Active Layer of an Oxygen Electrode Based on Nanocomposite Disperse Carbon Carrier + Laccase Material

Effect of the carbon material dispersivity on the efficiency of oxygen electroreduction by laccase immobilized on finely divided colloidal graphite (FCG) and carbon black AD-100 is studied. A highly active composite material based on FCG with laccase immobilized on it is proposed and investigated. This creates optimum conditions for direct bioelectrocatalysis by enzyme molecules. The specific oxygen reduction current calculated per enzyme molecule for nanocomposite FCG + laccase is five times that on an AD-100-based composite. Increasing the active-layer thickness, which is of importance for creating a gas-diffusion oxygen electrode, reduces specific activity of composite and only the activity of ultrathin layers is thickness-independent. This is explained by percolation restrictions on the electron transport, which reduce the number of catalytically active centers in the electrode's active layer that take part in reaction. The FCG particles are presumed to form agglomerates in the active layer. The size of the agglomerates is determined on the basis of computer-aided modeling of percolation processes and experimental data on the dependence of the specific capacitance of the active mass on the active-layer thickness. Hypotheses on the origin of percolation phenomena are put forth. One such hypothesis is that agglomerates of carbon particles are fractal clusters.     

两种不同银源的光敏热成像材料感光性能对比

本文考察了以苯并三氮唑银为银源与以硬脂酸银为银源的水基型PTG材料感光性能的差异,采用了原位法和异位法两种方法来制备不同的PTG材料,并采用了加热显影与湿法显影两种方法显影,结果显示以AgBTA为银源的PTG材料的感光度都比以AgSt为银源的PTG材料的感光度高.通过对乳液pH值和pAg值以及Dember光电压的测定,发现显影过程中以AgSt为银源的PTG材料显影程度要比以AgBTA为银源的PTG材料显影程度高,潜影形成过程中AgBTA体系的潜影形成效率比AgSt体系的潜影形成效率高,导致最终实验结果是以AgBTA为银源的PTG材料的感光度比以AgSt为银源的PTG材料的感光度高.     

噻吩在Au_(13)和Pt_(13)团簇上加氢脱硫的反应机理比较

采用密度泛函理论研究了噻吩在立方正八面体的M_(13)(M=Au、Pt)团簇上的吸附和加氢脱硫行为。结果表明,噻吩以环吸附于Au_(13)上的Hol-tri位或Pt_(13)上的Hol-quadr位时最稳定,且Pt_(13)上的吸附稳定性更高。在M_(13)催化体系中,按间接加氢脱硫机理,反应可能依顺式加氢的方式进行;其中,C-S键断裂开环所需的活化能最高,是反应的限速步骤;按直接加氢脱硫机理,HS加氢所需活化能最高,是反应的限速步骤。同时该机理总体所需活化能较间接加氢脱硫机理更低,是更为合理的脱硫机理。噻吩加氢脱硫过程中,Au_(13)体系为放热反应,而Pt_(13)体系为吸热反应,并且Au_(13)体系加氢所需活化能更低;因此,Au_(13)更有利于噻吩加氢脱硫反应的进行。     

丙烯、氧气和环氧丙烷在Cu-NaCl/SiO2催化剂上吸附的红外光谱研究

 用红外光谱法研究了丙烯、丙烯/氧气混合气以及环氧丙烷(PO)在Cu-NaCl/SiO2催化剂上的吸附. 结果表明,丙烯在载体和催化剂上的吸附是完全可逆的. 丙烯和氧气在催化剂上共吸附后生成了丙烯醛,未观察到环氧丙烷(PO)生成. PO在载体和未还原催化剂上的吸附行为表明,PO与载体的硅羟基有强相互作用,PO发生开环反应生成开环物种. 而PO在还原态催化剂上的吸附行为较复杂,可能生成了酮类化合物.     

镧对红壤硝化、磷转化和酚分解作用的影响

通过室内培养和盆栽试验研究了La对红壤硝化作用,磷转化作用和酚分解作用的影响,低浓度下,La对土壤的硝化作用和磷转化作用均有某些刺激作用,但随着浓度的升高产生抑制作用并不断增加,La对土壤酚分解作用表现为剧烈的抑制作用,并随着浓度的升高,抑制作用不断增强,随着培养时间的延长,La对土壤硝化作用和酚分解作用的抑制作用有降低的趋势。     

木质素系和萘系分散剂在煤水界面的吸附性能

研究了两种木质素类分散剂SL(木质素磺酸钠)和MSSL(改性磺化碱木质素钠盐)和一种萘系分散剂(FDN)在大同煤表面的吸附量和动力学, 结果表明, SL和MSSL在煤表面的吸附量远比FDN的大, 但是拟合所得的Langmuir平衡常数K和吸附速率常数ka都比FDN的小, 这表明SL和MSSL在煤表面的吸附能力比FDN略差, 吸附速率较慢. 采用IR和XPS研究了煤表面分散剂吸附层的结果表明, 吸附了SL和MSSL的煤表面具有明显的“红移”现象, 并且SL和MSSL在煤表面的吸附层厚度分别为7.22和4.61 nm, 而FDN的吸附层厚度较小, 为2.11 nm. 分析认为, SL和MSSL在煤表面的吸附以氢键力为主, 吸附量较大, 吸附层较厚, 在煤表面呈多点式吸附; FDN主要以π电子极化吸附在煤表面呈卧式吸附, 吸附强度较大, 吸附层较薄.     

A study on feasibility of insect—control with γ-ray

Insect-control with Co-γ-ray is a method for conserving archives, books, cotton textiles, historical relics, wood structured houses and furniture, which are called irradiated objects later on. The temporary and residual effects of γ-ray on irradiated objects and the biological effects on insects are presented in this report.

Our study shows that there is no obvious harmful effect on irradiated objects when the ray is below 870 Gy, while there is obvious deterioration on the objects when the ray is above 870 Gy. On the other hand, the ray below 870 Gy is strong enough for the insects. In fact, at the dose of 43.5–130.5 Gy, the irradiated insects could be damaged on reproductive function, even sterilized, or killed.     

锰欠电位沉积的密度泛函计算与循环伏安实验的研究

用密度泛函计算和循环伏安法研究了锰在金和铅表面的欠电位沉积(UPD)行为. 理论计算, 假设生成紧密的二维相(2D)欠电位沉积层, 用基于密度泛函理论的DMol3软件计算在金与铅表面生成2D相锰层的欠电位偏移值∆fE2DMe, 证明锰在金表面可发生欠电位沉积, 而在铅表面不能发生欠电位沉积. 循环伏安实验结果与理论计算不一致: 金电极析氢电位高不利于研究锰的还原沉积反应, 没有发现锰的欠电位沉积现象; 铅电极在MnCl2溶液中有锰的欠电位沉积现象. 这种理论计算与电化学实验结果的差异, 主要是因为理论计算没有考虑溶剂与阴离子特性吸附作用的影响, 理论计算模型是电化学实验体系的一种理想模型.     

Intrinsic barrier for protonation of radical anions

Ab initio calculations on radical anions show that, counterintuitively, protonation on the radicaloid carbon is favored. In the case of radical anions derived from acrylonitrile and acrylaldehyde, protonation on the heteroatom is less favored than protonation on the radicaloid carbon. However, in nitroethylene, the preferred protonation site is on the nitro oxygen in accordance with experimental observation.     

Pt/HM,Pd/HM催化剂上NO-TPSR和CO-NO反应

消除NO对大气的污染，人们进行了广泛的研究，其中选择性催化还原是常用的方法[1]．众所周知，分子筛是常用的NO选择性还原催化剂载体，熊金保等[2]考察了Cu-ZSM-5催化剂表面NO的程脱产物，认为NO只吸附在Cu上，载体ZSM-5不吸附NO，Alvarez等[3]认为Na－ZSM-5和NaY表面有少量吸     

Activity of an enzyme immobilized on polyelectrolyte multilayers

The immobilization of α-chymotrypsin on the surface of boron silicate glass microspheres is conducted via the technique of multilayer adsorption of polyelectrolytes. It is shown that the enzyme is adsorbed on both positively and negatively charged surfaces and its activity is partially preserved relative to that in solution. The activity of the enzyme depends on the number of polyectrolyte layers preliminarily adsorbed on glass microspheres and on the charge of the surface. The activity of α-chymotrypsin adsorbed on the negatively charged surface is four times higher than the activity of this enzyme adsorbed on a positively charged surface.     

On the terms mass and weight

A short survey is given on mass units and recommendations on the proper use of the notations mass and weight.Whereas mass is an inertial physical quantity in classical mechanics, weight is a force due to the gravitational field and depending on the geographic situation.     

基于共轭高分子纳米复合材料发光二极管的研究进展

简要介绍了发光二极管 (LED)的发展历程和发光机理 ,着重论述了共轭聚合物纳米复合材料在LED发光层上的应用 ,讨论了基于提高发光器件光电性能和环境稳定性的纳米复合材料结构的设计及目前需要解决的问题。     

Electrooxidation and adsorption of oligoelthylene glycols on platinized platinum electrode

The trends in adsorption and oxidation of oligoethylene glycols (OEG), namely, di-, tri-, and tetraethylene glycol, on a Pt/Pt electrode are studied. Using a combination of methods of open-circuit potential shifts at the adsorption of organic species and anodic voltammetric curves, it is established that the OEG adsorption on a Pt/Pt electrode is accompanied by hydrogenation, dehydrogenation, and partial destruction of molecules and also that the amount and composition of accumulated adsorbate depend on the initial adsorption potential and the polymer structure. The OEG oxidation on a platinum electrode is considerably hindered as compared with ethylene glycol. The reaction rate decreases with an increase in the OEG molecular mass and is largely limited by the adsorption of molecules on the electrode surface, which is evidenced by the weak dependence of the rate on the potential in the double layer region.     

共注成型层厚分布影响因素分析

综合分析了聚合物熔体流变性能和过程参数对共注成型层厚分布的影响规律和影响机理，着重定性讨论了共注成型的多相分层流动的粘性包围（viscous escapulation)现象与界面不稳定性相互作用对层厚分布的 影响，并提出了基于三维粘弹性流动的机理模型是精确预测其相互作用机理的唯一途径。     

Ferroelectric Films

The preparation and properties of ferroelectric films are reviewed. Specific attention is directed to ferroelectric films prepared by wet chemical methods. Emphasis is placed on the microstructure and properties of SBT films for memory applications, and their dependence on chemistry and processing, as well as on the effects of chemistry and processing on the properties of piezoelectric and pyroelectric films. Emphasis is placed on recent results obtained in our laboratories, including modeling of the ferroelectric behavior of films and experimental results in each of these areas. Also considered is the use of ferroelectric films in memory, piezoelectric and pyroelectric devices of various types, with specific note made of the recently-announced use of pyroelectric sensors in automobiles.     

VPO催化剂的再生性质及其对晶格氧选择氧化丙烷的影响

采用脉冲反应器,研究了ＶＰＯ催化剂的再生性质及其对晶格氧选择氧化丙烷制丙烯酸和乙酸的影响,结果表明,ＶＰＯ催化剂与气相分子氧反应的速度要比丙烷与其 和氧反应的速度慢许多,因此以丙烷－Ｏ２共进料方式进行反应时,催化剂氧化再生是速度控制步骤,水是影响催化剂选择性的重要因素,但对活性影响不大,在反应温度下,水在ＶＰＯ催化剂 为可逆吸附,容易脱附流失,催化丙烷反应生成目的的产物的活性中心很稳定,主要是晶格     

负载Pd催化剂的表面碱性和NO吸附关系

催化消除汽车尾气中氮氧化物（ＮＯｘ）物种在大气环境保护方面有着重要意义．随着环保法规的越来越严格,研制活性更高,稳定性更好的 ＮＯｘ催化剂势在必行．贵金属 Ｐｔ、Ｐｄ、Ｒｈ三效催化剂（ＴＷＣ）能够同时去除 ＮＯｘｓ、ＣＯ、ＨｘＣｙ三种污染物,生产工艺比较成熟．其中Ｒｈ是公认的促使ＮＯｘ还原为Ｎ２的最有效组分,但Ｒｈ的价格较高且资源贫乏,限制了其实际应用．所以人们一直尝试采用一种廉价的替代品．单Ｐｄ的三效催化剂,由于其相对低廉的价格,较好的耐高温性能,有可能是合适的选择［１－２］．此外,以ＮＨ３为还…     

Electrocatalytic reduction of dioxygen at platinum particles deposited on Nafion- and clay-coated electrodes

Nafion- and clay-coated electrodes are prepared by casting a known amount of Nafion and clay solutions on the glassy carbon electrode (GC) surface. Subsequently platinum (Pt) particles are deposited on the GC electrodes and on the Nafion- and clay-coated GC electrodes. The formation of Pt particles on the modified electrode surface is analysed by scanning electron microscope, while cyclic voltammetry provides information on the anodisation of Pt particles deposited on the GC electrodes at >0.5 V(SCE) leading to the formation of platinum oxide (PtO). The involvement of PtO on the catalysed dioxygen reduction to hydrogen peroxide is reported. Macrocyclic cobalt(III) complex is also used as the electrocatalyst. The effect of pH on the reduction of PtO and dioxygen in deaerated and oxygenated solutions is studied to understand the dioxygen reduction processes. Received: 24 January 1997 / Accepted: 14 April 1997     

Interaction of activated carbon electrodes with sulfuric acid solutions

Impedance and potentiodynamic studies have been carried out to investigate reversible processes on the surface of electrodes based on activated carbon (AC). Relationships have been found between the reversible capacity and true resistance, on the one hand, and the potential, on the other. Stoichiometric characteristics of AC charging in sulfuric acid have been obtained. A mechanism of the reversible surface process is suggested. It is concluded that Faraday pseudocapacity makes a considerable contribution to charging of AC electrolytes. The amount of gas liberated in the course of AC wetting in electrolyte has been measured. It is assumed that the amount of liberated gas depends on the amount of active oxygen involved in the current-forming reaction. Based on the data obtained, a redox surface reaction is substantiated in general form.