Influence of Si and Ge Microalloying Additions and Plastic Deformation on Precipitation Processes in Al-Cu Based Alloys

The combined effect of micro-alloying with Si and Ge and/or plastic deformationprior to ageing at 160˚C on age hardening has been studied in an Al-2 at%Cu alloy. The results obtained indicate that the hardness response is faster and the peak hardness is higher when plastic deformation and micro-alloying are applied together than performing each procedure individually. Different amounts of deformation, ranging from 0% to 30% have been utilized. An optimum deformation degree for the hardening response has been established around 8%for the Al-Cu-Si-Ge alloy. Characterization by transmission electron microscopy(TEM) shows that the peak hardness is due to a complex microstructurethat contained θ ′′ disc shaped precipitates, rod-shaped Si-Ge precipitatesand θ ′ plates that were heterogeneously nucleated on the Si-Ge particles.Pre-deformation has been found to stimulate the growth of the θ ′ platesdue to enhanced diffusion along dislocation cores. Increasing deformationreduces the influence of the Si-Ge precipitates on heterogeneous nucleation, leading to reduced peak hardness and faster over-ageing.Fil: Castro Riglos, Maria Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comision Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Bariloche). División Física de Metales; ArgentinaFil: Tolley, Alfredo Juan. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comision Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Bariloche). División Física de Metales; Argentin

Crónicas de un proyecto tecnológico en un Instituto del CONICET: la Planta Modelo Experimental de Agua Pesada (INTEC/INGAR)

Tomé contacto por primera vez con el Instituto para el Desarrollo Tecnológico de la Industria Química (en adelante INTEC), a principios de 2009 cuando –por cuestiones laborales– debí entrevistar a un investigador que, a priori, allí se desempeñaba. Fui citada en el edificio que el instituto tiene en la calle Güemes, en el centro de la ciudad de Santa Fe. Luego de realizar mi entrevista, el investigador me ofreció hacer una visita a su instituto y me condujo dos cuadras hasta otro edificio, perteneciente en realidad al Instituto de Desarrollo y Diseño (en adelante INGAR). Dada mi confusión, pregunté sobre la filiación institucional de mi anfitrión a lo que respondió: somos como una gran familia, muchos investigadores de INGAR eran antes del INTEC. Él pertenecía, en realidad, al INGAR. Sus palabras hicieron eco cuando, en 2013, ingresé como personal administrativo del CONICET en el INTEC y el entonces director me dijo Te vas a sentir como en tu casa, acá nos conocemos todos para darme la bienvenida. Meses más tarde, escuché a un investigador del INTEC argumentaba, en contra de una mudanza programada, que ese edificio había sido su casa. Ahora bien este investigador no solo explicitó, en su argumentación contra la mudanza, un fuerte arraigo y sentido de pertenencia respecto del espacio físico de su lugar de trabajo, también avanzó en conectar ese espacio con el pasado de la institución. Porque con ese espacio físico que él defendía se reconocía todo lo que el Dr. Cassano había hecho por ellos y por ese instituto, agregaba asociando el edificio a un pasado específico –el pasado fundacional– y a la figura del fundador.Fil: Castro, Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Vulnerable Populations and Flooding: A Bay Area County Public Alert and Warning Case Study

Public alert and warning systems are crucial tools that save lives and protect property in times of emergencies. In the past several decades, natural disasters have struck the nation, and effective public alerts and warnings were not disseminated to all impacted populations, calling into question the effectiveness of emergency communication systems (Wimberley, 2012). As an example, in 2012, when Hurricane Sandy hit the east coast, public alert and warning systems reached those who had access to technological devices. However, emergency managers and alerting authorities faced the challenge of alerting all groups, including the homeless and individuals with access and functional needs, who may not have access to traditional communication methods like television and radio broadcast stations, cell phones, or landlines. In addition, individuals who experience language barriers and limited English language proficiency struggle to fully understand public alerts (Wimberly, 2012). Locally, emergency and disaster communications have also left some of the most vulnerable populations behind. In 2017, the Coyote Creek flood in Santa Clara County devastated the City of San José. The flooding disproportionately impacted several low-income communities and households with little English proficiency, and there was limited communication between the agencies involved and the communities affected (Wadsworth et al., 2017; Wadsworth and Koehn, 2017). A history of inadequate emergency communications and floodplain mismanagement, and a lack of communication between the City of San José and the Santa Clara Valley Water District, contributed to the disaster (Rogers, 2017), and in February 2017, two consecutive atmospheric rivers led to severe flooding. The Anderson Dam, which is a reservoir, not a flood control dam, - had reached capacity and began to overflow. This event forced 14,000 residents out of their homes, with little time to evacuate (Rogers, 2017). By July 2017, there were still an estimated 200 residents that had not been able to return to their homes and were living in temporary housing (Sykes, 2017). The flooding was particularly devastating in low-income Vietnamese and Hispanic households, and mobile home parks, where there were many senior citizens and/or people with limited English proficiency (Wadsworth et al., 2017; Wadsworth and Koehn, 2017). Improved emergency communications could have provided an opportunity to warn residents and provide notice about the evacuation in multiple languages, which could have potentially avoided the substantial property damage, and the emotional distress caused by prolonged displacement (Alexander, 2020; Sykes, 2017). Drawing from these disasters, this research analyzed how four Bay Area counties issue public warnings, with a particular focus on how they engaged vulnerable populations during crisis communication. By exploring this facet of crisis communication, this research proposes potential solutions to improve communication and engagement with vulnerable populations

Efecto de la sequía continua y la inmersión sobre la respuesta de eclosión de los huevos de Ochlerotatus albifasciatus (Diptera: Culicidae) almacenados a baja temperatura

Se estudió el rol de los factores ambientales sobre la eclosión de los huevos de O. albifasciatus (Macquart), simulando condiciones de invierno. La hipótesis planteada fue que la respuesta de eclosión de los huevos depende de: (1) tiempo de permanencia a baja temperatura, (2) condiciones de almacenamiento, y (3) tiempo de aclimatación. Los huevos fueron almacenados a 5º C en condiciones de sequía y sumergidos durante 7, 21, 35, 90 y 146 días; luego fueron aclimatados a 22º C durante 24, 72, y 168 horas y posteriormente inundados para inducir la eclosión. El porcentaje de huevos eclosionados se analizó con un Modelo Lineal Generalizado con distribución binomial. Los resultados mostraron que: (1) largos períodos de almacenamiento en frío y largos tiempos de aclimatación mejoran la respuesta de eclosión, (2) la condición de almacenamiento tiene un efecto moderado en la eclosión, siendo más marcada en los huevos almacenados en seco; (3) tiempos prolongados de aclimatación mejoran aún más las eclosiones de los huevos sumergidos, que los almacenados en seco; (4) largo tiempo en frío mejora la eclosión de los huevos almacenados en seco, que los sumergidos; (5) los huevos que permanecieron más tiempo en frío respondieron mejor cuando el tiempo de aclimatación fue prolongado.The role of environmental factors on the hatching response of O. albifasciatus (Macquart) eggs is studied by simulating winter conditions in the laboratory. The hypothesis tested was that hatching response is affected by: (1) time that eggs remain at low temperature, (2) storage conditions, and (3) acclimatization time. Eggs were stored at 5ºC in drought and immersion conditions during 7, 21, 35, 90 and 146 days, immediately after, they were acclimatized at 22ºC during 24, 72, and 168 hours, and then eggs were flooded to induce hatching. Percent of hatched eggs was analyzed with a Generalized Lineal Model with a binomial distribution. Results show that: (1) a long storage period at cold temperature and long acclimatization periods improve the hatching response; (2) storage conditions have a moderate effect on hatching, being more evident in eggs stored dry; (3) a long time of acclimatization favors the hatching response in submerged eggs more than in eggs stored dry; (4) long time at cold favors the hatching response in eggs stored dry more than in submerged eggs; (5) the hatching response of eggs that remain for a long time at low temperature is higher when the time of acclimatization is long.Fil: Sy, Victoria Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología ; ArgentinaFil: Campos, Raul Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología ; ArgentinaFil: Castro, Luis Eduardo. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Significant hardness enhancement in an Al–Cu–Mg alloy with high Cu:Mg ratio by microalloying with Si and Ge

The evolution of hardness in an Al-Cu-Mg based alloy with high Cu:Mg ratio (= 2, at. %) microalloyed with Si and Ge was studied during artificial ageing treatment performed at 190 °C. The results were compared to those obtained in a similar alloy with no Mg content. The hardness evolution in the Mg containing alloy was similar to that of the Mg free alloy, but shifted by about 50 Hv to higher values for all ageing times. The peak hardness occurred after 3 h ageing in both alloys, with a value slightly above 200 Hv in the Mg containing alloy. The microstructure of the peak aged and the overaged condition were characterized by means of transmission electron microscopy (TEM). For the Mg-containing alloy the microstructure of the peak aged condition consisted of plate-shaped precipitates, with a very similar structure to that of the θ′ phase and a high density of small needle-shaped precipitates lying along the Al directions. In the peak aged and overaged conditions the needle-shaped precipitates were found to belong to the Q′ phase (Al4Cu2Mg8Si7) or its precursor phases, previously observed in the Al–Mg–Si system with minor Cu additions.Fil: Castro Riglos, Maria Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Morello, Nicolas. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Tolley, Alfredo Juan. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentin

Atacama en el tiempo. territorios, identidades, lenguas. (Provincia El Loa, II Región)

Se ofrece una perspectiva histórica sobre el tema de la construcción de identidades étnicas, desde la época prehispánica hasta el presente etnográfico, en los territorios de costa y tierras altas de la Región de Antofagasta y su dinámica con la vertiente oriental andina aledaña

Culture-Based Environmental Microbiology Monitoring of Crop-Based Space Food Systems (veggie Monitoring)

Crewmembers live and work in a closed environment that is monitored to ensure their health and safety. Quarterly monitoring of the microorganisms in the International Space Station (ISS) environment supports crew safety and contributes to a large set of microbial concentration and diversity data from air, surfaces and water samples. This study leverages quarterly operational Environmental Health System (EHS) sampling by collecting additional microbial samples from the surface of the stations Veggie plant production system. Longer exploration missions may require spaceflight-based systems for growth of plants, and this investigation is expected to provide additional data to help establish requirements to protect these systems, plants, and crew, mitigating adverse microbial exposure