The c-completion of Lorentzian metric spaces

Inspired by some Lorentzian versions of the notion of metric and length space introduced by Kunzinger and Sämman [24], and more recently, by Müller [31], and Minguzzi and Sühr [30], we revisit the notion of Lorentzian metric space in order to later construct the c-completion of these general objects. We not only prove that this construction is feasible in great generality for these objects, including spacetimes of low regularity, but also endow the c-completion with a structure of Lorentzian metric space by itself. We also prove that the c-completion constitutes a well-suited extension of the original space, which really completes it in a precise sense and becomes sensible to certain causal properties of that space.Project PID2020-116126GB-I00 (funded by MCIN/AEI/10.13039/501100011033)IMAG-María de Maeztu grant CEX2020- 001105-M (funded by MCIN/AEI/10.13039/50110001103)Grants PID2020-118452GBI00 and PID2021-126217NBI00 (Spanish MICINN)PY20-01391 (PAIDI 2020, Junta de Andalucía-FEDER

Expression of p53 Protein and Tumor Angiogenesis as Prognostic Factors in Nasopharyngeal Carcinoma Patients.

The objective of this study was to evaluate the possible prognostic significance of p53 protein overexpression and tumor angiogenesis (TA) in nasopharyngeal carcinoma (NPC) patients, together with other clinicopathological variables. Forty-two NPC patients were evaluated in relation to survival. Nuclear p53 overexpression in neoplastic and endothelial cells was detected by immunohistochemistry (IHC) with the monoclonal antibody DO-7 and the polyclonal antibody against factor VIII-related antigen, respectively. Thereafter, we evaluated p53 cases in order to determine their nuclear immunoreactivity from negative (-) to positive (+, ++, +++). In addition, microvessels were counted in the most active areas of tumor neovascularization or hotspots using an image computer analyzer (MicroImage®). A Cox multiple regression survival analysis was used to determine the best prognostic indicators in NPC patients. As a result, tumor microvessel count, considered as a continuous variable, was the most important independent prognostic indicator in relation to survival (p = 0.0273), with a relative risk of death of 2,4399 [95% confidence interval = 1.1051 ; 5.3871] associated with the highest microvessel counts. Moreover, the only clinicopathological variable that demonstrated prognostic value in a Cox multiple regression survival analysis was histological type (p = 0.05). In addition, we did not observe any statistical association between intratumoral microvessel density (IMD), clinicopathological variables and p53 protein expression. Key words: p53 protein - Angiogenesis - Morphometry - Prognosis - Nasopharyngeal carcinom

Cobalt Metal-Organic Framework based on two dinuclear secondary building units for electrocatalytic oxygen evolution

The synthesis of a new microporous metal-organic framework (MOF) based on two secondary building units, with dinuclear cobalt centers, has been developed. The employment of a well-defined cobalt cluster results in an unusual topology of the Co2-MOF, where one of the cobalt centers has three open coordination positions, which has no precedent in MOF materials based on cobalt. Adsorption isotherms have revealed that Co2-MOF is in the range of best CO2 adsorbents among the carbon materials, with very high CO2/CH4 selectivity. On the other hand, dispersion of Co2-MOF in an alcoholic solution of Nafion gives rise to a composite (Co2-MOF@Nafion) with great resistance to hydrolysis in aqueous media and good adherence to graphite electrodes. In fact, it exhibits high electrocatalytic activity and robustness for the oxygen evolution reaction (OER), with a turnover frequency number value superior to those reported for similar electrocatalysts. Overall, this work has provided the basis for the rational design of new cobalt OER catalysts and related materials employing well-defined metal clusters as directing agents of the MOF structure

Coercivity and Magnetic Anisotropy of (Fe0.76Si0.09B0.10P0.05)97.5Nb2.0Cu0.5 Amorphous and Nanocrystalline Alloy Produced by Gas Atomization Process

We present the evolution of magnetic anisotropy obtained from the magnetization curve of (Fe0.76Si0.09B0.10P0.05)97.5Nb2.0Cu0.5 amorphous and nanocrystalline alloy produced by a gas atomization process. The material obtained by this process is a powder exhibiting amorphous character in the as-atomized state. Heat treatment at 480 °C provokes structural relaxation, while annealing the powder at 530 °C for 30 and 60 min develops a fine nanocrystalline structure. Magnetic anisotropy distribution is explained by considering dipolar effects and the modified random anisotropy model.Author Kenny L. Alvarez thanks Becas Chile (CONICYT) for financial support. The authors thank SGIker of UPV/EHU for technical and human support. This work was supported by the European Commission (ERDF and ESF programs). Authors M. Ipatov, L. Domínguez and J. Gonzalez acknowledge the University of the Basque Country for the support under the scheme “Ayudas a Grupos Consolidados” (Ref. PPG17/35)

Ecofisiología del cultivo de Mandioca consociado con Albahaca y Coriandro en el Subtropico de Argentina

La mandioca es un cultivo que admiten consociarse con diversas especies. El objetivo de este trabajo fue evaluar la factibilidad de su consociación con dos cultivos condimentarios, albahaca y coriandro, comparando los componentes del rendimiento de las tres especies bajo el sistema consociado versus sus respectivos monocultivos. El ensayo se realizó en Corrientes, Argentina. Los tratamientos consistieron en tres monocultivos (T2: mandioca, T3: albahaca, T4: coriandro) y un consociado (Tl), dispuestos en un diseño de bloques completos al azar con tres repeticiones. Los resultados se analizaron estadísticamente a través de la Prueba de t con muestras no pareada<> (0,05%). Los resultados mostraron que en el T1, los componentes del rendimiento del cultivo de mandioca sufrieron reducciones significativas en relación al T2, hubo un incremento significativo del rendimiento del coriandro mediado por el mayor peso de granos por planta en relación al T4, y finalmente el peso fresco y seco de plantas de albahaca, y su partición entre órganos resultó indiferente a los tratamientos. El índice de uso eficiente de la tierra (UET) calculado para este policultivo fue de 3, lo que demuestra la factibilidad del sistema, permitiendo diversificar la producción para una agricultura sostenible

Cobalt metal-organic framework based on layered double nanosheets for enhanced electrocatalytic water oxidation in neutral media

A new cobalt metal-organic framework (2D-Co-MOF) based on well-defined layered double cores that are strongly connected by intermolecular bonds has been developed. Its 3D structure is held together by π-π stacking interactions between the labile pyridine ligands of the nanosheets. In aqueous solution, the axial pyridine ligands are exchanged by water molecules, producing a delamination of the material, where the individual double nanosheets preserve their structure. The original 3D layered structure can be restored by a solvothermal process with pyridine, so that the material shows a "memory effect" during the delamination-pillarization process. Electrochemical activation of a 2D-Co-MOF@Nafion-modified graphite electrode in aqueous solution improves the ionic migration and electron transfer across the film and promotes the formation of the electrocatalytically active cobalt species for the oxygen evolution reaction (OER). The so-activated 2D-Co-MOF@Nafion composite exhibits an outstanding electrocatalytic performance for the OER at neutral pH, with a TOF value (0.034 s-1 at an overpotential of 400 mV) and robustness superior to those reported for similar electrocatalysts under similar conditions. The particular topology of the delaminated nanosheets, with quite distant cobalt centers, precludes the direct coupling between the electrocatalytically active centers of the same sheet. On the other hand, the increase in ionic migration across the film during the electrochemical activation stage rules out the intersheet coupling between active cobalt centers, as this scenario would impair electrolyte permeation. Altogether, the most plausible mechanism for the O-O bond formation is the water nucleophilic attack to single Co(IV)-oxo or Co(III)-oxyl centers. Its high electrochemical efficiency suggests that the presence of nitrogen-containing aromatic equatorial ligands facilitates the water nucleophilic attack, as in the case of the highly efficient cobalt porphyrins

Electronic transport in gadolinium atomic-size contacts

We report on the fabrication, transport measurements, and density functional theory (DFT) calculations of atomic-size contacts made of gadolinium (Gd). Gd is known to have local moments mainly associated with f electrons. These coexist with itinerant s and d bands that account for its metallic character. Here we explore whether and how the local moments influence electronic transport properties at the atomic scale. Using both scanning tunneling microscope and lithographic mechanically controllable break junction techniques under cryogenic conditions, we study the conductance of Gd when only few atoms form the junction between bulk electrodes made of the very same material. Thousands of measurements show that Gd has an average lowest conductance, attributed to single-atom contact, below 2e2h. Our DFT calculations for monostrand chains anticipate that the f bands are fully spin polarized and insulating and that the conduction may be dominated by s, p, and d bands. We also analyze the electronic transport for model nanocontacts using the nonequilibrium Green's function formalism in combination with DFT. We obtain an overall good agreement with the experimental results for zero bias and show that the contribution to the electronic transport from the f channels is negligible and that from the d channels is marginal.B.O., C.S., J.F.R., J.J.P., and C.U. acknowledge financial support by MEC-Spain (Grant No. FIS2013-47328-C2 and MAT2016-78625-C2) and the Generalitat Valenciana under Grant No. PROMETEO/2012/011. C.S. and J.J.P. acknowledge the EU structural funds and the Comunidad de Madrid under NANOFRONTMAG-CM program Grant No. S2013/MIT-2850. J.L.L. and J.F.R. acknowledge Marie Curie ITN SPINOGRAPH FP7 under REA Grant Agreement No. 607904-13. B.O. acknowledges financial support by MEC Spain (Grant No. FIS2010-21883-C02-01) under brief stays abroad scholarship

Bimetallic Intersection in PdFe@FeOx-C Nanomaterial for Enhanced Water Splitting Electrocatalysis

Supported Fe-doped Pd-nanoparticles (NPs) are prepared via soft transfor-mation of a PdFe-metal oraganic framework (MOF). The thus synthesized bimetallic PdFe-NPs are supported on FeOx@C layers, which are essential for developing well-defined and distributed small NPs, 2.3 nm with 35% metal loading. They are used as bifunctional nanocatalysts for the electro-catalytic water splitting process. They display superior mass activity for the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), both in alkaline and acid media, compared with those obtained for benchmarking platinum HER catalyst, and ruthenium, and iridium oxide OER catalysts. PdFe-NPs also exhibit outstanding stability against sintering that can be explained by the protecting role of graphitic carbon layers provided by the organic linker of the MOF. Additionally, the superior electrocatalytic performance of the bimetallic PdFe-NPs compared with those of monometallic Pd/C NPs and FeOx points to a synergetic effect induced by Fe-Pd interactions that facilitates the water splitting reaction. This is supported by additional characterization of the PdFe-NPs prior and post electrolysis by TEM, XRD, X-ray photoelectron spectroscopy, and Raman revealing that dispersed PdFe NPs on FeOx@C promote interactions between Pd and Fe, most likely to be Pd-O-Fe active centers

Internal friction associated with ε martensite in shape memory steels produced by casting route and through additive manufacturing: Influence of thermal cycling on the martensitic transformation

Among the different families of shape memory alloys (SMA), the Fe-Mn-Si-Cr-Ni alloys have attracted a renewed interest because of its low cost, high corrosion resistance and high recovery strength during the shape memory effect, and the new technologies of additive manufacturing offer unforeseen possibilities for this family of SMA. In the present work, the reversible gamma - epsilon martensitic transformation (MT), responsible for the shape memory effect, is studied in two Fe-Mn-Si-Cr-Ni alloys with high (20.2 wt%) and low (15.8 wt%) Mn content, produced by the conventional route of casting and rolling, in comparison with the MT in another similar alloy, with intermediate Mn content (19.4 wt%), which was produced by gas atomization and additive manufacturing through laser metal deposition. The forward and reverse gamma - epsilon MT is studied by mechanical spectroscopy through the internal friction spectra and the dynamic modulus variation, together with a parallel microstructural characterization including in-situ observation of the gamma - epsilon MT during cooling and heating at the scanning electron microscope. The evolution of the transformed fraction of epsilon martensite, evaluated through the integral area of the internal friction peak, was followed along thermal cycling in all three alloys. Both, the internal friction and the electron microscopy studies show that the epsilon martensite amount increases very fast during the first few cycles, and then decreases with a tendency towards its stabilization for many tens of cycles. The results show that the gamma - epsilon MT is more stable on cycling in the additive manufactured sample than in the conventionally processed samples, opening new avenues for designing shape memory steels to be specifically processed through additive manufacturing.This work was supported by the ELKARTEK-CEMAP (KK-2020/00047) project from the Industry Department of the Basque Government, and the GIU-17/071 from the University of the Basque Country, UPV/EHU. This work made use of the SGIKER facilities at the UPV/EHU

Utilización del túnel de viento como herramienta para el análisis de tanques de petróleo en la Norpatagonia

En este trabajo se presentan una serie de ensayos realizados en túnel de viento, sobre distintos modelos de tanques correspondientes a dimensiones que se emplean con frecuencia en la industria del petróleo en las provincias de Río Negro y Neuquén, unos para analizar los colapsos ocurridos en tanques aislados y en fase de construcción, otros sobre tanques agrupados en baterías para cuantificar las sobrecargas que se generan por interferencia entre los mismos. Los modelos ensayados correspondientes a tanques en etapa constructiva tienen la condición de abierto en la parte superior, ya que el techo aun no estaba montado, mientras que los modelos para evaluar el efecto de grupo tienen techo cónico, considerándose diferentes separaciones entre ambos y direcciones de incidencia de viento variables. Los ensayos arrojaron patrones de flujos que produjeron cargas adicionales que no se tienen en cuenta en las actuales normas de diseño. Los coeficientes de presión medidos permiten realizar modelaciones numéricas para analizar la estabilidad de los tanques.Laboratorio de Capa Límite y Fluidodinámica AmbientalGrupo Fluidodinámica Computaciona