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Study of sterilization effect of dielectric barrier discharge on eucaryotic microorganisms
Vojkovská, Hana ; Ing.Hana Grossmannová, Ph.D. (referee) ; Kozáková, Zdenka (advisor)
Nowadays the wide spectrum of decontamination methods are used for the inactivation of microorganism on various materials and subjects. The serious disadvantage of the conventional decontaminations methods is stressing of the exposed material by heat or chemicals. The presented bachelor thesis discusses plasma sterilization, which is more friendly and more effective on the wide spectrum of procaryotic and eucaryotic microorganisms. Basically, the main inactivation factors for cells exposed to plasma are heat, UV radiation and various reactive species The work was focused on studying of the effect of the dielectric barrier discharge (DBD) operating at atmospheric pressure on bioindicator Aspergillus niger. Plasma was generated in nitrogen and argon. Paper and PET-foil wer used as the carrying medium. The influence of various working conditions on the efficiency of plasma sterilization was studied. Namely it was the influence of plasma exposition time, plasma power density, the type of operating gas and type of the medium supporting the microorganism. According to our results the efficiency of the plasma sterilization increases with increasing plasma power density, resp. the plasma exposition time. When comparing the results observed for the same conditions in argon and nitrogen the higher sterilization effect was reached in argon. The sterilization time was 40 – 120 second in dependence to plasma power density, gas and carrying medium. Furthermore the influence of the carrying medium on the sterilization efficiency was prooved. It was shown, that porous materials have a ”shadowing effect” for microorganisms. The microorganism may penetrate into the paper material and embed in pits and cavities. Such penetration could preclude the interaction of plasma with the microorganism, thereby decreasing the efficiency of spore inactivation. Additionaly paper porosity complicates the detachment of spores into solution, so it is reached less microorganisms as from the PET-foil. The discharge parameters were studied by means of the optical emission spectroscopy.
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Study of sterilization effect of dielectric barrier discharge on procaryotic microorganisms
Bittnerová, Zuzana ; Ing.Hana Grossmannová, Ph.D. (referee) ; Kozáková, Zdenka (advisor)
Presented bachelor thesis is focused on sterilization effect of dielectric barrier discharge on procaryotic microorganisms. Sterilization is important biomedical and food-industry application and plasma sterilization is one of the method, which are suitable for sterilization of heat and chemical sensitive materials. Biologicaly contaminated samples were treated in dielectric barrier discharge operated at atmospheric pressure. The discharge was generated in argon and in nitrogen. Gram positive bacteria Bacillus subtilis was used as a bioindicator. Bacteria was spread onto the surface of paper and PET material. Efficiency of sterilization was evaluated according to exposure time, plasma power density and process gas. The positive effect of DBD on inactivation of microorganism was observed. The efficiency of the plasma sterilization increases with increasing treatment time. As regards plasma power density, the higher density was used the more effective the sterilization was and time necessary for inactivation of all microorganisms was shorter. Sterility was observed within 60 s while using plasma power density 2,37 W/cm, when using plasma power density of 1,78 W/cm longer treatment time is neccesary. The sterilization was more effective if argon was used as a process gas. Time necessary for the most reduction of microorganisms in argon was 10 s, while using nitrogen the reduction was only 50 %.
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Comparison of localization limiters for strain-softening
Květoň, Josef ; Vořechovský, Miroslav (referee) ; Eliáš, Jan (advisor)
It is well known, that simulation of crack propagation using the finite element method is dependent on mesh discretization. The thesis compares two approaches, that are designed to reduce the mesh influence: (I) the crack band model and (II) the nonlocal model. These localization limiters are applied to simulate three-point-bent beam with and without notch. The model of the beam is made with several variants of mesh discretization differing in finite element size and inclination. Performance of both localization limiters is discussed.
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Vliv povrchového materiálu na ohybové vlastnosti dřevotřískových desek s redukovanou hustotou
Havelková, Hana
The research was partially inspired by sandwich constructions, where the core delivering lightweight attribute and covering material the strength. In the research particleboards covered by different overlays were produced. The bending strength, modulus of elasticity, tensile strength and swelling properties were determined. Properties were compared with particleboard without overlay as well as between each tested group using Analysis of variance (ANOVA) and descriptive statistics. The HPL shown the most promising results while veneered surface delivered further questions considering swelling.
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Analýza sušení dřeva - ověření numerického modelu
Fousek, Jan
This thesis slew experimental determination and numerical simulation of the wood drying process with variable conditions, of the drying environment. For the calculation is used a mathematical model, describing the spread of bound moisture and temperature field in the wood on the basis of transport model using the gradient of temperature and humidity as driving forces. Wood Properties are considered as variable, depending on the density, humidity and temperature. Then is the simulation practically verified on a real measurement in laboratory conditions, which are corresponding with the simulation. Measured and calculated data are evaluated and compared to each other graphically and statistically.
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Influence of supplementary feeding on productive indicators of fishes
ZEMAN, Ondřej
This paper evaluates the influence of supplementary feeding of multi-species stocks with various densities on productive indicators of the common carp (Cyprinus carpio L.) and conversion of feeding. The chosen issue has been researched as a feeding experiment for 145 days at the joint-stock company Rybářství Třeboň, in four ponds of the Naděje fish pond system (Nadějská rybniční soustava) and two control fish ponds situated in the near of the village Ponědrážka. In the ponds, there were two different stocking densities. Fished were supplementary fed by heat treated wheat. The achieved results compare fishes' growth depending on the feeding conversion in various breeding condition.
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Vliv rozdílné techniky aplikace krmiva na produkci kapra obecného (Cyprinus carpio L.) v rybničních podmínkách
Weiser, Tibor
The aim of this work was to evaluate and compare the effect of the Carp - Feed feeding system with the feeding by standard way "by hand" at different densities of fish stock (2000 - 6000 pcs per ha) of common carp (Cyprinus carpio L). In the period of 24.4. -- 27.9. 2012 feeding tests in rearing of carp fry (mirror carp) in the ponds system in Milevsko were conducted. The feed mixture with the increased content of nitrogenous compounds at the level of more than 18% was used in the test. According to results, increasing of individual growth was found at 197 g (45%), resp. 52 g (25%) in the higher stocking density when using the Carp - Feed, which is caused by increased growth intensity by 6.1, resp. 2.2% in the relative daily growth and by 0.22%, resp. 0.044% per day in SGR. The production efficiency of food fluctuated in the range of 0.95 - 1.86 in FCR, 0.54 - 1.05 in FCE, 0.45 - 0.92 in FCR / SGR and 1.774 - 2.311% per day in specific growth rate SGR. The influence of feeding method and stock density on length and weight parameters, exterior and on chemical composition of muscle was statistically significant (P - 0.05). There was not proved any significant influence on fitness indicators. According to the observed results, it is suitable to use the Carp-Feed feeding system, but higher food consumption and lower individual weights at higher densities of fish stock have to be considered. That is why the aim of rearing should be set in advance. According to experiment, it is better to choose higher stock density (6000 pcs per ha) when using the Carp -- Feed for reaching the higher production in acceptable individual weight and for maximum yield. The literary review on feeding problems and possible modification of feed is also part of this thesis.
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Road and railway transport infrastructure in the Czech Republic
PAUR, Lukáš
The thesis focuses on transport infrastructure in the Czech republic. Its aiming at road, railway and combined infrastucture.It analyzes its current situation and short historical development. There is analysis focused on the density of infrastructure in european conditions and national regions in Czech Rep. Further, it analyzes the transport overload on chosen roads. Sugested solution is to move the road freigth to railway through combined transportation. Cost savings coming from lower reconstruction costs are calculated as well. In the end, there is proposal about implementation of combined transport in the region as a regional logistic center.
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The stability of biologically active compounds in elderberry (Sambucus nigra L.) inflorescence during processing
SUCHÁ, Renata
This thesis examines the stability of rutin in the inflorescences of the elder during processing. Elder (Sambucus nigra L.) is a medicinal plant that was used for medical purposes as early as in the Middle Ages. Both flowers (Flos Sambuci) and fruit (Fructus Sambuci) of the elder are on the list of official medicinal products of the State Institute for Drug Control. The main active phenolic substance is flavonoid rutin. Flavonoids are phenolic substances of plant origin. Among the best known properties of these substances is their antioxidant activity. They protect the low density blood lipoproteins from the oxidation modifications that cause the development of arteriosclerosis and hypertension. As a medical plant, the elder is used especially for the preparation of a medicinal drink. It is also commonly used as a material for the preparation of syrup. This product serves as a basis for a refreshing and tasty drink and lately is has also started to be sold in shops. For comparison, five single-flower syrups from the elderflower by different producers were bought. A method of preparation of the elderflower syrup was devised, based in one case on frozen elder inflorescences and in the other on dried inflorescences. The plant material came from wildly growing shrubs and it was collected in June 2013. Altogether, 8 syrups were prepared in the laboratory, 4 of them from fresh material and 4 from dried material. Two different methods were used. The first one was based on extraction using sugar solution, the second one on extraction using water solution where sugar was added afterwards. Another added substance was ethanol. The method for measuring the amount of rutin in the samples was a combination of two extraction steps. The first step was the usual exraction using aqueous methanol and the second step was extraction using a solid sorbent (SPE). The analysis of fresh and dried material concluded that dried elderflowers contain many times more rutin than fresh elder. Among the commercially produced syrups, the "Kitl Syrob Bezový" contained most rutin; a little less rutin was found in "Hamé Bylinný sirup Bezový květ". The concentration of rutin in the syrups prepared in the laboratory was much higher than in the commercial products. By using different methods of syrup preparation and their subsequent analysis, it was found that the syrups prepared from the dried inflorescences contained a higher amount of rutin than the syrups produced in the same way, but from frozen material. Addition of a small amount of ethanol had no effect on extraction of rutin from inflorescences. Free quercetin, which indicate a decomposition of rutin, wasn´t found in any of produced syrups. The produced syrups were used for the preparation of a drink and then underwent sensory analysis. The paired two-sided preference test included pairs of drinks consisting of a fresh elder drink and dried elder drink. The results showed that the evaluators preferred syrups from dried elderflowers in two of the cases, while in the other two evaluated pairs, the results were not statistically significant. In all cases, the evaluators most often found small and middle differences. The gained results show that the best method of syrup preparation uses dried plant material and sucrose solution as the extraction agent. The syrup prepared in this way contained most rutin and at the same time showed the smallest losses of this substance, which is beneficial to human health. Furthermore, it also tasted better in comparison with syrup prepared in the same way, but from fresh material.
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