Materials Literature
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A model for subcritical parity-breaking bifurcation of a periodic pattern is introduced. It is found that nucleated regions of the new asymmetric state propagate with a well-defined velocity in a direction determined by their parity, and leave in their wake a pattern with an altered wavelength. Successive passage of t…
We report a study of a fingering instability which occurs during the spreading of a spinning drop. We measure the time evolution of the drop profile, the critical radius for instability onset, and the fastest growing instability wavelength. The experimental results are compatible with the predictions of lubrication th…
We report a Hall effect and magnetoresistance study of sin- gle crystals of the organic superconductor tetramethyl-tetraselenafulvalinium hexafluorophosphate, (TMTSF${)}_{2}$${\mathrm{PF}}_{6}$, under hydrostatic pressure at temperatures down to 0.5 K in magnetic fields up to 25 T. There is clear evidence for a quanti…
An atomic model of 43,692 non-hydrogen atoms has been determined for the 12-subunit enzyme glutamine synthetase from Salmonella typhimurium, by methods of x-ray diffraction including restrained least-squares atomic refinement against 65,223 unique reflections. At 3.5 A resolution the crystallographic R-factor (on 2 si…
The temperature dependence of the electrical properties of the semiconducting amorphous copper-tellurite glasses is presented in a range of compositions. A polaronic model is shown to be generally applicable, and the variation of activation energy with the glass composition is found to dominate the conductivity. In pa…
Ultraviolet photoelectron spectroscopy (UPS) has been used to observe changes in the \ensuremath{\pi}-band structure in poly(3-hexylthiphene) induced by doping using ${\mathrm{NOPF}}_{6}$. The charge-induced movement of the Fermi energy and a finite density of electronic states at the Fermi energy in the most highly d…
A new diluted magnetic III-V semiconductor of ${\mathrm{In}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$As (x\ensuremath{\le}0.18) has been produced by molecular-beam epitaxy. Films grown at 300 \ifmmode^\circ\else\textdegree\fi{}C are predominantly ferromagnetic and their properties suggest the…
Abstract The reaction of α,ω‐bis(dimethylamino) polytetramethylene oxide with various dihalides provided a series of elastomeric ionenes. The influence of dihalide structure on the reaction was studied and a number of substituents were found which dramatically increased the rate of polymerization and ultimate molecula…
We compute the shear viscosity of three dimensional simple fluids using nonequilibrium molecular dynamics. We show that for systems of 256 particles or more, the shear viscosity is, within ½ per cent, independent of the number of particles used in the simulation. We estimate that the zero shear rate viscosity of the t…
Abstract Studies have been made on the melt rheological properties of poly(vinyl chloride) (PVC) with copolymers of methyl methacrylate (MMA) and methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BA), and 2‐ethyl hexyl acrylate (EHA) at a blending ratio of 80:20. Effect of blend composition on shear stress–sh…
Abstract A series of segmented ionene polymers based on the reaction of α,ω‐bis(dimethyl amino)polytetramethylene oxide with various dihalide compounds were investigated with respect to their structure–property behavior. The placement of quaternary ammonium ions and halide counterions along the polymer chains was vari…
Abstract The alkali hydrolysis of poly(ethylene terephthalate), anionic copolymer of poly(ethylene terephthalate), and block copolymer of poly(ethylene terephthalate)–poly(ethylene glycol) is investigated under a variety of conditions of alkali concentration in aqueous bath, additives, time, and temperature. Measureme…
Abstract X‐ray diffraction and microscopical investigation of test samples prepared by injection molding from composites of isotactic polypropylene with talc revealed a preferred orientation of the talc and polypropylene matrix. Contrary to the situation in polypropylene alone, the preferred orientation in polypropyle…
Preparations of recombinant bovine calbindin D9k (r-calbindin) that appear homogeneous on SDS electrophoresis gels have been shown by isoelectric focusing to be mixtures of proteins differing in net charge. The production of two isoforms with increased negative charge occurs during a routine urea denaturation step and…
Stoichiometric and amorphous thin layers of In2Te3 are obtained by vacuum thermal evaporation on glass substrates preheated at 300 °C. Annealing under nitrogen atmosphere modify the film structure. The best annealing conditions are determined to obtain polycrystalline films of In2Te3 with preferential orientation [111…
Electron diffraction and microscopy observations reveal that the sequence of the phase transformations of Cu2−xTe (x < 0.05) is a typical case of a normal-incommensurate–commensurate phase transition, with the incommensurate phase splitted into two phases; one of these, the γ-phase, is modulated by regularly spaced di…
Grain boundary precipitations of the B93 alloy (Al + 7% Zn + 1.9% Mg + 1% Cu + 0.3% Fe) are studied in the as-annealed state and after 2% pre-straining at room temperature, the alloy being characterized by equilibrium and non-equilibrium boundaries. A considerable enhancement of grain boundary precipitates associated…
A high-speed optically addressed spatial light modulator is described which uses the electroclinic effect in chiral smectic A liquid crystals with a p-i-n photodiode of hydrogenated amorphous silicon (a-Si:H). The near microsecond response time is a function of the liquid-crystal mixture and temperature. We present an…
The formation of a plastic zone, in the form of a linear array of inclined edge dislocations in front of a mode-I crack in plane strain, is studied. The direction of the force field on an edge dislocation due to the crack load allows for the determination of the plastic zone as a function of the inclination angle. The…
Silicon nitride films were synthesized in a Balzers BAP 800 coating plant by low voltage reactive ion plating. Transparent, stoichiometric films free of hydrogen, oxygen, argon, and heavy metals were obtained. The properties of the silicon nitride films were investigated in terms of optical constants, chemical composi…