Non-ergodic states induced by impurity levels in quantum spin chains

The semi-infinite XY spin chain with an impurity at the boundary has been chosen as a prototype of interacting many-body systems to test for non-ergodic behavior. The model is exactly solvable in analytic way in the thermodynamic limit, where energy eigenstates and the spectrum are obtained in closed form. In addition of a continuous band, localized states may split off from the continuum, for some values of the impurity parameters. In the next step, after the preparation of an arbitrary non-equilibrium state, we observe the time evolution of the site magnetization. Relaxation properties are described by the long-time behavior, which is estimated using the stationary phase method. Absence of localized states defines an ergodic region in parameter space, where the system relaxes to a homogeneous magnetization. Out of this region, impurity levels split from the band, and localization phenomena may lead to non-ergodicity.Comment: 10 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:1703.0344

Cosmological Bianchi Class A models in S\'aez-Ballester theory

We use the S\'aez-Ballester (SB) theory on anisotropic Bianchi Class A cosmological model, with barotropic fluid and cosmological constant, using the Hamilton or Hamilton-Jacobi approach. Contrary to claims in the specialized literature, it is shown that the S\'aez-Ballester theory cannot provide a realistic solution to the dark matter problem of Cosmology for the dust epoch, without a fine tunning because the contribution of the scalar field in this theory is equivalent to a stiff fluid (as can be seen from the energy--momentum tensor for the scalar field), that evolves in a different way as the dust component. To have similar contributions of the scalar component and the dust component implies that their past values were fine tunned. So, we reinterpreting this null result as an indication that dark matter plays a central role in the formation of structures and galaxy evolution, having measureable effects in the cosmic microwave bound radiation, and than this formalism yield to this epoch as primigenius results. We do the mention that this formalism was used recently in the so called K-essence theory applied to dark energy problem, in place to the dark matter problem. Also, we include a quantization procedure of the theory which can be simplified by reinterpreting the theory in the Einstein frame, where the scalar field can be interpreted as part of the matter content of the theory, and exact solutions to the Wheeler-DeWitt equation are found, employing the Bianchi Class A cosmological models.Comment: 24 pages; ISBN: 978-953-307-626-3, InTec

Patrones de diversidad alfa, beta y gama de la herpetofauna de las tierras bajas y valles adyacentes del Pacífico de México

The latitudinal distribution patterns of alpha, beta and gamma diversity of reptiles, amphibians and herpetofauna were analyzed using individual binary models of potential distribution for 301 species predicted by ecological modelling for a grid of 9,932 quadrants of ~25 km2 each. We arranged quadrants in 312 latitudinal bands in which alpha, beta and gamma values were determined. Latitudinal trends of all scales of diversity were similar in all groups. Alpha and gamma responded inversely to latitude whereas beta showed a high latitudinal fluctuation due to the high number of endemic species. Alpha and gamma showed a strong correlation in all groups. Beta diversity is an important component of the herpetofauna distribution patterns as a continuous source of species diversity throughout the region. Key words: Latitudinal distribution pattern, Diversity scales, Herpetofauna, Western Mexico.Se analizaron los patrones de distribución latitudinales de la diversidad alfa, beta y gama de los reptiles, anfibios y herpetofauna utilizando modelos binarios individuales de distribución potencial de 301 especies predichas mediante un modelo ecológico para una cuadrícula de 9.932 cuadrantes de aproximadamente 25 km2 cada uno. Se organizaron los cuadrantes en 312 bandas latitudinales para las cuales se determinaron los valores de alfa, beta y gama. Las tendencias latitudinales de todas las escalas de diversidad eran similares en todos los grupos. Alfa y gama respondieron inversamente a la latitud mientras que beta registró una gran fluctuación latitudinal debida al alto número de especies endémicas. Alfa y gama mostraron una fuerte correlación en todos los grupos. La diversidad beta es un componente importante de los patrones de distribución de la herpetofauna como una fuente constante de diversidad de especies a lo largo de la región. Palabras clave: Patrón latitudinal de distribución, Escalas de diversidad, Herpetofauna, Oeste de México

Raman microprobe characterization of electrodeposited S-rich CuIn(S,Se)2 for photovoltaic applications: Microstructural analysis

This article reports a detailed Raman scattering and microstructural characterization of S-rich CuIn(S,Se)2 absorbers produced by electrodeposition of nanocrystalline CuInSe2 precursors and subsequent reactive annealing under sulfurizing conditions. Surface and in-depth resolved Raman microprobe measurements have been correlated with the analysis of the layers by optical and scanning electron microscopy, x-ray diffraction, and in-depth Auger electron spectroscopy. This has allowed corroboration of the high crystalline quality of the sulfurized layers. The sulfurizing conditions used also lead to the formation of a relatively thick MoS2 intermediate layer between the absorber and the Mo back contact. The analysis of the absorbers has also allowed identification of the presence of In-rich secondary phases, which are likely related to the coexistence in the electrodeposited precursors of ordered vacancy compound domains with the main chalcopyrite phase, in spite of the Cu-rich conditions used in the growth. This points out the higher complexity of the electrodeposition and sulfurization processes in relation to those based in vacuum deposition techniques

Phenolic-rich extracts from avocado fruit residues as functional food ingredients with antioxidant and antiproliferative properties

In this study, the total phenolic compounds content and profile, the nutritional value, the antioxidant and antiproliferative activities of avocado peel, seed coat, and seed extracts were characterized. Additionally, an in-silico analysis was performed to identify the phenolic compounds with the highest intestinal absorption and Caco-2 permeability. The avocado peel extract possessed the highest content of phenolic compounds (309.95 ± 25.33 mMol GA/100 g of extract) and the lowest effective concentration (EC50) against DPPH and ABTS radicals (72.64 ± 10.70 and 181.68 ± 18.47, respectively). On the other hand, the peel and seed coat extracts had the lowest energy densities (226.06 ± 0.06 kcal/100g and 219.62 ± 0.49 kcal/100g, respectively). Regarding the antiproliferative activity, the avocado peel extract (180 ± 40 µg/mL) showed the lowest inhibitory concentration (IC50), followed by the seed (200 ± 21 µg/mL) and seed coat (340 ± 32 µg/mL) extracts. The IC50 of the extracts induced apoptosis in Caco-2 cells at the early and late stages. According to the in-silico analysis, these results could be related to the higher Caco-2 permeability to hy-droxysalidroside, salidroside, sakuranetin, and luteolin. Therefore, this study provides new insights regarding the potential use of these extracts as functional ingredients with antioxidant and antiproliferative properties and as medicinal agents in diseases related to oxidative stress such as cancer. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Adsorción de contaminantes farmacéuticos sobre monolitos de carbón activo

La eliminación de contaminantes emergentes de origen farmacéutico mediante adsorción está adquiriendo una gran importancia debido a que muchos de ellos poseen una alta estabilidad química y térmica, y son biológicamente activos. Muchos de estos contaminantes han sido detectados en aguas superficiales a niveles cercanos a los 100g/L [1]. Debido a la baja eficiencia de los sistemas de depuración de aguas residuales sobre la eliminación de estos contaminantes, es necesario el uso de sistemas avanzados, como la adsorción, para conseguir eliminar estos contaminantes. En este trabajo se muestran los resultados obtenidos al realizar estudios termodinámicos y cinéticos de la adsorción de productos farmacéuticos a bajas concentraciones (carbamazepina y paracetamol <20 mg/L) sobre distintos materiales monolíticos obtenidos mediante activación química con H3PO4.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Carbon-based nanomaterials for gold (III) recovery: kinetics and loading investigations

Currently, the development of different smart technology to recover or eliminate strategic or toxic metals from liquid effluent is constant. Among the different process developed to the treatment of liquid effluents bearing these types of metallic elements, include chemical or electrochemical precipitation, membrane based technology, ion exchange and adsorption. Adsorption is a high efficiency, cost-effectiveness and easily handing method to recover pollutants or strategic metals. Nowadays a research challenge is the development of new adsorbents. Among nanomaterials, carbon nanomaterials have adequate properties to be used as metal adsorbent. On the other hand gold is one of the most precious elements in the world. The price in 2015 of this strategic metal is 1.376 $/kg. Besides its uses in jewellery it is highly used in different industries, so it is important the gold recovery from liquid effluents generated from these various industries. The adsorption method is a way to treat these types of effluents, characterized for their low gold concentration. The aim of this research was to optimize various operational parameters, and thus obtain efficient carbon nanotubes processing for gold (III)-bearing effluents. The adsorption of gold (III) by carbon nanofibers (CNF), carbon multiwalled (MWCN) and carbon multiwalled with carboxyl group (MWCN_ox) systems were investigated. The experimental parameters which may influence gold adsorption were investigated, i.e. stirring speed of the aqueous solutions, adsorbent dosage, acid concentration, temperature etc. Figure 1 shows the effect of the acid concentration on the Au(III) adsorption to the three adsorbent. It can be seen that the adsorption Au(III) decreases with the increase of HCl concentration. Probalby it is due the existence of other gold species, such as HAuCl4, at the higher hydrochloric solution against the presence of the predominant AuCl4- species in the more dilute HCl solutions which are more adsorbable than the gold-acid form. SEM studies of gold loaded carbon nanomaterials show on the surface dark particles, Figure 2. The EDS of the dark particles show two peaks for Lα(9.7 keV) and Mα (2.1 keV) characteristic of metallic gold. Probably this reduction occurs on the carbon surface, related with the metal reduction. The isotherm and kinetic studies of the carbon nanomaterial-Au(III) system show a different behavior in function of the carbon nanomaterial used as adsorbent. The experimental data obtained using the MWCNT and CNF fit better to a pseudo second order equation and an isotherm Freundlich model. The three carbon nanomaterials, appeared to be a promising material for recovery of Au(III) from this type of acid solutions in the optimal experimental for each one of them condition.Peer reviewe

Macromicetes de la comarca del Berguedá (Barcelona)

Se da cuenta de ciento cuarenta y ocho especies de macromicetes recolectadas en el transcurso de una serie de excursiones de estudio, realizadas por los autores entre los años 1974 al 1977, por diversas localidades de la comarca del Berguedá (Barcelona).Numerosas especies entre las indicadas fueron recolectadas en varias ocasiones, lo que permitió apreciar detalles de su comportamiento autoecológico.En todos los casos hemos pretendido confirmar las determinaciones taxonómicas utilizando los medios reseñados en la Bibliografia. De cada especie se dispone de su ficha de estudio, con los detalles apreciados al realizar la determinanción, pese a ello no hemos considerado adecuado dar descripciones por no hacer más extenso el presente trabajo.We remark the determinations of a hundred and forty eight species of Macromycets collected the year 1974 to the 1977, mainly in Berguedá district (Barcelona).Most of them could be studied more than once. We tried to confirm the determinations using the last specialized works