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Hydration of biomolecules
Flimel, Karol ; Janeček, Jiří (referee) ; Kučerík, Jiří (advisor)
The aim of this thesis was to apply methods of thermal analysis (differential scanning calorimetry and termogravimetry) to study kinetics of water evaporation from hyaluronan. This approach allowed to determine the changes of desorption energies in the course of evaporation and consequently helped to improve the understanding of the hyaluronan hydration. Thermoanalytical methods in combination with model-free kinetics previously suggested by Ozawa were used to determine kinetic parameters of studied processes. Results confirmed previous knowledge about the content of water located in primary hydration shell of hyaluronan, i.e. concentration range from 0.4 – 0.8 g of water per 1 g of hyaluronan. Further, it was found out that during the evaporation in this concentration range, the hyaluronan gel, stabilized probably by hydrogen bonds, is formed.
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Stability of salts and complexes of humic acids
Nováčková, Kristýna ; Šmejkalová, Daniela (referee) ; Kučerík, Jiří (advisor)
Základem práce je studium vlivu přítomnosti kovů inkorporovaných do struktury huminových látek při tepelné zátěži za přítomnosti vzdušného kyslíku. Pro tyto účely byla použita lignitická huminová kyselina, u které byl nejprve retitračně-vodivostní metodou stanoven počet vazných míst, tj. karboxylových skupin. Smícháním s roztoky sodných a měďnatých iontů byly získány koncové produkty s různými stupni nasycení zjištěných vazných míst. Pro zhodnocení termooxidační stability byla provedena termogravimetrická analýza a diferenční kompenzační kalorimetrie. Výsledky přinášejí nový pohled na reaktivitu huminové kyseliny s kovovými ionty v kapalné fázi, poukazují na možný vznik „porézní“ struktury sodných humátů a jejich schopnost retence vody.
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Study on phase transitions in humic substances
Grebíková, Lucie ; Šmejkalová, Daniela (referee) ; Kučerík, Jiří (advisor)
The work is aimed to examine the potential applications of temperature modulated differential scanning calorimetry in study on phase transitions in humic acids. Experiments will deal with both humic standards and the solid rests after sequential extraction of specific molecular fractions to reveal their role in secondary structure of humic acids.
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Thermal behaviour of organically modified clays
Plevová, Eva ; Vaculíková, Lenka ; Vítámvásová, E. ; Šugárková, Věra ; Martynková, G.S.
The clay minerals were modified by two alkylammonium cations under sorption procedure. T X-ray powder diffraction and FT-IR spectroscopy were used to evaluate the intercalation process of organic cations int the clay structure. The organo - montmorillonites exhibited IR spectra giving evidence about sorption or intercalation of the alkylammonium cations. The enhancement of the basal spacing obtained by X-ray diffraction confirmed the intercalation process of cations into montmorillonite and vermiculite samples. Thermal behaviour of the modified clay minerals was investigated by simultaneous thermogravimetry and differential thermal analysis. The organically modified montmorillonites exhibited the higher values of temperatures related to the total melting. Also the temperatures of exotherm effects connected to recrystallization and transformation increased with the concentration of alkylammonium salts. The temperatures of dehydratation and dehydroxilation decreased with concentration of alkylammonium cations. Vermilulite samples showed generally reducing of their thermal stability.
Fulltext: content.csg -  PDF
Plný tet: UGN-0393204 - PDF
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Nanosized particles of oxides and oxide-hydroxides of Mg, Al, Ti
Šubrt, Jan ; Štengl, Václav ; Svobodová, Monika ; Bezdička, Petr ; Kváča, Zdeněk ; Večerníková, Eva ; Bakardjieva, Snejana
Nanosized particles of oxides and oxide-hydroxides of Mg, Al, Ti and Fe were prepared from organic precursors and by homogeneous precipitation of aqueous solutions. The oxide-hydroxides were dried using the 'Critical point drying' method and were characterized by SEM, TEM, electron diffraction, XRD and also by methods of thermal analysis.
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