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

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

Hidden colours in stuccowork damaged by fire: A multi-analytical investigation for revealing the original decorative pattern

The finishes applied on stuccoworks deserves in-depth analytical investigations. A complete chemical andmorphological survey is very useful in reconstructing the artist\u2019s technique, the history of the artworksthrough the sequence of the applied layers, and is needed as a basis for any conservation approach.Microscopic observations, both optical and electronic (SEM), and spectroscopic analyses (Raman, FTIRand EDS) of gilded and polychrome finishes on plaster relieves, were carried out on 17 samples from acelebrated neoclassical hall in the Royal Palace of Milan (Hall of Caryatids). The original decorative patternhad been damaged during a bomb-induced fire in the Second World War. Most of the surfaces have beenfatally compromised and blackened by the effects of the fire. The survey presented here analysed thematerials constituting the stucco surfaces and the damage induced by the fire. Green pigments wereindividuated and mapped, although no green surfaces were visible to the naked eye. It was thereforepossible to reconstruct a decorative pattern painted in green, gold and white, similar to traditions ofdecoration in Austria and southern Germany

Plagioclase composition by Raman spectroscopy

Plagioclase undergoes complex exsolution and ordering and phase transition processes during their evolution in nature, and this has hindered attempts to define simple trends relating the major peaks of their Raman spectra with composition. Here, the peak position and linewidth of major Raman features have been calibrated for a set of 20 plagioclases, spanning from albite to anorthite in composition, with symmetry and ordering states that were already well characterized. Point group symmetry is the most important factor determining the Raman peak behaviour with composition, though C math formula, I math formula, and P math formula plagioclases show different trends for the position of the main peak νa at ~500 cm−1. Using a simplifying approach, which merges the effect of Al–Si ordering and incommensurate modulations, a method has been developed to estimate the plagioclase composition from calibration of a few determinative Raman peaks. This makes use of the wavenumber difference Δab between the most intense peaks νa and νb around 500 cm−1, the linewidth Гa of the strongest νa peak, and the wavenumber difference Δcb between νc and νb peaks, where νc is a Raman feature at ~560–580 cm−1. The calibration was completed from data sets composed of spectra from metamorphic to pegmatitic plagioclase. The results were then tested against a further data set, mostly made by volcanic plagioclase. In most samples, the difference between electron micro probe analysis (EMPA) and Raman compositions is less than 5%. Higher residuals (beyond 10%) are observed for intermediate plagioclase, suggesting that some differences in Δab exist between volcanic and metamorphic plagioclase of intermediate compositions. The Raman compositional results for a plagioclase from Marsili submarine volcano agree with composition and zoning found from the analysis by laser ablation

Oxidative and pro-inflammatory effects of cobalt and titanium oxide nanoparticles on aortic and venous endothelial cells

Ultra-fine particles have recently been included among the risk factors for the development of endothelium inflammation and atherosclerosis, and cobalt (CoNPs) and titanium oxide nanoparticles (TiNPs) have attracted attention because of their wide range of applications. We investigated their toxicity profiles in two primary endothelial cell lines derived from human aorta (HAECs) and human umbilical vein (HUVECs) by comparing cell viability, oxidative stress, the expression of adhesion molecules and the release of chemokines during NP exposure. Both NPs were very rapidly internalised, and significantly increased adhesion molecule (ICAM-1, VCAM-1, E-selectin) mRNA and protein levels and the release of monocyte chemoattractant protein-1 (MCP-1) and interleukin 8 (IL-8). However, unlike the TiNPs, the CoNPs also induced time- and concentration-dependent metabolic impairment and oxidative stress without any evident signs of cell death or the induction of apoptosis. There were differences between the HAECs and HUVECs in terms of the extent of oxidative stress-related enzyme and vascular adhesion molecule expression, ROS production, and pro-inflammatory cytokine release despite the similar rate of NP internalisation, thus indicating endothelium heterogeneity in response to exogenous stimuli. Our data indicate that NPs can induce endothelial inflammatory responses via various pathways not involving oxidative stress

Raman spectroscopy as a PAT for pharmaceutical blending: advantages and disadvantages

Raman spectroscopy has been positively evaluated as a tool for the in-line and real-time monitoring of powder blending processes and it has been proved to be effective in the determination of the endpoint of the mixing, showing its potential role as process analytical technology (PAT). The aim of this study is to show advantages and disadvantages of Raman spectroscopy with respect to the most traditional HPLC analysis. The spectroscopic results, obtained directly on raw powders, sampled from a two-axis blender in real case conditions, were compared with the chromatographic data obtained on the same samples. The formulation blend used for the experiment consists of active pharmaceutical ingredient (API, concentrations 6.0% and 0.5%), lactose and magnesium stearate (as excipients). The first step of the monitoring process was selecting the appropriate wavenumber region where the Raman signal of API is maximal and interference from the spectral features of excipients is minimal. Blend profiles were created by plotting the area ratios of the Raman peak of API (AAPI) at 1598 cm-1 and the Raman bands of excipients (AEXC), in the spectral range between 1560 and 1630 cm-1, as a function of mixing time: the API content can be considered homogeneous when the time-dependent dispersion of the area ratio is minimized. In order to achieve a representative sampling with Raman spectroscopy, each sample was mapped in a motorized XY stage by a defocused laser beam of a micro-Raman apparatus. Good correlation between the two techniques has been found only for the composition at 6.0% (w/w). However, standard deviation analysis, applied to both HPLC and Raman data, showed that Raman results are more substantial than HPLC ones, since Raman spectroscopy enables generating data rich blend profiles. In addition, the relative standard deviation calculated from a single map (30 points) turned out to be representative of the degree of homogeneity for that blend time