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近海环境中抗生素分析样品前处理技术的研究进展 期刊论文 OAI收割
色谱, 2020, 卷号: 38, 期号: 1, 页码: 95-103
作者: 吕敏; 陈令新

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抗生素近海前处理技术综述 antibiotics coastal pretreatment techniques review The widespread and massive usage of antibiotics for the prevention and treatment of diseases in human and animals have resulted in their continuous discharge into the environment, and finally, into the coastal environment through various pathways. Accumulation of antibiotics in aquatic organisms poses a great threat to ecological and human health, especially because it facilitates the generation and spread of bacterial resistance. Given the diverse range of antibiotics with various features, as well as their presence at low concentrations in the environment, it is imperative to develop pretreatment techniques for antibiotics in various matrices. In this paper, the pretreatment methods proposed in recent decades for antibiotics in coastal water, sediment, and biota are summarized, with emphasis on commonly used methods such as solid-phase extraction, solid-liquid extraction, matrix solid-phase dispersion, and QuEChERS. Additionally, the potential factors influencing the extraction performance and clean-up efficiency are analyzed. The advantages and disadvantages of the methods and their development are finally discussed.

Insight-HXMT observations of Swift J0243.6+6124: the evolution of RMS pulse fractions at super-Eddington luminosity 期刊论文 OAI收割
Monthly Notices of the Royal Astronomical Society, 2020, 卷号: 497, 页码: 5498-5506
作者: HXMT

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stars: neutron pulsars: individual: Swift J0243.6+6124 X-rays: binaries Astrophysics - High Energy Astrophysical Phenomena Abstract: Based on Insight-HXMT data, we report on the pulse fraction evolution during the 2017-2018 outburst of the newly discovered first Galactic ultraluminous X-ray (ULX) source Swift J0243.6+6124. The pulse fractions of 19 observation pairs selected in the rising and fading phases with similar luminosity are investigated. The results show a general trend of the pulse fraction increasing with luminosity and energy at supercritical luminosity. However, the relative strength of the pulsation between each pair evolves strongly with luminosity. The pulse fraction in the rising phase is larger at luminosity below 7.71 × 10³⁸ erg s^-1, but smaller at above. A transition luminosity is found to be energy independent. Such a phenomenon is first confirmed by Insight-HXMT observations and we speculate that it may have relation with the radiation-pressure-dominated accretion disc.

An underlying clock in the extreme flip-flop state transitions of the black hole transient Swift J1658.2-4242 期刊论文 OAI收割
Astronomy and Astrophysics, 2020, 卷号: 641, 页码: A101
作者: HXMT

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accretion accretion disks black hole physics X-rays: binaries time Astrophysics - High Energy Astrophysical Phenomena Abstract:
Aims: Flip-flops are top-hat-like X-ray flux variations, which have been observed in some transient accreting black hole binary systems, and feature simultaneous changes in the spectral hardness and the power density spectrum (PDS). They occur at a crucial time in the evolution of these systems, when the accretion disc emission starts to dominate over coronal emission. Flip-flops remain a poorly understood phenomenon, so we aim to thoroughly investigate them in a system featuring several such transitions.
Methods: Within the multitude of observations of Swift J1658.2-4242 during its outburst in early 2018, we detected 15 flip-flops, enabling a detailed analysis of their individual properties and the differences between them. We present observations by XMM-Newton, NuSTAR, Astrosat, Swift, Insight-HXMT, INTEGRAL, and ATCA. We analysed their light curves, searched for periodicities, computed their PDSs, and fitted their X-ray spectra, to investigate the source behaviour during flip-flop transitions and how the interval featuring flip-flops differs from the rest of the outburst.
Results: The flip-flops of Swift J1658.2-4242 are of an extreme variety, exhibiting flux differences of up to 77% within 100 s, which is much larger than what has been seen previously. We observed radical changes in the PDS simultaneous with the sharp flux variations, featuring transitions between the quasi-periodic oscillation types C and A, which have never been observed before. Changes in the PDS are delayed, but more rapid than changes in the light curve. Flip-flops occur in two intervals within the outburst, separated by about two weeks in which these phenomena were not seen. Transitions between the two flip-flop states occurred at random integer multiples of a fundamental period of 2.761 ks in the first interval and 2.61 ks in the second. Spectral analysis reveals the high and low flux flip-flop states to be very similar, but distinct from intervals lacking flip-flops. A change of the inner temperature of the accretion disc is responsible for most of the flux difference in the flip-flops. We also highlight the importance of correcting for the influence of the dust scattering halo on the X-ray spectra.

GRB 200415A: A Short Gamma-Ray Burst from a Magnetar Giant Flare? 期刊论文 OAI收割
The Astrophysical Journal, 2020, 卷号: 899, 页码: 106
作者: HXMT

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Gamma-ray bursts Soft gamma-ray repeaters Magnetars Gamma-ray transient sources 629 1441 992 1853 Astrophysics - High Energy Astrophysical Phenomena Abstract: The giant flares of soft gamma-ray repeaters (SGRs) have long been proposed to contribute to at least a subsample of the observed short gamma-ray bursts (GRBs). In this paper, we perform a comprehensive analysis of the high-energy data of the recent bright short GRB 200415A, which was located close to the Sculptor galaxy. Our results suggest that a magnetar giant flare provides the most natural explanation for most observational properties of GRB 200415A, including its location, temporal and spectral features, energy, statistical correlations, and high-energy emissions. On the other hand, the compact star merger GRB model is found to have difficulty reproducing such an event in a nearby distance. Future detections and follow-up observations of similar events are essential to firmly establish the connection between SGR giant flares and a subsample of nearby short GRBs.

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 OAI收割
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 OAI收割
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.

Timing analysis of Swift J1658.2-4242's outburst in 2018 with Insight-HXMT, NICER and AstroSat 期刊论文 OAI收割
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 method to estimate the neutral atmospheric density near the ionospheric main peak of Mars 期刊论文 OAI收割
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 2016, 卷号: 121, 期号: 4, 页码: 3464-3475
作者: Zou, Hong; Ye, Yu Guang; Wang, Jin Song; Nielsen, Erling; Cui, Jun

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The neutral densities at 130 km can be derived fromtheMGS/RS measurements with our method The derived neutral densities can be used to verify or calibrate the Martian atmospheric model The method can be applied to other radio occultation measurements such as MEX/RS measurements

Structural design of large aperture rectangular mirror for space telescope (EI CONFERENCE) 会议论文 OAI收割
2nd International Conference on Civil Engineering and Transportation, ICCET 2012, October 27, 2012 - October 28, 2012, Guilin, China
作者: Li Z.; Li Z.

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Structural design of large aperture mirror is one of the key technologies for space telescope development. To meet the requirements of high stiffness strength and thermal dimensional stability some factors such as support scheme materials selection lightweight design and flexible support design were taken into account. The three supports location of the mirror was determined according to the modal analytical solution. By adjusting the parameters of flexure hinge influences of gravity assembly stress and thermal stress on the mirror were reduced obviously. Finite element analysis (FEA) results indicate that the surface accuracy reach to rms10.2nm and 10.8nm under the gravity along optical axis direction and 5C uniform temperature rise respectively the fundamental frequency of the mirror component is 268Hz. Dynamics test shows that the first order natural frequency is 256Hz which shows an error less than 5% compared to FEA results. (2013) Trans Tech Publications Switzerland.

Laser cleaning of neutral attenuator plate based on low power laser diode (EI CONFERENCE) 会议论文 OAI收割
2nd International Conference on Energy, Environment and Sustainable Development, EESD 2012, October 12, 2012 - October 14, 2012, Jilin, China
作者: Chen Y.; Li L.

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Laser cleaning is a non-contact green and environmental cleaning method which can effectively remove particulate contaminations of sizes as small as 0.1 m without damage to the optics. But most laser cleaning devices are large and heavy also expensive due to using large lasers such as CO2 laser YAG Laser etc. In this work a low power LD was tried to clean fingerprint and dust contaminated on the surface of the attenuator glasses plates. In the laser cleaning experiment with low power diode the fingerprint grease can be efficient to be cleaned but there is no evident effect for cleaning inorganic dust. The cleaning different degree of fingerprint contaminations was investigated at the variable laser parameters including laser power and irradiation time. An optical microscope was used to analyze the cleaning effect. The results show that low power LD can effectively remove the fingerprint on the surface of absorptive-type attenuator glass plates. On the premise that the attenuator optics glasses are not damaged the cleaning area increases with the increase of radiation time and laser power. The cleaning area doesn't change much with the variation of laser frequency when the other parameters are the same. (2013) Trans Tech Publications Switzerland.