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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Etude de l’expression de l'homéoprotéine Engrailed dans l’hippocampe et de ses effets sur la complexité dendritique / Engrailed : hippocampal expression and role in dendritic complexity

Soltani, Asma 25 February 2014 (has links)
Engrailed (En) est un facteur de transcription important pour la mise en place de la segmentation de l’embryon et du plan d’organisation antéro-postérieur. Comme d’autres membres de la famille des homéoprotéines, Engrailed peut aussi agir comme une molécule de signalisation extracellulaire, internalisable grâce à son domaine « pénétratine » et stimulant dans la cellule cible la transcription ou la traduction des ARNm. De cette façon, Engrailed guide les axones en modifiant la traduction dans le cône de croissance axonal et l’infusion cérébrale d’Engrailed protège les neurones dopaminergiques dans un modèle de la maladie de Parkinson en augmentant la traduction de protéines mitochondriales. Des troubles cognitifs et un déficit des interactions sociales ont été observés chez les souris En1+/- et les souris En2-/-. Une augmentation de l’expression d’En2 a aussi été observée chez des patients atteints de troubles du spectre autistique. Néanmoins, le lien entre les modifications de l’expression d’Engrailed et l’autisme ne sont pas compris. L’objectif de cette thèse a été d’étendre notre connaissance des fonctions d’Engrailed dans une région télencéphalique où elle est a priori peu exprimée (l’hippocampe). Nos résultats confirment l’expression d’En1 et En2 dans l’hippocampe mature et décrivent les variations de l’expression de ces gènes au cours du développement de cette structure. En1 et En2 présentent des patrons d’expression différents pendant la première semaine postnatale et chez l’adulte suggérant que des variations du dosage génique d’Engrailed sont liées à certaines phases du développement, en particulier au début de la synaptogenèse. Nous avons également découvert que dans les cultures de cellules d’hippocampe Engrailed est exprimé dans les neurones et que son expression est plus forte dans les neurones GABA-ergiques, notamment dans leurs prolongements dendritiques et axonaux. Nous avons constaté qu’un excès d’Engrailed (décrit dans certains cas de TSA) augmente la complexité dendritique ainsi que la densité des épines dendritiques plastiques mais sans augmenter parallèlement la formation de synapses matures excitatrices. Nous avons observé des variations de densité des épines dendritiques chez les souris En2-/- et les souris En1+/-, ce qui confirme l’implication d’Engrailed dans leur formation ou leur stabilisation. Si dans nos conditions expérimentales l’excès d’Engrailed ne modifie pas la densité des synapses, un mutant d’Engrailed qui présente une interaction réduite avec eIF4E est moins efficace qu’Engrailed pour augmenter la densité des épines et diminue la densité des boutons présynaptiques et le synaptic matching. Ces résultats indiquent que l’interaction avec eIF4E régule au moins en partie les effets d’Engrailed sur la spinogenèse et suggèrent également une implication d’Engrailed dans la formation ou la stabilisation des boutons présynaptiques. Le rôle clef d’eIF4E dans la traduction permet de postuler que certains effets d’Engrailed observés dans notre étude pourraient dépendre de la synthèse protéique. Nos résultats montrent à cet égard qu’Engrailed augmente la synthèse protéique dans les neurones d’hippocampe. Cette traduction est différente de celle induite par la LTP chimique (LTPc) car insensible à l’action des oligomères synthétiques d’AβO, responsables sous leur forme naturelle de synaptopathies dans le contexte de la maladie d’Alzheimer. Engrailed permet également de restaurer la traduction défaillante de neurones issus de souris TG2576, modèles de la maladie d’Alzheimer. Dans leur ensemble, nos résultats identifient Engrailed comme un nouvel acteur de la plasticité dendritique. Ils révèlent qu’un excès d’Engrailed au cours de la synaptogenèse modifie les caractéristiques des dendrites, une situation susceptible d’altérer les caractéristiques fonctionnelles du réseau dendritique dans une situation de surexpression pathologique de la protéine. (...) / Engrailed (En) is an important transcription factor in embryo’s segmentation and anterior-posterior axis establishment during early embryogenesis. As several homeoproteins, Engrailed can act as an extracellular signalling molecule which can be internalized by target cells thanks to its penetratin domain and act through transcriptional and/or translation dependent mechanisms. Engrailed has for instance, translation-dependent effects on axonal guidance and cerebral infusion of Engrailed protects dopaminergic neurons in a Parkinson disease model by increasing mitochondrial protein translation. Also, cognitive defects were observed in En1+/+ and En2-/- and En2 expression is increased in ASD patients. This work consisted in extending the knowledge of Engrailed expression and functions. We explored the links with a telencephalic structure where it is a priori fewly expressed (hippocampus). Our results confirm En1 and En2 expression in the mature hippocampus and describe their respective expression along the development of this structure. En1 and En2 have different expression patterns during the first post-natal week as well as in the adulthood suggesting a genetic dosage of Engrailed during the development, specifically with the beginning of synaptogenesis. We also reveal that Engrailed, expressed in hippocampal neurons, is more expressed in GABA-ergic neurons, notably in their dendritic and axonal neurites. We observe that an excess of Engrailed (described in some ASD cases) increases dendritic complexity as well as plastic dendritic spine density, without affecting mature excitatory synapses. We show that En2-/- and heterozygote En1 mice have variations in dendritic spine density, which confirms that Engrailed is involved either in their formation or stabilization. Even though our experiments show no modification of synapse density with an excess of Engrailed, a mutant showing a decreased eIF4E interaction and less efficient than wild type Engrailed to increase dendritic spine density, decreases presynaptic button density and synaptic matching. Those results indicate that eIF4E interaction with Engrailed is, at least in part, responsible for its effects on spinogenesis and suggest a role of Engrailed in presynaptic button formation/stabilization. Key-role of eIF4E in translation allow to hypothesize that some of Engrailed effects we report could be translation dependent. In this sense, our results show that Engrailed is able to increase proteic synthesis in hippocampal neurons. This translation is different from the one induced by chemical LTP (LTPc): it is not altered by synthetic AβO, which are the main toxic agent when produced at abnormally high levels in Alzheimer disease. Engrailed is also able to restore defaulting translation in neurons from Alzheimer disease mice model (TG2576). As a whole, our results identify Engrailed as a novel actor in dendritic plasticity. They reveal that an excess of Engrailed during synaptogenesis can modify dendrite characteristics. This can lead to dendritic network dysfunction in a context of pathologic surexpression of Engrailed. Our observations open to new perspectives contributing to a better understanding of the relationship between Engrailed and ASD. Finally, this work lays the foundation to potentially fruitful links between Engrailed and AβOligomers signalling pathways, where modulation of protein synthesis could be a therapeutic lever in physiopathologic conditions.
22

ÉTUDE D'UN PROCÉDÉ D'ADSORPTION TSA (Temperature Swing Adsorption)<br />À CHAUFFAGE ET REFROIDISSEMENT INDIRECTS

Clausse, Marc 09 December 2003 (has links) (PDF)
Ce travail concerne l'utilisation d'un nouveau procédé TSA (Temperature Swing Adsorption) pour le traitement d'effluents gazeux. Ce nouveau procédé fait appel à un adsorbeur équipé d'un échangeur interne. La phase de chauffage (désorption), est assurée par condensation de vapeur d'eau tandis que lors du refroidissement (adsorption), de l'eau du réseau circule dans l'échangeur. Une étude expérimentale en mono et multiconstituants (CO2 et/ou C2H6) a permis de mettre en évidence l'intérêt d'un chauffage rapide de l'adsorbeur pour obtenir un enrichissement important des produits désorbés. Le comportement local de ce nouvel adsorbeur a été comparé à celui d'un adsorbeur TSA conventionnel au moyen d'un modèle numérique préalablement validé à partir d'expériences. En phase d'adsorption, la température d'alimentation et de la température initiale du lit n'ont que peu d'influence sur les performances du nouvel adsorbeur. En phase de désorption, une température de chauffage élevée aboutit à une diminution de la durée de l'étape, contrairement au cas d'un adsorbeur conventionnel. Grâce à une étude paramétrique effectuée pour des cycles, une plage de conditions opératoires (température de désorption, débits de purge) a été déterminée pour une application spécifique. Enfin, une pré-étude sur la capture de toluène a été réalisée en vue d'évaluer l'utilité de ce procédé pour la capture de composés organiques volatils (COV). Le fort enrichissement (160) obtenu en désorption permet d'augmenter la température de rosée et ainsi de faciliter sa récupération.
23

Automatic diagnostic system for I-shift transmission using vibration analysis / Automatiserat feldetekteringssystem för I-shift växellådor med hjälp av vibrationsanalys

Lennartsson, Richard January 2010 (has links)
<p>This master’s thesis work was performed at Volvo Powertrain in Köping, Sweden, which manufactures gearboxes and integrated transmission systems for heavy vehicles. The thesis is a continuation of a previous master’s thesis performed at the Köping factory in 2009. After manufacturing and assembly, each gearbox is manually validated to ensure the gearbox quality and functionality. When validating the gearbox gears, the operator shifts the gearbox in a predefined manner and listens for irregularities. If an error sound is heard the operator must then locate the source of error. With numerous of cog wheels rotating at the same time this task requires extensive knowledge and experience of the operator. The main objective is to develop an automatic diagnostic system for detection of cog errors and assist the operator in the process of locating the faulty component.</p><p>The work consists of two parts. In the first part the automatic diagnostic system is developed and a database of gearbox recordings is stored. The amounts of logged non-faulty gearboxes are significantly much larger (50) than the logged faulty gearboxes (1). Therefore, when determining thresholds needed for the diagnosis, the data obtained from the non-faulty gearboxes are used. Two statistical methods are presented to extract the thresholds. The first method uses an extremevalue distribution and the other method a Gaussian distribution. When validated, both methods did successfully detect on cog faults. In the second part an investigation is made of how shaft imbalance can be detected and implemented in the developed system.</p><p>Volvo Powertrain continually follows-up all faults found at the validation station to ensure the quality of their work and eliminate the sources of error. During system testing one logged gearbox was found faulty. The automatic diagnostic system did successfully detect and locate the faulty component which later also was confirmed when the gearbox was dismounted. With only one detected error it is difficult to conclude the system performance and further testing is required. However, during the testing no false detections were made.</p>
24

Automatic diagnostic system for I-shift transmission using vibration analysis / Automatiserat feldetekteringssystem för I-shift växellådor med hjälp av vibrationsanalys

Lennartsson, Richard January 2010 (has links)
This master’s thesis work was performed at Volvo Powertrain in Köping, Sweden, which manufactures gearboxes and integrated transmission systems for heavy vehicles. The thesis is a continuation of a previous master’s thesis performed at the Köping factory in 2009. After manufacturing and assembly, each gearbox is manually validated to ensure the gearbox quality and functionality. When validating the gearbox gears, the operator shifts the gearbox in a predefined manner and listens for irregularities. If an error sound is heard the operator must then locate the source of error. With numerous of cog wheels rotating at the same time this task requires extensive knowledge and experience of the operator. The main objective is to develop an automatic diagnostic system for detection of cog errors and assist the operator in the process of locating the faulty component. The work consists of two parts. In the first part the automatic diagnostic system is developed and a database of gearbox recordings is stored. The amounts of logged non-faulty gearboxes are significantly much larger (50) than the logged faulty gearboxes (1). Therefore, when determining thresholds needed for the diagnosis, the data obtained from the non-faulty gearboxes are used. Two statistical methods are presented to extract the thresholds. The first method uses an extremevalue distribution and the other method a Gaussian distribution. When validated, both methods did successfully detect on cog faults. In the second part an investigation is made of how shaft imbalance can be detected and implemented in the developed system. Volvo Powertrain continually follows-up all faults found at the validation station to ensure the quality of their work and eliminate the sources of error. During system testing one logged gearbox was found faulty. The automatic diagnostic system did successfully detect and locate the faulty component which later also was confirmed when the gearbox was dismounted. With only one detected error it is difficult to conclude the system performance and further testing is required. However, during the testing no false detections were made.
25

Co-cured composite joint strength investigation based on behavior characterization of [0/±θ/90]s family

Tan, Xinyuan 17 November 2008 (has links)
Joints provide a path for transfer of load and are important components in an assembly of structures, particularly in translating joint strength improvements directly to significant cost savings. This cost savings is more evident in composite joints since manufacturing of more complex single piece components results in a reduction of both part count and labor. An improvement in joint strength for co-cured composite joints through minimized free-edge delamination was investigated for quasi-isotropic [0/±45/90]s lay-up based on the quantitative assessments of the quasi-static and fatigue strength and qualitative understanding of the fatigue damage initiation and propagation for the [0/±θ/90]s family of co-cured composite joints. A previously proposed co-cured joint concept, the Single Nested Overlap (SNO) joint, was compared against a Straight Laminate (SL) and a single lap joint. The SL represents a "perfect" joint and serves as an upper bound whereas the single lap joint represents the simplest generic joint and is the base design for the SNO joint concept. Three categorized failure types, which represented predominant failure modes in the SL, single lap and SNO joints, along with two different fatigue strength indicators were used for quasi-static and fatigue strength comparison. With fatigue run-out defined at 1 x 106 cycles, the fatigue damage initiation and propagation at high loadings was monitored with an Infrared Thermoelastic Stress Analysis (IR-TSA) technique, while a damage type comparison was used at low loadings. Quasi-static Acoustic Emission (AE) counts were observed to be Fatigue Limit (FL) predictors for [0/±θ/90]s SL and SNO joints. The validity of these FL predictors were also assessed in the damage type comparison.
26

Adaptation de méthodes d’évaluation dans le cadre de la conception d’une application numérique pour un jeune public avec troubles du spectre autistique : étude au cours de la conception et de l'évaluation de l’application çATED au sein d'une ULIS TED / Adaptation of evaluation methods in the design of a digital application for a young audience with autism spectrum disorders : Study during the conception and during the evaluation of the application çATED within an ULIS TED

Guffroy, Marine 07 April 2017 (has links)
La prise en considération des spécificités du public cible et des contextes d’usage d’une application interactive peut interroger les principes méthodologiques généralement recommandés pour la conception et l’évaluation d’application informatique. Dans le cas de la création d’un outil dédié à un jeune public avec TSA (Troubles du Spectre Autistique), les difficultés de communication et les altérations des interactions sociales de ces derniers empêchent la mise en œuvre d’une méthodologie « ordinaire » de conception centrée utilisateur. Au-delà de la prise en considération du potentiel, établi, qu’offre le numérique pour le jeune public avec TSA, il s’agit d’identifier et de mettre en œuvre les méthodes et techniques utiles à l’évaluation des prototypes proposés, en tenant compte des caractéristiques du public et de son contexte quotidien en structure scolaire.Les travaux de recherche présentés dans cette thèse se situent dans le domaine des interactions hommes-machines (IHM). Ils questionnent les principes méthodologiques de conception centrée utilisateur : Comment répondre aux objectifs d’évaluation quand la communication verbale n’est pas garantie ? Quel rôle pour l’utilisateur cible dans le cycle de conception-évaluation ? Quels rôles pour l’entourage humain et spécialisé ? Comment observer et analyser l’usage d’un logiciel sur tablette dans le contexte quotidien du public cible ?Plus précisément, la problématique porte sur l’adaptation des méthodes d’évaluation ordinaires aux caractéristiques et comportements spécifiques d’un public extraordinaire. / Taking into account the specificities of the target audience and the contexts of use of an interactive application imply to question the generally recommended methodological principles for computer application design and evaluation. In the case of the creation of a tool dedicated to a young audience with Autistic Spectrum Disorders (ASD), communication difficulties and alterations in their social interactions prevent the implementation of an "ordinary", user-centered design methodology. Beyond the consideration of the established potential offered by digital technology for young people with ASD, it is a question of identifying and implementing the methods and techniques useful in order to evaluate the proposed prototypes, taking into account the characteristics of the public and its everyday context in school structure.The research presented in this thesis belong to the field of human-machine interactions (HMI). It questions the methodological principles of user-centered design: How to meet evaluation objectives when verbal communication is not guaranteed? What role for the target user in the design-evaluation cycle? What are the roles for the human and specialized relatives? How to observe and analyze the use of tablet software in the daily context of the target audience?More specifically, the research concerns the adaptation of ordinary methods of evaluation to the specific characteristics and behaviors of an extraordinary audience.
27

O combate à pobreza em uma economia pós-comunista: os programas de transferência de renda do Azerbaijão como vetores de desenvolvimento

Santana, Vinícius Silva 12 December 2017 (has links)
Submitted by Vinícius Santana (vinigoleirao@gmail.com) on 2018-04-10T00:02:18Z No. of bitstreams: 1 Dissertação de Mestrado - Vinicius Silva Santana.pdf: 4311247 bytes, checksum: da4f0c629a4223092cdb12dc66a3ca13 (MD5) / Approved for entry into archive by Setor de Periódicos (per_macedocosta@ufba.br) on 2018-04-10T17:46:18Z (GMT) No. of bitstreams: 1 Dissertação de Mestrado - Vinicius Silva Santana.pdf: 4311247 bytes, checksum: da4f0c629a4223092cdb12dc66a3ca13 (MD5) / Made available in DSpace on 2018-04-10T17:46:18Z (GMT). No. of bitstreams: 1 Dissertação de Mestrado - Vinicius Silva Santana.pdf: 4311247 bytes, checksum: da4f0c629a4223092cdb12dc66a3ca13 (MD5) / CAPES; CNPq; Alexander von Humboldt Foundation / Os programas de transferência de renda foram adotados por diversas nações ao redor do globo como parte de sua estratégia de desenvolvimento, entendida por alguns como uma revolução do Sul-Global, enquanto outros a consideraram como uma resposta das nações em desenvolvimento à apelação das instituições de Bretton Woods de focalização nas políticas de combate à pobreza. O Azerbaijão implementou o Programa de Assistência Social Dirigida, ou TSA (Targeted Social Assistance), na tentativa de reduzir os crescentes números relacionados à pobreza e à desigualdade no país. Porém, além de combater a pobreza, era preciso fomentar o pleno desenvolvimento da estrutura de uma economia de mercado e transformar a relação entre homem e sociedade desenvolvida na União Soviética; assegurar a existência de um plano de proteção social e de desenvolvimento de capital humano; e, ainda, lidar com questões relacionadas a conflitos, refugiados, pessoas deslocadas internamente e o tamanho crescente do “mercado informal”. Assim, esta dissertação de mestrado visa compreender de que maneira o TSA se articula com outras políticas para, não apenas combater a pobreza, mas também, em nível mais amplo, promover o desenvolvimento do Azerbaijão. Desta forma, faz-se, por meio de uma abordagem histórico-teórica, um resgate dos Estudos Soviéticos e da negação do homem econômico e do modelo de desenvolvimento soviético em contraste com o desenvolvimento capitalista, suas políticas e conceitos que “invadiram” o Azerbaijão durante os primeiros anos da transição, principalmente o conceito de pobreza, desigualdade social e do próprio capitalismo. Ainda, explora-se os diversos programas de proteção social pré e pós-transição e as relações entre o TSA e o mercado informal para se argumentar que o TSA é um instrumento fundamental no desenvolvimento do Azerbaijão. / Cash transfer programs were adopted by several countries across the globe as part of their development strategy. Some people argue that such a strategy is part of a revolution from the Global South, while others see it as an answer given by the developing countries to claims of the Bretton Woods organizations for focalization in poverty alleviation policies. Azerbaijan implemented its Targeted Social Assistance (TSA) program as a way to reduce the growing numbers in the poverty and inequality indexes. More than only fighting poverty, however, Azerbaijan had to foster the development of a fully-functioning market-economy structure and to transform the relation created in the Soviet Union between men and society; to guarantee the existence of a social protection and human capital development plan; and, yet, deal with questions related to conflicts, refugees, internally displaced persons and the growth of the shadow economy. Therefore, this master’s thesis aims to comprehend how TSA articulates with other policies to, not only fight poverty, but also, in a broader sense, promote Azerbaijan’s development. Hence, through a historical and theoretical approach, it brings to light issues of the Soviet Studies and the negation of the economic man as well as the Soviet model of economic development in contrast with the capitalist one, its politics and concepts that “invaded” Azerbaijan in the first years of transition. Special note is given to the concepts of poverty, inequality and capitalism itself. The social security and social protection programs both prior and post-transition and the relations between TSA and the informal sector are also examined in order to argue that TSA is a key instrument used for the development of Azerbaijan. / Bəzi insanların fikrinə görə, pul köçürmə proqramları Qlobal Cənubdan bir inqilabi hissəsidir. Digərlərinin fikrinə görə, bu proqramlar inkişaf etməkdə olan ölkələrin Dünya Bankının fokalizasiya siyasətinə bir cavabıdır. Hansı halda, bu proqramlar onların inkişaf strategiyası və yoxsulluqla mübarizə aparmaq üçün çox ölkələrlə qəbul edildi. Yoxsulluğun və bərabərsizliyin artan rəqəmlərini azaltmaq üçün, Azərbaycan Ünvanlı Dövlət Sosial Yardımı (ÜDSY) proqramını yerinə yetirdi. Amma, Azərbaycan də bazar iqtisadiyyatın strukturunu dəyişməlidir və insanlar və cəmiyyət arasında Sovet İttifaqından qalma sosial əlaqələri transformasiya etməlidir; sosial müdafiə sisteminin və insan kapitalının inkişaf planına zamin durmalıdır; və, bununla yanaşı, münaqişə, qaçqınlar, məcburi köçkünlər və artan kölgə iqtisadiyyatı problemləri ilə məşğul olmalıdı. Odur ki, bu magistr dissertasiyası yalnız yoxsulluqla mübarizə proqramını deyil, ÜDSY-nın Azərbaycanın inkişafını təşviq etmək məqsədi ilə başqa məsələlərlə necə məşğul olduğunu alamağa çalışır. Beləliklə, tarixi və nəzəri yanaşmalar metodu ilə, bu iş Sovet Tədqiqatlarınnın problemlərini, müzakirə edərək homo economicus-un inkarı və kapitalizm və sosializm siyasəti və anlayışları haqqında təklif edir. Həmçinin, bu iş keçid dövrü iqtisadiyatı, yoxsulluq qeyri-bərabərsizlik və kapitalizmə diqqət yetirir. Keçiddən əvvəl və sonrakı sosial təhlükəsizlik və sosial müdafiə proqramları da araşdırılır eləcə də ÜDSY-nın və kölgə iqtisadiyyatın arasında, göstərmək üçün ki, Azərbaycanın inkişafında ÜDSY-nın aparıcı rolu var.
28

Valorização de caroços de frutas regionais e captura de CO2

Fiuza-Junior, Raildo Fiuza 20 June 2016 (has links)
Submitted by Raildo Junior (raildofiuza@gmail.com) on 2018-06-09T15:23:45Z No. of bitstreams: 1 Tese_Raildo Alves Fiuza-Junior.pdf: 3817573 bytes, checksum: 4110410e6eb185be2b68b9e9b00b254c (MD5) / Approved for entry into archive by NUBIA OLIVEIRA (nubia.marilia@ufba.br) on 2018-06-18T17:58:36Z (GMT) No. of bitstreams: 1 Tese_Raildo Alves Fiuza-Junior.pdf: 3817573 bytes, checksum: 4110410e6eb185be2b68b9e9b00b254c (MD5) / Made available in DSpace on 2018-06-18T17:58:36Z (GMT). No. of bitstreams: 1 Tese_Raildo Alves Fiuza-Junior.pdf: 3817573 bytes, checksum: 4110410e6eb185be2b68b9e9b00b254c (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPQ) / Caroços de frutas regionais (tamarindo, umbu, seriguela e cajá), provenientes de uma indústria de polpa de frutas foram caracterizados utilizando as normas ASTM, quantificação dos componentes por Van Soest, FTIR, DRX, TG, DSC e EDX. As biomassas estudadas apresentaram um grande potencial para o uso na geração de energia e produção de carvão. Os caroços de cajá foram utilizados inteiros como matéria prima para a produção de carvões ativados a 500°C e posteriormente avaliados como adsorvente na captura de CO2 . Os materiais foram ativados quimicamente por impregnação com HNO3, H3PO4 e KOH ou fisicamente ativado com CO2 após uma prévia pirólise. As amostras de carvão ativado foram caracterizadas por EDX, MEV, TGA, espectroscopia Raman, análise textural (BET, Langmuir, DFT e Dubinin-Astakhov) e por titulação ácido-base. A capacidade de adsorção CO2 e regeneração do adsorvente foi investigada por TGA. Os resultados indicam que a capacidade de adsorção de CO2 pode ser maximizada em superfícies altamente básica de microporos menores que 1 nm. O carvão ativado com KOH mostrou capacidade elevada e estável adsorção de CO2 durante 10 ciclos a 40°C. Num segundo momento a biomassa triturada e pirolisada a 400°C foi impregnada com KOH e ativada em 500 e 700°C. Esses novos materiais foram caracterizados pelos métodos já citados, acrescentando a caracterização por DRX para avaliar os parâmetros cristalográficos da estrutura carbonácea. Em geral, diminuiu a grafitização dos carvões ativados e uma melhora significativa da estrutura microporosa foi observada com o aumento a temperatura de 500 para 700°C. Poros na faixa de tamanho de 0,85-1,0 nm foram comprovados como uma característica importante para a adsorção de CO2 em baixas pressões. Assim, a amostra ativada numa menor temperatura (500°C), apresentou elevada capacidade de adsorção por modulação de pressão nas temperaturas avaliadas (10,5 mmol g -1 CO2, a 0 °C; 7,3 mmol g-1 de CO2, a 25 °C, e 4,9 mmol g-1 de CO2, a 75 °C) e uma captura de CO2 altamente estável após 10 ciclos de adsorção-dessorção, a 75 °C. / Stones of regional fruits (tamarind, umbu, red and yellow mombin) provided by a fruit pulp industry were characterized using ASTM standards, quantification of components by the Van Soest method, FTIR, XRD, TG, DSC and EDX. These biomasses showed a great potential as raw materials for power generation and production of activated carbons. The yellow mombin stones were used as raw material for producing activated carbons at 500 °C and subsequently evaluated as adsorbent for CO2 capture. The materials were chemically activated by impregnation with HNO3, H3PO4 and KOH or physically activated with CO2 after pyrolysis.The activated carbons were characterized by EDX, SEM, TGA, Raman spectroscopy, surface area measurement (BET, Langmuir, DFT and Dubinin-Astakhov) and acid-base titration. The adsorption capacity of CO2 and regeneration of the adsorbent was investigated by TG. The results show that CO2 adsorption capacity can be maximized in highly basic surfaces with micropores smaller than 1 nm. The carbons activated with KOH showed high and stable CO2 adsorption capacity for 10 cycles at 40°C. In order to investigate the influence of the activation temperature, the biomass w as initially pyrolyzed at 400°C; impregnated with KOH and then heated at 500 and 700°C. These new materials have been characterized by the above mentioned methods and by XRD to evaluate the crystallographic parameters of the carbonaceous structure. In general, the extent of graphitization of the activated carbons decreased and a significant improvement in the microporous structure was observed with increasing the activation temperature from 500 to 700 ° C. Pores in the size range 0.85-1.0 nm have proven to be an important feature for the adsorption of CO2 at low pressures. Thus, the sample activated at a lower temperature (500°C), showed a high adsorption capacity in a PSA process at the investigated temperatures (10.5 mmol g-1 CO2 at 0°C, 7.3 g mmol-1 CO2 at 25 °C, and 4.9 mmol g-1 CO2, 75 °C) and a highly stable CO2 capture after 10 cycles of adsorption-desorption at 75 °C.
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Papel das histonas deacetilases na amígdala basolateral na modulação da memória emocional

Valiati, Fernanda Endler January 2015 (has links)
Introdução: A formação da memória envolve mudanças na expressão de genes neuronais. Remodelações epigenéticas da cromatina e modificações pós-traducionais reversíveis no DNA ou nas proteínas histonas representam mecanismos centrais na regulação da expressão gênica durante o desenvolvimento do cérebro e a aprendizagem inicial ou recuperação da memória. Desequilíbrios nos níveis de acetilação de histonas estão associados à uma ampla variedade de desordens cerebrais. Histonas deacetilases (HDACs) desempenham um papel fundamental na homeostase da acetilação de histonas e na regulação de atividades celulares fundamentais como a transcrição, tornando-as um foco de estudo. Evidências mostram que a administração de inibidores de histonas deacetilases (HDACis) restauram a memória associada à regulação da expressão gênica e melhora a memória em ratos. Estudos em modelos animais têm mostrado que a formação da memória envolve uma série de alterações bioquímicas em várias áreas do sistema nervoso central, entre as quais se destacam o hipocampo e a amígdala basolateral (BLA). Neste contexto, fármacos experimentais, como a tricostatina A (TSA), que atuam sobre mecanismos epigenéticos, têm sido recentemente propostos como potenciais terapias para o tratamento de disfunção cognitiva e memória associados a doenças neurológicas e psiquiátricas. Objetivo: Neste trabalho objetivamos compreender e elucidar o papel da acetilação de histonas em processos envolvidos na modulação da memória utilizando o fármaco TSA e se baseia na hipótese de que a atividade de HDACs é essencial para a modulação das respostas de aprendizado na tarefa de esquiva inibitória (IA). Métodos: Ratos Wistar foram canulados bilateralmente na amígdala. Os efeitos das micro-infusões intra-amigdalares de TSA foram observados na consolidação e na extinção da memória após o treino na tarefa de esquiva inibitória e nos níveis do fator neurotrófico derivado do cérebro (BDNF) na BLA e no hipocampo referentes à consolidação da memória. Resultados: Os resultados demonstraram que a infusão intra-amigdalar de TSA 1.5 h, 3 h e 6 h após o treino na tarefa de esquiva inibitória resulta na melhora da memória de longa duração (LTM). TSA acelerou a extinção da memória quando infundido imediatamente pós-teste. Além disso, aumentou os níveis de BDNF no hipocampo. Conclusão: Estes resultados indicam que eventos epigenéticos possuem um papel importante no aprendizado e na memória através da atividade de HDACs. / Introduction: Memory formation involves changes in the expression of neuronal genes. Epigenetic remodeling of chromatin and reversible post-translational modifications in the DNA or in the histone proteins represent central mechanisms in the regulation of gene expression during brain development and early learning or memory retrieval. Imbalances in the levels of histone acetylation are associated with a wide variety of brain disorders. Histone deacetylases (HDACs) play a key role in homeostasis of histone acetylation and regulation of fundamental cellular activities, such as transcription, making them a focus of study. Evidences shows that the administration of histone deacetylases inhibitors (HDACis) restore the memory associated with the regulation of gene expression and improves memory in rats. Studies in animal models have shown that memory formation involves a series of biochemical changes in several areas of the central nervous system, which the hippocampus and basolateral amygdala (BLA) are the most highlighted. In this context, experimental drugs, such as trichostatin A (TSA), that act on epigenetic mechanisms, have recently been proposed as potential therapies for the treatment of memory and cognitive dysfunction associated with psychiatric and neurological disorders. Objective: In this work we aimed to understand and elucidate the role of histone acetylation in processes involved in memory modulation using the drug TSA and is based on the hypothesis that HDACs activity is essential for the modulation of learning answers in the inhibitory avoidance (IA) task. Methods: Wistar rats were cannulated bilaterally in the amygdala. The effects of TSA micro-infusions into the BLA were observed in the consolidation and extinction of memory after training in the inhibitory avoidance task and the levels of brain-derived neurotrophic factor (BDNF) in the BLA and hippocampus related to memory consolidation. Results: The results demonstrated that the TSA infusion into BLA 1.5 h , 3 h and 6 h posttraining in the inhibitory avoidance task results in improved long-term memory (LTM). TSA accelerated the extinction of memory when infused immediately post-test. In addition, increased levels of BDNF in the hippocampus. Conclusion: These results indicate that epigenetic events play an important role in learning and memory by HDAC activity.
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Measuring the effect of cathodic protection on the performance of thermally sprayed aluminium coatings at elevated temperature / Avaliação do efeito da proteção catódica no desempenho do revestimento de alumínio pulverizado termicamente submetido a altas temperaturas

Cé, Nataly Araújo January 2017 (has links)
Alumínio Pulverizado Termicamente (TSA) é amplamente utilizado em instalações offshore como revestimento de ânodo de sacrifício em tubulações de aço carbono. O transporte e a instalação desses componentes podem levar a pequenos danos no revestimento, o que pode expor a superfície do aço à água do mar. Sabe-se que o depósito calcário é formado na superfície do aço polarizado catodicamente. Assim, esta pesquisa avaliou o TSA aplicado por sistema de pulverização de arco duplo (TWAS) no aço ao carbono S355J2 + N quando ocorrem danos (holidays) para estudar a formação de depósitos calcários no aço e adquirir dados sobre o desempenho do TSA sob altas temperaturas. A aplicação de diferentes condições também foi considerada: presença de selantes; liga do revestimento (99,5% de Al e Al-5% de Mg) e condições enterradas/não enterradas. Dois tipos de experimentos foram realizados: i) testes em potencial livre sob temperaturas constantes (30, 60 e 90°C) e diferentes tamanhos de holidays (expondo 5, 10 e 20% da superfície do aço) e ii) testes sob gradient térmico onde óleo a ~125°C foi adicionado em uma torre polimérica e água externa a ~10°C ficou em contato com a superfície das amostras (tanto potencial livre como polarização de -950 mVAg/AgCl foram aplicados). Análises incluíram inspeção visual, microscópio eletrônico de varredura e difração de Raio-X. A partir dos testes em temperaturas constante, o TSA atingiu um bom potencial de proteção (-800 a -900 mVAg/AgCl) e pouca diferença nos resultados devido à diferença na composição doTSA e no tamanho do holiday foi observada. As taxas de corrosão foram mantidas entre 0,02 e 0,01 mm/ano. No ensaio sob gradiente térmico e potencial livre, a perda de revestimento e as taxas de corrosão foram de 0,4 a 0,002 mm/ano. Além disso, o potencial alcançado foi de uma faixa menor do que a obtida anteriormente (-745 a -835 mVAg/AgCl). No entanto, quando o TSA foi combinado com proteção catódica externa e gradiente térmico, a espessura do TSA foi satisfatório e as taxas de corrosão obtidas foram inferiores a 0,076 mm/ano. O depósito calcário formado no holiday protegeu o aço contra a corrosão e seu mecanismo de crescimento baseado nesta pesquisa foi construído. / Thermally Sprayed Aluminium (TSA) is widely used in offshore facilities as sacrificial anode coating for carbon-steel risers and pipelines. Transportation and installation of those components can lead to small damages in the coating, which can expose the steel surface to the seawater. It is known that calcareous deposit is formed on the cathodically polarised steel surface. Thus, this research evaluated the TSA applied by twin wire arc spray system (TWAS) on S355J2+N carbon-steel when damage (holidays) is present in order to study the calcareous deposit formation on steel and acquire data regarding the TSA performance at high temperatures. Application of different conditions was also considered: presence of sealing; coating alloy (99.5%Al and Al-5%Mg) and buried/unburied conditions. Generally, two types of experiment were conducted – i) tests at free potential at steady temperatures (30, 60 and 90°C) and different holiday sizes (exposing 5, 10 and 20% of the steel surface) and ii) tests under thermal gradient where oil at ~125°C was added in polymeric tower and external water at ~10°C was in contact with the samples surface (both free potential and polarisation of -950 mVAg/AgCl were applied). Methodology of analyses included visual inspection, scanning electron microscope and X-ray Diffraction. From the tests at steady temperatures, the TSA reached a very good protective potential (-800 to -900 mVAg/AgCl) and little difference in results due to difference in TSA composition and holiday size was observed. Corrosion rates were kept between 0.02 and 0.01 mm/year. From the thermal gradient test under free potential, the coating loss and corrosion rates were 0.4 to 0.002 mm/year. Also, the potential achieved was in a lower range than previously obtained (-745 to -835 mVAg/AgCl). However, when TSA was combined with external cathodic protection and thermal gradient, the thickness of the TSA was satisfactory and corrosion rates obtained were below 0.076 mm/year. The calcareous deposit formed within the holiday protected the steel substrate against corrosion and its growth mechanism based in this research was built.

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