Number of found documents: 419
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Study of mechanical properites of nanostructured polymer coatings prepared using plasma enhanced chemical vapor deposition
Buršíková, V.; Homola, V.; Peřina, Vratislav
2015 - English
The aim of the present work was to deposit transparent polymer SiOxCyHz protective coatings from hexamethyldisiloxane/ oxygen mixtures in capacitively coupled glow discharge. The coatings prepared under dusty plasma conditions showed nanocomposite character. Complex characterization of the local mechanical properties was carried out on the prepared samples from nano to microscale using indentation techniques. The coatings were very elastic, they exhibited high elastic recovery and low plastic deformation even at indentation depths approaching the coating thickness. Keywords: PECVD; hexamethyldisiloxane; mechanical properties Available at various institutes of the ASCR
Study of mechanical properites of nanostructured polymer coatings prepared using plasma enhanced chemical vapor deposition

The aim of the present work was to deposit transparent polymer SiOxCyHz protective coatings from hexamethyldisiloxane/ oxygen mixtures in capacitively coupled glow discharge. The coatings prepared ...

Buršíková, V.; Homola, V.; Peřina, Vratislav
Ústav jaderné fyziky, 2015

IMPEDANCE MEASUREMENT OF GAS SENSORS WITH NICKEL(II)-AND COPPER(II)-OXIDE ACTIVE LAYERS
Horák, Pavel; Khun, J.; Vrňata, M.; Bejšovec, Václav; Lavrentiev, Vasyl; Vacík, Jiří
2015 - English
Thin layers (90 nm) of nickel(II)- and copper(II)- oxide were deposited onto ceramic sensor substrates equipped with interdigital electrodes for signal reading. The deposition was carried out in two or three steps: (i) sputtering by means of Ar ion beam from pure (99.99%) metal targets, (ii) following thermal oxidation (400 degrees C for 5 h) in air, (iii) in some cases - sputtering of Pd catalyst to the surface. Then the impedance response of produced sensors (NiO, NiO+Pd, CuO, CuO+Pd) to 1000 ppm of hydrogen and 1000 ppm of methanol vapor was measured. Impedance measurements were performed in the frequency range from 40 Hz to 100 MHz. The obtained data were depicted in Nyquist representation (i.e. imaginary vs. real part of complex impedance). These diagrams have a character of one complete and one incomplete semicircle, each of them corresponding to a parallel RC-element. It was proved, that both NiO and CuO behave like p-type semiconductors; the sensor impedance increases on exposure to reducing gases. The best sensitivity was achieved on NiO+Pd sensor - during detection of hydrogen (1000 ppm) the real part of complex impedance measured at 40 Hz increased from 120 to 350 Omega. Keywords: gas sensors; impedance measurement; nickel(II) oxide and copper(II) oxide Available at various institutes of the ASCR
IMPEDANCE MEASUREMENT OF GAS SENSORS WITH NICKEL(II)-AND COPPER(II)-OXIDE ACTIVE LAYERS

Thin layers (90 nm) of nickel(II)- and copper(II)- oxide were deposited onto ceramic sensor substrates equipped with interdigital electrodes for signal reading. The deposition was carried out in two ...

Horák, Pavel; Khun, J.; Vrňata, M.; Bejšovec, Václav; Lavrentiev, Vasyl; Vacík, Jiří
Ústav jaderné fyziky, 2015

RESPONSE OF SURFACE MORPHOLOGY IN COBALT-FULLERENE MIXTURE FILMS UPON VARIATION OF THE METAL CONTENT
Lavrentiev, Vasyl; Lavrentieva, Inna; Vacík, Jiří
2015 - English
The morphology and roughness of the films show great change around some critical composition x(c) of the mixture film (x(c) approximate to 3). The films with lower Co content (x < 3) is rather smooth and the roughness is rather low. However, if x >= 3, the roughness of the CoxC60 films dramatically increases and sharp protrusions appear on the surface that reflects an important phase transformation in the film structure. The obtained AFM results define the concentration interval of the Co solubility in solid C-60 (x < 3), which was found to be narrower than that evaluated from spectroscopic experiments (see the text). This interval suggests a formation of the Co1C60 and Co2C60 fullerides in the CoxC60 mixtures where the Co atoms occupy the tetrahedral holes in the fullerene lattice. The dramatic change of the surface morphology at x >= 3 reflects the pronounced Co clustering which likely occurs due to numerical filling the octahedral pores. Formation of the protrusions on the surface of the supersaturated CoxC60 mixture films (x > 3) is a consequence of the compressive stress arising in the film due to the Co clustering. Keywords: Fullerene; Cobalt; mixture; roughness; surface; phase transformation Available at various institutes of the ASCR
RESPONSE OF SURFACE MORPHOLOGY IN COBALT-FULLERENE MIXTURE FILMS UPON VARIATION OF THE METAL CONTENT

The morphology and roughness of the films show great change around some critical composition x(c) of the mixture film (x(c) approximate to 3). The films with lower Co content (x ...

Lavrentiev, Vasyl; Lavrentieva, Inna; Vacík, Jiří
Ústav jaderné fyziky, 2015

Residual Stress Distribution Measurement by Neutron Diffraction of the Single Pass Fillet Steel Welds
Mráz, Ľ.; Karlsson, L.; Vrána, Miroslav; Mikula, Pavol
2014 - English
In this contribution the results of residual strain/stress measurements performed on several single pass fillet steel welds which were carried out at different welding conditions, namely, with different filler materials are presented. Keywords: residual stress; neutron diffraction; steel welds; fonetika; oceli Available at various institutes of the ASCR
Residual Stress Distribution Measurement by Neutron Diffraction of the Single Pass Fillet Steel Welds

In this contribution the results of residual strain/stress measurements performed on several single pass fillet steel welds which were carried out at different welding conditions, namely, with ...

Mráz, Ľ.; Karlsson, L.; Vrána, Miroslav; Mikula, Pavol
Ústav jaderné fyziky, 2014

Determination of reference values of element contents in certified reference material SWCNT-1 by INAA a PGAA
Kučera, Jan; Sturgeon, R. E.; Grinberg, P.; Oflaz, R.; Paul, R. L.; Bennett, J. W.; De Nadai Fernandes, E. A.; Kubešová, Marie; Bacchi, M. A.; Stopic, A. J.
2014 - Czech
Instrumental neutron activation analysis with both relative and k-0 standardization was used in four experienced laboratories to determine element mass fractions in single-wall carbon nanotube certified reference material (CRM) SWCNT-1. Results obtained were evaluated using the NIST “Type B On Bias” approach and yielded consensus values in agreement with NRCC certified values for Fe, Co, Ni and Mo and provided mass fraction values for thirteen additional elements, namely Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Br, La, W and Au. In addition, prompt gamma neutron activation analysis was employed to determine mass fractions of H, B, Co, Ni, and Mo. Results of this work provide a basis for the establishment of reference values of element mass fractions in CRM SWCNT-1, thus expanding its usability for more accurate characterization and benchmarking of similar nanotechnology materials. Keywords: carbon nanotubes; neutron activation analysis Available at various institutes of the ASCR
Determination of reference values of element contents in certified reference material SWCNT-1 by INAA a PGAA

Instrumental neutron activation analysis with both relative and k-0 standardization was used in four experienced laboratories to determine element mass fractions in single-wall carbon nanotube ...

Kučera, Jan; Sturgeon, R. E.; Grinberg, P.; Oflaz, R.; Paul, R. L.; Bennett, J. W.; De Nadai Fernandes, E. A.; Kubešová, Marie; Bacchi, M. A.; Stopic, A. J.
Ústav jaderné fyziky, 2014

A comparative study of the total mercury determination in highly contaminated soils by AAS and RNAA methods
Sysalová, J.; Kučera, Jan; Zvěřina, O.
2014 - English
Výsledky srovnávací studie stanovení celkové rtuti ve vysoce kontaminovaných půdách do obsahu 25 mg/kg byly získány dvěma nezávislými metodami: metodou AAS s použitím jednoúčelového spektrometru AMA-254 s přímým dávkováním 10-25 mg pevných vzorků a metodou neutronové aktivační analýzy s radiochemickou separací (RNAA) s navážkami 150 mg vzorků. Vzorky půd byly upravovány sítováním a kryogenním mletím. Kontrola kvality výsledků byla provedena analýzami certifikovaných referenčních materiálů NIST SRM 2711 Montana Soil a NIST SRM 2711a Montana Soil II. Pro vyšší obsahy rtuti nad 25 mg/kg, byly vzorky ředěny mořským pískem v poměru 1:10 a homogenizovány před dávkováním do AMA-254. Proces ředění vzorků v pevném stavu byl ověřen analýzou říčního sedimentu ERM-CC580. Výsledky analýz celkových obsahů rtuti v kontaminovaných půdách získané nezávislými metodami AAS a RNAA vykazují velmi dobrou shodu pro oba uvedené postupy. Keywords: mercury; RNAA; Advanced Mercury Analyser Available at various institutes of the ASCR
A comparative study of the total mercury determination in highly contaminated soils by AAS and RNAA methods

Výsledky srovnávací studie stanovení celkové rtuti ve vysoce kontaminovaných půdách do obsahu 25 mg/kg byly získány dvěma nezávislými metodami: metodou AAS s použitím jednoúčelového spektrometru ...

Sysalová, J.; Kučera, Jan; Zvěřina, O.
Ústav jaderné fyziky, 2014

Zpráva o kalibraci přístroje TriCarb 3180 pro měření karbonátových forem 14C v exponovaných roztocích sorbentu
Světlík, Ivo; Tomášková, Lenka; Megisová, Natália; Wágnerová, Markéta; Ryska, František
2013 - Czech
Keywords: LSC; radiocarbon; releases from nuclear power plants; stack air Available at various institutes of the ASCR
Zpráva o kalibraci přístroje TriCarb 3180 pro měření karbonátových forem 14C v exponovaných roztocích sorbentu

Světlík, Ivo; Tomášková, Lenka; Megisová, Natália; Wágnerová, Markéta; Ryska, František
Ústav jaderné fyziky, 2013

NANOSTRUCTURE CHARACTERIZATION OF IN738LC SUPERALLOY FATIGUED AT HIGH TEMPERATURE
Petrenec, M.; Strunz, Pavel; Gasser, U.; Heczko, Milan; Zálešák, J.; Polák, Jaroslav
2013 - English
The nanostructure of Inconel 738LC Ni-superalloy strengthened by trimodal Y precipitates distribution was investigated after Low Cycle Fatigue (LFC) loading at temperature 700°C. Different microscopic techniques as Scanning Electron Microscope (SEM) equipped with STEM detectro, transmission Kikuchi diffraction in the SEM, transmission electron microscope (TEM) in the bright field mode and high resolution transmission electron mciroscopes (HRTEM) in STEM mode were used for the characterization and quantification of superalloy nanostructure. The characteristic morphology of y precipitates was examined by ex-situ and in-situ Small Angle Neutron Scattering (SANS) at high temperatures. All adopted microscopic techniques indicate that the morphology of y precipitates distributed in the y matrix as recived state corresponds to two types, i.e. large cuboid-like precipitates with the size around 670 nm, and the spherical precipitates with the diameter 52nm. After eh LCF tests at temperature 700°C, the ex-situ SANS measurement yielded addititonal scattering intensities coming from another small y precipitetes with estimated size up to 10nm. Keywords: superalloys; nano-precipitation; neutron scattering; STEM detector; TEM Fulltext is available at external website.
NANOSTRUCTURE CHARACTERIZATION OF IN738LC SUPERALLOY FATIGUED AT HIGH TEMPERATURE

The nanostructure of Inconel 738LC Ni-superalloy strengthened by trimodal Y precipitates distribution was investigated after Low Cycle Fatigue (LFC) loading at temperature 700°C. Different microscopic ...

Petrenec, M.; Strunz, Pavel; Gasser, U.; Heczko, Milan; Zálešák, J.; Polák, Jaroslav
Ústav jaderné fyziky, 2013

Nedestruktivní stanovení dusíku v biologických a jiných materiálech fotonovou aktivační analýzou
Krausová, Ivana; Mizera, Jiří; Chvátil, David; Krist, Pavel; Řanda, Zdeněk; Kučera, Jan; Štursa, Jan
2013 - Czech
Byl vyvinut postup instrumentální gama aktivační analýzy (IGAA) pro stanovení dusíku v biologických materiálech. Stanovení je založeno na měření nespecifického anihilačního záření gama o energii 511 keV emitovaného 13N, který je produktem fotojaderné reakce 14N(γ, n)13N a je čistým pozitronovým zářičem. Metoda IGAA umožnila stanovení dusíku pod úrovní 1 hmotnostního procenta ve vybraných biolgických referenčních materiálech - NIST RM 8433 Corn Bran, 1547 Peach Leaves, 8414 Bovine Muscle, and 1577b Bovine Liver. Optimalizovaný postup byl také použit pro stanovení dusíku v práškových nanodiamantech pro lékařské účely. A procedure has been developed for assaying nitrogen in biological materials by means of instrumental photon activation analysis (IPAA). The determination has been based on counting of the non-specific 511 keV annihilation gamma rays of 13N, product of the photonuclear reaction 14N(γ, n)13N and a pure positron emitter. IPAA allowed determination of nitrogen down to 1 wt.%. in selected biological reference standards - NIST RM 8433 Corn Bran, 1547 Peach Leaves, 8414 Bovine Muscle, and 1577b Bovine Liver. The optimized procedure was applied also to assaying nitrogen in pulverized nanodiamond intended for medical purposes. Keywords: instumental photon activation analysis; nitrogen; biological materials; nanodiamond; dusík; materiály Available at various institutes of the ASCR
Nedestruktivní stanovení dusíku v biologických a jiných materiálech fotonovou aktivační analýzou

Byl vyvinut postup instrumentální gama aktivační analýzy (IGAA) pro stanovení dusíku v biologických materiálech. Stanovení je založeno na měření nespecifického anihilačního záření gama o energii 511 ...

Krausová, Ivana; Mizera, Jiří; Chvátil, David; Krist, Pavel; Řanda, Zdeněk; Kučera, Jan; Štursa, Jan
Ústav jaderné fyziky, 2013

K otázce lokalizace mateřského kráteru australoasijských tektitů: Geochemické, izotopové, geografické a balistické faktory
Mizera, Jiří; Řanda, Zdeněk
2013 - Czech
Soubor australoasijských tektitů (AAT) byl geochemicky charakterizován metodami aktivační analýzy. Na základě získaných výsledků a dříve publikovaných geochemických, mineralogických, petrografických a izotopových dat pro AAT a jejich potencionální zdrojové materiály, spolu s uvážením geografických a balistických omezení známých pro jiné tektity a jejich pádová pole, jsou diskutovány pravděpodobné zdrojové materiály a lokalizace mateřského impaktového kráteru pro AAT. A set of Australasian tektites (AAT) has been geochemically characterized by methods of activation analysis. Based on the acquired data as well as previously published geochemical, mineralogical, petrographical and isotopic data on both AAT and their potential source materials, and considering geographic and ballistic constraints known from other tektites and their strewn fields, probable source materials and location of the parent impact crater for AAT have been discussed. Keywords: Australasian tektites; impact; parent crater; activation analysis; teorie dat; analýza Available at various institutes of the ASCR
K otázce lokalizace mateřského kráteru australoasijských tektitů: Geochemické, izotopové, geografické a balistické faktory

Soubor australoasijských tektitů (AAT) byl geochemicky charakterizován metodami aktivační analýzy. Na základě získaných výsledků a dříve publikovaných geochemických, mineralogických, petrografických a ...

Mizera, Jiří; Řanda, Zdeněk
Ústav jaderné fyziky, 2013

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