1,720,954 research outputs found
ARCHITECTED MATERIALS FOR FUNCTIONAL PROPERTIES
No full textQuesta tesi analizza l'influenza della morfologia dei nanomateriali e dell'ingegneria interfacciale sulla dinamica del trasferimento di carica in sistemi eterostrutturati. Lo studio inizia con una valutazione sistematica di nanoparticelle di TiO2 e di array di nanotubi di TiO2 (TNTAs), rivelando che i TNTAs in fase anatase con un'altezza ottimizzata di 8 μm mostrano un'attività superiore nella reazione di evoluzione dell'idrogeno (HER), grazie a percorsi di trasporto di carica migliorati e a proprietà elettroniche favorevoli. Successivamente, è stato esplorato il ruolo della chimica superficiale nel controllo del trasferimento di carica interfacciale utilizzando nanocristalli di perovskite CsPbBr3 (PNCs) con lunghezze di catena dei leganti controllate. I leganti a catena corta hanno facilitato un trasferimento elettronico più efficiente verso le nanostrutture di TiO2, con gli array di nanotubi che hanno superato le pellicole di nanoparticelle nelle configurazioni allo stato solido. Le perovskiti drogati con Mn hanno ulteriormente evidenziato il comportamento di quenching dipendente dalla morfologia del TiO2, sebbene approfondimenti più dettagliati sulla dinamica dei portatori di carica richiedano tecniche spettroscopiche avanzate. Infine, i quantum dots core–shell CdTe/CdSe sono stati interfaccati con morfologie di TiO2, rivelando comportamenti contrastanti tra le fasi in soluzione e in film sottile. In soluzione, le nanoparticelle di TiO2 hanno promosso un quenching più marcato, mentre nei film sottili, i TNTAs hanno consentito un'estrazione di carica più efficiente e un trasporto direzionale, portando a una degradazione fotocatalitica efficace del colorante Rhodamine B in soluzione acquosa. Complessivamente, questo lavoro dimostra che l'ottimizzazione della morfologia, della fase e della chimica superficiale dei nanomateriali è fondamentale per migliorare i processi di trasferimento di carica e l'attività fotocatalitica. Le conoscenze acquisite offrono una strada per la progettazione di nanostrutture ibride ad alte prestazioni per la generazione fotocatalitica di idrogeno e per applicazioni optoelettroniche correlate.This thesis investigates the influence of nanomaterial morphology and interfacial engineering on charge transfer dynamics in a heterostructure system. The study begins with a systematic evaluation of TiO2 nanoparticles and nanotube arrays (TNTAs), revealing that anatase-phase TNTAs with an optimized height of 8 μm exhibit superior hydrogen evolution reaction (HER) activity, driven by enhanced charge transport pathways and suitable morphology. Subsequently, the role of surface chemistry in governing interfacial charge transfer was explored using CsPbBr3 perovskite nanocrystals (PNCs) with controlled ligand chain lengths. Short-chain ligands facilitated more effective electron transfer to TiO2 nanostructures, with nanotube arrays outperforming nanoparticle films in solid-state configurations. Mn-doped perovskites further highlighted the morphology-dependent quenching behaviour of TiO2, though deeper insights into charge carrier dynamics require advanced spectroscopic techniques. Finally, CdTe/CdSe core–shell quantum dots were interfaced with TiO2 morphologies, revealing contrasting behaviours between solution and thin-film phases. In solution, TiO2 nanoparticles promoted stronger quenching, while in thin films, TNTAs enabled more efficient charge extraction and directional transport leading to efficient photocatalytic degradation of aqueous Rhodamine B dye. Collectively, this work demonstrates that fine-tuning nanomaterial morphology, phase, and surface chemistry is critical to optimizing charge transfer processes and photocatalytic activity. The insights gained may provide a pathway for designing high-performance, hybrid nanostructures for photocatalysis and other optoelectronic applications
Tailoring Charge Donor–Acceptor Interaction in CsPbBr3 Perovskite Nanocrystals through Ligand Exchange
Get PDFThe surface ligands in colloidal metal halide perovskites influence not only their intrinsic optoelectronic properties but also their interaction with other materials and molecules. Donor–acceptor interactions of CsPbBr3 perovskite nanocrystals with TiO2 nanoparticles and nanotubes are explored by replacing long‐chain oleylamine ligands with short‐chain butylamines. Through postsynthesis ligand exchange, the nanocrystals are functionalized with butylamine ligands while their intrinsic properties are maintained. In solution, butylamine‐capped nanocrystals exhibit reduced photoluminescence intensity with increasing TiO2 concentration but without any change in photoluminescence lifetime. Intriguingly, the Stern–Volmer plot depicts different slopes at low and high TiO2 concentrations, suggesting donor‐acceptor interaction through mixed static photoluminescence quenching and quenching sphere of action mechanism . Oleylamine‐capped nanocrystals in solution, on the other hand, show no interaction with TiO2, as indicated by consistent photoluminescence intensities and lifetimes before and after TiO2 addition. In films, both types exhibit decreased photoluminescence lifetime with TiO2, indicating enhanced donor–acceptor interaction, which is discussed in terms of electron transfer. TiO2 nanotubes enhance nonradiative recombination more in butylamine‐capped CsPbBr3 perovskite nanocrystals, emphasizing the role of ligand chain length
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
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