Rejuvenation Effects Research Articles

Modulating the rejuvenation in a Al75Mg25 metallic glass by multiple recovery annealing treatment

Rejuvenation presents a promising way to improve the plasticity of metallic glasses. How modulating the degree of rejuvenation of metallic glasses remains a challenging issue. Here, based on the molecular dynamics simulation, we investigate the evolution of the structural and mechanical properties of a binary Al75Mg25 metallic glass and successfully realized the rejuvenation modulation through the multiple recovery annealing treatment. A range of samples with different degrees of rejuvenation were obtained by successive multiple recovery annealing process. According to our calculations, we found that the degree of rejuvenation is highly correlated with the Al-centered clusters. Microstructural analyses show that a higher degree of rejuvenation is concomitant with less 1551 index of Honeycutt-Andersen indices and a lower content of <0,0,12,0 > in terms of Voronoi Tessellation analysis. Moreover, our calculated results demonstrate that the samples with the aging initial state show a higher degree of rejuvenation as compared to the samples with the rejuvenated initial state. This can be attributed to that there are more icosahedral clusters, which are more likely to change to other types of clusters with low local fivefold symmetry in the aged samples during the subsequent high-temperature annealing process. Our work confirms that proper multiple (no more than three times) recovery annealing treatment can increase the degree of rejuvenation of metallic glasses and can offer a better understanding of the effect of rejuvenation on the microstructures and mechanical properties of metallic glasses.

REGENERATION OF SECONDARY ASPHALT PAVEMENTS WITH REJUVENATING AGENTS

Recycling reclaimed asphalt pavement fulfills an important function in achieving a sustainable and environmentally friendly road construction industry. Using reclaimed asphalt pavement (RAP) it is possible to produce new asphalt with a small amount of virgin raw materials. This will reduce the amount of energy required to extract and process virgin asphalt pavement materials, along with the amount of waste generated during road reconstruction. Despite these advantages, road agencies have been reluctant to use high proportions of RAP materials in new asphalt production because the presence of large amounts of oxidized bitumen from RAP in new mixtures makes them less workable and less compactable than mixtures with virgin bitumen alone. One should also be aware of the high stiffness of RAP mixtures, which will make them difficult to use. Various methods can be used to overcome this problem, one of the most effective is the addition of rejuvenating agents. This article describes research into the production of asphalt mixtures from recycled asphalt pavement (RAP) material. This work aims to study the effectiveness of various rejuvenators for restoring the basic performance characteristics of asphalt pavements. The most effective rejuvenators and their classification are reviewed. The hypothesized mechanism of rejuvenation of asphalt pavements by the introduction of rejuvenators is presented. The methods of introducing various rejuvenators into RAP are described.

Enhancement of Facial Rejuvenation Through a Combination of 1565 nm Non-Ablative Fractional Laser with 30% Supramolecular Salicylic Acid.

The 1565 nm non-ablative fractional laser can effectively stimulate collagen regeneration, achieving the effect of skin rejuvenation and anti-aging. In recent years, it has been widely used in dermatology, especially in facial rejuvenation, treatment of stretch marks, and acne scar treatment, with significant results. However, after the 1565 nm non-ablative fractional laser treatment, patients may experience short-term erythema and edema. The inflammation after treatment may also cause pigmentation, making it difficult for some patients to accept. This article introduces a treatment method of 1565 nm non-ablative fractional laser combined with 30% super molecular salicylic acid for facial rejuvenation, effectively reducing posttreatment erythema and post-inflammatory pigmentation. The method includes specific treatment steps and the respective endpoint reactions of each step. The method starts by selecting appropriate energy parameters for the 1565 nm non-ablative fractional laser treatment, followed immediately by the application of 30% supramolecular salicylic acid. The treatment should be stopped when a frosty reaction occurs. The purpose of this project is to provide patients with a safer new method of facial rejuvenation treatment.

Radiofrequency Improves Facial Fine Lines by Thermal Effect: Damage or Just Stimulation?

Radiofrequency (RF) has been widely used for rejuvenation treatments, but without knowledge of the effective temperature of the target tissues or guidance on treatment parameters, it often leads to adverse reactions and pain. The aim of this study was to demonstrate that thermal stimulation can produce facial rejuvenation effects and to determine the optimal bipolar RF treatment parameters for treating facial fine lines. A bipolar RF device combined with CORE Technology was used in this study. Exvivo studies were conducted on both miniature swine and human skin, utilizing thermographic thermometry and histological analysis. Invivo swine studies were conducted using histological analysis and electron microscopy. A clinical trial was conducted, and the results were evaluated using the Alexiades Comprehensive Grading Scale (ACGS) and Global Aesthetic Improvement Scale (GAIS) scales. The bipolar RF technology can produce a significant effect by thermally stimulating collagen within just 2 weeks without causing thermal damage. A clinical trial involving 46 patients showed a noticeable rejuvenating effect of the bipolar RF device, especially on fine wrinkles. This study confirmed that thermal stimulation, rather than thermal damage, is sufficient to achieve rejuvenation effects. The study also found a range of bipolar RF treatment parameters that are both safe and effective for facial fine lines.

Efficacy and Safety of a Home-Use Light-Emitting Diode Neck Device for Improvement in Neck Wrinkles: A Multicenter, Randomized, Double-Blind, Sham Device, Superiority Verification, Confirmatory Clinical Trial.

Light-emitting diode (LED) light sources have become an increasingly popular choice for the treatment and rejuvenation of various dermatological conditions. This study aimed to evaluate the effects of neck rejuvenation, patient satisfaction, and the safety of LED application to the neck in an Asian population. This was a multicenter, randomized, double-blind, sham device study. Seventy participants were enrolled in the study. The participants wore the home-use LED neck device for 9 min a day, 5 times a week, for a total of 60 sessions. The Lemperle Wrinkle Scale (LWS) and Global Aesthetic Improvement Scale (GAIS) were used to evaluate the results of both investigators and participants. The thyroid gland was examined using ultrasonography to evaluate the safety of the investigational device. The percentage of participants with improved LWS at Week 12 was significantly higher in the study group. Additionally, the percentage of participants with improved LWS was significantly higher in the study group at Weeks 8, 12, and 16. The LWS at Week 12 corrected with baseline values was found to be significantly different between the two groups. GAIS showed significant differences at 8, 12, and 16 weeks in the investigators' evaluation but not in the participants' evaluation. Repeated-measures analysis of variance at Weeks 4, 8, 12, and 16 also confirmed a significant difference between the two groups only in investigator assessment. No significant thyroid-related complications were observed. LED application to the neck may be considered a satisfactory and safe procedure for neck rejuvenation.

Moisture damage mechanism of asphalt mixtures containing reclaimed asphalt pavement binder: A novel molecular dynamics study

Reclaimed asphalt pavement (RAP) stands at the forefront of sustainable practices in road construction and rehabilitation. However, concerns regarding the moisture susceptibility of aged RAP binder have arisen due to its potential hazard to pavement durability. So far, the underlying mechanisms of how moisture infiltrates into the mixture and results in binder stripping remain controversial and scarcely investigated. To address this challenge, a novel molecular dynamics (MD) simulation method has been developed to explore the nanoscale stripping mechanisms, considering the effects of asphalt oxidative aging and rejuvenation. The results indicate that hydrogen bonding interactions between water and the aggregate surface reduce the contact distance compared to the distance between asphalt and aggregate. Under pore water pressure, moisture diffuses into the interface, occupying the van der Waals adhesion sites of asphalt molecules and consequently causing detachment. Asphalt oxidative aging, on one hand, increases the oxygen concentration and hydrophilicity, thereby increasing moisture susceptibility from the energy perspective. On the other hand, it increases the intermolecular friction between aged asphalt molecules, leading to reduced flexibility and age hardening, consequently triggering asphalt premature detachment and diminishing its coating quality on the aggregate surface. Rejuvenators can restore the moisture sensitivity of severely aged asphalt, with a mechanism involving two aspects: firstly, reducing the agglomeration and proportion of polar components in asphalt, thereby weakening its hydrophilicity; secondly, lubricating aged asphalt molecules to restore their flexibility and surface coating properties. Findings from this study contribute to revealing the moisture-induced damage mechanism when recycling RAP binder.

Novel composite rejuvenators development and comparative analyses of epoxy versus diisocyanate rejuvenators in rejuvenating aged SBS-modified asphalt binders

Currently, many high-grade highways are undergoing expansion and remodeling phases. Utilizing recycled Styrene-Butadiene-Styrene (SBS) modified asphalt mixtures not only increases waste material utilization but also offers significant environmental benefits. In pursuit of high-quality rejuvenation of aged SBS-modified asphalt binders (SBSMA), this research leveraged aromatic oil (AO) as the component rejuvenator and introduced two novel SBS rejuvenators: ethylene glycol diglycidyl ether (GDE) and isophorone diisocyanate (IPDI). Furthermore, the study explores the mechanisms and effectiveness of both epoxy and diisocyanate rejuvenators, which are commonly used in SBS rejuvenation, specifically focusing on reconstructing cross-linked network structures within rejuvenated SBSMA. Findings indicate that during rejuvenation with diisocyanate rejuvenators and AO, the amide groups effectively react with carboxyl and ester groups in aged SBS, thus reconstructing the SBS modifiers. The rejuvenated SBS subsequently absorbs AO and light components, leading to swelling and the reconstruction of cross-linked network structures. Nevertheless, the rejuvenation efficacy of epoxy rejuvenators was relatively limited due to their low reactive nature or adverse side reactions that could degrade the rejuvenated SBS molecules, resulting in less effective reconstruction of the network structure. The specific differences in the reconstruction of network structures were reflected that diisocyanate rejuvenators improved the road performance of rejuvenated SBSMA under both high and low temperatures, reaching or even surpassing unaged SBSMA, while the performance of epoxy rejuvenators was closer to that achieved using AO alone. Overall, diisocyanate rejuvenators outperformed epoxy rejuvenators in repairing SBS, significantly enhancing the performance of SBSMA. This study provides valuable insights into achieving high-quality rejuvenation of SBSMA, which can significantly enhance the efficiency and quality of rejuvenation in high-grade roadways.

Using rheology to study the synergistic effect of anti-aging modifier and rejuvenator on aged asphalt binder

A composite anti-aging rejuvenator for road asphalt was studied and prepared. Asphalt samples with different aging degrees and modifier dosages were prepared by RTFOT(rolling thin film oven) and PAV(pressure aging vessle)， and the viscoelastic, high temperature, low temperature and fatigue properties of the modified asphalt were comprehensively characterised based on their rheological properties. The test results showed that the composite anti-aging rejuvenator improved the fatigue performance and low temperature performance of aging asphalt. Among them, the creep rate m value at −18°C was recovered to 99.2 % of the unaged level, and the G-R(Glover-Rowe) parameter was reduced to more than 90 %. After long term aging of the composite anti-aging reclaimed mixtures were still able to maintain the water stability and low temperature performance higher than the level required by the specification. The paper found the better effect of adding same ratio of rejuvenator and anti-aging agent to aging asphalt. The reason was that the same ratio of rejuvenator and anti-aging agent could have synergistic effect and enhance each other. This paper verified the road value of the composite anti-aging rejuvenator from asphalt and asphalt mixtures, which provides technical support and reference for the promotion of old pavement reclamation and long-life pavement.

Analysis of Rheological Properties and Regeneration Mechanism of Recycled Styrene-Butadiene-Styrene Block Copolymer (SBS) Modified Asphalt Binder Using Different Rejuvenators.

The regeneration performance of an aged styrene-butadiene-styrene block copolymer (SBS) will be significantly influenced by different rejuvenators. The objective of this study was to comparatively investigate the regeneration effect of different SBS-modified asphalt regenerators on aged SBS-modified asphalt. Four types of different regenerant formulations were selected. The optimal rejuvenator content was determined firstly using conventional performance tests. The rheological properties of the aged SBS-modified asphalt binder were evaluated by multiple stress creep recovery (MSCR) experiments. Subsequently, the regeneration mechanism of the SBS-modified asphalt binder was investigated using thin-layer chromatography-flame ionization detection (TLC-FID) and Fourier transform infrared spectroscopy (FTIR). The results showed that the rejuvenator had a certain recovery effect on the penetration, softening point, and ductility of the SBS-modified asphalt binder after aging. The SBS-modified rejuvenating agent was the most favorable among the four types of rejuvenators, where a rejuvenator dosage of 12% showed the optimal rejuvenation effect. The addition of regenerators could appropriately improve the elastic deformation capacity of the aged asphalt binder. The epoxy soybean oil in the regenerant reacted with the aging SBS-modified asphalt binder, supplementing the lost oil in the aged SBS-modified asphalt binder, dispersing the excessive accumulation of asphaltene, and making the residual SBS swell again. The viscoelastic properties of the aging asphalt binder were improved by adjusting the content of components and functional groups to achieve the purpose of regeneration.

Mechanism of Rejuvenation in Aged SBS-Modified Asphalt by Density Functional Theory

As a large area of SBS-modified asphalt pavement entered the maintenance period, the aging and rejuvenation of SBS-modified asphalt have attracted attention in recent years. In order to further study the rejuvenation of aged SBS-modified asphalt, both rheological experiments and quantum mechanical simulations were used. Complex shear modulus (G*) and phase angle (δ) were used to analyze the rejuvenation effect of aged SBS-modified asphalt. Electron density, binding energy (Ebinding), and charge transfer number (Qtransfer) were used to observe the process of rejuvenation in aged SBS-modified asphalt. The results show that compared to asphalt components, SBS polymer was the least stable and most susceptible to breaking. After oxidative aging, SBS polymer with its aging products could impair the rejuvenation in aged asphalt. The interaction between aromatic components in rejuvenator and asphaltenes in aged asphalt was unstable and could be influenced by asphalt aging level. The interaction between heavy component molecules in aged asphalt with saturate component molecules in rejuvenator are closer than those with aromatic components molecules. The binding energies between saturate components in rejuvenator and asphaltenes in aged asphalt could be served as an evaluation indicator of rejuvenation.

AI Prediction for Post-Lower Blepharoplasty Age Reduction.

Aesthetic standards vary and are subjective for each person, and artificial intelligence is booming in this era. the authors aim to provide a relatively objective assessment of the aesthetic outcomes, enhancing the decision-making process and understanding of the surgical results. 150 patients who had undergone lower blepharoplasty-related surgeries were included in our study. FaceAge software was created by our research team, which included four publicly age estimation convolution neural network (CNN) models, Amazon AWS Rekognition (Seattle, WA), Microsoft Azure Face (Redmond, WA), Face++ Detect (Beijing, China), and Inferdo face detection (New York, NY). We then first used this application for age accuracy between the real age and the age estimated by the four CNNs. Second, we used this application to estimate all the preoperative and postoperative images' age of 150 patients and evaluate the effort of lower blepharoplasty. In terms of accuracy in age prediction, all CNN models exhibited a certain degree of accuracy. For all 150 patients undergoing lower blepharoplasty-related surgeries, the surgeries' effect showed about 2 years of rejuvenation with a statistically significant difference; for the sex difference, men had more age reduction than women also with a statistically significant difference; quadrilateral blepharoplasty showed the most significant effect on anti-aging effect. By using the deep learning models, lower blepharoplasty-related surgeries actually had an effect on age reduction. The potential of deep learning models will provide quantitative evidence for the rejuvenation effects of blepharoplasty or other cosmetic surgeries.

Influence of bio-based and refined rejuvenators on asphalt mixture with cold RAP

ABSTRACT In the recent years, research on the effects of rejuvenation on hot mix asphalt (HMA) with a high amount of RAP (Reclaimed Asphalt Pavement) has intensified. However, the vast majority of scientists focus on the technology of preheated RAP addition (e.g. in the parallel dryer). It was decided to investigate the effect of rejuvenators on asphalt mixtures containing non-preheated RAP (RAP cold addition into the mixer). Different types of rejuvenators were used in the research. The tests were carried out for the binder course and the base course. The optimal amount of cold RAP in the mixtures was determined and based on the initial tests of stiffness modulus and air void content, the amount of rejuvenators was adjusted for later tests. Tests of air void content, stiffness, resistance to water and frost and rutting resistance were carried out in the laboratory. Afterwards tests in the asphalt mixing plant were conducted for the rejuvenator with the best results for the base course. The results obtained confirmed the potential of using rejuvenators for mixtures with cold RAP addition into the mixer. It has been shown that bio-based rejuvenators are suitable for the use in different types of asphalt mixtures.

Epistemic uncertainty challenges aging clock reliability in predicting rejuvenation effects.

Epigenetic aging clocks have been widely used to validate rejuvenation effects during cellular reprogramming. However, these predictions are unverifiable because the true biological age of reprogrammed cells remains unknown. We present an analytical framework to consider rejuvenation predictions from the uncertainty perspective. Our analysis reveals that the DNA methylation profiles across reprogramming are poorly represented in the aging data used to train clock models, thus introducing high epistemic uncertainty in age estimations. Moreover, predictions of different published clocks are inconsistent, with some even suggesting zero or negative rejuvenation. While not questioning the possibility of age reversal, we show that the high clock uncertainty challenges the reliability of rejuvenation effects observed during invitro reprogramming before pluripotency and throughout embryogenesis. Conversely, our method reveals a significant age increase after invivo reprogramming. We recommend including uncertainty estimation in future aging clock models to avoid the risk of misinterpreting the results of biological age prediction.

Spatiotemporal transcriptomic profiling and modeling of mouse brain at single-cell resolution reveals cell proximity effects of aging and rejuvenation.

Old age is associated with a decline in cognitive function and an increase in neurodegenerative disease risk1. Brain aging is complex and accompanied by many cellular changes2-20. However, the influence that aged cells have on neighboring cells and how this contributes to tissue decline is unknown. More generally, the tools to systematically address this question in aging tissues have not yet been developed. Here, we generate spatiotemporal data at single-cell resolution for the mouse brain across lifespan, and we develop the first machine learning models based on spatial transcriptomics ('spatial aging clocks') to reveal cell proximity effects during brain aging and rejuvenation. We collect a single-cell spatial transcriptomics brain atlas of 4.2 million cells from 20 distinct ages and across two rejuvenating interventions-exercise and partial reprogramming. We identify spatial and cell type-specific transcriptomic fingerprints of aging, rejuvenation, and disease, including for rare cell types. Using spatial aging clocks and deep learning models, we find that T cells, which infiltrate the brain with age, have a striking pro-aging proximity effect on neighboring cells. Surprisingly, neural stem cells have a strong pro-rejuvenating effect on neighboring cells. By developing computational tools to identify mediators of these proximity effects, we find that pro-aging T cells trigger a local inflammatory response likely via interferon-γ whereas pro-rejuvenating neural stem cells impact the metabolism of neighboring cells possibly via growth factors (e.g. vascular endothelial growth factor) and extracellular vesicles, and we experimentally validate some of these predictions. These results suggest that rare cells can have a drastic influence on their neighbors and could be targeted to counter tissue aging. We anticipate that these spatial aging clocks will not only allow scalable assessment of the efficacy of interventions for aging and disease but also represent a new tool for studying cell-cell interactions in many spatial contexts.

Performance Evaluation of Multiple Aging-Regeneration of SBS-Modified Bitumen Regenerated by a Composite Rejuvenator

In this study, compound regeneration of SBS-modified bitumen (SMB) was carried out by a composite rejuvenator composed of furfural extraction oil (FEO) and 1,6-hexanediol diglycidyl ether (HDDGE) in the presence of catalyst triethanolamine (TEOA). SMB was subjected to three aging-regeneration cycles, and the physical and rheological properties, toughness and tenacity, and chemical structures of the SMB after each aging-regeneration cycle were tested to investigate the regeneration effect of the composite rejuvenator on SMB at different numbers of cycles. The ductility decreases and low-temperature properties deteriorate as the number of cycles increased, but the high-temperature properties of the SMB are improved. The complex modulus aging index and phase angle aging index indicate that the viscous behavior of SMB weakens after the second and third aging. The degree of viscoelasticity and toughness recovery decreases with the increase in the number of cycles, and the tenacity of SMB after the third aging-regeneration cycle is basically lost. The results of the Fourier transform infrared (FTIR) spectra tests prove that with the increase in the aging–regeneration cycles of SMB, the intensity of FTIR peaks of oxygen-containing functional groups is greater, and the recovery of aged SMB is gradually weakened.

The Rejuvenation Effect of Bio-Oils on Long-Term Aged Asphalt.

Generally, rejuvenators are used to supply missing components of aged asphalt, reverse the aging process, and are widely used in asphalt maintenance and recycling. However, compared with traditional rejuvenators, bio-oil rejuvenators are environmentally friendly, economical and efficient. This study looks into the effect of the three different bio-oils, namely sunflower oil, soybean oil, and palm oil, on the physical properties, rheological properties and chemical components of aged asphalt at different dosages. The asphalt physical properties and Dynamic Shear Rheological (DSR) test results show that with the increase in bio-oil, the physical properties and rheological properties of rejuvenated asphalt are close to those of virgin asphalt, but the high-temperature rutting resistance needs to be further improved. The results of Fourier Transform Infrared Spectroscopy (FTIR) show that the carbonyl and sulfoxide indices of rejuvenated asphalt are much lower than those of aged asphalt. Moreover, the rejuvenation efficiency of aged asphalt mixed with sunflower oil is better than that with soybean oil and palm oil at the same dosage.

Hsa-miR-134-5p predicts cardiovascular risk in circulating mononuclear cells and improves angiogenic action of senescent endothelial progenitor cells.

This research explores the role of microRNA in senescence of human endothelial progenitor cells (EPCs) induced by replication. Hsa-miR-134-5p was found up-regulated in senescent EPCs where overexpression improved angiogenic activity. Hsa-miR-134-5p, which targeted transforming growth factor β-activated kinase 1-binding protein 1 (TAB1) gene, down-regulated TAB1 protein, and inhibited phosphorylation of p38 mitogen-activated protein kinase (p38) in hsa-miR-134-5p-overexpressed senescent EPCs. Treatment with siRNA specific to TAB1 (TAB1si) down-regulated TAB1 protein and subsequently inhibited p38 activation in senescent EPCs. Treatment with TAB1si and p38 inhibitor, respectively, showed angiogenic improvement. In parallel, transforming growth factor Beta 1 (TGF-β1) was down-regulated in hsa-miR-134-5p-overexpressed senescent EPCs and addition of TGF-β1 suppressed the angiogenic improvement. Analysis of peripheral blood mononuclear cells (PBMCs) disclosed expression levels of hsa-miR-134-5p altered in adult life, reaching a peak before 65 years, and then falling in advanced age. Calculation of the Framingham risk score showed the score inversely correlates with the hsa-miR-134-5p expression level. In summary, hsa-miR-134-5p is involved in the regulation of senescence-related change of angiogenic activity via TAB1-p38 signalling and via TGF-β1 reduction. Hsa-miR-134-5p has a potential cellular rejuvenation effect in human senescent EPCs. Detection of human PBMC-derived hsa-miR-134-5p predicts cardiovascular risk.

Long-term Freeze–thaw effect on fracture performance of asphalt mixture with reclaimed asphalt pavement, glass fiber and rejuvenator

This investigation explored the influence of reclaimed asphalt pavement (RAP), glass fiber, and rejuvenator on the fracture characteristics of hot mix asphalt (HMA) exposed to freeze–thaw (F–T) conditions. The simulation of long-term F–T action was executed by performing tests across up to 7 F–T cycles. Semi-circular bending (SCB) tests at −10 °C and 25 °C provided insights into the fracture behavior from low to intermediate temperatures. At −10 °C, the incorporation of 25% RAP initially elevated the stress intensity factor without F–T conditioning but adversely affected fracture performance upon sustained F–T exposure. A rejuvenator application resulted in a lower initial stress intensity factor yet improved fracture resistance against long-term F–T action. Conversely, at 25 °C, RAP presence promoted moisture damage accumulation throughout the F–T cycles. A judicious blend of glass fiber and rejuvenator augmented the magnitudes of the J-integral, indicative of better fracture resistance in light of F–T effects. In comparison to H-50R, both 0.05% glass fiber and rejuvenator independently contributed to an increase in fracture energies through all stages of F–T treatment. Nonetheless, their combined impact was more pronounced. The study comprehensively assessed the collective effects of RAP, glass fiber, and rejuvenator on the overall fracture performance, presenting findings that could inform the design of durable asphalt pavements capable of withstanding the rigors of extended F–T exposure.

Synergistic effects of epoxy polymer and rejuvenator in asphalt rejuvenation: A comprehensive performance analysis

Epoxy asphalt mixtures are renowned for their exceptional road performance. In this study, the simultaneous application of a rejuvenator and epoxy polymer in asphalt rejuvenation, comparing it with using only epoxy polymer were explored. Approaches were evaluated from the perspectives of tensile performance, low-temperature performance, viscosity properties, microscopic phase morphology, and molecular structure. Results reveal that the addition of the rejuvenator enhances the tensile toughness of the aged asphalt-epoxy system while significantly reducing viscosity under identical temperature and curing conditions. Microscopic analysis indicates that the rejuvenator weakens the uniformity of the dispersed phase, resulting in a less tightly interlocked structure between aged asphalt and the epoxy system. Molecular simulations demonstrate that the compatibility of aged asphalt with the rejuvenator and epoxy system is comparable to that of aged asphalt and the epoxy system alone. Furthermore, a small amount of rejuvenator increases the conversion degree of the epoxy system, whereas an excessive amount inhibits the curing reaction. These findings not only shed light on the mechanisms underlying rejuvenated epoxy asphalt systems but also hold promise for enhancing the competitiveness of such systems throughout their service life cycle.

Rejuvenation and memory effects in active glasses induced by thermal and active cycling

It has recently been shown that thermal active glasses can display physical aging behavior comparable to that of passive glasses, although there are some notable distinctions due to the intrinsic nonequilibrium nature of active matter. The question whether active disordered materials can also exhibit rejuvenation and memory effects, akin to the phenomenology of, e.g., spin glasses, has thus far remained unexplored. Here we address this question by numerical simulations of active glasses composed of active Brownian particles that are subjected to a thermal or active cycling protocol. We find that an active system undergoing thermal cycling indeed shows rejuvenation and memory effects, with the strength of rejuvenation depending on the persistence time. In contrast, however, a passive Brownian system subjected to the same thermal cycle lacks the rejuvenation effect. We attribute this to the enhanced motility of active particles, which enables them to escape from their cages and restart aging at the new temperature, thus rejuvenating the material. Finally, we also demonstrate that both rejuvenation and memory effects can be induced by an activity cycle which quenches the material from an active to passive glass and back, providing a unique means to rejuvenate active matter. Published by the American Physical Society 2024