Sensitivity and selectivity of the reaction of vanadium(V) with 4-(2-Pyridylazo)resorcinol on a solid support containing anion-exchange groups and modified with 8-hydroxyquinoline or 8-hydroxyquinoline-5-sulfonic acid

The effect of the modification of a solid support with 8-hydroxyquinoline (HQ) and 8-hydroxyquinoline-5-sulfonic acid (HQ-SFA) on analytical characteristics of the reaction of vanadium(V) with 4-(2-pyridylazo)resorcinol (PAR) on a solid phase was studied for polyacrylonitrile fiber filled with the AV-17 anion exchanger. Diffuse reflection spectra of the initial and modified supports and of vanadium(V) complexes of PAR on these supports were recorded. It was found that vanadium reacts with PAR on modified supports only in acid solutions. The conditions for the adsorption of vanadium and the dependences of the analytical signal on the acidity of the PAR solution and on the concentration of the modifier on the support were determined. The limits of vanadium detection by the reaction with PAR were calculated (0.5 and 1 ng/mL for AV-17-HQ and AV-17-HQ-SFA, respectively). The selectivity of the reaction of vanadium with PAR on modified supports was estimated with respect to copper, aluminum, iron(III), and zinc. It was found that the modification of the support with HQ and HQ-SFA impairs the analytical characteristics of the reaction of vanadium with PAR on the solid phase and that the use of modified supports for the color reaction of vanadium with PAR is inappropriat     

Selective sorption of protactinium on aminopolystyrene azo derivative chelating resins

The sorption of protactinium on chelating resins, containing arsono groups, or other salt-forming groups on an aminopolystyrene lattice, is discussed. The chelating resins were synthesized by coupling diazotizedp-aminopolystyrene witho-hydroxyphenylarsonic acid, 2-arsonobenzene-(1-azo-2)-1,8-dihydroxynaphthalene-3,6-disulphonic acid (Arsenazo I) and some other monoazo derivatives of chromotropic acid. The dependence of sorption of Pa, Zr, Nb and Ta was investigated from hydrochloric acid and sulphuric acid solutions under static conditions as a function of the concentration of the acid. The feasibility of separating Pa from Fe, U, Zr, Nb, Th and Po is shown, using a solution 10N in respect to sulphuric acid and 0.3M in respect to oxalic acid and employing a resin obtained by coupling diazotized aminopolystyrene with Arsenazo I.     

Discrete mathematical model of a sheet electron beam in a decaying magnetic field

A discrete model of a sheet electron beam is developed in a weakly relativistic approximation. A 3D simulation of the sheet electron beam with cyclotron rotation in an axially symmetric static magnetic field under time-periodic conditions of entry is performed. The velocity spread in the beam and the efficiency of converting the energy stored in the beam into DC power depending on the beam perveance are calculated.     

Nonlinear transverse-wave interactions in divergent axially symmetric magnetic fields

The dynamics of transverse-wave interactions in intense electron beams in divergent axially symmetric magnetic fields has been investigated by computer simulation. The case of a short magnetic field was analyzed. The conversion of electron-beam transverse waves in the presence of a decelerating electric field was considered.     

Determination of interdiffusion coefficients in melts from data on contact fusion

An efficient method of studying diffusion in metallic melts is contact fusion conducted in a nonsteady diffusion regime. The Matano-Boltzmann method, which in principle solves the problem of determining interdiffusion coefficients, is very time-consuming and has a low accuracy. Well-known theoretical methods involve assumptions which are not always justified. Here we propose a method of calculating interdiffusion coefficients, the position of the Matano surface, and the concentration profile from data on the width of the liquid layer obtained by contact fusion for a certain period of time and the compositions of the liquid at the boundary with the crystals. The results for the systems Sn-Bi and Ga-In, obtained by computer calculation using the proposed method, are in agreement with well-known empirical data.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 54–58, October, 1986.     

Spectrophotometric determination of lead in environmental objects with the new highly effective reagent HOCAC

Summary A simple method has been developed for determination of traces of lead with the new organic reagent HOCAC (hexaoxacycloazochrom). The method was used for lead determinations in waters, soils and food after extraction or sorption of the lead followed by direct reagent addition to the acid re-extract or eluate. It is possible to determine Pb down to 2 g in 1 l water after extraction or down to 10 g in 1 l water and down to 500 g in 1 kg potatoes or soil after sorption.     

Effect of Anions on the Development of Color Reactions of Cadmium, Lead, and Mercury with Dithizone and 4-(2-Pyridylazo)resorcinol on a Fibrous Material Filled with the Anion Exchanger AV-17

The effect of nitrates, chlorides, iodides, sulfates, thiosulfates, thiocyanates, acetates, tartrates, nitrilotriacetates, and ethylenediaminetetraacetates in the sorption of Cd(II), Pb(II), and Hg(II) and their subsequent determination with dithizone and 4-(2-pyridylazo)resorcinol (PAR) on the solid phase of a fibrous anion-exchange sorbent filled with AV-17 was studied. The dependences of the analytical signals of complexes adsorbed on the solid phase on the concentration of anions in the solution and on the stability of anionic complexes were revealed. The analytical signals in the sorption and determination of Cd, Pb, and Hg with dithizone and PAR on the solid phase were maximum for iodide and thiosulfate complexes. Conditions of the sorption of Cd(II), Pb(II), and Hg(II) were found for their subsequent total and separate determination with PAR and dithizone.     

Pseudo-diffusion mode of contact melting in the presence of electro-migration

The growth rate of the liquid contact layer may be influenced by an electric current at contact melting. Depending on the direction, the electric current speeds up or slows down the liquid layer growth in comparison with the diffusion regime (no-current mode). It is shown that if the current flowing in the "accelerating" direction is decreased inversely proportional to the square root of time, the time law of the liquid layer growth will be identical to the diffusion mode. The proposed pseudo-diffusion mode is implemented for the bismuth-indium system at 75°C. Results of calculations of the mobility and the effective charge of the melt ions are presented.