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- ItemFlow-through Gas Phase Photocatalysis Using TiO2 Nanotubes on Wirelessly Anodized 3D-Printed TiNb Meshes(American Chemical Society, 2023-07-12) Sopha, Hanna Ingrid; Kashimbetova, Adelia; Baudys, Michal; Chennam, Pavan Kumar; Sepúlveda Sepúlveda, Lina Marcela; Rusek, Jakub; Kolíbalová, Eva; Čelko, Ladislav; Montufar Jimenez, Edgar Benjamin; Krýsa, Josef; Macák, JanIn this work, for the first time 3D Ti-Nb meshes of differentcomposition,i.e., Ti, Ti-1Nb, Ti-5Nb, and Ti-10 Nb, were produced by direct inkwriting. This additive manufacturing method allows tuning of the meshcomposition by simple blending of pure Ti and Nb powders. The 3D meshesare extremely robust with a high compressive strength, giving potentialuse in photocatalytic flow-through systems. After successful wirelessanodization of the 3D meshes toward Nb-doped TiO2 nanotube(TNT) layers using bipolar electrochemistry, they were employed forthe first time for photocatalytic degradation of acetaldehyde in aflow-through reactor built based on ISO standards. Nb-doped TNT layerswith low concentrations of Nb show superior photocatalytic performancecompared with nondoped TNT layers due to the lower amount of recombinationsurface centers. High concentrations of Nb lead to an increased numberof recombination centers within the TNT layers and reduce the photocatalyticdegradation rates.
- ItemControl of magnetic vortex states in FeGa microdisks: Experiments and micromagnetics(Vietnam National University, 2023-06-14) Pradhan, Gajanan; Celegato, Federica; Madri, Alessandro; Coisson, Marco; Barrera, Gabriele; Mikuličková, Lenka; Arregi Uribeetxebarria, Jon Ander; Čelko, Ladislav; Uhlíř, Vojtěch; Rizzi, Paola; Tiberto, PaolaMagnetic vortices have been an interesting element in the past decades due to their flux-closure domain structures which can be stabilized at ground states in soft ferromagnetic microstructures. In this work, vortex states are shown to be nucleated and stabilized in Fe80Ga20 and Fe70Ga30 disks, which can be upcoming candidate for applications in strain-induced electric field control of magnetic states owing the high magnetostriction of the alloy. The magnetization reversal in the disks occurs by the formation vortex, double vortex or S-domain state. Micromagnetic simulations have been performed using the FeGa material parameters and the simulated magnetic states are in good agreement with the experi-mental results. The studies performed here can be essential for the use of FeGa alloy in low-power electronics.& COPY; 2023 Vietnam National University, Hanoi. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
- ItemEffect of powder milling on sintering behavior and monotonic and cyclic mechanical properties of Mo and Mo-Si lattices produced by direct ink writing(Elsevier, 2023-10-05) Tkachenko, Serhii; Slámečka, Karel; Oliver Urrutia, Carolina; Ksenzova, Olha; Bednaříková, Vendula; Remešová, Michaela; Dvořák, Karel; Baláž, Matej; Deák, Andréa; Kachlík, Martin; Čelko, Ladislav; Montufar Jimenez, Edgar BenjaminMolybdenum is a refractory metal regarded as a promising basis for producing high-temperature components. However, the potential of manufacturing molybdenum-based structures by direct ink writing (DIW) has not been explored. In this study, three-dimensional porous molybdenum (Mo) and molybdenum-silicon (Mo-Si) composite lattices were fabricated using DIW with non-milled and milled powders. The effects of Mo powder morphology (resulting from milling) and chemical composition (alloying Mo with 3 and 10 wt% of Si) on the microstructure, phase composition, and static and cyclic compression properties at room temperature were investigated. Lattices fabricated from commercial spherical Mo powder exhibited the highest intra-filament porosity. Conversely, lattices fabricated from milled Mo powder were denser and had higher compressive strength, offset stress, and quasi-elastic gradient. Alloying Mo with Si during sintering resulted in composite lattices with Mo thorn Mo3Si microstructure. A low content of Mo3Si slightly decreased monotonic compression properties but did not affect the cyclic compression response compared to Mo lattices made from milled powder. In contrast, a high content of Mo3Si produced quasi-brittle lattices with reduced compressive strength and increased damage accumulation during cyclic loading. The cyclic behavior of all lattices was characterized by a ratcheting-dominated stress-strain response. Lattices fabricated from milled Mo and milled Mo-3 wt.%Si powders demonstrated superior performance compared to those fabricated from commercial spherical Mo and milled Mo-10 wt%Si powders. The results suggest that using milled powders can enhance the mechanical reliability and promote the use of DIW as preferred additive manufacturing technology for the fabrication of Mo-Si composite lattices. (c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
- ItemAerogel-Based Materials in Bone and Cartilage Tissue Engineering-A Review with Future Implications(MDPI, 2023-09-13) Lázár, István; Čelko, Ladislav; Menelaou, MelitaAerogels are fascinating solid materials known for their highly porous nanostructure and exceptional physical, chemical, and mechanical properties. They show great promise in various technological and biomedical applications, including tissue engineering, and bone and cartilage substitution. To evaluate the bioactivity of bone substitutes, researchers typically conduct in vitro tests using simulated body fluids and specific cell lines, while in vivo testing involves the study of materials in different animal species. In this context, our primary focus is to investigate the applications of different types of aerogels, considering their specific materials, microstructure, and porosity in the field of bone and cartilage tissue engineering. From clinically approved materials to experimental aerogels, we present a comprehensive list and summary of various aerogel building blocks and their biological activities. Additionally, we explore how the complexity of aerogel scaffolds influences their in vivo performance, ranging from simple single-component or hybrid aerogels to more intricate and organized structures. We also discuss commonly used formulation and drying methods in aerogel chemistry, including molding, freeze casting, supercritical foaming, freeze drying, subcritical, and supercritical drying techniques. These techniques play a crucial role in shaping aerogels for specific applications. Alongside the progress made, we acknowledge the challenges ahead and assess the near and far future of aerogel-based hard tissue engineering materials, as well as their potential connection with emerging healing techniques.
- ItemThe first solid-state route to luminescent Au(I)-glutathionate and its pH-controlled transformation into ultrasmall oligomeric Au10-12(SG)10-12 nanoclusters for application in cancer radiotheraphy(Frontiers Media, 2023-06-05) Deák, Andréa; Szabó, Pál T.; Bednaříková, Vendula; Cihlář, Jaroslav; Demeter, Attila; Remešová, Michaela; Colacino, Evelina; Čelko, LadislavThere is still a need for synthetic approaches that are much faster, easier to scale up, more robust and efficient for generating gold(I)-thiolates that can be easily converted into gold-thiolate nanoclusters. Mechanochemical methods can offer significantly reduced reaction times, increased yields and straightforward recovery of the product, compared to the solution-based reactions. For the first time, a new simple, rapid and efficient mechanochemical redox method in a ball-mill was developed to produce the highly luminescent, pH-responsive Au(I)-glutathionate, [Au(SG)]( n ). The efficient productivity of the mechanochemical redox reaction afforded orange luminescent [Au(SG)]( n ) in isolable amounts (mg scale), usually not achieved by more conventional methods in solution. Then, ultrasmall oligomeric Au10-12(SG)(10-12) nanoclusters were prepared by pH-triggered dissociation of [Au(SG)]( n ). The pH-stimulated dissociation of the Au(I)-glutathionate complex provides a time-efficient synthesis of oligomeric Au10-12(SG)(10-12) nanoclusters, it avoids high-temperature heating or the addition of harmful reducing agent (e.g., carbon monoxide). Therefore, we present herein a new and eco-friendly methodology to access oligomeric glutathione-based gold nanoclusters, already finding applications in biomedical field as efficient radiosensitizers in cancer radiotherapy.