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Interaction between TiAl melt and coated oxide refractories
Dočekalová, Kateřina ; Dlouhý, Antonín ; Zemčík, L. ; Fiala, J.
The present study focuses on reactions between ceramic crucibles and molten TiAl intermetallics. Coating strategies are investigated that exhibit a potential in slowing down the decomposition of the crucible wall. Uncoated crucibles (system TiAl melt - Al2O3 crucible) and crucibles with the coat (system TiAl melt - CaO coat - Al2O3 crucible) were used in melting and casting experiments. The reference state of the coated crucible before the melting trial was also investigated. Results of the SEM, EDAX and X-ray diffraction analysis contributed to the identification of the reaction zone and its chemical composition. The melt contamination with oxide inclusions results from the erosion process in which individual components of the melt diffuse along grain boundaries of the refractory and activate chemical reactions that decompose the crucible wall. Assessment of thermodynamic parameters associated with the chemical reactions helped in identifying the nature of the erosion process.
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Survey and assessment of the National museum building in Prague
Drdácký, Miloš ; Slížková, Zuzana
The report presents results of a complex survey of the health conditions and damages and failures of the building of the National museum in Prague. It further summarizes scientific investigations of the loads, namely of winds in situ as well as on models in a climatic wind tunnel where also soiling was tested. The results of material analyses and public attitude to soiling and failures on the façade are involved, too. The report has a rich photographic annex.
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Costs reduction in production of Al-alloy castings
Nováková, Lucie ; Lána, Ivo (referee) ; Roučka, Jaromír (advisor)
This thesis deals with solving the most serious internal defects in castings made of aluminum alloys which are cast in sand molds in Slévárna a modelárna Nové Ransko Ltd. The problem solving contains a description of the problematic castings with the investigation of the structure and phases and subsequent detailed analysis of their production. The Author of this thesis also examines the influence of Fe and Mn on a possible formation of the internal porosity with the help of test meltings with the evaluation of the internal structural change. The Author’s design solution is a close checking of chemical composition with regard to the ratio Mn / Fe present in the alloy, the purchase of Foundry Degassing Unit to reduce gassiness of melted metals and better control of gassiness with the help of the appropriate equipment for the density Dichte index.
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The Role of Gut Microbiota and Lipopolysachaide Content of the Diet in the Development, Maturation and Function of the Immune System
Hrnčíř, Tomáš ; Tlaskalová - Hogenová, Helena (advisor) ; Prokešová, Ludmila (referee) ; Macela, Aleš (referee)
Mammals are essentially born germ-free but the epithelial surfaces are promptly colonized by astounding numbers of bacteria soon after birth. The most extensive microbial community is harboured by the distal intestine. The gut microbiota outnumbers ~10 times the total number of our somatic and germ cells. The hostmicrobiota relationship has evolved to become mutually beneficial. Studies in germfree mice have shown that gut microbiota is essential for the proper development of the immune system. The pivotal role of the innate immune system in the complex and dynamic host-microbiota interactions has become increasingly evident. The principal aims of the present study were: firstly, to determine whether LPS-rich sterile diet can promote maturation of the immune system in germ-free mice, secondly, to elucidate whether gut microbiota and LPS-rich sterile diet influence the LPS susceptibility, and finally, to investigate a role of the adaptive immunity in endotoxin shock. Our data clearly show that both live gut microbiota and LPS-rich sterile diet increase susceptibility to endotoxin shock. Further, we demonstrate that immunodeficient SCID mice, which lack mature B and T cells, are more sensitive to endotoxin shock than immunocompetent Balb/c mice. In addition, we show that not only live gut microbiota but also...
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Changes in structure and phase composition in the surface of tram rail
Švábenská, Eva ; Roupcová, Pavla ; Schneeweiss, Oldřich
We have investigated structure and phase composition of surface layer of tram rails after long time running and the results were compared with those obtained on the original part of material. Changes due to effects of severe plastic deformation together with thermal shocks by friction process were expected. The information about structure and phase composition was obtained by optical and scanning electron microscopy, X-Ray Powder Diffraction, Mössbauer Spectroscopy and Glow Discharge Emission Spectroscopy (GDOES) and this was completed by microhardness measurements. The results show that the surface layer in comparison with the original material exhibits important changes in grain structure, an increase in microhardness and high content of iron oxide and hydrooxides. According to the depth profile of the chemical composition measured by GDOES there is an increase in carbon content in the surface layer which can be effect of up-hill diffusion.
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Analysis of biologically active substances by capillary electromigration methods
Jáč, Pavel ; Polášek, Miroslav (advisor) ; Tesařová, Eva (referee) ; Jokl, Vladimír (referee)
This thesis deals with the utilization of capillary electromigration methods for the analysis of biologically active substances. In the Theoretical part historical progress, instrumentation and separation mechanisms of different electromigration methods are discussed. In addition brief overviews mapping chiral separation by means of CE and complex-formation for the separation selectivity enhancement are also included. Two final sections of Theoretical part are focused on specific features of method optimization and method validation in CE. Practical part is presented by comments on published papers, which were attached in full text version to Addendum. The results presented in this thesis cover two areas. First area is focused on the utilization of electromigration methods for the analysis of polyphenols in plant materials while second area is dealing with the development, optimization and validation of CE methods for quality control of pharmaceuticals and/or nutraceuticals. The first area of the practical part overviews new trends (papers published between 1999- 2005) in the analysis of polyphenols by CE. The second paper focused on the analysis of polyphenols is an original investigation of new kind of BGE based on complex-forming reagent - sodium tungstate - that was applied in the assay of...
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