Preparation and characterization of periodic mesoporous organosilica terminally functionalized with fluorocarbon groups by a direct synthesis

Fluorocarbon groups were used to modify the pore channels of ethane-bridged periodic mesoporous organosilica by the co-condensation of 1,2-Bis(triethoxysilyl)ethane (BTESE) and trifluoropropyltrimethoxysilane (TFPTMS) in the presence of Poly(ethylene glycol)-B-Poly(propylene glycol)-B-Poly(ethylene glycol) (P123) surfactants under acidic conditions. The functionalized materials were investigated in detail by means of XRD, TEM, FT-IR, solid-state NMR, and N₂ adsorption. The effect of fluorocarbon groups concentration on the mesoscopic order and pore structure of the functionalized materials was also studied. The results show that bridging groups in the framework do not cleave and fluorocarbon groups are attached covalently to the pore wall of periodic mesoporous organosilica after functionalization. The samples functionalized with 20% TFPTMS remain desired mesoporous architecture, with a narrow pore size distribution centered at 4.1 nm, a large surface of 834 m²/g and a pore volume of 0.91 cm³g⁻¹, without pronounced change compared to the pure periodic mesoporous organosilica. Unfortunately the functionalized materials become structurally disordered with increasing amount of fluorocarbon groups.     

萘相吸光光度法研究

本文以萘作为固体萃取剂，以镍－丁二酮肟显色体系为例进行实验，探索出一种新的固相吸光光度法－萘相吸光光度法。镍在０－１００μｇ／５０ｍＬ范围内符合比耳定律，方法应用于水样中痕量镍的分析，结果良好。此种新的分析方法分离富集和显色测定两步相结合。灵敏度高，选择性好，快速简便，是一种很有发展前途的痕量元素分析方法。     

低剂量氯化钐对大鼠血清激素水平的影响

应用放射免疫法测定了经腹腔注射、灌胃入尾静脉注射等３种不同方式，隔日给预寺鼠低剂量氯化钐０．０５ｍｇ／ｋｇ，一个月后，测试血清中生长激素，甲状腺素Ｔ３、Ｔ３及胰岛素水平。结果显示各实验组动物血清中生长激素、胰岛素水平均明显增高，甲状腺素Ｔ４及腹腔注射增高，其余两组无明显变化。     

Titrations with piezoelectric monitoring : Part 1. Fundamental theory and titration of acids and bases

The use of a piezoelectric quartz crystal detector is proposed for monitoring the course of a titration reaction by observation of the frequency shift of the oscillating crystal. Satisfactory titrations can often be obtained using the acid-base technique, which is much more sensitive than the classical conductimetric titration and oscillometric titrration, with a lowest titratable concentration that is much lower but which can still be applied in the presence of a large amount of unreacting electrolyte.     

Catalytic asymmetric synthesis of N-substituted tetrahydroquinoxalines via regioselective Heyns rearrangement and stereoselective transfer hydrogenation in one pot

N-Substituted tetrahydroquinoxalines (37 examples) were step-economically obtained in good yield (<97%) and ee (<99%) with readily available substrates. The reaction proceeds through an interesting regioselective Heyns rearrangement/enantioselective transfer hydrogenation in one pot. The substrate scope and the reaction mechanism were systematically investigated.

N-Substituted tetrahydroquinoxalines were step-economically obtained in good yield and ee with readily available substrates.     

Drug discovery based on the structure of FKBP12: Design,synthesis and evaluation of <Emphasis Type="Italic">L</Emphasis>-1,4-thiazane-3-carboxylic acid derivatives as neuroimmunophilin ligands

By choosing neuroimmunophilin FKBP12 as a therapeutical target, we have attempted to discover a new structural drug for treating neurodegenerative disease. This drug should possess neurotrophic activity and not affect the immune system. Based on the crystal structure of FKBP12, FK506 and Calcineurin complex, a series of small organic molecules were designed. These molecules were to have the ability of binding to FKBP12 in a virtual screening. By using a solution parallel synthetic method, these compounds were synthesized. The neuroprotective and neuroregenerative activities of these compounds were evaluated by binding assays, PC12 cells survival and neurite outgrowth model, chick dorsal root ganglion cultures (DRG) and 6-OHDA lesioned mice sympathetic nerve endings model. The evaluation results of these compounds showed that compound N308 has great promise as a candidate for a neuroprotective and neuroregenerative agent. Supported by the National Basic Research Program of China (Grant No. G1998051107) and Hi-tech Research and Development Program of China (Grant No. 2002AA233051)     

Preparation, structure, and electrochemistry of a polypyrrole film doped with manganese(III)-substituted Dawson-type phosphopolyoxotungstate

The fabrication, structure, electrochemical properties, and electrocatalytic properties of a manganese(III)-substituted Dawson-type phosphopolyoxotungstate, alpha 2-K7P2W17O61(Mn3+.OH2).12H2O (P2W17Mn), entrapped in polypyrrole (PPy) film have been studied. The hybrid film was prepared by potentiostatic polymerization from aqueous solution containing 20 mM pyrrole (Py) and 2 mM P2W17Mn on a pyrolytic graphite (PG) surface. Chronoamperometry, Raman spectroscopy, UV-visible absorption spectroscopy, and cyclic voltammetry were used to monitor and characterize the growth, structure, and properties of the film. The chronoamperometric curve shows that P2W17Mn can catalyze the electrochemical polymerization of Py. The Raman spectrum suggests that the doped P2W17Mn has little effect on the structure of PPy film. The P2W17Mn/PPy film exhibits good voltammetric response in both the acidic aqueous and acetonitrile solutions. At pH 1.0, the molar ratio of pyrrole to P2W17Mn7- in the hybrid film is 21.1:1, quite close to the expected ratio of 21.2:1 for a PPy film with a +0.33 oxidation level per pyrrole moiety and doped with an anion with a charge of 7. The influence of solution pH on P2W17Mn7- in the film is much smaller than that in the aqueous solution. During the potential scanning in 0.1 M LiClO4 acetonitrile solution, P2W17Mn7- was slowly released from the hybrid film and electrolyte ions (Li+ and ClO4-) were inserted into the film. This was identified by cyclic voltammetry and UV-visible spectroscopy. Additionally, the hybrid film can effectively catalyze the reduction of hydrogen peroxide and nitrite.     

Titrations with piezoelectric monitoring : Part 2. Compleximetric titrations and precipitation titrations

A piezoelectric detector is used to monitor titration reactions involving complex formation or precipitation. Analytes at concentrations down to 10^?4 mol 1^?1 can be determined. The frequency shift in the compleximetric titrations is affected by the composition of the solution, the buffer and competing ligands present in the solution. Factors influencing the frequency shift in the precipitation titration are also investigated.     

杯[4]芳烃锥形骨架在光学受体识别中的作用

比较研究了铜、镍的杯[4]芳烃光学受体及其单体的分析性能，并进一步探讨了杯[4]芳烃的锥形骨架在分子识别中的作用。结果表明，通过分子设计，将杯[4]芳烃锥形骨架合理地引至光学受体中，可以起到立体屏障作用，能有效阻止其它客体在一些方向上靠近配位反应点所带来的干扰，从而对客体的选择性识别提供重要贡献。     

Theory of the surface acoustic wave/impedance sensor system and its application to the end-point determination in titrimetry

Theory and characteristics of the surface acoustic wave (SAW)/impedance sensor system in electrolyte solution are reported. This kind of sensor was constructed by a 62-MHz SAW resonator and a pair of conductive electrodes in series. By using the circuit network analysis theory, two oscillation equations were derived and used to explain the frequency-shift response to solution conductance. Results showed that the sensor possesses high sensitivity to the solution conductivity and can be applied to conductivity measurements in solution. Its sensitivity and accuracy could be improved in the presence of a large amount of unreacting foreign electrolytes. The sensor was successfully applied to four types of titration (acid-base, precipitation, oxidation-reduction and compleximetric titration) by monitoring the frequency-shift response. Factors influencing the frequencimetric titration curve were also investigated. Analytes at levels down to 1 × 10⁻⁵ M could be determined by the proposed titration technique. The total acidity in several food samples was determined and the results were consistent with those obtained by conventional methods.