密度泛函理论研究边链对苯并菲电荷传输的影响

采用密度泛函理论在B3LYP/6-31G**水平上,根据电子转移的半经典模型对含有炔基的不同软链的苯并菲化合物分子的电荷传输性质进行研究。研究表明,所有目标化合物均有利于苯并菲的电荷传输。其中,直接在苯并菲刚性环上引入酰胺基（-CO-NH-）有利于提高正电荷的传输,而间隔基为酯基的单取代化合物的正负电荷传输性质均比较良好。在苯并菲上单取代的分子明显比其双取代、三取代的分子正电荷传输性质好。     

Differential and Integral Isoconversional Non‐linear Methods and Their Application to Energetic Materials. III. Non‐isothermal Decomposition Reaction Kinetics of Benzotrifuroxan

The thermal behaviour and decomposition reaction kinetics of benzotrifuroxan (BTF) were determined by TG and DSC techniques. The kinetic parameters of the exothermic decomposition reaction in a temperature programmed mode (the apparent activation energy Ea and pre-exponential factor A) were calculated by a single non-isothermal DSC curve. The E values calculated using the Kissinger and Flynn-Wall-Ozawa equations and integral isoconversional non-linear equations were used to check the validity of activation energy by a single non-isothermal DSC curve. The results show that the kinetic model function in integral form and the values of Ea and A of the decomposition reaction of BTFare , 109.95 kJ•mol－1 and 108.16 s－1, respectively. The values of ∆S≠, ∆H≠ and ∆G≠ of this reaction are －93.15 J•mol－1•K－1, 150.72 kJ•mol－1 and 153.15 kJ•mol－1, respectively. The critical temperature of thermal explosion of BTF is 257.33 ℃.     

Synthesis and Characterization of Copper(II) and Zinc(II) Tricyanomethanide (tcm) Complexes with Di(2‐pyridyl)amine (dpyam) as Co‐ligands: [Cu(dpyam)(tcm)2], [Cu(dpyam)(tcm)(OAc)] and Zn(dpyam)2(tcm)2

Three new transition metal tricyanomethanide complexes [Cu(dpyam)(tcm)₂] ( 1 ), [Cu(dpyam)(tcm)(OAc)] ( 2 ) and Zn(dpyam)₂(tcm)₂ ( 3 ) were synthesized and characterized by single crystal X‐ray diffraction analysis. In 1 each copper(II) atom is coordinated to three tcm anions and one dpyam molecule to form a square pyramide geometry. In 2 the coordination geometry around the central metal is also square pyramidal, and each copper atom is surrounded by two tcm anions, one dpyam ligand and one OAc. Both 1 and 2 display a µ_1,5‐tcm bridged infinite chain structure. In 3 each zinc(II) atom is coordinated by two tcm anions and two dpyam molecules to form a distorted octahedral geometry. Different from the former two complexes, 3 shows a mononuclear structure. Magnetic susceptibility measurement in the range 2–300 K indicates that there are weak antiferromagnetic couplings between adjacent copper(II) ions in 1 (J=?0.03 cm^?1) and 2 (J=?0.11 cm^?1) respectively.     

卵清蛋白与离子型表面活性剂的相互作用

本文通过荧光光谱法、紫外-可见吸收光谱法和透射电镜并结合电导率测定分别研究了水中卵清蛋白与阴离子表面活性剂十二烷基硫酸钠（SDS）和阳离子表面活性剂十二烷基三甲基溴化铵（DTAB）和十六烷基三甲基溴化铵（CTAB）之间的相互作用。研究结果表明卵清蛋白可以增加SDS和CTAB的临界胶束浓度,但对DTAB的临界胶束浓度没有影响。阴离子表面活性剂可以使卵清蛋白构象完全伸展,而阳离子表面活性剂却不具备此种作用。表面活性剂单体与卵清蛋白的相互作用强于表面活性剂胶束与卵清蛋白的相互作用。     

双硫腙加OP乳化剂直接比色法测定废水中的镉

利用聚氧乙烯烷基酚醚类（俗称OP乳化剂）的增色增溶作用,用双硫腙加OP乳化剂直接比色法测定废水中的镉。在0-5μg／mL范围内,镉浓度与吸光度线性相关,相关系数为0.999。方法的相对标准偏差为1.5％（n=5）,样品加标回收率为98.0％-101.9％。该法与国标GB7471-1987双硫腙分光光度法比较,操作简便、无毒性。     

High-performance thin-layer chromatographic analysis of selected organophosphorous pesticide residues in tea

The separation of 9 organophosphates (monocrotophos, quinalphos, triazophos, parathion-methyl, isofenphos-methyl, temephos, parathion, phoxim-ethyl, and chlorpyrifos) by high-performance thin-layer chromatography (HPTLC) with automated multiple development was studied. The HPTLC method was developed and validated for analysis of residues of phoxim-ethyl and chlorpyrifos in tea. The sample was extracted with acetonitrile and cleaned up by ENVI-CARB solid-phase extraction. The extract was directly applied as bands to glass-backed silica gel 60F254 HPTLC plates. The plates were developed with dichloromethane-hexane (1 + 1, v/v) in a glass twin-trough chamber. Evaluation of the developed HPTLC plates was performed densitometrically. The results indicated that the detection limits of phoxim and chlorpyrifos were 5.0 x 10(-9) and 1.0 x 10(-8) g, respectively. Recoveries of the pesticides from tea by this analytical method were 90.7-105.5%, and relative standard deviations were 7.3-13.5%. The precision and accuracy of the method were generally satisfactory for analysis of pesticide residues in tea.     

Impact of Lewis acids on Diels-Alder reaction reactivity: a conceptual density functional theory study

Density functional theory (DFT) and conceptual/chemical DFT studies are carried out in this work for the normal electron demand Diels-Alder reaction between isoprene and acrolein to compare chemical reactivity and regioselectivity of the reactants in the absence and presence of Lewis acid (LA) catalysts. A cyclic coplanar structure of acrolein-LA complex has been observed and the natural bond orbital analysis has been employed to interpret the interaction between acrolein and LAs. Reactivity indices from frontier molecular orbital energies are proved to be adequate and efficient to evaluate the catalytic property of LAs. Linear relationships have been discovered among the bond order, bond length, catalytic activation, and chemical reactivity for the systems concerned. The validity and applicability of maximum hardness principle, minimum polarizability principle, and minimum electrophilicity principle are examined and discussed in the prediction of the major regioselective isomer and the preferred reaction pathway for the reactions in the present study.     

广义Minkowski不等式的进一步改进

针对"亚正定阵理论(Ⅱ)"一文的广义Minkowski不等式不成立问题,在已有的修正结果基础上,给出一种完整的修正结果;并更正了"亚正定阵的几个开问题及一些不等式"一文中有关的错误结论;用反例说明"广义正定矩阵的进一步研究"一文中的有关结论是错误的,给出完整的修正结果.     

On generalized inverse transversals

Let S be a regular semigroup, S° an inverse subsemigroup of S.S° is called a generalized inverse transversal of S, if V（x）∩S°≠Ф. In this paper, some properties of this kind of semigroups are discussed. In particular, a construction theorem is obtained which contains some recent results in the literature as its special cases.