Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNitrogen charge distributions in free-base porphyrins, metalloporphyrins, and their reduced analogs observed by x-ray photoelectron spectroscopyD. H. Karweik and N. WinogradCite this: Inorg. Chem. 1976, 15, 10, 2336–2342Publication Date (Print):October 1, 1976Publication His…
Abstract Structure is taken as the main theme in outlining the mechanical properties of polymer composites. Examples of two‐component polymer systems are selected from the literature showing their morphology, as evidenced from electron micrographs, and their corresponding mechanical properties, as evidenced by dynamic…
In order to analyze experimental data of torque measurements for magnetic thin films, a (L/H)2-vs-L plot is proposed, where L represents the torque of a film in a field of H whose direction is 45° to the film plane. The saturation magnetization M and perpendicular anisotropy energy K⊥ are obtained without any approxim…
Twenty-two proteins available to this laboratory were examined for their ability to crystallize from polyethylene glycol (PEG). Of the 22, 8 had been crystallized previously by conventional means and the remainder had yielded no crystals by other methods. Using a single broad screen with four different concentrations…
The spin-Peierls transition is considered as a progressive spin-lattice dimerization occurring below a transition temperature in a system of one-dimensional antiferromagnetic Heisenberg chains. In the simplest theories, the transition is second order and the ground state is a singlet with a magnetic gap. The historica…
Progress in the field of reflective multilayer coatings for the wavelength region between 50 A and 2000 A is reviewed. All the coatings contain absorbing materials, absorption losses are minimized by positioning strongly absorbing materials into the nodes of the standing wave inside the coating. Above lambda = 1200 A,…
Monte Carlo results are presented for the free energy and dielectric constant of systems of permanent dipoles disposed on the sites of simple cubic and face-centred cubic lattices as functions of the parameter ϑ = μ2ρ/kT. Alternative schemes are considered for taking account of the long-range character of the dipolar…
The hexagonal cell dimensions a and c of 2H-MoS2, 2H-MoSe2 and 2H-WSe2 have been measured over the temperature range 20 to 800 °C. In all three compounds a and c increased non-linearly with temperature, the linear thermal expansion coefficient of c being greater than that of a. Above 500°C the compounds begin to decom…
ABSTRACT Determinations were made of several physical properties of the viscid and frame silks of the orb-webs built by the spider Araneus sericatus (Cl.). Both types of silk show a breaking stress of approximately 1 GN/m2 and an initial resilience of approximately 0·35. The breaking extension ratio of viscid silk (λ…
Abstract not Available.
Procedures for the preparation of soluble collagen from rat skin and tail tendon were reviewed and revised to permit the preparation of native monomeric collagen with intact nonhelical ends. The degree of intactness was estimated from the tyrosine content, which is present only in the nonhelical ends, and by mobility…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanism of the quenching of the emission of substituted polypyridineruthenium(II) complexes by iron(III), chromium(III), and europium(III) ionsC. T. Lin, W. Boettcher, M. Chou, C. Creutz, and N. SutinCite this: J. Am. Chem. Soc. 1976, 98, 21, 6536–6544Publication Date (Pri…
A set of central interionic potentials for the rubidium halides is presented. These potentials, which are based on a shell-model description, are fitted to solid state data and are used in molecular dynamics simulations of the ionic melts. The partial radial distribution functions, the velocity autocorrelation functio…
The nature of the charge carriers in n-type BaTiO 3 is discussed in the light of recent investigations into their mobility (T<or=1500K) and defect chemistry. Evidence is found for small polaron formation. Mobility enhancement-probably due to correlated hopping-must be assumed in order to furnish a consistent explanati…
The ${[\mathrm{Li}]}^{0}$ center has been formed in lithium-doped single crystals of MgO by high temperature quenching. In contrast to the ${[\mathrm{Li}]}^{0}$ center formed by low-temperature $\ensuremath{\gamma}$ irradiation, the center formed by quenching is stable at room temperature. A heavy electron irradiation…
A pressure-induced tricritical point is indicated for ${\mathrm{KH}}_{2}$${\mathrm{PO}}_{4}$ near 2 kbar pressure. This estimate is based on analysis of our static dielectric data for pressures up to 3 kbar.
The existence of a hexagonal (wurtzite) form of silicon, similar to that form of diamond (carbon) observed in meteorites and in the laboratory, has been identified by x-ray diffraction in reaction-bonded silicon nitride containing unreacted silicon. The presence of this phase is due to stresses created in the silicon…
Polyphosphazenes are emerging as a new class of macromolecules that have an obvious future as technological elastomers, films, fibers, and textile treatment agents. However, they also possess almost unique attributes for use in biomedicine as reconstructive plastics or as drug-carrier molecules. Moreover, their possib…
With glass capillary pressure vessels it has been possible to study the effect of pressure on the temperature of maximum density (TMD) and on the "sharpness" of the density maximum in liquid H(2)O and D(2)O in the important but little-studied supercooled regime. A pressure of 1200 bars produces a 33 degrees C depressi…
High-purity Ni is used for quenching experiments in a He cryostat, the electrical resistivity being used as a defect indicator. The quenched-in resistivity recovers in two stages: a steep one, A, around 120°C with a decrease of 50% and a rather broad one, B, around 560°C with a decrease of 45%. The formation energy of…