1,721,107 research outputs found

    Photo-reduction and adsorption in aqueous Cr(VI) solution by titanium dioxide, carbon nanotubes and their composite

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    [[abstract]]BACKGROUND: This study compared the removal of aqueous Cr(VI) by multi-walled carbon nanotubes (CNTs) modified by sulfuric acid, titanium dioxide (TiO(2)) and composite of CNTs and TiO(2). RESULTS: More than 360 h contact time was needed to completely adsorb 3 mg L(-1) of Cr(VI) by CNTs, indicating that the rate of adsorption by CNTs alone was slow. The reaction time approaching equilibrium depended on the Cr(VI) concentration. XPS analysis of CNTs after adsorbing Cr(VI) showed that the Cr(VI) on the surface of CNTs was partially reduced to Cr(III). A 3 mg L(-1) solution of Cr(VI) was fully photocatalyzed by commercial TiO(2) (Degussa P25) in less than 0.5 h under UV irradiation. Unlike P25, reduction by another commercial TiO(2) (Hombikat UV100) took 4 h and more than 2 h were necessary for reduction by the composite. Thus the efficiency of Cr(VI) photo-reduction by the composite was lower than by TiO(2), but higher than that by CNTs. XPS analysis of TiO(2) and composite showed the existence of both Cr(VI) and Cr(III) on their surfaces. CONCLUSION: In contrast to TiO(2), the reduction rate of aqueous Cr(VI) using CNTs as adsorbent was slow. P25 had a markedly higher photocatalytic efficiency than the composite or UV100 alone. Using P25 to reduce aqueous Cr(VI) has a higher potential for practical application. The diameters of TiO(2) and CNTs and the ratio of TiO(2)/CNTs are key problems in the preparation of TiO(2)/CNTs composite. (C) 2011 Society of Chemical Industry[[note]]SC

    Going Beyond Counting First Authors in Author Co-citation Analysis

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    The 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

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    “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

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    We 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

    Enhancing resilience by reducing critical load loss via an emergent trading framework considering possible resources isolation under typhoon

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    Leveraging distributed resources to enhance distribution network (DN) resilience is an effective measure in response to natural disasters. However, the willingness and economy of distributed resources are typically ignored. To address this issue, this paper proposes an emergent trading framework that uses parking lots (PLs) as resources to provide power support to critical loads (CLs) in a blackout due to typhoons. In this trading framework, an evolutionary Stackelberg game-based trading model is established to consider maximizing all stakeholders' economic benefits, considering possible resources isolation under typical fault scenarios caused by typhoons, and a benefit allocation mechanism is proposed for all stakeholders to motivate all stakeholders to participate in the trading. This framework allows that critical loads could reduce their load loss, parking lots could receive adequate compensation to stimulate them to participate in the trading, and distribution utility could ensure its economic benefits. Furthermore, an iterative evolutionary-Stackelberg solution set-up is applied to obtain the equilibria of the proposed framework. Simulation results on the modified IEEE 69-bus test system and IEEE 123-bus test system reveal the validity of the proposed method

    Dispelling the Myths Behind First-author Citation Counts

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    We 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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