6,340 research outputs found
Environmental assessment of humic acid coated magnetic materials used as catalyst in photo-fenton processes
Persistent organic pollutants have been increasingly detected in natural waters, and this represents a real challenge to the quality of this resource. To remove these species, advanced treatment technologies are required. Among these technologies, Fenton-like and photo-Fenton-like processes have been investigated for the removal of pollutants from water. Delicate aspects of photo-Fenton processes are that light-driven processes are energy intensive and require a fair amount of chemical inputs, which strongly affects their overall environmental burdens. At present, aside from determining the efficiency of the processes to remove pollutants of a particular technology, it becomes fundamental to assess also the environmental sustainability of the overall process. In this work, the methodology of the life cycle assessment (LCA) was applied to identify the hotspots of using magnetite particles covered with humic acid (Fe3O4/HA) as a heterogeneous photo-Fenton catalyst for water remediation. The sustainability of the overall process was considered, and a comparative LCA study was performed between H2O2 and persulfate activation at different pH. The addition of humic substances to the particles allows the effectiveness of the catalyst to improve without increasing the environmental impacts; these processes are strongly correlated with energy consumption and therefore with the efficiency of the process. For this reason, working at acidic pH allows us to contain the impacts
Avaliação da qualidade e conservação pós-colheita de frutos de tomate orgânico produzidos com diferentes sistemas de irrigação.
Avaliou-se a influência de diferentes sistemas de irrigação na qualidade e conservação pós-colheita de frutos de tomate produzidos de forma orgânica. O estudo foi conduzido na Embrapa Hortaliças, Distrito Federal, durante período seco do ano (maio-outubro).Trabalho 10718. Trabalho apresentado no 7. Congresso Brasileiro de Agroecologia, Fortaleza, 2011
Correlating Pedestrian Flows and Search Engine Queries
An important challenge for ubiquitous computing is the development of
techniques that can characterize a location vis-a-vis the richness and
diversity of urban settings. In this paper we report our work on correlating
urban pedestrian flows with Google search queries. Using longitudinal data we
show pedestrian flows at particular locations can be correlated with the
frequency of Google search terms that are semantically relevant to those
locations. Our approach can identify relevant content, media, and
advertisements for particular locations.Comment: 4 pages, 1 figure, 1 tabl
Folding model analysis of alpha radioactivity
Radioactive decay of nuclei via emission of particles has been
studied theoretically in the framework of a superasymmetric fission model using
the double folding (DF) procedure for obtaining the -nucleus
interaction potential. The DF nuclear potential has been obtained by folding in
the density distribution functions of the nucleus and the daughter
nucleus with a realistic effective interaction. The M3Y effective interaction
has been used for calculating the nuclear interaction potential which has been
supplemented by a zero-range pseudo-potential for exchange along with the
density dependence. The nuclear microscopic -nucleus potential thus
obtained has been used along with the Coulomb interaction potential to
calculate the action integral within the WKB approximation. This subsequently
yields microscopic calculations for the half lives of decays of
nuclei. The density dependence and the exchange effects have not been found to
be very significant. These calculations provide reasonable estimates for the
lifetimes of radioactivity of nuclei.Comment: 7 pages including 1 figur
Consumo voluntário e digestibilidade aparente da matéria seca, matéria orgânica, energia e parede celular das silagens de quatro genótipos de girassol (Helianthus annus).
O valor nutricional de silagens de quatro genótipos de girassol (Rumbosol 91, M734, C11 e S430) foi avaliado a partir do consumo voluntário e da digestibilidade aparente da matéria seca, da matéria orgânica, da energia e dos componentes da parede celular. Vinte carneiros adultos foram alojados em gaiolas metabólicas, em delineamento inteiramente ao acaso, com quatro tratamentos e cinco repetições. Não foram observadas diferenças para consumo de matéria seca, matéria orgânica, energia digestível e metabolizável e dos componentes fibrosos entre os genótipos de girassol. A digestibilidade aparente da matéria orgânica foi superior para os genótipos R91, M734 e S430, no entanto não influenciou o consumo de matéria orgânica digestível. As silagens de girassol foram classificadas como alimento volumoso de boa qualidade, uma vez que o consumo de matéria seca foi acima dos requisitos recomendados para mantença animal, 63,6; 69,6; 50,2 e 74,5g MS/kg0,75/dia para R91, M734, C11 e S430, respectivamente. O baixo coeficiente de digestibilidade aparente médio da FDN (32,3%) e da FDA (28,7%) foi conseqüência da baixa qualidade dos constituintes da parede celular das silagens de girassol utilizadas
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