1,720,957 research outputs found
soluzioni organiche di sintesi o di estrazione naturale per l'energy storage
No full textThe following thesis, developed in collaboration with the industrial partner Bettery S.r.l., falls within the framework of bio-based and synthetic materials for energy storage. It addresses two main topics:
1. The development of redox-active organic species with an open-shell electronic configuration for use as redox mediators in Li-O2 semisolid redox flow batteries.
2. The development of sustainable biorefining processes capable of producing carbonaceous materials with potential applications in energy storage devices.
In Chapter I, the main energy storage devices are presented, along with a critical analysis of their key advantages and disadvantages. Among these, Li-O2 technology emerges as one of the most promising solutions in terms of energy and power density for replacing traditional fossil fuels. However, Li-O2 batteries still suffer from several challenges, primarily the high overpotentials during charge and discharge processes. One possible solution to this issue is the use of organic redox mediators (ORMs).
In Chapter II, the main families of ORMs are discussed, with a focus on species having an open-shell electronic configuration, i.e., inert organic free radicals. Additionally, examples of bifunctional ORMs, suitable for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), are presented. Among the open-shell redox mediators, the tris(2,4,6-trichlorophenyl)methyl radical (TTM) was selected as an inspiration for the design of new polybrominated and polyfluorinated trityl radical cores. Two new polyhalogenated trityl radicals were designed, synthesized, and characterized as molecular building blocks for the development of novel bifunctional trityl redox mediators.
In Chapter III, TTM-like singlet diradicaloids were tested, for the first time, as a new class of ORMs. A definition of “singlet diradicaloid” is provided, and the main advantages and drawbacks of diradicaloids compared to free radicals are discussed. Among these, the recently reported TTM-like Thiele hydrocarbon (TTH) and TTM-like Chichibabin hydrocarbon (TTM-TTM) exhibit promising potential for the ORR in Li-O2 batteries. The electrochemical performance of TTH in a carbonaceous Li-O2 semisolid redox flow cell exceeds that of TTM, used as a benchmark, by a factor of four. Consequently, the TTH core was coupled via nucleophilic aromatic substitution with piperidine to develop a new bifunctional diradicaloid, named PTTH. This new molecule was fully characterized and tested in Bettery S.r.l.'s electrochemical setup, where it retained its catalytic effect on the ORR and doubled the performance of the TEMPO radical (used as a benchmark) in the OER. Finally, a new and more efficient synthetic route for the preparation of TTM-TTM was introduced, opening new perspectives in the design of bifunctional ORMs based on this diradicaloid.
In Chapter IV, an ethanosolv process for the lignin fractionation was investigated, aiming to obtain a biopolymer embedded with electroactive sites. This material holds promise as a substitute for fossil carbon in carbonaceous Li-O2 semisolid redox flow batteries or supercapacitors. An overview of lignin extraction methods is provided, highlighting the advantages of lignin-first approaches, which help preserve the biopolymer native structure. Lignin was extracted from agricultural wastes, such as walnut, almond, and pistachio shells, focusing on the effects of ball milling pretreatment and microwave irradiation on the extracted lignin structure and yield. Interestingly, a novel electroactive lignin-based biopolymer was obtained through a one-step extraction-phenolization through an esterification between the redox-active gallic acid and the aliphatic OH groups of lignin. This new material was fully characterized both structurally and electrochemically. The proposed extraction process opens new perspectives for the functionalization of lignin with electroactive molecules.La seguente tesi, sviluppata in collaborazione con il partner industriale Bettery S.r.l., è incentrata sullo sviluppo di materiali bio-based e sintetici per l'accumulo di energia. Essa affronta due principali tematiche:
1. Lo sviluppo di molecole organiche redox-attive con una configurazione elettronica open-shells utilizzabili come mediatori redox nelle batterie Li-O2 semisolide a flusso.
2. Lo sviluppo di processi sostenibili in grado di produrre materiali carboniosi con potenziali applicazioni nei dispositivi di accumulo di energia.
Nel Capitolo I vengono presentati i principali dispositivi di accumulo di energia, accompagnati da un'analisi critica dei loro principali vantaggi e svantaggi. Tra questi, la tecnologia Li-O2 emerge come una delle soluzioni più promettenti in termini di densità di energia e potenza per sostituire i combustibili fossili tradizionali. Tuttavia, le batterie Li-O2 soffrono ancora di diverse problematiche, fra cui le alte sovratensioni durante i processi di carica e scarica. Una possibile soluzione a questo problema è l'uso di mediatori redox organici (ORMs).
Nel Capitolo II vengono discusse le principali famiglie di ORMs, con un focus sulle specie con una configurazione elettronica open-shells, ossia i radicali organici inerti. Inoltre, vengono presentati esempi di ORMs bifunzionali, adatti sia per la reazione di riduzione dell'ossigeno (ORR) che per la reazione di evoluzione dell'ossigeno (OER). Tra i mediatori redox open-shells, il tris(2,4,6-triclorofenil)metil radicale (TTM) è stato selezionato come molecola modello per il design di nuovi nuclei radicalici polibromurati e polifluorurati. Sono stati progettati, sintetizzati e caratterizzati due nuovi radicali tritilici polialogenati come precursori per lo sviluppo di nuovi mediatori redox bifunzionali.
Nel Capitolo III, sono stati testati per la prima volta i diradicaloidi di singoletto derivanti dal TTM, come nuova classe di ORMs. In questo capitolo viene fornita una definizione di "diradicaloide di singoletto" e vengono discussi i principali vantaggi e svantaggi dei diradicaloidi rispetto ai monoradicali. Tra questi, l'idrocarburo di Thiele derivante dal TTM (TTH) e l'idrocarburo Chichibabin derivante dal TTM (TTM-TTM) mostrano un potenziale redox promettente per la ORR nelle batterie Li-O2. Le prestazioni elettrochimiche del TTH in una cella Li-O2 semisolida a flusso superano di quattro volte quelle del TTM, utilizzato come molecola modello. Di conseguenza, il nucleo TTH è stato accoppiato tramite sostituzione nucleofila aromatica con la piperidina per sviluppare un nuovo diradicaloide bifunzionale, chiamato PTTH. Questa nuova molecola è stata completamente caratterizzata e testata nell'impianto elettrochimico di Bettery S.r.l., dove ha mantenuto il suo effetto catalitico sulla ORR e raddoppiando le prestazioni del radicale TEMPO (utilizzato come molecola modello) nell'OER. Infine, è stato utilizzato un nuovo metodo di sintesi più efficiente per la preparazione del TTM-TTM, aprendo nuove prospettive nel design di ORMs bifunzionali basati su questo diradicaloide.
Nel Capitolo IV, è stato studiato un processo ethanosolv per il frazionamento della lignina, con l'obiettivo di ottenere un biopolimero elettroattivo. Questo materiale ha un grande potenziale come alternativa al carbon fossile nelle batterie Li-O2 semisolide a flusso o nei supercapacitori. In questo capitolo viene fornita una panoramica dei metodi di estrazione della lignina, evidenziando i vantaggi degli approcci lignin-first, che aiutano a preservare la struttura nativa del biopolimero. La lignina è stata estratta da scarti agroindustriali, come gusci di noce, mandorla e pistacchio, concentrandosi sugli effetti del pretrattamento tramite ball milling e dell'irradiazione a microonde sulla struttura e sulla resa della lignina estratta
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
- …
