Home – Home – Jornals – Journal of Applied Mechanics and Technical Physics 2012 number 3

The mechanism of reverse motion of a vacuum arc cathode spot in an external magnetic field is explained based on a description the spot and its surroundings as a localized set of slow magnetosonic waves. Reverse motion of this plasma perturbation results from the anomalous dispersion property of slow magnetosonic waves. The transverse displacement component of the cathode spot is oriented in the direction of transverse motion of the total energy flux. The proposed mechanism can be one of the competing mechanisms of reverse motion and can be used to construct new models for the reverse motion of cathode spots.

A mathematical model that describes a one-dimensional approximation of interrelated processes of unsteady deformation of plane, cylindrical, and spherical packets of metallic woven grids and wave processes in the gas contained in pores is presented. Nonlinear equations of dynamics of two interpenetrating continua are solved numerically with the use of a modified Godunov scheme. Solutions of problems of the shock wave impact on plane and cylindrical packets of grids are obtained. Numerical results are found to agree with available experimental data. The character of explosive waves passing through a cylindrical packet of grids is studied.

The dynamics of a "collective" gas bubble in the magma melt during its decompression was numerically studied on the basis of a complete mathematical models of an explosive volcanic eruption. It is shown that the bubble size distribution obtained for the nucleation process has one peak, which allows considering a "collective" bubble. The main stages of bubble growth due to gas diffusion and changes in the viscosity of the medium are determined. It is shown that the high viscosity of the melt makes possible the transition from the Rayleigh equation to a simpler relation for the radial velocity of the bubble.

Results of experimental and numerical investigations of the effect of gas injection through a permeable porous surface on the drag coefficient of a cone-cylinder body of revolution in a supersonic flow with the Mach number range M_h = 3-6 are presented. It is demonstrated that gas injection through a porous nose cone with gas flow rates being 6-8% of the free-stream flow rate in the mid-section leads to a decrease in the drag coefficient approximately by 5-7%. The contributions of the decrease in the drag force acting on the model forebody and of the increase in the base pressure to the total drag reduction are approximately identical. Gas injection through a porous base surface with the flow rate approximately equal to 1% leads to a threefold increase in the base pressure and to a decrease in the drag coefficient. Gas injection through a porous base surface with the flow rate approximately equal to 5% gives rise to a supersonic flow zone in the base region.

Receptivity of a viscous shock layer on a flat plate aligned at an angle of attack to external multiwave acoustic perturbations is studied. It is shown that external acoustic waves and periodic controlled perturbations introduced from the surface of the plate mounted at an angle of attack smaller than 20^o generate entropy-vortex disturbances with a similar spatial distribution in the viscous shock layer. This result allows numerical implementation of the interference method of controlling disturbances generated in the viscous shock layer on the plate by external acoustic waves at one frequency and at a spectrum of frequencies by introducing blowing-suction perturbations on the plate surface with appropriate amplitudes and phases.

Vegetational changes, namely pyrogenic, lithogenic, floodplain, Aeolian, and waterlogging, are briefly characterized. Fire events are among the basic ecological factors determining the differentiation of plant cover and vegetation diversity over the territory under consideration.

New procedure was proposed for the investigation of atmospheric radioactivity in the surface air layer through evaluation of specific activity of artificial and natural radionuclides in aerosol sink. Dry deposition of aerosol particles was described. Collection of aerosol is carried out using a passive sampler in which chemically inert fibrous and powdered materials are used as sorption substrate. Analysis of experimental results characterizing the features of radionuclide distribution in aerosol sink during their introduction into coniferous tree stand is presented.

Threshold concentrations of elements in fresh water necessary for the survival of Spirogira sp. were determined.
The concentrations of sodium, potassium, calcium, magnesium in the algae was maintained at a level of (84,3 ± 0,8), (23,9 ± 0,5), (3,5 ± 0,2), (8,5 ± 0,2) mmol/kg of dry mass, respectively, and water (92,5 ± 0,21) %. It was shown that the threshold concentrations of sodium, potassium, calcium, magnesium in water, determining the boundaries of the range of Spirogyra sp. in fresh water reservoirs are equal to 0,003-0,007, 0,002-0,003, 0,0017-0,0022, 0,0012-0,0018 mmol/l, respectively. A decrease in water mineralization was accompanied by a substantial increase in the gradient of cation concentration between the algae and the environment, thus enhancing the load on the systems maintaining water-salt metabolism. It was shown on the basis of comparative analysis that Spirogyra sp., being the primary link of the trophic chain, possesses a more efficient ability to extract ions from water in comparison with freshwater animals.

This article deals with the results of the study of diatom algae of lake Shira. The list of found algae contains 95 species (including subspecific taxa - 126). Brief ecological and geographical anаlysis of the algal flora is made.

In the studied waterbodies of the north-east of Western Siberia, Bacillariophytas dominаte in the flora of planktonic organisms by species abundance. Among them, class Pennаtophyceae is distinguished by the highest species richness. The first electro-microscopic studies of pinnate diatom algae allowed obtaining complete data on the species composition of Pennаtophyceae at the modern level. 213 taxa from 53 genera including 98 new for the region, 56 new and rare for the flora of Russia and forms identified only to the genus have been found. The taxonomy of the genera Nitzchia, Stauroneis, Pinnularia, Navicula s.s. is the most rich.

Mass vegetation of cyanobacteriae Spirulina fusiformis Woronich. was discovered during the examination of shallow lake Solyonoe situated at the territory of Omsk. Large resources of the raw biomass of spirulina in summer make it possible to use the lake as a source of valuable biological raw material.

Complexes of microscopic fungi of seven polliniferous species at an apiary in the Zalesovo District of the Altay Territory were studied during two years with different weather conditions. A comparative analysis of fungal cenoses of vegetative, generative organs and pollent grains of plants was carried out.

The human selenium status in 32 districts of Omsk region was determined, serum selenium being in the range 73-116 µg/L. An indirect correlation was found between serum selenium concentrations and whole mortality, malignаncy from lung cancer, ovarian cancer and rectal cancer. Significant differences in selenium accumulation coefficient in plants were shown to depend on the type of soil. Methods of the human selenium status optimization are discussed.

Results of the investigation of qualitative composition and relative concentrations of readily volatile compounds of needles in two natural pine populations situated in the forest-steppe zone in the south of Middle Siberia are presented. The number of components distinguished is 89. Anаlysis of intra- and interpopulation variability of 31 terpenoids (of mono- and sesquiterpene fractions) was carried out. The spatial structure of the dispersion of signs was anаlyzed. Reliable interpopulation differences in the concentrations of the majority of compounds were marked. It was established that worsening of growth conditions inside populations causes an increase in the mass concentration of light-weight monoterpene compounds, especially α-pinene, a decrease in the qualitative diversity of the components of volatile oils. Groups of terpenoids with relative content connected to different extents with interpopulation differences and diversity of conditions for tree growth inside populations were distinguished.

The dynаmics of damage and litter of the needles of pine Pinus sylvestris (L.) and spruce Picea obovata Ledeb.  P. abies (L.) Karst. in the basin of the Northern Dvina under atmospheric pollution was studied. Correlations of morphometric parameters of the assimilation apparatus with the distance to the source of emissions and concentrations of pollutants in the air, snow, soil, and heavy metals in needles were revealed.

The influence of PC "Mondi Syktyvkar Timber Industry Complex" on the chemical composition of pine needles was studied. Comparative anаlysis of the mineral composition of pine needles showed that the age dynamics of the concentrations of the majority of elements under investigation for the background region and for the zone affected by emissions have common trends. The total content of chemical elements in bilberry pine forests did not differ over the needle age or over the distance from the pollution source. Examination carried out in 2007 revealed that the total concentration of elements in the one-year needles of pine is higher than that in the needles of older ages. During the period of studies, a decrease in pine needle mineralization was observed under the conditions of pollution in comparison with the background territory. Under the aerotechnogenic emissions of nitrogen and sulfur oxides, carbon compounds, their accumulation in pine needles was not detected (except for the impacted region at 1.3 km).

In the region of the Middle Urals copper smelting plant, in two contrast zones of atmospheric pollution we evaluated the dimensional and reproductive characteristics of the thalli of epiphytic lichen Hypogymnia physodes (L.) Nyl. and determined the concentrations of heavy metals (Cu, Fe, Cd, Zn, Pb) in them. The nonuniformity of populations both over the dimensional and reproductive characteristics and over metal content was demonstrated. The high heterogeneity of subpopulations growing on different photophytes was discovered. It is recommended to optimise data collection by taking the samples from a large number of trees (20-30) with smaller number of thalli (10-20) from one photophyte.

Biomass of epiphytic lichens on Pinus sylvestris varies from 130 to 1090 g. The major biomass is comprised by the lichens of three genera: Bryoria (45 %), Hypogymnia (34 %) and Evernia (12 %). The majority of lichens are located on tree branches (96 %) in the zone of maximal development (at the height of 9-13.5 m) (66 %). The biomass of lichens on tree trunks is insignificant (4 %) and is concentrated by 70 % at the trunk bases.

Basing on the concept of the effect of landscape structure on the water regime of territory and on the space survey data for the basins of rivers on the northern macro-slope of West Sayan, the landscape hydrogeological classification of natural complexes was made and evaluation of their hydrogeological functions was carried out. At the background of general altitudinаl belt regularities, local features of the distribution of water balance characteristics were revealed.

Possibility to construct the growth class scale for Pinus sylvestris on the basis of the data on the course of growth of separate trunks with maximal height was analyzed. Two principles of the classification of tree stands over growth course are discussed: 1) over the parameters of Mitscherlich function - b₁(upper limit), b₂ (slope), b₃(shape), 2) over the inflection of the curve of tree elongation (h_m is the height at the moment of maximal apical growth rate, t_m is the age of achievement of the maximal apical growth rate).

Sexual systems and the associations with several ecological and life history attributes were examined for 977 native angiosperms of subclass Rosidae in Siberia. The majority of angiosperms in Siberia are hermaphrodites (87,7 %, N = 857). The most widespread forms of sexual differentiation are andromonoecy, gynodioecy and dioecy. The rarest forms of sexual differentiation are monoecy, trioecy and androdioecy. Seven of the 34 families are the richest in species with sexual differentiation: Aceraceae, Elaeagnаceae, Haloragaceae, Rhamnаceae, Diрsacaceae, Apiaceae, Geraniaceae.

Ecological evolution of the species of ebracteatae section of Typha L. genus since eozen is proposed. Typha and Engleria (Leonova) Tzvel. sections were formed in different geological periods and in different regions of Eurasia. The bloom of section Typha contacts the Poltava flora, while section Engleria was formed under the severe conditions of Arcto-Tertiary flora of East Siberia. A noticeable role in the ecological evolution of the sections was played by the West Siberian Sea.
Taxonomic variety and the sizes of areas of the investigated sections, with cold snаps outlined in Pliocene, came to the end in Pleistocene with depletion and insularization. The tendency to convergence in the evolution of the sections of Typha genus was outlined in Holocene.

Numerical computations of the electric-arc heating and anode melting were carried out within the framework of the two-dimensional unsteady mathematical model. The influence of the viscous interaction "plasma−melt", surface tension forces, electromagnetic forces, and gravitational convection on the formation of the hydrodynamics of the anode melt was considered.

The exact solution of boundary layer equations for laminar convective torch from point source of heat in fluid with power dependence of density on temperature was found.

On January 30, 2012 Sergey V. Stankus, the prominent scientist working in the area of thermophysics, Doctor of Physics and Mathematics  and  Deputy Director of the Institute of Thermophysics, became 60 years of age.

Processes of carbon dioxide extraction from biogas by means of sorption using the inorganic residue from the integrated processing of organics-containing wastes (IPOW) as a sorbent were studied. Advantages of the IPOW process and sorption method are demonstrated, the kinetics of carbon dioxide adsorption on the inorganic residue from IPOW was investigated. It was established that the sorption on the inorganic residue is comparable in its capacities with adsorption on activated carbon. Approximate estimation of the volumes of adsorbers for IPOW set-up with the productivity of 500 t/y with respect to biogas was made. A complete scheme of the IPOW set-up including the unit of the sorption separation of biogas is presented.

Thermally reversible polymeric gel forming systems based on polymer solutions with the lower critical temperature of dissolution – cellulose ethers – were developed to increase the oil recovery from highly heterogeneous strata. The reversible phase transition solution–gel occurs due to the thermal energy of a stratum or injected heat transfer agent. Temperature and time of gelatinization can be controlled by adding electrolytes and non-electrolytes. Laboratory studies of the gelatinization kinetics, rheological and filtration characteristics in the system cellulose ethers–aqueous phase–oil are presented. Results of experimental-industrial tests of the technologies of oil recovery enhancement involving thermally reversible polymeric gels for limitation of water inflow, increase in stratum coverage degree during flooding and thermal steam formation treatment are presented. Technologies are economically profitable and ecologically safe; the pay-back period is 5–9 months. The products of large-scale industrial production are used as reagents.

Methods for obtaining biodegradable films based on protein-carbohydrate components by varying their content and establishing optimal physical and mechanical characteristics depending on the ratio of protein components were developed. The resulting films possess integral structure, strength and ability to biodegradation under natural environmental conditions. Singularity of the obtained copolymer films consists in the fact that their destruction leads to the formation of ecologically safe products being a mixture of carbohydrates and amino acids.

Data are presented concerning the macro- and microcomponent composition of the salt lakes of the North-West Mongolia. The evaluation of Li, U-238, B, Br, Sr, Rb content was performed for several lakes of the North-West Mongolia. It was demonstrated that the concentration of U-238 in lake waters can reach 1 mg/L, Li – 50 mg/L, Br – 460 mg/L, B – 100 mg/L. By the example of the Shaazgay Nuur Lake we estimated a daily intake of macro- and microcomponents at the expense of water flowing into the Hargayn Gol River. It was demonstrated that the complex processing of hydromineral raw from the lakes of the North-West Mongolia requires for purifying them from uranium.

Effect of presowing seed treatment and leaf-treatment of plants with different doses of sodium selenite on growth processes, photosynthesis characteristics, spring wheat yield and selenium accumulation in wheat under the conditions of selenium-deficient biogeochemical province in Transbaikalia were studied.

The composition of sulphur and nitrogen compounds contained in the bitumenoid isolated from Cambrian rocks oil shale formation was studied. It has been demonstrated that the sulphur compounds contain benzo-, dibenzo-, naphthobenzothiophenes and dibenzothiophene sulphoxides. Nitrogen compounds are presented by weak bases and neutral components. Among the weak bases, there are predominately alkyl homologues of dibenzoquinolone, dibenzothiaquinolone, dibenzoquinolinecarboxylic acids. The maximum in the distribution of neutral nitrogen-containing components corresponds to the alkyl derivatives of benzocarbazole and benzothiophenecarbazole as well as mononaphtheno derivatives of carbazolecarboxylic acids.

Basing on the components of an available naturally occurring renewable raw material, a synthesis of a novel chiral optically pure diamine belonging to diterpene series was realized. The tricyclic trans-1,2-diamine obtained and its derivatives could be used as ligand for metal complex catalysts of asymmetric reactions.

Results are reported concerning a model experiment for studying the physiological characteristics of two plant species, the activity of soil enzymes, the intensity of oil pollution accumulation and oil composition depending on the amount of oil introduced into the permafrost soil. It was suggested that with increasing the intensity of oil pollution, the soil-plant system mechanisms from the antioxidant and DNA repairing systems to apoptosis and SOS reparations. Introducing the same amount of oil into the soil (0.16 %) in the experiments with growing plants without them demonstrated that the action of the soil microflora resulted in the biodegradation of about one-third (32.2 %) of the oil introduced. In the case of plant growth (wormwood and peppergrass) the transformation of oil-caused contamination was much more profound amounting to 60.0 and 66.7 %, respectively. In the presence of the plants the process of destruction, alongside with n-alkanes and 2- and 3-methylalkanes, involve a wide range of structural isomers, including 12- and 13-methylalkanes and isoprenoids. As a result, the hydrocarbon composition of bitumenoids demonstrates changes direction toward restoring the natural geochemical background. The results obtained in studying the adaptive capacity of plants and the pollution transformation efficiency allow one to find out the maximum permissible residual oil contamination level in the soil, which level amounted to 0.1 %, or 1 g/kg of soil.

Studies concerning the liquid-phase catalytic reductive dechlorination of toxic man-made products using catalysts M/Sibunit (M = Ni, Pt, Pd) were performed. It has been demonstrated that the most pronounced activity is exhibited by catalysts based on palladium.

The reaction of catalytic hydrocracking the triglycerides of fatty acids from rapeseed oil with obtaining a mixture of С₁₂–С₁₉ alkanes on Ni–Cu/CeO₂–ZrO₂ catalyst under mild conditions (0.5 MPa Н₂, 300–380 °С) was studied. Basing on the distribution of hydrocracking products at different contact time and temperature values, a scheme is proposed for stepwise hydrocracking the triglycerides of fatty acids that takes into account the formation of oxygen-containing intermediate products (fatty acids, esters, alcohols, and waxes).

Using the method of Fourier transform infrared spectroscopy, a study was performed concerning the composition of surface functional groups inherent in birch activated carbon BAU-A as well as changing their qualitative and quantitative composition in the course of gold sorption from chloride solutions with different composition under the action of ultraviolet irradiation and without it. It has been demonstrated that under the action of UV irradiation the amount of hydroxyl groups on the surface of birch activated carbon exhibits an increase, which results in an increase in its sorption capacity for [AuCl₄]^– anions. The method of EXAFS spectroscopy revealed that after the sorption from hydrochloric acid solutions, gold on the surface of birch activated carbon is in the form of dimers Au₂Cl₆ both after ultraviolet irradiation and without it. The sorption mechanism is suggested to involve the following stages: ion exchange of surface hydroxyl groups for the complex ions [AuCl₄]^– as well as the formation of dimers Au₂Cl₆ on the surface of carbon.

Lead content in woody vegetation at the genetic profile level was investigated at the territory of Irkutsk, a large industrial centre of Eastern Siberia. It was demonstrated that lead income caused by technogenic emissions contributes significantly to the pollution of the urban ecosystem. Lead accumulation in needles and leaves of the woody plants at the urban area can exceed the background levels more than 10 times, maximally up to 25 times. The high level of lead is also revealed in the top humus and humus accumulative horizons. Its active vertical migration into textural illuvial and pedogenic horizons of the soil genetic profile was discovered. It is shown that the redistribution of the labile lead in the soil solution of the organic and mineral horizons is accompanied by its interaction with phosphate and sulphate ions, exchange cations (sodium, potassium, magnesium), and heavy metal ions (zinc, copper, cadmium, manganese). Reliable direct correlations between the content of mobile lead in urban soil and lead concentration in the assimilative organs of woody plants are revealed.

Obtaining dimethyl ether from synthesis gas with the use of a two-layer catalyst was studied. An optimum level-by-level loading was determined for two catalytic systems such as methanol production catalyst Katalco-58 and methanol dehydration catalyst γ-Al₂O₃ It was demonstrated that increasing the temperature and contact time results in increasing the CO conversion level and the yield of dimethyl ether, whereas their maximum values are attained at a pressure of 3 MPa. The optimum process conditions are: Т = 280 °С, Р = 3 MPa, Н₂/СО = 2, the contact time 6 s.

Reactions of (+)-limonene and (-)-β-pinene with hetarenesulphenyl chlorides (2-benzothiazolesulphenyl chloride, 3-methoxycarbonyl-2-pyridylsulphenyl chloride) were studied.

Basing on betulin vinylation by acetylene in superbasic medium KOH/DMSO, mono- and divinyl esters of betulin, valuable monomers and intermediates for the synthesis of polymers and biologically active compounds were obtained.