Materials Literature
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A theoretical model is established to predict stress-strain and torque-tensile strain curves of a yarn. The yarn is described by its properties and the arrangement of its fibers, which have a finite length. The yarn is transformed into finite elements. Equilibrium is expressed by virtual work, and is calculated iterat…
The generalized Landau--de Gennes theory for uniaxial and biaxial nematic liquid crystals is analyzed using tensor analysis. In this way all terms allowed by symmetry appear in the free-energy expression. This improves the quantitative shortcomings of the commonly used theory. It appears that uniaxial nematic liquid c…
The evolution of a copper precipitate with a diameter of 3·5 nm containing up to 2·0 at.% of vacancies at different temperatures has been studied by molecular dynamics. The diffusion coefficients were calculated for a single vacancy and vacancy concentrations inside the precipitate of 0·5, 1·0 and 2·0 at.%. The diffus…
The magnetic behavior of some ${\mathrm{R}}_{2}$${\mathrm{Fe}}_{17}$ single crystals have been analyzed quantitatively in a wide temperature range, using a two-sublattice approximation for the magnetic structure and taking into account isotropic exchange and single-ion crystal-field interactions. The 3d sublattice beh…
We prepared thin WN x films with various compositions by reactive sputtering and examined their characterizations and barrier properties applied to Cu/WN x /Si contact systems. The results indicate that the W 65 N 35 barrier, which is in the W 2 N phase with preferred orientation in the (111) plane, shows excellent ba…
Sulfolobus sulfataricus ATCC 35091, Haloferax volcanii, and Methanosarcina thermophila TM-1, representing the Euryarchaeota and Crenarchaeota subdomains of the Archaea, contain proteins which are phosphorylated on tyrosine. These data raise fundamental questions as to the origin and evolution of tyrosine phosphorylati…
Thin films of five different spinels MgAl2O4, MgCr2O4, MgIn2O4, TiMg2O4 and MgFe2O4 were grown by topotaxial solid state reactions on MgO(001) substrates. The spinels widely differed in their lattice parameter resulting in a variation in sign and amount of lattice misfit to the substrate. The films were characterized…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTSynthesis of Aromatic Polyisophthalamides by in Situ Silylation of Aromatic Diamines†Angel E. Lozano, Javier de Abajo, and José G. de la CampaView Author Information Instituto de Ciencia y Tecnología de Polímeros, C.S.I.C. Juan de la Cierva 3, 28006 Madrid, SpainCite this: Macr…
The angular properties of various wideband high reflectors are investigated. The theory is developed for the design of high reflectors based on contiguous quarter-wave stacks for use at one oblique angle or for a range of angles of incidence. Numerical results are presented for several high reflectors designed to have…
, Ute Schlue, Maria Koczor, Julie A. Chitty, William C. Taylor, Peter Westhoff, The Promoter of the Gene Encoding the C₄ Form of Phosphoenolpyruvate Carboxylase Directs Mesophyll-Specific Expression in Transgenic C₄ Flaveria spp, The Plant Cell, Vol. 9, No. 4 (Apr., 1997), pp. 479-489
A phase transition from a high-symmetry to a low-symmetry commensurate phase through an incommensurate phase was studied in the framework of the one-dimensional elastically hinged molecule model which includes only a fourth-order anharmonic potential. The phase diagram with respect to the harmonic-potential coefficien…
The nature of the orientational, translational, and conformational disorder exhibited by poly(tetrafluoroethylene) has been characterized with the help of molecular dynamics calculations based on a new all-atom interaction potential function developed specifically for the perfluoroalkanes. The simulation has identifie…
Abstract Epoxidation of undecylenic acid and its methyl and ethyl esters with aqueous H 2 O 2 was carried out by using different traditional routes, ion exchange resin, and the newly developed synergistic usage of heteropoly acids and phase transfer catalysis in a biphasic system. The so‐called Ishii‐Venturello chemis…
The scenarios of the size effects which may account for the difference in the switching properties of ferroelectric thin films and bulk ferroelectrics are critically reviewed. It is shown that the two often used models (the Janovec-Kay-Dunn surface nucleation size effect and the dielectric layer model) are irrelevant…
The effect of rice husk ash (WRHA) as a filler in epoxidized natural rubber compounds has been studied. The mechanical properties viz tensile and tear strength were enhanced by the addition of WRHA. The optimum level of WRHA to obtain maximum mechanical properties was achieved at 20 phr after which there was deteriora…
The structure, thermal stability, and catalytic behavior of a novel highly dispersed silica-supported Pd/Sn catalyst prepared by an organometallic route have been examined by X-ray photoelectron, X-ray diffraction, and X-ray absorption, fine structure spectroscopies, the latter two measurements being carried out with…
Three kinds of 2 H-labeled Bombyx mori silk fibroin samples (with [2,2- 2 H 2 ]Gly, [3,3,3- 2 H 3 ]Ala, or [2,3,5,6- 2 H 4 ]Tyr) were obtained by oral administration of either the labeled amino acid or 2 H 2 O to 5th instar larvae. The administration of 2 H 2 O alone yielded a high degree of selective deuteration at t…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTSynthesis of Poly(tetramethyl-m-silphenylenesiloxane), an Elastomer of Enhanced High-Temperature StabilityRuzhi Zhang, Allan R. Pinhas, and James E. MarkView Author Information Department of Chemistry and the Polymer Research Center, University of Cincinnati, Cincinnati, Ohio 4…
This paper describes results of an experimental investigation into surface discharges occurring on the surface of polymeric insulators. Discharges on partially hydrophobic surfaces were found to occur across well defined dry bands, while discharges on hydrophobic surfaces appeared as small points of light occurring be…
Abstract A model for the heterogeneous oxidation of polypropylene (PP) is proposed in which it is considered that there is a small initial fraction, p o , of oxidizing centres which have a high local rate of oxidation. Within these zones there is a free radical chain reaction producing secondary oxidation products, vo…