Spectrophotometric determination of microamounts of scandium with o-chlorophenylfluorone and cetyltrimethylammonium bromide

The reaction of scandium(III) with o-chlorophenylfluorone (o-CIPF) in the presence of cetyltrimethylammonium bromide (CTMAB) has been studied. In an acetate buffer at pH 4.4, a red-purple complex is obtained, with maximum absorption at 569 nm and a molar absorptivity of 1.31 x 10(5)1.mole(-1).cm(-1). The composition of the complex is found to be 1:2:2 Sc-o-CIPF-CTMAB. Beer's law is obeyed over the range 0-12 mug/25 ml scandium. The proposed method has been used for determination of trace scandium in tungsten ores after its prior separation by solvent extraction.     

Infrared-optical properties of vapour-deposited metal films

Spectroscopic infrared ellipsometry was applied to determine the optical constants of thin metal layers deposited on dielectric substrates such as glass or CaF(2). The layers were produced by evaporating gold or silver in a vacuum, and the coverage, that is the deposited mass per area, was chosen in the range 80-1200 mg m(-2) for gold, which refers to thicknesses in the lower nanometer range; in the case of the specifically lighter silver, about half the coverage was applied. At low coverage a metal island structure is obtained, which gives rise to surface-enhanced infrared absorption (SEIRA). Depending on the coverage, the deposited films exhibit either dielectric or metallic optical properties. Atomic force microscopy and conductivity measurements complement the spectroscopic observation.     

催化动力学光度法测定痕量锆

研究了在弱酸性介质中，锆（Ⅳ）催化过氧化氢氧化铬蓝黑Ｒ这一新的指示反应及其动力学条件，建立了一种高灵敏、高选择性测定痕量锆的新方法，方法检出限为３．７４×１０－１１ｇ／ｍＬ，线性范围０～１．１μｇ／２５ｍＬＺｒ（Ⅳ）．用于合金钢中痕量锆的测定，结果满意．     

Zn—TppS4极谱络合物吸附波的研究：中草药天麻,川芎,当归中锌的测定

锌是人体必需的微量元素之一。它具有重要的生理功能和营养作用,是合成脱氧核糖核酸(DNA),核糖核酸(RNA)和蛋白质必需的金属离子。锌是DNA,RNA聚合酶等80多种酶的组成成分及激剂,直接影响细胞代谢,免疫过程,细胞分裂和再生。最近美国有人提出缺     

Enzymatic surface modification of Kevlar fibers

Horseradish peroxidase catalyzed grafting of acrylamide (AM) onto Kevlar fibers has been studied. The modified fiber has been characterized with scanning electron microscopy (SEM), elemental analysis and the grafting yield. From the SEM micrographs, the surface of the grafted Kevlar fiber is rougher than that of the untreated fiber, and the elemental analysis indicated that the nitrogen content of the treated fibers is higher than that of the untreated fiber. All the results suggested that AM must have been grafted onto the Kevlar surface through HRP-mediated radical initiated grafting reaction. The probably mechanism of HRP catalyzed grafting of AM onto Kevlar surface is proposed.     

羟基羧酸钛(Ⅲ)配合物的合成和热性质研究

三氯化钛分别与苹果酸铵、酒石酸铵和柠檬酸铵反应，制得三种新的固态配合物：苹果酸羟基钛(Ⅲ)、酒石酸羟基钛(Ⅲ)和柠檬酸钛(Ⅲ)(化学式分别为Ti(OH)(C₄H₄O₅)·1.5H₂O、Ti(OH)(C₄H₄O₆)·1.5H₂O和Ti(C₆H₅O₇)·1.5H     

Electrospun cellulose acetate fibers: effect of solvent system on morphology and fiber diameter

This paper reports an investigation of the effects of solvent system, solution concentration, and applied electrostatic field strength (EFS) on the morphological appearance and/or size of as-spun cellulose acetate (CA) products. The single-solvent systems were acetone, chloroform, N,N -dimethylformamide (DMF), dichloromethane (DCM), methanol (MeOH), formic acid, and pyridine. The mixed-solvent systems were acetone–DMAc, chloroform–MeOH, and DCM–MeOH. Chloroform, DMF, DCM, MeOH, formic acid, and pyridine were able to dissolve CA, forming clear solutions (at 5% w/v), but electrospinning of these solutions produced mainly discrete beads. In contrast, electrospinning of the solution of CA in acetone produced short and beaded fibers. At the same solution concentration of 5% (w/v) electrospinning of the CA solutions was improved by addition of MeOH to either chloroform or DCM. For all the solvent systems investigated smooth fibers were obtained from 16% (w/v) CA solutions in 1:1, 2:1, and 3:1 (v/v) acetone–DMAc, 14–20% (w/v) CA solutions in 2:1 (v/v) acetone–DMAc, and 8–12% (w/v) CA solutions in 4:1 (v/v) DCM–MeOH. For the as-spun fibers from CA solutions in acetone–DMAc the average diameter ranged between 0.14 and 0.37 μm whereas for the fibers from solutions in DCM–MeOH it ranged between 0.48 and 1.58 μm. After submersion in distilled water for 24 h the as-spun CA fibers swelled appreciably (i.e. from 620 to 1110%) but the physical integrity of the fibrous structure remained intact.     

Studies on metal — protein interactions: Inter-comparison among various approaches

Binding ability of mercury, thallium, lead and bismuth with Erythrina variegata seed protein have been investigated using tracer packet technique. Due to the lack of standard methods, inter-comparisons have been made among three different approaches, like trichloroacetic acid (TCA) precipitation, isoelectric precipitation and dialysis of protein after incubation with the metals. Good agreement was observed for all the cases except that of lead.     

A new method for inversion of hydroxyl group of carbocyclic nucleosides

The hydroxyl group of carbocyclic nucleosides was inversed when the compounds were treated with Me_3SiCl,KCN and a catalytic amount of NaI in DMF/CH_3CN.