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The influence of caffeine on the change of reaction time.
BAUEROVÁ, Miroslava
Thesis is focusing on influence of caffeine on the change of reaction time of individual. The theoretical part consists of the introduction of the specific subject and is following by information about positive and negative caffeine effect on the human body. Certain part of dissertation presents some liquid food products, where caffeine is included. The description of the reaction time of the individual before and after consumption is mentioned as well. The practical part of thesis pays attention to the experimentation with the pre-selected sample of person. The test itself was based upon usage of the reaction measurement tool with the optical stimulus for inputs. The objective of the practical part was to compare the influence of caffeine, and its specific amount, on the reaction abilities of selected individuals. Recorded data have been than statically evaluated, and prepared to final comparison. Based on receiving information the unequivocal deduction was determined.
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Interaction between TiAl melt and coated oxide refractories
Dočekalová, Kateřina ; Dlouhý, Antonín ; Zemčík, L. ; Fiala, J.
The present study focuses on reactions between ceramic crucibles and molten TiAl intermetallics. Coating strategies are investigated that exhibit a potential in slowing down the decomposition of the crucible wall. Uncoated crucibles (system TiAl melt - Al2O3 crucible) and crucibles with the coat (system TiAl melt - CaO coat - Al2O3 crucible) were used in melting and casting experiments. The reference state of the coated crucible before the melting trial was also investigated. Results of the SEM, EDAX and X-ray diffraction analysis contributed to the identification of the reaction zone and its chemical composition. The melt contamination with oxide inclusions results from the erosion process in which individual components of the melt diffuse along grain boundaries of the refractory and activate chemical reactions that decompose the crucible wall. Assessment of thermodynamic parameters associated with the chemical reactions helped in identifying the nature of the erosion process.
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Study of the synthesis and structure of ceramic perovskite materials for energy applications
Strejček, Josef ; Bartoníčková, Eva (referee) ; Cihlář, Jaroslav (advisor)
Method, so called “glycin- nitrate process”, combined with high temperature solid state reaction, of preparation multi- component ceramic perovskite materials was studied. Two types of perovskite systems were prepared by this method. Firs one, based on LaNiO3 doped by calcium and aluminium and second one, based on SmFeO3 doped by calcium and nickel or cobalt. This method made possible preparation of one phase perovskite or perovskites with few percent of nickel in form of oxide. In systems containing both nickel and calcium another phases rich in calcium and nickel appeared.
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The optimization of phosphate binders compozition used for refractories
Kalousová, Hana ; Ptáček, Petr (referee) ; Opravil, Tomáš (advisor)
This thesis deals with optimization of the composition phosphate binders. These binders are used in production of refractories. In this branch, the bauxite is very often used as an aggregate, but it contains tiny particles of iron which arise in milling process. These particles of iron react with the phosphate binder to form hydrogen – it is consequence of the reaction between phosphoric acid and iron. The formed gas causes the formation of bubbles and the deformation of refractories. The goal of this thesis is to find suitable additives which can be used to stop or to limit the production of hydrogen. Usually used binders were replaced by a model binder to simplify the system and for better understanding. The model binder was prepared in laboratory by dissolving aluminium hydroxide in phosphoric acid. They used pure powdered pentacarbonyl iron instead of tiny iron particles from the milling process. The model binder was modified with using a few inhibitors. The calcimetr was used to measure their influence on the production of hydrogen, as well as measuring concentrated rows of selected inhibitors. These rows are necessary to optimize the inhibitors quantity added in the binder.
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Variable geometry of intake and exhaust ports of Wankel engine
Krejčí, Tomáš ; Beran, Martin (referee) ; Zháňal, Lubor (advisor)
The purpose of this thesis is to design the key parameters of the high-powered Walkel engine and to design a chamber side on the base of computed parameters so that it enables variable change of the intake and exhaust port geometry. Consequently, to carry out a flow simulation in both ports in designed chamber side in order to find out its flow character and geometry change reaction.
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Modelling of Phase Composition of Heat Resistant Steels and their Welds
Dvořáček, Ondřej ; Foret, Rudolf (referee) ; Jan, Vít (advisor)
This work deals with the effects of high temperature exposition of low alloyed creep resistant steels on their structural stability and structural stability of their weld joint. The theoretical part of this work gives an overview of creep resistant steels considering their chemical and phase composition and their connection to high temperature mechanical properties. The CALPHAD method is presented as generally accepted approach for equilibrated calculations and Thermo-Calc and DICTRA software packages are introduced as CALPHAD applications. Thermo-Calc software is used for calculation of phase composition of the examined materials and for calculation of the phase diagrams. Software DICTRA is used for simulations of diffusion controlled phase reactions in the analysed weld. Experimentally one weld joint of the steels 15 128 and 15 313 has been studied after four different annealing procedures. The experimental results include chemical profiles across the welds, microhardness profiles and metallographic analysis of significant regions of the welds. These experimental results are compared with the simulation results. The comparison shows a reasonable agreement between experimental and simulation data.
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Synthesis and cytostatic activity of 3,5-disubstituted pentenolides analogous to gelastatin
Pavlík, Jan ; Pour, Milan (advisor) ; Starý, Ivo (referee) ; Dvořák, Dalimil (referee)
Within the framework of this thesis, a large series of 5-(acyloxymethyl)-3-aryl-5,6- dihydro-2H-pyran-2-ones was prepared and their cytostatic activity investigated. The key steps in the preparation of the compounds were alkylation of esters of substituted phenylacetic acids with 2-iodomethyl-5,5-dimethyl-1,3-dioxane, followed by cyclization to furnish a saturated lactone into which a double bond was introduced in the next step. Some of the target compounds displayed interesting cytostatic activity (IC50 < 10 µmol/L) against a panel of standard cell lines including both leukemic cells and those derived from solid tumours. The activity against colorectal carcinoma HT29 cell line, which is otherwise resistant against the standard combination of cytostatic agents used in the treatment of these tumours is especially remarkable. In the next part, the development of the synthesis of the 5-alkylidene analogues of these compounds, which are also analogous to bioactive natural products, such as the gelastatins and CR377, is described. Successful strategy is based on the use of 2-iodo allylic alcohols as the starting materials, which are converted into the target 3-substituted-5-alkylidene pentenolides via an array of Pd-catalyzed reactions, including Sonogashira coupling with methyl propiolate,...
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Information content in vocalization of guinea pigs (Cavia porcellus): individual distinction and recognition of predators
Baklová, Aneta ; Baranyiová, Eva (advisor) ; František, František (referee)
Guinea pigs represent domesticated precocious rodents which became common pets. From the first day after birth they are fully vocal. This thesis was devoted
to the vocalization of pups. The aim of the thesis was to 1) determine the age when the vocal individuality in whistle sound is demonstrable; 2) test possible ultrasonic signals emitted by young guinea pigs; 3) study the antipredator reactions and alarm calls to aerial (bird of prey) and terrestrial (dog) predators and human (control test).
A total of 16 guinea pig pups were tested for vocal individuality, 28 pups
for ultrasonic vocalization and 27 adolescents for predator recognition. When testing vocal ontogeny during the first 9 days after birth, I observed changes in temporal, frequency and parameter of intensity . When I test vocal individuality by cross-validated discriminant function analysis (DFA) based on ten acoustic parameters, calls were classified to correct animals with following success: day 1 = 71.9%, day 3 = 58.8%, day 5 = 53.10%, day 7 = 50.60% and day 9 = 63.10%. The highest frequency in whistle was 30.03 kHz. In predator discrimination reactions as freezing, fleeing and vigilance were observed. In the presence of dog, guinea pigs reacted for the longest time and most frequently by freezing. When confronted with a bird of prey, I observed for a longest time and most often fleeing and then freezing. When exposed to a human, guinea pigs showed mostly vigilance. Almost no vocalization was observed except for two events
of alarm calls - drrr as in the presence of dog and chirrup as reaction to bird of prey.
The following conclusions can be drawn from the presented results: 1) vocal individuality of guinea pigs is demonstrable immediately after birth and the rate
of individually different vocal parameters changes with age; 2) guinea pigs are able
to produce sound up to 30 kHz, i.e. within the ultrasound range, but signals of high frequencies are not crucial for their communication; 3) guinea pigs discriminate between terrestrial and aerial predators, but they emit alarm calls rather rarely.
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Steam generator for nuclear power plant with fast reactor
Karička, Radoslav ; Nesvadba, Lukáš (referee) ; Šen, Hugo (advisor)
The aim of the project is to design a steam generator in which the sodium flows pipeline hand, and on the other hand, water flow and water vapor (H2O). The main idea of this thesis is to propose such a steam generator, to avoid or eliminate the possibility of adverse reactions of sodium with water and, if this phenomenon occurs, thus minimizing the damage caused by this reaction. The work contains information on the implementation of steam, steam option, the necessary calculations for the design and construction and evaluation.
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