Vorticity addition method

It is shown that in the general case it is not possible to propose the Lagrangian viewpoint on the vorticity evolution, which would be unique for the entire flow, using the existing analogs of the Helmholtz theorems. This is related to the fact that, as distinct from the Helmholtz theorem oneself, these analogs are valid only for nonzero vorticity zones. New analogs of the Helmholtz theorems are proposed for the general case of flows (from incompressible fluid to viscous gas). They describe the vorticity evolution at all the points including the points of nonzero vorticity.     

Generalization of the Crocco Invariant for 3D Gas Flows Behind Detached Bow Shock Wave

Russian Mathematics - We study a steady 3D flow of the ideal gas. In the flow between the bow shock wave and the nose part of the body streamlined by the uniform supersonic flow, we consider...     

Photocatalytic Oxidation of Thiocianates in Aqueous Solutions

Russian Journal of Applied Chemistry - The kinetic patterns of the photocatalytic oxidation of thiocyanates by persulfate under the influence of quasi-solar ultraviolet radiation (UV) were...     

Determination of Microelements in Urine by the Method of Emission Spectrum Analysis with Application of a Fulgurator

The results of investigations of the microelemental composition of urine by the method of emission spectrum analysis are presented. The samples of urine under study were introduced into the arc discharge region by a fulgurator without preliminary preparation of the samples. The content of Pb in the urine samples at a concentration of about 10^–9 g/ml has been determined.     

Oxidation of azo dyes in aqueous solutions by combined methods

Fundamental aspects of the oxidative destruction of Orange III azo dye in aqueous solutions by integrated methods combining UV irradiation and iron-peroxide treatment were studied.     

Cavitational activation of the galvanochemical oxidation of phenol

Possibility of intensifying the galvanochemical oxidation of phenol under hydrodynamic cavitation conditions was studied.     

Comparison of the Results of Atomic Absorption and X-ray Fluorescence Analysis of Metals in Atmospheric Aerosols

Factors responsible for the systematic discrepancies between the results of atomic absorption (standard procedure) and X-ray fluorescence determination of metals in atmospheric aerosols preconcentrated on a filter were studied. Patterns describing the errors in the results of determining Fe, Cu, Pb, Zn, Mn, and Cr by the proposed procedures depending on the type of the metal compound and the concentration of SiO₂ in aerosol particles were found. It was shown that the underestimation of the results of atomic absorption analysis in comparison to those obtained by X-ray fluorescence is due to the incomplete decomposition of some analyte compounds and the adsorption of Fe, Cu, and Pb on the precipitated SiO₂.     

Vorticity on the Surface of an Axially Symmetric Body behind a Detached Shock Wave

Doklady Physics - The vorticity on the surface of an axially symmetric body streamlined by a steady unswirling homogeneous ideal gas supersonic flow with a detached shock wave has been studied. The...     

The effect of halogen substitution on the structure and electronic spectra of fluorone dyes

By means of the B3LYP density functional method with the use of the polarized continuum model PCM, we have performed quantum-chemical computations of the electronic absorption and fluorescence spectra of fluorone dianions: fluorescein, dibromofluorescein, eosin, erythrosine, and Rose Bengal in vacuum and methanol. We have revealed conformational features of the structure of fluorone dianions (charge redistribution, changes in the bond lengths and angles between bonds) second by the halogen substitution, the transition from the ground state to an excited state, and the change of the solvent (vacuum-methanol). Absorption and fluorescence wavelengths, constant dipole moments, transition dipole moments, and oscillator strengths have been calculated. We have showed that, upon halogenation of fluorones, the absorption spectra are redshifted and the Stokes shift decreases, which is qualitatively consistent with experimental results.     

Exact solutions of the Euler equations for some two-dimensional incompressible flows

Two-dimensional (plane and axisymmetric) steady flows of an ideal incompressible fluid are considered in a potential field of external forces. An elliptic partial differential equation is obtained such that each of its solutions is a stream function of a flow described by a certain solution of the Euler equations. Examples of such new exact solutions are given. These solutions can be used, in particular, for testing numerical algorithms and computer programs.