Home – Home – Jornals – Chemistry for Sustainable Development 2019 number 4

The article considers a testing approach to explanation of special and university competencies of prospective specialists through detailed analysis of professional and educational issues of the regional production cluster.

For the first time, a 15-dimensional analytical form was obtained and the potential energy of the SF₆ molecule in the ground electronic state was found ab initio . An optimal mesh of geometries was constructed, which, taking into account the full symmetry of the molecule, unambiguously determines the potential energy surface of the sixth order. Using the MP2 method with the cc-pVTZ base set, the potential energy surface of the fourth order was calculated.

The absorption spectrum of carbon dioxide confined in aerogel have been measured in the 2250-2400 cm^-1 region for the first time using a Bruker IFS 125HR FTIR spectrometer. Dependence of CO₂ half-widths on rotational quantum numbers was studied and compared with the data available in literature.

The method for estimation of spectral resolution of video spectrometers on separate sections of the sensitivity scale by comparison of experimental survey results with model (calculated for the same observation conditions) Fraunhofer’s lines from a set of preset values is suggested. It is shown that both for mass-produced spectroradiometric devices and for original video spectral devices, the maximum errors of estimation by the method suggested are within 0.5 nm at the considered test lines 700 and 587 nm.

A method is suggested for joint determination of two aerosol microphysical characteristics: the complex refractive index m = m _real + i × m _image and the spherical-particle size distribution function U(r) from the data of the nighttime vertical lidar sensing at the wavelengths 355-1064 nm. During their simultaneous estimation it is useful to minimize the discrepancy functional F(m) in the range of the physically justified m. The principal limitations due to a wider region of the global minima of F(m) appear at m ^true_image Î [0.01; 0.04] and give rise to a potential shift of the resulting values of m ^est_real and m ^est_image. A simultaneous use of several functionals gives a better estimate of m due to different sets of the respective optical characteristics. The problem in retrieving the distribution function is caused by the information content of the coarse particle measurements. The statistical regularization method offers an unambiguous estimation of U(r) for the mean radius up to 3 mm, and gives an admissible estimate for larger radii. The algorithms have been tested using 8 values of absorption, when 50 empirical models of the size distribution function are assigned to one value m ^true_image.

Based on the integrated monitoring of aerosol characteristics in suburbs of Tomsk (2000-2017), a version of classification of the surface air layer state according to “aerosol weather” types is suggested. As a basis of the measurement technique, we use the principle of separate study of the variability of the “dry matter” of aerosol particles and their condensation activity. The “aerosol weather” types was carried out in the coordinates (δ_d; Р ), where σ_d is the scattering coefficient of the dry matter of aerosol (l = 0.51 mm); P is the ratio of the mass concentration of the absorbing substance to the mass concentration of submicron particles, which reflects the degree of "blackening" of the particles. The data array is divided into two classes by the value of the scattering coefficient δ_d = 100 Mm^-1: “atmospheric haze” (s_d < 100 Mm^-1) and “haze” (s_d > 100 Mm^-1). Then the array of observational data is divided by the value P = 0.05. In each calendar season, in accordance with the parameters specified, four types of “aerosol weather” are identified, which are conventionally designated as “background” ( P < 0.05, δ_d < 100 Mm^-1), “haze-S” ( P > 0.05, δ_d < 100 Mm^-1), “smog” ( P > 0.05, δ_d > 100 Mm^-1), and “smoke haze” ( P < 0.05, δ_d > 100 Mm^-1). It is shown that the main “aerosol weather” types are reliably different in the ratio of the content of submicron and coarse particles in all seasons.

Seasonal and interannual variations in the atmospheric aerosol optical depth (AOD) are analyzed using multiyear (1995-2018) observations near Tomsk. The annual behavior of AOD is characterized by a minimum in November and maxima in early May and in July. Compared to the previous period (1995-2008), the annual behavior has been transformed so that the July maximum started to dominate. In the interannual variations we noted a significant negative trend of coarse-mode component and total AOD. The annually average AOD (0.5 mm) is 0.155 (0.126 without accounting for smokes) and the Ångström exponent is 1.32 for 2002-2018.

We presented the long-term (1994-2017) M-124 ozonometer observations of the total ozone (TO) content over Tomsk. They were used to determine the annual behavior with the corresponding standard deviations. After the long-term (a total of 8766 points) time series was processed to remove the annual oscillations, its variations were examined for a normality of the distribution. Next, the data obtained (also after being processed to remove the periodicity) was used to calculate the autocorrelation function. A harmonic, corresponding to the annual TO variations, predominates in the Fourier spectrum. Half-year oscillations with an order of magnitude lower amplitude were also detected. However, the Fourier spectrum contained no quasibiennial oscillations, quite often mentioned in the literature. They were extracted using simpler methods of statistical analysis.

The previously developed algorithm for estimating the circulation of aircraft wake vortices from measurements by a Stream Line pulsed coherent Doppler lidar has been improved by using the model of a pair of aircraft vortices in the algorithm that takes into account the ground effect on the spatial dynamics and evolution of the vortices. In a numerical experiment, it was shown that an improved algorithm allows obtaining a result with high accuracy, while the approach used earlier overestimates the lidar assessment of vortex circulation by about 10%.

A new modification of mercury vapor analyzer in atmospheric air is described. A low pressure mercury capillary lamp filled with natural isotope composition is used as a source of emission. The transverse Zeeman effect is used for the analysis. Results of the analyzer laboratory tests in various gas environments are presented. Full compensation of non-selective absorption signals is achieved. The analyzer sensitivity is estimated as ± 30 ng/m³.

The construction of the active element on metal vapor is presented. Functions of creating metal vapor and their excitation are devided between two different sources. Metal vapors are formed by induction heating of the dispenser which is located outside of the active zone. The excitation is carried out due to the commutation of the high-voltage pump pulse. The efficiency of the construction was investigated. The laser generation on copper atoms were obtained. Under conditions of independent heating of the dispenser, stable lasing was obtained on the lines 510.6 nm and 578.2 nm at a pumping pulse repetition rate of 15 kHz.

It is shown that at lower air pressure the channel of apokam discharge at low repetition frequencies (7-16 Hz) of high-voltage pulses of positive polarity and at voltage amplitudes from 26 to 35 kV is the source of the streamers. The maximum starting speed of laboratory streamers was 560 km/s. From obtained data, a hypothesis about the mechanism of the appearance of blue jets in nature was suggested. For their start, high frequencies of voltage pulses are not needed, breakdowns in the Hz range are sufficient, but the bending of the discharge channel and increased field intensity at the bending site are necessary.

Methods for phasing of an array of radiation channels for coherent combining of linearly polarized fields of narrowband fiber lasers are considered. The high efficiency of operation of the internal feedback loop based on interference of peripheral sections of radiation (Gaussian beam tails) of the phased channels is demonstrated. This method is easy to implement. It allows scaling the power of optical phased arrays and does not require massive optical elements. Equations for calculation of the optical arrangement for implementation of the feedback loop are presented along with the results of experiment on coherent combining of three beams.

Characteristics of the multiple filamentation domain in air are estimated on the basis of the numerical solution of the nonlinear Schrödinger equation in the single filamentation problem statement. The method of diffraction-beam tubes was used to describe the single filamentation of laser pulses. The effectiveness of this method for interpreting experimental results and predicting effects is shown, which is important when planning experiments. The characteristic size of small-scale intensity inhomogeneities in the laser centimeter-radius beam profile, which form a multiple filamentation domain for femtosecond pulses, is shown to be several millimeters. An increase in the original laser beam radius during telescoping increases the sizes of the initial small-scale intensity irregularities, which increases the filamentation start distance. An increase in initial beam power contributes to the elongation of the filaments and increases their number.

In order to study the wake vortices of landing aircrafts, we carried out an experiment on the airfield of Tolmachevo Airport in 2018, which involved Stream Line lidar, AMK-03 sonic anemometer, and MTP-5 temperature profiler. The limits of applicability of the radial velocity method for estimation of wake vortix parameters from lidar measurements were determinied depending on the aircraft type and the wind turbulence strength. The analysis of the experimental results makes it possible to identify features of the spatial dynamics and evolution of aircraft wake vortices during different states of the surface air layer. In particular, it is found that in the case of low average crosswind speed and moderate wind turbulence, the lifetime of the vortex formed behind a landing large MD-11F aircraft can attain almost 4 min.

An algorithm of optical vortex detection is considered and a computer application based on the algorithm is described. A vortex is localized as a branching point of an interference pattern. As the input data for the application, a BMP-file containing an image of interferogram is used; at the output, we obtain information about the vortex topological charge and coordinates. As is shown, accuracy of the algorithm developed is not lower than that of known analogues, while the amount of information obtained is larger.

The results of calculation of continuum absorption coefficients in IR H₂O spectra in 2400-10000 cm^-1 spectral region are presented. The spectral line contour used in the calculation was obtained in the frame of asymptotic line wing theory and contains parameters of both classic and quantum potentials. Parameters of the classic potential were taken from absorption calculations in 8-12 mm region. Parameters of the quantum potential were derived from fitting to Burch’s data in 2400-2800 cm^-1 region. Calculated data in the H₂O transparency windows are consistent with CRDS measurement data and with high temperature Fourier-measurement data.

Variability of the hydrobiont bioluminescence intensity in the spring and autumn periods along the coast of Crimea and its causes are analyzed based on expedition data and satellite information. It is noted that synoptic and mesoscale eddy processes have a significant impact on the vertical distribution of the intensity of the luminescence of hydrobionts, and they must be taken into account when analyzing the seasonal variability of bioluminescence parameters. The concept of integrated intensity of luminescence of hydrobionts (IILH) is suggested, which allows us to estimate the total hydrobiont biomass in the depth range, under study. It was found that the average IILH in the northern part of the Black Sea in the autumn period was more than 10 times higher than in spring. It is noted that the mesoscale eddy processes have the greatest impact on the IILH in the area of the continental slope area.

The algorithm of reconstruction of the Earth surface reflection coefficients with allowance for radiation polarization is considered. The algorithm was approbated for 5 channels of the MODIS device and three territories: south of the Tomsk region, Moscow region, and Irkutsk region. To estimate the error of the algorithm, test points in the center of coniferous large forest areas in summer season were used. Results obtained using the MOD09 algorithm with and without allowance for radiation polarization and results obtained without atmospheric correction are compared with measurement data considered to be reference ones. The comparison demonstrates that the average values obtained by the suggested algorithm with allowance for polarization are closer to the reference data than those obtained using the MOD09 NASA algorithm in the first, third, and fourth MODIS channels, and the difference on the same order of magnitude is observed in the second MODIS channel. In the eighth MODIS channel, one algorithm is preferable in some situations, and another algorithm is preferable in other situations.

The algorithm for determining cloud optical depth and cloud particle effective radii from MSU-MR daytime measurements on-board the Russian meteorological satellite Meteor-M No. 2 is presented. It is based on the physical principles of using the reflectance at 1.6 and 3.7 mm. The algorithm results are compared with the results of the algorithm developed for the AVHRR radiometer. The comparison shows that the cloud parameters retrieved with the algorithm suggested are within the acceptable limits of accuracy.

Changes in the ozone concentration during precipitation is studied on the basis of surface ozone monitoring data in Tomsk and on the Karadag. It is revealed that these changes can be both positive and negative. The maximal ozone content jumps are observed during frontal precipitations. During air mass precipitation, the sign and magnitude of the changes are defined by the daily ozone cycle. The analysis showed coincidence between an increase in the ozone concentration during precipitation with its increase in the daily cycle in 59% of cases in Tomsk and in 63% of cases on the Karadag. The coincidence of a decrease in the O3 concentration during precipitation with the ozone decrease wave in the daily cycle is observed even more often, in 85% of cases in Tomsk and in 79% of cases on the Karadag. Based on the aircraft sounding data, ozone sink from the boundary air layer is observed in some cases when the temperature stratification is changing to neutral in precipitation.

A temperature decrease occurs inside the tropospheric polar vortex during winter, which is reflected in an increase in the Arctic sea ice extent. However, the Barents Sea often turns out to be at the tropospheric vortex edge in winter, where the surface temperature is higher, which leads to a decrease in sea ice extent. Based on the ERA-Interim reanalysis data and the NSIDC satellite data, we show that the Barents Sea ice extent depends on the shape and location of the tropospheric polar vortex from December to February. Based on the example of the polar vortex dynamics in 1997/1998 and 2015/2016 and using the correlation analysis, we show that the tropospheric polar vortex edge can repeat the shape and location of the stratospheric vortex from December to March. Thus, Arctic sea ice loss as a result of a change in the tropospheric vortex edge can occur under the influence of the stratospheric polar vortex in winter.

Optical parametric oscillator based on periodically polled MgO:LiNbO₃ pumped by repetitively-pulsed Tm³⁺:Lu₂O₃ ceramic laser with a fiber-laser pumping was experimentally studied. The average power at the spectral range of 3.7-4.2 mm at the OPO output was 530 mW at the power of 7.9 W of the ceramic laser. The full efficiency of energy conversion from NIR-IR to MID-IR was 6.7% and differential efficiency was 8%. For parametric conversion of two-micron radiation from lasers (for example, on Tm³⁺:Lu₂O₃ ceramics or Ho³⁺:YAG crystals) into the mid-IR range, KTP and KTA crystals with regular domain structures are also promising.

The stress state in the neighborhood of the common edge of a freely supported composite wedge-shaped plate under transverse load has been studied. The materials of the constituent plates are cylindrical orthotropic. The problem is solved using the classical theory of anisotropic plates. Equations are derived for the hypersurface which, in the space of physical and geometric parameters, is the boundary of the region of parameters for which the neighborhood of the common edge of the composite plate is in a low-stress state (the stresses at the points of the common edge of the composite plate are limited).

A variational principle is used to study the oscillations of a reinforced thin cylindrical shell with a filler under axial compression with allowance for friction on their contact surface. The dependences of frequencies of natural oscillations on the number of waves in a circumferential direction are constructed.

Nonlinear elasticity model in current state variables is used to study the plane strain dynamics of an incompressible body, and a system of nonlinear equations of displacement and pressure is obtained. In the absence of bulk forces and in the assumption of quadratic elastic potential, the resulting equations that describe plane waves, self-similar motions, and stress fields in these motions are solved and studied. It is shown that several solutions of a certain type are possible both in wave and self-similar cases.

The dynamic buckling of an elastic cylindrical shell with a general boundary condition (composed of stiffness and damping) under an axial impact by a rigid body is considered. A dynamic equation is derived to obtain the axial stress and radial displacement of the shell. Then, by substituting the results into the energy equation, the critical condition for the dynamic buckling of the shell is obtained. The influence of the general boundary condition on the critical velocity of the impactor is analyzed. The results reveal that the boundary condition exerts no effect on the dynamic buckling of the shell before the stress wave becomes reflected from the fixed end face of the shell. After reflection, the critical velocity decreases with increasing impactor mass and stiffness, but increases with increasing damping. At times smaller than the instant when the stress wave reaches the fixed end face of the shell, the dynamic buckling occurs earlier at greater values of damping and stiffness. After stress wave reflection, the earlier dynamic buckling is observed at smaller values of damping and stiffness.

Ballistic experiments, numerical simulations, and theoretical model investigations of the penetration performance of homogeneous and jacketed rods into a semi-infinite target are presented. The striking velocities vary between 0.9 and 3.3 km/s. The effects of the jacket material, striking velocity, and initial kinetic energy on the penetration performance and damage mechanisms are analyzed. The results show that jacketed rods provide better penetration performance than homogeneous rods with the same initial kinetic energy. For a fixed ratio of the jacket radius to the core radius, it is preferable to use a jacket material with a lower density and strength that can provide the lowest required flexural stiffness.

Synthesis of a composite of powder mixtures is experimentally studied in a thermal explosion. A mathematical model for initiating a reaction that allows for the main physical and chemical phenomena changing the phase composition of a compact is formulated. It is shown that simulation results qualitatively agree with experimental data.

A simplified two-dimensional model of a lapped adhesion bond is proposed. The problem of a stress state of an adhesion bond, along the surfaces of which nonglued regions are located, is solved analytically in the assumption that the cross-sectional displacements of carrier layers equal zero. The resulting solution is a functional series, with eigenfunctions being nonorthogonal. It is shown that the presence of nonglued regions may significantly increase stresses near the edge of the adhesion layer.

The theory of large deformations is used to solve a problem of an elastic-viscoplastic material placed in a gap between two coaxial cylindrical surfaces, with one of them rotating with an alternating velocity and the other one at rest. It is shown that an increase in the stresses in a cylindrical layer due to a mechanical influence on it initially causes irreversible creep strains because of viscosity of the material and then the accumulation of plastic strains because of the arrival of stress states at the loading surface. The unloading is accompanied by a plastic strain and then a viscous one. The stress-strain parameters of the medium with a varying rotation velocity of the cylinder are calculated. Stress relaxation after its complete stop is described.

The influence of the laser beam parameters (power, motion velocity, and focus position) on the characteristics of the track being formed (size, elemental composition, and microhardness) is studied. If the difference in the laser radiation absorption coefficients in the heat conduction and “knife-like” regimes is taken into account, then the track sizes can be determined by a unified dependence on the energy parameter. The effect of the laser beam on the chemical composition and microhardness of cermet (WC-NiCrBSi) tracks is studied. Regardless of the track formation regime, these parameters are determined by the dimensionless parameter, which describes the degree of dilution of chemical substances. It is found that a track with the maximum mass fraction of tungsten and the greatest value of microhardness is formed at small values of the dimensionless parameter, which corresponds to the heat conduction regime. The microhardness of the deposited cermet structure is observed to be 4-5 times higher than the microhardness of the substrate material.

Acceleration of projectiles in ballistic devices by means of high-rate extrusion of polyethylene through a conical nozzle is experimentally and theoretically studied. Quasi-one-dimensional gas-dynamic model of a polydisperse mixture of gas and powder particles and a viscoplastic model of a deformed piston are used. The results of numerical simulation of the process under study and the results of a series of shots from a powder ballistic device are given. The influence of the geometry of a conical transition and input velocity of the deformed body on the output velocity of a projectile is experimentally investigated.

Metal shields of various thickness made of various steels and used to protect the shells of explosion chambers from damage by debris and reduce the loads on the structural elements have been studied. Dependences of the equivalent stresses in the protective shields and shells explosion chambers and the final size of the gap between the shields and the shell on wall thickness, steel grade, and initial gap size were obtained by numerical simulation. Examples of the explosion chamber designs with protective shields are given.

The article summarizes the results obtained in the studies of the distribution of thiocyanate acid complexes of iron (III), copper (II), cobalt (II), zinc and cadmium in extraction systems based on technical surfactants - potassium bis(alkylpolyoxyethylene) phosphate (oxyphos B) in the presence of sulphuric acid, alkylbenzyldimethylammonium chloride (catamin AB) in the presence of nitric acid at room temperature or their mixture at 50 ºC. It was established that the efficiency of individual surfactants as extractants is conserved both with inorganic salts and acids used as salting-out agents. It is shown that for oxyphos B extractability decreases as a sequence Fe(III) > Co(II) > Zn > Cu(II) > Cd, while for catamine AB the sequence is Cd ≈ Zn > Co(II) > Cu(II) > Fe(III), and in the case when a mixture of surfactants is used, oxyphos B is determining, which is confirmed by the extractability sequence: Fe(III) > Co(II) > Zn > Cu(II) > Cd. Oxyphos B is an analog of neutral oxygen-containing extractants, it concentrates thiocyanate acid complexes according to the hydrate-solvate mechanism, while catamin AB, anion-exchanging extractant. is more efficient in the extraction of thiocyanate complexes. The use of a mixture of the indicated surfactants allows one to carry out the process in more diluted solutions and to obtain synergetic effects in extraction.

The cobalt content of nanostructured powders obtained by means of the hydrothermal treatment of the aqueous solutions of Sn (II) and Co (II) chlorides is studied using two spectral methods - energy-dispersive (EDS) and atomic absorption (AAS). Liquid samples for atomic absorption analysis were prepared along two routes: by boiling the products of hydrothermal synthesis in concentrated acids and by fusing the products of hydrothermal synthesis with a mixture of sodium peroxide and borax, followed by diluting the liquid alloy. It is shown that low-temperature alloying of samples is most preferable to determine cobalt concentration in ferromagnetic Sn_1-xCo_xO_2-δ nanostructures. Results obtained in the present work allow us to better understand the process of the formation of Сo-doped SnO₂ nanostructures and use these structures to develop new functional materials.

The review examines the pharmacological effects of 4-(hydroxyethyl)phenol ( p-tyrosol) and its metabolite 2-hydroxytyrosol in acute ischemic disorders of the cardiovascular system and cerebral stroke. The antithrombotic, antioxidant, anti-inflammatory and antiarrhythmic activity of this compound is discussed in detail, its antimicrobial, anti-cancer and anti-metastases effects are noted. p-Tyrosol contributes to the creation of a new vascular system in the affected area (neoangiogeses), which leads not only to the restoration of blood supply in the organ affected by ischemia, but also improves geodynamics in the whole body. Studies in animals have proven the effectiveness of parenteral administration of p -tyrosol in the preoperative period of exacerbation of heart ischemia and stroke of the brain. The use of this substance leads in most cases to arresting arrhythmias and thrombosis, has a beneficial effect on the nervous system, which generally helps to reduce the area of damage to the heart and other organs with ischemia, significantly increases the number of surviving animals. The positive effect of plants containing p- tyrosol and its derivatives on the human cardiovascular system is considered, along with pharmacokinetics and the routes of the introduction of these phenolic compounds into the organism at different stages of ischemia.

The acute and chronic toxicity of several chemical reagents based on surfactants and used to treat oil-contaminated soils and sludge was evaluated. Biotesting based on the response of invertebrates and higher plants allowed us to conclude that the tested chemical reagents can be applied with effective concentrations which are safe for ecosystems. The effective concentrations were established for the phytoeffects of inhibiting the growth and development of two types of test plants (oil radish - Brassica rapa CrGC syn. Rbr, and cultivated oat - Avena sativa L.) and for the survival ability of the standardized test culture of Paramecium caudatum Ehrenberg.

The processes involved in obtaining iron-free X-ray amorphous aluminosilicate raw material of the required composition from the ash and slag waste (ASW) from the combustion of brown coal of KAFEC are investigated. Carbon thermal reduction during ASW melting is used to extract iron and its compounds. The distribution of elements - iron (Fe²⁺, Fe³⁺, Fe⁰, Fe^tot), sulphur (S) and carbon (C) - in the metal (magnetic) and silicate (nonmagnetic) fractions at different temperatures of ASW heating is shown. The equations describing the temperature dependence of the standard change of Gibbs energy for the reactions of the reduction of iron oxides are presented. The effect of silicon carbide, formed in the silicate fraction of the melt, on the recovery of iron oxides to metal iron and the resistance of foam formed due to the reducing gases are discussed. The introduction of the melt into water changes the morphology and leads to the formation of foamed heat-insulating material. Normalization of the charge during melting allows obtaining foamed materials of the required composition.

Metal matrix composite powders based on titanium carbide with titanium and high-speed steel as binders were studied by means of X-ray diffractometry, scanning and transmission electron microscopy. The composite powders were obtained by crushing the cakes formed as the products of self-propagating high-temperature synthesis (SHS) from titanium, carbon (black carbon) and HSS powder mixtures, followed by mechanical treatment in a planetary ball mill Aktivator-2S. It was stated that disintegration rate depends on metal binder content in the SHS product. To obtain the powder suitable for use in additive technologies, SHS powder of titanium carbide was ground preliminarily and then subjected to additional treatment in mixture with Ti powder in the planetary ball mill. As a result, the powder mixture consists of equiaxial granules containing fine TiC particles uniformly distributed in the Ti matrix. Results of the studies of the microstructure of samples obtained by means of selective laser melting (SLM) and electron beam melting (EBM) provide evidence of the advantages of SLM technology over EBM.