Vol 487, No 6 (2019)

After the description by E. Cartan in 1932 holomorphically homogeneous real hypersurfaces of two-dimensional complex spaces, a similar study in the 3-dimensional case remains incomplete. In a series of works performed by several international teams of authors, the problem is reduced to describing homogeneous surfaces that are non-degenerate in Levi sense and have exactly 5-dimensional Lie algebras of holomorphic vector fields. In this paper, precisely such homogeneous surfaces are investigated. At the same time, a significant part of the extensive list of abstract 5-dimensional Lie algebras does not provide new examples of homogeneity. A complete description of the orbits of 5-dimensional non-solvable Lie algebras in a three-dimensional complex space, given in the paper, includes examples of new homogeneous hypersurfaces. The presented results bring to finish a large-scale scientific study of interest to various branches of mathematics.

In the paper, a description of the Grothendieck-Serre duality on an arithmetic surface by means of fixing a horizontal divisor is given and this description is applied to the generalization of theta-invariants.

Studies of the interaction of electromagnetic microwaves with [Co₈₈Fe₁₂/Cu]_n, nanostructures, in which the giant magnetoresistive effect (GMR) shows itself, have been carried out. It is established that the GMR effect contributes to changes in the microwave complex refraction coefficient, including the refractive index.

A new 2-amino-4-ferrocenyl-thiophene-3-carbonitrile was synthesized by the Gevald reaction and Schiff bases, precursors for new optoelectronic and magnetic materials, were obtained on its basis. The structures of the synthesized compounds were determined by elemental analysis, IR and ¹H NMR spectroscopy.

Thermal stability and gas phase composition of the most common technical mixtures of polychlorinated biphenyls “Sovol” and “Trichlorobiphenyl” were studied by simultaneous thermal analysis and mass spectrometry compared to their derivatives synthesized by the interaction of these mixtures with sodium methoxide in dimethyl sulfoxide and methanol. For the first time it was established that derivatives of polychlorinated biphenyls are less thermostable compounds as compared with the initial products and under pyrolysis they undergo not only evaporation stages, but also decomposition processes to the simplest volatile substances. Thermal destruction of derivatives is characterized by a decrease in the level of emission of hazardous compounds and requires less energy.

SmFeGe2O7 germanate was obtained by solid-state reactions from stoichiometric mixtures of starting oxides with multistage firing within 1273-1473 K. The effect of temperature on the heat capacity of the compound was studied using differential scanning calorimetry. Based on the dependence C_p = f(T), its thermodynamic properties are calculated.

Paper presents results of isotope studies of primary igneous and sedimentary rocks of Mawson and Menzies series from the southern Prince Charles Mountains, East Antarctica. Obtained data show that igneous protholith crystallization of Mawson orthogneiss occurred at 3164,2±9,2-3163,2±7,8 Ma ago. The Mawson orthogneiss were a basement for Menzies series sediment. The maximum time of sediment deposition is estimated to be in the range of 3,0-3,1 Ga. Sediment protholith involves an admixture of Paleoarchean material.

New U-Pb (SIMS and LA-ICP-MS) geochronological data for rocks of Egdygkych complex of hypabyssal intrusions, Nichan and Vukney plutons, and felsic volcanic rocks and tuffs from host strata of Oloy volcanic belt of Alasey-Oloy fold system are obtained. Concordant ages of Egdygkych complex rocks correspond to Early Cretaceous (Berriasian-Valanginian), those for host strata, to the end of Late Jurassic (Tithonian) - beginning of Early Cretaceous (Berriasian). New U-Pb geochronological data allow confidently to distinguish uniform volcanic-plutonic assemblage of Late Jurassic (Tithonian) - Early Cretaceous (Berriasian-Valanginian) age of Oloy volcanic belt. Obtained data more definitely determine age limits of Au-Mo-Cu mineralization, associated with contacts between rocks of Egdydkych complex and host volcanic-sedimentary rocks or contacts of separated intrusive phases.

The high REE contents (57,23-561,2 ppm) of thin-layered sulfide ores of the Talgan Cu-Zn massive sulfide deposit (South Urals) are related to the presence of REE minerals: galgenbergite, parisite, bastnesite, synchysite and xenotime, which were found for the first time in massive sulfide deposits of the Urals. These minerals occur in quartz-carbonate-chlorite matrix of sulfide layers, as well as pyrite nodules and sub- and euderal crystals. The chondrite-normalized REE patterns are enriched in LREEs relatively to HREEs and the presence of weak negative cerium and positive europium anomalies. The LREE contents decrease by an order of magnitude and the LREE and HREE contents become similar with decreasing amount of hyaloclastic material in sulfide layers. The REEs for the formation of REE minerals are derived from mixed carbonate-hyaloclastic and ore material during the formation of layered sulfide ores.

Quantitative estimates on the ozone production efficiency (OPE) per a molecular of NOx (=NO+NO2), ΔP, and ozone production rate, PQ, are derived for the region of Central Siberia based on near surface observations of O3, NO, and NO2) at Zotino Tall Tower Observatory in 2007-2015. Experimental data follow are a power law dependencies on NOx abundance: P_Q χ [NO_x]^-n+1, ΔP χ [NO_x]^-n, n = 0,82±0,06 (coefficient of determination R2 = 0,66), with the power law exponent corresponding to a NOx-limiting regime of ozone production in a weakly polluted air mass. During summer, the value of ΔP ranges from 30,0-43,7 [mol.O3/mol.NOx] which agrees well with the corresponding estimate of 39,8 [mol.O3/mol.NOx] derived from GEOS‑chem CTM model simulations. The derived estimates provide an observation based conclusion on the important role of regional anthropogenic emissions of NOx in summertime ozone photochemistry in the remote areas of Siberia.

The main aim of the study is to determine stable oxygen and hydrogen isotope composition of Late Pleistocene syngenetic ice wedges of Batagay yedoma and to obtain the detailed isotope diagrams. Reconstructed mean January palaeotemperature is lower than -51 °С than completely confirmed validity of earlier created palaeotemperature maps for the period 30-25 thousand years ago where Batagay section is located within isotherm of -48 °С.

An updated climatology of upper level frontal zones (UFZ) of the Northern Hemisphere is presented, based on a numerical analysis of geopotential gradients and the allocation of maximum gradient zones. Differences in the position of the UFZ during the development of meridional and zonal processes are revealed. Based on the analysis of years with the predominance of various forms of circulation, it is shown that the position of high-altitude frontal zones is an objective diagnostic tool for studying modern climate variability.

There are contradictory views on the contribution of the near-surface layer of bubbles to the attenuation of low-frequency sound in the ocean. Taking into account the new experimental data on the distribution of bubbles in sea water, it is shown that the influence of the near-surface layer of bubbles on the structure of the spatial decay in the propagation of sound can be significant at fairly typical concentrations of bubbles in the near-surface layers of the ocean. A possible explanation for the contradictions is the spatial restructuring of the field structure, in which the main effect of the bubbles is concentrated at the near distance, at the same time not affecting the sound attenuation at the far distance.

It has been studied the result of assembling the light-harvesting complexes in the cells of purple sulfuric bacterium Thiorhodospira (T.) sibirica, strain Kir‑3, while suppressing biosynthesis of carotenoids by diphenylamine (DPA). LH2 complexes (B800-850 and B800-830) with different carotenoids’ composition were isolated from the cells obtained. Maximal inhibition of carotenoid biosynthesis (~90% of the control) was achieved at the inhibitor concentration of 53,25 mM (9 mg/l). It has been established that changes in qualitative and quantitative composition of carotenoids do not affect the assembling of B800-830 and B800-850 complexes. It is assumed that in the population of DPA-LH2 complexes from T. sibirica, strain Kir‑3, both carotenoidless complexes and the complexes, containing one or two carotenoid molecules, can be assembled. These results support a hypothesis that carotenoids are not required for assembling B800-850 and B800-830 complexes.

The spectral structure of the alarm call of ground squirrels was studied. A sexual accent was found in the signal of a small ground squirrel (Spermophilus pygmaeus): in the signal of males, the high-frequency component has a higher peak and maximum frequency than in the signal of females. In the signal of four species of ground squirrels (Sp. pygmaeus, Sp. musicus, Sp. xanthoprymnus, Sp. alaschanicus) biphonation was detected. It is suggested that in the signal of these species of ground squirrels low and high frequency components generate different sources of the vocal tract. Material collected in the field.