1,721,243 research outputs found
DSC study of ageing sequence in 6061 aluminium alloy - SiC whiskers composite
No full textResults of a Differential Scanning Calorimetry (DSC) investigation on precipitation hardening in solubilized 6061 aluminum alloy and its composites reinforced with SiC whiskers are reported. The exothermic and endothermic effects in DSC traces of these materials (in the solubilized state) have been attributed to phase formation and reversion on the base of the 6061 AA ageing sequence described in previous TEM studies. Apparent activation energies have been calculated according to the Ozawa method in non-isothermal conditions. The ageing sequence in composites is analogous to that of 6061 AA. It was found that the SiC whiskers reinforcement accelerates many steps of the ageing sequence. G.P. zone reversion and β' and β phase precipitations happen at lower temperatures in composite materials than in 6061 AA. The apparent activation energy for β' formation calculated for aluminum alloy and its composite gave rather similar results. The handbook solubilization method reported for 6061 alloy could not allow a complete dissolution of alloying elements for the composite
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
Natural aging characteristics of aluminium alloy 6061 reinforced with SiC whiskers and particles
No full textThe aging response at room temperature of aluminium alloy 6061 was compared with that of its composites containing SiC whiskers or particles. Materials were solutionized for 2 h at two different temperatures (529 and 557°C), quenched in cold water and naturally aged for up to 90 days. The improvement in mechanical characteristics was checked by means of hardness measurements. The microstructural features of aged samples were studied by differential scanning calorimetry. Both aluminium alloy and its composites showed the same aging sequence. Natural aging resulted in the progressive formation of primitive Guinier-Preston zones. Composites, when solutionized at 529°C, showed different aging kinetics from the aluminium alloy used as a matrix. In fact, in the case of composites such a temperature was not sufficient to allow complete solution of the alloying elements. This resulted in a lower aging rate. On the contrary, composites solutionized at 557°C showed the same kinetic behaviour as alloy 6061. Hence the driving force of the natural aging process depends on the concentration of alloying elements in the supersaturated solid solution only. The high density of dislocations close to the interface between the matrix and the ceramic reinforcement did not accelerate the aging response, contrary to what happens during artificial aging of composite materials
Mismatch repair gene deficiency and genetic anticipation in lynch syndrome. myth or reality
Full text linkEffect of glutathione on the "in vivo" reduction of a nitroxide free radical by electron spin resonance spectroscopy
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