Jana Jurmanová - Academia.edu (original) (raw)

Papers by Jana Jurmanová

Physics Education, 2013

In this paper an experiment studying Planck radiation law is presented. The spectra of a heated f... more In this paper an experiment studying Planck radiation law is presented. The spectra of a heated furnace and of a halogen lamp under various conditions were measured with a small USB grating spectrometer and fitted with a Planck law. The temperature determined from the fit was then compared with the results of comparative temperature measuring techniques (e.g. with the measurement of filament temperature from the temperature dependence of filament resistance). We have shown, that even spectrometers with limited wavelength range may be successfully used to study Planck distribution. The temperature obtained from the fit of Planck law to the measured spectra was within the uncertainty close to the results of comparative techniques.

CCD kamera byla použita k vizualizaci Youngova experimentu v bilem světle. Specialni program byl ... more CCD kamera byla použita k vizualizaci Youngova experimentu v bilem světle. Specialni program byl vyvinut pro snadnou manipulaci, zobrazeni obrazu a výpocet intenzitniho profilu. Vypoctený intenzitni profil byl použit pro přibližne urceni vlnove delky světla filtrovaneho a snimaneho CCD kamerou.

The aim of this work was to study the low-cost plasma jet by optical methods. The plasma jet was ... more The aim of this work was to study the low-cost plasma jet by optical methods. The plasma jet was generated in surface barrier discharge configuration in argon by AC voltage of 11 kHz. The discharge was investigated by oscilloscopic measurements of discharge voltage and current and by spatially and temporally resolved optical emission spectroscopy. The investigations revealed a complicated development of discharge intensity, consisting of many discharge filaments. The large differences were observed between both polarities and among emissions of various species in the discharge. The obtained results provides better understanding of this plasma source and may be used for optimization of the configuration for specific applications (surface treatment, plasma sterilization etc.)

Přispěvěk podava zakladni informace o tradicnim každorocnim soustředěni studentů střednich skol.

In the present work, a decomposition of ethanol vapours in microwave plasma torch discharge at at... more In the present work, a decomposition of ethanol vapours in microwave plasma torch discharge at atmospheric pressure conditions was investigated. The discharge was driven by a microwave generator set to standard frequency of 2.45 GHz, using microwave power from 140 to 350 W. Microwave line was terminated with an exchangeable dual channel carbon nozzle, allowing us to separately sustain the plasma by argon gas (220 - 920 sccm) flowing through the central (axial) channel and initiate synthesis by introduction of ethanol vapours (4 - 20 sccm) carried by argon (300 – 1400 sccm) through secondary channel (annulus). Ethanol molecule provides appropriate ratio of C, H and O atoms for graphene nanosheet synthesis. Disrupting the balance by addition of small amount (1 – 10 sccm) of molecular admixtures (O2 and H2), we were able to study the crucial parameters governing the assembly of carbon species into preferred graphene nanosheet structures. Optical emission spectroscopy (OES) was used to ...

Natural leather was plasma treated with Diffuse coplanar surface barrier discharge (DCSBD) at atm... more Natural leather was plasma treated with Diffuse coplanar surface barrier discharge (DCSBD) at atmospheric pressure. The aim of plasma treatment was activation of leather surface and improvement of wettability. Samples of bovine leather were plasma treated for few seconds and analyzed with SEM, XPS, and contact angle measurement. Surface morphology was not affected with plasma treatment. Plasma treatment caused wettability change at the half value of contact angle in comparison with untreated leather. Wettability change is relative stable in the first 24 h after plasma treatment. Change in percentage of chemical bonds containing carbon and oxygen was observed.

Last decade two-dimensional carbon-based nanostructures such as graphene nanosheets, nanoribbons ... more Last decade two-dimensional carbon-based nanostructures such as graphene nanosheets, nanoribbons and carbon nanowalls have attracted much research interest, due to their remarkable properties combining high mechanical strength and flexibility, exceptional electronic and thermal conductivity, high carrier mobility and optical transparency. Potential application in different fields of science and technology include hydrogen and energy storage, reinforcement of polymer composites, electronics, electrochemical devices, or gas sensors. Our deposition process reported in this work is based on injecting ethanol vapours through a microwave plasma environment, where decomposition of ethanol molecules takes place. We used microwave plasma torch discharge (2.45 GHz, ~200 W, Figure 1) operating at atmospheric pressure conditions to synthesize graphene nanosheets with rectangular shape and typical size of hundreds of nanometres. Argon flowing through the central channel of the nozzle was used as...

V teto praci byla zkoumana možnost syntezy dvourozměrných nanocastic grafenu v plynne fazi. Použi... more V teto praci byla zkoumana možnost syntezy dvourozměrných nanocastic grafenu v plynne fazi. Použili jsme mikrovlnný plazmový plazmový výboj (2,45 GHz, 210 W) pracujici za atmosferickeho tlaku za ucelem syntezy nanocastic uhliku s obdelnikovým tvarem a typickou velikosti stovek nanometrů. Výboj hořaku byl zapalen argonem proudicim přes centralni kanal trysky. Kapalný ethanol, jehož výpary byly vedeny k vypoustěni nosným plynem - argonem, byl vybran jako prekurzor. Směs ethanolu, argonu a kysliku nebo vodiku byla zavedena do výboje přes vnějsi kanal trysky. Rozklad etanolových par při specifických podminkach nanaseni vedl k synteze grafenových nanasek. Syntetizovaný material byl shromažděn na křemikovem substratu umistěnem v držaku vzorku, který byl umistěn několik centimetrů nad výbojem. Byl zkouman vliv různých množstvi kysliku nebo vodiku v plynne směsi na vlastnosti syntetizovaných grafenových nanasek. Takto připravene vzorky byly analyzovany skenovaci elektronovou mikroskopii, Ra...

Plasma Sources Science and Technology, 2021

Few-layer graphene nanosheets were synthesised from ethanol using a microwave plasma torch. The s... more Few-layer graphene nanosheets were synthesised from ethanol using a microwave plasma torch. The stability of the discharge permitted us to directly observe and analyse two distinctive structures—a plasma zone and an assembly zone. Important plasma parameters and insights into the chemical processes taking place in these zones were gained using optical emission spectroscopy and digital imaging for a set of experimental conditions. The results of the plasma diagnostics were then correlated with the synthesised material properties, mainly obtained from electron microscopy and Raman spectroscopy.

Plasma Processes and Polymers, 2021

Nanotechnology, 2021

Understanding underlying processes behind the simple and easily scalable graphene synthesis metho... more Understanding underlying processes behind the simple and easily scalable graphene synthesis methods enables their large-scale deployment in the emerging energy storage and printable device applications. Microwave plasma decomposition of organic precursors forms a high-temperature environment, above 3000 K, where the process of catalyst-free dehydrogenation and consequent formation of C2 molecules leads to nucleation and growth of high-quality few-layer graphene (FLG). In this work, we show experimental evidence that a high-temperature environment with a gas mixture of H2 and acetylene, C2H2, leads to a transition from amorphous to highly crystalline material proving the suggested dehydrogenation mechanism. The overall conversion efficiency of carbon to FLG reached up to 47%, three times as much as for methane or ethanol, and increased with increasing microwave power (i.e. with the size of the high-temperature zone) and hydrocarbon flow rate. The yield decreased with decreasing C:H ratio while the best quality FLG (low D/G–0.5 and high 2D/G–1.5 Raman band ratio) was achieved for C:H ratio of 1:3. The structures contained less than 1 at% of oxygen. No additional hydrogen was necessary for the synthesis of FLG from higher alcohols having the same stoichiometry, 1-propanol and isopropanol, but the yield was lower, 15%, and dependent on the atom arrangement of the precursor. The prepared FLG nanopowder was analyzed by scanning electron microscopy, Raman, x-ray photoelectron spectroscopy, and thermogravimetry. Microwave plasma was monitored by optical emission spectroscopy.

Applied Sciences, 2020

We present a novel method of surface processing of complex polymer-metal composite substrates. At... more We present a novel method of surface processing of complex polymer-metal composite substrates. Atmospheric-pressure plasma etching in pure H2, N2, H2/N2 and air plasmas was used to fabricate flexible transparent composite poly(methyl methacrylate) (PMMA)-based polymer film/Ag-coated Cu metal wire mesh substrates with conductive connection sites by the selective removal of the thin (~10–100 nm) surface PMMA layer. To mimic large-area roll-to-roll processing, we used an advanced alumina-based concavely curved electrode generating a thin and high-power density cold plasma layer by the diffuse coplanar surface barrier discharge. A short 1 s exposure to pure hydrogen plasma, led to successful highly-selective etching of the surface PMMA film without any destruction of the Ag-coated Cu metal wires embedded in the PMMA polymer. On the other hand, the use of ambient air, pure nitrogen and H2/N2 plasmas resulted in undesired degradation both of the polymer and the metal wires surfaces. Since...

Vacuum, 2020

This study targeted wettability and adhesion enhancement of polyamide (PA) foil surface by plasma... more This study targeted wettability and adhesion enhancement of polyamide (PA) foil surface by plasma treatment at atmospheric pressure. Volume dielectric barrier discharge (VDBD) and diffuse coplanar surface barrier discharge (DCSBD) were applied in ambient air using exposure times 0.25-2 s. Water contact angle (WCA) measurements proved that both plasma sources achieved significant wettability improvement of PA 6 foil surface immediately after treatment. However, the durability of this hydrophilic effect was much more pronounced with the DCSBD, compared to the VDBD. The lowest registered drop of WCA after DCSBD treatment was from the initial 65 • to 28 • , which even after one month of storage recovered only to 44 •. In contrast, the VDBD treatment at similar parameters resulted in the WCA increase from 45 • to 54 • already after the first day of ageing. The XPS analysis of oxygen-based polar functional groups incorporated onto the treated PA 6 surface proved higher efficiency of DCSBD plasma. Moreover, the degree of surface oxidation was raised by increasing DCSBD's input power. Tape peel test revealed adhesion improvement achieved only with DCSBD, which had a growing tendency with increasing exposure time and input power. SEM did not show any noticeable damage of surface after the applied plasma treatments.

Japanese Journal of Applied Physics, 2020

Inner surfaces of three samples (alumina and copper tubes, ozonizer) were treated by ozone. The s... more Inner surfaces of three samples (alumina and copper tubes, ozonizer) were treated by ozone. The surface reactions of oxygen and ozone were studied after this treatment. The surface reaction of gaseous molecular oxygen leads to fast ozone creation. The created ozone again reacts with surface, which leads to its destruction. These reactions can be explained as surface reactions between adsorbed oxygen atoms and molecules or as surface reactions of these adsorbed species with gaseous species.

NANOCON 2019 Conference Proeedings, 2020

The relation between plasma temperature and properties of graphene nanosheet layer deposited on S... more The relation between plasma temperature and properties of graphene nanosheet layer deposited on Si/SiO2 substrate by decomposition of ethanol in microwave plasma torch discharge at atmospheric pressure was investigated in dependence on delivered microwave power and gas flow rates. Plasma modelling was carried out using COMSOL Multiphysics software with delivered microwave power, gas flow rates and experimental reactor geometry as input parameters. Results of the heat flow and fluid dynamics modelling were compared with substrate temperature measured by thermocouple integrated in quartz tube substrate holder. The graphene nanosheets layer was characterized by SEM, Raman spectroscopy and 4-point probe method. The layers were severals tens of μm thick and their sheet resistance varied from 2 to 40 kΩ/sq. The properties of individual graphene nanosheets, 2D/G and D/G Raman band ratio, as well as the sheet resistance of their conductive network were correlated with the increase of plasma temperature with increasing microwave power. The substrate temperature increased linearly with delivered microwave power and the layer sheet resistance was decreasing with increasing microwave power and saturated at 2 kΩ/sq and D/G ratio of 0.6.

Diamond and Related Materials, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Polymers, 2019

Polyoxazolines are a new promising class of polymers for biomedical applications. Antibiofouling ... more Polyoxazolines are a new promising class of polymers for biomedical applications. Antibiofouling polyoxazoline coatings can suppress bacterial colonization of medical devices, which can cause infections to patients. However, the creation of oxazoline-based films using conventional methods is difficult. This study presents a new way to produce plasma polymerized oxazoline-based films with antibiofouling properties and good biocompatibility. The films were created via plasma deposition from 2-methyl-2-oxazoline vapors in nitrogen atmospheric pressure dielectric barrier discharge. Diverse film properties were achieved by increasing the substrate temperature at the deposition. The physical and chemical properties of plasma polymerized polyoxazoline films were studied by SEM, EDX, FTIR, AFM, depth-sensing indentation technique, and surface energy measurement. After tuning of the deposition parameters, films with a capacity to resist bacterial biofilm formation were achieved. Deposited fi...

Scientia in educatione, 2017

In the present Case Study we explore the comprehension levels of relativity theory in prospective... more In the present Case Study we explore the comprehension levels of relativity theory in prospective science teachers who take the introduction to physics lesson at the Faculty of Education. Special Theory of Relativity multimedia animation was used to illustrate basic relativistic consequences. The effect of it for learning was researched. In the research, a case study was used. Research data were obtained by interviews and using open-ended questions prepared by the researcher.