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The Influence of Different Protocols on the Application of the Dithiothreitol Assay in Determining the Oxidative Potential of Ambient Particles
No full textEnvironmental particulate matter (PM) exposure has been widely recognized for its significant adverse effects on human health. Monitoring PM levels is one of the essential parameters of air quality assessment. However, PM mass concentration alone does not sufficiently explain its toxicological impacts and effects on health. This study highlights the importance of oxidative potential (OP) as a promising metric for evaluating PM toxicity. It focuses on standardizing the dithiothreitol (DTT) assay as a tool for OP measurement. In order to investigate the impact of various extraction techniques, reagent concentrations, and assay conditions, four previously established protocols were tested without modification, while a novel protocol was introduced based on an extensive literature review. Results revealed strong positive correlations between the new and most established protocols. These findings highlight the significance of the new protocol in advancing the development of standardized methodologies for applying the DTT assay and demonstrating its reliability and relevance. While developing a standardized DTT assay involves addressing numerous parameters—from filter extraction to assay application—this research provides a solid base for achieving consistency in OP measurements and overcoming this critical issue. © 2025 by the authors
Dual-energy computed tomography for non-destructive characterization of pigments in cultural heritage
No full textThe analysis of works of art (artifacts) requires non-destructive techniques that offer both morphological and material characterization. In this study, we show how Dual Energy Computed Tomography (DECT) could be used to characterize natural pigments (e.g., lead white, red lead, cinnabar, red ochre, etc.) in the painting layer of an18th-century icon. Image acquisition was performed on a clinical single-energy multi-slice CT scanner using four different X-ray tube potentials at 80, 100, 120, and 140 kV. Energy dispersive X-ray fluorescence (EDXRF) analysis was performed to validate material characterization results obtained from DECT. The optimal pair of X-ray tube potentials was found to be 80 and 120 kV, considering the maximum separation of the four regions of interest in two-dimensional Hounsfield units (HU) histogram space. Using lead white and cinnabar as a decomposition basis, maps of lead-based and mercury-based pigments were created from the dual energy (80 and 120 kV) CT scans using the material decomposition method. The obtained results were successfully validated against EDXRF measurements. The material maps were then used to analyse red pigments, i.e., distinguish red ochre and cinnabar pigments and exclude the presence of red lead from selected regions within the icon. The examination of the icon showed the new potential of the presented technique to provide valuable material composition information for the conservation and preservation study of artifacts while maintaining their integrity. © 2025 Elsevier Masson SA
On the geometry of Hamiltonian flow in 2D
No full textIn this paper, we investigate the geometry of the Jacobean tensor field generated by Hamiltonian flow in Hénon–Heiles potential. For this purpose, we have developed a new method for calculating the Jacobian tensor field based on the Caley transformation, particularly suited for studying 2D problems. To enhance its visualization, the Rotation-Diagonal-Rotation decomposition of the matrices was introduced, derived by imposing the continuity of Jacobian’s singular value decomposition. When the initial manifold is two-dimensional (all trajectories have zero initial momentum), each Jacobian’s symplectic block is represented as a 2D manifold embedded in the abstract 3D space, whose points are parameterized by two rotation angles and subdominant signed singular value (i.e. local characteristic Lapunov’s multiplier), obtained from the Rotation-Diagonal-Rotation decomposition, and colored according the value of the dominant signed singular value. It will be shown that each symplectic manifold consists of two sheets whose rotation angles differ by the value of . The evolution of the zero-level lines of the subdominant signed Lapunov’s multiplier explains the evolution and metamorphoses of the system’s caustic surfaces. There are always four local extrema of the subdominant multiplier corresponding to the maximal values of the dominant Lyapunov’s multiplier (which is almost always greater than one), thus identifying regions of the initial manifold particularly affected by the system’s chaotic dynamics
Estimated seasonal patterns of PM2.5 concentrations in Novi Sad using previously developed LUR models for winter and summer
No full textFor the first time in Serbia, two Land Use Regression (LUR) models were developed to estimate seasonal PM2.5 concentrations during winter and summer, specifically for Novi Sad. Based on these models, two prediction maps were generated to map and visualize the distribution of estimated seasonal variation of PM2.5 during heating and non-heating season on unsampled locations in Novi Sad. The estimation efficiency of winter and summer models was 55% and 40.3%, using two explanatory variables: total road length within a 50 m buffer (for both models) and total suburban area within a 3.000 m buffer (winter model). According to predictive map for winter, higher PM2.5 concentrations are observed around Novi Sad's urban core and suburban areas, where a significant portion of the population resides in residential houses and buildings. The estimated seasonal PM2.5 concentrations in Novi Sad ranged from 26.37 to 65.09 μg/m³. The lowest concentrations were found in the urban core, likely due to district heating, in contrast to suburban areas with mixed heating systems. Traffic intensity, as reflected by the 50 m road buffer, caused noticeable fluctuations, particularly in the areas like Klisa, Sajlovo, Shaingai and parts of Petrovaradin and Alibegovac. In summer, PM2.5 concentrations ranged from 12.43 to 16.09 μg/m³, with traffic patterns influencing concentrations, especially in the areas like Detelinara, Telep, and Petrovaradin. The predictors used as proxies for traffic intensity and domestic heating areas provided a solid foundation for developing relevant PM2.5 prediction surfaces19th International Conference on Chemistry and the Environment - Environmental Chemistry for Sustainability : Belgrade, Serbia, June 8-12, 2025
Evaluation of the lipophilicity of morpholino propiophenones by reversed-phase thin-layer chromatography and computational methods
No full textLipophilicity is considered one of the most critical physicochemical properties as it significantly impacts the biological activity and pharmacokinetics of drug molecules. It can be determined by experimental methods as well as by computational methods on the basis of the application of different software packages. In this paper, the retention behavior of 17 synthesized morpholino propiophenone derivatives in four reversed-phase thin-layer chromatography (RP-TLC) systems (tetrahydrofuran‒water, acetonitrile‒water, ethanol‒water, and acetone‒water) is presented, and the chromatography parameters RM0, S and C0 were determined. The most suitable RP-TLC system (acetone‒water) and chromatography parameter (RM0) for the lipophilicity prediction of the tested compounds was selected on the basis of the highest correlations with the calculated logP values. In this system, compounds 11 and 16 (derivatives with –OH as substituent in ring B) had the lowest, while compounds 4, 6, and 7 (with two halogen substituents) had the highest values of RM0. Quantitative structure‒retention relationship (QSRR) analysis was performed, and six models (OLS1(RM0), OLS2(RM0), PLS1(RM0), PLS2(RM0), SVM1(RM0), and SVM2(RM0)) were created to represent the relationships between RM0 and selected molecular descriptors. The molecular descriptors that form five most reliable models (ALOGP2, CATS2D_07_AL, Am, CATS2D_02_AL, RDF110m, DISPm, and CATS3D_03_LL) prove the existence of the relationship between lipophilicity and retention behavior in the selected RP-TLC system and indicate the importance of the selection of substituents in ring B. © Akadémiai Kiadó Zrt 2025
Sensor Fusion in Luminescence Thermometry: A Path to Higher Precision and Broader Applicability
No full textAdvancing measurement precision and extending the temperature range are key goals in luminescence thermometry. Traditional single-parameter methods often underperform. Sensor fusion (SF), a statistical tool widely used in fields like autonomous vehicles and medical imaging, is applied to luminescent thermometry by combining multiple sensor probes or treating each temperature-dependent parameter as a separate sensor. This approach consistently enhances precision and extends the temperature range, with fused precision equaling the sum of individual precisions. SF using inverse variance weighting surpasses traditional linear regression models due to its adaptability, achieving maximum performance with any sensor material. It works with both time-resolved and steady-state readouts, using single or multiple excitation sources. Computer simulations and experiments validate this method. For Sm2+, combining lifetime and intensity ratio measurements significantly improves precision across the entire range. Fusion of Mn4+, Ho3+, and Cr3+ lifetimes expands the temperature range to 300–650 K. For Yb3+/Er3+ upconversion green and red emission lifetimes, precision improves across all temperatures. However, Mn5+ shows limited improvement due to the dominance of precision in line-shift measurements, highlighting a limitation of the approach. Overall, SF demonstrates its potential to revolutionize luminescence thermometry by enhancing precision and usability across diverse conditions. © 2025 Wiley-VCH GmbH
Electrodeposited Co Crystalline Islands Shelled with Facile Spontaneously Deposited Pt for Improved Oxygen Reduction
No full textThe cobalt crystalline islands (Cocryst) were electrochemically deposited onto a glassy carbon (GC) support and then modified by a facile spontaneous deposition of platinum. The electrocatalytic activity of the resulting Cocryst-Pt core-shell catalyst was evaluated for the oxygen reduction reaction (ORR) in an alkaline medium. The XRD characterization of the Cocryst-Pt islands revealed that the cobalt core had a hexagonal close-packed (hcp) crystalline structure, and that the platinum shell exhibited a crystalline structure with a preferential (111) orientation. SEM images showed that the average lateral size of the Cocryst islands was 1.17 μm, which increased to 1.32 μm after adding platinum. The XPS analysis indicated that the outer layer of the bulk metallic Cocryst islands was fully oxidized. During the spontaneous deposition of platinum, the outer Co(OH)2 layer was dissolved, leaving the cobalt core in a metallic state, while the platinum shell remained only partially oxidized. The high electrochemically active surface area of the Cocryst-Pt/GC electrode, along with a suitable crystalline structure of the Cocryst-Pt islands, contributes to enhancing its ORR activity by providing a greater number of surface active sites for oxygen adsorption and subsequent reduction. The ORR on the Cocryst-Pt catalyst occurs via a four-electron reaction pathway, with onset and half-wave potentials of 1.07 V and 0.87 V, respectively, which exceed those of polycrystalline platinum and a commercial benchmark Pt/C
Poly(Methyl Methacrylate)-Based Core-Shell Electrospun Fibers: Structural and Morphological Analysis
No full textDicyclopentadiene (DCPD)–poly(methyl methacrylate) (PMMA) core–shell fibers were fabricated via coaxial electrospinning to develop a self-healing polymer composite. A PMMA shell containing a first-generation Grubbs catalyst was co-spun with a DCPD core at 0.5 mL h−1 and 28 kV, yielding smooth, cylindrical fibers. The diameter range of nanofibers was 300–900 nm, with 95% below 800 nm, as confirmed by FESEM image analysis. FTIR spectroscopy monitored shell integrity via the PMMA C=O stretch and core polymerization via the trans-C=C bands. The high presence of the 970 cm−1 band in the healed nanofiber mat and the minor appearance in the uncut core–shell mat demonstrated successful DCPD polymerization mostly where the intended damage was. The optical clarity of PMMA enabled the direct monitoring of healing progress via optical microscopy. The presented findings demonstrate that PMMA can retain a liquid active core and catalyst to form a polymer layer on a damaged site and could be used as a model material for other self-healing systems that require healing monitoring. © 2025 by the authors
Alkyl chain-dependent modulation of blood-brain barrier permeability in N-aryl-tetrahydroisoquinolines
No full textAlzheimer disease (AD) is an irreversible progressive neurodegenerative disease that causes failure of cerebral neurons and disability of the affected person to practice normal daily life activities. Despite extensive research efforts, no effective drug capable of significantly slowing or halting neurodegenerative processes has been developed. One of the main challenges in AD drug development is ensuring that therapeutic compounds can efficiently cross the blood-brain barrier (BBB) and reach adequate concentrations in the central nervous system (CNS). This ability is largely influenced by a molecule’s lipophilicity and its ADME (absorption, distribution, metabolism, and elimination) properties. Additionally, over the years, numerous studies have shown the importance of lipophilicity in individual ADME parameters, highlighting its importance in drug design. Identifying the optimal range of lipophilicity has become a strategy in the optimization of lead compounds. This study deal with experimentally and theoretical evaluation of the impact alkyl chains at the R1 position of N-Aryl-tetrahydroisoquinolines on BBB permeability of these compounds. For theoretical evaluation the ADME properties of three N-aryl- tetrahydroisoquinoline (THIQ) derivatives, each differing in the alkyl-substituted ketone at the R1 position were examined using the SwissADME tool, alongside experimental assessments of their lipophilicity and BBB penetration ability. SwissADME predictions indicated that all three compounds (1a, 1b, and 1c) had the potential to penetrate the BBB. However, according to Lipinski’s Rule of Five, compounds 1b and 1c did not meet drug-likeness criteria due to their elevated logP values, suggesting higher lipophilicity. To experimentally validate these predictions, logP values were determined using the ultra-performance liquid chromatography (UPLC) method. The results confirmed that the measured logP values were within the range typically suitable for drugs targeting neurodegenerative diseases, in accordance with Lipinski’s guidelines. Furthermore, it was observed that lipophilicity increased as the alkyl chain length extended. To further investigate the BBB permeability of the synthesized compounds, a Parallel Artificial Membrane Permeability Assay for the BBB (PAMPA-BBB) was carried out. The results revealed that despite all three compounds possessing logP values within an acceptable range for AD drug candidates, only compound 1a successfully permeated the artificial BBB model. In contrast, compounds 1b and 1c, despite having comparable logP values, exhibited high lipophilicity, which prevented their detection in the assay. These findings confirm the importance of optimizing lipophilicity and that compound 1a could be potential candidate for drugs in AD disease.13th International Conference on Radiation, Natural Sciences, Medicine, Engineering, Technology and Ecology - RAD 2025; 16-20 June 2025, Herceg Novi, Montenegro
Microstructural, chemical and photocatalytic properties of strontium gadolinium oxide doped with Tm3+ and Yb3+ ions
No full textThis is the first report of photocatalytic degradation employing SrGd2O4 nanoparticles doped with Tm3+ and Yb3+ ions. The sample was prepared via the sol-gel assisted combustion method using concentrations of 1 at% Tm3+ and 4 at% Yb3+. An X-ray Diffraction (XRD) investigation showed that all diffraction peaks are allocated to a pure orthorhombic phase. Transmission and Scanning Electron Microscopy (TEM, SEM) revealed the existence of porous agglomerated round-shaped particles, arranged in network-like structures. Energy Dispersive X-ray Spectroscopy (EDS) verified the presence of all structural elements, as well as their uniform distribution across the particles. UV-VIS Diffuse Reflectance Spectroscopy (UV-VIS DRS) enabled determination of the band gap, which was calculated to be 4.3 eV. X-ray Photoelectron Spectroscopy (XPS) revealed the presence of OH− groups on the material surface. Photocatalytic properties were observed through the degradation of Methylene Blue. The results indicated that after 4 h of exposure to the simulating sun irradiation, about 50 % of the initial dye concentration was mineralized. © 2025 Elsevier B.V