Co supported on N and S dual-doped reduced graphene oxide as highly active oxygen-reduction catalyst for direct ethanol fuel cells

Oxygen reduction reaction (ORR) is one of the key features for the efficient functioning of several energy conversion devices such as fuel cells, appearing the necessity of development of new low-cost catalyst materials. Heteroatom-doped carbon materials have attracted attention in this field due to its physicochemical and electronic properties. In this work, a nitrogen and sulfur doped material with anchored Co3O4 nanoparticles (Co/SN-rGO) is proposed as cathode catalyst for direct ethanol fuel cells (DEFCs) and results are compared with different doped graphene nanomaterials (GMs). The effect of the heteroatoms and cobalt oxide nanoparticles in the final efficiency was studied. Synthesized materials were characterized and the activity of Co/SN-rGO and GMs for the ORR was studied. Co/SN-rGO presents high ORR performance in terms of onset potential (Eonset), 0.86 V (vs RHE) and half-wave potential (E1/2) 0.72 V (vs RHE). Tafel analysis shows 60 mV dec-1 at low overpotential for potential dependent ORR mechanism. Besides, when Co/SN-rGO performance is evaluated in a DEFC using a fuel cell test station, main results indicate higher catalytic activity, stability, and ethanol tolerance of Co/SN-rGO in comparison to a carbon-supported Pt catalystThis work has been developed in the framework of the projects PID2020-117586RB-100, PID2020-112594RB-C33, PID2020- 116712RBC21 funded by MCIN/AEI/10.13039/501100011033, and ProID2021010098 funded by the Gobierno de Canarias (FEDER). S. Fajardo acknowledge the MCIN for the pre-doctoral grant (PRE2018- 085718). The authors thank SEGAI-ULL for the collaboratio

Carbon and oxygen in HII regions of the Magellanic Clouds: abundance discrepancy and chemical evolution

We present C and O abundances in the Magellanic Clouds derived from deep spectra of HII regions. The data have been taken with the Ultraviolet-Visual Echelle Spectrograph at the 8.2-m VLT. The sample comprises 5 HII regions in the Large Magellanic Cloud (LMC) and 4 in the Small Magellanic Cloud (SMC). We measure pure recombination lines (RLs) of CII and OII in all the objects, permitting to derive the abundance discrepancy factors (ADFs) for O^2+, as well as their O/H, C/H and C/O ratios. We compare the ADFs with those of other HII regions in different galaxies. The results suggest a possible metallicity dependence of the ADF for the low-metallicity objects, but more uncertain for high-metallicity objects. We compare nebular and B-type stellar abundances and we find that the stellar abundances agree better with the nebular ones derived from collisionally excited lines (CELs). Comparing these results with other galaxies we observe that stellar abundances seem to agree better with the nebular ones derived from CELs in low-metallicity environments and from RLs in high-metallicity environments. The C/H, O/H and C/O ratios show almost flat radial gradients, in contrast with the spiral galaxies where such gradients are negative. We explore the chemical evolution analysing C/O vs. O/H and comparing with the results of HII regions in other galaxies. The LMC seems to show a similar chemical evolution to the external zones of small spiral galaxies and the SMC behaves as a typical star-forming dwarf galaxy.Comment: Accepted for publication in MNRAS, 17 pages, 11 figures, 8 table

Modelos productivos de las denominaciones de origen protegidas de vino en España

El número de Denominaciones de Origen Protegidas de vino ha crecido mucho en España tras la incorporación a la Unión Europea. Nuestro objetivo es identificar modelos productivos diferentes, en función de cómo se combinan los factores de producción. A partir de las estadísticas del Ministerio de Agricultura, se ha construido una base de datos con las variables estructurales más significativas de cada denominación: superficie de viñedo, viticultores y bodegas inscritas; la serie temporal abarca las campañas agrícolas de este siglo. La combinación de factores de producción se expresa mediante dos indicadores obtenidos a partir de dichas variables: el cociente entre superficie y viticultores (tamaño medio de la explotación vitícola) y el cociente entre viticultores y bodegas (polaridad château-cooperativa). Sobre la base de ambos indicadores se ha realizado una clasificación de las denominaciones mediante un análisis clúster. Como resultado, en primer lugar se ha contrastado y evaluado la existencia de grandes diferencias de tamaño entre las denominaciones; en segundo lugar, se han identificado cinco modelos productivos diferentes. De la diversidad observada se concluye que Denominación de Origen Protegida es una figura legal que acoge realidades muy dispares, lo cual puede plantear problemas de gobernanza dentro del sector del vino. The number of wine Protected Designations of Origin has grown a lot in Spain after joining the European Union. Our objective is to identify different production models, depending on how production factors are combined. From the statistics of the Ministry of Agriculture, a database has been constructed with the most significant structural variables of each designation: area of vineyard, vine growers and registered wineries; the time series embraces the agricultural campaigns of 21st century. Combinations of production factors are expressed by two indicators obtained from these variables: the quotient between area and vine growers (average size of the vineyard) and the ratio of vine growers and wineries (château-cooperative polarity). On the basis of both indicators designations have been classified through a cluster analysis. Main findings are: first, the existence of large differences in size among denominations has been contrasted and evaluated; secondly, five different production models have been identified. From the observed diversity, it is concluded that Protected Designation of Origin is a legal entity that overcomes very different realities, which can raise problems of governance within the wine sector

Electrodeposition of Indium on W and Cu electrodes in the Deep Eutectic Solvent choline chloride-ethylene glycol (1:2).

Producción CientíficaA procedure for drying the deep eutectic solvent (DES) choline chloride - ethylene glycol, ChCl-EG (1:2), based on the use of molecular sieves has been developed, being the final water content of the electrolyte 145±5 ppm. In this dried DES, the stability of InCl and InCl3 as well as the electrochemical behaviour of their solutions has been investigated using electrochemical techniques, X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). Experiments performed under a N2 atmosphere show that InCl3, dissolved in the rich chloride media as InClp 3-p, is reduced on a tungsten electrode to indium metal via only one electrochemical step. Conversely, InCl undergoes the following disproportionation reaction when dissolved in the eutectic ChCl-EG (1:2) 3InCl(s) + (p − 3)Cl− ⇌ 2In(0) + InClp − 3 p generating In(0) and giving place to identical electrochemical signals as those obtained after the addition of InCl3 to the DES. On a tungsten electrode, nucleation and crystal growth of In plays an important role in the electrodeposition process. Chronoamperometric results were consistent with instantaneous three dimensional nucleation on a finite number of active sites with diffusion controlled growth of the nuclei, whatever the applied overpotential and temperature. Mass transport towards the electrode is a diffusion process, and the following empirical expression for the temperature dependence of the diffusion coefficient was calculated. LnD = −(3.58 ± 0.22)–(3665 ± 76) T − 1 The electro-reduction of In(III) solutions was also investigated at a copper substrate. The resulting cyclic voltammograms evidenced the formation of In-Cu intermetallic compounds. Hence, In-Cu alloy films were obtained by continuous potentiostatic electrolysis and intensiostatic pulse electrolysis. The obtained samples, characterized by XRD and SEM, revealed the formation of the metastable CuIn phase that could be transformed into Cu11In9 by thermal annealing.Consejería de Educación of the Junta de Castilla y León Project VA171U14 for financial support. S. García, also thanks the youth employment operative programme (European Social Fund, ESF, and youth employment initiative, YEI)

Effects of dry needling on gait and muscle tone in Parkinson''s disease: a randomized clinical trial

Background: Alterations in gait and muscular rigidity are common and disabling in persons with Parkinson''s disease (PD). Objective: The aim of this study was to determine whether a single dry needling (DN) session can promote changes in gait and muscle tone in the lower extremities as well as in the evolution of the disease in persons with PD. Methods: A randomized double-blind clinical trial was designed. Participants were randomly assigned to an intervention group (IG) that received a session of DN over the semitendinosus, medial gastrocnemius, soleus and rectus femoris muscles, or to a control group (CG) that received a session of sham DN in the same muscles. The effects of DN were assessed using the timed up and go test (TUG), 10 meter walk test (10MWT), 6 minute walk test (6MWT) and myotonometry before, immediately after, and 7 days after the intervention. Results: Thirty-three participants were analyzed aged 69.9 +/- 7.2 years (mean +/- SD; 39% female). There were no significant differences between the IG and CG for any outcomes. Significant differences were observed when comparing the Pre and Follow-up values in the IG for functional mobility of gait in the TUG (p = 0.049), gait speed in the 10MWT (p = 0.041) and muscle tone in the lower extremities by myotonometry (frequency (p = 0.027) and stiffness (p = 0.013)). By comparison, there were no significant within-group differences in the CG. Conclusion: A single session of DN had no measurable benefit compared to a single session of sham DN. Within-group changes in the IG suggested improvements in functional mobility of gait and gait speed, as well as changes in the muscle tone in the lower extremities of PD patients, which could be worthy of further exploration by future research

Time resolved confocal luminescence investigations on Reverse Proton Exchange Nd:LiNbO3 channel waveguides

This paper was published in Optics Express and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OE.15.008805. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under la

Estimating the longitudinal magnetic field in the chromosphere of quiet-Sun magnetic concentrations

Details of the magnetic field in the quiet Sun chromosphere are key to our understanding of essential aspects of the solar atmosphere. We aim to determine the longitudinal magnetic field component (B_lon) of quiet Sun regions depending on their size. We estimated B_lon by applying the weak-field approximation (WFA) to high-spatial-resolution Ca II 854.2 nm data taken with the Swedish 1m Solar Telescope. Specifically, we analyzed the estimates inferred for different spectral ranges using the data at the original cadence and temporally integrated signals. The longitudinal magnetic field in each considered plasma structure correlates with its size. Using a spectral range restricted to the line core leads to chromospheric longitudinal fields varying from 50 G at the edges to 150-500 G at the center of the structure. These values increase as the spectral range widens due to the photospheric contribution. However, the difference between this contribution and the chromospheric one is not uniform for all structures. Small and medium-sized concentrations show a steeper height gradient in B_lon compared to their chromospheric values, so estimates for wider ranges are less trustworthy. Signal addition does not alleviate this situation as the height gradients in B_lon are consistent with time. Finally, despite the amplified noise levels that deconvolving processes may cause, data restored with the destretching technique show similar results, though are affected by smearing. We obtained B_lon estimates similar to those previously found, except for large concentrations and wide spectral ranges. In addition, we report a correlation between the height variation of B_lon compared to the chromospheric estimates and the concentration size. This correlation affects the difference between the photospheric and chromospheric magnetic flux values and the reliability of the estimates for wider spectral ranges.Comment: 14 pages, 14 figures. Accepted for publication in Astronomy & Astrophysics; abstract has been abridge

Magnetic solid-phase extraction based on poly 4-vinyl pyridine for HPLC-FLD analysis of naproxen in urine samples

Producción Científica: A magnetic solid phase extraction technique followed by liquid chromatography with a fluorescence detector for naproxen analysis in human urine samples was developed. The method includes the extraction of naproxen with a magnetic solid synthetized with magnetite and poly 4-vinylpriridine, followed by the magnetic separation of the solid phase and desorption of the analyte with methanol. Under optimal conditions, the linear range of the calibration curve was 0.05–0.60 μg L−1, with a limit of detection of 0.02 μg L−1. In all cases values of repeatability were lower than 5.0% with recoveries of 99.4 ± 1.3%. Precision and accuracy values are adequate for naproxen (Npx) analysis in urine samples

The chemical composition of the Orion star-forming region: II. Stars, gas, and dust: the abundance discrepancy conundrum

We re-examine the recombination/collisional emission line (RL/CEL) nebular abundance discrepancy problem in the light of recent high-quality abundance determinations in young stars in the Orion star-forming region. We re-evaluate the CEL and RL abundances of several elements in the Orion nebula and estimate the associated uncertainties, taking into account the uncertainties in the ionization correction factors for unseen ions. We estimate the amount of oxygen trapped in dust grains for several scenarios of dust formation. We compare the resulting gas+dust nebular abundances with the stellar abundances of a sample of 13 B-type stars from the Orion star-forming region (Ori\,OB1), analyzed in Papers I and III of this series. We find that the oxygen nebular abundance based on recombination lines agrees much better with the stellar abundances than the one derived from the collisionally excited lines. This result calls for further investigation. If the CEL/RL abundance discrepancy were caused by temperature fluctuations in the nebula, as argued by some authors, the same kind of discrepancy should be seen for the other elements, such as C, N and Ne, which is not what we find in the present study. Another problem is that with the RL abundances, the energy balance of the Orion nebula is not well understood. We make some suggestions concerning the next steps to undertake to solve this problem.Comment: 11 pages, 8 tables, 5 figures (To be published in A&A

Systemic administration of a fibroblast growth factor receptor 1 agonist rescues the cognitive deficit in aged socially isolated rats.

Social isolation predominantly occurs in elderly people and it is strongly associated with cognitive decline. However, the mechanisms that produce isolation-related cognitive dysfunction during aging remain unclear. Here, we evaluated the cognitive, electrophysiological, and morphological effects of short- (4 weeks) and long-term (12 weeks) social isolation in aged male Wistar rats. Long-term but not short-term social isolation increased the plasma corticosterone levels and impaired spatial memory in the Morris water maze. Moreover, isolated animals displayed dampened hippocampal long-term potentiation in vivo, both in the dentate gyrus (DG) and CA1, as well as a specific reduction in the volume of the stratum oriens and spine density in CA1. Interestingly, social isolation induced a transient increase in hippocampal basic fibroblast growth factor (FGF2), whereas fibroblast growth factor receptor 1 (FGFR1) levels only increased after long-term isolation. Importantly, subchronic systemic administration of FGL, a synthetic peptide that activates FGFR1, rescued spatial memory in long-term isolated rats. These findings provide new insights into the neurobiological mechanisms underlying the detrimental effects on memory of chronic social isolation in the aged.pre-print507 K