Poly­[[bis(1H‐benz­imidazole‐κN3)cadmium(II)]‐μ‐aqua‐μ‐succinato‐κ2O1:O4]

The title compound, [Cd(C₄H₄O₄)(C₇H₆N₂)₂(H₂O)]_n, is a three‐dimensional polymeric complex. The Cd^II atom is located on an inversion centre and assumes an elongated octahedral coordination geometry, with a long Cd—O distance of 2.5381 (5) Å to the coordinated bridging water molecule. The succinate dianion, located on another inversion centre, bridges adjacent Cd atoms to form succinate‐bridged polymeric chains. The coordinated water mol­ecule is located on a twofold axis and links adjacent succinate‐bridged chains to form a water‐bridged polymeric chain.     

工程结构支撑条件优化设计

提出了一种将结构支撑位置和支撑类型作为设计变量的优化设计方法,就支撑条件改变对结构受力的影响进行了分析,论述了如何在遗传算法中实现结构支撑位置和支撑类型的优化．并通过数值算例说明了结构支撑条件的转变对结构的影响,证明结构支撑条件的优化处理对提高结构性能是有效的．     

20(S)-O-喜树碱肉桂酸酯衍生物的合成及其抗肿瘤活性研究

为了提高喜树碱内酯环的稳定性降低其毒性, 增加其抗肿瘤效能, 以喜树碱为先导化合物, 通过酯化反应直接合成了17个20(S)-喜树碱肉桂酸酯衍生物, 并采用MTT法测定了对于人胃癌细胞SGC-7901的体外抗肿瘤活性, 活性测试结果表明有些化合物的抑制活性明显高于母体化合物喜树碱.     

Extraction of Co-Products from Biomass: Example of Thermal Degradation of Silymarin Compounds in Subcritical Water

In an effort to increase revenues from a given feedstock, valuable co-products could be extracted prior to biochemical or thermochemical conversion with subcritical water. Although subcritical water shows significant promise in replacing organic solvents as an extraction solvent, compound degradation has been observed at elevated extraction temperatures. First order thermal degradation kinetics from a model system, silymarin extracted from Silybum marianum, in water at pH 5.1 and 100, 120, 140, and 160 °C were investigated. Water pressure was maintained slightly above its vapor pressure. Silymarin is a mixture of taxifolin, silichristin, silidianin, silibinin, and isosilibinin. The degradation rate constants ranged from 0.0104 min⁻¹ at 100 °C for silichristin to a maximum of 0.0840 min⁻¹ at 160 °C for silybin B. Half-lives, calculated from the rate constants, ranged from a low of 6.2 min at 160 °C to a high of 58.3 min at 100 °C, both for silichristin. The respective activation energies for the compounds ranged from 37.2 kJ/gmole for silidianin to 45.2 kJ/gmole for silichristin. In extracting the silymarin with pure ethanol at 140 °C, no degradation was observed. However, when extracting with ethanol/water mixtures at and 140 °C, degradation increased exponentially as the concentration of water increased. An erratum to this article can be found at     

Synthesis and characterization of a series of modified polyacrylamide

We present the synthesis and the characterization of a new class of modified polyacrylamides (MPAM) with the unusual trait of strong emulsification ability, viscosity enhancement capacity, and significant salt tolerance. Besides, the synthesized polymers have the peculiar aggregation behaviors in aqueous solution. The synthesis was carried out by polymerizing the monomers such as acrylamide (AM), acrylic acid (AA), unsaturated amphiphilic functional moieties, and high steric hindrance functional units. Their aggregation behaviors were investigated by using a scanning electron microscope (SEM). The emulsion, formed by 10 ml of MPAM (with the polymer concentration of 1,000 mg/L) and the 10 ml of crude oil, was very stable, which indicates that the synthesized polymers have unique emulsification properties. The strong hydrophobic interaction between molecules and the three-dimensional network formed in aqueous solution were exhibited by the experimental results of steady fluorescence and SEM experiments. It could be concluded that the performance of polymers for enhanced oil recovery (EOR) can be remarkably enhanced by introducing functional monomers to polymer backbone, which allows the new class of modified polymers to have more promising application in enhanced oil recovery.     

Thermokinetic studies of the groups on TiO2 surface

The properties of groups on TiO₂ surface were evaluated by infrared (IR) spectra and thermal analysis. It could be found that water and ethanol are removed mainly between 343 and 363 K and the process is accompanied by an endothermic change. The results also show that ethanol could be removed completely below 673 K and the physically bonded or hydrogen‐bonded water could be removed almost completely above 873 K. The exothermic peaks ranging from 573 to 773 K are caused by the changes that chemisorbed water (Ti‐O‐H) on the surface condenses and evolves into water. There appears broad and unstable endothermic process in all temperature ranges due to the adhesions or transformations among the crystal particles. Thermogravimetry (TG) results show that with heat treatment at increasing temperatures, the groups on TiO₂ surface decreases gradually. The half peak breadth of X‐ray diffractometer (XRD) results suggest that TiO₂ crystallize better with higher temperature calcination. The photo‐catalytic efficiency was evaluated by UV‐Vis spectrophotometer. TiO₂ with heat treatment at higher temperature shows more effective photo‐catalytic property. Copyright © 2009 John Wiley & Sons, Ltd.     

Formal syntheses of (±)-Asterisca-3(15),6-diene and (±)-Pentalenene using Rh(I)-catalyzed [(5+2)+1] cycloaddition

Efficient formal syntheses of (±)-Asterisca-3(15),6-diene, a natural product with a bicyclo[6.3.0]undecane skeleton, and (±)-Pentalenene, a natural product with a tricyclo[6.3.0.0^4,8]undecane skeleton, have been achieved by using Rh(I)-catalyzed [(5+2)+1] cycloaddition. The [(5+2)+1] reaction provides an expeditious approach to reach the bicyclic cyclooctenone 4, which was quickly transformed (via hydroboration then oxidation) to diketone 14, a key advanced intermediate for the total synthesis of (±)-Asterisca-3(15),6-diene. Through further transformations, 14 was converted to diene 18, an advanced intermediate for the total synthesis of (±)-Pentalenene.     

Novel naphthalimide derivatives with near-infrared emission: synthesis via photochemical cycloaromatization, fluorescence in solvents and living cell

In this Letter, a pair of novel naphthalimide derivatives with long-wavelength emission (>600 nm) and larger Stokes shift (>140 nm) have been developed through the photochemical cycloaromatization, in which intramolecular radical-induced 1,3-aromatic hydrogen transfer might be occurred. Cell uptake experiments showed that dye 2 could be used as a potential NIR fluorescence imaging agent.     

Two new triterpenes from Duchesnea indica

Two new triterpenes,2α,3β-dihydroxyurs-12-en-18,19-epoxy-28-oic acid(1)and 18,19-seco,2α,3α-dihydroxyl-19-oxo-urs-11, 13(18)-dien-28-oic acid(2)were isolated from the herbaceous part of Duchesnea indica.Their structures were elucidated by spectroscopic analysis,including 2D NMR technique.The isolated compounds exhibited moderate cytotoxic activities against HeLa and L929 cell lines.     

Quality evaluation of Rhizoma Belamcandae (Belamcanda chinensis (L.) DC.) by using high-performance liquid chromatography coupled with diode array detector and mass spectrometry

A high-performance liquid chromatography coupled with diode array detector and mass spectrometry (HPLC-DAD-MS) method was developed to evaluate the quality of Rhizoma Belamcandae (Belamcanda chinensis (L.) DC.) through establishing chromatographic fingerprint and simultaneous determination of seven phenolic compounds. The analysis was achieved on an Alltima C(18) analytical column (250 mm x 4.6 mm i.d. 5 microm) using linear gradient elution of acetonitrile-0.1% trifluoroacetic acid. The correlation coefficients of similarity were determined from the HPLC fingerprints, and they shared a close similarity. By using an online APCI-MS/MS, twenty phenols were identified. In addition, seven of these phenols including mangiferin, 7-O-methylmangiferin, tectoridin, resveratrol, tectorigenin, irigenin and irisflorentin were quantified by the validated HPLC-DAD method. These phenols are considered to be major constituents in Rhizoma Belamcandae, and are generally regarded as the index for quality assessment of this herb. This developed method by having a combination of chromatographic fingerprint and quantification analysis could be applied to the quality control of Rhizoma Belamcandae.