Materials Literature
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Abstract The adsorption of aminotriazole, at its solution pH, with montmorillonite saturated with different cations has been studied. A pesticide-montmorillonite complex is formed through interlamellar cations which are not displaced. Aminotriazole is situated mostly as a polarized molecule around Mg 2+ and Zn 2+ cati…
The Long Duration Exposure Facility (LDEF) spacecraft represents the first controlled unidirectional exposure of high-fluence atomic oxygen on fluorinated ethylene propylene (FEP Teflon) and silicones. The atomic oxygen erosion yield for FEP Teflon was found to be significantly in excess of previous low fluence orbita…
Abstract Die metallisch glänzenden Verbindungen Sr 2 Sn 2 As 2 und Sr 0,87 Ba 0,13 Sn 2 As 2 wurden aus Schmelzreaktionen ausgehend von den Elementen erhalten. Sie kristallisieren trigonal rhomboedrisch, Raumgruppe R3m, Z = 3, mit den Gitterkonstanten: In den Kristallstrukturen der isotypen Verbindungen bilden dreibin…
The 7475 Al–0·7Zr (wt-%) cold rolled alloy sheet fabricated by powder metallurgy exhibited remarkable superplasticity for strain rates between 2×10−3 and 3×10−1 s−1 at 793 K. During the initial deformation stage, the strain rate sensitivity m increased with increasing strain and attained a value greater than 0·5 after…
We discuss the role of both primary and secondary order parameters in a transition between two solid phases. We show how microscopic distortions which appear at the transition can be calculated using group-theoretical methods. We also show how the form of the coupling term in the Landau free energy influences the beha…
The concept of the capacitance of a gaseous void is discussed as applied to electrical insulation science. The most pertinent aspect of the capacitance definition is that of reference to a single-valued potential difference between surfaces. This implies that these surfaces must be surfaces of equipotential. With this…
Modulated reflection spectra of passive films on Fe‐20Cr‐25Ni alloy have been measured in 1 kmol · m −3 (pH 0.1), 1 kmol · m −3 (pH 2.0, 6.0, and 9.5), and 0.1 kmol · m −3 (pH 13.1) solutions, respectively. Quantitative relations between the characteristic of spectra and the composition of the films have been derived…
Abstract Riet veld X-ray powder diffraction (XRD) analysis has been evaluated as a procedure for characterizing Al-substituted goethite according to the Rietveld scale factor, unit-cell parameters, and atom positional parameters. The study was conducted with three synthetic goethite samples for which the degree of Al…
Qualitative and quantitative analysis of nanogram amounts of substances by transmission infrared spectroscopy with the use of silver island films was carried out. The effect of silver thickness, the comparison of several plates (Ge, BaF 2 , and ZnSe), the dynamic range of intensity enhancement vs. sample amount, and t…
Ab initio calculations are presented of the cohesive energies of aluminium in a number of diverse hypothetical structures which span a wide range of the coordination number, C , from C = 0 to C = 12. The calculations have been performed to investigate the nature of multi-atom bonding, its dependence on C and to form a…
The mechanism of formation of positive corona onset pulses in SF/sub 6/ at 100 kPa is examined. A constant positive voltage of 50 kV is applied to an 0.5-cm diameter sphere located 6.5 cm from a grounded plane. The calculated current pulse has a width at half maximum amplitude of approximately 0.3 ns, thus explaining…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTImproved metalation of 2,4,6-tribromoanisole: synthesis of 2-methoxyresorcinolKenneth GreenCite this: J. Org. Chem. 1991, 56, 13, 4325–4326Publication Date (Print):June 1, 1991Publication History Published online1 May 2002Published inissue 1 June 1991https://pubs.acs.org/doi…
The nitridation kinetics of Si powder compacts were studied by measuring the flow rate dependence of N 2 and N 2 –H 2 gas mixtures during slow heating of Si compacts while simultaneously monitoring the oxygen partial pressure of the egress gas. The reaction was found to occur in two distinct stages. In pure nitrogen t…
Abstract Fragmentation of support/catalyst particles during propylene bulk polymerization is analyzed by means of a mathematical model including energy and mass balances, with chemical reaction. The rupture phenomenon is specifically considered by the model and analyzed as it proceeds along time. Model predictions con…
Abstract A comparative study of the effects of catalyst fragmentation in the gas phase and bulk polymerization processes in performed. Typical operating conditions for each process are used for the comparison. The monomer concentration in the bulk process is nearly one order of magnitude larger than that in the gas ph…
Abstract Polyphosphate esters containing ferrocene structures were synthesized from 1,1′‐bis ( p ‐hydroxyphenylamido) ferrocene and 1,1′‐bis ( p ‐hydroxyphenoxycarbonyl) ferrocene with aryl phosphorodichloridates by interfacial polycondensation using a phase transfer catalyst. The polymers were characterized by infrar…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDeconvolution of x-ray diffraction data to elucidate plastic deformation mechanisms in the uniaxial extension of bulk nylon 6A. Galeski, A. S. Argon, and R. E. CohenCite this: Macromolecules 1991, 24, 13, 3945–3952Publication Date (Print):June 1, 1991Publication History Publ…
Equilibrium axial-radial director fields of a nematic liquid crystal confined to micrometer cylindrical cavities are examined in the approximation of one elastic constant K and spatially homogeneous nematic order parameter. It is shown that, in the strong-anchoring regime with homeotropic boundary conditions, a metast…
The combined build-up and attenuation factor, B exp (-mu r), of point isotropic photon sources in a water medium has been calculated using the Monte Carlo method, for energies (20-1500 keV) and distances (1-10 cm) relevant in brachytherapy. For the transport of photons and electrons, up-to-date and self-consistent tot…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPorphyrins-cyclodextrin. 2. Dissociation, reduction, and proton relaxivity of an iron(III) porphyrin .mu.-oxo dimer in cyclodextrin solutionsS. Mosseri, J. C. Mialocq, B. Perly, and P. HambrightCite this: J. Phys. Chem. 1991, 95, 12, 4659–4663Publication Date (Print):June 1,…