CEA Marcoule

In France, alluvial aquifers provide 45% of the freshwater used for drinking, agriculture, and industry (Maréchal and Rouillard, 2020). These aquifers are often hydraulically connected to rivers and are particularly vulnerable due to their proximity to the surface. This proximity makes them sensitive to anthropogenic pressures both quantitatively and qualitatively. The current study aims to better understand groundwater-surface water interactions in an anthropized alluvial aquifer in the lower Rhône Valley. This goal will be achieved using multivariate statistical methods on hydrogeochemical and stable water isotope data. Two datasets were analyzed. One dataset contained inert tracers (Cl−, Br−, δ2H and δ18O) and included 667 water samples (40 rainwater, 110 surface water and 517 groundwater). The other dataset contained major and minor ions (Ca2+, Mg2+, K+, Na+, Cl−, SO42-, alkalinity, NO3−, Br− and U(VI)) and stable water isotopes (δ2H and δ18O) data., and included 374 water samples (37 surface water and 337 groundwater). First, a hierarchical cluster analysis (HCA) was applied to both datasets to better understand groundwater recharge and the geochemical processes that control groundwater chemistry in the study area. We used the recently developed t-distributed stochastic neighbor embedding (t-SNE) (Van Der Maaten and Hinton, 2008) method and principal component analysis (PCA) to assist with the cluster analysis and visualization. When HCA, PCA, and t-SNE were applied to inert tracers dataset, the results first revealed the distribution of groundwater on the study site between two recharge sources: the Rhône River and rainfall. Water samples collected along the Rhône River boundary are characterized by highly depleted δ2H and δ18O signatures, indicating the significant influence (up to 80%) of the Rhône on the recharge of the alluvial aquifer in this area. In contrast, groundwater samples collected in the northern and northwestern parts of the site showed highly enriched δ2H and δ18O signatures, similar to those of rainfall indicating dominant recharge from local precipitation. Others water samples are characterized by intermediate δ2H and δ18O signatures, falling between the signatures of rainfall and the Rhône River, indicating mixed recharge. These water samples are predominantly distributed in the southern part of the site. Second, the results revealed the response of the alluvial groundwater to exceptional climatic events. In 2022, particular isotopic signatures with higher deuterium excess and high chloride concentrations were observed in rainwater and the Rhône River, which are reflected in groundwater. This suggests an influence of continental air masses originating from the Sahara Desert (Xu-Yang et al., 2025). When HCA, PCA, and t-SNE were applied to the second dataset containing hydrogeochemical and stable water isotope data, the results identified water samples with high uranium and chloride concentrations, likely due to historical pollution. This study shows that t-SNE is a promising tool for assessing groundwater-surface water interactions in an alluvial aquifer when used to assist in cluster analysis. Compared with PCA, t-SNE can better identify hidden information and perform much better with complex, nonlinear hydrogeochemical, and stable water isotope data. ReferencesMaréchal and Rouillard, 2020.https://doi.org/10.1007/978-3-030-32766-8_2Van Der Maaten and Hinton, 2008.Res.9,2579–2625.Xu-Yang, et al., 2025.https://doi.org/10.1126/sciadv.adr9192

Lanthanide‐binding tag (LBT) optimized for protein labeling was engineered into calmodulin by inserting a variant sequence (W 7 Y 8 → Y 7 I 8 ) at Site 1 of the N‐terminal domain while inactivating Site 2, and the resulting CaMLBT was examined for its Ln‐binding properties. CaMLBT forms 1:1 complexes with all lanthanides. Fluorescence spectroscopy and CE‐ICP‐MS revealed dissociation constants ranging from sub‐nanomolar for La (Kd = 437 ± 259 pM) to the low picomolar range for Tb–Lu, reaching Kd = 1.1 ± 0.4 pM for Lu at pH 6. This corresponds to a ∼1000‐fold affinity increase over the original LBT, approaching the stabilities of lanmodulins. In contrast to lanmodulins, however, Ln–CaMLBT complex stability increases with decreasing Ln(III) ionic radius, consistent with trends reported for LBT. ATR‐FTIR spectroscopy indicates that the enhanced stability arises from changes in coordination number and ligand properties: Glu 9 would evolve from tight bidentate (La to Pr) to more asymmetric or weaker (Yb and Lu) coordination, while Asp 3 and Asp 5 evolve from pseudo‐bridging to strong monodentate ligands. Notably, no evidence for water ligation was found for early lanthanides. CaMLBT emerges as a highly stable and versatile scaffold to investigate structural factors underlying lanthanide selectivity and complex stability.

Membrane reactors applied to methanol synthesis from CO 2 aim to alleviate low reaction conversions by shifting the thermodynamic equilibrium through in-situ water removal. The comparison between membrane reactors and conventional fixed-bed reactors has been previously studied in the literature at the process level. In fact, in the literature, membrane and conventional fixed-bed reactors have been so far compared under identical operating conditions at the process scale. However, studies at the reactor scale have identified that these types of reactors might have different optimal operating conditions. Therefore, potential biases in previous process simulation studies are investigated in the present article through process optimization using an energy cost criterion. This study uses design-free pseudo-homogeneous isothermal and isobaric plug-flow reactor models allowing the use of simplified and broad optimization variables. As a result, the optimal operating conditions for the membrane reactor process were found to depend significantly on the reactor’s GHSV and the membrane’s selectivity, and these conditions can differ greatly from those of a conventional fixed-bed reactor process. As such, comparing the two reactor types under the same operating conditions at the process level can lead to a bias favoring one reactor type depending on the chosen conditions. This study also explores the advantages of using compressed sweep gas and compares the performance of the two reactor types when varying levels of energy penalties are applied to high recycle ratios through the purge rate. • Identical conditions may bias fair comparison of membrane and conventional reactors. • Biases range from minor to large, depending on membrane selectivity and recycle rate. • GHSV, selectivity, and purge rate are key to determine optimal operating conditions.