The Initiation Mechanism of the First On-disk X-Class Flare of Solar Cycle 25

In this paper we study the initiation mechanism of the first on-disk X-class eruptive flare in solar cycle 25. Coronal magnetic field reconstructions reveal a magnetic flux rope (MFR) with configuration highly consistent with a filament existing for a long period before the flare, and the eruption of the whole filament indicates that the MFR erupted during the flare. However, quantitative analysis shows that the pre-flare MFR resides in a height too low to trigger a torus instability (TI). The filament experienced a slow rise before the flare onset, for which we estimate evolution of the filament height using a triangulation method by combining the SDO and STEREO observations, and find it is also much lower than the critical height for triggering TI. On the other hand, the pre-flare evolution of the current density shows progressive thinning of a vertical current layer on top of the flare PIL, which suggests that a vertical current sheet forms before the eruption. Meanwhile, there is continuously shearing motion along the PIL under the main branch of the filament, which can drive the coronal field to form such a current sheet. As such, we suggest that the event follows a reconnection-based initiation mechanism as recently established using a high-accuracy MHD simulation, in which an eruption is initiated by reconnection in a current sheet that forms gradually within continuously-sheared magnetic arcade. The eruption should be further driven by TI as the filament quickly rises into the TI domain during the eruption

PSR J1926-0652: A Pulsar with Interesting Emission Properties Discovered at FAST

We describe PSR J1926-0652, a pulsar recently discovered with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Using sensitive single-pulse detections from FAST and long-term timing observations from the Parkes 64-m radio telescope, we probed phenomena on both long and short time scales. The FAST observations covered a wide frequency range from 270 to 800 MHz, enabling individual pulses to be studied in detail. The pulsar exhibits at least four profile components, short-term nulling lasting from 4 to 450 pulses, complex subpulse drifting behaviours and intermittency on scales of tens of minutes. While the average band spacing P3 is relatively constant across different bursts and components, significant variations in the separation of adjacent bands are seen, especially near the beginning and end of a burst. Band shapes and slopes are quite variable, especially for the trailing components and for the shorter bursts. We show that for each burst the last detectable pulse prior to emission ceasing has different properties compared to other pulses. These complexities pose challenges for the classic carousel-type models.Comment: 13pages with 12 figure

Evaluation of the IP-10 mRNA release assay for diagnosis of TB in HIV-infected individuals

HIV-infected individuals are susceptible to Mycobacterium tuberculosis (M.tb) infection and are at high risk of developing active tuberculosis (TB). Interferon-gamma release assays (IGRAs) are auxiliary tools in the diagnosis of TB. However, the performance of IGRAs in HIV-infected individuals is suboptimal, which limits clinical application. Interferon-inducible protein 10 (IP-10) is an alternative biomarker for identifying M.tb infection due to its high expression after stimulation with M.tb antigens. However, whether IP-10 mRNA constitutes a target for the diagnosis of TB in HIV-infected individuals is unknown. Thus, we prospectively enrolled HIV-infected patients with suspected active TB from five hospitals between May 2021 and May 2022, and performed the IGRA test (QFT-GIT) alongside the IP-10 mRNA release assay on peripheral blood. Of the 216 participants, 152 TB patients and 48 non-TB patients with a conclusive diagnosis were included in the final analysis. The number of indeterminate results of IP-10 mRNA release assay (13/200, 6.5%) was significantly lower than that of the QFT-GIT test (42/200, 21.0%) (P = 0.000026). IP-10 mRNA release assay had a sensitivity of 65.3% (95%CI 55.9% – 73.8%) and a specificity of 74.2% (95%CI 55.4% – 88.1%), respectively; while the QFT-GIT test had a sensitivity of 43.2% (95%CI 34.1% – 52.7%) and a specificity of 87.1% (95%CI 70.2% – 96.4%), respectively. The sensitivity of the IP-10 mRNA release assay was significantly higher than that of QFT-GIT test (P = 0.00062), while no significant difference was detected between the specificities of these two tests (P = 0.198). The IP-10 mRNA release assay showed a lower dependence on CD4+ T cells than that of QFT-GIT test. This was evidenced by the fact that the QFT-GIT test had a higher number of indeterminate results and a lower sensitivity when the CD4+ T cells counts were decreased (P < 0.05), while no significant difference in the number of indeterminate results and sensitivity were observed for the IP-10 mRNA release assay among HIV-infected individuals with varied CD4+T cells counts (P > 0.05). Therefore, our study suggested that M.tb specific IP-10 mRNA is a better biomarker for diagnosis of TB in HIV-infected individuals

Research Assessment on the Supply and Demand for Forest Ecosystem Services: The Case of Zhuxi County

A refined assessment of small-scale to medium-scale forest ecosystem services based on the unique geographical conditions of Zhuxi County provides a basis for decision-making to create a regional green development strategy for the county. The specifications for assessing forest ecosystem services (GB/T38582-2020) were followed to calculate the supply of forest ecosystem services in Zhuxi County using the physical quantity method and the value quantity method, and the demand was calculated using the standard value comparison method. The total supply value of forest ecosystem services in 2020 in Zhuxi County was 35,677,894,500 yuan·a−1. In terms of the value of each service, the value of water containment was the largest, accounting for 41.08%, and the value of forest recreation was the smallest, accounting for only 1.36%. The value per unit area of the local broadleaf–mixed forest in Zhuxi County was the largest, at 140,658.65 yuan·a−1, while the value of the fir forest was the smallest, at 89,181.32 yuan·a−1. The comprehensive supply–demand ratio of forest ecosystem services in Zhuxi County was 1.54, which means a moderate surplus; the supply–demand ratio of supply services was 1.27, which means a slight surplus; the supply–demand ratio of adjustment services was 1.34, which means a slight surplus; the supply–demand ratio of support services was 1.13, which means a slight surplus; and the supply–demand ratio of cultural services was 6.01, which means a high surplus. The supply–demand ratio of cultural services of forest ecosystem services in Zhuxi County was the largest and that of the support services was the smallest. From an overall perspective, the supply of forest ecosystem services in Zhuxi County in 2020 was relatively abundant and sufficient to meet local people’s demand for forest ecosystem services. In the future, some goals may include: (1) improving management capacity of forest resources and the quality of forest resources; (2) increasing the value of forest ecological services per unit area; (3) using mixed-forest planting to transform low-value tree species; (4) developing the supply capacity of forest ecological services; (5) enhancing the reprocessing industry of forest products; and (6) expanding the output of nonforest products. A good ecological defence must be established to achieve the sustainable management of forest resources

Microstructure and electrochemical properties of nitrogen-doped DLC films deposited by PECVD technique

Nitrogen-doped diamond-like carbon (N-DLC) films were synthesized by glow discharge plasma enhanced chemical vapor deposition (PECVD) using a hybrid ion beam system. The influence of nitrogen incorporation on the microstructure and electrochemical properties of N-DLC films was investigated by scanning probe microscopy, Raman spectroscopy, X-ray photoemission spectroscopy and cycle voltammetry. Regardless of the deposition parameters, the surface of all the deposited films is very smooth. Raman spectra show that I-D/I-G increases from 0.6 to 1.04 with the substrate bias voltage increases. XPS results identify that carbon is bonded with nitrogen and the substrate bias makes no distinct contribution to the N content in the films, even the N-DLC film at bias of -550V has the lowest N-O bonds concentration and the highest C-N bonds concentration. The film electrodes show the wide potential windows range over 4V, lower background currents in strong acid media. At the bias of -550V, the N-DLC film electrode not only exhibits the Delta E-p at 209 mV and I-p(ox)/I-p(red) at 0.8778 in K3Fe(CN)(6) solution, respectively, but also illustrates a nearly reversible electrode reaction. The mechanism of electroproperties is discussed in terms of the atomic bond structures and diffusion process. (C) 2014 Elsevier B.V. All rights reserved

Insights into friction dependence of carbon nanoparticles as oil-based lubricant additive at amorphous carbon interface

Insights into friction dependence of carbon nanoparticles as oil-based lubricant additive at amorphous carbon interfac