Solid oxide solutions as catalysts —A comparison with supported Pt

The hydroformylation of olefins with the water soluble complex HRh(CO) [P(m-C₆H₄SO₃Na)₃]₃ (1) is dependent on the solubility of the olefins in the aqueous phase. In contrast, when the aqueous solution of1 is immobilized on a high surface area silica support the effects of the size of the olefins diminish. The immobilized catalyst1 on silica shows significant water loss but not rhodium leaching. It is proposed that the hydrophilic support holds the water soluble phosphines by hydrogen bonding of the hydrated sodium-sulphonate groups to the surface.     

Sex pheromone of aPlanotortrix excessana sibling species and reinvestigation of related species

The sex pheromone of aPlanotortrix excessana sibling species was investigated. Females were found to produce eight potential pheromone components: dodecyl acetate, tetradecyl acetate (14OAc). (Z)-5-tetradecenyl acetate (Z5-14OAc), (Z)-7-tetradecenyl acetate (Z7-14OAc), (Z)-9-tetradecenyl acetate, hexadecyl acetate, (Z)-7-hexadecenyl acetate, and (Z)-9-hexadecenyl acetate. When these compounds were bioassayed using field-trapping and wind-tunnel techniques, only 14OAc,Z5-14OAc, andZ7-14OAc were found to be behaviorally active. The sex pheromone glands of females of other species including,Planotortrix MBS,Planotortrix M,P. notophaea, Ctenopseustis servana, and aC. obliquana sibling species, were also found to containZ5-14OAc orZ7-14OAc, singly or in combination. In the case ofPlanotortrix M, the addition ofZ7-14OAc to the previously identified sex pheromone blend ofZ5-14OAc and 14OAc was found to increase trap captures of male moths of this species. Thus in these New Zealand species (and in some Australian species),Z5-14OAc andZ7-14OAc appear to be utilized in combination in pheromonal communication just as (Z)-11-tetradecenyl acetate and (E)-11-tetradecenyl acetate are used by many species of Holarctic Tortricidae in the tribe Archipini.Lepidoptera: Tortricidae: Tortricinae.     

Surface copper enrichment by reduction of copper chromite catalyst employed for carbon monoxide oxidation

The effect of prereduction on CO oxidation activity of unsupported copper-chromite oxide catalysts was examined. Results were found to be in good agreement with two mechanisms for a surface copper enrichment due to CO prereduction which produced an activity increase in the copper-chromite catalyst.     

The hydrogenation of toluene over nickel loaded Y zeolites

The catalytic activities of a range of hydrogen reduced nickel Y zeolites for the hydrogenation of toluene were measured and correlated with the following catalytic parameters: reaction temperature; reaction time; coke deposition. The role of the alkali metal co-cation (Li⁺, Na⁺, K⁺, Rb⁺ or Cs⁺) in influencing the overall hydrogenation activity of the supported nickel metal was probed. The effect of poisoning the surface Bronsted acidity by the adsorption of ammonia is discussed. For comparative purposes, data on the hydrogenation of benzene over the same catalysts are included.     

Modeling the intact form of the {alpha}1-proteinase inhibitor

The structure of the intact form of the serpin ₁-proteinaseinhibitor has been modeled based on the assumption that thecentral strand s4A of the six-stranded ß-sheet A ofthe cleaved inhibitor is not incorporated into the sheet ofintact ₁-proteinase inhibitor. This strand was removed fromits position in the center of the sheet by suitable rotationsabout the backbone dihedrals of Lys343 using molecular graphics.The resulting structure was then annealed using molecular dynamics(MD) while applying progressive distance restraints to the reactivepeptide bond (Met358-Ser359) for 50 ps. During this time, thedisrupted ß-sheet reformed to create a five-strandedß-sheet with strands 3 and 5 in a parallel arrangement.This change and accompanying structural rearrangements are largelyconfirmed by the X-ray structure of plakalbumin, whose structurereflects the overall structure of intact serpins. The successfulmodeling experiment demonstrates the utility of MD for makinggross structural predictions based on related structures. Thebinding loop of the intact form is modeled to allow dockingwith serine proteinases, in particular thrombin, which mosthighly constrains the possible conformations of the bindingloop.     

五类电缆的工艺设计与制造

介绍了局域网用五类电缆的性能要求、工艺设计及制造方法,并指出了五类电缆的市场前景。     

Zn-5％Al-RE合金镀层钢丝表面质量分析

分析了Ｚｎ-５％Ａｌ-ＲＥ合金镀层钢丝表面不平整的原因，并提出了应采取的措施。     

Growth and dielectric properties of Ta_2O_5 single crystals grown by laser heated pedestal growth technique

Ta2O5 single crystals have been grown by the laser heated pedestal growth (LHPG) technique up to several centimeters length with diameter of 1.1 mm. The crystal, characterized by X-ray diffraction, dielectric measurement, and thermal expansion analysis, has Htri-Ta2O5 symmetry. Dielectric permittivity, loss tangent along [001] and [110] direction were investigated over the temperature range from -80 ℃ to 100 ℃. Large dielectric anisotropy in Ta2O5 single crystal was observed. At room temperature, the dielectric permittivities (1 MHz) along [001] and [110] are 33.2 and 231.9, respectively. The reason of dielectric enhancement in Ta2O5 crystal grown by LHPG was also discussed.     

Isolation, DNA sequence and regulation of a new cell division cycle gene from the yeast Saccharomyces cerevisiae

A new complementation group of temperature-sensitive mutants of the yeast Saccharomyces cerevisiae (ts26-1 and ts26-2) has been isolated and characterized. This mutation maps at 40.7 cM from arg8 and 48.9 cM from arg1 on the left arm of chromosome XV of yeast, providing that it is a newly identified gene. The dumbbell-shape terminal morphology of the mutant cells at the restrictive temperatures is a characteristic of mutants defective in DNA replication. To study the defect of macromolecule synthesis in the mutant cells, DNA, RNA, and protein synthesis were measured at both permissive and restrictive temperatures. The data suggest that the primary defect of this mutation is at the initiation step of DNA synthesis. The gene has been cloned from an S. cerevisiae genomic library by rescue of the conditional lethality of the mutants. It is present as a single copy in the haploid genome. DNA-RNA hybridization of the gene has identified 1 kb RNA, which is under cell-division-cycle control. DNA sequence analysis of the gene has identified an open reading frame capable of encoding a protein of molecular weight 25,055 (214 amino acids).     

Effects of processing variables on the Y2BaCuO5 size and magnetic properties of melt-processed YBa2Cu3Ox

Samples of YBa₂Cu₃O_x (123) with excess Y₂BaCuO₅ (211) in the molar ratio of 5:1 ( 123/211) were processed using the “solid liquid melt growth” (SLMG) technique. The effect of hold time above the peritectic on the magnetic properties was examined. Extended hold times above the peritectic during processing degrade the magnetic properties of SLMG processed 123. In SLMG 123, the very fine (>100 nm) 211 particles produced by this processing route are the primarymagnetic flux pinners. Extended hold periods reduce the number and/or coarsen the average size of these fine precipitates, resulting in a reduced magnetization. These results were compared to undoped Y123 processed by the more traditional melt texture growth (MTG). In MTG processing, extended hold times above the peritectic are found to result in improved magnetic behavior because of increased defect densities.