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。
Research News: Freely suspended thin film of smectic liquid crystalline materials can be described as two‐dimensinal fluids with a regular layer structure in the third dimention. By reducing the internal pressure in the set up shown in the figure the films can be transferred onto solid supports allowing their study, m…
Abstract X-ray diffraction was used to analyse the distribution of clay minerals in the <2 µ m fraction of the lutitic and marly facies from the centre of the Basque-Cantabrian Basin (Basque Arc), where the sedimentary section is 2000 to 10,000 m thick. Most of the deposits were laid down during the Cretaceous and…
Two non-first-order kinetic peaks at about 350 and 500 K appear in the thermoluminescence (TL) spectra of single-crystal and polycrystalline ${\mathrm{MgAl}}_{2}$${\mathrm{O}}_{4}$ irradiated with ionizing radiation at room temperature. Among others, emission from ${\mathrm{Cr}}^{3+}$ and ${\mathrm{Mn}}^{2+}$ ions are…
Silicon dioxide films deposited from the plasma‐enhanced chemical vapor deposition (PECVD) reaction of silane and nitrous oxide in the presence of helium were studied to determine the effects of temperature and radio frequency (RF) power on the deposition process. Increased RF power density yielded oxides which were s…
We study the interaction of disclinations in the presence of an applied magnetic or extensional flow field, which tends to align the director. Disclinations and inversion walls in the director field of nematic thermotropic liquid-crystal polymers are imaged at high resolution using the lamellar decoration technique of…
Abstract The thermal behaviour of sepiolite and palygorskite treated with pyridine (Py) was investigated by DTA, TG, DTG and EGA (by MS) under a flow of air and inert gases (N 2 or Ar). The thermal analysis showed that the organic base was adsorbed by the clays, penetrating into the clay pores and replacing zeolitic a…
Abstract A new family of addition curing polyimides were prepared that contained 4‐amino [2.2]‐paracyclophane as the endcap. An improved synthesis of the endcap 4‐amino‐[2.2] cyclophane was accomplished increasing the yield to 60% and simplifying the procedure. DSC and rheological analysis of endcapped polyimide oligo…
A new metastable liquid-crystalline phase BPS was observed in pure chiral compounds. The BPS is transformed reversibly from the supercooled BPI and is thermodynamically stable with respect to the BPI and metastable to the cholesteric phase. Rhombic single crystals of the BPS probably indicate a cubic lattice structure…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAn x-ray crystallographic and single-crystal EPR investigation of the cationic, iron-centered radical tricarbonylbis(triphenylphosphine)iron(I), {Fe(CO)3(PPh3)2+}. A theoretical examination of the structural preferences of five-coordinated seventeen-electron complexesJoseph…
A continuum damage mechanics description of elastic-brittle fracture provides an appropriate constitutive model for impact simulations involving ceramic, rock, or similar materials. For an orthotropically damaged solid, a complementary energy function may be derived from a mesomechanical description of three orthogona…
The essential feature of small, modular high-temperature reactors (HTRs) is the inherent limitation in maximum accident temperature to below 1600°C combined with the ability of coated particle fuel to retain all safety-relevant fission products under these conditions. To demonstrate this ability, spherical fuel elemen…
A new class of lipids, arsonolipids or rac-1,2-diacyloxypropyl-3-arsonic acids, have been synthesized by acylating tetrabutyl ammonium hydrogen rac-1,2-dihydroxypropyl-3-arsonate with myristic, palmitic and stearic anhydrides in the presence of pyridine. The yields are moderate to low due to decomposition of rac-1,2-d…
Abstract It was demonstrated in a previous investigation that both horizontal and vertical shifting is required to produce master curves for the relaxation moduli from elevated temperature data for polyethylene gas pipe materials. In this study, the shift functions obtained from these stress relaxation tests are appli…
We have studied electrically driven convective flow in thin, freely suspended films of smectic-A liquid crystal. Here we report measurements of the two-dimensional velocity field of this flow as the driving voltage is varied. Our results are well described by the first few terms of an appropriate mode expansion over a…
Molecular-dynamics simulations have been carried out on a ``soft-sphere'' model for binary alloys quenched into supercooled states. The main emphasis of this work is on the dynamic characterization of the glass transition. In the vicinity of the glass transition jump motions of atoms are dominant for the diffusion pro…
The effects of temperature cycling and heating rate on the release behavior of 85Kr have been studied for U02 pellets irradiated in a commercial BWR during 3 and 4 cycles (burn-up: 23 and 28GWd/t), by using a post irradiation annealing technique. In addition, characteristics of intergranular bubbles in base-irradiated…
Ferroelastic / ferroelectric phase transitions in Cd2Nb2O7 crystals have been analyzed by means of polarized light microscopy associated with electric characterization. The symmetry of the ferroelectric phase below T2 = 194 K is found to be orthorhombic mm2(pp) with the spontaneous polarization PS parallel to [001]cub…
We present a new algorithm for the design of phase-only gratings. In general, a successful grating design will shape the relative intensities of the diffracted orders while simultaneously maximizing the light contained in the orders of interest. This iterative algorithm achieves both of these goals. Solutions typicall…
A neutron-diffraction study has been carried out on KH2PO4 at 16.5kbars and 10K, close to the point at which the transition temperature, Tc, falls to OK at 17.1kbars. The results suggest that under these conditions, the H atoms are still disordered over two sites with a separation, δ, of 0.22(2)Å. Comparison with resu…
The first TeIII radical cation 1 occurs as monomer in its AsF6 salt. This was proved for 1-AsF6, obtained unexpectedly from the reaction of Te(N(SiMe3)2)2 with AgAsF6 in the form of black crystals. The blue metastable solutions in CH2Cl2 and CHCl3 display only one broad ESR peak, showing that the unpaired electron occ…