Anionic surfactant selective electrode for the titrimetric determination of anionic surfactant

The construction and characteristic performance of a PVC membrane electrode responsive for sodium dodecylsulfate (SDS) are described in this paper. The electrode based on CTA⁺DS^? ion pair as ionophore in PVC membrane displays a Nernstian slope of ?58.8 ± 0.7 mV/decade in a 1.32 × 10^?6 to 3.75 × 10^?3 mol L^?1 concentration range and a limit of detection of 1.13 × 10^?6 mol L^?1. The electrode can be used for 3 months without showing significant changes in the value of slope or working range. The electrode has been utilized as an end point indicator electrode for potentiometric titration involving Hyamine as titrant. More than 100 titrations were carried out for the evaluation of the electrode parameters: the standard deviations of the equivalent volume and the equivalent potential, the height of the potential jump and the number of faulty titrations. The behavior of the electrode was assessed with regard to their usefulness in routine analysis.     

Polypropylene/poly(butyl methacrylate) blends prepared by diffusion and subsequent polymerization of butyl methacrylate in isotactic polypropylene pellets

Polypropylene/poly(butyl methacrylate)(PP/PBMA) blends were prepared by diffusion and subsequent polymerization of butyl methacrylate(BMA) in commercial isotactic polypropylene(iPP) pellets.The diffusion kinetics,diametrical distribution of PBMA in a pellet and phase morphology of a typical PP/PBMA blend were investigated.     

UPLC-ELSD Determination of 1-Octacosanol in Raw Material and Health Products

Determination of the levels of 1-octacosanol is important in food stuff for the study of its pharmacological activities and health benefits. In this study, a novel, simple and fast internal standard method for the non-derivatization ultra-performance liquid chromatographic determination of 1-octacosanol in raw materials and health products was developed and validated based on evaporative light scattering detection. The linearity (r ² > 0.998), recovery (99.1–100.2%, RSD <2.7%), intra- and inter-day precision (RSD <3.8%), limit of detection (1.0 mg/L), limit of quantification (2.2 mg/L) of the 1-octacosanol were determined. The method was successfully applied to nine real 1-octacosanol products. The results of analyses had close agreement with the labeled claims of 1-octacosanol content in these products. Compared with the classical gas chromatography method, the developed method was simpler, faster and more environmentally friendly due to avoiding any derivatization step. This protocol represents a rapid and feasible method for quality control of 1-octacosanol products.

     

GaAs,GaP和GaAsxP1-x合金能带的计算

使用分区变分法计算了GaAs,GaP和GaAs_xP_1-x合金的能带。鉴于原胞内包含不同的原子,依据实际原子的大小,对不同原子球选用了不同的半径。晶体势用相应原子势的迭加势来计算。考虑到组成晶体时原子势场由于电子成键而产生畸变,因而在球外成键区选用了一些调整参数来调整势场,然后再用解析表式来逼近这种调整原子势。适当地选择调整参数使算得的能带同已知的实验值接近。对GaAs和GaP已算得了同实验结果符合的能带结构。使用所得的调整原子势进一步计算了GaAs_xP_1-x合金的能带。 关键词：     

ICM-界面流方法二维组件计算

本文介绍了ICM-界面流方法两维组件的计算。本计算不仅可以给出组件的临界值K_eff和平均通量,而且能够给出组件均匀化的能谱参数。用ICM方法验算了两个基准问题和几个工程实际问题,其结果与国外发表的以及国内蒙特卡罗方法计算的结果相比,均符合得很好。该程序可用于轻水堆两维组件的计算。     

磺胺二甲异恶唑与HSA的结合性质及其对HSA结构的影响

在模拟人体生理酸度条件下(pH 7.4),运用荧光、紫外、红外和圆二色光谱法结合分子模拟技术,研究了磺胺二甲异恶唑(SIZ)与人血清白蛋白(HSA)的相互作用。荧光猝灭实验表明,SIZ对HSA的荧光猝灭属于形成复合物的单一静态猝灭。SIZ与HSA有中等强度的亲合力,结合常数在104 L·mol-1数量级,结合位点数近似等于1,计算热力学参数焓变(ΔHΘ=-25.24kJ·mol-1)和熵变(ΔSΘ=-4.53J·mol-1·K-1)值表明,氢键与范德华力是SIZ与HSA相互作用的主要驱动力。荧光竞争实验表明,SIZ位于HSA亚结构域IIA的疏水空腔(Site I位),分子模拟证实了这一结果。紫外、同步荧光、圆二色谱和红外光谱分析以及蛋白质表面疏水性测定显示,SIZ与HSA结合诱导了HSA的二级结构发生了部分改变,蛋白质多肽链部分伸展,结构松散,使α-螺旋含量降低,HSA表面疏水性降低。 更多还原     

带临界指数的非线性椭圆型方程混合边值向题多解的存在性

本文讨论了有界区域上带临界指数的非线性椭圆型方程混合边值问题二对非平凡解的存在性，给出了存在二对非平凡解的条件.