Materials Literature
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The cell parameters of deuterated gypsum have been extracted from Rietveld analysis of powder neutron diffraction data within the temperature range 4.2-320 K. The thermal expansion of gypsum is highly anisotropic along the b axis principally because of the effect of the D2.. .01 hydrogen bond. The high-temperature lim…
Prenyltransferases catalyze the consecutive condensation of isopentenyl diphosphate with allylic diphosphates to produce prenyl diphosphates whose chain lengths are absolutely determined by each enzyme. To investigate the mechanism of the consecutive reaction and the determination of the ultimate chain length, a rando…
A quantitative model for liquid phase sintering is developed based on the following ideas. During heating a liquid phase forms, which is easily mobile, wets the solid particles completely, dissolves solid atoms and provides an easy diffusion path for them. The solid density increases by particle rearrangement and by t…
Abstract Progress on the area of passivation of metallic materials by polyaniline is being presented. The redoxcatalytic reaction leading to the formation of a passivating oxide layer has been evaluated, and a reaction scheme is shown. Results of corrosion tests are described as well.
Structural, transport, and magnetic properties of ${\mathrm{Nd}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Ca}}_{\mathit{x}}$${\mathrm{MnO}}_{3}$ (0\ensuremath{\le}x\ensuremath{\le}1) have been studied to probe the consequence of strong lattice distortion and reduced double exchange. Charge ordering has been obse…
No abstract available.
Optoelectronic components require materials with large second‐order nonlinearities. Recently, various types of non‐classical chromophores have been developed, in the hope that they have improved physical properties for materials formation. The main research directions and latest developments reviewed here include mult…
Abstract The relationship between catalyst structure and enantioselectivity in the asymmetric epoxidation of unfunctionalized olefins by a series of chiral Mn(sa1en) complexes (1 – 10) was examined. The X‐ray structures of 5‐coordinate complexes 5, 8, of 6‐coordinate 9 ([6,6′= ‐ t Bu; 4,4 = ‐ t Bu] + ClO 4 − ), and 10…
Abstract A macroscopic energy balance model for crystalline swelling of 2:1 phyllosilicates is presented. Crystalline swelling for a static system is modeled by a balance among the potential energies of attraction, repulsion and resistance. The potential energy of attraction is due to both the electrostatic interactio…
During the processing of laminar ceramic, biaxial residual stresses can arise due to differential thermal contraction between unlike layers. A tensile stress can cause preexisting flaws to extend across the layer and into the adjacent layers and then tunnel until they meet either another crack or a free surface. A pre…
The effects of zero-point motion and the anharmonicity of the lattice vibrations of diamond have been explored theoretically in the context of a valence force model explicitly incorporating the isotopic composition. The predictions are tested in a study of the elastic moduli (${\mathit{c}}_{\mathit{ij}}$) deduced from…
Films of identically shaped, elongated, and parallel-oriented metal nanoparticles arranged in a regular pattern upon a transparent substrate were produced by use of electron-beam lithography. Because of the strong difference in the particles' polarizability components, the optical extinction spectra show strong dichro…
Epitaxial growth of diamond on iridium thin films was performed by direct-current plasma chemical vapor deposition with ion irradiation pretreatment of the substrate. Pyramidal epitaxial diamond particles with a number density of ∼10 8 cm -2 were grown on the iridium film. The epitaxial relation is written as (100) di…
The interaction of a long flexible polymer chain with mesoscopic particles of spherical or elongated cylindrical shape is investigated by field-theoretic methods using the polymer-magnet analogy. In the case that these particles are immersed in a dilute polymer solution and exhibit purely repulsive surfaces we study d…
Abstract The distribution of Ge‐O‐Ge and Si‐O‐Si bond angles α in amorphous germania and silica is re‐determined on the basis of diffraction experiments. The bond angle α joining adjacent tetrahedra is the central parameter of any continuous random network description (CRN) of these glasses. New high energy photon dif…
It is shown that SrBi2Ta2O9 (SBT) thin films can be made to exhibit significant polarization fatigue by electric-field cycling under broad-band, optical illumination. Photoinduced fatigue is also observed for Pb(Zr,Ti)O3 (PZT) thin-film capacitors with (La,Sr)CoO3 (LSCO) electrodes. These results demonstrate that both…
We have studied the sol-gel transition, the viscoelastic and the structural properties of networks constituted of semiflexible actin filaments cross-linked by \ensuremath{\alpha}-actinin. Cross-linking was regulated in a reversible way by varying the temperature through the association-dissociation equilibrium of the…
Morphology and structure of oxide films formed naturally on magnesium‐aluminum alloys by exposure to humid air and water have been investigated by use of ultramicrotomed cross sections by transmission electron microscopy and compared to the properties of films formed on pure magnesium. Similar to pure magnesium, the i…
Liquid crystal-polymer composites have been widely studied in the last ten years, both because of potential applications and to improve our understanding of the behavioural mechanisms involved. Although it cannot be exhaustive, this review describes recent advances in the field of liquid crystal-polymer composites. Th…