玻璃碳电极的激光改性处理

玻璃碳电极（ＧＣＥ）用激光脉冲照射处理后，电化学反应行为发生很大变化。背景电流减小，Ｆｅ３＋／Ｆｅ２＋氧化还原电对的电极反应速率显著提高，抗坏血酸（ＡＡ）在电极上呈现明显的吸附作用。     

A multi-agent decision support system for stock trading

A distributed problem solving system can be characterized as a group of individual cooperating agents running to solve common problems. As dynamic application domains continue to grow in scale and complexity, it becomes more difficult to control the purposeful behavior of agents, especially when unexpected events may occur. This article presents an information and knowledge exchange framework to support distributed problem solving. From the application viewpoint the article concentrates on the stock trading domain; however, many presented solutions can be extended to other dynamic domains. It addresses two important issues: how individual agents should be interconnected so that their resources are efficiently used and their goals accomplished effectively; and how information and knowledge transfer should take place among the agents to allow them to respond successfully to user requests and unexpected external situations. The article introduces an architecture, the MASST system architecture, which supports dynamic information and knowledge exchange among the cooperating agents. The architecture uses a dynamic blackboard as an interagent communication paradigm to facilitate factual data, business rule, and command exchange between cooperating MASST agents. The critical components of the MASST architecture have been implemented and tested in the stock trading domain, and have proven to be a viable solution for distributed problem solving based on cooperating agents     

A novel cyclic process using CaSO<Subscript>4</Subscript>/CaS pellets for converting sulfur dioxide to elemental sulfur without generating secondary pollutants: Part I. Feasibility and kinetics of the reduction of sulfur dioxide with calcium-sulfide pellets

Certain new sulfide-smelting processes and coal-gasification processes generate high-strength sulfur dioxide streams, for which a new process for converting sulfur dioxide to elemental sulfur needs to be developed because no process exists that is generally and economically applicable to the treatment of such streams. A thermodynamic and experimental investigation to develop a new process for converting sulfur dioxide to elemental sulfur by a cyclic process involving calcium sulfide and calcium sulfate without generating secondary pollutants was carried out. In this process, the starting raw material, calcium sulfate, is reduced by a suitable reducing agent, such as hydrogen, to produce calcium sulfide, which is used to reduce sulfur dioxide to elemental sulfur vapor and calcium sulfate. The latter is, in turn, reduced to regenerate calcium sulfide. In this Part I, detailed experimental results are presented on the kinetics of the reaction between sulfur dioxide and calcium-sulfide pellets, which produces elemental sulfur and calcium sulfate. The experiments were carried out at temperatures between 1023 and 1088 K and sulfur-dioxide partial pressures between 9 and 60 kPa by the use of a thermogravimetric analysis (TGA) technique. The rate of this reaction was demonstrated by the conversion of 40 pct calcium-sulfide pellets obtained from the hydrogen reduction of fresh calcium sulfate in 10 minutes at 1073 K under a sulfur-dioxide partial pressure of 43 kPa. The reactivity decreased somewhat during the first three cycles but remained largely unchanged thereafter up to the tenth cycle. This characteristic of the pellets is important because the solids must be reusable for repeated cycles to avoid generating secondary pollutants. A pore-blocking model was found to fit the reaction rate. The reaction is first order with respect to sulfur-dioxide partial pressure and has an activation energy of 101 to 134 kJ/mol (24 to 32 kcal/mol) for calcium-sulfide pellets reacted and regenerated several different times. Sulfur dioxide-containing streams from certain sources, such as the regenerator off-gas from an integrated-gasification, combined-cycle, desulfurization unit and new sulfide-smelting plants, contain much higher partial pressures of SO₂. In these cases, the rate of the first reaction is expected to be proportionally higher than in the test conditions reported in this article. The reduction kinetics of calcium-sulfate pellets with hydrogen gas is reported in the accompanying Part II.     

Microbiological denitrification of red beet juice

The purpose of study was the determination of optimal conditions for red beet juice denitrification by Paracoccus denitrificans bacteria as well as the evaluation of the usefulness of microbiologically treated juice for the production of a natural colouring preparation for foods. Total reduction of nitrates was found during bacterial culturing at 25 and 30 °C, at an initial pH of 7.0-8.0 and juice osmotic pressure of 900-1100 mOsm/kg. Microbiological denitrification procedure affected colour, taste and aroma of the juice. However, the use of juice as food colouring and component was made feasible by acidification and partial evaporation of water together with volatile substances.     

两种波长激光血管内照射生物效应比较

目的：研究同等照射条件的低强度532nm与633nm激光血管内照射生物效应的特点。方法：用532nm和633nm激光对健康大耳白家兔血管内照射，平均照射功率均设定在5mW左右，照射总能量约12J。两组家兔均于照前及照后1d、4d、7d、11d采集外周血，检测血浆ET、NO、MDA含量和SOD活性。结果：两组家兔上述各指标随照后时间的变化规律相似，经方差分析组间各指标都没有显著性差异。结论：同等照射条件下，低强度532nm与633nm激光照射血液的生物效应相似。     

氦氖激光对人胚腱细胞生长分泌的影响

目的 阐明氦氖激光促进人胚腱细胞增殖及分泌胶原的机制。方法 将传代培养的人胚腱细胞分为对照组、照射1日组、照射3日组及照射5日组。在氦氖激光照射的不同时相点，分别测定细胞DNA含量，cAMP水平及胶原分泌量。结果 在氦氖激光作用早期（1－3日），细胞cAMP水平与DNA合成均呈明显升高（P＜0.05)，细胞内信使物质合成及细胞增殖加快，但胶原分泌无变化，而在氦氖激光作用晚期（3－5日），当cAMP水平及DNA合成都不再改变时，腱细胞分泌胶原量显著增加（P＜0.01)。结论 氦氖激光可能通过作用于cAMP蛋白激酶A信号转导系统，从而调控人胚腱细胞增殖及胶原分泌。提示临床应用氛氖激光促进肌腱愈合宜从早期开始，并且需要照射足够长的时间。     

Suspension force and mechanism of debris flows

The paper discusses the postulated suspension force, by which it is possible to explain some enigmatic phenomena observed in different types of mass movements. This force is generated in thick suspensions as a result of friction between sinking solid particles and static water. The suspension force is related to the seepage force but they have opposite directions. Both forces form flow networks. Having explained the suspension force, the paper describes how this influences the movement of material, particularly in debris flows. Enigmatic features and the mechanism of debris flows and lahars are explained by virtue of the suspension force. Electronic Publication     

Scheduling railway traffic at a construction site

We consider the problem of rescheduling trains in the case where one track of a railway section consisting of two tracks in opposing directions is closed due to construction activities. After presenting an appropriate model for this situation we derive a polynomial algorithm for the subproblem of finding an optimal schedule with minimal latenesss if the subsequences of trains for both directions outside the construction site are fixed. Based on this algorithm we propose a local search procedure for the general problem of finding good schedules and report test results for some real world instances. Received: December 8, 1999 / Accepted: May 2, 2001