氨碱法制取碳酸钠实验方法的改进探讨

针对氨碱法制备碳酸钠实验中,氨气大量逸出造成的产率降低及由此带来的实验环境污染等问题,通过分次加入氨水、采用酚酞作为指示剂调控氨水用量,对氨碱法制备碳酸钠实验进行了改进,不仅提高了反应产率,缩短了反应时间,更有效地改善了实验室环境,有利于保护师生的身心健康。     

同步辐射真空紫外光电离质谱研究乙烯扩散火焰

本文利用探针取样法结合同步辐射真空紫外光电离和分子束质谱技术研究了常压下的乙烯扩散火焰.通过测量光电离质谱和光电离效率谱分辨了该火焰中大部分的燃烧中间体及产物;通过改变探针取样位置以及半定量计算得到了其中部分燃烧中间体及产物的摩尔分数曲线.实验结果为探索多环芳烃和烟尘在扩散火焰中形成的最初阶段的反应机理提供了依据.     

Two-dimensional turbulent flow chromatography coupled on-line to liquid chromatography–mass spectrometry for solution-based ligand screening against multiple proteins

We present herein a novel bioseparation/chemical analysis strategy for protein–ligand screening and affinity ranking in compound mixtures, designed to increase screening rates and improve sensitivity and ruggedness in performance. The strategy is carried out by combining on-line two-dimensional turbulent flow chromatography (2D-TFC) with liquid chromatography–mass spectrometry (LC–MS), and accomplished through the following steps: (1) a reversed-phase TFC stage to separate the protein/ligand complex from the unbound free molecules, (2) an on-line dissociation process to release the bound ligands from the complexes, and (3) a second mixed-mode cation-exchange/reversed-phase TFC stage to trap the bound ligands and to remove the proteins and salts, followed by LC–MS analysis for identification and determination of the binding affinities. The technique can implement an ultra-fast isolation of protein/ligand complex with the retention time of a complex peak in about 5 s, and on-line prepare the “clean” sample to be directly compatible with the LC–MS analysis. The improvement in performance of this 2D-TFC/LC–MS approach over the conventional approach has been demonstrated by determining affinity-selected ligands of the target proteins acetylcholinesterase and butyrylcholinesterase from a small library with known binding affinities and a steroidal alkaloid library composed of structurally similar compounds. Our results show that 2D-TFC/LC–MS is a generic and efficient tool for high-throughput screening of ligands with low-to-high binding affinities, and structure-activity relationship evaluation.     

基于二吡唑配体的镉配合物:温度诱导自组装、荧光和光催化应用

通过改变溶剂热反应温度,合成了2个结构不同的镉配合物[Cd₂（H₂ppty）₂（SO₄）₂（H₂O）₂]·3H₂O（1）和[Cd₂（ppty）（SO₄）（H₂O）₂]_n（2）（H₂ppty=3,5-bis-（1H-pyrazol-3-yl）-[1,2,4]triazol-4-ylamine）。进一步的研究表明,1和2的结构分别包含有双核和四核镉簇单元,呈现出零维和二维的结构。并且在室温下对2个配合物的荧光性质也进行了测试。固体紫外漫反射表明1和2的光学带隙分别为1.87和2.32 eV,因此它们对亚甲基蓝的光降解反应表现出了良好的催化活性。     

Fingerprinting and simultaneous determination of alkaloids in Picrasma quassioides from different locations by high performance liquid chromatography with photodiode array detection

A simple and sensitive method was developed and validated for profiling and simultaneous quantitation of seven alkaloids (6-hydroxy-β-carboline-1-carboxylic acid, β-carboline-1-carboxylic acid, β-carboline-1-propanoic acid, 3-methylcanthin-5,6-dione, 5-hydroxy-4-methoxycanthin-6-one, 1-methoxycarbony-β-carboline, and 4,5-dimethoxycanthin-6-one) in Picrasma quassioide grown in different locations by high-performance liquid chromatography with photodiode array detection. The analysis was conducted on a Phenomenex Gemini C(18) column at 35°C with mobile phase of 25 mM aqueous ammonium acetate (pH 4.0, adjusted by glacial acetate acid) and acetonitrile. A common fingerprint chromatograph under 254 nm consisting of 27 peaks was constructed for the evaluation of the similarities among 31 P. quassioide samples. Samples from Guangdong and Guangxi Provinces were found to be within group linkage and showed significant difference from that of Jiangxi Province origin by using principal component analysis and hierarchical clustering analysis. In addition, the seven alkaloids were identified by electrospray ionization mass spectrometry and comparing with reference standards and literature data. All of them were determined simultaneously using the established HPLC method. This rapid and effective analytical method could be employed for quality assessment of P. quassioide, as well as pharmaceutical products containing this herbal material.     

Robot learning schemes that trade motion accuracy for command simplification

This study was inspired by the human motor control system in its ability to accommodate a wide variety of motions. By contrast, the biologically inspired robot learning controller usually encounters huge learning space problems in many practical applications. A hypothesis for the superiority of the human motor control system is that it may have simplified the motion command at the expense of motion accuracy. This tradeoff provides an insight into how fast and simple control can be achieved when a robot task does not demand high accuracy. Two motion command simplification schemes are proposed in this paper based on the equilibrium-point hypothesis for human motion control. Investigation into the tradeoff between motion accuracy and command simplification reported in this paper was conducted using robot manipulators to generate signatures. Signature generation involves fast handwriting, and handwriting is a human skill acquired via practice. Because humans learn how to sign their names after they learn how to write, in the second learning process, they somehow learn to trade motion accuracy for motion speed and command simplicity, since signatures are simplified forms of original handwriting. Experiments are reported that demonstrate the effectiveness of the proposed schemes.     

Palladium-Catalyzed Direct C2-and Further C7-Acylation of Indoles with Aldehydes

The palladium‐catalyzed direct C2‐ and further C7‐acylation of indoles with aldehydes have been developed. This method provides a convenient pathway toward a variety of mono‐ and diacylated indoles.     

Eosin-sensitized photoreduction of benzil with 1-benzyl-1,4-dihydronicotinamide

The mechanism of eosin-sensitized photoreduction of benzil with 1-benzyl-1,4-dihydronicotinamide — a model compound of NAD(P)H and the behavior of the excited states of eosin have been investigated. The effect of anthracene as a diffusion-controlled quencher of the photoreaction indicates that both excited triplet state and an unquenchable excited singlet state of eosin participated in the sensitized photoreaction. From the Stern-Volmer plot of quantum yield vs. anthracene concentration, the triplet reaction rate constant has been calculated to be 0.78 × 10⁸ L M^?1S^?1 while the singlet reaction rate constant determined from quenching of eosin fluorescence by benzil is equal to 7.2 × 10⁹ L M^?1S^?1. The singlet and triplet quantum yields are also determined to be 0.09 and 0.18 respectively. Since both the singlet and triplet energies of eosin are lower than that of benzil, energy transfer sensitization is not feasible. It is proposed that electron transfer from the excited eosin to benzil is responsible for the initiation.     

碳氟醇对全氟辛酸钠表面活性及胶团反离子结合度的影响

The surface and micelle property of C_7F_(15)COONa/C_3F_7CH_2OH aqueous solution are investigated by surface tension, conductance, electromotive force methods. The results show that when adding C_3F_7CH_2OH into C_7F_(15)COONa solution the surface activity of C_7F_(15)COONa and the counterion binding degree of micelle can be enhanced.     

The Numerical Simulation of the Climatic Change Caused by CO_2 Doubling

The IAP two-level atmospheric general circulation model was coupled to a 60-m-deep mixed layer ocean model and a zero-layer thermodynamic model to simulate the climatic effects induced by a doubling of CO_2 concentration in the atmosphere.The global surface temperature is 1.75℃ when CO_2 is doubled. This value is lower than most of other results in the world, such as those of GFDL, NCAR, UKMO, GISS and OSU models.There are large regional and seasonal differences in the climatic change. Great warming is found in the Northern Hemisphere's high-latitude region anti the Antarctica; and the warming in land areas is greater than in ocean areas, while the precipitation increases in high latitudes and tropical regions but decreases in subtropical regions. In both hemispheres, the warming is greater in winter than in other seasons. As for the changes in China, we find that the precipitation in southwestern and northern China greatly decreases in summer but increases in winter.