1,721,098 research outputs found
Corrosion and wear corrosion behaviour of a ceramic composite for use in biomedical applications
No full textIn view of the biocompatibility of both Si3N4 and TiN, it was reputed interesting to investigate the corrosion and wear corrosion behaviour of a ceramic Si3N4-35 vol % TiN composite in solutions simulating the composition of biological fluids. With this purpose, composite specimens were prepared and exposed to a 1% NaCl, in the absence and in the presence of 1% lactic acid. Tests were carried out under both corrosion and wear corrosion conditions and the results obtained were compared to those carried out on Ti6Al4V alloy, commonly used in biomedical applications. The morphology of the corrosion attack was investigated by SEM observations.
The results show that under corrosion conditions the ceramic material exhibits corrosion rates comparable to those exhibited by the metallic material. However, under combined wear corrosion conditions the ceramic composite is definitely more corrosion resistant
Fabrication and characterization of Hg-based Superconductive Thin Films
No full textWe have used a two step process to fabricate Hg-based thin films on various single crystal substrates, based on laser deposition of Hg-free precursors followed by high temperature synthesis in Hg atmosphere. Samples have been characterized by different structural and functional methods, including X-ray diffraction, and electrical and magnetic susceptibility investigations. Results indicate that the process leads to high quality Hg-based superconductive films, and point out a remarkable sensitivity on the synthesis parameters, whereas the choice of substrate material and laser deposition conditions appears to be not crucial. (C) 2001 Elsevier Science B.V. All rights reserved
Triboelectrochemical behaviour of a Si3N4–TiN ceramic composite and a titanium alloy commonly used in biomedical applications
No full textIn this paper the corrosion and tribocorrosion behaviour of a traditional metallic biomaterial (Ti6Al4V)
and a Si3N4/TiN (SN/TiN) ceramic composite are studied and compared during exposures to 1% NaCl and
1% NaCl + 1% lactic acid solutions.
Electrochemical impedance spectroscopy (EIS) data collected on Ti6Al4V in both neutral and acidic
solution have been interpreted on the basis of a double layer surface oxide film, which is completely
removed from the wear track during the sliding tests. Under these conditions, the impedance of the
depassivated region dominates the overall electrode impedance.
Previous EIS tests performed on SN/TiN evidence that even this material exposed to neutral solution is
covered by a double layer film, while a porous monolayer film forms in acid solution. Under pure corrosion
conditions, SN/TiN exhibits corrosion rates which are quite comparable to those measured on Ti6Al4V.
During tribocorrosion tests the EIS response of the ceramic material does not change much. Its corrosion
rates are two orders of magnitude lower than those measured on Ti6Al4V.
Profilometer analysis shows that on both materials most of overall tribocorrosion damage is due to
mechanical wear.
The tests suggest that SN/TiN is a promising biomaterials for applications where sliding conditions
occur
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
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