National Repository of Grey Literature 122 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Carbon nanoparticles from South Moravian lignite
Drozdová, Miroslava ; Enev, Vojtěch (referee) ; Pekař, Miloslav (advisor)
This bachelor thesis deals with the issue of isolation of carbon nanoparticles from lignite, which seems to be their cheap source. The aim of this work is to elaborate a research on the use of coal matrices as a source of carbon nanoparticles and also to design and perform further experiments testing the usability of South Moravian lignite. Based on the literature search, a simple mechanochemical procedure was proposed to obtain carbon nanoparticles from lignite. The lignite was mechanically stressed by the ultrasonic disintegrator with simultaneous action of water or hydrogen peroxide. Lignite has been able to isolate particles fluorescing in the blue visible light, but the process will need to be further modified. However, South Moravian lignite could be a source of carbon nanoparticles.
Hydration of biocolloids - calorimetric study
Šméralová, Ester ; Pekař, Miloslav (referee) ; Klučáková, Martina (advisor)
Presented master's thesis focuses on the study of hydration of selected biocolloid substances, specifically humic substances (humic acids and fulvic acids), hyaluronic acid with three different molecular weight, chitosan and dextran. Interaction of biocolloids with water was studied by different methods. The effect of solubility, structure, functional groups in molecule on sorption and hydration ability of these biocolloids was investigated. In the case of hyaluronan the influence of molecular weight was also study. Differential scanning calorimetry DSC and perfusion calorimetry give results of heat of hydration, enthalpies and temperature of crystallization and melting. Thermogravimetric analysis TGA was used to determine the original moisture content of the samples.
PREPARATION AND APPLICATION OF SOME BIOPOLYMERS, NANOPARTICLES AND NANOFIBRES FOR COSMETICS AND FOOD
Bokrová, Jitka ; Pekař, Miloslav (referee) ; Kráčmar, Stanislav (referee) ; Márová, Ivana (advisor)
The presented doctoral thesis is focused on preparation of nanoparticles and nanofibers with natural active ingredient and testing their biological effects. Modern types of application forms were prepared from biomaterials based on one or more natural polymers. Chitosan particles were prepared from cross-linked polymer using ultrasonication. A mixture of soy lecithin and cholesterol was used for preparation of liposomes. Poly-3-hydroxybutyrate was used for preparation of combined liposomes, too. All liposome particles were prepared by ultrasonication. Nanofibers were obtained from polyhydroxybutyrate using electrospinning. Mixtures of low-molecular antioxidants obtained by extraction from natural sources were used as active ingredients. Different types of teas, barks, herbs, spices, fruits and vegetables were selected as sources of natural antioxidants. Total phenolic and flavonoid content and total antioxidant activity of extracts were determined using spectrophotometrical methods. Obtained natural extracts were subsequently used for encapsulation. Prepared application forms were characterized in terms of their physicochemical properties. Particle size was monitored by dynamic light scattering. Colloidal stability of particles in suspension was determined using zeta potential. Spectrophotometry was used to evaluate the efficiency of encapsulation of active compounds into particles. The morphology of the new type of combined PHB liposomes was monitored by electron microscopy. Chromatography was used for quantification of individual components of particles. Morphology of nanofibers and incorporation of active agent into their structure were monitored using FTIR-ATR spectroscopy and electron microscopy. Afterwards, antimicrobial, cytotoxic and genotoxic effects of preparations were evaluated. It was found that the most suitable types of extracts for liposome preparation are aqueous and lipid extracts of natural antioxidants. Prepared particles showed excellent stability and good encapsulation efficiency. The study confirmed that incorporation of polydroxybutyrate into liposome structure does not reduce neither the colloidal stability of the particle, nor the efficiency of encapsulation process. Antimicrobial and antimycotic effect of preparations against model microorganisms Micrococcus lutues, Serratia marcescens and Candida glabrata was detected. It was found that process of encapsulation increases the inhibitory effect of natural extracts of antioxidants. The safety of preparations was assessed using two human cell cultures: epidermal keratinocytes and HaCaT cell line. Assays of cell viability and plasma membrane integrity were used to determine cytotoxicity of preparations. Low toxicity of liposome particles was confirmed by a series of cytotoxic tests. Obtained data showed that association of phospholipid with PHB polymer does not cause a significant increase in cytotoxicity in human skin cells. Genotoxicity testing on model procaryotic organism confirmed zero genotoxic potential of preparations. The new type of combined particles and polymeric fibers cant thus be used as a carrier for active ingredients, complex natural extracts, antimicrobial agents and many others.
Advanced Fluorescence Techniques in Research on Micellar Systems and Their Interactions with Biopolymers
Holínková, Petra ; Burgert, Ladislav (referee) ; Táborský, Petr (referee) ; Pekař, Miloslav (advisor)
The dissertation thesis deals with study of advanced steady-state and time-resolved fluorescence techniques, which can be used for study of micellar systems properties. Selected fluorescence techniques were used for characterization of Septonex and CTAB cationic micellar systems and theirs interactions with hyaluronan. Fluorescent probe pyrene was used for determination of critical micelle concentration (CMC) and micellar aggregation number of these surfactants. The changes of fluorescence behaviour of fluorescein and prodan were studied in wide concentration range of Septonex. Next chapter of thesis deals with study of Förster resonance energy transfer between perylene and fluorescein in Septonex and CTAB micellar solutions and the effect of hyaluronan addition to these systems. Also steady-state and time-resolved fluorescence anisotropy studies were used for research of the effect of hyaluronan addition to micellar solutions. The last chapter of this thesis is focused on photophysical behaviour of Prodan in different solutions (water, Septonex solutions below CMC, hyaluronan solution, Septonex micellar solution and Septonex micellar solution with hyaluronan), which was discussed on the basis of time-resolved emission spectra.
Effects of hyaluronan on properties of eye drops
Chromá, Kateřina ; Mravec, Filip (referee) ; Pekař, Miloslav (advisor)
Modifying eye drops using hyaluronan leads to an increased retention time on the eye surface. Long-lasting observations of the stability of two different eye drops, Opthalmo-Septonex and Visine Classic, after the addition of hyaluronan with varying concentration are presented in this work. The interactions of hyaluronan with the eye drops, or their components benzalkonium chloride and tetryzoline, are investigated by monitoring particle sizes and the charge of the molecules. Additionally, rheological examinations of the samples are done and the mucoadhesion index is determined by using the mucine method.
Preparation and characterization of complex liposomal for drug delivery systems
Szabová, Jana ; Pekař, Miloslav (referee) ; Mravec, Filip (advisor)
This diploma thesis deals with the preparation and characterization of stealth liposomes and their combination with trimethylchitosan (TMC). This complex could find application in the field of inhalation administration. Stealth liposomes were prepared from neutral phophatidylcholine, negatively charged fosfatidic acid and polyethyleneglycol bounded to phosphatidylethanolamine. We have managed to prepare stealth liposomes with suitable properties that should guarantee passive targeting without evocation an immune response, despite the content of the negative component. We also found a suitable method of preparation for stealth liposome–TMC complex, where the change of size and zeta potential confirmed the non–covalent bound between two components despite the content of the polyethyleneglycol.
Hyaluronan hydrogels
Vaculíková, Hana ; Pekař, Miloslav (referee) ; Hurčíková, Andrea (advisor)
In this thesis there was preparation optimized for agarose-gelatin hydrogels with addition of various concentrations of low-molecular and high-molecular hyaluronan and than there were examined viscoelastic properties of them by rheological oscilation tests and high-resolution ultrasonic spektrometry. By rheology were measured values of elastic and viscous modulus for selected amplitude of strain, oscilation frequencies and temperatures. In the second method there were recorded values of ultrasonic velocities of samples at temperature scanning from 85 to 25 °C and from 25 to 85 °C in HR-US 102, which were compared with ultrasonic velocities measured at the temperature 27,0±0,5 °C by gel-modul HR-EX-SSC.
The characterisation of surfactant CAE
Obršlíková, Monika ; Pekař, Miloslav (referee) ; Hurčíková, Andrea (advisor)
CAE is a cationic surfactant derived from DL-Pyrrolidone Carboxylate, L-Arginine and a fatty acid. This surfactant is mainly used in the cosmetic industry. The exact value of critical micellar concentration of CAE is not known yet. In this research there were examined ultrasonic velocity, density, surface tension and scattered light intensity of CAE solutions in ultra-pure deionized water, in 10mM NaCl, 100mM NaCl and 150mM NaCl.
Hydrogels amino-dextran-surfactant: phase diagram
Daňková, Kristýna ; Hurčíková, Andrea (referee) ; Pekař, Miloslav (advisor)
This bachelor thesis deals with a study about hydrogel systems based on the physical interactions of the oppositely charged particles, specifically interactions between positive polyelectrolyte and negative detergent. The phase diagrams were created based on the visual evaluation of results of the laboratory experiment, which is a part of this thesis, for in advance chosen concentration of the polymer diethylaminoethyl-dextran hydrochloride and detergents sodium dodecyl sulphate and sodium tetradecyl sulphate. These phase diagrams characterize incurred dextran systems.
Hydrogels hyaluronan-surfactant: phase diagram
Gruberová, Eliška ; Hurčíková, Andrea (referee) ; Pekař, Miloslav (advisor)
This bachelor’s thesis deals with phase separation of the hyaluronan-cationic surfactant system in a model physiological solution of 0,15 M NaCl resulting in gel formation. The most widely used concentrations of hyaluronan and a wide range of surfactant concentrations was used to form the gel. We have investigated under which conditions the greatest amount of compacted gel was produced. It has been found that phase separation occurs over the entire concentration range. The largest amount of gel was formed at the highest concentration of both hyaluronan and surfactant. The results were plotted in well-arranged graphs. A hydrophobic colorant was used to indicate the presence of micellar formations and the results were depicted in a schematic phase diagram.

National Repository of Grey Literature : 122 records found   1 - 10nextend  jump to record:
See also: similar author names
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7 Pekař, Martin
7 Pekár, Martin
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