1,721,124 research outputs found
Fonti per i materiali e le tecniche del disegno genovese a lapis, in (a cura di) M. C. Galassi e M. Priarone, L’underdrawing del disegno genovese. Dentro la genesi dell’opera grafica attraverso l’esame nell’infrarosso, Genova University Press, 2014, pp. 13-16
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Chromium doped γ-Al2O3 powders. Features of the electrical double layer and state of the surface species
No full textγ-Al2O3 samples, both pure and Cr doped, were prepared by heating at 470 °C sol-gel precursors obtained by using aluminum tri-sec-butoxide [Al(OC4H9)3] as the starting compound. The samples were characterized for phase composition (X-ray diffraction) and surface area (BET). Electrochemical determinations of the double layer reactivity of the pure and doped oxides were performed both by surface charge and by electrokinetic sonic amplitude (ESA) determinations. The interfacial electrostatic response is discussed and analyzed also with reference to the sample surface state obtained by X-ray photoelectron spectroscopy (XPS)
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
Octahedral tilting, monoclinic phase and the phase diagram of PZT
No full textAnelastic and dielectric spectroscopy measurements on PbZr1-xTixO3 (PZT) close to the morphotropic (MPB) and antiferroelectric boundaries provide new insight into some controversial aspects of its phase diagram. No evidence is found of a border separating monoclinic (M) from rhombohedral (R) phases, in agreement with recent structural studies supporting a coexistence of the two phases over a broad composition range x < 0.5, with the fraction of M increasing toward the MPB. It is also discussed why the observed maximum of elastic compliance appears to be due to a rotational instability of the polarization linearly coupled to shear strain. Therefore it cannot be explained by extrinsic softening from finely twinned R phase alone, but indicates the presence also of M phase, not necessarily homogeneous. A new diffuse transition is found within the ferroelectric phase near x similar to 0.1, at a temperature T-IT higher than the well established boundary T-T to the phase with tilted octahedra. It is proposed that around T-IT the octahedra start rotating in a disordered manner and finally become ordered below T-T. In this interpretation, the onset temperature for octahedral tilting monotonically increases up to the antiferroelectric transition of PbZrO3, and the depression of T-T(x) below x = 0.18 would be a consequence of the partial relief of the mismatch between the average cation radii with the initial stage of tilting below T-IT
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
Vanadium-doped TiO2 catalysts. A unifying picture of powders and suspensions
No full textAnatase powders, both pure and vanadium-doped, were subjected to acid-base leaching cycles. The different samples were characterized with respect to chemical composition, morphology and surface area. The effects of the different treatments on the chemical state of the surface and on the electrification at the solid-solution boundary were investigated, respectively, by X-ray photoelectron spectroscopy and electrophoretic mobility measurements. The stability of the aqueous suspensions was measured by sedimentation tests. The results of the different determinations are cross-compared in order to produce a general description of the catalysts.
Anatase powders, both pure and vanadium-doped, were subjected to acid-base leaching cycles. The different samples were characterized with respect to chemical composition, morphology and surface area. The effects of the different treatments on the chemical state of the surface and on the electrification at the solid-solution boundary were investigated, respectively, by X-ray photoelectron spectroscopy and electrophoretic mobility measurements. The stability of the aqueous suspensions was measured by sedimentation tests. The results of the different determinations are cross-compared in order to produce a general description of the catalysts
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