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Light Scattering Techniques in the Study on Formation of Polyelectrolyte Complexes in the System Biopolymer-Surfactant
Valečková, Vendula ; Smilek, Jiří (referee) ; Kalina, Michal (advisor)
This master thesis is dealing with the use of light scattering techniques in the study on formation of polyelectrolyte complexes in the system biopolymer-surfactant. Sodium hyaluronate was chosen as biopolymer and cetyltrimethylammonium bromide and karbethopendecinium bromide were selected as surfactants. The first precipitation experiments were performed to determine the optimal concentration range of surfactants for subsequent titration measurements performed on Zetasizer Nano ZS and for SEC-MALS analysis. The key parameters obtained from these measurements were the values of critical aggregation concentrations in hyaluronate-surfactant systems. It was found out that the increasing molecular weight of hyaluronan in these systems is causing reduction of obtained values of critical aggregation concentrations. Changes of Z-average particle size, zeta potential, polydispersity index, conformation plot, radius of gyration and molecular weight in the hyaluronan-surfactant system were monitored during experiments.
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Optimisation of Isolation Procedure and Characterization of Amorphous PHB granules
Kratochvíl, Zdeněk ; Obruča, Stanislav (referee) ; Kalina, Michal (advisor)
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.
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Physically-based Cloud Rendering on GPU
Elek, Oskár ; Wilkie, Alexander (advisor) ; Křivánek, Jaroslav (referee)
The rendering of participating media is an interesting and important problem without a simple solution. Yet even among the wide variety of participating media the clouds stand out as an especially difficult case, because of their properties that make their simulation even harder. The work presented in this thesis attempts to provide a solution to this problem, and moreover, to make the proposed method to work in interactive rendering speeds. The main design criteria in designing this method were its physical plausibility and maximal utilization of specific cloud properties which would help to balance the complex nature of clouds. As a result the proposed method builds on the well known photon mapping algorithm, but modifies it in several ways to obtain interactive and temporarily coherent results. This is further helped by designing the method in such a way which allows its implementation on contemporary GPUs, taking advantage of their massively parallel sheer computational power. We implement a prototype of the method in an application that renders a single realistic cloud in interactive framerates, and discuss possible extensions of the proposed technique that would allow its use in various practical industrial applications.
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Preparation and characterization of nanoparticles formed by polymer-surfactant complexes
Dvořák, Filip ; Štěpánek, Miroslav (advisor) ; Netopilík, Miloš (referee)
In this work, copolymers of celulose-g-polystyrene (cel-PS) and celulose-g- poly(methylmetacrylate) (cel-PMMA) were characterized using static and dynamic light scattering, transmission electron microscopy and atomic force microscopy. Preparation of nanoparticles of these hydrophobic copolymers in aqueous solution was further studied, by means of precipitation from dioxane solutions using water with added low-molar-mass surfactants sodium dodecylsulfate (SDS) and dodecyltrimethylammonium bromide (DTMAB). It was shown that the ability of the surfactants to stabilize polymer nanoparticles is driven not only by the hydrophobic effect, but it depends also on specific interactions of the polar group of the surfactant with the surface of the nanoparticles. On the basis of the finding that the efficiency of stabilization of cel-PS copolymers is much higher than in case of linear PS, it can be concluded, that the branched structure of copolymers is favorable for the formation of hydrofobically stabilised polymer-surfactant complexes.
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Monitoring the coefficient of light scattering on aerosol particles at the Kosetice background station
Holubová Šmejkalová, Adéla ; Zíková, Naděžda ; Ždímal, Vladimír ; Holoubek, Ivan
The direct effect of the atmospheric aerosols to radiation balance is the scattering or absorption of light on these particles. While solar radiation on aerosol particles or clouds negatively affects the radiation (resulting in cooling), absorbtion causes increasing of the ambient air temperature. Contribution to the study of the effect of aerosol particles on the climate, a measurement of the coefficient of light scattering is carry out at the Kosetice background station. The Integrating Nefelometer measures at 3-wavelength (RGB) forward and back light scattering. The values of the scattering coefficient at 550 nm (green) are typically high in the cold part of the year, reflecting both increased concentrations of pollutants and stable atmospheric conditions. Daily variability is the smallest in summer (varies between 25 and 18 Mm-1), the most noticeable daily variation is observed in the spring, when stable values 44 Mm-1 drop after noon to 26 Mm-1. The calculation of Ångström's exponent showed that in the summer, the fine fraction dominates in the sampled air.
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Utilzation of physico-chemical analyses in study on microbial stress-response
Slaninová, Eva ; Pekař, Miloslav (referee) ; Sedláček, Petr (advisor)
This diploma thesis deals with the utilization of physico-chemical analysis in study on microbial stress–response. The main content of this work was to propose and optimize techniques and methods which are generally used in different industries. Two bacterial strains, Cupriavidus necator H16 and its mutant strain Cupriavidus necator PHB-4 producing polyhydroxyalkanoates (PHA) under certain conditions, were used as model microorganisms. Initially, microscopic teques such as transmission electron microscopy (TEM), cryo scanning electron microscopy (cryo SEM) and atomic force microscopy (AFM) were proposed and tested for the characteriozation of morphological differences of bacteria. Furthermore, viscoelastic properties of bacteria were determined and compared by the oscillatory tests of the rheology method considering another type of samples. Thermal analysis methods, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) in particular, focused on water transport and behavior of intracellular water influenced by presence of the granules of PHB in bacteria. The last technique, utilized in the study, was dynamic and electrophoretic light dispersion during pH changes for characterization of the surface properties of bacteria such as size, zeta potential and the isoelectric point.
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The Study of Biopolymers Stability Using Light Scattering Techniques
Kratochvíl, Zdeněk ; Sedláček, Petr (referee) ; Kalina, Michal (advisor)
The stability of chosen biopolymers (or simple carbohydrates and amino acids) was in-vestigated using light scattering methods. Samples were prepared by dissolving the sub-stance in deionised water or in diluted acetic acid. Firstly, the effect of increasing concen-tration on zeta potential was observed and the optimal concentration for the next measure-ments was determined. Afterwards, the stability and the molecular weight of used sub-stances were studied during long-time storage in different time intervals. It was found out that chitosan, CMC, hyaluronate and sodium alginate were subjected to degradation whereas increase of the molecular weight and the zeta potential was observed in case of BSA. In the end, the samples were exposed to several different external effects, namely the influence of different temperatures, UV radiation and increasing ionic strength. The results showed that rather higher temperature has a significant impact on biopolymers stability. However, used biopolymers were hardly affected by UV radiation except BSA whose molecular weight increased considerably. Decrease of the zeta potential absolute values and the molecular size usually occurred with increasing ionic strength. The change of molecular weight was not detected.
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Rigorous Simulation of Light Interaction with Cells
Dršata, Martin ; Kalousek, Radek (referee) ; Petráček, Jiří (advisor)
This bachelor thesis focuses on rigorous simulations of light scattering by living cells. The first part is dedicated to brief introduction to the given issues and the basic description of the often used computational methods and models of cell structures. Experimental part deals with light scattering simulations using the finite difference time domain method (FDTD). Models of spherical cell and red blood cell are used in these simulations. The aim of the calculations for the first model is to assess the accuracy of the FDTD method with respect to the analytical method using Mie theory of light scattering.
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Preparation and Characterization of Drug Carrier Systems on the Basis of Magnetic Nanoparticles
Chvátalová, Barbora ; Burdíková, Jana (referee) ; Kalina, Michal (advisor)
This bachelor thesis deals with the study of magnetic nanoparticles, optimizing their preparation and stabilization. The nanoparticles with different ratios of Fe2+ and Fe3+ ions were prepared by coprecipitation by variously concentrated sodium hydroxide. Three samples of particles were selected and were further observed. Their stability in Milli-Q water, buffer, polyvinylalcohol, hyaluronic acid and chitosan was studied in function of time using methods of dynamic and electrophoretic light scattering. By UV-VIS spectrometry it was confirmed that the magnetic nanoparticles were actually prepared. Nanoparticles coated with chitosan and hyaluronic acid were then further characterized using FT-IR, XRD and SEM.
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