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Preparation of microfiber structures based on PHB copolymer
Kecíková, Alžbeta ; Brtníková, Jana (referee) ; Přikryl, Radek (advisor)
Master’s thesis deals with the preparation of microfibrous structures based on poly(3-hydroxybutyrate) (P3HB) and its copolymer with poly(4-hydroxybutyrate) using centrifugal spinning technology. The microfibers were modified by the addition of oligomer P3HB and a plasticizer. The centrifugal spinning process was optimized for each material by solution viscosity, polymer molecular weight, speed of spineret, and presence of solvent. One of the part of optimalization was the addition of formic acid and acetic acid to the dissolution system. Microfibrous structures have been investigated in terms of morphology, mechanical properties, wetting and biocompatibility. P3HB fibers were also surface treated with lipase solutions to reduce their hydrophobicity. The prepared bulky fiber cocoons have a suitable 3D microstructure for monitoring and testing biological properties in vitro. Thus, a potential application of microfiber structures is as 3D cell culture carriers in an scaffolds in vitro system.
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Condenser
Juráš, Filip ; Baláš, Marek (referee) ; Pospíšil, Jiří (advisor)
The Master´s thesis is dealing with water-cooled condensers and is splitted into three main parts. The first section provides general knowledge about condensers and heat exchangers, including the basic information of hydrophobic surfaces. These surfaces were used during verifying the impact of hydrophobicity on the heat exchange in water steam. The second section describes an experimental testing. It shows the difference between hydrophobic and nonhydrophobic surfaces and their impact on the heat exchange. The third and the last part of this thesis is design and calculation of water-cooled condenser. The design of the condenser is supported by drawings placed in attachement.
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Label Adhesives with Enhanced Humidity Resistance
Kotrlová, Janka ; Jančovičová, Viera (referee) ; Dzik, Petr (advisor)
The main topic of the thesis was to examine the hydrophobicity of labeling adhesives in the state before drying, it means their resistance against condensated moisture. The problem was solved by measuremensts of contact angle between the drop of water and glue. Measurements of dynamic viscosity and wet tack were also performed for the sake of complex characterization of the glue properties. Comparison of properties among single-component adhesives based on the acrylic copolymers alkalised with various agents was made. The impact of starches and industrial additives on glues was determined by the analysis of primary physical and chemical parameters. The purpose of the measurements was to develop a formula of the glue with enhanced atmospheric moisture resistance, that also would have the required parameters in the equilibrium. Finally, some selected glue samples were practically tested for condensation water resistance. These tests were performed in a climatic chamber with water condensating conditions.
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Surface treatment of biocompatible materials
Kováč, Ján ; Kučera, František (referee) ; Krčma, František (advisor)
This bachelor thesis deals with the study of the influence of plasma discharge on changes in the surface properties of the biomaterial. Surface treatements were performed using three types of plasma discharge: gliding arc, dielectric barrier discharge (DBD) and microwave surface wave discharge. Various gaseous mixtures in plasma discharges and their effect on the surface treatment of the biomaterial were investigated. The selected biomaterial was aliphatic biopolymer polycaprolactone (PCL). It is a suitable surface treatment material, thanks to its biodegradability and easy processability. The PCL supplied by Sigma-Aldrich was in the form of pellets, witch had been converted to foil. The film samples were subsequentely exposed to plasma discharges. To characterize the surface properties of the polymer, surface energy was measured using a sissle drop method, a See System from Advex Instrumnets was used to measure. Based on experimental results, we can confirm that the surface has been modified. However, the plasma discharge modifications have led to hydrophilic and not hydrophobic properties of the biomaterial, with the best results in terms of hydrophilicity being achieved by microwave discharge with surface wave. Due to the negative results of the experiment, bactericidal effects were not investigated.
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Compatibility of piezoelectric semicrystalline polymerand osteoblastic cells
Havlíková, Tereza
For the improvement of tissue regeneration,functional polymer scaffolds that can mimic the extracellularmatrix of human tissue are extremely desirable. Depending on thetissue that the scaffolds are intended to resemble, these scaffoldsmust satisfy highly precise requirements such as non-toxicity orfibrous structure. High piezoelectricity and hydrophilicity alsoproved to have convenient effects. Due to their innate capability tocreate surface charges under mechanical stress, piezoelectricmaterials such as polyvinylidene fluoride (PVDF) become excellentcandidates for creating functional scaffolds. It is desired for PVDFto also have hydrophilic properties. Otherwise, it could preventadequate cell adhesion and growth necessary for the constructionof biomimetic scaffolds. For this study, electrospinned PVDFnanofibers covered by human or mouse osteoblasts were subjectedto Raman spectroscopy, measurement of the contact angle of theliquid wettability on the sample surface to observe hydrophobicityand hydrophilicity, and scanning electron microscopy (SEM) toassess properties of the material in relation to oxygen plasmatreatment.
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Preparation of microfiber structures based on PHB copolymer
Kecíková, Alžbeta ; Brtníková, Jana (referee) ; Přikryl, Radek (advisor)
Master’s thesis deals with the preparation of microfibrous structures based on poly(3-hydroxybutyrate) (P3HB) and its copolymer with poly(4-hydroxybutyrate) using centrifugal spinning technology. The microfibers were modified by the addition of oligomer P3HB and a plasticizer. The centrifugal spinning process was optimized for each material by solution viscosity, polymer molecular weight, speed of spineret, and presence of solvent. One of the part of optimalization was the addition of formic acid and acetic acid to the dissolution system. Microfibrous structures have been investigated in terms of morphology, mechanical properties, wetting and biocompatibility. P3HB fibers were also surface treated with lipase solutions to reduce their hydrophobicity. The prepared bulky fiber cocoons have a suitable 3D microstructure for monitoring and testing biological properties in vitro. Thus, a potential application of microfiber structures is as 3D cell culture carriers in an scaffolds in vitro system.
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Characterization of extracellular and intracellular organic matter produced by phytoplankton in relation to water treatment
Zezulová, Tereza ; Pivokonský, Martin (advisor) ; Janda, Václav (referee)
This study investigated characteristics of algal organic matter (AOM) derived from four species (cyanobacteria Microcystis aeruginosa and Merismopedia tenuissima, diatom Fragilaria crotonensis and green alga Chlamydomonas geitleri) dominating phytoplanktonic populations in the reservoirs supplying drinking water treatment plants - the water reservoirs Švihov (the Želivka water treatment plant) and Josefův Důl (the Jizerské Mountains), Czech Republic. The four mentioned microorganisms were cultivated under laboratory conditions and the algal growth was quantified by a number of cells, chrorophyll-a and optical density. Production of AOM was evaluated by dissolved organic carbon concentration measurements, by specific UV absorbance, the amount of peptide/protein and non-peptide (carbohydrate) contents, water affinity and molecular weight (MW). AOM of all considered microorganisms are formed predominantly by hydrophilic substances with low values of specific UV absorbance (< 2 L/(m.mg)). Considerable portions of both types of AOM, i.e. extracellular and cellular organic matters are represented by substances with MW < 1 kDa or with MW > 100 kDa. However, the total amount and composition of AOM significantly depend on algal species and their growth. The obtained results imply that the knowledge of AOM...
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Depozition of hydrophobic fluorocarbon coatings by plasma polymerization methods
Petr, Martin
In this work we study the deposition of hydrophobic fluorocarbon coatings by magnetron sputtering of polymeric PTFE target. We show what is the influence of the conditions of the deposition process - the pressure in the chamber, the RF power - on the properties of the resulting CFx thin films (their chemical composition, morphology, wettability, barrier and optical properties, stability and possible bio-aplications). In this work we use a novel way to control the morphology and the chemical composition of the surface of thin films independently by using nano-particles, both metal (Pt, Cu, Al) and polymeric (C:H, Nylon). With nano-particles we can control the hydrophobicity of thin films and we can prepare super-hydrophobic films. Work has an experimental character.
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Drop coating deposition Raman spectroscopy of biologically important molecules
Kuižová, Alžbeta ; Kočišová, Eva (advisor) ; Holoubek, Aleš (referee)
Drop coating deposition Raman (DCDR) spectroscopy is a special method of Raman spectroscopy, which is based on the evaporation of solvent from a drop of solution or suspension on a hydrophobic surface. This typically leads to the formation of ring-shaped drying pattern, often called as "coffee ring". As a result a preconcentration of a material and higher intensity of Raman signal in comparison with Raman scattering from solution is obtained. In this work several hydrophobic surfaces with different roughness and hydrophobicity were compared: a smooth substrate with polytetrafluorethylen (pPTFE) coating and nanorough substrates where surface hydrophobicity was formed by deposited cupper or argent nanoparticles with different concentration. It was shown that for DPPC liposome suspension stronger preconcentration is obtained by means of a nanorough substrate. When different nanorough substrate compared, no better improvement was acquired. As for the drying of drops at different temperatures (from 15řC to 60řC) deposited on the smooth pPTFE substrate and the substrate with argent nanoparticles, it was observed that Raman spectra did not reveal any spectral changes corresponding to phase transition of lipid. In case of drying at temperatures higher than a temperature of the phase transition, non-homogeneities...
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Plasma treatment of fabrics
STEHLÍK, Radim
The thesis deals with the surface modification of cotton fabric by low-pressure micro-wave plasma discharge. The main materials used for this experiment are cotton fabrics and hexamethyldisiloxane. The experiment itself is focused on the modification of cotton fabric to improve hydrophobic atributes. An argon process gas was used in the surface modification. The individual treated samples were operated with changes in process gas flow and the time during which the above-mentioned modifications was performed. Two methods were used to analyze the results of the experiment. The first one was aimed at determining changes in hydrophobic atributes in the form of wetta-bility in an unmodified sample compared to other modificated samples using the drop-let method. An electron microscope was used for the subsequent study of possible changes in surface topography. From the point of view of the examined results, the difference in hydrophobic properties was observed when using the droplet method to-gether with the change in the topography of the surface obtained on the electron mi-croscope in the cotton samples examined. The actual evaluation of individual methods points to the desirable changes in modified cotton compared to unmodified cotton. Further information regarding the results of the experiment, depending on the changes in individual parameters in the cotton treatment process using low pressure microwave plasma discharge, are presented in thesis.
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