Degradace půdy zasolováním, zvyšující se teplota a následný úbytek mnonžství srážek v posledních letech vedou k rozšiřování aridních a semi-aridních oblastí (v současnosti pokrývají třetinu pevniny Země). Navíc představují globální environmentální problémy, které, pokud se nebudou správně řešit, můžou vést k vážné celosvětové krizi. V této diplomové práci jsme propojili tato témata a zaměřili se na lepší porozumění role sodných kationtů na vazbu vody v půdní organické hmotě v aridních a semi-aridních podmínkách. Náš cíl byl prozkoumat proces vzniku a stabilitu vodních molekulových můstků a vodních-kationických můstků v půdní organické hmotě, sílu vazby a množství vázáné vody v půdě za využití diferenční kompenzační kalorimetrie. Nasycení sodnými kationty bylo studováno ve dvou koncentračních oblastech. Na simulaci přirozených podmínek v půdách bylo použito nasycení vazebných míst sodnými kationty do 100% a nasycení nad 100% reprezentovalo vysoce zasolené půdy. Výsledky potvrdily význam schopnosti půdy získávat vodu ze vzdušné vlhkosti, podíl vody v půdě vzrůstal s relativní vlhkostí. Vyšší podíl vody v půdě pak způsoboval snížení síly vazebných interakcí, což bylo interpretováno jako fakt, že rovnováha mezi půdní a vzdušnou vlhkostí vede k optimální vlhkost půdy. Přítomnost sodných kationtů ve vzorcích do nasycení 100% měla na množství vody zanedbatelný vliv, ale v přesycených vzorcích umožňovala navázání většího množství vody. V přesycených vzorcích bylo také pozorováno zvýšení síly vazebných interakcí mezi půdou a vodou, což vede k její větší zádrži. Molekulové můstky byli stabilnější ve vzorcích, které obsahovaly Na+. Nejvyšší stabilita byla pozorována u 10% nasycených vzorcích, další zvyšování Na-saturace pak již vedlo k snižování stability molekulových můstků. Hlavním výstupem práce je, že tvorba vodních-kationických můstků stabilizuje půdní strukturu a že má vlyv na sílu a množství vody vázané v půdě, což představuje klíčové aspekty kvality půdy. Je potřebný rozsáhlejší výskum tohoto tématu, aby získané výsledky pomohli optimalizovat půdní manažment v aridních oblastech a také v ostatních oblastech, kde dochází k degradaci půdy.

Peatlands are considered to be valuable ecosystems on the Planet and play an important role in many processes globally likewise and in the landscape. They are important for maintaining a global biodiversity, play an important role in landscape hydrology and can be a source of drinking water. They can help minimize floods and contribute to climate change mitigation. The peat bogs are one of the largest terrestrial carbon reservoirs. They have been storing carbon for centuries. Many of peat functions are affected due to human activities. It can result into release of greenhouse gases into atmosphere and the excretion of organic carbon into watercourses. The subject of the thesis is understanding of the mechanisms of water binding in peat and exploring possible dependencies within the depth profile of the peatlands using thermal analytical methods, more preciously using thermogravimetry (TG) and differential scanning calorimetry (DSC). The stability of water molecule bridge (WaMB) was investigated. It was found out that the minimum temperature required for WaMB abatement decrease and the whole structure becomes less stable with increasing peat layer depth. Water release processes were evaluated with the meaning of the TGA measurements. A decreasing trend in the degradation of thermolabile substances and an increasing trend in thermostable substances within the peat profile were observed.

Platinum nanoparticles pose a risk to environmental compartments. The aim of this diploma thesis is to conduct research on the influence of platinum nanoparticles in a wide range of concentrations on soil properties at different humidities. Specifically, it is about influencing the stability of water molecular bridges, the content of aliphatic crystallites, the retention capacity of water in the soil and the strength of water binding. Furthermore, the amount of nanoparticles sorbed on the soil was also measured. These indicators give us more information about the influence of platinum nanoparticles on evapotranspiration and soil deterioration. Methods of thermal analysis (differential scanning calorimetry) and optical methods (atomic absorption spectrometry) were used for these researches. The theoretical part of the work is devoted to a comprehensive introduction to platinum and its nanoparticles, as well as aqueous molecular bridges. It has been found that 200 nm platinum nanoparticles affect the strength of aqueous molecular bridges, have no effect on aliphatic crystallite content, have minimal effect on soil water retention, and that the water bond strength decreases due to platinum nanoparticles at high relative humidity. With 200 nm platinum nanoparticles, complete adsorption to soil occurs over the entire concentration range. With 3 nm nanoparticles, the soil is supersaturated at higher concentrations and larger amounts are not adsorbed. The results show that the larger the size of the platinum nanoparticles, the lower the negative effect on evapotranspiration and soil function itself.

Nanoparticles present potential risk for environmental compartments including soil. Previous works have been focused on negative effects of nanoparticles on soil biota, however studies about the influence of nanoparticles on soil properties are still limited. This thesis investigates an impact of 20 nm titanium dioxide nanoparticles on selected water properties in soil organic matter exposed to air with various relative humidity. Indeed, at 43, 70 and 95 % dominate different water types, i.e. water adsorbed on soil organic matter, water in water molecular bridges and phase water, respectively. Differential scanning calorimetry (DSC) was used in the study. An important finding is that nanoparticles reduce the stability of water molecular bridges under 70% relative air humidity and generally reduce evaporation enthalpy of water, which represents the ability of the soil to retain water. In the next part the influence of nanoparticles on total water in soil was observed. Under low relative humidity, rutile and anatase affected soil in different ways due to their various hydrophilicity. Under higher relative humidity this effect disappeared. In the last part, ice melting and water evaporation enthalpies of nanoparticle solutions were measured to confirm the presumed effect of nanoparticles on water. The ice melting enthalpy of the solutions was higher relatively to pure water, while the evaporation enthalpy showed a reverse trend (decrease). This confirmed the effects of nanoparticles both for pure water and soil water.

Supramolecular structure of eight commercial types of iPP, its blends with poly(L-lactide) (PP-PLLA) and copolymers with ethylene-propylene rubber (PP-EPR) together with four types of polyethylene (LDPE, HDPE) was uncovered and observed in this work. The spherulitic structure of iPP and PE homopolymers and PP copolymers was uncovered by etching of six different solutions of mineral acids with KMnO4 and by dissolution in four selected solvents. The latter was found to be ineffective. The structure of PP-PLLA blends was uncovered only after recrystallization (the change of structure by annealing and cooling rate). The uncovered crystalline structure was observed directly by confocal laser scanning microscope (CLSM) and SEM. Crystallinity together with a size distribution of crystallites was determined by DSC. It was proved that spherulitic supramolecular structure was easy to uncover by chemical etching only for molded samples and for fracture surfaces of injected samples. The efficiency of etchants varied but, generally, the samples with high degree of crystallinity were etched earlier. The etchants containing nitric acid and high content of sulphuric acid uncovered fine details of shperulites with respect to mixtures containing orthophosporic acid. It was also observed that not only the etchant (especially with nitric acid) itself but also its vapors were effective. The structure was revealed later but the appearance was plastic (3D) and the structure was very fine. The supramolecular structure of PP-PLLA blends differed with amount of each component. The ethylene-rubber phase came forth with increasing time of etching while PP spherulites disappeared in PP-EPR samples. CLSM was shown to be very good tool for observing supramolecular structure of studied samples with respect to SEM, which was proved to be entirely unsuitable for polyolefines. DSC is recommended to be performe before uncovering supramolecular structure for basic information about proportion of amorphous/crystalline phase and size of crystallites.

This diploma thesis deals with study of crystalline structure of polyhydroxybutyrate (PHB), which contains different types of additives for studying of their nucleation activity and which were prepared by mixing. It is about boronitrid (BN), sacharin, hydroxapatit, plasticizer Tegmer a tree types of talc. Crystal structure was analysed by differential scanning calorimetry and x-ray diffraction, supramolecular structure was observed by optical microscopy (polarized and confocal laser scanning). Nucleating activity was evaluated by isothermal and non-isothermal crystallization made on calorimeter and heated table of optical microscope. There is not influence of additives on crystallographic structure, but additives affects number and size of spherulites including crystal domains defects, which can have impact on final mechanical properties. BN and talcs react as nucleating agents, other additives during low and high cooling speeds (vc) inhibit nucleation and in middle cooling speeds are without effect. Nucleating activity is not evaluated by numerically, because decrease of crystallization temperature together with vc is not linear. Results of direct methods are based on picture analysis, which is great benefit for understanding of crystal behaviour of PHB.

First artificial PHB granules were prepared under the terms of this thesis. The effect of used PHB solvent, ultrasonic bath temperature and time, solvent evaporation temperature and stabilizing agent nature was investigated using dynamic and electrophoretic light scattering. The most proper parameters were demonstrated at samples which were prepared by dissolving of PHB in chloroform, stabilizing with CTAB or lecithin, ultrasonifying at 35 °C followed by chloroform evaporating at 60 °C. Based on ATR-FTIR and Raman spectroscopy results, it was found out that PHB within the artificial granules were in crystalline form. The native PHB granules were isolated from Cupriavidus necator using either lysosyme, deoxyribonuclease and cell disruption by ultrasonification or digestion with alcalase, SDS and EDTA. Granules obtained by both isolation procedures were characterized by ATR-FTIR, Raman spectroscopy, light scattering techniques and DSC. According to the analyses results, the second mentioned procedure turned out to be more effective for obtaining the polymer in amorphous state. Furthermore, the polymer within granules recovered by using this procedure was thermally more stable. Last but not least, the native PHB granules samples were exposed to effect of acetone, lipase and sodium hypochlorite, assuming that polymer crystallinity should be increased by these chemicals in varying degrees. The highest degree of crystallinity was achieved after their treatment with lipase.

<p>U ovom radu prikazani su rezultati ispitivanja termičkih, mehaničkih, električnih i optičkih karakteristika kvazibinarnih halkogenida iz sistema Bi-As2S3. Na osnovu termičkih merenja analizirana je kinetika kristalizacionih i predkristalizacionih procesa i utvrđen je mehanizam dekompozicije za različite sastave dobijenih stakala. Primenom impedansne spektroskopije kvantitativno su ocenjeni doprinosi relaksacionih procesa na pojedinim temperaturama u ukupnoj polaraziciji za stakla sa 5 i 7 at.% Bi. Na osnovu merenja Raman spektroskopije identifikovane su nastale strukturne jedinice i konstatovana pojava nanofazne separacije u staklima sa 1.5 i 3 at.% Bi. Mehanička merenja ispitivanih halkogenida različitog sastava ukazala su na povećanje Vickers-ove tvrdoće sa povećanjem udela primesnih atoma. Na osnovu procenjene vrednosti modula elastičnosti ustanovljeno je da uzorak sa 5 at.% Bi odlikuje najgu&scaron;će atomsko pakovanje. Merenja električnih karakteristika u jednosmernom režimu (DC) pokazala su da je udeo lokalizovanih stanja u ukupnom mehanizmu provođenja značajan samo za manje koncentracije primesnih atoma, a da za veće koncentracije dominantan faktor postaju preskoci između delokalizovanih stanja. Skok u provodljivosti za nekoliko redova veličine kod sastava sa složenijom strukturom protumačen je kao posledica fazne separacije. Rezultati&nbsp; ACmerenja dobijeni za sastav sa 5 at.% Bi ukazali su da je u mernom frekventnom intervalu i dalje dominantan mehanizam termičke aktivacije nosilaca naelektrisanja. Kod sastava sa maksimalnim sadržajem Bi uočena je promena provodljivosti u funkciji frekvencije na svim temperaturama, a dobijeni rezultati su u skladu sa postavkama modela korelisanih preskoka barijere (CHB model).</p> / <p>This paper presents the results of investigation ofthermal, mechanical, electrical and optical propertiesof quasibinar chalcogenides from the system Bi-As2S3.&nbsp;Kinetics analysis of softening and crystallizationprocesses was done on the basis of thermalmeasurements, as well the analysis of decompositionmechanism for different compositions of obtainedglasses. The application of impedance spectroscopy enabled quantitative description of relaxation process contributions at selected temperatures in the overallpolarization for the samples with 5 and 7 at.% Bi.&nbsp;Based on measurements of Raman spectroscopy identification of structural units in the investigated chalcogenides was made, as well as the appearance of&nbsp;nano-scale phase separation in the glasses with 1.5 and 3 at.% Bi. Mechanical measurements pointed to the increase of the Vickers hardness with increase of&nbsp;doping atoms content. &nbsp;Based on the estimated value of the modulus of elasticity it was found that the sample &nbsp;with 5 at.% Bi is characterized by the densest atomic&nbsp;arrangement. Measurements of the electrical properties in dc regime (DC) pointed out that the share of localized states in the whole mechanism of conduction&nbsp;is significant only for the smaller concentrations of doping atoms. For the samples with higher concentrations dominant &nbsp;factor in conductivity are transitions between delocalized states. The jump in conductivity by few orders of magnitude, noticed for&nbsp;the compound with heterogeneous structure was interpreted as a consequence of micro-scale phase&nbsp; separation. Results of&nbsp; ACmeasurements for the&nbsp; composition with 5 at.% Bi showed that the mechanism of thermal activation of charge carriers is&nbsp;still dominant in the measured frequency range. For&nbsp;&nbsp; the composition with the maximum content of Bi changes in conductivity versus frequency were observed at all temperatures, and the results were interpreted in accordance with the model of correlated hopping over the barrier (CHB).</p>

The doctoral thesis is divided into two parts - Thermal analysis in physics education on high school and Material research of Al-Zn-Mg(-Cu-Sc-Zr) alloys. Within the first part, the areas of crystallization and/or melting of selected foods were determined using differential scanning calorimetry. A practical lesson for high school physics has been created and tested. The study text focused mainly on differential scanning calorimetry and its use was made. In the second part of the doctoral thesis, there was analysed thermal evolution of the phase transformation in the Al- Zn-Mg(-Cu) alloys with Sc and Zr addition. The effect of (cold and hot) deformation on the decomposition sequences was studied. The hardening effect after annealing above 300 řC in the Sc and Zr alloys is caused by the precipitation of the secondary Al3Sc,Zr) particles. These particles were observed by transmission electron microscopy after annealing up to 360 řC in all studied AlZnMg(Cu)ScZr alloys. In the AlZnMgCu alloy the partial recrystallization was observed after annealing at 350 řC/10 hours and after annealing at 450 řC/10 hours the grain size was 50-200 m (depending on the treatment of the alloy). The addition of Sc, Zr in the AlZnMgCuScZr stabilizes grains and there is no recrystallization in the AlZnMgCuScZr alloy at temperature...

Eine kalorimetrische Kristallisationsuntersuchung unter dynamischer Abkühlung ist bisher noch nicht erfolgt, auch weil die klassischen DSC-Messsysteme hierfür thermisch zu träge sind und die Einschwingzeiten zu lang sind. Durch die Weiterentwicklung der Prüftechnik, insbesondere auf dem Gebiet der Hochgeschwindigkeitskalorimetrie, erscheint es jedoch erstmals möglich, das dynamische Abkühlverhalten prozessnah nachbilden zu können und die Auswirkung auf die Kristallisation zu untersuchen. Im Rahmen dieser Arbeit wurde daher versucht die dynamische Abkühlung einer Kunststoffschmelze aus PBT kalorimetrisch in Abhängigkeit der Werkzeugtemperatur und der Bauteilgeometrie nachzubilden, jeweils bei Betrachtung verschiedener Bauteiltiefen. Hierfür wurden numerisch nichtlineare Kühlratenverläufe bestimmt, die im Anschluss durch Segmentierung linearisiert und somit in ein FSC-Programm überführt werden konnten. Anhand der resultierenden Wärmestromverläufe konnte gezeigt werden, dass eine Interpretation der kalorimetrischen Erfassung unter dynamischer Abkühlung möglich ist und der Verlauf der Kristallisation in verschiedenen Bauteiltiefen in Abhängigkeit der weiteren Randbedingungen nachvollzogen werden kann. / A calorimetric investigation of the crystallization of thermoplastics under dynamic cooling has not performed yet, also because the classical DSC measuring systems are thermally too slow for this purpose and the corresponding settling times are too long. However, as a result of the further development of testing technology, especially in the field of high-speed calorimetry, it seems possible to simulate the dynamic cooling behavior of real processing and to investigate its effects on crystallization. In this work the dynamic cooling of a polymer melt was simulated calorimetrically depending on the tool temperature and the part geometry, in each case considering the different cooling behavior of different part depths. Therefore, numerically nonlinear cooling rate profiles were determined, which could then be linearized by segmentation and thus converted into a calorimetric program. On the basis of the resulting heat flow characteristics it could be shown that an interpretation of the calorimetric detection under dynamic cooling is possible and the course of the crystallization in different part depths can be reconstructed in dependence on the further boundary conditions.