Conductividad de mezclas de electrolitos simétricos y asimétricos en solución acuosa

El presente trabajo es un estudio sistemático de la conductividad eléctricade electrolitos simétricos, asimétricos y sus mezclas en soluciónacuosa. El estudio se centró en soluciones diluidas donde existen tratamientosteóricos con los que se pueden interpretar los valores de conductividadeléctrica hallados. Se estudiaron los sistemas BaCl2-NaCl [1] y MgCl2-NaCl [2,3] a 25°C. El estudio de las soluciones de MgCl2-NaCl se extendió hasta casi 4 M [4] de modo de conocer el comportamiento de este importante sistemaen todo el intervalo de concentración accesible a 25°C. Los datos de conductividad eléctrica determinados experimentalmentese analizaron mediante las ecuaciones de Lee y Wheaton y de Quinty Viallard. La descripción de los datos de conductividad se realizósobre la base de tres parámetros: A∞, Ka y d. La información experimentalde las mezclas estudiadas permitió conocer la dependencia delparámetro de máximo acercamiento entre iones con la composición delsistema. Debido al interés que presentan las medidas de conductividad a altatemperatura y presión se desarrolló un equipo de medición capaz detrabajar hasta 200°C. El equipo se empleó en el estudio de solucionesacuosas diluidas de Ba(OH)2, NaOH y una mezclas de ellos entre 75 y 150°C.Fil: Bianchi, Hugo Luis. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Cation immobilization in pyrolyzed simulated spent ion exchange resins

Significant quantities of spent ion exchange resins that are contaminated by an assortment of radioactive elements are produced by the nuclear industry each year. The baseline technology for the conditioning of these spent resins is encapsulation in ordinary Portland cement which has various shortcomings none the least of which is the relatively low loading of resin in the cement and the poor immobilization of highly mobile elements such as cesium. The present study was conducted with cationic resin samples (Lewatit S100) loaded with Cs +, Sr 2+, Co 2+, Ni 2+ in roughly equimolar proportions at levels at or below 30% of the total cation exchange capacity. Low temperature thermal treatment of the resins was conducted in inert (Ar), or reducing (CH 4) gas atmospheres, or supercritical ethanol to convert the hydrated polymeric resin beads into carbonaceous materials that contained no water. This pyrolytic treatment resulted in at least a 50% volume reduction to give mechanically robust spherical materials. Scanning electron microscope investigations of cross-sections of the beads combined with energy dispersive analysis showed that initially all elements were uniformly distributed through the resin matrix but that at higher temperatures the distribution of Cs became inhomogeneous. Although Cs was found in the entire cross-section, a significant proportion of the Cs occurred within internal rings while a proportion migrated toward the outer surfaces to form a crustal deposit. Leaching experiments conducted in water at 25°C showed that the divalent contaminant elements were very difficult to leach from the beads heated in inert atmospheres in the range 200-600°C. Cumulative fractional loses of the order of 0.001 were observed for these divalent elements for temperatures below 500°C. Regardless of the processing temperature, the cumulative fractional loss of Cs in water at 25°C reached a plateau or steady-state within the first 24 h increasing only marginally up 120 h. For unheated beads, a steady-state was reached at a cumulative fractional Cs loss of about 0.0045 while for beads heated to 400°C the steady-state was reached at a value of 0.1. Under comparable conditions leaching of Sr, Co and Ni were close to the detection limits. It is concluded that the fraction of the Cs inventory that was more readily leached derived mainly from Cs phases in the crustal deposit.Fil: Luca, Vittorio. Comisión Nacional de Energía Atómica; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Bianchi, Hugo Luis. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín; ArgentinaFil: Manzini, Alberto C.. Comisión Nacional de Energía Atómica; Argentin

Aerosol-assisted production of mesoporous titania microspheres with enhanced photocatalytic activity: The basis of an improved process

An aerosol-based process was used to prepare mesoporous TiO2 microspheres (MTM) with an average diameter in the range of 0.5-1 μm. The structural characteristics and photocatalytic properties of the synthesized materials were determined. As-prepared MTM materials and those heated in air from 400 to 600 °C exhibited mesoporous texture with a narrow size distribution and an inorganic framework that consisted of 4-13 nm anatase crystallites. Pore volumes for the MTM materials were in the range of 0.17-0.34 cm3 g-1. Microspheres heated to 400 °C presented a locally ordered mesopore structure and possessed X-ray diffraction d spacings between 9.8 and 17.3 nm. Heating above 400 °C resulted in a loss of the mesoscopic order, a decrease of the surface area, retention of the porosity, and an increase of the anatase nanoparticle size to 13 nm. The accessibility of the pore volume was measured by monitoring the uptake of gallic acid (GA) using Fourier transform IR. The MTM materials made excellent catalysts for the photodegradation of GA, with the performance being higher than that of an equivalent sample of Degussa P25. The present MTM materials are advantageous in terms of their ease of separation from the aqueous phase, and hence a novel photocatalytic process is proposed based on separate adsorption and photocatalytic decomposition steps with an improved and more rational use of both catalyst and sunlight.Fil: Araujo, Paula Zulema. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Luca, Vittorio. Australian Nuclear Science And Technology Organisation; Australia. Comisión Nacional de Energía Atómica; ArgentinaFil: Bozzano, Patricia B.. Comisión Nacional de Energía Atómica; ArgentinaFil: Bianchi, Hugo Luis. Universidad Nacional de San Martín; Argentina. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Soler Illia, Galo Juan de Avila Arturo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Blesa, Miguel Angel. Universidad Nacional de San Martín; Argentina. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

A genome-wide association study for survival from a multi-centre European study identified variants associated with COVID-19 risk of death

: The clinical manifestations of SARS-CoV-2 infection vary widely among patients, from asymptomatic to life-threatening. Host genetics is one of the factors that contributes to this variability as previously reported by the COVID-19 Host Genetics Initiative (HGI), which identified sixteen loci associated with COVID-19 severity. Herein, we investigated the genetic determinants of COVID-19 mortality, by performing a case-only genome-wide survival analysis, 60 days after infection, of 3904 COVID-19 patients from the GEN-COVID and other European series (EGAS00001005304 study of the COVID-19 HGI). Using imputed genotype data, we carried out a survival analysis using the Cox model adjusted for age, age2, sex, series, time of infection, and the first ten principal components. We observed a genome-wide significant (P-value < 5.0 × 10-8) association of the rs117011822 variant, on chromosome 11, of rs7208524 on chromosome 17, approaching the genome-wide threshold (P-value = 5.19 × 10-8). A total of 113 variants were associated with survival at P-value < 1.0 × 10-5 and most of them regulated the expression of genes involved in immune response (e.g., CD300 and KLR genes), or in lung repair and function (e.g., FGF19 and CDH13). Overall, our results suggest that germline variants may modulate COVID-19 risk of death, possibly through the regulation of gene expression in immune response and lung function pathways

Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe

Azimuthal anisotropy of charged jet production in root s(NN)=2.76 TeV Pb-Pb collisions

We present measurements of the azimuthal dependence of charged jet production in central and semi-central root s(NN) = 2.76 TeV Pb-Pb collisions with respect to the second harmonic event plane, quantified as nu(ch)(2) (jet). Jet finding is performed employing the anti-k(T) algorithm with a resolution parameter R = 0.2 using charged tracks from the ALICE tracking system. The contribution of the azimuthal anisotropy of the underlying event is taken into account event-by-event. The remaining (statistical) region-to-region fluctuations are removed on an ensemble basis by unfolding the jet spectra for different event plane orientations independently. Significant non-zero nu(ch)(2) (jet) is observed in semi-central collisions (30-50% centrality) for 20 <p(T)(ch) (jet) <90 GeV/c. The azimuthal dependence of the charged jet production is similar to the dependence observed for jets comprising both charged and neutral fragments, and compatible with measurements of the nu(2) of single charged particles at high p(T). Good agreement between the data and predictions from JEWEL, an event generator simulating parton shower evolution in the presence of a dense QCD medium, is found in semi-central collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe

Forward-central two-particle correlations in p-Pb collisions at root s(NN)=5.02 TeV

Two-particle angular correlations between trigger particles in the forward pseudorapidity range (2.5 2GeV/c. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B. V.Peer reviewe

Event-shape engineering for inclusive spectra and elliptic flow in Pb-Pb collisions at root(NN)-N-S=2.76 TeV

Peer reviewe

Mudanças religiosas e dinâmicas demográficas: mais além da teoria da secularização. O caso do catolicismo na cidade de Córdoba, Argentina

Este artículo explora críticamente las explicaciones de las dinámicas religiosas en Argentina basadas en la Teoría de la Secularización (TdS). La mayoría de sus referentes usa como variable independiente las relaciones político-institucionales; por eso, la TdS explica lo que sucede con la dirigencia de la institución y las organizaciones intermedias. Esta investigación recoge datos directos de los registros de bautismos durante un siglo en la ciudad de Córdoba (Argentina) y los compara con la tasa de natalidad. Este análisis muestra que eluso de variables político-institucionales no explica adecuadamente lo que sucede con las dinámicas religiosas, medidas en bautismos. La hipótesis propuesta es que las transformaciones religiosas se entienden mejor cuando se aplican variables demográficas.his article critically explores the explanations of religious dynamics in Argentina based on Secularization Theory (TdS). Most scholarship uses political-institutional relations as an independent variable; therefore, TdS focuses on what takes place within the leadership of the institution and intermediate organizations. This research collects data directly from a century of baptism records in the city of Córdoba (Argentina) and compares it with the city’s birth rate. This analysis shows that the use of political-institutional variables fails to adequately explain religious dynamics, as measured in baptisms. The proposed hypothesis is that religious transformations are better understood when demographic variables are applied.Este artigo explora criticamente as explicações das dinâmicas religiosas na Argentina baseadas na Teoria da Secularização (TdS). A maioria de seus referentes usa as relações político-institucionais como variável independente; por isso, a TdS explica o que acontece com a direção da instituição e das organizações intermediárias. Esta pesquisa recolhe dados diretos dos registros de batismos durante um século na cidade de Córdoba (Argentina) e os compara com a taxa de natalidade. Essa análise mostra que o uso de variáveis político-institucionais não explica adequadamente o que acontece com as dinâmicas religiosas, medidas em batismos. A hipótese proposta é que as transformações religiosas são melhor entendidas quando variáveis demográficas são aplicadas.Fil: Morello SJ, Gustavo. Boston College; Estados UnidosFil: Rabbia, Hugo Hernán. Universidad Nacional de Córdoba. Instituto de Investigaciones Psicológicas. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Psicológicas; Argentina. Universidad Católica de Córdoba. Facultad de Ciencias Politicas y Relaciones Internacionales; Argentin