National Repository of Grey Literature 9 records found  Search took 0.01 seconds. 
Sulfates as phase II metabolites of natural phenolic compounds
Hetman, Anastasiia ; Mladěnka, Přemysl (advisor) ; Siatka, Tomáš (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Anastasiia Hetman Supervisor: Assoc. Prof. Přemysl Mladěnka, PharmD., Ph.D. Co-supervisor: Assoc. Prof. Kateřina Valentová, Ph.D. Title of diploma thesis: Sulfates as phase II metabolites of natural phenolic compounds Natural monophenolic compounds, which both occur in plants and are formed during gut microbiota metabolism of polyphenols, are absorbed and pass through phase II metabolism. This results in the formation of various conjugated metabolites, such as sulfates, whose biological activity was not studied as yet. This work focused on the preparation and isolation of pure sulfated metabolites of phenolic compounds, namely 4- methylcatechol, protocatechuic, homoprotocatechuic, and 2,3,4-trihydroxybenzoic acid, and phloroglucinol, using the aryl sulphotransferase from Desulfitobacterium hafniense. As a result, two sulfated products of sufficient purity were prepared, namely 4- methylcatechol-O-sulfate (an inseparable mixture of 4-methylcatechol-2-O-sulfate and 4- methylcatechol-1-O-sulfate) and phloroglucinol-O-sulfate. Their antioxidantactivity was evaluated and compared with the activity of the parent compounds using the following six in vitro tests: DPPH (1-diphenyl-2-picrylhydrazyl) and...
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.
Lead-acid battery formation
Hlaváč, Pavel ; Tošer, Pavel (referee) ; Vaculík, Sebastian (advisor)
This bachelor project deals with the pulse charging of lead-acid batteries and ways of formation of electrodes so that the new batteries can constantly offer high performance and efficiency for its life. The work is an attempt to compare and determine whether the formation of different charging modes will not have a major impact on the quality of a formed battery. The formation of the different modes uses both the pulse and continuous charging. Everything is tested on four manufactured articles. The production of positive electrode and formation of accumulator is processed in various chapters of my project at our workplace.
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.
Sulphated metabolites of silybin and their interactions with sulphatases
Ježková, Zuzana ; Weignerová, Lenka (advisor) ; Kavan, Daniel (referee)
This bachelor thesis solves the question of sulphated metabolites of silybin by their interactions with sulfatases. Silybin is flavonolignan prepared from the seeds of milk thistle (Silybum marianum). Sulfate of silybin (metabolite) has not been isolated from organism so far thus its exact structure has not been determined. In this work synthesis of silybin-7,23-disulfate from natural silybin is presented. Silybin disulfate was isolated and spectrally characterized (NMR, MS). In the next step the kinetics of the reaction pNPS with sulfatase from Helix pomatia was measured: Km = 0.0494 mmol/l a Vmax = 0.0325 mmol/dm3 /min. Conditions for sulfatase reaction from Helix pomatia were selected according to literature. One of the main goal was to determine, whether silybin-7,23-disulfate is a substrate and/or an inhibitor of sulfatase from Helix pomatia. Activity measurements of the sulfatase from Helix pomatia in the presence of various concentrations of silybin-7,23-disulfate enabled us to determine that silybin disulfate at concentration higher than 0.2 mM is a strong inhibitor of the sulfatase tested. Series of reactions with sulfatase from Helix pomatia were performed to determine whether silybin-7,23-disulfate is a substrate. Reactions were monitored by HPLC and it was demonstrated that the...
Lead-acid battery formation
Hlaváč, Pavel ; Tošer, Pavel (referee) ; Vaculík, Sebastian (advisor)
This bachelor project deals with the pulse charging of lead-acid batteries and ways of formation of electrodes so that the new batteries can constantly offer high performance and efficiency for its life. The work is an attempt to compare and determine whether the formation of different charging modes will not have a major impact on the quality of a formed battery. The formation of the different modes uses both the pulse and continuous charging. Everything is tested on four manufactured articles. The production of positive electrode and formation of accumulator is processed in various chapters of my project at our workplace.
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.
Effect of titanium dioxide on the properties of lead-acid batteries operating in hybrid vehicles mode
Konečný, Zdeněk ; Tošer, Pavel (referee) ; Bača, Petr (advisor)
This work deals with lead-acid batteries operating in hybrid electric vehicles mode, i.e. in a partial state of charge. The adverse effects such as premature capacity loss and large internal resistance can markedly affect the life of a lead battery. The experiment described in this work aims to clarify the influence of the titanium dioxide in the active mass of negative electrodes especially in the life of lead acid batteries.
The methodology for the use of physical - chemical analyzes in evaluating the quality of construction materials
Haramija, Josef ; Bydžovský, Jiří (referee) ; Dufka, Amos (advisor)
This work deals mainly with physico-chemical analyses and their use in assessing the different types of degradation of building materials. In the thesis there are mentioned some of the physico-chemical analyses and on specific cases are shown their outputs and application. The practical part of the thesis describes the analysis of reinforced concrete structures, which were exposed to extremely high temperatures.

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