1,721,100 research outputs found
Pedro Robina and Juan Gómez de Vidaurre: unpublished accounts of the earthquake of May 24, 1751 in Concepción, Chile
No full textFil: Stewart, Daniel M. Pontificia Universidad Católica de Valparaíso; Chil
Well-defined Metal-Organic Framework (MOF) based catalysts for the direct utilisation of CO2
No full textGiven current environmental concerns over greenhouse emissions, the need for technologies capable of the fixation and utilisation of carbon dioxide (CO2) remains a pivotal area of research. Despite this requirement, there remains a distinct shortage in research which adequately utilises CO2 as a direct C1 feedstock material. One widelyreported method, the catalytic ring-opening copolymerisation (ROCOP) of epoxides and CO2 to form poly(alkylene) carbonates, provides a promising and more sustainable route to polyurethanes, a material that represents a billion USD industry and finds ubiquitous usage across many commercial sectors. Providing an alternative to the traditional ringopening polymerisations (ROP) of cyclic carbonate monomers or toxic polycondensations with trans-diols and phosgene, the ROCOP pathway not only offers a safer, more sustainable route to polycarbonates, but directly consumes CO2 and reduces our dependence on petrochemical feedstocks. To date, this process has been catalysed predominantly by homogeneous metalcomplexes, with scarce few examples of heterogeneous systems existing within the literature. Motivated by the distinct lack of heterogeneous counterparts, the development of suitable MOF-based catalysts has been established. Through the analysis of the current homo- and heterogeneous catalysts, structure-activity correlations pertaining to their Abstract ii activity towards specific stages of the copolymerisation mechanism have been realised, providing a catalyst design rationale on which this thesis is built. Using these correlations, a suitable MOF - MIL-100(Sc) - was synthesised, characterised and shown to provide unprecedented activity towards the copolymerisation under far milder conditions than those previously reported. To rationalise the source of the activity, in situ and operando characterisation techniques, in hand with computational calculations, have been utilised to reveal the nature of the two active sites within the MIL-100 architecture. Unambiguous evidence concerning the role of each site in the activation of CO2 and the epoxide is presented; evidence that has eluded the literature of copolymerisation catalysts. Utilising these findings, further development of the catalyst was provided in the form of a surface-engineering protocol, successfully optimising active site populations at the surface of the MOFs through synthetic manipulation with monocarboxylic modulators, and through a mixed-metal strategy in which isomorphous substitution of the constituent metals was achieved. Through these strategies, catalysts capable of far superior catalytic activity compared to the current commercial catalyst was achieved. Through a range of complimentary characterisation techniques, this activity has been attributed to fundamental catalysis concepts, highlighting the importance of purposeful catalyst design and the synergy between the catalyst morphology and the active site
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
