1,720,955 research outputs found
CHARACTERIZATION OF THE BISMUTH(III) BROMIDE-[2.2]-PARACYCLOPHANE (2/1) ADDUCT
No full textThe 2:1 charge-transfer molecular complex between bismuth bromide and [2.2]paracyclophane has been prepared and investigated by means of thermogravimetric, electronic and IR spectra and resistivity measurements. The X-ray structure was also determined: monoclinic, space group P2(1)/c, a = 7.896(3), b = 14.198(6), c = 10.803(8) angstrom, beta = 101.27(5)-degrees, Z = 2 and R = 0.0457. The structure is built up by polymeric linear chains of BiBr3 units interlayered by centrosymmetric hydrocarbon molecules. Two bromine atoms bridge adjacent metal atoms so that the co-ordination is very distorted octahedral with three short [2.595(3)-2.676(3) angstrom] and two longer bridging [3.325(3), 3.402(2) angstrom] Bi-Br bonds; the sixth site is occupied by a benzene ring of the [2.2]paracyclophane molecule. The complex shows high stability and characteristic electrical properties of a semiconductor at 25-degrees-C
TRANS-2-STYRYLBENZOTHIAZOLE COMPLEXES WITH MERCURY(II) HALIDES - SYNTHESIS, CHARACTERIZATION AND X-RAY CRYSTAL-STRUCTURE OF DIIODOBIS(TRANS-2-STYRYLBENZOTHIAZOLE)MERCURY(II)
No full textThe synthesis of trans-2-styrylbenzothiazole (L) and of its complexes with mercury(II) halides is reported. Complexes with the formulae [Hg2(L)Cl4], [Hg(L)Br2], [Hg(L)2I2] and [Hg(L)I2] were isolated and characterized by conventional chemical analysis, electronic and IR spectra and by thermal analysis. For one of these complexes, [Hg(L)2I2], the X-ray crystal structure was also determined. The complex consists of discrete [Hg(L)2I2] units in which mercury, located on a two-fold axis, shows a distorted tetrahedral coordination and the ligand molecules are bonded via nitrogen atoms with Hg-I = 2.61(2) angstrom and Hg-N = 2.36(1) angstrom bond distances
SYNTHESIS AND CHARACTERIZATION OF BISMUTH BROMIDE ARENE-PI COMPLEXES - X-RAY STRUCTURE OF BISMUTH(III) BROMIDE FLUORANTHENE-PARA-XYLENE (4/2/1)
No full textA structural and spectroscopic investigation of a charge-transfer complex of bismuth(III) bromide with fluoranthene is reported. Charge-transfer spectra of some complexes formed by BiBr3 with a series of polycyclic benzenoid and non-benzenoid hydrocarbons were recorded. The charge-transfer band energies, Ec.t., and the ionization potentials of the electron donors are linearly correlated with a slope of one. A linear correlation is also observed for Ec.t. and the first –* singlet transition energies of the benzenoid hydrocarbons. The crystal and molecular structure of bismuth (III) bromide–fluoranthene–p-xylene (4/2/1) was determined: crystals are triclinic, space group P, with a= 9.812(6), b= 11.199(7), c= 12.861 (8)Å, = 71.59(6), = 80.28(6), = 74.38(7)°, Z= 2, and R= 0.0848. The structure is formed by tetrameric Bi4Br12 centrosymmetric units in which three bromine atoms bridge adjacent bismuths, which show distorted octahedral co-ordination having five sites occupied by bromines and the sixth by a benzene ring of the fluoranthene at longer distances
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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