PbO~2纳米粉体的固相合成及其对MnO~2电极材料的改性作用

利用固相氧化反应制备了PbO~2纳米粉体样品，借助XRD，TEM以及循环伏安测试对其性质进行了表征。同时，对反应条件的选择进行了讨论。将所得样品用于改性MnO~2电极，恒流放电测试结果表明，样品掺杂量在1.25%～5.00%间对MnO~2有良好的改性效果，可使改性MnO~2的放电容量得到极大提高。循环伏安测试结果表明，铅的掺入改变了MnO~2的放电机理。在循环扫描过程中，掺杂物与MnO~2均不再以单纯氧化物的形式存在，而是形成了一系列Pb(X)(X=0,Ⅱ)Mn(Y)(Y=Ⅳ，Ⅲ，Ⅱ)复合物的共氧化与共还原，抑制了电化学惰性物质Mn~3O~4的生成和积累，从而有望改善MnO~2的可充性能。纳米PbO~2与常粒径PbO~2与常粒径PbO~2(标记为S)对MnO~2的改性机理类似。但前者对MnO~2的改性效果明显优于后者，当恒流放电至-1.0V时，其放电容量较S样改性MnO~2的放电容量平均高出约30%。     

Asymmetric Diels-Alder Reactions of Chiral Menthyl α-Sulfinylacrylates

Introducing two chiral auxiliaries, sulfoxide and menthol, into an acrylate would have either matched or mismatched pair systems. The presence of chiral menthol in α-sulfinylacrylates can change the diastereoselectivity from 24% d.e. to a single diastereomer by manipulation of the double asymmetric strategy.     

Preparation and characterization of polyvinyl alcohol-capped CdSe nanoparticles at room temperature

Polyvinyl alcohol (PVA)-capped CdSe nanoparticles were successfully prepared by a one-step solution growth technique at room temperature and ambient pressure. X-ray diffraction, transmission electron microscopy, infrared spectra, and X-ray photoelectron spectra were used to characterize the final product. The as-prepared CdSe nanocrystals were well dispersed and uniform in shape and the diameter of the particles was confined within 8 nm. Ultraviolet-visible absorption spectra were used to study the confined growth process of PVA-capped CdSe nanoparticles. Photoluminescence measurement showed the near band-edge luminescence of the final product.     

CoTiO3纳米粉体的合成及其对MnO2电极材料的改性作用

采用溶胶-凝胶法制得钙钛矿型CoTiO₃纳米粉体，借助XRD、TEM以及循环伏安测试对其性质进行了表征。不同量的所制样品用于MnO₂电极的物理掺杂，进行了深度恒流放电、循环伏安和充放电测试。结果表明在40%KOH电解质溶液中，样品掺杂量为5%时改性效果较好。纳米CoTiO₃参与了电极反应，抑制了电化学惰性物质Mn₃O₄的生成，从而有效地改善MnO₂的放电性能，放电容量较I.C     

桥链七甲川菁的合成及光性能

菁是一种具有多功能用途的染料,除用作卤化银感光材料及有机光导材料的光谱增感剂、光记录材料中记录介质外,还可作为染料激光器中用的激光染料.我们曾合成了四甲川苯乙烯菁、五甲川(艹粦)及五甲川吡喃鎓等红外染料作为激光染料,测定了它们的光性能.本文合成了具有桥链的七甲川菁,研究了这些桥链七甲川菁的吸收光谱及荧光光谱,并以YAG激光倍频(532nm)作泵浦源,测定了它们的激光调谐范围、中心波长及激光转换效率.     

Expected and unexpected results from combined beta-hairpin design elements

A model beta-hairpin dodecapeptide [EFGWVpGKWTIK] was designed by including a favorable D-ProGly Type II' beta-turn sequence and a Trp-zip interaction, while also incorporating a beta-strand unfavorable glycine residue in the N-terminal strand. This peptide is highly folded and monomeric in aqueous solution as determined by combined analysis with circular dichroism and 1H NMR spectroscopy. A peptide representing the folded conformation of the model beta-hairpin [cyclic(EFGWVpGKWTIKpG)] and a linear peptide representing the unfolded conformation [EFGWVPGKWTIK] yield unexpected relative deviations between the CD and 1H NMR spectroscopic results that are attributed to variations in the packing interactions of the aromatic side chains. Mutational analysis of the model beta-hairpin indicates that the Trp-zip interaction favors folding and stability relative to an alternate hydrophobic cluster between Trp and Tyr residues [EFGYVpGKWTIK]. The significance of select diagonal interactions in the model beta-hairpin was tested by rearranging the cross-strand hydrophobic interactions to provide a folded peptide [EWFGIpGKTYWK] displaying evidence of an unusual backbone conformation at the hydrophobic cluster. This unusual conformation does not appear to be a result of the glycine residue in the beta-strand, as replacement with a serine results in a peptide [EWFSIpGKTYWK] with a similar and seemingly characteristic CD spectrum. However, an alternate arrangement of hydrophobic residues with a Trp-zip interaction in a similar position to the parent beta-hairpin [EGFWVpGKWITK] results in a folded beta-hairpin conformation. The differences between side chain packing of these peptides precludes meaningful thermodynamic analysis and illustrates the caution necessary when interpreting beta-hairpin folding thermodynamics that are driven, at least in part, by aromatic cross strand interactions.     

二氧化碳同环氧丙烷交替共聚用催化剂的研究

探讨了有机金属催化剂的组成及其对二氧化碳同环氧丙烷交替共聚产物结构的影响,发现二乙基锌—助剂体系的催化活性按如次顺序递降:二乙基锌—连苯三酚>二乙基锌—间苯二酚>二乙基锌—对苯二胺>二乙基锌—亚乙基脲。若用三异丁基铝代替二乙基锌同连苯三酚构成催化剂,则失去对二氧化碳同环氧丙烷交替共聚反应的活性同时,著者发现二乙基锌—二元芳胺催化体系与二乙基锌—二元酚催化体系的催化活性规律完全不同。     

壳聚糖／聚丙烯酸聚电解质复合物膜对水／有机液体系的渗透汽化性能

以壳聚糖和聚丙烯酸为原料制备了聚电解质复合物膜，并对其分离水／乙醇体系的渗透汽化特性和浓度，温度，化学组成等因素的影响进行了研究，发现后处理方法对复合物膜的分离性能影响很大。同时对其它水／有机液体系，该膜也具备优异的分离性能。     

纳米晶La_（1－_x）Sr_xFeO_3的合成及气敏特性的研究

用柠檬酸盐法合成出Ｌａ_（１－_ｘ）Ｓｒ_ｘＦｅＯ_３（ｘ＝０．１，０．２，０．３，０．４）原粉，再经固相反应得到纳米晶粉末，用ＴＧ、ＤＴＡ、ＸＲＤ、ＩＲ进行了表征，确证复合氧化物Ｌａ_（１－_ｘ）Ｓｒ_ｘＦｅＯ_３为钙钛矿型结构，粒径在１０～２５ｎｍ之间。实验结果表明，随着固相反应条件不同，产物粒径呈规律性变化．气敏特性研究表明，该纳米晶材料对乙醇有较高的选择性和灵敏度，其选择性顺序为Ｌａ_（０．９）Ｓｒ_（０．１）ＦｅＯ_３＞ＬａＦｅＯ_３＞ＬａＦｅＯ_３（大晶粒）。     

CVD Reactions of TiCl4 with Ammonia： a Quantum Chemical Study

Based on density functional calculations, the mechanism and the energetic course of the chemical vapor deposition （CVD） reaction of TiCl4 with NH3 were studied at the level of B3LYP with 6-311g（d） basis set. Furthermore, the polymerization processes of dimerization, trimerization and tetramerization were investigated. The calculation results indicate that the formation of polymers is favored at the elimination reaction. On the basis of the calculated energetics, a possible mechanism of the reduction reaction has been proposed.