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The influence of hydration accelerators on cement doped with zinc
Beneš, Pavel ; Šilerová,, Iva (referee) ; Šiler, Pavel (advisor)
Zinc in cement has negative properties mainly due to a significant delay in hydration. This bachelor thesis deals with the study of hydration of cements containing zinc. The course of cement hydration was monitored by isoperibolic calorimetry. Zinc was doped to CEM I 42.5 R in the form of 1 weight percent zinc oxide. Calcium oxide, formic acid and calcium formate were used in various proportions as accelerators. The obtained results were compared with the measured strengths and finally the suitability of the given accelerators was discussed for use in construction application.
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Influence of zinc on mechanical properties of cement composites
Štarha, Tomáš ; Šilerová,, Iva (referee) ; Šiler, Pavel (advisor)
The theme of this bachelor thesis is to monitor the effect of zinc on mechanical properties of portland cement. Zinc was tested in the form of zinc oxide. Three acceleration additives were added, calcium oxide, formic acid and calcium formate in various proportions. Furthermore, the mechanical properties of all these mixtures were monitored by measuring flexural strength and compressive strength at 7 and 28 days after mixing and mixtures were analyzed by XRD and DTA. Also using isoperibolic calorimetry, the hydration of CEM 42.5 R cement zinc oxide was monitored.
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Influence of hydration accelerators on zinc - doped cement mortars
Beneš, Pavel ; Šilerová, Iva (referee) ; Šiler, Pavel (advisor)
This work deals with monitoring the hydration of cement mortars and cement pastes made from CEM I 42.5 R cement doped with zinc oxide in an amount of 1 % wt. To eliminate the delay in the onset of hydration due to the presence of zinc oxide, the following accelerators were added to the cement mixtures in different proportions: calcium oxide, formic acids and calcium formate. Hydration was monitored using isoperibolic calorimetry. Furthermore, the mechanical properties of mixtures were investigated, namely the tensile strength after bending and the compressive strength after 7 days and after 28 days. The cement mortars were further subjected to additional analyses, such as porosimetry, DTA/TG and SEM.
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HIGHT-RATE SUPERCAPACITORS BASED ON CONDUCTING POLY(3,4 ETHYLENEDIOXYTHIOPHENE)
Ivanko, Iryna ; Tomšík, Elena (advisor) ; Uchman, Mariusz Marcin (referee) ; Perrin, François-Xavier (referee)
An understanding of the effect of molecular structure on physicochemical properties of organic semiconducting polymers requires a proper method of preparation during which it is possible to obtain a polymer with a well-defined chemical structure. Therefore, in this work three methods of preparation of poly(3,4-ethylenedioxythiophene) (PEDOT), such as chemical oxidation, electrochemical polymerization, and a new method, namely acid-assisted polymerization, were utilized. Using chemical oxidation polymerization, it was investigated the effect of ions from Hofmeister series, specifically formate ion, on PEDOT physicochemical properties. In particular, it was shown the formation of hydrated oligomer chains which assemble into semicrystaline structure. Moreover, it was demonstrated that hydrated oligomers undergo rearrangement of its chains during the electrochemical treatment with the formation of anisotropic structure, and unique photoluminescence properties. Next method for PEDOT preparation, which was for the first time introduced by us, is acid-assisted polymerization. It was shown that it is possible to prepare, by using polar Brønsted acid, the PEDOT solution without applying oxidant at room temperature. Moreover, we have shown a way to control the optical properties of PEDOT, by the mean of a...
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Influence of zinc on mechanical properties of cement composites
Štarha, Tomáš ; Šilerová,, Iva (referee) ; Šiler, Pavel (advisor)
The theme of this bachelor thesis is to monitor the effect of zinc on mechanical properties of portland cement. Zinc was tested in the form of zinc oxide. Three acceleration additives were added, calcium oxide, formic acid and calcium formate in various proportions. Furthermore, the mechanical properties of all these mixtures were monitored by measuring flexural strength and compressive strength at 7 and 28 days after mixing and mixtures were analyzed by XRD and DTA. Also using isoperibolic calorimetry, the hydration of CEM 42.5 R cement zinc oxide was monitored.
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The influence of hydration accelerators on cement doped with zinc
Beneš, Pavel ; Šilerová,, Iva (referee) ; Šiler, Pavel (advisor)
Zinc in cement has negative properties mainly due to a significant delay in hydration. This bachelor thesis deals with the study of hydration of cements containing zinc. The course of cement hydration was monitored by isoperibolic calorimetry. Zinc was doped to CEM I 42.5 R in the form of 1 weight percent zinc oxide. Calcium oxide, formic acid and calcium formate were used in various proportions as accelerators. The obtained results were compared with the measured strengths and finally the suitability of the given accelerators was discussed for use in construction application.
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Determination of Arsenic Using UV-photochemical Generation of the Volatile Species in Formic Acid Medium with AAS Detection
Vlčková, Anna ; Červený, Václav (advisor) ; Hraníček, Jakub (referee)
V této bakalářské práci byla nejprve sestavena aparatura pro stanovení arsenu pomocí UV-fotochemického generování jeho těkavé sloučeniny s AAS detekcí a byly optimalizovány experimentální podmínky navrhované metody. Klíčovými parametry byly: délka reakční cívky ozařované UV světlem; místo zavádění reakčního plynu (vodíku) před UV-fotoreaktor a nosného plynu (argonu) před UV-fotoreaktor a do separátoru fází a jejich průtoky; koncentrace kyseliny mravenčí v nosném roztoku a jeho průtoková rychlost a velikost dávkovaného objemu vzorku. Za optimálních podmínek navrhované metody byla naměřena kalibrační závislost. Pro porovnání výsledků bylo použito stanovení arsenu pomocí chemického generování jeho hydridu. Z porovnání těchto metod vychází chemické generování jednoznačně jako metoda citlivější, protože lze stanovovat koncentrace již od 5,7 ppb As, zatímco metodou UV-fotochemického generování lze stanovovat koncentrace až od 150 ppb As. Za stávajících podmínek je UV-fotochemické generování těkavých sloučenin z důvodu velmi nízké citlivosti (přibližně 16,5 % oproti chemickému generování) pro stanovení arsenu nevhodné.
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Interference study by selenium determination using UV-photochemical generation of its volatile species in formic acid media with AAS detection
Duben, Ondřej ; Červený, Václav (advisor) ; Kratzer, Jan (referee)
The aim of this work was to experimentally observe the impact of various potential interferents on the determination of selenium using UV-photochemical generation of its volatile species in formic acid media with AAS detection. HNO3, As3+ , Co2+ , Cu2+ and Ni2+ were chosen as model substances affecting the analyte response. All these substances were found significant interferents. Some of these substances (HNO3, As3+ , Cu2+ , Ni2+ ) increased the signal at low concentration, but the signal of selenium decreased significantly at their higher concetration in a sample. Inverse shape of the dependence of the analyte response on the interferent concentration was observed for Co2+ ions. It was found that the reagent Chelaton II, often used in analytical chemistry to mask interferents, also caused a suppression of selenium signal. On the contrary, other maskig agents tested (triethanolamine, amonnium formate) did not lead to any interference. Key words: selenium, UV- photochemical generation of volatile compounds, formic acid, AAS, interference, masking
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Premedical care for patients with methanol intoxication
KŘENEK, Jan
Intoxication through methanol is a relatively less frequent type of poisoning, which can lead even to a serious damage to the human body; can cause loss of vision as well as permanent infliction of the central nervous system. And also the death of the afflicted person is possible with late treated conditions. The methanol metabolites are quilted for the damage of the human body - mainly formic acid that is why the therapy of this health and life-threatening condition is mostly focused on the metabolism of methanol. The theoretical part deals with pre-medical that is pre-hospital emergency care of patients with a methanol intoxication. The first chapter deals with the pre-hospital emergency care, a medical rescuer and his competencies, and the ambulance crew is listed here as well. Furthermore, the theoretical part of the thesis deals with the acid-base balance, metabolic acidosis, but also involves the Toxicological Information Centre. The next chapter explore methanol and its characteristics and the history of methanol in the course of the human civilisation. It explains the metabolism of methanol and highlights the symptoms of acute and chronic methanol intoxications. The last chapter is directly focused on first aid in this state provided by a layman; and on the treat methanol intoxication in terms of pre-hospital emergency. Last but not least, it is also concerned with the effects of the methanol intoxication. The practical part of the thesis is focused on mapping the activities of a paramedic in a pre-medical care of a patient with a methanol intoxication and on determination the level of awareness of laity as well as the clients of the sobering-up station for this type of poisoning. As well as a laity with help of anonymous questionnaires. The research survey was conducted through the quantitative method among the paramedics. The amount of the data was collected during the March 2015. The research group were the randomly choired laymen and clients of the sobering-up station and the paramedics working in the Emergency Medical Services of South Bohemia Region at the regional centres of Strakonice, Písek, Prachatice, Český Krumlov and Jindřichův Hradec. The anonymous questionnaire was distributed to the above stated regional centres in the number of 100 pieces, for the laity in the same number and 10 pieces for the sobering-up station in České Budějovice. The questionnaire for the paramedics contained a total of 18 questions. The first four questions were the ones of stratification, the questions no 5 to 18 were closed and directly addressed the issues concerning the provision of pre-hospital emergency care in methanol intoxication, whereas the hypothesis no. 1 was confirmed. The questionnaire for the laity in itself contained a total of 14 questions. The first three questions were of socio demographic character. The fourth question was closed and crucial to the continued questionnaire. The question no. 5 was semi-open and remaining questions no. 6 to 14 related to determine the level of awareness among the laity methanol intoxication. The results are processed into clear graphs and the related hypothesis no. 2 was also confirmed. The first goal was to map the activity of a paramedic in a pre-medical care of a patient with a methanol intoxication. The second objective was to determine the level of awareness of the laity of this intoxication. Both the objectives have been met. The statistical method of processing a research survey showed that paramedics are knowledgeable in the procedures of pre-medical care for patients with a methanol intoxication and that lay people are informed of this intoxication, but would welcome more active involvement of experts in informing society about this issue. Based on the results of the work an information leaflet was produced for the lay and paramedics in the field of alcohol intoxication.
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