COMPARISON OF VARIOUS CONJUGATE GRADIENT METHODS FOR INVERSE HEAT TRANSFER PROBLEMS

Many inverse heat transfer problems can be solved efficiently through the minimization of a performance function utilizing the conjugate gradient method. The gradient of the performance function needed in the minimization procedure of the conjugate gradient method is obtained by employing either the adjoint variable method or the direct differentiation method. In the present study we consider an inverse problem of estimating time-varying strength of a heat source in a two-dimensional heat conduction system, and compare the adjoint variable method and the direct differentiation method in terms of accuracy and computational efficiency, and finally suggest a new method that exploits the advantageous aspects of both methods while avoiding the shortcomings of them.     

Recent Developments and Applications of Ionic Liquids in Gas Separation Membranes

Flue gas emissions and the harmful effects of these gases urge to separate and capture these unwanted gases. Ionic liquids due to negligible vapor pressure, thermal stability, and wide electrochemical stability have expanded its application in gas separations. A comprehensive overview of the recent developments and applications of ionic liquid membranes (ILMs) for gas separation is given. The three general classifications of ILMs, such as supported ionic liquid membranes (SILMs), ionic liquid polymeric membranes (ILPMs), and ionic liquid mixed‐matrix membranes (ILMMMs) along with their applications, for the separation of various mixed gases systems is discussed in detail. Furthermore, issues, challenges, computational study, and future perspectives for ILMs are also considered.     

Carrageenan-guar gum microwave irradiated micro-porous interpenetrating polymer network: A system for drug delivery

A series of microwave irradiated IPN of Crg and GG have been synthesized and cross linking through hydrogen bonding was confirmed by FTIR spectroscopy. Thermal sensitivity at 48°C, degradation above 200°C is an emblem of uniqueness. We obtained micro rough surface morphology, hydrophilicity and muco-adhesion supporting S6 for targeted drug delivery. Honey comb like internal architecture will provide high mechanical strength. The sample S6 showed 72% drug release in 12 hours. Based on the results, it was concluded that the S6 can be used as target oriented controlled drug delivery devices enabling control over swelling and drug release.     

Determination of mechanical properties of polymeric microspheres used in controlled drug delivery systems by nanoindentation

In this study, we synthesized poly (vinyl acetate-co-divinyl benzene) microspheres with various monomer/cross-linker contents for oral/topical sustained drug release applications and determined the micromechanical properties by nanoindentation. Compression elastic moduli of materials were calculated by using the limited depth of indentation according to Hertz elastic deformation model and presented as the histogram of multiple data. In terms of drug release practices, poly (VAc-co-DVB) microspheres with a high DVB content, especially in topical applications, are expected to carry drugs under mechanical stresses of less than 1.0 GPa.     

基于智能高分子材料的灵敏检测技术研究进展

近年来,将智能高分子材料识别响应的微小刺激信号转化并放大为方便人们读取的信号检测技术成为研究热点。本工作综述了近年来基于智能高分子材料的灵敏检测技术的研究进展,重点介绍了将智能高分子材料识别响应刺激信号转化为电信号、流量信号和光信号的检测技术。最后讨论了基于智能高分子材料的灵敏检测技术应用时需解决的关键问题,为基于智能高分子材料的灵敏检测技术的设计与应用提供了有价值的参考。     

农科有机化学教学中的几个小方法

农业院校中的有机化学课程是一门重要的基础学科,教学涉及范围广,内容渗透多个学科。学好有机化学,能够为学生的学习深造和工作实践打下坚实的基础,具有非常重要的意义。笔者探讨了农科有机化学教学中的几个小方法,改善课堂教学效果,提高学生学习积极性。     

高分子表面活性剂的合成

以丙烯酸、丙烯酰胺和丙烯酸丁酯为单体,采用瞬时聚合法合成了高分子表面活性剂。表面活性研究表明,制备的高分子表面活性剂有良好的表面活性,表面张力可低至42 mN/m。红外光谱表明,产物没有发生交联,黏度法测定产物的分子量为2×104～4×104。     

手性铜试剂在羰基化合物加成反应中的应用

介绍了有机铜试剂具有价格低廉、毒性小、配位能力好等的优点,总结了有机铜试剂在不饱和羰基化合物的不对称共轭加成反应中的应用,特别是催化不饱和酯、硫酯、砜、醛和酮等α,β-不饱和羰基化合物的不对称共轭加成反应,提出了手性铜试剂催化不对称共轭加成反应在底物选择上仍然具有一定的局限性,该反应的底物主要集中于酮类化合物,而砜类和...     

An efficient method for nitration of aromatic compounds over solid acid and polymer‐supported sodium nitrite

A variety of aromatic compounds are nitrated under heterogeneous conditions using a polymer‐supported hydrochloric acid, [P₄‐(VP)]HCl, with a polymer‐supported sodium nitrite, [P₄‐VP]NO₂, or sodium nitrite in ethanol at room temperature with high yields. This methodology is useful for nitration of activated aromatic compounds. In this procedure, the work‐up is very easy, and the spent polymeric reagent can be regenerated and reused. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011