Vol 488, No 5 (2019)

In this paper, a new class of degenerate pseudo-differential operators is investigated, with a variable symbol depending on the complex parameter. Pseudodifferential operators are constructed by a special integral transform. Theorems on the composition and boundedness of these operators in special weighted spaces are proved. The behavior of these operators on hyperplanes of degeneration is investigated. The theorems on the commutation of these operators with differentiation operators are established. A adjoint operator is constructed and an analogue of Goring inequality for degenerate pseudodifferential operators is proved.

For abstract integro-differential equations with unbounded operator coefficients in a Hilbert space, we study the well-posed solvability of initial problems and carry out spectral analysis of the operator functions that are symbols of these equations. This allows us to represent the strong solutions of these equations as series in exponentials corresponding to points of the spectrum of operator functions. The equations under study are the abstract form of linear integro-partial differential equations arising in viscoelasticity and several other important applications.

In this work we find new bounds for the independence numbers of distance graphs with vertices in {-1, 0, 1}ⁿ.

The first investigations on the fatigue strength of composite materials were carried out on cyclic tension of plastics reinforced by fiberglass. Since that time, intensive studies of fatigue strength of composite materials were begin. The experimental data obtained for different types of composite materials shown, that the fatigue fracture processes are governed by the accumulation of defects of different nature. The main mechanisms that determine the durability of composites is the kinetics of the damaged state development until the final fracture. At the same time, according to the experimental results, the damage accumulation curve of the total damage is defined by increased function of the time (number of loading cycles) until to the moment of macro fracture. In this paper, based on these studies and the conception of scattered damage and fracture, fatigue strength criterion is formulated. Fatigue criterion coefficients are concretized and damage accumulation curves are plotted, which depends on the number cycles and stress level. The comparison with experimental results on fatigue of glass-reinforced plastics and carbon fiber reinforced plastics is given.

One-pot synthesis and the structure study of a new salt spiropyran of indoline series containing 2H-chromenic vinyl-3H-indolium fragment as a substituent at the position 8′ are described. The structure was confirmed by the method of NMR ¹H and ¹³C spectroscopy, IR and high-resolution mass spectrometry. The single crystals of the compound were investigated by X-ray analysis. The structure was compared with the previously known isostructural analogue [10].

Direct high-speed micro-video records prove the existence of highly overheated zones at the contacts of powder particles during short (~ 1 ms) electric current pulses. The value of overheating can exceed 1600 degrees and lead to the formation of liquid-phase sintering necks, the dimensions of which are well correlated with the size of the overheated zones. The micro-uniformity of the temperature field in the electric pulse heating allow understanding the unusually high consolidation rates of powder materials observed in spark plasma sintering.

The geological section of Bol’shoi Ilek (up to 83 m high), southeast of Western Siberia, represented by Cretaceous and Quaternary systems has been reassessed. Its major part is composed with the Lower Cretaceous deposits of deltic genesis that reached 80 m thickness and characterized the Ilek Formation stratotype. During the screen washing of sand fraction the remains of fishes, lizards, turtles, crocodiloformes, dinosaurs, and mammals, typical for the Barremian - Lower Albian, have been revealed. Mesozoic strata are covered by eolian-deluvial and eluvial Quaternary deposits from 3 to 13,5 m. Three layers with mammoth fauna remains were distinguished there. The middle one is dated by ¹⁴С as ~ 22500 years ago. The observation have revealed that Bolshoi Ilek is a large landslide more than 1 square kilometre area. All of it allowed to compare it with the coeval section of Shestakovo outcrop that also exposes the part of giant landslide, caused by earthquakes more than 9 points by Richter scale, which indicates a powerful seismic event, occurred in the southeast of region at the very end of Pleistocene.

Studies of ⁴⁰Ar and ⁴He mobility in minerals (performed for isotope geochronometry problems) generally assumed that the migration parameters, obtained for the atoms preserved in a mineral, described the mobility of all atoms that were produced in the mineral, including those that were lost in the past. To test this assumption, an analysis of the U-Th-Li-⁴He-³He isotope system in amphiboles, separated from alkaline granites of the Ponoi massif, Kola Peninsula, was performed. The retention of He isotopes was determined, i.e., the ratio of the amount of radiogenic He remaining in a mineral to its amount, which should have been accumulated since the formation (metamorphism) of the mineral. It turned out that 36% of ³He and only 14% of ⁴He were preserved in the mineral. The results of experiments on ³He and ⁴He migration from amphibole grains during their step wise heating in vacuum were successfully approximated by a diffusion model. However, the parameters, obtained during the simulations, did not allow reproducing the above retentions of He isotopes. The mechanisms of ³He and ⁴He migration in the past, which have led to such different retentions, differ from the diffusion mechanism, which adequately describes migration of the atoms remaining in the mineral.

Nikmelnikovite, Ca₁₂Fe²⁺Fe³⁺₃Al₃(SiO₄)₆(OH)₂₀, is a new mineral from the Kovdor massif, Kola peninsula, Russian Federation. It is the first trigonal member of the garnet supergroup. The mineral is named in honor of Academician Nikolay Nikolaevich Melnikov (1938-2018), an outstanding Soviet and Russian mining engineer, long-time (1981-2015) director of the Mining Institute of the Kola Science Center, Russian Academy of Sciences.

The parameters of the concentration distribution of trace elements in the oil fields of oil and gas basins of the world, their physic-chemical properties, as well as the geological and geochemical features of oil formation in these basins were studied. It is shown that the ontogenesis of hydrocarbons associated with deep tectonic transformations (geodynamic factor) controls not only the placement of naphtides in the sedimentary cover, but also the diversity of their metallogenic specialization. The classification of oils of various ontogenesis zones is given in accordance to the degree of their enrichment of mineral elements and their belonging to the vanadium or nickel metallogenic type. The oil, characterized by primary rich concentrations of trace elements of the main zone of oil formation, and oil with initially low concentrations of trace elements in the zones of early generation are presented. The processes of transformation of the composition of oils in the areas of hypergenesis lead to their enrichment, whereas the oil of the catagenesis zone is depleted in trace elements.

Changes of annual and seasonal flow of Volga, Don, Yenisei and Lena are estimated by two methods. One of them is to restore the natural flow of recent decades, during which there were observed its significant anthropogenic changes. For these purposes, we used data on the runoff of rivers (tributaries of the considered rivers and their upper parts), the water regime of which is relatively weakly changed by the anthropogenic impact. Another uses the data of water management statistics. Subsequently, the data on the naturalized river flow were compared with the anthropogenic-modified runoff for this and for the previous base period, when anthropogenic impact can be neglected. It is shown that climatic and anthropogenic factors perform either unidirectionally, increasing or decreasing the flow, or in opposite directions. Moreover, the impact of anthropogenic factors, mainly of reservoirs and water consumption, is of the same scale as the influence of climatic factors, while in many cases exceeds it.

In 2016-2017, for the first time, nearly year-long measurements of the current velocities were carried out below the thermocline at a depth of 100 m and at a depth of 1700 m that was about 100 m above the seabed by using the mooring station in the deep central part of the Black Sea. Analysis of the new data set allowed us to uncover the followings. In the near-bottom layer, the significant flow velocities were recorded, reaching a peak magnitude of 0.13 m/s. Near the frequency of 1·10^-6 Hz, in the transition region of the energy spectrum, the spectral energy of the deep current was close to that observed in the same range in the subthermocline layer of the sea. In the range of balanced geostrophic motions, the energy spectrum had a slope of -2,8 that should be compared to a spectrum slope of -1,8 obtained for current below the thermocline. The regular strong horizontal currents were observed near the local inertial frequency f_I. There was a “blue shift” of the inertial maximum up to 5% with respect to f_I in the energy spectrum.

Plasminogen being a precursor of plasmin, a serine protease which plays a fundamental role in the intravascular thrombolysis. For the first time, by using high-resolution mass spectrometry, data were obtained of oxidative modifications of the plasminogen molecule under induced oxidation. The FTIR data show that under oxidation on the protein, its secondary structure also undergoes the rearrangements. The high tolerance of plasminogen to oxidation can be due to both the closed conformation and the ability of some Met residues to serve as ROS trap.

The antioxidant and antiradical properties of the tetra nitrosyl iron complex with thiosulfate ligands (TNIC) in the mouse brain homogenates in vitro were also studied. It was found for the first time that TNIC is an effective antioxidant. The effect of TNIC on the catalytic activity of mitochondrial enzymes: cytochrome c oxidase and monoamine oxidase A has been studied. It was shown for the first time that TNIC is an inhibitor of the catalytic activity of cytochrome c oxidase and monoamine oxidase A in the brain mitochondria isolated from animals in vitro.

For the first time, the analysis of the mandible shape in semispecies of common vole (Microtus arvalis) from the hybrid zone was carried out using geometric morphometry methods. High morphological variability of hybrids that were closer to the parent form Microtus obscurus than to M. arvalis was found. The main trends in the shape of the mandible, which locate mainly in the horizontal plane, are revealed.