INHIBITION OF CANDIDA ALBICANS GROWTH ON SURFACES TREATED BY DIELECTRIC BARRIER DISCHARGE WITH VARIOUS BARRIERS

Discharges generating low temperature plasma at atmospheric pressure have the potential to treat surfaces biologically contaminated by organic matter in a non-destructive manner. We have been studying ways of inhibiting the growth of microorganisms with the use of dielectric barrier discharge (DBD) plasma. The effect of the choice of a barrier material and its thickness on thegermicide properties of the DBD is described. We used Saboraud agar inoculated by 105 cfu/cm2 of Candida albicans yeast as the model contaminated surface. After cultivation, the proportion of the treated surface with no C. albicans colony was evaluated

Optimisation of fuel cells module with proton exchange membrane

Diplomová práce se zabývá optimalizací parametrů svazku vodíkových palivových článků s otevřenou katodou a protonově výměnnou membránu. Během řešení optimalizace byla využita komerční sestava membránové elektrody (MEA) a následně byly připraveny dva prototypy pomocí ultrazvukové sprejové depozice a magnetronového naprašování. Hlavním cílem práce bylo dosažení stabilních pracovních podmínek, které byly odladěny na základě změn v geometrii a uspořádání rozvodných kanálků elektrod či přívodu vzduchu do katody. V teoretické části byly popsány typy palivových článků a jejich porovnání s redoxními průtokovými baterie. Byla popsána termodynamika a elektrochemie u dějů v palivových článcích.K řešení byly využity testovací stanice společnosti LeanCat na kterých byla využita metoda elektroimpedanční spektroskopie a měření polarizačních křivek. K přípravě vlastních MEA jsme využili zařízení Sono-tek, které naneslo katalyzátorový inkoust se složením nanočástic uhlíku a platiny. Druhý prototyp z magnetronového naprašovače nevyužívá nanočástice uhlíku, ale nekorozivní CeO2 na vyleptaném povrchu membrány. Následná vrstva naprášené platiny je několikanásobně menší než u komerčních produktů.Výstupem této práce je navržení funkčního, výkonného, jednoduchého a zároveň bezpečného svazku palivových článků. Dále porovnání proudových a výkonových hustot komerčních a vlastních MEA. Membrány s ultrazvukově nanesenou vrstvou katalyzátoru dosáhly vyšších výkonů, než je nominální hodnota výkonu uváděná výrobcem u komerčních MEA. Prototyp membrány s magnetronově naprašovánou vrstvou 0,1 mg/cm2 platiny položil dobrý základ pro budoucí vývoj MEA s nižším obsahem platiny v katalyzátoru.The aim of the master thesis is the optimisation of the fuel cells module with open cathode and proton exchange membranes. During the optimization commercial membrane electrode assembly (MEA) was used. We prepared two functional prototypes with catalyst by using ultra-sonic coating or magnetron sputtering. The main goal of the thesis is achieving stable working conditions which have been fine-tuned based on the changes of flow-field geometry and arrangement of air supply to the cathode. Types of fuel cells and their comparison to redox flow batteries are described in the theoretical part. Also, the thermodynamics and the electrochemistry of processes in the fuel cell is concluded.Test station made by the LeanCat company were used to create the electrochemical impedance and the polarization curves of the fuel cell. The preparation of first MEA prototype has been achieved by the Sono-tek device which was coated the Pt nanoparticles with carbon support on the surface of the membrane. Second prototype prepared by magnetron sputtering device does not use the carbon support. Instead of the carbon support there is a non-corrosive layer of CeO2 on the etched surface of the membrane. The subsequent sputtered layer of Pt is several times smaller than the one in the commercial products.The outcome of this work is a design of functional, powerful, simple and safe fuel cell module. Next is comparison of the current and power densities of the commercial and own MEA. The membranes that have ultra-sonic coated catalyst achieved better power results than a nominal power value that is declared by the commercial producer. The magnetron sputtered prototype with only 0,1 mg/cm2 of Pt laid a sufficient background for the future research of the MEA with a lower Pt loading in a catalyst layer

Constructional design of the automated functional model for bonding circular textile filters

60 s., 3 s. příl. :obr., ta., výkresy +sam. příloha +CD ROMV diplomové práci je popsán princip filtrace a základní druhy filtračních skládaných vložek. Jsou také popsány současné způsoby výroby filtračních vložek z textilního pásku a různé provedení spojení jejich konců. Dále je popsán automatický způsob výroby filtračních vložek z papírového pásku. V další části práce jsou podrobně rozebrány navrhované způsoby výroby filtračních vložek z textilního pásku a u vybrané varianty jsou detailně popsány jednotlivé operace, které zařízení vykonává. V závěru práce jsou provedeny kontrolní výpočty vybraných částí mechanizmu a vyhodnocení výsledků

Preparation of ion exchange foils by wet treatment

Cílem práce je vytvořit funkční membránu pro přenos vlhkosti, ale zároveň membránu nepropustnou pro jiné plyny. Materiál najde využití ve výměnících vzduchu nebo jako funkční membrána pro vojenské oblečení. Podobné membrány již vyrábí americká firma Kraton, která používá pentablokový kopolymer. Z infračervené analýzy byla zjištěna funkční skupina odpovědná za přenos vlhkosti, tato skupina je silně kyselá (sulfonová). Na základě tohoto poznatku bylo hlavní myšlenkou práce vytvořit homogenní ionexovou membránu se sulfonovou funkční skupinou anebo optimalizovat stávající ionex ionexové heterogenní membrány a jejich inertní pojivo pro dosažení podobné funkčnosti a podobných vlastností jako zmíněné kopolymerní pentablokové membrány. Membrány vyvinuté pro tuto práci jsou heterogenní ionexové fólie bez vyztužující textilie. Důležitými vlastnostmi sledované u ionexových fólií během výzkumu jsou ionexová kapacita, účinnost transportu a mechanická stabilita. Překvapivě výsledky vyvinutých membrán vykazují lepší vlastnosti než současně komerčně dostupné membrány. Na druhé straně mechanické vlastnosti, jako je teplota skelného přechodu, jsou stále výzvou pro další výzkum.The aim of this work is preparation of membranes efficient for moisture transport while impermeable for other gasses. The application of the material is in air conditioning or in functional membranes for army clothing. Such membranes have been already developed by US company Kraton and they are represented by pentablock copolymer membranes. Infrared analysis of this material revealed the sulphone functional group responsible for the moisture transport. The group is strongly acidic. So the idea was to develope homogenic ion exchange membrane with sulphonic group or to optimize the current ion exchange heterogeneous membranes and their inert binder to achieve similar functionality and similar properties as mentioned pentablock copolymeric membranes. The membranes developed in this work are heterogeneous ion exchange membrane foils without the arming textile. Important features of ion exchange foils monitored during the research are ion exchange capacity, efficiency of moisture transport and mechanical stability. Surprisingly the results of developed membranes exhibit better features than commercially available membranes. On the other hand the mechanical properties including glass transition temperature are still the challenge for following development

Force Effect of Supercritical Flow of Gases and Vapors on Profile Grating

Tato diplomová práce se zabývá problematikou nadzvukového proudění v kanálu s měnícím se průtočným průřezem. V kanálu se při aplikaci Lavalovy dýzy začnou tvořit rázové vlny. Při procházení rázových vln přes překážku se část kinetické energie rázové vlny přemění na energii tlakovou, která dokáže generovat silový účinek na danou překážku. Cílem diplomové práce je navržení měřícího standu, který by byl schopný takto generovaný silový účinek změřit a zaznamenat.This master thesis deals with the issue of supersonic flow in a canal with a changing flow cross-section. Shock waves start to form in the channel when the Laval nozzle is applied. When shock waves pass through an obstacle, part of the kinetic energy of the shock wave is transformed into pressure energy, which can generate a force effect on the given obstacle. The goal of the master thesis is to design a measuring stand that would be able to measure and record the force effect generated in this way.361 - Katedra energetikyvýborn

The onset of flysch sedimentation in the Kaoko Belt (NW Namibia) – Implications for the pre-collisional evolution of the Kaoko–Dom Feliciano–Gariep orogen

Detrital zircon provenance study of a metamorphosed sedimentary succession in the eastern part of the Kaoko Belt in Namibia has revealed two distinct sources for the Neoproterozoic sedimentation along the southwestern Congo Craton margin. The lower part of the succession shows detrital zircon ages consistent with erosion of Paleoproterozoic basement of the Congo Craton with an inferred Mesoproterozoic volcano-sedimentary cover. Within the middle part of the succession, which includes glaciogenic sediments correlated with the Sturtian (717–660 Ma) glaciation, the Mesoproterozoic zircon grains disappear and the signal is dominated by ages known from the Congo Craton basement. The sedimentation in these parts of the succession is interpreted as related to the early Neoproterozoic rifting. The sedimentary rocks in the top part of the profile contain only subordinate proportion of the Paleoproterozoic–Archaean zircon grains and the populations are dominated by three age groups of ca. 1.0–1.2 Ga, ca. 800–750 Ma and ca. 650 Ma, consistent with erosion of the Punta del Este–Coastal Terrane exposed in the centre of the Kaoko–Dom Feliciano–Gariep orogen. An associated glaciogenic horizon interpreted as reflecting the Marinoan (645–635 Ma) glaciation constrains the sedimentation in the upper part of the succession and suggests a short time span between the high-grade metamorphism/magmatism in the Punta del Este–Coastal Terrane and its exhumation. Sedimentary rocks with such detrital zircon pattern appear also in the Damara and Gariep belts. Their source in the western part of the Kaoko–Dom Feliciano–Gariep orogen suggests that they represent an early orogenic flysch that originated during early collision in the western part of the orogen. The short time span between the metamorphism/magmatism in the Punta del Este–Coastal Terrane and deposition of the early orogenic flysch derived from it suggests that the Coastal Terrane was never separated from the Congo Craton by an oceanic domain. The estimated time span between the end of lithospheric stretching and sedimentation of the early flysch suggests that the hypothetical Adamastor Ocean separating the western and eastern forelands of the Kaoko–Dom Feliciano–Gariep orogen must have been small.acceptedVersio

Internal flow and air core dynamics in simplex and spill-return pressure-swirl atomizers

[EN] It is well known that the spray characteristics of pressure-swirl atomizers are strongly linked to the internal flow and that an unstable air core may cause instabilities in the spray. In this paper, a 10:1 scale transparent Plexiglas (PMMA) model of a pressure-swirl atomizer as used in a small gas turbine is introduced. The internal flow was examined using high-speed imaging, laser-Doppler anemometry and computational fluid dynamics tools. The experimental and numerical results were analysed and compared in terms of the air core morphology and its temporal stability. Two different liquids were used, Kerosene-type Jet A-1 represented a commonly used fuel while p-Cymene (4-Isopropyltoluene) matched the refractive index of the Plexiglas atomizer body. The internal flow characteristics were set using dimensionless numbers i.e. the Reynolds number and Froude number. The flow test conditions were limited to inlet Reynolds numbers from 750 to 1750. Two atomizers were examined to represent a Simplex and Spill-return (SR) geometries. In a comparative manner, the SR atomizer features a central passage in the rear wall of the swirl chamber. The main advantage of this concept is that the fuel is always supplied to the swirl chamber at a high pressure therefore providing good atomization over a wide range of the injection flow rate. However, the presence of the spill orifice strongly affects the internal flow even if the spill-line is closed. The air core in the Simplex atomizer was found fully developed and stable. The SR atomizer behaved differently, the air core did not form at all, and the spray was therefore unstable.This work has been supported by the project No. GA15-09040S funded by the Czech Science Foundation and the project LO1202 NETME CENTRE PLUS with the financial support from the Ministry of Education, Youth and Sports of the Czech Republic under the "National Sustainability Programme I" and project Reg. No. FSI-S-17-4444 funded by the Brno University of Technology.Maly, M.; Janáčková, L.; Jedelský, J.; Sláma, J.; Sapík, M.; Wigley, G. (2017). Internal flow and air core dynamics in simplex and spill-return pressure-swirl atomizers. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 233-240. https://doi.org/10.4995/ILASS2017.2017.4995OCS23324

Detrital zircon U-Pb and Hf constraints on provenance and timing of deposition of the Mesoproterozoic to Cambrian sedimentary cover of the East European Craton, Belarus

International audienceThe sedimentary cover of the East European Craton (EEC) is unique because of its low degree of diagenetic alteration that allows preservation of the original “source to sink” relationships. The present study provides U-Pb and Hf zircon data for the entire Proterozoic sedimentary section of the EEC based on samples from five boreholes in Belarus within the Volyn-Orsha Basin, one of the most important sedimentary basins of the craton. Twenty-one samples of mudstones and sandstones were selected for detrital zircon U-Pb geochronology, supplemented by the Hf isotope analyses of zircons from 6 samples representing different U-Pb age spectra and bulk rock XRD mineralogy of all mudstone samples collected from the studied boreholes. Five clastic successions in the Volyn-Orsha Basin are characterized by different sources of detrital material: (1) The Mesoproterozoic Pinsk Suite with a narrow population of c. 2.0 Ga zircons, (2) The Orsha Suite with a broad 1.3–3.2 Ga zircon age distribution, (3) Glacial sediments of the Vilchitsy Series with an age spectra similar to the Orsha Suite, except for a c. 1.0 and 1.2 Ga cluster, (4) The Volyn and Valdai Series, including lowermost Cambrian, with a narrow trimodal population of 0.5, 1.5, and 1.8 Ga zircons, and (5) lower Cambrian (?) sediments with a diffused zircon age spectrum, including a 500–700 Ma cluster. Maximum depositional ages were constrained for the Vilchitsy Series at 977 ± 6 Ma and for the Volyn Series at 579–545 ± 4 Ma. Combined Hf zircon data indicate four episodes of new continental crust generation at 3.3, 2.8, 2.1–2.3 and 1.8 Ga, suggestive of source terrains within the crust of the present-day EEC. These sources experienced subsequent reworking of crust at c. 1.8 Ga and 550–600 Ma. Only a lower Cambrian sample lacks any trend or clustering within the Hf data probably due to mixing of zircons from exotic and local sources. Paleogeographic models explaining these provenance signals in terms of intracratonic erosion and sediment transport are presented