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	No pulsed radio emission during a bursting phase of a Galactic magnetar 期刊论文 OAI收割 Nature, 2020, 卷号: 587, 页码: 63-65 作者: HXMT \| 收藏 \| 浏览/下载：44/0 \| 提交时间：2022/02/08 Astrophysics - High Energy Astrophysical Phenomena Abstract: Fast radio bursts (FRBs) are millisecond-duration radio transients of unknown physical origin observed at extragalactic distances^1-3. It has long been speculated that magnetars are the engine powering repeating bursts from FRB sources^4-13, but no convincing evidence has been collected so far¹⁴. Recently, the Galactic magnetar SRG 1935+2154 entered an active phase by emitting intense soft íray bursts¹⁵. One FRB-like event with two peaks (FRB 200428) and a luminosity slightly lower than the faintest extragalactic FRBs was detected from the source, in association with a soft íray/hard-X-ray flare^18-21. Here we report an eight-hour targeted radio observational campaign comprising four sessions and assisted by multi-wavelength (optical and hard-X-ray) data. During the third session, 29 soft-íray repeater (SGR) bursts were detected in íray energies. Throughout the observing period, we detected no single dispersed pulsed emission coincident with the arrivals of SGR bursts, but unfortunately we were not observing when the FRB was detected. The non-detection places a fluence upper limit that is eight orders of magnitude lower than the fluence of FRB 200428. Our results suggest that FRB-SGR burst associations are rare. FRBs may be highly relativistic and geometrically beamed, or FRB-like events associated with SGR bursts may have narrow spectra and characteristic frequencies outside the observed band. It is also possible that the physical conditions required to achieve coherent radiation in SGR bursts are difficult to satisfy, and that only under extreme conditions could an FRB be associated with an SGR burst.
	食用蔬菜能吸收和积累微塑料期刊论文 OAI收割科学通报, 2019, 卷号: 64, 期号: 9, 页码: 928-934 作者: 李连祯; 周倩; 尹娜; 涂晨; 骆永明 \| 收藏 \| 浏览/下载：142/0 \| 提交时间：2020/06/17 微塑料生菜聚苯乙烯微球吸收积累健康风险 microplastics lettuce polystyrene microbeads uptake accumulation human health risk Microplastic (MP, 100 nm-5 mm) may present an attributable risk to ecosystem and human health, and its pollution has become a global environmental concern. Despite a wealth of information on the accumulation of MPs in aquatic species, there is no information on the uptake and accumulation of MPs by higher plants. Terrestrial edible plants are directly exposed to MPs when agricultural soil was applied with organic manure, sewage sludge as fertilizer or plastic mulching. In this paper, the uptake of two sizes of polystyrene (PS) microbeads (0.2 and 1.0 mum) and then their distribution and migration in an edible plant lettuce were firstly investigated based on laboratory experiments. We used fluorescent markers to track PS microbeads in plant tissues and found fluorescence to be a sensitive and reliable detection method. Sections from untreated control lettuce showed no autofluorescence. When roots were treated with fluorescently labeled PS microbeads, the microbeads could be identified by its fluorescence. Our main study investigated the uptake of 0.2 mum beads, as few luminescence signals were observed in lettuce roots for 1.0 mum beads in our experiment. We observed that 0.2 mum fluorescent microbeads were extracellularly trapped in the root cap mucilage (which is a highly hydrated polysaccharide) and a dark green tip (which was typical of lettuce roots exposed to label PS beads) was usually visible to the naked eye. Confocal images revealed that the PS luminescence signals were mainly located in the vascular system and on the cell walls of the cortex tissue of the roots, indicated that the beads passed through the intercellular space via the apoplastic transport system. Once inside the central cylinder, the 0.2 mum PS beads were transferred from the roots to the stems and leaves via the vascular system following the transpiration stream. We also observed that the PS beads adhered to one another and self-assembled systematically into grape-like and (chain) string-like clusters in the intercellular space of the root and stem vascular tissue of lettuce plant. In contrast to the root and stem, PS beads were dispersed in the leaf tissue. Here, for the first time we provide evidence of the adherence, uptake, accumulation, and translocation of submicrometer MPs within an edible plant. Our findings highlight the previously underappreciated human exposure pathway to MPs through the consumption of contaminated crops and emphasize the need for new management strategies to control the release of MPs waste products into the terrestrial environment. Ultimately, the potential impacts of low range sized MPs on food safety of crop plants and human health need to be urgently considered.
	Changing spring phenology dates in the Three-Rivers Headwater Region of the Tibetan Plateau during 1960-2013 期刊论文 OAI收割 ADVANCES IN ATMOSPHERIC SCIENCES, 2018, 卷号: 35, 期号: 1 特刊: SI, 页码: 116-126 作者: Yu, S (Yu, Shuang); Xia, JJ (Xia, Jiangjiang); Yan, ZW (Yan, Zhongwei); Yang, K (Yang, Kun) \| 收藏 \| 浏览/下载：32/0 \| 提交时间：2019/06/25 Local Growing-season Green-up Dates Vegetation Phenology Temperature Series No Evidence China Climate Variability Winter Cover
	Integrating novel chemical weapons and evolutionarily increased competitive ability in success of a tropical invader 期刊论文 OAI收割 NEW PHYTOLOGIST, 2015, 卷号: 205, 期号: 3, 页码: 1350-1359 Zheng, YL; Feng, YL; Zhang, LK; Callaway, RM; Valiente-Banuet, A; Luo, DQ; Liao, ZY; Lei, YB; Barclay, GF; Silva-Pereyra, C 收藏 \| 浏览/下载：144/0 \| 提交时间：2015/03/26 INVASIVE PLANT CHROMOLAENA-ODORATA CENTAUREA-MACULOSA BIOLOGICAL-CONTROL ENEMY RELEASE NATIVE PLANTS ROOT EXUDATE NO EVIDENCE RANGE ALLELOPATHY