Number of found documents: 198
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Calibration and Exact Characterization of Aerosol Deposit colected by SDI Impactor
Havránek, Vladimír
2016 - English
Ion beam analytical methods as PIXE (Particle induced X-ray emission), PIGE (Particle induced gamma-ray emission) and RBS (Rutherford backscattering spectrometry) are frequently used for elemental analysis of different types of atmospheric aerosol samples in a form of aerosol deposits on thin plastic filters or foils (Alfassi and Peisach, 1991, Johansson and Campbell, 1988). An ideal sample for analysis is thin homogeneous aerosol deposit with known deposit area. However in practice such samples are rare. They are often thick (more than limit for thin target approximation i.e. larger then few hundred micrograms per square centimetres), of irregular shape and unknown deposit area. In such conditions all obtained elemental mass results should be corrected for apparent deposit thickness, deposit homogeneity and effective deposit area. Keywords: atmospheric aerosols; PIXE; RBS; calibration; elemental concentration Available at various institutes of the ASCR
Calibration and Exact Characterization of Aerosol Deposit colected by SDI Impactor

Ion beam analytical methods as PIXE (Particle induced X-ray emission), PIGE (Particle induced gamma-ray emission) and RBS (Rutherford backscattering spectrometry) are frequently used for elemental ...

Havránek, Vladimír
Ústav jaderné fyziky, 2016

Study of fully automated analyzing system for the study of low-dose radiation effects on cellular radiobiology
Nagasaki, Y.; Matuo, Y.; Pachnerová Brabcová, Kateřina; Yasuda, N.
2016 - English
Study of fully automated analyzing system for the study of low-dose radiation effects on cellular radiobiology (poster) Keywords: storage facility; dosimetry; irradiation Available at various institutes of the ASCR
Study of fully automated analyzing system for the study of low-dose radiation effects on cellular radiobiology

Study of fully automated analyzing system for the study of low-dose radiation effects on cellular radiobiology (poster)

Nagasaki, Y.; Matuo, Y.; Pachnerová Brabcová, Kateřina; Yasuda, N.
Ústav jaderné fyziky, 2016

PHASE EVOLUTION IN Ni-48 at.% TI SHAPE MEMORY ALLOY PREPARED BY SELF-PROPAGATING HIGH-TEMPERATURE SYNTHESIS
Karlík, M.; Haušild, P.; Beran, Přemysl; Novák, P.; Čapek, J.; Kučera, V.; Kopeček, Jaromír
2015 - English
In Ni rich Ni–Ti alloys, various phases such as hexagonal Ni3Ti, cubic NiTi2 and rhombohedral Ni4Ti3 appear during heat treatment. The presence of these precipitates affects the shape memory effect and superelasticity in an important manner. In this paper we present a study of the phase evolution during annealing of the Ni–48at.%Ti shape memory alloy elaborated by self-propagating high-temperature synthesis (SHS). Morphology and crystallography of the phases were examined by means of light metallography, scanning electron microscopy (SEM), neutron and X-ray diffraction, transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). Besides the phases mentioned in the\nliterature, a Ni-rich phase with the composition near Ni3Ti2 stoichiometry and having a cubic symmetry was found. This phase develops from Ni4Ti3 particles during slow (furnace) cooling from the temperature of 1000 °C. Its particles have the form of thin platelets coherent with the (B2) NiTi matrix. The orientation relation is either cube-to-cube, [111]P || [115]B2 and (1-10)P || (1-10)B2 or [011]P || [011]B2 and (1-10)P || (1-41)B2.\n Keywords: NiTi shape memory alloy; neutron diffraction; phase analysis; light and electron microscopy Available at various institutes of the ASCR
PHASE EVOLUTION IN Ni-48 at.% TI SHAPE MEMORY ALLOY PREPARED BY SELF-PROPAGATING HIGH-TEMPERATURE SYNTHESIS

In Ni rich Ni–Ti alloys, various phases such as hexagonal Ni3Ti, cubic NiTi2 and rhombohedral Ni4Ti3 appear during heat treatment. The presence of these precipitates affects the shape memory effect ...

Karlík, M.; Haušild, P.; Beran, Přemysl; Novák, P.; Čapek, J.; Kučera, V.; Kopeček, Jaromír
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

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

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

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 ...

Štefánik, M.; Bém, Pavel; Honusek, Milan; Katovsky, K.; Majerle, Mitja; Novák, Jan; Šimečková, Eva
Ústav jaderné fyziky, 2012

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 ...

Woo, W.; Em, V.; Mikula, Pavol; Šaroun, Jan; Seong, B. S.
Ústav jaderné fyziky, 2012

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