587 research outputs found
Variations In Desiccation Tolerance In Seeds Of Eugenia Pyriformis: Dispersal At Different Stages Of Maturation
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Eugenia pyriformis Cambess., known locally as uvaieira, a species of fruit-bearing tree with both pharmacological and gastronomic potential, has seeds which are sensitive to desiccation. The aim of this study was to analyse whether the degree of tolerance to desiccation of uvaieira seeds depends on the stage of maturation of the seeds at shedding. This, in turn, depends on the environmental conditions in which the seeds develop, including the accumulation of degree-days and rainfall in the period. Seeds were collected from the ripe fruit of parent plants located in the states of São Paulo and Minas Gerais, Brazil, submitted to drying and analysed for water content and germination. A completely randomised design was used in a 20 × 3 factorial scheme (source of material x level of drying). The degree of desiccation tolerance differs between region and period of collection, even for the same parent plant when the seeds are collected in different years. The water and thermal conditions of the environment during seed development modify the maturation cycle, the physiological quality and the acquisition of desiccation tolerance. In uvaieira seeds, desiccation tolerance depends on the physiological maturity of the seeds at the time of dispersal, which is associated with the environmental conditions.471118126CAPES, Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES
Alcalóides de Duguetia trunciflora Maas (Annonaceae)
From the ethanolic extract of the leaves and thin branches of Duguetia trunciflora Maas (Annonaceae) six alkaloids were isolated, being one benzylisoquinoline: reticuline¹, four tetrahydroprotoberberine:,tetrahydro-palmatine², tetrahydrojathrorrizine³, discretamine4, thaicanine5, and one berberine: jathrorrizine6. These alkaloids were identified through ¹H and 13C NMR spectroscopic technics. The alkaloids 1, 3, 5 and 6 are being cited for the first time on Duguetia genus
Treatment of ex-situ soil-washing fluids polluted with petroleum by anodic oxidation, photolysis, sonolysis and combined approaches
In this research, the treatment of soil spiked with petroleum was studied using a surfactant-aided soil-washing (SASW) process followed by sonolysis (US), photolysis and boron doped diamond electrolysis (BDD-electrolysis) for washing liquid treatment. Results clearly demonstrate that SASW is a very efficient approach in the treatment of soil, removing completely the petrochemical compounds by using dosages about 5 g of extracting surfactant (sodium dodecyl sulfate (SDS)) per kg of soil. The main characteristics of the effluents produced in this soil remediation technology as well as the efficiency of the treatment (US, photolysis and BDD-electrolysis) depend on the dosage of SDS. Depollution of the effluents (degradation and mineralization of the organic matter) is related to the reduction in size of micelles formed by SDS and petroleum, and it depends on the treatment used. US and photolysis were inefficient decontamination processes, while BDD-electrolysis favors the complete depletion of micelles. However, the intensification of the efficiency was attained by synergic degradation effects when UV light irradiation and US were coupled with BDD-electrolysis, US/BDD-electrolysis and photo/BDD-electrolysis, respectively. Sulfate (coming from SDS) ions play an important role during the BDD-electrolysis, US/BDD-electrolysis and photo/BDD-electrolysis because persulfate and persulfate radicals are produced (by sulfate activation applying US or photolysis), improving the efficiency of the processes
Measurement of single electron emission in two-phase xenon
We present the first measurements of the electroluminescence response to the
emission of single electrons in a two-phase noble gas detector. Single
ionization electrons generated in liquid xenon are detected in a thin gas layer
during the 31-day background run of the ZEPLIN-II experiment, a two-phase xenon
detector for WIMP dark matter searches. Both the pressure dependence and
magnitude of the single-electron response are in agreement with previous
measurements of electroluminescence yield in xenon. We discuss different
photoionization processes as possible cause for the sample of single electrons
studied in this work. This observation may have implications for the design and
operation of future large-scale two-phase systems.Comment: 11 pages, 6 figure
The ZEPLIN II dark matter detector: data acquisition system and data reduction
ZEPLIN-II is a two-phase (liquid/gas) xenon dark matter detector searching
for WIMP-nucleon interactions. In this paper we describe the data acquisition
system used to record the data from ZEPLIN-II and the reduction procedures
which parameterise the data for subsequent analysis.Comment: 11 pages, 10 figure
The ZEPLIN II dark matter detector: data acquisition system and data reduction
ZEPLIN-II is a two-phase (liquid/gas) xenon dark matter detector searching
for WIMP-nucleon interactions. In this paper we describe the data acquisition
system used to record the data from ZEPLIN-II and the reduction procedures
which parameterise the data for subsequent analysis.Comment: 11 pages, 10 figure
Limits on spin-dependent WIMP-nucleon cross-sections from the first ZEPLIN-II data
The first underground data run of the ZEPLIN-II experiment has set a limit on
the nuclear recoil rate in the two-phase xenon detector for direct dark matter
searches. In this paper the results from this run are converted into the limits
on spin-dependent WIMP-proton and WIMP-neutron cross-sections. The minimum of
the curve for WIMP-neutron cross-section corresponds to 0.07 pb at a WIMP mass
of around 65 GeV.Comment: 12 pages, 2 figures, to be published in Physics Letters
Impactos ambientais do manejo agroecológico da caatinga no Rio Grande do Norte.
O objetivo deste trabalho foi avaliar os impactos ambientais do manejo agroecológico da caatinga, em unidades de produção familiar no Rio Grande do Norte, pelo método Ambitec de produção animal - dimensão ambiental, desenvolvido pela Embrapa Meio Ambiente. Foram avaliadas sete unidades de produção familiar, em quatro projetos de assentamentos de reforma agrária do Município de Apodi, RN. Os dados para o levantamento foram obtidos por meio de questionários aplicados aos representantes das unidades produtivas familiares, que atribuíram, a cada variável estudada, um valor que representou a alteração proporcionada pela implementação da tecnologia. Após a inserção dos coeficientes de alteração de cada variável dos indicadores por unidade de produção, o coeficiente de impacto foi automaticamente calculado por meio da planilha Ambitec. O manejo agroecológico da caatinga resultou num impacto ambiental positivo, e suas maiores contribuições foram relacionadas aos efeitos positivos dos seguintes indicadores: capacidade produtiva do solo, uso de insumos materiais, qualidade do produto e diminuição da emissão de poluentes à atmosfera. Dois indicadores geraram efeitos negativos: o uso de energia e o uso de recursos naturais. Pela superioridade dos benefícios gerados, o manejo agroecológico da caatinga é uma inovação tecnológica geradora de impactos ambientais positivos
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