Due to many remarkable physical and chemical properties,two-dimensional(2D)nanomaterials have become a hot spot in the field of condensed matter physics.In this paper,we have studied the structural,mechanical,and elec...Due to many remarkable physical and chemical properties,two-dimensional(2D)nanomaterials have become a hot spot in the field of condensed matter physics.In this paper,we have studied the structural,mechanical,and electronic properties of the 2D GaInO_(3)system by first-principles method.We find that 2D Ga InO_(3)can exist stably at ambient condition.Molecular dynamic simulations show that GaInO_(3)-sheet has excellent thermal stability and is stable up to1100 K.Electronic structural calculations show that GaInO_(3)-sheet has a band gap of 1.56 eV,which is close to the ideal band gap of solar cell materials,demonstrating great potential in future photovoltaic application.In addition,strain effect studies show that the GaInO_(3)-sheet structure always exhibits a direct band gap under biaxial compressive strain,and as the biaxial compressive strain increases,the band gap gradually decreases until it is converted into metal.While biaxial tensile strain can cause the 2D material to transform from a direct band gap semiconductor into an indirect band gap semiconductor,and even to metal.Our research expands the application of the Ga InO_(3)system,which may have potential application value in electronic devices and solar energy.展开更多
近年来,基于成簇的规律间隔短回文重复序列及其相关系统(Clustered regularly interspaced short palindromic repeats/CRISPR-associated protein,CRISPR/Cas)的基因编辑技术飞速发展,该系统可以利用同源定向重组(Homology directed re...近年来,基于成簇的规律间隔短回文重复序列及其相关系统(Clustered regularly interspaced short palindromic repeats/CRISPR-associated protein,CRISPR/Cas)的基因编辑技术飞速发展,该系统可以利用同源定向重组(Homology directed repair,HDR)来完成其介导的精准编辑,但效率极低,限制了其在农业和生物医学等领域上的推广应用。基于CRISPR/Cas系统的DNA碱基编辑技术作为一种新兴的基因组编辑技术,能在不产生双链断裂的情况下实现碱基的定向突变,相对于CRISPR/Cas介导的HDR编辑具有更高的编辑效率和特异性。目前,已开发出了可将C碱基突变为T碱基的胞嘧啶碱基编辑器(Cytidine base editors,CBE),将A碱基突变为G碱基的腺嘌呤碱基编辑器(Adenine base editors,ABE),以及可实现碱基任意变换和小片段精准插入和缺失的Prime编辑器(Prime editors,PE)。另外,能实现C到G颠换的糖基化酶碱基编辑器(Glycosylase base editors,GBE)以及能同时编辑A和C两种底物的双碱基编辑器也已被开发出来。文中主要综述了几种DNA碱基编辑器的开发历程、研究进展及各自优点和局限性;介绍了DNA碱基编辑技术在生物医学以及农业中的成功应用案例,以期为DNA碱基编辑器的进一步优化和选择应用提供借鉴。展开更多
Gadolinium oxide(Gd2O3) film has potential as a candidate gate dielectric to replace Hf O2. In this work,we provide a simple method by trace Ta(~1%) doping to significantly improve the dielectric properties of Gd2O3 f...Gadolinium oxide(Gd2O3) film has potential as a candidate gate dielectric to replace Hf O2. In this work,we provide a simple method by trace Ta(~1%) doping to significantly improve the dielectric properties of Gd2O3 film. And effects of annealing temperatures of Ta-doped Gd2O3(GTO) films are investigated in detail. Results show that GTO film annealed at 500℃ exhibits excellent performance as a novel gate dielectric material for integrated circuit, showing a small surface roughness of 0.199 nm, a large band gap of 5.45 e V, a high dielectric constant(k) of 21.2 and a low leakage current density(Jg) of 2.10 × 10^-3A/cm^2.All properties of GTO films are superior to pure Gd2O3 films and these GTO films meet the requirements for next-generation gate dielectrics. In addition, impedance spectrum is first used to analyze the equivalent circuit of GTO based metal-oxide-semiconductor(MOS) capacitors, which represents a new insight to understand observed electrical behaviors.展开更多
Homo!ogy-directed repair(HDR)is one of two major DNA repair pathways to mend the double-strand breaks(DSBs)formed in the genome(Liang et al.,1998;Pardo et al.,2009).Although less efficient compared with another DNA re...Homo!ogy-directed repair(HDR)is one of two major DNA repair pathways to mend the double-strand breaks(DSBs)formed in the genome(Liang et al.,1998;Pardo et al.,2009).Although less efficient compared with another DNA repair pathway,nonhomologous end joining(NHEJ),HDR is a type of precise repair to restore DNA damage and sustain genomic stability(Pardo et al.,2009;Ceccaldi et al.,2016).By contrast,NHEJ usually introduces mutations into the repaired site,thus probably harming the genomic integrity(Lieber et al.,2003).The error-free property enables HDR to be harnessed to correct a faulty mutation for therapeutic purpose in cells or in the body(Wu et al.,2013).In add让ion,HDR possesses great potential in the generation of genome-edited animals with precise genetic modifications,such as point mutation,DNA replacement,and DNA insertion in a specific genomic site(Wang et al.,2013).However,the low repair frequency mediated by HDR significantly limits让s application for efficient gene correction or establishment of various genetically modified animal models.Currently,multiple site-specific endonucleases have emerged as highly efficient tools to create targeted DSBs and markedly promote subsequent DNA repair either via HDR or NHEJ(Gaj et al.,2013).Nonetheless,the HDR-mediated modifications following the cleavage of engineering nucleases are still inefficient,usually with an efficiency less than 20%in cultured mammalian cells and embryos(Mali et al..2013;Wang et al.,2013;Yang et al.,2013).展开更多
Developing redox switches that not only perform specific mechanical movements but also drive important chemical reactions is important but a great challenge.Herein,we report a redox pair of cobalt species(Co^(Ⅲ)/Co^(...Developing redox switches that not only perform specific mechanical movements but also drive important chemical reactions is important but a great challenge.Herein,we report a redox pair of cobalt species(Co^(Ⅲ)/Co^(Ⅱ))that switches through photo-dehydrogenation of alcohol and hydrogenation of azo-ligand.The cobalt species is equipped with a flexible azo-ligand containing two bulky planar substituents.A planar oxidated sate(Co^(Ⅲ)species)can be photo-reduced to a saddle-like reduced state(Co^(Ⅱ))with alcohol molecules as electron donors,and in turn the Co^(Ⅲ)species can be recovered with azo-ligand as oxidant under acidic surrounding.Both the redox states of the pair are isolated and characterized by single crystal X-ray diffraction.In the switching cycle,alcohol is oxidized to aldehyde by azo-ligand through proton coupled electron transfer and the cobalt complex acts as a redox catalyst.These results provide important insights into alcohol dehydrogenation catalyzed by redox complexes.展开更多
Duchenne muscular dystrophy(DMD)is a severe neuromuscular disorder caused by mutations in the dystrophin gene,which encodes the essential protein dystrophin.This genetic condition,affecting approximately 1 in 5000 mal...Duchenne muscular dystrophy(DMD)is a severe neuromuscular disorder caused by mutations in the dystrophin gene,which encodes the essential protein dystrophin.This genetic condition,affecting approximately 1 in 5000 male births worldwide(Birnkrant et al.,2018),is characterized by progressive muscle weakness and wasting,leading to premature death in the second or third decade of life(Farini et al.,2016).The absence of dystrophin protein causes instability in the sarcolemma,which predisposes individuals to myonecrosis and activation of inflammatory signaling cascades.Unfortunately,there is currently no effective cure for DMD,and glucocorticoid steroids are commonly used in clinical settings to delay symptom development(Merlini et al.,2003).展开更多
N-Ethylcarbazole(NEC)is one of the most promising liquid organic hydrogen carriers(LOHCs),but its application is limited by sluggish kinetics due to lack of high-efficiency,low-cost catalysts.This work reports a cobal...N-Ethylcarbazole(NEC)is one of the most promising liquid organic hydrogen carriers(LOHCs),but its application is limited by sluggish kinetics due to lack of high-efficiency,low-cost catalysts.This work reports a cobalt(Co)-based catalyst promoted by nonstoichiometric yttrium hydride(YH_(3−x))to achieve high-efficiency,reversible hydrogen storage in NEC,with>5.5 wt%reversible hydrogen storage capacity could be achieved below 473 K,and with good kinetics.The YH_(3−x)-promoted Co-based catalyst is the first non-noble metal catalyst with high activity for NEC hydrogenation and 12H-NEC dehydrogenation reactions.A mechanistic study suggests that YH_(3−x)facilitates the reversible hydrogen transfer both in the hydrogenation and the dehydrogenation reactions.The nonstoichiometric YH_(3−x)contained both lattice H and H vacancies with tunable H chemical potential serve as the H donor and H acceptor for reversible hydrogen transfer.Our results support the practical application of LOHCs and inspire new approaches for the utilization of conventional metal hydrides to promote versatile H transfer reactions.展开更多
Metal-organic frameworks showing successive magnetic ordering are far less common than inorganic compounds.Here,we report two metal-organic frameworks[Co^Ⅱ(ox)(bphy)·0.1(DMF)·0.1(Me OH)]n(1)and[Co3^Ⅱ(ox)3(...Metal-organic frameworks showing successive magnetic ordering are far less common than inorganic compounds.Here,we report two metal-organic frameworks[Co^Ⅱ(ox)(bphy)·0.1(DMF)·0.1(Me OH)]n(1)and[Co3^Ⅱ(ox)3(bphy)2(DMF)2]n(2)comprised of zigzag and necklace Co^Ⅱ-ladders,respectively.Together with a previously reported compound[Co^Ⅱ(ox)(bphy)·0.2(DMF)]n(3)consisting of spiraling zigzag Co^Ⅱ-ladders,these three compounds provide a good system for comparative structural and magnetic studies.Comprehensive magnetic analysis reveals that the three compounds undergo long-range magnetic ordering at^2.6 K but exhibit vastly different short-range magnetic correlations:compound 1 shows short-range spin-canted antiferromagnetism ordering at^14.0 K;compound 2 demonstrates successive short-range antiferromagnetism ordering at^15.5and^12.6 K;compound 3 shows slow magnetic relaxation with Tb≈4.6 K.These results demonstrate long-range magnetic ordering is readily accessible in the frameworks of ox^2-bridging Co^Ⅱ-ladders linked by bphy,where short-range magnetic correlations can be systematicly tuned by the Co^Ⅱ-ladder structures.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11847094,61764001,and U1404212)the Cheung Kong Scholars Programme of China+2 种基金the Program of Changjiang Scholars and Innovative Research Team in University,China(Grant No.IRT1132)Open Project of State Key Laboratory of Superhard Materials(Jilin University)China(Grant No.201703)
文摘Due to many remarkable physical and chemical properties,two-dimensional(2D)nanomaterials have become a hot spot in the field of condensed matter physics.In this paper,we have studied the structural,mechanical,and electronic properties of the 2D GaInO_(3)system by first-principles method.We find that 2D Ga InO_(3)can exist stably at ambient condition.Molecular dynamic simulations show that GaInO_(3)-sheet has excellent thermal stability and is stable up to1100 K.Electronic structural calculations show that GaInO_(3)-sheet has a band gap of 1.56 eV,which is close to the ideal band gap of solar cell materials,demonstrating great potential in future photovoltaic application.In addition,strain effect studies show that the GaInO_(3)-sheet structure always exhibits a direct band gap under biaxial compressive strain,and as the biaxial compressive strain increases,the band gap gradually decreases until it is converted into metal.While biaxial tensile strain can cause the 2D material to transform from a direct band gap semiconductor into an indirect band gap semiconductor,and even to metal.Our research expands the application of the Ga InO_(3)system,which may have potential application value in electronic devices and solar energy.
文摘近年来,基于成簇的规律间隔短回文重复序列及其相关系统(Clustered regularly interspaced short palindromic repeats/CRISPR-associated protein,CRISPR/Cas)的基因编辑技术飞速发展,该系统可以利用同源定向重组(Homology directed repair,HDR)来完成其介导的精准编辑,但效率极低,限制了其在农业和生物医学等领域上的推广应用。基于CRISPR/Cas系统的DNA碱基编辑技术作为一种新兴的基因组编辑技术,能在不产生双链断裂的情况下实现碱基的定向突变,相对于CRISPR/Cas介导的HDR编辑具有更高的编辑效率和特异性。目前,已开发出了可将C碱基突变为T碱基的胞嘧啶碱基编辑器(Cytidine base editors,CBE),将A碱基突变为G碱基的腺嘌呤碱基编辑器(Adenine base editors,ABE),以及可实现碱基任意变换和小片段精准插入和缺失的Prime编辑器(Prime editors,PE)。另外,能实现C到G颠换的糖基化酶碱基编辑器(Glycosylase base editors,GBE)以及能同时编辑A和C两种底物的双碱基编辑器也已被开发出来。文中主要综述了几种DNA碱基编辑器的开发历程、研究进展及各自优点和局限性;介绍了DNA碱基编辑技术在生物医学以及农业中的成功应用案例,以期为DNA碱基编辑器的进一步优化和选择应用提供借鉴。
基金supported financially by the Project of Ministry of Science and Technology of the People’s Republic of China (No. 2017YFB0405902)the National Natural Science Foundation of China (Nos. 51431001, 51771002, 21771006, U1607126 and 21621061)Beijing Municipal Commission of Science and Technology (No. Z17110000091702)
文摘Gadolinium oxide(Gd2O3) film has potential as a candidate gate dielectric to replace Hf O2. In this work,we provide a simple method by trace Ta(~1%) doping to significantly improve the dielectric properties of Gd2O3 film. And effects of annealing temperatures of Ta-doped Gd2O3(GTO) films are investigated in detail. Results show that GTO film annealed at 500℃ exhibits excellent performance as a novel gate dielectric material for integrated circuit, showing a small surface roughness of 0.199 nm, a large band gap of 5.45 e V, a high dielectric constant(k) of 21.2 and a low leakage current density(Jg) of 2.10 × 10^-3A/cm^2.All properties of GTO films are superior to pure Gd2O3 films and these GTO films meet the requirements for next-generation gate dielectrics. In addition, impedance spectrum is first used to analyze the equivalent circuit of GTO based metal-oxide-semiconductor(MOS) capacitors, which represents a new insight to understand observed electrical behaviors.
基金supported by grants from Guangdong Science and Technology Department (2017B020201009)the National Natural Science Foundation of China (31772555)the National Science and Technology Major Project for Breeding of New Transgenic Organisms (2016ZX08006002)
文摘Homo!ogy-directed repair(HDR)is one of two major DNA repair pathways to mend the double-strand breaks(DSBs)formed in the genome(Liang et al.,1998;Pardo et al.,2009).Although less efficient compared with another DNA repair pathway,nonhomologous end joining(NHEJ),HDR is a type of precise repair to restore DNA damage and sustain genomic stability(Pardo et al.,2009;Ceccaldi et al.,2016).By contrast,NHEJ usually introduces mutations into the repaired site,thus probably harming the genomic integrity(Lieber et al.,2003).The error-free property enables HDR to be harnessed to correct a faulty mutation for therapeutic purpose in cells or in the body(Wu et al.,2013).In add让ion,HDR possesses great potential in the generation of genome-edited animals with precise genetic modifications,such as point mutation,DNA replacement,and DNA insertion in a specific genomic site(Wang et al.,2013).However,the low repair frequency mediated by HDR significantly limits让s application for efficient gene correction or establishment of various genetically modified animal models.Currently,multiple site-specific endonucleases have emerged as highly efficient tools to create targeted DSBs and markedly promote subsequent DNA repair either via HDR or NHEJ(Gaj et al.,2013).Nonetheless,the HDR-mediated modifications following the cleavage of engineering nucleases are still inefficient,usually with an efficiency less than 20%in cultured mammalian cells and embryos(Mali et al..2013;Wang et al.,2013;Yang et al.,2013).
基金supported by the National Natural Science Foundation of China(Nos.21871262,21805275 and 21901242)the Natural Science Foundation of Fujian Province(No.2019J01130)the Recruitment Program of Global Youth Experts。
文摘Developing redox switches that not only perform specific mechanical movements but also drive important chemical reactions is important but a great challenge.Herein,we report a redox pair of cobalt species(Co^(Ⅲ)/Co^(Ⅱ))that switches through photo-dehydrogenation of alcohol and hydrogenation of azo-ligand.The cobalt species is equipped with a flexible azo-ligand containing two bulky planar substituents.A planar oxidated sate(Co^(Ⅲ)species)can be photo-reduced to a saddle-like reduced state(Co^(Ⅱ))with alcohol molecules as electron donors,and in turn the Co^(Ⅲ)species can be recovered with azo-ligand as oxidant under acidic surrounding.Both the redox states of the pair are isolated and characterized by single crystal X-ray diffraction.In the switching cycle,alcohol is oxidized to aldehyde by azo-ligand through proton coupled electron transfer and the cobalt complex acts as a redox catalyst.These results provide important insights into alcohol dehydrogenation catalyzed by redox complexes.
基金supported by grants from National Natural Science Foundation of China(82202052,82230039,U2005201,81870902,82001217,31925016,and 82021001)Major Scientific Research Project for Middle-age and Youth of Fujian Provincial Health Commission grant(2021ZQNZD003)+2 种基金Major Scientific Research Project of Fujian Provincial Health Commission grant(2022ZD01002)Joint Funds for the Innovation of Science and Technology of Fujian Province(2018Y9082)the Youth Scientific Research。
文摘Duchenne muscular dystrophy(DMD)is a severe neuromuscular disorder caused by mutations in the dystrophin gene,which encodes the essential protein dystrophin.This genetic condition,affecting approximately 1 in 5000 male births worldwide(Birnkrant et al.,2018),is characterized by progressive muscle weakness and wasting,leading to premature death in the second or third decade of life(Farini et al.,2016).The absence of dystrophin protein causes instability in the sarcolemma,which predisposes individuals to myonecrosis and activation of inflammatory signaling cascades.Unfortunately,there is currently no effective cure for DMD,and glucocorticoid steroids are commonly used in clinical settings to delay symptom development(Merlini et al.,2003).
基金This research was made possible as a result of a generous grant from MOST of China(no.2018YFB1502102)NSFC(nos.21771006,51771002,and 51971004).
文摘N-Ethylcarbazole(NEC)is one of the most promising liquid organic hydrogen carriers(LOHCs),but its application is limited by sluggish kinetics due to lack of high-efficiency,low-cost catalysts.This work reports a cobalt(Co)-based catalyst promoted by nonstoichiometric yttrium hydride(YH_(3−x))to achieve high-efficiency,reversible hydrogen storage in NEC,with>5.5 wt%reversible hydrogen storage capacity could be achieved below 473 K,and with good kinetics.The YH_(3−x)-promoted Co-based catalyst is the first non-noble metal catalyst with high activity for NEC hydrogenation and 12H-NEC dehydrogenation reactions.A mechanistic study suggests that YH_(3−x)facilitates the reversible hydrogen transfer both in the hydrogenation and the dehydrogenation reactions.The nonstoichiometric YH_(3−x)contained both lattice H and H vacancies with tunable H chemical potential serve as the H donor and H acceptor for reversible hydrogen transfer.Our results support the practical application of LOHCs and inspire new approaches for the utilization of conventional metal hydrides to promote versatile H transfer reactions.
基金the National Natural Science Foundation of China(21871262,21805257,21901242)the Natural Science Foundation of Fujian Province(2019J01130)the Recruitment Program of Global Youth Experts。
文摘Metal-organic frameworks showing successive magnetic ordering are far less common than inorganic compounds.Here,we report two metal-organic frameworks[Co^Ⅱ(ox)(bphy)·0.1(DMF)·0.1(Me OH)]n(1)and[Co3^Ⅱ(ox)3(bphy)2(DMF)2]n(2)comprised of zigzag and necklace Co^Ⅱ-ladders,respectively.Together with a previously reported compound[Co^Ⅱ(ox)(bphy)·0.2(DMF)]n(3)consisting of spiraling zigzag Co^Ⅱ-ladders,these three compounds provide a good system for comparative structural and magnetic studies.Comprehensive magnetic analysis reveals that the three compounds undergo long-range magnetic ordering at^2.6 K but exhibit vastly different short-range magnetic correlations:compound 1 shows short-range spin-canted antiferromagnetism ordering at^14.0 K;compound 2 demonstrates successive short-range antiferromagnetism ordering at^15.5and^12.6 K;compound 3 shows slow magnetic relaxation with Tb≈4.6 K.These results demonstrate long-range magnetic ordering is readily accessible in the frameworks of ox^2-bridging Co^Ⅱ-ladders linked by bphy,where short-range magnetic correlations can be systematicly tuned by the Co^Ⅱ-ladder structures.
