Kinetic study of nickel(II) complexation by pteroylglutamic acid

The kinetics of the complexation of NiII by pteroylglutamic acid have been studied in the 545 ∘C range, the ionic strength (0.6 M) being regulated with KNO3, in the 5.5–7.0pH range, using the stopped-flow method. Under the experimental conditions two processes were observed. The faster process was detected in the millisecond range and is associated with the reaction between NiII and the ligand. The slower is observed within a few seconds. Complementary equilibrium studies were made at 25 ∘C. The results are consistent with the formation of a 1:1 complex between the reactants, and a mechanism is proposed to account for the observed behaviour. Equilibrium constants for the NiII plus pteroylglutamic acid system, as well as activation parameters, are reported. This revised version was published online in June 2006 with corrections to the Cover Date.     

The rotational mobility of fulleropyrrolineoxyl in toluene solution

The rotational mobility of a stable fullerene-based nitroxyl radical (fulleropyrrolineoxyl) in toluene was studied. The rotational correlation time of fulleropyrrolineoxyl was found to be about eight times longer than that of 4-oxy-2,2,6,6-tetramethylpiperidine-1-oxyl. The activation energy of the rotational motion of both probes was determined and their hydrodynamic radii estimated.     

Rheological and mechanical properties of ABS plastics prepared by bulk polymerization

A series of ABS plastics prepared by bulk polymerization was studied. The test samples contained almost equal amounts of PB but mostly differed in the molecular mass of a styrene-acrylonitrile copolymer. It was shown that the molecular mass of the copolymer strongly affects the rheological and mechanical properties of ABS plastics. An increase in molecular mass leads to a rise not only in the non-Newtonian viscosity of plastics but also in their yield point, storage modulus under periodic steady-state shear flow in the low-frequency plateau region, and impact strength. Quantitative correlations between these rheological and mechanical characteristics of the copolymers and their M _w values were established. As opposed to homophase polymer systems, a marked increase in the shear stress has no effect on viscosity in relation to the molecular mass of ABS plastics. In the case of melts, the influence of the M _w of the styrene-acrylonitrile copolymer on the rheological behavior of ABS plastics is apparently related to a change in the interaction of PB particles with the copolymer that controls the structural framework of the system. The relationship between the impact strength of the copolymer and its M _W may be explained by the fact that the latter parameter influences orientational effects in crazes that arise during steady-state shear flow of ABS plastics in the solid state.     

Analyzing electrochemical noise with Chebyshev’s discrete polynomials

The principles underlying a novel method intended for analyzing experimental data obtained when studying fluctuation processes are considered. The method in question is Chebyshev’s spectroscopy. The application of this method allows one to determine statistic characteristics of steady-state electrochemical noise against the background of severe deterministic interference without invoking the procedure of the fitting of the initial data. The potentialities of this novel method, which is intended for treating noise experiment, are demonstrated by examining model examples and analyzing the electrochemical noise generated by a lithium electrode placed in an aprotic organic electrolyte.     

Quantum-chemical study of degradation during stretching of small-molecule analogs of cis-and trans-polyisoprene segments by their end atoms

A change in the electronic structure and the influence of force on the deformation of molecules of cis-and trans-3-methylhex-3-ene under their stretching by application of a harmonic potential to the end carbon atoms was studied via the semiempirical quantum-chemical method PM3. The maximum force at which the molecule breaks was estimated; it was shown that this value is slightly dependent on the double bond configuration. With the use of molecular dynamics simulation, it was revealed that the local temperature of a molecule can rise to 1000 K during the degradation process.     

On the reduction of 1-aryl-2-oxo-1,2,3,6-tetra-hydro[1,4]diazepino[6,5-<Emphasis Type="Italic">b</Emphasis>]indole 4-oxides

Electrochemical reduction of 1-aryl-2-oxo-1,2,3,6-tetrahydro[1,4]diazepino[6,5-b]indole 4-oxides, 2-oxo-1-phenyl-1,2,3,6-tetrahydro[1,4]diazepino[6,5-b]indole, and 2-oxo-1-phenyl-1,2,3,4,5,6-hexahydro[1,4]diazepino[6,5-b]indole was studied. The results obtained were compared with previous data for the reduction of 4-oxides with formamidinesulfinic acid.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2715–2718, December, 2004.     

New phosphorus-containing macroheterocyclic cavitands

Previously unknown phosphorus-containing macroheterocycles were prepared from an accessible symmetrical dipentaerythritol derivative and trivalent phosphorus compounds. The difference in the properties of the phosphocycles containing one and two phosphoric functions was revealed.     

Investigation of Biopag films adsorbed on metal and ceramic surfaces by X-ray photoelectron spectroscopy

Using X-ray photoelectron spectroscopy, it was found that the treatment of aluminum, nickel, and ceramic surfaces with a 1% Biopag aqueous solution (Biopag, poly(hexamethylene guanidine chloride)), was synthesized at the Institute of Ecological and Technological Problems in accordance with TU (Specifications) 9392-020-41547288-02) results in the formation of thin polymer films on the surfaces. The chemical composition of the films was determined. It was shown that the chemical composition of the films is changed on long standing in air. Microbiological tests were carried out, and the minimum suppressing concentration toward Pseudomonas aeruginosa was determined. It was shown that the Biopag films aged for 6 months retain up to 84% of their initial activity.     

N,N′-Bis(trimethylsilylmethyl)thiocarbamide and N,N′-Bis(trimethylsilylmethyl)-λ6-thiocarbamide S,S-Dioxide

N,N′-Bis(trimethylsilylmethyl)-λ⁶-thiocarbamide S,S-dioxide was synthesized by oxidation of N,N′-bis(trimethylsilylmethyl)thiocarbamide with hydrogen peroxide. The synthesized dioxide is a less active reducing agent than previously studied S,S-dioxides of organosilicon thiocarbamides in which the silicon atom is separated from the thiocarbamide fragment by a -CH₂CH₂CH₂- bridge.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 6, 2005, pp. 912–914.Original Russian Text Copyright © 2005 by Vlasova, Grigor’eva, Voronkov.     

Sorption of Uranium from Sulfuric Acid Leaching Solutions by Strongly Basic Anion Exchangers

The equilibrium and kinetic characteristics of uranium sorption from simulated sulfuric acid leaching solutions by AMP, Lewatit K 6367, Purolite A 500, Purolite A 600, and AM-p gel-like and porous strongly basic anion exchangers were studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 5, 2005, pp. 736–740.Original Russian Text Copyright © 2005 by Kolomiets, Troshkina, Sheremet’ev, Konopleva.