Home – Home – Jornals – Atmospheric and Oceanic Optics 2025 number 8

The helical symmetry of a permittivity tensor causes Bragg’s reflection at wavelengths close to the screw (helicoid) pitch for circular polarization of light. The study has discovered and explained the resistance of a band gap short-wave boundary to the optical axis tilt towards helical axis (normal to the plane of layers) in helical photonic structures. For a conical helical structure, the long-wavelength boundary of the reflection area changes more than for a structure with a normal cone opening with optical axis perpendicular to helical axis. Still, the wavelength for the edge mode at the short-wave boundary strictly remains under arbitrary distortions. The findings of a numerical simulation with the use of anisotropic transfer matrix and Berreman transfer matrix are coherent and confirmed by analytical derivation.

The study of the absorption of water vapor, the most powerful greenhouse gas, is important for the development of climate models of our planet. The broadening of spectral lines become of special importance for variations in temperature and pressure in the atmosphere. The paper presents the measured broadening and shift coefficients of H₂O lines by N₂O and air pressure at room temperature for 11 vibrational-rotational transitions in the 2ν₁ + ν₂ + ν₃ band, the rotational quantum number J varies from 0 to 6. The measurements were carried out on a CRDS spectrometer of high sensitivity (6.5 × 10^-11 cm^-1), the apparatus function of which is orders of magnitude narrower than the width of the lines under study. Line broadening and shift coefficients were also calculated using the semi-classical approach modification, where a correction factor is included in the calculation scheme. The obtained parameters were compared with published data. The results can be used for refining spectroscopic information in HITRAN database.

Molecular oxygen is an important gas both in the Earth's atmosphere and in the atmospheres of Mars and Venus. To determine its content the highly accurate absorption line parameter values are required. For this purpose, O₂ absorption spectra were recorded in the 7800-7990 cm^-1 range using a Bruker IFS 125HR Fourier spectrometer. The spectra were recorded at a spectral resolution of 0.01 cm^-1, a room temperature, and an optical path length of 2880 cm for five values of oxygen pressure. The intensities, broadening and shift coefficients, and parameters characterizing the dependence of broadening on the velocity of colliding molecules were determined for 55 O₂ absorption lines broadened by self pressure. A good agreement between our intensity values and high-precision measurements by other authors is shown. The self-shift coefficients are obtained for the first time.

According to the conclusion of the UN Intergovernmental Panel on Climate Change (IPCC), in order to determine the main causes of global warming caused by the increase in greenhouse gas content, an accurate assessment of their emissions and sinks is required, since there is still significant uncertainty in assessing their balance. To clarify this, the present work studies the heterogeneity in the distribution of their flows and sinks at the mesoscale level. Considering that soil plays a significant role in gas exchange processes, which significantly differ in properties on both scales, this approach seems very promising. The work uses hourly measurement data from three posts of integrated air composition monitoring: TOR station, the “Fonovaya” observatory, and the Basic Experimental Complex (BEC). It is shown that the differences in long-term (2013-2017) average concentrations between stations are within the ranges 116-195 mg/m³ for CO, 3.3-8.3 ppm for CO₂, 0.4-0.8 mg/m³ for NO, 4.6-15.5 mg/m³ for NO₂, 8.1-14.3 mg/m³ for O₃, and 2.3-6.9 mg/m³ for SO₂. Annual and daily variations in the concentration differences have been revealed for the first time. The results expand our knowledge of the dynamics of greenhouse and oxidizing gases in the atmosphere and can be useful in developing requirements for their measurement accuracy.

Turbulent processes in the atmospheric boundary layer have not been fully studied yet. The most effective tool for studying these processes is a pulsed coherent Doppler lidar (PCDL). In the work, the second version of the electro-optical unit of a PCDL LVR-2 created at the Laboratory of Wave Propagation of V.E. Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, is tested. The correctness of wind radial velocity (RV) estimates by LVR-2 during its operation in the “short” pulse mode is verified in an experiment with a Stream Line lidar. The errors in RV estimates by LRV-2 are analyzed. A possibility of using RV estimates by LRV-2 made in the vertical sounding mode to estimate the kinetic energy dissipation rate of wind turbulence by the vertical velocity spectral density method is shown. The results can be used to create techniques for testing PCDLs and determining the efficiency of such lidars in estimating atmospheric turbulence parameters.

Human activity is currently causing global warming of the planet, primarily due to the emission of greenhouse gases into the Earth's atmosphere (CO₂, CH₄, etc.). Despite international agreements and commitments made by various countries, the concentration of key greenhouse gases - CO₂ and CH₄ - in the atmosphere continues to rise. The increase in greenhouse gas levels leads to changes in the Earth’s radiation balance, which is the cause of modern climate changes affecting many extreme weather and climate events across the globe. One of the most important components of the atmospheric radiation balance is the molecular absorption of solar radiation by greenhouse gases. In this study, using the SCIATRAN model and calculations of solar radiation fluxes in the spectral range of 1-4 μm, the molecular absorption of solar radiation by key anthropogenic greenhouse gases, CO₂ and CH₄, is analyzed for their past, present, and future concentrations. The calculations were performed for three latitude zones (tropics, mid-latitudes, and subarctic) and two seasons (winter and summer). According to the calculations, the maximal molecular absorption of incoming solar radiation in the 1-4 μm range by the greenhouse gases occurs in the tropics and reaches 153-168 W/m² throughout the year. Over the period from 1750 to 2100, the molecular absorption of solar radiation by CO₂ and CH₄ is expected to increase to 0.8-1.2 W/m². The projected increase in molecular absorption of solar radiation by the end of the 21st century is close to current estimates of changes in Earth’s radiation balance, which range from 0.5 to 1.0 W/m². At the same time, the global average increase in the molecular absorption of outgoing Earth’s thermal radiation is approximately 3-4 times greater than the increase in solar radiation absorption. Both of these changes, driven by rising greenhouse gas concentrations, intensify the Earth energy imbalance and contribute to changes in the planet average temperature.

The long-term monitoring of atmospheric parameters in the surface air layer is conducted at the Fonovaya observatory. To study biophysical processes in the active soil layer, a soil temperature measurement complex was put into operation. Four-year series of soil temperatures in the 0-320 cm layer at the measuring site with natural cover are analyzed. It has been established that positive temperatures are observed from May to October to depths of 320 cm. The maximal depth of seasonal freezing did not exceed 60 cm. The standard deviation of soil temperature at all depths in winter is 2-4 times smaller than the standard deviation in summer. The daily variation in soil temperature from April to October is clearly expressed to a depth of 10 cm, below which the amplitude of the daily variation fades. From November to March, the amplitude of the daily variation is minimal (0.02 °C). The results can be used to study biophysical processes in the active soil layer and gas exchange at the soil - air boundary.

Retrieval of atmospheric aerosol optical properties from limited data volume is a crucial task for assessing radiative forcing and simulating climate in high latitudes. This work presents, for the first time, an approach to simulation of aerosol optical characteristics based on a limited set of measured input parameters using a representative ensemble of solutions. The numerical experiment involves comparison of aerosol optical properties for a typical summer background haze calculated from averaged measured parameters assumed as “reference”. In each ensemble realization, a random deviation within the range of instrumental uncertainty was introduced for each input parameter, followed by calculation of optical properties. It is shown that, for the chosen model scenario, 200 ensemble members are sufficient to achieve retrieval accuracy of 2%. The results are applicable for evaluating radiatively significant atmospheric properties based on airborne and shipborne measurements, and for validation of satellite retrievals and climate models. The proposed technique can also be used in regional aerosol pollution monitoring applications.

In the context of accelerated warming in the Arctic, the study of changes in permafrost zone characteristics is a question of high interest. The paper analyzes current and future changes in climate variables (surface air temperature, soil temperature at depth, precipitation, and snow cover depth) in the Arctic part of Western Siberia based on the ERA5 reanalysis and CMIP6 modeling data. The contribution of climate variables to the variability of the soil temperature at depth is estimated in three climate scenarios (Historical, SSP2-4.5, SSP5-8.5). The surface air temperature, soil temperature at depth, and precipitation are predicted to increase in all seasons by the end of the 21st century, while the snow cover depth will decrease. This will result in an increase in the area and depth of seasonal thawing layer and a northward shift of the southern boundary of permafrost zone. According to the SSP5-8.5 scenario, the annual average soil temperature zero isotherm will be located at a depth of ~ 6 m at latitude of 70° N (the territory between the Gulf of Ob and the Lower Yenisei Upland). Currently, the influence of the climate variables on changes in the soil temperature at depth is maximal in summer (due to air temperature) and autumn (due to snow cover) with their maximum contribution in October (up to 60% at a depth of 1 m). According to the SSP5-8.5 scenario, a decrease in the contribution of climate variables in summer and its increase in November are expected. By the end of the 21st century, the predominant contribution to the variability of the permafrost zone characteristics will belong to summer precipitation. The results can be used in studies and simulation of changes in the permafrost zone characteristics.

For efficient operation of lidar systems, highly coherent radiation with a capability of smooth wavelength tuning in a given spectral range is required. This paper presents the results of experimental studies of an alexandrite laser on the generation of coherent radiation in a compound dispersion cavity with various spectral and spatial selectors located in the external and main cavities, respectively. The mode structure of the output radiation is studied depending on the selective properties of the cavity used. The operating conditions of the compound cavity necessary for the generation of narrow-band tunable radiation in the self-injection mode are considered.

Requirements for the elements of adaptive optics systems are largely related to atmospheric conditions at their locations. The primary task is to ensure a photon flux from a sodium laser guide star (LGS) sufficient for the operation of wavefront sensors. One of ways of increasing the photon flux is the use of circularly polarized laser radiation, due to the influence of the Earth's magnetic field on the energy levels of the sodium atom. The geomagnetic field strength at Siberian observatories is 56-58 nT, which is significantly higher than that of any known observatory. Another feature is the low (about 2 × 10¹³ atoms/m²) density of sodium atoms in the mesosphere in summer. The article presents the results of numerical simulation of the return photon flux from a sodium LGS for atmospheric conditions in Siberia. Approaches to increasing the LGS brightness are considered.

The present work develops a technique for measuring the intensity of atmospheric optical turbulence in crossed optical beams. A new calibration function is suggested which allows estimating vertical profiles of the structure characteristic of the air refractive index turbulent fluctuations using covariance functions of differential jitters of solar subimage fragments detected by Shack-Hartmann sensor. Using observational data obtained at the Large Solar Vacuum Telescope (LSVT) of the Baikal Astrophysical Observatory (BAO), a characteristic vertical profile of the structure characteristic of the air refractive index turbulent fluctuations was measured. For comparison, the vertical profile of the structure characteristic of the air refractive index turbulent fluctuations was calculated based on the mean meteorological atmospheric characteristics. Both modeling and measurement data indicate the existence of turbulent layers at certain altitudes above the LSVT. The suggested approaches can be used in the optimization of adaptive optics systems, as well as in the development of optical turbulence profilers.

A new method for wireless byte-by-byte optical transmission of a digital signal multiplexed by the value of orbital angular momentum (OAM) of electromagnetic wave is presented. The transmitter is a round array of coherent laser beams formed by splitting original narrow-band laser radiation into eight channels. Data transmission channels with different OAM values are formed through interference combining of eight coherent laser beams in the far diffraction zone. The amplitude and phase of these beams vary proportionally to the values of Fourier images of information signals coming from the programmable controller to the amplitude and phase modulators of the round array of laser beams. The wave field propagates in space and comes at the input of the receiving telescope. To demultiplex the signal, the sorter of OAM modes is used. It comprises beam splitters, vortex phase plates, focusing lenses, photodetectors, and a comparator. The sorter distributes the incoming radiation into eight channels, which differ in the OAM values in the range from -3 to +4. Upon the processing, the structure of a digital signal byte is reconstructed at the vortex phase plates at the photodetectors inputs. The combining of eight laser beams in the comparator yields the complete structure of the transmitted digital signal. A conceptual diagram of an experimental setup implementing this method is proposed. The possibility of its practical implementation is demonstrated through numerical simulation. Some technical methods improving the efficiency of the method are suggested, and the advantages of the method are described.

Dependence on time and conditions of propagation of a laser beam integral (radius and displacement of the energy center) and local (intensity at a point) parameters was determined numerically. The obtained functions were expanded into a trigonometric Fourier series, and the precision of expansion was assessed. The mathematical models are presented as software applications, using which the dependence of the frequency of spectral components on the wind speed and the inner turbulence scale were derived. The results of the study can be used in the design of adaptive optics systems, in particular, for formulation of requirements for frequency of correction for atmospheric distortions, which is one of the main characteristics of laser beam control unit.

Results of a laboratory experiment with a laser beam propagated in an artificially created turbulence are analyzed. Methods are described which transform a sequence of video frames with recorded intensity distribution into characteristics of laser radiation. As a result of the expansion of time-dependent functions into a trigonometric Fourier series, the frequency of parameter variations was determined and requirements for the operating speed of an adaptive system designed to compensate for distortions were formulated.

To detect ecotoxicants in the atmosphere by absorption spectroscopy, it is necessary to know their spectroscopic parameters. The absorption spectra of chloroform in a gas phase in the 2-mm wavelength subranges, where spectroscopic data are absent, were measured using high resolution spectrometer with phase-switching. The experimental results were compared with theoretical estimates of the absorption rotational line central frequencies. After preliminary measurements in the 118.6-118.9 GHz subrange, their comparison with the literature data, and confirmation of the possibility of reliable detection of absorption lines in the spectrum, the absorption lines for CH³⁵Cl₃ in the ground and in excited vibrational states (ν₃, 2ν₃) in the 131 ÷ 132, 137 ÷ 139, 150 ÷ 152, and 156 ÷ 158 GHz spectral ranges have been revealed and identified. Presented results can be used for detection of CH³⁵Cl₃ in the atmosphere.

The article analyzes the quality of collections of experimental vibrational-rotational energy levels and transitions of the main isotopologue of the water molecule placed in the information system (IS) W@DIS. Software for automatic support of the quality of the collection of energy levels and transitions when loading new data sources was created. This software performs sequential double filtering using the latest version of empirical energy levels, as well as quasi-empirical energy levels. A brief description of the introduced quasi-empirical energy levels and their role in updating the quality of data is given. Statistical data on each of the collections are presented, subsets of collections suitable for decomposition of expert wave numbers and lower-level energies are distinguished.

This study is devoted to the development of a trace method for monitoring tritium isotopologues of water (HTO and T₂O) using infrared (IR) spectroscopy. The actuality of the work is due to the need to monitor tritium, a radioactive isotope of hydrogen formed as a result of man-made processes, including accidents at nuclear power plants. The main objective was to estimate the sensitivity of IR spectroscopy for detecting low concentrations of HTO and T₂O in water vapors, which is critical for the operational monitoring of radioactive contamination. The work uses spectroscopic data from theoretical calculations and experimental measurements, including absorption line parameters from the spectra.iao.ru and HITRAN2020 databases. The line-by-line method is used to simulate transmission taking into account the refined line broadening coefficients calculated using the author's technique. The main results include: improved line broadening parameters, which increased the simulation accuracy; revealing of optimal spectral ranges for detecting HTO (1227-1236, 2219-2226 cm^-1), and the intervals for T₂O (930-990, 1092-1010 cm^-1) located in the atmospheric window (8-12 μm); estimation of the detection threshold for tritium isotopologues at a level of 0.01-0.05% of the concentration of the main isotopologue H₂¹⁶O. The obtained results open up opportunities for creating real-time tritium monitoring systems, which is important in assessing environmental and radiation risks. Promising areas for further research are adaptation of the method to field conditions taking into account the atmospheric influence and integration of spectroscopic data into climate models. The work contributes to the development of environmental monitoring and radiation safety methods.

A method for modifying nopinane-annelated 4,5-diazafluorene by introducing butyl groups and an additional amide group is proposed. Stereoselectivity of the formation of a single isomer by the substitution of a benzyl methylene group of pinane system is demonstrated. The structure of the new substances is established using a set of physicochemical methods. The synthesised substances can be promising tridentate ligands and extractants for d- and f-elements.

Triarylmethyl radicals (TAM, trityls) presented in the form of water-soluble tricarboxylic acids are widely used in biomedical, chemical and spectroscopic studies. In most applications, trityl radicals demonstrate high stability against various redox agents. An exception is the oxidative degradation of TAM to diamagnetic quinone methides. A typical active form of oxygen in biological environments, superoxide (O₂^·- or HO₂^·) is involved in this reaction. The details of this process have been studied in order to identify the factors controlling the channel of TAM consumption. The study has been performed using quantum chemical calculations (by means of the density functional theory) on a model trityl - triphenylmethyl radical presented in the form of a monocarboxylic acid. Alternative routes differing in the nature of protonation of key reagents in the aqueous medium have been considered. It has been established that protonation/deprotonation of reagents controls the barrier of the rate-limiting stage and, thus, the rate of the observed decarboxylation. This conclusion is in good agreement with the experimental data on the dependence of the reaction rate on pH. Among the reaction pathways considered, the most favourable one is the interaction of TAM anion, containing deprotonated carboxyl group, with protonated superoxide (neutral hydroperoxide radical HO₂^·). Taking into account the identified features, an analysis of alternative oxidation routes of another TAM derivative was carried out, for which the role of the key stage is assigned to proton elimination.

The reaction of 2-R-5,5-diethyl-2-ethynylpyrrolidin-1-oxyls (where R = Et, i-Pr) with esters of azidoacetic and p-azidobenzoic acids in the presence of copper(I) salts has been studied. It was found that the presence of the bulky isopropyl substituent prevents the reaction with ethyl ether of p-azidobenzoic acid and decreases the yield of the corresponding triazole in the reaction with methyl ester of azidoacetic acid. The resulting nitroxides demonstrated a high degree of resistance to reduction by ascorbic acid, which was comparable to the stability of 3,4-bis-hydroxymethyl-2,2,5,5-tetraethylpyrrolidin-1-oxyl.

Results obtained in the studies of living systems using chemical fingerprinting methodology are presented. Gas chromatography - mass spectrometry and the tools of chemical fingerprinting were applied to obtain the chromatographic profiles and to determine the isomeric-homologous series of characteristic target metabolites of various classes of the objects of plant origin and cuticular lipids of insects at different stages of ontogenesis and living in different climatic conditions. The main target metabolites considered herein are hydrocarbons, ketones, alcohols, fatty acids and their hydroxy-derivatives, esters, alkylresorcinols, di- and triterpenoids, phenol acids, and lignans. The approach used in the work makes it possible to establish the composition of characteristic target metabolites in various living systems and their changes in the processes occurring under the influence of abiotic and biotic factors, targeted gene mutations, which can be used both in fundamental and applied research, including the improvement of approaches to biological control of economically important insect pests in agriculture.

Neuromodulatory properties of two aza analogues of amantadine - 6-amino-5,7-dimethyl-1,3 -diazaadamantane 3 and 7-amino-1,3,5-triazaadamantane 4, as well as a synthetic precursor of compound 3 - 5,7-dimethyl-1,3-diazaadamantan-6-one 2, - were investigated in experiments on outbred male mice. Azaadamantanes and the reference drug amantadine hydrochloride 1 were administered intraperitoneally in an aqueous solution at a dose of 20 mg/kg. Control animals were administered water. In a model of neuroleptic haloperidol-induced parkinsonism, it has been shown that 2 and 4 are more potent agents in dopamine-stimulating activity than amantadine. In the model of arecoline tremor, azaadamontanes 3 and 4 were found to have higher M-cholinergic blocking activity than amantadine. All azaadamantanes have been shown to potentiate adrenergic neurotransmission but do not have GABAergic activity. The most promising agent is triazaadamantane 4, which has demonstrated pronounced dopamine-stimulating and M-cholinergic blocking properties with moderate adrenergic activity.

Conjugates of drugs and biologically active compounds with stable nitroxides are often used to study pharmacokinetics, the biochemical mechanisms of activity and distribution of the active substance in body tissues using electron paramagnetic resonance and magnetic resonance imaging. In this work, we synthesised a paramagnetic analogue of ibuprofen, a known cyclooxygenase inhibitor, retaining the free carboxyl group for critical interaction with the active site of this enzyme. For this purpose, ibuprofen was subjected to nitration into the aromatic ring, the nitro group was reduced, and the resulting amine was acylated with 2,2,5,5-tetramethyl-3-pyrroline-1-oxyl-4-carboxylic acid chloride.

A novel predictive model based on meta-learning algorithms for estimating the energy gap between the frontier molecular orbitals of aromatic p-conjugated molecules is presented. The main goal of the study was to develop a highly accurate and robust model capable of replacing computationally expensive quantum chemistry calculations, in particular the methods based on density functional theory, for screening organic compounds in optoelectronic applications. The filtered subset of the publicly available PubChemQC PM6 database was used as the primary dataset. Molecular structure was encoded using Morgan fingerprints, which served as input for training three base models: Random Forest, Gradient Boosted Trees, and a fully connected Neural Network. Among these, the Gradient Boosted Trees model achieved the best performance (the mean absolute error was 0.1795 eV). To improve prediction accuracy, a meta-model was implemented and trained on the outputs of the above-mentioned base models. This approach demonstrated improved accuracy: the final mean absolute error was 0.1744 eV, which is 8 % better than simple averaging and 3 % better than the best-performing individual model. The proposed approach can be further enhanced by expanding the dataset and incorporating additional models, which pave the way for more accurate and efficient prediction of the properties of organic conjugated molecules in optoelectronics.

2,7-Di(thiophen-2-yl)-9H-(4,5-diazafluoren)-9-one (TDAFO) was synthesised and its crystal structure, optical and electrochemical properties were studied. The target compound was obtained using the Stille reaction from 2-(tri(n-butylstannyl)thiophene and 2,7-dibromo-4,5-diazafluoren-9-one. Using X-ray diffraction analysis, the crystal structure of TDAFO was solved, and the formation of weak π-stacking interactions, C-H…N and C-H…O hydrogen bonds was revealed. The oxidation and reduction potentials of TDAFO were evaluated by cyclic voltammetry, and the possibility of TDAFO electropolymerisation on conductive coatings was demonstrated. The optical properties of both the monomer and the polymer obtained by electrochemical polymerisation were studied. The photoluminescence quantum yield of TDAFO was determined to be 7 % in solution and 13 % in the crystalline form.

Рiperidine nitroxides have found many applications in various fields of science and technology. The introduction of bulky alkyl substituents in an adjacent position to the N-O fragment imparts useful characteristics to such radicals, increasing their stability in biological samples, enhancing their protective antioxidant properties and making them valuable regulators of radical polymerisation. A sterically hindered nitroxide with a spiro-2-hydroxymethylcyclopentane moiety and two ethyl groups at positions 2 and 6 of the piperidine ring, respectively, was synthesised. For this purpose, the condensation of 2-(2-aminoethyl)-2-methyl-1,3-dioxolane with diethyl ketone under the conditions of acid catalysis was carried out. The resulting spirocyclic piperidine was oxidised to aldonitrone. Spiro-2-hydroxymethylcyclopentane moiety was assembled via the reaction with 4-pentenylmagnesium bromide, followed by oxidation and intramolecular 1,3-dipolar cycloaddition and reductive opening of the isoxazolidine ring. The resulting dispirocyclic piperidine was oxidised to the corresponding nitroxide, 8-[(hydroxy)methyl]-13,13-diethyl-1,4-dioxa-12-azadispiro[4.1.4.3]tetradecane-12-oxyl. The kinetics of reduction of the latter by ascorbic acid has been studied.

Structural modification of the Finland-type trityl core by replacing carboxyl groups by alkoxymethyl substituents (CH₂OCH₂CO₂H) resulted in new triarylmethyl radicals, which showed extremely high stability in the presence of superoxide.

The work is concerned with the synthesis of biologically active substances based on monoterpenoids through their chemical modification to increase the pharmacological potential of the synthesised compounds. The starting substances to synthesise urea derivatives were adamant-1-ylisocyanate and monoterpenoid amines with a perillyl or myrtenol fragment. These monoterpenoid substituents were chosen on the basis of literature data suggesting that the indicated compounds exhibit activity with respect to the nervous system in various animal models. On the basis of these ureas, imidazoline-2,4,5-triones were synthesised. These urea derivatives potentially possess lower lipophilic properties.

The structure of asphaltenes of oils sampled in various oil and gas provinces and differing from each other in chemical types and contents of asphaltene components has been studied using an oxidation reaction catalysed by ruthenium ions. Structural fragments, covalently bound through C_ar-C links with the aromatic rings of their molecules, and the compounds occluded in the hollow cells of macromolecular structures in asphaltenes are shown to be present in all the samples under investigation. The covalently bound fragments are represented by normal and branched alkanes, cheilanthanes, gopanes, and aromatic structures of the biphenyl type. Typical biological markers, n-alkanes and hopanes, have been identified among occluded compounds. n-Alkylbenzenes, n-alkyltoluenes, n-alkylxylenes, n-alkyltrimethylbenzenes, and alkylbenzothiophenes are additionally found in the composition of non-oxidised naphthenic aromatic oil compounds.

Two- and three-component systems of deep eutectic solvents (DES) based on polyatomic alcohol - pentaerythritol (PER), carbonic acid diamide - urea (carbamide, CA) and quaternary ammonium salt - choline chloride (CC) were synthesised: PER-CC, PER-CA, CC-CA, PER-CA-CC. Eutectic points in the obtained DES systems were determined. It is shown that the lowest melting point (-14.5 °C) is observed for the three-component DES system based on PER-CA-CC with the molar component ratio of 1.3 : 2.4 : 1, respectively. The solubility of this three-component system was determined by dissolution in water prior to precipitation. The density of the aqueous solutions of binary DES systems was determined to be within the range of 1.2158-1.2458 g/cm³. The presence of hydrogen bonds in binary and ternary DES systems was revealed by IR spectroscopy: CC acts as an acceptor of hydrogen bonds, while PER and CA act as donors. The presence of hydrogen bonds between DES components provides the formation of stable molecular complexes and lowering of the melting/crystallisation points of DES compositions due to intermolecular bond weakening and destruction of the crystal structures of initial substances.

Extrusion-based 3D printing methods are widely used to fabricate tissue-engineered constructs for regenerative medicine with specific dimensions, shapes, and properties tailored to the nature of the wound defect. High-viscosity solutions of the anionic polysaccharide sodium alginate show a potential as a base material for developing hydrogel inks for 3D printing. However, printing with sodium alginate solutions presents technical challenges due to the need for rapid gelation immediately after extrusion to form an elastic gel. This study demonstrates the possibility of controlling the viscosity of sodium alginate solutions by introducing a gelation modifier - ferulic acid, which participates in the formation of an entanglement network. Using IR spectroscopy, the nature of interactions in alginate-based materials obtained in the presence of ferulic acid was investigated. The conditions for producing highly hydrated gel structures based on an ionogenic polysaccharide solution and ferulic acid were optimised using piston-based 3D printing.

This article is concerned with the urgent problem of atmospheric air pollution in the post-industrial phase of the development of mining regions. Methodological approaches to the hygienic diagnostics of local aerosol pollution of the atmosphere have been elaborated. The modeling object was the Ursk dump of barite-pyrite loose material, formed in the 1930s after gold extraction by cyanidation in Ursk settlement, the Kemerovo Region. The field model of the dump was formed by the samples of sulphide-containing wastes collected from the object in summer. At the first stage, a theoretical analysis of the information presented in the literature on the physicochemical and toxic properties of aerosol particles in the submicron range, which pose risks to the environment and public health in mining areas, was carried out. At the stage of hazard identification, the application of the field modeling of atmospheric migration processes of target particles and mercury vapour from a sulphide-containing waste disposal facility was scientifically justified. At the modelling stage, which consisted of heating the waste samples to a temperature of 27.1±0.04, 33±0.1 and 50±0.3 °C, the trends of air concentrations of aerosol particles of various ranges and their correlations were estimated. At the design stage, the probability of accumulation of submicron particles and mercury vapour in the air basin, which poses a significant danger to the environment and public health, was determined. The data obtained from the results of simulation are intended for information provision of planning and implementation of measures for land reclamation and environmental improvement.

The effect of indium oxide additive on the properties of Pd-containing catalytic systems Pd/WO₃-ZrO₂ based on zirconia modified with tungstate anions (tungstated zirconia catalysts) and Pd/WO3-ZrO₂/Al₂O₃ catalysts in which the active component WO₃-ZrO₂ providing the acid properties of catalysts is introduced into the porous matrix of the alumina support is investigated. It is shown that the introduction of indium oxide additive in an amount of 0.5-1.5 wt% into the catalyst composition enhances their activity and also increases the yield of the target reaction products - octane isomers. The introduction of 0.5 wt% indium oxide into the composition of tungstated zirconia catalysts supported on alumina leads to an increase in octane conversion by 5.8 % and a rise in the yield of the target reaction products - octane isomers by 4.7 wt%. For Pd/WO₃-ZrO₂ catalysts, the introduction of indium oxide additive in an amount of 1.0-1.5 wt% leads to an increase in octane conversion by 28.0-38.7 %, with a rise in the yield of isomers by 17.0-21.3 wt%. The positive modifying effect of indium oxide additive to the Pd/WO₃-ZrO₂ catalysts is due to an increase in the proportion of the active tetragonal phase of zirconia from 33 to 43-63 %, a rise in the specific surface area from 28 to 38-40 m²/g and an increase in total acidity according to temperature-programmed desorption of ammonia from 113 to 122 μmol/g. The introduction of the active component into the porous alumina support causes an increase in the proportion of weak acid sites of the catalysts, which provides an increase in selectivity to octane isomers. The addition of indium oxide allows regulating the phase composition, textural characteristics and acid properties of palladium-containing tungstated zirconium catalysts, which determines their catalystic activity, and allows obtaining active and selective catalysts of octane isomerization - Pd/In₂O₃-WO₃-ZrO₂ and Pd/In₂O₃-WO₃-ZrO₂/Al₂O₃.

The article examines the etymology and history of the evolution of the scientific terms “yedoma” and “ice complex”, widely used by scientists of different fields in the study of landscapes, geomorphological conditions, Quaternary geology and the history of cryolithogenesis in the North-East of Eurasia. Some problems in the use of these terms, inaccuracies and discrepancies recorded in reference and educational literature are considered. Based on new data on the structure of ice-rich deposits obtained over the past quarter of a century, new grounds for their clarification are given and their definitions are proposed. It is shown that terminological problems are often associated with under-exploration of the objects being defined, but to no lesser extent they are determined by the verbal carelessness of researchers in the presentation of their results.

This article presents the results of the permafrost research of the Oka Plateau in the Eastern Sayan Ridge. The complex of scientific research works carried out in the Sentsa River valley involved parametric drilling, geothermal regime observations in boreholes, cryolithological analysis of unconsolidated sediments, and petrographic studies of ground ice, as well as its structural and genetic features. It was established that the geological section down to 45 m consists of clays, clayey silts, silts and sands with ice interlayers and lenses. Permafrost thickness in the Sentsa River valley does not exceed 44 m, and a mean annual ground temperature at a depth of 10 m ranges from -1.1 to -2.1 °C. The parameters of the structure of ground ice indicate its segregation and injection origin. The stable multi-year positive trend in the mean annual air temperature on the Oka Plateau contributes to a gradual increase of the frozen sediments temperature in the layer of annual heat fluctuation, the destruction of ice-mineral frost mounds and the lowering of the surface.

The article presents the results of a study of the patterns and causes of heterogeneity in the cessation of runoff in October and the first half of November in the upper reaches of the mountain rivers of the Upper Kolyma. Three levels of heterogeneity were identified. The first level is associated with the diversity of geological terranes in the study area. The highest runoff values (annual layer, runoff modules in September and in the first winter month of October) are found in the area of the Viliginsky terrane which lithodynamic complex is dominated by tuffaceous rocks. The lowest values are observed in the Inyali-Debinsky terrain, where clayey and siliceous shales prevail. The second level of heterogeneity is expressed in the duration of runoff after the onset of the winter low water period, which varies from several days to 45 days. This is determined by the recharge of groundwater due to the melting of ice at the base of the seasonally thawed layer (STL). Consequently, the heterogeneity of this level is an indicator of water saturation of seasonally aquiferous sediments near the riverbed and of the ice content of the base of the seasonal aquifer. The third level of heterogeneity reflects the presence or absence of a water-absorbing talik above the hydrometric alignment.

The analysis of satellite imagery and field data allowed a reconstruction of gradual glacier shrinkage in the Tavan-Bogd transboundary massif (Altai) from the maximum of the Little Ice Age to 2024. Information on the glaciers has been obtained for the maximum of the Little Ice Age and the years 1968, 1977, 1989, 2000, 2010, 2020, and 2024. Since the Little Ice Age maximum, the area of the Tavan-Bogd glaciers decreased by 49 % whereas the firn line increased in altitude by 149 m, on average. An estimated volume of the glaciers decreased by 69.1-75.7 %. A vertical range of glaciation reduced by 330 m. Glacier shrinkage is accelerating which has manifested itself for the fronts of large valley glaciers after 2010, and for the total glaciation area since 2020, when area losses began to average 1.6 % per year. Contrasts in the aspect distribution of glaciers have increased, which may reflect an increase in the incoming solar radiation. Valley glaciers remain dominant in area, but their share in the total area has decreased. Accelerated glacier shrinkage appears to be a delayed response to an abrupt rise in summer temperatures during the 1990s.

Aufeis are widespread in the permafrost zone. Morphometric characteristics are indicators of the aufeis dynamics and can be used in theoretical research and for practical purposes. Their assessment is associated with technical difficulties, significant time and labor costs when using contact field methods. In this paper, we propose a technique for determining the area and volume of aufeis by aerial photography using post-processing of data from global navigation satellite systems. It makes it possible to achieve centimeter accuracy in determining altitude and plan coordinates. The areas and volumes of the object on the dates of surveys were calculated based on the data of field work at the Anmangyndinskaya aufeis during 2021-2023. A total of 21 aerial photographs were processed during both the formation and melting periods of aufeis using unmanned aerial systems and materials from high-precision ground geodetic profiles. The maximum ice volume varied from 6.71 million m³ on 30.03.2023 to 5.17 million m³ on 24.03.2022, and amounted to 5.41 million m³ on 24.05.2021. The calculated weighted average of ice thickness varies from 0.50 to 1.69 m. The mean error in determining the average aufeis thickness by aerial photography compared to ground-based geodetic measurements is 11 % after identifying and adjusting for the systematic error. A comparative analysis of the aufeis area was performed using Sentinel-2 satellite images and aerial photography. The error in determining the area using space images during the snow-free period is 11 %, and during the period of snow cover - 38 %.

Mark Mikhailovich Shatz, Candidate of Geographical Sciences, passed away on September 23, 2024, at the age of 81, after a long serious illness. He worked at the Melnikov Permafrost Institute in Yakutsk for several decades where he became a renowned specialist in the fields of regional geocryology, remote sensing of permafrost regions, and northern geoenvironmental studies. Dr. Shatz will be remembered as a remarkable permafrost researcher.