Multi‐residue analysis of sulfonamides in animal tissues by capillary zone electrophoresis with electrochemical detection

BACKGROUND: The objective of this study was to adapt and improve previously published analysis methods aimed at the simultaneous determination of sulfonamide residues in edible animal tissues by capillary zone electrophoresis with electrochemical detection. RESULTS: The effects of several factors such as the acidity and concentration of running buffer, the separation voltage, the applied potential and the injection time on CZE‐ED were investigated. Complete separation of six sulfonamides was achieved within 17 min by using 40 mmol L^?1 Na₂B₄O₇/25 mmol L^?1 KH₂PO₄ (pH 6.2) at an applied voltage of 18 kV. Excellent linearity was obtained over two orders of magnitude with the improved detection limits (S/N = 3) ranged from 1.7 × 10^?7 to 4.4 × 10^?9 g mL^?1 for all six sulfonamides in comparison with previous reports. A solvent extraction/centrifuge/evaporation procedure was used to extract sulfonamides from animal tissues, sample clean‐up and pre‐concentration of sulfonamides prior to CZE‐ED analysis. Good recoveries from 81% to 92% were achieved. CONCLUSION: Results obtained in this work indicated that the proposed CZE‐ED method was sensitive, rapid and simple for the simultaneous determination of sulfonamides in edible animal tissues. Therefore, the new faster and easy handling procedure provides an additional powerful tool that can be employed for the analysis of sulfonamide residues in foodstuff. Copyright © 2009 Society of Chemical Industry     

Preparation of Large Area Double-walled Carbon Nanotube Macro-films with Self-cleaning Properties

Double-walled carbon nanotube (DWCNT) macro-films with large areas, excellent flexibility and superhy- drophobicity are reported. The area of the macro-film is larger than 30 cm×15 cm, and this large film can be bended, or folded without any damage, and even can be tailored freely. After a simple modification of perfluoroalkysilane, the surface of the macro-film shows excellent superhydrophobicity with a water contact angle of 165.7±2 deg. and sliding angle lower than 3 deg., the prepared superhydrophobic f...     

聚合物流动分子水平的数值模拟

提出一种新的聚合物流动分子水平的模拟方法,即将流线有限元与分子模型的Brown动力学模拟相结合,求解聚合物复杂流动问题。编写了相应的计算程序,成功地对平行平板间的绕圆柱流进行了模拟。研究的流体介质为Oldroyd-B流体,该流体对应虎克哑铃分子模型的牛顿溶剂稀溶液。通过和采用本构方程的计算结果对比,对这一新方法进行了评价。     

一种新的无结构决策方法(AHM法)在城市投资方案决策中的应用研究

通过对新的无结构决策方法（——属性层次模型ＡＨＭ）的介绍,并对模拟数据进行应用研究,结果表明无结构决策方法是一种简洁有效的决策方法．由于它模型简单,算法简便,特别易于软件化用于各种决策系统,因而有着广泛的应用前景．     

大气等离子喷涂镍铬涂层界面缺陷形成分析及工艺调控研究

涂层/基体界面污染率是考核涂层质量的重要指标。针对某新型发动机机匣内壁镍铬涂层界面存在的严重污染问题,首先利用显微组织分析及物相分析手段确定了界面污染物主要成分为Al₂O₃。然后,进行多因素对比试验重现了界面污染现象,确定了污染物来源为喷砂过程中滞留在基体表面的砂砾,并结合零件尺寸及外形开展了喷砂工艺优化研究。研究结果表明：具有较大动能的砂砾会嵌入硬度较低的基体中,造成界面污染;减少砂粒撞击动能及增加清理时间,可有效地减小涂层/基体界面污染率。     

TiAl基合金固态焊接

研究了各种显微组织ＴｉＡｌ基合金材料之间自体固态焊接,实验结果表明,粗晶ＴｉＡｌ基合金与粗晶ＴｉＡｌ基合金作焊接对偶件时,在结合面上形成与基体组织不同的再结晶细晶组织。这种显微组织的差异及结合面上微孔隙的残存,导致焊接构件的断裂主要发生在结合面上,如采用粗晶ＴｉＡｌ合金与细晶双态组织ＴｉＡｌ基合金对焊时。由于细晶ＴｉＡｌ基合金具有较好超塑性变形能力。在热压力作用下此部分材料可镶嵌入焊接对偶另一侧,     

热变形TiAl基合金的超塑性行为

采用包套锻复合热机械处理技术,在Ti-33Al-3Cr合金中得到了平均名义晶粒尺寸为1μm的热变形显微组织材料在1000—1075℃及10×10－6—8×10－3S－1的应变速率范围内显示良好的超塑性,其应变速率敏感系数高达0．9;热激活能仅为250kJ／mol．在1075℃及8×10－5s－1下得到517％的超塑性拉伸延伸率．获得高的超塑性拉伸值的机理是,动态再结晶导致应变速率硬化     

A.niger2363—2^#产柠檬酸影响因素的研究

以选出的A.niger2363—2~#为柠檬酸发酵用试验菌,研究了糖源、糖浓度、氮源、氮浓度、培养初始pH值、培养温度,培养基灭菌前与后调pH值等因素对其产酸的影响,并确定了其最佳培养条件。实验发现培养基灭菌后调pH值优于灭菌前调。     

连铸初始凝固行为的热模拟研究

在归纳分析前人工作的基础上，通过热模拟试验和对振痕形貌、凝固组织的观测，研究了振痕凝固组织和初始凝固机理以及影响它们的重要工艺因素。