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Abstract By using the magnetic field data from Van Allen Probes, we analyzed the distribution characteristics of the electromagnetic environment in the inner magnetosphere on different Dst* index and magnetic local time. Our results show that for the response of different current systems, the dawn‐dusk and noon‐midnight asymmetry distribution of the residual magnetic field δB increases with Dst* index. When Dst*

In this work, the influence of the Fe and Fe/C co-doped buffer on the AlGaN/GaN HEMTs is systematically investigated and compared. Due to the pronounced Fe tail in the unintentionally doped layer of the Fe-doped buffer compared to the Fe/C co-doped buffer, and the utilization of a two-step C doping process in the Fe/C co-doped buffer, it results in effectively reducing leakage current and increasing breakdown voltage without sacrificing saturation current and peak transconductance. Meanwhile, the RF characteristics of the Fe/C co-doped buffer are also superior to the Fe-doped buffer. More importantly, Drain Transient Current measurements indicate that the current collapse in the Fe/C co-doped buffer is smaller than that in the Fe-doped buffer. Through simulation analysis, the reason was identified: In the near-channel region, the weaker Fe tail effect in Fe/C co-doped buffer leads to a lower acceptor trap ionization. When the concentration of C exceeds 1 × 1016 cm−3, the ionization of traps introduced by Fe is suppressed. Additionally, the two-step C impurity distribution in the Fe/C co-doped buffer design modulates the electric field and potential, reducing the effective range of the electric field and potential, thereby effectively reducing the trap effects. These results are highly meaningful for the design of high-power amplifier epitaxial structures. [ABSTRACT FROM AUTHOR]

Chiral superconductors, a unique class of unconventional superconductors in which the complex superconducting order parameter winds clockwise or anticlockwise in the momentum space1, represent a topologically non-trivial system with intrinsic time-reversal symmetry breaking (TRSB) and direct implications for topological quantum computing2,3. Intrinsic chiral superconductors are extremely rare, with only a few arguable examples, including UTe2, UPt3 and Sr2RuO4 (refs. 4–7). It has been suggested that chiral superconductivity may exist in non-centrosymmetric superconductors8,9, although such non-centrosymmetry is uncommon in typical solid-state superconductors. Alternatively, chiral molecules with neither mirror nor inversion symmetry have been widely investigated. We suggest that an incorporation of chiral molecules into conventional superconductor lattices could introduce non-centrosymmetry and help realize chiral superconductivity10. Here we explore unconventional superconductivity in chiral molecule intercalated TaS2 hybrid superlattices. Our studies reveal an exceptionally large in-plane upper critical field Bc2,|| well beyond the Pauli paramagnetic limit, a robust π-phase shift in Little–Parks measurements and a field-free superconducting diode effect (SDE). These experimental signatures of unconventional superconductivity suggest that the intriguing interplay between crystalline atomic layers and the self-assembled chiral molecular layers may lead to exotic topological materials. Our study highlights that the hybrid superlattices could lay a versatile path to artificial quantum materials by combining a vast library of layered crystals of rich physical properties with the nearly infinite variations of molecules of designable structural motifs and functional groups11.By incorporating chiral molecules into conventional superconductor lattices such as TaS2 to form a hybrid superlattice, non-centrosymmetry could be introduced and can be shown to help lead to unconventional superconductivity. [ABSTRACT FROM AUTHOR]

Ultra‐low frequency (ULF) waves contribute significantly to the dynamic evolution of Earth's magnetosphere by accelerating and transporting charged particles within a wide energy range. A substantial excitation mechanism of these waves is their drift‐bounce resonant interactions with magnetospheric particles. Here, we extend the conventional drift‐bounce resonance theory to formulate the nonlinear particle trapping in the ULF wave‐carried potential well, which can be approximately described by a pendulum equation. We also predict the observable signatures of the nonlinear drift‐bounce resonance, and compare them with spacecraft observations. We further discuss potential drivers of the pendulum including the convection electric field and the magnetospheric dayside compression, which lead to additional particle acceleration or deceleration depending on magnetic longitude. These drivers indicate preferred regions for nonlinear ULF wave growth, which are consistent with previous statistical studies. Plain Language Summary: In Earth's magnetosphere, electromagnetic oscillations in the mHz frequency range referred to as ultra‐low frequency (ULF) waves have been frequently reported in space and ground‐based observations. These waves have been known to interact resonantly with magnetospheric particles during their drift and bounce motions, which plays a key role in the acceleration and transport of charged particles in the Van Allen radiation belts. Drift‐bounce resonance occurs when a resonant particle experiences repetitive patterns of the wave field over consecutive bounce cycles along its drift orbit, thus enabling a cumulative energy exchange between waves and particles. In previous studies of drift‐bounce resonance, a linearization approach is applied for simplicity. Here, we extend the conventional theory into the nonlinear regime, to formulate the nonlinear trapping of particles based on a pendulum equation and to predict the characteristic signatures of drift‐bounce resonance. Moreover, we discuss the potential drivers of the pendulum, including the magnetospheric convection and the dayside compression, which break the symmetry in the phase portrait of the particle trajectories and therefore, lead to continuous particle acceleration or deceleration depending on magnetic longitude. Our study on nonlinear drift‐bounce resonance is helpful to the understanding of the ULF wave‐particle interactions and the wave excitation processes. Key Points: A nonlinear framework for drift‐bounce resonance is developed to describe the particle behavior in Ultra‐low frequency (ULF) wavesNonlinear drift‐bounce resonance is characterized observationally by rolled‐up structures in particle pitch angle spectrumOur theory predicts that dayside and dusk sectors are preferred regions for nonlinear ULF wave growth [ABSTRACT FROM AUTHOR]

Force-free current sheets, characterized by field-aligned electric currents and approximately uniform plasma pressures, have been widely observed in the planetary magnetosphere and throughout the heliosphere. Recent observations of force-free current sheets have clearly shown the presence of anisotropic electron distributions with different temperatures perpendicular and parallel to the local magnetic field. In most of the kinetic models for one-dimensional, force-free current sheets, however, the electron distributions are nearly isotropic, which necessitates the construction of new models accounting for the electron temperature anisotropy. In this paper, we develop a model for anisotropic force-free current sheets, by incorporating the magnetic moment as an additional invariant of motion into the nearly isotropic electron distribution function of a previous model. Despite the different electron distributions, the electromagnetic profiles of the new model are often close to those in the nearly isotropic model. The applicability of our model is then validated via a comparison to a typical force-free current sheet in the Jovian magnetodisk, which shows good agreement between the model and the observations. [ABSTRACT FROM AUTHOR]

This experiment was conducted to study the effects of dietary supplementation with acidifiers on the growth performance, meat quality, and intestinal health of broiler chickens. A total of 648 male Arbor Acres broiler chickens at 1 d old were randomly divided into 6 groups, and each group consisted of 6 replicates with 18 broilers per replicate. The dietary treatments were as follows: negative control (NC, the basal diet), NC + antibiotic (enramycin, 8 mg/kg, positive control [PC]), NC + phosphoric acid (PA, 0.1, 0.2, and 0.3 g/kg), and NC + lactic acid (LA, 0.3 g/kg). The feeding trial lasted for 42 d. The results showed that the feed-to-gain ratio of the NC + acidifier groups was lower than that of the NC and PC groups from 1 to 42 d (P

Pulsating auroras are usually observed with ultralow-frequency (ULF) waves in the Pc 3–5 band (period 10–600 s). These auroras are thought to result from interactions between energetic electrons and chorus waves, but their relationship with ULF waves remains an open question. In this study, we investigated this question by conducting a comparative study on two ULF wave events with pulsating auroras observed near the magnetic footprints. Conjugate observations from the Magnetospheric Multiscale mission and the Chinese Yellow River Station were used. In both events, lower-band chorus waves were observed, which were suggested to be connected with the auroral pulsations by wavelet analysis. The intensity of these waves oscillates at the period of the ULF waves, but the physics laid behind them differs by events. During the event of 22 January 2019, compressional ULF waves changed the threshold for the whistler anisotropy instability periodically, affecting the emission of chorus waves. In the event on 10 January 2016, poloidal ULF waves modulated the chorus wave generation by regulating electron temperature anisotropy through drift resonance. ULF waves in these events may originate from perturbations in the solar wind. We highlight the role of ULF waves in the solar wind–magnetosphere–ionosphere coupling, which requires further study.

Objective To investigate the effect of silencing MFG-E8 gene on the sensitivity of SKOV3 cells to anticancer drugs and related mechanisms. Methods SKOV3 cells were transfected with MFG-E8 siRNA (Msi) and NC siRNA (Csi), respectively and the efficiency of transfection was confirmed by Western blot. The sensitivity of SKOV3 cells to cisplatin was observed by CCK-8 assay after transfection. The mRNA expression of ABCB1 and ABCC1 were detected by qRT-PCR. Effect of silencing MFG-E8 on the expression of ETM-related protein was detected by qRT-PCR and Western blot. Results MFG-E8 siRNA could effectively silence the expression of MFG-E8 protein. With the increasing drug concentration, the proliferation inhibition rate of each group also increased, and the cell proliferation inhibition rate of MFG-E8 siRNA group increased significantly (P < 0.01). Compared with NC siRNA group, downregulation of MFG-E8 expression led to decreased SKOV3 cell proliferation at 48h or 72h after 3 μg/ml cisplatin treat ment (P < 0.05). qRT-PCR results showed that the mRNA expression of ABCB1 and ABCC1 in Msi group were significantly lower than those in Csi group. qRT-PCR and Western blot results showed that silencing MFG-E8 gene down-regulated the mRNA and protein expression of N-Cadherin, Vimentin and Snail and up-regulated the expression of E-Cadherin. Conclusion Silencing the MFG-E8 gene can increase the sensitivity of SKOV3 cells against anti-tumor drugs and down-regulate the mRNA expression of ABCB1 and ABCC1, which may be related to the inhibition of EMT progression.

Energetic electron measurements and spacecraft charging are of great significance for theoretical research in space physics and space weather applications. In this paper, the energetic electron detection package (EEDP) deployed on three Chinese navigation satellites in medium Earth orbit (MEO) is reviewed. The instrument was developed by the space science payload team led by Peking University. The EEDP includes a pinhole medium-energy electron spectrometer (MES), a high-energy electron detector (HED) based on ΔE-E telescope technology, and a deep dielectric charging monitor (DDCM). The MES measures the energy spectra of 50−600 keV electrons from nine directions with a 180°×30° field of view (FOV). The HED measures the energy spectrum of 0.5−3.0 MeV electrons from one direction with a 30° cone-angle FOV. The ground test and calibration results indicate that these three sensors exhibit excellent performance. Preliminary observations show that the electron spectra measured by the MES and HED are in good agreement with the results from the magnetic electron-ion spectrometer (MagEIS) of the Van Allen Probes spacecraft, with an average relative deviation of 27.3% for the energy spectra. The charging currents and voltages measured by the DDCM during storms are consistent with the high-energy electron observations of the HED, demonstrating the effectiveness of the DDCM. The observations of the EEDP on board the three MEO satellites can provide important support for theoretical research on the radiation belts and the applications related to space weather.

Alfven-branch waves provide an efficient means for transporting energy into the auroral oval. Here, we report observations of these waves obtained by the Fengyun-3E (FY-3E)/ACMag instruments, which are designed to detect three-dimensional AC magnetic fields in the 0.05–25 Hz band. The observations suggest that broadband waves are a permanent feature of the auroral oval, although their amplitude and locations vary with the global state of the magnetosphere. We primarily focus on the data obtained from 10 July 2021 to 26 August 2021, during which a series of recurrent storms driven by solar wind corotating interaction regions (CIRs) occurred. Analysis of the observations shows that the auroral-oval waves grow in amplitude (1–3 orders of magnitude) and shift to lower latitude (∼10°) immediately following the decrease in the SYM-H index in each storm. Further investigation reveals the response of the auroral-oval waves has a time scale equal to or less than FY-3E’s effective revisiting time, which is about 45 min. The observations presented in this paper confirm that the FY-3E/ACMag instruments provide a high-resolution monitor of the auroral-oval waves and could further our understanding of auroral physics.

Structural analyses of transmission towers against tornados, which are of vital practical significance in design and maintenance of the structures in regions suffering from the convective weather, were rarely reported by the wind engineering community up to today. To balance the computing efficiency and the simulation accuracy, numerical calculations based on Wen's tornadic velocity model are employed to analyze the tornado‐induced structural responses of a 131‐meter‐high free‐standing transmission tower in east China in this article. Results suggest that both the tornadic load and the structural response are noticeably greater in the lateral direction than in the longitudinal direction, and they are found to be highly nonstationary due to the traveling nature of the tornado. In addition, according to the present study, the transmission tower is not prone to the strength failure during the tornadic event and slight fatigue damages are accumulated on the tower body due to the tornadic action which can be timely warned using the structural health monitoring strategy based on field measurements of low‐order structural natural frequencies. Besides the points mentioned above, the innovations of the present research additionally include the following: (1) tornado‐induced structural responses and atmospheric boundary layer wind‐induced structural behaviors have been compared to provide conclusions of theoretical significance; (2) a novel fatigue damage assessment method based on the high‐circle fatigue damage accumulation theory has been applied to the analysis of tornado‐induced structural damage; (3) the structural configuration of a key joint on a main chord has been optimized against the tornado based on the advanced response surface optimization method. [ABSTRACT FROM AUTHOR]

Kinetic-scale magnetic holes (KSMHs) are structures characterized by a significant magnetic depression with a length scale on the order of the proton gyroradius. These structures have been investigated in recent studies in near-Earth space, and found to be closely related to energy conversion and particle acceleration, wave-particle interactions, magnetic reconnection, and turbulence at the kinetic-scale. However, there are still several major issues of the KSMHs that need further study — including (a) the source of these structures (locally generated in near-Earth space, or carried by the solar wind), (b) the environmental conditions leading to their generation, and (c) their spatio-temporal characteristics. In this study, KSMHs in near-Earth space are investigated statistically using data from the Magnetospheric Multiscale mission. Approximately 200,000 events were observed from September 2015 to March 2020. Occurrence rates of such structures in the solar wind, magnetosheath, and magnetotail were obtained. We find that KSMHs occur in the magnetosheath at rates far above their occurrence in the solar wind. This indicates that most of the structures are generated locally in the magnetosheath, rather than advected with the solar wind. Moreover, KSMHs occur in the downstream region of the quasi-parallel shock at rates significantly higher than in the downstream region of the quasi-perpendicular shock, indicating a relationship with the turbulent plasma environment. Close to the magnetopause, we find that the depths of KSMHs decrease as their temporal-scale increases. We also find that the spatial-scales of the KSMHs near the subsolar magnetosheath are smaller than those in the flanks. Furthermore, their global distribution shows a significant dawn-dusk asymmetry (duskside dominating) in the magnetotail.

Magnetic cavities play important roles in the energy cascade, conversion and dissipation in turbulent plasmas. Here, the authors show a theoretical insight into magnetic cavities by deriving a self-consistent, kinetic theory of these coherent structures.

Theoretical studies suggested that plasmapause surface waves related to the sharp inhomogeneity exist and act as a source of geomagnetic pulsations. Here, the authors show direct observations of a plasmapause surface wave and its impacts during a geomagnetic storm using multi-satellite and ground-based observations.

Cold (few eV) ions of ionospheric origin are widely observed in the lobe region of Earth’s magnetotail and can enter the ion jet region after magnetic reconnection is triggered in the magnetotail. Here, we investigate a magnetotail crossing with cold ions in one tailward and two earthward ion jets observed by the Magnetospheric Multiscale (MMS) constellation of spacecraft. Cold ions co-existing with hot plasma-sheet ions form types of ion velocity distribution functions (VDFs) in the three jets. In one earthward jet, MMS observe cold-ion beams with large velocities parallel to the magnetic fields, and we perform quantitative analysis on the ion VDFs in this jet. The cold ions, together with the hot ions, are reconnection outflow ions and are a minor population in terms of number density inside this jet. The average bulk speed of the cold-ion beams is approximately 38% larger than that of the hot plasma-sheet ions. The cold-ion beams inside the explored jet are about one order of magnitude colder than the hot plasma-sheet ions. These cold-ion beams could be accelerated by the Hall electric field in the cold ion diffusion region and the shrinking magnetic field lines through the Fermi effect.