Stannites – a new promising class of durable electrocatalysts for efficient water oxidation

The oxygen evolution reaction (OER) through water oxidation is a key process for multiple energy storage technologies required for a sustainable energy economy such as the formation of the fuel hydrogen from water and electricity, or metal‐air batteries. Herein, we investigate the suitability of Cu2FeSnS4 for the OER and demonstrate its superiority over iron sulfide, iron (oxy)hydroxides and benchmark noble‐metal catalysts in alkaline media. Electrodeposited Cu2FeSnS4 yields the current densities of 10 and 1000 mA/cm2 at overpotentials of merely 228 and 330 mV, respectively. State‐of‐the‐art analytical methods are applied before and after electrocatalysis to uncover the fate of the Cu2FeSnS4 precatalyst under OER conditions and to deduce structure‐activity relationships. Cu2FeSnS4 is the first compound reported for OER among the broad class of stannite structure type materials containing multiple members with highly active earth‐abundant transition‐metals for OER.DFG, 390540038, EXC 2008: Cluster of Excellence UniSysCatTU Berlin, Open-Access-Mittel - 201

Heavy neutral leptons from kaons in effective field theory

In the framework of the low-energy effective theory containing in addition to the Standard Model fields heavy neutral leptons (HNLs), we compute the decay rates of neutral and charged kaons into HNLs. We consider both lepton-number-conserving and lepton-number-violating four-fermion operators, taking into account also the contribution of active-heavy neutrino mixing. Assuming that the produced HNLs are long-lived, we perform simulations and calculate the sensitivities of future long-lived-particle (LLP) detectors at the high-luminosity LHC to the considered scenario. When applicable, we also recast the existing bounds on the minimal mixing case obtained by NA62, T2K, and PS191. Our findings show that for some of the effective operators considered the future LLP detectors, in particular, MATHUSLA and ANUBIS, will probe (i) new parts of the parameter space spanned by HNL mass and active-heavy neutrino mixing, and (ii) new-physics scales in excess of $2000$ TeV.Comment: Result figures have been updated and text was changed accordingl

Combination of Selective Etching and Impregnation toward Hollow Mesoporous Bioactive Glass Nanoparticles

In this study, binary SiO2-CaO hollow mesoporous bioactive glass nanoparticles (HMBGNs) are prepared by combing selective etching and impregnation strategies. Spherical silica particles (SiO2 NPs) are used as hard cores to assemble cetyltrimethylammonium bromide (CTAB)/silica shells, which are later removed by selective etching to generate a hollow structure. After the removal of CTAB by calcination, the mesoporous shell of particles is formed. Calcium (Ca) is incorporated into the particles using impregnation by soaking the etched SiO2 NPs in calcium nitrate aqueous solution. The amount of incorporated Ca is tailorable by controlling the ratio of SiO2 NPs:calcium nitrate in the soaking solution. The produced HMBGNs are bioactive, as indicated by the rapid formation of hydroxyapatite on their surfaces after immersion in simulated body fluid. In a direct culture with MC3T3-E1 cells, HMBGNs were shown to exhibit concentration-dependent cytotoxicity and can stimulate osteogenic differentiation of MC3T3-E1 cells at concentrations of 1, 0.5, and 0.25 mg/mL. Our results indicate that the combination of selective etching and impregnation is a feasible approach to produce hierarchical HMBGNs. The produced hollow particles have potential in drug delivery and bone tissue regeneration applications, and should be further investigated in detailed in vitro and in vivo studies.European Union’s Horizon 2020 research and innovation program 685872-MOZAR

Long-lived heavy neutral leptons from mesons in effective field theory

In the framework of the low-energy effective field theory of the Standard Model extended with heavy neutral leptons (HNLs), we calculate the production rates of HNLs from meson decays triggered by dimension-six operators. We consider both lepton-number-conserving and lepton-number-violating four-fermion operators involving either a pair of HNLs or a single HNL. Assuming that HNLs are long-lived, we perform simulations and investigate the reach of the proposed far detectors at the high-luminosity LHC to (i) active-heavy neutrino mixing and (ii) the Wilson coefficients associated with the effective operators, for HNL masses below the mass of the $B$-meson. We further convert the latter to the associated new-physics scales. Our results show that scales in excess of hundreds of TeV and the active-heavy mixing squared as small as $10^{-15}$ can be probed by these experiments.Comment: Comments and references added; results unchanged; matches version accepted for publication in JHE

Non-adiabatic effects during the dissociative adsorption of O2 at Ag(111)? A first-principles divide and conquer study

We study the gas-surface dynamics of O2 at Ag(111) with the particular objective to unravel whether electronic non-adiabatic effects are contributing to the experimentally established inertness of the surface with respect to oxygen uptake. We employ a first-principles divide and conquer approach based on an extensive density-functional theory mapping of the adiabatic potential energy surface (PES) along the six O2 molecular degrees of freedom. Neural networks are subsequently used to interpolate this grid data to a continuous representation. The low computational cost with which forces are available from this PES representation allows then for a sufficiently large number of molecular dynamics trajectories to quantitatively determine the very low initial dissociative sticking coefficient at this surface. Already these adiabatic calculations yield dissociation probabilities close to the scattered experimental data. Our analysis shows that this low reactivity is governed by large energy barriers in excess of 1.1 eV very close to the surface. Unfortunately, these adiabatic PES characteristics render the dissociative sticking a rather insensitive quantity with respect to a potential spin or charge non-adiabaticity in the O2-Ag(111) interaction. We correspondingly attribute the remaining deviations between the computed and measured dissociation probabilities primarily to unresolved experimental issues with respect to surface imperfections.Comment: 18 pages including 6 figure

Planeamiento dinámico de la expansión de los sistemas de transmisión usando algoritmos meméticos

El objetivo del Planeamiento Dinámico de la Expansión de los Sistemas de Transmisión (PDEST) es determinar qué infraestructura eléctrica, en qué lugar y en qué momento debe ser agregada a un sistema eléctrico de potencia dentro de un horizonte de tiempo determinado. La adición de nuevos componentes al sistema procura satisfacer el crecimiento de la demanda, y cumplir con parámetros de eficiencia, calidad de servicio, confiabilidad y economía, dentro del horizonte de planeamiento. En este trabajo de investigación se propone e implementa un método de solución usando una técnica basada en Algoritmos Meméticos, los cuales resuelven el problema del PDEST combinando técnicas de solución basadas en población y búsqueda local. El algoritmo propuesto combina la técnica de Enjambre de Partículas (PSO) y la técnica de búsqueda local Hill Climbing. Los sistemas de prueba para obtener los resultados fueron los sistemas Garver y el IEEE de 24 nodos. Los escenarios de prueba para estos sistemas fueron con y sin redespacho.The objective of Dynamic Transmission Expansion Planning (DTEP) is to determine what electrical infrastructure, where and when it should be added to a power system within a given time horizon. The addition of new components to the system seeks to meet the growth in demand, and to comply with parameters of efficiency, quality of service, reliability and economy, within the planning horizon. In this research work, a solution method is proposed and implemented using a technique based on Memetic Algorithms, which solves the DTEP problem by combining solution techniques based on population and local search. The proposed algorithm combines the Particle Swarm Optimization (PSO) technique and Hill Climbing local search technique. The test systems to obtain the results were the Garver and the 24-node IEEE systems. The test scenarios for these systems were with and without redispatch.Ingeniero EléctricoCuenc

El rol de género como fundamento humanista de la formación para la ciudadanía

Objetivo. Analizar desde una mirada crítica la comprensión social que tiene el ámbito educativo respecto al género. Se presentan algunas perspectivas de comprensión humanista y el alcance político de esta categoría constitutiva de lo humano. Método. Ejercicio etnográfico y análisis crítico desde el enfoque humanista de las capacidades desarrollado por Martha Nussbaum. Resultados. El género constituye un elemento fundante de la identidad de la personal, no sólo de algunos grupos minoritarios sino de la sociedad en general, lo cual configura su alcance político en la constitución de la ciudadanía incluyente

Transparent LiOH-doped magnesium aluminate spinel produced by spark plasma sintering: Effects of heating rate and dopant concentration

The effects of LiOH doping of magnesium aluminate spinel powders and various Spark Plasma Sintering (SPS) schedules on densification behavior and final transparency of polycrystalline magnesium aluminate spinel were studied. Two commercial magnesium aluminate spinel powders, with different specific surface areas, were doped with up to 0.6 wt% of LiOH and consolidated using SPS with slow (2.75 °C/min) and fast (100 °C/min) heating rates. The slow heating rate was optimal for undoped magnesium aluminate spinel (LiOH-free) with the best real in-line transmittance (RIT) of 84.8% (measured at 633 nm on a disc 0.8 mm thick). For the magnesium aluminate spinel doped with 0.3 wt% of LiOH, the fast heating rate was beneficial, and an RIT of 76.5% was achieved. μ-Raman analysis confirmed that the addition of LiOH suppressed carbon contamination

Use of the barbed suture (V-loc ™) in the laparoscopic gastroyeyunal by-pass: experience in 354 intervened patients

Introduction: The barbed suture is a device developed in recent years to simplify the intracorporeal suture and improve safety in laparoscopic surgery. We describe our experience in the use of V-Loc ™ in Laparoscopic Roux-en-Y gastric bypass (LRYGB). This suture has been used for the closure of enterotomy after mechanical lateral J-J anastomosis (bile limb-alimentary limb), for the closure of the mesenteric defect and, occasionally, for the closure of the Petersen space. It is presented as an observational study from 2012 to 2019 with the results of 354 patients undergoing bypass. Objective: To evaluate the safety of this type of suture by demonstrating the absence of leakage, bleeding, stenosis or other complications associated with its use in bariatric laparoscopic surgery. Material and Methods: Between June 2012 and July 2019, a total of 746 bariatric surgeries were performed in our unit. Of all of them, 354 corresponded to bypass in which barbed suture (V-Loc ™ 3-0 6 ”15cm, non-absorbable Polybutester (PBT), Covidien ™) was used in different phases of surgery. The results of the series are analyzed retrospectively. Results: Of the 354 surgical procedures performed, only one case underwent urgent laparoscopic examination within the next 24 hours after surgery due to a defect in the closure of enterotomy in the J-J anastomosis. There were no short-term or longterm postoperative complications in the rest of the patients operated on. Conclusion: The use of V-Loc ™ is safe, effective and reproducible applied to bariatric surgery, especially LGYB

Complexity-entropy causality plane: a useful approach for distinguishing songs

Nowadays we are often faced with huge databases resulting from the rapid growth of data storage technologies. This is particularly true when dealing with music databases. In this context, it is essential to have techniques and tools able to discriminate properties from these massive sets. In this work, we report on a statistical analysis of more than ten thousand songs aiming to obtain a complexity hierarchy. Our approach is based on the estimation of the permutation entropy combined with an intensive complexity measure, building up the complexity-entropy causality plane. The results obtained indicate that this representation space is very promising to discriminate songs as well as to allow a relative quantitative comparison among songs. Additionally, we believe that the here-reported method may be applied in practical situations since it is simple, robust and has a fast numerical implementation.Comment: Accepted for publication in Physica