The development of Africa is vital to the world’s sustainable development.However,African countries still face key challenges in achieving the meaningful expansion of their economies.At the High-Level Symposium on Ch...The development of Africa is vital to the world’s sustainable development.However,African countries still face key challenges in achieving the meaningful expansion of their economies.At the High-Level Symposium on China-Africa Investment Cooperation in Xiamen,southeast China’s Fujian Province,held from September 8 to 10,Chen Deming,Minister of Commerce of China,elaborates on these challenges and sees展开更多
The purpose of this study was to evaluate the viability and subsequent developmental ability of porcine germinal vesicle（GV） oocytes vitrified step-wise exposure to cryoprotectants. Oocytes were transferred to a vit...The purpose of this study was to evaluate the viability and subsequent developmental ability of porcine germinal vesicle（GV） oocytes vitrified step-wise exposure to cryoprotectants. Oocytes were transferred to a vitrification solution composed of 10% ethylene glycol（EG）,10% dimethyl sulfoxide（DMSO）, 300 g/L-1 Ficoll and 0.5 mol/L-1 sucrose（EDFS40） in a direct manner （non-preequilibrium） or in step-wise manner（ single- and two-step preequilibrium）. After vitrification and storage in liquid nitrogen, the oocytes were thawed,washed and in vitro maturation, fertilization and culture. In the non-preequilibrium group, the rates of post-thawed oocytes surviving, maturing to metaphase-Ⅱ, cleavage rate and blastocysts rate was significantly lower than that of sigle- and two-step preequilubrium groups（P<0.05）. In the single- and two- step groups, the rates of metaphase-Ⅱ stage were 46.8%, 42.7% and 49.7%, respectively, the rates which developed to blastocysts were 10.5%,11.1% and 14.8%, respectivaly. In the non-vitrified control group,the rates of oocytes maturing to metaphase-Ⅱ, developing to blastocysts was significantly higher than that vitrified groups（P<0.05）. The present study shows that the vitrification of porcine GV oocytes by a step-wise method involving two-steps preequilibrium may have advantage in maintaining the viability and subsequent production of blastocysts.展开更多
By revisiting the three stage theory for the progress of science proposed by Taketani in 1942, the footmarks of fluidization research are examined. The bubbling and fast fluidization issues were emphasized so that the...By revisiting the three stage theory for the progress of science proposed by Taketani in 1942, the footmarks of fluidization research are examined. The bubbling and fast fluidization issues were emphasized so that the future offluidization research can be discussed among scientists and engineers in a wider perspective. The first cycle of fluidization research was started in the early 1940s by an initial stage of phenomenology. The second stage of structural studies was kicked off in the early 1950s with the introduction of the two phase theory. The third stage of essential studies occurred in the early 1960s in the form of bubble hydrodynamics. The second cycle, which confirmed the aforementioned three stages closed at the turn of the century, established a general understanding of suspension structures including agglomerating fluidization, bubbling, turbulent and fast fluidizations and pneumatic transport; also established powerful measurement and numerical simulation tools.After a general remark on science, technology and society issues the interactions between fluidization technology and science are revisited. Our future directions are discussed including the tasks in the third cycle, particularly in its phenomenology stage where strong motivation and intention are always necessary, in relation also to the green reforming of the present technology. A generalized definition of ＇fluidization＇ is proposed to extend fluidization principle into much wider scientific fields, which would be effective also for wider collaborations.展开更多
文摘The development of Africa is vital to the world’s sustainable development.However,African countries still face key challenges in achieving the meaningful expansion of their economies.At the High-Level Symposium on China-Africa Investment Cooperation in Xiamen,southeast China’s Fujian Province,held from September 8 to 10,Chen Deming,Minister of Commerce of China,elaborates on these challenges and sees
基金Item supported by international coopera-tion programme of science and technology of Shanghai (No.015407005)
文摘The purpose of this study was to evaluate the viability and subsequent developmental ability of porcine germinal vesicle（GV） oocytes vitrified step-wise exposure to cryoprotectants. Oocytes were transferred to a vitrification solution composed of 10% ethylene glycol（EG）,10% dimethyl sulfoxide（DMSO）, 300 g/L-1 Ficoll and 0.5 mol/L-1 sucrose（EDFS40） in a direct manner （non-preequilibrium） or in step-wise manner（ single- and two-step preequilibrium）. After vitrification and storage in liquid nitrogen, the oocytes were thawed,washed and in vitro maturation, fertilization and culture. In the non-preequilibrium group, the rates of post-thawed oocytes surviving, maturing to metaphase-Ⅱ, cleavage rate and blastocysts rate was significantly lower than that of sigle- and two-step preequilubrium groups（P<0.05）. In the single- and two- step groups, the rates of metaphase-Ⅱ stage were 46.8%, 42.7% and 49.7%, respectively, the rates which developed to blastocysts were 10.5%,11.1% and 14.8%, respectivaly. In the non-vitrified control group,the rates of oocytes maturing to metaphase-Ⅱ, developing to blastocysts was significantly higher than that vitrified groups（P<0.05）. The present study shows that the vitrification of porcine GV oocytes by a step-wise method involving two-steps preequilibrium may have advantage in maintaining the viability and subsequent production of blastocysts.
文摘By revisiting the three stage theory for the progress of science proposed by Taketani in 1942, the footmarks of fluidization research are examined. The bubbling and fast fluidization issues were emphasized so that the future offluidization research can be discussed among scientists and engineers in a wider perspective. The first cycle of fluidization research was started in the early 1940s by an initial stage of phenomenology. The second stage of structural studies was kicked off in the early 1950s with the introduction of the two phase theory. The third stage of essential studies occurred in the early 1960s in the form of bubble hydrodynamics. The second cycle, which confirmed the aforementioned three stages closed at the turn of the century, established a general understanding of suspension structures including agglomerating fluidization, bubbling, turbulent and fast fluidizations and pneumatic transport; also established powerful measurement and numerical simulation tools.After a general remark on science, technology and society issues the interactions between fluidization technology and science are revisited. Our future directions are discussed including the tasks in the third cycle, particularly in its phenomenology stage where strong motivation and intention are always necessary, in relation also to the green reforming of the present technology. A generalized definition of ＇fluidization＇ is proposed to extend fluidization principle into much wider scientific fields, which would be effective also for wider collaborations.
