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The incorporation of actinides in lanthanide phosphate matrices crystallizing in the monazite structure has been intensely investigated in the past decades due to the relevance of these monazites as potential ceramic host phases for the immobilization of specific high level radioactive waste (HLW) streams [1-3]. In recent years, understanding the incorporation behaviour of trivalent dopants in the LnPO4•xH2O rhabdophane structure has been given more attention [4,5]. Rhabdophane is the hydrated phosphate precursor in the synthesis of monazites through precipitation routes and a potential secondary mineral controlling actinide solubility in dissolution and re-precipitation reactions of monazite host-phases. Despite the large interest in lanthanide phosphates and the interaction of actinides with these solids, very little data [6-8] is available on the complexation of lanthanides and actinides with aqueous phosphates, even though these complexation reactions precede any aqueous synthesis of monazite ceramics and are expected to occur in natural waters as well as in the proximity of monazite-containing HLW repositories. In many cases, an independent spectroscopic validation of the stoichiometry of the proposed complexes, is also missing. Both from the perspective of aqueous rhabdophane synthesis, which is often carried out at elevated temperatures, and heat-generating HLW immobilization in monazites, the lanthanide and actinide complexation reactions with aqueous phosphates under ambient conditions should be complemented with data obtained at higher temperatures. In the present work, laser-induced luminescence spectroscopy was used to study the complexation of Cm(III) (1.15×10−8 to 1.15×10−7 M) as a function of total phosphate concentration (0 to 0.08 M) in the temperature regime 25-90 °C, using NaClO4 as a background electrolyte (I = 0.5 to 3.0 M). These studies have been conducted in the acidic pH-range (−log10 [H+] = 1.00, 2.52, 3.44, and 3.65) to avoid precipitation of solid Cm rhabdophane. For the first time, in addition to the presence of CmH2PO42+ already evidenced before [6,7], the formation of Cm(H2PO4)2+ was unambiguously established from the luminescence spectroscopic data collected at the various H+ concentrations previously mentioned [8]. The conditional complexation constants of both aqueous complexes were found to increase upon rising ionic strength and temperature. Extrapolation of the obtained complexation constants to infinite dilution at 25 °C was performed by applying the Specific Ion Interaction Theory (SIT) [9]. The obtained log β° values for CmH2PO42+ and Cm(H2PO4)2+ were 0.45 ± 0.04 and 0.08 ± 0.07 [8], respectively, for reactions 1 and 2 below: Cm3+ + H3PO4 ⇌ CmH2PO42+ + H+ (1) Cm3+ + 2 H3PO4 ⇌ Cm(H2PO4)2+ + 2 H+ (2) The ion interaction coefficients ε(CmH2PO42+;ClO4−) = 0.17 ± 0.04 and ε(Cm(H2PO4)2+;ClO4−) = −0.10 ± 0.06 were derived at 25 °C [8]. Temperature-dependent conditional complexation constants for the identified species were obtained from the recorded luminescence emission spectra. They were subsequently extrapolated to I =0 M, assuming that the ion interaction parameters obtained at 25 °C are not significantly impacted by the temperature increase from 25 °C to 90 °C [6]. Using the integrated van´t Hoff equation, both the molar enthalpy of reaction ΔrHm° and entropy of reaction ΔrSm° values were found to be positive for the two complexes, namely CmH2PO42+ and Cm(H2PO4)2+ [8]. Relativistic quantum chemical investigations revealed a monodentate binding of the H2PO4− ligand to the central Cm3+ ion to be the most stable configuration for both complexes. By combining ab initio calculations with a thorough analysis of the obtained luminescence spectroscopic data, both CmH2PO42+ and Cm(H2PO4)2+ complexes with an overall CN of 9 were shown to be stable in solution at 25 °C. However, a different temperature-dependent evolution of the coordination of the Cm3+ ion to hydration water molecules could be derived from the electronic structure of the Cm(III)-phosphate complexes. More specifically, an overall coordination number of 9 was retained for the CmH2PO42+ complex in the investigated temperature range (25 to 90 °C), while a coordination change from 9 to 8 was established for the Cm(H2PO4)2+ species with increasing temperature [8]. This change of coordination upon increasing temperature, which has not been investigated in detail in the past, might also be relevant in the complexation of other f-elements with inorganic and/or organic ligands and deserves further exploration. [1] R. C. Ewing, Proc. Natl. Acad. Sci. USA 96, 3432 (1999). [2] D. Bregiroux et al., J. Nucl. Mater. 366, 52 (2007). [3] N. Huittinen et al., J. Nucl. Mater. 486, 148 (2017). [4] E. Du Fou de Kerdaniel, J. Nucl. Mater. 362, 451 (2007). [5] N. Huittinen et al., Inorg. Chem. 57, 6252−6265 (2018). [6] H. Moll et al., Radiochim. Acta, 99, 775−782 (2011). [7] N. Jordan et al., Inorg. Chem. 57, 7015-7024 (2018). [8] N. Huittinen et al., Inorg. Chem. 60, 10656−10673 (2021). [9] I. Grenthe et al., Second update on the chemical thermodynamics of uranium, neptunium, plutonium, americium and technetium, OECD Nuclear Energy Agency Data Bank, Eds., OECD Publications, Paris, France, (2020).

International audience; Presentation du parametrage de champs de force pour les actinides(IV) dans l'eau pour la dynamique moleculaire classique.Methode de parametrage et premiers resultats d'hydratation.

International audience; The DARWIN2.3 package is dedicated to spent fuel characterization in general and to decay heat computations in particular, and benefits from a Verification, Validation and Uncertainty Quantification process (VVetUQ). The current experimental results available are insufficient to accurately assess the biases and uncertainties due to nuclear data for the decay heat for the fuel managements of the French reactor fleet. This is the reason why an uncertainty propagation method has been recently implemented within the CYRUS tool (a mockup for the DARWIN2.3 package), and later on within the DARWIN2.3 package in order to compute a priori uncertainty due to nuclear data variance/covariance matrices. The method implemented is the quadratic summation method, which allows in-depth analysis of the uncertainty through sensitivity and variance analysis. Nevertheless, this method relies on a fundamental hypothesis of linearity, which is not straightforward in the case of the decay heat. Moreover, due to the specificity of the DARWIN2.3 package, approximations have been made when dealing with cross-sections, such as the collapsing of the multigroup covariance matrices, and the neglecting of the Boltzmann/Bateman coupling when computing the sensitivity profiles. These three items have been studied in details. This paper shows some of the results that accredit the legitimacy of the linearity hypothesis and collapsing method, and provide some recommendations in dealing with the Boltzmann/Bateman coupling.

Radiotherapy and oncology 127(Supplement 1), OC-0416 (2018). doi:10.1016/S0167-8140(18)30726-6 special issue: "ESTRO 37, April 20-24, 2018, Barcelona, Spain", Published by Elsevier Science, Amsterdam [u.a.]

International audience; The decay heat is a crucial issue for in-core safety after reactor shutdown and back-end cycle. An accurate computation of its value is done at the CEA within the DARWIN2.3 package. The DARWIN2.3 package benefits from a Verification, Validation and Uncertainty Quantification (VVUQ) process. The VVUQ ensures that the parameters of interest computed with the DARWIN2.3 package have been validated over experimental measurements and that biases and uncertainties have been quantified for a particular domain. For the parameter decay heat, there are few integral experiments available to ensure the experimental validation over the whole range of parameters needed to cover the French reactor fleet (fissile content, burnup, fuel, cooling time). The experimental validation currently covers PWR UOX fuels for cooling times only between 45 minutes and 42 days, and between 13 and 23 years. Therefore the uncertainty quantification step is of paramount importance in order to increase the reliability and accuracy of decay heat calculations. This paper focuses on the strategy that could be used to answer this issue with the complement and the exploitation of the DARWIN2.3 experimental validation.

International audience; An accurate estimation of the decay heat associated with controlled bias and uncertainty is of paramount importance for the design and the operation of future and current reactors as well as for the back- end cycle. The DARWIN2.3 package, dedicated to the characterization of spent fuels from reactors, benefits from the Verification, Validation and Uncertainty Quantification process. The goal of this paper is to illustrate how to exploit the corpus of integral experimental values for the decay heat though the bias transposition method in order to improve the accuracy of the decay heat calculations for industrial PWR reactors. In particular, parametric studies are conducted on the decay heat time dependence and discharge burn-up.

International audience

International audience

Atorvastatin calcium (ATV) is one of the most frequently prescribed drugs worldwide. Among the adverse effects observed for this lipid-lowering agent, clinical cases of cutaneous adverse reactions have been reported and associated with photosensitivity disorders. Previous work dealing with ATV photochemistry has shown that exposure to natural sunlight in aqueous solution leads to photoproducts resulting from oxidation of the pyrrole ring and from cyclization to a phenanthrene derivative. Laser flash photolysis of ATV, at both 266 and 308 nm, led to a transient spectrum with two maxima at λ ) 360 and λ ) 580 nm (τ ) 41 μs), which was assigned to the primary intermediate of the stilbene-like photocyclization. On the basis of the absence of a triplet-triplet absorption, the role of the parent drug as singlet oxygen photosensitizer can be discarded. By contrast, a stable phenanthrene-like photoproduct would be a good candidate to play this role. Laser flash photolysis of this compound showed a triplet-triplet transient absorption at λmax ) 460 nm with a lifetime of 26 μs, which was efficiently quenched by oxygen (kq ) 3 ((0.2) × 109 M-1 s-1). Its potential to photosensitize formation of singlet oxygen was confirmed by spin trapping experiments, through conversion of TEMP to the stable free radical TEMPO. The photoreactivity of the phenanthrene-like photoproduct was investigated using Trp as a marker. The disappearance of the amino acid fluorescence (λmax ) 340 nm) after increasing irradiation times at 355 nm was taken as a measurement of photodynamic oxidation. To confirm the involvement of a type II mechanism, the same experiment was also performed in D2O; this resulted in a significant enhancement of the reaction rate. On the basis of the obtained photophysical and photochemical results, the phototoxicity of atorvastatin can be attributed to singlet oxygen formation with the phenanthrene-like photoproduct as a photosensitizer.

The interaction of the nonsteroidal anti-inflammatory drug flurbiprofen (FBP) with human serum albumin (HSA) hardly influences the fluorescence of the protein's single tryptophan (Trp). Therefore, in addition to fluorescence, heavy atom-induced room-temperature phosphorescence is used to study the stereoselective binding of FBP enantiomers and their methyl esters to HSA. Maximal HSA phosphorescence intensities were obtained at a KI concentration of 0.2 M. The quenching of the Trp phosphorescence by FBP is mainly dynamic and based on Dexter energy transfer. The Stern-Volmer plots based on the phosphorescence lifetimes indicate that (R)-FBP causes a stronger Trp quenching than (S)-FBP. For the methyl esters of FBP, the opposite is observed: (S)-(FBPMe) quenches more than (R)-FBPMe. The Stern-Volmer plots of (R)-FBP and (R)-FBPMe are similar although their high-affinity binding sites are different. The methylation of (S)-FBP causes a large change in its effect on the HSA phosphorescence lifetime. Furthermore, the quenching constants of 3.0 × 10

Laboratory models enabling to study in vivo human leukocyte functions have been developed. Most of the models consist of human immunocytes transferred to mice homozygous for the scid mutation. Mice with additional immunodeficient-prone genetic background or with immunodeficiency-induced conditioning have also been used. Human grafts mainly consisted of human immune cells in suspension injected intraperitoneally, or in pieces of human organs containing immunocytes implanted subcutaneously. Cells in suspension could be easily manipulated in vitro before transfer to the animal, but disseminated within the mouse body. In opposition, human cells mostly remained within implantation areas of animals given human organ pieces. This favorizes cell interactions and helps for cell recovery after their in vivo passage. Moreover, the diversity of antibodies in animals transplanted with human lymphoid organ pieces appeared broader than that of mice transferred with lymphocytes in suspension. Spontaneous recall antibody and autoantibody productions have been generally observed in animals transferred with cells from donors with such antibodies. In vivo boosting of recall antibody by antigen has been most successful, but such a manipulation inconstantly boosted autoantibodies. Primary human T and B cell responses were difficult to obtain in xenochimeric animals, and success has been generally obtained by optimizing human immune response parameters, such as antigen presentation.

National audience; Ce document présente une analyse systémique des activités agroalimentaires en France (consommation, restauration hors foyer, grande distribution, agrofourniture, IAA) suivie d'un panorama des principales filières agroalimentaires (céréales, légumes, boissons non alcoolisées, produits laitiers, produits carnés). Il souligne les mutations importantes observées dans les différents sous-systèmes et la place significative occupée par la France sur l'échiquier agroalimentaire mondial.