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Verification of the effect of fine fibers and absorbent additives on the process of self-healing concrete
Dokoupil, Tomáš ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
The diploma thesis deals with self-healing of concrete composite. In the theoretical part, it represents the effect of polymer microfibers on reducing the development of cracks and on improving self-healing properties. It also describes the most commonly used types of bacteria used to enhance the self-healing process and their effect both alone and in interaction with fibers, calcium sources and absorbent additives. It also represents auxiliary additives in the form of superabsorbent polymers. In the practical part, it verifies the influence of the above elements and describes how much the self-healing of concrete has been enhanced by the use of combinations of fibers, absorbent polymers and a source of calcium in the form of calcium lactate. It also indicates whether the self-healing properties used were not improved at the expense of deteriorating the mechanical properties of the composite.
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The influence of morphological and microstructural characteristics to land snail degradation in forest environment
Říhová, Dagmar ; Juřičková, Lucie (advisor) ; Bogusch, Petr (referee) ; Čejka, Tomáš (referee)
The decomposition of land snail shell is a complex process involving a number of factors and influences, including the characteristics of conchs themselves. In particular, it is the shell size with which the progress and the rate of degradation are tightly bound. Post-mortem changes begin with the loss of the original colour and, in the case of transparent species, by the opacification of the shell wall. Subsequently, the periostracum disruption and dissolution of calcium layers occur. However, this sequence may be reversed for some small species (e.g. Columella aspera, Nesovitrea hammonis). Animals mechanically destroy empty shells, humic acids from the substrate cause their artificial dyeing. Fungal mycelium or colonies of Streptomyces grow on the surface of the conchs. The plant roots are also involved in shell decomposition. While degradation of large shells starts with periostracum disruption and subsequent ostracal dissolution, periostracum of small shells persists even after dissolution of ostracal layers. The phenomenon is caused by high resistance of the periostraca of small species. In the case of large shells, periostracum has primarily a "building" function during shell formation, and sometimes it is flaking off already during the snail's life. For small species, it is an important part...
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Verification of the effect of fine fibers and absorbent additives on the process of self-healing concrete
Dokoupil, Tomáš ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
The diploma thesis deals with self-healing of concrete composite. In the theoretical part, it represents the effect of polymer microfibers on reducing the development of cracks and on improving self-healing properties. It also describes the most commonly used types of bacteria used to enhance the self-healing process and their effect both alone and in interaction with fibers, calcium sources and absorbent additives. It also represents auxiliary additives in the form of superabsorbent polymers. In the practical part, it verifies the influence of the above elements and describes how much the self-healing of concrete has been enhanced by the use of combinations of fibers, absorbent polymers and a source of calcium in the form of calcium lactate. It also indicates whether the self-healing properties used were not improved at the expense of deteriorating the mechanical properties of the composite.
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The influence of morphological and microstructural characteristics to land snail degradation in forest environment
Říhová, Dagmar ; Juřičková, Lucie (advisor) ; Bogusch, Petr (referee) ; Čejka, Tomáš (referee)
The decomposition of land snail shell is a complex process involving a number of factors and influences, including the characteristics of conchs themselves. In particular, it is the shell size with which the progress and the rate of degradation are tightly bound. Post-mortem changes begin with the loss of the original colour and, in the case of transparent species, by the opacification of the shell wall. Subsequently, the periostracum disruption and dissolution of calcium layers occur. However, this sequence may be reversed for some small species (e.g. Columella aspera, Nesovitrea hammonis). Animals mechanically destroy empty shells, humic acids from the substrate cause their artificial dyeing. Fungal mycelium or colonies of Streptomyces grow on the surface of the conchs. The plant roots are also involved in shell decomposition. While degradation of large shells starts with periostracum disruption and subsequent ostracal dissolution, periostracum of small shells persists even after dissolution of ostracal layers. The phenomenon is caused by high resistance of the periostraca of small species. In the case of large shells, periostracum has primarily a "building" function during shell formation, and sometimes it is flaking off already during the snail's life. For small species, it is an important part...
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Phylogenetic and ecological impact to the microstructures of mollusc shells
Nedvědová, Jana ; Juřičková, Lucie (advisor) ; Simon, Ondřej (referee)
This bachelor thesis summarizes the available information on microstructures of mollusc shells. The aim was to provide an overview of the different types of microstructures for specific specimens from different environments, as well as to obtain as much information as possible about the ecology of these animals. The first part summarizes the basic information on the shell formation. The following chapter summarizes known microstructure types of mollusc shells. Microstructures of molluscs living in terrestric, freshwater and marine environment are discussed. The influence of temperature changes on the shell microstructure of V. viviparus, the occurrence of vaterit within C. fluminea shells, the extreme environment of hydrothermal vents and cold seeps, as well as extreme temperatures on rocky shores, have been mentioned in more detail. The microstructures of related molluscs are compared with regard to ecology to determine whether the occurrence of microstructures in a particular group is given by the phylogeny of these animals, or if the changes in microstructures can be affected by different ecology. Key words: microstructures, molluscs shells, impact of phylogeny, impact of ecology, calcium carbonate, Mollusca, gastropods, bivalves
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