Materials Literature
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Strong pulsed electron emission has been observed from 12/65/35 lead lanthanum zirconate titanate ceramic composition in two different nonswitched phases at room temperature and at the temperature 100 °C. The electron emission parameters of this composition appear to be independent of phase for the two phases investig…
Abstract In‐situ FTIR studies on the conformational changes of poly(ethylene terephthalate) (PET) films with different thermal histories, i. e., quenched from the melt and sub‐ T g annealed at different temperatures, were carried out while increasing the temperature through the glass transition region. The temperature…
We present a theoretical approach for studying the deformation of grafted polymer layers in strong shear flows that calculates the deformation of grafted chains and the solvent flow profile within the layer in a mutually consistent fashion. We illustrate this approach by considering the deformation of Alexander-de Gen…
Experiments were performed on the motion of isolated drops and bubbles in a Dow-Corning silicone oil under the action of an applied temperature gradient in a reduced gravity environment aboard the NASA Space Shuttle in orbit. Images of the interior of the test cell during these experiments were recorded on cine film a…
A systematic study of the effects of poling time and applied voltage on second-harmonic (SH) generation in thermally poled silica glass reveals that the SH signal is proportional to the square of the applied voltage and that the speed of the poling process increases with the applied voltage. Prior treatment of the sam…
Abstract TEM characterization of stacking relations in I/S of expanded shale samples from the Gulf Coast and Michigan Basin was carried out to address the issues of the degree of coherency and the nature of layer stacking sequences in smectite, I/S and illite. The two-dimensional lattice fringe images obtained from th…
Abstract The weathering of chlorite, one of the major minerals of the host rock in the uranium ore deposit at Koongarra, Australia, was examined by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), electron microprobe analysis, and transmission electron microscopy (TEM). The conversion sequence of…
The energy density crystallization threshold of amorphous GeSb films has been studied for the first time as a function of the laser pulse duration in the range from 170 fs to 8 ns. The results obtained provide evidence of the existence of enhanced crystallization upon irradiation with pulses shorter than 800 fs, which…
Theoretical and practical information on galvanic corrosion of zinc and its alloys, coupled to other metals, particularly steel, is organized and presented, along with a conceptual and elemental analysis of galvanic coupling between zinc and steel. Various factors which may play roles in galvanic action between zinc a…
An NAD(P)-glucose dehydrogenase from the extremely halophilic Archaeon, Haloferax mediterranei, has been purified to electrophoretic homogeneity. The purified enzyme has been characterised with respect to its cofactor specificity, subunit composition and its salt and thermal stability. The N-terminal amino acid sequen…
Abstract Toluene‐ d 8 solutions of methylaluminoxane (MAO) after the addition of different amounts of trimethylaluminium (TMA) have been studied by means of 1 H and 13 C NMR at a temperature as low as −78°C to freeze out some of the fluxional equilibria of the molecule. A comparison of the half height width of the NMR…
A microrheological model for the consolidation of aggregated colloidal dispersion is presented. Interparticle forces are responsible for the formation of the fractal-like network of particles chains. Aggregation is supposed to be weak in that the chains are gradually created and annihilated. In the framework of this m…
A surface model was developed for diamondlike-carbon film deposition, and was connected in a self-consistent way with a one-dimensional plasma chemistry and physics model for a CH4 radio-frequency (rf) discharge. The surface model considers the adsorption of multiple species (CH3, CH2, and H), and solves for the surfa…
The existence of an orientationally disordered cubic phase of solid ethanol is revealed by x-ray diffraction and Raman spectroscopic measurements. Such a phase, whose existence was postulated some time ago on the basis of specific-heat measurements, is produced by quenching below some 95 K a plastic crystal formed upo…
Vascular grafts, devices designed to augment inefficiently functioning vascular systems, represent a significant part of implantable medical devices, with major participation in over a million vascular surgeries performed worldwide. By definition accepted in the art, a small caliber graft is a conduit with internal di…
Oxygen self-diffusion coefficients were determined in polycrystals of α-alumina either ‘undoped’ or doped with 500wt.ppm (225molppm) Y2O3 in the temperature range 1460-1720°C, with 18O2 and secondary-ion mass spectrometry. Oxygen grain-boundary diffusion coefficients obey the relations for ‘undoped’ alumina and for ‘y…
To determine when secondary structure forms as two chains coalesce to form an alpha-helical dimer, the folding rates of variants of the coiled coil region of GCN4 were compared. Residues at non-perturbing positions along the exterior length of the helices were substituted one at a time with alanine and glycine to vary…
We propose, based on recent experimental results, a polyyne ring nucleus (PRN) growth model for the synthesis of single-layer nanotubes (SLN's). The PRN model assumes that (i) the critical nuclei are the planar carbon polyyne rings that are observed to be most stable for sizes in the range ${\mathrm{C}}_{10}$ to ${\ma…
The molecular anchoring and orientational wetting properties of a liquid crystal close to the nematic-isotropic transition temperature confined to the 0.2 \ensuremath{\mu}m cylindrical channels of alumina membranes are investigated for various surface preparations. The cavity walls of the confining pores are chemicall…
The dc resistivity, magnetoresistance, and magnetic susceptibility of ${\mathrm{La}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{CoO}}_{3}$ compounds have been investigated in the temperature range of 4--300 K for magnetic fields up to 7 T. In the doping range studied (0.05\ensuremath{\l…