1,720,958 research outputs found
Functionalized TUD-1: Synthesis, characterization and (photo-)catalytic performance
No full textThe new mesoporous material; TUD-1 is chosen of which the synthesis, characterization, and functionalization for (photo)-catalytic performance are extensively investigated in this study. The synthesis of the new catalytic materials M TUD-1 (M = Ti, V, Cr, Mo, Fe, Co and Cu) is carried out through an easy one-pot synthesis procedure, mainly depends on the addition of a small organic, cost-effective template triethanolamine together with the desired metal source and the silica source. The product; M-TUD-1 is a three-dimensional, open structured mesoporous siliceous material. The amount of metal added during the synthesis played the essential rule in the formation of different active site species (i.e. isolated, nano-particles and/or bulk crystals of metal oxide) in the TUD-1 matrix. The prepared materials are characterized by various characterization techniques (physical: X-ray diffraction, N2 sorption measurements SEM and HR-TEM and chemical: 29Si NMR, elemental analysis, and UV-VIS- and Raman spectroscopy). And their catalytic performance is tested in four different catalytic applications: selective photo-oxidation of propane, selective oxidation of cyclohexane, Friedel-Crafts benzylation of benzene, and laughing gas (N2O) decomposition. Indeed, the three-dimensional open structure of M-TUD-1 increases the accessibility to the active sites and hence, the (photo-)catalytic performance of M TUD-1 is ranked against their peers under comparable conditions: In the photo-oxidation of propane, Ti-TUD-1 exhibits a 2-2.5 times higher acetone selectivity than commercial TiO2. In the same reaction, Cr-TUD-1 is 5-6 times more active than SiO2 supported Cr at the same chromium loading. An important observation is that certain products (acetone, water) are less strongly adsorbed on TUD-1 than on zeolite-Y. In Friedel-Crafts benzylation of benzene, Fe-TUD-1 shows unique activity, which is benchmarked against other reported micro- (ZSM-5) and mesoporous systems (MCM-41 and HMS). In N2O decomposition, the activity reported over M-TUD-1 is less than reported for analogous M-ZSM-5. However, M-TUD-1 shows a better behaviour as a support than other mesoporous materials e.g. M-SBA-15, M-MCM-41. In conclusion, the present study shows that TUD-1 is not only just an interesting, but also an important support which can contain, in a controllable way, different active sites species, and that it can play a significant role in different catalytic application.Applied Science
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
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