聚苯乙烯磺酸掺杂聚苯胺的合成

以苯胺（An）为单体，过硫酸铵（APS）为氧化剂，在聚苯乙烯磺酸（PSSA）的水溶液中，合成了可完全溶于水的PSSA掺杂PAn。研究了An浓度，PSSA浓度，APS浓度，APS的滴加时间，反应时间及温度对An聚合反应及其产物的水溶性，导电性及特性粘度[η]的影响。结果表明：在比较宽的实验条件下，都可以合成出具有良好导电性的可溶于水的PSSA掺杂PAn；其中当An：PSSA:APS的摩尔比为1．7：2．5：1，APS溶液的滴加时间为3h，反应时间为1h，反应温度为14℃时，得到的掺杂PAn导电率最高达0．156S／cm。     

EPO检测技术的研究进展

促红细胞生成素（EPO）是一种临床上广泛应用的重要药物，也是近年来兴奋剂检测的热点。本文主要从EPO的产生和应用出发，对EPO的结构、特性及其检测方法进行了介绍及评价，重点探讨了竞技体育中EPO的检测技术，并对检测前景作了展望。     

Influence of vanadium doping on the behavior of YBa_2Cu_3O_7-y

YBa2Cu3-xVxO7-y(x=0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) superconductors have been prepared. X-ray diffraction shows that the system remains orthorhombic for all compositions studied, but for x > 0.4 V2O5 was detected as an impurity phase. Substitution of V5+ for Cu2+ occurs in the Cu(2) sites on the Cu(2)-O planes. The introduction of the high valence element, vanadium, produces the extra free-electrons. These electrons recombine with the positive carrier of the system. It makes depression of the mobility and the Hall number of YBa2Cu3-xVxO7-v and also results in a depression of TC.     

Origin of visible-light-driven photocatalysis: A comparative study on N/F-doped and N-F-codoped TiO2 powders by means of experimental characterizations and theoretical calculations

An overall comparative study was carried out on N-doped, F-doped, and N-F-codoped TiO₂ powders (NTO, FTO, NFTO) synthesized by spray pyrolysis in order to elucidate the origin of their visible-light-driven photocatalysis. The comparisons in their experimentally obtained characteristics were based on the analysis of XPS, UV-Vis, PL, NH₃-TPD and ESR spectra. The comparisons in their theoretically predicted properties were based on the analysis of the calculated electronic structures. As the results, N-doping into TiO₂ resulted in not only the improvement in visible-light absorption but also the creation of surface oxygen vacancies. F-doping produced several beneficial effects including the creation of surface oxygen vacancies, the enhancement of surface acidity and the increase of Ti³⁺ ions. Doped N atoms formed a localized energy state above the valence band of TiO₂, whereas doped F atoms themselves had no influence on the band structure. The photocatalytic tests indicated that the NFTO demonstrated the highest visible-light activity for decompositions of both acetaldehyde and trichloroethylene. This high activity was ascribed to a synergetic consequence of several beneficial effects induced by the N-F-codoping.     

Fluorine-doped TiO2 powders prepared by spray pyrolysis and their improved photocatalytic activity for decomposition of gas-phase acetaldehyde

F-doped TiO₂ (FTO) powders were synthesized by spray pyrolysis (SP) from an aqueous solution of H₂TiF₆. The resulting FTO powders possessed spherical particles with a rough surface morphology and a strong surface acidity. The fluorine concentrations in the FTO powders calculated from XPS spectra significantly depended on SP temperature and ranged from 2.76 to 9.40 at.%. The FTO powder prepared at SP temperature of 1173 K demonstrated the highest photocatalytic activity for the decomposition of gas-phase acetaldehyde under both ultraviolet (UV) and visible light (vis) irradiations, and it was higher than that of commercial P 25. This high photocatalytic activity was ascribed to several beneficial effects produced by F-doping: enhancement of surface acidity, creation of oxygen vacancies, and increase of active sites. It was interesting to point out that the vis photocatalytic activity of FTO powders was achieved by the creation of surface oxygen vacancies rather than the improvement of optical absorption property of bulk TiO₂ in vis region.     

Oxygen Dependence in a Dual‐Phase Electrochemical Biosensing System

Oxygen dependence of a tyrosinase‐based electrochemical biosensor for determination of phenol in aqueous and organic media was systematically investigated. The result demonstrated that the enzymatic coupling reaction rate of tyrosinase (deoxy form) and O₂ to regenerate tyrosinase (oxy form) is a kinetically fast reaction, and the significant change of O₂ concentration in aqueous solution did not affect the coupling reaction. The further increase of O₂ concentration did not increase the overall oxidation reaction rate of the substrate at low substrate concentration (e.g.,<10 μM phenol) when O₂ concentration was greater than 8.9 ppm. The oxygen dependence was observed in the case of high substrate concentration due to insufficient amount of O₂ available for the regeneration of tyrosinase. In other words, the upper linear range is oxygen dependent for tyrosinase biosensors. The phenol biosensors employing microelectrodes had wider upper linear ranges than macroelectrodes in both aqueous and organic phase, which can be explained by the oxygen dependence.     

Conventional hydrothermal process versus microwave-assisted hydrothermal synthesis of La1−xAgxMnO3+δ (x = 0, 0.2) perovskites used in methane combustion

A study on the synthesis of La_1−xAg_xMnO_3+δ (x = 0, 0.2) using a microwave process (MWhyd) has been carried out by comparing the heating time and reaction temperature with the same factor under conventional thermal process (CHhyd). Experiments have been conducted using the hydrothermal method at medium pressure (T = 200 °C, P = 20 atm) followed by a thermal treatment of the precursor at 700 °C (10 h).Structural and physico-chemical properties of the catalysts were investigated using X-ray diffraction (XRD), BET sorption, temperature-programmed reduction or desorption, mass spectrometry (TPR-MS and TPD-MS), and X-ray photoelectron spectroscopy (XPS). While CHhyd and MWhyd powder catalysts exhibited the same XRD patterns indexed as pure perovskite structure, their surface physico-chemical properties were found to be strongly influenced by the preparation method. The effect of the nature of oxygen species, their amount and mobility, evidenced by temperature programmed experiments, on the catalytic properties in methane combustion in the presence and in the absence of hydrogen sulphide has been studied. MWhyd-La_0.8Ag_0.2MnO_3+δ catalysts were found to exhibit a much better performance in methane combustion together with higher resistance to sulphur poisoning than CHhyd catalysts.     

Three-component coupling using arynes and isocyanides: straightforward access to benzo-annulated nitrogen or oxygen heterocycles

A variety of aldehydes, ketones, benzoquinones, or sulfonylimines were found to couple with arynes and isocyanides, giving iminodihydroisobenzofuran or iminoisoindoline derivatives of structural diversity in a straightforward manner. Nucleophilic addition of isocyanides to arynes, a first step of the three-component coupling, was proved to be reversible by the reaction of an unsymmetrical aryne.     

Optical Nanocomposite Planar Waveguides Doped with Rare-Earth and Noble Metal Elements

The present paper is focused on multilayer Er³⁺-doped silica-titania planar waveguides, co-doped with silver, which were prepared by spin-coating on silica glass, or buffered single crystal silicon substrates. The single layer thickness (0.4 m) and refractive index (1.60–1.63) were measured by spectroscopic ellipsometry at 715 nm. The thickness of the waveguides (measured by mechanical profilometry) was 1 m and their optical propagation losses were measured at different laser wavelengths (488 nm, 514 nm and 633 nm), exhibiting an approximately Rayleigh-like behavior. The thermal precipitation of silver nanocrystallites was achieved, both in air and under a controlled atmosphere (dry nitrogen) and these were characterized by visible absorption spectroscopy, which clearly showed the development of a plasmon absorption band near 415 nm, by X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The Er³⁺ metastable level lifetimes for the emission at ca. 1.54 m were found to be ca. 4–6 ms, for Er³⁺ concentrations varying between 0.2–2.0 mol% (or (0.4–4.4) × 10²⁰ ions/cm³), but no significant variation was observed with the Ag concentration added (up to 2.5 mol%).     

Calculation of Vertical Ionization Potentials of Oxygen Difluoride,Difluoramine, and Difluoromethane by Local Density Approximation

The vertical ionization potentials of OF₂, HNF₂, and CH₂F₂ were computed by the deMon density functional program. The results are compared with earlier calculations and with experiment. The average absolute deviation of the 21 computed ionization potentials of the outer valence electrons from experiment is 0.44 eV, which compares well with 0.37 eV for frozen-orbital configuration-interaction calculations. Although this performance is not as good as perturbation corrections to Koopmans' theorem, the computation requirements are much less demanding.