578 research outputs found
A photoionization model of the spatial distribution of the optical and mid-IR properties in NGC595
We present a set of photoionization models that reproduce simultaneously the
observed optical and mid-infrared spatial distribution of the HII region NGC595
in the disk of M33 using the code CLOUDY. Both optical (PMAS-Integral Field
Spectroscopy) and mid-infrared (8 mi and 24 mi bands from Spitzer) data provide
enough spatial resolution to model in a novel approach the inner structure of
the HII region. We define a set of elliptical annular regions around the
central ionizing cluster with an uniformity in their observed properties and
consider each annulus as an independent thin shell structure. For the first
time our models fit the relative surface brightness profiles in both the
optical (Halpha, [OII], [OIII]) and the mid-infrared emissions (8 mi and 24
mi), under the assumption of a uniform metallicity (12+log(O/H) = 8.45; Esteban
et al. 2009) and an age for the stellar cluster of 4.5 Myr (Malumuth et al.
1996). Our models also reproduce the observed uniformity of the R23 parameter
and the increase of the [OII]/[OIII] ratio due to the decrease of the
ionization parameter. The variation of the Halpha profile is explained in terms
of the differences of the occupied volume (the product of filling factor and
total volume of the shell) in a matter-bounded geometry, which also allows to
reproduce the observed pattern of the extinction. The 8 mi/24 mi ratio is low
(ranging between 0.04 and 0.4) because it is dominated by the surviving of
small dust grains in the HII region, while the PAHs emit more weakly because
they cannot be formed in these thin HII gas shells. The ratio is also well
fitted in our models by assuming a dust-to-gas ratio in each annulus compatible
with the integrated estimate for the whole HII region after the 70 mi, and 160
mi Spitzer observations.Comment: Accepted for publication in MNRAS, 9 pages, 17 figure
Synthesis, structure, properties and biological behaviour of the complex [RuIV (H2L) CI2] 2H2O (H4L- 1,2-cyclohexanediamminetetraacetic acid)
The highly water-soluble ruthenium complex [Ru(H2L)Cl 2]·2H2O, in which H4L is the sequestering ligand trans-l,2-cyclohexanediamminetetraacetic acid (cdta) has been synthesized, structurally characterized and its properties studied. The X-ray crystallographic study shows that the chelating coordinated ligand is tetradentate while the ruthenium environment is octahedral and slightly distorted, with two chloride anions coordinated in cis positions. Potentiometric, conductimetric and infrared studies confirm the presence of two free carboxylic groups, while electronic and voltammetric studies show that the central ion is Ru(IV). The testing of the cytotoxic activity of this complex against three different human cancer cell lines indicates that [Ru(H 2L)Cl2]·2H2O shows a remarkable and selective antiproliferative effect against the human uterine neck carcinoma HeLa and the malign adenocarcinoma ADLD, showing only a discrete turnout cell inhibition activity against colon adenocarcinoma HT-29. The important antiprotiferative behaviour of complex against the human adenocarcinoma ADLD, indicates that [Ru(H2L)Cl2]·2H2O might be considered as potential antineoplastic compound.Ministerio de Ciencias y Tecnología PPQ2000-0035-P4 BQU2001-245
Estudio comparativo de la incidencia de la Directiva Seveso por ámbitos territoriales. El caso particular de la región de Andalucía
Desde la entrada en vigor de la primera Directiva Seveso en Europa, el concepto de prevención de accidentes graves por sustancias peligrosas ha evolucionado de forma diferente dependiendo de la transposición particular de cada Estado Miembro a su propio ordenamiento jurídico. Adicionalmente, cada región con competencias en materia de seguridad industrial o protección civil ha contribuido, aún más, a la dispersión normativa existente lo que no favorece una regulación de forma universal o estándar. Uno de los aspectos normativos merecedor de una profunda actualización ante la próxima puesta en vigor de la nueva Directiva Seveso III, es aquel que incide sobre las zonas de influencia donde existen establecimientos industriales afectados por la Directiva. En el presente trabajo se va a realizar una evolución histórica de la afectación por ámbito geográfico en la década 2002-2012. El análisis territorial comienza con la distribución geográfica de laafectación en la Unión Europea. De manera similar, se vadescendiendo geográficamente hasta estudiar el estadoespañol y, finalmente, alcanzará a la región de Andalucíadonde, se profundizará aún más, hasta alcanzar el nivelterritorial de provincias y, municipios. Del análisis se deducenunas primeras conclusiones particulares relativas tanto a las concentraciones de establecimientos Seveso y de los sectores industriales más significativos cubiertos por dicha normativa
Evidence For An Unusual Kinetic Phenomenon In The Metallation Of Porphyrins
Reaction of copper(II) with water soluble porphyrins (H₂porph) in the presence of ethylenediamine shows an unusual and so far unreported kinetic phenomenon that can be explained in terms of supramolecular assembly formation apparently involving all solute species as confirmed via light scattering and conductivity measurements
Dissecting the RELICS cluster SPT-CLJ0615-5746 through the intracluster light: confirmation of the multiple merging state of the cluster formation
The intracluster light (ICL) fraction, measured at certain specific
wavelengths, has been shown to provide a good marker for determining the
dynamical stage of galaxy clusters, i.e., merging versus relaxed, for small to
intermediate redshifts. Here, we apply it for the first time to a high-redshift
system, SPT-CLJ0615-5746 at z=0.97, using its RELICS (Reionization Lensing
Cluster Survey) observations in the optical and infrared. We find the ICL
fraction signature of merging, with values ranging from 16 to 37%. A careful
re-analysis of the X-ray data available for this cluster points to the presence
of at least one current merger, and plausibly a second merger. These two
results are in contradiction with previous works based on X-ray data, which
claimed the relaxed state of SPT-CLJ0615-5746, and confirmed the evidences
presented by kinematic analyses. We also found an abnormally high ICL fraction
in the rest-frame near ultraviolet wavelengths, which may be attributed to the
combination of several phenomena such as an ICL injection during recent mergers
of stars with average early-type spectra, the reversed star formation-density
relation found at this high redshift in comparison with lower-redshift
clusters, and projection effects.Comment: 15 pages, 12 figures, submitted to A&
The Nitrogen-to-Oxygen evolution in galaxies: the role of the star formation rate
The main objective of the present work is to ckeck if the star formation
efficiency plays a relevant role in the evolution of the relative abundance
N/O. We analyze the evolution of the nitrogen-to-oxygen ratio as predicted by a
set of computed theoretical models of simulated galaxies with different total
masses which are evolved assuming different collapse time scales and different
star formation efficiencies, thus producing different star formation histories.
The stellar yield set we use for all of them (Gavil\'{a}n et al. 2005) have an
important contribution of primary nitrogen proceeding from low and intermediate
mass stars. It allows to obtain a dispersion of results in the N/O-O/H plane,
when star formation efficiencies vary, in general agreement with observations.
The model results for the N/O abundance ratio are in good agreement with most
observational data trends: the extragalactic H{\sc ii} regions is well
reproduced with present time resulting abundances and the low N/O values
estimated for high-redshift objects, as well as the higher and constant values
of N/O observed for irregular and dwarf galaxies or halo stars, can be
simultaneously obtained with our models at the same low oxygen abundances. We
conclude that differences in the star formation history of galaxies and regions
within them are a key factor to explain the data in the N/O-O/H plane.Comment: 13 pages, 10 figures, accepted in MNRA
UV-A promotes long-term carotenoid production of Dunaliella in photobioreactors with retention of cell viability
The effect of adding UV-A radiations (320-400 nm) to photosynthetically active radiation (PAR, 400-700
nm) during the growth of Dunaliella bardawil in an air-fluidized bed photobioreactor was studied to
evaluate cell growth and long-term production of carotenoids. The obtained results were compared to
those obtained from D. bardawil cultures incubated under lab standard conditions for carotenoid
production, this is to say, nitrogen starvation and absence of UV-A radiation. The addition of 26.5 μmol
photons m-2 s-1 UV-A radiation to 1150 μmol photons m-2 s-1 PAR stimulated the growth of D. bardawil
cultures grown in a full nutrient culture medium. The total carotenoid content, mostly β-carotene, was
higher than that of control cultures (UV-A non added cultures) along the exponential phase. The
concentration of β-carotene in UV-A added cultures after 450 h was found to be about two-fold that of
control cultures. From the results of this work it can be concluded that the UV-A modulated addition to
PAR could be successfully applied to long-term carotenoid production processes, whereas D. bardawil
cells accumulates carotenoids with retention of its viability. It is also shown that UV-A promotes
increases of both carotenoid production per culture volume unit and the specific carotenoid production
rate (pg.cell-1), β-carotene being the major accumulated carotenoid
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