Ceria supported Ru~0-Ru~(δ+) clusters as efficient catalyst for arenes hydrogenation

Selective hydrogenation of aromatic amines,especially chemicals such as aniline and bis(4-aminocyclohexyl)methane for non-yellowing polyurethane,is of particular interests due to the extensive applications.To conquer the existing difficulties,in selective hydrogenation,,the Ru~0-Ru~(δ+)/CeO_2 catalyst with solid frustrated Lewis pairs was developed for aromatic amines hydrogenation with excellent activity and selectivity under relative milder conditions.The morphology,electronic and chemical properties,especially the Ru~O-Ru~(δ+) clusters and reducible ceria were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),sca nning electronic microscopy(SEM),X-ray photoelectron sp ectroscopy(XPS),CO_2 tempe rature programmed deso rption(CO_2-TPD),H_2 tempe rature programmed reduction(H_2-TPR),H_2 diffuse reflectance Fourier transform infrared spectroscopy(H_2-DRIFT),Raman,etc.The 2% Ru/CeO_2 catalyst exhibited good conversion of 95% and selectivity greater than 99% toward cyclohexylamine.The volcano curve describing the activity and Ru state was found.Owning to the "acidic site isolation" by surrounding alkaline sites,condensation between the neighboring amine molecules could be effectively suppressed.The catalyst also showed good stability and applicability for other aromatic amines and heteroarenes containing different functional groups.     

钴（Ⅱ）与2,2’-联吡啶-1,1’-二氧化物的多核配合物的合成和性质

以无水CoCl2和2,2’-联吡啶-1,1’-二氧化物为原料,在DMF溶剂中合成了一种多核配合物.经元素分析、紫外光谱、红外光谱和摩尔电导等方法测得它的组成为[Co3(bipyO2)4Cl4]Cl2,并对该配合物的气敏特性进行了研究. 结果表明, 该配合物对氨气有良好的敏感性和选择性.由它制作的传感器可望用于涉氨化工生产中氨浓度的自动测量和控制.     

Quantitative study on selective stacking of zwitterions in large-volume sample matrix by moving reaction boundary in capillary electrophoresis

The paper advanced the theoretical procedures for quantitative design on selective stacking of zwitterions in full capillary sample matrix by a cathodic-direction moving reaction boundary (MRB) in capillary electrophoresis (CE) under control of electroosmotic flow (EOF). With the procedures, we conducted the theoretical computations on the selective stacking of two test analytes of L-histidine (His) and L-tryptophan (Trp) by the MRB created with 30 mM pH 3.0 formic acid-NaOH buffer and 2-80 mM sodium formate. The results revealed the following three predictions. At first, the MRB cannot stack His and Trp plugs if less than 12.5 mM sodium formate is used to form the MRB and prepare the sample matrix. Second, the MRB can stack His and/or Trp sample plugs completely if higher than 50 mM sodium formate is chosen to form the MRB. Third, the MRB can only focus His plug completely, but stack Trp plug partially if 20-50 mM sodium formate is used; this implied the complete MRB-induced selective stacking to His rather than Trp. All the three predictions were quantitatively proved by the experiments. With great dilution of sample matrix and control of EOF, controllable, simultaneous and MRB-induced selective stacking and separation of zwitterions were achieved. The theoretical results hold evident significances to the quantitative design of selective stacking conditions and the increase of detection sensitivity of zwitterions in CE. In addition, the control of EOF by cetyltrimethylammonium bromide (CTAB) can evidently improve the stacking efficiency to both His and Trp.     

毛细管电泳中高盐样品在线富集的研究进展

在毛细管电泳分析过程中，简便高效的高盐样品处理技术对血清、尿液、海水和工业废水等样品的富集分析具有重要的意义。综述了在CE中高盐样品在线富集的若干种方法，包括乙腈法、瞬间等速电泳法、pH修饰法、动态pH联接法、胶束反应法和瞬间移动化学反应界面法，并简要地介绍它们的应用和研究进展。     

Metrological role of neutron activation analysis. IB. Inherent characteristics of relative INAA as a primary ratio method of measurement

This is the second part of a paper which deals with the advantages and disadvantages of relative instrumental neutron activation analysis concerning traceability and uncertainty, and the current scope and possible future extensions of neutron activation analysis as a primary ratio method. The first part of this paper has been published in this Journal [1]. Received: 19 March 2001 Accepted: 2 October 2001     

聚酰亚胺/SiO2杂化膜的制备、表征和气体渗透性能

采用溶胶凝胶法,在以TiO2为过渡层的硅藻土-莫来石陶瓷膜管基底上,制备了组分不同的聚酰亚胺/SiO2杂化膜。聚酰亚胺是利用4,4′-六氟亚异丙基邻苯二甲酸酐、2,4,6-三甲基-1,3-苯二胺和3,5-二氨基苯甲酸在溶液中进行亚胺化完成的。采用FT-IR、TG/DTA、DSC、SEM、BET和气体渗透测定对膜进行了表征和测试。结果表明,聚酰亚胺通过支链上的羧酸基和SiO2相键连织构成了具有规则孔道的空间网状结构,并且随着SiO2含量的增加孔径逐渐减小;杂化膜具有较高的热稳定性和有机无机兼容性;相对于聚酰亚胺膜,杂化膜对H2、CO2和H2O与N2相比较具有较高的分离性,SiO2含量为25(wt)%的杂化膜对H2/N2、CO2/N2和H2O/N2的分离因子分别达到55.9、31.1和42.8。     

Diffusion characteristics of a T-type microchannel with different configurations and inlet angles.

A series of symmetrical and asymmetrical microfluidic T-sensors with different inlet angles were fabricated to study the mixing characteristics of a T-type microstructure for generating concentration gradient. Computational fluid dynamics (CFD) simulations showed that the concentration gradient, transition zone and diffusion length were different for various configurations and inlet angles. Quick mix and sharp concentration gradient occurred in the asymmetrical structure with large inlet angle. The observed concentration gradients in the fabricated microchannel were consistent with the theoretical prediction. In this microstructure, stagnant zone and z-direction diffusion also affected the concentration gradient. Based on the simulation results, the microfluidic structure was optimized to generate desired concentration gradient for a cell-based study.     

喷雾热解法合成球形(Y,Gd)BO3:Eu荧光粉的研究

采用喷雾热解法合成了无团聚的球形(Y,Gd)BO3∶Eu荧光粉。研究了各因素对(Y,Gd)BO3∶Eu荧光粉体的结晶性能、外观形貌及发光强度的影响。结果表明,按120%硼酸的化学计量比于900℃喷雾热解,再经过1200℃后处理2 h,可以合成结晶良好的(Y,Gd)BO3∶Eu荧光粉体;喷雾热解溶液的浓度和载气流量对荧光粉的外观形貌影响较大;铕含量为10%时可以获得最佳的发光强度。在优化喷雾热解实验条件下成功合成出良好发光强度的PDP用(Y0.6Gd0.3)BO3∶Eu0.1荧光粉。     

A novel three-component reaction for the synthesis of new 4-azafluorenone derivatives

Reaction of arylidenemalononitriles, 1,3-indanedione, and mercaptoacetic acid or 4-methylbenzenethiol is successfully carried out using microwave heating. It is an efficient and promising synthetic strategy to build the indenopyridine skeleton.     

LIGHT-SCATTERING STUDY OF POLYELECTROLYTE HOLLOW CAPSULES

Silver halide (AgX) microcrystal was used as template to synthesize hollow polyelectrolyte capsules. These hollow capsules were characterized by laser light scattering (LLS) used to measure the size of the capsules in solution. The ratio of hydrodynamic radius (Rh) from dynamic LLS to the radius of gyration (Rg) from static LLS is almost unity, revealing that the entities are hollow in solution. The results suggest that the LLS method can be regarded as a good complement to the confocal laser scanning microscopy (CLSM) method for the characterization of small hollow capsules, and it possesses the advantage of not needing fluorescence labeling.