Layered double hydroxides(LDHs) with the physical property of high ultraviolet(UV)reflectance were used to enhance the anti-UV aging performance of bitumen. In view of the poor compatibility of LDHs with bitumen, thre...Layered double hydroxides(LDHs) with the physical property of high ultraviolet(UV)reflectance were used to enhance the anti-UV aging performance of bitumen. In view of the poor compatibility of LDHs with bitumen, three organic anions, namely, sodium dodecyl benzenesulfonate(SDBS), sodium dodecyl sulfate(SDS) and sodium dodecyl sulfonate(SDSO), were used as modifiers to prepare organic LDHs(OCLDHs) through regeneration process, and the crystal structure, chemical composition, morphological feature and UV shielding capability of synthesized OCLDHs were analyzed. Then the OCLDHs were added into bitumen to evaluate the storage stability and anti-UV aging property of OCLDHs/bitumen composites.The results show that the organic anions are inserted into the interlayers of LDHs, the intercalation expands the interlayer distance of LDHs, makes the particle shapes become more irregular and complicated, and enhances the absorption ability within the range from 200 to 300 nm while has little influence on the UV reflection ability.Result of high temperature storage stability indicates the organic modification ameliorates the compatibility of LDHs with bitumen. Compared with LDHs, OCLDHs decrease the deteriorations of bitumen’s properties during UV exposure test, exhibiting better effect in enhancing anti-UV aging performance of bitumen. Furthermore,among the three OCLDHs, LDHs intercalated by SDBS exhibit the most effective improvement due to the best compatibility with bitumen and comparatively good UV shielding effect.展开更多
A study was conducted to better understand how different parameters, namely, regression aging time and regression aging temperature, affect the creep aging properties, i.e., the creep deformation and performance of Al...A study was conducted to better understand how different parameters, namely, regression aging time and regression aging temperature, affect the creep aging properties, i.e., the creep deformation and performance of Al-Zn-MgCu alloy during regressive reaging. The corresponding creep strain and mechanical properties of samples were studied by conducting creep tests and uniaxial tensile tests. The electrical conductivity was measured using an eddy-current conductivity meter. The microstructures were observed by transmission electron microscopy(TEM). With the increase in regression aging time, the steady creep strain first increased and then decreased, and reached the maximum at 45 min.The steady creep strain increased with the increase in regression aging temperature, and reached the maximum at 200 ℃.The level of steady creep strain was determined by precipitation and dislocation recovery. Creep aging strengthens 7B50-RRA treated with regression aging time at 190 ℃ for 10 min, and the difference in the mechanical properties of alloy becomes smaller. The diffusion of solute atoms reduces the scattering of electrons, leading to a significant improvement in electrical conductivity and stress corrosion cracking(SCC) resistance after creep aging. The findings of this study could help in the application of creep aging forming(CAF) technology in Al-Zn-Mg-Cu alloy under RRA treatment.展开更多
Porous silver-modified ZnO microrods photocatalysts were synthesized through direct thermal decomposition of the Ag-doped zinctartrate precursor,which was prepared by homogeneous precipitation method at 80 °C for...Porous silver-modified ZnO microrods photocatalysts were synthesized through direct thermal decomposition of the Ag-doped zinctartrate precursor,which was prepared by homogeneous precipitation method at 80 °C for 2 h.The obtained samples were characterized by XRD,FTIR,TG？DTA and UV-VIS absorption spectroscopy.The photocatalytic activity of the as-prepared porous Ag/ZnO microrods was tested with the photocatalytic degradation of methyl orange.The results indicate that doping Ag greatly improves the photocatalytic efficiency of ZnO and 3% Ag-doped（mole fraction） ZnO porous microrod photocatalyst exhibits the highest photocatalytic decolorization efficiency,leading to as much as 80% reduction of MO concentration in 120 min.Moreover,the 3% Ag-doped porous microrods also possess higher photocatalytic activity under the real sunlight irradiation.展开更多
High-performance concrete （HPC） is stronger and more durable than conventional concrete. However, shrinkage and shrinkage cracking are common phenomena in HPC, especially early-age cracking. This study assessed earl...High-performance concrete （HPC） is stronger and more durable than conventional concrete. However, shrinkage and shrinkage cracking are common phenomena in HPC, especially early-age cracking. This study assessed early-age cracking of HPC for two mixtures using restrained ring tests. The two mixtures were produced with water/binder mass ratio （mw/mB） of 0.22 and 0.40, respectively. The results show that, with greater steel thickness, the higher degree of restraint resulted in a higher interface pressure and earlier cracking. With steel thickness of 6 mm, 19 mm, and 30 mm, the age of cracking were, respectively, 12 days, 8 days, and 5.4 days with the mw/mB = 0.22 mixture; and 22.5 days, 12.6 days, and 7.1 days with the mw/mB= 0.40 mixture. Cases of the same steel thickness show that the ring specimens with a thicker concrete wall crack later. With the mw/mB = 0.22 mixture, concrete walls with thicknesses of 37.5 mm, 75 mm, and 112.5 mm cracked at 3.4 days, 8.0 days, and 9.8 days, respectively; with the mw/mB = 0.40 mixture, the ages of cracking were 7.1 days, 12.6 days, and 16.0 days, respectively.展开更多
Diesel soot subjected to high exhaust temperature suffers from thermal ageing,which is difficult to be removed by regeneration process.Based on the thermogravimetric(TG)analysis and images by high resolution transmiss...Diesel soot subjected to high exhaust temperature suffers from thermal ageing,which is difficult to be removed by regeneration process.Based on the thermogravimetric(TG)analysis and images by high resolution transmission electron microscope(HRTEM),effects of thermal ageing temperature,ageing time and oxygen concentration on oxidation characteristic of soot are investigated.The activation energy of soot increases with the increase of ageing temperature and oxygen concentration.The activation energy increases rapidly when the ageing time is less than 45 min,and then it keeps in a value of 157 kJ/mol when the ageing time is between 45 and 60 min.Compared to the soot without thermal ageing,the shape of ageing soot particles presents shorter diameter and more regular circle by observing soot nanostructure.With the increase of ageing temperature,ageing time and oxygen concentration,the more stable structure of“shell and core”is shown in the basic carbon.The soot has an increased fringe length,decreased tortuosity and separation distance after thermal ageing process,which leads to the deepening of the disorder degree of soot nanostructures and reduction of soot oxidation activity.Consequently,the thermal ageing process should be avoided in order to optimize the active regeneration strategy.展开更多
This study uses a building energy performance simulation to investigate the impact of predicted climate warming and the additional issue of building ageing on the energy performance for a library in Turin,Italy.The cl...This study uses a building energy performance simulation to investigate the impact of predicted climate warming and the additional issue of building ageing on the energy performance for a library in Turin,Italy.The climate and ageing factors were modelled individually and then integrated together for several decades.Results from the climate-only simulation showed a decrease in thebuilding heating energy usage which outweighed the increase in the on-site cooling energy demand occurring in a warming scenario.The study revealed a high sensitivity of energy performance to building ageing,in particular due to HVAC(Heating,Ventilation and Air Conditioning) equipment efficiency degradation.Building ageing was seen to negatively affect the energy performance as it induced a further increase of the cooling energy usage in a warming climate,while it also counteracted the reduction of the heating energy usage resulting from warming.Simulations on the combination of mitigation techniques showed a number of potentially retrofit measures that would be beneficial for buildings to avoid an increase in the cooling energy usage due to climate warming.The combination of these retrofit techniques showed a potential decrease of 87.3% in the final cooling energy usage for the considered building.展开更多
Ag3PO4 microcrystals with highly enhanced visible light photocatalytic activity are prepared by a facile and simple solid state reaction at room temperature. The composition, morphology and optical properties of the a...Ag3PO4 microcrystals with highly enhanced visible light photocatalytic activity are prepared by a facile and simple solid state reaction at room temperature. The composition, morphology and optical properties of the asprepared Ag3PO4 microcrystMs are characterized by x-ray diffraction, scanning electron microscopy and UV-vis diffuse reflectance spectra. The photocatalytie properties of Ag3PO4 are investigated by the degradation of both methylene blue and methyl orange dyes under visible light irradiation. The as-prepared Ag3PO4 microcrystals possess high photocatalytic oxygen production with the rate of 673μmolh-1g-1. Moreover, the as-prepared Ag3PO4 microcrystals show an enhanced photoelectrochemistry performance under irradiation of visible light.展开更多
Considering the insulators ageing in a mixture of PVC and dye, set following operating conditions and time to ensure proper operation and perfect safety of industrial installations using insulated conductors. The resu...Considering the insulators ageing in a mixture of PVC and dye, set following operating conditions and time to ensure proper operation and perfect safety of industrial installations using insulated conductors. The results showed that the insulation carried out by the L.C main office was a good quality (on thermal aspect), because the resistance of the insulation is so high (i.e. 3940 Mega Ohms under normal conditions). The results showed a lifespan of 50 years at a temperature of 40°C (close to ambient temperature), plus minus 33 years at a temperature of 70°C;plus minus 22 years at a temperature of 100°C and 12 years at a temperature of 160°C. Furthermore, information on chemical attack, the results showed that PVC cables have poor resistance to sulfuric acid attack (having a pH of 1.5 and a density of 1.84 g/cm<sup>3</sup>). LC/Gecamines is able to produce locally a good quality of electrical cables.展开更多
D-galactose has been widely used in aging research because of its efficacy in inducing senescence and accelerating aging in animal models. The present study investigated the benefits of exercise for preventing neurode...D-galactose has been widely used in aging research because of its efficacy in inducing senescence and accelerating aging in animal models. The present study investigated the benefits of exercise for preventing neurodegeneration, such as synaptic plasticity, spatial learning and memory abilities, in mouse models of aging. D-galactose-induced aging mice were administered daily subcutaneous injections of D-galactose at the base of the neck for 10 consecutive weeks. Then, the mice were subjected to exercise training by running on a treadmill for 6 days a week. Shortened escape latency in a Morris water maze test indicated that exercise improved learning and memory in aging mice. The ameliorative changes were likely induced by an upregulation of Bcl-2 and brain-derived neurotrophic factor, the repression of apoptosis factors such as Fas and Bax, and an increase in the activity of glucose transporters-1 and 4. The data suggest moderate exercise may retard or inhibit neurodegeneration in D-galactose-induced aging mice.展开更多
This research sought to improve the properties of SAC305 solder joints by the addition of 1 and 2 wt.%Bi.The effects of bismuth doping on the microstructure,thermal properties,and mechanical performance of the SAC305−...This research sought to improve the properties of SAC305 solder joints by the addition of 1 and 2 wt.%Bi.The effects of bismuth doping on the microstructure,thermal properties,and mechanical performance of the SAC305−xBiCu solder joints were investigated.Bi-doping modified the microstructure of the solder joints by refining the primaryβ-Sn and eutectic phases.Bi-doping below 2 wt.%dissolved in theβ-Sn matrix and formed a solid solution,whereas Bi additions equal to or greater than 2 wt.%formed Bi precipitates in theβ-Sn matrix.Solid solution strengthening and precipitation strengthening mechanisms in theβ-Sn matrix increased the ultimate tensile strength and microhardness of the alloy from 35.7 MPa and 12.6 HV to 55.3 MPa and 20.8 HV,respectively,but elongation decreased from 24.6%to 16.1%.The fracture surface of a solder joint containing 2 wt.%Bi was typical of a brittle failure rather than a ductile failure.The interfacial layer of all solder joints comprised two parallel IMC layers:a layer of Cu6Sn5 and a layer of Cu3Sn.The interfacial layer was thinner and the shear strength was greater in SAC305−xBiCu joints than in SAC305Cu solder joints.Therefore,small addition of Bi refined microstructure,reduced melting temperature and improved the mechanical performance of SAC305Cu solder joints.展开更多
Because of the different ways in which contact materials work, the basic requirements for silver metal oxide contact materials are different. They are anti-welded and anti-erosion when closed, anti-erosion when broken...Because of the different ways in which contact materials work, the basic requirements for silver metal oxide contact materials are different. They are anti-welded and anti-erosion when closed, anti-erosion when broken, and arc easily moved and have smaller contact resistance. In this paper, La2O3 is used as a stable oxide in contact material to replace CdO. A new type of Ag/SnO2-La2O3-Bi2O3 contact material is first obtained through using powder metallurgical method. Then electrical contact material parameter tester is used to test the electrical contact performance of the contact material. Through experiments, the arcing voltage and current curves, arcing energy curves, fusion power curves while broken and contact resistance while closed were obtained. Analysis of the results showed that the addition of La2O3 makes the contact material have the following advantages: smaller electrical wear, smaller arc energy, smaller contact resistance and arc is more easily extinguished.展开更多
BACKGROUND： Prophylactic dietary restriction （DR）, whether lifelong or started in adulthood,retards the aging process and attenuates cognitive decline in rodents. However, whether the anti-aging and neuroprotective...BACKGROUND： Prophylactic dietary restriction （DR）, whether lifelong or started in adulthood,retards the aging process and attenuates cognitive decline in rodents. However, whether the anti-aging and neuroprotective efficacy of DR initiate late in life or accompany the aging process remains unclear.OBJECTIVE： The present study sought to： （1） determine if DR could protect against behavioral decline in mice when implemented during the aging process induced by D-galactose and （2） examine neuronal apoptosis in these aged brains and whether DR could block apoptosis.DESIGN, TIME AND SETTING： The randomized controlled animal study. The experiment was performed at the Experimental Animal Center of Capital Medical University and the Laboratory Center of School of Public Health of Captial Medical University of China from April 2006 to October 2007.MATERIALS： D-galactose （D-gal） was purchased from Beijing Chemical-Regent Company （Beijing, China）. Terminal transferase dUTP nick end labeling （TUNEL） detection kit was obtained from Roche, Germany. Assay kits for antioxidant enzyme activities and malondialdehyde contents were purchased from Jiancheng Institute of Biotechnology （Nanjing, China）. Morris water maze （Friends Honesty Life Sciences Co. Ltd., Hong Kong, China） and Flow Cytometry （Coulter, USA） were used in this study.METHODS： A total of 40 male Institute of Cancer Research （lCR） mice, 3 months old, were equally and randomly divided into D-gal treatment, DR treatment, D-gal ＋ DR treatment and normal control groups, and were then randomly assigned to one of two feeding regimens： ad libitum access to food or DR which received a 70% amount of daily food intake as that by ad libitum fed mice. There were two replicates per feeding regimen and mice were fed for 10 weeks,with or without a daily subcutaneous injection of D-gal at 100 mg/kg.MAIN OUTCOME MEASURES： Animals＇ spatial learning and memory performance were tested in the Morris water maze. Neuronal apoptosis rates were evaluated by Annexin V/flow cytometry assay and TUNEL assay. Lipid peroxidation levels and antioxidant defense capacity of the brain were measured using testing kits.RESULTS： DR markedly reduced the prolonged escape latency of D-gal mice in the water maze test （P〈0.01）. Annexin V and TUNEL assays showed that the D-gal mice had a significant higher percentage of neuronal apoptosis compared with normal control mice （P〈0.05）, and that DR treatment markedly decreased this apoptotic cell death （P〈0.05）. DR also reversed the decline of total superoxide dismutase and glutathione peroxidase activities and the increase of malondialdehyde levels in the brain of D-gal mice （P〈0.05, respectively）.CONCLUSION： DR reduces the impact of D-gal-induced brain aging in mice and can reverse performance decline and neurobiochemical impairments. These results demonstrate that implementation of DR in conditions of chronic oxidative stress can be neuroprotective, and that senium DR can be beneficial for healthy aging.展开更多
Objective:To examine the impact of a 6-week endurance training on red blood cell(RBC)aging and deformability of healthy participants to detect possible improved hemorheological and performance-related adaptations.Meth...Objective:To examine the impact of a 6-week endurance training on red blood cell(RBC)aging and deformability of healthy participants to detect possible improved hemorheological and performance-related adaptations.Methods:A total of 31 participants(17 females and 14 males)performed a 6-week moderate training protocol(three 1-h running sessions per week at 70%of maximal heart rate).Blood was sampled before and after the training.RBCs from each participant were fractioned according to density and age into 4 RBC subfractions.Subfractions were examined for changes of RBC properties,including aging distribution,RBC deformability,RBC microparticles,and phosphatidylserine concentrations.RBC and plasma nitrite levels were measured as indicators of nitric oxide metabolism.Results:Aerobic performance,peak oxygen consumption,ventilatory thresholds,velocity at the aerobic-anaerobic threshold,and lactate at exhaustion improved after training.The relative amount of both young RBCs and old RBCs increased,and the amount of the main RBC fraction decreased.Phosphatidylserine externalization and RBC-derived microparticles decreased.Overall deformability expressed as shear stress required to achieve half-maximum deformation to theoretical maximal elongation index at infinite shear stress improved in unfractioned RBCs(p<0.001).Nitrite decreased in total(p=0.001),young(p<0.001),main(p<0.001),and old(p=0.020)aged RBCs and in plasma(p=0.002),but not in very old RBCs.Conclusion:These results indicate that non-endurance-trained healthy participants benefit from a regular moderate running training program because performance-related parameters improve and a younger RBC population with improved RBC properties is induced,which might support oxygen supply in the microcirculation.展开更多
Organic-inorganic nanojunctions can result in a selective scattering of charge carrier depending on their energy, which leads to a simultaneous increase in the Seebeck coefficient S and the power factor. In this work,...Organic-inorganic nanojunctions can result in a selective scattering of charge carrier depending on their energy, which leads to a simultaneous increase in the Seebeck coefficient S and the power factor. In this work, the nanojunction is successfully employed at the organic-inorganic semiconductor interface of polyparaphenylene （PPP） and Zn1-xAgxO nanoparticles through the sol-gel method. The presence of nanoinclusions PPP in Zno.gAgoa 0 matrix is found to be effective in improving the figure of merit （ZT） by the dual effects of an increase in the power factor consistent with the heterojunetion effect and a reduction in thermal conductivity. Zno.gAgo.10/0.1 wt% PPP exhibits a maximum figure of merit, i.e., ZT= 0.22.展开更多
Sulfur content is one of the fuel properties to be monitored. Sulfur dioxide, the major product derived from organic sulfur compounds in the exhaust gas emissions, is a poison to the three-way catalysts (TWC). A gas m...Sulfur content is one of the fuel properties to be monitored. Sulfur dioxide, the major product derived from organic sulfur compounds in the exhaust gas emissions, is a poison to the three-way catalysts (TWC). A gas mixture was applied to simulate the exhaust gases used in the TWC aging procedure tests. Two types of the TWC, REX-IIC and REX-IID, were tested in this study. The performance of both TWC's before and after the 100-hour sulfur aging program was compared. It was concluded that the Pt component in the TWC was apt to be poisoned by sulfur much easily than Rh. The performance of the REX-IID catalyst was generally better than that of the REX-IIC catalyst.展开更多
基金Funded by the National Natural Science Foundation of China(No.51708121)the National Basic Research Program of China(973 Program)(No.2014CB932104)the Educational Research Projects for Young and Middle-Aged Teachers of Education Department of Fujian Province(No.JAT170067)
文摘Layered double hydroxides(LDHs) with the physical property of high ultraviolet(UV)reflectance were used to enhance the anti-UV aging performance of bitumen. In view of the poor compatibility of LDHs with bitumen, three organic anions, namely, sodium dodecyl benzenesulfonate(SDBS), sodium dodecyl sulfate(SDS) and sodium dodecyl sulfonate(SDSO), were used as modifiers to prepare organic LDHs(OCLDHs) through regeneration process, and the crystal structure, chemical composition, morphological feature and UV shielding capability of synthesized OCLDHs were analyzed. Then the OCLDHs were added into bitumen to evaluate the storage stability and anti-UV aging property of OCLDHs/bitumen composites.The results show that the organic anions are inserted into the interlayers of LDHs, the intercalation expands the interlayer distance of LDHs, makes the particle shapes become more irregular and complicated, and enhances the absorption ability within the range from 200 to 300 nm while has little influence on the UV reflection ability.Result of high temperature storage stability indicates the organic modification ameliorates the compatibility of LDHs with bitumen. Compared with LDHs, OCLDHs decrease the deteriorations of bitumen’s properties during UV exposure test, exhibiting better effect in enhancing anti-UV aging performance of bitumen. Furthermore,among the three OCLDHs, LDHs intercalated by SDBS exhibit the most effective improvement due to the best compatibility with bitumen and comparatively good UV shielding effect.
基金Project(2017YFB0306300) supported by the National key R&D Program of ChinaProjects(51675538, 51905551)supported by the National Natural Science Foundation of ChinaProject(ZZYJKT2019-11) supported by Free Exploration Project of State Key Laboratory of High performance Complex Manufacturing,China。
文摘A study was conducted to better understand how different parameters, namely, regression aging time and regression aging temperature, affect the creep aging properties, i.e., the creep deformation and performance of Al-Zn-MgCu alloy during regressive reaging. The corresponding creep strain and mechanical properties of samples were studied by conducting creep tests and uniaxial tensile tests. The electrical conductivity was measured using an eddy-current conductivity meter. The microstructures were observed by transmission electron microscopy(TEM). With the increase in regression aging time, the steady creep strain first increased and then decreased, and reached the maximum at 45 min.The steady creep strain increased with the increase in regression aging temperature, and reached the maximum at 200 ℃.The level of steady creep strain was determined by precipitation and dislocation recovery. Creep aging strengthens 7B50-RRA treated with regression aging time at 190 ℃ for 10 min, and the difference in the mechanical properties of alloy becomes smaller. The diffusion of solute atoms reduces the scattering of electrons, leading to a significant improvement in electrical conductivity and stress corrosion cracking(SCC) resistance after creep aging. The findings of this study could help in the application of creep aging forming(CAF) technology in Al-Zn-Mg-Cu alloy under RRA treatment.
基金Project (20907001) supported by the National Natural Science Foundation of ChinaProject (KJ2010A336) supported by the University Natural Science Research Project of Anhui Province,ChinaProject (KJ2009A010Z) supported by the Educational Commission of Anhui Province,China
文摘Porous silver-modified ZnO microrods photocatalysts were synthesized through direct thermal decomposition of the Ag-doped zinctartrate precursor,which was prepared by homogeneous precipitation method at 80 °C for 2 h.The obtained samples were characterized by XRD,FTIR,TG？DTA and UV-VIS absorption spectroscopy.The photocatalytic activity of the as-prepared porous Ag/ZnO microrods was tested with the photocatalytic degradation of methyl orange.The results indicate that doping Ag greatly improves the photocatalytic efficiency of ZnO and 3% Ag-doped（mole fraction） ZnO porous microrod photocatalyst exhibits the highest photocatalytic decolorization efficiency,leading to as much as 80% reduction of MO concentration in 120 min.Moreover,the 3% Ag-doped porous microrods also possess higher photocatalytic activity under the real sunlight irradiation.
文摘High-performance concrete （HPC） is stronger and more durable than conventional concrete. However, shrinkage and shrinkage cracking are common phenomena in HPC, especially early-age cracking. This study assessed early-age cracking of HPC for two mixtures using restrained ring tests. The two mixtures were produced with water/binder mass ratio （mw/mB） of 0.22 and 0.40, respectively. The results show that, with greater steel thickness, the higher degree of restraint resulted in a higher interface pressure and earlier cracking. With steel thickness of 6 mm, 19 mm, and 30 mm, the age of cracking were, respectively, 12 days, 8 days, and 5.4 days with the mw/mB = 0.22 mixture; and 22.5 days, 12.6 days, and 7.1 days with the mw/mB= 0.40 mixture. Cases of the same steel thickness show that the ring specimens with a thicker concrete wall crack later. With the mw/mB = 0.22 mixture, concrete walls with thicknesses of 37.5 mm, 75 mm, and 112.5 mm cracked at 3.4 days, 8.0 days, and 9.8 days, respectively; with the mw/mB = 0.40 mixture, the ages of cracking were 7.1 days, 12.6 days, and 16.0 days, respectively.
基金Project(51676167)supported by the National Natural Science Foundation of ChinaProject(17TD0035)supported by the Sichuan Provincial Scientific Research Innovation Team Program,ChinaProjects(2017TD0026,2015TD0021)supported by Science&Technology Department of Sichuan Province,China。
文摘Diesel soot subjected to high exhaust temperature suffers from thermal ageing,which is difficult to be removed by regeneration process.Based on the thermogravimetric(TG)analysis and images by high resolution transmission electron microscope(HRTEM),effects of thermal ageing temperature,ageing time and oxygen concentration on oxidation characteristic of soot are investigated.The activation energy of soot increases with the increase of ageing temperature and oxygen concentration.The activation energy increases rapidly when the ageing time is less than 45 min,and then it keeps in a value of 157 kJ/mol when the ageing time is between 45 and 60 min.Compared to the soot without thermal ageing,the shape of ageing soot particles presents shorter diameter and more regular circle by observing soot nanostructure.With the increase of ageing temperature,ageing time and oxygen concentration,the more stable structure of“shell and core”is shown in the basic carbon.The soot has an increased fringe length,decreased tortuosity and separation distance after thermal ageing process,which leads to the deepening of the disorder degree of soot nanostructures and reduction of soot oxidation activity.Consequently,the thermal ageing process should be avoided in order to optimize the active regeneration strategy.
文摘This study uses a building energy performance simulation to investigate the impact of predicted climate warming and the additional issue of building ageing on the energy performance for a library in Turin,Italy.The climate and ageing factors were modelled individually and then integrated together for several decades.Results from the climate-only simulation showed a decrease in thebuilding heating energy usage which outweighed the increase in the on-site cooling energy demand occurring in a warming scenario.The study revealed a high sensitivity of energy performance to building ageing,in particular due to HVAC(Heating,Ventilation and Air Conditioning) equipment efficiency degradation.Building ageing was seen to negatively affect the energy performance as it induced a further increase of the cooling energy usage in a warming climate,while it also counteracted the reduction of the heating energy usage resulting from warming.Simulations on the combination of mitigation techniques showed a number of potentially retrofit measures that would be beneficial for buildings to avoid an increase in the cooling energy usage due to climate warming.The combination of these retrofit techniques showed a potential decrease of 87.3% in the final cooling energy usage for the considered building.
基金Supported by the Beijing Higher Education Young Elite Teacher Project under Grant No YETP1297the Fundamental Research Funds for the Central Universities under Grant No 2014MDLXYZY05+1 种基金the Undergraduate Innovative Test Program of China under Grant Nos GCCX2015110009 and BEIJ2015110024the National Natural Science Foundation of China under Grant Nos11074312 and 11374377
文摘Ag3PO4 microcrystals with highly enhanced visible light photocatalytic activity are prepared by a facile and simple solid state reaction at room temperature. The composition, morphology and optical properties of the asprepared Ag3PO4 microcrystMs are characterized by x-ray diffraction, scanning electron microscopy and UV-vis diffuse reflectance spectra. The photocatalytie properties of Ag3PO4 are investigated by the degradation of both methylene blue and methyl orange dyes under visible light irradiation. The as-prepared Ag3PO4 microcrystals possess high photocatalytic oxygen production with the rate of 673μmolh-1g-1. Moreover, the as-prepared Ag3PO4 microcrystals show an enhanced photoelectrochemistry performance under irradiation of visible light.
文摘Considering the insulators ageing in a mixture of PVC and dye, set following operating conditions and time to ensure proper operation and perfect safety of industrial installations using insulated conductors. The results showed that the insulation carried out by the L.C main office was a good quality (on thermal aspect), because the resistance of the insulation is so high (i.e. 3940 Mega Ohms under normal conditions). The results showed a lifespan of 50 years at a temperature of 40°C (close to ambient temperature), plus minus 33 years at a temperature of 70°C;plus minus 22 years at a temperature of 100°C and 12 years at a temperature of 160°C. Furthermore, information on chemical attack, the results showed that PVC cables have poor resistance to sulfuric acid attack (having a pH of 1.5 and a density of 1.84 g/cm<sup>3</sup>). LC/Gecamines is able to produce locally a good quality of electrical cables.
基金supported by the National Natural Science Foundation of China,No.81373020Beijing Natural Science Foundation of China,No.7112014+1 种基金a grant from the Science and Technology Development Project of Beijing Municipal Education Commission of China,No.KM201110025014a grant from the Beijing Municipal Science and Technology Project of China,No.Z131107002213071
文摘D-galactose has been widely used in aging research because of its efficacy in inducing senescence and accelerating aging in animal models. The present study investigated the benefits of exercise for preventing neurodegeneration, such as synaptic plasticity, spatial learning and memory abilities, in mouse models of aging. D-galactose-induced aging mice were administered daily subcutaneous injections of D-galactose at the base of the neck for 10 consecutive weeks. Then, the mice were subjected to exercise training by running on a treadmill for 6 days a week. Shortened escape latency in a Morris water maze test indicated that exercise improved learning and memory in aging mice. The ameliorative changes were likely induced by an upregulation of Bcl-2 and brain-derived neurotrophic factor, the repression of apoptosis factors such as Fas and Bax, and an increase in the activity of glucose transporters-1 and 4. The data suggest moderate exercise may retard or inhibit neurodegeneration in D-galactose-induced aging mice.
文摘This research sought to improve the properties of SAC305 solder joints by the addition of 1 and 2 wt.%Bi.The effects of bismuth doping on the microstructure,thermal properties,and mechanical performance of the SAC305−xBiCu solder joints were investigated.Bi-doping modified the microstructure of the solder joints by refining the primaryβ-Sn and eutectic phases.Bi-doping below 2 wt.%dissolved in theβ-Sn matrix and formed a solid solution,whereas Bi additions equal to or greater than 2 wt.%formed Bi precipitates in theβ-Sn matrix.Solid solution strengthening and precipitation strengthening mechanisms in theβ-Sn matrix increased the ultimate tensile strength and microhardness of the alloy from 35.7 MPa and 12.6 HV to 55.3 MPa and 20.8 HV,respectively,but elongation decreased from 24.6%to 16.1%.The fracture surface of a solder joint containing 2 wt.%Bi was typical of a brittle failure rather than a ductile failure.The interfacial layer of all solder joints comprised two parallel IMC layers:a layer of Cu6Sn5 and a layer of Cu3Sn.The interfacial layer was thinner and the shear strength was greater in SAC305−xBiCu joints than in SAC305Cu solder joints.Therefore,small addition of Bi refined microstructure,reduced melting temperature and improved the mechanical performance of SAC305Cu solder joints.
基金Project (No. 502048) supported by the Natural Science Foundation of Hebei Province, China
文摘Because of the different ways in which contact materials work, the basic requirements for silver metal oxide contact materials are different. They are anti-welded and anti-erosion when closed, anti-erosion when broken, and arc easily moved and have smaller contact resistance. In this paper, La2O3 is used as a stable oxide in contact material to replace CdO. A new type of Ag/SnO2-La2O3-Bi2O3 contact material is first obtained through using powder metallurgical method. Then electrical contact material parameter tester is used to test the electrical contact performance of the contact material. Through experiments, the arcing voltage and current curves, arcing energy curves, fusion power curves while broken and contact resistance while closed were obtained. Analysis of the results showed that the addition of La2O3 makes the contact material have the following advantages: smaller electrical wear, smaller arc energy, smaller contact resistance and arc is more easily extinguished.
文摘BACKGROUND： Prophylactic dietary restriction （DR）, whether lifelong or started in adulthood,retards the aging process and attenuates cognitive decline in rodents. However, whether the anti-aging and neuroprotective efficacy of DR initiate late in life or accompany the aging process remains unclear.OBJECTIVE： The present study sought to： （1） determine if DR could protect against behavioral decline in mice when implemented during the aging process induced by D-galactose and （2） examine neuronal apoptosis in these aged brains and whether DR could block apoptosis.DESIGN, TIME AND SETTING： The randomized controlled animal study. The experiment was performed at the Experimental Animal Center of Capital Medical University and the Laboratory Center of School of Public Health of Captial Medical University of China from April 2006 to October 2007.MATERIALS： D-galactose （D-gal） was purchased from Beijing Chemical-Regent Company （Beijing, China）. Terminal transferase dUTP nick end labeling （TUNEL） detection kit was obtained from Roche, Germany. Assay kits for antioxidant enzyme activities and malondialdehyde contents were purchased from Jiancheng Institute of Biotechnology （Nanjing, China）. Morris water maze （Friends Honesty Life Sciences Co. Ltd., Hong Kong, China） and Flow Cytometry （Coulter, USA） were used in this study.METHODS： A total of 40 male Institute of Cancer Research （lCR） mice, 3 months old, were equally and randomly divided into D-gal treatment, DR treatment, D-gal ＋ DR treatment and normal control groups, and were then randomly assigned to one of two feeding regimens： ad libitum access to food or DR which received a 70% amount of daily food intake as that by ad libitum fed mice. There were two replicates per feeding regimen and mice were fed for 10 weeks,with or without a daily subcutaneous injection of D-gal at 100 mg/kg.MAIN OUTCOME MEASURES： Animals＇ spatial learning and memory performance were tested in the Morris water maze. Neuronal apoptosis rates were evaluated by Annexin V/flow cytometry assay and TUNEL assay. Lipid peroxidation levels and antioxidant defense capacity of the brain were measured using testing kits.RESULTS： DR markedly reduced the prolonged escape latency of D-gal mice in the water maze test （P〈0.01）. Annexin V and TUNEL assays showed that the D-gal mice had a significant higher percentage of neuronal apoptosis compared with normal control mice （P〈0.05）, and that DR treatment markedly decreased this apoptotic cell death （P〈0.05）. DR also reversed the decline of total superoxide dismutase and glutathione peroxidase activities and the increase of malondialdehyde levels in the brain of D-gal mice （P〈0.05, respectively）.CONCLUSION： DR reduces the impact of D-gal-induced brain aging in mice and can reverse performance decline and neurobiochemical impairments. These results demonstrate that implementation of DR in conditions of chronic oxidative stress can be neuroprotective, and that senium DR can be beneficial for healthy aging.
基金supported by the Hochschulinterne Forschungsforderung(HIF)of the German Sport University Cologne.
文摘Objective:To examine the impact of a 6-week endurance training on red blood cell(RBC)aging and deformability of healthy participants to detect possible improved hemorheological and performance-related adaptations.Methods:A total of 31 participants(17 females and 14 males)performed a 6-week moderate training protocol(three 1-h running sessions per week at 70%of maximal heart rate).Blood was sampled before and after the training.RBCs from each participant were fractioned according to density and age into 4 RBC subfractions.Subfractions were examined for changes of RBC properties,including aging distribution,RBC deformability,RBC microparticles,and phosphatidylserine concentrations.RBC and plasma nitrite levels were measured as indicators of nitric oxide metabolism.Results:Aerobic performance,peak oxygen consumption,ventilatory thresholds,velocity at the aerobic-anaerobic threshold,and lactate at exhaustion improved after training.The relative amount of both young RBCs and old RBCs increased,and the amount of the main RBC fraction decreased.Phosphatidylserine externalization and RBC-derived microparticles decreased.Overall deformability expressed as shear stress required to achieve half-maximum deformation to theoretical maximal elongation index at infinite shear stress improved in unfractioned RBCs(p<0.001).Nitrite decreased in total(p=0.001),young(p<0.001),main(p<0.001),and old(p=0.020)aged RBCs and in plasma(p=0.002),but not in very old RBCs.Conclusion:These results indicate that non-endurance-trained healthy participants benefit from a regular moderate running training program because performance-related parameters improve and a younger RBC population with improved RBC properties is induced,which might support oxygen supply in the microcirculation.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51476095 and 51206103the Innovation Program of Shanghai Municipal Education Commission under Grant No 13YZ128the Program for Professor of Special Appointment(Eastern Scholar) at Shanghai Institutions of Higher Learning
文摘Organic-inorganic nanojunctions can result in a selective scattering of charge carrier depending on their energy, which leads to a simultaneous increase in the Seebeck coefficient S and the power factor. In this work, the nanojunction is successfully employed at the organic-inorganic semiconductor interface of polyparaphenylene （PPP） and Zn1-xAgxO nanoparticles through the sol-gel method. The presence of nanoinclusions PPP in Zno.gAgoa 0 matrix is found to be effective in improving the figure of merit （ZT） by the dual effects of an increase in the power factor consistent with the heterojunetion effect and a reduction in thermal conductivity. Zno.gAgo.10/0.1 wt% PPP exhibits a maximum figure of merit, i.e., ZT= 0.22.
文摘Sulfur content is one of the fuel properties to be monitored. Sulfur dioxide, the major product derived from organic sulfur compounds in the exhaust gas emissions, is a poison to the three-way catalysts (TWC). A gas mixture was applied to simulate the exhaust gases used in the TWC aging procedure tests. Two types of the TWC, REX-IIC and REX-IID, were tested in this study. The performance of both TWC's before and after the 100-hour sulfur aging program was compared. It was concluded that the Pt component in the TWC was apt to be poisoned by sulfur much easily than Rh. The performance of the REX-IID catalyst was generally better than that of the REX-IIC catalyst.
