Materials Literature
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A series expression is developed for the fourth moment of a beamed field incident on a random phase screen or an extended medium. The series has a symmetry that allows its first few terms to generate useful approximations at both low and high spatial frequency. The parabolic wave equation, the Markov approximation, an…
Abstract Clinoptilolite, Ca x (Na,K) 6‐2 x {Al 6 Si 30 O 72 }·24H 2 O, frequently has been recognized in Cenozoic volcanogenic sedimentary rocks; however, its occurrence in soils has received little attention. In the course of this study, clinoptilolite was identified in calcareous soils derived from volcanic‐rich sed…
A theoretical analysis of the oscillating voltage at twice the Larmor frequency (2ω 0 ), due to quadrupolar polarization of 14 N nuclei, predicts a signal at least ten orders of magnitude smaller than the magnetic-induction signal produced by the same sample. However, nonsecular parts of the quadrupolar interaction ar…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparation and characterization of an iron(III) porphyrin N-oxideJohn T. Groves and Yoshihito. WatanabeCite this: J. Am. Chem. Soc. 1986, 108, 24, 7836–7837Publication Date (Print):November 1, 1986Publication History Published online1 May 2002Published inissue 1 November 19…
A comparison of freshwater and marine Gomphonema species has shown that the ecological separation is accompanied by a morphological one. They have only been assigned to the same genus because they all have heteropolar, cuneate cells, which are attached to the substratum by a mucilage pad or stalk. The marine taxa can…
Abstract 13 C‐NMR spectra of trityl cellulose (Tr‐Cell), tosyl cellulose (Ts‐Cell), cellulose S‐methyl xanthate (Cell‐M‐Xan), and cellulose formate (CF) in dimethylsulfoxide‐ d 6 were analyzed at 50.4 MHz. It was found that the distribution of substituents in the anhydroglucose units of these cellulose derivatives can…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNMR of phosphorus-31 heteroatoms in paramagnetic 1-electron heteropoly blues. Rates of intra- and intercomplex electron transfers. Factors affecting line widthsMariusz. Kozik, Charles F. Hammer, and Louis C. W. BakerCite this: J. Am. Chem. Soc. 1986, 108, 24, 7627–7630Public…
ADVERTISEMENT RETURN TO ISSUEPREVArticlePhotoresponsive polymers. Reversible bending of rod-shaped acrylamide gels in an electric fieldMasahiro IrieCite this: Macromolecules 1986, 19, 11, 2890–2892Publication Date (Print):November 1, 1986Publication History Published online1 May 2002Published inissue 1 November 1986ht…
The classical polarizability theory of optical activity in crystals is elaborated and a method of calculating rotatory power from crystal structure data is described. By varying the polarizabilities of the atoms within reasonable limits, optical rotatory powers are computed for crystals of α-quartz, AlPO4, cinnabar, B…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTrialkoxynitridomolybdenum compounds: (RO)3Mo.ident.N. Preparation, structures (R = tert-Bu and iso-Pr), and comparisons with a tungsten analog (R = tert-Bu)Dominic M. T. Chan, Malcolm H. Chisholm, Kirsten Folting, John C. Huffman, and Nancy S. MarchantCite this: Inorg. Chem…
An earlier procedure for calculating homogenization during the solidification of binary alloys is extended to include more realistic assumptions for dendrite arm coarsening kinetics and the partition coefficient. Dendrite coarsening is shown to follow the usual exponential function which differs from that relating fin…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of structural disorder on organic superconductors: a neutron diffraction body of "high-Tc" .beta.*-(bis(ethylenedithio)tetrathiafulvalene)2 triiodide at 4.5 K and 1.5 kbarArthur J. Schultz, Hau H. Wang, Jack M. Williams, and Alain. FilholCite this: J. Am. Chem. Soc. 1…
The properties of vacancies, self-interstitial atoms and translation stacking faults have been studied by computer simulation using the n-body empirical potentials recently developed for the body-centred-cubic transition metals by Finnis and Sinclair. Vacancy formation energy, formation volume and migration energy hav…
Viscometry, crystal growth kinetics, and glass powder sintering were used to determine the activation energies of viscous flow, crystal growth, and sintering behavior of a standard NBS 710 glass and two crystallizable glass powders in the calciaaluminosilicate system. In a system which sintered successfully to zero po…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermodynamic and structural studies of configurational isomers of (1,4,8,11-tetraazacyclotetradecane)nickel(2+)E. Kent Barefield, Antonio Bianchi, E. Joseph Billo, Peter J. Connolly, Piero Paoletti, Jack S. Summers, and Donald G. Van DerveerCite this: Inorg. Chem. 1986, 25,…
Abstract The efficiency of several porphyrins at 10 μ M and 83 μ M as sensitizers of the photooxidation of 0.1 m M tryptophan and histidine via a singlet oxygen‐mechanism was studied in pH 7.4‐buffered aqueous solutions and in aqueous dispersions of Triton X‐100 micelles. The porphyrins were either solubilized in the…
A statistical model of microstructural evolution is developed for the evolution of grain structure during deposition. In cases where the atomic mobility on the surface greatly exceeds that in the bulk of the film, the bulk microstructure may be viewed as static while all of the evolution is controlled by the free surf…
Abstract Porphycene and a tetra‐n‐propyl derivative remained unaltered on irradiation in toluene at room temperature. Quantum yields of fluorescence, S T intersystem crossing, and singlet molecular oxygen sensitization, as well as lifetimes of the singlet and triplet excited states were measured. In view of their stru…
First experiments show that cross-linked liquid-crystalline polymers, which are swollen with nematic low molar mass liquid crystals and freely dispersed in this liquid crystal, change their shape if an electic field is applied. This shape variation depends on the degree of swelling.
Abstract The anionic ring‐opening polymerization of 2,2‐dimethyltrimethylene carbonate in solution with sec ‐butyllithium as initiator was found to result under suitable conditions in a bimodal molecular weight distribution, vic. cyclic oligomers and a high‐molecular‐weight polymer. The concentration of cyclic oligome…