Further Develop 1,3,4-Thiadiazole Based Probe to Effectively Detect 2,4,6-Trinitrophenol with the Help of DFT Calculations

Four fluorimetric probes had been developed to rapidly detect 2,4,6-trinitrophenol (TNP). They were designed and synthesized on the basis of 1,3,4-thiadiazole framework combining calculation with experiment. Among them, SK-1 displayed strong blue emission with fluorescence quantum yield as high as 63.6% in solution. Further evaluation demonstrated that SK-1 displays good selectivity and high sensitivity for rapid and visual detection of TNP. It brought significant changes in both colour and fluorescence emission spectrum. The detection limit was as low as 38 nM. Quenching mechanism was confirmed as photo-induced electron transfer (PET) by nuclear magnetic titration and DFT calculations. What’s more, application in real water samples and solid phase paper tests illustrated the practical significance of detection of TNP in both vapor and solution.

     

Native chemical ligation of thioamide-containing peptides: development and application to the synthesis of labeled α-synuclein for misfolding studies

Thioamide modifications of the peptide backbone are used to perturb secondary structure, to inhibit proteolysis, as photoswitches, and as spectroscopic labels. Thus far, their incorporation has been confined to single peptides synthesized on solid phase. We have generated thioamides in C-terminal thioesters or N-terminal Cys fragments and examined their compatibility with native chemical ligation conditions. Most sequence variants can be coupled in good yields with either TCEP or DTT as the reductant, though some byproducts are observed with prolonged TCEP incubations. Furthermore, we find that thioamides are compatible with thiazolidine protection of an N-terminal Cys, so that multiple ligations can be used to construct larger proteins. Since the acid-lability of the thioamide prohibits on-resin thioester synthesis using Boc chemistry, we devised a method for the synthesis of thioamide peptides with a masked C-terminal thioester that is revealed in situ. Finally, we have shown that thioamidous peptides can be coupled to expressed protein fragments to generate large proteins with backbone thioamide labels by synthesizing labeled versions of the amyloid protein α-synuclein for protein folding studies. In a proof-of-principle experiment, we demonstrated that quenching of fluorescence by thioamides can be used to track conformational changes during aggregation of labeled α-synuclein.     

用特征编码模板实现多模式分类识别的方法

以编码理论和神经网络优化算法为基础,提出了一种构造编码模板用于识别某一类模式集的方法,并以26个大写英文字母的识别作为实验进行了研究。     

Positively charged covalent organic framework and its application in the dispersive solid-phase extraction of ultraviolet-filters from food packaging material migrants

Abstract

Covalent organic frameworks (COFs) show excellent property, such as high porosity and excellent structure stability and were well applied in fields such as catalysis and adsorption, but most of the COFs showed similar structure and thus similar adsorption performance. Modification of simple COFs to enhance its adsorption performance in separation technique is an important issue. In this study, quaternary ammonium groups with long hydrophobic chain were introduced into a simple COF (TpPa-1) for the first time. The positively charged COF (PC-TpPa-1) can form electrostatic interaction and hydrophobic effect with negatively charged analytes, and showed good adsorption performance for ultraviolet-filters (UV filters). Under the optimum conditions, i.e. adsorbent amount 20?mg, pH?=?7, 1.0?mL acetonitrile as eluent, the obtained recoveries for all UV filters were in the range of 86.4–96.7%.The developed method was successfully applied to the determination of UV filters from food packaging material migrants with the aid of HPLC as a detector.     

Al70Co15Tb5Ni10合金中准晶相关相的高压研究

 使用静高压熔态淬火方法，在Al₇₀Co₁₅Tb₅Ni₁₀合金中截获到迄今为止晶胞参数最大的两个十次准晶的Penrose-Tiling相关相。其晶胞参数分别为：简单正交晶体a=6.11 nm，b=0.4 nm，c=8.4 nm；底心正交晶体a=6.11 nm，b=0.4 nm，c=8.4 nm。其晶体结构和晶胞参数与目前理论上的预言基本吻合。     

光学神经网络中硬件误差对性能影响的分析

利用统计方法，分析了光学硬件误差对用Ｈｏｐｆｉｅｌｄ神经作联想记忆时出错率的影响，导了系统的误差与错率关第的近似公式，并给出了模拟结果。得到了一定限度的误差对出错率的影响并不显著的的结论，特别坚探讨测器阵列动态范围的要求，可以远远小于其探测到的最大值。这对光学神经网络系统的设计及硬件的选取，具有指导意义。     

Effects of surface-active substances on acid–base indicator reactivity in SiO2 gels

Methyl orange (MO) and phenolphthalein (P) doped SiO₂ gels derived from tetraethyl orthosilicate (TEOS) and modified with cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and stearic acid (SA) are prepared. FTIR and TG analyses are used to characterize the gels. The color changes and leaching behavior of MO and P within the gels are investigated and explained on the basis of the gel structures and the reaction mechanism. The experimental results show that surface-active substances have obvious effects on the acid–base response and the leaching behavior of the acid–base indicators within the SiO₂ gels.     

氢原子束探针数据采集、存贮和处理系统

本文叙述氢原子束探针数据采集和处理系统,它由电压波形存贮器及APPLEⅡ微机组成。文中给出了典型实验数据和实验曲线。     

一种新的单极相似度判别法及其光电实现

提出一种新的单极神经元相度差别法，提高单极ＷＡＴ模型的存储容量，且能将与存储模式相差较大的输入模式差别出来，同时给出了光电实现系统及实验结果，单极模型的这一改进，使得单极系统具有全双极模型的特性，而且系统的空间和时间带宽积得到充分的利用。     

Radioactive contamination of the environment as a result of uranium production: a case study at the abandoned Lincang uranium mine,Yunnan Province,China

The distribution of radioactive pollutants, such as²²²Rn, U, Th and²²⁶Ra in the air, surface waters, soils and crops around the Lincang uranium mine, Yunnan Province, China, is studied. The mechanical, geochemical and biogeochemical processes responsible for the transport and fate of the radioactive elements are discussed based on the monitoring data. The pollutants concentrations of effluents from the mine tunnels were dependent on pH and which were controlled by biochemical oxidation of sulfide in the ore/host rocks. Radon anomalies in air reached 4 km from the tailings pile depending on radon release from the site, topography and climate.²³⁸U and²²⁶Ra abnormities in stream sediments and soil were 40—90 cm deep and 790—800 m away downstream. Anomalies of radioactive contaminants of surface watercourses extended 7.5—13 km from the discharge of effluents of the site mainly depending on mechanical and chemical processes. There were about 2.86 ha rice fields and 1.59 km stream sediments contaminated. Erosion of tailings and mining debris with little or no containment or control accelerated the contamination processes.