1,720,991 research outputs found
Synthèse et caractérisation de molécules photo-actionnables pour le contrôle optique d'intéractions supramoléculaires
No full textCe travail est consacré à la synthèse, à la caractérisation et aux études photophysique de nouveaux dithienylethenes (DTE) a base de chromophores organometalliques et organiques vers le contrôle tout optique d’interactions supramoléculaires. Grâce à un design original du DTE, les interactions supramoléculaires sont contrôlées optiquement par un mouvement moléculaire. Après une étude bibliographique présentant les propriétés vastes des DTE et leur efficacité à photo-contrôler les propriétés de luminescence de chromophores variés, la première stratégie vers la photo-modulation de la luminescence exciplexe proche infra-rouge de complexes de platine(II) est présentée. Les monocomplexes de Pt(II) à bases de DTE ont étés obtenus et sont entièrement caractérisés et leur propriétés photochromes et photophysiques sont démontrées. Les DTE présentent une stabilité optique et montrent une photo-modulation efficace de la luminescence des mono-complexes de platine(II). La troisième partie de ce travail vise à obtenir des DTE à bases de pyrene pour le contrôle tout-optique d’excimer statique. Deux nouveaux DTE bispyrene ont étés obtenus et leur caractérisation complète est également présentée. Ces DTE présentent une efficacité de la réaction de photochromisme, ainsi qu’une bonne extinction de la luminescence excimère du pyrène dû à un mouvement moléculaire. Les études photophysiques révèlent la possibilité d’utiliser l’absorption à un- et deux-photons afin d’atteindre un système de lecture non destructif, présentant un intérêt pour les applications de stockage d’informations. La quatrième partie de ce travail est complémentaire à la précédente et présente la stratégie et la synthèse vers l’obtention de DTE atropoisomères pour le contrôle optique de propriétés chiroptiques, en introduisant de l’encombrement stérique sur le DTE.This work is devoted to the synthesis, characterization and photophysical studies of novel organometallic or organic chromophores-based dithienylethenes (DTE) towards the all-optical control of supramolecular interactions. Thanks to an original design of the DTE, the supramolecular interactions are optically controlled by molecular movement. After a bibliographic study presenting the vast properties of DTEs and their efficiency to photo-control the luminescence properties of various chromophores, the first strategy towards the photo modulation of the near-infrared exciplex luminescence of platinum(II) complexes is presented. DTE-based Pt(II) mono-complexes have been obtained, are fully characterized and their photochromic and photophysical properties are demonstrated. DTEs exhibited optical stability and showed effective photo-modulation of the luminescence of platinum(II) mono-complexes. The third part of this work aims to obtain pyrene-based DTEs for the all-optical control of static excimer. Two new bispyrene DTEs have been obtained and their complete characterization is also demonstrated. These DTEs present an efficient photochromic reaction, as well as a good extinction of the excimer luminescence of the pyrene due to a molecular movement. Photophysical studies reveal the possibility of using one- and two-photon absorption to achieve a non-destructive readout system, of interest for data storage applications. The fourth part of this work is complementary to the previous one and presents the strategy and the synthesis towards atropoisomeric DTEs for the optical control of chiroptical properties, by introducing steric hindrance on the DTE
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
Synthèse et caractérisation de systèmes photo-activables
No full textCette recherche se concentre sur la synthèse d'organométalliques et de chromophores organiques vers les systèmes tout-optiques. L'objectif global de cette thèse est d'explorer de nouvelles architectures moléculaires qui peuvent répondre efficacement à des stimuli lumineux externes, conduisant à des modulations de leurs propriétés physico-chimiques. La stratégie proposée est basée sur la préparation d'un matériau moléculaire qui présente des réponses optiques non linéaires (ONL) stables et activables par la lumière et/ou des propriétés de luminescence. Après un examen approfondi de la littérature sur la luminescence photocommutable et les propriétés optiques non linéaires, cette recherche a porté sur deux projets distincts : i) le greffage en surface de complexes organiques et organométalliques pour moduler les propriétés OLN, et ii) l'étude de nouveaux colorants rhodamine à base de diaryléthènes (DAE) en solution, mettant en évidence leurs capacités de photocommutation et de chimio-commutation. Le premier projet est discuté dans les deuxième et troisième parties de ce travail. La deuxième partie montre la synthèse de complexes de platine cyclométalisés et leur greffage sur la surface. La troisième partie vise à explorer les NLO-phores organiques et à mettre l'accent sur le développement de commutateurs moléculaires réagissant à la lumière. Dans la quatrième partie de cette recherche, une attention particulière est consacrée à la synthèse et à la caractérisation de nouveaux diaryléthènes incorporant un colorant rhodamine fluorescent. Ces nouveaux composés ont été spécifiquement conçus pour présenter un comportement remarquablement efficace de photocommutation et de chimio-commutation.This research focuses on the synthesis of organometallics and organic chromophores towards the all-optical systems. The global objective of this thesis is to explore novel molecular architectures that can efficiently respond to external light stimuli, leading to modulations in their physicochemical properties. The strategy proposed is based on the preparation of a molecular material that display stable and light-activatable nonlinear optical (NLO) responses and/or luminescence properties. Following a comprehensive review of the literature on photo-switching luminescence and non-linear optical properties, this research pursued two distinct projects: i) The surface grafting of organic and organometallic complexes to modulate NLO properties, and ii) The investigation of novel diarylethenes (DAE)-based rhodamine dyes in solution, showcasing their photo and chemo-switching capabilities. The first project is discussed in the second and third part of this work. The second part shows the synthesis of cyclometalated platinum complexes and their grafting on surface. The third part aims to explore organic NLO-phores and emphasize the development of molecular switches responsive to light. In the fourth part of this research, significant attention is devoted to synthesizing and characterizing novel diarylethenes incorporating a fluorescent rhodamine dye. These newly developed compounds were specifically designed to exhibit remarkably efficient photo and chemo-switching behavior
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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