Materials Literature
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Abstract Four new epoxy monomers have been synthesized and characterized as part of a program to prepare novel liquid crystal thermoset (LCT) materials. Three of the new epoxy monomers contained a biphenyl mesogen and were not liquid crystalline (LC). The remaining epoxy monomer, which contained a 1,4‐dibenzoyloxybenz…
Samples of liquid crystalline poly(γ-benzyl-glutamate) solutions are sheared between glass surfaces with gaps, d = 10–500 μ, and shearing velocities, V = 0·05–10 000 μs−1 so that the Ericksen number E [tbnd] Vdγ 1/K is varied over a large range, E ≈ 1–107. Here γ1 is the rotational viscosity and K 1 is the Frank splay…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEnd-functionalized polymers. 1. Synthesis and characterization of perfluoroalkyl-terminated polymers via chlorosilane derivativesM. O. Hunt Jr., A. M. Belu, R. W. Linton, and J. M. DeSimoneCite this: Macromolecules 1993, 26, 18, 4854–4859Publication Date (Print):August 1, 19…
ADVERTISEMENT RETURN TO ISSUEArticleNEXTFormation of hydronium at the Broensted site in SAPO-34 catalystsLeonardo Marchese, Jiesheng Chen, Paul A. Wright, and John Meurig ThomasCite this: J. Phys. Chem. 1993, 97, 31, 8109–8112Publication Date (Print):August 1, 1993Publication History Published online1 May 2002Publishe…
The dilute-limit heats of solution for all binary alloys of six bcc transition metals (V, Nb, Ta, Mo, W, and Fe) have been calculated with the analytic embedded-atom model for bcc pure metals by Johnson and Oh. Cubic equations are proposed and used for providing a smooth cutoff for the calculated potential and electro…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew antiferromagnetic dinuclear complexes of nickel(II) with two azides as bridging ligands. Magneto-structural correlationsJoan Ribas, Montserrat Monfort, Carmen Diaz, Carles Bastos, and Xavier SolansCite this: Inorg. Chem. 1993, 32, 16, 3557–3561Publication Date (Print):Au…
To investigate the effects of oxygen codoping on Er luminescence centers in GaAs, we grew Er-doped GaAs by low-pressure metalorganic chemical vapor deposition (MOCVD) and measured the photoluminescence spectrum due to the intra-4f-shell transition of Er. The spectrum of a sample grown in a pure hydrogen atmosphere was…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTwo new .mu.-azido nickel(II) uniform chains: syntheses, structures, and magneto-structural correlationsAlbert Escuer, Ramon Vicente, Joan Ribas, M. Salah El Fallah, Xavier Solans, and M. Font-BardiaCite this: Inorg. Chem. 1993, 32, 17, 3727–3732Publication Date (Print):Augu…
Transition-state theory was employed to study the dynamics of light gases dissolved in rigid microstructures of glassy polycarbonate and rubbery polyisobutylene modeled in atomistic detail. The gaseous molecules migrated through the polymer structures in a sequence of ‘‘hops’’ between local minima of the potential ene…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInvestigation of intermediate steps in the self-assembly of n-alkanethiols on gold surfaces by soft x-ray spectroscopyG. Haehner, C. Woell, M. Buck, and M. GrunzeCite this: Langmuir 1993, 9, 8, 1955–1958Publication Date (Print):August 1, 1993Publication History Published onl…
The quasiperiodic structure of decagonal Al 70 Ni 15 Co 15 was determined on the basis of X-ray single-crystal intensity data using the n-dimensional embeding method. Centrosymmetric five-dimensional space group P10 5 /mmc, three-dimensional reciprocal and direct quasilattice parameters: a i * =0.2636 (1) A -1 , i=1,.…
First- and third-order dynamic polarizabilities and hyperpolarizabilities of aza-cyanine and symmetric cyanine dyes have been computed exactly within the correlated Pariser–Parr–Pople model defined over the π framework. The exact nonlinearities of the model have been compared with those of polyenic systems. It is foun…
TiO 2 thin films were grown on sapphire substrates at 500°C by means of reactive ionized cluster beam (RICB) deposition. The TiO 2 thin films grown on sapphire (0001) and (112̄0) substrates were single-crystalline and had the rutile structure. The epitaxial orientation relationships between the rutile films and the sa…
A self-tuned magnetostrictive/piezoelectric hybrid Tonpilz transducer which produces enhanced motion at one end and canceled motion at the other is presented. The particular hybrid Tonpilz transducer described here consists of two 5.4 in. (13.65 cm) diameter circular pistons with a central mass separating a Terfenol-D…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotoresponsive coordination of stilbazoles to metalloporphyrinsYuki Iseki, Eishun Watanabe, Atsunori Mori, and Shohei InoueCite this: J. Am. Chem. Soc. 1993, 115, 16, 7313–7317Publication Date (Print):August 1, 1993Publication History Published online1 May 2002Published ini…
Abstract In concentrated alkaline sodium silicate solutions a consistent decrease in the amount of silicate monomer Q 0 , end‐groups Q 1 , cyclic trimer Q groups and middle groups Q 2 , and also branching groups in ring formations Q , is observed with increasing molar ratio of SiO 2 to Na 2 O ( R M), whereas for branc…
A review is given on the determination of the thermodynamic properties of Si(OC2H5)4 (TEOS, tetraethoxysilane). In addition, the thermal decomposition of TEOS has been studied by in-situ IR spectroscopy. The decomposition products in the gas phase in the absence of oxygen are organic fragments (ethanol, ethanal, ethen…
Porphyrins are the molecules which are at the heart of most biochemical reactions involved in bioremediation. This review paper discusses the chemical structures, the biosynthetic pathways and the occurrence of porphyrins in the environment. The parallel between the mammalian and bacterial cytochrome P-450 enzyme syst…
Abstract The “Formation Rouge” from the Jbel Rhassoul in Morocco is composed of detrital sediments which have a lacustrine origin. The clays contained in the less than 2 µm fraction of the sediments are detrital phengites and illites, illite/smectites or smectites, and palygorskite. Due to the presence of well preserv…
We have investigated the different contributions to the entropy change at the martensitic transition of different families of Cu-based shape-memory alloys. The total entropy change has been obtained through calorimetric measurements. By measuring the evolution of the magnetic susceptibility with temperature, the entro…