Crossover between Rayleigh-Taylor Instability and turbulent cascading atomization mechanism in the bag-breakup regime

The question whether liquid atomization (or pulverization) resorts to instability dynamics (through refinements of Rayleigh-Plateau, Rayleigh-Taylor or Kelvin-Helmholtz mechanism) or to turbulent cascades similar to Richardson and Kolmogorov first ideas seems to be still open. In this paper, we report experimental evidences that both mechanisms are needed to explain the spray drop PDF obtained from an industrial nozzle. Instability of Rayleigh-Taylor kind governs the size of the largest droplets while the smallest ones obey a PDF given by a turbulent cascading mechanism resulting in a log-L\'evy stable law of stability parameter close to 1.68. This value, very close to the inverse of the Flory exponent, can be related to a recent model for intermittency modeling stemming from self-avoiding random vortex stretching.Comment: new alpha version (precedent was a draft

Elevated soluble Flt1 mediates an anti-angiogenic state in patients with ANCA-associated vasculitis

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Variants in the GPR146 Gene Are Associated With a Favorable Cardiometabolic Risk Profile

BACKGROUND: In mice, GPR146 (G-protein-coupled receptor 146) deficiency reduces plasma lipids and protects against atherosclerosis. Whether these findings translate to humans is unknown. METHODS: Common and rare genetic variants in the GPR146 gene locus were used as research instruments in the UK-Biobank. The Lifelines, and The Copenhagen-City Heart Study, and a cohort of individuals with familial hypobetalipoproteinemia were used to find and study rare GPR146 variants. RESULTS: In the UK-Biobank, carriers of the common rs2362529-C allele present with lower low-density lipoprotein cholesterol, apo (apolipoprotein) B, high-density lipoprotein cholesterol, apoAI, CRP (C-reactive protein), and plasma liver enzymes compared with noncarriers. Carriers of the common rs1997243-G allele, associated with higher GPR146 expression, present with the exact opposite phenotype. The associations with plasma lipids of the above alleles are allele dose-dependent. Heterozygote carriers of a rare coding variant (p.Pro62Leu; n=2615), predicted to be damaging, show a stronger reductions in the above parameters compared with carriers of the common rs2362529-C allele. The p.Pro62Leu variant is furthermore shown to segregate with low low-density lipoprotein cholesterol in a family with familial hypobetalipoproteinemia. Compared with controls, carriers of the common rs2362529-C allele show a marginally reduced risk of coronary artery disease (P=0.03) concomitant with a small effect size on low-density lipoprotein cholesterol (average decrease of 2.24 mg/dL in homozygotes) of this variant. Finally, mendelian randomization analyses suggest a causal relationship between GPR146 gene expression and plasma lipid and liver enzyme levels. CONCLUSIONS: This study shows that carriers of new genetic GPR146 variants have a beneficial cardiometabolic risk profile, but it remains to be shown whether genetic or pharmaceutical inhibition of GPR146 protects against atherosclerosis in humans

Liver and Muscle in Morbid Obesity: The Interplay of Fatty Liver and Insulin Resistance

INTRODUCTION: Nonalcoholic fatty liver disease (NAFLD) can be seen as a manifestation of overnutrition. The muscle is a central player in the adaptation to energy overload, and there is an association between fatty-muscle and -liver. We aimed to correlate muscle morphology, mitochondrial function and insulin signaling with NAFLD severity in morbid obese patients. METHODS: Liver and deltoid muscle biopsies were collected during bariatric surgery in NAFLD patients. NAFLD Activity Score and Younossi's classification for nonalcoholic steatohepatitis (NASH) were applied to liver histology. Muscle evaluation included morphology studies, respiratory chain complex I to IV enzyme assays, and analysis of the insulin signaling cascade. A healthy lean control group was included for muscle morphology and mitochondrial function analyses. RESULTS: Fifty one NAFLD patients were included of whom 43% had NASH. Intramyocellular lipids (IMCL) were associated with the presence of NASH (OR 12.5, p<0.001), progressive hepatic inflammation (p = 0.029) and fibrosis severity (p = 0.010). There was a trend to an association between IMCL and decreased Akt phosphorylation (p = 0.059), despite no association with insulin resistance. In turn, hepatic steatosis (p = 0.015) and inflammation (p = 0.013) were associated with decreased Akt phosphoryation. Citrate synthase activity was lower in obese patients (p = 0.047) whereas complex I (p = 0.040) and III (p = 0.036) activities were higher, compared with controls. Finally, in obese patients, complex I activity increased with progressive steatosis (p = 0.049) and with a trend with fibrosis severity (p = 0.056). CONCLUSIONS: In morbid obese patients, presence of IMCL associates with NASH and advanced fibrosis. Muscle mitochondrial dysfunction does not appear to be a major driving force contributing to muscle fat accumulation, insulin resistance or liver disease. Importantly, insulin resistance in muscle might occur at a late point in the insulin signaling cascade and be associated with IMCL and NAFLD severity

COMPARATIVE STUDY OF OXYHEMOGLOBIN RADIOLYSIS AND THERMOLYSIS BY MÖSSBAUER SPECTROSCOPY

L'étude des modifications en fonction de la dose du spectre Mössbauer de globules rouges artériels irradiés aux rayons X montre que l'irradiation de l'oxyhémoglobine globulaire entraîne la production d'une forme déoxy ligand free probablement quickly reacting comme dans le cas, bien connu, de la photodissociation ainsi que d'une hémoglobine ferrique high spin. Pour des doses de radiation croissantes, l'hème de ces radioproduits est détruit et un composé final du type ferrique high spin à environnement rhomboédrique est produit. Ces résultats sont obtenus par comparaison avec les spectres RPE. La spectrométrie Mössbauer montre que les mêmes composés sont produits sous l'action de la chaleur, à l'exclusion de la forme déoxy ligand free.The study of variations in the Mössbauer spectrum of X-irradiated arterial red cells as a function of dose shows that irradiation of red cells oxyhemoglobin leads to the production of a ligand free deoxy form, probably fast-reacting as in the well-known case of photodissociation, and of a high spin ferric hemoglobin. For increasing radiation doses the heme of these radioproducts is destroyed and a final compound of the type high spin ferric in rhombic environment is produced. These results are obtained by comparison with EPR spectra. Mössbauer spectrometry shows that these same compounds, excluding the «ligand free» deoxy form, are formed by the action of heat

Fragmentation of a liquid metal droplet falling in a water pool

International audienceThis paper focuses on the experimental investigation of breakup regimes of a molten fusible metallic droplet in water, at intermediate Weber numbers with emphasis on mass and energy balance. The experiment consists in impacting perpendicularly a molten drop onto the interface of a deep water pool, at a controlled temperature. Using a drop-ondemand device and high speed shadowgraph, a single drop can be visualized during its evolution. There is a noticeable velocity jump when the droplet crosses the interface that can be modeled using unsteady Bernoulli equation. As observed for liquid-gas systems, the drop experiences different regimes of fragmentation, depending on its Weber number: oscillations, bag oscillations, prolate drop stretching breakup and then bowl-shaped bag breakup. However opposite to the gas-liquid case, Rayleigh-Taylor instability mechanism seems to be absent and this seems related to the bowl-shaped bag breakup mechanism when compared to the dome-shaped gas-liquid case. Statistics of the daughter droplets are then given, using either image analysis for large droplets size distribution or sieving and weighting of the solidified fragments for measurement of Sauter Mean Diameter (SMD) and surface energy creation. Lastly, a simple relation between the SMD and the Weber number is presented based on energy and mass balances. When comparing with previous higher Weber number results, a viscous transition corresponding to a strong increase in the energy loss is also shown to occur for the higher Weber number

Classification of ablation mode during impact of hot liquid jet on a solid

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Assessing the Containment Efficiency of a Microbiological Safety Cabinet During the Simultaneous Generation of a Nanoaerosol and a Tracer Gas

International audienceThe intention of this paper is to compare the containment performance of a Type II Microbiological Safety Cabinet(MSC) confronted with the simultaneous generation of a saline nanoparticle aerosol and a tracer gas (SF6). The back dissemination coefficient, defined as the ratio of the pollutant concentration measured outside the enclosure to the pollutant flow rate emitted inside the enclosure, is calculated in order to quantify the level of protection of each airborne contaminant tested for three enclosure operating configurations: an initial configuration (without perturbations), a configuration exposing a dummy in front of the enclosure (simulation of an operator) and a configuration employing the movement of a plate in front of the enclosure (simulation of human movement). Based on the results of this study, we observed that nanoparticulate and gaseous behaviours are strongly correlated, thus showing the predominance of air driven transport over particle specific behavior. The average level of protection afforded by the MSC was found systematically slightly higher for the nanoaerosol than for the gas in the studied configurations (emission properties of the source, operating conditions, measurements protocol). This improved protection efficiency can however not be considered as a warrant of protection for operators, since operating condition and ventilation parameters are still more influent on the containment than the pollutant nature (i.e. nanoaerosol or gas)