Observational signatures of electron-driven chromospheric evaporation in a white-light flare

We investigate observational signatures of explosive chromospheric evaporation during a white-light flare (WLF) that occurred on 2022 August 27. Using the moment analysis, bisector techniques, and the Gaussian fitting method, red-shifted velocities of less than 20 km/s are detected in low-temperature spectral lines of Ha, C I and Si IV at the conjugated flare kernels, which could be regarded as downflows caused by chromospheric condensation. Blue-shifted velocities of about 30-40 km/s are found in the high-temperature line of Fe XXI, which can be interpreted as upflows driven by chromospheric evaporation. A nonthermal hard X-ray (HXR) source is co-spatial with one of the flare kernels, and the Doppler velocities are temporally correlated with the HXR fluxes. The nonthermal energy flux is estimated to be at least (1.3+-0.2)*10^10 erg/s/cm^2. The radiation enhancement at Fe I 6569.2 A and 6173 A suggests that the flare is a WLF. Moreover, the while-light emission at Fe I 6569.2 A is temporally and spatially correlated with the blue shift of Fe XXI line, suggesting that both the white-light enhancement and the chromospheric evaporation are triggered and driven by nonthermal electrons. All our observations support the scenario of an electron-driven explosive chromospheric evaporation in the WLF.Comment: The manuscript was accepted for publication in ApJ, and it was a part of the ApJ Focus Issue "Early results from the Chinese Ha Solar Explorer (CHASE)

Effects of Land Use on the Mineralization of Organic Matter in Ultisol

Soil organic matter mineralization changed by land-use types is still not clearly understood. In this study, soils from typical land-use types including adjacent plantations of bamboo (Bam), camphor (Cam), and tea (Tea) were chosen to systematically investigate the role of organic carbon components and microbial community compositions in the organic matter mineralization in Ultisol. The mineralization of organic matter followed the sequence Bam Actinobacteria, Acidobacteria, Firmicutes, and Basidiomycota were significantly different among the land-use types. The multivariate regression tree results showed that the total organic carbon and/or the C/N ratio were dominant factors in influencing the bacterial and fungal communities. Moreover, the redundancy analysis results demonstrated that the communities of bacteria and fungi in Bam, Cam, and Tea were tightly linked to the C/N ratio, the pH and the labile pool I carbon, and the DOM, respectively. The Pearson’s correlation results revealed that the mineralization of organic matter was significantly correlated with the organic carbon components, but generally not the microbial community compositions, which implied that the organic carbon components were perhaps the major determinant in controlling the organic matter mineralization in Ultisol

The macrophage-associated prognostic gene ANXA5 promotes immunotherapy resistance in gastric cancer through angiogenesis

Abstract Gastric cancer (GC) remains a predominant form of malignant tumor globally, necessitating innovative non-surgical therapeutic approaches. This investigation aimed to delineate the expression landscape of macrophage-associated genes in GC and to evaluate their prognostic significance and influence on immunotherapeutic responsiveness. Utilizing the CellMarker2.0 database, we identified 69 immune cell markers with prognostic relevance in GC, including 12 macrophage-specific genes. A Weighted Gene Co-Expression Network Analysis (WGCNA) isolated 3,181 genes correlated with these macrophage markers. The Cancer Genome Atlas (TCGA-STAD) dataset was employed as the training set, while data from the GSE62254 served as the validation cohort. 13 genes were shortlisted through LASSO-Cox regression to formulate a prognostic model. Multivariable Cox regression substantiated that the calculated risk score serves as an imperative independent predictor of overall survival (OS). Distinct macrophage infiltration profiles, pathway associations, treatment susceptibilities, and drug sensitivities were observed between high- and low-risk groups. The preliminary validation of ANXA5 in predicting the survival rates of GC patients at 1 year, 3 years, and 5 years, as well as its expression levels were higher and role in promoting tumor angiogenesis in GC through immunohistochemistry and angiogenesis experiments. In summary, macrophage-related genes were potentially a novel crosstalk mechanism between macrophages and endothelial cells in the tumor microenvironment, and the interplay between inflammation and angiogenesis might have also offered new therapeutic targets, providing a new avenue for personalized treatment interventions

Spectral Observations and Modeling of a Solar White-light Flare Observed by CHASE

The heating mechanisms of solar white-light flares remain unclear. We present an X1.0 white-light flare on 2022 October 2 (SOL2022-10-02T20:25) observed by the Chinese H α Solar Explorer that provides two-dimensional spectra in the visible light for the full solar disk with a seeing-free condition. The flare shows a prominent enhancement of ∼40% in the photospheric Fe i line at 6569.2 Å, and the nearby continuum also exhibits a maximum enhancement of ∼40%. For the continuum near the Fe i line at 6173 Å from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory, it is enhanced up to ∼20%. At the white-light kernels, the Fe i line at 6569.2 Å has a symmetric Gaussian profile that is still in absorption and the H α line at 6562.8 Å displays a very broad emission profile with a central reversal plus a red or blue asymmetry. The white-light kernels are cospatial with the microwave footpoint sources observed by the Expanded Owens Valley Solar Array and the time profile of the white-light emission matches that of the hard X-ray emission above 30 keV from the Gamma-ray Burst Monitor (GBM) on Fermi. These facts indicate that the white-light emission is qualitatively related to a nonthermal electron beam. We also perform a radiative hydrodynamic simulation with the electron-beam parameters constrained by the hard X-ray observations from Fermi/GBM. The result reveals that the white-light enhancement cannot be well explained by a pure electron-beam heating together with its induced radiative backwarming but may need additional heating sources such as Alfvén waves

Calibration procedures for the CHASE/HIS science data

The H{\alpha} line is an important optical line in solar observations containing the information from the photosphere to the chromosphere. To study the mechanisms of solar eruptions and the plasma dynamics in the lower atmosphere, the Chinese H{\alpha} Solar Explorer (CHASE) was launched into a Sun-synchronous orbit on October 14, 2021. The scientific payload of the CHASE satellite is the H{\alpha} Imaging Spectrograph (HIS). The CHASE/HIS acquires, for the first time, seeing-free H{\alpha} spectroscopic observations with high spectral and temporal resolutions. It consists of two observational modes. The raster scanning mode provides full-Sun or region-of-interest spectra at H{\alpha} (6559.7-6565.9 {\AA}) and Fe I (6567.8-6570.6 {\AA}) wavebands. The continuum imaging mode obtains full-Sun photospheric images at around 6689 {\AA}. In this paper, we present detailed calibration procedures for the CHASE/HIS science data, including the dark-field and flat-field correction, slit image curvature correction, wavelength and intensity calibration, and coordinate transformation. The higher-level data products can be directly used for scientific research.Comment: 9 pages, 7 figure