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Submicron-sized anhydrous crystalline silicates and their relation to amorphous silicate in the matrix of Acfer 094
No full textInternational audienceThe study of pristine chondrites provides insight into nebular processes that occurred prior to the accretion of small-sized parent bodies. The interchondrule matrix of the primitive chondrite Acfer 094 is characterized by the presence of submicron-sized anhydrous crystalline aggregates embedded in a silicate groundmass that is mostly amorphous. Transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDXS) were employed to investigate the matrix of Acfer 094 and its components.The amorphous silicate groundmass is homogeneous in composition and exhibits a Mg depletion relative to the solar value. It embeds Fe-Ni nanosulfides, whose typical size is a few tens of nanometers. Nanometer-sized fibrous silicates are rare in the groundmass indicating a low degree of aqueous alteration. Submicron-sized Mg-rich crystalline silicates (olivine and pyroxene) occur either as isolated grains or as aggregates. These submicron-sized crystalline silicates occupy around 25 % of the matrix volume. The isolated grains display a wide range of shapes, from rounded to irregularly angular, and could have originated from the fragmentation of type I chondrules or from nebular condensation. The aggregates exhibit variable morphologies and grain sizes (typically a few tens of nm). They are chemically equilibrated, and likely formed by solid-state thermal annealing of amorphous precursors.The Acfer 094 matrix contains a range of components that have undergone varying degrees of thermal modification. A significant proportion of a precursor material (i.e. nebular dust) resembling matrix is likely to have undergone one or more brief and intense thermal events, potentially associated with the process of chondrule formation. These events resulted in the formation of magnesium-rich anhydrous silicates (forsterite and enstatite) at high temperatures that were embedded in the matrix of Acfer 094 as isolated grains and crystalline aggregates
Design and evaluation of novel triazole derivatives as potential anti-gout inhibitors: a comprehensive molecular modeling study
No full textInternational audienceIntroduction: Gout is the most common inflammatory arthritis, characterized by hyperuricemia, tophus formation, joint disease, and kidney stones. Uric acid, the final byproduct of purine catabolism, is eliminated via the kidneys and digestive system. Xanthine oxidase (XO) catalyzes the conversion of hypoxanthine and xanthine into uric acid, making XO inhibitors crucial for treating hyperuricemia and gout. Currently, three XO inhibitors are clinically used, showing significant efficacy. A molecular modeling study on triazole derivatives aims to identify novel XO inhibitors using 3D-QSAR, molecular docking, MD simulations, ADMET analysis, and DFT calculations. These computational approaches facilitate drug discovery while reducing research costs.Methods: Our work focuses on a series of synthesized anti-xanthine oxidase inhibitors, aiming to develop new inhibitors. A computational study was carried out to identify the xanthine oxidase inhibitory structural features of a series of triazole inhibitors using computational method.Results: A model based on CoMFA and CoMSIA/SEA has been built to predict new triazole derivatives.Discussion: The optimal model established from CoMFA and CoMSIA/SEA was successfully evaluated for its predictive capability. Visualization of the contour maps of both models showed that modifying the substituents plays a key role in enhancing the biological activity of anti-gout inhibitors. Molecular docking results for complexes N°8-3NVY and N°22-3NVY showed scores of −7.22 kcal/mol and −8.36 kcal/mol, respectively, indicating substantial affinity for the enzyme. Complex N°8-3NVY forms two hydrogen bonds with SER 69 and ASN 71, three alkyl bonds with ALA 70, LEU 74, and ALA 75, and one Pi-Pi T-shaped bond with PHE 68. Complex N°22-3NVY forms three hydrogen bonds with HIS 99, ARG 29, and ILE 91, and one halogen bond with LEU 128 at 3.60 Å. A MD study revealed that the N°22-3NVY complex remained highly stable throughout the simulation. Therefore, we proposed six new molecules, their anti-gout inhibitory activities were predicted using two models, and they were evaluated for Lipinski's rule, and ADMET properties. The results show that both Pred 4 and Pred 5 have better pharmacokinetic properties than the height potent molecule in the studied series, making these two compounds valuable candidates for new anti-gout drugs. Subsequently, using DFT study to evaluate the chemical reactivity properties of these two proposed compounds, the energy gap results revealed that both molecules exhibit moderate chemical stability and reactivity
A comprehensive theoretical study of structural and electronic features in LaOInS 2 polymorphs for photocatalytic applications
No full textInternational audiencePhotocatalysis has emerged as an essential strategy for sustainable solar fuel production, driving the development of efficient materials with advanced properties, including those based on mixed anion systems. In this study, we thoroughly investigate the electronic and optical properties of LaOInS2 polymorphs, including a-LaOInS2, layered LaOInS2, and hypothetical structures predicted by USPEX. All polymorphs demonstrate mechanical and dynamic stability. Using hybrid exchange-correlation functionals within first-principles density functional theory, we accurately simulate their electronic structures and optical properties. Our calculations reveal that the heteroleptic oxide-sulfide environment in a-LaOInS2 and the hypothetical structures lead to a higher electronic band gap compared to the layered LaOInS2. The projected density of states analysis highlights the significant impact of the mixed anionic environment of the In-S-O octahedron on the band gap, charge distribution, and chemical bonding, subsequently influencing the optoelectronic properties. Additionally, we find that these LaOInS2 polymorphs could serve as efficient photocatalysts for water splitting. Notably, the optical properties indicate a significantly higher and anisotropic visible light absorption in a-LaOInS2 as compared to the hypothetical USPEX predicted LaOInS2 polymorphs. Our findings suggest that oxygen vacancies can be exploited to tune the band gap and optical properties in a-LaOInS2. This study underscores the critical role of the mixed anionic environment in determining the physical and chemical properties of LaOInS2 polymorphs
Plastics used in agriculture and for food: uses, properties and impacts. Condensed report of the collective scientific assessment
No full textPatagonia, Norsys: Qui est légitime pour parler au nom de la nature dans les entreprises ?
No full textInternational audienc
Navigating the legal environment of AI (part 1)
No full textIESEG Insights, https://insights.ieseg.fr/en/resource-center/navigating-legal-environment-artificial-intelligence-ai
Mobilization and deposition of plastic along an estuarine bank during tidal cycles
No full textInternational audienceEstuaries represent a transitional environment between continental and marine areas. Limited studies have evaluated how these complex systems contribute to plastic pollution dynamics at this interface. Here, an in situ experimental study was conducted in the Slack estuary, a small macrotidal estuarine system in northern France, to investigate the mobilization and deposition of plastic debris on an estuarine bank at a daily basis during six complete tidal cycles. To achieve this, plastics (macro, meso and microplastics with size ≥3 mm) of different composition and shape were manually deposited along an estuary bank on three different substrates: vegetation, gravel, and sand. The experimental design aimed to explore the complexity of the mobilization and deposition of plastic debris with regard to hydro-meteorological factors, types of substrates, size and shape of plastics. Results showed that tidal cycles played a significant role in plastic mobilization and deposition on the estuary bank. However, the nature of the substrate directly impacted the mobilization and deposition of plastics and the effect of wind may be particularly important for the deposition of allochthonous plastics. Most plastics (around 94 %, 37.9 ± 1.5 plastics/m2) were found to be mobilized after a complete tidal cycle while an average of 3.33 ± 1.8 plastics/m2 was deposited during the same period. Results suggested that in small macrotidal estuaries, the daily net retention is very limited since most plastics were mobilized after a tidal cycle. However, in vegetated substrate, the daily net retention can be 2 to 3 times higher than in other types of substrates (gravel and sand) highlighting the potential of dense vegetation to serve as a retention area for plastic waste
L’engagement en pleine conscience : une étude des effets de la pleine conscience sur l'engagement organisationnel affectif
No full textNational audienc
Validity and Reproducibility of the Six-Minute Stepper Test in Cardiac Patients
No full textInternational audienceThe Six-Minute Walk Test (6MWT) traditionally assesses exercise capacity in cardiac patients but requires a large space. The Six-Minute Stepper Test (6MST) has been validated as an alternative in various populations. This study evaluates the reproducibility, sensitivity, and validity of the 6MST in 60 cardiac patients (15 women, 45 men, 58 ± 11.2 years). Participants underwent cardiopulmonary exercise tests (CPET), two 6MSTs, and one 6MWT at the start and end of cardiac rehabilitation (CR). Performance in the 6MST improved significantly after CR (343 ± 89.0 vs. 451 ± 105.6 steps, p < 0.0001). The 6MST showed moderate correlation with the 6MWT and CPET (r = 0.54, p < 0.0001). Dyspnoea and leg fatigue were higher in the 6MST than in the 6MWT (p < 0.0001). Conclusion: The 6MST is a safe, valid, sensitive, and reproducible tool for evaluating exercise capacity in cardiac patients, comparable to the 6MWT
An Upgraded FOS/TAC Titration Model Integrating Phosphate Effects for Accurate Assessments of Volatile Fatty Acids and Alkalinity in Anaerobic Media
No full textInternational audienceThe accurate determination of volatile fatty acids (VFAs) and total alkalinity (TAC, mostly carried by bicarbonate ions) is critical for operating anaerobic digesters. The FOS/TAC titration method developed by Nordmann is widely used due to its simplicity and affordability. This method has known limitations in dosing VFAs and TAC, since the presence of one interferes with the determination of the other, especially at higher VFA or bicarbonate concentrations. This study builds upon our prior research in 2021 by integrating the influence of phosphate (H2PO4−/HPO42−) into numerical models correcting FOS/TAC titration results. A Scilab-based program was used to assess the impact of phosphate on titration results, revealing significant biases at lower concentrations. A revised multivariate regression formula was developed, incorporating phosphate effects, and demonstrating superior accuracy. The mean absolute percentage errors (MAPE) for TAC and VFA estimation were reduced to less than 0.3%. The model maintains compatibility with standard Nordmann’s titration protocols and equipment while significantly improving reliability. These findings highlight the necessity of considering phosphate interference in FOS/TAC titration, particularly in AD systems with variable buffering conditions. The proposed correction model enhances process monitoring and control, providing a more robust tool for both research and industrial practice in anaerobic digestion