The Andronov-Hopf Bifurcation with 2:1 Resonance

We consider dissipative dynamical systems in a neighborhood of quasi-periodic n-dimensional invariant tori that are not normally hyperbolic. We assume that the normal spectrum contains precisely two pairs of simple pure imaginary eigenvalues. We investigate the case where the frequencies are in the ratio 2:1. We establish sufficient conditions for the existence of invariant tori of dimension n + p in a certain region of the parameter space. Bibliography: 13 titles.__________Published in Zapiski Nauchnykh Seminarov POMI, Vol. 300, 2003, pp. 259–265.     

Ignition of a Fuel Mixture Using a Multipoint Pulsed Spark Discharge under Various Initial Conditions

Technical Physics - The development of efficient and reliable ignition systems for fuel mixtures is of interest for many practical applications associated with the use of combustion power plants....     

Calculation of the Width of the τ → K–K 0 ντ Decay in the Extended Nambu–Jona-Lasinio Model with Estimation of the Contribution from the Final-State Interaction

JETP Letters - The partial width of the $$\tau \to {{K}^{ - }}{{K}^{0}}{{\nu }_{\tau }}$$ decay has been calculated within the extended Nambu–Jona-Lasinio model including the contact and...     

Forms of solid solution ordering upon decreasing temperature

The work reports different forms of solid solution ordering: from the well-known atom redistribution processes over positions and the decomposition of the solid solution to the formation of superstructures, modulated structures, rotation of atomic groups, splitting of sites. For each ordering form as a crystal chemical phenomenon the position of atoms, molecules, and vacancies in the crystal structure of the solid solution is considered and the place of these processes among the main crystal chemical phenomena is determined. The manifestation of order–disorder processes in phase diagrams of systems is also analyzed: from the classical heterogeneous decomposition of solid solutions to the formation of ordered chemical compounds and other phase transitions. The necessity of a thorough study of the atomic-molecular nature of the solid solution ordering by modern X-ray diffraction crystallographic methods and high-resolution electron microscopy is demonstrated. For each ordering form examples are given, the driving force of the process is distinguished, and a brief literature review is presented.     

Preparation of reagent indicator papers with silver triangular nanoplates for chemical analysis

An impregnation method to prepare reagent indicator papers with silver triangular nanoplates (TNPs) is developed. The conditions for obtaining modified papers (type of paper, method for applying TNPs, and drying conditions) allowing for an acceptably uniform distribution of the TNPs are chosen. The spectral characteristics of the prepared materials are studied. The presence of an intense TNP surface plasmon resonance band in the diffuse reflectance spectra of the modified papers, which is linearly related to the content of the TNPs in the samples, as well as the lability of its position and shape in the presence of some substances, gives rise to the prospects of using the prepared materials as test-tools in chemical analysis.     

Numerical modeling of carbon monoxide neutralization by metered water injection into a high-temperature mixture of combustion products

A closed mathematical model of the flow of a two-phase mixture consisting of evaporating water droplets and a chemically reacting multicomponent gas is described. The effect of the real droplet heating and evaporationkinetics on the gas-phase chemical reactions in a mixture of combustion products is studied within the framework of this model.Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No.6, pp. 96–106, November–December, 1993.     

Reaction of divinyl selenide with secondary phosphine chalcogenides

Under the conditions of free-radical initiation (AIBN, UV irradiation), divinyl selenide regioselectively reacts with secondary phosphine sulfides and phosphine selenides to afford, depending on the ratio of the reagents, mono- or diadducts mainly of the anti-Markownikoff structure. The conditions which allow obtaining the diadducts in up to 97% yield are found. By the example of 2-{[2-(diphenethylphosphoroselenoyl) ethyl]selanyl}ethyl(diphenethyl)phosphine selenide the diadducts were shown to react with aqueous hydrogen peroxide at 53–56°C to give vinyl(diphenethyl)phosphine oxide in 76% yield.     

Influence of the temperature and cation nature on the EPR spectra of salts with the [Ni<Superscript>III</Superscript>(η<Superscript>5</Superscript>-1,2-B<Subscript>9</Subscript>C<Subscript>2</Subscript>H<Subscript>11</Subscript>)<Subscript>2</Subscript>]- anion

The influence of specific features of the structure and nature of the cations (Ph₄P⁺, H(Phen)⁺, Cs⁺, and (CH₃)₄N⁺) on the ERP spectra of the nickel ions in salts with the dicarbollylnickelate anion [Ni(B₉C₂H₁₁)₂]⁻ is studied. It is shown that the change in the cation type in these compounds results in the electron density redistribution, which affects the change in the main and average values of the g factor. The g _av value increases over that observed in frozen solutions upon the localization of the positive charge of the cation on one atom and in the absence of the screening effect of the solvent and large functional groups of the cation. The exception is the compound (Ph₄P⁺)NiCb₂⁻ (Cb is B₉C₂H₁₁) with solvated CCl₄ molecules. For all compounds studied, the temperature dependence of the linewidths in the EPR spectra is described by the equation ΔH = αT + βT⁷ with different α and β values and is defined by the temperature dependence of the relaxation process caused by the Raman interaction.     

Anomalous diffusion of water molecules in disperse mineral media

Gas adsorption relaxometry was used to study the effect of high-voltage nanosecond impulses on the structural condition of surfaces and the adsorption properties of sulfide minerals. It was established that the diffusion of water molecules into the samples was anomalous. An increase in time of impact of nanosecond impulses was accompanied by decrease in the time of adsorption equilibration.     

Heat capacity and thermal conductivity of Fe x Mn1 − x S single crystals

This paper reports on the results of investigations of the thermal properties and thermal conductivity of single crystals of homogeneous solid solutions Fe _x Mn_{1 ? x} S with a cubic NaCl structure, which have been prepared by the cation substitution for divalent manganese ions in manganese monosulfide. It has been revealed that the heat capacity and thermal conductivity exhibit anomalies in the range of the magnetic transition. The cation substitution is accompanied by an increase in the phase transition temperature.