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Transport properties of dextran-based hydrogel systems
Vyroubal, David ; Kalina, Michal (referee) ; Klučáková, Martina (advisor)
This bachelor thesis is focused on study of transport properties of dextran-based hydrogel systems. The aim of this work is to determine their ability to absorb and release substances. Nile red was used as a probe to examine the transport properties of these systems. All hydrogels were prepared by the so-called wet way. At first stock solutions of dextran and surfactants were prepared and subsequently mixed to form a hydrogel. Nile red was dissolved in the surfactant stock solution and colored gels were formed upon mixing with dextran stock solution. Several types of gels were thus formed which differ in the concentration of the surfactant and nile red used. Supernatants were spectrophotometrically measured at various time intervals. For study of transport properties in multiple surroundings, the original supernatant was replaced after hydrogel preparation with a surfactant solution or physiological saline solution.
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Excited-state proton transfer as a tool for characterization of coloid particles
Richterová, Veronika ; Pilgrová, Tereza (referee) ; Mondek, Jakub (advisor)
This bachelor thesis deals with the study of excited-state proton transfer in micellar systems. At first critical micelle concentration of surfactants CTAB, SDS and Triton X-100 was determined. Further the steady-state and time-resolved fluorescence of probes that undergo excited-state proton transfer with these surfactants was measured. As probes were chosen 1-naphthol, HPTS and 3HNA. Deprotonation rates of 1-napthol and HPTS and average lifetime of 3HNA were calculated from time-resolved measurement. Steady-state fluorescence was used for observation surfactants influence on excited-state proton transfer.
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Evolutionary and genetic engineering of bacterial producers of polyhydroxyalkanoates
Nováčková, Ivana ; Patáková, Petra (referee) ; Koutný, Marek (referee) ; Obruča, Stanislav (advisor)
This doctoral thesis deals with the topic of evolutionary and genetic engineering of polyhydroxyalkanoates (PHA) producing bacteria. Apart from these topics, the issue of biotechnological production of PHA on model hydrolysates of lignocellulosic biomass with the use of extremophilic microorganisms is also studied, as well as the development of an alternative method of PHA isolation. The themes were freely linked to previous experiments and reflected the currently solved projects in a working group. Doctoral thesis is prepared in the form of a commented discussion of published works, which are part of it in the form of appendices. Evolutionary engineering was mainly applied to the model PHA producing bacterial strain Cupriavidus necator H16. By adaptation to levulinic acid, isolates producing copolymer P(3HB-co-3HV) with a higher content of the 3HV fraction were obtained, which leads to improved properties of the polymer for further processing. As well as culture growth also the amount of total PHA in the biomass was higher. By long-term adaptation of the same strain to osmotic stress and the presence of copper ions, the isolates which are characterized in the second publication, were obtained. Based on obtained data, it was possible to observe differences in the adaptation process, where the adaptation to osmotic stress was gradual, while a significant step in the increase of biomass and PHA signaling faster adaptation was observed for copper. Based on the analyses, the significant role of PHA in the adaptation of the C. necator H16 strain to the tested stressors was discussed, it did not consist only in the increase in the amount of polymer in the biomass, but also in enhancement of whole PHA cycle, which also leads to an increase of the pool of monomeric units showing protective functions. By adaptation to -captolactone, a unique precursor of 4HB, the copolymer P(3HB-co-4HB) was obtained. The properties of this copolymer are again more favorable than of the homopolymer P(3HB), even with a low content of 4HB, which we also achieved in a laboratory bioreactor. A further increase in the 4HB fraction could be achieved using deletion mutants with the absence of relevant genes, which is discussed more in the text. The production of PHA on models of lignocellulosic biomass hydrolysates originating from, for example, the food industry was tested in combination with the use of extremophile producers, when the preference of the contained monosaccharides (hexoses, pentoses) for individual producers was discussed. For the purpose to get closer to real hydrolysates, the resistance of the strains to relevant potential microbial inhibitors was also tested. The susceptibility of halophilic and thermophilic PHA producers to osmotic stress was used in the development of an alternative isolation approach that would reduce the economic and ecological burden of the process compared to standard extraction using chlorinated solvents. Application of SDS detergent at low concentrations while simultaneously exposing the cells to higher temperatures led to the gain of high purity polymer without loss of yield. The recycling process of used SDS is also a possibility.
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Influence of surfactants in electroless nickel bath on properties of Ni-P coatings on AZ91 magnesium alloy
Buday, Patrik ; Wasserbauer, Jaromír (referee) ; Buchtík, Martin (advisor)
This bachelor thesis deals with the effect of surfactants on mechanical properties and structure of Ni-P coatings on AZ91 magnesium alloy. The theoretical part of the thesis includes summary of basic knowledge about magnesium alloys, surfactants and electroless deposition of Ni-P coatings, including a detailed description of Ni-P reduction on substrate. The theoretical part is concluded by current research in the field of Ni-P coatings. In the experimental part, morphology of Ni-P coatings was observed by electron microscopy (SEM). Using a light microscope (LM), the effect of surfactants on the deposition rate was observed. By means of energy dispersion analysis, the average phosphorus content of Ni-P coatings was determined. The hardness as a mechanical property of these coatings was determined using a micro hardener.
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Diffusion of dyes in biopolymeric hydrogels
Vyroubal, David ; Mravec, Filip (referee) ; Klučáková, Martina (advisor)
This thesis is focused on diffusion of dyes in biopolymer-based hydrogels. These hydrogels are based on interaction between biopolymer-like electrolytes with oppositely charged surfactants. When polyelectrolytes interact with oppositely charged surfactants, micelle-like nano-containers can be formed. These nano-containers are able of binding hydrophobic compounds. In this study, combination of modified dextran (diethylaminoethyl dextran) with positive charge and oppositely charged sodium dodecylsulphate as surfactant was used for preparation of hydrogels. Next type of hydrogel was based on hyaluronan and positive charged surfactant Septonex (carbethoxypendecinium bromide). As a diffusion probes in hydrogels dyes Nile red and ATTO 488 were used. The diffusion of these dyes from aqeous solutions of NaCl or surfactants into hydrogels was monitored in time. Transport of dyes into structure of hydrogels was characterized by diffusion coefficients and structural parameters of hydrogels.
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Fluorescence probes to study the properties of hydrogel systems
Máčala, Jakub ; Venerová, Tereza (referee) ; Mravec, Filip (advisor)
This bachelors thesis is focused on possibility of selected fluorescent probes for study of properties of hydrogel systems. Chosen probes are Prodan for polarity study, HPTS for measurement of pH of the probe environment and platinum complex [2,6-Bis(2-pyridyl)fenyl-C,N,N]chloroplatinum(II) for its unique fluorescence properties and potential of energy transfer studies in hydrogel systems. Spectral properties of fluorophores were defined in selected set of solvents with different polarity with steady state fluorescence spectroscopy method. Properties of HPTS probe were also tested in buffers with different pH. Subsequently, hydrogels based on hyaluronan-septonex and dextran-SDS with incorporated fluorescence probes were prepared. Steady state fluorescence measurement of fluorophores from hydrogel were made using fluorimeter optical fibres. It was found, that probes Prodan and HPTS are suitable for study of polarity and pH of hydrogels and probably they will be able to be used for study of hydrogel with other techniques, like fluorescence microscopy, however platinum complex is, due to the low fluorescence intensity and possible quenching by polar water environment, probably not suitable for other measurements.
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Transport properties of dextran-based hydrogel systems
Vyroubal, David ; Kalina, Michal (referee) ; Klučáková, Martina (advisor)
This bachelor thesis is focused on study of transport properties of dextran-based hydrogel systems. The aim of this work is to determine their ability to absorb and release substances. Nile red was used as a probe to examine the transport properties of these systems. All hydrogels were prepared by the so-called wet way. At first stock solutions of dextran and surfactants were prepared and subsequently mixed to form a hydrogel. Nile red was dissolved in the surfactant stock solution and colored gels were formed upon mixing with dextran stock solution. Several types of gels were thus formed which differ in the concentration of the surfactant and nile red used. Supernatants were spectrophotometrically measured at various time intervals. For study of transport properties in multiple surroundings, the original supernatant was replaced after hydrogel preparation with a surfactant solution or physiological saline solution.
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The role of SDS in the events of the 1960s in Germany
Skotnicová, Anita ; Šmidrkal, Václav (advisor) ; Kučera, Rudolf (referee)
The 1960s were marked by a large number of demonstrations in the Western world, mostly attended by students. The increased civic activity of the young generation first appeared in the US when students protested against the war in Vietnam. In the Federal Republic of Germany, the events in Vietnam also belonged to important topics, but at the same time long-term problems of the society escalated too. There have been changes at both political and cultural levels. In the second half of the 1960s, a series of stormy demonstrations took place in Germany over this constellation. This thesis focuses on the "Socialist German Student Union" (SDS), which became the imaginary engine of the student protest movement of the 1960s. At the beginning, the work presents a global context, then the main topics and milestones of the development in Germany in the political, social and cultural spheres. Secondly, the development of the SDS is outlined, with an emphasis on the main themes of the association. Then, the course of the demonstrations in the 1960s, SDS activity and the subsequent development after 1969 is analyzed. Finally the work offers an evaluation of SDS success in advancing its long-term goals in the 1960s.
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The failure of the New Left in the US: the case of SDS
Vítek, Tomáš ; Kralj, Dejan (advisor) ; Calda, Miloš (referee)
This thesis The Failure of the New Left in the US: The Case of SDS analyzes the causes and reasons of the failure of the New Left in the United States. The left-leaning students who were discontent with the social order and reality of the country gathered under the idea of participatory democracy in a group called Students for a Democratic Society. Their aim was to change and improve the system through universities being agents of social change, thus making a clear difference with the Old Left. The worker no longer stood in the center of social progress, but the student did. SDS promptly plunged into several burning issues of the era, such as civil rights movement and inferior position of the blacks and poor in the society. The Vietnam War and antiwar protest movement have also been great issues in which SDSers directed their energy. As the Vietnam War escalated in terms of American soldiers being sent overseas, the intensity of student protests grew as well. Inevitably SDS resorted to usage of violent means of expressing dissent and clashed with the forces of the establishment. The thesis seeks to answer what reasons, events and realities led them to finally adopting revolutionary Marxism as their flag ideology. Soon after that SDS broke up and its once great influence waned away.
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Utilization of light scattering techniques in study on protein denaturation
Köbölová, Klaudia ; Kalina, Michal (referee) ; Sedláček, Petr (advisor)
This bachelor thesis is focused on verifying the use of light scattering techniques in the study of protein denaturation. The theoretical part of the thesis describes proteins, their general properties, the process of denaturation and it provides an insight into light scattering. In the experimental part of the study I investigated the denaturation effects of four selected potential denaturing agents – urea, guanidine hydrochloride, sodium dodecyl sulfate, copper (II) sulfate – on two model enzymes: lipase and lysosyme. The denaturation effects of these denaturants were studied with the help of the dynamic light scattering method (DLS). In order to describe the change in particle size during denaturation, I used Z-Average, Volume mean and intensity distribution which were determined by this method.
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