Sebastian Alin Porav

Nanotechnology has emerged as a highly focused field of research due to the unique properties of nanometric materials, particularly their large specific surface areas and excellent adsorption capabilities. This study investigated the synthesis of materials based on graphene oxide (GO) functionalized with different metal oxides (MnO₂, Fe₃O₄, CuO, NiO), with potential applications in water decontamination. The morphological, structural, and compositional properties of these nanocomposites were extensively characterized using different experimental techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometry (VSM) for magnetic property evaluation. Preliminary adsorption tests were performed for the removal of pesticides and drugs from aqueous solutions. The synthesized materials demonstrated a higher affinity for selected pesticides compared to drugs. The best removal efficiencies were 98.59% for cymoxanil, 97.93% for triadimefon, 63.33% for sulfamethoxazole, and 99.59% for diclofenac. The results indicate that the functionalization of GO with metal oxides modifies the material’s structure, increasing its potential for environmental applications such as water purification.

Shape memory alloys, especially ferromagnetic shape memory alloys, are interesting new materials for the manufacturing of stents. Iron–palladium alloys in particular can be used to manufacture self-expanding temporary stents due to their optimum rate of degradation, which is between that of magnesium and pure iron, two metals commonly used in temporary stent research. In order to avoid blood clotting upon the introduction of the stent, they are often coated with anticoagulants. In this study, sulfated pectin, a heparin mimetic, was synthesized in different ways and used as coating on multiple iron–palladium alloys. The static and dynamic prothrombin time (PT) and activated partial thromboplastin time (APTT) of the prepared materials were compared to samples uncoated or coated with polyethylene glycol. While no large differences were observed in the prothrombin time measurements, the activated partial thromboplastin time increased significantly with all alloys coated with sulfated pectin. Aside from that, sulfated pectin synthesized by different methods also caused slight changes in the activated partial thromboplastin time. These findings show that iron–palladium alloys can be coated with anticoagulants to improve their utility as material for temporary stents. Sulfated pectin was characterized by nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR) spectroscopy, and the coated alloys by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX).

Four N-doped graphene materials with a nitrogen content ranging from 8.34 to 13.1 wt.% are prepared by the ball milling method. This method represents an eco-friendly mechanochemical process that can be easily adapted for industrial-scale productivity and allows both the exfoliation of graphite and the synthesis of large quantities of functionalized graphene. These materials are characterized by transmission and scanning electron microscopy, thermogravimetry measurements, X-ray powder diffraction, X-ray photoelectron and Raman spectroscopy, and then, are tested towards the oxygen reduction reaction by cyclic voltammetry and rotating disk electrode methods. Their responses towards ORR are analysed in correlation with their properties and use for the best ORR catalyst identification. However, even though the mechanochemical procedure and the characterization techniques are clean and green methods (i.e., water is the only solvent used for these syntheses and investigations), they are time consuming and, generally, a low number of materials can be prepared, characterized and tested. In order to eliminate some of these limitations, the use of regression learner and reverse engineering methods are proposed for facilitating the optimization of the synthesis conditions and the materials’ design. Thus, the machine learning algorithms are applied to data containing the synthesis parameters, the results obtained from different characterization techniques and the materials response towards ORR to quickly provide predictions that allow the best synthesis conditions or the best electrocatalysts’ identification.

Understanding the energy transfer in phycobilisomes extracted from cyanobacteria can be used for building biomimetic hybrid systems for optimized solar energy collection and photocurrent amplification. In this paper, we applied time-resolved absorption and fluorescence spectroscopy to investigate the ultrafast dynamics in a hemidiscoidal phycobilisome obtained from Arthrospira platensis. We obtained the steady-state and time-resolved optical properties and identified the possible pathways of the excitation energy transfer in the phycobilisome and its components, phycocyanin and allophycocyanin. The transient absorption data were studied using global analysis and revealed the existence of ultrafast kinetics down to 850 fs in the phycobilisome. The fluorescence lifetimes in the nanosecond time-scale assigned to the final emitters in each sample were obtained from the time-correlated single photon counting fluorescence experiments.

Raman scattering and its particular effect, surface-enhanced Raman scattering (SERS), are whole-organism fingerprinting spectroscopic techniques that gain more and more popularity in bacterial detection. In this work, two relevant Gram-positive bacteria species, Lactobacillus casei (L. casei) and Listeria monocytogenes (L. monocytogenes) were characterized based on their Raman and SERS spectral fingerprints. The SERS spectra were used to identify the biochemical structures of the bacterial cell wall. Two synthesis methods of the SERS-active nanomaterials were used and the recorded spectra were analyzed. L. casei and L. monocytogenes were successfully discriminated by applying Principal Component Analysis (PCA) to their specific spectral data.