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In situ carbon-coated Co3Se4/CoSe2 (COxSey) nanoparticles (NPs) attached on three-dimensional (3D) reduced graphene oxide (rGO) sheets were skillfully developed in this work, which involved the environment-friendly hydrothermal method, freeze drying, and selenide calcination. Within the structure, the glucose-derived carbon layer exhibited significantly homogeneous dispersion under an argon environment. This structure not only has enhanced stability, but also can effectively mitigate the volume swell of CoxSey particles. The resulted Co3Se4/CoSe2@C/rGO (CSe@C/rGO) exhibited a specific surface area (SSA) of 240.9 m2·g−1, offering more electrochemically active sites for the storage of energy related to lithium ions. The rGO matrix held exceptional flexibility and functional structural rigidity, facilitating the swift ion intercalation and ensuring the high conductivity and recyclability of the structure. When applied to anodes designed for lithium-ion batteries (LIBs), this material demonstrated distinguished rate and ultra-high reversible capacity (872.98 mA·h·g−1 at 0.5 A·g−1). Meanwhile, its capacity retention reached 119.5% after 500 cycles at 2 A·g−1, with a coulombic efficiency of 100%. This work potentially paves the way for generating fast and powerful metal selenide anodes and initiating LIBs with good performance. [ABSTRACT FROM AUTHOR]

Background: After the adjustment of COVID-19 epidemic policy, mainland China experienced two consecutive waves of Omicron variants within a seven-month period. In Guangzhou city, as one of the most populous regions, the viral infection characteristics, molecular epidemiology, and the dynamic of population immunity are still elusive. Methods: We launched a prospective cohort study in the Guangdong Provincial CDC from December 2022 to July 2023. Fifty participants who received the same vaccination regimen and had no previous infection were recruited. Results: 90% of individuals were infected with Omicron BA.5* variants within three weeks in the first wave. Thirteen cases (28.26%) experienced infection with XBB.1* variants, occurring from 14 weeks to 21 weeks after the first wave. BA.5* infections exhibited higher viral loads in nasopharyngeal sites compared to oropharyngeal sites. Compared to BA.5* infections, the XBB.1* infections had significantly milder clinical symptoms, lower viral loads, and shorter durations of virus positivity. The infection with the BA.5* variant elicited varying levels of neutralizing antibodies against XBB.1* among different individuals, even with similar levels of BA.5* antibodies. The level of neutralizing antibodies specific to XBB.1* determined the risk of reinfection. Conclusions: The rapid large-scale infections of the Omicron variants have quickly established herd immunity among the population in mainland China. In the future of the COVID-19 epidemic, a lower infection rate but a longer duration can be expected. Given the large population size and ongoing diversified herd immunity, it remains crucial to closely monitor the molecular epidemiology of SARS-CoV-2 for the emergence of new variants of concern in this region. Additionally, the timely evaluation of the immune status across different age groups is essential for informing future vaccination strategies and intervention policies. [ABSTRACT FROM AUTHOR]

According to the reaming requirement for large diameter directional drilling in hard rock of coal mine roof, the drilling technology of torsional impact rotary reaming is put forward. Based on the simulation results of FLUENT finite element software, the research of small displacement quantification transformation of torsion impactor is carried out, and the working performance of torsion impactor is tested. The relationship of throttle pressure drop, impact torque, throttle nozzle diameter and work displacement is verified. It is proved that the small displacement quantification transformation of torsion impactor can be realized by reducing the throttle nozzle diameter. The combination of rotary reaming tools with torsional impact is designed. The influence factors and calculation methods of reaming parameters such as drilling pressure, pump volume and rotational speed are discussed, and the matching of reaming parameters is improved. On this basis, the field test of rotary reaming drilling with torsional impact is carried out. The test results show that the mechanical drilling efficiency of primary reaming of ?准200 mm drilling hole is up to 10 m/h, which provides the technical basis for efficient reaming of large diameter directional drilling of hard rock in coal mine roof.

The common types and treatment methods of drilling accidents in directional drilling construction are described, and the principle, auxiliary salvage drilling tools, process methods and key points of reverse wire salvage technology are emphatically analyzed. The field practice shows that when the strong rotary pull-up method and casing milling salvage technology can not deal with directional drilling accidents, the reverse wire salvage technology can effectively solve the problem of drilling tools are stuck, and the maximum salvage depth is 1 152 m.