Ion charge number and flux saturation effects in the corona of a laser-irradiated pellet

The quasisteady structure of the corona of a laser-irradiated pellet is completely determined for arbitrary Z, (ion charge number} and re/ra (ratio of critical and ablation radii), and for heat-flux saturation factor/above approximately 0.04. The ion-to-electron temperature ratio at rc grows sensibly with Z,; all other quantities depend weakly and nonmonotonically on Z,. For rc /ra close to unity, and all Z, of interest (Z, < 47}, the flow is subsonic at rc. For a given laser power W, flux saturation may decrease (low/) or increase (high/) the ablation pressure Pa relative to the value obtained when saturation is not considered; in some cases a decrease in/with W fixed increases Pa. For intermediate^ ~0.1), Pa cc (W/r* )2/3 p\n\pc = critical density), independently of rc/ra; for/~0.6, Pa «s larger by a factor of about [rc/raf13. For rjra > 1.2 roughly, the mass ablation rate is C{Z,) [{m/kZ.f^Kr^Pl) l,\ independent of pc and/, and barely dependent on Z,(m, is ion mass; k, Boltzmann's constant; K, conductivity coefficient; and C, a tabulated function)

Thermal self-focusing instability in the conduction layer of a laser target

Refraction is included in the stability analysis of the corona ablated from a laser target, assuming conduction restricted to a thin layer and absorption at the critical density inside it. A thermal self-focusing instability, with growth rate ~ (ion-electron collision frequency) X (electron-to-ion mass ratio), is found

Non-uniform target illumination in deflagration regime : thermal smoothing

Thermal smoothing in the plasma ablated from a laser target under weakly nonuniform irradiation is analyzed, assuming absorption at nc and a deflagration regime (conduction restricted to a thin quasisteady layer next to the target). Magnetic generation effects are included and found to be weak. Differences from results available in the literature are explained; the importance of the character of the underdense flow at uniform irradiation is emphasized

Two-temperature model of the coronal irradiated pellets

A two electron-temperature, quasi-steady model of the corona of a laser-ablated pellet is considered. Ablation pressure, critical radius and mass flow rate are determined. Results are close to those obtained with heat flux saturation well below the free-streaming limit

Antibacterial and antifungal activity of ZnO containing glasses

A new family of non-toxic biocides based on low melting point (1250°C) transparent glasses with high content of ZnO (15–40wt%) belonging to the miscibility region of the B2O3-SiO2-Na2O-ZnO system has been developed. These glasses have shown an excellent biocide activity (logarithmic reduction >3) against Gram- (E. coli), Gram+ (S. aureus) and yeast (C. krusei); they are chemically stable in different media (distilled water, sea-like water, LB and DMEN media) as well as biocompatible. The cytotoxicity was evaluated by the Neutral Red Uptake using NIH-3T3 (mouse embryonic fibroblast cells) and the cell viability was >80%. These new glasses can be considered in several and important applications in the field of inorganic non-toxic biocide agents such as medical implants, surgical equipment, protective apparels in hospitals, water purifications systems, food packaging, food storages or textiles.This study has been supported by Consejo Superior de Investigaciones Cientificas (CSIC) project reference number 201360E012 and by the Spanish Ministry of Science and Innovation MAT2012-38645. C. Prado and B. Cabal acknowledge financial support from JAE-Doc program (CSIC, cofounded by FSE).Peer Reviewe

Diseño de Plataformas Moleculares Multifuncionales

El boro es un elemento que forma compuestos químicos que presentan enlaces de tres centros y dos electrones, de tipo B-H-B o B-B-B como, por ejemplo, el anión octahidrotriborato, B3H8-.El anión octahidrotriborato es un compuesto muy importante en la química del boro, ya que es un intermedio de reacción en la síntesis de boranos superiores y de diversos complejos de metales de transición. También cabe destacar que este anión, en disolución, es fluxional, ya que todos los átomos de hidrógeno, presentes en la molécula, se intercambian en el tiempo de escala de los experimentos de Resonancia Magnética Nuclear (RMN) de 1H; el mecanismo de intercambio que se ha propuesto en la bibliografía consiste en una pseudorrotación del grupo BH2.Una de las formas más estables en las que se puede encontrar el anión es como CsB3H8 o ((n-С4H9)4N)[B3H8]. Estas sales se pueden utilizar para sintetizar metalaboranos de B3H8-, que son complejos de metal en donde el anión triborato funciona como ligando. Una síntesis interesante de este tipo es la que ha permitido obtener la molécula de rodatetraborano, [Rh(η2-B3H8)(H)2(PPh3)2].El rodatetraborano es un complejo de Rh(III) en donde el B3H8-, actúa como un ligando quelato bidentado. Este metalaborano, en disolución, también presenta comportamientos fluxionales, que han sido estudiados y caracterizados por RMN. A temperaturas superiores a los 290 K, se produce la apertura de los enlaces B-H-B y la migración de los átomos de H terminales de manera sincronizada.<br /

Towards discard quantification of Data Limited Stocks based in on-board observers data: the case of Spanish fresh trawlers targeting black hake in NW Africa

Quantification of discard per unit effort rates (DPUE) has been proposed by the European Commission as a measure to manage the discarding of commercially fished organisms. In the Spanish fresh trawling fleet operating in North West Africa, both target species of black hakes, Merluccius polli and Merluccius senegalensis are data limited stocks (DLS). Hence, discards of these fleets are even more unknown but not unimportant part of the total catch (retained and discarded). Onboard observer data from commercial surveys from 2016 to 2018 provide a detailed source of scientific information about catches, discards, effort and technical factors in this fleet. This is the first quantitative analysis to model DPUE through generalised linear mixed models (GLMM), based on the explicit distinction between abundance and technical factors coming from information of observer surveys. We describe the relationship between discards and environment, catches of target and other species, effort of the fleet, spatial and temporal variation in discard accessibility, vessel characteristics, strategy of the skippers and market decisions. Unlike hake catches, discards were higher and more dispersed in shallower than in deeper waters. We identified two separate métiers for the Spanish fresh trawling fleet determined by depth and treated total discards as a stock unit susceptible of being monitored, managed and assessed. The strategy of the skipper appears to have a more important effect on discards than vessel characteristics. This study shows the importance of observer data for this fishery and identifies recommendations for the improvement in the scientific usefulness of logbook information.En prens

Reactividad del decaborano con bases de Brønsted y compuestos de plata: Estudios estructurales y espectroscópicos

En este TFG se ha sintetizado la sal de Proton Sponge, [PSH][B10H13]. Los reactivos empleados, decaborano y Proton Sponge, son solubles en hexano y se disolvieron individualmente, y tras verter la base sobre el decaborano, B10H14, se observó la precipitación instantánea de la sal. Así, este procedimiento de síntesis es una forma nueva y conveniente de preparar una sal de decaborano, que es estable al aire, y fácil de pesar y manipular. Se ha observado por primera vez en el sistema nido-decaborano, el movimiento tautomérico de los átomos de hidrógeno puente de su estructura. El clúster aniónico, [B10H13]-, presenta procesos fluxionales en los que intervienen los átomos de hidrógeno puente, y se ha podido caracterizar con detalle que los tres átomos de hidrógeno puente de su estructura participan en un intercambio de posición continuo con movimiento constante alrededor de la cara hexagonal del clúster. La obtención de la sal se debe a la abstracción de un átomo de hidrógeno puente del decaborano por la base Proton Sponge. Cabría esperar que la base atacara acercándose por la parte de arriba de la cara hexagonal del B10H14, donde se encuentran los átomos de hidrógeno ácidos; pero los cálculos DFT indican que las configuraciones de menor energía son aquellas en las que el catión interacciona con la periferia del clúster. Este hecho nos hace sugerir que la base, PS, podría capturar el protón también en la periferia del clíster, cerca de los átomos terminales, disminuyendo así las repulsiones estéricas entre el clúster poliédrico y la base orgánica. La sal de decaborano es un producto de partida útil para el estudio de su reactividad con moléculas orgánicas, complejos metálicos, etc

Evaluation of dimensionality reduction methods applied to numerical weather models for solar radiation forecasting

The interest in solar radiation prediction has increased greatly in recent times among the scientific community. In this context, Machine Learning techniques have shown their ability to learn accurate prediction models. The aim of this paper is to go one step further and automatically achieve interpretability during the learning process by performing dimensionality reduction on the input variables. To this end, three non standard multivariate feature selection approaches are applied, based on the adaptation of strong learning algorithms to the feature selection task, as well as a battery of classic dimensionality reduction models. The goal is to obtain robust sets of features that not only improve prediction accuracy but also provide more interpretable and consistent results. Real data from the Weather Research and Forecasting model, which produces a very large number of variables, is used as the input. As is to be expected, the results prove that dimensionality reduction in general is a useful tool for improving performance, as well as easing the interpretability of the results. In fact, the proposed non standard methods offer important accuracy improvements and one of them provides with an intuitive and reduced selection of features and mesoscale nodes (around 10% of the initial variables centered on three specific nodes).This work has been partially supported by the projects TIN2014-54583-C2-2-R, TEC2014-52289-R and TEC2016-81900-REDT of the Spanish Interministerial Commission of Science and Technology (MICYT), and by Comunidad Autónoma de Madrid, under project PRICAM P2013ICE-2933

Synthesis and Characterisation of ASA-PEEK Composites for Fused Filament Fabrication

In this paper, a series of polymer composites made from acrylonitrile-styrene-acrylate (ASA) and poly (ether ether ketone) (PEEK) were manufactured. ASA acts as a polymer matrix while PEEK is loaded in the form of micro-particles that act as a reinforcing filler. The composites were compounded by single screw extrusion and then, different specimens were manufactured either via injection moulding (IM) or fused filament fabrication (FFF). Two different types of PEEK (commercial and reused) in different concentrations (3 and 6 wt.%) were tested and their influence in the mechanical, structural, and thermal properties were studied. It was observed that reused PEEK enhanced the stiffness and tensile strength and thermal stability of the composites both, for injected and printed specimens. This evidences the suitability of these composites as potential candidates as novel materials with enhanced properties following an approach of circular economy