1,720,959 research outputs found
Development of environmental micro-sensors based on functionalized CVD graphene : detection of lead in aqueous media using field effect transistors (FETs) and electrochemical sensors
No full textCette thèse porte sur le développement de nouveaux capteurs (GrFET) utilisant les transistors à effet de champ (FET) intégrant comme élément de détection du graphène monocouche obtenu par dépôt chimique en phase gazeuse (CVD) dans le but de détecter les micropolluants des eaux, en particulier le plomb Pb(II). Actuellement, la qualité des eaux est évaluée par prélèvement sur site puis analyses en laboratoire, induisant des coûts et des délais incompatibles avec un suivi des micropolluants compatibles avec les préconisations des directives européennes. Le développement de nouvelles générations de capteurs, comme les microcapteurs de type GrFET, ou de microcapteurs électrochimiques à électrode de graphène CVD (GrE) pourrait permettre un déploiement à grande échelle intensifiant les points de mesure et leur fréquence s'ils répondent au cahier des charges de la DCE notamment en termes de limites de détection. Pour atteindre ces limites, il est nécessaire d'améliorer la sensibilité et la sélectivité des capteurs FET ou électrochimiques. Cette amélioration peut être obtenue par une sélection minutieuse du matériau de l'électrode et de la fonctionnalisation de sa surface. Dans les travaux présentés, le développement de capteurs environnementaux à base de graphène CVD doit répondre à cette problématique de détection sur site. La première phase de développement des capteurs, notamment du FET, a porté sur l'optimisation des différentes étapes de fabrication du GrFET en salle blanche et à la caractérisation des propriétés électriques et optiques du de la couche graphène du transistor GrFET. L'expérience acquise dans la préparation des FET a permis d'obtenir les microélectrodes utilisées ensuite pour le développement d'un microcapteur électrochimique. Le graphène des GrFET et des électrodes GrE a ensuite été fonctionnalisé par des groupements dicarboxyphenyl via la réduction électrochimique d'un sel de diazonium afin d'augmenter la sensibilité aux ions Pb(II). Les deux technologies de capteurs ont ensuite été utilisées pour la détection du plomb Pb(II) dans l'eau. Le microcapteur GrE a permis d'atteindre une limite de détection (LOD) de 3,4 nM, soit plus de dix fois inférieure au seuil imposé par la DCE, et une limite de quantification (LOQ) de 11,4 nM. Concernant le microcapteur GrFET, le développement d'un design original permettant le greffage par les sels de diazonium des surfaces de graphène de quinze FET dans des conditions identiques a conduit à l'étude de nouvelles méthodes de transduction du signal, via la mesure de la résistance de la couche de graphène ou la mesure de la position du point de Dirac. Les premiers résultats obtenus ont montré une limite de détection de 0.1 µM. Ces résultats sont une preuve de concept originale de l'application d'un FET graphène CVD à la détection du plomb Pb(II) en milieu aqueux.This thesis focuses on the development of new sensors (GrFETs) using field effect transistors (FETs) incorporating monolayer graphene obtained by chemical vapor deposition (CVD) as the detection element, with the aim of detecting micropollutants in water, in particular lead Pb(II). At present, water quality is assessed by taking samples on site and then analysing them in the laboratory, resulting in costs and timescales that are incompatible with micropollutant monitoring in line with the recommendations of European directives. The development of new generations of sensors, such as GrFET-type micro-sensors, or electrochemical micro-sensors with graphene CVD electrodes (GrE) could enable large-scale deployment, increasing the number and frequency of measurement points if they meet WFD specifications, particularly in terms of detection limits. To reach these limits, it is necessary to improve the sensitivity and selectivity of FET or electrochemical sensors. This improvement can be achieved by carefully selecting the electrode material and functionalising its surface. In this work, the development of CVD graphene-based environmental sensors is intended to address this problem of on-site detection. The first phase in the development of the sensors, in particular the FET, involved optimising the various stages in the manufacture of the GrFET in a clean room and characterizing the electrical and optical properties of the graphene layer of the GrFET transistor. The experience gained in the preparation of FETs was used to obtain the microelectrodes that were then used to develop an electrochemical microsensor. The graphene of the GrFETs and GrE electrodes were then functionalised with dicarboxyphenyl groups via the electrochemical reduction of a diazonium salt in order to increase sensitivity to Pb(II) ions. The two sensor technologies were then used to detect Pb(II) lead in water. The GrE microsensor achieved a limit of detection (LOD) of 3.4 nM, more than ten times less than the threshold imposed by the WFD, and a limit of quantification (LOQ) of 11.4 nM. With regard to the GrFET microsensor, the development of an original design enabling the grafting by diazonium salts of the graphene surfaces of fifteen FETs under identical conditions, has led to the study of new signal transduction methods, via the measurement of the resistance of the graphene layer or the measurement of the position of the Dirac point. The first results obtained showed a detection limit of 0.1 µM. These results are an original proof of concept for the application of a CVD graphene FET to the detection of Pb(II) lead in aqueous media
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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