Materials Literature
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Determination of the crystal structure of ethyl chlorophyllide a.2H(2)O by single crystal x-ray diffraction techniques has provided the first detailed molecular structural data available for a magnesium-containing derivative of chlorophyll. At the same time the aggregation observed in this structure serves as the basi…
Low-density polyethylene films strained up to 35% exhibit an initial increase of diffusivity and permeability which soon reach a maximum and subsequently drop to steadily decreasing values below those of the unstrained starting material. The sorption steadily increases and seems to approach a plateau. The maximum and…
Lattice vibrational dispersion curves for the ``intermolecular'' modes in the triclinic, one molecule per unit cell β phase of p-C6D4Cl2 and p-C6H4Cl2 have been obtained by inelastic neutron scattering. The deuterated sample was investigated at 295 and at 90°K and a linear extrapolation to 0°K was applied in order to…
Abstract Two Cu ++ centres in NH 4 Cl single crystals grown from acid (I) and neutral (II) aqueous solution were investigated by ESR and ENDOR at 4.2 °K. From the superhyperfine and quadrupole data obtained for several shells of neighbour nuclei the following centre models are proposed: in both centres Cu ++ is at an…
Abstract To demonstrate the cooperativity in the formation of an interpolymer complex, the stability of polyanion‐polycation complexes as a function of their chain length was studied. Poly(methacrylic acid) (PMAA; P̄ n ≈ 800) was used as source for the polyanion and quaternized alkylamines and polyethyleneimines with…
<div class="htmlview paragraph">This paper describes the results of durability tests of monolithic catalytic converters with mechanical devices used to tailor the exhaust gas flow. Deflectors of several different shapes show promise of extending the useful life of the converter by improving conversion efficienci…
Abstract The lattice dynamics of graphite have been studied using a tensor force model. Force constant values for interactions between atoms in‐plane have been transferred from the naphthalene molecule. It is shown that the agreement between theory and neutron scattering data is very good, indicating that the molecula…
Abstract The measurement of the polarization resistance using AC enables the corrosion losses to be determined with certain difficulties only, Despite that the AC methods are of technical interest because they allow the determination of corrosion rate/time curves without difficulties and enable potentiel fluctuation t…
Abstract The formation of polyion complexes in aqueous medium between polycations carrying charges in the chain backbone and poly(carboxylic acid)s, such as poly(methacrylic acid) (PMAA), poly(carboxylic acid) (PAA), and poly(itaconic acid) (PIA), were studied. It was found that polycations formed more stable complexe…
The two-dimensional solubility parameter approach has been applied to the prediction of solubility of one polymer in another. The solubility parameters of a number of polymers have been calculated and the second dimension shown to improve the agreement between the calculated solubility and that measured using a ternar…
The effect on the diffusion coefficient of nondissipative interactions between diffusing macromolecules is evaluated for two-component solvent-macromolecule solutions. For linear concentration gradients, the generalized Stokes-Einstein relation is obtained from purely microscopic arguments. Application of these result…
Hydrothermal experiments with fresh basalt in a high pS 2 environment yielded cordierite–sulfide-bearing assemblages. These results suggest that during thermal metamorphism of a volcanic exhalative sulfide deposit, progressive sulfurization of the enclosing basalts takes place. Cordierite–anthophyllite and cordierite–…
An extensive computer program has been developed to check the internal consistency of published, numeric, crystallographic data prior to storage in the data files of the Cambridge Crystallographic Data Centre. The coding is in Fortran IV for an IBM 3701165 with 1 megabyte store. The atomic coordinates, constitution an…
Abstract A mathematical representation of the plasticating process in a reciprocating‐screw injection‐molding machine has been formulated as a design tool for simulating the effect of processing parameters on the melting performance, the melt temperature, and the pressure profile. Comparisons with experimental data on…
The dose dependence of the lattice parameter change for neutron-irradiated copper has been measured in the range (1.0–10.8)×1018 neutrons/cm2. The lattice parameter changes were measured directly by using a multiply reflecting monochromator, and an analysis of the effects of misalignment in the geometry has been given…
Longitudinal and transverse relaxation times of 119Sn have been measured as a function of temperature at several field strengths in SnCl4, SnBr4, and SnI4. T2 in all three liquids is field independent and is governed by scalar coupling to the halogen. T1 is strongly field dependent in SnBr4 and SnI4 and exhibits a min…
Crystallization during melt spinning is studied as an example of the nonisothermal crystallization of polymers. The following equation is derived, taking the temperature distribution within a filament into consideration: where T = temperature, X = crystallinity, κ = thermal diffusivity, V = velocity, ΔH = heat of crys…
The packings considered in this paper are packings of a unit sphere in iV-dimensional Euclidean space by an infinite number of unequal spheres. More specifically, we are interested in complete packings, those which exhaust the volume of the packed sphere.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPorphyrin-annulene redox-related ligand pair. Electrochemical synthesis and characterization of the reduction products of the cobalt, copper, and nickel complexes of a tetraaza[16]annuleneNurhan Takvoryan, Keith Farmery, Vladimir Katovic, Frank V. Lovecchio, Ernest S. Gore,…
In a study on the mechanism of pitting corrosion, a gas evolution in the pit has been observed. This gas has been gaschromatographically identified as hydrogen. The explanation of the evolution of hydrogen by the acidification of the pit electrolyte and the potential drop across the pit have been experimentally proved…