Materials Literature
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The part played by molybdenum in the prevention of pitting corrosion of iron and steels in the presence of chloride ions can be explained using Raman spectroscopy. Here, molybdenum introduced as a molybdate in the electrolyte solution was particularly studied. Different polarization methods were used (potentiostatic p…
The structural model of tetragonal SeO 2 proposed by McCullough [JACS 59 (1937) 789] has been refined at 139 and 286 K. Space group P 4 2 / mbc , Z = 8, M w = 110.96, a = 8.3218(9), c = 5.0541(6) Å, V = 350.0(1) Å 3 at 139 K and a = 8.3622(7), c = 5.0612(5) Å, V = 353.9(1) Å 3 at 286 K. 349 and 635 unique reflections…
Abstract Cyclization of α,ω;‐dilithiopolyisoprenes has been achieved in hexane solution in the presence of tetrahydrofuran (15% in volume) at −40 to ‐ 50°C. Using as linking agent the non‐conjugated diene 1,2‐bis(isopropenyl‐4‐phenyl)‐ethane, macrocyclic polyisoprenes could be obtained with yields of at least 90%, eve…
This article concerns the problem of determining shapes of minimum stress concentration. Special emphasis is placed upon the mathematically precise formulation of these problems and upon the study of cases in which the optimum shape can be found in a highly explicit form. For all the cases discussed, a mathematical pr…
An electrical conductivity method was tested. The system of ammonium aluminum sulfate-water was used as a model system
The energy of the first plasmon loss peak has been determined for the ~-Zr hydride phase in pure Zr. The peak energy is sufficiently different from that of the 03B4-hydride to permit EELS "fingerprinting" with ease using a parallel EELS system, but with greater difficulty using serial EELS, because of drift associated…
ヨウ素化合物は炭素-ヨウ素結合の解離エネルギーが低いためラジカル的に活性で, ラジカル重合反応の過程では連鎖移動反応が関与する結果, ラジカル的連鎖再賦活化機構によるラジカルリビング重合の可能となることを見いだした. これを『ヨウ素移動重合』と称したが, 基本的に次のように総括することができる. 1) 重合系のポリマー分子数は系内に添加するヨウ素化合物分子数で決まる. 2) 分子量分布が狭いものを含め, 自由に調整できる. 3) ブロックポリマーの合成を含む遂次連鎖成長が可能である. 4) 分子末端を占めるヨウ素は反応性に富み, 種々のポリマーのテレキリックな架橋や末端反応性高分子の合成に利用できる. 5) 非対称モノマーでは付加…
Ceria, zirconia and zinc oxide have been successfully prepared by the thermal decomposition of the respective soluble cerium, zirconium and zinc salts in decan-1-ol, undecan-1-ol and ethane-1,2-diol. Only those metal salts whose (solid phase) decomposition temperature was less than or equal to the reflux temperature o…
The structures of the intercalates MgxTiS2–c(0 < x < 0.25), prepared by chemical means, have been refined using high-resolution X-ray powder diffraction. The solid-solution adopts a structure derived from that of a spinel, with space group Fd3m. Magnesium exclusively occupies the octahedral 16c sites within the cubic…
The paper describes a laboratory method used for determining the partial solubility parameters of five METHOCEL* and six ETHOCEL* cellulose ether products. A simple computer spreadsheet has also been devised to calculate the partial solubility parameters from the laboratory data. These new laboratory derived values ex…
An instrumented mannequin has been constructed for testing the thermal protective qualities of garments when subjected to short duration flash fires. To measure the rate of heat transfer to the mannequin surface 110 skin simulant sensors are used. The flash fires are produced with propane diffusion flames. A computer…
Diamond has been synthesized from cyclic hydrocarbons under high pressures between 6 to 9GPa and high temperatures ranging from 710 to 1290°C. The result offers a clue to the genesis of diamond in the deep interior of the earth.
We describe the synthesis and crystallisation by means of chemical vapour transport reactions of TiPO 4 and VPO 4 . TiPO 4 ( a = 5.2985(5) Å, b = 7.911(1) Å, c = 6.3473(5) Å) and VPO 4 ( a = 5.2316(5) Å, b = 7.7738(7) Å, c = 6.2847(5) Å) adopt the crystal structure of chromiumvanadate CrVO 4 ( Cmcm , Z = 4). The resul…
Abstract The mechanical properties of polymeric materials are of considerable importance to their engineering applications. Apart from the chemical structure and the thermal history, molecular orientation has a major influence on the mechanical properties of a polymer. The increased need for more detailed data and a b…
The preparation, X-ray crystal structures, conductivity and optical properties of the salts, [ttf]3[W6O19]1, [ttf]3[Mo6O19]2(ttf = tetrathiafulvalene) and [tmtsf]3[W6O19]·2dmf 3(tmtsf = tetramethyltetraselenafulvalene) are reported. Crystal data: 1, triclinic, space group P, a= 9.965(3), b= 10.503(3), c= 10.634(3)Å, α…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCoordination of 4,7-bis(2-hydroxybenzyl)-1-oxa-4,7-diazacyclononane (LH2) with manganese(II) and -(III) and zinc(II). Crystal structure of [(LH)2Zn2(.mu.-OH)](PF6).cntdot.0.5CH3OHClaus Flassbeck, Karl Wieghardt, Eckhard Bill, Christian Butzlaff, Alfred X. Trautwein, Bernhard…
FTIR spectra are reported of methanol adsorbed at 295 K on ZnO/SiO2, on reduced Cu/ZnO/SiO2 and on Cu/ZnO/SiO2 which had been preoxidised by exposure to nitrous oxide. Methanol on ZnO/SiO2 gave methoxy species on ZnO and SiO, in addition to both strongly and weakly physisorbed methanol on SiO2. The corresponding adsor…
We provide evidence for the existence of p → p-like transitions at the silicon L2,3-edges of common silicates. This arises due to the local, tetrahedral potential at the silicon site imposed by the nearest neighbour atoms leading to a loss of inversion symmetry. In order to successfully describe the resultant electron…
Indane-1,2,3-trione 1 is conveniently prepared in quantitative yield by the azeotropic drying of ninhydrin 2 using chlorobenzene as solvent. The central CO group of the trione is extremely electrophilic and ene addition occurs at this site with a wide range of alkenes and with terminal alkynes in aprotic solvents at m…
An autoinhibitor produced by Skeletonema costatum was extracted with ethyl acetate from the cultured medium. The extract dissolved in diluted aqueous NaOH was gel-filtered on Sephadex G-15 with water. The fractions which inhibited the growth of S. costatum were extracted with ethyl acetate, and the extracts were separ…