|
| |
|
|
Preparation and application of nanoparticles and nanofibres with natural UV filters
Plachá, Monika ; Skoumalová, Petra (referee) ; Márová, Ivana (advisor)
The presented diploma thesis is focused on preparation of nanoparticles and nanofibres with natural UV filters. Liposomes with encapsulated aqueous, ethanol and lipid extracts were prepared. Nanofibers from PHB containing lipid extract were prepared too. As a part of this work, an overview of natural sources with potential effects as UV filters were introduced. Moreover, nanoparticles and nanofibers and methods of their characterization were described. Size, polydisperse index and colloid stability of prepared nanoparticles were characterized via DLS. In experimental part aqueous, ethanol and lipid extracts were prepared from roasted coffee, green coffee and cascara. These extracts were spectrophotometrically characterized for the content of polyphenols, flavonoids, antioxidant activity, tannins and their SPF. Liposomes and liposomes containing PHB with these extracts were prepared and the encapsulation effectivity, short–term and long–term stability as well as SPF of nanoparticles were determined. Nanofibers from PHB containing lipid extracts were prepared via electrospinning and forcespinning methods. Prepared nanofibers were examined via FTIR–ATR. Antioxidant activity, short–term and long–term stability were determined spectrophotometrically. From selected nanoparticles, emulsions and gels were prepared and their SPF was also determined. Three types of emulsions with the best SPF were selected and tested on volunteers. Sedimentation stability of emulsions was tested by analytical centrifuge. Finally, cytotoxicity of selected nanoparticles and nanofibers was tested via MTT assay using human keratinocytes.
|
|
|
Stability problems study of framed structures
Piják, Jiří ; Vlk, Zbyněk (referee) ; Zídek, Rostislav (advisor)
In the first chapter the problem of ideal member, member with initial curvature and meaning of Euler’s critical force is regarded. Parameters of stability, mainly calculation of critical loading and buckling lengths, are studied in the second part. The same part contains comparison of results of computational programs and mechanical approach. Next attention is paid to imperfections, to possibilities of determination and comparison of results on a simple member. Comparison of possible judgements of buckling on a simple beam and on frames according to ČSN EN 1993-1-1 is performed on the final part.
|
|
|
Analysis of Logistic Maps
Adeleke, Joshua Owolabi ; Šremr, Jiří (referee) ; Řehák, Pavel (advisor)
Logistická mapa souvisí s diskrétní logistickou rovnicí. Na rozdíl od svého kontinuálního protějšku vykazuje logistická diferenční rovnice velmi komplikovanou dynamiku včetně chaotiky chování. Tato práce tak zkoumala kvalitativní chování logistické mapy podle pomocí některých matematických nástrojů. Tato dynamika byla studována systematicky, a to tak, aby její povaha byla čistá forma až do bodu, kdy bylo komplikované se s ní vypořádat, byly pečlivě studovány. dále pojem konjugace byl zaměstnán v okamžiku, kdy jeho analytický výpočet představoval být komplikovaný, s čímž byly dále odhaleny jeho vlastnosti. Byly učiněny pozoruhodné závěry, mezi nimiž je popis chaotického chování logistická mapa, jak ji odhaluje její spojení se stanovou mapou. V průběhu této studie tedy existuje další nástroj pro vyšetřování chaotického chování byla poznamenána logistická mapa, která je symbolickou dynamikou, se kterou se bude v budoucnu studovat logistická mapa může zabrat.
|
|
|
Design of electrical travel of reaper`s drive unit
Otoupalík, Jan ; Černý, Michal (referee) ; Koutný, Daniel (advisor)
This bachelor thesis focuses on the design of electrical travel for universal mowing machine, which will be controlled remotely. Designed travel has independent wheel drive, the maximum speed of 10 km per hour and can be used in the terrain with a slope of 30°. The thesis deals with the determination the parameters of the travel, design of the possible electrical drive units and design with respect to the stability of the device. Another part of the thesis deals with the design of the travel and describes particular parts of the travel.
|
|
|
Decomposition and stability of organic matter in soil
Tabaková, Eva ; Enev, Vojtěch (referee) ; Klučáková, Martina (advisor)
In the soil, the plant material is decomposed by several factors. In the process, one part of the carbon returns to the atmosphere as carbon dioxide, whereas another part is stabilised in the soil. The aim of this study is decomposition and stability of organic matter in soil using a simple and innovative TBI method. Through this method, we examined the weight change after the incubation period of 90 days, where biomass of green tea was degraded in cambodia soil. Tea bags have provided us with valuable information on the decomposition and amount of carbon in the soil, because the biomass itself is of organic origin. This information is based on the fact that the soil and the decomposition processes have a direct impact on the change in climatic conditions. Thanks to further analytical methods, elemental analysis, thermogravimetric analysis and infrared spectroscopy with Furier transformation, was found indispensable information about tea composition.
|
|
|
Extension of Centrifugal Compressor Operational Stability
Růžička, Miroslav ; Třetina, Karel (referee) ; Kmoch, Petr (referee) ; Klement, Josef (advisor)
Centrifugal compressors with high pressure ratio are widely used in small aircraft turbine engines and turbocharges. At high rotational speeds they have narrow stable operating region and commonly used impellers with back swept blades are not able to ensure requested stability. In order to achieve wider stable operating region, some other anti-surge measures can be used, such as an Internal Recirculation Channel (IRC) located in compressor impeller inlet. This thesis deals with an investigation of IRC influence on centrifugal compressor operational parameters. As a first, the various recirculation channel geometry was studied by using of CFD analysis on simplified computational models. Those geometry, which indicated best results in terms of mass flow and looses in channel were used for testing on a model test device. Subsequently the same geometry was tested on real centrifugal compressor in experimental turbine engine to verify influence of IRC on compressor performance map – pressure ratio and efficiency. Simultaneously the CFD analyses of IRC with a 3D model of compressor impeller were performed and results compared with those, gained from measurement on model and compressor. In addition the measurement of flow field downstream the recirculation channel outlet slot with using of 3-hole pressure probe was performed and compared with flow velocity profiles evaluated from numerical simulations.
|
|
|
Steel Structure of Observation Tower
Klimeš, Pavel ; Šmak, Milan (referee) ; Hron, Lukáš (advisor)
The bachelor thesis concerns with the design and static analysis of the lookout steel construction, which has the height of 25 m and is situated in the Žabčice location. The technical report and drawings are included in the thesis as well. The aim of the thesis was to determine the lookout total load (including permanent, live and climate loads), its implementation in the computer software SCIA Engineer 2012.0 and to perform the stress analysis of selected rods, joints and anchorages by means of the manual calculation. The author of the thesis focused on the climatic load due to wind and ice accretion, which was determined with the use of two approaches according to standards ČSN EN 1991-1-4, ČSN EN 1993-3-1 a ČSN ISO 12494. Both the approaches were evaluated and for the less favorable one the static analysis was carried out.
|
|
|
Linear difference equations: stability analysis
Tesař, Lukáš ; Dosoudilová, Monika (referee) ; Tomášek, Petr (advisor)
This thesis deals with asymptotic stability investigation of linear difference equation. The Schur-Cohn criterion and discrete Routh-Schur criterion are introduced and demonstrated on several examples. Both criterions are implemented in Maple programming enviroment. Boundary locus technique is illustrated on a stability analysis of the Adams-Bashforth method for numerical solving of an initial value problem of first order ordinary differential equation.
|
|
| |
guest ::
