Two-dimension fluorescence correlation spectroscopy to characterize the binding of organic ligands with zinc in eutrophic lake

Metal binding of organic ligands can definitely affect its environmental behavior in waters, while information on the binding heterogeneity with different organic ligands is still lacked till now. In this study, the binding of zinc with organic matters associated with cyanobacterial blooms, including dissolved organic matters (DOM) and attached organic matters (AOM), were studied by using fluorescence quenching titration combined with two-dimensional correlation spectroscopy (2D-COS). Metal-induced fluorescent quenching was obviously observed both for DOM and AOM, indicating the formation of metal-ligand complexes. Compared with the one-dimensional spectra, 2D-COS revealed the sequences of metal-ligand interaction with the following orders: 276 nm > 232 nm for DOM and 232 nm > 276 nm for AOM. Furthermore, the modified Stern-Volmer model showed that the binding constant (log KM) of 276 nm in DOM was higher than that of 232 nm (4.93 vs. 4.51), while AOM was characterized with a high binding affinity for 232 nm (log KM: 4.83). The ranks of log KM values were consistent with the sequential orders derived from 2D-COS results both for the two samples. Fluorescence quenching titration combined with 2D-COS was an effective method to characterize the metal-ligand interaction.     

溶胶-凝胶法可控制备氧化锡纳米晶包覆碳纳米管

采用溶胶-凝胶法制备了氧化锡纳米晶包覆的碳纳米管。自由Sn4+离子从稳定的Sn柠檬酸配合物中缓慢释放出来,迁移到碳纳米管上,并在碳纳米管上沉积形成了SnO2纳米晶,沉积过程完全为异相成核方式,在碳纳米管外并没有发现单独的SnO2纳米晶。这种溶胶-凝胶方法还可以用来制备无氯离子污染的、低团聚的纯SnO2纳米晶。     

环糊精-杯芳烃偶合体系研究进展及前景展望

综述了环糊精-杯芳烃偶合体系(cyclodextrin-calix[n]arene)的合成及性质研究的进展, 并对其开发前景进行了展望. 环糊精-杯芳烃偶合体系可以应用于分子识别、主客体化学、水相有机反应、分子催化反应等领域.     

Syntheses and cell-based phenotypic screen of novel 7-amino pyrido[2,3-d]pyrimidine-6-carbonitrile derivatives as potential antiproliferative agents

A series of N-3-substituted 7-aminopyrido[2,3-d]pyrimidin-6-carbonitrile derivatives was readily synthesized and their anti-proliferative activities on five types of tumor cells were evaluated through a cell-based phenotypic screening approach. Compound 3k was found to be potent on human colon cancer SW620 cells with an IC(50) value of 12.5 mM. Structural optimization of compound 3k led to compound 4a with improved anti-proliferative potency on SW620 cells with an IC(50) value of 6.9 mM. Further cell-cycle analyses suggested that compound 4a induced apoptosis of SW620 cells in a concentration-dependent manner.     

多壁碳纳米管/溴/聚苯乙炔三元复合材料导电性能的研究

通过机械共混和溶液共混制备了多壁碳纳米管(MWNTs)/溴/聚苯乙炔(PPA)三元复合材料, 复合材料表现出良好的导电性能, 电导率为10 S/m, 达到掺溴MWNTs的导电水平. 通过固体紫外光谱、XPS和SEM分析了复合材料中MWNTs、溴与PPA三者之间的相互作用, 研究了独立导电单元的形成, 以及导电单元对电导率提高所起的作用. 结果表明, 当MWNTs含量较低时, MWNTs和PPA之间的溴转移导致复合材料电导率降低; MWNTs含量较高时, 独立导电单元的数目增多, 复合材料的电导率随之大幅提高.     

Review and new theoretical perspectives on active disturbance rejection control for uncertain finite-dimensional and infinite-dimensional systems

Nonlinear Dynamics - The active disturbance rejection control (AD RC), first proposed by Jingqing Han in late 1980s, is a powerful control technology being able to deal with external disturbances...     

CH3OH在Ga-Rich GaAs(001)-(4×2)表面上的吸附与解离: 团簇模型的密度泛函计算

采用简单团簇模型结合密度泛函理论研究了CH3OH在Ga-Rich GaAs(001)-(4×2)表面上的吸附与解离过程. 计算结果表明, CH3OH在Ga-Rich GaAs(001)-(4×2)表面上首先会形成两种化学吸附状态, 然后CH3OH经解离生成CH3O自由基和H原子吸附在表面不同位置上. 通过比较各个吸附解离路径, 发现解离后的H原子相对更容易吸附在位于表面第二层紧邻的As原子上.     

Uniform boundness of global solutions for a n-dimensional spherically symmetric combustion model

This paper concerns a n-dimensional spherically symmetric model for the combustion of a viscous, compressible, radiative-reactive gas with a chemical kinetics equation. Under suitable assumptions, we establish some uniform-in-time estimates of global solutions to this model which improve some known results.     

The Effective Permittivity of Reacting Mixture Solutions for Multiphysics Calculations

Huang and Yang (PIER Lett. 5: 99?C107, 2008) proposed a method based on experimental results to calculate the effective permittivity of liquid reacting mixture solutions. The method cannot be directly applied to multiphysics calculations for microwave heating on chemical reactions, because the derived formula of effective permittivity is a function of the reaction time. In this paper, we improve the method to obtain the effective permittivity as a function of the reactants?? concentrations and temperature by numerical fitting. Thus, the formula can be directly used for multiphysics calculation. Three measured effective permittivity curves for the iodination of acetone reaction under constant temperature were used to calculate the corresponding coefficients of the method at both 915?C2,450?MHz. The results calculated by the coefficients are in satisfactory agreement and approach the measured results.     

Heat capacity and stability of monoclinic selenium

Heat capacities of monoclinic selenium have been measured by computer interfaced differential scanning calorimetry from 100 to 379 K. Using literature data for low temperature heat capacities, enthalpies, entropies, and free enthalpies are calculated up to the zero entropy production melting temperature of 413 K. A comparison with trigonal selenium shows that there is no floor temperature for the stability of trigonal selenium. Monoclinic selenium is metastable relative to trigonal selenium at all temperatures.