National Repository of Grey Literature 17 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Spatially separated HOMO/LUMO at interface of polypyrrole physisorbed on oxidized nanodiamond facets
Matunová, Petra ; Jirásek, Vít ; Rezek, Bohuslav
Nanodiamond particles (NDs) have recently risen in popularity owing to their unique and perspective properties. Merging NDs with organic molecules, such as polypyrrole (PPy), into hybrid organic-semiconductor functional systems gives rise to potential applications in photovoltaics (PV), which is supported by prior experimentally observed charge transfer between bulk diamond and PPy. This work focuses on the most relevant (111) and (100) O-terminated ND facets with different coverage of surface terminating oxygens in ether, epoxide, ketone, and peroxide positions. We use density functional theory (DFT) computations employing B3LYP functional and 6-31G(d) basis set. Energetically the most favorable oxidized ND facets were further optimized with PPy in physisorbed configurations. Analysis of geometry, binding energy, HOMO-LUMO gap, and charge transfer was done on the relaxed PPy-ND structures. Multiple hydrogen bonds are formed between PPy amino groups and O atoms on ND surface.
The intrinsic submicron ZnO thin films prepared by reactive magnetron sputtering
Remeš, Zdeněk ; Stuchlík, Jiří ; Purkrt, Adam ; Chang, Yu-Ying ; Jirásek, Vít ; Štenclová, Pavla ; Prajzler, V. ; Nekvindová, P.
The DC reactive magnetron sputtering of metallic target in oxide atmosphere is a simple method of depositing the intrinsic (undoped) nanocrystalline layers of metal oxides. We have optimized the deposition of the intrinsic ZnO thin films with submicron thickness 50-500 nm on fused silica glass substrates and investigated the localized defect states below the optical absorption edge down to 0.01 % using photothermal deflection spectroscopy from UV to IR. We have shown that the defect density, the optical absorptance and the related optical attenuation in planar waveguides can be significantly reduced by annealing in air at 400 °C.
Nursing care of the patient with ischemic heart disease
Šedová, Lenka ; Heřmanová, Jana (advisor) ; Jirásek, Vít (referee)
Autor práce: Lenka Šedová Vedoucí práce: Mgr. Jana Heřmanová Odborný konzultant: MUDr. Vít Jirásek Téma práce: A Nursing Care of the Patient with Diagnosis Coronary Artery Disease after Surgery Abstract: The aim of the work is to report on the case of a 79-year-old patient after cardiac surgical intervention. The surgery was indicated for coronary artery disease. The clinical part deals with the characteristics and stages of ACD. It also deals with the diagnosis and treatments of UP (unstable angina). The next part describes the patient's hospitalization. The last part describes the palliative care of this patient, his psychological rehabilitation and his return to daily life. The nursing history is formulated according to the theory of Virginie Henderson. An important role in the reduction of complications is the education of patient. Key words: ACD, UA, nursing proces, Henderson's theory, aortocoronary bypass, Warfarin, methods of invstigation, self-sufficiency, self-care
Calculations of nanocrystalline diamond-covered waveguides based on amorphous silicon
Jirásek, Vít ; Prajzler, Václav ; Remeš, Zdeněk
Nanocrystalline diamond (NCD) coatings on planar waveguides (WG) in the IR region allow to design optical sensors sensitive to absorbers like proteins or other biomolecules. In this contribution, we present a 2D model of a multi-layer WG developed under FEM (finite element method) simulation software Comsol Multiphysics. The model is based on the modified wave equation solved in the frequency domain and includes optical absorption. It was found that for the single-mode WG working in the narrow region of 1550-2000 nm the silicon thickness must be 150-320 nm. It was found that in order to keep a reasonable signal attenuation, the NCD film must be prepared with the optical absorption coefficient lower than 10 cm-1, being a rather challenging task. Dependencies of the signal attenuation on the NCD film thickness, absorbing layer height, its absorption coefficient and exciting wavelengths are presented.\n
General methodology for high temperature processes of semiconductor technology by the finite element methods
Jirásek, Vít ; Potocký, Štěpán ; Sveshnikov, Alexey
A general methodology for modeling of high-temperature reactors produced by SVCS Process Innovation, Ltd., using the finite element, resp. finite volume method, was developed. The methodology covers basics principles of working with SW packages for CFD modeling with the emphasis on the strongly coupled processes of chemically reacting fluid flow, mass and heat transport. An important part is devoted to the model-experiment relationship, verification and validation of models and comparison with experiments.
Interpretation of the C=O band of modified diamond nanoparticles by means of DFT theory
Jirásek, Vít ; Kozak, Halyna ; Remeš, Zdeněk ; Kromka, Alexander
Diamond nanoparticles (DNPs) are an interesting class of nanomaterials, which has many unique properties. Their applications in medicine and molecular biology have been mentioned. The DNPs were reviewed in sense of their surface chemistry and a range of analytic techniques was pointed out. The experimental analysis can be enhanced by theoretical models based on the first principles. An approach to theoretical analysis of infrared spectra was introduced. As an example, a part of FTIR spectra of the oxidized DNPs was interpreted by means of the DFT theory. The calculation of the C=O stretch vibrational frequencies of carboxylic and anhydride groups on certain model clusters enabled to explain the shift and splitting of the measured spectral bands.
Produkce atomárního jódu
Picková, Irena ; Jirásek, Vít ; Schmiedberger, Josef
In this article we describe our new experimental device for generation of atomic iodine in discharge for a COIL (chemical oxygen-iodine laser) and also DOIL (discharge oxygen-iodine laser) systems. For the new discharge method of atomic iodine generation, we are going to use the optical emission spectroscopy diagnostics, by which we will detect species present in plasma and use this information for optimization of iodine generation process.
Úprava počítačové mříže a výběr interpolačního schématu při řešení supersonického míchání proudícího prostředí
Jirásek, Vít
The injection of diluted iodine into the supersonic flow of helium was studied by means of CFD software Fluent. The computational grid was subsequently adapted, i.e. refined in the selected regions with large gradients of different defined quantities. A sensitivity of the refinement on the local and far-field solution was obtained. A sensitivity of the flowfield on the replacement of the first order interpolation scheme to the second order one in several combinations of solved equations was done. An influence of the increasing the interpolation scheme order on the far-field was found, dependent on the way of combination of the 1st and 2nd orders in selected equations interpolation.

National Repository of Grey Literature : 17 records found   1 - 10next  jump to record:
See also: similar author names
3 Jirásek, Vojtěch
2 Jirásek, Václav
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