Chemiluminescence immunoassays

Over the last 25 years, radioimmunoassays have developed into highly sophisticated analytical systems capable of offering exquisite sensitivity and specificity. The expansion of the scope of their application from human health care to other areas such as food and water analysis is in part due to the move away from the use of radioactive tracers. Chemiluminescent molecules perhaps provide the most logical non-radioactive alternative.     

A second isoelectronic multiexciton center in annealed Czochralski silicon

A recently reported group of photoluminescence lines observed in thermally annealed Czochralski silicon is studied using photoluminescence, excitation, and transient spectroscopies. The properties of these lines are remarkably similar to those of another, higher energy, series reported earlier. As for this previous case, we conclude that the new lines result from bound exciton and bound multiexciton complex recombination on an inhomogeneously broadened distribution of isoelectronic binding centers.     

The structures of intergrowth tungsten bronzes of Ba,Sn, Pb,and Sb

The structures of intergrowth tungsten bronzes (ITB) of compositions Ba_0.04WO₃, Sn_0.04WO₃, Pb_0.04WO₃, Sn_0.18WO₃, and Sb_0.25WO₃ have been deduced from high-resolution electron microscope images. Both the Pb_0.04, Sn_0.04, and Ba_0.04, ITB phases consist of single rows of hexagonal tunnels occupied by Pb, Sn, or Ba atoms intergrown in a WO₃-like matrix. The Sb_0.25, ITB phase is composed of similar rows of Sb-containing single hexagonal tunnels, the centers of which are separated by a WO₃-like matrix only two octahedra in thickness. The structure of the Sn_0.18, ITB phase consists of double rows of hexagonal tunnels containing Sn atoms joined by a single strip of WO₃-like octahedra. The structures are compared with the structures of other known ITB phases and the nonstoichiometric behavior of these phases is discussed.     

水溶性糖基铱配合物的合成、表征及成像分析

设计、合成了3种水溶性糖基金属铱配合物[（dfppy）₂Ir（bpy-sugar）]Cl（1）、[（tpy-COOH）₂Ir（bpy-sugar）]Cl（2）和[（mpbq）₂Ir（bpy-sugar）]Cl（3）（dfppy=2-（2,4-二氟苯基）吡啶,tpy-COOH=4-（2''-吡啶基）苯甲酸,mpbq=2-甲基-3-苯基苯并[g]喹喔啉,bpy-sugar=4,4''-二（1-硫代-β-D-葡萄糖甲基）-2,2''-联吡啶）,利用核磁共振波谱、高分辨质谱、红外光谱和元素分析对其进行结构表征,并研究其光物理性质及其在细胞成像中的应用。通过辅助配体的调控,可以实现配合物从黄色到近红外的不同波长发光。配合物1和2在水溶液中表现出黄色发光,发射波长分别为546和584 nm,配合物3在水和二甲基亚砜的混合溶液（39：1,V/V）中表现出近红外发光,发射波长为780 nm。配合物1和2具有相对较高的量子产率（16.9%和3.1%）和较长的发光寿命（0.22和0.10 μs）。在配体上修饰不同的基团可以增大配合物的细胞穿透性和水溶性,实现配合物在细胞内的成像分析。从细胞成像结果可以看出,金属铱配合物能够穿过细胞膜进入到细胞,且与4,6-联脒-2-苯基吲哚（DAPI）染色的细胞核部分有所重合,说明进入到了细胞核。同时配合物的发光情况良好,说明在细胞所在的生物环境中,这种配合物仍是稳定的。     

密度泛函理论研究α-MoC(100)在甲醇水蒸汽重整中的催化作用

本文通过密度泛函理论计算方法探究了α-MoC催化甲醇水蒸气重整(CH₃OH+H₂O→CO₂+3H₂)反应,系统地研究了甲醇水蒸气重整反应中相关中间体的吸附行为和基本步骤的动力学. 结果表明,在α-MoC(100)表面,甲醇容易裂解形成CH₃O中间体,CH₃O进一步脱氢为CH₂O. 通过比较CH₂O和OH缔合过程和CH₂O直接分解过程,发现CH₂O和OH之间更容易形成CH₂OOH而不是分解成CHO和H. 计算结果表明,CH₂OOH中间体的连续脱氢对CO₂有很高的选择性. 相反,在α-MoC(111)表面,由于CH₂O中间体的强吸附使其更偏向于脱氢生成CHO,最后生成产物CO. 此外,高水解离产生的OH物种可以促进中间体O-H键的断裂,并显著降低反应能垒. 本文不仅揭示了α-MoC(100)晶面在甲醇水蒸气重整反应中的催化作用,也为α-MoC基催化剂的设计提供了理论指导.     

Supercell calculation on the ideal silicon single vacancy

Supercell calculations on a Si diamond lattice with 16, 54 and 128 sites containing one ideal vacancy are performed using a semi-ab-initio method. The electronic density of defect states shows an approximate linear relationship to the size of the supercell. Extrapolation of the result indicates that for a supercell of about 222 sites, the defect interaction between the adjacent cells will be negligible and the T₂ defect state is estimated to be at about 0.85 eV above the valence band edge.     

Halogen-Driven Bandgap Opening in Graphdiyne for Overall Photocatalytic Water Splitting

In this work, we studied the electronic band structure of the halogen (F, Cl, and Br) functionalized graphdiynes (GDYs) by using hybrid density functional theory. The results revealed that the bandgap energies of modified GDYs increase as the number of halogen atoms increases. It is also found that the position of the valence band maximum (VBM) is influenced by the electronegativity of halogen atoms. The higher the electronegativity, the deeper the VBM of the GDYs modified by the same number of halogen atoms. Importantly, our results revealed that the bandgap of GDY could be effectively tuned by mixing types of halogen atoms. The new generated conduction band and valence band edges are properly aligned with the oxidation and reduction potentials of water. Further thermodynamic analysis confirms that some models with mixing types of halogen atoms exhibit higher performance of overall photocatalytic water splitting than non-mixing models. This work provides useful insights for designing efficient photocatalysts that can be used for overall water splitting.     

Recent advances in 1D nanostructured catalysts for photothermal and photocatalytic reduction of CO2

The development of photocatalysts that can efficiently convert CO₂ into other valuable chemicals via photocatalytic and photothermal processes is critical to the current energy and climate change problems. However, low separation of charge carriers, short light absorption, and low activation of CO₂ molecules in photocatalysis limit the catalysts’ performance. Designing 1D heterostructures containing multiple materials can be a viable solution as their unique properties, such as high surface area, short diffusion paths of charge carriers, and enhanced light absorption properties, can potentially promote the reaction rate and product selectivity. In this review, we summarize the general features of heterostructures involving nanotubes, nanowires, nanorods, and nanobelts. Next, the main synthesis strategies are briefly highlighted, followed by the most important findings concerning their catalytic activity in the photothermal and photocatalytic CO₂ reduction processes. The article concludes with some of the current challenges and potential solutions.     

Synthesis of 3-perfluoroalkyl-substituted 1,2,4-triazinones through copper(I)-catalyzed interrupted click reaction

A Cu-catalyzed interrupted click reaction for the synthesis of 3-perfluoroalkyl-substituted 1,2,4-triazinones is developed. The reaction between the terminal alkynes with azides and pentafluoropropionic or heptafluorobutyric anhydride proceeds smoothly to afford the corresponding pentafluoroethylated or heptafluoropropyled products in good yields. This protocol is applicable to various types of substrates including arylacetylenes and aliphatic azides having electron-rich and electron-deficient groups. The broad substrate scope and functional group tolerance of the reaction makes this approach a practical method for the synthesis of valuable 3-perfluoroalkyl-substituted 1,2,4-triazinones. Some of the title compounds showed fungicidal activity against cucumber downy mildew (CDM).