Depuis 1995 et la première proposition de remplacer la grille flottante en polysilicium des mémoires non volatiles (MNV) par des nanocristaux de Si (nc-Si), la recherche est très active dans ce domaine. Cette étude se propose d'une part, d'améliorer les caractéristiques d'une MNV à nanocristaux en termes de temps de rétention et d'autre part, d'évaluer les possibilités d'un stockage multibits dans ces nanocristaux. De ce point de vue, le semiconducteur InAs présente des avantages par rapport au Si. En effet, l'InAs possède un offset de bande de conduction plus important que le Si avec l'oxyde SiO2, ce qui devrait conduire à un meilleur confinement des électrons et donc à un meilleur temps de rétention qu'avec le Si. Par ailleurs, la masse effective des porteurs dans l'InAs étant plus faible que celle dans le Si, les niveaux confinés sont mieux séparés, ce qui augmenterait les potentialités de stockage multibits avec des électrons. L'objectif de ma thèse a consisté à évaluer le potentiel d'une MNV à nanocristaux d'InAs (nc-InAs) par comparaison aux MNV à nc-Si. Dans un premier temps, il s'est agi de faire croître, dans un réacteur d'épitaxie par jets moléculaires, des nc-InAs sur un oxyde tunnel SiO2 formé sur un substrat Si. Les nanocristaux sont monocristallins et hémisphériques. Il s'est avéré que la température de croissance joue un rôle prépondérant dans le contrôle de la densité des nc-InAs alors que leur taille (de 2 à 10 nm de hauteur) dépend plutôt de la quantité de matière déposée. Leur densité peut atteindre 7 x 10^11 cm^(-2). Dans un deuxième temps, nous avons fabriqué des structures Métal-Oxyde-Semiconducteur (MOS) à nc-InAs destinées à intégrer des cellules mémoires. Nous avons montré qu'il était possible de charger et de décharger les structures à nc-InAs. Les temps d'écriture et effacement peuvent atteindre 1 us et 0,1 ms respectivement à 12 V et 11 V. Par ailleurs, les mesures des temps de rétention ont démontré que l'utilisation des nc-InAs permet d'augmenter le temps de rétention de 2 décades par rapport aux nc-Si pour une structure de dimensions identiques. Il s'avère que l'amélioration des caractéristiques de rétention des électrons dans les nc-InAs est due à l'offset de bande plus important de l'InAs avec le SiO2 que Si. En conclusion, la maîtrise de la croissance et de l'encapsulation des nc-InAs a permis leur intégration dans des dispositifs mémoires tests qui ont présenté des caractéristiques prometteuses pour les mémoires non volatiles.

Flowering plants display remarkable phenotypic diversity, especially in reproductive structures, much of which is thought to be associated with pollination by animals. Pollination syndromes are collections of floral traits (e.g. flower colour, shape, odour) that are associated with a plant attracting particular functional groups of animal pollinators. We explored the extent to which traits associated with the moth pollination syndrome translated into pollination by moths in the Pacific coast dune endemic Abronia umbellata and found mixed results: in one year of study, there was no difference in seed set by day- vs. night-pollinated inflorescences, but in another year of study, night-pollinated inflorescences set significantly more seed than those pollinated during the day. We integrate this work with tests of pollen and resource limitation of seed production and with seed set surveys of natural populations to address proximate and ultimate causes of low seed set, finding low rates of pollinator visitation, high pollen limitation of seed production in all populations studied, and no evidence of endogenous resource limitation of seed production. We propose that “excess” flowers may be functionally male, serving to increase outcross siring success. The transition from self-incompatibility and obligate outcrossing to self-compatibility and predominant selfing is the most common evolutionary transition among the flowering plants and traits associated with outcrossing may become reduced across such shifts, potentially through the action of natural selection, especially if pollinators are also herbivores, or if the signals that pollinators use to locate flowers are also used by herbivores. We examined the reduction of attractive visual and olfactory floral traits in A. umbellata across a shift from outcrossing to selfing and found a reduction of all floral traits considered. We found that floral volatile emissions were reduced more strongly than flower size or floral display (number of flowers per inflorescence), but there was no evidence of an ecological cost associated with conspicuousness: we did not find reduced leaf herbivory among selfers relative to outcrossers. / Thesis (Master, Biology) -- Queen's University, 2012-08-30 19:46:23.663

Made available in DSpace on 2015-04-17T14:55:20Z (GMT). No. of bitstreams: 1 Arquivototal.pdf: 3846399 bytes, checksum: ab31b9a3c4617a2b39ee0a454b0d1a71 (MD5) Previous issue date: 2012-06-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Bees are the main pollinators in terrestrial environments. Plants are sessile organisms that only attain cross-sexual reproduction through the activity of pollen vectors. As such, flowers offer hints for the interspecific encounter; they obtain pollination services and in exchange, usually, they provide floral resources to pollinators. The main resource sought by bees is pollen, which is used as larval nourishment. From the plants standpoint, however, there must be a balance between the offered resource and the amount of pollen grains effectively transferred to the stigmas. Such balance is dictated by a number of variables; pollinator attractivity, pollinator effectiveness, quantity of pollen exported/received and the energy allotted in the reproductive process. Aware of this paradox and observing that flowers exhibit specific traits associated with certain groups of pollinators (floral syndromes), there has been a tendency among researchers to evaluate flower evolution as if it were directed towards specialization. Nonetheless, specialization is associated to the referential group and behaves within a continuum of plain generalization and high specialization. I have studied two groups of bees: one a specialist and the other a generalist, although adapted to a rare niche among bees the nocturnal habit. I studied specialized bees of the genus Protodiscelis (Colletidae, Neopasiphaeinae), a group that exhibits feeding habit specialization, and their interaction with flowers. Protodiscelis bees are oligolectic, meaning that they are genetically determined to collect pollen grains for larval provisioning among phylogenetically constraint plant taxa. These bees will only gather pollen from species of the family Alismataceae, a group comprised of aquatic herbs common to lentic ecosystems. I investigated the pollination of four species belonging to this family and aimed to understand the plant-pollinator interactions within a spatial and morphofunctional frame, which also involves the floral cues used by the bees in order to find they preferred host flowers. I divided the obtained results into three upcoming publications, each dealing with one of the analyzed themes. The pollination of Echinodorus palaefolius was studied in several flooded areas in the Caatinga. Additionally I investigated the relationships between bees and flowers of five other species of the same genus (E. subalatus, E. glandulosus, E. paniculatus, E. pubescens e Echinodorus sp.). Echinodorus palaefolius is self-incompatible and relied on pollinators to develop fruits. The phenology of the species is dictated by the rain regime and flowers were visited by three bee species alone: Protodiscelis alismatis, Apis mellifera and Trigona spinipes. Surprisingly, the morphologically generalist flowers of this plant species are visited by an oligolectic bee (P. alismatis) and by the two among the most generalist of bees (A. mellifera and T. spinipes). The oligolectic species, however, was accounted with over 80% of flower visits. Bees of P. alismatis exhibit clear behavioral and morphological adaptations, such as extremely plumose setae that can hold the small pollen grains of Echinodorus. They were present in 96% of the 41 flooded areas that I sampled in the Caatinga. Bees of P. alismatis were also the main pollinators of the other species of Echinodorus collected within over 1,000 km of natural distribution of the Caatinga. The specialized relationship of these bees with their host plants is highly consistent in the insular environments of the Caatinga, where the aquatic Alismataceae naturally occur. The pollination ecology of three species of a neotropical clade limnocharitaceae (Alismataceae) was studied among distinct populations in northeast Brazil and middle-west Brazil. The results of pollination ecology were compared to those of H. martii, previously studied. I researched the morphological attributes and the aspects of the reproductive system that differentiate these species. Limnocharis flava, L. laforestii and Hydrocleys nymphoides were all visited by Protodiscelis palpalis, the same oligolectic species previously recognized as the sole effective pollinator of H. martii. Flowers of L. flava were found to be morphologically and functionally similar to those of H. martii. In both species, the presence of staminodes protect the pollen and bees of P. palpalis alone were effective pollinators, due to an adapted behavior that allows them to access the pollen chamber. The flowers of L. laforestii, on the other hand, were effectively pollinated by other species of bees, regardless of the presence of staminodes. But in this case, no protective pollen chamber is formed. In the population of the municipality of Serra Negra do Norte, P. palpalis was replaced by a yet undescribed species of Protodiscelis. For Limnocharis, however, animal pollen vectors are not required for fruit development and both studied species yielded high seed counts through autogamy. The flowers of H. nymphoides are larger and bear staminodes that do promote filtering of other bee species. Regardless of genetic self-incompatibility, H. nymphoides is pollinated by several generalist bee species, notably the social T. spinipes, A. mellifera and Bombus brevivilus (Apidae). Knowing that autogamy is one of the main variables for the establishment and dissemination of plants in biological invasions (Baker s Law), the occurrence of this type of pollination may largely explain the invasive status of the three studied species in Asia, Oceania and North America. The generalist association with pollinators would explain the invasions observed for H. nymphoides. I used the sampling method of dynamic headspace and gas chromatography coupled to mass spectrometry (GC-MS) to describe the volatile compounds emitted by the flowers of H. martii and H. nymphoides. I tested the attractivity of the main isolated compounds to bees of Protodiscelis palpalis in field conditions. Floral scents in the family Alismataceae were described for the first time. Flowers of H. martii produced a bouquet comprised of 22 compounds, whereas the bouquet of H. nymphoides contained 13 compounds. Each species, despite sharing several compounds, present a characteristic floral scent profile. Methoxylated benzenoids were the main constituents of the bouquets of H. martii and H. nymphoides. ρ-Methylanisole is the main compound in the floral scent of H. martii and 3,4-dimethoxytoluene the main compound in H. nymphoides. These two compounds, however, were isolated in both species. ρ-methylanisole, 2-methoxy-4-methylphenol, 3,4-dimethoxytoluene, 3,4,5-trimethoxytoluene and methyl salicylate were used in field biotests with artificial flowers assembled from yellow and blue adhesive paper. Only ρ-methylanisole yielded significantly more approaches from bees towards artificial flowers of both colors in comparison to control flowers. Artificial yellow flowers, however, proportionally attracted more bees than blue flowers. Ours results, the first ever obtained in a natural environment setting, show that a single volatile compound attracts female P. palpalis and is the most important communication channel between these pollinators and flowers of H. martii e H. nymphoides. Our results reinforce the fact that specific volatile compounds present in flower bouquets might be crucial for the localization of host plants by oligoletic bees. Bees of Megalopta (Halictidae, Augochlorini) are nocturnal and explore a niche that is mostly inaccessible to other bees. In the interaction between Megalopta bees and their host plants I studied one of the signals emitted by the flowers: floral scents. Scents have long been known as pollinator attractants, but little is known about the identity of the compounds produced by flowers and which among them incite behavioral responses of animals, such as pollinator attraction. I selected volatile compounds commonly isolated in floral scents and conducted field attraction biotests with Megalopta bees. I tackled the hypotheses that such common floral scent compounds, frequently identified in night-blooming angiosperms, would be involved in the attraction of Megalopta bees. I found out that single aromatic compounds effectively attracted female bees and elicited visiting behavior. Bees were significantly more attracted to traps baited with benzyl acetate, benzyl benzoate and methyl salicylate than to unbaited traps or traps baited with compounds less frequently isolated in night-blooming flowers (β-ionone, eucalyptol, eugenol and vanillin). I concluded that Megalopta bees use scents to find flowers under low-light conditions, as observed by several other groups of nocturnal pollinators. Moreover, I provided a new sampling technique for these rarely collected insects. / Abelhas são os principais polinizadores das plantas com flores. Plantas são sésseis e a reprodução sexuada cruzada somente ocorre através de vetores de pólen. Sendo assim, flores zoofílicas provêm pistas para o encontro interespecífico, são polinizadas e fornecem recursos florais aos polinizadores. O principal recurso coletado por abelhas herbívoros Apiformes é pólen, o principal alimento larval. Para as plantas, entretanto, existe um balanço entre recurso fornecido e quantidade de grãos de pólen efetivamente transportados para os estigmas. Esse balanço é regido por variáveis, entre elas a atratividade ao polinizador, a sua efetividade na polinização, a quantidade de pólen exportado e recebido e a quantidade de energia dispensada no processo reprodutivo. Considerando que flores apresentam atributos específicos para determinados grupos de polinizadores (síndromes florais), houve uma tendência entre os estudiosos da polinização de avaliar a evolução de flores como dirigida à especialização. Entretanto, a especialização é relativa ao grupo observado e se comporta dentro de um continuum entre amplamente generalista e altamente especialista. Estudei dois grupos de abelhas, um que apresenta especialização em pólen e outro generalista em relação aos recursos polínicos, mas ocupando um nicho raro entre abelhas, o hábito noturno. Estudei abelhas especializadas de Protodiscelis (Colletidae, Neopasiphaeinae) e sua interação com flores. Protodiscelis é um grupo de abelhas oligoléticas, ou seja coletam grãos de pólen para as larvas em flores do mesmo gênero ou família. As fêmeas coletam grãos de pólen exclusivamente em flores de Alismataceae, grupo formado por espécies aquáticas comuns a ambientes lênticos. Foi estudada a polinização de quatro espécies dessa família procurando entender a interação no âmbito espacial, morfofuncional e das pistas florais usadas pelas abelhas para encontrar as flores das quais dependem. Dividi os resultados obtidos em três manuscritos, cada um tratando de um dos temas analisados. A polinização de Echinodorus palaefolius foi estudada em vários alagados da caatinga. Adicionalmente, verifiquei as relações entre abelhas e flores de cinco outras espécies do mesmo gênero (E. subalatus, E. glandulosus, E. paniculatus, E. pubescens e Echinodorus sp.). Echinodorus palaefolius é autoincompatível e depende de polinizadores para a formação de frutos. Sua fenologia foi regida pelas chuvas e suas flores foram visitadas somente por três espécies de abelhas: Protodiscelis alismatis, Apis mellifera e Trigona spinipes. Surpreendentemente, as flores morfologicamente generalistas dessa espécie de planta, são visitadas por uma espécie oligolética (P. alismatis) e por duas das espécies de abelhas entre as mais generalistas conhecidas (A. mellifera e T. spnipes). A espécie oligolética, no entanto, foi responsável por mais de 80% das visitas às flores. Essa espécie de abelha tem comportamento e adaptações morfológicas claras, tais como pelos extremamente plumosos capazes de coletar os grãos de pólen pequenos de Echinodorus. Foram presentes em 96% dos 41 alagados que amostrei na caatinga. Abelhas de P. alismatis também foram os principais polinizadores das outras espécies de Echinodorus coletadas ao longo de mais de 1000 km da distribuição natural da caatinga. A relação especializada dessa espécie com suas plantas hospedeiras é muito consistente no ambiente insular na caatinga onde essas plantas aquáticas ocorrem. A polinização de Limnocharis flava, L. laforestii e Hydrocleys nymphoides, espécies do clado neotropical limnocharitaceas da família Alismataceae em várias populações no nordeste e centro-oeste brasileiro foram estudadas. Os resultados foram comparados com as características da associação entre H. martii e Protodiscelis palpalis, estudada anteriormente. VI Analisei os atributos morfológicos e o sistema reprodutivo que diferenciam essas espécies. As três espécies foram visitadas por Protodiscelis palpalis, mesma espécie oligolética e único polinizador efetivo de H. martii. Flores de L. flava foram morfo-funcionalmente semelhantes às de H. martii. Nessas duas espécies a presença de estaminódios protegem o pólen e somente P. palpalis, que apresenta comportamento adaptado para acessar a câmara de pólen, polinizou efetivamente as flores. Já nas flores de L. laforestii apesar da presença de estaminódios, abelhas de outras espécies polinizam as flores. Na população de Serra Negra do Norte, P. palpalis foi substituída por outra espécie de Protodiscelis ainda não descrita. Em Limnocharis, entretanto, não há necessidade de visitas para a formação de frutos. As duas espécies formaram sementes em grande quantidade por autogamia. As flores de H. nymphoides são maiores e os estaminódios mais curtos. Essa espécie autoincompatível é polinizada por várias espécies de abelhas generalistas principalmente sociais de T. spinipes, A. mellifera e Bombus brevivillus (Apidae). Visto que autogamia é uma das principais variáveis para estabelecimento e disseminação de plantas em invasões biológicas (Lei de Baker), a ocorrência desse tipo de polinização talvez possa explicar a condição de invasoras (na Ásia, Oceania e América do Norte) das três espécies estudadas. A relação generalista com polinizadores explicaria as invasões observadas para H. nymphoides. Utilizei as técnicas de headspace dinâmico e cromatografia gasosa acoplada à espectrometria de massa (GC-MS) para descrever os voláteis florais produzidos pelas flores de H. martii e H. nymphoides. Testei a atratividade dos principais compostos às abelhas de Protodiscelis palpalis em campo. Odores florais na família Alismataceae foram descritos pela primeira vez. As flores de H. martii produziram 22 compostos e H. nymphoides 13. Cada espécie, apesar de vários compostos em comum, tem seu perfil de odores característico. Benzenóides metoxilados foram os principais componentes dos buquês. ρ-metilanisol foi dominante em H. martii e 3,4-dimetoxitolueno em H. nymphoides. Os compostos florais ρ-metilanisol, 2-metoxi-4-metilfenol, 3,4-dimetoxitolueno, 3,4,5-trimetoxitolueno e salicilato de metila foram testados no campo em flores artificiais construídas com fita adesiva amarela e azul. Somente ρ-metilanisol atraiu significativamente mais abelhas à flores artificias das duas cores comparadas com as de controle. Flores amarelas atraíram proporcionalmente mais abelhas que azuis. Os nossos resultados, obtidos pela primeira vez para abelhas oligolétcas neotropicais e em ambiente natural, mostram que um único composto volátil atrai fêmeas de P. palpalis demonstrando que é o canal de comunicação mais importante entre P. palpalis e as flores de H. martii e H. nymphoides. Nossos resultados reforçam que os compostos voláteis específicos do buquê de flores são cruciais para a localização de plantas hospedeiras pelas abelhas oligolécticas. Abelhas de Megalopta (Halictidae, Augochlorini) são noturnas e exploram um nicho inacessível à outras abelhas. Nessa interação estudei os odores como sinal floral fornecido pelas flores. Odores há muito são conhecidos como atrativo de polinizadores, entretanto, pouco se sabe em relação à identidade dos compostos produzidos e que estimulam respostas comportamentais, tais como atração nos polinizadores. Selecionei odores comuns a buquês florais de plantas e os testei no campo na atratividade de abelhas Megalopta. Testei a hipótese de que odores florais comuns, amplamente produzidos por flores de antese noturna, seriam capazes de atrair abelhas de Megalopta. Encontrei que compostos aromáticos isolados foram capazes de atrair essas abelhas e eliciaram um comportamento de visita. As abelhas foram significativamente mais atraídas às armadilhas com acetato de benzila, benzoato de benzila e salicilato de metila como iscas do que outros compostos menos comuns em flores de antese noturna. Abelhas de Megalopta, dessa maneira, usam odores para encontrar flores nas condições de baixa luminosidade, tal como vários outros grupos de polinizadores noturnos.

Avec la diminution du nœud de la technologie CMOS, la puissance statique et dynamique augmente spectaculairement. It est devenu l'un des principaux problèmes en raison de l'augmentation du courant de fuite et de la longue distance entre les mémoires et les circuits logiques. Au cours des dernières décennies, les dispositifs de spintronique, tels que la jonction tunnel magnétique (JTM) écrit par transfert de spin, sont largement étudiés pour résoudre le problème de la puissance statique grâce à leur non-volatilité. L'architecture logic-in-memory (LIM) hybride permet de fabriquer les dispositifs de spintronique au-dessus des circuits CMOS, réduisant le temps de transfert et la puissance dynamique. Cette thèse vise à la conception de circuits logiques et mémoires pour le système de faible puissance, en combinant les technologies JTM et CMOS. En utilisant un modèle compact JTM et le design-kit CMOS de STMicroelectronics, nous étudions les circuits hybrides MTJ/CMOS de 1-bit et multi-bit, y compris les opérations de lecture et d'écriture. Les méthodes d'optimisation sont également introduites pour améliorer la fiabilité, ce qui est extrêmement important pour les circuits logiques où les blocs de correction d'erreur ne peuvent pas être facilement intégrés sans sacrifier leurs performances ou augmenter la surface de circuit. Nous étendons la structure MTJ/CMOS hybride de multi-bit à la conception d’une mémoire MRAM avec les circuits périphériques simples. Basés sur le concept de LIM, les circuits logiques/arithmétiques non-volatiles sont conçus. Les JTMs sont intégrés non seulement comme des éléments de stockage, mais aussi comme des opérandes logiques. Tout d'abord, nous concevons et analysons théoriquement les portes logiques non-volatiles (PLNVs) comprenant NOT, AND, OR et XOR. Ensuite, les additionneurs complets non-volatiles (ACNVs) de 1-bit et 8-bit sont proposés et comparés avec l'additionneur classique basé sur la technologie CMOS. Nous étudions l'effet de la taille de transistor CMOS et des paramètres de JMT sur les performances d’ACNV. De plus, nous optimisons l’ACNV sous deux faces. Premièrement, un circuit de détection (mode de tension) de très haute fiabilité est proposé. Après, nous proposons de remplacer le JTM à deux électrodes par un JTM à trois électrodes (écrit par transfert de spin assisté par l’effet Hall de spin) en raison du temps d'écriture et de la puissance plus petit. Basé sur les PLNVs et ACNVs, d'autres circuits logiques peuvent être construits, par exemple, soustracteur non-volatile. Enfin, une mémoire adressable par contenu non-volatile (MACNV) est proposée. Deux décodeurs magnétiques visent à sélectionner des lignes et à enregistrer la position de recherche dans un état non-volatile. / With the shrinking of CMOS (complementary metal oxide semi-conductor) technology, static and dynamic power increase dramatically and indeed has become one of the main challenges due to the increasing leakage current and long transfer distance between memory and logic chips. In the past decades, spintronics devices, such as spin transfer torque based magnetic tunnel junction (STT-MTJ), are widely investigated to overcome the static power issue thanks to their non-volatility. Hybrid logic-in-memory (LIM) architecture allows spintronics devices to be fabricated over the CMOS circuit plane, thereby reducing the transfer latency and the dynamic power dissipation. This thesis focuses on the design of hybrid MTJ/CMOS logic circuits and memories for low-power computing system.By using a compact MTJ model and the STMicroelectronics design kit for regular CMOS design, we investigate the hybrid MTJ/CMOS circuits for single-bit and multi-bit reading and writing. Optimization methods are also introduced to improve the reliability, which is extremely important for logic circuits where error correction blocks cannot be easily embedded without sacrificing their performances or adding extra area to the circuit. We extend the application of multi-context hybrid MTJ/CMOS structure to the memory design. Magnetic random access memory (MRAM) with simple peripheral circuits is designed.Based on the LIM concept, non-volatile logic/arithmetic circuits are designed to integrate MTJs not only as storage elements but also as logic operands. First, we design and theoretically analyze the non-volatile logic gates (NVLGs) including NOT, AND, OR and XOR. Then, 1-bit and 8-bit non-volatile full-adders (NVFAs), the basic elements for arithmetic operations, are proposed and compared with the traditional CMOS-based full-adder. The effect of CMOS transistor sizing and the MTJ parameters on the performances of NVFA is studied. Furthermore, we optimize the NVFA from two levels. From the structure-level, an ultra-high reliability voltage-mode sensing circuit is used to store the operand of NVFA. From the device-level, we propose 3-terminal MTJ switched by spin-Hall-assisted STT to replace the 2-terminal MTJ because of its smaller writing time and power consumption. Based on the NVLGs and NVFAs, other logic circuits can be built, for instance, non-volatile subtractor.Finally, non-volatile content addressable memory (NVCAM) is proposed. Two magnetic decoders aim at selecting a word line to be read or written and saving the corresponding search location in non-volatile state.

La thèse de Giovanni BETTI BENEVENTI portes sur la caractérisation électrique et la modélisationphysique de dispositifs de mémoire non-volatile à changement de phase. Cette thèse a été effectuée dans le cadre d’une cotutelle avec l’Università degli Studi di Modena e Reggio Emilia (Italie).Le manuscrit en anglais comporte quatre chapitres précédés d’une introduction et terminés par uneconclusion générale.Le premier chapitre présent un résumé concernant l’état de l’art des mémoires a changement de phase. Le deuxième chapitre est consacré aux résultats de caractérisation matériau et électrique obtenus sur déposition blanket et dispositifs de mémoire à changement de phase (PCM) basées sur le nouveau matériau GeTe dopé carbone (GeTeC).Le chapitre trois s’intéresse à l’implémentation et à la caractérisation expérimentale d’un setup demesure de bruit a basse fréquence sur dispositifs électroniques a deux terminaux développé auxlaboratoires de l’Università degli Studi di Modena e Reggio Emilia en Italie.Enfin, dans le dernier chapitre est présentée une analyse rigoureuse de l’effet d’auto-chauffage Joulesur la caractéristique I-V des mémoires a changement de phase intégrant le matériau dans la phase polycristalline. / Within this Ph.D. thesis work new topics in the field of Non-Volatile Memories technologies have been investigated, with special emphasis on the study of novel materials to be integrated in Phase-Change Memory (PCM) devices, namely:(a) Investigation of new phase-change materialsWe have fabricated PCM devices integrating a novel chalcogenide material: Carbon-doped GeTe (or simply, GeTeC). We have shown that C doping leads to very good data retention performances: PCM cells integrating GeTeC10% can guarantee a 10 years fail temperature of about 127°C, compared to the 85°C of GST. Furthermore, C doping reduces also fail time dispersion. Then our analysis has pointed out the reduction of both RESET current and power for increasing carbon content. In particular, GeTeC10% PCM devices yield about a 30% of RESET current reduction in comparison to GST and GeTe ones, corresponding to about 50% of RESET energy decrease.Then, resistance window and programming time of GeTeC devices are comparable to those of GST.(b) Advanced electrical characterization techniquesWe have implemented, characterized and modeled a measurement setup for low-frequency noise characterization on two-terminal semiconductor devices.(c) Modeling for comprehension of physical phenomenaWe have studied the impact of Self-induced Joule-Heating (SJH) effect on the I-V characteristics of fcc polycrystalline-GST-based PCM cells in the memory readout region. The investigation has been carried out by means of electrical characterization and electro-thermal simulations.

Les mémoires non-volatiles (MNV) sont l'objet d'un effort de recherche croissant du fait de leur capacité à limiter la consommation statique, qui obère habituellement la réduction des dimensions dans la technologie CMOS. Dans ce contexte, cette thèse aborde plus spécifiquement deux technologies de mémoires non volatiles : d'une part les jonctions tunnel ferroélectriques (JTF), dispositif non volatil émergent, et d'autre part les dispositifs à transfert de spin (TS) assisté par effet Hall de spin (EHS), approche alternative proposée récemment pour écrire les jonctions tunnel magnétiques (JTM). Mon objectif est de développer des modèles compacts pour ces deux technologies et d'explorer, par simulation, leur intégration dans les circuits non-volatiles.J'ai d'abord étudié les modèles physiques qui décrivent les comportements électriques des JTF : la résistance tunnel, la dynamique de la commutation ferroélectrique et leur comportement memristif. La précision de ces modèles physiques est validée par leur bonne adéquation avec les résultats expérimentaux. Afin de proposer un modèle compatible avec les simulateurs électriques standards, nous j'ai développé les modèles physiques mentionnés ci-dessus en langue Verilog-A, puis je les ai intégrés ensemble. Le modèle électrique que j'ai conçu peut être exploité sur la plate-forme Cadence (un outil standard pour la simulation de circuit). Il reproduit fidèlement les comportements de JTF. Ensuite, en utilisant ce modèle de JTF et le design-kit CMOS de STMicroelectronics, j'ai conçu et simulé trois types de circuits: i) une mémoire vive (RAM) basée sur les JTF, ii) deux systèmes neuromorphiques basés sur les JTF, l'un qui émule la règle d'apprentissage de la plasticité synaptique basée sur le décalage temporel des impulsions neuronale (STDP), l'autre mettant en œuvre l'apprentissage supervisé de fonctions logiques, iii) un bloc logique booléen basé sur les JTF, y compris la démonstration des fonctions logiques NAND et NOR. L'influence des paramètres de la JTF sur les performances de ces circuits a été analysée par simulation. Finalement, nous avons modélisé la dynamique de renversement de l'aimantation dans les dispositifs à anisotropie perpendiculaire à transfert de spin assisté par effet Hall de spin dans un JTM à trois terminaux. Dans ce schéma, deux courants d'écriture sont appliqués pour générer l'EHS et le TS. La simulation numérique basée sur l'équation de Landau-Lifshitz-Gilbert (LLG) démontre que le délai d'incubation de TS peut être éliminé par un fort EHS, conduisant à la commutation ultra-rapide de l'aimantation, sans pour autant requérir une augmentation excessive du TS. Nous avons appliqué cette nouvelle méthode d'écriture à la conception d'une bascule magnétique et d'un additionneur 1 bit magnétique. Les performances des circuits magnétiques assistés par l'EHS ont été comparés à ceux écrits par transfert de spin, par simulation et par une analyse fondée sur le modèle théorique. / Non-volatile memory (NVM) devices have been attracting intensive research interest since they promise to solve the increasing static power issue caused by CMOS technology scaling. This thesis focuses on two fields related to NVM: the one is the ferroelectric tunnel junction (FTJ), which is a recent emerging NVM device. The other is the spin-Hall-assisted spin-transfer torque (STT), which is a recent proposed write approach for the magnetic tunnel junction (MTJ). Our objective is to develop the compact models for these two technologies and to explore their application in the non-volatile circuits through simulation.First, we investigated physical models describing the electrical behaviors of the FTJ such as tunneling resistance, dynamic ferroelectric switching and memristive response. The accuracy of these physical models is validated by a good agreement with experimental results. In order to develop an electrical model available for the circuit simulation, we programmed the aforementioned physical models with Verilog-A language and integrated them together. The developed electrical model can run on Cadence platform (a standard circuit simulation tool) and faithfully reproduce the behaviors of the FTJ.Then, using the developed FTJ model and STMicroelectronics CMOS design kit, we designed and simulated three types of circuits: i) FTJ-based random access memory (FTRAM), ii) two FTJ-based neuromorphic systems, one of which emulates spike-timing dependent plasticity (STDP) learning rule, the other implements supervised learning of logic functions, iii) FTJ-based Boolean logic block, by which NAND and NOR logic are demonstrated. The influences of the FTJ parameters on the performance of these circuits were analyzed based on simulation results.Finally, we focused on the reversal of the perpendicular magnetization driven by spin-Hall-assisted STT in a three-terminal MTJ. In this scheme, two write currents are applied to generate spin-Hall effect (SHE) and STT. Numerical simulation based on Landau-Lifshitz-Gilbert (LLG) equation demonstrates that the incubation delay of the STT can be eliminated by the strong SHE, resulting in ultrafast magnetization switching without the need to strengthen the STT. We applied this novel write approach to the design of the magnetic flip-flop and full-adder. Performance comparison between the spin-Hall-assisted and the conventional STT magnetic circuits were discussed based on simulation results and theoretical models.

L’accident de Fukushima a montré que sous certaines conditions, un accident de fusion du cœur (jugé hautement improbable) peut survenir et engendrer des conséquences dramatiques en termes de rejets de produits radioactifs dans l’environnement. La mise en place d’adsorbants poreux type zéolithe dans les filtres d’éventage constitue une solution prometteuse afin de limiter la dissémination de produits radioactifs notamment les espèces iodées volatiles, vers l’environnement. Dans cette étude, nous avons cherché à évaluer dans quelle mesure les propriétés structurales et chimiques d’adsorbants poreux essentiellement des zéolithes à l’argent, pouvaient affecter leurs performances vis-à-vis de la rétention d’I2 et de CH3I. Dans ce but, nous avons mis en relation les données issues de la caractérisation des différentes formulations zéolithiques (DRX, ATR/IR, DRIFTS du CO adsorbé, MEB, MET, et DR-UV-Vis) avec les données recueillies lors des tests dynamiques d’adsorption en phase gazeuse (capacités d’adsorption, facteurs de décontamination, stabilité thermique du piégeage). Ensuite, le comportement des zéolithes dans des conditions plus représentatives d’un accident grave (hautes températures, présence d’inhibiteurs, irradiation…) a été étudié pour les adsorbants les plus intéressants. Nous avons également cherché à mieux élucider les mécanismes de piégeage en utilisant à la fois une approche expérimentale (spectroscopie in situ) et théorique (DFT). D’une manière générale, nous avons trouvé que les capacités d’adsorption pour CH3I dépendent surtout de la quantité des sites argent présents à l’état dispersé dans la charpente sous forme de cations Ag+ et de petits clusters, mais également de paramètres structuraux tels que la taille des pores. D’autre part, une méthodologie particulière a été développée afin de quantifier les différentes formes piégées et ainsi de mieux comprendre l’effet des paramètres structuraux sur la stabilité thermique du piégeage, notamment sous forme de précipités AgI. Il a été montré que la stabilité du piégeage est fortement influencée par le taux d’échange et par la nature de la structure zéolithique. La combinaison des techniques spectroscopiques in situ infrarouges et UV-Vis a été également utilisée dans le but d’élucider le mécanisme de piégeage de CH3I par les zéolithes à l’argent. D’une part, la réactivité des espèces d’argent ainsi que leur transformation en AgI a été suivie par DR-UV-Vis. D’autre part, les schémas réactionnels mettant en jeu la partie carbonée ont été établis en utilisant la spectroscopie IR à la fois en phase adsorbée (DRIFTS) et en phase gazeuse (FTIR). La formation des précipités AgI est initiée à 100°C par la dissociation de CH3I (partielle à cette température) sur les sites acides de Brönsted de la zéolithe et les sites argent. Ensuite, des espèces moléculaires AgI puis des clusters (AgI)n sont formés dans les supercages de la structure faujasite. En présence d’humidité ou à des températures plus élevées, certains précipités AgI peuvent former des entités plus larges sur la surface externe (phase AgI détectée en DRX après test). D’autre part, la décomposition thermique et catalytique des espèces méthoxy donne lieu à la formation de nombreux sous-produits (MeOH, MeOMe, alcanes, alcènes…). Parmi tous les adsorbants testés, les zéolithes échangées Ag/Y ont affiché les meilleures performances de rétention. Des résultats encourageants en présence d’inhibiteurs, sous irradiation et aux faibles concentrations ont été également obtenus pour les zéolithes faujasites argentées (type Y). L’ensemble des résultats obtenus permet d’envisager l’utilisation de certaines formulations dans une application nucléaire type accident grave, mais également de développer de nouvelles connaissances notamment en ce qui concerne d’autres nouveaux adsorbants (Metal Organic Framework MOF et silices mésoporeuses argentées ou fonctionnalisées) / A severe nuclear accident (as Fukushima) may induce dramatic consequences in terms of radiological releases into the environment. The combination of current filtration devices (such as aqueous scrubbers and sand bed filters) with an additional filtration stage made of inorganic porous adsorbent (zeolite) constitute a promising solution in order to avoid the release of radioactive iodine species. The present study aims to establish some correlations between chemical and structural parameters of porous adsorbents mainly silver-zeolites, on the one hand, and adsorption properties towards I2 and CH3I on the other hand. The role played by various zeolitic parameters was assessed by combining adsorption data in gaseous phase (adsorption capacity, decontamination factors, trapping stability) together with physico-chemical data obtained from characterization studies (XRD, ATR/IR, DRIFTS of adsorbed CO, SEM, TEM and DR-UV-Vis). Then, the effect of adsorption temperatures, potential inhibitors and irradiation was also discussed for the most interesting adsorbents in order to extrapolate to severe accidental conditions. The trapping mechanism was also investigated using in-situ spectroscopic accessories as well as theoretical calculations by DFT. It was shown that CH3I adsorption capacities are mainly dependent on the amount of silver that could be deposited in dispersed form (as Ag+, and small clusters) within the internal framework, as well as structural parameters such as pore size. On the other hand, a specific methodology was applied in order to quantify the different forms of stored iodine and therefore to better assess the influence of structural parameters on the trapping thermal stability. It was found that the trapping stability is mainly dependent on silver exchange level and on the nature of zeolitic structure. For the first time, the combination of several spectroscopic techniques was also implemented. On the one hand, in situ Diffuse Reflectance UV-Vis Spectroscopy (DRS-UV-Vis) was employed in order to monitor the evolution of silver species during exposure to gaseous methyl iodide. On the other hand, the time- and temperature-evolution of organic species was investigated using in situ Diffuse Reflectance Infrared Fourier Transformed Spectroscopy (DRIFTS) combined with gas-phase reactor measurements. The first step is the dissociation of some CH3I molecules, which is catalyzed by the acidic and silver sites of the zeolite. The dissociated I is then captured by silver to form molecular and clustered AgI entities within the zeolite supercages, which can coalesce and sinter on the external surface upon prolonged exposure to humidity to form silver iodide precipitates (detected by XRD). On the other hand, the carbonaceous part of the CH3I molecules undergo successive catalytic transformations at medium temperatures with zeolite active sites, to yield different by-products (MeOH, DME, higher alkanes, alkenes…). Among all the investigated sorbents for iodine species retention, Ag/Y zeolites have displayed the best retention performances. Promising results were also found in the presence of inhibitors, under irradiation and for low concentrations. The obtained results allow to consider using some of the tested formulations for a nuclear severe accident application, but also to give insights about the behavior of other new adsorbents (Metal Organic Framework MOF and silver-impregnated or functionalized mesoporous silica)

Body odour perception plays an important role in human mate choice, especially in women. It was previously proposed that women select partners whose body odour resembles that of woman's fathers. Yet, this phenomenon has only been confirmed using ethological studies based on subjective perception of body odour similarities. Therefore, the aim of my diploma thesis was to test this hypothesis instrumentally using comprehensive GC×GC-TOFMS and subsequent multidimensional analyses of body odour chemical profiles of male partners and fathers of adult women. Body odour sampling from left and right axilla of fathers and partners of 41 women (altogether 164 samples) was performed using cotton swabs, which were then frozen and extracted into hexane. Typical human volatile substances, such as hydrocarbons, carboxylic acids, esters, alcohols, aldehydes, ketones, sterols and terpenes were detected in all examined samples. Using a newly available "tile-based" chromatographic alignment algorithm, we obtained a set of 341 compounds systematically occurring in male axillary odour. The principal component analysis was used to calculate Euclidean distances for all pairs of the studied male subjects. These estimates of "chemical distances" revealed to be significantly smaller for father-partner pairs of individual...

Tesis por compendio / [ES] La citricultura se enfrenta a escenarios ambientales cambiantes que provocan diferentes estreses bióticos y abióticos que pueden dificultar la producción o afectar a la calidad de la fruta. El patrón sobre el cual se injerta una variedad específica es una importante herramienta para mejorar su adaptabilidad a cada área de cultivo. En la presente Tesis se realiza el estudio del efecto del patrón sobre la calidad físico-química y nutricional de la fruta en variedades de gran interés comercial en la actualidad, mandarinas 'Clemenules' y 'Tango' y naranjas sanguinas 'Tarocco Rosso' y 'Moro'. En 'Clemenules' se llevó a cabo la evaluación de la calidad de la fruta de árboles injertados sobre ocho patrones en tres momentos de cosecha durante dos campañas. Los patrones Forner-Alcaide 13 y C-35 destacaron por adelantar el cambio de color, lo que es de gran interés comercial. Por otra parte, Forner-Alcaide V17 destacó por mantener niveles óptimos de acidez hasta el final de la campaña y presentar el mayor contenido en vitamina C, flavonoides, glucosa y fructosa. Carrizo Citrange también indujo altas concentraciones de sacarosa y vitamina C. 'Tango' es una mandarina de reciente introducción en el área mediterránea de gran interés por su periodo de recolección tardío. En esta Tesis se abordó el estudio de los cambios en la calidad fisicoquímica, nutricional y sensorial de la mandarina 'Tango' injertada sobre dos patrones (Carrizo Citrange y Forner-Alcaide 5) en las dos áreas principales de producción de Andalucía. Los resultados revelaron que la calidad de la fruta se vio influenciada por la localización de las parcelas, lo que se relacionó con la composición de la textura del suelo. En ambas localizaciones, Forner-Alcaide 5 indujo mayor contenido en acidez, sólidos solubles totales, sacarosa, vitamina C y ácido cítrico en la fruta. Las determinaciones físico-químicas, junto con la evaluación sensorial permitieron establecer el momento óptimo de recolección dependiendo de las diferentes condiciones estudiadas. También se ha incluido un estudio del comportamiento postcosecha de esta variedad, ya que no existían datos en nuestras condiciones de cultivo. La mandarina 'Tango' presentó síntomas externos de daños por frío a partir de los 20 días almacenada a 1°C y 5°C. Se realizó un estudio micro-estructural para caracterizar la alteración. Los frutos del patrón Forner-Alcaide 5 presentaron una menor incidencia de los daños por frío. El almacenamiento a 9°C no comprometió la calidad externa o interna. Dentro del grupo de naranjas, en los últimos años existe una creciente demanda por las naranjas sanguinas para su consumo en fresco. Para evaluar el efecto del patrón se tomaron las variedades 'Moro' y 'Tarocco Rosso' injertadas sobre ocho patrones. La calidad interna se vio afectada por el momento de cosecha, siendo más evidente en 'Moro'. En ambas variedades el patrón afectó a los parámetros de calidad durante la maduración. En 'Moro', se observó una reducción en el color del zumo debido a la degradación de los antocianos, siendo los patrones C-35, Macrophylla y Volkameriana los que mostraron un mayor descenso. Esta degradación se relacionó con los cambio de la temperatura durante el periodo de recolección. En 'Tarocco Rosso' no se evidenció ninguna degradación, lo que sugiere que esta variedad es menos sensible a los cambios de temperatura. En esta variedad Forner-Alcaide 5 y Forner-Alcaide 13 produjeron fruta con mayor contenido en antocianos y azúcares. Además se llevó a cabo el estudio de la aptitud a la frigoconservación de las variedades de sanguinas 'Tarocco Rosso' y 'Sanguinelli'. Mientras que la calidad interna no se vio afectada por el almacenamiento (1°C, 5°C y 9°C) durante 45 días, la fruta presentó síntomas de daños por frío a 1°C. 'Sanguinelli' presentó mayor incidencia que 'Tarocco Rosso'. Estas sanguinas se pueden almacenar entre 5 y 9°C / [CA] La citricultura s'enfronta constantment a escenaris ambientals canviants que provoquen diferents estressos biòtics i abiòtics. El patró sobre el qual s'empelta una varietat específica és una important eina per a millorar la seua adaptabilitat agronòmica en cada àrea de cultiu. En la present Tesi s'ha dut a terme l'estudi de l'efecte del patró sobre la qualitat físic-química i nutricional de la fruita en varietats de gran interés comercial, mandarines 'Clemenules' i 'Tango' i, taronges sanguines 'Tarocco Rosso' i 'Moro'. En 'Clemenules' es va dur a terme l'avaluació de la qualitat de la fruita d'arbres empeltats sobre huit patrons en tres moments de collita, en dues campanyes. Entre els patrons avaluats, Forner-Alcaide 13 i C-35 van destacar per avançar el canvi de color. D'altra banda Forner-Alcaide V17 va destacar per mantindre nivells òptims d'acidesa fins al final de la campanya i va presentar el major contingut en vitamina C, flavonoides, glucosa i fructosa. Carrizo Citrange també va induir altes concentracions de sacarosa i vitamina C en la fruita. 'Tango' és una mandarina de recent introducció en l'àrea mediterrània amb gran interés pel seu període de recol·lecció que comença quan finalitza el de les clementines. En la present Tesi es van estudiar els canvis en la qualitat físic-química, nutricional i sensorial de la mandarina Tango empeltada sobre dos patrons (Carrizo Citrange i Forner-Alcaide 5) durant el període de collita en les dues àrees principals de producció d'Andalusia. La qualitat de la fruita es va veure influenciada per la localització, la qual cosa es va relacionar amb la composició de la textura del sòl. En totes dues localitzacions, Forner-Alcaide 5 va ser el patró que va induir major contingut en acidesa, sòlids solubles totals, sacarosa, vitamina C i àcid cítric en la fruita. Les determinacions físic-químiques i l'avaluació sensorial van permetre establir el moment òptim de recol·lecció depenent de les diferents condicions estudiades. També s'ha inclòs un estudi del comportament postcollita d'aquesta varietat, ja que no existien dades en les nostres condicions de cultiu. La mandarina 'Tango' va presentar símptomes externs de danys per fred a partir dels 20 dies emmagatzemada a 1°C i 5°C. Es va realitzar un estudi micro-estructural per a caracteritzar l'alteració provocada per les baixes temperatures. Els fruits del patró Forner-Alcaide 5 van presentar una menor incidència dels danys per fred. L'emmagatzematge a 9°C no va comprometre la qualitat externa o interna d'aquesta varietat. Dins del grup de taronges, en els últims anys existeix una creixent demanda per les taronges sanguines pel seu consum en fresc. Per a avaluar l'efecte del patró sobre sanguines es van prendre dues varietats, 'Moro' i 'Tarocco Rosso' empeltades sobre huit patrons. La qualitat interna es va veure influenciada pel moment de collita, la qual cosa va ser més evident en la varietat 'Moro'. En totes dues varietats el patró va afectar els canvis en els paràmetres de qualitat estudiats. En 'Moro', es va observar una reducció en el color del suc degut a la degradació del antocians. Aquesta degradació es va relacionar amb el canvi de la temperatura experimentada durant el període de recol·lecció. 'Tarocco Rosso' és menys sensible als canvis de temperatura. En aquesta varietat els patrons Forner-Alcaide 5 i Forner-Alcaide 13 van produir la fruita amb major contingut en antocianos i sucres. A mes s'aporta l'estudi de l'aptitud a la frigoconservació en les sanguines 'Tarocco Rosso' i 'Sanguinelli'. Mentre que la qualitat interna no es va veure afectada per l'emmagatzematge a cap de les temperatures assajades (1°C, 5°C i 9°C) durant 45 dies, la fruita va presentar símptomes de danys per fred a 1°C. `Sanguinelli' va presentar major incidència que 'Tarocco Rosso'. La fruita es pot emmagatzemar entre 5°C i 9°C durant 30 dies en el cas de 'Sanguinelli' i fins a 45 en e / [EN] Citriculture faces changing environmental scenarios that cause biotic and abiotic stress. The rootstock onto which a specific variety is grafted is an important tool to help to improve its agronomic adaptability to each crop area. The present Thesis was carried out to study the effect of rootstock on physico-chemical and nutritional fruit quality in some varieties of commercial interest today: 'Clemenules' and 'Tango' mandarins, and 'Tarocco Rosso' and 'Moro' blood oranges. In 'Clemenules', the fruit of the trees grafted into eight rootstocks at three harvest times was evaluated by performing studies during two seasons. Forner-Alcaide 13 and C-35 Citrange stood out for their earlier color change, which is very interesting for this variety, in which early harvesting is a relevant aspect from the commercial point of view. Forner-Alcaide V17 stood out for maintaining optimum acidity levels until the season ended and presented the highest contents in vitamin C, flavonoids, glucose and fructose. Carrizo Citrange brought about high concentrations of sucrose and vitamin C in fruit. 'Tango' is a mandarin variety that has been recently introduced into the Mediterranean Region. Its harvest time is very interesting because it starts when that of clementines ends. The present Thesis studies changes in the physico-chemical, nutritional and sensorial quality of 'Tango' fruit grafted onto two rootstocks (Carrizo Citrange and Forner-Alcaide 5) during the harvest period in the two main production areas in Andalusia. The results revealed that fruit quality during harvest was influenced by the location, which was particularly related to soil texture composition. In both areas, Forner-Alcaide 5 was the rootstock that induced higher acidity content, and more total soluble solids, sucrose, vitamin C and citric acid in fruit. The physico-chemical determinations, along with the sensorial evaluation, allowed the optimum harvest time to be established depending on the different studied conditions. This Thesis also includes a study about this variety's postharvest behavior as no data are available for our crop conditions. The 'Tango' mandarin presented outer chilling injury symptoms after being stored for 20 days at 1°C and 5°C. A microstructural study was done to characterize the alteration caused by low temperatures. The Forner-Alcaide 5 rootstock fruit showed a lower chilling injury incidence. Storage at 9°C did not compromise quality fruit. Among oranges, demand for blood oranges to be eaten fresh has grown in recent years, basically due to their high content in anthocyanins and their positive effect for human health. To assess the effect that rootstock had on blood oranges, two varieties were taken, 'Moro' and 'Tarocco Rosso', grafted onto eight rootstocks. Internal quality was strongly influenced by harvest time, which was more evident for 'Moro'. In both varieties, rootstock affected changes in the quality parameter studied. In 'Moro', juice color faded as anthocyanins degraded, and rootstocks C-35 Citrange, Macrophylla and Volkameriana showed the most marked reduction. Such anthocyanin degradation was related to the change in temperature that took place during the harvest period. In 'Tarocco Rosso', anthocyanins did not undergo degradation, which suggests that this variety is less sensitive to changes in temperature. In this variety, rootstocks Forner-Alcaide 5 and Forner-Alcaide 13 gave fruit with a higher content of anthocyanins and sugars. This Thesis also includes a study of the suitability of cold storage of two blood orange varieties: 'Tarocco Rosso' and 'Sanguinelli'. Although storage at any tested temperature (1°C, 5°C and 9°C) did not affect internal quality for 45 days, fruit displayed chilling injury symptoms at 1°C, with a higher incidence for 'Sanguinelli' than for 'Tarocco Rosso'. Fruit can be stored between 5°C and 9°C for 30 days for 'Sanguinelli' and for up to 45 days with 'Tarocco Rosso'. / This study has been supported by Instituto Valenciano de Investigaciones Agrarias and co-financed by FEDER and European Social Fund. The authors thank Anecoop S. Coop. and Frutaria Agricultura, S.L for supplying the fruit herein used and its technical support. / Morales Alfaro, J. (2021). Effect of Rootstock on the Fruit Quality of Mandarins "Clemenules" and "Tango", and Blood Oranges "Tarocco Rosso" and "Moro" [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/165858 / Compendio

De nombreuses applications industrielles spécifiques dans les secteurs tels que l'automobile, le médical et le spatial, requièrent un très haut niveau de fiabilité. Ce type d'applications fonctionnant sous des contraintes sévères (haute température, corrosion, vibration, radiations,…) impose aux industriels des spécifications particulières en termes de fiabilité et de consommation d'énergie. Dans ce contexte, les travaux menés ont pour objectif d'étudier la fiabilité des mémoires Flash embarquées pour des applications faible consommation et à forte contrainte de fiabilité. Après une introduction orientée sur les deux volets d'étude que sont la caractérisation électrique et le test de mémoires non volatiles, un modèle physique capable de modéliser le courant de SILC a été développé. Cet outil permet de répondre à la problématique de perturbations en lecture (read disturb) et donne aux designers et technologues un moyen d'estimer le taux de défaillance de cellules mémoires en fonction de paramètres physiques, géométriques et électriques ainsi que des moyens d'action afin de minimiser ce phénomène indésirable. La fiabilité (oxyde tunnel, endurance) et les performances (consommation énergétique) de la cellule Flash sont ensuite étudiées en explorant les variations de paramètres du procédé de fabrication et des conditions électriques de fonctionnement. Enfin, une étude originale menée en temps réel sur plus de 15 mois est consacrée à la fiabilité en rétention des mémoires Flash soumises aux effets des particules radiatives présentes dans l'environnement naturel terrestre. / Many specific applications used in automotive, medical and spatial activity domains, require a very high level of reliability. These kinds of applications, working under severe constraints (high temperature, corrosion, vibration, radiations…) challenge memory manufacturers and impose them particular specifications in terms of reliability and energy consumption. In this context, work presented in this thesis aim at studying embedded Flash memories reliability for low power and high reliability applications. After an introduction oriented on areas of electrical characterizations and Test of non-volatile memories, a physical model of SILC leakage current is developed. This tool is used to answer to disturbs problematic and gives to designers and technologists a way to estimate the failure rate of memory cells according to physical, geometrical and electrical parameters, giving leads to minimize this unwanted phenomenon. Reliability (tunnel oxide, cell endurance) and performances (energy consumption) of Flash memory cell are then studied exploring process parameters variations and electrical conditions optimizations. Finally, an original real-time experiment over more than 15 months is focused on Flash memories retention reliability due to irradiative particles effects of natural terrestrial environment.