Pokročilé instrumentace a metody pro charakterizace materiálů

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    Laser-induced breakdown spectroscopy in space applications: Review and prospects
    (Elsevier, 2024-12-01) Saeidfirouzeh, Homa; Kubelík, Petr; Laitl, Vojtěch; Křivková, Anna; Vrábel, Jakub; Rammelkamp, Kristin; Schröder, Susanne; Gornushkin, Igor; Képeš, Erik; Žabka, Ján; Ferus, Martin; Pořízka, Pavel; Kaiser, Jozef
    This review describes the principles and summarizes the challenges of analytical methods based on optical emission spectroscopy (OES) in space applications, with a particular focus on Laser-Induced Breakdown Spectroscopy (LIBS). Over the past decade, LIBS has emerged as a powerful analytical technique for space exploration and In-Situ Resource Utilization (ISRU) of celestial bodies. Its implementation has been suggested for various segments of the Space Resources Value Chain, including prospecting, mining, and beneficiation. Current missions to Mars, including the ChemCam instrument on the Curiosity rover, the SuperCam on the Perseverance rover, and the MarSCoDe on the Zhurong rover, are considered flagship applications of LIBS. Despite neither the Pragyan rover nor the Vikram lander waking from the lunar night, the success of the Chandrayaan-3 mission marks another milestone in the development of LIBS instruments, with further missions, including commercial ones, anticipated. This paper reviews the deployment of LIBS payloads on Mars rovers, upcoming missions prospecting the Moon and asteroids, and LIBS analysis of meteorites. Additionally, it highlights the importance of data processing specific to space applications, emphasizing recent trends in transfer learning. Furthermore, LIBS combined with other spectroscopic techniques (e.g., Raman Spectroscopy, Mass Spectrometry, and Fourier-Transform Infrared Spectroscopy) represents an intriguing platform with comprehensive analytical capabilities. The review concludes by emphasizing the significance of LIBS-based contributions in advancing our understanding of celestial bodies and paving the way for future space exploration endeavors.
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    Interpreting neural networks trained to predict plasma temperature from optical emission spectra
    (ROYAL SOC CHEMISTRY, 2024-04-03) Képeš, Erik; Saeidfirouzeh, Homa; Laitl, Vojtěch; Vrábel, Jakub; Kubelík, Petr; Pořízka, Pavel; Ferus, Martin; Kaiser, Jozef
    We explore the application of artificial neural networks (ANNs) for predicting plasma temperatures in Laser-Induced Breakdown Spectroscopy (LIBS) analysis. Estimating plasma temperature from emission spectra is often challenging due to spectral interference and matrix effects. Traditional methods like the Boltzmann plot technique have limitations, both in applicability due to various matrix effects and in accuracy owing to the uncertainty of the underlying spectroscopic constants. Consequently, ANNs have already been successfully demonstrated as a viable alternative for plasma temperature prediction. We leverage synthetic data to isolate temperature effects from other factors and study the relationship between the LIBS spectra and temperature learnt by the ANN. We employ various post-hoc model interpretation techniques, including gradient-based methods, to verify that ANNs learn meaningful spectroscopic features for temperature prediction. Our findings demonstrate the potential of ANNs to learn complex relationships in LIBS spectra, offering a promising avenue for improved plasma temperature estimation and enhancing the overall accuracy of LIBS analysis. ANN can learn spectroscopic trends widely used by domain experts for plasma temperature estimation using emission spectra.
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    Lumbar Interbody Fusion Conducted on a Porcine Model with a Bioresorbable Ceramic/Biopolymer Hybrid Implant Enriched with Hyperstable Fibroblast Growth Factor 2
    (MDPI, 2021-06-25) Krtička, Milan; Plánka, Ladislav; Vojtová, Lucy; Nekuda, Vladimír; Šťastný, Přemysl; Sedláček, Radek; Břínek, Adam; Kavková, Michaela; Göpfert, Eduard; Hedvičáková, Věra; Rampichová, Michaela; Křen, Leoš; Lišková, Květoslava; Ira, Daniel; Matulová, Jana; Suchý, Tomáš; Zikmund, Tomáš; Kaiser, Jozef; Starý, David; Faldyna, Martin; Trunec, Martin
    An experimental animal study was designed to investigate the intervertebral fusion efficiency and safety of a bioresorbable ceramic/biopolymer hybrid implant enriched with FGF2-STAB(R) in comparison with a tricortical bone autograft used as a gold standard. Twenty-four experimental pigs underwent L2/3 discectomy with implantation of either the tricortical iliac crest bone autograft or the bioresorbable hybrid implant (BHI) followed by lateral intervertebral fixation. The quality of spinal fusion was assessed by micro-computed tomography (micro-CT), biomechanical testing, and histological examination at both 8 and 16 weeks after the surgery.
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    Study of plasma activated water effect on heavy metal bioaccumulation by Cannabis sativa Using Laser-Induced Breakdown Spectroscopy
    (Elsevier, 2024-09-15) Čechová, Ludmila; Holub, Daniel; Šimoníková, Lucie; Modlitbová, Pavlína; Novotný, Karel; Pořízka, Pavel; Kozáková, Zdenka; Krčma, František; Kaiser, Jozef
    Contamination of the environment with toxic metals such as cadmium or lead is a worldwide issue. The accumulator of metals Cannabis sativa L. has potential to be utilized in phytoremediation, which is an environmentally friendly way of soil decontamination. Novel non-thermal plasma-based technologies may be a helpful tool in this process. Plasma activated water (PAW), prepared by contact of gaseous plasma with water, contains reactive oxygen and nitrogen species, which enhance the growth of plants. In this study, C. sativa was grown in a short-term toxicity test in a medium which consisted of plasma activated water prepared by dielectric barrier discharge with liquid electrode and different concentrations of cadmium or lead. Application of PAW on heavy metal contaminated C. sativa resulted in increased growth under Pb contamination as was determined by ecotoxicology tests. Furthermore, the PAW influence on the bioaccumulation of these metals as well as the influence on the nutrient composition of plants was studied primarily by applying Laser-induced breakdown spectroscopy (LIBS). The LIBS elemental maps show that C. sativa accumulates heavy metals mainly in the roots. The results present a new proof-of-concept in which PAW could be used to improve the growth of plants in heavy metal contaminated environment, while LIBS can be implemented to study the phytoremediation efficiency.
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    Characterization of GaAs Solar Cells under Supercontinuum Long-Time Illumination
    (MDPI, 2021-01-19) Papež, Nikola; Dallaev, Rashid; Kaspar, Pavel; Sobola, Dinara; Škarvada, Pavel; Ţălu, Ştefan; Ramazanov, Shikhgasan; Nebojsa, Alois
    This work is dedicated to the description of the degradation of GaAs solar cells under continuous laser irradiation. Constant and strong exposure of the solar cell was performed over two months. Time-dependent electrical characteristics are presented. The structure of the solar cells was studied at the first and last stages of degradation test. The data from Raman spectroscopy, reflectometry, and secondary ion mass spectrometry confirm displacement of titanium and aluminum atoms. X-ray photoelectron spectroscopy showed a slight redistribution of oxygen bonds in the anti-corrosion coating.