National Repository of Grey Literature 101 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Problems of the complex potentials of the isotropic elasticity
Kubíček, Radek ; Hrstka, Miroslav (referee) ; Profant, Tomáš (advisor)
The presented diploma thesis concerns linear fracture mechanics and deals with determination of the stress intensity factor of the finite crack, which is located in the vicinity of the bimaterial interface, solved by the distributed dislocation technique and theory of complex potencials. The work is possible to devide into three parts. The first part includes basic concepts of the linear fracture mechanics and is also dedicated to the mechanics of composite materials. The second part deals with the determination of the stress intensity factor from solving singular integral equation formulated by Bueckner's principle and the distributed dislocation technique. The third part includes the specific configuration of the crack with respect to the bimaterial interface and the solution, which is compared with results obtained from the FE analysis.
The basic chemical parameters of several varieties of sour cherries
Komárek, Šimon ; Vítová, Eva (referee) ; Hrstka, Miroslav (advisor)
This bachelor thesis deals with determination of basic chemical parameters in sour cherry (Prunus cerasus). Three different cultivars Köröšská, Pandy 6039 and Šumadinka were examined. The content of total solids varied from 13,32 to 15,22 %, soluble solid content amounted for 12,04–14,60 %, ash 0,4 %, reducing sugars 4,9–6,9 %, nitrogenous substances 0,11–0,12 %, L-ascorbic acid 343–456 mg/kg. Titratable acidity ranged from 15,1 to 21,8 g malic acid equivalent/kg, formol number 268–373 ml of 0,1 NaOH/kg. Total anthocyanins varied from 308 to 1104 mg cyanidin 3-glucoside equivalent/kg and total phenolics ranged from 1,05 to 3,99 g gallic acid equivalent/kg. All data are applied to fresh fruit weight.
The basic chemical parameters of several varieties of cherries
Boberová, Jana ; Vespalcová, Milena (referee) ; Hrstka, Miroslav (advisor)
This bachelor thesis deals with determination of basic chemical parameters in sweet cherry (Prunus avium). In the theoretical part, the taxonomic classification of the cherry, its botanical characteristics and the pomology of several cultivars are mentioned. Also, the history of cultivation, appropriate conditions and most common diseases are listed. The last chapter deals with the chemical composition of the fruits. In the experimental part, the determination of selected chemical parameters of various cultivars (Karešova, Napoleonova and Stark Gold) were determined. The content of total solids was determined in the range of 14.53–18.15 %, soluble solids 13.96–16.44 %, ash 0.34–0.44 %, reducing sugars 6.89–10.18 % and nitrogenous substances 0.056–0.116 %. Ascorbic acid content was set at 26.1–44.1 mg/kg. The titratable acidity was determined in the range of 6.15–8.86 g of predominant malic acid in 1 kg of cherry and a formol number was determined from 194 to 297 ml of 0.1 M NaOH per 1 kg of edible fraction. The amount of anthocyanins was determined at 4–686 mg cyanidin-3-rutinoside/kg and total phenolic compounds at 0.91–1.47 g gallic acid/kg. All data are based on fresh fruit weight.
Impact of temperature and drought on gliadins content in two varieties of wheat
Seidlová, Kateřina ; Brázda, Václav (referee) ; Hrstka, Miroslav (advisor)
This bachelor’s thesis focuses on the effect of high temperature and drought on protein content of gliadin fraction on two varieties of wheat. Chosen varieties were Hyfi and Julie, cultivated at 26, 29, 32, 35 and 38 °C during flowering in watering controlled conditions. The condition for ‘wet’ samples was at least 70 % soil moisture and for ‘dry’ samples less than 30 % soil moisture. After harvesting, the seeds were milled into flour from which the gliadins were extracted with 2-chlorethanol. A-PAGE method was used for gliadin separation, quantification was carried out through computer densitometry. A significant genotype effect was discovered. Whilst temperature ranging from 26-38 °C with simultaneous drought stress had no significant effect on gliadin content of Hyfi variation, gliadin content of Julie variation shown obvious maximum at 32 °C. Therefore, Hyfi variation shown better resistance to heat stress than Julie variation. Both variations had higher gliadin content under drought stress than under good watering conditions.
Impact of nitrogen fertilization and drought on glutenins content in winter wheat
Vostrejš, Pavel ; Vítová, Eva (referee) ; Hrstka, Miroslav (advisor)
In this bachelor thesis the effects of nitrogen fertilization and drought stress on glutenin fraction of winter wheat (Triticum aestitivum L.) were studied. Winter wheat cultivar Tiguan was grown under different rainfall mode, on the one hand in drought (DRY), on the other hand in normal downfall (WET). Part of the samples was treated with nitrogen fertilization at a dose of 140 kg / ha (N140), the other part remained without fertilization (N0). After the gliadins were separated, the glutenins from the samples were extracted with 50% isopropanol with 1% DTT. Individual glutenin fractions were separated by SDS-PAGE and quantified by computer densitometry. The drought did not have a statistically significant effect on any of the glutenin subunits. Nitrogen fertilization caused an increase in the total amount of glutenin as well as the amount of individual subunits. Interaction of water regime treatment and fertilization has not led to an increase in glutenin levels in HMW 3 GS and LMW 5 GS in DRY conditions.
The content of aroma active compounds in sweets
Paulišová, Sabina ; Hrstka, Miroslav (referee) ; Vítová, Eva (advisor)
This bachelor thesis focuses on identification of aroma active compounds in selected samples of non-chocolate sweets. Based on the results obtained, the aromatic profile of the individual samples is compared. The theoretical part deals with aroma active compounds, legislation and technology of manufacturing non-chocolate sweets. Further experimental technique and the methods used in practical part, namely solid phase microextraction and gas chromatography with mass spectrometry detection are presented. In the experimental part volatile aroma active substances were identified in green colored jelly candy samples available in the common market. For this purpose, the HS-SPME-GC-MS method was used. The individual samples differed in type and number of volatile compounds, depending on the manufacturer. In total 72 different compounds, including 11 aldehydes, 14 alcohols, 27 esters, 1 heterocycle, 8 carboxylic acids, 6 ketones, 4 hydrocarbons and 1 sulfur compound were found.
Napjatostně deformační analýza železničního mostu v Brně Černovicích
Gago, Viliam ; Hrstka, Miroslav (referee) ; Fuis, Vladimír (advisor)
The main subject of this thesis is stress and strain analysis of railway bridge in Brno Černovice as a typical example of steel truss construction. First section represents a theoretical summary, which is necessary for the right solution of this task. Next part describes analytic model for finding attributes of static determinate and indeterminate type of two-dimensional truss structure and their comparison. Those results are verified by numerical solution based on finite element method. The last part describes a three-dimensional model and shows a comparison with planar solution.
Biological effects of substances isolated from Isoptera species
Dušková, Simona ; Hrstka, Miroslav (referee) ; Brázda, Václav (advisor)
This thesis was focused on monitoring the viability of eukaryotic and prokaryotic cells after exposure of termites-isolated chemicals. Recently, evidence of antibacterial and antifungal properties of these defense substances has grown, and they can find a wide range of uses not only in the pharmaceutical industry. In this work, three defensive substances from termites were studied: nerolidol, nitropentadecene and methylanthranilate. Their antibacterial effects, minimal inhibitory concentrations and minimal bactericidal concentrations against Escherichia coli STBL3 strain were monitored. Further, their cytotoxic effects on eukaryotic non-tumor (HEK293FT) and tumor cells (MCF7) as well as their effect on plasmid DNA were studied. Antibiotic ampicillin and cytostatic cisplatin were used as control substances for antibacterial and cytotoxic effects, respectively. In the case of the action of nerolidol, nitropentadecene and methylanthranilate on the STBL3 strain, antibacterial activity was not demonstrated. Cytotoxic effects were observed nerolidol and nitropentadecene. None of the examined substances modified the plasmid DNA.
Aroma active compounds of selected types of herbs
Škutová, Pavla ; Hrstka, Miroslav (referee) ; Vítová, Eva (advisor)
This diploma thesis deals with the identification of aroma active compounds in medicinal herbs. The group consists of 5 types of herbs: lemon balm (Melissa officinalis), pot marigold (Calendula officinalis), clary sage (Salvia sclarea), milk thistle (Silybum marianum), goat’s rue (Galega officinalis). These plants are known for their positive effects in folk medicine. The SPME-GC-MS method was chosen to characterize the fragrances. During the identification of volatile compounds, emphasis was put on suspected fragrance allergens listed in EC Regulation 1223/2009 in Annex III. Overall 106 compounds were identified together with 8 allergens in lemon balm, pot marigold contained 104 compounds with 7 allergens included, 82 compounds including 5 allergens in clary sage, 73 compounds were identified in milk thistle including 6 allergens and 110 compounds with 9 allergens included in goat’s rue.
Design of optimal parameters of multilayer ceramic protective coating for high temperature applications
Dohnalík, Petr ; Hrstka, Miroslav (referee) ; Ševeček, Oldřich (advisor)
The main objective of this work was to design a suitable composition of a protective coatings, made of several different layers of specific materials - with respect to residual stress, induced due to a mismatch in thermal expansion coefficients of each layer. Protective coating in this work means both the thermal and the environmental barrier. These coatings protect components against high temperatures and harsh environment. In this work, necessary theoretical background in the field of the thermal and environmental barrier coatings is introduced. There are mentioned some basic design approaches, commonly used materials and processing methods for the coating structure. The literature review gives an overview of modeling of such coated structures, in particular it is devoted to the thermal barrier coatings deposited by air plasma spray process. The next chapter closely describes classical laminate theory used for calculation of residual stresses in the coating. One of the assumptions of this theory is homogenous temperature field through the coating’s thickness. However, in this work was revealed a way to extend the classical lamination theory of such cases, in which the temperatures vary along the thickness of the coating. In the practical part, the analytical model was used for designing suitable properties of some coatings, which were consists of two, three and four layers. The calculations were performed both for constant temperature and for the temperature gradient. All results obtained from analytical approach were verified by numerical calculations.

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