National Repository of Grey Literature 32 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Study and characterization of organic substances in a biochar sample
Vojáčková, Beáta ; Kalina, Michal (referee) ; Enev, Vojtěch (advisor)
This bachelor thesis characterizes biochar from a physico-chemical point of view. The theoretical part deals with biochar as a soil conditioner, its properties, use, production, and last but not least, effect of its sorroundings. For better characterization of organic and inorganic matter a phosphate buffer was used. This buffer ensures their specific extraction due to a neutral pH. The second path is to use rainwater, which simulates the condition of the soil environment. In the experimental part are discussed both; purified buffer-extracted samples and rainwater samples, which were studied by thermogravimetric analysis (TGA), elemental analysis (EA) and by infrared spectroscopy with Fouier transform (FTIR-ATR). Conductivity and pH were also measured. Moisture and ash content, which represent the inorganic non-combustible fraction, were determined using thermogravimetry. The extraction yields were converted to ashless wt. % based on these values. Results of EA provided us with information on the content of biogenic elements and basic physico-chemical characteristics of biochar. In contrast, the FTIR method defined the presence of individual functional groups and specific constitutive units, which are present in the extracts. This information allows us to better understand the environmental impact of biochar on the soil ecosystem.
Biosensors based on modified nanoparticles
Mihajlović, Ana ; Majzlíková, Petra (referee) ; Hubálek, Jaromír (advisor)
This thesis deals with biosensors based on modified semiconductor quantum dots(AIIBIII). This work is divided into three main parts. The first deals with the theory necessary for the use of QDs in bioapplications, there are described methods of synthesis, application and bioconjugation of QDs . In the practical part, GSH-CdTe, CdTe-MPA and TGA-CdTe quantum dots were prepared by direct colloidal synthesis. These quantum dots were then modified by EDC in order to increase affinity to BSA (bovine serumalbumin). For the analysis of samples were used Infinite M200,Tecan and HORIBA Jobin Yvon FluoroLog detector Quanta . The third part is the summary of results and work achievements.
Soil gel as a suitable matrix for the study of humic substances in the soil ecosystem
Černý, Pavol ; Pekař, Miloslav (referee) ; Enev, Vojtěch (advisor)
This master's thesis deals with a complex issue of soil gels. The main goal of this work is to optimize the process of isolation of soil gels out of the soil matrix. Isolation is carried out using only water and therefore represents a promising method for study of humic substances (HS) in natural form. Modal brown earth from the area of Veverské Kninice was used as a soil matrix for isolation. The isolated soil gel was phisicochemically characterized by thermal and spectroscopic methods. By using EA and TGA, the content of biogenic elements in the organic component of soil gel and the content of the inorganic component was determined. The inorganic component represents a majority share in structure of soil gel with values up to 90 % w/w. Mineralogical composition of the inorganic component was described using XRD, with quartz being the most represented. Chosen macro and microelements were determined by ICPOES and the results show a noticeable increase in the content of some elements, that form complexes with HS. Organic component was studied using spectroscopic methods FTIR and XPS, which clearly showed that the primary components of the organic matrix are HSs. For this reason, absorption coefficients EET/EBZ, E2/E3 a E2/E4 were determined using UV/Vis spectrometry. Morphology of isolated soil gels was studied by using SEM and the photographs show mineral particles covered with clusters of humic matrix.
Properties comparison of two products used for skating rink based on ehtylene-propylene-dien rubber
Kostková, Jana ; Kučera, František (referee) ; Bálková, Radka (advisor)
This master thesis deals with characterization of two black and white products based on ethylene-propylene-diene rubber (EPDM) used for skating rink. Products marked with A and are different in their diameter of circular tubes trough which cooling medium passes and also in the distance of these tubes. Both of materials were characterized in order to determine whether it is the EPDM and how are they different. The characterization methods were used: differential scanning calorimetry, thermogravimetric analysis, attenuated total reflectance Fourier transform infrared spectroscopy, tensile test, swelling test, thermooxidative test. The composition of both materials, including fillers and others additives is almost the same but difference is in structure of EPDM and probably also in interaction with fillers, what exhibits different mechanical properties, thermooxidative stability and thermal capacity. These differences which have been found are essential for long-term use properties of both materials.
Thermoplastic composites for automotive applications
Zbončák, Marek ; Pospíšil,, Ladislav (referee) ; Jančář, Josef (advisor)
Diplomová práca sa zaoberá prípravou teromplastických kompzoitov s PMMA a PC matricou s potenciálnym využitím v automobilovom priemysle. Ako výstuž boli použité krátke sklenené, uhlíkové a PBO (poly(p-fenylén benzobisoxazol)) vlákna známe pod obchodným názvom Zylon®. Práve do PBO vlákien boli vkladané veľké nádeje vzhľadom na ich ohromujúce mechanické vlastnosti. Vplyv objemového zlomku vlákien na modulu pružnosti, pevnosť a ťažnosť kompozitov bol skúmaný. Experimentálne zistený modul pružností bol porovnaný so semi-empirickým Halpin-Tsai modelom. Prídavok sklenených a uhlíkových vlákien viedol k značnému zvýšeniu modulu pružnosti. Ukázalo sa, že po istej hodnote objemového zlomku dochádza k poklesu pevností kompozitov v dôsledku zvyšujúceho sa počtu defektov. Prídavok PBO vlákien preukázal len nepatrný vystužujúci efekt. Viskoelastické vlastností kompozitov boli skúmané pomocou dynamicko mechanickej analýzy (DMA). Termogravimetrická analýza (TGA), konfokálna laserová rastrovacia mikroskopia (CLSM) a rastrovacia elektrónová mikroskopia (SEM) boli využité k štúdiu štruktúry kompozitov.
Physicochemical and structural analysis for characterization of native and modified humic acids
Solanský, Pavel ; Sovová, Šárka (referee) ; Enev, Vojtěch (advisor)
This bachelor thesis is focused on structural and physicochemical characterization of native and methylated humic acid. These samples of humic acids, which were isolated from oxidized brown coal Leonardite, were characterized by thermal and spectrometric methods. The following analytical techniques were selected to determine the structural and physico-chemical changes between native and methylated humic acid: thermogravimetry (TGA), elemental analysis (EA), molecular absorption spectroscopy (UV/Vis), Fourier transform infrared spectroscopy (FTIR), fluorescence spectroscopy and last but not least nuclear magnetic resonance (13C NMR). The aim of this bachelor thesis was to find the differences in the structure of selected humic acids and also to verify the suitability of the techniques, which were used to characterize these biocolloid substances.
Isolation and fractionation methods for determination of humic substances content in South Moravian lignite
Černý, Pavol ; Kalina, Michal (referee) ; Enev, Vojtěch (advisor)
This bachelor thesis focuses on isolation and fractionation of humic substances (HS) from the natural matrix of lignite, which comes from southern Moravia from the mine Mír Mikulčice. In the theoretical part, it informs the reader about the issue, starting with information about lignite and HS. In this work, the standard procedure of isolation and fractionation of HS was used as according to the International Humic Substances Society (IHSS). The content of HS in the natural matrix of lignite was determined, and then isolated HS were subjected to physicochemical characterization – elemental analysis (EA), thermogravimetric analysis (TGA), UV/Vis spectrometry, infrared spectrometry with Fourier transformation (FTIR) and the acidity of humic acids (HA) was determined by potentiometric titration. EA was used to detemine the content of biogenic elements, moisture and ash content were determined by TGA. By using FTIR, various functional groups and building blocks that are present in supramolecules of HS were indentified and absorption coefficients EET/EBT, E2/E4, E2/E3 a E4/E6 were determined by UV/Vis spectrometry. Results represent good characterization of HS isolated from lignite and are in agreement with scientific literature.
Ultrafine combustion particles
Sitek, Tomáš ; Skála, Zdeněk (referee) ; Skála, Zdeněk (referee) ; Pospíšil, Jiří (advisor)
This diploma thesis deals with issues of fine and ultrafine particles formation during thermal decomposition and combustion of biomass. An introduction is devoted to a utilization of biomass as fuel. A following part describes the gas products emerging generally during combustion process. A current emission and air pollution situation in the Czech Republic as well as the health impacts of solid pollutants on human are also mentioned. Within an experimental measurement three basic factors that have impact on fine particles formation during combustion of beech wood (i. e. oxygen content in combustion atmosphere, type of the sample and size of the sample) were thoroughly analyzed. Attention was paid to a progress of thermal decomposition and combustion of sample with respect to the particles formation. Finally, a measurement of fine particles amount was accomplished in a real boiler successively with four different biomass pellet types.
Hydration of biocolloids - calorimetric study
Šméralová, Ester ; Pekař, Miloslav (referee) ; Klučáková, Martina (advisor)
Presented master's thesis focuses on the study of hydration of selected biocolloid substances, specifically humic substances (humic acids and fulvic acids), hyaluronic acid with three different molecular weight, chitosan and dextran. Interaction of biocolloids with water was studied by different methods. The effect of solubility, structure, functional groups in molecule on sorption and hydration ability of these biocolloids was investigated. In the case of hyaluronan the influence of molecular weight was also study. Differential scanning calorimetry DSC and perfusion calorimetry give results of heat of hydration, enthalpies and temperature of crystallization and melting. Thermogravimetric analysis TGA was used to determine the original moisture content of the samples.
Mechanical propertties gel polymer aprotic electrolytes
Bárta, Vladimír ; Musil, Michal (referee) ; Sedlaříková, Marie (advisor)
This work deals with the measurement of electrical conductivity and mechanical properties of gel polymer electrolyte containing Lithium ion and their preparation. The theoretical part deals with the development of gel polymer electrolyte, their use and methods of measurement of electrical conductivity and mechanical properties. In the experimental part describes the preparation of gel electrolyte, the measurement of electrical conductivity, temperature dependence and the measurement of mechanical properties.

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