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Publications

Publications list back to 2001

A little click on the journal cover and there’s the paper, provided you are eligible to download it.


Year 2013


Year 2012

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Applied Geochemistry

Microbial diversity in contaminated soils along the T22 trench of the Chernobyl experimental platform

Applied Geochemistry, 27 (7), 1375-83, 2012

V. Chapon, L. Piette, M.-H. Vesvres, F. Coppin, C. Le Marrec, R. Christen, N . Theodorakopoulos, L. Fevrier, S. Levchuk, A. Martin-Garin, C. Berthomieu, C. Sergeant

The diversity of bacterial communities exposed to radioactive contamination in Chernobyl soils was examined by a combination of molecular and culture-based approaches. A set of six radioactive soil sam- ples, exhibiting high levels of 137Cs contamination, were collected from the T22 trench. Three samples were also collected in nearby soils with low contamination. Complex bacterial community structures were observed in both highly and weakly contaminated samples, using a molecular approach targeting the 16S rRNA gene. However, the presence of specific populations within samples from highly contaminated soils could not be revealed by statistical analysis of the DGGE profiles. More than 200 culturable isolates, representative of dominant morphotypes, were grouped into 83 Operational Taxonomic Units (OTUs) and affiliated to Firmicutes, Actinobacteria, Alpha-, Beta-, Gamma-Proteobacteria and Bacteroïdetes. No specific pattern linked to contamination was observed for these culturable bacteria. The results show that both highly and weakly contaminated soils host a wide diversity of bacteria, suggesting that long term exposure to radionuclides does not lead to the extinction of bacterial diversity. .

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Applied Geochemistry

Stages of evolution of a Toarcian compacted claystone around galleries excavated between 1 and 124 years ago by the study of noble gases dissolved in pore water at the Tournemire Underground Research Laboratory (France)

Applied Geochemistry, 27 (7), 1403–1416, 2012

Bernard Lavielle, Jean-Michel Matray, Bertrand Thomas, Alexandre Dauzères, Fethi Bensenouci, Eric Gilabert

The purpose of this work is to study the diffusion properties in an argillaceous formation and how these properties change after the excavation of galleries, over a long period. The Tournemire Underground Research Laboratory (URL) located in Aveyron (France) offers the unique opportunity to investigate different stages of the evolution of the so-called Excavation Damaged Zone (EDZ) over a period of about 124 a. Four horizontal boreholes parallel to the bedding and one vertical borehole were drilled in order to study diffusion transport in the EDZ in both directions in galleries excavated 124, 13, 6, and 1 a ago, respectively. Noble gases dissolved in the pore water of 47 core samples were extracted in order to establish precise depth profiles. Mainly produced in situ by decay of U and Th, radiogenic He accumulates in the pore water of rocks and escapes toward the gallery, allowing a characterization of the diffusive transport in the EDZ and its evolution with time. For the oldest gallery (1882–1888), core mapping reveals an EDZ well developed with fractures up to a depth of 1.8 m. In this zone, all radiogenic He has been lost and at the same time heavy noble gases are trapped in the rock with an enrichment of Xe relative to Kr and of Kr relative to Ar. From 1.8 m, He concentration increases with depth to reach a plateau at about 3.5 m corresponding to a concentration normally found in the unaltered zone. Considering diffusive transport of the radiogenic He to the EDZ, model calculations allowed proposing transport properties in the unfractured and undisturbed zone (UZ) with a pore diffusion coefficient Dp of 1x10[-10] m2/s deduced from the best-fit curve to experimental data and a mean porosity of 0.1 obtained form petrophysical measurements. The most recent gallery (2008) did not show any evidence of EDZ at depths greater than 7.5 cm. A fracture located around 0.75 m, possibly of tectonic origin, induced large advection and diffusion losses of He on both sides in the next 50 cm. Excesses of Ar, Kr and Xe are found, suggesting diffusion of air from the gallery associated with He losses. The 6-a-old gallery is clearly influenced by fractures of tectonic origin increasing the EDZ thickness of 0.7 m up to a Damaged Zone of 1.8 m. Based on the He concentration profile, the 13-a-old gallery (1996) has a net EDZ of 1.2 m, larger than the 0.7 m deduced from the structural analysis by core mapping, followed by a disturbed zone of up to 3.5 m that could represent an intermediate stage before the development of fractures in the EDZ. The vertical borehole drilled in the same gallery shows a less extensive damaged zone (1.4 m) and allows the determination of a Dp of 3x10[-11] m2/s taking into account the anisotropy relative to the stratification plane. The rare gas analysis has, therefore, enabled confirmation and better description of the net time-dependent evolution of the EDZ around drifts in the argillaceous Tournemire site: no obvious EDZ for the 1-a gallery (2008), 1.2 m width for the 13-a-old gallery (1996), and 2 m width for the century-old tunnel. The occurrence of a disturbed and unfractured zone (dZ) around the 13-a-old gallery undetected by structural studies and geophysical methods clearly demonstrates the power of radiogenic He in assessing the transport properties around drifts excavated at different ages in compacted clay rocks. .

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Journal of Environmental Radioactivity

Evidence of 131I and 134,137Cs activities in Bordeaux, France due to the Fukushima nuclear accident

Journal of Environmental Radioactivity, Vol. 114, p.61, 2012

F. Perrot, Ph. Hubert, Ch. Marquet, M.S. Pravikoff, P. Bourquin, H. Chiron, P.-Y. Guernion, A. Nachab

Following the Fukushima nuclear accident, low-background gamma spectrometry measurements were performed with HPGe detectors at the PRISNA platform located at the CENBG laboratory in Bordeaux, France. Different kinds of samples were collected and measured between March 26 and May 14, 2011. The first fission product observed was 131I with maximum activity values of 2.4 mBq/m3 in atmospheric dusts in air, 3.5 Bq/L in rain water, 15 Bq/kg in grass and 0.9 Bq/L in cow milk. The 134,137Cs isotopes were also detected in air and in grass at a maximum level of 0.2 mBq/m3 and 0.7 Bq/kg respectively, around one order of magnitude less than 131I activity, but they were below detection limits in the other samples. All these activity values were consistent with others measured in France by IRSN and were well below those reported in May 1986 after the Chernobyl accident.

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Year 2011

Biogeochemical processes in a clay formation in situ experiment: Part D- Microbial analyses - Synthesis of results

Applied Geochemistry, 26, 980-989, 2011

S. Stroes-Gascoyne, C. Sergeant, A. Schippers, C.J. Hamon, S. Nèble, M.-H. Vesvres, V. Barsotti, S. Poulain, C. Le Marrec

The purpose of the Porewater Chemistry (PC) experiment at the Mont Terri (MT) Underground Rock Laboratory (URL) was to measure geochemical parameters, such as pH, Eh and pCO2, in the porewater of the Opalinus Clay formation. Although the PC experiment was designed and implemented carefully from a geochemical perspective, conditions were not sterile and some microbial and nutrient contamination likely occurred. Microbial activity in the added synthetic porewater in the borehole was apparent shortly after initiation of the experiment and affected the geochemical parameters observed in the porewater. This paper summarizes the results from microbial analyses of post-termination PC water and overcore clay samples, conducted to attempt to elucidate the role of microbial activity in the evolution of the geochemical conditions in the PC experiment. Microbial analyses of the PC borehole water, and of clay overcore samples from around the borehole, were carried out at three laboratories and included both molecular biology and culturing methods. Results indicated the presence of heterotrophic aerobic and anaerobic organisms that resulted likely from the initial, non-sterile conditions, sustained by suspected contamination with organic matter (glycerol, acetone). The results also indicated the presence of nitrate-reducers, iron-reducers, sulphate-reducers and methanogens (i.e., Bacteria as well as Archaea), suggesting a reducing environment with Fe(III)- and sulphate reduction and methanogenesis occurring in the PC water and adjacent clay. A black precipitate containing pyrite (identified by XRD and SEM) and a strong H2S smell in the porewater confirmed the occurrence of sulphate reduction. Microorganisms identified in the porewater included Pseudomonas stutzeri, Bacillus licheniformis, Desulfosporosinus spp. and Hyphomonas spp. Species identified in enrichment cultures from the overcore samples included Pseudomonas stutzeri, three species of Trichococcus spp., Caldanaerocella colombiensis, Geosporobacter subterrenus and Desulfosporosinus lacus. Overall the results indicated a thriving microbial community in the PC water and adjacent clay in contrast to “undisturbed” Opalinus Clay for which limited evidence for a small viable microbial community was given in a previous study (Poulain et al. 2008 Geomicrobiol. J. 25(5): 240- 249; Stroes-Gascoyne et al. 2007 Geomicrobiol. J. 24, 1-17; Mauclaire et al. 2007 Physics and Chemistry of the Earth 32, 232-240).

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Year 2010

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Applied Geochemistry

Establishing constraints on groundwater ages with 36Cl, 14C, 3H, and noble gases: A case study in the eastern Paris basin, France

Applied Geochemistry, Volume 25, Issue 1, January 2010, Pages 123-142

ErratumApplied Geochemistry, Volume 25, Issue 7, July 2010, Pages 1092-1093

Véronique Lavastre, Corinne Le Gal La Salle, Jean-Luc Michelot, Sophie Giannesini, Lucilla Benedetti, Joël Lancelot, Bernard Lavielle, Marc Massault, Bertrand Thomas, Eric Gilabert, Didier Bourlès, Norbert Clauer, Pierre Agrinier

Groundwaters from the Tithonian/Kimmeridgian, Oxfordian and Upper Dogger aquifers, within the eastern part of the Paris basin (France), were characterised using 3H, 14C and 36Cl, and noble gases tracers, to evaluate their residence times and determine their recharge period. This information is an important prerequisite to evaluating the confinement properties of the Callovo-Oxfordian clay formation sandwiched between the Oxfordian aquifer and the Dogger aquifer, currently being investigated by the French nuclear waste management agency (Andra) for radioactive waste disposal. Data presented in this paper are used to test 4 hypotheses.


Year 2009

Human transferring expressed in transgenic Rd10 mice or ip injected Rd10 mice protects retinal photoreceptors degeneration

Molecular Vision, 16, 2612-25, 2010

E. Picard, L. Jonet, C. Sergeant, M.H. Vesvres, F. Behar-Cohen, Y. Courtois, J.C. Jeanny

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Applied Geochemistry

Establishing constraints on groundwater ages with 36Cl, 14C, 3H, and noble gases: A case study in the eastern Paris basin, France

Applied Geochemistry, Volume 25, Issue 1, January 2010, Pages 123-142

ErratumApplied Geochemistry, Volume 25, Issue 7, July 2010, Pages 1092-1093

Véronique Lavastre, Corinne Le Gal La Salle, Jean-Luc Michelot, Sophie Giannesini, Lucilla Benedetti, Joël Lancelot, Bernard Lavielle, Marc Massault, Bertrand Thomas, Eric Gilabert, Didier Bourlès, Norbert Clauer, Pierre Agrinier

Groundwaters from the Tithonian/Kimmeridgian, Oxfordian and Upper Dogger aquifers, within the eastern part of the Paris basin (France), were characterised using 3H, 14C and 36Cl, and noble gases tracers, to evaluate their residence times and determine their recharge period. This information is an important prerequisite to evaluating the confinement properties of the Callovo-Oxfordian clay formation sandwiched between the Oxfordian aquifer and the Dogger aquifer, currently being investigated by the French nuclear waste management agency (Andra) for radioactive waste disposal. Data presented in this paper are used to test 4 hypotheses.


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Journal of Nuclear Materials

Behaviour of helium after implantation in molybdenum

J. Nucl. Mat. 385 (2009) 294-298

C. Viaud, S. Maillard, G. Carlot, C. Valot, E. Gilabert, T. Sauvage, C. Peaucelle and N. Moncoffre

This study deals with the behaviour of helium in a molybdenum liner dedicated to the retention of fission products. More precisely this work contributes to evaluate the release of implanted helium when the gas has precipitated into nanometric bubbles close to the free surface. A simple model dedicated to calculate the helium release in such a condition is presented. The specificity of this model lays on the assumption that the gas is in equilibrium with a simple distribution of growing bubbles. This effort is encouraging since the calculated helium release fits an experimental dataset with a set of parameters in good agreement with the literature.

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Comptes Rendus Physique

Radioactivity measurements applied to the dating and authentication of old wines

Comptes Rendus Physique, Volume 10, Issue 7, September 2009, Pages 622-629

Ph. Hubert, F. Perrot, J. Gaye, B. Médina, M.S. Pravikoff

For many years the neutrino group in the CENBG has been involved in the development of low background γ -ray spectrometers, based on the use of HPGe crystals. When applied to radioactivity measurements of wine in bottles, it has been shown that besides the well-known isotope 40K, the wine contains also trace amounts of 137Cs (less than 1 Bq/l) with an activity depending on the vintage. This technique has thus led to the possibility to date the wine bottles of vintages between 1952 and ∼1980 and to verify the year written on the label or on the cork. Since the measurements do not require opening the bottle, the technique has also proved to be very useful for detecting counterfeit wines of the XIXth century and first half of the XXth century.

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Tchernobyl : des bordelaises cherchent à identifier des bactéries résistantes à la radioactivité (article grand public)

H20 : la revue des Sciences et de l’Industrie en Aquitaine, 95, 2009 (et) Site WEB de Cap Sciences Bordeaux

A. Marsat (journaliste), C. Sergeant, C. Le Marrec

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Quand des bactéries vivent en conditions extrêmes…

Signet Visage des Sciences (Fête de la Science 2009)

C. Sergeant

On sait maintenant que la vie peut se développer dans des conditions très variées, y compris extrêmes (très fortes températures : plus de 110°C; très fortes pressions : à plus de 4000 m sous la mer; en présence de très peu d’eau et même dans un milieu très radioactif). C’est à la découverte et à l’étude du métabolisme de ce type de bactéries que l’équipe de Claire Sergeant s’intéresse. Ainsi, elle a pu mettre en évidence deux espècesde bactéries jusque là inconnues, dans une argile très ancienne et très compacte étudiée dans le cadre des recherches sur le stockage des déchets radioactifs. Les expériences en cours sur les populations bactériennes de sols de régions proches de Tchernobyl, contaminés par des radioéléments, vont permettre de mieux comprendre les mécanismes qui leur permettent de s’adapter à ces conditions inhospitaières et pourraient mener à la découverte de souches bactériennes utilisables .

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Year 2008

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Meteoritics & Planetary Science

The complex exposure histories of the Pitts and Horse Creeck iron meteorites : implications for meteorite delivery models

Meteoritics & Planetary Science, vol. 43, Issue 8, p.1321-1332

K. C. Welten, K. Nishiizumi, B. Lavielle, M. W. Caffee, D. J. Hillegonds, R. C. Finkel, D. Kollar and J. Masari

The concentrations of cosmogenic radionuclides and noble gases in Pitts (IAB) and Horse Creek (ungrouped) provide unambiguous evidence that both irons have a complex exposure history with a first-stage irradiation of 100–600 Myr under high shielding, followed by a second-stage exposure of ˜1 Myr as small objects. The first-stage exposure ages of ˜100 Myr for Horse Creek and ˜600 Myr for Pitts are similar to cosmic-ray exposure ages of other iron meteorites, and most likely represent the Yarkovsky orbital drift times of irons from their parent bodies in the main asteroid belt to one of the nearby chaotic resonance zones. The short second-stage exposure ages indicate that collisional debris from recent impact events on their precursor objects was quickly delivered to Earth. The short delivery times suggests that the recent collision events occurred while the precursor objects of Horse Creek and Pitts were either very close to the chaotic resonance zones or already in Earth-crossing orbits. Since the cosmogenic noble gas records of Horse Creek and Pitts indicate a minimum radius of a few meters for the precursor objects, but do not exclude km-sized objects, we conclude that these irons may represent fragments of two near-Earth asteroids, 3103 Eger and 1986 DA, respectively. Finally, we used the cosmogenic nuclide concentrations in Horse Creek, which contains 2.5 wt% Si, to test current model calculations for the production of cosmogenic 10Be, 26Al, and neonisotopes from iron, nickel, and silicon.

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Geomicrobiology Journal

Microbial Investigations of Opalinus Clay, an Argillaceous Formation as a Potential Host Rock under Evaluation for a Radioactive Waste Repository

Geomicrobiology Journal, 25(5) (2008) 240-249

Poulain S., Sergeant C., Simonoff M., Le Marrec C., Altmann S.

Various deep, compact, sedimentary formations have been studied in recent years as potential host rock for a repository for high-level, long-lived radioactive waste. Considering that microbial activities may influence radionuclide chemistry and migration in such environments, we investigated the potential presence of microorganisms in the Opalinus Clay formation, from unperturbed sediment samples (i.e., not affected by gallery excavation and borehole drilling) recovered under aseptic conditions in the Mont Terri Underground Rock Laboratory (Switzerland). A combination of molecular biology techniques and a cultivation-based approach suggested the presence of a few sparse autochthonous microbial cells in the Opalinus Clay. For the first time, ribosomal RNA (rRNA) genes were sequenced from enrichment cultures from such samples. The results suggested that at least two of the bacterial strains isolated were likely unknown species of the Sphingomonas and Alicyclobacillus genera, as their fully-sequenced 16S-rRNA genes shared less than 97% similarity with validly published sequences. Early genetic divergence occurring after physical isolation of bacterial ancestors in the geosphere by the sedimentation process or following later geological events may have resulted in the generation of particular taxa in the subsurface.

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Nuclear Instruments and Methods in Physics Research B

Cross sections for the production of helium, neon, and argon isotopes by proton-induced reactions on iron and nickel

Nucl. Instr. Meth. Phys. Res. B266 (2008)2-12

K. Ammon, I. Leya, B. Lavielle, E. Gilabert, J.-C. David, U. Herpers, and R. Michel

We measured integral thin target cross sections for the proton-induced production of 3He, 4He, 21Ne, 22Ne, 36Ar and 38Ar from Fe and Ni from the respective reaction thresholds up to 1.6 GeV. The production of noble gas isotopes, especially 4He, from Fe and Ni is of special importance for design studies of accelerator driven systems and/or energy amplifier, because Fe is the main structural material in almost every design study. Furthermore, the cross sections are needed to establish the first physical model calculations for the production of cosmogenic nuclides in iron meteorites. As a result of our new measurements there now exist for both target elements a complete and consistent database for the production of noble gas isotopes. The experimental data are compared to results from the theoretical nuclear model codes INCL4/ABLA and TALYS. This comparison clearly demonstrates again that experimental data are still needed because the predictive power of nuclear model codes, though permanently improving, does.

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Journal of Nuclear Materials

Study of radiogenic helium diffusion in the β-Thorium Phosphate Diphosphate ceramic

Journal of Nuclear Materials 373 (2008) 112-118

A. Özgümüs, E. Gilabert, N. Dacheux, C. Tamain and B. Lavielle

\beta-Thorium phosphate diphosphate polycrystalline ceramic is considered as a promising candidate for the immobilization of actinides in the field of a long-term storage. In order to study the behavior of the ceramic in relation with the evacuation of helium produced by actinides and daughters disintegrations, the release of radiogenic helium from a sintered pellet aged over an about six year period was studied by thermal desorption and high resolution mass spectrometry. The apparent diffusion coefficients are determined for different annealing sequences and are approximately the same for zircon and britholite at low temperature and uranium dioxide ceramic at high temperature. The apparent diffusion coefficients are found to be (7 ± 3) · 10-22 m2 s-1 and (1.5 ± 0.5) · 10-20 m2 s-1 at 20°C and 120°C, respectively. The activation energy for the apparent diffusion process encompassing both volume and inter-granular diffusion is estimated at 45 ± 15 kJ mol-1 in the studied temperature range (20–1020°C).


Year 2007

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pas de couverture

Comportement physico-chimique de l’uranium et du technétium dans le cycle du combustible nucléaire actuel et futur

Journ. Chim. Russe (J. de la Soc. De Chim. D.I. Mendeleïev), 51(6) (2007) 11-23

Peretrukhin V.F., Moisy Ph., Maslennikov A.G., Sergeant C., Guerman K.E., David F., Fourest B., Simonoff M., Tsivadze A.J., Lecomte M.

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Comptes Rendus de l\’Académie des Sciences

Microorganisms and migration of radionuclides in environment

Comptes Rendus Chimie, Volume 10, Issues 10-11, October-November 2007, Pages 1092-1107

Monique Simonoff, Claire Sergeant, Sébastien Poulain, Michael S. Pravikoff

Amongst all the fission fragments, actinides and activation products coming from the nuclear energy processes, a dozen radionuclides are a hazard for Man and environment, due to their half-life and toxicity. For the last 3.5e4 billion years (Ga), microorganisms have been present on Earth in all sorts of surroundings, even the most hostile ones, characterized by extreme pH, temperature and/or radioactivity. To grow and multiply, they developed enzymatically induced oxido-reduction reactions by coupling reduction of metals/metalloids with oxidation of organic matter, which, in turn, may change soluble forms of radionuclides or stable elements into non-soluble forms. When this happens, microorganisms contribute to fix the radionuclides and prevent dissemination.

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Applied Microbiology and Biotechnology

Characterization of Technetium(VII) reduction by cell suspensions of thermophilic bacteria and archae

Applied Microbiology and Biotechnology 76 (2007) 467-472

Chernyh N.A., Gavrilov S.N., Sorokin V.V., German K.E., Sergeant C., Simonoff M., Robb F., Slobodkin A.I.

Washed cell suspensions of the anaerobic hyperthermophilic archaea Thermococcus pacificus and Thermoproteus uzoniensis and the anaerobic thermophilic gram-positive bacteria Thermoterrabacterium ferrireducens and Tepidibacter thalassicus reduced technetium [99Tc(VII)], supplied as soluble pertechnetate with molecular hydrogen as an electron donor, forming highly insoluble Tc(IV)-containing grayish-black precipitate. Apart from molecular hydrogen, T. ferrireducens reduced Tc(VII) with lactate, glycerol, and yeast extract as electron donors, and T. thalassicus reduced it with peptone. Scanning electron microscopy and X-ray microanalysis of cell suspensions of T. ferrireducens showed the presence of Tc-containing particles attached to the surfaces of non-lysed cells. This is the first report on the reduction in Tc(VII) by thermophilic microorganisms of the domain Bacteria and by archaea of the phylum Euryarchaeota.

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Geomicrobiology Journal

Microbial community analysis of Opalinus Clay drill core samples from the Mont Terri Underground Research laboratory, Switzerland

Geomicrobiology Journal 24 (2007) 1-17

Stroes-Gascoyne S., Schippers A., Schwyn B., Poulain S., Sergeant C., Le Marrec C., Simonoff M., Altmann S., Nagaoka T., Mauclaire L., McKenzie J., Daumas S., Vinsot A., Beaucaire C., Matray J. M.

Opalinus Clay is a candidate host rock for a high-level radioactive waste repository in Switzerland. Microbial metabolism and its by-products could affect the physical and (geo)chemical conditions in such a repository. This study investigated the occurrence of indigenous microbes, their community size and-structure in an Opalinus Clay core from the Mont Terri Underground Research Laboratory, Switzerland, drilled with aseptic techniques. Core sub-samples were distributed to five laboratories, where they were analysed with microscopy, culture-and molecular biology techniques. Evidence supporting a viable microbial community in Opalinus Clay included: five positive culture results (including for sulphate-reducing bacteria, SRB) out of 20 culture attempts; extraction of 64 ng phospholipid fatty acids (PLFA) per g clay, suggesting the presence of viable cells; detection of PLFA biomarkers for anaerobic Gram-negative bacteria and SRB; and the presence of sufficient nutrients to support growth of indigenous and non-indigenous microorganisms for two months. Evidence against a thriving microbial community in Opalinus Clay included: 15 negative culture results out of 20 attempts; lack of cells by application of microscope techniques (phase contrast, AODC, CARD-FISH); consistent failure to extract PCR-amplifiable DNA from the core; the presence of 14 times higher amounts of lipids indicative of cell debris than those indicative of viable cells (PFLA); very small pore sizes; and very low water content. The combined results of this study (and evidence from other studies in comparable environments) suggest that unperturbed Opalinus Clay appears to contain only a small viable microbial community, which is probably metabolically almost inactive (dormant), due to space and water restrictions. However, any disturbances that would provide space, water and nutrients, as would be the case during repository excavation and construction, could revive the dormant organisms, unless the host rock was kept intact.

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Ultrasonics Sonochemistry

Comparative study of sonochemical reactors with different geometry using thermal and chemical probes

Ultrasonics Sonochemistry 14 (2007) 330-336

Nikitenko S. I., Le Naour C., Moisy P.

Laboratory scale 20 kHz sonochemical reactors with different geometries have been tested using thermal probes, the kinetics of H2O2 formation, and the kinetics of diphenylmethane (DPhM) sonochemical darkening. Results revealed that the overall sonochemical reaction rates in H2O and DPhM are driven by the total absorbed acoustic energy and roughly independent the geometry of the studied reactors. However, the sonochemical efficiency, defined as g = VG/S, where G is a sonochemical yield of H2O2, V is a volume of sonicated liquid, and S is a surface of the sonotrode, was proved to increase with the decrease of S. This phenomenon was explained by growing of the maximum cavitating bubble size with ultrasonic intensity and its independence towards the specific absorbed acoustic power. For the cleaning bath reactor the kinetics of the sonochemical reactions in H2O and DPhM depends strongly on the reaction vessel materials: the reaction rates decreased with the increase of the materials elasticity. Kinetic study of H2SO4 sonolysis using a sonoreactor without direct contact

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Bulletin de la Société Géologique de France

The contribution of water geochemistry to the understanding of the regional hydrogeological system

Mémoires de la Société géologique de France 178 (2007) 91-114

Buschaert S., Giannesini S., Benedetti L., Lavastre V., Gaucher E. C., Lacroix M., Lavielle B., Michelot J.-L., France-Lanord C., Bourles D., Finkel R., Lancelot J., Dewonck S., Vinsot A.

The main results of hydrogeochemical investigations around the Andra Underground Research Laboratory (URL) located in eastern part of the Paris Basin are described hereafter. Groundwater data (chemistry and isotopic composition) have been acquired all around the URL to determine the origin and residence time of water circulations in limestones of Oxfordian and Dogger age, surrounding the Callovo-Oxfordian argillites, and to determine the hydrogeologic role of the argillites regarding aquifers. The main geochemical result is that deep groundwaters from Oxfordian and Dogger limestones are significantly dissimilar to waters of superficial formations. Chemical and isotopic compositions indicate differences between these two deep-aquifer groundwaters. Groundwaters from the Oxfordian limestone are typically meteoric while some groundwater samples from Dogger limestone may correspond to a mixture of meteoric-brine water. Geochemical and hydrogeologic evidence indicates that these deep samples are old groundwaters. Water from Oxfordian limestone may have residence times of the order of 104-105 year, while the age of water in the Dogger is probably older. Natural tracer studies in the overall sedimentary series indicate that the argillites allow chlorine transfer by diffusion from the Dogger to Oxfordian aquifer. For the porewater of argillites, the approach is totally different: geochemical modelling has been developed to define the chemistry which relies entirely on a complete set of measured physical and chemical parameters.


Year 2006

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Nuclear Instruments and Methods in Physics Research B

Three-dimensional densitometry imaging of diatom cells using STIM tomography

Nuclear Instruments and Methods in Physics Research B 249 (2006) 653-659 Seventeenth International Conference on Ion Beam Analysis, Séville (2006)

C. Habchi, D.T. Nguyen, G. Devès, S. Incerti, L. Lemelle, P. Le Van Vang, Ph. Moretto, R. Ortega, H. Seznec, A. Sakellariou, C. Sergeant, A. Simionovici, M.D. Ynsa, E. Gontier, M. Heiss, T. Pouthier, A. Boudou, F. Rebillat

Scanning transmission ion microscopy tomography (STIM-T) was carried out on diatom cells with the aim of displaying their 3D structure and performing density measurements on their silica skeleton. Two software packages were compared for data reduction: TomoRebuild, based on a simple filtered backprojection algorithm, and DISRA, an iterative program. Silicon carbide microfibres of known density were also analysed as reference specimens. Similar results were obtained with both algorithms, demonstrating the ability of STIM-T to provide density measurements at the cell level without requiring any standard calibration samples. This unique feature stresses the interest of STIM-T to accurately normalise X ray emission micro-tomography data from synchrotron radiation (SXRF: synchrotron radiation X-ray fluorescence) or ion beam sources (PIXE: particle induced X-ray emission). Possible enhancements of the DISRA code are discussed in order to facilitate its use for the reconstruction of future PIXE/STIM tomography data. A ‘‘nanoprobe’’ coupled to a Singletron accelerator, allowing a spatial resolution of a few tens of nanometers, is going to be built in the coming months at the Centre d’Etudes Nucléaires de Bordeaux Gradignan (CENBG). This new facility will bring promising applications in imaging and analysis at the sub-cellular level.

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Radiochimica Acta

Technetium sorption by stibnite from natural water

Radiochimica Acta 94 (2006) 665-669

Peretroukhine V. F., Sergeant C., Devès G., Poulain S., Vesvres M.-H., Simonoff M.

The main results of hydrogeochemical investigations around the Andra Underground Research Laboratory (URL) located in eastern part of the Paris Basin are described hereafter. Groundwater data (chemistry and isotopic composition) have been acquired all around the URL to determine the origin and residence time of water circulations in limestones of Oxfordian and Dogger age, surrounding the Callovo-Oxfordian argillites, and to determine the hydrogeologic role of the argillites regarding aquifers. The main geochemical result is that deep groundwaters from Oxfordian and Dogger limestones are significantly dissimilar to waters of superficial formations. Chemical and isotopic compositions indicate differences between these two deep-aquifer groundwaters. Groundwaters from the Oxfordian limestone are typically meteoric while some groundwater samples from Dogger limestone may correspond to a mixture of meteoric-brine water. Geochemical and hydrogeologic evidence indicates that these deep samples are old groundwaters. Water from Oxfordian limestone may have residence times of the order of 104-105 year, while the age of water in the Dogger is probably older. Natural tracer studies in the overall sedimentary series indicate that the argillites allow chlorine transfer by diffusion from the Dogger to Oxfordian aquifer. For the porewater of argillites, the approach is totally different: geochemical modelling has been developed to define the chemistry which relies entirely on a complete set of measured physical and chemical parameters.


Year 2005

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Nuclear Instruments and Methods in Physics Research B

Calcium, potassium, iron, copper and zinc concentrations in the white and gray matter of the cerebellum and corpus callosum in brain of four genetic mouse strains

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 231, Issues 1-4, April 2005, Pages 234-238

C. Sergeant, M.H. Vesvres, G. Devès, F. Guillou

In the central nervous system, metallic cations are involved in oligodendrocyte maturation and myelinogenesis. Moreover, the metallic cations have been associated with pathogenesis, particularly multiple sclerosis and malignant gliomas. The brain is vulnerable to either a deficit or an excess of available trace elements. Relationship between trace metals and myelinogenesis is important in understanding a severe human pathology : the multiple sclerosis, which remains without efficient treatment. One approach to understand this disease has used mutant or transgenic mice presenting myelin deficiency or excess. But to date, the concentration of trace metals and mineral elements in white and gray matter areas in wild type brain is unknown. The aim of this study is to establish the reference concentrations of trace metals (iron, copper and zinc) and minerals (potassium and calcium) in the white and gray matter of the mouse cerebellum and corpus callosum. The brains of four different genetic mouse strains (C57Black6/SJL, C57Black6/D2, SJL and C3H) were analyzed. The freeze-dried samples were prepared to allow PIXE (Proton-induced X-ray emission) and RBS (Rutherford backscattering spectrometry) analyses with the nuclear microprobe in Bordeaux. The results obtained give the first reference values. Furthermore, one species out of the fours testes exhibited differences in calcium, iron and zinc concentrations in the white matter.


Year 2004

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Médecine tropicale

Sélénium plasmatique et cardiomyopathie péripartum à Bamako (Mali)

Médecine tropicale : revue du Corps de santé colonial. 64, 2 (2004) 151-154

A. Cénac, K. Touré, M. B. Diarra, C. Sergeant, Y. Jobic, K. Sanogo, M. Dembele, V. Fayol, M. Simonoff

L’insuffisance cardiaque péripartum, fréquente en Afrique soudano-sahélienne, est une cardiomyopathie dilatée de cause inconnue. Parmi les facteurs de risque identifiés une carence alimentaire en sélénium est discutée. Le but de ce travail est de définir le sélénium plasmatique de patientes en insuffisance cardiaque par cardiomyopathie péripartum à Bamako (République du Mali) et de le comparer à celui de sahéliennes en bonne santé à statut obstétrical identique. Afin de préciser le statut en sélénium à Bamako (République du Mali) les auteurs ont dosé le sélénium plasmatique chez 28 Maliennes atteintes de cardiomyopathie dilatée péripartum. Elles ont été appariées à 28 Nigériennes en bonne santé, d’âge comparable et allaitantes, constituant le groupe témoins. Le critère d’appariement a été la parité des malades et des témoins (nombre identique ou proche d’accouchements). Le test de Wilcoxon (test non paramétrique) a été appliqué pour comparer les 2 groupes, une valeur de p < 0,05 étant significative. Le sélénium plasmatique des patientes de Bamako (65 ± 17 ng/ml) est significativement plus bas que celui des Nigériennes en bonne santé de Niamey (78 ± 17 ng/ml, p = 0,01). Conclusion. La sélénémie des malades avec cardiomyopathie dilatée péripartum à Bamako est plus basse que dans la population témoin appariée, en accord avec les faits constatés antérieurement à Niamey.

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Metal Ions

Trace metals in human retina during aging period

Metal Ions in Biology and Medicine (2004) 491-495

Sergeant C., Vesvres M.-H., S Pravikoff M., Devès G., Yefimova M., Jonet L., Valtink M., Courtois Y., Jeanny J.-C.

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pas de couverture

Production rates for cosmogenic krypton and argon isotopes in H Chondrites with known 36Cl – 36Ar ages

Antarctic Meteorite Research 17 (2004) 185-199

I. Leya, E. Gilabert, B. Lavielle, U. Wiechert, R. Wieler

We present physical model calculations for the production of cosmogenic Kr isotopes in stony meteorites and compare the model results with measured data for bulk samples of 12 H-chondrites which recently had been investigated for their 36Cl-36Ar cosmic-ray exposure ages and light noble gas production rates. The correlation between P(81Kr)P(83Kr) and P(78Kr)P(83Kr) modelled here is significantly different from the classical relation commonly used to derive 81Kr-Kr exposure ages. For both relations, the 81Kr ages scatter considerably around the respective 36Cl-36Ar ages, but the new relation on average yields a somewhat better agreement between 81Kr-Kr and 36Cl-^<36>Ar ages. The calculations combined with concentration measurements of the main target elements for the production of cosmogenic Kr (Rb, Sr, Y, Zr, and Nb) show that target element chemistry does hardly influence the isotopic composition of cosmogenic Kr in bulk chondrites. These calculations also confirm earlier conclusions that the isotopic systematics of cosmogenic Kr in lunar samples are applicable for chondrites too. We derived an average 38Ar production rate at average shielding (22Ne21Ne=1.11) of (0.0431±0.0035)×10-8 cm3 STP(g×Myr).


Year 2003

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Journal of Environmental Radioactivity

Technetium species induced in maize as measured by phosphorimager

Journal of Environmental Radioactivity, Volume 70, Issues 1-2, 2003, Pages 139-154 M. Simonoff, T. V. Khijniak, C. Sergeant, M. H. Vesvres, M. S. Pravikoff, E. Leclerc-Cessac, G. Echevarria, S. Denys

Leaves of plants have the ability to accumulate the long-lived fission product 99Tc. In the present work, an attempt was made to separate and characterize technetium species formed in maize grown on soil contaminated with TcVIIO4- solution. Data obtained from selective extraction, a Phosphorimager and liquid scintillation were employed.

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Nuclear Instruments and Methods in Physics Research B

Iron, transferrin and myelinogenesis

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 210, September 2003, Pages 349-353

C. Sergeant, M. H. Vesvres, G. Devès, B. Baron, F. Guillou

Transferrin (Tf), the iron binding protein of vertebrates serum, is known to be synthesized by oligodendrocytes (Ols) in the central nervous system. It has been postulated that Tf is involved in Ols maturation and myelinogenesis. This link is particularly important in the understanding of a severe human pathology: the multiple sclerosis, which remains without efficient treatment. We generated transgenic mice containing the complete human Tf gene and extensive regulatory sequences from the 50 and 30 untranslated regions that specifically overexpress Tf in Ols. Brain cytoarchitecture of the transgenic mice appears to be normal in all brain regions examined, total myelin content is increased by 30% and motor coordination is significantly improved when compared with non-transgenic littermates. Tf role in the central nervous system may be related to its affinity for metallic cations. Normal and transgenic mice were used for determination of trace metals (iron, copper and zinc) and minerals (potassium and calcium) concentration in cerebellum and corpus callosum. The freeze-dried samples were prepared to allow proton-induced X-ray emission and Rutherford backscattering spectrometry analyses with the nuclear microprobe in Bordeaux. Preliminary results were obtained and carbon distribution was revealed as a very good analysis to distinguish precisely the white matter region. A comparison of metallic and mineral elements contents in brain between normal and transgenic mice shows that iron, copper and zinc levels remained constant. This result provides evidence that effects of Tf overexpression in the brain do not solely relate to iron transport.

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Czechoslovak Journal of Physics

Microbial reduction of 99Tc (TcO4-) in the anaerobic alkaline conditions by Genus Holomonas bacteria

Czechoslovak Journal of Physics, 53, suppl A (2003) 113-117

Khijniak T., Simonoff M., Medvedeva-Lyalikova N., Sergeant C., Simonoff G.

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FEMS

Reduction of pertechnetate by haloalcaliphilic strains of Halomonas

FEMS Microbiology Ecology, 44 (1), 109-115, 2003

Khijniak T., Simonoff M., Medvedeva-Lyalikova N., Sergeant C.

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Year 2002

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Metal Ions

Technetium species induced in maize

Metal Ions in Biology and Medicine, vol VII, John Libbey Eurotext, Paris, 2002, 275-278

Sergeant C., Simonoff M., Khijniak T.

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Meteoritics & Planetary Science

Production of krypton and xenon isotopes in thick stony and iron targets isotropically irradiated with 1600 MeV protons

Meteoritics & Planetary Science 37,951-976 (2002)

E. Gilabert, B. Lavielle, R. Michel, I. Leya, S. Neumann, U. Herpers

Two spherical targets made of gabbro with a radius of 25 cm and of steel with a radius of 10 cm were irradiated isotropically with 600 MeV protons at the SATURNE synchrotron at Laboratoire National Satume (LNS)/CEN Saclay, in order to simulate the production of nuclides in meteorites induced by galactic cosmic-ray protons in space. These experiments supply depth-dependent production rate data for a wide range ofradioactive and stable isotopes in up to 28 target elements. In this paper, we report results for 78Kr, 80-86Kr isotopes in Rb, Sr, Y and Zr and for 124Xe, 126Xe, 128-132Xe, 134Xe, 136Xe isotopes in Ba and La. Krypton and xenon concentrations have been measured at different depths in the spheres by using conventional mass spectrometry. Based on Monte-Carlo techniques, theoretical production rates are calculated by folding depth-dependent spectra of primary and secondary protons and secondary neutrons with the excitation functions of the relevant nuclear reactions. The comparison of the model calculation results with experimental data in the thick target experiments performed at LNS and previously at CERN have allowed adjustments of the poorly known excitation functions ofneutron-induced reactions. Thus, for the two experiments at SATURNE, excellent agreement is obtained between experimental and calculated production rates for most Kr and Xe isotopes in all investigated target elements. Only Xe production in Ba in the gabbro is underestimated by the calculations by -25%. This work validates the approach of the thin-target model calculations ofcosmogenic nuclide production rates in the attempt ofmodeling the interaction of galactic cosmic-ray protons with stony and iron meteorites in space as well as with lunar samples.

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Year 2001

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Nuclear Instruments and Methods in Physics Research B

Iron and other elements (Cu, Zn, Ca) contents in retina of rats during development and hereditary retinal degeneration

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 181, Issues 1-4, July 2001, Pages 533-538

C. Sergeant, Y. Llabadora, G. Devès, M. H. Vesvres, M. Simonoff, M. Yefimova, Y. Courtois and J. C. Jeanny

The retina as well as other tissues needs iron to survive, but modifications in iron metabolism have also been suggested to contribute to cerebral neurodegenerative diseases. Our study was intended to investigate iron distribution in the retina of normal rats and Royal College of Surgeons (RCS) rats affected by hereditary degeneration of the photoreceptors at different developmental stages (35, 45 and 55 days after birth).

Iron (Fe) distribution was determined by proton induced X-ray emission (PIXE) microanalysis on retinal sections and compared to other tissues (cornea, liver, spleen) and to other elements (Cu, Zn, Ca). Elemental concentrations were determined in different retinal layers especially the photoreceptors, which are progressively altered and disappear in the RCS rats.

Iron is unevenly distributed throughout the rat retina. The highest concentration is observed in the choroid and the retinal pigmented epithelium and in the inner segments of photoreceptors. Iron content is lower in the outer segments but still significant. It increases during both the development and the disease at the level of the segments. This last localised iron increase can result in an overproduction of free radicals and be correlated with the photoreceptor cell loss. The distributions of other elements (Cu, Zn, Ca) revealed interesting temporal progressions.

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