1,720,996 research outputs found
Special Catalysts and Processes: Biocatalysis and Enzyme-Analogous Processes
No full textSchultz C, Gröger H, Dinkel C, Drauz K, Waldmann H. Special Catalysts and Processes: Biocatalysis and Enzyme-Analogous Processes. In: Cornils B, Herrmann WA, eds. Applied Homogeneous Catalysis with Organometallic Compounds. Vol 2. 2.nd ed. Weinheim: Wiley-VCH-Verlag; 2002: 872-911
The synthesis, photochemistry & electrochemistry of dithienylethene switches & their organometallic complexes
Full text linkChapter one presents a detailed literature survey on dithienylcyclopentene switches, describing their synthesis, properties and applications. The photochromic and electrochromic effects of functionalising such switching units with metal complexes, is then discussed. Finally, an introduction to cobalt carbonyl complexes is given, with
an outline of the photochemical and electrochemical properties of such carbonyl complexes, as described in the literature.
Chapter two describes the synthetic procedures employed to prepare a number of dithienyl-perhydro- and perfluoro-cyclopentene switches, substituted with thienyl and
ferrocenyl moieties. The methods used to generate their corresponding Co2(CO)6 and Co2(CO)4dppm complexes are also described. 1H, 13C, 19F and 31P NMR techniques
were employed to analyse the resulting products. Elemental analysis and infra-red spectroscopy were also utilised, where applicable, to further characterise the final pure
compounds and the results are detailed in this chapter.
Chapter three describes the photochemical properties found for the thienyl-based dithienylcyclopentene switches and their corresponding cobalt carbonyl complexes.
The photochromic properties of the thienyl-based switches were monitored in the UVvis absorption spectra and the 1H NMR spectra. Their thermal stability, fatigue
resistance and fluorescent properties were also investigated. Furthermore, the effects of incorporating cobalt carbonyl moieties onto these thienyl-based switches, on their photocyclisation processes, are reported in this chapter.
Chapter four reports the photochromic behaviour of the ferrocenyl-based dithienylcyclopentene switches, as observed in the UV-vis and 1H NMR. Investigations into the thermal stability, fatigue resistance and fluorescent properties of these switches were carried out. The effects on the photochromic properties of the ferrocenyl-based switches, following the introduction of Co2(CO)6 and
Co2(CO)4dppm moieties, are also described in this chapter.
Chapter five focuses on the electrochemical properties of the thienyl-based dithienylcyclopentene switches. Electrochemically induced cyclisation/
cycloreversion processes were investigated through cyclic voltammetry and UV-vis spectroelectrochemistry techniques. Similar experiments were carried out for the cobalt carbonyl derivatives in order to examine the effects of the presence of the metal carbonyls on the oxidative ring-closing/opening abilities of the thienyl-based switches.
The effects of the oxidation processes on the cobalt carbonyl centres were also studied by monitoring the changes of the carbonyl stretches in the infra-red spectra.
Chapter six details the electrochemical behaviour of the ferrocenyl-based dithienylcyclopentene switches. The oxidative and reductive processes of these
switches were monitored in the cyclic voltammograms and UV-vis spectra of these switches in order to investigate if ring-opening/closing can be induced by electrochemical means. Their Co2(CO)6 and Co2(CO)4dppm complexes were also
subjected to similar experiments in order to determine the effects of introducing such metal carbonyl complexes on the electrochemical switching behaviour of these
ferrocenyl-based switches. IR spectroelectrochemical techniques were employed to examine the effects of oxidation processes on the cobalt carbonyl centres.
Chapter seven presents an overall conclusion of the results obtained, with an emphasis on a comparison between the effects of the thiophene substituents and the ferrocene
units, and the prospects of future work in this area is discussed. All publications are presented in the appendix
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
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