1,720,958 research outputs found
MATERIALI ELETTRODICI ED ELETTROLITICI PER LO SVILUPPO DI BATTERIE SECONDARIE A BASE DI IONI ALCALINI E ALCALINI-TERROSI
No full textLe politiche di energia verde stanno aumentando l'attenzione della ricerca sullo sviluppo di batterie secondarie post-ioni di litio. Queste tecnologie devono soddisfare alcuni requisiti: (i) un'elevata densità energetica; (ii) un'elevata scalabilità industriale; e (iii) lo sfruttamento di materie prime a basso costo e ad alta disponibilità. Per raggiungere questi obiettivi, le attività di ricerca svolte in questo progetto di dottorato sono state focalizzate sullo sviluppo e lo studio di materiali elettrolitici ed elettrodici per batterie secondarie alcaline (Li+, Na+) e alcalino-terrose (Mg2+, Ca2+). In questo progetto, gli sforzi sono stati dedicati allo studio di varie classi di materiali elettrolitici per batterie secondarie a stato solido. Un elettrolita ceramico (NaFT) è stato sintetizzato con una reazione in stato solido ed è costituito da nanoparticelle core-shell il cui core è TiO2 circondato da una shell fluorurata e sodiata. L'ottimizzazione della sintesi permette di raggiungere una conducibilità ionica a 25°C di 3.89∙10-4 S·cm-1. Viene inoltre dimostrata l'attività elettrochimica nei processi di deposizione/stripping di Na+. Un approccio per migliorare la conduttività ionica a 25°C e per ridurre la resistenza di carica all’interfaccia è quello drogando il NaFT ceramico con un liquido ionico (IL, EMImTFSI). Lo studio rivela una microstruttura dell'elettrolita che presenta: (i) un equilibrio di scambio cationico; (ii) una matrice dinamica dell’IL interposta tra le nanoparticelle; e (iii) lo sfruttamento di percorsi di conduzione multipli per la migrazione dei portatori di carica a lungo raggio. Questa nuova microstruttura mostra un'elevata conduttività ionica a 25°C (8.5∙10-4 S cm-1) e una buona densità di corrente durante l'elettrodeposizione e lo stripping del Na+. Un'altra strategia per ottenere un elettrolita a conduzione ionica allo stato solido è lo sviluppo di una rete polimerica tridimensionale i cui modi segmentali delle catene polimeriche assistono alla migrazione al lungo raggio della carica. Un primo esempio è la preparazione di un elettrolita ibrido organico-inorganico per batterie secondarie al sodio ((Na-HION)n/PEGDME). Questo elettrolita è costituita da una rete polimerica tridimensionale, in cui le catene di poli(ossietilene) (POE) fungono da ponti tra gli atomi di Zr(IV) ed è drogata NaClO4. Il drogaggio con un agente plastificante, il poli(ossietilene) dimetiletere (PEGDME 250), permette di favorire la dinamica del sistema, favorendo così la conducibilità dello ione Na+. Il secondo studio verte sulla sintesi di elettroliti polimerici solidi a base di POE drogati con CaTf2 (PC400/CaTf2 e PC1000/CaTf2). Questi materiali vengono studiati in funzione del peso molecolare della matrice polimerica mediante la spettroscopia elettrica a banda larga (BES). Viene riportato lo sviluppo di elettroliti IL basati su Sn e Mg. L'IL proposto è ottenuto dalla reazione di 1-butil-1-metilpirrolidinio cloruro (Pyr14Cl) con (CH3)2SnCl2 e δ-MgCl2. Questi composti sono accuratamente scelti per favorire la formazione di complessi anionici estesi a base di Sn e Cl. Questi complessi sono responsabili dell'elevata conduttività ionica a 25°C e dei processi elettrochimici di deposizione/stripping di Mg2+ con una buona densità di corrente e basso sovrapotenziale. Questi parametri rendono gli IL proposti dei buoni candidati come elettroliti per la batteria secondaria al magnesio. Tutti questi elettroliti sono studiati per chiarire l'interazione tra le proprietà strutturali e il meccanismo di conduzione. Infine, l'attenzione è posta sull'influenza dell'inserimento di metalli di transizione non tossici (Fe, Ni, e Mn) sulle prestazioni elettrochimiche di un materiale catodico tipo olivina per batterie secondarie al sodio e al litio. Questo progetto di dottorato mira a contribuire allo sviluppo di materiali per la prossima generazione di batterie secondarie post-ioni di litio a stato solidoThe green energy policies are currently boosting the attention of academic research on the development of post-lithium-ion secondary batteries. These technologies must satisfy some requirements: (i) a high-energy density; (ii) a high industrial scalability; and (iii) the exploitation of low cost and high available raw materials. In order to reach these goals, the research activities carried out in this PhD project are focused on the development and study of electrolyte and electrode materials for alkali (Li+, Na+), and alkaline-earth (Mg2+, Ca2+) secondary batteries. In this PhD project, major efforts are devoted on the study of various classes of electrolyte materials for all-solid state secondary batteries. A ceramic electrolyte (NaFT) is synthetized by a solid-state reaction and consists of core-shell nanoparticles whose core is TiO2 surrounded by a sodiated fluorinated shell. The optimization of the synthesis allows to reach a room-temperature ion conductivity of 3.89∙10-4 S·cm-1. The electrochemical activity in the Na+ deposition/stripping processes are also demonstrated. An approach to enhance the RT ion conductivity, and to reduce the interfacial charge resistance, is obtained by doping of the ceramic NaFT with an ionic liquid (IL, EMImTFSI). The study reveals a microstructure of the composite electrolyte that feature: (i) a cation exchange equilibrium; (ii) an IL dynamic matrix interposed between the nanoparticles; and (iii) the exploitation of multiple conduction pathways for the long-range charge carrier migration. This new microstructure shows a high RT ion conductivity (8.5∙10-4 S cm-1) and a good current density during the Na+ electrodeposition and stripping. Another strategy to obtain a high performing solid state ion conducting electrolyte is the development of a three-dimensional polymer network whose segmental motions of polymer chains are assisting the long-range charge migration. A first example is the preparation of a hybrid organic-inorganic electrolyte for sodium secondary batteries ((Na-HION)n/PEGDME). This electrolyte consists of a three-dimensional polymer network where the poly(oxyethylene) (POE) chains act as bridges between the Zr(IV) atoms, and it is doped with NaClO4 salt. The doping with a plasticizing agent, poly(oxyethylene) dimethylether (PEGDME 250), allows to promote the dynamics of the system, and thus promoting the Na+ ion conductivity. The second study focuses on the synthesis of POE-based solid polymer electrolytes doped with CaTf2 salt (i.e., PC400/CaTf2 and PC1000/CaTf2). These materials are investigated as a function of the molecular weight of the polymer matrix by means of broadband electrical spectroscopy (BES). The development of Sn and Mg-based IL electrolytes is reported. The proposed IL is obtained by the reaction of 1-butyl-1-methylpyrrolidinium chloride (Pyr14Cl) with (CH3)2SnCl2 and δ-MgCl2. These compounds are accurately chosen to promote the formation of extended anionic tin- and chloride-based complexes. These complexes are responsible for the high RT ion conductivity, and the electrochemical Mg2+ deposition/stripping processes with good current density and low overpotential. These parameters make the proposed ILs a good candidate as electrolytes for the magnesium secondary battery. All these electrolytes are studied in order to clarify the interplay between the structural properties and the investigated conductivity mechanism. In the last part of this PhD project, the attention is posed on the influence of the insertion of non-toxic transition metals (Fe, Ni, e Mn) on the electrochemical performance of an olivine-like cathode material for sodium and lithium secondary batteries. Taking all together, this PhD project aims to contribute to the development of novel materials for the next generation of all-solid-state post-lithium-ion secondary batteries
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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