The perihelion of long-period comets places them near the Sun so they may exhibit activity.Before 2013 LU28 reached its perihelion,we performed a continuous observation to detect possible activity.Using the Lijiang 2....The perihelion of long-period comets places them near the Sun so they may exhibit activity.Before 2013 LU28 reached its perihelion,we performed a continuous observation to detect possible activity.Using the Lijiang 2.4 m telescope with a Johnson R filter,we measured the brightness of 2013 LU28 from 2024 January 3 to April 13.The instrumental magnitudes were subsequently transformed into the Pan-STARRS r system.Due to the noticeable descending trend in the absolute magnitude,we verified the cometary activity and constrained some photometric properties of 2013 LU28.Consequently,the increased cross-sectional area had a rate of 42.8 km^(2)day^(−1),and the corresponding mass-loss rate was 2.64 kg s^(−1)with the assumption of a dust-particle size a=10 mm and the densityρ=400 kg m^(−3).We estimated the nucleus radius as 0.11■r_(n)■0.21 km for CO sublimation and 0.20■r_(n)■0.71 km for CO_(2)sublimation and the grain size of 2013 LU28 was ac;117.95μm for CO and ac■7.57μm for CO_(2).The long-term observations provided in this paper will offer significant value for investigating the mechanisms driving the activity of 2013 LU28.展开更多
To examine how low-temperature frost affects tea production in the Dabie Mountains by using Lu an Guapian tea plants as the study material,four groups of temperature treatments were applied in an artificial climate ch...To examine how low-temperature frost affects tea production in the Dabie Mountains by using Lu an Guapian tea plants as the study material,four groups of temperature treatments were applied in an artificial climate chamber to conduct controlled low-temperature experiments,and measurements of leaf photosynthetic and chlorophyll fluorescence parameters were taken to assess the effects of varying low temperatures on photosynthetic performance and fluorescence characteristics.The results show that all low-temperature conditions cause visible leaf damage,with young leaves exhibiting greater sensitivity than mature leaves,and colder temperatures lead to more severe injury.Low temperatures also reduce photosynthetic capacity and fluorescence indicators,and the magnitude of these effects increases as temperature decreases.These impacts ultimately hinder plant growth and negatively affect tea yield and quality.展开更多
基金Funding for the telescope has been provided by CAS and the People’s Government of Yunnan Provincefunded by the Civil Aerospace pre-research project D020302+2 种基金National Natural Science Foundation of China (U12150009,12150009)the CAS Light of West China Programthe science research grants from the China Manned Space Project with NO.CMS-CSST-2021-B10
文摘The perihelion of long-period comets places them near the Sun so they may exhibit activity.Before 2013 LU28 reached its perihelion,we performed a continuous observation to detect possible activity.Using the Lijiang 2.4 m telescope with a Johnson R filter,we measured the brightness of 2013 LU28 from 2024 January 3 to April 13.The instrumental magnitudes were subsequently transformed into the Pan-STARRS r system.Due to the noticeable descending trend in the absolute magnitude,we verified the cometary activity and constrained some photometric properties of 2013 LU28.Consequently,the increased cross-sectional area had a rate of 42.8 km^(2)day^(−1),and the corresponding mass-loss rate was 2.64 kg s^(−1)with the assumption of a dust-particle size a=10 mm and the densityρ=400 kg m^(−3).We estimated the nucleus radius as 0.11■r_(n)■0.21 km for CO sublimation and 0.20■r_(n)■0.71 km for CO_(2)sublimation and the grain size of 2013 LU28 was ac;117.95μm for CO and ac■7.57μm for CO_(2).The long-term observations provided in this paper will offer significant value for investigating the mechanisms driving the activity of 2013 LU28.
基金Supported by the Key Projects in Natural Science Research at the University Level of West Anhui College (WXZR202212).
文摘To examine how low-temperature frost affects tea production in the Dabie Mountains by using Lu an Guapian tea plants as the study material,four groups of temperature treatments were applied in an artificial climate chamber to conduct controlled low-temperature experiments,and measurements of leaf photosynthetic and chlorophyll fluorescence parameters were taken to assess the effects of varying low temperatures on photosynthetic performance and fluorescence characteristics.The results show that all low-temperature conditions cause visible leaf damage,with young leaves exhibiting greater sensitivity than mature leaves,and colder temperatures lead to more severe injury.Low temperatures also reduce photosynthetic capacity and fluorescence indicators,and the magnitude of these effects increases as temperature decreases.These impacts ultimately hinder plant growth and negatively affect tea yield and quality.
