As an essential renewable mineral resource,mollusk shells can be used as handicrafts,building materials,adsor-bents,etc.However,there are few reports on the wear resistance of their structures.The Vicker’s hardness a...As an essential renewable mineral resource,mollusk shells can be used as handicrafts,building materials,adsor-bents,etc.However,there are few reports on the wear resistance of their structures.The Vicker’s hardness and friction,and wear resistance of different microstructures in mollusk shells were comparatively studied in the pre-sent work.The hardness of prismatic structures is lower than that of cross-lamellar and nacreous structures.How-ever,the experimental results of sliding tests indicate that the prismatic structure exhibits the best anti-wear ability compared with foliated,crossed-lamellar,and nacreous structures.The anti-wear and hardness do not present a positive correlation,as the wear resistance properties of different microstructures in mollusk shells are governed jointly by organic matrix,structural arrangement,and basic building block actions.The present researchfindings are expected to provide fundamental insight into the design of renewable bionic materials with high wear resistance.展开更多
Although the fracture behavior of sea urchin spines has been extensively investigated,there is as yet a lack of quantitative estimation on the effect of growth rings on the fracture properties of sea urchin spines.In ...Although the fracture behavior of sea urchin spines has been extensively investigated,there is as yet a lack of quantitative estimation on the effect of growth rings on the fracture properties of sea urchin spines.In sea urchin spines,much denser pores present in growth rings rather than porous layers.The tensile strength and fracture toughness of sea urchin spine samples with different numbers of growth rings are measured by the Boundary Effect Model(BEM).The experimental results of single-edge notched three-point bending tests indicate that the BEM is an appropriate method to estimate the fracture toughness of the present porous sea urchin spines,and the number of growth rings plays an important role in the fracture properties of spines.Specifically,the tensile strength and fracture toughness of sea urchin spines can be significantly improved with the increase in the number of growth rings,and their fracture toughness can even reach a relatively high value compared with some other porous materials with an identical porosity.The present research findings are expected to provide a fundamental insight into the design of high-performance bionic materials with a highly porous structure.展开更多
Enucleation is a crucial procedure for mammalian somatic cell nuclear transfer(SCNT), especially for domestic animal cloning. Oocytes of domestic animals such as pigs and cattle contain dark lipid droplets that hinder...Enucleation is a crucial procedure for mammalian somatic cell nuclear transfer(SCNT), especially for domestic animal cloning. Oocytes of domestic animals such as pigs and cattle contain dark lipid droplets that hinder localization and removal of the nucleus. Using an oocyte enucleation technique that can obtain a high enucleation rate but has minimal negative effects on the reprogramming potential of oocyte for cloning is bene?cial for enhancing the outcome of SCNT. In this study, we compared the pig cloning ef?ciency resulting from blind aspiration-based(BA-B) enucleation and spindle imaging system-assisted(SIS-A) enucleation, and compared the pig SCNT success rate associated with BA-B enucleation and blind aspiration plus post-enucleation staining-based(BAPPS-B) enucleation. SIS-A enucleation achieved a signi?cantly higher oocyte enucleation success rate and tended to obtain a higher in vivo full term development rate of SCNT embryos than BA-B enucleation. BAPPS-B enucleation also obtained signi?cantly higher in vitro as well as in vivo full term development ef?ciency of cloned porcine embryos than BA-B enucleation. These data indicate that SIS-A and BAPPS-B enucleation are better approaches for pig SCNT than BA-B enucleation.展开更多
基金This work was supported by the National Natural Science Foundation of China(Grant No.51902043)the Fundamental Research Funds for the Central Universities(Grant Nos.N2102007,N2102002,and N2202011)This work was also partially supported by the National Natural Science Foundation of China(Grant Nos.51871048 and 52171108).
文摘As an essential renewable mineral resource,mollusk shells can be used as handicrafts,building materials,adsor-bents,etc.However,there are few reports on the wear resistance of their structures.The Vicker’s hardness and friction,and wear resistance of different microstructures in mollusk shells were comparatively studied in the pre-sent work.The hardness of prismatic structures is lower than that of cross-lamellar and nacreous structures.How-ever,the experimental results of sliding tests indicate that the prismatic structure exhibits the best anti-wear ability compared with foliated,crossed-lamellar,and nacreous structures.The anti-wear and hardness do not present a positive correlation,as the wear resistance properties of different microstructures in mollusk shells are governed jointly by organic matrix,structural arrangement,and basic building block actions.The present researchfindings are expected to provide fundamental insight into the design of renewable bionic materials with high wear resistance.
基金This work was supported by the National Natural Science Foundation of China[Grant No.51902043]the Fundamental Research Funds for the Central Universities[Grant No.N2102007,and N2102002]。
文摘Although the fracture behavior of sea urchin spines has been extensively investigated,there is as yet a lack of quantitative estimation on the effect of growth rings on the fracture properties of sea urchin spines.In sea urchin spines,much denser pores present in growth rings rather than porous layers.The tensile strength and fracture toughness of sea urchin spine samples with different numbers of growth rings are measured by the Boundary Effect Model(BEM).The experimental results of single-edge notched three-point bending tests indicate that the BEM is an appropriate method to estimate the fracture toughness of the present porous sea urchin spines,and the number of growth rings plays an important role in the fracture properties of spines.Specifically,the tensile strength and fracture toughness of sea urchin spines can be significantly improved with the increase in the number of growth rings,and their fracture toughness can even reach a relatively high value compared with some other porous materials with an identical porosity.The present research findings are expected to provide a fundamental insight into the design of high-performance bionic materials with a highly porous structure.
基金supported by the National Natural Science Foundation of China (31772554)the Department of Science and Technology of Guangdong Province, China (2016B020233006, 2015TX01N081 and 2016A020210074)the team project of Guangdong Agricultural Department (2017LM2148)
文摘Enucleation is a crucial procedure for mammalian somatic cell nuclear transfer(SCNT), especially for domestic animal cloning. Oocytes of domestic animals such as pigs and cattle contain dark lipid droplets that hinder localization and removal of the nucleus. Using an oocyte enucleation technique that can obtain a high enucleation rate but has minimal negative effects on the reprogramming potential of oocyte for cloning is bene?cial for enhancing the outcome of SCNT. In this study, we compared the pig cloning ef?ciency resulting from blind aspiration-based(BA-B) enucleation and spindle imaging system-assisted(SIS-A) enucleation, and compared the pig SCNT success rate associated with BA-B enucleation and blind aspiration plus post-enucleation staining-based(BAPPS-B) enucleation. SIS-A enucleation achieved a signi?cantly higher oocyte enucleation success rate and tended to obtain a higher in vivo full term development rate of SCNT embryos than BA-B enucleation. BAPPS-B enucleation also obtained signi?cantly higher in vitro as well as in vivo full term development ef?ciency of cloned porcine embryos than BA-B enucleation. These data indicate that SIS-A and BAPPS-B enucleation are better approaches for pig SCNT than BA-B enucleation.