1,721,295 research outputs found
Pioneering Metal-Free Late-Stage C−H Functionalization Using Acridinium Salt Photocatalysis
No full textUsing organic dyes as photocatalysts is an innovative approach to photocatalytic organic transformations. These dyes offer advantages such as widespread availability, adaptable absorption properties, and diverse chemical structures. Recent progress has led to the development of organic photocatalysts that can utilize visible light to modify chemically inert C−H bonds. These catalysts are sustainable, selective, and versatile, enabling mild reactions, late-stage functionalization, and various transformations in line with green chemistry principles. As catalysts in photoredox chemistry, they contribute to the development of efficient and environmentally friendly synthetic pathways. Acridinium-based organic photocatalysts have proved valuable in late-stage C−H functionalization, enabling transformative reactions under mild conditions. This review emphasizes their innovative features, such as organic frameworks, efficient light absorption properties, and their applications in modifying complex molecules. It provides an overview of recent advancements in the use of acridinium-based organic photocatalysts for late-stage C−H bond functionalization without the need for transition metals, showcasing their potential to expedite the development of new molecules and igniting excitement about the prospects of this research in the field
An Efficient Strategy for Quinazolinone and Benzimidazole Synthesis Using Microwave-Assisted Copper-Catalyzed Aerobic Oxidation of Amines
Full text linkMicrowave-assisted organic synthesis (MAOS) has emerged as an effective technique for accelerating chemical reactions while enhancing efficiency and selectivity. In this study, we developed a copper-catalyzed method for aerobic oxidative coupling to synthesize quinazolinones and benzimidazoles, using oxone as the oxidant under microwave irradiation. This method successfully couples amines with various partners, including 2-aminobenzamides and o-phenylenediamines. The strategy demonstrates broad substrate compatibility, exhibits good functional group tolerance, and consistently achieves moderate yields, making it a versatile and efficient approach for synthesizing heterocycles
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
Oxidized thiourea derivatives: uncovering new frontiers with resonant acoustic mixing (RAM)
No full textNitrogen-containing compounds are essential for producing active pharmaceutical ingredients. However, traditional synthesis methods for these compounds often involve environmentally harmful practices, such as high temperatures, long reaction times, and using toxic reagents and large amounts of solvents. Recently, solvent-free techniques have gained attention as effective and more sustainable alternatives. A significant advancement in this field is resonance acoustic mixing (RAM), a technology that enhances the reactivity of the reaction components without the need for grinding media. RAM operates through vertical oscillations at a constant frequency of 60 Hz, with the G factor adjustable up to 100G. This study investigates the reactivity of thiourea trioxide (TTO), an oxidized thiourea derivative, for preparing 2-amino benzoxazoles. This process efficiently yields the desired aza-heterocycles, with the products easily recovered by simple filtration of the crude reaction mixture. This research highlights the potential of RAM and mechanochemistry to create a more sustainable and efficient synthetic pathway for nitrogen-containing pharmaceutical compounds, promoting greener chemistry practices. Additionally, we evaluated the reactivity of another oxidized derivative of thiourea, thiourea dioxide (TDO), allowing for a comparison between these two compounds
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
- …
