An Object-Oriented Transaction Model

In object-oriented database systems(OOBSs),the traditional transaction models are no longer suitable because of the difference between the object-oriented data model(OODM)and the conventional data models(e.g.relational data model).In this paper,transction models for advanced database applications are reviewed and their shortcomings are analyzed.Exchangeability of operations is proposed instead of commuativity and recoverability for using more semantics in transaction management.As a result,an object-oriented transaction model(in short,OOTM)is presented.It is not modeled for some special application,but directly based on object-oriented paradigms.A transaction is regarded as an interpretation of a metho.Each transaction(even subtransactions)keeps relative ACID(Atomicity,Consistency,Isolation,Durability)properties,therefore the special problems appearing in OOBSs such as“long transactions”,“visibility of inconsistent database state”can be solved.     

捕收剂混合使用的协同效应与其浮选性能的相关关系研究

本文是关于捕收剂混含使用所产生的协同效应大小的相关因素和相关关系研究。研究结果表明,混用组合的协同效应大小与组合中各药浮选性能差之间存在相关关系,其浮选性能差以收率档次差与品位档次差的算术和表示,并命名为CS值。利用这一相关关系,可以大致预测新的混合用药组合的协同效应,从而为选择和设计新的药剂组合提供了一定的依据。     

BPEL中的事务处理机制

Web服务业务流程执行语言是一种流程定义语言,它使企业能够描述既能使用又能提供Web Services的复杂的业务流程。在研究了分布式事务处理的核心概念及其特点的基础上,详细分析了Web服务事务规范WS-COOR/WS-AT/WS-BA以及BPEL4WS中的事务处理机制,并举例进行了说明。     

Comparing alternative cellulosic biomass biorefining systems: Centralized versus distributed processing systems

This study explores how two different cellulosic ethanol production system configurations (distributed versus centralized processing) affect some aspects of the economic and environmental performance of cellulosic ethanol, measured as minimum ethanol selling price (MESP) and various environmental impact categories. The eco-efficiency indicator, which simultaneously accounts for economic and environmental features, is also calculated. The centralized configuration offers better economic performance for small-scale biorefineries, while the distributed configuration is economically superior for large-scale biorefineries. The MESP of the centralized configuration declines with increased biorefinery size up to a point and then rises due to the cost of trucking biomass to the biorefinery. In contrast, the MESP in the distributed configuration continuously declines with increasing biorefinery size due to the lower costs of railroad transportation and the greater economies of scale achieved at much larger biorefinery sizes, including biorefineries that reach the size of an average oil refinery—about 30,000 tons per day of feedstock. The centralized system yields lower environmental impacts for most impact categories than does the distributed system regardless of the biorefinery size. Eco-efficiency analysis shows that the centralized configuration is more sustainable for small-scale biorefineries, while the distributed configuration with railroad transport is more sustainable for large-scale biorefineries. Compared with gasoline from petroleum, cellulosic ethanol fuel offers sustainability advantages for the following environmental impact categories: fossil energy consumption, global warming, human health impacts by particulate matter, ozone layer depletion, ecotoxicity, human health cancer, and human health non-cancer, depending somewhat on the biorefinery sizes and the system configurations.     

分子印记聚合物压电模拟生物传感器测定烟草中的绿原酸

为快速准确测定烟草中的绿原酸,基于压电石英晶体传感器灵敏的响应性能,结合分子印记聚合物的特异识别性能,研制出绿原酸分子印记压电体声波模拟生物传感器,还探讨了膜的修饰作用,验证了该传感器的印记效应,优化了实验条件。该法线性范围为5.0×10-8～1.0×10-4mol/L,回收率为96.7%～105.0%,RSD为3.7%,并用该法测定了一些烟草中的绿原酸含量。     

Synergistic effects of formaldehyde and alcoholic extract of plant leaves for protection of N80 steel in 15%HCl

Abstract

The synergistic effects of formaldehyde and an alcoholic extract of plant leaves have been studied by weight loss measurements at temperatures up to 363 K using various concentration ratios of the two inhibitors to protect N80 steel against corrosion in 15% hydrochloric acid. The inhibition efficiency was found to decrease with increasing temperature for all except two of the various concentration ratios that were studied. After identifying these two most promising mixtures, their corrosion prevention effects for N80 steel in hydrochloric acid were studied in more detail by weight loss and potentiostatic polarisation measurements. The corrosion rate of the steel was decreased by the presence of small additions of the inhibitors. The extent of decrease was found to depend on the nature of the corrosion inhibitor and its concentration. The inhibition efficiencies of the two plant based inhibitor mixtures were compared with those of two commercially available oil industry corrosion inhibitors. In all cases the adsorption of the inhibitors on the steel appeared to follow the Frumkin or Langmuir adsorption isotherm. The inhibition efficiencies of the two plant based inhibitors and the two commercial inhibitors were evaluated at a concentration level of 0.8% for temperatures in the range 303 K to 363 K) and exposure times of between 1 h and 24 h. Thermodynamic parameters including the free energy of adsorption, activation energy, enthalpy and entropy were calculated in both the absence and presence of inhibitors. Potentiostatic polarisation tests have revealed that inhibitors are primarily of the anodic type.     

Chelant enhanced passivation of carbon steel in deoxygenated alkaline aqueous solutions

Abstract

The passivation characteristics of carbon steel surfaces at 473 K in the presence of certain chelating agents such as NTA DTP A, and HEDTA are described. The relative impacts of these chelants on the passivation process are evaluated by using base metal loss, soluble and insoluble iron concentrations in the mediums SEM studies of the topography of the surface coatings, and electrochemical investigations of the protection afforded by the oxide coating. The results have been compared with the passivation behaviour obtained under simple alkaline pH (LiOH) treatment (without chelating agents) and that previously obtained in the presence of EDTA. It is found that at 473 K, the presence of these complexing agents greatly increases the base metal loss, although a lower base metal loss is observed with LiOH. but the oxide film formed is more protective than the one formed under LiOR or EDTA treatments. The morphology of the coatings formed under complexing conditions has revealed highly developed crystallite faces on the outer surface layer. It is concluded that at 473 K passivation by LiOR is preferred to that given by the chelants.     

Acid rain: Its effects on lakes, streams and fish

Emissions of sulphur and nitrogen oxides from power stations make a major contribution to the acidification of surface waters with adverse consequences for fish and other aquatic life. The results of a recent six-year Anglo-Scandinavian research programme enable us to account quite well for the progressive acidification of surface waters in relation to topography, geology, soil type, climate and land use.     

MagneSil™ Paramagnetic Particles: Magnetics for DNA Purification

MagneSil™ Paramagnetic Particles are silica-paramagnetic particles with an affinity for nucleic acids under defined conditions. Particle structure and solution composition can be altered to selectively adsorb nucleic acids based upon type and size. These properties have been used to develop purification methods based on a three-step bind, wash, and elute process. The MagneSil™ technology is readily adaptable to robotic platforms, allowing complete automation of the purification process in either 96- or 384- well plate formats. This article introduces the basic physical and performance characteristics of the MagneSil™ Paramagnetic Particles.     

基于移动Agent的分布式事务模型研究

随着电子商务的发展,具有自主性、智能性特征的移动Agent逐渐成为该领域关注的一个热点。因为将移动Agent应用于电子商务领域必须保证移动Agent操作的原子性,所以就一定要用到事务服务,然而移动Agent规范中没有任何这方面的规定。通过分析C／S环境下解决分布式事务常用的技术——2PC协议,并将它与移动Agent环境相结合,提出了一种用于处理移动Agent事务的模型,经分析该模型性能和ACID特性良好。