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Using of X-ray for distribution analysis of electrodes for secondary cell application
Macháč, Milan ; Bača, Petr (referee) ; Chladil, Ladislav (advisor)
This diploma thesis is focused on in-situ analysis of the composition of the negative electrodes of second secondary cells with using X-ray radiation. The first part is dedicated to the theory of lead accumulators, including charging, discharging, battery components and individual degradation mechanisms. The main part of the thesis includes the preparation of electrochemical in situ XRD cells and following measurement of the growth of lead sulphate crystals on the OCV potential. Furthermore, the lead cell was subjected to the measurement of the cyclic voltammetry around the working point of the negative electrodes. From these measurements was evident gradual increase of the lead sulfate crystals. The analysis was supplemented with electron microscopy images. In addition, were evaluated the in-situ particle analysis of the LTO Sigma sample.
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Microscopic Observations of Active Mass Structures of the Negative Electrode of a Lead-Acid Battery
Zimáková, Jana ; Dostál, Zdeněk (referee) ; Kohout,, Jan (referee) ; Bača, Petr (advisor)
This doctoral dissertation deals with the study of the effect of additives on the properties of the negative electrode of a lead-acid battery. The work focuses on the investigation of the additive/base material interface for the negative electrode (so-called active mass) using atomic force microscopy (AFM). A lead sheet was used as the base material, on which the given additive was applied. The effects of carbon, TiO2, glass fibers and Indulin AT were specifically investigated. The negative electrode was cycled by a potentiostat in a defined manner and the morphology of the electrode surface was continuously scanned by AFM. This created a time sequence of images on which events on the surface of the electrode during its charging/discharging were captured. These records serve to better understand the effect of additives on the resulting properties of constructed lead-acid cells, specifically on the ability to form or dissolve PbSO4 crystals, which are formed during cell discharge and are responsible for the decrease in total capacity - gradual surface sulfation.
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Durability of repair materials with higher fire resistance for concrete structures
Počekajlo, Václav ; Dohnálek,, Pavel (referee) ; Bydžovský, Jiří (advisor)
This dissertation deals with the study of durability and degradation repair mortars for reinforced concrete structures. In its theoretical part, there are the research findings on the behavior of repair mortars exposed to corrosive environments with different exposure time and selected high temperatures. Processes occurring in repair mortars during their loading at high temperatures or when exposed to chemically aggressive environments are described, We can find recipes designed for cementitious binder based with a specific replacement using slag or fly ash in its practical part. The object of the research was to determine the durability of the proposed repair mortars, and determine their suitability for use on concrete structures, which may be exposed to a synergistic effect of chemically aggressive environments with high temperatures simulating fire.
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Production and characterization of novel aryl sulfotransferases and their use in bioanalytics
Petránková, Barbora ; Bojarová, Pavla (advisor) ; Křížek, Tomáš (referee)
Polyphenols are the most common natural substances found in food. The largest group is represented by flavonoids, phenolic acids and catechols. Polyphenols are metabolized in the body during the biotransformation phase II, they can be sulfated, glucuronylated or methylated. To study biotransformation, it is necessary to have defined standards. Sulfated polyphenols can be prepared by enzymatic sulfation, which needs much milder reaction conditions compared to chemical sulfation. Prokaryotic sulfotransferases use 3'-phosphoadenosine-5'-phosphosulfate (PAPS) as a sulfate donor for sulfation, which is very expensive and difficult to regenerate. An alternative is the group of bacterial aryl sulfotransferases (EC 2.8.2.22), which catalyze the transfer of a sulfate group from a phenolic donor to a phenolic acceptor. Two bacterial aryl sulfotransferases from Desulfitobacterium hafniense and Escherichia coli have been described in the literature so far. The present thesis deals with the production, purification and biochemical characterization of two new bacterial aryl-sulfotransferases from Desulfosporosinus sp. HMP52 and Salmonella bongori. The enzymes were heterologously expressed in E. coli and purified by affinity chromatography. Their pH and temperature optimum, stability in organic solvents and...
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Genetic knockout of CS4 sulfation of perineuronal nets as a source of juvenile like plasticity in processes of memory and learning
Gmiterková, Lenka ; Růžička, Jiří (advisor) ; Telenský, Petr (referee)
Extracellular matrix affects the functioning of the brain. Among others, learning and memory can be affected by the changes in the composition and properties of the extracellular matrix. Different sulfation patterns on the chondroitin sulfate proteoglycans, one of the extracellular matrix components, can either enhance or reduce synaptic plasticity and neuronal growth. This leads to the changes in the formation of memory. In my thesis I defined the role of 4-O-sulfation of the chondroitin sulfate proteoglycans in the learning and memory in the young and early adult animals. To do so I used Chondroitin sulfotransferase 11 knockout mice strain, which has decreased amount of 4-O-sulfation. I tested their long-term, short-term, and working memory using behavioural tests. I also monitored the morphological changes in the perineuronal nets and changes in the number of synapses using immunohistochemical methods and confocal microscopy.
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Analysis of sulfated flavonoids by HPLC-MS/MS
Petránková, Barbora ; Bojarová, Pavla (advisor) ; Kozlík, Petr (referee)
The aim of this work is to find the optimal separation conditions in high performance liquid chromatography for the analysis of sulfated polyphenolic substances, especially flavonoids, phenolic acids and catechols. Three chromatographic columns were used in the development of the method. ZIC-HILIC column with polar organic phase and C18 and Kinetex PFP columns with reverse phase. We focused in particular on a short time of separation, sharp tailless peaks and separation of all components of the mixture. Using a Kinetex PFP column, the optimal method for separating the test mixtures was found. The use of a mobile phase of 10 mM ammonium acetate/0,1% fromic acid and methanol was shown to be the most appropriate, with a mobile phase flow rate of 0,6 ml/min. By modifying the gradient and temperature, all components of the tested mixtures were separated, the peaks were sharp, and the separation time in most cases ranged do not exceed 10 min. The method is also directly applicable in conjunction with a mass detector. Keywords: High Performance Liquid Chromatography (HPLC), flavonoids, polyphenolic substances, sulfation, separation
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Microscopic Observations of Active Mass Structures of the Negative Electrode of a Lead-Acid Battery
Zimáková, Jana ; Dostál, Zdeněk (referee) ; Kohout,, Jan (referee) ; Bača, Petr (advisor)
This doctoral dissertation deals with the study of the effect of additives on the properties of the negative electrode of a lead-acid battery. The work focuses on the investigation of the additive/base material interface for the negative electrode (so-called active mass) using atomic force microscopy (AFM). A lead sheet was used as the base material, on which the given additive was applied. The effects of carbon, TiO2, glass fibers and Indulin AT were specifically investigated. The negative electrode was cycled by a potentiostat in a defined manner and the morphology of the electrode surface was continuously scanned by AFM. This created a time sequence of images on which events on the surface of the electrode during its charging/discharging were captured. These records serve to better understand the effect of additives on the resulting properties of constructed lead-acid cells, specifically on the ability to form or dissolve PbSO4 crystals, which are formed during cell discharge and are responsible for the decrease in total capacity - gradual surface sulfation.
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Using of X-ray for distribution analysis of electrodes for secondary cell application
Macháč, Milan ; Bača, Petr (referee) ; Chladil, Ladislav (advisor)
This diploma thesis is focused on in-situ analysis of the composition of the negative electrodes of second secondary cells with using X-ray radiation. The first part is dedicated to the theory of lead accumulators, including charging, discharging, battery components and individual degradation mechanisms. The main part of the thesis includes the preparation of electrochemical in situ XRD cells and following measurement of the growth of lead sulphate crystals on the OCV potential. Furthermore, the lead cell was subjected to the measurement of the cyclic voltammetry around the working point of the negative electrodes. From these measurements was evident gradual increase of the lead sulfate crystals. The analysis was supplemented with electron microscopy images. In addition, were evaluated the in-situ particle analysis of the LTO Sigma sample.
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Durability of repair materials with higher fire resistance for concrete structures
Počekajlo, Václav ; Dohnálek,, Pavel (referee) ; Bydžovský, Jiří (advisor)
This dissertation deals with the study of durability and degradation repair mortars for reinforced concrete structures. In its theoretical part, there are the research findings on the behavior of repair mortars exposed to corrosive environments with different exposure time and selected high temperatures. Processes occurring in repair mortars during their loading at high temperatures or when exposed to chemically aggressive environments are described, We can find recipes designed for cementitious binder based with a specific replacement using slag or fly ash in its practical part. The object of the research was to determine the durability of the proposed repair mortars, and determine their suitability for use on concrete structures, which may be exposed to a synergistic effect of chemically aggressive environments with high temperatures simulating fire.
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