| 1. |
- Blanton, Michael R., et al.
(författare)
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Sloan Digital Sky Survey IV : Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
- 2017
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Ingår i: Astronomical Journal. - : IOP Publishing Ltd. - 0004-6256 .- 1538-3881. ; 154:1
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Tidskriftsartikel (refereegranskat)abstract
- We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and. high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median z similar to 0.03). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between z similar to 0.6 and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs. and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the. Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July.
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| 2. |
- Cunha, Katia, et al.
(författare)
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Adding the s-Process Element Cerium to the APOGEE Survey : Identification and Characterization of Ce II Lines in the H-band Spectral Window
- 2017
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Ingår i: Astrophysical Journal. - : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 844:2
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Tidskriftsartikel (refereegranskat)abstract
- Nine Ce II lines have been identified and characterized within the spectral window observed by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey (between lambda 1.51 and 1.69 mu m). At solar metallicities, cerium is an element that is produced predominantly as a result of the slow capture of neutrons (the s-process) during asymptotic giant branch stellar evolution. The Ce II lines were identified using a combination of a high-resolution (R = lambda/delta lambda = 100,000) Fourier Transform Spectrometer (FTS) spectrum of a Boo and an APOGEE spectrum (R. =. 22,400) of a metal-poor, but s-process enriched, red giant (2M16011638-1201525). Laboratory oscillator strengths are not available for these lines. Astrophysical gf-values were derived using alpha Boo as a standard star, with the absolute cerium abundance in alpha Boo set by using optical Ce II lines that have precise published laboratory gf-values. The near-infrared Ce II lines identified here are also analyzed, as consistency checks, in a small number of bright red giants using archival FTS spectra, as well as a small sample of APOGEE red giants, including two members of the open cluster NGC 6819, two field stars, and seven metal-poor N-and Al-rich stars. The conclusion is that this set of Ce II lines can be detected and analyzed in a large fraction of the APOGEE red giant sample and will be useful for probing chemical evolution of the s-process products in various populations of the Milky Way.
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| 3. |
- Rezzadori, Katia, et al.
(författare)
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Characterization and performance of reverse osmosis and nanofiltration membranes submitted to subcritical and supercritical CO2
- 2017
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Ingår i: Journal of Supercritical Fluids. - : ELSEVIER SCIENCE BV. - 0896-8446 .- 1872-8162. ; 128, s. 39-46
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Tidskriftsartikel (refereegranskat)abstract
- Behavior of nanofiltration (NF270 and NP030) and reverse osmosis (BW30 and ORAK) polymeric membranes in systems with dense CO2 was evaluated. The influence of transmembrane pressure on the CO2 permeate flux at subcritical and supercritical conditions was assessed and membrane characterization (FTIR-ATR, zeta potential, Hansen’s solubility parameters) was performed. The results of CO2 permeation suggest that selectivity of polymeric matrix depends, in great extent, on the interaction between solvent and polymer. This behavior corroborates with the presence of hysteresis phenomenon in permeability curves and solubility results. Also, zeta potential showed a decrease in the membrane point of zero charge (PZC) after pressurization/depressurization cycle, suggesting possible CO2 sorption in the membrane polymer. Nevertheless, the oil retention for NP030 and ORAK membranes was up to 85% and no damage to the membrane structure was found. Both membranes presented potential for concentration of fatty acids under dense phase CO2.
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| 4. |
- Zanatta, Vanessa, et al.
(författare)
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Stability of oil-in-water emulsions produced by membrane emulsification with microporous ceramic membranes
- 2017
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Ingår i: Journal of Food Engineering. - : ELSEVIER SCI LTD. - 0260-8774 .- 1873-5770. ; 195, s. 73-84
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Tidskriftsartikel (refereegranskat)abstract
- Membrane emulsification has been drawing attention due to its many application possibilities. This study aimed to assess the preparation and stability of oil in water (O/W) emulsions by membrane emulsification technique. Microporous ceramic membranes with mean pore size 0.2 mu m and 0.8 mu m were used for producing sunflower oil in water emulsions, displaying mean droplet size ranging from 2.9 to 11.6 mu m and from 4.8 to 16.2 mu m, respectively. The effect of the oil concentration (10%-20%), surfactant concentration (1%-4%), tangential velocity (0.12 m s(-1) to 0.24 m s(-1)), and feed pressure (100 kPa-300 kPa) on the process performance was investigated using an experimental design. All the parameters significantly influenced the mean droplet size, the droplet size distribution, and the emulsion stability. Depending on the emulsification conditions, monodisperse and polydisperse emulsions were obtained. The use of a membrane with 0.2 mu m mean pore size led to better results than those obtained with a 0.8 mu m membrane, since they yielded emulsions displaying smaller droplet size and narrower size distribution. The emulsions prepared using this membrane were stable up to 100 days. (C) 2016 Elsevier Ltd. All rights reserved.
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