Countercurrent approach to the enrichment of Δ9c,11t-and Δ10t,12c-18:2 isomers by urea complexation

CLA refers to a group of geometrical and positional isomers of linoleic acid. CLA has been shown to have potentially beneficial effects on cancer, atherosclerosis, and body metabolism in animals. Mixtures containing equal amounts of these isomers are commonly used in many research studies because of their greater availability and lower cost relative to pure isomers. This has hindered progress in elucidating the biological properties of specific isomers and their relevance in animal and human biology. A method was developed that offers a compromise between cost and utility to make available enriched mixtures of either the Δ9c,11t- or Δ10t,12c-18:2 isomers for use in a wide range of experimental applications. A countercurrent approach was developed to separate the Δ9c,11t- and Δ10t,12c-18:2 isomers from an equal mixture of these two isomers by urea complexation. After three successive rounds of complexation using an equal amount of CLA and urea, a fraction enriched in Δ9c,11t-18:2 containing 42.5 and 17.4% of Δ9c,11t-and Δ10t,12c-18:2, respectively, was recovered. After a single round of complexation using 2.5 g urea/g CLA, a fraction enriched in Δ10t,12c-18:2 was recovered containing 29.7 and 69.1% of Δ9c,11t- and Δ10t,12c-18:2, respectively.     

无铅压电陶瓷的研究进展

在压电陶瓷领域，无铅压电陶瓷从环保的角度考虑越来越引起人们的注意。本文主要综述了以BNT为基的3类无铅压电陶瓷体系。它们都是很好的无铅压电陶瓷的侯选材料，其中BNBT－6，BNTN－3和BNST－2的机电耦合常数K33分别为0．55，0．43，而且具有较高的频率常数和较小的介电系数，适用于众多高频超声换能检测领域以及压电致动装置等方面，所以作为无铅压电陶瓷它们是很有潜力的。     

β晶型聚丙烯的研究进展

对近年来在β晶型聚丙烯(PP)形态结构，影响β晶型含量的因素，β晶型成核剂，β晶型转变及β晶型PP性能等方面的研究工作进行了综述。添加成核剂可得到高含量的β晶型。与α晶型相比，β晶型PP的球晶尺寸大幅度减小，晶粒细化，具有良好的抗冲击性能和较高的热变形温度。     

Processing of High-Density Submicrometer Al2O3 for New Applications

Sintered corundum components with submicrometer grain sizes exhibit properties which enable numerous new applications. Wet powder processing is developed to associate minimum grain sizes at highest densities with the lowest population of macrodefects. A closest ratio of powder particle size and sintered grain size is important for obtaining most fine-grained microstructures. This target was approached best by using powders with particle sizes in the range of 100–200 nm rather than with smaller nanoparticles.     

碱式硫酸镁晶须的合成及应用

以一定浓度的MgSO4和NaOH溶液为原料,在常温下混合,在160℃,0.5 MPa的条件下用水热法反应8 h,制备出增强阻燃材料MgSO4.5Mg(OH)2.3H2O型碱式硫酸镁晶须(MOS),探讨了反应条件对产物形貌、结构及组成的影响,初步确立了制备MOS的工艺条件。经过对复合材料的拉伸性能测试得出结论,采用MOS填充改性的聚丙烯,优于市售纳米氢氧化镁和阻燃级氢氧化镁。     

浅谈国产化CO2汽提装置的相关问题

我国自20世纪70年代以来共引进了17套年产500～600kt的CO2汽提法大型尿素装置，1975年国内完成了年产240kt CO2汽提法尿素装置设计，并在上海吴泾化工厂建成投产，1991年又完成了日产140t CO2汽提法尿素装置设计，并在山东潍纺化肥厂、河北元氏化肥厂投产，标志着我国CO2汽提尿素工艺装置已基本实现了国产化。目前除液氨喷射器外，     

真空系统的工艺设计

介绍真空系统的基本概念、工艺设计及实际应用。     

利用粉煤灰生产SiC陶瓷原料

利用粉煤灰部分或全部代替石英砂,配以适量的锯末,在高温炉中特定的烧成制度下,采用SiO2-C还原法将粉煤灰中的二氧化硅与锯末中的碳结合制取高性能的SiC陶瓷原料。利用正交实验对合成工艺中的合成温度、保温时间、碳过量数进行了设计和探索性实验,并对合成产物中的碳化硅的含量进行了测试。研究表明,在经催化剂(FeCl26H2O)浸泡12小时,加入2%矿化剂,在1380℃的合成温度下,保温时间2小时,碳过量10%的情况下,生成的SiC陶瓷原料中SiC的含量在53.6%以上。     

化肥厂排水回用试验

本文介绍了太原化肥厂含盐量、悬浮物、ＮＨ３－Ｎ含量均较高的排水经简单、经济的工艺净中回用于工业冷却水的水质稳定模拟试验，结果表明，回用于工业冷却水过程中，水中微生物滋长的问题得到了良好的解决，在循环水含盐量达到１４６５４ｍｇ／Ｌ，总硬度达到８２７ｍｇ／Ｌ（以ＣａＣＯ３计）的情况下，系统内的腐蚀及结垢倾向得到了较好的控制。