新天花粉蛋白的盐酸胍去折叠过程

本文利用荧光光谱和园二色光谱研究了新天花粉蛋白的盐酸胍去折叠过程.结果显示:新天花粉蛋白的盐酸胍去折叠是一个只包含天然蛋白和变性终态的二态过程,与已经报道的天花粉蛋白的盐酸胍去折叠过程不同.     

π-π interactions in the self-assembly of melamine and barbituric acid derivatives

Self-assembly of a pair of complementary molecular components, 5-(4-dodecyloxyben-zylidene)-(1H,3H)-2, 4,6-pyrimidinetrione (PB₁₂)and 4-amino-2,6-didodecylamino-1, 3, 5-triazine (M₁₂) was studied by cyclic voltammogram, surface photovoltage spectroscopy, fluorescence spectroscopy, FTIR and X-ray diffraction. It is found that after mixing equimolar amount of PB₁₂ and M₁₂ at room temperature, not only triply complementary hydrogen bonds are formed between PB₁₂and M₁₂ but also further self-assembly of the supermolecules based on network of hydrogen bonds occurs via π-π interactions. During the self-assembly of the supermolecules, π -π interactions are induced by delocalized interactions between the HOMO of M₁₂ and the LUMO of PB₁₂, resulting in the formation of a supramolecular nanotube with a layered structure bearing a d value of 0.41 nm and PB₁₂ and M₁₂are arranged alternatively between adjacent supermolecules.     

给受体型化合物电氧化还原的电子结构

用MNDO方法研究了氰基乙烯基苯胺衍生物的电氧化还原行为, 以及给受体的前线轨道作用. 它们的共同氧化峰是给体氨基氮原子失去一个电子, 共同的还原峰是受体乙烯基反键轨道得到一个电子. 甲基的空间效应使DCEDMA形成准可逆的单电子过程. 稳定的叔自由基使TCEA~(-·)得到一个电子但又可失去.     

Preparation of sustained-release chlorpyrifos particles via the emulsification coacervation method and their sustained-release performance

MMA-HEMA-MAA ternary random copolymer (PA) and CaCl₂ was used as carrier and precipitant, respectively, and emulsification coacervation was adopted to prepare sustained-release chlorpyrifos particles. The particle size, morphology, structure, and the sustained-released performance of the samples were characterized. Results showed that porous and random sustained-release chlorpyrifos particles piled up into small spherical particles. Hydrogen-bonding interactions between PA and chlorpyrifos molecules were observed, and chlorpyrifos was dispersed among the PA molecules as both crystal and noncrystal forms. Raising chlorpyrifos concentrations resulted in larger proportions of chlorpyrifos distributed in the crystalline state. Chlorpyrifos was loaded into the PA crosslinked network structure and the heat resistance of the pesticide was improved significantly. The sustained-release process of chlorpyrifos was controlled by Fick diffusion mechanism, and the release mechansim of the drug consisted with the Korsmeyer-Peppas kinetic equation.     

π-π interactions in the self-assembly of melamine and barbituric acid derivatives

Self-assembly of a pair of complementary molecular components, 5-(4-dodecyloxyben-zylidene)-(1H,3H)-2,4,6-pyrimidinetrione (PB12) and 4-amino-2,6-didodecylamino-1, 3, 5-triazine (M12) was studied by cyclic voltammogram, surface photovoltage spectroscopy, fluorescence spectroscopy, FTIR and X-ray diffraction. It is found that after mixing equimolar amount of PB12 and M12 at room temperature, not only triply complementary hydrogen bonds are formed between PB12 and M12 but also further self-assembly of the supermolecules based on network of hydrogen bonds occurs via π-π interactions. During the self-assembly of the supermolecules, π-π interactions are induced by delocalized interactions between the HOMO of M12 and the LUMO of PB12, resulting in the formation of a supramolecular nanotube with a layered structure bearing a d value of 0.41 nm and PB12 and M12are arranged alternatively between adjacent supermolecules.     

~1H-NMR studies on cis-trans isomers of spheroidenes

All-trans spheroidene was extracted from the cells of Rhodobacer sphaeroides 2.4.1 and a set of cis-trans isomers were isolated from an isomeric mixture obtained by iodine-sensitized photo-isomerization of the all-trans isomer by high-pressure liquid chromatography (HPLC). On the basis of assignment of the 1H-NMR spectra (COSY, long-range COSY, rekyed COSY, ROESY and NOESY) of the all-trans isomer, the configurations of cis isomers were determined by the isomerization shifts of the olefinic 1H signals. The peaks of HPLC could be assigned as follows: A: 9,13'-cis, B1: 5,13-cis, B2: 13,9'-cis, C: 13-cis, E: 9-cis, F: 13'-cis, G: 5,9'-cis, H: 9'-cis, I: all-trans.     

Spectral properties of Nd-doped BiB_3O_6 crystal

Transparent Nd : BiB3O6 crystal has been grown by top-seeded method. The refraction indices of the crystal were measured and the parameters of chromatic dispersion were fitted. The room temperature absorption spectra of the crystal have been measured and compared with that of 0.2 mol/L NdCI3 solution. According to Judd-Ofelt (JO) theory, the spectral strength parameters Ω2 = 0.1776×10-20 cm2, Ω4 = 0.1282×10-20 cm2 and Ω6 = 0.1357×10-20 cm2 of Nd3+ ion were fitted. The radiative transition probabilities AJ,(?), oscillator strengths fJ,(?), radiative lifetime T and the branching ratio β(?) have all been calculated. Based on these parameters, the properties and application perspective are discussed.     

Mo_4(μ_3-O)_2O_4Cl_2(O_2CC_6H_5)_6和Mo_4(μ_3-O)_2O_4Cl_2(O_2CC_6H_4CH_3)_6·2C_6H_5Cl簇合物中弱M—M键的研究

测定了Mo_4(μ_(3-)O)_2O_4Cl_2(O_2CC_6H_5)_6和Mo_4(μ_(3-)O)_2O_4Cl_2(O_2CC_6H_4CH_3)_6·2C_6H_5Cl四钼簇合物在N,N-二甲基甲酰胺溶液中的循环伏安特性、电子吸收光谱、固体粉末样品的表面光电压谱和光声光谱。讨论Mo_2(V)结构单元中弱M—M键的特性,认定了Mo—Mo键前线区域轨道的对称标号。     

Aggregation behavior of amphiphilic D-p -A molecules bearing recognition group

Aggregation behavior of two amphiphilic D-π-A molecules bearing barbituric acid as both recogniton group and electron-drawing substituent , 5-(4-dodecyl oxybenzylidene)-(1H, 3H)- 2,4,6-pyrimidine trione (PB12) and 5-(4-N,N-didodecyl aminobenzylidene)-(1H,3H)-2,4,6-pyrimidine trione (AB12) was studied by UV-visible, fluorescence, and surface voltaic spectroscopies (SPS). The experimental results indicate that PB12 tends to form J-aggregate and AB12 tends to form H-aggregate under increasing concentration. An intramolecular twisted charge transfer (TICT) emission around 500 nm is observed when J-aggregate is formed between PB12 molecules, and an excimer emission around 600 nm is observed when H-aggregate is formed between AB12 molecules.     

SnO2超微粒薄膜上醇的催化氧化

等离子体化学气相沉积(PCVD)法可制备多孔柱状结构的SnO_2超微粒非晶薄膜,本文研究了薄膜在真空吸附体系中的膜电阻和IR谱随温度变化特性及乙二醇、正丙醇、异丙醇、乙醇和甲醇的气敏灵敏度,提出SnO_2薄膜上吸附氧O_2~-、O~-对醇的氧化机理 1实验与结果 自制PCVD装置抽空后充入40 Pa的O_2,加高频出现辉光,再充入CnCl_4使辉光转为蓝