Materials Literature
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In recent years due to improvements in calculation methods and increased computer power, it has become possible to perform first-principles investigations for ``simple'' chemical reactions at surfaces. We have carried out such studies for the catalytic oxidation of CO at transition metal surfaces, in particular, at th…
In a nearly half-metallic ferromagnet, such as a material exhibiting ``colossal'' magnetoresistance, the minority spin electrons close to the band edge at the Fermi energy are Anderson localized due to disorder; thus only majority electrons conduct current. This presents a unique electronic structure for which the lin…
Crystalline, size-selected Si nanocrystals in the size range 1.8–10 nm grown in inverse micellar cages exhibit highly structured optical absorption and photoluminescence (PL) across the visible range of the spectrum. The most intense PL for the smallest nanocrystals produced (∼2 nm) was in the blue (∼365 nm) with a ra…
We report tunnel magnetoresistance (TMR) measurements on $\mathrm{Co}/{\mathrm{SrTiO}}_{3}/{\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}$ junctions. The half-metallic ${\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}$ electrode is used as a spin analyzer. The large $(\ensuremath{-}50%)$ inverse TMR…
The recently completed Department of Energy (DOE) and industry sponsored Cooperative Research and Development Agreement (CRADA) entitled, ''Electron Beam Curing of Polymer Matrix Composites,'' determined that the interlaminar shear strength properties of the best electron beam cured IM7/epoxy composites were 19-28% lo…
In this work, blends of poly(butylene terephthalate) (PBT) and linear low-density polyethylene (LLDPE) were prepared. LLDPE was used as an impact modifier. Since the system was found to be incompatible, compatibilization was sought for by the addition of the following two types of functionalized polyethylene: ethylene…
Benzoic and stearic acids are shown to react with 2- bisbenzothiazole-2,2′-disulfide (MBTS) and its polysulfides (MBTP) at vulcanization temperatures to form acid-accelerator complexes 2-benzoylthiobenzothiazole (BzM) and stearicthiobenzothiazole (StM), respectively. At higher temperatures MBTS, MBTP, BzM, and StM are…
A new synthesis of a phosphazene-based polymer precursor is described. tert-Butylhydroquinone was found to react with hexachlorocyclotriphosphazene in the presence of a base, 4-picoline, in cyclohexane to yield a regiospecifically substituted hexa-tert-butylcyclotriphosphazene. This reaction proceeds more rapidly to c…
Polyaniline is prepared by chemical polymerization of aniline in an acidic solution using H2O2 as an oxidant and ferrous chloride as a catalyst. A wide variety of synthesis parameters are studied, such as the amount of the catalyst, reaction temperature, reaction time, initial molar ratio of oxidant, monomer and catal…
The ordered [head-to-head (H−H) or tail-to-tail (T−T)] poly(amide−ester) was prepared by polycondensation of a symmetric monomer, isophthaloyl chloride (1), with 4-(2-aminoethyl)phenol (2) as a nonsymmetric monomer. The polymerization was conducted in NMP in the presence of triethylamine (TEA) at −20 °C by slow additi…
The magnetic properties of a series of Fe x Cd 1 - x PS 3 layered compounds ( x = 0.1−0.8) and of their methyl viologen intercalates have been studied. The results imply that the Fe 2+ ions are not randomly dispersed on the metallic sites, as they retain strong in-plane magnetic interactions even at high dilution. The…
Diblock copolymers in the melt exhibit order–disorder phase transitions (ODT), which are accompanied by strong concentration fluctuations. These transitions are generally described in terms of the random phase approximation (RPA) of Leibler and Fredrickson, which is able to explain small angle scattering results in th…
The phase behavior and linear viscoelasticity of a mixture of a matched diblock and triblock copolymer of styrene and ethylene−butene-1 are reported. The mixture undergoes reversible thermotropic transitions from a cylindrically ordered state at low temperatures to a spherically ordered state at intermediate temperatu…
We contrast the adsorption of human serum albumin (HSA) onto two solid substrates previously primed with the same polyelectrolyte of net opposite charge to form one of two alternative structures: randomly adsorbed polymer and the “brush” configuration. These structures were formed either by the adsorption of quaterniz…
The conformation of various polystyrene chains with first (G-1), second (G-2), and third generation (G-3) Fréchet-type dendrons at the repeat unit has been investigated with small-angle neutron scattering. The increased density of the attached dendrons leads to a systematically greater cross-sectional chain diameter D…
Characterizing the inherent flexibility of a protein provides an important link between structure and function. In this article, we examine some of the methods used to determine protein flexibility, and address several unanswered questions relating to them. We perform 4 ns simulations of bovine pancreatic trypsin inhi…
Deuterium nuclear magnetic resonance (NMR) powder spectra and spin-lattice relaxation times (T(1)) are used to measure the deuterium quadrupolar coupling constants (QCCs) chi(BD) and chi(ND) and to investigate the molecular reorientation of the BD(3) and ND(3) groups in solid deuterated borane monoammoniate, BD(3)NH(3…
The reactions of sodium sulfide or disulfide with sulfur, when heated, are examined through Raman spectroscopy. It is shown that whatever the composition of the mixtures, the solid sodium sulfide or disulfide transforms into the crystalline alpha-Na(2)S(4) phase in a first step, with alpha- or beta-Na(2)S(2) as an int…
We have identified a channel of bicontinuous microemulsion in three chemically distinct hompolymer/hompolymer/block copolymer (A/B/A−B) ternary bends. Experiments were conducted along the isopleth, defined by equal volumes of homopolymer and varying amounts of block copolymer, as a function of temperature. A symmetric…
The crystal structure and a phase transition of gadolinium orthoborate, GdBO 3, were studied by electron diffraction and X-ray powder diffraction. GdBO 3 crystallizes in the vaterite structure (LT), in a rhombohedral space group R 32 with the lattice constants of a = 6.6357(2) Å and c = 26.706(1) Å. The structure of t…