Influencia del ángulo de la proyección de abrasivos en la limpieza de materiales pétreos detríticos en Patrimonio Arquitectónico

In this research, the influence of the angle in abrasive blasting cleaning is studied on Montjuïc sandstone with black crust. After analyzing the properties of the soiling and the material, and their possible influence on the treatment, different cleaning tests were made at four different angles, keeping the complementary parameters constant. Taking the restorer’s perspective as a starting point, and in order to fulfill the practical requirements of an intervention —time and cost reduction—, tests were evaluated with USB digital microscope, stereomicroscope with 3D visualization and measurement, and colorimeter. From the results it is established that angles close to 75° minimize surface alteration, reducing differential erosion in the binding phases of detritic materials usually caused by this treatment.En este trabajo se estudia la influencia del ángulo de la proyección de abrasivos en la limpieza de una arenisca de Montjuïc con costra negra. Tras analizar las propiedades del material, de la suciedad y su posible influencia en el tratamiento, se realizan diferentes catas de limpieza con cuatro ángulos distintos manteniendo constantes el resto de parámetros de la proyección. Partiendo de la visión del conservador-restaurador y de un carácter práctico según las necesidades reales de una intervención —reducción de tiempos y costes—, los ensayos se evalúan con microscopio digital USB, microscopio estereoscópico con visualización y medición en 3D y colorímetro. De los resultados se puede determinar que ángulos cercanos a 75° minimizan la alteración de la superficie al reducir la erosión diferencial de las fases de unión que el tratamiento normalmente provoca en los materiales detríticos

Presencia de infección y lesiones mínimas en mama y otros tejidos en ovinos afectados de Maedi-Visna

5 páginas, 2 tablas.--Trabajo presentado al: XL Congreso Nacional y el XVI Congreso Internacional de la Sociedad Española de Ovinotecnia y Caprinotecnia. (Castellón de la Plana, España, 16-18 septiembre 2015).Este trabajo ha sido subvencionado por los proyectos LE361A12-1 y LE314U14 de la Junta de Castilla y León y por una beca FPU del Ministerio de Educación.Peer Reviewe

Exchange bias in laterally oxidized Au/Co/Au nanopillars

Au/Co/Au nanopillars fabricated by colloidal lithography of continuous trilayers exhibit and enhanced coercive field and the appearance of an exchange bias field with respect to the continuous layers. This is attributed to the lateral oxidation of the Co interlayer that appears upon disc fabrication. The dependence of the exchange bias field on the Co nanodots size and on the oxidation degree is analyzed and its microscopic origin clarified by means of Monte Carlo simulations based on a model of a cylindrical dot with lateral core/shell structure.Comment: 8 pages, 4 figures. Published in Appl. Phys. Let

Experiencia en el desarrollo de una herramienta para la enseñanza de comunicaciones digitales en carreras de Informática

Este trabajo presenta una herramienta de aprendizaje asistido por banco de pruebas formada por tres elementos: plataforma hardware, arquitectura de software multicapa y herramienta gráfica (gtTAL). Para el desarrollo de la herramienta se ha optado por una arquitectura multicapa donde el nivel más alto es una interfaz gráfica que permite la interacción con la plataforma sin necesidad de tener conocimientos de programación de hardware a bajo nivel. Por tanto, los estudiantes pueden testear algoritmos fácilmente sin desarrollar un nuevo programa desde cero, reduciendo significativamente el tiempo empleado para las tareas de implementación y optimización.Peer Reviewe

An insight into transfer hydrogenation reactions catalysed by iridium(iii) bis-n-heterocyclic carbenes

A variety of [M(L)2(L')2{kC,C'-bis(NHC)}]BF4 complexes (M = Rh or Ir; L = CH3CN or wingtip group; L' = I– or CF3COO–; NHC=N-heterocyclic carbene) have been tested as pre-catalysts for the transfer hydrogenation of ketones and imines. The conversions and TOF's obtained are closely related to the nature of the ligand system and metal centre, more strongly coordinating wingtip groups yielding more active and recyclable catalysts. Theoretical calculations at the DFT level support a classic stepwise metal-hydride pathway against the concerted Meerwein–Ponndorf–Verley (MPV) mechanism. The calculated catalytic cycle involves a series of ligand rearrangements due to the high trans effect of the carbene and hydrido ligands, which are more stable when situated in mutual cis positions. The reaction profiles obtained for the complexes featuring an iodide or a trifluoroacetate in one of the apical positions agree well with the relative activity observed for both catalysts

New phase diagrams for dense carbon-oxygen mixtures and white dwarf evolution

Cool white dwarfs are reliable and independent stellar chronometers. The most common white dwarfs have carbon-oxygen dense cores. Consequently, the cooling ages of very cool white dwarfs sensitively depend on the adopted phase diagram of the carbon-oxygen binary mixture. A new phase diagram of dense carbon-oxygen mixtures appropriate for white dwarf interiors has been recently obtained using direct molecular dynamics simulations. In this paper, we explore the consequences of this phase diagram in the evolution of cool white dwarfs. To do this we employ a detailed stellar evolutionary code and accurate initial white dwarf configurations, derived from the full evolution of progenitor stars. We use two different phase diagrams, that of Horowitz et al. (2010), which presents an azeotrope, and the phase diagram of Segretain & Chabrier (1993), which is of the spindle form. We computed the evolution of 0.593 and 0.878M_sun white dwarf models during the crystallization phase, and we found that the energy released by carbon-oxygen phase separation is smaller when the new phase diagram of Horowitz et al. (2010) is used. This translates into time delays that are on average a factor about 2 smaller than those obtained when the phase diagram of Segretain & Chabrier (1993) is employed. Our results have important implications for white dwarf cosmochronology, because the cooling ages of very old white dwarfs are different for the two phase diagrams. This may have a noticeable impact on the age determinations of very old globular clusters, for which the white dwarf color-magnitude diagram provides an independent way of estimating their age.Comment: 7 pages, 7 figures, accepted for publication in Astronomy and Astrophysic

On the Excitation and Formation of Circumstellar Fullerenes

We compare and analyze the Spitzer mid-infrared spectrum of three fullerene-rich planetary nebulae in the Milky Way and the Magellanic Clouds; Tc1, SMP SMC16, and SMP LMC56. The three planetary nebulae share many spectroscopic similarities. The strongest circumstellar emission bands correspond to the infrared active vibrational modes of the fullerene species C60 and little or no emission is present from Polycyclic Aromatic Hydrocarbons (PAHs). The strength of the fullerene bands in the three planetary nebulae is very similar, while the ratio of the [NeIII]15.5um/[NeII]12.8um fine structure lines, an indicator of the strength of the radiation field, is markedly different. This raises questions about their excitation mechanism and we compare the fullerene emission to fluorescent and thermal models. In addition, the spectra show other interesting and common features, most notably in the 6-9um region, where a broad plateau with substructure dominates the emission. These features have previously been associated with mixtures of aromatic/aliphatic hydrocarbon solids. We hypothesize on the origin of this band, which is likely related to the fullerene formation mechanism, and compare it with modeled Hydrogenated Amorphous Carbon that present emission in this region.Comment: 13 pages, 2 tables, 7 figures, Accepted for publication in Ap

Estratigrafía del Cretácico en el sondeo del Sifón de los Yesos (Torrelaguna) y su correlación con afloramientos de superficie

Several hydrogeological boreholes for survey purposes have been drilled by the Canal de Isabel 11 near Torrelaguna (Madrid). One of those boreholes, at the Sifón de los Yesos, was drilled out with complete core recovering and cut across detrital and evaporitic rocks of Paleogene age and, partly, the Upper Cretaceous series mainly composed of dolostones, marls and sandstones. Six units have been distinguished in the Cretaceous of the borehole, from base to top: 1) Marls and dolostones with minor sandy intercalations (23.6 m); 2) Thick-bedded yellow dolostones (23.4 m); 3) marly dolostones and marls with minor dolostones (8 m); 4) thick-bedded yellow dolostones (17.4 m); 5) medium to thick-bedded white dolostones (21.3 m); and 6) Calcareous breccias alternating with white dolostones and red mudstones (28.5 m). These units have been correlated with the nearby Barranco de las Cuevas section, which is a key section in order to understand the stratigraphical relationships for the Cretaceous south of the Central System, because of several lithostratigraphical units are poorly dolomitized here and thus their facies and sedimentary environments of deposition can be studied and understood. From base to top borehole unit l is correlated with the Tranquera Fm.; borehole units 2, 3 and 4 (lower part) are correlated with Hortezuelos Fm.; borehole units 4 (upper part) and 5 are correlated with Hontoria del Pinar Fm.; and finally, borehole unit 6 is correlated with Burgo de Osma Fm. There are clear differences between these units in surface outcrop and in the borehole relating to colour, which is related to the organic matter content and its oxidation state, and appearance, marly intercalations are weak intervals in surface meanwhile correspond to harder and more compacted intervals in the borehole. The recognition of the borehole facies for the Cretaceous is a very useful stratigraphical tool for future drilling campaigns allowing a more detailed interpretation of the cores.En el Sifón de los Yesos (Torrelaguna), el Canal de Isabel II ha realizado un sondeo de reconocimiento hidrogeológico de 225 m de profundidad con recuperación de testigo continuo. En él se atraviesan materiales detrítico-evaporíticos paleógenos y la sucesión del Cretácico superior en facies dolomíticas muy monótonas en las que se han reconocido 6 unidades estratigráficas informales que de base a techo son: 1) Margas y dolomías tableadas con algunas intercalaciones arenosas (23,6 m); 2) Dolomías amarillas en bancos gruesos (23,4 m); 3) Dolomías margosas y margas grises (8 m); 4) Dolomías amarillas en bancos gruesos (17,4 m); 5) Dolomías blancas en bancos de tamaño medio a grueso (21,3 m); y 6) Brechas calcáreas alternando con calizas blancas y arcillas rojas (28,5 m). La correlación de estas unidades con las establecidas en un afloramiento de superficie cercano -el Barranco de las Cuevas (Patones, Madrid), que debido a su bajo grado de dolomitización se convierte en una sección clave para la interpretación del Cretácico del Borde sur del Sistema Central- permite establecer las unidades litoestratigráficas de los materiales atravesados en el sondeo. La unidad del sondeo 1) se correlaciona con la Fm. Tranquera; las unidades 2), 3) y la parte inferior de la 4) con la Fm. Hortezuelos; el resto de la unidad 4) y la unidad 5) se correlaciona con la Fm. Hontoria del Pinar; y finalmente la unidad 6) con la Fm. Burgo de Osma. Sobre estas unidades litoestratigráficas se establecen 3 secuencias deposicionales pudiendo precisar la edad de los materiales del sondeo (Turoniense superior-Campaniense inferior). La correlación de ambas secciones ayuda a interpretar mejor el origen de las superficies ferruginosas; a precisar las discontinuidades estratigráficas que limitan las secuencias deposicionales; y a señalar diferencias texturales y estructurales notables entre las facies de sondeo y las de superficie, tales como el diferente grado de coloración de los materiales, relacionado con el contenido en materia orgánica y su oxidación en superficie, o el diferente comportamiento reológico de los tramos margosos blandos que en profundidad se manifiestan como intervalos calcáreos más duros y compactados. El reconocimiento de las facies de sondeo del Cretácico superior de esta región se convierte en una herramienta de trabajo muy útil en futuras campañas de perforación permitiendo un seguimiento más detallado a pie de pozo

Central star formation and metallicity in CALIFA interacting galaxies

We use optical integral-field spectroscopic (IFS) data from 103 nearby galaxies at different stages of the merging event, from close pairs to merger remnants provided by the CALIFA survey, to study the impact of the interaction in the specific star formation and oxygen abundance on different galactic scales. To disentangle the effect of the interaction and merger from internal processes, we compared our results with a control sample of 80 non-interacting galaxies. We confirm the moderate enhancement (2-3 times) of specific star formation for interacting galaxies in central regions as reported by previous studies; however, the specific star formation is comparable when observed in extended regions. We find that control and interacting star-forming galaxies have similar oxygen abundances in their central regions, when normalized to their stellar masses. Oxygen abundances of these interacting galaxies seem to decrease compared to the control objects at the large aperture sizes measured in effective radius. Although the enhancement in central star formation and lower metallicities for interacting galaxies have been attributed to tidally induced inflows, our results suggest that other processes such as stellar feedback can contribute to the metal enrichment in interacting galaxies.Comment: 9 pages, 9 figures. Accepted for publication in Astronomy & Astrophysic

Magnetic nanoparticles with bulk-like properties

The magnetic behavior of $Fe_{3-x}O_4$ nanoparticles synthesized either by high-temperature decomposition of an organic iron precursor or low-temperature co-precipitation in aqueous conditions, is compared. Transmission electron microscopy, X-ray absorption spectroscopy, X-ray magnetic circular dichroism and magnetization measurements show that nanoparticles synthesized by thermal decomposition display high crystal quality and bulk-like magnetic and electronic properties, while nanoparticles synthesized by co-precipitation show much poorer crystallinity and particle-like phenomenology, including reduced magnetization, high closure fields and shifted hysteresis loops. The key role of the crystal quality is thus suggested since particle-like behavior for particles larger than about 5 nm is only observed when they are structurally defective. These conclusions are supported by Monte Carlo simulations. It is also shown that thermal decomposition is capable of producing nanoparticles that, after further stabilization in physiological conditions, are suitable for biomedical applications such as magnetic resonance imaging or bio-distribution studies.Comment: Review article. 20 pages, 7 figures. Invited contribution to 55th MMM Conference 2010 (Atlanta), Session HG-01. To be published in J. Appl. Phy