Metathesis of Butylene-2 and Ethylene to Propylene over 3.0Mo/(Hβ+ γ-Al203) Catalysts with Different γ-Al203 Contents

A series of 3. 0Mo/(Hβ γ-Al2O3) samples with γ-Al2O3 contents in the range of 0-100% (mass fraction) was studied by means of XRD, NH3-TPD, TPR and BET determinations for characterizing their structures. The Hβ zeolite structure in the 3. 0Mo/Hβ sample can be effectively stabilized by adding some γ-Al2O3to Hβ zeolite. γ-Al2O3 mainly favors the formation of polymolybdate or multilayered Mo oxide, while Hβmainly forms the Al2(MoO4)3 species, as evaluated by the TPR technique. When used as the catalyst for the metathesis of butylene-2 and ethylene to propylene, there exists a close correlation between the specific surface area and stability of the catalyst. The specific surface area of the catalyst shows the maximum when (Hβ γ-Al2O3) contains 30%γ-Al2O3, which is in agreement with that of the time needed for the reaction stablization. In the case of maximum surface area, the rate of coke deposition is the minimum.     

高温气化条件下Na_2O对煤灰中矿物质演化行为的影响

利用XRD和FT-IR考察了高温弱还原气氛下Na_2O对两种硅铝含量不同的煤灰中矿物质组成的影响,揭示了Na_2O影响煤灰熔融特性的本质。通过Fact Sage计算了高温下矿物质反应的ΔG,探讨了Na_2O影响煤灰中矿物质组成的机理。结果表明,Na_2O对煤灰矿物质组成的影响与原煤灰的硅铝含量密切相关。硅铝总含量82.89%的煤灰,Na_2O含量为5%-20%时,钠长石和霞石的生成是煤灰熔融温度降低的主要原因;当Na_2O含量大于20%时,导致煤灰熔融温度降低的原因是霞石的生成。硅铝总含量47.85%的煤灰,Na_2O含量小于10%时,没有含钠矿物质生成;当Na_2O含量大于10%时,主要生成菱硅钙钠石、青金石和含钠的硅铝酸盐矿物,导致煤灰熔融温度降低。Fact Sage计算表明生成含Na矿物质反应的ΔG较小,其在高温下更容易发生。     

共价有机骨架材料在样品前处理中的研究进展

共价有机骨架（COFs）是由有机单体通过共价键连接形成的二维或三维晶体多孔结构。作为一种新兴的晶体多孔材料,COFs已经在气体储存、催化、传感、药物输送等各个领域广泛应用。近年来,COFs材料由于密度低、表面积大、结构可控等优点,在分析化学方面显示出巨大的潜力。该文综述了多孔COFs及其复合材料在样品前处理中的研究应用,包括分散固相萃取、固相微萃取和磁性固相萃取等。     

基于混合式教学和形成性评价的仪器分析实验教学改革与实践

在仪器分析实验课程中进行了基于混合式教学和形成性评价的实验教学改革。结果表明：教改组学生的自主学习能力、学习兴趣和动手能力都得到了提高;教改组学生的课程成绩总体优于对照组,t检验（p<0.05）说明2个组的成绩具有显著性差异。可见混合式教学模式和形成性评价体系有利于拓展学习空间,激发学生学习兴趣,培养学生自主学习能力,全面、客观评价学习效果。     

Tradeoff between mixing and transport for electroosmotic flow in heterogeneous microchannels with nonuniform surface potentials

Electroosmotic flow (EOF) is a phenomenon associated with the movement of an aqueous solution induced by the application of an electric field in microchannels. The characteristics of EOF depend on the nature of the surface potential, i.e., whether it is uniform or nonuniform. In this paper, a lattice Boltzmann model (LBM) combined with the Poisson-Boltzmann equation is used to simulate flow field in a rectangular microchannel with nonuniform (step change) surface potentials. The simulation results indicate that local circulations can occur near a heterogeneous region with nonuniform surface potentials, in agreement with those by other authors. Largest circulations, which imply a highest mixing efficiency due to convection and short-range diffusion, were found when the average surface potential is zero, regardless of whether the distribution of the heterogeneous patches is symmetric or asymmetric. In this work, we have illustrated that there is a trade-off between the mixing and liquid transport in EOF microfluidics. One should not simply focus on mixing and neglect liquid transport, as performed in the literature. Excellent mixing could lead to a poor transport of electroosmotic flow in microchannels.     

A Novel Photoproduct of 1, 3-Dimethyluracil in Phosphate Buffered-saline

1, 3-Dimethyluracil （DMU） in phosphate buffered-saline （PBS, pH=8） was irradiated by a medium pressure mercury lamp （MPML） and produced a novel compound C6H9N2O6P. The composition and structure of the compound has been identified by elemental analysis, EIMS, UV, IR, ^1H and ^31P-NMR.     

Effect of ligand structure of stationary phase of high performance hydrophobic interaction chromatography on renaturation efficiency of GuHCl-denaturedα-chymotrypsin

The renaturation of the denaturedα-chymotrypsin (α-Chy) with 1.7 mol·L-1 gua-nidine hydrochloride (GuHCI) by three kinds of stationary phase of high performance hydropho-bic interaction chromatography (STHIC) with a comparable hydrophobicity but different ligand structures was investigated. The obtained result indicates that the ligand structures of the three STHIC contribute to the renaturation efficiency ofα-Chy in the order of the end ligands PEG-600< phenyl group < tetrahydrofurfuryl alcohol (THFA).     

在线阴离子富集-石墨炉原子吸收光谱法的研究

将流动注射在线预富集系统与石墨炉原子吸收光谱法联用,以强碱型阴离子交换纤维为柱填充材料,以浓盐酸为络合剂,以稀盐酸为洗脱液,用固定洗脱液体积方式测定了Cd,Pb和Zn,富集倍数分别为19,17和15(与直接引入40μL进样量相比),检出限(3σ,ng/L)分别为1.1,8.2和2.6.     

一些大取代二茂铁三碘化物的合成和结构分析

合成了一系列大取代二茂铁三碘化物,通式为(RC~5H~4)~2FeI~3。通过元素分析,红外光谱,质谱,顺磁共振谱,穆斯堡尔谱和电导率对这些化合物进行了表征。测定了化合物[CH~2(CH~2)~3C(2-CH~2C~5H~4N)C~5H~4]~2FeI~4.H~2O的晶体结构,该晶体属三斜晶系,P-1空间群,晶胞参数:a=0.9593(1),b=1.3999(2),c=1.4537(2)nm。α=109.64(1),β=97.25(1),γ=104.69(1)ⅲ。V=1.7299nm^3,Mr=1030.13,Dx=1.98g/cm^3,Z=2。结果表明,取代二茂铁被碘部分氧化,导致中心金属铁表现为混合价态;由于茂环上大取代基的影响,使得I~3^-与I~3^-之间未能形成碘链,因此这些化合物的电导率很低。     

环氧溴丙烷或环氧氯丙烷/溴代萘/β-环糊精三元包接络合物的燐光性质

在β-环糊精溶液中,环氧溴丙烷(EBH)或环氧氯烷(ECH)能够诱导α-溴代萘(α-BrN)和β-溴代萘(β-BrN)强的室温燐光(RTP).结果证明,EBH比ECH有更强的重原子增强效应(HAEE);α-BrN/ECH/β-CD三元包接合物的稳定性比β-BrN/ECH/β-CD稳定性更强.