Materials Literature
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The purpose of this study is the characterization of fly ashes produced by Spanish thermoelectric power plants, according to sampling taken in 1981 and 1982. The study takes in the following characteristics: physical characteristics (size distribution of particles, ...); chemical ones (chemical analysis...); and miner…
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A procedure for the determination of sulphides attackable by HCI (1 :3) in cements by means of a potentiometric determination with a selective electrodo of sulphides, is proposed.
The relaxivity, biodistribution, and toxicity of the gadolinium-tetraazacyclododecanetetraacetic acid (Gd-DOTA) complex were evaluated. This cyclic complex has much greater in vitro stability (10(28)) than similar noncyclic complexes such as gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA) (10(23)) or gadoliniu…
For a solid containing preexisting flaws, overall nonlinear constitutive relations are developed on the basis of a model which endows a preexisting flaw with frictional and cohesive resistance, and which includes nucleation and growth of tension cracks at the preexisting flaw, as it deforms under the action of an over…
Abstract Results are given of an assessment of a Rietveld-type X-ray powder diffraction pattern fitting structure refinement technique for assaying powdered mixtures as an alternative to conventional discrete peak empirical methods of the type described by Klug and Alexander (1974) and Chung (1974). The values obtaine…
Abstract Oxygen semipermeability of LnCoO3-based perovskite-type oxides changed drastically by the partial substitution of A site and B site cations, Ba and Cu being the most effective substituents, respectively. Host rare earth cations (Ln) also affected the oxygen semipermeability, which increased with a decrease in…
We study the statistics of a grafted polymer brush, consisting of a set of monodisperse chains in solution, each attached irreversibly by one end to a flat surface. We use a self-consistent field method, valid in the limit of weak excluded volume and at moderately high surface coverage. Exploiting the fact that the ch…
Three methods have been used to extract iron (Fe) and aluminium (Al) from a wide range of soils. The three extractants were pyrophosphate reagent (p), acid-oxalate reagent (o), and dithionite-citrate reagent (d), and each reagent is thought to extract different forms of Fe and Al. The forms of Fe in the soils were stu…
The phase diagram and dynamical properties of systems of particles interacting through a repulsive screened Coulomb (Yukawa) potential have been calculated using molecular and lattice dynamics techniques. The phase diagram contains both a melting transition and a transition from fcc to bcc crystalline phases. These ph…
Continuum Damage Mechanics (C.D.M.) has developed continuously since the early works of Kachanov and Rabotnov. It constitutes a practical tool to take into account the various damaging processes in materials and structures at a macroscopic continuum level. The main basic features of C.D.M. are considered in the first…
The relationship between magnetic properties of rare-earth metals and the electron structure of the f shell is considered. Simple concepts are used to show how many-electron quantum numbers of the spin, orbital and total angular momenta of the f shell are related to the Curie temperature, magnetic moment, magnetic ani…
Deoxycytidylate (dCMP) hydroxymethylase from Escherichia coli infected with a T-4 bacteriophage amber mutant has been purified to homogeneity. It is a dimer with a subunit molecular weight of 28,000. Chemical modification of the homogeneous enzyme with N-ethylmaleimide (NEM) and 5,5'-dithiobis(2-nitrobenzoic acid) (DT…
While X-ray crystallographic data on cytochrome c show the reduced and oxidized forms to have very similar structures, there is a considerable body of data, mostly from solution studies, that indicates the reduced form is more stable and that the interior of the protein is less accessible to solvent in this state. The…
The thermal expansivity of zircon-type scandium vanadate (ScVO 4 ) was determined by the X-ray powder diffraction method in the temperature range 300-634 K. The thermal expansion is anisotropic at room temperature as it has a larger coefficient of expansion along the a direction than along the perpendicular direction…
Conductivity, thermoelectric power and Hall effect measurements are reported for V 2 O 5 gels with relative concentrations of V 4+ of 0.005 and 0.11. Both the Seebeck and the Hall coefficient are negative. This is an exception to the rule that the sign anomaly effect should be observed for amorphous semiconductors, i.…
Abstract Poly(1,5‐hexadiene) was prepared and its structure characterized by high‐field 13 C nuclear magnetic resonance. The polymer was shown to contain repeating five‐membered rings separated by methylene bridges, with both cis and trans placements present in a 54 : 46 ratio. The result is compatible with the Marvel…
Abstract The packing densities (Van der Waals volume/molar volume) were determined at 293 K for various epoxide–amine stoichiometric networks. They are noticeably higher than those of linear polymers except strongly hydrogen bonded ones [polyamides, poly(vinyl alcohol)]. By extrapolation of the dilatometric data, it w…
The authors report measurements of both the AC and the DC electrical conductivity of polymeric insulator-conductor composites in a broad range of compositions for frequencies between 1 kHz and 1 MHz. The dependence of the DC conductivity with the additive concentration exhibits a crossover, from a traditional percolat…
The phase transition of an isotropic liquid into an anisotropic phase is described in terms of a bifurcation of the solution of an exact nonlinear integral equation for the pair distribution function. The behaviour of the correlation function of orientational fluctuations for the pair distribution function is analysed.