2025-12-24
Ayşegül Gümüş, Veysi Okumuş, Mustafa Emrullahoğlu, Selçuk Gümüş
Considering the extremely valuable biological and pharmaceutical properties of quinolines, novel water-soluble quinoline-based conjugates were designed and synthesized. In vitro antioxidant activities, such as free radical scavenging, metal chelating, and reducing-power activities, of the newly synthesized compounds ( WQ-1 , WQ-2 , WQ-3 , WQ-4 , and WQ-5 ) were determined. Although the highest scavenging activity (41.21 ± 1.18%) and chelating activity (23.53 ± 0.97%) at a concentration of 500.0 µg/ml were observed in WQ-4 , it was determined that WQ-5 had the highest reducing-power ability (0.417 ± 0.0116). The synthesized compounds were also tested for their antimicrobial activities against two Gram-positive and two Gram-negative bacteria, and it was determined that only WQ-3 showed low activity against Enterococcus hirae and Staphylococcus aureus . DNA-binding activities of the compounds were also studied using calf thymus DNA (CT-DNA). Additionally, the three-dimensional geometries and some electronic properties of the synthesized compounds were investigated with the density functional theory approach at B3LYP/6-31++G(d,p) level of theory.
2025-12-24
Marija Proševa, Andrea Petanova, Radmila Tomovska, Jadranka Blaževska Gilev
Improving the sustainability of polymer composites is a pressing priority, particularly in reducing reliance on fossil-derived components and minimizing environmental impact during synthesis. Lignin, an abundant and renewable natural polymer, offers significant potential as a bio-based additive due to its aromatic structure and intrinsic functionality. Conventional methods for incorporating lignin into polymer matrices often rely on non-sustainable, solvent-based routes, leading to poor dispersion and aggregate formation due to lignin’s incompatibility with polymers. This study presents a more sustainable approach using waterborne, in-situ semicontinuous miniemulsion polymerization to integrate lignin (0.5–1 wt%) into (meth)acrylic matrices. The resulting composite films, formed via water evaporation, exhibited enhanced UV and visible light absorption, improved mechanical strength, particularly at 1 wt% lignin and increased thermal stability even at low loadings. Despite lignin’s hydrophilicity, the composites demonstrated reduced water permeability. UV degradation studies showed that lignin’s chromophoric groups generate free radicals under UV exposure, triggering controlled photodegradation of both lignin and polymer phases. This controlled breakdown combined with the composite’s enhanced structural integrity highlights lignin’s dual function: reinforcing the material under standard conditions while enabling degradation under specific environmental stimuli.
2025-12-24
Rubin Gulaboski, Valentin Mirčeski
Cyclic voltammetry is considered as one of the most important techniques in electrochemistry, widely applied to investigate mainly mechanistic aspects, but also kinetics and thermodynamics of various redox processes. Many biochemical transformations in living systems involve electron transfer steps coupled with preceding, follow-up or regenerative chemical reactions, commonly assigned in electrochemistry as CE, EC, and EC′ mechanisms, respectively. Accurately simulating such processes is essential for understanding their behavior and for interpreting experimental voltammetric data. Despite extensive theoretical works available in the literature, freely accessible computational tools for simulating these mechanisms are scarce, thus limiting their use in both teaching and research contexts. This work introduces a set of ready-to-use simulation files developed in software package MATHCAD, designed to model cyclic staircase voltammograms for diffusional CE, EC, and EC′ mechanisms under the Butler-Volmer kinetic formalism. The protocols provided define and explain all relevant physical constants, potential waveform parameters, and dimensionless kinetic and thermodynamic variables required to define recurrent formulas for currents calculation. The approach also highlights the diagnostic value of analyzing relevant features of cyclic voltammograms to recognize particular mechanism from simulated voltammetric patterns. By making these simulation files freely available, the platform offers students and all electrochemists an interactive and intuitive learning tool, while providing experienced scientists with a useful theoretical platform for their experiments. This mainly educational work brings theoretical electrochemistry closer to all electrochemists, while enabling better mechanistic understanding of some of the most important electrode processes.
2025-12-24
Aleksandra Ivanoska-Dacikj, Gordana Bogoeva-Gaceva, Petre Makreski, Maja Ristova Delipetrev, Blažo Boev, Gligor Jovanovski
In this study, electrospinning was successfully employed to fabricate membranes based on polylactic acid (PLA), a polymer known for its biodegradability, containing varying amounts of opalized tuff (0, 2, 5, and 10 wt%). The addition of tuff introduced active mineral sites within the fibrous network, while the PLA matrix ensured mechanical stability, environmental sustainability, and prevention of secondary pollution. The electrospun membranes exhibited a uniform fibrous morphology with well-developed surface porosity, as confirmed by scanning electron microscopy. X-ray powder diffraction and Fourier-transform infrared spectroscopy verified the preservation of the characteristic structural features of both PLA and tuff, indicating successful incorporation of the filler without chemical alteration of the polymer matrix. Scanning electron microscopy combined with energy dispersive X-ray spectroscopy analysis demonstrated effective adsorption of nickel (Ni 2+ ) and lead (Pb 2+ ) ions from aqueous solutions, attributed to the high surface activity of the silicate mineral phase. These findings highlight the synergistic combination of a renewable, environmentally friendly polymer and a naturally occurring mineral filler to produce efficient and eco-friendly adsorptive membranes for heavy metal removal from aqueous solution.