On the hierarchical use of colourants in a 15th century book of hours

An illuminated Book of Hours (in use in Chalon-sur-Sa\uf4ne) currently owned by the Museo Civico di Arte Antica and displayed in the prestigious Palazzo Madama in Torino (Italy) was investigated by means of optical microscopy, fibre optic reflectance spectroscopy, fibre optic molecular fluorimetry, X-ray fluorescence spectrometry and Raman spectroscopy. The aim of the scientific survey was to expand the knowledge of the manuscript itself and on the materials and techniques employed by Antoine the Lonhy, the versatile itinerant artist who decorated the book in the 15th century. The focus was to reveal the original colourants and to investigate the pigments used in rough retouches which were visible in some of the miniatures. The investigation was carried out in situ by portable instruments according to a non-invasive analytical sequence previously developed. It was evident that the use of different pigments by the master was ruled, at least partially, by a hierarchical scheme in which more precious materials were linked to the most important characters or details in the painted scene

Phase Nanoengineering via Thermal Scanning Probe Lithography and Direct Laser Writing

Nanomaterials derive their electronic, magnetic, and optical properties from their specific nanostructure. In most cases, nanostructured materials and their properties are defined during the materials growth, and nanofabrication techniques, such as lithography, are employed subsequently for device fabrication. Herein, a perspective is presented on a different approach for creating nanomaterials and devices where, after growth, advanced nanofabrication techniques are used to directly nanostructure condensed matter systems, by inducing highly controlled, localized, and stable changes in the electronic, magnetic, or optical properties. Then, advantages, limitations, applications in materials science and technology are highlighted, and future perspectives are discussed

FTIR techniques applied to the detection of gelatine in paper artifacts: from macroscopic to microscopic approach

International audienceIn order to render paper hydrophobic for ink and thus adequate for writing, gelatine has been largely used. To this day, it is still employed in conservation workshops as an adhesive or a sizing agent, for instance, during the treatment of iron gall ink manuscripts. Various types and concentrations of gelatine are recommended, depending on the desired effect, but little information is available regarding to the physical distribution of gelatine in the paper. This aspect is however determinant for a better control of conservation treatments. In this work, we investigate the possibilities offered by FTIR microscopy for the measurement of the gelatine distribution in paper. Laboratory papers were preliminary treated with different types of gelatine and then embedded in a resin and cut in thin slices. Mapping techniques enable to compare the penetration of different types of gelatine in a semiquantitative way. The performance of conventional laboratory equipment and synchrotron radiation experimental setup are discussed

A protocol for non-invasive analysis of miniature paintings

The characterisation of palettes used in medieval manuscript illumination is an important task from the historical-artistic point of view, but a hard one from the scientific point of view: miniatures cannot be sampled, it is unsuitable to use techniques operating in contact (i.e. IR in ATR mode) and to perform long-lasting analytical sessions, due to the stress that can be inferred to manuscripts. For these reasons it is necessary to use analytical techniques either non-invasive and fast; moreover, in most of cases it is necessary to work in situ with portable instruments. Among available techniques working in portable versions, Raman spectroscopy is the most informative, due to its diagnostic power; it requires, though, long time of analysis. XRF spectrometry is a powerful alternative but, being an elemental technique, in some cases it does not yield accurate results. UV-visible-NIR spectrophotometry in reflectance mode with fibre optics (FORS) can be promising as preliminary technique with some apparent limits. In this work a protocol of analysis is proposed for characterisation of miniature paintings on manuscripts in non-invasive way, using only portable techniques and performing in situ analysis. The protocol allows identification of colorants by successive application of complementary techniques, exploiting the advantages of each technique. First of all a palette with several pigments, dyes and lakes on parchment has been prepared with colorants that were in use in Middle Ages; paints have been prepared in gum Arabic and in egg white, according to ancient recipes described in medieval textbooks such as De arte illuminandi by anonymous, Compositiones ad tingenda musiva by anonymous and Il libro dell\u2019arte by Cennino Cennini. This palette is the base on which to build a database of spectroscopic analysis, reproducing a situation similar to the one present on manuscripts. It is important, therefore, to stress out the fact that spectra collected from this palette are more reliable that spectra obtained from analysis of colorants in powder. Protocol is started with an overall investigation with FORS, collecting spectra from all painted areas of the manuscript and comparing them with the database. This allows to identify almost 60-70 % of the colorants present. Then visual inspection of the paintings is performed with a digital camera connected with a 10-80x microscope, in order to have a clear image of areas that show uncertain FORS spectra, i.e. mixtures of pigments, altered paints, etc. Then XRF spectrometry is performed in order to characterise metal pigments (i.e. gold, silver and copper pigments), to verify the presence of overlapping layers, to identify mordants for dyes and lakes and to identify contaminants in pigments yielding information useful to study the provenance of raw materials for colorants. At this stage almost 90% of colorants can be identified. Finally Raman spectroscopy is used for the most uncertain cases. After application of these techniques a wealth of information is obtained, causing little or no stress at all to the manuscripts under analysis

Non invasive analysis of miniature paintings: proposal for an analytical protocol

The characterisation of palettes used in manuscript illumination is a hard analytical task, due to value and fragility of the analysed items. Analysis on miniatures must be necessarily non-invasive and fast and requires the use of several techniques since no single technique is able to provide all information needed. In this work a four-step analytical protocol is proposed for non-invasive in situ characterisation of miniature paintings. The protocol allows the identification of coloured materials through the use in sequence of complementary techniques, so as to fully exploit the information given by each instrument. Preliminarily to the instrumental investigations on ancient books and miniatures is the compilation of spectroscopic databases obtained from \u201cstandard\u201d samples prepared on parchment, according to recipes described in medieval artistic treatises. The protocol starts with an extensive investigation with UV\u2013visible spectrophotometry in reflectance mode, collecting spectra from all the most significant painted areas in the manuscript; chemometric classification is then performed on the spectra to highlight areas possibly containing the same materials. The second step involves in-depth inspection of miniatures under optical microscopy that guides the interpretation of reflectance spectra. XRF spectrometry is then performed to characterise pigments and metal layers, to verify the presence of overlapping layers, to identify mordants in lakes and to recognise minor components that may yield information concerning provenance; in addition, chemometric classification can be performed on element concentrations to highlight similar areas. Finally, Raman spectroscopy is used to shed light on the uncertain cases, if still present. Such a procedure offers a wealth of information without causing stress to the manuscripts under analysis

Common and snow leopards share prey, but not habitats: competition avoidance by large predators?

Resource exploitation and behavioural interference underlie competition among carnivores. Competition is reduced by specializing on different prey and/or spatiotemporal separation, usually leading to different food habits. We predicted that two closely related species of large cats, the endangered snow leopard and the near-threatened common leopard, living in sympatry, would coexist through habitat separation and exploitation of different prey species. In central Himalaya, we assessed (2006–2010) habitat and diet overlap between these carnivores. The snow leopard used grassland and shrubland, whereas the common leopard selected forest. Contrary to our prediction, snow leopard and common leopard preyed upon similar wild (Himalayan tahr, musk deer) and domestic species (Bos spp., dogs). Dietary overlap between snow leopard and common leopard was 69% (yearly), 76% (colder months) and 60% (warmer months). Thus, habitat separation should be the result of other factors, most likely avoidance of interspecific aggression. Habitat separation may not always lead to the use of different prey. Avoidance of interspecific aggression, rather than exploitation of different resources, could allow the coexistence of potentially competing large predator

La spettroscopia di riflettanza UV-visibile con fibre ottiche: luci ed ombre nell'indagine di manoscritti illuminati

UV-visible spectroscopy in diffuse reflectance mode is a simple and fast technique that can be applied advantageously in the characterisation of pictorial artworks, above all in situations in which the range of pigments and dyes be limited by age, geographical zone and painting technique. It is particularly useful in application with optic fibres in the configuration known as FORS (Fibre Optic Reflectance Spectroscopy). Despite of some clear disadvantages, first of all relative difficulty in interpretation of spectra from mixtures and from dyes, FORS can be proposed as technique of preliminary investigation in the analysis of miniatures on manuscripts, a situation in which fastness of analysis and non invasivity are very important features