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Optimation of inoculation process of ductile iron
Ulm, Daniel ; Pecina, Vladimír (referee) ; Roučka, Jaromír (advisor)
The master‘s thesis deals in theoretical part with the casting classification, ductile iron casting, its inoculation and modification and quality evaluation using thermal analysis, image analysis and testing of mechanical properties. The aim of the practical part was to test the effects of preconditioning on the properties of ductile iron and to find out whether it is able to replace the current method of inoculation or to increase the mechanical properties of ductile iron castings. The state of the ductile iron was under control by spectral and thermal analysis. The mechanical properties and image analysis were checked on finished casting.
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Determination of binary phase diagram
Dobeš, Pavel ; Havlík, Petr (referee) ; Jan, Vít (advisor)
This bachelor's thesis deals with the analysis and verification of binary diagram of the Ag-Sb system. The theoretical segment of the thesis describes the sub-elements of this system, the function of binary diagrams and the methods of thermal analysis. The experimental segment mainly deals with the interpretation of DSC signal, the analysis of the microstructures of specific Ag-Sb system samples and the comparison of the acquired data with the given binary diagram.
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Analytical methods for determination of polyhydroxyalcanoates content in bacterial cells
Černayová, Diana ; Enev, Vojtěch (referee) ; Sedláček, Petr (advisor)
This bachelor thesis deals with methods that are used for determination of polyhydroxyalkanoates (PHA) in cells of bacteria Cupriavidus necator H16. To the applied methods belong Fourier transform infrared spectroscopy, Raman spectoscopy, turbidimetry and thermal analysis (thermogravimetric analysis and differential scanning calorimetry). The results of each method were compared to amount of PHA determinated by gas chromatography. Fourier transform infrared spectroscopy and Raman spectroscopy revealed a linear relation between ratio of characteristic peaks and amount of PHA. FTIR enabled to determine not only the quantitative amount of PHA, but the quality of the sample (cristallinity, amorphous state) as well. Another method was turbidimetry, which has shown correlation between dispersion of UV-VIS light to amount of PHA in bacterial cells. Thermogravimetric analysis was the most effective technique for determination of PHA. The dependence of weight loss of PHA on its content (found by gas chromatography) was determined with the highest accuracy to gas chromatography. Tha last method- DSC was not alternative replacement for quantitative PHA determination. However, DSC indicated crystalline and amorphous state of the polymer.
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Design of rotating rectifier for synchronous generator
Skurka, Tomáš ; Cibulka,, Tomáš (referee) ; Ondrůšek, Čestmír (advisor)
This diploma thesis is focused on the design of a rotating rectifier for a synchronous generator. Based on defined requirements, the new rotating rectifier concept has been created that allows a greater current range than existing rectifier used by Siemens Electric Machines s.r.o. The thesis is divided into five parts. The first part deals with the search of existing rotating rectifiers and other design possibilities. The requirements for the rotating rectifier were defined in the second part of the thesis. The following section deals with both electrical design of rectifier elements and varistors. The fourth part of the diploma thesis describes the thermal analysis. On the basis of thermal analysis the operating conditions of the rotating rectifier were determined. The last part of the thesis is devoted to mechanical and modal analysis. Based on these analyses, the strength and operability of the new rotating rectifier concept were verified.
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Composition and microstructure of plasters in convent of the Želiv Monastery (Czech Republic)
Rezek, P. ; Martinec, Petr ; Ščučka, Jiří ; Majstríková, T.
The paper deals with analyses of composition and structure of historic plasters from the convent building of the Želiv Monastery (Czech Republic). Composition and microstructure of plaster samples taken from the historic object have been assessed using both traditional and advanced analytical methods. The following techniques have been used for the assessment of binders and fine aggregates in plasters: optical microscopy of thin sections, mineralogical and petrographic analysis of separated components, infrared spectroscopy, and thermal analysis. Presented results show significant differences in character of the studied materials of varying age and demonstrate the effectiveness of the taken analytical approach.
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Solid dispersions with terbinafine
Hluchníková, Nikola ; Šnejdrová, Eva (advisor) ; Dittrich, Milan (referee)
CHARLES UNIVERSITY Faculty of Pharmacy in Hradec Kralove Department of Pharmaceutical technology Name of the student: Nikola Hluchníková Title of diploma thesis: Solid dispersions with terbinafine Consultant: PharmDr. Eva Šnejdrová, PhD. The diploma thesis deals with the release of terbinafine base and terbinafine hydrochloride from degradable carrier in three different mediums. The carrier was polyester of lactic acid and glycolic acid branched on polyacrylic acid. The theoretical part is focused on the description of properties of drug substance and branched polyester, the bioavailability of poor soluble substances, the types of polymeric carriers and the release of drugs from solid dispersions, the thermal analysis of polymer, drug and the solid dispersion with the incorporated drug. In the experimental part, solid dispersions were prepared by the melting method, dissolution of the drug in water, phosphate buffer pH 5.5 and pH 7.4 were studied. The amount of released drug was determined spectrophotometrically at 223 nm and HPLC. A thermal analysis of polyester carriers and solid dispersions was performed by the DSC. The amount of drug released was affected by the pH of the environment. Prolonged release of terbinafine hydrochloride is carried out in a pH 7.4 phosphate solution. In case of...
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Calculation of the cooling of the asynchronous machine ANSYS CFX
Horálek, Lukáš ; Veselka, František (referee) ; Janda, Marcel (advisor)
The issue this master’s thesis discusses the cooling synchronous machines. Specifically, the calculation of cooling induction motor using the finite volume method. Using Autodesk Inventor will create a 3D model of a real electric machine, ie asynchronous motor and then ANSYS WORKBENCH perform system analysis CFX, based on the finite volume method. Furthermore, we realize the air speed measurements on a particular machine and the individual results obtained by measuring and calculating the actual compared with each other. The master’s thesis also deals marginally with closely related to it. For the same machine model, we apply the calculation of the temperature fields using the finite volume method and them perform a thermal analysis. Next, we can carry out the measurement of the temperature on the motor itself and calculate the measured values and the measured compare each other.
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Utilization of thermal analysis in study on protein denaturation
Bošeľová, Miriam ; Pekař, Miloslav (referee) ; Sedláček, Petr (advisor)
This bachelor thesis deals with the use of techniques of thermal analysis in the study of thermal denaturation of proteins. As a model protein was chosen lysozyme. In the experimental part were used two methods of thermal analysis – differential scanning calorimetry (DSC) and temperature modulated differential scanning calorimetry (TMDSC). One of the objectives of the study was to determine the utility of DSC and TMDSC in the study of lysozyme denaturation and to futher characterize the results we can obtain from the individual methods. Another goal was the optimization of TMDSC. During optimalization of TMDSC heat-iso, heat-only and heat-cool modes were compared in 60 seconds and 100 second periods. By selected methods was observed denaturation of lysozyme. Denaturation of lysozyme is predominantly created by reversible component of the heat flow and the denaturation temperature is in the range of 71,16 °C to 75,21 °C depending on the set parameters.
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Preparation and Characterization of Mixed Hydrogels Based on the System Hyaluronan-Albumin
Hájovská, Pavla ; Kráčalík, Milan (referee) ; Kalina, Michal (advisor)
This diploma thesis deals with preparation and subsequent characterization of albumin (BSA) and mixed hyaluronan-albumin (HA+BSA) hydrogels. The experimental characterization was based on the rheological measurements of the influence of ionic strength, pH and molar mass of HA on the gelation process and the properties of formed gels, as well as the time stability of these properties. Following object of the study was swelling of hydrogels in water and buffers with different pH value. Characterization was extended by thermal analysis, morphology description using scanning electron microscopy (SEM) and study of transport properties of hydrogels for selected model substance. Due to increasing ionic strength, the gel point was shifted towards higher temperature values and the resulting gels exhibited higher values of complex moduli. In case when pH was lower than isoelectric point of BSA, attractive electrostatic interactions between albumin and hyaluronan took place and the faster gelation occurred, compared to the case when pH was higher than isoelectric point of BSA. On the contrary, values of complex moduli increased with increasing pH. The gel samples prepared in the presence of low molecular weight HA reached higher values of complex moduli, compared to samples with the high molecular weight HA. Rheological properties of BSA gels were stable over time, whereas the mixed HA+BSA were characterized by significant decrease of complex moduli during the first three days of storage. Due to heating up to 100 °C, more than 80 % of the weight of studied samples was lost, as a result of water evaporation. Further heating of hydrogels, up to 250 °C, did not cause other changes associated with weight loss, in contrast with crystalline powder BSA, in which another weight loss at 220 °C was observed, as a result of the beginning degradation. Swelling studies, as well as SEM images, indicated higher crosslink density of BSA gels, compared to HA+BSA samples, which exhibited higher values of swelling ratio. The lowest values of equilibrium swelling ratio were observed at pH 4, which is close to the isoelectric point of albumin. Calculated diffusion coefficients relative to diffusivity of methylene blue in water ranged between the order of 10E-2 for diffusion into physiological solution and the order of 10E-3 for the diffusion into water. Ongoing transport of model dye from gel to solution was significantly slower, compared to its diffusion in water, as a result of gel porosity and electrostatic immobilization of positively charged molecules of methylene blue on the negatively charged BSA and HA chains.
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