1,720,969 research outputs found
Turning Pd-catalysed direct C–H arylation of thiophene derivatives into green : industrial wastewater as an effective reaction medium
Full text linkThe Pd-catalysed direct C-H arylation of thiophene derivatives, appealing for technological application, is performed under green conditions using water as the sole reaction medium. The reaction is independent of the grade of the water, thus enabling the virtuous repurposing of low-purity grade industrial wastewater, allowing one to bring the process to the gram scale and improve its green metrics
Modulation of [CuOH/O]+ Properties in [2,2′-Bipyridine]2 Homoleptic Complexes through Substitution at the 6,6’ Position by Methyl Groups
Full text linkIn this paper, data from a DFT-based computational study on the reactivity of [Cu(2,2′-S-bpy)2]+PF6- (S indicating substitution by methyl groups at the 6 and/or 6’ position and ranging from 0 to 100% through 50%) homoleptic complexes based toward tButOOH were presented. Computational results, supported by cyclic voltammetry analysis, prove the feasibility of finely tuning the chemical properties of the complexes and their reactivity by means of insertion of methyl moieties in selected positions within the bipyridine scaffold
Molecular and crystal structures obtained preparing Cu-bipyridine complexes in presence of chlorinated solvents in oxidizing environment
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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
A Raman lens on the active sites in the oxygenation of cyclohexene catalyzed by a Cu-bipyridine homoleptic complex
No full textIn [Cu(6,6’-dimethyl-2,2’-bipyridine)2](PF6) (hereafter coded as CuBPA) the presence of methyl moieties allows a stabilization of Cu(I) form, enabling an easier switching between Cu(I) and Cu(II) that is of particular interest in catalysis. In this contribution, resonant Raman spectroscopy (with simultaneous UV-Vis acquisition) supported by DFT calculations is employed as a lens to precisely monitor the metal organic complex throughout its redox cycle and to identify its active species. As a model reaction, the CuBPA-mediated oxygenation of cyclohexene (as the reductant/substrate) by means of tert-Butyl hydroperoxide (as the oxidant) is selected. In this context, 266 nm laser turns out to be quintessential for the characterization of the oxidized form (Ox-CuBPA) and to follow the system evolution throughout the redox cycle, although it fails in giving an unambiguous identification and quantification of reaction products. Aiming at this, catalytic tests are performed under conditions that replicate the spectroscopic experiments. 2-cyclohexene-1-ol and 2-cyclohexene-1-one are identified as the dominant products, proving a promising catalytic activity of CuBPA in partial oxidation reactions
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
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