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Seedling emergence vigor, establishment success, and biomass yield stability of cover crop mixtures compared to pure stands
No full textInternational audienceContext: Cover cropping has the potential to enhance the sustainability of cropping systems across temperate regions. However, poor establishment of cover crops (CCs), often driven by unfavorable weather conditions, remain a major barrier to their adoption. Sowing CC mixtures may mitigate the risks of poor establishment compared to pure stands, thereby lowering spatio-temporal variability in biomass production, which is critical for consistent ecosystem service provision. Yet, it is unclear whether CCs establish more successfully in mixtures than in pure stands, and whether a better establishment results in greater biomass production that enhances ecosystem services. Objective: We aimed to: i) analyze seedling emergence dynamics, final emergence rates, and emergence vigor (i. e., speed of emergence) in CC mixtures vs. pure stands; ii) determine the relationship between seedling establishment success and final biomass production; and iii) evaluate the effect of CC mixtures vs. pure stands on soil cover, weed suppression, nitrogen (N) catch crop, and N green manure services. Methods: A 2-year field experiment (2020-2022) was conducted in Southwestern France, testing 11 pure stands and six two-species mixtures of brassicas, legumes, and grasses. CCs were sown in autumn and grown for eight months, with a fallow treatment as control. Data were analyzed using analysis of variance. Results: Significant intra-(p < 0.001) and inter-annual (p < 0.001) variability was observed in CC seedling emergence dynamics. Brassica CCs showed the highest emergence vigor (77 ± 21 • Cd), and their establishment success was positively correlated with final biomass yield (0.4 ± 0.2-8.6 ± 0.6 t.ha -1 ; r = 0.61, p < 0.001). In contrast, legumes, such as faba bean, showed the lowest emergence vigor (147 ± 52 • Cd), and their biomass yield (3.1 ± 0.1-6.8 ± 0.4 t.ha -1 ) depended mainly on post-establishment climatic conditions. Seedling emergence vigor and establishment success did not differ significantly between CC mixtures and pure stands. Single species CC yielded more variable biomass between years, mixtures produced more stable yields (2.1 ± 0.1-9.9 ± 0.3 t. ha -1 ). Soil cover was similar between CC pure stands (75.0 ± 0.0-100.0 ± 0.0 %) and mixtures (66.7 ± 5.3-100.0 ± 0.0 %), whereas poor establishment reduced soil cover (25.0 ± 7.9-50 ± 0.0 %). All CCs effectively suppressed weeds (up to 100 % reduction in biomass) and supplied N through scavenging and/or green manuring (up to 203 ± 18 kgN.ha -1 ) compared to fallow. Implications: In systems dominated by monocultures or short rotations under high-input management and climatic uncertainty, Brassicaceae-Fabaceae mixtures represent a promising option to ensure good establishment, stable biomass production, and delivery of key ecosystem services
Corrosion fatigue mechanisms of high-strength steel wires in the presence of various aggressive ions
No full textInternational audienceThis work focuses on the corrosion fatigue of high-strength steel wires with diameters of 200 μm. The fatigue load consists of a bending rotation with a stress amplitude between 1300 MPa and 700 MPa. Various solutions at pH 6 containing either sulfate, a mixture of citrate and either phosphate or hydroxyl are selected to evaluate the role of each ion or their combinations in accelerating the breakdown of the wires. For the higher stress amplitude applied, the lifetime is almost independent of the solution, showing mechanically controlled damage. For the lowest stress amplitude, the corrosion-fatigue limit significantly evolves depending on the solution. Sulfate leads to the shortest lifetimes, whereas experiments performed in deionized water show the longest lifetimes. A combination of citrate with either phosphate or hydroxyl leads to intermediate lifetime. The effect of each ion on the stability of the iron hydroxide oxide and the iron dissolution mechanisms is discussed. The results highlight the role of the chemical affinity of these ions with the iron surface and their consequences in corrosion fatigue crack generation
Lower interventricular septal thickness from computed tomography predicts the need for pacemaker implantation after TAVR
No full textInternational audienceBackground: Transcatheter aortic valve replacement (TAVR) is the standard treatment for severe aortic stenosis (AS) in select patients. While membranous septum length and pre-TAVR conduction disturbances are known predictors of permanent pacemaker implantation (PPI), the impact of muscular interventricular septal (IVS) thickness, assessed via pre-procedural computed tomography (CT), remains unclear.Objectives: The aim of the study was to evaluate the role of septal thickness with cardiac CT in predicting the need for PPI after TAVR.Methods: This retrospective cohort study analyzed patients undergoing TAVR between January 2019 and December 2022. IVS thickness was measured in end-systole at various levels below the membranous septum on pre-procedural CT scans. Multivariable logistic regression models assessed predictors of PPI, including IVS thickness.Results: Among the 338 patients (median age: 81 years; 42.6 % women), 20.1 % required PPI post-TAVR. Patients needing PPI had significantly lower IVS thickness 2 mm (3.9 ± 0.8 mm vs. 4.5 ± 1.3 mm, p < 0.001), 5 mm (5.9 ± 1.1 mm vs. 6.8 ± 1.8 mm, p < 0.001), and 10 mm (9.3 ± 1.1 mm vs. 10.6 ± 2.3 mm, p < 0.001) below the membranous septum. Multivariable analysis identified IVS thickness at 10 mm (HR: 0.73, 95 % CI: 0.56-0.96, p = 0.023), membranous septum length (HR: 0.79, 95 % CI: 0.67-0.94, p = 0.007), and right bundle branch block (HR: 7.70, 95 % CI: 3.70-15.90, p < 0.001) as independent predictors of PPI.Conclusions: IVS thickness on pre-procedural CT independently predicts PPI post-TAVR and improves risk stratification
Disentangling yield level and yield stability when comparing multifaceted agricultural production systems
No full textInternational audienceWhich type of agricultural production systems promotes the most stable yield is a matter of debate, especially when comparing conventional and organic agriculture. Whether statistical or agroecological, a relationship often exists between the level and stability of agricultural production. In comparative studies of agricultural system yields, Taylor's Power Law often applies (i.e., empirical law between mean and variance). Once this law tested, the issue is to identify the proportion of stability that is determined by the agriculture type tested rather than by the production level.OBJECTIVEIn this short communication, we seek to disentangle biophysical and statistical effects related to the comparison of yield stability along intensification gradients of agriculture.METHODSWe carried out a short literature review and established a theorical analysis.RESULTS AND CONCLUSIONSTradeoffs between yield level and stability can be explained by analyzing potential effects of limiting factors at different levels of fertilization and irrigation. However, the level of intensification of cropping practices is not the only factor to consider; it is also necessary to consider the pedoclimatic conditions, economic context, and biological regulations. In the short and medium terms, the appropriateness of the production situation (i.e. the combination of crops, management, soil and climate) and resource availability and dynamics is also crucial to account for when designing resilient agricultural systems. In the long term, natural capital must be conserved to ensure the level and stability of agricultural production.SIGNIFICANCEWe highlight that identifying how production situations influence yield level and stability requires detailed multiscale and multifactor approaches
Adaptive mechanisms in pancreatic islets counteract mitochondrial dysfunction in Barth syndrome
No full textInternational audienceAims/hypothesis: Barth syndrome is a mitochondrial disorder caused by Tafazzin (TAZ) mutations, which impair cardiolipin remodelling and contribute to systemic metabolic alterations. While islet dysfunction has been implicated in Barth syndrome, its underlying mechanisms remain unknown. We aimed to determine how Tafazzin (Taz) deficiency affects mouse pancreatic islet metabolism and hormone secretion, and whether systemic signals, such as circulating factors, modulate these effects in vivo. In vivo and in vitro models were used to separate direct islet effects from systemic influences of Taz deficiency.Methods: We used a mouse model of global Taz knockdown (Taz-KD) and combined in vivo and in vitro approaches to assess pancreatic islet metabolism, morphology and hormone secretion. Islet function was evaluated under basal and glucotoxic conditions. Transcriptomic profiling was performed to identify gene expression changes in isolated islets from Taz-KD mice and following in vitro Taz-KD. Additionally, we examined the role of the circulating factor fibroblast growth factor 21 (FGF-21) in modulating islet function.Results: Despite impaired cardiolipin remodelling, pancreatic islets from Taz-KD mice maintained insulin secretion, supported by compensatory mechanisms such as increased glucose uptake, expanded mitochondrial volume and increased metabolic parameters. In addition, alpha cell mass and glucagon secretion were significantly increased in Taz-KD islets. These islet-specific adaptations occurred alongside improved whole-body glucose tolerance, elevated circulating FGF-21 levels and enhanced glucose uptake in brown adipose tissue. In contrast, in vitro Taz-KD led to impaired islet function and reduced insulin secretion. Transcriptomic analysis revealed distinct gene expression patterns between in vivo and in vitro Taz-KD models. While in vivo upregulation of genes related to N-acetylglucosamine biosynthesis and O-GlcNAcylation were related to compensatory mechanisms, in vitro Taz-KD affected, among others, the MAPK pathway, contributing to islet dysfunction. Notably, islet incubation with FGF-21 was able to restore insulin secretion after in vitro Taz-KD.Conclusions/interpretation: Our findings demonstrate that while Taz and cardiolipin remodelling are essential for beta cell physiology, systemic and islet-specific compensatory mechanisms preserve insulin secretion in vivo in Taz-KD mice, alongside increased glucagon secretion. These adaptations probably contribute to the altered metabolic phenotype observed in Barth syndrome and highlight a potential role for hormones and circulating factors such as FGF-21 in maintaining islet function and glucose homeostasis
Recent improvements in the analysis and characterization of fiber/matrix interfaces in biocomposites (Chap. 8)
No full textInternational audienceThis chapter aims to illustrate the correlation in the effect of free surface energy modification of natural fibers on the mechanical behavior of bio-based composites. It has been proved that enhancing the wettability of flax fibers by liquid epoxy resin implies a lower porosity amount in composites. The main outcome of multiscale consideration is that even if elementary fibers and yarns are embrittled and interface properties at the microscale are lowered by a thermal or chemical surface energy modification, the mechanical behavior of composites manufactured by liquid composite molding can be improved. Some questions are still open on the methodology to optimize treatments, especially on the scale at which the treatment is applied (yarn or fabric). The extension of those considerations to biocomposites with thermoplastic matrices should be done in the upcoming years to manufacture sustainable and circular composites
Le grand recul démocratique : principaux enseignements du rapport V-Dem édition 2025
No full textNational audienceL’institut V-Dem a publié en mars dernier l’édition 2025 de son rapport annuel sur l’état de la démocratie dans le monde. Cette nouvelle livraison dresse un tableau particulièrement inquiétant : les données confirment le déclin démocratique entamé depuis plusieurs années et éclairent une nouvelle vague d’autocratisation qui ne semble plus épargner les démocraties occidentales
Prussian blue functionalized MIL-101(Cr)-SO3H for Cs+ ion capture for the management of contaminated water
No full textInternational audienceThis study investigates the property of Metal-Organic Frameworks (MOFs) grafted with Prussian blue analogs (PBA) for the efficient removal of Cs+ ions from aqueous solutions. MIL-101(Cr)-SO3H-PBA material was synthesized using a two-step process: hydrothermal reaction between monosodium 2-sulfoterephthalic acid (BDC-SO3Na) and chromium oxide (CrO3) to produce MIL-101(Cr)-SO3H, followed by grafting with CuK2[Fe(CN)6] (PBA). Both materials were characterized using XRD, IR, N2 sorption and Raman spectroscopy. The results confirmed the conservation of MOF porosity after functionalization and the successful incorporation of PBA. Batch adsorption experiments were conducted to evaluate Cs+ removal performance of the adsorbents. The study examined contact time (up to 1440 min), pH (2, 7 and 11), initial Cs+ concentration (from 9 ppb to 1800 ppm) and competing ions. The resistance of the porous solids under drastic conditions involving gamma radiation (from 0.5 MGy up to10 MGy) was also investigated.MIL-101(Cr)-SO3H-PBA exhibited a maximum Cs⁺ adsorption capacity of 242 mg.gMOF-1, compared to 161 mg.gMOF-1 for pristine MIL-101(Cr)-SO3H and showed high selectivity toward Cs+ in the presence of competing ions (Na+, K+, Mg2+, Ca2+, Sr2+). MI-101(Cr)-SO3H-PBA also demonstrates remarkable stability under radiation and alkaline conditions, maintaining 95% efficiency, whereas the performance of pristine MIL-101(Cr)-SO3H material decreased significantly (7.5-fold decrease).Cette étude examine les propriétés des structures métal-organiques (MOF) greffées avec des analogues du bleu de Prusse (PBA) pour l'élimination efficace des ions Cs+ des solutions aqueuses. Le matériau MIL-101(Cr)-SO3H-PBA a été synthétisé selon un procédé en deux étapes : réaction hydrothermale entre l'acide 2-sulfotéréphtalique monosodique (BDC-SO3Na) et l'oxyde de chrome (CrO3) pour produire du MIL-101(Cr)-SO3H, suivie d'un greffage avec du CuK2[Fe(CN)6] (PBA). Les deux matériaux ont été caractérisés par DRX, IR, sorption de N2 et spectroscopie Raman. Les résultats ont confirmé la conservation de la porosité des MOF après fonctionnalisation et l'incorporation réussie du PBA. Des expériences d'adsorption par lots ont été menées pour évaluer les performances d'élimination du Cs+ des adsorbants. L'étude a examiné le temps de contact (jusqu'à 1 440 min), le pH (2, 7 et 11), la concentration initiale en Cs+ (de 9 ppb à 1 800 ppm) et les ions concurrents. La résistance des solides poreux à des conditions extrêmes impliquant un rayonnement gamma (de 0,5 MGy à 10 MGy) a également été étudiée.Le MIL-101(Cr)-SO3H-PBA a montré une capacité d'adsorption maximale de Cs+ de 242 mg.gMOF-1, contre 161 mg.gMOF-1 pour le MIL-101(Cr)-SO3H, et a montré une forte sélectivité pour le Cs+ en présence d'ions concurrents (Na+, K+, Mg2+, Ca2+, Sr2+). Le MI-101(Cr)-SO3H-PBA présente également une stabilité remarquable dans des conditions de rayonnement et alcalines, maintenant une efficacité de 95 %, tandis que les performances du matériau MIL-101(Cr)-SO3H ont diminué de manière significative (diminution de 7,5 fois)