氧化还原平衡智能处理系统(OREICS)的开发

以Visual Basic为工具,结合数据库技术,开发了氧化还原平衡智能处理系统(OREICS)。该软件针对氧化还原平衡涉及的有关问题,提供了标准电极电势查询、电极电势计算、氧化剂／还原剂强弱判断、电池反应方向判断、计算反应平衡常数,以及元素电势图的自动生成和歧化反应判断等功能。软件界面友好,使用方便,可作为处理氧化还原平衡问题的强有力的工具。     

分子筛合成过程中三聚铝硅酸盐生成机理的DFT研究

采用密度泛函理论研究了在分子筛合成的碱性环境中铝硅酸盐三聚体的生成机理.在B3LYP/6-31 G(d,p)计算水平上对反应物、过渡态和产物分别进行了几何结构的全优化和频率计算,通过内禀反应坐标的方法验证了反应路径,并计算了反应的活化能.采用COSMO-RS模型考虑了溶剂效应.结果表明,二聚硅酸分子SiOSi(OH)6和单体铝酸根离子Al(OH)**的缩聚反应可以按照协同方式进行,SiO-Al桥键的形成与水分子的脱除同时发生,最终生成铝硅酸盐的三聚体.计算得到的缩聚反应活化能为80.1 kJ/mol.     

氧化型铜锌超氧化物歧化酶的量化计算及与还原型Cu(Ⅰ)Zn-SOD的计算比较

运用G94程序,利用密度泛函方法下的LANL2DZ基组,对于氧化型Cu(Ⅱ)Zn-SOD活性中心进行了从头计算,并与还原型的Cu(Ⅱ)Zn-SOD的计算在轨道能量、前线轨道贡献等方面进行了比较。结果表明:Cu(Ⅱ)易于接受O_2~-自由基不成对电子参与反应,是O_2~-的接受体,从量化计算角度证实了酶的催化活性机理是通过Cu(Ⅱ)→C(I) 的交替氧化还原而完成的,同时起到清除O_2~-的功效。     

PAAm􀀁g􀀁CB/Al2O3 凝胶杂合材料的制备及 负蒸气系数效应研究

利用自由基反应机理,以过氧化苯甲酰(BPO)为引发剂,在炭黑表面引入-CH2OH或-C(CH3)2OH;然后再以硝酸铈铵/CB-CH2OH或硝酸铈铵/CB-C(CH3)2OH 组成氧化还原引发体系,在CB表面接枝上聚丙烯酰胺(PAAm-g-CB);在PAAm-g-CB 存在下,进行AIP(异丙醇铝)的溶胶-凝胶化反应,制得了一种新颖的具有智能响应性的PAAm-g-CB/Al2O3凝胶杂合材料.研究了其气敏性能和湿敏性能.结果发现,该杂合材料在其良溶剂蒸气中电阻急剧下降,呈现负蒸气系数现象(NVC);而在不良溶剂蒸气中电阻几乎不发生变化.其响应性能与杂合体间氢键作用密切相关,并受接枝率大小的影响;结合IR、DTA、TGA等分析方法推断了杂合材料分子结构模型.     

L-半胱氨尾式卟啉铜(Ⅱ)自组装修饰金电极制备及对地表水中苯酚的检测

将制备的L-半胱氨卟啉铜(Ⅱ)(CuL)配合物自组装在Au电极表面,获得电化学苯酚传感器(CuL/Au CME).在pH7.0的磷酸盐缓冲液中于-0.4～0.5V(vs.SCE)电位范围内有一对氧化还原峰,其峰电位分别为氧化峰电位Epa=90mV,还原峰电位Epc=-60mV.实验表明该电极上,苯酚可被CuL催化氧化,通过产物在电位0.1 V下的电化学响应对苯酚进行测定,测定过程不需要再向体系中添加媒介体.该电极对苯酚表现出快速的响应(响应时间＜10s).传感器对苯酚的测定具有较宽的线性范围(5×10-7～2.5×10-4 mol/l),检出限为2.0×10-7mol/l.测定了电极稳定性,将该电极用于地表水中苯酚含量检测,并与标准4-氨基安替比林分光光度法作了对照,结果满意.     

密度泛函方法的ZSM-5分子筛上苯与乙烯烷基化反应机理研究

采用密度泛函(DFT)方法对于ZSM-5分子筛上苯与乙烯的烷基化反应机理进行研究。选取了包含酸性质子的8T原子簇模型代表ZSM-5分子筛的部分结构。采用B3LYP/6-31G(d)水平从生成能与反应活化能角度对于烷基化反应发生时可能存在的2种联合机理和一种分步机理进行了计算与比较。结果表明,联合反应机理中乙烯的质子化和C-C键的形成同时发生,而分步机理开始于乙醇盐中间体的生成,随后与苯反应生成反应产物。分步机理中乙醇盐中间体生成步骤的活化能(124.55 kJ/mol)低于联合机理的反应活化能(168.98 kJ/mol和156.06 kJ/mol),而烷基化步骤的活化能(209.35 kJ/mol)高于联合机理的反应活化能,由此可以推断ZSM-5分子筛上苯与乙烯的烷基化反应时2种机理同时发生,存在竞争关系。     

邻苯三酚自氧化机理的量子化学研究

以WINMOPAC7.21和MOPAC2012中提供的PM6半经验量子化学方法研究了邻苯三酚自氧化机理。PM6半经验量子化学方法首先对邻苯三酚自氧化过程相关的各分子进行构型优化,利用提供的热力学参数计算获得了的热力学参数,包括分子的生成热,分子的熵,从而计算出每步反应的吉布斯自由能的变化值,进行反应自发性评价,揭示自氧化反应发生的可能性。由各相关分子的最高占有轨道,和最低空轨道能量的分析,获得了分子的第一电离势等与电子相关的分子指数,研究了邻苯三酚自氧化过程的机理,为文献推测的机理提供了量子化学的支撑。     

高温超导体的电化学研究

目前,高温超导体的研究工作方兴未艾,在过去的几年里,人们已成功地发现了一些高温超导材料,如 YBa_2Cu_3O_7(Tc=93K)、Tl_2Ba_2Ca_2Cu_3O_(10)(Tc=125K)、Bi_2Sr_2CaCu_2O_8(Tc=85K)等。现在人们以极大兴趣通过改变化学组分来直接增加超导温度 Tc,制备稳定的单晶超导薄膜。由于超导临界温度的不断提高,许多科学工作者正满怀希望地研究和估价超导材料实际应用的可能性。虽然超导电性机理还不为人们所了解,超导现象也只在液氮温度下出现,但超导材料的存在,对许多科学领域都具有重要的理论意义和现实意义因此,超导材料的表面稳定性、老化效应以及可能的相界面反应,如腐蚀、金属沉积、氧化还原过程、光电化学等,都在引起人们的注意。     

核黄素在碳纳米管修饰电极上的电化学行为

制成了碳纳米管(CNT)和碳纳米管复合β-环糊精(p-CD)修饰电极,用循环伏安(CV)和差分脉冲伏安法(DPV)对核黄素(RF)的电化学行为进行了研究.实现了核黄素在不同pH的溶液中的氧化还原机理的探讨及其定量测定,线性范围5.0×10-7～2.5×10-6mol/L,相关系数r=0.998 5,检测限为3.0×10-7mol/L.实验表明碳纳米管对核黄素的氧化还原有电催化作用,主要是由于碳纳米管的一维管状结构及独特的电子特性促进了电子的传递.β-CD的加入对RF电位没有影响,但增大了峰电流,可能是因为环糊精复合碳纳米管修饰电极的界面体现了新颖的建筑层-碳纳米管集合体大的孔隙充填小孔的环糊精,发挥了碳纳米管和环糊精的双重功能.     

羧基与钙离子吸附机理的密度泛函的仿真研究

运用CASTEP模块对柠檬酸吸附于石膏晶体表面的空间结构、电子结构、络合吸附机理进行了理论探索,基于密度泛函理论的第一性原理优化了Ca SO4(010)晶面结构,计算了晶面与柠檬酸反应吸附能。通过对柠檬酸吸附方式的假设和计算,发现最佳吸附方式为柠檬酸羧基结构中的H原子被晶面(010)上的钙原子的垂直吸附。吸附机理主要表现为柠檬酸中羧基的H原子1s轨道中的电子向晶体表面(010)上Ca原子的3d轨道发生了转移,从而形成杂化轨道。     

The use of ignition delay time in genetic algorithms optimisation of chemical kinetics reaction mechanisms

This study presents the use of a genetic algorithm to optimise new chemical kinetic reaction mechanisms using ignition delay time measurements. It is well recognised that many important combustion phenomena are kinetically controlled. Therefore it is important to determine accurately the reaction rate parameters associated with a given reaction mechanism. The genetic algorithm employed, uses perfectly stirred reactor, laminar premixed flame and ignition delay time data in the inversion process in order to produce efficient reaction mechanisms valid for a wide range of combustion processes and various operating conditions.     

On the Natural Selection of Market Choice

An evolutionary approach to the problem of economic mechanism choice is presented. It demonstrates the power that a single participant has on the choice of a preferred market mechanism. A population of sellers, each with one of two possible economic mechanisms, facing potential buyers, is presented as a test model. It is shown that if two auctions, such as first- and second-price auctions, are to attract an identical number of buyers, although under the model assumptions their expected revenues are identical, sellers using a first-price auction mechanism will be selected for. However, if a second-price auction attracts one additional buyer, then it will be selected for by the evolutionary process. These results are extended to the choice between an arbitrary k- and l-price auctions.     

DESIGN OF AN ITERATIVE MULTI-ITEM DOUBLE-AUCTION MECHANISM

There have been many multi-item auction mechanisms. As it is not allowed for both sellers and buyers to submit bids and offers in nearly all existing multi-item auction mechanisms, the impartial profit distribution for both sellers and buyers cannot be realized in those mechanisms. Although it is possible for both sellers and buyers to submit bids and offers in a combinatorial exchange, the impartial profit distribution for all individual participants cannot be realized due to its pricing mechanism that focuses only on enforcing budget balance. This paper proposes an iterative multi-item unit-demand and unit-supply double-auction mechanism with a new winner determination and pricing mechanism for distributing profit impartially from the viewpoints of individual participants regardless of whether they are buyers or sellers. It also analyzes the theoretical features of the proposed auction mechanism, including those related to its strategic behavior and efficiency.     

Visual Prolog截断机制对回溯的作用机理

回溯是一种获得目标所有可能解的良好方法.然而不恰当地使用回溯,可能导致系统效率降低,时空开销增大,因此必须设置相应机制,仔细控制回溯过程.Visual Prolog的控制谓词,即失败谓词fail和否定谓词not,与截断机制,包括静态截断机制和动态截断机制,构成了完整的目标搜索求解控制机制,可以实现对搜索过程的仔细控制,减少不必要的回溯.该文在考察Visual Prolog回溯机制和截断机制的基础上,通过实例,对其静态截断机制和动态截断机制进行了详细分析,从而揭示回溯机制和截断机制的本质特性和应用机理.     

Using haptic feedback as an aid in the design of passive mechanisms

This paper presents a novel investigation of the effectiveness of haptic feedback for designing a class of interconnected multi-body systems such as passive mechanisms. The traditional application of haptic feedback in the design process has been in applications such as parts assembly or mold design. The design of the mechanism discussed in this paper is for applications where the user needs to manipulate the mechanism in order to interact with an environment. The objective of the design is to have the link ratios so that it can allow the user better movement control of the mechanism and thus give a better force amplification when there is a sudden change in the contact reaction force with the application environment. A haptic device is used as a design interface between the designer of such mechanisms and the virtual mechanism model. For this preliminary investigation, we used a four-bar mechanism. In our case study, we choose, as an example, to use the net distance travel of a tool when penetrating inside a model of a deformable surface as the design objective to minimize. The effects on the variation of this distance travelled can then be studied by adjusting some of the key design parameters used in the mechanism. To evaluate our proposed haptic-aided design environment, an informal preliminary user study was conducted, where each subject explored a sampled design space of the mechanism. The results of the user study suggest that the usage of a haptic device in the design of this class of mechanism can expedite the design process.     

Fair and resilient Incentive Tree mechanisms

We study Incentive Trees for motivating the participation of people in crowdsourcing or human tasking systems. In an Incentive Tree, each participant is rewarded for contributing to the system, as well as for soliciting new participants into the system, who then themselves contribute to it and/or themselves solicit new participants. An Incentive Tree mechanism is an algorithm that determines how much reward each individual participant receives based on all the participants’ contributions, as well as the structure of the solicitation tree. The sum of rewards paid by the mechanism to all participants is linear in the sum of their total contribution. In this paper, we investigate the possibilities and limitations of Incentive Trees via an axiomatic approach by defining a set of desirable properties that an Incentive Tree mechanism should satisfy. We give a mutual incompatibility result showing that there is no Incentive Tree mechanism that simultaneously achieves all the properties. We then present two novel families of Incentive Tree mechanisms. The first family of mechanisms achieves all desirable properties, except that it fails to protect against a certain strong form of multi-identity attack; the second set of mechanisms achieves all properties, including the strong multi-identity protection, but fails to give participants the opportunity to achieve unbounded reward. Given the above impossibility result, these two mechanisms are effectively the best we can hope for. Finally, our model and results generalize recent studies on multi-level marketing mechanisms.     

Indistinguishability and identifiability of kinetic models for the MurC reaction in peptidoglycan biosynthesis

An important question in Systems Biology is the design of experiments that enable discrimination between two (or more) competing chemical pathway models or biological mechanisms. In this paper analysis is performed between two different models describing the kinetic mechanism of a three-substrate three-product reaction, namely the MurC reaction in the cytoplasmic phase of peptidoglycan biosynthesis. One model involves ordered substrate binding and ordered release of the three products; the competing model also assumes ordered substrate binding, but with fast release of the three products. The two versions are shown to be distinguishable; however, if standard quasi-steady-state assumptions are made distinguishability cannot be determined. Once model structure uniqueness is ensured the experimenter must determine if it is possible to successfully recover rate constant values given the experiment observations, a process known as structural identifiability. Structural identifiability analysis is carried out for both models to determine which of the unknown reaction parameters can be determined uniquely, or otherwise, from the ideal system outputs. This structural analysis forms an integrated step towards the modelling of the full pathway of the cytoplasmic phase of peptidoglycan biosynthesis.     

Mechanistic insights into the catalytic reaction of plant allene oxide synthase (pAOS) via QM and QM/MM calculations

QM cluster and QM/MM protein models have been employed to understand aspects of the reaction mechanism of plant allene oxide synthase (pAOS). In this study we have investigated two reaction mechanisms for pAOS. The standard pAOS mechanism was contrasted with an alternative involving an additional active site molecule which has been shown to facilitate proton coupled electron transfer (PCET) in related systems. Firstly, we found that the results from QM/MM protein model are comparable with those from the QM cluster model, presumably due to the large active site used. Furthermore, the results from the QM cluster model show that the Fe^III and Fe^IV pathways for the standard mechanism have similar energetic and structural properties, indicating that the reaction mechanism may well proceed via both pathways. However, while the PCET process is facilitated by an additional active site bound water in other related families, in pAOS it is not, suggesting this type of process is not general to all closely related family members.     

An integrated security-aware job scheduling strategy for large-scale computational grids

All existing fault-tolerance job scheduling algorithms for computational grids were proposed under the assumption that all sites apply the same fault-tolerance strategy. They all ignored that each grid site may have its own fault-tolerance strategy because each site is itself an autonomous domain. In fact, it is very common that there are multiple fault-tolerance strategies adopted at the same time in a large-scale computational grid. Various fault-tolerance strategies may have different hardware and software requirements. For instance, if a grid site employs the job checkpointing mechanism, each computation node must have the following ability. Periodically, the computational node transmits the transient state of the job execution to the server. If a job fails, it will migrate to another computational node and resume from the last stored checkpoint. Therefore, in this paper we propose a genetic algorithm for job scheduling to address the heterogeneity of fault-tolerance mechanisms problem in a computational grid. We assume that the system supports four kinds fault-tolerance mechanisms, including the job retry, the job migration without checkpointing, the job migration with checkpointing, and the job replication mechanisms. Because each fault-tolerance mechanism has different requirements for gene encoding, we also propose a new chromosome encoding approach to integrate the four kinds of mechanisms in a chromosome. The risk nature of the grid environment is also taken into account in the algorithm. The risk relationship between jobs and nodes are defined by the security demand and the trust level. Simulation results show that our algorithm has shorter makespan and more excellent efficiencies on improving the job failure rate than the Min–Min and sufferage algorithms.