HAL Portal ESPCI (Ecole Supérieure de Physique et de Chimie Industrielles)
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Suppressing Interfacial Instability of Immiscible Liquid‐in‐Liquid Flow Using Magnetic Forces
No full textInternational audienceInterfacial instability prevents a liquid jet from flowing indefinitely within air or another liquid. An approach is presented here to suppress interfacial instability by means of a magnetic force applied by a ferrofluid envelope around the jet. The stability limits occurring within a large parameter window are experimentally investigated with length and time scales governed by the magnetic Bond number. Instabilities can be generated by modifying the magnetic force strength externally, with a remarkable return to stability when removing the external stimulus. The current system with soft and slippery interfaces enables investigations of flow systems beyond the limits of standard hydrodynamics allowing for exciting applications in flow chemistry, interface engineering and transport of biological materials
N-heterocyclic carbenes exchange on gold nanoparticles
No full textInternational audienceN-heterocyclic carbenes (NHC) are neutral species containing a divalent carbon atom, which can be stabilized when bounded to a metal. Used as ligands in organometallic chemistry for many years, they have for some years gain interest as surface ligands for metal nanoparticles and surfaces. In addition to their high functional modularity, their main advantage is likely their capability to form strong M-C bonds, which can sustain quite harsh conditions. Actually, in several reports, NHC have been shown to perform better than thiols, the ligands classically used to stabilize gold nanoparticles.Two types of NHC have been mainly used to stabilize gold nanoparticles. The most studied one is based on the 1,3-imidazol-2-ylidene scaffold (ImNHC), which derived from imidazoliums. More recently, mesoionic carbenes (MICS), based 1,2,3-triazol-5-ylidene scaffold, have also been explored.Full exchange of sacrificial surface ligands, eg. thioether, by NHC have been one of the first method reported to prepare NHC stabilized gold nanoparticles, following a top-down approach. But partial exchange of NHC ligands by other NHC ligands to obtain gold nanoparticles stabilized by two different ligands has so far remained undocumented. Yet, such strategy yields mixed ligands AuNPs, which are valuable tools for expanding the utility and fine tuning the properties of nanoparticles, such as stability, functionality and interactions with the surrounding medium.The practicality and efficiency of various exchange strategies involving the reaction of NHC stabilized gold nanoparticles with imidazolium, triazolium, in-situ generated free NHC or NHC-Au(I) complexes has therefore been evaluated. Solution NMR was used to monitor the extend of reaction and identify possible exchange pathways. XPS was used on the isolated gold nanoparticles to quantify the exchange ratio in relation with the experimental conditions
Stress induces oxytocin-Gαi-dependent remodeling of astrocytes to shape neuronal response in the amygdala
No full textInternational audienceAnticipated reactions to stressful situations are vital for the survival and well-being of organisms, and abnormal reactions results in stress-related disorders. The neuropeptide oxytocin is a key modulator ensuring well-adapted stress responses. Oxytocin acts on both neurons and astrocytes, but the molecular and cellular mechanisms mediating stress response remain poorly understood. Here, we focus on the amygdala, a crucial hub that integrates and processes sensory information through oxytocin-dependent mechanisms. Using an acute stress paradigm in mice, genetic and pharmacological manipulations combined with proteomic, morphological, electrophysiological and behavioral approaches, we reveal that oxytocinergic modulation of the freezing response to stress is mediated by transient Gαi-dependent retraction of astrocytic processes, followed by enhanced neuronal sensitivity to extracellular potassium in the amygdala. Our findings elucidate a pivotal role for astrocytes morphology-dependent modulation of brain circuits that is required for proper anticipated behavioral response to stressful situations
Temperature-induced absolute energy shift of the electronic spectrum in HgTe nanocrystals
No full textInternational audienceMercury telluride (HgTe) nanocrystals (NCs) are promising materials for infrared photodetection due to their size-tunable band edges and compatibility with colloidal synthesis. While optical studies have established the temperature dependence of their relative bandgaps, the evolution of their absolute electronic spectrum with cooling remains poorly understood, despite its critical role in the device operation. In this work, we investigate in situ the temperature-induced absolute energy shift of HgTe NCs' electronic states with varying band edge energies, using X-ray photoemission spectroscopy. We observe a systematic and reversible rigid shift of core levels toward lower binding energies upon cooling, reaching approximately 80 meV per 100 K, four times larger than the corresponding optical band edge shift (≈20 meV). This behavior is consistent across different NC sizes, making the impact more dramatic for the narrower bandgap NCs. Such absolute energy shifts can significantly alter carrier densities and interfacial band alignments, potentially creating Schottky barriers and reducing extraction efficiency in photodiode architectures. Our findings highlight the necessity of accounting for temperature-induced absolute energy shifts in the design of next-generation HgTe NC-based infrared detectors
BAG3-related myofibrillar myopathy: focus on its cardiac involvement
No full textInternational audienceMyofibrillar myopathy is a cause of rare and severe pediatric cardiomyopathies. Few descriptions of patients carrying the rare p. Pro209Leu variant in BAG3 and presenting with myofibrillar myopathy are reported in the literature. Most reports originate from neurological teams, while the cardiac phenotype remains poorly described, even though it is crucial for prognosis, as cardiac involvement can significantly influence patient outcomes. We focused on the cardiac phenotype associated with p. Pro209Leu variant in BAG3 and conducted a literature review. We report three patients with severe restrictive cardiomyopathy (RCM) including two with left ventricular hypertrophy. Cardiac symptoms appeared 7 [5–7.5] years after neurological onset and were predominantly right heart failure, with high NT-proBNP levels, and arrhythmic events (atrial flutter, ectopic atrial tachycardia). Cardiac MRI showed biatrial and left ventricular fibrosis. Prognosis was severe, with two deaths. In the reviewed cases, cardiac involvement was present in 76.9% and diagnosed at an early age of 11 [8.2–12.7]. Restrictive cardiomyopathy was the most prevalent phenotype (69.2%), followed by hypertrophic cardiomyopathy (5.1%) and rare long or borderline QT interval (7.7%). Arrhythmias were observed in only one patient. Heart transplantation was performed in 11 patients at 13 [10.5–13.5] years, with some developing secondary neurological symptoms. Most patients lost ambulation, required ventilation support, and exhibited orthopedic involvement. Overall mortality was 30.7%, with sudden death being the most reported cause. The p. Pro209Leu variant in BAG3 is associated with progressive neurological and cardiac involvement, leading to a poor prognosis. Repeated cardiac screening is recommended in these patients and conversely, neurological progression should be monitored after transplantation in patients initially presenting with isolated RCM
Post-hybridization of MIL-101(Cr) with graphene oxide enhances its hydrogen storage and release capacities
No full textInternational audienceHydrogen (H 2 ) is a clean and high-energy carrier; however, its low volumetric energy density remains a major barrier to practical storage and transport. This study demonstrates that the hybridization of MIL-101(Cr) with graphene oxide (GO) effectively enhances H 2 storage and release capacities. The integration of GO, with a density of 450 kg m -3 , into MIL-101(Cr), a highly porous metal-organic framework (A BET ≥ 3,500 m 2 g -1 , V pore ≥ 2.0 cm 3 g -1 and 259 kg m -3 of density) was investigated through a post-synthetic hybridization strategy, leading to increased ultramicroporosity and enhanced density of the resulting hybrids. Although GO incorporation led to a reduction in gravimetric (wt.%) H 2 storage at 77 K and 100 bar, ranging from 3% to 36% as GO content increased, it significantly improved H 2 uptake at 273 K and 100 bar. The hybrid with 1 wt.% GO exhibited the most notable enhancement, achieving a 40% increase in gravimetric storage capacity (273 K, 100 bar) compared to pure MIL-101(Cr). This hybrid also demonstrated superior volumetric performance, reaching a 6% increase both in total H 2 storage, 35.8 kg m -3 (77 K, 100 bar), and deliverable capacity, 34.2 kg m -3 , under practical operating conditions (i.e., charging: 77 K and 100 bar; discharging: 160 K and 5 bar). These findings highlight the dual role of GO: densifying the composite while potentially introducing ultramicroporosity, particularly effective at elevated temperatures, offering a promising pathway toward practical, scalable, and efficient hydrogen storage systems.</div
pH gradient-driven deformation of a crista-like vesicle
No full textThe inner membrane of mitochondria presents folds, the cristae, which are the production place of ATP. This synthesis is driven by a flow of protons confined to the surface of the membrane, which also shapes the crista to ensure a high synthesis rate. We model a crista as a spherical vesicle submitted to a diffusive proton gradient flowing from the poles to the equator. Using Helfrich model, we introduce a pH-dependent spontaneous curvature for the membrane and determine the shape of the vesicle, when submitted to the pH gradient, in the regime of small deformations. Based on biophysical arguments, we define a functionality score for the vesicle and construct a phase diagram identifying the zones of "well-functioning" cristae, which we compare to experimental measurements.</div
Highly efficient Hydrogenative depolymerisation of Polycaprolactone to 1,6-hexanediol
No full textInternational audienceWe report here our study on the development of an efficient process to make 1,6-hexanediol from the hydrogenation of polycaprolactone assisted by ethanolysis. Using a ruthenium SNS pincer catalyst, a record high turnover number of 19,600 with 98% yield of 1,6-hexanediol is obtained at 80 o C and 60 bar H2 pressure. The reported method has environmental advantages over the conventional process for the production of 1,6-hexanediol, which emits a significant amount of nitrous oxide greenhouse gas
Evaluating the Performance of a Microporous Ti Bisphosphonate MOF for Postcombustion Carbon Capture by Vacuum Pressure Swing Adsorption
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蛇类基于生活习性在游泳特征上的种内与种间差异
No full textInternational audienceSnakes exhibit extraordinary ecological diversity and occupy a broad range of terrestrial, aquatic, and intermediate environments. Despite their widespread capacity for swimming, quantitative assessments of their aquatic locomotion remain scarce. Furthermore, the roles of intraspecific variation in shaping swimming performance and kinematics have been largely overlooked, hindering robust interspecific comparisons. This study systematically investigated intraspecific and interspecific variation in 287 individuals representing seven snake species along a terrestrial to aquatic continuum. Nine conventional swimming traits were quantified, including swimming speed and undulation characteristics such as frequency, wavelength, lateral velocities (head, body and tail) and amplitudes (head, body and tail). Undulation frequency and lateral velocity exhibited strong positive correlations with swimming speed, whereas wavelength showed a strong negative correlation. Semi-aquatic taxa attained the highest swimming speeds, while fully aquatic snakes displayed the lowest speeds. Intraspecific variation in swimming performance and kinematics was moderately reduced in aquatic species. Morphological traits, sex, and reproductive status significantly influenced both speed and kinematic profiles within species. Principal component analyses further revealed distinct kinematic domains among certain species (e.g., no overlap between aspic viper and sea snakes), while others, such as the green whip snake, exhibited broad overlap with all taxa examined. These findings demonstrate that ecological specialization to aquatic habitats does not unilaterally dictate swimming speed or kinematic patterns. Moreover, conventional kinematic parameters alone are insufficient to study the evolutionary trajectories of aquatic locomotion in snakes. Integrating hydrodynamic, endurance capacity, and diving performance will be essential to better understand how natural selection has shaped locomotion in aquatic snakes