National Repository of Grey Literature 460 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Effect of temperature on arrhythmogenesis during heart development
Vostárek, František
5 Abstract: Aims: The main objective of this work was to analyze in detail the effects of acute temperature changes on the function of isolated chick embryonic heart in vitro in comparison with natural conditions in ovo. Methods: The effects of temperature change (34 řC, 37 řC and 40 řC - hypo-, normo- and hyperthermia, respectively) on calcium dynamics in four days old isolated chick hearts in vitro were investigated by high-speed calcium optical imaging. For comparison and validation of in vitro measurements, experiments were also performed in ovo using videomicroscopy. Artificial electrical stimulation experiments were performed in vitro and in ovo to uncover conduction limits of different heart segments. Results: We observed almost linear dependence of sinus frequency on temperature in our temperature range. Sinus frequency during hypothermia and hyperthermia in vitro and in ovo changed about 20% in comparison with normothermia. We observed no significant changes in amplitude of calcium transients during temperature change to hypothermia but hyperthermia caused a significant decrease in amplitude of calcium transients (atria 35%, ventricles 38%). We observed a wide spectrum of arrhythmias, which occurred spontaneously even during normothermia in vitro. Occurrence of arrhythmias in vitro significantly...
Air quality in buildings
Kops, Tomáš ; Uher, Pavel (referee) ; Rubinová, Olga (advisor)
The aim of the diploma thesis is to find out by measuring the production of carbon dioxide that man produces in various types of physical activity. Using the model, the goal is to simulate real carbon dioxide production for a type object and to design a way of automatic regulation, air supply and drainage to obtain better indoor environment (represented by carbon dioxide).
Optimization of ventilation in the production hall
Myjavec, Patrik ; Uher, Pavel (referee) ; Blasinski, Petr (advisor)
Diploma thesis is divided into two parts. The theoretical part deals with natural ventilation and the practical part focuses on the optimization of the ventilation in the original hall using CFD simulation. One of the solutions is proposed in the design part of the diploma thesis.
Temperature changes in thin films of nanoparticles
Krtouš, Zdeněk ; Kousal, Jaroslav (advisor) ; Hanuš, Jan (referee)
Many properties of nanoparticles are different from general bulk properties. This work is focused on coalescence of nanoparticles depending on temperature.Coalsescence was experimentaly measuered on gold nanoparticles, copper nanoparticles and silver nano- islands.The samples were characterised by SEM, AFM and in-situ ellipsometry in range between 20řC and 350 řC. In the theoretical part was analyzed existing semi-analytical model of coalescence and then it was created a new model based on previous one. In the end, the comparison between experimental data and model was done. New model predicts greater coalescence of nanoparticles, what corresponds to experimental data.
Volumetric and electrostatic properties of water and their application to aqueous thermodynamics and mineral solubility at high temperatures and pressures
Hanková, Barbora ; Dolejš, David (advisor) ; Zachariáš, Jiří (referee)
Hydrothermal fluids are important mass and heat transfer agents in the Earth's crust and mantle. Aside from their transport role, the aqueous fluids act as reactants or products in rock environment during diverse processes ranging from partial melting, magmatic and metamorphic devolatilization. This study evaluates the effect of equations of state and thermodynamic data for aqueous species on prediction of mineral solubility in aqueous fluids at high temperatures and pressures employing the Helgeson-Kirkham-Flowers model (HKF). These calculations require: (i) volumetric properties of water; (ii) dielectric properties of water; (iii) aqueous species thermodynamic properties. A comparison of ten equations of state against the IAPWS scientific standard reveals that volumetric properties of water up to 1200 řC and 50 kbar are predicted within 5 %, except at low pressure (below 2 kbar), temperatures higher than 1000 řC, and the liquid-vapor equilibrium curve, particularly in the proximity of the critical point of water. The deviations of volumetric and electrostatic properties of water propagate into the mineral solubility calculations. For quartz and corundum these deviations lead to discrepancy in mineral solubility of up to half an order of magnitude for molal concentrations. These discrepancies...
Trends of hydroclimatic factors in selected catchments of the Ore Mts.
Navrátilová, Denisa ; Matoušková, Milada (advisor) ; Fraindová, Kateřina (referee)
The bachelor work deals with identification of the trends in data series of the chosen hydroclimatic factors (temperatures, rainfall and runoff) of the upper Svatava River basin and of the Načetín Brook which both drained the Ore Mountains. The main aim of the thesis is identification of the trends of both study catchments and their comparative analysis. The study uses mean daily discharges data from the gauging stations Klingenthal and Rothenthal and also from the German climatic stations situated near study catchments. The introductory part describes physical-geographic characteristics of study catchments. The main attention is paid to the analysis of temperatures, rainfall and runoff, e.g. by the method of linear regression, simple sum curves and by Mann-Kendall statistic test. More detailed analysis of the runoff was done using IHA software. Results of analysis show a significant annual trend of temperatures increasing and runoff decreasing during the examined period. The most significant changes in temperatures and runoff is recorded in the spring and summer seasons. Key words: outfall, rainfall, temperatures, the change of the rainfall-outfall régime, Mann- Kendall test, IHA analysis
Influence of Water-Ethanol-Modified Supercritical Carbon Dioxide at the Preparation of Crystalline Monolithic TiO2 Aerogels.
Cerhová, Marie ; Sajfrtová, Marie ; Matějová, L. ; Dřínek, Vladislav ; Daniš, S. ; Jandová, Věra
This work is focused on a study of TiO2 aerogel SFC with scCO2 modified by mixture of ethanol and water in a ratio 1:1. The effect of temperature (40-100 °C), pressure (10-30 MPa) and modifie concentration in scCO2 (5-15 wt.%) and the additional drying with pure CO2 on microstructure, purity and textural properties of TiO2 aerogel was investigated. Processed monoliths were characterized by XRD analysis, Raman spectroscopy and N2 physisorption.
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Non-Thermal Crystallization of TiO2 Thin Films using Supercritical Carbon Dioxide Modified by Ethanol-Water Mixture.
Sajfrtová, Marie ; Cerhová, Marie ; Jandová, Věra ; Dřínek, Vladislav ; Matějová, L. ; Daniš, S.
In this work, the scCO2 modified by mixture of water and ethanol was used for a preparation of crystalline and pure nanostructured TiO2 thin films in one step processing. All the experiments were performed over precursor titania thin films prepared by reverse micelles assisted sol-gel method, using hardly removable nonionic surfactant Triton X-114, however, forming uniform nano-domains. The effect of temperature (40-150 °C), pressure (10-30 MPa), modifier composition \n(20, 50 and 80 % w/w of water in ethanol) and concentration inscCO2 (5-15 wt. %) and consumed amount of solvent (50-200 g) on microstructure and purity\nof TiO2 thin films was thoroughly studied by means of Raman spectroscopy, X-ray diffraction, and contact angle measurements.
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Influence of the mixing plant manufacturing temperatures on the properties of aggregates
Brtníková, Tereza ; Stehlík, Dušan (referee) ; Hýzl, Petr (advisor)
The bachelor thesis describes the production process of aggregate and production process of asphalt mixing in batch asphalt mixing plant. There is also mentioned the test procedure of endurance against grind and against freezing and defrosting. The tests were did on 3 types of rocks, which have been burdened by temperature on 110 °C, 200 °C and 300 °C. Then were the results compared.
Device for Honey Bee Activity Measurement
Fučík, Jan ; Šimíček, Tomáš (referee) ; Novák, Marek (advisor)
This thesis engages in characteristic honey bee's behaviour first. Subsequently it engages in project of device for honey bee activity measurement. It reasons about non-electric quantities which can honey bee's behaviour represent. Description of components which can be use for measure these quantities follows. Description is intent on possible accuracy and energy consumption of each component. Appropriate method is selected subsequnetly. In realitionship with method are selected sensors and projected controlling circuit. There is a summary of parameters of device in resume. There is also design of the parts which do not work as good as is ideal in resume.

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