Materials Literature
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Abstract High resolution fluorine‐19 NMR spectra of polyfluoroaromatic compounds dissolved in deuterated dimethyl sulphoxide were measured and substituent shielding parameters were derived. These parameters were compared with the values observed in deuterated chloroform solutions and used to identify fluoroaromatic co…
A composite of titanium aluminide, reinforced with ZrO2 toughened Al2O3 fibers, has been produced by pressure casting. The stability of the microstructure during vacuum and air annealing was investigated by scanning and transmission electron microscopy (TEM). Processing resulted in partial dissolution of ZrO2 of the f…
Laser pyrolysis offers a means of extending solid free‐form fabrication to polymeric precursors. Laser pyrolysis of polycarbosilane (PCS) produces controlled β‐SiC shapes with nanometer grain size although properties are currently limited by high porosity. By the addition of filler powders, either inert or reactive, c…
Heat capacities and ac conductivities of AgI-based fast ion conducting glasses of AgI-${\mathrm{Ag}}_{2}$O-${\mathrm{P}}_{2}$${\mathrm{O}}_{5}$ and AgI-${\mathrm{Ag}}_{2}$O-${\mathrm{B}}_{2}$${\mathrm{O}}_{3}$ systems with different P-O or B-O network structures but with the same AgI concentration of 1.55\ifmmode\time…
Abstract Using asymptotic expansion and numerical analysis, we demonstrate how the step‐response ignition time of an automobile catalytic converter depends on the ratio of the reaction rate to the interphase heat‐transfer rate, as measured by a key Damköhler parameter χ and the degree of monolith subcooling ŋ.In the r…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTime-Resolved SERS Study of Direct Photochemical Charge Transfer between FMN and a Ag ElectrodeWei Zhang, Alberto Vivoni, John R. Lombardi, and Ronald L. BirkeCite this: J. Phys. Chem. 1995, 99, 34, 12846–12857Publication Date (Print):August 1, 1995Publication History Publis…
Abstract Le test de microactivité (MAT), utilisé pour comparer les catalyseurs de craquage, fonctionne avec un réacteur approximativement piston, isotherme et non stationnaire. Les rendements à la sortie d'un tel réacteur sont calculés dans le cas d'un modèle cinétique à familles (lumps), d'une grande expansion molair…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTQuantitative Analysis of Brewster-Angle Microscope Images of Tilt Order in Langmuir Monolayer DomainsMei-Wei Tsao, Thomas M. Fischer, and Charles M. KnoblerCite this: Langmuir 1995, 11, 8, 3184–3188Publication Date (Print):August 1, 1995Publication History Published online1…
Five new pregnane glycosides, taiwanosides A [1], B [2], C [3], D [4], and E [5], together with wilfosides C1N [6], C2N [7], M1N [8], and K1N [9], were isolated from the roots of Cynanchum taiwanianum. Their structures were determined on the basis of spectroscopic and chemical evidence.
We present a complete map of the boundaries of stable plastic deformation characterized by critical stresses σ i (i = 1, 2, 3), for dilute f.c.c. CuMn polycrystals. Achieving this objective required systematic studies of tensile deformation curves as influenced by the following parameters: solute concentration (0.63 a…
Thermal behavior and morphology of blends prepared by solution casting of mixtures of chitosan and poly(ethylene oxide) were studied by means of differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The preliminary results indicate that both melting point and crystallinity depend on the compo…
Optical birefringence of the liquid crystal induced in its isotropic phase by low concentration polymer networks (1--4 % by weight) is used to estimate the internal surface area of the network and its order parameter. The results show conclusively that the polymer networks are finely distributed down to the nanometer…
Gallium is a metal that literally melts in your hand. It has low toxicity, near-zero vapor pressure, and a viscosity similar to water. Despite possessing a surface tension larger than any other liquid (near room temperature), gallium can form nonspherical ...Read More
An ab initio molecular-dynamics simulation of liquid boron is presented. At the density \ensuremath{\rho}\ensuremath{\sim}2 g ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ and the temperature T\ensuremath{\sim}2600 K, icosahedra are destroyed although atoms still form an open packing with sixfold coordination. Moreover,…
Abstract X‐ray photoelectron spectroscopy was used to compare several pretreatments of aluminium surfaces used in aerospace and aircraft industry. These anodizing processes, which aim at preparing the metal surface for adhesive bonding or painting, all lead to the formation of an aluminium oxide layer. A set of alumin…
The brazing of ZrO 2 ceramic to 1Cr18Ni9Ti stainless steel and to itself was performed using Ag 57 Cu 38 Ti 5 filler metal under a vacuum of 7 × 10 ‐3 Pa. The effects of interlayer copper on the ceramic to stainless steel joint strength, and the brazing temperature (1073 to 1323 K) and holding time (0 to 60 min) on ce…
The orientation-phase-space-averaged excess volume associated with grain boundaries in nanocrystalline Pd has been deduced from a rule-of-mixtures analysis of density and thermal expansion coefficient measurements. The atomic density is found to fluctuate along the grain-boundary core with an amplitude that could be r…
Preferred equilibrium structures of a smectic-A phase grown from an isotropic phase have been investigated theoretically and experimentally. The surface-integral equation reported in our recent paper [H. Naito, M. Okuda, and Z. Ou-Yang, Phys. Rev. Lett. 70, 2912 (1993)] and a surface-differential equation are derived…
The gene encoding the F420-dependent N5,N10-methylenetetrahydromethanopterin reductase (Mer), which catalyzes an intermediate step in methanogensis, was cloned and sequenced from the thermophilic Methanobacterium thermoautotrophicum strain Marburg. The gene was identified on a 3.8-kbp BamHI fragment of M. thermoautotr…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermal Decomposition of Energetic Materials. 68. Decomposition and Sublimation Kinetics of NTO and Evaluation of Prior Kinetic DataG. K. Williams and T. B. BrillCite this: J. Phys. Chem. 1995, 99, 33, 12536–12539Publication Date (Print):August 1, 1995Publication History Pub…