1,720,956 research outputs found
Catalytic nitroxidation of 1-methylnaphthalene I. Preparation, characterisation and NO surface interactions of chromia/alumina-based catalysts
No full textAcid-base features of ex-hydrotalcites Mg-containing and Mg-free mixed oxides
No full textCuNiAl and MgCuNiAl mixed oxides (Cu2+/Ni2+ = 0.29 and 0.32 mol/mol) were obtained from layered double hydroxide precursors (M 2+/Al3+ = 2 mol/mol) synthesized by pH-controlled co-precipitation. After structural and textural characterization (by X-ray diffraction and N2 physisorption, respectively), the acid and basic features of the mixed oxides were investigated by adsorption microcalorimetry. NH3 and CO2 were used for probing the acid and basic features, respectively. By the use of temperature-programmed technique, the redox features of the oxides were investigated as well. The behaviour of the oxides as catalysts for the conversion of 4-methylpentan-2-ol at 448, 473, and 523 K under atmospheric pressure was studied in a fixed-bed reactor. The dehydration products distribution and the relative extents of the dehydration and dehydrogenation reactions are discussed in terms of the possible occurrence, depending on the lack or presence of Mg in the oxide and the reaction temperature, of either acid-base-governed E1 and E2 mechanisms or Cu-promoted reaction pathways
Characterization of the active sites in MgNiAl mixed oxides by microcalorimetry and test reaction
No full textIn this study, MgNiAl mixed oxides derived from layered double hydroxide precursors were prepared by pH-controlled co-precipitation. Three samples were prepared with a (Mg 2+ + Ni 2+)/Al 3+ ratio of 2 and a Ni 2+/ Mg 2+ with ratios of 0.22, 0.47, and 4.05. The structural, textural and redox features of the oxides were investigated by a variety of techniques, including X-ray diffraction, transmission electron microscopy, N 2 physisorption, and temperature-programmed reduction. The acid and base properties were assessed by NH 3 and CO 2 adsorption microcalorimetry, respectively. The acid-base features were also investigated by testing the catalytic behaviors of the oxides for the conversion of 4-methylpentan-2-ol under both mild and stressed conditions. The reactant alcohol can undergo dehydration into 4-methylpent-1-ene, 4-methylpent- 2-ene, and skeletal isomers of C 6-alkenes, as well as dehydrogenation to 4-methylpentan-2-one and higher ketones, the product selectivity being governed by the concentration and strength of the acid and base sites. Comparison between the calorimetric and test reaction results is discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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