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Spectroscopic study of Be-shell stars:4 Her and 88 Her

research in Astronomy and Astrophysics 2016年第5期16卷 47-58页

作者： Shruthi S Bhat Paul KT Annapumi Subramaniam Blesson Mathew Department of Physics Christ UniversityBangalore 560029India Indian Institute of Astrophysics II BlockKormangalaBangalore 560034India Department of Astronomy&Astrophysics Tata Institute of Fundamental ResearchHomi Bhabha RoadMumbai400005India

We present an optical spectroscopic study based on 41 spectra of 4 Her and 32 spectra of 88 Her, obtained over a period of 6 months. We estimate the rotational velocity of these stars from HeI lines in the blue spectral region （4000-4500 A）. We find that these stars are likely to be rotating at a fractional critical rotation of -0.80. We measure the average Ip/lc ratio to quantify the strength of the Ha line and obtain 1.63 for 4 Her and 2.06 for 88 Her. The radius of the Ha emission region is estimated to be Ra/R. -5.0, assuming a Keplerian disk. These stars are thus found to be fast rotators with a relatively small Hoe emission region. We detect V/R variation of the Ha spectral line during the observed period. We re-estimate the periods for both stars and obtain a period of ,-46 d and its harmonic of 23.095 d for 4 Her, and a period of -86 d for 88 Her. As these two cases are shell stars with binaries and have low Ha EW with the emission region closer to the central star, the V/R variation and a change in period may be an effect of the binary on the circumstellar disk.

关键词： stars: emission-line Be -- circumstellar matter -- stars: individual (4 Her 88 Her) -- stars:rotation -- techniques: spectroscopic

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Valorization of agro-industrial fruit peel waste to fluorescent nanocarbon sensor:Ultrasensitive detection of potentially hazardous tropane alkaloid

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Frontiers of Environmental Science & Engineering 2022年第3期16卷 1-11页

作者： Athiyanam Venkatesan Ramya Manoj Balachandran Nanocarbon research Group Materials Science Research LaboratoryDepartment of Physics and ElectronicsCHRIST(Deemed to be University)Bengaluru-560029KarnatakaIndia

Millions of tonnes of agro-industrial waste are generated each year globally,with the vast majority of it going untreated,underutilized,and disposed of by burning or landfilling,causing severe environmental distress and economic downturn.A practical solution to this global issue is to use green chemistry to convert this waste into value-added ***,in the present study,agro-industrial orange peel waste was valorized into fluorescent nanodiamond-like carbon sensor via a green route involving hydrothermal treatment of microwave carbonized orange peel *** developed sensor,used for the fluorescence detection of potentially hazardous drug atropine sulfate,exhibits unique dual linearity over concentration ranges of 300 nM to 1 M and from 1 M to 10 M,as well as ultra-low sensitivity of 34.42 nM and 356.46 nM,***,the sensor demonstrates excellent reproducibility,high stability,and satisfactory recovery when used to identify and quantify atropine sulfate in biological samples and commercially available pharmaceuticals,indicating promising multidisciplinary applications.

关键词： Agro-industrial waste Orange peel Valorization Nanodiamond-like carbon Atropine sulphate Fluorescence sensing

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Broadband Spectral Properties of MAXI J1348-630 using AstroSat Observations

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research in Astronomy and Astrophysics 2023年第1期23卷 161-170页

作者： Gitika Mall Jithesh Vadakkumthani Ranjeev Misra Center for Field Theory and Particle Physics and Department of Physics Fudan UniversityShanghai 200438China Department of Physics and Electronics CHRIST(Deemed to be University)Hosur Main RoadBengaluru 560029India Inter-University centre for Astronomy and Astrophysics(IUCAA) PB No.4GaneshkhindPune 411007India

We present broadband X-ray spectral analysis of the black hole X-ray binary MAXI J1348-630,performed using five AstroSat *** source was in the soft spectral state for the first three observations and in the hard state for the last *** three soft state spectra were modeled using a relativistic thin accretion disk with reflection features and thermal *** fitting of the soft state spectra constrained the spin parameter of the black hole a_(*)>0.97 and the disk inclination angle i=32.9_(-0.6)^(+4.1)*** bright and faint hard states had bolometric flux a factor of~6 and~10 less than that of the soft state *** spectra were fitted using the same model except that the inner disk radius was not assumed to be at the last stable ***,the estimated values do not indicate large truncation radii and the inferred accretion rate in the disk was an order of magnitude lower than that of the soft *** with earlier reported temporal analysis,AstroS at data provide a comprehensive picture of the evolution of the source.

关键词： black hole physics-X-rays binaries-accretion-accretion disks-X-rays individual(MAXI J1348-630)

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States,Nations,and Civilizations

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Fudan Journal of the Humanities and Social Sciences 2021年第2期14卷 225-242页

作者： Göran Therborn University of Cambridge CambridgeUK

Nation-states are inherently part of cultural formations,sustaining,legitimating,and inspiring *** nations sustaining contemporary states are very different,and major routes of historical nation-state formation can be... 详细信息

关键词： Nation Civilization(s) Nation-states Civilization states Modernity

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