Realizing ferromagnetic semiconductors with high Curie temperature TC is still a challenge in spintronics.Recent experiments have reported two-dimensional(2D)room temperature ferromagnetic metals,such as monolayer Cr_...Realizing ferromagnetic semiconductors with high Curie temperature TC is still a challenge in spintronics.Recent experiments have reported two-dimensional(2D)room temperature ferromagnetic metals,such as monolayer Cr_(3)Te_(6).In this paper,through density functional theory(DFT)calculations,we propose a method to obtain 2D high TC ferromagnetic semiconductors through element replacement in these ferromagnetic metals.We predict that monolayer(Cr_(4/6),Mo_(2/6))_(3)Te_(6),created via element replacement in monolayer Cr_(3)Te_(6),is a room-temperature ferromagnetic semiconductor exhibiting a band gap of 0.34 eV and a TC of 384 K.Our analysis reveals that the metal-to-semiconductor transition stems from the synergistic interplay of Mo-induced lattice distortion,which resolves band overlap,and the electronic contributions of Mo dopants,which further drive the formation of a distinct band gap.The origin of the high TC is traced to strong superexchange coupling between magnetic ions,analyzed via the superexchange model with DFT and Wannier function calculations.Considering the fast developments in fabrication and manipulation of 2D materials,our theoretical results propose an approach to explore high-temperature ferromagnetic semiconductors derived from experimentally obtained 2D high-temperature ferromagnetic metals through element replacement.展开更多
Magnetic semiconductors have been demonstrated to work at low temperatures, but not yet at room temperature for spin electronic applications. In contrast to the p-type diluted magnetic semiconductors, n-type diluted m...Magnetic semiconductors have been demonstrated to work at low temperatures, but not yet at room temperature for spin electronic applications. In contrast to the p-type diluted magnetic semiconductors, n-type diluted magnetic semiconductors are few. Using a combined method of the density function theory and quantum Monte Carlo simulation, we briefly discuss the recent progress to obtain diluted magnetic semiconductors with both p- and n-type carriers by choosing host semiconductors with a narrow band gap. In addition, the recent progress on two-dimensional intrinsic magnetic semiconductors with possible room temperature ferromangetism and quantum anomalous Hall effect are also discussed.展开更多
Magnetic semiconductors integrate the dual characteristics of magnets and semiconductors.It is difficult to manufacture magnetic semiconductors that function at room temperature.Here,we review a series of our recent t...Magnetic semiconductors integrate the dual characteristics of magnets and semiconductors.It is difficult to manufacture magnetic semiconductors that function at room temperature.Here,we review a series of our recent theoretical predictions on room-temperature ferromagnetic semiconductors.Since the creation of two-dimensional(2D)magnetic semiconductors in 2017,there have been numerous developments in both experimental and theoretical investigations.By density functional theory calculations and model analysis,we recently predicted several2D room-temperature magnetic semiconductors,including CrGeSe_(3)with strain,CrGeTe_(3)/PtSe_(2) heterostructure,and technetium-based semiconductors(TcSiTe_(3),TcGeSe_(3),and TcGeTe_(3)),as well as PdBr_(3)and PtBr_(3)with a potential room-temperature quantum anomalous Hall effect.Our findings demonstrated that the Curie temperature of these 2D ferromagnetic semiconductors can be dramatically enhanced by some external fields,such as strain,construction of heterostructure,and electric field.In addition,we proposed appropriate doping conditions for diluted magnetic semiconductors,and predicted the Cr doped GaSb and InSb as possible room-temperature magnetic semiconductors.展开更多
Indole alkaloids have attracted considerable attention from synthetic chemists and biochemists for their structural diversity and important biological activities.Compared with traditional organic synthesis methods,the...Indole alkaloids have attracted considerable attention from synthetic chemists and biochemists for their structural diversity and important biological activities.Compared with traditional organic synthesis methods,the strategy of using cytochrome P450s'extraordinary abilities to selectively activate carbon-hydrogen bonds to assist in the synthesis of various indole alkaloids has the characteristics of short synthetic route,mild conditions and high atomic economy.Here,we utilized P450 monooxygenases HinD and TleB to synthesize a novel 6/5/8 tricyclic product from(S)-N-((S)-1-(4-fluoro-1H-indol-3-yl)-3-hydroxypropan-2-yl)-2-mercapto-3-methylbutanamide through the substrate structure-directed strategy.TleB was more effective in catalyzing C–S coupling,and was used to synthesize a series of 6/5/8 tricyclic indololactam derivatives to provide drug candidates.Interestingly,the S–S coupling product was observed in HinD catalysis,which was a minor product in the wild-type TleB catalysis.With the help of protein engineering,we accurately regulated the catalytic flow and reversed the selectivity of TleB to obtain the S–S coupling product.At the same time,the reaction mechanism was reasonably speculated by means of site blocking and protein-substrate complex analysis.展开更多
Realizing ferromagnetic semiconductors with high Curie temperature TC remains a challenge in spintronics.Recent experiments have obtained some two-dimensional(2D)room temperature ferromagnetic metals,such as monolayer...Realizing ferromagnetic semiconductors with high Curie temperature TC remains a challenge in spintronics.Recent experiments have obtained some two-dimensional(2D)room temperature ferromagnetic metals,such as monolayers CrS_(2)and VSe_(2).Inspired by the recent experimental progress on the nanotubes based on 2D van der Waals non-magnetic transition-metal dichalcogenides,magnetic nanotubes based on monolayer ferromagnetic materials are highly possible.Here,by the density functional theory calculations,we proposed a way to obtain a high TC ferromagnetic semiconductor in magnetic nanotubes.Some high TC ferromagnetic semiconductors are predicted in the MX_(2)nanotubes(M=V,Cr,Mn,Fe,Co,Ni;X=S,Se,Te),including CrS_(2)and CrTe_(2)zigzag nanotubes with a diameter of 18 unit cells,showing TC above 300 K.In addition,due to the strain gradient in the walls of nanotubes,an electrical polarization at the level of 0.1 eV/Åinward of the radial direction is obtained.Our results propose a way to obtain high-temperature ferromagnetic semiconducting nanotubes based on experimentally obtained 2D high TC ferromagnetic metals.展开更多
Comprehensive Summary.Atherosclerosis is a lipoprotein-driven disease.In-depth understanding of pathology and accurate identification are particularly important in clinical assessment and treatment due to the irrevers...Comprehensive Summary.Atherosclerosis is a lipoprotein-driven disease.In-depth understanding of pathology and accurate identification are particularly important in clinical assessment and treatment due to the irreversibility of atherosclerotic plaque formation.Atherosclerosis is not only accompanied by lipid droplets accumulation but also closely related to inflammation,which is accompanied by excessive reactive oxygen species(ROS)and changes in microenvironment.However,there is still a lack of a simple and rapid detection platform to simultaneously evaluate multiple indicators of atherosclerosis in multiple channels.In this study,we propose a multicolor imaging probe Cy7P-B for polarity,H_(2)O_(2) and lipid droplets to evaluate atherosclerotic plaques in vivo.Cy7P-B is sensitive to environmental polarity and can monitor polarity changes by near-infrared ratio.Moreover,Cy7P-B has H_(2)O_(2)/lipid droplets dual-analyte sequential activation characteristics.Based on the multifunctional properties of Cy7P-B,the classical biomarkers of atherosclerotic plaque,lipid accumulation and up-regulation of oxidative stress are effectively detected in atherosclerotic plaques,and more importantly,the change of aortic polarity in atherosclerosis was detected for the first time.This work provides a general molecular design approach for multi-species imaging of AS,which is helpful for effective cardiovascular disease stewardship.展开更多
Large-Scale Language Models(LLMs)have initiated transformative changes in Traditional Chinese Medicine(TCM),yet existing LLM-based diagnostic approaches face challenges such as prolonged training cycles and high imple...Large-Scale Language Models(LLMs)have initiated transformative changes in Traditional Chinese Medicine(TCM),yet existing LLM-based diagnostic approaches face challenges such as prolonged training cycles and high implementation costs due to reliance on medical expertise.To address this,we propose a systematic framework integrating multimodal data and LLM technologies.First,we analyze bottlenecks in traditional diagnosis(e.g.,subjectivity)and modernization challenges.The framework leverages open-s ource foundation models(e.g.,Baichuan2,LLaMA)pre-trained on"symptom-syndrome-medication"associations,fine-tuned with clinical data to simulate diagnostic workflows.Key components include:(1)a Data Input Layer capturing tongue image features(via YOLOv5s6/U-Net),speech spectra,BERT-encoded inquiry texts,and pulse waveforms;(2)a Feature Fusion Layer constructing syndrome differentiation vectors through multimodal feature concatenation;and(3)a Prediction&Feedback Layer generating diagnostic probabilities with reinforcement learning based on clinical efficacy.Finally,we discuss critical issues,including risks of physician replacement,professional competence degradation,and liability attr ibution in diagnostic errors.This framework aims t o enhance TCM diagnostic efficiency while ensuring clinical reliability.展开更多
This study reports a deformation limit for the initiation of ductile fracture failure in fatigue-cracked circular hollow section （CHS） X- and K-joints subjected to brace axial tension. The proposed approach sets the...This study reports a deformation limit for the initiation of ductile fracture failure in fatigue-cracked circular hollow section （CHS） X- and K-joints subjected to brace axial tension. The proposed approach sets the deformation limit as the numerically computed crack driving force in a fatigue crack at the hot-spot location in the tubular joint reaches the material fracture toughness measured from standard fracture specimens. The calibration of the numerical procedure predicates on reported numerical computations on the crack driving force and previously published verification study against large-scale CHS X-joints with fatigue generated surface cracks. The development of the deformation limit includes a normalization procedure, which covers a wide range of the geometric parameters and material toughness levels. The lower-bound deformation limits thus developed follow a linear relationship with respect to the crack-depth ratio for both X- and K-joints. Comparison of the predicated deformation limit against experimental on cracked tubular X- and K- joints demonstrates the conservative nature of the proposed deformation limit. The proposed deformation limit, when extrapolated to a zero crack depth, provides an estimate on the deformation limits for intact X- and K-joints under brace axial loads.展开更多
To realize room temperature ferromagnetic(FM)semiconductors is still a challenge in spintronics.Many antiferromagnetic(AFM)insulators and semiconductors with high Neel temperature TN are obtained in experiments,such a...To realize room temperature ferromagnetic(FM)semiconductors is still a challenge in spintronics.Many antiferromagnetic(AFM)insulators and semiconductors with high Neel temperature TN are obtained in experiments,such as LaFeO_(3),BiFeO_(3),etc.High concentrations of magnetic impurities can be doped into these AFM materials,but AFM state with very tiny net magnetic moments was obtained in experiments because the magnetic impurities were equally doped into the spin up and down sublattices of the AFM materials.Here,we propose that the effective magnetic field provided by a FM substrate could guarantee the spin-dependent doping in AFM materials,where the doped magnetic impurities prefer one sublattice of spins,and the ferrimagnetic(FIM)materials are obtained.To demonstrate this proposal,we study the Mn-doped AFM insulator LaFeO_(3)with FM substrate of Fe metal by the density functional theory(DFT)calculations.展开更多
Dear Editor, Triacylglycerols （triglycerides） （TAGs）, as the major storage forms of energy, mainly are stored in adipocytes, myocytes, enterocytes, hepatocytes, and mammary epithelial cells in mammals, oilseeds i...Dear Editor, Triacylglycerols （triglycerides） （TAGs）, as the major storage forms of energy, mainly are stored in adipocytes, myocytes, enterocytes, hepatocytes, and mammary epithelial cells in mammals, oilseeds in plants, and lipid droplets in microorgan- isms （Yen et al., 2008）. Aside from energy storage, TAGs have essential functions in multiple physiological processes. In plants, TAGs are crucial for seed oil accumulation, germina- tion, and seedling development （Zhang et al., 2005, 2009）. Notably, TAGs derived from plants and microorganisms could serve as the feedstock for biofuels production （Deng et al., 2009）. Therefore, understanding of the molecular basis of TAGs bio- synthesis and storage is of considerable economic importance.展开更多
Unmanned aerial vehicle(UAV)has a rapid development over the last decade.However,an increasing number of severe flight collision events caused by explosive growth of UAV have drawn widespread concern.It is an importan...Unmanned aerial vehicle(UAV)has a rapid development over the last decade.However,an increasing number of severe flight collision events caused by explosive growth of UAV have drawn widespread concern.It is an important issue to investigate safety management approaches of UAVs to ensure safe and efficient operation.In this paper,we present a comprehensive overview of safety management approaches in large,middle and small scales.In large-scale safety management,path-planning problem is a crucial issue to ensure safety and ordered operation of UAVs globally.In middle-scale safety management,it is an important issue to study the conflict detection and resolution methods.And in small-scale safety management,real-time collision avoidance is the last line of ensuring safety.Moreover,a UAV can be regarded as a terminal device connected through communication and information network.Therefore,the enabling technologies,such as sensing,command and control communication,and collaborative decision-making control technology,have been studied in the last.展开更多
The recently discovered ATi_(3)Bi_(5)(A=Cs,Rb)exhibit intriguing quantum phenomena including superconductivity,electronic nematicity,and abundant topological states.ATi_(3)Bi_(5)present promising platforms for studyin...The recently discovered ATi_(3)Bi_(5)(A=Cs,Rb)exhibit intriguing quantum phenomena including superconductivity,electronic nematicity,and abundant topological states.ATi_(3)Bi_(5)present promising platforms for studying kagome superconductivity,band topology,and charge orders in parallel with AV3Sb5.In this work,we comprehensively analyze various properties of ATi_(3)Bi_(5)covering superconductivity under pressure and doping,band topology under pressure,thermal conductivity,heat capacity,electrical resistance,and spin Hall conductivity(SHC)using first-principles calculations.Calculated superconducting transition temperature(Tc)of CsTi_(3)Bi_(5)and RbTi_(3)Bi_(5)at ambient pressure are about 1.85 and 1.92 K.When subject to pressure,Tc of CsTi_(3)Bi_(5)exhibits a special valley and dome shape,which arises from quasi-two-dimensional compression to three-dimensional isotropic compression within the context of an overall decreasing trend.Furthermore,Tc of RbTi_(3)Bi_(5)can be effectively enhanced up to 3.09 K by tuning the kagome van Hove singularities(VHSs)and flat band through doping.Pressures can also induce abundant topological surface states at the Fermi energy(EF)and tune VHSs across EF.Additionally,our transport calculations are in excellent agreement with recent experiments,confirming the absence of charge density wave.Notably,SHC of CsTi_(3)Bi_(5)can reach up to 226h·(e·Ω·cm)^(-1)at EF.Our work provides a timely and detailed analysis of the rich physical properties for ATi_(3)Bi_(5),offering valuable insights for further experimental verifications and investigations in this field.展开更多
基金supported by the National Key R&D Program of China(Grant No.2022YFA1405100)Chinese Academy of Sciences Project for Young Scientists in Basic Research(Grant No.YSBR-030)+3 种基金the Basic Research Program of the Chinese Academy of Sciences Based on Major Scientific Infrastructures(Grant No.JZHKYPT-2021-08)GS was supported in part by the Innovation Program for Quantum Science and Technology(Grant No.2024ZD03005)the National Natural Science Foundation of China(Grant No.12447101)Chinese Academy of Sciences.
文摘Realizing ferromagnetic semiconductors with high Curie temperature TC is still a challenge in spintronics.Recent experiments have reported two-dimensional(2D)room temperature ferromagnetic metals,such as monolayer Cr_(3)Te_(6).In this paper,through density functional theory(DFT)calculations,we propose a method to obtain 2D high TC ferromagnetic semiconductors through element replacement in these ferromagnetic metals.We predict that monolayer(Cr_(4/6),Mo_(2/6))_(3)Te_(6),created via element replacement in monolayer Cr_(3)Te_(6),is a room-temperature ferromagnetic semiconductor exhibiting a band gap of 0.34 eV and a TC of 384 K.Our analysis reveals that the metal-to-semiconductor transition stems from the synergistic interplay of Mo-induced lattice distortion,which resolves band overlap,and the electronic contributions of Mo dopants,which further drive the formation of a distinct band gap.The origin of the high TC is traced to strong superexchange coupling between magnetic ions,analyzed via the superexchange model with DFT and Wannier function calculations.Considering the fast developments in fabrication and manipulation of 2D materials,our theoretical results propose an approach to explore high-temperature ferromagnetic semiconductors derived from experimentally obtained 2D high-temperature ferromagnetic metals through element replacement.
基金supported by NSFC (Grant No. Y81Z01A1A9)CAS (Grant No. Y929013EA2)+3 种基金UCAS (Grant No.110200M208)the Strategic Priority Research Program of CAS (Grant No. XDB28000000)the National Key R&D Program of China (Grant No.11834014)Beijing Municipal Science & Technology Commission (Grant No. Z181100004218001)
文摘Magnetic semiconductors have been demonstrated to work at low temperatures, but not yet at room temperature for spin electronic applications. In contrast to the p-type diluted magnetic semiconductors, n-type diluted magnetic semiconductors are few. Using a combined method of the density function theory and quantum Monte Carlo simulation, we briefly discuss the recent progress to obtain diluted magnetic semiconductors with both p- and n-type carriers by choosing host semiconductors with a narrow band gap. In addition, the recent progress on two-dimensional intrinsic magnetic semiconductors with possible room temperature ferromangetism and quantum anomalous Hall effect are also discussed.
基金the National Natural Science Foundation of China(Grant Nos.12074378 and 11834014)the Beijing Natural Science Foundation(Grant No.Z190011)+3 种基金the National Key R&D Program of China(Grant No.2018YFA0305800)the Beijing Municipal Science and Technology Commission(Grant No.Z191100007219013)the Chinese Academy of Sciences(Grant Nos.YSBR-030 and Y929013EA2)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDB28000000 and XDB33000000)。
文摘Magnetic semiconductors integrate the dual characteristics of magnets and semiconductors.It is difficult to manufacture magnetic semiconductors that function at room temperature.Here,we review a series of our recent theoretical predictions on room-temperature ferromagnetic semiconductors.Since the creation of two-dimensional(2D)magnetic semiconductors in 2017,there have been numerous developments in both experimental and theoretical investigations.By density functional theory calculations and model analysis,we recently predicted several2D room-temperature magnetic semiconductors,including CrGeSe_(3)with strain,CrGeTe_(3)/PtSe_(2) heterostructure,and technetium-based semiconductors(TcSiTe_(3),TcGeSe_(3),and TcGeTe_(3)),as well as PdBr_(3)and PtBr_(3)with a potential room-temperature quantum anomalous Hall effect.Our findings demonstrated that the Curie temperature of these 2D ferromagnetic semiconductors can be dramatically enhanced by some external fields,such as strain,construction of heterostructure,and electric field.In addition,we proposed appropriate doping conditions for diluted magnetic semiconductors,and predicted the Cr doped GaSb and InSb as possible room-temperature magnetic semiconductors.
基金supported by the National Key Research and Development Program of China(2018YFA0903200 to H.S.)Wuhan University,Undergraduate Training Programs for Innovation and Entrepreneurship of Wuhan University to Y.L.+1 种基金the Science and Technology Commission of Shanghaithe National Natural Science Foundation of China(31900033,21ZR1433700)。
文摘Indole alkaloids have attracted considerable attention from synthetic chemists and biochemists for their structural diversity and important biological activities.Compared with traditional organic synthesis methods,the strategy of using cytochrome P450s'extraordinary abilities to selectively activate carbon-hydrogen bonds to assist in the synthesis of various indole alkaloids has the characteristics of short synthetic route,mild conditions and high atomic economy.Here,we utilized P450 monooxygenases HinD and TleB to synthesize a novel 6/5/8 tricyclic product from(S)-N-((S)-1-(4-fluoro-1H-indol-3-yl)-3-hydroxypropan-2-yl)-2-mercapto-3-methylbutanamide through the substrate structure-directed strategy.TleB was more effective in catalyzing C–S coupling,and was used to synthesize a series of 6/5/8 tricyclic indololactam derivatives to provide drug candidates.Interestingly,the S–S coupling product was observed in HinD catalysis,which was a minor product in the wild-type TleB catalysis.With the help of protein engineering,we accurately regulated the catalytic flow and reversed the selectivity of TleB to obtain the S–S coupling product.At the same time,the reaction mechanism was reasonably speculated by means of site blocking and protein-substrate complex analysis.
基金supported by National Key R&D Program of China(Grant No.2022YFA1405100)National Natural Science Foundation of China(Grant No.12074378)+1 种基金Chinese Academy of Sciences(Grants No.YSBR-030,No.JZHKYPT-2021-08,No.XDB33000000)supported in part by the Innovation Program for Quantum Science and Technology under Grant No.2024ZD03005 NSFC No.12447101 and CAS.
文摘Realizing ferromagnetic semiconductors with high Curie temperature TC remains a challenge in spintronics.Recent experiments have obtained some two-dimensional(2D)room temperature ferromagnetic metals,such as monolayers CrS_(2)and VSe_(2).Inspired by the recent experimental progress on the nanotubes based on 2D van der Waals non-magnetic transition-metal dichalcogenides,magnetic nanotubes based on monolayer ferromagnetic materials are highly possible.Here,by the density functional theory calculations,we proposed a way to obtain a high TC ferromagnetic semiconductor in magnetic nanotubes.Some high TC ferromagnetic semiconductors are predicted in the MX_(2)nanotubes(M=V,Cr,Mn,Fe,Co,Ni;X=S,Se,Te),including CrS_(2)and CrTe_(2)zigzag nanotubes with a diameter of 18 unit cells,showing TC above 300 K.In addition,due to the strain gradient in the walls of nanotubes,an electrical polarization at the level of 0.1 eV/Åinward of the radial direction is obtained.Our results propose a way to obtain high-temperature ferromagnetic semiconducting nanotubes based on experimentally obtained 2D high TC ferromagnetic metals.
基金the National Key Research and Development Program of China(2019YFA0210500)for H.S.Guangdong Basic and Applied Basic Research Foundation(Nos.2022A1515010133 and 2024A1515011373 to H.S.)the National Natural Science Foundation of China(No.31900033 to H.S.)forfinancial support.
文摘Comprehensive Summary.Atherosclerosis is a lipoprotein-driven disease.In-depth understanding of pathology and accurate identification are particularly important in clinical assessment and treatment due to the irreversibility of atherosclerotic plaque formation.Atherosclerosis is not only accompanied by lipid droplets accumulation but also closely related to inflammation,which is accompanied by excessive reactive oxygen species(ROS)and changes in microenvironment.However,there is still a lack of a simple and rapid detection platform to simultaneously evaluate multiple indicators of atherosclerosis in multiple channels.In this study,we propose a multicolor imaging probe Cy7P-B for polarity,H_(2)O_(2) and lipid droplets to evaluate atherosclerotic plaques in vivo.Cy7P-B is sensitive to environmental polarity and can monitor polarity changes by near-infrared ratio.Moreover,Cy7P-B has H_(2)O_(2)/lipid droplets dual-analyte sequential activation characteristics.Based on the multifunctional properties of Cy7P-B,the classical biomarkers of atherosclerotic plaque,lipid accumulation and up-regulation of oxidative stress are effectively detected in atherosclerotic plaques,and more importantly,the change of aortic polarity in atherosclerosis was detected for the first time.This work provides a general molecular design approach for multi-species imaging of AS,which is helpful for effective cardiovascular disease stewardship.
文摘Large-Scale Language Models(LLMs)have initiated transformative changes in Traditional Chinese Medicine(TCM),yet existing LLM-based diagnostic approaches face challenges such as prolonged training cycles and high implementation costs due to reliance on medical expertise.To address this,we propose a systematic framework integrating multimodal data and LLM technologies.First,we analyze bottlenecks in traditional diagnosis(e.g.,subjectivity)and modernization challenges.The framework leverages open-s ource foundation models(e.g.,Baichuan2,LLaMA)pre-trained on"symptom-syndrome-medication"associations,fine-tuned with clinical data to simulate diagnostic workflows.Key components include:(1)a Data Input Layer capturing tongue image features(via YOLOv5s6/U-Net),speech spectra,BERT-encoded inquiry texts,and pulse waveforms;(2)a Feature Fusion Layer constructing syndrome differentiation vectors through multimodal feature concatenation;and(3)a Prediction&Feedback Layer generating diagnostic probabilities with reinforcement learning based on clinical efficacy.Finally,we discuss critical issues,including risks of physician replacement,professional competence degradation,and liability attr ibution in diagnostic errors.This framework aims t o enhance TCM diagnostic efficiency while ensuring clinical reliability.
文摘This study reports a deformation limit for the initiation of ductile fracture failure in fatigue-cracked circular hollow section （CHS） X- and K-joints subjected to brace axial tension. The proposed approach sets the deformation limit as the numerically computed crack driving force in a fatigue crack at the hot-spot location in the tubular joint reaches the material fracture toughness measured from standard fracture specimens. The calibration of the numerical procedure predicates on reported numerical computations on the crack driving force and previously published verification study against large-scale CHS X-joints with fatigue generated surface cracks. The development of the deformation limit includes a normalization procedure, which covers a wide range of the geometric parameters and material toughness levels. The lower-bound deformation limits thus developed follow a linear relationship with respect to the crack-depth ratio for both X- and K-joints. Comparison of the predicated deformation limit against experimental on cracked tubular X- and K- joints demonstrates the conservative nature of the proposed deformation limit. The proposed deformation limit, when extrapolated to a zero crack depth, provides an estimate on the deformation limits for intact X- and K-joints under brace axial loads.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1405100)National Natural Science Foundation of China(Grant No.12074378)Chinese Academy of Sciences(Grants No.YSBR-030,No.JZHKYPT-2021-08,No.XDB33000000).
文摘To realize room temperature ferromagnetic(FM)semiconductors is still a challenge in spintronics.Many antiferromagnetic(AFM)insulators and semiconductors with high Neel temperature TN are obtained in experiments,such as LaFeO_(3),BiFeO_(3),etc.High concentrations of magnetic impurities can be doped into these AFM materials,but AFM state with very tiny net magnetic moments was obtained in experiments because the magnetic impurities were equally doped into the spin up and down sublattices of the AFM materials.Here,we propose that the effective magnetic field provided by a FM substrate could guarantee the spin-dependent doping in AFM materials,where the doped magnetic impurities prefer one sublattice of spins,and the ferrimagnetic(FIM)materials are obtained.To demonstrate this proposal,we study the Mn-doped AFM insulator LaFeO_(3)with FM substrate of Fe metal by the density functional theory(DFT)calculations.
基金This work was supported by grants from the National Natural Science Foundation of China，from National Nonprofit Institute Research Grants
文摘Dear Editor, Triacylglycerols （triglycerides） （TAGs）, as the major storage forms of energy, mainly are stored in adipocytes, myocytes, enterocytes, hepatocytes, and mammary epithelial cells in mammals, oilseeds in plants, and lipid droplets in microorgan- isms （Yen et al., 2008）. Aside from energy storage, TAGs have essential functions in multiple physiological processes. In plants, TAGs are crucial for seed oil accumulation, germina- tion, and seedling development （Zhang et al., 2005, 2009）. Notably, TAGs derived from plants and microorganisms could serve as the feedstock for biofuels production （Deng et al., 2009）. Therefore, understanding of the molecular basis of TAGs bio- synthesis and storage is of considerable economic importance.
基金This work was supported by the National Key Laboratory of CNS/ATM,Bei-jing Key Laboratory for Network-based Cooperative Air Traffic Manage-ment and the State Key Program of National Natural Science of China(No.71731001)。
文摘Unmanned aerial vehicle(UAV)has a rapid development over the last decade.However,an increasing number of severe flight collision events caused by explosive growth of UAV have drawn widespread concern.It is an important issue to investigate safety management approaches of UAVs to ensure safe and efficient operation.In this paper,we present a comprehensive overview of safety management approaches in large,middle and small scales.In large-scale safety management,path-planning problem is a crucial issue to ensure safety and ordered operation of UAVs globally.In middle-scale safety management,it is an important issue to study the conflict detection and resolution methods.And in small-scale safety management,real-time collision avoidance is the last line of ensuring safety.Moreover,a UAV can be regarded as a terminal device connected through communication and information network.Therefore,the enabling technologies,such as sensing,command and control communication,and collaborative decision-making control technology,have been studied in the last.
基金supported in part by the National Key R&D Program of China(Grant No.2018YFA0305800)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB28000000)+5 种基金the National Natural Science Foundation of China(Grant No.11834014)the Innovation Program for Quantum Science and Technology(No.2021ZD0301800)B.G.is supported in part by the National Natural Science Foundation of China(Grant No.12074378)the Chinese Academy of Sciences(Grant No.YSBR-030 and No.Y929013EA2)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB33000000)the Beijing Natural Science Foundation(Grant No.Z190011).
文摘The recently discovered ATi_(3)Bi_(5)(A=Cs,Rb)exhibit intriguing quantum phenomena including superconductivity,electronic nematicity,and abundant topological states.ATi_(3)Bi_(5)present promising platforms for studying kagome superconductivity,band topology,and charge orders in parallel with AV3Sb5.In this work,we comprehensively analyze various properties of ATi_(3)Bi_(5)covering superconductivity under pressure and doping,band topology under pressure,thermal conductivity,heat capacity,electrical resistance,and spin Hall conductivity(SHC)using first-principles calculations.Calculated superconducting transition temperature(Tc)of CsTi_(3)Bi_(5)and RbTi_(3)Bi_(5)at ambient pressure are about 1.85 and 1.92 K.When subject to pressure,Tc of CsTi_(3)Bi_(5)exhibits a special valley and dome shape,which arises from quasi-two-dimensional compression to three-dimensional isotropic compression within the context of an overall decreasing trend.Furthermore,Tc of RbTi_(3)Bi_(5)can be effectively enhanced up to 3.09 K by tuning the kagome van Hove singularities(VHSs)and flat band through doping.Pressures can also induce abundant topological surface states at the Fermi energy(EF)and tune VHSs across EF.Additionally,our transport calculations are in excellent agreement with recent experiments,confirming the absence of charge density wave.Notably,SHC of CsTi_(3)Bi_(5)can reach up to 226h·(e·Ω·cm)^(-1)at EF.Our work provides a timely and detailed analysis of the rich physical properties for ATi_(3)Bi_(5),offering valuable insights for further experimental verifications and investigations in this field.
