Number of found documents: 623
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ZnO NANOPARTICLES AND THEIR APPLICATIONS – NEW ACHIEVMENTS
Nohavica, Dušan; Gladkov, Petar
2010 - English
The advantages of ZnO are a low price, good gas sensing properties, photocatalytic activity, antibacterial activity, possibility to prepare structures with interesting optical properties, like photonic crystals, catalytic materials etc. In our laboratory the special research type of MOCVD apparatus has been developed. In the study we have investigated the influence of the growth rate on the morphology of ZnO deposited on Si (100), GaP (111) as well as nanoporous GaP. The same apparatus has been used for ZnO nanoparticles preparation with the diameter of individual nanoparticles of about 25 nm. Keywords: ZnO; MOCVD; Applications development ZnO Available at various institutes of the ASCR
ZnO NANOPARTICLES AND THEIR APPLICATIONS – NEW ACHIEVMENTS

The advantages of ZnO are a low price, good gas sensing properties, photocatalytic activity, antibacterial activity, possibility to prepare structures with interesting optical properties, like ...

Nohavica, Dušan; Gladkov, Petar
Ústav fotoniky a elektroniky, 2010

Silica optical microresonators
Jelínek, M.; Todorov, Filip; Matějec, Vlastimil; Chomát, Miroslav; Kubeček, V.; Berková, Daniela
2010 - English
The paper deals with the preparation of spherical silica microresonators by melting silica optical fiber with an oxygen-hydrogen flame. Resonant spectra of prepared spherical silica microresonators suitable for telecommunications and sensors purposes are also presented. Keywords: optical microresonator; communications; sensing; spoje Available at various institutes of the ASCR
Silica optical microresonators

The paper deals with the preparation of spherical silica microresonators by melting silica optical fiber with an oxygen-hydrogen flame. Resonant spectra of prepared spherical silica microresonators ...

Jelínek, M.; Todorov, Filip; Matějec, Vlastimil; Chomát, Miroslav; Kubeček, V.; Berková, Daniela
Ústav fotoniky a elektroniky, 2010

Speech Processing
Vích, Robert
2010 - English
Proceedings of the Workshop on Speech Processing is a periodic publication collecting the contributions presented at the Czech-German Workshop organized every year in September in Prague This proceedings volume includes 22 papers by 41 authors. Papers are devoted to phonetics and prosody, construction of dialogs, speech analysis, synthesis, and recognition and voice conversion. Keywords: spech analysis; speech synthesis; phonetics; syntéza řeči; fonetika Available at various institutes of the ASCR
Speech Processing

Proceedings of the Workshop on Speech Processing is a periodic publication collecting the contributions presented at the Czech-German Workshop organized every year in September in Prague This ...

Vích, Robert
Ústav fotoniky a elektroniky, 2010

METALIC NANOPARTICLES AND NANOSTRUCTURES
Nohavica, Dušan
2010 - English
A brief overview of the field of metallic nanoparticles and nanocrystalline materials preparation and their properties is presented. Dependence of the chemical potential on surface curvature is important for particles solubility in the melt, vapour pressure of liquids as a function of droplet radius, Ostwald ripening and sintering of the individual particles. Melting point and lattice constant depends on the radius of nanoparticles as well. The major processing for nanocrystalline materials production includes chemical reaction, vapour condensation, electrodeposition, ball grinding, SPD etc. Keywords: nanocrystalline material; metallic material Available on request at various institutes of the ASCR
METALIC NANOPARTICLES AND NANOSTRUCTURES

A brief overview of the field of metallic nanoparticles and nanocrystalline materials preparation and their properties is presented. Dependence of the chemical potential on surface curvature is ...

Nohavica, Dušan
Ústav fotoniky a elektroniky, 2010

Electric field generated by higher vibration modes of microtubule
Cifra, Michal; Havelka, D.; Kučera, Ondřej; Pokorný, Jiří
2010 - English
Certain structures in a living cell may generate electric oscillations. Microtubules, which form a part of a cellular skeleton, belong to this class of structures and ful-fill all conditions for generation of electric oscillations in kHz÷GHz band. We present selected results from calculations of the oscillatory electric field generated by higher vibration modes of microtubules. We propose that the electric field of certain modes may play specific function in cellular organization Keywords: Bioelectromagnetism; Microtubules; Polar vibration modes Available at various institutes of the ASCR
Electric field generated by higher vibration modes of microtubule

Certain structures in a living cell may generate electric oscillations. Microtubules, which form a part of a cellular skeleton, belong to this class of structures and ful-fill all conditions for ...

Cifra, Michal; Havelka, D.; Kučera, Ondřej; Pokorný, Jiří
Ústav fotoniky a elektroniky, 2010

Complex Cepstrum in Speech Synthesi
Vondra, Martin; Vích, Robert
2010 - English
In the contribution the use of the complex cepstrum in speech modeling and synthesis is shortly described. The obtained mixed phase parametric speech model is of the finite impulse response type and contains also information about the phase properties of the modeled speech frame. The synthesized speech is more natural, but the memory requirements and numerical complexity are much higher than for minimum phase realization. Keywords: speech analysis; speech synthesis Available in a digital repository NRGL
Complex Cepstrum in Speech Synthesi

In the contribution the use of the complex cepstrum in speech modeling and synthesis is shortly described. The obtained mixed phase parametric speech model is of the finite impulse response type and ...

Vondra, Martin; Vích, Robert
Ústav fotoniky a elektroniky, 2010

STUDY OF ELECTROPHORETIC DEPOSITION OF Pd METAL NANOPARTICLES ON InP AND GaN CRYSTAL SEMICONDUCTORS FOR H2 GAS SENSORS
Žďánský, Karel; Yatskiv, Roman; Grym, Jan; Černohorský, O.; Zavadil, Jiří; Kostka, František
2010 - English
Deposition of Pd nanoparticles (NPs) on InP or GaN single crystal wafer was performed from isooctane colloid solution. Diodes were prepared by making Schottky contact with colloidal graphite on Pd NPs partly coated surface and ohmic contact on the blank side of the wafer. It was found that several ppb of hydrogen in nitrogen gas can be detected by monitoring the change of diode current at a constant bias voltage. Diodes made on GaN were about ten times more sensitive to hydrogen than those made on InP. Keywords: semiconductor devices; nanostructures; sensors Available at various institutes of the ASCR
STUDY OF ELECTROPHORETIC DEPOSITION OF Pd METAL NANOPARTICLES ON InP AND GaN CRYSTAL SEMICONDUCTORS FOR H2 GAS SENSORS

Deposition of Pd nanoparticles (NPs) on InP or GaN single crystal wafer was performed from isooctane colloid solution. Diodes were prepared by making Schottky contact with colloidal graphite on Pd NPs ...

Žďánský, Karel; Yatskiv, Roman; Grym, Jan; Černohorský, O.; Zavadil, Jiří; Kostka, František
Ústav fotoniky a elektroniky, 2010

EPITAXIAL OVERGROWTH OF InP and GaAs MICROPORES, MICROCAVITIES AND MICROLAMELLAS BY InAs AND InGaAs
Nohavica, Dušan; Grym, Jan; Hulicius, Eduard; Pangrác, Jiří; Gladkov, Petar; Jarchovský, Zdeněk
2010 - English
Structural and optical properties of micro and nano-porous InP and GaAs substrates used for an epitaxial overgrowth of thin films were investigated. Both crystalographically oriented (CO) and current line oriented (CLO) pore networks were created by electrochemical dissolution. Heat treatment of InP pores at 650oC and GaAs pores at 750-850oC converted them into microcavities The capability of improved structural quality homo- and hetero-epitaxially overgrown films on the porous InP, was also demonstrated by LPE growth of InP and InAs and GaInAs on GaAs by MOVPE technology. Keywords: A3B5; micropores; heteroepitaxy Available at various institutes of the ASCR
EPITAXIAL OVERGROWTH OF InP and GaAs MICROPORES, MICROCAVITIES AND MICROLAMELLAS BY InAs AND InGaAs

Structural and optical properties of micro and nano-porous InP and GaAs substrates used for an epitaxial overgrowth of thin films were investigated. Both crystalographically oriented (CO) and current ...

Nohavica, Dušan; Grym, Jan; Hulicius, Eduard; Pangrác, Jiří; Gladkov, Petar; Jarchovský, Zdeněk
Ústav fotoniky a elektroniky, 2010

Measurement and Computer Simulation of Electromagnetic Oscillations of Living Cells
Cifra, Michal; Pokorný, Jiří; Vrba, J.
2009 - English
Frohlich postulated coherent polar oscillations as a fundamental biophysical property of biological systems. Recently, Pelling et al. (2004, 2005) detected mechanical vibrations of yeast cell membrane with atomic force microscope (AFM) and analyzed by Fourier analysis in the frequency range 0.5-2 kHz with amplitudes of the order of 1 nm. This article describes the measurement of electric activity of yeast cells in the acoustic frequency range and of mechanical vibrations of cell membrane. Spectrum analyzer and electrically and > electromagnetically screened box with point sensor and amplifiers fed by batteries were used for measurement of synchronized and non synchronized tubulin mutants of yeast cells. We show that the electric activity of synchronized cells in the M phase is greater that of non synchronized cells. That corresponds to the findings of Pohl et al. (1981). Obtained results of measurement of cell electric activity are in good agreement with AFM findings. Keywords: bioelectric phenomena; cellular biophysics; modeling; modelářství Available at various institutes of the ASCR
Measurement and Computer Simulation of Electromagnetic Oscillations of Living Cells

Frohlich postulated coherent polar oscillations as a fundamental biophysical property of biological systems. Recently, Pelling et al. (2004, 2005) detected mechanical vibrations of yeast cell membrane ...

Cifra, Michal; Pokorný, Jiří; Vrba, J.
Ústav fotoniky a elektroniky, 2009

Control system of the laser topographer
Kostka, František; Žďánský, Karel; Zavadil, Jiří; Starý, Robert
2009 - English
Universal apparatus for measuring photoluminescence over surface of semiconductor samples was designed and realized. Keywords: control systems; Laser optic; photolominescence; regulované systémy Available at various institutes of the ASCR
Control system of the laser topographer

Universal apparatus for measuring photoluminescence over surface of semiconductor samples was designed and realized.

Kostka, František; Žďánský, Karel; Zavadil, Jiří; Starý, Robert
Ústav fotoniky a elektroniky, 2009

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