Characteristics of radionuclide contamination of different zones of Semipalatinsk Nuclear Test Site “Opytnoe pole”

Data on the spatial distribution of radionuclides (²⁴¹Am, ²³⁹Pu, ¹³⁷Cs and ¹⁵²Eu) formed during nuclear explosions of different types near P2 SNTS test site are presented. Radionuclide contamination induced by the explosions varies in the concentrations of individual radionuclides, their proportions and species. Examination of the variations is a crucial task to plan remediation activities as well as those aimed at decrease of radiation risk for population and prevention of repeated contamination. Concentrations of ²⁴¹Am and ^239+240Pu that are the most toxic radionuclides in the area lie in hundred thousands of Bqkg^?1. The most contaminated areas are classified by the radionuclide concentration, ratio and form present in soil.     

Thermodynamically stable fractal-like domain structures in magnetic films

A fractal-like structure of the domain boundaries was revealed in “overcritical” uniaxial Permalloy magnetic films. The fractal dimension of domain boundaries at the film surfaces was determined as a function of the film thickness. It is shown that the phase transition between the two possible types of fractal-like structures is accompanied by a jump in fractal dimension.

     

Supramolecular systems based on poly(ethyleneimines) and calix[4]resorcinarenes with alkylphosphonate fragments. Aggregation and catalytic activity

Aggregation in poly(ethylenimine)-calix[4]resorcinarene-water-DMF systems was studied by the methods of conductometry and dynamic light scattering. The sizes (radii) of the aggregates formed and the critical micelle concentrations were determined. The catalytic activity for these systems in the hydrolisys of phosphorus acid esters was shown. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 924–931, May, 2007.     

The Influence of Triton X-100 on Protolytic Properties of Aminomethylated Calix[4]resorcinarene and Its Interaction with Copper(II)

The influence of Triton X-100 (concentration 5 mM) on acid-base properties of aminomethylated calix[4]resorcinarene (H₈L) containing alkyl (R¹ = C₁₁H₂₃) and dimethylaminomethyl (R² = CH₂N(CH₃)₂) substituents and interaction of H₈L with copper(II) is studied by potentiometry and mathematical simulation of equilibria in solutions. It is found that the presence of a nonionic surfactant favors the aggregation of H₈L (the degree of aggregation is higher than four), whereas, in 80% isopropanol at the same pH ≈ 10.2, a neutral species of the compound is only dimerized. The addition of Triton X-100 affects both the composition and stability of formed copper(II) complexes. The fraction of the highly charged tetranuclear [Cu₄(H₄L)]⁴⁺ complex sharply decreases. The formation of a large amount of [Cu(H₇L)]⁺ complex appears to be preferable compared to [Cu(H₈L)₂]²⁺ complex containing two ligands in the coordination sphere (pH ≈ 5.7). An enhancement of the acidic properties of protonated species of the compound and a decrease in the apparent constants of H₈L-copper(II) complex formation in Triton X-100 solutions compared to those in water-alcohol solutions are attributed to the formation of mixed micelles.__________Translated from Kolloidnyi Zhurnal, Vol. 67, No. 4, 2005, pp. 527–533.Original Russian Text Copyright © 2005 by Sal’nikov, Boos, Ryzhkina, Lukashenko, Tiforova.     

Temperature dependence of coherent oscillations in Josephson phase qubits

We experimentally investigate the temperature dependence of Rabi oscillations and Ramsey fringes in superconducting phase qubits. In a wide range of temperatures, we find that both the decay time and the amplitude of these coherent oscillations remain nearly unaffected by thermal fluctuations. In the two-level limit, coherent qubit response rapidly vanishes as soon as the energy of thermal fluctuations k(B)T becomes larger than the energy level spacing variant Planck's over h omega of the qubit. In contrast, a sample of much shorter coherence times displayed semiclassical oscillations very similar to Rabi oscillation, but showing a qualitatively different temperature dependence. Our observations shed new light on the origin of decoherence in superconducting qubits. The experimental data suggest that, without degrading already achieved coherence times, phase qubits can be operated at temperatures much higher than those reported till now.     

Synthesis,Self-Association,and Solubilizing Ability of an Amphiphilic Derivative of Poly(ethylene glycol) Methyl Ether

A new amphiphilic derivative–methoxy(polyethoxy)ethyl stearate has been synthesized with the goal of creating therefrom systems for delivery and enhancement of bioavailability of piperine. The aggregation and solubilizing properties of ω-methylpoly(oxyethylene) stearate have been studied by means of a set of physicochemical methods.     

Aggregation and catalytic properties of polymer-calix[4]resorcinarene-water-dimethylformamide systems

The aggregation in poly(ethylene imine) (poly(ethylene glycol))-calix[4]resorcinarene-water-dimethylformamide (30 vol %) systems and the catalytic activity of these compositions in hydrolysis of 4-nitrophenylbis(chloromethyl)phosphinate are studied by conductometry, tensiometry, lightscattering, and viscometry. Critical association concentrations, hydrodynamic radii of polymer-colloid aggregates, and kinetic parameters of hydrolysis are determined.     

Phosphorylation of polyethyleneimine in the solutions of calyx[4]resorcinolarene and its mixture with the surfactant

Phosphorylation of alkylated polyethyleneimine in chloroform in the presence of alkylated calyx[4]-resorcinolarenes with 2-hydroxyethoxy- and phosphorus-containing substituents and cetyl(3-hydroxypropyl)-dimethylammonium bromide was studied by means of the UV spectrophotometry. It was found that the character and the degree of the effect of calyxarene and its mixture with the surfactant depend on the hydrophobicity of macroring and the ratio of concentrations of components in the solution. The increase in the content of calyxarene and decrease in the concentration of polymer leads to the transformation of the catalytic action into the inhibiting one.     

Supramolecular catalytic systems based on 1, 4-diazabicyclo[2.2.2]octane,its alkylated quaternary derivatives,and lanthanum nitrate

Spectrophotometry was used to study the catalytic effects of the systems composed of N-monoand N, N-dialkylated 1, 4-diazabicyclo[2.2.2]octanes and lanthanum nitrate on the hydrolysis rate of O-alkyl O-4-nitrophenyl chloromethylphosphonates (Alk = Et, Buⁿ, and n-hexyl). The mechanism of action and efficiency of the catalytic system depend on the structure of the heterocycle, its propensity to aggregation and complexation with the lanthanum cation, and the relative content of the components in solution. The maximum catalytic effect (a ～115-fold increase in the hydrolysis rate constant) was achieved in micellar solutions of the cationic monoalkylated derivative of 1, 4-diazabicyclo[2.2.2]octane and lanthanum nitrate.