A study on Correggio wall paintings: characterization of technique and materials of Abbey Church of S. Giovanni Evangelista in Parma, Italy

This study deals the materials of the sub- arch of the Del Bono chapel of the Abbey Church of S. Giovanni Evangelista in Parma, Italy, datable around 1523. The author of the painting is Antonio Allegri, known as Correggio (1489 – 1534), considered one of the greatest painters of the sixteenth century. Optical microscopy, micro-Raman spectroscopy, micro-Fourier Transform Infrared spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and gas chromatography coupled with mass spectrometry were selected in order to provide the higher set of significant data, limiting as much as possible sampling. The analysis has allowed to identify the pigments, characteristic of the epoch. The Correggio’s palette is composed by mineral pigments, sometimes expensive such as lapis lazuli, azurite and cinnabar, together with a wide range of earths or by synthetic pigments like smalt blue. From the amino acid content determination through GC/MS it was shown that, for all samples examined, the protein fraction is to be attributed to the presence of a mixture of egg and animal glue, present as binders in the samples containing lazurite, smalt, hematite, green earth and goethite. This allows to assume the use of a secco technique, also with pigments that do not need the employment of organic binding media on wall. For the gilding sample the hypothesis is that Au foil had been applied on a brown background where the Au foil is applied on the oil-based missione

Raman modes in Pbca enstatite (Mg2Si2O6): an assignment by quantum mechanical calculation to interpret experimental results

Raman spectra of orthoenstatite have been computed from first principles, employing the hybrid Hamiltonian WC1LYP.[1] The calculated data show excellent agreement with the experimental data from literature with an absolute average difference of ~5 cm1. The quantum mechanical simulation allowed the assignment of Raman features to specific vibrational modes. This enabled to assess quantitatively the contributions of internal (tetrahedral stretching) and external (tetrahedral chains and M1 and M2 cations) vibrations. Moreover, the mass substitution of 56Fe for 24Mg in the M1 and M2 sites and of 30Si and 18O for the 28Si and 16O sites, pointed out the relative contributions of the cations to each mode within different sites. The description of the Raman modes enabled to relate the major experimental peaks to specific structural vibrations, and to link the changes in crystal structure to those modes with pressure, temperature and composition. The results provide new clues to identify most suitable peaks for the investigation of the intracrystalline ordering of Fe and Mg in the M1 and M2 sites, and of Al in the tetrahedral and octahedral sites. Moreover we have been able to identify those peaks which are related to structural features, like tetrahedral bond distances

Raman Analysis on 18th Century Painted Wooden Statues

A micro-Raman investigation on four wooden polychrome sculptures of Jan Geernaert (1704-1777), a Flemish sculptor who worked in Italy in the 18th century, is presented. The statues, representing the Holy Virgin Mary, with the infant Jesus in three of them, were created in the period 1750-1770 and are all made by poplar wood. The purpose of the micro-Raman investigations was to identify the original pigments used in 18th century, after later repainting interventions. In all statues, wood is covered by a groundwork, made by gypsum and animal glue. All pigments were identified, both in the original pictorial cover or in later repainted layers. Pigments were spread on a white lead layer (the so called imprimitura). Attention was particularly focused on the blue colours of the Holy Virgin mantle. In the external repainted layers, Prussian blue (Iron(II,III) hexacyanoferrate(II,III)) was found, together with ultramarine blue, a synthetic pigment, alternative to natural precious lapis lazuli, accessible on or after 1828. In one case, phthalocyanine blue is found, confirming a recent (later than 1930-35) restoration. The original skin colours are obtained by white lead and cinnabar (HgS), while the repainted layers are made by mixing chrome yellow (PbCrO4, synthesized in 1809), zinc yellow (ZnCrO4, 1809), red lead (Pb3O4), ultramarine blue, cinnabar, hematite (Fe2O3), goethite (-FeOOH), calcite (CaCO3) and white lead.Nous présentons une étude par micro-spectroscopie Raman sur la polychromie de quatre sculptures en bois de Jan Geernaert (1704-1777), sculpteur flamand qui a travaillé en Italie au 18ème siècle. Les statues, représentant la Sainte Vierge Marie, avec l'enfant Jésus pour trois d'entre elles, ont été réalisées entre 1750-1770 et sont toutes réalisées en peuplier. Le but de l’investigation par micro-spectroscopie Raman a été d'identifier les pigments d'origine et ceux issus des restaurations ultérieures. Pour toutes les statues, le bois est recouvert d’une couche de préparation réalisée par un mélange de gypse et de colle animale. Tous les pigments ont pu être identifiés, tant dans les couches picturales d'origine que sur les repeints plus tardifs. Les pigments ont été appliqués sur une couche de blanc de plomb (appelé imprimitura). Une attention particulière a été portée sur les couleurs bleus du manteau de la Sainte Vierge. Pour les couches externes correspondant aux repeints, nous avons identifié du bleu de Prusse (fer (II, III) hexacyanoferrate (II, III)) et de l'outremer, un pigment de synthèse disponible à partir de 1828 en alternative lapis-lazuli. Dans un cas, le bleu de phtalocyanine a été identifié, confirmant une restauration plus récente (post 1930-1935). La couleur d'origine de la peau est réalisée à partir de blanc de plomb et de cinabre (HgS). Les pigments présents dans les peintures plus récentes sont les suivants : jaune de chrome (PbCrO4 synthétisé en 1809), jaune de zinc (ZnCrO4, 1809), minium (Pb3O4), bleu outremer, cinabre, hématite (Fe2O3), goethite (-FeOOH), calcite (CaCO3) et blanc de plomb

Super-adsorbent polyacrylate under swelling in water for passive solar control of building envelope

Super-adsorbent polymers have the capacity to immobilize huge quantities of water in the form of hydrogel, thanks to their configuration. A commercial sodium polyacrylate (PA) was analysed as such and at different water uptakes, indicated through the weight ratios PA:H2O. The hydrogels were prepared using different type of water (tap, distilled and deuterated) and characterized by Infrared and Raman spectroscopic analyses, nuclear magnetic resonance experiments, CHN elemental analysis, measurements of thermal conductivity and diffusivity. All the measurements were done in order to assess applications of PA:H2O gels as Thermal Energy Storage systems for improving thermal performances of building envelope through passive solar walls. It has been observed that the behaviour of the hydrogels depends both on temperature and water content. In certain conditions such as low weight ratios, a spontaneous and quick cooling of the hydrogel could be observed. The curves of heat flow and average specific heat (cp) were determined as a function of temperature in order to investigate the states of water in PA hydrogels. When a few water molecules are present, they are mainly and strongly bonded with carboxylate groups. Increasing the amount of water, greater shells of solvation around ionic groups form and water molecules can even interact with neighbouring non-polar hydrocarbon groups. At very high amount of water molecules, they are much more involved into H-bonds among themselves, rather than with PA, so that water pools form into the links of polymeric network. Bulk-like water can freeze and melt. Whatever the amount of water in the hydrogel, its thermal capacity is higher than dry polymer, because the heat can be absorbed by the continuous desorption of water from polymer to bulk-like water (watergel → waterliquid), which can evaporate as temperature approaches 100 °C (watergel → waterliquid → watervapour)

Micro-Raman mapping of the polymorphs of serpentine

Serpentinites are rocks, often used in buildings, formed in large extent by minerals of the serpentine group: chrysotile, antigorite, lizardite, and polygonal serpentine. The fibrous type (e.g. chrysotile) of serpentine group minerals, along with several amphibole varieties (e.g. actinolite and tremolite), are the major components of asbestos family. The exposure to fine fibrous asbestos powder is linked to diseases such as pleural mesothelioma and asbestosis. The identification of the main varieties of the serpentine group, laminated or fibrous, becomes an issue of great interest for public health. This work introduces an analytical strategy able to distinguish the different serpentine polymorphs directly on the sample, allowing the analysiswithin their textural environment, evidencing at themicrometer scale the mineral reactions of the phases. Samples coming from the Koniambo massif (Grande Terre Island, New Caledonia) were studied by means of optical microscopy, scanning electron microscopy–energy dispersive X-ray spectroscopy, and Raman spectroscopy. Raman peaks observed in the high wavenumber spectral range of 3550–3850 cm-1, associated with OH stretching vibrations, allow the iscrimination of the all four serpentine varieties. The relationship between the different varieties of serpentine, at a micrometric scale, in complex samples, has been investigated by two-dimensional Raman mapping

Combining OCT and NMR-MOUSE techniques to study the stratigraphy of historical violins: the thickNESS project

In this work, Optical Coherence Tomography (OCT) and Nuclear Magnetic Resonance (NMR-MOUSE) have been applied to precious historical violins made by the most renowned makers of the Italian lutherie, such as Amati, Stradivari and Guarneri ‘del Gesù’, and hosted in the Museo del Violino in Cremona. Several large fragments removed during past restorations from instruments produced by the luthiers Stainer, Gasparo da Salò, Maggini and Guadagnini, as well as laboratory models simulating musical instruments stratigraphy, were further examined. OCT study was carried out with a prototype high-resolution portable SdOCT instrument providing layer thickness measurements and information about the presence of particles, cracks and delaminations. NMR analyses were performed with a Magritek Kea spectrometer and a Profile NMR-MOUSE (PM5) giving information on the wood density and elasticity, the last one possibly related to adopted treatments. The analyses have been conducted within the MOLAB Transnational Access - EU H2020 Project IPERION CH (thickNESS Project). Data interpretation is still in progress and promising results are expected to reveal in-depth insight into the finishing violin making process. These outcomes will be integrated with the results from UVIFL, FT-IR, Raman and XRF techniques in order to set up a methodology which allowed researchers to non-invasively characterize the stratigraphy of historical violins

Titanium dioxide nanoparticles promote arrhythmias via a direct interaction with rat cardiac tissue

BackgroundIn light of recent developments in nanotechnologies, interest is growing to better comprehend the interaction of nanoparticles with body tissues, in particular within the cardiovascular system. Attention has recently focused on the link between environmental pollution and cardiovascular diseases. Nanoparticles <50 nm in size are known to pass the alveolar¿pulmonary barrier, enter into bloodstream and induce inflammation, but the direct pathogenic mechanisms still need to be evaluated. We thus focused our attention on titanium dioxide (TiO2) nanoparticles, the most diffuse nanomaterial in polluted environments and one generally considered inert for the human body.MethodsWe conducted functional studies on isolated adult rat cardiomyocytes exposed acutely in vitro to TiO2 and on healthy rats administered a single dose of 2 mg/Kg TiO2 NPs via the trachea. Transmission electron microscopy was used to verify the actual presence of TiO2 nanoparticles within cardiac tissue, toxicological assays were used to assess lipid peroxidation and DNA tissue damage, and an in silico method was used to model the effect on action potential.ResultsVentricular myocytes exposed in vitro to TiO2 had significantly reduced action potential duration, impairment of sarcomere shortening and decreased stability of resting membrane potential. In vivo, a single intra-tracheal administration of saline solution containing TiO2 nanoparticles increased cardiac conduction velocity and tissue excitability, resulting in an enhanced propensity for inducible arrhythmias. Computational modeling of ventricular action potential indicated that a membrane leakage could account for the nanoparticle-induced effects measured on real cardiomyocytes.ConclusionsAcute exposure to TiO2 nanoparticles acutely alters cardiac excitability and increases the likelihood of arrhythmic events