Home – Home – Jornals – Chemistry for Sustainable Development 2023 number 6

Radiometric dating of zircon grains from crustal xenoliths in kimberlites of the Yakutian diamond province show that most of the Daldyn and Markha terranes were formed in Paleoarchean but preserve some fragments of Eaoachean and possibly even Hadean crust recycled in several tectonothermal events. The oldest zircons were crystallized about 3.2 Ga and recrystallized during later activity stages of 2.9, 2.8-2.7, and 1.9 Ga, whereby they gained radiogenic hafnium produced by ¹⁷⁶Lu decay in the rock. The degrees crust rework and the tectonothermal stages varied across the Anabar tectonic province. The earliest events of 3.2 and 2.9 Ga left record in zircons from kimberlites in the Nakyn field, while the signatures of the 2.7 Ga activity are best pronounced in zircons from kimberlites sampled in the Upper Muna and Nakyn fields. On the other hand, zircons from lower crustal mafic granulite xenoliths in the Daldyn and Alakit-Markha kimberlites lack traces of the earliest crust history and only evidence of the last 1.9 Ga event, which remained mute in xenolith samples from the Upper Muna field. Zircons from felsic granulite and metadiorite xenoliths in the Udachnaya kimberlite, which represent middle and upper crust, show a peak at 2.6 Ga besides that of 1.9 Ga. The synthesized available data support several previous inferences: vertical and lateral heterogeneity of the crust in the Yakutian diamond province; absence of linkage between the crust recycling degree and major collisional zones of the Siberian craton; absence of the separate Markha terrane. Correlation of age peaks corresponding to thermal events in the crust history of the Anabar tectonic province with those of large igneous provinces allows a hypothesis that the revealed tectonothermal events may be related with the activity of superplumes.

The Early Devonian Altai-Sayan rift system (ASRS) has spread to the structures of East and West Sayan, Kuznetsk Alatau, and Mongolian Altay. Its largest fragments are the Tuva, Delyun-Yustyd, Kan, Agul, and Minusa basins as well as depressions in northwestern Mongolia. The paper summarizes the geologic, geochemical, and Sr-Nd isotope characteristics of the ASRS mafic rocks represented by nappes of moderately alkaline and alkali basalts and their subvolcanic and intrusive rock analogues. They are present in all magmatic associations and are divided into low-Ti (TiO₂ = 0.2-2.2 wt.%) and high-Ti (TiO₂ = 2.2-4.3 wt.%) subgroups. These rocks are characterized by wide variations in Sr isotope characteristics (ε_Sr(T) = -16 to +30). High-Ti mafic rocks are common at the southern segment of the ASRS; they show a weak positive Ta-Nb anomaly (La/Nb = 0.8-1.1) and are relatively enriched in LREE ((La/Yb)_N = 6-14) and radiogenic Nd (ε_Nd(T) = 3.8-8.7). Low-Ti varieties are confined to the northwestern segment of the ASRS; they are enriched in Ba but depleted in Th, U, Nb, Ta (La/Nb = 1.2-2.2), Zr, Hf, LREE ((La/Yb)_N = 3-7), and radiogenic Nd (ε_Nd(T) = 2.0-6.0). Taking into account the existence of different terranes, which were combined in the structure of the Altai-Sayan folded area during accretion (ca. 500-480 Ma), we propose a model suggesting different environments of magma formation at the southern and northwestern segments of the ASRS and the relationship of magmatism with a mantle plume within the ASRS. In composition the plume corresponds to the sources of high-Ti magmas. The effect of the melted lithospheric mantle of different compositions beneath different groups of terranes led to the observed isotope-geochemical heterogeneity of mafic rocks within the ASRS, in particular, the absence of high-Ti mafic rocks from the Minusa basin.

Rock samples from the Khamaryn-Khural-Khiid combustion metamorphic (CM) complex, including cristobalite clinker, ferroan tridymite-sekaninaite and cristobalite-fayalite paralavas, which are rock types new to the complex, as well as clinker xenoliths in melilite-nepheline paralava, have been studied in terms of chemistry and mineralogy. The obtained data on rock-forming, minor, accessory, and rare phases (silica polymorphs, cordierite-group minerals, fayalite, Fe and Ti oxides, ferrosilite, etc.) have implications for the formation conditions and processes of the CM rocks. The Raman spectra of sekaninaite, indialite, ferroindialite, mullite, and anhydrous Fe-Ca-Mn phosphate, presumably from the graftonite group, have several specific features. The diversity of mineral assemblages in the CM rocks is due to heterogeneous lithology of the sedimentary protolith and to local effects in the multistage history of the Khamaryn-Khural-Khiid complex. According to geochemical data, all CM rocks of the complex are derived from the Early Cretaceous Dzunbain Formation, their protolith molten to different degrees. The cristobalite clinker and tridymite-sekaninaite and cristobalite-fayalite paralavas were produced by partial melting of pelitic rocks containing different amounts of iron in a wide temperature range. The formation of mullite developed from dehydration-dehydroxylation and incongruent partial melting of amorphous pelitic matter. Large-scale crystallization of mullite in clinker, occurred from the high-silica potassic aluminosilicate melt at >850 °C. Combustion of subsurface coal seams heated the overburden to >1050 °C or locally to >1300-1400 °C (melting point of detrital quartz) or even, possibly, to >1470 °C corresponding to the stability field of β-cristobalite. Melilite-nepheline paralava was formed by incongruent melting of silicate (pelitic) and carbonate (calcite) components of marly limestone under elevated CO₂ partial pressure. Oxygen fugacity ( ƒ _O2) during combustion metamorphism changed from strongly reducing conditions favorable for crystallization of Fe phosphides (barringerite, schreibersite) and metallic iron from silica-undersaturated melts parental to melilite-nepheline paralava to high ƒ _O2 values that can maintain the formation of hematite in Fe-rich CM rocks.

The geochemical and mineralogical aspects of the distribution of rare-earth elements (REE) in ferruginous deposits (FD) and bottom sediments of the southeastern Laptev Sea are analyzed. The FD are dominated by biomorphs developed after polychaete tubes. The REE patterns depend on the proportion of ore and non-ore substances. The ore substance is represented mainly by iron hydroxides (limonite). It is a product of suboxic diagenesis enhanced by bioturbation and determines the slight enrichment of FD in MREE and cerium deficiency (Ce_an = 0.94). The non-ore substance comes from terrigenous sediments and has an (alumino)silicate composition. It controls the scandium content and is the source of REE mineral grains, among which monazite-(Ce) prevails. The sediments demonstrate a common similarity in REE patterns to shales and suspended material transported to the Laptev Sea by the Lena River, with elevated LREE and MREE contents and the value of Ce anomaly almost equal to unity (Ce_an = 1.06). In the sediments, REE minerals occur mostly in the silt fraction (<63 μm in size). The high content of organic matter (C_org of up to 2.15%) of predominantly terrigenous origin (OM_ter of up to 85%) in the sediments explains the oxygen deficiency and weak diagenetic mineral formation with low accumulation of trace elements, including REE, in the FD. The total REE content in the FD is lower than that in the sediments (on average, 173 ppm against 206 ppm).

The Bazhenov Formation of the Western Siberian oil-and-gas province is currently one of the key objects of potential growth in oil reserves and production. Here we present results of a geochemical study of the Bazhenov Formation according to the methodology developed at Trofimuk Institute of Petroleum Geology and Geophysics, Novosibirsk (IPGG SB RAS) for rocks highly enriched in organic matter. The features of the group and hydrocarbon compositions of the bitumoids that are filling open and closed pores of the Bazhenov Formation rocks from the North-Surgut region were considered. It has been established that most of the naphthides are in a free (phase-segregated) or sorbed state in a closed pore space. The open pores contain the most mobile components of bitumoids, redistributed from closed pores during the primary migration and remained after the secondary migration of naphtides from the Bazhenov Formation to the Berriasian-lower Aptian reservoirs (A and B strata groups). The methodology used in this work allows determining intervals with increased open porosity and oil saturation in the section of the Bazhenov Formation (silicites and carbonates) by the volume of pore space occupied by open-pore bitumoids.

The Bachat earthquake ( M = 6.1) with the epicenter coordinates of 54.29° N, 86.17° E occurred on June, 18 2013 near the Bachatsky coal strip mine, is the world’s largest earthquake induced while mining solid minerals. More than 5000 aftershocks were registered and the spatial volumetric structure of the aftershock area was investigated. The Bachat coal field is located in the Salair zone of the Kuznetsk Depression and is represented by a brachysynclinal fold of a very complex structure characterized by the damage and fracturing behaviors of rocks. The main event is confined to the coal-mine pit wall, with the greatest density of aftershocks observed in its middle portion. In the cross section, aftershocks form a wide area with its deepened portion shifted towards the Kuznetsk Depression, while large faults bounding the depression dip down under the Salair Ridge. In the exposed pit wall, at a depth of 4 km, the activated area resembles a rhombus whose horizontal diagonal line runs across the entire length of the mine pit and decreases both in upward and downward directions. The area is seismically activated to a depth of 6 km, with more intense activation of rock mass observed within the 1-3 km depth interval. Results of the study of the mechanisms of aftershock sources revealed a disagreement between the stress state of rock mass of the Bachatsky open-pit coal mine modeled from the mechanisms of aftershocks, and the mainshock mechanism of the Bachat earthquake.

The paper presents data on the contents of major and trace elements in garnet xenocrysts from kimberlites of the highly diamondiferous V. Grib pipe (1100 grains) and weakly diamondiferous TsNIGRI-Arkhangelskaya pipe (446 grains). We have established that the high diamond potential of the V. Grib kimberlite pipe is due to several factors related to the composition and structure of the lithospheric mantle represented by kimberlite: (1) a “cold” regime, with a heat flow of 36-38 mW/m²; (2) a thick “diamond window” (70-102 km), with the depth level of the lower boundary of the lithospheric mantle estimated at >200 km; (3) the high degree of preservation of diamond-bearing peridotites under the P-T conditions of diamond stability despite the high degree of impregnation of the lithospheric-mantle rocks by high-temperature silicate melts. The low diamond content of the TsNIGRI-Arkhangelskaya kimberlite pipe as compared with the V. Grib pipe is due to the following factors: (1) a more intense heat flow in the lithospheric mantle, 38-42 mW/m²; (2) a thinner “diamond window”, 10-60 km, with the depth level of the lower boundary of the lithospheric mantle estimated at <200 km; (3) weak impregnation of the rocks of the middle and lower lithospheric mantle by CHO fluid/melt, which might have induced diamond formation; (4) minimum preservation of diamond-bearing peridotites in the lower lithospheric mantle, partly because of the possible impregnation of this zone by high-temperature silicate melts.

The digital elevation model (SRTM03) of the central part of the Lower Amur province is analyzed. The Limuri-Amgun ring structure is identified on the basis of a set of features, and it is also the location of the Pilda-Limuri and Kherpuchin-V’yunsky gold-ore regions, as well as the Albazino deposit, known for large industrial gold deposits and many small deposits and ore occurrences. The distribution of linear and ring elements of the relief is analyzed and geologically interpreted, and its spatial relationship with gold deposits and ore occurrences is shown. The relationship between the morphological severity of the ring structure and the deep structure of the region is shown. It is revealed that the structure is magmatic and characterized by a high concentration of intrusive bodies. According to the reference data on the age and composition of the igneous complexes of the region, the formation of the ring structure is associated with the processes of neoformation and transformation of the Earth’s crust and upper mantle during the end of the Late Cretaceous and the beginning of the Paleocene in a suprasubduction geodynamic setting.

The polar vortices play a significant role in the distribution of stratospheric ozone, the movement of air masses in the polar and subpolar stratosphere, and temperature changes over the polar region. The Antarctic polar vortex forms in autumn and reaches its peak intensity in early spring. In late spring, when this vortex weakens, the influence of the lower subtropical stratosphere increases. We consider the effect of temperature changes in the lower subtropical stratosphere on the Antarctic polar vortex strengthening. Using correlation analysis and ARA5 reanalysis data, we show a significant increase in the effect of minor temperature changes in the lower subtropical stratosphere on the Antarctic polar vortex dynamics in the second half of November.

This work continues the series of experimental studies of fluctuations of the parameters of optical waves along extended paths. In this part, we study possibilities of using an adaptive optics system for focusing laser radiation along long paths in the atmosphere. The adaptive optics system is described, which is part of a hybrid system that provides focusing of a laser radiation beam along an extended atmospheric path. A focusing system, which uses a Shack-Hartmann wavefront sensor, a deformable controllable mirror, and a wavefront tilt corrector implements a phase conjugation algorithm based on a signal from a point reference source. To accompany the experiment, optical and acoustic meters of the level of turbulence and wind speed were used. The results show both opportunities and limitations for the efficient operation of the system on a long turbulent path.

An original technique for pumping a pulsed CO₂ laser with a longitudinal discharge in an alternating magnetic field is proposed and implemented. Based on this technique proposed technique, a small CO₂ laser with an active medium length of ~ 200 mm, a pulse energy of ~ 30 mJ, and an efficiency of 3.4% is designed. It is revealed that the main factor which limits the generation energy of small lasers is the development of current instabilities in a longitudinal discharge across a cross section of the discharge tube. It is noted that the growth of instabilities accelerates with increasing pressure of a CO₂ : N₂ : H₂ : He gas mixture to more than 0.1 atm and the specific pump power to more than 3 MW/cm³. The use of an external alternating magnetic field superimposed on a pulsed longitudinal discharge makes it possible to increase the total pressure of the gas mixture in the laser to 0.4 atm while maintaining the combustion of the volume discharge.

The physical processes of crystallization of melt droplets in water have been studied using the droplet granulation and melt centrifugation methods. A mathematical model has been developed that makes it possible to determine the cooling and crystallization rates and dendritic structural parameter of aluminum alloy granules from the initial data of the process, the diameter of melt droplets, and cooling conditions. Predicting the dendritic parameter of the microstructure of granules allows one to predict the level of microstructure dispersion and hence the strength properties of the granulate material. The model parameters take into account the speed of droplet motion, features of heat removal processes, and the temperature dependence of the thermophysical parameters of the media. An application program implementing the developed mathematical model has been developed. Implementation of the developed mathematical model has been carried out using the Microsoft Visual C++ programming language. The mathematical model has been tested in the granulation of highly alloyed aluminum alloys (D1 and D16 alloys of the Al-Cu-Mg system, and B95 and B96Ts alloys of the Al-Zn-Mg-Cu system) obtained by centrifugal melt spraying and the droplet methods with cooling in water. Crystallization rate in full-scale samples has been measured based on an analysis of the dendritic structural parameter of the material. Analysis of the calculated values of the dendritic parameter and its measurements for real granule samples has shown that there is good agreement between the simulation and measurement results.

The deposition of a nickel-based cermet coating containing 60 % tungsten carbide has been studied. The effect of substrate preheating up to 500 °С on the intensity of the in-situ synthesis of secondary ceramic particles obtained by dissolving the initial particles in a metallic matrix has been investigated. It has been shown that preheating contributes to the prevention of cracks and pores in the coating. Using synchrotron radiation, it has been found that additional heating of the sample during surfacing to a temperature of 500 °С does not cause significant changes in the phase composition of the resulting composite.

The influence of substrate preheating on the structure of a cermet-coating obtained by direct metal deposition from Ti64 alloy reinforced with B₄C particles. Coatings containing 15 %. B₄C were obtained for the first time. It has been shown that the use of substrate preheating makes it possible to produce cermet coatings without cracks. It has been found that in tribological tests, that the scratch volume of the cermet coating decreases by a factor of eight compared to the coating with the content of B₄C 10 %.

Results on a nanoparticle collision with a target calculated by the molecular dynamics method are presented. The first problem being solved is a nanoparticle collision with a target under the conditions of cold gas-dynamic spraying. The second problem deals with nanoparticle extension, which adheres to the target due to the collision. It is shown that a chemical bond between the nanoparticle and target due to the collision. The bond in the case of titanium nanoparticle impingement onto an aluminum target is found to be stronger than that in the case of aluminum nanoparticle impingement onto a titanium target. The reason is that the titanium nanoparticle penetrates into the aluminum target to a greater depth.

The centrally symmetric problem of determining the velocity field in a continuous elastoplastic medium under a camouflage explosion has been solved using the assumptions of the unoscillatory nature of the motion and the incompressibility of the medium in the regions of plasticity and elasticity. The solution was found using a camouflage equation-the relation for determining the pressure on the contact surface of an expanding explosion cavity. The solution allows one to estimate the dimensions of the expansion and plastic deformation regions and the impact of explosive disturbances on objects

A nitrogen jet expanding during its exhaustion from a nozzle into a vacuum chamber is numerically simulated by a hybrid approach. The flow parameters in the nozzle and in the near field of the jet are determined by solving the Navier-Stokes equations by using the ANSYS Fluent software. The gas flow at large distances from the nozzle exit is modeled by the Direct Simulation Monte Carlo method by using the SMILE software system. Such an approach makes it possible to perform sufficiently accurate simulations in the near field of the jet; moreover, the temperature nonequilibrium of the expanding gas jet and other effects of rarefaction in the far field of the jet are taken into account. The approach is verified by using various approximate analytical models of gas exhaustion into vacuum. A comparison of the numerical results with available experimental data shows that they are in good agreement.

The flow in a far plane momentumless turbulent wake is described using a mathematical model obtained from the algebraic Rodi model of Reynolds stresses. The model is similar to the two-parameter ( k ̶ ε ) turbulence model in the far-wake approximation with a modified empirical constant in the diffusion terms of the equations. A group-theoretical analysis of the mathematical model of the wake was carried out and and a self-similar reduction of the equations of models to a system of ordinary differential equations was performed. An approximate solution of the corresponding boundary value problem is constructed using an asymptotic expansion of the solution in the neighborhood of the singular point.

A passive method for reducing the drag of cylinder by installing a flat plate behind it at a Reynolds number Re=10⁵ has been studied. The paper presents the results of an ANSYS Fluent simulation of the flow around the cylinder-plate system, including the velocity and pressure fields, streamlines, and the dependences of the drag coefficient and the position of the separation point on the surface of the cylinder on the relative length of the plate. It has been found that the drag coefficient of the cylinder-plate system can be reduced by approximately 40% compared to the case of an isolated cylinder.

The full Navier-Stokes equations are used to study the linear stability of plane Poiseuille flow in a channel with the lower wall corrugated along the flow, due to which the flow has two velocity components. The generalized eigenvalue problem is solved numerically. Three types of disturbances are considered: flat periodic (the Floquet parameter is zero), flat doubly periodic (finite values of the Floquet parameter), and spatial. Neutral curves are analyzed in a wide range of the corrugation parameter and Reynolds number. It is found that the critical Reynolds number above which disturbances that increase over time appear depends in a complex way on the dimensionless amplitude and period of corrugation. It is shown that in the case of flow in a channel with corrugated wall, three-dimensional disturbances are usually more dangerous. The exception is the small amplitude of corrugation, at which plane disturbances are more dangerous.

This paper presents the results of a statistical analysis of the turbulent structure in a free bubbly jet at a Reynolds number of 12500 based on PIV measurements of the carrier-phase velocity. The distributions of higher-order statistical moments for velocity fluctuations (skewness and excess coefficients) and the energy spectra of turbulence for single-phase and gas-saturated jets were obtained after applying the procedure of statistical filtering to instantaneous velocity fields. The influence of the dispersed phase (bubbles with an average diameter of 0.8 mm) with a volume gas fraction of 0, 1, 2, and 3% for the specified characteristics of the continuous phase was analyzed.

A description of a small climatic wind tunnel designed for studying the icing processes at the Khristianovich Institute of Theoretical and Applied Mechanics of the Siberian Branch of the Russian Academy of Sciences is presented, The use of such a wind tunnel offers a possibility not only of studying the physics of the icing process, but also of testing methods of anti-icing control, validating numerical methods used for calculating the icing processes, etc.

The longitudinal structures generated by external vortical and thermal waves in subsonic and supersonic boundary layers have been studied. Particular attention is paid to setting boundary conditions on the external boundary of the boundary layer. It has been found that disturbances of the longitudinal velocities inside the boundary layer can be several times higher than the amplitude of the external vortical wave. The generation efficiency decreases with increasing Mach number. It has been shown that the influence of thermal external waves on the flow structure in the boundary layer is much weaker than the influence of the vortex structure of the flow

The influence of various physical mechanisms at the stage of collapse of a vapor bubble and the subsequent formation of a cumulative jet in the process of laser-induced boiling near the end of a thin waveguide immersed in a cold liquid is studied numerically. Depending on the intensity of evaporation, three process modes are identified and described.

Three-dimensional numerical simulations of the air flow in the full human bronchial tree in situations of obstructive and chronical pulmonary diseases are performed. Based on the previously developed three-dimensional analytical model of the lower respiratory airways, the air distributions in the lungs (from the trachea to alveoli) in situations with lung injuries and bronchial asthma are calculated. Breathing modeling is based on a numerical technique of stage-by-stage computations, which allows one to avoid the loss of solution accuracy caused by the difference in the bronchus scales; moreover, the time needed to calculate the air flow in the lungs can be reduced by several times by using this technique.

The results of numerical simulation within the framework of a two-dimensional shallow water model of the interaction of a solitary wave with a stationary semi-submerged body with a rectangular cross section are presented. A comparison of these results with the results of calculations based on a model of irrotational three-dimensional flows showed that for small amplitudes of the incident wave, the modeling accuracy is satisfactory. It has been established that neglecting the diffraction of a solitary wave on the surface of a cylinder when using a one-dimensional model of shallow water leads to overestimates of the maximum values of the wave runup on the edge of the cylinder and the force loads on it.

A high-velocity flow in an axisymmetric nozzle containing a central body and pylons is studied. The influence of the geometry of the main and additional pylons on the gas-dynamic and thrust characteristics at the nozzle exit in the flow regime with n_pr= 2.25 ( n_pr is the ratio of the pressure in the settling chamber to the ambient pressure) is determined. Azimuthal nonuniformity of the flow at the nozzle exit is detected. The maximum azimuthal nonuniformity is observed in the wake behind the pylons. It is shown that a three-dimensional transonic flow is formed in the nozzle duct with the pylons mounted in the minimum free-area cross section; local supersonic regions closed by weak shock waves are formed in this flow. It is found that the formation of such a shock wave structure is responsible for nozzle thrust reduction by 12%.

Approximations of the profiles of the longitudinal and transverse velocity components in the boundary layer calculated for the flows around a swept wing and a body of revolution by means of solving the full Navier-Stokes equations and using the boundary layer profiles from the self-similar one-parameter family of the Falkner-Skan-Cooke profiles and two-parameter family of profiles proposed by Gaster are compared. A significant advantage of using the approximation of the numerical profiles near three-dimensional separation by profiles from the two-parameter family is demonstrated.

The process of occurrence of an internal crack of a mixed type (I and II fracture modes) in the wall of a pipe made of an ideal elastoplastic material under the action of combined tensile (compression) and bending loads has been studied. The process of destruction of such materials is described using a modified Leonov-Panasyuk-Dugdale model, which uses an additional parameter - the diameter of the plastic zone (prefracture zone width). The case of complex loading is considered, when the crack trajectory is necessarily curved, therefore the angle of the trajectory break is determined using a force integral criterion based on the asymptotics of the stress field in the vicinity of the crack tip. To obtain critical fracture parameters, a two-parameter (dual) strength criterion is proposed in the case of a complex stress state. An analysis of the parameters included in the resulting analytical model was carried out. The dimensionless geometric parameters of the structure are found numerically using the finite element method. Diagrams of quasi-brittle fracture have been constructed.

The deformation of an ideal elastoplastic adhesive layer of a sample in the form of an elastic double-cantilever beam is considered. Taking into account all diagonal components of the stress tensor in the layer, the values of the J -integral were found for a number of adhesives. It is shown that when using an elastoplastic model of layer deformation, the type of plane problem can have a significant impact on the value of the J -integral. It has been shown that during normal tearing in the zone of irreversible deformation of the adhesive in a plane stressed state, the presence of compressive stresses is possible.

Using the molecular dynamics method, the rigidity constants of five structural configurations of grapheme-carbon monolayer in which the atoms are arranged in a special way and have sp - and sp²-hybritization were calculated. It has been established that the arrangement of atoms in the graphene layer has a significant effect on the stiffness constants. It was found that the γ₂-carafe has the highest stiffness constant c₁₁ (1091 GPa), and the α-carafe has the smallest (258 GPa). It is shown that the β₃-carafe and γ₂-carafe are highly anisotropic structures.

A linear theory of static cylindrical bending of a thin plate is constructed without using Kirchhoff's hypotheses. The transverse shear, thickness compression and the resulting longitudinal force are taken into account. Taking into account the change in the areas of both surfaces during bending, the transverse distributed force is determined. It is assumed that the average pressure on the plate is several orders of magnitude greater than the pressure drop. Bending under conditions of plane deformed and stressed states is considered.

An experimental technique has been developed that allows one to visualize the occurrence and spread of damage in each layer of transparent armor. The dynamics of damage development in multilayer packages consisting of four and eight layers with an area of 480´480 mm and 300´300 mm, respectively, have been analyzed. The evolution of damage was obtained under the influence of a 12.7 mm caliber bullet with a two-component core with a total mass of 59.2 g and a 7.62 mm caliber bullet with a two-component core with a total mass of 10.9 g, both normal and at an acute angle in the range of impact speeds 777÷797 m/s. The experimental data are compared with the results of numerical modeling of the interaction of the striker with a multilayer transparent barrier.

A method has been developed for predicting creep and long-term strength based on data on the behavior of a previously tested sample (leader sample, prototype) under ductile fracture conditions. It is assumed that the material, when loaded, does not have instantaneous plastic deformation and the first stage of creep, and the incompressibility hypothesis is satisfied for it. It is shown that if for a leader sample the creep curve at constant stress and the time until its failure are known, then to obtain a diagram of the rheological deformation and long-term strength of the material at other stress values it is enough to know only the initial (at the initial moment of time) minimum creep strain rate of the samples for these voltage values. The adequacy of the developed method was checked with experimental data during tension of samples made of corrosion-resistant steel grade 12X18H10T at a temperature of 850 °С and samples from a titanium alloy at a temperature of 600 °С, as well as during tension and torsion of samples from the D16T alloy at a temperature of 250 °С. It is shown that the prediction results do not depend on the choice of the leader sample from a number of samples tested at different voltages. The possibility of using the developed method in conducting experimental studies of materials under conditions of creep up to their destruction is discussed.

An original numerical framework is developed in the present research work in order to estimate the free field sound radiation from baffled structural panels subjected to nonhomogeneous turbulent boundary layer flow-induced excitation. A sequence of semi-analytical methods is used to estimate the nonhomogeneous turbulent boundary layer wall pressure spectrum, which is decomposed using the Cholesky technique to obtain the random wall pressure in the frequency domain. Structural panels are modeled using the finite element technique, and a coupled finite element-boundary element modeling technique is developed to estimate the sound power level radiated into the free field. Results are obtained for laminated composite structural panels with various fiber orientations.

1-(Pentafluorophenyl)propan-1-one reacts with zinc in the presence of catalytic amounts of SnCl₂ under heating in dimethyl formamide to give (2,3,5,6-tetrafluoro-4-propionylphenyl)zinc chloride and bis(2,3,5,6-tetrafluoro-4-propionylphenyl)zinc. 1,1'-(2,3,5,6-Tetrafluoro-1,4-phenylene)dipropan-1-one was synthesized from these organozinc compounds and propionyl chloride in the presence of CuI. The reaction of organozinc compounds obtained from 3-bromo-1,2,4,5-tetrafluorobenzene leads to the formation of 1-(2,3,5,6-tetrafluorophenyl)propan-1-one

The interaction of alkyl(4-X-2,3,5,6-tetrafluorophenyl)sulphanes (X = H, CF₃) containing difluoromethyl and benzyl groups as alkyl components with hydrogen peroxide in acetic or trifluoroacetic acid gave the corresponding sulphonyl derivatives. The effect of the acid used on the reaction result was established in the case of (difluoromethyl)[4-(trifluoromethyl)-2,3,5,6-tetrafluorophenyl]sulphane. The synthesis of 1-alkylsulphonyl-2,3,5,6-tetrafluorobenzenes scaling possibility to tens of grams was demonstrated. Product yields were 84-97%.

The synthesis of urea and thiourea containing adamantane and campholene fragments was performed starting from adamant-1-yl isocyanate, adamant-1-yl isothiocyanate and campholenyl amine. The synthesised compounds were modified to their oxalyl derivatives, which may be of interest for biological activity screening.

The paper presents the results of applying the methodology of chemical fingerprinting to survey the territories of industrial and natural objects, environmental accidents and objects of accumulated environmental damage in various regions of Siberia, including the Arctic zone of Russia. The data obtained by GC/MS using the capabilities of targeted and survey ecological analysis are presented. Polycyclic aromatic hydrocarbons, polychlorinated biphenyls, various classes of hydrocarbons, including relict oil biomarkers, chloro- and methylphenols, Cl-, N-, S-, O-organic compounds of various classes were considered as pollutants. The most important tools of chemical fingerprinting are considered, and it is shown that the use of a set of data on marker compounds of various types, diagnostic ratios of characteristic compounds, multi-vector chromatographic profiling of characteristic compounds ("fingerprints") makes it possible to establish the origin of pollution sources with a high degree of probability.

Drew-Dickerson Dodecamer (DDD) is one of the well-known DNA duplexes. It has been sufficiently well studied by various structure determination methods and appears to be a standard for developing new experimental techniques and molecular mechanical force fields. For this reason, the information about the dynamics of DDD on different time scales is important for constructing more accurate structural-dynamic models and carrying out molecular dynamics calculations of long-term time trajectories that allow simulation of real processes. In this work, the information on the dynamics of DDD base pairs on the milli- and microsecond time scale, currently missing from the literature, was obtained by means of imino protons’ nuclear spin relaxation ( R_1ρ) dispersion. It is shown for all the base-pairs, except for terminal and pre-terminal ones, that any dynamic processes in the range of R_1ρ method are not observed up to 300 K, but proceed on a faster time scale. For the pre-terminal GC pair, a pronounced dependence of the relaxation R_1ρ on the applied spin-lock field strength is observed, which allowed us to extract the information about the pair closing dynamics using a fast exchange model with highly skewed state populations. These data supplement the information obtained previously on the dynamics of DDD complementary base pairs by exchange-based water magnetization transfer experiments and provide a more complete view of the processes observed in DDD in relation to base pair opening-closing.