电化聚合聚吡咯的角分布X射线光电子能谱研究

用角分布Ｘ射线光电子能谱（ＸＰＳ）测试和样品原位加热相结合的方法研究了阴离子是对甲苯磺酸根的电生导电聚吡咯的化学和聚集态结构．其结果表明聚吡咯表面约几个原子层内原子的相对浓度依下述次序递减：Ｃ＞Ｏ＞Ｓ＞Ｎ；导电聚吡咯中的氮原子至少有吡咯氮和氧化态氮两种；在２００℃加热以后聚合物链不受影响，但阴离子向表面迁移，同时氧化态氮大大减少．     

细胞色素C的电化学行为研究

本文评述了细胞色素Ｃ电化学研究的发展概况，重点介绍了细胞色素Ｃ在促进剂作用下的电化学行为，促进剂种类，影响促进作用的因素及促进机理。     

化学发光消耗型锰传感器

化学和生物发光是由化学反应产生的一种光辐射,不需要任何光源。又由于它们具有高灵敏度、宽线性范围和相对比较便宜的仪器等优点,因而在化学和生物传感器领域引起了广泛的兴趣。已用于H_2O_2、乳酸和胆固醇等多种生物活性物质的测定,但未见有金属离子传感器的报道。本文发展了一种新型的全固态模式的消耗型锰离子化学发光传感器。该传感器将除待测物外的所有化学发光反应试剂全部固定在阴离子交换树脂Amberlyst A-27上,于化学发光反应之前,将一定量化学发光试剂从固定化试剂柱上洗脱,与样品中的锰离子产生化学发光。已成功地应用于水样中痕量锰离子的测定。每个固定化试剂柱可连续使用100次以上。 1 实验部分 1.1 仪器和试剂 化学发光传感器由流动系统和检测系统两部分组成。其中流动系统主要由蠕动泵、六通阀、固定化试剂柱和流通池组成。检测系统由光电信增管、负高压、放大器和记录仪组成(图1)。     

Effect of BaBiO3 and Ba0.6K0.4BiO3 additives on the rechargeability of manganese oxide cathodes in alkaline cells

The effect of the incorporation of small amounts (1–5 wt%) of semiconducting BaBiO₃ and metallic Ba_0.6K_0.4BiO₃ additives on the rechargeability of electrolytic manganese dioxide (EMD) cathodes in alkaline cells in the one-electron regime has been investigated. Both the BaBiO₃ and Ba_0.6K_0.4BiO₃ additives lead to better cyclability compared to the previously known binary oxide additive Bi₂O₃. X-ray diffraction patterns recorded before and after 30 cycles as well as cyclic voltammograms recorded after first and 30 cycles reveal that the better cyclability in the presence of BaBiO₃ and Ba_0.6K_0.4BiO₃ additives is due to the suppression of the formation of unwanted, electrochemically inactive birnessite and hausmannite phases and a shifting of the second-electron capacity of Mn to higher potentials.     

Feasibility of using solid sampling graphite furnace atomic absorption spectrometry for speciation analysis of volatile and non-volatile compounds of nickel and vanadium in crude oil

A method for the direct determination of volatile and non-volatile nickel and vanadium compounds in crude oil without previous treatment using direct solid sampling graphite furnace atomic absorption spectrometry is proposed. The crude oil samples were weighed directly onto solid sampling platforms using a microbalance and introduced into a transversely heated solid sampling graphite tube. In previous work of our group losses of volatile nickel and vanadium compounds have been detected, whereas other nickel and vanadium compounds were thermally stable up to 1300 and 1600 °C, respectively. In order to avoid this problem different chemical modifiers (conventional and permanent) have been investigated. With 400 μg of iridium as permanent modifier, the signal started to drop already after two atomization cycles, possibly because of an interaction of nickel (which is a catalyst poison) with iridium. Twenty micrograms of palladium applied in each determination was found to be optimum for both elements. The palladium was deposited on the platform and submitted to a drying step at 150 °C for 75 s. After that the sample was added onto the platform and submitted to the furnace program. The influence of sample mass on the linearity of the response and on potential measurement errors was also investigated using four samples with different nickel content. For the sample with the lowest nickel concentration the relationship between mass and integrated absorbance was found to be non-linear when a high sample mass was introduced. It was suspected that the modifier had not covered the entire platform surface, which resulted in analyte losses. This problem could be avoided by using 40 μL of 0.5 g L⁻¹ Pd with 0.05% Triton X-100. Calibration curves were established with and without modifier, with aqueous standards, oil-in-water emulsions and the certified reference material NIST SRM 1634c (trace metals in residual fuel oil). The sensitivity for aqueous standards and emulsions was close to that for SRM 1634c, making possible the use of aqueous standards for calibration. The limits of detection and quantification obtained for nickel and vanadium under this condition were found to be 0.02 and 0.06 μg g⁻¹, respectively, for both elements, based on 10 mg of sample. Nickel and vanadium were determined in the samples with (total Ni and V) and without the use of Pd (thermally stable compounds), and the concentration of volatile compounds was calculated by difference. The results were compared with those obtained by high-resolution continuum source graphite furnace atomic absorption spectrometry by emulsion technique; no significant differences were found for total Ni and V at the 95% confidence level according to a Student's t-test.     

ADSORPTION OF 2,4-DICHLOROBENZOXYACETIC ACID ONTO HYPERCROSSLINKED RESIN MODIFIED BY PHENOLIC HYDROXYL GROUP (AM-1)

INTRODUCTIONAdsorption has been considered to be the best available technology for removing organics from water in the USSafe Drinking Water Act[1]. Due to many drawbacks of activated carbon[2-7], the most widely used adsorbent,hypercrosslinked polymeric adsorbents developed by Tsyurupa and Davankov[8] have been increasingly viewedas an alternative to activated carbon for selective removal of specific organic substances from contaminatedwater[9-12], and series of researches have been do…     

Semiempirical calculation of electronic spectra of organic compounds by using the improved method of new-γ electron repulsion integral. Part 2. Polycyclic aromatic hydrocarbons (PAHs)

Excitation energies of 123 polycyclic aromatic hydrocarbons were calculated by incorporating the improved method of new-γ for the two-center electron repulsion integral into two semiempirical molecular orbital methods (CNDO/S and INDO/S). This variable method well reproduced experimental excitation energies of them. The average error of the improvement is about 0.162 (CNDO/S) or 0.237 eV (INDO/S) though the average error without the improvement is about 0.541 (CNDO/S) or 0.536 eV (INDO/S). The improvement was useful for the calculations of other organic compounds including hetero atoms, such as organic dye.     

丙酮肟与某些芳烃相互作用的~1H核磁共振研究

Hatton和Richards通过对酰胺分子的~1H NMR谱溶剂效应的研究,提出了DMF与苯生成分子络合物的模型.如果络合物按1:1生成,那么将出现一个“饱和点”,在这点上甲基的芳香溶剂诱导位移(ASIS)的变化趋势或程度将出现一个明显的变化,事实上随着苯的摩尔分数从0到1逐渐增加时,化学位移总是有规则的逐渐移向高场.这就显示了分子络合物观点的局限性.它能被一些研究者所支持和接受,是因为它能够解释两个甲基共振峰先重合而后又分离的现象.     

Geometry,stability and aromaticity of β-diketiminate-coordinated alkaline-earth compounds

Alkaline-earth (Ae) metals have attracted a wealth of interdependent research from synthetic chemists. In Ae-catalyzed organometallic reactions, β-diketiminate is a typical ligand used to stabilize Ae catalysts by forming six-membered rings comprising Ae metals. Herein, studies focusing on the configuration of β-diketiminate-coordinated Ae compounds observed that the CC and CN bonds are homogeneous and unchanged. Furthermore, energetic studies observed that the formation of the Ae-incorporated six-membered rings results in enhanced stability of >20 kcal/mol. The nucleus-independent chemical shifts, anisotropy of the induced current density, and molecular orbital analyses demonstrated the non-aromaticity of the β-diketiminate-coordinated Ae compounds. The improved stability of these compounds can be explained by the delocalization of the π electrons derived from the β-diketiminate moiety.