HAL Portal ESPCI (Ecole Supérieure de Physique et de Chimie Industrielles)
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Dark side of the honeymoon: reconstructing the Asian x European rose breeding history through the lens of genomics
No full textInternational audienceAbstract Roses have a specific symbolic charge in Western cultural heritage, often used as a metaphor for love and romance. Despite its ancient cultivation, the passion for the phenotypic diversity of roses is relatively recent, dating back to the early 19 th century. During that century, the number of rose varieties has increased exponentially from roughly 100 to 8,000, in such a way that this period can be considered as the golden age for rose breeding. To retrace the history of rose breeding in Europe and shed new light on genetic changes during this period, we collected large phenotypic and genetic data from 204 accessions, including botanical roses and varieties bred between 1800 and 1910. We also used whole-genome sequences from 32 accessions as an extra resource. The genetic makeup of roses is remarkably consistent with a temporal shift from a historical European to a near-Asian genetic background within a few generations. Our analyses are consistent with a substantial erosion of the genetic diversity during this period, both because of the greater contribution of the Asian genepool - a less genetically diverse group - and of specific genomic footprints of selection, in particular regarding the extension of the blooming period. Thanks to this study, we have generated the largest GWAS catalog for roses to date, which can be used as a tool for future rose breeding programs. We particularly discuss the crucial importance of preserving ancient rose collections to safeguard genetic diversity and ensure a sustainable breeding for the long-term
How heat propagates in liquid 3He
No full textInternational audienceAbstract In Landau’s Fermi liquid picture, transport is governed by scattering between quasi-particles. The normal liquid 3 He conforms to this picture but only at very low temperature. Here, we show that the deviation from the standard behavior is concomitant with the fermion-fermion scattering time falling below the Planckian time, ℏ k B T and the thermal diffusivity of this quantum liquid is bounded by a minimum set by fundamental physical constants and observed in classical liquids. This points to collective excitations (a sound mode) as carriers of heat. We propose that this mode has a wavevector of 2 k F and a mean free path equal to the de Broglie thermal length. This would provide an additional conducting channel with a T 1/2 temperature dependence, matching what is observed by experiments. The experimental data from 0.007 K to 3 K can be accounted for, with a margin of 10%, if thermal conductivity is the sum of two contributions: one by quasi-particles (varying as the inverse of temperature) and another by sound (following the square root of temperature)
Characteristics and prognosis of tumor-related epilepsy during tumor evolution in patients with IDH-wildtype glioblastoma
No full textInternational audienceBackground and objectives: Tumor-related epilepsy is a well-known symptom of glioblastoma. However, the particular characteristics of epileptic seizures related to glioblastoma, isocitrate dehydrogenase (IDH)-wild-type is almost unexplored longitudinally during the whole course of the disease. We assessed tumor-related epilepsy and seizure control during tumor evolution and the prognostic significance of tumor-related epilepsy.Methods: We performed an observational, retrospective single-center study at one tertiary referral neuro-oncology surgical center (2000-2020). We included adult patients treated for a newly diagnosed supratentorial glioblastoma, IDH-wild-type with available preoperative and postoperative MRI and with available epileptic seizure status at diagnosis. To determine factors associated with tumor-related epilepsy or seizure control, univariate analyses were performed using the χ2 or Fisher exact tests for categorical variables and the unpaired t test or Mann-Whitney rank-sum test for continuous variables. Predictors associated with tumor-related epilepsy and seizure control in unadjusted analysis were entered into backward stepwise logistic regression models.Results: One thousand six patients were enrolled. The cumulative incidence of tumor-related epilepsy increased during tumor evolution (33.1% at diagnosis, 44.7% after oncologic treatment, 52.4% at progression, and 51.8% at the end-of-life phase) and is related to tumor features (cortex involvement, no necrosis, and small volume). Uncontrolled epileptic seizures increased during tumor evolution (20.1% at diagnosis, 32.0% after oncologic treatment, 46.7% at progression, and 41.1% at the end-of-life phase). Epileptic seizure control after oncologic treatment was related to seizure features (uncontrolled before oncologic treatment and focal-to-bilateral tonic-clonic seizures) and to the extent of resection. Epileptic seizure control at tumor progression was related to seizure features (presence at diagnosis and uncontrolled after oncologic treatment) and to the time to progression. Tumor-related epilepsy at diagnosis was a predictor of a longer overall survival (adjusted hazard ratio, 0.78; 95% CI 0.67-0.90; p < 0.001) independent of age, Karnofsky Performance Status score, tumor location and volume, extent of resection, standard combined chemoradiotherapy, levetiracetam use, and MGMT promoter methylation.Discussion: The progression of tumor-related epilepsy with the evolution of glioblastoma, IDH-wild-type and the effects of surgery on seizure control argue for proper antiseizure medication and maximal safe resection. Tumor-related epilepsy is an independent predictor of a longer survival
Fabrication d’une mousse élastomère magnétique, relations structure - propriétés et interactions avec le champ magnétique
No full textMagnetic soft materials are of great interest in the field of soft robotics, thanks to their ability to induce large deformations instantaneously and without physical contact, paving the way for new applications in medicine and industry. This thesis explores the potential of magnetic elastomeric foams as magnetostimulable materials. We have developed a technique for shaping model foams with open porosity based on the use of a sacrificial template obtained by compressing NaCl crystals. The template is filled with a suspension of carbonyl iron particles in polydimethylsiloxane, which is then cross-linked to form a magnetic elastomer matrix. The foam is obtained by dissolution of the template. The pressure applied during manufacture of the template enables the final porosity of the foam to be controlled with great precision between 75% and 85%. The presence of porosity in the matrix reduces its Young's modulus in compression from 1 MPa to around 5 kPa. The final foam is compressible thanks to its low Poisson's ratio of 0.15. In a magnetic field gradient, the iron particles are attracted by a volumetric magnetic force, which induces large deformations and a volume change. Using digital image correlation, we demonstrated the presence of a strong strain gradient in the sample, linked both to the distribution of the magnetic field around the magnet and to the volumetric nature of the magnetic force. By developing analytical and numerical models, we have established a relationship between the characteristics of foams (in particular, porosity and initial sample size) and the deformation induced by a magnet. We have shown the existence of an optimal foam size leading to maximum deformation. Finally, another part of the thesis explores the manufacture of polymer networks from bio-based Ricinodendron heudelotii oils. We obtained elastic polymers by spontaneous polymerization in air, without any additive. The obtained materials have Young's moduli of the order of 1 MPa and a glass transition temperature around -10°C. We demonstrate the potential of these oils for replacing the petroleum-based matrix in elastomeric foams.Les matériaux mous magnétiques présentent un grand intérêt dans le domaine de la robotique, grâce à la possibilité d'induire de grandes déformations de façon instantanée et sans contact physique. Ils ouvrent la voie à de nouvelles applications par exemple en médecine ou pour l'industrie. Cette thèse explore le potentiel des mousses élastomères magnétiques en tant que matériaux magnétostimulables. Nous avons développé une technique de mise en forme de mousses modèles à porosité ouverte basée sur l'utilisation d'un gabarit sacrificiel obtenu par compression de cristaux de NaCl. Le gabarit est rempli d'une suspension de particules de fer carbonyle dans du polydiméthylsiloxane qui est ensuite réticulé pour donner une matrice élastomère magnétique. La mousse est obtenue par dissolution du gabarit. La pression appliquée lors de la fabrication du gabarit permet de piloter avec une grande précision la porosité finale de la mousse entre 75% et 85%. La présence de porosité dans la matrice permet de réduire son module d'Young en compression de 1 MPa jusqu'à environ 5 kPa. La mousse finale est compressible avec un faible coefficient de Poisson, environ 0,15. Placées dans un gradient de champ magnétique, les particules de fer subissent une force magnétique volumique, qui induit de grandes déformations avec un changement de volume. Nous avons montré par corrélation numérique d'image la présence d'un fort gradient de déformation dans l'échantillon, lié à la fois à la distribution du champ magnétique autour de l'aimant et au caractère volumique de la force magnétique. En développant des modèles analytique et numérique, nous avons établi une relation entre les caractéristiques des mousses (en particulier, la porosité et la taille initiale de l'échantillon) et la déformation induite par un aimant. Nous avons montré l'existence d'une taille optimale de mousse conduisant à une déformation maximale. Enfin, un autre volet de thèse explore la fabrication de réseaux polymères à partir d'huiles biosourcées de Ricinodendron heudelotii. Nous avons obtenu des polymères élastiques par une polymérisation spontanée dans l'air, sans additif. Les matériaux obtenus ont des modules d'Young de l'ordre de 1 MPa et une température de transition vitreuse d'environ -10°C. Nous montrons le potentiel de ces huiles en substitution des matrices pétrosourcées pour la fabrication de mousses élastomères magnétiques
Functionality integration in stereolithography 3D printed microfluidics using a “print-pause-print” strategy
No full textInternational audienceStereolithography 3D printing, although an increasingly used fabrication method for microfluidic chips, has the main disadvantage of producing monolithic chips in a single material. We propose to incorporate during printing various objects using a “print-pause-print” strategy. Here, we demonstrate that this novel approach can be used to incorporate glass slides, hydrosoluble films, paper pads, steel balls, elastic or nanoporous membranes and silicon-based microdevices, in order to add microfluidic functionalities as diverse as valves, fluidic diodes, shallow chambers, imaging windows for bacteria tracking, storage of reagents, blue energy harvesting or filters for cell capture and culture
Near-field characterization of Nb2CTx MXene by non-destructive nearfield microscopy
No full textInternational audienceThe Nb2CTx MXene was synthesized and optically characterized utilizing Photo-induced Force Microscopy (PiFM), a nanoscale imaging technique combining AFM topography mapping and infrared spectroscopy. In both bulk and single/few layered MXene flakes, absorption peaks were observed in the 770 - 1860 cm-1 investigated range. The local IR spectra is compared with broader Fourier-transform infrared (FTIR) and Raman spectroscopy to analyse the material composition. Our findings notably highlight the presence of a characteristic peaks related to surface functional group in both far-field and near-field measurement. The spectra also indicate a strong contribution of niobium oxide in the synthetized material
Microglia maintain structural integrity during fetal brain morphogenesis
No full textInternational audienceMicroglia (MG), the brain-resident macrophages, play major roles in health and disease via a diversity of cellular states. While embryonic MG display a large heterogeneity of cellular distribution and transcriptomic states, their functions remain poorly characterized. Here, we uncovered a role for MG in the maintenance of structural integrity at two fetal cortical boundaries. At these boundaries between structures that grow in distinct directions, embryonic MG accumulate, display a state resembling post-natal axon-tract-associated microglia (ATM) and prevent the progression of microcavities into large cavitary lesions, in part via a mechanism involving the ATM-factor Spp1. MG and Spp1 furthermore contribute to the rapid repair of lesions, collectively highlighting protective functions that preserve the fetal brain from physiological morphogenetic stress and injury. Our study thus highlights key major roles for embryonic MG and Spp1 in maintaining structural integrity during morphogenesis, with major implications for our understanding of MG functions and brain development
Synthesis of New Glycine-based Polymers and their Thermoresponsive Behavior in Water
No full textInternational audienceIn this work, we develop new glycine‐derived polymers that exhibit thermoresponsive properties in water. Therefore, a series of monomers containing one, two or three amide functional groups and one terminal cyanomethyl group is synthesized. The resulting homopolymers, obtained by free radical polymerization (FRP) and reversible addition fragmentation chain transfer (RAFT) polymerization, display a sharp and reversible upper critical solution temperature (UCST)‐type phase transition in water. Additionally, we show that the cloud point can be adjusted over more than 60 °C by the number of glycyl groups present in the monomer structure and by the polymer's molar mass. These novel thermoresponsive polymers based on cyanomethylglycinamide enrich the range of non‐ionic UCST polymers and are promising to find applications in various fields
Curvature tuning through defect-based 4D printing
No full textInternational audienceEmerging 4D printing techniques have enabled the realization of smart materials whose shape or properties can change with time. Two important phenomena play important roles in the 4D printing of shape memory polymeric materials. First, the anisotropic deformation of the printed filaments due to residual stresses can be harnessed to create out-of-plane shape transformations. Second, the unavoidable formation of micro-defects during the printing processes often affects the programmability of the printed object. Here, we propose a design approach that harnesses these two effects occurring during fused deposition modeling to create tailor-made curved geometries from initially 2D flat disks. We first determined the size and distribution of the imperfections formed within printed structures by varying two printing parameters namely the printing speed and the number of printed materials. Spatially varying the printing speed and combining polylactic acid filaments with a softer material without shape memory properties allowed us to cover a variety of shapes from negative to positive values of the mean and Gaussian curvature. We propose an analytical model to calculate the magnitude of the maximum out-of-plane deformation from the anisotropic expansion factor of the constituting microstructures. Furthermore, we develop computational models to predict the complex shape-changing of thermally actuated 4D printed structures given the distribution of rationally introduced imperfections and we demonstrate the potential applications of such defect-based metamaterials in drug delivery systems
Ising-like model replicating time-averaged spiking behaviour of in vitro neuronal networks
No full textInternational audienceWe analyze time-averaged experimental data from in vitro activities of neuronal networks. Through a Pairwise Maximum-Entropy method, we identify through an inverse binary Ising-like model the local fields and interaction couplings which best reproduce the average activities of each neuron as well as the statistical correlations between the activities of each pair of neurons in the system. The specific information about the type of neurons is mainly stored in the local fields, while a symmetric distribution of interaction constants seems generic. Our findings demonstrate that, despite not being directly incorporated into the inference approach, the experimentally observed correlations among groups of three neurons are accurately captured by the derived Ising-like model. Within the context of the thermodynamic analogy inherent to the Ising-like models developed in this study, our findings additionally indicate that these models demonstrate characteristics of second-order phase transitions between ferromagnetic and paramagnetic states at temperatures above, but close to, unity. Considering that the operating temperature utilized in the Maximum-Entropy method is T o = 1 , this observation further expands the thermodynamic conceptual parallelism postulated in this work for the manifestation of criticality in neuronal network behavior