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Water retention capacity of humic substances
Cihlář, Zdeněk ; Šmejkalová, Daniela (referee) ; Kučerík, Jiří (advisor)
Humic acids were extracted from South Moravian lignit. That humic sample was oxidized by either H2O2 or HNO3. In next step, oxidized humic acids were polymerized by formaldehyde in order to obtain cross-linked structures with improved water retention capacity. Affinity to water and water retention capacity of obtained products were studied by thermal analysis (DSC – differential scanning calorimetry and TGA – thermogravimetric analysis). In order to study above-mentioned parameters two different methods were used. First approach represented sorption of water to humic acids from three controlled humidities, for description of those processes TGA measurement was used. Second study was based on the DSC monitoring of water excess sorption. Results obtained from TGA measurements showed an increasing sorption ability with increasing relative humidity of the environment. DSC measurerents in hermetically sealed containers resulted in an increasing content of water bound by humic acids structures. All the modified samples of humic acids (oxidized as well as oxidized and modified by formaldehyde) gave higher retention capacity in comparion with the parental humic sample.
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Calcium aluminate hydrates - laboratory preparation and characterisation
Koplík, Jan ; Opravil, Tomáš (referee) ; Šoukal, František (advisor)
Calcium aluminate phases are important parts of Ordinary Portland cement and Alumina cement. Various calcium aluminate hydrates originate during the hydration of calcium alumina phases. Their origin depends on the conditions of hydration. In the diploma thesis was investigated hydration of four calcium aluminate phases – CA, CA2, C12A7, C3A under the conditions of four pH – 6, 9, 11, 12,65. Calcium aluminate phases were prepared from CaCO3 and Al2O3 by clinkering in solid phase in laboratory oven. The phases were hydrated for 48 hours. Kinetics of the hydration was investigated by calorimetry. Calcium aluminate hydrates were identified by XRD and DTA.
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Study of the influence of compositon on the mechanical properties of high performance concrete
Veleba, Ondřej ; Šoukal, František (referee) ; Krátký, Josef (advisor)
This work is devoted to study the influence of the composition on mechanical properties of high performance concret based on portland cement. 29 samples of high performance concrete (HPC) warying in composition were prepared. The constituents used for HPC preparation were: cement Aalborg White, silica fume, finelly ground blast furnace slag, finelly ground silica, calcinated bauxite and polycarboxylate based superplasticizer. The mechanical parameters (flexural and compressive strength) of the samples were observed after 7 and 28 days of moist curing. Compressive strength values after 28 days were in the range of 92 to 194 MPa and the flexural strength values were in the range of 7 to 23 MPa (without using of fiber reinforcement). The graphs showing mechanical parameters depending on the mixture composition were constructed and consequently evaluated.
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Calcium aluminates - hydration under various initial conditions
Tomala, Libor ; Másilko, Jiří (referee) ; Koplík, Jan (advisor)
This thesis deals with the preparation of calcium aluminate phases, namely monocalcium aluminate (CA), monocalcium dialuminate (CA2) and dodecalcium heptaaluminate (C12A7) and their hydration at temperatures of 20, 30 and 60 ° C. Preparation was carried out by sintering aluminium oxide and calcium carbonate in the correct molar ratio at a temperature typical for each of the phase preparation (1450, 1600 respectively 1360 ° C) in superkanthal furnace. Firings were conducted repeatedly until reaching the sufficient purity, which was determined by X-ray diffraction analysis on the diffractometer Empyrean from the PANalytical company. The pure calcium aluminate phases were subsequently hydrated in the already mentioned temperatures and progress was monitored on TAM Air isothermal calorimeter made by TA Instruments. The resulting hydrated products were identified again by using XRD.
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Effect of ground limestone addition on properties of cement-slag binder systems
Bílek, Vlastimil ; Másilko, Jiří (referee) ; Opravil, Tomáš (advisor)
This thesis deals with the effect of ground limestone addition on properties of cement-slag binder system. The evolution of compressive and flexural strength of binary and ternary systems (pastes), where 25 % of cement was substituted by one or two admixtures in different ratio, were determined and mutually compared. Granulated blast furnace slag and three different limestones were these admixtures. Two of that limestones were natural and one was prepared by a precipitation. For comparison, mixtures, where ash was added insted of slag, were prepared. The mechanism, by which finely ground limestone participates in hydration process, was studied by conduductometric measurements of systems simulating conditions in fresh pastes, and by TG-DTA method, which was used to determination of added limestone amount which remains in its original form and the amount which participates in the formation of hydration products.
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Hydration of biomolecules
Flimel, Karol ; Janeček, Jiří (referee) ; Kučerík, Jiří (advisor)
The aim of this thesis was to apply methods of thermal analysis (differential scanning calorimetry and termogravimetry) to study kinetics of water evaporation from hyaluronan. This approach allowed to determine the changes of desorption energies in the course of evaporation and consequently helped to improve the understanding of the hyaluronan hydration. Thermoanalytical methods in combination with model-free kinetics previously suggested by Ozawa were used to determine kinetic parameters of studied processes. Results confirmed previous knowledge about the content of water located in primary hydration shell of hyaluronan, i.e. concentration range from 0.4 – 0.8 g of water per 1 g of hyaluronan. Further, it was found out that during the evaporation in this concentration range, the hyaluronan gel, stabilized probably by hydrogen bonds, is formed.
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Effect of cosmetic massage on a selected group of women
DVOŘÁKOVÁ, Miroslava
This thesis examines the influence of cosmetic massage to a select group of women, the research relates to the impact of regular massage and treatment on hydration and overall skin condition and cosmetic massage influence on the psychological state of the respondents. The theoretical part defines the concept and importance of massage, composition and function of the skin, explains the process of skin aging. The task of the practical part was to confirm the assumptions that regular cosmetic massage has a positive effect on skin condition, increases the level of hydration of the skin and slows aging and delays the formation of wrinkles. Assumptions proved correct. Cosmetic massage acts on the skin's condition and mental well-being of women positively.
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Preparation of patient prior to application intravenous of contrast medium in relation to the prevention of renal failure
PUCHOLTOVÁ, Lenka
The topic of the bachelor thesis is the patient preparation prior to intravenous contrast in relation to the prevention of renal failure. The theoretical part deals with the anatomy and physiology of the kidney, provides information about the contrast media of their properties, uses and side effects. At the end of the theoretical part describes the contrast medium-induced nephropathy. In the practical part I focused on finding out what is the incidence of contrast nephropathy in individuals with normal creatinine levels depending on the amount of contrast agent and the preparation of the patient. I obtained the data from the hospital information system Masaryk Hospital Townsville. The database contained a set of hospitalized patients in the years 2009 - 2011, which were performed CT examinations associated with the administration of iodinated contrast media. Part of the personal data of patients, the tests used, the type and amount of contrast agent and creatinine values. Since creatinine values were available for all patients, the final database was created from 938 patients with baseline of normal creatinine levels before the examination for which they may be level <than 130 mmol/l. The final group of patients was analyzed according to the defined aims and statistically processed. Hypothesis of this study: the incidence of contrast nephropathy in individuals with normal creatinine levels depending on the amount of contrast agent as a suitable preparation of patients prior to administration of iodinated contrast material does not exceed 10% - was confirmed. In the investigated group of patients was proved preventive effect of patient preparation before the test - hydration. A higher incidence of CN was observed in the group of patients whose preparation has taken place.
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