β-氨基酸的合成: 等当体方法的应用

β-氨基酸是一类在药物开发和生物研究中有广泛应用的中间体. 由等当体合成β-氨基酸的方法具有结构定制、合成产物丰富、直观等特点, 是β-氨基酸合成领域中不可或缺的合成方法. 重点介绍近年来该领域具有代表性的工作.     

Molecular dynamics of CO in few-cycle laser fields

We experimentally study the ionization, fragmentation and Coulomb explosion of CO using 6 fs laser pulses. Different from previous observations in tens or hundreds of femtoseconds laser pulses, strong charge asymmetric dissociation and CO²⁺ are observed in the current intense few-cycle laser field.     

A novel threefold‐interpenetrating primitive cubic network based on a dinuclear Zn2 node

In the mixed‐ligand metal–organic polymeric compound poly[[μ₂‐1,4‐bis(imidazol‐1‐yl)benzene](μ₂‐terephthalato)dizinc(II)], [Zn₂(C₈H₄O₄)₂(C₁₂H₁₀N₄)]_n or [Zn₂(bdc)₂(bib)]_n [H₂bdc is terephthalic acid and bib is 1,4‐bis(imidazol‐1‐yl)benzene], the asymmetric unit contains one Zn^II ion, with two half bdc anions and one half bib molecule lying around inversion centers. The Zn^II ion is in a slightly distorted tetrahedral environment, coordinated by three carboxylate O atoms from three different bdc anions and by one bib N atom. The crystal structure is constructed from the secondary building unit (SBU) [Zn₂(CO₂)₂N₂O₂], in which the two metal centers are held together by two bdc linkers with bis(syn,syn‐bridging bidentate) bonding modes. The SBU is connected by bdc bridges to form a two‐dimensional grid‐like (4,4)‐layer, which is further pillared by the bib ligand. Topologically, the dinuclear SBU can be considered to be a six‐connected node, and the extended structure exhibits an elongated primitive approximately cubic framework. The three‐dimensional framework possesses a large cavity with dimensions of approximately 10 × 13 × 17 Å in cross‐section. The potential porosity is filled with mutual interpenetration of two identical equivalent frameworks, generating a novel threefold interpenetrating network with an α‐polonium topology [Abrahams, Hoskins, Robson & Slizys (2002). CrystEngComm, 4 , 478–482].     

Photoinduced Polymerization for Entrapping of Octadecylsilane Microsphere for Capillary Liquid Chromatography

A short length of a sol‐gel monolith was initially prepared as the temporary frit in a 100 μm inner diameter fused‐silica capillary by an in situ photopolymerization. The packed 4 μm octadecylsilane particles were then immobilized within the identical sol‐gel solution through the same photopolymerization process. The prepared fritless capillary column was examined for the chromatographic performance by the self‐developed capillary liquid chromatography system. Baseline separation of the model analytes was achieved including thiourea, benzene, toluene and ethylbenzene with the lowest theoretical plate height about 66 μm for the retained component. A scanning electron micrograph was used to characterize the temporary frit and entrapped microspheres. The inorganic polymer matrix in the microsphere‐packed column functioned to link microspheres at specific sphere‐sphere and sphere‐capillary contact points. Furthermore, the stability and porosity of the fritless column were systematically investigated by a simple flow method.     

以卟啉为中心核的树枝状化合物

以卟啉基为中心核的树枝状化合物具有特殊的物理、化学及光电性能,其中一个重要特性是具有优良的能量和电子转移性能,近年来研究人员合成了一系列新型的以卟啉为中心核的树枝状化学物,这些化合物在许多领域有着潜在的应用前景。本文综述了近几年来以卟啉基为中心核的树枝状化合物的最新研究结果,介绍了一些具有代表性的新型化合物,概述了部分化合物的合成方法及性能,这些化合物由于其结构改变带来的性能变化,分别在光收集材料、发光材料、光动力学疗法、催化剂、传感器等领域有着潜在的应用前景。最后展望了此类化合物的发展方向。     

A new piezoelectric response model for population growth of bacteria

A piezoelectric response model on the population growth of microorganism is proposed. This model is based on a novel population growth model, which has a more obvious ecological meaning and the fact that the series piezoelectric quartz crystal (SPQC) sensor responses to conductivity changes of the medium during the growth of the microorganism. From the response model four parameters can be obtained including the maximum specific growth rate mu(m), saturated population size N(m), and two constants C and K(1). The influence of the parameters on the response curve is discussed in which the influences of mu(m) and N(m) are more obvious. With the proposed model the quantitative determination of bacteria may be more accurate than the frequency detection time (FDT) method. Then the growth of Escherichia coliform (E. coli) monitored with a SPQC sensor is compared with the simulated growth curve obtained by the proposed model and a good agreement is obtained.     

硅酸钠与有机硅氧烷前驱体自组装杂化硅基中孔材料

采用有机硅氧烷(RTES)与硅酸钠(Na2SiO3)共水解缩聚合成有机官能化的MSU型硅基中孔材料.考察了合成体系pH值对材料织构性能的影响以及不同有机硅氧烷与硅酸钠在中性条件下的自组装行为.发现在中性条件下，加入NaF可以有效避免带有较小有机基团的有机硅氧烷进入材料孔壁的可能性，而且合成体系的pH值对材料的孔径有一定的调控作用.     

稀土吸附剂城市污水深度除磷

采用以分子筛为载体、负载镧制成复合吸附剂对城市污水进行深度除磷.实验结果表明:研制的稀土吸附剂适于处理弱酸性废水.对于城市污水含磷浓度为1.0 mg·L-1,当pH值3～7,吸附剂的投加量在0.06 g·L-1,吸附3 h时,磷的去除率可达99.5%,出水pH值在6.0～8.5之间.     

毛细管气相色谱法测定塑料食品包装袋中苯、乙酸乙酯的残留量

选用HP-FFAP型毛细管柱(30m×0.25mm i.d.,0.25 μm)和氢火焰离子化检测器,建立了测定塑料食品包装袋中苯、乙酸乙酯残留量的气相色谱分析方法。测定苯、乙酸乙酯的线性范围分别为0.120～4.000、0.170～4.000μg/mL,相关系数分别为0.9998、0.9995,检出限分别为0.048、0.068μg/mL,加标回收率分别为96.4％、100.8％,测定结果的相对标准偏差分别为3.1％、1.0％。     

恒电流库仑滴定中电气因素的影响

分析恒电流库仑滴定过程中电气因素的影响,包括恒流源输出精度的影响、参考标准不确定度的影响、外部连接线路的影响、实验环境对电路的影响等,提出了减小这些影响的办法。