Universal Scaling Law for the Size Effect on Superelasticity at the Nanoscale Promotes the Use of Shape‐Memory Alloys in Stretchable Devices

Shape-memory alloys (SMAs) are the most stretchable metallic materials thanks to their superelastic behavior associated with the stress-induced martensitic transformation. This property makes SMAs of potential interest for flexible and wearable electronic technologies, provided that their properties will be retained at small scale. Nanocompression experiments on Cu-Al-Be SMA single crystals demonstrate that micro- and nanopillars, between 2 mu m and 260 nm in diameter, exhibit a reproducible superelastic behavior fully recoverable up to 8% strain, even at the nanoscale. Additionally, these micro-/nanopillars exhibit a size effect on the critical stress for superelasticity, which dramatically increases for pillars smaller than approximate to 1 mu m in diameter, scaling with a power law of exponent n = -2. The observed size effect agrees with a theoretical model of homogeneous nucleation of martensite at small scale and the universality of this scaling power law for Cu-based SMAs is proposed. These results open new directions for using SMAs as stretchable conductors and actuating devices in flexible and wearable technologies.This work was supported by the Spanish Ministry of Economy and Competitiveness, MINECO, projects MAT2017-84069P and CONSOLIDER-INGENIO 2010 CSD2009-00013, as well as by the ELKARTEK-ACTIMAT project from the Industry Department of the Basque Government, and GIU-17/071 from the University of the Basque Country, UPV/EHU. This work made use of the FIB facilities of the SGIKER from the UPV/EHU. V.F. also acknowledges the Post-Doctoral Mobility Grant from the CONICET of Argentina, and J.F.G.-C. acknowledges the Post-Doctoral Grant (ESPDOC18/37) from the UPV/EHU

Person-to-Person Transmission of Andes Virus

Epidemiologic and genetic data show that person-to-person spread likely took place during the prodromal phase or shortly after it ended

Superelastic damping at nanoscale in ternary and quaternary Cu-based shape memory alloys

Superelasticity is a characteristic thermomechanical property in shape memory alloys (SMA), which is due to a reversible stress-induced martensitic transformation. Nano-compression experiments made possible the study of this property in Cu–Al–Ni SMA micropillars, showing an outstanding ultra-high mechanical damping capacity reproducible for thousands of cycles and reliable over the years. This scenario motivated the present work, where a comparative study of the damping capacity on four copper-based SMA: Cu–Al–Ni, Cu–Al–Be, Cu–Al–Ni–Be and Cu–Al–Ni–Ga is approached. For this purpose, [001] oriented single-crystal micropillars of comparable dimensions (around 1 µm in diameter) were milled by focused ion beam technique. All micropillars were cycled up to two hundred superelastic cycles, exhibiting a remarkable reproducibility. The damping capacity was evaluated through the dimensionless loss factor η, calculated for each superelastic cycle, representing the dissipated energy per cycle and unit of volume. The calculated loss factor was averaged between three micro-pillars of each alloy, obtaining the following results: Cu–Al–Ni η = 0.20 ± 0.01; Cu–Al–Be η = 0.100 ± 0.006; Cu–Al–Ni–Be η = 0.072 ± 0.004 and Cu–Al–Ni–Ga η = 0.042 ± 0.002. These four alloys exhibit an intrinsic superelastic damping capacity and offer a wide loss factor band, which constitutes a reference for engineering, since this kind of micro/nano structures can potentially be integrated not only as sensors and actuators but also as dampers in the design of MEMS to improve their reliability. In addition, the study of the dependence of the superelastic loss factor on the diameter of the pillar was approached in the Cu–Al–Ni–Ga alloy, and here we demonstrate that there is a size effect on damping at the nanoscale.Fil: Gómez Cortés, J.F.. Universidad del País Vasco; EspañaFil: Fuster, Valeria de Los Angeles. Universidad del País Vasco; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Pérez Cerrato, M.. Universidad del País Vasco; EspañaFil: Lorenzo, P.. Universidad del País Vasco; EspañaFil: Ruiz Larrea, I.. Universidad del País Vasco; EspañaFil: Breczewski, T.. Universidad del País Vasco; EspañaFil: Nó, M. L.. Universidad del País Vasco; EspañaFil: San Juan, J. M.. Universidad del País Vasco; Españ

Superelastic damping at nanoscale in ternary and quaternary Cu-based shape memory alloys

Superelasticity is a characteristic thermomechanical property in shape memory alloys (SMA), which is due to a reversible stress-induced martensitic transformation. Nano-compression experiments made possible the study of this property in Cu-Al-Ni SMA micropillars, showing an outstanding ultra-high mechanical damping capacity reproducible for thousands of cycles and reliable over the years. This scenario motivated the present work, where a comparative study of the damping capacity on four copper-based SMA: Cu-Al-Ni, Cu-Al-Be, Cu-Al-Ni-Be and Cu-Al-Ni-Ga is approached. For this purpose, [001] oriented single crystal micropillars of comparable dimensions (around 1 mu m in diameter) were milled by focused ion beam technique. All micropillars were cycled up to two hundred superelastic cycles, exhibiting a remarkable reproducibility. The damping capacity was evaluated through the dimensionless loss factor eta, calculated for each superelastic cycle, representing the dissipated energy per cycle and unit of volume. The calculated loss factor was averaged between three micro-pillars of each alloy, obtaining the following results: Cu-Al-Ni eta = 0.20 +/- 0.01; Cu-Al-Be eta = 0.100 +/- 0.006; Cu-Al-Ni-Be eta = 0.072 +/- 0.004 and Cu-Al-Ni-Ga eta = 0.042 +/- 0.002. These four alloys exhibit an intrinsic superelastic damping capacity and offer a wide loss factor band, which constitutes a reference for engineering, since this kind of micro/nano structures can potentially be integrated not only as sensors and actuators but also as dampers in the design of MEMS to improve their reliability. In addition, the study of the dependence of the superelastic loss factor on the diameter of the pillar was approached in the Cu-Al-Ni-Ga alloy, and here we demonstrate that there is a size effect on damping at the nanoscale.This research was supported by the Spanish Ministry of Economy and Competitiveness, MINECO, projects MAT2017-84069P and CONSOLIDER-INGENIO 2010 CSD2009-00013, as well as by the ELKARTEK-CEMAP project from the Industry Department of the Basque Government, and GIU-17/071 from the University of the Basque Country UPV/EHU, Spain. This work made use of the FIB and ICP facilities of the SGIKER from the UPV/EHU. The author V.F. acknowledges the Post-Doctoral Mobility Grant from the CONICET of Argentina, and J.F.G.-C. also acknowledges the Post-Doctoral Grant (ESPDOC18/37) from the UPV/EHU

Propuesta de ruta de degradación del BPA durante la reacción del ozono

Endocrine-disrupting compounds (EDC) are present in surface water bodies that supply water to the population. One of them is bisphenol A (BPA), which is listed as a carcinogen. This research addresses its degradation through the ozone reaction and presents a likely pathway established by analyzing products and degradation products using gas chromatography-mass spectrometry (GC-MS). BPA degradation was carried out under pseudo-first-order conditions, where liquid phase ozone was the limiting reactive, in doses of ≈2.29 × 10-4 M and BPA doses of 1.25 × 10-4, 17.5 × 10-4, and 35.0 × 10-4 M, looking to have molar ratios [BPA]> [O3]; the oxidation reaction was carried out in a stopped-flow system that allows obtaining results in the order of seconds. The degradation pathway obtained shows the rupture of one of the benzene rings, decreasing the phenolic toxicity of the BPA compound. The proposed pathway can contribute to the understanding of the degradation of BPA in the environment and tertiary treatment processes with the use of ozone. Likewise, it is intended to contribute with new data to the issues of drinking water treatment to offer safe water to the population

Pathogenic hantaviruses, northeastern Argentina and eastern Paraguay

Fil: Padula, Paula. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Virología. Laboratorio de Hantavirus; Argentina.Fil: Martínez, Valeria Paula. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas; Argentina.Fil: Bellomo, Carla. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas; Argentina.Fil: Maidana, Silvina. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas; Argentina.Fil: San Juan, Jorge. Hospital de Enfermedades Infecciosas “Francisco J. Muñiz,”; Argentina.Fil: Tagliaferri, Paulina. Hospital de Pediatría de Posadas; Argentina.Fil: Bargardi, Severino. Universidad Nacional de Misiones; Argentina.Fil: Vazquez, Cynthia. Laboratorio Central de Salud Pública; Paraguay.Fil: Colucci, N. Colucci, N. Ministerio de Salud Pública y Bienestar Social. Laboratorio Central de Salud Pública; Paraguay.Fil: Estévez, Julio. Ministerio de Salud Pública Provincial, Misiones; Argentina.Fil: Almirón, María. Instituto de Investigaciones en Ciencias de la Salud; Paraguay.We describe the first, to our knowledge, cases of hantavirus pulmonary syndrome in northeastern Argentina and eastern Paraguay. Andes and Juquitiba (JUQ) viruses were characterized. JUQV was also confi rmed in 5 Oligoryzomys nigripes reservoir species from Misiones. A novel Akodonborne genetic hantavirus lineage was detected in 1 rodent from the Biologic Reserve of Limoy

Pathogenic hantaviruses, northeastern Argentina and eastern Paraguay

Fil: Padula, Paula. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Virología. Laboratorio de Hantavirus; Argentina.Fil: Martínez, Valeria Paula. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas; Argentina.Fil: Bellomo, Carla. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas; Argentina.Fil: Maidana, Silvina. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas; Argentina.Fil: San Juan, Jorge. Hospital de Enfermedades Infecciosas “Francisco J. Muñiz,”; Argentina.Fil: Tagliaferri, Paulina. Hospital de Pediatría de Posadas; Argentina.Fil: Bargardi, Severino. Universidad Nacional de Misiones; Argentina.Fil: Vazquez, Cynthia. Laboratorio Central de Salud Pública; Paraguay.Fil: Colucci, N. Colucci, N. Ministerio de Salud Pública y Bienestar Social. Laboratorio Central de Salud Pública; Paraguay.Fil: Estévez, Julio. Ministerio de Salud Pública Provincial, Misiones; Argentina.Fil: Almirón, María. Instituto de Investigaciones en Ciencias de la Salud; Paraguay.We describe the first, to our knowledge, cases of hantavirus pulmonary syndrome in northeastern Argentina and eastern Paraguay. Andes and Juquitiba (JUQ) viruses were characterized. JUQV was also confi rmed in 5 Oligoryzomys nigripes reservoir species from Misiones. A novel Akodonborne genetic hantavirus lineage was detected in 1 rodent from the Biologic Reserve of Limoy

Elucidating the real-time Ag nanoparticle growth on a-Ag2WO4 during electron beam irradiation: experimental evidence and theoretical insights

Why and how Ag is formed when electron beam irradiation takes place on α-Ag2WO4 in a vacuum transmission electron microscopy chamber? To find an answer, the atomic-scale mechanisms underlying the formation and growth of Ag on α-Ag2WO4 have been investigated by detailed in situ transmission electron microscopy (TEM) and field emission scanning electron microscopy (FE-SEM) studies, density functional theory based calculations and ab initio molecular dynamics simulations. The growth process at different times, chemical composition, size distribution and element distribution were analyzed in depth at the nanoscale level using FE-SEM, operated at different voltages (5, 10, 15, and 20 kV), and TEM with energy dispersive spectroscopy (EDS) characterization. The size of Ag nanoparticles covers a wide range of values. Most of the Ag particles are in the 20–40 nm range. The nucleation and formation of Ag on α-Ag2WO4 is a result of structural and electronic changes in the AgOx (x = 2,4, 6, and 7) clusters used as constituent building blocks of this material, consistent with metallic Ag formation. First principle calculations point out that Ag-3 and Ag-4-fold coordinated centers, located in the sub-surface of the (100) surface, are the most energetically favorable to undergo the diffusion process to form metallic Ag. Ab initio molecular dynamics simulations and the nudged elastic band (NEB) method were used to investigate the minimum energy pathways of these Ag atoms from positions in the first slab layer to outward sites on the (100) surface of α-Ag2WO4. The results point out that the injection of electrons decreases the activation barrier for this diffusion step and this unusual behavior results from the presence of a lower energy barrier process.Generalitat-Valenciana: Prometeo/2009/053 Ministerio de Economia y Competitividad (Spain): CTQ2012-36253-C03-02 Spanish Brazilian program: PHB2009-0065-PC FAPESP : 2013/07296-2, 2012/14468-1, 2010/16970-0, 2013/02032-7. CAPES CNPq : 573636/2008-7, 150753/2013-6. CAPES : 088/201