Materials Literature
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Significant advances have been made over the past decade in using computer simulation to investigate the mechanisms associated with defect production by displacement cascades in metals. As reported at COSIRES '92 by Diaz de la Rubia et al. (Rad. Eff. and Def. Sol. 130–131 (1994) 39) and COSIRES '94 by Bacon et al. (Nu…
The leuB gene from the psychrotrophic strain Vibrio sp. I5 has been cloned and sequenced. The gene codes for 3-isopropylmalate dehydrogenase, a 360-residue, dimeric enzyme involved in the biosynthesis of leucine. Three recently solved homologous isopropylmalate dehydrogenase (IPMDH) crystal structures from thermophili…
Abstracts Systematics and description of polyions of both linked cation- and anion-centered polyhedra with face-, edge-, and corner-sharing are discussed. Some additions to the system introduced by Liebau (1985) for cation-centered polyions are proposed which take into account the property of linking. The concept of l…
The binding of three different amphiphiles (with different hydrophobic characters) to oppositely charged polyelectrolytes (κ-carrageenan, dextran sulphate, alginate, and hyaluronan) is investigated. It is shown that the degree of binding is related not only to the hydrophobicity of the amphiphile and to the charge den…
(Alkylsulfonyl)methyl-substituted poly(oxyalkylene)s were synthesized in two steps. (Alkylthio)methyl-substituted poly(oxyalkylene)s were made by the reaction of poly[oxy(chloromethyl)ethylene] (CE), poly[oxy(chloromethyl)ethylene -co- oxyethylene] (CEE), or poly[oxy-2,2-bis(chloromethyl)trimethylene] (BCT) with sodiu…
The growth of a supercritical nucleus from a diffusion field is studied numerically using a phase-field model. This represents growth of a crystal with small or vanishing anisotropy. We find three-dimensional cooperating multiplets instead of dendrites, in analogy to the doublons found previously in two dimensions. Tr…
A series of fluoro-substituted phenylthiophene monomers has been synthesized with high isolated yields (71–90%). Generalized coupling reactions have been developed for the series with a Pd(dppf)Cl2 catalyst and via Zn-complex mediated reactions. The controlled electropolymerization of monomers yielded polymeric materi…
Abstract : This report documents the numerical algorithms used in an explicit Lagrangian finite element hydrocode. One, two, and three dimensional implementations of the numerical solution of the conservation equations are covered. Triangular and tetrahedral continuum elements and shell elements are described. SPH (Sm…
The reaction of Au with a molten mixture of A 2 Q/P 2 Q 5 /Q (Q = S, Se) produced the quaternary compounds A 3 AuP 2 Se 8 (A = K, Rb, Cs) ( I − III ), A 2 Au 2 P 2 Se 6 (A = K, Rb) ( IV, V ), A 2 AuPS 4 (A = K, Rb, Cs) ( VI − VIII ), and AAuP 2 S 7 (A = K, Rb) ( IX, X ). I − III crystallize in the acentric space group…
The effect of oxide crystallinity on the oxidation rate of silicon carbide was investigated. CVD SiC coupons were oxidized in a clean TGA reactor system at 1300°C initially in flowing oxygen, immediately annealed in argon, and then reoxidized, all in situ and without cooling (so as to preserve oxide integrity). The pa…
(1997). BRIDGED POLYCYCLIC AROMATIC HYDROCARBONS. A REVIEW. Organic Preparations and Procedures International: Vol. 29, No. 3, pp. 243-283.
Novel aromatic polyimides containing symmetric, bulky di-tert-butyl substituents unit were synthesized from 1,4-bis(4-aminophenoxy)2,5-di-tert-butylbenzene (BADTB) and various aromatic tetracarboxylic dianhydrides by the conventional two-stage procedure that included ring-opening polyaddition in a polar solvent such a…
We investigate experimentally, using quasi–elastic light scattering the dynamical properties of highly swollen lamellar and “sponge" phases. In our system the structural sizes – smectic period for lamellar phases or characteristic cell size for “sponge" phases – may be changed continuously by adding solvent up to scal…
We use a model previously formulated based on the double-exchange mechanism and diagonal disorder to calculate magnetization and conductivity for ${\mathrm{La}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Sr}}_{\mathrm{x}}$${\mathrm{MnO}}_{3}$-type crystals as a function of temperature. We use the results of the mo…
The phosphoenolpyruvate (PEP) carboxykinase-encoding gene from the anaerobic, CO2-fixing, succinate-producing bacterium Anaerobiospirillum succiniciproducens was cloned, sequenced, and expressed in Escherichia coli. The gene encoded a 532-residue polypeptide with a calculated molecular mass of 58.7 kDa. The sequence o…
A systematic investigation of structure and intrinsic magnetic properties of the novel compounds R3(Fe, T)29 (R=Y, Ce, Nd, Sm, Gd, Tb, and Dy; T=V and Cr) has been performed. The lattice constants and unit cell volume decrease with increasing the rare-earth atomic number from R=Nd to Dy, except for Ce, reflecting the…
The melt-state phase behavior of isotactic polypropylene (i-PP) blended with a series of poly(ethylene/ethylethylene) random copolymers has been investigated using small-angle neutron scattering (SANS). These PEE xx copolymers, where xx is the percentage of ethylethylene (EE) units, were prepared by hydrogenation of a…
The luminescence of and doped with divalent manganese was studied by performing excitation, emission, and decay time measurements in the temperature range from 4.2 to 500 K. From the results of these measurements the following mechanism can be proposed. Excitation into the gallate host lattice leads to the formation o…
Water-soluble calix[4]arenes 10a,b with chromophores ("antenna") attached to the lower rim via a short spacer are described. In the neutral lanthanide complexes of 10a,b photoexcitation of the antenna induces lanthanide emission via intramolecular energy transfer. Calix[4]arene 10b with a chrysene moiety as sensitizer…
Abstract A high increase in the bulk polymerization rate of L,L‐lactide and racemic D,L‐lactide is observed when aluminium isopropoxide is added with an equimolar amount of a Lewis base, such as triphenylphosphine (P(ϕ) 3 ) and better 4‐picoline (C 6 H 7 N). Polylactide of high molecular weight and narrow molecular we…