Thermal analysis of transition metal and rare earth oxide system-gas interactions by a solid electrolyte-based coulometric technique

The oxidation-reduction behaviour of transition metal and rare earth oxide systems in oxygen potential controlled atmospheres was investigated by means of a solid electrolyte-based coulometric technique (SEC) in carrier gas mode to obtain information concerning the extent of oxygen stoichiometry, thep-T-x diagram of any mixed oxide phase, the kinetics of the oxygen exchange and the phase transitions.The direct coupling of SEC and electrical conductivity measurements provides further information about the relationship between oxygen deficiency and conductivity, especially as concerns the oxygen mobility and the transition from ionic to mixed ionic/electronic conductivity in any system.In the fluorite-type phases PrO_2–x, Ce_0.8Pr_0.2O_y–x and Ce_0.8Sr_0.08Pr_0.12O_y–x, the higher oxidation state of Pr is stabilized and the electrical conductivity increases in this sequence. The perovskite-type phase Sr_1–yCe_yFeO_3–x, shows transitions and a second phase reflected in the temperature-programmed spectrum of this substance. The electrical conductivity of Sr_0.9Ce_0.1FeO_3–x changes fromn-type top-type with increasing oxygen pressure.     

From second to first order transitions in a disordered quantum magnet

The cross sections and transverse spin asymmetries in the hard exclusive electroproduction of decuplet baryons are calculated in the large N(c) limit and found to be comparable to that of octet baryons. Large N(c) selection rules for the production amplitudes are derived, leading to new sensitive tests of the spin aspects of the QCD chiral dynamics both in the nonstrange and strange sectors. Importance of such studies for the reliable extraction of the pion form factor from pion electroproduction is explained.     

158 A Ge V p-Pb Pb-Pb碰撞中的单奇异和多奇异粒子产生

用描写相对论性核 核碰撞的LUCIAE模型及相应的MonteCarlo事例产生器分析了WA97最近发表的 1 5 8AGeVp Pb和Pb Pb碰撞中单奇异粒子 (Λ ,Λ)和多奇异粒子 (Ξ-,Ξ-,Ω-,Ω-)的多重数和横质量分布 .由于LUCIAE模型包含了弦碎裂微观过程中奇异夸克压低因子随碰撞体系的能量、中心度和质量的增大而增大 ,以及由它导致的相对论性核 核碰撞宏观过程中奇异粒子产额随上述三因素之增而增的物理机制 ;LUCIAE模型计算结果能较好描写WA97实验所揭示的相对论性核 核碰撞中奇异粒子产额随中心度之增而增和奇异粒子增强随奇异夸克数之增而增的实验事实 ,以及单奇异和多奇异粒子的横质量分布 .     

Synthesis,Crystal Structure and Selected Properties of Mono(dithiocarbamato)‐gold(I), AuS2CNH2

The title compound AuS₂CNH₂ was prepared from an aqueous solution by reaction of dicyanidoaurate [Au(CN)₂]^– with excess of ammoniumdithiocarbamate NH₄S₂CN H ₂ at pH ≈ 2. The compound crystallizes in the orthorhombic space group Cmma with a = 6.4597(2), b = 12.6556(3), and c = 5.3235(1) Å. The crystal structure comprises linear S–Au–S dumbbells forming unbranched zigzag chains in combination with the dithiocarbamate ligands. The three‐dimensional arrangement of the molecules is realized by aurophilic Au^I–Au^I and hydrogen bonding interactions, respectively. AuS₂CNH₂ presents orange luminescence due to a broad emission band between 12000 cm^–1 and 23000 cm^–1 (ν = 26316 cm^–1).     

Über Oxidsulfide mit Åkermanitstruktur CaLaGa3S6O,SrLaGa3S6O,La2ZnGa2S6O und Sr2ZnGe2S6O

On Oxidesulfides of Åkermanitetype-Structure CaLaGa₃S₆O, SrLaGa₃S₆O, La₂ZnGa₂S₆O, and Sr₂ZnGe₂S₆O The oxide sulfides were prepared for the first time (space group and lattice constants see “Inhaltsübersicht”). The atomic positions were refined from single crystal X-ray data for CaLaGa₃S₆O and La₂ZnGa₂S₆O. Problems concerning the metal distribution on the crystallographic positions are discussed by comparing interatomic distances. The ratio c/a of the new compounds is compared with that of isotypic compounds from literature.     

网络上两类物资联合最大流问题的极流特征

当网络上(诸如交通网络、通讯网络)有多种不同物资或信息同时分别从相应的发点输送到相应的收点,要求每条线路上各类物资或信息的输送量总和不超过线路的容量时,寻求所有物资的最大输送量的问题,就是所谓网络多种物资的最大流问题,这个问题在生产实际和理论上都有着重要的意义,1963年T.C.Hu提出了求两类物资联合最大流的标号方法,但是为了保证有限步达到最大流,要求边的容量是偶数。 本文是文献[3]的继续,用图论的语言描述了两类物资最大流问题极流的特征,并对标号方法作了一点修改,使得有限步得到最大流,或者在某一步得到极流后,保证以后的迭代是从极流到极流.这样因极流的个数是有限的,并且最大流总可以在极流上达到,从而保证了有限步内得到所要求的最大流,无须对边的容量作任何限制, 本文所提的算法是使图形特征很强的标号算法和线性规划的极点迭代结合起来,这就使得有可能把这种方法,推广到更大的一类问题中,例如,研究容量的改变对最大流量的影响。     

Neutron and X-ray investigations on the oxygen bonding in YBa2Cu3O7-x combined with physico-chemical methods

The occupancy of the oxygen lattice positions at different annealing conditions in YBa₂Cu₃O_(7–x) were determined by Rietveld refinements using neutron and X-ray diffraction data. The occupation density for the oxygen positions O1 to O4 were ascertained. The values of the oxygen content of the samples from this method were compared with those measured by thermoanalysis. The O1 and O4 oxygen atoms are exchangeable by thermal treatment. The oxygen in the planes is fixed and can not be removed by thermal treatment up to 935°C. The binding strength of O1 in the lattice is stronger than that of O4 atoms; this is demonstrated by a higher temperature of dissociation of the O1 atoms. The amount of the oxygen taken up is not exactly equal to the oxygen actually in the lattice positions. In the temperature region below 400°C adsorption and chemisorption processes are become dominant.     

分子束研究GaAs和InP与氯的激光化学反应动态学

本文采用CW超声分子束和时间分辨质谱技术,研究了在紫外和可见(355nm和560nm)脉冲激光辐照下GaAs(100)和InP(100)表面与氯的激光化学反应动态学。由质谱和飞行时间谱测得反应的主要产物为GaCl_x和InCl_x(x=1,2),研究了激光波长和能量密度对产物飞行时间谱的影响,首次发现提高入射Cl₂分子的平动能对上述激光诱导气-固相反应有明显的增强作用。     

A Study of Synthesis, Immobilization and Catalytic Capability of Metalloporphyrin

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