Deuteron electrodisintegration reaction and multiquark configurations

We have obtained the cross sections d³ and d² for the ed e'pn reactions with allowance for the contribution of the six-quark state (6q) of the deuteron in its wave function. It is shown that the presence of a 6q component as an admixture of 5% can cause the cross section for deuteron electrodisintegration to increase by a factor of 1.5–2 under certain kinematical conditions.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 45–50, July, 1985.In conclusion, we sincerely thank L. P. Kaptar', V. K. Luk'yanov, and A. I. Titov for numerous useful discussions and assistance in the work.     

1,3-dipolar cycloaddition reactions in the series of <Emphasis Type="Italic">N</Emphasis>-alkynyl-substituted uracils

Reactions of 1-(ω-bromoalkyl)-3,6-dimethyluracils and 1,3-bis(ω-bromoalkyl)-6-methyluracils with sodium azide gave the corresponding mono- and bis-azides. 1,3-Dipolar cycloaddition of the latter with prop-2-yn-1-ol, hex-1-yne, and dec-1-yne in the presence of copper(I) ions afforded acyclic and macrocyclic uracil derivatives containing 1,4-disubstituted 1,2,3-triazole fragments, which were subjected to quaternization with propyl iodide and methyl p-toluenesulfonate at the 1,2,3-triazole nitrogen atom.     

Supramolecular Systems Based on Novel Mono‐ and Dicationic Pyrimidinic Amphiphiles and Oligonucleotides: A Self‐Organization and Complexation Study

Novel mono‐ and dicationic pyrimidinic surfactants are synthesized and their aggregation behavior is studied by methods of tensiometry and nuclear magnetic resonance (NMR) self‐diffusion. To estimate their potentiality as gene delivery agents, the complexation with oligonucleotides (ONus) is explored by dynamic light scattering (DLS) and zeta‐potential titration methods and ethidium bromide exclusion experiments. Bola‐type pyrimidinic amphiphile (BPM) demonstrates rather a weak affinity to ONus. Although it induces mixed associations with ONus, only slight charge compensation changes occur at a large excess of bola, with no recharging reached. Similarly, the ethydium bromide exclusion study reveals a slow increase in the binding capacity toward an ONu with an increment in BPM concentration. The monocationic pyrimidinic surfactant (MPM) and its gemini analogue (GPM‐1) are ranked as intermediates in both their aggregative activity and complexing properties toward ONus. They both form mixed associates with ONus well below the critical micelle concentrations (cmcs) of 2 and 15 mM respectively. However, GPM‐1 has a much lower isoelectric point at the molar ratio surfactant/ONu r～1 compared to r～3 for MPM. This probably indicates a larger electrostatic contribution to the ONu complexation in the case of GPM‐1. The most hydrophobic pyrimidinic surfactant (GPM‐2), bearing three alkyl tails, demonstrates enhanced aggregative activity and binding capacity toward ONus as compared to former pyrimidinic surfactants. Due to effective aggregative (low cmc of 0.04 mM ) plus binding properties (fraction of bound ONu β=0.76 at r=2.5), GPM‐2 may be ranked as a promising agent for wider biological applications.     

Extraction of niobium with phenol-formaldehyde resol oligomer Yarrezin B from peroxide solutions

Extraction of niobium by nitrogen-containing phenol-formaldehyde resol oligomer Yarrezin B from peroxide sulfate solutions was studied. The stoichiometry of extraction was determined. The structure of the extracted complex Nb(O₂)(OH)O₂R(OH)N was predicted by molecular mechanics (MM) and molecular dynamics (MD) methods and the semiempirical ZINDO/1 method (single-point calculations) with the use of the HyperChem Release 8.0.4 program package.     

Near-field microwave diagnostics for medical applications

We study both theoretically and experimentally the possibilities of detecting malignant tumor inside a human body using near-field microwave probing. Our theoretical analysis is based on the developed theory of near-field diagnostics of plane-layered media. We verified this theory experimentally under controlled conditions of water-medium probing. Model calculations of recorded tumor contrast as a function of the size and depth of the tumor are performed. Two-dimensional images of an object imitating the tumor are obtained for different depths of object immersion in water.     

Solvent extraction of rhenium with N-(2-hydroxy-5-nonylbenzyl)-β-hydroxyethylmethylamine

Solvent extraction of rhenium from sulfuric acid solutions with aminophenol-class reagent N-(2-hydroxy-5-nonylbenzyl)-β-hydroxyethylmethylamine was studied. Solvent extraction stoichiometry was established. The structure of rhenium complex formed in solvent extraction with N-(2-hydroxy-5-nonylbenzyl)-β-hydroxyethylmethylamine was proposed on the basis of data of IR spectroscopy. Back extraction of rhenium with ammonia solutions was studied.     

Radiometry of dynamics of water-medium temperature profile by internal-wave transmission

Measurements of thermal radio emission at wavelengths of 3,9, and 30 cm are used to determine the temperature-distribution variations in the surface layer of a water medium by the excitation of internal waves in it.Scientific-Research Radio-Physics Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 36, No. 3–4, pp. 216–222, March–April, 1993.     

Synthesis and reactivity of acyclic and macrocyclic uracils bridged with five-membered heterocycles

Replacement of terminal atoms of Br in 1,3-bis(bromopentyl)-5(6)-substituted uracils with 2-mercapto-5-methyl-1,3,4-thiadiazole, 2,5-dimercapto-1,3,4-thiadiazole, 2-mercaptoimidazole, and 2-mercaptobenzimidazoles resulted in a series of acyclic compounds and isomeric heterocyclophanes. Structures of macrocyclic regioisomers were unambiguously determined by NMR data. One of the regioisomers exhibits a hypochromic effect with respect to model compounds. The acyclic uracils obtained bridged with five-membered heterocycles are alkylated with methyliodide and methyl tosylate, and oxidated with m-CPBA, H₂O₂, and I₂.     

Thermal degradation of polymethylsilsesquioxane and microstructure of the derived glasses

The present work aims to elucidate the physicochemical factors determining the microstructure of Si-O-C glasses derived from a polymethylsilsesquioxane powder pyrolyzed at 200-1300 °C in helium atmosphere. The pyrolysis behavior of the powder was studied by thermogravimetry coupled with mass spectrometry. The chemical composition of the glasses was determined by elemental analysis while the microstructure was studied by optical microscopy combined with scanning and transmission electron microscopy. The degradation of the polymer proceeds by a three-stage decomposition characterized by different mass losses as well as by different amount and type of evolved gaseous species. The derived glasses contain networks of pores and bubbles with diameters more than 0.1 mm. The increasing thermal treatment of the polymer above 200 °C does not lead to the disappearance of macropores. Micrometer-sized amorphous filaments are observed in porous interiors. A formation mechanism of pores and filaments is proposed. Polymer swelling accompanied by pore coagulation and gas release is believed to be responsible for the spatial separation of oligomers forming filaments.