Bubble bursting jets are driven by the purely inertial collapse of gas cavities

The analysis of numerical simulations describing the collapse of capillary cavities reveals that the jets originated from the bursting of bubbles are driven by the condition that the dimensionless liquid flow rate per unit length directed towards the axis of symmetry, $q_\infty$, remains nearly constant in time. This observation, which is justified in physical terms because liquid inertia prevents appreciable changes in $q_\infty$ during the short time scale characterizing the jet ejection process, together with the fact that bubble bursting jets are produced from the bottom of a conical cavity, justify the purely inertial scalings for the jet width and velocity found here, $r_{jet}\propto\sqrt{q_\infty\tau}$ and $v_{jet}\propto \sqrt{q_\infty/\tau}$, with $\tau$ indicating the dimensionless time after the jet is ejected, a result which notably differs from the common belief that the jet width and velocity follow the inertio-capillary scaling $r_{jet}\propto \tau^{2/3}$ and $v_{jet}\propto \tau^{-1/3}$. Our description reproduces the time evolution of the jet width and velocity for over three decades in time, obtaining good agreement with numerical simulations from the instant of jet inception until the jet width is comparable to that of the initial bubble.Comment: 15 pages, 10 figures. Figures are revised and properly referenced (v100323

Control of magnetic domain wall motion in Co microwires by tridimensional e-beam lithographied structures

Resumen del póster presentado al 6th Spanish Workshop in Nanolithography celebrado en Zaragoza (España) del 28 al 30 de octubre de 2014.Work supported by the Spanish MICINN FIS2008-06249 and CSIC JAE Predoc grants.Peer Reviewe

Influence of Distillation System, Oak Wood Type, and Aging Time on Composition of Cider Brandy in Phenolic and Furanic Compounds

A control of phenolic and furanic compounds in cider brandy was carried out during maturation in oak casks, studying three technological factors: distillation (rectification column vs double distillation), oak wood type (French vs American), and aging time (32 months). Gallic acid and benzoic and cinnamic aldehydes significantly increased during maturation of cider brandies, the highest level of these phenolics being obtained when aging was conducted in French oak casks. Benzoic acids increased during aging, though furanic compounds were not influenced by the time factor. Distillation and wood factors significantly influenced furanic concentration; 5-hydroxymethylfurfural not was detected in fresh spirits and was extracted in the highest proportion in French oak. Volatile furanics, such as 5-methylfurfural, furfural, and 2-furylmethyl ketone, were influenced by the distillation factor, with the use of the double distillation system producing a higher level of these compounds. Scopoletin was the majority coumarin detected in cider brandies, the highest yield of which was obtained with the use of American oak

Influence of Distillation System, Oak Wood Type, and Aging Time on Volatile Compounds of Cider Brandy

A study of the influence of distillation system, oak wood type, and aging time on volatile compounds of cider brandy was carried out. Acetaldehyde and acetaldehyde diethyl acetal were influenced by distillation technology, oak wood type, and maturation time. The majority ester, ethyl ethanoate, increased during aging, the highest level of this ester being detected in spirits distilled by double distillation. The alcohols of higher molecular weight were better recovered in the rectification column than in the double distillation system. Ethanoate esters decreased throughout aging of the spirits, and their degradation velocity was lower in distillates obtained from double distillation. Fatty acids and their ethyl esters presented the opposite evolution during aging, detecting an increase in ethyl esters and a decrease in their corresponding fatty acids. An increase of 1,1,3-triethoxypropane was detected during aging. French oak contributes the trans isomer of β-methyl-γ-octalactone and American oak contributes the cis isomer

Parabolic trough collectors. Fundamentals of heat transfer applied to solar thermal energy.

Solar thermal energy has undergone major development in recent years. The most widely used technologies are central receiver solar towers and parabolic trough collectors (PTC)[1]. The latter technology has great advantages due to its higher optical and thermal efficiency, but, despite being a well-proven technique, it presents certain problems inherent to the manufacturing and durability of some critical elements in the system. They are generally composed of an absorber tube surrounded by a glass cover and in the intermediate space, a vacuum is created to minimize thermal losses by convection[2]. The absorber tube is located at the focal line of a parabolic mirror that concentrates sun’s rays. To predict the thermal behavior of this type of system, ray-tracing techniques are used to determine the thermal load and accurate correlations are also needed to calculate the convective heat transfer. Also, the original design shows some problems such as the selective coating applied on the absorber surface, whose thermal performance decays with time. Besides, the metal-glass welding are also a significant weak spot, which due to the thermal expansion can cause the partial or total loss of the vacuum in the aforementioned annulus. In this work we present the results of the modeling of this type of systems in different working configurations, as well as a new design proposal to improve the thermal transfer in this type of systems.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Estudio de tumores de la cavidad nasal y senos paranasales del perro mediante tomografía computarizada

En 8 perros se estudiaron imágenes de tomografía computarizada (TC), analizando la extensión de tumores de cavidad nasal y/o senos paranasales. La técnica resultó especialmente útil en animales con descarga nasal crónica, protrusión del globo ocular, ceguera de origen central o signos de disfunción neurológica por afectación de porciones rostrales del encéfalo.

Surface mesoscale pico–nanoplankton patterns at the main fronts of the Alboran Sea

© 2014 Elsevier B.V. The mesoscale (10-100. km, days-weeks) plays a key role in the Ocean's ecosystem structure and dynamics. This work compares the pico-nanoplankton patterns observed in the Alboran Sea (Western Mediterranean) during three oceanographic cruises. We analyse its response to different expressions of mesoscale circulation associated with the three major hydrodynamic features in the basin; namely the Northwestern Alboran Front (NWAF, surveyed in OMEGA-1 cruise), the Almeria-Oran Front (AOF, surveyed in OMEGA-2 cruise) and the Western Alboran Gyre (WAG, surveyed in BIOMEGA cruise). The first two surveys were carried out under the most typical quasi-stationary twin gyre conditions of the Alboran Sea, whereas the third cruise was performed after an eastward migration of the WAG. The analysis of pico and nanoplankton populations was carried out using flow cytometry. The patchiness observed in the three cruises indicates an association of phytoplankton peaks with the main frontal structures: abundances were higher in the NWAF/upwelling area in OMEGA-1, at the Mediterranean side of the AOF in OMEGA-2, and at a tongue of recent Atlantic Water west of the WAG in BIOMEGA. However, a more detailed analysis reveals that different factors explain the origin of the phytoplankton biomass in each front/cruise. Mixing processes at the Strait of Gibraltar and the subsequent advection of water properties into the Western Alboran Sea were the mechanisms responsible for the abundances observed in the NWAF. The highest concentrations observed in the AOF were related to the intrusion of Mediterranean Surface Waters to the north of the front. During the migrating WAG the phytoplankton distribution was influenced by the formation of a new gyre. The relation between phytoplankton and mesoscale dynamics is further explored in terms of vertical velocity diagnosis. In all cases, intense vertical motion is negatively correlated with the abundance of phytoplankton populations. This resulted from the intense geostrophic background flow associated with large vertical velocities, which drove low residence times of water mass properties and hence a weak biological response. Fast-repeated surveys made during the OMEGA-1 and OMEGA-2 cruises reveal that the surveyed hydrographic features are subjected to significant temporal variability. In this case, the impact on the biology is most evident at taxa level.This work was partially supported by the EU funded MAST project OMEGA (MAS3-CT95-0001) and by the BIOMEGA project, funded by the Spanish Marine Science and Technology Program (REN2002-04044-C02-02). P. Leon was financed by a FPI grant from the Spanish Ministry of Education and Science (BES-2003-1032)Peer Reviewe

Enhancing the hydrogen transfer catalytic activity of hybrid carbon nanotube-based NHC–iridium catalysts by increasing the oxidation degree of the nanosupport

CVD-grown multiwalled carbon nanotubes were purified by applying four different treatments with increasing oxidation severity. The growing severity of the treatment results in progressive oxygen functionalization of the surface along with introduction of an increasing quantity of defects on the carbon nanotube walls. Iridium-N-heterocyclic carbene complexes were covalently anchored to those oxidized surfaces through their surface carboxylic acids via acetyl linkers. The carbon nanotube-based iridium-NHC hybrid materials developed are active in the hydrogen-transfer reduction of cyclohexanone to cyclohexanol with 2-propanol/KOH as hydrogen source but with rather different activity. The catalytic activity of the hybrid catalysts is strongly influenced by the type and amount of oxygenated functionalization resulting from the treatment applied to the support, being the most active and the most oxidized material.The authors thank the Spanish Ministry of Economy and Competitiveness (MINECO/FEDER) (Projects Consolider Ingenio 2010 CSD2009-00050 and CTQ2013-42532-P) and the Diputación General de Aragón (FSE-E07 and FSE-E69) for their financial support. Dr. P. A. thanks MINECO for a Ramón y Cajal contract. M. B. acknowledges his fellowship from MECD (AP2010-0025).Peer Reviewe