Thermoanalytische Charakterisierung Strahlengehärteter Polymerfilme

Thermo-oxidative and thermo-mechanical stabilities of radiation-cured acrylates and epoxides were examined by TG, DMA and DSC.The polymeric trifunctional acrylates PETIA, TMPTA and THEIC displayed the highest temperatures of onset of degradation. The high crosslinking density of the films resulted in an almost temperature-independent complex E-modulus, as measured by DMA. With increasing degree of ethoxylation or propoxylation of the monomers, decreases in thermal stability and strength were found. For difunctional polymeric acrylates and epoxides, the glass transition temperature was measured.The average degree of curing of UV-cured epoxy films can be determined from the temperature of the maximum in the loss modulus (E_max.This revised version was published online in November 2005 with corrections to the Cover Date.     

纳米氧化锆的物相与尺寸效应

用溶胶凝胶法制得ＺｒＯ２粉体。通过控制晶体尺寸得到了室温下稳定的立方相、四方相和单斜相。用Ｘ射线衍射（ＸＲＤ）、透射电镜（ＴＥＭ）、激光拉曼谱（ＬＲＳ）、电子顺磁共振（ＥＳＲ）等技术研究了晶体结构和晶粒尺寸的相互关系。试验表明：单斜相、四方相、立方相ＺｒＯ２的比表面能依次递减。因而，当晶粒尺寸减小至纳米级时，四方相和立方相都可变为室温下的稳态或亚稳态。     

Correction procedure for the electron microprobe analysis of porous materials

A correction method is proposed for the quantitative determination of stoichiometric ratios in porous materials by electron microprobe analysis. Analysis of this kind of material is complicated by an imperfect surface that can only be improved to some extent. The correction is based on a linear dependence (different for each element) of the analyses on a sum of weight concentrations of oxides. With this correction it is possible to use analyses affected by the imperfection of the surface with much better confidence compared to common normalisation. An example is presented for a series of ceramic superconductors Bi_2.1(SrCa)_2.9Cu₂O₈₊.     

秩消因子分析—荧光光度测定某些食物中的营养元素硒

本文应用秩消因子分析－荧光光度法测定了食物中营养元素硒的含量，与文献〔１〕报道的ＤＡＮ－荧光光度法测定结果比较，具有良好的统计学一致性，从而为简化实验操作，改善痕量硒测定的准确性和灵敏度提供了新的可能。     

“Statistical” symmetry with applications to phase transitions

Hermann proposed that mesomorphic media should be classified by assigning certain statistical symmetry groups to each possible partially ordered array. Two translational groups introduced were called superordinate and subordinate. We find that the average density in such a partially ordered medium has the superordinate symmetry ₁, while the pair correlation function has the subordinate symmetry ₂. A complete listing is made of all compatible combinations of ₁ and ₂ in two and three dimensions. This leads to more possible symmetries than Hermann obtained, e.g., also to nonstoichiometric crystals. The order parameter space for the systems is found to be the quotient space ₁/₂. In most cases it is identical to the order parameter space of low-dimensionalXY spin systems. The Landau free energy is expanded as functional of the two-particle correlation functionK; the translation group is found to be ₁×₂. A Landau mean-field theory can then be carried out by expanding the system free energy into a series of invariants of the active irreducible representations ofK and mapping the free energy onto that for anXY planar spin system. We predict novel critical behavior for transitions between mesomorphic phases and go nogo selection rules for continuous transitions. We give the structure factors for X-ray scattering so changes in all such phase transitions are observable. The statistical symmetry groups, which describe point and translational symmetries of the mesophases, are classified. Proposals are made to include quasi-long-range or topological order in the classification scheme.This work supported in part by National Science Foundation (Division of International Programs), the PSC-BHE—Faculty Research Award CUNY and Deutsche Forschungsgemeinschaft.     

石墨炉原子吸收法中热解涂层石墨管在无标准分析法测定环境样品中铬的应用

本文探讨了热解涂层石墨管测定铬的最佳实验条件,研究了各种酸和干扰物质的基体效应,提出用浓氨水为基体改进剂克服高氯酸的干扰。比较了各原子化温度时的理论和实验特征量。使热解涂层石墨管有可能用于无标准分析法测定各种环境样品中的铬。     

Application of similarity aggregation techniques to a population of paraplegic patients

We studied a population of paraplegic patients in order to give prominence to a possible relationship between the topography of their spinal lesion and the occurrence of special articular diseases (P.O.A.). According to the motor and sensory state of their spinal cord, we first tried to obtain a classification of these lesions (the usual one schematically separates ‘flaccid’ and ‘rigid’ paraplegics). We mainly put the emphasis on this clustering step of the study:

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