1,720,965 research outputs found
Future medicinal chemists experience flow chemistry: optimization by experimental design of the limiting synthetic step to the antifungal drug econazole nitrate
No full textA practical experience to showcase the potential of flow technology in the synthesis optimization of drugs has been developed and carried out by fourth year undergraduate students in Pharmaceutical Chemistry and Technology (CTF) at the University of Perugia. In particular, we present an experiment aimed at optimizing the monobromination reaction of 2′,4′-dichloroacetophenone, the limiting step to the synthesis of the antifungal drug econazole nitrate. Throughout the experiment, the students learn how to integrate flow chemistry and experimental design to expedite experimental screening and reaction optimization. Moreover, the students have the possibility to exploit the use of automation to improve data generation and reduce human intervention in repetitive, expensive or hazardous experiments
Multicomponent and Metal-Free Diels–Alder/Aromatization Approach to the Stereospecific Synthesis of E-(Hetero)Stilbenes and Diarylacetylenes
No full textHerein, we present a novel and metal-free approach to the stereospecific synthesis of E-stilbenes. Starting from substituted 6-arylhexa-3,5-dien-2-ones, a multicomponent enolacetylation/intermolecular Diels-Alder reaction was performed using ethyl acetate as a green solvent. The obtained cycloadducts were then oxidized without purification to produce the stilbenic products in good yields (up to 67%) and with complete (E)-stereospecificity and regioselectivity. Moreover, heterostilbenes were synthetized using this approach, displaying the potential applications of this protocol in pharmaceutical and material sciences. The proposed methodology was further extended to the synthesis of diarylacetylenes, furnishing a new metal-free synthetic access to this important class of compounds. Furthermore, DFT calculations were performed confirming a concerted [4+2] reaction mechanism of the key ring-forming step. At last, the energetic analysis of the possible Transition States helps to shed some light on the experimentally observed total regio- and chemoselectivit
The Medicinal Chemistry in the Era of Machines and Automation: Recent Advances in Continuous Flow Technology
Full text linkMedicinal chemistry plays a fundamental and underlying role in chemical biology, pharmacology, and medicine to discover safe and efficacious drugs. Small molecule medicinal chemistry relies on iterative learning cycles composed of compound design, synthesis, testing, and data analysis to provide new chemical probes and lead compounds for novel and druggable targets. Using traditional approaches, the time from hypothesis to obtaining the results can be protracted, thus limiting the number of compounds that can be advanced into clinical studies. This challenge can be tackled with the recourse of enabling technologies that are showing great potential in improving the drug discovery process. In this Perspective, we highlight recent developments toward innovative medicinal chemistry strategies based on continuous flow systems coupled with automation and bioassays. After a discussion of the aims and concepts, we describe equipment and representative examples of automated flow systems and end-to-end prototypes realized to expedite medicinal chemistry discovery cycles
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
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