固相浸渍法和湿浸渍法制备CuO/CeO2催化剂及其CO氧化性能的对比研究

采用固相浸渍法和常规湿浸渍法制备了一系列CuO/CeO₂催化剂,并结合X射线衍射（XRD）、氢气-程序升温还原（H₂-TPR）、激光拉曼光谱（LRS）、原位漫反射红外光谱（in situ DRIFTS）、X射线光电子能谱（XPS）等手段考察了制备方法对催化剂结构性质及其在CO氧化反应中性能的影响. XPS和H₂-TPR结果表明,固相浸渍法更有利于得到高分散的铜物种,并促进CuO物种的还原. LRS结果表明,相比于湿浸渍法,固相浸渍法能产生更多氧空位,而这些氧空位可以活化参与反应的O₂. CO氧化活性测试结果表明,当铜负载量相同时,固相浸渍法制备的催化剂相比于湿浸渍法表现出更好的催化性能. 结合多种表征结果发现,催化剂CO氧化性能与其表面氧空位和Cu⁺-CO浓度紧密相关,提出了CuO/CeO₂催化剂在CO氧化反应中可能的协同作用机制.     

LC Determination of Trace Biogenic Amines in Foods Samples with Fluorescence Detection and MS Identification

A pre-column derivatization method for the simple, sensitive determination of biogenic amines using 10-ethyl-acridine-3-sulfonyl chloride (EASC) as labeling reagent with fluorescence detection and mass spectrometry (MS) identification has been developed. After pre-column derivatization, the labeled biogenic amines were separated on a Hypersil BDS-C18 column by gradient elution. The derivatives showed an intense protonated molecular ion corresponding m/z [M + H]⁺ in positive-ion mode. The collision-induced dissociation of protonated molecular ion formed specific fragment ions at m/z 196.5, m/z 222.7, m/z 224.4 and m/z 272.5, m/z 286.2. Satisfactory linear responses were observed at the concentration range of 0.02?C10 ??mol L^?1 with coefficients of >0.9993. Detection limits obtained by the analysis of a derivatized standard containing 0.2 pmol of each biogenic amine, were from 20.22 to 109.2 fmol (at a signal-to-noise ratio of 3). The relative standard deviations of retention times and peak areas for each biogenic amine were <0.96 and 3.22%, respectively. Recoveries except for PUT were in the range of 96.7?C103.6% for chicken sausage and 95.8?C104.6% for pork sausage The established method for the determination of biogenic amines except for PUT from real samples was satisfactory.     

Preparation,structure and photocatalysis of metal-organic frameworks derived from aromatic carboxylate and imidazole-based ligands

Three 3-D metal-organic frameworks (MOFs), [Cd(NDC)(biim-4)]·0.5H₂O (1), [Cd₂(TDC)₂(biim-4)₂(H₂O)₂] (2) and [Zn₂(biim-4)₂(TDC)₂]·2.5H₂O (3) (biim-4 = 1,4-bis(1-imidazolyl) butyric alkyl; H₂NDC = 1,4-naphthalene dicarboxylic acid; H₂TDC = thiophene-2,5-dicarboxylic acid), have been synthesized under hydrothermal conditions and structurally characterized by single X-ray diffraction. The three MOFs have high photocatalytic degradation effects on methyl orange under UV irradiation. Through electronic structure analysis combined with time-dependent density functional theory calculations, catalytic performances of these materials are correlated with the molecular composition and the optoelectronic properties of the samples.     

氧化还原对Lindqvist型多金属氧簇复合物自组装的动态调控

Dynamic regulation of self-assembly is of vital importance in chemistry, biology and material science thanks to its great potential for development of smart materials and devices. Polyoxometalates (POMs) are a class of functional inorganic nanoclusters, which has become one of the excellent building blocks for supramolecular self-assemblies, especially when covalently or non-covalently modified by organic species. As typical stimuli-responsive functional clusters, the POMs could be photochemically or electrochemically reduced to mixed-valence states, of which the structural integrity remains even after encountering stepwise multi-electron redox process. The intriguing photochromism of the POMs in different states exhibits distinct photophysical properties, which motivates us to exploit the dynamic self-assemblies of POM-based complexes. The divalent Lindqvist-type hexamolybdate cluster [Mo₆O₁₉]^2- is one of the least negative-charged POMs, which is the ideal building blocks to construct novel assembly structures. Based on this motivation, herein, a single chain surfactant-encapsulated polyoxometalate (POM) complex (ODTA)₂[Mo₆O₁₉] was prepared by simple counterion replacement of Lindqvist-type (TBA)₂[Mo₆O₁₉] with octadecyltrimethylammonium (ODTA) in acetonitrile solution. The structure of the POM complex was confirmed by ¹H nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and elemental analysis. The solution of complex (ODTA)₂[Mo₆O₁₉] in the mixed solvents of acetonitrile and isopropanol with the volume ration of 4 to 1 exhibited reversible photochromism upon alternate UV light irradiation and air exposure. Upon UV light irradiation, the light yellow transparent solution of (ODTA)₂[Mo₆O₁₉] turned into blue quickly. The new broad absorption band appearing at ca.751 nm assigned to the Mo^V → Mo^VI intervalence charge-transfer (IVCT) transition, indicated the formation of reduced POM, as revealed by UV-Vis absorption spectra. After exposed to air, the blue solution was bleached. The alternate photochromism could be conducted for multiple cycles. Helical self-assembled morphology of (ODTA)₂[Mo₆O₁₉] was formed in acetonitrile/isopropanol, characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) methods. More interestingly, morphology transformation of the complex from helical strips to spherical assemblies occurred accompanied by photochromism occurrence. The morphology evolution during the photochromism process experienced from shortened helical strips through sea urchin-like aggregates to spherical assemblies. Most significantly, the helical assemblies could be recovered again after air oxidation, implying the reversible morphology transformation driven by redox stimulus. The redox-modulated reversible self-assembly is driven by the variation of electrostatic attraction between organic cations and inorganic anions as well as the electrostatic repulsion between inorganic ionic clusters, proved by X-ray photoelectron spectroscopy (XPS) and ¹H NMR spectra. The results will contribute to better understanding the mechanism of dynamic assemblies and inspire the precise fabrication of advanced smart materials.     

Profiling of Ubiquitination Modification Sites in Talin in Colorectal Carcinoma by Mass Spectrometry

Talin protein was partially purified from human colorectal carcinoma tissues, which was subject to tryptic digestion. Immunoaffinity precipitation with specific antibodies that recognize diglycyl-lysine(Lys) remnants from tryptic digestion of ubiquitinated peptides was used to enrich ubiquitinated sites in talin. Mass spectrometry coupled with capillary reverse-phase high-performance liquid chromatography was used to analyze tlie enriched peptides. Specifically, four peptides containing diglycyl-Lys remnants from talin, namely, TAK(ub)VLVEDTK, QQQYK(ub) FLPSELRDEH, K(ub)STVLQQQYNR, and EGILK(ub)TAK can be determined using mass spectrometric data. This study provides an analytical method for further study in tlie relationship between ubiquitination modification of talin and its biological activity in colorectal cancer tissues with different pathological processes.     

TiO2光催化剂在COD测定中的应用研究

采用溶胶一凝胶法制备纳米TiO2薄膜电极,提出了一种简便、快速测量化学需氧量(COD)的方法.分别以葡萄糖、邻苯二甲酸氢钾(KHP)为COD检测的标准物,考察了TiO2薄膜的光催化行为,并与传统方法进行比较.实验结果表明,葡萄糖对紫外光几乎没有吸收,在葡萄糖的电解质溶液中,COD与光电流有很好的一元二次关系;KHP对紫外光有吸收,在KHP的电解质溶液中,当COD浓度大于50mg/L时,随着COD浓度的增加,光电流降低.引入了单位光强度引起的电流响应(E)这一变量,该传感器的单位光强度引起的电流响应E与COD值在15.0-300mg/L范围内有很好的一元二次关系,相关系数为0.9999,并且不同样品在薄膜电极上的E呈现很好的线性关系.该传感器对水样的测量结果与传统方法测量结果相吻合.     

A Novel Labeling Reagent of 2-(12-Benzo[b]acridin-5-(12H)-yl)-acetohydrazide for Determination of Saturated and Unsaturated Fatty Acids in Traditional Chinese Herbs by HPLC-APCI-MS

A new fluorescence labeling reagent 2-(12-benzo[b]acridin-5(12H)-yl)-acetohydrazide (BAAH) has been designed for fatty acids labeling. Eleven fatty acids containing seven saturated and four unsaturated fatty acids were used to evaluate the analytical potential of this reagent. The labeling reaction of BAAH with fatty acids was completed at 85 °C for 60 min using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC·HCl) as the condensing agent. Separation of the derivatized fatty acids was carried out on a reversed-phase Thermo Hypersil Gold C18 column (4.6 mm × 250 mm, 5 μm) in combination with a gradient elution with a good baseline resolution. The fluorescence excitation and emission wavelengths were set at λ_ex 280 and λ_em 510 nm, respectively. The identification was carried out by the online APCI-MS in positive-ion detection mode. Linear correlation coefficients for all fatty acid derivatives were of >0.9994. Detection limits, at a signal-to-noise ratio of 3:1, were 3.89–12.5 nmol L⁻¹ for the labeled fatty acids. The developed method was successfully applied to the accurate determination of fatty acids in five traditional Chinese herbs with satisfactory results.

     

二乙基锌对原位产生吲哚亚胺的对映选择性加成反应

发展了乙基锌对原位产生的不饱和亚胺的对映选择性共轭加成,磺酰吲哚衍生物在乙基锌存在下原位生成不饱和亚胺,手性亚磷酰胺配体-铜络合物催化二乙基锌对该原位产生的不饱和亚胺反应以最高99%的产率和80%的对映选择性得到了一系列3位取代的光学活性的吲哚衍生物.     

高梯度绝缘子的实验研究与性能分析

为解决脉冲功率系统中绝缘部件的真空沿面闪络问题,开发了基于二次电子崩理论的层叠式高梯度绝缘材料。利用全金属超高真空分析系统,对高梯度绝缘子的真空出气特性进行检测;利用四极质谱仪,对高梯度绝缘子真空出气的气体成分进行分析。利用阻抗分析仪测试不同结构绝缘材料的高频介电性能。基于纳秒脉冲真空实验平台,对高梯度绝缘子的真空沿面闪络性能进行测试。研究结果表明:高梯度绝缘子具有良好的高频介电性能,其拐点频率高达200 MHz;锻炼后高梯度绝缘子的闪络场强可达190 kV/cm,其闪络性能和高梯度绝缘结构中绝缘层的材料及绝缘层与金属层的比例直接相关。