Bacterial behavior on coated porous titanium substrates for biomedical applications

In this work, bacterial behavior on dense and porous titanium substrates is discussed. Porous titanium was fabricated by a space holder technique (using 50 vol%, NH4HCO3 with particle sizes between 250 and 355 μm). These substrates were coated by sulfonated PEEK (termed SPEEK). Characterization of the porous substrate was carried out using the Archimedes Method, Image Analysis, and three-dimensional X-ray Micro-Computed Tomography (including total and interconnected porosity, equivalent diameter, and pore shape factor), as well as mechanical characterization (specifically stiffness and yield strength). A detailed study was performed here to investigate the influence of substrate porosity on the adhesion and proliferation of E. coli, MRSA, and P. aeruginosa (common causes of orthopedic device-associated infections). Bacterial colonization was examined in terms of the initial bacterial concentration, as well as bacterial adherence to and growth on the surface and inside the pores. Results suggest that fully dense titanium supported the least bacterial colonization, while the porous titanium promoted bacterial growth in the medium and inside the cavities. Furthermore, the SPEEK coating deposited onto the samples inhibited bacteria growth inside the porous materials. In this manner, this study showed for the first time that SPEEK could have potential antibacterial properties to offset the increase in bacteria growth commonly observed in porous materials.Junta de Andalucía-FEDER (Spain) Ref. P12-TEP-1401Ministry of Economy and Competitiveness of Spain, MAT2015-71284-

The ISLANDS project I: Andromeda XVI, An Extremely Low Mass Galaxy not Quenched by Reionization

Based on data aquired in 13 orbits of HST time, we present a detailed evolutionary history of the M31 dSph satellite Andromeda XVI, including its life-time star formation history, the spatial distribution of its stellar populations, and the properties of its variable stars. And XVI is characterized by prolonged star formation activity from the oldest epochs until star formation was quenched ~6 Gyr ago, and, notably, only half of the mass in stars of And XVI was in place 10 Gyr ago. And XVI appears to be a low mass galaxy for which the early quenching by either reionization or starburst feedback seems highly unlikely, and thus, is most likely due to an environmental effect (e.g., an interaction), possibly connected to a late infall in the densest regions of the Local Group. Studying the star formation history as a function of galactocentric radius, we detect a mild gradient in the star formation history: the star formation activity between 6 and 8 Gyr ago is significantly stronger in the central regions than in the external regions, although the quenching age appears to be the same, within 1 Gyr. We also report the discovery of 9 RR Lyrae stars, 8 of which belong to And XVI. The RR Lyrae stars allow a new estimate of the distance, (m-M)0= 23.72+/-0.09 mag, which is marginally larger than previous estimates based on the tip of the red giant branch.Comment: Accepted for publication on Ap

RR Lyrae mid-infrared Period-Luminosity-Metallicity and Period-Wesenheit-Metallicity relations based on Gaia DR3 parallaxes

We present new empirical infrared Period-Luminosity-Metallicity (PLZ) and Period-Wesenheit-Metallicity (PWZ) relations for RR Lyrae based on the latest Gaia EDR3 parallaxes. The relations are provided in the WISE $W1$ and $W2$ bands, as well as in the $W(W1, V - W1)$ and $W(W2, V - W2)$ Wesenheit magnitudes. The relations are calibrated using a very large sample of Galactic halo field RR Lyrae stars with homogeneous spectroscopic [Fe/H] abundances (over 1,000 stars in the $W1$ band), covering a broad range of metallicities ($-2.5 \lesssim \textrm{[Fe/H]} \lesssim 0.0$). We test the performance of our PLZ and PWZ relations by determining the distance moduli of both galactic and extragalactic stellar associations: the Sculptor dwarf spheroidal galaxy in the Local Group (finding $\bar{\mu}_{0}=19.47 \pm 0.06$), the Galactic globular clusters M4 ($\bar{\mu}_{0}=11.16 \pm 0.05$) and the Reticulum globular cluster in the Large Magellanic Cloud ($\bar{\mu}_{0}=18.23 \pm 0.06$). The distance moduli determined through all our relations are internally self-consistent (within $\lesssim$ 0.05 mag) but are systematically smaller (by $\sim$ 2-3$\sigma$) than previous literature measurements taken from a variety of methods/anchors. However, a comparison with similar recent RR Lyrae empirical relations anchored with EDR3 likewise shows to varying extents a systematically smaller distance modulus for PLZ/PWZ RR Lyrae relations.Comment: Accepted by ApJ, 14 pages, 5 Figures, 2 Table

SILENCIO: Introduction of electric propulsion to small inshore fishing boats to reduce their impact in the environment

Human activities afects each environment, even the most remote, and the acoustic impact that these activities generate on the marine environment is not an exception. The Silencio project aims to developed innovative and sustainable solutions to reduce the impact of fsheries and shell-fsheries in ecosystems, mainly noise but also carbon footprint, by the assessment of the use of electric propulsion by small inshore fshing boat. Besides, the knowledge about the sources of underwater noise in areas under high fshing pressure will be improved by the characterization of the ambient noise in Rías Baixas. Further, the project will spread the idea of an environmentally sustainable, socially responsible and economically viable extractive sector.Peer Reviewe