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Impact of temperature and drought on gliadins and glutenins contents in four varieties of wheat
Tomasz, Teresa ; Vítová, Eva (referee) ; Hrstka, Miroslav (advisor)
This diploma thesis deals with an influence of high temperature and water shortage on the protein content of gliadin and glutenin fractions in four varieties of winter wheat: Bohemia, Tobak, Pannonia and var. Syria with designation S46 (IG142780). The crop was grown at 26, 29, 32, 35, 38 and 41 °C during anthesis under control irrigation treatment (with soil moisture higher than 70 %) or under drought stress (with soil moisture lower than 30 %). To separate gliadins, the A-PAGE method was used, and glutenins were separated by SDS-PAGE method. Proteins were quantified by computer densitometry. Significant influence of genotype on the gluten proteins was found. Variety Pannonia has high content of -, 5-gliadins, LMW and HMW glutenins, but low content of other gliadin fractions. It was the opposite in the other varieties. Due to temperature, as well as drought, there was an increase in the content of all gluten fractions, especially of HMW glutenins, 1,2-gliadins and total gliadins. The largest increase in the gluten fractions due to drought was observed in Syria variety. In other varieties simultaneous exposure to drought and heat caused decrease in gliadin content, but increase in glutenin content. Drought at high temperatures reduced gliadin-to-glutenin ratio, mostly in Bohemia variety. This ratio has increased due to the temperature, especially in Tobak variety. For Syria variety, no effect of stress conditions was found on gliadin-to-glutenin ratio.
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Assessment of chosen aroma compounds in foods and cosmetics
Obrdlíková, Blanka ; Hrstka, Miroslav (referee) ; Vítová, Eva (advisor)
This diploma thesis is focused on the problematic of assessment of allergenic aroma compounds in various matrices. In the frame of European legislation 26 of potentially allergenic compounds are stated, whose content in cosmetic products is limited. In the case of foods there is not such restriction so far. In the experimental part, the allergenic aroma compounds in chosen samples of cosmetic and food samples were identified and quantified using Solid phase microextraction in conjunction with gas chromatography. Sensory evaluation of aroma or taste is also included.
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The possibilities of assessment of free fatty acids in food matrix
Brožová, Michaela ; Hrstka, Miroslav (referee) ; Vítová, Eva (advisor)
This bachelor´s thesis has a research character and deals with the possibilities of determination of fatty acids in foodstuffs, mainly focused on dairy products. It starts by overview of general characteristics of lipids and fatty acids. The crucial part of thesis represents summary of the methods, which can be used for determination of fatty acids. A special chapter is devoted to determination of free fatty acids. The isolation of lipids/fatty acids from sample matrix is necessary before the determination itself, classic solvent extraction in various applications or several new extraction techniques, e.g. solid phase extraction or supercritical fluid extraction, can be used for this purpose. After the separation of individual lipid fractions, for which the solid phase extraction and/or thin layer chromatography are usually used in practice, the transformation of fatty acids to derivatives, which are suitable for following analytical determination, is often necessary. Gas chromatography with the flame-ionization or mass selective detection is most often used for determination and therefore fatty acids are converted to substantially more volatile methyl esters. In some special cases high performance liquid chromatography and/or thin layer chromatography can be used.
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Monitoring of arsenic forms in foodstuffs
Harkabusová, Veronika ; Hrstka, Miroslav (referee) ; Vitoulová, Eva (advisor)
The diploma thesis is dealing with monitoring of arsenic in foodstuffs. The aim of this thesis is the determination of arsenic in samples of fish and rice and the study of forms, in which arsenic occurs, using speciation analysis. Arsenic is known as a toxic element, but its measure of toxicity depends on the chemical form it occurs in. Arsenic is present in the environment naturally or it gets in the environment by human activities. Complete characterization of arsenic compounds is necessary to understand intake, accumulation, transport, detoxification and activation of this element in the natural environment and living systems. The field of arsenic speciation analysis has grown rapidly in recent years, because determination of the total element content is not sufficient in the case of arsenic. Speciation method was done using separation by high performance liquid chromatography and detection by atomic fluorescence spectrometry with hydride generation. Extractable arsenic was present in the form of nontoxic arsenobetaine in all analysed samples of fish. In samples of rice there was confirmed the presence of toxic inorganic species of arsenic, esspecially As (III), but their concentration was at low level.
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Strength-strain analysis of dog prosthesis
Doležalová, Veronika ; Hrstka, Miroslav (referee) ; Vlach, Radek (advisor)
Bachelor thesis deals with strength-deformation analysis of dog prosthesis. Work contains introduction to problems of prosthesis and determination of kinematice during dog’s movements. The analysis was carried out using two approaches, both analytical and numerical. In conclusion, we compare the results of both computational approaches.
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Calculation of the dynamic behavior of the rotor using the method of transfer matrices
Kratochvíl, Filip ; Hrstka, Miroslav (referee) ; Lošák, Petr (advisor)
The master‘s thesis deals with the modelling of a rotor using the transfer matrix method and the displacement method. Specifically, it addresses the response to static loading, the first natural bending oscillation shape and the response to imbalance. The focus of the review is on the transfer matrix method and its practical applications in various parts of dynamics. The method of rotor modelling and the various elements used for this purpose are also described. The first practical part focuses on the static response of the rotor to self-weight and external loads. This is solved based on the transfer matrix method. The next part deals with finding the rotor's natural speed based on the transfer matrix method and the displacement method. For this purpose, two different approaches have been used depending on the method. For the transfer matrix method, the interval halving approach was chosen and for the displacement method, the eigenvalue problem was solved. The last practical part is the solution of the response to imbalance. This was done based on the displacement method. At the end of the thesis, a control example is performed where the derived solution is compared with the solution using the finite element method.
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Analysis of the frontloader arm pin
Smolek, Jan ; Lošák, Petr (referee) ; Hrstka, Miroslav (advisor)
This bachelor's thesis focuses on the dynamic stress analysis of the Stoll FZ 41-33 tractor front loader. It was important to include the inertial effects and loading of the loader in the analysis. For the solution, a program was created in the Python programming language, where the vector and relaxation method of solving mechanisms was used. The result is the courses of forces acting at the nodal points of the loader depending on the time of the analyzed mo-vement. It is possible to simply implement other external influences into the created program or change the characteristic dimensions to a different type of loader. A partial result was also a finite element analysis of the pivot-cantilever node, where the finite element method was used in the Ansys Workbench program. The outputs of this work can find real use in practice in the development of tractor front loaders.
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