1,720,961 research outputs found
HyBridGel: a bridge between in-situ and laboratory analyses. A new minimally invasive procedure to identify organic colourants in complex matrices
No full textDealing with complex matrices can present an imposing challenge when it comes to identifying organic components. For scientists working in the field of cultural heritage, this challenge becomes even more complex, as they handle aged and deteriorated objects, often unique, and are required to address the most demanding questions while adhering to the principles of minimal or non-invasiveness. As awareness of the potential of Surface Enhanced Raman Spectroscopy (SERS) for organic analysis has grown, scientists have become increasingly creative in developing micro-sampling strategies and SERS supports to leverage the technique's ultra sensitivity without posing any risk to the integrity of artifacts.
In the context of this Ph.D. thesis, a recent in-situ extraction procedure, which exploits hydrogel’s ability to interact with water solution, was taken and pushed beyond its limits. The direct gel-supported liquid extraction method was employed for the extraction of one of the most elusive organic components, natural dyes, in the worst-case scenario: aged paint layers. The most ambitious goal was to adapt the extraction process into a comprehensive workflow capable of combining both SERS and mass spectrometry to conduct fingerprint investigations of the collected dyes.
The gel-supported liquid extraction method was adapted to Arabic gum, tempera, and oil-based paint mock-up containing pigments derived from madder, brazilwood, and indigo. The results demonstrate that the procedure's visible impact and extraction efficiency vary across different paint systems, primarily contingent on the type of binder employed. However, numerous unpredictable factors come into play in real-case scenarios. To address this challenge, the most effective extraction strategies were chosen for experiments involving reduced-scale gels, applied using a Pasteur pipette tip.
Once it was confirmed that the gel-supported liquid extraction could successfully extract dyes from various types of aged paint systems without causing any detrimental effects, it was subsequently applied to real case studies, encompassing historical paints and textiles, too. The procedure employed for printing inks from the early 19th century, hindered in non-invasive characterization due to fluorescence, has allowed the identification of two synthetic dyes. Utilizing gels, the extraction of natural dyes derived from madder and indigo was achieved from linen fragments found in Pharaoh Tutankhamun's tomb. Additionally, Kermes and flavonoid dyes were extracted from Hispano-Moresque textiles and identified using both SERS and mass spectrometry
Street art graffiti. Discovering their composition and alteration by FTIR and micro-Raman spectroscopy
No full textPaints used in street art are modern materials subjected to degradation processes, which are very complex and difficult to predict without taking into account of several factors. This study investigates three outdoor murals in Lazio, – namely “graffiti”, a word now used to indicate a spontaneous street art tendency consisting in images and writings realized by spray paints in public spaces to provoke passersby -with the aim to discover materials application techniques and chemical composition and figure out whether alteration phenomena occurred.
Twenty-two samples were collected, and their stratigraphy was studied by optical microscopy. Fourier Transformed Infrared spectroscopy was used to identify binders and their degradation products in paints and preparatory layers, while for characterization of organic pigments used in all different stratigraphy layers of samples micro-Raman spectroscopy analyses was carried out. Furthermore, micro-Raman spectroscopy allowed to study an unusual patina formed on the surface of a pink paint.
This information is useful for artists as well as for conservators, who must face numerous issues related to the preservation of this modern and labile kind of artistic expression, very fashionable nowadays but often created without care for materials duration. Conservation issues were also deepened by interviews with several contemporary mural authors.
Artists underlined how contemporary murals are a very heterogeneous means of expression. Different cultural tendencies coexisting result in different attitude towards conservation
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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