Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
The nature of the holmium order in the reentrant superconductor (${T}_{c}=7.5 \mathrm{K}$) Ho${\mathrm{Ni}}_{2}$${\mathrm{B}}_{2}$C is revealed by neutron scattering. Upon cooling a transversely polarized oscillatory magnetic state is formed (${T}_{M}\ensuremath{\approx}8 \mathrm{K}$), characterized by a wave vector (…
We report on a scanning tunneling microscopy study demonstrating silicon mass transport and the resulting roughening of the surface during Sb deposition on Si(111). It is found that small amounts of Sb, which cause the Sb-induced d-(7×7) reconstruction, lead to Si island formation due to the replacement of Si atoms by…
Abstract The morphological changes induced to segmented polyurethane elastomers by varying the NCO/OH ratio during the second step of polymerization, while keeping constant the total hard‐segment content (∼ 30%), were studied by means of fourier transform infared spectroscopy (FTIR), differential scanning calorimetry…
Debye-H\"uckel theory for spheres of diameter $a$ with charges $^{\ifmmode\pm\else\textpm\fi{}}q$ is extended to general dimension $d$. Explicit results include Bjerrum association of +/- ions and the dipole-ionic solvation energy. For all $d>2$ a critical point terminates conducting-liquid-conducting-vapor coexist…
Ge-nanocrystal-embedded SiO2 glasses were prepared by a sol-gel process. The glasses synthesized through hydrolysis of Si(OC2H5)4 and GeCl4 were heated in the presence of hydrogen at 400–700 °C, in which Ge4+ ions were reduced to precipitate nanosized Ge crystals. Glasses doped with Ge nanocrystals of diameter of ∼5 n…
Abstract Small‐angle x‐ray scatting (SAXES) and transmission electron microscopy (TEM) have been applied to study polymer morphologies of CO 2 ,‐blown rigid polyurethane foam samples of varying isocyanate index. The results are consistent with an irregular (meso) phase segregated structure with phase boundaries showin…
We report lattice and electronical properties of BaTiO3:La powders and ceramics with 0<xLa<20 at.%. Dielectric measurements and x-ray scattering evidence a continuous decrease of the ferroelectric transition temperature when the La content is increased. For xLa=20 at.%, no dielectric maximum is found for temperatures…
Optically controlled planar orientation of liquid crystal molecules with polarized light is used to make phase gratings in liquid crystal media. The electro-optical properties of liquid crystal linear and chirped gratings are discussed.
We report on detailed neutron diffraction studies of both pinned and moving magnetic flux line lattices in $2H\ensuremath{-}\mathrm{Nb}{\mathrm{Se}}_{2}$. For field-cooled, pinned lattices, we are able to make a detailed quantitative comparison with the theory of Larkin and Ovchinnikov and find excellent agreement. In…
Using helium atom scattering Hulpke and L"udecke recently observed a giant phonon anomaly for the hydrogen covered W(110) and Mo(110) surfaces. An explanation which is able to account for this and other experiments is still lacking. Below we present density-functional theory calculations of the atomic and electronic s…
The crystal structure of beta-D-cellotetraose shows the same molecule packing as cellulose II, with two antiparallel molecules in the unit cell: For cellulose II, the orientation of the C6-O6 bonds has been described as gauche-trans and trans-gauche, respectively, for the two antiparallel molecules, which otherwise ha…
The ferroelectric polarization of perovskite oxides is much larger than implied by displacement of static ionic charges. We use an explicitly correlated scheme to investigate the phenomenon; charge transport is evaluated as a geometric quantum phase. Both covalence and electron-electron interaction enhance polarizatio…
The encapsulation of graphite-type carbon wires in the regular, 3-nanometer-wide hexagonal channels of the mesoporous host MCM-41 is reported. Acrylonitrile monomers are introduced through vapor or solution transfer and polymerized in the channels with external radical initiators. Pyrolysis of the intrachannel polyacr…
An exact result is calculated numerically for the dilute limiting, zero shear viscosity of bimodal suspensions of hard spheres. The required hydrodynamic functions are calculated from recent results for the resistivities of unequal spheres. Both the hydrodynamic and Brownian contributions to the Huggins coefficient ex…
In this paper we calculate how a pendant drop evolves at the end of a nozzle when the volume of the drop increases steadily with time. We find that the character of the evolution is strongly dependent on the growth rate of the drop and the radius of the nozzle. Typically we find that once the drop has become unstable,…
Extensive LDA and quasi-particle calculations have been performed on boron nitride (BN) single-wall and multi-wall nanotubes. Strain energies are found to be smaller for BN nanotubes than for carbon nanotubes of the same radius, owing to a buckling effect which stabilizes the BN tubular structure. For tubes larger tha…
A reciprocal space formulation of the Cluster Variation is used in order to extract effective pair interactions in alloys from experimental short-range order diffuse intensities. The method is applied to the analysis of the short range order contribution to the neutron diffuse scattering of a $Fe-19.5 {\%} Al$ single…
A fourth fatty acid condensing enzyme was isolated from Escherichia coli by its ability to restore elongating activity to a protein extract which had been treated with cerulenin, a condensing enzyme-specific inhibitor. The purified beta-ketoacyl-[acyl carrier protein] (ACP) synthase IV [3-oxoacyl-ACP synthase; acyl-AC…
The crystal structure of an allosteric chorismate mutase, the Thr-226-->Ile mutant, from yeast Saccharomyces cerevisiae has been determined to 2.2-A resolution by using the multiple isomorphous replacement method. Solvent-flattening and electron-density modification were applied for phase improvement. The current crys…
Two decay components of luminescence of oxygen-vacancy centres were observed in alkaline-earth fluoride and barium fluorohalide crystals at 17-300 K. We denoted them as slow and very slow components. Very slow components are observed in all crystals except for type II oxygen centres in BaFBr. Above 100-150 K the integ…