Quantitative Analysis of Seeing with Height and Time at Muztagh-Ata Site Based on ERA5 Database

Seeing is an important index to evaluate the quality of an astronomical site.To estimate seeing at the Muztagh-Ata site with height and time quantitatively,the European Centre for Medium-Range Weather Forecasts reanalysis database(ERA5)is used.Seeing calculated from ERA5 is compared consistently with the Differential Image Motion Monitor seeing at the height of 12 m.Results show that seeing decays exponentially with height at the Muztagh-Ata site.Seeing decays the fastest in fall in 2021 and most slowly with height in summer.The seeing condition is better in fall than in summer.The median value of seeing at 12 m is 0.89 arcsec,the maximum value is1.21 arcsec in August and the minimum is 0.66 arcsec in October.The median value of seeing at 12 m is 0.72arcsec in the nighttime and 1.08 arcsec in the daytime.Seeing is a combination of annual and about biannual variations with the same phase as temperature and wind speed indicating that seeing variation with time is influenced by temperature and wind speed.The Richardson number Ri is used to analyze the atmospheric stability and the variations of seeing are consistent with Ri between layers.These quantitative results can provide an important reference for a telescopic observation strategy.

Chloroquine enhances the cytotoxicity of topotecan by inhibiting autophagy in lung cancer cells

Although the anti-malaria drug chloroquine(CQ) has been shown to enhance chemotherapy and radiation sensitivity in clinical trials,the potential mechanisms underlying this enhancement are still unclear.Here,we examined the relevant mechanisms by which the multipotent CQ enhanced the cytotoxicity of topotecan(TPT).The lung cancer cell line A549 was treated with TPT alone or TPT combined with CQ at non-cytotoxic concentrations.Cell viability was assessed using the MTT assay.The percentage of apoptotic cells and the presence of a side population of cells were both determined by flow cytometry.Autophagy and the expression of Bcl-2 family proteins were examined by Western blotting.The accumulation of YFP-LC3 dots and the formation of acidic vesicular organelles were examined by confocal microscopy.CQ sensitized A549 cells to TPT and enhanced TPT-induced apoptosis in a Bcl-2 family protein-independent fashion.CQ inhibited TPT-induced autophagy,which modified the cytotoxicity of TPT.However,CQ failed to modify the transfer of TPT across the cytoplasmic membrane and did not increase lysosomal permeability.This study showed that CQ at non-cytotoxic concentrations potentiated the cytotoxicity of TPT by interfering with autophagy,implying that CQ has significant potential as a chemotherapeutic enhancer.

Effects of Hydrogen Charging Time and Pressure on the Hydrogen Embrittlement Susceptibility of X52 Pipeline Steel Material

The effects of hydrogen charging time and pressure on the hydrogen embrittlement(HE)susceptibility of X52 pipeline steel material are studied by slow strain rate tensile tests.The fracture morphologies of the specimens are observed by scanning electron microscopy.The HE susceptibility of the X52 pipeline steel material increases with an increase in both hydrogen charging time and hydrogen pressure.At a charging time of 96 h,the HE susceptibility index reaches 45.86%,approximately 3.6 times that at a charging time of 0 h.Similarly,a charging pressure of 4 MPa results in a HE susceptibility index of 31.61%,approximately 2.5 times higher than that at a charging pressure of 0.3 MPa.