Discrete numerical analysis of cohesive granular flow in a thin rotating drum: Flow regimes and cohesion estimation

International audienceIn this study, we investigate the rheological behavior of cohesive granular flows within a rotating drum geometry using discrete element method (DEM) simulations. By systematically varying particle size, cohesion, and stiffness, we identify the emergence of distinct flow regimes-consistent with prior experimental observations. While the transitions between these regimes are primarily governed by cohesion, particle stiffness is also shown to significantly influence flow dynamics.To interpret the numerical results, we employ a dimensional analysis rooted in the physics of adhesive particle collisions. This analysis provides a conceptual framework for the remainder of the paper, which explores how "upscaled" discrete simulations can replicate experimental findings and help infer interparticle contact properties such as the adhesive surface energy. Notably, we use it to examine rotating drum experiments involving a unique class of granular materials, ice powders, which holds particular relevance in planetary science applications, and which flowability was shown to be strongly temperature-dependent.</div

Tuberculosis detection on chest X-rays using two-dimensional multiscale symbolic dynamic entropy

Available online 14 July 2025International audienceSeveral radiological patterns associated with pulmonary tuberculosis (TB) have been identified on chest X-rays (CXR) used for screening purposes. As a result, several automatic computational tools have emerged for this purpose. We propose a new algorithm, two-dimensional multiscale symbolic dynamic entropy (MSDE), to develop a computational tool sensitive to these subtle patterns variations and noise robustness for evaluating CXR images from healthy and TB-diagnosed individuals. The one-dimensional SDE algorithm was previously shown to be more efficient in detecting amplitude variations and in computational calculations (compared to other entropy algorithms). Additionally, we also extracted first-order statistical parameters like standard deviation (SD), and mean of positive pixels (MPP), among others. These MSDE and first-order texture features were used to detect TB in each lung individually. The MSDE was validated using a synthetic dataset and optimized for the best set of parameters. We verified that, for both lungs, the MSDE values were significantly different between healthy and TB CXR images (), and the effect size was d 0.23. From the first-order parameters, only the mean, SD, entropy, and MPP were statistically different between both groups for the left lung (; d 0.22). For the right lung, all first-order features significantly differentiated TB patients (; d 0.28). Finally, we show that a multi-layer perceptron obtained 86.4 and 85.2% accuracy in detecting TB in the left and right lungs, respectively. The highest sensitivity values achieved in this study were 71.4% and 81.8% for the left and right lungs, respectively

Un partage d’expérience autour de la pratique de l’interdisciplinarité sur les feux : le projet EcoSoFI (2022-2024)

International audienceLes collaborations inter/transdisciplinaires autour de la compréhension des feux et de leur gestion sont plébiscitées, mais leur mise en œuvre ne va pas pour autant de soi. A partir du partage d’expériences de plusieurs scientifiques et gestionnaires, le présent article restitue la démarche que nous avons adoptée pour comprendre ces difficultés ; et tire quelques constats et propositions. Onconstate notamment la dominance des sciences biophysiques et le poids de la modélisation dans les interfaces entre recherche et gestion. Au sein des SHS, on observe également des partitions entre disciplines et sous-disciplines, ainsi qu’une « interdisciplinarité inachevée » dans l’analyse des changements de régimes de feux. La spécialisation disciplinaire a conduit à une autonomisation du questionnement et des méthodes, qui ne sont plus explicitées ni interrogées au regard des autres approches et du terrain. Nos propositions consistent à remettre en question les catégories implicites concernant les pratiques et les savoirs liés aux feux et à définir des protocoles de recherche permettant des problématisations communes à partir d’études de cas localisées et « concrètes »

Bioelectricity Harvesting via a Microbial Fuel Cell with Sulfonated Hypercrosslinked Polyphenols and Polyethersulfone Composite Proton-Conducting Membrane

International audienceIn this research, a novel polyelectrolyte composite membrane was developed by combining sulfonated polyethersulfone (sPES) and sulfonated hypercrosslinked polymers (sHCP) to enhance microbial fuel cell (MFC) performances. Various characterization strategies confirmed that the incorporation of sulfonic groups boosted proton conductivity and hydrophilicity, with sHCP further enhancing these properties. The sulfonation degrees were measured at 51.80 % for sPES, 48.54 % for sHCP, and 66.05 % for the sPES/sHCP0.8 composite. Key physical properties included a water uptake (WU) of 54.30 %, surface roughness (SR) values of 21.53 % and 33.25 %, and ion-exchange capacity (IEC) measurements of 1.97 and 2.38 meq/g for sPES and sPES/sHCP0.8, respectively. Proton conductivity (PC) reached 4.03 mS/cm for sPES and 5.53 mS/cm for sPES/sHCP0.8. In contrast, Nafion-117 exhibited a high O 2 diffusion coefficient of 1.44 cm 2 /s and a transport rate coefficient of 0.123 cm/s, while sPES/sHCP0.8 demonstrated minimal O 2 migration, with diffusion coefficients of 1.73 × 10 -2 cm 2 /s and a transport rate of 2.45 × 10 -3 cm/s. The sPES/sHCP0.8 membrane displayed superior tensile stress, elastic modulus, and strain at break compared to PES, sPES, and Nafion-117, measuring 73.48 MPa, 7.49 %, and 15.80 MPa, respectively. Findings indicated that membrane selection is crucial for COD removal efficiency and energy generation. The MFC with the sPES/sHCP0.8 polyelectrolyte achieved a coulombic efficiency of 0.8 %, a COD reduction of 84.37 %, and an energy density of 80.96 mW/m 2 , outperforming Nafion-117 (28.56 mW/m 2 ) and sPES20 (28.56 mW/m 2 ) in batch mode over five days. Additionally, bioelectricity was harvested at 32.38 Wh/m 3 (NERv) and 10.9 kW/kg COD (NERs). However, the highest COD removal of 96.54 % was attained with MFCs using sPES20/sHCP160-0.8 and sPES20/sHCP180-0.4. The maximum I max was 690 mA/m 2 (1150 mA/ m 3 ) with sPES20/sHCP180-0.6, which also achieved the highest CE of 0.88 %. This study demonstrates that integrating sHCP enhances membrane properties while maintaining thermal and mechanical stability, significantly improving MFC performance

Territoria Naturalia. Aménager sans altérer, entre partage et réserve

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Orientation of nitration in bay-region of benzothioxanthene imide: A streamlined pathway to N- and S-annulated derivatives

International audienceN-annulation has recently emerged as a powerful approach for modulating the optoelectronic properties of benzothioxanthene imide (BTI) derivatives, enabling their application in areas ranging from light-emitting devices to photodynamic therapy. In this study, we report an optimized synthetic strategy that reduces the original seven-step process for N-annulated BTIs to just four steps, achieving a similar to 40 % improvement in efficiency. Additionally, we introduce a novel S-annulated BTI derivative, extending the scope of heteroatom-involving ring fusion. Comparative analysis between N- and S-annulated compounds reveals the pronounced influence of a single-atom modification on the pi-conjugated system. These findings demonstrate the utility of annulation as a chemically accessible and versatile tool for fine-tuning molecular architectures with tailored photophysical properties

Structural analysis and sequential resolution for estimation of guaranteed horizons in Partially Observable Petri Nets

International audienceIn Partially Observable Petri Nets, a necessary parameter is the guaranteed horizon, which allows the modelling of the estimation problem with the counter form and can be exploited in estimation for any linear criterion: a problem is the online estimation of the guaranteed horizon, which is a maximum sequence length relevant to a sliding horizon or a receding horizon starting from the initial marking. Considering large scale Petri nets, the objective of this paper is to facilitate the resolution by the construction of a triangular form guiding a sequential resolution of the problem based on substructures. This study shows that the classical Dulmage-Mendelsohn decomposition can be applied to a class of Petri nets where the unobservable induced Petri Net is mainly Forward Conflict Free. An extension of this result to any Petri net based on the building of an associated Petri net is made.</div

Effects of polysaccharide-based edible coatings on the shelf life of fresh-cut carrots with different pigmentations

International audiencePromoting the consumption of purple carrots, particularly in ready-to-eat products, is justified due to their peculiar composition and health benefits for consumers. However, there is limited literature on the shelf life of ready-to-eat purple carrots and the potential role of edible coatings in mitigating their quality decay. This study examined the postharvest behavior of sliced carrots 'Dordogne' (orange) and 'Purple Sun' (purple), both uncoated and coated with chitosan (CH) or locust bean gum (LBG), stored for 0 (S 0 ), 4 (S 4 ), and 8 (S 8 ) days at 4.0 • C. 'Purple Sun' proved a high fresh weight loss (up to 7.57 g 100 g -1 FW) and respiration metabolism. Compared to controls, CH reduced total color difference in 'Dordogne' (-70 %) but increased it in 'Purple Sun' (+68 %) due to the occurrence of tissue browning. Compared to uncoated controls, at the end of storage, total phenolic and ascorbic acid contents were lower in CH-coated 'Purple Sun' (-14 % and -20 %, respectively), while CH preserved total carotenoid content in 'Dordogne' (up to 1000 mg kg -1 DW). Moreover, compared to controls, LBG promoted Pseudomonas spp. (+23 % and +22 % in 'Dordogne' and 'Purple Sun', respectively) and yeasts and molds (+26 % and +24 %, respectively). Overall, these results indicate that issues of ready-to-eat carrots are significantly affected by carrot type, with the gas-barrier effect (in the case of CH for 'Purple Sun') and the antimicrobial properties of LBG (for both cultivars) seeming the most critical aspects to enhance the shelf life of the tested carrots

One-Step Synthesis of Poly(2-alkyl-2-oxazoline)-Coated Gold Nanospheres: A Greener Approach for Biomedical Uses

International audienceThe biological application of gold nanospheres (AuNSs) is often constrained by their stability and cytotoxicity. We present a greener synthetic approach that gives a simple and more environmentally friendly route to synthesizing AuNSs for biomedical applications. In this study, we detail a novel one-step, green synthesis of poly(2-alkyl-2-oxazoline) (POx)-coated AuNSs, which eliminates the need for additional reducing and stabilizing agents. The impact of the polymer structure on the nanoparticle formulation kinetics and nanoparticle characteristics is thoroughly investigated, revealing that the terminal functional group and the alkyl side chain significantly influence the reduction and stabilization process of AuNSs. Finally, POx-coated AuNSs were tested in vitro against F98 glioblastoma cells and proved to be usable without significant toxicity up to 75 μM. Herein, the outlined rapid and efficient method of the preparation of POx-coated AuNSs serves as a foundation for advancing the development of complex AuNSs tailored for biomedical applications.</div

Elucidation of Switching Mechanisms in Memristive Junctions Integrating a Iron(II)‐Ter Pyridine Diazoted Complex

International audienceAn original way of elaborating vertical metal/molecules/metal memristive junctions through diazonium electrografting of the organic layer and inkjet‐printed top electrodes is reported here. The molecule of interest is a Fe II coordination complex with ter‐pyridine ligands, having a diazonium anchoring group. The resulting junction exhibits a memristive behavior characterized by a high ON/OFF ratio and plasticity property. Through the application of advanced techniques such as UV–vis and Raman time‐resolved spectroelectrochemistry, the study demonstrates the significant role of switchable azo bonds derived from diazo electrografting in memristive behavior