We studied the relationship between insertion of the last sense codon (i.e., the codon preceding the stop codon) and the efficiency of gene expression. We inserted 64 kinds of last sense codon at the 5’ end of the st...We studied the relationship between insertion of the last sense codon (i.e., the codon preceding the stop codon) and the efficiency of gene expression. We inserted 64 kinds of last sense codon at the 5’ end of the stop codon of the green fluorescent protein (GFP) gene and introduced the modified GFP genes into Escherichia coli (E. coli). Measuring the fluorescence intensity of the GFP produced in E. coli showed that the last sense codon influenced GFP gene expression and when CCG was inserted as the last sense codon, fluorescence intensity of E. coli was increased to 2.09 fold. On the other hand, insertion of CUA caused decrease of fluorescence intensity to 0.33 fold. We hope that our findings, which may be applicable to gene engineering, will be useful for further studies of protein expression.展开更多
The dynamic characteristic evaluation is an important prerequisite for safe and reliable operation of the mediumvoltage DC integrated power system(MIPS),and the dynamic state estimation is an essential technical appro...The dynamic characteristic evaluation is an important prerequisite for safe and reliable operation of the mediumvoltage DC integrated power system(MIPS),and the dynamic state estimation is an essential technical approach to the evaluation.Unlike the electromechanical transient process in a traditional power system,periodic change in pulse load of the MIPS is an electromagnetic transient process.As the system state suddenly changes in the range of a smaller time constant,it is difficult to estimate the dynamic state due to periodic disturbance.This paper presents a dynamic mathematical model of the MIPS according to the network structure and control strategy,thereby overcoming the restrictions of algebraic variables on the estimation and developing a dynamic state estimation method based on the extended Kalman filter.Using the method of adding fictitious process noise,it is possible to solve the problem that the linearized algorithm of the MIPS model is less reliable when an abrupt change occurs in the pulse load.Therefore,the accuracy of the dynamic state estimation and the stability of the filter can be improved under the periodic disturbance of pulse load.The simulation and experimental results confirm that the proposed model and method are feasible and effective.展开更多
文摘We studied the relationship between insertion of the last sense codon (i.e., the codon preceding the stop codon) and the efficiency of gene expression. We inserted 64 kinds of last sense codon at the 5’ end of the stop codon of the green fluorescent protein (GFP) gene and introduced the modified GFP genes into Escherichia coli (E. coli). Measuring the fluorescence intensity of the GFP produced in E. coli showed that the last sense codon influenced GFP gene expression and when CCG was inserted as the last sense codon, fluorescence intensity of E. coli was increased to 2.09 fold. On the other hand, insertion of CUA caused decrease of fluorescence intensity to 0.33 fold. We hope that our findings, which may be applicable to gene engineering, will be useful for further studies of protein expression.
基金supported by the National Key Basic Research Program of China(973 Program)(No.613294)the Natural Science Foundation of China(No.51877211)
文摘The dynamic characteristic evaluation is an important prerequisite for safe and reliable operation of the mediumvoltage DC integrated power system(MIPS),and the dynamic state estimation is an essential technical approach to the evaluation.Unlike the electromechanical transient process in a traditional power system,periodic change in pulse load of the MIPS is an electromagnetic transient process.As the system state suddenly changes in the range of a smaller time constant,it is difficult to estimate the dynamic state due to periodic disturbance.This paper presents a dynamic mathematical model of the MIPS according to the network structure and control strategy,thereby overcoming the restrictions of algebraic variables on the estimation and developing a dynamic state estimation method based on the extended Kalman filter.Using the method of adding fictitious process noise,it is possible to solve the problem that the linearized algorithm of the MIPS model is less reliable when an abrupt change occurs in the pulse load.Therefore,the accuracy of the dynamic state estimation and the stability of the filter can be improved under the periodic disturbance of pulse load.The simulation and experimental results confirm that the proposed model and method are feasible and effective.
