Poly(Methyl Red) Modified Glassy Carbon Electrodes: Electrosynthesis,Characterization, and Sensor Behavior

Poly(methyl red), PMR, was electropolymerized on glassy carbon electrodes by potential cycling in 50 mM phosphate buffer solution at pH 7.0 and 8.0 and Britton Robinson buffer solution in the pH range 7.0‐11.0. The electrochemical behavior of PMR modified electrodes was investigated by cyclic voltammetry in Britton Robinson buffer solution at different pHs from 5.0 to 10.0 and found that the best PMR film formation was obtained at pH 9.0. Uric acid was quantitatively determined at PMR modified electrodes by cyclic voltammetry and differential pulse voltammetry in Britton Robinson buffer at pH 5.0. Both methods presented a linear dependence between the anodic peak current and the concentration of uric acid in the range of 0.4 to 60 μM and 0.08 to 100 μM with the limits of detection of 0.038 and 0.009 μM for cyclic voltammetry and differential pulse voltammetry, respectively. Poly(methyl red) as redox mediator allowed the determination of uric acid without any interferences from the substances in serum samples.     

Synthesis of Two Novel Rhenium（I） Bipyridyl Photosensitive Dyes

Two novel rhenium(I) 2, 2′-bipyridyl complexes, [(4,4′-di-COOEt-bipy) Re(CO)3 (NCCH3)PF6] and [(4,4′-di-COOEt-bipy) Re (CO)3 (NCS)], a model complex [(4,4′-di-COOEt-bipy) Re (CO)3 (pyridine)PF6], were synthesized. Their ground state electronic spectra and emission spectra were measured in acetonitrile. The MLCT absorption maximum of the complex exhibited a considerable red shift as the ligand changed from pyridine to CNCH3, or SCN.     

Zinc oxide nanoparticles synthesized using Oldenlandia Umbellata leaf extract and their photocatalytic and biological characteristics

The aim of this study was to examine the environmentally friendly green production of zinc oxide nanoparticles (ZnO NPs) utilizing Oldenlandia Umbellata (OU) leaves extract, as well as to study the photo catalytic and biological activities of these particles. XRD, UV-Visible, FT-IR, SEM, EDAX, TEM and Zeta potential studies were used to investigate the purity and properties of as synthesized ZnO NPs. From the FT-IR investigations presenting functional groups were verified. The hexagonal form and wurtzite crystal nature were confirmed by SEM and XRD photographs. The decreasing zeta potential of ?23.7 mV suggested the stability of OU-ZnO NPs, which was validated by Zeta potential and EDAX measurements. The OU-ZnO NPs' photo catalytic activity was also examined using their methylene red dye degradation potential. It also has a DPPH test that revealed it had a 66% radical scavenging activity. Furthermore, this substance was proven to be an effective anti-fungal agent against Candida albicans, which demonstrated a maximum mycelial inhibition of 12.5 ± 0.7. Additionally, the biosynthesized nanoparticles had high antibacterial activity verses all of the microbiological strains tested to varying degrees.     

一种红光发射的粘度荧光探针

以三苯胺和苯并噻唑盐为原料,设计合成了一种具有红光发射特性的D-π-A型荧光粘度探针N-乙酸乙酯基-2-(4-甲酸甲酯基三苯胺-4'-乙烯基)苯并噻唑六氟磷酸盐(L),运用现代分析测试手段进行了系统地表征。 研究结果表明,探针L的最大发射波长为630 nm,能有效地降低生物背景,提高生物成像的信噪比。 该探针对粘度有很好的荧光响应,其荧光强度比值(I/I₀)的对数与粘度的对数呈现很好的线性关系(R²=0.9934)。 此外,探针L对极性的敏感性小,且荧光信号不受生物分子的干扰。 生物学研究结果表明,探针L具有低的细胞毒性,可应用于细胞内微环境粘度的荧光成像。     

A Possibility for Studying Gravitational Properties of the Neutrino

We consider the effect that the gravitational field of a neutrino pulse radiated in the collapse of presupernova nuclei has on the observable optical radiation spectra of atoms at the supernova surface. We show that at the modern level of development of experimental methods, neutrino monitoring supplemented by optical monitoring of supernova candidates provides a unique possibility to check whether the Einstein equivalence principle is satisfied for neutrinos of each of the three types (electron, muon, and tau-lepton) and their antiparticles, to estimate the change of the gravitational potential at the surface of the star at the instant of the neutrino radiation pulse, and to obtain upper limits on the mass values of these neutrinos in a new way.     

催化荧光法测定痕量铜的研究

本文拟定了一个催化荧光法测定痕量铜的新方法,确定了该催化反应的速度方程式和反应级数。方法检测限达0.1ng Cu/ml,相对标准偏差为3.7％,具有较好的选择性,可不经分离直接用于头发样品中铜的测定,回收及对照实验结果令人满意。     

水热法制备的NaEu(MoO4)2-x(WO4)x固溶体微晶及其发光特性

采用水热法制备了NaEu(MoO4)2-x(WO4)x固溶体微晶; 通过X射线衍射(XRD)、扫描电镜(SEM)和荧光分析(FA)对所制备的微晶进行了表征。XRD结果表明NaEu(MoO4)2-x(WO4)x微晶呈现典型的四方晶相白钨矿结构。SEM分析表明微晶呈米粒状。荧光分析显示, NaEu(MoO4)2-x(WO4)x微晶在370～386 nm之间呈现MO2-4 配离子(M=Mo,W)的特征发射峰, 发射波长随x的增大而减小; 同时, Eu3+在592 nm(5D0→7F1)和614 nm(5D0→7F2)的特征发射峰均明显显现, 强度随x的增大而逐渐增大。     

Modification of carbon paste with congo red supported on multi-walled carbon nanotube for voltammetric determination of uric acid in the presence of ascorbic acid

A chemically modified carbon-paste electrode (CPE) is prepared by incorporating congo red (CR) immobilized on multi-walled carbon nanotube (MWCNT). The results show that CR is effectively immobilized on the surface of MWCNT under the ultrasonic agitation in aqueous solution and further incorporating the nafion. The prepared electrode, due to the electrostatic repulsions between the CR and ascorbate anion, is capable to mask the response of the ascorbic acid (AA) completely and provide an effective method for the detection of minor amounts of uric acid (UA) in the presence of high concentrations of AA. On the other hand, an increase in the microscopic area of the electrode by addition of MWCNT together with the electrocatalytic activity caused to a significant enhancement in the voltammetric response to UA. Optimization of the amounts of composite modifier in the matrix of CPE is performed by cyclic and differential pulse voltammetric measurements. The modified electrode shows a linear response to UA in the range of 1.0 × 10⁻⁷–1.0 × 10⁻⁴ M with a detection limit of 1.0 × 10⁻⁸ M. The electrode exhibits excellent accuracies for the determination of UA in the presence of high concentrations of AA (a recovery of 97.6%). The response of the electrode toward sulfhydryl compounds such as cysteine, penicillamine, and glutathione is not considerable. This reveals a good selectivity for the voltammetric response toward UA. The effective electrocatalytic property, ability for masking the voltammetric responses of the other biologically reducing agents, ease of preparation, and surface regeneration by simple polishing together with high reproducibility and stability of the responses make the modified electrode suitable for the selective and sensitive voltammetric detection of sub-micromolar amounts of UA in clinical and pharmaceutical preparations.     

溶剂对光致变色材料-乙基红的光学特性影响

研究了溶剂性质对光致变色材料乙基红光学性质的影响.用吸收谱测定了乙基红染料在不同溶剂中的溶剂化位移.对相同浓度多种乙基红溶液进行了Z-scan测量,测量了不同乙基红溶液的光限幅效应,并讨论了其与溶剂之间的关系.随极性增加,吸收谱蓝移,可以通过选择不同溶剂,改变非线性材料的应用窗口.实验结果表明,在连续光照射下,乙基红溶液的非线性折射主要由热效应引起,非线性折射系数n2受溶剂的热学性质影响较大.此外,Z-scan结果中的非线性吸收为饱和吸收.至于光限幅效应,主要受热效应影响,但亦可由吸收谱预测出在某波长处的动态范围.得出的结论有助于偶氮染料作为非线性材料的应用.     

Application of Chimera grid to modelling cell motion and aggregation in a narrow tube

A computational scheme using the Chimera grid method is presented for simulation of three‐dimensional motion and aggregation of two red blood cells (RBCs) in a narrow tube. The cells are modelled as rigid ellipsoidal particles; the computational scheme is applicable to deformable fluid‐filled particles. Attractive energy between two RBCs is modelled by a depletion interaction theory and used for simulating aggregation of two cells. Through the simulation, we show that the Chimera grid method is applicable to the simulation of three‐dimensional motion and aggregation of multiple RBCs in a microvessel and microvascular network. Copyright © 2006 John Wiley & Sons, Ltd.