A NOVEL METHOD FOR FABRICATING COMPOSITE MOSAIC MEMBRANE WITH UNIQUE NF SELECTIVITY

A novel method of fabricating composite mosaic membranes was studied on the basis of interracial polymerization （IP） by coating a thin selective layer onto the surface of a micro-porous hollow-fiber membrane, in which, 2,5-diaminobenzene sulfonic acid was used as one monomer of the IP reaction, and a mixture of trimesoyl chloride （TMCI） and 4-（chloromethyl） benzoyl chloride as the other monomer. Through the IP reaction a thin selective layer with negatively charged groups could be first formed on the polyethersulfone （PES） support membrane. Then trimethylamine solution was introduced to modify the IP layer through a quaternization reaction. Thus the selective layer of this composite membrane contained both negatively charged and positively charged groups to perform the mosaic functionality. Characterization of the composite mosaic membranes was carried out through permeation experiments using different inorganic salts and dyes. The experimental results showed that the membranes could permeate both mono- and bi-valent inorganic salts, but reject larger organic molecules. Such a mosaic membrane is potentially useful for the separation of salts from water-soluble organics, especially in dye and textile industries.     

圆形区域内香枞芽虫的分布模型

本文讨论圆形区域内芽虫分布模型,特别研究了芽虫与天敌接触时产生与避免outbreak状态的可能性。     

Toward phenanthridin-2-ylidene: electrophilicity versus acidity in planar-constrained C-aryl iminium salts

A phenanthridinium salt was prepared in four steps, including an intramolecular CH-arylation and a hydride abstraction reaction. Treatment with sterically demanding bases does not lead to the corresponding carbene, but rather to addition products: the planar-constrained geometry significantly enhances the electrophilicity over the acidity of C-aryl iminium salts.     

三大支柱与纺织品贸易

对于中国和欧盟来说,刚刚过去的5月份实在是太不寻常了:中欧建交30周年;法荷两国否决“欧宪”使欧盟陷入极度困境中;中欧纺织品贸易摩擦热度烫人。这几件事,足以吸引全世界的眼球。当然,人们也会探寻其间的关联……6月7日,由中国人民外交学会、《世界知识》杂志和欧盟驻华代表团共同主办的“中欧经贸论坛2005”在北京钓鱼台大酒店举行。本栏目的大部分文章来自于论坛上的发言(有所删节)。其余精彩发言我们将陆续刊出。———编者     

Signal generation and spatial resolution in scanning electron acoustic microscopy

The thermal conduction and Navier-Stokes equations are usedto obtain the stress field generated by a chopped electron beam incident ona disk sample.The piezoelectric equation is then used to obtain the out-put signal of the transducer coupled to the sample.The results lead to aconsideration of the signal generation mechanism and spatial resolution inscanning electron acoustic microscopy(SEAM).It is shown that atime-variant heat source generated both a thermal wave and an acousticwave simultaneously,and thermal-to-acoustic wave mode conversion oc-cured on the boundary surfaces depends on the amplitudes and the gra-dients at boundary surfaces of both heat source and thermal waves.It isargued that the spatial resolution of a imaging system operated in thenear field,such as SEAM and thermal wave microscope,is dependent onthe distance between the heat source and scatterer and,at best,the lateralresolution in SEAM is of the order of the diameter of the focal spot ofthe electron beam.     

海龟与大堡礁

在旅游与环境保护之间,大堡礁已被确认为环境保护方面的楷模。它取得了微妙的平衡。尽管如此,澳大利亚当局仍保持着警惕……大海龟总算接近了她漫长旅途的终点。     

无格式设计观

当 Kjell Ekhorn 还在学校学习图形设计,Jon Forss 已在这个行业里工作了不少年头。1989年 Jon Forss 于1LeicesterPolytechnic 毕业后就在 Bath 为一家广告代理商工作,四年之后他移居伦敦为 namara 设计公司设计图书封面。五年以后,他遇到从伦敦 Centrl St.Martins 学校毕业不过两年,正以自由职业者身份从事图书封面设计、图片制作和摄影工作的 Kjell Ekhorn。两人惊讶于互相对图书封面设计的看法,一时相见恨晚,然后自然而然的开始了两人合作的NON-FORMAT 时代。     

Some hydrodynamic aspects of 3-phase inverse fluidized bed

Hydrodynamics of 3-phase inverse fluidized bed is studied experimentally using low density particles for different liquid and gas velocities. The hydrodynamic characteristics studied include pressure drop, minimum liquid and gas fluidization velocities and phase holdups. The minimum liquid fluidization velocity determined using the bed pressure gradient, decreases with increase in gas velocity. The axial profiles of phase holdups shows that the liquid holdup increases along the bed height, whereas the solid holdup decreases down the bed. However, the gas holdup is almost uniform in the bed.     

学了统计学可以有什么样的作为?(续)──介绍统计学的特点和用处

Ⅲ、统计学家是做什么的? 为了描述统计学家工作的各个领域,最好的方法是给出大量的事例.限于篇幅,这里叙述六个事例.第一个事例描述统计学家的一个新的且很有希望的出路,就是在私人单位里当顾问.许多统计学家例如大学里的那些统计学家,在个人的部分时间从事于这种顾问工作. 经历1 A.B.先生与几个公司和研究所一起工作.几乎每周一次,每次花两到四小时与他的委托人中的每一个人联系,虽然他极少看见他们中的一些人.他与他们中的许多人每天都要通过电话谈话.他经常研究他们的问题,并且为了进行工作他或者重复写他的指示或者根据研究的结果所进…     

高效液相色谱死体积的热力学定义

本文讨论了高效液相色谱死体积的定义和如何以吉布斯热力学理论为基础对其测定。推荐的热力学理论方法能应用于任何一种液相色谱方法,如正相、反相、离子交换、甚至体积排斥色谱。提出了一种能在整个浓度范围内准确计算流动相组分干扰峰死体积的方法。对某些化合物容量因子出现负值也作了解释。