Electrochemical reduction and voltammetric determination of metronidazole at a nanomaterial thin film coated glassy carbon electrode

Simple and sensitive electrochemical method for the determination of metronidazole, based on a nanostructured film coated glassy carbon electrode (GCE), is described. Multi-walled carbon nanotubes (MWNT) was dispersed into water in the presence of a hydrophobic surfactant to give very stable and homogeneous MWNT suspension, and a MWNT-film coated GCE was achieved via evaporating solvent. Metronidazole yields a well-defined reduction peak whose potential is −0.71 V at the MWNT-film coated GCE in pH 9.0 Britton-Robinson buffer. Compared with bare GCE, the MWNT-film modified GCE significantly enhances the reduction peak current of metronidazole. All the experimental parameters were optimized for the determination of metronidazole. The detection limit is 6×10⁻⁹ mol/l at 2 min accumulation. This method has been successfully used to determine metronidazole in the drugs. Furthermore, results obtained by the proposed method have been compared with spectrophotometric method.     

Dynamic stereochemistry of hypervalent silicon, germanium and tin compounds containing amidomethyl C, O-chelating ligands

The results of NMR-spectroscopy studies of the structure, dynamic stereochemistry, and intermolecular interactions in solutions of organic derivatives of penta-and hexacoordinated silicon, germanium, and tin containing amidomethyl, lactamomethyl, and related bidentate ligands are surveyed. For the series of works “Dynamic stereochemistry of hypervalent compounds of silicon, germanium, and tin,” the author was awarded the Academia Europea Prize for young scientists from CIS in 1996. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1912–1934. November, 1997.     

Structure of Sol-Gel-Derived Sodium Dititanate Glass

The sodium dititanate, Na₂O·2TiO₂ glass was prepared by the sol-gel method. The structure of the glass, especially local environment of Ti⁴⁺ ions was examined using X-ray diffraction and X-ray absorption fine structure (XAFS) analyses, and was compared with that of the melt-derived glass with the same composition. It was found that Ti⁴⁺ ions are rather in five-fold coordination state, forming TiO₅ pyramids with one doubly bonded Ti=O in the gel-glass, while they were in lower coordination state or four-fold coordination in the melt-derived glass.     

人尿中诺龙和炔诺酮代谢物的气相色谱-质谱分析

本文对合成的19-去甲雄烷醇酮的四个差向异构体混合物进行气相色谱分离,对诺龙和炔诺酮用药后,留取的人尿样通过化学预处理,MSTFA/TMSI衍生化反应,GC/MS分析,确证了尿样中诺龙的两个主要代谢产物为19-去甲雄酮和19-去甲原胆烷醇酮,炔诺酮的两个主要代谢物是四氢炔诺酮(THINE)的两个形式,可能是3α-OH-5α-THINE和3α-OH-5β-THINE,在炔诺酮代谢前期,还发现有诺龙的上述两个代谢物存在。     

Application of thermal analysis to study smelting reduction kinetics

A thermal analysis study on the reduction of iron oxide rich slags under different conditions is presented in this paper. The effects of important process variables such as time, temperature, lime-silica ratio, FeO level in slag etc. are discussed. It is shown that the mechanism of reduction by externally added graphite is different from that by a carbon saturated bath although the activation energy values are similar.     

弹性体型聚氨酯和聚碳酸酯共混物的形态结构

用ＤＳＣ、ＷＡＸＤ和ＳＡＸＳ研究了溶液共混的弹性体型聚氨酯（ＰＵ）／聚碳酸酯（ＰＣ）共混物的结构。结果表明，ＰＵ／ＰＣ为部分相容体系；共混过程中，溶剂ＤＭＦ的诱导作用使ＰＣ形成结晶，其长周期与ＰＵ硬段形成微相的长周期相近     

ICP—AES法测定硼酸铝钇钕（NYAB）激光晶体中的Nd

应用ICP-AES法分析自倍频激光晶体(NYAB)样品中的Nd,在石墨坩埚中于500℃用NaOH熔融分解样品,方法的回收率为96%～105%,测定的相对标准偏差为1.42%,方法简便,可给出满意的分析结果。     

Na_6V_（10）O_（28）·12H_2O的合成与结构

合成并测定了十钒酸盐Ｎａ_６Ｖ_（１０）Ｏ_（２８）·１２Ｈ_２Ｏ的单晶结构。晶体属单斜晶系，Ｐ２_１／ｎ群空间，ａ＝１２．０１９（２），ｂ＝１７．１５４（２），ｃ＝１８．１７８（６），β＝１０６．２９（２）°，Ｖ＝３５７９（１），Ｍ_ｒ＝１２８７．５，Ｆ（０００）＝２５６０，μ＝２５，４４ｃｍ￣（－１），Ｚ＝４，Ｄ_ｃ＝２．３８ｇ·ｃｍ（－３）。结构由重原子法解出，全矩阵最小二乘法修正至Ｒ＝０．０６４，Ｒ_ｗ＝０．０８３。Ｖ_（１０）簇阴离子可以看成由１０个ＶＯ_６变形八面体形成，其中氧原子有４种类型：端氧、二桥氧、三桥氧和六桥氧。结果表明，阳离子相同但结晶水的数目不同时，十钒酸盐的晶系和空间群不同。     

硅钼杂多阴离子薄膜修饰电极线性扫描伏安法测定黑液中可溶性硅

本文报导了以玻碳电极为基体的１：１２硅钼杂多阴离子薄膜化学修铈电极的制备及其电化学特性。并应用于导数伏安法测定。在４．０×１０￣（－３）ｍ０ｌ／Ｌ（ＮＨ＿４）＿６ＭＯ＿７Ｏ＿（２４）－６．８×１０￣（－２）ｍｏｌ／ＬＮａ＿３Ｃｉｔ－０．４８ｍｏｌ／ＬＮＨＯ＿３体系中，硅浓度在８．３×１０￣（－７）～１．７×１０￣（－３）ｍｏｌ／Ｌ范围内与峰电流呈良好线性关系，检测限为８．０×１０￣（－７）ｍｏｌ／Ｌ。对可溶性硅（以ＳｉＯ＿２计）为２４５．０５ｍｇ／Ｌ的黑液，稀释１０倍后，取２．００ｍＬ平行测定９次，ＲＳＤ为０．５８％，加标回收率在９７．３％～１０４．４％间。     

APPLICATION OF CLUSTER ANALYSIS TO THE TAXONOMY OF ORDER AND SUBORDER OF THE TRILOBITA

In the present paper, in accordance with the exoskeleton structure, the method of Q-mode cluster analysis is used for a taxonomic study of 17 orders (suborders) of the Tritobita that was established or adopted by H. J. Harrington (1959), J. Bergstrm (1973), and R. A. Fortey and R. M. Owens (1975). The author suggests that the Trilobita be subdivided into 9 orders and 14 suborders, i. e. order Agnostida Kobayashi, 1935 (suborder Agnostina Salter, 1864 and suborder Eodiscina Kobayashi, 1939), order Redlichiida Richter, 1933 (suborder Redlichiina Richter, 1933, suborder Bathynotina Lochman-Balk, 1959 and suborder Olenellina Resser, 1938), order Corynexochida Kobayashi, 1935, order Ptychopariida Swinnerton, 1915 (suborder Ptychopariina Richter, 1933, suborder Proetina Fortey & Owens, 1975, nom. transl, ex Proetida Fortey & Owens, 1975 and suborder Calymenina Swinnerton, 1915, emended herein), order Illaenida Jaanusson, 1959 (suborder Illaenina Jaanuson, 1959 and suborder Asaphina Salter, 1864, emended herei