302 research outputs found
Self-consistent physical parameters for MC clusters from CMD modelling: application to SMC clusters observed with the SOAR telescope
The Magellanic Clouds (MCs) present a rich system of stellar clusters that
can be used to probe the dynamical and chemical evolution of these neighboring
and interacting irregular galaxies. In particular, these stellar clusters (SCs)
present combinations of age and metallicity that are not found for this class
of objects in the Milky Way, being therefore very useful templates to test and
to calibrate integrated light simple stellar population (SSP) models applied to
unresolved distance galaxies. On its turn, the age and metallicity for a
cluster can be determined spatially resolving its stars, by means of analysis
of its colour-magnitude diagrams (CMDs). In this work we present our method to
determine self-consistent physical parameters (age, metallicity, distance
modulus and reddening) for a stellar cluster, from CMDs modelling of relatively
unstudied SCs in the Small Magellanic Cloud (SMC) imaged in the BVI filters
with the 4.1 m SOAR telescope. Our preliminary results confirm our expectations
that come from a previous integrated spectra and colour analysis: at least one
of them (Lindsay 2) is an intermediate-age stellar cluster with ~ 2.6 Gyr and
[Fe/H] ~ -1.3, being therefore a new interesting witness regarding the
reactivation of the star formation in the MCs in the last 4 Gyr.Comment: 4 pages, 2 figures. To be published in the proceedings of IAUS256:
The Magellanic System: Stars, Gas, and Galaxie
FORS2/VLT survey of Milky Way globular clusters II. Fe and Mg abundances of 51 Milky Way globular clusters on a homogeneous scale
Homogeneous metallicities and radial velocities for Galactic globular clusters II. New CaT metallicities for 28 distant and reddened globular clusters
Although the globular clusters in the Milky Way have been studied for a long time, a significant fraction of them lack homogeneous metallicity and radial velocity measurements. In an earlier paper we presented the first part of a project to obtain metallicities and radial
velocities of Galactic globular clusters from multiobject spectroscopy of their member stars using the ESO Very Large Telescope. In
this paper we add metallicities and radial velocities for a new sample of 28 globular clusters, including in particular globular clusters in the MW halo and the Galactic bulge. Together with our previous results, this study brings the number of globular clusters with homogeneous measurements to ∼69% of those listed in the Harris’ catalogue. As in our previous work, we have used the Ca ii triplet lines to derive metallicities and radial velocities. For most of the clusters in this study, this is the first analysis based on spectroscopy of individual member stars. The metallicities derived from the Ca ii triplet are then compared to the results of our parallel study based
on spectral fitting in the optical region and the implications for different calibrations of the Ca ii triplet line strengths are discussed. We also comment on some interesting clusters and investigate the presence of an abundance spread in the globular clusters here. A hint of a possible intrinsic spread is found for NGC 6256, which therefore appears to be a good candidate for further study.SV and MZ acknowledge support by the Ministry of
Economy, Development, and Tourism’s Millennium Science Initiative through
grant IC120009, awarded to The Millennium Institute of Astrophysics (MAS),
by Fondecyt Regular 1150345 and by the BASAL-CATA Center for Astrophysics and Associated Technologies PFB-06. SV also acknowledges support
by the ESO studentship programme 2012–2014
FORS2/VLT survey of Milky Way globular clusters I. Description of the method for derivation of metal abundances in the optical and application to NGC 6528, NGC 6553, M 71, NGC 6558, NGC 6426, and Terzan 8
Context. We have observed almost one third of the globular clusters in the Milky Way, targeting distant and/or highly reddened objects, as well as a few reference clusters. A large sample of red giant stars was observed with FORS2 at VLT/ESO at R ~ 2000. The method for deriving stellar parameters is presented with application to six reference clusters.Aims. We aim at deriving the stellar parameters effective temperature, gravity, metallicity, and alpha-element enhancement as well as the radial velocity to confirm the membership of individual stars in each cluster. We analyse the spectra collected for the reference globular clusters NGC 6528 ([Fe/H] ~-0.1), NGC 6553 ([Fe/H] ~-0.2), M 71 ([Fe/H] ~-0.8), NGC 6558 ([Fe/H] ~-1.0), NGC 6426 ([Fe/H] ~-2.1), and Terzan 8 ([Fe/H] ~-2.2). They cover the full range of globular cluster metallicities, and are located in the bulge, disc, and halo.Methods. Full spectrum-fitting techniques were applied by comparing each target spectrum with a stellar library in the optical region at 4560-5860 Å. We employed the library of observed spectra MILES, and the Coelho synthetic library. We validated the method by recovering the known atmospheric parameters for 49 well-studied stars that cover a wide range in the parameter space. We adopted as final stellar parameters (effective temperatures, gravities, metallicities) the average of results using the observed and synthetic spectral libraries.Results. We identified 4 member stars in NGC 6528, 13 in NGC 6553, 10 in M 71, 5 in NGC 6558, 5 in NGC 6426, and 12 in Terzan 8. Radial velocities, Teff, log(g), [Fe/H], and alpha-element enhancements were derived. We derived 〈vhelio〉 = -242 ± 11 km s-1, [Fe/H] = - 2.39 ± 0.04, [Mg/Fe] = 0.38 ± 0.06 for NGC 6426 from spectroscopy for the first time.Conclusions. The method proved to be reliable for red giant stars observed with resolution R ~ 2000, yielding results compatible with high-resolution spectroscopy. The derived α-element abundances show [α/Fe] vs. [Fe/H] consistent with that of field stars at the same metallicities
Development of a highly sensitive real-time PCR system for the quantification of soybean as a potential allergenic ingredient
Soybean is a food ingredient with both techno- and biofunctionality properties, whose use has
been increasing considerably in the past decades [I]. Besides its numerous applications, soybean
is widely used by the food industry in processed foodstuffs such as sausages, hamburgers or
hams. However, since soybean is considered one of the most common foods known to cause
allergic reactions in sensitized individuais, the European Union established legislation aiming to
protect these patients According to the Directive 2007/68/EC, soybean plus 13 other groups of
foods must always be labeled independently of its amount For labeling compliance monitoring,
the development ofadequate methodology for soybean detection is ofutmost importance
In this work, we propose developing a molecular approach based on real-time polymerase chain
reaction (PCR) system with adequate sensitivity for the quantitative analysis of soy as a
potential aliergen in meat products. For this purpose, different model samples of pork meat
spiked with known amounts of isolated or concentrated soy protein, ranging from 10% to
O 00 I %, with and without heat treatment were prepared. The reference mixtures were used to
develop a calibration model based on real-time PCR using primers and hydrolysis probes
specifically designed to target eukaryotic reference (universal) and lectin (specific for soybean)
genes
Numerical investigation of an innovative furnace concept for industrial coil coating lines
This research was funded by the European Community's Framework Programme for Research and Innovation Horizon 2020 under grant agreement no. 768692 (ECCO).
Publisher Copyright:
© 2023 The Author(s)In this work, the engineering performance of an innovative furnace concept developed for continuous drying and curing of paint-coated metal sheets (coil coating process) is investigated through advanced modeling and numerical simulation techniques. Unlike the traditional and wide-spread coil coating furnaces – which operate according to the so-called convective air-drying technology –, the present furnace concept relies on infrared radiative heating to drive solvent evaporation and curing reactions. Radiative heat is provided by the operation of radiant porous burners which are fed with evaporated solvents. The current furnace concept consists of two main chambers (the radiant burner section and the curing oven section) with different gas compositions (atmospheres) that are separated by a semi-transparent window. The window allows energy transfer and prevents gas mixing between the two sections. To utilize the solvent-loaded atmosphere available in the curing oven section as fuel – and to prevent the development of explosive conditions therein –, a novel inertization concept shielding the curing oven section from the external environment is considered. The current furnace concept aims at improving process intensification and promoting energy efficiency. For the current furnace concept, numerical simulation results support a suitable and competitive performance for drying the applied coatings in comparison with the traditional approach. Simultaneously, a safe operation is predicted, without (i) solvent leakage from the furnace and (ii) oxygen entrainment from the surrounding ambient into the furnace. These conditions are satisfied demonstrating a safe operation and a complete evaporation of solvents from applied liquid film coatings.publishersversionpublishe
Numerical investigation of an innovative furnace concept for industrial coil coating lines
In this work, the engineering performance of an innovative furnace concept developed for continuous drying and curing of paint-coated metal sheets (coil coating process) is investigated through advanced modeling and numerical simulation techniques. Unlike the traditional and wide-spread coil coating furnaces – which operate according to the so-called convective air-drying technology –, the present furnace concept relies on infrared radiative heating to drive solvent evaporation and curing reactions. Radiative heat is provided by the operation of radiant porous burners which are fed with evaporated solvents. The current furnace concept consists of two main chambers (the radiant burner section and the curing oven section) with different gas compositions (atmospheres) that are separated by a semi-transparent window. The window allows energy transfer and prevents gas mixing between the two sections. To utilize the solvent-loaded atmosphere available in the curing oven section as fuel – and to prevent the development of explosive conditions therein –, a novel inertization concept shielding the curing oven section from the external environment is considered. The current furnace concept aims at improving process intensification and promoting energy efficiency. For the current furnace concept, numerical simulation results support a suitable and competitive performance for drying the applied coatings in comparison with the traditional approach. Simultaneously, a safe operation is predicted, without (i) solvent leakage from the furnace and (ii) oxygen entrainment from the surrounding ambient into the furnace. These conditions are satisfied demonstrating a safe operation and a complete evaporation of solvents from applied liquid film coatings
Renal denervation in an animal model of diabetes and hypertension: Impact on the autonomic nervous system and nephropathy
<p>Abstract</p> <p>Background</p> <p>The effects of renal denervation on cardiovascular reflexes and markers of nephropathy in diabetic-hypertensive rats have not yet been explored.</p> <p>Methods</p> <p>Aim: To evaluate the effects of renal denervation on nephropathy development mechanisms (blood pressure, cardiovascular autonomic changes, renal GLUT2) in diabetic-hypertensive rats. Forty-one male spontaneously hypertensive rats (SHR) ~250 g were injected with STZ or not; 30 days later, surgical renal denervation (RD) or sham procedure was performed; 15 days later, glycemia and albuminuria (ELISA) were evaluated. Catheters were implanted into the femoral artery to evaluate arterial pressure (AP) and heart rate variability (spectral analysis) one day later in conscious animals. Animals were killed, kidneys removed, and cortical renal GLUT2 quantified (Western blotting).</p> <p>Results</p> <p>Higher glycemia (p < 0.05) and lower mean AP were observed in diabetics <it>vs. </it>nondiabetics (p < 0.05). Heart rate was higher in renal-denervated hypertensive and lower in diabetic-hypertensive rats (384.8 ± 37, 431.3 ± 36, 316.2 ± 5, 363.8 ± 12 bpm in SHR, RD-SHR, STZ-SHR and RD-STZ-SHR, respectively). Heart rate variability was higher in renal-denervated diabetic-hypertensive rats (55.75 ± 25.21, 73.40 ± 53.30, 148.4 ± 93 in RD-SHR, STZ-SHR- and RD-STZ-SHR, respectively, p < 0.05), as well as the LF component of AP variability (1.62 ± 0.9, 2.12 ± 0.9, 7.38 ± 6.5 in RD-SHR, STZ-SHR and RD-STZ-SHR, respectively, p < 0.05). GLUT2 renal content was higher in all groups <it>vs</it>. SHR.</p> <p>Conclusions</p> <p>Renal denervation in diabetic-hypertensive rats improved previously reduced heart rate variability. The GLUT2 equally overexpressed by diabetes and renal denervation may represent a maximal derangement effect of each condition.</p
Physicochemical characterization of dried vs. freeze-dried marine macroalgae waste aiming further recovery
Plastin and spectrin cooperate to stabilize the actomyosin cortex during cytokinesis
Cytokinesis, the process that partitions the mother cell into two daughter cells, requires the assembly and constriction of an equatorial actomyosin network. Different types of non-motor F-actin crosslinkers localize to the network, but their functional contribution remains poorly understood. Here, we describe a synergy between the small rigid crosslinker plastin and the large flexible crosslinker spectrin in the C. elegans one-cell embryo. In contrast to single inhibitions, co-inhibition of plastin and the βH-spectrin (SMA-1) results in cytokinesis failure due to progressive disorganization and eventual collapse of the equatorial actomyosin network. Cortical localization dynamics of non-muscle myosin II in co-inhibited embryos mimic those observed after drug-induced F-actin depolymerization, suggesting that the combined action of plastin and spectrin stabilizes F-actin in the contractile ring. An in silico model predicts that spectrin is more efficient than plastin at stabilizing the ring and that ring formation is relatively insensitive to βH-spectrin length, which is confirmed in vivo with a sma-1 mutant that lacks 11 of its 29 spectrin repeats. Our findings provide the first evidence that spectrin contributes to cytokinesis and highlight the importance of crosslinker interplay for actomyosin network integrity
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