1,720,994 research outputs found
Turning lipophilic phthalocyanines/TiO2 composites into efficient photocatalysts for the conversion of CO2 into formic acid under UV–vis light irradiation
No full textMetal-free, Cu(II)- or Zn(II) tetrakis [4-(2,4-bis-(1,1-dimethylpropyl)phenoxy)]phthalocyanines loaded
over TiO2 (anatase) proved to be active in the photoreduction of CO2 to formic acid (HCO2H) in water under
UV–vis light. CuPc/TiO2 is catalyst of choice, allowing to reach a maximum yield of HCO2H, unequalled
by any other similar catalytic systems. Because of their low environmental impact, low potential cost,
and efficient power conversion, these multipurpose materials show promise in the setup of sustainable
methods for CO2 valorization
Oxidation-proof microemulsions: Microstructure and reactivity in the presence of dioxiranes
Full text linkDioxiranes are used as reagents in a myriad of synthetically useful oxidations performed in aqueous medium.
To extend such an approach also to substrates that are highly hydrophobic, we propose here the use
of microemulsions based on the surfactant hexadecyltrimethylammonium hydrogen sulphate (CTAHS)
because of its high stability against peroxide species. In this paper, we examine the dioxirane (isolated
or generated in situ) reactivity in different CTAHS microemulsions. Yield and selectivity of the oxidation
of b-methylstyrene by dimethyldioxirane (DDO) generate ‘‘in situ’’ and of laurolactam by isolated
methyl(trifluorometyl)dioxirane (TFDO) were studied. For each microemulsion, the aggregate size and
the localization of the components were determined by a combination of NMR and light scattering techniques.
The hydrodynamic radius of the micelles is close to the length of the surfactant and this suggests
they are spherical in shape. When acetone (the precursor of DDO) is present in the formulation, it partitions
itself between the aqueous bulk and the micellar palisade so that the dioxirane eventually formed is
readily available to oxidize substrates secluded in the micelle. Apolar substrates, confined within the
micelles, are protected from uncontrolled oxidations, leading to an astonishing high selectivity of oxidation
of laurolactam to 12-nitro-lauric acid by TFDO. This opens the way to an easy procedure (performed
in water under mild conditions) to synthetize x-nitroacids
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
Selective Synthesis of Hydroxy Analogues of Valinomycin using Dioxiranes
No full textA synthesis of representative monohydroxy derivatives of valinomycin (VLM) was achieved under mild conditions by direct hydroxylation at the side chains of the macrocyclic substrate using dioxiranes. Results demonstrate that the powerful methyl(trifluoromethyl)dioxirane 1b should be the reagent of choice to carry out these key transformations. Thus, a mixture of compounds derived from the direct dioxirane attack at the β-(CH 3) 2C-H alkyl chain of one Hyi residue (compound 3a) or of one Val moiety (compounds 3b and 3c) could be obtained. Following convenient mixture separation, each of the new oxyfunctionalized macrocycles became completely characterized
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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