National Repository of Grey Literature 73 records found  1 - 10nextend  jump to record: Search took 0.02 seconds. 
Chemical sensor for the quality of the protective atmosphere of packaged foods
Filipi, Denisa ; Čeppan, Michal (referee) ; Veselý, Michal (advisor)
This thesis deals with optimizing compositions to prepare thin films for the quality sensor of the protective atmosphere of packaged food. This sensor is based on the detection of oxygen ingress into a modified atmosphere food package using a colour change of the sensor. Titanium dioxide dispersion was used as semiconductor and glycerol as sacrificial electron donor. The effect of the polymer matrix on the prepared thin films's appearance and on the reduction and reoxidation rates of the films was investigated. The thickness and rheological parameters of the selected sensor mixture were characterized and the stability of the thin films under visible light was monitored. The effect of oxygen concentration on the sensor's reverse oxidation kinetics was also studied. Furthermore, the selected sensor mixture print conversion from laboratory to operational scale was carried out. The prepared sensor thin films can be reduced by UV radiation with an intensity of 0.4 mW·cm2 in 35 s, and the color response of the film is visible even at low oxygen concentrations.
Material printing upscaling of chemical sensors to R2R techniques
Fanglová, Michaela ; Krystyník, Pavel (referee) ; Veselý, Michal (advisor)
The main task of the diploma´s thesis was to prepare mixtures for printing ozone and UVB sensors. Subsequently, to optimize the compositions and rheological properties of these mixtures for the preparation of chemical sensors for printing by production R2R machnies, including their calibration to detect required doses of ozone and UVB radiation. The experimental study focoused on the laboratory preparation of mixtures for chemical sensors and their subsequent conversion and printing on semi-operational and production R2R machines. The transfer of production to a larger scale was achieved through changes in the rheological properties of the compositions. The prepared ozone sensors were exposed to different ozone doses and their color change was monitored as a function of the ozone dose. The UVB sensors were calibrated to the required UVB dose and their colour response to the UVB dose was monitored.
Self-cleaning ability of organic photo-active layers
Těthal, Vít ; Vala, Martin (referee) ; Veselý, Michal (advisor)
In this paper, methodes of determination of singlet oxygen (decolorization methodes, luminiscence detection, reaction with anorganic compounds, electon paramagnetic resonation, detecting of singlet oxygen luminiscence, detecting of absorption in IR region) and determination of efectivity of photoactive layers (photobleaching of dye aqueous solution, photodegradation of a solid fatty deposit, photoreduction of an organic dye, photooxidation of sodium salt of terephtalic acid, degradation of 1,3-diphenylisobenzofuran (DPIBF), degradation of diketopyrrolopyrrole (DPP), degradation of acridine orange) are summarized, including principle and procedure. In experimental part, 2 of these methodes (DPIBF and DPP degradation) were chosen and tested. Reaction rate constant and conversion were measured. It was found out that DPIBF methode is quick, reliable and reproducable.
Kinetics of photocatalytic and electrophotocatalytic degradation of swimming pool water model pollutants
Morávková, Eva ; Cihlář, Jaroslav (referee) ; Veselý, Michal (advisor)
This diploma thesis deals with the coating and printing of thin layers based on nanoparticles of titanium dioxide and organosilica binder on various substrates. The influence of the ratio of the both components on the activity of the prepared immobilized layers was studied. Five compositions with different ratios of TiO2 and binder were prepared. The work focuses mainly on the study of photocatalytic and photoelectrocatalytic properties of prepared layers. It was also important to characterize the mechanical properties of the layer such as hardness or adhesion. Both photocatalytic and photoelectrocatalytic activity were determined by monitoring the degradation of the model pollutants in aqueous solutions. The dye Acid Orange 7 and UV filter 2-hydroxy-4-methoxybenzophenone were used in conjunction with UV/VIS spectroscopy or high performance liquid chromatography techniques. Both photocatalytic and photoelectrocatalytic activity were expressed using kinetic characteristics.
Spectral analysis of chemical code
Šimončičová, Monika ; Ďurovič, Michal (referee) ; Veselý, Michal (advisor)
The diploma thesis deals with the study of the process of grinding aggregates of particles of a mixture of powdered lanthanide oxides in the dowanol solvent. The formed dispersions were characterised and used for the preparation of printing inks and subsequently for the printing of labels with chemical codes readable by XRF spectrometry. The aim was to study the milling process, to verify the reliability of reading and recognition of marks with the appropriate codes and to monitor the influence of the additive of the up-conversion powder on the resulting relative intensities of the elements in the chemical code. The statistical significance of the differences in the averages of relative intensities was assessed based on the Student's t test.
Photocatalytic sensor of oxygen
Filipi, Denisa ; Kubáč,, Lubomír (referee) ; Veselý, Michal (advisor)
This bachelor thesis deals with the optimization of inks for the preparation of photocatalytic oxygen indicator.The aim was to prepare a photocatalytic oxygen indicator with sufficient colour change after photoreduction and after reverse photooxidation.The indicator is based on semiconductor particles (TiO2), a sacrificial electron donor, a redox dye and a polymer which serves as a binder. The effect of the polymer used on the appearance of the prepared layers deposited on the PET film was investigated. The effect of the concentration of sacrificial electron donor on the rate of photoreduction (transition to the colourless leuco form) and reverse photooxidation of the indicator (transition of the leuco form to the coloured form) was also studied. Based on the study of the indicators, the rate constants for photoreduction and photooxidation of the prepared indicators were determined.
Printed chemical sensors of UV light
Fanglová, Michaela ; Čeppan, Michal (referee) ; Veselý, Michal (advisor)
The main task of the bacherol´s thesis was to prepare a photosensitive layer reacting to the radiation dose with a color change. And to calibrate the prepared dosimeters to the required values of the radiation doses of the UVB radiation. This bacherol´s thesis is about light dosimeters, which are based on photochemical reactions. These reactions take place in a thin polymer layer. The experimental study focoused on the preparation and application of photosensitive compositions. These prepared dosimeter compositions were exposed to different doses of UVB radiation, where the color response to the exposure was monitored.
Optimization of chemical code printing with XRF identification
Uher, Tadeáš ; Ďurovič, Michal (referee) ; Veselý, Michal (advisor)
The Master’s thesis deals with study printing and optimization of a chemical labels with a code readable by XRF technique. The study is focusing on the identifiability of components in chemical code through data analysis in the Origin program environment and reproducibility of the analysis. The responses of the XRF signal on real samples of historical documents were studied and possible interfering elements were identified. Based on these analyses, a recommendation was formulated for the method of evaluating the obtained data, code analysis and also for the composition of the printing formulation.
Preparation and testing of large titanium dioxide layers
Maršálek, Blahoslav ; Kočí,, Kamila (referee) ; Veselý, Michal (advisor)
The aim of this bachelor theses was testing of mechanical and photocatalytical properties on printing suspension with different composition of the titanium dioxide with organosilicate binder printed on the PET foil. The cross-cut test was used to evaluate mechanical properties of the printed film surface. The photocatalytic activity was tested by decomposition of the acid orange 7 as a model pollutant using the UV-VIS spectrophotometry. Based on the results from experiments, the formal rate constants and the parameters of the mechanical stability of surfaces were obtained. The results shoved, that there is a clear correlation between the rate of organosilicate and titanium dioxide – the more is titanium dioxide, the higher is photocatalytic activity, but lower mechanical stability of the printed surface, what is probably caused by covering of titanium reaction centers by organosilicate. Possibilities of enhancing photocatalytic efficiency of the titanium dioxide and organosilicate composition are also discussed in this thesis.
Hodnocení aberace půdy vybraného katastru kraje Vysočina
Veselý, Michal
Aberrations of soil can be understood as a deviation of soil properties from an average value. The aim of this bachelor thesis was to find out and evaluate the degree of aberrations in selected lands of cadastral area of Krumvald, the Highlands Region (Vysočina). Within the Comprehensive soil survey, which was held in June 1969, a total of six sampling probes were dug up. For the needs of my work, three soil probes were re-excavated and evaluated. From the KPP records, it was possible to trace the pH data, granularity, carbonate content, humus, etc. These properties were again determined and compared. After performing the analyses and comparing the results obtained with the results of the CSS survey, I have come to the conclusion, that the lands have been negatively affected by aberrations in most of the observed properties. The exception is the V2 probe, where a positive aberration of soil properties appeared.

National Repository of Grey Literature : 73 records found   1 - 10nextend  jump to record:
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