Nanosheet‐Enhanced Asymmetric Induction of Chiral α‐Amino Acids in Catalytic Aldol Reaction

An efficient ligand design strategy towards boosting asymmetric induction was proposed, which simply employed inorganic nanosheets to modify α‐amino acids and has been demonstrated to be effective in vanadium‐catalyzed epoxidation of allylic alcohols. Here, the strategy was first extended to zinc‐catalyzed asymmetric aldol reaction, a versatile bottom‐up route to make complex functional compounds. Zinc, the second‐most abundant transition metal in humans, is an environment‐friendly catalytic center. The strategy was then further proved valid for organocatalyzed metal‐free asymmetric catalysis, that is, α‐amino acid catalyzed asymmetric aldol reaction. Visible improvement of enantioselectivity was experimentally achieved irrespective of whether the nanosheet‐attached α‐amino acids were applied as chiral ligands together with catalytic Zn^II centers or as chiral catalysts alone. The layered double hydroxide nanosheet was clearly found by theoretical calculations to boost ee through both steric and H‐bonding effects; this resembles the role of a huge and rigid substituent.     

荧光猝灭法测定痕量六价铬

基于六价铬与碘化钾反应生产了单质碘，碘可以使2′，7′－二氯荧光素（DCF）发生荧光猝来，从而间接测定六价铬。六价铬浓度在0．20－2．50μg/25ml范围内，荧光强度差值与六价铬浓度呈线性关系，线性回归方程△F=12．12 0．19，相关系数r=0.9993，检出限为0．10μg/ml。方法简便，灵敏度较高，已用于合成样中六价铬的测定。回收率在100％－103％，结果满意。     

Dye-sensitized solar cells based on a single-crystalline TiO2 nanorod film

Highly crystalline TiO2 nanorods with lengths of 100-300 nm and diameters of 20-30 nm have been synthesized by a hydrothermal process in a cetyltrimethylammonium bromide surfactant solution. The microstructure measured by X-ray diffraction and high-resolution transmission electron microscopy was a pure highly crystalline anatase phase with a long nanorod shape. The addition of a triblock copolymer poly(ethylene oxide)100-poly(propylene oxide) 65-poly(ethylene oxide)100 (F127) decreased the length of the nanorods and kept the rod shape of the particles even after sintering at high temperatures. The rod shape kept under high calcination temperatures contributed to the achievement of the high conversion efficiency of light-to-electricity as discussed in the paper. A high conversion efficiency of light-to-electricity of 7.29% was obtained with the TiO2 single-crystalline anatase nanorod cell.     

关于二维Euler方程解的存在唯一性的一个附注

在局部存在唯一性的基础上,本文证明了当ω０ ∈Ｌ（２,１） 及ｕ０ ∈Ｃｒ 时二维Ｅｕｌｅｒ方程解的整体存在唯一性．这里Ｌ（２,１） 是Ｌｏｒｅｎｔｚ空间, Ｃｒ 是Ｈ氹ｌｄｅｒ空间     

芳香PET树脂母粒的研制

通过丙烯酸和丙烯酸正丁酯溶液共聚合，得到丙烯酸－丙烯酸正丁酯共聚物，该树脂与环氧氯丙烷反应后再与PET树脂切片继续反应，可使PET树脂切片表面形成聚丙烯酸酯自膨润型吸油网络结构，将表面具有聚丙烯酸酯自身膨润型吸油网络结构的PET树脂切片（简称为留香剂）在油溶性香精中浸泡，香精就被吸附在留香剂表面，即得到芳香PET树脂母粒。用SEM观察了母粒的表面结构形态。     

A New Triterpenoid from "Gualou-xiebai-baijiu-tang" Consisting of Fructus trichosanthis and Bulbus allii mtacrostemi

A new triterpenoid saponin was isolated by bioactivity-guided isolation from "Gualou-xiebai-baijiu-tang" consisting ofFructus trichosanthisi and Bulbus allii macrostemi. Its structure was determined as 3-O-β-D-galactopyranosyl-hederagenin 28-O-β-D-xylopyranosyl (1→6)- β-D-galactopyranosyl ester by means of chemical evidences and spectral analysis.     

Preparation and optical properties of Eu(III) complexes J-aggregate formed on the surface of silver nanoparticles

Ag colloidal nanoparticles coated with Eu(TTA)₃ · 2H₂O complexes were prepared, and it was found that Eu(TTA)₃ · 2H₂O complexes J-aggregate was formed on the surface of Ag nanoparticles according to a red shift (18.2 nm) in UV–Vis spectra. However, there had similar excitation wavelength, which was attributed to existence of Ag nanoparticles. Highly luminescent properties of Ag colloidal nanoparticles were observed, and it was believed to result from low energy transfer between Eu(III) complexes and Ag and the large electromagnetic field arising from the excitation of surface plasmon polariton of Ag nanoparticles.     

Novel carboxylated oligothiophenes as sensitizers in photoelectric conversion systems

Novel carboxylated oligothiophenes with different thiophene units were designed and synthesized as photosensitizers in dye-sensitized solar cells (DSSCs) for efficient opto-electric materials. The introduction of -COOH into thiophene molecules can lead to a red shift of UV-visible absorption, increase light-harvesting efficiency, and enhance photoinduced charge transport by forming efficient covalent bonds to the substrate surface. A red shift of the absorption spectrum of oligothiophene is also achieved by the increase in the number of thiophene units. The DSSCs based on the oligomers have excellent photovoltaic performances. Under 100 mW cm(-2) irradiation a short-circuit current of 10.57 mA cm(-2) and an overall energy conversion efficiency of 3.36 % is achieved when pentathiophene dicarboxylated acid was used as a sensitizer. The incident photo-to-current conversion efficiency (IPCE) has a maximum as high as 80 %. In addition, photovoltage and photocurrent transients show that slow charge recombination in DSSCs is important for efficient charge separation and excellent photoelectric conversion properties of the oligomers. These initial and promising results suggest that carboxylated oligothiophenes are efficient photosensitizers.     

相变温度低且宽的含有胆甾烯基和反式-4-烷基环己基苯氧基的二介晶化合物

Unsymmetrical dimesogenic compounds with cholesteryl and 4-（trans-4-n-alkylcyclohexyl）phenoxy parts were synthesized by condensation of cholester-3-yl 6-bromohexanoate with appropriate 4-（trans-4-n-alkylcyclohexyl）- phenols. Structures and thermal phase behaviour of these dimesogenic compounds have been confirmed by IR, IH NMR, elemental analysis, DSC, polarity microscopy and XRD measurements. Their thermal phase behaviour was significantly different with that of other cholesterol-based dimesogens while they exhibited low and wide phase transition temperature.