1,721,001 research outputs found
Chemical oxidation as repairing technique to restore corrosion resistance on damaged anodized titanium
Full text linkAnodized titanium shows an excellent resistance to pitting corrosion. However, it could be subject to failure in case of local removal of the oxide film due, for example, to incorrect handling during transport, installation, or use. Depending on part size and usage, an electrochemical anodizing treatment could be not feasible. In this case, localized chemical oxidation treatment could be used to recover damaged film and restore corrosion resistance. Chemical oxidation was performed on titanium by immersion in NaOH 10 M and H 2 O 2 10 M at temperature from room to 90 °C with duration ranging between 1 h and 72 h. Potentiodynamic tests in bromides 0.5 M were used to determine the effectiveness of the treatment in relation with the one obtained with anodic oxidation. Higher bath temperature led to faster growth of the film, however it has no effect on the final corrosion resistance. Breakdown potential in bromides increased with treatment duration. The establishment of a plateau occurs at earlier stage, as temperature is increased. Titanium samples anodized and then scratched, to simulate film mechanical removal, were recovered using chemical oxidation and initial corrosion resistance was restored. The suggested treatments for in-situ recovery are 72 h of exposure to NaOH or 6 h at H 2 O 2 at room temperature
Pitting corrosion on anodized titanium: Effect of halides
Full text linkTitanium corrosion resistance is high in the majority of environments. However, titanium is susceptible to different forms of corrosion, if exposed to high concentrated halides containing solutions. To face this corrosion problem, expensive titanium alloys are used. An alternative method, consisting of electrochemical anodizing treatment, which promote the formation of a compact titanium oxide on the surface, could be applied to increase titanium corrosion resistance. In this work, titanium samples anodized at 20V in H2SO4 0.5M have been tested in sodium fluorides, chlorides, bromides, and iodides at 0.5 and 2.0M in order to define halides aggressiveness
Corrosion resistance enhancement of chemically oxidized titanium through NaOH and H2O2 exposure
Full text linkTitanium owes its astounding corrosion resistance to a thin, compact oxide layer that is formed spontaneously when the metal is exposed to the environment. However, even titanium can be subject to corrosion in very aggressive environments. To enhance its corrosion resistance, it is possible to exploit the same mechanism that leads to the formation of the protective oxide layer and force its growth with an external contribution. Oxidation can be easily stimulated with the use of an electrochemical cell. However, when part geometry or dimensions do not allow the immersion in an anodizing bath, chemical oxidation can be used. This study compares corrosion resistance enhancement after NaOH and H2O2 treatment. Treatment duration and temperature, solution concentration, and quantity are optimized to achieve the best corrosion resistance with the least time and chemicals consumption, by maintaining the process easy to perform and safe for the operator
Titanium Anodization Efficiency through Real-Time Gravimetric Measurement of Oxygen Evolution
No full textAnodization is an easy and reliable treatment to improve titanium corrosion resistance in severe environments. In previous studies, its effectiveness in enhancing oxide film resistance in halides was correlated with anodization cell voltage. To increase treatment industrial applicability, energy efficiency has to be maximized. For this purpose, a gravimetric approach was applied to study oxygen evolution during titanium anodic oxidation. Anodization efficiencies, calculated from real time O2 evolution measurements, were used to determine the most efficient galvanostatic anodization treatment by comparing different anodic current densities, from 1 to 20 mA cm-2, and different electrolytes (H2SO4-K2SO4). Anodization cell voltages were correlated with oxide thickness through indirect spectrophotometric measurements to compare the amount of charge needed to reach a certain film thickness in different anodization conditions
Acute appendicitis: Position paper, WSES, 2013
No full textAppendectomy is one of the most frequently performed operative procedures in general surgery departments of every size and category. Laparoscopic Appendectomy - LA - as compared to Open Appendectomy - OA - was very controversial at first but has found increasing acceptance all over the World, although the percentage of its acceptance is different in the various single National setting. Various meta-analyses and Cochrane reviews have compared LA with OA and different technical details. Furthermore, new surgical methods have recently emerged, namely, the single-port/incision laparoscopic appendectomy and NOTES technique. Their distribution among the hospitals, however, is unclear. Using laparoscopic mini-instruments with trocars of 2-3.5 mm diameter is proposed as a reliable alternative due to less postoperative pain and improved aesthetics. How to proceed in case of an inconspicuous appendix during a procedure planned as an appendectomy remains controversial despite existing study results. But the main question still is: operate or not operate an acute appendicitis, in the meaning of an attempt of a conservative antibiotic therapy. Therefore, we have done a literature survey on the performance of appendectomies and their technical details as well as the management of the intraoperative finding of an inconspicuous appendix in order to write down - under the light of the latest evidence - a position paper. © 2014 Agresta et al.; licensee BioMed Central Ltd
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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