Corrosion and aesthetic properties of galvanized thin-walled sheets and profiles

Diplomová práce se zabývá hodnocením korozních a estetických vlastnosti pozinkovaných tenkostěnných plechů a profilů. Popisuje metody tvorby zinkových ochranných vrstev a také tvorbu tenkostěnných profilů. V experimentální části bylo provedeno nedestruktivní a metalografické měření tloušťky zinkové vrstvy. V kondenzační komoře byla provedena zkouška odolnosti ochranné vrstvy. Bylo provedeno korozní a estetické vyhodnocení ochranné vrstvy před a po zkoušce v kondenzační komoře.The thesis deals with the evaluation of corrosion and aesthetic properties of galvanized thin-walled sheets and profiles. It describes methods of formation of zinc coatings and also the formation of thin-walled profiles. In the experimental part, non-destructive and metallographic measurements of zinc layer thickness were performed. The protective layer was tested for resistance in the condensation chamber. Corrosion and aesthetic evaluation of the protective layer was performed before and after the test in the condensation chamber.636 - Katedra materiálového inženýrstvídobř

Properties and application of aluminum alloys in automotive industry

Import 22/07/2015Tato bakalářská práce je zaměřena na hliníkové slitiny a jejich použití v automobilovém průmyslu. V teoretické části této práce jsou popsány jednotlivé slitiny Al, jejich vlastnosti, použití a předpokládaný vývoj užití pro další desetiletí. Pro praktickou část této práce byla vybrána rozeta vyrobena z materiálu AW 7075, bylo provedeno ověření shody materiálu s příslušnou normou ČSN EN 573 a byla pozorována mikrostruktura tohoto materiálu.The aim of this bachelor thesis is to describe the use of aluminium alloy in automotive. Theoretical part covers the detailed description of each alloy along with their qualities and expected usage for near future. For practical part I have chosen a sprocket made from AW 7075 material. A verification check for the material unity has been performed according to quota ČSN EN 573. Microstructure of the substance was monitored.636 - Katedra materiálového inženýrstvívýborn

Effect of alkali metal promoters on catalytic performance of Co-based catalysts in selective hydrogenation of aniline to cyclohexylamine

In this study, a series of Co-based catalysts with alkali metal carbonate promoters were prepared to investigate the interrelation between promotion effect of these carbonates and catalytic performance for aniline hydrogenation to cyclohexylamine in vapour phase. The chemical promoters Li2CO3 and Na2CO3 leading to decrease in catalytic activity of cobalt catalysts for aniline hydrogenation. Catalysts with K2CO3 and Cs2CO3 loadings have practically no catalytic activity for hydrogenation of aniline. Results of TPD of aniline proved that presence of alkali metals carbonates restricts the adsorption of aniline on the surface of cobalt catalysts. Further, it was found that the addition of Na2CO3 greatly enhances the catalytic selectivity towards the cyclohexylamine and inhibits the consecutive reactions of cyclohexylamine leading to formation of by-products such as dicyclohexylamine and N-phenylcyclohexylamine

Fully-Differential Universal Frequency Filter with Dual-Parameter Control of the Pole Frequency and Quality Factor

The paper presents a proposal of modified 2ndorder fully-differential universal frequency filter. Both the pole frequency and quality factor (controlled without disturbing each other) of the filter can be controlled by two independent parameters (i.e. dual-parameter control) in order to increase the range of their control. It is the main improvement in comparison to recent state-of-the-art. The function of the proposed filter has been verified by PSpice simulations and also by experimental measurements

Vascular Remodeling of Clinically Used Patches and Decellularized Pericardial Matrices Recellularized with Autologous or Allogeneic Cells in a Porcine Carotid Artery Model

Background: Cardiovascular surgery is confronted by a lack of suitable materials for patch repair. Acellular animal tissues serve as an abundant source of promising biomaterials. The aim of our study was to explore the bio-integration of decellularized or recellularized pericardial matrices in vivo. Methods: Porcine (allograft) and ovine (heterograft, xenograft) pericardia were decellularized using 1% sodium dodecyl sulfate ((1) Allo-decel and (2) Xeno-decel). We used two cell types for pressure-stimulated recellularization in a bioreactor: autologous adipose tissue-derived stromal cells (ASCs) isolated from subcutaneous fat of pigs ((3) Allo-ASC and (4) Xeno-ASC) and allogeneic Wharton’s jelly mesenchymal stem cells (WJCs) ((5) Allo-WJC and (6) Xeno-WJC). These six experimental patches were implanted in porcine carotid arteries for one month. For comparison, we also implanted six types of control patches, namely, arterial or venous autografts, expanded polytetrafluoroethylene (ePTFE Propaten® Gore®), polyethylene terephthalate (PET Vascutek®), chemically stabilized bovine pericardium (XenoSure®), and detoxified porcine pericardium (BioIntegral® NoReact®). The grafts were evaluated through the use of flowmetry, angiography, and histological examination. Results: All grafts were well-integrated and patent with no signs of thrombosis, stenosis, or aneurysm. A histological analysis revealed that the arterial autograft resembled a native artery. All other control and experimental patches developed neo-adventitial inflammation (NAI) and neo-intimal hyperplasia (NIH), and the endothelial lining was present. NAI and NIH were most prominent on XenoSure® and Xeno-decel and least prominent on NoReact®. In xenografts, the degree of NIH developed in the following order: Xeno-decel > Xeno-ASC > Xeno-WJC. NAI and patch resorption increased in Allo-ASC and Xeno-ASC and decreased in Allo-WJC and Xeno-WJC. Conclusions: In our setting, pre-implant seeding with ASC or WJC had a modest impact on vascular patch remodeling. However, ASC increased the neo-adventitial inflammatory reaction and patch resorption, suggesting accelerated remodeling. WJC mitigated this response, as well as neo-intimal hyperplasia on xenografts, suggesting immunomodulatory properties