Theoretical limiting concentration for mineralization of trichloromethane and dichloromethane in aqueous solutions by AOPs

It is widely stated that most organic contaminants could be completely mineralized by Advanced Oxidation Processes(AOPs). This statement means that the concentration of the organic contaminant at equilibrium(limiting concentration,LC)is low enough to be neglected.However,for environmental safety,especially drinking water safety,this statement needs to be verified from chemical engineering thermodynamic analysis.In this paper,trichloromethane(CHCl3)and dichloromethane(CH2Cl2) are selected as the model system...     

DNA-associated click chemistry

This review highlights the most recent advances in click chemistry associated with DNA.Cu[I]-catalyzed azides-alkynes Huisgen cycloadditions(CuAAC)and a strain-promoted alkyne-azide cycloaddition(SPAAC)are two popular click reactions that have great impact in DNA science.The simplicity,versatility,orthogonality,and high efficiency of click reaction along with a stable triazole product have been instrumental for the successful application of this reaction in the field of nucleic acid chemistry.CuAAC and SPAAC reactions have been widely used for DNA modification,including DNA labeling,metallization,conjugation,cross-linking,and ligation.Modified oligodeoxynucleotides obtained from click reaction have been extensively applied in the fields of drug discovery,nanotechnology,bio-conjugation,and material sciences,among others.The most recent advances in the synthesis and applications of clickable DNAs are discussed in detail in this article.     

新颖桥联核苷化合物的合成

报道了以鸟苷和尿苷为起始原料通过碱基端基连接而成两种新型桥联双聚体核苷的合成方法.通过1,2,4-三氮唑与POCl₃在缚酸剂Et₃N催化下分别与鸟苷碱基6-位和尿苷碱基4-位内酰胺羰基反应生成相应的1,2,4-三氮唑基核苷2和6,然后分别使其C-6和C-4位活化,进一步与二烷基胺反应,最后脱保护, 就很方便得到两种新型桥联双聚体核苷4和8.     

Application of L-thiazolidine-4-carboxylic acid monolayer in electrochemical determination of copper(Ⅱ)

L-Thiazolidine-4-carboxylic acid monolayer was prepared on gold electrodes through the self-assembly approach.Such novel thioether-based monolayer could efficiently preconcentrate Cu2+,which provided a simple,stable and reproducible method for the determination of Cu2+.The modified electrodes were stable enough to be continuously used for one week(more than 30 times regeneration) with lower than 10% decrease in the response.They retained their initial activity for more than one month if used once a day.The ...     

Unexpected proton spin‐lattice relaxation in the solutions of polyolefin and tetrachloroethane

‘Unexpected’ proton spin‐lattice relaxation (T₁) times are reported for the solutions of poly(ethylene‐co‐1‐octene) and tetrachloroethane‐d₂. For the residual protons of the deuterated solvent and the methyl and vinyl protons at the polymer chain ends, their T₁ relaxation times vary significantly with both the polymer concentration and molecular weight over a wide range. The T₁s also decrease with increasing temperature at relative high temperatures. Such behaviors are in contrast to most reported polymer solutions in which the T₁ has nearly no concentration or molecular weight dependence in the dilute and semi‐dilute regime, and normal dependence on temperature. Further investigation revealed that the paramagnetic oxygen effect did shorten the measured proton T₁s, but cannot account for the unexpected T₁ dependences. Spin rotation is proposed to provide a reasonable explanation. Copyright © 2010 John Wiley & Sons, Ltd.     

Pore structure analysis of PFSA/SiO_2 composite catalysts from nitrogen adsorption isotherms

The perfluorosulfonic acid (PFSA)/SiO2 composite catalysts were prepared by sol-gel method.Differences concerning pore structure analysis of PFSA/SiO2 catalysts were discussed on the basis of nitrogen adsorption.Their surface area and pore size distributions were evaluated by Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) methods,respectively.The nitrogen adsorption-desorption isotherms associated with adsorption hysteresis of PFSA/SiO2 catalysts were analyzed in detail.The adsorption isother...     

Effects of Pressure on Doped Kondo Insulators

The effects of pressure on the doped Kondo insulators (KI) are studied in theframework of the slave-boson mean-field theory under the coherent potential approximation.A unified picture for both the electron-type KI and hole-type KI is presented. The density ofstates of the f -electrons under the applied pressures and its variation with the concentrationof the Kondo holes are calculated selficonsistently. The specific heat coefficient, the zerotemperaturemagnetic susceptibility as well as the low-temperature electric resistivity of thedoped KI under various pressures are obtained. The two contrasting pressure-dependent effectsobserved in the doped KI systems can be.naturdy explained within a microscopic model.     

Morse指数与含Grushin算子的Liouville型定理

本文研究退化椭圆型方程-Δxu-(α+1)2|x|~(2α)Δyu=|u|~(p-1)u,(x,y)∈Rm×Rk和方程-Δxu-(α+1)2|x|~(2α)Δyu=|u|~(p-1)u,(x,y)∈Π的Liouville型定理,其中-Δx-(α+1)2|x|~(2α)Δy是Grushin算子,Π={(x,y)∈Rm×Rk:x10}或{(x,y)∈Rm×Rk:y10}.本文将证明,当1p(Q+2)/(Q-2)时,上述方程Morse指数有限的有界解只有零解,其中Q=m+(α+1)k为齐次空间的维数,因此,本文将Laplace方程的结果推广到含Grushin算子的方程.     

三元杂质砷锑钴对锌电沉积阴极过程的影响

采用电化学研究方法探讨了在锌电积过程中砷、锑、钴杂质对阴极极化过程的单一和共同影响,得出了单一杂质和三元杂质对锌电积过程影响的动力学方程及参数,并对其极化机理进行了研究.结果表明,含一元杂质的ZnSO4/H2SO4溶液的动力学参数与理论值基本一致,而含三元的ZnSO4/H2SO4溶液的传递系数α要比理论值小,说明杂质的存在及其含量的大小、品种的多少对锌电积影响程度不同.