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。
Alpha uranium dicarbide disks coated with pyrolytic carbon migrate, relative to the carbon, up a temperature gradient, leaving behind a layer of rejected graphite. A model for the migration process based on solution of carbon at the hot UC 2 ‐C interface, transport across the UC 2 phase by thermal diffusion, and rejec…
The dehydrobromination of 3-bromo-6,6-dimethylbicyclo[3,1,1]heptan-2-one has been studied. Treatment with lithium bromide and lithium carbonate in dimethyl sulphoxide gave 6,6-dimethylnorpin-3-en-2-one (apoverbenone) in good yield. From (–)-pin-2(10)-ene, optical purity 91%, we obtained (+)-apoverbenone, [α]D+ 319°(c…
Coproporphyrin-I has been synthesised by modifications of Fischer's original methods; Coproporphyrin-II has been synthesised by three methods including a variant of the MacDonald method, involving self-condensation of a 5-formylpyrromethane-5′-carboxylic acid. Coproporphyrins-III and -IV and a related porphyrin tricar…
Cultures of blue-green algae of 44 soil samples and 40 samples of naturally growing ones, collected from highly saline soils, moderately saline soils and reclaimed saline soils, were studied in relation to the soil type. It was found that most of the species belonging to Chroococcales, Oscillatoriaceae, Nostoc, Tolypo…
Using digital methods, electric fields and paraxial electron trajectories in the two-tube electrostatic lens have been calculated, and the first-order (Gaussian) focal properties accurate to at least 0.1% were obtained for voltage ratios from 1.5 to 50. The results are presented in the form of P-Q (object-image positi…
Abstract The discovery that C-nitrosoanilines react with olefins to give p -phenylenediamines has made possible the synthesis of powerful antioxidants from a wide range of naturally occurring and synthetic unsaturated compounds. Simple alkenes, vegetable oils, and factices may be converted to antidegradants whose beha…
Abstract By means of x‐ray fiber diffraction, it has been found that xylan diacetate crystallizes with two chains or four residues in a monoclinic cell (space group P 2 1 ): a = 7.64, b = 12.44, c (fiber axis) = 10.31 Å, and γ = 85°. Pairs of residues are related by a twofold screw axis in the c direction. Based on th…
Aetioporphyrin-I (1a) is obtained in 50–60% yield by heating 5-bromo-3,4′-diethyl-3′,4,5′-trimethylpyrromethene perbromide (4a) under reflux in formic acid, surpassing the yields from the established syntheses using the less accessible 5-bromo-5′-bromomethylpyrromethene hydrobromides (2a, b). The 5-bromo-5′-methylpyrr…
Abstract Calcite crystals are grown under pure conditions by the method of counterdiffusion of calcium and carbonate ions in water. An extension of the diffusion method is used making possible the crystallization of calcite in a medium containing calcium or carbonate ions in excess of their stoichiometric amounts in c…
Abstract Products from the thermal decomposition of four polyurethane foams heated to temperatures in the range 220 to 400 °C, in atmospheres of nitrogen, of 6% oxygen in nitrogen and of air were examined for some of the anticipated toxic materials. When phosphorus‐containing inhibitors were added to or chemically inc…
The physical and electrical properties of barium titanate films approximately 1 μm thick, prepared by rf sputtering onto silicon substrates in both pure argon and 95% argon–5% oxygen glow discharges were investigated. The argon-oxygen mixture was used to minimize oxygen deficiencies in the films resulting from the pos…
(Uploaded by Plazi from the Biodiversity Heritage Library) No abstract provided.
Metakaolinite, or metakaolinite with added silica, has been treated with potassium hydroxide solutions to yield six zeolites and the two felspathoids kaliophilite and kalsilite. Among the zeolites K–F, K–M (near-phillipsite), and K–G (near-chabazites) were abundantly and consistently formed. The properties of these ze…
For many years, stannous chloride solutions have been used to prepare surfaces so that they would catalyze deposition from electroless plating solutions. This paper discusses the colloid and solution chemistry of such baths, including the colloid formation, size mediation, and aging processes. The colloid is shown to…
Abstract The results of characterization of the natural rubber vulcanizates are consistent with the results of characterization of the sulfidic products from 2-methylpent-2-ene. In both the model olefin system and the rubber system the initially formed crosslinks are polysulfidic but these are subsequently reduced to…
Abstract Calcium fluoride formed during a 1‐min extraction of calcite (50‐2 µm) with the Bray P‐1 reagent (0.03 M NH 4 F/0.025 N HCl) sorbed added P. Because of the problem in identifying minor components of a whole soil matrix by X‐ray diffraction analysis, it was frequently difficult to positively identify CaF 2 in…
Abstract The cure behavior of SBR and NR compounds was examined using the Monsanto Rheometer. The three cure parameters—induction period ( t d ), rate of crosslinking reaction ( k 2 ) and maximum increase in torque (Δ L )—were derived from the Rheometer torque curves. The data so obtained were used to calculate Westli…
The paramagnetic resonance spectrum of single crystals of RhCl3(PEt2Ph)3 doped with osmium has been measured at 77 K. No hyperfine structure is resolved and the g-tensor has principal values 3.32, 1.44 and 0.32. These values are analyzed using an extended form of the standard theory for low-spin d5, including configur…
A system has been devised for preparing permanent quantitative phytoplankton slides using sedimentation techniques. These slides can then be used with a conventional microscope. A three‐part settling chamber allows separation of the supernatant from the settled material. Water‐soluble mounting medium added to the samp…
Tensile tests at 300°C and structural examination have been carried out on specimens machined from annealed and cold-worked Zircaloy-4 fuel sheathing which had been neutron irradiated at 290°C. The stress-strain behaviour during testing at 300°C has been related to the microstructures observed by transmission electron…