144 research outputs found

    Chinchilla lanigera (Molina 1782) and C. chinchilla (Lichtenstein 1830): review of their distribution and new findings

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    Chinchilla lanigera (Molina, 1782) y C. chinchilla (Lichtenstein, 1830): revisión de su distribución y nuevas observaciones Tanto Chinchilla chinchilla como C. lanigera estuvieron muy cerca de la extinción debido a la caza histórica y masiva de que fueron objeto, y que acabó con millones de ejemplares durante la primera parte del siglo veinte. Para determinar el rango de distribución de estas especies y localizar nuevas colonias, analizamos las publicaciones científicas, los informes técnicos, la información facilitada por personas residentes y los trampeos en vivo. Detectamos una nueva colonia silvestre de pequeño tamaño de C. lanigera en la región de Atacama, Chile. El estado de conservación de ambas especies sería de “en grave peligro de extinción”, ya que la distribución está muy fragmentada y la mayor parte de las colonias detectadas son pequeñas y están aisladas.Millions of Chinchilla chinchilla and C. lanigera were killed during the early twentieth century and they were nearly hunted to extinction. In order to establish the current range of distribution of these two wild species and to localize possible new colonies, we used the available scientific literature, technical reports, information from residents, and live trapping methods. Both species are ‘critically endangered’ since their current distribution is highly fragmented and all recognized colonies are small and isolated. We report a small new wild colony of C. lanigera in the Atacama region, Chile.Chinchilla lanigera (Molina, 1782) y C. chinchilla (Lichtenstein, 1830): revisión de su distribución y nuevas observaciones Tanto Chinchilla chinchilla como C. lanigera estuvieron muy cerca de la extinción debido a la caza histórica y masiva de que fueron objeto, y que acabó con millones de ejemplares durante la primera parte del siglo veinte. Para determinar el rango de distribución de estas especies y localizar nuevas colonias, analizamos las publicaciones científicas, los informes técnicos, la información facilitada por personas residentes y los trampeos en vivo. Detectamos una nueva colonia silvestre de pequeño tamaño de C. lanigera en la región de Atacama, Chile. El estado de conservación de ambas especies sería de “en grave peligro de extinción”, ya que la distribución está muy fragmentada y la mayor parte de las colonias detectadas son pequeñas y están aisladas

    Aging of materials at inlet and outlet fuel manifolds in a SOFC stack

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    Analyses performed on a stack operated for more than 4000h at 750\ub0C at high fuel utilization (80%) revealed significant differences in aging behaviour of stack components when comparing fuel inlet and fuel outlet areas. Two samples were cut from the fuel inlet and outlet manifolds of the operated SOFC stack. The glass-ceramic sealing material and the interconnect alloy were exposed to a dual atmosphere (external air and internal fuel stream). The fuel composition was dry H2/N2 (60:40 vol. %) at the inlet and H2O/H2/N2 (48:12:40 vol. %) at the outlet. The stack was operated in co-flow configuration, with a large excess of air. It was found that the interfaces between the seal and the alloy were significantly affected by the difference in fuel composition. The sealant exposed to the outgoing air was significantly polluted by chromium generated in the stack and transported by the air stream. These investigations therefore reveal that the long-term evolution of the sealing and of the metallic support depends on the local conditions in the stack, as well as on additional interactions with other degradation phenomena

    Accelerated Stress Tests for Solid Oxide Cells via Artificial Aging of the Fuel Electrode

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    Solid Oxide Cells (SOCs) are under intensive development due to their great potential to meet the 2030 targets for decarbonization. One of their advantages is that they can work in reversible mode. However, in respect to durability, there are still some technical challenges. Although the quick development of experimental and modeling approaches gives insight into degradation mechanisms, an obligatory step that cannot be avoided is the performance of long‐term tests. Taking into account the target for a commercial lifetime is 80,000 h, experiments lasting years are not acceptable for market needs. This work aims to develop accelerated stress tests (ASTs) for SOCs by the artificial aging of the fuel electrode via redox cycling, which follows the degradation processes of calendar aging (Ni coarsening and migration). However, it can cause irreversible damage by the formation of cracks at the interface anode/electrolyte. The advantages of the developed procedure are that it offers a mild level of oxidation, which can be governed and regulated by the direct impedance monitoring of the Ni network resistance changes during oxidation/reduction on a bare anode sample. Once the redox cycling conditions are fixed and the anode/electrolyte sample is checked for cracks, the procedure is introduced for the AST in full‐cell configuration. The developed methodology is evaluated by a comparative analysis of current voltage and impedance measurements of pristine, artificially aged, and calendar‐aged button cells, combined with microstructural characterization of their anodes. It can be applied in both fuel cell and electrolyzer mode. The results obtained in this study from the electrochemical tests show that the artificially aged experimental cell corresponds to at least 3500 h of nominal operation. The number of hours is much bigger in respect to the microstructural aging of the anode. Taking into consideration that the duration of the performed 20 redox cycles is about 50 to 60 working hours, the acceleration factor in respect to experimental timing is estimated to be higher than 60, without any damaging of the sample. This result shows that the selected approach is very promising for a large decrease in testing times for SOCs

    Electrochemical testing of an innovative dual membrane fuel cell design in reversible mode

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    Solid oxide fuel Cells (SOFC) are intrinsically reversible which makes them attractive for the development of reversible devices (rSOC). The main hurdles that have to be overcome are the higher degradation in electrolyzer (EL) mode and the slow and difficult switching form mode to mode. This work aims at the development and experimental validation of a concept for rSOC based on a new dual membrane fuel cell (dmFC) design which can overcome the existing problems of the classical SOFC. The kernel of the system is additional chamber - central membrane (CM) for water formation/evacuation in FC mode and injection in El mode. Its optimization in respect of microstructure and geometry in laboratory conditions is carried out on button cells. The electrochemical performance is evaluated based on volt-ampere characteristics (VACs) combined with impedance measurements in different working points. The influence of a catalyst in the water chamber is also examined. The VACs which give integral picture of the cell performance are in excellent agreement with the impedance studies which ensure deeper and quantitative information about the processes, including information about the rate limiting step. The results from the optimization of the water chamber show that the combination of design and material brings to important principle advantages in respect to the classical rSOC \u2013 better performance in electrolyzer mode combined with instantaneous switching

    Andean Land Use And Biodiversity: Humanized Landscapes In A Time Of Change

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    Some landscapes Cannot be understood without reference., to the kinds. degrees, kinds, degrees, and history of human-caused modifications to the Earth's surface. The tropical latitudes of the Andes represent one such place, with agricultural land-use systems appearing in the Early Holocene. Current land use includes both intensive and extensive grazing and crop- or tree-based agricultural systems found across virtually the, entire range of possible elevations and humidity regimes. Biodiversity found in or adjacent to such humanized landscapes will have been altered in abundance. composition, and distribution in relation to the resiliency of the native Species to harvest, hold cover modifications, and other deliberate or inadvertent human land uses. In addition, the geometries of land cover, resulting flout difference among the shapes, sizes, connectivities, and physical structures of the patches, corridors, and matrices that compose landscape mosaics, will constrain biodiversity, often in predictable ways. This article proposes a conceptual model that alter ins that the Continued persistence of native species may depend as much oil the shifting Of Andean landscape mosaics as on species characteristics, themselves. Furthermore, mountains such as the Andes display long gradients of environmental Conditions that after in relation to latitude, soil moisture, aspect, and elevation. Global environmental change will shift these, especially temperature and humidity regimes along elevational gradients, causing Changes outside the historical range of variation for some species. Both land-use systems and Conservation efforts will need to respond spatially to these shifts in the future, at both landscape and regional scales.Geography and the Environmen

    Electrochemical performances and post-operational characterization of a segmented sofc operated under load for 15k hours

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    In the frame of the ENDURANCE FCH-JU-FP7 project (2014-2017) a segmented cell (20 segments regularly distributed from fuel inlet to fuel outlet) was operated for 15k hours in co-flow at 750\ub0C (average temperature) in hydrogen under load. Each segment was carefully monitored during operation by periodically acquiring the impedance spectra and constantly checking the voltage under current load. After 15k hours of operation the test was stopped and the cell used for further investigations in order to compare the cell evolution with the segment degradation. The overall observation in cross section of the cell has shown a good stability, however some differences were observed in the electrodes that might be related to the local operating conditions: temperature, H2 /H2O ratio in the fuel stream. The gathered results will contribute to increase the understanding the evolution of a SOFC in real operating conditions. Evidences of the effect of temperature, time and fuel pollutants were found

    Estudio comparativo de superficies colectoras y cubiertas transparentes

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    Se exponen los resultados del estudio comparativo de dos superficies colectoras distintas: aluminio arenado y hierro galvanizado pintado de negro, como así también de dos cubiertas transparentes: vidrio y policarbonato alveolar. El objeto del estudio era determinar la conveniencia de utilizar una u otra en la construcción de colectores solares de bajo costo. Para ello se construyeron dos colectores idénticos de 0,5 m2 de superficie colectora cada uno y con placa colectora y cubierta transparente fáciles de remover. Los ensayos se realizaron manteniendo las mismas condiciones en ambos colectores y alterando una sola variable a la vez: en primera instancia, con igual cubierta transparente se ensayaron dos placas colectoras distintas, y en segundo lugar, con igual placa colectora se usaron cubiertas transparentes distintas. Se midieron temperaturas de aire a la entrada y salida en cada colector, como así también en la placa colectora. Los resultados muestran idéntico comportamiento del policarbonato respecto del vidrio y un mejor comportamiento del hierro pintado respecto del aluminio arenado.Results of comparative studies of two different collector surfaces are exposed: treated aluminium and black painted galvanised iron, as well as two transparent coverplates: glass and polycarbonate. The object of study was to determinate the convenience of using each one in low cost solar collectors construction. Two identical collectors of 0,5 m2 surface each were built, with easy removable absorber and coverplate. The experiments were made maintaining the same conditions in both collectors and changing only one variable at once: firstly, two different absorbers were tested with the same coverplate, and in second place, two different coverplates were used with the same absorber. Temperatures of air at entrance and exit of each collector were measured, as well as absorber’s temperature. Results show identical behaviour of polycarbonate and glass, and a better performance of black painted iron over treated aluminium.Tema 8: Evaluación energética, instrumentación y materiales usados en energías renovables, modelización y simulación.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

    Estudio comparativo de superficies colectoras y cubiertas transparentes

    Get PDF
    Se exponen los resultados del estudio comparativo de dos superficies colectoras distintas: aluminio arenado y hierro galvanizado pintado de negro, como así también de dos cubiertas transparentes: vidrio y policarbonato alveolar. El objeto del estudio era determinar la conveniencia de utilizar una u otra en la construcción de colectores solares de bajo costo. Para ello se construyeron dos colectores idénticos de 0,5 m2 de superficie colectora cada uno y con placa colectora y cubierta transparente fáciles de remover. Los ensayos se realizaron manteniendo las mismas condiciones en ambos colectores y alterando una sola variable a la vez: en primera instancia, con igual cubierta transparente se ensayaron dos placas colectoras distintas, y en segundo lugar, con igual placa colectora se usaron cubiertas transparentes distintas. Se midieron temperaturas de aire a la entrada y salida en cada colector, como así también en la placa colectora. Los resultados muestran idéntico comportamiento del policarbonato respecto del vidrio y un mejor comportamiento del hierro pintado respecto del aluminio arenado.Results of comparative studies of two different collector surfaces are exposed: treated aluminium and black painted galvanised iron, as well as two transparent coverplates: glass and polycarbonate. The object of study was to determinate the convenience of using each one in low cost solar collectors construction. Two identical collectors of 0,5 m2 surface each were built, with easy removable absorber and coverplate. The experiments were made maintaining the same conditions in both collectors and changing only one variable at once: firstly, two different absorbers were tested with the same coverplate, and in second place, two different coverplates were used with the same absorber. Temperatures of air at entrance and exit of each collector were measured, as well as absorber’s temperature. Results show identical behaviour of polycarbonate and glass, and a better performance of black painted iron over treated aluminium.Tema 8: Evaluación energética, instrumentación y materiales usados en energías renovables, modelización y simulación.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

    Mitochondrial phylogeography and demographic history of the Vicuña: implications for conservation

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    The vicuña (Vicugna vicugna; Miller, 1924) is a conservation success story, having recovered from near extinction in the 1960s to current population levels estimated at 275 000. However, lack of information about its demographic history and genetic diversity has limited both our understanding of its recovery and the development of science-based conservation measures. To examine the evolution and recent demographic history of the vicuña across its current range and to assess its genetic variation and population structure, we sequenced mitochondrial DNA from the control region (CR) for 261 individuals from 29 populations across Peru, Chile and Argentina. Our results suggest that populations currently designated as Vicugna vicugna vicugna and Vicugna vicugna mensalis comprise separate mitochondrial lineages. The current population distribution appears to be the result of a recent demographic expansion associated with the last major glacial event of the Pleistocene in the northern (18 to 22°S) dry Andes 14–12 000 years ago and the establishment of an extremely arid belt known as the 'Dry Diagonal' to 29°S. Within the Dry Diagonal, small populations of V. v. vicugna appear to have survived showing the genetic signature of demographic isolation, whereas to the north V. v. mensalis populations underwent a rapid demographic expansion before recent anthropogenic impacts

    Socio-environmental impacts of non-native and transplanted aquatic mollusc species in South America: What do we really know?

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    The impacts of biological invasions remain poorly known for some habitats, regions and taxa. To date, there has been no comprehensive effort to review and synthesize the impacts of invasive mollusc species in South America. In this paper, we provide a synoptic view on what is known on documented socio-ecological impacts of aquatic no-native mollusc species (NNMS) and transplanted mollusc species (TMS) from South America. An expert group involving malacologists and taxonomists from different countries, the “South America Alien Molluscs Specialists” (eMIAS), shared and summarized the scientific literature, databases, and published and unpublished information on confirmed impacts of NNMS and TMS in South America. Three broad categories, non-mutually exclusive were used as a framework: “Environmental/Biodiversity impacts”, “Economic and social effects”, and “Human health impacts”. Some 21 NNMS and seven TMS have documented impacts on at least one of those three categories. We encourage targeting the less known areas of research, such as economic valuation of human health (and veterinary) impacts attributable to NNMS or TMS and expand our knowledge of environmental impacts for the species listed in this study.Fil: Carranza, Alvar. Universidad de la República; Uruguay. Museo Nacional de Historia Natural Uruguay; UruguayFil: Agudo Padrón, Ignacio. Projeto “avulsos Malacológicos”; BrasilFil: Collado, Gonzalo A.. Universidad del Bio Bio; Chile. Sociedad Malacológica Chile; ChileFil: Damborenea, Maria Cristina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología Invertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Fabres, Alejandra. Sociedad Malacológica Chile; Chile. Universidad Católica de Maule; ChileFil: Gutierrez Gregoric, Diego Eduardo. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología Invertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Lodeiros, Cesar. Universidad Técnica de Manabí; Ecuador. Universidad de Oriente; VenezuelaFil: Ludwig, Sandra. Universidade Federal de Minas Gerais; BrasilFil: Pastorino, Roberto Santiago Guido. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Penchaszadeh, Pablo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Salvador, Rodrigo B.. Museum of New Zealand Te Papa Tongarewa,; Nueva Zelanda. The Artic University of Norway; NoruegaFil: Spotorno, Paula. Universidade Federal do Rio Grande; BrasilFil: Thiengo, Silvana. Fundación Oswaldo Cruz; BrasilFil: Vidigal, Teofania Heloisa Dutra Amorim. Universidade Federal de Minas Gerais; BrasilFil: Darrigran, Gustavo Alberto. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División de Zoología Invertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin
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