1,721,145 research outputs found
Tailoring the photoredox properties of organic dyes
No full textThe increasing interest for photoredox-induced processes has recently led to the exploitation of a large variety of inorganic and organic chromophores to trigger chemical reactions through photoinduced electron transfer (PET), generating highly reactive radical species. Until now, efforts in the field have been focused on the type of organic transformations, and rarely centred on the rational design of dyes featuring excited states with tailored photoredox properties for a given reaction. It is with this aim, that in this chapter we report on the general designing principle to engineer organic dyes (both as small molecules and macromolecules) featuring tailored photoredox properties. Understanding the behaviour of chromophores depicting programmed redox potentials in photo-triggered chemical transformations is crucial if one wants to rationally trigger novel organic reactions
Tetrachromophoric Systems Based On Rigid Tetraphenylmethane (TPM) and Tetraphenylethylene (TPE) Scaffolds
Full text linkTetraphenylmethane (TPM) and tetraphenylethylene (TPE) are among the most common rigid molecular architectures able to spatially arrange four peripheral functional groups. The aim of this Review is to provide a thorough description of the properties that supramolecular systems consisting of four chromophores (common supramolecular motifs, ligands, redox centers and conventional luminophores such as polypyridyl ligands, viologens, and azobenzene units) attached to TPM and TPE cores can show. Specifically, the photophysical properties of these molecules as well as the electronic interactions of the chromophores either in the ground or in the excited states will be highlighted and discussed, outlining the relationship among cores and outer subunits
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
Shining Light on TiIV Complexes: Exceptional Tools for Metallaphotoredox Catalysis
Full text linkTitanium is one of the most abundant and environmentally innocuous metals. Ti-based organometallic compounds have long been used as versatile homogeneous catalysts in synthetic chemistry and still remain highly attractive for the development of sustainable transformations. With the emerging role of photoredox catalysis, the selectivity of the radical initiation in electron transfer-mediated reactions has been shown to be fundamental in terms of synthesis efficiency. Recent examples have displayed the effectiveness of inorganic and organic chromophores at the excited state in triggering the redox chemistry of TiIV/III complexes. In this minireview, we will illustrate the underlying principles and practicability of these – still uncommon – metallaphotoredox catalytic reactions
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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