139 research outputs found
SHELL (BIVALVIA, PTERIOMORPHIA)
No full textBiominerals are organo-minerals structures produced by living systems. Since the Cambrian, they contribute to the adaptation of living organisms to different environments by fulfilling a variety of functions that go along with adapted morphologies. One of the aims of biomineralization is to understand how organisms "sculpt" these complex morphologies at nano and molecular scales: we know that occluded organic matrix (OM) proteins influence the lattice parameters of biominerals [1] and that many of them strongly interact with the mineral phase in in vitro assays, but their exact roles are still to be known. The aim of my PhD is to understand the complex relationships between the organic and mineral phases. In the present study, I discuss the case of the Mediterranean fan mussel Pinna nobilis.
Like most molluscs, Pinna nobilis, the fan mussel, envelops its soft body with a highly ordered shell composed of two mineralized layers: the internal one is nacreous made of aragonite, while the outer one is made of long calcitic prisms that grow perpendicularly to the surface of the shell. This latter shell layer comprises an assemblage of insoluble periprismatic matrix (proteins + saccharides) and very acidic "intracrystalline" proteins and sugars, together with pigments. This shell layer was submitted to:
Morphological and spectral characterization: To unveil the complex and hierarchical structures of biomineral models, we have acquired high-resolution 2D and 3D images by using different microscopic and spectro-microscopic techniques at Synchrotron SOLEIL. Under UV light, we have recently evidenced a striking luminescent pattern - never observed before - in relation to pigments.
Biochemical analysis of organic matrix: we have analyzed the intra and inter-prismatic OM by gel electrophoresis, ELISA test and western blot. Moreover, a transcriptome constructed from the mantle tissues has helped us to identify by proteomics a large set of proteins associated to the formation of prisms.
The significance of our results is discussed here. Our data tend to show that the formation of "simple prisms" is an extremely regulated process, which requires several molecular actors
Les noirs de Pierre Soulages
No full textArticle co-rédigé par Pauline Hélou-de La Grandière, conservateur-restaurateur de peinture et doctorante (Héritages/INP/EUR Humanités, Création et Patrimoine) Pauline Hélou-de La Grandière, Mathieu Thoury et Lionel Simonot "Les noirs de Pierre Soulages", Technè, n° 55, "Matières noires, sens et substances, 1", 2023, p. 36-49 Commander le numéro Texte intégral disponible en novembre 2024 Introduction de l'article Bien que de nombreux travaux et ouvrages aient été consacrés à l’œ..
Microspectroscopic Investigation of Metal Soaps in Oil Paintings--a Case Study on late 19th Century Cobalt Green ((CoxZn1-xO) Paint
No full textMicrospectroscopic Investigation of Metal Soaps in Oil Paintings--a Case Study on late 19th Century Cobalt Green ((CoxZn1-xO) Pain
Identification non-destructive des vernis des oeuvres d'art par fluorescence UV
No full textFor centuries, varnishes applied on works of art have been prepared with natural resins. These natural products degrade in the course of time and consequently modify the visual aspect of the work of arts. Thus, restorers must reduce the layer of varnish using solvents chosen according to the nature of varnish and not deteriorating the pictorial layer. The identification of varnishes is thus essential for the choice of the apt solvent. Until now, that identification was obtained by chemical analyses using samples. With UV fluorescence, we developed a technique allowing nondestructive identification of varnishes which can be carried out in-situ and giving results in real time. This method is based on the comparison of the spectrum of fluorescence of an unknown varnish with those of a database of recent, artificially and naturally aged varnishes of reference. Examples of identification of varnishes on several works of art are presented in this work. In parallel, the first step toward the separation and the identification of principal the fluorophores contained within the resins were carried out by liquid chromatography coupled with the electrospray mass spectrometry.Depuis des siècles, les vernis apposés sur des œuvres anciennes sont constitués de résines naturelles. Ceux-ci se dégradent au cours du temps et modifient l'aspect visuel de l'œuvre. Les restaurateurs doivent donc alléger la couche de vernis à l'aide de solvants choisis selon la nature du vernis et n'altérant pas la couche picturale. L'identification des vernis est donc essentielle pour le choix solvant. Elle était, jusqu'ici obtenue par des analyses chimiques faites à partir de prélèvements. A l'aide de la fluorescence UV, nous avons développé une technique d'identification non-destructive des vernis, réalisable in-situ et donnant des résultats en temps réel. Cette méthode s'appuie sur la comparaison du spectre de fluorescence d'un vernis inconnu avec ceux d'une base de données de vernis de référence récents, vieillis artificiellement ou naturellement. Des exemples de reconnaissance des vernis sur plusieurs œuvres d'art du patrimoine sont présentés. Parallèlement, la séparation et l'identification des principaux fluorophores contenus au sein des résines ont été réalisées par chromatographie liquide couplée à la spectrométrie de masse utilisant l'ionisation par électrospray
NIRMA Nano-imagerie Infrarouge pour les Matériaux Anciens
No full textPrésentation donnée au cours de l'atelier DOPAMINE (Les données en sciences du patrimoine DIM Matriaux anciens et patrimoniaux) au cour duquel . Laurent Romary, chercheur invité dans le cadre du DIM Matériaux anciens et patrimoniaux, a rencontré les porteurs de projet d'équipements soutenus par le DIM, mais également tous les scientifiques intéressés à déposer un projet d'équipement auprès du DIM. Cet Atelier a pris la suite de l'Atelier du 7 février, à destination prioritairement des jeunes scientifiques
Synchrotron DUV luminescence micro-imaging to identify and map historical organic coatings on wood
No full textInternational audienceDeep ultraviolet (DUV) photoluminescence (PL) microimaging is an emerging approach to characterise materials from historical artefacts (see M. Thoury, J.-P. Echard, M. Réfrégiers, B. H. Berrie, A. Nevin, F. Jamme and L. Bertrand, Anal. Chem., 2011, 83, 1737–1745). Here we further assess the potential of the method to access a deeper understanding of multi-layered varnishes coating wooden violins and lutes. Cross-section micro samples from important 16th- to 18th-century instruments were investigated using synchrotron PL microimaging and microspectroscopy. Excitation was performed in the DUV and the near ultraviolet (NUV) regions, and emission recorded from the DUV to the visible region, at a submicrometric spatial resolution. Intercomparison of microspectroscopy and microimaging was made possible by radiometrically correcting PL spectra both in excitation and emission. Based on an optimised selection of emission and excitation bands, the specific PL features of the organic binding materials allowed a vastly enhanced discrimination between collagen-based sizing layers and oil/resin-based layers compared to epiluminescence microscopy. PL therefore appears to be a very promising analytical tool to provide new insights into the diversity of surface coating techniques used by instrument-makers. More generally, our results demonstrate the potential of synchrotron PL for studying complex heterogeneous materials beyond the core application of the technique to life sciences
Identification non-destructive des vernis des oeuvres d'art par fluorescence UV
No full textPARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF
DILUVIAN : Deciphering hidden Information with LUminescence of Vetigrastropoda using new Imaging ANalytical methods
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A New Synchrotron Approach to Study Ancient Materials: UV/Visible Photoluminescence Micro-Imaging
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Caractérisation physico-chimique avancée des collections des sciences de la terre à IPANEMA
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