737-800 B17XX飞机起飞后上升至4500米时,右侧SOURCE和GEN OFF BUS灯亮,执行电源断开检查单,启动APU并接通电源后,右侧SORCE OFF灯灭。落地后进行GCU测试有代码IDG FAULT,该故障经过连续三个晚班排故,先后量线,更换GCU、两个IDG,故障依...737-800 B17XX飞机起飞后上升至4500米时,右侧SOURCE和GEN OFF BUS灯亮,执行电源断开检查单,启动APU并接通电源后,右侧SORCE OFF灯灭。落地后进行GCU测试有代码IDG FAULT,该故障经过连续三个晚班排故,先后量线,更换GCU、两个IDG,故障依旧。最终如何排除呢?文章在简要回顾737NG交流电源构成和IDG结构原理后,详细分析P5-4板上GEN OFF BUS灯亮问题。展开更多
Construction of a food-grade expression vector for application to lactic acid bacteria（LAB） is of importance for dairy fermentation system. An α-galactosidase（aga） gene encoding an enzyme degrading melibiose was ...Construction of a food-grade expression vector for application to lactic acid bacteria（LAB） is of importance for dairy fermentation system. An α-galactosidase（aga） gene encoding an enzyme degrading melibiose was amplified by PCR from the plasmid p RAF800 of Lactococcus lactis NZ9000. The aga gene was introduced into pMG36 e to substitute the p rimary antibiotic selectable marker of pMG36 e, resulting in construction of a new food-grade expression vector pMG36-aga. To testify the expression efficiency of exogenous gene in pMG36-aga, a 1.5 kb long α-amylase（amy） gene from Ba cillus li cheniformis was cloned by PCR and introduced into the plasmid pMG36-aga. The resultant plasimd pMG36-aga-amy was transformed into L. lactis ML23 by electroporation. The positive clones were selected with the medium containing melibiose as the sole carbon source. Th e selection efficiency of aga was 8.71×103 CFU with a standard deviation of 9.1×102 CFU ？g-1 DNA of pMG36-aga. Furthermore, the SDS-PAGE analysis showed that the pMG36-aga-amy expressed a 56.4 kDa protein which was the same as the putati ve molecular weight of α-amylase. The starch plate assay also indicated that L. lactis ML23 displayed high activity of α-amylase by expressing of amy gene of pMG36-aga-amy.展开更多
The study investigated the relationship among remittances,financial development and economic growth in a panel of 20 sub-Saharan African countries over the period of 2000 and 2015.The study used both Pooled Mean Group...The study investigated the relationship among remittances,financial development and economic growth in a panel of 20 sub-Saharan African countries over the period of 2000 and 2015.The study used both Pooled Mean Group and Mean Group/ARDL estimations with panel unit root and cointegration tests.After establishing cointegration,remittances and financial development were found to have positive effects on economic growth both in the short and the long run.The interactive term showed that financial development acted as a substitute in the remittances-growth relationship.Finally,unidirectional causal relationships were found to exist from GDP to remittances and from financial development to GDP.However,no causality existed between remittances and financial development in the SSA countries.展开更多
文摘737-800 B17XX飞机起飞后上升至4500米时,右侧SOURCE和GEN OFF BUS灯亮,执行电源断开检查单,启动APU并接通电源后,右侧SORCE OFF灯灭。落地后进行GCU测试有代码IDG FAULT,该故障经过连续三个晚班排故,先后量线,更换GCU、两个IDG,故障依旧。最终如何排除呢?文章在简要回顾737NG交流电源构成和IDG结构原理后,详细分析P5-4板上GEN OFF BUS灯亮问题。
基金supported by the National High-Tech R&D Program of China (863 Program, 2006AA10Z317)
文摘Construction of a food-grade expression vector for application to lactic acid bacteria（LAB） is of importance for dairy fermentation system. An α-galactosidase（aga） gene encoding an enzyme degrading melibiose was amplified by PCR from the plasmid p RAF800 of Lactococcus lactis NZ9000. The aga gene was introduced into pMG36 e to substitute the p rimary antibiotic selectable marker of pMG36 e, resulting in construction of a new food-grade expression vector pMG36-aga. To testify the expression efficiency of exogenous gene in pMG36-aga, a 1.5 kb long α-amylase（amy） gene from Ba cillus li cheniformis was cloned by PCR and introduced into the plasmid pMG36-aga. The resultant plasimd pMG36-aga-amy was transformed into L. lactis ML23 by electroporation. The positive clones were selected with the medium containing melibiose as the sole carbon source. Th e selection efficiency of aga was 8.71×103 CFU with a standard deviation of 9.1×102 CFU ？g-1 DNA of pMG36-aga. Furthermore, the SDS-PAGE analysis showed that the pMG36-aga-amy expressed a 56.4 kDa protein which was the same as the putati ve molecular weight of α-amylase. The starch plate assay also indicated that L. lactis ML23 displayed high activity of α-amylase by expressing of amy gene of pMG36-aga-amy.
文摘The study investigated the relationship among remittances,financial development and economic growth in a panel of 20 sub-Saharan African countries over the period of 2000 and 2015.The study used both Pooled Mean Group and Mean Group/ARDL estimations with panel unit root and cointegration tests.After establishing cointegration,remittances and financial development were found to have positive effects on economic growth both in the short and the long run.The interactive term showed that financial development acted as a substitute in the remittances-growth relationship.Finally,unidirectional causal relationships were found to exist from GDP to remittances and from financial development to GDP.However,no causality existed between remittances and financial development in the SSA countries.
