Ústav fyzikálního inženýrství

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Statistical behaviour of laser-induced plasma and its complementary characteristic signals
(Royal Society of Chemistry, 2024-09-04) Buday, Jakub; Holub, Daniel; Pořízka, Pavel; Kaiser, Jozef
In this work, we present a study aimed at the statistical distribution of characteristic signals of laser-induced plasmas. This work mainly focuses on observing statistical distribution for repetitive measurement of spectra, plasma plume imaging, and sound intensity. These were captured by using various laser irradiances, spanning between 1.72 and 6.25 GW cm2 for a 266 nm laser. Their distributions were fitted by Gaussian, generalized extreme value (GEV), and Burr distributions, as typical representation models used in LIBS. These were compared using the Kolmogorov–Smirnov (KS) test by its null hypothesis on whether these models are suitable or fail to describe the statistical distribution of the data. The behavior of the data distribution has shown a certain connection to the plasma plume temperature. This was observed for all the used ablation energies. Performances of the statistical models were further compared in the outlier filtering process, where the relative standard deviation of the filtered data was observed. The results presented in this work suggest that an appropriate selection of a statistical model for the data representation can lead to an improvement in the LIBS performance.
Technology and provenience of the oldest pottery in the northern Pannonian Basin indicates its affiliation to hunter-gatherers
(Springer Nature, 2024-08-20) Petřík, Jan; Slavíček, Karel; Adameková, Katarína; Jaques, Victory; Košťál, Martin; Tóth, Peter; Petr, Libor; Všianský, Dalibor; Zikmund, Tomáš; Kaiser, Jozef; Bátora, Jozef; Bickle, Penny
Consensus holds that pottery technology came to Central Europe from the Northern Balkans with independent pottery traditions existing concurrently in Eastern Europe. An unusual grass-tempered pottery dating back to around 5800 cal BC found in lake sediments at Santovka, Slovakia, predated the earliest known Neolithic pottery in the region (similar to 5500 cal BC), suggesting unexplored narratives of pottery introduction. Analyses of the pottery's technology, origin, and grass temper shedding light on ceramic traditions' spread can unveil mobility patterns and community lifestyles. Our findings indicate a non-local provenance, low temperature firing, Festugc sp. grass temper and unique rectangular or cylindrical vessel shapes which align with Eastern European hunter-gatherer practices. Moreover, the pottery style and technology have no analogies in the contemporary Danubian pottery traditions and have more similarities to those of the Eastern traditions. The pottery's raw materials likely originated from distant areas, indicating extensive territorial access for its creators. Our findings imply late Mesolithic hunter-gatherers as the probable artisans and with implications for the site's significance in the late Mesolithic landscape.
Accelerating the Laser-Induced Phase Transition in Nanostructured FeRh via Plasmonic Absorption
(WILEY-V C H VERLAG GMBH, 2024-08-01) Mattern, Maximilian; Pudell, Jan Etienne; Arregi Uribeetxebarria, Jon Ander; Zlámal, Jakub; Kalousek, Radek; Uhlíř, Vojtěch; Rössle, Matti; Bargheer, Matias
By ultrafast x-ray diffraction (UXRD), it is shown that the laser-induced magnetostructural phase transition in FeRh nanoislands proceeds faster and more complete than in continuous films. An intrinsic 8 ps timescale is observed for the nucleation of ferromagnetic (FM) domains in the optically excited fraction of both types of samples. For the continuous film, the substrate-near regions are not directly exposed to light and are only slowly transformed to the FM state after heating above the transition temperature via near-equilibrium heat transport. Numerical modeling of the absorption in the investigated nanoislands reveals a strong plasmonic contribution near the FeRh/MgO interface. The larger absorption and the optical excitation of the electrons in nearly the entire volume of the nanoislands enables a rapid phase transition throughout the entire volume at the intrinsic nucleation timescale. Nanostructuring FeRh thin films by solid state dewetting make the laser-induced antiferromagnetic to ferromagnetic phase transition more efficient and speed the switching up to the intrinsic timescale. Ultrafast x-ray diffraction experiments directly measure the structural order parameter averaged over the entire film. Finite element modeling reveals the enhanced plasmonic light absorption near the substrate as the crucial factor. image
Assessing the ecological consequences of biodegradable plastics: Acute, chronic and multigenerational impacts of poly-3-hydroxybutyrate microplastics on freshwater invertebrate Daphnia magna
(CELL PRESS, 2024-08-30) Procházková, Petra; Kalčíková, Gabriela; Maršálková, Eliška; Brtnický, Martin; Zlámalová Gargošová, Helena; Kučerík, Jiří
Microplastics, pervasive contaminants in freshwater ecosystems, have raised ecological concerns. Efforts are underway to substitute conventional plastics with biodegradable alternatives that should be more easily decomposed in the environment. However, the biodegradation of these alternatives depends on specific conditions such as temperature, humidity, pH, and microorganisms, which are not always met. Consequently, these biodegradable alternatives can also fragment and generate microplastics, which can be ingested and affect biota. In this study, we investigated the acute, chronic, and multigenerational effects of two fractions (particles <63 mu m and particles <125 mu m) of biodegradable poly-3-hydroxybutyrate (P3HB) at varying concentrations on the inhibition, mortality, reproduction activity, and growth of the freshwater invertebrate Daphnia magna. No acute effects were observed for either size fraction. However, during chronic and multigenerational experiments, an increase in the concentration of P3HB microplastics corresponded with increased mortality, reduced reproductive activity, and slower growth among the mother organisms. Given the important role of D. magna in the food chain, these findings suggest that biodegradable microplastics may indeed negatively affect freshwater ecosystems.
Advancing microplastic detection in zebrafish with micro computed tomography: A novel approach to revealing microplastic distribution in organisms
(Elsevier, 2025-05-05) Parobková, Viktória; Maleček, Lukáš; Zemek, Marek; Kalčíková, Gabriela; Vykypělová, Michaela; Buchtová, Marcela; Adamovský, Ondřej; Zikmund, Tomáš; Kaiser, Jozef
The analysis of microplastics with current spectroscopic and pyrolytic methods is reaching its limits, especially with regard to detailed spatial distribution in biological tissues. This limitation hampers a comprehensive understanding of the effects of microplastics on organisms. Therefore, there is a pressing need to expand the analytical approaches to study microplastics in biota. In this context, the aim of this study was to test the applicability of non-destructive 3D imaging using X-ray micro-computed tomography (microCT) for the detection of microplastics in fish. Zebrafish (Danio rerio) were gavaged with polyethylene spherical microplastics (30-110 mu m) and the distribution of microplastics in the gut was investigated using microCT. The results showed that the particle size distribution determined by microCT closely matched the data from conventional laser diffraction analysis. In addition, microCT was able to detect microplastics in spiked fish tissue and provide precise localization data by tracing particles of known type and shape. MicroCT offers a novel approach for tracking microplastics in organisms and enables accurate sizing without compromising the integrity of the tissue under investigation. It therefore represents a valuable addition to spectroscopic methods, which are widely used for the detection of microplastics based on their chemical composition but do not provide data on their spatial distribution.

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