Materials Literature
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Arc jet deposited films of diamond have been patterned using Au or photoresist masks and electron cyclotron resonance (ECR) O2 discharges. To achieve anisotropic features, additional RF-induced DC biasing of the sample is necessary. Diamond etch rates of 2000 Å/min were obtained for 1 mtorr, 400 W O2 discharges with −…
ABSTRACT Researchers have recently determined that capillary pressure plays a dominant role in controlling the texture, and hence the rheology, of foam flowing through a porous matrix. Of particular interest, the capillary pressure was found to reach a characteristic value, the limiting capillary pressure, at a relati…
The stabilities and growth kinetics of monoclinic celsian feldspar (BaAl2Si2O8) and of cymrite (BaAl2Si2O8.nH2O, where 0 < n < 1) have been investigated in the system BaO-Al2O3-SiO2-H2O at pressures up to 10 kbar and temperatures up to 800-degrees-C. Synthesis experiments and growth-rate studies using gel starti…
Tryptophan synthase from enteric bacteria is an alpha 2 beta 2 bienzyme complex that catalyzes the final two reactions in the biosynthesis of L-tryptophan (L-Trp) from 3-indole-D-glycerol 3'-phosphate (IGP) and L-serine (L-Ser). The bienzyme complex exhibits reciprocal ligand-mediated allosteric interactions between t…
Ammonia (NH3) and nitrogen (N2) were added to the hydrocarbon precursor 1,3 butadiene (C4H6) during rf plasma deposition of hydrogenated amorphous carbon (a:C-H) films. The effect of the additives on the film characteristics was determined by IR spectroscopy, solid state 13C cross polarization magic angle spinning nuc…
The critical dynamics near the consolute point of a relatively low molecular weight asymmetric critical binary polymer mixture is studied with dynamic light scattering. In contrast to a single exponential decay showing a critical slowing down, as has been reported for another low molecular weight polymer blend, we obs…
A combiation of video polarization microscopy and extensive digital line pattern analysis has been invoked to examine in quantitative detail the transformation of a lamellar into a ``labyrinthine'' magnetic-stripe domain pattern. The evolution of disorder is found to be mediated by a sequence of transverse, ``smectic'…
The mean-square displacement 〈\ensuremath{\Delta}${\mathit{r}}^{2}$(\ensuremath{\tau})〉 of particles in concentrated suspensions is measured at times sufficiently short to observe the transient nature of hydrodynamic interactions. For all volume fractions \ensuremath{\varphi}, the velocity autocorrelation function dec…
Substantial thinning or polishing of diamond films is a nontrivial problem because of the extraordinary hardness of diamond. In this letter, we report the observation of massive thinning of CVD diamond film (from ∼220 to ∼120 μm thickness) by simple diffusional transfer of carbon from diamond to iron foil at 900 °C. T…
Sputter-deposited SiO(X) (where X between 1.9 and 2.0) thin film coatings have been found to be durable to atomic oxygen. Such coatings will be used to protect polyimide Kapton photovoltaic array blankets from atomic oxygen attack in low earth orbit (LEO) on the Space Station Freedom (SSF). Monte Carlo modeling of ato…
Thermopower and electrical conductivity studies of copper substituted Mg-Al ferrites are undertaken over the temperature range 300 to 700 K. On the basis of the sign of the Seebeck coefficient (S), the ferrites under study can be considered as n-type semiconductors. A model is arrived at using Seebeck coefficient data…
The transport properties of undoped and copper-doped indium oxide and indium tin oxide ceramics are investigated. The correlation between density, carrier concentration, and mobility is analysed. The density of IO ceramics can be considerably increased by copper doping and approaches that of single crystals for 5 mol%…
The report covers the following themes: SOFC chemistry, properties of SOFC gases and materials, electrochemistry, electric current flow in SOFC elements, SOFC configurations, mass flow phenomena and linearized SOFC performance analysis. figs., tabs., 27 refs.
Abstract The pyrolysis kinetics of highly crosslinked polymethylsiloxane (PMS) was investigated by thermogravimetric analysis (TGA) under both isothermal and elevated temperature conditions with several environmental gases, such as oxygen, nitrogen, air, and helium. A non‐chain‐scission mechanism composed of initiatio…
We report here selective deposition and fine-scale patterning of hot filament deposited diamond films by the use of pulsed laser irradiation on silicon and copper substrates. The substrates were abraded with diamond and alumina powders before hot-filament chemical vapor deposition. A drastic enhancement in diamond nuc…
We have performed an extensive theoretical investigation of amorphous phosphorus (a-P) using the molecular-dynamics--density-functional method. The energy surfaces and forces for 124 atoms in a constant-volume simple cubic cell were calculated using the density-functional formalism, with a local-density approximation…
We study the adsorption of grafted polymer layers on a planar surface parallel to the grafting surface. The layer consists of two types of chains: nonadsorbed chains with a free end and adsorbed chains forming bridges between the two plates. In the limit of strong adsorption a dead zone exists in the vicinity of the a…
Abstract Formulations containing 4 parts cornstrach, 5 parts poly(ethylene‐ co ‐acrylic) (EAA), 1 part urea, and 1.6 parts of either water or aqueous ammonia were extruded at either 110–120°C or 150–160°C; and the resulting extrudates were then extrusion‐blown into films. Complex formation between EAA and starch was m…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDetermination of pH with surface-enhanced Raman fiber optic probesKen I. Mullen, DaoXin. Wang, L. Gayle. Crane, and Keith T. CarronCite this: Anal. Chem. 1992, 64, 8, 930–936Publication Date (Print):April 15, 1992Publication History Published online1 May 2002Published inissu…
Abstract X‐ray diffraction, CP/MAS C‐13 NMR, DSC, FTIR and fluorescence microscopy have been used to study the structure, compatibility, and morphology of films made from starch, poly(ethylene‐ co ‐acrylic acid) (EAA), and polyethylene (PE) before and after exposure to a mixture of highly amylolytic bacteria. The comp…