8 resultados para Bubble

em Universidad de Alicante


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The catalytic activity and durability of 2 wt.% Pd/Al2O3 in powder and washcoated on cordierite monoliths were examined for the liquid phase hydrodechlorination (LPHDC) of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/Fs), also known as dioxins. NaOH was employed as a neutralizing agent, and 2-propanol was used as a hydrogen donor and a solvent. Fresh and spent powder and monolith samples were characterized by elemental analysis, surface area, hydrogen chemisorption, scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX), and transmission electron microscopy/energy dispersive X-ray spectroscopy (TEM/EDX). Three reactor configurations were compared including the slurry and monolith batch reactors as well as the bubble loop column resulting in 100, 70, and 72% sample toxicity reduction, respectively, after 5 h of reaction. However, the slurry and monolith batch reactors lead to catalyst sample loss via a filtration process (slurry) and washcoat erosion (monolith batch), as well as rapid deactivation of the powder catalyst samples. The monolith employed in the bubble loop column remained stable and active after four reaction runs. Three preemptive regeneration methods were evaluated on spent monolith catalyst including 2-propanol washing, oxidation/reduction, and reduction. All three procedures reactivated the spent catalyst samples, but the combustion methods proved to be more efficient at eliminating the more stable poisons.

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Context. The discovery of several clusters of red supergiants towards l = 24°−30° has triggered interest in this area of the Galactic plane, where lines of sight are very complex and previous explorations of the stellar content were very preliminary. Aims. We attempt to characterise the stellar population associated with the H ii region RCW 173 (=Sh2-60), located at, as previous studies have suggested that this population could be beyond the Sagittarius arm. Methods. We obtained UBV photometry of a stellar field to the south of the brightest part of RCW 173, as well as spectroscopy of about twenty stars in the area. We combined our new data with archival 2MASS near-infrared photometry and Spitzer/GLIMPSE imaging and photometry, to achieve a more accurate characterisation of the stellar sources and the associated cloud. Results. We find a significant population of early-type stars located at d = 3.0 kpc, in good agreement with the “near” dynamical distance to the H ii region. This population should be located at the near intersection of the Scutum-Crux arm. A luminous O7 II star is likely to be the main source of ionisation. Many stars are concentrated around the bright nebulosity, where GLIMPSE images in the mid infrared show the presence of a bubble of excited material surrounding a cavity that coincides spatially with a number of B0-1 V stars. We interpret this as an emerging cluster, perhaps triggered by the nearby O7 II star. We also find a number of B-type giants. Some of them are located at approximately the same distance, and may be part of an older population in the same area, characterised by much lower reddening. A few have shorter distance moduli and are likely to be located in the Sagittarius arm. Conclusions. The line of sight in this direction is very complex. Optically visible tracers delineate two spiral arms, but seem to be absent beyond d ≈ 3 kpc. Several H ii regions in this area suggest that the Scutum-Crux arm contains thick clouds actively forming stars. All these populations are projected on top of the major stellar complex signposted by the clusters of red supergiants.

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La actual crisis económica ha tenido impacto en prácticamente todos los sectores socioeconómicos, entre los que se incluye la educación como uno de los grandes perjudicados. En este momento de incertidumbre sobre la viabilidad de la educación tradicional y la supuesta burbuja en la enseñanza (agravada por las tasas de paro juvenil), surgen los MOOC como respuesta a la necesidad de acercamiento entre la formación y la sociedad del conocimiento. Pero que los cursos masivos y abiertos marquen el futuro de la educación dependerá en gran medida de su viabilidad económica. Aunque aun no se haya encontrado un modelo de negocio definitivo, las plataformas de MOOC experimentan con diferentes alternativas que, unidas a la escalabilidad de los proyectos, es previsible que generen grandes resultados.

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Purpose: To compare outcomes of big-bubble deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) for macular corneal dystrophy. Design: Prospective, randomized, interventional case series. Methods: Setting: Single hospital. Patients: Eighty-two eyes of 54 patients requiring keratoplasty for the treatment of macular corneal dystrophy without endothelial involvement were included. Main outcome measures: Operative complications, uncorrected visual acuity, best-corrected visual acuity, contrast sensitivity function, higher-order aberrations, and endothelial cell density were evaluated. Results: The DALK and PK group consisted of 35 and 41 eyes, respectively. Best-corrected visual acuity after surgery was 20/40 or better 68.5% and 70.7% of the eyes in the DALK and PK groups, respectively (P > .05). No statistically significant differences between groups were found in contrast sensitivity function with and without glare for any spatial frequency (P > .05). Significantly higher levels of higher-order aberrations were found in the DALK group (P < .01). In both groups, a progressive and statistically significant reduction in endothelial cell density was found (P < .01). At the last follow-up, the mean endothelial cell loss was 18.1% and 26.9% in DALK and PK groups, respectively (P = .03). Graft rejection episodes were seen in 5 eyes (12.1%) in the PK group, and regrafting was necessary in 3 eyes (7.3%). Recurrence of the disease was documented in 5.7% and 4.8% of the eyes in the DALK and PK groups, respectively. Conclusions: Deep anterior lamellar keratoplasty with the big-bubble technique provided comparable visual and optical results as PK and resulted in less endothelial damage, as well as eliminating endothelial rejection in macular corneal dystrophy. Deep anterior lamellar keratoplasty surgery is a viable option for macular corneal dystrophy without endothelial involvement.

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The decomposition of azodicarbonamide, used as foaming agent in PVC—plasticizer (1/1) plastisols was studied by DSC. Nineteen different plasticizers, all belonging to the ester family, two being polymeric (polyadipates), were compared. The temperature of maximum decomposition rate (in anisothermal regime at 5 K min−1 scanning rate), ranges between 434 and 452 K. The heat of decomposition ranges between 8.7 and 12.5 J g−1. Some trends of variation of these parameters appear significant and are discussed in terms of solvent (matrix) and viscosity effects on the decomposition reactions. The shear modulus at 1 Hz frequency was determined at the temperature of maximum rate of foaming agent decomposition, and differs significantly from a sample to another. The foam density was determined at ambient temperature and the volume fraction of bubbles was used as criterion to judge the efficiency of the foaming process. The results reveal the existence of an optimal shear modulus of the order of 2 kPa that corresponds roughly to plasticizer molar masses of the order of 450 ± 50 g mol−1. Heavier plasticizers, especially polymeric ones are too difficult to deform. Lighter plasticizers such as diethyl phthalate (DEP) deform too easily and presumably facilitate bubble collapse.

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Introducing teaching about healthy solutions in buildings and BIM has been a challenge for the University of Alicante. Teaching attached to very tighten study plans conditioned the types of methods that could be used in the past. The worldwide situation of crisis that especially reached Spain and the bursting of the housing bubble generated a lack of employment that reached universities where careers related to construction, Architecture and Architectural Technologist, suffered a huge reduction in the number of students enrolled. In the case of the University of Alicante, students’ enrolment for Architectural Technology reached an 80% reduction. The necessity of a reaction against this situation made the teachers be innovative and use the new Bologna adapted study plans to develop new teaching experiences introducing new concepts: people wellbeing in buildings and BIM. Working with healthy solutions in buildings provided new approaches for building design and construction as an alternative to sustainability. For many years sustainability was the concept that applied to housing gave buildings an added value and the possibility of having viability in a very complex scenario. But after lots of experiences, the approved methodologies for obtaining sustainable housing were ambiguous and at the end, investors, designers, constructors and purchasers cannot find real and validated criteria for obtaining an effective sustainable house. It was the moment to work with new ideas and concepts and start facing buildings from the users’ point of view. At the same time the development of new tools, BIM, has opened a wide range of opportunities, innovative and suggestive, that allows simulation and evaluation of many building factors. This paper describes the research in teaching developed by the University of Alicante to adapt the current study plans, introducing work with healthy solutions in buildings and the use of BIM, with the aim of attracting students by improving their future employability. Pilot experiences have been carried out in different subjects based on the work with projects and case studies under an international frame with the cooperation of different European partner universities. The use of BIM tools, introduced in 2014, solved the problems that appeared in some subjects, mainly building construction, and helped with the evaluation of some healthy concepts that presented difficulties until this moment as knowledge acquired by the students was hard to be evaluated. The introduction of BIM tools: Vasari, FormIt, Revit and Light Control among others, allowed the study of precise healthy concepts and provided the students a real understand of how these different parameters can condition a healthy architectural space. The analysis of the results showed a clear acceptance by the students and gave teachers the possibility of opening new research lines. At the same time, working with BIM tools to obtain healthy solutions in building has been a good option to improve students’ employability as building market in Spain is increasing the number of specialists in BIM with a wider knowledge.

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Tras la aprobación del Real Decreto Legislativo 2/2008 –Ley del Suelo–, nos encontramos ante un modelo territorial y un modelo de desarrollo, que acaba con el arcaico patrón de ciudad dispersa, encontrándose, no obstante, ante las gravísimas consecuencias espaciales generadas por la denominada “burbuja inmobiliaria”, unida a una crisis de consecuencias insospechadas, en el ámbito de la denominada globalización económica, de la que nuestro país no ha logrado sustraerse con Leyes vacías de instrumentos económicos que se han transferido a las Comunidades Autónomas, nos hallamos ante una oportunidad perdida fruto de una no siempre bien calculada descentralización. De este modo, en el presente artículo nos aproximamos a la importancia que muestran los denominados “instrumentos económicos” en la normativa que recoge los pormenores relacionados con el “suelo”, en España, en la primera de nuestras Leyes, la de 1956, en la de 2008 y en el recién aprobado Texto Refundido de la Ley del Suelo y Rehabilitación Urbana –Real Decreto Legislativo 7/2015–, en el ámbito estatal. Para ello, tras definir y valorar los enfoques conceptuales relativos al “suelo” y sus tipologías, se concretan y estudian los instrumentos económicos que se recogen en la Ley del Suelo española y su relación con las nuevas formas de “hacer ciudad”.

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Las consecuencias del último boom inmobiliario han abierto el debate alrededor del crecimiento urbano en España, especialmente en áreas con una fuerte presión turística y residencial. En este trabajo se analizan algunas de las implicaciones de la crisis financiera mundial sobre la planificación urbanística municipal, centrando el estudio en la provincia de Alicante, uno de los ámbitos que mejor ilustran el éxito y la caída del modelo inmobiliario hispano. La unidad básica de análisis la componen las figuras de planeamiento municipal y estrategias territoriales vigentes, y su traducción en suelos urbanos inconclusos. Considerando que se trata de actuaciones durmientes a la espera de un contexto económico favorable, la situación hace pensar que la burbuja inmobiliaria no estaría estallada sino tan sólo desinflada. El objetivo es reflexionar, con carácter propositivo, sobre las estrategias de gestión del territorio que emergen durante los últimos años a raíz de la crisis financiera e inmobiliaria, tratando de relanzar algunas cuestiones que deberían preocupar en la planificación urbanística y territorial de la provincia de Alicante, y por extensión, de otros espacios afectados por el crash inmobiliario.