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Zhuying Zhang,1,2,* Mai Shi,1,2,* Jinghui Li,3 Dian Chen,1,2 Jie Ren,1,2 Zhenghui Li,1,2 Hsiaohan Tuan,1,2,* Yi Zhao1,2,* 1Department of Dermatology, Beijing Tsinghua Changgung Hospital, Beijing, People’s Republic of China; 2Photomedicine Laboratory, Institute of Precision Medicine, Tsinghua University, Beijing, People’s Republic of China; 3School of Medicine, Tsinghua University, Beijing, People’s Republic of China*These authors contributed equally to this workCorrespondence: Yi Zhao; Hsiaohan Tuan, Department of Dermatology, Beijing Tsinghua Changgung Hospital, No. 168 Litang Road, Changping District, Beijing, 102218, People’s Republic of China, Tel +86-13718646181 ; +86-18610015166, Email zhaoyimd@tsinghua.edu.cn; dxha00337@btch.edu.cnIntroduction: The aging of the skin, which is affected by both external and internal causes, can reflect the external age and the internal health status. While the aging characteristics differ across ethnic groups, the specific changes in skin aging within the Chinese population have been underexplored. Moreover, investigating the similarity of aging skin characteristics between parent-offspring pairs remains uncharted territory. This study aims to fill these gaps by examining the skin aging features of Chinese women and assessing the similarity in aging skin characteristics between mother-daughter pairs.Methods: A total of 40 mother-daughter pairs were recruited and analyzed. The perceived ages of the participants were evaluated, and their aging skin traits were systematically graded. Statistical methods were employed to discern the trends of the aging skin characteristics. By introducing a novel similarity parameter, we compared whether various skin aging characteristics have similar patterns between mothers and daughters.Results: Our findings indicate that age 50 represents a pivotal point in skin aging. Beyond this age, the increase in rhytides and laxity scores accelerated noticeably, whereas the escalation in dyschromia scores became less marked. By introducing similar parameters between mother-daughter pairs and the radar map, we discovered that the skin aging characteristics are remarkably consistent between mother-daughter pairs.Conclusion: Understanding the main aging skin characteristics of different age groups can allow caregivers to devise treatments for preventing skin aging in women of various ages. The mother’s skin aging trend is also significant for the daughter’s skin aging prevention.Plain Language Summary: Skin aging, a complex process influenced by both internal and external factors, exhibits distinct patterns across ethnic groups. Despite this, the specific aging characteristics within the Chinese population and the hereditary similarities between parents and offspring have not been thoroughly investigated. To address this gap, our study focused on the skin aging features of Chinese women and explored the resemblance in these features between mother-daughter pairs. Eighty-seven women from the same community, including 40 mother-daughter pairs, participated in our study. We assessed how old each participant appeared to be and methodically evaluated their skin aging signs by a modified scale. With the introduction of a new similarity parameter, we further examined the extent to which skin aging traits showed parallel trends between mothers and their daughters.Our findings pinpoint age 50 as a pivotal moment in the skin aging trajectory, where the increase in wrinkles and skin laxity becomes more pronounced, contrasting with a deceleration in skin discoloration. Remarkably, a consistent pattern of aging characteristics was observed between mother-daughter pairs, suggesting a potential genetic influence. This study not only sheds light on the specific skin aging patterns among Chinese women but also underscores the significance of genetic factors in shaping these patterns. The insights gained pave the way for developing targeted interventions for skin aging prevention and treatment, emphasizing the importance of considering familial aging trends.Keywords: Chinese female, skin aging pattern, aging characteristics, intergenerational analysis

The characteristics of solid surfaces are studied in this paper. Different from the local roughness method, the fractal index-surface roughness space method is proposed in this paper. Based on this method, the morphological characteristics of rubber solid surfaces are analyzed, and the theoretical leakage probability of the seals made of the corresponding rubber materials is given. [ABSTRACT FROM AUTHOR]

Objective： This study aimed to develop a new type of sponge cake with glutinous rice flavor. Methods： To investigate the impact of different glutinous rice flour substitutions in the prepared baking flour on the rheological properties, density of batter, specific volume, baking loss rate, sensory evaluation and pore size distribution of cake were investigated. Also, the texture analysis, moisture distribution, starch ordered structure and crystallinity of cake after 7 days of storage were meaured. Results： With the increasing substitution of glutinous rice flour, the batter density reduced, improving the specific volume and the pore size distribution. Effectively delaying the retrogradation of cake is possible with high glutinous rice flour substitution (75%~100%). When the glutinous rice flour mass fraction is 75%, the cake tastes best and has the best degree of general preference. Conclusion： The mass fraction of glutinous rice flour 75%~100% is more suitable, and the addition of glutinous rice flour gives better quality to sponge cake, which can have important guiding significance for the development of pure glutinous rice flour gluten-free products.

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Food & Machinery is the property of Food & Machinery Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aging characteristics of Al/UHSS resistance rivet welding (RRW) joints are investigated for the first time in this paper. Microstructure studies have shown that the aging treatment does not change the phase composition of the Al/steel mixed nugget still remaining the ferrite structure, while the precipitation, growth and dissolution occur for the microstructure of Al alloy varying with the distance from the rivet. Mechanical tests revealed that for interfacial fracture (IF) and button pullout fracture (BPF) joints, the maximum peak load increased by 13% and 26% with the prolonged aging time, respectively. The improvement in the joint strength after aging can be attributed to the relaxation of the residual stress for IF joint and the age hardening of Al sheet for BPF joint. In addition, interestingly, the accelerated artificial aging is discovered firstly in Al/steel RRW joint. The phenomenon can be attributed to the higher solid solubility of Mg and Si in softening zone of Al sheet, resulting in faster and more precipitation during the aging treatment. The precipitation kinetics indicated that the average Avrami exponent was 1.25, proving the one-dimensional linear growth of fresh nuclei of the hardening phase β''. The block shear model analysis suggested that the Canadian Standards Association, giving the calculating/test values ratio ranged from 0.88 to 1.08, could provide a more reasonable calculation, which showed that the shear failure was mainly determined by the yield of the gross shear plane, and the tension plane failed because of tensile rupture during the lap-shear test.

The condition and health of large oil-immersed power transformers' insulation have a direct impact on the safety and stability of the power grid. Therefore, it is crucial to investigate the aging characteristics of oil–paper insulation in power transformers. In this study, we developed a computational model for reclosing current calculation and multiphysics coupling models for magnetic-circuit-force, electrostatic field, and temperature field simulations. The calculated aging resulted in a mechanical stress of 8.71 MPa, an electric field strength of 2.26 × 106 V/m, and a temperature of 113.7 °C. We conducted combined electrical–thermal–mechanical aging tests on the oil–paper insulation and measured various insulating paper performance parameters at different aging stages. Our study revealed that both the mechanical and electrical properties of the insulating paper deteriorated in both aging groups. However, the changes were more pronounced in the electrical–thermal–mechanical aging group compared to the electrical–thermal aging group, indicating that mechanical stress accelerated the aging process of the insulating paper. In the early stages of aging, the rate of performance changes in the electrical–thermal aging group was similar to that in the electrical–thermal–mechanical aging group. However, as the aging time increased, the degradation of performance induced by mechanical aging became more significant. This suggests that the insulating paper's resistance to mechanical damage, specifically short-circuit resistance, noticeably decreased after prolonged aging. [ABSTRACT FROM AUTHOR]

Copyright of Plastics Science & Technology / Suliao Ke-Ji is the property of Plastics Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, the aging process of composite insulator silicone rubber in a mountainous region environment was studied and a lifespan prediction model was constructed. Silicone rubber samples with various exposure times were analyzed based on the microstructure, physical properties, functional groups, and chemical environment of silicon. All experimental results corresponded to three aging stages: platform stage, upturn stage, and acceleration stage. Based on linear regression method, the peak content of Si(-O)2 and shore hardness A were selected to establish the lifespan prediction model for silicone rubber. Verification of the model showed that the residual lifespan error is less than 1.5 years. This study is based on a systematic analysis of three stages of the aging process for silicone rubber in composite insulators and obtaining critical aging parameters. Furthermore, a lifespan prediction model is proposed and validated.

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The condition and health of large oil-immersed power transformers’ insulation have a direct impact on the safety and stability of the power grid. Therefore, it is crucial to investigate the aging characteristics of oil–paper insulation in power transformers. In this study, we developed a computational model for reclosing current calculation and multiphysics coupling models for magnetic-circuit-force, electrostatic field, and temperature field simulations. The calculated aging resulted in a mechanical stress of 8.71 MPa, an electric field strength of 2.26 × 106 V/m, and a temperature of 113.7 °C. We conducted combined electrical–thermal–mechanical aging tests on the oil–paper insulation and measured various insulating paper performance parameters at different aging stages. Our study revealed that both the mechanical and electrical properties of the insulating paper deteriorated in both aging groups. However, the changes were more pronounced in the electrical–thermal–mechanical aging group compared to the electrical–thermal aging group, indicating that mechanical stress accelerated the aging process of the insulating paper. In the early stages of aging, the rate of performance changes in the electrical–thermal aging group was similar to that in the electrical–thermal–mechanical aging group. However, as the aging time increased, the degradation of performance induced by mechanical aging became more significant. This suggests that the insulating paper’s resistance to mechanical damage, specifically short-circuit resistance, noticeably decreased after prolonged aging.

The significant market growth of stationary electrical energy storage systems both for private and commercial applications has raised the question of battery lifetime under practical operation conditions. Here, we present a study of two 8 kWh lithium-ion battery (LIB) systems, each equipped with 14 lithium iron phosphate/graphite (LFP) single cells in different cell configurations. One system was based on a standard configuration with cells connected in series, including a cell-balancing system and a 48 V inverter. The other system featured a novel configuration of two stacks with a parallel connection of seven cells each, no cell-balancing system, and a 4 V inverter. The two systems were operated as part of a microgrid both in continuous cycling mode between 30% and 100% state of charge, and in solar-storage mode with day–night cycling. The aging characteristics in terms of capacity loss and internal resistance change in the cells were determined by disassembling the systems for regular checkups and characterizing the individual cells under well-defined laboratory conditions. As a main result, the two systems showed cell-averaged capacity losses of 18.6% and 21.4% for the serial and parallel configurations, respectively, after 2.5 years of operation with 810 (serial operation) and 881 (parallel operation) cumulated equivalent full cycles. This is significantly higher than the aging of a reference single cell cycled under laboratory conditions at 20 °C, which showed a capacity loss of only 10% after 1000 continuous full cycles. [ABSTRACT FROM AUTHOR]

Generally, PV (photovoltaic) modules are known as devices which are used semi-permanently for more than 20 years, but the electrical performance and lifespan of PV modules can be significantly degraded due to various environmental factors. Thus, a proper evaluation method for aging phenomenon of PV modules is required. Although there already are methods which compare adjusted PV output power based on STC (standard test condition) with initial PV module specification, or perform direct comparison by conducting the test under STC, there are issues with objectivity or efficiency in the existing evaluation method of aging phenomenon due to the data distortion while adjusting measured data or difficulties in implementation. Therefore, in order to overcome the above-mentioned disadvantage of the existing evaluation method for deterioration in PV modules and evaluate the aging characteristics of PV modules based on on-site measurement data in an accurate and efficient manner, this paper implements a test device for aging diagnosis to measure and collect actual data from a PV module section, and presents a modeling of data analysis for aging phenomenon with MATLAB S/W in order to minimize the variability of PV output, communication error, delay, etc. Furthermore, this paper confirms the usefulness of the presented test device for aging diagnosis of the PV modules which is accurately evaluated by considering on-site measurement of PV output power by season. [ABSTRACT FROM AUTHOR]

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to study the aging characteristics of SBS modified asphalt, firstly, the SBS modifier was simulated under hot oxygen and vacuum heating conditions, and the macro and microstructure changes of SBS under different aging conditions were analyzed・ Then, three indicators and multiple stresses were passed ・ Creep recovery test (MSCR) and infrared spectroscopy analyze the aging characteristics of SBS modified asphalt. The results show that: compared with vacuum heating, the SBS after thermal oxidative aging undergoes severe cross-linking reaction and loses 让s original elasticity and toughness; at the same time, the modified asphalt prepared from it also exhibits agglomeration of modifier particles, and the high and low temperature performance has decreased; from the change of functional groups, it can be seen that the carbon element in the asphalt and the C =C bond of the butadiene in the SBS modifier react with oxygen to form ketones and aldehydes containing carbonyl groups substance・ In summary, thermal oxidative aging will cause degradation of SBS modifiers and loss of characteristics, and at the same time cause oxidative hardening of the base asphalt, which will affect the performance of SBS modified asphalt. [ABSTRACT FROM AUTHOR]

The significant market growth of stationary electrical energy storage systems both for private and commercial applications has raised the question of battery lifetime under practical operation conditions. Here, we present a study of two 8 kWh lithium-ion battery (LIB) systems, each equipped with 14 lithium iron phosphate/graphite (LFP) single cells in different cell configurations. One system was based on a standard configuration with cells connected in series, including a cell-balancing system and a 48 V inverter. The other system featured a novel configuration of two stacks with a parallel connection of seven cells each, no cell-balancing system, and a 4 V inverter. The two systems were operated as part of a microgrid both in continuous cycling mode between 30% and 100% state of charge, and in solar-storage mode with day–night cycling. The aging characteristics in terms of capacity loss and internal resistance change in the cells were determined by disassembling the systems for regular checkups and characterizing the individual cells under well-defined laboratory conditions. As a main result, the two systems showed cell-averaged capacity losses of 18.6% and 21.4% for the serial and parallel configurations, respectively, after 2.5 years of operation with 810 (serial operation) and 881 (parallel operation) cumulated equivalent full cycles. This is significantly higher than the aging of a reference single cell cycled under laboratory conditions at 20 °C, which showed a capacity loss of only 10% after 1000 continuous full cycles.

Generally, PV (photovoltaic) modules are known as devices which are used semi-permanently for more than 20 years, but the electrical performance and lifespan of PV modules can be significantly degraded due to various environmental factors. Thus, a proper evaluation method for aging phenomenon of PV modules is required. Although there already are methods which compare adjusted PV output power based on STC (standard test condition) with initial PV module specification, or perform direct comparison by conducting the test under STC, there are issues with objectivity or efficiency in the existing evaluation method of aging phenomenon due to the data distortion while adjusting measured data or difficulties in implementation. Therefore, in order to overcome the above-mentioned disadvantage of the existing evaluation method for deterioration in PV modules and evaluate the aging characteristics of PV modules based on on-site measurement data in an accurate and efficient manner, this paper implements a test device for aging diagnosis to measure and collect actual data from a PV module section, and presents a modeling of data analysis for aging phenomenon with MATLAB S/W in order to minimize the variability of PV output, communication error, delay, etc. Furthermore, this paper confirms the usefulness of the presented test device for aging diagnosis of the PV modules which is accurately evaluated by considering on-site measurement of PV output power by season.

Multiple environmental stresses produce complex phenomena of aging in polymeric insulators. The main aim of this research is to investigate the improved aging characteristics of silica (SiO2)/alumina trihydrate (ATH) hybrid samples (HSs) in high-temperature vulcanized rubber. For this purpose, three HSs comprising 20% micro-ATH with 2% nano-SiO2 (S2), 4% nano-SiO2 (S4), 6% nano-SiO2 (S6) along with sample-virgin (SV) are subjected to long-term accelerated aging of 9000 h. A special aging chamber is fabricated for the aging process of samples. The aging characteristics of these samples are investigated by measuring leakage current (LC) and hydrophobicity classification (HC) after every weathering cycle. Similarly, Fourier transform infrared (FTIR) spectroscopy is performed to observe the important structural changes over the entire aging time. The dielectric strength of AC is also performed after every 1000 h of aging. Tracking and erosion resistance and mechanical properties are also investigated before and after aging. From the critical investigation, it is observed that HSs possess improved results in all the conducted tests. S2 has the lowest LC and HC values throughout the aging time. Similarly, S6 described the highest breakdown strength at the end of the accelerated aging. In the case of FTIR, it is analyzed that the important wave numbers remain intact for all the HSs in the accelerated aging environment. The loss percentage in the wave number for SV is higher, compared to the HSs. After performing the tracking and erosion resistance test, HSs have superior performance. For some of the mechanical properties, HSs showed improved values. Thus, from the experimental analysis, it is deducted that the sample S2 offers the highest resistance to the aging conditions, compared to the SV and other HSs. [ABSTRACT FROM AUTHOR]

Acidic fluids will cause rock erosion and further endanger the safety of rock engineering. To explore the aging characteristics of the mechanical damage under acid condition, diorite specimens were saturated in neutral water and acid solutions with pH values of 3 and 5 for 49 days. The masses and sizes of the specimens and the pH values of the acidic solution were tracked and measured. Besides, the specimens before and after saturations were observed by an electron microscope scanner. Meanwhile, triaxial compression tests were carried out under neutral water, pH = 5 and pH = 3 hydrochloric acid solutions, respectively. The mass damage features and mechanical properties of diorite specimens saturated in solutions with different pH values were analyzed. The results show: 1) after acidic saturation, the original lamellar structures and crystal forms were spongy or flocculent. The structure loosened and the boundary between layers became fuzzy. Meanwhile, the number of micro-cracks and micro-pores increased, which weakened the macro-mechanical performances of diorite; 2) the acid condition with pH value of 3 could be used to simulate the long-term effect of the weakly acidic environment in nature; 3) internal friction angle of diorite was more sensitive to acidic solutions than its cohesion; 4) at the initial stage of saturation, diorite broke rapidly. With increasing saturation time, the damage rate slowed down and finally stabilized. The established damage strength model considering acidification could properly describe the test results.

Impedance characteristics of the floating capacitor in the submodule (SM) of a modular multilevel converter (MMC) change due to its chemical and aging characteristics. This can result in a rise of voltage ripple across SM capacitors, uneven power distribution among the SMs and could also interrupt the operation with prolonged use of degraded capacitors. Existing balancing approaches are presented for the MMC with equal SM capacitance and ignored the effect of capacitor degradation as well as parameter mismatch. Hence, a closed‐loop control scheme that incorporates the effect of capacitor degradation is much necessitated. This study aims to overcome this gap by proposing a new power balancing control algorithm for SM capacitors, which effectively controls and evenly distributes the power among SMs. The efficacy of the proposed strategy is substantiated through PLECS simulations and OPAL‐RT/OP4510 controller‐based experiments on a single‐phase MMC laboratory prototype. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Agricultural plastic mulch is a major microplastics (MPs) source in terrestrial ecosystems. However, knowledge about the aging characteristics of mulch-derived MPs entering natural and agricultural soils and their effects on phthalate esters (PAEs) and organic carbon fractions is still limited. Black (contains black masterbatches) and white polyethylene (PE) and biodegradable (Bio, Poly propylene carbonate and Polybutylene adipate terephthalate synthetic material (PPC+PBAT)) mulch-derived MPs, at 0.3% (w/w) dose, were added to grassland and farmland soils for eight-week incubation. Microplastic (MP) aging degree was explored by quantifying the carbonyl index (CI). The soil PAEs and organic carbon fractions were also analyzed. After incubation, black and white PE-MP aged greater in farmland than in grassland. PAEs accumulated highest in PE-MP treatment (5.27–6.41 mg kg−1) followed by Bio-MP (1.88–2.38 mg kg−1). Soil organic carbon (SOC), particulate organic carbon (POC), and microbial biomass carbon (MBC) were reduced by 5.3%–8.2%, 31.8%–41.6%, and 39.7%–63.0%, dissolved organic carbon (DOC) was increased by 10.1%–27.6% in grassland containing MP compared to control. MPs' aging degree promoted PAEs content or altered nutrients, then regulated soil microbial biomass and extracellular enzyme activity directly or indirectly, ultimately affecting SOC. Microplastics are persistent environmental pollutants that gradually undergo surface aging in response to extracellular enzymes secreted by microorganisms. As microplastics age, their surface roughness and functional groups change; thus, organochemical contaminants gradually leach out. Therefore, this study analyzed the aging of mulch film-derived microplastics under the action of diverse microorganisms in farmland and grassland soils and the effect on plasticizer and organic carbon fractions. The results proved that polyethylene microplastic aging degree was highest in farmland soil. Besides, biodegradable microplastic caused lower contamination of phthalate esters than polyethylene, but they affected soil carbon balance in grassland and farmland soils. This study highlights that MPs affect organic carbon fractions by influencing the PAEs, available nutrients, and extracellular enzyme activity. [Display omitted] • Microbial diversity and microbes degrading polyethylene affect microplastic aging. • Microplastic aging increases soil phthalate esters and reduces microbial biomass. • Microplastic aging decreases organic carbon by affecting microbial biomass and enzyme. • Microplastic aging decreases particulate organic carbon content. [ABSTRACT FROM AUTHOR]

Freeze–thaw (F–T) cycling and aging effects are the main factors contributing to the deterioration of asphalt mixtures. The acoustic emission (AE) technique enables real-time detection regarding the evolution of internal damage in asphalt mixtures during the loading process. This study set out to investigate the effects of F–T cycling and aging on the damage characteristics of asphalt mixture under splitting loads. Firstly, the Marshall specimens were prepared and then exposed to various numbers of F–T cycles (one, three, five, and seven) and different durations of aging (short-term aging and long-term aging for 24, 72, 120 and 168 h), after which the specimens were loaded by means of indirect tensile (IDT) testing, and corresponding parameters were synchronously collected by the AE acquisition system during the fracture process. Finally, the energy, cumulative energy and peak frequency were selected to investigate the damage mechanisms of asphalt mixtures. The findings demonstrate that the AE parameters provided effective identification of the deterioration for all specimens in real-time, and that the F–T cycling and aging effects altered the damage characteristics of asphalt mixtures, causing early damage, exacerbating the formation of micro-cracks in the early stage, accelerating the expansion of macro-cracks and advancing the debonding between the asphalt and aggregates. The findings of this study provide further insight into the mechanism of F–T cycling and aging effects on the deterioration of asphalt mixture.

We describe here the aging characteristics and strengthening behavior of a low-carbon medium-Mn Cu precipitation-strengthened steel. Atom probe tomography (APT) was employed to characterize the evolution of Cu-rich precipitates in terms of mean radius, number density and volume fraction. Aging at 500 °C and 550 °C for 1 h resulted in substantial coherent body-centered cubic (bcc) Cu-rich precipitates with mean radius of 1.35 and 2.59 nm, respectively. The precipitation strengthening mechanism for these two aging conditions was shearing mechanism and the corresponding strengthening contribution was ~ 266 and ~ 312 MPa, respectively. Here, coherency strengthening and modulus strengthening played a major role, while the contribution of chemical strengthening was relatively small. With increased aging temperature to 600 °C, the precipitates grew and coarsened to elongated shape with incoherent face-centered cubic (fcc) structure, and the strengthening mechanism was Orowan mechanism with a contribution of ~ 232 MPa. Increasing the aging temperature also facilitated the formation of retained austenite, which was of great benefit to plasticity without pronounced deterioration on precipitation strengthening. Ultra-high yield strength of 1020 MPa with superior total elongation of 25.8% was obtained in the sample aged at 600 °C for 1 h. The excellent mechanical properties derived from the combination of precipitation strengthening by Cu-rich precipitates and plasticity effect of retained austenite can be considered as a design principle to simultaneously optimize strength and ductility. [ABSTRACT FROM AUTHOR]

This paper deals with a major effect of ytterbium on microstructure, electrical and dielectric properties, and aging characteristics of ZVM (ZnO–V2O5–Mn3O4) system. With the amount of the ytterbium increased, the average grain size decreased from 7.2 to 5.9 µm, whereas the density of the sintered pellets increased from 5.39 to 5.55 g/cm3. The breakdown field increased from 922 to 3774 V/cm with the increase of the amount of the ytterbium. The nonlinear coefficient exhibited a maximum value (29.2) at 0.025 mol% and a minimum value (5.7) at 0.25 mol% in the amount of the ytterbium. The sample added with 0.1 mol% Yb2O3 exhibited the highest stability; variation rates for the breakdown field and the nonlinear coefficient were 0.7% and − 4.2%, respectively, after application of a stress of 0.85 EB/85 °C/24 h. [ABSTRACT FROM AUTHOR]

The aging of bitumen seriously affects the service life of bituminous pavements. At present, there are many related researches on bitumen aging, but most of them focus on aging endured in indoor surroundings and conditions. Therefore, the conclusions obtained cannot reflect the actual aging changes of bitumen in bituminous pavements in service. In order to study the comprehensive aging process and mechanism of bitumen under the influence of service, we studied bridge deck, traffic lane, and ramp with bituminous pavement structures in service. The bitumen samples obtained from the core samples in different bituminous pavement structures were characterized by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), dynamic shear rheometer (DSR), and fluorescence microscope (FM). The aging degree of different bitumen was analyzed, and conclusions were drawn on changes to bitumen aging from different pavement structures. The results showed that the aging degree of bitumen from the upper layer was the most serious, the aging degree of bitumen at the middle layer was weaker than that of bitumen from the upper layer, and the aging degree of bitumen from the bottom layer was the weakest for the different bituminous pavement structures. The aging of bitumen mainly occurred due to oxygen absorption. After aging, viscoelastic components of bitumen changed, and bitumen became harder. The macromolecule of bitumen could be divided into small molecules, and the small molecular weight of bitumen became large. The styrene-butadiene-styrene (SBS) modifier in the modified bitumen became granular after aging, and it appeared as a single phase in bitumen. The aging changes characterized by different analytical methods showed that the aging degree of bitumen from different layers of bituminous pavement structures in service was different. Effective measures should therefore be taken in time to decrease further aging of bitumen from the upper layer of bituminous pavements due to its inevitable early aging in service.

Two kinds of rubber modified asphalts were investigated and compared with virgin asphalt. In order to get closer to engineering practice, different combinations of four environmental factors were merged into the laboratory aging simulation. Subsequently, conventional property tests, including softening point, viscosity, creep stiffness, creep rate, and fatigue cracking were conducted on asphalt samples. The performance difference of asphalt before and after aging was selected as an evaluation index for asphalt aging degree. The results indicate that two kinds of rubber modified asphalts show stronger resistant ability to temperature deformation and better resistance to traffic loading than virgin asphalt in all kinds of environmental factors combinations. Tests on chemical analyses were conducted to investigate the asphalt aging characteristics. The apparent morphology of rubber modified asphalts are described in detail under an environment scanning electron microscope (ESEM). The damage condition reflected in images reveals the aging degree caused by multiple environmental factors. Moreover, the thermogravimetric analysis (TG) confirms that three kinds of asphalts can maintain thermal stability in various environments. Additionally, new characteristic functional groups were not detected in the infrared (IR) spectra of rubber modified asphalts, which means they have stable antioxidant properties given that their oxidation degrees change slightly throughout the aging processes. [ABSTRACT FROM AUTHOR]

In this study, the aging process of composite insulator silicone rubber in a mountainous region environment was studied and a lifespan prediction model was constructed. Silicone rubber samples with various exposure times were analyzed based on the microstructure, physical properties, functional groups, and chemical environment of silicon. All experimental results corresponded to three aging stages: platform stage, upturn stage, and acceleration stage. Based on linear regression method, the peak content of Si(-O) 2 and shore hardness A were selected to establish the lifespan prediction model for silicone rubber. Verification of the model showed that the residual lifespan error is less than 1.5 years. This study is based on a systematic analysis of three stages of the aging process for silicone rubber in composite insulators and obtaining critical aging parameters. Furthermore, a lifespan prediction model is proposed and validated. • Platform, upturn, and acceleration stage are proposed corresponding to the evolution of microstructure and performances. • Shore hardness A and Si(-O) 2 relative content are employed as two non-correlated key parameters to judge the aging state. • Based on the multivariate stepwise regression analysis, the residual lifespan prediction model is established and verified. [ABSTRACT FROM AUTHOR]

Polyvinyl chloride (PVC) and polyvinylidene fluoride (PVDF) are membrane materials that are extensively used in the construction of large-span structures owing to their excellent performance and low cost. PVC and PVDF membranes are affected by their external environment during use, which causes aging and deterioration of their performance, thus reducing the service performance of the overall structure. Therefore, diverse mechanical properties, tests, elastic–plastic models, and aging mechanisms corresponding to natural and artificial aging (light-induced or high-temperature oxygen aging) are analyzed and compared herein to clarify the fundamental aging characteristics of PVC and PVDF membranes. The aging-related fundamentals of PVC and PVDF membranes are summarized, along with the associated problems. Additionally, suggestions for future studies on these membranes are presented. [ABSTRACT FROM AUTHOR]

A study involving two rolling-thin-film-oven-aged asphalts and their blends with 15 and 50% of extracted reclaimed asphalt pavement (RAP) binders was conducted to investigate the effect of RAP content and properties on the long-term aging characteristics of asphalt binders. The results from rheological analyses of aged, blended binders indicate that the aging characteristics of blended binders are dependent on fresh asphalt binders. The results show that the crossover frequency decreases at an exponential form as RAP concentrations increase, and the rheological index increases as RAP concentration increases. The pattern for stiffness increase as a function of aging times for RAP-blended binders is similar to that of a typical chemical-aging kinetic model, in which the stiffness increases substantially initially and then levels off at longer aging times. The results demonstrate that there is a linear relationship between the logarithm of and the phase angle for RAP-blended binders at all aging times and RAP contents, regardless of asphalt and RAP sources. [ABSTRACT FROM AUTHOR]

Abstract: Two types of tin oxide (SnO2) gas sensors were synthesized, which consist of spherical SnO2 nanoparticles and SnO2 nanorods mixed at different ratio, and their aging processes were studied. Using the Complex Impedance Spectroscopy method the electrical properties that are related to the microscopic structure of the samples were investigated. The evolution of absorption current was measured to analyze the ionic conductance that reflects the charging states of the samples. The results indicate that devices of optimal long-term stability can be obtained by sintering the mixture of SnO2 nanorods and spherical nanoparticles (1:1 weight ratio) at 850°C. In the samples’ impedance data considerable fluctuation could be seen during the early stage of the aging process, which gradually disappeared after several days. The aging process, which is revealed by the changes in both grain-boundary resistance and capacitance, indicates the corresponding changes in the grain-boundary barrier height and the width of depletion layer. We suggest the DC-field-induced migration of ions within the grain boundaries as the probable cause of the phenomenon. [Copyright &y& Elsevier]

Complex systems are usually repairable and subject to a few types of different preventive maintenance (including overhaul), which can be imperfect. This paper reanalyzes the bus-motor-failure data of [1]. Four different competing risk models, each of which has three parameters, are fitted to the data and the best model is identified. Based on an examination of the failure rate of the fitted model, two basic aging characteristics are identified and analyzed. The results are useful for modeling and analyzing similar systems. [ABSTRACT FROM AUTHOR]

The electrical properties and stability of the varistors, which composed of (NiO, MgO, Cr2O3)-doped Zn-Pr-Co-R (Y, Er) oxide-based ceramics, were investigated for different additives. The breakdown voltage of the varistors increased in order of NiO→undoped→MgO→Cr2O3: 1200→1551→1691→1959 V/cm for ZPCY system and undoped→NiO→MgO→Cr2O3: 1024→1041→1500→1668 V/cm for ZPCE system, respectively. The nonlinear coefficient value increased in order of undoped→NiO→MgO→Cr2O3: 21→ 25→38→50 in ZPCY system and NiO→undoped→MgO→Cr2O3: 27→32→35→38 in ZPCE system, respectively. In ZPCY and ZPCE systems, the Cr2O3-additives most greatly improved the nonlinear properties. In Cr2O3-doped system, ZPCY system exhibited higher nonlinear properties than that of ZPCE system. The stability against d.c. accelerated aging stress was higher in Cr2O3-additives than in NiO- and MgO-additives for ZPCY system and was higher in NiO-additives than in MgO- and Cr2O3-additives for ZPCE system. [ABSTRACT FROM AUTHOR]

Pb[(Zn 1/3 Nb 2/3 ) 0.91 Ti 0.09 ]O 3 single crystals with various crystal planes were evaluated regarding electromechanical coupling factor of k 31 mode and piezoelectric d 31 constant. Although these values depended on their crystal planes, the giant k 31 and d 31 were obtained in the case of the (100) crystal plane poled along [001] of the original cubic direction. The dielectric constant at room temperature increased with the time in the crystal of (110) plane, while the dielectric constants of the crystals with (100) and (111) planes were unchanged. The crystal plane dependence of ferroelectric properties and their aging characteristics could be explained by the relationships between the directions of the polarization axes and poling field. The bipolar pulse field dependence of k 31 and d 31 were also investigated in comparison with the DC poling field dependence. The giant k 31 and d 31 were obtained in the crystal of (100) plane by the bipolar pulse poling as well as by the DC poling. [ABSTRACT FROM AUTHOR]

Abstract: Relationships between surface state of indium tin oxide (ITO) and luminescent properties, and aging characteristics of organic light emitting diodes (OLEDs) were investigated. Polycrystalline ITO surface used as the substrate of the thin film OLED was changed by chemical etching and ultraviolet (UV) irradiation. Initial properties of luminescent characteristics showed no significant difference between different ITO surface states. On the other hand, the device fabricated on UV irradiated ITO showed longer lifetime than that of without UV irradiation. We found that UV irradiation was effective for the aging characteristics of thin film OLED. [Copyright &y& Elsevier]

We found the giant electromechanical coupling factor of k31 mode to be over 80% and the piezoelectric d31 constant to be nearly -1700 pC/N in ferroelectric single crystals of Pb[(Zn1/3Nb2/3)0.91 Ti0.09]O3 (PZNT91/09). The origin of the giant k31 was as follows: the crystal with multi-domains changed into one having a mono-domain in the direction perpendicular to the poling field (k31 mode) as well as in the direction parallel to the poling field. The discovery of the giant k31 found a key to clarify the origin of the high piezoelectricity in PZNT91/09. Investigating the crystal orientation dependence of k31 and their aging characteristics, the giant k31 and d31 accompanied with the superior aging characteristics could be obtained in the case of the rhombohedral (100) crystal poled along [001] of the original cubic direction. Furthermore, it is found that the Young's modulus Y (0.89×1010 N/m2) in rhombohedral PZNT91/09 with giant k31 is remarkably small. Therefore, we believe that the high piezoelectricity including the giant k31 in PZNT91/09 is due to the remarkable softness of the rhombohedral phase, not the existence of a M.P.B. for easy to deform symmetrically by poling field. [ABSTRACT FROM AUTHOR]

Freeze–thaw (F–T) cycling and aging effects are the main factors contributing to the deterioration of asphalt mixtures. The acoustic emission (AE) technique enables real-time detection regarding the evolution of internal damage in asphalt mixtures during the loading process. This study set out to investigate the effects of F–T cycling and aging on the damage characteristics of asphalt mixture under splitting loads. Firstly, the Marshall specimens were prepared and then exposed to various numbers of F–T cycles (one, three, five, and seven) and different durations of aging (short-term aging and long-term aging for 24, 72, 120 and 168 h), after which the specimens were loaded by means of indirect tensile (IDT) testing, and corresponding parameters were synchronously collected by the AE acquisition system during the fracture process. Finally, the energy, cumulative energy and peak frequency were selected to investigate the damage mechanisms of asphalt mixtures. The findings demonstrate that the AE parameters provided effective identification of the deterioration for all specimens in real-time, and that the F–T cycling and aging effects altered the damage characteristics of asphalt mixtures, causing early damage, exacerbating the formation of micro-cracks in the early stage, accelerating the expansion of macro-cracks and advancing the debonding between the asphalt and aggregates. The findings of this study provide further insight into the mechanism of F–T cycling and aging effects on the deterioration of asphalt mixture. [ABSTRACT FROM AUTHOR]

• The laser-textured silicone rubber surfaces have excellent anti-aging properties. • The surface with a distinct hierarchical structure has better anti-aging properties. • The laser-processed super-hydrophobic sample surface has self-healing performance. • Low-molecular migration induces self-healing of hydrophobic surface microstructure. The aging characteristics of laser-treated superhydrophobic silicone rubber surfaces was investigated through accelerated aging tests. It indicated that the superhydrophobic surfaces have excellent anti-aging properties, which is manifested in that even after aging for 1000 h, the contact angles of the superhydrophobic surfaces remain above 140o. The loss of hydrophobicity was caused by defects in the surface microstructures, a decrease in the hydrophobic ―CH 3 groups, and an increase in the hydrophilic ―OH groups on the surfaces. To avoid the decrease in the hydrophobicity of the prepared superhydrophobic surface, a simple and efficient heat treatment method was adopted to restore its hydrophobicity. After heat treatment at 200°C, the rolling angle of the aged surface was restored to 4.6o with a contact angle of 161.5o. This recovery is mainly attributed to the decrease in the content of the ―OH on the rubber surface during the heat treatment. The results also show the sample surface irradiated with a laser fluence of 10.0 J/cm2 has better anti-aging performance and self-healing properties due to the larger particles and a more distinct micro-nano hierarchical structures, providing a smaller actual illumination area and a larger heating area in the aging and heat treatment process. [ABSTRACT FROM AUTHOR]

VOCs are the key precursors of ozone and secondary organic aerosols. The results of source apportionment for VOCs are very important for the coordinated control of ozone and second organic particulate matter. However, VOCs do not fully meet the assumption of the receptor model because the VOCs released from each source are relatively unstable in the transmission process for their reactivity. As a result, we do not accurately obtain the actual source contribution when the receptor model is used for the source apportionment of VOCs. In order to solve the problem that the relative changes in the components caused by VOCs reactivity are not consistent with the PMF model hypothesis, the aging degree of VOCs was introduced to distinguish the state characteristics after their photochemical reactions in the ambient air. According to the ratio of ethylbenzene to m/p-xylene, VOCs monitored at Wuhai were divided into three aging states:high, medium, and low. The results showed that the model parameters, such as regression equation parameters (slope and intercept), standard error, determination coefficient, and pass rate of residual error, were improved obviously compared to the sample set after classification. Because the degree of aging is closely related to the transport time of air mass and the atmospheric oxidation in the atmosphere, it also reflects the different sources of air mass to some extent. In the high-aging VOCs samples, the coking source occupied a high proportion (up to 47.20%). In the low-aging VOCs samples, the combustion source and coking source accounted for a higher proportion, 28.67% and 24.39%, respectively. After the classification according to the aging degree, the results of VOCs source apportionment by PMF are more consistent with the actual contribution of emission sources.

A new facet passivation process especially for the realization of highly reliable 980-nm laser diodes (LD's) has been developed. This process includes 3 procedure steps which involve, in sequence: 1) ion irradiation; 2) interlayer deposition; and 3) ion-assisted deposition of coating material. We have named this passivation process “I-3.” We applied this I-3 passivation process to our planar type 980-nm LD's, which were cleaved in air, and compared the aging characteristics between conventionally coated devices and I-3 passivated ones. As a result of a preliminary reliability test, I-3 passivated devices with 200-250 mW output showed stable operation over 3000 h at 50°C. Moreover, a large scale reliability test is ongoing with 150-250 mW output powers and the results have shown no sudden failure during aging. This has meant a significant improvement of aging characteristics compared to conventional coating. In addition, we tried X-ray photo-electron spectroscopy (XPS) measurements to understand the physical phenomena associated with the I-3 process. A sample of air-exposed GaAs(110) substrate, corresponding to the facet, was found to have no GaOx and AsOx after I-3 processing at the interface. We attribute the improved aging characteristics to the excellent properties of the I-3 passivated facet despite the fact that it is cleaved in air. The I-3 process reduces nonradiative recombination that occurs due to excess and extrinsic surface states located at the facet caused by air exposure and resultant oxidation [ABSTRACT FROM PUBLISHER]