Microstructure and creep properties of AZ61 alloy containing 1 and 3 wt.% Ca were investigated. The creep properties were examined using impression method under different stresses between 200 and 500 MPa at the temper...Microstructure and creep properties of AZ61 alloy containing 1 and 3 wt.% Ca were investigated. The creep properties were examined using impression method under different stresses between 200 and 500 MPa at the temperature ranging from 423 to 491 K. The microstructure of AZ61 alloy contains α(Mg) matrix and Mg17 Al12 intermetallic phases. It is shown that adding Ca to AZ61 alloy reduces the amount of Mg17 Al12 phase via forming(Mg,Al)2 Ca phase;furthermore, increasing the Ca content to 3 wt.% leads to the formation of(Mg,Al)2 Ca phase, as well as the elimination of the Mg17 Al12 phase. Creep properties of AZ61 alloy are improved with the Ca addition. The improvement in creep properties is attributed to the reduction in the amount of Mg17 Al12 phase and the formation of(Mg,Al)2 Ca phase with high thermal stability. According to the obtained creep data, it is concluded that the pipe diffusion-climb controlled dislocation creep is the dominant creep mechanism and Ca addition has no influence on this mechanism. The effect of pre-deformation on the creep properties of AZ61+3%Ca alloy reveals that the creep resistance of the alloy depends on the continuity of(Mg,Al)2 Ca phase. It is decreased by reducing the phase continuity.展开更多
The Bureau of High-Technology Research and Development (BHRD) BHRD is in charge of management for the research and; development activities in high-technology areas in CAS, including predicting the trends of high-techn...The Bureau of High-Technology Research and Development (BHRD) BHRD is in charge of management for the research and; development activities in high-technology areas in CAS, including predicting the trends of high-technology development in the light of the demands for technology which is strategic, forward-展开更多
Since the discovery that nucleases of the bacterial CRISPR(clustered regularly interspaced palindromic repeat)-associated(Cas) system can be used as easily programmable tools for genome engineering,their application m...Since the discovery that nucleases of the bacterial CRISPR(clustered regularly interspaced palindromic repeat)-associated(Cas) system can be used as easily programmable tools for genome engineering,their application massively transformed different areas of plant biology. In this review, we assess the current state of their use for crop breeding to incorporate attractive new agronomical traits into specific cultivars of various crop plants. This can be achieved by the use of Cas9/12 nucleases for double-strand break induction,resulting in mutations by non-homologous recombinatr e-tion. Strategies for performing such experiments à from Rthe design of guide RNA to the use of different transformation technologies à are evaluated. Furtherweive-more, we sum up recent developments regarding the use of nuclease-deficient Cas9/12 proteins, as DNAbinding moieties for targeting different kinds of enzyme activities to specific sites within the genome. Progress in base deamination, transcriptional induction and transcriptional repression, as well as in imaging in plants, is also discussed. As different Cas9/12 enzymes are at hand, the simultaneous application of various enzyme activities, to multiple genomic sites, is now in reach to redirect plant metabolism in a multifunctional manner and pave the way for a new level of plant synthetic biology.展开更多
The world's only captive Yangtze River dolphin, QiQi,died on July 14 at the Wuhan-based Institute of Hydrobiology (IHB) of the Chinese Academy of Sciences (CAS). At age of about 25, well advanced in years for a fr...The world's only captive Yangtze River dolphin, QiQi,died on July 14 at the Wuhan-based Institute of Hydrobiology (IHB) of the Chinese Academy of Sciences (CAS). At age of about 25, well advanced in years for a freshwater dolphin, his death is considered as a natural one.展开更多
文摘Microstructure and creep properties of AZ61 alloy containing 1 and 3 wt.% Ca were investigated. The creep properties were examined using impression method under different stresses between 200 and 500 MPa at the temperature ranging from 423 to 491 K. The microstructure of AZ61 alloy contains α(Mg) matrix and Mg17 Al12 intermetallic phases. It is shown that adding Ca to AZ61 alloy reduces the amount of Mg17 Al12 phase via forming(Mg,Al)2 Ca phase;furthermore, increasing the Ca content to 3 wt.% leads to the formation of(Mg,Al)2 Ca phase, as well as the elimination of the Mg17 Al12 phase. Creep properties of AZ61 alloy are improved with the Ca addition. The improvement in creep properties is attributed to the reduction in the amount of Mg17 Al12 phase and the formation of(Mg,Al)2 Ca phase with high thermal stability. According to the obtained creep data, it is concluded that the pipe diffusion-climb controlled dislocation creep is the dominant creep mechanism and Ca addition has no influence on this mechanism. The effect of pre-deformation on the creep properties of AZ61+3%Ca alloy reveals that the creep resistance of the alloy depends on the continuity of(Mg,Al)2 Ca phase. It is decreased by reducing the phase continuity.
文摘The Bureau of High-Technology Research and Development (BHRD) BHRD is in charge of management for the research and; development activities in high-technology areas in CAS, including predicting the trends of high-technology development in the light of the demands for technology which is strategic, forward-
基金Funding of our cooperative research by the German Federal Ministry of Education and Research (FKZ 031B0192)
文摘Since the discovery that nucleases of the bacterial CRISPR(clustered regularly interspaced palindromic repeat)-associated(Cas) system can be used as easily programmable tools for genome engineering,their application massively transformed different areas of plant biology. In this review, we assess the current state of their use for crop breeding to incorporate attractive new agronomical traits into specific cultivars of various crop plants. This can be achieved by the use of Cas9/12 nucleases for double-strand break induction,resulting in mutations by non-homologous recombinatr e-tion. Strategies for performing such experiments à from Rthe design of guide RNA to the use of different transformation technologies à are evaluated. Furtherweive-more, we sum up recent developments regarding the use of nuclease-deficient Cas9/12 proteins, as DNAbinding moieties for targeting different kinds of enzyme activities to specific sites within the genome. Progress in base deamination, transcriptional induction and transcriptional repression, as well as in imaging in plants, is also discussed. As different Cas9/12 enzymes are at hand, the simultaneous application of various enzyme activities, to multiple genomic sites, is now in reach to redirect plant metabolism in a multifunctional manner and pave the way for a new level of plant synthetic biology.
文摘The world's only captive Yangtze River dolphin, QiQi,died on July 14 at the Wuhan-based Institute of Hydrobiology (IHB) of the Chinese Academy of Sciences (CAS). At age of about 25, well advanced in years for a freshwater dolphin, his death is considered as a natural one.
