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Structural and transport properties of hybrid hydrogels with application utilization
Zhurauliova, Darya ; Pekař, Miloslav (referee) ; Smilek, Jiří (advisor)
The presented diploma thesis deals with the preparation and subsequent characterization of structural and transport properties of hybrid hydrogels based on polyvinyl alcohol and sodium alginate concerning their application potential. The thesis aims to study the current state of the solved issue on the topic of characterization of structural and transport (release) properties of hybrid hydrogels about their use in various branches of human activity and also based on literature research to propose and optimize a suitable preparation procedure and to carry out a series of experiments for their characterization. With regard to the literature research, suitable polymers capable of gelation, such as polyvinyl alcohol (PVA) and natural polysaccharide – sodium alginate, were selected for the preparation of hydrogels. The preparation of this hybrid network involved the physical cross-linking of PVA by freezing and thawing and ionic cross-linking of sodium alginate with calcium ions. By combining these polymers, viscoelastic, swelling and transport properties were determined by using physicochemical methods. Rheological measurements were performed to study the mechanical properties - specifically oscillation and amplitude tests. The structural properties of hydrogels (or xerogels) were determined, by scanning electron microscopy. The transport (release) properties of gel systems were determined by diffusion experiments with the UV-VIS spectrometry detection method, in which an organic dye (methylene blue) was used as a model probe. Another aim of this diploma thesis is to modify the internal structure of hybrid hydrogels with suitable reagents, ie., lecithin. The presence of lecithin in the hybrid hydrogel three-dimensional network serves as a model of the phospholipid bilayer, forming the cell membrane or occurring in tissues, and thus has a significant effect on rheological and transport properties. Physicochemical methods also determined the mechanical, swelling and transport properties of hybrid hydrogels with the addition of lecithin. The conclusion of this work is a summary of measured data to provide a comprehensive overview of this issue. The results suggest that the presence of sodium alginate in the PVA structure reduces the mechanical properties, although the presence of lecithin increases the strength of the hybrid hydrogels. However, by comparing all measurement results, it is possible to determine that sodium alginate, resp. lecithin affects the properties and structure of the hydrogel, which makes it possible to correct the properties of hybrid gel systems according to the required applications.
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Machining of polymericMaterials
Ondráček, Ivo ; Němec, Karel (referee) ; Molliková, Eva (advisor)
This bachelor’s thesis deals with the machining of polymeric materials and the major differences between the machining of metals and polymers or plastics. Introduction describes the basic elements in the history of the discovery and use of plastics. The thesis focuses on the basic division, further definitions and internal structure of the polymers. There are also discussed the most widely used machining technology and requirements for tools and materials. At the end of the work we are specified properties and selected types of plastic materials intended for processing. Practical informations were obtained during the visit to Brno company Belt Plast, Ltd.
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Structural and transport properties of hybrid hydrogels with application utilization
Zhurauliova, Darya ; Pekař, Miloslav (referee) ; Smilek, Jiří (advisor)
The presented diploma thesis deals with the preparation and subsequent characterization of structural and transport properties of hybrid hydrogels based on polyvinyl alcohol and sodium alginate concerning their application potential. The thesis aims to study the current state of the solved issue on the topic of characterization of structural and transport (release) properties of hybrid hydrogels about their use in various branches of human activity and also based on literature research to propose and optimize a suitable preparation procedure and to carry out a series of experiments for their characterization. With regard to the literature research, suitable polymers capable of gelation, such as polyvinyl alcohol (PVA) and natural polysaccharide – sodium alginate, were selected for the preparation of hydrogels. The preparation of this hybrid network involved the physical cross-linking of PVA by freezing and thawing and ionic cross-linking of sodium alginate with calcium ions. By combining these polymers, viscoelastic, swelling and transport properties were determined by using physicochemical methods. Rheological measurements were performed to study the mechanical properties - specifically oscillation and amplitude tests. The structural properties of hydrogels (or xerogels) were determined, by scanning electron microscopy. The transport (release) properties of gel systems were determined by diffusion experiments with the UV-VIS spectrometry detection method, in which an organic dye (methylene blue) was used as a model probe. Another aim of this diploma thesis is to modify the internal structure of hybrid hydrogels with suitable reagents, ie., lecithin. The presence of lecithin in the hybrid hydrogel three-dimensional network serves as a model of the phospholipid bilayer, forming the cell membrane or occurring in tissues, and thus has a significant effect on rheological and transport properties. Physicochemical methods also determined the mechanical, swelling and transport properties of hybrid hydrogels with the addition of lecithin. The conclusion of this work is a summary of measured data to provide a comprehensive overview of this issue. The results suggest that the presence of sodium alginate in the PVA structure reduces the mechanical properties, although the presence of lecithin increases the strength of the hybrid hydrogels. However, by comparing all measurement results, it is possible to determine that sodium alginate, resp. lecithin affects the properties and structure of the hydrogel, which makes it possible to correct the properties of hybrid gel systems according to the required applications.
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Criminological aspects of organized crime
Kovářová, Alena ; Scheinost, Miroslav (advisor) ; Hořák, Jaromír (referee)
7 Criminological aspects of organized crime Abstract The aim of this study named Criminological aspects of organized crime is mainly to provide a general insight to organized criminality as itself a systematize particular legal and social means, that are used to fight organized crime these days. Apart from the identification of the problems connected with application of certain means in practice I tried to outline possible solutions for the future that would lead to increasing the effectivity of fight with organized crime. The first chapter is focused on the general definition of organized crime and particular trait names that characterise organized crime and distinguish it from other forms of criminal activity. The second chapter called development of organized crime is dedicated mainly to historical roots of organized crime, its origin and changes through time. The most important global organized criminal groups are described in the second part of this chapter, which are an Italian Mafia, American La Cosa Nostra, Chinese triad and other. The third chapter focuses on typology of organized crime and particular internal organizational structure, their typical signs an expressions, whereas offers several means of division. In the fourth chapter, I devoted myself to the development of organized crime in the...
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Machining of polymericMaterials
Ondráček, Ivo ; Němec, Karel (referee) ; Molliková, Eva (advisor)
This bachelor’s thesis deals with the machining of polymeric materials and the major differences between the machining of metals and polymers or plastics. Introduction describes the basic elements in the history of the discovery and use of plastics. The thesis focuses on the basic division, further definitions and internal structure of the polymers. There are also discussed the most widely used machining technology and requirements for tools and materials. At the end of the work we are specified properties and selected types of plastic materials intended for processing. Practical informations were obtained during the visit to Brno company Belt Plast, Ltd.
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System analysis of agriculture enterprise on bioenergy production in foothills
HAMBERGEROVÁ, Jana
Chosen agricultural enterprise Agricultural-Trading Cooperative Farm operates 20 km away from České Budějovice in South Bohemia Region. Analysis of inner structure of this farm was performed for period 1997 {--} 2006. To project inner structure of the agricultural system, it is necessary to know the harvest area and yield of individual crops, cattle stock, and mineral fertilizer consumption. On the basis of performed analysis, using carbon-balance method, projects of inner structure specialized in bioenergy production were calculated. The production of bioethanol from cereals, oil from rape and biogas from cattle breeding refuse are taken into account. At comparison of individual variants from aspect of energetic gain under existing natural conditions, the variant specialized in cereals for ethanol production proves as the most suitable.
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