Materials Literature
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Abstract The interfacial structure and diffusion kinetics of two compatible polymers, poly(methyl methacrylate) and poly(vinylidene fluoride) are studied in the melt. The interdiffusion rates of the two components are found to be unequal, giving unequal diffusion coefficients, a net mass flow across the interface, and…
We describe a new approach to probe the molecular biology of the living cell that uses small colloidal gold particles coupled to specific ligands. They are visualized in cells by bright-field, video enhanced contrast microscopy. We describe the basic aspects of the technique and provide examples of applications to int…
The kinetics and energetics of chromium-sensitized neodymium luminescence of several codoped gallium garnets (YAG, YSGG, GGG, and GSGG) have been measured and interpreted in terms of microscopic physical-energy-transfer mechanisms. Sensitized luminescence in YAG and in YSGG is well described by the static energy-trans…
Controlled potential electrolysis of the dilithium salt of phthalocyanine, Li2(pc2–), at 0.15 V vs. saturated calomel electrode in acetonitrile gave a lithium complex of the phthalocyanine radical, the crystal structure of which shows that it contains a unit cell with four nearly planar Li(pc˙–) molecules of S4 symmet…
High conversions of alkanes into alcohols and ketones were obtained by using H2O2 as an oxidizing agent and a Mn-prophyrin as the catalyst in the presence of imidazole; yields between 40 and 85% for oxidation of cyclohexane, cyclo-octane, adamantane, and various compounds containing a benzylic C-H bond by diluted aque…
A copper phthalocyanine with four crown ether voids has been synthesized; its high tendency towards aggregation, especially K+-induced aggregation, which enables the phthalocyanine to be used as a colorimetric reagent, is reported.
The cholesteric liquid crystalline phases of three polymers of biological interest have been investigated: PBLG (a polypeptide), DNA (a polynucleotide) and xanthan (a polysaccharide). The textures (and the defects which they contain) of these three mesophases are analysed and compared The main difference concerns foca…
The oxidation of pyrrole to conducting polypyrrole by iron(III) salts represents a valid and more versatile alternative to the usual anodic oxidation.
Variable-temperature powder X-ray diffractometry, Fourier-transform infrared spectroscopy and 27Al and 29Si magic-angle spinning nuclear magnetic resonance spectroscopy have been used to elucidate both the nature of alumina pillars introduced into sheet aluminosilicate and to monitor changes in structure of the host m…
The phase diagram of the two-dimensional classical Coulomb gas is investigated by Monte Carlo simulations. We show that in the fluid phase this system undergoes the expected Kosterlitz-Thouless transition at very low densities and that the Kosterlitz-Thouless transition becomes a first-order phase transition between a…
Amphiphilic molecules are well-known for their ability to build symmetric fluid films, or bilayers, most often organized in lamellar phases. The symmetric changes of curvatures of the two interfaces of a bilayer, as temperature and water content vary, may enter into conflict with the compactness of the bilayer core. W…
For the first time, in the SDW state of the organic conductors (TMTSF) 2PF 6 and (TMTSF)2ClO4, the nesting vector Q is determined from a detailed analysis of the methyl proton N.M.R. lineshape for various magnetic field orientations. The amplitude δ of the order parameter is determined with a precision superior to tha…
Abstract An improved correction model for quantitative electron probe microanalysis, based on modifications of the Gaussian ϕ(ϱ) approach, originally introduced by Packwood and Brown , is presented. The improvements consist of better equations for the input parameters of this model which have been obtained by fitting…
The polarized infrared (400-4 000 cm-1) absorption spectra of single crystals of the α form of (BEDT-TTF)2I3 are reported for the high temperature conducting phase at T = 300 K and for the low temperature semiconducting one at T = 20 K. For comparison and to supplement the already available data, the conductivity spec…
The way in which surface tension acts as a singular perturbation to destroy the continuous family of needle-crystal solutions of the steady-state growth equations is analyzed in detail for two local models of solidification. All calculations are performed in the limit of small surface tension or, equivalently, small v…
This report contains papers on research with boron-rich solids. These papers main describe the following topics: electronic structure; electronic and optical properties; superconductivity; crystal structure; magnetic properties; vibrational properties; thermal and elastic properties; phase diagrams; materials; prepara…
Abstract The X-ray crystal structure analysis of a sulfur containing π-donor molecule, bis(ethylenedithio)tetrathiafulvalene, (BEDT-TTF) shows that the BEDT-TTF molecule is nonplanar and that the crystal is composed of pairs of BEDT-TTF.
Abstract Low-energy electron diffraction (LEED) is a technique for investigating the crystallography of surfaces and overlayers adsorbed on surfaces. This article describes the principles of diffraction from surfaces, and elucidates the method of sample preparation to achieve diffraction patterns. The article describe…
Introduction Basis of Mass Balance Method Calculation of Removals External Sources Data from Examination of Oxide Layers on Primary Circuit Components Completion of Mass Balances by Predicting Nett Releases from Circuit Alloys Estimation of Nett Corrosion Releases from Chromium Enrichment Preliminary Discussion of Cob…
Neutron powder diffraction data of cubic CsNO 2 at room temperature (space group Pm 3 m , a = 4.389 Å) are analyzed with several models for the orientationally disordered NO 2 group. The density distribution of O and N atoms are expanded on spherical shells with cubic harmonics. The density of the O atoms is concentra…