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Abstract The treatment of stone surfaces for their protection from ageing caused by natural and anthropogenic effects is an open issue in materials development for Cultural Heritage. We thought interesting to verify the suitability of a modified cellulose biofilm filled with halloysite nanotubes as wax compatibilizers to design a protecting layer. A hydraulic mortar was selected as a stone prototype. To improve the physico-chemical properties of the covering layer, wax microparticles have been incorporated to control transport, consolidation and wettability features. In particular, different application protocols have been studied, namely brushing and spraying, to assess whether the proposed procedures can be scaled up. Colorimetric analysis has been carried out to evidence the applicability in terms of color alteration after the treatment. Water adhesion was investigated by measuring the contact angle values as a function of time to obtain information on spreading and adsorption phenomena. These physico-chemical properties have been correlated to the microstructure evidenced by both electron and optical microscopies. Graphic abstract

Superhydrophobic coatings were fabricated through a one-step electrochemical process onto the surface of 316L stainless steel samples. The presence of hierarchical structures at micro/nanoscale and manganese stearate into the coatings gave superhydrophobicity to the coating, with contact angle of ~160°, and self-cleaning ability. Corrosion resistance of 316L samples was also assessed also after the electrodeposition process through Electrochemical Impedance Spectra recorded in an aqueous solution mimicking seawater condition.

In this work, a lignocellulosic flour was achieved by grinding the cladodes of Opuntia Ficus Indica and then added to a poly-lactic acid (PLA) in order to prepare biocomposites by melt processing. The influence of filler content and size on the morphological, rheological, and mechanical properties of the green composites was assessed. Moreover, solvent-aided filler extraction enabled to evaluate the homogeneity of filler dispersion, as well as the effect of processing on the geometrical features of the fillers. The experimental data obtained by tensile tests proved to be remarkably higher than those predicted by Halpin–Tsai model, presumably due to the capability of the polymer to enter the empty channels of the fillers, thus dramatically increasing the interphasic region.

Cu2O/ZnO:Al (AZO) and Cu2O/ZnO/AZO heterojunctions have been deposited on glass substrates by a unique three-step pulsed laser deposition process. The structural, optical, and electrical properties of the oxide films were investigated before their implementation in the final device. X-ray diffraction analysis indicated that the materials were highly crystallized along the c-axis. All films were highly transparent in the visible region with enhanced electrical properties. Atomic force and scanning electron microscopies showed that the insertion of a ZnO layer between the Cu2O and AZO films in the heterojunction enhanced the average grain size and surface roughness. The heterojunctions exhibited remarkable diode behavior and good rectifying character with low leakage current under reverse bias. The presence of the ZnO interlayer film significantly reduced the parasitic and leakage currents across the barrier, improved the quality of the heterostructure, made the energy band between AZO and Cu2O layers smoother, and eliminated the possibility of interface recombination, leading to much longer electron lifetime.

This paper presents the results of an experimental study that had the goal of understanding the effects of treatment with polyethylene glycol (PEG)/nanolime mixtures on collapsible soil behaviour. In a previous study, the use of pure PEG offered a good improvement in the stability of collapsible soil, but the stabilisation effect only lasted for a limited time. To investigate the stabilisation potential of PEG/nanolime systems for collapsible sand, different mixtures were prepared at increasing nanolime weight ratios. The suitability of the stabilised soil was examined on the basis of collapsibility, oedometer, shear, and water vapour permeability tests, and through optical microscopy and scanning electron microscopy observations. The stabilisation effects were analysed by comparing the mechanical behaviour of the sand before and after each treatment. The results showed that even though using various mixtures had different effects on the behaviour of collapsible soils, the treatment produced a significant change in the geotechnical behaviours of the sand in relation to the collapse potential, permeability, compressibility, and shear strength.

This paper aims to propose and characterize a sustainable hydraulic mortar entirely obtained by the reuse of waste materials, with marble slurry coming from quarries in the north-western Sicily and glass powder coming from a waste collection plant in Marsala (Province of Trapani). The first was used as raw material to produce the mortar binder by a kilning and slaking process, while the second was used as a pozzolanic additive. The chemical and morphological characterization of the marble slurry was done by XRD, FTIR, STA and SEM analyses. Glass powder was analyzed through particle size distribution measurements, XRD and standard pozzolanic tests. Hydraulic mortars constituted by slaked lime from kilned marble slurry and waste glass powder (LGS) were prepared beside commercial Natural Hydraulic Lime (NHL) based mortars (NGS) and air-hardening lime (LSS)-based mortars. Mechanical and absorption properties of the mortars were investigated as a function of the grain size of the glass powder by means of three-point bending and compressive strength tests, capillary uptake, helium pycnometry and simultaneous thermal analysis. The results demonstrated that the formulation LGS exhibits significantly improved mechanical and absorption properties compared to air-hardening mortars (LSS). It confirms the possibility of producing a more sustainable hydraulic mortar exclusively from waste materials for civil engineering.

The paper presents the results of a characterization of kinetic characteristics of pozzolanic reaction with the aim to investigate the time-dependent modification of clay properties as a consequence of mixing with lime. Results of chemical analyses are in agreement with the increase of mechanical properties and with the observed microstructure modifications up to one year of curing time. The rate of development of pozzolanic reactions seems to be almost constant while the time required for their completion is dependent on the lime content. Pozzolanic products are responsible for the time reduction of swelling strain upon saturation as well as for the increases of yielding stress, stiffness and hydraulic conductivity. However, the data analysis proves that a significant component of settlement measured during loading may be induced by the secondary compression process (creep). These results are significant for the prediction of the long-term behaviour of the stabilized soil.

Nowadays, there is a growing need to reduce the environmental impact generated by the use of inorganic materials for building applications. The aim of this work is to investigate the bio-lime based mortar flexural toughness improvement due to the addition of common reed fibers (Arundo donax L.) in order to evaluate their possible application as ductile eco-compatible prefabricated bricks or laying and joint mortars for masonry. Different sets of specimens were tested by varying the fiber weight content and the fiber length. Moreover, chemical treatments with Linseed Oil and Polyethylene glycol (PEG) were performed to improve the physical and mechanical properties of the fibers as well as the fiber/matrix interfacial adhesion. The Mechanical characterization of the neat and treated fibers was performed through Single Fiber Pull-out Test and Single Fiber Tensile Test. The quasi-static mechanical properties of the composites were evaluated through Three-Point Bending and Compressive tests. Finally, an analytical model proposed in the literature has been used to evaluate the parameters that influence the post-fracture behavior of the composites. Overall, the findings of this study are valuable to understand the flexural behavior of new eco-compatible natural fibers reinforced mortars for masonry application providing scientific evidence of the effectiveness of giant reed fibers in the manufacturing of green building materials, as bricks or laying mortars.

This study reports a new simple method to determine the crystallinity of anatase and rutile TiO2 photocatalysts. The crystallinity degree of various anatase and rutile samples was estimated by XRD analysis from the ratio among the full width at half maximum intensities of the main diffraction peaks of anatase or rutile and the (111) peak of CaF2 as internal standard. The photocatalytic activity of selected powders was tested employing the photodegradation of 4-nitrophenol in aqueous solution as probe reaction. The results showed that the photoactivity of the investigated samples increased with increasing crystallinity and crystallite size.

Al doped ZnO nanoparticles (labeled as x% A-ZnO, x = 0.0, 0.5, 1.0, and 1.5) were synthesized by a simple sol-gel method, characterized and tested as photocatalysts for the degradation of a model compound under UV-light irradiation. Diffuse reflectance spectroscopy (DRS) and photoelectrochemical analysis have been performed to evidence their optical and electronic behavior. The structural features of the powders were highlighted by means of specific surface area (SSA) analysis, X-ray diffraction (XRD), Fourier-transform infrared (FTIR) and Raman spectroscopy. Al doping results in enhanced photocatalytic activity of the modified powders with respect to pure ZnO. In particular, the highest activity was achieved with the 1.0% A-ZnO sample. The presence of Al did not significantly change neither the optical absorption nor the electronic structure of the powders. In fact, the observed blue shift of the band gap and cathodic shift of the quasi Fermi level of the modified powders occurred only at a virtually negligible extent. On the other hand, the structural analysis evidenced that the enhanced photocatalytic activity may be ascribed to the important surface defectivity induced mainly by substitution of Zn2+ by Al3+ ions and to the deriving higher hydrophilicity of the Al doped samples.

In this study the Madonna del Soccorsoo della Mazza wooden sculpture has been analysed by an interdisciplinary and integrated approach. The polychrome sculpture, dating back to the 18thcentury, comes from the church of the Madonna del Soccorso or della Mazza (1604) situated in Via Maqueda, in Palermo and it was placed on the main recess of the altar. All steps of the conservation project, from the preliminary study to the choice of materials and the restoration procedures have been accompanied and supported by diagnostic and scientific analysis. In order to evaluate the state of conservation of the sculpture and the technique employed to construct the support, computer tomography study was performed. Optical microscopy allowed to identify the wooden species and to verify the presence of microbial colonization or insect infestation. Scanning electron microscopy, combined with energy dispersive X-ray analysis (SEM/EDS), as well as XRF (X-ray fluorescence spectroscopy), were used to characterize paint stratigraphy and pigments. Sampling by sterile swabs and in vitro microbial culture has been performed to obtain the biological colonization.

The structural and photoelectrical properties of Al-doped ZnO (AZO)/SiC/p-Si and AZO/SiC/n-Si heterojunctions, fabricated at low temperature by pulsed laser deposition, were investigated by means of a number of techniques. Raman analysis indicates that SiC layers have the cubic 3C-SiC phase, whilst X-ray diffraction measurements show that AZO films exhibit a hexagonal wurtzite structure, highly textured along the c-axis, with average crystallites size of 35.1 nm and lattice parameter c of 0.518 nm. The homogeneous and dense surface morphology observed by scanning electron microscopy was confirmed by atomic force microscopy images. Moreover, UV–Vis-NIR spectra indicated a high transmittance of SiC films in the region 550–2500 nm, about 80% transmittance of AZO films in the 450–1000 nm region, and optical band gaps in good agreement with literature. These results prove that pulsed laser deposition is a low-cost technique suitable to grow SiC and AZO films with excellent material properties. The effect of the Si doping on the current transport mechanisms in the heterojunctions was investigated by current-voltage measurements under dark and white light illumination. Both heterojunctions exhibit a diode behaviour and relatively low leakage current, with a noticeable superiority for the AZO/SiC/n-Si device also under illumination, with an illumination/dark ratio of about 400. Our results indicate that the AZO/SiC/p-Si heterojunctions, with higher values of ideality factor, series resistance and lower rectifying ratio, have a complex current transport compared to the diodes grown on n-type Si. Additionally, capacitance-voltage measurements and Mott-Schottky plot allowed to determine a built-in potential of 0.51 V for the Al/AZO/SiC/p-Si/Al device.

Fibers are often used as reinforcement of brittle materials, like mortars, in order to modify their mechanical behavior; particularly the modification in post-cracking toughness, induced by low elasticity modulus fibers in the artificial stone material, is the main goal in natural fibers mortar manufacturing. In this work Arundo donax L. fibers are used to reinforce lime mortars according to the characteristics of this plant, very commonly available and with high mechanical properties, similar to bamboo, traditionally used in buildings in Spain. Influence of fibers’ length and weight ratio is studied. Particularly, three different fibers’ lengths, 4, 8 and 12 centimeters, and three weight ratio, 0.5, 1 and 2% are used. The experimental characterization focused on bending and compression tests on mortars’ samples as well as tensile and pull out tests on single fiber. Overall, according to experimental results, mechanical flexural properties of the mortar are significantly improved by the addition of natural fibers at different weight contents and lengths, optimal fibers’ weight ratio and length was individuated.

La Sala dei Venti è uno dei più suggestivi luoghi del Palazzo dei Normanni a Palermo, si tratta di una struttura sita all’interno della Gioaria, una torre medievale dell’originale nucleo arabo-normanno, antistante la Sala di Ruggero, coperta da un soffitto ligneo dipinto, risalente al XVIII secolo, al centro del quale campeggia una rosa dei Venti che dà il nome all’ambiente. Le porzioni superiori delle pareti e la copertura, soggette nel tempo a numerosi restauri e rifacimenti, presentano una ricca decorazione dipinta suddivisa in tre livelli: quello superiore costituito dal soffitto dipinto (parzialmente incamottato); quello intermedio costituito dai dipinti murali con decorazioni a finto marmo; il livello inferiore costituito da dipinti murali con decorazione a finto mosaico su fondo argentato-dorato. Sfortunatamente grandi estensioni delle superfici decorate versano in cattive condizioni di conservazione, principalmente a causa di pregresse infiltrazioni d’acqua dal tetto, che hanno generato importanti dilavamenti degli strati pittorici e di preparazione, distacchi e cadute, soprattutto sul soffitto dipinto e su due delle quattro pareti decorate a finto mosaico. Per salvaguardare questo patrimonio, l’Assemblea Regionale Siciliana (ARS) ha previsto un intervento di restauro, avendo efficacemente risolto il problema delle infiltrazioni con il rifacimento del sistema di copertura. Preliminarmente alla stesura del progetto di restauro, l’ARS ha avviato un sistematico studio diagnostico e conoscitivo dei materiali qui presentato. Sono state quindi eseguite indagini non invasive e non distruttive in situ e indagini micro-distruttive su campioni prelevati ad hoc volte a definire la composizione materiale e i fenomeni di degrado in atto, dovuti sia alle condizioni termoigrometriche non favorevoli, all’invecchiamento dei materiali e alle pregresse intese infiltrazioni delle acque piovane. L’osservazione preliminare e l’indagine termografica hanno confermato l’assenza in atto di infiltrazioni d’acqua, definitivamente risolte dalla nuova copertura, e di fenomeni di condensa sulle superfici dipinte, anche grazie alla presenza di griglie di aerazione su più livelli. Inoltre, l’incrocio dei dati termografici e quelli dei rilievi tramite pacometro ed endoscopio ha messo in evidenza la struttura del tetto e permesso di individuare i sistemi di connessione tra le tavole. Le indagini XRF, Raman e FT-IR hanno portato all’identificare dei materiali pittorici, originali e di restauro. Il riconoscimento dei pigmenti ha fornito un supporto per la datazione indiretta delle fasi originali e dei successivi interventi. Le ridipinture sono a base di una resina alchidica, identificata in GC-MS. Le stesure pittoriche originali del soffitto ligneo sono risultate essere a base di una tempera a uovo, applicata su uno strato di preparazione a gesso e colla animale; le dorature sono in foglia d’oro. Anche le specie lignee e le fibre tessili dell’incamottatura sono state identificate. Lo studio del livello intermedio a finto marmo ha evidenziato la presenza di decori geometrici in buono stato di conservazione occultati da fasce di carta con stesura grigio-bianca a base di bianco di titanio intervallate da cornici lignee a falso oro. Infine, per i dipinti murali del terzo livello, le indagini hanno evidenziato la presenza di una diversa stratigrafia ed in particolare di uno strato bituminoso presente al di sotto dello strato pittorico nelle porzioni più degradate. L’indagine di fluorescenza UV e FT-IR ha localizzato e identificato, su alcune superfici, la presenza diffusa di una resina chetonica di restauro in corrispondenza di una parete che mostrava un peculiare fenomeno di crettatura. Le indagini, che costituiscono ad oggi il primo studio scientifico sui materiali degli apparati decorativi della Sala dei Venti, hanno permesso di ricavare informazioni utili per la programmazione dell’intervento di restauro, ma anche per la ricostruzione degli interventi pregressi e delle fasi cronologiche di realizzazione dell’opera

During the last six years, at the University of Palermo, a group of academics has been involved in a project called “MENTORE” (“Modifying and ENhancing Teaching through peer Observation and Reflections with Experts”). The objectives of the project are: to help teachers improve their teaching, through the help of two mentors; to experiment new approaches in pilot courses to extend, if useful, to other ones; and to change the traditional model of academic teaching based on one single teacher with the class to go towards a model where there is a group of teachers working together in search of improvements. All the participants of the MENTORE project attend to lectures/workshops on teaching and learning and participate to meetings where they share experiences and ideas. In the program, each participant has two mentors that help him/her to improve the quality of his/her teaching. The two mentors are other academics that participate to the program. Indeed, each participant is both mentor and mentee during the same year. Mentors follow some of the lectures of the mentee, meet the students in the final part of the course in order to collect their opinion and, finally, meet the mentee in order to discuss the actions to carry out for improving the quality of his/her teaching. This chapter describes the aforementioned peer observation practice adopted at the University of Palermo and focuses on the role of mentors describing their activities during the peer observation process

La zincatura viene comunemente effettuata su acciaio al carbonio per impartigli una protezione attiva, ossia una protezione catodica per anodo sacrificale, oltre che una protezione fisica di tipo barriera. La zincatura potrebbe essere utilizzata anche per barre di armature nel calcestruzzo armato nei casi in cui strutture debbano essere fabbricate in ambienti particolarmente aggressivi, quali atmosfere marine e/o industriali, dove il composito calcestruzzo/metallo può subire carbonatazione e/o attacco da cloruri. Tuttavia, la zincatura ha un effetto collaterale, ossia diminuisce l’aderenza delle barre causando problemi alla struttura. Questa controindicazione ne ha limitato l’uso in questo ambito. Il processo che si vuole brevettare aumenta l’aderenza delle barre zincate senza compromettere la protezione catodica impartita da dallo zinco all’acciaio. È un processo electroless, che utilizza reagenti a basso costo e non tossici e che avviene a temperature di circa 70-80°C. Esistono due tipi di impianti che realizzano la zincatura su acciaio al carbonio: quelli che usano un bagno di zinco fuso (zincatura a caldo) e quelli che usano un processo elettrochimico (zincatura per elettrodeposizione). I layout degli impianti esaminati per entrambe le tecnologie integrerebbero facilmente le vasche necessarie per effettuare il trattamento oggetto di questo brevetto, considerando anche la possibilità di integrazione termica per mantenere la vasca alla temperatura a cui deve avvenire il processo. Le ricadute applicative dell’invenzione sarebbero estremamente interessanti in termini di durabilità di strutture in calcestruzzo armato che potrebbero così beneficiare di una più lunga vita utile di esercizio grazie alla protezione catodica attiva offerta dalla zincatura.

Nowadays sustainability is one of the main concept in building construction, both considering energy saving buildings and life cycle assessment of building materials. According to these considerations, in this work the use of recycled and waste materials to produce a binder and the use of a natural fiber as reinforcement are investigated to obtain a sustainable mortar. Particularly, lime is obtained by kilning waste marble slurry from marbles quarries in western Sicily; pozzolanic aggregate is obtained by grinding glass powder from urban waste collection; natural fibers come from a widespread grass: Ampelodesmos Mauritanicus also known as diss. Scanning electron microscopy and helium picnometry have been performed to characterize diss fibers. Samples with different fibers volume percentage have been prepared and subjected to three-point bending and compression tests, in order to verify the modification of resistance related to the presence of fibers; moreover, capillary uptake and thermal conductivity have been evaluated.The results show a great influence of fibers’ percentage on both mechanical and environmental properties of mortars, resulting in lowering of mechanical resistance and thermal conductivity.

The use of natural fibres in cement composites is an expanding research field as their use can improve the mechanical and thermal behavior of cement mortars and reduce their carbon footprint. In this paper two different wild grasses, i.e. Pennisetum Setaceum, also known as crimson fountaingrass, and Ampelodesmos Mauritanicus, also called diss, are used as source of natural fibres for cement mortars. The principal aim is to evaluate the possibility of using the more invasive crimson fountaingrass in place of diss inside cement based vegetable concrete. The two plants’ fibres have been characterized by means of electron microscopy, helium picnometry; moreover, the thermal conductivity of fibre panels has been measured. Mortars samples using untreated and boiled fibres have been prepared. The mechanical characterization have been performed by means of three point bending and compression tests. Thermal conductivity and porosity have been measured to characterize physical modification induced by fibres’ treatment. The results showed better thermal and mechanical properties of diss fibres composites than fountaingrass one and that fibres treatment leads to a decrease of thermal insulation properties.

Cork is a unique material, characterized by small closed cell structures, high insulating properties, very low density, high fire resistance and a very good durability after simple thermal treatment. The main use of cork in the production of stopper and insulating panels obtained with cork grains and a polymeric resin. Usually cork grains used in panel production have a grainsize around 1-2 mm. In this work cork grains have been used as aggregates for natural hydraulic lime mortars by reducing grainsize distribution. Cork grainsize has been reduced by means of a knife mill and divided in three different distributions, i.e. 1, 0.5 and 0.25mm. Mortars have been prepared according to NHL to cork to natural sand volume ratio equal to 2:3:2. Three point bending and compression tests showed that reducing cork grainsize leads to a slight increase in mechanical performance. On the other hand thermal conductivity showed to be independent from cork grainsize. Scanning electron microscope investigation was also performed to better understand these results.

In this paper, the potentialities of pumice-based geopolymers have been explored with the aim to evaluate their use as restoration materials. In particular, the behaviour of Aeolian pumice during alkali activation process, either alone or in binary mixtures with metakaolin, has been assessed using sodium hydroxide and sodium silicate activators. Hardened products were characterized by: X-ray diffraction; infrared spectroscopy; thermo gravimetry and electron microscopy. Furthermore, Hg-intrusion porosimetry, water absorption, compressive strength and colorimetric measurements were carried out in order to define the technical features of the produced geopolymers. The results reveal that Aeolian pumice mixed with small quantities (20–30 wt%) of metakaolin is suitable for the formation of lightweight geopolymers which exhibit an accessible porosity up to 30%, water absorption of about 18.0%, and satisfactory 28-day compressive strength up to 12 MPa. These values indicate good breathability and adaptability to the substrates of the proposed formulations. Final products display a homogeneous and compact amorphous matrix, and their colour mimic the original stones, highlighting their potential role in Cultural Heritage preservation.

Anodic films were grown on Weathering Steel by potentiostatic polarization in slightly alkaline solution. The photoelectrochemical results reveal that they are n-type iron oxide with Eg = 2.0 eV. Rust layer grown by atmospheric corrosion are n-type semiconductors with a band gap higher than that estimated for the anodic film attributed to the formation of γ-lepidocrocite. The electrochemical impedance spectra allow to evidence that rust layers have a higher conductivity with respect to anodic films due to the presence of highly doped iron oxide layers. The use of Mott-Schottky theory to model the dependence of oxide capacitance as function of potential is critically discussed.

Coating of flexible substrates is crucial to prepare versatile, multifunctional materials. However, exploration of effective fabrication approaches is still a challenging issue, because the pathways generally proposed require time-consuming, multistep protocols. Here, we developed a one-pot process for decorating either pearl necklace-like or fibrous fluffy-like structures of polycaprolactone (PCL) with graphene oxide (GO) skin. PCL solutions were dry jet-wet electrosprayed or electrospun into a stirred liquid collector constituted by ethanol-containing GO nanoparticles. The stirred liquid collector enables the formation of 3D-structures, whose microarchitecture can be designed by controlling the rheological behavior of PCL solutions. Two molecular weights of PCL were used (45 or 80 kDa) with ensuing different viscosity, which determines the prevalent formation of beads or fibers. The presence of GO in the coagulation bath allows the polymeric structures to be rapidly wrapped by those nanoparticles. Graphenic coating endows these materials with the intriguing peculiarities of GO: PCL/GO nanocomposites displayed increments of elastic modulus ranging from 1250% (beads) to 3300% (fibers) with respect to the neat matrices and a change from hydrophobic to amphiphilic character. A potential application of such devices in water treatment was assessed in phenol removal. The results pointed out that PCL/GO scaffolds retain the same sorption capacity of GO nanoparticles, while bringing several advantages in terms of handling, robustness, and recyclability. The ease of control of the process, as well as its fastness and cost-effectiveness could open a wide range of scenarios, including sensors, energy, catalysis, biomedicine.

In questo lavoro di ricerca, sviluppato all’interno della tesi di laurea magistrale in Conservazione e Restauro dei Beni Culturali presso l’accademia Galli di Como con la supervisione della restauratrice Gisella Bianconi, si è sperimentato l’uso del silicato di litio come additivo per il miglioramento delle prestazioni di malte a base di leganti inorganici, e in particolare calci aeree e idrauliche, utilizzate nel restauro dei materiali lapidei. Spesso per le stuccature di materiali lapidei compatti vengono utilizzate malte con leganti organici, ed in particolare di tipo epossidico, che offrono certamente ottime proprietà meccaniche e un’eccellente adesività, garantendo al contempo una accettabile compatibilità grazie alla bassa porosità del materiale originale, d’altra parte questi materiali non risultano idonei nel caso di materiali caratterizzati da maggiore porosità o con scarsa coesività. In questo lavoro, sono state prese in esame malte sperimentali confezionate con aggregati naturali di diversa litologia e leganti inorganici a base di calce aerea e idraulica, utilizzati tal quali o con l’aggiunta, dopo che si erano completate le fasi di presa e di indurimento, di silicato di litio in nanoparticelle disperse in acqua. Sulla base di un protocollo sperimentale ben progettato sono stati preparati circa 250 campioni di malte, trattate per metà con silicato di litio, e su di esse sono state effettuate le seguenti prove fisiche e meccaniche: determinazione del coefficiente di assorbimento d’acqua per capillaritả secondo la UNI EN 1015-18; la determinazione del contenuto d’acqua di equilibrio secondo la UNI 11086; resistenza alla flessione in accordo con la UNI EN 1015-11; la determinazione della resistenza all’abrasione secondo la UNI EN 14157: 2005. Il confronto tra i risultati ottenuti nelle diverse prove effettuate ha permesso di svolgere un efficace valutazione delle capacità aggregative del silicato di litio e ha permesso di evidenziare le interazioni dell’additivo con il legante e in parte con gli aggregati. In particolare l’aggiunta di silicato di litio ha migliorato considerevolmente le proprietà meccaniche dei materiali testati, modificando in maniera poco evidente le caratteristiche del materiale legate alle interazioni con l’ambiente, come l’assorbimento d’acqua e la capillarità, permettendo di ricavare indicazioni utili per l’uso in pieno campo di questo prodotto nella preparazione di malte da intervento nel campo della conservazione dei beni culturali. È infine risultato di particolare interesse l’incremento ottenuto nella resistenza all’abrasione, che ha permesso di ottenere malte da utilizzare nella stuccatura di materiali lapidei, non solo porosi ma anche compatti, lucidabili e successivamente colorabili mediante colori dispersi nello stesso silicato di litio ad agire come legante. Con questa formulazione è stato realizzato quindi un campione di stuccatura su marmo, ritoccato ad acquerello, con cui è stato possibile ottenere, grazie alle opportune tecniche di reintegrazione pittorica, una perfetta continuità estetica della stuccatura con il materiale originale, una chiara distinguibilità garantita dalla diversa natura materica e un’elevata compatibilità grazie alla natura dei leganti e additivi utilizzati.

We report on the restoration of a XVII century’s predella reliquary, which is a part of a larger setup that includes a wall reliquary and a wooden crucified Christ, both belonging to the church of “Madre Maria SS. Assunta”, in Polizzi Generosa, Sicily, Italy. The historical/artistic and paleographic research was flanked successfully by the scientific objective characterization of the materials. The scientific approach was relevant in the definition of the steps for the restoration of the artefact. The optical microscopy was used for the identification of the wood species. Electron microscopy and elemental mapping by energy-dispersive X-ray (EDX) was successful in the identification of the layered structure for the gilded surface. The hyperspectral imaging method was successfully employed for an objective chemical mapping of the surface composition. We proved that the scientific approach is necessary for a critical and objective evaluation of the conservation state and it is a necessary step toward awareness of the historical, liturgical, spiritual and artistic value. In the second part of this work, we briefly describe the conservation protocol and the use of a weak nanocomposite glue. In particular, a sustainable approach was considered and therefore mixtures of a biopolymer from natural resources, such as funori from algae, and naturally occurring halloysite nanotubes were considered. Tensile tests provided the best composition for this green nanocomposite glue.

Zinc hydroxystannate (ZnSn(OH)6) coatings were deposited on galvanized carbon steel samples by an electroless heterogeneous crystallization process. Structural and morphological features of the coatings as a function of the immersion time were determined by X-ray diffraction, Raman Spectroscopy and Scanning Electron Microscopy revealing the presence of truncated octahedrons of crystalline ZnSn(OH)6. Electrochemical characterization in a simulated concrete pore solution without and with addition of chloride ions proved that the cathodic protection is preserved and that ZnSn(OH)6 improved the corrosion resistance of the rebars. Pull-out tests demonstrated an enhanced bond strength at the rebar/concrete interface and, thus, an improved adhesion after the heterogeneous crystallization process.

The work aim is focused on two different aspects: first, the investigation of the effect of extended ultra-sound-assisted treatment (us) of carbonaceous nanoparticles, such as carbon nanotubes (CNTs) and carbon black (CB), on their radical scavenging activity, and second, the investigation of the oxidative resistance of polymer-based nanocomposites, containing us-treated CNTs and CB. Particularly, the CNTs and CB have been subjected to us sonication for different time intervals and the performed analysis reveals that both kinds of nanoparticles show decreased average hydrodynamic diameters and large content of surface defects. Really, the increased content of CNTs and CB defects, achieved during the sonication time, leads to an increased reactivity toward 1,1-diphenyl-2-pycryl (DPPH) radicals and an enhanced anti-oxidant activity toward macro-radicals, coming from the photo-degradation of the host polymer matrix. The studies of photo-oxidative behavior of the nanocomposites, based on Ultra High Molecular Weight (UHMWPE), reveal that the us treatment of the nanoparticles has a benefic effect on the oxidative resistance of the nanocomposites, especially at long exposure times. Overall, the ultra-sound-assisted treatment can be considered twofold powerful tool: (i) for disruption of the nanoparticles aggregations, and (ii) for capitalization of surface defects, amplifying and tuning in a controlled way the radical scavenging activity of the carbonaceous nanoparticles.

During the last 6 years at the University of Palermo, a group of academics has been involved in a project called “MENTORE” (“Modifying and ENhancing Teaching through peer Observation and Reflections with Experts.”) The objectives of the project are to help teachers improve their teaching, through the help of two mentors; to experiment new approaches in pilot courses to extend, if useful, to other ones; and to change the traditional model of academic teaching based on one single teacher with the class to go toward a model where there is a group of teachers working together in search of improvements. All the participants of the MENTORE project attend to lectures/workshops on teaching and learning and participate in meetings where they share experiences and ideas. In the program, each participant has two mentors who help him or her to improve the quality of his or her teaching. The two mentors are other academics who participate in the program. Indeed, each participant is both mentor and mentee during the same year. Mentors follow some of the lectures of the mentee, meet the students in the final part of the course in order to collect their opinion, and, finally, meet the mentee in order to discuss the actions to carry out for improving the quality of his or her teaching. This chapter describes the aforementioned peer observation practice adopted at the University of Palermo and focuses on the role of mentors describing their activities during the peer observation process.

The use of polymers for conservation of cultural heritage is related to the possibility to slow down or stop natural deterioration which, in many cases, corresponds to stopping the entrance of liquid water and to favour spontaneous water vapour removal. Unfortunately, hydrophobicity is generally favoured by surface roughness and thus competitive with transparency. It is therefore important to find an optimal balance hydrophobicity, transparency and durability (especially to photooxidation). However, polymers typically used for applications in this field come from non-renewable resources and are not biodegradable. In this work, the mechanical, structural and optical properties of PLA, PBAT and a PBAT/PLA blends, as well as surface properties and water vapour permeability, were investigated before and after exposure to UV irradiation, in order to evaluate their durability and suitability for conservation of cultural heritage.

The photocatalytic oxidation of trans-ferulic acid to vanillin in water has been studied by using various TiO2 and WO3-loaded TiO2 samples as catalysts. Different values of selectivity were obtained depending on the physico-chemical properties of the single samples and a vanillin selectivity of 10% was reached in the presence of the commercial TiO2 Merck. Higher selectivity values were obtained by impregnation of TiO2 with H2WO4 followed by calcination. The increased production of vanillin exhibited by the obtained WO3-loaded TiO2 powders was attributed to a reduced further oxidation of the aldehyde caused by the presence of the practically inactive tungsten trioxide hydrate on the TiO2 surface. The best result (ca. 25% of selectivity) was obtained with the WO3(1%)/TiO2 sample.

Strontium titanate-based perovskites have been prepared in the presence of Y and Co with the aim to substitute Sr and Ti, respectively, in the ST crystalline structure. The obtained samples have been characterized by XRD, Raman spectroscopy, FE-SEM, XPS and tested as photocatalysts in two gas-solid regime reactions: (i) 2-propanol complete mineralization and (ii) propene partial oxidation, using a system simulating solar irradiation. All the tested samples resulted active as photocatalysts but with significant differences. The lattice substitution of Sr by Y displays a beneficial effect on the 2-propanol photodegradation. Conversely, the partial presence of cobalt on the ST surface, as Co-oxide nanodispersed clusters with a dominant Co(II) phase, plays a substantial detrimental effect on the photo-degradation process of 2-propanol, but favours the photocatalytic partial oxidation of propene to propene oxide. (c) 2014 Elsevier Inc. All rights reserved.

Binary materials composed of the oxides SiO2, TiO2 and N-doped TiO2 and the Keggin heteropolyacid (PW12) were prepared and physicochemically characterized. They were used as catalysts and photocatalysts for the hydration of propene to 2-propanol. The characterization of the samples, particularly the electron paramagnetic resonance (EPR) spectroscopy results and the acidity properties, were useful to explain the key role played by the PW12 in the composite materials in the thermal and photoassisted catalytic processes. The simultaneous presence of heat and UV light improved the activity of PW12 in the thermal process, and the binary materials showed better (photo)catalytic activities than that of the bare PW12 in almost all cases. For the first time, this work evidenced through EPR spectroscopy that the increase of reactivity under irradiation could be attributed to the ability of photoexcited PW12 to trap electrons, particularly if the PW12 is supported. Moreover, the effect of water on the reactivity was also studied.

Binary materials composed of the oxides SiO2, TiO2 and N-doped TiO2 and the Keggin heteropolyacid (PW12) were prepared and physicochemically characterized. They were used as catalysts and photocatalysts for the hydration of propene to 2-propanol. The characterization of the samples, particularly the electron paramagnetic resonance (EPR) spectroscopy results and the acidity properties, were useful to explain the key role played by the PW12 in the composite materials in the thermal and photoassisted catalytic processes. The simultaneous pres-ence of heat and UV light improved the activity of PW12 in the thermal process, and the binary materials showed better (photo)catalytic activities than that of the bare PW12 in almost all cases. For the first time, this work evidenced through EPR spectroscopy that the increase of reactivity under irradiation could be attributed to the ability of photoexcited PW12 to trap electrons, particularly if the PW12 is supported. Moreover, the effect of water on the reactivity was also studied.

Thermal oxidation of titaniumwas carried out at 350◦C, 450◦C, and 550◦C for 2 h or 12 h.X-rayDiffraction and Raman Spectroscopy suggest that the thermal oxides are scarcely crystallinewhen the annealing temperature is low, while both anatase and rutile are present for high annealing temperature and time. Photoelectrochemical measurements allowed estimation of a bandgap decreasing from 3.35 eV to 3.15 eV with increasing annealing temperature. The impedance spectra confirmed the formation of n-type semiconductors, with an impedance strongly decreasing on going from a reverse bias toward a forward bias regime. TiO2 nanotubes grown by anodizing Ti in NH4F and water containing ethylene glycol solution were annealed at different temperature and for different times. X-ray Diffraction and Raman Spectroscopy proved that rutile is present at the barrier layer beneath the tubular array, while the tubes are mainly constituted by anatase. The incident photon to current conversion efficiency increased by increasing the annealing temperature and time. The impedance spectra recorded under reverse bias regime for thermal planar oxides and for annealed TiO2 NTs are almost coincident, confirming that the predominant contribution arises from the barrier layer beneath the tubular array. Only under forward regime do the tube walls contribute to the measured impedance.

This study reports a method to determine the absolute crystallinity of partly crystalline brookite TiO2 photocatalysts. A natural, a commercial and various home-prepared brookite powders were characterized by X-ray diffraction analysis, Raman spectroscopy, scanning electron microscopy, UV–vis diffuse reflectance spectroscopy and nitrogen adsorption measurements. The absolute crystallinity was calculated from the ratio between the full width at half maximum intensity of the (121) X-ray diffraction peaks of the brookite samples and the (111) peak of CaF2 as internal standard. The photocatalytic activity of the powders was tested employing the photodegradation of 4-nitrophenol as well as the selective oxidation of 4-methoxybenzyl alcohol to 4-methoxybenzaldehyde (p-anisaldehyde) under UV irradiation. The results indicated that crystallinity positively influenced the photooxidation of 4-nitrophenol and 4-methoxybenzyl alcohol but reduced the selectivity toward the synthesis of p-anisaldehyde.