|
| |
|
|
Application of Atomic Absorption Spectrometry for Determination of Selected Elements from Potential Ecological Burden Area
Juránková, Lada ; Hraníček, Jakub (advisor) ; Šíma, Jan (referee)
This work is focused on the determination of selected (chemical) elements (Fe, Mn, Zn, Cr, Na, K, Mg a Ca) in a potential ecological burden area using flame atomic absorption spectrometry as a detection technique. A potential ecological burden is represented by tires which are used as a construction material or as an environment surrounding for growing decorative and consumable plants. Analytes were determined in plant origin samples. Firstly, the samples were dried in a laboratory electric dryer. The weighted amount of a dried sample (approximately 0.2 g) was digested inside a microwave decomposition device with an addition of nitric acid and hydrogen peroxide. An optimization of experimental parameters was done for each of the elements before sample measuring. A burner height was optimized and 8 mm height was chosen as a optimum for most elements. Under the optimum condition basic characteristics were measured for each element separately. These characteristics included limits of detection that were: 0.05; 0.01; 0.08; 0.21; 0.02; 0.01; 0.01; 0.01 mg L-1 for the following elements: Fe, Mn, Zn, Cr, K, Ca, Mg and Na, respectively. The limits of quantification, sensitivity and repeatability were determined for each element as well. A significant attention was paid to the content of zinc in the studied...
|
|
|
Determination of selected elements in plant extracts by atomic absorption spectrometry
Rydlová, Lenka ; Hraníček, Jakub (advisor) ; Kratzer, Jan (referee)
The aim of this bachelor thesis was to determine selected elements (Na, Mg, K, Ca, Zn, Se) in plant extracts and juices by atomic absorption spectrometry using different types of atomization. Each method has been optimized for determination of the mentioned elements. For flame atomization it has been used optimization of height of the primary radiation from the hollow cathode lamp over the edge of the burner. The height was generally between 6.0 and 8.0 mm. Then there have been optimized flow of each component of the flame (acetylene, air, nitrous oxide) and it has been set location of the hollow cathode lamp and the flame. Under the optimized conditions basic characteristics describing the method of the determination of mentioned elements have been measured (LOD for sodium 2.13 µg L-1 , for magnesium 2.44 µg L-1 , for potassium 11.3 µg L-1 , for calcium 15.6 µg L-1 , for zinc 6.04 µg L-1 , for selenium 0.34 µg L-1 ). In the next part of the thesis the optimized methods have been used for measuring concentration of all elements in real samples. After the preparation of the samples including dilution, addition of various reagents etc., they have been atomized by flame in an atomic absorption spectrometer (Na, Mg, K, Ca, Zn) and determined, or converted to a volatile compound (Se) and determined by...
|
|
|
The content of selected metals in soil as an indicator of contamination due to the road traffic
VOLAVKA, Tomáš
The soil, as a part of ecosystem, is permanently endangered by pollution and exposed to degradation. A large share on this pollution has a human. This problem is caused mainly by industrial production, agriculture and transport. Intensive chemical maintenance is necessary during winter. It is because of better driving on the roads. Chemicals gradually soak into the soil and contaminate it. This master thesis deals with the analysis of soil samples from close proximity of road from Veseli nad Luznici to Trebon. There was analyzed the concentration of copper, sodium and zinc. Samples were collected in two depths: from 0 to 15 cm (surface sample) and 15 to 30 cm (subsurface sample). The mentioned metals were analyzed by atomic spectrometry. The measured value concentration of copper was between 2.24 mg-kg-1 and 84.35 mg-kg-1, the sodium concentration was from 11 mg-kg-1 to 1 697 mg-kg-1 and the zinc concentration was in the range of 9 mg-kg-1 526 mg-kg-1. The highest concentration of copper (84.35 mg-kg-1) was found in the subsurface sample taken from the immediate proximity of the railway in February 2017. The highest concentration of sodium (1 697 mg-kg-1) was measured near the road in February 2016. The highest concentration of zinc (526 mg-kg-1) was measured near railway in October 2015.
|
|
|
Expanded Grpahite as Negative Electrode Material for Aporotic Intercalation Systems
Kaňa, Michal ; Čech, Ondřej (referee) ; Libich, Jiří (advisor)
This thesis deals with lithium-ion batteries. It focuses primarily on the materials which are the basis of negative electrode materials, especially on natural expanded graphite. The aim of this thesis is delineate problems of lithium-ion batteries and the possibilities how to improve their basic parameters such a capacity and current carrying capacity. The first part focuses on the description of the functionality of a lithium-ion battery. The second part focuses on the production of negative electrodes, measuring their properties and characteristics. In the last part, there are evaluated and compared individual negative electrode in the role of host of lithium and sodium ions according to the obtained data and then there are the conclusions draw
|
|
|
The amount of salt in the diet received by selected adult individuals and the effect of this amount on blood pressure
DVOŘÁKOVÁ, Tereza
The work deals with the issue of high salt intake in the diet and with health complications that are related - especially high blood pressure, hypertension. The aim of bachelor thesis was to describe the amount of salt in the the diet received by selected adult individuals and the effect of this amount on blood pressure. The work is divided into two parts - theoretical and practical. In the theoretical part the problem is defined. The practical part is focused on a qualitative research, which was conducted through monitoring and recording the collected data into created forms. The data collection technique was weighing of all ingredients in food preparation, measurement of the blood pressure of the respondents and laboratory analysis of urine per 24 hours. Evaluation of the data was performed using a program Nutriservis Profesional together with use of nutrition information pictured on the packaging of the food. The research group consists of five respondents, two men and three women. The results are presented in text form, summary tables and results from the laboratory. They indicate, that after averaging the resulting figures of salt intake for each day, no respondent complies with the recommended amount and with this fact corresponds even the BP. Three respondents have normal blood pressure (prehypertension), and two have optimal BP. As the most significant sources of salt were confirmed smoke meat products, bakery products and cheese.
|
|
|
Content of NaCl in hypertonics at the ordination of the practical doctor
JANOUŠEK, Matěj
The main aim of this bachelor thesis called "Content of NaCl in hypertonics at the ordination of the practical doctor" is to determine the diet quality of people suffering from high blood pressure. The emphasis is put on sodium intake and the overall energy from protein, fats and carbohydrates. The theoretical part deals with salt both from historical and contemporary point of view. In the centre of my attention is the overuse of salt, salt occurrence in food and the need to reduce the amount of salt in our overall diet, for it has negative health effects. This work also deals with the hypertension itself. I explain its definition, division, pathogenesis and the individual factors. I also mention the increased probability of illness which may occur due to hypertension. Another important part of my work is the recommended lifestyle and precautions both for prevention and cure of hypertension. The practical part deals with the conducted research. I assess the forms from my respondents. These week forms enabled the respondents to keep track of their diet. The forms were given to people suffering from hypertension by their practical doctor, who gave me back those filled-in forms later. Respondents also filled-in their weight, height, age and sex. The collected data were processed via a programme called "Nutriservis professional". I calculated the recommended energy intake from protein, fats, carbohydrates and sodium based on the collected data, which I compared with the findings of Nutriservis. These findings show us, if the energy intake from protein, fats, carbohydrates and sodium is according to the recommended values. The final discussion generalises my findings.
|
|
|
Influence of calculation accuracy on final parameters of heat exchanger
Matyska, Stanislav ; Radil, Lukáš (referee) ; Foral, Štěpán (advisor)
The aim of this thesis is to make the design of the heat exchanger more accurate. It is assumed that the division of the tube bundle of the heat exchanger to a plurality of parts by the transferred thermal output can achieve more accurate values. The first part of this thesis is dedicated to the sorting of the heat exchangers according to different criteria, and a brief description of most of them. It describes what are their functions and what are the demands placed on them. Next, there is given a detailed description of the tubular heat exchanger, specifically the mantle one because it is fundamental for this thesis. To investigate the influence of calculation accuracy, there is selected a reference heat exchanger, which processes the study. There are described the main characteristics for the reference heat exchanger (transferred thermal output, heat transfer fluids, their temperature on inputs and outputs) and its construction (geometry of the heat exchanger, number of tubes, tube geometry). The thesis also discusses the influence of calculation accuracy of the heat exchanger at its parameters. In the next part, there is made a basic calculation of the tube bundle length and the pressure losses of the proposed heat exchanger. Here are assembled the theoretical basis for the calculation by dividing the tube bundle. Specific calculations are performed so that the tube bundle of the heat exchanger is divided into a selectable number of parts by the transferred thermal output. In each section, there is performed a calculation of the length of the specific tube bundle part. Individual lengths are added up and finally put together the entire tube bundle length. At the end of this section, there are calculated the pressure losses in the heat exchanger in a similar manner as for the calculating the total length of the tube bundle. In conclusion of this thesis there are described and clarified the results of the calculations. It examines the difference between the results of the reference and the proposed heat exchanger.
|
|
|
Sodium cooled fast reactors
Daňhel, Aleš ; Katovský, Karel (referee) ; Foral, Štěpán (advisor)
This bachelor’s thesis deals with the sodium-cooled fast reactors. It comprehensively describes the problem of sodium-cooled fast reactors. Attention was paid to the basic specifications and parameters of these reactors. There was briefly described nuclear reactions which are under way in core of sodium-cooled fast reactors but also chemical reactions which are linked to function of liquid sodium as a coolant and heat transfer substance. Attention was also paid to the differences in the reactor core configuration and to the machine device specific for sodium-cooled fast reactors. Further on this bachelor’s thesis puts on the overview of sodium-cooled fast reactors that have worked, are still working or are under construction in each country all over the world. There was briefly described generation IV nuclear reactors, particularly its history and reasons that originate generation IV. Under generation IV was also described nuclear reactor SFR and highlighted differences compared to existing sodium-cooled fast reactors. In the practical part of this bachelor’s thesis is easily made a calculation of the heat transfer from the fuel rod to the cooling sodium and there is also mentioned course of the heat transfer coefficient along the fuel rod. This calculation was made by computing program MATLAB.
|
|
|
Preparation and characterisation of ceramic electroactive materials for Na-ion batteries
Vaněk, Martin ; Libich, Jiří (referee) ; Čech, Ondřej (advisor)
Hlavním cílem této práce je charakterizace vzorků titanátů, jako materiálů pro sodíko-iontové (Na-ion) akumulátory. Syntéza některých vzorků je součástí této práce. Charakterizace je zaměřena na elektrochemické vlastnosti, složení a morfologii použitých materiálů. První část se zabývá lithium-iontovými (Li-ion) akumulátory. Byly vybrány, protože jsou ve vědeckých článcích dobře popsány a základní funkční princip je aplikovatelný také na Na-ion akumulátory. Materiály používáné pro katody, anody a elektrolyty následují po krátké části shrnující parametry a konstrukci Li-ion akumulátorů. Následující kapitola je zaměřena na sodíko-iontové akumulátory. Srovnání sodíku a lithia je následováno materiály používanými pro elektrody a elektrolyty (s důrazem na anodové materiály). Třetí část popisuje analytické metody použité pro charakterizaci elektrod a materiálů. Jedná se o elektrochemickou charakterizaci (cyklická voltametrie a galvanostatické cyklování s potenciálovým omezením), morfologii (rastrovací elektronová mikroskopie) a složení (X-ray difrakční spektroskopie). Poslední dvě kapitoly obsahují syntézu a charakterizaci sodného titanátu a charakterizaci dvou vzorků TiO2. Výsledky této práce jsou shrnuty v závěru.
|
guest ::
