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Study of alkali metals ions diffusion in hardened cement
Doležal, Martin ; Janča, Martin (referee) ; Šoukal, František (advisor)
This master thesis is aim to study alkali diffusion (sodium, potassium) in hardened cement paste body. It´s deal with impact of various sorroudings (hydroxide, nitrate and carbonate) in various concentrations and temperature effect. This work is also deal with changes in cement paste and medium. Teoretic part is talking about cement production and cement chemistry, alkali-silica reaction, plasticizer, diffusion an cement testing metods. This work is aimed to white (Aalborg CEM I 52,5 R – SR 5) and road (Mokrá CEM I 42,5 R – sc) cement. Experimental part describes constitution of tested cement pastes, conservation of them and sampling. Diffusion is study by ICP-AES which affected the loss of alkali from the solution and SEM which affected alkali migration (diffusion) in cement paste. In several cases, the formation of a saturated alkali edge was observed, followed by steady diffusion. In the case of potassium there was very slow diffusion through the body mass. The influence of medium and temperature was evaluated as the most significant. The effect of medium concentration wasn´t significant. Also changes in the porosity on the body were observed. The diffusion itself was affected by secondary products gorwing on the surface of body and in the medium. The work deals with them in the last part.
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Bacterial toxins acting on biological membranes
Benešová, Anna ; Fišer, Radovan (advisor) ; Sýkora, Jan (referee)
Colicin E1 is a bacterial toxin, which has been researched for a long time and belongs to a group of pore-forming colicins. Pore-forming colicins act on cytoplasmic membranes of sensitive cells. They form ionophoric channels, which can depolarize the membrane and kill the cell. Colicins in general can be considered as a tool used by related bacterial strains of Escherichia coli and other Enterobacteriaceae to compete for resources. Recently, a hypothesis emerged that colicin E1 is not a tool for killing related bacterial strains but rather a tool for killing human cells by uropathogenic strains of Escherichia coli. So far, colicin E1 was described inaccurately, together with its different sequence variant - newly described colicin E11. Colicin E11 could have evolved as a weapon against other bacteria of gut microbiota. The aim of this thesis was to compare the pore-forming abilities of colicins E1 and E11 by measurements on planar lipid membranes and liposomes of various lipid compositions. Based on results it seems that both colicins form channels of comparable conductance and they are both mildly cation-selective. Measurements on liposomes showed higher activity for colicin E1 compared to colicin E11 on membranes mimicking both mammalian and Gram-negative bacterial cytoplasmic membrane. Results...
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Elucidation of the properties and structure of the pore-forming domain of colicin U produced by bacterium Shigella boydii.
Dolejšová, Tereza
Colicin U is a protein produced by bacterium Shigella boydii. It belongs to the group of pore-forming colicins. These colicins interact with receptors in the outer membrane of bacteria closely related to a producing colicinogenic strain. After interaction with the receptor, colicin is translocated across the outer membrane and periplasm to the cytoplasmic membrane where it forms pores. Consequently, the pore formation leads to membrane depolarization and cell death. In this thesis I decided to study the pore-forming properties of colicin U and its membrane topology. It is shown that colicin U pores are formed by only one colicin molecule and they are voltage dependent. Using measurements with nonelectrolytes we estimated a theoretical inner profile of the pore and its inner diameter to be between 0.7 and 1 nm. Above that, a membrane topology of colicin U pore-forming domain (PFD) is studied. BLM measurements with biotinylated colicin U showed that a significant part of colicin's PFD was translocated to the opposite side of the membrane after the pore opening. The segment between substituted amino acids F463 and D486 was evidenced to be on the trans side of the membrane after the pore opening. Additionally, properties of peptide H1, which reflects a significant part of the first α- helix of colicin...
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Elucidation of the properties and structure of the pore-forming domain of colicin U produced by bacterium Shigella boydii.
Dolejšová, Tereza ; Fišer, Radovan (advisor) ; Krůšek, Jan (referee) ; Osička, Radim (referee)
Colicin U is a protein produced by bacterium Shigella boydii. It belongs to the group of pore-forming colicins. These colicins interact with receptors in the outer membrane of bacteria closely related to a producing colicinogenic strain. After interaction with the receptor, colicin is translocated across the outer membrane and periplasm to the cytoplasmic membrane where it forms pores. Consequently, the pore formation leads to membrane depolarization and cell death. In this thesis I decided to study the pore-forming properties of colicin U and its membrane topology. It is shown that colicin U pores are formed by only one colicin molecule and they are voltage dependent. Using measurements with nonelectrolytes we estimated a theoretical inner profile of the pore and its inner diameter to be between 0.7 and 1 nm. Above that, a membrane topology of colicin U pore-forming domain (PFD) is studied. BLM measurements with biotinylated colicin U showed that a significant part of colicin's PFD was translocated to the opposite side of the membrane after the pore opening. The segment between substituted amino acids F463 and D486 was evidenced to be on the trans side of the membrane after the pore opening. Additionally, properties of peptide H1, which reflects a significant part of the first α- helix of colicin...
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Study of alkali metals ions diffusion in hardened cement
Doležal, Martin ; Janča, Martin (referee) ; Šoukal, František (advisor)
This master thesis is aim to study alkali diffusion (sodium, potassium) in hardened cement paste body. It´s deal with impact of various sorroudings (hydroxide, nitrate and carbonate) in various concentrations and temperature effect. This work is also deal with changes in cement paste and medium. Teoretic part is talking about cement production and cement chemistry, alkali-silica reaction, plasticizer, diffusion an cement testing metods. This work is aimed to white (Aalborg CEM I 52,5 R – SR 5) and road (Mokrá CEM I 42,5 R – sc) cement. Experimental part describes constitution of tested cement pastes, conservation of them and sampling. Diffusion is study by ICP-AES which affected the loss of alkali from the solution and SEM which affected alkali migration (diffusion) in cement paste. In several cases, the formation of a saturated alkali edge was observed, followed by steady diffusion. In the case of potassium there was very slow diffusion through the body mass. The influence of medium and temperature was evaluated as the most significant. The effect of medium concentration wasn´t significant. Also changes in the porosity on the body were observed. The diffusion itself was affected by secondary products gorwing on the surface of body and in the medium. The work deals with them in the last part.
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