[Objective] This study aimed to screen an Na＋/H＋ antiporter gene from the halophiles colonizing in the Dagong Ancient Brine Well in Zigong City, China, and then analyze the gene structure and properties of the prote...[Objective] This study aimed to screen an Na＋/H＋ antiporter gene from the halophiles colonizing in the Dagong Ancient Brine Well in Zigong City, China, and then analyze the gene structure and properties of the protein encoded by this gene. [Method] Metagenomic DNA libraries of halophiles from the Dagong Ancient Brine Well were used for screening genes with Na＋/H＋ antiporter activity in antiporter-defi- cient E. coil KNabc strain by functional complementation. Then the start codon, stop codon, ORF, -35 region, -10 region and SD sequence of Na~/H＋ antiporter gene, as well as the molecular weight, isoelectric point, hydrophobic region, transmembrane domain, phyletic evolution and salt resistance of protein encoded by the gene were investigated. [Result] A new Na＋/H＋ antiporter gene m-nha was obtained, which ,ren- dered the antiporter-negative mutant E. coil KNabc cells with both the resistance to Na＋ and the ability to grow under alkaline conditions. [Conclusion] The structure and amino acid sequence of M-Nha was different from the previously reported Na＋/H~ antiporters, and the m-nha gene disclosed from the Dagong Ancient Brine Well was identified as a novel Na＋/H＋ antiporter gene. This study was significant not only in helping us understand the salt tolerance of halophiles in ancient brine wells and develop and utilize the genes resource, but also in exploring new salt-tolerant genes.展开更多
In order to effectively derive the inverse kinematic solution of the Delta robot and realize actuator control a description of the linear graph principle for automatically generating kinematic equations in a mechanica...In order to effectively derive the inverse kinematic solution of the Delta robot and realize actuator control a description of the linear graph principle for automatically generating kinematic equations in a mechanical system as well as the symbolic computation implementation of this procedure is reviewed and projected into the Delta robot. Based on the established linear graph representation the explicit symbolic expression of constraint equations and inverse kinematic solutions are obtained successfully using a symbolic computation engine Maple so that actuator control and trajectory tracking can be directly realized.Two practical motions the circular path and Adept motion are simulated for the validation of symbolic solutions respectively.Results indicate that the simulation satisfies the requirement of the quick motion within an acceptable threshold. Thus the precision of kinematic response can be confirmed and the correctness of inverse solution is verified.展开更多
Motion compensation is a key step for inverse synthetic aperture radar (ISAR) imaging. Many algorithms have been proposed. The rank one phase estimation (ROPE) algorithm is a good estimator for phase error widely used...Motion compensation is a key step for inverse synthetic aperture radar (ISAR) imaging. Many algorithms have been proposed. The rank one phase estimation (ROPE) algorithm is a good estimator for phase error widely used in SAR. The ROPE algorithm is used in ISAR phase compensation and the concrete implementation steps are presented. Subsequently, the performance of ROPE is analyzed. For ISAR data that fit the ROPE algorithm model, an excellent compensation effect can be obtained with high computation efficiency. Finally, ISAR real data are processed with ROPE and its imaging result is compared with that obtained by the modified Doppler centroid tracking (MDCT) method, which is a robust and good estimator in ISAR phase compensation.展开更多
基金Supported by Chunhui Plan of Ministry of Education(Z2010101)Open Fund of Food Biotechnology Key Laboratory of Sichuan Province(SZJJ2009-014)Scientific Research Foundation of Xihua University(000022)~~
文摘[Objective] This study aimed to screen an Na＋/H＋ antiporter gene from the halophiles colonizing in the Dagong Ancient Brine Well in Zigong City, China, and then analyze the gene structure and properties of the protein encoded by this gene. [Method] Metagenomic DNA libraries of halophiles from the Dagong Ancient Brine Well were used for screening genes with Na＋/H＋ antiporter activity in antiporter-defi- cient E. coil KNabc strain by functional complementation. Then the start codon, stop codon, ORF, -35 region, -10 region and SD sequence of Na~/H＋ antiporter gene, as well as the molecular weight, isoelectric point, hydrophobic region, transmembrane domain, phyletic evolution and salt resistance of protein encoded by the gene were investigated. [Result] A new Na＋/H＋ antiporter gene m-nha was obtained, which ,ren- dered the antiporter-negative mutant E. coil KNabc cells with both the resistance to Na＋ and the ability to grow under alkaline conditions. [Conclusion] The structure and amino acid sequence of M-Nha was different from the previously reported Na＋/H~ antiporters, and the m-nha gene disclosed from the Dagong Ancient Brine Well was identified as a novel Na＋/H＋ antiporter gene. This study was significant not only in helping us understand the salt tolerance of halophiles in ancient brine wells and develop and utilize the genes resource, but also in exploring new salt-tolerant genes.
基金The National Natural Science Foundation of China(No.51205208)
文摘In order to effectively derive the inverse kinematic solution of the Delta robot and realize actuator control a description of the linear graph principle for automatically generating kinematic equations in a mechanical system as well as the symbolic computation implementation of this procedure is reviewed and projected into the Delta robot. Based on the established linear graph representation the explicit symbolic expression of constraint equations and inverse kinematic solutions are obtained successfully using a symbolic computation engine Maple so that actuator control and trajectory tracking can be directly realized.Two practical motions the circular path and Adept motion are simulated for the validation of symbolic solutions respectively.Results indicate that the simulation satisfies the requirement of the quick motion within an acceptable threshold. Thus the precision of kinematic response can be confirmed and the correctness of inverse solution is verified.
文摘Motion compensation is a key step for inverse synthetic aperture radar (ISAR) imaging. Many algorithms have been proposed. The rank one phase estimation (ROPE) algorithm is a good estimator for phase error widely used in SAR. The ROPE algorithm is used in ISAR phase compensation and the concrete implementation steps are presented. Subsequently, the performance of ROPE is analyzed. For ISAR data that fit the ROPE algorithm model, an excellent compensation effect can be obtained with high computation efficiency. Finally, ISAR real data are processed with ROPE and its imaging result is compared with that obtained by the modified Doppler centroid tracking (MDCT) method, which is a robust and good estimator in ISAR phase compensation.
