1,720,960 research outputs found
Synthesis and characterisation of platinum(II) methyl complexes and their reactivity towards carbon-hydrogen (C-H) and carbon-halogen bonds (C-X)
No full textWithin this thesis, the syntheses of novel Pt⁽ᴵᴵ⁾ complexes that show reactivity towards carbon-hydrogen and carbon-halogen bonds is explored. Understanding the nuances of fundamental reactivity is important for catalyst design. These nuances allow for the development of novel systems capable of tackling challenging reactions such as alkane activation and functionalisation. Chapter 1 gives an overview of the current understanding of the mechanisms for C-H activation of alkanes and how the communities understanding has changed over the last 20 years. In chapter 2 the intermolecular oxidative addition of aryl halides to Pt⁽ᴵᴵ⁾ complexes is presented. The work in chapter 2 forms part of a proposed catalytic cycle for methane functionalisation, using aryl halides as oxidants. The oxidative addition of aryl halides to Pt⁽ᴵᴵ⁾ complexes has so far only been reported for aryl halides that are tethered to the ligand backbone. The work in chapter 2 therefore constitutes a significant advance in the reactivity of aryl halide chemistry with platinum. Novel ligand design and synthesis of new platinum complexes targeted towards small molecule activation is presented in chapter 3. The new ligands provide an entry into the synthesis of (hetero)bimetallic complexes that could show activity in cascade or tandem reactions. The use of bimetallic complexes is important for tailoring the reactivity of two catalysts simultaneously in the same molecule allowing for a higher degree of control over a reaction or multiple reactions in the same flask. The C-H activation of pyridine via the formation of Pt-Pt bonded bimetallic species is shown in chapter 4. Furthermore, a detailed computational and experimental study into the donor-acceptor nature of the Pt-Pt bond shows how bimetallic complexes of platinum could be used in challenging C-H activation reactions. Chapter 5 provides a summary of the work in this thesis and gives new avenues for the continued development of new platinum compounds for small molecule activation reactions.Science, Faculty ofChemistry, Department ofGraduat
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
Single-Crystal to Single-Crystal Synthesis of a Gold(I)-Ammonia Complex and H/D Exchange In Crystallo with D2O
No full textSingle-crystal to single-crystal solid/gas reactivity of [LAu(C2H4/CO)][BArF4] [L = tris-2-(4,4'-di-tert-butylbiphenyl)phosphine] with NH3 or 15NH3 gives the ammonia complexes [LAu(NH3/15NH3)][BArF4]. Solid-gas H/D exchange with D2O vapour gives the ND3 isotopologues, while reaction with HCl vapour affords [1-Cl]/[15NH4][BArF4], identifying a lattice encapsulated ammonium as a plausible intermediate species for H/D exchange with D2O by a proton rebound mechanism
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
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