An Atypical Plateau-like Extreme-ultraviolet Late-phase Solar Flare Driven by the Non-radial Eruption of a Magnetic Flux Rope

Recent observations in extreme-ultraviolet (EUV) wavelengths reveal an EUV late phase in some solar flares, which is characterized by a second peak in the warm coronal emissions (about 3 MK) occurring several tens of minutes to a few hours after the corresponding main flare peak. We aim to clarify the physical origin of an atypical plateau-like EUV late phase in an X1.8-class solar flare occurring on 2011 September 7 from active region (AR) 11283. We first characterize the plateau-like late phase using EUV Variability Experiment (EVE) full-disk integrated irradiance observations and Atmospheric Imaging Assembly (AIA) spatially-resolved imaging observations on board the Solar Dynamics Observatory (SDO). Then we perform a nonlinear force-free-field (NLFFF) extrapolation, from which a filament-hosting magnetic flux rope (MFR) is revealed. The eruption of the MFR is tracked both in the plane of the sky (POS) and along the line of sight (LOS) through visual inspection and spectral fitting, respectively. Finally, we carry out differential emission measure (DEM) analysis to explore the thermodynamics of the late-phase loops. The MFR shows a non-radial eruption from a fan-spine magnetic structure. The eruption of the MFR and its interaction with overlying arcades invoke multiple magnetic reconnections, which are responsible for the production of different groups of late-phase loops. Afterwards, the late-phase loops enter a long-lasting cooling stage, appearing sequentially in AIA passbands of decreasing response temperatures. Due to their different lengths, the different groups of late-phase loops cool down at different cooling rates, which makes their warm coronal emission peaks temporally separated from each other. Combing the emissions from all late-phase loops together, an elongated plateau-like late phase is formed.Comment: Accepted by A&

Observations of a Failed Solar Filament Eruption Involving External Reconnection

We report a failed solar filament eruption that involves external magnetic reconnection in a quadrupolar magnetic configuration. The evolution exhibits three kinematic evolution phases: a slow-rise phase, an acceleration phase, and a deceleration phase. In the early slow rise, extreme-ultraviolet (EUV) brightenings appear at the expected null point above the filament and are connected to the outer polarities by the hot loops, indicating the occurrence of a breakout reconnection. Subsequently, the filament is accelerated outward, accompanied by the formation of low-lying high-temperature post-flare loops ($>$ 15 MK), complying with the standard flare model. However, after 2--3 minutes, the erupting filament starts to decelerate and is finally confined in the corona. The important finding is that the confinement is closely related to an external reconnection as evidenced by the formation of high-lying large-scale hot loops ($>$ 10 MK) with their brightened footpoints at the outer polarities, the filament fragmentation and subsequent falling along the newly formed large-scale loops, as well as a hard X-ray source close to one of the outer footpoint brightenings. We propose that, even though the initial breakout reconnection and subsequent flare reconnection commence and accelerate the filament eruption, the following external reconnection between the erupting flux rope and overlying field, as driven by the upward filament eruption, makes the eruption finally failed, as validated by the numerical simulation of a failed flux rope eruption.Comment: Accepted by Ap

A discussion of inner south projection angle for performance analysis of dielectric compound parabolic concentrator

In the performance analysis of a trough compound parabolic concentrator (CPC), the concept of south projection angle is often used for the nonmeridional sunlight to compare with the acceptance angle of CPC to determine if solar radiation could be collected. The solar altitude and azimuth are the only two factors used to calculate the south projection angle. However, for the solid CPC made of dielectric material, due to the refraction on the air–dielectric interface, the optical path of refracted light within a dielectric CPC would also depend on the refractive index of dielectric material and the tilt angle of CPC. The conventional south projection angle would not be suitable for performance analysis of a solid dielectric CPC. This paper therefore introduces a concept of inner south projection angle which is based on the refracted light and derives a formula using vector analysis. The formula relates the inner south project angle with the solar altitude and azimuth, the refractive index, and the CPC tilt angle as well. Photopia software is meanwhile employed to predict the optical performance of dielectric CPC. The simulation results confirm that use of the inner south projection angle can determine if solar radiation could be collected or transmitted through a dielectric CPC rather than conventional south projection angle. Discussions are given about the correlation between the inner south projection angle and the optical efficiency and transmittance of a trough dielectric CPC. This provides a convenient way to evaluate the performance of a dielectric CPC over a period such as a whole year

3,5-Dinitro-N-(4-nitro­phen­yl)benzamide

In the title mol­ecule, C13H8N4O7, the amide fragment has an anti configuration. The mean planes of the two benzene rings form a dihedral angle of 7.78 (4)°. The mean planes of the three nitro groups are twisted by 6.82 (3), 5.01 (4) and 18.94 (7)° with respect to the benzene rings to which they are attached. In the crystal, mol­ecules are linked by weak inter­molecular N—H⋯O hydrogen bonds into chains along [100]

N,N′-Bis(2,5-dichloro­phen­yl)isophthalamide

The asymmetric unit of the title compound, C20H12Cl4N2O2, contains one half-mol­ecule with a center of symmetry along a C⋯C axis of the central benzene ring. The two C=O groups adopt an anti orientation and the two amide groups are twisted away from the central benzene ring by 27.38 (3) and 27.62 (4)°. The mean planes of the dichloro-substituted benzene rings are twisted by 7.95 (4)° with respect to the benzene ring. The crystal packing is stabilized by weak inter­molecular N—H⋯O inter­actions

A study on use of miniature dielectric compound parabolic concentrator (dCPC) for daylighting control application

Low-concentration solid dielectric compound parabolic concentrator (dCPC) and its variations have been widely regarded as an attractive solution to reduce the cost of a photovoltaic (PV) system, particularly for building-integrated application. Different from a mirror CPC, a dCPC allows the light beyond its acceptance angle to penetrate through its lateral surface. This escaped light could be actually used for daylighting, so the dCPC offers a potential for combined PV and daylighting application suitable for the atrium buildings or large green houses. In the modern buildings, an advanced daylighting system such as prismatic panels is used to balance between harvesting daylight and preventing excessive solar heat gain. In contrast, this study aims to evaluate the advantage of the miniature solid dCPC over common prismatic structures according to their daylight transmittance values under both standard and real sky conditions. A commercial optical analysis software PHOTOPIA is firstly used to compare the daylighting control performance between a dCPC rod and two common prismatic elements. The effect of solar altitude and azimuth angles changing with time is considered. A preliminary test under a solar simulator and a real sky condition is also introduced to provide experimental evidence regarding the advantageous feature of a dCPC rod for daylighting control

Inhibition of Aldose Reductase Activates Hepatic Peroxisome Proliferator-Activated Receptor-α and Ameliorates Hepatosteatosis in Diabetic db/db Mice

We previously demonstrated in streptozotocin-induced diabetic mice that deficiency or inhibition of aldose reductase (AR) caused significant dephosphorylation of hepatic transcriptional factor PPARα, leading to its activation and significant reductions in serum lipid levels. Herein, we report that inhibition of AR by zopolrestat or by a short-hairpin RNA (shRNA) against AR caused a significant reduction in serum and hepatic triglycerides levels in 10-week old diabetic db/db mice. Meanwhile, hyperglycemia-induced phosphorylation of hepatic ERK1/2 and PPARα was significantly attenuated in db/db mice treated with zopolrestat or AR shRNA. Further, in comparison with the untreated db/db mice, the hepatic mRNA expression of Aco and ApoA5, two target genes for PPARα, was increased by 93% (P < 0.05) and 73% (P < 0.05) in zopolrestat-treated mice, respectively. Together, these data indicate that inhibition of AR might lead to significant amelioration in hyperglycemia-induced dyslipidemia and nonalcoholic fatty liver disease

A novel solar multifunctional PV/T/D system for green building roofs

A novel transparent roof which is made of solid CPC (Compound Parabolic Concentrator) PV/T/D (Photovoltaic/Thermal/Day lighting) system is presented. It combines the solar PV/T/D system with green building design. The PV/T/D system can achieve excellent light control at noon and adjust the thermal environment in the building, such that high efficiency utilization of solar energy could be achieved in modern architecture. This kind of roof can increase the visual comfort for building occupants; it can also avoid the building interior from overheating and dazzling at noon which is caused by direct sunlight through transparent roof. Optical simulation software is used to track the light path in different incidence angles. CFD (Computational Fluid Dynamics) simulation and steady state experiment have been taken to investigate the thermal characteristic of PV/T/D device. Finally, the PV/T/D experimental system was built; and the PV efficiency, light transmittance and air heating power of the system are tested under real sky conditions