Sustainable knowledge and preservation of Cultural Heritage for future generations (2-4 May + Museum visit on Wed. morning May 4)

Resume : Restorers of historical/artistic stone based artifacts, are frequently faced with problems caused by biofilms inhabiting outdoor stone surfaces. Apart from esthetic damages, important deterioration phenomena related to the physico-chemical transformation of the mineral substrate occur and require continuous, high cost, maintenance, mainly consisting of periodical cleaning treatments. A multidisciplinary approach is needed to address the issue of biofilm formation since the remedy should afford both conservation properties and a marked improvement in biological attack prevention. So far, from one hand, microbiologists are developing model systems of sub-aerial biofilms in order to understand their physiology, activity and complex interactions with stone substrate [1]; from the other hand, material scientists are designing and developing innovative and eco-sustainable materials able to exert a long-lasting biocide activity, inert and respectful to stone of work of art substrates. In our lab nanostructured materials prepared by dispersion of metal and oxide nanoparticles in polysiloxanes based, water repellent/reinforcing matrices have been developed and tested, both in vitro and in situ [2-3]. In the latter case, a high-throughput investigation of the diversity of microbial communities was also performed by DNA sequencing [4]. The obtained information may contribute to plan effective strategies for a correct restoration and conservation. [1] F. Villa, B. Pitts, E. Lauchnor, F. Cappitelli, P.S. Stewart, Front. Microbiol., 6 (2015) 1251 [2] N. Ditaranto, I.D. van der Werf, R.A. Picca, M.C. Sportelli, L.C. Giannossa, E. Bonerba, G. Tantillo, Luigia Sabbatini, New J. Chem., 39 (2015) 6836 [3] I.D. van der Werf, N. Ditaranto, R.A. Picca, M.C. Sportelli, L. Sabbatini, Herit. Sci., 3:29 (2015) 1 [4] G. Chimienti, R. Piredda, G. Pepe, I.D. van der Werf, L. Sabbatini, C. Crecchio, P. Ricciuti, A. D'Erchia, C. Manzari, G.Pesole, Plos One, (2016) submitted

Resume : Laser cleaning of lichenic thalli on Cultural Heritage stones has been investigated with successful results on carbonated rocks, e.g. dolostone [1, 2]. However, for granite, only a study has found [3], so further research on this topic is needed in order to identify the influences of the rock properties and also of the type of lichen on the process. The aim of the present paper leads to the evaluation of laser cleaning of two crustose species of lichen Pertusaria amara and Pertusaria pseudocorallina colonizing a granite from NW Spain commonly used in the Cultural heritage. The effectiveness of a laser cleaning using a Nd:YVO4 laser at 355 nm was compared with that obtained by a conventional mechanical cleaning (scalpel) and the combination of both, scalpel followed by laser. Lichen extraction rate and damage in each rock forming minerals after the cleanings were evaluated by means of optical microscopy, SEM-EDS, FTIR and hyperspectral imaging technique. It was found that the effectiveness of the laser cleaning differed for each lichen specie to be cleaned, being the colour of the thalli the characteristic that seemed to determine this difference. None of the tested procedures achieved a complete lichen thalli extraction due to the high penetration of the lichen structures through the fissures; nevertheless, among all the procedures, the combination between scalpel and laser obtained the best results. Keywords: stone conservation, laser, scalpel, lichen, granite, biodeterioration, cleaning. REFERENCES: 1. Sanz M., Oujja M., Ascaso C., de los Ríos A., Pérez-Ortega S., Souza-Egipsy V., Wierzchos J., Speranza M., Vega Cañamares M., Castillejo M. Applied Surface Science 346 (2015) 248–255. 2. Speranza M., Sanz M., Oujja M., de los Rios A., Wierzchos J., Pérez-Ortega S., Castillejo M., Ascaso C. International Biodeterioration & Biodegradation 84 (2013) 281-290. 3. Pozo-Antonio J.S., Fiorucci M.P., Rivas T., López A.J., Ramil A., Barral D. Suitability of hyperspectral technique to evaluate the effectiveness of the cleaning of liquenic colonization with a 355 nm Nd:YVO4 nanosecond laser. EMRS2015 Spring Meeting 2015.

Resume : Atmospheric pollution (gas and partcles) is the main responsible for marbles deterioration. Traditionally polymeric resins, acrylic and vinyl polymers, organosilicone compounds and fluorinated film forming agents have been applied to stone monuments as protective hydrophobic coatings against deterioration. In the last few years, nanomaterials (nano-oxides) have been frequently applied for restoration and conservation of works of art. Hybrid coatings have been realized using nanoparticles (oxides) mixed with commercial resins leading to superhydrophobic properties. In order to evaluate the stability of the applied coatings towards degradation induced by solar radiation and interaction with the atmospheric pollution, exposure tests to a typical polluted urban environment (Milan) have been carried out. The efficiency of the coatings has been evaluated through an integrated approach based on the use of different techniques including contact angle measurements, water vapor permeability, atomic force microscopy and colorimetric analysis. Ion chromatography has been employed to evaluate salts formation induced by the interaction of the marbles surface with atmospheric pollution.

Resume : The consequences of the photodegradation of celluloid on the modification of the material properties have been analysed. Various techniques were used to follow the accelerated degradation provoked by exposure to light (wavelengths > 300 nm) in the presence of oxygen. The objective was to relate the modification of the properties at various levels of investigation, from the molecular properties towards the degradation of the macroscopic properties. The modification of the chemical structure was followed by infrared and UV-visible spectroscopic analyses. Gloss and colour measurements were performed, as well as characterization of surface mechanical properties by micro-hardness and Atomic Force Microscopy (AFM). The results showed that the loss of gloss and the decrease of the mechanical properties was a result of a combination of the progressive loss of plasticizer and chain-scission reactions. These developments were explained in light of the modifications of the chemical structure. Quantitative cross correlations of the degradation chemistry with performance-critical physical properties were established. Acknowledgments : The authors would like to thank the “Mission à la Recherche” of “Ministère de la Culture et de la Communication” for financial support.

Resume : Computational modelling can be regarded as the perfect “portable and non-invasive” technique in Cultural Heritage Conservation. Here I shall present how computational chemistry can complement experimental investigations by establishing structure-property relations of the artwork components and individuating degradation pathways. As an example, Chrome Yellows (CY) are a family of synthetic pigments of formula PbCr(1-x)SxO4, used by van Gogh and other nineteenth-century masters, whose photo-degradation threatens the conservation of invaluable works of art. Experimental studies have demonstrated that the darkening of the pigment is provoked by the formation of superficial layers of Cr(III) oxides due to the reduction of the Cr(VI) to the Cr(III). A strong correlation between CY degradation and its chemical composition (sulfate richness) and structure (orthorhombic vs. monoclinic) was also experimentally put forward. CY pigment and its sulphate-substituted compounds have been investigated by DFT calculations. We have taken into account well defined models, PbCr(1-x)SxO4 (x=0, 0.25, 0.5, 0.75, 1), representative of a possible sulfate pathway to CY degradation and have investigated the interplay between structural and electronic properties as a function of the composition and the crystalline phase. References S. Fantacci, A. Amat; A. Sgamelloti Acc. Chem. Res. 2010, 43, 802 . I. Cianchetta, I. Colantoni, F. Talarico, F. d'Acapito, A. Trapananti, C. Maurizio, S. Fantacci, I. Davoli J. Anal. At. Spectrom. 2012, 27, 1941. A. Amat, C. Miliani, A. Romani, S. Fantacci Phys. Chem. Chem. Phys. 2015, 17, 6374.

Resume : Weathering steels or high strength low alloy steels are a group of steels with the unique characteristic that as they corrode under proper conditions, they form a dense and tightly adherent oxide barrier that seals out the atmosphere and retards further corrosion. Due to their rustic antique appearance, weathering steels are extensively used for artistic and architectural purposes in outdoor sculptures, as exterior buildings facades. In this study an situ investigation of the atmospheric corrosion phenomena affecting a weathering steel urban building has been performed by means of a non-destructive approach based on electrochemical impedance spectroscopy (EIS). EIS measurements, generally performed to investigate the protecting properties of organic coatings, can be also satisfactory employed for the in situ assessment of the conservation state of outdoor metallic cultural heritage assets, with the final aim of studying the corrosion mechanisms occurring on the metallic surface, measuring the corrosion rate and developing long-lasting and sustainable management and preservation strategies. In particular, the EIS measuring campaign has been performed on the COR-TEN load-bearing structure of a residential building, know as 25-Green, a treehouse designed by the architect Luciano Pia and located in Torino (Italy). The EIS measurements have been performed using a commercially available electrochemical interface and some specifically designed measuring probes realised by a 3D printer. The measurements have been performed in Na2SO4 0.1M solution, in the frequency range of 0.01 mHz to 100kHz, by stimulating the sample with a small alternating voltage, in the range 10 - 100 mV, while compensating the open corrosion potential (EOCP). The EIS results evidenced the different corrosion behaviour of the weathering steel structures correlated with the different production and lamination processes.

Resume : The use of vibration-based Structural Health Monitoring (SHM) to timely assess the occurrence of a damage in monumental structures has received a significant interest in recent years. However, successful field applications to architectural heritage constructions are still quite rarely documented, due to the complexity of their behaviour and to the low levels of vibration in operational conditions that typically characterize massive historical structures. The paper discusses recent applications and perspectives of SHM systems for seismic resilience of historical constructions, with specific reference to a couple of permanent dynamic monitoring systems recently installed by the authors on a monumental masonry bell-tower and on a monumental dome in Italy. The systems consist of high-sensitivity accelerometers and temperature sensors, whereby a fully automated modal identification and modal tracking procedure, coupled with multivariate statistical analysis techniques, allow a prompt and automated detection of small damages caused by low return period earthquakes. Non linear dynamic analyses under earthquake loading, based on tuned numerical models, are used to identify typical damage patterns and the associated values of the peak ground acceleration (PGA), as well as to assess the minimum detectable damage severity. The results provide evidence of the enhanced seismic resilience that can be achieved by preventive conservation and cost-effective maintenance enabled by SHM.

Resume : Vulnerability assessment is a very useful tool to identify, evaluate and prioritize the restoration of cultural heritage to stablish the preventive conservation policies. The degradation of monuments could be due to the effects caused by different scenarios and factors: structural damages, weathering affection, pollution agents, anthropogenic factors,… The conservation degree of each monument is the vulnerability, and its index is an indirect function of the level of deterioration. RIVUPH and ART-RISK are Spanish projects based on the analysis of environmental risk in historical cities and models to assess vulnerability. With this purpose two different approach are been evaluated: DELPHI method and FUZZY Logic, both tools based on the opinion of experts. The vulnerability analysis of four churches from Seville (Spain), have been studied to assess the monuments conservation degree. These models (DELPHY and FUZZY) are able to forecast the necessities of restoration overlapping different scenarios. ACKNOWLEDGMENT This Project has been carried out thanks to the funds of the Junta of Andalusia Project RIVUPH (HUM 6775) and the Ministerio de Economía y Competitividad Project ART-RISK.

Resume : RIVUPH and ART-RISK are Spanish projects based on the development of new tools for conservation strategies and policies. With this purpose vulnerability of buildings has been studied with different techniques. The vulnerability analysis depends on monuments conservation degree, the vulnerability index (VI %) was calculated, based on a vulnerability matrix (VM) which is also based on intrinsic variables and life of monuments that depend on the weathering forms, their evaluation and their extension. The weathering forms evaluation can be studied, according to risk assessment. This methodology has been compared with weathering maps, carried out by digital image analysis, CAD, 3D-documentation, LIF-2D maps or UAVS application with IR and cameras. These techniques have been applied to different monuments studied in Andalusia in order to understand the advantages and disadvantages for the surveillance and monitoring of vulnerability. The combination of these methods of monitoring allows quantifying the vulnerability of cultural heritage monuments, and it is a very useful tool to evaluate and prioritize the restoration budgets of a city or a region and to forecast the preventive conservation. ACKNOWLEDGMENT This Project has been carried out thanks to the funds of the Junta of Andalusia Project RIVUPH (HUM 6775) and the Ministerio de Economía y Competitividad Project ART-RISK.

Resume : Climate change impacts are functioning as risk multipliersto problems which are already apparent and affect cultural heritage sites. Sea Level Riseand increased storm events can damage structures that were not designed to withstand prolonged structural pressure, erosion, and immersion. Risks affecting coastal cultural heritage may stem from exposure to one or more hazards and it is important to facilitate a holistic understanding of factors driving them. This demands that the relation of cultural heritage’sphysical vulnerability resulting from social, economic and “development”processes, is understood. Risk is defined as “the probability of harmful consequences, resulting from the interaction between vulnerability and exposure”. However, vulnerability is not only a “product” but a “process” as well governedby various factors, which eventually drive its change over time. Therefore, an assessmentof vulnerabilityvariation in timeis needed. A comprehensive understanding of risks willbuild a basis for taking proactive rather than reactive measures to control vulnerability processes and reduce the anticipated risks in the future, in an innovative paradigm for conservation. In this study an initial risk assessment analysis related to increasing sea level and storm frequency for the Venetian Coastal Walls of Heraklion is presented. As proactive measures the use of laser diagnostic tools and smart materials are considered.

Resume : Preservation of cultural heritage artefacts involves increasingly laser techniques for e.g. cleaning and also diagnostics. Particulate removal from fibrous, polymer or painted substrates has been studied systematically [1,2]. Fundamental investigations combining e.g. laser pulse interactions with atomic force measurements lead to thermomechanical models [3]. Stratigraphy on the other hand is an indispensable technique in the preservation praxis. A laser-induced breakdown spectroscopy stratigraphy is been developed allowing depth profiling down to single micrometre ranges [4]. [1] S. Arif, W. Kautek, Studies in Conservation 60 (2015) S97-S105 [2] J. Colson, J. Nimmrichter, W. Kautek, Appl. Surf. Sci. 302 (2014) 314-317. [3] S. Arif, O. Armbruster, W. Kautek, Appl. Phys. A 111 (2013) 539-548. [4] T. Nagy, U. Pacher, H. Pöhl, W. Kautek, Appl. Surf. Sci. 302 (2014) 189-193.

Resume : The suitability of hyperspectral imaging technique as a non-invasive tool to determine the cleaning evaluation in granite was demonstrated in previous works [Pozo-Antonio et al., 2015a, b]. However, the obtained results showed that the surface roughness has an important influence in the reflectivity values along the studied range wavelength. This paper aims to provide a deep analysis of the influence of the surface roughness of two granites, with different grain sizes, in the reflectivity spectrum. Five of the most common available type of commercial finishes for granite (polished, honed, disc cutting, bushammering and flamed) were tested. Moreover, surfaces subjected to mechanical and laser cleaning procedures were also used in order to study the influence of each procedure in the resulted surface roughness and in the achieved reflectivity values. The appearance of the surfaces was characterized with SEM and the roughness parameters were measured with confocal microscopy, while the reflectivity values were computed with the hyperspectral imaging. This article contribute to provide a standardized information of characterizing the granite finishes that will be useful for the field of conservation of cultural heritage. Keywords: stone conservation, reflectivity, hyperspectral imaging, surface roughness, granite, stone cleaning. REFERENCES: Pozo-Antonio, J.S., Fiorucci, M.P. Ramil, A., López-Díaz, AJ., Rivas, T. Evaluation of the effectiveness of laser crust removal on granites by means of hyperspectral imaging techniques. Applied Surface Science 347, 2015a, 832–838. Pozo, S., Ramil, A., López, A.J., Fiorucci, M. P., Rivas, T. Evaluation by multispectral techniques of the laser cleaning progress: application to the removal of graffiti in granites. TECHNART2015, Catania, 2015b.

Resume : Glazed ceramic tiles (“azulejos” in Portuguese) configure an archetypal case of extensive application of ceramics in architectural cultural heritage. Of widespread traditional usage they are found covering the interior walls as well as external façades of churches and palaces, but also in decorative panels on walls, gardens and public buildings. Non-destructive characterization approaches are of utmost importance for the understanding of materials used and manufacture techniques for a better conservation and restoration methodology in order to maintain cultural valued materials for future generations as well as evaluating environmental impacts on historical artefacts. An overview will be presented on work performed using laboratory techniques that include X-ray Diffraction, X-ray Fluorescence, Variable Pressure Scanning Electron Microscopy, Optical Microscopy and Raman spectroscopy but also the use of Synchrotron Radiation absorption spectroscopies (XANES and EXAFS) through the access to large scale installation facilities such as the European Synchrotron Radiation Facility. As objects of study examples from 16th to 19th century Portuguese glazed blue and white and polychrome tiles of different origins will be presented from S. Salvador church in Coimbra, the National Tile Museum and Sintra National Palace, providing an insight to possible assessment approaches for this type of materials.

Resume : The São Domingos mine, is located in the Southeast part of Portugal within the Iberian Pyrite Belt (IPB; considered one of the oldest and important mining regions in Europe), with historical mining dating back from Roman times. More recently, the São Domingos deposit was mined between 1857 and 1966 for pyrite, copper and sulphur production. The significant geological and mining heritage is promoted in the context of the thematic tourism IPB Pyrite Route, based in local trails supported by information boards placed throughout the key points in the mine area as a sustainable development of the geo-mining tourism. Nowadays, intense acid mine drainage occurs, associated with large areas covered by mine wastes that were mapped with hyperspectral images aiming to assess the degree of contamination, based in mineralogical associations, in order to remediate or isolate the most dangerous areas. The waste materials characterization was performed and relevant contents of Se (>900 ppm) and Re (>3 ppm) were found in waste piles (ashes from roasted Cu-rich pyrite ore, finely milled pyrite ore and host rock waste) located at old sulphur factories. The results of a subsequent X-ray absorption spectroscopy study at the European Synchrotron Research Facility to assess the speciation state of Se and Re plus the nature of carrier phases(s) are presented as a contribution to a future sustainable recovery of valuable elements and to the preservation of the site by the removal of mine wastes.

Resume : The issue of conservation of the monumental heritage is mainly related to atmospheric pollution that causes the degradation of stone surfaces. Black crusts can be formed as a result of different kind of chemical and physical reactions between the stone surface and environmental factors (such as gaseous pollutants and aerosol particulate matter). These black layers present on the stone monuments reflect the composition of the aerosol particulate matter (PM) to which the surfaces are exposed. In particular elemental carbon (EC, also known as black carbon, typically emitted by combustion processes) is the PM component responsible for the characteristic black colour of the crusts where it is embedded together with calcium sulphate due to the conversion of calcium carbonate, the main constituent of the stone. The other PM component that is involved in the black layer formation is represented by the organic carbon (OC) which is emitted by numerous sources (traffic, heating plants, biomass burning, etc.). OC/EC in PM samples (quartz filters where the aerosol particulate matter has been homogeneously collected) are generally quantified by a reference method (TOT, Thermal Optical Transmittance) not suitable for the analysis of these components in the crusts. A new approach for OC/EC quantification, based on a simple thermal protocol, has been here proposed. The method validation has been performed analysing suitable reference standard prepared by mixing different chemical species in order to simulate the composition of the black crusts present on the monument surfaces.

Resume : Some pigments used for the decoration of Italian Renaissance lustred majolicas have been characterized by using different analytical approaches. By means of SEM-EDX analyses the main elements responsible for the colours have been highlighted. The blue decorations have been obtained by using a pigment containing cobalt which is mainly present in tetrahedral configuration as evidenced by XANES measurements (even if some differences in the configuration have been highlighted depending on the sample). Orange was generally obtained by means of lead antimonate, as evidenced by SEM-EDX. By meand of EXAFS and XANES measurements the presence of this chemical specie has been confirmed and it has been also highlighted that it often is present together with lead oxide and (PbCO3)2 • Pb(OH)2. The slight differences between the chemical composition of the various samples could be attributed to the use of slightly different recipes.

Resume : Laser cleaning is an attested method to clean surfaces. It is a selective and precise procedure and it is considered a safe technique for the conservators/restorers and for the environment. For these reasons, the use of laser cleaning on cultural heritage has been grown in the last decades. Setting the parameters conveniently, it is possible to remove the corrosion products respecting the original surfaces: selectivity and precision make laser cleaning an important instrument for cultural heritage safeguard. Unfortunately the interaction among laser parameters and corrosion products it is not yet clear. The aim of this study is to optimise tailored laser cleaning procedures for archaeological metals artefacts and to evaluate its real feasibility as a standard conservation procedure. With the purpose of doing this, the research analyses the combination and the interaction of different parameters and different work modalities to remove dangerous corrosion encrustations without affecting both the protective patina and the metallic surface. A Q-switched Yb:YAG fiber laser has been used on a set of artificially-aged Cu-based reference samples and on some real ancient bronze coins. Several irradiance, scanning speed and repetition rate values have been evaluated to optimise a possible standard procedure. XRD and SEM-EDS analyses have been performed in order to detect the chemical composition of the corrosion products and to assess the substrate and the corrosion products ablation thresholds. This allowed to perform a focused analysis and cleaning procedure. From the experimental findings, it seems clear that the number of passes and the irradiance values used have a key role in removing chlorides and other surface contaminants without affecting the original protective patina. It is possible to conclude that laser cleaning is a powerful technique due to its characteristics of selectivity and precision: it improves the legibility of the bronze artefact surface and, as a consequence, the knowledge of the artefact itself. Nevertheless, more studies are needed in order to verify the set parameters on other type of materials and artefacts.

Resume : LIF scanning technique combined with image analysis are suitable to obtain mapping of fluorescent species on the outermost layers of painted surfaces. Modern consolidants, constitued by vinylic and acrilic compounds, together with some historical binders (organic glues, casein, linseed oil) and a few organic pigments (e.g. lacquers) belong to the large group of fluorescent materials used on painted surfaces. Painted surfaces on wood and wooden pastes where study to map consolidants added during former not fully documented restorations. Laser induced fluorescence images were obtained by a ENEA LIF prototype at ≈5 m, the system was set up to detect the signature of pigments and consolidants at 266nm, while receiving detector was acquiring the full spectrum from 200nm to 850nm with a spectral resolution of 2.5nm. The spectroscopic detection system was spectrally calibrated, while radiometric calibration was not performed. The most relevant spectral features are identified by Principal Component (PC) analysis. Although the PCs do not possess any direct physical meaning, they can conveniently be described in terms of bands; since the LIF spectra result from linear combination of PC with appropriate weights (scores), the presence of bands in PC may have a close correspondence on actual emission bands. All identified features have been mapped along the scanned surfaces. This non destructive study has shown: a)retouches at 377nm, related to previous documented restoration with acrylic compounds,b)protection on gilded borders, restored by bold and mica powder,c)application of two different restoration products or varnishes, and d)retouches by Titanium and Zinc White. ACKNOWLEDGMENT This study has been partially supported by the agreements IAPH & UPO, UPO&ENEA and the Projects of Junta de Andalucia RIVUPH (HUM-6775) and Ministerio de Economía y Competitividad Project ART-RISK.

Resume : Recent advances in nanotechnology are enabling the development of new treatments focused on our cultural heritage, based on nanoscale properties of different materials. In this sense, silver nanoparticles (AgNPs) are remarkable owing to their biocide properties [1]. Stone monuments, which are subject to bio-deterioration, may be treated with these AgNPs tailored for use as biocide products with minimal visual impact and controlled permeability. We have developed different silver and titanium dioxide nanocomposites to be used as biocides on calcarenite stones from Utrera’s quarry (Seville, Spain), which is one of the main limestones employed in the Town Hall of Seville (XV-XIX Century). Two different syntheses of AgNPs have been employed, using sodium borohydride or sodium citrate as reducing agents. The nanocomposites obtained using sodium citrate have shown higher colloidal stability and reduced hydrodynamic diameter (as assessed by DLS and UV-Vis spectrophotometry studies) as well as better biocide effect. Optimum application conditions were established to maximize applicable concentrations to the stone material, while maintaining chromatic alterations due to the silver colloid below a given threshold. Ag/TiO2 nanocomposites are promising for application on calcarenites, though AgNP concentrations over 0.66 mg/ml are not suitable for cultural heritage applications, due to both the color changes and the blocking of the stone pores. [1] A.P.Zaderenko,C.Caro,M.J.Sayagués,J.L.Royo Sánchez-Palencia,R.Polvillo, Nanoestructuras biocidas, Patente P201330444, 2013. ACKNOWLEDGMENT This study has been partially supported by the Projects: Junta Andalucia RIVUPH (HUM-6775), Ministerio Economía y Competitividad Project ART-RISK, Junta Andalucía (P10-FQM-6615 and PAIDI FQM-319), Fondo Europeo de Desarrollo Regional (FEDER-Unión Europea) and Ministerio Economía y Competitividad (CTQ2013-48396-P).

Resume : Corals, pearls and shells are materials often used for artworks and are by themselves objects exposedin museum collections.The knowledge of the nature of the pigments in biogenic carbonates is of primary importance for a better conservation and for authentication purposes but the characterization of these precious objects requires non-invasive/non-destructive analyses. Raman microscopy is a powerful technique to identify both the inorganic phases (calcite, aragonite or vaterite) and to define the nature of the organic pigments in corals, shells and pearls, especially when Raman resonance conditions are attained. Mixtures of methylated (carotenoids) or non-methylated polyenes with different UV-VIS absorption spectra and chain lengths are responsible for the colors and their variations in mineralized organisms. Here we report on Raman measurements at 632.8 nm and at 473.1 nm (resonance) in calcitic and/or aragonitic samples from private collections or museums: freshwater and saltwater pearls, marine and terrestrial shells, Mediterranean and Asian corals including fakes and endangered species.Natural species show Raman frequencies typical of polyenic methylated or unmethylated chains. The nature of the pigment and the structure of the carbonate skeleton allow discriminating between natural speciesand to recognize artificial or artificially coloured material.

Resume : Various environmental pollutants in both gaseous and liquid phases can be decomposed into harmless species bysimple and efficient way by photocatalysis processes.Titanium dioxide is the most widely studied photocatalytic material and the photoactive titaniananoparticles, obtained by sol-gel process,may give promising self-cleaning coatings for building materials under UV irradiation. Absorption of visible light may be achieved by doping the nanocrystallinetitania. Here wereport on a test of N-doped TiO2nanoparticles by sol-gel, dispersed in an aqueous medium,for travertine limestone coating. X-ray diffraction, UV-VIS, Raman and X-ray photoelectron spectroscopies were used to characterize TiO2powders. According to the UNI-Normal protocols, water absorption by capillarity, surface wettability and colorimetric parameters were measured to assess the compatibility of the coatings. The activity of N-doped TiO2 sols and TiO2 coatingswas evaluated by the photocatalytic oxidation of methyl orange (MeO), Rhodamine B (RhB) and methylene blue (MB) under solar lamp irradiation. The synthesized titania is mainly nanocrystallineanatase,6-10 nm sized,with a small amount of brookite. Different N-doping procedures have significant effects on the chemical binding within the doped titanium dioxide particles. Doping by ammonia leads to Ti-N chemical interaction whereas the introduction of nitrogen by urea gives no clear evidence of the formation of Ti-N bonding. A fast photocatalytic discoloration of the organic dyes was measured for TiO2 sols and coatings on travertine. The TiO2-based treatment does not introduce colorimetric changes compared to the untreated limestone and does not alter the properties of the stone. Support from MAECI (project “NANO4HER, Nanotechnology at the service of cultural heritage preservation”, Italy-Israel Scientific and Technological Cooperation) is gratefully acknowledged.