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Signs of Preparation of Solar Flares in the Microwave Range
Geomagnetism and Aeronomy. 2022. Vol. 62. No. 7. P. 895–902.
Abramov-Maximov V. E., I. A. Bakunina
We present a study of the spatial distribution of quasi-periodic oscillations (QPOs) of microwave emission in three solar active regions before flares. The following events are considered: SOL2011-09-06T01:50M5.3, SOL2011-09-25T02:33M4.4, and SOL2012-07-08T04:19C6.6. Daily observations on the Nobeyama Radioheliograph at a frequency of 17 GHz are used. In all three cases, pre-flare trains of the QPOs of microwave emission are detected. The length of the trains is 3–4 pulses. In all cases, the most strongly detected oscillations manifested themselves in a compact zone in an active region coinciding with the region of maximum microwave emission brightness during the flare.
The Journal of Physical Chemistry Letters 2026 Vol. 17 No. 18 P. 5386–5394
We demonstrate and rationalize the effect of Au nanoparticles (NPs) on the hierarchical g-C3N4/CeO2 heterojunction. g-C3N4/CeO2 decorated with monodispersed plasmonic Au NPs was synthesized. Detailed analyses showed that CeO2 nanocubes and monodispersed Au NPs were evenly distributed over the 2D g-C3N4 surface, forming a robust interface enriched with abundant active sites. The structure enabled efficient separation of photogenerated charge ...
Added: May 16, 2026
Das A., Paul R., Sharma N. et al., Colloids and Surfaces A: Physicochemical and Engineering Aspects 2026 Vol. 728 P. 138830
Niobium-doped TiO2 (Nb-TiO2), demonstrates dual functionality as an efficient photocatalyst for dye degradation and a promising photoelectrocatalyst for water oxidation. Nb incorporation via a facile hydrothermal method was confirmed by XRD (Rietveld refinement), XPS, TEM, FT-IR, Raman, and BET analyses, indicating successful lattice doping and structural modification. Photocatalytic dye degradation experiments were conducted using a model ...
Added: May 16, 2026
Kolokolov I., Lebedev V., Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 2026 Vol. 113 Article 054117
We theoretically investigate the correlation functions of the phase of a light wave propagating through a
turbulent medium. We use an equation for the logarithm of a wave packet envelope, which includes a secondorder
nonlinear term. Based on this equation, we develop a diagrammatic technique to calculate corrections
to the correlation function obtained in the linear approximation. We ...
Added: May 15, 2026
Гущина В. А., / Series chemrxiv-2023-vpzhz-v2 "ChemRxiv". 2023.
All-inorganic perovskite CsPbBr3 and Cs4PbBr6 nanoparticles are being intensively studied due to their unique properties and wide range of applications; however, however, the nature of their optical properties is not yet fully understood due to the difficulty of synthesis of singlephase nanoparticles. In this article we describe the features of the synthesis of single-phase particles ...
Added: May 14, 2026
Гущина В. А., Mendeleev Communications 2025 Vol. 35 No. 2 P. 193–195
All-inorganic perovskite CsPbBr3 and Cs4PbBr6 nanoparticles are intensively studied for their unique optical properties, though synthesizing single-phase nanoparticles has posed challenges. Detailed synthesis method of CsPbBr3 and Cs4PbBr6 single-phase nanoparticles and their chemical and phase analysis are described. Distinctive optical characteristics, such as photoluminescence, optical band gap and the Urbach tail region, are revealed and explained within the current ...
Added: May 14, 2026
Гущина В. А., Physics of Complex Systems, Russia 2026 Vol. 7 No. 1 P. 3–15
Heterostructures based on ZnO nanorods and CsPbBr3 nanocrystals were investigated for their potential as semiconductor SERS substrates. We found that ZnO morphology governs the efficiency of interfacial energy transfer, leading to enhanced photoluminescence under 390 nm excitation and a noticeable reduction of the bandgap in the composites. Raman analysis revealed a pronounced intensity enhancement and ...
Added: May 14, 2026
Bisnovatyi-Kogan G., Kondratyev I., Moiseenko S. G., International Journal of Modern Physics A 2025 Vol. 40 No. 7 Article 2550018
Bright transient objects in different wave bands have been discovered in recent years.
To explain these short (from ms to s), and very powerful events, different models, galactic and
extragalactic, have been considered. One of the popular models is based on the suggestion of
transformation of the magnetized plasma blob, presumably a magnetohydrodynamic (MHD)
shock wave, moving with relativistic ...
Added: May 11, 2026
Торопина О. Д., Бисноватый-Коган Г. С., Moiseenko S. G., Astronomy Reports 2025 Vol. 69 No. Suppl. 1 P. 80–90
The results of MHD simulations of supersonic astrophysical and laboratory jets in an external
poloidal magnetic field (Br,Bz) taking into account the rotation of the matter, are presented. The ejected
matter is collimated by the magnetic field, the degree of collimation and the flow structure depend on the
relation between of the magnetic field induction and the angular ...
Added: May 11, 2026
Morozov E. V., Demin A. S., Borovitskaya I. V. et al., Inorganic Materials: Applied Research 2026 Vol. 17 No. 3 P. 619–626
This article presents the results of experiments on the impact of powerful pulsed ion-plasma and
electron flows generated in the working chamber of the Plasma Focus PF-5M installation during each highvoltage
discharge on a model aluminum alloy B95. It is shown that the general characteristics of the alloy’s
damage upon exposure to pulsed flows of helium ions (HI) ...
Added: May 4, 2026
A. A. Ponomarev, N. L. Aleksandrov, Plasma Physics Reports 2026 Vol. 52 No. 3 P. 367–378
An approximate method for calculating drift velocity and other kinetic coefficients of heavy ions
in a light gas is generalized to gaseous mixtures. Obtained equations are used to calculate the mobilities of
and ions, as well as rate constants for inelastic ion–molecule processes with these ions in helium with
small additions of O2 under an electric field. Calculated ...
Added: April 27, 2026
Domrin V. I., Malova H. V., V. Yu. Popov et al., Cosmic Research 2026 Vol. 64 No. 2 P. 238–252
During magnetospheric perturbations a relatively thin current sheet with thickness about several
proton gyroradii forms in the Earth’s magnetotail. In a framework of the kinetic model describing current
sheet thinning in the magnetotail, the processes of its formation are investigated depending on the normal
magnetic field magnitude which affects both the current sheet structure and particle dynamics within ...
Added: April 27, 2026
Tsareva O. O., Malova H. V., V. Yu. Popov et al., Plasma Physics Reports 2026 Vol. 52 No. 2 P. 179–185
The influence of asymmetry of plasma sources on the structure and spatial localization of a superthin
current sheet (STCS) supported by demagnetized electrons is studied using a self-consistent model. The
simulation takes into account the presence of a single plasma source in the northern hemisphere, which
makes the plasma flow asymmetric. It is demonstrated that the asymmetry of ...
Added: April 27, 2026
П.А.Беспалов, О.Н. Савина, Геомагнетизм и аэрономия 2025 Т. 65 № 5 С. 620–628
Several basic models of frequency dynamics in quasi-periodic VLF emissions with spectral form repetition
periods from 10 to 300 s are considered. In all cases, we are talking about manifestations of cyclotron instability
of electron radiation belts thet are well described within the framework of the plasma magnetospheric maser
theory based an the averaged self-consistent system of quasi-linear ...
Added: April 25, 2026
Bondarenko G.G., Fisher M. R., Kristya V. I., Bulletin of the Russian Academy of Sciences: Physics 2026 Vol. 90 No. 4 P. 572–576
A model of the cathode layer of a glow gas discharge with a thin dielectric film on a fraction of the
cathode’s working surface is formulated. It is shown that a glow discharge most rapidly transits to an arc discharge,
accompanied by a significant increase in discharge current density and a decrease in cathode voltage
drop, if the ...
Added: April 25, 2026
Lu X., Tognazzi A., Klimov V. et al., Plasmonics 2026 Vol. 21 P. 1503–1512
Plasmonic nanostructures typically exhibit shifts in their resonant wavelength in response to changes in the refractive index of the surrounding medium. This limits their applications in scenarios requiring stable optical resonances. Here we present a metallic-dielectric hybrid metasurface that exhibits stable multi-wavelength resonance even if the refractive index of its surrounding varies. To quantitatively evaluate the stability of ...
Added: April 22, 2026
I. A. Bakunina, Melnikov V. F., Shain A. V. et al., Geomagnetism and Aeronomy 2024 Vol. 64 No. 8 P. 1237–1249
Using statistics from 15 X-ray class M flare events, the features of the position and orientation of magnetic flux ropes in the general spatial structure of the magnetic field of the active region (AR) during flares and coronal mass ejections (CME) were studied by reconstructing the coronal magnetic field from the photosphere to the corona ...
Added: February 17, 2025
Abramov-Maximov V. E., Bakunina I. A., Geomagnetism and Aeronomy 2024 Vol. 64 No. 7 P. 1054–1058
For the first time, several flare events are analyzed based on multifrequency observations using the
Radio Solar Telescope Network. The purpose of the analysis is to identify signs of flare preparation. In all
considered cases, preflare quasi-periodic fluctuations (QPFs) of radio emission were detected. The duration of
preflare wavetrains is 6–20 min. Wavetrains consist of 3–5 pulses. QPFs ...
Added: February 17, 2025
Bakunina I. A., Мельников В. Ф., Шаин А. В. et al., В кн.: XXVIII всероссийская ежегодная конференция «Солнечная и солнечно-земная физика-2024», Труды.: СПб.: Главная (Пулковская) астрономическая обсерватория РАН, 2024. С. 25–28.
It is shown on a sample of 15 M-class X-ray flares that CMEs occur in events with «open» magnetic ropes reconstructed in the NLFFF approximation. Magnetic ropes coincide with radio brightness maxima at 17 GHz. Several hours before the flare, in the region of magnetic ropes, a glow of loops in the EUV (94, 131 ...
Added: December 1, 2024
СПб.: Главная (Пулковская) астрономическая обсерватория РАН, 2024.
Сборник содержит доклады, представленные на XXVIII Всероссийскую ежегодную конференцию по физике Солнца «Солнечная и солнечно-земная физика – 2024» (7 – 11 октября 2024, ГАО РАН, Санкт-Петербург). Конференция проводилась Главной (Пулковской) астрономической обсерваторией РАН при поддержке секции «Солнце» Научного совета по астрономии РАН и секции «Физика солнечной плазмы» Научного совета «Солнце-Земля». Тематика конференции включала в себя ...
Added: December 1, 2024
I. A. Bakunina, Melnikov V. F., Kuznetsov S. A. et al., Geomagnetism and Aeronomy, Netherlands 2023 Vol. 63 No. 8 P. 1154–1166
The dynamics of the magnetic field reconstructed in the nonlinear force-free approximation in the pre-flare and post-flare phases of M-class X-ray flares in seven active regions is considered: two flares with a coronal mass ejection (CME), two flares with eruption but no CMEs, and three flares without eruption. Extrapolation of the magnetic field to the ...
Added: February 3, 2024
Abramov-Maximov V. E., I. A. Bakunina, Geomagnetism and Aeronomy, Springer, Switzerland 2023 Vol. 63 No. 7 P. 916–919
We present a study of the frequency of occurrence of quasi-periodic fluctuations (QPFs) of microwave
radiation from solar active regions at the pre-flare stage. We used correlation curves obtained with the
Nobeyama Radioheliograph (NoRH). We analyzed 529 flares of classes X, M, and C (according to the GOES
classification). In a significant number of considered events (approximately 75% ...
Added: December 28, 2023