基于折反射原理的层去反求技术研究

为了克服传统层去反求测量中图像衬比度较低的缺陷,提出一种新的基于棱镜反射原理的层去反求图像摄取方法。该方法利用棱镜的全发射和折射作用提高图像衬比度,根据物体反射率的高低可分别采用垂直照明和倾斜照明,分别可获得高衬比度的亮目标暗背景和暗目标亮背景图像,为了校正由于折反射引入的几何变形,推出了相应的数学变换模型。该研究已成功投入实际产品校正的应用中,研究表明这种新的层去法比起传统的层去法不仅在于图像衬比度高,而且物体截面图像的轮廓更清晰可靠、无需填充反差材料,有望在零件及模型的反求测量中发挥较大的作用。     

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     

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.     

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.     

Speciation of selenomethionine and selenocystine using online micro-column containing Cu(II) loaded nanometer-sized Al2O3 coupled with ICP-MS detection

A flow injection online speciation procedure by using micro-column packed with Cu(II) loaded nanometer-sized Al₂O₃ coupled to inductively coupled plasma mass spectrometry (ICP-MS) for the separation and determination of selenomethionine (SeMet) and selenocystine (SeCys₂) has been developed. The main factors affecting the separation and preconcentration of SeMet and SeCys₂ including pH value, sample flow rate, eluent concentration, eluent volume and flow rate, and interfering ions have been investigated. It was found that SeCys₂ could be selectively retained by micro-column packed with Cu(II) loaded nanometer-sized Al₂O₃ at pH 4.0, and the retained SeCys₂ could be eluted by 1.0 mol L⁻¹ HNO₃, while SeMet was not retained and passed through the micro-column directly at this pH. Both SeMet and SeCys₂ could be quantitatively adsorbed by the micro-column at pH 9.0, and the retained SeMet and SeCys₂ could be easily eluted with 1.0 mol L⁻¹ HNO₃. The content of SeMet was obtained by subtracting the SeCys₂ from the total content of seleno amino acids. With the enrichment factor of 7.8 and 7.7, the limits of detection (LODs) for SeMet and SeCys₂ were found to be 24 pg Se mL⁻¹ and 21 pg Se mL⁻¹, respectively. The relative standard deviations (RSDs) for SeCys₂ and SeMet with seven replicate determinations of 1.0 ng mL⁻¹ SeMet and SeCys₂, were 2.1% and 1.6%, respectively, the sampling frequency of 8 h⁻¹ was obtained. The proposed method was applied to the speciation of SeMet and SeCys₂ in selenized yeast, human urine and serum with satisfactory results.