13 research outputs found
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Strong Carbon Features and a Red Early Color in the Underluminous Type Ia SN 2022xkq
We present optical, infrared, ultraviolet, and radio observations of SN 2022xkq, an underluminous fast-declining Type Ia supernova (SN Ia) in NGC 1784 (D ≈ 31 Mpc), from <1 to 180 days after explosion. The high-cadence observations of SN 2022xkq, a photometrically transitional and spectroscopically 91bg-like SN Ia, cover the first days and weeks following explosion, which are critical to distinguishing between explosion scenarios. The early light curve of SN 2022xkq has a red early color and exhibits a flux excess that is more prominent in redder bands; this is the first time such a feature has been seen in a transitional/91bg-like SN Ia. We also present 92 optical and 19 near-infrared (NIR) spectra, beginning 0.4 days after explosion in the optical and 2.6 days after explosion in the NIR. SN 2022xkq exhibits a long-lived C i 1.0693 μm feature that persists until 5 days post-maximum. We also detect C ii λ6580 in the pre-maximum optical spectra. These lines are evidence for unburnt carbon that is difficult to reconcile with the double detonation of a sub-Chandrasekhar mass white dwarf. No existing explosion model can fully explain the photometric and spectroscopic data set of SN 2022xkq, but the considerable breadth of the observations is ideal for furthering our understanding of the processes that produce faint SNe Ia. © 2023. The Author(s). Published by the American Astronomical Society.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
Identifying counterfeit medicines using near infrared spectroscopy
Counterfeit medicines are a growing threat to public health across the world and screening methods are needed to allow their rapid identification. A counterfeiter must duplicate both the physical characteristics and the chemical content of a proprietary product to avoid it being detected as a counterfeit product and this is almost impossible to get right. Counterfeit proprietary medicines are, therefore, relatively easy to identify by near infrared (NIR) spectroscopy which can detect physical as well as chemical differences between products by simple spectral comparison. Identifying generic products is more difficult as they use different excipients in the tablet or capsule matrix. Nevertheless, using appropriate models and a large library, NIR spectroscopy can detect counterfeit generic versions. Detecting sub-standard proprietary medicines can be carried out with NIR spectroscopy models and the most widely used is partial least squares regression (PLSR). General rules for generating accurate quantitative models are easy to describe. Quantifying the active pharmaceutical ingredient (API) in generic products can also be carried out using PLSR models with calibration samples generated by manufacturing laboratory samples or by collecting many generic versions of a medicine so as to obtain a good range of the API content in tablets and capsules. Using hand-held instruments or mobile laboratories allows NIR spectrometers to be taken to places where analyses may be made quickly, rather than taking the samples to a laboratory. This has the enormous advantage that the screening of large numbers of samples may be made in pharmacies and wholesalers. Imaging can bring a whole new dimension to NIR spectroscopy to allow the identification of the API and individual excipients as well as measuring the particle sizes of components and giving a measure of the homogeneity of the matrix. The effect of water on potential misidentifications may be obviated by only using blister-packed samples, having large spectral libraries subjected to different humidities or omitting the spectral region where water absorbs.Peer reviewe
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The James Webb Space Telescope Mission
Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least 4 m. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the 6.5 m James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 yr, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit. © 2023. The Author(s). Published by IOP Publishing Ltd on behalf of the Astronomical Society of the Pacific (ASP). All rights reserved.Open access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]