Electrooxidation of Methanol and Ethylene Glycol Mixture on Platinum and Palladium in Alkaline Medium

The performance of mixture of methanol and ethylene glycol (EG) oxidation has been studied on both Pt and Pd electrodes in alkaline medium. The activity of EG oxidation is better than that of methanol oxidation and the stability of EG oxidation is better than that of methanol and ethanol oxidation on the Pd electrode. The onset potential for ethanol oxidation is more negative 200 mV than that of EG, however the stability of EG oxidation on the Pd electrode is better than that of ethanol oxidation. The performance of methanol oxidation improves pronouncedly by adding a small amount of EG on both Pt and Pd electrodes. The onset potential and peak potential of mixture of methanol and EG oxidation are close to or more negative than that of sole methanol and EG oxidation on the Pd electrode. The mixture of methanol and EG is more easily to be electrochemically oxidized and gives a better performance than sole methanol and EG on the Pd electrode. The results show that the mixture of methanol and EG is a promising candidate as fuel in direct alcohol fuel cells.     

污垢组成、布基、去污条件对去污力评价的影响

介绍了在Ｌａｕｎｄｅｒ－Ｏｍｅｔｅｒ去污机中“Ⅲ类”浓缩粉和标准粉对人工皮脂污布和标准污布的去污力,讨论了污垢组成,基质和洗涤条件对去污力的影响,进一步,将此种去污力与实际污布在洗衣机中的去污力进行了比较。结果表明,人工皮脂污布在Ｌａｕｎｄｅｒ－Ｏｍｅｔｅｒ去污机中的洗洒结果更换近实际污布在洗衣机中的洗涤结果。     

超临界水降解聚丙烯的工艺研究

采用间歇式管式反应器进行了超临界水降解聚丙烯实验,研究了影响聚丙烯降解的因素。实验结果表明,在温度400－450℃、压力23－35MPa及反应时间60－120min的条件下,超临界水能有效地降解聚丙烯。反应温度和反应时间是影响聚丙烯降解的主要因素,温度越高、时间越长,聚丙烯降解越彻底;聚丙烯颗粒度越小降解速率越快,粉末原料在温度400℃、反应时间60min时,以油相产物为主;在温度450℃、反应时间120min时,有利于得到气相产物。     

Influence of size and shape on optical properties of cesium tungsten bronze: An experimental and theoretical approach

Although the optical properties of nanocrystalline cesium tungsten bronze have been widely studied, there is a lack of research on the effect of particle size on its optical properties. In order to further investigate size and shape effect on the NIR shielding performance, cesium tungsten bronze nanoparticles with different sizes and morphologies were prepared by two methods. The size of irregular shaped samples prepared by solvothermal method is tens of nanometers, while the size of hexagonal prism shaped samples prepared by solid state reaction method is hundreds of nanometers. The element spectrums shows that there are more oxygen vacancies in large particles than in small particles. The NIR shielding performance of large particles far lower than that of small particles, indicating that the influence of shape and size on optical properties is more obvious than that of oxygen vacancy. Theoretical calculation on hexagonal prism shaped particles exhibits that the NIR extinction of large aspect ratio is better at longer wavelength and small aspect ratio is better at shorter wavelength.     

Uterine Micro-Environment and Estrogen-Dependent Regulation of Osteopontin Expression in Mouse Blastocyst

Embryo implantation is a highly synchronized bioprocess between an activated blastocyst and a receptive uterus. In mice, successful implantation relies on the dynamic interplay of estrogen and progesterone; however, the key mediators downstream of these hormones that act on blastocyst competency and endometrium receptivity acquisition are largely unknown. In this study, we showed that the expression of osteopontin (OPN) in mouse blastocysts is regulated by ovarian estrogen and uterine micro-environment. OPN mRNA is up-regulated in mouse blastocyst on day 4 of pregnancy, which is associated with ovarian estrogen secretion peak. Hormone treatment in vivo demonstrated that OPN expression in a blastocyst is regulated by estrogen through an estrogen receptor (ER). Our results of the delayed and activated implantation model showed that OPN expression is induced after estrogen injection. While estrogen treatment during embryo culture in vitro showed less effect on OPN expression, the tubal ligation model on day 3 of pregnancy confirmed that the regulation of estrogen on OPN expression in blastocyst might, through some specific cytokines, have existed in a uterine micro-environment. Collectively, our study presents that estrogen regulates OPN expression and it may play an important role during embryo implantation by activating blastocyst competence and facilitating the endometrium acceptable for active blastocyst.     

缩聚反应过程相对分子质量分布的在线检测

以聚酯缩聚反应过程为对象,用发生函数法建立在线相对分子质量分布估计模型。为了符合缩聚釜的实际效应,采用有约束优化方法在线校正模型参数,并用现场数据进行仿真计算。仿真结果表明,本模型预估的MWD在正常工况下与工厂设计数据吻合,并能不断给出整个缩聚流程的质量信息,对聚酯缩聚过程相对分子质量分布进行预估是有效的。     

Quantitative aspects of nitrogen nutrition in crops

The processes affecting the response of crops to nitrogen fertilizers are reviewed, with special emphasis on quantitative relationships that enable the development of deterministic models. Total dry matter production is described in terms of length of the growing period and average growth rate, and the effect of nitrogen status of the vegetation on both is discussed. Attention is paid to nitrogen influence on stomatal response and crop water use. It is shown that the effect of differential nitrogen nutrition can in some cases be described in terms of light interception, but not always. It is concluded that the present insight in the relevant processes is insufficient to use deterministic models directly for application in fertilizer practices at the farm level, but that further development of such models is an important aid in structuring thinking about the system.     

Settling velocity of droplets in turbulent flows

Two parameters of particle or droplet dynamics which are of importance in describing their behaviour in turbulent pipe flows are their settling velocity and eddy diffusivity. It is usually assumed that the settling velocity in turbulent flow is equal to that in still fluid and on the basis of this assumption the eddy diffusivity is usually determined experimentally from the distribution of droplets or particles in horizontal turbulent flow. Since the settling velocity has a strong influence on the resultant value of the eddy diffusivity, the influence of turbulence on settling velocity is investigated in this work. A simple stochastic model of settling in turbulent flow is developed and it is shown that a considerable retardation of still fluid settling velocity is possible for a wide range of conditions.     

Catalysis and Alternatives to Liquid Fuels

The refining of liquid fuels from petroleum has arguably had a larger effect on the field of (non-enzymic) catalysis than any other industry, so much so that both the engineering and social norms resulting from, and supporting the petroleum industry now affects both the agenda and problem-setting goals in the alternative fuels industry and consequentially in catalysis. For example, there is great emphasis today on the development of biofuels that resemble in their properties and operation gasoline and diesel. I argue that this is not necessarily the most prudent manner of using biomass as a fuel source and propose that it is more prudent and efficient to convert biomass to electricity directly. If adopted, this would have a vast effect on vehicle design, on electrical distribution strategies and investments and consequently on the pathways that research programs in catalysis are likely to follow, replacing current emphases on producing and improving liquid fuels with ones affecting such processes as combustion, and battery and other electrical storage and distribution issues.     

Study of the hypophosphite effect on the electrochemical reduction of nitrobenzene on Ni

The effect of the hypophosphite ion on the electrochemical reduction of nitrobenzene on Ni was evaluated from a cyclic voltammetric study and from constant potential electrolysis in an aqueous-ethanol alkaline medium. The results were compared with the data obtained in an hypophosphite-free solution. It was found that in an hypophosphite containing solution an unusual selective reduction of nitrobenzene to nitrosobenzene occurs. It is the first time that nitrosobenzene is detected as the reaction product of the nitrobenzene electrochemical reduction in an aqueous-ethanol solution. It is proposed that the Ni modified surface which is formed upon hypophosphite oxidation is responsible for the non reducibility of nitrosobenzene. The effect of the electrode potential on the nitrobenzene electrolysis on a Ni modified electrode was analysed. It was concluded that the highest nitrosobenzene yield (33%) and selectivity (82%) is achieved at −1.1 V. It was also found that the formation of nitrosobenzene leads to an electrode poisoning effect in the electrolysis process.     

微肋结构对储罐失压下液化气瞬态暴沸特性的影响

沸腾液体蒸气膨胀爆炸（BLEVE）是液化气储运中的一类常见灾害,其爆炸剧烈程度取决于容器失压时亚稳态液体的过热度。为避免发生液化气爆炸,提出了一种采用微肋结构来促进过热液体成核的防制思路。通过搭建可视化的实验装置,对比观测了失压条件下光滑和微肋表面上的气泡成核过程,并测量了失压后容器内的瞬态压力曲线。结果表明,微肋表面上的成核起始时间相比光滑表面提前了50 ms;在200～500 kPa泄放压力范围下,通过采用微肋结构表面,暴沸引发的压力反弹相比光滑表面降低了24.1%,液体最大过热度下降了21.7%。     

Gradient Hydroxyapatite Chromatography with Small Sample Loads. III. Fundamental Differential Equation for Gradient Chromatography

Abstract

In contrast to stepwise Chromatography, with gradient Chromatography, it is impossible in principle for a chromatographic process to be described on the basis of a continuity equation for the actual molecular flux occurring on the column itself. It is the abstract molecular flux occurring on the mplarity gradient of competing ions that is fundamental. From this point of view it is not the column but rather the molarity gradient of the ions that is fixed; both the sample molecules and the “gradient” which is defined as an assembly of longitudinal positions on the column migrate on the molarity gradient. A continuity equation for the abstract flux is proposed. It is confirmed that the theoretical chromatogram obtained in an earlier paper is a solution of this equation.     

Comparison of bound rubber and swelling in silicone rubber/silica mixes and in silicone rubber vulcanizates

Unextracted polymer and liquid absorption values have been determined on unvulcanized silicone rubber/silica mixes and on unfilled silicone rubber vulcanizates, for comparison of the two different types of three-dimensional structure which must exist. In both types, the amount of rubber extracted on immersion in liquid is dependent on the expansion of the respective network but only in the former is the amount dependent on the method of extraction; this is attributed to interaction between filler and rubber continuing as a result of immersion. Even at equilibrium, the amount of unextracted polymer can be greater than that of bound rubber. In some mixes, liquid absorption is substantially constant during extraction of considerable amounts of soluble rubber. This is attributed, in the presence of filler, to a dependence of the absorption on the previously postulated interparticular rubber which, in turn, is dependent on the mean distance between filler particles. Although unextracted polymer is also dependent on that mean distance, it is proposed that this is a secondary effect of network expansion by the absorbed liquid. As some published values of bound rubber have undoubtedly been of unextracted polymer, these results help to explain published differences of opinion on the value of bound rubber for investigation of filler reinforcement phenomena.     

Increased Expression of Ephrins on Immune Cells of Patients with Relapsing Remitting Multiple Sclerosis Affects Oligodendrocyte Differentiation

The effect of the inflammatory response on regenerative processes in the brain is complex. This complexity is even greater when the cause of the tissue damage is an autoimmune response. Multiple sclerosis (MS) is an immune-mediated disease in which demyelination foci are formed in the central nervous system. The degree of repair through oligodendrocyte regeneration and remyelination is insufficient. Ephrins are membrane-bound ligands activating tyrosine kinase signaling proteins that are known to have an inhibitory effect on oligodendrocyte regeneration. In this study, we examined the expression of ephrins on immune cells of 43 patients with relapsing-remitting (RR) MS compared to 27 matched healthy controls (HC). We found an increased expression of ephrin-A2, -A3 and -B3, especially on T cell subpopulations. We also showed overexpression of ephrins on immune cells of patients with RR-MS that increases the forward signaling pathway and that expression of ephrins on immune cells has an inhibitory effect on the differentiation of oligodendrocyte precursor cells (OPCs) in vitro. Our study findings support the concept that the immune activity of T cells in patients with RR-MS has an inhibitory effect on the differentiation capacity of OPCs through the expression and forward signaling of ephrins.     

超声波对苯酚在NKAⅡ树脂上吸附平衡的影响

本文以苯酚水溶液／NKAⅡ树脂吸附体系为实验对象,研究超声波对液固吸附平衡的影响。分别测定了在超声场和无超声场条件下,苯酚在NKAⅡ树脂上的吸附等温线,报道了在超声场条件下苯酚在高聚物吸附剂上的吸附等温线。研究结果表明：超声场作用下的吸附平衡等温线要低于在常规条件下的吸附等温线,超声场强度越大,苯酚在吸附剂上的吸附容量就越小。向吸附体系施加超声场,会导致吸附体系的温度升高。超声场对吸附平衡的影响是由超声场的热效应和非热效应所引起的,而后者的影响要大于前者。向液固吸附体系添加乙醇或乙酸乙酯作为第三组分,能进一步使体系的相平衡关系朝着吸附量减少的方向移动,这种变化在超声波场条件下更为明显。     

An experimental technique for determining the significance of intraparticle diffusion in an aging catalyst

The effects of simultaneous decay and diffusion on a first order reactiion have been investigated. Two limiting types of behaviour are observed. In the first, cumulative conversion on diffusion limited catalysts is shown to behave in a manner opposite to that expected if the catalyst were non-aging, in that conversion decreases with decreasing particle size. The other extreme shows behaviour consistent with that observed on a non-decaying catalyst; that is, conversion increases with decreasing catalyst size. Experimental evidence for such behaviour is observed with cumene cracking and gas oil cracking, both on zeolite catalysts. As a consequence of the above observations, it is proposed that a new test involving experimentation at constant cat/oil ratio and over a range of space velocities be used to determine the significance of intraparticle diffusion on a catalyst subject to decay.     

钙元素对褐煤热解和气化特性的影响

综述了钙元素对褐煤热解和气化特性的影响,讨论了钙元素对热解产物中挥发分、焦油产率和气体产物分布的影响,以及对褐煤半焦气化的催化作用。结果表明,与酸洗煤相比,热解过程中,钙元素降低焦油产率,提高半焦产率;气化过程中,钙元素的植入提高褐煤半焦的反应活性,缩短了反应时间。高温时钙元素主要以氧化态的形式存在,低温时则不断与半焦基体键合而参与交联反应,少部分挥发。     

富含钙磷的多孔氧化钛膜及其生物活化机理

在不同电压下,钛经微弧氧化在表面形成富含钙磷的多孔氧化钛膜。通过模拟体液浸泡实验检测磷灰石的形成以确定样品的生物活性。实验结果表明：不同电压制备的微弧氧化样品在模拟体液浸泡后,只有400 V和450 V的样品表面生成磷灰石层,说明高电压制备的样品具有生物活性;而低电压制备的微弧氧化样品在模拟体液中浸泡长达50 d仍未见到任何物质沉积,表明其不具有生物活性。分析认为,粗糙多孔的表面虽有利于磷灰石的成核,但高电压下出现的CaTiO_3相及其水解吸引钙、磷沉积才是磷灰石形成的主要原因。     

不同造粒核芯的包膜控释肥的性能及肥效研究

土柱淋溶试验表明,油冷造粒包膜控释肥16 d时的氮素累积溶出率低于转鼓造粒核芯控释肥大约为21.2%。电镜观察表明,油冷造粒工艺制得的复肥颗粒外表面比转鼓造粒工艺制得的复肥光滑,且前者核芯紧实度优于后者。大田试验结果表明,在等养分条件下,施油冷造粒包膜控释肥处理的花椰菜长势、产量及生物量均优于转鼓造粒包膜控释肥,增产幅度达26%,且前者的氮素利用率和土壤有效氮均高于后者。研究表明,不同核芯造粒工艺对包膜控释肥的控释性能有明显影响。