掺Ba对Bi系2212相超导电性的影响

研究了掺Ｂａ对Bi₂Sr_2-xBa_xCaCu₂O_y（０≤ｘ≤０．１５，０．３）单晶和多晶样品超导电性的影响，结果表明，有少量Ｂａ^２＋离子进入了超导相，且有固溶度极限．对于２２１２相单晶，ｃ轴参数和Ｔ_c均随Ｂａ含量增加而增加；对于慢冷多晶样品，掺Ｂａ可明显提高Ｔ_c；然而对于淬大多晶样品，Ｔ_c没有明显变化，用掺Ｂａ 关键词：     

Viscosity method for hierarchical fixed point and variational inequalities with applications

A viscosity method for a hierarchical fixed point solving variational inequality problems is presented. The method is used to solve variational inequalities, where the involved mappings are non-expansive. Solutions are sought in the set of the fixed points of another non-expansive mapping. As applications, we use the results to study problems of the monotone variational inequality, the convex programming, the hierarchical minimization, and the quadratic minimization over fixed point sets.     

Ab initio study of superoxide anion—water clusters O2 − (H2O)n=1-5

The structures, energies, Spectra, and charge transfer to solvent (CTTS) energies of the hydrated superoxide anion clusters have been investigated using both density functional calculations (DFT) with Becke-3-parameters employing Lee-Yang-Parr functionals (B3LYP) and second-order M?ller Plesset perturbation (MP2) calculations employing highly diffuse basis sets. Given the good agreement of our predicted results with the experimental spectra and enthalpy, it would be interesting if the CTTS energies could be experimentally determined.     

垃圾气化分析及其对中国实现碳中和与无废城市建设的贡献

气化是实现化学利用碳资源(尤其是煤)生产化学品和燃料的关键工艺.目前,全球拥有超过272套气化装置,主要应用于煤化工,尤其在中国.由于在一个化工厂通过技术集成达到工业规模的集中生产可实现减少二氧化碳排放并促进碳密集型行业的循环经济,如废物管理、化学和交通行业,因此,近年来全球对垃圾气化的兴趣日益浓厚,尤其是那些在煤气化...     

ANALYSIS OF PHOTOTRANSFORMATION INTERMEDIATES IN THE PATHWAY FROM THE RED-ABSORBING TO THE FAR-RED-ABSORBING FORM OF AVENA PHYTOCHROME BY A MULTICHANNEL TRANSIENT SPECTRUM ANALYZER

Phototransformation of the red-absorbing form of phytochrome (Pr) to the far-red-absorbing form (Pfr) was followed with a custom-built transient spectrum analyzer. Large phytochrome, which consisted of approximately 120000-dalton monomers, was immunopurified or conventionally purified from etiolated oat (Avena sativa L., cv. Garry) shoots. Phototransformation was initiated by exciting Pr with a 115-mJ, 600-ns half-width, 655-nm laser pulse. Absorption spectra were recorded on a microsecond time scale at predetermined times after the flash. It has been reported earlier that flash excitation of large oat Pr produces a transformation intermediate with maximum absorbance near 700 nm in a difference spectrum and that this intermediate decays by two kinetically distinct reactions. Difference spectra for these two reactions are indistinguishable. Both show bleaching centered at 690 nm with no detectable associated absorbance increase between 570 and 830 nm. Subsequent appearance of absorbance at 724 nm, which presumably but not necessarily represents the appearance of Pfr, had earlier been shown to occur by two kinetically distinct reactions for large oat phytochrome. Data presented here indicate in addition the occurrence of a third, slower reaction. Difference spectra for the two faster reactions are indistinguishable, both with maxima near 728 nm and minima near 650 nm. The difference spectrum for the slowest component, however, was qualitatively different exhibiting a maximum near 722 nm with no corresponding minimum. About 15-20% of the absorbance increase at 724 nm occurred by this slowest reaction, which exhibited a half-life of 3 s at 25°C and a Q₁₀ of 1.2 for immunopurified and 1.5 for conventionally purified phytochrome. The percentage occurring by this reaction was independent of temperature over the range studied (1-25dEC). For immunopurified phytochrome the enthalpy of activation, Gibbs free energy of activation, and entropy of activation of this slowest reaction were found to be about lOkJ-mol^-1, 75kJ.mol^-1, and -220 J.mol^-1 K^-1, respectively, and for conventionally purified phytochrome 25kJ.mol^-1, 75kJ.mol^-1and —170 J.mol^-1 K^-1, respectively. The thermodynamic characteristics of this reaction indicate that it may involve a significant ordering of the protein moiety as it transforms to Pfr.     

Novel Method of Preparation of Monolithic Columns for Fast Separation by γ-Ray Irradiation

A porous monolithic sol-gel column with the solution of methacryloxypropyltrimethoxysilane in toluene with an acid catalyst was prepared in the presence and absence of sodium dodecyl sulfate. In situ polymerization was carried out byγ-ray irradiation within the capillary. Theγ-radiation-initiated synthesis could generate radicals directly on the monomer avoiding use of any initiator. The chromatographic behavior of the capillary monolithic columns were studied in the modes of CEC, p-CEC and low pressure-driven separation, all the tests exhibited reversed-phase character. It provided a viable alternative to either thermally initiated or photo polymerization method for the preparation of monolithic columns.     

四碘化钛-三異丁基铝催化体系制备顺式-1,4-聚丁二烯——Ⅰ.催化剂的活性和聚合物的性质

研究了丁二烯在苯中有四碘化钛-三异丁基铝催化剂的存在下的聚合。发现这一催化体系的活性取决于Al/Ti比和聚合温度。对每一四碘化钛用量出现一具有最高活性的“临界Al/Ti此”;低于这一Al/Ti比,活性完全消失;高于这一Al/Ti比则活性逐渐降低(图2)。 增加Al/Ti可以减慢聚合速度而不影响最终转化率(图3);因此,可以利用Al/Ti来控制这一聚合反应以防止反应混合物的积热现象(图4)。 这一催化体系的优点是不论在任何条件下,包括催化剂组成(例如Al/Ti)和聚合条件(例如温度),聚合物都不合凝胶,而顺-1,4-结构含量总能在90％以上(表2)。 聚合物的分子量取决于两个主要因素:四碘化钛用量和聚合温度;增加四碘化钛用量和升高聚合温度都降低分子量(图5和图6)。Al/Ti对分子量的影响则不甚明显(图6)。 用这种催化剂制得的顺-1,4-聚丁二烯的分子量分布很窄(图7);因此,虽然这是一个非均相催化体系,它的活性中心可能比较单纯,大概不会含有多种活性中心。     

在铅板里发生的电子光子簇射

关于把电子光子簇射的实验与理论相比较的工作,还是非常的少。我们在用云雾室研究穿透簇射和星芒的过程中,也获得一些电子光子簇射的照片。从中选择了适合于研究条件的一部分,加以分析,与理论作比较。     

A Comparison of Residual-stress Measurements Using Blind-hole, Abrasive-jet and Trepan-ring Methods

This article describes the results of residual-stress measurements which were made on an artillery-projectile metal part to determine whether the state of the stress could be a factor in promoting a failure that had occurred during ballistic test firing. An additional objective of the work was to evaluate the suitability of several different methods for measuring residual stresses by the performance of these measurements on the same metal part.