1,721,326 research outputs found
Modified clays for environmental remediation: Wastewater treatment
No full textA comprehensive analysis of more than 7,000 topsoil and subsoil samples in Australia, matched with remote sensing and other data, confirms that clays are abundant, pervasive and regionally distributed across this significantly weathered continental landscape1. The predominant use of these clays within Australia is for building materials (e.g. paints, paper filler, bricks), ceramics and porcelain, horticulture and environmental remediation. Commercial use of clays in environmental remediation is as liners, geological barriers and containment walls in tailings dams, landfills, wetlands and water supply channels. Geosynthetic clay liners have widespread use in the construction/civil, mining and environmental sectors in Australia and involve forming bentonite within a flexible engineered fabric but the clay is essentially unmodified. This talk will focus on chemical modifications of clays resulting in either transformation of the source aluminosilicate or enhanced functionality due to adsorption of key compounds/elements
A green and efficient technology to recover rare earth elements from weathering crusts
No full textHeavy rare earth elements (HREEs) such as Gd-Lu, Sc and Y are irreplaceable metals for a number of critical (including clean) technologies, but they are scarce. Ion-adsorption deposits, which form within weathering crusts, supply more than 95% of the global HREE demand. However, these deposits are currently mined via ammonium-salt-based leaching techniques that are responsible for severe environmental damage and show low recovery efficiency. As a result, the adoption of such techniques is restricted for REE mining, further exacerbating REE scarcity, which in turn could lead to supply chain disruptions. Here we report the design of an innovative REE mining technique, electrokinetic mining (EKM), which enables green, efficient and selective recovery of REEs from weathering crusts. Its feasibility is demonstrated via bench-scale, scaled-up and on-site field experiments. Compared with conventional techniques, EKM achieves similar to 2.6 times higher recovery efficiency, an similar to 80% decrease in leaching agent usage and a similar to 70% reduction in metallic impurities in the obtained REEs. As an additional benefit, the results point to an autonomous purification mechanism for REE enrichment, wherein the separation process is based on the mobility and reactivity diversity between REEs and metallic impurities. Overall, the evidence presented suggests that EKM is a viable mining technique, revealing new paths for the sustainable harvesting of natural resources
Infrared study of HDTMA+ intercalated montmorillonite
No full textIn this paper, FTIR spectroscopy using ATR and KBr pressed disk techniques has been used to characterize sorbed water and HDTMA+ in organo-clay. Sorbed water content decreases with the intercalation of HDTMA+. With the decrease of the sorbed water content, the position of the ν2 mode shifts to higher frequency dramatically while the stretching vibration shifts to lower frequency slightly, indicating that H2O is less hydrogen bonded. This might be resulted from the polarization of H2O molecules by the changeable cations and HDTMA+. FTIR spectra show that both antisymmetric and symmetric CH2 stretching absorption bands shift to low frequencies with increase of amine concentration within the galleries of montmorillonite, elucidating the increase of ordered conformation. Furthermore, the present study demonstrates that the antisymmetric CH2 stretching mode is more sensitive to the conformational ordering than the symmetric stretching mode does. When KBr pressed disk technique used, two well resolved absorption bands at 730 cm-1 and 720 cm-1, and at 1473 cm-1 and 1463 cm-1, corresponding to the methylene scissoring and rocking modes, respectively, could be observed in FTIR spectra of organo-clays with relative higher concentration of surfactant. However, the FTIR spectra using ATR technique only display singlets and they are independent of amine concentration and chain conformation. Our present study demonstrates that FTIR spectroscopy using KBr pressed disk technique is more suitable to probe the conformational ordering of surfactant in organo-clays than that suing ATR technique does
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
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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