Formation of thermally stable alkylidene layers on a catalytically active surface

Materials containing organic-inorganic interfaces usually display a combination of molecular and solid-state properties, which are of interest for applications ranging from chemical sensing to microelectronics and catalysis. Thiols--organic compounds carrying a SH group--are widely used to anchor organic layers to gold surfaces, because gold is catalytically sufficiently active to replace relatively weak S-H bonds with Au-S bonds, yet too inert to attack C-C and C-H bonds in the organic layer. But although several methods of functionalizing the surfaces of semiconductors, oxides and metals are known, it remains difficult to attach a wide range of more complex organic species. Organic layers could, in principle, be formed on the surfaces of metals that are capable of inserting into strong bonds, but such surfaces catalyse the decomposition of organic layers at temperatures above 400 to 600 K, through progressive C-H and C-C bond breaking. Here we report that cycloketones adsorbed on molybdenum carbide, a material known to catalyse a variety of hydrocarbon conversion reactions, transform into surface-bound alkylidenes stable to above 900 K. We expect that this chemistry can be used to create a wide range of exceptionally stable organic layers on molybdenum carbide.     

渗硼金刚石薄膜电极用于有机废水降解的实验

为了研究渗硼金刚石薄膜电极电化学性能以及用于含有机污染物的废水处理的可行性,采用循环电解的方法,对含苯酚的废水进行了电化学氧化实验,同时与活性涂层钛阳极进行了对比实验研究,考察了阴极的可替代性,最后用两种电极对含苯胺的工业废水进行了对比实验。实验结果表明,金刚石电极不仅具有优越的电化学性能和优异的电化学指标,而且可以用于电化学废水处理;同时,用钛电极代替金刚石作阴极经济可行。     

大学生科学素质和创新能力与无机化学实验教学

介绍了无机化学实验的重要性,在分析了无机化学实验的特点和教学中存在的一些问题后,针对性地提出了解决问题的方法。在无机化学实验教学中,首先要抓学生的基本操作和技能的训练,使其形成规范化的操作,并养成良好的实验习惯。探讨了在无机化学实验中培养学生的创新能力和树立绿色化学思想。通过改进实验内容、妥善处理实验产生的废弃物等方法,实现无机化学实验绿色化。     

Effects of the surface-adsorption of boron-doped diamond electrode on its electrochemical behavior

As a kind of new functional material, diamond has unique physical and chemical properties[1 - 3]. Its chemical stability is perfect because it hardly reacts with acids and alkalis. Researchers tried to apply dia- mond as electrochemical electrode to waste…     

中学化学教学语言的特点及其运用的要求

阐述了中学化学教学语言的特点:科学性、形象性、探索性、实践性,提出了中学化学教学中应遵循的5个要求:科学性与教育性相结合、形象性与抽象性相结合、探索性和求实性相结合、实践性与理论性相结合、重视化学语言.     

网络可靠度BDD分析中2种边排序策略的性能比较

网络可靠度二元决策图（BDD）分析过程包含边排序、BDD生成和可靠度评估3个步骤,其中BDD生成和可靠度评估的计算复杂度和BDD尺度线性相关,而BDD尺度取决于边排序．因此,边排序问题是研究网络可靠度BDD分析的核心．在实现广度优先和深度优先2种边排序策略的基础上,针对规则网络（N＊N型和M＊N型）,比较了这2种策略的分析性能．实验数据表明：1）规则网络中广度优先边排序策略优于深度优先边排序策略;2）当M〉N时,广度优先边排序策略在M＊N型网络中的性能表现优于与之等价的N＊M型网络．这些结论为设计更优的启发性边排序策略提供了重要依据．     

利用二元决策图求解故障树的基本事件排序

故障树分析是一种核电站常用的概率安全评价方法。对利用二元决策图求解故障树方法中的关键问题——基本事件排序进行了研究。先将故障树转化成二元决策图,然后通过遍历二元决策图直接获取割集。在转化的过程中,基本事件的排序对二元决策图的规模和计算速度有着直接的影响。寻找基本事件的最优排序是该方法的重点。该文提出的三条排序法则,对基本事件的排序有明显的帮助,可使二元决策图结点数减少约二分之一。     

无机化学实验教学的改革思考

文章在分析了无机化学实验的特点和教学中存在的一些问题后 ,指出在无机化学实验教学中 ,首先要抓学生的基本操作和技能的训练 ,使他们形成规范化的操作 ,并养成良好的实验习惯 ,才能使学生在今后的实验和工作中受益。     

CVD金刚石薄膜的掺硼研究

主要介绍硼掺杂金刚石膜的生长．采用热灯丝CVD法在硅上制备金刚石薄膜，采用三氧化二硼制备硼掺杂金刚石膜．利用拉曼光谱分析硼掺杂金刚石膜的生长情况．结果表明：硼的掺杂质量分数随生长时间延长而增大；利用SEM观察硼掺杂金刚石膜的表面晶粒变小；利用银浆在掺杂金刚石膜表面制备电极，测试电流随温度升高而变大.     

从专利分析看BDD电极的研究进展

掺硼金刚石电极在污废水处理领域具有广阔的应用前景。采用专利检索采集技术建立了该领域专利数据库,并对该数据库进行了统计分析,提出了提高我国专利技术研发应用应采取的措施。分析表明,国际上从1992年起逐步申请该领域专利,目前日本和美国在研发中处于领先地位,我国也已申请70余项专利,近些年在该领域专利申请量呈上升趋势,形成了研究BDD电极的热潮;国外主要由日本和美国开展这方面的工作,德国的CONDIAS公司不仅申请了大量专利,且其产品也已进入市场;国内主要是东南大学、同济大学等高校在做这方面的研发工作。     

基于递归BDD的网络系统可靠度算法

在网络系统可靠度的BDD算法中,将网络系统表示成BDD时二叉树中存在一定重复和冗余项,从而影响了不交化最小路集的搜索效率.为此,提出了一种基于递归BDD(RBDD)的网络系统可靠度算法.在该算法中,RBDD包括2个二叉树,一个是包含1个伪叶节点的二叉树,另一个是伪叶节点对应的二叉树.理论分析和实例都表明由RBDD得到的...     

Heck偶联反应在有机单分子膜上的应用

利用Heck偶联反应成功地改变了自组装单分子有机薄膜的化学结构以及末端基团,薄膜末端的碘苯基团与对卤苯乙烯在标准的Heck反应条件下成功发生了偶联反应.这些薄膜经过了接触角、膜厚以及X射线光电子能谱的详细表征.这种表面修饰的方法有效地改变有机薄膜的表面化学.     

环蕃分子及其衍生物非线性光学性质的理论研究

采用密度泛函理论计算方法研究了环蕃分子及其衍生物的非线性光学性质,探讨了将其作为非线性光学开关材料的可能性.计算结果表明:当不施加外电场时,该新型分子和设计的衍生物分子均为中心对称结构,其非线性光学响应性质中的第一超极化率为零,对应于分子开关中的"关"状态;而在恰当的外电场强度下,转变为非中心对称结构,并具有很大的第一...     

金刚石薄膜电极处理含氯酚废水的实验研究

以硼掺杂金刚石薄膜(BDD)为电极,采用电化学氧化的方法对含氯酚废水进行实验研究。采用循环流动的方式,结果表明:在给定不同恒电位的情况下,电流随时间变化的规律也不同;在高电位时电流密度比较大,使间接氧化增强,导致COD去除率和瞬时电流效率(ICE)增大;由于支持电解质N aC l在电解过程中产生的次氯酸盐氧化性强,因此N aC l比H2SO4对COD去除率和ICE增大更有利。采用钛基活性涂层(ACT)电极与金刚石电极的对比实验发现:由于BDD电极的弱吸附性,其处理效果明显优于ACT。     

有机化学教学实践谈

根据有机化学学科特点,通过调整教学内容、结构,引入疑问式教学法,采用多媒体技术进行教学,注重理论联系实际,达到提高教学质量、培养合格人才的教学目的。     

A New Method for the Detections of Multiple Faults Using Binary Decision Diagrams

With the complexity of integrated circuits is continually increasing, a local defect in circuits may cause multiple faults. The behavior of a digital circuit with a multiple fault may significantly differ from that of a single fault. A new method for the detection of multiple faults in digital circuits is presented in this paper, the method is based on binary decision diagram （BDD）. First of all, the BDDs for the normal circuit and faulty circuit are built respectively. Secondly, a test BDD is obtained by the XOR operation of the BDDs corresponds to normal circuit and faulty circuit. In the test BDD, each input assignment that leads to the leaf node labeled 1 is a test vector of multiple faults. Therefore, the test set of multiple faults is generated by searching for the type of input assignments in the test BDD. Experimental results on some digital circuits show the feasibility of the approach presented in this paper.     

Energy consumption of electrooxidation systems with boron-doped diamond electrodes in the pulse current mode

A pulse current technique was conducted in a boron-doped diamond (BDD) anode system for electrochemical wastewater treatment. Due to the strong generation and weak absorption of hydroxyl radicals on the diamond surface, the BDD electrode possesses a powerful capability of electrochemical oxidation of organic compounds, especially in the pulse current mode. The influences of pulse current parameters such as current density, pulse duty cycle, and frequency were investigated in terms of chemical oxygen demand (COD) removal, average current efficiency, and specific energy consumption. The results demonstrated that the relatively high COD removal and low specific energy consumption were obtained simultaneously only if the current density or pulse duty cycle was adjusted to a reasonable value. Increasing the frequency slightly enhanced the COD removal and average current efficiency. A pulse-BDD anode system showed a stronger energy saving ability than a constant-BDD anode system when the electrochemical oxidation of phenol of the two systems was compared. The results prove that the pulse current technique is more cost-effective and more suitable for a BDD anode system for real wastewater treatment. A kinetic analysis was presented to explain the above results.     

不同氧化程度的掺硼金刚石膜电极的电化学性能及电荷转移速率研究

通过阳极电化学氧化法, 制备不同氧化程度的掺硼金刚石膜(BDD)电极, 并对其进行表征。分别采用循环伏安法和 Mott-Schottky 曲线, 研究不同氧化程度的 BDD 电极的电化学性质和电荷转移速率。扫描电子显微镜和拉曼光谱分析表明, 氧化后的 BDD 电极形貌和晶型结构几乎未发生变化, 但 EDX 能谱分析发现BDD 表面氧含量明显增加。循环伏安法和 Mott-Schottky 曲线阳极电流法研究发现, 电荷转移速率随氧化程度的增大而逐渐增大。接触角实验进一步证实, 随着 BDD 电极氧化程度的增加, 接触角减小, 电极表面亲水性逐渐增大, 因此以阳极电流方式表示的电荷转移速率增大。然而, Mott-Schottky 曲线以氧化还原电位差方式表示的电荷转移速率随氧化程度的增大, 先增大, 后减小, 这是由于在不同的氧化时间下, 表面基团的种类及其各成分在总含氧量中所占比例不同, 因此产生的电荷转移速率也不相同。     

保细节的基于曲面控制的网格变形

综合考虑微分域网格编辑方法在细节特征保持方面的优势以及细分曲面的任意拓扑适应性,提出一种基于曲面控制的网格变形方法.以流形网格上的离散泊松方程为理论基础,在指定变形区域模型表面设计细分曲面作为变形控制曲面,并将对它的编辑操作映射为对变形区域网格的梯度场操纵,最后通过泊松重建得到变形后的网格模型.文中变形方法克服了传统参数样条曲面难以贴合任意拓扑物体外形的缺陷,可以有效保持物体的细节特征.     

Efficient Fault Tree Analysis of Complex Fault Tolerant Multiple-Phased Systems

Fault tolerant multiple phased systems (FTMPS), i.e., systems whose critical components are independently replicated and whose operational life can be partitioned in a set of disjoint periods, are called "phases". Because of their deployment in critical applications, their reliability analysis is a task of primary relevance to validate the designs. Fault tree analysis based on binary decision diagram (BDD) is one of the most commonly used techniques for FTMPS reliability analysis. To utilize the technique the fault tree structure of FTMPS needs to be converted into the corresponding BDD format. Our research work shows that the system BDD generation algorithms presented in the literature are too inefficient to be used for industrial complex FTPMS because of the problems, such as variable ordering and combination of large BDDs. This paper presents a more efficient approach consisting of a flatting pre-processing technique, a proved efficient ordering heuristic and a bottom-up generation algorithm. The approach tries to combine share-variable BDDs by complex combination operation firstly and then combine no-share-variable BDDs using simple combination operation, thus to alvoid the intensive computations caused by large BDD combination operations. An example FTMPS is analyzed to illustrate the advantages of our approach.