1,720,954 research outputs found
Synthesis of terpene-based amphiphilic copolymers as stabilizers of film-forming waterborne latex prepared from biobased 1,3-diene terpene monomers.
No full textCe projet de thèse vise à réduire l'empreinte carbone en valorisant des produits issus de la biomasse pour synthétiser différentes classes de matériaux polymère, plus particulièrement des copolymères amphiphiles comme stabilisants pour l’élaboration de latex. Développer une nouvelle génération de matériaux biosourcés est au cœur du projet pour soutenir une économie circulaire. En valorisant les principes de la chimie verte, l'objectif final est de substituer les produits issus de ressources fossiles dont la production participe aux émissions de gaz à effet de serre, par des produits provenant de la biomasse renouvelable.La première partie de ce travail de thèse vise à synthétiser des copolymères amphiphiles à base de terpènes, produits issus de la biomasse forestière, par une stratégie de couplage de ces molécules hydrophobes sur un squelette polymère hydrophile de type poly(acide acrylique). Ce dernier a été synthétisé par polymérisation par transfert réversible par addition fragmentation (RAFT) de l’acide acrylique, monomère dont la synthèse à partir de bioressources a été décrite et connait des développements industriels récents. Le couplage avec les molécules hydrophobes terpéniques a été effectué par estérification. Dans l’optique d’une chimie plus verte limitant l’utilisation de catalyseurs présentant une certaine toxicité mais également d’atteindre un meilleur contrôle de la composition du copolymère en groupements hydrophobes, une nouvelle génération de copolymères amphiphiles biosourcés a été synthétisée par copolymérisation radicalaire contrôlée par les nitroxydes (NMP) de l’acide acrylique avec un comonomère terpénique.Afin de comprendre le comportementde ces copolymères amphiphiles pH-sensibles en phase aqueuse, ces derniers ont été caractérisés par différentes méthodes (titration potentiométrique, mesure de tension de surface...).Ces copolymères amphiphiles biosourcés ont été utilisés comme stabilisants pour la synthèse de latex terpénique par polymérisation en émulsion ou en miniémulsion. Différents paramètres de synthèse ont été étudiés dans le but d’optimiser les conversions en monomère et les caractéristiques colloïdales des latex. La stabilisation des latex par des copolymères pH-sensibles confère cette propriété aux latex pour lesquels la floculation peut être déclenchée par une modification de pH.This thesis project aims to reduce the carbon footprint by using biomass products to synthesize different classes of biobased polymer materials, more precisely amphiphilic polymers as stabilizers for the synthesis of waterborne latex. Developing a new generation of biobased materials is at the heart of the project to support a circular economy. By valorizing the principles of green chemistry, the ultimate aim is to replace products derived fromfossil resources, whose production contributes to greenhouse gas emissions, with products derived from renewable biomass.The first part of this thesis aims to synthesize amphiphilic copolymers based on terpenes, a class of products derived from forest biomass, by coupling these hydrophobic molecules onto a hydrophilic polymer backbone of poly(acrylic acid). The latter was synthesized by reversible addition fragmentation transfer (RAFT) polymerization of acrylic acid, a monomer whose synthesis from bioresources was described and is undergoing recent industrial development. The coupling with hydrophobic terpene molecules was achieved by esterification. With a view to achieve greener chemistry by limiting the use of toxic catalysts but also to target a better control over copolymer composition in hydrophobic groups, a new generation of biobased amphiphilic copolymers was synthesized by nitroxide mediated radical copolymerization (NMP) of acrylic acid with a terpene comonomer. To understand the behavior of these pH-sensitive amphiphilic copolymers in aqueous media, they were characterized by various methods (potentiometric titration, surface tension measurement, etc.).These biobased amphiphilic copolymers were used as stabilizers for the synthesis of terpene-based waterborne latex via emulsion and miniemulsion polymerization. Various synthesis parameters were studied to optimize monomer conversions and latex colloidal features. The stabilization of latex particles by pH-sensitive copolymers conferred pH-responsiveness to latex for which flocculation can be triggered through a pH change
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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