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Enhancement of the Biological Potential of Herbal Extracts through Fermentation, Microwave-Assisted Extraction, and Iodine Catalysis
No full textIntroduction: The biological potential of herbal extracts can be significantly enhanced through fermentation, followed by microwave-assisted extraction (MAE). The selection of microorganisms capable of producing enzymes such as hemicellulase, cellulase, tannase, and glucosidase facilitates the release of polyphenols from the plant matrix, the depolymerization of tannins, and the conversion of glycosides into aglycones. This enzymatic activity results in fermented extracts with superior biological properties compared to non-fermented counterparts. Moreover, the addition of iodine during MAE, as a catalyst, enables the production of extracts with enhanced biological activity. The catalytic properties of iodine arise from its ability to form intermolecular bonds with electron-rich atoms within various functional groups, thereby facilitating nucleophilic reactions and enabling the synthesis of new compounds. Experimental: In this study, Achillea millefolium (yarrow) was fermented using two microorganisms: Lacticaseibacillus rhamnosus A71 and Saccharomyces boulardii. After fermentation, MAE was performed. A non-fermented control sample was prepared under the same conditions without the addition of microorganisms. For the iodine treatment, a second set of samples was prepared by adding iodine at a concentration of 1% (w/w) during the MAE process, while a control sample was extracted without iodine under identical conditions. The extracts were analyzed for polyphenol content, antioxidant activity (measured by ferric reducing antioxidant power and DPPH radical scavenging assay), antimicrobial properties (minimum inhibitory concentration, MIC, against pathogenic microorganisms), and acetylcholinesterase (AChE) inhibition. Results: Fermentation with L. rhamnosus A71 and S. boulardii led to a significant increase in polyphenol content in extracts, from 231 mg GAE/g to 332 mg GAE/g and 289 mg GAE/g, respectively. Antioxidant activity, expressed as ferric reducing antioxidant power, increased from 2.00 mmol Fe2+/g to 2.85 mmol Fe2+/g and 2.16 mmol Fe2+/g, while the IC50 values for DPPH radical scavenging decreased from 6.76 μg/mL to 6.23 μg/mL and 6.52 μg/mL, following fermentation with L. rhamnosus A71 and S. boulardii, respectively, indicating enhanced antioxidant potential. Antimicrobial activity was notably improved, particularly against Staphylococcus aureus, where the MIC decreased 16-fold (from 5 mg/mL to 0.32 mg/mL) for both fermented extracts, and against Pseudomonas aeruginosa, with an 8-fold reduction in MIC (from 2.5 mg/mL to 0.32 mg/mL) for the S. boulardii fermented extract. AChE inhibition increased from 31.7% to 42.6% and 43.1%, following fermentation with L. rhamnosus A71 and S. boulardii, respectively. When iodine was incorporated during MAE, the MIC against S. aureus decreased 2-fold compared to the extract without iodine. Antioxidant activity further improved, with ferric reducing antioxidant power increasing from 5.1 mmol Fe2+/g to 5.4 mmol Fe2+/g and the IC50 value for DPPH radicals decreasing from 6.96 μg/mL to 3.97 μg/mL. These findings demonstrate that fermentation with selected microorganisms followed by MAE and the addition of iodine during MAE enhance the bioactivity of herbal extracts, offering a promising strategy for developing functional plant-based products.International Conference "Biobased Future: Green Bioprocessing for Innovative Bioactive Products" ; June 16-18, 2025; Belgrade
Contactless Pulse Rate Assessment: Results and Insights for Application in Driving Simulators
No full textRemote photoplethysmography (rPPG) offers a promising solution for non-contact driver monitoring by detecting subtle blood flow-induced facial color changes from video. However, motion artifacts in dynamic driving environments remain key challenges. This study presents an rPPG framework that combines signal processing techniques before and after applying Eulerian Video Magnification (EVM) for pulse rate (PR) estimation in driving simulators. While not novel, the approach offers insights into the efficiency of the EVM method and its time complexity. We compare results of the proposed rPPG approach against reference Empatica E4 data and also compare it with existing achievements from the literature. Additionally, the possible bias of the Empatica E4 is further assessed using an independent dataset with both the Empatica E4 and the Faros 360 measurements. EVM slightly improves PR estimation, reducing the mean absolute error (MAE) from 6.48 bpm to 5.04 bpm (the lowest MAE (~2 bpm) was achieved under strict conditions) with an additional time required for EVM of about 20 s for 30 s sequence. Furthermore, statistically significant differences are identified between younger and older drivers in both reference and rPPG data. Our findings demonstrate the feasibility of using rPPG-based PR monitoring, encouraging further research in driving simulations
Parallel long-term radon level measurements by active and passive methods
No full textU ovom radu su prikazani rezultati istovremenih merenja koncentracije radona aktivnim Airthings radon detektorima, ugljenim kanistrima i CR39 trag detektorima, tokom 2024. godine. Merenja su rađena u četriri odabrane prostorije Visoke tehničke škole strukovnih studija u Zrenjaninu. Za poređenje rezultata merenja korišćen je ζ–test, čije su vrednosti pokazale dobra slaganja, uz napomenu da su merenja rađena na vrlo niskim koncentracijama (do 100 Bq/m3 ), gde su i procene merne nesigurnosti primenjenih metoda bile i preko 100 %.This paper presents the results of simultaneous annual measurements of radon concentration by Airthings radon detectors, charcoal canisters and CR39 track detectors, during 2024. Measurements are performed in four selected rooms at Technical College of Applied Studies in Zrenjanin. Obtained results are discussed. The ζ-test was used to compare the measurement results, which values showed a good agreement, but at very low concentrations (up to 100 Bq/m3 ), where the measurement uncertainty estimates of the applied methods were up to 100 %.XXXIII симпозијум ДЗЗСЦГ [Друштва за заштиту од зрачења Србије и Црне Горе] : 1-3. октобар 2025. године
Addressing processing limitations in SiC-based ceramic composites: A review of hybrid approaches and perspectives
No full textThis review presents an up-to-date overview of hybrid processing techniques for silicon carbide (SiC) matrix composites. These materials are widely used in systems where high temperatures, mechanical stress, and oxidation are serious concerns, such as in aerospace and energy applications. Although there are well-established fabrication methods for SiC composites, such as chemical vapor infiltration (CVI), polymer infiltration and pyrolysis (PIP), and reactive melt infiltration (RMI), each has its limitations. For example, while PIP is relatively simple, it often results in residual porosity. Additionally, CVI can yield high-quality microstructures, but it is a slow process and may still leave behind microporosity. Furthermore, RMI can deliver high densities, but may also cause fiber damage or leave behind residual silicon. Given the individual limitations of CVI, PIP, and RMI, hybrid approaches may be deployed to gain the benefits of multiple techniques. Most commonly, CVI and PIP are combined for hybrid processing, but other combinations of CVI, PIP, and RMI are possible. This review discusses how these combined processes are applied to various SiC-matrix composites, including carbon fibers in SiC matrix (Cf/SiC), carbon fibers in a matrix of C and SiC (Cf/C-SiC), and SiC fibers in SiC matrix (SiCf/SiC). The main contribution of this review is summarizing how hybrid techniques influence porosity, microstructure, fiber-matrix bonding, and the overall thermal-mechanical properties. Many recent studies are also included in the topics of improved fiber architectures, polymer chemistries, and infiltration steps. While hybrid methods often lead to improved properties, there are still open questions, especially regarding internal oxygen from PIP, long processing times for CVI, and phase stability after many cycles at high temperatures. This review concludes with potential future directions for research efforts to make hybrid SiC-matrix processes more effective, scalable, and reliable
The metamorphoses of the light cones of a relativistic particle on a ring
No full textIn this paper, we investigate the dynamics of a relativistic particle confined to a ring. The focus is on the metamorphoses of the functional form of the particle propagator induced by a change in the asymptotic parameter, proportional to the ratio of the ring length to the particle Compton wavelength. Tackling the divergent nature of the propagator enabled us to describe and classify all patterns produced by particle self-interference, regardless of the shape of the initial wave packet. We shall show under which conditions a quasiperiodic structure, known as quantum carpets, arises and demonstrate that its quartic part of the phase function, which structurally stabilizes the canonical carpet, is not just a correction but explains all features of the exact solution.This is the peer-reviewed version of the article: Ćosić, M., & Hadžijojić, M. (2025). The metamorphoses of the light cones of a relativistic particle on a ring. Chaos: An Interdisciplinary Journal of Nonlinear Science, 35(12). [https://doi.org/10.1063/5.0289963
Thermoresponsive hydrogels obtained by gamma radiation: Poly(alkylene glycol) methacrylates vs. poly(n-isopropylacrylamide)
No full textThis study offers a comparative analysis of two most important types of thermoresponsive hydrogels: poly(N-isopropylacrylamide) (PNiPAM) and poly(alkylene glycol) methacrylates (PAGMA). The latter includes poly(oligo(ethylene glycol) methacrylate) (POEGMA), a moderately hydrophilic polymer, and poly(oligo(propylene glycol) methacrylate) (POPGMA), its more hydrophobic counterpart. The hydrogels were produced using gamma irradiation in three different solvent systems: demineralized water, a water/ethanol mixture, and pure ethanol. Gel fraction measurements were used to assess the effects of monomer type, irradiation dose, and solvent composition on crosslinking efficiency. Swelling behavior was examined over a wide temperature range, highlighting distinct thermoresponsive features and volume phase transition temperatures (VPTTs). Differential scanning calorimetry (DSC) confirmed the presence of temperature-dependent phase transitions, while structural and chemical changes caused by radiation-induced crosslinking were analyzed using Fourier-transform infrared (FTIR) spectroscopy. Results showed that effective hydrogel formation is achievable at relatively low radiation doses. The choice of synthesis medium significantly influenced the formation and the gelation efficiency of hydrogels. Particularly, PNiPAM hydrogels were successfully synthesized without the use of alcohol and still demonstrated excellent swelling capacity and VPTTs near physiological temperatures, making them suitable for biomedical applications. These findings provide valuable insights for designing advanced smart hydrogels for biomedical and environmental uses
Evaluation of 161Tb-Labeled Diphosphonates as Potential Bone-Targeting Agents
No full textTwo diphosphonates, etidronic acid (HEDP) and zoledronic acid (ZOL), were radiolabelled
with 161Tb and evaluated as potential bone-targeting radiopharmaceuticals. Radiolabeling was performed at pH 7, achieving high radiolabeling yields (greater than 98%) and
demonstrating excellent in vitro stability in saline and human serum. Both radiolabeled
complexes exhibited hydrophilic behavior, a strong binding affinity to hydroxyapatite, and
moderate to high plasma protein binding. Biodistribution studies in healthy Wistar rats
demonstrated that 161Tb-HEDP and 161Tb-ZOL achieve high and stable skeletal uptake
with rapid blood clearance and minimal soft tissue accumulation. 161Tb-HEDP favored
higher initial bone localization, while 161Tb-ZOL showed lower renal and hepatic accumulation, indicating higher safety and selectivity. Compared to unchelated 161TbCl3, both
diphosphonate complexes exhibited significantly higher bone-to-kidney and bone-to-liver
ratios, resulting in superior targeting. Complementary experiments with non-radioactive
terbium were performed to investigate the redox behavior and confirm complex formation,
providing valuable insight into the stability and binding modes of the ligands. Both terbium and the ligands displayed well-defined redox behavior within the potential range of
−1 to 1.7 V, with complex formation evidenced by shifts in the oxidation peaks. Density
functional theory (DFT) calculations further supported these findings, showing that both
phosphonate groups of a ligand coordinate to Tb3+, while the hydroxyl groups in HEDP
enable intermolecular hydrogen bonding, contributing to additional structural stabilization.
Results encourage further investigations of 161Tb-labeled diphosphonates as promising
candidates for radionuclide therapy of bone metastases and other skeletal diseases
CQDs as antibacterial photoactive agents in polyurethane coating
No full textBacterial infections can easily spread over frequently touched surfaces like plastic, woоd and metal, due to the growth of bacterial biofilms. Antibacterial materials that we can put on critical surfaces can eliminate or inhibit the growth of bacteria. In this study, we produced photoactive polyurethane coatings on the basis of carbon quantum dots (CQDs). This material has showed antibacterial activity against gram-positive (Staphylococcus aureus, MRSA, Enterococcus faecalis) and gram-negative (Escherichia coli, Acinetobacter baumannii) bacteria after 1 h of exposure to blue light. CQDs were synthesized using one-pot solvothermal method. Nicotinamide was used as started precursor. Polyurethane composites on the basis of CQDs were obtained by swelling-encapsulating-shrinking process. Obtained CQDs and their composites were structurally, chemically and optically analyzed. AFM and TEM images of CQDs have showed core-shell structure with average diameter of 45,9 ± 1,5 nm. Homogeneous encapsulation has been demonstrated using confocal Raman mapping. Production of ROS was investigated using spectroscopic methods (UV/Vis, PL and EPR). Therefore, it is assumed that ¹O₂ and •OH have a synergistic effect to bacteria membranes, causing their damage and the death of bacteria. The good biocompatibility of the obtained composites was investigated by MTT and hemolytic assays and their effect was analyzed on the HaCaT cells and erythrocytes. These materials have potential application as antibacterial coatings in healthcare and other institutions where control of the spread of bacterial infections is needed.Twenty-Third Young Researchers' Conference Materials Science and Engineering, December 3-5, 2025, Belgrade, Serbia
Production and characterization of biochar and modified biochars by carbonization process of bearberry (Arctostaphylos uva-ursi. L.): Adsorption capacities and kinetic studies of Pb2+, Cd2+ and rhodamine B removal from aqueous solutions
No full textIn this work, Bearberry (Arctostaphylos uva-ursi L.) leaves and twigs were used as novel biomass source for production of biochar and modified biochars (manufacturing of microporous and mesoporous carbons by physical and chemical activations, using CO2 and H3PO4) via one-step carbonization (800 °C) with excellent physicochemical properties, for effective removal of Pb2+ and Cd2+ ions, and synthetic dye (Rhodamine B - RhB) from aqueous solutions. Results showed that carbonized (BL-C) and physically activated carbons (BL-CO2) as microporous adsorbents (specific surface areas 219.0 m2/g and 305.5 m2/g) show remarkable removal efficiency of Pb2+ (99.8 % and 99.9 %, for BL-C and BL-CO2), while these adsorbents showed moderate affinity for Cd2+ elimination (53.5 % and 48.5 %). BL-H3PO4 as mesoporous adsorbent with lower specific surface and larger pores (90.2 m2/g with Dmax = 33.6 nm), shows very good removal efficiency of PhB (~ 87 %). It was found that physical adsorption occurs during RhB removal onto BL-H3PO4, where dominant mechanism represents film diffusion, with reduced boundary layer effect. Adsorption process takes place over π–π, hydrogen bonding and electrostatic interactions. Adsorption processes of Pb2+ and Cd2+ onto BL-CO2 and BL-C take place via physical and chemical adsorption, but with different type of mechanism, including combination of diffusion and chemisorption (increased effect of boundary layer) and intra-particle diffusion (greatly reduced boundary layer effect), respectively. A very interesting fact found in this study, is that metal oxide surfaces (as Cu2O, SiO2, ZnO present in activated carbons) exhibit an efficient binding towards cadmium, providing physisorption capability onto non-metallic graphene features
Lignocellulolytic and plastolytic potential of groundwater and sediment bacteria from the serpentinization-driven hyperalkaline springs
No full textFour serpentinization-driven hyperalkaline springs (HAS) in the Jurassic ophiolites of western Serbia, with pH values between 11.1 and 11.7, were selected to assess the lignocellulose- and plastic-degrading potential of cultivable bacteria found in both the groundwaters and sediments of the zone of emergence of the investigated occurrences. Also, the physico-chemical properties of the groundwaters and petrological and mineralogical composition of sediments were examined. The HAS investigated are cold (temperature: 14.7–19.4 °C) and low in minerals (total dissolved solids: 104.1–450.4 mg/L) and belong to the Ca2+–OH− and Ca2+, Na+–OH− genetic type. Ca2+ was the most abundant cation (39.7–132.7 mg/L), followed by Na+ (2.0–82.5 mg/L) in three and Mg (6.6 mg/L) in one HAS, respectively. OH− was the most abundant anion (24.6–123.2 mg/L), followed by CO32− (18.0–36.2 mg/L) and Cl− (12.4–71.0 mg/L) in all tested groundwaters. Binocular examination revealed that gravelly spring sediments consist predominantly of peridotite, serpentinite, carbonate and quartzite clasts, while the powder X-ray diffraction experiments identified calcite and lizardite as the main mineral phases in the silt fraction. In total, 210 groundwater and sediment isolates were screened on lignocellulose and plastic substrates, and 33.8% of all screened HAS isolates (9.1% from groundwaters and 38.4% from sediments) degraded carboxymethyl cellulose. Selected bacterial isolates were identified by partial 16S ribosomal DNA sequencing to belong to the genera Bacillus, Peribacillus, Paenibacillus and Lysinibacillus; these could have potential applications in various commercial sectors requiring cellulose degradation. All identified isolates demonstrated growth on the plastic substrates Impranil® DLN-SD (SD) and Impranil® DL 2077 (DL), while three isolates, belonging to genera Bacillus, Peribacillus and Paenibacillus, respectively, demonstrated growth on all four tested plastic substrates (SD, DL, polycaprolactone diol and bis(2-hydroxyethyl) terephthalate). These isolates should be further explored as potential candidates for bioremediation treatments of plastic-polluted groundwaters and sediments.Data availability: Partial 16S sequences from selected cultivated HAS isolates are deposited in the GeneBank database (accession numbers PP190243-PP190254)