1,720,957 research outputs found
Innovative catalysts for H2 conversion to SNG via CO2 methanation
No full textThe depletion of fossil fuels increased the interest towards the power-to-gas technologies for the conversion of energy excess (such as photovoltaic energy) in valuable chemicals. In this direction, the CO2 hydrogenation to substitute natural gas strikes the double target to reduce a greenhouse emission and to exploit solar energy surplus. These papers addressed on the study of innovative catalysts for the CO2 hydrogenation (Sabatier reaction), by paying attention on the role of active phase and chemical support. In particular, the effect of nickel loading was investigated, evidencing that in one hand the higher amount of active specie increased the activity and reduced the onset temperature of the catalyst, in the other hand too large loadings could suppress the dispersion of the metal, thus reducing the CO2 conversion. The employing of ceria and ceria-zirconia as catalytic supports improved the sample reducibility, so increasing the CO2 conversion and reducing the activation temperature of the catalytic system; in particular, CeO2-ZrO2 sample showed a higher selectivity towards the Sabatier reaction. The high exothermicity of the reaction is better managed by employing highly conductive structured catalysts that assured an enhanced redistribution of the heat in the whole reaction volume, thus assuring higher conversion values and mainly higher selectivity towards methane production
Study of the role of chemical support and structured carrier on the CO2 methanation reaction
No full textPower-to-Gas (PtG) technology is particularly interesting because it is based on a mature technology such as the methanation process, based on the established Sabatier reaction. The industrial applicability of such technology is severely limited by the huge exothermicity of the process, that affects the catalyst stability. The aim of this work was to investigate the effect of the chemical and physical support for Sabatier reaction. Nickel based samples were prepared, by deposing the active metal on alumina (as a commercial reference), ceria and a cerium-zirconium mixed oxide supports. The catalytic activity tests confirmed that rare heart oxides supports strongly improved the catalytic performances, both in terms of CO2 conversion and selectivity to CH4, probably due to the basic nature of such supports. The CeZr-based formulation was then deposited on structured carriers with highly thermal conductivity, like a silicon carbide monolith (SiC) and an aluminium foam. Experimental achievements highlighted the effect of conductive carriers on the temperature profile along the reactor volume. SiC monolith and aluminium foam are able to guarantee a flattest thermal profile than the powder, thus in one and ensuring a higher conversion of carbon dioxide, in the other hand strongly suppressing side-reaction contribution, therefore maximising the selectivity to methane
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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