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Influence of cement moulds on the structure of nodular iron castings
Stachovec, Ivo ; Šenberger, Jaroslav (referee) ; Rusín, Karel (advisor)
The object of the diploma thesis was to solve and to describe the influence of cement sands moulds on the structure of castings with cast iron LKG. The work was intent on watching the tendency of cement sands to the metal penetration of castings, rising of the compounds on the metal mould interface and liquid metal and accompanies elements on the shape of the graphite in the surface of casting. The study of this processes has a big theoretical and a practical meaning, for prevent and prediction of rising of the defects that are attached with unsuitable choice of sand.
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Transport of humic substances through plant cuticle
Hývnarová, Lucie ; Kalina, Michal (referee) ; Klučáková, Martina (advisor)
In my bachelor thesis I deal with the transport of lignohumate through the plant cuticle. Specifically, I deal with transport through the leaf cuticle, which is divided into upper and lower cuticles. The difference between the upper and lower cuticles is that the lower cuticle contains vents. To study this transport, it was first necessary to separate the cuticles from the leaf. I used two methods of chemical isolation, which is more aggressive, but it is less time consuming (3 days) and a chemical method that is softer but takes longer (about 6 weeks). I created diffuse vapors from the separated cuticles, which consist of a source gel, where the lignohumate agarose gel and the intake gel are purely agarose gel. In these diffuse pairs, the time profile of the concentration profiles was monitored by UV-VIS spectrometry for 10 days and diffusion of the source gel into the uptake gel was monitored. Based on Fick's laws and their solution for diffusion in a pair of infinite media, the diffusion coefficient of lignohumate in the hydrogel was determined and the effect of isolated cuticles as a barrier at the interface between the two hydrogels was assessed. The results show that lignohumate diffuses best through the lower cuticle, which was separated by a chemical isolation method. Chemical isolation is much more drastic than the enzymatic method because zinc chloride is used, which is corrosive and damages cellulose. Thus, in this isolation, the cuticle structure is damaged and thereby reduced, resulting in increased membrane permeability.
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Vliv teploty lepidla a povrchu adherendu na hloubku penetrace lepidla do masivního dřeva
Voldřichová, Anna
The final thesis deals with the influence of different gluing conditions on the depth of penetration of the adhesive into the surface of solid wood, specifically of the influence of increased pressure during pressing. Furthermore, the thesis investigates the effect of penetration on the strength of the glued joint under tensile loading. Specimens of spruce and oak wood were glued with UF glue and PVAC glue, pressed under different compression pressures and then subjected to tensile test. SEM analysis on an electron microscope was used to evaluate the depth of penetration. The results of the investigation of the effect of ink on the strength of the bonded joint and the penetration depth of the adhesive into the material are also included. The ink was used in the adhesive mixtures for the purpose of colouring the bonded joint.
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Texturní a barevné vlastnosti sýrů ošetřených extracelulárními enzymy
Jašková, Jana
This diploma thesis deals with textural and color properties of cheeses treated with an extracellular enzyme. The cheese samples were matured for three weeks. The penetration and compression method was used to determine the textural properties of the cheeses. The color of the cheeses was measured on a CM 3500d spectrophotometer. The lowest strength determined by the penetration method had the sample with laccase after production (0.55 ± 0.07 N) and the highest strength had the control sample, which was aged for one week (1.31 ± 0.14 N). The lowest strength determined by the compression method had the sample with laccase, which had matured for two weeks (3.11 ± 1.07 N) and the highest strength had the control sample of cheese matured for three weeks (12.28 ± 2.36 N). The values of L*(D65) varied for all samples in the range from 72.89 ± 0.31 to 87.76 ± 0.01, the values of a*(D65) from -1.95 ± 0.01 to 0.66 ± 0.05 and b*(D65) values were measured between 6.73 ± 0.35 and 20.93 ± 0.03 Laccase enzyme treatment had no significant effect on the firmness and color of the cheese samples.
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Influence of sand size of core mixtures on surface quality of cast iron castings
Brůža, František ; Krutiš, Vladimír (referee) ; Záděra, Antonín (advisor)
The diploma project deals with the mechanisms of burn-on casting defects on castings made of spheroidal graphite cast iron. It discusses the elimination of their occurrence in the conditions of the German foundry MAT Ueckermünde by changing the granulometry of the core sand. Subsequently, the thesis deals with the influence of this change on the greensand. Furthermore, the thesis compares three refractory coatings supplied by the foundry. The coatings are compared both by laboratory measurements and by experimental tests during casting in conditions simulating the operation of this foundry. Finally, the individual tests are evaluated, including the effect of the individual measures in the case of their use in MAT Ueckermünde.
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Glycocalyx shedding by cercariae of bird schistosomes
Chaloupecká, Jana ; Mikeš, Libor (advisor) ; Štěrba, Ján (referee)
Trichobilharzia spp. are avian schistosomes related to medically important human parasites of the genus Schistosoma. Penetrating cercariae are well known as causative agent of cercarial dermatitis in humans. Cercariae actively penetrate the skin of definitive hosts and transform into schistosomula. This process is preceded by cercarial tail detachment and includes emptying of penetration glands and extensive surface changes. One of these changes is the loss of highly immunogenic glycocalyx which represents a protective coat in the aquatic environment. The glycocalyx has specific composition of saccharide molecules which are bound to lipids or proteins on the membrane of cercarial tegument. There is only limited information about the mechanism of shedding. Hypotheses based on indirect evidences suggest that peptidases or (phospho)lipases from penetration glands could be involved. This work describes the changes in surface glycosylation during transformation of cercariae into schistosomula by fluorescently labelled lectins and monoclonal antibodies against Lewis X antigen. Lectins UEA-I, LTA and PNA have been chosen as markers of transformation of T. regenti. Further, our experiments have been focused on shedding of cercarial glycocalyx. During in vitro induction of penetration gland emptying and...
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Cathepsins L of Diplostomum pseudospathaceum cercariae
Perháčová, Terézia ; Mikeš, Libor (advisor) ; Hartmann, David (referee)
This study is focused on cercarial cysteine peptidases of the trematode Diplostomum pseudospathaceum. It follows previous research which confirmed the presence of a 24kDa cysteine peptidase in cercariae biochemically and by mass spectrometry. It was postulated, that the function of this peptidase is histolytic, when cercariae penetrate the tissues. During an attempt to purify this peptidase and characterize its peptidolytic activity, it was found out that the cercarial homogenate containsmore different peptidases varying in their pI. Tests of peptidolytic activity and inhibition have shown that these peptidases are cathepsin L-like. They are active over a broad spectrum of pH with optima of activities in weakly acidicor neutral pH. Using degenerate primers based on conserved motifs of cysteine pepridases, partial sequences of three genes for cathepsin L of D. pseudospataceum (DpCL1, 2 a 3) were obtained. Then the complete sequences of DpCL2 and 3 genes and partial sequence (without 5'end) of DpCL1 were obtained by RACE PCR. To confirm function of these peptidases we tried to immunolocalize them. We assumed that they are localized in penetration glands. Preliminary results suggested that some of the cathepsins could be also localized in the gut of cercariae. For more detailed biochemical...
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Morphological and functional variability of secretory glands in cercariae of chosen trematode groups
Krčmářová, Veronika ; Bulantová, Jana (advisor) ; Mikeš, Libor (referee)
Trematodes are characterized by their complex life cycles that include definitive hosts and variable number of intermediate hosts. Transfer of the parasite from the first intermediate host to the other is usually realized by larval stage called cercaria. After finishing of their development within the first intermediate host, morphology and fate of these larval stages vary according to the way of infection of the next host. Some cercariae actively penetrate directly to their definitive hosts trough their body surface, other encystate in the outer environment where they wait in a form of metacercariae to be ingested by definitive host. Both of these ways can be combinated and cercariae encystate inside second intermediate host after they actively penetrate them. Exceptionally, cercariae do not leave the sporocyst in which they were developing inside the first intermediate host. They encyst there waiting for ingestion by the definitive host. Various types of secretory glands have been developed in cercariae for successful direct infection of next hosts, survival of parasite in adverse conditions of outer environment or for transformation of one larval stage to subsequent one. Variability in morphology and function of these secretory glands in cercariae is closely connected with differences in life...
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Usage of fast-reacting SBS polymer in the production of asphalt mixtures
Dohnálek, Jakub ; Dašek, Ondřej (referee) ; Hýzl, Petr (advisor)
The subject of this diploma thesis is a research of bituminous binder modification by fast react-ing polymer SBS. The theoretical part covers an introduction to bituminous binders, their pro-duction, chemical and physical-mechanical properties. The identification of bituminous binders and their use in bituminous mixtures is briefly described. To conclude, current modification methods are described in detail and important modifiers are introduced. In the practical part, three applied tests (softening point, elastic recovery and penetration) are described in detail. The bituminous binders tested (20/30, 30/45, 70/100, PMB 25/55-55 and PMB 45/80-50) and the fast-reacting polymer SBS are introduced. Samples with two weight percentages of SBS, 7,5% and 10%, are produced. Two mixing times, 60 seconds and 600 seconds were used to mix the bituminous binder and SBS. In conclusion, the results are evaluated and commented. Further research suggestions regarding this field are recommended.
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Změny texturních vlastností hovězího masa v průběhu zrání
Hermanová, Nikola
This diploma thesis is focused on textural properties of beef meat during aging. Round and sirloin from three heifers of Czech Fleckvieh breed were used for the experiment. Samples were analyzed by Warner-Bratzler test, compression test and penetration test in 4th, 6th, 7th and 8th week of aging. Results of Warner-Bratzler test ranged from 54,72 – 59,96 N and there was not found statistically significant difference. Results from compression test TPA1 were in range 187,75 – 277,05 N and TPA2 results were in range 153,74 – 225,55 N and there was found statistically highly significant difference in most cases. Penetration test results of beef round were in range 5,58 – 6,18 N and there was not found statistically significant difference. Penetration test results of beef sirloin were in range 6,39 – 9,49 N and the difference was not statistically significant in most cases.
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