Materials Literature
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The first polyoxomolybdates with an MoIINO instead of an MoIV O group are compounds 2 and 3. They were obtained by reductive nitrosylation of complex 1 with hydroxylamine in methanol. Pentamolybdate 2 is transformed into hexamolybdate 3 upon dissolution, for example in CH2Cl2. The structures of both title compounds ar…
By using the recently developed alternating-gradient magnetometer, that combines very high sensitivity and measurement rapidity, we have made observations of magnetic aftereffect in ferromagnetic films of a few atomic layers. These Co films have a perpendicular easy axis due to a large interface anisotropy and square…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanism of reactions of hydrogen peroxide and hydroperoxides with iron(III) porphyrins. Effects of hydroperoxide structure on kineticsTeddy G. Traylor and Joseph P. CicconeCite this: J. Am. Chem. Soc. 1989, 111, 22, 8413–8420Publication Date (Print):October 1, 1989Publicat…
Grinding induces resiual stresses and cracks at and near the surfaces of ceramic workpieces. The residual stresses in several ground ceramics are measured using the curvature method. Four‐point bend tests are conducted to measure the fracture strength of the ground specimens. A fracture mechanics analysis includes the…
The binding of analogues of the 7-methylguanosine-containing cap, m7GTP and m7GpppG, to eIF-4E from human erythrocytes as a function of pH, temperature, and ionic strength is described. From the pH-dependent binding of m7GTP and m7GpppG to eIF-4E, a new model describing the nature of the cap.eIF-4E interaction is prop…
The improvement of mechanical properties of Al 2 O 3 /SiC whisker composites has been studied with emphasis on the effects of the whisker content and of the hot‐pressing temperature. Mechanical properties such as fracture toughness and fracture strength increased with increasing whisker content up to 40 wt%. In the ca…
A method is described for determining an effective, depth dose consistent bremsstrahlung spectra for high-energy photon beams using depth dose curves measured in water. A simple, analytical model with three parameters together with the nominal accelerating potential is used to characterise the bremsstrahlung spectra.…
Films of various iron oxides including FeO, Fe3 O4 , and α-Fe2 O3 were formed on the α-Al2 O3 (0001) surface by a reactive vapor deposition method and characterized by x-ray diffraction and conversion electron Mössbauer spectroscopy (CEMS). The formation range for each phase was determined as a function of the substra…
The three-dimensional structure of a mutant of the aspartate aminotransferase from Escherichia coli, in which the active-site lysine has been substituted by alanine (K258A), has been determined at 2.8-A resolution by X-ray diffraction. The mutant enzyme contains pyridoxamine phosphate as cofactor. The structure is com…
Abstract Bismaleimide polymers offer a thermostability that fills in the gap between epoxies and high temperature polyimides. Bismaleimides of the new generation overcome traditional problems of brittleness and difficult processing. The property transpositions from these tougher, hot‐melt processable resins to the cor…
Abstract The venting and control strategies of a Magnesium Grignard formation reaction were assessed by theoretical predictions of the exotherm and the reaction rate, by simple laboratory measurements of the self heat rate, and by Leung's simplified equations and SAFIRE evaluations, based on DIERS methods. SAFIRE comp…
Abstract A viscous traction interfacial viscometer was constructed to study a mineral oil‐water‐emulsifier system. The effect on interfacial viscosity of the synthetic emulsifiers Span 80 and Pluronic L42 were investigated, along with the bioemulsifier produced by the yeast Torulopsis petrophilum. In the case of the s…
We report a high-resolution x-ray scattering study of the nematic--smectic-A transition around the tricritical point in mixtures of heptyloxypentylphenylthiobenzoate and octyloxycyanobiphenyl. Unusually large susceptibility and correlation length critical exponents are observed; this is explained as a clear example of…
The chirality-induced biaxiality is measured at the uniaxial-to-biaxial cholesteric phase transition of the lyotropic system including potassium laurate, decanol, ${\mathrm{H}}_{2}$O, and some chiral agent. The measurement of an induced biaxiality in a cholesteric uniaxial liquid crystal is reported. The corresponding…
The aecA and aecB loci map at 250 and 290 degrees, respectively, on the Bacillus subtilis chromosomal genetic map. The aecB locus has been proposed as the structural gene for aspartokinase II. From DNA sequence analyses and comparisons to the sequence of the aspartokinase II gene, it can be concluded that the structur…
Abstract Barbituric acid derivatives with electron donors at 5-position were synthesized and their second order nonlinear optical properties were investigated by electric field induced second harmonic generation (EFISH) method. It was found that barbituric acid units were strong acceptors and contributed to the large…
Abstract The mechanisms of palygorskite and sepiolite alteration to smectite under mild hydrothermal conditions were investigated by solid-state 27 Al and 29 Si magic-angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopy, X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). Palygorskit…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparation and x-ray structure of (tetramethyldibenzotetraaza[14]annulene)chromium dimer [(tmtaa)Cr]2. A multiply bonded complex of dichromium(II) without bridging ligandsJilles J. H. Edema, Sandro Gambarotta, Paul Van der Sluis, Wilberth J. J. Smeets, and Anthony L. SpekCi…
Abstract A homopolymer of L ‐lactic acid (LA), which was synthesized by direct polycondensation in the absence of a catalyst at 200°C, is crystalline, in contrast to the homopolymer of D , L ‐mandelic acid (MA) which is amorphous. Poly(LA‐ co ‐MA), obtained under the above conditions, is amorphous over a wide range of…
High-temperature deformation of A1-1 wt.% wg-1 wt. % Mn has been carried out in plane-strain compression at constant strain rate and temperature, and with abrupt changes in Zener-Hollomon parameter. Subgrain sizes and dislocation densities within subgrains have been measured and correlated with the roomtemperature pro…