1,720,956 research outputs found
New developments in early industrial stained glasses
No full textIn the present work, 50 samples of stained glass have been studied in order to disclose the improvements in glass production introduced after the growth of industry in the late 18th and early 19th centuries; the large scale production of glass and the development of new techniques led to a revival of stained glass manufacture, culminated during the late 19th century with the addition to the batch of many new colouring agents, or syhnthetic versions of the old ones, and synthesized raw materials (such as Solvay processed soda).
The sample repertory includes both transparent and opalescent glasses produced by some Italian, German and American glassworks between the late 19th and the first half of the 20th centuries. All samples have been preliminarily analyzed by SEM-EDS and XRF in order to characterize the batch composition and the colouring agents. XRD has been utilized as well to identify crystalline phases employed as opacifying agents.
Based on major element contents, the majority of samples can be considered as soda-lime-silica glasses, with few examples of mixed alkali-lime and lead-potash glasses. Concerning coloured transparent glasses, the addition of new colouring agents synthesized during the 19th century such as pure cobalt (mainly used for blue tints), cadmium (yellow and orange), selenium (pink and amber) and zinc (associated with sulphur to produce a deep red tint) has been confirmed. Moreover, high contents of calcium and fluorine have been detected in all opalescent samples by SEM-EDS and XRF (XRD analysis confirmed the presence of fluorite, CaF), while zirconium (introduced as zircon, ZrSiO4 or zirconium dioxide,ZrO2), has been detected as well in some samples
Characterization and contemporary replicae of Art Noveau coloured glass
No full textCurrently the importance of the application of non-invasive and portable techniques to the characterization of glass is well known. However, despite the large number of publications on medieval glass, few studies have been performed on early modern glass.
Since the opportunities to sample or to move the work of art out of the conservation location are very limited, the application of non invasive and portable techniques appears to be the best way to perform an in-depth characterization of the chromophores and raw materials even though the complexity of interpreting the results and the lack of references necessitate a preliminary phase of testing on standard and reference samples.
In this study a collection of colored and opalescent glasses from the first half of the 20th century and some standard samples of cobalt and cadmium glasses produced ad hoc at the Vicarte Centre (Universidade Nova de Lisboa) were analyzed using both traditional (XRF, SEM-EDS, XRD and UV-Vis-NIR) and portable and non-invasive techniques (XRF, FORS).
The standard samples consist of 21 glasses different base compositions (soda-lime, potash and mixed alkali) and different amounts of chromophores. For cobalt colored glasses different amounts of cobalt (0.5, 0.75 and 1% wt) were added to each base composition (9 samples). Also, yellow to orange and ruby red colorations were obtained by modulating the cadmium/sulfide and cadmium/selenium ratios.
The cobalt blue glass absorption spectra detected by FORS are usually characterized by three sub-peaks located around 530 nm, 590 nm and 650 nm due to the cobalt tetrahedral coordination. A change in the base composition of the glass could, however, affect the three-peak position due to a change in the ligand field strength.
The influence on the FORS spectra of a different base composition and amount of soda present in the glasses (detected by SEM-EDS and XRF) was studied. For glasses with soda content under 15% (some soda-lime samples and mixed base glasses), the resolution of the three-peak absorption band of cobalt is poor. The band appears to be broad, unsymmetrical, and centered around 550 nm even though the characteristic triplet was detected when the amount of soda increased to between 15% and 29%. A shift of about 10 nm in the position of the peaks can be observed in all glasses with a potash base.
The study of the glasses colored by CdS and Se is still in progress, and the results will be available soon
The 'Madonna and Child Enthroned with Saints' of Ambrogio Lorenzetti in the St. Augustine Church (Siena, Italy): Raman microspectroscopy and SEM-EDS characterisation of the pigments
No full textRaman microspectroscopy combined with scanning electron microscopy was applied to the investigation of the Madonna and Child Enthroned with Saints of Ambrogio Lorenzetti (early 14th century; St. Augustine church, Siena, Italy). A detailed investigation of both the materials used for the wall painting and the alteration products was provided in order to increase the level of accessibility of this masterpiece and to stimulate its restoration. The results showed that the pigments used for this wall painting were those widely used by medieval painters: chalk white, white lead, yellow ochre, red ochre, red lead, cinnabar, Siena earth, green earth, verdigris, azurite, and carbon black. Gilded tin foil has been further used for the decoration of the haloes. The alteration products mainly consist of Ca sulfates and Ca oxalates. Fungal spores were further observed in correspondence to the application of lead-based pigments. © 2014, Springer-Verlag Berlin Heidelberg
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
The Faragola Ceramic Collection: Ceramic Production, Consumption and Exchange in Seventh-Century Apulia
No full textA collection of 30 ceramic samples, 16 of coarse wares and 14 of fine painted wares, have been investigated by optical microscopy, scanning electron microscopy, inductively coupled plasma optical emission spectrometry, inductively coupled plasma mass spectrometry and neutron activation analysis. Further samples of clayey sediments, both locally outcropping and found within the settling tank, have been submitted to the same analytical techniques for comparison with the ceramic collection. The results demonstrated that local clayey sediments were used as received for the production of coarse wares. The same raw materials were sieved and/or refined by decantation for the production of fine painted wares, which, in fact, provided results that were perfectly comparable with those for the clayey raw materials found within the settling tank. The Faragola productions were distinguished from the neighbouring Apulian productions according to petrographic features (the presence of leucite-bearing volcanic rocks and Mn-rich wads) and their bulk chemical composition. © 2013 University of Oxford
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