Antonino Rizzuti

Magnesium (Mg) alloys are promising candidates for biodegradable orthopedic implants, thanks to their mechanical properties and biocompatibility. Challenges related to the production of Mg-based prostheses are ( i ) the choice and the design of flexible manufacturing processes to produce complex shape components ( e.g., reproducing human bones) and ( ii ) the possibility of tailoring magnesium degradation rate in body fluids. Among flexible sheet metal forming processes, superplastic forming (SPF) allows to produce customized and complex parts characterized by a satisfying shape accuracy and surface quality. However, to be defined as a viable process for prostheses manufacturing, investigations about the effect of the processing route on the Mg alloy corrosion behavior as well as viable coatings for tailoring the implant degradation rate are needed. In the present work, electrochemical tests in simulated body environment were carried out on AZ31 samples before and after being subjected to the SPF process. Then, few micrometers thick hydroxyapatite coating obtained by Pulsed Laser Deposition (PLD) or by a phosphate chemical conversion (PCC) were investigated as possible solutions for controlling the degradation rate of the formed components. Chemical-physical characterizations (SEM analysis and Raman spectroscopy) and electrochemical tests (open circuit potential measurement, electrochemical impedances spectroscopy and polarization curves) were performed to assess the possible beneficial effect of the applied coating on the corrosion behavior of the superplastically formed AZ31 Mg components. Phosphate conversion coatings were effective in enhancing the corrosion resistance of AZ31 samples. This is evidenced by a two-order-of-magnitude increase in the overall impedance at low frequencies, from approximately 10 ² Ω ·cm ² for the untreated surface to 10 ⁴ Ω ·cm ² with the phosphate conversion coating. This significant increase directly indicates a substantial slowdown in the kinetics of magnesium dissolution and water reduction.

Non-targeted NMR is widely accepted as a powerful and robust analytical tool for food control. Nevertheless, standardized procedures based on validated methods are still needed when a non-targeted approach is adopted. Interlaboratory comparisons carried out in recent years have demonstrated the statistical equivalence of spectra generated by different instruments when the sample was prepared by the same operator. The present study focused on assessing the reproducibility of NMR spectra of the same matrix when different operators performed individually both the sample preparation and the measurements using their spectrometer. For this purpose, two independent laboratories prepared 63 tomato samples according to a previously optimized procedure and recorded the corresponding 1D ¹H NMR spectra. A classification model was built using the spectroscopic fingerprint data delivered by the two laboratories to assess the geographical origin of the tomato samples. The performance of the optimized statistical model was satisfactory, with a 97.62% correct sample classification rate. The results of this work support the suitability of NMR techniques in food control routines even when samples are prepared by different operators by using their equipment in independent laboratories.

The ionic exchange membranes represent a core component of redox flow batteries. Their features strongly affect the performance, durability, cost, and efficiency of these energy systems. Herein, the operating conditions of a lab-scale single-cell vanadium flow battery (VRFB) were optimized in terms of membrane physicochemical features and electrolyte composition, as a way to translate such conditions into a large-scale five-cell VRFB stack system. The effects of the sulfonation degree (SD) and the presence of a filler on the performances of sulfonated poly(ether ether ketone) (SPEEK) ion-selective membranes were investigated, using the commercial perfluorosulfonic-acid Nafion 115 membrane as a reference. Furthermore, the effect of a chloride-based electrolyte was evaluated by comparing it to the commonly used standard sulfuric acid electrolyte. Among the investigated membranes, the readily available SPEEK50-0 (SD = 50%; filler = 0%) resulted in it being permeable and selective to vanadium. Improved coulombic efficiency (93.4%) compared to that of Nafion 115 (88.9%) was achieved when SPEEK50-0, in combination with an optimized chloride-based electrolyte, was employed in a single-cell VRFB at a current density of 20 mA·cm⁻². The optimized conditions were successfully applied for the construction of a five-cell VRFB stack system, exhibiting a satisfactory coulombic efficiency of 94.5%.

The Champenoise method for the production of sparkling wines consists of an “in bottle” re-fermentation induced by a low number of commercial Saccharomyces cerevisiae strains. However, the limited use of these strains can induce flattening of the sensorial properties of the produced wine. Indeed, the volatile compounds produced by the yeasts during the fermentative process play an essential role in the constitution of the Bouchet sparkling wines prepared using indigenous grape varieties and, in particular, deriving from Apulia (Southern Italy), whose economic significance is constantly increasing [1]. To the best of our knowledge, only two investigations [²,³] have assessed the influence of autochthonous starter strains on the volatile profiles of sparkling wine. Moreover, no information exists on the oenological potential of the indigenous grape cv Maresco for the production of typical sparkling wine. This investigation evaluated the impact of the selected autochthonous yeast strains on the chemical properties of Maresco sparkling wines, applying a non-targeted metabolomics approach by the application of HPLC–HRMS and GC–MS techniques. Saccharomyces cerevisiae DV10 (Lallemand, Petaluma, CA, USA) was used as a control. The obtained findings indicated that previously selected native yeast strains influenced the amount of several fermentative compounds, i.e., polysaccharides, organic acids, phenolic acids, and lipids [⁴,⁵]. In order to reveal any grouping of wines based on the composition of volatile compounds and chemical data, as well as to identify the main components contained within each group, the data were subjected to principal component analysis (PCA). Additionally, the correlation matrix on HPLC–HRMS/GC–MS data was performed and a map was obtained, which represents a useful tool to monitor the different patterns of aroma release. The contribution supplies information that will support the modulation of the sensorial properties of regional sparkling wines obtained from typical autochthonous grape varieties using selected autochthonous microbial resources.

Fe₃O₄/CeO₂ nanocomposites were synthetized by coating magnetite seeds of different morphologies (hexagonal, spheroidal, quasi-spherical) with ceria, in ethylene glycol as solvothermal solvent. The synthesis was performed in the presence of microwave irradiation aiming to overcome the common disadvantages proper of the classic solvothermal/hydrothermal procedure. The obtained nanocomposites were calcined at the optimum temperature of 550 °C. The structure of the new nanomaterials was carefully investigated by IR, XRD, SEM, EDS and TEM analyses. The nanocomposites resulted to be constituted by CeO₂ nanoparticles distributed onto Fe₃O₄ seeds, that kept their pristine morphology. The new materials were used as catalysts for imine synthesis from benzyl alcohol and aniline. The highest imine conversion rate was obtained with Fe₃O₄/CeO₂, which was synthesized from Fe₃O₄ nanoparticles (hexagonal) obtained by microwave hydrothermal procedure in the absence of any organic additive (polyvinylpyrrolidone, trisodium citrate dihydrate or oleic acid). The catalyst could be easily removed from the reaction mixture with the help of an external magnet, and it was recycled for at least five runs with increasing catalytic activity.