The effect of 2-chlorophenol (2-CP) on ammonium and nitrite-oxidizing processes was kinetically evaluated in batch cultures with nitrifying sludge at steady state. Assays with ammonium or nitrite as ...energy source and 2.5, 5.0, or 10.0 mg 2-CP-C/l were conducted. Control assays without 2-CP were also performed. Ammonium-oxidizing activity was completely inhibited at the different 2-CP concentrations, whereas nitrite-oxidizing activity was present as nitrite was completely consumed and converted to nitrate irrespectively of 2-CP concentration. In the presence of 2.5 and 5.0 mg 2-CP-C/l, no significant effect on specific rates of nitrite consumption and nitrate production was observed, but a significant decrease on these parameters was observed at 10.0 mg 2-CP-C/l. The nitrifying sludge previously exposed to 2-CP was unable to completely recover its ammonium and nitrite oxidation capacity. Nevertheless, complete 2-CP consumption was achieved in all assays. The effect of 2-CP on ammonium oxidation was observed at kinetic and metabolic pathway level, whereas the effect on nitrite oxidation was observed only at kinetic level. The results obtained in this work evidenced that in order to achieve a successful nitrification process the presence in wastewater of even 2.5 mg 2-CP-C/l should be avoided.
The metabolic and kinetic behavior of a nitrifying sludge exposed to 2-chlorophenol (2-CP) was evaluated in batch cultures. Two kinds of nitrifying culture were used; one acclimated to 4-methylphenol ...(4-mp), and the other unacclimated to 4-mp. The unacclimated culture was affected adversely by the 2-CP's presence, since neither nitrification nor 2-CP oxidation was observed. Nonetheless, the acclimated culture showed metabolic capacity to nitrify and mineralize 2-CP. Ammonium removal was 100%, with a nitrifying yield of 0.92 ± 0.04 mg NO(3)(-)-N/mg NH(4)(+)-N consumed. The consumption efficiency for 2-CP was 100% and the halogenated compound was mineralized to CO2. Denaturing gradient gel electrophoresis (DGGE) patterns showed the shift in microbial community structure, indicating that microbial diversity was due to the acclimation process. This is the first evidence where nitrifying culture acclimated to 4-mp completely removed ammonium and 2-CP.
ABSTRACT
With a unique set of 54 overlapping narrow-band and two broader filters covering the entire optical range, the incoming Javalambre-Physics of the Accelerating Universe Astrophysical Survey ...(J-PAS) will provide a great opportunity for stellar physics and near-field cosmology. In this work, we use the miniJPAS data in 56 J-PAS filters and 4 complementary SDSS-like filters to explore and prove the potential of the J-PAS filter system in characterizing stars and deriving their atmospheric parameters. We obtain estimates for the effective temperature with a good precision (<150 K) from spectral energy distribution fitting. We have constructed the metallicity-dependent stellar loci in 59 colours for the miniJPAS FGK dwarf stars, after correcting certain systematic errors in flat-fielding. The very blue colours, including uJAVA − r, J0378 − r, J0390 − r, uJPAS − r, show the strongest metallicity dependence, around 0.25 mag dex−1. The sensitivities decrease to about 0.1 mag dex−1 for the J0400 − r, J0410 − r, and J0420 − r colours. The locus fitting residuals show peaks at the J0390, J0430, J0510, and J0520 filters, suggesting that individual elemental abundances such as Ca/Fe, C/Fe, and Mg/Fe can also be determined from the J-PAS photometry. Via stellar loci, we have achieved a typical metallicity precision of 0.1 dex. The miniJPAS filters also demonstrate strong potential in discriminating dwarfs and giants, particularly the J0520 and J0510 filters. Our results demonstrate the power of the J-PAS filter system in stellar parameter determinations and the huge potential of the coming J-PAS survey in stellar and Galactic studies.
The shape of the carapace protecting the body of boxfishes has been attributed an important hydrodynamic role in drag reduction and in providing automatic, flow-direction realignment and is therefore ...used in bioinspired design of cars. However, tight swimming-course stabilization is paradoxical given the frequent, high-performance manoeuvring that boxfishes display in their spatially complex, coral reef territories. Here, by performing flow-tank measurements of hydrodynamic drag and yaw moments together with computational fluid dynamics simulations, we reverse several assumptions about the hydrodynamic role of the boxfish carapace. Firstly, despite serving as a model system in aerodynamic design, drag-reduction performance was relatively low compared with more generalized fish morphologies. Secondly, the current theory of course stabilization owing to flow over the boxfish carapace was rejected, as destabilizing moments were found consistently. This solves the boxfish swimming paradox: destabilizing moments enhance manoeuvrability, which is in accordance with the ecological demands for efficient turning and tilting.
We present the abundance analysis for a sample of 7 red giant branch stars in the metal-poor globular cluster NGC 4372 based on UVES spectra acquired as part of the Gaia-ESO Survey. This is the first ...extensive study of this cluster from high-resolution spectroscopy. We derive abundances of O, Na, Mg, Al, Si, Ca, Sc, Ti, Fe, Cr, Ni, Y, Ba, and La. We find a metallicity of Fe/H = −2.19 ± 0.03 and find no evidence of any metallicity spread. This metallicity makes NGC 4372 one of the most metal-poor Galactic globular clusters. We also find an α-enhancement typical of halo globular clusters at this metallicity. Significant spreads are observed in the abundances of light elements. In particular, we find a Na-O anticorrelation. Abundances of O are relatively high compared with other globular clusters. This could indicate that NGC 4372 was formed in an environment with high O for its metallicity. A Mg-Al spread is also present that spans a range of more than 0.5 dex in Al abundances. Na is correlated with Al and Mgabundances at a lower significance level. This pattern suggests that the Mg-Al burning cycle is active. This behavior can also be seen in giant stars of other massive, metal-poor clusters. A relation between light and heavy s-process elements has been identified.
We have performed multiband UBVR
C
I
C
JHK
S
photometry of two young clusters located at large Galactocentric distances in the direction of the Perseus spiral arm. The obtained distances and colour ...excesses amount to 3.9 ± 0.11 kpc, E(B − V) = 0.62 ± 0.05 for Berkeley 94, and 4.3 ± 0.15 kpc, E(B − V) = 0.58 ± 0.06 for Berkeley 96. The respective ages, as measured from the comparison of the upper colour-magnitude diagrams to model isochrones, amount to log10Age(yr) = 7.5 ± 0.07 and 7.0 ± 0.07, respectively. A sequence of optical pre-main-sequence (PMS) members is proposed in both clusters. In addition, samples of objects showing (H − K
S
) excess are found. Part of these are suggested to be PMS cluster members of lower mass than the optical candidates. The spatial distribution of these sources, the comparison to Galactic models and to the expected number of contaminating distant red galaxies, and the spectral energy distribution in particular cases support this suggestion. The spatial distributions shown by members in different mass ranges can be interpreted in terms of the results from numerical simulations. According to these, different initial conditions and evolutionary dynamical paths are suggested for the clusters. Berkeley 94 would have formed under supervirial conditions, and followed the so-called warm collapse model in its evolution, whereas Berkeley 96 would have formed with a subvirial structure, and would have evolved following a cold collapse path. Both processes would be able to reproduce the suggested degree of mass segregation and their spatial distribution by mass range. Finally, the mass distributions of the clusters, from the most massive stars down to PMS stars around 1.3 M, are calculated. An acceptable general agreement with the Salpeter initial mass function slope is found.
Aims. We present the first orbital solution for the O-type supergiant star HD 74194, which is the optical counterpart of the supergiant fast X-ray transient IGR J08408-4503. Methods. We measured the ...radial velocities in the optical spectrum of HD 74194, and we determined the orbital solution for the first time. We also analysed the complex Hα profile. Results. HD 74194 is a binary system composed of an O-type supergiant and a compact object in a short-period (P = 9.5436 ± 0.0002 d) and high-eccentricity (e = 0.63 ± 0.03) orbit. The equivalent width of the Hα line is not modulated entirely with the orbital period, but seems to vary in a superorbital period (P = 285 ± 10 d) nearly 30 times longer than the orbital one.
The GALANTE photometric system Lorenzo-Gutiérrez, A; Alfaro, E J; Maíz Apellániz, J ...
Monthly Notices of the Royal Astronomical Society,
06/2019, Letnik:
486, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract
This paper describes the characterization of the GALANTE photometric system, a seven intermediate- and narrow-band filter system with a wavelength coverage from 3000 Å to 9000 Å. We describe ...the photometric system presenting the full sensitivity curve as a product of the filter sensitivity, CCD, telescope mirror, and atmospheric transmission curves, as well as some first- and second-order moments of this sensitivity function. The GALANTE photometric system is composed of four filters from the J-PLUS photometric system, a twelve broad-to-narrow filter system, and three exclusive filters, specifically designed to measure the physical parameters of stars such as effective temperature Teff, log (g), metallicity, colour excess E(4405 − 5495), and extinction type R5495. Two libraries, the Next Generation Spectral Library (NGSL) and the one presented in Maíz Apellániz & Weiler (2018), have been used to determine the transformation equations between the Sloan Digital Sky Survey (SDSS) ugriz photometry and the GALANTE photometric system. We will use this transformation to calibrate the zero-points of GALANTE images. To this end, a preliminary photometric calibration of GALANTE has been made based on two different griz libraries (SDSS DR12 and ATLAS All-Sky Stellar Reference Catalog, hereinafter RefCat2). A comparison between both zero-points is performed leading us to the choice of RefCat2 as the base catalogue for this calibration, and applied to a field in the Cyg OB2 association.
Context.
The Carina Nebula is one of the major massive star-forming regions in the Galaxy. Its relatively nearby distance (2.35 kpc) makes it an ideal laboratory for the study of massive star ...formation, structure, and evolution, both for individual stars and stellar systems. Thanks to the high-quality spectra provided by the
Gaia
-ESO survey and the LiLiMaRlin library, as well as
Gaia
EDR3 astrometry, a detailed and homogeneous spectroscopic characterization of its massive stellar content can be carried out.
Aims.
Our main objective is to spectroscopically characterize all massive members of the Carina Nebula in the
Gaia
-ESO survey footprint to provide an updated census of massive stars in the region and an updated estimate of the binary fraction of O stars.
Methods.
We performed accurate spectral classification using an interactive code that compares spectra with spectral libraries of OB standard stars, as well as line-based classic methods. We calculated membership using our own algorithm based on
Gaia
EDR3 astrometry. To check the correlation between the spectroscopic n-qualifier and the rotational velocity, we used a semi-automated tool for the line-broadening characterization of OB stars based on a combined Fourier transform and goodness-of-fit methodology.
Results.
The
Gaia
-ESO survey sample of massive OB stars in the Carina Nebula consists of 234 stars. The addition of brighter sources from the Galactic O-Star Spectroscopic Survey and additional sources from the literature allows us to create the most complete census of massive OB stars so far in the region. It contains a total of 316 stars, with 18 of them in the background and 4 in the foreground. Of the 294 stellar systems in Car OB1, 74 are of O type, 214 are of nonsupergiant B type, and 6 are of WR or nonO supergiant (II to Ia) spectral class. We identify 20 spectroscopic binary systems with an O-star primary, of which 6 are reported for the first time, and another 18 with a B-star primary, of which 13 are new detections. The average observed double-lined binary fraction of O-type stars in the surveyed region is 0.35, which represents a lower limit. We find a good correlation between the spectroscopic n-qualifier and the projected rotational velocity of the stars. The fraction of candidate runaways among the stars with and without the n-qualifier is 4.4% and 2.4%, respectively, although nonresolved double-lined binaries could be contaminating the sample of fast rotators.
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