bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in the Surface Wind Associated with Atmospheric Cyclones at Extra-Tropical Latitudes of the Northern Hemisphere in Recent Decades
Authors: Akperov M. G. , Mokhov I. I.
Published: April 2024

We obtained quantitative estimates of seasonal and regional features and changes in cyclone activity in the atmosphere of the Northern Hemisphere and determined the contribution of extratropical cyclones to the formation of corresponding features and changes in the surface wind, using ERA5 reanalysis data for recent decades (1979–2021). According to these estimates, the contribution of extratropical cyclones to surface wind speeds in the regions of their high occurrence reaches 60% in winter and 50% in summer. The strongest contribution is related to intense cyclones: about 60% in winter and about 25% in summer.
Integration of Satellite Monitoring and Mathematical Modeling in the Analysis of the Nature of Elevated Sulfur Dioxide Concentrations in the Surface Air of the Northern Part of Finland
Authors: Dryukova E. D. , Nerobelov G. M. , Sedeeva M. S. , Kiselev A. V. , Mahura A. G. , Gorny V. I.
Published: April 2024

The article is devoted to the investigation of the nature of the increment in surface concentration of toxic gas sulfur dioxide (SO2) in Northern Finland. The study is carried out for June 2011 when the increased near-surface SO2 concentration was registered at Finnish observation station Inari Raja-Jooseppi together with the surface wind blowing from the territory of the Kola Peninsula. The hypothesis of natural increment of near-surface SO2 concentration as a result of Grímsvötn volcano eruption (Iceland) is verified using satellite SO2 observations by OMI, numerical weather prediction and atmospheric chemistry model Enviro-HIRLAM and particle dispersion model HYSPLIT. The results show that not only local man-made sources, but also the remote transfer of pollutants from volcanic eruptions can cause an increased near-surface SO2 concentration. To verify this hypothesis, a large set of statistics is required in Northern Finland during periods of volcanic activity in Iceland.
Rossby Waves and Zonal Flux Anomalies in Hadley and Ferrell Cell Analogs of the General Atmospheric Circulation: Model and Experiments
Authors: Gledzer A. E. , Gledzer E. B. , Khapaev A. A. , Chkhetiani O. G.
Published: April 2024

The circulation of the form of axysimmetrically flow with induced anomalies (disturbances) in closed rotating annular channel with conical bottom is generated by sources-sinks and MHD-method. The reducing of external forcing affects the changes of the anticyclones translation speed, but not the cyclones. The great part of moving anticyclones can disappear or stoped or new quasistationary cyclones may realized, whereas there are no change in the flow pattern in the sector where external anomalies take a place. But the variations in averaged parameters of the flow vortex are distinguished for the entire channel area and for their part. These anomalies physically are the weakness of subtropical Hadley cell with diminishing of passats in some sector of subequatorial atmospheric circulation and also the weakness the westerlies in the middle latitudes. The superposition of blocked and transported vortices are investigated with the help of simple analytical resonance interaction model for transient (with the maximum of velocity) modes in the shear flow. The amplitude of stationary background and the famous Sverdrup relation of the free surface streamfunction in the west oceanic shore intensification are affected in the same way from the beta-effect.
Comparison of Satellite and Ground-Based Measurements of Tropospheric Ozone Columns in the Vicinity of St. Petersburg
Authors: Virolainen Ya. A. , Nerobelov G. M. , Polyakov A. V.
Published: April 2024

The monitoring of tropospheric ozone in world science has recently received considerable attention since ozone in the troposphere is both a greenhouse and a pollutant gas. It also plays an important role in various chemical and photochemical processes. Ground-based measurements can be used to assess the quality and to validate satellite measurements of the global ozone distribution. The time series of ozone tropospheric columns in the 0-8 km layer derived from spectral measurements of the IASI satellite instrument using two different algorithms (IASI_LATMOS and IASI_LISA), as well as from joint measurements by the IASI and GOME-2 instruments (IASI-GOME2) were compared to ground-based measurements using the Bruker IFS 125HR Fourier spectrometer at the NDACC St. Petersburg site for 2009–2021. IASI_LISA and IASI-GOME2 on average overestimate ground-based ozone measurements by 9.8 and 5.1%, respectively, while there is no bias between the IASI_LATMOS and FTIR data. The standard deviations of the differences between ground measurements and the IASI_LISA and IASI_LATMOS data do not exceed 12–13%; for the IASI-GOME2 data they are 24.5%. Ground-based and satellite measurements agree better in spring and summer. Ground-based and IASI_LATMOS demonstrate a statistically significant negative trend in the ozone columns in the 0–8 km layer in the vicinity of St. Petersburg for the period 2012–2021, amounting to –0.71 ± 0.35% per year and –0.60 ± 0.21% per year, respectively.
The Ratio of the Second and Third Turbulent Moments in the Urban Boundary Layer of the Atmosphere on the Example of Data from the Moscow State University Eddy Covariance Tower
Authors: Drozd I. D. , Artamonov A. Yu. , Barskov K. V. , Gavrikov A. V. , Pashkin A. D. , Repina I. A. , Stepanenko V. M.
Published: April 2024

This work is devoted to testing the hypothesis about the presence of a diagnostic connection between the second and third moments of the hydrodynamic quantities \({{c}_{1}}\) and \({{c}_{2}}\) in the atmospheric boundary layer above a geometrically complex surface: \(\overline {w{\kern 1pt} 'c_{1}^{'}c_{2}^{'}} = C{{S}_{{{{c}_{1}}}}}{{\sigma }_{{{{c}_{1}}}}}\overline {w{\kern 1pt} 'c_{2}^{'}} .\) To test this ratio, a seven-month series of high-frequency measurements on an eddy covariance tower installed at the Meteorological Observatory of Lomonosov Moscow State University was used. Based on the statistical distribution of the third moments, the optimal methods for analyzing the reliability of the dependence under study were determined. For the first time on a large series of data, a statistically valid assessment of the validity of the tested hypothesis was obtained in the conditions of the urban underlying surface. The influence of stratification conditions and the nature of the underlying surface in the area of flux formation on the fulfillment of ratio second and third moments is studied. It is established that for the third moments \(\overline {w{\kern 1pt} 'w{\kern 1pt} 'T{\kern 1pt} '} ,\) \(\overline {w{\kern 1pt} 'T{\kern 1pt} 'T{\kern 1pt} '} ,\) \(\overline {w{\kern 1pt} 'u{\kern 1pt} 'u{\kern 1pt} '} ,\) and \(\overline {w{\kern 1pt} 'v{\kern 1pt} 'v{\kern 1pt} '} \) relation second and third moments is valid in 80% of cases.
Electricity of the Undisturbed Atmospheric Boundary Layer of Middle Latitudes
Authors: Anisimov S. V. , Aphinogenov K. V. , Galichenko S. V. , Prokhorchuk A. A. , Klimanova E. V. , Kozmina A. S. , Guriev A. V.
Published: April 2024

The atmospheric boundary layer is the lowermost part of the atmosphere, the turbulent dynamics and electrodynamics of which are determined by the complex organization of processes in a dissipative environment with energy input from many sources. Regions of the atmosphere undisturbed by thunderstorms and precipitation are characterized by low-energy electrical processes, for the study of which requires a developed instrument base and knowledge of the methods of synchronous spaced high-precision measurements of several physical quantities. The paper presents the results of recent studies of electricity of the atmospheric boundary layer of mid-latitudes carried out using the measuring complex of Borok Geophysical Observatory IPE RAS and numerical modeling. Quantitative estimates of the average values and variability of small ion concentration, the corresponding components of electrical conductivity, and atmospheric electric field intensity are performed. Two types of electric structures formed by the electric current flow through a turbulent medium with inhomogeneous conductivity are defined.
Analysis of the Features of Water Circulation in the Northern Part of the Black Sea for Different Seasons on the Basis of the Results of Numerical Modeling with the Assimilation of the Data of Hydrological Surveys in 2016
Authors: Demyshev S. G. , Evstigneeva N. A.
Published: April 2024

The analysis of the dynamic and energy characteristics of water circulation in the northern part of the Black Sea was performed on the basis of the assimilation in the numerical model of the data of three hydrological surveys in 2016, carried out on expeditions of 87, 89 and 91 cruises of the R/V Professor Vodyanitsky (summer, autumn and autumn-winter seasons). Numerical experiments were implemented on a horizontal grid (~1.6 km × ~1.6 km) with 27 vertical horizons and an atmospheric effect close to the real one was used. A procedure of assimilation of the observational data was based on the Kalman filter, taking into account the heterogeneity and nonisotropy of the errors of the estimates of the temperature and salinity fields. The integral energy terms in the kinetic and potential energy budget equations for three seasons were estimated. In the summer season, there was a slight weakening of the RC and the main mechanism for the formation of anticyclonic eddies near Sevastopol and near the southeastern shores of Crimea was baroclinic instability of the current (as evidenced by the increase in the slope of isopycnical surfaces and negative values of the work of the buoyancy force). An anticyclonic eddy near Yalta with a radius of about 25 km was generated due to the development of shear instability of the current. In the autumn season, the RC jet was pressed to the shore and there was a decrease in the number of eddies in comparison to the summer season. The formation of anticyclonic eddies with a radius of about 35–40 km in the western part of the region was caused by barotropic instability of the current, the formation of eddies along the Crimean coast – by baroclinic instability. In the autumn-winter season, the RC had a pronounced jet character and there was an increase in the processes of baroclinic instability with the generation of eddies of different scales between the coast and the RC, as well as in the area, located between 31.5 and 33° E, with the weakening of the wind effect. During all seasons, small-scale anticyclonic and cyclonic eddies could be generated along the western and eastern coast of Crimea in the upper layer when current flowed around the coastline and inhomogeneities of the bottom topography under the action of weak winds.
Regular and Chaotic Oscillations in a Geostrophic Flow with Vertical Shear
Authors: Kalashnik M. V. , Chkhetiani O. G.
Published: April 2024

In the framework of a two-level quasi-geostrophic model, the stability of flow with a constant vertical shear is investigated. Analytical expressions for the increment of perturbation growth in linear stability theory were obtained. The Galerkin method with three basic Fourier harmonics was used to describe the nonlinear dynamics of perturbations. A nonlinear system of ordinary differential equations is formulated for amplitudes of Fourier harmonics. It is shown that in the absence of bottom friction all solutions of the system describe periodic mode of nonlinear oscillations or vascillations. The situation changes fundamentally in the model with bottom friction. In this case, for a wide range of parameter values, the system solutions exhibit complex chaotic behavior. Thus, chaos or turbulence emerges for large-scale motions.
Stratospheric Ozone Variations Over Obninsk from Data of Lidar and Satellite Measurements
Authors: Korshunov V. A.
Published: April 2024

Analysis of variations of stratospheric ozone content at 13–18, 18–23 and 23–30 km layers is presented from data of lidar and satellite measurements in 2014–2022 over Obninsk city (55.1° N, 36.6° E). Modeling of deviations from seasonal run for separate quarters of year are fulfilled by using of linear regression method. Impact factors under consideration are quasi-biennial oscillation of zonal wind in tropical stratosphere (QBO), Arctic oscillation (AO), El-Nino – Southern oscillation (ENSO), solar activity (SA), volcanic aerosol (VA) and polar stratospheric clouds (PSC). Enhancement of ozone content is observed in eastern QBO phase at 18–30 km layer (I–II quarter) and in western QBO phase at 13–23 km layer (IV quarter). At separate layers it is revealed significant impacts of AO (II–III quarters), SA (I–II quarters) and VA (III–IV). During a year influence of PSC is originally showed in II quarter at 13–18 layer and then in IV quarter at 13–18 layer. Possible physical mechanisms are discussed which are the basis of the correlation relations observed.
Stability of the Vertical Distribution of Dust Aerosol in Light and Moderate Winds
Authors: Malinovskaya Е. A. , Chkhetiani O. G. , Golitsyn G. S. , Lebedev V. A.
Published: April 2024

The profiles of dust aerosol mass concentration obtained with multilevel (0.2, 0.4, 0.8, 1.6, and 3.2 m) daytime measurements in arid conditions in 2020–2022 show a power dependence on height. We distinguish three main types of changes in concentration with height: a) in low wind (degrees are close to –0.5); b) spike changes in concentration when wind increases (degrees reach and exceed –1); c) inversions (concentration increases with height at two or three lower levels of measurements): weak – about –20 mkg/cm3, significant – more than 50 mkg/cm3. The power dependence of –0.5 is explained by the collective effect of the rise of the ensemble of closely located bubbles of air warmed around the dust particles. In weak and moderate winds, this mode is more common. Burst changes in concentration are associated with the emergence of turbulent structures.
Variability of Extreme Air Temperatures and Precipitation in Different Natural Zones in Late XX and Early XXI Centuries According to ERA5 Reanalysis Data
Authors: Zheleznova I. V. , Gushchina D. Y.
Published: April 2024

Global temperature rise on the planet is accompanied by an increase in the frequency of extreme weather events, which can lead to significant disturbances in plant metabolic processes and the functioning of plant communities. Depending on the type of vegetation and climatic conditions, the extent and nature of this impact can vary significantly. Therefore, the aim of this work was to identify areas with different types of plant communities that have been most affected by extreme temperatures and precipitation in recent decades. To identify regions with temperature and precipitation extremes, we estimated the frequency of exceeding a given threshold (less than 5% quantile or greater than 95% quantile) for selected theoretical probability density functions for the air temperature and precipitation series. The number of cases of exceeding the extreme threshold is calculated for the whole globe, their spatial and temporal variability in different seasons of the year and in the first decades of the XXI century compared to the end of the XX century is analysed. The regions with different types of plant communities with the most pronounced amplification of extreme temperature and precipitation regimes under changing climate conditions were identified.
Anomalous Selective Absorption of Smoke Aerosol during Forest Fires in Alaska in July–August 2019
Authors: Gorchakov G. I. , Kopeikin V. M. , Gushchin R. A. , Karpov A. V. , Semoutnikova E. G. , Datsenko O. I. , Ponomareva T. Ya.
Published: April 2024

According to the monitoring data of the optical and microphysical characteristics of smoke aerosol at AERONET stations during forest fires in the summer of 2019 in Alaska, anomalous selective absorption of smoke aerosol was detected in the visible and near infrared spectral range from 440 to 1020 nm. With anomalous selective absorption, the imaginary part of the refractive index of smoke aerosol reached 0.315 at a wavelength of 1020 nm. A power-law approximation of the spectral dependence of the imaginary part of the refractive index with an exponent from 0.26 to 2.35 is proposed. It is shown that for anomalous selective absorption, power-law approximations of the spectral dependences of the aerosol optical extinction and absorption depths are applicable with an Angstrom exponent from 0.96 to 1.65 for the aerosol optical extinction depth and from 0.97 to –0.89 for the aerosol optical absorption depth, which reached 0.72. Single scattering albedo varied from 0.62 to 0.96. In the size distribution of smoke aerosol particles with anomalous selective absorption, the fine fraction of particles of condensation origin dominated. The similarity of the fraction of particles distinguished by anomalous selective absorption with the fraction of tar balls detected by electron microscopy in smoke aerosol, which, apparently, arise during the condensation of terpenes and their oxygen-containing derivatives, is noted.
Conditionally Background Level of Aerosol Pollution of Near-Surface Air in Moscow and One of Its Suburbs: Seasonal Variations
Authors: Gubanova D. P. , Vinogradova A. A. , Lezina E. A. , Iordanskii M. A. , Isakov A. A.
Published: April 2024

The data of continuous observations of aerosol composition in the near-surface atmosphere in Moscow (in the city center) and in Moscow region (near Zvenigorod, Moscow region) for three years, from autumn 2019 to the end of 2022, are analyzed. The obtained data were compared with the results of observations on the Moscow network stations “Mosecomonitoring”. The concept of conditionally background aerosol pollution of the atmosphere in Moscow is introduced for those days when the average daily concentration of PM10 is less than the MPC value (60 µg/m3). Previously, the authors found that all episodes of increased aerosol pollution in Moscow with daily average PM10 concentration higher than the MPC value, are associated either with the presence of a close local source in the city itself, or with the long-range transport of fire aerosols and/or dust from other territories to the Moscow region. The average daily PM2.5 concentration in the city and the suburb is lower than the MPC (35 µg/m3) all year round. The days corresponding to the introduced conditional background make up more than 91% over three years in the center of Moscow. Such a conditional background is formed by both natural and anthropogenic sources of aerosols, and not only of local, but also of remote origin. It implicitly takes into account the influence of meteorological conditions on sources and sinks of aerosols, as well as advective air mass transport of aerosol to and from the city. Seasonal variations in mass concentration of PM10, PM2.5 particles and individual chemical elements, as well as in the distribution of chemical elements by the size of aerosol particles in near-surface atmosphere under conditionally background pollution are analyzed. The emphasis is placed on the similarity and difference in the conditionally background near-surface aerosol for the city and the suburb in different seasons.
Explosive Growth of Asymmetric Disturbances in a Flow with Vertical Shear
Authors: Kalashnik М. V.
Published: April 2024

The classical problem of geophysical hydrodynamics is the problem of the instability of a zonal geostrophic flow with a vertical velocity shear. At present, the instability with respect to symmetric perturbations that do not depend on the coordinate along the flow has been most thoroughly studied. For a symmetric instability to arise, the two-dimensional perturbation wave vector must lie inside a certain sector in the vertical plane of the wave numbers. In this paper, we study the instability with respect to asymmetric perturbations oriented at an angle to the flow. Fundamentally new features of the temporal dynamics of the amplitudes of such perturbations are found. The main feature is associated with the existence of a stage of exponential explosive growth of finite duration. A kinematic interpretation of this stage is given, which is related to the passage of the vertical projection of the perturbation wave vector through the sector of symmetric instability.
Contributions of Nonlinear Spectral Components to the Probability Distribution of Rogue Waves Based on the Results of Numerical Simulation of the Euler Equations
Authors: Slunyaev A. V.
Published: April 2024

The contributions of various wave components (second, third and difference harmonics) to the formation of probability distributions of extreme wave heights, as well as amplitudes of crests and troughs, are evaluated based on the direct numerical simulation of irregular nonlinear deep water waves within three-dimensional potential equations of hydrodynamics. The simulation results taking into account 4- and 5-wave nonlinear interactions are analyzed. Different non-linear harmonics participate in the formation of the probability distributions in nontrivial way, essentially not satisfying the principles of linear superposition and ordering of the contribution by the parameter of weak nonlinearity.
On Turbulent Helicity in the Surface Layer of the Atmosphere
Authors: Solenaya О. А. , Shishov Е. А. , Chkhetiani О. G. , Azizyan G. V. , Koprov V. M.
Published: April 2024

Synchronous measurements of vorticity and velocity in the boundary layer of the atmosphere were carried out using the original 3-component acoustic circulator developed at the A.M. Obukhov Institute of Physical Physics in 2019–2020. The measurements were carried out in summer at the Tsimlyansk scientific station (in 2021, 2022) at altitudes of 1.75 and 30 m. For different realizations, turbulent helicity has negative values on average, which is possibly due to the presence of local (breeze) winds. The observed spectra of turbulent helicity exhibit a slope close to –5/3, which corresponds to the transfer of helicity along the spectrum towards small scales (direct cascade). Spectrum slopes of –4/3 are also observed, and in the low-frequency region – –1, associated with the convective component, wind shear, and submesoscale structures. The components of the turbulent vortex flow are calculated. The helicity values agree with the previously measured and theoretical estimates obtained for neutral conditions.
Estimation of Spatial Distribution of Potential Sources of Carbonaceous Aerosol from Local Measurements Near St. Petersburg
Authors: Vlasenko S. S. , Ivanova O. A. , Ryshkevich T. I. , Mikhailov E. F.
Published: April 2024

The results of back-trajectory analysis of nine-year (2013–2021) measurements of organic (OC) and elemental (EC) aerosol carbon concentrations made at the atmospheric monitoring station near St. Petersburg (Peterhof, 59.88° N, 29.83° E) are presented. The spatial location of sources was estimated by the concentration weighted trajectory method (CWT) in the geographic area 16°–44° E × 48°–68° N. The obtained data allow us to identify the territories with the strongest organic and elemental carbon emissions and to estimate the seasonal variability of these emissions. In particular, the obtained estimates show that the most intense sources of organic and elemental aerosol carbon in the studied region are located in the Volga-Oka interfluve and on the adjacent territories. It is demonstrated that linear regression coefficients between CWT function values for organic and elemental carbon differ for different regions and seasons and may indicate the prevailing type of sources of carbon-containing aerosol particles.
SEDIMENTATION OF TITANIUM DIOXIDE SUSPENSION UNDER THE ACTION OF MAGNETIC FLOCCULANTS
Authors: PROSKURINA V. E. , KASHINA E. S. , RAKHMATULLINA A. P.
Published: April 2024

Magnetic flocculants are synthesized from magnetite (Fe3O4) nanoparticles and ionic and nonionic acrylamide copolymers having different concentrations of ionic units and molecular weights. The synthesis is carried out in two steps: two magnetite samples having different size and surface characteristics are precipitated with ammonia from a mixed aqueous solution of Fe(II) and Fe(III) chlorides; then, the obtained samples are mixed with aqueous solutions of polyacrylamide flocculants. Individual particles of magnetite, copolymers, and magnetic flocculants based thereon are characterized by dynamic light scattering. Effect of the nature and flocculating ability of magnetic flocculants on the process of sedimentation of a titanium dioxide suspension is estimated. Varying the sizes of magnetic nanoparticles and the molecular parameters of acrylamide copolymers in the magnetic flocculant makes it possible to obtain a highly efficient multifunctional flocculant for the selective separation of multicomponent disperse systems.
VISCOELASTIC PROPERTIES OF FERROFLUIDS WITH CLUSTERED PARTICLES
Authors: CHIRIKOV D. N. , ZUBAREV A. YU.
Published: April 2024

Clustered (multi-core) magnetic fluids provoke a considerable interest of researchers and practitioners, because they are very promising for various technical and biomedical applications. These fluids contain clusters (clustered particles), which, in turn, consist of ferromagnetic nanoparticles retained together by a polymer shell. The typical size of a cluster varies from a few tens to several hundreds of nanometers, while the sizes of individual single-domain ferroparticles of which it is composed vary from 5 to 12 nm. The rheological phenomena in such fluids (strong magnetorheological effect and slow viscoelastic relaxation) are predetermined by the association of the clustered particles under the action of an external magnetic field into heterogeneous structures and aggregates and the dynamics and disruption of these aggregates in macroscopic deformational flows. In this work, we propose a theoretical model for viscoelastic effects in clustered magnetic fluids. The model is based on the idea of aggregating composite particles into linear chain-like aggregates. In the order of magnitude, the theoretical results agree with experimental data.
ACOUSTIC RADIATION OF CHARGED DROPLETS OSCILLATING IN THE SUPERPOSITION OF GRAVITATIONAL AND ELECTROSTATIC FIELDS
Authors: GRIGOR’EV A. I. , KOLBNEVA N. YU. , SHIRYAEVA S. O.
Published: April 2024

The intensity of acoustic radiation and the characteristic widths (depending on the radii and charges of the drops) of the frequency ranges in which the radiation falls have been calculated for charged droplets of convective clouds and near-ground fogs, which are immobile in the superposition of gravitational and electric fields. The calculations have been carried out using the methods of classical mathematical physics taking into account two small parameters: the dimensionless oscillation amplitude and the equilibrium spheroidal deformation of a charged droplet in an external electrostatic field. All calculations have been performed using the model of an ideal incompressible electroconducting liquid. It has turned out that the acoustic radiation from clouds and fogs occurs in the ultrasonic frequency range, while the acoustic radiation of large rain-drops is in the acoustic range audible to the human ear. The boundary between the ultrasonic and sonic radiations is determined by droplet sizes, electric field strengths (in a small vicinity of the droplets), and the values of interfacial tension coefficient.
REARRANGEMENTS IN THE CONFORMATIONAL STRUCTURE OF POLYELECTROLYTES ON THE SURFACE OF A FLATTENED METAL NANOSPHEROID IN AN ALTERNATING ELECTRIC FIELD
Authors: KRUCHININ N. YU. , KUCHERENKO M. G.
Published: April 2024

A mathematical model has been presented for the formation of the conformational structure of chain units in a polyelectrolyte adsorbed on a flattened conducting charged nanospheroid polarized in an external electric field, which harmonically varies at a frequency much lower than the plasma frequency of the nanospheroid metal. Molecular dynamics has been employed to study the rearrangements in the conformational structure of uniformly charged polypeptides adsorbed on the surface of the oppositely charged flattened gold nanospheroid in an external alternating electric field, the strength vector of which varies along the rotation axis of the nanospheroid. One-dimensional density distributions along the rotation axis, as well as radial distributions, have been plotted for atoms of the polypeptides adsorbed on the nanospheroid surface. At a low temperature, a narrow ring-shaped polyelectrolyte fringe is formed in the equatorial region of the flattened metal nanospheroid, and the fringe density increases with the total charge of the nanospheroid and the number of charged units in polyelectrolyte macrochains. At a high temperature, the formed narrow macromolecular ring periodically shifts along the rotation axis of the nanospheroid with redirections of the polarizing electric field vector. The amplitude of the shifts increases with a decrease in the total charge of the nanospheroid and an increase in the fraction of charged units in a polyelectrolyte.
THE EXPERIMENTAL STUDY OF EVAPORATION OF WATER AND NANOFLUID DROPLETS ON THE SURFACES OF MATERIALS WITH DIFFERENT THERMAL CONDUCTIVITIES
Authors: STERLYAGOV A. N. , NIZOVTSEV M. I.
Published: April 2024

The article presents the results of experimental studying evaporation of water and nanofluid droplets on the surfaces of various materials. Plates made of materials with significantly different thermal conductivity coefficients have been used as substrates: copper (λ = 401 W/m °С), Teflon (λ = 0.25 W/m °С), and extruded foamed polystyrene (λ = 0.03 W/m °С). In the experiments, the evaporation of water and nanofluid droplets with a volume of 5 μL has been considered at a constant temperature and humidity of the ambient air. A nanofluid (a mixture of water with gold nanoparticles) has been prepared by laser ablation. The concentration of nanoparticles in the nanofluid is about 0.1 wt %. Infrared thermography has been employed to determine the average temperatures of evaporating droplet surfaces. The results obtained have shown that, for all studied materials, the surface temperature of evaporating water droplets is higher than the temperature of adiabatic evaporation. Therewith, the lower the thermal conductivity coefficient of a substrate material, the lower the surface temperature of the droplet and the longer the time of its evaporation. The performed experiments have shown that the minimum temperature of nanofluid droplets is lower than that of water droplets, and the evaporation time of nanofluid droplets is longer than that of water droplets on the corresponding surfaces.
CAVITATION IN LIQUID METHANE WITH SMALL HELIUM ADDITIVES
Authors: BAIDAKOV V. G. , VINOGRADOV V. E.
Published: April 2024

Cavitation in a viscous gas-saturated liquid has been considered taking into account the diffusive supply of a volatile component to a bubble within the framework of the classical nucleation theory (CNT). An expression has been obtained for the steady-state flux of new phase nuclei. The method of simultaneous pulse stretching and heating has been employed to determine the limiting stretchings of pure methane and methane–helium solutions with helium contents of up to 0.2 mol %. The data obtained on nucleation rate of (1020–1022) m–3 s–1, have been compared with the results of calculations by the CNT. The peculiarities of new phase nucleation in weak solutions and the reasons for the discrepancy between the theoretical and experimental data have been discussed.
ANISOTROPY IN THE ADSORPTION OF H2O ON KAOLINITE SURFACES
Authors: KASPRZHITSKII A. S. , LAZORENKO G. I. , KRUGLIKOV A. A. , YAVNA V. A.
Published: April 2024

Adsorption capacities of kaolinite's edge and basal surfaces may differ. Тhese features determine the nature of its adsorption behavior while remaining poorly studied. At the same time, the anisotropy of the edge surface stipulates the wide application of kaolinite in geochemical, environmental, and technological fields. In this work, ab initio calculations have been employed to determine the effect of kaolinite surface anisotropy on its adsorption capacity. The mechanism has been studied for binding water molecules to the most stable kaolinite surfaces, namely, (001), (001¯), (010), and (110). It has been found that the most energetically advantageous adsorption configurations of water molecules arise on edge surface (010), with adsorption energy being ~four times higher than that on basal surface (001¯). The observed energy difference is due to the fact that hydroxyl groups are involved in the adsorption mechanism in addition to surface oxygen atoms. The absence of these groups on the basal surface significantly reduces the probability of hydrogen bonding. The results obtained are in agreement with the data from published studies.
CONTACT ANGLE HYSTERESIS ON SOLID CRYSTALLINE SURFACES
Authors: ESIPOVA N. E. , ITSKOV S. V. , SOBOLEV V. D.
Published: April 2024

The article presents the results of experimental studying the hysteresis of water contact angles at crystalline surfaces. Receding and advancing contact angles and their hysteresis at hydrophilic and hydrophobic substrates with different surface structures (silica, mica, and calcite) have been studied under the action of an external pressure applied to the three-phase contact line of a sessile air bubble. Hysteresis of the contact angles has been observed on hydrophobized samples of silica and mica. The anchoring of the three-phase contact line (pinning) facilitates a change in the contact angles under the applied external pressure. When the three-phase contact line moves along the hydrophilic surfaces of silica and mica no marked changes in the advancing and receding contact angles are observed, and the hysteresis is actually absent. The stable pinning observed on the polished surface of a calcite crystal brought in contact with water leads to the appearance of contact angle hysteresis and hydrophilization of the calcite surface, with the hydrophilization being related to structural displacements in the crystal lattice.
TRIC EXPLOSION OF AEROSOLS. TO THE 115TH ANNIVERSARY OF THE TUNGUSKA METEORITE
Authors: KIRSH A. A.
Published: April 2024

A hypothesis has been proposed according to which the preserved traces of the impact on the nature caused by the explosion of the Tunguska meteorite are the result of electrical discharges in a cloud of solid particles, which, when moving at the space velocity in the upper atmosphere, were heated up to a high temperature and, due to thermionic emission, acquired large positive charges. The released thermo-electrons attached to air molecules and lagged behind the charged particles. The separation of the charges in the cloud caused powerful discharges similar to horizontal lightnings in clouds. The consequences of the discharges in the cloud of highly charged solid particles, which gave rise to the generation of hard ionizing radiation, are discussed.
DEVELOPMENT OF CORE–SHELL STRUCTURES CAPABLE OF PH-RESPONSIVE RELEASE OF ENCAPSULATED COMPOUNDS
Authors: KUZNETSOV A. O. , VLASICHEVA YU. N. , LENGERT E. V. , ERMAKOV A. V.
Published: April 2024

Currently, the development of drug delivery systems is an important trend in modern biomedicine. During the last five years, a tendency is observed to complicate the developed carriers with the production of complex multicomponent carriers in order to improve the targeting and selectivity of their action. For this purpose, various properties characteristic for particular sites of a body are used, thus making it possible to specify the action of the carriers. One of the used factors is the medium pH, which is strictly regulated by an organism and is constant in a particular site of it. In this work, we develop an approach to the formation of complex core–shell particles based on mesoporous calcium carbonate particles and AMS-6 silica particles. The loading capacity of the obtained complex particles with respect to TRITC–BSA model dye and the kinetics of its release from them are studied. The carriers obtained in the work are promising to be used as drug carriers with pH-dependent release kinetics of encapsulated drugs.
INTERACTION OF PLATINUM NANOPARTICLES SYNTHESIZED ON GRAPHITE WITH NITROUS OXIDE
Authors: BAIMUKHAMBETOVA D. , GATIN A. K. , OZERIN S. A. , GRISHIN M. V.
Published: April 2024

Heterogeneous catalytic reactions involving nitrous oxide (N2O) are of great interest for medicine, technology, and ecology. The goal of this work is to determine the features of adsorption of N2O molecules followed by their interaction with a catalytic system based on metal nanoparticles at room temperature. Scanning tunneling microscopy and spectroscopy, as well as Auger spectroscopy, have been employed to identify the results and products of the adsorption of nitrous oxide on the surface of individual Pt nanoparticles synthesized on highly oriented pyrolytic graphite. It has been shown that, at short exposures, oxygen atomsresulting from dissociative adsorption oxidize the surface of nanoparticles only near the platinum–graphite interface. As the exposure increases, the entire surface of the nanoparticles is covered with oxide. Thus, it has been shown that the adsorption properties of the surface of the platinum nanoparticles on graphite are not the same, and this fact provides the possibility to carry out different chemical reactions on different surface regions, thereby increasing the efficiency of the catalytic system as a whole.
SYNTHESIS OF MONODISPERSE SILICA PARTICLES BY CONTROLLED REGROWTH
Authors: KHLEBTSOV B. N. , BUROV A. M.
Published: April 2024

The development of a simple and reproducible method for the synthesis of monodisperse silica particles is of considerable interest from the point of view of their numerous applications in photonics, biosensing, and biomedicine. When using the well-known Stober method, there is a continuous formation and growth of seeds, which leads to the synthesis of polydisperse colloids. In this work, we used the method of successive growth of silica particles obtained by hydrolytic condensation of tetraethylorthosilicate in an alcoholic-aqueous medium using an alkaline catalyst. It is shown that this technique makes it possible to obtain colloids with a particle size from 50 nm to 3 μm and a standard deviation of less than 5%. An additional advantage of the developed method of stepwise growth is the possibility to include fluorophores and SERS tags into the silica matrix.
EFFECT OF MAGNETITE CONTENT AND SPECIFICITY OF NICKEL(II) IONS ON ELECTROKINETIC PROPERTIES OF COMPOSITES BASED ON POROUS SILICA PARTICLES
Authors: VOLKOVA A. V. , LOPATINA E. S. , SOLOVYEVA E V. , ERMAKOVA L. E.
Published: April 2024

Powders of magnetite and its composites have been obtained on the basis of macroporous highsilica glass particles containing different amounts of Fe3O4. XRD, XPS, and Raman spectroscopy have been employed to confirm the formation of a magnetite phase in all iron-containing samples. The surface morphology and elemental composition of porous composite particles have been studied by SEM and EDX methods. It has been found that the external surface of porous silica particles is modified to different extents. It has been shown that the positions of the isoelectric point (IEP) and the values of the zeta-potentials for the composites coincide in indifferent electrolyte solutions. Two isoelectric points are observed in the pH dependences of the zeta-potential for the composite particles in nickel chloride solutions. In dilute solutions containing specifically adsorbed nickel ions and at pH values pHIEP-2, the electrokinetic properties of the composite particles are primarily affected by magnetite phase content in a composite powder and, at rather high concentrations of Ni2+ ions, by their specificity with respect to oxide surfaces.
STABILIZATION OF PICKERING EMULSIONS WITH HETEROAGGREGATES OF DETONATION NANODIAMONDS AND SIO2 NANOPARTICLES
Authors: PALAMARCHUK K. V. , PALAMARCHUK N. P. , BUKREEVA T. V.
Published: April 2024

The stabilization of Pickering emulsions with mixtures of similarly and oppositely charged detonation nanodiamonds and silica nanoparticles has been studied. Dynamic light scattering has been employed to study the influence of pH and the mass ratio of the particles on the sizes and ζ-potentials of aggregates. The formation of heteroaggregates from mixtures of similarly charged nanoparticles and the efficient stabilization of dodecane droplets have been shown and theoretically substantiated. Submicron droplets of Pickering emulsion stabilized with the mixtures of oppositely charged silica nanoparticles and detonation nanodiamondshave been obtained.
FEATURES OF BORIC ACID SORPTION BY FIBAN A-5 ANION-EXCHANGE FIBER UNDER STATIC CONDITIONS
Authors: BUTSKIKH E. A. , VORONYUK I. V. , ELISEEVA T. V. , MEDYAK G. V. , POLIKARPOV A. P.
Published: April 2024

Excessive contents of boron and its compounds can exhibit toxic effects despite their necessity for functioning living organisms. An urgent task is to remove them in various ways, including the use of sorption technologies. Boron-selective sorbents with functional OH groups and granular anion exchangers with functional amino groups are capable of extracting boron compounds. This paper is devoted to studying boric acid sorption under static conditions on FIBAN A-5 fibrous sorbent, which shows a high affinity for boron and can be used as an alternative to anion-exchange resins produced in the form of granules. The features of the kinetics and equilibrium of the sorption by the studied fiber brought in contact with boric acid solutions have been studied. It has been found that the time required to reach the equilibrium state decreases with the intensification of stirring and an increase in the concentration gradient in a solution. Sorption isotherms are of a stepwise character due to the existence of boron in different forms at concentrations above 0.025 M. The influence of temperature, pH of a solution, and ionic form of the sorbent on the capacity of FIBAN A-5 fiber has been determined.
CHARACTERIZATION OF SUPERHYDROPHOBIC COATINGS BASED ON PDMS AND MQ RESIN ON TEXTURED SURFACES
Authors: DENMAN N. , EMEL’YANENKO A. M. , O. A. SERENKO O. A. , BOINOVICH L. B.
Published: April 2024

The paper presents the results of studying coatings based on poly(dimethylsiloxane) rubber crosslinked with MQ resin at different contents of the latter. The PDMS :MQ resin ratios have been taken to be 2 : 1, 1 : 1, and 1 : 2. It has been shown that the application of a hydrophobic fluorinated-group-free composite with composition PDMS :MQ = 1 : 1 onto a pre-textured surface by spin-coating or deep-coating results in the formation of superhydrophobic coatings. The coatings are characterized by extremely large contact angles (170°) and rolling angles no larger than 4°. The analysis of variations in the contact angle, surface tension, and contact diameter and volume of a water droplet that has been in contact with a coating for a long time has indicated a high hydrolytic resistance of the obtained coatings.
Lecithin Microemulsions as Drug Carriers
Authors: Murashova N. M.
Published: April 2024

The paper describes examples of microemulsions based on a well-known biocompatible surfactant, lecithin, and the possibilities of their use as drug carriers. The main problem encountered when developing lecithin microemulsions is the search for suitable cosurfactants. Molecules with short alkyl chains (4–5 C atoms) and relatively large polar “head,” such as short-chain aliphatic alcohols, acids, and amines are most suitable as cosurfactants for the preparation of lecithin microemulsions. Therewith, high concentrations of the cosurfactants (the cosurfactant : lecithin weight ratio usually is 1 : 1) are necessary. Most often, ethanol, n-propanol, or n-butanol are used as cosurfactants for the preparation of lecithin microemulsions in various natural and synthetic oils. To replace toxic alcohols with less toxic components, other well-known surfactants may be added to lecithin microemulsions. They are, e.g., Brij 96V (poly(ethylene glycol) oleate), Tween 80 (polyoxyethylene-20-sorbitan monooleate), Tween 20 (polyoxyethylene-20-sorbitan monolaurate). Triton X-100 (tert-octylphenyl ether of poly(ethylene glycol)) or oleic acid. Composites based on lecithin microemulsions have been described as means for local anesthesia and delivery of vitamins, as well as agents with anti-inflammatory, antifungal, anticancer, and wound healing effects. The considered examples show the promise of the study and development of lecithin microemulsions as drug carriers.
Impact of the Aging of Ultrasmall Gold Nanoparticles on their Interaction with Cholesteric DNA Microparticles
Authors: Klimovich M. A. , Kolyvanova M. A. , Dement’eva O. V. , Klimovich O. N. , Rudoy V. M. , Kuzmin V. A. , Morozov V. N.
Published: April 2024

The correlation between the time of preliminary storage of ultrasmall gold nanoparticles (GNPs) synthesized according to the Duff method and the structural aspects of their interaction with the particles of cholesteric liquid-crystalline dispersions (CLCDs) of DNA were studied. It has been established that the “age” of GNPs significantly affects the magnitude of their destructive action on the ordered organization of the DNA CLCD particles. The observed effect may be caused by both the gradual perfecting of the crystal lattice of the studied GNPs (i.e., their metallization) and the change in the chemistry of their surface over time.
Nanoemulsions and Solid Lipid Nanoparticles with Encapsulated Doxorubicin and Thymoquinone
Authors: Mishchenko E. V. , Gileva A. M. , Markvicheva E. A. , Koroleva M. Yu.
Published: April 2024

Nanoemulsions (NEs) and solid lipid nanoparticles (SLNs) are promising drug delivery systems. In this work, paraffin oil NEs and stearic acid SLNs stabilized with Tween 60 and Span 60 have been studied. NEs with an average droplet diameter of ~50 nm and suspensions of SLNs with an average size of ~30 nm are stable to aggregation for more than 90 days. The rates of penetration of lipid particles into cancer cells (C6 and MCF-7) depend on their sizes. After incubation for 1 h, lipid nanoparticles ~50 nm in size penetrate into cells, are distributed in their internal space, and concentrate in the nuclei. The cytotoxicity of doxorubicin- or thymoquinone-loaded NEs and SLNs against MCF-7 and HTC 116 cell lines is higher than the cytotoxicity of the individual substances. Wherein, unloaded NEs and SLNs show low cytotoxicity. The obtained results demonstrate that paraffin oil NEs and stearic acid SLNs are promising to be used as carriers of both lipophilic and amphiphilic drugs, including doxorubicin and thymoquinone. The accumulation of lipid nanoparticles with sizes smaller than 100 nm in cell nuclei is an advantage of such systems for the delivery of anticancer drugs, because this leads to DNA replication suppression followed by cell apoptosis.
Stimuli-Responsive Drug Delivery Systems Based on Bilayer Lipid Vesicles: New Trends
Authors: Efimova A. A. , Sybachin A. V.
Published: April 2024

The development of new efficient methods for combating serious diseases, among which, oncological and infectious diseases hold a special place, remains to be an urgent challenge of biomedicine and biotechnology. Currently, the efforts of scientists are focused on the search for drug systems that provide high efficiency of treatment with minimal impacts on a human body. The development of this field has led to the creation of stimuli-responsive liposomes that can release an encapsulated drug under a specific stimulus, such as temperature, pH, electromagnetic field, light, etc. Being stimulated, lipid bilayer vesicles change their structure, size, surface charge, or phase state, thus leading to a controlled release of the drug in a specific place of the body, thereby resulting in a more accurate and efficient delivery. This review discusses the current trends in the development of liposome-based stimuli-responsive systems for the controlled delivery of biologically active substances.