The effect of Er on the microhardness and precipitation behavior of the heat-treated Al−Si−Mg alloy was investigated by microhardness tester and TEM.As a comparison,the influence of natural aging was also studied.It i...The effect of Er on the microhardness and precipitation behavior of the heat-treated Al−Si−Mg alloy was investigated by microhardness tester and TEM.As a comparison,the influence of natural aging was also studied.It is shown that the thermal stability of the over-aged Al−Si−Mg−Er alloy is highly related to the average size of the precipitates.The average size ofβ''precipitates in Al−Si−Mg−Er alloy is smaller than that in Al−Si−Mg alloy,and the distribution is more localized under condition of without introducing natural aging.However,when natural aging is introduced before artificial aging,the Al−Si−Mg−Er alloy has similar average size and distribution of precipitates with the Al−Si−Mg alloy,resulting in similar mechanical properties.The effect of Er on the precipitation kinetics in the alloy was also discussed in detail to explain these phenomena.展开更多
Many previous studies have focused on the foraging behaviors and strategies of the red imported fire ants, Solenopsis invicta Buren on solid food or granular bait; little attention has been paid to how liquid sugar is...Many previous studies have focused on the foraging behaviors and strategies of the red imported fire ants, Solenopsis invicta Buren on solid food or granular bait; little attention has been paid to how liquid sugar is fed upon. In the present study, behavioral responses ofS. invicta to 25% sucrose water droplets were observed. Five foraging patterns were identified in S. invicta colonies under laboratory conditions： （i） no feeding, no sucrose water feeding was observed; （ii） surround feeding, ants surrounded and fed along the edge of the sucrose droplet; （iii） stacked feeding, ants stacked and fed along the edge of the sucrose droplet; （iv） droplet-break feeding, ants broke the liquid droplet and sucked sucrose water that spread on surface of the substance or soil particles previously transported by ants; and （v） cover feeding, whole surface of the sucrose droplet was covered by layers of feeding ants. This is the first time cover feeding in S. invicta has been reported, which obviously requires more ants compared to the other patterns. In addition, individual ants were tracked in videos under laboratory conditions, and behavioral repertoires that led to stacking, covering and droplet-breaking were identified and described. The field investigation showed that surround feeding was most frequently performed by S. invicta foragers; however, cover feeding was not observed under field conditions during this study. Both laboratory and field studies showed colony-level variations in sugar-water feeding.展开更多
Eusocial insects have evolved diverse particle-use behaviors.A previous study reported that red imported fire ants,Solenopsis invicta Buren,deposited soil particles on substances treated with essential balm,a fire ant...Eusocial insects have evolved diverse particle-use behaviors.A previous study reported that red imported fire ants,Solenopsis invicta Buren,deposited soil particles on substances treated with essential balm,a fire ant repellent.We hypothesized that S.invicta modifies inaccessible surfaces by covering them with soil particles to facilitate food search and transportation.Here,laboratory experiments were conducted to study the particle-covering behavior of.S.invicta in response to viscose surfaces or surfaces treated with essential balm or liquid paraffin in the presence of real food(sausage)or non-food objects(acrylic plates).S.invicta workers deposited significantly more soil particles on these three types of treated surfaces than on untreated surfaces.In addition,significantly more particles were relocated on viscose and parafTin-smeared surfaces in the presence of food than in the presence of non-food objects.The particle-covering behavior on viscose surfaces was also observed in the field.Interestingly,when no soil particles were available,ants searched and transported food on viscose surfaces only if the surfaces were artificially covered with sufficient quantities of soil particles but could not do so on viscose surfaces without soil particles or with insutTicient quantities of soil particles.In addition,ants actively relocated particles to cover viscose surfaces if the transportation distance was within 200 mm,whereas significantly fewer particles were relocated at longer transportation distances(400 mm).Our study provides a novel example of particle use by fire ants during foraging.展开更多
动脉粥样硬化(atherosclerosis,As)斑块是导致血管栓塞,诱发急性心脑血管事件发生的病理基础,逆转、消退斑块是治疗As的理想目标。目前临床主要通过降脂、抗血小板药物以及戒烟、酒等措施,延缓斑块进展,稳定斑块,尚无能够逆转As斑块的...动脉粥样硬化(atherosclerosis,As)斑块是导致血管栓塞,诱发急性心脑血管事件发生的病理基础,逆转、消退斑块是治疗As的理想目标。目前临床主要通过降脂、抗血小板药物以及戒烟、酒等措施,延缓斑块进展,稳定斑块,尚无能够逆转As斑块的治疗方案。N Eng J Med曾报道1例42岁女性患者,在接受充分的生活干预及药物治疗3年后.展开更多
The growth behavior of Al_3Ni intermetallic compounds（IMCs）during the directional solidification of Al-10 wt%Ni alloy was investigated by synchrotron radiography.Two main growth patterns of primary Al_3Ni phase,I-li...The growth behavior of Al_3Ni intermetallic compounds（IMCs）during the directional solidification of Al-10 wt%Ni alloy was investigated by synchrotron radiography.Two main growth patterns of primary Al_3Ni phase,I-like and V-like,appeared during solidification,and I-like Al_3Ni phase grew faster than V-like phase,which can be explained by the minimum energy criterion.The growth of I-like phase can be divided into two stages and was mainly affected by undercooling and Ni concentration.We also found that V-like Al_3Ni phase can evolve into M-like phase during solidification.展开更多
基金The authors are grateful for the financial supports from the National Key Research and Development Program of China(2016YFB0300801)the National Natural Science Foundation of China(11904093,51831004,51671082,51471067 and 11427806).
文摘The effect of Er on the microhardness and precipitation behavior of the heat-treated Al−Si−Mg alloy was investigated by microhardness tester and TEM.As a comparison,the influence of natural aging was also studied.It is shown that the thermal stability of the over-aged Al−Si−Mg−Er alloy is highly related to the average size of the precipitates.The average size ofβ''precipitates in Al−Si−Mg−Er alloy is smaller than that in Al−Si−Mg alloy,and the distribution is more localized under condition of without introducing natural aging.However,when natural aging is introduced before artificial aging,the Al−Si−Mg−Er alloy has similar average size and distribution of precipitates with the Al−Si−Mg alloy,resulting in similar mechanical properties.The effect of Er on the precipitation kinetics in the alloy was also discussed in detail to explain these phenomena.
基金This work was funded by the National Natural Science Foundation of China （Grant No. 31500530）, and the Young Investigator Research Grant to Cai Wang （provided by the College of Forestry and Landscape Architecture, South China Agricultural University）.
文摘Many previous studies have focused on the foraging behaviors and strategies of the red imported fire ants, Solenopsis invicta Buren on solid food or granular bait; little attention has been paid to how liquid sugar is fed upon. In the present study, behavioral responses ofS. invicta to 25% sucrose water droplets were observed. Five foraging patterns were identified in S. invicta colonies under laboratory conditions： （i） no feeding, no sucrose water feeding was observed; （ii） surround feeding, ants surrounded and fed along the edge of the sucrose droplet; （iii） stacked feeding, ants stacked and fed along the edge of the sucrose droplet; （iv） droplet-break feeding, ants broke the liquid droplet and sucked sucrose water that spread on surface of the substance or soil particles previously transported by ants; and （v） cover feeding, whole surface of the sucrose droplet was covered by layers of feeding ants. This is the first time cover feeding in S. invicta has been reported, which obviously requires more ants compared to the other patterns. In addition, individual ants were tracked in videos under laboratory conditions, and behavioral repertoires that led to stacking, covering and droplet-breaking were identified and described. The field investigation showed that surround feeding was most frequently performed by S. invicta foragers; however, cover feeding was not observed under field conditions during this study. Both laboratory and field studies showed colony-level variations in sugar-water feeding.
基金supported by the Pearl River S&T Nova Program of Guangzhou(201806010182).
文摘Eusocial insects have evolved diverse particle-use behaviors.A previous study reported that red imported fire ants,Solenopsis invicta Buren,deposited soil particles on substances treated with essential balm,a fire ant repellent.We hypothesized that S.invicta modifies inaccessible surfaces by covering them with soil particles to facilitate food search and transportation.Here,laboratory experiments were conducted to study the particle-covering behavior of.S.invicta in response to viscose surfaces or surfaces treated with essential balm or liquid paraffin in the presence of real food(sausage)or non-food objects(acrylic plates).S.invicta workers deposited significantly more soil particles on these three types of treated surfaces than on untreated surfaces.In addition,significantly more particles were relocated on viscose and parafTin-smeared surfaces in the presence of food than in the presence of non-food objects.The particle-covering behavior on viscose surfaces was also observed in the field.Interestingly,when no soil particles were available,ants searched and transported food on viscose surfaces only if the surfaces were artificially covered with sufficient quantities of soil particles but could not do so on viscose surfaces without soil particles or with insutTicient quantities of soil particles.In addition,ants actively relocated particles to cover viscose surfaces if the transportation distance was within 200 mm,whereas significantly fewer particles were relocated at longer transportation distances(400 mm).Our study provides a novel example of particle use by fire ants during foraging.
文摘动脉粥样硬化(atherosclerosis,As)斑块是导致血管栓塞,诱发急性心脑血管事件发生的病理基础,逆转、消退斑块是治疗As的理想目标。目前临床主要通过降脂、抗血小板药物以及戒烟、酒等措施,延缓斑块进展,稳定斑块,尚无能够逆转As斑块的治疗方案。N Eng J Med曾报道1例42岁女性患者,在接受充分的生活干预及药物治疗3年后.
基金supported by the National Natural Science Foundation of China (No. 51374144)Shanghai Municipal Natural Science Foundation (No. 13ZR1420600)Shanghai RisingStar Program (No. 14QA1402300)
文摘The growth behavior of Al_3Ni intermetallic compounds（IMCs）during the directional solidification of Al-10 wt%Ni alloy was investigated by synchrotron radiography.Two main growth patterns of primary Al_3Ni phase,I-like and V-like,appeared during solidification,and I-like Al_3Ni phase grew faster than V-like phase,which can be explained by the minimum energy criterion.The growth of I-like phase can be divided into two stages and was mainly affected by undercooling and Ni concentration.We also found that V-like Al_3Ni phase can evolve into M-like phase during solidification.
