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Production of extracellular polysaccharides by extremophilic prokaryotes
Bystrická, Klaudia ; Smilek, Jiří (referee) ; Obruča, Stanislav (advisor)
Predložená diplomová práca sa zaoberá štúdiom biotechnologickej produkcie extracelulárnych polysacharidov (EPS) vybraných termofilných a halofilných mikroorganizmov. Po primárnom screeningu vybraných kultúr bola experimentálna časť tejto práce ďalej venovaná halofilnému archea Haloferax mediterranei. Cieľom tejto práce bola produkcia a charakterizácia polymérov a posúdenie biotechnologického potenciálu použitých extremofilných kultúr ako producentov EPS. Počas kultivácie H. mediterranei boli použité 3 základné média, ktoré boli následne optimalizované v prospech produkcie EPS. Získané precipitáty boli podrobené analýze pomocou GPC, FTIR a UHPLC-UV-ESI-MS/MS, na základe čoho bolo možné bližšie charakterizovať získaný produkt. Tieto experimenty dokázali, že so stúpajúcou koncentráciou NaCl v médiu, klesá výťažok polysacharidov a ich produkciu nepodporujú ani vysoké koncentrácie MgSO4 a KCl v médiu. Hlavnou komponentou polysacharidov vyprodukovaných H. mediterranei, je manóza, no v závislosti od použitého média môže obsahovať aj glukózu, galaktózu, ribózu alebo N-acetylglukosamin.
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Evaluation of washing effect on material properties after 3D DLP printing
Uvíra, Dominik ; Jaroš, Aleš (referee) ; Zemčík, Oskar (advisor)
This thesis focuses on the influence of washing on the mechanical properties of 3D DLP printed parts. The aim of the thesis was to experimentally determine the impact of washing agents with different wash durations on the mechanical properties of 3D printed parts using DLP technology. The research describes the devices and materials used. Furthermore, an analysis of washing 3D DLP printed parts is conducted, including a description of polymer dissolution, types of washing agents, and washing methods. Based on the research, materials were selected, including Standard resin, ABS-like resin, and Tough resin. The used washing agents are IPA, Simple Green industrial degreaser, DPM, and a special uncured resin remover called EasyClean. Samples were produced on the DLP 3D printer Anycubic Photon D2, and printing profiles were established based on the research part and own calibration. In the first experiment, the effectiveness of the agents in removing uncured resin was monitored. This was followed by an experimental evaluation of the tensile properties of the prepared samples. Furthermore, the notch toughness of each material was evaluated. In both cases, an analysis of fracture surfaces was conducted. Based on the achieved results, optimal washing durations were determined for all material and rinsing agent combinations, and areas of application were recommended. Subsequently, a custom rinsing agent combining low cost and good mechanical properties was proposed. The final part of the work consists of an economic evaluation of the various rinsing agents, resulting in specific recommendations for purchasing rinsing agents and rinsing duration.
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Analysis of hazardous metals in rPET granulate
Souček, Elena ; Řezáčová, Veronika (referee) ; Komendová, Renata (advisor)
Production of polymer products has increased rapidly in recent decades. Especially in food industry as a packaging it gained a dominant position when it replaced previously used materials. Due to the direct risk for human health it is necessary to be careful and pay attention to their composition. It is also necessary to develop methods to properly recycle and reuse already used material, not only produce new products. This thesis deals with the study of the content of risk elements in PET regranulate. The samples were completely decomposed by microwave radiation in an environment of concentrated sulfuric and nitric acid. They were subsequently analyzed by atomic absorption spectrometry (AAS). Flame atomization technique (FAAS) was used to determine Sb and Zn and electrothermal atomization (ETAAS) to determine Cd, Cr, Pb, Cu and Ni. This method was also used to study migration of antimony from samples to food simulant under different conditions (temperature, pH). This thesis follows up on the thesis of Mrs. Kryštofová who studied recycled PET flakes.
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Study on biodegradation of synthetic biobased polyesters
Guziurová, Pavlína ; Sedláček, Petr (referee) ; Obruča, Stanislav (advisor)
Tato práce se zabývá degradačními vlastnostmi polyesterových polymerů (PBS s inkorporovaným dilinoleovým sukcinátem v různých hmotnostních procentech) v simulovaných tělních tekutinách a odhaluje menší změny vlastností. Byla zkoumána také bakteriální degradace a analýza ukazuje významnější rozdíly ve výsledcích gelové permeační chromatografie (GPC) a skenovacího elektronového mikroskopu (SEM). Zatímco převažuje abiotická degradace, bakteriální prostředí vede k vyšším úrovním degradace než simulované tělní tekutiny, což naznačuje potenciální využití v obalové technice nebo zemědělství. Nižší náchylnost na abiotickou degradaci však otevírá nové možnosti pro další výzkum mechanismů bakteriální a enzymatické degradace pro ekologicky udržitelné alternativy v různých průmyslových odvětvích.
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An investigation of friction and lubrication of coated hip joint replacement
Balcárek, Ondřej ; Horák, Zdeněk (referee) ; Nečas, David (advisor)
The thesis focused on studying the effects of a new hydrogel coating and material combinations on the coefficient of friction and formation of lubricating film in the conformal contact of hip joint replacement. Experiments were conducted using a ball-on-cup configuration with a hip pendulum simulator. The formation of the lubricating film was observed using fluorescence microscopy. The results showed that the application of the coating did not have a clear impact on the coefficient of friction. However, for pairs with a coated cup, there was a reduction in CoF by approximately 20%. Generally, lower friction was observed when using a ceramic joint head. Surprisingly, even more interesting results were obtained in the lubrication analysis, where the use of metal heads led to a reduction in the thickness of the lubricating layer. Ceramic pairs exhibited very stable behavior. In addition to friction and lubrication, the topography of the implants was further evaluated, and their wettability was analysed. Although the polymer coating was expected to be highly hydrophilic, the surface properties were only slightly influenced, which partly explains why there was no significant improvement in the tribological behavior of the replacement. As the coating applied is already patented and its effectiveness in reducing wear has been clearly demonstrated, it is appropriate to investigate this issue further, with more attention being paid to long-term experiments. Based on the obtained data, it appears that the short-term benefits of the coating are practically negligible. However, it is important to highlight that, except for minor exceptions, the application of the coating did not lead to a deterioration of properties, which is a significant outcome of this work.
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Preparation and study of a series of diketopyrrolopyrrole (DPP)-based polymers as photoactive substances
Solanský, Lukáš ; Richtár, Jan (referee) ; Cigánek, Martin (advisor)
The present diploma thesis deals with polymers based on organic pigments, their preparation, characterization and use as photoactive substances with a focus on artificial photosynthesis. The experimental part is devoted to the preparation of diketopyrrolopyrrole (DPP) based polymers. 7 DPP derivatives with 5 different side chains were prepared. The preparation of DPP polymers by Stille cross-coupling reaction and direct arylation were compared. Due to the higher efficiency and lower complexity of direct arylation, this polymerization method was used to prepare a series of 20 polymers consisting of a combination of 5 DPP derivatives and 4 comonomers. In the synthesis of several of the resulting polymers, the formation of an insoluble moiety was observed which could not be characterized by available methods, and even the subsequent application of such materials is not possible due to this. On the basis of the data obtained, it became apparent that in particular the bulky adamantane group and the comonomer tetrafluorobenzene were not suitable for the preparation of polymers, as they resulted in very limited soluble materials which, moreover, had a low degree of polymerization. In contrast, polymers containing butyl-TEG, octadecane, the comonomer thiophene and partially benzothiadiazole had degrees of polymerization in the range of 10-33 and exhibited excellent spectral and optoelectric properties. Tests of photocatalytic hydrogen evolution using DPP polymers are under development, but hydrogen was not demonstrably detected in initial measurements on selected polymer materials (P14 and P20).
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Design of the Anchorage Length of FRP Reinforcement with the Influence of Extreme Temperature Loading Due to the Effects of Fire
Vašátko, David ; Zlámal, Martin ; Čairović, Đorđe ; Lagiň, Juraj ; Zlámalová, Pavlína ; Štěpánek, Petr
The extremely high temperatures from fire exposure have a negative impact on the behaviour of reinforced concrete structures regardless of the type of reinforcement used. The reduced mechanical properties of the materials need to be taken into account in the design of the structure, including anchorage length, to ensure that the reinforcement does not detach from the concrete. In the case of Fibre Reinforced Polymers (FRP) reinforcement, there are limited number of codes addressing the design issues in a fire situation. This article, based on experimental findings, proposes a procedure for determining anchorage length of FRP reinforcement under elevated temperatures.
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Explosive Shapes in Smoothed-Particle Hydrodynamics (SPH) Method for Structural Analysis of Concrete Members
Jindra, Daniel ; Hradil, Petr ; Kala, Jiří
The study compares performances of numerical finite element (FEM) analyses of simply supported concrete slabs reinforced by BFRP bars (basalt fibre reinforced polymer) exposed to close-range (1 m distance) explosions. A sensitivity study of slab deflection and reinforcement strain on various shapes of TNT charges is conducted. Smoothed-particle hydrodynamics (SPH) method is used to model the geometry of the TNT charges (variously rotated cylinders, cubes and spheres), detonation and interaction with the concrete slab, which is modelled by Lagrangian mesh. Karagozian and Case (K&C) nonlinear material model is used for concrete slabs exposed to high-velocity impact load. Finite element analyses have been conducted in explicit solvers suitable for high strain rates. The results of numerical simulations are compared with physical experiment data obtained from the scientific literature.
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Study of interaction of charged catanionic vesicles with oppositely charged polyelectrolytes
Havlíková, Martina ; Lehocký, Marián (referee) ; Táborský, Petr (referee) ; Mravec, Filip (advisor)
The presented dissertation is focused on positively charged catanionic vesicles and their interactions with oppositely charged hyaluronan. The catanionic vesicles were composed of ion pair amphiphile of hexadecyltrimethylammonium-dodecyl sulfate (HTMA-DS), a positively charged double-chain surfactant that electrostatically stabilized the vesicles and cholesterol. Cholesterol may strongly affect the physico-chemical properties of the vesicles, therefore it was necessary to determine its optimal amount in the membrane. Especially, the size and stability of vesicles were studied by dynamic and electrophoretic light scattering, membrane microviscosity by fluorescence anisotropy and hydration of the outer part of the membrane by generalized polarization. It was found that vesicles show ideal properties at a cholesterol content about 40 mol.%. These catanionic vesicles interacted with hyaluronan regardless of its molecular weight. Visible aggregates were observed around their isoelectric point, but they disintegrated with increasing polymer concentration. However, this decay was different for different hyaluronan molecular weights. An increase in ionic strength, or more precisely concentration of sodium chloride above 25 mM had a destabilizing effect on both uncoated and hyaluronan coated vesicles. It was also interesting that increasing the ionic strength affected the microviscosity of the membrane, which became more fluid, but there were no significant changes in the hydration of its outer part. The presented work is also focused on the preparation and characterization of a new type of catanionic vesicles, where the cationic surfactants HTMAB was replaced by Septonex. The same methods were chosen for their characterization as in the case of the HTMA-DS vesicles. This exchange of surfactants had a major effect on the resulting properties of the vesicles, which are stable even at very low cholesterol content. In accordance with long-term stability, a suitable concentration of cholesterol was chosen from 15 mol.% and higher.
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Development of Film Thickness in Elastohydrodynamically Lubricated Compliant Contacts
Křupka, Jiří ; Fillot, Nicolas (referee) ; Glovnea, Romeo (referee) ; Křupka, Ivan (advisor)
Mazání polymerních strojních součástí, jako jsou polymerní ozubená kola, je v současné době předmětem zájmu mnoha strojírenských aplikací z hlediska simulace mazacích procesů a optimalizace tribologických podmínek pro zvýšení výkonnosti těchto součástí. Předkládaná disertační práce se zabývá experimentální studií vývoje tloušťky kapalinového filmu v elastohydrodynamicky mazaných poddajných kontaktech. Hlavním cílem práce je objasnit formování tloušťky filmu v poddajných kontaktech v přechodové oblasti (TR) mezi isoviscous-elastic (I-E) a piezoviscous-elastic (P-E) režimem elastohydrodynamického mazání (EHL). Za tímto účelem byly provedeny laboratorní experimenty na rotačním optickém tribometru v konfiguraci kulička na disku, ve kterých byla implementována metoda optické chromatické interferometrie. Experimentálně byl analyzován vliv jak reologické odezvy maziva, tak konstitutivní viskoelastické odezvy polymeru na tvorbu tloušťky kapalinového filmu. Na základě výsledků byla dokumentována nízká platnost predikčních modelů tloušťky filmu I-E a P-E v oblasti TR. Výsledky prezentované v této práci rozšiřují poznatky o tvorbě mazacího filmu v poddajných kontaktech pracujících v režimu EHL a mohou tak být zohledněny při návrhu polymerních strojních součástí nebo při řízení mazacích procesů.
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