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Stability of soil organic matter and humic substances
Nováková, Šárka ; Enev, Vojtěch (referee) ; Klučáková, Martina (advisor)
This diploma thesis is focused on changes of stability in organic matter by extraction in different agents. Two soils of a different type and isolated humic acids were used for stability determination. Extraction agents were selected usually used for soil metal extraction, and a changes in the structure of the organic matter was observed. Samples were characterized using FTIR analysis and elemental analysis, the extracts were measured by UV-VIS spectroscopy, absorption ratios E2/E3, E4/E6 were discovered, dynamic light scattering were determined for particle size distributions. Next part of the thesis was the assessment of the change of thermal stability using thermogravimetric analysis and differential scanning calorimetry, degradation temperatures of the extracted samples were discovered and compared with the original samples.
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Tepelná stabilita pektinů
Vališová, Petra
Thesis on Thermal stability of pectins analyzes the physical properties of food hydrocolloids focusing on pectins. The theoretical part explains the general use of hydrocolloids in food with a detailed description of linear polysaccharide galacturonic acid. This part of the thesis pectins divides into groups according to various criteria, describes the mechanism of gel formation, explains the influence of various factors, and also shows the enzymatic reaction. The experimental part is focused on the physical parameters of selected types of pectins, depending on the time of warming and high temperature. The primary physical properties as viscosity, which was measured using a rotational viscometer and strength which was measured by a mechanical and digital penetrometer. This was measured thermal stability.
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The effects of vegetative roofs onto the thermal stability of a building object
Majsniar, Michal ; Moudrý, Ivan (referee) ; Vimrová,, Hana (referee) ; TROJAN,, Karel (referee) ; Šťastník, Stanislav (advisor)
Dissertation deals with thermal technical assessment songs vegetation roof with moisture, the more the influence of vegetation on the roof thermal stability of the structure. The aim of this work is to demonstrate the beneficial effect of vegetation roofs, specifically growing Formation of thermo-technical point of view on the favorable temperature conditions in the building. Such speech can be captured only if it is judged-temperature profile dynamically daily operation of real marginal climatic temperatures. Using a stationary or quasi-stationary boundary climatic temperatures which are usually used for the determination of the energy performance of buildings, said effect can not be collected. Demanding simulation calculation, which apply material properties - thermal conductivity, density and thermal capacity, but gives a realistic picture of the thermal processes in progress not only in the roof structure of the building, but also across the entire circuit construction of a building. During the preparation of the dissertation was assembled machine program that works with the energy flow between rooms in the building and the surrounding environment. Furthermore calculates temperature gain of residence of persons, internal lighting and sunlight. The values of the internal environment are calculated from surface temperature, relative humidity, air exchange and, of course, the indoor air temperature with hourly weather data. In constructing the program was included in the calculation of the solar radiation both on flat and on an inclined surface. The output of the energy value and temperature conditions in individual rooms, which include not only thermal insulation but also thermal storage properties of an object. Using experimental measurements were able to demonstrate that the calculated values closely correlate real thermal processes, so it can be demonstrated through the calculated results of the vegetation roof has a favorable effect on the thermal state espe
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Effect of clay plasters application on heat storage
Koukalová, Pavla ; Vlach, František (referee) ; Bečkovský, David (advisor)
The aim of this master thesis is a research of effects of clay plaster application and natural ventilation on heat storage of a room. In addition to theoretical analysis of basic characteristics of clay as material used in the field of civil engineering, an experimental verification of these characteristical features is carried out as well. The thesis also studies thermal comfort of a room in terms of humidity and concentration of CO2 in dependence of natural ventilation. In the last part, numerical verification of effects of clay plaster application on heat storage is calculated using Simulace 2015 software.
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Thermal degradation of hyaluronan
Šimáčková, Marcela ; David, Jan (referee) ; Chytil, Martin (advisor)
This diploma thesis investigated thermal stability and the degradation of hyaluronan (HA) in HA with a molecular mass of 90–130 kDa and in HA with a molecular mass of 1 500–1 750 kDa. The following methods were used for the research: rheology, SEC-MALLS, TGA and DSC. Low-molecular HA was subject to time dependency of degradation investigation, where it was dried at a temperature of 90 °C for a period of 30 minutes and 60 minutes prior to the preparation of the solutions itself. High-molecular HA was investigated not only from the point of view of time but from the point of view of temperature dependency of degradation as well. In the case of investigating the time dependency of degradation, high-molecular HA was dried at a temperature of 75 °C at a time range from 15 minutes to 120 minutes prior to the preparation of the solutions. During the preparation of the solutions for discovering the temperature dependency of degradation, the high-molecular HA was then dried for a period of 30 minutes at a temperature range from 60 °C to 90 °C. For low-molecular HA, thermal stability was proven. Therefore, there is no decrease in the molecular mass and the solutions did not demonstrate a significant decrease of viscosity. For high-molecular HA, thermal stability was not proven. Degradation due to the temperature of drying as well as the time of drying occurred, which was demonstrated by a significant decrease in molecular mass and viscosity of the solutions. While in the case of using a drying temperature of 60 °C, a decrease in the molecular mass occurred by approximately 5 %, the molecular mass decreased by approximately 20 % at a drying temperature of 90 °C compared to undried HA. Due to this reason, high-molecular HA was also further investigated by means of the TGA method, where the decrease of humidity of HA samples in relation to the drying temperature was observed. The DSC method was also used. The objective of the DSC method was to find out temperatures, at which evaporation of humidity contained in an HA sample in relation to its form (undried HA, dried HA and lyophilized HA) occurs. This method further finds out the heat necessary to evaporate humidity from an HA sample. To conclude this research, the results obtained for high-molecular HA were compared with the results of other drying processes – lyophilized proved to be a very gentle drying method because a decrease in the molecular mass for lyophilized HA compared with undried HA almost did not occur.
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Optimization of the Production of Lipases by Bacillus subtilis
Slavíčková, Radka ; Omelková, Jiřina (referee) ; Hermanová, Soňa (advisor)
In this thesis, optimization of production of lipolytic enzymes by submerzed cultivation of Bacillus subtilis (BS) was studied. Production of lipolytic enzymes was tested in three nutrient media, which differed mainly in main sources of carbon, respectively of nitrogen. The first medium contained mainly extract from calf brain and beef heart (BHIB), the second medium contained peptone and yeast extract (NB) and the third one contained peptone and yeast extract with the addition of 2% (w/v) glucose (NBG). The highest lipolytic activity (0.0784 Uml-1) was measured in NBG medium. Maximum of lipolytic activity was observed before the end of the exponential phase of BS growth in all the media. Temperature optimum in NBG medium was determined from 30 to 50 °C, pH optimum in the range of 5 to 11 and subsequently the temperature stability of lipolytic enzymes produced by the BS was estimated. The activity value was determined spectrometrically using p-nitrophenyllaurate as a substrate. Produced lipolytic enzymes showed maximum activity at 37 °C in the alkaline pH of 8.0. Measurement of temperature stability showed that lipolytic enzymes are relatively thermostable enzymes retaining 100 % of the activity even after 1 hour of cultivation at 30 - 50 °C. The presence of 1% (w/v) olive oil in medium NBG caused a decrease in lipolytic activity by 65 % as well as in pH from 6.5 to 5.4 after 14 days of cultivation. After substitution of glucose by fructose in medium NBG, lipolytic activity showed comparable values during the first week of cultivation. On the other hand, the decrease of lipolytic activity by 29 % in the medium with fructose was observed after 14 days of cultivation. A procedure for the identification of lipolytic enzymes of BS by peptide massfingerprinting was developed to understand the potential of synthetic polyester - poly(e-caprolactone) as a lipase inductor. Degradation study of commercial polyester poly(e-caprolactone) was carried out by submerged cultivation of Bacillus subtilis in NBG medium at initial pH 7.0 and 30 °C for 14 days. PCL (Mn = 10,000, Mw = 14 000) was studied in the form of films (1.0 x 1.0 cm), which were prepared by melt-pressing, rapid cooling of the melt to 4 °C and evaporation of the solvent from 2 % dichlormethane solution. The evaluation of the films shown occurrence of weight loss (7.8 - 17.0 wt.%) together with the formation of numerous holes and cracks in the sample surface in relation to the method of the films preparation. Lipolytic activity values increased by 9 - 17 % in the degradation media compared to control samples. Densitometric monitoring showed also higher increase in cell mass in the degradation medium compared with control samples. Based on the results obtained, the degradation process induced by BS could be suggested.
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