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Greener perspectives in Conservation Science : design, characterization, and evaluation of bioformulations for the cleaning of altered indoor metal heritage
Get PDFJury members:
Prof. Edith Joseph, thesis director, Université de Neuchâtel & Haute Ecole Arc, Switzerland
Prof. Stephan von Reuss, thesis co-director, Université de Neuchâtel, Switzerland
Prof. Giorgia Sciutto, thesis co-supervisor, Università di Bologna, Italy
Prof. Giuseppe Lazzara, Università di Palermo, Italy
Dr. David Thickett, English Heritage, United Kingdom
Defended on February 1, 2024
No de thèse : 3105L'avènement des principes de la "Chimie Verte" est désormais une force motrice inconditionnelle pour la recherche menée dans le domaine de la Science de la Conservation. L'attention portée aux risques potentiels liés aux méthodes de nettoyage conventionnellement employées dans la conservation des oeuvres d'art, qui reposent souvent sur l'utilisation de substances toxiques à base de pétrole, telles que les solvants et les agents complexants, est particulièrement importante. Dans ce contexte, la recherche doctorale présentée ici visait à explorer des alternatives plus écologiques pour le nettoyage des collections historiques en métal altérées.
Le problème central de la préservation des métaux réside dans le processus spontané et irréversible de corrosion vers lequel ils tendent naturellement. C'est pourquoi les conservateurs-restaurateurs (CRs) s'appuient normalement sur l'application de revêtements organiques pour protéger la surface métallique des agents atmosphériques (par exemple, l'eau, les espèces de sulfure gazeux). Toutefois, ces matériaux ont également tendance à se détériorer avec le temps sous l'effet de plusieurs facteurs environnementaux (température, lumière UV, etc.), ce qui entraîne une défaillance de ces systèmes de protection. Par conséquence, il est commun que l'apparence, la fonctionnalité ou les conditions de conservation des oeuvres d'art métalliques soient compromises par la présence de revêtements organiques altérés associés à des substrats métalliques sous-jacents corrodés, ce qui conduit à l'élimination nécessaire de ces deux caractéristiques de dégradation par les CRs.
Des solutions gélifiées vertes et innovantes ont donc été conçues pour traiter individuellement (action sélective) ou simultanément (double action contrôlée) la corrosion et les revêtements organiques altérés éventuellement présents sur les collections historiques en métal. Une grande attention a été accordée à la sélection des " composant-blocs " potentiellement renouvelables et biodégradables des gels. La recherche a conduit à une première étude de plusieurs bio-polymères, parmi lesquels le poly-3-hydroxybutyrate (PHB) a été sélectionné comme agent épaississant approprié pour concevoir des systèmes de nettoyage à double action. Deux organogels ont été développés à partir d'une matrice de poly-3-hydroxybutyrate, chargée de lactate d'éthyle et d'agents complexants pour l'élimination des revêtements organiques et de la corrosion, respectivement. Plus précisément, les potentialités des agents complexants biodégradables, tels que la déféroxamine B (DFO) et l'acide éthylènediamine-N,N′-disuccinique (EDDS), ont été explorées. Les cibles de nettoyage ont été sélectionnées comme étant les plus représentatives des alliages et revêtements organiques présents dans les collections historiques de métaux à l'intérieur. L'acier, le laiton et l'argent sterling ont donc été choisis comme substrats métalliques, tandis qu'une résine acrylique (Paraloid® B72) et une laque nitrocellulosique (Zaponlack) ont été les revêtements organiques étudiés.
Un protocole analytique multimodal a été réalisé sur les formulations gélifiées et les échantillons métalliques avant et après l'intervention de nettoyage afin d'évaluer l'efficacité et la fiabilité des méthodes de nettoyage. Globalement, les deux systèmes ont permis d'éliminer efficacement les matériaux organiques tout en assurant un nettoyage modéré de la corrosion. Ce résultat garantirait une intervention polyvalente, en ajustant le temps d'application des gels et la réitération, ce qui est une caractéristique recherchée pour le nettoyage contrôlé des collections historiques de métaux.
Dans une perspective audacieuse, les résultats obtenus ont été partagés avec les conservateurs-restaurateurs et la communauté scientifique afin de promouvoir l'exploitation des méthodes et matériaux innovants, tout en encourageant l'intérêt pour la recherche d'approches de production plus durables (par exemple, EDDS fabriqué sans utilisation de bromure d'éthylène) à l'échelle industrielle.
ABSTRACT
The advent of the Green Chemistry principles is nowadays an unconditional driving force for the research carried out in the field of Conservation Science. Great attention is currently addressed in response to the potential risks derived from cleaning methods conventionally employed in art conservation, which are frequently relying on the use of petroleum-based and toxic substances, such as solvents and complexing agents. Within this scenario, the doctoral research here discussed was addressed to explore greener alternatives for the cleaning of altered historical metal collections. The core issue for the preservation of metals lies in the spontaneous and irreversible process of corrosion towards which they naturally tend over time. Therefore, conservator-restorers (CRs) typically rely on the application of organic coatings to protect the metallic surface from atmospheric agents (e.g., water, gaseous sulphide species). However, also these materials tend to deteriorate through time due to several environmental factors (e.g., temperature, UV light), leading to a failure of these protective systems.
Consequently, it is common that the appearance, functionality, or conservation conditions of metal artworks are jeopardised by the presence of altered organic coatings associated to corroded underlying metal substrates, leading to the necessary removal of both these degradation features by CRs. Therefore, innovative greener gelled solutions were designed in order to tackle individually (i.e., selective action) or simultaneously (i.e., controlled double-action) corrosion and altered organic coatings possibly present on historical metal collections. Great attention was addressed to the selection of possibly renewable and bio-degradable gel “building-blocks”. The research led to a first investigation of several bio-polymers, among which poly-3-hydroxybutyrate (PHB) was selected as suitable thickening agent to design doubleaction cleaning systems. Namely, two organogels were developed using a poly-3-hydroxybutyrate matrix, loaded with ethyl lactate and complexing agents for the removal of organic coatings and corrosion, respectively. Specifically, the potential of biodegradable complexing agents, such as deferoxamine B (DFO)
and ethylenediamine-N,N′-disuccinic acid (EDDS), were explored. The cleaning targets were selected being the most representative of alloys and organic coatings present in indoor historical metal collections.
Therefore, steel, brass, and sterling silver were chosen as metal substrates, whereas an acrylic resin (i.e., Paraloid® B72) and a nitrocellulose lacquer (i.e., Zaponlack) were the organic coatings of interest. A multi-modal analytical protocol was performed on gelled formulations and metal samples before and after cleaning intervention in order to evaluate the efficiency and reliability of the innovative cleaning methods. In general terms, both cleaning systems provided an effective removal of the organic materials while yielding moderate cleaning on the corrosion layers. This outcome would ensure a versatile intervention, fine-tuning gel application time and reiteration, which is a sought feature for the controlled cleaning of historical metal collections.
From an audacious perspective, the results obtained within the doctoral research were shared with conservator-restorers and the scientific community aiming to promote the exploitation of the innovative methods and materials, while fostering the interest in researching for more sustainable approaches of production (e.g., EDDS manufactured without the use of ethylene bromide) at the industrial scale
The evolutionary origins of event cognition in hominids
No full textPhD thesis submitted to the Faculty of Science, Institute of Biology
Expert committee composition:
Thesis director – Prof. Klaus Zuberbühler, University of Neuchatel, Switzerland
Internal examiner – Prof. Adrian Bangerter, University of Neuchatel, Switzerland
External examiner – Prof. Michael Tomasello, University of Duke, United States
External examiner – Prof. Balthasar Bickel, University of Zurich, Switzerland
Defended on the 25th of September 2024How did syntax evolve in humans? Is there a direct transition from the simple forms observed in animal communication to the complex sentence structures seen in human languages? This thesis tested a new theory positing that human syntax is rooted in prelinguistic event cognition, an evolutionarily ancient propensity to decompose events into their causal components. Humans spontaneously attribute agents (doers of actions) and patients (undergoers) roles while viewing their interactions, i.e., “who does what to whom”, with a particular focus on agents. The current literature suggests that humans recognise agents faster than patients and dedicate more attention to them. Similarly in language, agents are typically placed before patients, are marked by simpler forms, and play a privileged role in language processing. But, how do animals understand the causal structure of events, how do they keep track of event roles, and in doing so, do they also experience a preference for the agent? This thesis aims to shed light on the evolution of event decomposition, as a putative precursor to human language and syntax, by comparing hominid species.
I first explored whether great apes, like humans, spontaneously encoded event roles. Using a switch cost paradigm (i.e., a reaction time experiment), I showed that switching the role (i.e., agent or patient) of the assigned target significantly increased the processing time of the participants. I then concluded that the propensity to spontaneously encode social events in terms of agents and patients is shared amongst hominids, and that it is impossible or very difficult to override this deeply anchored cognitive propensity. Secondly, I examined whether great apes also showed indications of agent preference. Using a non-linguistic task based on video clips that mimicked decision making during language processing, I found that all hominids had a robust preference for animate agents, especially when acting on objects. This preference transcended simple perceptual biases, again suggesting a shared propensity.
Building on these results I then tested for potential modulation of the agent preference by differences in cooperation levels. Results demonstrated that in both chimpanzees and humans, agent preference increased along the perceived cooperativity of the agent. Such results suggested that agent preference is affected by social factors, and similarly so in animals and humans. Finally, I focused on the computational abilities of hominids’ event perception. After watching video clips, participants selected the components of the events in serial order: the II agent, patient and action. Surprisingly, and in contrast to standard linguistic theory, all species, including humans, preferentially selected the action first, followed by the agent. The second preferred order was agent-action. I concluded that identifying the action was crucial for constructing the event structure, after which the agent preference became prominent.
Overall, these findings provide evidence that the ability to decompose events in terms of agent, patient and action evolved long before modern humans and, by extension, language. It implies that syntax-ready brains already existed for millions of years, dating back to at least the last common ancestor of hominids. What still remains unclear, however, is why the ability to externalise these structures with communication then evolved in humans and, correspondingly, why great apes, despite shared perceptual abilities, are prevented from sharing them with others
Computational exploration and analysis of meters and patterns in Arabic metrical poetry : detection, visualization, and clustering of structures and compositions
Get PDFCette thèse aborde le problème de l’insuffisance de données et d’outils de traitement automatique du langage naturel liés au système métrique de la poésie arabe, ce qui rend l’exploration des compositions poétiques difficile. Bien que le système métrique ait été largement étudié d’un point de vue linguistique, il a reçu beaucoup moins d’attention en linguistique computationnelle, où des données structurées et des techniques de traitement appropriées sont essentielles pour une analyse efficace. Pour aider à résoudre ce problème, la thèse propose des solutions dans trois domaines clés : les règles du système métrique arabe, les techniques de traitement automatique du langage naturel (NLP) et l’analyse et la visualisation des structures poétiques. Nous présentons Arabic Meters Identification System (AMIS) , un framework structuré organisé en modules spécialisés. Au coeur de AMIS, les données et les règles du système métrique arabe sont intégrées, caractérisant ainsi tous les mètres arabes. Des modules supplémentaires se concentrent sur la détection automatique des mètres dans les poèmes ou les vers individuels, avec une précision fiable de 99,97%. D’autres modules sont dédiés à l’analyse structurelle et à la visualisation des compositions poétiques, y compris des évaluations comparatives. En outre, cette thèse identifie les principales caractéristiques des structures poétiques arabes métrées grâce à une approche de Clustering basée sur cinq métriques : Evenness, Variability, Repetition, Pattern Potential et Pattern Usage. Nos résultats montrent que Repetition, Variability et Pattern Usage sont les métriques les plus significatives, avec seulement deux attributs suffisants pour caractériser la structure d’un poème. De plus, nous explorons le potentiel de la représentation visuelle de la structure de la poésie arabe, la rendant accessible aux locuteurs arabophones et non arabophones. Ces techniques de visualisation ont permis de découvrir de nouvelles métriques qui améliorent les résultats du Clustering, offrant des perspectives plus approfondies sur la structure de la poésie arabe.ABSTRACT:
This thesis addresses the issue of insufficiency of data and natural language processing (NLP) tools related to the metrical system of Arabic poetry, which makes the exploration of poetic compositions challenging. Although the metrical system has been extensively studied from a linguistic perspective, it has received far less attention in computational linguistics, where structured data and appropriate processing techniques are essential for effective analysis. To help address this problem, the thesis provides solutions across three key areas: Arabic metrical system rules, NLP techniques, and the analysis and visualization of poetic structures. We introduce Arabic Meters Identification System (AMIS), a structured framework organized into specialized modules. At its core, AMIS integrates the data and rules of the Arabic metrical system, which characterizes all Arabic meters. Additional modules focus on the automatic detection of meter in poems or individual verses, achieving a reliable accuracy of 99.97%. Other modules are dedicated to the structural analysis and visualization of poetic compositions, including comparative assessments. Furthermore, this thesis identifies the key features of metered Arabic poetic structures through a clustering approach based on five metrics: Evenness, Variability, Repetition, Pattern Potential, and Pattern Usage. Our findings show that Repetition, Variability, and Pattern Usage are the most significant metrics, with just two attributes being sufficient to characterize a poem’s structure. Additionally, we explore the potential of visual representation of Arabic poetry, making its structure visible and accessible to both Arabic and non-Arabic speakers. These visualization techniques uncovered new metrics that improve clustering outcomes, providing deeper insights into the structure of Arabic poetry
Mega-events and the minor
No full textMega-events like the Olympics and the football World Cups remain popular around the globe, regardless of their record of damaging host cities and societies. In parallel, research on mega-events continues to grow across a range of disciplines, including geography. Much of this literature remains fixed at global levels of analysis. In this light, mega-events suffer from a double problem: their planning and articulation too often cause harm to cities and societies and, simultaneously, research on mega-events focuses too much on the macro. This paper endeavours to address both problems by proposing to make sense of mega-events by thinking through the minor. This concern valorises micro scales and marginalised people, those who most often lose during mega-event hosting. The paper argues that geographers are uniquely positioned to conduct nuanced mega-event research across a globally diverse range of political-economic contexts, and calls for more geographers to contribute to this project in a move towards a critical geography of mega-events
Olympic limits: the sporting mega event comes to town
Get PDFThe Olympic city continues to grow beyond planetary boundarie
1974 – 2024 : Cinquante ans d’évolution de la politique criminelle en Suisse
No full textMélanges pour le 50ème anniversaire du GS
La protection contre les congés ne s’étend pas à la résiliation par le locataire
Get PDFRésumé et analyse, Tribunal fédéral – 4A_189/2022, destiné à la publication, Ire Cour de droit civil, Arrêt du 22 mai 202
Fermeture des entreprises pour lutter contre le COVID-19 : l’employeur était-il en demeure ? : commentaire de l’arrêt du Tribunal fédéral 4A_53/2023 du 30 août 2023
Get PDFRésumé et commentaire, Tribunal fédéral – 4A_53/2023 destiné à la publication, Ire Cour de droit civil, Arrêt du 30 août 2023 (d
Thematic engagements: Affects and learning in older age
Get PDFIn this paper, we propose a sociocultural perspective to consider affects in older age. The psychology of learning throughout the whole life course, including in the life of older adults, suggest that affects play an important role. However, developmental psychology has paid little attention to affects in learning and development, and even less to these aspects in older age. We believe that it is important to examine affects in older age because of their centrality in the lifecourse; but how to account for them? We propose the notion of thematic engagement to highlight the role of affects in older persons' learning and development, and to designate transversal and pluri-thematic interests across activities and domains of knowledge, which enable us to show that some topics, domains or interests become more important than others for a given person across time. We base our claims on a longitudinal study of older people engaging in different activities at home, in their neighbourhood, as well as in a daycare centre for older people, and provide three dialogical exemplars. We finally highlight some theoretical and empirical implications of our proposition
Mainlevée provisoire pour des loyers impayés et défauts de la chose louée : de l’angélisme à la preuve diabolique
No full textRésumé et analyse, Tribunal fédéral – 4A_645/2023, Ire Cour de droit civil, Arrêt du 25 janvier 202