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。
Abstract Due to the difference in reactivity between free isocyanates and uretdione rings, diisocyanate dimers can be used as blocked isocyanates. They offer the potential advantage that no volatile by‐products are formed. The toluene 2,4‐diisocyanate dimer contains one uretdione ring, formed by dimerization of two is…
Georgia kaolinite dehydroxylated at 950°C for 24 h, then leached with KOH at 90°C for 1 h, shows a well‐resolved 29 Si MAS NMR resonance at −77.5 ppm, within 2 ppm of the calculated position for Si incorporated in γ‐alumina spinel. From a knowledge of the total SiO 2 in the leached sample and its partitioning between…
Although past efforts in universities, government laboratories and industry have tried many materials in an attempt to find a mould suitable for casting titanium alloys, no ceramic mould that is completely resistant to titanium has been developed. Because much of this work was conducted more than 30 years ago and beca…
A preliminary survey of eight rivers and streams has revealed a distinctive epipsammic flora. The different water types support at least three distinctive associations of species. The separation of contaminant diatoms from other communities has been attempted, but there is still a problem, though it can be reduced whe…
Intershell spacings between carbon nanotubes ${\stackrel{^}{d}}_{002}$ ranging from 3.59 \AA{}A to 3.62 \AA{}A, with an uncertainty of \ifmmode\pm\else\textpm\fi{}0.06 \AA{}A, are deduced by using the in-plane C-C bonding length in the graphene hexagonal network as an internal calibration standard for the digital imag…
The diatom flora from two high altitude, tropical lakes is reported in this paper. These lakes (“Lago de la Luna” and “Lago del Sol”) lie within the crater of one of the major volcanoes in Central México: the Nevado de Toluca (4,620 m asl). Both had diluted, acidic water (pH ≤ 6, electrical conductivity (E.C.) ≤ 25 μS…
Abstract Pyrolysis coupled with GC/MS was used to study thermal degradation products of styrene—butadiene rubber (SBR). Introduction of samples, using the pyrolysis carrier gas through the split injection port, followed by sub-ambient focusing of pyrolysis products gave reproducible chromatograms. The styrene content…
Thermodynamic parameters for E. coli chorismate mutase are reported. In addition, site-directed mutagenesis studies provide a direct mechanistic link to yeast chorismate mutase, further indicating the importance of entropic restriction and hydrogen bonding in the enzymic catalysis of Claisen rearrangements.
Cu-doped Al-, Ti-, and Zr-pillared montmorillonites obtained by various procedures have been investigated with the aid of electron spin resonance (ESR). The major species present in pillared montmorillonites exchanged with copper at low pH are physisorbed square planar tetraaquo-complexes [Cu(H 2 O) 4 ] 2+ . Only at t…
Abstract The pressure dependence of the phonon modes in the layered semiconductor γ‐InSe has been investigated experimentally and theoretically for pressures up to 11 GPa. The mode Grüneisen parameters of all Raman‐active zone‐center phonons have been determined by Raman scattering under pressure. In addition, feature…
Corrosion properties of pulse-plated Zn-Ni alloy coating on a steel substrate were investigated using the neutral salt-spray test (ASTM B 117-81) and the potentiodynamic polarization technique (ASTM G 5-82). Performance of these alloy coatings with various Ni contents (up to 62 wt%) was compared to that of laboratory-…
The spin-wave dispersion relations in the ferromagnet MnSb, and the antiferromagnet CrSb, have been measured, by neutron inelastic scattering, along high-symmetry directions in reciprocal space, as a function of temperature. The effect of composition is discussed. The dispersion in CrSb is found to rise very steeply a…
Abstract DSC measurements around the glass transition in the homologous series of seven poly( n ‐alkylmethacrylate)s (alkyl=methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl) are presented. The step height Δ c p decreases linearly with the number of n ‐alkyl C‐atoms in the side chain. The usual glass step in the DSC…
Binary magnesium alloys containing chromium, manganese, or titanium were made using a physical vapour deposition technique. The corrosion resistance of the alloys was assessed in aqueous chloride solutions using total immersion tests in quiescent 600 mmol L−1 NaCI solutions. Alloying with manganese or titanium was fou…
The stimulated emission cross section σp for the 1060 nm transition of Nd3+ in lead borate and bismuth borate glasses has been determined from fluorescence measurements. The compositional dependence of σp, which has been evaluated using radiative transition probability, refractive index of the host glass, effective fl…
A (1012) twin boundary in deformed alpha-Ti has been observed by highresolution electron microscopy. The observations are in agreement with a model calculated using a many-body potential. A twinning dislocation is predicted by the topological theory and characterized directly in the experimental image with the circuit…
By using a 3-methoxy-4-hydroxy-benzaldehyde (MHBA) crystal as frequency doubler at room temperature, an efficient blue light output for near IR automatic tunable picosecond parametric laser is obtained, and blue-violet light output by frequency doubling of GaAlAs laser diode is also realized. A 404.5 nm light, with ou…
Inorganic materials can encapsulate organic dye molecules in a variety of ways. Those considered here are simple inorganic salts that have adsorbed, oriented, and overgrown dyes during growth from solution, which promise spectroscopic and photonic applications. The Figure shows KH 2 PO 4 crystals in which dyes carryin…
Abstract 1,4:3,6‐Dianhydrosorbitol (DAS) was used as chain extender in the preparation of new segmented polyurethane elastomers, based on polyoxytetramethylene or hydrogenated polybutadiene soft segments and 4,4′‐diphenylmethane diisocyanate (MDI). These materials exhibit a two‐phase microstructure, due to the thermod…
To address basic questions concerning proteins of the Sulfolobus acidocaldarius cell envelope, cell ghosts (empty cells consisting of cytoplasmic membrane complexed with the glycoprotein S-layer) were isolated and analyzed by standard biochemical methods. The constituent proteins included the two dissimilar subunits a…