460 research outputs found

    Toxicity of AMPA to the earthworm Eisenia andrei Bouché, 1972 in tropical artificial soil.

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    Aminomethylphosphonic acid (AMPA) - one of glyphosate's main metabolites - has been classified as persistent in soils, raising concern regarding the widespread use of glyphosate in agriculture and forestry. Glyphosate may have negative or neutral effects on soil biota, but no information is available on the toxicity of AMPA to soil invertebrates. Therefore our aim was to study the effect of AMPA on mortality and reproduction of the earthworm species Eisenia andrei using standard soil ecotoxicologica I methods (ISO). Field-relevant concentrations of AMPA had no significant effects on mortality in acute or chronic assays. Except at the highest concentration tested, a significant biomass loss was observed compared to controls in the chronic assay. The number of juveniles and cocoons increased with higher concentrations of AMPA applied, but their mean weights decreased. This mass loss indicates higher sensitivity of juveniles than adults to AMPA. Our results suggest that earthworms coming from parents grown in contaminated soils may have reduced growth, limiting their beneficial roles in key soil ecosystem functions. Nevertheless, further research is needed to better understand the mechanisms underlying the sublethal effects observed here

    Efeitos da temperatura na frigoconservação de pinhões.

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    O pinhão é um alimento de importância cultural, social e econômica principalmente na região sul do Brasil, sendo visto como uma alternativa para gerar renda, incentivar o plantio e a preservação do pinheiro-brasileiro. Sua comercialização e industrialização requerem definições de métodos para conservação pós-colheita, já que o período da coleta é limitado entre os meses de abril a agosto. A pós-colheita do pinhão é caracterizada pelo longo período de entressafra e breve vida de prateleira, que decorre de fatores intrínsecos (fisiologia recalcitrante; elevada umidade e atividade de água) e extrínsecos (ataques biológicos, broca-do-pinhão e fungos; e condições de armazenamento). Nesse estudo avaliou-se o efeito de diferentes temperaturas sobre a qualidade de pinhões armazenados em elevada UR (90 + 3 %) por 60 dias, e mais 3 dias de vida de prateleira. Os pinhões, em armazenamento refrigerado (AR), foram expostos às temperaturas de 20,0 ºC; 2,0 ºC; 1,0 ºC; 0,0 ºC e -0,5 ºC. Foram avaliadas a respiração, perda de massa, produção de etileno, cor e firmeza na saída da câmara fria e após 3 dias em temperatura ambiente. Tanto na saída da câmara fria como na vida de prateleira a maior taxa respiratória foi obtida a 20ºC, assim como a perda de massa e pinhões mais firmes, em decorrência da maior desidratação. Os pinhões não apresentaram produção de etileno em níveis detectáveis através de cromatografia gasosa. Em todas as amostras houve perda na coloração, entretanto, sem diferença significativa entre os tratamentos.Resumo

    Silicon Mie Resonators for Highly Directional Light Emission from monolayer MoS2

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    Controlling light emission from quantum emitters has important applications ranging from solid-state lighting and displays to nanoscale single-photon sources. Optical antennas have emerged as promising tools to achieve such control right at the location of the emitter, without the need for bulky, external optics. Semiconductor nanoantennas are particularly practical for this purpose because simple geometries, such as wires and spheres, support multiple, degenerate optical resonances. Here, we start by modifying Mie scattering theory developed for plane wave illumination to describe scattering of dipole emission. We then use this theory and experiments to demonstrate several pathways to achieve control over the directionality, polarization state, and spectral emission that rely on a coherent coupling of an emitting dipole to optical resonances of a Si nanowire. A forward-to-backward ratio of 20 was demonstrated for the electric dipole emission at 680 nm from a monolayer MoS2 by optically coupling it to a Si nanowire

    Igneous mineralogy at Bradbury Rise: The first ChemCam campaign at Gale crater

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    Textural and compositional analyses using Chemistry Camera (ChemCam) remote microimager and laser-induced breakdown spectroscopy (LIBS) have been performed on five float rocks and coarse gravels along the first 100 m of the Curiosity traverse at Bradbury Rise. ChemCam, the first LIBS instrument sent to another planet, offers the opportunity to assess mineralogic diversity at grain-size scales (~ 100 µm) and, from this, lithologic diversity. Depth profiling indicates that targets are relatively free of surface coatings. One type of igneous rock is volcanic and includes both aphanitic (Coronation) and porphyritic (Mara) samples. The porphyritic sample shows dark grains that are likely pyroxene megacrysts in a fine-grained mesostasis containing andesine needles. Both types have magnesium-poor basaltic compositions and in this respect are similar to the evolved Jake Matijevic rock analyzed further along the Curiosity traverse both with Alpha-Particle X-ray Spectrometer and ChemCam instruments. The second rock type encountered is a coarse-grained intrusive rock (Thor Lake) showing equigranular texture with millimeter size crystals of feldspars and Fe-Ti oxides. Such a rock is not unique at Gale as the surrounding coarse gravels (such as Beaulieu) and the conglomerate Link are dominated by feldspathic (andesine-bytownite) clasts. Finally, alkali feldspar compositions associated with a silica polymorph have been analyzed in fractured filling material of Preble rock and in Stark, a putative pumice or an impact melt. These observations document magmatic diversity at Gale and describe the first fragments of feldspar-rich lithologies (possibly an anorthosite) that may be ancient crust transported from the crater rim and now forming float rocks, coarse gravel, or conglomerate clasts

    Long-term results of radiotherapy for periarthritis of the shoulder: a retrospective evaluation

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    <p>Abstract</p> <p>Background</p> <p>To evaluate retrospectively the results of radiotherapy for periarthritis of the shoulder</p> <p>Methods</p> <p>In 1983–2004, 141 patients were treated, all had attended at least one follow-up examination. 19% had had pain for several weeks, 66% for months and 14% for years. Shoulder motility was impaired in 137/140 patients. Nearly all patients had taken oral analgesics, 81% had undergone physiotherapy, five patients had been operated on, and six had been irradiated. Radiotherapy was applied using regular anterior-posterior opposing portals and Co-60 gamma rays or 4 MV photons. 89% of the patients received a total dose of 6 Gy (dose/fraction of 1 Gy twice weekly, the others had total doses ranging from 4 to 8 Gy. The patients and the referring doctors were given written questionnaires in order to obtain long-term results. The mean duration of follow-up was 6.9 years [0–20 years].</p> <p>Results</p> <p>During the first follow-up examination at the end of radiotherapy 56% of the patients reported pain relief and improvement of motility. After in median 4.5 months the values were 69 and 89%, after 3.9 years 73% and 73%, respectively. There were virtually no side effects. In the questionnaires, 69% of the patients reported pain relief directly after radiotherapy, 31% up to 12 weeks after radiotherapy. 56% of the patients stated that pain relief had lasted for "years", in further 12% at least for "months".</p> <p>Conclusion</p> <p>Low-dose radiotherapy for periarthropathy of the shoulder was highly effective and yielded long-lasting improvement of pain and motility without side effects.</p
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