1,721,228 research outputs found
Tracing innovations and technology exchanges between Europe and China using on-site Raman microscopy and XRF. Enamelled objects at the 17th-18th century turn
No full textInternational audienceEnamelling, i.e. coating of a substrate with a layer of glass by firing, is one of the most sophisticated technologies developed to decorate artefacts. China has a long expertise in the production of ceramics and glass but for technical and aesthetic reasons, 17th century (Ming Dynasty and then Kangxi reign) Chinese decors were rather similar to those obtained on paper with lavish or watercolour techniques. These productions did not permit to represent a ‘realistic’ decor, as prepared on majolica, (soft-paste)porcelain and metal wares by European craftsmen who were capable of making copies of famous paintings. Actually, much information about the ingredients and production process remain imprinted in the matter accessible by spectroscopical methods, Raman and X-ray fluorescence spectroscopy. The rareness and high value of artefacts, particularly those made at the Imperial Palace under the guidance of (Jesuit) European masters, require the use of non-invasive mobile instruments. We present here an overview of the analytical study of French (enamelled watches, Limoges wares, soft-paste porcelain, etc.) and Chinese (wucai, fengcai, falangcai, huafalang, cloisonné etc.) artefacts prepared during the 17th and first part of the 18th century (Qing Dynasty). We are able to identify the first use of European ingredients (blue As-rich cobalt, white cassiterite) and recipes (purple-red Perrot’ gold nanoparticles, Naples yellow lead pyrochlore type pigments) for the preparation of ‘realistic’ decors on Chinese ceramics and enamels, which shed light on the technological exchange between Europe and China. The results are significant in terms of comparison with the written records analyzed by historians.COLOMBAN Philippe, ZHANG Yizheng, ZHAO Bing, « Non-invasive Raman analyses of huafalang and related porcelain wares. Searching for evidence for innovative pigment technologies », Ceramics International 43(15), 2017, 12079-12088.COLOMBAN Philippe, KIRMIZI Burcu, ZHAO Bing, CLAIS Jean-Baptiste, YANG Yong, DROGUET Vincent, « Non-invasive on-site Raman study of pigments and glassy matrix of 17th-18th Century painted enamelled Chinese metal wares : Comparaison with French enamelling technology » Coatings, 10, 2020, 471. COLOMBAN Philippe, KIRMIZI Burcu, ZHAO Bing, CLAIS Jean-Baptiste, YANG Yong, DROGUET Vincent, « Investigation of the pigments and glassy matrix of painted enamelled Qing Dynasty Chinese porcelains by noninvasive on-site Raman microspectroscopy, Heritage 3(3), 2020, 915-940. COLOMBAN Philippe, KIRMIZI Burcu, GOUGEON Catherine, GIRONDA Michele, CARDINAL Catherine, « Pigments and glassy matrix of the 17th-18th century enamelled French watches: A non-invasive on-site Raman and pXRF study » Journal of Cultural Heritage 2020, 44, 1-14.COLOMBAN Philippe, KIRMIZI Burcu, SIMSEK FRANCI Gulsu, « Cobalt and Associated Impurities in Blue (and Green) Glass, Glaze and Enamel: Relationships between Raw Materials, Processing, Composition, Phases and International Trade » Minerals, 11, 2021, 633.COLOMBAN Philippe, GIRONDA Michele, VANGU Divine, KIRMIZI Burcu, ZHAO Bing, COCHET Vincent, « The technology transfer from Europe to China in the 17th-18th centuries: Non-invasive on-site XRF and Raman analyses of Chinese Qing Dynasty enameled masterpieces made using European ingredients/recipes” Materials, 2021, 14, 743
Toward a Raman/FORS discrimination between Art Nouveau and contemporary stained glasses from CdSxSe1-x nanoparticles signatures
No full textCdSxSe1-x quantum dots received considerable attention in academic studies and as cut-off filters and indirect-gap semiconductors. These later compounds have also been used for artistic purposes to produce colored glass since the 1920s thanks to their bright colors. Because non-invasive conditions are now mandatory when considering objects belonging to the cultural heritage, the use of Raman and fiber optics reflectance spectroscopy has been identified as potential ones to obtain information about the nanostructure of six samples of historical glass produced between the late 1920s and modern days. The average elemental composition of the nanocrystals has been deduced processing both optical and vibrational data, and the result arising has been compared taking into account the several factors affecting the experimental results. The diffusion of zinc inside the nanocrystals has also been questioned by the shift caused on the CdS- and CdSe-like phonon band wavenumber and on the absorption edge wavelength. An investigation of the size distribution and crystallinity of CdSxSe1-x nanoparticles has been also performed considering those parameters that are mainly influenced by the disorder of the system, such as the extent of the Urbach tail and the Raman bandwidth. Thanks to the results obtained, discrimination between the more recent glass and the older Art Nouveau ones has been verified, leading to the identification of a useful analytical protocol for conservation purposes. Copyright (C) 2015 John Wiley & Sons, Ltd
UV-visible and IR spectroelectrochemical studies of FeVO4 sol-gel films for electrochromic applications
No full textThe sol-gel synthesis route, in combination with dip-coating deposition, was used for the preparation of FeVO4 films. TEM measurements of Fe/V (1 : 1)-oxide films heated at 400degreesC reveal that the films consist of a triclinic FeVO4-I and an orthorhombic FeVO4-II phases with a grain size of up to 50 nm. The electrochromic properties of the films were tested in 1 M LiClO4/propylene carbonate (PC) using various electrochemical techniques and in-situ UV-visible spectroelectrochemical measurements. The best compromise between the charge capacity per film thickness (Qd(-1) = -0.14 mC cm(-2) nm(-1)), electrochemical stability (>1000 cycles) and optical modulation (DeltaT(v)is = 0.15) was achieved in the potential range of 4.80 to 1.80 V vs. Li, which suggests that FeVO4 films can be used as counter-electrodes in electrochromic devices. Extensive IR-spectroscopy studies of FeVO4 films in charged/discharged states revealed the following spectra changes: (i) small charging (-0.01 mC cm(-2) nm(-1)) leads to a variation in the intensity of all the vibrational bands without shifting their frequencies, (ii) higher chargings bring about the intensity and frequency changes of bridging V-O...Fe and V...O...Fe stretchings showing that vanadium, and probably also iron, are involved in the insertion/extraction processes, (iii) below 500 cm(-1) broad absorption appears due to the Li+-O modes, which also remained in the IR spectra of discharged (bleached) states revealing the irreversible lithiation, and (iv) charging to -0.30 and -0.50 mC cm(-2) nm(-1) leads to the amorphisation of the film structure
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
Pigment analysis of Portuguese portrait miniatures of 17th and 18th centuries by Raman Microscopy and SEM-EDS
Full text linkSeventeen Portuguese miniature portraits on copper support from the Évora Museum collection (Portugal) were analyzed in situ
and nondestructively by Raman microscopy (RM), SEM-EDS, and stereomicroscopy. This work constitutes a great breakthrough in
the study of miniature paintings from the 17th and 18th centuries, since the chemical information known about this unique kind of
paintings are still scarce, and in particular, this exclusive collectionwas never been subjected to any physicochemical study. In this work, each portrait was examined in detail in order to characterize the pigments palette used by the miniaturists. The μ-Raman analysis, in particular, guaranteed an exceptional visualization and good individual identification of small grains of pigments
and other constituents of the pictorial layer. Using this technique, 19 compounds were identified, including bluish black covellite, a pigment rarely found in oil paintings. SEM-EDS was used as an important complementary technique to confirm the chemical nature of some pigments and to identify shell gold (gold dust) in some portraits. Overall, the pigments identified in this large set of old paintings are broadly consistent with those mentioned in the painting treatises of that time or reported in other more modern bibliographic sources
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
Fourier transform Raman and statistical analysis of thermally altered samples of amber
No full textWe report the experimental results that refer to a Fourier transform Raman (FT-Raman) survey of thermally altered Baltic and Romanian amber and the related statistical interpretation of data using principal component analysis (PCA). Although FT-Raman spectra show several small changes in the characteristic features of the investigated amber samples which may be used for discrimination, their visual recognition is relatively difficult, especially when interpreting data from archeological samples, and thus multivariate data analysis may be the solution to more accurately assign the geological origin based on overall characteristic spectral features. The two categories of amber have different behavior in terms of degradation during the experimental alteration, and Romanian amber is more susceptible to physico-chemical transformations by the aggressive environment when compared with Baltic amber. The obtained data were in accordance with the Fourier transform infrared (FT-IR) remarks published previously in a dedicated journal. The Raman technique is an alternative method that requires little to no sample preparation, water does not cause interference, and the spectra can be collected from a small volume (1-50 μm in diameter)
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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