Two New C—21 Steroidal Glycosides from Cynanchum aurichulatum

Two new C-21 steroidal glycosides, cynanauriculoside I and cynanauriculoside Ⅱ, were isolated from the roots of Cynanchum aurichulatum. Their structures were established using spectroscopic methods including one and two-dimensional NMR.     

A 3-D noninterpenetrating diamondoid network of a decanuclear copper(I) complex

The solvothermal reaction of CuCl(2).2H(2)O with pyridine-4-thiol and ethanol yielded a novel photoluminescent 3-D polymeric complex with an interesting decorated diamondoid network that is constructed of decanuclear copper(I) cluster units and mu(4)-Cl ligands. The in situ generation of CuSO(4).5H(2)O implies the spontaneous occurrence of desulfurization and redox reactions in the present system.     

Influence of the preparation procedure on the properties of polyaniline based magnetic composites

A versatile process for the preparation of composite films consisting of magnetite (Fe₃O₄) nanoparticles embedded in a polyaniline (PANI) matrix is reported. Spectroscopic properties of polyaniline matrix (PANI-EB), polyaniline protonated with camphor sulfonic acid (PANI-CSA_0.5) PANI-ES and PANI/Fe₃O₄-CSA_0.5 composites were studied, both in the state of the solutions of m-cresol and in thin films processed from the same solvents. The results of these studies indicate that m-cresol can be used for PANI/Fe₃O₄ composite preparation. Such films show both reasonably high electrical conductivity and magnetic permeability. A controlled application of a magnetic field during the casting process resulted in the formation of the materials with an unusual combination of magnetic and transport properties. The obtained films show the behavior that can be explained by the presence of both ferromagnetic and paramagnetic phases. The superparamagnetic contribution, if any, is very small. Application of the external magnetic field during fabrication of the composites stimulates creation of the aggregates of magnetic particles which, although keeps conductivity at a relatively high level, leads to a small decrease of the conductivity value.     

Direct electron transfer reaction of glucose oxidase at bare silver electrodes and its application in analysis

The direct electron transfer reaction of glucose oxidase (GOx) at a bare silver electrode is verified. The electron transfer number n = 2, electron transfer coefficient α = 0.45 and rate constant of the electrochemical reaction K_s = 0.1 s⁻¹ are obtained. This communication presents a multimolecular adsorption model to explain the properties of the direct electron reaction between GOx and bare silver electrodes. The residual valence force may be an important factor to ensure a direct electron transfer reaction on the bare electrode. On the basis of the experimental fact that only biologically active GOx exhibits electrochemical activity in solution, a facile analytical method for analyzing the active GOx concentration is developed. The results determined correspond very well to that of a spectrometric method.     

Labile rhizosphere soil solution fraction for prediction of bioavailability of heavy metals and rare earth elements to plants

A labile rhizosphere soil solution fraction has been recommended to predict the bioavailability of heavy metals and rare earth elements to plants. This method used moist rhizosphere soil in combination with a mixture of 0.01 mol L(-1) of low-molecular-weight organic acids (LMWOAs) as extractant. The extracted soil solutions were fractionated into two colloidal fractions of <0.45 microm (F(3)) and <0.2 microm (F(2)), and one truly dissolved fraction including free metal ions and inorganic and organic complexes (fractionr(0.2 microm, LMWOAs) approximately r(0.45 microm, LMWOAs). In the case of rare earth elements the good correlation was obtained for both the wheat roots and shoots. Generally, the correlation coefficients obtained by LMWAOs were better than that obtained by the first step of BCR method. Therefore, LMWAOs and F(lrss) were strongly recommended to predict the bioavailability of metals in soil pools to plants.     

α''-取代磺酰基-α,β-不饱和酮的不对称催化环加成反应的研究

在手性金属钛配合物催化剂存在下，研究了α′－取代磺酰基－α，β－不饱和酮的不对称催化环加成反应；讨论了α，β－不饱和酮各种取代磺酰基对反应活性和对映选择性的影响；高收率地合成了高光学纯度的环加成产物，并对环加成产物的构型进行了鉴定。     

镓改性ZSM-5沸石中镓活性中心的形成与表征

采用脉冲微反体系研究了经不同程度还原和不同镓含量的GaZSM-5沸石的芳构化性能与吡啶吸附红外光谱特征谱带吸收度的关联，证实了1458 cm~(-1)吸收带的用于表征与Ga物种有关的活性中心，并研究了沸石的硅铝比对Ga中心形成和Ga的价态对芳构化性能的影响。结果表明，对Ga含量相同的样品来说，硅铝比愈低，起始Ga中心生成量愈多，高价态与低价态的Ga中心对丙烷芳构化反应都有促进作用。     

Development of ELISA and immunochromatographic assay for ofloxacin

Two rapid,sensitive and reliable immunoassay methods,namely competitive indirect enzyme-linked immunosorbent assay(CI- ELISA)and colloidal gold-based immunochromatographic assay(CGIA),were developed to detect ofloxacin(OFL).The linear range of the CI-ELISAwas from 0.5 to 128 ng/mL with a limit of detection(LOD)of 0.35 ng/mL.Good recoveries were obtained in analyzing simulated swine urine samples.The CGIA could accurately estimate OFL at concentrations as low as 10 ng/mL in less than 10 min,and test results were read visually without any instrument.     

螺［异苯并呋喃－1（3H），9＇－（9H）－2＇－N，N－二苄胺基－6＇－二乙胺基占吨］－酮－3的合成及晶体结构研究

合成了螺［异苯并呋喃－１（３Ｈ），９＇－（９Ｈ）－２＇－Ｎ，Ｎ－二苄胺基－６＇－二乙胺基占吨］－酮－３，Ｃ＿（３７）Ｈ＿（３４）Ｎ＿２Ｏ＿３，单斜晶系，空间群Ｃｃ，晶体学参数为ａ＝１６．８２６（４），ｂ＝１０．６４８（４），ｃ＝１７．６１８（７），β＝９２．２５（２）°，Ｖ＝３１５４（２），Ｚ＝４，Ｍ＿ｒ＝５６６．７，Ｄ＿ｘ＝１．１９ｇ／ｃｍ３，Ｆ（０００）＝１２００。结构由直接法解出，偏离因子Ｒ＝０．０８０。分子由占吨和异苯并呋喃两部分组成Ｙ形结构，占吨部分相连的苄基的两个苯环位于占吨部分的两侧。     

Interface characteristics in diffusion bonding of Fe3Al with Cr18-Ni8 stainless steel

Fe3Al and Cr18-Ni8 stainless steel were diffusion-bonded in vacuum and a Fe3Al/Cr18-Ni8 interface with reaction layer was formed. Microstructure in the reaction layer at Fe3Al/Cr18-Ni8 interface was analyzed by means of scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). The growth of reaction layer with heating temperature (T) and holding time (t) was researched. The results indicate that FeAl, Fe3Al, Ni3Al, and alpha-Fe (Al) solid solution are formed in the reaction layer. These phases are favorable to promote the element diffusion and to accelerate the formation of the reaction layer at Fe3Al/Cr18-Ni8 interface. The growth of reaction layer obeys the parabolic law and its thickness (X) is expressed by X2 = 7.5 x 10(-4)exp(-83.59/RT)(t - t0).