National Repository of Grey Literature 111 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Recovery of the method for assessment of fatty acids
Gross, Michal ; Hrstka, Miroslav (referee) ; Vítová, Eva (advisor)
The objective of this bachelor thesis is to verify recovery yield used for determination of fatty acids based on gas chromatography with flame-ionization detection. In the theoretical part, fatty acids and lipids are characterized and extraction of lipidic fraction from food samples with its subsequent adjustments is suggested. Furthermore, the principle and current instrumentation of capillary gas chromatography with flame-ionization detection and standard parameters for validation of the analytical method are specified. In the experimental part, verification of recovery yield of the method for assessment of fatty acids was performed. The used method includes extraction of lipids from a sample in accordance with the standard ISO 1735 regulation and transesterification of both free and bounded fatty acids catalysed by boron trifluoride according to the ISO 12966-2 standard regulation. The produced methyl esters can be effectively determined using gas chromatography with flame-ionization detector. Analysed samples of rapeseed oil and tilsiter-type cheese were purchased in a common food market.
Accuracy of the method for assessment of allergenic aroma compounds
Rychetský, Matěj ; Hrstka, Miroslav (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the verification of the accurancy of the method for determination of potentially allergenic substances in confectionery. In the theoretical part the synthetic and natural fragrances, which are present in foodstuffs are described. Furthermore, the method of solid phase microextraction in connection with gas chromatography with mass spectrometry, which was used in the measurement, is briefly characterized. Finally, the basic criteria measured in the validation of the analytical method are described. In the experimental part, the repeatability and reproducibility of the HS-SPME-GC-MS method for the determination of potentially allergenic substances in candy samples was verified. It was found by the measurement that the used method is suitable for qualitative determination (based on retention times), but the method shows minor inaccurancies in quantitative determination (determination based on peaks area) and it will be improved in following experiments.
The effect of temperature and drought on the glutenin proteins content in two genotypes of wheat
Vybíral, Lukáš ; Vespalcová, Milena (referee) ; Hrstka, Miroslav (advisor)
This bachelor thesis deals with the influence of water and temperature deficiency on protein content of gliadin fraction and on glutenin/gliadin ratio in two wheat varieties. The varieties selected for the experiment are called Pannonia and RGT Reform. Samples were cultivated at three different temperatures, 26 °C, 32 °C and 38 ° C, and irrigation was checked at the time of flowering. For wet-grown samples, the soil had a moisture content greater than 70 %, and drought-grown specimens grew on soil with a moisture content not exceeding 30 %. After harvest, the grains were ground into flour and glutenins and gliadins were extracted from the individual samples. SDS-PAGE was used for separation and protein quantification was performed by computer densitometry. A significant effect of the variety on individual gluten proteins was found. In the Pannonia variety, it has been found that the interaction of higher temperature and drought has no major effect on glutenin content and glutenin/gliadin ratio. The RGT variety was significantly affected by these conditions, resulting in a decrease in glutenin content and a significant change in ratio. In both varieties, the glutenin content was higher when cultivated at higher humidity but only at two higher cultivation temperatures.
Basic chemical characteristics of cranberry juice
Cao, Ha Thuy ; Hrstka, Miroslav (referee) ; Vespalcová, Milena (advisor)
This bachelor thesis is about lingonberries and cranberries. It is mainly about berries which were used for chemical analysis. The berries are from the Research and Breeding Institute of Pomology Holovousy Ltd. and they have delivered six cultivars of lingonberries and three cultivars of cranberries. There is a research of general information about classification, botanical description, important chemical substances such as vitamins, natural colorants and products made in the industry. Furthermore there is descriprion of chemical methods for basic analysis. The next part of bachelor thesis is about how all these methods were applied to berry juice. What instruments and chemicals were used. First assessment was profit of juice which was about 50,00–60,00 %, but lingonberry Runo bilawskie has at least 31,49 % and cranberries have less profit too. Total solids were determined in the range of 11,40 % (Pilgrim) to 18,50 % (Runo bielawskie) and solitable solids are in range of 10,00 % (Pilgrim) to 16,08 % (Korál). Lingonberry contains more reducing sugars (8,81–12,92 %) than cranberry (7,90–9,03 %). Titratable acids are about 32,04–49,60 mmol.l-1 for lingonberry and about 55,40–60,67 mmol.l-1 for cranberry. The measurements show that pH of both berries are about 3. The most phenolic substances are found in range of 2187,11–3476,75 mg.l-1. Berries content anthocyans colorants in range of 54,91-65,29 mg.l-1 and the most in cranberry. All results are shown in charts and in the end there is a discussion and conclusion about methods and results.
Changes in the content of gliadin protein fractions in two genotypes of winter wheat with different lengths of vegetation time in response to an elevated concentration of carbon dioxide.
Janíčková, Vlasta ; Vítová, Eva (referee) ; Hrstka, Miroslav (advisor)
This diploma thesis deals with an influence of elevated concentration of carbon dioxide (700 mol·mol-1) on the protein content of gliadin fraction in winter wheat (Triticum aestivum) early var. Avenue and late var. Tobac. To separate gliadin, the A-PAGE method was used, proteins were quantified by computer densitometry. Signitificant influence of genotype on the gliadin fraction of the gluten proteins was found. Due to the increased concentration of CO2, the content of the gliadin fraction of the Avenue variety was reduced, while the content of the gliadin fraction of the Tobac variety increased. Effect of elevated CO2 concentration was at var. Avenue showed a significant difference in total content of gliadin fraction and fraction 1,2-gliadins. A significant difference was found in the var. Tobac only in the fraction 1,2-gliadin.
Changes in the content of gliadin protein fractions in two genotypes of winter wheat with different lengths of vegetation time depending on nitrogen fertilization with drought interaction.
Francová, Marie ; Zemanová, Jana (referee) ; Hrstka, Miroslav (advisor)
In this diploma thesis the influence of the nitrogen fertilization and drought on the change in the content of gliadin protein fractions in two genotypes of winter wheat Avenue and Tobac was studied. These two genotypes differ in vegetation time length. Half of the plants were fertilized using nitrogen fertilizer at 200 kg N/ha. One third of the plants were cultured under the conditions of early drought (in bloom season), other one third was grown under the conditions of of late drought (grain filling season), and last third was grown under the conditions of natural irrigation. Individual gliadin fractions were separated by using A-PAGE method and their content quantified by computer densitometry. Our results have shown increase in gliadin fractions content after nitrogen fertilization. Early drought itself caused significant increase in the levels of -gliadin fractions in Tobac genotype. Early and late drought in combination with nitrogen fertilization increased levels of gliadin fractions in Tobac genotype. Early drought in combination with nitrogen fertilization had no effect on Avenue genotype, except of -gliadin fractions which decreased significantly. Late drought in combination with nitrogen fertilization caused significant increase in gliadin content in Avenue genotype. The highest increase in gliadin content was observed in fraction -5 of the Tobac variety during interaction nitrogen fertilization with late drought.
Changes in gliadin content in four varieties of wheat at different temperatures and drought stress.
Cigánková, Michaela ; Kovalčík, Adriána (referee) ; Hrstka, Miroslav (advisor)
This diploma thesis deals with an influence of increasing temperature and water shortage on the content of gliadin proteins in four varieties of wheat: Bohemia, Pannonia, Tobak and RGT Reform. Samples were cultivated at 26, 29, 32, 35, 39 and 41 ° C. Due to the lack of culture samples at 41 ° C, these samples were not used for our experiment. Cultivation took place during flowering with sufficient moisture (with soil moisture higher than 70%) or under drought stress (with humidity below 30%). The A-PAGE method was used to separate gliadin fractions. Quantification was performed by computer densitometry. Significant influence of water availability on gluten protein content was found. The lack of moisture in the stress environment caused a relative increase in gliadin fractions compared to conventional conditions, especially in the Pannonia and RGT Reform varieties. The Pannonia and RGT Reform varieties responded most to the temperature, while Bohemia. The Tobak variety responded to the temperature in interaction with water scarcity. Due to the rising temperature, virtually all gliadin fractions in the Pannonia and RGT Reform varieties increased. The effect of drought often manifests itself in interaction with the influence of temperature. The most dramatic effect was the drought in interaction with temperature in the Tobak variety, where the gliadin content increased. In general, the temperature and drought were most affected by -gliadin fractions of all four varieties of wheat.
Preparation and expression of p53 protein isoforms using the GATEWAY expression system
Wikarská, Monika ; Hrstka, Miroslav (referee) ; Brázda, Václav (advisor)
The TP53 gene can express protein p53 and 11 another isoform proteins N- and/or C-terminally truncated by using two promoters and alternative splicing. The p53 isoforms are found in both healthy and tumorous tissues, and are intensively studied in relation to cancer diagnosis, prognosis and treatment. In this work, the p53 isoforms were subcloned into expression vectors by LR reaction adapted from Gateway cloning system. The expression vectors were designed for protein production by bacteria E. coli strain BL-21. The constructs containing p53 isoforms were encoded together with two fusion proteins, glutathione-S-transferase and polyhistidine tag under the control of the same promotor for the affinity chromatography protein isolation. All the clones underwent Sanger sequencing for verification after homologous recombination. Sequencing confirmed the accuracy of the subcloned isoforms p53, 133p53, 160p53, p53 and 160p53 into an expression vector pDEST15-N6xHis-GST-GW-DEST. Protein 160p53 was expressed in BL-21 and isolated using both HIS and GST tag interacion. Isolation using HIS tag yielded in a higher protein concentration then the isolation mediated by the interaction of the glutathione-S-transferase.
Comparison of the properties of chokeberry spreads of different origins, comparison and different production technologies
Kapiton, Ulyana ; Hrstka, Miroslav (referee) ; Vespalcová, Milena (advisor)
This diploma thesis deals with comparison of the properties of chokeberry spreads of different origins, composition and different production technologies. The theoretical part contains a brief description of the chokeberry – Aronia melanocarpa, an overview of the most important substances contained in the chokeberry and examples of the use of aronia, not only in the food industry. Furthermore, the legislative requirements for the production of spreads and the production technology itself are described. In this thesis is also described a new patented technology of spread production using HTD technology. Another part of the theoretical part is a literature review of the determination of anthocyanins in chokeberry by HPLC method. The experimental part describes the laboratory procedures used for determination of dry matter, carbohydrates by HPLC with ELSD detector, anthocyanin dyes, total phenolic compounds and antioxidant activity. Another part of the work was a questionnaire survey and sensory analysis of selected chokeberry spreads. The panel members prefered the Lowicz chokeberry spread, for which was determined 29,39% dry matter, 15,15 mg.g-1 anthocyanins, 9,20 mg.g-1 total phenolic compounds, 158,42 mg.g-1 fructose and 151,26 mg.g-1 glucose and the antioxidant activity was determined to be 5,94 mg.g-1.
Evaluation of Fracture Mechanical Parameters for Bi-Piezo-Material Notch
Hrstka, Miroslav ; Materna, Aleš (referee) ; Náhlík, Luboš (referee) ; Profant, Tomáš (advisor)
Předkládaná dizertační práce se zabývá stanovením hlavních členů Williamsova asymptotického rozvoje popisujícího rovinné elektro-elastické pole v okolí piezoelektrických bi-materiálových vrubů a trhlin na rozhraní za použití rozšířeného Lechnického-Eshelbyho-Strohova formalismu v návaznosti na čistě anizotropní pružnost. Je ukázáno, že rozšířený Lechnického-Eshelbyho-Strohův formalismus představuje spolu s moderními programovacími koncepty v jazyku Python efektivní a také praktický nástroj pro lomovou analýzu piezoelektrických bi-materiálů. Teoretická část práce popisuje aspekty anizotropní pružnosti a její návaznost na piezoelektrické materiály. Základní rovnice zaměřené na speciální typy monoklinických materiálů, které umožňují oddělení rovinného a anti-rovinného problému, jsou vyjádřeny pomocí komplexních potenciálů. V praktické části práce je sestaven problém vlastního hodnot pro bi-materiálový vrub, na jehož základě jsou stanoveny exponenty singularity a pomocí dvoustavového -integrálu také zobecněné faktory intenzity napětí. Veškeré vztahy a numerické procedury jsou následně rozšířeny na problém piezoelektrických bi-materiálových vrubů a podrobně prozkoumány v uvedených příkladech. Zvláštní pozornost je věnována přechodu asymptotického řešení téměř zavřených vrubů a trhlin na rozhraní. Vliv směru polarizace na asymptotické řešení je také zkoumán. Přesnost stanovení zobecněných faktorů intenzity napětí je testována srovnáním asymptotického řešení a řešení získaného pomocí metody konečných prvků s velmi jemnou sítí konečných prvků. Na závěr je formalismus modifikován pro nepiezoelektrické materiály.

National Repository of Grey Literature : 111 records found   1 - 10nextend  jump to record:
See also: similar author names
1 Hrstka, M.
Interested in being notified about new results for this query?
Subscribe to the RSS feed.