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Utsläpp av CO2 till atmosfären bidrar till ökningen av globala temperaturer. Industrisektorn står för 20 % av utsläppen och utav dessa kommer 6 % från pappers- och massaindustrin. För att lyckas minska den globala temperaturhöjningen till under 1,5 °C hjälper det inte bara att minska utsläppen. Även negativa utsläpp måste genereras. Syftet med denna studie är att undersöka implementeringen av CLG för att separera CO2 på ett energieffektivt sätt och samtidigt generera H2 och elektricitet. Processanalyser genomfördes för att undersöka möjligheten att implementera CLG-processen till ett typiskt massabruk. Processmodeller togs fram for att undersöka CLG, värmeåtervinning samt elektricitetsgenerering. Processmodellerna utvecklades med hjälp av Aspen Plus och Aspen HYSYS. De framtagna modellerna analyserades sedan med avseende på olika designparametrar inom CLG-processen. På ett typiskt massabruk som producerar 800 000 adt varje ˚ar kan 375 kg CO2/adt separeras och då uppnå negativa utsläpp, genom att byta ut multi-fuel forsrännaren med en CLG process. Den framtagna processmodellen skulle också kunna generera 360-504 kWh/adt av H2 beroende på de designparametrar som används för CLG-processen. Enligt modellen kan värme som ˚återvinns från processen användas för att fånga upp ytterligare 13 % av CO2 från andra delar av bruket. Processanalys för olika designparametrar inom CLG systemet så som temperatur, luftflöde och flödet av syrgasbärare har presenterats. Nyckeltalen som undersöktes var den mängd CO2 som kunde fångas upp, mängd H2 genererad samt överskottet av elektricitet som produceras när multi-fuel förbränningen byts ut mot en CLG-process på ett typiskt massa bruk. / Emissions of CO2 to the atmosphere are contributing to the global temperature rise. The industrial sector contributed to 20 % of the emissions and out of that, 6 % are generated from the pulp and paper industry. To limit the temperature increase below 1,5 °C, the emissions not only need to be reduced but also negative emissions should be generated from different sectors. The purpose of this study is to realize the implementation of Chemical Looping Gasification (CLG) to separate CO2 (for permanent storage) in an energy-efficient way while co-generating H2 as well as electricity. Process analysis was carried out to investigate the possibility of substituting the multifuel boiler in a typical pulp mill with a CLG process. Process models for the CLG, heat recovery and electricity generation process were developed using Aspen  Plus and Aspen HYSYS. The process was analysed for different design conditions (temperature, autothermal condition, air flow, oxygen carrier flow) in the CLG process. It was found that in a typical pulp mill producing 800 000 adt per year, 375 kg- CO2/adt (14 % of total emissions from the process) can be inherently separated for storage to achieve negative emissions, if the multi-fuel boiler is replaced with a CLG unit. This process will also be able to generate 360-504 kWh/adt H2 depending on the design conditions in the CLG process. Heat recovered from the CLG unit can be utilized in capturing approximately 13 % additional CO2 from other sources in the pulp mill. Process analysis for different design conditions in CLG (temperature, airflow, oxygen carrier flow) have been presented. The key performance indicators were CO2 capture rates, H2 generated and net electrical output from the process.

<p>Gene expression is a complex process by which genetic information flow from genes to proteins. Factors regulating gene expression are diverse ranging from sequence elements on DNA, to various types of RNA, to proteins. These factors are categorized into two main categories, <em>cis</em>-acting elements and <em>trans</em>-acting elements. <em>PHO84</em> is a budding yeast gene that was previously reported to be regulated by its cognate antisense transcripts both in <em>cis</em> and in <em>trans</em>. The antisense transcripts of <em>PHO84</em> are a group of long non-coding RNAs (lncRNAs). In my project, I performed RNA-seq and TT-seq analysis to investigate the global correlation of sense/antisense pairs, which showed that the model of sense/antisense negative correlation is not always true for <em>PHO84</em> locus as well as others. I conducted a series of gene expression analysis experiments to decipher the mechanisms regulating <em>PHO84</em> gene, which showed that the 3’ untranslated region (3’UTR) of <em>PHO84</em> plays a regulatory role in the sense expression, an activity not linked to the antisense transcript levels. I also performed a genetic screen to identify <em>trans</em>-acting protein factors that promote the 3’UTR-dependent regulation at <em>PHO84</em> locus.</p> <p>Taken together, I provided insights on both <em>cis</em>- and <em>trans</em>-acting elements controlling the expression of the model gene <em>PHO84</em>. Such information can be taken further and be applied to other higher organisms, with possible implication in the identification of key players in human diseases arising from gene expression dysregulation. </p>

(in English): The aim of the work is to reconstruct and interpret the method of historicized analysis and its employment to examine the phenomenon of "making up people". The concept is Hacking's description for the impact scientific classifications can have on classified people. The point of departure for the examination in the work is the thesis that historicized analysis employs the elements of philosophical conceptual analysis together with historical tools philosophy of science corroborates and whose strategies are often in opposition to the analytical tradition. As a follow-up of the main thesis the work also examines whether the historicized analysis can be understood as a history of the present. Moreover, it asks questions that come up in connection with the project of "making up people" such as: "What are the conditions for a scientific category to emerge? When categories emerge do new kinds of people emerge as well? What is the specific structure that enables the mutual interaction and effect scientific categories and classified people make? One of the aims will therefore be to elucidate to what extend the historicized analysis is able to answer those questions. Last but not least the work looks into the critical implications and usefulness of the method of historicized analysis.

Made available in DSpace on 2014-12-17T15:42:13Z (GMT). No. of bitstreams: 1 TiagoRC_DISSERT.pdf: 2194143 bytes, checksum: 2a20949c899c91ba3e574d7f71d319d4 (MD5) Previous issue date: 2012-04-11 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Oxygen carriers are metal oxides which have the ability to oxidize and reduce easily by various cycles. Due to this property these materials are widely usedin Chemical-Looping Reforming processes to produce H2 and syngas. In this work supports based on MCM-41 and La-SiO2 were synthesized by hydrothermal method. After the synthesis step they were calcined at 550?C for 2 hours and characterized by TG, XRD, surface area using the BET method and FTIR spectroscopy. The deposition of active phase, in this case Nickel, took place in the proportions of 5, 10 and 20% by weight of metallic nickel, for use as oxygen carriers.The XRD showed that increasing in the content of Ni supported on MCM-41 resulted in a decrease in spatial structure and lattice parameter of the material. The adsorption and desorption curves of the MCM-41 samples exhibited variations with the increase of Ni deposited. Surface area, average pore diameter and wall density of silica showed significant changes , due to the increase of the active phase on the mesoporous material. By other hand, in the samples with La-SiO2 composition was not observed peaks characteristic of hexagonal structure, in the XRD diffractogram. The adsorption/desorption isotherms of nitrogen observed are type IV, characteristic of mesoporous materials. The catalytic test indicates that the supports have no influence in the process, but the nickel concentration is very important, because the results for minor concentration of nickel are not good. The ratio H2/O2 was close to 2, for all 15 cycles involving the test storage capacity of O2, indicating that the materials are effective for oxygen transport / Transportadores de oxig?nio s?o ?xidos met?licos que possuem a capacidade de oxidar e reduzir facilmente por diversos ciclos. Devido a essa propriedade estes materiais s?o bastante utilizados nos processos de Chemical-Looping Reforming para a produ??o de H2 ou g?s de s?ntese (H2 mais CO). Neste trabalho foram sintetizados os suportes MCM-41 e La-SiO2 pelo o m?todo hidrot?rmico. Os materiais resultantes foram calcinados a 550 ?C por 2 horas e, posteriormente, caracterizados por TG, DRX, ?rea superficial pelo m?todo BET e FTIR. Ap?s a caracteriza??o dos suportes foi feita a deposi??o da fase ativa (Ni) com as propor??es de 5, 10 e 20% em massa de n?quel met?lico, para aplica??o como transportadores de oxig?nio. As an?lises de DRX mostraram que o aumento do teor de Ni suportado em MCM-41 deu origem a uma diminui??o no ordenamento estrutural e no par?metro de rede do material. As amostras MCM-41 apresentaram varia??es quanto ?s curvas de adsor??o/dessor??o de nitrog?nio, ?rea superficial, di?metro m?dio de poros e espessura da parede de s?lica, em fun??o do aumento da fase ativa no material mesoporoso. Enquanto que nas amostras com La-SiO2 n?o se observou picos caracter?sticos da estrutura hexagonal, nos difratogramas de DRX. Entretanto, as curvas de adsor??o/dessor??o de nitrog?nio observadas s?o do tipo IV, caracter?stico de materiais mesoporosos. Os resultados dos testes dos transportadores indicam que o suporte n?o influenciou no processo catal?tico. A raz?o H2/O2 foi pr?xima de 2, durante todos os 15 ciclos envolvendo o teste de capacidade de armazenamento de O2 , indicando que os materiais s?o eficientes para o transporte de oxig?nio estrutural e no par?metro de rede do material. As amostras MCM-41 apresentaram varia??es quanto ?s curvas de adsor??o/dessor??o de nitrog?nio, ?rea superficial, di?metro m?dio de poros e espessura da parede de s?lica, em fun??o do aumento da fase ativa no material mesoporoso. Enquanto que nas amostras com La-SiO2 n?o se observou picos caracter?sticos da estrutura hexagonal, nos difratogramas de DRX. Entretanto, as curvas de adsor??o/dessor??o de nitrog?nio observadas s?o do tipo IV, caracter?stico de materiais mesoporosos. Os resultados dos testes dos transportadores indicam que o suporte n?o influenciou no processo catal?tico. A raz?o H2/O2 foi pr?xima de 2, durante todos os 15 ciclos envolvendo o teste de capacidade de armazenamento de O2 , indicando que os materiais s?o eficientes para o transporte de oxig?nio

Dans cette thèse, des simulations numériques tridimensionnelles instationnaires d'une installation expérimentale de combustion en boucle chimique sont réalisées. Le pilote expérimental, d'une puissance de 120 kWth, utilise un matériau perovskite, à base de Ca-Mn, comme transporteur d'oxygène. Les simulations numériques sont réalisées par le code NEPTUNE_CFD, selon une approche Euler-Euler pour les deux phases (solide et gazeuse), avec des modèles de fermeture spécifiques pour modéliser les transferts de masse, de mouvement et d'énergie. Les réactions hétérogènes (i.e. réactions gaz-solide) de réduction et d'oxydation sont décrites au moyen d'un modèle à cœur rétrécissant dans le grain, qui prend en compte les mécanismes compétitifs dans le processus global de réaction gaz-solide: réaction chimique à la surface interne des particules,diffusion à travers la couche de produits et transfert externe autour des particules. Les résultats des simulations numériques sont validées avec des mesures expérimentales et analysées afin de mieux comprendre le comportement local/instationnaire de l'écoulement gaz-particules réactif dans ce système de combustion en boucle chimique. L'outil théorique/numérique développé dans ce travail sera utilisé pour le dimensionnement d'une unité pilote à l’échelle des installations industrielles. / In this work, reactive unsteady three-dimensional numerical simulations of a Chemical Looping Combustion (CLC) plant are performed. The plant is a 120 kWth pilot working with Ca-Mn-based material as selected oxygen carrier. Numerical simulations are performed by NEPTUNE_CFD code using an Euler-Euler approach which computes both the gas and the solid phases in an Eulerian fashion accounting for specific closures in order to model interphase mass, momentum and energy transfers. Reduction and oxidation heterogeneous (i.e. gas-solid) reactions are modeled by means of a grain model (shrinking core model in the grain) accounting for both the competing mechanisms of chemical reaction at the particle internal surface and gaseous diffusion through the product layer. Results from numerical simulations are validated against experimental measurements and analyzed in order to gain insight in the local behaviour of the reactive gas-particle flow in the CLC system. The theoretical/numerical tool developed in this work will be used for design upgrade recommendation in the stage of scaling-up from pilot to industrial facilities.