In this study, the antibacterial activity of cerium oxide nanoparticles on two Gram-negative and three Gram-positive foodborne pathogens was investigated. CeO2 nanoparticles (CeO2 nps) were synthesized by a Wet Chemical Synthesis route, using the precipitation method and the Simultaneous Addition of reactants (WCS–SimAdd). The as-obtained precursor powders were investigated by thermal analysis (TG–DTA), to study their decomposition process and to understand the CeO2 nps formation. The composition, structure, and morphology of the thermally treated sample were investigated by FTIR, Raman spectroscopy, X-ray diffraction, TEM, and DLS. The cubic structure and average particle size ranging between 5 and 15 nm were evidenced. Optical absorption measurements (UV–Vis) reveal that the band gap of CeO2 is 2.61 eV, which is smaller than the band gap of bulk ceria. The antioxidant effect of CeO2 nps was determined, and the antibacterial test was carried out both in liquid and on solid growth media against five pathogenic microorganisms, namely Escherichia coli, Salmonella typhimurium, Listeria monocytogenes, Staphylococcus aureus, and Bacillus cereus. Cerium oxide nanoparticles showed growth inhibition toward all five pathogens tested with notable results. This paper highlights the perspectives for the synthesis of CeO2 nps with controlled structural and morphological characteristics and enhanced antibacterial properties, using a versatile and low-cost chemical solution method.

The introduction of artificial pinning sites in YBa2 Cu3O7−d (YBCO) epitaxial thin films has been\ud obtained by pulsed laser deposition ͑PLD͒ technique from YBCO-BaZrO3 ͑BZO͒ composite targets\ud with BZO concentration ranging from 2.5 to 7 mol %. The typical critical temperature, Tc , drop\ud observed in YBCO-secondary phase films grown by PLD has been successfully recovered by\ud increasing the deposition temperature. Transport properties analyses revealed improved pinning\ud force values for YBCO-BZO films for BZO concentration above 5 mol %. These films exhibited an\ud anomalous dual peak structure which has been ascribed to the presence of two pinning\ud contributions. The crossover field, Bm , separating these two pinning regimes has been observed to\ud be temperature independent suggesting the occurrence of the matching field effect. The measured\ud value of Bm agreed with the matching field value, B⌽ = Knd⌽0 , as evaluated from transmission\ud electron microscopy investigations. The mark of this phenomenon is retained down to 10 K, making\ud YBCO-BZO more performing than pristine YBCO films at applied magnetic fields below Bm in all\ud the temperature range inspected. On the contrary, in the high magnetic field range ͑above Bm͒, the\ud effectiveness of correlated pinning is progressively reduced on lowering the temperature suggesting\ud that at low temperatures the dominant pinning contribution arises from isotropic pinning centers

The structural and chemical evolution of propionate based low fluorine YBa2Cu3O7 − δ (YBCO) precursor during the conversion thermal treatment to obtain superconducting film has been investigated by both x-ray photoelectron and diffraction techniques in a set of partially converted films on SrTiO3 single crystals. The pyrolysis temperature within the range 400–480 °C mainly affects the copper valence state with an increase of the Cu2 + fraction with temperature with respect to the Cu1 + oxidation state. During the subsequent thermal treatment up to 700 °C, the reduction of fluorine content is mainly ascribed to the hydrolysis of YF3. At higher temperatures, Ba hydrolysis, Y2Cu2O5 and YBCO phase formation (nucleation at 700 °C and 725 °C, respectively) have been observed. The temperature dependences of the formation and decomposition of YBCO, Y2Cu2O5 and Ba-oxyfluoride were evaluated by x-ray diffraction measurements. The reaction path emerging from these analyses agrees with the one observed for YBCO films obtained with the standard MOD method based on metal tri-fluoroacetate precursors.

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