1,721,074 research outputs found
Adult Chronic Exposure to Neurotoxic Metals Associated with Atmospheric Aerosols: A Case Study in The Urban Area of Turin (NW Italy)
No full textParticulate Matter (PM) pollution still represents a great concern for its adverse effects on human health. Among the emerging risks, the neuro-toxicity of PM-associated metals has been evidenced by the scientific literature. Since PM inhalation plays an important role with respect to its toxicity, there is a recognized need for improving the studies with respect to its deposition sites. This work is focused on the assessment of PM10-associated metals in the urban environment of Turin (NW Italy), one of the most polluted European areas. Data of PM10-associated metals mass size distribution, percentage repartition associated to the respiratory appa-ratus, relative concentration peaks, together with preferential deposition sites and the daily inhaled dose have been calculated. The analyzed metals were: As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sn, V and Zn. The data are limited, considering a precautionary approach, to the winter season, when the intensity and number of sources is greater and only in the case of stable good weather conditions, when the atmospheric removal pro-cesses have a more limited impact on the aerosol dynamics. The results show that the element concentrations in Torino atmospheric PM are similar to those of other considered European towns. The measures evidence a preferential association of each metal with different areas of the respiratory apparatus Furthermore, ordering the analyzed metals with respect to the daily inhaled dose, from higher to lower, we have: Fe, Zn, Sn, Cd, Mn, Cu, Pb, Ni, Cr, Mo, V, As and Co. Even if the risk doesn’t seem to be significant up to now (apart from Cr), the evolving knowledge on the effects of chronic sub-threshold exposure might give a different evidence in the future. PM10 size repartition measurement, together with the analysis of PM10-associated compounds, could well intermittently complement the routine air quality measures with the purpose of increasing the present body of knowledge with respect to PM neurotoxicity, allowing to improve both the existing risk assessment procedures and the public health management
Investigation of the mobility of the glycosidic linkage in sucrose through the study of the phase space structure of a two-degrees of freedom model
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Adsorption of heavy metals on Na-montmorillonite. Effect of pH and organic substances
No full textClays (especially montmorillonite and bentonite) are widely used as barriers in landfills to prevent contamination of subsoil and groundwater by leachates containing heavy metals. For this reason it is important to study the adsorption of metals by these clays. The sorption of seven metals (Cd, Cr, Cu, Mn, Ni, Pb and Zn) on Na-montmorillonite was studied as a function of pH and in the presence of ligands, forming complexes of different stabilities with the metals of interest. The continuous column method was used as it better simulates natural conditions. The total capacity of Na-montmorillonite towards these metals was determined. The pH variations influence to a higher extent the concentrations of Cu, Pb and Cd in the effluent. Moreover the results suggest that complex formation hinders the sorption of the metals on the clay, with an increasing influence in the order: Mn less than or equal to Pb less than or equal to Cd less than or equal to Zn < Ni < Cu < Cr. The evaluation of the total capacity of Na-montmorillonite shows that this clay is a good sorbent towards all examined metals
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Gold nanostructured electrode for the electrochemical determination of mercury in canned tuna
Full text linkThe presence of mercury even at trace and ultratrace level in food constitutes a risk for human health. Therefore, it is important to develop reliable and sensitive analytical methods for the determination of this metal to study how it affects the food chain. Since fish accumulates substantial amounts of mercury in its tissues and constitutes the first source of this element in humans diet, a widespread monitoring of mercury levels in seafood is needed. The applicability of the square wave anodic stripping voltammetry (SW-ASV) for mercury quantification was evaluated adopting a solid gold electrode (SGE) and a nanoparticle-modified glassy carbon electrode (AuNPs-GCE) in certified reference materials and in samples of canned tuna. The achieved results were compared with those obtained by conventional cold vapour atomic absorption spectroscopy (CV-AAS) and by a direct mercury analyser (DMA) based on AAS detection. The evaluation pointed out that SW-ASV is well suited for mercury detection, since a good agreement between spectroscopic and electrochemical approaches was observed. Therefore, SW-ASV can be used with both mentioned electrodes to monitor the mercury content in tuna fish, since the maximum admissible level has been set by European Legislation to 1 mg/kgfw. Furthermore, the SW-ASV coupled with AuNPs-GCE displayed a higher sensitivity than that recorded with SGE: accurate mercury determinations at concentrations lower than 0.1 mg/kg fresh weight (fw) were obtained, showing a limit of quantification comparable to that of DMA. Further advantages of the SW-ASV regard the instrumentation cost that is lower than that required for DMA or CV-AAS, and the presence of this instrumentation in the most of analytical laboratories. Thus, SW-ASV coupled with AuNPs-GCE can be considered suitable for mercury determination even at ultratrace level in tuna fish, and can be adopted as an alternative method by the designated laboratories for routine analysis
Adsorption of heavy metals on vermiculite. Influence of pH and organic ligands
No full textThe sorption behaviour of vermiculite has been studied with respect to cadmium, copper, lead, manganese, nickel, and zinc as a function of pH and in the presence of different ligands. The continuous column method was used in order to evaluate the feasibility to use the clay in wastewater purification systems. The total capacity of vermiculite was found to decrease in the following order: Mn > Ni > Zn > Cd > Cu > Pb. The adsorption of metal ions on vermiculite decreases with decreasing pH and increasing ionic strength. In general, the metal uptake on the clay was hindered by the presence of strong complexing agents in solution and it decreases with increasing of the complexation constants of the ligands with exception of cysteine and tiron. It is necessary, hence, to consider all these factors to effectively predict the uptake efficiency of this sorbent. However, it is possible to conclude that the vermiculite has good potentialities for cost-effective treatments of metal-contaminated wastewaters
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