抗坏血酸和尿酸在CPB现场修饰碳糊电极上的电化学行为及其选择性测定应用

研究了抗坏血酸(AA)和尿酸(UA)在裸碳糊电极(CPE)和溴化十六烷基吡啶(CPB)现场修饰碳糊电极(CPB/CPE)上的电化学行为.研究结果表明,在PBS水溶液中,AA和UA在CPB/CPE上氧化峰电流增加,峰电位负移,CPB/CPE对AA,UA电化学氧化反应产生了催化作用.微分脉冲法研究表明,在AA和UA共存体系中,AA和UA的氧化峰电位相差约220 mV,以此建立了AA和UA的电化学选择性测定方法.AA和UA的微分脉冲伏安氧化峰电流和其相应浓度分别在7.0×10-6～6.0×10-3 mol/L和5.0×10-7～6.0×10-4 mol/L的范围内呈良好的线性关系.在200倍AA共存时UA的检出限为5.0×10-6 mol/L,CPB修饰的碳糊电极直接应用于实际尿样中UA的测定.     

羟苯磺酸钙在溴代十六烷基吡啶自组装膜现场修饰碳糊电极上的电化学行为及应用

研究了羟苯磺酸钙(Calcium Dobesilate,CD)在溴代十六烷基吡啶(Cetylpyridinium Bromide,CPB)自组装膜现场修饰碳糊电极(CPB/CPE)上的电化学行为和电化学动力学性质。实验结果表明,在磷酸盐缓冲液(PBS)中CD在CPB/CPE上的氧化还原峰电流增加,氧化峰电位正移,还原峰电位负移,CPB/CPE对CD电化学氧化还原过程产生促进作用。用方波伏安法(SWV)考察了氧化峰电流与CD浓度的关系,结果表明CD氧化峰电流与其浓度在1.8×10-7~1.0×10-4 mol·L-1范围内呈良好的线性关系,相关系数r为0.9955,检出限(S/N=3)为8.0×10-8 mol·L-1,相对标准偏差(RSD)为1.9%~2.2%,回收率为99.4%~102%。     

抗坏血酸和尿酸在胶束体系中的电化学行为及选择性测定的应用

以玻碳电极为工作电极,在PBS中用循环伏安法研究了抗坏血酸(AA)和尿酸(UA)在胶束体系中的电化学行为。在溴化十六烷基吡啶(CPB)胶束体系中,AA和UA的氧化峰电流增加,峰电位负移;在十二烷基苯磺酸钠(SDBS)胶束体系中,AA和UA的氧化峰电流减小,峰电位正移。在CPB中,AA和UA的氧化峰电位相差约270 mV,以此建立了AA和UA的同时测定方法。用微分脉冲伏安法测定AA和UA的氧化峰电流分别在1.0×10-6~1.0×10-2mol/L和5.0×10-7~1.0×10-3mol/L的范围内与各自的浓度范围呈良好的线性关系。在200倍AA共存时UA的检出限为5.0×10-6mol/L。此方法可应用于人体尿样中UA的测定,结果令人满意。     

电还原柠嗪酸修饰电极对多巴胺和尿酸的电化学性质研究

采用循环伏安法制备了电还原柠嗪酸膜修饰碳糊电极(ECA/CPE),研究了多巴胺(DA)在该修饰电极上的电化学行为。在pH 7.0的磷酸盐缓冲溶液中,ECA/CPE对DA具有明显的电催化作用,且DA呈现出一对准可逆的氧化还原峰,其氧化峰电流与DA浓度在3.7×10-7~8.2×10-5mol/L和1.04×10-4~9.34×10-4mol/L范围内呈良好的线性关系,检出限为1×10-7mol/L(S/N=3)。使用微分脉冲伏安法,DA和尿酸(UA)在ECA/CPE上的氧化峰能完全分离,且峰电流与浓度呈良好的线性关系。该电极可用于盐酸多巴胺针剂中DA的测定以及人体尿液中UA的检测。     

亚硫酸盐在乙酰二茂铁修饰碳糊电极上的电催化氧化及其电化学动力学性质研究

研究了亚硫酸盐在乙酰二茂铁(AFc)修饰碳糊电极(AFc/CPE)上的电催化行为。研究结果表明,其在裸碳糊电极(CPE)上的行为比亚硫酸盐在AFc/CPE上的氧化峰电流增加约3倍,氧化峰电位负移360 mV,表明AFc/CPE对亚硫酸盐的电化学氧化具有良好的催化作用。用循环伏安法、计时电流法测定了亚硫酸盐在AFc/CPE上的电极过程动力学参数,测得电荷传递系数α为0.70,电催化氧化反应速率常数k为(4.91±0.05)×104(mol/L)-1.s-1。催化氧化峰电流与亚硫酸盐在5.0×10-4~1.1×10-2mol/L浓度范围内呈良好的线性关系,线性回归方程为Ipa(μA)=1.345 7.956c(10-3mol/L),R=0.9988,检出限为2.0×10-5mol/L。可用于亚硫酸盐的电化学定量测定方法。     

多巴胺在聚溴甲酚绿修饰碳糊电极上的电化学行为

以碳糊电极(CPE)为基底,采用电聚合方法制备出聚溴甲酚绿修饰碳糊电极(PBG/CPE),运用循环伏安法(CV)对修饰电极进行表征,通过扫描电子显微镜(SEM)对聚合膜的表面形貌进行观察分析。利用PBG/CPE研究了多巴胺(DA)的电化学行为,并对最佳实验条件进行了探讨。研究结果表明:DA在PBG/CPE上于0.32V和0.24V处分别出现一对可逆氧化还原峰,PBG/CPE对DA有显著的催化作用,该催化过程受吸附控制。DA催化氧化还原峰电流与其浓度在1.0×10-5~2.0×10-4mol/L范围内呈现良好的线性关系,检出限为1.0×10-6mol/L。     

尿酸和抗坏血酸在CPB现场修饰碳糊电极上的电化学行为

研究了尿酸(UA)和抗坏血酸(AA)在裸碳糊电极(CPE)和溴化十六烷基吡啶CPB)现场修饰碳糊电极(CPB/CPE)上的电化学行为,研究结果表明在PBS(pH=6.8)缓冲溶液中,UA和AA在CPE和CPB/CPE电极上的氧化均为一不可逆过程,在CPB/CPE上UA和AA的氧化峰电位负移,氧化峰电流增大,CPB/CPE对UA和AA的电化学氧化产生了促进作用。用电化学方法测得了UA和AA在CPE和CPB/CPE上的动力学参数如电荷转移系数α,扩散系数D,反应级数和反应速率常数k1。     

多巴胺在聚钙羧酸膜修饰碳糊电极上的电催化及与尿酸的同时测定

采用循环伏安法(CV)制备了聚钙羧酸(PCCA)膜修饰的碳糊电极(CPE)。考察了电极对多巴胺(DA)、尿酸(UA)的电氧化催化性能。结果显示,聚钙羧酸膜修饰碳糊电极(PCCA/CPE)对DA有良好的电催化效果,DA呈现出一对准可逆的氧化还原峰,氧化峰电流与DA浓度在3.0×10-7～1.0×10-4mol/L范围内呈线性关系,检出限为1×10-7mol/L(S/N=3)。使用微分脉冲伏安法(DPV),DA和UA在PCCA/CPE上的氧化峰能完全分离(ΔEp=192 mV),且峰电流与浓度均呈现良好的线性关系,可实现对DA和UA的同时测定。实验还进行了实际样品测定。     

抗坏血酸在聚对羟基苯甲酸修饰玻碳电极上的催化电氧化行为

通过循环伏安(CV)制备了聚对羟基苯甲酸(poly-PHB)修饰的玻碳电极. 考察了电极对抗坏血酸(AA)电氧化的催化性能. 结果显示,聚对羟基苯甲酸修饰玻碳电极对AA氧化有很好的电催化作用. 在修饰电极上产生的峰电流比在未修饰电极上产生的氧化峰电流大4倍,氧化峰电位负移205 mV. 氧化峰电流与AA浓度在2.6×10-5～3.68 ×10-4 mol/L范围内呈线性关系,相关系数为0.998 4,检测限为5×10-6 mol/L(S/N=3). 在AA与多巴胺(DA)共存的体系中,能排除DA对抗坏血酸测定的干扰.     

嵌入式超薄微晶纤维素/碳糊电极的构建及应用

以镍铬合金为基体,在其表面通过直接嵌入微晶纤维素修饰的碳糊膜,构建了嵌入式超薄微晶纤维素/碳糊电极(ISM/CPE). 用扫描电子显微镜和循环伏安法表征了电极的特性;以抗坏血酸(AA)为目标物考察其在该电极上的电化学行为. 结果表明,在ISM/CPE上,AA的氧化峰电位为0.38 V,较传统碳糊电极负移了0.05 V;峰电流与AA的浓度在1.0×10-6～1.0×10-3 mol/L范围内呈良好线性关系,相关系数r=0.999 3,检测限(S/N=3)为7.5×10-7 mol/L. 表明合金表面嵌入的超薄微晶纤维素/碳糊膜,改变了基体电极的电化学性质,可用于实际样品中AA的测定.     

多环芳二酐型聚酯亚胺膜的透气性能

多环芳二酐型聚酯亚胺膜的透气性能李悦生，丁孟贤，徐纪平（浙江大学高分子科学与工程研究所，杭州，３１００２７）（中国科学院长春应用化学研究所）关键词聚醚酰亚胺，聚酯酰亚胺，膜，透气性通常的聚酰亚胺加工性能较差，在芳环二酐的苯环间引入醚键等柔性基团后，其...     

微量元素与疾病诊断治疗的研究现状及展望

对国内外微量元素与疾病的关系及其诊断治疗的研究现状及研究动向进行了综述，包括：微量元素与地方病、癌肿、心血管病、糖尿病、眼病、神经系统病等。参考文献72篇。     

Determination and study on residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil

A QuEChERS (quick, easy, cheap, effective, rugged, and safe) method for the determination of benazolin-ethyl and quizalofop-p-ethyl in rape and soil by high-performance liquid chromatography-tandem mass spectrometry has been developed in this study. The residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil were determined with the developed method. The half-lives of benazolin-ethyl in rape straw and soil were 3.7–5.1 days and 14.3–26.3 days, respectively. The half-lives of quizalofop-p-ethyl in rape straw and soil were 5.0-6.1 days and 0.3–9.7 days, respectively. The residue of benazolin-ethyl and quizalofop-p-ethyl in rapeseed and soil were below the detection limit (i.e., 0.5?mg?kg^?1, the maximum residue level of European Union for quizalofop-p-ethyl).     

Synthesis and Optical and Redox Properties of Symmetric and Asymmetric BODIPYs

Herein, we present the synthetic route and the photophysical, electrochemical as well as laser properties of novel red‐emitting boron‐dipyrromethenes (BODIPYs) bearing arylethyne moieties. Such functionality is added along the main axis of the chromophore leading to single‐ and double‐substituted derivatives. The relationship between the dye structure and the lasing properties is studied in detail with the help of the photophysical and electrochemical properties as well as quantum mechanical simulations. The asymmetric substitution of the parent dye induces inhomogeneities in the charge distribution, which leads to an overall loss of the fluorescence capacity, mainly in polar media. Such non‐radiative deactivation processes can be softened by decreasing the electron‐donor ability of the substituent or even avoided by symmetrical substitution. Thus, grafting of the arylethyne moieties at the longitudinal axis of the indacene core results in an effective strategy to develop red‐edge BODIPYs with highly efficient and photostable laser emission.     

Ti-V基储氢合金及其氢化物的物相结构与组分优化设计

Ti-V基储氢合金在室温、常压下即可表现出良好的储氢特性,且质量储氢容量明显高于传统AB₅型储氢合金,从而在氢气的精制和回收、运输和储存及热泵等方面有较早的应用。 此外,在混合气体分离、核反应堆中处理氢的同位素、镍氢电池及燃料电池负极材料等方面也得到了广泛的研究与关注。 基于目前Ti-V基储氢合金的研究现状,概述了该类合金的优势、限制性因素(包括成因)及改性手段。 此外,为了进一步理解Ti-V基合金储氢机理、构建合金组分与储氢特性之间的对应关系,本工作重点围绕Ti-V基储氢合金及其氢化物的结构、组分优化设计展开综述,并对其未来研究方向做出展望。     

钒与糖代谢及糖尿病

微量元素钒作为生物体内必需元素，经证实有很重要的生理学功能，与机体糖代谢有十分密切的关系，且能降低糖尿病动物模型的高血糖，极有可能被开发为治疗糖尿病的药物。     

Conformations and steric and stacking interactions of trisubstituted ureas and thioureas with alkyl and phenyl groups

The monomeric ν(N—H) vibrations of various trisubstituted ureas of the R₂UPh type and -thioureas of the R₂TUPh type have been studied. The trans—out isomerism in the former and the trans—out—cis isomerism in the latter are discussed from the point of view of steric effect. The monomeric ν(N—H) vibrations of RPhUPh and RPhTUPh are also examined. The single band appearing in the spectrum of both ureas is characteristic of the cis form; this suggests the existence of phenyl—phenyl interaction (the stacking interaction proposed by Galabov et al. [10]). Behavior of ν(N—H) vibrations at several concentrations is shown to be clearly different in the three forms (trans, out and cis). The presence of the cis form is confirmed by solvent effect experiments.     

Synthesis of Tyrosol and Hydroxytyrosol Glycofuranosides and Their Biochemical and Biological Activities in Cell-Free and Cellular Assays

Tyrosol (T) and hydroxytyrosol (HOT) and their glycosides are promising candidates for applications in functional food products or in complementary therapy. A series of phenylethanoid glycofuranosides (PEGFs) were synthesized to compare some of their biochemical and biological activities with T and HOT. The optimization of glycosylation promoted by environmentally benign basic zinc carbonate was performed to prepare HOT α-L-arabino-, β-D-apio-, and β-D-ribofuranosides. T and HOT β-D-fructofuranosides, prepared by enzymatic transfructosylation of T and HOT, were also included in the comparative study. The antioxidant capacity and DNA-protective potential of T, HOT, and PEGFs on plasmid DNA were determined using cell-free assays. The DNA-damaging potential of the studied compounds for human hepatoma HepG2 cells and their DNA-protective potential on HepG2 cells against hydrogen peroxide were evaluated using the comet assay. Experiments revealed a spectrum of different activities of the studied compounds. HOT and HOT β-D-fructofuranoside appear to be the best-performing scavengers and protectants of plasmid DNA and HepG2 cells. T and T β-D-fructofuranoside display almost zero or low scavenging/antioxidant activity and protective effects on plasmid DNA or HepG2 cells. The results imply that especially HOT β-D-fructofuranoside and β-D-apiofuranoside could be considered as prospective molecules for the subsequent design of supplements with potential in food and health protection.     

Ferrocene and ferrocenium modified clays and their styrene and EVA composites

In this work, ferrocene- and ferrocenium-containing salts were employed to modify montmorillonite. X-ray measurements show an increase in the interlayer spacing upon clay modification, which means that the larger and more organophilic cations were inserted into the gallery space of montmorillonite. Attempts to prepare nanocomposites of polystyrene and ethylene vinyl acetate copolymers lead to immiscible systems; the morphology of these systems was elucidated with TEM, XRD and cone calorimetry. The thermal stability of the composites is greater than that of the virgin polymer.