Ternary Mn₂FeSi alloy was synthesized from pure elemental powders by mechanical alloying, using a high-energy planetary ball mill. The formation of an inverse-Heusler phase after 168 h of milling and subsequent annealing at 1173 K for 1.5 h was confirmed by X-ray diffraction. The diffractogram analysis yielded XA structure and the lattice parameter 0.5677 nm in a good agreement with the theoretically obtained value of 0.560 nm. The final powder was formed by particles of irregular shape and median diameter D50 of 3.8 μm and their agglomerates. The chemical analysis resulted in the mean composition of 49.0 at.% Mn, 25.6 at.% Fe and 25.4 at.% Si. At room temperature, the prepared samples featured a heterogeneous magnetic structure consisting of dominant paramagnetic phase confirmed by Mössbauer spectrometry and a weak ferro-/ferrimagnetic contribution detected by magnetization curves. From the field-cooled and zero-field-cooled curves the Néel temperature of 67 K was determined.

Innovative TiNbO_x nano-heterostructure oxides as promising catalysts in municipal wastewater treatment.

This study presents a rapid, environmentally friendly, and scalable activation method for 3D-printed poly­(lactic acid)/carbon black (PLA/CB) electrodes using atmospheric air plasma under ambient conditions. The goal was to optimize the plasma activation time and compare its efficiency with conventional activation techniques using N,N-dimethylformamide (DMF) and sodium hydroxide (NaOH). Surface morphology, chemical composition, wettability, and electrochemical performance were systematically evaluated through scanning electron microscopy (SEM), Raman spectroscopy, XPS, contact angle measurements, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Plasma treatment, as short as 5 s, effectively removed the PLA matrix from the electrode surface, enhanced surface roughness, hydrophilicity, and exposure of conductive carbon black particles, leading to increased electrochemical performance. Compared to chemical activation, 40 s of plasma activation yielded comparable performance with significantly shorter processing times (vs NaOH) and without hazardous solvents (such as DMF). Finally, the activated electrodes were successfully applied in the development, optimization, and validation of a novel electrochemical protocol for the determination of the antihypertensive drug amlodipine, revealing high sensitivity, a low limit of detection of 0.09 μM, precision (RSD of 6.6%), and recovery (97.1 and 105.4%) in pharmaceutical formulations. The findings demonstrate the promising potential of air plasma activation as a sustainable and efficient approach for preparing 3D-printed electrodes for analytical and sensing applications.