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Utilization of various methods of porosimetry in investigation of internal structure of biopolymer hydrogels
Zahrádka, Jan ; Pekař, Miloslav (referee) ; Sedláček, Petr (advisor)
The main aim of the thesis was to select, optimize and test suitable methods for studying inner structure of hydrogel materials. The study of the size of pores with potential use in fundamental and applied research of these materials is the central focus of the thesis. Firstly, a literature search was done in order to collect basic information about usefulness of the individual methods. On the basis of this literature search, the experimental part of the work was divided into several steps. First, selected methods of conventional porosimetry (mercury intrusion porosimetry, BET analysis and DSC thermoporometry) were applied on reference porous materials and the results obtained by the individual methods were compared. The methods optimized with the use of these reference materials were then utilized in the analysis of porosity of model hydrogels based on polyvinyl alcohol. Based on the results of this analysis, the usability and benefits of the individual methods were discussed with respect to the sample preparation, time and financial demands, and also from the viewpoint of compliance of the determined pore sizes with the range of sizes declared for the physical PVA gels.
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Optimization of optical and transport properties of PVA based hydrogels
Zahrádka, Jan ; Kalina, Michal (referee) ; Sedláček, Petr (advisor)
The main goal of this bachelor thesis is to design and optimize a suitable method for preparation of transparent physically crosslinked hydrogels with manipulable transport properties. Polyvinyl alcohol (PVA) crosslinked by cyclic freezing and thawing was chosen as the model gel-forming material. From the originally proposed three mechanisms of influencing optical properties of thus prepared PVA gels, the influence of freezing rate was selected on the basis of pilot screening experiments for a deeper follow-up analysis. The mechanical properties of prepared hydrogels were analyzed by rheology using strain sweep test. The internal structure was visualized by scanning electron microscopy (SEM). The optimized technique for preparation of transparent PVA gels was subsequently used for preparation of gels with an interpenetrated polyelectrolyte component (poly (styrene sulfonate)). It was then experimentally verified by diffusion pair method with methylene blue as diffusion probe that the hybrid hydrogel network has modified transport properties.
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An Impact of Security Situation on the Position of Israeli Right
Zahrádka, Jan ; Kalhousová, Irena (advisor) ; Záhora, Jakub (referee)
Teze k bakalářské práci Název: Vliv bezpečnostní situace na postavení izraelské pravice Autor: Jan Zahrádka Školitel: Dr. Irena Kalhousová Klíčová slova: Izrael, bezpečnostní situace, teroristické organizace, pravice Výzkumná otázka: Jakou roli hrály významné bezpečnostní hrozby a teroristické útoky v postavení izraelské pravice od podepsání Mírové dohody v Oslu po současnost a jaký měly vliv na úspěchy pravicových stran v parlamentních volbách? Můžeme na základě těchto poznatků pozorovat opakující se vzor, jak se pravice v Izraeli chová v závislosti na těchto bezpečnostních hrozbách? Význam tématu: Izraelsko-palestinský konflikt je dobře známý, avšak velmi těžce řešitelný problém. Nespočet historiků, politologů a expertů na mezinárodní vztahy se pokoušelo, a stále pokouší, definovat příčiny vzniku a trvání tohoto konfliktu. Někteří se také snaží navrhnout jeho řešení, zatím však ale neúspěšně. V mé práci se pokusím vysvětlit, jaké stanovisko zaujímají izraelské pravicové strany vůči této problematice a jak se staví k otázce mírového řešení. Dále se pokusím zjistit, jestli je toto chování, a případně do jaké míry, ovlivněno bezpečnostní situací v Izraeli. Seznam literatury: Alexander, Y. (2021). Palestinian religious terrorism: Hamas and Islamic jihad. BRILL Bickerton, I. J., & Klausner, C. L. (2018). A...
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Utilization of various methods of porosimetry in investigation of internal structure of biopolymer hydrogels
Zahrádka, Jan ; Pekař, Miloslav (referee) ; Sedláček, Petr (advisor)
The main aim of the thesis was to select, optimize and test suitable methods for studying inner structure of hydrogel materials. The study of the size of pores with potential use in fundamental and applied research of these materials is the central focus of the thesis. Firstly, a literature search was done in order to collect basic information about usefulness of the individual methods. On the basis of this literature search, the experimental part of the work was divided into several steps. First, selected methods of conventional porosimetry (mercury intrusion porosimetry, BET analysis and DSC thermoporometry) were applied on reference porous materials and the results obtained by the individual methods were compared. The methods optimized with the use of these reference materials were then utilized in the analysis of porosity of model hydrogels based on polyvinyl alcohol. Based on the results of this analysis, the usability and benefits of the individual methods were discussed with respect to the sample preparation, time and financial demands, and also from the viewpoint of compliance of the determined pore sizes with the range of sizes declared for the physical PVA gels.
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Optimization of optical and transport properties of PVA based hydrogels
Zahrádka, Jan ; Kalina, Michal (referee) ; Sedláček, Petr (advisor)
The main goal of this bachelor thesis is to design and optimize a suitable method for preparation of transparent physically crosslinked hydrogels with manipulable transport properties. Polyvinyl alcohol (PVA) crosslinked by cyclic freezing and thawing was chosen as the model gel-forming material. From the originally proposed three mechanisms of influencing optical properties of thus prepared PVA gels, the influence of freezing rate was selected on the basis of pilot screening experiments for a deeper follow-up analysis. The mechanical properties of prepared hydrogels were analyzed by rheology using strain sweep test. The internal structure was visualized by scanning electron microscopy (SEM). The optimized technique for preparation of transparent PVA gels was subsequently used for preparation of gels with an interpenetrated polyelectrolyte component (poly (styrene sulfonate)). It was then experimentally verified by diffusion pair method with methylene blue as diffusion probe that the hybrid hydrogel network has modified transport properties.
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Elektronický podpis jako služba České pošty
Havlan, Jan ; Toman, Prokop (advisor) ; Zahrádka, Jan (referee)
Bakalářská práce se zabývá problematikou elektronického podpisu jako služby, kterou poskytuje Česká pošta. Nejprve popisuje, co elektronický podpis vlastně je, jeho hlavní principy fungování, související technické náležitosti a legislativu elektronického podpisu. Poté se zabývá nabídkou certifikačních služeb České pošty a samotnými postupy získání certifikátů dle jednotlivých kritérií. Práce může sloužit jako stručný teoretický popis postupu k získání elektronického podpisu u České pošty.
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