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Adsorption of diclofenac and ibuprofen on organobentonites: Kinetic, thermodynamic, and simultaneous adsorption
No full textIn this study, bentonite clay was modified with a primary amine – dodecylamine and a quaternary ammonium salt – di(hydrogenated tallow)dimethylammonium chloride (Arquad® 2HT-75) to enhance its affinity for nonsteroidal anti-inflammatory drugs, specifically diclofenac sodium (DCF) and ibuprofen (IBU). The structural and surface properties of prepared organobentonites were characterized using XRPD, SEM, FTIR, zeta potential, and simultaneous thermal analysis techniques. Adsorption experiments revealed that organobentonites exhibited significantly higher capacities for DCF and IBU compared to natural bentonite, with adsorption kinetics following a pseudo-second-order model and isotherms fit the Langmuir model. Thermodynamic analysis indicated spontaneous and exothermic adsorption at all temperatures. Additionally, simultaneous adsorption experiments provided insight into the competitive interactions between DCF and IBU, showing that despite a decrease in adsorption performance, both drugs could be effectively removed by the modified bentonites. Post-adsorption characterization confirmed drug adsorption within the organobentonites structure, highlighting the potential of these materials for wastewater treatment
FeCo flower–like nanoparticles embedded in PVDF–HFP fibers as efficient magnetoelectric composite
No full textIn this study, novel magnetoelectric (ME) composites consisting of flower-like FeCo nanoparticles embedded in PVDF-HFP fibers and films were fabricated via electrospinning and solution casting. Samples containing 0.1, 7, and 22 wt% FeCo were examined to elucidate how nanoparticle loading, morphology, and architecture affect structure, magnetic properties, ferroelectricity, and ME performance. The composites were characterized by TEM, SEM, XRD, FTIR, Mössbauer spectroscopy, SQUID magnetometry, ferroelectric testing, and ME coupling coefficient measurements. Electrospun PVDF-HFP fibers exhibited a strong structural α→β transformation, reaching high electroactive β-phase fractions, while cast films predominantly formed the γ-phase. The flower-like FeCo morphology increased surface-to-volume ratio and facilitated efficient strain transfer at the polymer–particle interface. Post–processing through cold and hot pressing enhanced the mechanical strength of the composites and improved interfacial phase bonding, leading to strong magnetoelectric coupling under low magnetic fields. Under AC magnetic excitation of 2–12.5 Oe at 30 kHz, all samples demonstrated ME voltage response. The highest ME coefficient, αME≈450mV/cmOe, was obtained for cold-pressed electrospun fibers with 0.1 wt% FeCo, correlating directly with high β-phase content (≈93.7 %) and uniform nanoparticle dispersion. A clear dependence of ME output on phase composition, particle distribution, and processing parameters was established. Comparison of 0–1 (fiber) and 0–3 (film) architectures using identical constituent materials revealed superior ME performance in the fiber-based composites. These findings highlight the potential of nanostructured PVDF-HFP/FeCo composites for low-field magnetoelectric sensing, energy-efficient multifunctional devices, and flexible electronics, while providing new quantitative insight into coupling mechanisms in soft-magnetic nanoparticle–polymer systems
Light-Driven Riboflavin loaded Au/TiO₂ micromotors as a Promising Strategy for Targeted Melanoma Therapy
No full textLight-driven metal-oxide micromotors have emerged as promising theranostic tools for efficient tumor penetration and intracellular drug delivery, enabling more precise targeting and enhanced treatment of malignant cells [1,2]. Titanium oxide (TiO₂) micromotors can overcome tumor microenvironmental barriers under light irradiation and propel themselves using tumor-derived H₂O₂ [3]. This self-propulsion enhances cellular uptake and therapeutic efficacy, although the exact mechanisms underlying their antitumor activity remain incompletely understood [4]. In this study, we characterized the physicochemical properties and investigated the biological effects of newly developed riboflavin (vitamin B2)-loaded gold–titanium dioxide (Au/TiO₂-RbF) micromotors in human A375 melanoma cells in vitro. Structural analysis by SEM revealed that the Au/TiO₂ particles were spherical, uniform, and well dispersed, with an average diameter of approximately 1 µm, consistent with DLS measurements. Elemental mapping using HRTEM/EDS confirmed a homogeneous distribution of Au, Ti, and O throughout the particles. UV–vis spectroscopy of the Au/TiO₂ micromotors showed strong absorption in the UV region (200–400 nm), characteristic of TiO₂, along with an additional peak at 550 nm corresponding to Au. Photoluminescence excitation analysis demonstrated stable and intense UV fluorescence with a maximum emission at 360 nm upon 280 nm excitation, accompanied by visible emission originating from RbF in the 500–600 nm range. Importantly, riboflavin acts as an efficient photosensitizer, and its activation under UVA irradiation leads to enhanced reactive oxygen species (ROS) generation. Using EPR spectroscopy, we demonstrated significantly increased singlet oxygen production from Au/TiO₂-RbF micromotors upon UVA exposure, confirming the photoactivated ROSgenerating capability of the system. To evaluate the biological effects, MTT assays revealed no significant cytotoxicity of the micromotors (5–20 µg/mL) in non-irradiated A375 human melanoma cells after 24 h of treatment. In contrast, UVA irradiation for 2 h triggered dose-dependent cytotoxicity in micromotor-treated cells. Phase-contrast microscopy further revealed morphological changes consistent with apoptotic cell death. Collectively, these results demonstrate that RbF-loaded Au/TiO₂ micromotors induce UVA-triggered, ROS-mediated apoptosis in A375 melanoma cells while exhibiting minimal toxicity in the absence of irradiation. Taken together, our findings highlight the potential of Au/TiO₂-RbF micromotors as a safe and effective light-activated platform for targeted anti-melanoma therapy.19th Photonics Workshop, (International Conference), Kopaonik, March 08-12, 2026
Gamma rays assisted synthesis of N doped-graphene quantum dots from multiwall carbon nanotubes
No full textGamma rays are the powerful tool for top-down synthesis of nitrogen doped graphene quantum dots (NGQDs) from multiwall carbon nanotubes. Different doses of gamma rays (100, 200 and 300 kGy) were applied to the multiwall carbon nanotubes suspended in mixture of sulfuric and nitric acid (3:1 ratio). After purification, NGQD were characterized to investigate their structure (morphology, particle size, nanomechanical and nanoelectrical properties, chemical composition, photoluminescence, reactive oxygen species production, antibacterial activity and biocompatibility). Viscoelastic measurements revealed that NGQDs nanoparticles had Young’ modulus of elasticity almost equal to single wall carbon nanotubes (SWCNTs (6,5)). Electrostatic force and scanning tunneling microscopy showed that all types of the NGQDs nanoparticles had negative charge distributed homogeneously. All NGQDs samples produced singlet oxygen and the NGQDs300 sample showed moderate antibacterial activity and good biocompatibility
Structural exploration of holmium fluoride selenide (HoFSe): theory and experiment
No full textRare-earth metal (RE), and in particular holmium (Ho) based materials have received considerable attention due to their scientific and industrial applications. While rare-earth metal fluorides and rare-earth metal selenides have been studied for a long time for various applications, as well as their very interesting electronic properties, optical properties, and superconductivity, Holmium selenides and holmium fluoride selenides have only been recently investigated. An exhaustive study of the holmium fluoride selenide (HoFSe) was performed using a multidisciplinary approach, providing fundamental research in this chemical system. Three polymorphs of HoFSe were synthesized through high-temperature experiments and characterized using single-crystal X-ray diffractometry (SCXRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) spectroscopy. Energy landscape exploration and crystal structure prediction (CSP) were performed using global optimization (GO) and data mining (DM) based searches, followed by local optimization using density functional theory (DFT), resulting in alternative crystal structures at non-equilibrium conditions as a function of pressure and temperature. We believe this study provides a unique perspective and complete picture of the structural features of HoFSe which will enable future investigations of properties and applications
Comment on "A comprehensive exploration of optical properties of GdAlO3:Cr3+"
No full textA recent study by Souissi et al., Opt. Mater., 162 (2025) 116841, assigns emission features between 680 nm and 720 nm and a broad excitation band at 324 nm to the Gd3+6PJ → 8S7/2 transitions. In this comment, we offer an alternative interpretation of these spectral features. The origin of these transitions is clarified by recording the excitation and emission spectra, along with decay profiles, for the optically active centers present in our pristine and Cr3+-doped GdAlO3 samples. Our investigation reveals that these spectral features originate from octahedral-site Mn4+ in GdAlO3. This reassignment is corroborated by previously reported spectroscopic data on Mn4+ in GdAlO3. The Mn4+ is likely introduced as trace impurities either from the Al2O3 precursor or introduced inadvertently during synthesis
Photoluminescence investigations of YPO4:Tb3+ nanoparticles and YPO4:Tb3+/PMMA luminescent nanocomposite films for potential energy applications
No full textIn this work, synthesis and characterizations of PMMA-based luminescent nanocomposite (LNC) films loaded with varying content of YPO₄:Tb³+(5 at.%) luminescent nanoparticles (LNPs) are reported along with detailed structural, morphological, and photoluminescence investigations. The YPO₄:Tb³+ LNPs, prepared via sol-gel, exhibited a pure tetragonal phase with high crystallinity as confirmed by X-ray diffraction studies. Electron microscopy analysis of LNPs revealed quasi-spherical NPs of 60 nm forming micrometer-scale agglomerates. Photoluminescence investigations of LNPs under near-UV excitation at 370 nm characterized by visible emission (at 450–650 nm) showed characteristic intraconfigurational transition of Tb3+ ions, dominated by strong green emission at 545 nm attributed to ⁵D₄ → 7F₅ transition. Furthermore, when these YPO₄: Tb³+(5 at.%) LNPs were embedded in PMMA, LNPs kept their luminescence properties in LNC film. The quenching phenomenon in LNC films was observed at mass ration mNPs/mPMMA=25wt.% due to energy transfer between LNPs. Additionally, temperature-dependent photoluminescence of LNC films revealed good thermal stability without quenching. This study has clearly identified the potential applications of YPO₄: Tb³+/PMMA based LNC films in energy conversion (photovoltaic conversion) and solid state lighting applications
Advanced GIS-Based RUSLE Modeling for Soil Erosion Estimation in the Toplica River Basin, Serbia
No full textAmong the most serious types of land degradation, soil erosion poses a major threat to agricultural productivity, water quality, and ecosystem stability. Using a multidisciplinary approach, this study aimed to identify the spatial patterns of soil erosion and dominant drivers influencing soil loss in the Toplica River Basin in southern Serbia. Soil properties, including texture and organic matter content, were analyzed in samples collected throughout the study area, accounting for variations in altitude, soil type, and land use, to determine the erodibility factor (K). The rainfall erosivity factor (R), topographic factor (LS), and cover management factor (C) were determined using available inputs on rainfall erosivity, topography, land use, and vegetation cover. The Revised Universal Soil Loss Equation (RUSLE) was used to estimate annual soil erosion rates, and GIS tools and cartographic techniques were used to create spatial layers for each RUSLE factor and to generate a detailed erosion risk map. The results showed a mean annual soil loss of 5.45 t ha−1 year−1, with values ranging from 0 to 397.09 t ha−1 year−1, indicating considerable spatial variability. The regression modeling revealed the dominant roles of factors LS (β = 0.828), C (β = 0.731), and their interaction (LS × C, β = 0.561), followed by rainfall-related interactions (R × C, β = 0.268 and R × LS, β = 0.261). Two dominant erosion regimes were distinguished: topography-controlled erosion in mountainous regions and land-use-controlled erosion in low- to moderately sloping agricultural areas. The maps and analyses presented in this study provide a process-based framework for interpreting spatial erosion patterns, identifying critical hotspots and areas with higher erosion risk, and supporting more focused and context-aware conservation strategies
Highly Photosensitive and Stable SiC/ZnO Nanowire Photoelectrochemical Ultraviolet Photodetector Based on Heterojunction Engineering for Reliable Complex Underwater Application
No full textThe precise tailoring of bandgap structures as well as carrier separation and transport behavior via heterojunction engineering can provide a practical and viable pathway for enhancing the performance of low-dimensional semiconductor devices. In this study, a highly photosensitive photoelectrochemical (PEC) ultraviolet (UV) photodetector (PD) based on a SiC/ZnO heterojunction is explored. The surfaces of SiC nanowires are successfully modified using high-quality ZnO nanospheres via a simple hydrothermal process. The as-constructed SiC/ZnO heterojunction nanowire PEC UV PD achieves high photodetection performance—high responsivity (15.76 mA W−1), high detectivity (1.827 × 1010 Jones), excellent external quantum efficiency (5.21%), and fast rise/decay times (186/454 ms), under 375-nm UV illumination. Remarkably, the device exhibits a high photoresponse under different solution concentrations, temperature conditions, and excellent aging stability over long-term operation. Its highly sensitive and reliable photodetection performance could be attributed primarily to the synergy among the type-II charge transfer pathways formed at the SiC/ZnO heterojunction, enhanced photogenerated-carrier separation efficiency, and improved light–matter interactions enabled by the large specific surface area of the ZnO nanospheres. Overall, this study establishes a paradigm for developing highly sensitive PEC PDs suitable for optical communication under harsh underwater conditions, thereby advancing heterojunction and interfacial engineering strategies for next-generation optoelectronics
Atto-localization in a one-dimensional lattice
No full textA simple tight-binding model with hopping to the nearest-neighbor sites in the field of attosecond pulse train is considered. A new form of localization, atto-localization, has been obtained. It is checked by simulating as realistically as possible the appropriate hopping in the lattice. This is a drastic change with respect to the Anderson localization. Examinations are performed on an ideal and a disordered lattice. Pair-correlations, density of states, inverse participation ratio and energy level statistics are calculated and verified. The condition under which atto-localization does not appear is also given.This is the peer-reviewed version of the article: Mašović, D. R. (2026). Atto-localization in a one-dimensional lattice. Canadian Journal of Physics, 104, 1-9. [http://dx.doi.org/10.1139/cjp-2025-0195