88 research outputs found
Initiatives europĂ©ennes dâIPANEMA et du synchrotron SOLEIL pour lâĂ©tude des matĂ©riaux anciens
Les particularitĂ©s du rayonnement synchrotron, notamment sa trĂšs grande brillance et son spectre blanc des rayons X Ă lâinfrarouge lointain, en font une source de plus en plus employĂ©e pour lâĂ©tude de la composition chimique, des propriĂ©tĂ©s et de la rĂ©activitĂ© des matĂ©riaux patrimoniaux. La construction de lâInstitut photonique dâanalyse non destructive europĂ©en des matĂ©riaux anciens, attenant au synchrotron SOLEIL, par lâĂtat français et la RĂ©gion Ăle-de-France permet un soutien fortement accru des Ă©quipes françaises et internationales travaillant Ă lâĂ©tude des matĂ©riaux anciens. Les allers-retours entre dĂ©veloppement de mĂ©thodes et applications encouragent Ă la fois lâapparition de nouveaux instruments et un usage optimisĂ© de techniques de spectroscopie et dâimagerie de pointe. Le dĂ©veloppement dâIPANEMA sur le territoire de Paris-Saclay sâinscrit dans le cadre plus global de la mise en place de lâinfrastructure europĂ©enne E-RIHS, dĂ©diĂ©e Ă lâĂ©tude du patrimoine culturel et naturel.The specific features of synchrotron radiation, namely its very high brightness and its white spectrum from X-rays to far infrared light, make it an increasingly used source in the study of the chemical composition, properties and reactivity of ancient materials. Constructed by the French government and the Ăle-de-France region, adjacent to the SOLEIL synchrotron, IPANEMA (Institut photonique dâanalyse non-destructive europĂ©en des matĂ©riaux anciens/European Institute of Non-Destructive Photonic Analysis of Ancient Materials), provides extensive additional support to French and international teams involved in research into ancient materials. Interaction between the development of methods and applications encourage both the emergence of new instruments and an optimized use of spectroscopic techniques and cutting-edge imaging. The building of IPANEMA on the Paris-Saclay site is part of a more global strategy within E-RIHS, the European Research Infrastructure for Heritage Science
Xâray fluorescence spectroscopy of picrolite raw material on Cyprus
Picrolite artefacts comprise some of the most distinctive material remains in the prehistory of the island of Cyprus, in the Eastern Mediterranean. Picrolite exploitation dates from at least 12,000 years ago for the manufacture of personal ornaments and items with a symbolic function. It is commonly assumed that picrolite nodules were collected in secondary deposits on an ad hoc basis. This narrative, however, ignores the fact that picrolite carriers can only be found in very specific locations on the island, discrete from each other. Here we report initial outcomes of the application of handheld portable X-ray fluorescence (HHpXRF) and synchrotron-based X-ray fluorescence spectroscopy (SR-ÎŒXRF) to the analysis of picrolite raw materials performed at the newly opened PUMA beamline of the SOLEIL Synchrotron Radiation Facility. Our work refines the basic characteristics of the elemental constituents of the picrolite raw material and highlights key micro-structural differences between two distinct source regions on the Troodos Massif in western Cyprus. Picrolite source characterisation is expected to contribute significant new knowledge to the study of rare raw material consumption, prehistoric social organisation, networking and possible long-distance exchange of this idiosyncratic raw material within and beyond the islandâs geographic boundaries
Fur glowing under ultraviolet: in situ analysis of porphyrin accumulation in the skin appendages of mammals
Examples of photoluminescence (PL) are being reported with increasing frequency in a wide range of organisms from diverse ecosystems. However, the chemical basis of this PL remains poorly defined, and our understanding of its potential ecological function is still superficial. Among mammals, recent analyses have identified free-base porphyrins as the compounds responsible for the reddish ultraviolet-induced photoluminescence (UV-PL) observed in the pelage of springhares and hedgehogs. However, the localization of the pigments within the hair largely remains to be determined. Here, we use photoluminescence multispectral imaging emission and excitation spectroscopy to detect, map, and characterize porphyrinic compounds in skin appendages in situ. We also document new cases of mammalian UV-PL caused by free-base porphyrins in distantly related species. Spatial distribution of the UV-PL is strongly suggestive of an endogenous origin of the porphyrinic compounds. We argue that reddish UV-PL is predominantly observed in crepuscular and nocturnal mammals because porphyrins are photodegradable. Consequently, this phenomenon may not have a specific function in intra- or interspecific communication but rather represents a byproduct of potentially widespread physiological processes.publishedVersio
A new 3D positioner for the analytical mapping of non-flat objects under accelerator beams
We report the development of a 3D positioner for the elemental mapping of non-flat surfaces of heritage targets and its implementation in the external beam of the AGLAE accelerator, a joint research activity of the IPERION-CH European program.The positioner operates in two steps: 1) object surface is digitized using a 3D scanner implemented in the beamline. Surface points are interpolated onto a rectangular grid suitable for beam scanning. 2) Object is scanned under the beam using X/Y/Z stages holding a hexapod robot for rotations. During scanning, target surface is positioned with the Z stage and oriented perpendicular to the beam using hexapod rotations. Areas up to 100 à 100 mm 2 with a resolution of 50 ” m and 30° curvature of can be mapped on objects of 200 mm and 5 kg max. System operation was tested by recording PIXE maps on the polychrome decoration of a curved porcelain pot
A new Early Triassic crinoid from Nevada questions the origin and palaeobiogeographical history of dadocrinids
Knowledge of the early evolution of post-Palaeozoic crinoids mainly relies on the well-preserved and abundant material
sampled in Triassic Konservat-LagerstÀtten such as those from the Anisian Muschelkalk (Middle Triassic) of the
Germanic Basin. These crinoid-bearing LagerstÀtten have been central to understanding the rapid evolution and diversification
of crinoids after the dramatic Permian/Triassic Boundary biological crisis that led the class to near-extinction.
The Encrinida are the emblematic crinoids of the Triassic. They are mainly known from rich fossil deposits where their
abundant ossicles are at the origin of the extensive crinoidal limestone beds of the German Upper Muschelkalk. So far,
they were first represented in the Middle Triassic by the family Dadocrinidae and genus Dadocrinus. In the present work,
a new species Dadocrinus montellonis sp. nov., is described based on a well-preserved, almost complete articulated specimen
from the Spathian (Lower Triassic) of Nevada (USA). The new species differs from other species of Dadocrinus by
its palaeobiogeographic position but also by its earlier stratigraphic occurrence and ancestral morphology. It represents
the first reported occurrence of Dadocrinus outside the Germanic Basin prior to the Middle Triassic and also the oldest
firm evidence of its presence in the Early Triassic (middleâlate Spathian). This discovery sheds new light on the origin
of post-Palaeozoic crinoids. It suggests a much wider distribution than commonly assumed for the genus Dadocrinus
and implies that the first dadocrinids originated either in the Panthalassa or Tethys oceans, and then dispersed over long
distances in a relative short period of time
New thylacocephalans from the Early Triassic Paris Biota (Bear Lake County, Idaho, USA).
International audienceTwo new genera and species of thylacocephalans (Arthropoda, Thylacocephala), Parisicaris triassica Charbonnier and Ligulacaris parisiana Charbonnier, are described from the early Spathian Paris Biota. These new occurrences are the first reports of thylacocephalans from Triassic rocks in North America. They considerably enlarge the spatiotemporal distribution of these enigmatic arthropods and highlight their relatively high generic richness during the Early Triassic. It also confirms that the Triassic was the taxonomically richest period for Thylacocephala
Identification non-destructive des vernis des oeuvres d'art par fluorescence UV
For 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 siĂšcles, les vernis apposĂ©s sur des Ćuvres anciennes sont constituĂ©s de rĂ©sines naturelles. Ceux-ci se dĂ©gradent au cours du temps et modifient l'aspect visuel de l'Ćuvre. Les restaurateurs doivent donc allĂ©ger la couche de vernis Ă l'aide de solvants choisis selon la nature du vernis et n'altĂ©rant pas la couche picturale. L'identification des vernis est donc essentielle pour le choix solvant. Elle Ă©tait, jusqu'ici obtenue par des analyses chimiques faites Ă partir de prĂ©lĂšvements. A l'aide de la fluorescence UV, nous avons dĂ©veloppĂ© une technique d'identification non-destructive des vernis, rĂ©alisable in-situ et donnant des rĂ©sultats en temps rĂ©el. Cette mĂ©thode s'appuie sur la comparaison du spectre de fluorescence d'un vernis inconnu avec ceux d'une base de donnĂ©es de vernis de rĂ©fĂ©rence rĂ©cents, vieillis artificiellement ou naturellement. Des exemples de reconnaissance des vernis sur plusieurs Ćuvres d'art du patrimoine sont prĂ©sentĂ©s. ParallĂšlement, la sĂ©paration et l'identification des principaux fluorophores contenus au sein des rĂ©sines ont Ă©tĂ© rĂ©alisĂ©es par chromatographie liquide couplĂ©e Ă la spectromĂ©trie de masse utilisant l'ionisation par Ă©lectrospray
NIRMA Nano-imagerie Infrarouge pour les Matériaux Anciens
Présentation 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 auprÚs du DIM. Cet Atelier a pris la suite de l'Atelier du 7 février, à destination prioritairement des jeunes scientifiques
Identification non-destructive des vernis des oeuvres d'art par fluorescence UV
PARIS-BIUSJ-ThĂšses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF
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