Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDinuclear copper(II) cryptates of macrocyclic ligands: synthesis, crystal structure, and magnetic properties. Mechanism of the exchange interaction through bridging azido ligandsJacques Comarmond, Pierre Plumere, Jean Marie Lehn, Yvette Agnus, Remy Louis, Raymond Weiss, Oliv…
X-ray data have been extended to 1.7 A for a binary complex of Escherichia coli dihydrofolate reductase with methotrexate and a ternary complex of Lactobacillus casei dihydrofolate reductase with methotrexate and NADPH. Models for both structures have been refined to R factors of 0.15 and include parameters for fixed…
The CNDO/S3 model, a spectroscopically parametrized complete neglect of differential overlap molecular orbital method, is extended to encompass the description of radical cation states in infinite periodic quasi-one-dimensional molecules. Detailed model calculations of the energy bands and density of valence electron…
The role of hydrogen gas in influencing fatigue-crack propagation is examined for several classes of lower strength pressure-vessel and piping steels. Based on measurements over a wide range of growth rates from 10−8 to 10−2 mm/cycle, crack-propagation rates are found to be significantly higher in dehumidified gaseous…
In a homeotropic nematic cell, a solitarylike director wave is excited by a mechanical method. Three photographs of the wave propagation process and measured velocity-time dependence curves are presented. By means of the interference patterns of focused polarized light, it was found that the dark lines observed in whi…
The reactions of 1,2- and 1,3-dithioles, HSRSH, with Fo 3 (CO) 12 give the dinuclear compounds Fe 2 (CO) 6 (SRS) in good yields. With R = C 2 H 4 or R = C 3 H 6 the trinuclear compounds (CO) 3 Fe(SRS)Fe(CO)(SRS)Fe(CO) 3 containing an open Fe 3 chain are obtained.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanism of stickiness in hygroscopic, amorphous powdersGalen E. Downton, Jose L. Flores-Luna, and C. Judson KingCite this: Ind. Eng. Chem. Fundamen. 1982, 21, 4, 447–451Publication Date (Print):November 1, 1982Publication History Published online1 May 2002Published inissue…
It is proposed that the grain-size dependence of the yield stress of metals is due to the elastic incompatibility stresses at the grain boundaries. For clarity, the process of yielding is divided into three stages. In the first stage (prior to microyielding), the differences in elastic properties arising from the elas…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNonplanar conformers and the phase behavior of solid n-alkanesMark Maroncelli, Song Ping Qi, Herbert L. Strauss, and Robert G. SnyderCite this: J. Am. Chem. Soc. 1982, 104, 23, 6237–6247Publication Date (Print):November 1, 1982Publication History Published online1 May 2002Pu…
Very high and broad Curie maxima are observed in ceramic Ba(Ti1‐yZry)O3 mixed crystals, which are often used for the preparation of ceramic dielectrics. The ferroelectric‐to‐paraelectric phase transition of ceramic Ba(Ti1‐yZry)O3 was studied using dielectric measurements, quantitative DTA, X‐ray diffraction, and deter…
The modification of the absorption, emission, and Raman scattering intensities of molecules near metal surfaces is discussed with emphasis on the last. These modifications are usually referred to as surface selection rules. We show that in Raman scattering, the ‘‘rule,’’ which states that only those modes will be acti…
Silicon–oxygen and aluminum–oxygen compounds exhibit significant XPS Auger and photoelectron chemical shifts that are accurately measurable. Chemical state plots of KLL Auger kinetic energy versus 2p photoelectron energy permit identification of chemical species from the locations of their points on the plots. The KLL…
Presents results of a detailed theoretical survey of the defect structure and transport properties of non-stoichiometric beta Al 2 O 3 . The authors methods are based on a generalised mott-Littleton approach which includes a full explicit treatment of lattice relaxation around defect species. Their calculations show t…
The three-dimensional structure of a penicillin-sensitive D-alanyl-carboxypeptidase-transpeptidase has been determined by x-ray crystallography to a resolution of 2.8 angstroms. The site of binding of the beta-lactam antibiotics penicillin and cephalosporin has been located. These findings constitute direct observatio…
An electron transmission experiment is used to study the low-energy total cross sections in Na, K, Rb, Cs and Hg. A shape resonance is observed in Na at 0.08+or-0.02 eV and in Hg at 0.42+or-0.03 eV. In Rb evidence is found for the existence of a shape resonance below 0.05 eV. The results are compared with the availabl…
The dynamic structure factor and its generalization for transverse excitations for the normal modes of a Lennard-Jones glass are calculated. The results are compared with those for a polycrystal. The longitudinal dispersion curve shows a remarkably deep minimum at the wave vector where the structure factor has a peak.
Incoherent quasielastic neutron scattering (IQNS) has been used to investigate the molecular motions of adamantanone in its plastic phase. They can be described on the basis of a model allowing 120° jumps around the crystallographic [111] directions together with 90° rotations around the molecular twofold symmetry axi…
Abstract The copolymerization of monomethyl intaconate (MMI) with styrene (St) initiated with 2,2′‐azoisobutyronitrile in solvents differing in dielectric constants and capability to form hydrogen bonds was investigated. The IR‐ and 1 H NMR spectroscopic studies of the monomer mixtures in four solvents have shown an i…
NMR spectra from $2H$-Ta${\mathrm{Se}}_{2}$ are analyzed to obtain charge-density-wave parameters versus temperature. It is shown that there is a major orthorhombic distortion within each Se-Ta-Se layer, implying unexpectedly strong interlayer coupling. Evidence is also given for the existence of a significant interac…
Abstract The synthesis and phase behaviour of a series of polymers having liquid crystalline sidechains and a poly(acrylic acid) backbone are described. These polymers show a dependence of the phase transition temperatures on molecular weight. In copolymers of two liquid crystalline acrylic esters, induced smectic pha…