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Reactivity of V2O5, MoO5 and WO3 in molten KNO3, studied by mass spectormetry
No full textThe reactivity of transition metal oxides MoO3, WO3 and V2O5 in molten KNO3 was studied by mass spectrometry of the gases evolved during heating, and X-ray diffraction of the solidified melts. The reaction stoichiometry showed that multistep reactions of the polyoxoanions occur. Intermediate products identified in the reactions of the oxides are hexa- and pentavanadates, tri- and dimolybdates, and ditungstate. After prolonged heating at 550°C, the reactions proceeded to form the monooxoanions: VO3^(?), MoO4^(2?) and WO4^(2?). The reactivity of the oxides decrease in the sequence: V2O5>MoO3>WO3, the inverse of the oxoacidity sequence deduced from the equilibria in ionic melts (WO3>MoO3>V2O5). The first reaction peak is determined by kinetics of the solid–liquid reaction, whereas further transformations of polyoxospecies are determined by their oxoacidity
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
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
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