Study of degradation processes of Inconel 600 alloy thermocouple shells

Tato diplomová práce se zabývá studiem degradačních procesů pláště termočlánků ze slitiny Inconel 600. Sledovanými degradačními procesy byly mikrostrukturní změny po vysokoteplotní exploataci a jejich vliv na korozní odolnost. Vzorky byly vystaveny teplotě 760 °C po dobu 1 h, 3 h a 7 h. Mikrostruktura a korozní odolnost těchto vzorků byla porovnána se vzorkem ve výchozím stavu. Korozní odolnost byla stanovena pomocí Streicher-testu a zkoušky DL-EPR. Studium mikrostruktury odhalilo, že tepelné zpracování vedlo k postupné precipitaci Cr karbidů podél hranic zrn, což vede ke zcitlivění materiálu, a tedy zvýšení náchylnosti k interkrystalické korozi. Tento předpoklad však výsledky Streicher-testu zcela nepotvrdily. Jak se ukázalo, měla na zjištěné výsledky vliv oxidická vrstva, která se tvořila na povrchu testovaných vzorků v průběhu tepelného zpracování. Zcitlivění vzorků po tepelném zpracování bylo následně prokázáno pomocí testu dle DL-EPR.This thesis deals with the study of degradation processes of thermocouple shells made of Inconel 600 alloy. The observed degradation processes were microstructural changes after high-temperature exploitation and their influence on corrosion resistance. The specimens were exposed to 760 °C for 1 h, 3 h and 7 h. The microstructure and corrosion resistance of these specimens were compared with the specimen in the initial state. The corrosion resistance was determined using the Streicher test and the DL-EPR test. Microstructural studies revealed that heat treatment led to a gradual precipitation of Cr carbides along grain boundaries, which leads to a desensitization of the material and thus an increase in susceptibility to intergranular corrosion. However, this assumption was not fully confirmed by the results of the Streicher test. As it turned out, the results were influenced by the oxide layer that formed on the surface of the tested samples during heat treatment. The sensitisation of the samples after heat treatment was subsequently demonstrated by the DL-EPR test.653 - Katedra materiálového inženýrství a recyklacevýborn

Corrosion resistance of steel sheets with selected coatings

Tato práce se zabývá zjištěním korozní odolnosti ocelových plechů z nízkouhlíkové oceli opatřených nátěrem. Jeden druh vzorků obsahoval navíc povlak zinku mezi nátěrem a kovem. Pro nátěry byly použity práškové barvy RAL 9003, RAL9003S, RAL9005 a RAL9016. U všech vzorků byla nejprve stanovena tloušťka nanesených nátěrů a poté byly provedeny zkoušky korozní odolnosti. Ty zahrnovaly zkoušku odolnosti proti vlhkosti a zkoušku solnou mlhou, kterou byly určen stupeň prorezavění a podrezavění, hmotnostní přírůstek, přilnavost a delaminace nátěrů. Z experimentu vyplynulo, že pro každý druh ocelového plechu, byla nejvhodnější jiná nátěrová hmota. U plechů bez vrstvy zinku se jednalo o práškovou barvu RAL9003 a u plechů opatřených zinkovou vrstvou byla nejvhodnější barva RAL9003S. Celkově nejlépe hodnocený nátěr pro použití na obou typech plechů byla prášková barva RAL9003. Naopak nejhorší výsledky v rámci korozní odolnosti vykázala barva RAL9016, a to u obou typů ocelových plechů.This thesis deals with determining the corrosion resistence of coated low-carbon steel sheets. One type of steel sheet was additionally coated with a layer of zinc. Each of these materials was coated with four different coatings. The coatings used were RAL9003, RAL9003S, RAL9005, RAL9016. First, the thicknesses of the applied coatings were measured for each sample. The samples were then subjected to corrosion resistance tests. These tests included a moisture resistance test and a salt spray test. The latter test determined the degree of corrosion, the degree of undercutting, the weiht gain, the adhesion and the delamination of the coatings. From the performed tests it was evident that each type of steel sheet had the best results with a different coating. The best corrosion resistance of the samples without presence of zinc layer was achieved with RAL9003. The samples with zinc layer achieved the best results with the RAL9003S. Overall, the best rated coating was RAL9003. On the contrary, the RAL9016 provided the worst corrosion resistance for both types of steel. This coating was therefore rated as the worst.636 - Katedra materiálového inženýrstvívýborn

12-O-Tetradecanoylphorbol-13-acetate increases cardiomyogenesis through PKC/ERK signaling

12-O-Tetradecanoylphorbol-13-acetate (TPA) is the most widely used diacylglycerol (DAG) mimetic agent and inducer of protein kinase C (PKC)-mediated cellular response in biomedical studies. TPA has been proposed as a pluripotent cell differentiation factor, but results obtained have been inconsistent. In the present study we show that TPA can be applied as a cardiomyogenesis-promoting factor for the differentiation of mouse embryonic stem (mES) cells in vitro. The mechanism of TPA action is mediated by the induction of extracellular signal-regulated kinase (ERK) activity and the subsequent phosphorylation of GATA4 transcription factor. Interestingly, general mitogens (FGF, EGF, VEGF and serum) or canonical WNT signalling did not mimic the effect of TPA. Moreover, on the basis of our results, we postulate that a TPA-sensitive population of cardiac progenitor cells exists at a certain time point (after days 6–8 of the differentiation protocol) and that the proposed treatment can be used to increase the multiplication of ES cell-derived cardiomyocytes. © 2020, The Author(s).Czech Science FoundationGrant Agency of the Czech Republic [18-18235S]; Faculty of Science of Masaryk University [MUNI/A/1145/2017]; Ministry of Education, Youth and Sports of the Czech Republic (MEYS CR) [LQ1605

Apocynin and Diphenyleneiodonium Induce Oxidative Stress and Modulate PI3K/Akt and MAPK/Erk Activity in Mouse Embryonic Stem Cells

Reactive oxygen species (ROS) are important regulators of cellular functions. In embryonic stem cells, ROS are suggested to influence differentiation status. Regulated ROS formation is catalyzed primarily by NADPH-dependent oxidases (NOXs). Apocynin and diphenyleneiodonium are frequently used inhibitors of NOXs; however, both exhibit uncharacterized effects not related to NOXs inhibition. Interestingly, in our model of mouse embryonic stem cells we demonstrate low expression of NOXs. Therefore we aimed to clarify potential side effects of these drugs. Both apocynin and diphenyleneiodonium impaired proliferation of cells. Surprisingly, we observed prooxidant activity of these drugs determined by hydroethidine. Further, we revealed that apocynin inhibits PI3K/Akt pathway with its downstream transcriptional factor Nanog. Opposite to this, apocynin augmented activity of canonical Wnt signaling. On the contrary, diphenyleneiodonium activated both PI3K/Akt and Erk signaling pathways without affecting Wnt. Our data indicates limits and possible unexpected interactions of NOXs inhibitors with intracellular signaling pathways

Hypoxia Downregulates MAPK/ERK but Not STAT3 Signaling in ROS-Dependent and HIF-1-Independent Manners in Mouse Embryonic Stem Cells

Hypoxia is involved in the regulation of stem cell fate, and hypoxia-inducible factor 1 (HIF-1) is the master regulator of hypoxic response. Here, we focus on the effect of hypoxia on intracellular signaling pathways responsible for mouse embryonic stem (ES) cell maintenance. We employed wild-type and HIF-1α-deficient ES cells to investigate hypoxic response in the ERK, Akt, and STAT3 pathways. Cultivation in 1% O2 for 24 h resulted in the strong dephosphorylation of ERK and its upstream kinases and to a lesser extent of Akt in an HIF-1-independent manner, while STAT3 phosphorylation remained unaffected. Downregulation of ERK could not be mimicked either by pharmacologically induced hypoxia or by the overexpression. Dual-specificity phosphatases (DUSP) 1, 5, and 6 are hypoxia-sensitive MAPK-specific phosphatases involved in ERK downregulation, and protein phosphatase 2A (PP2A) regulates both ERK and Akt. However, combining multiple approaches, we revealed the limited significance of DUSPs and PP2A in the hypoxia-mediated attenuation of ERK signaling. Interestingly, we observed a decreased reactive oxygen species (ROS) level in hypoxia and a similar phosphorylation pattern for ERK when the cells were supplemented with glutathione. Therefore, we suggest a potential role for the ROS-dependent attenuation of ERK signaling in hypoxia, without the involvement of HIF-1

Dynamic Monitoring of Cellular Remodeling Induced by the Transforming Growth Factor-β1

The plasticity of differentiated adult cells could have a great therapeutic potential, but at the same time, it is characteristic of progression of serious pathological states such as cancer and fibrosis. In this study, we report on the application of a real-time noninvasive system for dynamic monitoring of cellular plasticity. Analysis of the cell impedance profile recorded as cell index using a real-time cell analyzer revealed its significant increase after the treatment of prostate epithelial cells with the transforming growth factor-β1. Changes in the cell index profile were paralleled with cytoskeleton rebuilding and induction of epithelial–mesenchymal transition and negatively correlated with cell proliferation. This novel application of such approach demonstrated a great potential of the impedance-based system for noninvasive and real-time monitoring of cellular fate

Modulation of metabolic activity of phagocytes by antihistamines

The purpose of the study was to investigate the effects of H1-antihistamines of the 1st generation (antazoline, bromadryl, brompheniramine, dithiaden, cyclizine, chlorcyclizine, chlorpheniramine, clemastine) and the 2nd generation (acrivastine, ketotifen, and loratadine) on the respiratory burst of phagocytes. Reactive oxygen species generation in neutrophils isolated from rat blood was measured using luminol-enhanced chemiluminescence. Changes in nitrite formation and iNOS protein expression by RAW 264.7 macrophages were analysed using Griess reaction and Western blotting. The antioxidative properties of drugs in cell-free systems were detected spectrophotometrically, luminometrically, fluorimetrically, and amperometrically. The majority of the H1-antihistamines tested (bromadryl, brompheniramine, chlorcyclizine, chlorpheniramine, clemastine, dithiaden, and ketotifen) exhibited a significant inhibitory effect on the chemiluminescence activity of phagocytes. H1-antihistamines did not show significant scavenging properties against superoxide anion and hydroxyl radical, thus this could not contribute to the inhibition of chemiluminescence. H1-antihistamines had a different ability to modulate nitric oxide production by LPS-stimulated macrophages. Bromadryl, clemastine, and dithiaden were the most effective since they inhibited iNOS expression, which was followed by a significant reduction in nitrite levels. H1-antihistamines had no scavenging activity against nitric oxide. It can be concluded that the effects observed in the H1-antihistamines tested are not mediated exclusively via H1-receptor pathway or by direct antioxidative properties. Based on our results, antihistamines not interfering with the microbicidal mechanisms of leukocytes (antazoline, acrivastine and cyclizine) could be used preferentially in infections. Other antihistamines should be used, under pathological conditions accompanied by the overproduction of reactive oxygen species

Analysis of information security in selected municipalities

The aim of this work is to analyze information and communication technologies in selected municipalities using security standards, especially ISO / IEC 27000. The work focuses mainly on the state of cyber security and the impact of GDPR regulation on systems in municipalities and relevant processes. A questionnaire survey of these impacts was carried out and possible measures were proposed on the basis of the analysis of the questionnaires and the carried-out risk analysis. It was found that there is no dependence between the financial demands of GDPR implementation and the type of municipality. There is also no dependence between the time required to implement GDPR and the type of municipality. There is no dependence between whether the municipality has a security policy document and whether it carries out a risk analysis. Furthermore, there is a dependence between whether the municipality has an information system and how time-consuming was the implementation of GDPR into the municipality's processes. The level of cyber security varies significantly from municipality to municipality. The GDPR General Regulation has had some impact on cyber security and processes in individual municipalities, but in many cases on a theoretical rather than a practical level. In addition, the complexity of laws and standards does not help to improve the state of cyber security