National Repository of Grey Literature 108 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Thermodynamic analysis of solid oxide cells
Vágner, Petr ; Maršík, František (advisor) ; Grmela, Miroslav (referee) ; Pekař, Miloslav (referee)
Thermodynamic analysis of solid oxide cells Petr Vágner The thesis deals with continuum thermodynamic modeling and analysis of phe- nomena in solid oxide electrochemical cells. A general description of the evo- lution of charged mixtures using partial mass densities, momentum density, entropy density, electric induction, magnetic field, polarization, and magnetiza- tion based on the GENERIC framework is formulated. The formulation is used to recover the Landau-Lifshitz magnetization relaxation model, the Single Re- laxation Time model for dielectrics, and the generalized Poisson-Nernst-Planck model. The latter model is consequently linked to the second part, where a novel double layer model of an yttria-stabilized zirconia interface is formulated within non-equilibrium thermodynamics. The model is solved for numerically in the time domain, and cyclic voltammetry of the system is analyzed. The last part of the thesis demonstrates the limits of Exergy Analysis on a simple solid oxide hydrogen fuel cell model with non-isothermal boundary. It is demon- strated that the minimization of entropy production does not necessarily lead to the maximization of the electric power for certain optimization scenarios. The thesis consists of a compilation of published and unpublished results of the author.
Stability evaluation of cosmetic dispersions using centrifugal analyser
Procházková, Michaela ; Krouská, Jitka (referee) ; Pekař, Miloslav (advisor)
This bachelor thesis is focused on the evaluation of stability of cosmetics emulsions prepared from ingredients commonly available in laboratory and compared to the stability of commercially available body lotions. In the theoretical part cosmetics emulsion and methods used to stability measurements were described. Experimental part of this work at first describes the preparation of the emulsions. Furthermore, the stability of prepared emulsion was compared to commercially available ones using the centrifugal analyser LUMiSizer. In conclusion, the test results obtained from analyser LUMiSizer have showed the stability of the commercial emulsions and two prepared samples.
Modelling of particle movement in liquid and hydrogel media
Orság, Miroslav ; Sedláček, Petr (referee) ; Pekař, Miloslav (advisor)
Main goal of this thesis was to became familiar with general mathematical description of particle motion in fluid and hydrogel media in COMSOL software. Simulate a basic Brownian motion of particles with various diameter in media with different density. According to software options, simulate motion in polymer structure or in viscoelastic media. Consider an options of the model for use in microrheology and suggest next process in this field.
Complexes of aminoclay and selected organic compounds
Dušek, Jakub ; Pekař, Miloslav (referee) ; Mravec, Filip (advisor)
This paper describes the preparation of aminoclay and complexes of aminoclay with selected bioactive substances. The theoretical part deals with the study of aminoclay and substances suitable for complexes and suitable modification of preparation these complexes. Experimental part of this paper consists of preparation of aminoclay complexes and verification of their formation. In order to verify the formation of the complex by binding of bioactive compounds to the free amino groups of aminoclay were used methods FT-IR (Fourier transform infrared spectroscopy) and XRD (X-ray diffraction). For selected substances, binding to the aminoclay would improve their properties, which was the main motivation for the research. The resulting complexes could be more effective by replacing existing substances used in the pharmaceutical industry and biomedical applications.
Hydrogel phantoms for ultrasound diagnostics
Cerevatova, Cristina ; Smilek, Jiří (referee) ; Pekař, Miloslav (advisor)
This bachelor thesis deals with properties and preparation of hydrogel phantoms used in ultrasound diagnostics. The main object of this work was to get acquainted with the production and problems of phantom models. The theoretical part of the thesis focuses on phantom characterization, the principle of ultrasound, and phantom manufacturing companies. The practical part focuses on production of phantom models in Dansk Fantom Service, and on own production in the laboratory. Then on these phantoms was studied the speed of ultrasound, attenuation, and other physical changes.
Native hyaluronan as a delivery system for hydrophobic drugs
Černá, Eva ; Mravec, Filip (referee) ; Pekař, Miloslav (advisor)
The aim of this paper is to discover whether it is possible to use the native form of hyaluronic acid as a hydrophobic drug carrier for a targeted distribution in the body. In its structure, hyaluronic acid is a linear high molecular weight biopolysaccharide which is found in most living organisms. Hyaluronan is involved in many physiological processes and therefore is essential for the functionality of the human body. It is in most tissues of the human body, high concentration is in the skin, the vitreous body and is also observed in cancer cells that contain several receptors for hyaluronan. These receptors include CD44 and RHAMM. The interaction of the hyaluronic acid delivery system and the hydrophobic medicinal with these receptors could ensure a free passage for drugs to the affected tissue, where the release of the drug would destroy the affected cells. The drug would directly target the damaged tissue and did not burden the rest of the body like the cytotoxic agents do. In this paper the native form of hyaluronic acid, which we normally find in the human organism, was chosen as the carrier. Its properties do not stand above other carrier systems, but its biocompatibility and biodegradability in the body greatly exceed them. High molecular weight hyaluronic acid was used as a carrier and the hydrophobic dye sudan red G, a substance of similar properties, was used instead of a hydrophobic drug.
Agregation of palmitoyl-modified hyaluronan
Lehocká, Nikola ; Mravec, Filip (referee) ; Pekař, Miloslav (advisor)
This thesis deals with the aggregation behaviour of palmitoylhyaluronan in two degrees of substitution, namely 10 % and 16 %. Using a fluorescence spectroscopy method with pyrene as a fluorescence probe, we found a critical micellar concentration. The results were confirmed by measuring the dynamic light scattering, which also showed an increase in the size of aggre-gates with an increasing concentration. System stability is reduced by increased ionic strength as evidenced by zeta potential measurement. Experiments found that 16 % substitution sample can form a gel. The gel is very stiff and has excellent properties, which was confirmed by rhe-ology. We also managed to incorporate pyrene in the gel, which was demonstrated by the presence of highly solvated domains that could be polymer micelles. Based on these results, 16% substitution sample was subjected the MTT assay to cytotoxicity. The results confirmed that the examined sample was not toxic.
Studying the quality of hydrophobic domains in the phase separated hydrogels
Burešová, Natálie ; Pekař, Miloslav (referee) ; Mravec, Filip (advisor)
The thesis deals with the study of hydrophobic domains in phase separated hydrogels. Two types of polyelectrolytes (hyaluronan, dextran) and oppositely charged surfactants (carbethopendecinium bromide, sodium dodecylsulphate ) are used. Phase separated hydrogels are formed by electrostatic interactions. The target of the thesis is to study the polarity of environment in phase separated hydrogeles by fluorescence spectroscopy. Fluorescence measurements is performed by using pyrene, Nile red and laurdane as fluorescence probes. All probes are sensitive to the polarity of the environment. The results showed that probes can be expected in the polar environment of hydrogels.
Interaction of hyaluronan with surfactant CAE
Trtek, Jan ; Pekař, Miloslav (referee) ; Kargerová, Andrea (advisor)
The diploma thesis is focused on the study of interactions between hyaluronan of various molecular weights with CAE surfactant. This surfactant does not have the exact composition and there is not known their molecular weight. One of the main parameters needed to describe the interactions between surfactant and hyaluronan, there is the determination of critical micellar concentration. The value of critical micellar concentration of CAE is not known yet. All measurements were made for solutions in aqueous solution and 0.15 M NaCl. The determination of the molecular weight of this surfactant was performed by the technique SEC-MALS-dRI. High resolution ultrasonic spectroscopy was chosen to determine the critical micellar concentration and tensiometry was chosen as a complementary method. The interactions of CAE surfactant with polysaccharide of hyaluronan were showed by high resolution ultrasonic spectroscopy and densitometry. Compressibility was calculated from ultrasonic velocity and density.
Time-Resolved Fluorescence in Research of Hyaluronan-Colloidal Systems Interactions
Mondek, Jakub ; Táborský, Petr (referee) ; Peter, Kapusta (referee) ; Pekař, Miloslav (advisor)
The aim of the doctoral thesis was to study advanced fluorescence techniques and its use in colloids or hyaluronan-surfactant systems and hydrogels based on hyaluronan, respectively. Steady-state and time-resolved fluorescence were used to study excited state proton transfer fluroescen probes in hyaluronan-surfactant systems to asses the influence of hyaluronan hydration to its interactions with oppositely charged surfactants. Firstly, different excited state proton transfer fluorescence probes were discussed to choose the most suitable candidate for next research. The influence of hyaluronan on inner environment of micells was determined based on the sensitivity of excited state proton transfer of chosen fluorescence probe 1-naphtol and, based on above mentioned experiments, the structure of hyaluronan hydration shell was discussed. The next part of doctoral thesis was focused on fluorescence lifetime correlation spectroscopy and on the development of method of nanorheology. Measured correlation functions were transformed to mean square displacement with developed MATLAB script. Firstly, the fluorescence method was compared with well described methods such as videomicrorheology and dynamic light scattering to asses the reliability of fluorescence correlation spectroscopy in microrheology. Secondly, nanorheology method was developed and its use in passive nanorheology of hyaluronan hydrogels was discussed. Based on mentioned experiments, the fluorescence correlation spectroscopy microrheology and nanorheology methods were optimized to use the methods in hydrogel research.

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See also: similar author names
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