1,720,969 research outputs found
Corrosion evaluation of artificially aged 6 wt-% tin bronze
No full textThis study concerns the corrosion behaviour of wrought 94 wt-%Cu-6 wt-%Sn (B6) bronze, whose composition is similar to materials used for outdoor bronze artefacts. In order to investigate the influence of the composition and microstructure on bronze corrosion processes, electrochemical ac and dc measurements in synthetic acid rain and chloride solutions were performed on the B6 binary alloy in comparison with an as cast bronze having a different degree of purity. Moreover, to perform thin layer activation (TLA) measurements of thickness loss, a suitable radio nuclide 65Zn (t1/2= 244 days) was produced on B6 specimens by a high energy proton beam. Artificial weathering experiments have been carried out by exposing activated and non-activated B6 specimens: To selected pollutants including NOx and SO2 at different concentrations to simulate urban and industrial atmospheres; in a cyclic salt spray cabinet to investigate the effects of marine environments; to basic (NH4)2SO4 solutions reproducing the aggressiveness of ammonia containing wet deposits. At the end of each test, the B6 corrosion rates obtained by weight loss determinations have been compared with those arising from the TLA method. Finally, the nature and microstructure of the surface oxidation products were investigated
Earthen plasters stabilized through sustainable additives: An experimental campaign
Full text linkThe earthen architecture widely spread in many countries of Europe, America, Asia, Africa, testifies to a particular material and immaterial culture. Nevertheless, it is a fragile heritage, which needs continuous maintenance. To encourage the preservation of such evidence of building techniques, an experimental campaign aimed at the development and evaluation of the performances of protective earthen plasters was undertaken. The durability of the plasters was improved through the addition of different additives, some of them traditional (such as lime and gypsum) and others innovative (geopolymers, enzymes), and resulting from industrial wastes (cement kiln dust). These additives have been selected considering low production costs and a reduced environmental impact, to improve the sustainability of the interventions. The performances of the earthen plasters in terms of efficacy (resistance to water erosion, water absorption, drilling, thermo-hygrometric cycles) and compatibility (changes in color and water vapor permeability) have been evaluated. Good performances were obtained by the different mixtures and, in particular, by those stabilized with gypsum. The results of this experimentation could find a useful application in the preservation of both ancient and new earthen built heritage
Effect of alkali cations on the methoxide ion addition to corands incorporating a thiopyrylium subunit
No full textA corrosion study on artificially aged bronzes of artistic interest
No full textThe corrosion behaviour of wrought and as-cast Cu94-Sn6 (B6 and G6, respectively) bronze (whose composition is similar to bronzes for outdoor artefacts) has been investigated. Artificial weathering tests have been carried out by exposing bronze specimens to selected pollutants as NOx and SO2 at different concentrations to simulate urban and industrial environments. Furthermore, the effects of marine atmosphere and acid rains have been investigated by ASTM B117-64 tests carried out on a cyclic salt spray cabinet and by immersion tests. The aggressive action of ammonia containing depositions was investigatedby adopting (NH4)2SO4 solutions.
Dta obtained with conventional techniques have been compared with those arising from TLA technique
Biodiversity and conservation correlation in the case of a Roman fresco located in a semi-confined environment
No full textThe subterranean heritage includes both natural and built sites with a strong cultural and historical fingerprint, some of each being enriched with painted surfaces. These semi-confined environments shelter specific and fragile biodiversity. This paper is focused on the case of a Roman painting (2nd-3rd century AD) located in an underground archaeological site in Marino Laziale, near Rome, which was opened to the public for the first time in 2021. The painted Mithraic scene is in a good state of conservation. The methodological approach included on site and laboratory investigations aimed to screen the main biological components associated to this hypogeum monument. The observed biodiversity included heterotrophic and chemolithotrophic microorganisms, and a mesofauna composed of eutroglophile and subtroglophile species, characteristic for many subterranean environments.
The ecological mechanisms and the conservation state of the work of art were analyzed for planning the best fruition practices. The aesthetic change, the possible mechanical damages induced by various organisms,
and the presence of significant amounts of organic matter, represent the main risks for painting conservation.
These aspects, beside the new possible risks associated with the presence of visitors, are under a constant and
ongoing conservation surveillance program
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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