Electrochemical behavior of lanthanum and yttrium ions in two molten chlorides with different oxoacidic properties: The eutectic LiCl-KCl and the equimolar mixture CaCl2-NaCl

The electrochemical behavior of LaCl3 and YCl3 was studied in two molten chloride mixtures with different oxoacidic properties, the eutectic LiCl-KCl and the equimolar CaCl2-NaCl melt at different temperatures. The stable oxidation states of both elements have been found to be (III) and (0) in both melts, and it was found that both La(III) and Y(III) cations were less solvated by the chloride ions in the calcium-based melt, which was explained by the stability of CaCl4 2- ions in that melt. Transient electrochemical techniques, such as cyclic voltammetry, chronopotentiometry and chronoamperometry were used in order to study the reaction mechanism and the transport parameters of electro active species at a tungsten electrode. The results showed that in the eutectic LiCl-KCl, the electro crystallization of lanthanum and yttrium seems to be the controlling electrochemical step while in CaCl2-NaCl this phenomenon has not been observed. That was explained in terms of the differences in the physicochemical properties of the systems, especially interfacial tensions. In the eutectic LiCl-KCl chronoamperometric studies indicated instantaneous and three dimensional nucleation and crystal growth of lanthanum and yttrium whatever the applied over potential of the rare earth metal is, whereas in the equimolar mixture CaCl2-NaCl, the corresponding electrochemical exchanges were found to be quasi-reversible, and the values of the kinetic parameters, K0 and α,were obtained for both reactions. Mass transport towards the electrode is a simple diffusion process, and the diffusion coefficients have been calculated. The validity of the Arrhenius law was also verified by plotting the variation of the logarithm of the diffusion coefficient versus 1/T

Vertex Cover Kernelization Revisited: Upper and Lower Bounds for a Refined Parameter

An important result in the study of polynomial-time preprocessing shows that there is an algorithm which given an instance (G,k) of Vertex Cover outputs an equivalent instance (G',k') in polynomial time with the guarantee that G' has at most 2k' vertices (and thus O((k')^2) edges) with k' <= k. Using the terminology of parameterized complexity we say that k-Vertex Cover has a kernel with 2k vertices. There is complexity-theoretic evidence that both 2k vertices and Theta(k^2) edges are optimal for the kernel size. In this paper we consider the Vertex Cover problem with a different parameter, the size fvs(G) of a minimum feedback vertex set for G. This refined parameter is structurally smaller than the parameter k associated to the vertex covering number vc(G) since fvs(G) <= vc(G) and the difference can be arbitrarily large. We give a kernel for Vertex Cover with a number of vertices that is cubic in fvs(G): an instance (G,X,k) of Vertex Cover, where X is a feedback vertex set for G, can be transformed in polynomial time into an equivalent instance (G',X',k') such that |V(G')| <= 2k and |V(G')| <= O(|X'|^3). A similar result holds when the feedback vertex set X is not given along with the input. In sharp contrast we show that the Weighted Vertex Cover problem does not have a polynomial kernel when parameterized by the cardinality of a given vertex cover of the graph unless NP is in coNP/poly and the polynomial hierarchy collapses to the third level.Comment: Published in "Theory of Computing Systems" as an Open Access publicatio

Confinement Effects in Antiferromagnets

Phase equilibrium in confined Ising antiferromagnets was studied as a function of the coupling (v) and a magnetic field (h) at the surfaces, in the presence of an external field H. The ground state properties were calculated exactly for symmetric boundary conditions and nearest-neighbor interactions, and a full zero-temperature phase diagram in the plane v-h was obtained for films with symmetry-preserving surface orientations. The ground-state analysis was extended to the H-T plane using a cluster-variation free energy. The study of the finite-T properties (as a function of v and h) reveals the close interdependence between the surface and finite-size effects and, together with the ground-state phase diagram, provides an integral picture of the confinement in anisotropic antiferromagnets with surfaces that preserve the symmetry of the order parameter.Comment: 10 pages, 8 figures, Accepted in Phys. Rev.

Constituents of Quercus eduardii leaf infusion: Their interaction with gut microbiota communities and therapeutic role in colorectal cancer.

The infusion of Q. eduardii leaves has been used ancestrally for medicinal purposes. We investigated the effect of Q. eduardii infusion intake on inflammatory and oncogenic biomarkers in animals induced to have colorectal cancer with DMH. We also investigated its influence on the microbiota, establishing the main microbial metabolites in the intestinal content of the experimental animals. The microbial metabolites associated with greater anti-inflammatory and anticarcinogenic activity were 3́-hydroxyphenylacetic acid (3HPA) and €-3-(3,4,5-trimethoxyphenyl) prop-2-enoic acid (TMCA). Finally, the intake of the Q. eduardii infusion significantly increased the abundance of the Erysipelotrichaceae and Lachnospiraceae families, that seems to have a great influence on the antitumor responses detected in the study.post-print4648 K

Weight-length relationships, weight conversion factors and condition factor trends for two stocks of black anglerfish (Lophius budegassa) in southern Bay of Biscay, Galician waters and northern Atlantic areas from a decade

The weight-length relationship has a wide application in fish biology and fisheries management, such as for predicting weight from length data, or for the calculation of production and biomass of a fish stock. Weight-length relationship, weight conversion factors and condition factor are presented from a decade (2006 to 2015) for both stocks of black anglerfish (Lophius budegassa) in southern Bay of Biscay and Galician waters (ICES Div. VIIIc-IXa, southern stock) and in Celtic Seas (ICES Div. VIIb,c,h,j,k, northern stock). A total of 2035 and 1263 specimens were sampled respectively in each stock from commercial landings and research surveys. Total length [Lt (cm)], total weight [Wt (g)], “commercial” weight (gutted with liver) [Wgl (g)] and “scientific” weight (gutted without liver) [Wg (g)] were obtained. The weight-length relationships for the combined sexes were: Lt = 0.020 Wt2.916; Lt = 0.017 Wgl2.929; Lt = 0.017 Wg2.922 in Div. VIIIc-IXa, and Lt = 0.025 Wt2.841; Lt = 0.013 Wgl2.984; Lt = 0.013 Wg2.971 in Div. VIIb,c,h,j,k. These updated values can be used in the annual assessment of the state of both stocks in the ICES working group, replacing those previous estimated more than a decade ago. The conversion factor (total weight - gutted weight) here estimated is also useful in fisheries management due to the commercial landings of this species are available in gutted weight. The evolution of the condition factor along the year, indicator of nutritional status evolution, is estimated and can be a proxy for estimating the spawning season. Its evolution is studied throughout the year for immature and mature individuals of each sex. The results are similar to the previously estimated in other studies

Determinacion de zonas isotermicas y seleccion de estaciones meteorologicas representativas en Aragon como base para la estimacion del impacto del cambio climatico sobre la posible relacion entre mortalidad y temperatura.

Fundamento: En regiones extensas y diversificadas, como Aragón, se cree la necesidad de dividirlas en áreas en función de las variables atmosféricas disponibles, para seleccionar una estación meteorológica representativa. El objeto de este artículo es determinar la existencia de regiones isotérmicas y seleccionar las estaciones representativas con el fin de estudiar la correlación entre variables de temperatura y mortalidad diaria. Métodos: Se seleccionaron datos diarios de temperatura máxima y mínima para el periodo comprendido entre enero de 1987 y diciembre de 2006. Para determinar las zonas isotérmicas se realizó un análisis de conglomerados jerárquicos y un análisis factorial discriminante, así como un tratamiento previo de datos de relleno de lagunas y detección de heterogeneidades en las series climáticas. Se analizaron datos de 93 estaciones (44 en Huesca, 15 en Teruel y 34 en Zaragoza). Resultados: De los resultados del análisis para la regionalización de Aragón extrajimos que un solo factor explica la varianza de cada serie. En temperaturas máximas ese único factor explicó el 93,43% de la varianza y la estación que representó un mayor factor de correlación fue Huesca-Monflorite (correlación=0,984). Para temperaturas mínimas un único factor explicó el 90,88% de la varianza, siendo la estación con mayor factor de correlación Pallaruelo de Monegros (correlación=0,976). Conclusiones: Se consideró que Aragón es una única región isotérmica con una única estación representativa de la variabilidad de las temperaturas, Zaragoza-Aeropuerto, con una correlación en temperaturas máximas de 0,980 y en mínimas de 0,974. Background: In extensive and diversified regions, such as Aragon, it is believed the need to divide them into areas in terms of the available atmospheric variables with a view to select a representative weather station. The objective of this study was to determine the existence of isothermal regions and select representative stations for Aragon in order to carry out further study on the correlation between variables of temperature and daily mortality. Methods: Daily data on maximum and minimum temperature for the period between January 1987 and December 2006 was selected. In order to determine the isothermal areas a cluster analysis and a discriminate factor analysis were carried out along with a data pretreatment of filled gaps and detection of inhomogeneities in the climatic series. We analyzed data from 93 stations (44 in Huesca, 15 in Teruel and 34 in Zaragoza). Results: The results of the analysis for the regionalization of Aragon lead us to conclude that a unique factor explains the variance of each series; at high temperatures one factor explains 93.43% of the variance and the station with the highest correlation factor is Monflorite-Huesca (correlation = 0.984). At low temperatures one factor explains 90.88% of the variance, with Monegros-Pallaruelo being the station that presents the greatest correlation factor (correlation = 0.976). Conclusions: It was felt that Aragon was a unique isothermal region with one unique representative station of the temperature variability, Zaragoza-Airport with a correlation of 0.980 in maximum temperatures and 0.974 minimum

Application of Park's power components to the differential protection of three-phase transformers

This paper presents a new scheme for power transformers differential protection, in which the concept of the Park's instantaneous differential powers is introduced. The proposed method is able to detect winding insulation failures and to distinguish them from magnetizing inrush current transients. Experimental and simulation results are presented and discussed

Radiological Study of Water for Human Use and Consumption in Rural Areas of the Central Zone of the State of Veracruz, Mexico

A study and spatiotemporal radiological characterization of water for human use and consumption in the main rural populations of the center of the State of Veracruz was carried out, covering 22 municipalities. The objective was to estimate the annual effective dose as a function of the concentration of gross alpha and beta activity. For this purpose, a low background proportional flux detection system calibrated with NIST-traceable radioactive standards was used. Sampling included only wells, springs, and lagoons in rural areas that supply water to these populations. The decision was based on the fact that these do not have a physicochemical treatment and was carried out during the dry and rainy seasons, which became factors of impact on the radiological material. The analysis included the results of 195 samples from 22 municipalities which showed ranges in the gross alpha of 0.052-0.95 BqL-1 with a mean of 0.376 ±0.101BqL-1 and a gross beta of 0.034-1.48 BqL-1 with a mean of 0.389 ±0.108 BqL-1. The comparison of the values obtained with respect to those of other countries and their complement with analysis of variance showed that there was a significant difference, particularly, for the results of gross alpha in the municipality of Alto Lucero de Gutierrez Barrios and gross beta in Nautla and Tecolutla in dry and rainy seasons (at a probability of p≤0.05 with the Tukey-Kramer HSD statistical test). A correlation between gross alpha and gross beta was also performed with an r of -0.18 and -0.44 in dry and rainy seasons. This means that among the radionuclides, the major sources of beta radiation are uranium and thorium decay series radionuclides. For the determination of gross alpha, the municipalities in the mountainous zones showed lower values of this activity than the municipalities in the coastal zone. Gross alpha activity values of 0.95 ± 0.11 BqL-1 were detected in the municipality of Alto Lucero de Gutiérrez Barrios in the locality of Arroyo Agrio, which exceeded the limit of the Official Mexican Standard