Sulfur radicals embedded in various cages of ultramarine analogs prepared from zeolites

The colored (greenish) products analogous to ultramarine obtained from zeolite A, cancrinite and erionite by means of high-temperature (500-800 °C) treatment of zeolites mixed with elemental sulfur and alkalis can maintain the original structure of the parent zeolite under certain preparation conditions. The ESR spectra of samples recorded at room temperature always indicate the presence of radicals S₃⁻ (the blue chromophore). The spectra of samples prepared from zeolites recorded at 77 K exhibit additional signals that could be assigned to the yellow chromophore (the radical S₂⁻) encapsulated inside the β or ε-cages. It is remarkable that in the case of products with preserved cancrinite structure, where the S₂⁻ radicals are encapsulated inside the ε-cages, the above signals are visible already at room temperature. It may result from retarded mobility of these species in small cancrinite cages.     

Oxime-induced reactivation of sarin-inhibited AChE: a theoretical mechanisms study

Oximes (especially oximate anions) are used as potential reactivators of OP-inhibited AChE due to their unique alpha-effect nucleophilic reactivity. In the present study, by applying the DFT approach at the B3LYP/6-311G(d,p) level and the M?ller-Plesset perturbation theory at the MP2/6-311G(d,p) level, the formoximate-induced reactivation patterns of the sarin-AChE adduct and the corresponding reaction mechanism have been investigated. The potential energy surface along the pathway of the reactivation reaction of sarin-inhibited AChE by oxime reveals that the reaction can occur quickly due to the relatively low energy barriers. A two-step process is a major pathway proposed for the studied reactivation reaction. Through the nucleophilic attack, the oximate first binds to the sarin-AChE adduct to form a relatively stable phosphorus complex. The regeneration of the serine takes place subsequently through an elimination step, which is expected to be competitive with the nucleophilic attacking process. The polarizable continuum model (PCM) has been applied to evaluate the solvate effects on the pathway. It is concluded that the reaction energy barriers are also low enough for the reaction to easily occur in solvent. The results derived from both the gas-phase model and the aqueous solvation model suggest that the studied oximate anion is an efficient antidote reagent for sarin-inhibited AChE.     

Deformed preprojective algebras of generalized Dynkin type

We introduce the class of deformed preprojective algebras of generalized Dynkin graphs (), (), , , and () and prove that it coincides with the class of all basic connected finite-dimensional self-injective algebras for which the inverse Nakayama shift of every non-projective simple module is isomorphic to its third syzygy .

     

K-F系统中的波前相位调制与光强调制的转换

研究在由一薄片Ｋｅｒｒ 介质与一块二维反馈镜组成的非线性光学系统中光波前相位与光强的转换过程。根据基尔霍夫衍射定理,导出了单一模式以及小畸变近似条件下多个模式的相位－ 光强转换关系的方程。结果证明：通过衍射,入射波前相位各阶Ｚｅｒｎｉｋｅ 模式成分的大小转换为反馈光光强的非线性调制。     

基于位相测量轮廓术的三维数字化仪的实验研究

介绍了基于位相测量轮廓术的三维数字化仪的原理和系统结构 ,阐述了一种有效的三维数字化方法。该方法具有精度高、速度快、可实现自动测量等特点。     

Investigation of Surface-Enhanced Raman Spectra of Human Gallstones on Colloidal Silver

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Experimental evidence and consequences of rare events in quantum tunneling

Tiny spatial fluctuations of tunnel barrier parameters are shown to have dramatic consequences on the statistical properties of quantum tunneling. A direct experimental evidence is provided that the tunnel current through metal-oxide junctions, imaged at a nanometric scale, exhibits broad statistical distributions extending over more than 4 orders of magnitude. Striking effects of broad current distributions are shown: the total tunnel transmission is dominated by few highly transmitting sites and the typical current density varies strongly with the size of the junction. Moreover, self-averaging of the tunnel current fluctuations occurs only for unexpectedly large junction areas. Received 1 April 1999     

氯丙基键合硅胶固定相色谱性能与应用 I.二取代苯及前列腺素差向异构体的分离

研究了氯丙基键合硅胶固定相的高效液相色谱性能和在分离二取代苯异构体、前列腺素差向异构体方面的应用,探讨了流动相组成、性质、ｐＨ值等对溶质保留和分离的影响,讨论了溶质保留机理和最佳色谱分离条件。对上述异构体进行了良好的分离,而且分离速度比一般的反相色谱体系要好。     

双电荷离子[C12H12N2O]2+和[C12H12N2S]2+的气相单分子分解反应研究

The unimolecular dissociation reactions of doubly charged ions were reported,which resulted from a tandem mass spectrometer and a reversed geometry double focusing mass spectrometer by electron impact.Mass analyzed ion kinetic energy spectrometry(MIKES) was used to obtain the kinetic energy releases in charge separation reactions of doubly charged ions.The intercharge distances between the two charges at transition states can be calculated from the kinetic energy releases.Transition structures of unimolecular dissociation reactions were infered from MIKES and MS/MS.     

吖啶作为检测试剂的磷霉素间接光度反相高效液相色谱研究

以吖啶为紫外检测试剂,研究了强极性弱紫外吸收磷霉素的间接光度色谱,探讨了检测试剂性质、浓度、pH值等因素对色谱保留和检测灵敏度的影响,提出一种测定磷霉素的新色谱方法。