A Green's function approach to Topological Insulator junctions with magnetic and superconducting regions

This work presents a Green's function approach, originally implemented in graphene with well-defined edges, to the surface of a strong 3D Topological Insulator (TI) with a sequence of proximitized superconducting (S) and ferromagnetic (F) surfaces. This consists of the derivation of the Green's functions for each region by the asymptotic solutions method, and their coupling by a tight-binding Hamiltonian with the Dyson equation to obtain the full Green's functions of the system. These functions allow the direct calculation of the momentum-resolved spectral density of states, the identification of subgap interface states, and the derivation of the differential conductance for a wide variety of configurations of the junctions. We illustrate the application of this method for some simple systems with two and three regions, finding the characteristic chiral state of the Quantum Anomalous Hall Effect (QAHE) at the NF interfaces, and chiral Majorana modes at the NS interfaces. Finally, we discuss some geometrical effects present in three-region junctions such as weak Fabry-P\'erot resonances and Andreev bound states.Comment: 14 pages, 6 figure

Índices de seguridad de voltaje calculados con datos de unidades fasoriales de medida

Las unidades de medida fasorial son un recurso tecnológico que permite observar con gran precisión el estado dinámico del sistema eléctrico de potencia. Su aplicación permite, entre muchas otras cosas, implementar índices para evaluar en tiempo real la seguridad de voltaje. Este artículo presenta una breve historia del desarrollo de estos índices y una propuesta inicial de escalas semánticas - gráficas para tres de ellos, con el fin de expresar en forma cualitativa al operador del centro de control el estado de la seguridad de voltaje del sistema

Crianza artificial de terneros y eficiencia en la utilización de la úrea

Muchos sistemas para la cría de terneros se han ensayado en diferentes países, empleando reemplazo total 0 parcial de La alimentación láctea por sustitutos que puedan supl1r los requerimientos para el desarrollo normal de los animales, la gran escasez de leche en la actualidad tanto para el consumo humano como para la industria procesadora, es una de las condiciones que conduce a buscar Sistemas de cría de terneros con reducidas cantidades de leche por cortos períodos de alimentación láctea, dando como resultado una mayor cantidad de leche disponible, que puede aumentar los niveles de venta en los mercados, ocasionando así la capacidad para un mayor consumo por persona y al mismo tiempo haciendo más rentables las explotaciones ganadera

Análisis de estabilidad de voltaje en reconfiguración de circuitos primarios de distribución

La estabilidad de voltaje determina la máxima cargabilidad de un sistema de potencia y la reconfiguración de circuitos primarios de distribución determina alternativas óptimas de conexión de la cargas para aumentar la confiabilidad del servicio Aunque fuertemente relacionados entre si estos análisis han sido tradicionalmente realizados en forma independiente así este artículo presenta un estudio sobre la relación existente entre ellos El principal resultado es que el criterio de minimización de pérdidas aplicado en el análisis de reconfiguración lleva implícitamente a la mejora de la estabilidad de voltaje pero un análisis explicito de estabilidad permite identificar soluciones alternas de reconfiguración que sin ser óptimas brindan buena cargabilidad y estabilidad

Medidas para mitigar problemas de estabilidad de voltaje

Actualmente existe una gran cantidad de información sobre estabilidad de voltaje en sistemas de potencia, la mayor parte de la cual trata sobre las metodologías para detectar las condiciones operativas que pueden llevar a problemas de inestabilidad y colapso. Sin embargo, un asunto de gran interés para quienes planean y operan los sistemas de potencia son las medidas que se pueden aplicar para mitigar estos problemas. Así, en este artículo se presenta un inventario de estas medidas, su descripción, taxonomía y áreas actuales de investigación y desarrollo

Evaluation of metabolic changes in acute intermittent porphyria patients by targeted metabolomics

Acute intermittent porphyria (AIP) is an inherited rare hepatic disorder due to mutations within the hydroxymethylbilane gene. AIP patients with active disease overproduce aminolevulinic acid (ALA) and porphobilinogen (PBG) in the liver which are exported inducing severe neurological attacks. Different hepatic metabolic abnormalities have been described to be associated with this condition. The goal of this research was to explore the metabolome of symptomatic AIP patients by state-of-the art liquid chromatography-tandem mass spectrometry (LC-MS/MS). A case versus control study including 18 symptomatic AIP patients and 33 healthy controls was performed. Plasmatic levels of 51 metabolites and 16 ratios belonging to four metabolic pathways were determined. The results showed that the AIP patients presented significant changes in the two main areas of the metabolome under study: (a) the tryptophan/kynurenine pathway with an increase of tryptophan in plasma together with increase of the kynurenine/tryptophan ratio; and (b) changes in the tricarboxylic acid cycle (TCA) including increase of succinic acid and decrease of the fumaric acid/succinic acid ratio. We performed a complementary in vitro study adding ALA to hepatocytes media that showed some of the effects on the TCA cycle were parallel to those observed in vivo. Our study confirms in plasma previous results obtained in urine showing that AIP patients present a moderate increase of the kynurenine/tryptophan ratio possibly associated with inflammation. In addition, it also reports changes in the mitochondrial TCA cycle that, despite requiring further research, could be associated with an energy misbalance due to sustained overproduction of heme-precursors in the liver.This research was funded by Instituto de Salud Carlos III FEDER (grant number PI14/00147), Generalitat de Catalunya (research team grant number 2014SGR692) and Spanish Health National System (contract number CPII16/00027 for Oscar J Pozo).Peer ReviewedPostprint (published version

Group 10 Metal Benzene-1,2-dithiolate Derivatives in the Synthesis of Coordination Polymers Containing Potassium Countercations

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Inorganic Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/abs/10.1021/acs.inorgchem.7b01775The use of theoretical calculations has allowed us to predict the coordination behavior of dithiolene [M(SC6H4S)2]2- (M = Ni, Pd, Pt) entities, giving rise to the first organometallic polymers {[K2(μ-H2O)2][Ni(SC6H4S)2]}n and {[K2(μ-H2O)2(thf)]2[K2(μ-H2O)2(thf)2][Pd3(SC6H4S)6]}n by one-pot reactions of the corresponding d10 metal salts, 1,2-benzenedithiolene, and KOH. The polymers are based on σ,π interactions between potassium atoms and [M(SC6H4S)2]2- (M = Ni, Pd) entities. In contrast, only σ interactions are observed when the analogous platinum derivative is used instead, yielding the coordination polymer {[K2(μ-thf)2][Pt(SC6H4S)2]}nThis work was supported in part by the MICINN (grants MAT2016-77608-C3-1-P and MAT2016-75883-C2-1-P), Generalitat Valenciana (PrometeoII/2014/076), and ISIC. J.I.M. acknowledges financial support by the “Ramon y Cajal ́ ” Program of MINECO (RYC-2015-17730

Conservation and global distribution of non-canonical antigens in enterotoxigenic Escherichia coli

BACKGROUND: Enterotoxigenic Escherichia coli (ETEC) cause significant diarrheal morbidity and mortality in children of resource-limited regions, warranting development of effective vaccine strategies. Genetic diversity of the ETEC pathovar has impeded development of broadly protective vaccines centered on the classical canonical antigens, the colonization factors and heat-labile toxin. Two non-canonical ETEC antigens, the EtpA adhesin, and the EatA mucinase are immunogenic in humans and protective in animal models. To foster rational vaccine design that complements existing strategies, we examined the distribution and molecular conservation of these antigens in a diverse population of ETEC isolates. METHODS: Geographically diverse ETEC isolates (n = 1159) were interrogated by PCR, immunoblotting, and/or whole genome sequencing (n = 46) to examine antigen conservation. The most divergent proteins were purified and their core functions assessed in vitro. RESULTS: EatA and EtpA or their coding sequences were present in 57.0% and 51.5% of the ETEC isolates overall, respectively; and were globally dispersed without significant regional differences in antigen distribution. These antigens also exhibited \u3e93% amino acid sequence identity with even the most divergent proteins retaining the core adhesin and mucinase activity assigned to the prototype molecules. CONCLUSIONS: EtpA and EatA are well-conserved molecules in the ETEC pathovar, suggesting that they serve important roles in virulence and that they could be exploited for rational vaccine design

Innovative Microstructural Transformation upon CO2 Supercritical Conditions on Metal-Nucleobase Aerogel and Its Use as Effective Filler for HPLC Biomolecules Separation

This work contributes to enlightening the opportunities of the anisotropic scheme of non-covalent interactions present in supramolecular materials. It provides a top-down approach based on their selective disruption that herein has been employed to process a conventional microcrystalline material to a nanofibrillar porous material. The developed bulk microcrystalline material contains uracil-1-propionic acid (UPrOH) nucleobase as a molecular recognition capable building block. Its crystal structure consists of discrete [Cu(UPrO)2 (4,4′-bipy)2 (H2 O)] (4,4′-bipy=4,4′-bipyridine) entities held together through a highly anisotropic scheme of non-covalent interactions in which strong hydrogen bonds involving coordinated water molecules provide 1D supramolecular chains interacting between them by weaker interactions. The sonication of this microcrystalline material and heating at 45 °C in acetic acid–methanol allows partial reversible solubilization/recrystallization processes that promote the cross-linking of particles into an interlocked platelet-like micro-particles metal–organic gel, but during CO2 supercritical drying, the microcrystalline particles undergo a complete morphological change towards highly anisotropic nanofibers. This unprecedented top-down microstructural conversion provides a nanofibrillar material bearing the same crystal structure but with a highly increased surface area. Its usefulness has been tested for HPLC separation purposes observing the expected nucleobase complementarity-based separation.We thank the grant CTQ2017-87201-P funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe” for financial support; and Generalidat Valenciana (Prometeo/2019/076). We thank the grant PID2019-108028GB-C22 and PID2019-108028GB-C21 funded by MCIN/AEI 10.13039/501100011033.We thank the grant FEDERPID2020-118422-GB-I00 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe” for financial support; and the Basque Government (Grupos IT908-16)