Procédé d’agglomération et de recyclage en compactés de poudres de bauxites

National audienceLa bauxite est un minerai utilisé pour l’élaboration de l’aluminium ou directement sous forme de matière première pour la fabrication d’aluminates de calcium pour les ciments techniques. Elle est, dans ce dernier cas, essentiellement utilisée sous forme de bloc. On assiste depuis quelques années, à une raréfaction des blocs de bauxite alors que leur manipulation conduit souvent à des déchets sous forme de poussières qui ne sont pas valorisées à l’heure actuelle. L’objectif de ces travaux est de créer une nouvelle filière de recyclage de fines particules minérales pour pouvoir réutiliser cette matière première en remplacement de ressources naturelles qui s’épuisent. Ces produits sont mis en forme sous forme de compactés par compression directe. La bauxite est mélangée à du ciment et de l’eau puis introduite dans une matrice afin de subir un cycle de compression. Le compacté obtenu est ensuite stocké à température et hygrométrie contrôlées pour obtenir une hydratation maitrisée du ciment. Le compacté ainsi obtenu doit répondre à des spécifications bien précises en termes de densité, de porosité et de résistance mécanique grâce notamment aux hydrates spécifiques formés.L’outil principal utilisé pour caractériser les compactés est la micro tomographie par rayons X, qui est non destructive et permet d’observer en leur cœur même le comportement des grains et l’homogénéité en densité dans tout le volume. Les propriétés importantes des blocs telles que la porosité ou la distribution de taille des pores sont alors caractérisées grâce à l’analyse d’image des clichés de tomographie et comparé à la porosimétrie par intrusion de mercure. Cette étude de l’évolution des paramètres texturaux des compactés de bauxite doit permettre de comprendre et d’appréhender les phénomènes se déroulant pendant l’étape de compression. Il en suivra une optimisation des paramètres de compression et de mélange pour obtenir des compactés possédant les propriétés souhaitées

Low temperature (down to 450° C) annealed TiAl contacts on N-type gallium nitride characterized by differential scanning calorimetry

International audienceThis work reports on Differential Scanning Calorimetry (DSC) measurements performed on Ti-Al metallic layers stacks deposited on n+-GaN. The aim is to get better understanding of the mechanisms leading to ohmic contact formation during the annealing stage. Two exothermic peaks were found, one below 500°C and the other one around 660°C. They can be respectively attributed to Al3Ti and Al2Ti compounds formation. The locations of these peaks provide clear evidence of solid-solid reac-tions. Lowest contact resistance is well correlated with the presence of Al3Ti compound, corresponding to Al(200nm)/Ti(50nm) stoichiometric ratio. Subsequently, Al(200 nm)Ti(50 nm) stacks on n+-GaN were annealed from 400°C to 650°C. Specific Contact Resistivity (SCR) values stay in the mid 10-5 Ω.cm² range for annealing temperatures between 450°C and 650°C. Such low-temperature annealed contacts on n+-GaN may open new device processing routes, simpler and cheaper, in which Ohmic and Schottky contacts are annealed together

Front Pediatr

BACKGROUND: Nutritional status is a major prognostic factor for breathing and the survival of patients with cystic fibrosis (CF). Since 2012, the development of CFTR modulators has considerably transformed the outcome of this disease. Indeed, both lung function and body mass index are improved by CFTR modulators, such as Lumacaftor/Ivacaftor. However, few data exist regarding the outcome of nutritional intakes under Lumacaftor/Ivacaftor. METHODS: We conducted a prospective single-center study in children with CF treated with Lumacaftor/Ivacaftor to evaluate their nutritional intake before and after treatment. RESULTS: Thirty-four children were included in this study, with a median age of 12.4 years [11.9; 14.7]. There was no significant improvement in weight, height or BMI. Patients' total energy intake was not significantly changed with Lumacaftor/Ivacaftor, while carbohydrate intakes decreased significantly. We found that blood levels of vitamin E and Selenium were significantly increased under Lumacaftor/Ivacaftor, without a significant increase in supplementation. In patients with a BMI Z-score < 0 at treatment initiation, there was a significant improvement in weight and BMI Z-score, while TEI and carbohydrate intakes were significantly lower. CONCLUSION: We showed that treatment with Lumacaftor/Ivacaftor improved the nutritional status of patients without necessarily being associated with an increase in nutritional intake. Although these data need to be confirmed in larger cohorts, they support the hypothesis that weight gain under modulators is multifactorial, and may be related to a decrease in energy expenditure or an improvement in absorption

Nutritional impact of CFTR modulators in children with cystic fibrosis

BackgroundNutritional status is a major prognostic factor for breathing and the survival of patients with cystic fibrosis (CF). Since 2012, the development of CFTR modulators has considerably transformed the outcome of this disease. Indeed, both lung function and body mass index are improved by CFTR modulators, such as Lumacaftor/Ivacaftor. However, few data exist regarding the outcome of nutritional intakes under Lumacaftor/Ivacaftor.MethodsWe conducted a prospective single-center study in children with CF treated with Lumacaftor/Ivacaftor to evaluate their nutritional intake before and after treatmentResultsThirty-four children were included in this study, with a median age of 12.4 years [11.9; 14.7]. There was no significant improvement in weight, height or BMI. Patients' total energy intake was not significantly changed with Lumacaftor/Ivacaftor, while carbohydrate intakes decreased significantly. We found that blood levels of vitamin E and Selenium were significantly increased under Lumacaftor/Ivacaftor, without a significant increase in supplementation. In patients with a BMI Z-score &lt; 0 at treatment initiation, there was a significant improvement in weight and BMI Z-score, while TEI and carbohydrate intakes were significantly lower.ConclusionWe showed that treatment with Lumacaftor/Ivacaftor improved the nutritional status of patients without necessarily being associated with an increase in nutritional intake. Although these data need to be confirmed in larger cohorts, they support the hypothesis that weight gain under modulators is multifactorial, and may be related to a decrease in energy expenditure or an improvement in absorption

Deletion of Running-Induced Hippocampal Neurogenesis by Irradiation Prevents Development of an Anxious Phenotype in Mice

Recent evidence postulates a role of hippocampal neurogenesis in anxiety behavior. Here we report that elevated levels of neurogenesis elicit increased anxiety in rodents. Mice performing voluntary wheel running displayed both highly elevated levels of neurogenesis and increased anxiety in three different anxiety-like paradigms: the open field, elevated O-maze, and dark-light box. Reducing neurogenesis by focalized irradiation of the hippocampus abolished this exercise-induced increase of anxiety, suggesting a direct implication of hippocampal neurogenesis in this phenotype. On the other hand, irradiated mice explored less frequently the lit compartment of the dark-light box test irrespective of wheel running, suggesting that irradiation per se induced anxiety as well. Thus, our data suggest that intermediate levels of neurogenesis are related to the lowest levels of anxiety. Moreover, using c-Fos immunocytochemistry as cellular activity marker, we observed significantly different induction patterns between runners and sedentary controls when exposed to a strong anxiogenic stimulus. Again, this effect was altered by irradiation. In contrast, the well-known induction of brain-derived neurotrophic factor (BDNF) by voluntary exercise was not disrupted by focal irradiation, indicating that hippocampal BDNF levels were not correlated with anxiety under our experimental conditions. In summary, our data demonstrate to our knowledge for the first time that increased neurogenesis has a causative implication in the induction of anxiety

Clinical and MRI long term evolution of intracavernous and carotid ophtalmic artery aneurysms, treated by common carotid ligation.

In four large, 15-25 mm, internal carotid artery aneurysms (3 intracavernous and 1 carotid ophthalmic), treatment by common carotid ligation was preferred. Pre- and postoperative MRI were obtained, at a delay between 5 to 9 years. Recovery of the ocular and visual symptomatology was a function of the role played by mechanical and/or ischaemic factors. No early or late consequences, ascribable to the common carotid ligation, were observed. Aneurysmal thrombosis occurred in the first postoperative week, but retraction of the thrombosed aneurysms was only obvious and maximal after several months. For this reason, rapid clinical recovery could be due, in the first instance, to the loss of aneurysmal pulsatility. Complete disappearance of the aneurysm was observed in two cases. In the other two, a small remnant of the initial lesion, without any unfavourable consequences, was revealed, respectively 6 and 9 years after the intervention, by current, modern-days, MRA

A Case Study Of The Stochastic Modeling Approach For Range Estimation

International audienceThe floating-point to fixed-point conversion is an important part of the hardware design in order to obtain efficient implementations. In order to optimize the integer word-length under performance constraints, the dynamic variations of the variables during execution must be determined. Traditional range estimation methods based on simulations are data dependent and time consuming whereas analytical methods like interval and affine arithmetic give pessimistic results as they lack of a statistical background. Recently, a novel approach, based on the Karhunen-Loève Expansion (KLE) was presented for linear time-invariant (LTI) systems offering a solid stochastic foundation. Our paper presents an implementation of this theory and shows its efficiency for an OFDM modulator test case study. We also present a review of the uncertainty quantifications problem and the different phases of the range estimation methodology

Stochastic Modeling for Floating-point to Fixed-point Conversion

International audienc

Procédé d’Agglomération et de Recyclage en Compactés de poudres de bauxites (PARC)

National audienceLa bauxite est un minerai utilisé pour l’élaboration de l’aluminium ou directement sous forme de matière première pour la fabrication d’aluminates de calcium pour les ciments techniques. Elle est, dans ce dernier cas, essentiellement utilisée sous forme de bloc. On assiste depuis quelques années, à une raréfaction des blocs de bauxite alors que leur manipulation conduit souvent à des déchets sous forme de poussières qui ne sont pas valorisées à l’heure actuelle. L’objectif de ces travaux est de créer une nouvelle filière de recyclage de fines particules minérales pour pouvoir réutiliser cette matière première en remplacement de ressources naturelles qui s’épuisent. Ces produits sont mis en forme sous forme de compactés par compression directe. La bauxite est mélangée à du ciment et de l’eau puis introduite dans une matrice afin de subir un cycle de compression. Le compacté obtenu est ensuite stocké à température et hygrométrie contrôlées pour obtenir une hydratation maitrisée du ciment. Le compacté ainsi obtenu doit répondre à des spécifications bien précises en termes de densité, de porosité et de résistance mécanique grâce notamment aux hydrates spécifiques formés.L’outil principal utilisé pour caractériser les compactés est la micro tomographie par rayons X, qui est non destructive et permet d’observer en leur cœur même le comportement des grains et l’homogénéité en densité dans tout le volume. Les propriétés importantes des blocs telles que la porosité ou la distribution de taille des pores sont alors caractérisées grâce à l’analyse d’image des clichés de tomographie et comparé à la porosimétrie par intrusion de mercure. Cette étude de l’évolution des paramètres texturaux des compactés de bauxite doit permettre de comprendre et d’appréhender les phénomènes se déroulant pendant l’étape de compression. Il en suivra une optimisation des paramètres de compression et de mélange pour obtenir des compactés possédant les propriétés souhaitées