固相微萃取技术用于牛奶中有机氯类农药残留的检测

建立了固相微萃取(SPME)-气相色谱-串联质谱(GC-MS/MS)同时测定牛奶中16种有机氯类农药残留的方法。对萃取模式、纤维涂层、萃取温度等实验条件进行了优化。用HP-5 MS弹性石英毛细管柱经柱程序升温技术分离,并用质谱检测器检测,外标法计算含量。待测农药的标准加入回收率在80%～110%之间,方法的相对标准偏差(RSD)≤9.6%,各农药组分的检出限为0.003μg/kg～0.15μg/kg。所测样品不含几种有机氯农药残留。本法简便、干扰小、检测效果好,可用于牛奶中有机氯类农药残留的检测。     

生色基团插层锌铝水滑石的制备和性质

以层状锌铝水滑石为主体, 在乙二醇介质中, 通过离子交换法, 将一对具有给体－受体性质的生色团香豆素-3-甲酸(3-CCA)与9-蒽甲酸(9-ACA)共插入到层状锌铝水滑石层间, 组装得到晶体结构良好的共插层类水滑石, 且通过控制离子交换的时间、温度、客体投料比, 可制得一系列具有不同摩尔比客体的共插层产物. 产物采用XRD、IR、TG-DTA等测试技术进行结构表征, 采用UV-Vis吸收光谱和荧光光谱研究其光谱特性. 结果表明, 给体受体进入层间后, 不仅客体与主体层板存在静电力和氢键相互作用, 而且在限域空间内有利于客体之间的相互作用, 从而产生了给体受体间的能量转移过程.     

On the electro-osmotic flow in a saturated porous medium

Electro-osmosis in a saturated porous rigid medium is studied by both theoretical and experimental approach. Relationships giving liquid and electrical coupled macroscopic flows are obtained from the homogeneization method. They point out possible non symmetrical cross effects that explain deviations from Onsager reciprocal relations. Experiments on a kaolinite are reported which exhibit an important non symmetrical coupling.     

Hamilton's law of variable mass system and time finite element formulations for time‐varying structures based on the law

Traditional principles of mechanics are primarily conceived for constant mass systems, which are only valid if mass is gained or lost at null velocity with respect to an inertial reference frame for variable mass systems, thus the numerical algorithms for time‐varying structures based on these principles are only suitable for this special case. In this paper, Hamilton's law of variable mass system is derived based on Meshchersky's fundamental equation, and two classes of novel time finite element formulations for linear systems with arbitrary continuous time‐varying parameters are developed based on the previous law. The formulations are verified extensively through numerical examples in which the convergence and effectiveness of algorithms are evaluated. Numerical examples demonstrate that compared with the algorithms for time‐varying structures that developed based on traditional principles of mechanics, the proposed algorithms provide extended capabilities in both time‐varying mass problems that mass is gained or lost at any velocity (such as rocket problem) and moving‐mass problems (such as vehicle‐bridge interaction problem) besides the time‐varying stiffness and damping problems, the proposed algorithms have a wider range of application. In particular, Hamilton's law of variable mass system provides a solid theoretical foundation for further research on the algorithm design for time‐varying structures. Copyright © 2014 John Wiley & Sons, Ltd.     

输气管道砂冲蚀的模拟实验

针对输气管道受携砂冲蚀磨损的监测问题,设计并组装了其模拟实验装置,以空气和石英砂模拟天然气携砂,用Q235、Monel400、GH3625三种材料制作受冲蚀元件,研究不同砂量冲蚀作用下元件的壁厚损失、质量损失和表面形态及其耐磨特性。结果表明:冲蚀元件的中间棱首先被冲蚀,且砂粒冲击后并未向后反弹而是在后续颗粒作用下滑向两侧,使得棱上出现横向滑擦;冲蚀元件正壁面受砂粒连续冲击产生压坑,压坑金属组织在挤压作用下向周围偏向堆积,最终呈块状剥落;冲蚀元件底部受砂粒冲击与塑性变形的共同作用变形最严重;经冲蚀后元件左右两壁面的壁厚损失不尽相同,且其棱部损失量普遍小于左右壁面损失量;耐冲蚀特性:GH3625最好,Monel400次之。这有助于输气管道携砂量预测的深入研究与冲蚀监测探针原材料的比选。     

Electrical conduction mechanism in solution grown doped polyvinyl pyrrolidone films

A detailed study of electrical conduction mechanism in bimetallized ferrocene-doped polyvinyl pyrrolidone films was carried out. The measurements were carried out on films of about 20 μm thick, in the field range of (2.0–8.0) x 10⁴ V/cm at temperatures ranging from 363 to 423 K. An investigation of the effect of impurity such as ferrocene in the polymer matrix was undertaken. Lowering of activation energy and increase in current due to doping were observed. The results showed that the charge carriers were generated by field-assisted lowering of coulombic barriers at the traps and were conducted through the bulk of the material by a hopping process between the localized states by a Jonscher-Ansari modified Poole-Frenkel mechanism. The dependence of current and activation energy on the ferrocene concentration is explained on the basis of charge transfer type of interaction between dopant and polymeric material.     

CO2套管式气体冷却器设计及试验研究

设计开发一台名义制热量为4．5kW的CO2套管式气体冷却器,并在CO2换热器性能试验装置上进行试验研究。试验结果表明,利用Petukhov—Popov—Kirilo传热关联式设计计算结果与试验结果一致性较好,偏差小于10％。     

生物质热解研究的进展

通过分析生物质热解的物理特性和运行条件,采用动力学模型和传热、传质模型,对生物质热解进行描述。     

我校“传热学”重点课程建设思路及教学设计探讨

在介绍学校"传热学"课程的内容、性质、特点、课程发展的历史沿革等相关内容的基础上,确立了课程建设的目标和方案,提出了重点课程建设的思路和设想,并对课程的教学设计进行了探讨,为重点课程的建设明确了方向.