Theoretical study of topological properties of ferromagnetic pyrite CoS₂

Since the discovery of the first topological material 15 years ago, the search for material realizations of novel topological phases has become the driving force of the field. While oftentimes we search for new materials, we forget that well established materials can also display very interesting topological properties. In this work, we revisit CoS2, a metallic ferromagnetic pyrite that has been extensively studied in the literature due to its magnetic properties. We study the topological features of its electronic band structure and identify Weyl nodes and nodal lines, as well as a symmetry-protected fourfold fermion close to the Fermi level. Looking at different surface cleavage planes, we observe both spin polarized Fermi arcs in the majority channel and drumhead states. These findings suggest that CoS2 is a promising platform to study topological phenomena, as well as a good candidate for spintronic applications

Experimental and theoretical assessment of native oxide in the superconducting TaN

In this manuscript, we show through an experimental-computational proof of concept the native oxide formation into superconducting TaN films. First, TaN was synthesized at an ultra-high vacuum system by reactive pulsed laser deposition and characterized in situ by X-ray photoelectron spectroscopy. The material was also characterized ex situ by X-ray diffraction, transmission electron microscopy, and the four-point probe method. It was detected that TaN contained considerable oxygen impurities (up to 26 %O) even though it was grown in an ultra-high vacuum chamber. Furthermore, the impurified TaN evidence a face-centered cubic crystalline structure only and exhibits superconductivity at 2.99 K. To understand the feasibility of the native oxide in TaN, we study the effect of incorporating different amounts of O atoms in TaN using ab-initio calculations. A thermodynamic stability analysis shows that a TaOxN1-x model increases its stability as oxygen is added, demonstrating that oxygen may always be present in TaN, even when obtained at ultra-high vacuum conditions. All analyzed models exhibit metallic behavior. Charge density difference maps reveal that N and O atoms have a higher charge density redistribution than Ta atoms. The electron localization function maps and line profiles indicate that Ta-O and Ta-N bonds are mainly ionic. As expected, stronger ionic behavior is observed in the Ta-O bonds due to the electronegativity difference between O and N atoms. Recent evidence points to superconductivity in bulk TaO, confirming the asseverations of superconductivity in our samples. The results discussed here highlight the importance of considering native oxide when reporting superconductivity in TaN films since the TaO regions formed in the compound may be key to understanding the different critical temperatures reported in the literature.Comment: 23 pages, 7 figure

Creencias sexistas y actitudes de violencia de género. Situación de estudiantes universitario del área de la salud. Cartagena - Colombia

Introduction: Violence towards women is a problem that attempts towards equalness, the development of social peace. Situation that is acknowledged as a factor associated with the deterioration in the quality of life of the individuals as it is constituted a violation of human rights. Target: To describe the degree of agreement and disagreement between the sexist beliefs and those that lead students in the health area of superior education institution of Cartagena. Materials and methods: Descriptive study, cross-sectional the calculated sample was of 509 students, selected through convenience sampling, the questionnaire of attitudes towards gender and violence was used. (C.A.G.V), the questionnaire was divided in two sections, the first one, deals with social demographics the second, sexist beliefs and violance.Results: The factor with the most disagreement and rejected to sexist beliefs it is factor 1 with 79% of participants in disagreement, the factors 2,3,4 a high percentage is shown of disagreement and indifference in men and women to the evaluated beliefs. Conclusion: It is concluded that exists behaviors that promote violence, and this study was evidenced domination, isolation and conducts that pass unnotified, this is how violence against women done by the partner or ex-partner opens fields to important health issues; problems that have shown an unbalanced and well-being psychosocial in long and short term.Introducción: La violencia contra la mujer es un problema que atenta contra la igualdad, el desarrollo y la paz social. Situación que se reconoce como factor asociado al deterioro en la calidad de vida de los individuos en la medida que se constituye en violación de los Derechos Humanos. Objetivo: Describir el grado de acuerdo o desacuerdo entre las creencias sexistas y las que conducen a la violencia en estudiantes del área de la salud de una Institución de Educación Superior de Cartagena. Materiales y métodos: Estudio descriptivo, transversal, la muestra calculada fue de 509 estudiantes, seleccionados mediante muestreo por conveniencia, se utilizó el cuestionario de Actitudes hacia el Género y la Violencia (C.A.G.V), el cuestionario se dividió en dos secciones, la primera, aborda datos sociodemográficos, la segunda, las creencias sexistas y violencia. Resultados: El factor con mayor desacuerdo y/o rechazo a las creencias sexistas es el factor 1 con un 79% de participantes en desacuerdo, los factores 2, 3 y 4 tiene presentan un alto porcentaje de desacuerdo y actitud indiferente en hombres y mujeres ante las creencias evaluadas. Conclusión: Se concluye que existen comportamientos que promueven la violencia, en este estudio se evidenció dominación, aislamiento y conductas que suelen pasar inadvertidas, es así como la violencia contra las mujeres ejercidas por sus parejas o ex parejas abre campos a importantes problemas de salud, problemas que han demostrado un desequilibrio del bienestar psicosocial a corto y/o a largo plazo

Disruption of both chloroplastic and cytosolic FBPase genes results in a dwarf phenotype and important starch and metabolite changes in Arabidopsis thaliana

In this study, evidence is provided for the role of fructose-1,6-bisphosphatases (FBPases) in plant development and carbohydrate synthesis and distribution by analysing two Arabidopsis thaliana T-DNA knockout mutant lines, cyfbp and cfbp1, and one double mutant cyfbp cfbp1 which affect each FBPase isoform, cytosolic and chloroplastic, respectively. cyFBP is involved in sucrose synthesis, whilst cFBP1 is a key enzyme in the Calvin–Benson cycle. In addition to the smaller rosette size and lower rate of photosynthesis, the lack of cFBP1 in the mutants cfbp1 and cyfbp cfbp1 leads to a lower content of soluble sugars, less starch accumulation, and a greater superoxide dismutase (SOD) activity. The mutants also had some developmental alterations, including stomatal opening defects and increased numbers of root vascular layers. Complementation also confirmed that the mutant phenotypes were caused by disruption of the cFBP1 gene. cyfbp mutant plants without cyFBP showed a higher starch content in the chloroplasts, but this did not greatly affect the phenotype. Notably, the sucrose content in cyfbp was close to that found in the wild type. The cyfbp cfbp1 double mutant displayed features of both parental lines but had the cfbp1 phenotype. All the mutants accumulated fructose-1,6-bisphosphate and triose-phosphate during the light period. These results prove that while the lack of cFBP1 induces important changes in a wide range of metabolites such as amino acids, sugars, and organic acids, the lack of cyFBP activity in Arabidopsis essentially provokes a carbon metabolism imbalance which does not compromise the viability of the double mutant cyfbp cfbp1.España, Ministerio de Economía y Competitividad BIO2009-07297España, Ministerio de Economía y Competitividad BIO2012-33292Junta de Andalucía P07-CVI-279

Disruption of both chloroplastic and cytosolic FBPase genes results in a dwarf phenotype and important starch and metabolite changes in Arabidopsis thaliana

In this study, evidence is provided for the role of fructose-1,6-bisphosphatases (FBPases) in plant development and carbohydrate synthesis and distribution by analysing two Arabidopsis thaliana T-DNA knockout mutant lines, cyfbp and cfbp1, and one double mutant cyfbp cfbp1 which affect each FBPase isoform, cytosolic and chloroplastic, respectively. cyFBP is involved in sucrose synthesis, whilst cFBP1 is a key enzyme in the Calvin–Benson cycle. In addition to the smaller rosette size and lower rate of photosynthesis, the lack of cFBP1 in the mutants cfbp1 and cyfbp cfbp1 leads to a lower content of soluble sugars, less starch accumulation, and a greater superoxide dismutase (SOD) activity. The mutants also had some developmental alterations, including stomatal opening defects and increased numbers of root vascular layers. Complementation also confirmed that the mutant phenotypes were caused by disruption of the cFBP1 gene. cyfbp mutant plants without cyFBP showed a higher starch content in the chloroplasts, but this did not greatly affect the phenotype. Notably, the sucrose content in cyfbp was close to that found in the wild type. The cyfbp cfbp1 double mutant displayed features of both parental lines but had the cfbp1 phenotype. All the mutants accumulated fructose-1,6-bisphosphate and triose-phosphate during the light period. These results prove that while the lack of cFBP1 induces important changes in a wide range of metabolites such as amino acids, sugars, and organic acids, the lack of cyFBP activity in Arabidopsis essentially provokes a carbon metabolism imbalance which does not compromise the viability of the double mutant cyfbp cfbp1.España, Ministerio de Economía y Competitividad BIO2009-07297España, Ministerio de Economía y Competitividad BIO2012-33292Junta de Andalucía P07-CVI-279