Search results for: aging effect

Authors: Elizabeth A. Haruna, Bulus Kpame, Kankanala Venkateswarlu

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The interaction of health and athletic performance with biologic aging has been an interesting and intriguing area for research. There has been a general acknowledgement of its importance to major public health and elite performance outcomes. There are many questions unanswered about the mechanisms of effects and dose-response changes. An attempt has been made in this paper to highlight potentially positive effects of regular training on the aging process and its effects on health. Age associated decline in health and performance results from the combination of the aging process itself, inactive lifestyle and primary diseases. An attempt is made in this paper to critically review what is known and what is unknown about evidence based changes, common to disuse and aging. Mechanisms responsible for the slowing decline in muscle mass and muscle force (sarcopenia) down of age – associated, weakness and fatigability due to year round athletic training have been discussed. It is in this regard we have attempted to share our views on advances made so far in understanding the impact of aging on health. We also attempted to explain how the biological effects of aging are minimized during appropriate year round athletic training. On the basis of available research evidence it was concluded that exercise training significantly slow down the deleterious effects of aging on health.

Keywords: aging, atrophy, sarcopenia, plyometric training

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Authors: S. Redjala, N. Ait Hocine, M. Gratton, N. Poirot, R. Ferhoum, S. Azem

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Polycarbonate (PC) is a promising polymer with high transparency in the range of the visible spectrum and is used in various fields, for example medical, electronic, automotive. Its low weight, chemical inertia, high impact resistance and relatively low cost are of major importance. In recent decades, some materials such as metals and ceramics have been replaced by polymers because of their superior advantages. However, some characteristics of the polymers are highly modified under the effect of ultraviolet (UV) radiation and temperature. The changes induced in the material by such aging depend on the exposure time, the wavelength of the UV radiation and the temperature level. The UV energy is sufficient to break the chemical bonds leading to a cleavage of the molecular chains. This causes changes in the mechanical, thermal, optical and morphological properties of the material. The present work is focused on the study of the effects of aging under ultraviolet (UV) radiation and under different temperature values on the physical-chemical and mechanical properties of a PC. Thus, various investigations, such as FTIR and XRD analyses, SEM and optical microscopy observations, micro-hardness measurements and monotonic and cyclic tensile tests, were carried out on the PC in the initial state and after aging. Results have shown the impact of aging on the properties of the PC studied. In fact, the MEB highlighted changes in the superficial morphology of the material by the presence of cracks and material de-bonding in the form of debris. The FTIR spectra reveal an attenuation of the peaks like the hydroxyl (OH) groups located at 3520 cm-1. The XRD lines shift towards a larger angle, reaching a maximum of 3°. In addition, Vickers micro-hardness measurements show that aging affects the surface and the core of the material, which results in different mechanical behaviours under monotonic and cyclic tensile tests. This study pointed out effects of aging on the macroscopic properties of the PC studied, in relationship with its microstructural changes.

Keywords: mechanical properties, physical-chemical properties, polycarbonate, UV aging, temperature aging

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Authors: Lisa Handwerker

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Using a Medical Anthropological lens, the paper will explore ideas elated to "aging in place" among Northern Californian older adults. Older adults seek independence, autonomy, flexibility, engagement, fulfillment and community in their pursuit of the highest quality of life. These values are at the heart of healthy and active "aging in place'. Drawing on a case study, the paper will examine one membership based non-profit organization for older adults united by the members' desire to be healthy and active while remaining in their homes for as long as possible. Relying on both volunteer and paid work, the paper explores the use of volunteer peer-to peer support, community building and advanced technologies toward this goal.

Keywords: aging in place, healthy and active aging, northern california, medical anthropologist, engagement, autonomy, flexibility, community, volunteers, quality of life

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Authors: Rachid El Aidani, Phuong Nguyen-Tri, Toan Vu-Khanh

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The filter media in synthetic fibre is the most geotextile materials used in aerosol and drainage filtration, particularly for buildings soil reinforcement in civil engineering due to its appropriated properties and its low cost. However, the current understanding of the durability and stability of this material in real service conditions, especially under severe long-term conditions are completely limited. This study has examined the effects of the chemical aging of a filter media in polyester nonwoven under different temperatures (50, 70 and 80˚C) and pH (2. 7 and 12). The effect of aging conditions on mechanical properties, morphology, permeability, thermal stability and molar weigh changes is investigated. The results showed a significant reduction of mechanical properties in term of tensile strength, puncture force and tearing forces of the filter media after chemical aging due to the chemical degradation. The molar mass and mechanical properties changes in different temperature and pH showed a complex dependence of material properties on environmental conditions. The SEM and AFM characterizations showed a significant impact of the thermal aging on the morphological properties of the fibres. Based on the obtained results, the lifetime of the material in different temperatures was determined by the use of the Arrhenius model. These results provide useful information to better understand phenomena occurring during chemical aging of the filter media and may help to predict the service lifetime of this material in real used conditions.

Keywords: nonwoven membrane, chemical aging, mechanical properties, lifetime, filter media

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Authors: Nattawipa Pakasri

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58S (60SiO2-36CaO-4P2O5), three-dimensionally ordered macroporous bioactive glasses (3DOM-BGs) were synthesized by the sol-gel method using dual templating methods. non-ionic surfactant Brij56 used as templates component produced mesoporous and the spherical PMMA colloidal crystals as one template component yielded either three-dimensionally ordered microporous products or shaped bioactive glass nanoparticles. The bioactive glass with aging step for 12 h at room temperature, no structure transformation occurred and the 3DOM structure was produced (Figure a) due to no shrinkage process between the aging step. After 48 h time of o 3DOM structure remained and, nanocube with ∼120 nm edge lengths and nanosphere particle with ∼50 nm was obtained (Figure c, d). PMMA packing templates have octahedral and tetrahedral holes to make 2 final shapes of 3DOM-BGs which is rounded and cubic, respectively. The ageing time change from 12h, 24h and 48h affected to the thickness of interconnecting macropores network. The wall thickness was gradually decrease after increase aging time.

Keywords: three-dimensionally ordered macroporous bioactive glasses, sol-gel method, PMMA, bioactive glass

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Authors: Jale Çatak, Bayram Yılmaz, Mustafa Ozilgen

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The second law muscle work efficiency is obtained by multiplying the metabolic and mechanical work efficiencies. Thermodynamic analyses are carried out with 19 sets of arms and legs exercise data which were obtained from the healthy young people. These data are used to simulate the changes occurring during aging. The muscle work efficiency decreases with aging as a result of the reduction of the metabolic energy generation in the mitochondria. The reduction of the mitochondrial energy efficiency makes it difficult to carry out the maintenance of the muscle tissue, which in turn causes a decline of the muscle work efficiency. When the muscle attempts to produce more work, entropy generation and exergy destruction increase. Increasing exergy destruction may be regarded as the result of the deterioration of the muscles. When the exergetic efficiency is 0.42, exergy destruction becomes 1.49 folds of the work performance. This proportionality becomes 2.50 and 5.21 folds when the exergetic efficiency decreases to 0.30 and 0.17 respectively.

Keywords: aging mitochondria, entropy generation, exergy destruction, muscle work performance, second law efficiency

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Authors: Mehdi Soltani Howyzeh, Neda Kardoni, Mani Mojadam

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To evaluate the vigor of wheat seeds and stress of premature aging effects on germination percentage, root length and shoot length of five wheat cultivars that include Vynak, Karkheh, Chamran, Star and Kavir which underwent a period of zero, two, three, four days in terms of premature aging with 41 °C temperature and 100% relative humidity. Seed germination percentage, root length and shoot length in these conditions were measured. This experiment was conducted as a factorial completely randomized design with four replications in laboratory conditions. The results showed that each of aging treatments used in this experiment can be used to detect differences in vigor of wheat varieties. Wheat cultivars illustrated significant differences in germination percentage, root length and shoot length in terms of premature aging. The wheat cultivars; Astar and Vynak had maximum germination percentage and Karkheh, respectively Kavir and Chamran had lowest percentage of seed germination. Reactions of root and shoot length of wheat cultivars was also different. The results showed that the seeds with a stronger vigor affected less in premature aging condition and the difference between the percentage of seed germination under normal conditions and stress was significant and the seeds with the weaker vigor were more sensitive to the premature aging stress and the premature aging had more severe negative impact on seed vigor.

Keywords: wheat cultivars, seed vigor, premature aging effects, germination

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Authors: Siwaporn Mahathamnuchock, Krit Phanpanya

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This survey study aims 1) to investigate the preparation of Mae Hong Son people for entering into the aging society 2) to study awareness of public health preparedness for the aging society of Mae Hong Son Province Administrative Organization. The samples used in this study were people aged 55-60 years in Mae Hong Province. Located at Khun Yuam Sub district, Khun Yuam District, Pang Ma Pha Sub district, Pang Ma Pha District, Thung Yao Sub district, Pai District, Mae ka Tuan Sub district, Sob Moei District, Mae Sariang Sub district, Mae Sariang District, Mae Tho Sub district, Mae La Noi District. And Huai Pha Sub district, Muang Mae Hong District. The data were collected from 1,088 people by Stratified sampling Method. The instrument used in this study were 36 items of questionnaire that contains three parts: 1) Sample’s general information 2) The Interview of Mae Hong Son people’s preparation before entering aging society. 3) The Interview about preparedness of health for the aging society of Mae Hong Son Province Administrative Organization. Then analyzed the data by using percentage and standard deviation. The research found that Mae Hong Son people are preparing for an aging society as followed; psychological, residence, physical health, careers and leisure time on a large scale with an average of 3.81 (SD=0.88), 3.66 (SD=0.99), 3.53(SD=1.04) and 3.51(SD=0.89), respectively. However finances and saving were prepared on moderate scale with an average of 2.84(SD=0.89) and in the awareness of public health preparedness for the aging society of Mae Hong Son Province Administrative Organization were moderate with an average of 2.99 (SD=1.07).

Keywords: aging society, preparedness, perception, Mae Hong Son province

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Authors: Linyue Jia, Wenbo Du, Zhaohui Wang, Ke Liu, Shubo Li

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Due to the great potential for weight reduction in aerospace and automotive industries, magnesium-rare earth (Mg-RE) based alloys with outstanding mechanical performance have been widely investigated for decades. However, magnesium alloys are still restricted in engineering applications because of their lower strength and ductility. Hence, there are large spaces and challenges in achieving high-performance Mg alloys. This work reports an Mg-Gd-Er-Zn-Zr alloy with ultrahigh strength and good ductility developed via hot extrusion, pre-deformation, and two-stage aging. The extruded alloy comprises fine dynamically recrystallized (DRXed) grains and coarse worked grains with a large aspect ratio. Pre-deformation has little effect on the microstructure and macro-texture and serves primarily to introduce a large number of dislocations, resulting in strain hardening and higher precipitation strengthening during subsequent aging due to more nucleation sites. As a result, the alloy exhibits a yield strength (YS) of 506 MPa, an ultimate tensile strength (UTS) of 549 MPa, and elongation (EL) of 8.2% at room temperature, showing superior strength-ductility balance than the other wrought Mg-RE alloys previously reported. The current study proposes a combination of pre-deformation and two-stage aging to further improve the mechanical properties of wrought Mg alloys for engineering applications.

Keywords: magnesium alloys, mechanical properties, microstructure, pre-deformation, two-stage aging

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Authors: Rashmi D. G., Aishwarya G., Niharika M. K.

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Purpose: Free recall tasks target cognitive and linguistic processes like episodic memory, lexical access and retrieval. Consequently, the free recall paradigm is suitable for assessing memory deterioration caused by aging; this also depends on linguistic factors, including the use of first and second languages and their relative ability. Hence, the present study aimed to determine if aging has an effect on visual and auditory recall abilities. Method: Twenty young adults (mean age: 25.4±0.99) and older adults (mean age: 63.3±3.51) participated in the study. Participants performed a free recall task under two conditions – related and unrelated and two modalities - visual and auditory where they were instructed to recall as many items as possible with no specific order and time limit. Results: Free recall performance was calculated as the mean number of correctly recalled items. Although younger participants recalled a higher number of items, the performance across conditions and modality was variable. Conclusion: In summary, the findings of the present study revealed an age-related decline in the efficiency of episodic memory, which is crucial to remember recent events.

Keywords: recall, episodic memory, aging, modality

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Authors: Yuxiao Jiang, Dong Ma, Mengyu Zhan, Yingxia Yun

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China now is entering the phase of old aging and the aging speed is on acceleration. The proportion of the aged citizens in the urban areas is getting larger. Traveling on foot is one of the main travel methods for the old, but the bad walking environment and unsystematic pedestrian system cause inconvenience to the old who travel on foot. The paper analyzes the behavioral characteristics and the spatial preferences of the elderly group as well as the new traffic demands of them, finding out that some problems exist in the current pedestrian system. Thus, the paper proposes strategies in the areas of planning and design, and engineering technology so as to promote the traffic environment and perfect the pedestrian system for the old people.

Keywords: old aging, pedestrian system, perfection strategies, travel characteristics, future demand

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Authors: S. Mahovic Poljacek, T. Tomasegovic, T. Cigula, D. Donevski, R. Szentgyörgyvölgyi, S. Jakovljevic

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In this paper, a degradation of the photopolymeric material (PhPM), used as printing plate in the flexography reproduction technique, caused by accelerated aging has been observed. Since the basis process for production of printing plates from the PhPM is a radical cross-linking process caused by exposing to UV wavelengths, the assumption was that improper storage or irregular handling of the PhPM plate can change the surface and structure characteristics of the plates. Results have shown that the aging process causes degradation in the structure and changes in the surface of the PhPM printing plate.

Keywords: aging process, artificial treatment, flexography, photopolymeric material (PhPM)

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Authors: Songul Kurucay, Mustafa Acarer, Harun Sepet

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Static strain aging occurs when metallic materials are subjected to deformation and then heat treated at low temperatures such as 150-200oC. Static strain aging occurs in BCC metals and results and increasing in yield and tensile strength and decreasing ductility due to carbon and/or nitrogen atoms locking dislocations. The locked dislocations increase yield and tensile strength. In this study, static strain aging behaviors of ferritic and austenitic stainless steel were investigated. Ferritic stainless steel was prestained at %5, %10 and %15 and then aged at 150oC and 200oC for 30 minutes. Austenitic stainless steel was also prestained at %20 and %30 and then heat treated at 200, 400 and 600oC for 30 minutes. After the heat treatment, the tensile test was performed to determine the effect of prestain and heat treatment on the steels. Hardness measurements and detailed microstructure characterization were also done. While AISI 430 ferritic stainless steel sample which was prestained at 15% and aged at 200oC, showed the highest increasing in the yield strength, AISI 304 austenitic stainless steel which was prestained at 30% and aged at 600oC, has the highest yield strength. Microstructure photographs also support the mechanical test results.

Keywords: austenitic stainless steel, ferritic stainless steel, static strain aging, tensile strength

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Authors: Jifeng Zhang , Yongpeng Lei

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Continuous carbon fiber reinforced polyamide 6 (CF/PA6) composites are potential for application in the automotive industry due to their high specific strength and stiffness. However, PA6 resin is sensitive to the moisture in the hydrothermal environment and CF/PA6 composites might undergo several physical and chemical changes, such as plasticization, swelling, and hydrolysis, which induces a reduction of mechanical properties. So far, little research has been reported on the assessment of the effects of hydrothermal aging on the mechanical properties of continuous CF/PA6 composite. This study deals with the effects of hydrothermal aging on moisture absorption and mechanical properties of polyamide 6 (PA6) and polyamide 6 reinforced with continuous carbon fibers composites (CF/PA6) by immersion in distilled water at 30 ℃, 50 ℃, 70 ℃, and 90 ℃. Degradation of mechanical performance has been monitored, depending on the water absorption content and the aging temperature. The experimental results reveal that under the same aging condition, the PA6 resin absorbs more water than the CF/PA6 composite, while the water diffusion coefficient of CF/PA6 composite is higher than that of PA6 resin because of interfacial diffusion channel. In mechanical properties degradation process, an exponential reduction in tensile strength and elastic modulus are observed in PA6 resin as aging temperature and water absorption content increases. The degradation trend of flexural properties of CF/PA6 is the same as that of tensile properties of PA6 resin. Moreover, the water content plays a decisive role in mechanical degradation compared with aging temperature. In contrast, hydrothermal environment has mild effect on the tensile properties of CF/PA6 composites. The elongation at breakage of PA6 resin and CF/PA6 reaches the highest value when their water content reaches 6% and 4%, respectively. Dynamic mechanical analysis (DMA) and scanning electron microscope (SEM) were also used to explain the mechanism of mechanical properties alteration. After exposed to the hydrothermal environment, the Tg (glass transition temperature) of samples decreases dramatically with water content increase. This reduction can be ascribed to the plasticization effect of water. For the unaged specimens, the fibers surface is coated with resin and the main fracture mode is fiber breakage, indicating that a good adhesion between fiber and matrix. However, with absorbed water content increasing, the fracture mode transforms to fiber pullout. Finally, based on Arrhenius methodology, a predictive model with relate to the temperature and water content has been presented to estimate the retention of mechanical properties for PA6 and CF/PA6.

Keywords: continuous carbon fiber reinforced polyamide 6 composite, hydrothermal aging, Arrhenius methodology, interface

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Authors: Burak Bal, Demircan Canadinc

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Dynamic strain aging (DSA), resulting from the reorientation of C-Mn clusters in the core of dislocations, can provide a strain hardening mechanism. In addition, in Hadfield steel, negative strain rate sensitivity is observed due to the DSA. In our study, we incorporated dynamic strain aging onto crystal plasticity computations to predict the local instabilities and corresponding negative strain rate sensitivity. Specifically, the material response of Hadfield steel was obtained from monotonic and strain-rate jump experiments under tensile loading. The strain rate range was adjusted from 10⁻⁴ to 10⁻¹s ⁻¹. The crystal plasticity modeling of the material response was carried out based on Voce-type hardening law and corresponding Voce hardening parameters were determined. The solute pinning effect of carbon atom was incorporated to crystal plasticity simulations at microscale level by computing the shear stress contribution imposed on an arrested dislocation by carbon atom. After crystal plasticity simulations with modifying hardening rule, which takes into account the contribution of DSA, it was seen that the model successfully predicts both the role of DSA and corresponding strain rate sensitivity.

Keywords: crystal plasticity, dynamic strain aging, Hadfield steel, negative strain rate sensitivity

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Authors: Juyon Lee, Myoungjin Park, Jonghoon Kim, Jaekook Ha, Chanhee Lee

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We demonstrated a new positive aging methods of QLEDs devices that can apply in large size inkjet printing display. Conventional positive aging method using photo-curable resin remains unclear mechanism of the phenomenon and also there are many limitations to apply large size panels in commercial process. Through the photo acid generator (PAG) in ETL Ink, we achieved 90% of the efficiency of the conventional method and up to 1000h life time stability (T80). This techniques could be applied to next generation of QLEDs panels and also can prove the working mechanism of positive aging in QLED related to modification of ZnMgO NPs.

Keywords: quantum dots, QLED, printing, positive aging, ZnMgO NPs

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Authors: HoYoung Son, DongHoon Shin, WooYoung Jung

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This study presented the seismic fragility framework of concrete weir structure subjected to strong seismic ground motions and in particular, concrete aging condition of the weir structure was taken into account in this study. In order to understand the influence of concrete aging on the weir structure, by using probabilistic risk assessment, the analytical seismic fragility of the weir structure was derived for pre- and post-deterioration of concrete. The performance of concrete weir structure after five years was assumed for the concrete aging or deterioration, and according to after five years’ condition, the elastic modulus was simply reduced about one–tenth compared with initial condition of weir structures. A 2D nonlinear finite element analysis was performed considering the deterioration of concrete in weir structures using ABAQUS platform, a commercial structural analysis program. Simplified concrete degradation was resulted in the increase of almost 45% of the probability of failure at Limit State 3, in comparison to initial construction stage, by analyzing the seismic fragility.

Keywords: weir, FEM, concrete, fragility, aging

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Authors: M. Dezyani, R. Ezzati belvirdi, M. Shakerian, H. Mirzaei

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The effect of Microfiltration (MF) on proteolysis, hardness, and flavor of Feta cheese during 6 mo of aging was determined. Raw skim milk was microfiltered two-fold in two cheese making trials. In trial 1, four vats of cheese were made in 1 d using unconcentrated milk (1X), 1.26X, 1.51X, and 1.82X Concentration Factors (CF). Casein-(CN)-to-fat ratio was constant among treatments. Proteolysis during cheese aging decreased with increasing CF due to either limitation of substrate availability for chymosin due to low moisture in the nonfat substance (MNFS), inhibition of chymosin activity by high molecular weight milk serum proteins, such as α2-macroglobulin, retained in the cheese or low residual chymosin in the cheese. Hardness of fresh cheese increased, and cheese flavor intensity decreased with increasing CF. In trial 2, the 1X and 1.8X CF were compared directly. Changes made in the cheese making procedure for the 1.8X CF (more chymosin and less cooking) increased the MNFS and made proteolysis during aging more comparable for the 1X and 1.8X cheeses. The significant difference in cheese hardness due to CF in trial 1 was eliminated in trial 2. In a triangle test, panelists could not differentiate between the 1X and 1.8X cheeses. Therefore, increasing chymosin and making the composition of the two cheeses more similar allowed production of aged Fetta cheese from milk concentrated up to 1.8X by MF that was not perceived as different from aged feta cheese produced without MF.

Keywords: feta cheese, microfiltration, concentration factor, proteolysis

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Authors: S. H. Bae, D. W. Cho, W. B. Jeong, J. R. Cho

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Fatigue fracture of an aluminum welded structure is a phenomenon frequently occurring from pores in a weld. In order to grasp the state of the welded structure in operation in real time, the acceleration signal of the structure is measured. At this time, the vibration characteristic of the signal according to the fatigue load is an important parameter of the state diagnosis. This paper was an experimental study on the variation of vibration characteristics of welded beams with vibration aging (especially bending vibration). First simple beams were produced according to welding conditions. Each beam was vibrated and measured beam's PSD (power spectral density) according to the degree of aging. Also, modal testing was conducted to compare the transfer functions of welded beams. Testing result shows that the natural frequencies of the beam changed with the vibration aging due to the change of stiffness in welding part and its stiffness was estimated by the finite element method.

Keywords: modal testing, natural frequency, vibration aging, welded structure

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Authors: Sakkaphat T. Ngamake, Arunya Tuicomepee, Panrapee Suttiwan, Rewadee Watakakosol, Sompoch Iamsupasit

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Generally, 'positive' emotion regulation strategies such as cognitive reappraisal have linked to desirable outcomes while 'negative' strategies such as behavioral suppression have linked to undesirable outcomes. These trends have been found in both the elderly and professional practitioners. Hence, this study sought to investigate these trends further by examining the relationship between two dominant emotion regulation strategies in the literature (i.e., cognitive reappraisal and behavioral suppression) and well-being outcomes among the elderly (i.e., successful aging) and their caregivers (i.e., satisfaction with life), using the actor-partner interdependence model. A total of 150 elderly-caregiver dyads participated in the study. The elderly responded to two measures assessing the two emotion regulation strategies and successful aging while their caregivers responded to the same emotion regulation measure and a measure of satisfaction with life. Two criterion variables (i.e., successful aging and satisfaction with life) were specified as latent variables whereas four predictors (i.e., two strategies for the elderly and two strategies for their caregivers) were specified as observed variables in the model. Results have shown that, for the actor effect, the cognitive reappraisal strategy yielded positive relationships with the well-being outcomes for both the elderly and their caregivers. For the partner effect, a positive relationship between caregivers’ cognitive reappraisal strategy and the elderly’s successful aging was observed. The behavioral suppression strategy has not related to any well-being outcomes, within and across individual agents. This study has contributed to the literature by empirically showing that the mental activity of the elderly’s immediate environment such as their family members or close friends could affect their quality of life.

Keywords: emotion regulation, caregiver, older adult, well-being

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Authors: Ricardo Mendoza, Jason Briceño, Juan F. Santa, Gabriel Peluffo, Mauricio Márquez, Beatriz Cardozo, Carlos Gutiérrez

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Coir natural fiber reinforced polyester composites were exposed to an accelerated environment aging in order to study the influence on the mechanical properties. Coir fibers were obtained in local plantations of the Caribbean coast of Colombia. A physical and mechanical characterization was necessary to found the best behavior between three types of coconut. Composites were fabricated by hand lay-up technique and samples were cut by water jet technique. An accelerated aging test simulates environmental climate conditions in a hygrothermal and ultraviolet chamber. Samples were exposed to the UV/moisture rich environment for 500 and 1000 hours. The tests were performed in accordance with ASTM G154. An additional water absorption test was carried out by immersing specimens in a water bath. Mechanical behaviors of the composites were tested by tensile, flexural and impact test according to ASTM standards, after aging and compared with unaged composite specimens. It was found that accelerated environment aging affects mechanical properties in comparison with unaged ones. Tensile and flexural strength were lower after aging, meantime elongation at break and flexural deflection increased. Impact strength was found that reduced after aging. Other result revealed that the percentage of moisture uptake increased with aging. This results showed that composite materials reinforced with natural fibers required an improvement adding a protective barrier to reduce water absorption and increase UV resistance.

Keywords: coir fiber, polyester composites, environmental aging, mechanical properties

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Authors: Xuemei Yang, Xin Sun, Cheng Fu, Qiong Lan, Chao Han

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Residual stresses, which can be produced during the manufacturing process of plastic bonded explosive (PBX), play an important role in weapon system security and reliability. Residual stresses can and do change in service. This paper mainly studies the influence of vibratory stress relief (VSR) and thermal aging on residual stress of explosives. Firstly, the residual stress relaxation of PBX via different physical condition of VSR, such as vibration time, amplitude and dynamic strain, were studied by drill-hole technique. The result indicated that the vibratory amplitude, time and dynamic strain had a significant influence on the residual stress relief of PBX. The rate of residual stress relief of PBX increases first and then decreases with the increase of dynamic strain, amplitude and time, because the activation energy is too small to make the PBX yield plastic deformation at first. Then the dynamic strain, time and amplitude exceed a certain threshold, the residual stress changes show the same rule and decrease sharply, this sharply drop of residual stress relief rate may have been caused by over vibration. Meanwhile, the comparison between VSR and thermal aging was also studied. The conclusion is that the reduction ratio of residual stress after VSR process with applicable vibratory parameters could be equivalent to 73% of thermal aging with 7 days. In addition, the density attenuation rate, mechanical property, and dimensional stability with 3 months after VSR process was almost the same compared with thermal aging. However, compared with traditional thermal aging, VSR only takes a very short time, which greatly improves the efficiency of aging treatment for explosive materials. Therefore, the VSR could be a potential alternative technique in the industry of residual stress relaxation of PBX explosives.

Keywords: explosives, residual stresses, thermal aging, vibratory stress relief, VSR

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Authors: Nasir A. Al-Geelani, Zulkurnain Abdul-Malek, M. Afendi M. Piah

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This research paper investigation is carried out in the laboratory on single units of transmission line glass insulator characterized by different thermal images, which aimed to find out the age of the insulators. The tests were carried out on virgin and aged insulators using the thermography scan. Various samples having different periods of aging 20, 15, and 5 years from a 132 kV transmission line which have exhibited a different degree of corrosion. The second group of insulator samples was relatively mild aged insulators, while the third group was lightly aged; finally, the fourth group was the brand new insulators. The results revealed a strong correlation between the aging and the thermal images captured by the infrared camera. This technique can be used to monitor the aging of high voltage insulators as a precaution to avoid disaster.

Keywords: glass insulator, infrared camera, corona diacharge, transmission lines, thermograpy, surface discharge

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Authors: Zoe Yang, Dena Shenk

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The goal of this research was to highlight stories from voices that are typically disregarded. Five older Asian Americans, who immigrated from Cambodia, Taiwan, and China, were interviewed in person, over Zoom, or through a phone call. Subjects were asked about their opinions towards aging and housing choices. Various Asian American stories reveal factors that contribute to the acceptance or rejection of aging. Through these interviews and research on cultural differences towards aging, findings indicate that personality, age, background, and health status affect one's relationship with housing choices and filial piety.

Keywords: assisted living, filial piety, housing choices, independent living

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Authors: Wan-I Chen, Tsung-I Pai

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Future the society aging of population will create the social problem has not had the good mechanism solution in the Asian country, especially in Taiwan. In the future ten year the people in Taiwan must facing the condition which is localization aging social problem. In this situation, how to use the spatial in eco way to development space use to solve the old age spatial demand is the way which might develop in the future Taiwan society. Over the next 10 years, taking care of the aging people will become part of the social problem of aging phenomenon. The research concentrate in the feasibility of spatial substitution, secondary use of spatial might solve out of spatial problem for aging people. In order to prove the space usable, the research required to review the project with the support system and infill system for space experiment, by using network grid way. That defined community level of space elements location relationship, make new definitions of space and return to cooperation. Research to innovation in the the appraisal space causes the possibility, by spatial replacement way solution on spatial insufficient suitable condition. To evaluation community spatial by using the support system and infill system in order to see possibilities of use in replacement inner space and modular architecture into housing. The study is discovering the solution on the Eco way to develop space use to figure out the old age spatial demand.

Keywords: sustainable use, space conversion, integration, replacement


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Authors: M. M. Morgham, A. A. Hameda, N. A. Zriba, H. A. Jawan

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This paper aims to study the effect of cold work condition on the microstructure of Cu-1.5wt%Ti, and Cu-3.5wt%Ti and hence mechanical properties. The samples under investigation were machined and solution heat treated. X-ray diffraction technique is used to identify the different phases present after cold deformation by compression and also different heat treatment and also measuring the relative quantities of phases present. Metallographic examination is used to study the microstructure of the samples. The hardness measurements were used to indicate the change in mechanical properties. The results are compared with the mechanical properties obtained by previous workers. Experiments on cold compression followed by aging of Cu-Ti alloys have indicated that the most effective hardening of the material results from continuous precipitation of very fine particles within the matrix. These particles were reported to be β`-type, Cu4Ti phase. The β`-β transformation and particles coarsening within the matrix as well as a long grain boundaries were responsible for the averaging of Cu-1.5wt%Ti and Cu-3.5wt%Ti alloys. It is well know that plate like particles are β – type, Cu3Ti phase. Discontinuous precipitation was found to start at the grain boundaries and expand into grain interior. At the higher aging temperature a classic widmanstätten morphology forms giving rise to a coarse microstructure comprised of α and the equilibrium phase β. Those results were confirmed by X-ray analysis, which found that a few percent of Cu3Ti, β precipitates are formed during aging at high temperature for long time for both Cu- Ti alloys (i.e. Cu-1.5wt%Ti and Cu-3.5wt%Ti).

Keywords: metallographic, hardness, precipitation, aging

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Authors: M. Shadmand

Abstract:

The curing process of insulation system for electrical machines plays a determinative role for its durability and reliability. Polar structure of insulating resin molecules and used filler of insulation system can be taken as an occasion to leverage it to enhance overall characteristics of insulation system, mechanically and electrically. The curing process regime for insulating system plays an important role for its mechanical and electrical characteristics by arranging the polymerization of chain structure for resin. In this research, the effect of electrical field application on in-curing insulating system for Global Vacuum Pressurized Impregnation (GVPI) system for traction motor was considered by performing the dissipation factor, polarization and de-polarization current (PDC) and voltage endurance (aging) measurements on sample test objects. Outcome results depicted obvious improvement in mechanical strength of the insulation system as well as higher electrical characteristics with routing and long-time (aging) electrical tests. Coming together, polarization of insulation system during curing process would enhance the machine life time. 

Keywords: insulation system, GVPI, PDC, aging

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Authors: Faizan Asghar, Mohammad Jamal Khattak

Abstract:

Aging, in general, refers to changes in rheological characteristics of asphalt mixture due to changes in chemical composition over the course of construction and service life of the pavement. The main goal of this study was to investigate the impact of oxidation on fatigue characteristics of a novel HMA composite fabricated with a combination of crumb rubber (CRM) and polyvinyl alcohol (PVA) fiber subject to aging of 7 and 14 days. A flexural beam fatigue test was performed to evaluate several characteristics of control, CRM modified, PVA reinforced, and novel rubber-fiber HMA composite. Experimental results revealed that aging had a significant impact on the fatigue performance of novel HMA composite. It was found that a suitable proportion of CRM and PVA radically affected the performance of novel rubber-fiber HMA in resistance to fracture and fatigue cracking when subjected to long-term aging. The developed novel HMA composite containing 2% CRM and 0.2% PVA presented around 29 times higher resistance to fatigue cracking for a period of 7 days of aging. To develop a cumulative plastic deformation level of 250 micros, such a mixture required over 50 times higher cycles than control HMA. Moreover, the crack propagation rate was reduced by over 90%, with over 12 times higher energy required to propagate a unit crack length in such a mixture compared to conventional HMA. Further, digital imaging correlation analyses revealed a more twisted and convoluted fracture path and higher strain distribution in rubber-fiber HMA composite. The fatigue performance after long-term aging of such novel HMA composite explicitly validates the ability to withstand load repetition that could lead to an extension in the service life of pavement infrastructure and reduce taxpayers’ dollars spent.

Keywords: crumb rubber, PVA fibers, dry process, aging, performance testing, fatigue life

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Authors: Ellie Fini, Mahour Parast, Daniel Oldham, Shahrzad Hosseinnezhad

Abstract:

This paper investigates the relationship between molecular species of four different bio-based adhesives (made from Swine Manure, Miscanthus Pellet, Corn Stover, and Wood Pellet) and their rheological behavior before and after they undergo extensive oxidative aging. To study the effect of oxidative aging on the chemical structure of bio-adhesives, Infrared Attenuated Total Reflectance Spectroscopy (Fourier transform infrared) was utilised. In addition, a Drop Shape Analyser, Rotational Viscometer, and Dynamic Shear Rheometer were used to evaluate the surface properties and rheological behaviour of each bio-adhesive. Overall, bio-adhesives were found to be significantly different in terms of their ageing characteristics. Accordingly, their surface and rheological properties were found to be ranked differently before and after ageing. The results showed that the bio-adhesive from swine manure is less susceptible to aging compared to plant-based bio-oils. This can be further attributed to the chemical structure and the high lipid contents of the bio-adhesive from swine manure, making it less affected by oxidative ageing.

Keywords: bio-adhesive, rheology, bio-mass, material genome

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Authors: Chia-Jung Li, Kuan-Hao Tsui

Abstract:

As women age, the quality of their oocytes deteriorates irreversibly, leading to reduced fertility. To better understand the role of Ferroptosis-related genes in ovarian aging, we employed a multi-omics analysis approach, including spatial transcriptomics, single-cell RNA sequencing, human ovarian pathology, and clinical biopsies. Our study identified excess lipid peroxide accumulation in aging germ cells, metal ion accumulation via oxidative reduction, and the interaction between ferroptosis and cellular energy metabolism. We used multi-histological prediction of ferroptosis key genes to evaluate 75 patients with ovarian aging insufficiency and then analyzed changes in hub genes after supplementing with DHEA, Ubiquinol CoQ10, and Cleo-20 T3 for two months. Our results demonstrated a significant increase in TFRC, GPX4, NCOA4, and SLC3A2, which were consistent with our multi-component prediction. We theorized that these supplements increase the mitochondrial tricarboxylic acid cycle (TCA) or electron transport chain (ETC), thereby increasing antioxidant enzyme GPX4 levels and reducing lipid peroxide accumulation and ferroptosis. Overall, our findings suggest that supplementation intervention significantly improves IVF outcomes in senescent cells by enhancing metal ion and energy metabolism and enhancing oocyte quality in aging women.

Keywords: multi-omics, nutrients, ferroptosis, ovarian aging

Procedia PDF Downloads 53