Materials Literature
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Femtosecond differential absorption measurements of the quantum-confined transitions in CdSe microcrystallites are reported. Spectral hole burning is observed, which is accompanied by an induced absorption feature on the high-energy side. The spectral position of the burned hole depends on the excitation wavelength. F…
An automatic procedure for building a protein polyalanine backbone from C alpha positions and 'spare parts' retrieved from a data base of 66 high-resolution protein structures is described. Protein backbones are constructed from overlapping fragments of variable length, which allows the backbone of regular secondary s…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemistry of yttrium triisopropoxide revisited. Characterization and crystal structure of Y5(.mu.5-O)(.mu.3-OPr-iso)4(.mu.2-OPr-iso)4(OPr-iso)5Olivier Poncelet, William J. Sartain, Liliane G. Hubert-Pfalzgraf, Kirsten Folting, and Kenneth G. CaultonCite this: Inorg. Chem. 19…
A detailed description of the method of crystallographic refinement by simulated annealing is presented. To test the method, it has been applied to a 1.5 Å resolution X-ray structure of crambin. The dependence of the success of the simulated annealing protocol with respect to the temperature of the heating stage is di…
Relaxation and diffusion in restricted geometrics excitation energy transfer and photoinduced electron transfer phenomena in some confined systems electron excitation transport in micelles, polymers, and multilayers electron excitation transport on polymer chains polymer structure and downchain electronic energy trans…
Careful experimental techniques, especially with synchrotron radiation, give well-resolved diffraction patterns. Remaining overlapping peaks can be separated by profile analysis and profile fitting. The mathematical formalism is given. The derived parameters are: peak positions for lattice constants, integrated intens…
L'agent de surface a pour role de stabiliser la mousse avant gelification. Influence d'agents de surface sur des proprietes de surface de mousses phenoliques
The wetting by a liquid drop of a model mammalian hair fibre is compared with that of a smooth cylindrical fibre. (B. J. Carroll, J. Collodid Interface Sci., 1976, 57, 488). The model considered has a series of axially symmertrical serrations regularly spaced along the fibre length and these are shown to play an impor…
Thermogravimetric (TG) data on reoxidation behaviour of a particular type of sponge iron (coal based sponge iron) are mainly reported in this paper. While emphasis is on isothermal kinetics, some nonisothermal TG data are also presented. The data have been analysed using the reduced time plot and the activation energy…
Abstract Recent research of the well‐drained cerrados (savanna) soils of Brazil suggests that poor root growth associated with inferior crop production is often caused by subsoil Ca deficiency rather than Al toxicity. The present study was conducted to re‐examine this hypothesis and to compare native soil vegetation p…
The effect of a magnetic field applied perpendicular to the helical axis of a cholesteric liquid crystal mixture with positive diamagnetic anisotropy has been studied by laser diffraction and microscopy. A rapid decrease of the field below a threshold H s generates first a metastable periodically striated texture. A f…
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Chlorided Pt/Al2O3 has been subjected to series of consecutive oxychlorination/reduction cycles in which oxychlorination stages in each series involved heat treatment of Pt/Al2O3 at 723, 893 or 993 K in oxygen containing 400 ppm carbon tetrachloride. The quality of resulting Pt dispersion was monitored by infrared and…
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In searching the elements to suppress the intergranular brittleness in molybdenum, TiC addition was found effective. In order to clarify the effect of TiC addition quantitatively, molybdenum bicrystals containing 1.5 mol%TiC were prepared by a floating zone melt technique. The fracture behaviour was measured by a 4-po…
Abstract Das thermische Verhalten von RbGeI 3 wurde unter Verwendung von Röntgenbeugung, Ramanspektroskopie und DTA/DSC untersucht. RbGeI 3 ist tetramorph. In der Kristallstruktur der gelben orthorhombischen LT‐Form (RG P2 1 2 1 2 1 ; a = 10,1441 (8) Å; b = 4,5460(5) Å; c = 16,8438(9) Å), die durch Kristallisation aus…
A simple method which is suitable for determining with reasonable precision the lattice parameters of the crystals with known structure using a 16-bit personal computer and an unsophisticated calculation is described. This procedure is based on the Nelson-Riley extrapolation function and the least-squares analysis. Th…
The effects of maleic and fumaric acids and their mono- and di-anions on the dissolution of calcite in aqueous solution have been studied over a wide pH range (3–8.5) by (i) the channel flow cell method, (ii) etch pit morphology measurements and (iii) the determination of adsorption isotherms. It is established that t…
Abstrac tAn improved model for the atomic oxygen oxidation of silver is presented. The transport of oxygen through the oxide layer is modelled using two transport mechanisms, namely gas flow through micro-pores and Fickian diffusion. Both processes exhibit parabolic growth. The interfacial reaction between oxygen and…
Various NADH model compounds, 1-(X-benzyl)-1,4-dihydronicotinamide (X-BNAH: X = 4-MeO, 4-Me, H, 4-Cl2, and 2,4-Cl2) and 10-methyl-9,10-dihydroacridine (AcrH2), form complexes with metalloporphyrins (FeTPPClO4, FeTPPCl, MnTPPClO4, and ZnTPP; TPP: tetraphenylporphyrin) in dichloromethane or chloroform. For the BNAH–ZnTP…