HAL Portal ESPCI (Ecole Supérieure de Physique et de Chimie Industrielles)
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Boosting effect of encapsulated polyoxometalates in the photocatalytic CO2 reduction by MOF-545
No full textInternational audienc
MOF-Paper Composite for the capture of VOCs From laboratory prototype to a robust product
No full textInternational audienceWe present a sustainable shaping method for adsorbent materials based on cellulose pulp (derived from softwood kraft fibers) and microfibrillated cellulose (MFC). This strategy enables the production of mechanically robust composites with an exceptionally highporous solid content—reaching up to 90%—and is applicable across various classes of adsorbents
Mechanistic Insights into the In Situ Restructuring of Coordinated Copper in Postmetalated MOFs for Photocatalysis
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Inhibiting the JAK-STAT3 pathway in nucleus accumbens astrocytes alleviates cocaine-induced motor hyperactivity
No full textInternational audienceCocaine use disorder is a significant global health issue, and despite its widespread impact, effective treatments are lacking. While research has largely focused on the underlying neuronal mechanisms, the role of astrocytes, key regulators of synaptic transmission and plasticity, remains underexplored. Using a multidisciplinary approach that combines immunohistochemistry, electron microscopy, 3D cell reconstruction, viral gene transfer, and behavioral assays, we investigated the early adaptive responses of astrocytes to repeated cocaine administration. We report that cocaine administration induces astrocyte reactivity in the nucleus accumbens, characterized by structural remodeling, reduced synaptic coverage, and upregulation of reactivity-associated markers, including STAT3. Furthermore, we demonstrated that the JAK/STAT3 signaling pathway plays a critical role in the pathological structural astrocytic responses and in the cocaine-induced motor behavior. Our findings highlight astrocytes as pivotal players in the initial neural adaptations underlying cocaine-induced behavior. These data may provide a basis for the development of novel therapeutic strategies targeting astrocytes to address the structural and functional disruptions associated with cocaine exposure
Bridging the Theoretical Gap in Randomized Smoothing
No full textInternational audienceRandomized smoothing has become a leading approach for certifying adversarial robustness in machine learning models. However, a persistent gap remains between theoretical certified robustness and empirical robustness accuracy. This paper introduces a new framework that bridges this gap by leveraging Lipschitz continuity for certification and proposing a novel, less conservative method for computing confidence intervals in randomized smoothing. Our approach tightens the bounds of certified robustness, offering a more accurate reflection of model robustness in practice. Through rigorous experimentation we show that our method improves the robust accuracy, compressing the gap between empirical findings and previous theoretical results. We argue that investigating local Lipschitz constants and designing adhoc confidence intervals can further enhance the performance of randomized smoothing. These results pave the way for a deeper understanding of the relationship between Lipschitz continuity and certified robustness
A microfluidic band-pass filter for flexible fiber separation
No full textThe control of particle trajectories in structured microfluidic environments has significantly advanced sorting technologies, most notably through deterministic lateral displacement (DLD). While previous work has largely targeted rigid, near-spherical particles, the sorting of flexible, anisotropic objects such as fibers remains largely unexplored. Here, we combine experiments and simulations to demonstrate how tilted pillar arrays enable efficient, length-based separation of flexible fibers. We discover that these arrays act as band-pass filters, selectively inducing lateral migration in fibers whose lengths are close to the array period. Fibers significantly shorter or longer exhibit minimal lateral deviation. This migration arises from the interplay of fluid-structure interactions between fibers and the complex flow and steric interactions with the pillars. Depending on their length, fibers exhibit distinct transport regimes: short fibers zigzag in between pillars following the flow, intermediate length fibers exhibit wrapping and jumping from one pillar to another, leading to lateral displacement, and long fibers deform extensively, following mixed zigzag-jump trajectories with minimal lateral migration. We identify the mechanical tension that develops in the fiber when wrapped around the pillars as the driving mechanism of cross-streamline transport. Leveraging this band-pass effect, we designed a highly efficient separation device to collect monodisperse fiber suspensions. Our findings not only expand the functional scope of DLD-like systems but also open new avenues for understanding transport of anisotropic objects in porous media
Green polymerisation of renewable lignin-derived vinyl ketone monomer to form UV-degradable polymers
No full textInternational audienceWe report the synthesis of a novel aromatic vinyl ketone monomer (BioPVK) from an abundant product of lignin depolymerisation, syringaldehyde. We demonstrate that BioPVK can be homopolymerised and copolymerised with styrene (St) in green solvents (ethyl lactate or water) to produce UV-degradable polymers. The homopolymers produced showed good thermal properties with high stability (up to 370 °C) and high glass transition temperatures (91 °C), similar to that of polystyrene. After irradiation with UV-light for only 30 minutes, substantial loss in molar mass was observed by size exclusion chromatography demonstrating the degradability of these polymers in mild conditions. Furthermore, MALDI-TOF analysis revealed that UV-degradation produced small molecule aromatic compounds. Copolymerisation of BioPVK with styrene was performed as both a solution polymerisation in ethyl lactate and as a conventional emulsion polymerisation in water. As expected, the solution copolymers degraded under UV-light irradiation. The aqueous emulsion copolymerisation of BioPVK and St produced high molar mass UV-degradable copolymers (Mw of 172 kDa) as a colloidally stable latex in 2h. These high molar mass copolymers degraded readily in dilute solutions when irradiated with UV-light, but were less susceptible to degradation when cast as a solid film. This work provides progress into lignin-derived, UV-degradable, polymers and copolymers, offering industrially relevant and environmentally conscious degradable alternatives to current commodity plastics
The origin of high adherence in PSA foam tapes
No full textInternational audienceWe investigate the exceptional adhesion performance of pressure-sensitive adhesive (PSA) foam tapes by linking microscale damage mechanisms to macroscopic peel behavior. Using instrumented peel tests, side-view imaging, and microscopy, we..
Tunable Poly(butylene oxide)-stat-polyglycidol Copolymers for Microfluidic Assisted Nanoprecipitation Nanoparticle Design
No full textThe self-assembly of amphiphilic copolymers into well-defined nanoparticles depends on the interplay between polymer composition, solvent exchange kinetics, and processing conditions. In this study, we explore the anionic ring-opening copolymerization of 1,2-epoxybutane and ethoxyethyl glycidyl ether (EEGE) followed by a deprotection step to synthesize poly(butylene oxide)-stat-polyglycidol (PBO-stat-PG) copolymers with tunable amphiphilicity. Reactivity ratio analysis confirmed the formation of a gradient microstructure, with preferential incorporation of EEGE in the early polymerization stages. The copolymers were subsequently processed via bulk and microfluidic-assisted nanoprecipitation, and their self-assembly behavior was systematically investigated. Bulk nanoprecipitation demonstrated that the hydrophilic/hydrophobic balance plays a critical role in controlling nanoparticle formation, stability, and size distribution. Copolymers with 85/15 and 80/20 (BO/G) ratios exhibited the most favorable properties, leading to small, stable, and uniform nanoparticles, whereas excessive G content (≥70%) disrupted self-assembly, inducing irregular morphologies. To enhance nanoparticle homogeneity and minimize aggregation, hydrodynamic-flow-focusing (HFF) microfluidics with a fixed flow rate ratio and controlled mixing conditions were implemented. The highly reproducible microfluidic process enabled finer control over solvent exchange dynamics, leading to smaller and more monodisperse nanoparticles compared to bulk precipitation. The rapid solvent diffusion in the HFF system promoted fast nucleation, effectively reducing polydispersity and ensuring superior colloidal stability. This study establishes a direct correlation between copolymer composition, nanoprecipitation methods, and nanoparticle characteristics, providing a scalable and reproducible strategy for the design of well-defined amphiphilic nanostructures with a controlled hydrophilic/hydrophobic ratio. The optimized PBO-stat-PG nanoparticles present promising potential for biomedical applications, particularly in drug delivery, where controlled self-assembly and tailored hydrophilicity are crucial for performance
DNA Condensation-Inspired Assembly of DNA Nanotubes into Reversible Superstructures: A Base Pairing-Orthogonal Way to Create Rings, Bundles, or Vast Networks
No full textInternational audienceBy offering exquisite programmability, sequencespecific DNA self-assembly is the foundation of structural DNA nanotechnology but necessitates custom-designed DNA strands. Finding assembly principles orthogonal to base pairing is thus desirable not only to organize DNA in a sequence-independent manner but also to bring additional levels of control over preformed DNA self-assembled structures. Here, we report that self-assembled DNA nanotubes, upon the addition of DNA-condensing multivalent cations, including the naturally occurring polyamines spermidine and spermine, spontaneously condense to form higher-order structures including well-defined micrometer-sized rings and 30 to 60 nm wide bundles, in which DNA strands are parallelly packed with an interspacing ranging from 2.5 to 3 nm. In the semidilute regime, a new organization into vast tridimensional networks is observed for a specific range of charge ratios, prior to the formation of highly clustered bundles. We demonstrate that the process is electrostatically driven, conferring a ubiquitous character to this assembly principle. We report in particular a pivotal role of the counterion valency (the higher it is, the lower the charge ratio required), emphasizing the role of DNA neutralization through the entropically driven exchange between DNA counterions and the condensing agents. We also show an important role of DNA concentration for controlling the individual or interconnected nature of the formed structures as well as favoring the nanotube assembly. We finally devise methods for additional control, such as superstructure disassembly upon monovalent ion addition or photocontrol using a photosensitive DNA-condensing agent