This research considered the effect of non-natural aging on the microstructural characteristics and mechanical properties of as-cast aluminum 6063 alloys. The samples were developed through a sand casting process and ...This research considered the effect of non-natural aging on the microstructural characteristics and mechanical properties of as-cast aluminum 6063 alloys. The samples were developed through a sand casting process and machined into tensile and impact test samples before carrying out solution heat treatment at 550?C (0.83 T<sub>m</sub>) on two parts of the samples while retaining one part as the control. The two parts were further divided into sets denoted A and B and were aged at 180?C (0.27 T<sub>m</sub>) and 160?C (0.24 T<sub>m</sub>), respectively, for 12 hours. The results showed that sample A has the optimal yield strength and ultimate tensile strength of 192 and 206 MPa, respectively. Likewise, the sample gave the highest impact strength value of about 9.63 J/mm<sup>2</sup>. The observed results were supported by the optical micrograph, which revealed that the sample has evenly dispersed precipitates in its microstructure. This is deemed responsible for the observed increase in strength of the sample.展开更多
The Irvingia gabonensis kernels, which have been extensively studied for their numerous virtues, including the ability to act against the accumulation of fats in the body[1], contain an oil. The aging of this oil unde...The Irvingia gabonensis kernels, which have been extensively studied for their numerous virtues, including the ability to act against the accumulation of fats in the body[1], contain an oil. The aging of this oil under two different conditions of conservation was the subject of our work. One of the results was an increase in the content of long-chain carbonaceous fatty acids during aging for 11 months of storage at low temperature (6℃) and at 30℃. This behavior does not find a concordant explanation by the comparative analysis of the chemical indices. Hence, there is the need to use the Medium Infra-Red spectroscopy (MIR) which allowed to clarify the information of the saponification index, to justify the weakness of the formation of peroxides in the case of the conservation at 30℃ and to confirm the information given by the peroxide index. It also allowed to understand the formation of the long carbon chains by the “cis-trans” isomerization and the homolytic cuts which intervene within the matrix of the fat by the analysis of the number of -CH<sub>2</sub> and -CH<sub>3</sub> groups in the two conditions of conservation. This study reveals that the rapid solidification of Irvingia gabonensis oil at room temperature[2] is an advantage for its preservation at room temperature but a great weakness when the fat is stored at low temperature.展开更多
Asphalt binder is inevitably aged by ultraviolet(UV)light during its service period.UV ageing can significantly decrease the technical properties of asphalt binder.The sensitivity of asphalt to UV ageing and thermal-o...Asphalt binder is inevitably aged by ultraviolet(UV)light during its service period.UV ageing can significantly decrease the technical properties of asphalt binder.The sensitivity of asphalt to UV ageing and thermal-oxidative ageing differs,such that the UV ageing performance cannot be determined based on the thermal-oxidative ageing performance.Previous researches mainly focused on the chemical composite and technical performance changes of asphalt binder during UV ageing,and the UV light parameters effect on the ageing rate of asphalt binder.However,the theory for characterizing and explaining the development of UV ageing depth does not get too much attentions,and the UV ageing mechanism of asphalt binder is not very clear.Therefore,it cannot guide to develop or select the good methods or anti-UV ageing additives for asphalt binders.This paper focuses on the latest researches of the mechanisms and anti-ageing methods of asphalt binders.With the increase of UV ageing time,the UV ageing of asphalt binder develops gradually from the surface to inner part.There are various methods,such as low-penetration grade asphalt,less air void ratio,UV stabilizers and UV light absorbers,that can improve the UV ageing resistance of asphalt binders.A new theory of sensitive wavelengths of asphalt UV ageing is proposed,which can enrich the basic theory of asphalt UV ageing.Depending on this theory,different wavelengths of UV light have different ageing effects on asphalt binder.The composite anti-UV ageing additives with barrier and specific absorption effects on UV light is proposed,and may have better improvement effect on the anti-UV ageing performance of asphalt binder.展开更多
The effects of stress,ageing time and ageing temperature on creep behavior of poly(methyl methacrylate) were studied.After annealing above its glass transition temperature for a period of time to eliminate the stress ...The effects of stress,ageing time and ageing temperature on creep behavior of poly(methyl methacrylate) were studied.After annealing above its glass transition temperature for a period of time to eliminate the stress and thermal history,the specimens were quenched and aged at various ageing temperatures for different ageing time,and then the short-term creep tests under different stress levels were carried out at room temperature.The creep strains were modeled by means of time-ageing time equivalence and time-stress equivalence,and the master creep curves were constructed via ageing time shift factors and stress shift factors.The results indicate that the creep rate increases with stress,while decreases with ageing time,and the ageing temperature history obviously affects the creep rate.For linear viscoelastic material,the ageing shift rate is independent on imposed stress,while for nonlinear viscoelastic material,the ageing shift rate decreases with increasing stress.The unified master creep curve up to 540 d at reference state was constructed by shifting the creep curves horizontally along the logarithmic time axis to overlap each other.It is demonstrated that the time-stress equivalence,united with the time-ageing time equivalence,provides an effective accelerated characterization technique in the laboratory to evaluate the long-term creep behavior of physical ageing polymers.展开更多
Increased life expectancy has led to policy interest in adding quality to years of life and in related concepts such as attitudes to ageing. Improving attitudes to ageing is regarded as one means of improving the part...Increased life expectancy has led to policy interest in adding quality to years of life and in related concepts such as attitudes to ageing. Improving attitudes to ageing is regarded as one means of improving the participation and contribution of older people within society. In considering age- related attitudes in the dynamic nature of social identity, age is not just one social category that may or may not constitute a part of one’s identity. Other identities such as gender may be more salient in attitudes to ageing. The purpose of this study was to explore Norwegian gender differences in attitudes to ageing among 282 females and 200 males living in the community. Attitudes to ageing were measured using the Attitudes to Ageing Questionnaire (AAQ;Laidlaw, Power, Schmidt, & the WHOQOL-OLD Group, 2007). Both genders in this study had positive attitudes toward their ageing, in spite of acknowledging loss with problems of exclusion, making friends and talking about difficult feelings. Compared to men, women perceived ageing as a time of greater loss, however, they felt more strongly that ageing brought wisdom and that their life had made a difference. On the other hand, men felt more strongly that physical problems did not hold them back from doing what they wanted to do and believed more strongly that they passed on their experiences to others. Both genders felt that their identity was not defined by age, they didn’t feel old, aging was a privilege, and appraised the importance of exercising. Attitudes to ageing are becoming increasingly important in ageing societies. Such positive attitudes should be regarded with importance to health professionals, leaders and policy makers in planning interventions to buffer the detrimental aspects of ageing.展开更多
The kinetics of the thermal decomposition for a naturally ageing ammonium perchlorate(AP) and hydroxyl-terminated-polybutadiene(HTPB) base bleed composite propellant were investigated using a differential scanning cal...The kinetics of the thermal decomposition for a naturally ageing ammonium perchlorate(AP) and hydroxyl-terminated-polybutadiene(HTPB) base bleed composite propellant were investigated using a differential scanning calorimetry(DSC). The naturally ageing AP/HTPB base bleed propellant samples have been stored in a sealed plastic bag at room temperature(5-25 ℃) for more than 20 years. The experimental DSC results were obtained by placing samples(each about 1.5 mg) in a sealed pan under non-isothermal condition under different heating rates, 5.0, 10.0, 15.0, 20.0 and 30.0 ℃·min^(-1). The activation energy and pre-exponential factor were estimated based on the relationship between the exothermic peak temperature and the heating rate by Ozawa and Kissinger methods, respectively. The decomposition kinetic parameters is lower the values under laboratorial aging condition.展开更多
Experimental results of the investigation on the hardness of two Al-Zn-Mg alloys [Al-10.0 Zn- 4.0 Mg and Al-8.5 Zn-3.0 Mg (wt pct)] aged in the temperature range 60-310℃ for different intervals of time from 1/4 h to ...Experimental results of the investigation on the hardness of two Al-Zn-Mg alloys [Al-10.0 Zn- 4.0 Mg and Al-8.5 Zn-3.0 Mg (wt pct)] aged in the temperature range 60-310℃ for different intervals of time from 1/4 h to 168 h are presented. Both the alloys were found to show identical behaviour of hardness with ageing time. Alloy with higher Zn and Mg content had higher hardness than the alloy with lower solute content. There were three ranges of temperature in which different types of precipitates formed and affected the hardness. Some of the grain boundaries were found to migrate and precipitate free zone has been observed.展开更多
Ageing is one of the greatest risk factors for neurodegenerative diseases.How the complex biological changes in ageing increase the brain’s susceptibility to neurodegeneration remains incompletely understood.Research...Ageing is one of the greatest risk factors for neurodegenerative diseases.How the complex biological changes in ageing increase the brain’s susceptibility to neurodegeneration remains incompletely understood.Research into neurodegenerative disorders has shifted from a neuron-centric approach,to the contributing roles of age-related neurovascular and glial cell dysfunction.展开更多
The fatigue properties of asphalts were investigated after various laboratory simulation ageing tests and outdoor natural exposure ultraviolet radiation ageing,by dynamic shear rheometer(DSR) time sweep fatigue test i...The fatigue properties of asphalts were investigated after various laboratory simulation ageing tests and outdoor natural exposure ultraviolet radiation ageing,by dynamic shear rheometer(DSR) time sweep fatigue test in constant strain model and a new type of specimen which was introduced to avoid the problem of adhesion failure between rotor and asphalt binder.The results show that outdoor natural exposure ageing(NEA) causes the decrease of retained fatigue life distinctly,and photodegradation caused by outdoor NEA of 1 250 μm thin films asphalt for three months,is found to be severer than pressure ageing vessel(PAV) with respects to retained fatigue life.The effect of photodegradation increases as the time of outdoor NEA increases.DSR time sweep fatigue test in constant strain indicates that the aged styrene-butadiene-styrene(SBS) modified asphalt still displays better fatigue properties than the corresponding base asphalt after ageing.展开更多
North East Asian countries are facing to rapid increase in aged population ratio.The most recent values of aged population ratios are 19.5%,8.7%,and 6.9%,for Japan,Korea and China,respectively.One of the welfare servi...North East Asian countries are facing to rapid increase in aged population ratio.The most recent values of aged population ratios are 19.5%,8.7%,and 6.9%,for Japan,Korea and China,respectively.One of the welfare services in the aged society is provision of assistive products.Electronic control systems are commonly adopted in modern assistive products and sensors are indispensable for control units.Alarm systems,such as fire alarm,smoke detectors,and gas leak detectors,have been regarded as indispensable to safety of elderly persons and persons with disability.Main application of chemical sensors in home care of elderly persons is in the field of personal care and personal medical treatment.Products for personal medical treatment include that for medical treatment in home care and that to keep elderly persons healthy.Large market is expected in the latter one.展开更多
The ageing behavior of the mechanically alloyed Cu-15Ni-8Sn alloy has been studied. Compared with the alloys prepared by casting and rapid solidification, the modulation structure developed during ageing process of th...The ageing behavior of the mechanically alloyed Cu-15Ni-8Sn alloy has been studied. Compared with the alloys prepared by casting and rapid solidification, the modulation structure developed during ageing process of those prepared by mechanical alloying is finer and much more uniform, which leads to a higher peak hardness. However, their spinodal decomposition temperature are almost the same. Cold deformation prior to ageing not only accelerates the ageing process but also increases the peak hardness of the alloy.展开更多
The study aimed to investigate and compare the contents of carboxymethyllysine(CML)in two kinds of broilers during postmortem ageing and storage.The contents of CML in raw and boiled(100℃,30 min)broiler briskets and ...The study aimed to investigate and compare the contents of carboxymethyllysine(CML)in two kinds of broilers during postmortem ageing and storage.The contents of CML in raw and boiled(100℃,30 min)broiler briskets and legs which were from white feather broilers(n=8)and yellow feather broilers(n=8)with ageing and storage at 4℃for 0-168 h were determined.Postmortem ageing and storage had a significant(P<0.05)effect on the color and A;in both boiled broilers meat.In addition,with the ageing and storage time increasing,CML content in raw white feather broiler brisket meat had no significant(P>0.05)change,while that in boiled brisket meat significantly(P<0.05)increased during 0-6 h,then decreased during 6-24 h,finally increased again.CML content in leg meat increased significantly(P<0.05)with the ageing and storage time prolonging.But postmortem ageing and storage had no significant(P>0.05)effect on the CML contents in raw/boiled yellow feather broilers.Meanwhile,CML contents in white feather broilers were much higher than that in yellow feather broilers.Thus,white feather broilers can be selected as the research object to study the mechanism of ageing and storage on CML content in the postmortem broiler in the future.展开更多
The paper provides a general overview of chemical processes leading to the degradation of oil-paper insulation in oil-immersed electrical current transformers. Previous knowledge available in literature is complemente...The paper provides a general overview of chemical processes leading to the degradation of oil-paper insulation in oil-immersed electrical current transformers. Previous knowledge available in literature is complemented by new results placing a specific emphasis on the physicochemical factors which affect the copper release in the insulation oil and the oil oxidation kinetics. It is demonstrated that various ageing processes interact with each other, with one or another process dominating under specific conditions. Comprehensive but disjoint studies focusing on separate sub-processes may produce rather misleading results, and occasionally, lie behind rather irrelevant quality demands imposed on the insulating liquids.展开更多
Spherulitic morphology of pure poly lactic acid (PLLA) PLLA have investigated after thermal annealing. The morphology of spherulite of pure poly lactic acid (PLLA) PLLA have investigated after thermal annealing. The e...Spherulitic morphology of pure poly lactic acid (PLLA) PLLA have investigated after thermal annealing. The morphology of spherulite of pure poly lactic acid (PLLA) PLLA have investigated after thermal annealing. The effect of both annealing temperature and crystallization temperature on the formation of cracks was described by polarized optical microscope (POM). Non banded spherulite (fibrils) with cracks was detected in PLLA film after annealing at 160°C (180 min.) and isothermal crystallization temperatures at 140°C and 150°C. With increasing temperature after annealing treatment the size of spherulite is increased and more cracks are formed. The maximum growth rate of spherulites was found at 130°C. The physical ageing was carried out by annealing the PLLA sample at room temperature for several annealing time (ta) from 0 h to 720 h. The enthalpy relaxation has been studied by differential scanning calorimetry (DSC) through analysis of the endothermic peak of glass transition temperature, which increased and shifted towards higher temperature as the annealing time increased.展开更多
Poor adventitious root formation is a major obstacle in micropropagation and in conventional propagation. The effects of LaCl3 on root growth and deferring the root ageing of peach plantlet in vitro were investigated....Poor adventitious root formation is a major obstacle in micropropagation and in conventional propagation. The effects of LaCl3 on root growth and deferring the root ageing of peach plantlet in vitro were investigated. The results show that the optimum concentration of LaCl3 （2.5 μmol·L -1） in the rooted medium can significantly increase the rooting rate, the root length and the fresh weight, promote the activities of superoxide dismutase （SOD）; catalase （CAT） and peroxidase （POD） and decrease the production rate of O2 ·-, the malondialdehyde （MDA） contents and the plasma membrane permeability. There are important theory meaning and practical value in applying LaCl3 in the rooting medium to raise the rate of rooting and transplant for stone fruit tree.展开更多
This paper estimates the population to be influenced by China's policy of postponed retirement age and provides design strategies and suggestions in the workplace for the ageing workforce from the perspective of i...This paper estimates the population to be influenced by China's policy of postponed retirement age and provides design strategies and suggestions in the workplace for the ageing workforce from the perspective of inclusive design.First,the literature review about western design principles and practices for the ageing workforce is conducted.It is estimated that China would face approximately 100 million elderly workers in the near future with diverse physical conditions and demands.However,the design research and practices dedicated to ageing workforce in the workplace are comparatively weak in China.Inclusive design,one of the design approaches mainly focusing on ageing problems in developed countries,as well as its theory and methodology,could act as a good reference for Chinese policymakers and designers.Then based on the concept of inclusive design,a human-centered design model is established and design suggestions from four aspects are presented.Finally,two cases are further discussed to illustrate the idea of inclusive design.展开更多
The correspondence principle is an important mathematical technique to compute the non-ageing linear viscoelastic problem as it allows to take advantage of the computational methods originally developed for the elasti...The correspondence principle is an important mathematical technique to compute the non-ageing linear viscoelastic problem as it allows to take advantage of the computational methods originally developed for the elastic case. However, the correspondence principle becomes invalid when the materials exhibit ageing. To deal with this problem, a second-order two-scale(SOTS) computational method in the time domain is presented to predict the ageing linear viscoelastic performance of composite materials with a periodic structure. First, in the time domain, the SOTS formulation for calculating the effective relaxation modulus and displacement approximate solutions of the ageing viscoelastic problem is formally derived. Error estimates of the displacement approximate solutions for SOTS method are then given. Numerical results obtained by the SOTS method are shown and compared with those by the finite element method in a very fine mesh. Both the analytical and numerical results show that the SOTS computational method is feasible and efficient to predict the ageing linear viscoelastic performance of composite materials with a periodic structure.展开更多
文摘This research considered the effect of non-natural aging on the microstructural characteristics and mechanical properties of as-cast aluminum 6063 alloys. The samples were developed through a sand casting process and machined into tensile and impact test samples before carrying out solution heat treatment at 550?C (0.83 T<sub>m</sub>) on two parts of the samples while retaining one part as the control. The two parts were further divided into sets denoted A and B and were aged at 180?C (0.27 T<sub>m</sub>) and 160?C (0.24 T<sub>m</sub>), respectively, for 12 hours. The results showed that sample A has the optimal yield strength and ultimate tensile strength of 192 and 206 MPa, respectively. Likewise, the sample gave the highest impact strength value of about 9.63 J/mm<sup>2</sup>. The observed results were supported by the optical micrograph, which revealed that the sample has evenly dispersed precipitates in its microstructure. This is deemed responsible for the observed increase in strength of the sample.
文摘The Irvingia gabonensis kernels, which have been extensively studied for their numerous virtues, including the ability to act against the accumulation of fats in the body[1], contain an oil. The aging of this oil under two different conditions of conservation was the subject of our work. One of the results was an increase in the content of long-chain carbonaceous fatty acids during aging for 11 months of storage at low temperature (6℃) and at 30℃. This behavior does not find a concordant explanation by the comparative analysis of the chemical indices. Hence, there is the need to use the Medium Infra-Red spectroscopy (MIR) which allowed to clarify the information of the saponification index, to justify the weakness of the formation of peroxides in the case of the conservation at 30℃ and to confirm the information given by the peroxide index. It also allowed to understand the formation of the long carbon chains by the “cis-trans” isomerization and the homolytic cuts which intervene within the matrix of the fat by the analysis of the number of -CH<sub>2</sub> and -CH<sub>3</sub> groups in the two conditions of conservation. This study reveals that the rapid solidification of Irvingia gabonensis oil at room temperature[2] is an advantage for its preservation at room temperature but a great weakness when the fat is stored at low temperature.
基金The authors acknowledge the financial supported by National Natural Science Foundation of China(No.52108415 and No.51808517)the National Key R&D Program of China(No.2018YFB1600200)+5 种基金the Key Technical Innovation Projects of Hubei Province(No.2019AEE023)the Key R&D Program of Hubei Province(No.2020BCB064)the State Key Laboratory of Silicate Materials for Architectures(Wuhan University of Technology)(No.SYSJJ2022-21),the Transportation Technology Project of Department of Transport of Hubei Province(No.2022-11-1-10)the European Union's Horizon 2020 Research and Innovation Programme Under the Marie Skłodowska-Curie Grant Agreement(No.101030767)the Scientific Research Fund Project of Wuhan Institute of Technology(No.K2021032)the Open Fund of National&Local Joint Engineering Laboratory of Traffic Civil Engineering Materials,Chongqing Jiaotong University(No.LHSYS-2020-004).
文摘Asphalt binder is inevitably aged by ultraviolet(UV)light during its service period.UV ageing can significantly decrease the technical properties of asphalt binder.The sensitivity of asphalt to UV ageing and thermal-oxidative ageing differs,such that the UV ageing performance cannot be determined based on the thermal-oxidative ageing performance.Previous researches mainly focused on the chemical composite and technical performance changes of asphalt binder during UV ageing,and the UV light parameters effect on the ageing rate of asphalt binder.However,the theory for characterizing and explaining the development of UV ageing depth does not get too much attentions,and the UV ageing mechanism of asphalt binder is not very clear.Therefore,it cannot guide to develop or select the good methods or anti-UV ageing additives for asphalt binders.This paper focuses on the latest researches of the mechanisms and anti-ageing methods of asphalt binders.With the increase of UV ageing time,the UV ageing of asphalt binder develops gradually from the surface to inner part.There are various methods,such as low-penetration grade asphalt,less air void ratio,UV stabilizers and UV light absorbers,that can improve the UV ageing resistance of asphalt binders.A new theory of sensitive wavelengths of asphalt UV ageing is proposed,which can enrich the basic theory of asphalt UV ageing.Depending on this theory,different wavelengths of UV light have different ageing effects on asphalt binder.The composite anti-UV ageing additives with barrier and specific absorption effects on UV light is proposed,and may have better improvement effect on the anti-UV ageing performance of asphalt binder.
基金Projects(10772156, 10672136) supported by the National Natural Science Foundation of ChinaProject(05C100) supported by the Scientific Research Fund of Education Department of Hunan Province,China
文摘The effects of stress,ageing time and ageing temperature on creep behavior of poly(methyl methacrylate) were studied.After annealing above its glass transition temperature for a period of time to eliminate the stress and thermal history,the specimens were quenched and aged at various ageing temperatures for different ageing time,and then the short-term creep tests under different stress levels were carried out at room temperature.The creep strains were modeled by means of time-ageing time equivalence and time-stress equivalence,and the master creep curves were constructed via ageing time shift factors and stress shift factors.The results indicate that the creep rate increases with stress,while decreases with ageing time,and the ageing temperature history obviously affects the creep rate.For linear viscoelastic material,the ageing shift rate is independent on imposed stress,while for nonlinear viscoelastic material,the ageing shift rate decreases with increasing stress.The unified master creep curve up to 540 d at reference state was constructed by shifting the creep curves horizontally along the logarithmic time axis to overlap each other.It is demonstrated that the time-stress equivalence,united with the time-ageing time equivalence,provides an effective accelerated characterization technique in the laboratory to evaluate the long-term creep behavior of physical ageing polymers.
文摘Increased life expectancy has led to policy interest in adding quality to years of life and in related concepts such as attitudes to ageing. Improving attitudes to ageing is regarded as one means of improving the participation and contribution of older people within society. In considering age- related attitudes in the dynamic nature of social identity, age is not just one social category that may or may not constitute a part of one’s identity. Other identities such as gender may be more salient in attitudes to ageing. The purpose of this study was to explore Norwegian gender differences in attitudes to ageing among 282 females and 200 males living in the community. Attitudes to ageing were measured using the Attitudes to Ageing Questionnaire (AAQ;Laidlaw, Power, Schmidt, & the WHOQOL-OLD Group, 2007). Both genders in this study had positive attitudes toward their ageing, in spite of acknowledging loss with problems of exclusion, making friends and talking about difficult feelings. Compared to men, women perceived ageing as a time of greater loss, however, they felt more strongly that ageing brought wisdom and that their life had made a difference. On the other hand, men felt more strongly that physical problems did not hold them back from doing what they wanted to do and believed more strongly that they passed on their experiences to others. Both genders felt that their identity was not defined by age, they didn’t feel old, aging was a privilege, and appraised the importance of exercising. Attitudes to ageing are becoming increasingly important in ageing societies. Such positive attitudes should be regarded with importance to health professionals, leaders and policy makers in planning interventions to buffer the detrimental aspects of ageing.
文摘The kinetics of the thermal decomposition for a naturally ageing ammonium perchlorate(AP) and hydroxyl-terminated-polybutadiene(HTPB) base bleed composite propellant were investigated using a differential scanning calorimetry(DSC). The naturally ageing AP/HTPB base bleed propellant samples have been stored in a sealed plastic bag at room temperature(5-25 ℃) for more than 20 years. The experimental DSC results were obtained by placing samples(each about 1.5 mg) in a sealed pan under non-isothermal condition under different heating rates, 5.0, 10.0, 15.0, 20.0 and 30.0 ℃·min^(-1). The activation energy and pre-exponential factor were estimated based on the relationship between the exothermic peak temperature and the heating rate by Ozawa and Kissinger methods, respectively. The decomposition kinetic parameters is lower the values under laboratorial aging condition.
文摘Experimental results of the investigation on the hardness of two Al-Zn-Mg alloys [Al-10.0 Zn- 4.0 Mg and Al-8.5 Zn-3.0 Mg (wt pct)] aged in the temperature range 60-310℃ for different intervals of time from 1/4 h to 168 h are presented. Both the alloys were found to show identical behaviour of hardness with ageing time. Alloy with higher Zn and Mg content had higher hardness than the alloy with lower solute content. There were three ranges of temperature in which different types of precipitates formed and affected the hardness. Some of the grain boundaries were found to migrate and precipitate free zone has been observed.
基金The present work was supported by a Croucher Innovation Award from the Croucher Foundation(to HK)a Faculty Innovation Award(FIA2017/B/01)from the Faculty of Medicine,the Chinese University of Hong Kong(CUHK)(to HK)+1 种基金the Gerald Choa Neuroscience Centre,the Margaret K.L.Cheung Research Centre for Parkinsonism Management,Faculty of Medicine,CUHK(to VCTM and HK)the Collaborative Research Fund(C6027-19GF)and the Area of Excellence Scheme(AoE/M-604/16)of the University Grants Committee of Hong Kong(to HK).
文摘Ageing is one of the greatest risk factors for neurodegenerative diseases.How the complex biological changes in ageing increase the brain’s susceptibility to neurodegeneration remains incompletely understood.Research into neurodegenerative disorders has shifted from a neuron-centric approach,to the contributing roles of age-related neurovascular and glial cell dysfunction.
基金Projects(2006BAB04A05) supported by the Eleventh Five-Year Plan of the National Key Technology Research and Development Program
文摘The fatigue properties of asphalts were investigated after various laboratory simulation ageing tests and outdoor natural exposure ultraviolet radiation ageing,by dynamic shear rheometer(DSR) time sweep fatigue test in constant strain model and a new type of specimen which was introduced to avoid the problem of adhesion failure between rotor and asphalt binder.The results show that outdoor natural exposure ageing(NEA) causes the decrease of retained fatigue life distinctly,and photodegradation caused by outdoor NEA of 1 250 μm thin films asphalt for three months,is found to be severer than pressure ageing vessel(PAV) with respects to retained fatigue life.The effect of photodegradation increases as the time of outdoor NEA increases.DSR time sweep fatigue test in constant strain indicates that the aged styrene-butadiene-styrene(SBS) modified asphalt still displays better fatigue properties than the corresponding base asphalt after ageing.
文摘North East Asian countries are facing to rapid increase in aged population ratio.The most recent values of aged population ratios are 19.5%,8.7%,and 6.9%,for Japan,Korea and China,respectively.One of the welfare services in the aged society is provision of assistive products.Electronic control systems are commonly adopted in modern assistive products and sensors are indispensable for control units.Alarm systems,such as fire alarm,smoke detectors,and gas leak detectors,have been regarded as indispensable to safety of elderly persons and persons with disability.Main application of chemical sensors in home care of elderly persons is in the field of personal care and personal medical treatment.Products for personal medical treatment include that for medical treatment in home care and that to keep elderly persons healthy.Large market is expected in the latter one.
文摘The ageing behavior of the mechanically alloyed Cu-15Ni-8Sn alloy has been studied. Compared with the alloys prepared by casting and rapid solidification, the modulation structure developed during ageing process of those prepared by mechanical alloying is finer and much more uniform, which leads to a higher peak hardness. However, their spinodal decomposition temperature are almost the same. Cold deformation prior to ageing not only accelerates the ageing process but also increases the peak hardness of the alloy.
基金supported by the China Agriculture Research System(CARS-41-Z)。
文摘The study aimed to investigate and compare the contents of carboxymethyllysine(CML)in two kinds of broilers during postmortem ageing and storage.The contents of CML in raw and boiled(100℃,30 min)broiler briskets and legs which were from white feather broilers(n=8)and yellow feather broilers(n=8)with ageing and storage at 4℃for 0-168 h were determined.Postmortem ageing and storage had a significant(P<0.05)effect on the color and A;in both boiled broilers meat.In addition,with the ageing and storage time increasing,CML content in raw white feather broiler brisket meat had no significant(P>0.05)change,while that in boiled brisket meat significantly(P<0.05)increased during 0-6 h,then decreased during 6-24 h,finally increased again.CML content in leg meat increased significantly(P<0.05)with the ageing and storage time prolonging.But postmortem ageing and storage had no significant(P>0.05)effect on the CML contents in raw/boiled yellow feather broilers.Meanwhile,CML contents in white feather broilers were much higher than that in yellow feather broilers.Thus,white feather broilers can be selected as the research object to study the mechanism of ageing and storage on CML content in the postmortem broiler in the future.
文摘The paper provides a general overview of chemical processes leading to the degradation of oil-paper insulation in oil-immersed electrical current transformers. Previous knowledge available in literature is complemented by new results placing a specific emphasis on the physicochemical factors which affect the copper release in the insulation oil and the oil oxidation kinetics. It is demonstrated that various ageing processes interact with each other, with one or another process dominating under specific conditions. Comprehensive but disjoint studies focusing on separate sub-processes may produce rather misleading results, and occasionally, lie behind rather irrelevant quality demands imposed on the insulating liquids.
文摘Spherulitic morphology of pure poly lactic acid (PLLA) PLLA have investigated after thermal annealing. The morphology of spherulite of pure poly lactic acid (PLLA) PLLA have investigated after thermal annealing. The effect of both annealing temperature and crystallization temperature on the formation of cracks was described by polarized optical microscope (POM). Non banded spherulite (fibrils) with cracks was detected in PLLA film after annealing at 160°C (180 min.) and isothermal crystallization temperatures at 140°C and 150°C. With increasing temperature after annealing treatment the size of spherulite is increased and more cracks are formed. The maximum growth rate of spherulites was found at 130°C. The physical ageing was carried out by annealing the PLLA sample at room temperature for several annealing time (ta) from 0 h to 720 h. The enthalpy relaxation has been studied by differential scanning calorimetry (DSC) through analysis of the endothermic peak of glass transition temperature, which increased and shifted towards higher temperature as the annealing time increased.
文摘Poor adventitious root formation is a major obstacle in micropropagation and in conventional propagation. The effects of LaCl3 on root growth and deferring the root ageing of peach plantlet in vitro were investigated. The results show that the optimum concentration of LaCl3 （2.5 μmol·L -1） in the rooted medium can significantly increase the rooting rate, the root length and the fresh weight, promote the activities of superoxide dismutase （SOD）; catalase （CAT） and peroxidase （POD） and decrease the production rate of O2 ·-, the malondialdehyde （MDA） contents and the plasma membrane permeability. There are important theory meaning and practical value in applying LaCl3 in the rooting medium to raise the rate of rooting and transplant for stone fruit tree.
基金Supported by the Shanghai Education Science Research Program(C17067)
文摘This paper estimates the population to be influenced by China's policy of postponed retirement age and provides design strategies and suggestions in the workplace for the ageing workforce from the perspective of inclusive design.First,the literature review about western design principles and practices for the ageing workforce is conducted.It is estimated that China would face approximately 100 million elderly workers in the near future with diverse physical conditions and demands.However,the design research and practices dedicated to ageing workforce in the workplace are comparatively weak in China.Inclusive design,one of the design approaches mainly focusing on ageing problems in developed countries,as well as its theory and methodology,could act as a good reference for Chinese policymakers and designers.Then based on the concept of inclusive design,a human-centered design model is established and design suggestions from four aspects are presented.Finally,two cases are further discussed to illustrate the idea of inclusive design.
基金Project supported by the National Natural Science Foundation of China(No.11471262)
文摘The correspondence principle is an important mathematical technique to compute the non-ageing linear viscoelastic problem as it allows to take advantage of the computational methods originally developed for the elastic case. However, the correspondence principle becomes invalid when the materials exhibit ageing. To deal with this problem, a second-order two-scale(SOTS) computational method in the time domain is presented to predict the ageing linear viscoelastic performance of composite materials with a periodic structure. First, in the time domain, the SOTS formulation for calculating the effective relaxation modulus and displacement approximate solutions of the ageing viscoelastic problem is formally derived. Error estimates of the displacement approximate solutions for SOTS method are then given. Numerical results obtained by the SOTS method are shown and compared with those by the finite element method in a very fine mesh. Both the analytical and numerical results show that the SOTS computational method is feasible and efficient to predict the ageing linear viscoelastic performance of composite materials with a periodic structure.
