1,720,958 research outputs found
Investigazioni teoriche di parametri di emissione dipendenti dalla temperatura in termometri molecolari a base di ioni lantanoidei
Get PDFIn questa tesi di dottorato, dedicata allo studio di sistemi molecolari luminescenti a base di ioni lantanoidei con applicazioni in termometria, sono state esplorate ed applicate tecniche di calcolo quantistico non routinarie al fine di determinare parametri e caratteristiche molecolari indispensabili per la comprensione dei meccanismi alla base della dipendenza dalla temperatura delle proprietà ottiche di luminescenza. Dopo una breve introduzione dedicata alla descrizione di questi sistemi, sono state descritte le basi teoriche necessarie per la comprensione delle simulazioni numeriche; successivamente, sono stati allegati alla tesi gli articoli scientifici pubblicati su riviste internazionali in cui sono stati riportati e discussi i risultati degli esperimenti numerici. Il tipo di modellizzazione adottato ha reso possibile non solo la razionalizzazione delle caratteristiche ottiche dei composti presi in considerazione, ma ha permesso la previsione del comportamento di sistemi molecolari non ancora caratterizzati.In this Ph.D. thesis, centred around the study of lanthanide-based luminescent mo-lecular systems with applications in thermometry, several high-level quantistic calculation techniques have been explored; these have been applied to determine parameters and molecular characteristics, which are useful for the comprehension of the underlying mechanisms defining the temperature dependence of the optical properties. After a brief introduction in which the general nature of the systems is discussed, theoretical bases of numerical simulations are illustrated; scientific articles published on international journals with peer review and describing the theoretical modeling results are also included. Theoretical tools obtained from these studies allow not only to rationalise the optical characteristics of the investigated systems, but also to predict the behaviour of systems which have not yet been char-acterised
Understanding Stabilization Factors in Heterodinuclear Ln–Al Complexes from DFT Simulations on Thermochemistry Data: A Counterintuitive Conclusion
No full textThis study validates a computational protocol to predict the stability of heterodinuclear complexes by varying ligands on both moieties and analyzing the reaction Gibbs free energy (Delta G (R)) values. To this purpose, a series of Eu-Al complexes with the general formula [Eu(L-Eu)(3)Al(L-Al)(3)], where L-Eu is the ligand of europium and L-Al is an oxygen donor ligand of aluminum, is used. The nature of the bridging bonds and thermochemical characteristics (Delta G (R), enthalpy, and entropy) of the complexes were evaluated via DFT calculations. We demonstrated that both entropic and enthalpic effects play a relevant role in the stability. The analysis of the series allows us to identify three Delta G (R) ranges where heterodinuclear complexes are (i) stable and easy to characterize, (ii) fragile and difficult to characterize, and (iii) not observed (unreacted precursors are recovered). To rationalize the trend of the stability and correlate it with the chemical nature of the ligands, we investigated the condensed Fukui function on the Al fragment. Results suggest that to obtain stable heteronuclear complexes, it is necessary to consider ligands with small condensed Fukui function values. This corresponds to a less nucleophilic oxygen site, yet counterintuitively, it allows the ligand to delocalize the received electronic charge and stabilize the complex
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
Theoretical investigation of temperature-dependent emission parameters in lanthanide-based luminescent molecular thermometers
No full textIn questa tesi di dottorato, dedicata allo studio di sistemi molecolari luminescenti a base di ioni lantanoidei con applicazioni in termometria, sono state esplorate ed applicate tecniche di calcolo quantistico non routinarie al fine di determinare parametri e caratteristiche molecolari indispensabili per la comprensione dei meccanismi alla base della dipendenza dalla temperatura delle proprietà ottiche di luminescenza. Dopo una breve introduzione dedicata alla descrizione di questi sistemi, sono state descritte le basi teoriche necessarie per la comprensione delle simulazioni numeriche; successivamente, sono stati allegati alla tesi gli articoli scientifici pubblicati su riviste internazionali in cui sono stati riportati e discussi i risultati degli esperimenti numerici. Il tipo di modellizzazione adottato ha reso possibile non solo la razionalizzazione delle caratteristiche ottiche dei composti presi in considerazione, ma ha permesso la previsione del comportamento di sistemi molecolari non ancora caratterizzati
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
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