Improved photocatalytic properties of doped titanium-based nanometric oxides

Photocatalysis is considered one of the most promising technologies for applications in the environmental field especially in the abatement of water-soluble organic pollutants. In this field, titanium dioxide nanoparticles have drawn much attention recently; however, the use of this oxide presents some limitation since it allows to obtain high photoresponse and degradation efficiency only under UV light irradiation, that represents the 3 to 4% of the solar radiation, so preventing its environmental large-scale applications under diffuse daylight. In this work the photocatalytic efficiencyoftitanium-based oxides systems containing alkaline earth metals such as barium and strontium, prepared by a simple sol-gel method was investigated, evaluating the degradation of methylene blue as model compound under UV and visible light irradiation. The results were compared with those obtained with Degussa P25 titanium dioxide. The achieved degradation percentage of methylene blue are very promising showing that under visible light irradiation it is possible to obtain a maximum dye removal percentage ~ 50 % higher than that obtained with the Degussa P25

Waterborne Acrylate-Based Hybrid Coatings with Enhanced Resistance Properties on Stone Surfaces

The application of coating polymers to building materials is a simple and cheap way to preserve and protect surfaces from weathering phenomena. Due to its environmentally friendly character, waterborne coating is the most popular type of coating, and improving its performance is an important key of research. The study presents the results regarding the mechanical and photo-oxidation resistance of some water-based acrylic coatings containing SiO2 nanoparticles obtained by batch miniemulsion polymerization. Coating materials have been characterized in terms of hydrophobic/hydrophilic behavior, mechanical resistance and surface morphology by means of water-contact angle, and scrub resistance and atomic force microscopy (AFM) measurements depending on silica-nanoparticle content. Moreover, accelerated weathering tests were performed to estimate the photo-oxidation resistance of the coatings. The chemical and color changes were assessed by Fourier-transform infrared spectroscopy (FTIR) and colorimetric measurements. Furthermore, the nanofilled coatings were applied on two different calcareous lithotypes (Lecce stone and Carrara Marble). Its properties, such as capillary water absorption and color modification, before and after accelerated aging tests, were assessed. The properties acquired by the addition of silica nanoparticles in the acrylic matrix can ensure good protection against weathering of stone-based materials

MULTISPECTRAL IMAGING OF PAINTINGS. Potentialities and Limitations of the technique in relation with the chemical and optical properties of the pictorial materials

This thesis focuses on the application of multispectral images for the analysis of pictorial materials in comparison with the traditional UV-fluorescence photography and infrared reflectography. The assessment of multispectral imaging for the study of pictorial materials was supported by other analytical techniques such as reflectance and fluorescence spectroscopy, X-Ray Fluorescence (XRF), UV-visible absorption spectroscopy and Total Attenuated Reflectance - Fourier Transform Infrared Spectroscopy (ATR-FTIR). The multispectral imaging was tested on swatches of pictorial layers (constituted by ancient and modern pigments), binders (egg and linseed oil) and natural varnishes. For the organic materials, accelerated ageing methods (photo-chemical and thermal degradation) were used to model the optical and chemical changes occurring during the lifetime of a painting. In addition, a diagnostic investigation was performed on two paintings placed in "Accademia di San Luca" (Rome) by means of UV-fluorescence photography, radiography, reflectance spectroscopy, X-ray fluorescence spectroscopy, UV-VIS-NIR multispectral imaging. Multispectral images, comparing to traditional techniques, permit to individuate specific spectral behaviors, and, in some cases, to identify the pigment and/or non-homogeneous areas of the pictorial or varnish layers. The possibility to select some infrared wavelengths allows to see details of the preparatory layers, leading to a more accurate analysis of the technique of execution. However, the limitations of multispectral images for the identification of complex mixtures and/or different layers of materials depending on the type of filter used

Imagerie multispectrale en peinture artistique : Potentialités et limites de la technique en relation avec les propriétés chimiques et optiques des matériaux picturaux

This thesis focus on the application of multispectral images for the analysis of pictorial materials in comparison with the traditional UV-fluorescence photography and infrared reflectography. The assessment of multispectral imaging for the study of pictorial materials was supported by other analytical techniques such as reflectance and fluorescence spectroscopy, X-Ray Fluorescence (XRF), UV-visible absorption spectroscopy and Total Attenuated Reflectance - Fourier Transform Infrared Spectroscopy (ATR-FTIR). The multispectral imaging was tested on swatches of pictorial layers (constituted by ancient and modern pigment), binders (egg and linseed oil) and natural varnishes. For the organic materials, accelerated ageing methods (photo-chemical and thermal degradation) were used to model the optical and chemical changes occurring during the lifetime of a painting. In addition, a diagnostic investigation was performed on two paintings placed in "Accademia di San Luca" (Rome) by means of UV-fluorescence photography, radiography, reflectance spectroscopy, X-ray fluorescence spectroscopy, UV-VIS-NIR multispectral imaging. Multispectral images, comparing to traditional techniques, permit to individuate specific spectral behaviors, and, in some cases, identify the pigment and/or non-homogeneous areas of the pictorial or varnish layers. The possibility to select some infrared wavelengths allows to see details of the preparatory layers, leading to a more accurate analysis of the technique of execution. However, the limitations of multispectral images for the identification of complex mixtures and/or different layers of materials depending on the type of filter used.Cette thèse porte sur l’application des images multispectrales pour l’analyse des matériaux utilisés dans une peinture par comparaison avec la photographie traditionnelle de fluorescence induite par rayons UV et la réflectoraphgie infrarouge. L’application des images multispectrales à l'étude des matériaux picturaux a été appuyée par d'autres techniques analytiques telles que la spectroscopie de réflectance et de fluorescence, la spectroscopie de fluorescence X, la spectroscopie d'absorption UV-visible et la spectroscopie infrarouge transformée de Fourier en réflectance totale atténuée. L’imagerie multispectrale a été testée comme outil de laboratoire d’identification des matériaux picturaux. Ainsi, des couches de peinture constituées de pigments (anciens et modernes), de liants (œufs et l’huile de lin) et de vernis naturels ont été analysées. Pour les matériaux organiques, des expériences de vieillissement accéléré (photodégradation et dégradation thermique) ont permis de modéliser les changements optiques et chimiques intervenant au cours de la vie d’un tableau. De plus, une analyse diagnostique a été réalisée sur deux tableaux conservés à « Accademia di San Luca » (Rome) par photographie de fluorescence induite par rayonnement UV, radiographie, spectroscopie de réflectance, spectroscopie de fluorescence X, images de fluorescence UV et réflectance multispectrale, réflectographie infrarouge multispectrale. Par rapport aux techniques traditionnelles, les images multispectrales permettent d’analyser de nombreuses régions spectrales qui, dans certains cas, permettent d’identifier le pigment et/ou des zones non homogènes de la couche superficielle picturale. Certaines gammes de longueurs d’onde infrarouge permettent notamment de voir les détails des différentes couches préparatoires, amenant à une analyse plus précise de la technique d’exécution. Cependant, une des limites des images multispectrales concerne l’identification des mélanges complexes et/ou des différentes strates de matériaux en fonction du type de filtre utilisé

Post-Processing of VIS, NIR, and SWIR Multispectral Images of Paintings. New Discovery on the The Drunkenness of Noah, Painted by Andrea Sacchi, Stored at Palazzo Chigi (Ariccia, Rome)

IR Reflectography applied to the identification of hidden details of paintings is extremely useful for authentication purposes and for revealing technical hidden features. Recently, multispectral imaging has replaced traditional imaging techniques thanks to the possibility to select specific spectral ranges bringing out interesting details of the paintings. VIS–NIR–SWIR images of one of the The Drunkenness of Noah versions painted by Andrea Sacchi, acquired with a modified reflex and InGaAs cameras, are presented in this research. Starting from multispectral images we performed post-processing analysis, using visible and infrared false-color images and principal component analysis (PCA) in order to highlight pentimenti and underdrawings. Radiography was performed in some areas to better investigate the inner pictorial layers. This study represents the first published scientific investigation of The Drunkenness of Noah’s artistic production, painted by Andrea Sacchi

Sano di Pietro and his workshop: the materials and techniques of manuscript illumination

The artist’s workshop phenomenon formed the foundation for the artistic production in the Italian Renaissance. From this background emerged the figure of Sano di Pietro, a popular and highly prolific Sienese painter and illuminator (1406 – 1481). In this work we will present new results from a multi-analytical investigation of the illuminated manuscript Cors. 41.A.1 stored in the Library of Accademia Nazionale dei Lincei e Corsiniana of Rome. The attribution of illuminations to Sano di Pietro’s workshop is uncertain. For this reason, we have carefully analysed pigments, inks and the parchment used for illuminating and writing, aiming at identifying the palette and the artistic technique used. The experimental setup consists in the analysis of materials through non-destructive methods, i.e. Energy Dispersive X-ray Fluorescence (EDXRF), Fiber Optics Reflectance Spectroscopy (FORS) and multispectral imaging. The analytical results of MS. Cors. 41.A.1 were compared with those of MSS. 196 and 198 of the Fitzwilliam Museum of Cambridge attributed to Sano di Pietro. The study examines how Sano di Pietro’s workshop may have operated and provides information about artistic collaboration. We could determine what pigments the master and his collaborators employed and finally describe the relationship between artists and patrons

Identification of pictorial materials by means of optimized multispectral reflectance image processing

Image spectroscopy may allow identifying the materials present on a painting surface in a non-invasive way. The proposed method aims at optimizing, and thus reducing, the number of filters employed, while still providing a robust method, that achieves similar performances as traditional ones, which in turn employ a large number of filters. Moreover, we targeted the identification of the pigments present on the outer layer of a painting independently from their thickness, the underlying background or support, the binder employed, their aging and acquisition set-up. In order to achieve this objective, a relevant number of swatches have been prepared, on different supports and with different thicknesses and binding mediums. Spectral reflectance curves of such chemically known pictorial layers have been recorded by means of a spectrometer and a spectrophotometer. A novel Principal Component Analysis (PCA) based approach has been devised to select the most relevant wavebands, i.e. those that allow the most effective discrimination among (quasi)metameric colours, which are thus not to be distinguished with the naked eye or with an RGB camera. Comparisons of results using the 13 filters available on the filter wheel and of a selection of only 3 and 4 filters, support the idea of the simplified version investigated in this paper being a viable alternativ

New Frontiers in the Digital Restoration of Hidden Texts in Manuscripts: A Review of the Technical Approaches

The digital restoration of historical manuscripts centers on deciphering hidden writings, made imperceptible to the naked eye due to factors such as erasure, fading, carbonization, and aging effects. Recent advancements in modern technologies have significantly improved our ability to unveil and interpret such written cultural heritage that, for centuries, had remained inaccessible to contemporary understanding. This paper aims to present a critical overview of state-of-the-art technologies, engaging in discussions about perspectives and limitations, and anticipating future applications. Serving as a practical guide, this work seeks to assist in the selection of techniques for digitally restoring ancient writings. Additionally, potential and challenges associated with integrating these techniques with advanced machine-learning approaches are also outlined

Multispectral reflectance and UV fluorescence microscopy to study painting’s cross sections

UV Fluorescence microscopy is a powerful mean for visualizing and identifying structures in a specimen, and it has long been used in many applications, including pigment identification in artworks.Typical painting cross section samples are the result ofmultiple layers and especially for paintings produced from thethirteen to sixteencenturies, it is possible that for different pigments a different binder has been used, resulting in a complex stratificationof materials.In this paper we propose a novel multispectral microscopy imaging system, which is specially designed for cultural heritage application, capable of acquiring both reflectance and fluorescence imagesin different wavebands, so to be able to document UV fluorescence emission and reflectance spectra