Segregation-induced grain boundary electrical potential in ionic oxide materials: A first principles model

A first principles continuum analytical model for cationic segregation to the grain boundaries in complex ceramic oxides is presented. The model permits one to determine the electric charge density and the segregation-induced electric potential profiles through the grain and can be extrapolated to the range of nanostructured grain sizes. The theoretical predictions are compared with existing data for yttria-stabilized tetragonal zirconia polycrystals. The implications for physical properties (mainly high temperature plasticity and hardening behaviour) are then discussed.Gobierno de España MAT2009-14351-C02-01, MAT2009-14351-C02-0

Obesity dependent metabolic signatures associated with nonalcoholic fatty liver disease progression

Our understanding of the mechanisms by which nonalcoholic fatty liver disease (NAFLD) progresses from simple steatosis to steatohepatitis (NASH) is still very limited. Despite the growing number of studies linking the disease with altered serum metabolite levels, an obstacle to the development of metabolome-based NAFLD predictors has been the lack of large cohort data from biopsy-proven patients matched for key metabolic features such as obesity. We studied 467 biopsied individuals with normal liver histology (n=90) or diagnosed with NAFLD (steatosis, n=246; NASH, n=131), randomly divided into estimation (80% of all patients) and validation (20% of all patients) groups. Qualitative determinations of 540 serum metabolite variables were performed using ultra-performance liquid chromatography coupled to mass spectrometry (UPLCMS). The metabolic profile was dependent on patient body-mass index (BMI), suggesting that the NAFLD pathogenesis mechanism may be quite different depending on an individual’s level of obesity. A BMI-stratified multivariate model based on the NAFLD serum metabolic profile was used to separate patients with and without NASH. The area under the receiver operating characteristic curve was 0.87 in the estimation and 0.85 in the validation group. The cutoff (0.54) corresponding to maximum average diagnostic accuracy (0.82) predicted NASH with a sensitivity of 0.71 and a specificity of 0.92 (negative/positive predictive values = 0.82/0.84). The present data, indicating that a BMI-dependent serum metabolic profile may be able to reliably distinguish NASH from steatosis patients, have significant implications for the development of NASH biomarkers and potential novel targets for therapeutic intervention

Impedancias dinámicas en zapatas rígidas y flexibles sobre medios viscoelásticos

Se presentan aplicaciones recientes del Método de los Elementos de Contorno al cálculo de impedancias de cimentaciones en terrenos viscoelásticos, haciendo especial hincapié en el tratamiento de medios estratificados para problemas con simetría de revolución y en la forma de tratar zapatas flexibles

Is the Fast Evolution Scenario for Virialized Compact Groups Really Compelling? The Role of a Dark Massive Group Halo

We report on results of N-body simulations aimed at testing the hypothesis that galaxies in X-ray emitting (i.e., virialized) Compact Groups are not tidally stripped when they are embedded in a common, massive, quiescent dark matter halo. To disentangle the effects of interactions from spurious effects due to an incorrect choice of the initial galaxy model configurations, these have been chosen to be tidally-limited King spheres, representing systems in quasi-equilibrium within the tidal field of the halo. The potential of the halo has been assumed to be frozen and the braking due to dynamical friction neglected. Our results confirm the hypothesis of low rates of tidal stripping and suggest a scenario for virialized Compact Group evolution in their quiescent phases with only very moderate tidally induced galaxy evolution can be generally expected. This implies the group stability, provided that the dynamical friction timescales in these systems are not much shorter than the Hubble time. We discuss briefly this possibility, in particular taking account of the similarity between the velocity dispersions of a typical virialized Compact Groups and the internal velocity dispersion of typical member galaxies. A number of puzzling observational data on Compact Groups can be easily explained in this framework. Other observations would be better understood as the result of enhanced merging activity in the proto-group environment, leading to virialized Compact Group formation through mergers of lower mass halos, as predicted by hierarchical scenarios of structure formation.Comment: 18 pages, 1 postscript file, 2 tables, to be published in ApJLet

Understanding Nanopore Window Distortions in the Reversible Molecular Valve Zeolite RHO

Molecular valves are becoming popular for potential biomedical applications. However, little is known concerning their performance in energy and environmental areas. Zeolite RHO shows unique pore deformations upon changes in hydration, cation siting, cation type, or temperature-pressure conditions. By varying the level of distortion of double eight-rings, it is possible to control the adsorption properties, which confer a molecular valve behavior to this material. We have employed interatomic potentials-based simulations to obtain a detailed atomistic view of the structural distortion mechanisms of zeolite RHO, in contrast with the averaged and space group restricted information provided by diffraction studies. We have modeled four aluminosilicate structures, containing Li$^+$, Na$^+$, K$^+$, Ca$^{2+}$, and Sr$^{2+}$ cations. The distortions of the three different zeolite rings are coupled, and the six- and eight-membered rings are largely flexible. A large dependence on the polarizing power of the extra-framework cations and with the loading of water has been found for the minimum aperture of the eight-membered rings that control the nanovalve effect. The calculated energy barriers for moving the cations across the eight-membered rings are very high, which explains the experimentally observed slow kinetics of the phase transition as well as the appearance of metastable phases

Shape and kinematics of elliptical galaxies: evolution due to merging at z < 1.5

[EN]Aims. We investigate the evolution in the shape and kinematics of elliptical galaxies in a cosmological framework. Methods. We identified relaxed, elliptical-like objects (ELOs) at redshifts z = 0, z = 0.5, z = 1 and z = 1.5 within a set of hydrodynamic, self-consistent simulations completed for a concordance cosmological model. Results. The population of elliptical systems that we analysed evolve systematically with time becoming rounder in general by z = 0 and also more velocity dispersion supported. We found that this is due primarily to major dry mergers where only a modest amount of angular momentum is involved in the merger event. Despite the general trend, in a significant number of cases the merger event involves a relatively high amount of specific angular momentum, which causes the system in general to acquire higher rotational support and/or a more oblate shape. These evolutionary patterns persist when we study our systems in projection, in simulating true observations, and thus should be evident in future observations.Peer reviewe

Contested discourses in social tourism:A relational political economy perspective

Social tourism initiatives often have economic as well as objectives, particularly national schemes such as the Spanish IMSERSO programme, designed to stimulate off-season tourism in mass coastal tourism destinations. Yet, there is little evidence of how such schemes responded to crises or that explores the effects on the tourism industry actors responsible for programme delivery. This article applies a relational political economy approach to assess the contested discourses surrounding the governance of the scheme. We examine the evolution of the IMSERSO programme longitudinally following the global financial crisis and up until the COVID-19 pandemic to assess the relational dynamics at play social tourism governance on destination stakeholders, outlining implications for social tourism policies internationally

Axonal guidance using biofunctionalized silk fibroin fibers manufactured using the SFS technique

After an injury, the central nervous system's limited regenerative capacity severely hampers the reconnection and functional recovery of affected nervous tissue, making it an arduous task. To address this critical issue, biomaterials have emerged as a promising solution for designing scaffolds that facilitate and guide the regenerative process. Leveraging prior research on regenerated silk fibroin fibers produced via the straining flow spinning (SFS) technique, this study aims to demonstrate that biofunctionalized SFS fibers offer superior guidance capabilities compared to non- functionalized fibers. The study reveals that neurons' axons exhibit a remarkable tendency to align with the fibers' paths, in contrast to the isotropic growth observed on conventional culture plates. Additionally, the guidance ability of these fibers can be further enhanced through the biofunctionalization of the material with adhesion peptides. Proving the exceptional guidance potential of these fibers opens up exciting possibilities for their application as implants in spinal cord injuries. They could serve as a core component of a therapeutic approach that facilitates the reconnection of injured spinal cord ends, holding promise for significantly improving treatment outcomes in such cases.This study was partially funded by the Ministerio de Ciencia e Innovación (PID2020-116403RB-I00; MCIN/AEI/10.13039/501100011033), Comunidad de Madrid (MINA-CM P2022-BMD-7236) and by the agreement between the Comunidad de Madrid (Spain) and the UPM through the REACT-UE funds of the European Regional Development Fund (ERDF), as a part of the response of the European Union to the SARS-CoV2 and COVID- 19 pandemic. It also has been financed by the UCM together with Banco Santander Scholarships (BOUC 11-23-2021; ref.: CT58/21-CT59/21)