Magnetic and elastic anisotropy in magnetorheological elastomers using nickel-based nanoparticles and nanochains

Nickel (Ni) based nanoparticles and nanochains were incorporated as fillers in polydimethylsiloxane (PDMS) elastomers and then these mixtures were thermally cured in the presence of a uniform magnetic field. In this way, macroscopically structured-anisotropic PDMS-Ni based magnetorheological composites were obtained with the formation of pseudo-chains-like structures (referred as needles) oriented in the direction of the applied magnetic field when curing. Nanoparticles were synthesized at room temperature, under air ambient atmosphere (open air, atmospheric pressure) and then calcined at 400 °C (in air atmosphere also). The size distribution was obtained by fitting SAXS experiments with a polydisperse hard spheres model and a Schulz-Zimm distribution, obtaining a size distribution centered at (10.0 - 0.6) nm with polydispersivity given by sigma= (8.0 ± 0.2) nm. The SAXS, XRD and TEM experiments are consistent with single crystal nanoparticles of spherical shape (average particle diameter obtained by TEM: (12 ± 1) nm). Nickel-based nanochains (average diameter: 360 nm; average length: 3 mm, obtained by SEM; aspect ratio=length/diameter ~10) were obtained at 85 ºC and ambient atmosphere (open air, atmospheric pressure). The magnetic properties of Ni-based nanoparticles and nanochains at room temperature are compared and discussed in terms of surface and size effects. Both Ni-based nanoparticles and nanochains were used as fillers for obtaining the PDMS structured magnetorheological composites, observing the presence of oriented needles. Magnetization curves, ferromagnetic resonance spectra (FMR) and strain-stress curves of low filler´s loading composites (2% w/w of fillers) were determined as functions of the relative orientation respect to the needles. The results indicate that even at low loadings it is possible to obtain magnetorheological composites with anisotropic properties, with larger anisotropy when using nanochains. For instance, the magnetic remanence, the FMR-resonance field and the elastic response to compression are higher when measured parallel to the needles (about 30% with nanochains as fillers). Analogously, the elastic response is also anisotropic, with larger anisotropy when using nanochains as fillers. Therefore, all experiments performed confirm the high potential of nickel nanochains to induce anisotropic effects in magnetorheological materials.Fil: Landa, Romina Ailín. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Química Física de los Materiales del Medioambiente y Energía; Argentina;Fil: P Soledad Antonel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Química Física de los Materiales del Medioambiente y Energía; Argentina;Fil: Mariano M. Ruiz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Química Física de los Materiales del Medioambiente y Energía; Argentina;Fil: Oscar E Pérez. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Industrias;Fil: Alejandro Butera. Comisión Nacional de Energía Atómica;Fil: Guillermo Jorge. Universidad Nacional de General Sarmiento;Fil: Cristiano L. P. Oliveira. Instituto de Física, Universidade De São Paulo; Brasil;Fil: Martín Negri. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Industrias

Pediatric Hospitalizations Associated with 2009 Pandemic Influenza A (H1N1) in Argentina

Fil: Libster, Romina. Fundación Infant, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Bugna, Jimena. Fundación Infant, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Coviello, Silvina. Fundación Infant, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Hijano, Diego R. Hospital De Niños Sor María Ludovica, La Plata; Argentina.Fil: Dunaiewsky, Mariana. Hospital General de Niños Pedro de Elizalde, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Reynoso, Natalia. Hospital Municipal Materno Infantil de San Isidro; Argentina.Fil: Cavalieri, Maria L. Hospital Eva Perón, Benito Juárez, Buenos Aires; ArgentinaFil: Guglielmo, Maria C. Hospital General de Niños Pedro de Elizalde, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Areso, M. Soledad. Hospital Eva Perón, Benito Juárez, Buenos Aires; ArgentinaFil: Gilligan, Tomas. Hospital General de Agudos Carlos G. Durand, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Santucho, Fernanda. Hospital General de Agudos Carlos G. Durand, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Cabral, Graciela. Hospital Nacional Profesor Alejandro Posadas, El Palomar, Buenos Aires; Argentina.Fil: Gregorio, Gabriela L. Hospital Nacional Profesor Alejandro Posadas, El Palomar, Buenos Aires; Argentina.Fil: Moreno, Rina. Hospital Nacional Profesor Alejandro Posadas, El Palomar, Buenos Aires; Argentina.Fil: Lutz, Maria I. Hospital Nacional Profesor Alejandro Posadas, El Palomar, Buenos Aires; Argentina.Fil: Panigasi, Alicia L. Hospital Nacional Profesor Alejandro Posadas, El Palomar, Buenos Aires; Argentina.Fil: Saligari, Liliana. Hospital Nacional Profesor Alejandro Posadas, El Palomar, Buenos Aires; Argentina.Fil: Caballero, Mauricio T. Hospital De Niños Sor María Ludovica, La Plata; Argentina.Fil: Egües Almeida, Rodrigo M. Hospital De Niños Sor María Ludovica, La Plata; Argentina.Fil: Gutierrez Meyer, Maria E. Hospital De Niños Sor María Ludovica, La Plata; Argentina.Fil: Neder, Maria D. Hospital General de Niños Pedro de Elizalde, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Davenport, Maria C. Hospital General de Niños Pedro de Elizalde, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Del Valle, Maria P. Hospital General de Niños Pedro de Elizalde, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Santidrian, Valeria S. Hospital General de Niños Pedro de Elizalde, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Mosca, Guillermina. Ministerio de Ciencia, Técnica e Innovación. Fundación Infant, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Alvarez, Liliana. Hospital General de Agudos Carlos G. Durand, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Landa, Patricia. Hospital General de Agudos Carlos G. Durand, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Pota, Ana. Hospital General de Agudos Carlos G. Durand, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Boloñati, Norma. Hospital General de Agudos Carlos G. Durand, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Dalamon, Ricardo. Hospital General de Agudos Carlos G. Durand, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Sanchez Mercol, Victoria I. Hospital Eva Perón, Benito Juárez, Buenos Aires; Argentina.Fil: Espinoza, Marco. Fundación Infant, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Peuchot, Juan Carlos. Hospital Eva Perón, Benito Juárez, Buenos Aires; Argentina.Fil: Karolinski, Ariel. Hospital General de Agudos Carlos G. Durand, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Bruno, Miriam. Hospital General de Agudos Carlos G. Durand, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Borsa, Ana. Hospital General de Niños Pedro de Elizalde, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Ferrero, Fernando. Hospital General de Niños Pedro de Elizalde, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Bonina, Angel. Hospital De Niños Sor María Ludovica, La Plata; Argentina.Fil: Ramonet, Margarita. Hospital Nacional Profesor Alejandro Posadas, El Palomar, Buenos Aires; Argentina.Fil: Albano, Lidia C. Hospital Nacional Profesor Alejandro Posadas, El Palomar, Buenos Aires; Argentina.Fil: Luedicke, Nora. Ministerio de Ciencia, Técnica e Innovación. Fundación Infant, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Alterman, Elias. Fundación Infant, Ciudad Autónoma de Buenos Aires; Argentina.Fil: Savy, Vilma L. ANLIS Dr.C.G.Malbrán. Instituto de Enfermedades Infecciosas; Argentina.Fil: Baumeister, Elsa. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Virología. Servicio de Virosis Respiratoria; Argentina.Fil: Chappell, James D. Vanderbilt University. Pathology, Nashville, Tennessee; Estados Unidos.Fil: Edwards, Kathryn M. Vanderbilt University. Departments of Pediatrics, Nashville, Tennessee; Estados Unidos.Fil: Melendi, Guillermina A. Vanderbilt University. Departments of Pediatrics, Nashville, Tennessee; Estados Unidos.Fil: Polack, Fernando P. Vanderbilt University. Departments of Pediatrics, Nashville, Tennessee; Estados Unidos.Background: While the Northern Hemisphere experiences the effects of the 2009 pandemic influenza A (H1N1) virus, data from the recent influenza season in the Southern Hemisphere can provide important information on the burden of disease in children. Methods: We conducted a retrospective case series involving children with acute infection of the lower respiratory tract or fever in whom 2009 H1N1 influenza was diagnosed on reverse-transcriptase polymerase-chain-reaction assay and who were admitted to one of six pediatric hospitals serving a catchment area of 1.2 million children. We compared rates of admission and death with those among age-matched children who had been infected with seasonal influenza strains in previous years. Results: Between May and July 2009, a total of 251 children were hospitalized with 2009 H1N1 influenza. Rates of hospitalization were double those for seasonal influenza in 2008. Of the children who were hospitalized, 47 (19%) were admitted to an intensive care unit, 42 (17%) required mechanical ventilation, and 13 (5%) died. The overall rate of death was 1.1 per 100,000 children, as compared with 0.1 per 100,000 children for seasonal influenza in 2007. (No pediatric deaths associated with seasonal influenza were reported in 2008.) Most deaths were caused by refractory hypoxemia in infants under 1 year of age (death rate, 7.6 per 100,000). Conclusions: Pandemic 2009 H1N1 influenza was associated with pediatric death rates that were 10 times the rates for seasonal influenza in previous years

A large sub-Neptune transiting the thick-disk M4 v TOI-2406

Context. Large sub-Neptunes are uncommon around the coolest stars in the Galaxy and are rarer still around those that are metal-poor. However, owing to the large planet-to-star radius ratio, these planets are highly suitable for atmospheric study via transmission spectroscopy in the infrared, such as with JWST. Aims. Here we report the discovery and validation of a sub-Neptune orbiting the thick-disk, mid-M dwarf star TOI-2406. The star's low metallicity and the relatively large size and short period of the planet make TOI-2406 b an unusual outcome of planet formation, and its characterisation provides an important observational constraint for formation models. Methods. We first infer properties of the host star by analysing the star's near-infrared spectrum, spectral energy distribution, and Gaia parallax. We use multi-band photometry to confirm that the transit event is on-target and achromatic, and we statistically validate the TESS signal as a transiting exoplanet. We then determine physical properties of the planet through global transit modelling of the TESS and ground-based time-series data. Results. We determine the host to be a metal-poor M4 V star, located at a distance of 56 pc, with properties Teff = 3100 ± 75 K, M∗ = 0.162 ± 0.008Mo˙, R∗ = 0.202 ± 0.011Ro˙, and [Fe∕ H] = -0.38 ± 0.07, and a member of the thick disk. The planet is a relatively large sub-Neptune for the M-dwarf planet population, with Rp = 2.94 ± 0.17R⊕ and P= 3.077 d, producing transits of 2% depth. We note the orbit has a non-zero eccentricity to 3σ, prompting questions about the dynamical history of the system. Conclusions. This system is an interesting outcome of planet formation and presents a benchmark for large-planet formation around metal-poor, low-mass stars. The system warrants further study, in particular radial velocity follow-up to determine the planet mass and constrain possible bound companions. Furthermore, TOI-2406 b is a good target for future atmospheric study through transmission spectroscopy. Although the planet's mass remains to be constrained, we estimate the S/N using amass-radius relationship, ranking the system fifth in the population of large sub-Neptunes, with TOI-2406 b having a much lower equilibrium temperature than other spectroscopically accessible members of this population.Fil: Wells, R. D.. University of Bern; SuizaFil: Rackham, B. V.. Massachusetts Institute of Technology; Estados UnidosFil: Schanche, N.. University of Bern; SuizaFil: Petrucci, Romina Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Gómez Maqueo Chew, Y.. Universidad Nacional Autónoma de México; MéxicoFil: Demory, Brice Olivier. University of Bern; SuizaFil: Burgasser, A. J.. University of California at San Diego; Estados UnidosFil: Burn, R.. Max Planck Institute for Astronomy; AlemaniaFil: Pozuelos, F. J.. Université de Liège; BélgicaFil: Günther, M. N.. Massachusetts Institute of Technology; Estados UnidosFil: Sabin, L.. Universidad Nacional Autónoma de México; MéxicoFil: Schroffenegger, U.. University of Bern; SuizaFil: Gómez Muñoz, M. A.. Universidad Nacional Autónoma de México; MéxicoFil: Stassun, K. G.. Vanderbilt University; Estados UnidosFil: Van Grootel, V.. Université de Liège; BélgicaFil: Howell, S. B.. National Aeronautics and Space Administration; Estados UnidosFil: Sebastian, D.. University of Birmingham; Reino UnidoFil: Triaud, A. H. M. J.. University of Birmingham; Reino UnidoFil: Apai, D.. University of Arizona; Estados UnidosFil: Plauchu Frayn, I.. Universidad Nacional Autónoma de México; MéxicoFil: Guerrero, C. A.. Universidad Nacional Autónoma de México; MéxicoFil: Guillén, P. F.. Universidad Nacional Autónoma de México; MéxicoFil: Landa, A.. Universidad Nacional Autónoma de México; MéxicoFil: Melgoza, G.. Universidad Nacional Autónoma de México; MéxicoFil: Montalvo, F.. Universidad Nacional Autónoma de México; MéxicoFil: Serrano, H.. Universidad Nacional Autónoma de México; MéxicoFil: Riesgo, H.. Universidad Nacional Autónoma de México; MéxicoFil: Barkaoui, K.. Université de Liège; Bélgica. Cadi Ayyad University; MarruecosFil: Bixel, A.. University of Arizona; Estados UnidosFil: Burdanov, A.. Massachusetts Institute of Technology; Estados Unido