Performance and mechanism of lignin and quercetin as bio-based anti-aging agents for asphalt binder: A combined experimental and ab initio study

Health impacts of asphalt emissions: Examining neurological risks and the need for long-term exposure mitigation

Asphalt, widely used in infrastructure, emits complex chemical mixtures throughout its service life, posing significant risks to human health and the environment. This expanded understanding extends the concern from a construction-related hazard to a broader public health issue, especially affecting vulnerable populations like children who play on blacktop surfaces. Despite increased awareness, the specific mechanisms behind asphalt emissions, their impact on asphalt deterioration, and their effects on the human nervous system remain poorly understood. Our study addresses these knowledge gaps by examining the long-term health effects of asphalt emissions, focusing on neurological impacts. We investigate how environmental stressors and asphalt's chemical composition influence emission types and severity, using a combination of in vitro experiments, Drosophila melanogaster models, and advanced computational analyses. FTIR analysis reveals that as asphalt ages, emissions evolve from aliphatic to aromatic compounds, increasing toxicity. Our results demonstrate significant neurological damage from asphalt emissions, with effects worsening with age and being more pronounced in females, as shown in the Drosophila model, emphasizing the need for gender-specific health risk research. In vitro studies using 3T3L1 cells show that VOC exposure disrupts lipid droplet formation and metabolism, processes linked to neurodegenerative disorders. To mitigate emissions, our novel approach introduces wood-based biochar as a functional carbon to enhance intermolecular interactions within asphalt. GC-MS analysis indicates that biochar reduces VOC emissions by up to 76 %, while molecular dynamics (MD) simulations highlight biochar's effectiveness in hindering free-radical diffusion. Density functional theory (DFT) calculations confirm biochar's role, with adsorption energies of -20.4 kcal/mol, demonstrating strong and stable interactions that decelerate oxidative aging and mass loss. These findings offer a comprehensive understanding of emission mechanisms and propose a sustainable strategy to enhance asphalt durability while reducing environmental and health risks. This in turn provides evidence-based recommendations for the asphalt industry, emphasizing proactive measures toward long-term exposure mitigation. SYNOPSIS: Asphalt emits chemicals throughout its service life, posing neurological risks, especially to vulnerable groups, and needs emission mitigation.

Use of antioxidants to retard aging of bitumen: A review

Oxidative aging of bitumen is an inevitable and irreversible phenomenon. Exposure to detrimental factors such as sunlight, oxygen, and UV radiations accelerates the aging of bitumen and bituminous pavement. The aging process induces hardening and embrittlement in bitumen, leading to premature pavement failure. Therefore, for constructing sustainable long-lasting pavements anti-aging additives are used. Among the available additives, the use of antioxidants has emerged as a promising solution to mitigate the aging of bitumen. The current review aims to summarise the existing literature for a comprehensive understanding of the effectiveness of these additives as aging inhibitors. It provides an overview of the chemical pathway involved during bitumen oxidation and various quantification techniques to measure the effect of aging. This review also highlights the potential use of antioxidants in bitumen and elaborates on the working mechanism of different types of antioxidants to prevent bitumen aging. Further, the effect of modification in bitumen at micro, macro, and mixture levels are discussed. Additionally, cost analysis and future prospects on the use of antioxidants for bitumen are presented.

Current situation, trend, and prospects of research on functional components from by-products of baijiu production: A review

In the present scenario marked by energy source shortages and escalating concerns regarding carbon dioxide emissions, there is a growing emphasis on the optimal utilization of biomass resources. Baijiu, as the Chinese national spirit, boasts remarkably high sales volumes annually. However, the production of baijiu yields various by-products, including solid residues (Jiuzao), liquid wastewater (Huangshui and waste alcohol), and gaseous waste. Recent years have witnessed dedicated research aimed at exploring the composition and potential applications of these by-products, seeking sustainable development and comprehensive resource utilization. This review systematically summarizes recent research, shedding light on both the baijiu brewing process and the bioactive compounds present baijiu production by-products (BPBPs). The primary focus lies in elucidating the potential extraction methods and applications of BPBPs, offering a practical approach to comprehensive utilization of by-products in functional food, medicine, cosmetic, and packaging fields. These applications not only contribute to enhancing production efficiency and mitigating environmental pollution, but also introduce innovative concepts for the sustainable advancement of associated industries. Future research avenues may include more in-depth compositional analysis, the development of utilization technologies, and the promotion of potential industrialization.

The mechanism of self-assembly of lignin in deep eutectic solvent based on sulfamic acid and urea through molecular dynamics simulation

Due to the diversity of industrial lignin sources and the complexity of its structure, its application as a high-value material is limited. Lignin nanoparticles (LNPs) have emerged as a hotspot for research due to their advantages of high specific surface area and high dispersion and the solvent transfer method is commonly used for the preparation of LNPs. In this paper, LNPs were prepared by solvent transfer method using DES based on sulfamic acid and urea (S/U DES) as solvent and water as anti-solvent. To explore the internal mechanism of the self-assembly of nanoparticles, a theoretical model of the solvent system and model lignin compound was constructed with the assistance of quantum chemistry and molecular dynamics theories. Through classical molecular dynamics (MD) simulations, the interaction energy, radius of gyration (ROG), solvent accessible surface area (SASS), radial and spatial distribution function (RDFs/SDFs), hydrogen bonding, and the morphology changes were analyzed to reveal the internal mechanism of self-assembly of model lignin compounds in S/U DES. This study is useful in revealing the mechanism of interaction between lignin and DES, as well as providing a benchmark for the green and efficient preparation of lignin nanoparticles.

Assessment of Quercetin Antiemetic Properties: In Vivo and In Silico Investigations on Receptor Binding Affinity and Synergistic Effects

Quercetin (QUA), a flavonoid compound, is ubiquitously found in plants and has demonstrated a diverse range of biological activities. The primary objective of the current study is to assess the potential antiemetic properties of QUA using an in vivo and in silico approach. In this experiment, 4-day-old chicks were purchased to induce emesis by orally administering copper sulfate pentahydrate (CuSO4·5H2O) at a dose of 50 mg/kg (orally). Domperidone (DOM) (6 mg/kg), Hyoscine (HYS) (21 mg/kg), and Ondansetron (OND) (5 mg/kg) were treated as positive controls (PCs), and distilled water and a trace amount of Tween 80 mixture was employed as a negative control (NC). QUA was given orally at two distinct doses (25 and 50 mg/kg). Additionally, QUA (50 mg/kg) and PCs were administered separately or in combination to assess their antagonistic or synergistic effects on the chicks. The binding affinity of QUA and referral ligands towards the serotonin receptor (5HT3), dopamine receptors (D2 and D3), and muscarinic acetylcholine receptors (M1-M5) were estimated, and ligand-receptor interactions were visualized through various computational tools. In vivo findings indicate that QUA (25 and 50 mg/kg) has a significant effect on reducing the number of retches (16.50 ± 4.65 and 10.00 ± 4.19 times) and increasing the chick latency period (59.25 ± 4.75 and 94.25 ± 4.01 s), respectively. Additionally, QUA (50 mg/kg) in combination with Domperidone and Ondansetron exhibited superior antiemetic effects, reducing the number of retches and increasing the onset of emesis-inducing time. Furthermore, it is worth noting that QUA exhibited the strongest binding affinity against the D2 receptor with a value of -9.7 kcal/mol through the formation of hydrogen and hydrophobic bonds. In summary, the study found that QUA exhibited antiemetic activity in chicks, potentially by interacting with the D2 receptor pathway.

Assessing the impact of ultra-thin diamond nanothreads on the glass transition temperature of a bituminous binder

Low-temperature cracking and rutting are the most destructive problems of bitumen that hinder the application of high-performance bitumen engineering, which is dependent on its glass transition temperature (Tg). Through in silico studies, this work has systematically investigated the Tg of a bituminous binder with the addition of diamond nanothread (DNT) fillers with varying filler content, alignment, distribution, and functional groups. In general, the glass transition phenomenon of the bitumen is determined by the mobility of its constituent molecules. Tg is found to increase gradually with the increase in the weight percentage of DNT and then decreases when the weight percentage exceeds 5.05 wt%. The enhancement effect on Tg is weakened when DNTs are distributed vertically or functionalized with functional groups. Specifically, DNT fillers induce inhomogeneity, which promotes the motion of small molecules while hindering the motion of large molecules. The aggregation of DNTs and the molecular environment in the vicinity of DNTs directly affect Tg. In summary, aggregation and adhesion are the dominant mechanisms affecting the mobility of the constituent molecules in the DNT/bitumen system and thus its glass transition temperature. This work provides in-depth insights into the underlying mechanisms for the glass transition of a bituminous binder, which could serve as theoretical guidance for tuning the low-temperature performance of the bituminous binder.

Double Effects of Oxidative Aging on Carbon Nanotube-Asphalt Nanocomposite Interfaces: Enhancement and Deterioration

Understanding the mechanisms of oxidative aging effects on the carbon nanotube (CNT)-asphalt nanocomposite interface has long been a challenge, as there are two opposing effects: enhancement and deterioration. In this study, a multiscale coupling method is proposed to analyze the dual effect of oxidative aging on the CNT-asphalt nanocomposite. The method is based on density functional theory (DFT) and molecular dynamics (MD) simulations, supported by microscopic interface observation and macroscopic property testing with a focus on the composite interface. The results show that oxidative aging has a resetting effect on benzene ring stacking at the interface and enhances the binding energy of CNT-asphalt. Meanwhile, oxidative aging enhanced the interfacial charge transfer, but no chemical reaction occurred between CNT-aged asphalt. This is also verified by Fourier Transform Infrared Spectroscopy (FTIR). Enhancement and degeneration effects of oxidative aging occur via distinct mechanisms. Oxidative aging enhanced the interfacial shear barrier by approximately 5% and the energy barrier by 44.87%, which increased the high-temperature deformation resistance of the CNT-asphalt nanocomposites. However, molecular oxidation was not responsible for the decline in the fatigue resistance. According to scanning electron microscopy (SEM) and atomic force microscopy (AFM) results, oxidative aging elevates the content of polar molecules, leading to an increase in the solid properties of asphalt and a 39.6% decrease in surface adhesion. This disrupts the three-dimensional network of the CNT and ultimately leads to a reduction in crack resistance. This study clarifies the mechanism underlying the dual effect of oxidative aging and provides fundamental support for understanding asphalt aging behavior and the interfacial behavior of composites.