1,364 research outputs found
On the absence of acylated anthocyanins in some wild grapevine accessions
Our current research is focused on the anthocyanin composition of female grape accessions, mostly Spanish, preserved at El Encín Germplasm Bank. In 2008, berries of 126 accessions were taken at maturity. After the extraction from grape skins, total anthocyans were determined by spectrophotometry, and the anthocyanin fingerprint of grapes by HPLC, considering the relative amount of 15 anthocyanins. Among those 126 accessions, 23 genotypes (18.25 %) did not present acylated anthocyanins. Thus, those 23 genotypes presented a characteristic anthocyanin fingerprint, similar at a certain extent to that presented by some Rhine basin and Italian grape cultivars, e.g., 'Pinot Noir' and 'Gaglioppo'. Nevertheless, the absence of acylated anthocyanins has not been described in any Spanish grape cultivar. The examination of the anthocyanin fingerprint of wild grapes without acylated anthocyanins reveals that the regulation of the anthocyanin biosynthesis may differ in various wild grape accessions.
Psychometric properties of the Brief-COPE for the evaluation of coping strategies in the Chilean population
The Brief-COPE is an abbreviated version of the COPE (Coping Orientation to Problems Experienced) Inventory, a self-report questionnaire developed to assess a broad range of coping responses. Currently, it is one of the best validated and most frequently used measures of coping strategies. The aim of this study was to validate a culturally appropriate Chilean version of the Brief-COPE, assess its psychometric properties and construct and congruent validity. The Spanish version of the Brief-COPE was administrated in a community sample of 1847 Chilean adult (60.4% women) exposed to a variety of stressful experiences. The factorial structure of the inventory was examined by comparing four different models found in previous studies in Latin American population. The results of confirmatory factor analyses revealed, as in the original studies, a 14-factor structure of the Brief-COPE. These dimensions showed adequate internal structure and consistency. The factorial invariance comparing women and men confirmed strict invariance. Additionally, the results showed significant correlation between some Brief-COPE scales, such as denial and substance use, with perceived stress and emotional support and active coping with subjective well-being. Overall, the present work offers a valid and reliable tool for assessing coping strategies in the Chilean population.This study was funded by CONICYT/FONDECYT (grant number 1180134) awarded to Felipe E. Garcia
Exploring Li-ion conductivity in cubic, tetragonal and mixed-phase Al-substituted Li7La3Zr2O12 using atomistic simulations and effective medium theory
Garnet Li7La3Zr2O12 (LLZO) is a promising solid electrolyte candidate for solid-state Li-ion batteries, but at room temperature it crystallizes in a poorly Li-ion conductive tetragonal phase. To this end, partial substitution of Li+ by Al3+ ions is an effective way to stabilize the highly conductive cubic phase at room temperature. Yet, fundamental aspects regarding this aliovalent substitution remain poorly understood. In this work, we use molecular dynamics and advanced hybrid Monte Carlo methods for systematic study of the room temperature Li-ion diffusion in tetragonal and cubic LLZO to shed light on important open questions. We find that Al substitution in tetrahedral sites of the tetragonal LLZO allows previously inaccessible sites to become available, which enhances Li-ion conductivity. In contrast, in the cubic phase Li-ion diffusion paths become blocked in the vicinity of Al ions, resulting in a decrease of Li-ion conductivity. Moreover, combining the conductivities of individual phases through an effective medium approximation allowed us to estimate the conductivities of cubic/tetragonal phase mixtures that are in good agreement with those reported in several experimental works. This suggests that phase coexistence (due to phase equilibrium or gradients in Al content within a sample) could have a significant impact on the conductivity of Al-substituted LLZO, particularly at low contents of Al3+. Overall, by making a thorough comparison with reported experimental data, the theoretical study and simulations of this work advance our current understanding of Li-ion mobility in Al-substituted LLZO garnets and might guide future in-depth characterization experiments of this relevant energy storage material.MINECO ENE2016-81020-R.
SGI/IZO-SGIker UPV/EHU.
the i2BASQUE academic network.
Barcelona Supercomputer Center (QCM-2016-450 3-0002)
Astronomical Site Ranking Based on Tropospheric Wind Statistics
We present comprehensive and reliable statistics of high altitude wind speeds
and the tropospheric flows at the location of five important astronomical
observatories. Statistical analysis exclusively of high altitude winds point to
La Palma as the most suitable site for adaptive optics, with a mean value of
22.13 m/s at the 200 mbar pressure level. La Silla is at the bottom of the
ranking, with the largest average value 200 mbar wind speed(33.35 m/s). We have
found a clear annual periodicity of high altitude winds for the five sites in
study. We have also explored the connection of high to low altitude atmospheric
winds as a first approach of the linear relationship between the average
velocity of the turbulence and high altitude winds (Sarazin & Tokovinin 2001).
We may conclude that high and low altitude winds show good linear relationships
at the five selected sites. The highest correlation coefficients correspond to
Paranal and San Pedro Martir, while La Palma and La Silla show similar high to
low altitude wind connection. Mauna Kea shows the smallest degree of
correlation, which suggests a weaker linear relationship. Our results support
the idea of high altitude winds as a parameter for rank astronomical sites in
terms of their suitability for adaptive optics, although we have no evidence
for adopting the same linear coefficient at different sites. The final value of
this linear coefficient at a particular site could drastically change the
interpretation of high altitude wind speeds as a direct parameter for site
characterization.Comment: 18 pages, 5 figures. Accepted in MNRA
Wind speed vertical distribution at Mt. Graham
The characterization of the wind speed vertical distribution V(h) is
fundamental for an astronomical site for many different reasons: (1) the wind
speed shear contributes to trigger optical turbulence in the whole troposphere,
(2) a few of the astroclimatic parameters such as the wavefront coherence time
(tau_0) depends directly on V(h), (3) the equivalent velocity V_0, controlling
the frequency at which the adaptive optics systems have to run to work
properly, depends on the vertical distribution of the wind speed and optical
turbulence. Also, a too strong wind speed near the ground can introduce
vibrations in the telescope structures. The wind speed at a precise pressure
(200 hPa) has frequently been used to retrieve indications concerning the tau_0
and the frequency limits imposed to all instrumentation based on adaptive
optics systems, but more recently it has been proved that V_200 (wind speed at
200 hPa) alone is not sufficient to provide exhaustive elements concerning this
topic and that the vertical distribution of the wind speed is necessary. In
this paper a complete characterization of the vertical distribution of wind
speed strength is done above Mt.Graham (Arizona, US), site of the Large
Binocular Telescope. We provide a climatological study extended over 10 years
using the operational analyses from the European Centre for Medium-Range
Weather Forecasts (ECMWF), we prove that this is representative of the wind
speed vertical distribution at Mt. Graham with exception of the boundary layer
and we prove that a mesoscale model can provide reliable nightly estimates of
V(h) above this astronomical site from the ground up to the top of the
atmosphere (~ 20 km).Comment: 12 pages, 9 figures (whereof 3 colour), accepted by MNRAS May 27,
201
At the Borderline of Shape Coexistence: Mo and Ru
Background: Even-even isotopes of Mo (Z=42) and Ru (Z=44) are nuclei close to the subshell closure at Z=40, where shape coexistence plays a significant role. As a result, their spectroscopic properties are expected to resemble those of Sr (Z=38) and Zr (Z=40). Exploring the evolution of these properties as they move away from the subshell closure is of great interest. Purpose: The purpose of this study is to reproduce the spectroscopic properties of even-even Mo961-4296-110 and Ru961-4498-114 isotopes and to determine the influence of shape coexistence. Method: We employed the interacting boson model with configuration mixing as the framework to calculate all the observables for Mo and Ru isotopes. We considered two types of configurations: 0-particle-0-hole and 2-particle-2-hole excitations. The model parameters were determined using a least-squares fitting to match the excitation energies and the B(E2) transition rates. Results: We obtained the excitation energies, B(E2) values, two-neutron separation energies, nuclear radii, and isotope shifts for the entire chain of isotopes. Our theoretical results show good agreement with experimental data. Furthermore, we conducted a detailed analysis of the wave functions and obtained the mean-field energy surfaces and the nuclear deformation parameter, β, for all considered isotopes. Conclusions: Our findings reveal that shape coexistence plays a significant role in Mo isotopes, with the crossing of intruder and regular configurations occurring at neutron number 60 (A=102), which induces a quantum phase transition. In contrast, in Ru isotopes, the intruder states have minimal influence, remaining at higher energies. However, at neutron number 60, also a quantum phase transition occurs in Ru isotopes.Junta de Andalucía P20-00617, P20-01247, US-1380840Ministerio de Ciencia e Innovación PID2019-104002GB-C21, PID2019-104002GB-C22, PID2020-114687GB-I00, PID2022-136228NB-C21, PID2022-136228NB-C22Ministerio de Economía y Competitividad UNHU-15CE-284
Atomistic Insight into Ion Transport and Conductivity in Ga/Al-Substituted LiLaZrO Solid Electrolytes
Garnet-structured LiLaZrO is a promising solid electrolyte for next-generation solid-state Li batteries. However, sufficiently fast Li-ion mobility required for battery applications only emerges at high temperatures, upon a phase transition to cubic structure. A well-known strategy to stabilize the cubic phase at room temperature relies on aliovalent substitution; in particular, the substitution of Li by Al and Ga ions. Yet, despite having the same formal charge, Ga substitution yields higher conductivities (~S/cm) than Al (~S/cm). The reason of such difference in ionic conductivity remains a mystery. Here we use molecular dynamic simulations and advanced sampling techniques to precisely unveil the atomistic origin of this phenomenon. Our results show that Li vacancies generated by Al and Ga substitution remain adjacent to Ga and Al ions, without contributing to the promotion of Li mobility. However, while Ga ions tend to allow limited Li diffusion within their immediate surroundings, the less repulsive interactions associated with Al ions lead to a complete blockage of neighboring Li diffusion paths. This effect is magnified at lower temperatures, and explains the higher conductivities observed for Ga-substituted systems. Overall this study provides a valuable insight into the fundamental ion transport mechanism in the bulk of Ga/Al-substituted LiLaZrO and paves the way for rationalizing aliovalent substitution design strategies for enhancing ionic transport in these materials.ENE2016-81020-R (MINECO
Multiscale Modelling and Simulation of Advanced Battery Materials
Development of efficient strategies for the rational design of materials involved in the production and storage of renewable energy is essential for accelerating the transition to a low-carbon economy. To contribute to this goal, we propose a novel workflow for the assessment and optimization of battery materials. The approach effectively combines quantum and atomistic modelling/simulations, enhanced by efficient sampling, Bayesian parameterization, and experimental information. It is implemented to study prospective materials for lithium and sodium batteries
Conventional Space-Vector Modulation Techniques versus the Single-Phase Modulator for Multilevel Converters
Space-vector modulation is a well-suited technique
to be applied to multilevel converters and is an important
research focus in the last 25 years. Recently, a single-phase
multilevel modulator has been introduced showing its conceptual
simplicity and its very low computational cost. In this paper,
some of the most conventional multilevel space-vector modulation
techniques have been chosen to compare their results with those
obtained with single-phase multilevel modulators. The obtained
results demonstrate that the single-phase multilevel modulators
applied to each phase are equivalent with the chosen wellknown
multilevel space-vector modulation techniques. In this
way, single-phase multilevel modulators can be applied to a
converter with any number of levels and phases avoiding the
use of conceptually and mathematically complex space-vector
modulation strategies. Analytical calculations and experimental
results are shown validating the proposed concepts
Plasma impact on diagnostic mirrors in JET
Metallic mirrors will be essential components of all optical systems for plasma diagnosis in ITER. This contribution provides a comprehensive account on plasma impact on diagnostic mirrors in JET with the ITER-Like Wall. Specimens from the First Mirror Test and the lithium-beam diagnostic have been studied by spectrophotometry, ion beam analysis and electron microscopy. Test mirrors made of molybdenum were retrieved from the main chamber and the divertor after exposure to the 2013–2014 experimen- tal campaign. In the main chamber, only mirrors located at the entrance of the carrier lost reflectivity (Be deposition), while those located deeper in the carrier were only slightly affected. The performance of mirrors in the JET divertor was strongly degraded by deposition of beryllium, tungsten and other species. Mirrors from the lithium-beam diagnostic have been studied for the first time. Gold coatings were severely damaged by intense arcing. As a consequence, material mixing of the gold layer with the stainless steel substrate occurred. Total reflectivity dropped from over 90% to less than 60%, i.e. to the level typical for stainless steel.EURATOM 63305
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