Monte Carlo simulation of full energy spectrum of electrons emitted from silicon in Auger electron spectroscopy

A Monte Carlo simulation including surface excitation, Auger electron‐ and secondary electron production has been performed to calculate the energy spectrum of electrons emitted from silicon in Auger electron spectroscopy (AES), covering the full energy range from the elastic peak down to the true‐secondary‐electron peak. The work aims to provide a more comprehensive understanding of the experimental AES spectrum by integrating the up‐to‐date knowledge of electron scattering and electronic excitation near the solid surface region. The Monte Carlo simulation model of beam–sample interaction includes the atomic ionization and relaxation for Auger electron production with Casnati's ionization cross section, surface plasmon excitation and bulk plasmon excitation as well as other bulk electronic excitation for inelastic scattering of electrons (including primary electrons, Auger electrons and secondary electrons) through a dielectric functional approach, cascade secondary electron production in electron inelastic scattering events, and electron elastic scattering with use of Mott's cross section. The simulated energy spectrum for Si sample describes very well the experimental AES EN(E) spectrum measured with a cylindrical mirror analyzer for primary energies ranging from 500 eV to 3000 eV. Surface excitation is found to affect strongly the loss peak shape and the intensities of the elastic peak and Auger peak, and weakly the low energy backscattering background, but it has less effect to high energy backscattering background and the Auger electron peak shape. Copyright © 2014 John Wiley & Sons, Ltd.     

Organic dye bearing asymmetric double donor-π-acceptor chains for dye-sensitized solar cells

A novel efficient metal free sensitizer containing asymmetric double donor-π-acceptor chains (DC) was synthesized for dye-sensitized solar cells (DSSCs). Comparing to 3.80%, 4.40% and 4.64% for the DSSCs based on the dyes with single chain (SC1, SC2) and cosensitizers (SC1 + SC2), the overall conversion efficiency reaches 6.06% for DC-sensitized solar cells as a result of its longer electron lifetime and higher incident monochromatic photon-to-current conversion efficiency.     

低浓度样品拉曼光谱的实验研究

在液芯光纤内产生共振拉曼效应,可以提高拉曼光谱强度１０＾９倍。测定了１０＾－１０－１０＾－５ｍｏｌ／Ｌ浓度样品的拉曼光谱。实验结果表明,β－胡罗卜素在ＣＳ２中１５２０ｃｍ＾－１拉曼线的强度（散射系数）、频移、线宽随浓度降低而发生变化。     

Polyhydroxylated Sterols from the South China Sea Gorgonian Verrucella umbraculum

Two new polyhydroxylated sterols, named verumbsteroids A and B ( 1 and 2 , resp.), along with seven known analog, 3 – 9 , were isolated from the gorgonian Verrucella umbraculum collected from the South China Sea. The structures and relative configurations of the new compounds were elucidated by comprehensive spectroscopic investigations. The absolute configuration of 1 was determined by using modified Mosher method with the acetonide derivative of 1 . Compounds 1 and 3 – 5 were found to show cytotoxicities against five human tumor cell lines (HL‐60, K562, HeLa, A‐549, and HCT‐116) with the IC₅₀ values ranging from 2.76 to 9.62 μM .     

A {Nb6P2W12}‐Based Hexameric Manganese Cluster with Single‐Molecule Magnet Properties

By deliberately using a metastable polyanion [(NbO₂)₆P₂W₁₂O₅₆]^12? ( 1 ), which was formed in situ, we have discovered the unprecedented hexameric cluster {Mn₁₅(Nb₆P₂W₁₂O₆₂)₆} ( 2 ), in which the six polyanions [Nb₆P₂W₁₂O₆₁]^10? are alternately connected by four intriguing trinuclear {Mn^III₃} moieties and four {Mn^II} linkers. This discovery is the first in which the phosphoniobotungstate has been made accessible by using transition‐metal ions; furthermore, polyanion 2 represents the largest niobotungstate cluster reported to date. Analysis by means of electrospray ionization mass spectrometry (ESI‐MS ) provides insight into the self‐assembly process, and the peaks observed relate to the different charge states of the parent cluster, thus confirming the stability of 2 . In addition, magnetic‐susceptibility measurements reveal that each {Mn^III₃} subunit is a separate single‐molecule magnet (SMM). This discovery results from the exploration of the reverse effect of metastable polyanion 1 possessing high reactivity, thereby turning a disadvantage into an advantage. This finding could define a new synthetic strategy for the design and synthesis of magnetic polyoxometalate (POM) clusters.     

Interaction of multi-walled carbon nanotubes and zinc ions enhances cytotoxicity of zinc ions

More and more nanomaterials enter the environment along with their production, application and deposal. They may alter the biological effect of pollutants already existing in the real environment by different interactions. Therefore efforts should also be paid to investigate the combined toxicity of nanomaterials and pollutants. Herein, we studied the combined toxicity of oxidized multi-walled carbon nanotubes (O-MWCNTs) and zinc ions on cells. It is found that cytotoxicity of the combined O-MWCNTs and zinc ions elevates significantly, compared with O-MWCNTs or zinc ions alone. This result comes from the assays of cell morphology, cell viability and proliferation, cell membrane integrity, mitochondrial membrane potential and cell apoptosis. Mechanism studies indicate that O-MWCNTs absorb zinc ions and form slight aggregation. These enhance remarkably the cellular uptake of O-MWCNTs, and thus induce the death of cells by bringing in more zinc ions into cells. Our study indicates that the existence of nanomaterials could change the bioconsequence of other pollutants and emphasizes the importance of the combined toxicity research in the presence of nanomaterials.     

具有有源闭合腔的光纤光栅传感系统地址查询技术

基于熔融拉锥技术研制的3 dB宽带耦合器的光纤环形镜的工作原理,提出了一种新型的具有有源闭合腔装置的光纤光栅传感系统。在用作闭合共振腔端镜的环形镜中写入十个波分复用光纤光栅传感元,利用共振腔中接入的法布里-珀罗滤波器,通过控制电压对传感光栅的波长扫描,实现对传感地址的查询。用非平衡的迈克耳孙扫描干涉仪将传感光栅的波长漂移信息变为相移信息,实现传感信号的解调。系统传感灵敏度的实验值为1.5835°/10-6ε,与理论值(1.6662°/10-6ε)基本吻合。     

Determination of phthalate esters in liquor samples by vortex‐assisted surfactant‐enhanced‐emulsification liquid–liquid microextraction followed by GC–MS

A novel method using vortex‐assisted surfactant‐enhanced‐emulsification liquid–liquid microextraction has been developed for the extraction of phthalate esters (PAEs) in Chinese liquor samples prior to analysis by GC–MS. In the proposed method, a high‐density extraction solvent (carbon tetrachloride) was dispersed into samples with the aid of a surfactant (Triton X‐100) and vortex agitation, resulting in a short extraction equilibrium (30 s). After centrifugation, a single microdrop of solvent was easily collected for GC–MS analysis. Key factors that affected the extraction efficiency were optimized. Under the optimum conditions, linearity was found in the range from 0.05 to 50 μg/L. Coefficients of determination varied from 0.9938 to 0.9971. LODs, based on an S/N of 3, ranged from 4.9 to 13 ng/L. Enrichment factors varied from 140 to 184. Reproducibility and recoveries were assessed by testing a series of three liquor samples that were spiked with different concentration levels. Finally, the proposed method was successfully applied to the determination of PAEs in 16 Chinese liquor samples. In this work, high‐density‐solvent vortex‐assisted surfactant‐enhanced‐emulsification liquid–liquid microextraction was applied for the first time for the extraction of PAEs in Chinese liquor samples and was proved to be simple, rapid, and sensitive.     

丙烯酰胺共聚合及产物分散性的研究

采用水溶性引发体系研究了丙烯酰胺的均聚以及与几种乙烯基单体的共聚反应。探讨了引发剂、温度、单体浓度及加热时间对所得聚合物相对分子质量及其分散性能的影响。对产物的结构特性和相对分子质量分布进行了表征,并考察了共聚物的分散性能。丙烯酰胺共聚物同均聚物相比,分散性能有明显的改善。     

Theoretical study on conformational conversion of 1,3-dioxane inside a capsular host

The conformational conversion of 1,3-dioxane guest encapsulated inside a cylindrical capsular host was investigated with PM3 method and single point energies were evaluated by B3LYP method. When entrapped in the capsule, the guest tumbles were slower than that in the free condition. The influences of the inner phase of the capsule on the guest conformational conversion were discussed in detail.