Arsenic is a ubiquitous environmental pollutant.Microbe-mediated arsenic biotransformations significantly infuence arsenic mobility and toxicity.Arsenic transformations by soil and aquatic organisms have been well doc...Arsenic is a ubiquitous environmental pollutant.Microbe-mediated arsenic biotransformations significantly infuence arsenic mobility and toxicity.Arsenic transformations by soil and aquatic organisms have been well documented,while little is known regarding effects due to endophytic bacteria.An endophyte Pseudomonas putida ARS1 was isolated from rice grown in arsenic contaminated soil.P.putida ARS1 shows high tolerance to arsenite(As(Ⅲ))and arsenate(As(V)),and exhibits efficient As(V)reduction and As(Ⅲ)effux activities.When exposed to 0.6 mg/L As(V),As(V)in the medium was completely converted to As(Ⅲ)by P.putida ARS1 within 4 hr.Genome sequencing showed that P.putida ARS1 has two chromosomal arsenic resistance gene clusters(arsRCBH)that contribute to efficient As(V)reduction and As(Ⅲ)effux,and result in high resistance to arsenicals.Wolffia globosa is a strong arsenic accumulator with high potential for arsenic phytoremediation,which takes up As(Ⅲ)more efficiently than As(V).Co-culture of P.putida ARS1 and W.globosa enhanced arsenic accumulation in W.globosa by 69%,and resulted in 91%removal of arsenic(at initial concentration of 0.6 mg/L As(V))from water within 3 days.This study provides a promising strategy for in situ arsenic phytoremediation through the cooperation of plant and endophytic bacterium.展开更多
In this paper,we consider an inverse time-dependent source problem of heat conduction equation.Firstly,the ill-posedness and conditional stability of this inverse source problem is analyzed.Then,a finite difference in...In this paper,we consider an inverse time-dependent source problem of heat conduction equation.Firstly,the ill-posedness and conditional stability of this inverse source problem is analyzed.Then,a finite difference inversion method is proposed for reconstructing the time-dependent source from a nonlocal measurement.The existence and uniqueness of the finite difference inverse solutions are rigorously analyzed,and the convergence is proved.Combined with the mollification method,the proposed finite difference inversion method can obtain more stable reconstructions from the nonlocal data with noise.Finally,numerical examples are given to illustrate the efficiency and convergence of the proposed finite difference inversion method.展开更多
This paper presents an adaptive equivalent-input-disturbance(AEID)approach that contains a new adjustable gain to improve disturbance-rejection performance.A linear matrix inequality is derived to design the parameter...This paper presents an adaptive equivalent-input-disturbance(AEID)approach that contains a new adjustable gain to improve disturbance-rejection performance.A linear matrix inequality is derived to design the parameters of a control system.An adaptive law for the adjustable gain is presented based on the combination of the root locus method and Lyapunov stability theory to guarantee the stability of the AEID-based system.The adjustable gain is limited in an allowable range and the information for adjusting is obtained from the state of the system.Simulation results show that the method is effective and robust.A comparison with the conventional EID approach demonstrates the validity and superiority of the method.展开更多
基金supported by the National Natural Science Foundation of China (Nos.41991332,41977323 and 42090063)the National Institutes of Health (No.R35 GM136211)。
文摘Arsenic is a ubiquitous environmental pollutant.Microbe-mediated arsenic biotransformations significantly infuence arsenic mobility and toxicity.Arsenic transformations by soil and aquatic organisms have been well documented,while little is known regarding effects due to endophytic bacteria.An endophyte Pseudomonas putida ARS1 was isolated from rice grown in arsenic contaminated soil.P.putida ARS1 shows high tolerance to arsenite(As(Ⅲ))and arsenate(As(V)),and exhibits efficient As(V)reduction and As(Ⅲ)effux activities.When exposed to 0.6 mg/L As(V),As(V)in the medium was completely converted to As(Ⅲ)by P.putida ARS1 within 4 hr.Genome sequencing showed that P.putida ARS1 has two chromosomal arsenic resistance gene clusters(arsRCBH)that contribute to efficient As(V)reduction and As(Ⅲ)effux,and result in high resistance to arsenicals.Wolffia globosa is a strong arsenic accumulator with high potential for arsenic phytoremediation,which takes up As(Ⅲ)more efficiently than As(V).Co-culture of P.putida ARS1 and W.globosa enhanced arsenic accumulation in W.globosa by 69%,and resulted in 91%removal of arsenic(at initial concentration of 0.6 mg/L As(V))from water within 3 days.This study provides a promising strategy for in situ arsenic phytoremediation through the cooperation of plant and endophytic bacterium.
基金supported by National Natural Science Foundation of China(11561003,11661004,11761007)Natural Science Foundation of Jiangxi Province(20161BAB201034)Foundation of Academic and Technical Leaders Program for Major Subjects in Jiangxi Province(20172BCB22019)。
文摘In this paper,we consider an inverse time-dependent source problem of heat conduction equation.Firstly,the ill-posedness and conditional stability of this inverse source problem is analyzed.Then,a finite difference inversion method is proposed for reconstructing the time-dependent source from a nonlocal measurement.The existence and uniqueness of the finite difference inverse solutions are rigorously analyzed,and the convergence is proved.Combined with the mollification method,the proposed finite difference inversion method can obtain more stable reconstructions from the nonlocal data with noise.Finally,numerical examples are given to illustrate the efficiency and convergence of the proposed finite difference inversion method.
基金This work was supported by National Natural Science Foundation of China(No.61873348)National Key R&D Program of China(No.2017YFB1300900)+1 种基金Hubei Provincial Natural Science Foundation of China(No.2015CFA010)the 111 Project,China(No.B17040).
文摘This paper presents an adaptive equivalent-input-disturbance(AEID)approach that contains a new adjustable gain to improve disturbance-rejection performance.A linear matrix inequality is derived to design the parameters of a control system.An adaptive law for the adjustable gain is presented based on the combination of the root locus method and Lyapunov stability theory to guarantee the stability of the AEID-based system.The adjustable gain is limited in an allowable range and the information for adjusting is obtained from the state of the system.Simulation results show that the method is effective and robust.A comparison with the conventional EID approach demonstrates the validity and superiority of the method.
