1,721,004 research outputs found
Cyclometalation via carbon–fluorine bond activation induced by silver particles
No full textOn treatment with either freshly prepared silver nanoparticles or silver particles mechanochemically generated by stirring silver(I) oxide in dichloromethane, the complex [Cp*IrCl2(κC-MeNC3H2NCH2C6F5)] underwent a rapid and clean cyclometalation involving carbon—fluorine bond fission to afford the product [Cp*IrCl(κC2-MeNC3H2NCH2C6F4)]
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
Synthesis of Perfluoroaryl Heterocycles To Provide Synthons For Crystal Engineering Using π−π Stacking Interactions
No full textApproximately 42 new arene-perfluoroarene compounds were synthesised by the reaction of pentafluorophenyl derivatives (C₆F₅R; R= CN, Br, Cl, I, CHO, CF₃, H) with imidazole, benzimidazole, parazole, indazole and their derivatives such as 2-methylimidazole, 4-methylimidazole, 2-phenylimidazole and 2-methylbenz-imidazole. Attempts to synthesize 1-(2,3,5,6-tetrafluoropyridyl)pyrazole and 1-(2,3,5,6-tetrafluoropyridyl)indazole were unsuccessful. However, these reactions were achieved using different solvents, varying amounts of solvents and varying temperatures. Various chemical analytical techniques, such as NMR spectroscopy, mass spectrometry, infrared spectroscopy, single-crystal X-diffraction and micro-elemental analysis, were used to characterise the compounds. The crystallization of these compounds was performed by the slow evaporation of their solutions in different solvents at ambient temperature. Single crystal structures were obtained for 1-(2,3,5,6- tetrafluoropyridyl)-2-methylbenzimidazole, 1-(4-bromo-2,3,5,6-tetrafluorobenzyl)-3-benzyl-4-methylimidazolium bromide and 1-(2,3,5,6-tetrafluoropyridyl)-3-benzyl-4-methylimidazolium bromide and this result has shown that π-π stacking interactions have an essential role in the packing of these compounds
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
Rendering Titanium Superhydrophobic
Full text linkTwo methods are reported herein to render titanium metal superhydrophobic. A superhydrophobic surface by definition is one that shows a water contact angle of equal to or greater than 150˚,(1) while in contrast bare titanium metal is hydrophilic and exhibits a water contact angle of 73±3˚.(2) Titanium metal is extremely reactive in air and rapidly forms a self-repairing oxide layer, which makes the necessary surface modification of the material to render it superhydrophobic challenging.
The first method employed in this work consists of a cold compression procedure whereby copper powder that has been previously rendered superhydrophobic by galvanic deposition of silver followed by treatment with 1-dodecanethiol is compressed onto titanium powder. The resulting compact consists of a superhydrophobic copper layer on a titanium substrate. The superhydrophobic copper layer is robust in that if it is damaged, the damaged layer can be abraded away to expose a new, fresh superhydrophobic copper layer beneath. Each successive layer exposed after abrasion throughout the superhydrophobic copper portion of the material is shown to exhibit the same wetting characteristics with regards to water roll-off angle.
The superhydrophobic titanium material prepared by this method exhibited a static water contact angle of 157±1º and water roll-off angles of 3.8±0.9º. The method was also successfully applied to aluminium powder, which showed a water roll-off angle of 4.2±0.4˚.
An additional superhydrophobic titanium material was prepared using this method which had a polyfluoroalkylthiol surface modifier, 1H,1H,2H,2H-perfluorodecanethiol, used in place of the 1-dodecanethiol. This material showed no statistically significant difference in wetting behaviour from its alkylthiol treated counterpart, with a water roll-off angle of 3.4±0.5˚ and a static water contact angle of 159±3˚.
The second method employed in this work was applicable to a foil form of titanium. It involves the deposition of copper onto a titanium foil, followed by galvanic reduction of silver onto the copper plate and adsorption of 1H,1H,2H,2H-perfluorodecanethiol in a self-assembled monolayer. Difficulty was encountered in getting a reproducibly adherent copper plate onto the titanium foil, and two methods were experimented with to find optimum conditions for an adherent copper deposit.
The first strategy used to deposit copper onto titanium involved a high voltage capacitor discharge across a titanium electrode in an acidic copper sulfate solution to destroy the native oxide layer present on titanium. A copper electroplate immediately followed this step, though unfortunately none of the deposits prepared in this manner passed adherence tests. The second method involved an anodic etching step before deposition of copper and showed much improved adherence over the first method, but was inconsistent and the copper coatings were non-uniform.
The superhydrophobic titanium materials prepared on titanium foils using both methods of copper deposition showed the same roll-off angles for an applied glycerol droplet as a purely superhydrophobic copper foil. A previous publication1 has quoted superhydrophobic copper foil prepared by the same method as having a water contact angle of 173±1˚ and a water roll-off angle of 0.64±0.04˚. Extrapolating from the materials sharing the same glycerol roll-off angles gives some confirmation that a superhydrophobic surface has successfully been applied to titanium foil in this work
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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