No (412)
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412
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Applications of self-assembled 2D polystyrene nanosphere arrays
Domonkos, Mária; Ižák, Tibor; Demo, Pavel; Kromka, Alexander
2014 - English
In this study nanosphere lithography (NSL) is demonstrated to be a low-cost, parallel and material independent fabrication process for creating periodic arrays of nanostructures using self-assembled nanospheres as templates. SA is the most feasible way to fabricate 2D or 3D colloidal crystals on large areas. After the mask preparation NSL uses different steps of plasma etching and deposition processes. The resulting patterned nanostructures have a wide range of applications in many important areas such as photonics, antireflection, surface wetting, biological and chemical sensing, solar cells, etc. This study focuses on an overview of applications of 2D colloidal crystals. First, structuring of substrate surfaces and the creation of various nano-objects (nanotips, nanopillars, nanocones) is shown. Next, direct growth of patterned structures (graphene nanomesh and diamond structures) is pointed out.
Keywords:
nanosphere lithography; nanostructuring; polystyrene microspheres; reactive ion etching
Available at various institutes of the ASCR
Applications of self-assembled 2D polystyrene nanosphere arrays
In this study nanosphere lithography (NSL) is demonstrated to be a low-cost, parallel and material independent fabrication process for creating periodic arrays of nanostructures using self-assembled ...
Photocatalytic activity of ZnxCd.sub.1-x./sub.S quantum dots in dependence on their composition
Praus, P.; Svoboda, L.; Hospodková, Alice; Mamulová-Kutláková, K.
2014 - English
ZnxCd1-xS quantum dots (QDs) with the different composition x were prepared by precipitation of Zn and Cd acetates with sodium sulphide from aqueous colloid dispersions. Transition energies of these QDs were determined from UV-VIS spectra of the QDs colloid dispersions and consequently used for calculation of the QDs sizes according to the Schrödinger equation. The ZnCdS QDs size was found to be significantly influenced by their composition, decreased with increasing the Zn content. The QDs were also characterized by TEM, X-ray powder diffraction and PL. The photocatalytic activity of the QDs was studied using the methylene blue decomposition under UV irradiation with the maximum intensity of 365 nm. Different photocatalytic activity depending on the composition x was observed. Quantum levels of the QDs have important influence on their photocatalytic activity as a result of quantum size effect. The maximal photocatalytic activity was achieved for x=0.6.
Keywords:
quantum dots; ZnCdS; photocatalysis
Available at various institutes of the ASCR
Photocatalytic activity of ZnxCd.sub.1-x./sub.S quantum dots in dependence on their composition
ZnxCd1-xS quantum dots (QDs) with the different composition x were prepared by precipitation of Zn and Cd acetates with sodium sulphide from aqueous colloid dispersions. Transition energies of these ...
Production of nitrogen vacancy centers in nanocrystalline diamond thin film for quantum biosensing applications
Jakl Krečmarová, Marie; Gulka, Michal; Fekete, Ladislav; Remeš, Zdeněk; Petráková, Vladimíra; Mortet, Vincent; Nesládek, M.
2014 - English
Due to its excellent properties such as chemical stability and biocompatibility, diamond is an ideal material for bio sensing application. In particular, nitrogen vacancy (NV) centres in diamond are promising candidates for optical bio-sensing application in nanodiamond particles and single crystal diamond by irradiation (electron, proton, neutron, particles) followed by annealing has been recently developer. Production of NV centres in CVD diamond thin film is important for fabrication of new bio sensor.
Keywords:
nanocrystalline diamond; nitrogen vacancy centre; nitrogen doping; MW PECVD; photoluminescence
Available at various institutes of the ASCR
Production of nitrogen vacancy centers in nanocrystalline diamond thin film for quantum biosensing applications
Due to its excellent properties such as chemical stability and biocompatibility, diamond is an ideal material for bio sensing application. In particular, nitrogen vacancy (NV) centres in diamond are ...
Silver catalysed nanoscale silicon etching in water vapour
Křížek, Filip; Pikna, Peter; Fejfar, Antonín
2014 - English
N+-doped silicon substrates were etched by water vapour under the silver nanoparticles acting as a catalyst. Thin silver layer was deposited on two silicon wafers, where one of them was thermally annealed in nitrogen to create silver nanoparticles. Subsequently, both samples were annealed in water vapour and afterwards analysed by Scanning Electron Microscope. The images have shown that the annealed silver nanoparticles burrowed into the silicon substrate in the case of both samples. This new method of silicon etching introduces an alternative way of manufacturing nanohole arrays in silicon substrates.\n
Keywords:
silicon etching; water vapour; silver nanoparticles; thermal annealing
Available at various institutes of the ASCR
Silver catalysed nanoscale silicon etching in water vapour
N+-doped silicon substrates were etched by water vapour under the silver nanoparticles acting as a catalyst. Thin silver layer was deposited on two silicon wafers, where one of them was thermally ...
The deposition of amorphous and amorphous hydrogenated silicon with embedded cubic Mg.sub.2./sub.Si nanoparticles
Stuchlíková, The-Ha; Stuchlík, Jiří; Remeš, Zdeněk; Fajgar, Radek; Galkin, N.G.; Galkin, K.N.; Chernev, I.M.
2014 - English
We study possibilities how to increase a by usage of magnesium silicide nanoparticles (Mg2Si-NPs) in structure of Si: H. In this paper we introduce two technics -combination of PECVD and Vacuum Evaporation (VE) and Reactive Laser Ablation (RLA) -for preparation of cubic structure of Mg2Si-NPs in amorphous (a-Si) or amorphous hydrogenated (a-Si: H) silicon matrix. Formation of Mg2Si-NPs was proved by Raman spectroscopy. Likewise we introduce optical changes measured at absorption edge and the first results on realized NIP structures.
Keywords:
Mg.sub.2./sub.Si nanoparticles; a-Si/a-Si:H matrix; RDA; PECVD; RLA
Available at various institutes of the ASCR
The deposition of amorphous and amorphous hydrogenated silicon with embedded cubic Mg.sub.2./sub.Si nanoparticles
We study possibilities how to increase a by usage of magnesium silicide nanoparticles (Mg2Si-NPs) in structure of Si: H. In this paper we introduce two technics -combination of PECVD and Vacuum ...
Influence of dispersed particles on utility properties od polyvinyl alcohol-based nanotextiles: macromechanical properties
Rácová, Z.; Nežerka, V.; Ryparová, Pavla; Kromka, Alexander; Tesárek, Pavel
2014 - English
The paper deals with the influence of different dispersed particles on utility properties of polyvinyl-alcohol (PVA) based nanofiber textiles. The purpose of the dispersed particles was to produce textiles of antibacterial character, and these were added into water-polymer solution, which was used for electrospinning in two various ways: in form of copper and silver ions, or in form of diamond nanoparticles. In order to assess the strength of textiles, macromechanical testing of modified PVA-based nanofiber textiles was carried out on samples with variable weight per area in range between 0.5 and 5 g/m(2). The obtained results were compared with the results of measurements on plain reference samples. The study revealed that the addition of silver ions causes the strength and stiffness reduction, the addition of copper ions has an opposite effect, while the diamond nanoparticles did not have any significant influence on the mechanical properties.\n
Keywords:
macromechanical properties; polymer nanofibers; dispersed particles; stiffness; tensile strength
Available at various institutes of the ASCR
Influence of dispersed particles on utility properties od polyvinyl alcohol-based nanotextiles: macromechanical properties
The paper deals with the influence of different dispersed particles on utility properties of polyvinyl-alcohol (PVA) based nanofiber textiles. The purpose of the dispersed particles was to produce ...
Effect of H- and O-termination of nanocrystalline diamond films on cell adhesion and osteogenic differentiation
Lišková, Jana; Babchenko, Oleg; Varga, Marián; Kromka, Alexander; Hadraba, Daniel; Švindrych, Zdeněk; Bačáková, Lucie
2014 - English
In order to control the hydrophobic or hydrophilic character, the NCD film surfaces were grafted by hydrogen atoms (H-termination) or by oxygen atoms (O-termination). Human mesenchymal stem cells and primary human osteoblasts were used for biological studies on H- and O-terminated NCD films. We found that cells cultivated on O-terminated NCD films exhibit better adhesion than H-terminated NCD films. In addition, the expression of osteogenic cell markers collagen and alkaline phosphatase analysed by Realtime PCR and immunostaining was higher on O-terminated films.
Keywords:
nanocrystalline diamond film; osteoblast; MSC; type I collagen; paxillin
Available at various institutes of the ASCR
Effect of H- and O-termination of nanocrystalline diamond films on cell adhesion and osteogenic differentiation
In order to control the hydrophobic or hydrophilic character, the NCD film surfaces were grafted by hydrogen atoms (H-termination) or by oxygen atoms (O-termination). Human mesenchymal stem cells and ...
The optical spectra of carbon-based thin films measured by the photothermal deflection spectroscopy (PDS)
Remeš, Zdeněk; Pham, T.T.; Varga, Marián; Kromka, Alexander; Stuchlík, Jiří; Mao, H.B.
2014 - English
Our photothermal deflection spectroscopy (PDS) setup allows to measure simultaneously the absolute values of the optical transmittance T, reflectance R and absorptance A spectra of thin layers on glass substrates in the spectral range from ultraviolet to near infrared light with the typical spectral resolution 5 nm in the ultraviolet, 10 nm in visible and 20 nm in the near infrared region. The PDS setup provides the dynamic detection range in the optical absorptance up to 4 orders of magnitude. Here we demonstrate the usability of this setup by comparing the optical absorbance on a series of the carbon layer and nanocrystalline diamond (NCD) thin layers deposited on glass substrates by using the magnetron sputtering and the microwave based surface wave discharge in linear antenna chemical vapor deposition (CVD) processes, respectively. The defect-induced localized states in the energy gap are observed in all carbon layers as well as in NCD.
Keywords:
PDS; thin films; nanodiamond
Available at various institutes of the ASCR
The optical spectra of carbon-based thin films measured by the photothermal deflection spectroscopy (PDS)
Our photothermal deflection spectroscopy (PDS) setup allows to measure simultaneously the absolute values of the optical transmittance T, reflectance R and absorptance A spectra of thin layers on ...
High hazards in laser experimental work: challenges for safety management of laser research facilities
Procházka, Petr; Olšovcová, Veronika; Margarone, Daniele; Přeček, Martin; Korn, Georg
2013 - English
Research developing and exploiting a technology of high power laser systems belongs among the most progressive parts of modern physics. Usage of the laser technology is associated with many kinds of hazards that pose significant risks to both scientific and technical professionals. Therefore, to ensure the personnel safety, the hazards needs to be addressed and thoroughly evaluated to allow not only rigorous design and construction of building and technology but also effective implementation of operational and work procedures. This paper describes the most significant hazards present within the experimental laser facilities.
Keywords:
laser; laser facilities; laser experiments; safety; high hazard management; radiation protection; EMP (high voltage); nanoparticles; oxygen deficiency; cryogenic gases
Available at various institutes of the ASCR
High hazards in laser experimental work: challenges for safety management of laser research facilities
Research developing and exploiting a technology of high power laser systems belongs among the most progressive parts of modern physics. Usage of the laser technology is associated with many kinds of ...
Comparativ study on functionalization of NCD films with amine groups
Artemenko, Anna; Kozak, Halyna; Stuchlík, Jiří; Biederman, H.; Kromka, Alexander
2013 - English
Nanocrystalline diamond (NCD) films are considered as highly attractive material for biosensing due to its unique semiconducting properties. This can be achieved by modification of NCD films surface on molecular level. Typically chemical immobilization of biomoleculs requires the presence of active functional groups on the diamond surface. This was achieved by attachment of -NH2 functional groups on the surface of H- or O-terminated NCD surface via two plasma-based processes. The first process, deposition of thin amine containing polymer by RF magnetron sputtering of Nylon target in Ar/N2 gas mixture. The second process employs RF plasma treatment in NH3 for 10 minutes. Chemical derivatization (CD) XPS analysis revealed that polymeric coating exhibits a higher amount of amino groups than the diamond surface treated in NH3 RF plasma. Results of I-V measurements showed that surface conductivity of H-terminated NCD films was preserved only after the RF sputtering.
Keywords:
diamond; amino functionalization; XPS; surface conductivity
Available at various institutes of the ASCR
Comparativ study on functionalization of NCD films with amine groups
Nanocrystalline diamond (NCD) films are considered as highly attractive material for biosensing due to its unique semiconducting properties. This can be achieved by modification of NCD films surface ...
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