Search Results (870)

Aging of Styrene–butadiene–styrene (SBS)-modified asphalt accelerates the degradation of both the SBS polymer network and asphalt components, resulting in deterioration of the durability of asphalt concrete. This study investigates the use of zinc diethyldithiocarbamate (ZDC), a multifunctional antioxidant, in SBS-modified asphalt to improve its aging resistance. Physical property tests, dynamic rheological analysis, multiple stress creep recovery (MSCR) and Fourier transform infrared spectroscopy (FTIR) assays were conducted to evaluate the rheological and chemical properties of asphalt binders before and after thermo-oxidative and UV aging. The results indicate that the incorporation of ZDC improved the deformation resistance and elastic recovery of SBS-modified asphalt. After aging, the ZDC/SBS composite-modified asphalt exhibited lower performance change rate than conventional SBS-modified asphalt, indicating enhanced resistance to permanent deformation and aging-induced damage. FTIR analysis demonstrated that ZDC effectively inhibited the formation of oxygen-containing functional groups during aging, suggesting suppressed oxidative reactions within the asphalt binder. The 5% ZDC dosage reduces the carbonyl index of SBS-modified asphalt by 36.48% after thermo-oxidative aging, and by 21.89% after UV aging, showing a stronger chemical inhibition effect on thermo-oxidative reactions. From the perspective of rheological performance stability, ZDC lowers the variation amplitude of non-recoverable creep compliance by 35.32% before and after thermo-oxidative aging and 41.46% before and after UV aging, and delivers a more prominent mitigating effect on property fluctuations triggered by UV aging. This indicates that ZDC exerts differentiated anti-aging mechanisms on thermo-oxidative and UV aging, with considerable potential to improve the comprehensive aging resistance of polymer-modified asphalt binders. Full article

Wastewater containing heavy metals and dyes poses serious environmental risks. This study developed a multifunctional composite by coating polyurethane foam (PUF) with milled activated carbon (mAC) and a zirconium-based metal–organic framework (Zr-MOF) for the simultaneous removal of hexavalent chromium (Cr(VI)) and Congo red (CR). The composite was synthesized using a hydrothermal method to grow Zr-MOF on the surface. The SEM analysis confirmed the successful incorporation of mAC and surface modification with Zr-MOF, which resulted in increased surface roughness and porous morphology. XRD and FTIR confirmed the presence of organic ligands connected to the metal structure and the functional groups of each component in composite materials. The optimum conditions for Zr-MOF/mAC/PUF adsorption (nearly 100% removal) in the binary Cr(VI)/CR solution (50 mg/L each) were 25 °C, pH 9, and 150 rpm for 24 h. The Zr-MOF/mAC/PUF was hydrophilic with a swelling ratio of 2.64 g/g. The thermodynamic investigation of Zr-MOF/mAC/PUF resulted in 141.6218 kJ/mol for Cr(VI) and 166.111 kJ/mol for CR of ΔH° (rapid adsorption), negative ΔG° (spontaneous adsorption), a high positive value of ΔS° (disorder structure) and low activation energy (approximately 2.5 to 2.8 kJ/mol). After analyzing the isotherm and reaction kinetics, the possible mechanism could be endothermic physicochemical adsorption and pseudo-second-order kinetic behavior, with electrostatic attraction and diffusion control. The study of 6-times-reused Zr-MOF/mAC/PUF adsorption identified as a decrease of 7.55 percentage point without changing notable morphology and functional groups, based on SEM and FTIR. Full article

Bilateral deficit (BLD) is traditionally defined as the reduced capacity to produce force during simultaneous bilateral contractions compared with the summed output of unilateral actions. However, in applied sport settings, BLD is frequently estimated from countermovement jump (CMJ) performance, representing a functional rather than a direct mechanical measure of force production. Therefore, the aim of this study was to examine the association between a CMJ-derived functional BLD index and multidirectional performance in soccer players. Forty male university soccer players (age: 23 ± 1 years) performed unilateral and bilateral CMJ. The BLD index was calculated from jump height values obtained during these assessments. Participants subsequently completed the 505 change-of-direction (CoD) test, which was analyzed using two-dimensional video-based motion analysis. Participants were classified according to BLD magnitude into low, moderate, and high BLD groups. Group differences were assessed using Kruskal–Wallis tests with Bonferroni-adjusted post hoc comparisons. Additionally, Spearman correlation analyses were performed using BLD as a continuous variable. Significant between-group differences were observed across all temporal phases of the 505 test (p < 0.001), with players exhibiting lower BLD values demonstrating superior acceleration, deceleration, reacceleration, and overall CoD performance. Significant negative correlations were also observed between BLD and reaction time, acceleration, deceleration, reacceleration, CoD time, and CoD deficit (r_s = −0.42 to −0.69; p < 0.001). No significant associations were found for stride length, acceleration ability, or inter-limb asymmetry. These findings suggest that lower magnitudes of a CMJ-derived functional BLD index are associated with superior multidirectional performance in soccer players. However, given that BLD was estimated from jump performance, the results should be interpreted as associations with a functional neuromuscular performance index rather than as direct evidence of bilateral force production capacity. Full article

To investigate the impact resistance of hybrid fiber-reinforced recycled aggregate concrete (RAC) under dry–wet cycles and sulfate attack, hybrid fiber-reinforced recycled aggregate concrete (RAC) was prepared. Dynamic impact compression experiments were conducted using an SHPB test device with a 50 mm diameter. The microstructure of recycled aggregate concrete (RAC) within dry–wet cycles and sulfate attack was examined using SEM. The results indicate that the dynamic compressive strength first rises and then declines with the rise in dry–wet cycles, and increases with the increase in the average strain rate. When the number of dry–wet cycles reaches 16, the dynamic compressive strength reaches its peak, with the B4S6 group achieving a maximum dynamic compressive strength of 59.02 MPa. The dynamic elastic modulus follows a good quadratic parabolic function distribution with respect to the number of dry–wet cycles. Both the incident energy and dissipated energy density initially rise and then reduce with increasing dry–wet cycles. The energy values of RAC with different fiber types follow the order: B4S6 > S6 > B4 > RAC. Under impact loading, the strain rate–strain time history curve of recycled aggregate concrete (RAC) exhibits the change of “increase–decrease–stable–decrease”. With increasing dry–wet cycles, the degree of fragmentation of recycled aggregate concrete (RAC) first increases and then decreases, the fractal dimension first decreases and then increases, and the average particle size first increases and then decreases. SEM results and microscopic reaction mechanisms reveal that in the early stage of dry–wet cycles, sulfate ions generate ettringite and gypsum within the recycled aggregate concrete (RAC), which fill internal cracks and pores, making the concrete denser and enhancing its mechanical properties. Towards the end of the dry–wet cycle, the amount of expansive ettringite and gypsum inside the recycled aggregate concrete (RAC) increases, leading to a sharp increase in pore wall stress, which induces new microcracks in the specimens, manifesting as a decline in mechanical properties at the macroscopic level. Full article

The physicochemical characteristics of hydrochars produced from tobacco stems through hydrothermal carbonization (HTC) at different temperatures were investigated, along with the variation in contents of nicotine, niacin, and chlorogenic acid in both the hydrochars and the liquid phase. The results indicated that dehydration was the predominant reaction during HTC of wet tobacco stems (WTS), leading to a decrease in the H/C and O/C atomic ratios of the hydrochars. As temperature increased, polycondensation and aromatization reactions became more pronounced, which corresponded with a reduction in the intensity of functional group vibrations such as C–N and N–O in FT-IR spectra. XPS analysis revealed a gradual increase in C=O content, whereas the proportions of C–OH and C–O bonds declined from 51.74% and 35.13% to 36.95% and 20.84%, respectively. Furthermore, the content of pyridine-N rose from 31.08% to 41.30%, while pyrrole-N and quaternary-N contents decreased to varying degrees. Both nicotine and niacin levels in the hydrochars and carbonization liquids exhibited an initial increase followed by a decline, whereas chlorogenic acid content consistently decreased. The underlying mechanisms for the observed changes in nicotine, niacin, and chlorogenic acid contents during HTC are discussed in detail. Full article

Background: Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely recommended for the treatment of acute (low) back pain, despite modest effectiveness and well-known safety concerns, particularly in older patients. Pridinol is a centrally acting antispasmodic with a mechanism-oriented approach targeting muscle spasm, a key component of acute back pain. While a previous real-world analysis demonstrated a significantly better tolerability and effectiveness of pridinol compared with NSAIDs, age-dependent effects have not yet been systematically evaluated. Objective: To assess the age dependency of effectiveness, safety, and tolerability of pridinol versus NSAIDs in patients with acute (low) back pain under real-world conditions, based on already available data. Methods: This secondary analysis used propensity score-matched real-world data from the German Pain e-Registry (PROVIDENCE study; EUPAS identifier: 49718). A total of 934 patients with acute (low) back pain treated for four weeks with either pridinol (n = 467) or NSAIDs (n = 467) were stratified by age (<65 vs. ≥65 years). Outcomes included the incidence of adverse drug reactions (ADRs), ADR-related treatment discontinuations, time to ADR occurrence, and clinically meaningful improvement in pain-related disability (≥50% reduction in modified Pain Disability Index). Analyses were performed within and between age strata. Results: Overall, ADRs were reported by 9.0% of pridinol-treated patients and 20.8% of NSAID-treated patients (p < 0.001). In the pridinol cohort, ADR rates were virtually identical in patients <65 and ≥65 years (8.9% vs. 9.2%; p = 0.940). In contrast, NSAID-treated patients showed a pronounced age-related increase in ADR incidence (17.3% vs. 32.1%; p < 0.001). ADR-related treatment discontinuation rates under NSAIDs increased markedly with age (5.9% vs. 21.1%; p < 0.001), whereas rates under pridinol remained low and age independent (3.1% vs. 4.6%; p = 0.447). Gastrointestinal and cardiovascular ADRs were the main contributors to the age-related risk increase under NSAIDs, while corresponding events under pridinol were rare across age groups. Clinically meaningful improvement in pain-related disability was achieved with pridinol/NSAIDs in 91.9/48.0% (<65 years) and 88.1/47.7% (≥65 years; p < 0.001 for both). Conclusions: Age is a major modifier of NSAID-related risk but not of pridinol tolerability in acute (low) back pain. While NSAID-associated ADRs and treatment discontinuations increase substantially in patients aged 65 years or older, pridinol demonstrates a stable, age-independent safety profile combined with significantly better functional outcomes. These findings suggest that, particularly in older patients, mechanism-oriented alternatives such as pridinol may offer a more favorable benefit–risk profile than NSAIDs. Full article

Electrospun sulfonated polyketone (PK) nanofiber membranes were prepared to investigate the sulfonation-time-dependent structure–property relationships of hydrocarbon-based polymer electrolyte membranes for PEMFC (Polymer Electrolyte Membrane Fuel Cell) applications. NaCl addition to the electrospinning solution increased solution conductivity and enabled the formation of uniform PK nanofibers with an average diameter of approximately 270 nm. Subsequent sulfonation introduced sulfonic-acid-related groups into the PK nanofiber framework, and the resulting membrane properties were strongly governed by sulfonation time. Among the tested membranes, PK-NC16 exhibited the highest proton conductivity of 0.107 ± 0.031 S cm⁻¹ and an ion exchange capacity of 2.82 m_eq g⁻¹, exceeding or comparable to those of Nafion 115 under the tested conditions. FTIR-based analysis indicated that the relative sulfonation index increased up to 16 h, whereas extended sulfonation for 24 h generated additional sulfone/sulfonate-related bands, suggesting possible side reactions or structural changes under prolonged acid treatment. The high water uptake of PK-NC16 enhanced proton transport but also revealed a hydration-sensitive polymer network, as reflected by a voltage degradation rate of approximately −590 μV h⁻¹ during a 100 h short-term stability constant-current test. These results demonstrate that sulfonation time is a key parameter controlling the balance among ionic functionality, hydration, mechanical response, proton conductivity, and PEMFC-relevant single-cell performance in electrospun PK nanofiber membranes. Full article

Coal spontaneous combustion (CSC) remains a major hazard in coal mining. Research on CSC has largely focused on macromolecular structures, while the behavior of low-molecular-weight compounds remains unclear. Using B3LYP/6-311G density functional theory, this study systematically reveals thirteen microscopic reaction pathways, active sites, and the energy barrier order of pentanol during coal spontaneous combustion. The oxidation proceeds via thirteen multi-step pathways involving bond breaking and formation, with the dominant reaction being oxygen attack on the -CH₂OH group to produce pentanal (CH₃CH₂CH₂CH₂CHO) and water as the main products. The priority order of thirteen reaction pathways between pentanol and oxygen was established as: Path 6 > Path 3 > Path 8 > Path 5 > Path 4 > Path 1 > Path 11 > Path 10 > Path 9 > Path 12 > Path 7 > Path 2. The results reveal the multi-step bond-breaking and formation mechanism at the molecular level, providing a fundamental theoretical framework for understanding the radical chain oxidation mechanism of low molecular weight compounds in CSC. Full article

A comparative density functional theory (DFT) study was performed to elucidate the mechanistic details of Schiff base formation between 3-pyridinecarboxaldehyde and the three positional isomers of aminobenzoic acid (o-, m-, and p-). Both single proton transfer (SPT) and methanol-assisted double proton transfer (DPT) pathways were systematically investigated in the gas phase and within a polarizable continuum model (PCM) for methanol. All stationary points were optimized at the B3LYP/6-31G and 6-311++G(d,p) levels, and transition states were confirmed by vibrational frequency and intrinsic reaction coordinate (IRC) analyses. The results reveal that the DPT mechanism is consistently associated with significantly lower activation free energies compared to the direct SPT pathway, particularly in methanol, where solvent-mediated proton relay markedly stabilizes the transition states. The positional effect of the amino group influences both the electrostatic potential distribution and the activation barriers, with the para isomer exhibiting enhanced nucleophilicity and improved reaction efficiency. These findings provide detailed mechanistic insight into solvent-assisted proton transfer processes in Schiff base synthesis and highlight the cooperative role of hydrogen-bond networks in reducing energetic barriers. Full article

The synthesis of reactive sucrose derivatives is of significant interest for the development of novel biocompatible polymers. In this study, an octa-substituted sucrose derivative containing isocyanate groups was synthesized via a urethane-forming reaction carried out in an aprotic solvent at the phase interface. This approach exhibits high selectivity and provides a target product yield of up to 60%. Subsequently, using the same reaction mechanism, the isocyanate derivative was converted into an octa-functional methacrylate derivative capable of forming three-dimensional cross-linked networks. The structures of both the intermediate and final products were confirmed by IR, ¹H NMR, and mass spectrometry. The sucrose-based prepolymer was further evaluated in the formation of cross-linked structures for potential application as bone-substituting implants. Using various photocuring techniques, including two-photon 3D printing, both plates and microstructured scaffolds were fabricated. These structures exhibited high thermal stability, elastic properties comparable to those of bone tissue, and no toxic effects on cells. Full article

Silica dispersion in rubber matrices remains a critical issue due to the polarity mismatch between silica and the rubber phase. This study aimed to synthesize functionalized liquid polyisoprene rubber (F-LIR) and evaluate its role in improving the interfacial interaction between silica and solution styrene–butadiene rubber (SSBR). F-LIR was synthesized by introducing an alkoxysilane-containing functionalizing agent at the termination stage of anionic polymerization. Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy (¹H-NMR) were used to confirm the successful introduction of silyl groups at the chain ends of liquid polyisoprene. The optimal loading of F-LIR in SSBR was evaluated through bound rubber content, dynamic mechanical analysis, and mechanical performance testing. The results demonstrated that F-LIR improved the tensile strength, modulus at 300% elongation, and bound rubber content of SSBR composites. These enhancements are attributed to the reaction between the silyl groups of F-LIR and surface hydroxyl groups of silica, together with the co-crosslinking interaction between F-LIR and SSBR. The composites containing 4 phr F-LIR exhibited the best overall balance of properties. This study provides a novel method for synthesizing F-LIR, which bridges silica and the rubber matrix by enhanced filler–rubber interactions at the filler–rubber interface. Full article

Carbon materials are regarded as cost-effective adsorbents due to their ability to remove heavy metals and organic pollutants from contaminated water. In this study, a novel phenol–formaldehyde resin-derived carbon microsphere (HCM_2.5) was designed and synthesized via a hard-template method combined with KOH activation. The prepared HCM_2.5 exhibits high selectivity and removal efficiency toward heavy metal ions and delivers an ultrahigh specific surface area of 2165 m²/g. A Cr(VI) removal efficiency exceeding 99.6% could be achieved in 50 ppm acidic solution, with excellent performance at pH 2–5. X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) nitrogen adsorption–desorption analysis, and scanning electron microscopy (SEM) were used to confirm its porous structure with a high specific surface area. The results of X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) reveal that the efficient heavy metal removal performance of HCM_2.5 is mainly attributed to its high specific surface area, as well as coordination and redox reactions between oxygen-containing functional groups and heavy metal ions. Furthermore, benefiting from its outstanding specific surface area and well-developed pore structure, a physical–chemical synergistic adsorption mechanism was proposed and systematically elucidated. Full article

The synthesis of hydroxamic acids from sterically hindered substrates, such as abietane-type resin acids, remains a synthetic challenge due to the congestion of the tricyclic skeleton. This study reports an efficient one-pot protocol for the direct conversion of abietic and dehydroabietic acids into their corresponding hydroxamic derivatives, achieving 65% and 74% isolated yields, respectively. Systematic screening of activating agents identified diethyl chlorophosphate (DCP) as the reagent for the hydroxyamidation. A critical finding of this work is that the optimization of the isolation process specifically minimizing the water amount during aqueous work-up was key to recovering these polar products and preventing important yield loss. The reaction proceeds through diethyl phosphate mixed anhydride intermediate, which was successfully isolated, providing direct experimental evidence of the activation pathway. The reaction mechanism was further elucidated using Density Functional Theory (DFT) calculations at the M062X/6-31G** level, identifying a concerted transition state for the simultaneous addition of hydroxylamine and expulsion of the phosphate group. Furthermore, the study rationalizes the observed chemoselectivity; although the ester is the more stable thermodynamic product, the formation of the N-hydroxy amide is kinetically favored through a substantially lower activation barrier. This combined experimental and theoretical approach establishes a practical and scalable methodology for the functionalization of abundant similar natural terpenoids. Full article

Background/Objectives: Aging is characterized by progressive functional decline associated with alterations in gut microbiota, epithelial barrier dysfunction, and cellular senescence. Although quercetin has been proposed as a potential anti-aging compound, its clinical application is limited by poor bioavailability. In this study, we investigated whether enhancing quercetin bioavailability using EubioQuercetin (EQN) modulates aging-related phenotypes through the gut microbiota–intestinal barrier axis. Methods: Male C57BL/6J mice were treated with EQN or conventional quercetin (CQN) for 12 weeks. External aging phenotypes were assessed using a composite aging score based on hair glossiness, hair loss, and the presence of white hair. Gut microbiota composition was analyzed via 16S rRNA sequencing with centered log-ratio transformation, and intestinal gene expression was assessed by quantitative reverse transcription-polymerase chain reaction. Results: EQN significantly reduced the aging score compared with the control group (median 4.5 vs. 8, p < 0.01), while CQN also showed a moderate reduction. Microbiota analysis identified taxa positively associated with aging (Lactobacillus, Romboutsia, Desulfovibrio, and Lachnoclostridium) and negatively associated taxa (Akkermansia and Christensenellaceae). EQN suppressed aging-associated taxa and partially increased taxa linked to a healthier microbiota profile. At the intestinal level, EQN downregulated senescence-associated genes (p21, PCNA, and Lgr5) and upregulated the tight junction gene claudin-1. In contrast, systemic inflammatory markers and short-chain fatty acids were not significantly associated with the aging score. Conclusions: These findings indicate that enhancing quercetin bioavailability attenuates externally assessed aging phenotypes in aged mice and is associated with coordinated changes in gut microbiota and intestinal gene expression. Modulation of the gut microbiota–intestinal barrier axis may represent a potential mechanism underlying these effects. Full article

In recent years, soil contamination by heavy metals and organic pollutants has become a serious environmental problem. Biochar is a highly carbonaceous, water-insoluble porous material made from biomass feedstock through a thermochemical conversion process, and it has been widely used in the remediation of various soil pollutants. However, previous reviews on the modification of biochar and the remediation reaction mechanism of heavy metals and organic pollutants by biochar in soil were still not sufficiently comprehensive. Based on the current research status of the remediation of heavy metals and organic pollutants by biochar in soil, this review systematically summarized biomass feedstock types, pyrolysis methods and their applicable scenarios, as well as the modification strategies of biochar, including pore structure modification, surface functional group modification, surface charge modification, and magnetic modification. It also comparatively discussed the adsorption of heavy metals by biochar mainly through electrostatic attraction, ion exchange, complexation/precipitation, cation−π interaction, and redox transformation, while the adsorption of organic pollutants via π−π/EDA interactions, electrostatic attraction, hydrogen bonding, hydrophobic partitioning, and pore filling were outlined. The review also discussed competitive effects among pollutants during biochar adsorption under co-contamination scenarios, as well as the synergistic interactions between biochar and soil microorganisms or plants. In addition, the review addressed recent progress in field-scale applications of biochar, as well as the current state of research on aging effects, ecological risks, and economic feasibility. Finally, it identifies key research directions that warrant further attention. This review highlighted the mechanistic differences between heavy metal stabilization and organic pollutant removal in soil by biochar, and provided mechanistic insight and guidance for biochar-based soil remediation. Full article