Contribution à la mesure de champs de température bi- et tridimensionnels par Photographie de Speckle: application à l\u27estimation des flux de chaleur pariétaux

Ce travail est consacré à la mise en uvre d\u27un dispositif optique de Photographie de Speckle dédié à la mesure des champs de température dans les écoulements d\u27air bidimensionnels et tridimensionnels et plus particulièrement à l\u27estimation des transferts thermiques en proche paroi. Dans un premier temps, le dispositif expérimental est conçu et optimisé pour l\u27étude d\u27objets de phase thermiques. Puis, une métrologie originale est développée pour l\u27estimation du aux convectif pariétal. Elle permet, notamment, d\u27accroître significativement la résolution spatiale et la précision des mesures en présence de forts gradients de température et de s\u27affranchir des phénomènes de diffraction qui introduisent un biais important lors d\u27une mesure pariétale. Cette nouvelle approche est validée avec succès, lors d\u27une campagne de mesure menée, sur un écoulement d\u27impact de jet d\u27air plan, simultanément par Photographie de Speckle et par une méthode de référence basée sur un bilan thermique à la paroi. Enfin, un algorithme de reconstruction de champs de température tridimensionnels n\u27utilisant qu\u27une direction de mesure est développé. Cette technique présente l\u27avantage de pouvoir être utilisable dans le cadre des problématiques pariétales. Elle est mise en uvre a n d\u27estimer différents paramètres 3-D d\u27une couche limite de convection naturelle

An iterative method for temperature gradient measurements in two dimensional thermal boundary layer flows by speckle photography

International audienc

Contribution à la mesure de champs de température bi et tri-dimensionnels par photographie de Speckle (application à l'estimation des flux de chaleur pariétaux)

Ce travail est consacré à la mise en œuvre d'un dispositif optique de Photographie de Speckle dédié à la mesure des champs de température dans les écoulements d'air bidimensionnels et tridimensionnels et plus particulièrement à l'estimation des transferts thermiques en proche paroi. Dans un premier temps, le dispositif expérimental est conçu et optimisé pour l'étude d'objets de phase thermiques. Puis, une métrologie originale est développée pour l'estimation du aux convectif pariétal. Elle permet, notamment, d'accroître significativement la résolution spatiale et la précision des mesures en présence de forts gradients de température et de s'affranchir des phénomènes de diffraction qui introduisent un biais important lors d'une mesure pariétale. Cette nouvelle approche est validée avec succès, lors d'une campagne de mesure menée, sur un écoulement d'impact de jet d'air plan, simultanément par Photographie de Speckle et par une méthode de référence basée sur un bilan thermique à la paroi. Enfin, un algorithme de reconstruction de champs de température tridimensionnels n'utilisant qu'une direction de mesure est développé. Cette technique présente l'avantage de pouvoir être utilisable dans le cadre des problématiques pariétales. Elle est mise en œuvre a n d'estimer différents paramètres 3-D d'une couche limite de convection naturelleVILLEURBANNE-DOC'INSA LYON (692662301) / SudocSudocFranceF

Western Hemispheric Trade Agreements and Sustainability: Lesson From Butterflies, Hummingbirds, and Salty Anchovies

The relationship between international commerce and sustainable development is the subject of much controversy that is exacerbated by geographic boundaries that are co-jointly developed, shaped, and sustained by regional trade agreements. The outcomes of three Americas trade agreements - NAFTA, CAFTA, and USPTPA - are analyzed across three dimensions: economic, ecological, and labor. The three dimensions collectively form for each trade region a specific ECOL niche that is concurrently subject to national variation. We propose and find that low-ECOL niches in the Americas appear to attract more foreign trade with investment. Nevertheless, this tentative finding seems not to hold for those corporations that seek out strong ECOL niche countries like Costa Rica

Mechanical and physical properties of expanded starch, reinforced by natural fibres

International audienceBiodegradable foams made from potato starch and natural fibres were obtained by extrusion. The effects of varying origins of these fibres on foam properties were studied, as well the relationships between their properties and the foam microstructure. The addition of fibres increased the expansion index and led to a significant reduction in water adsorption of starch foams, generally improving foam properties. The mechanical properties of the foams were affected by both relative humidity (RH) of storage and foam formulation. In general, as the RH increased, the foam strength decreased. The formulation presenting the best mechanical properties contained 10 wt% hemp fibre and had a maximal resistance of 4.14 MPa and a modulus of 228 MPa, corresponding to a more compact and dense microstructure

Inflammation and oxidative stress markers in type 2 diabetes patients with Advanced Carotid atherosclerosis

Abstract Background Type 2 diabetes mellitus (T2DM) is a major global health issue and a significant risk factor for atherosclerosis. Atherosclerosis in T2DM patients has been associated with inflammation, insulin resistance, hyperglycemia, dyslipidemia, and oxidative stress. Identifying molecular features of atherosclerotic plaques in T2DM patients could provide valuable insights into the pathogenesis of the disease. Methods The MASCADI (Arachidonic Acid Metabolism in Carotid Stenosis Plaque in Diabetic Patients) study aimed to investigate the increase of 2-arachidonoyl-lysophatidylcholine (2-AA-LPC) in carotid plaques from T2DM and control patients and to explore its association with plaque vulnerability as well as with blood and intra-plaque biomarkers altered during diabetes. Results In a population of elderly, polymedicated patients with advanced stage of atherosclerosis, we found that T2DM patients had higher systemic inflammation markers, such as high-sensitivity C-reactive protein (hsCRP) and IL-1β, higher levels of oxysterols, increased triglyceride levels, and decreased HDL levels as compared to control patients. Furthermore, 2-AA-LPC was significantly enriched in plaques from diabetic patients, suggesting its potential role in diabetic atherosclerosis. Interestingly, 2-AA-LPC was not associated with systemic markers related to diabetes, such as hsCRP, triglycerides, or HDL cholesterol. However, it was significantly correlated with the levels of inflammatory markers within the plaques such as lysophospholipids and 25-hydroxycholesterol, strengthening the link between local inflammation, arachidonic acid metabolism and diabetes. Conclusion Our study is in line with a key role for inflammation in the pathogenesis of diabetic atherosclerosis and highlights the involvement of 2-AA-LPC. Further research is needed to better understand the local processes involved in the alteration of plaque composition in T2DM and to identify potential therapeutic targets. Trial registration The MASCADI was registered on ClinicalTrials.gov (clinical registration number: NCT03202823)

Regulation of glycolytic genes in human macrophages by oxysterols: a potential role for Liver X receptors Oxysterols modulate glycolysis in human macrophages

International audienceBackground and purpose: Subset of macrophages within the atheroma plaque displays a high glucose uptake activity. Nevertheless, the molecular mechanisms as well as the pathophysiological significance of this high glucose need remain unclear. While a role for hypoxia and hypoxia inducible factor 1α has been demonstrated, the contribution of lipid microenvironment and more specifically oxysterols is yet to be explored.Experimental approach: Human macrophages were conditioned in the presence of homogenates from human carotid plaques and expression of genes involved in glucose metabolism was quantified. Correlative analyses between gene expression and the oxysterol composition of plaques were performed.Key results: Conditioning of human macrophages by plaque homogenates induces expression of several genes involved in glucose uptake and glycolysis including glucose transporter 1 (GLUT1), and hexokinases 2 and 3 (HK2 and HK3), This activation is significantly correlated to the oxysterol content of the plaque samples and is associated with a significant increase in the glycolytic activity of the cells. Pharmacological inverse agonist of the oxysterol receptor Liver X Receptor (LXR) partially reverses the induction of glycolysis genes without affecting macrophage glycolytic activity. Chromatin immunoprecipitation analysis confirms the implication of LXR in the regulation of GLUT1 and HK2 CONCLUSIONS AND IMPLICATIONS: While our work supports a role of oxysterols and LXR in the modulation of macrophage metabolism in atheroma plaques, it also highlights some LXR-independent effects of plaques samples. Finally, this study identifies the hexokinase HK3 as a promising target in the context of atherosclerosis

Interplay between Liver X Receptor and Hypoxia Inducible Factor 1a Potentiates Interleukin-1b Production in Human Macrophages

International audienceLow-grade inflammation is constitutive of atherosclerosis, and anti-inflammatory therapy inhibiting interleukin-1β (IL-1β) reduces the rate of cardiovascular events. While cholesterol accumulation in atheroma plaque and macrophages is a major driver of the inflammatory process, the role of the LXR cholesterol sensors remains to be clarified. Murine and human macrophages were treated with LXR agonists for 48 h before Toll-like receptor (TLR) stimulation. Unexpectedly, we observe that, among other cytokines, LXR agonists selectively increase IL1B mRNA levels independently of TLR activation. This effect, restricted to human macrophages, is mediated by activation of HIF-1α through LXR. Accordingly, LXR agonists also potentiate other HIF-1α-dependent pathways, such as glycolysis. Treatment of human macrophages with carotid plaque homogenates also leads to induction of IL1B in an LXR-dependent manner. Thus, our work discloses a mechanism by which cholesterol and oxysterols trigger inflammation in atherosclerosis. This suggests perspectives to target IL-1β production in atherosclerotic patients