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Fabrication of customized open-cell titanium foams by direct foaming for biomedical applications
(ELSEVIER, 2024-11-01) Oliver Urrutia, Carolina; Casas Luna, Mariano; Koledová, Zuzana; Slámečka, Karel; Zikmund, Tomáš; Kaiser, Jozef; Čelko, Ladislav; Montufar Jimenez, Edgar Benjamin
Titanium (Ti) foams offer a promising alternative for bone reconstruction and repair due to their high porosity and lower stiffness compared to solid metals, which improves in vivo osseointegration by reducing the stress shielding effect and allowing bone ingrowth. In this work, customized Ti foams were successfully fabricated for the first time at room temperature using a direct foaming method. Ti powder suspension with a water-soluble surfactant and environmentally friendly thickener was foamed by mechanical stirring. Then, 3D-printed moulds were utilized to achieve near-net shape foams, which were subsequently consolidated by sintering, thus avoiding the need for complex processing of molten Ti. The resulting Ti foams exhibited a cancellous-like open-cell structure, high porosity (> 80%), and a five times higher effective surface area than a 3D Ti mesh with a primitive cubic-based cell fabricated by additive manufacturing. In addition, the Ti foams exhibited similar mechanical properties to cancellous bone and facilitated the adhesion, proliferation, and maturation of human osteoblasts in vitro.
Triggering antibacterial activity of a common plant by biosorption of selected heavy metals
(SPRINGER, 2024-04-08) Kováčová, Maria; Yankovych, Halyna Bodnár; Augustyniak, Adrian; Casas Luna, Mariano; Remešová, Michaela; Findoráková, Lenka; Stahorský, Martin; Čelko, Ladislav; Baláž, Matej
The presented study proposes an efficient utilization of a common Thymus serpyllum L. (wild thyme) plant as a highly potent biosorbent of Cu(II) and Pb(II) ions and the efficient interaction of the copper-laden plant with two opportunistic bacteria. Apart from biochars that are commonly used for adsorption, here we report the direct use of native plant, which is potentially interesting also for soil remediation. The highest adsorption capacity for Cu(II) and Pb(II) ions (q e = 12.66 and 53.13 mg g-1, respectively) was achieved after 10 and 30 min of adsorption, respectively. Moreover, the Cu-laden plant was shown to be an efficient antibacterial agent against the bacteria Escherichia coli and Staphylococcus aureus, the results being slightly better in the former case. Such an activity is enabled only via the interaction of the adsorbed ions effectively distributed within the biological matrix of the plant with bacterial cells. Thus, the sustainable resource can be used both for the treatment of wastewater and, after an effective embedment of metal ions, for the fight against microbes.
Flow-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, Jan
In 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.
Control 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, Paola
Magnetic 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/).
Effect 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 Benjamin
Molybdenum 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/).

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