Application of integrated computational chemistry system to the design of inorganic membranes

Today inorganic membranes attract a lot of interest as a growing field. Main focus of those activities is on the development of membrane materials, which can offer high permselectivities with acceptable high permeances. The need for high permselectivity beyond those limited by Knudsen flow requires the estimation of the factors, which determine the permselectivity. Plausible theoretical models based on physical or chemical reasoning is desirable to guide systematic development efforts for designing next generation inorganic membranes. Here we reviewed our attempts to generate theoretical models based on the molecular dynamics method for this purpose. As a first attempt, simulation was performed at specific conditions where the Knudsen theory can be applied and can be reproduced well by our simulation methodology. Molecular dynamics simulation at 373 K of the permeation of iso- and n-butanes through ZSM-5 type silicalite membrane are presented. After 200 ps of simulation time the permeation of n-butane was observed whereas the permeation of iso-butane was not observed. The calculated permeability of n-butane, which is close to experimental data, is also presented. A study on the affinity membrane for the separation of CO₂ at high temperature is presented and the prospect of permselectivity of CO₂ is demonstrated.     

用流动可视化技术研究混合器内研究简报流场及混合效果

引言 不同流体的混合是化工、生物制品、食品工业等工艺过程中一道重要的工序,仅依靠流体在输送过程中的自然湍流扩散不能进行有效的混合,因此必须使用混合器,使液体在短时间内获得均匀的特性,达到满意的混合效果,并使损失的能量较小.不同行业由于介质性能和混合要求不同,相应混合器的结构也不同.通常国内外多采用经验类比法设计混合器,用取样分析法检验混合效果.随着新技术的发展,深入研究流体混合机理对于高效节能混合器的设计具有重要意义.     

Separation of AG function in floral meristem determinacy from that in reproductive organ identity by expressing antisense AG RNA

The Arabidopsis floral homeotic gene AGAMOUS (AG) is a regulator of early flower development. The ag mutant phenotypes suggest that AG has two functions in flower development: (1) specifying the identity of stamens and carpels, and (2) controlling floral meristem determinacy. To dissect these two AG functions, we have generated transgenic Arabidopsis plants carrying an antisense AG construct. We found that all of the transgenic plants produced abnormal flowers, which can be classified into three types. Type I transgenic flowers are phenocopies of the ag-1 mutant flowers, with both floral meristem indeterminacy and floral organ conversion; type II flowers are indeterminate and have partial conversion of the reproductive organs; and type III flowers have normal stamens and carpels, but still have an indeterminate floral meristem inside the fourth whorl of fused carpels. The existence of type III flowers indicates that AG function can be perturbed to affect only floral meristem determinacy, but not floral organ identity. Furthermore, the fact that floral meristem determinacy is affected in all transformants, but floral organ identity only in a subset of them, suggests that the former may required a higher level of AG activity than the latter. This hypothesis is supported by the levels of AG mRNA detected in different transformants with different frequencies of distinct types of abnormal antisense AG transgenic flowers. Finally, since AG inhibits the expression of another floral regulatory gene AP1, we examined AP1 expression in antisense AG flowers, and found that AP1 is expressed at a relatively high level in the center of type II flowers, but very little or below detectable levels in the inner whorls of type III flowers. These results provide further insights into the interaction of AG and AP1 and how such an interaction may control both organ identity and floral meristem determinacy.     

Crystal orientation and twinning in cold-rolled ultrahigh molecular weight polypropylene

The mechanisms of plastic deformation in cold-rolled ultrahigh molecular weight polypropylene (UHMWPP) have been explored by means of wide angle X-ray (WAXD) pole figures. The melt crystallized UHMWPP slabs were rolled unidirectionally in a two-roll mill at 408 K as well as in the cross (transverse) direction. In the unidirectional rolling, all reciprocal lattice vectors of (110), (040), and (130) were found to orient preferentially in the film normal (thickness) direction. The cross-rolling of UHMWPP shows the preferential orientation of the above plane normals in the film thickness direction, but the distribution of poles broadens toward the transverse direction. Such orientation behavior is very different from that of conventional cold-rolled polypropylene. Various orientation mechanisms involving the orientation of lamellae in the film plane, twinning of the (110) plane and slippage mechanisms have been taken into consideration to account for the observed pole figures. A theoretical simulation has been carried out based on an orientation distribution function approach by introducing a slippage angle along the maximum shear stress in conjunction with intralamellar slip around the transverse direction. This model simulation conforms closely with the experimental WAXD pole figures of the (110), (040), and (130) planes.     

Abnormal gastric motility in liver cirrhosis: roles of secretin

Cutaneous electrogastrography (EGG) revealed that the power ratio, an indicator of rhythmicity of EGG waveforms was significantly less in liver cirrhosis (power ratio: 28.2+/-14.5%) than in normal subjects (power ratio: 45.6+/-16.2%) (P < 0.01), thus demonstrating dysrhythmic EGG waveforms for liver cirrhosis. Gastric emptying time (T1/2), calculated from the half-life of retained radioisotope (RI) in the region of interest (ROI) in the stomach following the ingestion of RI containing test meal was significantly prolonged in patients with liver cirrhosis compared to the control (liver cirrhosis vs controls 43.2+/-20.3 min vs 24.8+/-9.6 min, P < 0.01). Of the five gastrointestinal hormones-gastrin, secretin, motilin, cholecystokinin (CCK), and glucagon-serum secretin was significantly higher in liver cirrhosis than the control (P < 0.05) and negatively correlated with the power ratio (r = 0.51, P < 0.01). Normal, regular EGG waveforms (power ratio: 47.1+/-10.2%) became dysrhythmic in normal volunteers (power ratio: 34.1+/-12.4%), when their serum secretin was experimentally increased to essentially that in liver cirrhosis and possible roles of hypersecretinemia in abnormal gastric motility in liver cirrhosis are proposed.     

Substation simulation system using virtual reality technology

An indoor distribution substation simulation system based on virtual reality technology has been developed. The system is designed to give the user the feeling of actually touring a substation for routine inspection. Various states of the substation facilities, such as the opening and closing of the doors and the disconnectors as well as the relocation and extension of the installations, can be simulated. In the event the user approaches the energized components of the equipment and fails to keep the specified insulation distance from them, the system first sounds an alarm, and then a flashing red light on the display warns of passage beyond the safety point and that the operation has suffered an electric shock. Validation of equipment operating procedures, training of unskilled workers and work-schedule preparation can be upgraded by using this system.     

A Universal Weighted Powed Function of Television Noise and Its Application to High-Definition Tv System Design

The author proposes a new weighted function of noise power affecting television picture defined in a two-dimensional picture frequency domain, including the vertical frequency domain. This function is of universal use and applicable to television standards with any aspect ratio and differing number of scanning lines.