- Maria João Melo is a Full Professor at the Department of Conservation and Restoration of the Faculty of Sciences and ... moreMaria João Melo is a Full Professor at the Department of Conservation and Restoration of the Faculty of Sciences and Technology-New University of Lisbon and a researcher at the Associated Institute LAQV-Requimte and Medieval Studies Institute at NOVA.edit
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Research Interests: Art and Portuguese
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Paper presented at the VI Luso-Brazilian Simposium on Historical Cartography (Braga, Portugal, November 4-7, 2015).<br><br>In: Fernandes, Mário Gonçalves (Org.). Atas do VI Simpósio Luso-Brasileiro de Cartografia Histórica.... more
Paper presented at the VI Luso-Brazilian Simposium on Historical Cartography (Braga, Portugal, November 4-7, 2015).<br><br>In: Fernandes, Mário Gonçalves (Org.). Atas do VI Simpósio Luso-Brasileiro de Cartografia Histórica. Porto (Portugal): Faculdade de Letras da Universidade do Porto, 2016, p. 27-37. ISBN: 978-989-8648-56-3. URL: .<br><br>Authors:Juliana Buse de Oliveira<br>https://orcid.org/0000-0002-4561-0481<br>Maria João Melo<br>https://orcid.org/0000-0001-7393-6801<br>Maria da Conceição Lopes Casanovahttps://orcid.org/0000-0001-9889-381X<br>
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ABSTRACT Durante a Idade Média, a procura de novos métodos de ensino e pregação no meio clerical vai propiciar o aparecimento de obras de carácter simbólico-alegórico, comumente conhecidos por bestiários, que irão utilizar as... more
ABSTRACT Durante a Idade Média, a procura de novos métodos de ensino e pregação no meio clerical vai propiciar o aparecimento de obras de carácter simbólico-alegórico, comumente conhecidos por bestiários, que irão utilizar as características dos animais como modelos de comportamento. Apesar destes gozarem de uma enorme popularidade em Inglaterra e França, não temos conhecimento de qualquer exemplar produzido em Portugal. Por outro lado, no contexto monástico português do final do séc. XII, encontraremos três cópias do De Avibus, escrito por Hugo de Folieto em meados do século, cuja temática, semelhante à dos bestiários, se centra exclusivamente em aves. Esta obra foi produzida nos scriptoria de três dos mais importantes mosteiros do românico português. Esta sessão pretende dar a conhecer uma das obras singulares do românico, cujo programa iconográfico, associado a diversos modelos de circulação, revela informações acerca da sua origem e ligação a outras cópias europeias. Particular destaque será dado ao manuscrito iluminado Livro das Aves (Alc. 238), proveniente do Mosteiro cisterciense de Santa Maria de Alcobaça, que apresenta grande semelhança com a cópia francesa do Mosteiro de Clairvaux (ms. 177), actualmente conservada na biblioteca Municipal de Troyes. A partir do estudo em curso sobre o significado da cor na iluminura românica bem como da iconografia e do texto, acentuaram-se os enigmas acerca da origem e produção desta obra.
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In this chapter, the current state of knowledge regarding anthocyanin chemistry and the corresponding reversible multistate system of the chemical species is presented. Mathematical equations to account for the kinetics and thermodynamics... more
In this chapter, the current state of knowledge regarding anthocyanin chemistry and the corresponding reversible multistate system of the chemical species is presented. Mathematical equations to account for the kinetics and thermodynamics of the multistate system of anthocyanins are presented in a simple form to allow their use by non-specialists. The calculation of all rate and equilibrium constants of malvidin-3-glucoside in diluted solutions has been carried out to illustrate the use of these expressions. The irreversible reactivity of anthocyanins in foodstuffs, particularly in wine, leading to pyranoanthocyanins of the first and second generation is discussed. The use of the relative energy level diagrams of the multistate species together with their pH-dependent mole fraction distribution is reported and their usefulness emphasized. Using the morning glory flower as an example, the expression of its blue colour is rationalized by considering the thermodynamics and kinetics of the multistate system.
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Why do certain ancient natural dyes, such as indigo, preserve their colour so well while others, like brazilein, seem to degrade much faster? And how did mauveine change the world of colour? Will modern binding media, as vinyl paints,... more
Why do certain ancient natural dyes, such as indigo, preserve their colour so well while others, like brazilein, seem to degrade much faster? And how did mauveine change the world of colour? Will modern binding media, as vinyl paints, perform as well as a medieval tempera? Will it be possible to predict their durability? Photochemistry can answer many important questions about materials’ stability, providing new tools for the conservation of treasured artworks.
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ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full... more
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
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The Natural History and Science Museum of the University of Porto houses a collection of 45 models of fungi in papier-mâché from the 19th-century, which were used at the university until 2015 as didactic models. For the first time, the... more
The Natural History and Science Museum of the University of Porto houses a collection of 45 models of fungi in papier-mâché from the 19th-century, which were used at the university until 2015 as didactic models. For the first time, the materials and techniques used in the production of a Boletus edulis model were studied (vernacular name: cep, porcini). These sculptures, made to life-size scale, are painted in colors similar to those of the represented species (white, brown, and light brown). They are fixed to a rectangular base, which is painted black, and to which moss has been pasted. To fully characterize each color, at the molecular level, a multi-analytical approach was used, combining energy-dispersive x-ray fluorescence spectroscopy (micro-XRF) with fingerprinting techniques of Raman microscopy (microRaman and handheld Raman) spectroscopy and microFourier transform infrared spectroscopy (microFTIR). The papier-mâché was prepared with a groundwood paper to which kaolin and a ...
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Iron-gall inks are an essential element of our written cultural heritage that is at risk of a total loss due to degradation. This degradation leads to the loss of the support, particularly the cellulose-based support. Intending to... more
Iron-gall inks are an essential element of our written cultural heritage that is at risk of a total loss due to degradation. This degradation leads to the loss of the support, particularly the cellulose-based support. Intending to stabilize it, we have come a long way from the nineteenth-century cellulose nitrate laminations to the relatively recent phytate treatments; nevertheless, less invasive treatments are needed. To pave the way for developing safer and more sustainable treatments, tailored as much as possible to the object, this paper reviews the conservation treatments and the advances that have taken place over the last decade in our understanding of the degradation mechanisms of iron-gall inks, based on a careful selection of references to support a concise microreview. This discussion is based on the currently accepted models based on the Fe3+-gallate and the identification of degradation products for iron-gall inks observed in heritage objects, including manuscripts dati...
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The investigation and conservation of the Vienna Genesis, a Late Antique manuscript on purple parchment, included the study of parchment production and purple dyeing in the sixth century. The process of parchment making and of purple... more
The investigation and conservation of the Vienna Genesis, a Late Antique manuscript on purple parchment, included the study of parchment production and purple dyeing in the sixth century. The process of parchment making and of purple dyeing was recreated and compared with the Vienna Genesis and other manuscripts from the sixth and eighth centuries. Parchment made from the hides of young lambs and dyed with orchil resembled the folios of the Vienna Genesis. The results of material analysis and the study of parchment technology influenced decisions for the conservation and storage of the manuscript. Fragile areas of ink and parchment were stabilised with strips of adhesive coated Japanese tissue paper. The single folios are stored in folders of Japanese paper and museum matboard within a sink mat.
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Die Absorption von Licht verleiht Pigmenten ihre Farbe – und damit den Grund ihrer Existenz –, erzeugt aber auch angeregte Zustände, d. h. neue Moleküle mit einem Energieüberschuss, der über Abbauwege dissipiert werden kann.... more
Die Absorption von Licht verleiht Pigmenten ihre Farbe – und damit den Grund ihrer Existenz –, erzeugt aber auch angeregte Zustände, d. h. neue Moleküle mit einem Energieüberschuss, der über Abbauwege dissipiert werden kann. Photoabbauprozesse rufen langfristige, kumulierte und irreversible Farbveränderungen hervor (Verblassung, Dunklung, Ausbleichung), deren Prognose und Verhinderung schwierige Herausforderungen darstellen. Von all den Umweltrisiken, die Kulturgüter beeinträchtigen, ist Lichteinfall das einzige, das nicht ohne Auswirkungen auf die optimale Präsentation des Ausstellungsstücks reguliert werden kann. Lichtinduzierte Veränderungen betreffen nicht nur die Pigmente selbst, sondern auch ihre Wechselwirkungen mit dem Trägermaterial und Bindemittel und werden selbst wiederum durch die Umgebungsbedingungen verkompliziert. In diesem Kurzaufsatz untersuchen wir, wie Chemie (insbesondere in Form mehrskaliger analytischer Studien von Kunstwerken), Computermodellierung und physik...
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Additional file 1: Figure S1. Typologies of the manuscripts found in Portuguese collections. Table S1–S5. Microspectrofluorimetry and infrared data of samples from lac dye in medieval manuscript illuminations (12th–13th c.). Table S6.... more
Additional file 1: Figure S1. Typologies of the manuscripts found in Portuguese collections. Table S1–S5. Microspectrofluorimetry and infrared data of samples from lac dye in medieval manuscript illuminations (12th–13th c.). Table S6. Microspectrofluorimetry and infrared data of lac dye reconstructions. Table S7. Infrared spectra. Table S8. Percentage of calcium carbonate. Table S9–S12. Microspectrofluorimetry and infrared data of samples from brazilwood in medieval manuscript illuminations (end of 13th–15th c.). Table S13. Microspectrofluorimetry and infrared data of brazilwood reconstructions. Figure S2. Scatter plot representing the first three scores from the PCA model used to produce the dendrogram for lac dye (Lac) and brazilwood (BW) based paints. Link to video in: https://www.dropbox.com/s/4vfyc63cjsvn7j1/Heritage Sci Nabais P_ Scatter plot.mp4?dl=0 .