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KINETICS OF THE REACTION OF DICHLORO-TRANS-RAC-1,2-DIAMINOCYCLOHEXANEPLATINUM(II) AND DICHLORO-CIS-MESO-1,2-DIAMINOCYCLOHEXANEPLATINUM(II) WITH PYRIDINE
No full textThe kinetics of the reaction [Pt(dach)Cl2] + py- [Pt(dach)(py)CI]Cl (dach = either trans-rac- or cis-meso-1,2-diaminocyclohexane, py = pyridine) has been studied in dimethylformamide (dmf) solution, under pseudo-first-order conditions (excess of pyridine), in the range 50-80-degrees-C, by measuring the increase in conductance of the solution. In dmf the products behave like weak electrolytes, with dissociation constants of about 1.4 x 10(-3) mol dm-3 . The reactions were found to be reversible under the experimental conditions. Owing to the uncertainty in evaluating the equilibrium concentrations, the kinetic constants k(obs) have been calculated from the initial slopes (up to 1 5% conversion) of first-order plots. Their values obey the equation k(obs) = k1 + k2[py], k1 being about two orders of magnitude lower than k2. The values of k(obs) for the cis derivative are always slightly but significantly higher than those of the trans. The activation parameters have been evaluated only for k2, since the k1 values are affected by too high uncertainties: DELTAH(double dagger) trans 76(1), cis 79(1) kJ mol-1; DELTAS(double dagger) trans -101(3), cis -92(3) J K-1 mol-1. The higher rate for the cis isomer is interpreted in terms of higher flexibility of the diamine chelate ring
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
Schiff base complexes of oxo cations. I. Uranyl complexes with tetradentate optically active Schiff bases of salicylaldehyde
No full textThe synthesis and properties of uranyl complexes with tetradentate ligands of formula UO2 (saldiamine). L (where saldiamine is the Schiff base N,N′diamine bis(salicylideneimine), L is a solvent molecule and the diamines are ethylenediamine, (+) propylenediamine, (+) and meso butanediamine, (+) and meso cyclohexanediamine, (-) and meso stilbenediamine) are reported. I.R., electronic and circular dichroism spectra are also discussed
Use of Chiral Diamines in the Synthesis of ‘Half Unit’ Schiff Base Cu(II) Trinuclear Complexes: A Possibility of Chirality Induction
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