Neanderthals see red : production of red powder in the Late Mousterian in Ormesson, France

Poster (2013, February 07)

Les Bossats, near Ormesson, is a newly discovered late Mousterian site dated around 47.000 B.P. by thermoluminescence. The archaeological level, fossilized by loess, revealed a rich industry based on the ... [more ▼]

Les Bossats, near Ormesson, is a newly discovered late Mousterian site dated around 47.000 B.P. by thermoluminescence. The archaeological level, fossilized by loess, revealed a rich industry based on the discoide mode, associated with numerous fragments of red iron-rich rocks. The geological sources were identified by means of SEM-EDX, XRD, Raman spectroscopy, PIXE and by petrographical observation of thin sections. The past mechanical and morphological modifications of the pigment blocks were characterized by macro-photography, microscopy and topographical micro- measures of the used surfaces. It was thus possible to demonstrate that the colouring materials were selected in the neighbouring by the Neanderthals. Fourteen blocks and fragments show different use wears such as facets, grooves and scars. The Neanderthals implemented numerous techniques in order to produce preferentially red powder. The archaeological remains reveal an organized and versatile processing sequence of red ferruginous materials. During the late Mousterian a great phenomenon in expansion in western Europe is remarkable by the much wider exploitation of mineral red and black materials corresponding to technical modifications and divers utilizations under development. [less ▲]

Specialized « ochre » procurement strategies in the Transition context : the red pigments from the Châtelperronian of the Grotte du Renne, Arcy-sur-Cure (France)

Poster (2012, June 01)

In many reports of prehistoric pigment studies, these artefacts are considered as the testimony of past symbolic activities. The first step of the proceeding sequence, that is to say the acquisition of ... [more ▼]

In many reports of prehistoric pigment studies, these artefacts are considered as the testimony of past symbolic activities. The first step of the proceeding sequence, that is to say the acquisition of raw colouring material, is not well described and understood. Physico-chemical (SEM-EDS, XRD, TEM-EDX, µPIXE-µPIGE) and petrological analysis were carried out on the colouring materials excavated in the châtelperronian layers (40000-35000 B.P.) of the French site the Grotte du Renne in Arcy-sur-Cure. The Châtelperronian is one of the transitional techno-complexes, basically one of the last cultures made by Neanderthals in Europe. The physico-chemical data were related to the location of the colouring materials on the site, in association with exceptionally well preserved “hut” structures. It was thus possible to demonstrate that none of these materials, either red or black, was heated before being used, contrary to what had been assumed so far. The supply in colouring materials was as carefully organized as for mineral materials such as flint, for example; they were collected in different geological formations occasionally showing on the surface, close to the cave and at more than 30 km from the cave. The exploitation of these geological sites did not vary during the whole Châtelperronian period, and privileged materials which can easily be ground to powder. The set of colouring minerals from the Grotte du Renne reveals Neanderthals’ in-depth knowledge of mineral materials; they understood perfectly well their properties and qualities, and used them extensively, so that the raw colouring material was part of the livelihood and the Châtelperronian site must have been a literally dazzling sight, all red and black. [less ▲]

TiO2 templated multilayer films used as high efficiency photoelectrode in liquid or solid DSSCs

Conference (2012, April 10)

Mesoporous anatase thin films are very promising materials to act as electrode in dye-sensitized solar cells. Randomly oriented nanocrystalline TiO2 particles are usually used to prepare photoelectrodes ... [more ▼]

Mesoporous anatase thin films are very promising materials to act as electrode in dye-sensitized solar cells. Randomly oriented nanocrystalline TiO2 particles are usually used to prepare photoelectrodes with a thickness of 10-15 µm. Templated-assisted dip-coating techniques are used to obtain thin films with ordered porosity. However, monolayer films prepared by dip-coating from a solution suffer from a low quantity of active material with a limited surface area, leading to poor photovoltaic performances. Therefore a multilayer deposition process is needed to increase the film thickness along with surface area. Multilayer dip-coating procedures have already been reported but are usually characterized by a lack of linearity in the evolution of parameters (roughness, surface area, PV performances) as the number of layer increases. In this study, we investigate a dip-coating-based multilayer deposition technique delaying these limitations. First, the influence of the template on the film organization and porosity is studied in terms of long-range order, percentage of porosity, pore size, surface area and pores connectivity. Different techniques such as transmission electron microscopy (TEM), atmospheric poroellipsometry (AEP) and UV-visible absorption spectroscopy (UV-vis.) have been used to describe the microstructural features of the films. The film exhibiting the highest dye loading was selected and its thickness gradually increased up to 4 µm. Finally, the photovoltaic performances of the thick films (1 to 4 µm) have been evaluated in combination with the N719 dye and a liquid electrolyte and show excellent efficiency (6.1%) when compared to values reported in the literature. Such mesostructured films were compared in terms of photovoltaic performance with TiO2 nanoparticles films, generally used in DSSC. Films were further evaluated by Rutherford Backscattering Spectrometry (RBS) as high performance photoelectrode in solid-state DSSCs, in combination with Z907 dye and Spiro-OMeTAD as solid electrolyte. [less ▲]

Rutherford backscattering analysis of porous thin TiO2 films

in Nuclear Instruments & Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms (2012), 273

The additional energy spread due to sample porosity was implemented in the SIMNRA simulation code, version 6.60 and higher. Deviations of the path length and energy loss distributions from the ones ... [more ▼]

The additional energy spread due to sample porosity was implemented in the SIMNRA simulation code, version 6.60 and higher. Deviations of the path length and energy loss distributions from the ones expected from a Poisson distribution of the number of traversed pores are taken into account. These deviations are due to the interaction of pores at higher pore concentrations by overlap or blocking. The skewnesses of the energy distributions are approximated by two-piece normal distributions with identical first three moments. Propagation of porosity-induced energy spread in thick layers is taken into account. Calculated results are compared to experimental data obtained with thin TiO2 mesoporous films measured by Rutherford backscattering (RBS),transmission electron microscopy (TEM), and atmospheric poroellipsometry. [less ▲]

X-ray production cross-sections measurements for high-energy alpha particle beams: New dedicated set-up and first results with aluminum

in Nuclear Instruments & Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms (2011), 269(24), 29792983

The “IPNAS” laboratory, in collaboration with the “Centre Européen d’Archéométrie” is partly focused on material analysis by means of IBA techniques: PIXE, PIGE and RBS. A new transport beam line has been ... [more ▼]

The “IPNAS” laboratory, in collaboration with the “Centre Européen d’Archéométrie” is partly focused on material analysis by means of IBA techniques: PIXE, PIGE and RBS. A new transport beam line has been developed at our CGR-520 MeV cyclotron to analyze Cultural Heritage objects using these techniques. This facility allows us to produce proton and alpha particle beams with energies up to 20 MeV. A vacuum chamber dedicated to X-ray production and Non-Rutherford cross-section measurements has been recently constructed. After determination of the chamber’s geometry for X-ray detection using thin foils of several elements (11 ⩽ Z ⩽ 82) and 3 MeV proton beams, the measurement of the X-ray production cross-sections in the 6–12 MeV energy range has started using alpha particle beams on light element targets. These experiments contribute to the filling a serious lack of experimental values for alpha particles of this particular energy range in databases. The recent decision to focus our work on the alpha particle interaction with light elements was taken because of the high interest of the low Z elements in the field of archaeometry. [less ▲]

L'utilisation du fer dans la construction médiévale mosane : explications et premiers repères d'une évolution

Conference (2011, April 11)

The development of a new comparative approach establishing a link between the evaluation of the quantity of barks used in a roof frame and the volume of wood present in this same attic allows the ... [more ▼]

The development of a new comparative approach establishing a link between the evaluation of the quantity of barks used in a roof frame and the volume of wood present in this same attic allows the acquisition of essential information for the apprehension of the economical, the technical and the social contexts in which a timber frame was drawn up. By carrying out this kind of comparison in a systematic way in about thirty attics of religious buildings dispersed in the Walloon region (Belgium), the evolution of these contexts develops step by step since 12th until 18thcentury and highlights phenomena which influence the methods of constructions of the carpenters, like the appearance of the saw or the rarefaction of the forest resources. The confrontation of this result with the evolution of the volume of iron considered in the attics reveals the catch of importance of this material in function of the time and of the architectural principles. Iron appears in the roof frames of our areas in the same time that the advent of the Gothic architecture in link with the increase of the roof’s dimensions. Its employment generalizes then knows a real expansion at the 17th century because of the rarefaction of the forest resources but also because the preindustrial techniques allow it. [less ▲]

Verre Mérovingien dans la vallée Mosane - apport de l'archéométrie à l'étude des techniques et à l'histoire économique

Conference (2011, April)

Couches d'oxydation et patines intentionnelles des bronzes

Book published by Editions universitaires europeennes (2011)

Les couches d'oxydation présentes à la surface des alliages cuivreux d'objets du patrimoine culturel sont très riches d'informations. Elles peuvent renseigner sur l'aspect d'origine de l'objet et sur son ... [more ▼]

Les couches d'oxydation présentes à la surface des alliages cuivreux d'objets du patrimoine culturel sont très riches d'informations. Elles peuvent renseigner sur l'aspect d'origine de l'objet et sur son état de conservation. Elles sont souvent de nature très complexe et leur analyse est très délicate car elle est soumise à des contraintes sévères de préservation. Nous nous sommes intéressés aux couches provenant d'oxydations à haute température et aux patines intentionnelles antiques. L'oxydation à haute température du système cuivre-étain a été étudiée de manière approfondie et nous avons proposé un modèle mettant en évidence le rôle inhibiteur de l'étain. Nous avons également étudié les patines intentionnelles antiques qui sont le résultat de traitements chimiques effectués par l'artisan pour modifier l'aspect et la couleur du matériau métallique. Pour cela nous avons analysé un corpus exceptionnel d'objets de musée. Ces analyses ont permis de réaliser des avancées importantes dans la connaissance de ces objets et de ces techniques, mais aussi dans le domaine de l'histoire des techniques et stylistique dans l'Antiquité méditerranéenne. [less ▲]

TiO2 multilayer thick films (up to 4 μm) with ordered mesoporosity: Influence of template on the film mesostructure and use as high efficiency photoelectrode in DSSCs

in Journal of Materials Chemistry (2011), 21(20), 7356-7363

Mesoporous templated anatase thin films are very promising materials to act as photoelectrode in dye-sensitized solar cell. Templated-assisted dip-coating techniques are used to obtain thin films with ... [more ▼]

Mesoporous templated anatase thin films are very promising materials to act as photoelectrode in dye-sensitized solar cell. Templated-assisted dip-coating techniques are used to obtain thin films with ordered porosity. However, monolayer films are very thin and suffer from a low quantity of active material, leading to poor photovoltaic performances. In this paper, a dip-coating-based multilayer deposition technique is reported. First, we have studied the influence of the template on the film organization and porosity in terms of long-range order, percentage of porosity, pore size and pores connectivity. Different techniques such as transmission electron microscopy (TEM), atmospheric poroellipsometry (AEP) and UV-visible absorption spectroscopy (UV-vis.) have been used to describe the microstructural features of the films with a thickness of 1 µm. The film exhibiting the highest dye loading was selected and its thickness gradually increased up to 4 µm. Finally, the photovoltaic performances of the thick films (1 to 4 µm) have been evaluated in combination with the N-719 dye and show excellent efficiency (6.1%) when compared to values reported in the literature. Such mesostructured films are compared in terms of photovoltaic performance with TiO2 nanoparticles films, generally used in DSSC. [less ▲]

TiO2 mesoporous thin films studied by Atmospheric Ellipsometric Porosimetry: A case of contamination

in Microporous & Mesoporous Materials (2011), 147

Anatase mesoporous TiO2 thin films are frequently prepared by surfactant templating to control porosity development and Atmospheric Ellipsometric Porosimetry is a reliable and fast technique allowing the ... [more ▼]

Anatase mesoporous TiO2 thin films are frequently prepared by surfactant templating to control porosity development and Atmospheric Ellipsometric Porosimetry is a reliable and fast technique allowing the determination of the porosity of such films. After prolonged exposition to high-vacuum (6×10-6 mbar), the films porosity exhibits a degraded behavior during porosimetric measurements, indicating a vacuum-induced modification. The main effect resulting from such exposition to high-vacuum is a wet- tability modification of the films, resulting in an increase of the hydrophobic character of the TiO2 surface. This evolution induces non-correct results in porosimetric measurements due to the fact that the contact angle parameter needed to calculate the pore size distribution is highly different from the reference films. A surface contamination explains such modifications and a restoration of the films is obtained by using ultraviolet treatment. [less ▲]