亚硫酸根在纳米铂-金/多壁碳纳米管修饰电极上的电化学行为及其测定

采用滴涂法和电化学共沉积法制备了纳米Pt-Au和多壁碳纳米管(MWCNTs)修饰玻碳电极(纳米Pt-Au/MWCNTs/GCE),采用循环伏安法(CV)研究了亚硫酸根在纳米Pt-Au/MWCNTs/GCE上的电化学行为。结果表明:在磷酸盐缓冲溶液(PBS)中,亚硫酸根在纳米Pt-Au/MWCNTs/GCE上产生了较明显的氧化峰。亚硫酸根的氧化峰电流与亚硫酸根的浓度在1.0×10~(-6)~2.0×10~(-3) mol/L的范围内呈现良好的线性关系(r=0.9936),检出限为1.0×10~(-7) mol/L(S/N=3)。该检测方法灵敏、简便、线性范围宽,可以用于实际样品中亚硫酸根的测定。     

Pt-Fe(Ⅲ)/多壁碳纳米管修饰电极测定亚硫酸根

为建立一种简便、快速的亚硫酸根分析方法,采用滴涂法和电化学沉积法制备Pt-Fe(Ⅲ)/多壁碳纳米管(MWCNTs)修饰玻碳电极(Pt-Fe(Ⅲ)/MWCNTs/GCE),通过循环伏安法研究亚硫酸根在该修饰电极上的电化学行为,并优化实验条件,在此基础上建立一种伏安法测定亚硫酸根的新方法。亚硫酸根的氧化峰电流与其物质量浓度在8.0×10-6~7.0×10-3mol/L范围内呈良好的线性关系(r=0.998 9),检测限为3.0×10-6 mol/L,水样中亚硫酸根的加标回收率在98%~102%之间。该方法具有操作简便、分析速度快和线性范围宽的优点,可用于实际样品中亚硫酸根的测定。     

纳米薄膜厚度的X射线测量

研究了通过小角度X射线衍射(XRD)技术测量纳米薄膜沉积厚度与沉积速率的方法,并测定了在SiC表面沉积Fe纳米薄膜的厚度和沉积速率。结果表明,采用小角度XRD技术测量纳米薄膜厚度和沉积速率,能克服基片性质、表面平整度和金属膜氧化的影响,准确、方便地测量纳米薄膜的厚度和沉积速率。     

X射线激光Nd，Dy,Er和Yb薄膜靶表面氧化过程的石英晶振方法研究

用电子束蒸发方法在抛光玻璃衬底上分别制备了X射线激光用的稀土元素Nd ,Dy ,Er和Yb薄膜靶。用石英晶片作为陪片 ,通过测量晶振频率的方法研究了薄膜靶在真空、干燥空气及潮湿空气等不同环境中不同阶段的氧化层增长过程。发现除Yb薄膜在淀积结束后的干燥空气和潮湿空气环境中的氧化过程遵循倒对数规律之外 ,其它所有的氧化过程均可用对数规律很好地进行拟合。淀积结束后充入大气时 ,薄膜表面的快速氧化过程仅为数分钟。在相同的环境中 ,Nd氧化速率最高 ,Er和Dy其次 ,Yb最低 ;在不同的环境中 ,Nd受环境湿度的影响最大 ,Er和Dy其次 ,Yb最低。     

c取向YBa2Cu3O7—δ超导外延膜进脱氧过程

用电阻法测量了ＹＢａ２Ｃｕ３Ｏ７－δｃ取向外延膜进脱氧过程,结果表明在氧含量变化较小的情况下,进氧、脱氧速率相近,用Ｘ射线衍射方法证明了ＹＢａ２ＣＵ３Ｏ７－δｃ取向外延膜电阻率与氧含量成指数关系,获得氧化学扩散激活能久为０．９ｅｖ。     

水基氧化石墨烯纳米流体的制备及稳定性研究

以去离子水为基液,在无任何分散剂的情况下将氧化石墨烯悬浮于水中,用超声波处理器进行超声振荡,制备出稳定无聚沉的水基氧化石墨烯纳米流体。测试了纳米流体的STEM图像,分析了其粒径分布。对纳米流体的表面Zeta电位进行了测量,并结合DLVO悬浮理论和双电层结构进行稳定性分析,阐明了氧化石墨烯纳米流体能够长期保持稳定性的机理。     

基于偶氮苯的亚硫酸氢根比色传感器的设计与研究

报道了基于偶氮苯的化合物AZO-1,可作为比色传感器,实现对亚硫酸氢根的"裸眼"检测。在化合物AZO-1的溶液中加入HSO3-离子之后,亚硫酸氢根可与醛基发生亲核加成反应,导致分子内电荷转移效率发生改变。相应地,溶液最大吸收峰从465nm蓝移至410nm,由红色变为黄色,且该变化过程肉眼可见。借助紫外-可见分光光度计,化合物AZO-1对HSO3-的检测灵敏度可达4.6μmol/L。而且,得益于化学反应的专一性,该传感体系可实现对亚硫酸氢根的特异性识别与检测,对其它的阴离子则无明显响应。     

散热方法对材料导热系数测量的影响和不确定度分析

文章讨论了用稳态法测量橡胶材料的导热系数的过程中,如果散热方法不同.稳态时材料的上下表面的温度就不同;测量散热盘的冷却速率的方法不同则得到的散热速率就不同.在三种不同的散热速率测量中,当散热盘在自然环境中散热时测得的导热系数的精度较高.     

多壁碳纳米管的非等温氧化动力学及机理

本文研究了通过CVD法制得的缺陷多壁碳纳米管（MWNTs）在不同升温速率（5,10,15,20K／min）下的非等温氧化行为。热重分析仪记录了MWNTs在非等温氧化过程中的质量变化,DTG曲线则表征了MWNTs的氧化速率。供用TEM观察了MWNTs的缺陷及氧化过程的修饰情况。本文还讨论了气固反应公式在MWNTs氧化动力学计算中适用性。结果表明：当MWNTs的杂质含量充足的情况下,氧化速率在不同的升温速率下都为常数,这说明,氧化速率在一定的温度下总保持一个最大值。绎修正的气固反应公式可以用来计算MWNＴs的氧化反应活化能。     

亚硫酸钙氧化为石膏的研究

进行了亚硫酸钙氧化为二水石膏的研究 ,考察了初始 p H值、反应温度、空塔气速、固含量和停留时间对氧化率的影响 ,给出了适宜的反应条件 .在这些条件下 ,氧化率达 96 %以上     

Novel homogeneous catalyst system for the oxidation of concentrated ammonium sulfite

A homogeneous catalyst system made up of [Co(NH3)6]2+/I- has been put forward to catalyze the oxidation of concentrated ammonium sulfite. The experiments were performed in a packed column with sulfite concentrations above 2.5 mol l(-1), temperature range 20-65 degrees C, and oxygen partial pressure 0.052-0.21 atm. The experimental results indicate that the Co(NH3)6(2+)/I- homogeneous catalyst system can obviously accelerate the concentrated ammonium sulfite oxidation rate. After 2h reaction, the sulfite conversion is only 12.5% with no catalysts while 72.1% sulfite conversion can be obtained with 0.02 mol l(-1) Co(NH3)6(2+) and 0.005 mol l(-1) I- in the ammonium sulfite solution. The sulfite oxidation rate increases 284% as Co(NH3)6(2+) concentration increases from 0.01 to 0.02 mol l(-1). But there is little use increasing the Co(NH3)6(2+) concentration above 0.04 mol l(-1). The sulfite oxidation rate may increase 229% as the temperature increases from 20 to 65 degrees C. Sulfite oxidation rate is independent of the initial sulfite concentration. Increasing the oxygen partial pressure can increase the sulfite conversion. The reaction order with respect to oxygen is 1.2 and sulfite is zero. The apparent activation energy determined is 23.5 kJ mol(-1).     

光电经纬仪摄影参数对胶片成像质量影响的分析

以调光参数的选择为重点，从高和调焦两个方面分析了778光电经纬仪和160电影经纬仪有关摄影参数对胶片成像质量的影响，并针对靶场实际应用，给出了摄影参数选择的基本原则和具体操作方法，进行了参数调整和拍照实验，获得了成像质量较高的胶片。     

Mechanism of the “Hydrazine Effect” Caused by N'-acyl-N-phenylhydrazine

N'-acyl-N-phenylhydrazines are known to cause an increase in speed and contrast of photographic development of silver halide grains. This “hydrazine effect” is attributed to the formation of phenyldiazene, being a strong nucleating agent. The overall mechanism is explained by the three successive reaction processes, namely, (1) oxidation of N'-acyl-N- phenylhydrazine, (2) removal of the N'-acyl group from N'-acyl-N-phenyldiazene by base catalyzed hydrolysis, and (3) nucleation of phenyldiazene to unexposed or underexposed silver halide grains. The oxidation of N'-acyl-N-phenylhydrazine is effected by the oxidation products of the developing agent such as p-bcnzoquinone and p-benzoquinone-2-monosulphonate. Of the three reactions, the process (2) is rate limiting, being influenced by the nature of the N'-acyl group and the alkalinity of the developer.     

制版显影液活性和稳定性的探讨

本文考究和分析了制版硬性影液在温度和硫氧用量不同的条件下，其照相性能在显影液保存过程中的变化情况。     

The Influence of Halide on the Silver-Catalysed Oxidation of N,N-Dimethyl-p-phenylenediamine by [CoIII(NH3)5Cl]2+

The mechanism of the silver colloid catalysed oxidation of N,N-dimethyl-p-phenylenediamine by Co^III(NH₃)₅Cl₂₊ was studied in the presence of halides in aqueous solution at a pH of about 5. The silver colloids were prepared by reduction of silver nitrate with ascorbic acid or with sodium boranate in the absence of a special stabilizing agent. The course of the reaction could easily be followed in a double wavelength photometer because of the strong absorbance of p- semiquinonediimine, the first oxidation product of p-phenylenediamine. Both the reaction rate and the irreversible course of the reaction depend on the kind and the concentration of halide present in the solution. Apart from the electrocatalytic redox reaction, the oxidative formation of silver halide by cobalt (III) and the reduction of this silver halide by p-phenylenediamine occur simultaneously. Therefore, the mechanism of at least three important photographic processes can be studied at the same time in this redox system.     

各类现场摄影清晰范围的控制技巧

目的研究各类现场摄影清晰范围的控制技巧，达到使现场照片拥有足够的清晰范围的目的。方法首先确定要拍摄的范围，即每一张照片具体要反映哪一段空间范围；然后选择镜头和机身、选定每一张照片的合适的拍摄点；最后用小光圈控制获得大景深。结果各类现场摄影的清晰范围可以控制。讨论现场摄影的特点是要求足够的清晰范围，现场摄影不仅仅要求保证画面的主体清晰，更重要的是必须设法控制足够的清晰范围。     

Direct electron transfer of heme- and molybdopterin cofactor-containing chicken liver sulfite oxidase on alkanethiol-modified gold electrodes

Direct heterogeneous electron transfer (ET) of sulfite oxidase (SOx), a heme- and molybdopterin cofactor-containing intermembrane enzyme, was studied on alkanethiol-modified Au electrodes both with SOx entrapped between the modified Au electrode and a permselective membrane and with SOx adsorbed at the electrode surface, in the absence of any membrane. SOx in direct electronic communication with the electrode surface gave a quasi-reversible electrochemical signal with a midpoint potential of--120 mV vs Ag/AgCl corresponding to the redox transformations of the heme domain of SOx and with a heterogeneous ET constant in the order of 15 s(-1). The efficiency of the bioelectrocatalytic 2e- oxidation of sulfite catalyzed by SOx in direct ET exchange with the electrode was shown to depend essentially on the nature of the alkanethiol layer. Adsorption and orientation of SOx on an 11-mercapto-1-undecanol (MuD-OH) self-assembled monolayer, i.e., terminally functionalized with OH groups, provided efficient catalytic oxidation of sulfite, contrary to nonfunctionalized alkanethiols, e.g., 1-decanethiol, or alkanethiol layers terminally functionalized with NH2 groups. Comparative studies with short-chain alkanethiols, e.g., cysteamine and 2-mercaptoethanol, revealed an evidently different mode of adsorption of SOx on these layers, onto which SOx was not catalytically active. Coadsorption of MuD-OH and 11-mercapto-1-undecanamine improved the surface properties of the SAM, resulting in a higher surface coverage with bioelectrocatalytically active SOx but not in an increased apparent catalytic rate constant, kcat, ranging in the order of 18-24 s(-1) at pH 7.4. The achieved efficiency of SOx bioelectrocatalysis in direct ET reaction between the modified electrode and the enzyme approached the rates characteristic for the catalysis mediated by cytochrome c, the natural redox partner of SOx, thus implying the retention of the biological function of SOx under the heterogeneous electrode reaction conditions. Results obtained enable the development of a third-generation biosensor for sulfite monitoring.     

The limits of the use of the ultra high speed Cranz-Schardin camera,direct shadow visualization of a fracture

This paper shows the limits in using the Cranz-Schardin high speed camera for photographing catastrophic fracture in materials with strong photoelastic constants. There is a maximum permissible distance between the sample and the observation plane if one wishes to use the elastic and elastic-plastic fracture theories. We develop a shadow method in which successive pictures of the fracture are superimposed on a photographic plate set near the sample. The results allow an accurate quantitative measurement of either the fracture propagation or the energy of fracture.