Avec l'évolution des technologies et le développement des objets connectés, la consommation des circuits est devenue un sujet important. Dans cette thèse nous nous concentrons sur la consommation des mémoires non volatiles à piégeage de charge. Afin de diminuer la consommation, différentes architectures ont vu le jour comme les mémoires 2T ou Split Gate. Nous proposons deux nouvelles architectures de mémoires permettant la diminution de la consommation par rapport à une mémoire Flash standard. La première, appelée ATW (Asymmetrical Tunnel Window), est composée d'une marche d'oxyde au niveau de son oxyde tunnel qui lui permet d'être moins consommatrice qu'une mémoire Flash standard. Une seconde architecture mémoire appelée eSTM (embedded Select Trench Memory) est aussi présentée. Son principal atout est la présence de son transistor de sélection qui est indispensable pour avoir une faible consommation. Grâce à son architecture, cette cellule est bien meilleure que l'architecture proposée précédemment (ATW). Une dernière étude a été réalisée afin d'optimiser le procédé de fabrication de la mémoire eSTM pour le rendre plus robuste. / With the evolution of technologies and the development of connected objects, the circuit consumption is becoming an important subject. In this thesis, we focus on the consumption of trap-charge non-volatile memories. To decrease the consumption, different architectures have emerged, like 2T or Split Gate memories. We propose two new memory architectures allowing to decrease the consumption compared to the standard Flash memory. The first, called ATW (Asymmetrical Tunnel Window), is composed of an oxide step in the tunnel oxide which allows to be less consumer than a standard Flash memory. A second memory architecture called eSTM (embedded Select Trench Memory) is also presented. Its main advantage is its select transistor which is essential to obtain a lower consumption. Thanks to its architecture, this cell is better than the previously proposed architecture (ATW). The last study has been performed to optimize the process flow of the eSTM memory to make it more robust.

Neste trabalho objetivou-se estudar o comportamento de acasalamento de Cyrtomon luridus Boheman (Coleoptera: Curculionidae), bem como a presença de semioquímicos mediando o acasalamento e a interação com a planta hospedeira Duboisia sp. (Solanaceae). Machos e fêmeas adultos recém-emergidos foram coletados no campo e levados para o laboratório. Incialmente foi determinado o melhor parâmetro morfológico para diferenciação de machos e fêmeas. Verificou-se que machos deste curculionídeo possuem a abertura genital oclusa pelo último tergito. O comportamento de acasalamento foi observado em casais virgens durante nove dias. Verificou-se que machos e fêmeas de C. luridus atingiram a maturidade sexual dois dias após a emergência. Machos e fêmeas realizaram acasalamentos repetidos com o mesmo parceiro em qualquer horário do dia. O comportamento de acasalamento deste curculionídeo foi dividido nas fases pré-copulatória, copulatória e pós-copulatória. Além disso, estudos de olfatometria revelaram que machos e fêmeas de C. luridus foram fortemente atraídos por voláteis de machos se alimentando sobre a planta hospedeira. A coleta e análise destes voláteis revelaram a presença dos compostos (Z)-3-hexenal, hexanal, (E)-2-hexenal, (E)-2-hexen-1-ol, fenilacetaldeido, linalol e geraniol, como eletrofisiologicamente ativos. O presente trabalho traz importantes informações sobre o comportamento de acasalamento e ecologia química de Entiminae e servirão de base para estudos com outras espécies desta importante subfamília de Curculionidae. / This work aimed to study the mating behavior of Cyrtomon luridus Boheman (Coleoptera: Curculionidae), as well as the presence of semiochemicals mediating the mating and the interaction of the insects with the host plant, Duboisia sp. (Solanaceae). Newly emerged males and females adults were collected in the field and taken to the laboratory. Initially it determined the best morphological parameter to differentiate males and females. It was found that males possess the genital opening occluded by the last tergite. The mating behavior was observed in virgin couples for nine days. It was found that males and females C. luridus reached sexual maturity two days after emergence. Males and females made repeated matings with the same partner at any time of day. The mating behavior was clearly divided into the pre-copulatory, copulatory, and post-copulatory phases. In addition, olfatometrics studies revealed that males and females C. luridus were strongly attracted to volatile males feeding on the host plant. The collection and analysis of these volatiles revealed the compounds (Z)-3-hexenal, hexanal, (E)-2-hexenal, (E)-2-hexen-1-ol, phenylacetaldehyde, linalool and geraniol as being eletrophysiologically. The present work brings important information about the mating behavior and chemical ecology of Entiminae, which will serve as support for studies with other species of this important subfamily of Curculionidae.

Apesar da importância dos herbívoros de solo na estruturação da comunidade e também como pragas agrícolas, nosso entendimento sobre a ecologia química de suas interações com a planta hospedeira é limitado comparado à vasta literatura sobre os herbívoros que se alimentam de órgãos aéreos das plantas. O presente estudo teve como objetivo identificar os estímulos olfativos envolvidos na busca hospedeira de Diabrotica speciosa. Larvas de 1º. ínstar de D. speciosa foram capazes de localizar plantas hospedeiras de milho, mas sem distinguir plantas não induzidas das induzidas pela herbivoria radicular e/ou foliar. Já larvas de 2º e 3º ínstar apresentaram preferência por plantas sem indução frente a plantas induzidas pela herbivoria radicular. No entanto, estas larvas preferiram plantas induzidas pela herbivoria foliar em detrimento a plantas sem indução. Na situação em que plantas sem indução foram confrontadas com plantas induzidas pela herbivoria foliar + radicular não houve preferência destas larvas. A análise do perfil de voláteis juntamente com o PCA (\'Análise dos Componentes Principais\') revelaram semelhança entre os voláteis emitidos por plantas induzidas pela herbivoria radicular e foliar + radicular, bem como entre plantas sem indução e induzidas pela herbivoria foliar. Estas diferenças nos perfis de voláteis não foram suficientes para explicar o comportamento de busca hospedeira de larvas de 2º e 3º ínstar, sugerindo a possibilidade de outras pistas químicas associadas com a busca hospedeira de larvas de D. speciosa. / Despite the importance of soil herbivores in community structure and their status as pests, our understanding about the chemical ecology of their interactions is still limited compared to the vast literature on aboveground herbivores. The current study aimed at identifying the olfactory stimuli used in host search by Diabrotica speciosa. First-instar larvae of D. speciosa were able to find corn host plants; however, they did not distinguish between herbivore-induced and non-induced plants (control). Second-and-third-instar larvae preferred non-induced over root-herbivore induced plants. Nevertheless, second-and-third-instar larvae preferred leaf-herbivore induced plants, inflicted by D. speciosa adults, over non-induced plants. When larvae were exposed to non-induced and leaf + root-herbivore induced plants, they did not show preference. Volatile profile analysis together with PCA (Principal Component Analysis) revealed similarity between volatiles emitted by root-herbivore induced and leaf + root-herbivore induced plants as well as between non-induced and leaf-herbivore induced plants. These differences in plant volatile profile were not sufficient to explain host search behavior of second-and-third instar larvae, suggesting the possibility of other chemical cues are associated with host search of D. speciosa larvae.

Em resposta aos danos ocasionados por insetos, as plantas emitem voláteis que atraem os inimigos naturais desses herbívoros. Embora essa relação tritrófica venha sendo intensamente estudada, muitos mecanismos envolvidos nesta interação ainda permanecem inexplorados. Dentre os compostos voláteis induzidos por herbivoria e emitidos pelas plantas, os terpenos são os mais expressivos e abundantes. Em resposta ao dano ocasionado por um inseto, cascatas bioquímicas são iniciadas na planta, as quais podem alterar a expressão de genes envolvidos na resposta a tal dano. Este trabalho analisou as mudanças na expressão gênica e produção de compostos voláteis em plantas de milho, Zea mays (Poaceae)promovidas por lagartas Spodoptera frugiperda (Lepidoptera: Noctuidae) ao longo do tempo. Utilizando a técnica de PCR em tempo real (qRTPCR) foram verificadas respostas no nível da expressão gênica das plantas submetidas à indução por herbivoria. Foram analisados os genes de uma lipoxigenase e de três terpeno sintases, enzimas envolvidas na produção de compostos voláteis que atraem parasitóides de S. frugiperda. As plantas submetidas à herbivoria apresentaram níveis de expressão gênica e emissão de voláteis maiores do que as plantas sadias. Os resultados fornecem bases para o entendimento dos mecanismos endógenos responsáveis pela liberação de voláteis nas plantas visando o estabelecimento de novos fundamentos para o controle biológico de pragas. / In response to insect damage, plants emit volatiles that attract natural enemies of herbivores. Although this tritrophic interaction has been intensively studied, many mechanisms involved in this interaction remain unexplored. Among the herbivore-induced volatile compounds, terpenes are the most abundant and significant ones. In response to insect damage, biochemical pathways are activated, which can alter the expression of genes involved in the response to that damage. This study examined changes in gene expression and volatile compounds production in maize plants, Zea mays (Poaceae) promoted by Spodoptera frugiperda (Lep.: Noctuidae) caterpillars through time. Using the real-time PCR technique (qRT-PCR) we verified responses on the level of gene expression of plants subjected to herbivores feeding. We analyzed genes of lipoxygenase and three terpene synthases, enzymes involved in the synthesis of volatile compounds that attract parasitoids of S. frugiperda. Plants subjected to herbivory had higher levels of gene expression and volatile emission when compared to healthy plants. Results provide basis for better understanding of plant volatile emission endogenous mechanisms in order to set new foundations for biological control of pests.

As rizobactérias promotoras de crescimento (PGPR) são microrganismos que ocorrem naturalmente no solo, são conhecidas por proporcionar melhorias no desenvolvimento das plantas atuando de diversas formas. Bacillus subtilis (cepa GB03) é uma PGPR disponível para comercialização como fungicida biológico concentrado, utilizada no tratamento de sementes de diversas culturas como algodão, soja, amendoim, trigo e cevada. Destaca-se pela capacidade de promover o crescimento de plantas por meio da emissão de voláteis. Vários estudos com Arabidopsis thaliana já comprovaram que B. subtilis (GB03) é capaz de auxiliar no desenvolvimento da planta por meio da promoção de crescimento e pela supressão de patógenos habitantes de solo. No entanto, o seu papel na proteção de plantas contra a herbivoria de insetos ainda não é bem caracterizado. Deste modo, buscou-se avaliar os efeitos da interação de B. subtilis (GB03) com plantas de rúcula (Eruca sativa) e Plutella xylostella (traça-das-crucíferas). Este inseto pertence à ordem Lepidoptera, considerado praga de maior importância no cultivo de Brassicaceae ao redor do mundo. Devido à sua alta prolificidade e capacidade de adaptação e ao seu curto ciclo de vida, tornou-se uma das pragas mais resistentes e de difícil controle da agricultura. Atualmente, os custos em escala mundial com o controle da praga anualmente chegam em torno de US $ 4 a 5 bilhões. Foram utilizados dois tratamentos, plantas inoculadas com B. subtilis (GB03) e controle (plantas não inoculadas). Avaliou-se o crescimento de plantas de rúcula e o peso seco de parte aérea. Para avaliar o desempenho e dano de P. xylostella em ambos tratamentos, previamente foram pesados grupos de quinze lagartas e submetidas a alimentação de plantas de rúcula durante 24 horas. Posteriormente, as lagartas foram retiradas e pesadas novamente e a área foliar consumida foi calculada por meio do software editor de imagens ImageJ®. A preferência de oviposição do inseto foi testada por meio de olfatometria, composta apenas de pistas olfativas e em arenas contendo tanto pistas olfativas quanto visuais. A emissão de voláteis foi caracterizada quantitativamente e qualitativamente por cromatografia gasosa e analisada por espectrometria de massas. A inoculação com GB03 em plantas de rúcula promoveu melhor crescimento das plantas em relação ao tratamento controle, ao mesmo tempo em que diminuiu os danos pelo consumo alimentar do inseto na planta. P. xylostella não apresentou distinção entre os odores das plantas nos testes de olfatometria. Entretanto, observou-se menor número de ovos em plantas com GB03 nos bioensaios de arena. Não foram constatadas diferenças significativas na emissão total de voláteis entre os tratamentos com e sem GB03, no entanto, foram encontradas concentrações diferentes dos compostos (Z)-3-hexenol e 2-ethyl-1-decanol. Outros testes devem ser realizados com a finalidade de estabelecer o papel desempenhado por GB03 na indução de defesas de plantas contra insetos. / The plant growth promoting rhizobateria (PGPR) are microorganisms that naturaly live in the soil, known by improving the plants\' development in many ways. Bacillus subtilis (strain GB03) is a comercial available PGPR, sold as a concentrated biological fungicide, applied in seed treatment of different cultures as cotton, soybean, peanut, wheat and barley. Moreover, it stands out by its capacity of plant growth promoting via volatiles emission. Several studies with Arabidopsis thaliana showed that B. subtilis (GB03) can help the plant development via growth promotion and by soil pathogens supression. However, its role in plant protection against insect herbivory has not been characterized yet. Thus, it aimed to evaluate the interaction effects among B. subtilis (GB03), arugula plants (Eruca sativa) and Plutella xylostella (Diamondback moth). This insect belongs to the order Lepidoptera and have been considered the main pest in Brassicaceae fields around the world. Due to its high prolificacy and plasticity in field survival, and its short life cycle, it has become one of the most resistant and hard control pest in agriculture. Currently, the annualy world costs with this pest control is about US $ 4-5 bilions. Here, it was used two treatments, innoculated plants with B. subtilis (GB03) and control (non-innoculated plants). The arugula plants growth and dry mass of shoots were evaluated. To analyze the performance and damage by P. xylostella in both treatments, it was previously weighed groups with fifteen caterpillars and submitted to feeding on arugula plants during 24 hours. After that, the caterpillars were removed and weighed again and the consumed leaf area was calculated by the image editor software ImageJ®. The insect oviposition preference was tested by olfactometry, with only olfactory cues and in arenas containing both, olfactory and visual cues. Volatiles emission was quantitatively and qualitatively characterized by gas chromatography and analyzed by mass spectrometry. GB03 innoculation in arugula plants promoted a better growth when compared to control, and, at the same time, there was an increasing in the plant damage by insect food consumption. P. xylostella did not show distinction between odors of the plants in olfactometry tests. Although, it was observed less number of eggs in plants with GB03 in arena bioassays. It was not found significant differences in total volatile emission between the treatments with and without GB03, even though different concentrations of (Z)-3-hexenol and 2-ethyl-1-decanol were observed. Other tests must be performed in order to estabilish the role played by GB03 in plant induction defense against insects.

Made available in DSpace on 2017-07-21T18:53:20Z (GMT). No. of bitstreams: 1 Cintia Maia Braga.pdf: 853677 bytes, checksum: 4107ff87848d02112262f112adeb1c1b (MD5) Previous issue date: 2013-02-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Apple fermented beverages are produced in Brazil with low commercial quality fruits that do not pass by rating the degree of maturation. An study becomes necessary to determine the aromatic profile of the products processed apples in different stages of maturation knowing that this can change the technological and sensory quality of the product. Thus the aim of this study was to identify and determine the differences between apple juices and apple fermented beverage elaborated with fruits from different varieties and ripening stages in the aroma profile. Analysis of fruit ripeness, preparation of products under different conditions, flavor profile, physico-chemical composition and statistical analysis for verification and determination of the differences between the juice and fermented were perfomed. The physical chemical characteristics attested the raw material ripening of the samples. The sugar content of juices and alcohol content of fermented in general increased with ripening increasing, the opposite of the evolution of acids that in most of the samples decreased with increasing ripening, as happened with the nitrogen content. Ripening stage significantly influenced the aroma composition of apple juice and apple fermented beverages. Esters, aldehydes, acids, alcohols and ketones were identified in all samples by gas chromatographic (GC), however at higher concentrations in samples of fermented mainly made of senescent apples. Regarding the juices, ripe Gala had a prominence relating to aroma concentration over other cultivars. Using a chemometric approach by principal components analysis (PCA) and hierarchical cluster analysis (HCA) were verified that fermented have a higher composition of ten volatile compounds avaliated and fewer concentration of just one compound than apple juices. In this way chemometric approach with GC techniques can be suitable parameters to differentiate apple juice and apple fermented by aroma profiles. / Fermentados de maçãs são produzidos no Brasil com frutas de baixa qualidade comercial que não passam por classificação quanto ao grau de maturação. Sabe-se que isto pode alterar a qualidade tecnológica e sensorial do produto tornando necessário um estudo para determinação do perfil aromático dos produtos processados com maçãs em diferentes estádios de maturação. O objetivo deste estudo foi identificar e determinar as diferenças de perfil aromático entre sucos e fermentados de maçã elaborados com frutas de diferentes cultivares e estádios de maturação. Para isto foram realizadas análises para determinação do estádio de maturação da fruta, determinação do perfil aromático, composição físico-química e análise estatística para verificação e determinação das diferenças entre os sucos e fermentados. O teor de açúcar dos sucos e de álcool dos fermentados em geral aumentaram com o amadurecimento, o oposto da evolução dos ácidos que, na maioria das amostras decresceu com o amadurecimento, tal como aconteceu com o teor de nitrogênio. O estádio de maturação influenciou significativamente a composição aromática de suco e fermentado de maçã. Ésteres, aldeídos, ácidos, álcoois e cetonas foram identificados em todas as amostras por cromatografia gasosa (GC), porém em concentrações mais elevadas em amostras de fermentado, principalmente a partir de maçãs senescentes. Em relação aos sucos, Gala madura teve um destaque com relação à concentração de aromas sobre outras cultivares. Através de uma abordagem quimiométrica por análise de componentes principais (PCA) e análise de agrupamento hierárquico (HCA) foi verificado que os fermentados tem uma maior concentração de dez dos compostos voláteis avaliados e menos concentração de apenas um composto em relação ao suco de maçã. Desta forma abordagem quimiométrica com técnicas de GC podem ser parâmetros adequados para diferenciar suco e fermentado de maçã por perfil aromático.

La consommation énergétique est devenue un défi majeur dans les domaines de l'informatique embarquée et haute performance. Différentes approches ont été étudiées pour résoudre ce problème, entre autres, la gestion du système pendant son exécution, les systèmes multicœurs hétérogènes et la gestion de la consommation au niveau des périphériques. Cette étude cible les technologies de mémoire par le biais de mémoires non volatiles (NVMs) émergentes, qui présentent intrinsèquement une consommation statique quasi nulle. Cela permet de réduire la consommation énergétique statique, qui tend à devenir dominante dans les systèmes modernes. L'utilisation des NVMs dans la hiérarchie de la mémoire se fait cependant au prix d'opérations d'écriture coûteuses en termes de latence et d'énergie. Dans un premier temps, nous proposons une approche de compilation pour atténuer l'impact des opérations d'écriture lors de l'intégration de STT-RAM dans la mémoire cache. Une optimisation qui vise à réduire le nombre d'opérations d'écritures est implémentée en utilisant LLVM afin de réduire ce qu'on appelle les silent stores, c'est-à-dire les instances d'instructions d'écriture qui écrivent dans un emplacement mémoire une valeur qui s'y trouve déjà. Dans un second temps, nous proposons une approche qui s'appuie sur l'analyse des programmes pour estimer des pire temps d'exécution partiaux, dénommés δ-WCET. À partir de l'analyse des programmes, δ-WCETs sont déterminés et utilisés pour allouer en toute sécurité des données aux bancs de mémoire NVM avec des temps de rétention des données variables. L'analyse δ-WCET calcule le WCET entre deux endroits quelconques dans un programme, comme entre deux blocs de base ou deux instructions. Ensuite, les pires durées de vie des variables peuvent être déterminées et utilisées pour décider l'affectation des variables aux bancs de mémoire les plus appropriées. / Traditional memories such as SRAM, DRAM and Flash have faced during the last years, critical challenges related to what modern computing systems required: high performance, high storage density and low power. As the number of CMOS transistors is increasing, the leakage power consumption becomes a critical issue for energy-efficient systems. SRAM and DRAM consume too much energy and have low density and Flash memories have a limited write endurance. Therefore, these technologies can no longer ensure the needs in both embedded and high-performance computing domains. The future memory systems must respect the energy and performance requirements. Since Non Volatile Memories (NVMs) appeared, many studies have shown prominent features where such technologies can be a potential replacement of the conventional memories used on-chip and off-chip. NVMs have important qualities in storage density, scalability, leakage power, access performance and write endurance. Nevertheless, there are still some critical drawbacks of these new technologies. The main drawback is the cost of write operations in terms of latency and energy consumption. We propose a compiler-level optimization that reduces the number of write operations by elimination the execution of redundant stores, called silent stores. A store is silent if it’s writing in a memory address the same value that is already stored at this address. The LLVM-based optimization eliminates the identified silent stores in a program by not executing them. Furthermore, the cost of a write operation is highly dependent on the used NVM and its non-volatility called retention time; when the retention time is high then the latency and the energetic cost of a write operation are considerably high and vice versa. Based on that, we propose an approach applicable in a multi- bank NVM where each bank is designed with a specific retention time. We analysis a program and we compute the worst-case lifetime of a store instruction to allocate data to the most appropriate NVM bank.

Le regain d'attention des industriels pour les mémoires non volatiles intégrant des nanocristaux, illustré par l'introduction sur le marché de la Flexmemory de Freescale en technologie 90 nm, incite à poursuivre des études sur ce type de systèmes. Pour cela, nous avons mis au point des cellules mémoires élémentaires, à savoir des transistors MOS dont l'oxyde de grille contient une grille granulaire formée par un plan de nanocristaux de silicium (Si-ncx) stockant la charge électrique.Ce travail présente les principaux résultats issus de ces travaux, ceux-ci allant du procédé de fabrication à la caractérisation fine des dispositifs mémoires. Le parfait contrôle de l'élaboration de la grille granulaire de Si-ncx par implantation ionique à très basse énergie (ULE-IBS) est accompagné de caractéristiques « mémoires » répondant aux normes industrielles d'endurance et d'une discrimination des pièges responsables du chargement. Le stockage majoritaire par les Si-ncx est démontré, ce qui est essentiel pour la rétention de la charge. Nous avons développé une technique électrique permettant d'extraire à la fois la quantité de charge stockée par les Si-ncx mais également leurs principales caractéristiques structurales (taille, densité, position dans l'oxyde). Cette extension de la technique électrique de « pompage de charges », non destructive et in-situ permet de suivre l'état du composant en fonctionnement et de caractériser des pièges (e.g. les Si-ncx) pour la première fois au-delà de 3 nm de profondeur dans l'oxyde. Ces résultats ont été validés par des observations TEM. La résolution du pompage de charge étant le piège unique, nous avons alors couplé l'ULE-IBS avec la lithographie « Stencil » pour réduire latéralement le nombre de Si-ncx synthétisés. Cette technique nous permet pour le moment de contrôler la synthèse locale à la position désirée dans l'oxyde de « poches » de Si-ncx de 400 nm. La synthèse de « quelques » Si-ncx est envisagée à très court terme. Nous serons alors en mesure de fabriquer des mémoires à nombre choisi de nanocristaux (par SM-ULE-IBS), dont les propriétés structurales (taille, densité, position) et électriques (quantité de charge stockée) seront vérifiées par pompage de charge, offrant ainsi des outils puissants pour la fabrication et la caractérisation de mémoires à nombre réduit de nanocristaux, notamment pour des longueurs de grilles inférieures à 90 nm / The aim of this thesis has been to fabricate and electrically characterize elementary memory cells containing silicon nanocrystals (Si-ncs), in other words MOSFET which insulating layer (SiO2) contains a Si-ncs array storing the electrical charge. We have shown that we perfectly control the synthesis of a 2D array of 3-4 nm Si-ncs embedded into the MOSFET oxide by low-energy ion implantation (1-3 keV) Reaching this goal implied two key steps: on the one hand develop a reliable MOSFET fabrication process incorporating the Si-ncs synthesis steps and on the other hand develop tools and methods for both memory window and Si-ncs array itself characterizations. We have developed an in-situ characterization technique based on the well-known charge pumping technique, allowing for the first time the extraction of traps depth (e.g. the Si-ncs array) further than 3 nm into the oxide layer leading to the characterization of both position of these Si-ncs into the SiO2 matrix and their structural properties (diameter, density). These results have been confirmed by EF-TEM measurements. Finally, we have worked on the improvement of controlled local synthesis of Si-ncs pockets by combining low-energy ion implantation and stencil lithography. We reduced the size of these pockets down to about 400 nm using this parallel, low cost and reliable technique and identified the limiting effect for the pockets size reduction. These results pave the way for memory cells containing a few Si-ncs with a well-defined position into the oxide and a well-controlled number of ncs

L’hydroperoxyde lyase (HPL) est une enzyme issue de la voie de la lipoxygénase, voie métabolique très représentée chez les végétaux, impliquée dans la production de composés aromatisants (l’hexanal, le 3Z-hexenal et le 2E-hexenal). Ces composés sont responsables de l’odeur fraîche de l’herbe coupée dite « note verte » et sont très utilisés par les industries cosmétiques et agroalimentaires. Leur biosynthèse résulte de l’oxydation des acides gras polyinsaturés en hydroperoxydes par la lipoxygénase, puis de leur clivage par l’hydroperoxyde lyase (HPL). Les procédés actuels de production de ces composés présentent certains inconvénients, ils sont notamment très polluants et peu performants, aussi l’utilisation d’enzymes recombinantes dans de tels procédés permettrait d’obtenir ces molécules de manière plus efficace tout en bénéficiant du label "naturel". L’ADNc codant pour l’hydroperoxyde lyase (HPLwt) a été isolé au laboratoire à partir d’olives noires. Afin d’améliorer la solubilité de l’enzyme, une HPL dépourvue de son peptide de transit chloroplastique (HPLdel) a également été produite. Les deux enzymes ont été exprimées chez E.coli, purifiées par chromatographie d’affinité puis caractérisées biochimiquement. Elles agissent exclusivement sur les 13-hydroperoxydes (13-HPL) à un pH et une température optimum de 7,5 et 25°C. De plus l’évaluation des paramètres cinétiques de l’enzyme montre qu’elles ont une meilleure efficacité catalytique (kcat/Km) sur les 13-hydroperoxydes d’acide linolénique (3,68 s-1.µM-1) que sur les 13-hydroperoxydes d’acide linoléique (0,54 s-1.µM-1). La bioconversion des 13-hydroperoxydes d’acide linoléique et linolénique en hexanal et 3Z-hexénal par l’action de l’HPLwt et l’HPLdel a été étudiée. Des taux de conversion maximum atteignant 93 % et 68 % pour la production d’hexanal et 73 % et 45% pour la production d’3Z-hexénal ont été obtenus quand l’HPLwt et l’HPLdel sont utilisées respectivement. La stabilité de l’enzyme a ensuite été étudiée. Des essais de conservation montrent que l’utilisation de glycérol à 10% (v/v) permet le maintien de la totalité de l’activité de l’HPLwt et de l’HPLdel durant cinq semaines de stockage à -80°C. De plus, l’ajout de composés chimiques tels que le KCl, le NaCl, le Na2SO4, la glycine et le glycérol permettent d’augmenter l’activité enzymatique des deux enzymes et d’améliorer les conditions de synthèse de l’hexanal et du 3Z-hexénal en diminuant la quantité d’enzyme nécessaire à leur production. / The hydroperoxide lyase (HPL) derives from a metabolic pathway named lipoxygenase pathway widely represented in plants and involved in the production of flavoring compounds (hexanal, 3Z-hexenal and 2E-hexenal). These volatile compounds are responsible for the fresh odor of cut grass known as "green note" and have a particularly interest for flavor and food industries. Their biosynthesis results from the oxygenation of linoleic and linolenic acids by lipoxygenase action to form fatty acid hydroperoxides, then of their cleavage by hydroperoxide lyase action. The processes of production currently used are highly polluting or lead to a low yield. To overcome these drawbacks, the use of recombinant enzymes in such processes constitutes an attractive alternative because they would allow producing these molecules in a more effective way, while benefiting from the "natural" label.A cDNA encoding for HPL (HPLwt) from black olive fruit was isolated, and in order to improve the enzyme solubility, the HPL deleted of its chloroplast transit peptide (HPLdel) was then produced. Both enzymes were expressed into E. coli (M15), purified by affinity chromatography, and characterized. They act exclusively on 13-hydroperoxide (13-HPL) and display an optimum pH at 7.5 and an optimum temperature at 25 °C. The bioconversion of 13-hydroperoxides of linoleic and linolenic acids in hexanal and 3Z-hexenal respectively, using HPLwt or HPLdel was studied. Conversion yields reach a maximum of 93 % and 68 % for hexanal production, and 73 % and 45 % for 3Z-hexenal when reactions were performed by HPLwt and HPLdel respectively.The enzyme stability was then studied. Conservations tests using 10 % glycerol (v/v) allows the maintenance of the entire activity of HPLwt and HPLdel during five weeks of storage at -80°C. Furthermore, the addition of chemical compounds such as KCl, NaCl, Na2SO4, glycine, and glycerol can increase the efficiency of both enzymes and improve the synthesis of hexanal and 3Z-hexenal by decreasing the amount of enzyme required to produce them.

Trois magmas (haplotonalite synthétique, basalte et dacite de Santorin) ont été juxtaposés et déformés à l’aide d’une presse de type Paterson pour contraindre les conditions de mélange de magmas à haute pression (300 MPa). Ces trois magmas ont été utilisés en conditions sèches ou hydratées et dans une gamme de température comprise entre 600 et 1200°C, permettant d’obtenir plusieurs fractions cristallines et contrastes de viscosité. Les textures de mélange produites lors des expériences dépendent de la fraction cristalline et sont similaires aux textures rencontrées dans la nature. Les textures de mélange mécanique (mingling) produites sont la ségrégation de cristaux depuis leur magma source, la formation d’enclaves par détachement et de filaments par étirement de parcelles de magma. Le mélange chimique (mixing) est illustré par des zones d’interactions comportant une large variété de liquides intermédiaires et la cristallisation de nouvelles phases. Le mélange est produit en l’absence d’une charpente cristalline dans l’un ou l’autre des magmas, si le contraste de viscosité est faible (< 0,3 unité log) et en dessous d’un seuil de viscosité absolue, déterminé entre 107 et 108 Pa.s. Par ailleurs, l’eau joue un rôle important sur les propriétés rhéologiques des magmas, et donc sur leurs capacités de mélanges : elle abaisse le seuil de mélange de près de 200°C entre des magmas saturés en eau, et son exsolution (présence de bulles) entraîne une réduction significative des viscosités promouvant le mélange à des fractions cristallines plus faibles. Les conditions rhéologiques favorables aux mélanges entre le magma d’un réservoir et un magma plus chaud qui le recharge ont été déterminées selon la fraction de magma injecté. Cette fraction est de 0,5 minimum pour la majorité des réservoirs typiques du contexte d’arc. La comparaison avec des systèmes plutoniques et volcaniques exposant des figures de mélange montre que les conditions favorables aux mélanges sont atteintes avec des fractions inférieures. Ceci suggère que le fonctionnement d’un réservoir magmatique est influencé par ses styles et taux de recharge, ainsi que la quantité de volatils. / Three magmas (a synthetic haplotonalite, a basalt and a dacite from Santorini Volcano) have been deformed together at P=300 MPa in a Paterson type apparatus to constrain the mixing capacities between chemically contrasted magmas. Both dry and hydrous conditions were investigated at temperatures varying between 600 and 1200°C to vary magma crystallinity and visc osity contrasts. Mingling and mixing features were produced, which closely resemble those encountered in nature. Mingling features are xenocrysts, enclaves, and melt filaments. Diverse intermediate liquids and newly grown crystals characterize the mixing textures. Both mixing and mingling features were produced after crystal network breakage, at low viscosity contrasts (less than 0.3 log unit) and bulk viscosities lower than 107 – 108 Pa.s. The presence of water considerably affects the rheological properties of magmas and their mixing capacities: water-saturated magmas are able to mix at temperatures 200°C colder than their dry equivalent, and bubbles may influence the viscosity contrast leading to mixing at lower crystal fractions. Rheological conditions favourable to magma mixing between the resident magma in the reservoir and a hot replenishing one were determined according to the injected mafic magma fraction. The minimum fraction of mafic magma for mixing is 0.5 for typical arc magma chambers. The comparison with plutonic and volcanic rocks displaying mixing features shows that mixing may, however, occur at lower fractions. This suggests that reservoir dynamism may depend on the style and the frequency of the injection rate, and the amount of volatiles.