Nejdůležitější publikace 1. období (IRMA)

Tři nejdůležitější odborné publikace vydané během prvního období (do 31. března 2019). Seznam všech publikací výzkumného programu IRMA vydaných v rámci projektu CAAS najdete v předchozím příspěvku.

Antimony leaching from antimony-bearing ferric oxyhydroxides by filamentous fungi and biotransformation of ferric substrate
Author Martin Urík, Filip Polák, Marek Bujdoš, Marcel B. Miglierini, Barbora Milová-Žiaková, Bence Farkas, Zuzana Goneková, Hana Vojtková, Peter Matúš
Science of The Total Environment, Volume 664, 10 May 2019, Pages 683-689
Ferric oxyhydroxides are natural scavengers of antimony, thus, they contribute significantly to antimony immobilization in soils and sediments. Recent studies, however, usually omit microbial influence on geochemically stable antimony-ferric oxyhydroxide association. Therefore, we have evaluated fungal contribution to antimony mobility during static cultivation of common soil fungus Aspergillus niger in presence of ferric oxyhydroxides. Our results indicate distinguished effect of fungus on antimony distribution at two different antimony concentrations that were used for antimony pre-adsorbtion onto ferric oxyhydroxides prior to the inoculation. Approximately 36% of antimony was bioextracted by fungus from antimony bearing ferric oxyhydroxide after 14-day cultivation when the 8.9 mg·L−1 antimony concentration was used for pre-adsorption. However, no statistically significant change of antimony content in ferric oxyhydroxides was observed after cultivation when initial 48 mg·L−1 antimony concentration was used for pre-adsorption. As Mössbauer spectroscopy and XRD analysis indicated, nanosized akageneite, goethite, and lepidocrocite enhanced their crystallinity during cultivation, while hematite was identified only after the cultivation. Nevertheless, presence of ferric oxyhydroxides at both initial concentrations enabled transformation of antimony into volatile derivatives, and almost 9.5% of antimony was biovolatilized after cultivation. These results contribute significantly to environmental geochemistry of antimony-ferric oxyhydroxides association and highlight the importance of microbial activity in relation to ferric component of natural geochemical barriers.

Neutron activation analysis of Tibetan traditional medicinal pills at the VR-1 training reactor
Milan Stefanik, Lubomir Sklenka, Martin Cesnek, Marcel Miglierini, Jan Rataj
Radiation Physics and Chemistry, Available online 18 March 2019
The nuclear analytical methods provide the research techniques usually used in hard sciences such as physics, chemistry, engineering and technology, or natural sciences and technology, but it is very rare to use them in social sciences and humanities. The Czech Technical University (CTU) in Prague operates the VR-1 training reactor primarily focused on training students, nuclear engineering, reactor physics, and research; however, the utilization of this nuclear reactor has also been extended to humanities in recent years. In this direction, the research activities carried out at the reactor include the investigation of historical artefacts and testing of pharmaceutical and food industry samples. This contribution deals with the detailed study of traditional Tibetan medicinal pills by means of instrumental neutron activation analysis (NAA) at the VR-1 nuclear reactor. Three various kinds of Tibetan pills were irradiated by thermal neutrons in the experimental vertical channel at maximum reactor power (80 W), and irradiated samples were analysed using the semiconductor HPGe detector; saturated activities were obtained by means of the nuclear gamma-ray spectrometry, and subsequently the composition of the pills was determined (qualitative and quantitative analysis). The presence of Au, K, Fe, Na, As, Sr, Sb, and Hg was revealed in studied samples. The results presented in this paper show clearly that the low-power research reactor VR-1 is excellent tool for the neutron activation analysis experiments.

The effects of swift Xe ion bombardment on the amorphous structure of a VITROPERM type alloy
S. Michalik, M. Cesnek, M. Pavlovič, M. Miglierini
Journal of Alloys and Compounds, Available online 1 May 2019
The single crystalline Lu3Al5O12: Ce3+0.6%,Ca2+0.6% garnet films co-doped with Si4+ions were prepared by liquid phase epitaxy technique and their optical, luminescence, and scintillation properties were studied. The Ca co-doping into the Lu3Al5O12:Ce films resulted in a drastic acceleration of decay kinetics and decreased light yield due to the oxidization of Ce3+ into Ce4+ ions. The Si4+ co-doping regenerated the Ce3+ ions by virtue of charge compensation between Ca2+ and Si4+ions. The Ce valence changes were evidenced from the optical, photoluminescence and scintillation studies. Significant differences between the photoluminescence and scintillation properties were observed in Si + Ca co-doped samples. The influence of Si co-doping and the effect of Ce3+-to-Ce4+ ratio on the scintillation properties of Lu3Al5O12:Ce epitaxial garnet films is discussed.

Instrumentální radiační analytické metody (IRMA)

Koordinátor programu: prof. Ing. Ladislav Musílek, CSc.

Program integruje aktivity a staví na zkušenostech čtyř kateder FJFI ČVUT – dozimetrie a aplikace ionizujícího záření, inženýrství pevných látek, fyzikální elektroniky a jaderných reaktorů – v oblasti moderních instrumentálních metod zkoumání materiálové kompozice a
struktury.

Mezi unikátní pomůcky používané týmem patří například jaderný reaktor VR-1 řízený FJFI (http://reaktorvr1.eu/index.php). ČVUT spravuje také Van der Graafův urychlovač a využívá řadu analytických metod – například Mössbauerovu spektroskopii, PIXE a RBS analýzy, rentgenovou fluorescenční analýzu aj.

Práce v rámci výzkumného programu IRMA budou tematicky rozděleny do tří oblastí (podprogramů):

A) Detektory záření
B) Instrumentální analytické metody
C) Analýza materiálů užívající difrakci záření