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Detection of two bright radio bursts from magnetar SGR 1935 + 2154 期刊论文
Nature Astronomy, 2021, 卷号: 5, 页码: 414
作者: Kirsten, F.; Snelders, M. P.; Jenkins, M.; Nimmo, K.; van den Eijnden, J.

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Astrophysics - High Energy Astrophysical Phenomena Abstract: Fast radio bursts are millisecond-duration, bright radio signals (fluence 0.1-100 Jy ms) emitted from extragalactic sources of unknown physical origin. The recent CHIME/FRB and STARE2 detection of an extremely bright (fluence ~MJy ms) radio burst from the Galactic magnetar SGR 1935+2154 supports the hypothesis that (at least some) fast radio bursts are emitted by magnetars at cosmological distances. In follow-up observations totalling 522.7 h on source, we detect two bright radio bursts with fluences of 112 ± 22 Jy ms and 24 ± 5 Jy ms, respectively. Both bursts appear to be affected by interstellar scattering and we measure significant linear and circular polarization for the fainter burst. The bursts are separated in time by ~1.4 s, suggesting a non-Poissonian, clustered emission processsimilar to those seen in some repeating fast radio bursts. Together with the burst reported by CHIME/FRB and STARE2, as well as a much fainter burst seen by FAST (fluence 60 mJy ms), our observations demonstrate that SGR 1935+2154 can produce bursts with apparent energies spanning roughly seven orders of magnitude, and that the burst rate is comparable across this range. This raises the question of whether these four bursts arise from similar physical processes, and whether the fast radio burst population distribution extends to very low energies (~10³⁰ erg, isotropic equivalent).

黄海桑沟湾水体及沉积物中微塑料污染特征研究 期刊论文
海洋环境科学, 2019, 卷号: 38, 期号: 2, 页码: 198-204
作者: 熊宽旭; 赵新月; 周倩; 付传城; 涂晨

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桑沟湾微塑料潮滩丰度空间分布 Sanggou bay microplastics tidal flats abundance spatial distribution In recent years,research on microplastics pollution in the marine environment has been increasing,but studies on microplastics in water bodies and sediments of the bay under the influence of high-intensity human activities are still rarely reported. In this study,the pollution characteristics of microplastics in the wayer and sediments of Sanggou bay were investigated in December 2017,after the harvest of large-scale aquaculture,with the aim to study the effects of aquaculture activities and hydrodynamics on pollution characteristics and spatial distribution of microplastics in the bay. The results showed that the types of microplastics in the water and sediments of Sanggou bay were mainly fibers,fragments,films,foams and particles. The microplastic abundances in the water and sediments were 1.8 ~ 31.2 N/L,31.2 ~ 1246.8 N/kg,respectively. The average particle sizes of microplastics in water and sediments were 0.51 0.20 mm and 1.54 1.02 mm,respectively. The results of spatial distribution of microplastics in Sanggou bay showed that the high abundance area mainly appears in the inshore waters,and the abundance of microplastics tends to decrease from the inner areas of estuary to the outshore areas. The heterogeneity of microplastic abundance and spatial distribution in Sanggou bay is mainly affected by human activities such as aquaculture,living and shipping,as well as hydrodynamics. In the future,fine sampling and analysis are needed to fully understand the temporal and spatial distribution of microplastics pollution in the bay areas.

烟台牟平海洋牧场季节性低氧对大型底栖动物群落的生态效应 期刊论文
生物多样性, 2019, 卷号: 27, 期号: 2, 页码: 200-210
作者: 李宝泉

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低氧群落结构群落恢复敏感种机会种 hypoxia community structure community recovery sensitive species opportunistic species Hypoxia is a common phenomenon in the world's oceans, especially in the shallow waters of coastal zones. Rates of hypoxia are increasing due to global climatic changes and anthropogenic activities. Hypoxia can cause mass mortality of marine animals and can have severe negative impacts on marine ecosystems. To better understand the effects of hypoxia on macrobenthic communities, a survey was carried out in the Muping Marine Ranch (Yantai) during June, August and September of 2016. Results showed that seasonal hypoxia led to changes in benthic community structure, especially in terms of species composition and dominant species. The dominant species were Polychaeta Lumbrinereis latreilli, Sternaspis scutata and Mollusca Endopleura lubrica in summer. The opportunistic species Lumbrinereis latreilli increased, whereas, sensitive species such as Leptomya minuta, Glycera chirori, Upogebia major, Pontocrates altamarimus, Eriopisella sechellensis decreased during the hypoxic period of August. Hypoxia also reduced biodiversity indices. The effect of hypoxia on abundance and biomass were not significant, mainly because of the increase in the opportunistic Lumbrinereis latreilli, which counteracted the decline in abundance and biomass of other species. Individual physiological tolerance to hypoxia was different among species. Lumbrinereis latreilli showed higher tolerance to hypoxia in dissolved oxygen (DO) = 1.0 mg/L compared to other species. Some sensitive species, such as Leptomya minuta, Upogebia major, Pontocrates altamarimus and Eriopisella sechellensis showed lower tolerance when DO < 2.5 mg/L. When DO increased to 2.5 mg/L, the macrobenthic community start to recover gradually. The recovery extent and time needed were closely related to the degree of seasonal hypoxia.

食用蔬菜能吸收和积累微塑料 期刊论文
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

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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.

Constant cyclotron line energy in Hercules X-1 - Joint Insight-HXMT and NuSTAR observations 期刊论文
Journal of High Energy Astrophysics, 2019, 卷号: 23, 页码: 29-32
作者: HXMT

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Stars: neutron star Pulsars: binary(Her X-1) X-rays: stars Astrophysics - High Energy Astrophysical Phenomena Abstract: The long-term evolution of the centroid energy of the CRSF in Her X-1 is still a mystery. We report a new measurement from a campaign between Insight-HXMT and NuSTAR performed in February 2018. Generally, the two satellites show well consistent results of timing and spectral properties. The joint spectral analysis confirms that the previously observed long decay phase has ended, and that the line energy instead keeps constant around 37.5 keV after flux correction.

Timing analysis of Swift J1658.2-4242's outburst in 2018 with Insight-HXMT, NICER and AstroSat 期刊论文
Journal of High Energy Astrophysics, 2019, 卷号: 24, 页码: 30-40
作者: HXMT

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Accretion accretion disks Black hole physics X-rays: binaries: Swift J1658.2-4242 Astrophysics - High Energy Astrophysical Phenomena Abstract: We present the observational results from a detailed timing analysis of the black hole candidate Swift J1658.2-4242 during its 2018 outburst with the observations of Hard X-ray Modulation Telescope (Insight-HXMT), Neutron Star Interior Composition Explorer (NICER) and AstroSat in 0.1-250 keV. The evolution of intensity, hardness and integrated fractional root mean square (rms) observed by Insight-HXMT and NICER are presented in this paper. Type-C quasi-periodic oscillations (QPOs) observed by NICER (0.8-3.5 Hz) and Insight-HXMT (1-1.6 Hz) are also reported in this work. The features of the QPOs are analyzed with an energy range of 0.5-50 keV. The relations between QPO frequency and other characteristics such as intensity, hardness and QPO rms are carefully studied. The timing and spectral properties indicate that Swift J1658.2-4242 is a black hole binary system. Besides, the rms spectra of the source calculated from the simultaneous observation of Insight-HXMT, NICER and AstroSat support the Lense-Thirring origin of the QPOs. The relation between QPO phase lag and the centroid frequency of Swift J1658.2-4242 reveals a near zero constant when < 4Hz and a soft phase lag at 6.68 Hz. This independence follows the same trend as the high inclination galactic black hole binaries such as MAXI J1659-152.

A New Set of Parameters of High-Mass X-ray Binaries Found with their Cyclotron Lines 期刊论文
arXiv e-prints, 2018
作者: Zhang, Chengmin; Taani, Ali; Chaty, Sylvain; Karino, Shigeyuki; Song, Liming

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Astrophysics - High Energy Astrophysical Phenomena Abstract: We have derived new physical quantities for several High-Mass X-ray Binaries (HMXBs) with supergiant (SG) companions through their cyclotron lines. The parameters are: the terminal velocity of the wind, the mass loss rate of the donor, the effective temperature and the magnetic fields. These parameters influence significantly the improvement of the model of accretion. In spite of the variety of their observational properties, the corresponding magnetic field is around B ~ 10^12 G. This result can be constrained by the effects on stellar evolution. In addition, we have performed a segmentation in the parameter space of donors intended for several SG-HMXB listed in our sample set. The parameter space can be categorized into five regimes depending on the possibility of disk formation associated with accretion from the stellar wind. This can give a quantitative clarification of the observed variability and the properties of these objects. We show that, when these systems come into the direct accretion region, systems with corresponding parameters can emit X-rays.

Correlations between neutrons and protons near the Fermi surface and Q(alpha) of superheavy nuclei 期刊论文
PHYSICAL REVIEW C, 2016, 卷号: 93, 期号: 1, 页码: 14302
作者: Wang, N; Liu, M; Wu, XZ; Meng, J; Wang, N (reprint author), Guangxi Normal Univ, Dept Phys, Guilin 541004, Peoples R China.

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The Shell Corrections And Shell Gaps In Nuclei Are Systematically Studied With The Latest Weizsacker-skyrme (Ws4) Mass Model. We Find That Most Of Asymmetric Nuclei With (Sub) Shell Closures Locate Along The Shell Stability Line (Ssl) n=1.37z+13.5 Which Might Be Due To a Strong Correlation Between Neutrons And proTons Near The Fermi Surface. The Double Magicity Of Nuclei Si-46 And Ni-78 Is Predicted According To The Corresponding Shell Gaps Shell Corrections And Nuclear Deformations. The Unmeasured Superheavy Nuclei (296)118 And (298)120 With Relatively Large Shell Gaps And Shell Corrections Also Locate Along The Ssl Whereas The Traditional Magic Nucleus (298)F1 Evidently Deviates From The Line. The Alpha-decay Energies Of Superheavy Nuclei With Z=113-126 Are Simultaneously Investigated By Using The Ws4 Model togeTher With The Radial Basis Function Corrections. For Superheavy Nuclei With Large Shell Corrections The Smallest Alpha-decay Energy For Elements Z=116 117 And 118 In Their Isotope chaIns LocAtes At N=178 rAther Than 184.

Correlations between neutrons and protons near the Fermi surface and Q(alpha) of superheavy nuclei 期刊论文
PHYSICAL REVIEW C, 2016, 卷号: 93, 期号: 1, 页码: 14302
作者: Wang, N; Liu, M; Wu, XZ; Meng, J

收藏 | 浏览/下载：12/0 | 提交时间：2019/04/08

The shell corrections and shell gaps in nuclei are systematically studied with the latest Weizsacker-Skyrme HEAVIEST NUCLEI (WS4) mass model. We find that most of asymmetric nuclei with (sub) shell closures locate along the shell stability MASSES line (SSL) DEFORMATIONS N=1.37Z+13.5 which might be due to a strong correlation between neutrons and protons near the Fermi surface. The double magicity of nuclei Si-46 and Ni-78 is predicted according to the corresponding shell gaps shell corrections and nuclear deformations. The unmeasured superheavy nuclei (296)118 and (298)120 with relatively large shell gaps and shell corrections also locate along the SSL whereas the traditional magic nucleus (298)F1 evidently deviates from the line. The alpha-decay energies of superheavy nuclei with Z=113-126 are simultaneously investigated by using the WS4 model together with the radial basis function corrections. For superheavy nuclei with large shell corrections the smallest alpha-decay energy for elements Z=116 117 and 118 in their isotope chains locates at N=178 rather than 184.

Mid-late Pleistocene glacial evolution in the Grove Mountains, East Antarctica, constraints from cosmogenic Be-10 surface exposure dating of glacial erratic cobbles 期刊论文
QUATERNARY SCIENCE REVIEWS, 2016, 卷号: 145, 期号: 0, 页码: 71-81
作者: Dong, GC (Dong, Guocheng); Huang, FX (Huang, Feixin); Caffee, MW (Caffee, Marc W.); Huang, FX; Yi, CL (Yi, Chaolu)

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Glacial HisTories From The East Antarctic Ice Sheet (Eais) Provide Keys To UnderstAndIng Correlations Between The Eats And Global Climate. They Are Especially Helpful In The Assessment Of Global Sea Level Change And As a Means Of Quantifying The Magnitude Of pAst Glacial Activity And The RAte At Which Ice Responded To climAte Change. Given The Significance Of Eais Glacial hisTories It Is Imperative That More Glacial Chronologic Data For thIs Region Be Obtained Especially For The Mid-to-lAte Pleistocene. We Report Cosmogenic Be-10 Surface Exposure DAtIng Results From Glacially Transported Cobbles Embedded In Blue-ice moraIne MAterial At Mount hardIng The Grove Mountains Eais. Forty Exotic Cobbles Sampled AlOng Two PrOfiles (a And b) On This Blue-ice MoraIne Present Apparent Exposure-ages RangIng From 7.2 To 542.2 Ka. We Explore This Scattered Dataset By UsIng PrIncipal compOnent Analysis (Pca) To Identify Statistically Significant Trends In The Data. We Identify a correlatiOn betWeen Exposure-age And Distance Of The Cobbles From Mount hardIng. In prOfile a Cobbles Further From Mount HardIng Yield Older Exposure-ages Than Those That Are Relatively Close. In Profile b Cobbles Closer To Mount HardIng Are Found To Have Relatively Older Exposure-ages. In Term Of Glacial hisTory We Suggest That The Direction Of Ice Flow Changed durIng The Period From Similar To 60 To 200 Ka And That Multiple Glacial Fluctuations Occurred In The Mid-late Pleistocene. (c) 2016 Elsevier Ltd. All Rights Reserved.

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