Materials Literature
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The spatial arrangements of sodium cations for a series of sodium phosphate glasses, x Na 2 O·(100- x )P 2 O 5 ( x ≤ 55), were investigated using 23 Na spin−echo NMR spectroscopy. The spin−echo decay rate is a function of the Na−Na homonuclear dipolar coupling, and is related to the spatial proximity of neighboring Na…
The most frequently observed focal conic domains (FCD's) in lamellar phases are those based on confocal paris of ellipse and hyperbola. Experimentally, the eccentricity of the ellipse takes a broad range of values 0</=e<1. We present an analytical expression for the curvature energy of a FCD that is valid in the entir…
We report an abnormal room-temperature magnetoresistance behavior in self-doped ${\mathrm{Ag}}_{2+\ensuremath{\delta}}\mathrm{Te}$ films with Ag doping concentration $\ensuremath{\delta}<~0.25.$ Both positive magnetoresistance and negative magnetoresistance are found with the magnetic field applied along perpendicu…
PURPOSE: To study the biocompatibility of a bovine type I collagen preparation as a material for small-vessel stent-grafts in rabbits. MATERIALS AND METHODS: A composite nitinol-collagen endovascular stent-graft with a 4-mm inner diameter was deployed in the abdominal aorta in nine rabbits. Angiography was performed,…
8 3 , = 4, p m = 5.698 g -cm" 3 , Rgt(F) = 0.089, wR(F) = 0.086, =293 .
Liquid crystalline polymer–poly(butylene terephthalate) (LCP/PBT) blends were prepared by melt mixing. The LCP employed was a thermotropic copolyesteramide based on 30 mol % of p-amino benzoic acid (ABA) and 70 mol % of poly(ethylene terephthalate) (PET). The thermal, dynamic mechanical and rheological properties, mor…
Inspired from an experimentally examined organic conductor, a mechanism for negative magnetoresistance is proposed for repulsively interacting electrons on a lattice whose band dispersion contains a flat portion (a flat bottom below a dispersive part here). When the Fermi level lies in the flat part, the electron corr…
An analysis is made of the behavior of optical spectra of lead-silicate glasses, with variable lead content near the UV absorption edge, and within the 80–470-K range. A generalized formulation of the modified Urbach rule, applicable to glassy materials within a broad temperature range, is proposed for the interpretat…
Molecular-dynamics simulations of the glass former ${\mathrm{Ca}}_{0.4}{\mathrm{K}}_{0.6}{(\mathrm{N}\mathrm{O}}_{3}{)}_{1.4}$ (CKN) have been performed with a polarizable model for the nitrate ion. Polarization effects in the anion were included with a fluctuating charge model. Comparison of the Ca-Ca partial radial…
Fourier transform (FT)-Raman spectroscopy and FT surface-enhanced Raman spectroscopy (FT-SERS) are applied for the first time to study the chemical oxidative changes undergone by caffeic acid (CA) in solution and when adsorbed on silver colloids. UV-visible spectroscopy was also applied to follow the polymerization of…
Wittite and cannizzarite, two rare and structurally related nonstoichiometric sulfosalts belonging to the system Pb‐Bi‐S‐Se, were found together around high-temperature fumaroles at La Fossa crater, Vulcano island, Italy. This occurrence makes a comparative study by different methods possible (scanning electron micros…
In previous kinetic studies of Escherichia coli aspartate aminotransferase, it was determined that some substitutions of conserved cysteine 191, which is located outside of the active site, altered the kinetic parameters of the enzyme (Gloss,L.M., Spencer,D. E. and Kirsch,J.F., 1996, Protein Struct. Funct. Genet., 24,…
Esters of cellulose with trifluoroethoxy acetic acid (TFAA) were prepared in homogeneous phase using a mixed anhydride with p-toluenesulfonic acid. Esters with low degree of substitution (DS), and with DS rising from 0 to 3, had hydrophobic character that prevented the usual association with moisture, which is otherwi…
Photopyroelectric measurements of the anisotropy in the thermal conductivity Deltak vs temperature in the nCB (n=5,ellipsis,9) series are reported. The data have been used to deduce the behavior of the orientational order parameter Q close to the nematic-isotropic (N-I) and smectic A-nematic (A-N) phase transitions, r…
Dose dependent structural modifications in Si(100) due to 1.5 MeV implantation of Sb have been characterized using Raman spectroscopy and Rutherford backscattering spectrometry/channeling (RBS/C) techniques. With increasing fluence, an intensity reduction of the first order Raman peak, characteristic of crystalline Si…
Methods for synthesizing bistolane liquid crystal materials with lateral methyl and ethyl substituents are presented. Some of the bistolanes are nematic at room temperature. These highly conjugated mesogens exhibit wide nematic ranges, small enthalpies of fusion, high birefringence and modest viscosity. Their potentia…
The single‐edge V‐notched‐beam fracture testing method was used to measure the short‐crack R ‐curve behavior of a 90‐vol%‐alumina–10‐vol%‐ceria‐doped zirconia multilayered composite. The initiation and extension of short cracks from the V‐notch tip were observed in situ via optical microscopy. Initial crack lengths of…
Seven homologous imidazoline type inhibitors were synthesised, all being derivatives of cyclopentyl- and cyclohexylnaphthenic acids. The protective effectiveness of these compounds was investigated by applying the potential sweep method to the carbon steel St3S and austenitic steel 1H18N9T in a 2% solution of sodium c…
The density of states is studied for periodic and open boundary conditions in the vertex model of the Penrose tiling. For one gap in the spectrum the gap labeling is done explicitly. Localization of wave functions is studied by $2p$ norms in a series of approximants for one value of the energy by means of a contour in…
The magnetostriction measurements of almost stoichiometric single crystalline Ni _2 MnGa compound with T_m<T_C ( T_m and T_C are the martensitic and ferromagnetic transformation temperatures respectively) at constant temperatures have been performed in a temperature range of 100--400 K. The measurements resulted in…