National Repository of Grey Literature 17 records found  1 - 10next  jump to record: Search took 0.01 seconds. 
Preparation and characterisation of polysaccharide hydrogels
Kulíšková, Kateřina ; Kadlec, Martin (referee) ; Smilek, Jiří (advisor)
This bachelor thesis deals with the study of preparation and characterization of alginate hydrogels. It focuses mainly on the ionic crosslinking of alginate using divalent metal cations Ca2+, Cu2+, Zn2+, Ba2+, Fe2+ together with the trivalent cation Fe3+ in order to compare the crosslinking abilities of different oxidation states. The exogenous method was used for the preparation of alginate hydrogels and the prepared hydrogels were thus studied in the form of millimetre spheres. In the experimental part, optimization was performed to find out the optimum gelation time, which resulted in the crosslinking of the hydrogels throughout their volume. Ca2+ ions were used as a reference due to their wide application and the extensive experience with these ions at the faculty. The knowledge from the optimization was applied to the preparation of the other ions samples. The viscoelastic properties of the hydrogels were investigated by rheological measurements in the form of amplitude and squeeze tests. All ions, except Fe2+, were found to crosslink the hydrogels throughout the volume. Based on the complex modulus, the order of ions was determined according to the degree of crosslinking, The degree of crosslinking also has major impact on the degree of syneresis.
Time-temperature superposition principle used for study of rheological properties of polymer materials
Kadlec, Martin ; Jarábková, Sabína (referee) ; Smilek, Jiří (advisor)
This bachelor thesis provides a study of the “time-temperature superposition” principle and its applicability to hydrogels. According to current research, honey was chosen due to its simple viscoelastic properties (Newtonian liquid) as a suitable material for optimalization procedure. The knowledge obtained during optimization was further applied to real hydrogel materials, namely the agarose gel was selected as an example of thermoreversible hydrogel, as well as the hyaluronan and dextran gels as examples of hydrogels formed by the interaction of the polyelectrolyte with the opposite charged surfactant. By using the “time-temperature superposition” principle, a considerable increase in the range of the observed oscillation frequencies was achieved for all chosen samples, which led to gain of information about storage and loss or complex modulus, which could not be achieved by classical oscillatory test. Although master curves were generated for all the samples examined, curves for storage and loss modulus could be created separately only for hydrogels formed by the interaction of the polyelectrolyte with the opposite charged surfactant. For this reason, this group of hydrogels appears to be more suitable materials for the application of the “time-temperature superposition” principle.
Small hydraulic press for bio-briquet
Kadlec, Martin ; Mazůrek, Ivan (referee) ; Prokeš, František (advisor)
The aim of this master´s thesis was the design of a small hydraulic press for bio-briquettes according to predetermined parameters. The theoretical part presents the current situation in terms of biomass processing, briquette production and a description of briquetting presses. The practical part deals with solutions and detailed structural design of the selected alternatives. Models and drawings were created in the SolidWorks 2011.
Polysaccharide gels in medical applications
Svitačová, Denisa ; Kadlec, Martin (referee) ; Venerová, Tereza (advisor)
This bachelor thesis deals with the performance of hydrogels containing polysaccharides, their characterization and reproducibility of the preparation of these gels, which is described in the literature. Based on the research, suitable polysaccharides, namely guar and gellan gum, were selected. Subsequently, an article was selected, the procedure of which was reproduced. Calcium chloride was used as a crosslink agent in the mixture of guar gum and gellan solution. Problems appear in the reproducibility of the article which did not allow the exact repetition of the hydrogel preparation procedure described in the article. Based on the findings, an optimized range of mixtures with various other gelling agents was developed. The individual prepared materials were suitably characterized by rheological tests. Specifically, amplitude tests, the results of which proved the formation of a three-dimensional network in their structure, and thus the formation of hydrogels. Frequency tests were used to determine their mechanical properties.
ECU controlled car systems
Kadlec, Martin ; Klapka, Milan (referee) ; Strecker, Zbyněk (advisor)
The aim of bachelor thesis is to give an overview of the state of knowledge in the field of controlled car systems and to estimate development in the future. The first part describes the basic terms in the field of exist problems. In the next part are detailed analysis of systems with their allocation and definition.
Rheology as a powerful tool for the complex characterization of hydrogels
Kadlec, Martin ; Kráčalík, Milan (referee) ; Smilek, Jiří (advisor)
This diploma thesis investigates the suitability of relaxation tests as a part of complex characterization of hydrogel materials using classical rheology methods. With respect to the current research, creep and three interval thixotropy tests were taken into account. For them, general optimization was done aiming to find an ideal parameter settings. The optimization was performed using physically crosslinked agarose (AG) hydrogel and the tuned tests were also applied to two more samples: hyaluronan (HyA) and polyvinyl alcohol (PVAl) gel. These materials were selected due to their mutually different crosslinking principle. The experiments showed, the AG gel proved to have the best ability to recover after deformation of all studied samples. On the other hand, the HyA gel relaxed the worst. Although the final results of both tests were comparable, the regeneration process itself was different. Hence, the complex relaxation characteristics cannot be described using one of the performed tests alone and both the creep and three interval thixotropy tests have great importance in the scope of complex relaxation behaviour. The obtained results may lead to more precise description of deformation and relaxation, which are frequent phenomena occurring during treatment and application of hydrogel materials.
Polysaccharide gels in medical applications
Svitačová, Denisa ; Kadlec, Martin (referee) ; Venerová, Tereza (advisor)
This bachelor thesis deals with the performance of hydrogels containing polysaccharides, their characterization and reproducibility of the preparation of these gels, which is described in the literature. Based on the research, suitable polysaccharides, namely guar and gellan gum, were selected. Subsequently, an article was selected, the procedure of which was reproduced. Calcium chloride was used as a crosslink agent in the mixture of guar gum and gellan solution. Problems appear in the reproducibility of the article which did not allow the exact repetition of the hydrogel preparation procedure described in the article. Based on the findings, an optimized range of mixtures with various other gelling agents was developed. The individual prepared materials were suitably characterized by rheological tests. Specifically, amplitude tests, the results of which proved the formation of a three-dimensional network in their structure, and thus the formation of hydrogels. Frequency tests were used to determine their mechanical properties.
Analysis of migration from Ukraine to the Czech Republic
Kadlec, Martin ; Šír, Jan (advisor) ; Klípa, Ondřej (referee)
Ukrainians are the largest minority in the Czech Republic and they form an important part of both Czech society and its economy nowadays. The bachelor thesis analyzes the causes of Ukrainian migration to the Czech Republic. Regression analysis was performed to obtain results. The work concludes that motivation of Ukrainian migration is the economic attractiveness of the Czech Republic. However, it is not possible to ignore the cultural, ethnic, historical and linguistic relationship of these two nations. Keywords Ukraine, Ukrainian migration, internationa migration, diaspora, Czech republic, labor market
Rheology as a powerful tool for the complex characterization of hydrogels
Kadlec, Martin ; Kráčalík, Milan (referee) ; Smilek, Jiří (advisor)
This diploma thesis investigates the suitability of relaxation tests as a part of complex characterization of hydrogel materials using classical rheology methods. With respect to the current research, creep and three interval thixotropy tests were taken into account. For them, general optimization was done aiming to find an ideal parameter settings. The optimization was performed using physically crosslinked agarose (AG) hydrogel and the tuned tests were also applied to two more samples: hyaluronan (HyA) and polyvinyl alcohol (PVAl) gel. These materials were selected due to their mutually different crosslinking principle. The experiments showed, the AG gel proved to have the best ability to recover after deformation of all studied samples. On the other hand, the HyA gel relaxed the worst. Although the final results of both tests were comparable, the regeneration process itself was different. Hence, the complex relaxation characteristics cannot be described using one of the performed tests alone and both the creep and three interval thixotropy tests have great importance in the scope of complex relaxation behaviour. The obtained results may lead to more precise description of deformation and relaxation, which are frequent phenomena occurring during treatment and application of hydrogel materials.
Time-temperature superposition principle used for study of rheological properties of polymer materials
Kadlec, Martin ; Jarábková, Sabína (referee) ; Smilek, Jiří (advisor)
This bachelor thesis provides a study of the “time-temperature superposition” principle and its applicability to hydrogels. According to current research, honey was chosen due to its simple viscoelastic properties (Newtonian liquid) as a suitable material for optimalization procedure. The knowledge obtained during optimization was further applied to real hydrogel materials, namely the agarose gel was selected as an example of thermoreversible hydrogel, as well as the hyaluronan and dextran gels as examples of hydrogels formed by the interaction of the polyelectrolyte with the opposite charged surfactant. By using the “time-temperature superposition” principle, a considerable increase in the range of the observed oscillation frequencies was achieved for all chosen samples, which led to gain of information about storage and loss or complex modulus, which could not be achieved by classical oscillatory test. Although master curves were generated for all the samples examined, curves for storage and loss modulus could be created separately only for hydrogels formed by the interaction of the polyelectrolyte with the opposite charged surfactant. For this reason, this group of hydrogels appears to be more suitable materials for the application of the “time-temperature superposition” principle.

National Repository of Grey Literature : 17 records found   1 - 10next  jump to record:
See also: similar author names
30 KADLEC, Michal
22 KADLEC, Miroslav
2 Kadlec, Marek
1 Kadlec, Matěj
30 Kadlec, Michal
4 Kadlec, Milan
2 Kadlec, Miloš
22 Kadlec, Miroslav
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