Produtividade das matrizes e enraizamento de estacas de erva-mate.

Resumo

Sobrevivência de enxertos de araucária em viveiro com materiais genéticos de quatro estados.

A Araucaria angustifolia (Bert.) O. Ktze é uma espécie de grande importância socioeconômica e ambiental, especialmente na região Sul do Brasil. Nos últimos anos ganhou importância a clonagem da espécie com objetivo principal para produzir pinhões e viabilizar programas de melhormanento e conservação da espécie. Com a enxertia é possível reduzir de forma significativa o início da floração e com isso antecipação na produção de pinhões. O objetivo do trabalho foi avaliar a sobrevivência de enxertos por borbulhia de placa em viveiro, por meio de diferentes clones provenientes de quatro estados do Brasil: Minas Gerais, São Paulo, Paraná e Santa Catarina. O trabalho foi desenvolvido em estufa com cobertura plástica no viveiro do Centro de Pesquisa para Agricultura Familiar/Epagri/Cepaf/Chapecó, SC. Os porta-enxertos da araucária foram feitos por propagação seminal, produzidos em sacolas plásticas com aproximadamente cinco litros de volume, com substrato comercial florestal. No momento da enxertia, os porta-enxertos de aproximadamente 20 meses de idade, tinham alturas entre 0,8 m e 1,2 m e diâmetros no local da enxertia entre 8 mm e 15 mm. O material genético para a realização das enxertias foi coletado no jardim clonal da Embrapa Florestas, Colombo, PR, e acondicionado em caixas térmicas com gelo para o transporte. Para a realização dos enxertos foram utilizadas borbulhas de seis materiais genéticos do estado de Santa Catarina, sete do Paraná e três de cada estado de São Paulo e Minas Gerais. O método utilizado na enxertia foi o de borbulhia de placa. A avaliação da sobrevivência da enxertia foi realizada 180 dias após a sua realização, sendo contadas as plantas pegas de cada material genético. Para avaliar a diferença de pegamento dos enxertos entre os Estados, os dados de proporção foram submetidos à análise de variância e as médias agrupadas pelo teste de Scott-Knott. A sobrevivência dos enxertos provenientes das borbulhas dos estados do Paraná, Minas Gerais e São Paulo, que apresentaram percentual de sucesso de 94,4%, 93,0% e 86,0%, respectivamente, diferiram das de Santa Catarina que apresentou 71,0%. Conclui-se que a procedência dos materiais genéticos pode interferir no sucesso da enxertia por borbulhia de placa da araucária

SEM-EDS analyses of small craters in stardust aluminium foils: implications for the Wild-2 dust distribution

Implications for the Wild-2 dust distribution of the statistical results obtained by SEM-EDS from nearly 300 impact craters on aluminium foils of the Stardust sample tray assembly

Influence of grain size and mineralogy on the porosity/cement ratio

The porosity/cement ratio is defined as the ratio between porosity and the volumetric cement content (volume of cement over the total volume) and it is often adjusted by an exponent (xi) to the volumetric cement content (n/C-iv(xi)), which seems to depend on the type of soil. This ratio is very useful to analyse artificially cemented soils and it depends on easily calculated moulding properties. Although there are already some results regarding the correlation of this ratio with the mechanical behaviour of different soils, a theory explaining the variation of the exponent xi has yet to be established. In this work, the influence of grain size and mineralogy on xi was pursued, considering them to be the most important factors. For that purpose, a soil was divided into three different fractions, whose grain size distribution and mineralogy were known, and the exponents obtained correlating the ratio with the maximum shear modulus or the unconfined compression strength were compared. The results show that the grain size distribution explains part of the xi variation, but mineralogy and particle shape seem to have the most decisive influence. This was even more evident when comparing two uniform sands

Coordinated Analyses of Presolar Grains in the Allan Hills 77307 and Queen Elizabeth Range 99177 Meteorites

We report the identification of presolar silicates (~177 ppm), presolar oxides (~11 ppm), and one presolar SiO2 grain in the Allan Hills (ALHA) 77307 chondrite. Three grains having Si isotopic compositions similar to SiC X and Z grains were also identified, though the mineral phases are unconfirmed. Similar abundances of presolar silicates (~152 ppm) and oxides (~8 ppm) were also uncovered in the primitive CR chondrite Queen Elizabeth Range (QUE) 99177, along with 13 presolar SiC grains and one presolar silicon nitride. The O isotopic compositions of the presolar silicates and oxides indicate that most of the grains condensed in low-mass red giant and asymptotic giant branch stars. Interestingly, unlike presolar oxides, few presolar silicate grains have isotopic compositions pointing to low-metallicity, low-mass stars (Group 3). The 18O-rich (Group 4) silicates, along with the few Group 3 silicates that were identified, likely have origins in supernova outflows. This is supported by their O and Si isotopic compositions. Elemental compositions for 74 presolar silicate grains were determined by scanning Auger spectroscopy. Most of the grains have non-stoichiometric elemental compositions inconsistent with pyroxene or olivine, the phases commonly used to fit astronomical spectra, and have comparable Mg and Fe contents. Non-equilibrium condensation and/or secondary alteration could produce the high Fe contents. Transmission electron microscopic analysis of three silicate grains also reveals non-stoichiometric compositions, attributable to non-equilibrium or multistep condensation, and very fine scale elemental heterogeneity, possibly due to subsequent annealing. The mineralogies of presolar silicates identified in meteorites thus far seem to differ from those in interplanetary dust particles.Comment: 23 pages, 16 figure

Microcraters in aluminum foils exposed by Stardust

We will present preliminary results on the nature and size frequency distribution of microcraters that formed in aluminum foils during the flyby of comet Wild 2 by the Stardust spacecraft

Multiple generations of grain aggregation in different environments preceded solar system body formation

Manuscript submitted to Proceedings of the National Academy of ScienceThe solar system formed from interstellar dust and gas in a molecular cloud. Astronomical observations show that typical interstellar dust consists of amorphous (a-) silicate and organic carbon. Bona fide physical samples for laboratory studies would yield unprecedented insight about solar system formation, but they were largely destroyed. The most likely repositories of surviving presolar dust are the least altered extraterrestrial materials, interplanetary dust particles (IDPs) with probable cometary origins. Cometary IDPs contain abundant submicron a-silicate grains called GEMS, believed to be carbon-free. Some have detectable isotopically anomalous a-silicate components from other stars, proving they are preserved dust inherited from the interstellar medium. However, it is debated whether the majority of GEMS predate the solar system or formed in the solar nebula by condensation of high-temperature (>1300K) gas. Here, we map IDP compositions with single nanometer-scale resolution and find that GEMS contain organic carbon. Mapping reveals two generations of grain aggregation, the key process in growth from dust grains to planetesimals, mediated by carbon. GEMS grains, some with a-silicate subgrains mantled by organic carbon, comprise the earliest generation of aggregates. These aggregates (and other grains) are encapsulated in lower density organic carbon matrix, indicating a second generation of aggregation. Since this organic carbon thermally decomposes above ~450K, GEMS cannot have accreted in the hot solar nebula and formed, instead, in the cold presolar molecular cloud and/or outer protoplanetary disk. We suggest that GEMS are consistent with surviving interstellar dust, condensed in situ, and cycled through multiple molecular clouds.Portions of this work were performed at the Molecular Foundry and the Advanced Light Source at Lawrence Berkeley National Laboratory, which are supported by the Office of Science, Basic Energy Sciences, U.S. Department of Energy under Contract No. DE-AC02-05CH11231. HAI acknowledges funding by NASA’s Laboratory Analysis of Returned Samples and Emerging Worlds Programs (NNX14AH86G and NNX16AK41G). JPB acknowledges funding by NASA’s Cosmochemistry Program (NNX14AI39G). CF acknowledges funding by NASA’s Cosmochemistry Program (NNX14AG25G)

IMPACTO AMBIENTAL NA IMPLANTAÇÃO DE AEROPORTOS

Os aeroportos são, caracterizados por serem estruturas com grande impacto modificador do meio ambiente. O presente trabalho apresenta os principais impactos que a implantação de aeroportos, bem como ações mitigadoras, que visam reduzir ou amenizar as conseqüências desses impactos. A questão ambiental passou a ser um fator de extrema importância na tomada de decisões para a sua autorização. Desta forma, ações mitigadoras tem auxiliado à combater os impactos negativos tanto de caráter local, como global, bastando aplicar as leis e normatizações vigentes no Brasil

MTO1 mediates tissue specificity of OXPHOS defects via tRNA modification and translation optimization, which can be bypassed by dietary intervention

Mitochondrial diseases often exhibit tissue-specific pathologies, but this phenomenon is poorly understood. Here we present regulation of mitochondrial translation by the Mitochondrial Translation Optimization Factor 1, MTO1, as a novel player in this scenario. We demonstrate that MTO1 mediates tRNA modification and controls mitochondrial translation rate in a highly tissue-specific manner associated with tissue-specific OXPHOS defects. Activation of mitochondrial proteases, aberrant translation products, as well as defects in OXPHOS complex assembly observed in MTO1 deficient mice further imply that MTO1 impacts translation fidelity. In our mouse model, MTO1-related OXPHOS deficiency can be bypassed by feeding a ketogenic diet. This therapeutic intervention is independent of the MTO1-mediated tRNA modification and involves balancing of mitochondrial and cellular secondary stress responses. Our results thereby establish mammalian MTO1 as a novel factor in the tissue-specific regulation of OXPHOS and fine tuning of mitochondrial translation accurac