HAL Portal ESPCI (Ecole Supérieure de Physique et de Chimie Industrielles)
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Novel MOF paper composites for the removal of airborne pollutants from the environment of cultural heritage artefacts
No full textInternational audienceThe quality of indoor air in Cultural Heritage (CH) institutions is a prime concern for the preservation of the artefacts in the collections. When stored in enclosures such as boxes and cabinets, or when exhibited in display cases or poorly ventilated rooms, a buildup of pollutants, in particular very volatile (VVOCs) and volatile organic compounds (VOCs), can occur and be detrimental to the objects. These airborne pollutants arise from the slow deterioration of the objects themselves as well as from the outgassing of storage, exhibition and cleaning products and materials (wood, plastics, varnishes, paints, cleaning products). Carboxylic acids are a category of airborne pollutants that are particularly harmful to cultural goods, while aldehydes might be hazardous to human health. Adsorbents are often used to trap these pollutants, and currently activated carbons and zeolites are the most common ones. Nonetheless they are not compound-selective, their efficiency and regeneration ability are limited and they can re-emit the pollutants. Metal-Organic Frameworks (MOFs) and, specifically, the benchmark mesoporous Fe(III) trimesate MOF denoted MIL-100(Fe), have been recently reported to selectively capture carboxylic acids, even in the presence of moisture. In this work, we studied three adsorbents, namely activated carbon, NaY zeolite and the MOF MIL-100(Fe), shaped as paper sheets, by mixing them with cellulose fibers and nanofibers. Their performance for the capture of various target substances notoriously emitted by CH artefacts, namely formic acid, acetic acid, acrylic acid, and furfural was compared. The tests were carried out in passive adsorption mode, in a purpose-made exposure laboratory bottle, in the presence of moisture and at pollutant concentrations of a few hundred ppm. The MOF paper composite showed better efficiency than the other two paper composites, being 15% to 30% more efficient than the activated carbon paper at target substance saturation level and reaching adsorption capacities between 200 and 300 (mgpollutant.g-1 adsorbent) under the experimental conditions. Moreover, only the MOF paper sheet did not release the pollutants. In a view of a practical application, the MIL-100(Fe) paper sheet was tested for the adsorption of acetic acid vapours emitted by cellulose acetate films, and confirmed the experimental results. This innovative solution could therefore be of use for air purification in heritage institutions to better protect airborne pollutant-sensitive cultural artefacts
Event-chain Monte Carlo and the true self-avoiding walk
No full text14 pages, 10 figuresInternational audienceWe study the large-scale dynamics of event-chain Monte Carlo (ECMC) algorithms in one dimension and their relation to the true self-avoiding walk. In particular, we study the influence of stress and different forms of interaction on the equilibration and sampling properties of algorithms that satisfy global balance but not local balance. We conclude that a broad class of interaction potentials, corresponding to different physical systems, display identical large-scale dynamics
Steady-state neuron-predominant LINE-1 encoded ORF1p protein and LINE-1 RNA increase with aging in the mouse and human brain
No full textReviewed Preprint published in e-Life https://elifesciences.org/reviewed-preprints/100687v1International audienceRecent studies have established a reciprocal causal link between aging and the activation of transposable elements, characterized in particular by a de-repression of LINE-1 retrotransposons. These LINE-1 elements represent 21% of the human genome, but only a minority of these sequences retain the coding potential essential for their mobility. LINE-1 encoded proteins can induce cell toxicity implicated in aging and neurodegenerative diseases. However, our knowledge of the expression and localization of LINE-1-encoded proteins in the central nervous system is limited. Using a novel approach combining atlas-based brain mapping with deep-learning algorithms on large-scale pyramidal brain images, we unveil a heterogeneous, neuron-predominant and widespread ORF1p expression throughout the murine brain at steady-state. In aged mice, ORF1p expression increases significantly which is corroborated in human post-mortem dopaminergic neurons by an increase in young LINE-1 elements including those with open reading frames. Mass spectrometry analysis of endogenous mouse ORF1p revealed novel, neuron-specific protein interactors. These findings contribute to a comprehensive description of the dynamics of LINE-1 and ORF1p expression in the brain at steady-state and in aging and provide insights on ORF1p protein interactions in the brain
Révéler le couplage neurovasculaire avec une haute résolution spatiale et temporelle dans la rétine humaine in-vivo
No full textInternational audienceNeurovascular coupling (NVC) regulates local blood flow in response to neuronal activity, yet its precise characterization at the capillary level has been hindered by the lack of a noninvasive, high-resolution imaging method. Here, we introduce the adaptive optics rolling slit ophthalmoscope, a unique noninvasive, label-free, high-speed, cellular-resolution clinical imaging system for assessing retinal NVC in the living human eye. Using an off-axis phase contrast approach combined with camera-based confocal slit gating, our method provides large field-ofview imaging of arterial and venular walls, enabling the study of vascular dynamics with unprecedented spatiotemporal precision. Our findings highlight that this level of precision is essential for accurately distinguishing NVC-driven vasodilation from spontaneous fluctuations, such as vasomotion and the cardiac cycle. By bridging the gap between fundamental neurovascular research and clinical applications, this approach offers a powerful tool for neuroscience research and early disease detection and monitoring of neurodegenerative and vascular disorders.Le couplage neurovasculaire (NVC) régule le flux sanguin local en réponse à l'activité neuronale, mais l'absence de méthode d'imagerie non invasive et à haute résolution empêche sa caractérisation précise à l’échelle des capillaires. Ici, nous présentons l'ophtalmoscope rolling-slit (à fente roulante), un système d'imagerie clinique unique, non invasif, sans marquage, qui acquière des images de la rétine à haute cadence et à résolution cellulaire, pour évaluer le NVC rétinien dans l'œil humain in-vivo. En utilisant une approche de détection hors axe générant du contraste de phase combinée au filtrage confocal par la fente roulante de caméra rétinienne, notre méthode permet une imagerie sans distorsion des parois artérielles et veineuses, rendant possible l'étude de la dynamique vasculaire avec une précision spatio-temporelle sans précédent. Nos résultats montrent que ce niveau de précision est essentiel pour distinguer avec exactitude la vasodilatation induite par le NVC des fluctuations spontanées, telles que la vasomotion et le cycle cardiaque. En faisant le lien entre la recherche fondamentale sur le réseau neurovasculaire et les applications cliniques, cette approche offre un nouvel outil puissant pour la recherche en neurosciences, ainsi que pour la détection précoce et le suivi des maladies neurodégénératives et vasculaires
Transport of soft matter in complex and confined environments
No full textInternational audienceBrownian motion provides a bedrock for the understanding of soft condensed matter and, therefore, of the physical description of the microscopic biological world. Inspired by this domain, and combining softness with hydrodynamic energy inputs, new physical modes of nanoscale organization and transport may now be accessible
Novel insights into vascular dysfunction in cuprizone-induced demyelination through functional ultrasound imaging
No full textInternational audienceMultiple Sclerosis (MS) is an autoimmune disease of the central nervous system (CNS), affecting 2.8 million people worldwide, that presents multiple features, one of which is demyelination. Although treatments exist to manage the condition, no cure has been found to stop the progression of neurodegeneration. To develop new treatments and investigate the multiple systems impacted by MS, new imaging technologies are needed at the preclinical stage. Functional ultrasound imaging (fUS) has recently emerged as a robust method to measure brain cerebral blood volume (CBV) dynamics as an indirect indicator of neural activity. This study aimed to quantify the amplitude of alteration of evoked hemodynamic response in the somatosensory cortex, and its potential link with demyelination in a mouse model of CNS demyelination induced by cuprizone. We demonstrate that extended demyelination leads to an increased hemodynamic response in the primary sensory cortex, both spatially and temporally, aligning with fMRI findings in MS patients. Second, using descriptors of the evoked cortical hemodynamic response, we demonstrate that certain parameters (the number of active pixels and the rise time) correlate with the level of Myelin Basic Protein in the primary sensory cortex and the thalamus, when taken together. Interestingly, the increased CBV is not associated with demyelination but instead reflects the well-documented vascular alteration described in MS. Moreover, these changes were absent in the thalamus, and in focalized demyelinated lesions induced by lysolecithin injection, suggesting the involvement of specific cortical mechanisms driven by oligodendrocyte depletion. In conclusion, our study introduces a novel, non-invasive functional approach for investigating vascular dysfunction in the context of MS, addressing an important yet understudied aspect in both pre-clinical and clinical research
Electroactive molecular layers produced by reduction of an aryldiazonium salt scrutinized by Tip Enhanced Raman Spectroscopy
No full textInternational audienceSurface modification methodologies are continuously refined, which in parallel necessitates accurate analytical methods to probe their chemical composition at the nanoscale. We describe here our electrochemical and Tip Enhanced Raman Spectroscopy results on surfaces modifiedthrough reduction of an electroactive aryldiazonium salt. Grafting may be first triggered electrochemically. In this case, thick and disorganized layers are produced, with important changes in spectral responses in comparison to the parent system. Conversely, spontaneous reduction of the salt also occurs during simple immersion in the diazonium solution, which leads to low surface coverages (i.e. thin layers) and preservation of the molecular backbone of the molecule. This study highlights the advantages of TERS to recover chemical information at the nanoscale even for complex surface modification processes
Triblock copolymers, comprising cyclic anhydride moieties, acting as reactive re-processing enhancers for polyamides
No full textInternational audienceCarbonate-and ether-based oligodiols have been converted into macro-RAFT agents via ATRAF reactions. They have been utilized in RAFT polymerization of styrene and maleic anhydride (MA) to obtain triblock copolymers (TBCs) with poly(styrene-co-maleic anhydride) side blocks. These copolymers have been used as chain extenders and tensile strength modifiers for polyamides (PAs) during reactive extrusion, which mimics mechanical recycling. TBCs of different chain lengths, number of MA moieties per chain, and stiff-to-elastic block ratio were utilized. The additives offset PA degradation during polymer processing. After 25 min of mixing (~5 recycling acts), the melt viscosity of PAs have increased at least by over five times (from 55 to around 300 Pa s for PA12 and from 5 to 25 Pa s for PA6). The tensile strength of the blends was unchanged for PA12 and increased for PA6 (up to 17 %). The materials were stiffened by the presence of rigid side blocks (up to 40 % rise in Young's modulus). The type and weight fraction of oligodiol and the amount of TBC used affected the results. The presence of TBCs did not influence the morphology of the materials.</div
Nanoparticules d'or stabilisées par des polyoxotungstates : comment passer d'une suspension aqueuse à CH3CN ?
No full textInternational audienceThe present study aims to evaluate available methods for preparing suspensions of gold nanoparticles stabilized by polyoxometalates (POMs@AuNPs) in CH3CN, a solvent commonly used in oxidation reactions. POMs@AuNPs are successfully synthesized in CH3CN using three different approaches: i) in situ generation of nanoparticles via chemical reduction of the HAuCl4 precursor with various reducing agents in CH3CN in the presence of POMs; ii) formation of POMs@AuNPs by reducing HAuCl4 with NaBH4 in the presence of [PW11O39]7− or [AsW9O33]9− in aqueous solution, followed by transfer into CH3CN after centrifugation; and iii) transfer of aqueous suspensions of Au0 nanoparticles, obtained by reducing HAuCl4 with NaBH4 and subsequent centrifugation, into CH3CN, followed by the addition of soluble organic salts of [PW12O40]3− or [AsW9O33{PO(CH2)2CO2H}2]5−. These strategies, inspired by literature, are used to assess their strengths and limitations regarding translation to CH3CN. The resulting suspensions are characterized by UV-Vis spectroscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy analysis, dynamic light scattering, and zeta potential measurements. The most stable suspensions are obtained by transferring an aqueous suspension initially stabilized with a mixture of citrate ions and tannic acid into acetonitrile. Subsequent exchange with polyoxometalates in CH3CN results in negligible changes in nanoparticle size or suspension stability
Taxonomic revision of the SK 15 mandible based on bone and tooth structural organization
No full textInternational audienceThe hominin mandible SK 15 was discovered in April 1949 in Swartkrans Member 2, dated to ∼1.4 Ma. Albeit distorted on the right side, the left and right corpus of SK 15 are relatively low and thick, even compared to most Early to Middle Pleistocene Homo specimens. It preserves the left molar row and the right M2 and M3 that show a distalward increase in mesiodistal diameter. SK 15 was originally attributed to Telanthropus capensis but is now generally attributed to Homo erectus/Homo ergaster, even if it was previously suggested to possibly belong to Australopithecus. Similarities between SK 15 and Homo naledi mandible and tooth morphology were also claimed. To clarify the taxonomy of SK 15, we used X-ray microtomography to investigate aspects of bone and tooth structural organization. Geometric morphometric analyses of the dental arcade shape, mandible symphysis outline, and the M2 and M3 enamel-dentine junction shape were conducted. For mandibular symphysis shape, SK 15 exhibits an australopith signal, whereas for both the dental arcade and enamel-dentine junction analyses, the specimen is statistically classified as Paranthropus. Altogether, the results show that SK 15 unambiguously falls outside the variation of H. erectus/H. ergaster and that it is most compatible with the morphology of Paranthropus, albeit showing smaller dimensions and an absence of some dental morphological features (e.g., developed protostylid, distally tapering M3, short molar roots) typically found in specimens of Paranthropus aethiopicus, Paranthropus boisei, and Paranthropus robustus. In particular, SK 15 differs markedly in size and morphology from mandibular remains of P. robustus from Swartkrans Member 2. We thus tentatively attribute SK 15 to Paranthropus capensis, a more gracile species of Paranthropus than the other three currently recognized species of this genus and discuss the implications for the existence of another species of Paranthropus in southern Africa during the Early Pleistocene