1,720,965 research outputs found
Ceria Based Materials with Enhanced OSC Properties for H2 Production by Water Splitting Reaction
No full textCerium based oxides have recently emerged as highly attractive choice for two-steps thermochemical water splitting cycles for H2 production because of their ability to reversibly store and release lattice oxygen in inert conditions between 1573-1773 K. A novel surfactant-assisted method was developed in our laboratory to enhance OSC (oxygen storage capacity) properties and thermo stability of Ce0.15Zr0.79Nd0.04La0.02O2-δ composition. The developed procedure was used to prepare other compositions with differents amount of CeO2, pure and doped with La and Nd. All prepared compositions were subjected to different aging treatments at different temperature under air and N2 atmosphere. The textural, structural and OSC properties were studied and the reactivity versus water splitting at 1073K was tested. The results obtained highlight that the reactivity depends on the temperature of treatments and on the composition. The best result was obtained for Ce0.5Zr0.5O2 composition treated at 1673K in N2 (308 μmol H2/g of CeO2). Further studies are in progress to investigate the correlation between the structure and the reactivity of these oxides
Synergic interaction between ceria and tin in SOFC anodes
No full textCeria and tin oxide were infiltrated in samariadoped ceria (SDC) anodes for use in intermediatetemperature solid oxide fuel cells (IT-SOFCs). It was found that ceria is able to stabilized tin as a molten metal in a reducing atmosphere up to 973 K, by preventing its coalescence and segregation. Moreover, electrochemical tests showed that the addition of tin significantly improves the performance of ceria towards the oxidation of hydrogen and methane. Impedance spectra suggested that the addition of tin affects conduction as well as reaction kinetics in the anode
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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