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The hydration of hyaluronic acid
Průšová, Alena ; Šimon, Peter (oponent) ; Kučerík, Jiří (vedoucí práce)
Hydration is a crucial factor influencing the secondary structure and consequently the function of molecules present in living systems. Due to mutual affinity of water molecules, they form specific structures which composition and physical properties are affected by the presence of an extraneous molecule. Hyaluronan belongs to the group of biomolecules having large binding and retention capability for water. The aim of this work was to investigate the hydration of different molecular fractions hyaluronan and enumerate the amount of water in individual hydration layers. In the first part, the differential scanning calorimetry was used. In the second part of the work, based on the change in compressibility, the bound water was studied using high resolution ultrasonic spectroscopy.
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Determination of benzo(a)pyrene content in smoked meat products using modern isolation techniques
Suranová, Mária ; Šimon, Peter (oponent) ; Šimko, Peter (vedoucí práce)
In this work a new simplified procedure for isolation and determination of PAH in smoked meat products was developed. This procedure is using ASE as selective extraction technique. Its principle is addition of silicagel activated during 18 hours at 140 °C directly to the extraction cell in ratio 10 g to 1 g of homogenized sample. In the next step the sample is extracted by n-hexane at 100 °C and 10 MPa for three 10 minutes static extraction cycles. The flush volume is 60 % and the purge time 120 sec. During the extraction silicagel adsorb koextracted lipids and thus the obtained extract is suitable for immediate HPLC-FLD analysis. On the contrary, the classical extraction procedures with nonpolar solvent require difficult purification of extract for removal of unwanted lipids. Mostly applied techniques here are GPC and SPE. The new procedure was validated for determination of B[a]P as well as for determination of 4 PAH (B[a]A, CHR, B[b]F, B[a]P) in smoked sausages. It meets all requirements to be set by Regulation (EC) No 333/2007, respective by new Regulation (EC) No 836/2011. After the method validation, the content of 4 PAH was investigated in twelve samples of various smoked sausages manufactured in Slovakia. Two analyzed products showed high PAH levels exceeding maximum legislation limits set for B[a]P as well as for sum of 4 PAH by Regulation (EC) No 835/2011.
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Correlation of Thermoanalytical Data with Primary Properties of Humified Substrata
Kislinger, Jiří ; Šimon, Peter (oponent) ; Tesařová, Marta (oponent) ; Schaumann, Gabriele (oponent) ; Pekař, Miloslav (vedoucí práce)
This doctoral thesis is composed as a thermoanalytical study of humified substrata, i.e. humic substances and soils, obtained from several different sources and of various types in order to cover wide range of primary characteristics. It enquires after linear correlations (using Pearson product-moment correlation coefficient) between thermo-oxidative degradation kinetics (observed by means of thermogravimetric analysis (TGA) and expressed as conversion time assessed by non-isothermal isoconversional method) and standard characteristics, such as amount of aromatic and carboxylic carbon present in humic substances determined by nuclear magnetic resonance (NMR) spectroscopy. The main aim is to shed light on the processes of thermo-oxidative degradation of humified pool of natural organic matter and to search for trends between primary and secondary structure of humic substances. The second goal lies within correlating thermogravimetric weight losses of whole soil samples to their microbiological stability measured in laboratory experiments as soil respiration via carbon dioxide evolution method. The purpose consists in assessment of the interrelationship existence and in disclosing what kind of processes occurring during soil respiration can be easily detected by TGA. Results of the work bring more detailed view on thermal analysis of soils and other humified matter. The major benefit of this work is the presentation of emerging applications of thermal analysis for the characterization of soil organic matter and furthermore the contribution to the development of application of thermal analysis techniques in humus science.
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Hydration of Humic Substances
Bursáková, Petra ; Šimon, Peter (oponent) ; Slovák,, Václav (oponent) ; Klučáková, Martina (vedoucí práce)
This doctoral thesis studies the character of hydration water in water/humic substances system. The goal is to determine both quantitative and qualitative aspects of hydration of humic substances (HS) in solid and liquid phase and to explore the differences in properties of water surrounding humic matter with the assistance of high resolution ultrasonic spectroscopy (HRUS) and methods of thermal analysis such as differential scanning calorimetry (DSC) and thermogravimetry (TGA). The main aim of this work is to contribute to the knowledge about hydration of humic samples originating from different sources and thus having different properties and composition applying the approaches and techniques already used and reported as being successful for determination and enumeration of hydration water in hydrophilic biopolymers and hydrogels. This thesis investigates the effect of water on humic structure, its way of wetting and penetrating the surface of HS, the possible conformational changes, the retention capacity of HS, and also the influence of origin of individual humic substance on hydration properties with regard to the kinetic of those processes. Moreover, it tries to recognize the influence of degree of humification on hydration processes of humic substances as well as reversibility of these processes. The results of this thesis reveal same parallelism with the properties of non-reversible hydrogels; some similarities between biopolymers and HS were discovered as well.
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The antioxidant effect of humic acids
Bakajová, Barbora ; Šimon, Peter (oponent) ; Kučerík, Jiří (vedoucí práce)
The main aim of the thesis was to study influence of humic acids and its salts on the thermo-oxidative stability and degradability of polyvinyl alcohol (PVA). For this purpose, thermogravimetry was employed. It has been demonstrated that small concentrations of humic acids caused an increase in stability of investigated PVA. In contrast, high concentrations showed only a slight stabilizing effect, in some cases the presence of humic acids lead even to the PVA destabilization. In the second part, the durability of polymer material was adjusted by the g-irradiation pretreatment. Obtained results indicated that presence of ammonium and sodium salts of humic acids caused a significant stabilization of the polymer material in comparison with the pure PVA and showed the stabilizing effect even after a long term g-irradiation exposition. The last task was to evaluate the ageing effect on the PVA/humic blends. It has been showed that no additional chemical reactions occurred in PVA/humic acids blends and thus the prepared material showed the constant physical properties during the several-months experiments.
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Hydration of Humic Substances
Bursáková, Petra ; Šimon, Peter (oponent) ; Slovák,, Václav (oponent) ; Klučáková, Martina (vedoucí práce)
This doctoral thesis studies the character of hydration water in water/humic substances system. The goal is to determine both quantitative and qualitative aspects of hydration of humic substances (HS) in solid and liquid phase and to explore the differences in properties of water surrounding humic matter with the assistance of high resolution ultrasonic spectroscopy (HRUS) and methods of thermal analysis such as differential scanning calorimetry (DSC) and thermogravimetry (TGA). The main aim of this work is to contribute to the knowledge about hydration of humic samples originating from different sources and thus having different properties and composition applying the approaches and techniques already used and reported as being successful for determination and enumeration of hydration water in hydrophilic biopolymers and hydrogels. This thesis investigates the effect of water on humic structure, its way of wetting and penetrating the surface of HS, the possible conformational changes, the retention capacity of HS, and also the influence of origin of individual humic substance on hydration properties with regard to the kinetic of those processes. Moreover, it tries to recognize the influence of degree of humification on hydration processes of humic substances as well as reversibility of these processes. The results of this thesis reveal same parallelism with the properties of non-reversible hydrogels; some similarities between biopolymers and HS were discovered as well.
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Correlation of Thermoanalytical Data with Primary Properties of Humified Substrata
Kislinger, Jiří ; Šimon, Peter (oponent) ; Tesařová, Marta (oponent) ; Schaumann, Gabriele (oponent) ; Pekař, Miloslav (vedoucí práce)
This doctoral thesis is composed as a thermoanalytical study of humified substrata, i.e. humic substances and soils, obtained from several different sources and of various types in order to cover wide range of primary characteristics. It enquires after linear correlations (using Pearson product-moment correlation coefficient) between thermo-oxidative degradation kinetics (observed by means of thermogravimetric analysis (TGA) and expressed as conversion time assessed by non-isothermal isoconversional method) and standard characteristics, such as amount of aromatic and carboxylic carbon present in humic substances determined by nuclear magnetic resonance (NMR) spectroscopy. The main aim is to shed light on the processes of thermo-oxidative degradation of humified pool of natural organic matter and to search for trends between primary and secondary structure of humic substances. The second goal lies within correlating thermogravimetric weight losses of whole soil samples to their microbiological stability measured in laboratory experiments as soil respiration via carbon dioxide evolution method. The purpose consists in assessment of the interrelationship existence and in disclosing what kind of processes occurring during soil respiration can be easily detected by TGA. Results of the work bring more detailed view on thermal analysis of soils and other humified matter. The major benefit of this work is the presentation of emerging applications of thermal analysis for the characterization of soil organic matter and furthermore the contribution to the development of application of thermal analysis techniques in humus science.
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Study of Hydrophobic Domains in Humic Acids
Čechlovská, Hana ; Šimon, Peter (oponent) ; Franců, Juraj (oponent) ; Pekař, Miloslav (vedoucí práce)
The nature of hydrophobic domains in humic acids was studied from different points of view. To shed light on the meaning of fluorescent spectra, the measured samples underwent the sequential extraction which partially revealed the role of water-soluble components, free and bond lipids in optical properties of humic acids. The results indicated that the fluorescence peaks traditionally attributed to the superposition of individual chemical structures are rather a result of aggregation properties of humic molecules and hydrophobic effect driving aromatic molecules together forming aggregates apparently large molecular weight. Further, it seems that there is a significant influence of non-fluorophores and non-chromophores on the optical properties of humic acids. Results are consistent with the theory on supramolecular structure of humic acids. Next, the aggregation, conformational behaviour and thermodynamic stability of humic acids were studied by high resolution ultrasonic spectroscopy. It was demonstrated that humic molecules are able to interact and form aggregates at very low concentration (
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Determination of benzo(a)pyrene content in smoked meat products using modern isolation techniques
Suranová, Mária ; Šimon, Peter (oponent) ; Šimko, Peter (vedoucí práce)
In this work a new simplified procedure for isolation and determination of PAH in smoked meat products was developed. This procedure is using ASE as selective extraction technique. Its principle is addition of silicagel activated during 18 hours at 140 °C directly to the extraction cell in ratio 10 g to 1 g of homogenized sample. In the next step the sample is extracted by n-hexane at 100 °C and 10 MPa for three 10 minutes static extraction cycles. The flush volume is 60 % and the purge time 120 sec. During the extraction silicagel adsorb koextracted lipids and thus the obtained extract is suitable for immediate HPLC-FLD analysis. On the contrary, the classical extraction procedures with nonpolar solvent require difficult purification of extract for removal of unwanted lipids. Mostly applied techniques here are GPC and SPE. The new procedure was validated for determination of B[a]P as well as for determination of 4 PAH (B[a]A, CHR, B[b]F, B[a]P) in smoked sausages. It meets all requirements to be set by Regulation (EC) No 333/2007, respective by new Regulation (EC) No 836/2011. After the method validation, the content of 4 PAH was investigated in twelve samples of various smoked sausages manufactured in Slovakia. Two analyzed products showed high PAH levels exceeding maximum legislation limits set for B[a]P as well as for sum of 4 PAH by Regulation (EC) No 835/2011.
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The antioxidant effect of humic acids
Bakajová, Barbora ; Šimon, Peter (oponent) ; Kučerík, Jiří (vedoucí práce)
The main aim of the thesis was to study influence of humic acids and its salts on the thermo-oxidative stability and degradability of polyvinyl alcohol (PVA). For this purpose, thermogravimetry was employed. It has been demonstrated that small concentrations of humic acids caused an increase in stability of investigated PVA. In contrast, high concentrations showed only a slight stabilizing effect, in some cases the presence of humic acids lead even to the PVA destabilization. In the second part, the durability of polymer material was adjusted by the g-irradiation pretreatment. Obtained results indicated that presence of ammonium and sodium salts of humic acids caused a significant stabilization of the polymer material in comparison with the pure PVA and showed the stabilizing effect even after a long term g-irradiation exposition. The last task was to evaluate the ageing effect on the PVA/humic blends. It has been showed that no additional chemical reactions occurred in PVA/humic acids blends and thus the prepared material showed the constant physical properties during the several-months experiments.
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