1,720,974 research outputs found
Synthesis and coordinating properties of the facultative Sb2O- and As2O-donor ligands O{(CH2)(2)ER2}(2) (E = Sb or As; R = Ph or Me)
No full textThe new mixed Sb2O-donor ligands O{(CH2)2SbR2}2 (R = Ph, 1; R = Me, 2) with flexible backbones have been prepared in good yields as air-sensitive oils from reaction of NaSbR2 with 0.5 mol equivalents of O(CH2CH2Br)2 in thf solution. The As2O-donor analogues, O{(CH2)2AsR2}2 (R = Ph, 3; R = Me, 4) were obtained similarly from LiAsPh2 or NaAsMe2, respectively and O(CH2CH2Br)2, although ligand 4 appears to be considerably less stable with respect to C–O bond fission under some conditions than the other ligands. Using O(CH2CH2Cl)2 leads only to partial substitution by the SbPh2? or AsPh2? nucleophile. These ligands behave as bidentate chelating Sb2- or As2-donors in the distorted tetrahedral [M(L–L)2]BF4 (M = Cu or Ag; L–L = 1–4) on the basis of solution 1H and 63Cu NMR spectroscopic studies, mass spectrometry and microanalyses. Crystal structures of three representative examples with Cu(I) and Ag(I) confirm the distorted tetrahedral Sb4 or As4 coordination at the metal and allow comparisons of geometric parameters. The crystallographic identification of an unexpected Cu(I)–Cu(I) complex, [Cu2{Me2As(CH2)2OH}3](BF4)2, obtained as a by-product via C–O bond fission within ligand 4 is also reported. The distorted octahedral [RhCl2(L–L)2]Cl and the distorted square planar cis-[PtCl2(L–L)] (L–L = 1 or 2) are also described. The ether O atoms are not involved in coordination to the metal ion in any of the late transition metal complexes isolated
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
Tungsten(VI) and molybdenum(VI) complexes with soft thioether ligand coordination: synthesis, spectroscopic and structural studies
No full textReaction of WX6 (X = Cl or Br) with O(SiMe3)2 in CH2Cl2, followed by addition of MeCN and a further equivalent of O(SiMe3)2 in CH2Cl2 gives [WO2X2(MeCN)2] in situ, which subsequently react with the dithioethers MeS(CH2)2SMe, iPrS(CH2)2SiPr or 1,4-dithiane to afford the first series of WVI thioether complexes, [WO2X2(dithioether)]. The very moisture-sensitive yellow complexes have been characterised by microanalysis, IR, 1H and 13C{1H} NMR spectroscopy, which indicate cis-dioxido and trans-dihalide arrangements in the monomers with two thioether donor atoms completing the very distorted octahedral geometry (confirmed by a crystal structure of [WO2Cl2{iPrS(CH2)2SiPr}]). The strongly polymerised WO2X2 compounds themselves are not useful synthons for the preparation of the WVI thioether complexes and substitution of the dimethoxyethane ligand in [WO2Cl2{MeO(CH2)2OMe}] by dithioethers is also incomplete. Molybdenum(VI) dioxidodichloride thioether complexes of the form [MoO2Cl2(L)] (L = iPrS(CH2)2SiPr, 1,4-dithiane, 2-[15]aneS2O3, 2-[14]aneS4 and 2-[12]aneS4) ([15]aneS2O3 = 1,4-dithia-7,10,13-trioxacyclopentadecane, [14]aneS4 = 1,4,8,11-tetrathiacyclotetradecane, [12]aneS4 = 1,4,7,10-tetrathiacyclododecane) and the unusual dinuclear [Mo2O4Cl4{o-C6H4(CH2SMe)2}2] are obtained by direct treatment of MoO2Cl2 with the appropriate ligand. The [Mo2O4Cl4{o-C6H4(CH2SMe)2}2] adopts an unexpected metallocyclic structure with cis-MoCl2 units and bridging bidentate dithioether (confirmed crystallographically). The structure of a new polymorph of [WO2Cl2{MeO(CH2)2OMe}] is also described
Synthesis, spectroscopic and structural systematics of complexes of germanium(IV) halides (GeX4, X = F, Cl, Br or I) with phosphane oxides and related oxygen donor ligands
No full textThe first series of phosphane oxide complexes of germanium(IV) halides have been prepared, including trans-[GeF4(R3PO)2] (R = Me, Et or Ph), trans-[GeCl4(Et3PO)2], fac-[GeCl3(Me3PO)3]2[GeCl6] and cis-[GeX2(Me3PO)4]X2 (X = Cl or Br) and characterised by IR and multinuclear NMR (1H, 19F{1H} and 31P{1H}) spectroscopy. Crystal structures of all the above (except trans-[GeCl4(Et3PO)2]) are described. Remarkably, under mild conditions Me3PO displaces halide ligands from GeX4 (X = Cl, Br) to form the cationic species above. Ph3AsO forms trans-[GeF4(Ph3AsO)2], but reaction of Ph3AsO or Me3AsO with GeCl4 leads to the corresponding R3AsCl2. The complexes [GeF4(MeCN)2], [GeF4(thf)2] and [GeF4(MeOCH2CH2OMe)] are also described and the relative Lewis acidities of GeX4 established
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