No (253)
Yes (4)
Number of found documents:
257
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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 ...
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
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 ...
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. High total mercury (T-Hg) contents in soils, up to 25 mg kg−1, were determined by two independent methods: a one-purpose atomic absorption spectrometer AMA-254 (Advanced Mercury Analyser) with direct solid sampling, and radiochemical neutron activation analysis (RNAA), using sample masses of 10 mg to 25 mg and about 150 mg, respectively. An excellent agreement between results of both methods was obtained. For quality control (QC) purposes, NIST SRM 2711 Montana Soil and NIST SRM 2711a were analysed by both methods using the above sample masses. The results obtained were compared with the NIST certified values within the uncertainty margins, thus proving the accuracy of the procedures employed. It has been found that the cryogenic grinding used provided sufficiently representative and homogeneous samples. A test in which HgS was analysed by RNAA showed that even mercury present in sulfide form would be fully recovered using the procedures employed. For contents of T-Hg above the upper limit of the AMA-254 working range (500 ng), samples were firstly diluted with sea sand in the ratio 1:10 and homogenised well to get RSD below 5%. The dilution procedure was verified using the certified reference material ERM-CC580 Estuarine Sediment.
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 ...
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 ...
Features of Nuclear Reactions with Light Weakly Bond Nuclei at Energy near the Coulomb Barrier
Skobelev, N. K.; Penionzhkevich, Y. E.; Kroha, Václav; Burjan, Václav; Hons, Zdeněk; Mrázek, Jaromír; Piskoř, Štěpán; Šimečková, Eva; Voskoboynik, E. I.
2012 - English
In the experiments carried out by ion beam He-6 of the cyclotron complex DRIBs (JINR) and He-3 beam cyclotron U-120M of the NPI, Czech Academy of Sciences have been investigated reaction Sc-45+He-3, He-6 and Au-197+He-3, He-6 in the energy range near the Coulomb barrier. It were obtained the experimental values of the cross sections for complete fusion reactions and direct reactions for formation of the isotopes Sc-43, Sc-44 and Sc-46 also Au-196 and Au-198 as a function of the bombarding He-3 and He-6 energy. Despite the low binding energy of He-3 and the positive Q-values leading to the formation of isotopes Sc-44 and Sc-46 also Au-196 and Au-198, the behavior of the excitation functions with the formation of these isotopes is different from the excitation functions for d, He-6.
Keywords:
He-6; cyclotron U-120M; cross section
Available at various institutes of the ASCR
Features of Nuclear Reactions with Light Weakly Bond Nuclei at Energy near the Coulomb Barrier
In the experiments carried out by ion beam He-6 of the cyclotron complex DRIBs (JINR) and He-3 beam cyclotron U-120M of the NPI, Czech Academy of Sciences have been investigated reaction Sc-45+He-3, ...
Experimental Determination of Neutron Room Background at the NPI Cyclotron U-120M
Štefánik, M.; Bém, Pavel; Honusek, Milan; Katovsky, K.; Majerle, Mitja; Novák, Jan; Šimečková, Eva
2012 - English
During the operation of external neutron generators of the Nuclear Physics Institute of The Academy of Sciences of the Czech Republic, the neutron room background is produced in cyclotron hall. To assess this effect, the neutron room background was measured using the activation method of dosimetry foils. To unfold the background spectrum from the set of measured reaction rates, the method of spectrum description by the special analytical function was employed.
Keywords:
activation detector; external neutron generator; gamma-ray spectroscopy; isochronous Cyclotron U-120M; neutron room background; neutron spectrum reconstruction; reaction rate; white neutron spectrum
Available at various institutes of the ASCR
Experimental Determination of Neutron Room Background at the NPI Cyclotron U-120M
During the operation of external neutron generators of the Nuclear Physics Institute of The Academy of Sciences of the Czech Republic, the neutron room background is produced in cyclotron hall. To ...
Nondestructive Neutron Diffraction Residual Stress Measurements in a Large Depth in Steels
Woo, W.; Em, V.; Mikula, Pavol; Šaroun, Jan; Seong, B. S.
2012 - English
Residual stresses can be effectively and nondestructively measured through a large thickness of e.g. welded plates, by means of a new design of a reactor-based neutron diffractometer. Most of the engineering neutron diffractometers have a difficulty in increasing neutron penetration capability over 25 mm total thickness in steels. However, it can be significantly enhanced up to 70 mm with 4-mm spatial resolution along the depth by using the wavelength selection in combination with neutron focusing by cylindrically bent perfect monochromator. Present paper presents details of neutron diffractometer performance and some results.
Keywords:
stress; analysis; neutron diffraction
Available at various institutes of the ASCR
Nondestructive Neutron Diffraction Residual Stress Measurements in a Large Depth in Steels
Residual stresses can be effectively and nondestructively measured through a large thickness of e.g. welded plates, by means of a new design of a reactor-based neutron diffractometer. Most of the ...
A new set-up for total reaction cross section measuring
Sobolev, Yuri, G.; Ivanov, M. P.; Kugler, Andrej; Penionzhkevich, Y. E.
2012 - English
The experimental method and set-up based on 4 P n-gamma-technique for direct and model-independent measuring of the total reaction cross section sigma(R) have been presented. The excitation function sigma(R)(E) for He-6+Au-197 reaction at the Coulomb barrier energy region has been measured. The measured data are compared with the summarized cross section which has been prepared by summing of measured cross sections of main reaction channels: 1n-transfer and Au-197(He-6, xn)Tl203-xn with x = 2 divided by 7 evaporation reaction channels.\n\n
Keywords:
cross section; reaction; measurement
Available at various institutes of the ASCR
A new set-up for total reaction cross section measuring
The experimental method and set-up based on 4 P n-gamma-technique for direct and model-independent measuring of the total reaction cross section sigma(R) have been presented. The excitation function ...
Urban Structure Analysis
Vašata, D.; Exner, Pavel; Šeba, Petr
2011 - English
The built-up land represents an important type of overall landscape. We analyse the structure of built-up land in largest cities in the Czech Republic and selected cities in the USA using the framework of statistical physics. To do this, both the variance of the built-up area and the number variance of built-up landed plots in circles are calculated. In both cases the variance as a function of a circle radius follows a power law. The obtained value of the exponents are comparable to exponents typical for critical systems. The study is based on cadastral data in the Czech Republic and building footprints GIS data in the USA.
Keywords:
Urban structure; critical systems; self-organized criticality
Available at various institutes of the ASCR
Urban Structure Analysis
The built-up land represents an important type of overall landscape. We analyse the structure of built-up land in largest cities in the Czech Republic and selected cities in the USA using the ...
Detectability of changes in cosmic-ray counting rate measured with the Liulin detector
Malušek, Alexandr; Kubančák, Ján; Ambrožová, Iva
2011 - English
Keywords:
cosmic-ray; Liulin detector; solar energetic particles
Available at various institutes of the ASCR
Detectability of changes in cosmic-ray counting rate measured with the Liulin detector
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