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Search Results: 1 - 10 of 9523 matches for " PATRICIA; FOCARDI "
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Polybrominated Diphenyl Ethers and Polychlorobiphenyls in Fish from the Ionian Sea (Western Mediterranean)  [PDF]
Silvano Focardi, Monia Renzi
Journal of Environmental Protection (JEP) , 2012, DOI: 10.4236/jep.2012.32017
Abstract: This study reports on the accumulation of polybrominated diphenyl ethers (PBDEs) and polychlorobiphenyls (PCBs) in the muscle tissue of 11 species of fish from the Ionian Sea (Western Mediterranean). The results are consistent with previous studies that have reported now-generalized contamination by PCBs of the Mediterranean marine environment, as well as widespread diffusion of emerging contaminants such as polybrominated diphenyl ethers (PBDEs). The Western Mediterranean Sea, from which the 11 fish species were collected, receives a heavy pollutant input from the urban and industrial areas along its coasts. Higher values of PCBs (average over 1.5 mg/kg f.w.) were observed in pelagic top predators (little tuna, bluefin tuna and swordfish). These same species also showed higher levels of PBDEs, averaging above 0.5 ng/g f.w. This puts a few fish species at the top of the food chain—such as bluefin tuna and swordfish—at particular risk, and the importance of these species in the human diet suggests the need for particular care in our food choices.
PLAGUICIDAS ORGANOCLORADOS PERSISTENTES EN SEDIMENTOS DE TRES LAGOS COSTEROS Y UN LAGO ANDINO DE CHILE CENTRAL
BARRAL,RICARDO; POZO,KARLA; ROBERTO,URRUTIA; CISTERNAS,MARCO; PACHECO,PATRICIA; FOCARDI,S.;
Boletín de la Sociedad Chilena de Química , 2001, DOI: 10.4067/S0366-16442001000200008
Abstract: we have measured concentrations and distribution of persistent organic compounds (poc) in sediment cores from four chilean lakes: laguna chica de san pedro, laguna grande de san pedro, lleu-lleu, and icalma. the organochlorine compounds were extracted with n-hexane in a soxhlet system and then identified and quantified by gas chromatography using a 63 ni electron capture detector. statistical analyses were performed using a principal components analysis (pca) and the pearson correlation. the following pesticides were identified in the sediments: a-hch, lindane, heptachlor, aldrin, pp'-ddt, pp'-dde, and pp'-ddd. the results show variation in both poc distribution and concentration when comparing pristine and urban lakes. it is important to note that pp'-dde (range:b.d.l.-1.68 ng g-1 d.w.) and pp'-ddt (range: b.d.l.-0.89 ng g-1 d.w.) were present in three of the four lakes in the study. the statistical analyses showed significant correlations between pp'-dde and pp'-ddd. correlations between pp'-ddt and its metabolites were not detected. the pca showed groupings of some of the organic compounds based on concentration and degradation over time. it is concluded that laguna chica de san pedro is the lake with the highest concentration of poc's, although the levels appear low when compared with those measured in pristine areas in southern chile
Homogenization of random fractional obstacle problems via $Γ$-convergence
M. Focardi
Mathematics , 2009,
Abstract: $\Gamma$-convergence methods are used to prove homogenization results for fractional obstacle problems in periodically perforated domains. The obstacles have random sizes and shapes and their capacity scales according to a stationary ergodic process. We use a trace-like representation of fractional Sobolev norms in terms of weighted Sobolev energies established by Caffarelli and Silvestre, a weighted ergodic theorem and a joining lemma in varying domains following the approach by Ansini and Braides. Our proof is alternative to those contained in the papers by Caffarelli and Mellet.
Aperiodic fractional obstacle problems
Matteo Focardi
Mathematics , 2009,
Abstract: We determine the asymptotic behaviour of (bilateral) obstacle problems for fractional energies in rather general aperiodic settings via Gamma-convergence arguments. As further developments we consider obstacles with random sizes and shapes located on points of standard lattices, and the case of random homothetics obstacles centered on random Delone sets of points. Obstacle problems for non-local energies occur in several physical phenomenona, for which our results provide a description of the first order asympotitc behaviour.
Water Pollution by Surfactants: Fluctuations Due to Tourism Exploitation in a Lagoon Ecosystem  [PDF]
Monia Renzi, Andrea Giovani, Silvano E. Focardi
Journal of Environmental Protection (JEP) , 2012, DOI: 10.4236/jep.2012.39116
Abstract: This paper describes recent levels of surfactants measured in a coastal lagoon ecosystem highly stressed by human activites: the Orbetello lagoon (Southern Tuscany, Italy, Ramsar Site IT008). Significance of difference among concentrations measured before and after summertime are explored in order to evaluate effects related to tourism exploitation. Among surfactants, methylene blue active anionic substances (MBAS) are selected as tracers for untreated discharges originated by domestic and urban activities. Water samplings were performed in 2011 following a randomly replicated nested logic model (n = 144). MBAS mean level of 0.070 mg.L–1 (<0.001 - 0.259 mg.L–1) and 0.530 mg.L–1 (–1) are respectively recorded in June and October evidencing a significant increase after the touristic season. Possible MBAS concentration phenomena could be induced by different evaportaton rates among sampling stations and between winter and summer seasons and were evaluated, in this study, using water salinity as possible factor affecting samples segregations. Results evidence that differences of MBAS levels related to evaporation rates are trascurabile if compared to the variability induced by the presence of not-collected wastewater hot-spot pollution sources located closed around the urban settlement and along sandbars. Measured levels of surfactants could act negatively on living organisms both animals and plants contributing to affect Orbetello lagoon biodiversity. In this ecosystem, after the complete reorganization of urban wastewater treatment plants occured in 2008, further management actions should be focalized on reducing untreated sources of MBAS.
Biofuel Production from the Orbetello Lagoon Macrophytes: Efficiency of Lipid Extraction Using Accelerate Solvent Extraction Technique  [PDF]
Monia Renzi, Andrea Giovani, Silvano E. Focardi
Journal of Environmental Protection (JEP) , 2013, DOI: 10.4236/jep.2013.411140
Abstract:

In this paper, the efficiency of lipid extraction from macrophytes (Chaetomorpha linum, Ulva laetevirens, Valonia aegagrophyla, Gracilariopsis longissima, Ruppia cirrhosa) for the biodiesel production is evaluated using four different methods based on the Accelerated Solvent Extraction technique. Both wet and dried tissues are extracted and effects induced on lipid recovery by the pressure and the solvent mixture selection are evaluated. Results evidenced that better extraction performance is obtained using a polar/hydrophobic solvent mixture (1:1 v/v). Accelerate Solvent Extraction technique significantly improves the total amount of lipid extracted from macrophytes tissues even if average values are about 2% of the dry weight. Observed efficiencies are far from the productive standards required by the industrial process; nevertheless, lipid extraction from macrophytes could represent an interesting step of a much more complex biomass recycling process which could include, besides biodiesel, also, the production of other commercial materials as well as pigments and biosorbents.

Responses of Aquatic Vegetation to Pollution: Preliminary Results on Ecotoxicological Effects and Bioenrichment Factors  [PDF]
Monia Renzi, Andrea Giovani, Silvano E. Focardi
Journal of Environmental Protection (JEP) , 2014, DOI: 10.4236/jep.2014.54031
Abstract:

This study evaluates, on a preliminary basis, the principal morpho-physiological effects induced by pollution stress in four aquatic vegetation species of great ecological relevance in transitional water ecosystems. Three macroalgae (Chaetomorpha linum, Valonia aegagrophyla, Graciliariopsis longissima) and one phanerogams species (Ruppia cirrhosa) were exposed to different doses of trace elements (Cu, Hg, Zn) and surfactants (dodecylbenzenesulfonic acid sodium salt) in laboratory controlled microcosm conditions and morpho-physiological responses (photosynthetic complex alteration, percentage of died cells, morphological changes) were measured before and after 7 and 14 days of exposure. Levels of pollutants in tissues and BioConcentration Factors (BCF) for each species were calculated after 14 days of exposure. Results suggest that photosynthetic complex alteration can be a useful tool to evaluate early and sub-lethal significant changes due to exposure to pollution stress in all of the considered species. A clear species-specificity was observed concerning trace element levels in tissues after 14 days of exposure, while dose-dependent behavior was observed for BCFs.

Compact groups in the UZC galaxy sample
Paola Focardi,Birgit Kelm
Physics , 2002, DOI: 10.1051/0004-6361:20020377
Abstract: Applying an automatic neighbour search algorithm to the 3D UZC galaxy catalogue (Falco 1999) we have identified 291 compact groups (CGs) with redshifts between 1000 and 10000 km/s. The sample is analysed to investigate whether Triplets display kinematical and morphological characteristics similar to higher order CGs (Multiplets). It is found that Triplets constitute low velocity dispersion structures, have a gas-rich galaxy population and are typically retrieved in sparse environments. Conversely Multiplets show higher velocity dispersion, include few gas-rich members and are generally embedded structures. Evidence hence emerges indicating that Triplets and Multiplets, though sharing a common scale, correspond to different galaxy systems. Triplets are typically field structures whilst Multiplets are mainly subclumps (either temporarily projected or collapsing) within larger structures. Simulations show that selection effects can only partially account for differences, but significant contamination of Triplets by field galaxy interlopers could eventually induce the observed dependences on multiplicity.
The effect of the environment on the Faber Jackson relation
Paola Focardi,Nicola Malavasi
Physics , 2012, DOI: 10.1088/0004-637X/756/2/117
Abstract: We investigate the effect of the environment on the Faber Jackson (FJ) relation, using a sample of 384 nearby elliptical galaxies and estimating objectively their environment on the typical scale of galaxy clusters. We show that the intrinsic scatter of the FJ is significantly reduced when ellipticals in high density environments are compared to ellipticals in low density ones. This result, which holds on a limited range of overdensities, is likely to provide an important observational link between scaling relations and formation mechanisms in galaxies.
Compact Groups in the UZC galaxy sample: II. Connections between morphology, luminosity and large-scale density
Kelm Birgit,Focardi Paola
Physics , 2003,
Abstract: The nature of Compact Groups (CGs) is investigated by comparing the luminosities and morphologies of CG galaxies, CG Neighbours and Isolated galaxies. CGs turn out to include more early type galaxies than Isolated galaxies and fewer low-luminosity galaxies. The 33 CGs with a dominant E/S0 and the 30 CGs with a dominant spiral have similar LF parameters. Spiral dominated CGs have fewer galaxies at high and low luminosity in comparison with their Neighbours, while E-S0 dominated CGs seem to lack only faint galaxies when compared to their Neighbours. Ellipticals which are the dominant galaxy of a CG are also brighter than all their Neighbours, while this holds true for only half of the dominant spirals and S0s. Relations linking the number of Neighbours of dominant E-S0s to the luminosity of E-S0s and to the difference between the first and the second ranked CG members do suggest a link between the formation of bright early-type galaxies and the presence of a group-like potential. No similar relations are found for dominant spirals. These tentative results are compatible with the assumption that CG dominant Ellipticals are anomalous galaxies whose formation might have been a secondary outcome during the process of groups formation.
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