{\si…
Myosin I is present in Swiss 3T3 fibroblasts and its localization reflects a possible involvement in the extension and/or retraction of protrusions at the leading edge of locomoting cells and the transport of vesicles, but not in the contraction of stress fibers or transverse fibers. An affinity-purified polyclonal an…
It is interesting to study the surface electronic structure of uranium in the context of f-electron localization as the 5f shell is filled. Accordingly, we have used the film-linearized-muffin-tin-orbital method to calculate the surface electronic structure of \ensuremath{\gamma}-uranium with body-centered-cubic struc…
Abstract A novel artificial extracellular matrix derivatized with a cell adhesive peptide, Arg—Gly—Asp—Ser (RGDS) tetrapeptide, which is the central peptidyl sequence of the adhesive site of fibronectin, was designed. RGDS coupling was achieved via isocyanation of surface hydroxyl groups of poly(vinyl alcohol) (PVA) f…
Triammonium hydrogenbis(tetraoxoselenate), (NH 4 ) 3 H(SeO 4 ) 2 , M r =341.04, Z=3, λ(Mo Kα)=0.71073 A, F(000)=498. Phase I: trigonal, R3m, a=6.090 (1), c=22.759 (5) A, V=731.0 (2) A 3 , D x =2.32 g cm -3 , μ=68.7 cm -1 , T=355 K, R=0.0336 for 241 unique reflections with I >4σ(I). Phase II: trigonal R3, a=6.064 (1),…
Factors affecting the performance of crossflow filtration were investigated with a thin-channel module and yeast cells. In crossflow filtration of Saccharomyces cerevisiae cells cultivated with YPD medium (Yeast extract, polypeptone, and dextrose) and suspended in saline, a steady state was attained within several min…
The combined electron and hole mobility of a single-crystal type IIa natural diamond and a polycrystalline diamond film deposited by chemical vapor deposition (CVD) were measured using transient photoconductivity as a function of excitation density (1013–1017 cm−3) and temperature (120–410 K). In natural diamond the t…
Abstract Two hexafluoro‐substituted aromatic polyimides, 6FDA‐ p ‐PDA and 6FDA‐4,4′‐ODA, were synthesized. The influence of some synthetic conditions on physical properties and gas permeabilities of the 6FDA polyimide membranes were studied. Gas permeabilities and permselectivities of six different gases for the homog…
Abstract The fiber/epoxy resin adhesion increases after plasma treatment on ultrahigh molecular weight polyethylene (UHMW‐PE) fibers. The surface modification of UHMW‐PE monofilaments was studied using a combination of techniques: contact‐angle measurements, SEM, and pullout tests. The results may be summarized as fol…
Different structural models for solid argon clusters with more than 500 atoms, that have been proposed previously on the basis of energy considerations, but whose origin and growth histories are not well understood, are compared with other models that have been devised mainly to overcome these difficulties, at the exp…
An experimental study of the effect of disorder on the nematic to isotropic (N–I) transition of a liquid crystal is reported. Differential scanning calorimetry is used to monitor the N–I transition of p-azoxyanisole in a series of controlled pore glasses. An increase and a decrease in the N–I transition temperature is…
Abstract A model two‐step synthesis of a saturated hyperbranched hydroxyl‐terminated ester has been developed to show a synthesis route. Three different series of hyperbranched esters with different terminations have been synthesized to relate some of their properties to their structures. This route has then been used…
Ordered diamond films have been deposited on single-crystal silicon substrates via an in situ carburization followed by bias-enhanced nucleation. Textured diamond films with greater than 50% of the grains oriented D(100)//Si(100) and D〈110〉//Si〈110〉 were grown in both a horizontal and vertical microwave plasma chemica…
Phenyl phenoxyformate, C 13 H 10 O 3 , M r =214.2, orthorhombic, P2 1 2 1 2 1 , a=6.062 (2), b=7.242 (1), c=23.375 (4) A, V=1026.2 A 3 , Z=4, D x =1.387 g cm -3 , λ(Mo Kα)=0.71069 A, μ=0.92 cm -1 , F(000)=448, T=164 K, R=0.0384 for 1375 unique reflections with I>2σ(I). Diphenyl car bonate constitutes the simplest cong…