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High Pressure Viscometer
Skalický, Lukáš ; Hartl, Martin (referee) ; Křupka, Ivan (advisor)
The master´s thesis describes design of falling ball high pressure viscometer for measurements of rheological properties of liquids under high pressure and in the wide temperature range. The design is based on similar apparatuses, which are described in literature. The speed of falling sinker is measured by two optical senzors. Apparatus allows measuring of viscosity, density and optical observing structure of liquid. There was developed extensive program for the evaluation of measurement in Matlab. Apparatus is placed in the laboratory of the Institute of Machine and Industrial Design FME BUT and is used for research and creative activities.
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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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Preparation, characterization and evaluation of application potential of semiIPN hydrogels
Papežíková, Hana ; Pekař, Miloslav (referee) ; Sedláček, Petr (advisor)
Aim of this thesis os to optimize set up of hydrogel based on semi-interpenetrated polymer networks. Polyhydroxyethylmethyl acrylate was chosen as an model example of hydrogel due to its common use in biomedicine. At first, thermoiniciation was used for preparation and changed to photoiniciation afterwards. Following the optimisation of the hydrogel set up with proper qualities, the polyelectrolyte sodium polystyrene sulfonate was implanted. Object of research was its impact on structure, flowing and transport features of hydrogels. All qualities were tested by drying, rheology, and fluorescence correlation spectroscopy. Results clearly validate influence of hydrogel features by polyelectrolytes.
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Development of Material Based on Hyaluronic Acid s Hydrogels for Myocardial Regeneration
Kovářová, Lenka ; Kubala,, Lukáš (referee) ; Prokš,, Vladimír (referee) ; Pekař, Miloslav (advisor)
The thesis is focused on material development based on hyaluronic acid usable in regenerative medicine, especially for heart tissue regeneration after myocardial infarction. The object of the study is the oxidized form of hyaluronic acid (HA-Ox) and hydroxyphenyl derivative of HA (HA-TA). HA-Ox can be crosslinked with a bifunctional alkoxyamine POA and HA-TA undergoes an enzymatic reaction in the presence of hydrogen peroxide catalysed by horseradish peroxidase leading to gel formation. To describe the materials, chemical and physical properties, gelation kinetics and conditions of crosslinking reactions were studied. Hydrogels were characterized by mechanical and viscoelastic properties, degradability or stability in simulated body fluids. These hydrogels serve as scaffolds for the selected cell type. To promote cell adhesion and viability, an RGD sequence has been bonded to the structure of HA-TA. This resulting material is also compatible with selected applicators. Its viscosity and extrusion force are low enough to allow application with a catheter with a very small internal diameter. The applicability of the material through the supply tube to the hydrogel reservoir of the second SPREADS device showed good homogeneity, cell distribution and viability. Finally, the material was applied in vivo using these devices during a preclinical study.
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Preparation of humic hydrogels for appliaction in cosmetics
Pavlicová, Renata ; Mravec, Filip (referee) ; Sedláček, Petr (advisor)
This bachelor´s thesis is focused on the preparation and characterization of hydrogels containing humic substances and assessment of their potential usefulness in cosmetic practice. Main objective of the work was to develop a literature review focusing on the potential use of humic substances in the cosmetics and pharmaceutical industries. Furthermore, the aim was to prepare model hydrogels addition of soluble humic substances in traditional cosmetic compositions and their characterization by basic methods of analysis parameters. The main investigated parameters were consistency resulting gels (assessed subjectively and subsequently by rheology), their internal pH and dry matter. The experimental results showed that incorporation of humic substances into hydrogels resulting gels acceptable characteristics for further use in cosmetic applications.
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Derivatization of Sodium Hyaluronate as a Possible Tool for Increasing of the Stability of Model Artificial Synovial Fluid
Hrochová, Eliška ; Mravec, Filip (referee) ; Kalina, Michal (advisor)
This master thesis deals with the optimization of the procedure of modification of hyaluronic acid structure for the use in the artificial synovial liquids. Based on the literature research, the amino acid alanine was used for the modification of carboxylic group in the glucuronic acid. The main subject of study is the improvement of the stability and mechanical properties of synovial liquid. DLS microrheology, macrorheology, thermogravimetric analysis (TGA), multi-angle light scattering with flow-field flow fractionation (AF4-MALS) and infrared spectroscopy (FTIR) were used for characterization. The theoretical part of this theses submits review of the musculoskeletal system, role of hyaluronic acid in metabolism and summary of synovial liquid. The experimental part focuses on the measurement of the stability and mechanical properties of three artificial samples (first with no modification, second with modified hyaluronic acid and third with modified hyaluronic acid and chondroitin sulphate). These samples were compared with real horse synovial fluid and artificial viscosupplement Orthovisc®.
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Technical viscous curve for injection molding
Hejkalová, Anna ; Svoboda, Jan (referee) ; Kandus, Bohumil (advisor)
Injection molding is highly dependent on flow qualities of plastics. The bachelor thesis compares the conventional measurement of their rheological attributes with the method of injection molding to the technical viscous curve. This method enables to determine the optimum injection rate at which injection resistance does not allow significant improvement of the melt’s flow attributes, on the contrary increases the energy consumption of the process. At the same time, the thesis tries to prove the advantage of this method.
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Study on Sol-gel Process of Agarose by Classical Rheology and Dynamic Light Scattering
Krňávková, Šárka ; Hnyluchová, Zuzana (referee) ; Smilek, Jiří (advisor)
The main aim of the bachelor thesis was characterization of hydrogels from rheological point of view and by dynamic light scattering. Rheological part of research relates with the determination of the influence of temperature on mechanical properties, gelation temperature and temperature of solidification as well as the effect of aging on mechanical properties of hydrogel. The influence of the particle size on diffusion coefficient was investigated by scattering techniques. The positive correlation between the data obtained by both types of measurement and the potencial usage of dynamic light scattering method for the characterization of hydrogels was discussed as well.
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Influence of particle size of cosmetic pigments on final properties product
Obručová, Kateřina ; Hurčíková, Andrea (referee) ; Zemanová, Jana (advisor)
This diploma thesis is focused on the study of the influence of the of size cosmetics pigments on the properties of the final product. This effect was studied on samples of make-up given by industry partner. Make-up samples were measured by the rheology method and the yield stress of all samples was determined. Scanning electron microscopy was used to determine the size and shape of the pigment particles. Particle size was also measured by dynamic light scattering, but the results were influenced by forming aggregates. To easier determination of the types of pigments in the sample was determined elemental composition of the pigments (Ti, Fe, O, Al) by EDS detector. Due to the unknown composition of make-up, the information was supplemented by X-ray powder diffraction (XRD) analysis, and it was possible to determine the compounds TiO2 (anatase and rutile), FeOOH and Fe2O3. The results obtained by these methods showed what pigments can be found in make-up samples, what their sizes and shapes are. It has been shown that the smaller the pigments are, the higher the viscosity and yield stress of the final product. The higher these quantities, the harder it is to handle the product.
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Viscoelastic properties of hydrogels depending on relative humidity
Kouřilová, Ludmila ; Heger, Richard (referee) ; Smilek, Jiří (advisor)
This bachelor thesis is mainly aimed on the determination of the dependence of the viscoelastic properties of physically crosslinked hydrogels on the relative humidity controlled by humidity cell (as an accessory to a rotary rheometer), or the desiccator with the drying medium. The main objective was to optimise the methodology of the humidity cell for the rheological determination of the viscoelastic properties of hydrogel materials as a function of relative humidity and to verify experimental setup on the agarose hydrogel. The results showed that the agarose hydrogel gradually loses its dispersion medium after exposure to chosen relative humidity, resulting in a loss of contact between the upper rheometer sensor and the sample when measured with the standard measurement gap control setting, which is constant during the measurement. The setting of the control of normal force proved to be an appropriate solution, which has led to a gradual reduction in the height of the upper rheometer sensor in an attempt to keep the normal force at the desired level during the drying of the hydrogel. A humidity cell proves to be an appropriate method for determining the dependence of the viscoelastic properties of hydrogels on relative humidity. Unlike the use of a desiccator with drying medium, the drying of the hydrogel sample does not result in such rapid drying that it breaks the texture on its surface. Another advantage of a humidity cell is the ability to maintain the desired relative humidity value even if the gel begins to release dispersion medium into its surroundings, which was not possible with a desiccator with drying medium.
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