纤维素醚的作用机理初探

研究了不同纤维素醚掺量时,自然养护条件下,砂浆的扫描电镜微观结构,以及荧光显微观察下,纤维素醚的失水固化作用机理。结果表明,在无外来水条件下,纤维素醚可显著提高砂浆的水化程度,随着纤维素醚掺量的增加,砂浆水化程度提高;将纤维素醚进行荧光染色处理,在荧光显微镜下观察纤维素醚的失水固化过程。其作用机理为：溶解后吸附大量水分...     

磁助捕集分离制样/X射线荧光测量微量Tc

建立了磁助捕集分离制样(MASP)/X射线荧光分析微量Tc的方法,使用磁化树脂作为固相捕集剂捕集溶液中的锝,利用外加磁场快速分离制样,实现捕集、分离及制样同时完成,可直接使用X射线荧光测量样品Tc含量。研究并分析了反应时间、磁化树脂用量、液相体积及酸度等因素对测量的影响,给出了推荐测量分析流程。使用磁助捕集分离制样,对Tc的检出限为0.33mg/L,满足PUREX流程1AW工艺点测量Tc的要求。     

无荧光防塌剂白沥青W-ASP的评价与应用

沥青及其改性产品具有良好的防塌性能和油层保护作用,因而被广泛应用,但其荧光干扰地质录井,毒性污染环境.研制开发出了一种无荧光环保型防塌剂--白沥青W-ASP.白沥青具有沥青及其改性产品的优点,又消除了沥青类产品毒性大、荧光级别高等缺陷.白沥青是高级脂肪醇树脂经水溶性加工后的一种产品,能与水、粘土发生乳化作用,在不同温度下能形成韧性粒子,堵塞地层微裂缝和渗透性地层的孔隙,起到降滤失、防止地层坍塌和保护油气层的作用,与沥青相比,它无荧光,不会干扰地质录井.在新疆准噶尔地区安集海河组复杂地层的应用表明,无荧光防塌剂具有降低高温高压滤失作用,抗温作用明显,能防止硬脆性泥页岩及无机盐类地层坍塌,井径规则,电测顺利,井下安全,易生物降解,无毒,是环保型钻井液添加剂.     

用于XRF测量微量Np的磁助分离制样方法

建立磁助捕集分离制样法,使用超顺磁性TiOA固相捕集剂捕集溶液中的镎,利用外加磁场快速分离制样,实现捕集、分离及制样同时完成,可直接使用X射线荧光测量样品中Np的含量。研究了反应时间、固相捕集剂用量、液相体积及酸度等因素对测量的影响,给出了推荐测量分析流程。使用磁助捕集分离制样,对Np的质量检出下限为0.12μg,质量浓度检出下限为0.04mg/L,满足Purex流程3EU工艺点测量Np的要求。     

氢化物发生-原子荧光光谱法测定工业磷酸中的铅

采用盐酸处理工业磷酸试样,用氢化物发生-原子荧光光谱法测定工业磷酸中的铅,对仪器条件、盐酸酸度、预还原剂用量、还原剂用量、共存元素干扰进行了试验,方法的检出限为0．028ug／L,测定精密度0．84％,回收率为98．9％-101．4％。建立的氢化物发生-原子荧光光谱法测定工业磷酸中的铅的分析方法具有操作简单,灵敏度高,重现性好等优点,能满足日常检验的要求。     

Effect of Heat Input on Fume Generation and Joint Properties of Gas Metal Arc Welded Austenitic Stainless Steel

 The effect of heat input on fume and their compositions during gas metal arc welding (GMAW) of AISI 316 stainless steel plates are investigated. Fume generation rate (FGR) and fume percentage were determined by ANSI/AWS F12 methods. Particle characterization was performed with SEM-XEDS and XRF analysis to reveal the particle morphology and chemical composition of the fume particles. The SEM analysis reveals the morphology of particles having three distinct shapes namely spherical, irregular, and agglomerated. Spherical particles were the most abundant type of individual particle. All the fume particle size falls in the range of less than 100 nm. Mechanical properties (strength, hardness and toughness) and microstructural analysis of the weld deposits were evaluated. It is found that heat input of 115 kJ/mm is beneficial to weld stainless steel by GMAW process due to lower level of welding fume emissions and superior mechanical properties of the joints.     

Influence of rare earth content on electrode kinetics in Misch metal-based AB5 MH alloys – Cyclic voltammetric investigations

The influence of lanthanum/cerium ratio (0.42–14.14) in Misch metal (Mm)-based AB₅-type hydrogen storage alloys has been investigated. The samples were subjected to X-ray florescence (XRF) and cyclic voltammetry (CV) studies. The metal hydride electrodes were assembled, and their discharge capacity was determined. These alloys delivered discharge capacity between 118 and 266 mAh/g. CV investigations threw light on charge-transfer reactions at the electrode/electrolyte interface and hydrogen surface coverage capacity. The CV parameters in general indicate that the battery activity increases with lanthanum/cerium ratio. At low lanthanum/cerium values, the discharge reactions proceed at potentials that are more negative. Furthermore, electrochemical reversibility of the hydrogen absorption–desorption on the alloy surface is enhanced at optimum lanthanum/cerium ratio as revealed by decreasing values of peak separation. The slopes of graphical plots of I_peak (anodic) vs. ν^1/2 for the fully charged samples reverse direction at very high lanthanum/cerium values. The results suggest that the discharge plateau is optimum at lanthanum/cerium ratio around 12.     

Determination of bisphenol A in canned fatty foods by coacervative microextraction,liquid chromatography and fluorimetry

Decanoic acid reverse micelle-based coacervates were used to provide simple, rapid and almost solventless extraction of bisphenol A (BPA) from canned fatty foods. The procedure involved the extraction of 200–400 mg of homogenised food sample with an aqueous solution containing 20% THF and 200 mg of decanoic acid, conditions under which the coacervate (around 550 µl) formed in situ and instantaneously. The overall sample treatment took about 30 min and several samples could be simultaneously treated using conventional laboratory equipment. No clean-up or solvent evaporation were required before determination of BPA by liquid chromatography and fluorescence detection. Recoveries in samples were between 90 and 99%, with relative standard deviations in the range 2–7%. The limit of quantification ranged 29–15 ng g^?1 for 200–400 mg of sample, being far below the current specific migration limit (SML) set by the European Commission (600 ng g^?1). The method was successfully applied to the determination of BPA in the solid content of canned fish (from 20 to 129 ng g^?1) and meat (from undetected to 37 ng g^?1).     

原子荧光光谱法测定饲料级硫酸铜中的砷

采用超纯水直接溶解样品,用原子荧光光谱法测定饲料级硫酸铜中的砷,对仪器条件、载流、还原剂、共存离子干扰等进行了研究。方法检出限为0.0593μg.L-1,回收率为98.5%～101.5%,相对标准偏差为0.56%。建立的氢化物发生-原子荧光光谱法测定饲料级硫酸铜中砷的分析方法具有操作简单,灵敏度高,重现性好等优点,能满足日常检验的要求。     

荧光探针法研究乳化剂对硅/丙核壳乳液聚合行为的影响

用荧光探针(芘)法测定了十二烷基硫酸钠(SDS)、烷基酚聚氧乙烯醚(OP-10),以及复配乳化剂的临界胶束浓度(CMC),并首次把荧光探针技术应用到硅/丙核壳乳液聚合反应的研究中.利用芘的I1/I3值,结合胶束微环境的极性变化规律和乳液聚合机理,探讨了乳化剂对聚合反应的影响.结果表明,荧光探针(芘)法可用于研究硅/丙乳液的聚合行为和确定乳化剂配比.通过粒径分析、透射电镜(TEM)对产品的结构进行了表征.