TurboFlow在线净化/液相色谱-串联质谱法快速测定动物源性食品中聚醚类抗生素的研究

建立了Turbo Flow在线净化/液相色谱-串联质谱法快速同时测定牛奶、鸡肉和鸡蛋中拉沙洛菌素、盐霉素、莫能菌素、甲基盐霉素、马杜霉素和尼日利亚菌素残留的方法。样品提取液经在线净化柱Cyclone-p净化,Thermo Scientific Hypersil-Gold C8(150 mm×2.1 mm,5μm)色谱柱分离,电喷雾正离子模式测定,整个分析过程仅13 min。方法在1~100μg/L范围内呈良好线性关系(r≥0.999),定量下限为1μg/kg,在动物源性食品中3个加标水平下的回收率为71.9%~109.0%,相对标准偏差为1.5%~14.9%。     

A semi-empirical approach to determine gamma activities in environmental cylindrical samples

A semi-empirical method to determine radionuclide concentrations in large environmental samples without the use of reference material and avoiding the typical complexity of Monte-Carlo codes is proposed. The calculation of full-energy peak efficiencies was carried out from a relative efficiency curve (obtained from the gamma spectra data), and the geometric (simulated by Monte-Carlo), absorption, sample and intrinsic efficiencies for energies between 130 and 3000 keV. The absorption and sample efficiencies were determined from the mass absorption coefficients, whereas the intrinsic efficiency was approximated by an empirical function. The deviations between calculated and experimental efficiencies for a reference material in most cases are less than 10%. Radionuclide activities in marine sediment samples calculated by the proposed method and by the experimental comparative method were not significantly different. This new method can be used for routine environmental monitoring when uncertainties up to 10% are acceptable.     

Modified Brans–Dicke theory of gravity from five-dimensional vacuum

We investigate, in the context of five-dimensional (5D) Brans–Dicke theory of gravity, the idea that macroscopic matter configurations can be generated from pure vacuum in five dimensions, an approach first proposed by Wesson and collaborators in the framework of 5D general relativity. We show that the 5D Brans–Dicke vacuum equations when reduced to four dimensions (4D) lead to a modified version of Brans–Dicke theory in 4D. As an application of the formalism, we obtain two 5D extensions of 4D O’Hanlon and Tupper vacuum solution and show that they lead two different cosmological scenarios in 4D.     

江西宜黄中华秋沙鸭自然保护区鱼类资源初步调查

2012年7月,对江西宜黄中华秋沙鸭自然保护区的鱼类资源展开初步调查。结果显示,该保护区分布有鱼类4目7科25种,兴凯鱊、棒花鱼、鲫为优势种,且渔获量丰富、鱼类个体较小。同时分析了保护区面临的潜在威胁,并提出了相应的保护措施。更多还原     

菌紫质中视黄醛超快异构化反应的动态光谱分析

利用飞秒时间分辨吸收光谱方法研究了菌紫质(BR)光循环中视黄醛超快异构化反应过程. 发展了结合全局拟合的奇异值分解(SVD)分析方法, 建立了超快异构化反应动力学模型, 解析了几个重要的中间态I460, J625和K590的物种相关差异光谱(SADS)和布居动力学, 确定了光致异构化反应过程. 同时明确了700 nm附近存在的受激荧光来自于弗兰克-康登跃迁态(H中间态)的贡献, 其衰减寿命为0.04 ps. 这些结果对深入认识H态在超快异构化反应过程中的作用具有参考价值.     

聚甲基丙烯酸甲酯/苯乙烯-丙烯腈无规共聚物薄膜表面原位原子力显微镜相图

采用原位原子力显微镜在线跟踪方法,研究了聚甲基丙烯酸甲酯/苯乙烯 丙烯腈无规共聚物共混体系表面相分离行为,得到了具有下临界共溶温度（临界温度约为175 ℃）原位相图。 与文献报道的用离位方法所得结果的主要差别是原位的临界相分离温度稍有提高,以及离位结果中存在的组成对称性。 这些差别主要来源于离位和原位实验方法上的差别,薄膜厚度减小导致的相容性,热力学历史的变化以及基底效应的加剧。     

Determination of aniline by adsorptive stripping voltammetry using an improved diazotization and coupling procedure application to the evaluation of the light degradation of D&C red no. 33 in the presence of ascorbic acid

A method for the determination of aniline was developed, based on the diazotization and coupling of the aromatic amine to form an azo compound capable of being determined by adsorptive stripping voltammetry. A fast derivatization procedure was developed using 1-naftol as the coupling agent. A detection limit of 0.8 mug/l was obtained for aniline, using an accumulation time of 2 min. The method was applied in the determination of the amount of aniline in the colouring matter D&C Red No. 33, after a liquid-liquid extraction with chloroform, before and after submitting the colouring matter to a process of degradation, using accelerated light conditions in the presence of ascorbic acid.     

基于对数灰关联度的IOWGA算子最优组合预测模型

本文将对数灰关联度和IOWGA算子相结合,提出一种基于对数灰关联度的IOWGA算子最优组合预测模型,并定义了优性组合预测的概念,最后通过对税收收入进行组合预测说明该组合预测方法的有效性和合理性,且该模型存在优性组合预测。     

稀土(镧)硫醇盐的合成与表征

以三氧化二镧为原料, 经过醇化, 制备了三(月桂硫醇)镧及三(巯基乙酸异辛酯)镧, 并对合成方法进行了优化. 采用热失重分析、FTIR光谱、感应耦合等离子色谱、元素分析和1H NMR对目标产物进行了表征. 确定合成稀土异丙醇盐最佳反应条件为: 反应温度80 ℃, 反应时间2 h; 合成三(月桂硫醇)镧的反应条件为反应温度110 ℃, 反应时间2 h, 月桂硫醇的摩尔分数过量24％; 合成三(巯基乙酸异辛酯)镧的反应条件为反应温度60 ℃, 反应时间2 h, 月桂硫醇过量32％.