镍中氢与缺陷互作用的正电子寿命和多普勒展宽研究

采用正电子寿命和多普勒展宽技术研究了退火、回复及冷轧镍中氢与缺陷的互作用．结果表明：冷轧镍充氢后正电子平均寿命和多普勒展宽S参数上升，并且寿命谱的两成分拟合出现一个390ps的长寿命分量；而退火及回复镍充氢后正电子平均寿命和多普勒展宽S参数均不改变．因此认为冷轧镍充氢后正电子参数（平均寿命和S参数）的上升取决于氢和空位的互作用，与氢和位错的互作用无关；氢空位对也可以作为聚集空位的核心 关键词：     

染料增感过氧化酯体系引发的可见激光感光性高分子

由过氧化物3,3′,4,4′-四叔丁基过氧碳酰二苯甲酮和香豆素酮染料所组成的光引发体系对可见光敏感,致使感光树脂可以用氩离子激光曝光。感光树脂的敏度有赖于基体树脂,当用聚N-乙烯基-2-吡咯烷酮为基体树脂时,对波长488nm的氩离子激光可获得0-01mJ/cm²的高敏度。染料对过氧化物的敏化是由于电子从染料激发态转移到过氧化物而引起的。     

EXTRACTION OF RETINAL FROM Paramecium bursaria

Abstract— The ciliated protozoan Paramecium bursaria is photosensitive. Retinal, which is the chromophore of the visual pigments of many multicellular animals, was extracted from P. bursaria and identified by HPLC. The procedure of identification was based on the change in polarity achieved by reducing retinal with sodium borohydrate to form retinol. This method is useful for the detection of small amounts of retinal in cells containing large amounts of other substances with similar polarity. The presence of retinal in P. bursaria suggests that this ciliate may contain a photoreceptor pigment with retinal as the chromophore.     

Electron correlation effects in N2 and CO studied by X-ray scattering and CISD calculations

Total X-ray scattering intensities σ_ee(q) for N₂ and CO have been measured as a function of momentum transfer using the energy dispersive method. Novel procedures to extract accurate σ_ee(q), which eliminate effects of polarization, inelastic scattering, anomalous dispersion, and molecular vibration, have been proposed. A simplified theoretical treatment based on configuration interaction singles and doubles (CISD) calculations has been suggested. This procedure makes it possible to apply combined theoretical and experimental X-ray scattering studies to larger molecules. The inclusion of f and g functions is crucial, and the σ_ee(q) calculated with the cc-pVQZ[5s4p3d2f1g] basis set almost reproduces the data based on more elaborate MR-CISD calculations within the experimentally most relevant region of up to q ? 3 au. In contrast to experimental electron scattering data, the X-ray scattering intensities agree well with the computed results.     

Influences of chemical modifications on the mechanical strength of cellulose beads

Spherical cellulose beads having narrow particle-size distribution were prepared by the coagulation/regeneration method for small viscose droplets formed by centrifugal force in an acid bath. The influences of chemical modifications on mechanical strengths such as the hydraulic property and compressive strength were investigated, together with the effects on crystallinity, particle size and degree of swelling. Cross-linking with epichlorohydrin and substitution of hydroxyl groups in cellulose with diethylaminoethyl, carboxymethyl and cyanoethyl groups were studied. No remarkable differences were found in X-ray diffraction patterns for the cellulose beads after the chemical modification. The substitution promoted swelling of the beads and decreased the mechanical strength, probably by scission of intermolecular and/or intramolecular hydrogen bonds in cellulose. However, the cross-linking retarded the cellulose beads from swelling effectively. The beads were made significantly ha rder by the substitution, and this hardening effect competed with the softening effect of the swelling. Moreover, it was suggested that the simple compression test was useful for the prediction of the hydraulic property of the cellulose beads in the column operation. 0969--0239 © 1998 Blackie Academic & Professional     

Supramolecular Interaction of Keto-substituted Pyrroles

Several types of pyrrole derivatives bearing carbonyl groups were synthesized and their structures in the solid states were elucidated by single crystal X-ray analysis. In the case of α-ketopyrroles, the molecules exist as hydrogen bonding dimers between the pyrrole NH and carbonyl groups, while in the case of β-ketopyrrole derivatives, hydrogen bonding networks are formed. Both the α,β′-diketo-substituted pyrroles and their derivatives are suggested to be suitable for the construction of 1-D chain networks. Overall, the effects of substituents on the supramolecular interactions are discussed in detail.