Search

The introduction of "deep learning" algorithms for feature identification in digital imaging has paved the way for artificial intelligence applications that up to a decade ago were considered technologically impossible to achieve, from the development of driverless vehicles to the fully automated diagnostics of cancer and other diseases from histological images. The success of deep learning applications has, in turn, attracted the attention of several researchers for the possible use of these methods in chemometrics, applied to the analysis of complex phenomena as, for example, the optical emission of laser-induced plasmas. In this paper, we will discuss the advantages and disadvantages of convolutional neural networks, one of the most diffused deep learning techniques, in laser-induced breakdown spectroscopy (LIBS) applications (classification and quantitative analysis), to understand the real potential of "deep LIBS" in practical everyday use. In particular, the comparison with the results obtained using "shallow" artificial neural networks will be presented and discussed, taking as a case study the analysis of six bronze samples of known composition. (Figure presented.).

The church of San Francesco del Prato in Parma (Italy) is a masterpiece of the Gothic style, dated back to the 13th century. However, its historical and monumental value could not be appreciated for a long time, especially due to the transformation of the building into a city jail. The recent restoration works brought back to light valuable frescos and wall paintings belonging to different periods. An in situ campaign was performed on the 15th-century wall paintings adorning the vault and the walls in the church apse, by using mobile Raman and X-ray fluorescence equipment. The characterization of the art pieces was further carried out with micro-Raman spectroscopy and gas chromatography–mass spectrometry analyses. Overall, a quick and thorough identification of the colours palette of the wall paintings was successfully obtained through the in situ measurements. Laboratory analyses corroborated the understanding of the techniques through the identification of pigments and binders. In addition, micro-Raman analyses highlighted the presence of degradation products. Interestingly, a pigment hierarchy has been noted in relation to the painted contents, enhancing the preciousness of holy figures and their distinctive details.

Preface

The knowledge of the spectroscopic parameters of the elemental emission lines is important for diagnostics of laser-induced plasmas and the application of calibration-free/fundamental parameters analytical methods. In this paper, we used the recently proposed time-independent extended C-sigma method for determining, for the first time, the transition probabilities and Stark broadening coefficients of several neutral (TIECS) and ionic silver emission lines. The method allows for a compensation of self-absorption in the plasma, thus providing a measure of the spectroscopic parameters which is not affected by the optical thickness of the plasma.

Street art murals are an artistic expression strictly interwoven in the urban landscape, and in recent years have received increasing attention as cultural heritage at risk. Today there is intense debate regarding the value assessment and choices related to the conservation of urban art; however, the evaluation of the stability of modern paint materials in outdoor environment is preliminary to any possible preservation strategy. In particular, the identification of the materials constituting a street artwork is critical for the preservation of these non-permanent heritage elements and to define the best restoration approaches. In this work, we performed a set of analyses of microsamples based on spectroscopy, analytical pyrolysis, gas and liquid chromatography, and mass spectrometry to identify paint materials (binders, pigments, additives, degradation products and conservation/restoration materials) of a selection of mural paintings, covering 60 years of history (1953–2014). The goal of this work was to identify the materials used to produce different mural paintings and to relate and compare their different compositions with previous studies in order to describe the evolution of the materials during the last 60 years. The collected knowledge and the limited data available in literature were exploited to increase the scientific background on the materials used by street artists, and to fill the lack of knowledge on this emerging topic.

One of the most hotly debated subjects in lutherie circles is the composition of the finishing layers applied by the violinmakers of the past on their valuable bowed string instruments. These are often composed of several organic and inorganic materials, variously mixed and overlaid. During the last decade many analytical strategies were put in place in order to correctly identify these materials. The most used are surely non- and micro-invasive spectroscopic techniques (e.g. XRF, EDX, FTIR) integrated, when possible, with the imaging and tomographic ones with a multi-analytical approach. In this work, Laser-Induced Breakdown Spectroscopy (LIBS) and Optical Coherence Tomography (OCT) were tested together on laboratory mockups and historical bowed string instruments in order to identify and characterize the materials composing the finishing layers of these selected artworks.

This research is part of a wider scientific Italian-Indo project finalised to shed lights on pottery fabrication and trade circulation in Tamil Nadu region during Early Historical Period. The recent archaeological excavations carried out in Alagankulam—a famous harbour trading with the eastern and western world—and in Keeladi—the most ancient civilization centre attested in Tamil Nadu region—provided numerous fragments of archaeological ceramics. The typological analysis enabled the identification of different pottery classes, suggesting the presence of local productions, possible imports and imitations. Studied shards included common Indian vessels, fine wares and luxury ware repertoire. The provenance identification of some of the studied typologies is still debated in the literature; for long time, the misattribution of several ceramic classes has led to wrong interpretations on the commercial connections between India and the Western and Eastern Mediterranean area. The minero-petrographic and spectroscopic investigation of several ceramic fragments from the two investigated archaeological sites enabled the systematic compositional characterization of specific ceramic classes both locally manufactured and imported. The obtained results contributed to draw short-range and long-range connections in Tamil Nadu area.

The Attirement of the Bride, painted by Max Ernst in 1940, is permanently on display in the Peggy Guggenheim Collection (PGC) in Venice. Within the framework of a larger study of materials and techniques of works by Ernst at the PGC, researchers carried out a series of non-invasive analyses. A combined approach based on Vis-NIR multispectral imaging, Raman Spectroscopy, X-Ray Fluorescence (XRF), and External Reflection Fourier Transform Infrared Spectroscopy (ER-FTIR), was conducted insitu in the museum galleries. In addition, two micro-samples were analysed with SEM-EDS and μ-Raman. This approach produced vital information on the preparatory drawing, the pentimenti, the pigments, the extenders and the alteration products present in the painting. The results showed also the presence of a white preparatory layer, under the pictorial one and above the canvas, composed by lithopone (a mixture of zinc sulphide and barium sulphate), basic lead carbonate and calcium carbonate. The latter compound is probably present also as an extender. The palette included both traditional and new synthetic, commercial pigments, used as primary colours or in mixtures. Moreover, in several areas of the painting, zinc oxalates have been identified as alteration products and more rarely, zinc metal soaps, which could also be present as additives in the paint tube. These analyses revealed the masterful and innovative painting technique of this pioneer of Surrealism.

In the context of scientific visualization, the main challenge is to achieve a good balance between the accurate representation of scientific data (computed or stored in databases) and the visual quality of the virtual experience itself. Traditional scientific software relies on custom tools meant to be used on conventional terminals or software developed with mouse and keyboard in mind. However, the true advantage of Virtual Reality is the enhanced ability of finding connections between apparently heterogeneous information, discovering correlations that would otherwise be harder to detect. In particular, in the field of Digital Humanities, it is increasingly necessary to develop and validate virtual reality tools that are capable of combining various scientific data in a Virtual Reality context with access and consultation of online repositories. This paper reports the main aspects of the implementation of a heterogeneous relational database available online storing 3D models, metadata and chemical analyses related to different sectors of digital humanities. The Virtual Reality software, called PROTEUS, allows the user to shrink himself from the macroscopic world of Digital Humanities, down to the microscopic world of molecular sciences. The web platform is connected to the virtual reconstruction software, which dynamically loads the information available in the online repository within the virtual reality application. This application also provides a detailed explanation of the reconstruction of the 3D models for the various objects, and the chemical analyses. The real advantage of a virtual reality application is the real time interaction with data and 3D models, thus allowing the researcher to understand and manipulate objects, to test hypotheses and to seek meaningful results, visualizing the metadata while changing the parameters of the simulation in a dynamic and interactive way. This is a significant step forward in the democratization of science, by means of an user friendly and immersive access to advanced scientific algorithms, and the integration of the Proxima Molecular Perception library, which allows the automatic perception of structural and topological features of the underlying molecular and supra-molecular systems.

In this work, a solid phase microextraction procedure, denoted as Thin Film Microextraction (TFME), was combined with Laser-induced Breakdown Spectroscopy for the detection of several analytes in aqueous solutions (Cu, Cr, Ni and Pb). The adsorbent films, consisting of a thin layer of graphene oxide deposited on glass substrates, were generated by using the electrospray deposition technique (ESD). Several parameters affecting the quality and shape of the films resulting from the ESD process were studied, and the morphology and adsorption capacity of the films were evaluated. The generated films were used for extraction of the target analytes from aqueous solutions and, after extraction, the analytes-enriched adsorbents were analysed by LIBS without the need of any desorption or elution step. In order to assess the analytical capability of the TFME-LIBS procedure, different analytical figures of merit of the proposed TFME-LIBS methodology were evaluated. The obtained limits of detection were 14 μg kg−1 for Pb and 15 μg kg−1 for the rest of the tested analytes. Measurement repeatability was better than 4% RSD at low concentration level (20 μg kg−1) but deteriorated by increasing the concentration level at 100 μg kg−1, with %RSD ranging from 3.6% (Cr) to 24% (Pb). Method trueness, evaluated from the analysis of a real sample of bottled water, led to recovery values in the range 85%–106%. This work was supported by the Spanish Ministry of Economy and Competitiveness [CTQ2016-79991-R], the Regional Government of Valencia (Spain) [PROMETEO/2013/038 and PROMETEO/2018/087]; and the University of Alicante [UAUSTI17-04 and UAUSTI18-04]. L. Ripoll is grateful to the Ministry of Economy and Competitiveness for her PhD fellowship (FPI-MICINN (BES-2012-058759)).

Exfoliated black phosphorus (bP) embedded into a polymer is preserved from oxidation, is stable to air, light, and humidity, and can be further processed into devices without degrading its properties. Most of the examples of exfoliated bP/polymer composites involve a single polymer matrix. Herein, we report the preparation of biphasic polystyrene/poly(methyl methacrylate) (50/50 wt.%) composites containing few-layer black phosphorus (fl-bP) (0.6–1 wt.%) produced by sonicated-assisted liquid-phase exfoliation. Micro-Raman spectroscopy confirmed the integrity of fl-bP, while scanning electron microscopy evidenced the influence of fl-bP into the coalescence of polymeric phases. Furthermore, the topography of thin films analyzed by atomic force microscopy confirmed the effect of fl-bP into the PS dewetting, and the selective PS etching of thin films revealed the presence of fl-bP flakes. Finally, a block copolymer/fl-bP composite (1.2 wt.%) was prepared via in situ reversible addition–fragmentation chain transfer (RAFT) polymerization by sonication-assisted exfoliation of bP into styrene. For this sample, 31P solid-state NMR and Raman spectroscopy confirmed an excellent preservation of bP structure.

A multi-analytical study was carried out on an ancient Egyptian limestone stele with red figures and hieroglyphs (S. 6145) coming from the village of Deir el-Medina and belonging to the collection of the Museo Egizio (Turin, Italy). With the support of a multidisciplinary team, a project for the preservation and conservation of this stele provided an opportunity to carry out a very detailed study of the object. Petrographic and mineralogical analysis led to the characterization and dating of the limestone, and ultrasonic tests were of great help in shedding light on the state of preservation of the stele, as a preliminary to planning conservation treatment. The chemical nature of the red pigment was investigated by non-invasive spectroscopic analyses. Multispectral imaging and statistical image processing improved the readability of the hieroglyphs, whose preservation ranged from heavily compromised to almost completely invisible, revealing some signs that had previously not been visible.

Laser-Induced Breakdown Spectroscopy (LIBS) micro-mapping is an important analytical tool for the study of geomaterials. In this work, this technique was applied, for the first time, to the analysis of alkali-activated materials and geopolymers, as well as rocks, mortars and bricks. The results obtained were compared with the ones obtained using Energy-Dispersive X-Ray Fluorescence (ED-XRF) macro-mapping and the advantages of the LIBS approach (speed, lateral and in-depth resolution, capability of light elements analysis) were highlighted. The issues associated with the quantitative determination of the samples' composition from the analysis of the LIBS spectra were also briefly discussed.

Graphical abstract, Highlights • Characterization of LIP by the Columnar Density Saha-Boltzmann (CD-SB) plot. • Use of strongly self-absorbed lines to calculate the plasma temperature. • Temporal evolution of the plasma temperature by CD-SB plot. • CD-SB plot as a promising method to obtain plasma temperature at later times. • CD-SB plot does not require the calibration of the detection system., In exploiting the analytical capabilities of plasma-based spectroscopy method, the evaluation of plasma parameters, particularly the plasma temperature, is a crucial step. In this work, a modified Saha-Boltzmann plot, which uses the columnar densities of atomic and ionic ground levels, is utilized to calculate the plasma temperature in a laser-induced plasma from an aluminum alloy target. The columnar densities are here calculated by quantifying the self-absorption of resonance lines. It is demonstrated that this is a promising method for accurate determination of plasma temperature. To validate the capability of this technique, plasma emission is measured at different gate delay times. For each delay, excitation temperature is calculated both by the conventional Saha-Boltzmann plot (by using the excited states) and by exploiting the new Columnar Density Saha–Boltzmann (CD-SB) plot. The results suggest that at later times of the plasma evolution, the CD-SB plot can be more suitable for the determination of plasma temperature than conventional Saha-Boltzmann plot. These findings provide a new approach for physical characterization of plasmas and give access to a wealth of information about the state of plasma.

This paper deals with the stones used as building materials in the centre of Pisa during the Middle Age. Most of the stones are quarried from the nearby mountains, Monte Pisano and Monti d’Oltre Serchio, but there are also other ones, coming from Apuan Alps, Elba Island, western Tuscan coast, and from other quarries opened in the Western Mediterranean area. Our goal is to enrich the classic concept of street photography by inserting, in an interpretative context, the analysis and the observation of the geoenvironment in which we are immersed, daily, for the journey home-office, home-school or just for a simple walk. The tools we have are the eyes, the light and an instrument: the camera. Five stops along a city route allow to describe the main types of stones that have been used to construct and ornate the buildings since the 10th and 11th centuries, when Pisa acquired its traditional fame as one of the four historical Maritime Republics of Italy. Monte Pisano marble is the most important stone in the medieval phase of construction of the city of Pisa, often used together with black limestones to give the typical decorative alternate bands, black and white, of the Pisan Romanesque style. Other types of stones were also used, such as Quartzites, Agnano breccia, Panchina, Macigno sandstone as well as Apuan marble, granitoid rocks from Elba Island and Sardinia, and some rocks from ancient quarries of the western Mediterranean area, such as precious marbles from Greece and Turkey.

In this work, we report the results on the application of Laser-Induced Breakdown Spectroscopy (LIBS) to the analysis of coal, for the determination of its Ash Content. This parameter is critical for an efficient use of coal to produce electrical energy in power plants. The results obtained are compared with the ones obtained through conventional chemical laboratory analysis. The study here presented, although performed in the Laboratory, was set up trying to reproduce the real industrial conditions, with the purpose of easing the transfer of the results obtained to the on-line monitoring of coal quality at the power plant.

Trichrome painted wares spread out during the Middle Neolithic (between 5000 and 4500 cal. BC) along the Adriatic side of the Italian Peninsula. The pottery production was characterized by a very fine-granulated paste defined figuline and by a decoration painted with red and black colors. This research reports the results of X-Ray Fluorescence (XRF) and micro-Raman spectroscopy analysis focused on the decoration of the ceramics from two distinct geographical groups, corresponding to the village of Ripoli (Abruzzo, Central Italy) and to the Matera's caves (Basilicata, Southern Italy). A representative set of samples has been studied. XRF and micro-Raman analyses reveal that the black decoration was obtained using a black pigment based on manganese-iron oxide, whereas the red one includes iron oxides. To investigate the multilayer structure of the samples, a Monte Carlo simulation has been performed on the XRF data. The results, together with the data achieved on samples of the Serra d'Alto Culture from Matera's sites, allow to confirm previous hypotheses on the figuline production. In particular, a technological evolution is proven by the selection and control of the raw materials associated to a technologically advanced firing system. The choice of a manganese pigment is a further technological connotation of figuline potteries.

In this paper, we present a critical review on the applications of the Laser-Induced Breakdown Spectroscopy (LIBS) technique in cultural heritage and archaeology. The strategies used by the groups involved in this kind of research for the analysis of the typical materials of interest (metals, pigments, pottery, glass, etc.) are discussed in detail, as well as the use of LIBS in combination with other techniques (LIBS and Raman, LIBS and XRF, and LIBS and MS). Specific applications of LIBS as a support for cultural heritage restoration and the application of the technique for the analysis of underwater objects are presented in separate sessions. In conclusion, new trends of LIBS for cultural heritage and archaeology (micro-LIBS analysis, 3D elemental imaging, and surface- and nanoparticle-enhanced LIBS) are introduced and discussed.

3D multi-band/multi-spectral reconstruction is a technique, which allows the use of images taken in different spectral bands for the reconstruction of spectrally-resolved 3D models of paintings. In this work, we propose a procedure for constructing and comparing 3D multi-band models obtained starting from a variety of input data (RGB and IR images, UV-induced fluorescence images, etc.) and/or acquired with different instruments. The procedure has been tested on two case studies, with the aim to highlight the critical issues associated to the specificities of the subject and of the environmental constrains: a 14th century panel painting signed by Barnaba from Modena, preserved at the Museum of San Matteo in Pisa, Italy and a 15th century panel painting preserved at the Regional Gallery of Palazzo Bellomo in Syracuse, Italy. RGB, IR and UV–VIS fluorescence models obtained with a conventional digital camera (RGB and UV) and a multisband camera (IR) were realized and compared, for revealing differences at sub-millimeter level.

This paper presents the study of various Roman materials used in the construction of the Maritime Theatre, one of the main buildings in the Hadrian’s Villa complex, a designated UNESCO World Heritage Site located in Tivoli (Rome, Italy), dating to the first half of the II century A.D. The plaster layers (arriccio and intonachino) and overlying original Roman paintings that form the concave wall of the portico as well as some bedding mortars of the pyramidal stone elements (i.e. cubilia) of the circular masonry have been studied in particular. In addition, the acid volcanic rocks of the cubilia have been investigated, aiming to understand their state of alteration and geological origin. By mineralogical-petrographic microscopy (OM), diffractometry (XRPD), Raman spectroscopy, Point Load Tests (PLT), helium pycnometry, and particle size analysis, the composition and granulometric distribution of the aggregate, type and characteristics of the binder, and various physical-mechanical properties (density, porosity, water absorption, imbibition and saturation indices, mechanical resistance) of mortars and stones were defined. In addition, through digital image analysis of thin sections, the binder/aggregate ratio and some geometric characteristics of the aggregates (e.g. circularity) were determined. The research aims to improve the knowledge of the constructive technologies of the Maritime Theatre through the analysis of its materials.

Archeological mortars are often composed of highly inhomogeneous materials and detailed analysis in most cases can be quite difficult. In this work, a Laser-Induced Breakdown Spectroscopy (LIBS) equipment with microscopic-scale spatial resolution was used to image the distribution of elements on real archeological samples of mortars and construction material used in the foundations of the Smederevo Fortress (Republic of Serbia). A double-pulse Nd:YAG at the fundamental wavelength (λ = 1064 nm) and a CCD spectrometer coupled with a commercial microscope were used to generate the plasma and acquire the LIBS spectra. Thanks to the combined use of an unsupervised clustering algorithm and the calibration-free procedure, the results obtained show that it is possible to obtain a good discrimination between materials of different composition, allowing a quick classification for further mineral-petrographic investigations.