Kinetics of sol-to-gel transition for poloxamer polyols

Kinetics of gelation for aqueous solutions of poloxamers 407 and 288 were determined using pulse shearometry. The principle of this method for determining the shear modulus of a semisolid was based on generation of a torsional force that is transmitted through the poloxamer sample at discrete time intervals. Three distinct linear phases were observed for the log dynamic shear modulus (G′) vs. time profiles as poloxamer 407 and 288 solutions of varying concentrations were allowed to passively warm at room temperature to a temperature exceeding the sol-to-gel transition temperature, T_m. The beginning of the second exponential phase coincided with the onset of the gelation process as determined by visual observation. Although gelation appeared visually to be complete at the beginning of the third exponential phase of the log G′ vs. time profiles, this last exponential phase may indicate the rate of formation of the polymer network. A comparison of poloxamer 407 [30% (w/w); T_m = 10.9°C] and poloxamer 288 [37% (w/w); T_m = 11.1°C] would suggest that the concentration of poloxamer required to achieve approximately the same gelation temperature for poloxamers having a similar ratio of poly(oxypropylene):poly(oxyethylene) units decreases with increasing molecular weight of the poly(oxypropylene) hydrophobe contained in the copolymer. Results of these preliminary studies suggest that the gelation process was significantly (p < .05) more rapid for poloxamer 407 at a 30% (w/w) concentration compared to a 30% (w/w) solution of poloxamer 288 when the poloxamer solutions were allowed to passively warm at room temperature. In addition, it appears that the rate of gelation for the poloxamer solutions studied was dependent on the rate of heat transfer through the polymer solution.     

An experimentally verified hybrid Cassie-Mayr electric arc modelfor power electronics simulations

This paper presents an electric arc model that can approximately represent both the static and dynamic characteristics of an arc load controlled by a power electronic circuit. The proposed model was developed from the combination and modifications of the classical Cassie and Mayr equations. The model equations have been expressed in a form suitable for incorporation into circuit simulators employing the nodal analysis method of equation solving. The model has been test-implemented in the Saber circuit simulator. Simulated and experimental results appear to be in good agreement     

IEEE standard 802.16: a technical overview of theWirelessMANTM air interface for broadband wirelessaccess

The broadband wireless access industry, which provides high-rate network connections to stationary sites, has matured to the point at which it now has a standard for second-generation wireless metropolitan area networks. The IEEE standard 802.16, with its WirelessMAN^TM air interface, sets the stage for widespread and effective deployments worldwide. This article overviews the technical medium access control and physical layer features of this new standard     

Adaptive predictive control algorithm based on Laguerre Functional Model

Laguerre Functional Model has many advantages such as good approximation capability for the variances of system time‐delay, order and other structural parameters, low computational complexity, and the facility of online parameter identification, etc., so this model is suitable for complex industrial process control. A series of successful applications have been gained in linear and non‐linear predictive control fields by the control algorithm based on Laguerre Functional Model, however, former researchers have not systemically brought forward the theoretical analyses of the stability, robustness, and steady‐state performance of this algorithm, which are the keys to guarantee the feasibility of the control algorithm fundamentally. Aimed at this problem, we introduce the principles of the Incremental Mode Linear Laguerre Predictive Control (IMLLPC) algorithm, and then systemically propose the theoretical analyses and proofs of the stability and robustness of the algorithm, in addition, we also put forward the steady‐state performance analysis. At last, the control performances of this algorithm on two different physical industrial plants are presented in detail, and a number of experimental results validate the feasibility and superiority of IMLLPC algorithm. Copyright © 2005 John Wiley & Sons, Ltd.     

钼的高灵敏显色反应及其应用

本文提出了钼的高灵敏显色反应[Mo（Ⅵ）－SCN－Morin－BPR－Twwen80体系]和在测定微量钼的应用。研究了Mo（Ⅵ）、SCN、桑色素（Morin）、溴邻苯三酚红（BPR）和吐温80（Tween80）显色配位体系的特性，该体系的最大吸收峰为565nm，最佳酸度为0．10～0．35mol／LH2SO4介质中，摩尔吸光系数ε＝3．5×106L·mol(-1)·cm(-1)，在565nm波长处空白值最低。配合物的组成比为Mo（Ⅵ）：SCN：Morin－BPR－1：6：3（在Tween80存在下）。0～2．50μgMo(6 )／50mL范围内，服从郎伯－比尔定律。回收率为98％～102％。应用此法测定土壤和头发中微量钼，获得满意的结果。     

等离子炉炭热法冶炼钼铁

等离子炉炭热法冶炼钼铁是利用炭在高温下的强还原性，以炭热和等离子热代替金属热．直接得到优质钼铁。     

STUDY ON RESIDUES OF ~（14）C－FENITROTHION IN MODEL RICE－FISH ECOSYSTEM AND FIELD RICE－FISH ECOSYSTEM

ＳＴＵＤＹＯＮＲＥＳＩＤＵＥＳＯＦ~（１４）Ｃ－ＦＥＮＩＴＲＯＴＨＩＯＮＩＮＭＯＤＥＬＲＩＣＥ－ＦＩＳＨＥＣＯＳＹＳＴＥＭＡＮＤＦＩＥＬＤＲＩＣＥ－ＦＩＳＨＥＣＯＳＹＳＴＥＭＺｈａｎｇＺｈｏｎｇｌｉａｎｇ（张仲良）；ＷａｎｇＨｕａｘｉｎ（王化新）；Ｇ?..     

用于重离子核反应实验测量的纵向电场气体电离室

本文报道了一种新型的大动态范围，多叠层探测器系统组件之一的纵向电场气体电离室的构造，性能和在中能得离子核反应实验中的应用。     

Protocol design and performance analysis for manufacturing messagespecification: A Petri net approach

The manufacturing message specification (MMS) is the ISO standard communication protocol specific to manufacturing. To analyze MMS design and performance, service unit automats are introduced to represent individual MMS services, while service connection Petri Nets (PNs) are constructed from these automats to describe MMS service connections and processes. This approach makes MMS protocol specification and analysis possible in terms of well-developed concepts and methods in PN theory. It leads to a distributed and hierarchical model of MMS software system by integrating service connection PNs. A generalized stochastic PN for MMS performance evaluation is obtained by incorporating service parameters and time factors into the model. A technique based on T-invariants is used to simplify the performance analysis     

钼酸铵生产中杂质的分离方法

简要地介绍了钼酸铵生产中有害杂质的各种分离方达及应用情况，并就各种方法的利弊作了对比说明。