Measuring the Electric Field Strength of Microwave Radiation at the Frequency of the Radiation Transition Between Rydberg States of Atoms 85Rb

Optics and Spectroscopy - The spectral characteristics of the resonance effect of the electromagnetic-induced transparency (EIT) of rubidium atomic vapors induced by intense radiation with a...     

Purification of the specific immunoglobulin G1 by immobilized metal ion affinity chromatography using nickel complexes of chelating porous and nonporous polymeric sorbents based on poly(methacrylic esters). Effect of polymer structure

Ni2+ complexes of the chelating nonporous and porous bead sorbents based on methacrylic esters crosslinked with ethylene dimethacrylate were used in isolation of the horseradish peroxidase-specific immunoglobulin IgG1 from the crude mouse ascitic fluid by immobilized metal ion affinity chromatography (IMAC). Iminodiacetic and aspartic acids were attached to porous poly(glycidyl methacrylate) beads differing in size, morphology and chemical composition. Ethylenediaminetriacetic acid and quinolin-8-ol chelating groups were attached mainly to the surface hydroxyl groups in nonporous poly(diethylene glycol methacrylate) beads through spacers. The latter sorbents exhibited better kinetic characteristics than the former but a very low IgG1 sorption capacity. In a single-step IMAC procedure, the best efficiency in the specific IgG1 purification was obtained with porous sorbents (recovery 92%, purity 73%). Differences in IMAC separations are discussed from the point of view of morphology of polymer beads as well as of the type and concentration of chelating ligands.     

On the concentration dependence of the sensitized phosphorescence quantum yield of naphthalene in toluene at 77 K

A concentration dependence of the sensitized phosphorescence quantum yield of naphthalene (with benzophenone as a donor) in equimolar toluene solutions at 77 K is studied for concentrations of components ranging from 0.1 to 0.5 mole/litre. A nonmonotonic character of this dependence is established. With increasing solution concentration, intervals of increase (from 0.1 to 0.35) and decrease (from 0.35 to 0.5) of the sensitized phosphorescence quantum yield are observed. Reasons for this dependence are discussed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 3–6, October, 2004.     

Structure of a new crystalline modification of 4-amino-5-ethoxymethyl-1,2-dimethylpyrimidinium iodide

The structure of a new crystalline modification (II) of 4-amino-5-ethoxymethyl-1,2-dimethylpyrimidinium iodide, C₉H₁₆IN₃O, the major product of methylation of 4-amino-5-ethoxymethyl-2-methylpyrimidine has been determined. The lattice parameters are a = 6.528(4) Å, b = 15.325(7) Å, c = 12.653(6) Å, γ = 97.57(50)°, sp. gr. P2₁/b, Z = 4, R = 0.0348 (over 1480 independent reflections). The molecule is planar. Its pyrimidine ring has the 2,5-diene structure and shows a weak tendency to adopt the C(2)-sofa conformation. Molecules in the crystal structure are linked into centrosymmetric dimers by N(8)-H?N(3) hydrogen bonds. These dimers, in turn, are linked into a three-dimensional framework by I^?-ions. The structure of modification II is compared with the structures of other 4-aminopyrimidines.     

Contents to Volume 32

Volume Contents

Contents to Volume 32     

Quantum-chemical investigation of the mechanism of transfer of a hydrogen atom in the phenol(NH2) complex

A quantum-chemical investigation of the mechanism of H atom transfer in the phenol(NH₂) complex was undertaken by the unrestricted Hartree-Fock and CASSCF(7e/7o) methods in the 6-31G(d) basis set. Low-lying structures representing two types of hydrogen bonds (classical and so-called πH bonds) were found. On the basic potential energy surface the transfer of H is realized through the conformational maximum of the isomer with a OH...N hydrogen bond and includes three stages, i.e., approach of the N and O atoms, the actual transfer of H, and relaxation of the O...HN hydrogen bond. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol, 35, No. 6, pp 331–337, November–December, 1999.     

Crystal and molecular structure of the membrane-active antibiotic enniatin C

The crystal structure of the cyclic hexadepsipeptide antibiotic enniatin C c[-(L-MeLeu-D-Hyi)₃-], C₃₄H₅₉N₃O₉, was established by X-ray structure analysis (sp. gr. P2₁, a = 20.205(5) Å, b = 8.702(2) Å, c = 25.587(6) Å, γ = 97.0(5)°, V = 4465.3(18) ų, Z = 4, R = 0.089 for 3601 reflections with I > 2σ(I)). The unit cell contains two independent molecules of enniatin C, one ethanol molecule disordered over two positions, and approximately two water molecules occupying four positions and forming hydrogen bonds with each other. The independent antibiotic molecules adopt virtually identical conformations similar to those observed in the structures of enniatin B and its Na,Ni-complex. These conformations are characterized by alternating upward and downward orientations of the carbonyl groups and pseudoequatorial orientations of side radicals. The Leu residues have stretched conformations. The N-methylamide groups of the independent antibiotic molecules face each other, whereas the molecules are displaced by approximately 8.4 Å with respect to each other along the mean planes of the rings.     

Crack formation under compression

This paper presents a theoretical analysis of the formation of a tensile stress zone (separation zone) in a crack of finite width under uniaxial transverse compression, assuming the existence of prefracture zones that satisfy a linear one-parameter relationship between stress and displacement vectors. A crack formation criterion is stated, and practical fracture criteria are analyzed from the point of view of locality of the crack formation process.Simferopol' University. Translated from Dinamicheskie Sistemy, No. 10, pp. 3–8, 1992.     

Transonic crossflow of condensing wet steam past a cylinder

The shadow and interferometric methods and the laser probe method are used to investigate crossflow past a cylinder on the free-stream Mach number interval M _a =0.5–1.2 for subcritical Reynolds numbers Re _d and various initial steam states. Detailed pressure distributions are obtained and the pressure fluctuations on the cylinder surface are measured. The dependence of the Strouhal number on the velocity and thermodynamic parameters of the flow are determined. In single-phase steam flow past a cylinder the greatest fluctuations occur in the separation zone in regimes corresponding to transonic drag crisis. It is shown that spontaneous condensation in the turbulent wake and local supersonic zones may cause an increase in the periodic pressure fluctuations in the separation zone, the maximum increase in the fluctuations being noted when the critical pressure ratio is reached at the rear of the cylinder. The initial wetness of the steam has the greatest effect on the periodic separation characteristics at subsonic flow velocities, and in the case of supersonic flow leads to a substantial increase in the level of the low-frequency pressure fluctuations at the front of the cylinder.(deceased)Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 6, pp. 118–138, November–December, 1994.     

Novel aurophilic organic ligands based on 1,3-dibromo-propan-2-ol and 2-aminothiophenol

The nucleophilic substitution reactions in 1,3-dibromo-propan-2-ol and the products of its acylation under the action of 2-aminothiophenol were investigated. It was shown that the resulting derivatives containing nitrogen and sulfur donor atoms form coordination compounds in the reactions with copper(II) salts. The possibility of chemosorption of the obtained ligands and complexes containing additional disulfide fragments on the gold electrode surface with the formation of an Au-S bond was demonstrated.