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Biodegradable bones implants based on iron
Hrabovský, Jan ; Zatloukal, Miroslav (referee) ; Sedlaříková, Marie (advisor)
This work deals with a current topic, which are biodegradable bone implants. These implants seem to be a suitable candidate for temporary fixations, with their gradual decomposition. An important parameter is not only the mechanical properties so that the material can withstand the load, but above all the corrosion properties and the degradation process. This work introduces the physiology of bone, trace elements and also describes current trends in the field of implants. The last part is a theoretical introduction to cross-stage processes. The practical part is focused on the preparation of iron-based samples with various dopants, subsequent annealing and analysis.
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Effect of microstructure on mechanisms of plastic deformation in fine-grained magnesium alloys
Minárik, Peter
In this work were studied effects of the grain refinement on the mechanical properties and the corrosion resistance of magnesium alloys potential for medical applications - AE21 and AE42. Mechanical properties changed after ECAP pressing in consistency with literature data. Enhanced corrosion resistance in AE42 alloy was achieved by the grain refinement. Corrosion layer created on the surface was observed by light and electron microscopy. Effect of the grain size on the character of the corrosion layer was investigated. AE42 alloy is suitable for further investigation as potential biodegradable material. AE21 alloy was excluded from further investigation due to low corrosion resistance even after ECAP treatment.
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Study of deformation processes in hexagonal materials
Čapek, Jan
The deformation mechanisms of commercially pure magnesium using advanced in-situ methods were investigated in the present work. Compression and tensile test were done at room temperature. Simultaneously, the neutron diffraction was measured and the acoustic emission was recorded. The microstructure of the deformed material was also studied by means of optical microscopy and electron back-scattered diffraction. These measurements provided information about twin nucleation and growth, microstructure changes and the influence of the orientation of grains on the number of twins and their shape. The values obtained were compared to the Elasto-Plastic Self-Consistent model, which provides information about the activity of deformation mechanisms. We focused on clarifying the influence of twinning activity on asymmetry between tensile and compression deformation. Powered by TCPDF (www.tcpdf.org)
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Mechanical properties of a novel magnesium WN43 alloy prepared by spark plasma sintering
Greš, Adam ; Knapek, Michal (advisor) ; Dobroň, Patrik (referee)
Title: Mechanical properties of a novel magnesium WN43 alloy prepared by spark plasma sintering Author: Adam Greš Department: Department of Physics of Materials Supervisor: RNDr. Michal Knapek, Ph.D., Department of Physics of Materials Abstract: Properties such as low modulus of elasticity, low toxicity, and biode- gradability make magnesium alloys interesting candidates for medical applicati- ons. To avoid potentially harmful effects of rare earth mischmetal present in the commercial WE43 alloys, it has been replaced in this study with pure neody- mium, which exhibits lower toxicity. To achieve high control over the material microstructure, it was prepared using the spark plasma sintering technique. This study focuses on exploring the mechanical properties of the novel WN43 alloy using compression and tensile testing accompanied by the acoustic emission tech- nique. Ultimate compressive strength and ductility were observed to improve significantly with higher sintering temperatures. In order to obtain better insi- ghts into microscopic aspects of the deformation mechanisms, EBSD images of the samples were taken at multiple points during deformation. It was shown that around the yield point twin nucleation produces strong acoustic emission signal, while later stages of deformation are mostly accommodated by...
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Research and development of a technology of hard anodization of nonferrous alloys
Remešová, Michaela ; Kudláček,, Jan (referee) ; Vidal, Salvador Pané (referee) ; Kaiser, Jozef (advisor)
Práce je zaměřena na výzkum a vývoj technologie přípravy tvrdých anodických vrstev na třech různých typech neželezných materiálů a to (i) hliníkové slitině (AA1050), (ii) čistém hořčíku (99.9% Mg) a (iii) zinkové slitině (ZnTi2). Vhodnou kombinací anodizačních podmínek (napětí, proudová hustota, teplota a složení elektrolytu atd.) lze vytvářet anodické vrstvy s rozdílnými vlastnostmi. V rámci předložené práce byl prokázán vliv předúpravy a anodizačních podmínek na vzhled, morfologii, tloušťku a tvrdost vytvořených anodických vrstev. Pro zvýšení tribologických vlastností a tvrdosti byly anodické vrstvy přímo dopovány Al2O3 částicemi nebo kombinací Al2O3 a PTFE částic během anodizačního procesu. Teoretická část práce popisuje základní principy anodizace, metody používané v průmyslové praxi a v práci je také popsán technologický proces. Experimentální část je rozdělena na tři základní části. První část se věnuje anodické oxidaci hliníkové slitiny AA1050. Druhá část je zaměřena na anodizaci čistého hořčíku a poslední část je zaměřena na anodizaci zinkové slitiny ZnTi2, která není tak známá jako anodizace hliníku.
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Multi-element Systems of Biomaterials Based on Magnesium and Zinc
Hasoňová, Michaela ; Nový, František (referee) ; Vojtěch, Dalibor (referee) ; Doležal, Pavel (advisor)
Dissertation thesis deals with basic research in the field of materials from pure Zn powders and Mg, Zn, and Ca binary mixtures prepared by powder metallurgy. General powder metallurgy principles and methods, a brief description of Mg, Zn, and Ca structure and properties, and the latest research in the field of bulk materials preparation from these elements via powder metallurgy are summarized in the theoretical part of the thesis. The experimental part focuses on the preparation of materials from finer and coarser Zn powder particles by hot pressing at 300 and 400 °C using the pressure of 100, 200, 300, 400, and 500 MPa. Binary mixtures based on Mg with the addition of Zn or Ca were prepared by hot pressing in the solid-state (300 °C) and hot pressing in the semi-solid state (400 °C, 450 °C in the case of Mg-Ca system) using the pressure of 500 MPa. Binary mixtures based on Zn with the addition of Mg or Ca were prepared by hot pressing in the semi-solid state (400 °C) using the pressure of 500 MPa. The prepared materials were evaluated in terms of microstructure, elemental and phase composition, microhardness, flexural strength, and fractography. The results showed that in the case of processed from pure Zn powders, a better combination of the flexural strength and displacement was achieved in the case of the finer Zn powder, namely in the material prepared at a temperature of 400 °C and a pressure of 500 MPa. In the case of mixtures, the best connection between the powder particles was achieved in the case of a material based on finer Zn powder with 0.5 wt.% of Mg, which had a significant effect on the achieved values of flexural strength and displacement. The amount of minor powder in the mixture had a significant effect on the prepared material structure and phase composition, while the processing conditions influenced the reached strength characteristics and fracture mechanism.
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Structure and properties of Hydroxyapatite-Magnesium composites produced by the means of current assisted infiltration sintering
Casas Luna, Mariano ; Obrtlík,, Karel (referee) ; Georgarakis, Konstantinos (referee) ; Čelko, Ladislav (advisor)
Hořčík a kompozity fosforečnanu vápenatého jsou slibnými materiály pro biodegradabilní a nosné implantáty určené pro regeneraci kostí. Předložená práce je zaměřena na návrh, zpracování a charakterizaci vnitřně propojených kompozitů hořčíku s fosforečnanem vápenatým (Mg/CaP). Fosforečnany vápenaté jako jsou hydroxyapatit (HA), kalcium-deficitní hydroxyapatit (CDHA) a fosforečnan vápenatý (TCP) byly syntetizovány a použity pro výrobu skafoldů s kontrolovanou porozitou pomocí metody robocastingu. Byly připraveny porézní předlisky s ortogonální mřížkou a s vnitřními makropóry o velikosti ~500 µm, které byly následně slinovány za teploty 1100 °C po dobu 5 hodin. Vnitřně propojené Mg/CaP kompozity byly připraveny infiltrací čistého hořčíku a hořčíkových slitin obsahujících malá množství vápníku nebo zinku, například 0,2 hm.% vápníku a 1 hm.% zinku do porézních keramických skafoldů. Infiltrace byla provedena pomocí námi vyvinuté a nově popsané metody známé jako “Proudem asistovaná slinovací infiltrace” (z angl. Current Assisted Metal Infiltration (CAMI)). CAMI metoda umožňuje do 15 minut infiltrovat porézní keramický předlisek roztaveným kovem. Pulzujícím elektrickým proudem bylo dosaženo rychlého tavení a následného tuhnutí Mg/CaP kompozitů. Fyzikálně-chemické vlastnosti finálních vnitřně propojených kompozitů byly stanoveny pomocí rastrovací elektronové mikroskopie, počítačové mikro-tomografie, rentgenové difrakční analýzy a optické mikroskopie za účelem stanovení fázové distribuce a interakce mezi materiály. Kromě toho byla u připravených kompozitů hodnocena jejich mechanická pevnost v tlaku, degradační rychlost pomocí různých metod a biokompatibilita spolu s pokusem o uvedení těchto typů materiálů jako potenciálních degradabilních biomateriálů určených pro výrobu desek a/nebo šroubů pro ortopedické aplikace.
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Interakce mezi minerálnimi prvky v dietě brojlerů a jeji vliv na vlastnosti svaloviny
Prokop, Jakub
Diploma thesis deals with influence of mineral elements level in the diet of broiler chickens. Primary observe their importance in meat production with high nutritional and sensory quality. In experiment we tried to modulate the performance of chickens by changing the level of zinc (24 g, 204 g), calcium (2 g, 15 g) and magnesium (1,5 g, 4,5 g) and test the influence on sensory attributes of breast and tight meat. After slaughter in the age of 36 days the meat was processed and frozen stored. In sensory analysis (after heat processing) color, texture, odour, presence of strange odour, tenderness, juiciness, taste and presence of strange taste was judge. We discovered that different level of zinc has negative influence on the odour of tight meat (85,50+-2,108; 77,03+-3,333). Higher level of calcium and magnesium for the breast meat had positive influence on the color (83,53+-2,663; 88,50+-1,731) and negative influence on odour (86,10+-2,428; 76,66+-3,341), chewiness (77,73+-4,157; 63,33+-4,607) and taste (71,83+-4,325; 57,75+-4,532). In the end we can conclude that addition of different levels on mineral elements can influence organoleptic properties of meat and its acceptance for the consumer. It is necessary to do more experiments in this subject in the future.
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Vliv skladování na obsah vybraných nutrientů v slepičích vejcích
Slováček, Robin
The aim of this master´s thesis was to determinate selected nutrients in hen eggs depending on the time of their storage. The content of nutrients in hen albumen, hen yolk and hen melange was measured in fresh eggs ang in storaged eggs after one, two, eight, fiveteen, twenty nine, forty three and fifty seven days. Teoretical part of thesis is focused on chemical composition of hen egg, breeding, history, storage and consumption. Another part of thesis deals with selected nutrients, specifically by magnesium, copper, calcium, zinc and iron. In practical part the results are presented. The content of these elements was determined with using atomic absorption spectometry. The results show that the storage time did not have an effect on the contents of the selected elements in the eggs. Formula clause:hen egg, magnesium, copper, calcium, iron, zinc, atomic absorption spectrometry
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Vliv skladování na obsah vybraných nutrientů v křepelčích vejcích
Piskořová, Daniela
The aim of this master’s thesis was to determine the total contents of selected nutrients (magnesium, copper, calcium, zinc and iron) in quail eggs during the time of their storage. The contents of elements were measured in fresh eggs and then after first, second, third, eighth, fifteenth, twenty – ninth, forty – third and fifty – seventh day of storage. Theoretical part is focused on the production and importance of eggs, their creation and chemical composition. Additionally, this part deals with the more detailed characteristics of aforementioned elements and with their relationship to human nutrition. The practical part includes the results of measured contents of elements in whole egg, yolk and egg white. The analysis was carried out using atomic absorption spectrometry. The results show that the time of storing has no effect on the contents of selected elements in quail eggs.
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