1,720,987 research outputs found
Sensing and activation of anionic species by polyamine-based metal complexes
No full textThe role of metal complexes with polyamine ligands in selective binding of anions and their possible use
as optical chemosensors or biologically relevant hydrolytic agents for anionic substrates will be discussed
on the basis of some study cases from the work of the authors, with particular emphasis on the cooperative
action of metal cation and polyamine receptor in both the processes of interaction and sensing/
activation
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Encapsulation of metal cations and anions within the cavity of bis(1,4,7-triazacyclononane) receptors
No full textThe synthesis and characterisation of a new bis([9]aneN3) ligand (L4) containing two [9]aneN3
macrocyclic moieties separated by a 2,6-dimethylenepyridine unit is reported. A potentiometric and 1H
NMR study in aqueous solution reveals that ligand protonation occurs on the secondary amine groups
and does not involve the pyridine nitrogen. The coordination properties toward Cu(II), Zn(II), Cd(II)
and Pb(II) were studied by means of potentiometric and UV spectrophotometric measurements. The
ligand can form mono- and binuclear complexes in aqueous solution. In the 1 : 1 complexes, the metal
is sandwiched between the two [9]aneN3 moieties and the pyridine N-donor is coordinated to the metal,
as actually shown by the crystal structure of the compound [ZnL4](NO3)2·CH3NO2. L4 shows a higher
binding ability for Cd(II) with respect to Zn(II), probably due to a better fitting of Cd(II) ion inside the
cavity generated by the two facing [9]aneN3 units. The formation of binuclear complexes is
accompanied by the assembly of OH-bridged M2(OH)x (x = 1–3) clusters inside the cavity defined by
the two facing [9]aneN3 units, and pyridine is not involved in metal coordination. A potentiometric and
1H NMR study on the coordination of halogenide anions by L4 and its structural analogous L3 in
which the two [9]aneN3 units are separated by a shorter quinoxaline linkage, shows that bromide is
selectively recognised by L4, while chloride is selectively bound by L3. Such a behaviour is discussed in
terms of dimensional matching between the spherical anions and the cavities generated by the two
[9]aneN3 units of the receptors
Variations on the Author
Get PDF“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
Novel fluorimetric bulk optode membrane based on 5,8-bis((5’-chloro-8’- hydroxy-7’-quinolinyl)methyl)-2,11-dithia-5,8-diaza-2,6-pyridinophane for selective detection of lead(II) ions
No full textAppropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Get PDFWe 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
- …
