Monica Favaro

ABSTRACT Dense, crack-free thin films (<5 mm) of the nanostructured scandia-zirconia system (Sc 2 O 3 :ZrO 2) stabilized in the cubic-fluorite phase (c-ZrO 2) are deposited through conventional low-pressure metal-organic(LP-MO) CVD by using b-diketonate metal complexes as precursors [(Zr(tmhd) 4 and Sc(tmhd) 3 , with –tmhd ¼ 2,2,6,6-tetramethyl-3,5-heptanedionate]. The compositional (energy dispersive X-ray spectroscopy – EDX), structural (X-ray diffraction – XRD) and morphological (field emission gun– environmental scanning electron microscopy – FEG-ESEM) analyses, confirmed the growth of dense partially and fully stabilized ZrO 2 , a suitable electrolyte for solid oxide fuel cells (SOFC). Results of impedance spectroscopy, which investigates the electrical conductivity of coating, deposited as thin as possible to guarantee the uniform covering of a porous substrate, are reported. Results of thin films of yttria-zirconia system (Y 2 O 3 :ZrO 2), deposited with the same method, are also reported for comparison.

Nowadays, the goal in oncological diagnostics is to tackle the growth and the spread of cancer by developing new cost-effective screening techniques for early diagnosis, in order to both improve the survival rate of patients and reduce costs related to the various prevention programmes. In an interdisciplinary context it has been designed a new method to early detect tumor biomarkers present either in blood or in urine based on the use of lanthanide (Ln) complexes. By exploiting a time-resolved technique we aim at achieving a detection limit lower than 1 U/mL and/or obtaining a faster, easier and less expensive sensing method alternative to the widely employed ELISA (enzyme linked immunosorbent assay). In fact, lanthanides offer several advantages compared to the common organic labels. The luminescence lifetime of the specific signal is several orders of magnitude longer than the non-specific background, thus enabling the label to be measured without background interference (time resolution). The large Stokes’ shift and the narrow emission peak contribute toward increasing the signal-to-noise ratio. We worked following two routes. In the first one, called CHIA (Chemiluminescence ImmunoAssay), we designed to develop a novel type of biosensors based on changes of luminescence intensity or wavelength of lanthanide complexes. We decided to investigate tryptophan (Trp) residues as possible donors in energy transfers and serine residues as possible bioconjugation sites of lanthanide complexes to the monoclonal antibodies. According to the Dexter’s mechanism, a LRET from Trp to the metal ion could occur. Since the Trp-Ln distance is a relevant factor in determining the RET effectiveness, we pointed out our attention to a specific type of antibody, as an example. We chose colo-rectal cancer as it is a quite common tumor. After having looked for the exact sequence of CA19-9 mAb and the structure of similar Fab with an high sequence homology, a study at a biochemical level of the antibody structure and the involved distances revealed the presence of many couples Trp-Ser spaced less than 10 A. This encouraged the subsequent digestion trials of a cheap test antibody by using ficin protease yielding F(ab’)2 fragments, characterized and purified by means of SDS-PAGE and SEC. In the second approach, called LIA (Luminescence ImmunoAssay), six lanthanide complexes have been synthesised and widely characterized by using two different type of ligands: two dithiocarbamato and four coumarin-3-carboxylic acid (HCCA) derivatives. We studied luminescence emission for all complexes in acetonitrile, water and dimethyl sulfoxide.

This paper presents the study of calcium alkoxides from their synthesis to the final application as CaCO3 precursors for calcareous materials consolidation. These innovative nano-structured molecules have been specifically designed to reach the requirements of compatibility and effectiveness when consolidating cultural heritage carbonaceous substrates such as marble and wall paintings. The first step was the selection of solvents used to solubilize the alkoxide. Then we selected two types of substrates in order to test its performances: samples of weathered Carrara marble (5x5x1 cm) and wall paintings specimens of frescoes and a secco techniques of green earth, yellow ochre, azurite, lead-tin yellow and cinnabar-white lead mix. Variations of ultrasonic velocity, observations of the coatings by FEG-ESEM and spectrophotocolorimetric measurements were done to evaluate the consolidation effects of the alkoxides and the absence of side-effects such as whitening. The calcium triethylen gl...

Two new minerals – manganoblödite (IMA2012–029), ideally Na2Mn(SO4)2·4H2O, and cobaltoblödite (IMA2012–059), ideally Na2Co(SO4)2·4H2O, the Mn-dominant and Co-dominant analogues of blödite, respectively, were found at the Blue Lizard mine, San Juan County, Utah, USA. They are closely associated with blödite (Mn-Co-Ni-bearing), chalcanthite, gypsum, sideronatrite, johannite, quartz and feldspar. Both new minerals occur as aggregates of anhedral grains up to 60 μm (manganoblödite) and 200 μm (cobaltoblödite) forming thin crusts covering areas up to 2 × 2 cm on the surface of other sulfates. Both new species often occur as intimate intergrowths with each other and also with Mn-Co-Ni-bearing blödite. Manganoblödite and cobaltoblödite are transparent, colourless in single grains and reddish-pink in aggregates and crusts, with a white streak and vitreous lustre. Their Mohs' hardness is ∼2½. They are brittle, have uneven fracture and no obvious parting or cleavage. The measured and calc...

Opperulaktebehandelingen zoals steenverstevigen, hydrofoberen en antigraffiti bestaan al meer dan 100 jaar. Op het gebied van steenverstevigers wordt gebruik gemaakt van een reeks verschillende chemische producten, waarvan kiezelzure esters (ethylsilicaten zoals TEOS) thans de meest gangbare zijn (Nijland et al. 2009). Ze kennen echter hun beperkingen: Er ontstaan van krimpscheuren tijdens het drogingsproces en ze hebben een geringe affiniteit met kalksteen en kalkbebonden materialen. Het nieuwe kiezelige bindmiddel dat door de steenversteviger gevormd wordt, hecht veel minder goed aan een kalkgebonden ondergrond dan aan een chemisch vergelijkbare kiezelige ondergrond. Om deze problemen op te lossen, zijn de afgelopen jaren verschillende mogelijkheden onderzocht: Het toevoegen van een opperulaKe-actieve stof of silicadeeltjes van nanogrootte om de krimp tegen te gaan, danwel het modificeren van de kiezelzure ester of het toepassen van een voorbehandeling om de hechting op carbonaat ...

L'entree monumentale du Palais des Doges de Venise, connue sous le nom de Porta della Carta et universellement reconnue comme, un chef-d'œuvre de l'art gothique, a ete restauree entre 1976 et 1979. L'etat de conservation actuel des sculptures gothiques en marbre qui decorent l'arc, representant les quatre Vertus (la Temperance, la Prudence, la Charite, et le Courage), a recemment ete evalue. Cette evaluation s'est faite par le biais d'une etude chimique minutieuse de la surface et de l'examen des sculptures a l'aide d'ultrasons. Les buts de cette etude etaient d'evaluer le degre et le type de deterioration dont souffrent ces oeuvres, ainsi que l'efficacite des consolidants et hydrofuges appliques lors de la precedente restauration et leurs eventuelles alterations, et finalement d'etablir des options possibles pour une future strategie de conservation. Les echantillons de surface preleves sur chacune des quatre Vertus ont ete analys...

Since ancient times, several products have been used to prevent the deterioration of building surfaces due to the adverse environmental factors in Venice. Natural products, mainly oxalate bearing solutions, waxes and other mixtures of vegetal and animal derivatives, were primarily used in the past to strengthen the stone surface and to prevent the effect of marine aerosols. In XIX century new products were introduced in the field thanks to the strong improvement of chemistry, which brought to several recipes for stone treatment. Most employed in Venice at that time were the silicate and fluosilicate treatments according to the Fuchs (1818), Kulmann (1854), Ransome (185660) and Kessler (1883) patents. Notwithstanding the innovations, the use of natural products was not abandoned until the middle of XX century, when polymers were introduced in the market and suddenly took the place of most traditional products, also in the occasion of the deleterious flood in 1966, that made clear the...

The use of plasma in the fi eld of cultural heritage has been fi rstly applied for the con- servation of archaeological iron artefacts and silver objects, for disinfection and consolidation of paper and more recently for conservation of polymers in modern art and cleaning of architectural surfaces. Notwithstanding these fi rst applications, the plasma

The impact of climate change on built heritage and the development of new preventive conservation methods are nowadays topics seen as priorities by the scientifi c community involved in cultural heritage preservation. However, damage processes due to the environment-materials interaction are irreversible and often inevitable for outdoor built heritage. Research has therefore recently been focusing on the development of new materials specifi cally geared towards conservation use, such as consolidating and protective treatments, which meet the criteria of compatibility and durability. The ongoing European Project NANOMATCH has as one of the main objectives the development of an innovative nanostructured material for the consolidation of carbonate stones. An alkaline earth alkoxide as precursor of calcium carbonate has been synthesized to overcome the limits that traditional consolidating agents exhibit. As part of the research work, fi eld exposure tests are planned for the evaluation...

Conservation of historical stone and stone-like surfaces of built heritage has usually been performed with organic materials, such as polymers either for consolidation of decayed and fragile surfaces or to reassembling detached fragments by gluing. Moreover modern materials and devices have been used to strengthen those substrates in order to enhance even their mechanical properties. During time, the low compatibility of some of those repairing products with original artifacts turned out on a further degradation that needed to be addressed with time-consuming and expensive retreatments or structural retrofi t. Taking into account the issues of compatibility and durability for a sustainable conservation of historical stone and stone-like surfaces, geopolimeric materials are under investigation in our laboratories to fulfi ll those requirements. During the past decades, geopolymer composites “alkali activated” geopolymers were deeply investigated as non-cement binding materials for di...

The study presents a preliminary assessment of Fibre Reinforced Geopolymer (FRGP) as strengthening material for masonry buildings. FRGPs were made with three different geopolymeric matrices and four different reinforcements: two Basalt nets and two Ultra High Strength Steel fabrics. Innovative strengthening materials should take into account fundamental restoration criteria. Geopolymeric matrices have the potential to comply with those requirements thanks to their tailored chemical and mechanical characteristics, while also providing heat-resistant performances better than organic polymeric matrices. The applicability of geopolymers as a matrix for composite materials aimed at structural strengthening of brick masonry was investigated with an interdisciplinary approach. Compression, splitting and pull-off tests were performed to check the main mechanical characteristic and adhesion to two clay brick substrates of the matrices and composites (Figure 1a,b). Microscopy and SEM-EDS analyses were performed to check the compatibility of geopolymers with both fibres and clay brick substrates. The experimental tests and the main results for selecting effective FRGPs are presented.

Abstract In the field of cultural heritage conservation, wall paintings treatment is a particularly complex issue, which requires a suitable choice of materials. In this paper, two innovative calcium alkoxides, calcium tetrahydrofurfuryl oxide [Ca(OTHF) 2 ] and calcium ethoxide [Ca(OEt) 2 ], are proposed as new products for the consolidation of wall paintings. They were developed during the NANOMATCH European project and their efficacy, compatibility with the substrate and durability were evaluated in comparison with commercial products on both model and real samples. Model samples were exposed in four different sites around Europe to investigate the treatments’ behaviour under different climatic conditions. The main research results are reported here: alkoxides showed to be a good option for wall paintings’ consolidation especially in presence of certain binders and pigments. Finally, an impact testing device was used for the first time for the evaluation of the consolidants’ efficacy and thus proposed as a reliable methodology for their performance assessment.

Metal alkoxides are metal-organic compounds characterized by the presence of MOC bonds (M = metal). Their chemistry seems to be, in principle, relatively simple but the number of possible reactant species arising as a consequence of their behavior is very remarkable. The physico-chemical properties of metal alkoxides are determined by many different parameters, the most important ones being the electronegativity of the metal, the ramification of the ligand, and the acidity of the corresponding alcohol. Their reactivity makes them suitable and versatile candidates for many applications, including homogeneous catalysis, synthesis of new ceramic materials through the sol-gel process and, recently, also for Cultural Heritage. Metal alkoxides are characterized by a strong tendency to give clusters and/or oligomers through oxo-bridges. Mass spectrometry has been successfully employed for the characterization of metal alkoxides in the gas-phase. Electron ionization (EI) allowed the assessment of the molecular weight and of the most relevant decomposition pathways giving information on the relative bond strength of differently substituted molecules. On the other hand, information on the reactivity in solution of these molecules have been obtained by electrospray ionization (ESI)-matrix assisted laser desorption ionization (MALDI) experiments performed on their reaction products. These data were relevant to investigate the sol-gel process. In this review, these aspects are described and the results obtained are critically evaluated. © 2016 Wiley Periodicals, Inc. Mass Spec Rev.

In order to explain why different forms of decay are present on a building facade some samples were taken from different areas of many monuments. Macroscopic observations of the forms of decay were correlated with quantitative analytical data in order to build up a simple model which was able to explain in a general way the decay phenomena. This simplified model was tested on several Venetian monuments and the features visible on stone surfaces correspond to different degree of deterioration. The quantitative analytical data were associated with the different forms of decay, which were defined as white washing, dirt accumulation and dirt washing. The results obtained showed that the features visible on stone surfaces corresponded to different degree of deterioration and the sulphate formation is greatest in the black dendrite-shaped crusts which are generally formed at the interface between the white washing areas and the sheltered ones, which were defined as dirt washing area.

Innovative technologies are increasingly being applied in the cultural heritage domain, leading to specific requirements in the effectiveness and harmonization of instrumental methods. Funded on metrological basis, the assessment of the reliability of diagnostic tools includes the comparison between different methods revealing the same quantity or kind of degradation. The investigation deals with an integrated approach to detect the conservation state of frescoes. A comparison of two diagnostic methods, identifying detachments in mural paintings, was carried out in the upper hall of the Oratorio of San Rocco in Padua, a restoration yard become a scene of a participated experimentation. The activity was coordinated between two working units and the restorers for assessing the range of validity of both methods, their strengths and limits, their ability to turn the outcomes into a meaningful indication for the restorers. The frescoes were analyzed through the Acoustic Energy Absorption...

ABSTRACT High surface-to-volume ratio Co3O4/TiO2 heterojunctions were fabricated by combining different methods. Atomic layer deposition (ALD) and a photochemical method were used to coat polystyrene (PS) 3D-Direct Opal (3D-DO) structures on conductive ITO substrates. Firstly, 3D-DO of PS were crystallized on ITO substrates to form the high surface-to-volume ratio template via a self-assembly method. A low-temperature ALD TiO2 film was infiltrated onto the PS opal structure. Then, the PS template was removed by a thermal treatment in air at 450 °C for 5 h. Hollow anatase phase nanospheres were obtained, crystallized in a face centered cubic (FCC) lattice with the (111) plane oriented parallel to the substrate surface. Finally, the hollow TiO2 nanospheres were coated with Co3O4 via a photochemical method. This ordered 3D nanostructure with designed morphology may find applications as surface-enhanced materials for photovoltaic devices.TiO2 hollow nanospheres obtained via low-pressure ALD (a) and Co3O4/TiO2 heterostructure (scanned region: 1.5 μm) (b).