El efecto del cloruro de N-cetilpiridina sobre la absorción de un colorante reactivo sobre Leacril. Potencial zeta y termodinámica de absorción.

Se ha efectuado una investigación de tipo experimental sobre la absorción y potencial de flujo de Remazol Blue R (RBB-R) con fibras Leacril tratadas y sin tratar con 10^-3 M de cloruro de N-cetilpiridina (N-CP-CI). Los modelos de haces decapilares utilizados son los de Goring y Mason, Biefer y Mason, y Chang y Roberston. El comportamiento cualitativo del potencial zeta es similar en los tres modelos usados. El aumento observado del potencial zeta, en Leacril sin tratar, entre 10^-6 M y 10^-5 de RBB-R en solución se debe probablemente a las atracciones hidrofóbicas entre la fibra y la parte hidrofóbica del colorante. A concentraciones mayores a ca. 10^-5 de colorante, las reacciones químicas entre los grupos -NH2, y NH del colorante y el sulfato y los grupos de terminales de sulfato del Leacril podrían probablemente ser la causa de la disminución observada del potencial zeta en la gama de concentración mencionada. La cantidad de RBB-R absorbida en el Leacril sin tratar se ve favorecida por el aumento de la temperatura de adsorción. Se debe ello a los enlaces químicos implícitos en el proceso de absorción. Los valores del potencial zeta negativos, en fibra tratada, son más elevados que los valores del potencial zeta para fibras sin tratar en toda la gama de concentración ensayada en RBB-R. Este hecho viene a demostrar un aumento de la fortaleza de las interacciones entre la fibra de Leacril tratada y RBB-R. También se presentan datos sobre la cinética y termodinámica de absorción de Remazol Brillant Blue R, en fibras Leacril tratadas y sin tratar a diferentes temperaturas, habiéndose obtenido los valores de las constantes de velocidad de la reacción tiempo de media tintura y coeficientes de difusión del colorante en los mencionados procesos de absorción. De forma similar, se han obtenido los cambios de entalpia y entropía en relación con el proceso de tintura del Leacril. Los resultados ponen de manifiesto la presencia de fuertes enlaces químicos entre los sistemas, tratados y no tratados, de Leacril/Remazol Brilliant Blue.An experimental investigation on the streaming potential and sorption of Remazol Brilliant Blue R (RBB-R) on both wtreated and treated Leacril fibres with 10^-3 M of N-cetylpyridinium chloride (N-CP-CI) has been carried out. The models of bundle of capillaries employed in the determination of zeta potential of Leacril are the models of Goring and Mason, Biefer and Mason and Chang and Robertson. The qualitative behaviour of zeta potential is similar in the three models employed. The increasing of zeta potential observed, by untreated Leacril, between and 10^-5 M and ca. 10^-5 M of RBB-R in solution is probably due to the hydrophobic attractions between the fibre and the hydrophobic part of the dye. At concentrations higher than ca 10^-5 of dye, the chemical reactions between both -NH2, and the -NH groups of the dye and the sulphonate and sulfate end-groups of the Leacril, respectively, could possibly cause the observed decreasing in the zeta potential, at the mentioned concentration range. The amount of RBB-R absorbed on untreated Leacril is favoured by the increasing in adsorption temperature. This fact is due to the chemical bonds involved in the absorption process. The values of the negative zeta potential, by treated fibre, are higher than of zeta potential by untreated fibres in all the concentration range tested of RBB-R. This fact shows an increasing in the strength of the interactions between the treated Leacril fibre and the RBB-R. Data of the kinetics and thermodynamics of absorption of Remazol Brilliant Blue R on both untreated and treated Leacril at different temperatures are presented, obtaining both the values for the rate constant of the reaction, the half-dyeing time and the diffusion coefficients of the dye in the above processes of absorption. They have also been obtained the changes of enthalpy and entropy related to the process of dyeing of Leacril. Results reveal the presence of strong chemical bonds between both the untreated and treated Leacril/Remazol Brilliant Blue systems.Nous avons entrepis des recherches de type expérimentel sur l'absorption et le potentiel de flux de Remazol Blue R (RBB-R) avec des fibres Leacril traitées et non traitées avec 10^-3 M de chlorure de N-cétylpyridine (N-CP-CI). Les modèles de faisceaux capillaires utilisés sont ceux de Goring et Mason, Biefer et Mason, et Chang et Roberston. Le comportement qualitatif du potential zêta est similaire dans les trois modèles utilisés. L'augmentation observé du potentiel zêta, sur du Leacril non traité, entre 10^-6 M et 10^-5 de RBB-R en solution, est probablement dû aux attractions hydrophobiques entre la fibre et la partie hydrophobique du colorant. À des concentrations de colorant supérieures a 10^-5 ca, les reactions chimiques entre les groupes -NH, et NH du colorant et le sulfonate et les groupes terminaux de sulfate du Leacril pourraient probablement expliquer la diminution observée du potentiel zêta dans la gamme de concentration mentionnée. La quantité de RBB-R absorbée dans le leacril non traité est favorisée par l'augmentation de la température d'adsorption. Cela est dû aux liaisons chimiques implicites dans le processus d'absorption. Les valeurs négatives du potentiel zêta, pour la fibre traitée, sont supérieures aux valeurs du potentiel zêta pour des fibres non traitées dans toute la gamme de concentration testée en RBB-R. Ce fait démontre l'augmentation de la robustesse des interactions entre la fibre de Leacril traitée et RBB-R. Nous apportons aussi des données sur la cinétique et la thermodynamique d'absorption de Ramazol Brillant Blue R, sur des fibres Leacril traitées et non traitées, à différentes températures, puisque nous avons obtenu les valeurs des constantes de vitesse de la réaction temps de demi-teinture et des coefficients de diffusion du colorant dans les processus d'absorption cités. De même, nous avons obtenu les changements d'enthalpie et d'entropie par rapport au processus de teinture du Leacril. Les résultats mettent en évidence la présence de fortes liaisons chimiques entre les systèmes, traités et non traités, de Leacril/Remazol Brillant Blue.Peer Reviewe

El tapial de las murallas de Granada

Español: En este trabajo se establecen las características del material empleado en las construcciones de los distintos recintos amurallados de la ciudad de Granada, que se conocen históricamente como "Alcazabas de Granada" y arrabales, distinguiendo entre material de interior de muro y revestimientos. Como objetivo final, este estudio nos ha permitido establecer conclusiones más precisas sobre la metodología constructiva utilizada en estos recintos amurallados, y la evolución de ésta a lo largo de las distintas épocas. Inglés: This paper deals with a general analysis of the materials used in the city walls, commonly known as Alcazabas, of Granada. The study concentrates in the material of the inner walls as well as the exterior. This has allowed for a deeper insight in the construction methods used for city walls during different ages

The Physical Conditions in Starbursts Derived from Bayesian Fitting of Mid-IR SEDS: 30 Doradus as a Template

To understand and interpret the observed Spectral Energy Distributions (SEDs) of starbursts, theoretical or semi-empirical SED models are necessary. Yet, while they are well-founded in theory, independent verification and calibration of these models, including the exploration of possible degeneracies between their parameters, are rarely made. As a consequence, a robust fitting method that leads to unique and reproducible results has been lacking. Here we introduce a novel approach based on Bayesian analysis to fit the Spitzer-IRS spectra of starbursts using the SED models proposed by Groves et al. (2008). We demonstrate its capabilities and verify the agreement between the derived best fit parameters and actual physical conditions by modelling the nearby, well-studied, giant HII region 30 Dor in the LMC. The derived physical parameters, such as cluster mass, cluster age, ISM pressure and covering fraction of photodissociation regions, are representative of the 30 Dor region. The inclusion of the emission lines in the modelling is crucial to break degeneracies. We investigate the limitations and uncertainties by modelling sub-regions, which are dominated by single components, within 30 Dor. A remarkable result for 30 Doradus in particular is a considerable contribution to its mid-infrared spectrum from hot ({\simeq} 300K) dust. The demonstrated success of our approach will allow us to derive the physical conditions in more distant, spatially unresolved starbursts.Comment: 17 pages, 10 figures. Accepted por publication in the Astrophysical Journa

On the relationship of shock waves to flares and coronal mass ejections

Context: Metric type II bursts are the most direct diagnostic of shock waves in the solar corona. Aims: There are two main competing views about the origin of coronal shocks: that they originate in either blast waves ignited by the pressure pulse of a flare or piston-driven shocks due to coronal mass ejections (CMEs). We studied three well-observed type II bursts in an attempt to place tighter constraints on their origins. Methods: The type II bursts were observed by the ARTEMIS radio spectrograph and imaged by the Nan\c{c}ay Radioheliograph (NRH) at least at two frequencies. To take advantage of projection effects, we selected events that occurred away from disk center. Results: In all events, both flares and CMEs were observed. In the first event, the speed of the shock was about 4200 km/s, while the speed of the CME was about 850 km/s. This discrepancy ruled out the CME as the primary shock driver. The CME may have played a role in the ignition of another shock that occurred just after the high speed one. A CME driver was excluded from the second event as well because the CMEs that appeared in the coronagraph data were not synchronized with the type II burst. In the third event, the kinematics of the CME which was determined by combining EUV and white light data was broadly consistent with the kinematics of the type II burst, and, therefore, the shock was probably CME-driven. Conclusions: Our study demonstrates the diversity of conditions that may lead to the generation of coronal shocks.Comment: 13 pages, 14 figures. "Astronomy and Astrophysics", in pres

Feedback and feeding in the context of galaxy evolution with SPICA: direct characterization of molecular outflows and inflows

A far-infrared observatory such as the {\it SPace Infrared telescope for Cosmology and Astrophysics} ({\it SPICA}), with its unprecedented spectroscopic sensitivity, would unveil the role of feedback in galaxy evolution during the last $\sim10$ Gyr of the Universe ($z=1.5-2$), through the use of far- and mid-infrared molecular and ionic fine structure lines that trace outflowing and infalling gas. Outflowing gas is identified in the far-infrared through P-Cygni line shapes and absorption blueshifted wings in molecular lines with high dipolar moments, and through emission line wings of fine-structure lines of ionized gas. We quantify the detectability of galaxy-scale massive molecular and ionized outflows as a function of redshift in AGN-dominated, starburst-dominated, and main-sequence galaxies, explore the detectability of metal-rich inflows in the local Universe, and describe the most significant synergies with other current and future observatories that will measure feedback in galaxies via complementary tracers at other wavelengths.Comment: This paper belongs to the SPICA Special Issue on PASA. Accepted for publication in PAS

The Massive Star Clusters in the Dwarf Merger ESO 185-IG13: is the Red Excess Ubiquitous in Starbursts?

We have investigated the starburst properties of the luminous blue compact galaxy ESO 185-IG13. The galaxy has been imaged with the high resolution cameras onboard to the Hubble Space Telescope. From the UV to the IR, the data reveal a system shaped by hundreds of young star clusters, and fine structures, like a tidal stream and a shell. The presence of numerous clusters and the perturbed morphology indicate that the galaxy has been involved in a recent merger event. Using previous simulations of shell formation in galaxy mergers we constrain potential progenitors of ESO 185-IG13. The analysis of the star cluster population is used to investigate the properties of the present starburst and to date the final merger event, which has produced hundreds of clusters younger than 100 Myr. We have found a peak of cluster formation only 3.5 Myr old. A large fraction of these clusters will not survive after 10-20 Myr, due to the "infant mortality" caused by gas expulsion. However, this sample of clusters represents an unique chance to investigate the youngest phases of cluster evolution. As already observed in the analog blue compact galaxy Haro 11, a fraction of young clusters are affected by a flux excess at wavelengths longer than 8000 \AA. Ages, masses, and extinctions of clusters with this NIR excess are estimated from UV and optical data. We discuss similarities and differences of the observed NIR excess in ESO 185-IG13 clusters with other cases in the literature. The cluster ages and masses are used to distinguish among the potential causes of the excess. We observe, as in Haro 11, that the use of the IR and the (commonly used) I band data results in overestimates of age and mass in clusters affected by the NIR excess. This has important implications for a number of related studies of star clusters.Comment: 23 pages, 16 figures, accepted for publication in MNRA

Unbiased large spectroscopic surveys of galaxies selected by SPICA using dust bands

The mid-infrared (IR) range contains many spectral features associated with large molecules and dust grains such as polycyclic aromatic hydrocarbons (PAHs) and silicates. These are usually very strong compared to fine-structure gas lines, and thus valuable in studying the spectral properties of faint distant galaxies. In this paper, we evaluate the capability of low-resolution mid-IR spectroscopic surveys of galaxies that could be performed by SPICA. The surveys are designed to address the question how star formation and black hole accretion activities evolved over cosmic time through spectral diagnostics of the physical conditions of the interstellar/circumnuclear media in galaxies. On the basis of results obtained with Herschel far-IR photometric surveys of distant galaxies and Spitzer and AKARI near- to mid-IR spectroscopic observations of nearby galaxies, we estimate the numbers of the galaxies at redshift z > 0.5, which are expected to be detected in the PAH features or dust continuum by a wide (10 deg^2) or deep (1 deg^2) blind survey, both for a given observation time of 600 hours. As by-products of the wide blind survey, we also expect to detect debris disks, through the mid-IR excess above the photospheric emission of nearby main-sequence stars, and we estimate their number. We demonstrate that the SPICA mid-IR surveys will efficiently provide us with unprecedentedly large spectral samples, which can be studied further in the far-IR with SPICA.Comment: Paper accepted for publication on PASA on 18th October 2017, as part of the SPICA Special Issu

How Many CMEs Have Flux Ropes? Deciphering the Signatures of Shocks, Flux Ropes, and Prominences in Coronagraph Observations of CMEs

We intend to provide a comprehensive answer to the question on whether all Coronal Mass Ejections (CMEs) have flux rope structure. To achieve this, we present a synthesis of the LASCO CME observations over the last sixteen years, assisted by 3D MHD simulations of the breakout model, EUV and coronagraphic observations from STEREO and SDO, and statistics from a revised LASCO CME database. We argue that the bright loop often seen as the CME leading edge is the result of pileup at the boundary of the erupting flux rope irrespective of whether a cavity or, more generally, a 3-part CME can be identified. Based on our previous work on white light shock detection and supported by the MHD simulations, we identify a new type of morphology, the `two-front' morphology. It consists of a faint front followed by diffuse emission and the bright loop-like CME leading edge. We show that the faint front is caused by density compression at a wave (or possibly shock) front driven by the CME. We also present high-detailed multi-wavelength EUV observations that clarify the relative positioning of the prominence at the bottom of a coronal cavity with clear flux rope structure. Finally, we visually check the full LASCO CME database for flux rope structures. In the process, we classify the events into two clear flux rope classes (`3-part', `Loop'), jets and outflows (no clear structure). We find that at least 40% of the observed CMEs have clear flux rope structures. We propose a new definition for flux rope CMEs (FR-CMEs) as a coherent magnetic, twist-carrying coronal structure with angular width of at least 40 deg and able to reach beyond 10 Rsun which erupts on a time scale of a few minutes to several hours. We conclude that flux ropes are a common occurrence in CMEs and pose a challenge for future studies to identify CMEs that are clearly not FR-CMEs.Comment: 26 pages, 9 figs, to be published in Solar Physics Topical Issue "Flux Rope Structure of CMEs