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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Vývoj elektrochemického detektoru pro monitorování těžkých kovů

Koudelková, Zuzana January 2018 (has links)
The aim of this dissertation thesis "Development of electrochemical detector for heavy metal monitoring" was to create sensible sensors for the determination of heavy metals in the aquatic ecosystem and which would be usable for real applications, determination of the content of various metals in waste industrial waters. For the simultaneous determination of Zn(II), Cd(II), Pb(II) and Cu(II), a carbon paste electrode modified with chromium oxide was developed, based on this modification were produced the screen printed electrodes for the simultaneous determination of said metals with good limit of detection. For the usability of printed sensors in situ, a new electrochemical cell design was designed. This proposed cell also facilitates dosing of samples and buffer necessary for electrochemical analysis. Further, for determination of the total chromium content in aqueous solutions, was introduced a new method using a silver film on a glassy carbon electrode. Finally, various methods for waste water treatment from heavy metals have been tested.
42

Vliv zavadání, kontaminace píce zeminou a použitých konzervantů na kvalitu a zdravotní bezpečnost siláží vojtěšky seté

Spáčilová, Kristýna January 2018 (has links)
The aim of this diploma thesis was to evaluate the effects of wilting, soil contamination and use of silage additive on selected characteristics of green fodder and lucerne (Medicago sativa) silage. The plan material was obtained from the Research institute for Fodder Crops in Vatín. Unwilted fodder consisted in 24 % of dry matter content; wilted fodder consisted in 33 % of dry matter content. Selected samples were contaminated with soil at 30 g/kg of mass. Silage was in untreated variant (control) and two treated variants (either with biological additive or with chemical additive). Unwilted fodder had significantly (p<0,05) higher content of histamine and spermidine. Wilted fodder had a significantly (p<0,01) higher content of putrescine. In lucerne silage, factor of contamination had more significant (p<0,01) effect on ash content, and used silage additive had a statistically significant effect (p<0,05) on NDF content in silage. Significantly higher (p<0,01) content of clostridia was observed in silage from wilted fodder. The wilting factor had significantly higher effect (p<0,01) on content of ammonia, organic acids (LA, AA, PA, BA) and significant effect (p<0,05) on pH. Silage from wilted fodder was characterized by a higher pH, higher content of LA and lower content ammonia, AA, PA, BA. Contamination had significant effect (p<0,05) on increasing pH, reduction of LA and significant effect (p<0,01) on increased content of ammonia, AA, PA, BA. The silage additives significantly (p<0,05) decreased pH and significantly (p<0,01) decreased ammonia, PA, BA levels and increased LA, AA levels. The most abundant biogenic amines in silage were histamine (969 mg / kg), tyramine (800 mg / kg), putrescin (1754 mg / kg) and cadaverine (501 mg / kg). The biological additive used in the sufficiently wilted fodder works better to prevent the formation of biogenic amines and result in a more suitable fermentation profile.
43

Optimalizace molekulárně-biologických metod pro detekci kontaminant v koření

Došková, Markéta January 2017 (has links)
Contaminants are described in food generally, with narrower aim to spices in literary part of thesis. Bigger attention is dedicated to mycotoxins: secundary products of molds, basic survey, ways of assessment and legislation connected with their monito-ring. The main part of literary searches is focused on methods for microbial quality as-sessment of foods, then on description of classic and modern methods. Whereas samples of dried capsicum and pepper powders served as a samples for practical part, the end of theoretical part is devoted to individual steps for optimalization of new moleculary-biological method. The outputs of each steps are then parts of results and discussion, as well as other prospects and possible ways to future.
44

Možné způsoby kontaminace vodovodní sítě a posouzení zabezpečení vodojemů v okresu Plzeň-sever / Possible ways of contamination of water supply and analysing the security of water tanks in the Pilsen-North district.

DEJMKOVÁ, Andrea January 2018 (has links)
This diploma thesis is divided into two parts, theoretical and a part where the results are revealed. In the theoretical part the thesis is mainly focused on the characteristics of the chosen field. It then goes into further detail on the separate themes of each of the problems it is concerned with which is used in its research section. These themes are infrastructure and critical infrastructure, the description of the function of water management while also explaining the terms drinking water and water tank. The thesis also discusses solutions for a possible contamination by chemical, biological and radioactive matter. Terrorism is also discussed in the theoretical part of the thesis. The chosen methods for the evaluation of the results are quantitative and qualitative analysis on the basis of the corresponding technical documentation and business databases. The review of the safety measures used on waterworks objects and of the protection of the sources of drinking water was done through field research, during which, photo documentation was obtained and which was further analysed with varied criterion. There were important findings obtained through this research and it also pointed out the different levels of protection on water tanks in water systems in the Plzeň-North area. Detailed results are at the end of this thesis. With this thesis the author wants to point out the importance of protection of waterworks, mainly the protection of drinking water when it is distributed to its users. The failure to protect this commodity in its full extent would then have far-reaching impact, different from each other only in their extent. The most feared types of said emergency situations would be contamination or the interruption of drinking water supply. The main fields affected by these situations would be the food industry, healthcare, different branches of the industry, agriculture and many other, which are the ones ensuring optimal living conditions and safety for citizens not only in the Czech republic.
45

Hodnocení efektivity ochranných opatření přijímaných po černobylské havárii / Effectiveness evaluation of countermeasures adopted after the Chernobyl accident

ROTREKLOVÁ, Tereza January 2007 (has links)
The utilisation of nuclear energy entails, like any other human activity, risk of occurrence of accidents and emergencies. On Saturday 26th April 1986 early morning in the fourth block of the Chernobyl nuclear power plant in Ukraine occurred the biggest industrial accident in the peace usage of nuclear energy. It led to a vast leakage of radioactive debris to the wide surrounding area. An accident of such extent has never been thought possible before and it has surprised national authorities responsible for emergency preparedness practically in all counties operating nuclear power plants. It was crucial to prepare and introduce many countermeasures to restrict exposure of persons and environment to radiation. The most affected countries have been today{\crq}s Byelorussia, Russia and Ukraine. Although international instructions and criteria for failure actions had existed even before the Chernobyl accident, the experience with their application was very limited. Needless to say, some short-term countermeasures had been neglected or insufficiently realised. Inhabitants were not informed about the accident in time and therefore they hid late. Also iodine prophylaxis did not start in time, which led to unnecessarily high irradiation of thyroid gland. The evacuation was, in view of decreasing external exposure, executed within possibilities efficiently. As for the long-term countermeasures related not only to the liquidation of the aftermath of the accident in the area of the nuclear power plant but especially the decontamination works in residential units and on contaminated soils, regulation of food chains and relocation of persons from the affected areas, preventive and health care of the inhabitants living in the contaminated territory - these measures were massive in scope and in principle mostly reasoned and effective. Unfortunately, the effectiveness of some of these measures was somewhat deteriorated by the fact they were introduced area-wide (only on the basis of the surface contamination and not on the estimation of exposure from whole-body measurements), were not fully substantiated and later had to by cancelled for economical reasons. Not only economical factors play an important role in the planning and application of the countermeasures (mainly long-term ones). Without question it is necessary to secure that the measures can be applied in the contaminated areas in view of their effectiveness in sufficient extent for time long enough and after a thorough evaluation of all pros and cons, expenses and gains. As well, it is needed to take into consideration the effect of social and psychological factors, where in practise a satisfactory progress has not been made yet. Many studies proved that the introduction of countermeasures affects the increase of psychosocial tension among the involved people. This negative attitude results from the public{\crq}s lack of information about radiation and about the possibilities of its reduction and consequent fear and anxiety due to the uncertainty regarding future. Because of the concealment of information about the Chernobyl accident, also distrust of citizens against authorities has remained to be a problem. However, the approach of public is very important in regard to the effectiveness of countermeasures. In order that the measures would be accepted as well as possible, it is needed to secure corresponding education programs and to engage public into discussions and decision-making within the introduced measures.
46

Vliv stárnutí plastického maziva na jeho chování v blízkém okolí elastohydrodynamického kontaktu / Influence of the grease aging to its behavior in the vicinity of the elastohydrodynamic contact

Navrátil, Marek January 2019 (has links)
This thesis aims to describe the differences in grease behaviour caused by degradation. Observation of EHL contact and its surroundings is done using optical fluorescence, which allows to measure lubricant thickness even if it is discontinuous and air is present. New grease is observed, along with samples aged in bearings. One sample was worked for 1000 hours, which was the planned duration of the experiment. Two other samples were stopped prematurely after approx. 900 hours. Several possible age-related factors were examined and strong link between contamination and grease behaviour was found. In observed cases, contamination was identified to be the leading cause of lubricant shortage near EHL contact, which is one of possible bearing failure causes. The results expand existing knowledge about grease lubrication topic, but much further research is needed.
47

Kinetika příjmu hydrofobních organických látek v žížale Eisenia andrei v půdách s rozdílným obsahem organického uhlíku / Kinetics of hydrophobic organic compounds uptake in the earthworm Eisenia andrei in soils with different content of organic carbon

Šmídová, Klára January 2016 (has links)
This thesis is concerned with the fate of hydrophobic organic pollutants (HOCs) in soil. The theoretical part summarizes the current knowledge about bioavailability, factors influencing the bioavailability and methods for its measurement. Attention is paid to the organic carbon content, which is considered to be one of the key factors and to the influence of microorganisms that can degrade or interact with the substances, thus changing their bioavailable ratio. The practical part of the thesis uses bioaccumulation test with earthworm Eisenia andrei for evaluating the uptake kinetics HOCs in three soils with different organic carbon content. Soils were laboratory contaminated with mixtures of selected HOCs (phenanthrene, pyrene, lindane, p,p'-DDT and PCB 153) and the concentrations of substances in these soils were followed for 217 days. Subsequently, bioaccumulation test was conducted; earthworms were exposed from one to twenty-one days. The collected data were used to model uptake kinetics curves for individual substances. Peak-shaped bioaccumulation were found for pyrene, for lindane a steady-state concentration during exposure was observed, whereas for p,p'-DDT and PCB 153 growing concentrations after twenty days of exposure were detected. The reason for the different behavior of the substances was probably their diverse sorption on the organic material, which together with the different speed of elimination influenced final concentration in earthworms. Phenanthrene was not detected in some samples and therefore the modeling of uptake kinetics was not possible.
48

Posouzení vhodnosti PET drtě firmy PETKA CZ, a.s. pro výrobu granulátu k potravinářským účelům / Assessment of the suitability of PET flakes produced by PETKA CZ, Inc. company for the manufacture of granulates for food purposes

Šudomová, Lucie January 2017 (has links)
This thesis deals with the recycling of polyethylene terephthalate and its subsequent processing into the form of a regranulate meeting the parameters required for food use. A brief description of recycling technology, PET flake quality rating and input material contamination is provided. Additionally, legislation regarding recycling for food purposes is discussed and regranulation technologies are described. The suitability of these technologies for processing specific flake samples has been confirmed. In the experimental part, differences in the regranulate samples are compared using DSC and FT-IR. It has been found that there are no major differences between food quality samples. Tests were carried out on 200 PET bottles (bottle, label), on which the input material was divided into 16 groups. Groups that are unsuitable for recycling with this technology was defined. In addition, contaminants of the final product were examined. Their approximate composition was determined and the relationship between the labels of the bottles at the inlet and the impurities at the outlet was found. Appropriate solutions have been proposed to reduce this contamination
49

Proudění vody a vysoce propustné zóny v kolektorech východočeských křídových synklinál na příkladu jímacího území Litá a okolí / Groundwater flow and highly permeable zones in aquifers of eastern part of Bohemian Cretaceous Basin based on Litá area and surroundings

Lachman, Vladimír January 2010 (has links)
7 Abstract Groundwater flow and highly permeable zones in aquifers of eastern part of Bohemian Cretaceous Basin based on Litá area and surroundings In my thesis I deal with the character of highy permeable zones in marlstones and calcitic sandstones in east-bohemian synclines of the Czech Cretaceous Basin. My chosen area lies southwest of Nové M�sto nad Metují and within it lies Litá area, an important source of groundwater for Hradec Králové region. Groundwater in the area was contaminated in the 80's by chlorinated hydrocarbons. Based on a detailed field sampling of 23 boreholes and 4 sites of surface water performed in 2008 and on archival data on contaminant concentrations, I evaluate the character and relationships of groundwater from the boreholes. I grouped boreholes according to their chemical properties. In the second part of my thesis, I perform the analysis of the influence of faults on groundwater flow in a larger area of east-bohemian synclines. Results show that most yielding boreholes lie between fractures, not near them, which suggests the impermeable role of fractures. From available information I then try to answer the question of highly permeable zones of preferential groundwater flow. Based on the observed flow velocity,...
50

Monitoring kontaminace vod a sedimentů po těžbě uranové rudy / Monitoring of water and sediments contamination after uranium ore mining

Kurfürst, Vlastimil January 2011 (has links)
This paper deals with the monitoring of water contamination and sediments in the area of Olší - Drahonín. Firstly, the water contamination released into the river Hadůvka is evaluated. Secondly, the sediments in the river are monitored and the surface water flow is evaluated. Finally, the water treatment technology and sampling is described. A description of the separation methods and choice of standard methods is outlined.

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