Study of the possibilities of using nanoiron (nZVI) in removal of metal ions from mine water

Diplomová práce se zabývá problematikou využití nanočástic nulamocného železa (nZVI) pro odstranění vybraných kovů z důlních vod. Teoretická část popisuje důlní vody a jejich rozdělení a vybrané chemické ukazatele. Dále se zaměřuje na popis nulamocného nanoželeza (nZVI), postupy jeho přípravy a modifikace. Experimentální část je rozdělena na několik částí. V první části je řešena aktivace NANOFER STAR nZVI a ověření jeho reaktivity s použitím modelových vod chromu, chloridů a síranů. Další část experimentů ověřuje účinnost nZVI pro odstranění kovů z modelových vod, a to konkrétně zinku, manganu a mědi. V poslední části je ověřována účinnost nZVI pro odstraňování kovů na reálném vzorku důlní vody z lokality Zlaté Hory. Z výsledků lze konstatovat, že účinnost odstranění mědi a zinku z důlní vody je vysoká, tj. u zinku 95 % a mědi prakticky 100 %, u manganu 65 %. Další výsledky a shrnutí poznatků jsou uvedeny v závěru předložené práce.The diploma thesis deals with the use of nanoparticles of zero-valent iron (nZVI) in the removal of selected metals from mine water. The theoretical part describes mine waters, their classification and selected chemical indicators. It also focuses on the description of zero-valent nanoiron (nZVI), procedures of its preparation and modifications. The experimental part is divided into several parts. The first part deals with the activation of NANOFER STAR nZVI and verification of its reactivity using model waters of chromium, chloride and sulfate. The next part of the experiments verifies the effectiveness of nZVI for the removal of metals, specifically zinc, manganese and copper, from model waters. The last part verifies the efficiency of nZVI for metal removal on a real mine water sample from the Zlaté Hory site. From the results it can be concluded that the removal efficiency of copper and zinc from mine water is high, i.e. 95 % for zinc and practically 100 % for copper, and 65 % for manganese. Further results and a summary of the findings are given in the conclusion of the present work.546 - Katedra environmentálního inženýrstvívýborn

The Effect of Simultaneous Si and Ti/Mo Alloying on High-Temperature Strength of Fe3Al-Based Iron Aluminides

The effect of phase composition and morphology on high-temperature strength in the compression of Fe-Al-Si-based iron aluminides manufactured by casting was investigated. The structure and high-temperature strength in the compression of three alloys-Fe28Al5Si, Fe28Al5Si2Mo, and Fe28Al5Si2Ti-were studied. Long-term (at 800 degrees C for 100 h) annealing was performed for the achievement of structural stability. The phase composition and grain size of alloys were primarily described by means of scanning electron microscopy equipped with energy dispersive analysis and Electron Backscatter Diffraction (EBSD). The phase composition was verified by X-ray diffraction (XRD) analysis. The effect of Mo and Ti addition as well as the effect of long-term annealing on high-temperature yield stress in compression were investigated. Both additives-Mo and Ti-affected the yield stress values positively. Long-term annealing of Fe28Al5Si-X iron aluminide alloyed with Mo and Ti deteriorates yield stress values slightly due to grain coarsening

Effect of Higher Silicon Content and Heat Treatment on Structure Evolution and High-Temperature Behaviour of Fe-28Al-15Si-2Mo Alloy

This paper describes the structure and properties of cast Fe3Al-based alloy doped with 15 at. % of silicon and 2 at. % of molybdenum. The higher content of silicon is useful for the enhancement of high-temperature mechanical properties or corrosion resistance of iron aluminides but deteriorates their workability due to increased brittleness. It was found that the presence of both alloying elements leads to an increase of values of the high-temperature yield stress in compression. The heat treatment (annealing at 800 degrees C for 100 h) used for the achievement of phase stability causes the grain coarsening, so the values of the high-temperature yield stress in compression are lower at 600 degrees C and 700 degrees C in comparison to values measured for the as-cast state. This stabilization annealing significantly improves the workability/machinability of alloy. Furthermore, the higher silicon content positively affects the values of the thermal expansion coefficient that was found to be lower in the temperature range up to 600 degrees C compared to alloys with lower content of silicon

Solutions of critical raw materials issues regarding iron-based alloys

The Critical Raw Materials (CRMs) list has been defined based on economic importance and supply risk by the European Commission. This review paper describes two issues regarding critical raw materials: the possibilities of their substitution in iron-based alloys and the use of iron-based alloys instead of other materials in order to save CRMs. This review covers strategies for saving chromium in stainless steel, substitution or lowering the amounts of carbide-forming elements (especially tungsten and vanadium) in tool steel and alternative iron-based CRM-free and low-CRM materials: austempered ductile cast iron, high-temperature alloys based on intermetallics of iron and sintered diamond tools with an iron-containing low-cobalt binder

Modified activities of macrophages’ deubiquitinating enzymes after Francisella infection

Francisella tularensis influences several host molecular/signaling pathways during infection. Ubiquitination and deubiquitination are among the most important regulatory mechanisms and respectively occur through attachment or removal of the ubiquitin molecule. The process is necessary not only to mark molecules for degradation, but also, for example, to the activation of signaling pathways leading to pro-inflammatory host response. Many intracellular pathogens, including Francisella tularensis, have evolved mechanisms of modifying such host immune responses to escape degradation. Here, we describe that F. tularensis interferes with the host’s ubiquitination system. We show increased total activity of deubiquitinating enzymes (DUBs) in human macrophages after infection, while confirm reduced enzymatic activities of two specific DUBs (USP10 and UCH-L5), and demonstrate increased activity of USP25. We further reveal the enrichment of these three enzymes in exosomes derived from F. tularensis-infected cells. The obtained results show the regulatory effect on ubiquitination mechanism in macrophages during F. tularensis infection

INFLUENCE OF AGE, GENDER AND SIRE LINE ON YOUNG CATTLE BEHAVIOUR TRAITS

The aim of this study was to test effects of age, gender, and sire line on dairy cattle behaviour. We have analyzed results of ethological tests for 40 Holstein breed animals (23 males and 17 females), offsprings of three sires. Maintenance behaviour were observed at the age of 90, 130 and 170 days. Behaviour in the maze was conducted at the age of 119 days, an open-field test was applied at the age of 124, 168, and 355 days. The social behaviour was determined by feeding on 155th day of the age. The times and the number of periods in all activities of maintenance behaviour were changing significantly (P<0.001) according to the age. The total time of lying, lying with ruminating, ruminating, feeding was increasing from the age of 90 days to the age of 170 days, on the other hand the time of standing was decreasing. The times of total lying, lying with ruminating, total ruminating, feeding were increased, and time of standing was decreased from the age of 90 days to the age of 170 days. Calves spent more time lying on the left side than on the right side. The number of ruminating periods was increasing according to the age. Eating periods were decreasing from the age of 90 to 170 days. The most of lying periods were recorded at the age of 130 days. The differences between sex were found in total time of lying, lying on the right side (P<0.05), and the males rest longer and had more periods of lying than females. We have found differences in times of feeding (P<0.001), total lying, standing (P<0.01), and lying on the left side (P<0.05) according to sire by comparing behaviour of the calves. Sire genotypes were significantly manifested in period number of total lying (P<0.001), lying on the right side, feeding (P<0.01), and standing (P<0.05). Males stood in the first part of maze longer than females (P<0.001), also length of total standing was longer by bulls (P<0.01). Heifers took shorter time to leave the maze than bulls (P<0.05). Sire lineages significantly differed in times of standing in the first part of maze and maze leaving. We did not find any significant differences either among sire lineage groups or between genders in locomotor behaviour measured by the number of crossed squares in open-field test. During all observations were more mobile heifers. No significant differences were found between males and females in social behaviour. The sire line influenced only the number of total duels (P<0.001). We found significant positive relationship between live body weight and time of staying in the first part of maze (r=0.3957**), time of maze leaving (r=0.3720**), and number of total and win duels (0.4031**, 0.3216*). Significant relationships were recorded in almost maintenance behaviour activities (P<0.001). Consistency of locomotor behaviour was proved only between the ages of 124 and 168 days (r=0.3177*). Significant relationship between maze behaviours and number of crossed squares were found only in ages of 119 and 124 days (r=-0.3721**; r=- 0.4110**; r=-0.3994**)

The 2018 European heatwave led to stem dehydration but not to consistent growth reductions in forests

Heatwaves exert disproportionately strong and sometimes irreversible impacts on forest ecosystems. These impacts remain poorly understood at the tree and species level and across large spatial scales. Here, we investigate the effects of the record-breaking 2018 European heatwave on tree growth and tree water status using a collection of high-temporal resolution dendrometer data from 21 species across 53 sites. Relative to the two preceding years, annual stem growth was not consistently reduced by the 2018 heatwave but stems experienced twice the temporary shrinkage due to depletion of water reserves. Conifer species were less capable of rehydrating overnight than broadleaves across gradients of soil and atmospheric drought, suggesting less resilience toward transient stress. In particular, Norway spruce and Scots pine experienced extensive stem dehydration. Our high-resolution dendrometer network was suitable to disentangle the effects of a severe heatwave on tree growth and desiccation at large-spatial scales in situ, and provided insights on which species may be more vulnerable to climate extremes

Water clarification - preparation of an experiment for a teaching module

Bakalářská práce je zaměřena na přípravu experimentu pro výukový modul, který demonstruje koagulaci a flokulaci. Teoretická část popisuje vlastnosti vod a jejich složení. Je zaměřena na koloidní částice a jejich odstraňování pomocí číření. V praktické části je popsána příprava modelové vody z rašelinového koncentrátu. V této vodě bylo laboratorně provedeno číření, a to přidáním koagulantů síranu hlinitého nebo chloridu železitého a flokulantu Sokoflok 53. V laboratoři bylo ověřeno, že zvolená činidla dokážou odstranit zákal a snížit CHSKMn, a to v případě síranu hlinitého o 39 % a při použití chloridu železitého o 46 %. Výsledkem bakalářské práce je návrh přípravy modelové vody a vhodných čiřicích činidel a jejich dávek tak, aby bylo možné experiment reprodukovat a použít pro přípravu laboratorní úlohy na výukovém modulu.The Bachelor thesis is focused on the preparation of a teaching module experiment which demonstrates coagulation and flocculation. The theoretical part describes water properties and its composition, with a focus on colloidal particles and their removal by clarification. The practical part describes the preparation of model water from peat concentrate. This water was subjected to laboratory clarification by adding coagulants, namely aluminium sulphate or ferric chloride, and flocculant Sokoflok 53. In the laboratory conditions, it has been verified that the selected reagents are able to remove turbidity and reduce CODMn;, in case of aluminium sulphate by 39 % and using ferric chloride by 46 %. The result of the Bachelor thesis is a proposal of preparation of model water and suitable clarifying reagents and their doses so that the experiment can be reproduced and used for the preparation of students’ laboratory tasks on the teaching module.546 - Katedra environmentálního inženýrstvívýborn