Publications

Understanding the behavior of biomaterials under physiological conditions is essential for the development of new materials for implants and bone regeneration. This study addresses the critical need to evaluate how exposure to simulated body fluid (SBF) affects hydroxyapatite (HAp) and dextran-coated hydroxyapatite (HApDx) nanoparticles, which are widely considered for biomedical applications due to their bioactivity and biocompatibility. Structural, morphological, and surface property changes induced by SBF immersion were systematically investigated for the first time using advanced characterization techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), FT-Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and fractal and Minkowski functional analyses. The results revealed that SBF immersion significantly influenced both HAp and HApDx, leading to reduced crystallite sizes, surface smoothening, and enhanced structural homogeneity. FTIR and FT-Raman spectra indicated subtle structural modifications, while SEM and AFM analyses confirmed the formation of a biomimetic apatite layer and a decrease in surface roughness. These changes are indicative of improved bioactivity, suggesting enhanced potential for osteoconductivity and cellular interaction. Biological evaluations using MG63 osteoblast-like cells demonstrated favorable cell viability and adhesion across 24, 48, and 72 h, particularly for the samples immersed in SBF. AFM further confirmed that surface modifications supported the cell attachment and proliferation. Overall, our findings underscore the importance of SBF exposure in enhancing the physicochemical and biological performance of HAp-based materials, reinforcing their promise for biomedical applications.

In the present work, an essential advance in the preparation of novel nanocomposites based on functionalized V2O5 nanostructures with reduced graphene oxide by hydrothermal method, which has great potential for use in photocatalytic processes related to environmental remediation. XRD analysis confirmed V2O5 in an orthorhombic structure. SEM images showed transparent RGO layers well anchored onto the surface of the V2O5 with a homogeneous distribution. Raman spectroscopy further explained the hybridization and interaction between the components. The photocatalytic activity of Rhodamine-B in aqueous solutions has been studied upon irradiation with visible light. A high RhB degradation was obtained using the V2O5/RGO photocatalyst (82 %), compared to the degradation obtained with only V2O5 (60 %). First-principles Density Functional Theory (DFT) simulations reveal a strong interaction between V2O5 molecules and graphene surfaces, with an adsorption energy of -1.673 eV and a significant charge transfer of 0.367 e- to RGO. This interaction modifies the electronic structure, creating semi-metallic behavior near the Fermi level and enhancing catalytic activity through improved charge carrier dynamics and active sites for photocatalytic applications.

In this work a method in two steps for the preparation of the composites based on poly(ortho-toluidine) (POT) and the MoS2 and WS2 sheets was reported. In the first step, by ball-milling of mixtures of MoS2 and WS2 particles, the sheets of MoS2 and WS2 (MoS2: WS2) with weight ratio equal to 3:1, 1:1 and 1:3 were prepared. In the second step, the interaction in solid-state of the MoS2: WS2 samples with POT in emeraldine-base (POT-EB) and emeraldine-salt (POT-ES) was used to obtain composites of the type MoS2: WS2/POT-EB and MoS2: WS2/ POT-ES. Using X-ray diffraction (XRD), FTIR spectroscopy, Raman scattering and X-ray photoelectron spectroscopy (XPS), we demonstrate that: i) the ball-milling method can allow the preparation of the MoS2 and WS2 sheets with different stacking order, ii) the interaction of POT-EB with the MoS2: WS2 samples involves the transformation of some repeating units of the type EB into ES; and iii) the interaction of POT-ES with the MoS2: WS2 samples leads to the appearance of new positive charges onto macromolecular chains which are compensated by S2- ions. According to thermogravimetric analysis (TG) and differential scanning calorimetry (DSC), all samples are demonstrated to be stable up to 230 degrees C. Dielectric spectroscopy data reveal a complex dependence of DC electrical conductivity on frequency, temperature, and composite concentration. We use the apparent activation energy, defined as the derivative of the logarithm of conductivity with respect to the inverse temperature. The obtained results indicate that apparent activation energy is influenced by system composition via filling factors. The electrical properties of these heterogeneous materials are described using Lichtenecker's mixing laws. For components with similar electrical properties, the effective conductivity and apparent activation energy were determined as linear combinations of the individual conductivities and activation energies, respectively, weighted by the component concentrations. Our findings align with experimental data, offering a framework for understanding conductivity and activation energy in multi-component systems.

Within the framework of the EUROfusion Consortium, the Characterization of armour, heat sinks materials and joints sub-project of the Work Package Material (WP-MAT) has been dedicated to the development of different tungsten (W) monoblock mock-ups equipped with advanced materials for divertor target applications in the EUDEMO fusion reactor. Assessing the status of the relevant joining interfaces of these mock-ups, not only after fabrication but throughout the whole component lifetime, plays a key role in the qualification process. At the ENEA Special Technologies Laboratory (TES), a number of facilities have been built to perform non-destructive inspections of plasma-facing components for fusion applications by ultrasonic testing (UT). The present work reports on the results of the UT inspections assessing the structural integrity of the relevant joining interfaces of three small-scale mock-ups provided with advanced W armour materials, specifically W-matrix with W2C inclusions consolidated by Spark Plasma Sintering (SPS), K-doped rolled W and K-doped laminated W. The UT examinations are carried out after fabrication and after the high heat flux tests (HHFT) at the neutral beam facility GLADIS. All results confirm the high-quality joining achieved by HIP and HRP. During the HHF tests of mock-ups, after a few hundred HHFT cycles defects are detected at the joining interfaces, due to debonding, delamination and W material cracks mainly affecting the loaded zone. The ultrasonic pulse-echo technique provides not only the size and position of the defects in the plane orthogonal to the ultrasonic beam, but also their depth in the material. During the analysis, the probe is inserted inside the pipe and the mock-up is examined in a cylindrical configuration. The coupling medium (demineralized water) is poured only inside the pipe. The main inspection parameters and the piezoelectric probes are chosen to obtain the maximum resolution in accordance with the thickness and joining interfaces to be analyzed.

Biodegradable polymers like poly(epsilon-caprolactone) (PCL) are widely studied for their potential applications in biomedical and environmental fields. To enhance PCL's thermal, and bioactive properties, researchers have explored composite formulations with other polymers or bioactive compounds. Oleic acid (OA), a naturally occurring fatty acid, has been identified as a promising modifier. This study investigates the modification of PCL with OA using an eco-friendly catalyst to improve its functional properties. PCL was grafted with OA using Maghnite-H+, a heterogeneous solid catalyst clay activated via sulfuric acid treatment. A response surface methodology with a central composite design was applied to optimize synthesis parameters, including reaction temperature, duration, and catalyst concentration. The resulting composite was characterized using FTIR and NMR to confirm structural modifications, while its thermal stability was evaluated. Antioxidant activity was assessed using the DPPH radical scavenging assay, and antimicrobial potential was tested against various microorganisms. The PCL-OA composite exhibited enhanced antioxidant activity, with increased radical scavenging efficiency compared to unmodified PCL. Antimicrobial tests revealed strain-dependent effects, with improved inhibition observed in specific combinations of caprolactone, OA, and PCL-OA. The findings suggest that OA incorporation enhances PCL's bioactivity, making it a promising material for biomedical and packaging applications.

This study synthesized Mg-doped ZnO nanoparticles using the co-precipitation method with doping concentrations ranging from 2 % to 8 %. The structural, morphological, and optical properties of the synthesized nanoparticles were systematically characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and UV-Visible spectroscopy. XRD analysis confirmed the successful incorporation of Mg2+ ions into the ZnO lattice, evidenced by lattice parameter shifts and a significant reduction in crystallite size from 30.91 nm (pure ZnO) to 18.10 nm (6 % Mg doping). SEM images showed uniform morphology with reduced particle agglomeration at optimal doping levels, while FTIR analysis identified characteristic Zn-O and Mg-O bonding vibrations, confirming structural integrity. UV-Vis spectroscopy revealed strong absorbance in the UV region, with the band gap energy decreasing from 3.68 eV (pure ZnO) to 3.16 eV (6 % Mg doping), indicating enhanced optical properties conducive to improved photocatalytic performance. The photocatalytic activity of Mg-doped ZnO nanoparticles was evaluated by degrading Basic Fuchsin (BF) dye under UV light irradiation. The Mg-doped ZnO nanoparticles exhibited significantly enhanced photocatalytic performance compared to undoped ZnO, achieving a maximum degradation efficiency of 99.38 % at 6 % Mg doping within 100 min. Optimal photocatalytic conditions were observed at pH 6, using 0.1 g of catalyst and an initial dye concentration of 10 ppm. These enhancements were attributed to improved electron-hole pair separation and increased generation of reactive oxygen species (ROS), facilitated by the strategic incorporation of Mg. To complement the experimental findings, Density Functional Theory (DFT) simulations were performed, integrating the Conductor-like Screening Model for Realistic Solvation (COSMO-RS), Reduced Density Gradient (RDG), and Quantum Theory of Atoms in Molecules (QTAIM). The DFT analysis revealed enhanced charge separation, optimized electron transfer dynamics, and stronger adsorption interactions at Mg-doped sites, which promoted efficient ROS generation. The calculated valence band (VB) and conduction band (CB) edge potentials supported the formation of a Z-scheme heterojunction mechanism, enhancing charge separation and minimizing recombination. These theoretical insights aligned with the experimental observations, confirming that Mg doping effectively enhances photocatalytic efficiency by optimizing electronic interactions and promoting reactive surface dynamics. This integrated experimental and theoretical investigation demonstrates that Mgdoped ZnO nanoparticles exhibit superior photocatalytic properties, making them highly effective for environmental remediation applications, particularly in degrading organic pollutants in wastewater treatment. The study highlights the potential of Mg-doped ZnO as a promising photocatalyst for sustainable environmental solutions.

This study presents an environmentally friendly approach for synthesis Ag-TiO2 composite using pulsed reverse current (PRC) electrodeposition from green electrolytes, specifically deep eutectic solvents (DESs). The combination of PRC and DESs offers better control over nanoparticle synthesis while eliminating the need for toxic or expensive precursors, representing a significant advancement in sustainable nanomaterial synthesis. Different electrochemical parameters were adjusted, and their influence on the structure and morphology of the composite was investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). TEM analysis revealed that silver nanoparticles (Ag NPs) are attached to TiO2 nanopowder, with the coexistence of TiO2 and Ag further confirmed by XRD and XPS. The recorded UV-Vis diffuse reflectance spectra (DRS) displayed a broad peak in the range of 400 - 650 nm, associated with the localized surface plasmon resonance (LSPR) of Ag NPs on the semiconductor's surface. The photocatalytic activity of TiO2 nanopowder and Ag-TiO2 composite was evaluated based on the degradation of methyl orange (MO) dye under UV and visible light illumination. Our findings clearly demonstrated that the incorporation of Ag improved the photocatalytic efficiency. The mechanism of MO dye degradation was explored by using various scavengers, revealing that superoxide radicals (center dot O-2(-)) play a dominant role. Furthermore, the incorporation of Ag NPs significantly enhanced the antimicrobial activity of the oxide against both Gram-positive (B. subtilis) and Gram-negative (E.coli) strains.

Synthetic bone graft substitutes, including calcium phosphates (CaP), bioactive glasses (BG), and their composites with biopolymer matrices are attracting interest for bone tissue repair and regeneration. A key challenge is accurately replicating the biological structure and functionality of natural bone and optimizing the porous structure to match trabecular bone. This has been addressed by doping CaPs with therapeutic ions and using scaffolding methods like polymeric sponge replication and different additive manufacturing techniques. Biomimetic approaches employing naturally occurring porous biominerals with pore sizes comparable to those of trabecular bone, offer promising alternatives. This work reviews the hydrothermal transformation of cuttlefish bone (CB) into CaP scaffolds, while preserving its original porous structure, producing hydroxyapatite (HA, Ca10(PO4)6(OH)2), tricalcium phosphate (TCP, Ca3(PO4)2), and biphasic CaPs, both undoped and therapeutic ion-doped, constructs. Coating such biomimetic scaffolds with sol-gel-derived BG and biopolymers produces multifunctional bone graft substitutes with enhanced mechanical and biological properties. Moreover, polymeric coatings can act as drug reservoirs, enabling controlled release of therapeutic agents. The review highlights that integrating biomimetic strategies with advanced coating solutions holds great promise for creating multifunctional scaffolds that mimic nature and improve therapeutic outcomes in bone tissue engineering.

MgB2 is a perspective superconductor for many power applications. How this potential refers also to microwave or radiofrequency applications is still to be determined. Although its ultimate surface resistance in zero field is not competitive with conventional metallic superconductors, its strong pinning properties can favor RF applications in a dc magnetic field. Nonetheless, the RF response in the vortex state has been relatively less studied, as well as the effect of artificial pinning centers on the microwave surface resistance in the mixed state. In this paper we study the surface resistance of spark-plasma-sintered MgB2, with and without Te and cubic-BN (cBN) addition, in a dc magnetic field up to 1.2 T. We summarize previous results on pure MgB2, and we present new data on Te-and cBN-added MgB2. We use a two-tone dielectric-loaded resonator to measure the field-dependent surface resistance at 16.5 and 26.7 GHz in the temperature range from 10 K to T. By exploiting the simultaneous measurements at two frequencies, we extract the flux-flow resistivity, the pinning constant kp and the depinning frequency fp. The two-band nature of MgB2 affects the field dependence of the flux-flow resistivity. The microscopic superconducting state is not affected by the addition of artificial pinning centers, indicating that Te and cBN do not affect interband or intraband scattering. Pinning shows a measurable trend towards an increase in the Te-and cBN-added samples at higher temperatures and fields. We finally compare the results to those obtained in bulk Nb3Sn, also in view of possible in-field RF applications such as microwave cavity-based haloscopes.

Commercial melamine sponges were modified with a functional covalent organic framework (COF), and they were evaluated as adsorbents of divalent copper cations from aqueous solutions. A phosphazene unit successfully covered the surface of the melamine sponge, and the organic framework was subsequently formed through the nucleophilic substitution with 4,4 ' bipyridine. The covalent organic framework functionalized on the melamine sponge can detect and effectively adsorb copper compounds in aqueous solutions. Its selectivity toward the adsorption of copper was demonstrated through the presence of different metal salts. Four competitive metal cations, i.e., copper, nickel, iron, and calcium, were selected to confirm the preferential binding of copper on the COF-functionalized sponge. The outcome was determined through the studies of X-Ray Fluorescence elemental analysis, X-Ray Photoelectron Spectroscopy (XPS), and Electron Paramagnetic Resonance experiments. XRF reported a copper sorption capacity of 293 mu g cm-2, which is nearly nine times higher than the performance of the pristine sponge. Q-band EPR measurements demonstrated the presence of different coordination sites with different substituents for copper on the modified sponges, when the adsorption took place in an aqueous solution containing exclusively copper cations, while only one coordination, the favorable trigonal bipyramidal geometry, was obtained in the presence of additional metals.