5 research outputs found

    Metodologia para teste de tetrazĂłlio em sementes de Amburana cearensis (AllemĂŁo) A.C. Smith

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    Objetivou-se com este trabalho estudar a metodologia do teste de tetrazĂłlio para sementes de Amburana cearensis (AllemĂŁo) A.C. Smith, determinando as melhores condiçÔes de prĂ©-umedecimento, bem como temperatura, perĂ­odo de coloração e concentração da solução de tetrazĂłlio. Avaliou-se a coloração das sementes intactas e escarificadas (lixadas), ambas com tegumento, diretamente na solução de tetrazĂłlio nas concentraçÔes de 0,025; 0,050; 0,075 e 1% a 35 e 40ÂșC, por 12 e 24h no escuro. Verificou-se o prĂ©-umedecimento para retirar o tegumento utilizando-se sementes intactas e escarificadas, as quais foram imersas diretamente em ĂĄgua e submetidas a embebição em papel toalha e por 12, 24, 36 e 48 horas em temperaturas de 35 e 40ÂșC. ApĂłs a determinação do mĂ©todo para retirar o tegumento os embriĂ”es foram submetidas Ă  coloração em solução de tetrazĂłlio nas concentraçÔes de 0,025; 0,050; 0,075 e 1%. Com os resultados obtidos verificou-se a necessidade da retirada total do tegumento para que ocorra a coloração e que a temperatura de 40ÂșC Ă© prejudicial para a embebição no prĂ©-umedecimento. O teste de tetrazĂłlio nas sementes de A. cearensis deve ser realizado com o prĂ©-umedecimento das sementes escarificadas (lixadas) e imersas diretamente em ĂĄgua por 24 horas, na temperatura de 35ÂșC, para posterior retirada total do tegumento. E para atingir a coloração ideal os embriĂ”es devem ser imersos em solução de tetrazĂłlio a 0,05% por 3 horas, a 40ÂșC

    Multi-messenger Observations of a Binary Neutron Star Merger

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    International audienceOn 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ∌1.7 s\sim 1.7\,{\rm{s}} with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg(2) at a luminosity distance of 40−8+8{40}_{-8}^{+8} Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26  M⊙\,{M}_{\odot }. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ∌40 Mpc\sim 40\,{\rm{Mpc}}) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ∌10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ∌9\sim 9 and ∌16\sim 16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta
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