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Catanionic vesicular systems
Repová, Romana ; Krouská, Jitka (referee) ; Mravec, Filip (advisor)
This bachelor thesis deals with catanionic vesicles. The aim of the study was to prepare and characterize these systems. The catanionic vesicles are composed of cationic (CTAB, CTAC, TTAB, DTAB) and anionic surfactants (SDS). The physical stability of the vesicles was enhanced with the addition of cationic surfactant DODAC.The catanionic vesicles were characterized by the measurement of the dynamic light scattering, zeta potencial and fluorescence correlation spectroscopy. The size and stability of the system were determined using dynamic light scattering. Difussion coefficient of the system was analyzed using fluorescence correlation spectroscopy.
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Study of Electric and Thermal Properties of Building Materials with Conductive Additives
Veselá, Jana ; Krouská, Jitka (referee) ; Zmeškal, Oldřich (advisor)
This work focuses on study of electric, dielectric and thermal properties of composite electrically conductive building materials composed of magnesium oxychloride cement and small amount of graphene and graphite admixtures. The aim of this work was to determine thermal properties of materials and create a model of electric current conduction mechanism in material. Electric and dielectric properties were determined with using of transient direct current measurement of resistivity and impedance spectroscopy. Thermal properties were investigated using transient step-wise method and fractal analysis of thermocamera data. Electrical resistivities of materials are determined from the direct current measurements. Model of transport of electrical charge carriers was evaluated by fitting impedance data to an equivalent electrical circuit model. Thermal conductivities and thermal capacities were determined by means of thermal measurements. The presented properties for example can be used for assessment of suitability for specific construction applications.
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Interactions of polycations and anionic surfactants
Szabová, Jana ; Krouská, Jitka (referee) ; Mravec, Filip (advisor)
This thesis deals with the study of interaction polycations and anionic sufactants with regard to phase separation in water and in physiological saline solution (0.15 moldm3 NaCl). First, the solubilizing experiments were made (using hydrophobic dye red oil O) for mapping behavior system SDS-DEAE. Then the aggregation behavior of surfactant was measured. Using solubilizing experiments the area for influence of addition dextran hydrochloride for aggregation was selected. This behavior was investigated by fluorescence spectroscopy using pyrene as fluorescence probe. The Critical Micellar and Agregation Concentration of studied system was determined and defined the area of phase separation. The influence of the process of preparing hydrogels by dry or wet path was studeid. The measurements revealed that the addition of salt and polymer has a considerable influence on value of CAC. It was also found, that increasing ionic strength affects the formation of a hydrogel. Finally, it was found that the process of preparing hydrogels does not affect formation of hydrogel.
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The use of microcalorimetric methods in the study of the protective effects of chemical chaperons
Bohunská, Miroslava ; Pekař, Miloslav (referee) ; Krouská, Jitka (advisor)
This bachelor thesis deals with the study of protective substances against denaturation processes, called chemical chaperones. The theoretical part describes the general characteristics of proteins, description of selected chaperones and methods of differential scanning calorimetry. In the experimental part, the protective effects of four potential protective agents - trehalose, guanidine hydrochloride, 3-hydroxybutyrate and hydroxyectoine - were investigated on the lysozyme model protein. The protective effects of the individual substances were examined by differential scanning calorimetry (DSC), which determined the denaturation temperature of lysozyme in the presence of preservatives. Of all the chemical chaperones examined, the highest protective effect was observed with 3-hydroxybutyrate, which shifted the denaturation temperature to higher levels, and guanidine hydrochloride, which on the other hand lowered the denaturation temperature. At the same time, a reversible denaturation process was found in some substances, which was the most intense in GuHCl.
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Characterization of carrageenan by densitometry
Poledňáková, Halina ; Krouská, Jitka (referee) ; Hurčíková, Andrea (advisor)
The density of the carrageenan solution was investigated by densitometry depending on temperature and concentration. Subsequently, ultrasonic velocity was examined using densitometry and high-resolution ultrasonic spectroscopy. The measurements were executed using aqueous and sodium chloride solutions of carrageenan in a broad range of concentrations. It was found that the carrageenan samples are not liable to irreversible changes of density and ultrasonic velocity in dependence on temperature and concentration . Furthermore, it was proved that carrageenan in both mediums is stable, the samples do not exhibit degradation or changes in the properties of the ionic strength effect.
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Influence of concentration of surfactant component and temperature on interactions between hyaluronan and katanionic vesicular systems
Janáková, Kristýna ; Jugl, Adam (referee) ; Krouská, Jitka (advisor)
The influence of various concentrations of surfactant component and various temperatures on interactions of hyaluronan with catanionic vesicular systems were examined using isothermal titration calorimetry. The measurements were performed at two different concentrations of surfactant component and three temperature values. The reason for studying the interactions was to explore the possibility of these systems serving as carriers of drugs in the future. Catanionic vesicular systems consisted of a cationic surfactant CTAB, an anionic surfactant SDS and of a positively charged two-chain surfactant DODAC. The solution of negatively charged hyaluronan with concentration of 0,5 mM was used for all measurements.
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Adsorption of microbial cells on model biological surfaces
Mikušová, Janka ; Krouská, Jitka (referee) ; Sedláček, Petr (advisor)
The aim of this bachelor thesis is creating sorption surface suitable for studying adsorption bacterial strain Lactobacillus rhamnosus, as representative probiotic bacterial strain. Included in the experimental part of this thesis was the process of creating sorption surface, according to the designed and especially optimized method. Optimization method comprised of preparing sorbent with sorption surface including mucin, on which was the bacterial strain Lactobacillus rhamnosus bound to, using specific interaction. UV-VIS spectrophotometry was utilized in the optimization of the sorption surface preparation for monitoring losses of mucin in solution that happens during the bondation on used substrate. Designed sorption surfaces were subjected to various physical-chemical analyses, which roles were displaying and characterisation of surface and confirming the presence of mucin. One of the major components, in the process of observing and characterization of changes in surface structure of the sorption surface, was infrared spectroscopy with Fourier transformation. Scanning electron microscopy was used for more detailed observation of the surface structure, created by adhesive interactions, which participate in probiotic bacteria adhesion. Finally, the created surfaces were used in pilot experiment, during which, the kinetics in growing bacterial culture with and without the presence of sorbent using microcalorimetry were observed. Designed sorbent appears to be a suitable mediator for detailed characterisation of bacterial adhesion, which is the first step in creating bacterial biofilm.
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Thermal properties of high performance fibre reinforced concrete
Pecháčková, Kateřina ; Krouská, Jitka (referee) ; Zmeškal, Oldřich (advisor)
This diploma thesis is focused on the study of the thermal properties of high-performance fiber reinforced concrete HPFRC. The composites are based on a combination of steel and polymeric fibers. Typical properties of these materials include high mechanical strength, water resistence and salt penetration. HPFRCs are mainly used in the construction industry to build tall buildings. The differential transient method was used to study thermophysical variables. The theoretical part of the thesis described the types of concrete, their production, and their properties. Furthermore, thermophysical quantities and methods of their determination (stationary and transient methods, thermal analysis) are defined in the thesis. The aim of the thesis was to determine thermal properties, namely thermal conductivity and specific heat capacity. The results of the thesis can reveal changes in the composition of studied materials as well as critical temperatures for damaging the materials.
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Stability evaluation of cosmetic dispersions using centrifugal analyser
Procházková, Michaela ; Krouská, Jitka (referee) ; Pekař, Miloslav (advisor)
This bachelor thesis is focused on the evaluation of stability of cosmetics emulsions prepared from ingredients commonly available in laboratory and compared to the stability of commercially available body lotions. In the theoretical part cosmetics emulsion and methods used to stability measurements were described. Experimental part of this work at first describes the preparation of the emulsions. Furthermore, the stability of prepared emulsion was compared to commercially available ones using the centrifugal analyser LUMiSizer. In conclusion, the test results obtained from analyser LUMiSizer have showed the stability of the commercial emulsions and two prepared samples.
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