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。
Two models are proposed to solve the sodium nitrate structure near the order-disorder phase transition (Tc = 276 °C). The first model is built with the static disorder assumption between the two equilibrium positions of NO-3 ions. In this case, disorder is characterized by an order parameter : η. For the second model,…
Fifty-six of the more abundant estuarine epipelic diatoms are described from surface sediment samples collected from the upper basin of the Pettaquamscutt River, Rhode Island. Biraphid diatoms are the dominant primary producers on the muddy sediment under 2 to 7 m water. Three families are represented (Navicula-ceae,…
Description de la structure cristalline de Ba 2 Ca(B 3 O 6 ) 2 qui cristallise dans le groupe d'espace R3 avec a=7,165, c=17,680 A, Z=3. Relations structurales se rapprochant davantage de la forme β haute temperature que de la forme α basse temperature de Ba 13 ZO 4 . Composes isotypiques obtenus pour Cd, Mg, Co et Ni…
Precipitation of M23C6 and σ-phase during isothermal aging of δ/γ duplex stainless steels has been studied mainly by means of transmission electron microscope coupled with energy dispersive X-ray analyser. M23C6 particles form at both γ/γ and γ/δ boundaries. The particles are crystallo-graphically related to either on…
The crystallographic and magnetic properties of Tm 6 Fe 23 before and after hydrogen absorption were studied by means of X-ray diffraction, bulk magnetic measurements and 169 Tm and 57 Fe Mossbauer spectroscopy. The data were analysed in terms of a mean-field model. Coupling constants describing the magnetic interacti…
The study of the europium(III) ion + water + bromide system shows totally outer-sphere interactions between the anion and the ground-state 7F octa-(E8) and nona-(E9) hydrated europium species. An appropriate analysis of these interactions, involving the corresponding (E8B) and (E9B) outer-sphere bromocomplexes or any…
Reflection, absorption and emission spectra of InBr, InI and InBr 1- x I x mixed crystals have been measured at 2 K by using polarized light. In InBr, a prominent exciton peak is found at 2.48 eV for the polarization E // b , which is on the high energy side of the lowest direct exciton peak at 2.33 eV allowed for E /…
International audience
CSF levels of GABA were investigated in a group of Parkinson patients without drug treatment and a group of Parkinson patients under treatment with L-DOPA or anticholinergics. Probenecid results in an elevation of CSF GABA levels in healthy persons. The results indicate a significant decrease of GABA levels in CSF in…
Experimental values are reported for the distortion viscoelastic and elastic ratios for a homologous series of nematic Schiff's bases : APAPAm (m = 1-5, 9) and OHMBBA as a function of temperature. In the experiments the homodyne photoelectric self-beat technique was used to detect noise intensity spectra and to determ…
A solid solution of nickel in β -rhombohedral boron of composition NiB 48.5 has been investigated using X-ray single-crystal diffractometry. The space group is R [unk] m (No. 166) and the hexagonal unit cell dimensions a = 10.9615(5) Å and c = 23.8544(7) Å. The boron atoms occupy 16 atomic positions, of which two are…
Abstract Synthesis and growth of PbTe and (Pb, Sn)Te single crystals by the Bridgman method and by the Travelling Heater Method (THM) from Te‐rich solutions are described. It is to be seen from comparative investigations that seeded THM growth reproducibly provides oriented single‐crystalline ingots free of low‐angle…
Par photo-excitation a 307 nm d'atomes Fe dans H 2 en matrice de Xe a 12 K, insertion de Fe dans H-H et formation de FeH 2 . La reaction de photo-insertion Fe+H 2 →FeH 2 peut etre suivie a l'echelle microscopique par la photoreaction inverse a 440 nm FeH 2 →Fe+H 2 a 12 K selon un processus d'elimination reductive non…
Several crystals of kalsilite were synthesized and the structural refinement was carried out to elucidate the structural detail of the pure end-member of the KAlSiO4. The crystal is hexagonal, P63, with a=5,151(5) and c=8.690(8)Å. The structure was refined by the full-matrix least-squares method on the basis of counte…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTBiphenylene end-capped polyquinoline and polyimide prepolymers as matrix resins for high-use-temperature compositesJohn P. Droske, John K. Stille, and William B. AlstonCite this: Macromolecules 1984, 17, 1, 14–18Publication Date (Print):January 1, 1984Publication History Pub…
A cilia sublayer model of mucous transport in the lung is developed by considering a two-layer model of the fluid. Both the lower peri-ciliary layer and the upper mucous layer are modelled by Newtonian fluids. Cilia are allowed limited penetration into the more viscous upper layer during the effective stroke, otherwis…
Die ersten Monoarenkomplexe von Gallium(I) wurden aus Ga2X4 (X = Cl, Br), in Toluol suspendiert, und Hexamethylbenzol erhalten. In 1b sind C-1 und C-4 des Arenliganden zum GaI hin verschoben: 1b kann somit sowohl als π-Komplex als auch als nido-Cluster angesehen werden.
A variety of techniques involving electrochemical, hydrogen permeation and acoustic emission measurements have been used in studying the stress corrosion cracking of initially smooth and pre-cracked specimens of a maraging steel in different chloride-containing solutions. In solutions having pH's in excess of 2, crack…
Poly crystalline and single‐crystalline α‐alumina were reacted with a eutectic CaO‐Al 2 O 3 melt at 1530°C. A reaction zone develops in which a strongly textured CA 6 layer, as well as a CA 2 layer, forms, with a remaining layer of unreacted CaO‐AI 2 O 3 melt. Silica, an impurity in the α‐alumina, is rejected by the a…
Hardness and compressive strength, Young's modulus, bend strength, and fracture toughness were measured in wrought and commercially sintered T42 high-speed steel. After identical heat treatments, no significant differences were found between wrought and sintered materials in hardness (800–1010 HV50), Young's modulus (…