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Vliv kryogenního mletí na homogenitu jódu v NIST SRM1548a Typical Diet
Kameník, Jan; Kučera, Jan
2016 - český
The reference material NIST SRM 1548a Typical Diet has a certified iodine mass fraction of 0.759±0.103 mg kg-1. The expanded uncertainty is rather large (relative value 13.6 %), thus the material does not provide strict requirements for quality control results. Milling of NIST SRM 1548a at the temperature of liquid nitrogen yielded free-flowing material. Iodine mass fraction in the original and cryo-ground materials was determined by epithermal neutron activation analysis (ENAA) and radiochemical neutron activation analysis (RNAA). The average and standard deviation from both methods was 0.73±0.03 mg kg-1 (20 values). The determined mass fraction was in a close agreement with the certified value of NIST SRM 1548a, thus iodine total content was not influenced by the milling procedure. In comparison to iodine mass fraction determined in the original NIST SRM 1548a 0.72±0.07 mg kg-1 (average ± standard deviation, 14 values), the standard deviation for cryo-ground material was considerably lower. The prepared quality control material sets up more stringent requirements on the validation and quality control procedures of the measurement of iodine mass fraction in such a composite food matrices. We believe that the iodine random inhomogeneity in the original NIST SRM 1548a is due to insufficient mixing of some iodine-rich component in the complex food matrices. Milling at the temperature of liquid nitrogen offers an effective option for production of future reference materials of this kind. The reference material NIST SRM 1548a Typical Diet has a certified iodine mass fraction of 0.759±0.103 mg kg-1. The expanded uncertainty is rather large (relative value 13.6 %), thus the material does not provide strict requirements for quality control results. Milling of NIST SRM 1548a at the temperature of liquid nitrogen yielded free-flowing material. Iodine mass fraction in the original and cryo-ground materials was determined by epithermal neutron activation analysis (ENAA) and radiochemical neutron activation analysis (RNAA). The average and standard deviation from both methods was 0.73±0.03 mg kg-1 (20 values). The determined mass fraction was in a close agreement with the certified value of NIST SRM 1548a, thus iodine total content was not influenced by the milling procedure. In comparison to iodine mass fraction determined in the original NIST SRM 1548a 0.72±0.07 mg kg-1 (average ± standard deviation, 14 values), the standard deviation for cryo-ground material was considerably lower. The prepared quality control material sets up more stringent requirements on the validation and quality control procedures of the measurement of iodine mass fraction in such a composite food matrices. We believe that the iodine random inhomogeneity in the original NIST SRM 1548a is due to insufficient mixing of some iodine-rich component in the complex food matrices. Milling at the temperature of liquid nitrogen offers an effective option for production of future reference materials of this kind. Klíčová slova: SRM1548a Typical Diet; epithermal neutron activation analysis; radiochemical neutron activation analysis Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Vliv kryogenního mletí na homogenitu jódu v NIST SRM1548a Typical Diet

The reference material NIST SRM 1548a Typical Diet has a certified iodine mass fraction of 0.759±0.103 mg kg-1. The expanded uncertainty is rather large (relative value 13.6 %), thus the material does ...

Kameník, Jan; Kučera, Jan
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 - anglický
Study of fully automated analyzing system for the study of low-dose radiation effects on cellular radiobiology (poster) Klíčová slova: storage facility; dosimetry; irradiation Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
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 - anglický
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 Klíčová slova: NiTi shape memory alloy; neutron diffraction; phase analysis; light and electron microscopy Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
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

Study of mechanical properites of nanostructured polymer coatings prepared using plasma enhanced chemical vapor deposition
Buršíková, V.; Homola, V.; Peřina, Vratislav
2015 - anglický
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. Klíčová slova: PECVD; hexamethyldisiloxane; mechanical properties Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
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; Lavrentev, Vasyl; Vacík, Jiří
2015 - anglický
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. Klíčová slova: gas sensors; impedance measurement; nickel(II) oxide and copper(II) oxide Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
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; Lavrentev, Vasyl; Vacík, Jiří
Ústav jaderné fyziky, 2015

RESPONSE OF SURFACE MORPHOLOGY IN COBALT-FULLERENE MIXTURE FILMS UPON VARIATION OF THE METAL CONTENT
Lavrentev, Vasyl; Lavrenteva, Inna; Vacík, Jiří
2015 - anglický
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. Klíčová slova: Fullerene; Cobalt; mixture; roughness; surface; phase transformation Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
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 ...

Lavrentev, Vasyl; Lavrenteva, 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 - anglický
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. Klíčová slova: residual stress; neutron diffraction; steel welds Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
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 - český
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. Klíčová slova: carbon nanotubes; neutron activation analysis Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
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 - anglický
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. Klíčová slova: mercury; RNAA; Advanced Mercury Analyser Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
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 - anglický
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. Klíčová slova: superalloys; nano-precipitation; neutron scattering; STEM detector; TEM Dokument je dostupný na externích webových stránkách.
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

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