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National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Reduktivní defekty vín a možnosti jejich odstranění
 Maleňáková, Daniela
This diploma thesis deals with reductive sulphur off-odors in wines and possibilities of their removal. The theoretical part describes substances causing these defects, their threshold values, most common causes of defects and possibility of their prevention or removal. The practical part is focused on the determination of hydrogen sulphide (H2S) in wine with reductive sulphur off-odor and the possibility of reducing its content using particles of gold, silver and copper. A wine with reductive off-odor made of the Zweigeltrebe variety from 2018 was used for the experiment. 10 l micro-samples were created and various doses of silver, gold and copper-based products were applied to the wine. The control samples were left untreated. The UV / VIS HPLC instrumentation was used for determination of the hydrogen sulphide concentration using so far unpublished method for converting H2S to methylene blue with direct injection of the derivatized wine sample. The H2S concentration in the samples varied from 13,1 to 68,7 µg/l. Basic analytical parameters were also measured and compared in this work, but they did not changed significantly with added products doses. The GC-MS method was used to measure the levels of particular volatile compounds. Treated wines were also sensory evaluated. The best sensory properties exhibited wines treated with copper products.
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Interactions of Hydrogen Sulfide Releasing Enzymes in Porcine Oocytes during Meiotic Maturation
Jiříček Hasalová, Simona ; Hošková, Kristýna (advisor) ; Tomáš, Tomáš (referee)
The reproductive biotechnologies currently represent a major scientific discipline based on a sufficient quantity of wholesome oocytes matured in vitro conditions to acquire permits for their effectiveness. The meiotic maturation is a complex process where a wide range of factors is involved in the regulation. One of these factors are small gaseous molecules, so-called gasotransmitters. These gases demonstrate number of physiological functions in the organism and the latest discovered gasotransmitter is hydrogen sulfide (H2S). The aim of this thesis was to test the hypothesis according to which there are enzymes present in porcine oocytes that produce H2S (CBS, CTH, 3-MPST), their distribution is in interaction and their joint actions influence the process of the meiotic maturation. The resulting data were obtained on the basis of immunocytochemical staining and colocalization analysis. The results proofed the presence of H2S-releasing enzymes in porcine oocytes. It was also confirmed the function of these enzymes in relation to the regulation of the meiotic maturation when oocytes cultured with triple inhibitors of H2S-releasing enzymes matured more slowly. The results also showed medium correlation dependence of enzymes CBS, CTH and 3-MPST. The combination of CBS and 3-MPST resulted in high correlation dependence which confirmed their interaction both in immature oocytes and in vitro matured oocytes. It is evident that so far studied effects of H2S are only a fraction of skills which this signal molecule possesses. There exists a need for future experiments to help us describe and explain the acting mechanisms of H2S.
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