Synthesis and antiproliferative activity of some ellipticine-like 11H-pyrido[a]carbazole derivatives

Some modified 11H-pyrido[a]carbazoles (11H-PyC) and their corresponding tetrahydro derivatives (11H-THPyC) were prepared. A common multistep pathway characterized by conventional reactions, including a Fischer-indole-type synthesis, yielded the tetracyclic compounds. To improve cytotoxicity, 11H-PyC and 11H-THPyC derivatives were endowed with a diethylaminoethyl side chain. The antiproliferative activity was assessed in three human tumor cell lines, and a number of derivatives showed a cytotoxic effect in agreement with their capacity to form a molecular intercalative complex with DNA and to interfere with the relaxation activity of DNA topoisomerase II. In contrast, three derivatives that exhibited significant antiproliferative efficacy, showed no inhibition of topoisomerase II, thus suggesting an unexpected and novel mode of action for these ellipticine-like compounds independent of topoisomerase II activity.     

Growth Temperature and Salinity Impact Fatty Acid Composition and Degree of Unsaturation in Peanut-Nodulating Rhizobia

Growth and survival of bacteria depend on homeostasis of membrane lipids, and the capacity to adjust lipid composition to adapt to various environmental stresses. Membrane fluidity is regulated in part by the ratio of unsaturated to saturated fatty acids present in membrane lipids. Here, we studied the effects of high growth temperature and salinity (NaCl) stress, separately or in combination, on fatty acids composition and de novo synthesis in two peanut-nodulating Bradyrhizobium strains (fast-growing TAL1000 and slow-growing SEMIA6144). Both strains contained the fatty acids palmitic, stearic, and cis-vaccenic + oleic. TAL1000 also contained eicosatrienoic acid and cyclopropane fatty acid. The most striking change, in both strains, was a decreased percentage of cis-vaccenic + oleic (≥80% for TAL1000), and an associated increase in saturated fatty acids, under high growth temperature or combined conditions. Cyclopropane fatty acid was significantly increased in TAL1000 under the above conditions. De novo synthesis of fatty acids was shifted to the synthesis of a higher proportion of saturated fatty acids under all tested conditions, but to a lesser degree for SEMIA6144 compared to TAL1000. The major adaptive response of these rhizobial strains to increased temperature and salinity was an altered degree of fatty acid unsaturation, to maintain the normal physical state of membrane lipids.     

信息与动态

甲醇合成催化剂保护剂实现国产化　　甲醇合成催化剂保护剂能有效地脱除原料气中羰基铁、镍 ,延长甲醇合成催化剂寿命 ,降低粗甲醇中的杂质含量 ,具有精脱硫和脱除羰基铁、镍的双重功能。由齐鲁石化公司研究院研制开发的ＱＸＪ- 0 1和ＱＭＧ - 0 1甲醇合成催化剂保护剂分别于 2 0 0 0年和 2 0 0 1年在齐鲁石化第二化肥厂1 0万ｔ/ａ甲醇上实现国产化 ,综合性能分别达到德国南方化学公司的Ｋ30 6和丹麦托普索公司的ＭＧ90 1水平。(王冬梅　周广林 )轴径向变换反应器实现国产化　　轴径向变换反应器由瑞士卡萨尔公司首先实现工业化 ,在中国已有…     

A preconcentration system for determination of copper and nickel in water and food samples employing flame atomic absorption spectrometry

A separation/preconcentration procedure using solid phase extraction has been proposed for the flame atomic absorption spectrometric determination of copper and nickel at trace level in food samples. The solid phase is Dowex Optipore SD-2 resin contained on a minicolumn, where analyte ions are sorbed as 5-methyl-4-(2-thiazolylazo) resorcinol chelates. After elution using 1 mol L(-1) nitric acid solution, the analytes are determinate employing flame atomic absorption spectrometry. The optimization step was performed using a full two-level factorial design and the variables studied were: pH, reagent concentration (RC) and amount of resin on the column (AR). Under the experimental conditions established in the optimization step, the procedure allows the determination of copper and nickel with limit of detection of 1.03 and 1.90 microg L(-1), respectively and precision of 7 and 8%, for concentrations of copper and nickel of 200 microg L(-1). The effect of matrix ions was also evaluated. The accuracy was confirmed by analyzing of the followings certified reference materials: NIST SRM 1515 Apple leaves and GBW 07603 Aquatic and Terrestrial Biological Products. The developed method was successfully applied for the determination of copper and nickel in real samples including human hair, chicken meat, black tea and canned fish.     

Arsenic removal from high-arsenic water by enhanced coagulation with ferric ions and coarse calcite

Arsenic removal from high-arsenic water in a mine drainage system has been studied through an enhanced coagulation process with ferric ions and coarse calcite (38-74 microm) in this work. The experimental results have shown that arsenic-borne coagulates produced by coagulation with ferric ions alone were very fine, so micro-filtration (membrane as filter medium) was needed to remove the coagulates from water. In the presence of coarse calcite, small arsenic-borne coagulates coated on coarse calcite surfaces, leading the settling rate of the coagulates to considerably increase. The enhanced coagulation followed by conventional filtration (filter paper as filter medium) achieved a very high arsenic removal (over 99%) from high-arsenic water (5mg/l arsenic concentration), producing a cleaned water with the residual arsenic concentration of 13 microg/l. It has been found that the mechanism by which coarse calcite enhanced the coagulation of high-arsenic water might be due to attractive electrical double layer interaction between small arsenic-borne coagulates and calcite particles, which leads to non-existence of a potential energy barrier between the heterogeneous particles.     

辽西低凸起油气成藏的主要控制因素及勘探潜力

从油藏描述入手,结合地质、地震与钻井资料,系统地分析了辽西低凸起油气成藏的主要控制因素。综述了辽西低凸南段、中段、北段的构造演化史、沉积发育、油气运移史、油富集层位和油气运移通道组合。将辽西低凸起东西向分为凸起主体,东侧斜坡带和油气运移通道组合。将辽西低凸起东西向分为凸地卢主体,东侧斜坡带和西侧陡坡带,并分析了相应的圈闭类型及油藏。研究认为,其东侧作以露与反向断层相关的潜山－披覆背斜、半背斜及鼻状－岩性圈闭是今后油气勘探的重要目标。     

Evaluation of batch adsorption of chromium ions on natural and crosslinked chitosan membranes

Removal of chromium ions from aqueous solutions by using natural and crosslinked chitosan membranes was achieved using batch adsorption experiments. The effect of pH (6.0 and 2.0), concentration of chromium ions and crosslinking agents (glutaraldehyde: GLA and epichlorohydrin: ECH) on the adsorption properties of chitosan membranes was analyzed. The experimental equilibrium data was fitted to Langmuir and Freundlich models. Through the model curves, it was possible to observe that the amount of chromium ions adsorbed was significantly higher for crosslinked membranes compared to non-crosslinked chitosan. The maximum adsorbed amount was about 1400 mg g(-1) for ECH-crosslinked chitosan at pH 6.0. The adsorption rates for crosslinked chitosan membranes with glutaraldehyde and epichlorohydrin were similar for natural chitosan. Desorption study using NaCl (1 mol L(-1)) solution was performed on chitosan membranes, in order to recover chromium ions and to determine the suitable number of cycles for repeated use of these membranes without considerable decrease in their adsorption capacity. The desorption results showed that chromium ions could be more effectively removed at pH 2.0 than pH 6.0, mainly for ECH-crosslinked chitosan.     

利用光束偏移技术使显微镜分辨率超出瑞利分辨极限

新近问世的两个荧光显微系统声称其所达到的分辨率已突破瑞利分辨极限。这两个系统工作时运用两束聚焦于样品上的偏移光束,并成像于光重叠区域。本文介绍一个与之相类似的系统,其工作方式也相近,但不用荧光,对这些系统的成像性能进行分析后,作者发现尽管它们的分辨率都有所改进,但关键的是光波带宽并未得到增加。尽管这些系统应用效果良好,并且其工作方式与光瞳面滤光器相似,但这些系统仅只衰减了空间频率,值得鉴赏的是,与以前的论文内容相反,这两系统都未提及真正的超限分辨率这一点重要。