A multi-analytical approach to assess the impact of air pollution on cultural heritage : degradation of stones, mortars and bricks

Air pollution is one of the most important causes of surface decay in urban environment. Among the degradation processes due to airborne pollutants, the formation of black crusts is one of the most dangerous one. Currently, emissions from mobile combustion sources are the main agents responsible for pollution, although a significant decrease is expected in Europe within the next decade. The surfaces of architectural heritage in urban environment are exposed to degradation due to the interaction with atmospheric pollutants both in gaseous and in the particulate phase. Monuments located in the historic centres of large cities are subjected to typical anthropogenic emissions. The precise identification of the main substances responsible for the surface degradation phenomena, in particular leading to blackening, erosion of carbonatic matrices and disintegration, is essential for the definition of conservative intervention and maintenance strategies, as well as for the development of emission reduction policies on a larger scale. Black crusts and substrate (stones, mortars or bricks) specimens have been sampled in Milan and Monza from monuments of historical interests and analyzed by a multi-analytical approach including FT-TIR spectroscopy, ion chromatography (IC) and electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). The characterization of the carbon fraction (organic carbon, OC, and elemental carbon, EC) was performed using a new approach based on a thermal protocol and on the use of CHN analysis and thermogravimetric analysis (TGA). This integrated approach has been already applied in some case studies [1-4]. Data acquired on the specimens have been compared with those collected by the regional environmental protection agency (ARPA Lombardia) in order to assess, also through the use of dose-response functions, the degradation phenomenon that occur

The effects of air pollution on cultural Heritage : the case study of Santa Maria delle Grazie al Naviglio Grande (Milan)

Atmospheric pollution causes monuments surface degradation in urban environments. Among the degradation processes the formation of black crusts (BCs) is one of the most dangerous phenomenon. During this process, aerosol particulate matter (PM) can be embedded into gypsum, one of the main crusts constituents, providing the characteristic black colour. EC (elemental carbon) and OC (organic carbon) are the responsible for the yellowing and blackening processes occurring on the surfaces and their quantification in the crusts can provide information on the contribution of atmospheric pollution sources to the degradation products formation. This research study is focused on the characterization of BCs collected from the Church of Santa Maria delle Grazie al Naviglio Grande in Milan, from the point of view of the effects of atmospheric pollution on cultural heritage. The analysed samples consist of mortars and bricks partially degraded and covered with black crusts. Appling different analytical techniques, such as FTIR/ATR, CHN, TGA and IC, the crusts composition has been investigated focusing on the quantification of the carbonaceous fraction. This integrated approach has allowed to identify the sources of pollution responsible for the decay of the different building materials of the church

Marble hydrophobicity tuned by Si-based coatings

Hydrophobic polymers applied on stone materials increase their durability against undesired weathering processes [1]. The achievement of a certain degree of surface hydrophobicity (reducing the water permeation) constitutes one of the main research focuses [2]. Herein, two commercial Si-based resins (e.g. Alpha\uaeSI30 and Bluesil\uaeBP9710), directly applied on Carrara marble substrates and a silanization process, by using trichloromethylsilane (TCMS), were adopted. Contact angle measurements were carried out to evaluate the hydrophobic features. Hence, since only in the case of TCMS a good hydrophobicity was achieved (\uf071 around 150\ub0), two commercial polysiloxane-based additives (e.g. TegoPhobe 1500N and TegoPhobe 1650) were added respectively to Alpha\uaeSI30 and Bluesil\uaeBP9710, according to their chemical compatibility. These auxiliary substances allowed to decrease the wettability features of marble. Furthermore, since all the investigated coatings could be used as stone materials protective agents, water capillary absorption and vapor permeability tests were performed. Also, in this case, TCMS revealed to be the most performing one among the adopted silane-based resins, thanks to the drastic reduction of absorbed water and the decrease of vapor permeability within the threshold value of 50%. Finally, the coatings stability was evaluated by accelerated ageing tests. References [1] Cappelletti G., Fermo P., Pino F., Pargoletti E., Pecchioni E., Fratini F., Ruffolo S.A., La Russa M.F., On the role of hydrophobic Si-based protective coatings in limiting mortar deterioration, Environ Sci Pollut Res, 22 (2015) 17733\u201317743. [2] Cappelletti G., Fermo P., Camiloni M., Smart hybrid coatings for natural stones conservation, Progress in Organic Coatings 78 (2015) 511\u2013516

A TGA/FT-IR study for OC and EC quantification applied to carbonaceous aerosol collected in Milan (Italy)

International audienceCarbon analysis consists in the evaluation of the carbonaceous content of the aerosol (TC) but, more importantly, of its distribution between the two components EC (Elemental Carbon) and OC (Organic Carbon) that are characterized by different physical-chemical properties. In spite of the numerous studies focused on this topic, nowadays, a universal methodology for the determination of the two components EC and OC is not available. In fact OC and EC (also known as black carbon or soot) are operationally defined by the method of analysis and, as a consequence, different methods can produce different results. In this paper we present results on the application of TGA/FT-IR (Thermogravimetric Analysis/Fourier Transformed Infrared Spectroscopy) to the characterization of carbonaceous aerosols. The analytical methodology was applied to PM10 four-hour time resolution samples collected in Milan urban area. The method is a two-steps thermal one and bases itself on the different thermal behaviour of OC and EC. It has been set up analyzing suitable standards containing both organic and elemental carbon. Carbon quantification is achieved by on-line, continuous monitoring of CO2 infrared absorption at 2361 cm?1. A good separation between OC and EC on particulate matter samples has been obtained. Ranges and average values were respectively 12?70 µg/m3 and 20 µg/m3 for OC and 0.2?6 µg/m3 and 2 µg/m3 for EC. On average OC and EC made up respectively 29.3 (±12.8) % and 2.5 (±1.8) % of PM10 fraction. The method reliability has been verified by comparison with TOT (Thermal Optical Transmission) technique. OC and EC values determined for ambient samples of PM10 were also correlated with meteorological parameters as well as with Radon concentrations

Artificial neural networks for 3D cell shape recognition from confocal images

We present a dual-stage neural network architecture for analyzing fine shape details from microscopy recordings in 3D. The system, tested on red blood cells, uses training data from both healthy donors and patients with a congenital blood disease. Characteristic shape features are revealed from the spherical harmonics spectrum of each cell and are automatically processed to create a reproducible and unbiased shape recognition and classification for diagnostic and theragnostic use.Comment: 17 pages, 8 figure

Efficiency of an Air Cleaner Device in Reducing Aerosol Particulate Matter (PM) in Indoor Environments

Abstract: Indoor air quality (IAQ) in household environments is mandatory since people spend most of their time in indoor environments. In order to guarantee a healthy environment, air purification devices are often employed. In the present work, a commercial household vacuum cleaner has been tested in order to verify its eciency in reducing the mass concentration and particle number of aerosol particulate matter (PM). The eciency has been tested measuring, while the instrument was working, PM10 (particles with aerodynamic diameter less than 10 m), PM2.5 (particles with aerodynamic diameter less than 2.5 m), PM1 (particles with aerodynamic diameter less than 1 m), and 7 size-fractions in the range between 0.3 and >10 m. Measurements have been carried out by means of a portable optical particle counter instrument and simulating the working conditions typical of a household environment. It has been found that the tested commercial device significantly reduces both PM concentrations and particle number, especially in the finest fraction, i.e., particles in the range 0.3\u20130.5 m, allowing an improvement of indoor air quality

The hydrophobicity modulation of glass and marble materials by different Si-based coatings

Hydrophobic polymers applied on hydroxylated surfaces increase their durability against undesired weathering processes. The achievement of a certain degree of surface hydrophobicity (reducing the water permeation) constitutes one of the main research focuses. Herein, two commercial Si-based resins (e.g. Alpha\uaeSI30 and Bluesil\uaeBP9710), directly applied on both glass and Carrara marble substrates, and a silanization process by using trichloromethylsilane (TCMS) were adopted. Contact angle measurements together with hysteresis determination and Surface Free Energy (SFE) were carried out to evaluate the hydrophobic features. Hence, since only in the case of TCMS a good hydrophobicity was achieved (\uf071 around 150\ub0), two commercial polysiloxane-based additives (e.g. TegoPhobe 1500N and TegoPhobe 1650) were added respectively to Alpha\uaeSI30 and Bluesil\uaeBP9710, according to their chemical compatibility. These auxiliary substances allowed to decrease the wettability features of either glass or marble. Furthermore, since all the investigated coatings could be used as stone materials protective agents, water capillary absorption and vapor permeability tests were performed. Also in this case, TCMS revealed to be the most performing one among the adopted silane-based resins, thanks to the drastic reduction of absorbed water and the decrease of vapor permeability within the threshold value of 50%. Finally, the coatings stability was evaluated by accelerated ageing tests