1,720,959 research outputs found
Esplorando il potenziale sintetico degli arilchetoni fotoeccitati
Full text linkThe carbonyl system is one of the most prevalent functional groups in Nature. It is present in several classes of organic compounds that are essential for our daily life. Specifically, aryl ketones are a paradigmatic case of study in terms of photophysical and photochemical applications. Their use in synthetic photochemistry has been studied in detail during the 20th century. This thesis deals with the development of previously unexplored synthetic methods enabled by using new technologies. In particular, the utilization of microfluidic photoreactors enhanced the synthetic performance and scalability of several photochemical methods, e.g., Paternò–Büchi and photoenolization/Diels–Alder processes, while opening the way to unprecedented reactivity. Additionally, the careful mechanistic analysis of the occurring processes has been of pivotal importance during my PhD studies. Thus, the diastereoselectivity prediction for dearomative Paternò-Büchi reactions, the development of versatile organic photocatalysts and the investigation of challenging trifluoromethoxylation reactions have been studied on a rationale basis.The carbonyl system is one of the most prevalent functional groups in Nature. It is present in several classes of organic compounds that are essential for our daily life. Specifically, aryl ketones are a paradigmatic case of study in terms of photophysical and photochemical applications. Their use in synthetic photochemistry has been studied in detail during the 20th century. This thesis deals with the development of previously unexplored synthetic methods enabled by using new technologies. In particular, the utilization of microfluidic photoreactors enhanced the synthetic performance and scalability of several photochemical methods, e.g., Paternò–Büchi and photoenolization/Diels–Alder processes, while opening the way to unprecedented reactivity. Additionally, the careful mechanistic analysis of the occurring processes has been of pivotal importance during my PhD studies. Thus, the diastereoselectivity prediction for dearomative Paternò-Büchi reactions, the development of versatile organic photocatalysts and the investigation of challenging trifluoromethoxylation reactions have been studied on a rationale basis
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
Radical α-Trifluoromethoxylation of Ketones under Batch and Flow Conditions by Means of Organic Photoredox Catalysis
Full text linkThe first light-driven method for the α-trifluoromethoxylation of ketones is reported. Enol carbonates react with N-trifluoromethoxy-4-cyano-pyridinium, using the photoredox catalyst 4-CzIPN under 456 nm irradiation, affording the α-trifluoromethoxy ketones in ≤50% isolated yield and complete chemoselectivity. As shown by 29 examples, the reaction is general and proceeds very rapidly under batch (1 h) and flow conditions (2 min). Diverse product manipulations demonstrate the synthetic potential of the disclosed method in accessing elusive trifluoromethoxylated bioactive ingredients
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
Naphthochromenones: Organic Bimodal Photocatalysts Engaging in Both Oxidative and Reductive Quenching Processes
Full text linkTwelve naphthochromenone photocatalysts (PCs) were synthesized on gram scale.They absorb across theUV/Vis range and feature an extremely wide redox window (up to 3.22 eV) that is accessible using simple visible light irradiation sources (CFL or LED). Their excited-state redox potentials, PC*/PCC (up to 1.65 V) and PCC+/PC* (up to 1.77 V vs. SCE), are such that these novel PCs can engage in both oxidative and reductive quenching mechanisms with strong thermodynamic requirements. The potential of these bimodal PCs was benchmarked in synthetically relevant photocatalytic processes with extreme thermodynamic requirements. Their ability to efficiently catalyze mechanistically opposite oxidative/reductive photoreactions is a unique feature of these organic photocatalysts, thus representing a decisive advance towards generality, sustainability, and cost efficiency in photocatalysis
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
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