Home – Home – Jornals – Advanced Search

The thermal conductivity of gaseous 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea) was studied over the temperature range from 300 to 423 K at pressures up to 2.4 MPa. The measurements were carried out with a steady-state coaxial-cylinder method. The purity of samples used throughout the measurements was 99.4 mol %. The uncertainties in the obtained thermal conductivity data are estimated to be less than

This paper studies one of the methods for production of a hydrophobic surface. This study is based on the method, which allows substitution of the polar hydroxyl group ((

The equations are formulated for the transfer of particles of bidisperse suspension in a disk centrifuge with regard for the interaction of particles with each other and with ambient liquid. The effect of initial concentration of particles on their sedimentation velocity and the sediment layer formation are studied. A possibility is shown for the formation of an internal wave of concentration of small particles as the result of the entrainment of small particles by large particles. The applicability of the formula for numerical differentiation is shown, which describes the temporal variation of particles concentration to determine sedimentation velocity.

The problem of acid deposition in West Siberia is discussed on the basis of the data on the ion composition of atmospheric aerosol, precipitation and surface waters, obtained for different natural climatic zones (from the tundra in the north to the steppe in the south) in 1996

Results of 3 year-long studies of the biogenic component of the atmospheric aerosol in the south of West Siberia using terrestrial measurements and aircraft monitoring of the atmosphere and analysis of collected snow cover samples are presented. The seasonal dynamics of the content of components of this biogenic component has been obtained, their possible local and remote sources have been determined. It has been demonstrated that maximal and minimal values of concentration of total protein in the atmosphere differ by about an order, and the concentration of microorganisms does so by more than 2 orders. At the same time, the found values are quite consistent with literature data for other regions. On the basis of the data obtained, it is hypothesized that the main contribution to the biogenic component of the atmospheric aerosol even during the spring-summer period is made not by local, but by remote sources of bio-aerosols. Mathematical models are proposed which permit making definite conclusions about the localization of these sources. It is demonstrated that the greatest influence on this region is exerted by the sources situated in Middle Asia and North-West Kazakhstan.

On the basis of the known theoretical developments, a sufficiently simple model of local scale has been built and software-supported, which uses as the input information the normative databases on industrial sources and accessible climatic information. Bibliographic sources and general principles of model construction are considered, and the calculation results are compared with data of experimental studies of some industrial objects and cities of the Kemerovo Region.

Experimental data on annual variability of 7

The results of investigation of the interaction of halogen-containing organic compoungs (HOCs) with magnesium, aluminium and silicon oxides of industrial and laboratory preparation in the dark and under the action of sunlight in the troposphere are presented. The chemical composition of these oxides corresponds to the main components of solid atmospheric aerosol. The experimental results are the evidence that fluorine- and chlorine-containing organic compounds containing also hydrogen atoms are destructively photosorbed on MgO exposed for a long time in the air, magnesium halides being formed as a result of photosorption. The rate of photosorption for fluorine-containing hydrocarbons is several times higher than that for chlorine-containing hydrocarbons. The amount of hydrochlorofluorocarbons (HCFCs) photosorbed at room temperature and pressure of 1 Pa can exceed 15 % of the monolayers of MgO surface. The interaction of magnesium oxide with HCFCs leads to their removal from the atmospheric air under tropospheric conditions till the residual HCFC pressure less than 10

The elemental and phase composition of the surface layers of atmospheric aerosol (AA) particles sampled in winter 1998 in Irkutsk, Listvyanka and Ulan-Ude, is investigated by means of secondary ion mass spectrometry. It is stated that the source of AA is erosion of aluminosilicate soil. The surface of AA particles is covered by adsorbed hydrocarbons, nitrogen-containing compounds and partially by organic particles with a size of about 30 nm.

A brief review of works on the development of the system of mathematical modeling of processes in the atmosphere and on the assimilation of the data of meteorological observations is given. In addition, the works on the applicability of the Kalman filter theory to the problem of the assimilation of observation data are reviewed.