Machining of ceramic bodies using CAD-CAM

Bakalářská práce se v literární části zabývá keramickými materiály na bázi Al2O3 a ZrO2, metodami přípravy vzorků pro následné obrábění, metodami obrábění keramiky, a to především technologií CNC frézovaní v neslinutém a slinutém stavu s jejich porovnáním. V práci jsou uvedeny možné příklady použití keramických dílů. Experimentální část práce se zabývá obrobením keramiky na bázi ZrO2 za použití různých druhů prášku, metody přípravy a volbou slinovací teploty v návaznosti na její vlastnosti. Nejlepších výsledků dosáhl materiál SZ-3Y slinovaný při teplotě 1550 °C po dobu 2 hodin, hodnoty pevnosti zde byly 1203 MPa, drsnost Ra 126 nm, velikost zrna 382 nm.The literature part of bachelor's thesis deals with ceramic materials based on Al2O3 and ZrO2, methods of sample preparation for consequent machining, different methods of machining, especially the technology of CNC machining in non-sintered and sintered state with their comparison. The thesis presents possible examples of the use of ceramic parts. The experimental part of the thesis deals with the machining of ceramic based on ZrO2 using different types of ceramic powders, methods of preparation and the choice of the sintered temperature in relation to its properties. The best results were achieved with SZ-3Y ceramic material sintered at 1550 °C for 2 hours, strength values were 1203 MPa, roughness of surface Ra was 126 nm a grain size was 382 nm.

Foliar selenium biofortification of soybean: the potential for transformation of mineral selenium into organic forms

IntroductionSelenium (Se) deficiency, stemming from malnutrition in humans and animals, has the potential to disrupt many vital physiological processes, particularly those reliant on specific selenoproteins. Agronomic biofortification of crops through the application of Se-containing sprays provides an efficient method to enhance the Se content in the harvested biomass. An optimal candidate for systematic enrichment, guaranteeing a broad trophic impact, must meet several criteria: (i) efficient accumulation of Se without compromising crop yield, (ii) effective conversion of mineral Se fertilizer into usable organically bound Se forms (Seorg), (iii) acceptance of a Se-enriched crop as livestock feed, and (iv), interest from the food processing industry in utilization of Se-enriched outputs. Hence, priority should be given to high-protein leafy crops, such as soybean.MethodsA three-year study in the Czech Republic was conducted to investigate the response of field-grown soybean plants to foliar application of Na2SeO4 solutions (0, 15, 40, and 100 g/ha Se); measured outcomes included crop yield, Se distribution in aboveground biomass, and the chemical speciation of Se in seeds.Results and DiscussionSeed yield was unaffected by applied SeO42-, with Se content reaching levels as high as 16.2 mg/kg. The relationship between SeO42-dose and Se content in seeds followed a linear regression model. Notably, the soybeans demonstrated an impressive 73% average recovery of Se in seeds. Selenomethionine was identified as the predominant species of Se in enzymatic hydrolysates of soybean, constituting up to 95% of Seorg in seeds. Minor Se species, such as selenocystine, selenite, and selenate, were also detected. The timing of Se spraying influenced both plant SeO42- biotransformation and total content in seeds, emphasizing the critical importance of optimizing the biofortification protocol. Future research should explore the economic viability, long-term ecological sustainability, and the broad nutritional implications of incorporating Se-enriched soybeans into food for humans and animals

Processing of compact polycrystalline YAG ceramics

V literární části této diplomové práce byla provedena rešerše na různé metody přípravy hutné polykrystalické YAG keramiky a vlivů slinování na zhutnění a další požadované vlastnosti takto připravené YAG keramiky, řešena byla také transparentnost po přidání dopujících prvků. V experimentální části diplomové práce byly připravené vzorky hutné polykrystalické YAG keramiky pomocí metody SSR a byl studován vliv slinování na zhutnění a pórovitost keramických YAG vzorků. Na slinovaných vzorcích byla měřena jejich relativní hustota, pórovitost, fázová čistota a transparentnost. Tyto naměřené hodnoty byly porovnány s výsledky prací uvedených v literární části.In the literary part of this master thesis a research on various methods of preparation of dense polycrystalline YAG ceramics and the effects of sintering on the densification and other desired properties of such prepared YAG ceramics was carried out, the transparency after addition of dopant elements was also discussed. In the experimental part of the thesis, samples of dense polycrystalline YAG ceramics were prepared by SSR method and the effect of sintering on the densification and porosity of the YAG ceramic samples was studied. Relative density, porosity, phase purity and transparency were measured on the sintered samples. These measurements were compared with the results of the works reported in the literature section.

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Katedra severoamerických studiíDepartment of North American StudiesFaculty of Social SciencesFakulta sociálních vě

Liability of an Employee for Damage

Katedra pracovního práva a práva sociálního zabezpečeníDepartment of Labor Law and Social Security LawPrávnická fakultaFaculty of La

Processing of compact polycrystalline YAG ceramics

In the literary part of this master thesis a research on various methods of preparation of dense polycrystalline YAG ceramics and the effects of sintering on the densification and other desired properties of such prepared YAG ceramics was carried out, the transparency after addition of dopant elements was also discussed. In the experimental part of the thesis, samples of dense polycrystalline YAG ceramics were prepared by SSR method and the effect of sintering on the densification and porosity of the YAG ceramic samples was studied. Relative density, porosity, phase purity and transparency were measured on the sintered samples. These measurements were compared with the results of the works reported in the literature section

Monitoring, prevention and control of plum moth (BIOFRUITNET Practice Abstract)

Pheromones used for Grapholita funebrana are not species-specific, and usage of pheromone dispenser lures will attract other Grapholita species including Grapholita molesta (Oriental fruit moth), causing similar damage. Practical recommendations • HOST PLANTS: Larvae can cause significant damage on main host plants as plums (Prunus domestica) and apricots (Prunus armeniaca). In addition, peaches (Prunus persica), almonds (Prunus amygdalus) and other Prunus species are also attacked. • LIFE CYCLE: usually two generations per year • 1st generation: May to June • 2nd generation: July to August • In climatically favourable regions, a third generation may emerge around mid-August before the adult caterpillars of the last generation visit the overwintering sites. • DAMAGE: o 1st generation: Female moths lay eggs singly or in small groups on fruitlets. Entrance holes, however, are barely visible. Larval feeding causes gummosis, exuding fluid from the entrance hole. These are good detections for diagnostic observation. A premature colour change from green to violet and/or fruits drop. o 2nd generation: Females lay eggs in maturing fruits, and larvae feed throughout the fruit, travelling from the outer part to the stone region, forming filled tunnels and feeding inside. Usually, only one caterpillar develops per fruit. Fruits are inedible, unmarketable quality. • CONTROL AND PREVENTION: Use mating disruption with the pheromone dispensers Pheromones to monitor G. funebrana can be placed in the same traps with pheromones of Cydia pomonella o Placing sex pheromone dispensers along the edges of fields, rather than in the centre, is recommended o Pheromone traps are not species-specific, catching many other Grapholita species, including males of G. molesta o Late-maturing varieties are more damaged, early ripening varieties should therefore be grown. o Direct control by the application of products based on Bacillus thuringiensis ssp. kurstaki onto the fruits at the peak of larvae hatching

Strategy to control Plum Pox Virus damage (BIOFRUITNET Practice Abstract)

Growing PPV-resistant varieties combined with PPV-resistant rootstocks improve fruit-growing economics and financial return. Practical recommendations • HOST PLANTS: All stone fruit species, PPV mainly infects plum trees. Apricots, peaches, nectarines, and sweet and sour cherries can be infected by different strains of the virus • SYMPTOMS of the Plum Pox Virus disease: o On leaves: Ring-shaped chlorotic spots and marks, mostly diffused, bright green o On fruits: Deformations, ring-, line- or pox-like depressions or shrivelling fruit • DAMAGE: o Fruits have lower sugar content, worse appearance, and are unsuitable for fresh sale consumption o Fruits fall prematurely to the ground, and fruit quality and yield is lower o Infected trees have lower assimilation due to chlorotic spots, and tree vigour is lower DISEASE TRANSMISSION: o PPV damage occurs mainly after planting of infected plant material, and the virus is spread by aphids in orchards o Vegetative, especially by vegetative reproduction (scions, grafts) o PPV can also be spread during tree pruning through non-disinfected pruning devices • PROTECTION: Treatment against PPV does not exist yet, so the application of preventive measures is the only effective way of disease control. Direct control only reduces the next virus spreading o PREVENTIVE MEASURES: Use certified virus-free plant material, and grow resistant varieties grafted onto resistant rootstocks to fully protect trees against PPV infection o DIRECT MEASURES: Destroy all infested trees and control aphids (the vector of PPV transmission) for the purpose of decreasing the additional spreading of PPV within the orchard • PPV-resistant plum varieties: Jojo, Jofela, Joganta, Jolina, and Moni • PPV-resistant plum rootstocks: Docera 6, and Dospina 235 • Growing resistant varieties on resistant rootstocks avoid PPV infections in plum orchard