National Repository of Grey Literature 58 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Study on adhesion properties of hydrogels to solid surfaces
Šindelářová, Anna ; Sedláček, Petr (referee) ; Smilek, Jiří (advisor)
This bachelors thesis deals with optimization and subsequent verification of the applicability of an unconventional method for determination of adhesion properties of hydrogels and materials related to them, which will then be useful for measuring the adhesion of hydrogels to solid surfaces using rheological techniques. In the case of the presented thesis, the determination of adhesion properties by means of rheometer and simple experiments such as slipping of measured materials on inclined surface is chosen. The results of both of these methods are compared to each other and also to the knowledge gained from literature. The applicability of the methods is assessed in terms of objective results, reproducibility, and whether the measured data are quantitative expressions of adhesion properties. It has been found that rheometry is useful as a reliable quantitative method of measuring adhesion. The rheometric data was reproducible and consistent. By this method, it was found that, with increasing concentration of dispersion, the adhesion force increases, which is in agreement with the knowledge obtained from literature.
Study on the Reactivity of Extracellular Polysaccharides Produced by Bacteria
Vacková, Barbora ; Smilek, Jiří (referee) ; Kalina, Michal (advisor)
This bachelor thesis deals with the reactivity of bacterial extracellular polysaccharides. The experimental part deals with extracellular polysaccharide FucoPol. Due to the presence of acyl groups, the polymer has an anionic character and can promote interactions with other positively charged substances. In this bachelor thesis interactions of FucoPol with metals were studied. For measuring, an isothermal titration calorimeter was used, and sorption experiments were performed. The main objective of the work was optimization of conditions for measuring interactions between metals and FucoPol. Connection of metal cations to FucoPol matrix were confirmed by titration calorimetry and sorption experiments. The interaction rate was different depending on the metal which was used. Co2+, Pb2+ a Zn2+ ions showed very weak binding, otherwise Cu2+ a Fe3+ ions had high affinity for the studied biopolymer. FucoPol, as a biodegradable biopolymer, can be in the future one of important industrially produced polysaccharides. It could be used for packaging, biofuel production and production of anti-inflammatory and immune-boosting drugs.
Interfacial rheology as the effective tool to description of interfacial behaviour of biofilms
Kachlířová, Helena ; Kráčalík, Milan (referee) ; Smilek, Jiří (advisor)
The aim of this diploma thesis is to optimize a method of interfacial rheology for testing the interfacial behaviour of biofilms on the liquid-air interface and after that use the method for studying the biofilm formation under optimal and stress conditions. For studying the biofilm formation, Kombucha was used. It is a microbial culture forming a cellulose biofilm on the interface. As the stress conditions, reduction of sucrose concentration, change of pH and change of ionic strength was used. Next, the ability of regeneration of biofilm formed on the interface was studied. The biofilm formation was occured in all cases except of increasing ionic strength. As expected, the best biofilm biofilm growth was observed under optimal condition, which means a sucrose concentration 100 g/l.
Study on transport of liquid lignohumates through plant leaves and plant cuticles
Rampáčková, Eliška ; Weidlich, Tomáš (referee) ; Smilek, Jiří (advisor)
This thesis deals with the study of transport commercial solution of pottasium lignohumate through the plant cuticles, as the main barriers in transport of active ingredience to plant tissues. The problematics has been studied to obtain the informations about ability of transport liquid active ingredience during foliar fertilization, which became popular in theme of efective utilization fertilizers and reduction their negative impact to enviroment. The aim of this thesis was to optimize technics of diffusion for demanded purposes in the Stokes diffusion cells. As the transport barriers have been used the plant cuticles, that have been isolated by various methods. The ultraviolet and visible spectrometry (UV-VIS) was the analytical method for determination of transported volume of lignohumate and to the mentioned experiments the cuticles of Prunus laurocerasus and cuticles of tomato fruit have been used. The isolated cuticles have been analyzed by optical microscopy, scanning electron microscopy and profilometry. The characterisation of the used solution of lignohumate was also important part of this thesis. It has been used the basic physico-chemical methods and also the advanced methods as tensiometry, size exclusion chromatography with UV detector and differential refractive index detector (SEC-UV-dRI) and thermogravimetry (TGA).
Development of cosmetic cream fulfilling standards of CPK certification
Zinkovska, Natalia ; Kargerová, Andrea (referee) ; Smilek, Jiří (advisor)
The aim of this diploma thesis is to propose a recipe of natural BB-creams with the desired properties (different color shades, that will be suitable for Central European skin type; flow properties, texture, spreadability, stability). The experimental part of the thesis is mainly focused on the development of BB-cream formulas. Several different formulations with diverse dispersion medium (water and aloe vera/water in a suitable ratio) have been proposed, and three different shades of BB-cream have been developed. The flow properties (viscosity) of the samples were measured, accelerated stability tests were realized by using the dispersion analyzer LUMISizer, the obtained results were correlated with the results of stress temperature tests. The results of the rheological analysis showed that the flow properties of the creams are comparable with commercially available preparations. Stress temperature tests have shown that prepared samples remain stable over 4 cycles (12 weeks) of changing storage temperature, accelerated destabilization tests performed by LUMISizer confirmed their stability. The colour coordinates of the developed shades were measured using a spectrophotometer and compared with commercial analogues. Also the questionnaire for sensory evaluation of preparations for more comprehensive analysis of prepared BB-creams was developed. The 25 female respondents of different ages participated in servey. The results of sensory evaluation showed that textural properties of developed creams are satisfactory for potential consumers.
Preparation and characterization of hybrid hydrogels matrix
Magera, Lukáš ; Kalina, Michal (referee) ; Smilek, Jiří (advisor)
Submitted bachelor’s thesis aims for preparation and subsequent optimisation of hybrid hydrogels, which represent material with high application potential because of their unique properties. Hybrid hydrogels have extraordinary mechanical resistance and other beneficial properties (e.g. transportation) due to their unique hybrid network structure, strong interpenetrating network entanglement and efficient energy dissipation system. This work engages in chemically-physically crosslinked hybrid gel, namely the combination of alginate-polyacrylamide. The hybrid hydrogel was formed and then underwent the tests of drying and swelling. The main purpose of the experimental part was to determine viscoelastic properties of hybrid hydrogels using standard oscillation tests. Swelling tests showed that the hybrid network containing limitedly swelling alginate gel reaches lower degree of swelling than the single unlimitedly swelling polyacrylamide gel. Viscoelastic tests unveiled an influence on the mechanical properties by value augmentation of the hybrid gel´s storage modulus in comparison with the reference alginate hydrogel. Hybrid hydrogel reported an increase in the linear viscoelastic area compared to the reference polyacrylamide gel, whose hybrid structure prevents from creating microcracks, that caused earlier rupture of the reference polyacrylamide gel.
Study on flow and viscoelastic properties of laboratory prepared synovial fluids by macrorheological techniques
Veldamonová, Aneta ; Heger, Richard (referee) ; Smilek, Jiří (advisor)
This bachelor thesis deals with preparation and characterization of synthetic synovial fluid. Preparation was focused mostly on finding proper ratios of substances existing in real synovial fluid which have influence on viscoelastic properties. Based on study of literature, these substances are hyaluronic acid, lubricin, phospholipids and proteins. Samples of real synovial fluid from horse hock acquired from University of veterinary and pharmaceutical sciences Brno were tested for comparation with synthetically prepared synovial fluid. Both synthetic and real synovial fluid were characterized by macrorheological techniques. The experimentally obtained data were then compared with data from the patent on which the preparation of synthetic synovial fluid was based on. Thermogravimetry and isothermal thermogravimetry were used as additional method for the study of moisture and water binding of synovial fluids.
Preparation, characterization of trimethylchitosan and verification of its interaction ability with regards to variable charged ionic compounds
Bayerová, Zuzana ; Pekař, Miloslav (referee) ; Smilek, Jiří (advisor)
The aim of this thesis is to study the interactions of trimethylchitosan with oppositely charged substances with regard to its potential biomedical use. A substantial step before the study of interactions was a successful synthesis of trimethylchitosan, which was subsequently confirmed by characterization of the final synthesis product using physico-chemical methods (infrared spectroscopy, elemental analysis, nuclear magnetic resonance). The result product was subjected to negatively charged interactions such as sodium dodecyl sulphate as a representative of the ionic surfactant, alginate as a natural polysaccharide representative and Chicago Blue as a representative of the anionic dye. The ability to interact with sodium dodecyl sulfate and alginate was demonstrated by the formation of hydrogels, which were subsequently characterized by mechanical viscosity tests using rheometric properties. The positive affinity of trimethylchitosan for organic dyes has been investigated in agarose-based support hydrogel matrices for changes in transport and barrier properties.
Study on interaction of humic substances with surface active agents
Bělušová, Anna ; Krouská, Jitka (referee) ; Smilek, Jiří (advisor)
This bachelor thesis deals with the study of interactions between humic acids (HK), as the main component of soil organic matter, and model pollutants in the form of surfactants through unconventional and original combination of dialysis and diffusion techniques. Since dialysis techniques are rarely used for the interaction of humic substances with surfactants study, it was necessary to optimize methods for determining of ionic surfactants (cationic Septonex and anionic sodium dodecylsulfate were selected as representatives) prior to begining of own experiments, using a method based on the color ion pair creation between a surfactant and a counter-charged dye, followed by this pair extraction into an organic solvent. Diffusion cell dialysis experiments were performed with cationic surfactant Septonex, which was expected to interact positively with humic acids relative to its charge. As humic acids representatives, the standards of these substances provided by the International Society for Humic Substances (IHSS) were selected, namely humic acids (IHSS HK) isolated from Leonardite (1S104H). One of this bachelor thesis aims was to verify the effect of carboxylic functional acids on reactivity and barrier abilities of humic acids. For this reason, these standards have been modified by the selective methylation of carboxyl groups which no longer participate in the interaction with surfactants. Already from the first experiments there was a noticeable decrease in the concentration of Septonex over time – it means its transition through the dialysis membrane to humic acids, which indicates a positive affinity of humic acids to Septonex. The extent of these interactions was assessed through the apparent interactions parameter app through which the assumption that IHSS HK reacted with Septonex more than their methylated form of MIHSS HK was verified.
Influence of molecular weight of polymers on phase-separated hydrogels
Kolomá, Nikola ; Smilek, Jiří (referee) ; Mravec, Filip (advisor)
This work is focused on study of individual systems of hyaluronan mixtures. All mixtures of hyaluronans they were ready at molecular weights of 15-30 kDa, 80-150 kDa, or 1500-1750 kDa. These individual molecular weights were combined in different ratios most often in ratios of 70:30, 50:50 and 30:70. Septonex surfactant was used for all mixed samples and CTAB was used for last experiment too. At first the gel samples were prepared by a dry route of individual powders with accurately calculated batches. All solutions were prepared wet route with stock of exactly calculated concentration. Physical gels were prepared by combinations of Septonex and hyaluronan with the different molecular weights. In solution formed irregular shapes which we could describe as "marbles" or "beads". After the sample was to stand, the individual „marbles“ of the gel were formed whole mass. Was done too many experiments with physical gels, which has been carried out behavior of mixtures hyaluronans with different molecular weights. All physical and chemical properties were observed by the eye, described and in the and were photographed. Was used hydrophil dye in experiments and served for better visualize comparison samples between themselves. The last experiment was rheological measurement with which is possible characterize viscosity od individual samples.

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