1,721,052 research outputs found
Reaction of [Pt-2(dppp)(2)(H)(3)][BF4] with styrene or phenylacetylene gives the same mu-hydrido mu-alkylidene derivative, [Pt-2(dppp)(2)(mu-H)(mu-CHCH2Ph)][BF4]
No full textThe reaction of the binuclear platinum hydride [Pt-2(dppp)(2)(H)(3)][BF4] with styrene or phenylacetylene gives the same mu-hydrido mu-alkylidene diplatinum complex, [Pt-2(dppp)(2)(mu-H)(mu-CHCH2Ph)][BF4], under the same mild experimental conditions. Experiments with deuterium-labeled reagents show that the hydrogenation of phenylacetylene does not occur through the transfer of the acetylenic proton and suggest that the hydrogenation to styrene as an intermediate step is not implied. The C-13 NMR spectra of the reaction product of an equimolecular mixture of [Pt-2(dPPP)(2)(H)(3)][BF4] and [Pt-2(dppp)(2)(D)(3)][BF4] with phenylacetylene suggest that fragmentation of the dimeric Pt2H3+ core does not occur. Possible phenylacetylene hydrogenation pathways are discussed
Statistical characterization of the mechanical properties of glass ceramics for structural applications
No full textGlass-ceramics (GC) are mostly produced in two steps. First, a glass is formed by a glass manufacturing process; then, the glass is cooled down and further reheated in a second step. In this heat treatment the glass partly crystallizes. GC share many properties with both glasses and ceramics, but the measured fracture toughness of GC is usually one order of magnitude higher than that of glass. This is probably due to the material underlying microstructure, because the crystallized phases in GC coagulate into grains within the amorphous matrix so that, while a crack opens, the grains can bridge its lips [1].
Here, we report the results of an experimental campaign directed towards structural applications, aiming at the characterization of the bending strength of glass ceramics. The considered tests were: (a) biaxial bending on square 100 mm × 100 mm specimens under concentric rings (r1= 45 mm, r2 =9 mm) according to UNI-EN 1288-5; (b) 4-point bending tests on 1000 mm × 360 mm specimens, according to UNI-EN 1288-5. Both 6 mm and 8 mm thick plies were tested: each sample was composed of 50 specimens for test type (a) and 20 specimens for test type (b), for a total number of 140 specimens.
We find that the probability distribution by Weibull is able to accurately represent the experimental data. The corresponding Weibull parameters are similar for both type (a) and type (b) tests, and for both the thicknesses. We find that the statistical distribution of the tensile strength for glass-ceramics has a much lower dispersion than that of glass. This property, together with the higher fracture toughness, renders glass ceramic more performant than glass for what structural applications is concerned
Binuclear hydride platinum(II) complexes: syntheses of [{Pt(P-P)}(2)(mu-CHCH2R)(mu-H)][BF4] (R = C6H5, H) and easy cleavage of a P-C bond in a chelating 1,4-bis (diphenyl)phosphinobutane (P-P)
No full textReactions of the binuclear platinum(II) trihydrido complex. [Pt-2{(Ph2P)(2)(CH2)(4)}(2)(H)(3)][BF4], with styrene or ethylene, at room temperature and low pressure, give mu-alkylidene, mu-hydrido cationic species [Pt-2{(Ph2P)(2)(CH2)(4)}(2)(mu-CHCH2R)(mu-H)][BF4] (R = C6H5, 1; H, 2) together with an unexpected phosphido-bridged binuclear platinum(II) compound (3), originating from cleavage of a P-C bond in the coordinated diphosphine. Complexes 1-3 are discussed on the basis of FAB MS, IR and multinuclear NMR spectra in solution. (C) 2000 Elsevier Science S.A. All rights reserved
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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