Laboratoire sur puce pour la séparation et détection des particules à base de diélectrophorèse à basse tension

Résumé Notre recherche est construite autour de la volonté de développer et d'élargir l'utilisation des laboratoires sur puce (LsP), d'y intégrer de nouvelles fonctions et de proposer des approches de modélisation plus rigoureuses. En effet, les travaux de pointe montrent que pour réaliser des modèles mimant le plus fidèlement possible les systèmes vivants, les LsP doivent évoluer des simples supports fonctionnalisés que sont les puces d'analyse et de séparation de l'ADN vers des systèmes intégrant davantage de fonctions. Pour ce faire, nous proposons tout d'abord un premier prototype d'un LsP comprenant des modules microélectroniques, microfluidiques, de communication radio fréquence et d'alimentation intégrée, pour la séparation des particules avec des validations in-vitro. Cette plateforme a pour objectif d'observer le comportement des particules face à une variation de la fréquence, de la phase ou de l'amplitude du champ électrique avec différentes architectures d'électrodes. De plus, étant programmable et reconfigurable, elle nous a permis de valider plusieurs concepts, notamment l'identification fréquentielle des micro et nanoparticules. Cette dernière représente notre principale contribution qui pourrait, éventuellement, ouvrir la porte à plusieurs recherches notamment celles portant sur l'identification des maladies neurodégénératives. Notre but étant d’offrir une grande flexibilité dans la modélisation, nous présentons une nouvelle approche pour modéliser les LsP dans laquelle le comportement des particules est modélisé en tenant compte de l'architecture des électrodes, des signaux appliqués et des propriétés biologiques du milieu. Cette première modélisation en son genre est une approche hybride combinant une modélisation par éléments finis à l’aide d’ANSYS et une implémentation d’un algorithme sur Matlab. Elle permet de calculer la position d'une particule dans un microcanal en se basant sur les résultats fournis par ANSYS. Cette modélisation présente de nombreux avantages dont notamment, la possibilité d’identifier l’emplacement d'une particule avec précision en 3D, en plus de valider la séparation des particules à travers toute la profondeur du microcanal, ce qui n'est pas possible en se basant uniquement sur les résultats expérimentaux. De plus, nous avons fabriqué le système complet avec une architecture 3D de 5 PCB, une plateforme microfluidique, un contrôle sans fil par Bluetooth et un bloc d'alimentation programmable et intégré dans un même microsystème. Toute la partie microélectronique du LsP a été implémentée sur une puce microélectronique fabriquée avec la technologie CMOS 0.18 um de TSMC. Quant à l'architecture microfluidique, elle a été fabriquée avec les procédé Sensonit et Lionix.----------Abstract Our research project is devoted to develop and extend the use of laboratories on chip (LoC), and to add to them new functions and more rigorous modeling techniques. Without a doubt, the state of art shows that, in order to create models that reflect living organisms best, LoCs need be more evolved systems that serve more functions than simple and limited-function DNA chips. To do so, we propose a first prototype of a Lab on Chip with microelectronic and microfluidic modules, and integrated radio-frequency communication and power supply to separate the different particles in the cerebrospinal fluid with validations done in vitro. The purpose of this platform is to observe the particles' behaviour when facing a change in the electric field's, frequency, phase, or amplitude, all this using different architectures of electrodes. Moreover, the platform is programmable and reconfigurable, which is important as it allows the validation of many concepts, such as the frequency separation of micro and nanoparticles. This platform actually represents our main focus in this research. We believe that it will eventually lead to many other research and medical advancements, such as identifying the source of many degenerative neurological disorders. We also came up with an innovative approach to give a greater flexibility to the modeling of LoCs. This approach consists of modeling the behaviour of particles based on the architectural design of the electrodes, the applied signals, and the biological properties of the medium. This first type of modeling is based on a hybrid approach between a Finete element modeling using ANSYS, and an algorithmic implementation on Matlab that makes it possible to calculate each particle's position in a micro canal based on the results provided by ANSYS. Such modeling has many advantages; for example, it can precisely identify the location of a particle in 3D, as well as separate the particles throughout the whole micro canal, all of which is not possible based on experimental results. Also, we built this system entirely with a 3D architecture of PCB, a microfluidic platform, a Bluetooth wireless controller, and a source of power supply integrated all in one microsystem. The whole microelectronic part of the LoC is put on a microelectronic chip made with the CMOS 0.18 um TSMC technology. As for the microfluidic architecture, it was fabricated using both the Sensonit and Lionix processes

Input sequence estimation and blind channel identification in HF communication

Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Sciences of Bilkent Univ., 1999.Thesis (Master's) -- Bilkent University, 1999.Includes bibliographical references leaves 37-40.Ben Hadj Miled, Mohamed KhamesM.S

Immobilized Rhizopus oryzae lipase catalyzed synthesis of palm stearin and cetyl alcohol wax esters: Optimization by Response Surface Methodology

<p>Abstract</p> <p>Background</p> <p>Waxes are esters of long-chain fatty acids and long-chain alcohols. Their principal natural sources are animals (sperm whale oil) and vegetables (jojoba) which are expensive and not easily available. Wax esters synthesized by enzymatic transesterification, using palm stearin as raw material, can be considered as an alternative to natural ones.</p> <p>Results</p> <p>Palm stearin is a solid fraction obtained by fractionation of palm oil. Palm stearin was esterified with cetyl alcohol to produce a mixture of wax esters. A non-commercial immobilized lipase from <it>Rhizopus oryzae </it>was used as biocatalyst. Response surface methodology was employed to determine the effects of the temperature (30-50°C), the enzyme concentration (33.34-300 IU/mL), the alcohol/palm stearin molar ratio (3-7 mol/mol) and the substrate concentration (0.06-0.34 g/mL) on the conversion yield of palm stearin. Under optimal conditions (temperature, 30°C; enzyme concentration, 300 IU/mL; molar ratio 3 and substrate concentration 0.21 g/mL) a high conversion yield of 98.52% was reached within a reaction time of 2 h.</p> <p>Conclusions</p> <p>Response surface methodology was successfully applied to determine the optimum operational conditions for synthesis of palm stearin based wax esters. This study may provide useful tools to develop economical and efficient processes for the synthesis of wax esters.</p

Hybrid modeling method for a DEP based particle manipulation

In this paper, a new modeling approach for Dielectrophoresis (DEP) based particle manipulation is presented. The proposed method fulfills missing links in finite element modeling between the multiphysic simulation and the biological behavior. This technique is amongst the first steps to develop a more complex platform covering several types of manipulations such as magnetophoresis and optics. The modeling approach is based on a hybrid interface using both ANSYS and MATLAB to link the propagation of the electrical field in the micro-channel to the particle motion. ANSYS is used to simulate the electrical propagation while MATLAB interprets the results to calculate cell displacement and send the new information to ANSYS for another turn. The beta version of the proposed technique takes into account particle shape, weight and its electrical properties. First obtained results are coherent with experimental results

Guide d'orientation à l'approche bi-plurilingue ELAN de la lecture-écriture

Un guide pratique pour proposer aux enseignants des éléments afin de réussir l’apprentissage de la lecture-écriture au cours des trois premières années de la scolarisation

Effects of olive oil and its fractions on oxidative stress and the liver's fatty acid composition in 2,4-Dichlorophenoxyacetic acid-treated rats

<p>Abstract</p> <p>Background</p> <p>Olive oil's beneficial effects are not only related to its high content of oleic acid, but also to the antioxidant potential of its polyphenols. In this study, we assess the effects of virgin olive oil and its fractions on 2,4-D- induced oxidative damage in the liver of rats.</p> <p>Methods</p> <p>Male Wistar rats were randomly divided into eight groups of ten each: (C) a control group, (D) group that received 2,4-D (5 mg/kg b.w.), (D/EVOO) group treated with 2,4-D plus extra virgin olive oil, (D/OOHF) group that received 2,4-D plus hydrophilic fraction, (D/OOLF) group treated with 2,4-D plus lipophilic fraction, (EVOO) group that received only extra virgin olive oil, (OOHF) group given hydrophilic fraction and (OOLF) group treated with lipophilic fraction. These components were daily administered by gavage for 4 weeks.</p> <p>Results</p> <p>A significant liver damage was observed in rats treated with 2,4-D via increased serum levels of transaminases and alkaline phosphatase, hepatic lipid peroxidation and decreased hepatic antioxidant enzyme activities, namely, superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase. The liver's fatty acid composition was also significantly modified with 2,4-D exposure. However, extra virgin olive oil and hydrophilic fraction intake during 2,4-D treatment induced a significant increase in the antioxidant enzyme activities and a decrease in the conjugated dienes (CD) and thiobarbituric acid-reactive substances (TBARs) levels in the liver. The lipophilic fraction supplemented to 2,4-D- treated rats did not show any improvement in the liver oxidative status while a marked improvement was detected in the hepatic fatty acid composition of rats supplemented with olive oil and the two fractions.</p> <p>Conclusion</p> <p>We concluded that the protective effect of olive oil against oxidative damage induced by 2,4-D is mainly related to the antioxidant potential of its hydrophilic fraction.</p

Brain MRI and biological diagnosis in five Tunisians MLD patients

Metachromatic leukodystrophy (MLD) is a recessive autosomal disease which is characterized by an accumulation of sulfatides in the central and peripheral nervous system. It is due to the enzyme deficiency of the sulfatide sulfatase i.e. arylsulfatase A (ASA). we studied 5/200 cases of MLD and clearly distinguished three clinical forms. One of them presented the juvenile form; two presented the late infantile form; and two other presented the adult form. The Magnetic Resonance Imaging (MRI) of these patients showed a diffuse, bilateral and symmetrical demyelination. The biochemical diagnosis of MLD patients evidencing the low activity of ASA and sulfatide accumulation