A novel thin-layer amperometric detector based on chemically modified ring-disc electrode and its application for simultaneous measurements of nitric oxide and nitrite in rat brain combined with in vivo microdialysis

A novel thin-layer amperometric detector (TLAD) based on chemically modified ring-disc electrode and its application for simultaneous measurements of nitric oxide (NO) and nitrite (NO₂⁻) in rat brain were demonstrated in this work. The ring-disc electrode was simultaneously sensitive to nitric oxide (NO) and nitrite (NO₂⁻) by modifying its inner disc with electropolymerized film of cobalt(II) tetraaminophthalocyanine (polyCoTAPc)/Nafion and its outer ring with poly(vinylpyridine) (PVP), respectively. The ring-disc electrode was used to constitute a novel TLAD in radial flow cell for simultaneous measurements of NO and NO₂⁻ in rat brain combined with techniques of high performance liquid chromatography (HPLC) and in vivo microdialysis. It was found that the basal concentration of NO in the caudate nucleus of rat brain is lower than 1.0×10⁻⁷ mol l⁻¹, NO₂⁻ concentration is 5.0×10⁻⁷ mol l⁻¹ and NO exists in brain maybe mainly in the form of its decomposed product.     

Synthesis and Crystal Structure of Trigadolinium Bromoorthosilicate，Gd_3Br（SiO_4）_2

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Some observations on the synergistic extraction of uranium(VI) with double chelating agent systems

A study on the synergistic extraction of uranium(VI) from nitric acid media with double-chelating agent systems 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (PMBP) plus thenoyltrifluoroacetone (TTA), and 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 plus 1-phenyl-3-methyl-4-trifluoroacetyl-pyrazolone-5 (PMTFP) is described. Some synergistic effects have been observed. The experimental results suggest that the composition of synergistic complex species is UO₂PMBP·TTA and UO₂PMBP·PMTFP, respectively. The equilibrium constants for these synergistic extractions are calculated by three methods and the mechanism and the regularity of extraction are discussed as well.     

A Novel Dimeric Coumarin from Clausena lenis

A novel dimeric coumarin (1), a dimeric of seselin named diseselin A, was isolated from the aerial part of Clausena lenis. The structure was elucidated based on the MS, 1D and 2D NMR data.     

CO(υ)高振动激发态向C2H2的振动传能研究

用时间分辨富里叶红外发射谱研究了高振动激发态ＣＯ向Ｃ２Ｈ２的传能，得到了ＣＯ（ｖ＝１－３）各振动态布居及其随时间的变化。利用微分法解出弛豫微分方程组，获得ＣＯ（ｖ＝１－３）向Ｃ２Ｈ２的传能速率常数分别为：２．０±０．１，６．０±０．２和９．４±０．８（１０＾－１３ｃｍ＾３·ｍｏｌｅｃｕｌｅ＾－１·ｓ＾－１）。传能速率随着振动量子数的增加而迅速增加。ＣＯ的振动能应向Ｃ２Ｈ２的对称伸缩模ｖ２近共振Ｖ－     

聚丙烯与SBS嵌段共聚物共混时的结晶行为

用偏光显微镜,小角光散射,动态力学测量和DSC等方法研究了聚丙烯和SBS共混物的结晶行为。结果表明,SBS的混入可以降低聚丙烯的结晶程度和阻碍球晶的形成,因而有利于提高聚丙烯塑料的抗冲击性能。从DSC实验也看到共混物中的聚丙烯具有较高的结晶速率。     

Laser ablation in analytical chemistry-a review

Laser ablation is becoming a dominant technology for direct solid sampling in analytical chemistry. Laser ablation refers to the process in which an intense burst of energy delivered by a short laser pulse is used to sample (remove a portion of) a material. The advantages of laser ablation chemical analysis include direct characterization of solids, no chemical procedures for dissolution, reduced risk of contamination or sample loss, analysis of very small samples not separable for solution analysis, and determination of spatial distributions of elemental composition. This review describes recent research to understand and utilize laser ablation for direct solid sampling, with emphasis on sample introduction to an inductively coupled plasma (ICP). Current research related to contemporary experimental systems, calibration and optimization, and fractionation is discussed, with a summary of applications in several areas.     

Molecular films of water-miscible ionic liquids formed on glassy carbon electrodes: characterization and electrochemical applications

This letter describes the formation and possible electrochemical applications of molecular films of water-miscible imidazolium-based ionic liquids (ILs) on glassy carbon (GC) electrodes. X-ray photoelectron spectroscopy (XPS) and electrochemical results indicate that the water-miscible ILs used in this study can interact with the GC electrode and form molecular films on the electrode surface. The formed molecular films are found to possess striking electrochemical properties such as electrocatalysis toward ascorbic acid (AA) and the capability to facilitate direct electron transfer of horseradish peroxidase (HRP). This demonstration would pave the way for new electrochemical applications of water-miscible ILs and is envisaged to be useful for the investigation of the electrochemical properties of water-miscible ILs in aqueous media provided the same counteranion is used as the supporting electrolyte.     

The effect of B2O3 addition on the crystallization of amorphous TiO2-ZrO2 mixed oxide

The effect of B₂O₃ addition on the crystallization of amorphous TiO₂-ZrO₂ mixed oxide was investigated by X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG/DTA). TiO₂-ZrO₂ mixed oxide was prepared by co-precipitation method with aqueous ammonia as the precipitation reagent. Boric acid was used as a source of boria, and boria contents varied from 2 to 20 wt%. The results indicate that the addition of small amount of boria (<8 wt%) hinders the crystallization of amorphous TiO₂-ZrO₂ into a crystalline ZrTiO₄ compound, while a larger amount of boria (?8 wt%) promotes the crystallization process. FT-IR spectroscopy and ¹¹B MAS NMR results show that tetrahedral borate species predominate at low boria loading, and trigonal borate species increase with increasing boria loading. Thus it is concluded that highly dispersed tetrahedral BO₄ units delay, while a build-up of trigonal BO₃ promote, the crystallization of amorphous TiO₂-ZrO₂ to form ZrTiO₄ crystals.     

An in situ STM study on the long-range surface restructuring of Au(1 1 1) in a non-chloroaluminumated ionic liquid

We report an in situ STM study of a potential-dependent long-range surface restructuring of Au(1 1 1) electrode in neat 1-butyl-3-methylimidazolium tetrafluoroborates (BMIBF₄) ionic liquid. Au(1 1 1) undergoes a significant long-range surface restructuring upon cathodic excursion to −1.0 V vs. Pt quasi-reference. The restructuring involves the formation of tiny pits, which then develops into a stable worm-like network with an average width of the network grids 2 nm. Electrochemical annealing occurs at the cathodic limit with the presence of a reduction product of cation BMI⁺. A smooth surface is recovered with the appearance of the typical (√3 × 22) reconstruction of Au(1 1 1). The surface restructuring is reestablished upon anodic excursion to −1.3 V after the adsorbed reduction product is oxidized. The long-range surface restructuring phenomenon is tentatively explained as a result of partial charge transfer to the weakly adsorbed BMI⁺, which reduces the metal–metal cohesive energy. In addition, the synergetic effect of the counter anion BF₄⁻ may also be involved. The results provide a knowledge of Au(1 1 1) electrode behavior in the neat ionic liquid and are beneficial to understanding in situ STM results involving surface morphological changes in such a media.