1,720,970 research outputs found
Elaboration de systèmes moléculaires multi-chromophoriques pour l'électronique moléculaire
No full textAu cours des dernières décennies, de nombreux efforts se sont focalisés sur la synthèse, la modification et l’utilisation de systèmes moléculaires multi-adressables. Afin d’élaborer de tels systèmes capables de répondre à des stimulations de différentes natures (par exemple : photon, électron, proton, etc…) les deux principales stratégies consistaient à ce jour à connecter différents types d’unités stimulables soit par liaison covalente soit par dispersion au sein d’assemblages supramoléculaires. Au cours de cette thèse, nous nous sommes attachés à développer une nouvelle approche basée sur l’utilisation d’un unique switch multi-mode : les indolino-oxazolidine (BOX). En effet, cette unité est capable de commuter entre deux états métastables (ouvert et fermé) et ce de façon indifférenciée par application d’une stimulation lumineuse, électrochimique ou encore par variation du pH. En suivant une première stratégie, deux unités BOX ont été connectées via l’utilisation d’un simple système conjugué linéaire tels qu’une unité bithiophène et un enchainement EDOT-Thiophène-EDOT (ETE) comme espaceur. Nous avons démontré que ces systèmes multi-stimulables sont capables de commuter de façon pas à pas entre 3 états métastables différents et ce quel que soit la nature du stimulus. Afin de démontrer les nombreuses possibilités de cette approche et augmenter le nombre d’états métastables, 3 unités BOX ont été connectés par l’utilisation de systèmes conjugués plus élaborés permettant ainsi de conduire à des interrupteurs moléculaires capables de présenter jusqu’à 4 états différents. En complément de cette approche purement organique, une seconde stratégie a consisté à fonctionnaliser différents ligands azotés par au moins une entité BOX afin d’élaborer des systèmes plus complexes par chimie de coordination avec des ions métalliques de zinc et de ruthénium. Les ligands préparés ainsi que les complexes correspondants ont été pleinement caractérisés et leur addressabilité sous stimulation chimique, électrique et lumineuse étudiée.Over the past decade many efforts have been focused on the synthesis, modification and application of multi-responsive molecular systems. Up to now, two main strategies have been conducted to elaborate such systems: either by connecting different molecular switches through covalent links or by mixing them within supramolecular assemblies to obtain multiresponsiveness through the combination of various stimulations (i.e., photon, electron, proton, etc…). In thisthesis, we report a different approach based on the employment of identical indolinooxazolidine (BOX) unit as multi-modal switch. Indeed, the opening of the oxazolidine ring can be reversibly and selectively achieved either under UV irradiation, electrochemical stimulation or acidity changes. According to our first strategy, two BOX units were connected around a simple linear aromatic plate forms, such as bithiophene and EDOT-Thiophene-EDOT unit as spacer. Interestingly, these systems are able to commute between 3 different metastable states in a stepwise manner with all kinds of stimulations. Going further, in order to promote the metastable states, it was possible to increase the number of BOX by connecting three of them on more elaborated pi systems which are potentially able to exhibit up to four discriminate metastable states. Complementary to that, a second strategy was to synthesize various nitrogen ligands functionalized by at least one BOX unit and their coordination chemistry with zinc and ruthenium metals. The response of the ligands as well as their corresponding complexes under photo, electro and acidic stimulation were also investigated and fully characterized
Elaboration de systèmes moléculaires multi-chromophoriques pour l'électronique moléculaire
No full textOver the past decade many efforts have been focused on the synthesis, modification and application of multi-responsive molecular systems. Up to now, two main strategies have been conducted to elaborate such systems: either by connecting different molecular switches through covalent links or by mixing them within supramolecular assemblies to obtain multiresponsiveness through the combination of various stimulations (i.e., photon, electron, proton, etc…). In thisthesis, we report a different approach based on the employment of identical indolinooxazolidine (BOX) unit as multi-modal switch. Indeed, the opening of the oxazolidine ring can be reversibly and selectively achieved either under UV irradiation, electrochemical stimulation or acidity changes. According to our first strategy, two BOX units were connected around a simple linear aromatic plate forms, such as bithiophene and EDOT-Thiophene-EDOT unit as spacer. Interestingly, these systems are able to commute between 3 different metastable states in a stepwise manner with all kinds of stimulations. Going further, in order to promote the metastable states, it was possible to increase the number of BOX by connecting three of them on more elaborated pi systems which are potentially able to exhibit up to four discriminate metastable states. Complementary to that, a second strategy was to synthesize various nitrogen ligands functionalized by at least one BOX unit and their coordination chemistry with zinc and ruthenium metals. The response of the ligands as well as their corresponding complexes under photo, electro and acidic stimulation were also investigated and fully characterized.Au cours des dernières décennies, de nombreux efforts se sont focalisés sur la synthèse, la modification et l’utilisation de systèmes moléculaires multi-adressables. Afin d’élaborer de tels systèmes capables de répondre à des stimulations de différentes natures (par exemple : photon, électron, proton, etc…) les deux principales stratégies consistaient à ce jour à connecter différents types d’unités stimulables soit par liaison covalente soit par dispersion au sein d’assemblages supramoléculaires. Au cours de cette thèse, nous nous sommes attachés à développer une nouvelle approche basée sur l’utilisation d’un unique switch multi-mode : les indolino-oxazolidine (BOX). En effet, cette unité est capable de commuter entre deux états métastables (ouvert et fermé) et ce de façon indifférenciée par application d’une stimulation lumineuse, électrochimique ou encore par variation du pH. En suivant une première stratégie, deux unités BOX ont été connectées via l’utilisation d’un simple système conjugué linéaire tels qu’une unité bithiophène et un enchainement EDOT-Thiophène-EDOT (ETE) comme espaceur. Nous avons démontré que ces systèmes multi-stimulables sont capables de commuter de façon pas à pas entre 3 états métastables différents et ce quel que soit la nature du stimulus. Afin de démontrer les nombreuses possibilités de cette approche et augmenter le nombre d’états métastables, 3 unités BOX ont été connectés par l’utilisation de systèmes conjugués plus élaborés permettant ainsi de conduire à des interrupteurs moléculaires capables de présenter jusqu’à 4 états différents. En complément de cette approche purement organique, une seconde stratégie a consisté à fonctionnaliser différents ligands azotés par au moins une entité BOX afin d’élaborer des systèmes plus complexes par chimie de coordination avec des ions métalliques de zinc et de ruthénium. Les ligands préparés ainsi que les complexes correspondants ont été pleinement caractérisés et leur addressabilité sous stimulation chimique, électrique et lumineuse étudiée
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
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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