This paper presents methods for the production of nanoscale coke powders for bitumen modification. The chemical vapor deposition (CVD) method enables the production of nanopowders with particle sizes ranging from 14 to 30 nm at temperatures of 1000–1200 oC. Bitumen modification was performed by adding nanoscale coke powders, in accordance with the requirements of Kazakhstan standard 1373–2013. The nanosized powders were obtained by CVD in an inert nitrogen atmosphere with a specific surface area of 24.8 m2/g. Modification of bitumen with nanoscale coke yields grades with high thermal stability, ensuring optimal structural strength and durability of the pavement. Rheological studies show that nanoscale coke acts as an active structure-forming agent rather than an inert filler. The restriction of asphaltene mobility leads to a consistently reduced phase angle (δ) and the absence of a transition to a viscosity-dominated regime. The samples are characterized by the lowest phase angle values across the entire range of the complex modulus. This indicates the formation of a highly developed elastic-viscous structure due to the presence of nanosized coke, which promotes the formation of a percolating physical network and restricts the mobility of the bituminous system. The observed behavior indicates the dominance of the elastic component and the increased structural organization of the resulting bituminous binders.
Coordination compounds of Cu(II) ions with some oxyphosphonates were synthesized in ethanol using ultrasonic activation. The complexes were isolated as blue crystalline powders in yields of 72–87%. Complex formation was confirmed by IR spectroscopy and thermal analysis. The shift of the ν(P=O) band to lower frequencies indicates the involvement of the phosphoryl oxygen in coordination with the Cu(II) ion. Changes in melting points compared to the initial ligands indicates a rearrangement of the crystal structure. For the piperidine based complex, the N,O coordination type was observed by the appearance of a Cu–N absorption band at 661 cm⁻1. The biological activity of the synthesized compounds was evaluated using a wheat seed germination model. It was found that the oxyphosphonates and their complexes stimulate seedling development, leading to increased shoot and root lengths compared to the control. The most pronounced effect was observed for compounds containing phenyl and piperidine moieties, with root length increases reaching 74.8% and shoot length by 18.7%, relative to the control. In addition, the copper complexes suppressed the growth of mold microflora on treated seeds, exhibiting antimicrobial activity. These results demonstrate the potential of phosphorus-containing Cu(II) coordination compounds as potential agrochemicals with growth-promoting and antimicrobial properties.
The formation of hydrogen fluoride (HF) during the auto-ignition process of stoichiometric difluoromethane (R32)-air mixtures is numerically investigated in a cylindrical vessel under the influence of heat losses and heterogeneous wall reactions. Both slow reaction and successful explosion regimes are analyzed to study the thermo-kinetic conditions leading to HF formation. A detailed chemical mechanism is used for the gas-phase chemistry, while heterogeneous destruction reactions of reactive species at the wall surface are additionally considered. The effects of initial temperature, pressure and surface destruction efficiencies on HF production are investigated. Particular attention is paid to the role of OH radicals and heterogeneous wall reactions in controlling the formation of HF under non-explosive conditions.
This review article systematizes current knowledge on the catalytic hydrogenation of benzene as a key process in petrochemistry, environmental protection, and hydrogen energy technologies. The fundamental mechanisms of benzene ring activation and molecular hydrogen dissociation on transition metal surfaces are discussed, with particular emphasis on the disruption of aromatic stability as the rate-limiting step of the reaction. Special attention is given to the challenge of achieving selective benzene hydrogenation in the presence of other aromatic compounds, a situation typical of reformate and pyrolysis gasoline fractions. The influence of the active metal type (Ni, Pd, Pt, Ru), catalyst supports (oxide, zeolitic, carbon-based, and natural materials), and reaction parameters (phase, temperature, and hydrogen pressure) on catalytic activity, selectivity, and stability is systematically analyzed. Competitive adsorption among aromatic compounds, the role of electronic and steric effects of substituents, and mass-transfer limitations in liquid-phase systems are also examined. Results obtained for both industrial and emerging catalytic systems are summarized, including catalysts for the deep and partial hydrogenation of benzene, as well as their potential applications in liquid organic hydrogen carrier (LOHC) technologies. Achieving high selectivity therefore requires comprehensive optimization of catalyst composition, support structure, and process conditions, which defines the main directions for future research.
The paper presents the synthesis of a solid hydrocomposite material in a water-glycerol medium based on [MoO4]2–, Zr4+, Er3+, and Na ions in a 1:1:1:3 molar ratio using directional mixing of solutions in a U-shaped vessel. X-ray diffraction analysis confirmed the partially amorphous structure of the synthesized product. Infrared spectroscopy revealed the presence of bound water molecules and characteristic functional groups, including hydroxyl, aliphatic, and metal-hydroxide fragments, as well as bands characteristic of [MoO4]2– ions. Elemental and atomic emission analyses confirmed the presence of all the initial ions and revealed the molar ratio of the elements. X-ray microanalysis demonstrated chemical heterogeneity of the solid phase, while electron microscopy revealed an overall morphological homogeneity of the particles. Investigation of the luminescent properties showed the superposition of several peaks in the visible spectrum associated with transitions in the 4f shell of erbium ions, indicating the material's potential for applications in biomedicine, sensors, and optoelectronics. Thermal analysis further confirmed the presence of chemically bonded water molecules. The obtained results provide a basis for further investigation and targeted modification of the properties of such hydrocomposite systems.
This paper reports the electrochemical characteristics of supercapacitor pouch cells assembled on the basis of activated carbon YP80F and two types of aqueous electrolytes: 5 M LiTFSI + 0.5 M NaI (redox-active electrolyte) and 10 M LiTFSI (neat electrolyte). A comparative analysis was performed using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCPL) methods in the voltage range from 0.6 to 1.5 V. It was found that the system with the addition of NaI demonstrates pronounced effects on overall performance due to reversible I⁻/I2 redox processes, which provides an increase in specific capacitance to 128 F/g and energy to 9.26 W·h/kg at a voltage of 1.5 V while maintaining high Coulombic efficiency (>97%). In contrast, the supercapacitor with 10 M LiTFSI electrolyte exhibits classic electric double layer (EDL) behavior and lower specific capacitance (64 F/g) but high stability and reversibility (efficiency >99%). A comparative analysis showed that the hybrid supercapacitor pouch cell with NaI is more promising for tasks requiring high energy density, while concentrated LiTFSI-based system is preferable for applications focused on durability and stability. The results obtained contribute to the understanding of charge accumulation mechanisms in aqueous supercapacitors and open up prospects for optimizing their characteristics depending on the target operating conditions. The results highlight that the 5 M LiTFSI + 0.5 M NaI electrolyte enhances energy density through I⁻/I2 redox reactions, while the 10 M LiTFSI system offers superior stability, demonstrating a trade-off between energy density and long-term performance.
Scalable deposition of high-quality perovskite films is a key challenge for the commercialization of flexible perovskite solar cells. In this work, the deposition process and material properties of printed mixed-cation, mixed-halide perovskite films with the composition Cs0.175FA0.75MA0.075Pb(I0.88Br0.12)3 were systematically optimized using slot-die printing techniques. The influence of key printing parameters, including ink flow rate, coating speed, and substrate temperature, on film thickness, morphology, crystallization behavior, and optical properties was investigated. Optimized conditions enabled the formation of uniform perovskite layers with a thickness of 300–400 nm, a dense microstructure, and strong optical absorption with a bandgap of approximately 1.55 eV. The effects of solvent engineering and crystallization additives were further evaluated. While the pristine DMSO-based formulation provided structurally high-quality films, the incorporation of 5 mol% methylammonium chloride (MACl) significantly improved the film morphology, grain connectivity, and reproducibility without altering phase purity. Consequently, printed flexible perovskite solar cells fabricated with MACl exhibited enhanced short-circuit current density, fill factor, and power conversion efficiency (PCE), reaching a best PCE of 9.72%. These results demonstrate an effective strategy for controlling perovskite film formation in fully printed flexible devices and highlight the potential of MACl-assisted slot-die printing for flexible perovskite photovoltaics.
The corrosion inhibition of carbon steel (CS) in a 1 M HCl solution using the alkaloid extract from Glaucium flavum (AEGF) was investigated through a comprehensive and rigorous approach, including weight-loss measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The results demonstrate that the inhibition efficiency of AEGF increases with concentration, reaching a maximum value of 81% at 200 ppm, but decreases at elevated temperatures. Potentiodynamic polarization studies reveal that AEGF acts as a mixed-type inhibitor, affecting both anodic and cathodic reactions. The adsorption behavior of the extract follows the Langmuir adsorption isotherm model. Thermodynamic parameters, including the apparent activation energy, enthalpy, and entropy of the dissolution process, were also evaluated, confirming that the inhibition mechanism is predominantly physisorption. The results obtained from different methodologies were consistent and mutually corroborative. In addition, surface analysis by scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS) showed that samples treated with the extract exhibited a smoother surface compared with untreated samples. This smoother surface morphology indicates reduced corrosion due to the decreased exposure of the metal surface to the corrosive medium, which was further confirmed by profilometry analysis. A theoretical study based on conceptual density functional theory (DFT) was also conducted to predict the reactive sites of the molecules. These predictions were based on the analysis of both local and global chemical reactivity indices.
Organophosphorus pesticides (OPP), such as malathion (MTN), methyl parathion (MP), and chlorpyrifos (CHL), are widely used in agriculture to control pests and increase crop yields. However, their persistent residues in vegetables, fruits, and drinking water pose significant threats to human health, including neurotoxic and carcinogenic effects. Therefore, the development of efficient detection methods with high sensitivity, selectivity, and rapid response is of great importance. Among various analytical approaches, electrochemical methods have attracted considerable attention due to their simplicity, low cost, potential for miniaturization, and suitability for field applications. This review presents an overview of recent advances in electrochemical sensors for the detection of common OPP. Various approaches to the surface modification of working electrodes are described, including the use of nanomaterials, polymers, and metal-organic frameworks. The mechanisms of electrochemical oxidation and reduction of pesticides, as well as key analytical parameters of sensors – such as detection limit, linear range, sensitivity, and selectivity – are analyzed. Current problems, including interference from coexisting compounds and long-term sensor stability, are also discussed. In addition, future research directions are outlined, such as integration with portable devices and applications in real-world samples. This review contributes to a deeper understanding of current trends and challenges in the development of advanced electrochemical sensors for OPP monitoring.
This study presents a hierarchically structured, free-standing rGO/MoS2 hybrid film fabricated through a facile vacuum filtration and thermal reduction approach, offering a cost-effective strategy for high-performance K-ion supercapacitors. The optimized composite architecture features nanoporous, layer-stacked channels and expanded interlayer spacing, enabling efficient ion diffusion and abundant electroactive sites. The rGO/MoS2 electrode demonstrates exceptional capacitive performance, delivering a gravimetric capacitance of 378 F g-1 and a record volumetric capacitance of 787 F cm-3 at 1 A g-1, attributed to the synergy between the conductive rGO network and the pseudocapacitive properties of MoS2. The symmetric supercapacitor cell assembled with rGO/MoS2 electrodes and an aqueous electrolyte (3 mol L-1 KOH) demonstrated a high energy density of 7.6 mWh cm-3 with power density of 0.36 W cm-3, whereas supercapacitor with organic electrolyte (1 mol L-1 MeEt3NBF4) displayed 26 mWh cm-3 at 1.4 W cm-3. Both supercapacitors showed excellent cycling lifespan with capacitance retention of 100% after 480,000 and 270,000 cycles, respectively. These findings suggest the excellent electronic conductivity of rGO and the electrochemically active MoS2 synergistically contribute to the outstanding supercapacitor performances.
Diabetes is one of the most significant global health challenges. With synthetic drugs causing side effects, researchers are turning to natural alternatives for prevention and treatment. This study used molecular docking to predict the interaction of flavonoids from Verbascum spp. and their affinity for binding to α-glucosidase (3WY1) and DPP-IV (5J3J) enzymes. Binding energies, hydrogen bond interactions, and hydrophobic contacts at the active sites were analyzed. Kaempferide stood out against α-glucosidase with the lowest binding energy (‒5.03 kcal/mol), forming strong hydrogen bonds to GLU231 (1.70 Å), LEU300 (1.95 Å), and ASN301 (2.00 Å). Luteolin 7-O-β-D-glucopyranoside showed weaker binding (‒3.37 kcal/mol) with bonds to GLU383 (1.88, 2.29 Å) and TRP394 (2.45 Å). For DPP-IV, luteolin had the best affinity (‒6.01 kcal/mol), creating five hydrogen bonds with GLY335 (1.92, 2.11 Å), SER277 (2.08 Å), TRP337 (2.82 Å), and SER275 (2.99 Å). These results position kaempferide and luteolin as promising candidates for developing natural antidiabetic agents from Verbascum species.
The aim of the present study is to identify the preferred region of the thermodynamic surface for the separation of a mixture of ethyl esters of oleic and palmitic fatty acids within the framework of the authors' original method. This method is based on the concept of the dual nature of the mass transfer mechanism in supercritical fluid extraction processes for systems exhibiting type I and II phase behavior. Results are presented for the separation of a binary mixture of ethyl oleate and ethyl palmitate. The process was carried out in asymptotic proximity to the critical point of the CO2–ethyl oleate system. As a result, in one of the extract samples, an ethyl oleate concentration of 94 wt.% was achieved within a 20-minute process duration, starting from an initial content of 25.28 wt.% in the feed mixture. A comparison with the separation results obtained for the same mixture under asymptotic proximity to the critical point of the CO2–ethyl palmitate system revealed the superiority of the aforementioned conditions. The proposed separation method is not limited to the specific mixture discussed here and is proposed for the first time.
Ephedrine and its derivatives have long been recognized for their therapeutic potential in the treatment of hypotension, asthma, and obesity. However, their use is limited by significant side effects, including cardiovascular risks and toxicity. This study presents a comprehensive computational evaluation of 13 ephedrine derivatives using integrated ADMET analysis, PASS prediction, and quantum-chemical approaches. Pharmacological profiles, toxicity risks, and electronic properties were systematically analyzed to establish structure–activity relationships. Key physicochemical parameters, pharmacokinetic properties, and toxicity risks were analyzed to identify compounds with optimal drug-like characteristics. The results highlight compound 5 as the most promising candidate, demonstrating high drug-likeness (Quantitative Estimate of Drug-likeness, QED = 0.85) and favorable pharmacokinetic properties. Conversely, compounds 3, 11–13 exhibit high toxicity and require structural optimization. PASS predictions indicate diverse biological activities, including spasmolytic and analeptic effects, with compounds 5–7 showing significant potential for further development and compound 13 exhibiting antioxidant activity. DFT analysis of ephedrine, cephedrine and key derivatives (compounds 5, 7, 13) revealed an optimal HOMO-LUMO range (ΔE = 4.7–5.0 eV) for compounds with high activity and low toxicity, where derivative 5 exhibits the best balance. This study underscores the importance of rational drug design in optimizing therapeutic efficacy while minimizing adverse effects and environmental risks.
The complexity of the combustion process makes the computational time using a detailed mechanism unacceptable, therefore, it is necessary to simplify the mechanism. The reaction-diffusion manifolds (REDIM) method is a reduction model that takes the coupling of molecular diffusion and chemical reactions into account to reduce computing times, and can be utilized in different types of combustion simulations. In this work, the REDIM method is implemented into a new OpenFOAM-based CFD solver. The use of both generalized and physical coordinates to represent the manifold is analyzed for freely propagating laminar flames. The REDIM-based solver is then used to calculate 2D laminar counterflow flames. Different detailed mechanisms, progress variables and inlet velocities are applied to calculate the 2D counterflow flames and to evaluate the performance of REDIM at steady and extinction conditions. It is shown that the results computed by the REDIM method have good agreement with the results obtained by detailed simulations. Furthermore, the REDIM method offers a significant reduction in computational cost in the newly developed solver.
The growth in energy consumption and the limited nature of fossil resources are driving the search for alternative energy sources. Hydrogen is an environmentally friendly fuel, especially when produced by water electrolysis. However, its efficiency depends on the overpotential at the electrodes, which is related to the choice of catalyst. Noble metals, such as platinum, are effective but expensive. An alternative is catalysts based on transition metals, especially in alkaline media, where they are more resistant to corrosion. Oxides, nitrides, sulfides, and phosphides exhibit the highest catalytic activity; however, their efficiency is limited due to particle aggregation and poor adhesion to the substrate. MXene materials – layered transition metal carbides and nitrides – possess high electrical conductivity, stability, and potential for modification. They form robust freestanding electrodes, effectively bind with additives, and provide a large contact area with the electrolyte. This review analyzes hydrogen evolution reaction catalysts in alkaline media based on MXene and its modifications. Key relationships between the composition, structure, and activity of the catalysts are identified, and pathways to improve the quality of research in this field are proposed.
Estrogen plays a critical role in the development and progression of hormone-sensitive breast cancer. Aromatase (CYP19A1), the key enzyme catalyzing the final step in estrogen biosynthesis, has emerged as a promising therapeutic target. Although third-generation synthetic aromatase inhibitors (AIs) are effective, their use is limited by serious side effects, highlighting the need for safer natural alternatives. In this study, we evaluated three major flavonoids from Tussilago farfara L., quercetin-3-rutinoside (1), quercetin-3-O-β-D-glucoside (2), and kaempferol-3-O-glucoside (3) for aromatase inhibitory potential. In vitro assays showed that compound 3 was the most potent (IC50 = 3.46 µM), followed by compound 2 (3.79 µM) and compound 1 (3.81 µM), with activities comparable to potent dietary flavonoids and stronger than some reported natural analogues. Molecular docking supported these findings, showing favourable docking scores (-6.73 to -4.19) and binding energies (-60.3 to -43.7 kcal mol-1), comparable to those of the standard inhibitor exemestane (IC50 = 0.20 µM; -68.3 kcal mol-1). However, the computational predictions did not fully replicate the experimental ranking, reflecting the limitations of docking methods. Overall, these results highlight the significance and therapeutic potential of T. farfara flavonoids as natural aromatase inhibitors.
Since the fundamental work of Gibbs, many models have been proposed to describe the interfacial properties of adsorbed surfactant layers. The historical models of von Szyszkowski, Langmuir, and Frumkin are presented here together with their advantages and shortcomings. Only during the last few decades have additional adsorption models been developed by Fainerman and co-workers. These models allow describing particular details of surfactants adsorbed at liquid interfaces. They are derived from the fundamental thermodynamic principle of Braun–Le Châtelier and allow us to assume that surfactant molecules may adsorb in different adsorption states or form small two-dimensional aggregates. The most recently discussed multistate model assumes more than two coexisting adsorption states, which has been shown to be particularly suitable for surfactant molecules capable of undergoing conformational changes upon adsorption. The classical models of Langmuir and Frumkin, as well as the newer multistate models, are all of practical importance for the respective types of surfactants.
This study investigates the formation and characteristics of inclusion complexes between β-cyclodextrin and two compounds: N-aminomorpholine hydrazone and its phthalimidine derivative. Structural features of the encapsulated forms of these new N-aminomorpholine derivatives were characterized using 1H and 13C NMR spectroscopy, as well as two-dimensional 1H─1H (COSY) and 1H─13C (HMBC, HSQC) NMR experiments. Using molecular modeling methods, the influence of structural factors and the principle of geometric complementarity on the complexation processes between the host and guest molecules were assessed. A conformational study of the guest molecules was carried out using the semiempirical GFN2-xTB method in combination with the GOAT algorithm. Employing density functional theory (DFT), the inclusion complexes were optimized at the ωB97X-D/6-311G(d,p) level, including aqueous solvation effects as described by the CPCM model. The thermodynamic parameters of complex formation were estimated. NMR analysis confirmed 1:1 stoichiometry and showed significant chemical shift perturbations for cavity protons, while DFT calculations revealed spontaneous complexation (ΔG°298 = −2.54 to −3.45 kcal/mol) driven by exothermic enthalpies and hydrophobic/van der Waals interactions, with an enantioselective preference for the R-phthalimidine enantiomer. These findings demonstrate β-CD's potential to enhance the solubility, stability, and bioavailability of these promising antiviral and antibacterial agents for pharmaceutical applications.
Photocatalytic CO2 reduction offers a dual benefit of mitigating greenhouse gas emissions while generating renewable fuels. In this study, a composite photocatalyst based on aluminum-doped strontium titanate (Al-STO) was synthesized via a flux method and modified with dual cocatalysts: metallic Ag (reductive site) and a Ni-based species (oxidative site). Sequential photodeposition enabled precise loading, yielding a catalyst with enhanced charge separation and suppressed recombination. Structural and spectroscopic analyses confirmed the uniform dispersion of cocatalysts and broadened light absorption into the visible range. Photocatalytic evaluation under simulated solar light revealed a more than twofold increase in CO production (24.2 µmol·g⁻¹·h⁻¹) and high selectivity (up to 99%), compared to pristine Al-STO. The observed performance enhancement is attributed to the synergistic interaction between Ag and the Ni-based cocatalyst, enabling spatially resolved charge carrier pathways. These results highlight the promise of cocatalyst engineering on perovskite surfaces for selective CO2-to-fuel conversion under solar irradiation.
Controlled injection of kinetic hydrate inhibitors (KHIs) is one of the most effective flow-assurance strategies for delaying hydrate nucleation and crystal growth in multiphase natural gas pipelines. To enhance the structure of the kinetic inhibitor polyvinyl caprolactam (PVCap), oxyethyl and ester functional groups were introduced, resulting in the development of a new inhibitor, PVCap-XA1. PVCap-XA1 has been applied to achieve enhanced inhibition performance against methane hydrate formation. The structural and morphological changes in methane hydrates formed in the presence of PVCap-XA1 were investigated using advanced characterization techniques, including PXRD, low-temperature Raman spectroscopy, and cryo-SEM. Under identical experimental conditions, PVCap-XA1 demonstrates higher kinetic inhibition efficiency compared with PVCap. Microscopic analysis indicates that the clathrate structure of methane hydrate remains unchanged; however, PVCap-XA1 induces lattice-plane distortions that result in smaller crystallites. In the presence of PVCap-XA1, the induction time for hydrate formation was extended to approximately 240 min, and the maximum subcooling increased to 10.8 °C, compared with 8.1 °C for PVCap. In addition, PVCap-XA1 alters the cage occupancy ratio (IL/IS), making it more difficult for methane molecules to occupy hydrate cages. PVCap-XA1 also modifies the microscopic morphology of methane hydrate, shifting it from a porous to a dense, compact structure. This densification blocks gas flow through the hydrate layer, further enhancing inhibition efficiency. Overall, the results demonstrate that PVCap-XA1 is a promising kinetic inhibitor capable of addressing industrial challenges associated with methane hydrate formation in pipelines.
