866 research outputs found

    Synthesis of high-oxidation Y-Ba-Cu-O phases in superoxygenated thin films

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    It is known that solid-state reaction in high-pressure oxygen can stabilize high-oxidation phases of Y-Ba-Cu-O superconductors in powder form. We extend this superoxygenation concept of synthesis to thin films which, due to their large surface-to-volume ratio, are more reactive thermodynamically. Epitaxial thin films of YBa2Cu3O7−δ\rm{YBa_2Cu_3O_{7-\delta}} grown by pulsed laser deposition are annealed at up to 700 atm O2_2 and 900∘^\circC, in conjunction with Cu enrichment by solid-state diffusion. The films show clear formation of Y2Ba4Cu7O15−δ\rm{Y_2Ba_4Cu_7O_{15-\delta}} and Y2Ba4Cu8O16\rm{Y_2Ba_4Cu_8O_{16}} as well as regions of YBa2Cu5O9−δ\rm{YBa_2Cu_5O_{9-\delta}} and YBa2_2Cu6_6O10−δ_{10-\delta} phases, according to scanning transmission electron microscopy, x-ray diffraction and x-ray absorption spectroscopy. Similarly annealed YBa2Cu3O7−δ\rm{YBa_2Cu_3O_{7-\delta}} powders show no phase conversion. Our results demonstrate a novel route of synthesis towards discovering more complex phases of cuprates and other superconducting oxides.Comment: Accepted for publication in Physical Review Material

    Associative learning in the cnidarian Nematostella vectensis.

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    The ability to learn and form memories allows animals to adapt their behavior based on previous experiences. Associative learning, the process through which organisms learn about the relationship between two distinct events, has been extensively studied in various animal taxa. However, the existence of associative learning, prior to the emergence of centralized nervous systems in bilaterian animals, remains unclear. Cnidarians such as sea anemones or jellyfish possess a nerve net, which lacks centralization. As the sister group to bilaterians, they are particularly well suited for studying the evolution of nervous system functions. Here, we probe the capacity of the starlet sea anemone Nematostella vectensis to form associative memories by using a classical conditioning approach. We developed a protocol combining light as the conditioned stimulus with an electric shock as the aversive unconditioned stimulus. After repetitive training, animals exhibited a conditioned response to light alone indicating that they learned the association. In contrast, all control conditions did not form associative memories. Besides shedding light on an aspect of cnidarian behavior, these results root associative learning before the emergence of NS centralization in the metazoan lineage and raise fundamental questions about the origin and evolution of cognition in brainless animals

    Produção orgânica de uva para mesa.

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    Avaliação da mortalidade através do contato de machos de Grapholita molesta (Lepidoptera, Tortricidae) com o produto Splat Cida Grafo Bona.

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    Este trabalho teve como objetivo avaliar a mortalidade de machos de Grapholita molesta por contato com o Splat Cida Grafo Bona

    Avaliação do raio de ação de armadilha Delta iscada com o feromônio sexual sintético de Grapholita molesta (Lepidoptera, Tortricidae), em pomares de pessegueiro.

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    Neste trabalho foi determinado o raio de ação do atrativo sexual de G. molesta (Iscalure Grapholita® ISCA Tecnologias) em armadilhas Delta, em pomares de pessegueiro

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    Infestações do ácaro Calepitrimerus vitis foram verificadas nas últimas safras nos parreirais do Sul do Brasil, entre os meses de dezembro e março. A espécie ataca somente videira e provoca deformações nas folhas, queda prematura e até mesmo atraso no desenvolvimento das plantas. A eliminação de restos de poda durante o inverno é importante esttratégia de controle, porque nesse período as fêmeas ficam alojadas nas reentrâncias dos ramos e no interior das brácteas das gemas
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