bluuebunny/crossref_metadata_2025 huggingface dataset:
Geochemical Criteria for the Classification of Dolerite Dikes in the Central Part of the Baikal Basement Inlier of the Siberian Craton
Authors: Donskaya T. V. , Gladkochub D. P. , Mazukabzov A. M. , Demonterova E. I. , Efremova U. S.
Published: April 2024

The paper presents detailed geological, petrographic, geochemical, and isotope data on the dolerites from dykes of the Baikal dike subswarm in the central part of the Baikal basement inlier of the Siberian craton. The main geochemical and isotope criteria were identified for classifying the dolerites that are similar in geological–structural position and mineral composition into three geochemical groups. Provisional age estimates of the dolerites are presented. The dolerites of the first and, perhaps, second groups compose Neoproterozoic (715 Ma) dikes. The first group includes medium- to coarse-grained dolerites, which form thick (more than 5–10 m) dikes. The dolerites of this group are characterized by low concentrations of Th (0.6–2.1 ppm) and Nb (3.3–9.2 ppm) and by ɛNd(T) = ‒0.5 to ‒3.9. Considered together, the geochemical and isotope data show that these dolerites could be produced as a result of the melting of a mantle source produced by mixing mantle components close in composition to oceanic plateau basalts and subduction-related subcontinental lithospheric mantle. The second group includes fine-grained dolerites from thin (1–5 m) dikes, including dikes located in contact with the dikes of the first group. The dolerites of the second group are characterized by higher concentrations of Th (3.0–5.3 ppm) and Nb (9.8–21.1 ppm) and by ɛNd(T) = –5.3 to ‒6.0. Geochemical and isotopic data on the dolerites of the second group indicate that continental crustal material was added to the mantle source unified for the dolerites of first and second groups. The third group includes medium-grained dolerites, which make up individual dikes that are contrastingly different in geochemical and isotope characteristics from the Neoproterozoic dolerites of the first and second groups. Dolerites of this group show low concentrations of Th (0.6–1.6 ppm) and Nb (2.7–5.1 ppm) at low values of (Th/La)pm (0.29–0.71) and 143Nd/144Nd (0.511223‒0.511544), which indicates that these dolerites may have been generated as a result of the melting of the subcontinental lithospheric mantle enriched in subduction components. Dolerites of the third group exhibit geochemical characteristics close to those of Paleoproterozoic (1.84 Ga) dikes of the South Siberian post-collisional magmatic belt.
Geochemistry of Trace Elements in Minerals of Porphyritic and Nonporphyritic Chondrules from Equilibrated Ordinary Chondrites
Authors: Sukhanova K. G. , Skublov S. G. , Galankina O. L. , Obolonskaya E. V. , Kotova E. L.
Published: April 2024

The paper presents the results of SIMS and EPMA studies of silicate minerals and bulk compositions (SEM-EDS) of porphyritic and nonporphyritic chondrules from equilibrated ordinary chondrites. The trace-element distribution in olivine, low-Ca pyroxene, and mesostasis of porphyritic and nonporphyritic chondrules in the equilibrated ordinary chondrites reflects heterogeneous conditions of chondrule-forming processes in the protoplanetary disk and provides insight in their evolution. The porphyritic chondrules are composed of olivine with the low content of Y and Yb relative to nonporphyritic chondrules. The enrichment of low-Ca pyroxene from porphyritic chondrules in trace elements correlates with the amount of pyroxene in the chondrule. Olivine composition in granular chondrules is close to that of porphyritic chondrules, but low-Ca pyroxene is distinguished by the high content of Y, Ti, Sr, Ba, V, and REE compared to all other chondrules. Barred chondrules are characterized by olivine enriched in trace elements (Zr, Y, Ti, Ba, Cr, and HREE) and low-Ca pyroxene highly depleted in trace elements (Zr, Y, Nb). The pyroxene of radial chondrules is enriched in Nb, Sr, and Ba. Trace elements in olivine and low-Ca pyroxene indicate the formation of the porphyritic and granular chondrules in a stable region of the protoplanetary disk, which is responsible for low-temperature heating and slow cooling of a chondrule. Trace element enrichment of olivine from the barred chondrules testifies strong heating of a precursor material and rapid cooling of the chondrule melt. Mineral composition of radial chondrules demonstrate rapid cooling of a low-temperature melt depleted in Mg and trace elements. High melt temperatures of barred chondrules and rapid cooling of nonporphyritic chondrules indicate their formation in an unstable region of the protoplanetary disk. Trace elements in silicate minerals of porphyritic and nonporphyritic chondrules reflect their formation as a result of melting of precursor minerals.
Heavy Metals and Organic Carbon in the Bottom Sediments of Shallow Bights of the Peter the Great Bay
Authors: Ryumina A. A. , Tishchenko P. Ya. , Shkirnikova E. M.
Published: April 2024

A noticeable feature of labile heavy metals is that they are highly prone to be to bioaccumulated and bioassimilated in natural environments. When in high concentrations, these metals are toxic to living organisms, as is particularly evident in the coastal shallow marine zones, which are most strongly affected by anthropogenic processes. This paper presents data on the contents of heavy metals, concentrations of organic carbon, and the granulometric composition of bottom-sediment cores in three shallow bights of the Peter the Great Bay, in two of which (Voevoda and Novgorodskaya bights), large bottom areas are overgrown with seagrass Zostera marina L. (sea zostera, ZM). Data on the vertical distribution of heavy metals and organic carbon in the cores showed that the highest concentrations of Zn and Cu (up to 204 and 91 mg/kg, respectively) occur in samples from Voevoda bight, and the highest concentrations of Mn and Pb (up to 344 and 45 mg/kg, respectively) were found in Novgorodskaya bight, where meadows of the seagrass grow. The highest Cr, Ni, and Co contents (up to 69, 31, and 13 mg/kg, respectively) were identified in Uglovoy bight, where sea grass is practically absent.
Equation for Calculation of Saturated Water Contents in Silicate Melts: New Version
Authors: Gnuchev Ya. Yu. , Bychkov D. A. , Koptev-Dvornikov E. V.
Published: April 2024

On the basis of literature sources, a sample of experimental data was formed. The sample contains the results of 394 hardening experiments characterizing the saturated water content in a wide range of intensive parameters of silicate systems. An analysis of the main published types of models of water solubility in a silicate melt showed that the equation of Gordon Moore et al. best describes the experimental results.The Moore equation, converted to exponential form, is recalibrated on an extended experimental sample. As a result, new coefficients for this equation are obtained: a = 918; bAl2O3 = – 0.712; bFeO = – 0.749; bNa2O = 0.806; c = 1.087; d = -11.45. The Moore equation with new coefficients makes it possible, with an error not exceeding ±1 - ±2 relative percent, to predict the saturated water content in silicate melts in the range: melt compositions from basalts to rhyolites; pressure from atmospheric to 15 kbar; temperatures from 550 to 1300 °C.
GEOCHEMISTRY OF HIGH-PHOSPHORUS ZIRCON FROM THE UPPER RIPHEAN METASANDSTONES OF THE SOUTHERN TIMAN
Authors: Grakova O. V. , Skublov S. G. , Nikulova N. Yu. , Galankina O. L.
Published: April 2024

A detailed mineralogical and geochemical study (using the EPMA and SIMS methods) of zircon from metasandstones of the Dzhezhim Formation in the South Timan made it possible to establish an anomalously high content of phosphorus in it (up to 10.27 wt % P2O5 according to EPMA data), which correlates with an increased content of other non-formula admixture elements, the main of which are Y, REE, Ca, Fe, Al, Ti, Sr, Ba, Th, U. Of particular note is the significant amount of volatile components in zircon (up to 0.49 wt % water and up to 0.26 wt.% fluorine, determined by the method SIMS). The total content of non-formula admixture elements can exceed 20 wt %, which is a characteristic feature of the composition of zircon exposed to fluid or formed as a result of hydrothermal-metasomatic processes. The main mechanism for the incorporation of admixture elements into the composition of zircon was xenotime-type heterovalent isomorphism, when the presence of quinquevalent phosphorus is compensated by the participation of trivalent Y and REE. Of subordinate importance was the isomorphism scheme, which ensures the entry of hydrogen (water). The areas of zircon enriched in phosphorus and other adulterants are confined to the edge of the grains, or to systems of scissures and fluid-permeable areas. Granitoids served as a possible source of zircon, and the process of transformation of its composition (recrystallization and enrichment of local areas, less often whole grains) probably occurred already in the sandstone sequence, during metamorphism and/or hydrothermal process.
Development Vernadsky’ works on natural waters: biosphere processes and water quality
Authors: Moiseenko T. I.
Published: April 2024

The article considers the increasing of anthropogenic loads on surface waters. An analysis of the works of V.I. Vernadsky about natural waters and their importance in assessing modern biogeochemical processes. The scales of the input of elements and substances into the modern biosphere, such as the emission of greenhouse gases, the dispersion of nitrogen and phosphorus, acid-forming gases, as well as metals, are shown. Key changes covering regions and the biosphere as a whole are noted. Examples of the consequences of the development of anthropogenically induced processes in surface waters are given on the example of Arctic remote regions - the Kola North of Russia: the impact of climate warming, acidification, eutrophication and enrichment of waters with metals. Within the concept of V.I. Vernadsky about the role of natural waters in the life support of Planet population, approaches to assessing the quality of waters from the standpoint of the ecological paradigm are given.
Isotopic (δ13C, δ18O) Analysis of Small Amounts of Carbonate in Silicate Rocks by the Continuous Flow Isotope Ratio Mass Spectrometry Method
Authors: Dubinina E. O. , Chizhova Yu. N. , Kossova S. A.
Published: April 2024

An experimental study of the main factors affecting the accuracy of oxygen and carbon isotopic analysis in carbonates dispersed in silicate matrix is carried out. Artificial 1, 2, 5, and 10% mixtures of quartz with carbonates with different isotopic parameters (KH-2, Ko, MCA-8) were analyzed by continuous flow isotope ratio mass spectrometry (CF IRMS). It is established that, in addition to the influence of the instrumental nonlinearity, the results are affected by two factors: trace amounts of CO2, constantly present in the system (the blank effect) and the presence of chemically neutral silicate particles (the matrix effect). The blank effect depends on the isotopic parameters of the sample and has very little influence on the estimated carbonate content in the rock. The matrix effect, on the contrary, strongly affects the estimated carbonate content, and produces the isotopic shift towards underestimated contents of heavy 13C and 18O isotopes. It is shown that this effect is related to the processes occurring near the CO2–acid–quartz interface, which are accompanied by kinetic fractionation of carbon and oxygen isotopes. Both effects are dependent on the amount of silicate matrix in the system and most clearly manifested during analysis of carbonate-poor rocks. When the carbonate content in the rock is about 1–2%, deviations from the true δ13C and δ18O values can reach the first ppm, while carbonate content obtained by chromatographic peak calibration can be underestimated by 20–40%.
On the Lithogeochemical Reconstruction of Possible “Geodynamic” Types of Granites-Sources of Arkose Clastic Material
Authors: Maslov A. V. , Podkovyrov V. N.
Published: April 2024

A number of examples are considered in which modern arkose sands as well as arkose and compositionally similar sandstones (all of the above rocks are sediments of the first sedimentation cycle) of different ages have definite provenances composed of granitoids of different “geodynamic” types. The main goal of the work is to analyze how the geochemical characteristics of granitoids are translated into petrogenic sedimentary rocks. The comparison of 245 analyses of sands and sandstones with ~375 analyses of the inferred prototype sources of clastic material showed that the lithogeochemical characteristics of arkose and subarkose sands and sandstones (mainly the HFS element content and ratio) makes it possible in most cases to confidently judge the “geodynamic nature” of source felsic igneous rocks.
Evolution of Rare-Metal Li–F Granite Melts in Sources of Ore-Magmatic Systems of Tigrinoe and Zabytoe Sn–W deposits (Central Sikhote-Alin, Primorye)
Authors: Gavryushkina O. A. , Sokolova E. N. , Smirnov S. Z. , Kruk N. N. , Ponomarchuk A. V. , Tomas V. G.
Published: April 2024

The present paper considers petrographic and geochemical features of rocks of the Tigrinoe and Zabytoe stocks, provides their mineral composition, the results of the detailed study of micas and mineral-forming inclusions in quartz. It is shown that the development of ore-magmatic systems (OMSs) of the Zabytoe and Tigrinoe deposits is associated with the same rare-metal Li–F melts. It is confirmed that granitoids of the Tigrinoe stock can be considered as more differentiated analogs of granitoids of the Zabytoe stock. New data concerning the differences in the history of the magmatic stage of development of the OMSs of these deposits are presented. The evolution of melts of both deposits took place at high fluid pressure. Differences in the scale of ore mineralization of the two RMSs under consideration could be due to different fluid regime of magmatic sources evolution and more significant participation of transmagmatic fluid flows in the development of the Tigrinoe OMS.
A Plasma Pressure Plateau in the Night Sector
of the Earth’s Magnetosphere and Its Stability
Authors: Kirpichev I. P. , Antonova E. E.
Published: April 2024

In this paper, we consider the behavior of the radial distribution of the plasma pressure, magneticfield, and plasma parameter in the night sector of the Earth’s magnetosphere at geocentric distances from 7to 12 RE that are obtained using the THEMIS mission measurements. The results of measurements on theTHEMIS-D and THEMIS-A satellites on February 2009 when the satellites were near the equatorial planewere analyzed. Time intervals are identified when the plasma pressure actually did not change with a changein the distance from the Earth. It is shown that profiles with a pressure plateau can exist stably during the dayare destroyed during the period of disturbance and are restored after destruction. The role of the pressure plateauin the formation of the structure of magnetospheric current systems is discussed
The Spatio-Temporal Features of Pc1 Structured Geomagnetic Pulsations
Authors: Klain B. I. , Kurazhkovskaya N. A.
Published: April 2024

The results of a study of the spatio-temporal features and interplanetary conditions for the excitationof structured geomagnetic pulsations in the range Pc1 (“pearls”) are presented. For the analysis, weused simultaneous dynamic spectra of ultra-low-frequency oscillations in the frequency range 0.2–5.0 Hzobtained from digital data with high resolution of synchronous observations at two mid-latitude Borok observatories(BOX, Φ' = 53.6°; Λ' = 114.4°; L = 2.8) and Mondy (MND, Φ' = 47°; Λ' = 174°; L = 2.1) for theperiod from 1996 to 2001. During the analyzed period, 108 coherent series of “pearls” were selected at twoobservatories. It was found that the series of Pc1 pulsations were observed at the Borok observatory in relationto the Mondy observatory simultaneously (19% of cases), later (54% of cases), and earlier (27% of cases). Itis shown that the time intervals of the effects of later arrival and advance of the onset of pearls in BOX withrespect to MND were predominantly 10 and 20 min, respectively. Significant differences were found in thediurnal variation in the number of cases of Pc1 pulsations and geophysical conditions under which the Pc1series are excited simultaneously, or later or earlier to BOX in relation to MND. The detected effects of westernand eastern drift of the Pc1 series may be due to the position of the oscillation source relative to the plasmapause,depending on the interplanetary conditions
Aeronomic and Dynamic Correction of the Global Model GTEC
for Disturbed Conditions
Authors: Shubin V. N. , Gulyaeva T. L. , Deminov M. G.
Published: April 2024

An aeronomic and dynamic correction of the GTEC median global model of the total electroncontent for disturbed conditions (Ap ≥ 15 nT) is proposed. The GTEC global median model is developedfor quiet conditions (Ap 15 nT) as a function of the geographic coordinates, universal time UT, day of theyear, and solar activity level (the solar radio emission flux F10.7). The model is based on a spherical harmonicanalysis of the GIM-TEC Global Ionospheric Maps (1996–2019) provided by the Jet PropulsionLaboratory (NASA). The proposed GDMTEC global dynamic model (Global Dynamic Model of TEC)consists of the GTEC median model updated with several dynamic and aeronomic corrections related toformation of the main ionospheric trough, position of the auroral ionization maximum and changes of thethermospheric temperature and composition. The advantage of the proposed corrections of the medianmodel is the independence of forecast of the data in real time from assimilation of the current observationaldata. Testing of the model for disturbed conditions shows an improvement of the forecast compared to theIRI-Plas ionospheric reference model
Influence of the Gleissberg Cycle on Variations
of the 11-Year Cycle of Solar Activity in 1700–2021
Authors: Ptitsyna N. G. , Demina I. M.
Published: April 2024

The wavelet analysis was used to study the spectral composition of the sunspot numbers SN during1700–2021. In addition to the dominant 11-year component, two powerful components of the Gleissbergcycle can be traced in the spectrum: before 1880, a branch with a period of ~60 years; from 1850 a branch of~115 years is found. It is found that the series of lengths and amplitudes of the solar cycle as a whole areinversely related (correlation coefficient k = –0.5–0.63). The interval between the series at which the maximumanticorrelation is reached depends on time. In the 18th and early 19th centuries, the lag was equal toone cycle, in the 19th century it was two cycles, and from 1950 to our time the lag decreased to 2 years. Quasiperiodicstructures, which are typical for long periods of low solar activity, have been identified. Such a spectralfeature in ~1800 (Dalton minimum) was caused by the influence of the 60-year branch, while the onethat has been forming since the beginning of the 21st century is due to the weaker influence of the circa-centenarybranch. Therefore, it should be expected that the next solar cycles will be higher and shorter thanduring the period of the Dalton minimum. It has been shown that solar cycle length variations for the last321 years can be described within the framework of the model, which is an 11-year oscillation that is subjectto frequency modulation by the branches of the Gleisberg cycle (60 and 115 years) with time-varying influencesof the modulator
Features of Radio Signal Propagation in the VLF Range at High Latitudes
during Solar Proton Events
Authors: Akhmetov O. I. , Mingalev I. V. , Mingalev O. V. , Belakhovsky V. B. , Suvorova Z. V.
Published: April 2024

In this paper, we study the amplitude and phase characteristics of VLF signals of an anthropogenicorigin during solar proton events using the methods of a computational experiment. We consider the events ofOctober 30, 2003 and January 23, 2012. Electron density profiles are plotted using data from the VHF EISCATincoherent scatter radar located in Tromsø, Norway. Based on the processed data of computational experiments,that under the conditions of solar proton events, mainly amplitude distortions of VLF signals wereshown to be observed while there is a frequency dependence of the magnitude of distortions of the signals ofthe RSDN-20 long-range navigation radio system. The signal phases of the RSDN-20 system are less affectedby weak solar proton events. The effect of the lower boundary of the Earth-ionosphere waveguide in the casesof propagation of signals from the RSDN-20 system over the surface of land and ocean during a solar protonevent was studied.
Quartz Devices and Magnetovariation Stations: The History of the Development and Application
in Scientific Research (On the 95th Anniversary of V.N. Bobrov, a Legend of Quartz Magnetic
Instrumentation from IZMIRAN) (A Review)
Authors: Lyubimov V. V.
Published: April 2024

Abstract—IZMIRAN is currently the only organization in Russia that develops and manufactures high-precisionequipment based on quartz magnetic sensors for recording and studying geomagnetic variations. Magneticobservatories and many observation points in Russia, as well as foreign observatories, are equipped withthese instruments. The history of the development of quartz magnetometric instrumentation at the institutefrom the day of its foundation to the present day has been shown: from analog to modern digital instruments.
Disturbances in the Magnetosphere and Ionosphere
during Spotless Sun
Authors: Gulyaeva T. L.
Published: April 2024

Analysis of geomagnetic and ionospheric activity is performed for 541 disturbed days during spotlessSun (Kp 3.0) from 1995 to 2021. Variations of the global ionospheric indices WU (positive disturbancesof total electron content), WL (negative disturbances), their range WE and the planetary index Wp are analyzed.The source W-index characterizes a measure of deviation of the instant total electron content from thequiet median varying from −4 to +4 with a step 1, and the global indices WU, WL, WE, Wp are derived fromthe global maps GIM-TEC of Jet Propulsion Laboratory, JPL. Investigation of the seasonal dependence hasrevealed two levels of the ionosphere disturbances: the low disturbance of the ionosphere during 1996‒1998and 2018‒2021 and the high disturbance during 2004‒2010 and 2016‒2017. The seasonal ionosphere variationsare different for two sets of the data. The seasonal variations of the solar wind velocity Vsw near the Earthorbit are first identified for the 1st data set displaying the peaks at the equinoxes similar to variations of theKp-index. The 2nd set of the high disturbance of the ionosphere refers to the epoch of transition from the highsolar activity SA to low SA characterized by the total restructuring of the physical conditions on the Sun
Trends in the Critical Frequency of the F2 Layer during the Recent Decade
Authors: Danilov A. D. , Berbeneva N. A.
Published: April 2024

Trends in the F2-layer critical frequency foF2 are calculated based on the vertical sounding data atJuliusruh station over a period of 1996–2022. Four solar activity indices: Ly-α, MgII, F10.7mon, and Rz wereused. The conclusion drawn previously is confirmed: seasonal (stronger in winter than in summer) and diurnal(stronger in the daytime than at night) variations exist in the foF2 negative trends. It is shown that theresults for the first three indices agree very well, whereas the results using Rz provide slightly different results.It has been found that during the recent 5–7 years, the maximum (winter, daytime) negative trends in foF2became stronger than for the entire considered interval by a factor of 2–3
Global Ionospheric Response to Intense Variations
of Solar and Geomagnetic Activity According to the Data
of the GNSS Global Networks of Navigation Receivers
Authors: Pulinets M. S. , Budnikov P. A. , Pulinets S. A.
Published: April 2024

The global response of the ionosphere to intense geomagnetic storms and variations of the solaractivity according to the solar flux F10.7 is considered. As a source of information, data on total electron content(TEC) calculated from measurements of the global network of receivers of the global navigation satellitesystems are used. Unlike many publications, where the effects of individual unique geophysical events arestudied in detail (for example, the superstorm of October 28, 2003), we considered the effects of strong storms(Dst ≤ –80 nT) starting from 2005. The main attention was paid to the dependence on the onset time of themain phase of the storm relative to local time/longitude, as well as the dependence of the intensity of the ionosphericresponse on latitude. To display the ionospheric effects of magnetic storms, a visual image was used – atwo-dimensional representation in the day-local time format, which was used to visualize ionospheric earthquakeprecursors. This approach also makes it possible to visualize the effects of solar activity variations accordingto the F10.7 index and to distinguish them from ionospheric variations during geomagnetic storms. As aresult, it was possible to create a generalized global “pattern” of a geomagnetic storm in the Earth’s ionosphere
Statistical Studies of Auroral Activity and Perturbations
of the Geomagnetic Field at Middle Latitudes
R.
Authors: Werner R. , Guineva V. , Despirak I. V. , Lubchich A. A. , Setsko P. V. , Atanassov A. , Bojilova R. , Raykova L. , Valev D.
Published: April 2024

In this paper, we statistically analyzed substorm activity at auroral latitudes for 2007–2020 and itsrelationship with magnetic disturbances at middle latitudes using the INTERMAGNET, SuperMAG, andIMAGE magnetometer data. The appearance and development of magnetic disturbances at auroral latitudeswas monitored by the IL index (similar to the AL index, but calculated according to IMAGE data). For the2007–2020 period, events that were observed near the meridian of the IMAGE network, in the night sector(2103 MLT), were selected. Two samples of events were used: (1) IL –200 nT for at least 10 min, with anadditional criterion for the presence or absence of positive bays at the Panagyurishte station in Bulgaria, and(2) isolated substorms observed on the IMAGE meridian according to the list of Ohtani and Gjerloev (2020).The distributions of the IL index, as well as the empirical and theoretical cumulative distribution functions,are obtained, and the of the occurrence of extreme events are also estimated. It is shown that, in general, theIL distributions are described well by exponential functions, and out of all events, events accompanied bymid-latitude positive bays were observed in ~65% of cases while their fraction increased with increasing disturbanceintensity. Events with positive bays at midlatitudes of MPB and isolated substorms were betterdescribed by the Weibull distribution for extreme events. From both distributions, annual and semi-annualvariations were identified: annual variations have a summer minimum and a winter maximum, and semiannualvariations have maxima near the equinoxes, which is most likely due to the Russell-McPherron effect.The semi-annual variation is also shown to be more pronounced for events with accompanying mid-latitudinalpositive bays.
Coastal Effect in the Horizontal Components of the Electric Field
Authors: Ismagilov V. S. , Kopytenko Yu. A. , Petrishchev M. S. , Sergushin P. A. , Petlenko A. V.
Published: April 2024

The results of experimental studies of electric field disturbances generated by sources of an ionosphericorigin in the coastal zones of the White and Barents seas are presented. The data recording was performedby geophysical stations GI-MTS-1. The horizontal electric field was recorded by telluric lines ~50 mlong. The Ex component was set orthogonally to the coastline in the direction from the shore, and the Еycomponent was directed along the coastline. In the coastal strip of the sea–land contact, a zone of anomalousincrease in the amplitude of ULF variations (F 1 Hz) of the Ex component adjacent to the water’s edge wasrevealed. An additional narrow zone of anomalous amplification of the ULF variations of the electric field isobserved at a distance of ~30 m from the water’s edge. The coastal effect reaches its maximum near thewater’s edge in the coastal zone and decreases with distance from the seashore
An Empirical Model for Estimating the Velocities and Delays
of Interplanetary Coronal Mass Ejections
Authors: Shlyk N. S. , Belov A. V. , Abunina M. A. , Abunin A. A.
Published: April 2024

We studied the behavior of the interplanetary coronal mass ejection velocity as a function of thesource heliolongitude (associated solar flare), initial ejection velocity, and background solar wind velocity.The modeling is based on data on 364 ejections of solar matter accompanied by flares observed in theSOHO/LASCO coronograph, whose interplanetary analogues were subsequently recorded near the Earth inthe period from 1995 to 2021. A model is described that makes it possible to estimate the transit and maximumvelocities of the corresponding interplanetary disturbance, as well as the time of its arrival to the Earth. Theaverage absolute error in estimating the propagation time of interplanetary coronal mass ejections for the considered364 events is 11.5 h, and the average relative error is 16.5%.
Nanoflash Distribution at the Solar Minimum
Authors: Bogachev S. A.
Published: April 2024

We use data from the Atmospheric Imaging Assembly (AIA) telescope on the Solar DynamicsObservatory (SDO) spacecraft in the 171 Å channel to investigate the spatial distribution of low-energyflares (nanoflashes). We have studied two periods: 05/20/2019 from 1200 UT to 1300 UT and 05/10/2020from 1200 UT to 1300 UT. In total, we found 87974 nanoflares with an average formation rate of 6.0 ×10‒21 cm–2 s–1. For solar latitudes from 0° up to 50° the nanoflare formation rate is approximately uniformwith a standard deviation of about 25%. We have found an asymmetry in the rate of formation of nanoflaresin the southern and northern hemispheres of the Sun: the rate of formation of nanoflares in the southernhemisphere was 34–42% higher than in the northern one. During this period, the same asymmetry wasalso observed for ordinary f lares. We also found a weak dependence of the nanof lare formation rate on thesolar cycle: the number of nanof lares increases with higher solar activity.
Equatorial Plasma Bubbles: Zonal Thermosphere Wind Influence
Authors: Sidorova L. N.
Published: April 2024

There are a number of the theoretical studies pointing to the key role of the zonal thermosphere winds in the equatorial plasma bubble (EPB) generation and evolution. However, there are insufficient observational data to confirm the relationship between these phenomena. To study this relationship, the detailed comparative and correlation analysis of the LT-variations of the EPB occurrence probability and the zonal thermosphere wind velocity was carried out. The data from the EPB observations recorded aboard the ISS-b satellite (~972–1220 km) during the solstice and equinox periods were used. The data from the zonal thermosphere wind velocity observations obtained aboard the CHAMP satellite (~380–450 km) were also used. It was found that these characteristics are similar, when they are compared, and have very strong correlation (R 0.9) in summer, strong correlation (R 0.8) in winter and (R 0.79) at equinox. It was found that in all seasons the delay in the development of the EPB occurrence probability maxima with respect to the maxima of the west wind velocity is 1–3 h. It is in good agreement with the estimation of the time of the seeding perturbation development and the EPB rise to the topside ionosphere altitudes. The results can be considered a new confirmation of the theoretical conclusion (Kudeki model) about the key influence of the zonal west thermosphere winds on the equatorial plasma bubble generation.
Replacement of Acetonitrile with Ethanol in the Determination of Anthocyanins by Reversed-Phase High-Performance Liquid Chromatography
Authors: Deineka V. I. , Oleinits E. Yu. , Blinova I. P. , Deineka L. A.
Published: April 2024

It was found experimentally that the replacement of acetonitrile with ethanol upon the acidification of the mobile phase with phosphoric acid is an effective version for replacing acetonitrile. At that, the order of elution of glycosides of the same type of the five main anthocyanidins (delphinidin, cyanidin, petunidin, peonidin, and malvidin) does not change in eluents convenient for analysis, and the range of retention times for a complete set of such anthocyanins becomes noticeably narrower in going from acetonitrile to ethanol. To determine the effect of aglycone structure on the retention of derivatives of the same anthocyanidin (cyanidin), a mixture of six glycosides was used: one monoglycoside (3-glucoside), two 3-diglycosides (sophoroside and sambubioside), and two 3-triglycosides (2"-glucosylrutinoside and 2"-xylosylrutinoside). This mixture is a real set of anthocyanins, requiring the careful selection of the mobile phase for separating all components. In this work, based on an analysis of separation maps, the composition of a mobile phase based on ethanol is determined that ensures the achievement of the effective separation of these anthocyanins.
Comparison of Gas-Chromatographic Retention Parameters of Aliphatic Enyne Alcohols with the Data for Their Structural Analogues
Authors: Savina I. A. , Gusev D. M. , Zimina T. V. , Golovanov A. A. , Zenkevich I. G.
Published: April 2024

We studied the regularities of gas-chromatographic retention indices of aliphatic enyne alcohols containing С=С and С≡С bonds in the molecule (14 secondary and two tertiary homologues) on standard nonpolar polydimethylsiloxane stationary phases, which have not been characterized in sufficient detail earlier. Using homologous increments of retention indices iRI = RI – 100x, where х = int(M/14), М is the molecular weight number, and 14 is the mass number of the CH2 homological difference, one can compare data for structural analogs, including alkanols, alkenols, and alkynols. The features of comparing iRI values for compounds belonging to different homologous groups y ≡ M(mod14), for example, CnH2n+2O (y = 4), CnH2nO (y = 2), CnH2n–2O (y = 0), and CnH2n–4O (y = 12), are discussed. The main feature is that when the boundary value of y = 0 is passed, the relation between the parameter x and the number of carbon atoms in the molecule changes due to an increase in the formal unsaturation (the condition n = x – 1 is replaced by the condition n = x). Therefore, in the latter case, 100 should be subtracted from the iRI homologous increments to compare them with the data for structural analogs of other series. Taking this correction into account, we found that the iRI values for secondary enyne alcohols (12 ± 16) and previously characterized sec-alkynols (23 ± 21) virtually coincide, and for tertiary enyne alcohols, they are consistent with the data for all considered groups of structural analogues (alkanols, alkenols, and alkynols).
Automation of Sample Preparation Using Principles of Chromatomembrane Separation Methods in the Analysis of Aqueous and Air Media
Authors: Moskvin L. N. , Moskvin A. L. , Rodinkov O. V. , Yakimova N. M.
Published: April 2024

A summary of the accumulated experience of using chromatomembrane methods (CMMs) for automation of the chemical analysis of water and air media is presented. Particular emphasis is placed on flow-through methods of continuous analysis, where chromatomembrane methods often have no alternative.
Methodological Aspects of the Group Analysis of Organic Substances
Authors: Vershinin V. I.
Published: April 2024

Samples of complex composition usually contain similar organic compounds, molecules of which differ in the composition and structure but are characterized by common features (structural, functional, chemical analytical, etc.), uncharacteristic for other compounds. summary concentration of similar compounds are figures of the group composition of a studied sample. Procedures for their determination are widely used in analytical control and research laboratories. A special type of chemical analysis, group analysis (GA) was developed by the end of the 20th century. Structural group analysis (SGA) is considered an important special case of GA. Unfortunately, the methodological and metrological aspects of GA and SGA have been studied insufficiently. A conventional system of terms in this field also has not been developed. This paper considers the system of terms and the history GA, principles of group formation, and methods of the assessment of summary concentration. The unresolved problems of GA are emphasized. These are the uncertainty of the qualitative composition of groups, hindering the interpretation of the results of group analysis, and also intragroup selectivity and nonadditivity of the analytical signals. Possible solutions of these problems are considered.
Determination of Methane Dissolved in Water Using Metal-Oxide Sensors
Authors: Yablokov M. Yu. , Vasiliev A. A. , Gainutdinov R. V. , Sokolov A. V.
Published: April 2024

The method for the determination of dissolved methane in water using the system based on a tubular selective membrane permeable to volatile organic substances and impermeable to liquid water is proposed. Purified air is passed through the membrane tube immersed in water. The air inside the tube is saturated with methane dissolved in water, which diffuses through the tube wall. Methane concentration is measured in the air passing through the membrane tube using a semiconductor metal oxide sensor. The sensitivity threshold and the response time of the system are estimated.
Sequential Injection Amperometric Determination of Glucose in Saliva Using a Screen-Printed Electrode Modified with a Gold–Cobalt Binary System
Authors: Shaidarova L. G. , Chelnokova I. A. , Gafiatova I. A. , Gedmina A. V. , Budnikov G. K.
Published: April 2024

The catalytic activity of particles of gold, cobalt, and a gold–cobalt binary system electrodeposited on the surface of planar carbon electrodes was found in the oxidation of glucose in a neutral medium. The amperometric response of a screen-printed electrode modified with a gold–cobalt binary system was used as an analytical signal in the determination of glucose in a sequential injection system. The linear logarithmic dependence of current on the glucose concentration was observed in the range from 5 × 10–8 to 5 × 10–2 M. The use of a screen-printed electrode modified with a gold–cobalt binary system as an amperometric detector in a sequential injection system makes it possible to selectively determine glucose in saliva in the concentration range used for medical diagnosis.
Using Smartphones in Chemical Analysis
Authors: Shogah Z. A. C. , Bolshakov D. S. , Amelin V. G.
Published: April 2024

The review covers the current status and prospects for the development of digital colorimetry using a smartphone as a color recording device. The applications of the rapid analysis methodology for the control of environmental samples, biological fluids, food products, drugs, and some specific samples are systematized. Various approaches are considered, ensuring the formation of an analytical signal in digital colorimetry. The capabilities (advantages and disadvantages) of a smartphone equipped with various software products make it a universal, mobile, rapid, and sensitive tool in the analysis of various samples.
Determination of Lignin, Cellulose, and Hemicellulose in Plant Materials by FTIR Spectroscopy
Authors: Kostryukov S. G. , Matyakubov Kh. B. , Masterova Yu. Yu. , Kozlov A. Sh. , Pryanichnikova M. K. , Pynenkov A. A. , Khluchina N. A.
Published: April 2024

A procedure for determining concentrations of lignin, cellulose, and hemicellulose in plant materials using Fourier-transform IR spectroscopy in the middle spectral region was developed and tested. The procedure is based on the use of calibration functions reflecting the dependence of the intensity of analytical absorption bands on the concentration of lignin (1512 cm–1) and cellulose (1450 cm–1) in model samples; for hemicellulose, indirect correlations were used. The model samples were ternary mixtures consisting of lignin, bacterial cellulose, and hemicellulose in various proportions. The proposed method was tested on a wide range of plant biomass samples; it demonstrated adequate precision (RSD no more than 4%). The accuracy of the procedure for determining the main components of plant biomass (lignin, cellulose, and hemicellulose) was demonstrated using the standard addition method.
Methods for the Continuous Chromatographic Separation of Substances
Authors: Moskvin L. N. , Kostanyan A. E. , Moskvin A. L. , Rodinkov O. V. , Yakimova N. M.
Published: April 2024

Among many versions of methods for the chromatographic separation of substances, to date, insufficient attention has been paid to their continuous separation. Among a few exceptions is a review by Maryutina and Spivakov published in 2001 [4]. Our paper deals with a more detailed consideration of the attempts made for the continuous chromatographic separation of substances and the assessment of the efficiency of the solutions found. The aim of this review was to draw more attention to this promising direction for solving two interrelated problems. First, to creating systems for the continuous analytical control of complex multicomponent samples of the composition changing with time, and, second, to solving preparative and technological problems of the separation of substances with similar chemical properties. In the first case, the method ensures studies of the dynamics of changes in the composition of complex multicomponent mixtures in studying fast chemical processes, and, when used for technological purposes, it opens up a possibility of the continuous chemical-analytical monitoring of their course from the standpoint of economic efficiency and safety. In the second case, methods of continuous chromatographic separation ensure an increase in the efficiency and productivity of obtaining valuable high-purity substances.
Chromatographic Assessment of the Concentration of Phenolic Compounds in Wild Chamomile (Matricaria chamomilla L.) Extracts Obtained under Various Extraction Conditions
Authors: Temerdashev Z. A. , Chubukina T. K. , Vinitskaya E. A. , Kiseleva N. V.
Published: April 2024

Results of a study of water and water–alcohol extracts of wild chamomile (Matricaria chamomilla L.) depending on the conditions of their extraction by different methods are discussed. The test samples are wild chamomile samples collected in various regions of Russia. Phenolic components in their native forms were extracted from medicinal raw materials using infusion, maceration, microwave-assisted, ultrasound-assisted, and subcritical extraction, and by the pharmacopoeial method. Concentrations of individual components and total phenolic compounds in wild chamomile were determined by chromatographic methods. The HPLC determination of phenolic compounds with diode-array and mass spectrometric detection was carried out using gradient elution with a mixture of acetonitrile with 0.1% formic acid. Chlorogenic acid, ferulic acid glycosides, luteolin-7-O-glucoside, dicaffeoylquinic and chicoric acid, apigenin-7-glucoside, and apigenin were identified in water and water–alcohol extracts of wild chamomile. The dependence of the concentration of phenolic compounds on the geographical place of the growth of plant raw materials was studied based on value of this parameter in extracts of wild chamomile samples from different territories. The maximum total concentration of phenolic compounds (10.1 mg/g) was found in the extract of chamomile from FarmaTsvet (Krasnogorsk, Moscow oblast).
Modern Methods and Current Trends in the Analytical Chemistry of Flavanones
Authors: Yakupova E. N. , Ziyatdinova G. K.
Published: April 2024

The review covers the specific features of the structure of flavanones and a critical review of methods for their determination in various samples. The data are summarizes according to the methods of analysis: chromatographic, electrophoretic, spectral, and electrochemical. Analytical possibilities of each group of methods and their advantages and disadvantages are discussed. Special attention is paid to the use of chemically modified electrodes based on carbon nanomaterials, 3D nanoporous metal structures, composites of metal oxides and sulfide nanoparticles or dyes with carbon nanomaterials, and also combinations of modifiers of various types in flavanone voltammetry.
Mathematical Assessment of Combined Standard Uncertainty of Measurements in Using Concentration Ratio Calibration in Inductively Coupled Plasma Atomic Emission Spectrometry
Authors: Romanov S. N.
Published: April 2024

The mathematical assessment of effect of uncertainty components on measurement results in using concentration ratio calibration in inductively coupled plasma atomic emission spectrometry was performed. Formulas for the calculation of the relative standard uncertainty for different components were derived. It was shown that, in different scenarios of using concentration ratio calibration, the combined standard uncertainty basically depends on the repeatability of the determination of the intensity ratio of the analytical line of a test element to the line of the main matrix component of the sample
Prospects for the Development of Methods for the Analysis of High-Purity Volatile Substances
Authors: Sozin A. Yu. , Krylov V. A. , Chernova O. Yu. , Sorochkina T. G. , Bulanov A. D. , Kotkov A. P.
Published: April 2024

This review is devoted to the consideration of prospects and directions for the development of methods and approaches to the analysis of high-purity industrial gases and volatile hydrides, chlorides, fluorides, and organoelement compounds with natural and isotopically enriched compositions. The currently known capabilities for the determination of impurities in them using mass spectrometry, IR spectroscopy, gas chromatography, and chromatography–mass spectrometry are analyzed.
Preconcentration of Zinc, Cadmium, and Mercury(II) Ions on a Polymeric Modified Adsorbent Based on a Highly Basic ARA-8p Anionite and a Rhodanine Derivative
Authors: Uvaisova S. M. , Babuev M. A. , Damyrov U. M.
Published: April 2024

We studied the conditions for the adsorption of zinc, cadmium, and mercury(II) ions on a modified adsorbent based on an ARA-8p highly basic anion exchange resin and a Rhodanine derivative, 5-(4-carboxyphenyl-azo)rhodanine (ARA-8p-p-KBAR), in a batch mode. The values of pH, phase contact time, and adsorbate concentration at which the maximum recovery of zinc, cadmium, and mercury(II) ions was achieved were determined. The adsorption capacity of the adsorbent for the adsorbed ions was determined from the obtained adsorption isotherms. The calculated value of the free energy shows that adsorption proceeds with the formation of an ionic bond. Eluents were selected to ensure the quantitative desorption of zinc, cadmium, and mercury(II) ions. The interfering effect of macrocomponents and trace elements of water was studied; zinc, cadmium, and mercury(II) ions were quantitatively adsorbed by this adsorbent from a solution of a complex composition. A procedure was developed for the adsorption–atomic-absorption determination of zinc, cadmium, and mercury(II) ions in various water samples.