The Kolmogorov Law of turbulence, What can rigorously be proved ? Part II

International audienceWe recall what are the different known solutions for the incompressible Navier-Stokes Equations, in order to fix a suitable functional setting for the probabilistic frame that we use to derive turbulence models, in particular to define the mean velocity and pressure fields, the Reynolds stress and eddy viscosities. Homogeneity and isotropy are discussed within this framework and we give a mathematical proof of the famous −5/3 Kolmogorov law, which is discussed in a numerical simulation performed in a numerical box with a non trivial topography on the ground

Lipid nanocapsules maintain full integrity after crossing a human intestinal epithelium model

Lipid nanocapsules (LNCs) have demonstrated great potential for the oral delivery of drugs having very limited oral bioavailability (BCS class II, III and IV molecules). It has been shown previously that orally-administered LNCs can permeate through mucus, increase drug absorption by the epithelial tissue, and finally, increase drug bioavailability. However, even if transport mechanisms through mucus and the intestinal barrier have already been clarified, the preservation of particle integrity is still not known. The aim of the present work is to study in vitro the fate of LNCs after their transportation across an intestinal epithelium model (Caco-2 cell model). For this, two complementary techniques were employed: Förster Resonance Energy Transfer (FRET) and Nanoparticle Tracking Analysis (NTA). Results showed, after 2 h, the presence of nanoparticles in the basolateral side of the cell layer and a measurable FRET signal. This provides very good evidence for the transcellular intact crossing of the nanocarriers

Etude aéroacoustique de configurations génériques de dispositifs hypersustentateurs (approches analytique et expérimentale)

Depuis plusieurs décennies, le trafic aérien ne cesse de croître. Ainsi, près de 6 milliards de passagers transitent dans le monde par an. Les objectifs européens à l horizon 2020 en terme d émission sonore des aéronefs imposent une réduction de 10 dB par point de mesure par rapport aux aéronefs de l an 2000. Dans ce contexte, le projet européen VALIANT (VALidation and Improvement of Airframe Noise prediction Tools) a pour but principal de tester, valider et améliorer les codes numériques et les modèles de prédiction du bruit de cellule (trains d atterrissage + voilure) sur des géométries simplifiées afin de disposer de cas tests pour les recherches futures. L objectif de la thèse, associé à la contribution de l ECL dans ce projet, est de créer des bases de données expérimentales fiables sur des systèmes à deux éléments bec/aile et aile/volet et de modéliser analytiquement le bruit issu de tels systèmes. La thèse s est concentrée sur un système aile/volet non porteur et parallèle dans un écoulement de soufflerie à veine ouverte, en configuration d alignement ou de recouvrement partiel, menant à de possibles interactions aérodynamiques et/ou acoustiques. Les mesures ont été faites pour différentes vitesses d écoulement (30 100 m~s), avec une attention particulière à 50 m~s (M0 0, 15). Le taux de turbulence de l écoulement incident est modifiable par l ajout d une grille de turbulence à maille large placée dans la section de sortie du convergent. Les résultats aérodynamiques (fil chaud, pression en paroi) ont révélé la présence d une forte interaction lorsque la distance entre les deux corps est de l ordre de grandeur de la couche limite turbulente au bord de fuite de l aile. De plus, le couplage acoustique a lieu lorsque la longueur de recouvrement est positive ou nulle. Des mesures de localisation de sources menées par l ONERA/DSNA ont permis de valider les mesures de champ lointain en confirmant l absence de sources de bruit d installation en dessous de 10 kHz. Par ailleurs, des comparaisons avec les simulations numériques donnent de bons accords. Du point de vue analytique, le problème mathématique de deux plaques planes en recouvrement partiel dans un écoulement uniforme a été posé et une réduction bidimensionnelle a été justifiée. Le problème n ayant pas de solution exacte, plusieurs modèles issus de la littérature théories de Howe et d Amiet ont été étudiés. Les plus pertinents ont été confrontés aux résultats expérimentaux, révélant les limites asymptotiques de ces modèles. Un modèle original est alors proposé pour la géométrie du problème posé, sans hypothèse restrictive. La démarche est basée sur une procédure de diffraction itérative permettant de prendre en compte la proximité des deux corps et utilisant la fonction de Green exacte du demi-plan en écoulement uniforme. Le modèle prédit des comportements qualitatifs angle/fréquence proches des résultats expérimentaux. La prise en compte de la statistique des rafales incidentes reste néanmoins à effectuer afin de procéder à des comparaisons quantitatives. Une campagne expérimentale complémentaire avec une marche descendante permet de mettre en évidence les écoulements de cavité arrière d une aile, plus proche de la réalité. De même, des mesures sur une configuration bec/aile a été testée et la prise en compte de la déflexion du jet de la soufflerie pour la réfraction des ondes sonores par la couche de cisaillement a été proposée.Air traffic still grows from decades, with yearly 6 billion passengers nowadays in the world. By 2020, the EC imposes aircraft noise reductions by 10 dB per measuring point with respect to the status in 2000. In this context, VALIANT (VALidation and Improvement of Airframe Noise prediction Tools) is an EC-supported project that aims at testing, validating and improving numerical codes and analytical/theoretical models for the prediction of airframe noise (landing gears + high-lift devices) in simplified configurations in order to generate test cases for research needs. The main objective of the thesis in connection with ECL contribution in the scope of VALIANT project is to generate reliable experimental databases for 2-element systems slatwing and wing-flap as well as to analytically model overlapping configurations. It is particulary focussed on the experimental and analytical studies of a non lifting wing-flap system in a parallel flow, in aligned and overlapping arrangements. This is aimed at discussing likely aerodynamic and/or acoustic interactions. The tests have been carried out in an open-jet anechoic wind-tunnel for each arrangement and for several flow speeds (30-100 m/s), with main interest on 50 m/s (M0 0, 15). The turbulence rate could be changed by fixing a removable turbulence grid with a large mesh at the outlet cross-section of the duct. Aerodynamic results (hot-wire anemometry, wall-pressure) show a strong interaction when the wing-flap distance is about the wing trailingedge boundary layer thickness. Acoustic coupling can be pointed out in cases of overlap. Source localization tests performed by ONERA/DSNA have permitted to validate far-field acoustic tests since no installation effect source seems to strongly radiate below 10 kHz. A good agreement with numerical simulations has been shown for every test. In order to predict noise analytically for a 2-element system in case of overlap in a uniform flow, the mathematical statement has been defined and a 2D-reduction of the equation system can be justified. Since no exact solution exists, several models from the literature Howe s and Amiet s theories have been studied. Comparisons between overlapping half-planes and slotted trailing-edge models proposed by Howe and experimental results show obvious limitations in the predictions. Then, an original model is proposed involving two bodies in close overlap arrangement, with no assumption. It is based on an iterative scattering procedure to take into account the close vicinity of the two bodies, using the exact half-plane Green s function in a uniform flow. Convergence is relatively quick and qualitative predictions in angle/frequency behaviour show a good agreement with experiments. However, the statistics of the vortical flows responsible for the sound must be implemented for better comparisons. Other experiments have been done with a backward-facing step it represents wing trailing-edge cove to make cavity flow mechanisms appear, such as what is observed in real HLD. Finally, a series of tests has been performed involving a slat-wing system and an angular correction due to refraction of sound waves in shear-layer for a deflected jet has been proposed.LYON-Ecole Centrale (690812301) / SudocSudocFranceF

Formulation and evaluation of new oxazaphosphorine prodrugs-loaded lipid nanocapsules for cancer treatment

Oxazaphosphorines (cyclophosphamide (CPA) and ifosfamide (IFO)) represent an important group of therapeutic molecules due to their substantial antitumor and immunomodulating activities. Unfortunately, despite the benefits brought by these molecules, their clinical use shows limitations, notably in chemotherapy, due to the development of resistance, interpatients variation and toxicities (urinary toxicity, neurotoxicity and nephrotoxicity). To circumvent these problems, new oxazaphosphorine analogs have been synthetized and present an interesting anti-tumor activity alone with reduced toxicity [1]. Pentanoxy moiety has been grafted on C4 position of ifosfamide (P-IFO). Nevertheless, these new analogs are lipophilic and unstable in aqueous medium. To administer it, this paper proposes to formulate this analog into nanocarriers. Lipid nanocapsules form a new generation of nanovector that can encapsulate a number of anticancer agents [2]. In the present research, P-IFO-loaded LNCs were formulated and characterized. A new formulation based on glycerol monooleate (Peceol®) was developed, optimized and then characterized. Batches of P-IFO-LNCs were obtained with a size of 47.2±0.7nm with a narrow size distribution and a drug payload of 8.42±1.05mg/g. The suspension remained stable at 4°C for 14 days in terms of mean particle size, polydispersity index and pH. The drug payload decreased after 7 days but a high rate was still found (5.88±1.01mg/g) up to 14 days. The stealth properties of these nanoparticles were examined in vitro using the complement activation (CH50) test. This test revealed a low consumption of plasma protein in the presence of such P-IFO-LNCs. In vitro cytotoxicity of P-IFO-LNCs was determined in two human cell lines; i.e. rhabdomyosarcoma (RMS-1) and Ewing sarcoma (A673) and showed a similar activity compared to the free form. Finally, in vivo activity testing of P-IFO-LNCs is in progress in a murine model bearing a RMS-1 xenograft after intravenous administration. References [1] Skarbek C, et al., Preactivated Oxazaphosphorines Designed for Isophosphoramide Mustard Delivery as Bulk Form or Nanoassemblies: Synthesis and Proof of Concept. Journal of Medicinal Chemistry. 22;58(2):105-17, 2015. [2] Huynh NT, et al., Lipid nanocapsules: A new platform for nanomedicine. International Journal of Pharmaceutics. 379(2):201–9, 2009. Acknowledgments: The authors are very grateful to the Ligue contre le Cancer, Comité du Maine et Loire and Comité d’Ille et Vilaine which founded this work

De evaluatie van bodemerosie op de neolithische site van Ottenburg/Grez-Doiceau

This contribution reports on the investigations at the Neolithic site of Ottenburg, located in the loess area of Flanders. The research must lead to the evaluation of the preservation of this archaeological site with regard to both historic and present-day water and tillage erosion. Additionally, it serves as a test case for the use of the newly developed highresolution digital terrain model (DTM) of Flanders. The identification of historic erosion is based on the current depths of (calcareous loess and clay illuviation) soil horizons, detected by means of hand augeringthe current erosion is simulated with a spatially distributed erosion and sediment delivery model. At Ottenburg, the results of both approaches correspond quite well, allowing the identification of four zones with a different magnitude of soil erosion. Taking into account the established extension of the Neolithic site, based on the distribution of artefacts at the surface and microtopographic features identified on the DTM, a number of site management guidelines are proposed. Ultimately, this should result in the elaboration of a detailed site management plan

Nanocapsules lipidiques, procédé de préparation et utilisation comme médicament

The present invention relates to nanocapsules, including: a core essentially consisting of a fatty substance, which is liquid or semi-liquid at ambient temperature, and including a hydrophobic active principle and a diethylene glycol ether; an outer lipid shell which is solid at ambient temperature. The lipid nanocapsules of the invention are intended in particular for the manufacture of a drug