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Water soluble foundry binders with heat dehydratation hardening
Šebesta, Pavel ; Rusín, Karel (referee) ; Cupák, Petr (advisor)
Environmental pressure on foundries has forced manufacturers to develop new organic and inorganic binders. One of the options is water soluble binders that can be hardened by dehydration. In addition to tenacity characteristics and regenerability of the forming mixtures another considered aspect is the amount of emissions generated by casting. Use of these new binders does not require expensive modifications of the machines for work with the forming mixtures.
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Possibilities of waste glycerol reprocessing
Hýža, Bohumil ; Friedl, Zdeněk (referee) ; Kizlink, Juraj (advisor)
The aim of my bachelor thesis is to describe the possibilities of waste glycerol reprocessing. The thesis is purely theoretical and the information were obtained from various literary sources. Introduction of the study deals with the technological aspects of production of biodiesel by esterification of vegetable oils with methanol. Futhermore, there is described the amount of biodiesel produced in various countries around the world. In the theoretical part of the study are mentioned physical and chemical properties of glycerol and its traditional uses include the manufacture of nitroglycerin, the pharmaceutical use, etc. There are presented different technological methods for processing large quantities of glycerol too, such as steam reforming, which generates syngas which can be used for production of liquid fuels via Fischer-Tropsch synthesis. There is also desribed reduction of glycerol to propylene glycol with hydrogen. Other methods are dehydroxylation of glycerol to 1,3 - propanediol, halogenation of glycerol to produce epichlorohydrin, the catalytic dehydration of glycerol to acrolein and 3-hydroxy-propionic aldehyde, oxydehydration to polyacrylic acid, glycerol butylation over the Amberlyst catalyst and the formation of glycerol-tert-butyl ethers used as additives for fuels , polymerization of glycerol to polyglycerols, glycerol hydrothermal conversion to lactic acid catalyzed by alkali, esterification of carboxylic acids and glycerol to form glycerol esters, selective oxidation of glycerol to glyceric acid, tartronic acid and dihydroxyacetone, and glycerol as an additive for cement.
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Water soluble foundry binder with heat hardening
Prokop, Tomáš ; Burianová, Klára (referee) ; Cupák, Petr (advisor)
Foundry production produces the biggest amount of dangerous waste, which has a negative impact on environment and working conditions in the foundry. The foundry engineers test new technologies of shaping mixtures with new binders to protect environment and working conditions. We can reduce the production of dangerous waste by using better technologies and less harmful materials, which are needed for modeling forms and cores. The large source of pollution are binders, hardeners and catalyzer needed for binding sand. This work is focused on new types of ecological binders, which are dissolvable in water and are formed by setting temperature. These binders are ecological variants of known inorganic and organic binders.
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Voltammetric detection of 7α-hydroxycholesterol on boron doped diamond electrode
Serbanová, Lucie ; Schwarzová, Karolina (advisor) ; Nesměrák, Karel (referee)
This bachelor's thesis is dedicated to the electrochemical determination of 7α-hydroxycholesterol (7α-OHC) using boron-doped diamond electrode (BDDE). The work includes the optimization of experimental conditions and the measurement of the concentration dependence of 7α-OHC. The influence of various factors, such as water content in the solution and scan rate, on the electrochemical response of 7α-OHC was investigated. Various electrochemical methods, including cyclic voltammetry and differential pulse voltammetry, were used in the experiments. The electrochemical behavior of 7α-OHC in a solution of chloric acid and acetonitrile were analyzed. Important factors such as electrode passivation and response stability were carefully evaluated. The measurement of concentration dependence of 7α-OHC exhibited a linear response within the concentration range from 2∙10−5 mol l−1 to 1∙10−4 mol l−1 . Limits of detection (LOD) and quantification (LOQ) of 1,33 µmol l−1 and 4,43 µmol l−1 were determined. Comparison with other methods revealed that the electrochemical determination of 7α-OHC on BDDE achieves comparable sensitivity. The results of this work provide crucial insights into the electrochemical behavior of 7α-OHC, highlighting the advantages of BDDE for sensitive and reliable determination of...
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A new approach to the electroanalysis of primary bile acids and related steroids
Klouda, Jan ; Schwarzová, Karolina (advisor) ; Skopalová, Jana (referee) ; Vyskočil, Vlastimil (referee)
In this doctoral thesis, a novel method for the determination of primary bile acids cholic acid and chenodeoxycholic acid is presented. Bile acids play various vital roles in the mammalian body. Moreover, their determination is extremely helpful in liver and biliary disease diagnosis and management. These saturated organic compounds lack strong chromophores and fluorophores in their structure, and thus are usually hard to detect in spectroscopy. For this reason, either instrumentally advanced but expensive methods, such as mass spectrometry, or less reliable enzymatic methods are commonly employed in bile acids quantitation. Hence, the demand for simple and reliable methods for their determination is strong. Bile acids are also known to be virtually inert for direct electrochemical oxidation. Herein, a simple method for their chemical activation for electrochemical oxidation on bare electrode materials was developed, optimized and applied to cholic acid and chenodeoxycholic acid determination. The activation is based on a dehydration reaction of a primary bile acid with 0.1 mol L-1 HClO4 in acetonitrile (water content 0.55%) that introduces double bond(s) into the originally fully saturated steroid core. This naturally increases the electron density in the structure, and thus allows electrochemical...
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Development of voltammetric methods for detection of phytosterols on carbon-based electrodes
Zelenský, Michal ; Schwarzová, Karolina (advisor) ; Fischer, Jan (referee)
The aim of this diploma thesis was to develop an electrochemical method for three phytosterols, namely stigmasterol β-sitosterol and ergosterol using voltammetry techniques on glassy carbon electrode and boron doped diamond electrode. The work builds on previous results, where it was shown that the electrochemical oxidation of phytosterols requires perchloric acid in acetonitrile. When this acid is used, a dehydration reaction occurs. Calibration dependences were measured here for all phytosterols in an environment with a water content of 0.43%. The stability of the signal with increasing distilled water content was further investigated. Then the calibration dependences in the increased water content were measured again. If we want to use HPLC-type separation techniques, we must first find out how the phytosterols will behave in this environment, and therefore the signal stability on the buffer content was investigated. The buffers used were phosphate and acetate buffer. Subsequently, the concentration dependence was measured in an environment with a higher content of phosphate buffer. Furthermore, the possibility of detecting two phytosterols at once was investigated. Key words: dehydration, glassy carbon electrode, boron doped diamond electrode, oxidation, phytosterols, voltammetry
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Development of electroanalytical methods for detection of bile acids possessing 7α hydroxyl group
Jelšíková, Kristýna ; Schwarzová, Karolina (advisor) ; Dejmková, Hana (referee)
This master's thesis contains a study of electrochemical processes of selected bile acids possessing 7 hydroxyl group (cholic, chenodeoxycholic and −muricholic). The measurements were performed on boron−doped diamond electrode in the non-aqueous medium of acetonitrile and perchloric acid (water content 0.55 %) by cyclic voltammetry. It is known that the electrochemical activity of 7 bile acids is increased by a dehydration reaction between perchloric acid and the 7 bile acid. The subject of the study was the stability of the voltammetric response of chemically activated bile acids in the region of negative potentials. It was found that the presence of oxygen in the measured solution is an important factor for obtaining the cathodic signal of 7 bile acids. It probably performs a regenerative function; the product of the electrochemical reduction is re-oxidized in its presence, which leads to an increase in the voltammetric response. At the same time, it is important that the direction of the scan in cyclic voltammetry first proceeds to positive values. A potential of +2.0 V (vs. Ag/AgNO3 in acetonitrile) must be reached for the HO● radicals to be formed. It is these radicals that presumably lead to the formation of the product(s) of bile acids electrochemical oxidation that can be subsequently...
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Development of voltammetric methods for detection of bile acids and their conjugates
Petráňová, Karolína ; Schwarzová, Karolina (advisor) ; Nesměrák, Karel (referee)
The aim of this thesis is to study the electrochemical properties of bile acids and their conjugates. Specifically, cholic acid, chenodeoxycholic acid, taurocholic acid, taurochenodeoxycholic acid, glycocholic acid, and glycochenodeoxycholic acid were studied. The measurements were carried out on a boron-doped diamond electrode in an environment of acetonitrile and perchloric acid, with a water content of 0.55% in the solution by method of cyclic voltammetry. In order for bile acids to be electrochemically active, they must first be dehydrated, which takes place in a reaction with perchloric acid. This reaction requires a relatively long time, so it was accelerated by heating the compounds. The goal of this work was to determine the conditions under which the dehydration products of bile acids can be detected. The water content that can be added to the solution after dehydration to keep the voltammetric signal stable was determined. Furthermore, it was found that the voltammetric determination can be carried out even at a pH that is not extremely acidic in which is the the dehydration carried out. Finally, calibration dependencies were compiled.
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The meaning of hydratation old people from the perspective of nurses
GRIMM, Viktor
The aim of the bachelor work is to fulfill the following: 1. to research the nurses´knowledge of seniors´ hydratation, 2. to research the nurses´procedure of monitoring the seniors´hydratation and 3. to research the nurses´role in seniors´care concerning hydratation. To achieve the aims mentioned there have been seven research questions to be answered: What is the nurses´ knowledge in the field of hydratation?, How do nurses keep their knowledge and how do they extend it? Are there any significant differences as for maintaining and upgrading knowledge regarding hydratation among nurses of individual units? What are the hydratation signs nurses monitor and evaluate? Are there any differences as for the seniors´hydration procedures among nurses of individual units? What interventions concerning seniors´ hydratation care do nurses carry out? And How do nurses perceive their part of care connected with seniors´liquid intake? To get valuable information for the empiric part of the work there has been carried out a qualitative research method for which a semi-structured dialogue has been used.This dialogue included 22 open questions which were completed by follow-up questions if necessary, see the attachment 1.The questions were aimed at the following: what do nurses monitor while taking care of seniors in danger of hydratation, what are the key interventions the nurses carry out but also if they are being educated in this field and how important do they consider their part. The respondents were 6 general nurses who provide care for geriatric patients endangered by dehydratation. To analyse the research results the method of open coding, pencil-paper, was used. For better orientation the research results have been put into four main categories and several sub-categories. These logically created categories were set to deal with individual hydratation issues from the nurses´point of view, complexly, taking wider circumstances into consideration including nurses´education and their personal opinions on this topic.Thank to opinions of the general nurses, the most competent ones, the work´s results provide us with a complex view on the matter and that is why it can be used as the source of information not only for students, hospital attendants and nurses but also for common people who look after a senior at home and that is why they are highly interested in this issue.
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Pre-competition reduction of body weight in MMA
Hrdlička, Jaroslav ; Coufalová, Klára (advisor) ; Pavelka, Radim (referee)
Title: Pre-competition reduction of body weight in MMA Objectives: The main aim of this work was to identify what weight reduction methods are used by professional MMA fighters and how many kilograms they reduce before fights. We also wanted to determine the time they start to work with their body weight and whether they feel any psychological changes or fatigue due to weight reduction. We were also interested in what supplements fighters use during weight cut. Methods: A survey method was used for data collection. The research sample consisted of 20 professional MMA fighters between the ages of 18 and 40. Results: We have found out that MMA fighters usually reduce their weight through reduced caloric intake and subsequent dehydration the most. The majority of respondents reported a reduction of 6 to 10 kilograms in the course of 2 to 4 weeks before the fight. Respondents feel weakened during weight loss and experience psychological impacts such as irritation, mood swings, aggression and sedation. Before the fight, 60% of fighters do not experience any signs of weakness, as the time period from weighting to the fight itself is sufficient to allow them to regenerate. The most commonly used supplements during weight loss are BCAAs, fat burners, proteins, multivitamins and multiminerals. Keywords:...
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