1,720,958 research outputs found
Cerium oxide nanoparticles influence the life cycle of spontaneous plant species
No full textThe tumultuous development of nanotechnology, a new emerging field of science, and the consequent increasing use of engineered nanomaterials (ENMs) in different products and applications are considered a potential threat not only for human health but also for the environment. Studies regarding the impacts of such materials on living organisms and biota and their potential transfer through the food web are analyzed in very few studies and are still at an early stage. Released ENMs could accumulate into environmental compartments where they could establish complex interactions with different abiotic and biotic components, especially in terrestrial ecosystems. Different studies, regarding ENMs, focus the attention on crops, but the effects of these new materials on common and spontaneous species are quite completely unknown and poorly investigated. This aspect could be important in view of a future possible Ecological Risk Assessment. Cerium oxide nanoparticles (nCeO2) are one of the most widely utilized ENMs in Europe and have a great potential to accumulate and affect the environment because of their widespread applications in commercial products. The remarkable and rapid increase in the use of CeO2 nanoparticles in many application areas caused the spread of these materials even in the different environmental matrices. For example, when CeO2 reached the soil, it could be absorbed by vegetation, it could go down deeper into the soil layers, contaminating aquatic groundwater, or it could also enter into the food chain. A germination experiment and a pot soil study were carried out in order to observe the response of 3 spontaneous plant species (Holcus lanatus L., Diplotaxis tenuifolia L. DC. and S. flos cuculi L.) and to different concentrations of nCeO2 having different dimensions (25 nm and 50 nm, respectively). Germination and root elongation, plant growth parameters and nCeO2 uptake and bioaccumulation were investigated. In the 3 pecies, nCeO2 treatments increase the percentage of germination and stimulate root elongation in the first stages of plants. Moreover, they increase the development of roots if it is compared with control and the same comparison could be done for leaf area, with higher values in treated plants than in control ones. ICP – MS analysis highlight that, at the same high concentration of nCeO2, plants absorb more 25 nm particles than 50 nm, because nCeO2 50 nm tend to agglomerate and their uptake becomes more difficult
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
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
Single and Repeated Applications of Cerium Oxide Nanoparticles Differently Affect the Growth and Biomass Accumulation of Silene flos-cuculi L. (Caryophyllaceae)
Full text linkCerium oxide nanoparticles (nCeO2) have a wide variety of applications in industry. Models demonstrated that nCeO2 can reach environmental compartments. Studies regarding the relationships between plants and nCeO2 considered only crop species, whereas a relevant knowledge gap exists regarding wild plant species. Specimens of Silene flos-cuculi (Caryophyllaceae) were grown in
greenhouse conditions in a substrate amended with a single dose (D1) and two and three doses (D2 and D3) of 20 mg kg1 and 200 mg kg1 nCeO2 suspensions, respectively. sp-ICP-MS and ICP-MS data demonstrated that nCeO2 was taken up by plant roots and translocated towards aerial plant fractions. Biometric variables showed that plants responded negatively to the treatments with a shortage in biomass of roots and stems. Although not at relevant concentrations, Ce was accumulated mainly in roots and plant leaves
Gaseous Elemental Mercury Level and Distribution in a Heavily Contaminated Site: the Ex-chlor Alkali Plant in Torviscosa (Northern Italy)
No full textMercury (Hg) poses environmental and health risks due to its global distribution and high toxicity exhibited in some of its chemical forms. Although Hg is naturally present in the environment, human activities
have increased its cycling among the land, atmosphere and ocean by a factor of three to five comparing the pre-industrial period to the present day. The Torviscosa chlor-alkali plant (CAP), which operated
since the beginning of twentieth century, was one of the most important Cl2 production capacity in the Northern Italy and was responsible for an uncontrolled discharge of Hg in the surrounding area. Previous studies reported the high degree of Hg pollution in soils, river sediments and surface waters of the area, but the Hg level in the atmospheric media was never taken into consideration. In this work, an integrated approach was applied with the aim to assess the level, distribution and dispersion of gaseous elemental mercury (GEM) close to the CAP area. GEM levels were monitored by means of four surveys conducted from September 2014 to July 2015, at fixed locations and covering an area of about 10 km2 (including CAP area, Torviscosa village and reclaimed land), accomplished to Hg bioaccumulation measurements in selected lichens. The results indicate that the CAP area currently represents the main source of GEM in the Friuli Venezia Giulia region. The highest levels were found close to the old factory’s buildings (more than 5000 ng m−3), whereas other sites are less impacted. The emission of GEM is not clearly related to the intensity of solar radiation (temperature) at the soil level; however, this latter influences the release
from the old buildings employed in the past for the production activities. The most important factor driving the GEM dispersion is the wind, as confirmed by the map of lichens bioaccumulation. In this context, the
GEM plume partially affects the nearby village of Torviscosa (about 1 km), but the values found were always well below the international thresholds for residential areas, thus excluding the risk of inhalation for
local inhabitants
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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