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

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

Characterization of soluble salts on the frescoes by Saturnino Gatti in the church of San Panfilo in Villagrande di Tornimparte (L'Aquila)

During the archaeometric study of the frescoes by Saturnino Gatti in the church of San Panfilo in Villagrande di Tornimparte (L'Aquila), 11 samples of powder and fragments were taken from different panels of the fresco in order to characterize any degradation produced by the presence of salts. The samples were taken in areas where there were evident detachments, exfoliation and saline crystallization (efflorescences). Precisely, 9 samples were taken from panels A, C, D and E and two samples taken from the top part of the vault. The characterization of the samples was performed using two analytical methods such as Ion Chromatography (IC) and FT-IR / ATR infrared spectroscopy. Ion chromatography was used for the quantification of the main ions and to evaluate the presence of soluble salts. Measurements of cationic (Na+, K+, Ca2+, Mg2+ and NH4+) and anionic (NO3-, SO42-, Cl-) species were performed using an ICS-1000 HPLC system equipped with a conductivity detector. The anion analysis was performed with a column of Ion Pac AS14A using Na2CO3 8 mM/NaHCO3 1mM, flow rate = 1.5 mL/min and for the detection a conductivity system equipped with anionic self-healing suppression ULTRA (ASRS-ULTRA). While, the determination of the cations was carried out using a CS12A column (Dionex) and 20mM of methanesulfonic acid (MSA) as eluent at a flow rate = 1.5 mL/min and for the detection a conductivity system equipped with an ULTRA self-healing cationic suppressor (CSRS-ULTRA). Infrared spectroscopy has been used to characterize the mineralogical phases. The apparatus used is a Nicolet 380 (Thermo Electron Corporation) instrument coupled with ATR accessory Smart Orbit equipped with a diamond crystal. The spectra have been acquired in the range 500-4000cm−1 at a resolution of 4cm−1. The results indicate that some, but not all, samples show high concentrations of sulfate and calcium, attributable to probable efflorescence consisting of newly formed gypsum. Furthermore, a good correlation between sodium and chloride was observed, indicating the presence of an efflorescence composed of newly formed sodium chloride. The calcite and silicate bands attributable to the substrate were observed by FT-IR and also gypsum bands were highlighted confirming what observed by the IC technique

A multi-analytical survey for the identification of the red and yellow pigments of coloured sherds discovered in the Monte d’Oro area (Rome)

The aim of the study was the characterisation of the pigments utilised on the painted sherds found during an excavation performed by the Soprintendenza Archeologica and just approximately assigned to a historical period between the first century B.C. and the first century A.D. The analytical survey here presented meant to provide archaeologists with useful information on the painting materials to better contextualise the findings from an artistic and historical point of view. The investigation procedure comprehended the use of SEM-EDX technique and Raman, infrared and visible reflectance spectroscopies, paying most attention to portable instrumentation diagnostic performances. The study carried out on a selection of the red, and yellow sherds highlighted the presence of cinnabar, litharge, red and yellow ochre also blended among themselves or possibly utilised overlapping more painting layers. Furthermore, it is to notice the presence of gold decorations on some fragments that denotes certain care for details and opulence in the adornment

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