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Zinc in food suplements
Sauchanka, Katsiaryna ; Suková, Petra (referee) ; Řezáčová, Veronika (advisor)
The aim of this bachelor thesis was to determine zinc in the dietary supplements by the voltammetric method. The general properties of zinc, its occurrence, toxicity and influence on human health are described in the first part. Next the methods, including a detailed description of the voltammetric analysis, are summarized. The experimental part is focused on the process of optimization of the conditions for zinc voltammetric analysis and the application of the optimised method on real samples.
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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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Influence of zinc loss during the sintering on permeability/inductance of ferrite ceramics
Kvapilová, Vendula ; Ptáček, Petr (referee) ; Šoukal, František (advisor)
The diploma thesis is focused on the investigation of the effect of zinc release during ferritic sintering on the permeability/inductance of ferrite ceramics. The theoretical part deals with the position of ferrites among other ceramic materials. It describes the basic characteristics of ferrites, their crystal structure and finally the problems that are directly related to their production and which fundamentally affect the magnetic properties of ferrites. In the second part of the work, the influence of the temperature and time of sintering and the position of the cores in the furnace during firing on the loss of zinc from the sample and subsequently on the electromagnetic properties of the prepared test specimens from industrial raw material mixtures was investigated. These are initial experiments, which will be followed by further research aimed at eliminating the problem of zinc loss in the production of Mn-Zn ferrites.
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Properties and in vitro Degradation of Metalic Biodegradable Materials
Ročňáková, Ivana ; Trojanová, Zuzanka (referee) ; Vojtěch,, Dalibor (referee) ; Podrábský, Tomáš (advisor)
Biodegradable metallic materials for medical applications have received considerable attention in recent years. The main reason is that they provide high potential for fabrication of temporal orthopedic implants such as bone fixation devices. Magnesium is an excellent candidate for fabrication of biodegradable implants due to its biocompatibility, mechanical properties similar to human bone and relevance for biological body functions. The fast degradation rate of magnesium and its biodegradable alloys in physiological environment limits its clinical application. Another attractive material in the field of biodegradable materials is zinc, which is among the essential elements in human body. Zinc exhibits an excellent corrosion resistance, and inferior biocompatibility compared to with magnesium. Hence, surface modification to form a hard, dense/porous, biocompatible and corrosion resistant modified layer has become an interesting topic in magnesium base biomaterials. Since hydroxyapatite is well tolerated by living organisms and in addition, improves the bone growth, it appears to be excellent candidate for such coatings on surface of biodegradable materials (e.g. Mg, Zn). This thesis is focused on comparison of corrosion behavior of pure non ferrous metals (Mg, Zn) and metals coated with hydroxyapatite, in simulated body fluids. The present approach is the use of modified atmospheric plasma spray technology to produce the hydroxyapatite coatings – suspension spraying. Composition and structure of the coatings and corrosion products were studied by light microscopy, scanning electron microscopy equipped with energy dispersive microanalyzer and X-ray diffraction. Corrosion of Mg and Zn samples was monitored by weight loss and determined by X ray and micro-tomography. The application of the HA coating resulted in decrease of corrosion rate of pure Mg. The corrosion rate of coated Mg samples was lower by 27,3 % in comparison with the corrosion rate of pure non coated Mg. Corrosion degradation of uncoated and coated Zn samples was minimal. The aplication of HA on the non ferrous surface appears to be a very promising method to improve corrosion and biological properties of these biodegradable materials.
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The study of zinc influence on Portland cement hydration.
Ptáček, Martin ; Janča, Martin (referee) ; Šiler, Pavel (advisor)
The topic of this work is the monitoring of the effect of zinc on the hydration process in Portland mixed cement (specifically with the addition of finely ground granulated blast-furnace slag, high temperature fly ash and fluidized bed combustion filter ash). How much zinc and at what time it remains in the pore solution during hydration. Activation energy of a mixture of cement with zinc in the form of soluble salts (Zn(NO3)2.6H2O and ZnCl2) and insoluble oxide (ZnO) by isothermal calorimetry was also investigated. The XRF method has shown composition during hydration. The zinc retardation effect was investigated by isothermal calorimetry and activation energy was calculated using this method. The XRF and ICP-OES methods were used to measure the zinc content of the pore solution. And the amount of portlandite was monitored by the DTA and XRF method.
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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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Production of castings from aluminum alloy Unifont 90
Chvátal, Pavel ; Lána, Ivo (referee) ; Kaňa, Václav (advisor)
The diploma project deals with the aluminum foundry alloy Unifont-90. The aim of the project was to observe the effect of different pouring temperature and wall thickness of the casting on the mechanical properties and microstructure of the material. The theoretical part of the project describes selected properties of aluminum foundry alloys and foundry processes used in their casting. In the experimental part, measurements of mechanical properties and microstructure of the material of the investigated Unifont-90 alloy took place.
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Generation of volatile zinc chelates from aqueous matrix
Kračmarová, Aneta ; Nováková, Eliška (advisor) ; Červený, Václav (referee)
The topic of this work was optimization of the conditions for the generation of volatile zinc chelates. The aim was to develop an alternative method for generating volatile Zn speciates to its reduction by sodium tetrahydridoborate. Detection was carried out by atomic absorption spectrometry. Optimization of the conditions of the chelation reaction itself included the selection of a suitable chelating agent and appropriate modifiers, pH adjustment, suitable reagent and carrier gas flow rates, and appropriate apparatus arrangement. The following method characteristics were obtained under optimal conditions: LOD 1.55 mg L-1 , LOQ 5.17 mg L-1 and sensitivity 0.245 s L mg-1 . The repeatability was 13,7 %. The addition of modifiers was then tested to increase the efficiency of generation of volatile zinc chelates. Potential modifiers included transition metals, organic solvents, heterocyclic organic compounds, compounds from the carbamate group and surfactants. The heterocyclic 1,10-phenanthroline and the carbamate NaPDC were included in the optimal conditions because without them it was not possible to distinguish the signal from noise. Acetonitrile proved to be the most effective modifier, increasing the efficiency to 1547 %. With the addition of acetonitrile, the LOD decreased to 0.191 mg L-1 , the...
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Testování tolerance vybraných genotypů konopí vůči fytotoxickým účinkům zinku
Kabina, Viktoriia
This bachelor thesis was aimed at testing the tolerance of selected hemp genotypes to the phytotoxic effects of zinc. In the theoretical part, the main aspects of the toxic effect of heavy metals on plants were analyzed. Here the sources of environmental contamination with heavy metals, the uptake of heavy metals by plants, the effects of heavy metals on plants and their tolerance mechanisms are described, and the phenomenon of phytoremediation as a method of soil purification is also described. In the practical part, the influence of different zinc concentrations on selected hemp genotypes, namely French variety Felina 32 and Hungarian variety Monoica, were studied. The growth parameters of the experimental plants and the pigment content in the leaves of the plants were determined. The experiments did not prove serious effects of zinc on experimental plants, except for high concentrations in individual cases. Nevertheless, it can be said that in comparison with the Monoica variety, representatives of the Felina 32 variety were more sensitive to the presence of zinc in the soil.
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Analýza obsahu významných nutrientů v tropickém ovoci a v jejich škůdcích
Remencová, Julie
The diploma thesis is focused on analysis of selected elements of tropical fruits and their pests. The aim of the thesis was to find a relationship between mineral content of tropical fruits and their pests and to clarify whether the found correlations can be used for targeted pest management. The mediterranean fruit fly (Ceratitis capitata) and peach fruit fly (Bactrocera zonata) are one of the most dangerous and economically important species of Tephritidae family causing significant economical looses estimated in hundreds of millions of dollars per year. The theoretical part focuses on general description, production and consumption, chemical content and importance of individual analysed tropical fruit species. Literature review deals with selected elements – calcium, magnesium, iron, zinc, manganese and copper from the point of view of importance in human nutrition. The practical part describes analyses of the above mentioned elements using flame absorption spectrometry in samples of mango (Mangifera indica), mandarin (Citrus unshiu), kaki (Diospyros kaki) and pomegranate (Punica granatum) and samples of two fruit fly species C. capitata and B. zonata. From the correlations of elements contents in tropical fruits and their pests follows that the determination of calcium can be used for identification of the origin of the pest because a significant correlation was found only between the content of calcium in mandarin and C. capitata fed on mandarin.
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