Papers by Valeria Di Tullio
Applied Physics A, 2016
The use of nanotechnology in conservation is a relatively new concept. Usually, classical cleanup... more The use of nanotechnology in conservation is a relatively new concept. Usually, classical cleanup methods take into account the use of other chemicals: On the one hand they help the environment destroying pollutants, but on the other hand they often become new pollutants. Among the new oxidation methods called advanced oxidation processes, heterogeneous photocatalysis has appeared an emerging technology with several economic and environmental advantages. A new sol-gel method of synthesis of TiO 2 anatase is reported in this work using lithium and cobalt (II) salts. The activation energy of the doped photocatalyst was analyzed by solid-state UV-Vis spectrophotometer. The mobility of Li ions on TiO 2 NPs surface was studied by 7 Li MAS NMR spectroscopy. Use of doped nanotitania is suggested from authors for the removal of pollutants in confined areas containing goods that must be preserved from decomposition and aging phenomena.
Research for Development, 2014
XVII International Congress of Classical Archaeology, Rome; 09/2008
Magnetic Resonance in Chemistry, 2014
Consolidation and protection are among the most important treatments usually carried out in conse... more Consolidation and protection are among the most important treatments usually carried out in conservation of stone artifacts and monuments. In this paper, portable unilateral NMR and conventional techniques were used for investigating new multifunctional treatments based on tetraethoxysilane, silica, and polytetrafluoroethylene nanoparticles. The study was carried out on a very complex and heterogeneous porous stone such as tuff. NMR study allowed to obtain detailed information on the penetration depth of treatments, the hydrophobic effect, and changes in the open porosity caused by treatments. Physical and chemical inhomogeneities between the impregnated layers of tuff and the layers underneath were also detected. The average pores radius and pores interconnection obtained from NMR diffusion measurements were used for the first time to compare effects of different consolidating and/or protective treatments on stone. Because unilateral NMR technique is neither destructive nor invasive, investigation of treatments can be also carried out and optimized directly on buildings and monuments of interest for Cultural Heritage.
Surface Engineering, 2013
ABSTRACT The present work was aimed at characterising the materials and assessing the state of co... more ABSTRACT The present work was aimed at characterising the materials and assessing the state of conservation of the ‘Adorazione dei Magi’, a wooden panel painted by Bartolo di Fredi in the second half of fourteenth century. To this goal, innovative non-destructive investigation techniques such as portable Raman spectroscopy, visible reflectance spectroscopy and unilateral nuclear magnetic resonance, were used in situ in order to achieve surface and bulk compositional data. The former allowed the identification of the artist’s palette including cinnabar, red ochre, minium, carbon black, lead white, ultramarine blue, malachite and phthalocyanine green, while the latter provided information on the stratigraphic structure and state of conservation of the wooden panel.
Sensors, 2014
In recent years nuclear magnetic resonance (NMR) sensors have been increasingly applied to invest... more In recent years nuclear magnetic resonance (NMR) sensors have been increasingly applied to investigate, characterize and monitor objects of cultural heritage interest. NMR is not confined to a few specific applications, but rather its use can be successfully extended to a wide number of different cultural heritage issues. A breakthrough has surely been the recent development of portable NMR sensors which can be applied in situ for non-destructive and non-invasive investigations. In this paper three studies illustrating the potential of NMR sensors in this field of research are reported.
Near Surface Geophysics, 2013
Several factors affect antenna-soil coupling in a Ground Penetrating Radar (GPR) survey, like sur... more Several factors affect antenna-soil coupling in a Ground Penetrating Radar (GPR) survey, like surface roughness, lithology, lateral heterogeneities, vegetation, antenna height from the surface and water content. Among them, lithology and water content have a direct effect on the bulk electromagnetic properties of the material under investigation. It has been recently pointed out that the wavelet of the early-time portion of a radar signal is correlated to the shallow subsurface dielectric properties of a material. This result indicates that some information on such properties can be directly extracted from the analysis of GPR early-time traces. In the present paper, we use the early-time GPR signal, in terms of average envelope amplitude computed on the first half-cycle, to map the near-surface (few centimetres) lateral distribution of dielectric parameters, induced by changing the shallow water content on a concrete slab. This controlled experiment was specifically designed to study the effect of water content variations on antenna-material coupling, minimizing the influence of both surface roughness and heterogeneity. The quantitative control of the water in the shallow portion of the slab is performed by using a portable unilateral Nuclear Magnetic Resonance (NMR) sensor, which is able to determine the water content in the material on the basis of the measured proton density. The results show a matching pattern of the physical parameters measured with the two different techniques and a very high degree of linear correlation (r = 0.97) between the radar early-time signal average amplitude and the intensity of the NMR signal, which is proportional to the proton density, i.e., to the water content. This experiment suggests that the early-time approach could be used as a fast and high-spatial resolution tool for qualitatively mapping water content lateral variations in a porous material at shallow depth, using a ground-coupled single-offset antenna configuration and that a quantitative evaluation of the moisture content would require a calibration procedure. In a survey design several factors should be taken into consideration, like the investigation depth, the spatial resolution, the characteristics of the medium (e.g., granular or solid), the physical properties of the material, the site conditions and the reliability of the retrieved physical parameter in terms of water content estimator. If the required investigation depth is limited to a few metres, GPR represents one of the best options in terms of spatial resolution, fast acquisition time, extension of the investigated area and repeatability of the measurements (Annan 2004; Jol 2009; Barone et al. 2010). Such a technique is based on radio waves propagating through the medium and the water content value can be indirectly retrieved from the measurement of a signal velocity. In particular, several radar methodologies like the
Applied Physics A, 2013
ABSTRACT Nuclear Magnetic Resonance (NMR) methodologies were applied to characterize the constitu... more ABSTRACT Nuclear Magnetic Resonance (NMR) methodologies were applied to characterize the constitutive materials and the state of degradation of a contemporary painting. The investigation was mandatory to plan a suitable restoration. Noninvasive, portable NMR allowed the detection of degraded regions of the painting based on the measurement of longitudinal relaxation time. A few samples were investigated by high resolution solid state NMR and NMR in solution, which allowed us to identify the polyurethane constituting the artefact, to investigate the microstructure in detail, and to assess that the degradation process mostly affected the ethylene units used to cap the polypropylene oxide polymeric chain. As a matter of fact, a shortening of longitudinal relaxation time was accompanied by a degradation of ethylene units. The degradation of the inorganic loading was investigated by 27Al MAS, which evidenced the absence of penta-coordinated aluminum in degraded samples.
International Journal of Spectroscopy, 2012
Portable unilateral NMR was used to quantitatively map in a fully noninvasive way the moisture di... more Portable unilateral NMR was used to quantitatively map in a fully noninvasive way the moisture distribution in an ancient deteriorated wall painting before and after an intervention to reduce the capillary raise of water through the wall. Maps obtained at a depth of 0.5 cm clearly showed the path of the capillary raise and indicated that, after the intervention, the moisture level was reduced. Maps obtained by measuring the first layers of the wall painting were affected by the critical environmental conditions of the second hypogeous level of St. Clement Basilica, Rome, and by the presence of salts efflorescence and encrustations on the surface of the wall painting. The morphology and the elemental composition of salts investigated by SEM-EDS indicated that efflorescences and encrustations were mostly constituted of gypsum and calcite. The presence of these salts is explained with the presence of high concentration of carbon dioxide and sulphur-rich particles due to pollution which...
Reference Module in Chemistry, Molecular Sciences and Chemical Engineering, 2022
Microporous and Mesoporous Materials, 2017
Article Istory Xxxxxxxx Highly performing cleaning systems based on hydrogels for buildings and a... more Article Istory Xxxxxxxx Highly performing cleaning systems based on hydrogels for buildings and artefacts were studied by unilateral NMR. Specifically, the release and diffusion of water from gellan gum formulations at the gel stone interface were investigated. The study was carried out by applying gel formulations to stone specimens with different porosimetric properties, namely Yellow Tuff of Via Tiberina and Lecce stone. NMR measurements and a suitable processing of data allowed the obtainment of the total open porosity, the average pore size, and the tortuosity of the stones. Properly calibrated 1 H NMR depth profiles with micrometric resolution were used to evaluate the effective volume of absorbed water, the distribution of water in porous stone specimens, and the degree of saturation. The deformation coefficient of the gel after water release was also determined. The obtained results indicated that the performance of the gel depends not only on its physical-chemical properties but also on the porosimetric properties of the stone to which the gel is applied. Therefore, the knowledge of the porosimetric properties of the material is important for selecting a suitable and highly performing gel cleaning system.
Microchemical Journal, 2016
The effectiveness and the mechanism of copper stain removal from stones by agar gels was systemat... more The effectiveness and the mechanism of copper stain removal from stones by agar gels was systematically studied using marble laboratory specimens, stained and cleaned in well-controlled and reproducible conditions. The same cleaning procedure was also applied on the marble base of Napoleon's statue by A. Canova. The water release from agar gels to stones was investigated by capillarity absorption and unilateral Nuclear Magnetic Resonance. The cleaning by different agar gel formulations (pure and added with chemicals) was studied both on the stone substrate (optical microscopy and colour measurements) and in the gels (inductively coupled plasma-atomic emission spectrometry, electron paramagnetic resonance spectroscopy). Among the considered cleaning systems, the most effective ones for copper removal were agar gels 3% containing additives, with no significant difference among the used additives. However, agar gels with additives host copper in different ways: in gels added with ethylenediamine tetraacetic acid (EDTA), all copper centers are coordinated, while copper centers are also dispersed in water within gels added with ammonium citrate tribasic (TAC). The stain cleaning process of stones probably starts with the diffusion of water at the gel-stone interface, but it finds the driving force in the copper coordination.
Microchemical Journal, 2016
Abstract In this study a multi-analytical approach was used to characterize ancient and modern co... more Abstract In this study a multi-analytical approach was used to characterize ancient and modern constitutive materials and the stratigraphy of a Sienese wooden painting consisting of four cusps belonging to a lost Polyptych, by Andrea di Bartolo dated back to the late 14th century, repainted in the 16th century and partially restored and cleaned in the 20th century. In order to distinguish the original layers from the other ones, a comparison with the painting Adorazione dei Magi by Bartolo di Fredi (Andrea's father) dated to the 14th century, was performed. The painting Adorazione dei Magi was found to be in a very good state of conservation and provided a model of the artistic technique used in Sienese painting in the 14th century. In situ measurements by portable NMR were performed to investigate the stratigraphy of the paintings in a non-destructive and non-invasive way. By means of this technique, information about all layers constituting the paintings were obtained and used to plan the successive micro-sampling. High resolution NMR spectroscopy was applied on a few samples to characterize binders and organic substances. Specifically, solid state 13C and 31P CPMAS NMR spectroscopy and 1H NMR spectroscopy in solution were applied to characterize original and non-original materials. Other techniques such as ToF-SIMS, HPLC, IR and Raman spectroscopy were also applied.
ABSTRACT Water repellent treatment is one of the most important interventions usually carried out... more ABSTRACT Water repellent treatment is one of the most important interventions usually carried out in the conservation of stone materials. It is essential to choose a suitable product and then to ascertain its effect on a medium and long term basis. Obviously only after experimentation, first in laboratory and after in situ, the behavior of the treatment can be determined. Recently the CEN TC 346 has been trying to establish a common methodology to test in laboratory water repellent products applied to porous inorganic materials. The methodology and time of application can strongly influence the depth of penetration of a treatment into a porous structure. In this paper, a preliminary review by analyzing and highlighting some crucial elements in the study of water repellent treatment in stone specimens has been carried out.. Besides, a comparison has been made between the results of our recent studies of water repellent treatment on a sandstone and a biocalcarenite with the aim of showing the close correlation between the time of application of the product and its penetration depth on stone evaluated by Unilateral NMR depth profile and capillarity absorption.
Magnetic Resonance in Chemistry
Heavy metal carboxylate or soap formation is a widespread deterioration problem affecting oil pai... more Heavy metal carboxylate or soap formation is a widespread deterioration problem affecting oil paintings and other works of art bearing oil-based media. Lead soaps are prevalent in traditional oil paintings because lead white was the white pigment most frequently chosen by old masters for the paints, and in some cases for the ground preparations, until the development of other white pigments from approximately the middle of the 18th century on, and due to the wide use of lead-tin yellow. In the latter part of the 19th century, lead white began to be replaced by zinc white. The factors that influence soap formation have been the focus of intense study starting in the late 1990s. Since 2014, NMR studies have contributed a unique perspective on the issue by providing chemical, structural, and dynamic information about the species involved in the process, as well as the effects of environmental conditions such as relative humidity and temperature on the kinetics of the reaction(s). In this review, we explore recent insights into soap formation gained through solid-state NMR and single-sided NMR techniques.
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Papers by Valeria Di Tullio
La pubblicazione riporta una delle tesi di laurea vincitrici del Premio Giovanni Urbani-Menmosyne.