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。
Isotropic Nd15(Fe1−xCox)77B8 ribbons are produced by conventional melt spinning. For moderate Co additions the coercivity HcI increases while the remanence Jr remains almost constant. Co contents above x=0.3 lead to decreasing HcI and Jr values. The beneficial effect of Co on coercivity is ascribed to the occurrence o…
A new liquid-crystal electro-optic modulating device similar to the surface-stabilized ferroelectric liquid-crystal device is described. It uses the same kind of ferroelectric chiral smectics and the same geometry as that device (thin sample in the ‘‘bookshelf ’’ layer arrangement) but instead of using a tilted smecti…
A 2D quasicrystal with an eightfold rotational axis has been found in rapidly solidified V-Ni-Si and Cr-Ni-Si alloys by means of transmission electron microscopy. The electron diffraction pattern taken along this axis shows no periodicity but a clear eightfold orientation symmetry. The corresponding high-resolution el…
The mechanisms controlling the growth rate of electrolyte crystals precipitating from aqueous solution may be classified in eight types.Most of these are associated with a specific kinetics -linear, parabolic or exponential, -and composites of these kinetics are also found.A linear kinetics is found when the crystal g…
An improved and efficient method has been developed for the purification of the tryptophan synthase alpha 2 beta 2 complex (EC 4.2.1.20) from Salmonella typhimurium containing a multicopy plasmid. Microcrystals prepared in 12% poly(ethylene glycol) 8000 containing 2.5 mM spermine are shown by scanning electron microsc…
Optical phonon spectra are investigated by infrared reflectivity measurements for La 1-x Sr x FeO 3 (x=0, 0.1, 0.25 and 0.4) and La 1-x Sr x CoO 3 (x=0, 0.02 and 0.1). Using the phonon parameters determined by Kramers-Kronig and oscillator analysis, the effective charges and the electron-phonon coupling constants are…
We have simulated the behaviour of a collection of particles interacting via the anisotropic Gay-Berne potential, using the molecular dynamics technique. The system is found to exhibit both an isotropic liquid and a nematic liquid crystal; the approximate temperature at which the transition between these phases occurs…
Abstract Blends of bisphenol‐A polycarbonate (PC) and polystyrene (PS) prepared by screw extrusion and solution casting have been investigated with weight fractions of PC in the blends varying from 0.95 to 0.05. From the measured glass transition temperatures ( T g ) and specific heat increments (Δ C p ) at the T g ,…
The adhesion of three microorganisms (Saccharomyces cerevisiae, Acetobacter aceti, and Moniliella pollinis) to different materials has been studied using various supports (glass, metals, plastics), some of which were treated by an Fe(III) solution. The surface properties of the cells were characterized by the zeta pot…
Thermal oxidation of Si is shown to be substantially affected by the implantation of Ge+ ions. A unique morphology develops during steam oxidation due to the rejection of Ge from the oxide at the growth interface. The Ge pile-up leads to the formation of a distinct layer of almost pure Ge between the oxide and the und…
A major site of pyridinoline cross-linking in bovine type IX collagen was traced to a tryptic peptide derived from one of the molecule's HMW chains. This peptide gave two amino acid sequences (in 2/1 ratio) consistent with it being a three-chained structure. The major sequence matched exactly that of the C-telopeptide…
We re-examine the charge longitudinal response, as measured in inelastic electron scattering, within the framework of a semi-classical RPA theory, utilizing a Skyrme force. The effects of the Hartree-Fock field are analysed. A comparison with an exact RPA calculation is presented.
Ag [C 3 H 6 NO 2 ] cristallise dans le systeme monoclinique avec le groupe d'espace P2 1 . Affinement de la structure jusqu'a 0,025. Les ions Ag I presentent une coordination digonale. Chaque ion Ag I est lie a un atome O (carboxylique) et a l'atome N (amine) de deux molecules d'alanine differentes pour former des cha…
Polycrystalline potassium samples have been plastically deformed under tension and the resulting effects on the phonon conductivity and phonon-drag thermopower have been investigated. The reduction of the lattice thermal conductivity ${\ensuremath{\lambda}}_{g}$ due to dislocations is much larger than can be explained…
Thin (<5 nm) air-oxidized Cr layers are deposited on the alumina output windows of radio-frequency klystron tubes to prevent electron multipactor by reducing the secondary electron emission yield of the alumina surface. The top several nanometers of these layers appear to be Cr2O3. To compare the measured surfa…
We have examined the angular distributions of medium-energy (500--1500 eV) elastically backscattered electrons from bulk Cu(001) and Ni(001) crystals and from pseudomorphic Cu on Ni(001). The observed diffraction features are largely governed by forward scattering of the outgoing electrons, and incoming beam scatterin…
An ${\mathrm{sp}}^{3}$ model for ZnS is constructed and validated by comparison with optical absorption and photoemission data. It is used to predict the atomic and electronic structure of three cleavage surfaces of ZnS, zinc blende (110), and wurtzite (101\ifmmode\bar\else\textasciimacron\fi{}0) and (112\ifmmode\bar\…
The properties of monolayer and multilayer deposits of ${\mathrm{N}}_{2}$ on graphite are calculated using a pattern optimization of the total lattice energy and a Monte Carlo procedure with continuously deformable periodic boundary conditions. It is confirmed that the monolayer ground state is a 2 \ensuremath{\surd}3…
The frequencies of several zone-center vibrational modes in graphite have been calculated from first principles, with results in very good agreement with experiment. By studying the effect of charge transfer and lattice-constant change on ${E}_{2g}$-mode frequencies, we find that the systematic stage dependences of bo…
The UV–visible spectrum of 200 nm thick films of poly(p-phenylene vinylene) (PPV) shows three absorption bands, with maxima at 6.12, 5.06, and 3.09 eV. The first two absorption bands are related to localized molecular states while the band at 3.08 eV has a more complicated character with a 1.5 eV bandwidth, a 2.49 eV…