Atributos químicos do solo em sistemas agrossilvipastoris do semiárido cearense com a presença do fogo.

Resumo: A análise dos atributos químicos do solo é uma importante ferramenta para se conhecer a qualidade e as deficiências do solo. Objetivou-se avaliar a fertilidade do solo sob Luvissolo Crômico Órtico e Luvissolo Hipocrômico Órtico em sistema agrossilvipastoril. O presente trabalho foi realizado na Embrapa Caprinos e Ovinos, os sistemas avaliados consistiam de diferentes tipos de manejo: agrosilvipastoril, silvipastoril com queima, silvipastoril sem queima, mata nativa com queima, mata nativa sem queima e sistema tradicional. O delineamento foi inteiramente casualizado em parcelas subdivididas, sendo as parcelas, os manejos e as subparcelas as profundidades (0-0,10 e 0,10-0,20 m); com cinco repetições. Houve diferença significativa nos diferentes manejos para todo os atributos químicos, exceto Mg, Al e V. Os ambientes silvipastoril com e sem queima apresentaram maiores valores para os atributos químicos em relação ao sistema tradicional. Os manejos silvipastoril sem e com queima proporcionaram as maiores concentrações para pH e K; e P, Ca e Na, respectivamente. O manejo agrossilvipastoril apresentou os maiores valores para pH, Na e C.E. Para manta nativa sem e com queima, as maiores concentrações foram para M.O., Ntotal, K, C.E., e adicionalmente para a mata sem queima H+Al. O sistema tradicional apresentou maiores concentrações para Na. A camada superior apresentou maiores valores para pH, M.O., Ntotal, K, CTC e CE em relação a camada 0,10-0,20 m. [Soil chemical properties in agrosylvopasture system at semi-arid northeastern Brazil with presence of fire]. Abstract: The analysis of soil chemical properties is an important tool to know the quality and soil deficiencies. The present study which was conducted at Embrapa Goats e Sheeps had as objective to evaluate soil fertility under Luvisols in agrosilvopasture system in a semi-arid zone. The following treatments were evaluated: agrosilvopasture, burnt silvopasture, non-burnt silvopasture, burnt native forest, non-burnt native forest and traditional. The experimental design was completely randomized block with split plots. The plots, the managements, the subplots and the depths (0-0.10 and 0.10-0.20 m) had five replications. There were significant difference in all treatments for all chemical attributes except Mg, Al and V. The treatments burnt and non-burnt silvopasture and agrosilvopasture showed high values for chemical attributes in relation to the traditional system. The agrosilvopasture environment had higher values for pH, Na and EC. As for burnt and non-burnt native vegetation, both had the highest concentration for MO, Ntotal, K, and EC. Besides, the non-burnt native vegetation had the highest concentration for H+Al. The traditional treatment had high concentration of Na. The top layer had higher values for pH, organic matter, total N, K, CEC and EC compared to 0.10-0.20 m layer

Radial abundance gradients in the outer Galactic disk as traced by main-sequence OB stars

Using a sample of 31 main-sequence OB stars located between galactocentric distances 8.4 - 15.6 kpc, we aim to probe the present-day radial abundance gradients of the Galactic disk. The analysis is based on high-resolution spectra obtained with the MIKE spectrograph on the Magellan Clay 6.5-m telescope on Las Campanas. We used a non-NLTE analysis in a self-consistent semi-automatic routine based on TLUSTY and SYNSPEC to determine atmospheric parameters and chemical abundances. Stellar parameters (effective temperature, surface gravity, projected rotational velocity, microturbulence, and macroturbulence) and silicon and oxygen abundances are presented for 28 stars located beyond 9 kpc from the Galactic centre plus three stars in the solar neighborhood. The stars of our sample are mostly on the main-sequence, with effective temperatures between 20800 - 31300 K, and surface gravities between 3.23 - 4.45 dex. The radial oxygen and silicon abundance gradients are negative and have slopes of -0.07 dex/kpc and -0.09 dex/kpc, respectively, in the region $8.4 \leq R_G \leq 15.6$\,kpc. The obtained gradients are compatible with the present-day oxygen and silicon abundances measured in the solar neighborhood and are consistent with radial metallicity gradients predicted by chemodynamical models of Galaxy Evolution for a subsample of young stars located close to the Galactic plane.Comment: Accepted for publication in the A&

Possible unconventional superconductivity in substituted BaFe2_{2}As2_{2} revealed by magnetic pair-breaking studies

The possible existence of a sign-changing gap symmetry in BaFe$_{2}$As$_{2}$-derived superconductors (SC) has been an exciting topic of research in the last few years. To further investigate this subject we combine Electron Spin Resonance (ESR) and pressure-dependent transport measurements to investigate magnetic pair-breaking effects on BaFe$_{1.9}M_{0.1}$As$_{2}$ ($M=$ Mn, Co, Cu, and Ni) single crystals. An ESR signal, indicative of the presence of localized magnetic moments, is observed only for $M=$ Cu and Mn compounds, which display very low SC transition temperature ($T_{c}$) and no SC, respectively. From the ESR analysis assuming the absence of bottleneck effects, the microscopic parameters are extracted to show that this reduction of $T_{c}$ cannot be accounted by the Abrikosov-Gorkov pair-breaking expression for a sign-preserving gap function. Our results reveal an unconventional spin- and pressure-dependent pair-breaking effect and impose strong constraints on the pairing symmetry of these materials

Extração e quantificação simultânea de polifenoloxidases de extratos proteicos solúveis e insolúveis de folhas.

Procedimento para a extração e quantificação de PFOs em folhas; Recomendações importantes para a execução do protocolo de dosagem de PFOs.bitstream/item/53725/1/COT146.pd