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Résumé Si l’on en croit al-Iṣfahānī, c’est à la présence d’Abū Qaṭīfa parmi les auteurs des trois premières chansons choisies que le Kitāb al-Aġānī doit en partie sa structure si singulière : l’auteur des vers de la première chanson n’étant ni le plus grand ni le plus ancien des poètes, le livre ne pouvait adopter une progression thématique, ni chronologique, ni hiérarchique. Cet article fait l’hypothèse que le premier couple de notices biographiques (celles d’Abū Qaṭīfa et Maʿbad) du Kitāb al-Aġānī a valeur de pacte de lecture et porte un commentaire auctorial général sur l’ouvrage. Nous montrons l’importance de la réflexivité comme principe de composition et de lecture à partir de trois thèmes introduits par la première chanson : la nostalgie, le fait de se défendre soi-même de l’abaissement et du mépris, et la capacité à garder le secret. Ces thèmes reçoivent, dans les deux notices qui suivent, un écho tel qu’ils se laissent lire comme l’exergue de l’ouvrage.

This paper provides a review of the characterization of organic systems via X-ray Raman scattering (XRS) and a step-by-step guidance for its application. We present the fundamentals of XRS required to use the technique and discuss the main parameters of the experimental set-ups to optimize spectral and spatial resolution while maximizing signal-to-background ratio. We review applications that target the analysis of mixtures of organic compounds, the identification of minor spectral features, and the spatial discrimination in heterogeneous systems. We discuss the recent development of the direct tomography technique, which utilizes the XRS process as a contrast mechanism for assessing the three-dimensional spatially resolved carbon chemistry of complex organic materials. We conclude by exposing the current limitations and provide an outlook on how to overcome some of the existing challenges and advance future developments and applications of this powerful technique for complex organic systems.

International audience; Egyptian blue and green are among the oldest synthetic pigments produced by humanity. The two pigments are complex multi-phase copper-based systems synthesised with different protocols from the same raw materials. Since the 2000s, synchrotron X-ray techniques have provided significant new insights on their chemistry and microstructure. However, the potential impact of high flux irradiation of these pigments has not yet been studied despite the fact that it can lead to visual discoloration and less readily observable alterations such as defects formation or redox changes. In this work, we investigate the effects of synchrotron X-ray irradiation on Egyptian blue and green samples. Radiation-induced effects are monitored after irradiation at increasing doses using electron paramagnetic resonance (EPR) spectroscopy at temperatures of 290 K and 30 K. The cupric ion (Cu2+) is in D4h axial geometry in Egyptian blue and in disordered geometry in Egyptian green, which makes the two pigments very easily identifiable by EPR. Egyptian green samples are found to be much more sensitive to X-rays than Egyptian blue. In particular, a browning of the green samples is observed from the lowest doses tested while no color change is detected for the blue ones. Three types of radiation-induced defects are detected after irradiation: E′, non-bonding oxygen hole and aluminum hole centers. Correlations between defect intensity and dose are calculated. Archaeological and modern pigments (whether blue or green) do not show the same reactivity to X-rays, which opens the prospect of using radiation-induced defects as a marker of their history.

International audience; For thousands of years, the unique physicochemical properties of plant exudates have defined uses in material culture and practical applications. Native Australian plant exudates, including resins, kinos, and gums, have been used and continue to be used by Aboriginal Australians for numerous technical and cultural purposes. A historic collection of well-preserved native Australian plant exudates, assembled a century ago by plant naturalists, gives a rare window into the history and chemical composition of these materials. Here we report the full hierarchical characterization of four genera from this collection, Xanthorrhoea, Callitris, Eucalyptus, and Acacia, from the local elemental speciation, to functional groups and main molecular markers. We use high-resolution X-ray Raman spectroscopy (XRS) to achieve bulk-sensitive chemical speciation of these plant exudates, including insoluble, amorphous, and cross-linked fractions, without the limitation of invasive and/or surface specific methods. Combinatorial testing of the XRS data allows direct classification of these complex natural species as terpenoid, aromatic, phenolic, and polysaccharide materials. Differences in intragenera chemistry was evidenced by detailed interpretation of the XRS spectral features. We comple- ment XRS with Fourier-transform infrared (FT-IR) spectroscopy, gas chromatography– mass spectrometry (GC-MS), and pyrolysis–GC-MS (Py-GC-MS). This multimodal approach provides a fundamental understanding of the chemistry of these natural materials long used by Aboriginal Australian peoples.

Les textiles sont perissables dans la plupart des environnements archeologiques. L’un des principaux processus conduisant a la preservation exceptionnelle de leur morphologie resulte du contact avec un objet metallique, un phenomene connu sous le nom de « mineralisation ». Nous presentons ici l’etude d’un textile ancien en lin provenant du site de Nausharo (vallee de l’Indus, Balochistan, Pakistan) et date du IIIe millenaire av. J.-C. Cette etude est integree dans un programme de recherche sur des vestiges textiles mineralises au contact d’objets en cuivre corrodes particulierement anciens, mene avec le CNRS-UMR 7041/ ArScAn, le musee du Louvre et le musee du quai Branly-Jacques Chirac, et mettant a profit de nouvelles approches d’investigation. Il s’agit de la premiere attestation directe de la presence de lin tisse sur le site. L’imagerie tomographique 3D sur synchrotron permet d’acceder a des donnees quantitatives encore inaccessibles sur ces textiles, comme le nombre precis de fibres par fil. Nous avons par ailleurs, a partir d’approches complementaires, detecte la presence de signatures cellulosiques exceptionnellement bien conservees, meme dans le cas d’un tel textile extremement transforme par les mecanismes physico-chimiques d’alteration depuis son depot jusqu’a nos jours. La description de ces restes rares permet d’approfondir l’interpretation archeologique de ces textiles et nous informe egalement sur l’etat d’alteration du support metallique dont la corrosion a joue un role-cle dans la preservation des fibres.

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 × 100 mm2 with a resolution of 50 µm 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.

La présente réflexion questionne la transformation des espaces traditionnels en centres urbains modernes, sous la bannière de l’action humanitaire. En Afrique, l’attrait des villes occidentales, l’exubérance du phénomène migratoire (multifactoriel) et la forte croissance démographique entraînent une urbanisation rapide et incontrôlée. Au Tchad, les conflits et crises (internes et externes) ont un double rapport à l’urbanisation des villes traditionnelles et des villages. Si au premier abord les effets en termes de dégâts matériaux et de désastres humanitaires obèrent des dynamiques urbaines, ces conflits et crises constituent cependant un catalyseur des transformations rurales et urbaines à travers le déploiement de l’action humanitaire. Cette tendance, qui fait l’objet de ce travail, invite à questionner l’influence de l’action humanitaire sur l’urbanisation, en prenant le cas des villes d’Abéché et Goré au Tchad. Les analyses s’adossent sur la perspective sociologique balandienne centrée sur le concept de « mutations » qui appréhende ici l’action humanitaire comme un facteur de construction et d’identification d’un nouveau type de villes. Elles s’appuient également sur des données empiriques recueillies grâce aux observations directes et indirectes menées dans les zones d’étude (Abéché et Goré). Le premier axe de la réflexion procède à une sociographie de l’action humanitaire au Tchad afin de faire ressortir ses fondements et ses ressorts. Le second moment de l’analyse met l’emphase sur les éléments de complémentarité et de divergence entre l’action humanitaire et l’urbanisation. Le troisième moment enfin s’appesantit sur les défis liés à l’urbanisation par l’action humanitaire au Tchad.

La présente réflexion questionne la transformation des espaces traditionnels en centres urbains modernes, sous la bannière de l’action humanitaire. En Afrique, l’attrait des villes occidentales, l’exubérance du phénomène migratoire (multifactoriel) et la forte croissance démographique entraînent une urbanisation rapide et incontrôlée. Au Tchad, les conflits et crises (internes et externes) ont un double rapport à l’urbanisation des villes traditionnelles et des villages. Si au premier abord les effets en termes de dégâts matériaux et de désastres humanitaires obèrent des dynamiques urbaines, ces conflits et crises constituent cependant un catalyseur des transformations rurales et urbaines à travers le déploiement de l’action humanitaire. Cette tendance, qui fait l’objet de ce travail, invite à questionner l’influence de l’action humanitairesur l’urbanisation, en prenant le cas des villes d’Abéché et Goré au Tchad. Les analyses s’adossent sur la perspective sociologique balandienne centrée sur le concept de « mutations » qui appréhende ici l’action humanitaire comme un facteur de construction et d’identification d’un nouveau type de villes. Elles s’appuient également sur des données empiriques recueillies grâce aux observations directes et indirectes menées dans les zones d’étude (Abéché et Goré). Le premier axe de la réflexion procède à une sociographie de l’action humanitaire au Tchad afin de faire ressortir ses fondements et ses ressorts. Le second moment de l’analyse met l’emphase sur les éléments de complémentarité et de divergence entre l’action humanitaire et l’urbanisation. Le troisième moment enfin s’appesantit sur les défis liés à l’urbanisation par l’action humanitaire au Tchad.

This article aims to determine the specificity of the notion of taḫyīl in ʿAbd al-Qāhir al-Ǧurǧānī’s (d. 471/1078) work. We will attempt to define this rhetorical device and explain the rhetorician’s interest in it. Taḫyīl consists in taking a word or sentence used in a figurative sense, in its literal sense. Although this definition is well-known, it remains uncertain in many respects (what is its decisive criteria? Is it a figure?). To answer these questions, it is necessary to take into account the ethico-rhetorical frame of the question of the taḫyīl in al-Ǧurǧānī’s work. It is first determined as a rhetorical misuse resulting from a deceptive syllogism, and then as a specificity of poetry: indeed, taḫyīl is not to be blamed only in poetry. We will show that taḫyīl should not be considered as a figure but as a topos (literally a “place,” in Aristotelian rhetoric) used to overemphasize one’s statement, i.e. to provide an excess of the assertion (mubālaġa fī l-iṯbāt).

The use of noise, defined as an indeterminate complex of sound, initiated a radical shift of the field of “music.” Between Pierre Schaeffer and John Cage there is a common point : against the hierarchical principals that rule music, they both pose equality of all sound material. Examining the case of Pierre Schaeffer and musique concrète, this essay asks how noise, as a raw material, breaks the logic of mimesis. How does this material imply new ways of composing or listening, a new “partage du sensible”?

International audience; Myriapods were, together with arachnids, the earliest animals to occupy terrestrial ecosystems, by at least the Silurian. The origin of myriapods and their land colonization have long remained puzzling until euthycarcinoids, an extinct group of aquatic arthropods considered amphibious, were shown to be stem-group myriapods, extending the lineage to the Cambrian and evidencing a marine-to-terrestrial transition. Although possible respiratory structures comparable to the air-breathing tracheal system of myriapods are visible in several euthycarcinoids, little is known about the mechanism by which they respired. Here, we describe a new euthycarcinoid from Upper Devonian alluvio-lagoonal deposits of Belgium. Synchrotron-based elemental X-ray analyses were used to extract all available information from the only known specimen. Sulfur X-ray fluorescence (XRF) mapping and spectroscopy unveil sulfate evaporation stains, spread over the entire slab, suggestive of a very shallow-water to the terrestrial environment prior to burial consistent with an amphibious lifestyle. Trace metal XRF mapping reveals a pair of ventral spherical cavities or chambers on the second post-abdominal segment that do not compare to any known feature in aquatic arthropods, but might well play a part in air-breathing. Our data provide additional support for amphibious lifestyle in euthycarcinoids and show that different respiratory strategies were used during the marine-to-terrestrial transition in the myriapod lineage.

Precambrian cellular remains frequently have simple morphologies, micrometric dimensions and are poorly preserved, imposing severe analytical and interpretational challenges, especially for irrefutable attestations of biogenicity. The 1.88 Ga Gunflint biota is a Precambrian microfossil assemblage with different types and qualities of preservation across its numerous geological localities and provides important insights into the Proterozoic biosphere and taphonomic processes. Here we use synchrotron-based ptychographic X-ray computed tomography to investigate well-preserved carbonaceous microfossils from the Schreiber Beach locality as well as poorly-preserved, iron-replaced fossil filaments from the Mink Mountain locality, Gunflint Formation. 3D nanoscale imaging with contrast based on electron density allowed us to assess the morphology and carbonaceous composition of different specimens and identify the minerals associated with their preservation based on retrieved mass densities. In the Mink Mountain filaments, the identification of mature kerogen and maghemite rather than the ubiquitously described hematite indicates an influence from biogenic organics on the local maturation of iron oxides through diagenesis. This non-destructive 3D approach to microfossil composition at the nanoscale within their geological context represents a powerful approach to assess the taphonomy and biogenicity of challenging or poorly preserved traces of early microbial life, and may be applied effectively to extraterrestrial samples returned from upcoming space missions.

One of the greatest benefits of synchrotron radiation is the ability to perform chemical speciation analysis through X-ray absorption spectroscopies (XAS). XAS imaging of large sample areas can be performed with either full-field or raster-scanning modalities. A common practice to reduce acquisition time while decreasing dose and/or increasing spatial resolution is to compare X-ray fluorescence images collected at a few diagnostic energies. Several authors have used different multivariate data processing strategies to establish speciation maps. In this manuscript, the theoretical aspects and assumptions that are often made in the analysis of these datasets are focused on. A robust framework is developed to perform speciation mapping in large bulk samples at high spatial resolution by comparison with known references. Two fully operational software implementations are provided: a user-friendly implementation within the MicroAnalysis Toolkit software, and a dedicated script developed under the R environment. The procedure is exemplified through the study of a cross section of a typical fossil specimen. The algorithm provides accurate speciation and concentration mapping while decreasing the data collection time by typically two or three orders of magnitude compared with the collection of whole spectra at each pixel. Whereas acquisition of spectral datacubes on large areas leads to very high irradiation times and doses, which can considerably lengthen experiments and generate significant alteration of radiation-sensitive materials, this sparse excitation energy procedure brings the total irradiation dose greatly below radiation damage thresholds identified in previous studies. This approach is particularly adapted to the chemical study of heterogeneous radiation-sensitive samples encountered in environmental, material, and life sciences.

This article considers the concept of a ‘language of things’, which Pierre Schaeffer developed in his early work, the Essai sur la radio et le cinema (1941–42). On the basis of a careful consideration of this text, it will appear that the ‘language of things’ engages a specific posture that shows, in the process of concrete music’s emergence, two distinct but interrelated aspects: one concerning things themselves and the other concerning language. It is this knot, this interwovenness, that we will try to understand in this article. The article will show that the promotion of noise is directly linked to the deconstruction of language and that these two processes, which can be precisely identified in Schaeffer’s early works, refer to a fundamental switch, signalling the birth of musique concrète.

X-ray Raman multispectral imaging identifies the 3D chemistry of carbon in entire organic paleontological specimens., The in situ two-dimensional (2D) and 3D imaging of the chemical speciation of organic fossils is an unsolved problem in paleontology and cultural heritage. Here, we use x-ray Raman scattering (XRS)–based imaging at the carbon K-edge to form 2D and 3D images of the carbon chemistry in two exceptionally preserved specimens, a fossil plant dating back from the Carboniferous and an ancient insect entrapped in 53-million-year-old amber. The 2D XRS imaging of the plant fossil reveals a homogeneous chemical composition with micrometric “pockets” of preservation, likely inherited from its geological history. The 3D XRS imaging of the insect cuticle displays an exceptionally well preserved remaining chemical signature typical of polysaccharides such as chitin around a largely hollowed-out inclusion. Our results open up new perspectives for in situ chemical speciation imaging of fossilized organic materials, with the potential to enhance our understanding of organic specimens and their paleobiology.

South African rock art provides a window into the Bushman worldview. For a better understanding of Bushman history and beliefs and the conservation of rock art sites, a better knowledge of the materials making up the paints, the mineral accretions and their alterations is required. A conjunction of imaging techniques (optical microscopy, SEM–EDX, Raman spectromicroscopy and synchrotron FT–IR) allowed us to describe the complex layered fabric that evidences a history of accretion, painting and alteration in eight samples of painted rock. Two types of paints are identified and the distribution of calcium oxalates is discussed in terms of conservation and dating potential.

Rédigé dans la foulée de l’Année européenne du patrimoine culturel, ce numéro spécial de la revue Reflets de la Physique et du Bulletin de l’Union des professeurs de physique et de chimie présente des aspects complémentaires de la physique moderne des matériaux de l’archéologie, de l’histoire de l’art, de l’histoire naturelle et des sciences de la conservation.

International audience; Fish otoliths are biogeochemical archives of environmental conditions and are a valuable tool for examining life traits. These sclerochronological life history records, accessed through geochemical analyses, are widely used in fisheries sciences, and are seeing growing use as palaeoenvironmental archives or for reconstruction of past human activities. The fidelity of such reconstructions relies on the preservation of the biogenic geochemistry, which may be altered through diagenetic processes. In this work, a methodology is provided that enables measurement of elemental concentrations with a high precision with simultaneous quality control of the data to ensure high reliability and a multi-technique sample marking strategy to ensure precise alignment. Thin sections of four archaeological and two modern otoliths from the Pacific coast of South America were examined by synchrotron mu XRF. High-definition elemental maps of sample sections up to 3.2 x 1.0 mm(2) (V x H) were produced with an on-sample spot size of 6.0 x 16 mu m(2). Thirteen elementswere detected, some of which may be useful indicators of diagenetic alteration. Strontium was accurately quantified and one sample presented local concentrations above the previously described range in literature. The quantity of collected data allows the use of statistical approaches to examine the intra- and inter-sample Sr distribution. A highly reliable profile, produced by integrating multiple points, additionally permits identification of defects and potential alteration along its length through changes in median absolute deviation. Contamination at the edge of some of the specimens was evidenced from preparation and other post-mortem alterations, even in modern samples, however diagenetic alteration in the elemental signals was not evidenced significantly further than a few hundred micrometres deep in the samples. Medium-energy SR-mu XRF therefore provides a fast and sensitive elemental probe without a visible effect on the sample, and the integration volume which limits the attainable lateral resolution in this energy range is discussed. This paper discusses the methodological limitations and opens new perspectives in the analysis of biomineral carbonate palaeoproxies. (C) 2015 Elsevier B.V. All rights reserved.

International audience; Carbon compounds are ubiquitous and occur in a diversity of chemical forms in many systems including ancient and historic materials ranging from cultural heritage to paleontology. Determining their speciation cannot only provide unique information on their origin but may also elucidate degradation processes. Synchrotron-based X-ray absorption near-edge structure (XANES) spectroscopy at the carbon K-edge (280−350 eV) is a very powerful method to probe carbon speciation. However, the short penetration depth of soft X-rays imposes stringent constraints on sample type, preparation, and analytical environment. A hard X-ray probe such as X-ray Raman scattering (XRS) can overcome many of these difficulties. Here we report the use of XRS at ∼6 keV incident energy to collect carbon K-edge XANES data and probe the speciation of organic carbon in several specimens relevant to cultural heritage and natural history. This methodology enables the measurement to be done in a nondestructive way, in air, and provides information that is not compromised by surface contamination by ensuring that the dominant signal contribution is from the bulk of the probed material. Using the backscattering geometry at large photon momentum transfer maximizes the XRS signal at the given X-ray energy and enhances nondipole contributions compared to conventional XANES, thereby augmenting the speciation sensitivity. The capabilities and limitations of the technique are discussed. We show that despite its small cross section, for a range of systems the XRS method can provide satisfactory signals at realistic experimental conditions. XRS constitutes a powerful complement to FT-IR, Raman, and conventional XANES spectroscopy, overcoming some of the limitations of these techniques.

The synchrotron characterisation of archaeological and heritage materials has undergone a steep development in the past years, among a range of other advanced characterisation techniques. For synchrotron techniques alone, close to a hundred articles were published in 2011 on such materials, prompting new developments at large scale facilities. However, few publications have discussed the specific characteristics of heritage materials in their advanced spectroscopic and imaging study. Here, we suggest that a greater consideration be put on the specificities of ancient materials and their theoretical implications on the analytical process. In particular, we discuss the importance of the a posteriori framework of the study of heterogeneous materials considered in their historicity as structuring parameters of their study. Major implications are the relevance of trace analyses, those of majors and we suggest, more importantly, the dynamics between both endpoints. The on-going development of multimodal spectral imaging appears as a way to better address corresponding difficulties. Epistemologically, we suggest that a reflexive approach be developed to explain, structure and possibly contribute to narrowing down the field of possible methodological research.

The medieval iron market in Ariege (French Pyrenees) is characterised by its complexity leading to many questions regarding the ore used in relation to the artefacts encountered in archaeological settings. Despite the conclusive study of the treaty that regulated iron vs. coal exchanges from the 14th to the 19th c. by Verna et al., many questions remain unanswered concerning provenance and circulation of ores and products. Based on a combination of trace elemental analysis and multivariate statistical methods (discriminant analysis, hierarchical clustering analysis), we propose to follow an elemental-based signature from ore to artefacts, suited to the direct iron process, to clarify provenance hypotheses. We define the chemical signature of the Ariege area and compare it to that of slag inclusions in artefacts uncovered in several main archaeological sites from the Ariege area but also outside of this region. The results from this study are consistent with prior knowledge from historical sources. In the Ariege region, results highlight the multiple origins of products encountered at Montreal-de-Sos, a site close to known trade routes, whereas the isolated Castel-Minier site primarily contained objects from local ores and most objects retrieved from the Mirabat castle (Couserans) are coming from outside Ariege, possibly an indirect consequence from the exchange treaty. The presence of pins made of Ariegean ores is also demonstrated in the far more distant Capestang collegiate (near Narbonne, outside Ariege). This opens the way to finer studies in the politico-economical control of the iron supply for the building of medieval monuments in Southern France.

A l’occasion des vingt-cinq ans de la premiere publication relatant une experience synchrotron sur un objet ancien – conduite au Lure a Orsay – nous evoquons l’histoire de ces developpements depuis les premices jusqu’a l’essor actuel des modalites d’imagerie synchrotron. L’ouverture du laboratoire Ipanema au synchrotron Soleil facilitera l’utilisation et le developpement de methodes synchrotron dans la gamme des rayons X (imagerie de balayage de micro-echantillons et d’objets ; microtomographie de fossiles paleontologiques), de l’UV/visible et de l’infrarouge pour l’etude des materiaux anciens.

International audience

International audience; Deep 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.

Synchrotron radiation (SR) has become a preferred technique for the analysis of a wide range of archeological samples, artwork, and museum specimens. While SR is called a nondestructive technique, its effect on proteinaceous specimens has not been fully investigated at the molecular level. To investigate the molecular level effects of synchrotron X-ray on proteinaceous specimens, we propose a methodology where four variables are considered: (1) type of specimen: samples ranging from amino acids to proteinaceous objects such as silk, wool, parchment, and rabbit skin glue were irradiated; (2) synchrotron X-ray energy; (3) beam intensity; (4) irradiation time. Irradiated specimens were examined for both macroscopic and molecular effects. At macroscopic levels, color change, brittleness, and solubility enhancement were observed for several samples within 100 s of irradiation. At molecular levels, the method allowed one to quantify significant amino acid modifications. Aspartic acid (Asp), wool, parchment, and rabbit skin glue showed a significant increase in Asp racemization upon increasing irradiation time with rabbit skin glue showing the greatest increase in d-Asp formation. In contrast, Asp in silk, pure cystine (dimer of cysteine), and asparagine (Asn) did not show signs of racemization at the irradiation times studied; however, the latter two compounds showed significant signs of decomposition. Parchment and rabbit skin glue exhibited racemization of Asp, as well as racemization of isoleucine (Ile) and phenylalanine (Phe) after 100 s of irradiation with a focused beam. Under the experimental conditions and sample type and dimensions used here, more change was observed for focused and low energy (8 keV) beams than unfocused or higher energy (22 keV) beams. These results allow quantification of the change induced at the molecular level on proteinaceous specimens by synchrotron X-ray radiation and help to define accurate thresholds to minimize the probability of damage occurring to cultural heritage specimens. For most samples, damage was usually observed in the 1-10 s time scale, which is about an order of magnitude longer than SR studies of cultural heritage under X-ray fluorescence (XRF) mode; however, it is consistent with the duration of X-ray absorption spectroscopy (XAS) and microcomputed tomography (μCT) measurements.

Version francaise Le 21 avril 2005, a l'issue de la session consacree aux potentialites du rayonnement synchrotron en archeometrie s'est tenue une table ronde dont nous proposons ici de resumer les principales interventions. Cet echange visait a recenser les principales attentes des chercheurs des sciences humaines dans le contexte du demarrage prochain (fin 2006) du nouveau synchrotron francais, SOLEIL (Gif-sur-Yvette), et de la mise en place par le synchrotron d'une interface dediee aux uti...

International audience; In order to fully characterize the zinc white artists' pigment (ZnO), much used since the mid-nineteenth century, three samples collected in the early 20th century were studied using a combination of synchrotron and macroscopic photoluminescence spectroscopy and imaging. An improved microscope setup based on synchrotron microspectroscopy and microimaging was used to study the powders dispersed onto indium foil. The synchrotron setup offered a diffraction-limited resolution of 153 nm. The PL spectra of individual grains were measured and the distribution of particles' emission spectra was mapped at the nanoscale. The results revealed that while the samples have apparent homogeneous photoluminescence behavior at the macroscale (bulk), their PL signatures are inhomogeneous below 20 μm. At the nanoscale the three powder samples have quite different PL signatures. Different sources, perhaps even different batches, of zinc white might be readily differentiated using this method.

Loïc Bertrand, Philippe Dillmann and Ina Reiche introduce the Synchrotron radiation and neutrons in art and archaeology 2014 themed issue, and give an overview of the conference held in the Louvre Museum, Paris.

International audience; IPANEMA, a research platform devoted to ancient and historical materials (archaeology, cultural heritage, palaeontology and past environments), is currently being set up at the synchrotron facility SOLEIL (Saint-Aubin, France; SOLEIL opened to users in January 2008). The new platform is open to French, European and international users. The activities of the platform are centred on two main fields: increased support to synchrotron projects on ancient materials and methodological research. The IPANEMA team currently occupies temporary premises at SOLEIL, but the platform comprises construction of a new building that will comply with conservation and environmental standards and of a hard X-ray imaging beamline today in its conceptual design phase, named PUMA. Since 2008, the team has supported synchrotron works at SOLEIL and at European synchrotron facilities on a range of topics including pigment degradation in paintings, composition of musical instrument varnishes, and provenancing of medieval archaeological ferrous artefacts. Once the platform is fully operational, user support will primarily take place within medium-term research projects for 'hosted' scientists, PhDs and post-docs. IPANEMA methodological research is focused on advanced two-dimensional/three-dimensional imaging and spectroscopy and statistical image analysis, both optimized for ancient materials.

International audience

International audience; What is Stradivari's “secret”? The composition of the mythical varnish that coats Stradivari's violins has raised controversial assumptions for the past two centuries. By using a complementary array of analytical tools, the chemical microstratigraphy of these varnishes has been established. The results provide information on the materials and techniques that were used by the Master, with a detailed characterization of the varnish.

This chapter surveys the use of synchrotron radiation in archaeology, art history, conservation science, and palaentology. It follows on from the preceeding introduction on synchrotron radiation given in Chapter 1 (Professor Dudley Creagh). After giving a brief survey of the current use of synchrotron radiation the author describes both invasive and non-invasive techniques for the examination of artefacts and their environment. Examples are given in the field of conservation science through the study of the alteration of iron artefacts and waterlogged wood using micro-X-ray spatial fluorescence mapping, and in that of paleontology with the description of micro-tomographic studies of bones of a primate from the Late Eocene period are described. An introduction is given to the complementary techniques of synchrotron infrared Fourier Transform microspectroscopy, micro-X-ray absorption near edge structure, and micro-X-ray diffraction.

Human hair lipids form a complex mixture of composition close to that of sebum. Part of these lipids appears in an organized state that has been studied by diffraction techniques in the literature. Nevertheless, information on the structure of these lipids remains very scarce due to their low contribution to global hair diffraction pattern. Here we show that appropriate lead treatment considerably enhances organized lipid features observed by microbeam synchrotron radiation diffraction experiments. We attribute these features to the formation of lead soaps of free fatty acids. Specific orientation of hair "lipid crystals" in planes parallel to the hair axis is clearly demonstrated. Inclusion of these lipids in the bulk of the hair shaft is shown by diffraction experiments following removal of the cuticular outermost layer of hair. Moreover, microfluorescence and diffraction experiments are consistent with part of the lipids being present as calcium soaps in native hair. We therefore consider lead fixation as a powerful tool to evaluate the lipid organization in human hair for medical, environmental and archaeological purposes, including lead poisoning.

The emerging electron crystallography is a powerful tool for the determination of the atomic structures of crystals. Many examples have been shown in which electron crystallography has been able to solve even complex structures correctly. However, compared to X-ray crystallography it remains a delicate and time consuming method. Therefore it finds its real application in cases where X-rays are not sufficient to solve the structures. Prominent examples aremulti-phase powders constituted of nanometre sized grains. In this work we present one of these ’’real’’ cases. The sample studied is a nano-sized powder of β-MnO2, which is interesting for applications in batteries, but which contained a few percent of an unexpected phase. Powder X-ray diffraction only showed a few weak peaks in the β-MnO2 spectrum, which were insufficient for a phase determination. Using electron diffraction in a Philips CM300ST transmission electron microscope, we identified the minority phase to be pseudo-cubic α-Mn2O3. The structure determination was done using the diffracted intensities of 16 different zone axes. Since the diffracted intensities are known to be affected by the effects of dynamic diffraction it is not possible to employ the standard methods of crystallography to solve the structure. We have therefore acquired high resolution electron micrographs (HREMs) of the main zone axes of the cubic structure. The Fourier Transform of the HREMs yields the phases of the structure factors, which are much more sensitive to the atomic positions than the intensities. The combination of the measured diffracted intensities and the phases obtained from the HREM allow solving the structure. m18.o01

De plus en plus, les villes-refuges refont surface, mettant à l’actualité les problématiques liées aux migrations et à l’urgence de l’accueil. En Afrique, la prégnance des catastrophes naturelles et des conflits a des conséquences préoccupantes sur les migrations. Le rapport du haut-commissaire des Nations unies pour les réfugiés au sujet des questions relatives aux réfugié·e·s, aux rapatrié·e·s, aux déplacé·e·s et plus largement aux questions humanitaires fait état de 33,4 millions de personnes[footnote]Ce chiffre comprend les réfugié·e·s, les personnes déplacées à l’intérieur de leur propre pays, les demandeurs et demandeuses d’asile, les apatrides et les autres personnes dont la situation s’apparente à celle des réfugié·e·s, ainsi que les personnes retournées dans leur pays d’origine en 2019 et qui reçoivent encore une aide.[/footnote] accueillies en urgence à la fin de l’année 2019. Cela inclut 6,3 millions de réfugié·e·s, 18,5 millions de personnes déplacées à l’intérieur de leur propre pays, 529 600 demandeurs et demandeuses d’asile et 975 000 apatrides[footnote]Assemblée générale des Nations unies, soixante-quinzième session, point 63 de l’ordre du jour provisoire, rapport du haut-commissaire des Nations unies pour les réfugiés, questions relatives aux réfugié·e·s, aux rapatrié·e·s et aux déplacé·e·s et questions humanitaires. Distr. Générale 24 août 2020.[/footnote]. Le Soudan du Sud, la Somalie, la République Démocratique du Congo, le Soudan, la République centrafricaine, l’Érythrée ou le Burundi comptent parmi les pays de provenance du plus grand nombre de réfugié·e·s. Pendant ce temps, en ce qui concerne les pays d’accueil, selon le HCR pour 2019.