21 research outputs found
Rilievo e rappresentazione 3D di un sito archeologico nell’ambito del progetto Urban a Trieste
No full textLa Soprintendenza per i Beni Ambientali, Architettonici,
Archeologici, Artistici e Storici della Regione Friuli Venezia Giulia sta gestendo dal 2000, nell’ambito del Programma di Iniziativa
Comunitaria Urban -Progetto Tergeste, diversi scavi, il cui obiettivo generale è quello di acquisire, elaborare ed archiviare i dati relativi al patrimonio storico-archeologico della Città Vecchia di Trieste, al fine di predisporre gli strumenti per la tutela e la valorizzazione di tale patrimonio. Il Dipartimento di Ingegneria Civile dell’Università di Trieste è già stato coinvolto nel 2000 dalla Soprintendenza per un primo rilievo fotogrammetrico di due colonne romane del I sec. a.C.
Nel 2007, assieme al gruppo di Trieste, è stato coinvolto anche il
Laboratorio A.S.T.R.O. della Sede di Topografia e Fotogrammetria del Dipartimento di Ingegneria Civile dell’Università di Pisa, per la
realizzazione di un rilievo dell’area, che nel frattempo ha subito
ulteriori scavi e rinvenimenti, tramite laser a scansione terrestre. Nel presente lavoro vengono descritte le diverse fasi del lavoro di rilievo ed analizzate le diverse modalità con cui è possibile dare una rappresentazione al rilievo stesso. Questa differenziazione dei
prodotti tiene conto soprattutto delle diverse esigenze dei soggetti
che poi devono operare decisioni ed interventi sul bene rilevato. Se il formato digitale per la visualizzazione e la navigazione
tridimensionale risulta idoneo in alcune applicazioni, per altre risulta insoddisfacente e la classica rappresentazione cartacea in forma di tavole a grande scala resta la rappresentazione di maggior praticità. In questi casi, quindi, il rilievo laser è un mezzo per la realizzazione delle immagini ortorettificate, ma la rappresentazione rimane quella tradizionale
Tempera and Tempera Grassa─From Wet Paints to Solid Films
No full textOld Masters frequently used paints containing both egg and oil binders to create their paintings. These two binders can be combined in the paint in many different ways resulting in substantially different behaviors of the wet paint but also affecting drying and curing reactions. This paper focuses on paints bound with egg (tempera paints), and the influence of added oil on microstructure, rheology, drying kinetics, and chemistry is discussed. Such egg tempera paints with oil are called fatty tempera, or tempera grassa (TG), and are sometimes believed to play an intermediate role between oil and tempera paints. Despite their hydrophobic nature, pigments do not enter into the oil droplets emulsified in a TG due to the adsorption of egg proteins on the pigment surface. We further show that the flow behavior of both paint types can be described using classical suspension rheology concepts. When combining the pigment, the egg yolk, and the oil into the calculation of the disperse phase volume fraction φ, minor differences in viscosity and onset of percolating network formation are attributed to the broader particle size distribution for TG. The dry-to-touch is controlled by the evaporation of water in both cases and reached within minutes. The added oil does not change the painting behavior in general; however, different brushability is observed on absorbent substrates when water is lost quickly and the remaining oil in TG keeps the paint soft. After the dry-to-touch state is reached, the oil cross-linking sets in, leading to a second hardening step. Egg components exert an antioxidant effect of the oil, which does affect not only the kinetics of the curing process but also its chemistry and is dependent on the microstructure of the paint film
Disclosing the chemistry of oil curing by mass spectrometry using methyl linoleate as a model binder
No full textThe structure of the polymeric fraction in an oil painting is believed to be strongly
connected to the stability of the paint layers over time, but its molecular
the characterisation is extremely difficult given the complex composition of a vegetable oil-based
polymer.
In this study, we report the implementation of a methodological approach for the
systematic mass spectrometric investigation of the molecular features of the products
of oxidative degradation and cross-linking of oil paint layers upon curing. The
approach is based on the use of methyl linoleate as a simplified model of an oil paint
binder. Gas-chromatography coupled with mass spectrometry, solid phase
microextraction gas chromatography-mass spectrometry, flow injection electrospray
mass spectrometry and evolved gas analysis mass spectrometry, are used to analyse
the evolution of compounds produced over seven months of natural ageing, from the
volatile products to the macromolecular and cross-linked fractions. The aim is to
improve our fundamental molecular understanding of the curing process of oil paints,
and to investigate the balance between oxidative degradation and cross-linking when
specific binder-pigment combinations are in place.
Model paint layers were prepared using lead white and ultramarine blue as pigments.
These two pigments are known to produce paint layers with different stability over time.
The use of methyl linoleate as a model oil binder greatly simplifies the mass spectral
features of the lipid paint fraction, enabling the detection of products of oxidation and
cross-linking with a new high level of molecular detail. Data clearly show that that
crucial differences between paints containing the two pigments establish with time,
which are mostly related to the cross-linked fraction
An Interdisciplinary Approach Towards the Integrated Safety-Security Assessment of Process Facilities Operating in the Maghreb Context
No full textExternal acts of interference towards industrial facilities have become a matter of increasing concern in recent years, especially in areas such as North Africa, where severe attacks to process facilities demonstrated the critical interface among integrated safety & security (ISS) aspects. The present work addressed this ISS concern and aimed at developing an interdisciplinary approach to support technical studies dedicated to the process industry. The first step consisted of a qualitative content analysis supporting the identification of critical ISS scenarios associated with process installations, as well as the critical socio-economic factors contributing to the terrorist threat. Next, the results of the qualitative analysis were implemented in a semi-quantitative methodology for the assessment of site attractiveness, with the aim of estimating the attack likelihood. Finally, the quantitative security risk assessment was carried out adopting: i) the attack likelihood estimated in the previous phase, and ii) a rigorous approach for the simulation of the dynamic evolution of ISS scenarios and related impact. For this purpose, the process simulator Honeywell UniSim® Design was used. The so evaluated accident impact and likelihood were combined using a risk matrix. The application to an industrial case study located in the Maghreb context was carried out in order to show the potentialities of the method and possible impact on the ISS enhancement of process industry
La Magistratura italiana. Formazione professionale e valutazioni di professionalita
No full textL’esercizio della giurisdizione presuppone un livello adeguato di professionalità dei magistrati che la esercitano e, insieme ad una buona formazione degli stessi, contribuisce al perfezionamento del livello di professionalità dell’intero Ordine giudiziario
Unravelling the chemistry of cadmium red oil paints by mass spectrometry and thermoanalytical techniques using methyl esters as model binders.
No full textThe target of the thesis is to unravel how cadmium red influences the curing of an oil paint. Oil paint is a form of a slow-drying paint that consists of particles of pigment suspended in a vegetable drying oil that forms a solid elastic film upon exposure to air. Linseed oil is one of the most common oils used since the antiquity and generates stable and resistant films, but the main drawback of this oil is that this films tent to yellow with ageing. Because of this, with the advent of the Industrial Revolution, the artists started to use new types of oils, such as safflower oil, which is a semi-drying oil. At the molecular level, methyl esters are simpler than triglycerides and for this reason the mass spectral features of compounds produced upon its curing are significantly simplified. To achieved the target, mass spectrometry and thermoanalytical techniques have been used. Cadmium red is a mineral inorganic pigment and is a solid solution of sulfur and selenium
The Chemistry of Mixed Media Paints
No full textThe 15th century in Italy marked a crucial moment in art history as Italian painters began exploring the integration of oil painting techniques, which had originated in Flanders, with traditional egg tempera methods. This blending of different media led to the creation of artworks where both oils and proteins coexisted, sometimes in separate layers, but also within the same layer of paint. However, the exact details of this transition remain unclear to this day, and little is known about the specific techniques and formulations that artists used or why they chose one over the other.
This PhD thesis centers on the study of two distinct mixed media painting techniques: tempera grassa (tg) and protein-coated pigment (pcp). Tempera grassa is essentially an emulsion where oil and pigment particles are suspended in water, with proteins present as a colloidal dispersion in the aqueous phase. In contrast, protein-coated pigment involves a layer of protein surrounding pigment particles, which are then dispersed in oil. These two techniques result in different microstructures, as they vary in how the pigment particles, proteins, and oils interact within the paint layer.
My project could not therefore be based on a systematic and statistically significant study of ancient samples. Instead, I decided to focus on model paints. Since the beginning of the project, a challenging question arose: how to prepare model paints and paint layers? For this reason, the thesis is structured around two main research pathways that have run in parallel throughout the three years of the PhD, with the first being functional to the second: 1) understanding which parameters must be controlled when
preparing model paints and 2) studying mixed media paints.
The thesis comprises five chapters. Chapter 1 presents a literature-based summary on the oxidation of lipids, the oxidation of proteins, and their cooxidation when simultaneously present. Chapter 2 of the thesis addresses the preparation of model paints, stressing the importance of controlling various parameters to achieve reproducible results. The research found that factors such as paint thickness, pigment storage conditions, type of pigment, oil type, and oil pre-treatment all significantly influenced the curing of ultramarine blue paints. One key discovery was that natural lapis lazuli, behaved differently from synthetic ultramarine blue. This was especially evident in its rheological and chemical properties, suggesting that the handling and treatment of pigments were essential to the formulation of effective oil paints. The study raises the question of whether Old Masters employed specific methods, such as coating pigments with proteins, to overcome the challenges posed by natural pigments like lapis lazuli.
Chapter 3 presents findings from advanced imaging techniques, such as confocal microscopy and synchrotron-based deep UV photoluminescence microimaging, to analyze the microstructures of tg and pcp paints. These methods revealed that in pcp, proteins seem to protect lipids from direct interaction with pigments, while in tg, the microstructure is more heterogeneous with several interfaces at play. Deep UV photoluminescence microimaging in particular appears potentially very useful for examining cross-sections of aged paint layers, potentially allowing scientists to study works of Old Masters. Chapter 4 expands on the chemical properties of tg and pcp paints using a multi-analytical approach. The results showed that lipid oxidation was the initial stage of the process, but proteins quickly became involved, leading to strong chemical interactions between the two. In pcp paints, the protein coating helped form a cross-linked polymer network, which reduced the degradation of lipids. Conversely, tg paints displayed a higher degree of oxidative damage due to their more complex and heterogeneous microstructure. In Chapter 5, proteomics methods, including electrophoresis and mass spectrometry, were applied to study the protein content in mixed media paints. The findings revealed that proteins in paints undergo cross-linking and oxidation, starting as soon as the paint is applied, with oxidation levels reaching those of aged tempera paint within just a month of formulation.
While tempera grassa remains a somewhat mysterious technique, it is often referenced in the context of mixed media painting but, there is no clear evidence that Old Masters employed this technique. Research has suggested that tempera grassa allows for slightly better color transitions compared to traditional tempera and maintains a softer consistency due to the oil's delayed drying. However, the implications of this slower drying process and the extent of oxidation in tempera grassa are not yet fully understood. Moreover, using egg yolk versus egg white in the formulation can influence the paint’s consistency, with egg yolk yielding a thicker paint with better hiding power.
On the other hand, protein-coated pigment (pcp) appears to offer several advantages. Coating pigments with egg white or egg yolk prevents issues with humidity and reduces the stiffening of the paint, which can sometimes occur with pure oil paints, due to unwanted absorption of humidity from the environment on the pigment particles. Additionally, pcp paints exhibit high yield stress, allowing for thick brushstrokes that maintain texture and have less yellowing over time compared to traditional oil paints. The slower drying time associated with egg white-based pcp could be problematic for certain techniques like layering, but it could be beneficial for wet-in-wet or alla prima methods, which require the paint to remain workable for longer. All in all, pcp appears as a promising technique that was likely used by the Old Masters, offering a practical means to modify paint properties, improve paint layer stability, and reduce yellowing over time
On the preparation of model ultramarine blue oil paint layers: factors affecting the wet paint flow and curing
No full textIn heritage science, preparing mock-ups is often a fundamental yet challenging aspect of experimental protocols. This work arises from the need to understand the critical factors that must be considered when preparing model oil paint layers. Specifically, the focus is on understanding the rheology and the curing process of oil paints, and the work was carried out selecting ultramarine blue as pigment and (semi)drying oils as binder. The factors investigated here are the types of pigment and oil, paint thickness, pigment storage conditions, and paint solids content. In this work, 10 different ultramarine blue pigments were selected, differing in terms of their origin (natural and synthetic), particle size distribution, presence of coating or additives, and overall composition. Cold pressed walnut, safflower and linseed oils were used, as well as linseed oils subjected to different pre-treatments, i.e., stand oil and alkali-refined oil. The rheological behavior of fresh model paints was investigated, focusing on the effect of parameters such as pigment particle size distribution and water content. Fresh model paints were also analyzed with ThermoGravimetric Analysis (TGA) under air flow at a constant temperature (80 °C), and some selected paints with microUV—Pyrolysis—Gas Chromatography—Mass Spectrometry (microUV-Py-GC-MS). This enabled us to compare the induction period of the curing reactions, as well as the balance between oxidative degradation and polymerization when the paint formulation was systematically varied. Results show how, in the case of ultramarine blue, the natural pigments behave differently from the synthetic ones, both from a rheological and from a chemical point of view. The study demonstrates that all the parameters investigated strongly affected both the rheology and the chemical curing of the oil paints, which must thus be taken into consideration when carrying out systematic studies
Thrombotic microangiopathy induced by interferon beta in patients with multiple sclerosis: three cases treated with eculizumab
No full text
