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。
A molecular theory is presented for the dynamics of small-molecule nematic liquid crystals in shear flow. The flow-alignment angle is predicted to depend on the aspect ratio of the liquid crystal molecules, as well as the second and fourth moments, P2 and P4 of the distribution of molecules about the nematic director.…
The Stokes–Einstein and Stokes–Einstein–Debye relations hold well in nonsupercooled liquids; however, sizeable deviations from the former appear in supercooled liquids, leading to a ‘‘decoupling’’ of translational diffusion from viscosity and reorientational relaxation. We attribute this breakdown and this ‘‘decouplin…
The magnetostrictive stress for a ${\mathrm{Ho}}_{6}/{Y}_{6}$ superlattice has been determined at low temperatures by means of a capacitive cantilever technique. The magnetostrictive stress responsible for the basal plane distortion is found to be strongly enhanced with respect to bulk holmium. An explanation accounti…
Thin nanoporous Si layers were formed on n-Si(100) in 0.1 M NH4F electrolyte and investigated with field emission scanning electron microscopy and photoluminescence (PL). The microstructure of the electrochemically prepared Si surfaces depended strongly on the pH of the electrolyte. A pebblelike surface structure was…
In this Letter we establish the phase diagram of $(\mathrm{TMTSF}{)}_{2}$ ${\mathrm{ClO}}_{4}$ to 30 T and above 0.5 K by transport and magnetization measurements. The high field region is bounded above by a second order transition from metallic to field induced spin density wave state at 5.5 K. Completely contained i…
Diamond films and islands grown by chemical vapor deposition were implanted with boron, sodium, and carbon ions at doses of 1014–1015/cm2. This structural modification at the subsurface resulted in a significant reduction of the electric field required for electron emission. The threshold field for producing a current…
Biaxial stress and strain in (100) and (111) oriented grains have been measured as a function of annealing temperature for a Cu film on an oxidized Si substrate which exhibits abnormal (100) grain growth. The observed behavior indicates isostrain averaging, which is consistent with grain growth that is controlled by s…
We determined the phase diagram of a binary hard-sphere dispersion with size ratio 9.3. Phase separation into a fluid and a crystal of large spheres is observed. The fluid-solid binodal is determined by measurements of compositions of coexisting phases. The results agree qualitatively with recent theories, although th…
A theory for the nematic-isotropic (N-I) phase transition of prolate uniaxial molecules with longitudinal dipole moments is presented. The theory is based on the variational cluster expansion, truncated after the two-molecule term, and is implemented for polar hard spherocylinders with and without attractions, and for…
The effective diffusion coefficient, D(e), and the distribution constant, K(i), for selected mono- and disaccharides and organic acids were determined in homogeneous calcium-alginate gel with and without entrapped bacteria. Results were obtained from transient concentration changes in well-stirred solutions of limited…
The spectral dependencies of the optical rotatory power (ORP) and Verdet coefficient (V) of undoped Bi<SUB>12</SUB>GeO<SUB>20</SUB> (BGO), Bi<SUB>12</SUB>SiO<SUB>20</SUB> (BSO) and Bi<SUB>12</SUB>TiO<SUB>20</SUB> (BTO), and doped with V, Fe and Cr BSO crystals are studied. It is established that Cr and Fe strongly cha…
The lateral fixing of calamitic mesogens through hydrogen bonding of facial amphiphiles is a novel way of generating smectic materials with a broad mesomorphic region. Compound 1 is an example of this amphiphile and represents a new type of liquid-crystalline carbohydrate. R = OC10H21.
Highly selective aerobic hydroxylation of tertiary carbon centers in alkanes is catalyzed by the title polyoxometalate under mild reaction conditions [Eq. (a)]. This is of great significance, in particular in the search for ways to activate molecular oxygen in the oxidation of hydrocarbons.
Bleomycin hydrolase is a cysteine protease that hydrolyzes the anticancer drug bleomycin. The homolog in yeast, Gal6, has recently been identified and found to bind DNA and to act as a repressor in the Gal4 regulatory system. The crystal structure of Gal6 at 2.2 A resolution reveals a hexameric structure with a promin…
The successful synthesis of pure boron nitride (BN) nanotubes is reported here. Multi-walled tubes with inner diameters on the order of 1 to 3 nanometers and with lengths up to 200 nanometers were produced in a carbon-free plasma discharge between a BN-packed tungsten rod and a cooled copper electrode. Electron energy…
Lattice images as obtained by high-resolution electron microscopy are used to quantify strain and strain profiles in semiconductor layer structures. Inherent parts of the analysis are the definition of spatial resolution and detection limit on the basis of a quantification of noise. As an application the tetragonal st…
Abstract Preparation of porous carbons from phase‐inversion membranes was investigated as a control method of pore structure in carbon materials. The structure in carbon films was estimated by means of electron microscopy, mercury porosimetry, and gas‐adsorption methods. When phase‐inversion membranes of Kapton‐type p…
An experimental study of the temperature and frequency dependence (in the audio and rf and microwave regions) of the conductivity of ${\mathrm{H}}_{3}$${\mathrm{PO}}_{4}$-doped polyaniline samples is presented. The dopant concentration of the samples varies between 0.09M and 3.60M. For all the samples studied, the tem…
Persistent spectral hole-burning phenomenon in CuBr quantum dots embedded in glass was observed. The spectral hole and the sideband holes were made together with the redshift of the absorption spectrum in proportion to the logarithm of the laser fluence and were preserved for more than 8 h at 2 K. They were erasable b…
Abstract The determination of viscoelastic property variation in short fiber‐reinforced composites, as a function of strain, temperature, and frequency, constitutes a useful tool when the existence or the strength of matrix–fiber interfaces are to be examined. In this work, these properties are studied in thermoplasti…