改性催化裂化催化剂研究进展

对催化裂化催化剂的活性组分Y型分子筛的脱铝改性及抗重金属污染改性方法和改性后的含Y型沸石的性能进行了详细介绍。重点介绍了经特殊改性的催化裂化催化剂在脱硫、多产柴油及多产丙烯等方面的用途,指出应在现有技术基础上重点开发性能更为优良的多用途催化裂化催化剂。     

Synthesis of polyethylene oxide end‐capped with perfluoroalkyl groups/polystyrene prototype brushes

Polystyrene (PS)/poly(ethylene oxide) (PEO) prototype brushes were prepared by alternating free‐radical copolymerization of methacryloyl‐terminated PS and α‐vinylbenzyl‐ω‐hydroxy or α‐vinylbenzyl‐ω‐perfluoroalkyl (R_f) PEO macromonomers with the addition of Lewis acid (SnCl₄). It was found from their dilute‐solution properties that PS/PEO end‐capped with R_f (PBR_f), and PS/PEO having OH groups at terminal ends (PBOH) prototype brushes formed a single molecule in benzene and aggregates in chloroform, respectively. However, the brush PBOH formed a single molecule in N,N‐dimethylformamide. Such aggregation behaviors seemed to be caused by the interaction between hydroxy groups of PEO chain ends. The brush PBOH was also converted into PBR_f‐type brush by chemical modification, using corresponding acid chloride. The substitution of R_f groups was ～70% due to slipping of terminal hydroxy groups into PEO internal domains. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 772–778, 2006     

包结拆分在手性药物分离中的机理与应用

对外消旋体药物进行分离拆分是获取手性药物的重要方法。探讨了环糊精体系包结拆分法的机理，并对运用其机理于手性药物分离中的应用作了探讨。     

分子蒸馏技术与日用化工(Ⅰ)——分子蒸馏技术的原理及特点

介绍了分子蒸馏技术发展简况，并从分子运动平均自由程的定义出发，介绍了分子蒸馏技术的基本原理、特点以及与常规蒸馏、超临界萃取与层析分离等方法的不同。分子蒸馏操作温度低、受热时间短及分离效率高，特别适用于热敏性物质的提纯，有广阔的应用前景。     

Modelling of solvent positions around polar groups in proteins

Previous analysis of the distribution of experimental solventmolecule positions around amino acid side chains showed thatdistinct clustering occurred close to polar or charged atomsin proteins. We have used those data to predict likely solventpositions around proteins not used in our initial analysis.We envisage that this algorithm, AQUARIUS, will be useful forfinding solvent positions in electron density maps generatedby protein crystallography and as useful starting positionsfor solvent molecules in computer simulation studies of macromolecules.     

Elastohydrodynamic theory for wet oblique collisions

This paper presents a model for oblique collisions of spherical particles with a plane surface covered with a thin liquid layer. Elastohydrodynamic theory developed previously for fully immersed collisions [Davis, Serayssol and Hinch 1986 JFM 63 479-497] is modified for the normal component of motion to account for the finite thickness of the liquid layer. The resulting time evolution of the film thickness profile is then used along with sliding lubrication to determine the tangential component of motion. The critical Stokes number (dimensionless ratio of particle inertia and viscous forces), below which no rebound is seen, is predicted in terms of the physical properties of the materials involved in the collision, as described by a compliance parameter representing a dimensionless measure of elastic deformation due to viscous forces. Beyond the critical Stokes number, the normal restitution coefficient is found to increase with the Stokes number and the compliance parameter, asymptoting to the dry restitution coefficient at high Stokes numbers. The lubrication suction resistance during rebound is limited by cavitation. The tangential restitution is independent of the impact angle and is linearly dependent on the ratio of the fluid layer thickness to the sphere radius, in addition to depending on the Stokes number and compliance parameter. The tangential restitution is found to be close to unity and is generally higher for a larger value of the compliance parameter. Moreover, the tangential restitution is seen to increase with the Stokes number at small compliance and decrease with the Stokes number at large compliance. The change in rotational velocity exhibits trends that are the reverse of the tangential restitution. Finally, closed-form expressions have been developed for describing the restitution coefficients and dimensionless change in rotational velocity.     

强碱树脂在木糖应用中存在的问题及解决方法

木糖是一种在化工、食品等领域有着广泛用途的五碳糖,工业生产是用稀强酸将玉米芯中含有的大量多缩戊糖分解为单个的木糖分子,然后通过离子交换除盐、脱色,精制提取,但在强碱离子交换柱中,木糖分子容易被部分催化异构转化为阿拉伯糖,使得木糖纯度下降,结晶困难。考察了强碱树脂再生浓度、淋洗终点pH值、交换温度以及流速对木糖分子异构的影响,得出最佳的交换工艺条件:再生剂浓度为2%、淋洗终点pH值为7.5、交换温度20℃,流速为1BV/h。     

季戊四醇的超分子化学

介绍季戊四醇的超分子化学,包括超分子网状结构、螺环冠醚、非常规液晶、富勒烯衍生物、固相光催化反应、Janus树枝状分子等等。     

Molecular beam studies of fullerenes

A number of molecular beam experiments with the fullerenes are described. Such experiments allow a detailed probing of the interactions between fullerenes and other species and among the fullerenes themselves. Emphasis is placed on work involving photophysics and collisional interactions of the fullerenes.     

分子荧光光度法测定面粉中的核黄素

采用分子荧光光度法测定三种面粉中的核黄素。最佳实验条件为：核黄素的最大激发波长和最大发射波长分别为449nm和525 nm;确定最佳的提取液种类、体积和时间等条件。核黄素在二个数量级的范围内呈良好线性关系,该方法成功的被应用于实际样品的分析,获得令人满意的结果.