α－氧代烯酮环二硫代缩醛化学α，α－二氧代烯酮环二硫代缩醛与丁酮成环反应

α－氧代烯酮环二硫代缩醛化学α，α－二氧代烯酮环二硫代缩醛与丁酮成环反应朱再明（辽宁师范大学化学系，大连，１１６０２９）刘群（东北师范大学化学系，长春，１３００２４）胡皆汉（中国科学院大连化学物理研究所，大连，１１６００１）α－氧代烯酮环二...     

超临界CO_2萃取-分子蒸馏对大蒜化学成分的提取与分离

采用超临界CO2流体萃取技术和分子蒸馏对大蒜化学成分进行萃取与分离，用气相色谱－质谱联用技术测定其化学成分；从超临界CO2萃取物中鉴定出16种成分，经分子蒸馏后，得到4种主要成分：二烯丙基二硫、3－乙烯基－1，2－二硫代环己－5－烯、2－乙烯基－1，3－二硫代环己－5－烯及二烯丙基三硫。     

新型5-(4-甲基硫代)吡唑磷酸酯的合成及生物活性研究

合成了12个5－（4－甲基硫代）吡唑磷酸酯及6个5－羟基吡唑新化合物，其结构^1H NMR和MS表征。杀虫，除虫及杀菌等生物活性的测试表明部分化合物具有较好的杀虫，除草或杀菌活性。     

3-(2-氧代环烷基)丙酸与(R)-2-硫代四氢噻唑-4-羧酸乙酯的反应

３－（２－氧代环烷基）丙酸与（Ｒ）－２－硫代四氢噻唑－４－羧酸乙酯的反应李叶芝,田颜清,黄化民（吉林大学化学,长春,１３００２３）关键词（Ｒ）－２－硫代四氢噻唑－４－羧酸乙酯,Ｎ－３－（２－氧代环烷基）丙酰－２－硫代四氢噻唑－４－羧酸乙酯,环合反应,...     

腺苷环甘油磷脂缀合成的合成及性质研究

以碘活化的六乙基亚磷酰三胺为磷酰化及环化试剂，经一锅法合成并分离得到硫代环磷酸酯的两个非对映异构体，并对这两个非对映异构体的性质进行了研究。     

α—氧代烯酮环二硫代缩酮化学：α,α—二氧代烯酮环二硫代缩酮与乙二…

由α，α－二氧代烯酮环二硫代缩酮与乙二胺反应制得五种α，α－二氧代烯酮环二氮代缩酮化合物，所有产物均经元素分析，ＩＲ＾１ＨＮＭＲ和＾１３ＣＮＭＲ确证。     

α-氧代烯酮环二硫代缩酮化学——α,α-二氧代烯酮环二硫代缩酮与乙二胺反应

由α，α－二氧代烯酮环二硫代缩酮与乙二胺反应制得五种α，α－二氧代烯酮环二氮代缩酮化合物，所有产物均经元素分析、ＩＲ、１ＨＮＭＲ和１３ＣＮＭＲ确证。     

硫（硒）代磷酸酯—膦酸酯类化合物除草活性的构效关系

利用与自由能有关的取代基物理化学参数，考察了硫（硒）代磷酸酯－膦酸酯类化合物对除草活性的相关性．根据Ｈａｎｓｃｈ方程及多元回归分析，进行了结构与活性定量关系的研究，建立了较好的结构与活性相关式．     

硫代四配位磷化物与邻氨基酚反应

在三乙胺存在下,多种硫代磷酰二氯与邻氨基酚反应,经磷硫双键断开并以σ键与磷相连的基团被置换下来等过程,最终生成双环五配位磷化物.苯基硫代环膦酸酯与邻氨基酚反应分别生成螺环五配位磷化物.苯氧基或烷氧基硫代环磷酸酯与邻氨基酚反应,除磷硫键断裂以及苯氧基、烷氧基被置换外,还发生邻亚氨基苯氧基与邻苯二氧基进行相互交换反应.这些反应机理依据磷原子的电负性,氢质子的活泼性以及P-X键的稳定性进行了讨论.     

腺苷环甘油磷脂缀合物的合成及性质研究

以碘活化的六乙基亚磷酰三胺为磷酰化及环化试剂,经一锅法合成并分离得到硫代环磷酸酯的两个非对映异构体,并对这两个非对映异构体的性质进行了研究.     

Heats of Mixing of Mixed Solvent Solutions of Alkali Metal Salts of Substituted Benzenesulfonic Acids

The enthalpy change on mixing solutions of methyl-substituted benzenesulfonic acids and their salts, with salts having a common cation or anion, at constant ionic strength in mixtures of 1,4-dioxane with water, were measured at 25°C. The heat effects of mixing solutions having a common anion increase almost linearly with the reciprocal value of the dielectric constant of the solvent. The heat effects of mixing solutions having a common cation, which are all negative in water-rich solutions, become endothermic after a certain value of the dielectric constant is passed. The results are discussed in terms of the solute-solvent structural properties. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of reprocessing of oxobiodegradable and non-degradable polyethylene on the durability of recycled materials

The use of plastics is steadily increasing in our daily lives, and plastics are the fastest-growing component of the waste stream. Although the efficiency of plastic recycling is increasing, plastics are often seen as a permanent environmental problem because of littering. The introduction of oxobiodegradable polyolefins (OBDs), containing prodegradant additives, is considered to be a way to reduce this problem by enabling the fast degradation of plastics in the environment. The prodegradant additives form radicals that attack the polymer chains, causing chain scissions and generation of low molecular mass oxidation products that can be consumed by microorganisms. There is, however, a concern that the prodegradant additives will present a problem if OBD materials end up in the conventional plastic recycling streams. The present study therefore highlights the impact of mixing OBD materials with conventional polyolefins to evaluate the impact on the remaining service life of the recyclates.The study included the use of two different OBDs, mixed in different proportions (10% and 20%) in a conventional polyethylene. The remaining service life of the mixtures was evaluated by monitoring the reduction in tensile strain after exposure to thermo-oxidative degradation at 70 °C, compared with a pure polyethylene. The impact of stabilizer content in the mixtures was also evaluated together with the effect of mixing partially degraded OBDs into the recyclate.The results show that the incorporation of minor fractions of OBD materials in the existing recycling streams will not create a severe effect on the service life of the recyclates as long as the polymer mixture possesses a reasonable degree of stabilization.     

HPLC study of tissue distribution of loganin in rats

A rapid, sensitive and selective high performance liquid chromatography (HPLC) method was developed and validated for determination of loganin in rat tissues. Samples were prepared based on a simple protein precipitation. Separation of loganin was achieved on a reversed-phase C(18) column (250 x 4.6 mm, 5 microm) with a mobile phase consisting of acetonitrile and water (16:84, v/v) at a flow rate of 1.0 mL/min. The detection wavelength was set at 236 nm and the temperature of the column was kept at 30 degrees C. The method was applied to study tissue distribution of loganin in rats after a single administration of loganin at a dose of 20 mg/kg. The highest level was observed in kidney, then in stomach, lung and small intestine. The lowest level was found in brain. The peak levels were attained at 90 min in most tissues. It was indicated that kidney was the major distribution tissue of loganin in rats, and that loganin had difficulty in crossing the blood-brain barrier. It was also found there was no long-term accumulation of loganin in rat tissues.     

Performance comparison of three types of high-speed counter-current chromatographs for the separation of components of hydrophilic and hydrophobic color additives

The performance of three types of high-speed counter-current chromatography (HSCCC) instruments was assessed for their use in separating components in hydrophilic and hydrophobic dye mixtures. The HSCCC instruments compared were: (i) a J-type coil planet centrifuge (CPC) system with a conventional multilayer-coil column, (ii) a J-type CPC system with a spiral-tube assembly-coil column, and (iii) a cross-axis CPC system with a multilayer-coil column. The hydrophilic dye mixture consisted of a sample of FD&C Blue No. 2 that contained mainly two isomeric components, 5,5'- and 5,7'-disulfonated indigo, in the ratio of ～7:1. The hydrophobic dye mixture consisted of a sample of D&C Red No. 17 (mainly Sudan III) and Sudan II in the ratio of ～4:1. The two-phase solvent systems used for these separations were 1-butanol/1.3M HCl and hexane/acetonitrile. Each of the three instruments was used in two experiments for the hydrophilic dye mixture and two for the hydrophobic dye mixture, for a total of 12 experiments. In one set of experiments, the lower phase was used as the mobile phase, and in the second set of experiments, the upper phase was used as the mobile phase. The results suggest that: (a) use of a J-type instrument with either a multilayer-coil column or a spiral-tube assembly column, applying the lower phase as the mobile phase, is preferable for separating the hydrophilic components of FD&C Blue No. 2; and (b) use of a J-type instrument with multilayer-coil column, while applying either the upper phase or the lower phase as the mobile phase, is preferable for separating the hydrophobic dye mixture of D&C Red No. 17 and Sudan II.     

Synthesis and Preliminary Anticancer Activity Assessment of N-Glycosides of 2-Amino-1,3,4-thiadiazoles

The addition of 2-amino-1,3,4-thiadiazole derivatives with parallel iodination of differently protected glycals has been achieved using a double molar excess of molecular iodine under mild conditions. The corresponding thiadiazole derivatives of N-glycosides were obtained in good yields and anomeric selectivity. The usage of iodine as a catalyst makes this method easy, inexpensive, and successfully useable in reactions with sugars. Thiadiazole derivatives were tested in a panel of three tumor cell lines, MCF-7, HCT116, and HeLa. These compounds initiated biological response in investigated tumor models in a different rate. The MCF-7 is resistant to the tested compounds, and the cytometry assay indicated low increase in cell numbers in the sub- G1 phase. The most sensitive are HCT-116 and HeLa cells. The thiadiazole derivatives have a pro-apoptotic effect on HCT-116 cells. In the case of the HeLa cells, an increase in the number of cells in the sub-G1- phase and the induction of apoptosis was observed.     

Startup of electrophoresis in a suspension of colloidal spheres

The transient electrophoretic response of a homogeneous suspension of spherical particles to the step application of an electric field is analyzed. The electric double layer encompassing each particle is assumed to be thin but finite, and the effect of dynamic electroosmosis within it is incorporated. The momentum equation for the fluid outside the double layers is solved through the use of a unit cell model. Closed‐form formulas for the time‐evolving electrophoretic and settling velocities of the particles in the Laplace transform are obtained in terms of the electrokinetic radius, relative mass density, and volume fraction of the particles. The time scale for the development of electrophoresis and sedimentation is significantly smaller for a suspension with a higher particle volume fraction or a smaller particle‐to‐fluid density ratio, and the electrophoretic mobility at any instant increases with an increase in the electrokinetic particle radius. The transient electrophoretic mobility is a decreasing function of the particle volume fraction if the particle‐to‐fluid density ratio is relatively small, but it may increase with an increase in the particle volume fraction if this density ratio is relatively large. The particle interaction effect in a suspension on the transient electrophoresis is much weaker than that on the transient sedimentation of the particles.     

Micromechanical modeling of the tensile behavior of oriented polyethylene

The stacked lamellar morphology commonly found in extruded semicrystalline materials has a strong influence on the flow direction, with respect to the loading direction, and on the stability and localization phenomena in tensile experiments. A multiscale numerical model was used to simulate the effect on the macroscopic behavior of a stacked lamellar microstructure. The model established a link between the microscopic, the mesoscopic, and the macroscopic levels. The constitutive properties of the material were identified for the crystallographic and amorphous domains. The average fields of an aggregate of individual phases, having preferential orientations, formed the constitutive behavior of the extruded material. The microscopic morphology of the extruded high‐density polyethylene is based on wide‐angle X‐ray diffraction experiments. The macrostructure was described by a finite element model. The microstructure‐induced deformation hardening in the extrusion direction was found to stabilize the macrostructure when it was loaded in the flow direction. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2983–2994, 2004     

镨叶绿素a分子结构的确定

通过合成镨叶绿素a(Pr-Chla)研究了稀土在叶绿素中的结合方式.Pr-Chla的紫外可见光谱(UV-Vis)、红外光谱(FTIR)证实镨离子已配位到叶绿素a的卟啉环上.其磁圆二色谱(MCD)在Soret带具有双层夹心卟啉的特征结构;通过扩展X射线吸收精细结构谱(EXAFS),采用双层夹心结构模型拟合,确定了Pr周围的近邻结构.表明合成镨叶绿素a具有双层夹心结构.Pr(Ⅲ)夹于两个卟啉环之间,与上下卟啉环上共8个N原子配位,Pr-N键平均键长0.242nm.     

Acid hydrolysis of carboxymethylcellulose of low degree of substitution

Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position.     

Study of the mechanism of the photoisomerization and photooxidation of bilirubin using a model for the phototherapy of hyperbilirubinemia

Liquid chromatography was employed for a study of photochemical degradation of bilirubin in the complex with human albumin, using a model system in the presence of riboflavin. The concentrations of bilirubin, the photoisomers and biliverdin were monitored. The reaction mechanism was verified using a quantified mathematical model and was represented by a reaction scheme. Photoisomerization is the initial process, followed by photooxidation to degradation products of the tetrapyrrole skeleton, with formation of biliverdin as an intermediate. The blood of newborns that were irradiated for treatment of hyperbilirubinemia was studied for the sake of comparison. The effect of some biochemically important substances was followed, in view of possible inhibition of the processes. The experimental results demonstrate that riboflavin acts as a catalyst, even at the concentrations typical for its occurrence in blood. The results are discussed from the point of view of the mechanism of bilirubin degradation during phototherapy.