1,720,959 research outputs found
Multiscale characterization of corrosion in archaeological artefacts from Motya (Sicily, Italy) through X-ray microscopy
No full textHere we presented a multi-analytical approach (Multiscale X-ray Microscopy, Micro-Raman, SEM, HR- FESEM- EDS and EMPA) to explore corrosion mechanisms in different type of metal artefacts from Motya (Sicily, Italy) to gain the maximum information with the minimum sampling. Indeed, the elemental analysis provides key information on the role of alloying elements in production technology and corrosion process, whereas the structure information from Multiscale Xray Microscopy (XRM) enables multilength scale visualization of whole objects and provides the spatial distribution of corrosion phases.
The results revealed the internal structure of the artefacts and the structural discontinuities which lead the corrosion, highlighting the compositional differences between the tip and the head of the iron nail (Bernabale et al., 2022). All copper-based artefacts were exposed to bronze disease corrosion induced by the presence of the reactive cuprous chloride (CuCl) located at the interface between external corrosion layers and the surviving metal core. In a Cu nail arsenic was forced outwards along inter-granular channels and it combined with Fe atoms at Cu grain boundaries, leading to the formation of copper-iron arsenate. Binary and ternary alloys revealed marked Cu and Sn selective corrosion and thicker patina compared with Cu metal due to the presence of Sn in chlorine-rich environment. The dissolution factor of copper in these alloys showed a great variability. In addition, the occurrence of cracks inside the bronze needle acted as new corrosion interfaces and involved the formation of complex and periodic stratified corrosion layers, leading to a complete mineralized structure (Bernabale et al. 2023)
Exploring the chemical composition and corrosion patterns of arrowheads used in the Siege of Motya (397 BC) through a multi-analytical approach
No full textThis study examines a set of bronze arrowheads involved in the Siege of Motya (Italy) and aims to determine their microstructures, corrosion patterns and production techniques using Scanning Electron Microscope, X-ray maps, Electron Microprobe Analysis and X-ray diffraction. The arrowheads characterized by plane and conical shapes are made from Cu-Sn-alloy, featuring Liesegang rings with streaks of Sn-oxide interposed between Cu2O and Cu2(OH)3Cl layers. Those of pyramidal or lanceolate shapes are made from Cu-Pb-Sn alloy and contain different corrosive products triggered by exposure to high levels of chloride-rich conditions. These results have highlighted an interesting correlation between alloy microstructures, compositions, typology and geographic provenance, and thus provide new insight on the weaponry and poliorcetics of the Syracusan army that led to the defeat of Motya in 397/6 BC
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
3D imaging of micro-segregation and corrosion behavior of alloying elements in archaeological artefacts from Motya (Sicily, Italy)
No full textMultiscale X-ray Microscopy, SEM, HR-FESEM- EDS and EMPA techniques have been used to explore the corrosion behavior of copper-based artefacts from the Phoenician-Punic site of Motya (Sicily, Italy). The stress corrosion, due to forging conditions, and dealloying have been investigated using 3D-imaging. At sub-micro-scale the results highlighted grain boundaries micro-segregations induced by As and the occurrence of copper-iron arsenate layers in a Cu-nail. Binary and ternary alloys revealed a marked enrichment of Sn content and a selective corrosion of Cu as determined by the calculation of dissolution factors
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
Investigating corrosion systems in archaeological artifacts from Motya (Sicily, Italy): A Micro-Raman Spectroscopy and Correlative Imaging approach
No full textRaman spectroscopy is a non-destructive technique which can provide a unique fingerprint of the corrosion products embedded within the patina of archaeological artifacts, leveraging molecular vibrational modes analysis. Its sensitivity and capability for discriminating between corrosion products make it a valuable tool, particularly due to its ability to delve into structural characterization at the microscale and produce qualitative phase distribution maps.
In this research, we employed micro-Raman spectroscopy in combination with correlative imaging techniques and imaging tomography to investigate corrosion phenomena in nails from the Phoenician-Punic site of Motya (Sicily, Italy). To accomplish this, we used Correlative Light and Electron Microscopy, Micro-Raman spectroscopy, and X-ray Microscopy. This approach involves the integration of complementary investigation techniques to perform multiscale and multimodal experiments, all focused on the same area of interest.
The aim of this study is to investigate the stratification of corrosion layers and the mechanism of transformation of Fe products formed under specific conditions that occurred in lagoon-like environment. Recognizing the spatial distribution and interconnectivity of mineral phases and cracks within corrosion layers was crucial for comprehending the corrosion process's evolution. The results showed remarkable differences in the condition of the nails and provided 3D imaging of the internal structures, revealing cracks and the original shape of the nails
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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