A Cellular Automata Model for Simulating Pyroclastic Flows and First Application to 1991 Pinatubo Eruption

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Multifunctional TiO2 coatings for Cultural Heritage

Environmental pollution arising from industrial implants and urban factors is constantly increasing,causing aesthetical and durability concerns to urban structures exposed to the atmosphere.Nanometric titanium dioxide has become a promising photocatalytic material owing to its ability tocatalyze the complete degradation of many organic contaminants and environmental toxins.This work deals with the preparation system that could take advantage of functionalized buildingmaterials in order to improve the quality of urban surfaces, with particular regard to Cultural Heritage.TiO2-containing photoactive materials represent an appealing way to create self-cleaning surfaces, thuslimiting maintenance costs, and to promote the degradation of polluting agents. Titanium dioxide dispersedin polymeric matrices can represent a coating technology with hydrophobic, consolidating andbiocidal properties, suitable for the restoration of building stone materials belonging to our CulturalHeritage. Mixtures were tested on marble and limestone substrates. Capillary water absorption, simulatedsolar aging, colorimetric and contact angle measurements have been performed to evaluate theirproperties

LLUNPIY Simulations of the 1877 Northward Catastrophic Lahars of Cotopaxi Volcano (Ecuador) for a Contribution to Forecasting the Hazards

LLUNPIY (lahar modeling by local rules based on an underlying pick of yoked processes, from the Quechua word “llunp’iy“, meaning flood) is a cellular automata (CA) model that simulates primary and secondary lahars, here applied to replicate those that occurred during the huge 1877 Cotopaxi Volcano eruption. The lahars flowing down the southwestern flanks of the volcano were already satisfactorily simulated in previous investigations of ours, assuming two possible different triggering mechanisms, i.e., the sudden and homogeneous melting of the summit ice and snow cap due to pyroclastic flows and the melting of the glacier parts hit by free-falling pyroclastic bombs after being upwardly ejected during the volcanic eruption. In a similar fashion, we apply here the CA LLUNPIY model to simulate the 1877 lahars sprawling out the Cotopaxi northern slopes and eventually impacting densely populated areas. Our preliminary results indicate that several important public infrastructures (among them the regional potable water supply system) and the Valle de Los Chillos and other Quito suburban areas might be devastated by northward-bound lahars, should a catastrophic Cotopaxi eruption comparable to the 1877 one occur in the near future

Nano-TiO2 coatings for cultural heritage protection: The role of the binder on hydrophobic and self-cleaning efficacy

Nano-sized titanium dioxide has demonstrated its efficiency in many application fields thanks to its pho-tocatalytic features that provide self-cleaning properties to the materials with simple and non-expensiveprocedures. For this reason, it has been successfully used also for the practice of restoration of stone builtheritage. However, some aspects are still unresolved and need to be further investigated, such as themethod for binding these particles to stone surfaces.In this work, nano-TiO2was combined with three different binders and applied on two stone substrates,namely the Carrara marble and the Noto calcarenite, two lithotypes extensively used in built heritage.The performance of all tested coatings was evaluated by scanning electron microscopy (SEM), roughnessmeasurements, capillary water absorption test, static contact angle calculation, colorimetric measure-ments, UV aging and self-cleaning test. Results suggested the key role of interaction between coating andstone surface in terms of penetration of the product, hydrophobicity, variations of surface roughness anddurability, which define the performance of the coatings. Specifically, among the three tested products,the best behaviour in terms of hydrophobicity, durability and self-cleaning properties was shown by boththe acrylic (Fosbuild) and fluorinated (Akeograd P) suspensions. Conversely, the Paraloid id B72 - TiO2mixture led to an intense superficial alteration of both stones and showed scarce water-repellent andphoto-degrading effect

Cappadocian ignimbrite cave churches: stone degradation and conservation strategies

The focus of this research is to investigate the minero-petrographic features and the conservation aspects of the stone materials from some rock-hewn churches in Cappadocia region (Turkey) in order to choose the most appropriate consolidating systems to improve the resistance against the weathering and degradation phenomena of this unique world heritage site. In this study, specimens from the Tokalı church in the Göreme’s Open Air Museum, and from the Forty Martyrs Church in Şahinefendi were analysed by optical microscopy and Xray diffraction in order to examine the properties of the rock and especially how well preserved it is. The ignimbrite samples show a porphyritic structure with vitrophyric groundmass and crystalloclastic-vitrophyric texture. The presence of smectite and illite caused serious damage to the rock structure such as cracks, decohesion, exfoliation, and disaggregation phenomena. The consolidation tests were performed on the ignimbrite specimens, sized according to the standard procedure, by using three commercial silica-based products: NanoEstel, Estel 1000, and Estel 1100. The consolidant penetration was investigated by titanium labelling procedure followed by scanning electron microscopy-energy dispersive spectroscopy analysis. Colour measurements were used to study the possible chromatic changes due to the treatments. The capillary test was performed to evaluate the amount of water absorbed by the stone surfaces before and after the consolidating treatments. Lastly, the surface cohesion due to the consolidation was investigated by using the peeling test carried out on untreated and treated samples.The consolidating tests showed that the solvent-based products (Estel 1000, Estel 1100) exhibit a better distribution than the aqueous suspensions (NanoEstel). Nevertheless NanoEstel gives better results in the capillary absorption test, suggesting that this product has the ability to leave the stone porous structure substantially unaltered

Marine Antifouling for Underwater Archaeological Sites: TiO2 and Ag-Doped TiO2

Marine fouling plays a crucial role in the degradation of underwater archaeological sites. Limitation of fouling activity and its damages are one of the most critical issues for archaeologists and conservators. The common cleaning procedure, consisting in the manual removal of fouling, requires a continuous maintenance, while a proper inhibition of biological colonisation would provide a long-time protection against biofouling. On the other hand, the most used antifouling paints, especially for ship hulls, show considerable toxicity level. Since submerged archaeological sites are often included in environmental protected areas, more eco-friendly products must be used. We have explored the possibility to use titanium dioxide and Ag-doped titanium dioxide as antifouling agents. For this purpose, they have been synthetized by sol-gel method, and then XRD, XPS, and reflectance spectroscopy measurements have been carried out to gain structural information. The powders have been dispersed in a polymer and then applied to marble surface to evaluate the chromatic alteration induced by the treatments. By means of biological tests, it was possible to assess their behaviour as biofouling agents. Results show a decreasing of biofouling activity on treated stony surfaces

Defining high-detail hazard maps by a cellular automata approach: application to Mount Etna (Italy)

The individuation of areas that are more likely to be affected by new events in volcanic regions is of fundamental relevance for the mitigation of the possible consequences, both in terms of loss of human life and material properties. Here, we describe a methodology for defining flexible high-detail lava-hazard maps and a technique for the validation of the results obtained. The methodology relies on: (i) an accurate analysis of the past behavior of the volcano; (ii) a new version of the SCIARA model for lava-flow simulation (based on the macroscopic cellular automata paradigm); and (iii) high-performance parallel computing for increasing computational efficiency. The new release of the SCIARA model introduces a Bingham-like rheology as part of the minimization algorithm of the differences for the determination of outflows from a generic cell, and an improved approach to lava cooling. The method is here applied to Mount Etna, the most active volcano in Europe, and applications to land-use planning and hazard mitigation are presented

Non-Destructive Multi-Analytical Approach to Study the Pigments of Wall Painting Fragments Reused in Mortars from the Archaeological Site of Pompeii (Italy)

During the excavations carried out in Via di Mercurio (Regio VI, 9, 3) in Pompeii, in 2015, some red, green, black, and brown wall painting fragments were found in the preparatory layer of an ancient pavement which was probably built after the 62 AD earthquake. These fragments, derived from the rubble, were used as coarse aggregate to prepare the mortar for building the pavement. The wall painting fragments are exceptionally well preserved, which is an uncommon occurrence in the city of Pompeii. However, as they were enclosed in the mortar, the wall painting fragments were protected from the high temperatures (probably ranging between 180 °C and 380 °C) produced by the eruption in 79 AD. The pigmented outer surface of each sample was analyzed using a non-destructive multi-analytical approach, by combining spectrophotometric colorimetry and portable X-ray fluorescence with micro-Raman spectroscopy. The compositional characterization of the samples revealed the presence of cuprorivaite, goethite, and celadonite in the green pigments; hematite in the red pigments; goethite in the brown pigment; and charcoal in the black pigment. These data probably provide us with the most “faithful picture” of the various red, green, black, and brown pigments used in Pompeii prior to the 79 AD eruption