Les comportements orientés vers un but sont complexes et font appel à un grand nombre de processus cérébraux. Le cortex préfrontal médian (mPFC) apparaît comme une structure clef dans la réalisation de ces comportements de par son rôle dans la planification. De plus, il existe au sein du mPFC des cellules signalant les lieux à forte valeur motivationnelle. L’activité de ces neurones pourrait être essentielle à la mise en place d’un comportement spatial dirigé vers un but. S’orienter vers un but nécessite aussi la construction d’une représentation stable de l’environnement, qui repose sur l’activité de l’hippocampe (HPC). Néanmoins, peu de travaux ont analysé le rôle respectif de ces deux structures, et leurs interactions, lors de l’acquisition et de la consolidation d’une stratégie comportementale orientée vers un but. L’objectif des recherches réalisées au cours de ma thèse est donc d’étudier l’implication de l’hippocampe et du cortex préfrontal médian du rat dans ce processus. Notre première étude a montré l’existence d’un codage prospectif au sein des neurones du mPFC durant la réalisation d’une tâche de mémoire de travail.L’activité des neurones signale à la fois, la séquence temporelle comportementale, et l’anticipation de la récompense, et jouerait ainsi un rôle dans les fonctions exécutives. Dans la deuxième étude, nous nous sommes intéressés aux structures cérébrales impliquées dans la mise à jour de la valence du but ainsi que dans sa rétention à long terme. Nos résultats ont montré que l’inactivation de l’hippocampe intermédiaire provoque des déficits dans le traitement à court terme d’un changement de valence. En revanche, l’inactivation du mPFC empêche le stockage à long terme de ce changement. L’activité de ces deux structures serait donc essentielle pour effectuer une mise à jour en temps réel de la valence d’un but et pour sa consolidation en mémoire à long terme. Leur interaction permettrait d’adapter rapidement et de façon durable la stratégie comportementale de l’animal face aux changements de l’environnement. / Goal-directed behaviors are complex and involve a variety of cognitive processes. Medial prefrontal cortex (mPFC) plays a key role in behavioral planning. More over, cells in the rat mPFC show specific firing modulations at location with a high motivational value. Such neuronal activity could be essential for the setting up installation of a goal-directed behavior. Further more, navigating to a spatial goal requires the building of a stable presentation of the environment which is hippocampus-dependent. So far however, only few studies have addressed the respective role of these two structures, and their interaction, during the acquisition and the consolidation of a goal directed-behavior. The work conducted during my PhD thesis aimed at studying the role of hippocampus and prefrontal cortex in this process. In a first study,we showed the existence of a prospective coding by mPFC neurons when the rat performs a working memory task. Neuronal activity signals both, the temporal sequence of the behavior, and the prediction of reward. These neurons would play a role inexecutive functions. In a second study, we focused on cerebral structures involved in the updating of the value of a goal as well as in its long-term retention. Our results showed that the inactivation of the intermediate hippocampus causes deficit in the short-term processing of a change in the goal value. On the other hand, the inactivation of the mPFC prevents long-term consolidation of this change. Integrity of this two structures would therefore be essential to perform an on-line updating of the goal value and for its long-term consolidation. Their interaction would be necessary to rapidly adapt, and in a lasting manner, the behavioral strategy of the animal when it faces an environmental change.

No description available.

Através de Testes de Diluição em Sistema de Tubos Múltiplos determinou-se a Intensidade de Atividade de Inibição Bacteriana (IINIB/bacteriostasia) e a Intensidade de Atividade de Inativação Bacteriana (IINAB/bactericidia) de soluções conservantes contendo extrações etanólicas (alcoolatura/planta verde, hidroalcoolatura/planta seca) e hídricas (decoctos/planta verde ou seca) de Ocimum gratissimum L. (“alfavacão”, “alfavaca”, “alfavaca-cravo”) – Labiatae - (Lamiaceae), sobre inóculos padronizados de Salmonella Enteritidis (ATCC 11076), Escherichia coli (ATCC 11229) e Staphylococcus aureus (ATCC 25923). Testou-se também, a partir da formulação de quatro bebidas, duas alcoólicas e duas não alcoólicas, com e sem açúcar respectivamente, a partir de extrato reconstituido (alcoolatura/planta verde) desta planta, em diferentes concentrações (5%, 15% e 30%), através de Testes de Suspensão em Sistema de Tubos Múltiplos, a Intensidade de Atividade de Inativação Bacteriana (IINAB/bactericidia), sobre Salmonella Enteritidis (ATCC 11076), bem como a aceitabilidade/preferência sensorial por Escala Hedônica destes quatro produtos. Todas as diferentes formas de extração apresentaram capacidade de inibição e/ou inativação seletivas sobre os três inóculos bacterianos, tendo a forma de extração alcoólica apresentado a atividade antibacteriana mais intensa (inibição/inativação) frente aos três agentes. A bactéria mais sensível à atividade antibacteriana em todas as soluções conservantes foi Salmonella Enteritidis. Staphylococcus aureus apresentou a menor sensibilidade às formas de decocção, enquanto Escherichia coli apresentou a menor sensibilidade frente a forma de extração hidroalcoólica. Todas as formulações apresentaram atividade bactericida para Salmonella Enteritidis, diretamente proporcional às concentrações do extrato e ao tempo de exposição da bactéria às bebidas, destacando-se neste sentido a formulação não alcoólica com açúcar. Na análise sensorial a preferência aumentou com o decréscimo da concentração de extrato de Ocimum gratissimum na formulação. A bebida não alcoólica com açúcar, na concentração de 5% de extrato, destacou-se na preferência sensorial/aceitabilidade. / Through Dilution Tests in Multiple Tubes System, the intensity of bacterial inhibition activity (IINIB/bacteriostasys) and the intensity of bacterial inactivation activity (IINAB/bactericidie) from preservatives solutions containing etanolic extractions (alcoholature/green plant, hidroalcoholature/dry plant) and hydric extractions (decoctions/green or dry plant) of Ocimum gratissimum L. (African basil) - Labiatae - (Lamiaceae), on standardized inocula of Salmonella Enteritidis (ATCC 11076), Escherichia coli (ATCC 11229) and Staphylococcus aureus (ATCC 25923) was determined. In the same way, the Activity Intensity of Bacterial Inactivation (IINAB/bactericidie), in four drinks formulations, two alcoholic and two no-alcoholic, with and without sugar respectively, from reconstituted extract (alcoholature/green plant) of the same plant, at different concentrations (5%, 15% and 30%), on Salmonella Enteritidis (ATCC 11076) was determined by Suspension Tests in Multiple Tubes System, and the acceptability/sensory preference by Hedonic Scale of these four products. All differents extractions forms had showed selective capacity of inhibition or inactivation on the three bacterial inocula. The alcoholic extraction form presented the antibacterial activity more intense (inhibition/inactivation) against the three agents. The sensitivest bacteria by all preservatives solutions was Salmonella Enteritidis. Staphylococcus aureus showed a lower sensibility to the decoction types, while Escherichia coli showed a lower sensibility to the hydroalcoholic extraction. All food formulations showed bactericidal activity on Salmonella Enteritidis, directly proportional to the extract concentrations and the exposure time of the bacterium in beverages, pointing the not alcohol with sugar formulation. In the sensorial analysis the preference increased with the decrease of the extract concentration of Ocimum gratissimum. The non-alcoholic beverage with sugar, in the extract concentration of 5%, pointed in the sensorial preference// acceptability.

L’oxydase de l’acide 1-AminoCyclopropane Carboxylique (ACC Oxydase, ACCO) catalyse la formation de l’éthylène, hormone essentielle à la vie des plantes. L’ACCO catalyse l’oxydation de l’ACC en éthylène en présence de dioxygène et de deux électrons (fournis in vitro par l’ascorbate). L'activité de l'enzyme requière également, pour des raisons encore incomprises, la présence de CO2 sous la forme d'ions bicarbonates. Il s’agit d’une enzyme qui contient un ion fer(II) dans un environnement non-hémique au site actif. Etant donné l’importance de l’éthylène chez les plantes, l’ACCO, ainsi que les autres enzymes impliquées dans sa biosynthèse, ont été très étudiées durant les vingt dernières années. Cependant, peu d’études ont porté sur le rôle de l’ion métallique et le mécanisme d’action ou sur les surprenants processus d’inactivation subis par l’enzyme. L’ACCO est en effet une enzyme connue pour son instabilité. Nous avons tout d’abord entrepris une caractérisation physicochimique et biochimique de l’enzyme. Le matériel protéique utilisé a tout d’abord été analysé une coupure entre les résidus Ala 290 et Gly 291 a été observée au cours de la purification de l'enzyme. Puis, grâce à l'utilisation de techniques spectroscopiques, nous avons cherché à obtenir plus d'informations sur la fixation des substrats/cofacteurs au site actif. Enfin l’étude des mutants et des complexes modèles de l’ACCO a été réalisée afin de mieux comprendre le mécanisme catalytique et de rechercher de nouvelles activités. Nous nous sommes aussi intéressés aux mécanismes d’inactivation de l’ACCO. En présence des effecteurs en excès, cette inactivation se traduit par une fragmentation et une modification de charge. Lorsque la concentration en fer est limitée, aucune modification physique de l’enzyme inactive n’est observée et l'enzyme garde un contenu global en aminoacide et une conformation tridimensionnelle intègres. Des processus oxydatifs se déroulant directement au site actif de l’enzyme sont susceptibles d’engendrer une telle perte d’activité par l'oxydation d'un nombre limité d'acides aminés. Des études en spectrométrie de masse ont été entreprises et sont toujours en cours afin d'identifier les modifications responsables de la perte d'activité de l'enzyme.Enfin nous avons recherché d’éventuelles partenaires protéiques qui pourraient conférer à l’ACCO une meilleure stabilité. Des études préliminaires ont été entreprises et des données de microscopie suggèrent que l'ACCO est localisée près des membranes de la vacuole. / The 1-AminoCyclopropane Carboxylic acid oxidase (ACC Oxidase, ACCO) catalyzes the last step of the biosynthesis of the plant hormone, ethylene. ACCO catalyzes the oxidation of ACC into ethylene in the presence of dioxygen and two electrons (provided in vitro by ascorbate). Carbon dioxide (or bicarbonate ions) are also required for optimum activity. ACCO is an non-heme iron(II) containing enzyme. Given the importance of ethylene in plants, studies on ACCO, as well as on the other enzymes involved in its biosynthesis, have attracted much attention in the past two decades. However, few studies focus on the role of the metal ion and on the catalytic mechanism or the intriguing inactivation processes. ACCO is indeed known for its instability. We first purified and characterised the enzyme. During the purification, a cleavage between residues Ala 290 and Gly 291 was observed. Then, using spectroscopic techniques, we intended to get more information on cofactor's binding in the active site. Finally studies of mutants and model complexes of ACCO were performed in order to get a better understanding of the catalytic mechanism and to look for new activities.We were also interested in the inactivation processes of ACCO. In the presence of an excess of effectors, this inactivation resulted in fragmentation and in pI modification. When the concentration of iron is limited, no modifications of the inactive enzyme were observed. The inactive enzyme maintained its amino acid content and three-dimensional conformation. The loss of activity is therefore likely to derive from oxidative processes directly at the active site. Mass spectrometry experiments were initiated and are still under progress. Finally we were interested in identifying possible protein partners of ACCO that could provide a better stability. Preliminary studies were thus initiated and from microscopy results, ACCO was found located close to the vacuole membrane.

Através de Testes de Diluição em Sistema de Tubos Múltiplos determinou-se a Intensidade de Atividade de Inibição Bacteriana (IINIB/bacteriostasia) e a Intensidade de Atividade de Inativação Bacteriana (IINAB/bactericidia) de soluções conservantes contendo extrações etanólicas (alcoolatura/planta verde, hidroalcoolatura/planta seca) e hídricas (decoctos/planta verde ou seca) de Ocimum gratissimum L. (“alfavacão”, “alfavaca”, “alfavaca-cravo”) – Labiatae - (Lamiaceae), sobre inóculos padronizados de Salmonella Enteritidis (ATCC 11076), Escherichia coli (ATCC 11229) e Staphylococcus aureus (ATCC 25923). Testou-se também, a partir da formulação de quatro bebidas, duas alcoólicas e duas não alcoólicas, com e sem açúcar respectivamente, a partir de extrato reconstituido (alcoolatura/planta verde) desta planta, em diferentes concentrações (5%, 15% e 30%), através de Testes de Suspensão em Sistema de Tubos Múltiplos, a Intensidade de Atividade de Inativação Bacteriana (IINAB/bactericidia), sobre Salmonella Enteritidis (ATCC 11076), bem como a aceitabilidade/preferência sensorial por Escala Hedônica destes quatro produtos. Todas as diferentes formas de extração apresentaram capacidade de inibição e/ou inativação seletivas sobre os três inóculos bacterianos, tendo a forma de extração alcoólica apresentado a atividade antibacteriana mais intensa (inibição/inativação) frente aos três agentes. A bactéria mais sensível à atividade antibacteriana em todas as soluções conservantes foi Salmonella Enteritidis. Staphylococcus aureus apresentou a menor sensibilidade às formas de decocção, enquanto Escherichia coli apresentou a menor sensibilidade frente a forma de extração hidroalcoólica. Todas as formulações apresentaram atividade bactericida para Salmonella Enteritidis, diretamente proporcional às concentrações do extrato e ao tempo de exposição da bactéria às bebidas, destacando-se neste sentido a formulação não alcoólica com açúcar. Na análise sensorial a preferência aumentou com o decréscimo da concentração de extrato de Ocimum gratissimum na formulação. A bebida não alcoólica com açúcar, na concentração de 5% de extrato, destacou-se na preferência sensorial/aceitabilidade. / Through Dilution Tests in Multiple Tubes System, the intensity of bacterial inhibition activity (IINIB/bacteriostasys) and the intensity of bacterial inactivation activity (IINAB/bactericidie) from preservatives solutions containing etanolic extractions (alcoholature/green plant, hidroalcoholature/dry plant) and hydric extractions (decoctions/green or dry plant) of Ocimum gratissimum L. (African basil) - Labiatae - (Lamiaceae), on standardized inocula of Salmonella Enteritidis (ATCC 11076), Escherichia coli (ATCC 11229) and Staphylococcus aureus (ATCC 25923) was determined. In the same way, the Activity Intensity of Bacterial Inactivation (IINAB/bactericidie), in four drinks formulations, two alcoholic and two no-alcoholic, with and without sugar respectively, from reconstituted extract (alcoholature/green plant) of the same plant, at different concentrations (5%, 15% and 30%), on Salmonella Enteritidis (ATCC 11076) was determined by Suspension Tests in Multiple Tubes System, and the acceptability/sensory preference by Hedonic Scale of these four products. All differents extractions forms had showed selective capacity of inhibition or inactivation on the three bacterial inocula. The alcoholic extraction form presented the antibacterial activity more intense (inhibition/inactivation) against the three agents. The sensitivest bacteria by all preservatives solutions was Salmonella Enteritidis. Staphylococcus aureus showed a lower sensibility to the decoction types, while Escherichia coli showed a lower sensibility to the hydroalcoholic extraction. All food formulations showed bactericidal activity on Salmonella Enteritidis, directly proportional to the extract concentrations and the exposure time of the bacterium in beverages, pointing the not alcohol with sugar formulation. In the sensorial analysis the preference increased with the decrease of the extract concentration of Ocimum gratissimum. The non-alcoholic beverage with sugar, in the extract concentration of 5%, pointed in the sensorial preference// acceptability.

Através de Testes de Diluição em Sistema de Tubos Múltiplos determinou-se a Intensidade de Atividade de Inibição Bacteriana (IINIB/bacteriostasia) e a Intensidade de Atividade de Inativação Bacteriana (IINAB/bactericidia) de soluções conservantes contendo extrações etanólicas (alcoolatura/planta verde, hidroalcoolatura/planta seca) e hídricas (decoctos/planta verde ou seca) de Ocimum gratissimum L. (“alfavacão”, “alfavaca”, “alfavaca-cravo”) – Labiatae - (Lamiaceae), sobre inóculos padronizados de Salmonella Enteritidis (ATCC 11076), Escherichia coli (ATCC 11229) e Staphylococcus aureus (ATCC 25923). Testou-se também, a partir da formulação de quatro bebidas, duas alcoólicas e duas não alcoólicas, com e sem açúcar respectivamente, a partir de extrato reconstituido (alcoolatura/planta verde) desta planta, em diferentes concentrações (5%, 15% e 30%), através de Testes de Suspensão em Sistema de Tubos Múltiplos, a Intensidade de Atividade de Inativação Bacteriana (IINAB/bactericidia), sobre Salmonella Enteritidis (ATCC 11076), bem como a aceitabilidade/preferência sensorial por Escala Hedônica destes quatro produtos. Todas as diferentes formas de extração apresentaram capacidade de inibição e/ou inativação seletivas sobre os três inóculos bacterianos, tendo a forma de extração alcoólica apresentado a atividade antibacteriana mais intensa (inibição/inativação) frente aos três agentes. A bactéria mais sensível à atividade antibacteriana em todas as soluções conservantes foi Salmonella Enteritidis. Staphylococcus aureus apresentou a menor sensibilidade às formas de decocção, enquanto Escherichia coli apresentou a menor sensibilidade frente a forma de extração hidroalcoólica. Todas as formulações apresentaram atividade bactericida para Salmonella Enteritidis, diretamente proporcional às concentrações do extrato e ao tempo de exposição da bactéria às bebidas, destacando-se neste sentido a formulação não alcoólica com açúcar. Na análise sensorial a preferência aumentou com o decréscimo da concentração de extrato de Ocimum gratissimum na formulação. A bebida não alcoólica com açúcar, na concentração de 5% de extrato, destacou-se na preferência sensorial/aceitabilidade. / Through Dilution Tests in Multiple Tubes System, the intensity of bacterial inhibition activity (IINIB/bacteriostasys) and the intensity of bacterial inactivation activity (IINAB/bactericidie) from preservatives solutions containing etanolic extractions (alcoholature/green plant, hidroalcoholature/dry plant) and hydric extractions (decoctions/green or dry plant) of Ocimum gratissimum L. (African basil) - Labiatae - (Lamiaceae), on standardized inocula of Salmonella Enteritidis (ATCC 11076), Escherichia coli (ATCC 11229) and Staphylococcus aureus (ATCC 25923) was determined. In the same way, the Activity Intensity of Bacterial Inactivation (IINAB/bactericidie), in four drinks formulations, two alcoholic and two no-alcoholic, with and without sugar respectively, from reconstituted extract (alcoholature/green plant) of the same plant, at different concentrations (5%, 15% and 30%), on Salmonella Enteritidis (ATCC 11076) was determined by Suspension Tests in Multiple Tubes System, and the acceptability/sensory preference by Hedonic Scale of these four products. All differents extractions forms had showed selective capacity of inhibition or inactivation on the three bacterial inocula. The alcoholic extraction form presented the antibacterial activity more intense (inhibition/inactivation) against the three agents. The sensitivest bacteria by all preservatives solutions was Salmonella Enteritidis. Staphylococcus aureus showed a lower sensibility to the decoction types, while Escherichia coli showed a lower sensibility to the hydroalcoholic extraction. All food formulations showed bactericidal activity on Salmonella Enteritidis, directly proportional to the extract concentrations and the exposure time of the bacterium in beverages, pointing the not alcohol with sugar formulation. In the sensorial analysis the preference increased with the decrease of the extract concentration of Ocimum gratissimum. The non-alcoholic beverage with sugar, in the extract concentration of 5%, pointed in the sensorial preference// acceptability.

Water pollution has become an environmental catastrophe due to the rapid urbanization. The treatment of dumping of waste chemicals in water bodies has contributed to the increase in pollution. In addition to the pollution caused by waste chemicals, faecal bacteria such as Escherichia, Staphylococcus, Pseudomonas etc., can cause serious health issues. Techniques such as filtration and chlorination provide clean water but are associated with disadvantages such as toxic by-products. Although clean water can be still obtained by these techniques, the development of resistance by microorganisms with such conventional treatments of antibiotics is inevitable and poses a new threat. Various researches have taken place in the past few decades to provide clean drinking water. Photocatalysis is considered to be a promising viable alternative for the existing methods to solve the menace of water pollution. It is an advanced oxidation process where the reactive oxygen species are generated by using nanomaterials that can cause degradation of chemicals and pathogens. Particularly, photocatalysis using semiconductors and their composites have been tested for their use in the destruction of contaminants. Several methods have been used in the synthesis of nanomaterials and the variations in their morphologies have resulted in different applications such as photocatalysis and electrocatalysis. Among all semiconductors, TiO2 has been widely used in this application owing to their non-toxicity and abundance in availability. However, TiO2 can be activated only in the presence of UV light. Therefore, the formation of heterojunctions, doping of metals/no- metals in TiO2 has enabled the activation of TiO2 in the visible region. The former approach has also been studied with ceria and silver salts combination. Besides conventional metal oxides, other transitional metal oxides such as copper oxide and bismuth oxide have also been studied owing to its conducting property and facile growth on substrates respectively for enhanced photocatalysis. All the above tweaking has enabled efficient charge separation, band gap reduction, and prevention of recombination. In this thesis, all the nanomaterials and their composites have been synthesized using simple methods such as solution combustion, hydrothermal, solution co-precipitation, and chemical deposition. The primary aim of this thesis is to synthesize various effective nanomaterials with different morphologies, bandgap engineered nanocomposites, metal or non-metal doped metal oxides for efficient waste water treatment of dyes, antibiotics, phenols, and bacteria. Besides, relying on photocatalytic ability, the photoconductivity and intrinsic conducting properties of nanomaterials were exploited to perform photoelectrocatalysis that enhances the rate of decontamination to several orders than photocatalysis. In addition to focusing on increasing the rate of degradation, the main drawback of photocatalysis which is catalyst retrieval has been overcome using conducting substrates and nanomaterial coated substrates for efficient photocatalytic and photoelectrocatalytic decontamination of waste water. All the structural, morphological, chemical and optical properties were thoroughly studied using various characterization techniques such as XRD, SEM, TEM, XPS, UV-DRS, PL respectively. The rate kinetics of dye, antibiotic and phenol degradation was examined. Experimental data was tested with the proposed model in the case of photoelectrocatalytic degradation. The photocatalysts were also studied for its reusability for many cycles. All the proposed works have analyzed the reason for the enhanced activity by performing scavenger reactions to determine the responsible reactive oxygen species. Thus, this thesis exhibits a thorough understanding of how to design and engineer nanomaterials for photocatalytic and photoelectrocatalytic water remediation. The following are the chapters discussed in this thesis. Chapter 1 discusses the drawbacks associated with the current waste water treatment methods and the possibilities of photocatalysis to replace the existing treatments. The advantages of certain transition metals, conventional methods of synthesis and various other properties of the nanomaterials have been discussed. Chapter 2 explains the synthesis of TiO2 nanobelts using combustion synthesized TiO2 under UV and solar irradiation. The catalyst has been characterized for its structural, morphological, chemical and optical properties. The degradation of anionic and cationic dyes and their activity against E.coli bacteria have been evaluated. The efficiency of this catalyst has been compared with commercial Degussa P25. This study shows the morphological influence of nanomaterials on photocatalytic activity. Chapter 3 describes the synthesis of Ag3PO4 impregnated combustion synthesized TiO2 nanobelts using co-precipitation technique. The activity of this material has been studied under solar light. The catalyst has been characterized for its structural, morphological, chemical and optical properties. Similar to the previous chapter, the degradation of dyes and the antibacterial activity of this catalyst has been compared with commercial Degussa P25. This study explains the importance of morphology and charge carrier facilitation in the case of heterojunction formation. Chapter 4 explains the synthesis of ceria nanoflakes by solution combustion method using ascorbic acid as fuel and PEG assisted sonochemical method. The catalyst has been characterized for its structural, morphological, chemical and optical properties. The effect of silver salts such as AgBr on ceria/Ag3PO4 under visible region for degradation of dyes and antibacterial activity has been evaluated. This work elucidates the effect of band engineering in the charge carrier dynamics between interfaces of components within the catalysts. Chapter 5 elucidates the synthesis of vanadium, nitrogen co doped TiO2 catalysts for the simultaneous degradation of microbes and antibiotics. The primary aim of this work is to understand whether interstitial or substituted doped nitrogen will be effective in the presence of vanadium. The photoactivity of this novel catalyst was studied for its synergistic degradation of antibiotics and bacteria simultaneously towards the prevention of microbial resistance towards antibiotics. Chloramphenicol and E.coli were subjected to photodegradation under visible light. Chapter 6 explains the synthesis of copper oxide based nanomaterial for antibiotic and bacterial degradation by photoelectrocatalysis. In order to enhance the rate of photodegradation, photocatalysis has been upgraded with the application of a potential to photocatalytic systems that possess better charge conducting capability. Highly network like copper oxide has been synthesized using conventional combustion synthesis method and compared with copper oxide nanorods synthesized by hydrothermal method. The rate kinetics of photocatalytic and photoelectrocatalytic degradation of antibiotics has been examined thoroughly and validated based on a cyclic network model. This work demonstrates the synergistic rate enhancing capacity upon combining photocatalysis and electrocatalysis. Chapter 7 discusses the fabrication of Cu/CuO/FTO (fluorine doped tin oxide) based substrates for bacterial degradation. Considering the difficulties in photocatalyst retrieval processes and realizing the importance of electrocatalysis, conducting substrates such as Cu strip, FTO were subjected to antibacterial treatment. Formation of copper oxide onto copper strip during the course of reaction forced us to develop CuO/Cu and CuO/FTO interfaces to examine the photocatalytic and photoelectrocatalytic killing of E.coli. Chapter 8 investigates the fabrication of Bi2O3/Ag based material for photocatalytic and photoelectrocatalytic degradation for phenols and substituted phenols. This work starts with fabrication of Bi2O3 working electrodes by chemical deposition. Photodegradation experiments were conducted under UV irradiation and enhancement of the rate of degradation was observed when the working electrode was deposited with silver nanoparticles via chemical reduction method. Formation of the intermediate Bi(OH)x on Bi2O3 or Bi2O3/Ag has resulted in better hydroxyl radical generation upon excitation. Similarly, surface plasmon resonance due to silver nanoparticles was found to be responsible for augmentation in degradation efficiency of phenol. Chapter 9 briefly summarizes the work and provides future directions. The research work thus attempts to design and engineer photocatalytic nanomaterials that are better than the existing materials and emphasizes the importance towards water remediation.

Comme dans la plupart des maladies auto-immunes une prédominance féminine est observée dans la polyarthrite rhumatoïde (PR). Le chromosome X, présent en 2 exemplaires chez la femme, est intéressant puisque beaucoup de gènes à fonctions immunitaires y sont localisés. Dans ce travail, nous montrons que certains de ces gènes peuvent augmenter leur nombre de copies quand l'individu vieillit. En outre, cette variation est spécifique au sexe avec une augmentation chez les hommes et l'inverse chez les femmes. D’autre part, alors que généralement les femmes inactivent aléatoirement (50:50) le chromosome X d’origine maternel ou X d’origine paternel, nous montrons un biais d’inactivation (≥ 80:20) chez les femmes atteintes de PR. De plus ce biais est préférentiellement associé à celles qui portent les gènes de susceptibilité à la maladie. Ces résultats soulignent l’importance du chromosome X dans le développement de l’auto-immunité et aident à la compréhension du biais féminin dans ces maladies. / As in many autoimmune diseases, a female predominance is observed in rheumatoid arthritis (RA). The X chromosome, present in 2 copies in females, is of particular interest as it contains many genes with immune functions. In this work, we show an increase with age in copy number of some X-linked genes in peripheral blood cells of men, healthy or with RA. Importantly, this increase is not observed in women. On the other hand, when in fact females generally randomly inactivate (50:50) either the paternally-derived or the maternally-derived X chromosome, we show a skewed inactivation (≥ 80:20) in women with RA. Moreover this skewing correlates preferentially with women carrying disease susceptibility genes. Altogether, our findings highlight the importance of this fascinating chromosome in the development of autoimmunity in a step forward to better understand female predilection to autoimmune diseases.

L’accroissement de la population humaine, l’agriculture intensive et le développement industriel créent une pollution de l’air qui aujourd’hui devient préoccupante pour notre santé et notre environnement. Si la qualité de l’air extérieur fait l’objet depuis plusieurs décennies de règlementations qui permettent aujourd’hui de constater une diminution globale de la pollution dans les grandes agglomérations européennes, la pollution de l’air intérieur a quant à elle été longtemps sous-estimée. En effet, avec le développement de matériaux composites pour la construction et l’ameublement, la gamme de polluants de l’air intérieur s’est très largement agrandie et les concentrations ont globalement augmenté. Plusieurs études ont ainsi montré que de nombreux composés organiques volatils étaient détectés dans l’air intérieur à des concentrations bien plus élevées qu’à l’extérieur. D’autre part, la modification des modes de vie sédentaires et citadines ont pour conséquence une augmentation du temps passé dans des espaces confinés comme les logements, les lieux de travail et les transports en commun. Le simple renouvellement de l’air intérieur par de l’air extérieur devenant de moins en moins satisfaisant dans les grandes agglomérations, de nouvelles méthodes de traitement sont actuellement développées pour diminuer les concentrations de ces polluants tout en limitant la consommation d’énergie. La photocatalyse, en tant que procédé d’oxydation avancé fait partie des technologies intéressantes pour minéraliser des composés organiques volatils (COV). Après un rapide rappel du contexte sociétal de la pollution atmosphérique, les conditions de mesures et les méthodes possibles pour le traitement de cette pollution sont présentées. Le chapitre suivant regroupe les résultats sur le développement de matériaux photocatalytiques innovants et la mesure de leur efficacité. La première partie de ce chapitre fait le bilan des réacteurs photocatalytiques adaptés à l’étude de réactions à l’interface solide-gaz et résume les nombreuses difficultés liées à l’évaluation des performances de divers matériaux dans des conditions le plus souvent difficilement comparables. Dans la seconde partie, un premier matériau composite constitué de film polymère et de dioxyde de titane a été caractérisé par sa capacité à oxyder un composé volatil, le diméthyle disulfure, utilisé en agriculture pour la fumigation. Le développement d’un second matériau photocatalytique original, constitué de fibres de TiO2 pur a, quant à lui, été caractérisé par sa capacité à minéraliser des COV représentatifs de la pollution de l’air intérieur (acétone, heptane, toluène). Les deux dernières parties de ce chapitre se situent à l’interface entre la photochimie et la biologie. Dans un premier temps, la capacité d’inactivation bactérienne d’un textile « intelligent » sur lequel sont fixées des particules de dioxyde de titane couplées à un photosensibilisateur a été étudiée et l’efficacité sous rayonnement visible de ce tissu original a été analysée. L’impact de la pollution de l’air intérieur sur des cellules de la peau fait l’objet de la dernière partie de ce chapitre. Pour cela un montage permettant d’exposer des cellules de kératinocytes en culture, mais également des biopsies de peau humaine, à des concentrations contrôlées en COV a été mis au point. Nous avons ainsi pu mettre en évidence une réponse cellulaire à ce stress environnemental et préciser l’origine de ce stress. Enfin ce travail se termine par une ouverture sur des projets de recherche actuellement en cours ayant pour objet la mesure des espèces réactives de l’oxygène impliquées dans les réactions photochimiques et le développement de nouveau matériaux hybrides polymère/photosensibilisateurs. Des idées de projets à l’interface de la photochimie et de la biologie ouvrent de nouvelles perspectives à la suite de ces premiers résultats. / The increase of human population, the modern agriculture and industrial development generate air pollution, which is nowadays worrying for health and environment. Since several decades, outdoor air pollution has been regulated giving rise a global decrease of pollution in the most important European cities. However indoor air pollution was neglected for a long time. Indeed with development of composite materials for building and furnishing, the number of air pollutants strongly increased together with their concentrations. Several studies have thus demonstrated that numerous volatile organic compounds (VOC) were detected indoor at much higher concentration than outdoor. Moreover, due to the modification of sedentary and urban lifestyles, the time spent in confined spaces like housing, working places and public transportation increases. It is less and less satisfactory to simply renew indoor air with outdoor air in most of urban agglomerations. Accordingly, new processes for air treatment are developed in order to decrease indoor air pollutant concentrations while limiting energetic consumption. Photocatalysis is an advanced oxidation process potentially interesting for VOC removal. After a short reminder on the societal context of atmospheric pollution, measurement and treatment methods are presented in chapters I and II. The following chapter gathers the results obtained on the development of new photocatalytic materials and on the measure of their efficiency. The first part of this chapter is devoted to an overview of photocatalytic reactors for gas solid reactions and summarizes the numerous problems arising from the comparison of different materials under various conditions, which are not always similar. In the second part, a composite material made of titanium dioxide encapsulated in a polymer film is characterized and used for the oxidation of a volatile compound used for agricultural fumigation, dimethyl disulfide. The spectroscopic analysis led to the optimization of the material as a function of its thickness and its titanium dioxide loading. A second innovative photocatalytic material made of pure TiO2 fibers is characterized by its mineralization ability of representative indoor air VOC (acetone, heptane, and toluene). The performance of this material is compared to that of a commercial one, Quartzel ® made of TiO2 deposited on quartz fibers, under strictly identical conditions. The two last parts of this chapter are at the interface between photochemistry and biology. In a first strep, bacterial inactivation by a smart textile where titanium dioxide particles coupled with a photosensitizer is studded under visible light. In the last part, the impact of indoor air pollution on skin cells is presented. A dedicated device allowing keratinocytes culture cells and skin biopsies exposures to controlled VOC concentrations is developed. It is thus possible to evidence and to determine the origin of the cellular response to this environmental stress. At last, new research projects for a near future are then presented. They concern the determination of reactive oxygen species involved in photochemical reactions and the development of new hybrid polymers encapsulating photosensitizing molecules. Prospective ideas at the interface of photochemistry and biology conclude this memory.

Le cortex moteur primaire (M1) est souvent endommagé lors des lésions cérébrales telles que les accidents vasculaires cérébraux. Ceci entraîne des déficits moteurs tels qu'une perte de contrôle des membres controlatéraux. La récupération des lésions M1 s'accompagne d'une réorganisation hémodynamique dans les zones motrices intactes des deux hémisphères. Cette réorganisation est plus prononcée dans les premiers jours et semaines qui suivent la lésion. Toutefois, nous avons une compréhension limitée de la réorganisation neuronale rapide qui se produit dans ce réseau moteur cortical complexe. Ces changements neuronaux nous informent sur l’évolution possible de la plasticité subaiguë impliquée dans la récupération motrice. Par conséquent il était grand temps qu’une caractérisation de la réorganisation rapide de l'activité neuronale dans les régions motrices des deux hémisphères soit entreprise. Dans cette thèse nous avons exploré l'impact d'une lésion corticale localisée, unilatérale et réversible dans M1 sur l'activité neuronale des zones motrices des hémisphères ipsi et contralésionnel lorsque des primates non humains ont effectués des mouvements d’atteinte et de saisie. Notre modèle d'inactivation nous a permis d'enregistrer en continu des neurones isolés avant et après l'apparition des déficits moteurs. Dans une première étude, la réorganisation rapide qui se produit dans le cortex prémoteur ventral (PMv) des deux hémisphères a été étudiée (Chapitre 2). Le PMv est une zone connue pour être impliquée dans le contrôle moteur de la main et la récupération des lésions M1. Dans une seconde étude, la réorganisation rapide du M1 contralésionnel (cM1) a été étudiée et comparée à celles se produisant dans les PMv bilatérales (Chapitre 3). Le cM1 joue un rôle complexe dans la récupération des mouvements de précision de la main suite à une blessure à son homologue. Nous révélons une réorganisation neuronale importante et beaucoup plus complexe que prévu dans les deux hémisphères lors de l’apparition initiale des déficiences motrices. Nos données démontrent que les changements neuronaux survenant quelques minutes après une lésion cérébrale sont hétérogènes à la fois dans et entre les zones du réseau moteur cortical. Ils se produisent dans les deux hémisphères lors des mouvements des bras parétiques et non parétiques, et ils varient au cours des différentes phases du mouvement. Ces découvertes constituent une première étape nécessaire pour démêler les corrélats neuronaux complexes de la réorganisation au travers du réseau moteur des deux hémisphères à la suite d’une lésion cérébrale. / After brain injuries such as stroke, the primary motor cortex (M1) is often damaged leading to motor deficits that include a loss of fine motor skills of the contralateral limbs. Recovery from M1 lesions is accompanied by hemodynamic reorganization in motor areas distal to the site of injury in both hemispheres that are most pronounced early after injury. However, we have limited understanding of the rapid neuronal reorganization that occurs in this complex and distributed cortical motor network. As these neural changes reflect the landscape on which subacute plasticity involved in motor recovery will take place, an exploration of the rapid reorganization in neural activity that occurs in motor regions of both hemispheres is long overdue. In the current thesis, we set out to explore the impact of a localized, unilateral and reversible cortical injury to the M1 hand area on neuronal activity in motor-related areas of both the ipsi and contralesional hemispheres as non-human primates performed a reach and grasp task. Our inactivation model allowed us to continuously record isolated neurons before and after the onset of motor deficits. In a first study, the rapid reorganization taking place in the ventral premotor cortex (PMv) of both hemispheres was investigated (Chapter 2). The PMv is an area well-known to be critically involved in hand motor control and recovery from M1 lesions. In a second study, the rapid reorganization taking place in the contralesional M1 (cM1) was studied and compared to those occurring in bilateral PMv (Chapter 3). The cM1 has a complex role in recovery of dexterous hand movements following injury to its homologue. We reveal extensive, and much more complex than expected, neuronal reorganization in both hemispheres at the very onset of motor impairments. Our data demonstrate that neuronal changes occurring within minutes after brain injury are heterogenous both within and across areas of the cortical motor network. They occur in the two hemispheres during movements of both the paretic and non-paretic arms, and they vary during different phases of movement. These findings constitute a first step in a much needed and timely effort to unravel the complex neuronal correlates of the reorganization that takes place across the distributed motor network after brain injury.