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Analysis of long-term fishing and biological data has made it possible to determine the proportion of respawning individuals (the “remainder”) in populations of Atlantic salmon Salmo salar inhabiting large rivers of the Kola Peninsula. The contribution of respawning individuals to the dynamics of the Atlantic salmon population was assessed using the mathematical simulation model. It is shown that the model population becomes more resistant to fishing with increase in the “remainder” proportion; however, the influence of such individuals on the population dynamics is noticeable only when their relative number is more than 5% in the spawning population. The results of different model experiments are interpreted. The role of respawning salmons may be determined not so much by their quantitative contribution to the reproduction process as by the maintenance of the genetic diversity of the population within the reproductive strategy characteristic of the Atlantic salmon.

Developing of laboratories on a chip or μTAS (micro-total analysis systems) is a great challenge of the modern microfluidics. With the help of such devices, it will be possible to conduct many chemical analyses of human liquids for the preliminary diagnosis of various diseases. Despite the great importance of this task and certain successes in the field of experimental study of the behavior of the electrolyte in micro-devices, there are many undescribed effects, which opens up the possibility for a theoretical study of these processes. Usually, the flat geometry of devices is used in design of laboratories on a chip, which is explained by the simplicity of manufacturing, but our research shows that using the spherical geometry of the device allows to design a universal device that can work as a micro-pump, micromixer and micro-concentrator. The paper presents a theoretical analysis of the concentration effects of ions in a micro-device with presence of the pressure driven flow. The device presents a spherical chamber in the center of which an ion-selective microgranule is placed. This device is built into a circular channel through which the electrolyte flows due to the electroosmotic flow caused by the difference in electrical potentials. Depending on the orientation of the inlet channel relative to gravity, there is an additional pressure of the water column in the inlet or outlet channel. As a result of selection of a suitable external electric field, it is possible to achieve a significant concentration of ions near the ion-selective microgranule. The enriched region can be carried away by the convective flow far into the outlet channel and then this device can be used to separate the flow into enriched and depleted, as happens with electrodialysis. The efficiency of the device increases with an increase in the intensity of the external field, however, starting from a certain critical value of the electric field strength, the steady state flow loses stability and an electroconvection is formed, which interferes with the concentration process. Due to the additional pressure, both the stability of the flow and the degree of concentration can be adjusted. The paper shows that by varying the values of the field strength and pressure gradient, it is possible to achieve maximum efficiency of the device.

The method for the synthesis of N-isopropyl-N′,N′-diorganyl-N-[(triethoxysilyl)-methyl]ureas was optimized. The reaction of these compounds with triethanolamine afforded the corresponding N-(silatranylmethyl)ureas R2NC(O)N(Pri)CH2Si(OCH2CH2)3N (R = Me, Ph). The structures of the new compounds were confirmed by multinuclear NMR spectroscopy. The structure of the silane Ph2NC(O)N(Pri)CH2Si(OEt)3 was established by X-ray diffraction. Preliminary data on the effect of N-isopropyl-N′,N′-dimethyl-N-(silatranylmethyl)urea on the parameters of the rapeseed and wheat growth were obtained.

In the Kola River (Kola Peninsula), on the basis of cluster analysis of long-term density data in the nursery areas of underyearlings, wild and wild + hatchery parr of Atlantic salmon Salmo salar L., four clusters have been identified in each group of juveniles with high, medium, low, and very low density. In the lower and upper reaches of the river, areas were identified where the state of salmon reproduction can be assessed as critical. The article discusses the role of illegal, unreported, unregulated fishing, ulcerative dermal necrosis and hatchery reproduction as possible reasons for the decline in the reproductive potential of one of the most significant salmon rivers in the region.

Numerical modeling of the outflow of an air jet into water with a guillotine rupture of a pipeline by the VOF method using k-ε and k-ω SST turbulence models was carried out. The calculations were carried out in the axisymmetric approximation. The following phases of the outflow process were calculated: the formation of a large gas bubble at the place of the rupture, its growth, the separation of the bubble from the place of rupture, and the formation of a gas jet behind the bubble. It is shown that the rate of bubble detachment in the calculations by the k-ω SST model is higher than that in the calculation by the k-ε model.

Gas outflow into a cavity with different annular assembly filled with liquid by the VOF method, supplemented by the k-ε turbulence model, is numerically simulated. Calculations are performed for three types of ring assembly. Principal scenarios of bubble growth outside the assembly and annular jets inside it are obtained. The characteristic expiration times are investigated.

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.

The results of a comparative analysis of the efficiency of the artificial reproduction of Atlantic salmon ( Salmo salar ) individuals released to the Kola River at ages of 3 years (1980–2002) and 1 year (2003–2017) are given. After the fish hatcheries began to release artificially reared anadromous salmon individuals at the age of 1 year, their qualitative parameters did not significantly change. The value of the commercial return became somewhat lower for the released yearlings than for the 3-year-old individuals; however, it remained satisfactorily high. It is recommended to reduce the release volume to avoid the overpopulation of juveniles; it is also suggested to evenly distribute them over the nursery grounds that are most suitable for their adaptation and select spawners for broodstock according to the historically established subpopulation structure.

Quantum chemical calculations of (O—Si)-chelate N -(fluorosilyl)methyl- N -isopropyl- N ′, N ′-dimethyl- and N -(fluorosilyl)methyl- N -isopropyl- N ′, N ′-diphenylureas by DFT in the gas phase and in a polar DMSO medium showed the dependence of the geometric parameters of their molecules on the stereoelectronic effects of substituents at the silicon and nitrogen atoms and the polarity of the medium. The nature of the Si—O and Si—F bonds of the axial fragment of the coordination site was determined using the analysis of the topological characteristics of the bond critical points and the determination of their energy values within the framework of the quantum theory of atoms in molecules (QTAIM); NBO analysis (NBO is natural bond orbital) of orbital interactions of the LEP of the N and O atoms and the vacant orbitals of the C=O and C—N bonds showed their dependence on the polarity of the medium. A comparison of the experimental and calculated IR spectra of the studied compounds in the solid state and polar medium indicates an inversion of the v as frequencies characterizing the vibrations of the O=C—N(1) carbonyl group and the N(1)—C—N(2) fragment in N -(trifluorosilyl)methyl- N -isopropyl- N ′, N ′-dimethylurea.

The simulation of air injection into a liquid (water, liquid lead) at large pressure drops (ΔP = 160 × 105 Pa) has been carried out. A significant difference in the formation of the air volume during injection into water and liquid lead is demonstrated. The shape of the resulting air volume formed during injection into liquid lead is shown to depend on the nozzle diameter. It is established that the presence of interfacial heat transfer at short times does not affect the dynamics of the air jet outflow.