Materials Literature
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Abstract To test the possibility that the structural Fe 3+ in clay minerals can be biologically reduced, nontronite was mixed with sucrose and an aqueous extract from a Chinese paddy soil and incubated for 14 d at room temperature. Reflectance spectra, x‐ray diffraction patterns and Fe 2+ /Fe 3+ ratios were determined…
Preparation de nouveaux complexes verts de cerium(IV) dans lesquels le metal est pris en sandwich entre deux coordinats macrocycliques differents (une porphyrine et une phtalocyanine) ont ete prepares et caracterises par spectroscopie UV-visible, RMN du proton, voltammetrie cyclique et diffraction RX a −100°C. Une oxy…
The techniques of differential scanning calorimetry and electron microscopy were combined to locate collagens with different thermal stabilities in bovine dermis. When calfskin was heated at 1.25 degrees C/min, denatured cores developed in the fibrils at 65 degrees C, leaving native-banded sheaths. Coincident with the…
The electrical resistivity of bulk GexTe100-x glasses has been measured as a function of temperature and pressure. Under high pressure, all the glasses were found to undergo sharp discontinuous transitions from glassy semiconductors to crystalline metal. Several of the observed properties such as the transition pressu…
By means of detailed calculations with the Finnis-Sinclair potential and short-memory augmented rate theory we have investigated the isotope effect for vacancy diffusion in b.c.c. α-Fe. The experimental value is consistent with a model in which a double barrier bars the diffusion path.
Abstract An improved synthesis for 5,10,15,20‐tetrakis(pentafluorophenyl)porphyrin, 5,10,15,20–tetrakis(2,4,6‐trimethylphenyl)porphyrin and 5,10,15,20‐tetrakis(2,6‐dichlorophenyl)porphyrin by an acid‐catalysed condensation of pyrrole and properly substituted aldehyde, followed by oxidation, is reported, with yields of…
The spin-gas model of liquid crystals is employed to describe and explain single, double and quadruple reentrances of nematic and smectic phases, as well as reentrances below the monolayer smectic A1 phase, all of which are observed experimentally. New sextuple (and octuple) reentrances are predicted in the sequence n…
Abstract Cs 4 Sn 5 S 12 · 2 H 2 O wurde durch hydrothermale Reaktion von Cs 2 CO 3 mit SnS 2 bei einer Temperatur von 130°C dargestellt. Eine Röntgenstrukturanalyse ergab, daß die Verbindung schichtartige Polythiostannat(IV)‐Anionen [Sn 5 S ]∞ beinhaltet, in denen die Grundelemente trigonale SnS 5 ‐Bipyramide sowie Sn…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTX-ray analysis of the structure of the thermotropic copolyester XYDARJohn Blackwell, H. M. Cheng, and A. BiswasCite this: Macromolecules 1988, 21, 1, 39–45Publication Date (Print):January 1, 1988Publication History Published online1 May 2002Published inissue 1 January 1988ht…
The surface properties of wild-type and six mutant alpha-subunits of tryptophan synthase substituted at the same position, 49, which is buried in the interior, were measured by surface tension, foaming and emulsifying properties to correlate the surface properties with the stabilities. The conformational stabilities o…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTApplication of phosphine tellurides to the preparation of Group II-VI (2-16) semiconductor materialsM. L. Steigerwald and C. R. SprinkleCite this: Organometallics 1988, 7, 1, 245–246Publication Date (Print):January 1, 1988Publication History Published online1 May 2002Publish…
A single-crystal X-ray structure analysis has been performed for the complex bis(N-ethylpyridinium) bis[4,5-dimercapto-1,3-dithiole-2-thionato(2–)]cuprate(II). The crystals are monoclinic, space group C2/m, with Z= 4, a= 20.04(2), b= 14.56(2), c= 10.19(1)Å, and β= 109.2(1)°. Block-diagonal least-squares refinement, ba…
New series of ferroelectric liquid crystals with several bond moments near the chiral part have been prepared. The position and the orientation of those bond moments are found to strongly influence the magnitude of the spontaneous polarization in these ferroelectric liquid crystals, and the spontaneous polarization as…
Résumé.- L’auto-organisation des structures de dislocations, des lignes ou bandes de glissement, les instabilités plastiques macroscopiques, constituent, à différentes échelles d’observation, des manifestations typiques d’un comportement coopératif non linéaire. Cet aspect général est discuté sous l’angle des relation…
A new MnIII binuclear system with an oxo-bis(acetato) bridge and water co-ordinated to the Mn ions has been synthesized, crystallographically characterized, and its antiferromagnetic coupling measured (singlet–triplet gap 6·8 cm–1).
WAXD, SEM, DSC and TGA were used to investigate the crystallinity of polyaniline (PAn). The results show that the crystallization behaviors of undoped PAn depend on its polymerization conditions. The crystallinity of undoped PAn decreases with the increasing acidity from 0.001 to 7N in polymerization solution. Doped P…
Abstract Variations I–XVIII of a trimerlike cross‐linked collagen model peptide were synthesized and used to investigate the cooperation of different neighboring Gly‐X‐Y tripeptides. The carboxy‐terminal decapentapeptide of the tripe‐helical part of collagen type I was chosen as the starting point of sequentially modi…
Time-resolved laser-induced fluorescence (LIF) measurements have been carried out on the kinetics of CN(v= 0) and CN(v= 1) radicals with O2, NH3 and NO at temperatures between 294 and 761 K. The radicals were generated by pulsed laser photolysis of NCNO at 532 nm, and the decays of concentration were monitored using a…
For binary aqueous solvent mixtures the solvent composition in the first solvation sphere of Eu3+ has been determined at 25 °C by measuring the luminescence lifetime. In the systems water–acetone, water–acetonitrile and water–1,4-dioxane the first solvation sphere of Eu3+ is exclusively occupied by water molecules eve…
Abstract We review the effects of temperature on conductance and viscosity in the liquid state of vitreous ionic conductors and show how differences may be best understood by comparison of relaxation times for electrical and mechanical stresses acting on liquid or glassy states of the material. This leads to the defin…