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L'objectif principal de cette thèse est la formulation des mélanges stables contenant l'hydroxyapatite gel synthétisée (Ca-HAGel). Le comportement rhéologique des mélanges Eau/(sulfate de calcium) et hydroxyapatite/(sulfate de calcium) a été étudié. Les résultats ont montré que tout les mélanges sont caractérisés par un comportement rhéologique rhefluidifiant et thixotrope. Le potentiel zeta a été utilisé dans cette étude pour mieux appréhender les interactions entre les particules et leur effet sur le comportement des mélanges. La fixation de sulfate sur la surface de Ca- HA favorise la stabilité de la structure du Ca-HAGel. Les analyses de caractérisation effectuées sur les formulations ont montré la formation de nouveaux composés tels que le sulfate-phosphate de calcium hydrate et l'Ardealite. Les tests de lixiviation et de percolation ont révélé que le taux de relargage de soufre et strontium à partir des sous-produits de gypse était négligeable pour les mélanges contenant Ca-HAGel. Ca- HAGel stabilise les métaux lourds relargués à partir du gypse et plâtre. Les particules du gypse améliorent les performances hydrauliques de Ca-HAGel et le plâtre hydraté stabilise la structure de Ca-HAGel par la formation des particules agglomérées. Le test colonne effectué sur la formulation AWPG2 a montré une grande performance à retenir le plomb et le cadmium avec des capacités de rétention de plus de 99% et 88% respectivement. Le traitement des métaux lourds était lié aux particules de Ca-HA et aux phosphate et calcium libres. La formulation AWPG2 peut être utilisée dans les barrières perméables réactives pour traiter les eaux souterraines contaminées. / The main purpose of this thesis was the formulation of stable blends based on synthesized hydroxyapatite-gel (Ca-HAGel). The rheological behavior of water−calcium sulfates and hydroxyapatite−calcium sulfates blends was considered in this study. The results show that all blends and formulations exhibit a shearthinning effect and thixotropic behavior. The ζ potential was used in this study to understand the interaction between particles and its effect on the global behavior of the blends. Fixation of sulfate on Ca-HA surface promotes the stability of Ca-HAGel suspension. Characterization analysis of formulation shown the presence of new compounds such as calcium sulfate-phosphate hydrate and Ardealite. Leaching and percolation tests revealed that the release rate of sulfur and strontium from gypsum by-product was negligible in blends based on Ca- Agel. Ca-HAGel was stabilized the heavy metals released from plaster and gypsum. Gypsum particles enhanced hydraulic performances of Ca-HAGel and hydrated plaster stabilized Ca-HAGel structure by the formation of agglomerated particles. Column test carried out on AWPG2 blend revealed high removal performances for lead and cadmium with retention capacity of 99% and 88% respectively. The reactivity was related to Ca-HA and free calcium and phosphate contained in the selected formulation. AWPG2 blend is to be used as permeable reactive barrier for in-situ contaminated groundwater remediation

Orientador: José Roberto Ruggiero / Banca: Mário Sérgio Palma / Banca: André Farias de Moura / Resumo: Mastoparanos são peptídeos helicoidais, anfipáticos e catiônicos que apresentam diversas funções biológicas, entre elas temos a ação antimicrobiana, que está relacionada à sua afinidade por membranas aniônicas de bactérias e sua capacidade lítica. Recentes estudos têm mostrado que a formação de poros em membranas é facilitada pela agregação de peptídeos carregados. Esta situação favoreceria a hipótese de que a formação de poro é essencialmente similar a eletroporação molecular. Neste trabalho investigamos a estabilidade de um dímero do Eumenine Mastoparan-AF, um membro catiônico (+4) da família dos mastoparanos, em água e mistura TFE-água, mimetizando meio aquoso e meio membranar, respectivamente. Particular atenção foi colocada nas interações eletrostáticas de grupos carregados e polares, principalmente naqueles que participam de ligações de hidrogênio entre os dois peptídeos e na hidratação da cadeia principal e cadeias laterais apolares. Uma estrutura dimérica representativa foi inicialmente obtida por um método de docking rígido e submetida às simulações de dinâmica molecular usando o pacote GROMACS. Resultados de 50 ns de simulação em água mostram uma perda parcial do conteúdo helicoidal dos peptídeos e a estrutura dimérica se desestrutura devido às interações desfavoráveis dos resíduos hidrofóbicos com a água. Por outro lado, simulações em mistura TFE-água mostram que o dímero é estável durante o tempo observado, porque as moléculas de TFE se agrupam ao redor de resíduos hidrofóbicos criando um meio apropriado que protege as ligações de hidrogênio intra- e inter-peptídeos. Surpreendentemente, parece que a repulsão eletrostática não é a principal razão para a desagregação do dímero, o que reforça a importância da. / Abstract: Mastoparans are helical, amphipathic and cationic peptides that display many biological functions, among which is the antimicrobial activity, which is related to its affinity for anionic membranes of bacteria and its lytic capacity. Recent studies have shown that pore formation on membranes is facilitated by the aggregation of charged peptides. This situation would favor the hypothesis that pore formation is essentially similar to the molecular electroporation. In this work, we investigate the stability of a dimer of the Eumenine Mastoparan-AF, a cationic (+4) member of the Mastoparan family, in water and TFE-water mixture, mimicking aqueous and membrane environments, respectively. Particular attention have been put on the electrostatic interactions of charged and polar groups, mainly those participating of hydrogen bonds between the two peptides and on the hydration of the backbone and apolar side chains. A representative dimer conformation was initially obtained by a rigid docking procedure and submitted to molecular dynamics simulations using the GROMACS package. Results of 50 ns of simulation in water show a partial loose of the helical content of the peptides and the dimer structure breaks down due to unfavorable interactions of hydrophobic residues with water. On the other hand, simulations in TFE-water mixture show the dimer is stable in the running time, because TFE molecules assemble around hydrophobic residues creating a suitable environment that protect the intra- and inter-peptides hydrogen bonds. Surprisingly, it seems that electrostatic repulsion is not the main reason for disaggregation of the dimer what reinforces both the importance of aggregation and the molecular electroporation mechanism for pore formation. / Mestre

Made available in DSpace on 2014-06-11T19:22:54Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-03-22Bitstream added on 2014-06-13T18:49:56Z : No. of bitstreams: 1 lopesfilho_fc_me_sjrp.pdf: 770782 bytes, checksum: 9373005f0d61b57eee8eaf4f430acc27 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Mastoparanos são peptídeos helicoidais, anfipáticos e catiônicos que apresentam diversas funções biológicas, entre elas temos a ação antimicrobiana, que está relacionada à sua afinidade por membranas aniônicas de bactérias e sua capacidade lítica. Recentes estudos têm mostrado que a formação de poros em membranas é facilitada pela agregação de peptídeos carregados. Esta situação favoreceria a hipótese de que a formação de poro é essencialmente similar a eletroporação molecular. Neste trabalho investigamos a estabilidade de um dímero do Eumenine Mastoparan-AF, um membro catiônico (+4) da família dos mastoparanos, em água e mistura TFE-água, mimetizando meio aquoso e meio membranar, respectivamente. Particular atenção foi colocada nas interações eletrostáticas de grupos carregados e polares, principalmente naqueles que participam de ligações de hidrogênio entre os dois peptídeos e na hidratação da cadeia principal e cadeias laterais apolares. Uma estrutura dimérica representativa foi inicialmente obtida por um método de docking rígido e submetida às simulações de dinâmica molecular usando o pacote GROMACS. Resultados de 50 ns de simulação em água mostram uma perda parcial do conteúdo helicoidal dos peptídeos e a estrutura dimérica se desestrutura devido às interações desfavoráveis dos resíduos hidrofóbicos com a água. Por outro lado, simulações em mistura TFE-água mostram que o dímero é estável durante o tempo observado, porque as moléculas de TFE se agrupam ao redor de resíduos hidrofóbicos criando um meio apropriado que protege as ligações de hidrogênio intra- e inter-peptídeos. Surpreendentemente, parece que a repulsão eletrostática não é a principal razão para a desagregação do dímero, o que reforça a importância da. / Mastoparans are helical, amphipathic and cationic peptides that display many biological functions, among which is the antimicrobial activity, which is related to its affinity for anionic membranes of bacteria and its lytic capacity. Recent studies have shown that pore formation on membranes is facilitated by the aggregation of charged peptides. This situation would favor the hypothesis that pore formation is essentially similar to the molecular electroporation. In this work, we investigate the stability of a dimer of the Eumenine Mastoparan-AF, a cationic (+4) member of the Mastoparan family, in water and TFE-water mixture, mimicking aqueous and membrane environments, respectively. Particular attention have been put on the electrostatic interactions of charged and polar groups, mainly those participating of hydrogen bonds between the two peptides and on the hydration of the backbone and apolar side chains. A representative dimer conformation was initially obtained by a rigid docking procedure and submitted to molecular dynamics simulations using the GROMACS package. Results of 50 ns of simulation in water show a partial loose of the helical content of the peptides and the dimer structure breaks down due to unfavorable interactions of hydrophobic residues with water. On the other hand, simulations in TFE-water mixture show the dimer is stable in the running time, because TFE molecules assemble around hydrophobic residues creating a suitable environment that protect the intra- and inter-peptides hydrogen bonds. Surprisingly, it seems that electrostatic repulsion is not the main reason for disaggregation of the dimer what reinforces both the importance of aggregation and the molecular electroporation mechanism for pore formation.

Eurokoderna som utgör svenska normer för verifiering av bärförmåga, stadga och beständighet är i en fortgående utvecklingsfas och är ibland svåra och tidsödande att tillämpa i konstruktionsarbetet. Normerna anpassas kontinuerligt efter att frågor debatteras i branschen och det är viktigt att användarna av Eurokoderna håller sig uppdaterade. Svårtolkade begrepp och definitioner tillsammans med en omständig struktur i Eurokoderna skapar merarbete för användarna. Detta examensarbete sammanställer nödvändig information samt undersöker och utvecklar tillhörande begrepp för två ämnen, lastnedräkning och stomstabilitet. Examensarbetet kommer likt en handbok kunna användas i vardagligt konstruktörsarbete för att snabbt hitta rätt i Eurokoderna och bidra till att reda ut oklarheter kring de två berörda ämnena. Beräkningsexempel är upprättade som praktisk vägledning för respektive ämne där Eurokoderna tillämpas och hänvisas till. Examensarbetet är inriktat på handberäkningar. Dessa handberäkningar kan ligga till grund för initiala bedömningar av ett bärverks dimensioner och övergripande stabilitet men även vara ett stöd i beräkningar i bygghandlingsskeden. / The Eurocodes, which serve as the Swedish standards for verification of mechanical resistance and stability, are in an ongoing development phase and are sometimes difficult and time consuming to apply in the design process. The standards are continuously adapted to issues debated in the industry and it is important that users of the Eurocodes keep themselves up to date. Indistinct terms and definitions in the Eurocodes create, together with an inconvenient structure, extra work for users. This thesis compiles the necessary information and examines and elaborates terms related to two topics, load distribution and structure stability. Similar to a handbook, this thesis can be used in designer’s everyday work to quickly find the right Eurocodes and help sort out the confusion related to the topics in this thesis. Calculation examples are given as a practical guide where Eurocodes are applied and referred to. The thesis is focused on hand calculations. These hand calculations could act as a base for initial assessments concerning structure dimensions and overall stability as well as a guide during final calculations for construction drawings.

This thesis deals with the combined ultra-high vacuum (UHV) and electrochemical (EC) studies of selected iron oxide surfaces, namely Fe3O4(001) and -Fe2O3(012). The state-of- the-art knowledge regarding these surfaces is briefly reviewed, and importance of understanding these materials in the electrochemical environment is discussed. The design of the transfer system between UHV and EC environment is presented; individual features of the system are thoroughly discussed and the system is used for testing the stability of the Fe3O4(001) (2×2)R45° surface reconstruction in ambient conditions. The experimental results presented in this thesis show that the Fe3O4(001) (2×2)R45° reconstruction, utilized as an adatom array for single atom catalysis studies, survives both exposure to air and to liquid water, if the exposure is achieved in well-controlled fashion. Further, this thesis presents the first-ever atomic scale scanning tunneling microscopy (STM) study of the -Fe2O3(012) surface, which is important for photoelectrochemical water splitting. STM images of two surface reconstructions of the -Fe2O3(012) surface known to date are presented. A bulk terminated model of the (1×1) reconstruction is confirmed and a novel surface structure model for the (2×1) reconstructed surface is proposed. Adsorption studies of H2O and O2 on the (2×1) reconstructed surface are documented by timelapse STM.

The master‘s thesis deals with the influence of the thermal cycle of welding with preheat on castings made of grey cast iron to change the hardness. The thesis deals with the classification of graphitic cast irons, their structure, properties and influences they have on the formation and transformation of the structure. Emphasis is placed on chemical composition and structure stability at elevated temperatures. The practical part deals with the investigation of the effects of casting repair on the decrease of hardness measured in the foundry Heunisch Brno.