Triangular-plate added damping and stiffness(TADAS)devices are reliable metallic energy dissipaters for seismic upgrading used in design and retrofitting of civil structures.Conventional TADAS devices are designed wit...Triangular-plate added damping and stiffness(TADAS)devices are reliable metallic energy dissipaters for seismic upgrading used in design and retrofitting of civil structures.Conventional TADAS devices are designed with closedended slots.In this study,a modified form of the TADAS device is proposed with open-ended slots in order to reduce the manufacture cost,facilitate the assembling and avoid abrupt stiffness increase.Cyclic and monotonic loading tests are then conducted to investigate the mechanical characteristics of the modified TADAS devices with regular Q345 steel and lowyield point LY160 steel triangular plates.The test results show that although the hysteresis performances are stable,the cyclic hardening behavior is different between the TADAS specimens with different grades of steel.The TADAS specimen with LY160 triangular plates exhibits more significant overstrength behavior than the one with Q345 triangular plates in cyclic loading,which is unsuitable to be described by the classic Bouc-Wen model.Therefore,a modified Bouc-Wen model is proposed to describe such overstrength behavior.It is shown that the modified model is able to simulate different extent of overstrength behavior in cyclic loading,based on which the cyclic hardening behavior of the TADAS specimen with LY160 triangular plates can be well described.展开更多
TADAS dampers are a type of passive structural control system used in the seismic design or retrofitting of structures.These types of dampers are designed so that they would yield before the main components of the str...TADAS dampers are a type of passive structural control system used in the seismic design or retrofitting of structures.These types of dampers are designed so that they would yield before the main components of the structure during earthquake.This dissipates a large portion of the earthquake’s energy and reduces the energy dissipation demand in the main components of the structure.Considering its suitable performance,this damper has been the subject of numerous studies.However,there are still ambiguities regarding the effect of the number of these dampers on the retrofitting of reinforced concrete(RC)frames and their design procedure.In this study,a singlestory,single-bay RC frame with the scale of 1:3,equipped with the TADAS damper,was subjected to hysteresis loading until the drift of 4%.Then,for further assessment,48 calibrated numerical models were constructed in ABAQUS and the effects of the number of TADAS dampers and column axial force upon the stiffness,strength,and ductility of the frame were accurately investigated.Also,a number of formulations were presented to calculate how the stiffness and lateral strength of the retrofitted frame are affected by an increase in the number of the TADAS plates.The results showed that if the shear capacity of the retrofitted frame is three times that of the initial frame,the structure would have the best response.In addition,if the axial force in the columns exceeds 0.2 Pcr the energy dissipation and ductility factor of the frame drastically decrease.展开更多
CRISPR-mediated base editors have been widely used to correct defective alleles and create novel alleles by artificial evolution for the rapid genetic improvement of crops.The editing capabilities of base editors stri...CRISPR-mediated base editors have been widely used to correct defective alleles and create novel alleles by artificial evolution for the rapid genetic improvement of crops.The editing capabilities of base editors strictly rely on the performance of various nucleotide modification enzymes.Compared with the welldeveloped adenine base editors(ABEs),cytosine base editors(CBEs)and dual base editors suffer from unstable editing efficiency and patterns at different genomic loci in rice,significantly limiting their application.Here,we comprehensively examined the base editing activities of multiple evolved TadA8e variants in rice.We found that both TadA-CDd and TadA-E27R/N46L achieved more robust C-to-T editing than previously reported hyperactive hAID*D,and TadA-CDd outperformed TadA-E27R/N46L.A C-to-G base editor(CGBE)engineered with TadA-CDd and OsUNG performed highly efficient C-to-G editing in rice compared with that of TadA-N46P.In addition,a dual base editor constructed with a single protein,TadDE,enabled simultaneous,highly efficient C-to-T and A-to-G editing in rice.Collectively,our results demonstrate that TadA8e derivatives improve both CBEs and dual base editors in rice,providing a powerful way to induce diverse nucleotide substitutions for plant genome editing.展开更多
Recently reported adenine base editors(ABEs)exhibit powerful potential for targeted gene correction as well as developing gain-of-function mutants and novel germplasms for both gene function studies and crop breeding....Recently reported adenine base editors(ABEs)exhibit powerful potential for targeted gene correction as well as developing gain-of-function mutants and novel germplasms for both gene function studies and crop breeding.However,editing efficiency varies significantly among different target sites.Here,we investigated the activities of three evolved E.coli adenosine deaminase TadA variants(TadA8e,TadA8.17,and TadA8.20)side-by-side in transgenic rice.We found that TadA8e outperforms TadA8.17 and TadA8.20,and induces efficient A-to-G conversion at all tested sites in the rice genome,including those that were un-editable by ABE7.10 in our previous experiments.Furthermore,V82S/Q154R mutations were incorporated into TadA8e,resulting in a new variant that we named TadA9.Our data show that TadA9 is broadly compatible with CRISPR/SpCas9,CRISPR/SpCas9-NG,and CRISPR/SpRY,as well as CRISPR/ScCas9 nickase systems,achieving comparable or enhanced editing in a larger editing window at diverse PAM sites as compared with TadA8e.Finally,TadA9 was used to simultaneously install novel SNPs in four endogenous herbicide target genes in the commercial rice cultivar Nangeng 46 for potential field application in.weed control.Collectively,we successfully generated a series of novel ABEs that can efficiently edit adenosines in the rice genome.Our findings suggest that TadA9 and TadA8e have great potentials in the development of plant base editors and crop molecular breeding.展开更多
Dear Editor The newly developed CRISPR/Cas9-mediated base editing technology with cytosine deaminase is capable of precisely and efficiently introducing point mutations at the target genomic locus, which does not requ...Dear Editor The newly developed CRISPR/Cas9-mediated base editing technology with cytosine deaminase is capable of precisely and efficiently introducing point mutations at the target genomic locus, which does not require double-stranded DNA breaks or any donor templates and thus exhibit a great potential for gene correction and genetic diversification in yeasts, plants, and mammalian and human cells （Komor et al., 2016; Nishida et al., 2016; Lu and Zhu, 2017; Ren et al., 2017）.展开更多
基金National Key Technology R&D Program of China during the 12th Five-Year Plan Period under Grant No.2012BAJ13B01。
文摘Triangular-plate added damping and stiffness(TADAS)devices are reliable metallic energy dissipaters for seismic upgrading used in design and retrofitting of civil structures.Conventional TADAS devices are designed with closedended slots.In this study,a modified form of the TADAS device is proposed with open-ended slots in order to reduce the manufacture cost,facilitate the assembling and avoid abrupt stiffness increase.Cyclic and monotonic loading tests are then conducted to investigate the mechanical characteristics of the modified TADAS devices with regular Q345 steel and lowyield point LY160 steel triangular plates.The test results show that although the hysteresis performances are stable,the cyclic hardening behavior is different between the TADAS specimens with different grades of steel.The TADAS specimen with LY160 triangular plates exhibits more significant overstrength behavior than the one with Q345 triangular plates in cyclic loading,which is unsuitable to be described by the classic Bouc-Wen model.Therefore,a modified Bouc-Wen model is proposed to describe such overstrength behavior.It is shown that the modified model is able to simulate different extent of overstrength behavior in cyclic loading,based on which the cyclic hardening behavior of the TADAS specimen with LY160 triangular plates can be well described.
文摘TADAS dampers are a type of passive structural control system used in the seismic design or retrofitting of structures.These types of dampers are designed so that they would yield before the main components of the structure during earthquake.This dissipates a large portion of the earthquake’s energy and reduces the energy dissipation demand in the main components of the structure.Considering its suitable performance,this damper has been the subject of numerous studies.However,there are still ambiguities regarding the effect of the number of these dampers on the retrofitting of reinforced concrete(RC)frames and their design procedure.In this study,a singlestory,single-bay RC frame with the scale of 1:3,equipped with the TADAS damper,was subjected to hysteresis loading until the drift of 4%.Then,for further assessment,48 calibrated numerical models were constructed in ABAQUS and the effects of the number of TADAS dampers and column axial force upon the stiffness,strength,and ductility of the frame were accurately investigated.Also,a number of formulations were presented to calculate how the stiffness and lateral strength of the retrofitted frame are affected by an increase in the number of the TADAS plates.The results showed that if the shear capacity of the retrofitted frame is three times that of the initial frame,the structure would have the best response.In addition,if the axial force in the columns exceeds 0.2 Pcr the energy dissipation and ductility factor of the frame drastically decrease.
基金supported by the STI 2030-Major Projects(2023ZD04074)the National Key Research and Development Program of China(2023YFD1202900)+2 种基金the Nanfan special project of the Chinese Academy of Agricultural Sciences(YBXM2313)the Hainan Seed Industry Laboratory(project of B23CJ0208)the Agricultural Science and Technology Innovation Program of the Chinese Academy of Agricultural Sciences.
文摘CRISPR-mediated base editors have been widely used to correct defective alleles and create novel alleles by artificial evolution for the rapid genetic improvement of crops.The editing capabilities of base editors strictly rely on the performance of various nucleotide modification enzymes.Compared with the welldeveloped adenine base editors(ABEs),cytosine base editors(CBEs)and dual base editors suffer from unstable editing efficiency and patterns at different genomic loci in rice,significantly limiting their application.Here,we comprehensively examined the base editing activities of multiple evolved TadA8e variants in rice.We found that both TadA-CDd and TadA-E27R/N46L achieved more robust C-to-T editing than previously reported hyperactive hAID*D,and TadA-CDd outperformed TadA-E27R/N46L.A C-to-G base editor(CGBE)engineered with TadA-CDd and OsUNG performed highly efficient C-to-G editing in rice compared with that of TadA-N46P.In addition,a dual base editor constructed with a single protein,TadDE,enabled simultaneous,highly efficient C-to-T and A-to-G editing in rice.Collectively,our results demonstrate that TadA8e derivatives improve both CBEs and dual base editors in rice,providing a powerful way to induce diverse nucleotide substitutions for plant genome editing.
基金supported by grants from the National Transgenic Science and Technology Program of China(2019ZX08010-003)to F.Y.the National Natural Science Foundation of China(31871948)the Fundamental Research Funds,and the Agricultural Science and Technology Innovation Program of the Chinese Academy of Agricultural Sciences(Y2020PT26)to H.Z.
文摘Recently reported adenine base editors(ABEs)exhibit powerful potential for targeted gene correction as well as developing gain-of-function mutants and novel germplasms for both gene function studies and crop breeding.However,editing efficiency varies significantly among different target sites.Here,we investigated the activities of three evolved E.coli adenosine deaminase TadA variants(TadA8e,TadA8.17,and TadA8.20)side-by-side in transgenic rice.We found that TadA8e outperforms TadA8.17 and TadA8.20,and induces efficient A-to-G conversion at all tested sites in the rice genome,including those that were un-editable by ABE7.10 in our previous experiments.Furthermore,V82S/Q154R mutations were incorporated into TadA8e,resulting in a new variant that we named TadA9.Our data show that TadA9 is broadly compatible with CRISPR/SpCas9,CRISPR/SpCas9-NG,and CRISPR/SpRY,as well as CRISPR/ScCas9 nickase systems,achieving comparable or enhanced editing in a larger editing window at diverse PAM sites as compared with TadA8e.Finally,TadA9 was used to simultaneously install novel SNPs in four endogenous herbicide target genes in the commercial rice cultivar Nangeng 46 for potential field application in.weed control.Collectively,we successfully generated a series of novel ABEs that can efficiently edit adenosines in the rice genome.Our findings suggest that TadA9 and TadA8e have great potentials in the development of plant base editors and crop molecular breeding.
基金This study was supported by grants from the National Key Research and Development Program of China （2017YFD0200900） and the Agricultural Science and Technology Innovation Program of The Chinese Academy of Agricultural Sciences to H.Z., and a grant from the National Natural Science Foundation of China （31701780） to F.Y.
文摘Dear Editor The newly developed CRISPR/Cas9-mediated base editing technology with cytosine deaminase is capable of precisely and efficiently introducing point mutations at the target genomic locus, which does not require double-stranded DNA breaks or any donor templates and thus exhibit a great potential for gene correction and genetic diversification in yeasts, plants, and mammalian and human cells （Komor et al., 2016; Nishida et al., 2016; Lu and Zhu, 2017; Ren et al., 2017）.
