非离子型表面活性剂组成的微乳液热力学性质 (IV) 烷烃的碳原子数影响

由表面活性剂、醇、油和水所组成的微乳液,油相的烷烃长度会影响到微乳液的性质,主要表现在界面相组成和界面张力.Birdi 用加溶法研究以十六烷、硬脂酸钠、水和醇(从C_5到C_9)所组成的微乳液,醇的碳原子数n_a 与标准自由能△G(?)有以下关系:△G(?),醇=1563-839.5n_a(J·mol~(-1)在同样体系内,戊醇和不同烷烃则:     

Direct observation of cations and polynucleotides explains polyion adsorption to like-charged surfaces

We show an experimental approach for directly observing the condensation of polynucleotides and their electrolyte counterions at a liquid/solid interface. X-ray standing waves (XSW) generated by Bragg diffraction from a d = 20 nm Si/Mo multilayer substrate are used to measure the distinct distribution profiles of the polyanions and simple cations along the surface normal direction with subnanometer resolution. The 1D spatial sensitivity of this approach is enhanced by observing the XSW induced fluorescence modulations over multiple orders of Bragg peaks. We study the interesting divalent cation driven adsorption of anionic polynucleotides to anionic surfaces by exposing a hydroxyl-terminated silica surface to an aqueous solution with ZnCl2 and mercurated poly-uridylic acid (a synthetic RNA molecule). The in situ long-period XSW measurements are used to follow the evolution of both the Zn and Hg distribution profiles during the adsorption process. The conditions and physical mechanisms that govern the observed divalent cation adsorption and subsequent polynucleotide adsorption to an anionic surface are explained by a thermodynamic model that incorporates nonlinear electrostatic effects.     

Porous nanocomposites of zirconium dioxide and silicate

Highly porous nanocomposites of zirconium dioxide and silicate are synthesised in an aqueous system from an inorganic salt of zirconium; the nanacomposites, with tailorable pore structures, exhibit superior performance as catalyst supports.     

Synthesis and characterization of chitosan-graft-polycaprolactone copolymers

The graft copolymers of chitosan with polycaprolactone (PCL) were prepared through a protection-graft-deprotection route using phthaloylchitosan as intermediate. PCL macromonomers terminated with isocyanate groups reacted with hydroxyl groups of phthaloyl-protected chitosan regioselectively, and then phthaloyl groups were deprotected to give the free amino groups. The graft reaction was carried out in homogeneous system and yielded copolymers with high grafting content due to solubilization. FTIR, NMR and XRD were detected to characterize the resultant chitosan-graft-PCL copolymers.     

PVC/PBD-b-PMMA共混体系相容性的研究

采用ＤＭＡ和ＴＥＭ系统研究了聚丁二烯－聚甲基丙烯酸甲酯的嵌段共聚物（ＰＢＤ－ｂ－ＰＭＭＡ）与聚氯乙烯（ＰＶＣ）共混体系的相容性问题。结果表明：ＰＶＣ／ＰＢＤ－ｂ－ＰＭＭＡ共混体系具有部分相溶性。相容的程度与共混体系的组成、组分聚合物的分子量以及共聚物中ＰＢＤ和ＰＭＭＡ嵌段的比例密切相关。     

Co-C bond dissociation energy and reaction volume change of 2',5'-dideoxyadenosylcobalamin studied by laser-induced time-resolved photoacoustic calorimetry

Time resolved photoacoustic calorimetry (PAC) was applied to a study of the photolysis of a coenzyme B(12) analog 2',5'-dideoxyadenosylcobalamin, which lacks an -OH group at the 2' position of ribofuranose ring. In aqueous solution, we report for the first time the quantum yield Phi(d) (0.25+/-0.02), Co-C bond dissociation energy (BDE; 31.8+/-2.5 kcal mol(-1)) and reaction volume change deltaV(R) (6.5+/-0.5 ml mol(-1)) due to conformation changes of the corrin ring and its side chains accompanying the cleavage of the Co-C bond. These values for the analog are very similar to those for the natural cofactor. Based our results and previous studies, a possible explanation for the similarity in their structure and properties versus the large difference in their enzymatic activity is discussed.     

固相萃取-气相色谱-高分辨质谱法测定巢湖水中半挥发性有机化合物

描述了巢湖水中半挥发性有机化合物的提取、测定过程和初步结果。湖水中半挥发性有机化合物的提取采用XAD-2和XAD-4混合树脂富集，用气相色谱-高分辨质谱法测定了所萃取的有机化合物，并给出相应的分子式和结构式。春季湖水中检测到14种有机化合物。     

TEOS-MTES基SiO2溶胶微结构的SAXS研究

正硅酸乙酯(TEOS)为前驱体,在碱性条件下制备含有无定形SiO2颗粒的溶胶,以甲基三乙氧基硅烷(MTES)在酸性条件下获得聚甲基硅氧链,二者混合后应用同步辐射X射线进行混合溶胶的SAXS散射强度测定,计算了溶胶的平均回转半径、平均粒径、两相界面层厚度、散射体体积分数、两相间比表面积等参数,辅以光子相关光谱法(PCS)和透射电子显微镜(TEM)观测溶胶粒度,证实SiO2颗粒被MTES混合物连接成族团.实验发现所测混合溶胶样品均表现出对Porod定理的负偏离,说明溶胶中颗粒与溶剂之间存在很明显的两相间界面层.     

Ab initio study of Rg2I− (Rg = Ar,Kr, Xe)

The equilibrium geometries, vibrational frequencies, and dissociation energies of rare gas iodine clusters Rg₂I^?(Rg = Ar, Kr, Xe) were calculated at the Hartree–Fock (HF), second‐order Møller–Plesset (MP2), the coupled cluster method with single and double excitation and a noniterative correction for triple excitations method [CCSD(T)] levels. The title species have bent C_2v structure of about 60° angle. The electron correlation effects and relativistic effects on the geometry and stability were investigated at CCSD(T) level. Both effects stabilize title species. The calculated electron affinities are in good agreement with the experimental results available. The effect of high angular momentum functions (g and h) was studied. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

新型除草剂及其杂质的LC-MS和GC-MS分析

High performance liquid chromatography (HPLC) and electrospray ionization mass spectrometry (ESI-MS) have been utilized to analyze the synthesized 2-(2-arylaminomethylphenoxy)pyrimidine derivatives, which are a new kind of environmentally benign herbicides and have passed the temporary pesticide registration. The identification of main product and impurities has been achieved according to the UV and mass spectra. Moreover, one impurity, introduced by the raw material in the last step of the synthetic route, was identified by GC-MS analysis. It can be concluded that the combination of chromatography and mass spectrometry, including LC-MS and GC-MS, provided a vital tool of the pesticide science.