A polymeric precursor method was applied to synthesize catalysts of the general formula MFe₂O₄ (M = Co and Ni) in order to contribute to studies on ethylbenzene dehydrogenation in the presence of CO₂. The catalysts were characterized by TG, H₂-TPR, XRD, Mossbauer spectroscopy (MS), N₂ adsorption/desorption isotherms and TPD-CO₂. Investigations using XRD and MS revealed that the spinel structures of CoFe₂O₄ and NiFe₂O₄ phases were formed. The catalytic results suggested that materials with a spinel structure are particularly interesting for ethylbenzene dehydrogenation. Compared to the other catalysts synthesized the sample containing cobalt ferrite showed higher conversion and good styrene selectivity. The analysis of the spent catalyst (DRX) showed that the CoFe₂O₄ phase was stable under the reaction conditions and that a coke (TG) deposit was more pronounced for the NiFeSi.

Thin films of silver containing 0.3\char21{}1.5% Fe have been prepared by vapor codeposition. Depending on substrate temperature and iron concentration, we could systematically follow the formation of nanometer-size clusters of iron from initially dilute iron monomers. Samples were characterized via x-ray diffraction, resistivity, magnetization, susceptibility, and M\"ossbauer spectroscopic measurements. For samples with iron concentrations below 1% prepared at low temperatures, we find clear evidence for the Kondo effect. For higher concentrations, all studied samples reveal a nonmonotonic variation of resistivity with temperature, which can be understood by competing shielding of the cluster moments by conduction electron-spin scattering due to the Kondo effect and the magnetic coupling. The magnetic behavior can be best described with an ensemble of ferromagnetic particles. The magnetic freezing observed at low temperatures is assumed to be mainly controlled via the interparticle interactions mediated via conduction electron polarization, i.e., a Ruderman-Kittel-Kasuya-Yosida interaction.

In this work, AgNPs were synthesized using an anthocyanin extract from Peruvian purple potato INIA 328—Kulli papa. The anthocyanin extract was obtained through a conventional extraction with acidified ethanolic aqueous solvent. This extract acted as both a reducing and stabilizing agent for the reduction of silver ions. Optimization of synthesis parameters, including pH, reaction time, and silver nitrate (AgNO₃) concentration, led to the optimal formation of AgNPs at pH 10, with a reaction time of 30 min and an AgNO₃ concentration of 5 mM. Characterization techniques such as X-ray diffraction (XRD) and dynamic light scattering (DLS) revealed that the AgNPs had a crystallite size of 9.42 nm and a hydrodynamic diameter of 21.6 nm, with a zeta potential of −42.03 mV, indicating favorable colloidal stability. Fourier Transform Infrared (FTIR) analysis confirmed the presence of anthocyanin functional groups on the surface of the AgNPs, contributing to their stability. Furthermore, the bacterial activity of the AgNPs was evaluated by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). For E. coli, the MIC was 0.5 mM (0.05 mg/mL) and the MBC was 4.5 mM (0.49 mg/mL). Similarly, for S. aureus, the MIC was 0.5 mM (0.05 mg/mL) and the MBC was 4.0 mM (0.43 mg/mL). These results highlight the potential benefits of AgNPs synthesized from Peruvian purple potato anthocyanin extract, both in biomedical and environmental contexts.