光度法测定微量铁(Ⅲ)——基于其对溴甲酚绿与溴酸钾氧化褪色反应的催化作用

在0.2 mol·L-1磷酸介质中,铁(Ⅲ)对溴酸钾氧化溴甲酚绿指示剂褪色具有强的催化作用,从而建立了一种催化动力学光度法测定铁的方法.试验结果表明:在440 nm最大吸收波长处,沸水浴条件下,时间控制在12 min时,△A(△A=A0-A)趋于稳定且最大.铁(Ⅲ)的线性范围在7.2～1 800μg·L-1内吸光度△A与铁(Ⅲ)浓度呈线性关系,检出限为6.8 μg·L-1.用于测定几种不同水样中微量铁(Ⅲ),所得结果与火焰原子吸收光谱法的结果一致.方法的回收率在95.5%～100.1%之间,测定值的相对标准偏差(n=6)在2.8%～4.0%之间.     

Push-pull alkenes by reacting N,N′-dimethyl cyclic ketene N,N′-acetals with isocyanates: synthesis, structures, and reactivities

N,N′-Dimethyl cyclic ketene N,N′-acetals react with two or three equivalents of isocyanates to generate tetrasubstituted push-pull alkene derivatives in one-pot sequential reactions. X-ray crystallography showed significant elongations and out of plane distorsions of the polarized carbon-carbon double bonds.     

基于固相基质的流动注射液滴荧光法对奎宁与盐酸普鲁卡因的快速检测

以葡聚糖凝胶为固相基质,结合流动注射技术建立了一种新型的液滴荧光法用于奎宁和盐酸普鲁卡因的快速检测.填充葡聚糖CMC-25微珠的离子交换柱用于奎宁和盐酸普鲁卡因的快速分离,基于二者均发射较强的内源荧光,采用液滴荧光法,结合固体基质流动注射分析法,对奎宁和盐酸普鲁卡因进行快速检测.在优化的实验条件下,奎宁和盐酸普鲁卡因的质量浓度分别在1.2×10-6 ～2.4×10-4 g/L和1.2×10-5 ～2.4×10-3 g/L范围内与体系的荧光强度呈线性关系,回归方程分别为IF=-2.92+2.50×106ρ和IF=6.26+1.03×105ρ,相关系数分别为0.999 5和0.989 3,检出限分别为1.0×10-6 g/L和1.1×10-5 g/L.该方法具有较高的灵敏度与选择性以及较好的精密度和重复性.将所建立的方法用于奎宁和盐酸普鲁卡因注射液的测定,回收率为97% ～102%,相对标准偏差小于2.5%.     

Steric effects on the enantiodiscrimination of diproline chiral stationary phases in the resolution of racemic compounds

Eight diproline chiral stationary phases with different end-capping groups were prepared and evaluated for the enantio-selective resolution of 41 racemic analytes. The end-capping group on the N-terminal of the peptide proved to be important as the chiral separation efficiency was decreased significantly without it. In general, increasing steric bulkiness near the N-terminal of diproline increases the enantioselectivity. Electronic structures of the end-capping groups are also important. One stationary phase with an adamantanecarbonyl capping group was found to provide both higher average separation and resolution factors than our previous leader. Three other stationary phases with 2-methylpropanoyl, cyclopropanecarbonyl and cyclobutanecarbonyl end capping groups were found to provide comparable average separation factor but higher resolution factors than our previous leader.     

全纯曲线的例外超平面∗

文章讨论了到复射影空间P^N (C)的全纯曲线交超平面的问题,借助Vandermonde行列式, 构造了一些具有N+1个例外超平面的非线性退化的全纯曲线和具有2N个例外超平面的线性退化的非常映射全纯曲线,说明了 Nochka 的全纯曲线的第二基本定理是最优的.最后还构造了具有2N个例外值的N值非常数代数体函数.     

LOB中基于工期决定因素分析的资源均衡算法研究

资源均衡是重复性项目中的经典调度问题,本文提出一种新的基于平衡线法(line of balance,LOB)的资源均衡方法。首先,本文提出LOB中关键路线的确定方法,确定关键路线及关键工序类型。而后,本文分析项目总工期的决定因素,对不同类型关键工序的特性及其与总工期、资源调整之间的关系进行了研究,论证了在LOB的资源均衡问题中,由于逆关键工序、点关键工序这些特殊工序的存在,可以在保证项目总工期不变的前提下,通过同时调整关键工序和非关键工序实现资源优化。按照这一思路,论文设计了LOB中资源均衡的遗传算法。算例分析表明该资源均衡算法的优化性能。本文提出的资源均衡思路和算法能帮助项目计划人员拓展资源优化空间,达到更好的资源均衡效果。     

南方某河水质荧光指纹特征及污染溯源

基于三维荧光光谱随荧光有机物的种类和浓度的不同与水体或污染排放源呈现对应关系的特性,水质荧光指纹溯源技术能够通过水体的三维荧光信号追溯污染排放源。以我国南方C市地表水A河为主要研究对象,利用水质荧光指纹溯源技术对A河及其上游来水方向J河进行了水质荧光指纹特征解析和污染排放源溯源。A河水质荧光指纹主要包括三个特征荧光峰,其[激发波长,发射波长]分别为[280, 320],[235, 345]和[255, 460] nm,其上、中、下游水质指纹之间相似度均大于99%,具有典型的印染废水污染特征。A河上游由J河分流汇入,J河水质荧光指纹与A河相似度低于60%,且强度不超过A河的40%。J河对A河水质荧光指纹形成过程的影响较小,A河的荧光强度主要由A河上游区域贡献。溯源结果表明,A河河水与A河上游印染纺织工业园区的印染废水水质荧光指纹相似度为94%,A河污染很可能来自其上游未经处理的印染废水的排放。A河和J河河水水质荧光指纹各荧光峰强度与高锰酸盐指数的线性相关系数R2分别达到0.956 4,0.937 5和0.985 4,而水质荧光指纹法感知污染的灵敏度更高。与其他三维荧光光谱相似度算法的结果对比表明,水质荧光指纹溯源技术是一种可靠的水环境监管技术,能够为进一步实现污染源头治理和环境精细化管理提供有力的技术支撑。     

Synthesis and Characterization of Nanostructured Fe3O4 Micron‐Spheres and Their Application in Removing Toxic Cr Ions from Polluted Water

We present a simple and effective method for the synthesis of nanostructured Fe₃O₄ micron‐spheres (NFMSs) by annealing hydrothermally formed FeCO₃ spheres in argon. The phase structure, particle size, and magnetic properties of the product have been characterized by X‐ray diffraction (XRD), Fourier‐transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), field‐emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and by means of a superconducting quantum interference device (SQUID). The results have shown that the as‐obtained NFMSs have a diameter of about 5 μm and are composed of nanometer‐sized porous lamellae. The NFMSs have a large specific surface area (135.9 m² g^?1), reductive Fe²⁺ incorporated into their structure, and intense magnetic properties. These properties suggest that NFMSs have potential application in removing toxic Cr⁶⁺ ions from polluted water. At 25 °C, each gram of NFMSs product can remove 43.48 mg of Cr⁶⁺ ions, as compared to just 10.2 mg for nanometer‐sized Fe₃O₄ and 1.89 mg for micron‐sized Fe₃O₄. The enhanced removal performance can be ascribed to the structural features. Moreover, the Cr⁶⁺ ion removal capacity of the NFMSs can reach up to 71.2 mg g^?1 at 50 °C. The influencing parameters in the removal of Cr⁶⁺ ions, such as contact time, pH, and temperature, have been evaluated. The Cr⁶⁺‐removal mechanism has been investigated. We have found that the NFMSs product not only serves as an effective adsorbent to remove toxic Cr⁶⁺ ions from polluted water, but also as an effective reductant in reducing the adsorbed toxic Cr⁶⁺ ions to much less toxic Cr³⁺ through the Fe²⁺ incorporated into its structure.     

药物分析(中国期刊)

对国内药物分析在2010～2011年的主要进展进行综述。内容包括高效液相色谱法、气相色谱法、毛细管电泳法、薄层色谱法、分光光度法和其它分析方法等。另外,对高效液相色谱法和气相色谱法的前处理方法、色谱柱、固定相以及不同联用技术进行分别评述,也对各种分析方法的应用领域、发展趋势等进行简要论述。     

Tailoring the charge carrier dynamics in ZnO nanowires: the role of surface hole/electron traps

Post-fabrication thermal-annealed ZnO nanowires (NWs) in an oxidizing (or a reducing) ambient were investigated using transient photoluminescence and X-ray photoelectron spectroscopy. Our findings reveal an ultrafast hole-transfer process to the surface adsorbed oxygen species (e.g., O(2)(-)) occurring within a few hundred picoseconds (ps) in the air-annealed samples; and an ultrafast electron-transfer process to charged oxygen vacancies (i.e., V(O)(2+)) occurring within tens of ps in the H(2)-annealed samples. Contrary to the common perception that the band edge emission (BE) dynamics are strongly influenced by the carrier trapping to the green emission related defect states (i.e., V(Zn)), these above processes compete effectively with the ZnO BE. Hole trapping by ionized V(Zn), which occurs in an ultrashort sub-ps-to-ps timescale (and hence limits its effective hole capture radius), however, has less influence on the BE dynamics. Importantly, our findings shed new light on the photoinduced charge transfer processes that underpins the novel properties of enhanced photocatalytic activity, photovoltaic performance, and photoconductivity response of ZnO NWs, thereby suggesting a strategy for tailoring the ultrafast carrier dynamics in ZnO NW-based devices.