Population synthesis of isolated Neutron Stars with magneto--rotational evolution

We revisit the population synthesis of isolated radio-pulsars incorporating recent advances on the evolution of the magnetic field and the angle between the magnetic and rotational axes from new simulations of the magneto-thermal evolution and magnetosphere models, respectively. An interesting novelty in our approach is that we do not assume the existence of a death line. We discuss regions in parameter space that are more consistent with the observational data. In particular, we find that any broad distribution of birth spin periods with $P_0\lesssim 0.5$ s can fit the data, and that if the alignment angle is allowed to vary consistently with the torque model, realistic magnetospheric models are favoured compared to models with classical magneto-dipolar radiation losses. Assuming that the initial magnetic field is given by a lognormal distribution, our optimal model has mean strength $\langle\log B_0{\rm [G]}\rangle \approx 13.0-13.2$ with width $\sigma (\log B_0) = 0.6-0.7$. However, there are strong correlations between parameters. This degeneracy in the parameter space can be broken by an independent estimate of the pulsar birth rate or by future studies correlating this information with the population in other observational bands (X-rays and $\gamma$-rays).Comment: 10 pages, 9 figures, submitted and accepted to MNRAS, comments welcom

Population Synthesis of Isolated Neutron Stars with magneto-rotational evolution II: from radio-pulsars to magnetars

Population synthesis studies constitute a powerful method to reconstruct the birth distribution of periods and magnetic fields of the pulsar population. When this method is applied to populations in different wavelengths, it can break the degeneracy in the inferred properties of initial distributions that arises from single-band studies. In this context, we extend previous works to include $X$-ray thermal emitting pulsars within the same evolutionary model as radio-pulsars. We find that the cumulative distribution of the number of X-ray pulsars can be well reproduced by several models that, simultaneously, reproduce the characteristics of the radio-pulsar distribution. However, even considering the most favourable magneto-thermal evolution models with fast field decay, log-normal distributions of the initial magnetic field over-predict the number of visible sources with periods longer than 12 s. We then show that the problem can be solved with different distributions of magnetic field, such as a truncated log-normal distribution, or a binormal distribution with two distinct populations. We use the observational lack of isolated NSs with spin periods P>12 s to establish an upper limit to the fraction of magnetars born with B > 10^{15} G (less than 1\%). As future detections keep increasing the magnetar and high-B pulsar statistics, our approach can be used to establish a severe constraint on the maximum magnetic field at birth of NSs.Comment: 12 pages, 11 figures, 5 table

Contribución al estudio de las Lemnáceas de Huelva (Andalucía occidental, España)

La superficie de humedales presentes en Huelva concentra la mayor proporción de zonas húmedas de Andalucía con 54.825 ha de superfi cie palustre (77,39%). Esta riqueza y diversidad de medios acuáticos posibilitan la localización de numerosas plantas acuáticas y la conservación de humedales tan emblemáticos como el Parque Nacional de Doñana, el Paraje Natural Marismas del Odiel, o las Turberas de Las Madres. Se estudian 7 Lemnáceas presentes en la provincia de Huelva (Andalucía Occidental, España), citándose como novedad regional para Andalucía Lemna valdiviana Phil., especie americana naturalizada en diversos puntos de la Península Ibérica. Se estudia la distribución de este grupo de macrófi tos en la provincia, y se amplía la distribución conocida de Wolffi a arrhiza (L.) Horkel ex Wimm., Lemna trisulca L., y Spirodela polyrrhiza (L.) Schleind., especies amenazadas en España.The main dimension of humid areas in Andalucia are present in Huelva province with 54.825 ha (77,39%). This richness and diversity in aquatic environments make possible the location of numerous aquatic plants, and the conservation of emblematic wetlands as Parque Nacional de Doñana, Paraje Natural Marismas del Odiel or Turberas de Las Madres. The distribution of 7 species of the Duckweed Family, present in the Huelva province (Occidental Andalusia, Spain), are studied. Lemna valdiviana Phil., an American species, is presented as a regional novelty for the Andalusian fl ora, and the known distribution of Wolffi a arrhiza (L.) Horkel ex Wimm., Lemna trisulca L. and Spirodela polyrrhiza (L.) Schleind., 3 threatened species from Spain, is extended.proyecto “Flora iberica VIII” CGL2008-02982-C03-01/CLI, Ministerio de Ciencia e Innovació

Electrocatalysis on shape-controlled metal nanoparticles: Progress in surface cleaning methodologies

The use of shape-controlled metal nanoparticles has produced not only a clear enhancement in the electrocatalytic activity of different reactions of interest but also a better understanding of the effect of the surface structure on nanoscaled materials. However, it is well-accepted that a correct understanding of the correlations between shape/surface structure and electrochemical reactivity indispensably requires the use of clean surfaces. In this regard, and considering that most of the synthetic methodologies available in the literature for the preparation of these shaped metal nanoparticles employ capping agents, the development of effective surface cleaning methodologies able to remove such capping agents from the surface of the corresponding nanoparticles, becomes an extremely important prerequisite to subsequently evaluate their electrocatalytic properties for any reaction of interest. Consequently, in this contribution, we summarize the most relevant advances about surface cleaning procedures applied to different shaped metal nanoparticles for electrocatalytic purposes. It is worth mentioning that this work will only include contributions in which the surface cleanness of the samples is specifically evaluated using well-established electrochemical tools.This work has been financially supported by the MINECO of Spain through project CTQ2013-48280-C3-3-R. JSG acknowledges financial support from VITC (Vicerrectorado de Investigación y Transferencia de Conocimiento) of the University of Alicante

In vitro gastrointestinal digestion of pomegranate peel (Punica granatum) flour obtained from co-products: changes in the antioxidant potential and bioactive compounds stability

The effect of in vitro gastrointestinal digestion (GID) on the recovery, bioaccessibility and stability of polyphenolic compounds, the changes in antioxidant activity and the short chain fatty acids (SCFAs) production of pomegranate peel flour (PPF) were evaluated. The extracts obtained in each step of GID were used to determine the stability of polyphenolic profile using HPLC whilst the antioxidant properties were determined using five methodologies. The SCFAs production from PPF fermentation was also determined. At the end of GID process, the bioaccessibility of phenolic and flavonoid compounds was 35.90 and 64.02%, respectively. The polyphenolic compounds decreased after GID except that for ellagic acid which increased. GID increased the chelating activity and reducing power. However, the scavenging properties were reduced. Fermentation of PPF by colonic bacteria generated acetic, propionic and butyric acids. PPF could be used in the food industry as a potential ingredient to develop functional foods that promote health benefits.info:eu-repo/semantics/publishedVersio

Bragg Coherent Diffraction Imaging for In Situ Studies in Electrocatalysis

Electrocatalysis is at the heart of a broad range of physicochemical applications that play an important role in the present and future of a sustainable economy. Among the myriad of different electrocatalysts used in this field, nanomaterials are of ubiquitous importance. An increased surface area/volume ratio compared to bulk makes nanoscale catalysts the preferred choice to perform electrocatalytic reactions. Bragg coherent diffraction imaging (BCDI) was introduced in 2006 and since has been applied to obtain 3D images of crystalline nanomaterials. BCDI provides information about the displacement field, which is directly related to strain. Lattice strain in the catalysts impacts their electronic configuration and, consequently, their binding energy with reaction intermediates. Even though there have been significant improvements since its birth, the fact that the experiments can only be performed at synchrotron facilities and its relatively low resolution to date (∼10 nm spatial resolution) have prevented the popularization of this technique. Herein, we will briefly describe the fundamentals of the technique, including the electrocatalysis relevant information that we can extract from it. Subsequently, we review some of the computational experiments that complement the BCDI data for enhanced information extraction and improved understanding of the underlying nanoscale electrocatalytic processes. We next highlight success stories of BCDI applied to different electrochemical systems and in heterogeneous catalysis to show how the technique can contribute to future studies in electrocatalysis. Finally, we outline current challenges in spatiotemporal resolution limits of BCDI and provide our perspectives on recent developments in synchrotron facilities as well as the role of machine learning and artificial intelligence in addressing them.Financial support from Brazilian agencies: P.S.F. thanks FAPESP (Grants 2017/11986-5, 2018/20952-0, and 2019/13888-6 (RAV fellowship)), CNPq (Grant136436/2019-6 (RAV fellowship)), Shell, and the strategic importance of the support given by ANP (Brazil’s National Oil, Natural Gas and Biofuels Agency) through the R&D levy regulation. Use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences Data, Artificial Intelligence and Machine Learning at DOE Scientific User Facilities program under Award No. 34532

Exploiting the potential of bioactive molecules extracted by ultrasounds from avocado peelsfood and nutraceutical applications

Natural bioactive compounds from food waste have fomented interest in food and pharmaceutical industries for the past decade. In this work, it purposed the recovery of bioactive avocado peel extract using an environmentally friendly technique: the ultrasound assisted extraction. The response surface methodology was applied in order to optimize the conditions of the extraction, ethanol-water mixtures and time. The optimized extracts (ethanol 38.46%, 44.06 min, and 50 °C) were chemically characterized by HPLC-ESI-MS and FTIR. Its antioxidant ability, as well as, its effect on cell metabolic activity of normal (L929) and cancer (Caco-2, A549 and HeLa) cell lines were assessed. Aqueous ethanol extracts presented a high content in bioactive compounds with high antioxidant potential. The most representative class of the phenolic compounds found in the avocado peel extract were phenolic acids, such as hydroxybenzoic and hydroxycinnamic acids. Another important chemical group detected were the flavonoids, such as flavanols, flavanonols, flavones, flavanones and chalcone, phenylethanoids and lignans. In terms of its influence on the metabolic activity of normal and cancer cell lines, the extract does not significantly affect normal cells. On the other hand, it can negatively affect cancer cells, particularly HeLa cells. These results clearly demonstrated that ultrasound is a sustainable extraction technique, resulting in extracts with low toxicity in normal cells and with potential application in food, pharmaceutical or nutraceutical sectors.The authors acknowledge the financial support received from “Xunta de Galicia” (GRC ED431C 2017/62-GRC, and Project ED431F 2020/03). These projects are partially funded by the FEDER Program of the European Union (“Unha maneira de facer Europa”). This research was also funded by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit. Beatriz Gullón would like to express her gratitude to the Spanish Ministry of Economy and Competitiveness for her postdoctoral grant (Reference RYC2018-026177-I).info:eu-repo/semantics/publishedVersio