Valley Nernst effect is a newly proposed and experimentally confirmed effect,which could be used to design novel thermoelectric devices.We study the valley Nernst effect in(M+N)-layer twisted multilayer graphene syste...Valley Nernst effect is a newly proposed and experimentally confirmed effect,which could be used to design novel thermoelectric devices.We study the valley Nernst effect in(M+N)-layer twisted multilayer graphene systems by a simple low-energy effective model.It is found that the total valley Nernst coefficient(VNC)is three orders of magnitude larger than that in monolayer group-Ⅵdichalcogenides.The total VNC increases with the increase of layer numbers.It is shown that the total VNC exhibits a structure with three peaks as a function of the Fermi energy.We identify that the central peak is always negative stemming from the flat band.Two shoulder peaks are positively induced by the conduction and valence bands,respectively.These predicted features can be tested experimentally.The present work would shed more light on valley caloritronics.展开更多
Background:Anxiety is a common comorbidity associated with chronic obstructive pulmonary disease(COPD),but no well-recognized method can provide effective relief.Liuzijue Qigong(LQG)is a traditional Chinese fitness me...Background:Anxiety is a common comorbidity associated with chronic obstructive pulmonary disease(COPD),but no well-recognized method can provide effective relief.Liuzijue Qigong(LQG)is a traditional Chinese fitness method,based on breath pronunciation.This study aimed to examine the efficacy of LQG to relieve anxiety in COPD patients and to explore the factors that influence anxiety,including whether LQG is effective during the coronavirus disease 2019(COVID-19)outbreak.Methods:We conducted an open-label,randomized,controlled,clinical trial.A total of 60 patients with stable COPD were randomly assigned to two groups.Both groups were given routine medical treatment,and the patients in the pulmonary rehabilitation(PR)group were given an extra intervention in the form of LQG,performed for 30 minutes each day for 12 weeks.Data collection was performed at baseline and 12 weeks(during the COVID-19 epidemic).The primary outcomes were the self-rating anxiety scale(SAS)scores,and the secondary outcomes were relevant information during the epidemic and analyses of the related factors that influenced SAS scores during the COVID-19 outbreak.Results:Compared with baseline,patients in both groups demonstrated varying degrees of improvements in their SAS scores(all P<0.01).An analysis of covariance,adjusted for baseline scores,indicated that the SAS scores improved more dramatically in the PR group than in the control group(F=9.539,P=0.004).During the outbreak,the SAS scores for sleep disorder were higher than all other factors,reaching 1.38±0.67,and the scores for“I can breathe in and out easily”for the PR group were lower than the scores for the control group(Z=−2.108,P=0.035).Significant differences were identified between the two groups for the categories“How much has the outbreak affected your life”,“Do you practice LQG during the epidemic”and“Do you practice other exercises during the epidemic”(all P<0.05).Compared with current reports,LQG had a relatively high adherence rate(80.95%).A multiple linear regression analysis revealed multiple predictors for SAS scores during the outbreak:group(b=−3.907,t=−3.824,P<0.001),COPD assessment test score(b=0.309,t=2.876,P=0.006),SAS score at baseline(b=0.189,t=3.074,P=0.004),and living in a village(b=4.886,t=2.085,P=0.043).Conclusion:LQG could effectively reduce the risks of anxiety among COPD patients,even during the COVID-19 outbreak.For those COPD patients with high COPD assessment test and high baseline SAS scores or who live in villages,we should reinforce the management and intervention of psychological factors during the epidemic.展开更多
Two-dimensional(2D)ferromagnetic and ferroelectric materials attract unprecedented attention due to the spontaneous-symmetry-breaking induced novel properties and multifarious potential applications.Here we systematic...Two-dimensional(2D)ferromagnetic and ferroelectric materials attract unprecedented attention due to the spontaneous-symmetry-breaking induced novel properties and multifarious potential applications.Here we systematically investigate a large family(148)of 2D MGeX3(M=metal elements,X=O/S/Se/Te)by means of the high-throughput first-principles calculations,and focus on their possible ferroic properties including ferromagnetism,ferroelectricity,and ferroelasticity.We discover eight stable 2D ferromagnets including five semiconductors and three half-metals,212D antiferromagnets,and 11 stable 2D ferroelectric semiconductors including two multiferroic materials.Particularly,MnGeSe3 and MnGeTe3 are predicted to be room-temperature 2D ferromagnetic half metals with Tc of 490 and 308 K,respectively.It is probably for the first time that ferroelectricity is uncovered in 2D MGeX3 family,which derives from the spontaneous symmetry breaking induced by unexpected displacements of Ge-Ge atomic pairs,and we also reveal that the electric polarizations are in proportion to the ratio of electronegativity of X and M atoms,and IVB group metal elements are highly favored for 2D ferroelectricity.Magnetic tunnel junction and water-splitting photocatalyst based on 2D ferroic MGeX3 are proposed as examples of wide potential applications.The atlas of ferroicity in 2D MGeX3 materials will spur great interest in experimental studies and would lead to diverse applications.展开更多
Topological insulators(TIs)are considered as ideal platforms for generating large spin Hall conductivity(SHC),however,the bulk carrier problem,which is unavoidable in TIs,hinders their practical applications.Recently,...Topological insulators(TIs)are considered as ideal platforms for generating large spin Hall conductivity(SHC),however,the bulk carrier problem,which is unavoidable in TIs,hinders their practical applications.Recently,topological semimetals(TSMs)have been proposed to achieve large SHC to replace TIs.However,the ideal TSM candidates with large SHC are still lacking.In terms of firstprinciples calculations,we predict that Ta3As family compounds exhibit complex crossing nodal-lines(CNL)properties in absence of the spin-orbit coupling(SOC).However,they transfer to Dirac TSMs under the influence of strong SOC,and present large SHC around Fermi level in particular.Remarkably,the SHC value of Ta_(3)Y(Y=As,Sb,Bi)is around 1500–1700 e/h=eTeΩ·cmT^(-1),which is comparable to noble metal Pt and much larger than TIs,Weyl TSMs,and 4d/5d transition metals.Our work not only suggests a kind of TSM family with interesting Dirac CNL around Fermi level,but also paves the way for searching large intrinsic SHC materials in complex CNL TSM systems.展开更多
基金Project supported in part by the National Key R&D Program of China(Grant No.2018YFA0305800)the National Natural Science Foundation of China(Grant Nos.11974348 and 11834014)+2 种基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDB28000000 and XDB33000000)supported in part by the Training Program of Major Research plan of the National Natural Science Foundation of China(Grant No.92165105)CAS Project for Young Scientists in Basic Research(Grant No.YSBR-057)。
文摘Valley Nernst effect is a newly proposed and experimentally confirmed effect,which could be used to design novel thermoelectric devices.We study the valley Nernst effect in(M+N)-layer twisted multilayer graphene systems by a simple low-energy effective model.It is found that the total valley Nernst coefficient(VNC)is three orders of magnitude larger than that in monolayer group-Ⅵdichalcogenides.The total VNC increases with the increase of layer numbers.It is shown that the total VNC exhibits a structure with three peaks as a function of the Fermi energy.We identify that the central peak is always negative stemming from the flat band.Two shoulder peaks are positively induced by the conduction and valence bands,respectively.These predicted features can be tested experimentally.The present work would shed more light on valley caloritronics.
基金This study was supported by National Natural Science Foundation of China(No.81673900).
文摘Background:Anxiety is a common comorbidity associated with chronic obstructive pulmonary disease(COPD),but no well-recognized method can provide effective relief.Liuzijue Qigong(LQG)is a traditional Chinese fitness method,based on breath pronunciation.This study aimed to examine the efficacy of LQG to relieve anxiety in COPD patients and to explore the factors that influence anxiety,including whether LQG is effective during the coronavirus disease 2019(COVID-19)outbreak.Methods:We conducted an open-label,randomized,controlled,clinical trial.A total of 60 patients with stable COPD were randomly assigned to two groups.Both groups were given routine medical treatment,and the patients in the pulmonary rehabilitation(PR)group were given an extra intervention in the form of LQG,performed for 30 minutes each day for 12 weeks.Data collection was performed at baseline and 12 weeks(during the COVID-19 epidemic).The primary outcomes were the self-rating anxiety scale(SAS)scores,and the secondary outcomes were relevant information during the epidemic and analyses of the related factors that influenced SAS scores during the COVID-19 outbreak.Results:Compared with baseline,patients in both groups demonstrated varying degrees of improvements in their SAS scores(all P<0.01).An analysis of covariance,adjusted for baseline scores,indicated that the SAS scores improved more dramatically in the PR group than in the control group(F=9.539,P=0.004).During the outbreak,the SAS scores for sleep disorder were higher than all other factors,reaching 1.38±0.67,and the scores for“I can breathe in and out easily”for the PR group were lower than the scores for the control group(Z=−2.108,P=0.035).Significant differences were identified between the two groups for the categories“How much has the outbreak affected your life”,“Do you practice LQG during the epidemic”and“Do you practice other exercises during the epidemic”(all P<0.05).Compared with current reports,LQG had a relatively high adherence rate(80.95%).A multiple linear regression analysis revealed multiple predictors for SAS scores during the outbreak:group(b=−3.907,t=−3.824,P<0.001),COPD assessment test score(b=0.309,t=2.876,P=0.006),SAS score at baseline(b=0.189,t=3.074,P=0.004),and living in a village(b=4.886,t=2.085,P=0.043).Conclusion:LQG could effectively reduce the risks of anxiety among COPD patients,even during the COVID-19 outbreak.For those COPD patients with high COPD assessment test and high baseline SAS scores or who live in villages,we should reinforce the management and intervention of psychological factors during the epidemic.
基金This work is supported in part by the National Key R&D Program of China(No.2018YFA0305800)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB28000000)+2 种基金the National Natural Science Foundation of China(No.11834014)the Beijing Municipal Science and Technology Commission(No.Z118100004218001)the fundamental research funds for the central universities,and University of Chinese Academy of Sciences.
文摘Two-dimensional(2D)ferromagnetic and ferroelectric materials attract unprecedented attention due to the spontaneous-symmetry-breaking induced novel properties and multifarious potential applications.Here we systematically investigate a large family(148)of 2D MGeX3(M=metal elements,X=O/S/Se/Te)by means of the high-throughput first-principles calculations,and focus on their possible ferroic properties including ferromagnetism,ferroelectricity,and ferroelasticity.We discover eight stable 2D ferromagnets including five semiconductors and three half-metals,212D antiferromagnets,and 11 stable 2D ferroelectric semiconductors including two multiferroic materials.Particularly,MnGeSe3 and MnGeTe3 are predicted to be room-temperature 2D ferromagnetic half metals with Tc of 490 and 308 K,respectively.It is probably for the first time that ferroelectricity is uncovered in 2D MGeX3 family,which derives from the spontaneous symmetry breaking induced by unexpected displacements of Ge-Ge atomic pairs,and we also reveal that the electric polarizations are in proportion to the ratio of electronegativity of X and M atoms,and IVB group metal elements are highly favored for 2D ferroelectricity.Magnetic tunnel junction and water-splitting photocatalyst based on 2D ferroic MGeX3 are proposed as examples of wide potential applications.The atlas of ferroicity in 2D MGeX3 materials will spur great interest in experimental studies and would lead to diverse applications.
基金The authors thank Bin Huang and Bin Cui for the helpful discussions.We acknowledge the National Key R&D Program of China(2018YFB0407602)Beijing Municipal Science and Technology Project under Grant Z201100004220002+5 种基金the Fundamental Research Funds for the Central Universities and the China Postdoctoral Science Foundation(No.2020M670083,2020M672039)the National Natural Science Foundation of China(Grant Nos.61627813,61571023,11674139,11674317,11974348,11834014,11834005)the Strategic Priority Research Program of CAS(Grant No.XDB28000000 and No.XDB33000000)the National Key Technology Program of China(Grant No.2017ZX01032101)the Special Foundation for Theoretical Physics Research Program of China(No.11947207)for their financial support of this work.Parts of the calculations were performed at Tianhe2-JK at CSRC.
文摘Topological insulators(TIs)are considered as ideal platforms for generating large spin Hall conductivity(SHC),however,the bulk carrier problem,which is unavoidable in TIs,hinders their practical applications.Recently,topological semimetals(TSMs)have been proposed to achieve large SHC to replace TIs.However,the ideal TSM candidates with large SHC are still lacking.In terms of firstprinciples calculations,we predict that Ta3As family compounds exhibit complex crossing nodal-lines(CNL)properties in absence of the spin-orbit coupling(SOC).However,they transfer to Dirac TSMs under the influence of strong SOC,and present large SHC around Fermi level in particular.Remarkably,the SHC value of Ta_(3)Y(Y=As,Sb,Bi)is around 1500–1700 e/h=eTeΩ·cmT^(-1),which is comparable to noble metal Pt and much larger than TIs,Weyl TSMs,and 4d/5d transition metals.Our work not only suggests a kind of TSM family with interesting Dirac CNL around Fermi level,but also paves the way for searching large intrinsic SHC materials in complex CNL TSM systems.
