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Influence of ionic strength on the properties of ionic amphiphilic pairs
Filipová, Lenka ; Smilek, Jiří (referee) ; Mravec, Filip (advisor)
The Bachelor thesis studies catanionic vesicle systems consisting of ion pair amphiphile (IPA) and their properties in the presence of ionic strength. Ion pair amphiphile was prepared from single-chained surfactants: cationic surfactant HTMAB (hexadecyltrimethylammonium bromide) and anionic surfactant SDS (sodium lauryl sulfate). Cationic double-chained surfactant DDAC (dimethyldioctadecylammonium chloride) was added in order to stabilize the vesicle system and make it positively charged. Cholesterol was also added to further stabilize the vesicle system. The system is considered to be relatively stable when consisting of 90 % IPA and 10 % DDAC with 43 mol.% cholesterol in a membrane. The stability of the system can be disrupted by external factors such as ionic strength. The Ionic strength was induced by NaCl solutions of varying concentrations (0.0, 0.5, 1.0, 2.0, 50.0, 100.0, 150.0 and 300.0 mM). The change of properties of a vesicle system, which was induced by ionic strength, was analyzed by electrophoretic and dynamic light scattering, fluorescence anisotropy, and generalized polarization. –potential was obtained by electrophoretic light scattering analysis which determines the stability of the system. Dynamic light scattering measurement resulted in the determination of the size of vesicles. The fluidity of vesicles’ membranes was examined by fluorescence anisotropy with DPH (1,6-diphenyl-1,3,5-hexatriene) as a probe. The hydration shell of vesicles was observed by generalized polarization with Laurdan (2-(dimethylamino)-6-dodecanoylnaphthalene) as a probe. As a result, it was found out that low ionic strength (0.5 to 2.0 mM) causes a decrease in the size of vesicles and high ionic strength (50.0 to 300.0 mM) causes vesicles to grow in size. –potential showed a consistent trend for the whole concentration series – its value rapidly decreasing with increasing ionic strength. The samples with the concentrations of salt 50.0 to 300.0 mM were considered unstable according to the –potential data. Fluorescence anisotropy decreases with increasing temperature and increasing ionic strength. The value of generalized polarization decreases with increasing temperature; hence there is more solvation of a vesicle membrane. The highest value of generalized polarization was measured when the concentration of sodium chloride was relatively high (from 50.0 to 300.0 mM), as a result of which the membrane was less hydrated and therefore, more organized.
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Modernity and the Holocaust
Harlenderová, Eva ; Štojdl, Václav (referee) ; Rozwalka, Szymon (advisor)
The diploma thesis builds on the knowledge gained during the preparation of the pre-diploma thesis in the previous semester. The main outputs for the thesis were the book Modernity and the Holocaust by the Polish sociologist Zygmund Bauman and the concept of „otherness“ defined by the architect Peter Eisenman when designing the Jewish Memorial in Berlin. On the basis of these findings, I prepared maps that dealt with otherness from the perspective of majority and minority societies and maps of the spread of the Jewish community in the city of Brno, which I subsequently based my diploma project on. The task of the diploma project is to design a Holocaust Documentation Centre in Moravia on a predetermined plot of land in Brno. A closed architectural competition was announced for this project. In the design of the above mentioned building, I try to capture the fluidity and changeability of the human community through the architectural language. I think of human society as a continuity and fluidity of individual cultures defined as minority and majority societies. Through architecture I try to express the intermingling, fluidity and instability of the hierarchy of minority and majority communities. In doing so, I create ambiguously dominant and submissive spaces. From one place a space may appear submissive, whereas from another it may appear more dominant.
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Effect of surfactin on the lipid moiety of Bacillus subtilis cytoplasmic membrane
Sklenářová, Petra ; Seydlová, Gabriela (advisor) ; Lichá, Irena (referee)
Surfactin, a secondary metabolite produced by Bacillus subtilis, is a surface active compound and antibiotic permeabilizing membrane bilayer. The aim of this study was to reveal the self-resistance strategy at the level of the lipid moiety of cytoplasmic membrane, which B. subtilis employs to combat surfactin in concentrations that are lethal for other bacterial species. Non-producing strain B. subtilis 168 was cultivated in the presence of two different sublethal concentrations of surfactin (350 a 650 µg/ml), which was isolated from the culture broth of B. subtilis ATCC 21332. Presence of surfactin in the medium resulted in a concentration dependent lag phase, which took 40 min (350 µg/ml) and 3 h (650 µg/ml), respectively. Afterwards, the culture grew with the altered doubling time of 44 min (350 µg/ml) and 126 min (650 µg/ml), respectively. Surfactin induced substantial changes in the phospholipid composition of the cytoplasmic membrane. The proportion of the major phospholipid component phosphatidylglycerol decreased and inversely, the level of phosphatidylethanolamine increased. Interestingly, the content of phosphatidic acid rose considerably in the presence of surfactin concentration causing stimulation of B. subtilis growth (350 µg/ml). Liposome leakage assay using phospholipids mimicking...
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Bicy-colonization: A symmetrical ethnography of the development project Kola pro Afriku (Czech Bikes for Gambian Schools)
Werner, Jan ; Stöckelová, Tereza (advisor) ; Brož, Luděk (referee)
This study is a symmetrical ethnography of the Czech development project Kola pro Afriku (Czech Bikes for Gambian Schools), which involves the collection, repairs, modification and shipment of old Czech bicycles to The Gambia. Once there, they are distributed to partner schools and offered to communing pupils. In my research, I mainly focus on the pivotal technology of the project, bicycles, and their performances. Drawing on classic ethnographies of development and (most importantly) on studies based on the actor-network theory (ANT), I gradually explore the bike collection process, their modifications and repairs, their shipment to The Gambia and their local operations. When doing so, I focus on the social topology of the bicycles and its transformations in the timespace. In this regard, the bicycles gradually appear as junk (i.e. a dysfunctional relict of stabilized networks), as a fluid collectivity and as individually fluid. Thereby, this study shows that technology transfers may lead not only to changes in the set of relations, of which the given object consists, but in the very modes, in which those relations arise. It is precisely these topological transformations that significantly contribute to the functioning of the project Kola pro Afriku. Key words: development cooperation,...
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Influence of ionic strength on the properties of ionic amphiphilic pairs
Filipová, Lenka ; Smilek, Jiří (referee) ; Mravec, Filip (advisor)
The Bachelor thesis studies catanionic vesicle systems consisting of ion pair amphiphile (IPA) and their properties in the presence of ionic strength. Ion pair amphiphile was prepared from single-chained surfactants: cationic surfactant HTMAB (hexadecyltrimethylammonium bromide) and anionic surfactant SDS (sodium lauryl sulfate). Cationic double-chained surfactant DDAC (dimethyldioctadecylammonium chloride) was added in order to stabilize the vesicle system and make it positively charged. Cholesterol was also added to further stabilize the vesicle system. The system is considered to be relatively stable when consisting of 90 % IPA and 10 % DDAC with 43 mol.% cholesterol in a membrane. The stability of the system can be disrupted by external factors such as ionic strength. The Ionic strength was induced by NaCl solutions of varying concentrations (0.0, 0.5, 1.0, 2.0, 50.0, 100.0, 150.0 and 300.0 mM). The change of properties of a vesicle system, which was induced by ionic strength, was analyzed by electrophoretic and dynamic light scattering, fluorescence anisotropy, and generalized polarization. –potential was obtained by electrophoretic light scattering analysis which determines the stability of the system. Dynamic light scattering measurement resulted in the determination of the size of vesicles. The fluidity of vesicles’ membranes was examined by fluorescence anisotropy with DPH (1,6-diphenyl-1,3,5-hexatriene) as a probe. The hydration shell of vesicles was observed by generalized polarization with Laurdan (2-(dimethylamino)-6-dodecanoylnaphthalene) as a probe. As a result, it was found out that low ionic strength (0.5 to 2.0 mM) causes a decrease in the size of vesicles and high ionic strength (50.0 to 300.0 mM) causes vesicles to grow in size. –potential showed a consistent trend for the whole concentration series – its value rapidly decreasing with increasing ionic strength. The samples with the concentrations of salt 50.0 to 300.0 mM were considered unstable according to the –potential data. Fluorescence anisotropy decreases with increasing temperature and increasing ionic strength. The value of generalized polarization decreases with increasing temperature; hence there is more solvation of a vesicle membrane. The highest value of generalized polarization was measured when the concentration of sodium chloride was relatively high (from 50.0 to 300.0 mM), as a result of which the membrane was less hydrated and therefore, more organized.
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Bicy-colonization: A symmetrical ethnography of the development project Kola pro Afriku (Czech Bikes for Gambian Schools)
Werner, Jan ; Stöckelová, Tereza (advisor) ; Brož, Luděk (referee)
This study is a symmetrical ethnography of the Czech development project Kola pro Afriku (Czech Bikes for Gambian Schools), which involves the collection, repairs, modification and shipment of old Czech bicycles to The Gambia. Once there, they are distributed to partner schools and offered to communing pupils. In my research, I mainly focus on the pivotal technology of the project, bicycles, and their performances. Drawing on classic ethnographies of development and (most importantly) on studies based on the actor-network theory (ANT), I gradually explore the bike collection process, their modifications and repairs, their shipment to The Gambia and their local operations. When doing so, I focus on the social topology of the bicycles and its transformations in the timespace. In this regard, the bicycles gradually appear as junk (i.e. a dysfunctional relict of stabilized networks), as a fluid collectivity and as individually fluid. Thereby, this study shows that technology transfers may lead not only to changes in the set of relations, of which the given object consists, but in the very modes, in which those relations arise. It is precisely these topological transformations that significantly contribute to the functioning of the project Kola pro Afriku. Key words: development cooperation,...
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Effect of surfactin on the lipid moiety of Bacillus subtilis cytoplasmic membrane
Sklenářová, Petra ; Seydlová, Gabriela (advisor) ; Lichá, Irena (referee)
Surfactin, a secondary metabolite produced by Bacillus subtilis, is a surface active compound and antibiotic permeabilizing membrane bilayer. The aim of this study was to reveal the self-resistance strategy at the level of the lipid moiety of cytoplasmic membrane, which B. subtilis employs to combat surfactin in concentrations that are lethal for other bacterial species. Non-producing strain B. subtilis 168 was cultivated in the presence of two different sublethal concentrations of surfactin (350 a 650 µg/ml), which was isolated from the culture broth of B. subtilis ATCC 21332. Presence of surfactin in the medium resulted in a concentration dependent lag phase, which took 40 min (350 µg/ml) and 3 h (650 µg/ml), respectively. Afterwards, the culture grew with the altered doubling time of 44 min (350 µg/ml) and 126 min (650 µg/ml), respectively. Surfactin induced substantial changes in the phospholipid composition of the cytoplasmic membrane. The proportion of the major phospholipid component phosphatidylglycerol decreased and inversely, the level of phosphatidylethanolamine increased. Interestingly, the content of phosphatidic acid rose considerably in the presence of surfactin concentration causing stimulation of B. subtilis growth (350 µg/ml). Liposome leakage assay using phospholipids mimicking...
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