Materials Literature
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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…
We report the observation of electrically induced changes in transmissivity in Fabry-Perot devices consisting of spin-cast azo-dye/polymer films deposited between gold mirrors. In poled samples the observed modulation shows a linear dependence on the applied modulating voltage. The ratio of the transmissivity modulati…
The adsorption, thermoreactions, and photoreactions of NO coadsorbed with potassium on Si(111)7×7 at 90 K have been investigated using work-function measurements, high-resolution electron energy loss spectroscopy, and mass spectrometry. A minimum in the work function of Si(111)7×7 at 90 K vs the potassium exposure is…
Using the energy transfer parameters deduced from the study on nonexponential luminescence decay of the 4F3/2 level of Nd3+ in YAG at room temperature, it is shown that up to 1.5 at. % Nd, the relative quantum efficiency is reduced by an amount of 18.2C, C being the relative (to Y3+) Nd concentration. It is pointed ou…
Heat capacity measurements of four lanthanide sesquisulfides La2S3, Ce2S3, Nd2S3, and Gd2S3, prepared in the γ phase, have been obtained between 6 and 350 K by adiabatic calorimetry. The total heat capacity has been resolved into lattice, electronic, magnetic, and Schottky components. The Schottky contributions agree…
A new type of superlattice, a Fibonacci acoustic superlattice, is presented. Its ultrasonic spectrum, which is excited by the piezoelectric effect, has been studied theoretically and experimentally. The results are in good agreement with each other.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotoreduction fluorescence detection of quinones in high-performance liquid chromatographyJames R. Poulsen and John W. BirksCite this: Anal. Chem. 1989, 61, 20, 2267–2276Publication Date (Print):October 15, 1989Publication History Published online1 May 2002Published inissue…
We present an ab initio calculation of polarizability and second hyperpolarizability for the benzene molecule including electron–electron correlation. The finite field method is used. For each selected strength of the applied electric field the energy of the benzene molecule is calculated using the self-consistent fie…