Publications

Cu2SnS3 thin films emerged as promising materials for sustainable photovoltaics due to their earth-abundant constituents and great optoelectronic properties. The formation of secondary phases during synthesis poses challenges to achieving efficient performances. This study investigates the impact of secondary on the of CTS films.

In this study, we evaluate the feasibility of using quantum neural networks for classifying gravitational waveforms, using both simulators and quantum computers. The analysis is quite interdisciplinary in its nature, combining knowledge involving astrophysics, quantum information as well as quantum and classical machine learning. We showed that the quantum classifiers and hybrid classical-quantum layers give highly accurate results when tested on a simple dataset and ran on a simulator; also, adding a quantum layer to poorly performing classical neural network can highly improve its accuracy. When running on a real quantum computer, error minimizing algorithms need to be implemented in order to obtain a satisfying accuracy.

Proteins are vital components of living cells and the loss of their native functions has been associated with a wide variety of medical conditions. From this point of view, investigation of the protein microenvironment is crucial to support the development of therapeutic approaches capable of ensuring cellular functions. Therefore, analytical assays for the detection, quantification, and characterization of proteins, drugs, and protein-drug complexes play an essential role in fundamental research and clinical applications. Electrochemistry arises as an alternative methodology for fast assessment of proteins and drugs and is attractive due to the adaptability to miniaturization and scalability of electroanalytical devices, which then can be further employed as strategies towards personalized medical care. Thus, this review summarizes electrochemical investigations in the past 10 years on protein-based analytical devices and biosensors. A general overview of electrochemical assays that integrate proteins with nanostructured materials and conductive polymers is presented. Applications of electrochemical assays and biosensors were divided into four categories. First, those designed for drug screening strategies that focus on targeting specific intracellular, extracellular, or membrane protein subdomains to modulate their functions, aggregation/misfolding of proteins, and protein degradation pathways. Then, drug metabolism assays that involve mimicking natural metabolic pathways to identify potential safety and efficacy issues related to a drug or its metabolites. The third was dedicated to electrochemical drug delivery systems with anchored drugs in the form of bioconjugates, while the fourth was dedicated to electroanalytical methodologies for quantitative drug assays, where the electroactivity of the target species is often used to correlate the electrochemical signal to their concentration.

In this study, we characterized the temperature-dependent electrical conductivity properties of undoped and lightly doped bulk InSb samples using terahertz time-domain spectroscopy. We obtained the permittivity spectra at low temperatures and analyzed the carrier density and mobility by fitting the spectra to the Drude model. Based on our analysis, we show the temperature dependence of the optical constants and explain the underlying physical mechanisms for the observed behavior. Our results provide important insights into the electronic properties of InSb.

Mg2Si thermoelectric compound was obtained by dry and wet (isohexane and benzene) mechanical alloying route. The Mg2Si compound was characterised by X-ray diffraction, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), laser particle size analysis and thermoelectric measurements. After 14 h of milling, the complete reaction of the elements is achieved by both routes. The powders particle size distribution obtained after 14 h of dry or wet milling (using benzene) reveals a bimodal curve. The wet milling moves the particle size distribution towards smaller particle sizes. The SEM analysis confirms the results of particles size analysis. DSC analyses performed for samples milled up to 14 h present stress relief and recrystallisation thermal events. For the benzene wet-milled sample, the DSC curve shows an additional thermal event at 350'C, associated with benzene removal. Thermoelectric properties were determined on spark plasma sintered compacts. The milling process with benzene leads to a higher value of Seebeck coefficient (z580 mV/K). The electrical conductivity is low at room temperature and increases exponentially with temperature. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

In this work, polyvinylidene fluoride (PVDF) fibres loaded with mineral powders, such as titanium dioxide (TiO2), barium titanate (BaTiO3), and calcium magnesium silicate (CaxMgSi2Oy), were prepared by electrospinning polymeric suspensions containing 20 wt.% PVDF and 3 wt.% powder. The piezoelectric polymer was combined with powders having antibacterial, piezoelectric, or bioactive properties, respectively, in the desire to obtain multifunctional materials compatible with the requirements of the medical field. All powders were characterized in terms of morphology and crystalline structure, which confirmed the nanometric character of TiO2 samples and micrometric one for the other two, as well as the lower crystallite size for TiO2 specimens as against BaTiO3 and CaxMgSi2Oy. The final fibrous scaffolds were homogeneous, composed of individual fibres with a diameter below 1 mu m and decorated with aggregates of inorganic particles, placed either inside the fibres or attached to their surface. The biological evaluation demonstrated the superiority of the composites towards the plain polymer in terms of cell viability.

Dynamic hysteresis effects have been long known to occur in the current density-voltage characteristics of perovskite solar cells, with the ionic migration being identified as the primary factor. The hysteretic effects impacted early studies by the uncertainty in the evaluation of the power conversion efficiency, while currently, potential links to degradation mechanisms are the focus. Therefore, understanding ion migration is a central goal, typically addressed by performing a combined large and small signal analysis. The reported large capacitive and inductive effects created controversies with respect to the underlying mechanisms, yielding essentially two classes of models, one based on the large accumulation capacitances and the other based on the ionic modulation of the collected current. We introduce here an equivalent circuit model and interpret these phenomena in terms of recombination current modulation, identifying the distinct contributions from ion current and ionic charge accumulations. These contributions to the recombination current are associated with capacitive and inductive effects, respectively, and we corroborate the numerical simulations with electrochemical impedance spectroscopy measurements. These show the role of the recombination currents of photogenerated carriers in producing both capacitive and inductive effects as the illumination is varied. Moreover, we provide a bridging point between the two classes of models and suggest a framework of investigation of defect states based on the observed inductive behavior, which would further aid the mitigation of the degradation effects.

The evaluation of corrosion inhibition of mild steel (M-S) in 1.0 M HCl solution in the absence and the presence of different concentrations of (E)-3-(5-bromo-2-hydroxystyryl)quinoxalin-2(1H)-one (FR178) and (E)-3-(5-fluoro-2-hydroxystyryl)quinoxalin-2(1H)-one (FR179) was studied by electrochemical,and theoretical measurements. These organic inhibitors have proven to be effective corrosion inhibitors for the protection of mild steel. Increasing concentrations of inhibitors contributed to high inhibition efficiencies, which were attributed to the simple blocking action of the anodic and cathodic sites by adsorption of the inhibitors molecules onto the M-S surface. Their inhibition efficiencies can reach about 90.9 % and 91.5 % when the optimal concentration is 10-3M for the two inhibitors FR178 and FR179 respectively.On the other hand, as the temperature rises, the anticorrosion capability of both FR178 and FR179 diminishes slightly and attains 82 % and 84 % respectively at the temperature of 328 K.Potentiodynamique polarization (PDP) and electrochemical impedance spectroscopy (EIS) demonstrated that both inhibitors examined act as mixed-type inhibitors.Furthermore, X-ray diffraction (XRD) and scanning electron microscopy coupled to energy dispersive spectroscopy (SEM/EDS) measurements indicated the formation of a protective layer adsorbed on the mild steel surface. The density functional theory (DFT) and molecular dynamics (MD) simulations were carried out to examine the correlation between molecular and chemical reactivity. The obtained results were found to be consistent with the experimental findings.

A multi-step ion-exchange methodology was developed for the fabrication of Cu(LaTa2O7)(2) lamellar architectures capable of wastewater depollution. The (001) diffraction line of RbLaTa2O7 depended on the guest species hosted by the starting material. SEM and TEM images confirmed the well-preserved lamellar structure for all intercalated layered perovskites. The UV-Vis, XPS, and photocurrent spectroscopies proved that Cu intercalation induces a red-shift band gap compared to the perovskite host. Moreover, the UV-Vis spectroscopy elucidated the copper ions environment in the Cu-modified layered perovskites. H-2-TPR results confirmed that Cu species located on the surface are reduced at a lower temperature while those from the interlayer occur at higher temperature ranges. The photocatalytic degradation of phenol under simulated solar irradiation was used as a model reaction to assess the performances of the studied catalysts. Increased photocatalytic activity was observed for Cu-modified layered perovskites compared to RbLaTa2O7 pristine. This behavior resulted from the efficient separation of photogenerated charge carriers and light absorption induced by copper spacer insertion.

Two novel fluorescent mesoporous silica-based hybrid materials were obtained through the covalent grafting of [4-hydrazinyl-7-nitrobenz-[2,1,3-d]-oxadiazole (NBDH) and N-1-(7-nitrobenzo[c][1,2,5]-oxadiazol-4-yl) benzene-1,2-diamine (NBD-PD), respectively, inside the channels of mesoporous silica SBA-15. The presence of fluorescent organic compounds (nitrobenzofurazan derivatives) was confirmed by infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), thermal analysis (TG), and fluorescence spectroscopy. The nitrogen physisorption analysis showed that the nitrobenzofurazan derivatives were distributed uniformly on the internal surface of SBA-15, the immobilization process having a negligible effect on the structure of the support. Their antioxidant activity was studied by measuring the ability to reduce free radicals DPPH (free radical scavenging activity), in order to formulate potential applications of the materials obtained. Cytotoxicity of the newly synthesized materials, SBA-NBDH and SBA-NBD-PD, was evaluated on human B16 melanoma cells. The morphology of these cells, internalization and localization of the investigated materials in melanoma and fibroblast cells were examined through fluorescence imaging. The viability of B16 (3D) spheroids after treatment with SBA-NBDH and SBA-NBD-PD was evaluated using MTS assay. The results showed that both materials induced a selective antiproliferative effect, reducing to various degrees the viability of melanoma cells. The observed effect was enhanced with increasing concentration. SBA-NBD-PD exhibited a higher antitumor effect compared to SBA-NBDH starting with a concentration of 125 mu g/mL. In both cases, a significantly more pronounced antiproliferative effect on tumor cells compared to normal cells was observed. The viability of B16 spheroids dropped by 40% after treatment with SBA-NBDH and SBA-NBD-PD at 500 mu g/mL concentration, indicating a clear cytotoxic effect of the tested compounds. These results suggest that both newly synthesized biomaterials could be promising antitumor agents for applications in cancer therapy.