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Preflare Fluctuations of Radio Emission from Active Regions of the Sun According to Observations at RSTN
Geomagnetism and Aeronomy. 2024. Vol. 64. No. 7. P. 1054–1058.
Abramov-Maximov V. E., Bakunina I. A.
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 at lower frequencies (200–600 MHz)
begin later than those at high frequencies by 2–6 min. QPFs at frequencies of 2695–8800 MHz occur almost
synchronously. The highest amplitude of QPFs is observed at a frequency of 4995 MHz. The observed QPFs
can be explained by the force-free magnetic rope model (Solov’ev and Kirichek, 2023).
Спонтанное образование скин-слоя в воде с деформацией ОН-полосы КР вкладом компоненты льда 3200 см-1
Першин С. М., Степанов Е. В., Артемова Д. Г. et al., Письма в Журнал экспериментальной и теоретической физики 2026 Т. 123 № 6 С. 383–390
Открыто спонтанное образование в течение 4 ч скин-слоя дистиллированной воды толщиной до 3 мм при комнатной температуре с новыми свойствами. Обнаружены деформация ОН-полосы комбинационного рассеяния вкладом компоненты льда ( 3200 см-1), снижение коэффициента упругого рассеяния и его флуктуаций, а также увеличение на 20 капиллярах. Восстановление слоя после обогащения воздухом в результате перемешивания указывает на стабильность ...
Added: June 8, 2026
Zirnik G., Ostovari Moghaddam A., Zhukov S. et al., Journal of Materials Science: Materials in Electronics 2026 Vol. 37 Article 738
In regards to the advances in InGaZnO for flexible transistors applications, herein for the first time we measure the broadband radio-frequency range (10 Hz to 1 MHz) dielectric permittivity ε′ and electrical conductivity σ of InGaZnO4 nanoparticle layers at different temperatures ranging from 10 to 300 K. The InGaZnO4 nanoparticles prepared by metal–nitrate–glycol gel decomposition method exhibited ...
Added: June 6, 2026
Flamarion M. V., Pelinovsky E., Nonlinear Dynamics 2026 Vol. 114 Article 784
In this article, we investigate wave packet and solitary wave dynamics in the Whitham–Ostrovsky (WO) equation. By means of a multiple-scales expansion, we formally derive a nonlinear Schrödinger (NLS) equation governing the envelope evolution.The corresponding modulational stability diagram is then obtained using the Lighthill criterion. We show that sufficiently large values of the low-frequency dispersive term render ...
Added: June 5, 2026
Hazarika A. P., Das A., Das S. K. et al., Physica B: Condensed Matter 2026 Vol. 738 Article 418803
Lemon grass (Cymbopogon citratus, LG-SiO2), horsetail (Equisetum debile, SG-SiO2), and cassava leaves (Manihot esculenta, CL-SiO2) were used to green-synthesize silica (SiO2) nanoparticles (NPs). While LG-SiO2 and SG-SiO2 had strong (101) peaks and a large 22° amorphous peak, XRD of CL-SiO2 verified crystallinity. LG-SiO2 (agglomerated porous), SG-SiO2 (rectangular-cube agglomerates), and CL-SiO2 (flake agglomerates) had different morphologies. The TEM image of LG-SiO2 revealed agglomerated ...
Added: June 4, 2026
Kornbleuth M., Opher M., Drake J. F. et al., Astrophysical Journal 2026 Vol. 1004 No. 1 Article 1
The shape of the heliosphere, regarded as comet-like since the 1960s, has recently been the subject of intense debate in the last decade. There is disagreement as to whether the heliospheric tail extends to ∼10,000 au in a comet-like shape or if it is short (∼400 au) with a split. Energetic neutral atom (ENA) maps from ...
Added: June 3, 2026
Nishant T., Kartsev A., Saswata G. et al., Journal of Materials Chemistry C 2026 Article -
Overheating remains a critical limitation in high-performance electronic and computing systems,
necessitating the development of efficient thermal management fluids. In this work, a magnetically
responsive hybrid ferrofluid was developed by incorporating two-dimensional hexagonal boron nitride
(2D-hBN) nanosheets into a Mn–Zn–ferrite-based ferrofluid. The hybrid system retains magnetic
responsiveness while leveraging the high in-plane thermal conductivity and chemical stability of 2D-hBN
nanosheets. ...
Added: June 2, 2026
Fortuna A. S., A.I. Kartsev, Gorshenkov M. V. et al., Journal of Alloys and Compounds 2026 Vol. 1070 Article 188711
The τ-phase in Mn-Al-Ga alloys is a promising candidate for rare-earth-free permanent magnets. This study re-veals that the τ(γ₂)-phase in rapidly quenched Mn55Al36Ga9 ribbons contains a high density of dislocations, which
form antiphase boundaries (APBs). Using transmission electron microscopy and density functional theory, we
demonstrate that Mn atoms at these APBs couple antiferromagnetically. This antiferromagnetic interaction is
identified ...
Added: June 2, 2026
Dikhtievskaya K., Argunov E., Alexey I. Kartsev et al., The Journal of Physical Chemistry Letters 2026 Vol. 17 No. 17 P. 4999–5004
In this study we revealed the effect of scandium doping on the electronic and superconducting properties of the MgB2 compound. Calculations demonstrate that Sc substitutes for Mg atoms, acting as an electron donor. Mg substitution diminishes the density of states in the σ-band and attenuates the electron–phonon coupling, thereby elucidating the reduction in critical temperature. Simultaneously, ...
Added: June 2, 2026
Duran E. ., Pulgar A., Izquierdo R. et al., Physica Status Solidi (A) Applications and Materials 2026 Vol. 223 No. 7 Article e202500942
Ceramic superconductors exhibit remarkable properties, including zero electrical resistance and potent magnetic behavior, operating at temperatures as high as the boiling points of liquid nitrogen (77 K) and liquid hydrogen (20 K). These characteristics position them as key enablers for sustainable technologies spanning electric propulsion, lossless energy transmission, advanced medical imaging, and quantum computation. This review presents ...
Added: June 1, 2026
Borisov V., Danilov V., Электросвязь 2025 № 12 С. 73–84
Представлены результаты математического моделирования процесса полевой эмиссии из катода малых размеров – одного из основных физических процессов, обеспечивающих работы многих электронных устройств, в частности FED-дисплеев (устройства, работающие на принципе полевой эмиссии), кантилеверов и т.д. Дается краткий обзор текущих результатов в области исследования, обосновывается актуальность задачи, приводятся примеры наиболее вероятного использования результатов решения задачи. Обсуждаются физические ...
Added: May 29, 2026
Jiang Q., Fang J., Chen J. et al., Science China Information Sciences 2026 Vol. 69 No. 6 Article 162402
Resonators based on nanoelectromechanical systems (NEMS) using two-dimensional (2D) materials with high-quality factors and excellent electrical control are critical for tunable coherent phonon dynamics, resonant sensors and wireless communications. However, their performance is fundamentally limited by the lack of a unified framework governing energy dissipation mechanisms and their electrical tunability. Here, we synergistically modulate both ...
Added: May 28, 2026
Elesin L., Shilov A., Jana S. et al., Advanced Functional Materials 2026 P. 1–10
Thermoelectric materials, long explored for energy harvesting and thermal sensing, convert heat directly into electrical signals. Extending their application to the terahertz (THz) frequency range opens opportunities for low-noise, bias-free THz detection, yet conventional thermoelectrics lack the sensitivity required for practical devices. Thermoelectric coefficients can be strongly enhanced near van Hove singularities (VHS), though these ...
Added: May 28, 2026
Degtyarev A., Bakhurin S., Yudin N., DSPA 2026 P. 1–6
This paper investigates one possible solution to the problem of self-interference cancellation (SIC) arising in the design of in-band full-duplex (IBFD) communication systems. Self-interference cancellation is performed in the digital domain using multilayer nonlinear models adapted via gradient-based optimization. The presence of local minima and saddle points during the adaptation of multilayer models limits the ...
Added: May 26, 2026
Qian X., Deng Y., Lev N. Shchur et al., Physica A: Statistical Mechanics and its Applications 2026 Vol. 696 Article 131679
We perform a Monte Carlo analysis of the Ising model on many three-dimensional lattices. By means of finite-size scaling we obtain the critical points and determine the scaling dimensions. As expected, the critical exponents agree with the three-dimensional Ising universality class for all models. The irrelevant field, as revealed by the correction-to-scaling amplitudes, appears to ...
Added: May 24, 2026
Melentiev P. N., Калмыков А. С., Гритченко А. С. et al., Успехи физических наук 2024 Т. 194 № 11 С. 1130–1145
Представлен краткий обзор достигнутого уровня оптических методов детектирования единичных молекул в биомедицинских приложениях. Показано, что регистрация флуоресценции единичных молекул красителей, ковалентно связанных с антителами (биомолекулами), совместно с использованием современных методов нанофотоники может быть применена для решения различных задач в биологии и медицине: визуализации биомолекул, токсинов, вирусных частиц, определения ультранизких концентраций аналитов напрямую во взятой пробе, ...
Added: May 21, 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
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
P.A.Bespalov, O.N.Savina, Geomagnetism and Aeronomy 2023 Vol. 63 No. 7 P. 910–915
According to modern concepts, Type I noise storms in the meter wavelength range (30–400 MHz), consisting of a large number of narrow-band short bursts, are excited in the rarefied solar corona. These radiations are characterized by a high brightness temperature and circular polarization. Despite many advances in theory and confidence that the mechanism of radiation ...
Added: December 22, 2023
Bakunina I. A., Мельников В. Ф., Шаин А. В. et al., В кн.: Труды XXVII Всероссийской ежегодной конференции по физике Солнца “Солнечная и солнечно-земная физика - 2023”, 9-13 октября 2023 года, Санкт-Петербург, ГАО РАН.: СПб.: ГАО РАН, 2023. С. 23–26.
It is shown that the positions of the flux ropes in the general spatial structure of the active region magnetic field reconstructed in the NLFFF approximation for flares with and without CME are different: magnetic flux ropes are located quasi-parallel to the overlying magnetic field lines in the events with CME, and quasi-perpendicular in the ...
Added: December 3, 2023
I. A. Bakunina, Melnikov V. F., Shain A. V. et al., Geomagnetism and Aeronomy 2022 Vol. 62 No. 8 P. 1066–1072
The dynamics of the preflare phase of microwave and ultraviolet emission for M-class X-ray flares in three active regions (ARs), two flares with coronal mass ejections (CMEs) and one flare without a CME, were considered. Extrapolation of the magnetic field in the AR corona showed that eruptive events were associated with the formation of a ...
Added: February 16, 2023
Abramov-Maximov V. E., I. A. Bakunina, Geomagnetism and Aeronomy 2022 Vol. 62 No. 7 P. 895–902
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 ...
Added: February 16, 2023