HAL Portal ESPCI (Ecole Supérieure de Physique et de Chimie Industrielles)
Not a member yet
13939 research outputs found
Sort by
Effects on gas-liquid flows of the enhanced stability of bubbles in liquid mixtures
No full textInternational audienc
Effect of bubble size on the stability of flowing liquid films in binary oil mixtures
No full textInternational audienc
Non-brownian capillary suspensions: effect of shape and secondary fluid fraction on structure and rheological behavior
No full textInternational audienc
Transcranial brain-wide functional ultrasound and ultrasound localization microscopy in mice using multi-array probes
No full textInternational audienceFunctional ultrasound imaging (fUS) and ultrasound localization microscopy (ULM) are advanced ultrasound imaging modalities for assessing both functional and anatomical characteristics of the brain. However, the application of these techniques at a whole-brain scale has been limited by technological challenges. While conventional linear acoustic probes provide a narrow 2D field of view and matrix probes lack sufficient sensitivity for 3D transcranial fUS, multi-array probes have been developed to combine high sensitivity to blood flow with fast 3D acquisitions. In this study, we present a novel approach for the combined implementation of transcranial whole-brain fUS and ULM in mice using a motorized multi-array probe. This technique provides high-resolution, non-invasive imaging of neurovascular dynamics across the entire brain. Our findings reveal a significant correlation between absolute cerebral blood volume (ΔCBV) increases and microbubble speed, indicating vessellevel dependency of the evoked response. However, the lack of correlation with relative CBV (rCBV) suggests that fUS cannot distinguish functional responses alterations across different arterial vascular compartments. This methodology holds promise for advancing our understanding of neurovascular coupling and could be applied in brain disease diagnostics and therapeutic monitoring.</div
Exploring canine’s olfactive threshold in artificial urine for medical detection
No full textInternational audienceCanine olfaction is increasingly studied as a tool for detecting cancer and other diseases. Previous pilot studies have demonstrated that dogs can effectively distinguish positive samples from negative samples in humans with breast cancer, achieving sensitivity rates as high as 100%. However, questions remain about dogs’ ability to detect low concentrations of volatile organic compounds in complex medium. While dogs’ detection thresholds for isoamyl acetate using a mineral oil substrate have been studied, there are no current studies on their detection limits using more complex substrates like urine, relevant in clinical settings. This pilot study aimed to evaluate the olfactory threshold of dogs using artificial urine with various concentrations of isoamyl acetate. Two dogs were trained to detect isoamyl acetate, initially using water as the substrate during the training phase, and subsequently using artificial urine during the testing phase, under single and double-blinded conditions. The dogs were trained to indicate the presence of isoamyl acetate solutions by sitting in front of the positive sample and ignoring controls. Training and testing occurred in a controlled environment, maintaining consistency with the same two handlers, a standardized methodology, and positive reinforcement with toy rewards. Based on double-blind performances, results showed a minimum detection threshold of 6.7 x 10-9 Molar (M) for Nougaro (Springer Spaniel) one dog and 2.1 x 10-7M for Prince (Labrador Retriever). The sample age did not affect performance. However, the position of the cone did, with higher failure rates for the first cone compared to the other three. These findings underscore the potential of trained dogs to detect volatile organic compounds at very low concentrations in complex substrates, supporting their use in clinical diagnostics
Mutant emergence timing and population immunisation status impact epidemiological dynamics
No full textInternational audienceA key question in evolutionary epidemiology is to determine differences in the conditions that may allow some mutant strains to spread in a population where a resident strain is already circulating. Evolutionary invasion analyses assume that the immunity is long-lasting for previously infected individuals making it difficult to study traits such as immune escape. We relax this last assumption and allow the environment faced by the mutant to fluctuate outside of any epidemiological equilibrium. We introduce an original two-strains non-Markovian model that accounts for realistic immunity waning and cross-immunity, inspired by the case of SARS-CoV-2 variants. We show that mutants with increased contagiousness or with some immune escape abilities are more likely to invade the population. We also show that the timing of the introduction of mutant strain in the population is key because it is associated with the population's immunisation status. Our results underline the importance of immune waning and non-equilibrium dynamics on infectious disease evolution
Western diet since adolescence impairs brain functional hyperemia at adulthood in mice: rescue by a balanced ω-3:ω-6 polyunsaturated fatty acids ratio
No full textInternational audienceBackground/Objective: Obesity is a devastating worldwide metabolic disease, with the highest prevalence in children and adolescents. Obesity impacts neuronal function but the fate of functional hyperemia, a vital mechanism making possible cerebral blood supply to active brain areas, is unknown in organisms fed a high-caloric Western Diet (WD) since adolescence.Subjects/Methods: We mapped changes in cerebral blood volume (CBV) in the somatosensory cortex in response to whisker stimulation in adolescent, adult, and middle-aged mice fed a WD since adolescence. To this aim, we used non-invasive and high-resolution functional ultrasound imaging (fUS). Results:We efficiently mimicked the metabolic syndrome of adolescents in young mice with early weight gain, dysfunctional glucose homeostasis, and insulinemia. Functional hyperemia is compromised as early as 3 weeks of WD and remains impaired after that in adolescent mice. Starting WD in adult mice does not trigger the profound impairment in sensory-evoked CBV observed in young mice, suggesting a cerebrovascular vulnerability to WD during adolescence. In WD, ω-6:ω-3 polyunsaturated fatty acids (PUFAs) ratio is unbalanced towards proinflammatory ω-6. A balanced ω-6:ω-3 PUFAs ratio in WD achieved by docosahexaenoic acid supplementation efficiently restores glucose homeostasis and functional hyperemia in adults.Conclusions: WD triggers a rapid impairment in cerebrovascular activity in adolescence, which is maintained at older ages, and can be rescued by a PUFA-based nutraceutical approach.</div
Synthetic Aspects and Characterization Needs in MOF Chemistry – from Discovery to Applications
No full textInternational audienceEven if MOFs are recently developed for large‐scale applications, the road to applications of MOFs is long and rocky. This requires to overcome challenges associated with phase discovery, synthesis optimization, basic and advanced characterization, and computational studies. Lab‐scale results need to be transferred to large‐scale processes, which is often not trivial, and life‐cycle analyses and techno‐economic analyses need to be performed to realistically assess their potential for industrial relevance. Based on the experience in the field of stable, functional MOFs combining advanced synthesis, characterization, and modeling, this mini‐review gives recommendations especially for non‐specialists, for example, from chemical engineers to medical doctors, to accelerate and facilitate knowledge transfer which will ultimately lead to the application of MOFs. The recommendations will include the reporting of synthesis and characterization data as well as standardization and detailed information required for the application of data mining and machine learning techniques, which are increasingly used to accelerate the discovery of new materials and data analysis. Once a suitable MOF is identified and its key properties determined, translational studies shall finally be carried out in collaboration with end‐users to validate performance under real conditions and allow understanding of the processes involved
Electric charges as an apparent governing parameter for electron induced stress relaxation in amorphous silica micropillars
No full textInternational audienceWe report a new approach on the phenomenon of plastic flow induced by electron irradiation in amorphous silica, revealing that the total injected electric charge is the governing parameter of the mechanical response: micropillar relaxation tests conducted under electron irradiation showed a one-to-one relationship between the injected electric charge and the measured mechanical stress level, regardless of the applied current. Moreover, by performing these tests at high temperature, we have found that the effects of electronic processes and temperature are decoupled. This result suggests that under the present irradiation/temperature conditions, the density of flow defects is controlled only by irradiation, while the plastic rearrangement of the defects depends only on temperature
Désinfection par peroxyde d'hydrogène à faible concentration dans l'air : le rôle clé de la condensation
No full textInternational audienceGazeous hydrogen peroxide (H2O2 ) is commonly used for disinfection of room surfaces or sterilization of medical devices. Disinfection and sterilization processes are controlled by mean values measured at sterilizer chamber or room level. However, the surface phenomena (adsorption/ condensation) taking place on inoculum are essential and still not well-known. In the present study, a solution of water and H2O2 is sprayed in a room disinfection system (Glosair 400, ASP) for 12min. Condensation mass, H2O2 concentration, relative humidity (RH), macro zoom observations and inactivation kinetics of various microorganisms (Staphyloccocus aureus, Pseudomonas aeruginosa Candida albicans, Aspergillus niger) are reported. Macro-zoom observations reveal condensation and bubbling activities. Microbial inactivation is found optimal at low initial RH, corresponding to high H2O2 vapor concentration and low condensed mass. H2O2 concentration in the condensate is high and probably boosted by fractional condensation. In surface disinfection processes, inactivation of microorganisms occurs in presence of condensation although excessive condensation, due to high initial RH conditions or the presence of salt, decreases the microbial inactivation efficiency by dilution. While the present experimental conditions differ from those prevailing in H2O2 sterilization (59 % H 2 O 2 under vacuum) or industrial disinfection processes (30% H2O2 at atmospheric pressure), they are partially transposable.Le peroxyde d'hydrogène gazeux (H2O2) est couramment utilisé pour la désinfection des surfaces des locaux ou la stérilisation des dispositifs médicaux. Les processus de désinfection et de stérilisation sont contrôlés par des valeurs moyennes mesurées au niveau de la chambre ou de la pièce du stérilisateur. Cependant, les phénomènes de surface (adsorption/condensation) qui se produisent sur l'inoculum sont essentiels et encore mal connus. Dans la présente étude, une solution d'eau et de H2O2 est pulvérisée dans un système de désinfection des locaux (Glosair 400, ASP) pendant 12 minutes. La masse de condensation, la concentration en H2O2, l'humidité relative (HR), les observations macro-zoom et la cinétique d'inactivation de divers micro-organismes (Staphyloccocus aureus, Pseudomonas aeruginosa Candida albicans, Aspergillus niger) sont rapportées. Les observations macro-zoom révèlent des activités de condensation et de bullage. L'inactivation microbienne est optimale à une faible humidité relative initiale, correspondant à une concentration élevée de vapeur de H2O2 et à une faible masse condensée. La concentration en H2O2 dans le condensat est élevée et probablement augmentée par condensation fractionnée. Dans les procédés de désinfection de surface, l'inactivation des micro-organismes se produit en présence de condensation, bien qu'une condensation excessive, due à des conditions initiales d'humidité relative élevées ou à la présence de sel, diminue l'efficacité de l'inactivation microbienne par dilution. Bien que les conditions expérimentales actuelles diffèrent de celles qui prévalent dans les procédés de stérilisation au H2O2 (59 % H2O2 sous vide) ou de désinfection industrielle (30 % H2O2 à pression atmosphérique), elles sont partiellement transposables