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Mechanical Properties of the Bio-Composites: Effect of Kraft Lignin and Flax Fabric to Camphoric Acid Based Unsaturated Polyester Resin's Reinforcement
No full textThe development of the technology for bio-based resin and related composites production has nowadays become a key focus in materials research. In line with that, in this study, the effect of the structure of camphoric acid (CfA) based unsaturated polyester resin (Cf-UPR) on the mechano-chemical properties of related Cf-UPR/KfL composites, produced at 5–20 wt.% of Kraft lignin (KfL) addition, was examined. Camphoric acid, along with bio-based maleic anhydride (MA) and propylene glycol (PG), was used in the synthesis of the Cf-UPR designed to enhance the wetting power of KfL providing improvement in mechanical properties and thermal stability of the composites. The structure of Cf-UPR was proved using FTIR and NMR techniques. The morphological and mechanical properties of Cf-UPR/KfL composites were studied using FE-SEM, TEM, TGA, DTA, micro indentation, and tensile test measurements. The tensile strength and toughness increase, compared to pure Cf-UPR, for 23.9% and 93.4% at 5 wt.% KfL addition in Cf-UPR, respectively, while at higher KfL addition the values gradually decrease. The maximum increase in microhardness, 33.1%, was recorded with the addition of the 5 wt.% KfL. Furthermore, the tensile strength of the flax fabric-reinforced laminated composite (Cf-UPR/Ff) increased by an impressive 481%, which corroborates the idea about future consideration of sustainable production of high-performance bio-based composites. By using renewable resources and minimizing environmental impact, this method not only improves the material's performance but also complies with green chemistry principles. These composites are suitable for use in construction materials, automobile parts, and other sectors looking for environmentally friendly substitutes
Performance estimation of a steam-turbine driven multistage compressor system
No full textThis work presents a deterministic model developed to estimate the real-time performance parameters of a compact device which uses a steam turbine to drive a multistage compressor system. The approach focuses on evaluating the thermal and mechanical efficiencies of individual system components, including steam turbines and multistage compressors under varying operating conditions, with particular attention to system-level energy efficiency and interdependencies. The model captures the interaction between the steam turbines and compressors, enabling an integrated analysis of energy transfer, shaft power consumption, and thermodynamic and mechanical losses across system. A case study was conducted on three steam-driven multistage compressor system (SDMSCS) units at a local ethylene plant: Case 1 (cracked gas), and Case 2 (propylene), Case 3 (ethylene), so as to demonstrate the effectiveness and versatility of the proposed method. The model was validated by comparing simulated results to actual energy consumption data, and design specifications were used as a reference point. The analysis estimated energy transfer per compressor stage, turbine-extracted energy, shaft power, polytropic efficiency, and mechanical efficiency. It was found that Case 2 exhibits the highest model accuracy with close alignment to design efficiencies across stages, while Case 1 resulted in significant underprediction and larger deviations, especially in later stages. As such, the method's effectiveness was demonstrated with model efficiencies closely matching design values within 2–10 % deviation for most stages, and highlighting areas for improvement where deviations reached up to 37 % in later stages
Poster: "Docking analysis and preliminary in vitro evaluation of various analogues for PET imaging of AMPAR"
No full textNeurodegeneration is a key pathological hallmark of disorders, such as Alzheimer’s disease and it is negatively correlated with synaptic plasticity. It is a complex interplay of various factors, including glutamatergic neurotransmission via α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPAR). Changes in the expression of AMPAR, can be quantified by positron emission tomography (PET). Thus, we aim to develop an improved PET radiotracer based on previously chemical scaffold of PEPA, for imaging AMPAR with PET, which can serve as a practical tool for assessing brain function.Poster presented at 20th European Molecular Image Meeting 2025, 11-14 March 2025, Bilbao, SpainAbstract: [https://cer.ihtm.bg.ac.rs/handle/123456789/8539
Mechanical performance of 3D-printed PLA after artificial aging
No full textThis study examines the mechanical performance of a 3D-printed PLA quadcopter arm fabricated with reduced infill density and subjected to artificial aging. The aging process simulated real-world environmental exposure through thermal cycling, humidity, UV/IR radiation, and freeze-thaw conditions. Tensile strength testing was conducted to assess mechanical integrity, while FTIR spectroscopy, colorimetric analysis, and wettability measurements were employed to evaluate material degradation. Despite a notable reduction in mechanical strength, the component maintained functional performance throughout the testing period. Numerical simulations further supported the experimental findings by identifying stress concentration zones and the onset of plastic deformation. Importantly, even after aging and with a low infill density of 30%, the potential of low-infill PLA components for use in lightweight and cost-effective drone applications, where both mechanical resilience and material efficiency are critical
Hydrocarbon signatures as a tool for unraveling the stratigraphic problem for Upper Cretaceous–Paleogene sediments from Internal Dinarides, Serbia
No full textInorganic and organic geochemical analyses, assisted by micropaleontological investigations, were performed on the Paskovac sediments to differentiate the Cretaceous and Paleogene deposits in Internal Dinarides region. Owning to the presence of fossil assemblages in the in Upper Cretaceous sediments and their scarcity in the Paleogene siliciclastic sediments, the entire Paskovac area was fundamentally incorrectly classified as the Campanian–Maastrichtian. Besides, the Paskovac sedimentary sequence was formed as a consequence of the uppermost Cretaceous–Paleogene tectonic shortening of the Dinarides, during which the Maastrichtian sediments were re-deposited within the Paleogene sequence from the underlying Maastrichtian sediments. Therefore, this study employed thin-section microscopy, atomic absorption spectrometry (AAS), and gas chromatography–mass spectrometry (GC–MS) techniques to closely inspect 27 samples from the Paskovac drillhole. The results revealed a clear division of the samples into two groups based on their geochemical similarities. One group marked as Paleogene clastic sediments characterizes the highest content of terrigenous elements, namely SiO2 (49.49 %–62.22 %), Al2O3 (16.18 %–21.75 %), Fe2O3 (3.41 %–6.67 %), TiO2 (0.63 %–0.80 %), along with sulfur content (2.33 %–2.80 %). The organic matter is rich in odd long-chain n-alkanes, C29 regular sterane (>60 %), benzohopanes, retene, cadalene, and benzo[b]naphthofurans, suggesting predominately terrestrial biomass deposited under suboxic–oxic conditions. Another group, represented by carbonates (CaO up to 51.02 %), contains Maastrichtian assemblages (e.g., Siderolites calcitrapoides), indicating shallow-marine depositional settings. Short-chain even n-alkanes, branched alkanes (e.g., 5,5-diethylalkanes), and C27 regular sterane suggest the presence of biodegraded mixed algal/microbial biomass
Pechini synthesis method of Ho2O3 nanoparticles and their harnessing for extremely sensitive electrochemical sensing of diuron in juice samples; theoretical insights into sensing principle
No full textThis study developed a new electrochemical sensor for diuron (DIU) detection using a carbon paste electrode (CPE) upgraded with Ho2O3 nanoparticles. The Pechini method was used to synthesize Ho2O3 nanoparticles. The nanostructure properties of the material were confirmed using X-ray powder diffraction (XRPD), attenuated total reflectance (ATR) - Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The material electrocatalytic features were investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). An analytical method for identifying and measuring DIU was established using square wave voltammetry (SWV). The proposed sensor exhibited a remarkable response to DIU, displaying a broad linear range (0.25 - 200 µM) and a detection limit of 0.03 µM. Its minimal influence from potential interfering substances confirmed the method's selectivity. When detecting DIU in water and juice samples, the CPE/Ho2O3 sensor showed good recovery results. The conventional UV–Vis detection method validated the sensor efficacy. © 2025Accepted version: [https://cer.ihtm.bg.ac.rs/handle/123456789/8697
Design of an Electrochemical Sensor for Glyphosate Detection Using Molecularly Imprinted Polymer Coating on MOF-Modified Glassy Carbon Electrode
No full textMolecularly imprinted polymers (MIPs) play a crucial role in artificial molecular recognition, as they are designed with cavities that precisely correspond to the target analytes. These polymers exhibit exceptional affinity and selectivity towards the desired analyte; however, their flexibility can lead to structure deformation, which ultimately reduces their effectiveness. The combination of MIPs with metal-organic frameworks (MOFs) due to their rigid structure has proven effective way to prevent such deformation. Additionally, the incorporation of MIP layers can enhance the stability of MOFs. The resulting MIP@MOF composite effectively combines the advantages of both materials while mitigating their respective drawbacks .
In this research, we have developed a novel electrochemical sensor for glyphosate (GLY) detection, utilizing a composite made of graphene oxide and Y-MOF for glassy carbon electrode (GCE) modification. This composite was synthesized using a hydrothermal method, and subsequently characterized using advanced techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). The incorporation of prepared material onto the surface of the GCE, results in a high electrode surface porosity which enhances the binding capacity of the MIP film. Prior this MIP polymerization process, quantum chemical calculations were used to understand the interaction between more than 20 functional monomers and GLY molecule, allowing selection of the optimal monomer for polymer synthesis with maximum selectivity toward selected analyte. Based on these calculations, o-phenylenediamine (oPD) was identified as the optimal monomer for further electropolymerization experiments. After optimizing the experimental conditions for the preparation of MIP@Go-Y-MOF/GCE, we advanced to the development of an analytical technique for the detection of GLY. Given that GLY molecules are non-reactive and occlude the cavities within the MIP film, all measurements were conducted in a solution containing the redox probe [Fe(CN)6]3−/4−, driven by differential pulse voltammetry. The re-adsorption of GLY within the MIP layer—following an incubation period in solutions with varying analyte concentrations—results in a decrease in the electrochemical intensity of the redox probe. The MIP sensor displayed a significant linear response to GLY concentrations ranging from 1 nM to 10 µM.
This work presents a promising method for developing electrochemical sensors that exhibit excellent performance in the quantitative determination of GLY. The effectiveness of this approach for detecting GLY in complex samples highlights its considerable potential in the domains of food safety
Impact of rainfall characteristics on sediment transport and runoff onset during simulated storm events
No full textThis study experimentally investigated the effects of rainfall intensity (I), drop diameter (dm50), kinetic energy (KE), and momentum (M) on sediment transport and runoff, using a rainfall simulator over three soil plots. Simulated rainfall conditions ranged from 1.40 to 4.60 mm/min (I), 0.90 to 1.90 mm (dm50), 0.60 to 2.30 J·m⁻²·min⁻¹ (KE), and 0.008 to 0.027 N·m⁻² (M). Twelve simulations were performed, each lasting 30 minutes, with samples taken at 5-minute intervals to monitor runoff and sediment yield dynamics. Surface runoff began around minute 15 in some cases, later in others, and was absent in half. Peak sediment concentration (Cpar) ranged from 0.8 to 11.0 g/L, sediment transport rate (Wpar) from 0.1 to 4.5 g·min⁻¹·m⁻², and runoff rate (Qpar) from 0.3 to 2.8 mm/min. Cumulative runoff volume (Qcum) ranged from 6.0 to 42.0 mm, and cumulative sediment yield (Wcum) from 0.1 to 25.0 g/m².
The analysis showed that variations in rainfall characteristics significantly influenced runoff timing, regime, and sediment yield. The hypothesis that rainfall effects differ between simulations with and without formed surface runoff was not supported. Initial correlations between Qpar, Wpar, and Cpar were weak (0,3–0,5) to moderate (0,5–0,7) becoming strong (0,7–0,9) after 10 minutes, similar to Qcum and Wcum. A strong (0,7–0,9) and consistent relationship between Wpar and Cpar persisted due to direct interaction and small plot size. Regression analysis confirmed progression from weak (0,3–0,5) to strong (0,7–0,9) dependencies.
While I, KE, and M dominated early erosion response, dm50 became most influential later. Combined rainfall factor interactions showed predictive strength across all simulation phases. For the 30-minute period and runoff onset time (tft), Qcum correlated strongly with dm50, KE, and M, and moderately with I. Wcum followed a similar pattern. These findings support data-driven assessment of rainfall-induced erosion and storm impact modeling
Advanced composite coatings on titanium with improved adhesion for use in medicine and dentistry
No full textThe long-term performance of titanium-based implants largely depends on their ability to achieve
strong interfacial bonding with surrounding tissue while maintaining structural stability under
physiological conditions. Although titanium exhibits excellent mechanical properties, corrosion
resistance, and biocompatibility, its inherently low bioactivity limits direct tissue integration. To
address this challenge, recent research has focused on developing advanced composite surface
coatings that combine inorganic bioactive phases with organic biopolymers to improve surface
functionality, adhesion, and biological response.
This study investigates composite coatings engineered through a combined electrochemical and
electrophoretic process designed to simultaneously modify the titanium surface and deposit a
multifunctional hybrid layer. The approach enables the formation of a titanium-oxide-based
intermediate structure that enhances coating adhesion, while the incorporated bioactive phases
provide favorable chemical and structural conditions for cellular attachment and growth. Structural
and chemical characterization techniques, including XRD, FTIR, SEM and adhesion testing, were
employed to evaluate crystallinity, functional groups, and surface morphology. Results confirmed the
successful formation of well-adhered composite layers with controlled microstructural features and
well-developed porosity, which is beneficial for subsequent biological interactions.
Adhesion testing revealed high coating integrity, exceeding the performance typically observed for
conventionally deposited ceramic layers. This improvement is attributed to synergistic interfacial
bonding mechanisms arising from the combined contributions of the electrochemically formed oxide
layer and the polymer–inorganic composite matrix.
Biocompatibility was assessed using fibroblast cell lines, demonstrating enhanced cell viability,
proliferation, and metabolic activity on the composite-coated titanium surfaces compared to the
unmodified substrate. These findings indicate that tailored composite coatings methodology can
significantly improve the biological performance of implants, supporting more efficient tissue
integration.
Overall, the results highlight the potential of hybrid organic–inorganic coatings obtained by coupled
electrochemical–electrophoretic processing as a promising strategy for next-generation biomedical
and dental implants. Their combination of strong adhesion, favorable surface morphology, and
excellent cytocompatibility positions the investigated coatings as viable candidates for improving
implant–tissue interactions and long-term clinical outcomes
PVDF/ZnO nanocomposite applications in the development of piezoelectric MEMS sensors: Theoretical Considerations
No full textPoly(vinylidene fluoride) (PVDF) is a semi-crystalline polymer known for its excellent pyroelectric and piezoelectric properties. While its dielectric permittivity is lower than that of piezoelectric ceramics, PVDF offers notable advantages for sensing applications, such as low density, mechanical flexibility, and toughness. These characteristics have made PVDF a popular choice in MEMS technology, as well as in ultrasound transducers and medical ultrasound systems. PVDF can crystallize into five different phases -phase is the most desirable for MEMS applications due to its superior electroactive properties. The analysis of PVDF and PVDF-based nanocomposites with ZnO as a filler has shown that the proportion of the beta phase increases with the addition of mechanically activated ZnO powder, thereby improving the piezoelectric properties of the material. These materials could therefore find applications in the development of piezoelectric MEMS sensors. Among them are highly sensitive chemical and biological thin film bulk acoustic wave resonant (FBAR) sensors. In this paper we presented the results of the theoretical analysis of sensor noise, which arises from the stochastic nature of the physical processes underlying the operation of adsorption sensors. Such analysis is important since it enables the estimation of sensors' limiting performance, and provides the guidelines for the optimization of sensor design during the development process