1,720,960 research outputs found
Sintesi e caratterizzazione di nuovi materiali nanostrutturati per sensori amperometrici
No full textI (bio)sensori elettrochimici sono spesso considerati una valida alternativa agli strumenti di analisi ingombranti, costosi e complessi utilizzati in laboratorio, in quanto possono fornire risultati affidabili con tempi e costi inferiori. Recentemente, i (bio)sensori indossabili hanno ricevuto un crescente interesse da parte delle comunità scientifiche e mediche, poiché sono dei dispositivi non invasivi ed economici per monitorare, anche a distanza, parametri di primaria importanza per la salute o il benessere fisico attraverso l'analisi dei fluidi umani (sudore, saliva, lacrime e liquido interstiziale). Spesso viene preferito il sudore, poiché consente il monitoraggio non invasivo e simultaneo di molti parametri, ad esempio elettroliti, glucosio, lattato ed etanolo. La selettività verso un particolare analita è data da specifici elementi di bioriconoscimento, che dovrebbero essere stabilmente ancorati sulla superficie dell'elettrodo impiegato. Il grafene e i suoi derivati (GRM) sono stati largamente impiegati per la realizzazione di dispositivi elettrochimici, poiché possiedono dimensioni nanometriche e gruppi funzionali ossidati che possono essere sfruttati per ottenere una funzionalizzazione covalente del nanomateriale con specifici (bio)recettori, oltre che per attivare effetti elettrocatalitici verso diverse specie, ad esempio la nicotinammide adenina dinucleotide (NADH), un cofattore di numerosi enzimi.
In questa tesi di dottorato ho focalizzato le attività di ricerca sullo sviluppo di nuove piattaforme elettrodiche a base di grafene per la rilevazione di analiti di primaria importanza per la salute e il benessere fisico. La rilevazione simultanea di glucosio e lattato in un flusso continuo di una matrice complessa simile al sudore umano è ottenuta su biosensori costruiti con un ossido di grafene (GO) legato covalentemente al chitosano; la robustezza e l’applicabilità dei sistemi di rilevazione ottenuti sono state testate in condizioni molto vicine all’effettiva applicazione del dispositivo finale sulla pelle. I vantaggi dovuti a questo ancoraggio stabile dei biorecettori sono stati poi confermati dalla realizzazione di un nuovo genosensore per il rilevamento selettivo di virus, sviluppato dopo aver scelto il GO funzionalizzato con polietilenimmina per appaiare una sequenza di DNA complementare ad uno specifico target di RNA virale. Inoltre, gli effetti stabilizzanti indotti dal legame covalente dei biorecettori, ottenuto dall'intermediazione di chitosano o polietilenimmina, sono stati determinati quantificando gli elementi di bioriconoscimento ancorati su GO tal quale e modificato. Nella seconda parte del lavoro, ho focalizzato le attività di ricerca sullo sviluppo di nuove piattaforme elettrodiche che sono allo stesso tempo il trasduttore e l'elemento sensibile, per la realizzazione di dispositivi pronti all'uso altamente fattibili in applicazioni on-site. In un primo approccio, sono stati ottenuti degli inchiostri bioreattivi e stampabili con inkjet dopo aver ancorato stabilmente i biorecettori su fogli di grafene che espongono gruppi carbossilici; questi inchiostri sono stati stampati su elettrodi commerciali o realizzati appositamente e i biosensori così ottenuti sono subito pronti per la rilevazione dell'analita target. In un secondo approccio, invece, sono state ottenute piattaforme di elettrodi su supporti tessili e plastici flessibili utilizzando graphene paper, un GRM conduttivo simile alla carta; grazie a specifiche funzionalità contenenti ossigeno presenti sulla superficie, questi elettrodi attivano l'elettrocatalisi verso l'ossidazione del NADH senza un’ulteriore funzionalizzazione, superando i dispositivi commerciali e aprendo nuove possibilità di impiego ai dispositivi indossabili.Electrochemical (bio)sensors are often considered a viable alternative to the bulky, expensive, and complex analytical instruments used in the laboratory, as they can provide reliable results at lower times and costs. Recently, wearable (bio)sensors have received growing consideration from scientific and medical communities, since they constitute non-invasive and cheap devices to monitor, also by remote, parameters of primary importance for human health or fitness goals from the analysis of human fluids (sweat, saliva, tears, and interstitial fluid). Human sweat is often preferred, since it enables non-invasive monitoring of many parameters at the same time, e.g. electrolytes, glucose, lactate, ethanol. Selectivity towards a particular biomarker is given by specific biorecognition elements which should be stably anchored on the surface of the employed electrode. Graphene and its related materials (GRM) have been largely employed for the realization of electrochemical devices, since they possess nanosized dimensions and oxidized functional groups that can be exploited to achieve covalent functionalization of the nanomaterial with defined (bio)receptors and to activate electrocatalytic effects towards several species, e.g. nicotinamide adenine dinucleotide (NADH), a cofactor of several enzymes.
In this PhD Thesis, I focused the research activities on the development of novel graphene-based electrode platforms for the detection of biomarkers of primary importance for health and fitness goals. Simultaneous detection of glucose and lactate directly in a continuous flow of a complex matrix resembling human sweat is achieved on biosensors obtained with a graphene oxide (GO) covalently linked to chitosan; the robustness and the feasibility of the obtained detection systems was tested in conditions simulating the actual application of a final device on the skin. The advantages lying in the stable anchoring of the bioreceptors were also confirmed by the realization of a new genosensor for the selective detection of viruses, developed after choosing polyethylenimine-functionalized GO to anchor a nucleic acid sequence complementary to a specific viral RNA target. Moreover, the stabilizing effects induced by the covalent bonding of the bioreceptors, achieved by the intermediation of either chitosan or polyethyleneimine, was unravelled by the quantification of the amount of anchored biorecognition elements on pristine and on modified GO. In the second part of the work, I focused the research activities on the development of novel electrode platforms constituting at the same time the transducer and the sensing element for the realization of ready-to-use devices highly feasible in on-site applications. In a first approach, bioresponsive inkjet printable inks were obtained after stably anchoring the bioreceptors on graphene foils exposing carboxylic groups; after printing these inks on commercial or home-made electrodes, the so-obtained biosensors are ready to be employed for the detection of the target analyte. As a second approach, electrode platforms on flexible plastic and textile supports were obtained employing graphene paper, a conductive paper-like GRM; thanks to specific oxygen-containing moieties on the surface, these electrodes activate electrocatalysis towards NADH oxidation without any further functionalization step, outperforming commercial devices and opening new possibilities in wearable devices
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
- …
