N1取代基结构对菲并咪唑荧光色纯度的影响

以1,2-二苯基菲并咪唑(PPI)为模型化合物, 通过改变N1苯环上取代基结构制备了2类PPI衍生物, 并采用核磁共振谱对其化学结构进行了确认. 通过对PPI及其衍生物的单分子荧光光谱精细结构的分析, 比较了取代基位置和结构的变化对菲并咪唑类化合物荧光过程中发射主峰精细振动结构及所占比例的影响. 其中, N1链接苯环中R4位的取代基效应最显著, 当引入推电子或弱的吸电子取代基时, 菲并咪唑类衍生物的低能级发射比例降低, 荧光色纯度提高; 当引入强吸电子取代基时, 低能级发射比例增加, 光谱半峰宽加大. 本文结果为菲并咪唑基“蓝光”材料的设计提供了一定数据的支持与科学依据.     

气相色谱-质谱法测定油炸淀粉类食品中的丙烯酰胺

 建立了油炸淀粉类食品中丙烯酰胺的溴衍生化气相色谱-质谱(GC-MS)测定方法。样品经水提取、高速离心、石墨化 炭黑柱净化、溴衍生化后,以GC-MS选择离子进行定性,同位素稀释技术定量。该方法的检出限为5 μg/kg,回收率为90％ ～105％,相对标准偏差为6.3％。利用该方法对市场上某些油炸淀粉类食品进行了初步测定,发现薯片和炸薯条中含有27 8~4518 μg/kg的丙烯酰胺。     

Antibacterial poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) fibrous membranes containing quaternary ammonium salts

In this study, antimicrobial membranes based on biodegradable material poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) [P(3HB‐4HB)] and quaternary ammonium salts (QASs) by two methods have been performed. Three QASs with varied alkyl chain lengths have been synthesized successfully and characterized by ¹H nuclear magnetic resonance and Fourier transform infrared. The synthesized QASs were blended with P(3HB‐4HB) and electrospun into composite fibrous membranes or casted into conventional membranes. Electrospun fibrous membranes with large surface areas are a superior type of antimicrobial biomaterials, and they exhibit preferable properties than solution casting membranes. Specifically, electrospun fibrous membranes are tougher and can inactivate both Gram‐positive Staphylococcus aureus and Gram‐negative Escherichia coli O157:H7 in a contact time of 30 min, whereas the solution casting membranes cannot. The length of alkyl chain in the quaternary ammonium groups on the modified P(3HB‐4HB) membranes is able to influence the antimicrobial activity. This type of antimicrobial material may have potential applications in biomaterial field. Copyright © 2016 John Wiley & Sons, Ltd.     

A vertex‐centered linearity‐preserving discretization of diffusion problems on polygonal meshes

This paper introduces a vertex‐centered linearity‐preserving finite volume scheme for the heterogeneous anisotropic diffusion equations on general polygonal meshes. The unknowns of this scheme are purely the values at the mesh vertices, and no auxiliary unknowns are utilized. The scheme is locally conservative with respect to the dual mesh, captures exactly the linear solutions, leads to a symmetric positive definite matrix, and yields a nine‐point stencil on structured quadrilateral meshes. The coercivity of the scheme is rigorously analyzed on arbitrary mesh size under some weak geometry assumptions. Also, the relation with the finite volume element method is discussed. Finally, some numerical tests show the optimal convergence rates for the discrete solution and flux on various mesh types and for various diffusion tensors. Copyright © 2015 John Wiley & Sons, Ltd.     

AN/St悬浮共聚体系中AN在水/油两相间分配及其对共聚物组成的影响

研究了丙烯腈/苯乙烯(AN/St)悬浮共聚体系中AN在水/油两相间的分配及其对AN/St共聚物组成的影响.结果表明,AN分配于水/油两相间,使油相AN的含量低于相同单体配料比的本体聚合,导致生成的AN/St共聚物组成偏离本体共聚.为了准确预测进而控制AN/St悬浮共聚物的组成,提出了在考虑AN相分配的基础上计算AN/St悬浮共聚物组成的模型.计算结果与实验值一致,计算中用到的油相实际竞聚率与本体聚合相同,但该悬浮聚合的表观竞聚率随水/油比的变化而发生较大改变.     

三种蒙药中十二种微量元素的ICP- AES法分析

为研究蒙药药效与微量元素之间的关系,采用湿法消化,用ICP - AES测定了蒙药希莫音满都拉、哈日嘎布日- 10、阿拉坦-5中钙、磷、铜、钾、铁、钠、锰、锌、镁、锡、硅、钛的含量;同时做了精密度及回收率实验.结果表明,测定方法的标准偏差＜5％,回收率在92.8％～104.1％之间;3种蒙药中12种微量元素含量丰富,测定...     

Analysis of doxorubicin uptake in single human leukemia K562 cells using capillary electrophoresis coupled with laser-induced fluorescence detection

The doxorubicin (DOX) uptake in single human leukemia K562 cells with changes in both drug dosage and exposure period was studied using capillary electrophoresis (CE) coupled with laser-induced fluorescence (LIF) detection. The cells were treated with DOX at different concentrations (1, 3, 10, 20, 30, and 50 μM) and for different exposure times (1, 3, 5, 24, and 48 h). At least 20 cells were analyzed for each DOX-treated cell population. A marked heterogeneity in DOX uptake among single cells was observed, because the relative standard deviation of the uptake of DOX by single cells ranged from 24.0% to 61.1% within each cell population. The cell-to-cell heterogeneity in DOX uptake first decreased and then became constant with increasing drug concentration, but it did not exhibit regular variation with increasing exposure time. The mean DOX uptake was a linear function of drug concentration (r ≥ 0.9667). In terms of the correlation with exposure time, the mean DOX uptake reached its maximum at 3 h for the cell populations treated with 1–10 μM DOX, while it kept increasing during 48 h exposure of cell populations to 20–50 μM DOX. Because it eliminates DOX fluorescence quenching and sample loss, the CE-LIF method directly detects the true DOX uptake by single cells, and thus presents accurate information on both the cell-to-cell heterogeneity in DOX uptake and the patterns of DOX uptake in K562 cells as functions of drug concentration and exposure time.     

THE EFFECT OF PHOTO-CROSSLINKING ON THE ORIENTATION STABILITY OF POLYVINYL ALCOHOL CONTAINING 4-NITRO-4′-ALKOXYSTILBENE AND CINNAMYL PENDENT GROUPS*

Crosslinking is one of the effective routes for improving the orientation stability of poledpolymer films. The derivative of polyvinyl alcohol containing 4-nitro-4'-alkoxystilbene andphoto-crosslinkable cinnamyl groups as side chains has been synthesized. The in-situ simul-taneous photo-crosslinking poling of synthesized polymer films has been performed. Thesecond order nonlinear optical coefficient d_(33) of poled film is 11 pm/V. The SHG mea-surements show that the break-over temperature of SHG signal is raised obviously afterirradiation, its orientation stability is doubled as compared with that of non-crosslinkingsamples.     

Two multi-copper-containing heteropolyoxotungstates constructed from the lacunary Keggin polyoxoanion and the high-nuclear spin cluster

Two novel high-nuclear copper-substituted polyoxometalates, Na16[Cu14(OH)4(H2O)16(SiW8O31)4].20.5H2O (1) and K10Na14[Cu10(H2O)2(N3)4(GeW9O34)2(GeW8O31)2].30H2O (2), containing 14 Cu2+ ions and 10 Cu2+ ions, respectively, have been obtained in aqueous solution and characterized by IR, UV, TG, element analysis, electrochemistry, and single-crystal X-ray analyses. The polyoxoanion framework of 1 is composed of four [beta-SiW8O31] units connected by 14 Cu2+ ions to constitute a tetrameric compound. In 2, two [beta-GeW8O31] anions and two [B-alpha-GeW9O34] anions are connected together by a [Cu10(N3)4O32(H2O)2] {Cu10(N3)4} cluster to construct a novel tetrameric compound. The results of the electrocatalytic experiments reveal that the reduced species of 1 and 2 have electrocatalytic activities for nitrate reduction.     

Co-POM@MOF-derivatives with trace cobalt content for highly efficient oxygen reduction

A simple and effective method for constructing highly efficient oxygen reduction catalysts with trace amount of isolated cobalt was firstly developed by the pyrolysis of Co-centered polyoxometalate@metalorganic framework （Co-POM@MOF）.The Co-centered polyoxometalate ([Co W₁₂O₄₀]^6-) was confined in the well-defined void space of ZIF-8 to achieve homogeneous dispersion of polyoxoanions,where the isolated Co centers were well surrounded by the W-O shell and ZIF-8 fra...