No (412)
Yes (19)
Number of found documents:
431
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Calculations of nanocrystalline diamond-covered waveguides based on amorphous silicon
Jirásek, Vít; Prajzler, Václav; Remeš, Zdeněk
2015 - English
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
Keywords:
nanocrystalline diamond; amorphous silicon; optical waveguides; FEM simulations
Available at various institutes of the ASCR
Calculations of nanocrystalline diamond-covered waveguides based on amorphous silicon
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 ...
Boron-doped diamond electrodes in electroanalysis of reducible organic compounds
Vosáhlová, J.; Zavázalová, J.; Petrák, Václav; Schwarzová-Pecková, K.
2015 - English
Boron doped diamond (BDD) electrodes became a well-established tool in electroanalysis of oxidizable organic compounds, nevertheless their possibilities in electroanalysis of reducible compounds remain relatively unexploited. Thus, in this study the influence of the presence of oxygen, electrode pretreatment, and activation between individual scans for electroreduction of tartrazine and allura red (azo group), 5-nitroquinoline (nitro group and N-heterocycle), vanillin (aromatic aldehyde), and azidothymidine (azide group) using batch voltammetry was tested.
Keywords:
5-nitroquinoline; azo-dyes; boron-doped diamond; boron concentration; voltammetry; reduction
Available at various institutes of the ASCR
Boron-doped diamond electrodes in electroanalysis of reducible organic compounds
Boron doped diamond (BDD) electrodes became a well-established tool in electroanalysis of oxidizable organic compounds, nevertheless their possibilities in electroanalysis of reducible compounds ...
FLC-15: Challenges in polar self-assembling systems
Bubnov, Alexej; Glogarová, Milada
2015 - English
This is the Book of Abstracts for the 15th International Conference on Ferroelectric Liquid Crystals (FLC-15 conference) held in Prague on June 28 - July 3, 2015. The broadening of the field compared to the beginning of this biennial series in 1987 is expressed in the conference subtitle: Challenges in polar self-assembling systems. The continuous worldwide interest to this conference series is proving that it has still a respected position within the series of International/European conferences on liquid crystals covering all interdisciplinary field of the liquid crystal research. At the FLC-15 conference more than 130 participants from 25 countries all over the world will present 5 key-note lectures, 14 invited talks and selected 39 oral contributions. The number has been limited to keep the single session conference format as it is a tradition for the FLC conference series. About 90 posters were presented in two poster sessions. For your convenience, the FLC-15 conference program is presented in this book.
Keywords:
ferroelectric liquid crystals; polar liquid crystalline phases
Available at various institutes of the ASCR
FLC-15: Challenges in polar self-assembling systems
This is the Book of Abstracts for the 15th International Conference on Ferroelectric Liquid Crystals (FLC-15 conference) held in Prague on June 28 - July 3, 2015. The broadening of the field compared ...
Boron-doped diamond electrodes in electroanalysis of reducible organic compounds
Vosáhlová, J.; Zavázalová, J.; Petrák, Václav; Schwarzová-Pecková, K.
2015 - English
Boron doped diamond (BDD) electrodes became a well-established tool in electroanalysis of oxidizable organic compounds; nevertheless their possibilities in electroanalysis of reducible compounds remain relatively unexploited. Thus, in this study the influence of the presence of oxygen, electrode pretreatment, and activation between individual scans for electroreduction of tartrazine and allura red (azo group), 5-nitroquinoline (nitro group and N-heterocycle), vanillin (aromatic aldehyde), and azidothymidine (azide group) using batch voltammetry was tested.
Keywords:
5-nitroquinoline; azo-dyes; boron-doped diamond; boron concentration; voltammetry; reduction
Available at various institutes of the ASCR
Boron-doped diamond electrodes in electroanalysis of reducible organic compounds
Boron doped diamond (BDD) electrodes became a well-established tool in electroanalysis of oxidizable organic compounds; nevertheless their possibilities in electroanalysis of reducible compounds ...
Interpretation of the C=O band of modified diamond nanoparticles by means of DFT theory
Jirásek, Vít; Kozak, Halyna; Remeš, Zdeněk; Kromka, Alexander
2015 - English
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.
Keywords:
diamond nanoparticles; functionalized diamond surface; density functional theory; vibrational spectra; FTIR
Available at various institutes of the ASCR
Interpretation of the C=O band of modified diamond nanoparticles by means of DFT theory
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 ...
Verification of the use of pva based nanofiber textiles as a rehabilitation for the structures attack by wood decaying fungi
Rácová, Z.; Ryparová, Pavla; Wasserbauer, R.; Nežerka, V.; Tesárek, Pavel; Demo, Pavel
2014 - English
The presented paper is focused on the investigation of antifungal properties of nanofiber PVA-based textiles with incorporated copper and silver ions. In particular, the ability to prevent the growth of Dry rot fungus (Serpula lacrymans) was studied in laboratory conditions. For that purpose, the Petri dishes with malt agar were inoculated with square cut-outs of seed stocks, consequently covered by the nanofiber textiles and kept in an incubator at 28 degrees C. The fungal growth had been monitored and recorded at regular intervals for 28 days. The comparison of the individual treatments (PVA, PVA + Ag, PVA + Cu, PVA + Ag + Cu) is finally discussed.\n
Keywords:
nanofiber textiles; dry rot fungus; PVA; metal ions
Available at various institutes of the ASCR
Verification of the use of pva based nanofiber textiles as a rehabilitation for the structures attack by wood decaying fungi
The presented paper is focused on the investigation of antifungal properties of nanofiber PVA-based textiles with incorporated copper and silver ions. In particular, the ability to prevent the growth ...
Development of materials science in research and education. Book of abstracts of the 24th joint seminar
Kožíšek, Zdeněk; Nitsch, Karel
2014 - English
Topics: - Trends in development of materials research - Education of materials science at the universities - Information about the research programmes of individual institutions - Information on equipment for preparation and characterisation of materials - Results of materials science research
Keywords:
material sciences
Available at various institutes of the ASCR
Development of materials science in research and education. Book of abstracts of the 24th joint seminar
Topics: - Trends in development of materials research - Education of materials science at the universities - Information about the research programmes of individual institutions - Information on ...
Highly luminescent nanophosphors - new physics, technologies and applications
Nikl, Martin; Čuba, V.; Bárta, J.; Jarý, Vítězslav
2014 - English
The application of radiation synthesis in the manufacturing nanopowders of binary and ternary oxide nanophosphors is reviewed. Technological routes are described: irradiation of specific solutions containing soluble metal salts and OH radical scavenger by UV or ionizing radiation results in the formation of finely dispersed solid phase which is separated from the solution and subsequently converted by further thermal treatment into crystalline nanopowders with typical dimension of grains of several tens of nanometers. Doped ZnO, Y2O3, Y3Al5O12, Lu3Al5O12 and Gd3(Ga,Al)5O12 nanophosphors were prepared and their luminescence and scintillation characteristics were measured. In the photoluminescence decay of doped garnets the distinct effect of nanosized grains was found consisting in the slowing-down of the decay due to the change of effective refractive index.
Keywords:
scintillator; phosphor; radiation method; nanocrystals; garnet; ZnO; Y.sub.2./sub.O.sub.3./sub.; rare earth dopants
Available at various institutes of the ASCR
Highly luminescent nanophosphors - new physics, technologies and applications
The application of radiation synthesis in the manufacturing nanopowders of binary and ternary oxide nanophosphors is reviewed. Technological routes are described: irradiation of specific solutions ...
Electronic excitation energy transfer between quasi-zero-dimensional systems
Král, Karel; Menšík, Miroslav
2014 - English
Electronic excitation energy transfer is studied theoretically within a prototype system of quantum dots using the excitonic representation of the electronic states of two quasi-zero dimensional subsystems, between which the excitation energy is transferred in a process treated as an irreversible kinetic phenomenon. The electron-phonon interaction is used to circumvent the energy conservation problem, especially when considering the uphill and downhill excitation transfer processes. The theory is studied upon utilizing a simplified model of two interacting quantum dots, both coupled to their environment. The theoretical approach is documented by numerical calculations. The results could be relevant to various cases of the electronic excitation energy transfer between quasi zero dimensional nanostructures.
Keywords:
quantum dots; energy transfer; electron-phonon interaction
Available at various institutes of the ASCR
Electronic excitation energy transfer between quasi-zero-dimensional systems
Electronic excitation energy transfer is studied theoretically within a prototype system of quantum dots using the excitonic representation of the electronic states of two quasi-zero dimensional ...
Algicidal properties nanofibrous fabrics doped by metals
Ryparová, Pavla; Wasserbauer, R.; Rácová, Z.; Demo, Pavel; Tesárek, Pavel
2014 - English
The paper presents a novel protection against algae by nanofiber fabrics doped with metal ions. Nanofiber textiles were prepared by electrospinning on the Nanospider LB 500 device, equipped with cylindrical electrodes of a length 600 mm and electrode distance about 140 mm. The produced nanofiber textiles had a specific weight between 2 and 4 g/m2. The entire surface was covered with algae commonly accompanied by bacteria. The sample had placed in the middle of circular dishes having the diameter 20 mm. The cultivation took place at light environment in common laboratory conditions. Algicidal effect was evaluated as the resulting halo size and quality around the sample. The PVA treated sample had not produce any halo effect, unlike the samples with the addition of metal salts (AgNO3, CuSO4 center dot 5H(2)O) that exhibited the halo effect dependent on the concentration the salts, usually ranging from 0.3-2 mm, giving the evidence about their algicidal properties.\n
Keywords:
algicidal properties; polymer nanofibers; dispersed nanoparticles; metal nanoparticles; stone
Available at various institutes of the ASCR
Algicidal properties nanofibrous fabrics doped by metals
The paper presents a novel protection against algae by nanofiber fabrics doped with metal ions. Nanofiber textiles were prepared by electrospinning on the Nanospider LB 500 device, equipped with ...
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