A new multi-band and high-speed endoscope diagnostic for the observation of visible light has been successfully developed on the Experimental Advanced Superconducting Tokamak.The mirror with an aperture is designed at...A new multi-band and high-speed endoscope diagnostic for the observation of visible light has been successfully developed on the Experimental Advanced Superconducting Tokamak.The mirror with an aperture is designed at the head of the optical system.Based on two dichroic mirrors,the system is divided into three imaging mirror groups with different bands,i.e.B(380-500 nm),G(500-580 nm)and R(580-750 nm)bands,and its focal length is 16 mm with a relatively large aperture of D/f=1:4.The spatial resolution is less than 5 mm near the object distance of 1750 mm with the camera NAC ACS-1 M60.This optical system will be used to contrastively study both the spatial distribution and time evolution of different impurities in the same field of view.The experimental results confirm that it can be applied to the recognition of plasma boundary and related physical research.展开更多
The specific functions of the genes encoding arginine biosynthesis enzymes in plants are not well characterized. We report the isolation and characterization of Arabidopsis thaliana N-acetylglutamate kinase （NAGK）, ...The specific functions of the genes encoding arginine biosynthesis enzymes in plants are not well characterized. We report the isolation and characterization of Arabidopsis thaliana N-acetylglutamate kinase （NAGK）, which catalyzes the second step of arginine biosynthesis. NAGK is a plastid-localized protein and is expressed during most developmental processes in Arabidopsis. Heterologous expression of the Arabidopsis NAGK gene in a NAGK-deficient Escherichia coli strain fully restores bacterial growth on arginine-deficient medium, nagk mutant pollen tubes grow more slowly than wild type pollen tubes and the phenotype is restored by either specifically through complementation by NAGK in pollen, or exogenous supplementation of arginine, nagk female gametophytes are defective in micropylar pollen tube guidance due to the fact that female gametophyte cell fate specification was specifically affected. Expression of NAGK in synergid cells rescues the defect of nagk female gametophytes. Loss- of-function of NAGK results in Arabidopsis embryos not developing beyond the four-celled embryo stage. The embryo-defective phenotype in nagk/NAGK plants cannot be rescued by watering nagk/NAGK plants with arginine or ornithine supplementation. In conclusion, our results reveal a novel role of NAGK and arginine in regulating gametophyte function and embryo development, and provide valuable insights into arginine transport during embryo development.展开更多
A mild and efficient enantioselective one-pot synthesis of β-sulfonyl ketones and trisubstituted tetrahydrothiophenes via introducing 1,4-dithiane-2,5-diol to the simple kinetic resolution of β-sulfonyl ketones has ...A mild and efficient enantioselective one-pot synthesis of β-sulfonyl ketones and trisubstituted tetrahydrothiophenes via introducing 1,4-dithiane-2,5-diol to the simple kinetic resolution of β-sulfonyl ketones has been described herein. The one-pot reaction sequence including kinetic resolution and cascade sulfa-Michael/Aldol reaction proceeded successively to afford corresponding sulfonyl ketones and tetrahydrothiophenes with high enantioselectivities（85%-98% ee and 84%-95% ee）.展开更多
Summary During embryogenesis, plants are thought to use a mechanism that allows the suspensor to maintain its identity. Here, we reported that RPL18a is involved in this mechanism in Arabidopsis thaliana. The suspenso...Summary During embryogenesis, plants are thought to use a mechanism that allows the suspensor to maintain its identity. Here, we reported that RPL18a is involved in this mechanism in Arabidopsis thaliana. The suspensor cells proliferated in rp118aB and formed a multicellular structure rather than undergo pro- grammed cell death, as in wild type. Suspensors of rpl18a expressed the embryo proper marker, DRN：： GFP, but not the suspensor marker, WOX8：：GFP. In addition, auxin accumulated throughout the suspensors of rpl18a proembryos. Suspensor-specific expression of RPL18a could rescue the cell proliferation defects in rpl18a suspensors. These findings supported a role for RPL18a in maintaining suspensor identity.展开更多
An organocatalytic methodology toward the atroposelective construction of axially chiral nonsymmetric biaryltriols has been successfully developed.A quinine-derived thiourea-catalyzed intramolecular reaction using VQM...An organocatalytic methodology toward the atroposelective construction of axially chiral nonsymmetric biaryltriols has been successfully developed.A quinine-derived thiourea-catalyzed intramolecular reaction using VQM(vinylidene ortho-quinone methides)intermediates enabled efficient access to a class of axially chiral nonsymmetric biaryltriols with up to 98%yield and 99%ee.展开更多
An atroposelectively diversity-oriented synthetic strategy was developed for the divergent synthesis of axially chiral heterocycles through organocatalytic asymmetric intramolecular annulation of alkyne via vinylidene...An atroposelectively diversity-oriented synthetic strategy was developed for the divergent synthesis of axially chiral heterocycles through organocatalytic asymmetric intramolecular annulation of alkyne via vinylidene ortho-quinone methides(VQMs).The methodology reported herein was characterized by rapid reactions(most completed in seconds),high stereocontrol(up to 98%ee),and broad substrate scope(60 examples of different skeletal types,stereogenicelements,andring sizes).展开更多
基金supported by National Natural Science Foundation of China(No.12075281)the National Magnetic Confinement Fusion Research Program of China(Nos.2017YFE0301104 and 2017YFE0301105)Important Projects of Collaborative Innovation of the Hefei Science Center,CAS(No.2021HSC-CIP007)。
文摘A new multi-band and high-speed endoscope diagnostic for the observation of visible light has been successfully developed on the Experimental Advanced Superconducting Tokamak.The mirror with an aperture is designed at the head of the optical system.Based on two dichroic mirrors,the system is divided into three imaging mirror groups with different bands,i.e.B(380-500 nm),G(500-580 nm)and R(580-750 nm)bands,and its focal length is 16 mm with a relatively large aperture of D/f=1:4.The spatial resolution is less than 5 mm near the object distance of 1750 mm with the camera NAC ACS-1 M60.This optical system will be used to contrastively study both the spatial distribution and time evolution of different impurities in the same field of view.The experimental results confirm that it can be applied to the recognition of plasma boundary and related physical research.
基金supported by the Fund of Key Basic Theory Research of Ministry of Science and Technology of China(2013CB945100)the National Natural Science Foundation of China(31570317,31270362)
文摘The specific functions of the genes encoding arginine biosynthesis enzymes in plants are not well characterized. We report the isolation and characterization of Arabidopsis thaliana N-acetylglutamate kinase （NAGK）, which catalyzes the second step of arginine biosynthesis. NAGK is a plastid-localized protein and is expressed during most developmental processes in Arabidopsis. Heterologous expression of the Arabidopsis NAGK gene in a NAGK-deficient Escherichia coli strain fully restores bacterial growth on arginine-deficient medium, nagk mutant pollen tubes grow more slowly than wild type pollen tubes and the phenotype is restored by either specifically through complementation by NAGK in pollen, or exogenous supplementation of arginine, nagk female gametophytes are defective in micropylar pollen tube guidance due to the fact that female gametophyte cell fate specification was specifically affected. Expression of NAGK in synergid cells rescues the defect of nagk female gametophytes. Loss- of-function of NAGK results in Arabidopsis embryos not developing beyond the four-celled embryo stage. The embryo-defective phenotype in nagk/NAGK plants cannot be rescued by watering nagk/NAGK plants with arginine or ornithine supplementation. In conclusion, our results reveal a novel role of NAGK and arginine in regulating gametophyte function and embryo development, and provide valuable insights into arginine transport during embryo development.
基金supported by the Fundamental Research Funds for the Central Universities in China(No. CQDXWL-2014-2003)the Scientific Research Foundation of China(No. 21402016)Graduate Scientific Research and Innovation Foundation of Chongqing, China (Nos. CYS17044, CYB16032)
文摘A mild and efficient enantioselective one-pot synthesis of β-sulfonyl ketones and trisubstituted tetrahydrothiophenes via introducing 1,4-dithiane-2,5-diol to the simple kinetic resolution of β-sulfonyl ketones has been described herein. The one-pot reaction sequence including kinetic resolution and cascade sulfa-Michael/Aldol reaction proceeded successively to afford corresponding sulfonyl ketones and tetrahydrothiophenes with high enantioselectivities（85%-98% ee and 84%-95% ee）.
基金supported by the National Natural Science Foundation of China(31570317 and 31270362)
文摘Summary During embryogenesis, plants are thought to use a mechanism that allows the suspensor to maintain its identity. Here, we reported that RPL18a is involved in this mechanism in Arabidopsis thaliana. The suspensor cells proliferated in rp118aB and formed a multicellular structure rather than undergo pro- grammed cell death, as in wild type. Suspensors of rpl18a expressed the embryo proper marker, DRN：： GFP, but not the suspensor marker, WOX8：：GFP. In addition, auxin accumulated throughout the suspensors of rpl18a proembryos. Suspensor-specific expression of RPL18a could rescue the cell proliferation defects in rpl18a suspensors. These findings supported a role for RPL18a in maintaining suspensor identity.
基金This study was supported by the Chongqing Science and Technology Commission(Project No.2020CDJQY-Z002)the Scientific Research Foundation of China(Grant No:21922101,22001025,21901026).
文摘An organocatalytic methodology toward the atroposelective construction of axially chiral nonsymmetric biaryltriols has been successfully developed.A quinine-derived thiourea-catalyzed intramolecular reaction using VQM(vinylidene ortho-quinone methides)intermediates enabled efficient access to a class of axially chiral nonsymmetric biaryltriols with up to 98%yield and 99%ee.
基金provided by the Zhejiang Provincial Natural Science Foundation of China(grant no.LQ19B020003)the Scientific Research Foundation of China(grant nos.21922101,21772018,and 21901026)the Fundamental Research Funds for the Central Universities(project no.2020CQJQY-Z002).
文摘An atroposelectively diversity-oriented synthetic strategy was developed for the divergent synthesis of axially chiral heterocycles through organocatalytic asymmetric intramolecular annulation of alkyne via vinylidene ortho-quinone methides(VQMs).The methodology reported herein was characterized by rapid reactions(most completed in seconds),high stereocontrol(up to 98%ee),and broad substrate scope(60 examples of different skeletal types,stereogenicelements,andring sizes).
