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184 results on '"Grabovskii, A. P."'

7. Fluid Migration through Permafrost and the Pool of Greenhouse Gases in Frozen Soils of an Oil and Gas Field

Author

Gleb Kraev, Andrei Belonosov, Alexandra Veremeeva, Vasilii Grabovskii, Sergei Sheshukov, Ivan Shelokhov, and Alexander Smirnov

Subjects
carbon dioxide (CO2), methane (CH4), permafrost, active layer, digital elevation models (DEM), land cover, Science
Abstract

Most methane (CH4) and carbon dioxide (CO2) emissions originate from the biodegradation of organic matter of soils and of degrading permafrost in the Arctic. However, there is limited evidence of the activity of geological sources, and little understanding of the pathways of migration of gaseous fluids through the porous mineral matrix filled with ice. We estimated the effect of geological factors on the winter storage of the greenhouse gases in frozen soils by statistical analysis of the geodatabase, which combined a field gas survey of frozen soils, subsurface sounding, and remote sensing data. Frozen soils stored on average 0.016 g CH4 m−3 and 11.5 g CO2 m−3. Microseeps, recognized by isolated anomalies of helium, had 30% higher CH4 concentrations. Lineaments marking margins of tectonic blocks were estimated to have 300% higher CH4 concentrations. High concentrations of propane and ethane indicated the contribution of diffuse fluid flow from hydrocarbon-bearing beds on 95% of the 130 km2 study area. In addition to the fluid contribution, we estimated an overwintering pool of greenhouse gases in frozen soil for the first time. Being at least 0.01–0.1% of the soil organic matter mass, these gaseous forms of carbon can be critical for the early-summer Arctic ecosystem functioning.

Published
2022
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14. Influence of Water on the Structure and Dielectric Properties of the Microcrystalline and Nano-Cellulose

Author

Kostiantyn M. Kovalov, Olexander M. Alekseev, Maxim M. Lazarenko, Yu F. Zabashta, Yurii E. Grabovskii, and Sergii Yu Tkachov

Subjects
Microcrystalline cellulose, Relaxation, X-ray, Dielectric permittivity, Materials of engineering and construction. Mechanics of materials, TA401-492
Abstract

Abstract Influence of water in the different states on a structure and dielectric properties of microcrystalline cellulose were studied by of X-ray, thermogravimetry, and dielectric spectroscopy. At research of microcrystalline cellulose (MCC) with different content of water, it is shown that the molecules of water are located in the macropores of MCC and in multimolecular hydrated layers. It is shown that at the increase of concentration of water in a hydrated shell, the reorganization of molecules of cellulose in the surface of crystallites takes place, and as a result, their transversal size and crystallinity increase. It is shown that during the concentration of water, more than 13% in a continuous hydrated shell of crystallites appears. Temperature dependences of actual and imaginary parts of complex dielectric permittivity were studied in the interval of temperatures [−180 ÷ 120] °C on frequencies of f = 5, 10, 20, and 50 kHz. A low-temperature relaxation process and high-temperature transition were observed. Low-temperature relaxation process which is related to transition of surface methylol groups of molecules of cellulose conformation from tg to tt is shifted toward low temperatures at the increase of concentration of water in microcrystalline cellulose.

Published
2017
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41. Decomposition Kinetics of 1,1-Dihydroperoxycyclohexane in Some Organic Solvents

Author

Andriyashina, Nadezhda M., Grabovskii, Stanislav A., and Safiullin, Rustam L.

Abstract

Background: 1,1-Bishydroperoxides are used as oxidizing agents, radical initiators, in addition, studies of biological activity show the promise of this area of research. Objective: There are currently no kinetic data on the thermal stability of these peroxides in various solvents. Therefore, we investigated the thermal stability of 1,1-dihydroperoxycyclohexane as the most widely used at present. Methods: The rate constants and activation parameters were measured at the temperature range of 100- 170°C in the presence of 2-naphthol, which inhibits the induced decomposition of the peroxide by free radicals. Peroxide concentration was determined by iodometric method. Results: The rate constants of the reaction with the solvents and of the monomolecular decomposition of the peroxide were determined. Conclusion: The use of DHPC as a radical initiator requires taking into account its reactions with the solvent and/or monomer, in addition to its monomolecular decomposition with the formation of free radicals.

Published
2023
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