1,720,979 research outputs found
Dramatically Enhanced Reactivity of Fullerenes and Tetrazine towards the Inverse-Electron-Demand Diels-Alder Reaction inside a Porous Porphyrinic Cage
No full textInverse-electron-demand Diels-Alder reaction (IEDDA) between fullerenes and 1,2,4,5-tetrazine generally requires harsh conditions and long reaction times due to their strong electron-accepting nature. Herein, we report a dramatic enhancement in the reactivity of the fullerenes (C-60/C-70)-tetrazine reaction inside a porous Zn-porphyrinic cage (Zn-PB) under sustainable conditions by installing a tetrazine-based axle (LA) via metal-ligand coordination bond, which modulates the cavity size to facilitate the encapsulation of fullerenes. Upon encapsulation, the close proximity of fullerenes and the tetrazine group of LA dramatically increase their reactivity towards the IEDDA reaction to form fullerene-tetrazine adducts. Furthermore, the C-60-tetrazine adduct is rearranged upon hydration to a bent-shaped C-60-pyrazoline adduct that can be released from the Zn-PB cavity in the presence of excess LA, thus catalyzing the formation of C-60-pyrazoline adduct inside Zn-PB without product inhibition.11Nsciescopu
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
Remotely controllable supramolecular rotor mounted inside a porphyrinic cage
No full text© 2021 Elsevier Inc.The confinement of molecular machines into nanostructured cages and controlling their functions by external stimuli holds great potential for the creation of smart functional materials that imitate the embodied intelligence of biological processes. Herein, we report the construction of a supramolecular rotor in a porous Zn-metallated porphyrinic cage (1) by encapsulation of a tetrazine-based linear axle (LA) via metal-ligand coordination bond, followed by post-assembly modification to append a controllable side arm to LA via inverse electron demand Diels-Alder (IEDDA) reaction. While the rotor alone shows nearly no motion, the addition of pyridine derivatives as a zinc coordinating ligand results in both 90° jump-like rotary motion of the rotor and slow tumbling motion of the rotor axle in a stochastic manner. Interestingly, the dual motions of the rotor can be reversibly controlled by the UV and visible light-induced coordination and dissociation of an azopyridine-based ligand with Zn centers as a signal transducer.11Nsciescopu
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
Recursive Anion-Triggered Tandem Reactions of ortho-Bis-ynones: Tunable Synthesis of 1Indenones and Cyclopenta[a]inden-8(2H)ones
No full textRecursive anion-mediated activation
of o-bis-ynones
sets off a Michael addition–aldol reaction–dehydrative
rearrangement cascade, leading to the one-pot synthesis of 1-indenones
via orthogonal interplay between the two ortho-ynone
moieties. Repeating the recursive anion engagement with the 1-indenones
unfolded access to a functionally embellished cyclopenta[a]inden-8(2H)-one core and its spiroannulated analogues
either directly or stepwise through tandem 1,6-Michael-type addition–6π
electrocyclization and an in situ oxidation sequence
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