Developing single-atom catalysts(SACs) for electrochemical devices is a frontier in energy conversion.The comparison of stability,activity and selectivity between various single atoms is one of the main research focus...Developing single-atom catalysts(SACs) for electrochemical devices is a frontier in energy conversion.The comparison of stability,activity and selectivity between various single atoms is one of the main research focuses in SACs.However,the in-depth understanding of the role that the coordination atoms of single atom play in the catalytic process is lacking.Herein,we proposed a graphene-like boroncarbon-nitride(BCN) monolayer as the support of single metal atom.The electrocatalytic nitrogen reduction reaction(eNRR) performances of 3 d,4 d transition metal(TM) atoms embedded in defective BCN were systematically investigated by means of density functional theory(DFT) computations.Our study shows that the TM-to-N and B-to-N π-back bonding can contribute to the activation of N_(2).Importantly,a combined effect is revealed between single TM atom and boron atom on eNRR:TM atom enhances the nitrogen reduction process especially in facilitating the N_(2) adsorption and the NH3 desorption,while boron atom modulates the bonding strength of key intermediates by balancing the charged species.Furthermore,Nb@BN3 possesses the highest electrocata lytic activity with limiting potential of-0.49 V,and exhibits a high selectivity for nitrogen reduction reaction(NRR) to ammonia compared with hydrogen evolution reaction(HER).As such,this work can stimulate a research doorway for designing multi-active sites of the anchored single atoms and the innate atoms of substrate based on the mechanistic insights to guide future eNRR research.展开更多
We use linear entropy of an exact quantum state to study the entanglement between internal electronic states and external motional states for a two-level atom held in an amplitude-modulated and tilted optical lattice....We use linear entropy of an exact quantum state to study the entanglement between internal electronic states and external motional states for a two-level atom held in an amplitude-modulated and tilted optical lattice. Starting from an unentangled initial state associated with the regular ＇island＇ of classical phase space, it is demonstrated that the quantum resonance leads to entanglement generation, the chaotic parameter region results in the increase of the generation speed, and the symmetries of the initial probability distribution determine the final degree of entanglement. The entangled initial states are associated with the classical ＇chaotic sea＇, which do not affect the final entanglement degree for the same initial symmetry. The results may be useful in engineering quantum dynamics for quantum information processing.展开更多
The exciton states of semiconducting carbon nanotubes are calculated by a tight-binding model supplemented by Coulomb interactions under the combined effect of uniaxial strain and magnetic field. It is found that the ...The exciton states of semiconducting carbon nanotubes are calculated by a tight-binding model supplemented by Coulomb interactions under the combined effect of uniaxial strain and magnetic field. It is found that the excitation energies and absorption spectra of zigzag tubes（11,0） and（10,0） show opposite trends with the strain under the action of the magnetic field. For the（11,0） tube, the excitation energy decreases with the increasing uniaxial strain, with a splitting appearing in the absorption spectra. For the（10,0） tube, the variation trend firstly increases and then decreases, with a reversal point appearing in the absorption spectra. More interesting,at the reversal point the intensity of optical absorption is the largest because of the degeneracy of the two bands nearest to the Fermi Level, which is expected to be observed in the future experiment. The similar variation trend is also exhibited in the binding energy for the two kinds of semiconducting tubes.展开更多
Fertilization or atmospheric deposition of nitrogen(N)and phosphorus(P)to terrestrial ecosystems can alter soil N(P)availability and the nature of nutrient limitation for plant growth.Changing the allocation of leaf P...Fertilization or atmospheric deposition of nitrogen(N)and phosphorus(P)to terrestrial ecosystems can alter soil N(P)availability and the nature of nutrient limitation for plant growth.Changing the allocation of leaf P fractions is potentially an adaptive strategy for plants to cope with soil N(P)availability and nutrient-limiting conditions.However,the impact of the interactions between imbalanced anthropogenic N and P inputs on the concentrations and allocation proportions of leaf P fractions in forest woody plants remains elusive.We conducted a metaanalysis of data about the concentrations and allocation proportions of leaf P fractions,specifically associated with individual and combined additions of N and P in evergreen forests,the dominant vegetation type in southern China where the primary productivity is usually considered limited by P.This assessment allowed us to quantitatively evaluate the effects of N and P additions alone and interactively on leaf P allocation and use strategies.Nitrogen addition(exacerbating P limitation)reduced the concentrations of leaf total P and different leaf P fractions.Nitrogen addition reduced the allocation to leaf metabolic P but increased the allocation to other fractions,while P addition showed opposite trends.The simultaneous additions of N and P showed an antagonistic(mutual suppression)effect on the concentrations of leaf P fractions,but an additive(summary)effect on the allocation proportions of leaf P fractions.These results highlight the importance of strategies of leaf P fraction allocation in forest plants under changes in environmental nutrient availability.Importantly,our study identified critical interactions associated with combined N and P inputs that affect leaf P fractions,thus aiding in predicting plant acclimation strategies in the context of intensifying and imbalanced anthropogenic nutrient inputs.展开更多
BACKGROUND The efficacy and safety of proprotein convertase subtilisin/kexin type 9(PCSK-9) inhibitors were confirmed by several clinical trials, but its effectiveness in routine clinical practice in China has not bee...BACKGROUND The efficacy and safety of proprotein convertase subtilisin/kexin type 9(PCSK-9) inhibitors were confirmed by several clinical trials, but its effectiveness in routine clinical practice in China has not been evaluated. This study aims to describe the real world effectiveness of PCSK-9 inhibitors combined with statins compared with statins-based therapy among patients with very high risk of atherosclerotic cardiovascular disease(ASCVD).METHODS This is a multi-center observational study, enrolled patients from 32 hospitals who underwent percutaneous coronary intervention(PCI) from January to June in 2019. There are 453 patients treated with PCSK-9 inhibitors combined with statins in PCSK-9 inhibitor group and 2,610 patients treated with statins-based lipid lowering therapies in statins-based group. The lipid control rate and incidence of major adverse cardiovascular events(MACE) over six months were compared between two groups.A propensity score-matched(PSM) analysis was used to balance two groups on confounding factors. Survival analysis using Kaplan-Meier methods was applied for MACE.RESULTS In a total of 3,063 patients, 89.91% of patients had received moderate or high-intensity statins-based therapy before PCI, but only 9.47% of patients had low-density lipoprotein cholesterol(LDL-C) levels below 1.4 mmol/L at baseline. In the PSM selected patients, LDL-C level was reduced by 42.57% in PCSK-9 inhibitor group and 30.81%(P < 0.001) in statins-based group after six months. The proportion of LDL-C ≤ 1.0 mmol/L increased from 5.29% to 29.26% in PCSK-9 inhibitor group and 0.23% to 6.11% in statins-based group, and the proportion of LDL-C ≤ 1.4 mmol/L increased from 10.36% to 47.69% in PCSK-9 inhibitor group and 2.99% to 18.43% in statins-based group(P < 0.001 for both). There was no significant difference between PCSK-9 inhibitor and statins-based treatment in reducing the risk of MACE(hazard ratio = 2.52, 95% CI: 0.49-12.97, P = 0.250).CONCLUSIONS In the real world, PCSK-9 inhibitors combined with statins could significantly reduce LDL-C levels among patients with very high risk of ASCVD in China. The long-term clinical benefits for patients received PCSK-9 inhibitor to reduce the risk of MACE is still unclear and requires further study.展开更多
Passivating undercoordinated ions is an effective way to reduce the defect densities at the surface and grain boundaries(GBs)of perovskite materials for enhanced photovoltaic performance and stability of perovskite so...Passivating undercoordinated ions is an effective way to reduce the defect densities at the surface and grain boundaries(GBs)of perovskite materials for enhanced photovoltaic performance and stability of perovskite solar cells(PSCs).Here,(BBF)complex is chosen as a multifunctional additive,which contains both C7H9N and BF3 groups working as Lewis base and Lewis acid,respectively,can bond with Pb^(2+)/I^(−) and FA+on the surface and in the GBs in the perovskite film,affording passivation of both cation and anion defects.The synergistic effect of the C7H9N and BF3 complex slows the crystallization during the perovskite film deposition to improve the crystalline quality,which reduces the trap density and the recombination in the perovskite film to suppress nonradiative recombination loss and minimizes moisture permeation to improve the stability of the perovskite material.Meanwhile,such an additive improves the energy-level alignment between the valence band of the perovskite and the highest occupied molecular orbital of the hole-transporting material,Spiro-OMeTAD.Consequently,our work achieves power conversion efficiency of 23.24%,accompanied by enhanced stability under ambient conditions and light illumination and opens a new avenue for improving the performance of PSCs through the use of a multifunctional complex.展开更多
We present a novel four-mirror cavity with two active gains to combine power intracavity and also give a detailed theoretical analysis of the combined gain. By using the effective field method, the four-mirror cavity ...We present a novel four-mirror cavity with two active gains to combine power intracavity and also give a detailed theoretical analysis of the combined gain. By using the effective field method, the four-mirror cavity with two gain media can be regarded as a linear resonator with one effective combined gain （ECG）, and we procure a theoretical model of the ECG and deduce its exact analytical expression. When the two branch gains are close to each other; the combined gain can be reduced to their product; and the simplified presentation of ECG has been demonstrated. The combined output power which directly reflects the small signal ECG of the four-mirror cavity is studied experimentally; and the results are in good agreement with the theoretical ones.展开更多
基金the Fok Ying-Tong Education Foundation for Young Teachers in the Higher Education Institutions of China(grant number 161008)the Basic Research Program of Shenzhen(grant number JCYJ20190809120015163)+4 种基金the Key R&D Program of Hubei province(grant number 2020CFA087)the Fundamental Research Funds for the Central Universities(grant number 2019III-034)the Xiamen University Malaysia Research Fund(grant number XMUMRF/2019-C3/IENG/0013)the Ministry of Higher Education(MOHE)Malaysia under the Fundamental Research Grant Scheme(FRGS)(grant number FRGS/1/2020/TK02/XMU/02/1)the Overseas Expertise Introduction Project(111 project)for Discipline Innovation of China(grant number B18038)。
文摘Developing single-atom catalysts(SACs) for electrochemical devices is a frontier in energy conversion.The comparison of stability,activity and selectivity between various single atoms is one of the main research focuses in SACs.However,the in-depth understanding of the role that the coordination atoms of single atom play in the catalytic process is lacking.Herein,we proposed a graphene-like boroncarbon-nitride(BCN) monolayer as the support of single metal atom.The electrocatalytic nitrogen reduction reaction(eNRR) performances of 3 d,4 d transition metal(TM) atoms embedded in defective BCN were systematically investigated by means of density functional theory(DFT) computations.Our study shows that the TM-to-N and B-to-N π-back bonding can contribute to the activation of N_(2).Importantly,a combined effect is revealed between single TM atom and boron atom on eNRR:TM atom enhances the nitrogen reduction process especially in facilitating the N_(2) adsorption and the NH3 desorption,while boron atom modulates the bonding strength of key intermediates by balancing the charged species.Furthermore,Nb@BN3 possesses the highest electrocata lytic activity with limiting potential of-0.49 V,and exhibits a high selectivity for nitrogen reduction reaction(NRR) to ammonia compared with hydrogen evolution reaction(HER).As such,this work can stimulate a research doorway for designing multi-active sites of the anchored single atoms and the innate atoms of substrate based on the mechanistic insights to guide future eNRR research.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11175064 and 11475060the Construct Program of the National Key Discipline of Chinathe Hunan Provincial Innovation Foundation for Postgraduates under Grant No CX2014B195
文摘We use linear entropy of an exact quantum state to study the entanglement between internal electronic states and external motional states for a two-level atom held in an amplitude-modulated and tilted optical lattice. Starting from an unentangled initial state associated with the regular ＇island＇ of classical phase space, it is demonstrated that the quantum resonance leads to entanglement generation, the chaotic parameter region results in the increase of the generation speed, and the symmetries of the initial probability distribution determine the final degree of entanglement. The entangled initial states are associated with the classical ＇chaotic sea＇, which do not affect the final entanglement degree for the same initial symmetry. The results may be useful in engineering quantum dynamics for quantum information processing.
基金Supported by the National Natural Science Foundation of China under Grant No 11304378the Fundamental Research Funds for the Central Universities under Grant No 2017XKQY093
文摘The exciton states of semiconducting carbon nanotubes are calculated by a tight-binding model supplemented by Coulomb interactions under the combined effect of uniaxial strain and magnetic field. It is found that the excitation energies and absorption spectra of zigzag tubes（11,0） and（10,0） show opposite trends with the strain under the action of the magnetic field. For the（11,0） tube, the excitation energy decreases with the increasing uniaxial strain, with a splitting appearing in the absorption spectra. For the（10,0） tube, the variation trend firstly increases and then decreases, with a reversal point appearing in the absorption spectra. More interesting,at the reversal point the intensity of optical absorption is the largest because of the degeneracy of the two bands nearest to the Fermi Level, which is expected to be observed in the future experiment. The similar variation trend is also exhibited in the binding energy for the two kinds of semiconducting tubes.
基金supported by the National Natural Science Foundation of China(No.41473068)supported by China Postdoctoral Science Foundation(No.2022M722667)。
文摘Fertilization or atmospheric deposition of nitrogen(N)and phosphorus(P)to terrestrial ecosystems can alter soil N(P)availability and the nature of nutrient limitation for plant growth.Changing the allocation of leaf P fractions is potentially an adaptive strategy for plants to cope with soil N(P)availability and nutrient-limiting conditions.However,the impact of the interactions between imbalanced anthropogenic N and P inputs on the concentrations and allocation proportions of leaf P fractions in forest woody plants remains elusive.We conducted a metaanalysis of data about the concentrations and allocation proportions of leaf P fractions,specifically associated with individual and combined additions of N and P in evergreen forests,the dominant vegetation type in southern China where the primary productivity is usually considered limited by P.This assessment allowed us to quantitatively evaluate the effects of N and P additions alone and interactively on leaf P allocation and use strategies.Nitrogen addition(exacerbating P limitation)reduced the concentrations of leaf total P and different leaf P fractions.Nitrogen addition reduced the allocation to leaf metabolic P but increased the allocation to other fractions,while P addition showed opposite trends.The simultaneous additions of N and P showed an antagonistic(mutual suppression)effect on the concentrations of leaf P fractions,but an additive(summary)effect on the allocation proportions of leaf P fractions.These results highlight the importance of strategies of leaf P fraction allocation in forest plants under changes in environmental nutrient availability.Importantly,our study identified critical interactions associated with combined N and P inputs that affect leaf P fractions,thus aiding in predicting plant acclimation strategies in the context of intensifying and imbalanced anthropogenic nutrient inputs.
基金supported by the China Cardiovascular Health Alliance-Advanced Fund (2019CCA-ACCESS-054)the Beijing Lisheng Cardiovascular Health Foundation Pilot Fund Key Projects。
文摘BACKGROUND The efficacy and safety of proprotein convertase subtilisin/kexin type 9(PCSK-9) inhibitors were confirmed by several clinical trials, but its effectiveness in routine clinical practice in China has not been evaluated. This study aims to describe the real world effectiveness of PCSK-9 inhibitors combined with statins compared with statins-based therapy among patients with very high risk of atherosclerotic cardiovascular disease(ASCVD).METHODS This is a multi-center observational study, enrolled patients from 32 hospitals who underwent percutaneous coronary intervention(PCI) from January to June in 2019. There are 453 patients treated with PCSK-9 inhibitors combined with statins in PCSK-9 inhibitor group and 2,610 patients treated with statins-based lipid lowering therapies in statins-based group. The lipid control rate and incidence of major adverse cardiovascular events(MACE) over six months were compared between two groups.A propensity score-matched(PSM) analysis was used to balance two groups on confounding factors. Survival analysis using Kaplan-Meier methods was applied for MACE.RESULTS In a total of 3,063 patients, 89.91% of patients had received moderate or high-intensity statins-based therapy before PCI, but only 9.47% of patients had low-density lipoprotein cholesterol(LDL-C) levels below 1.4 mmol/L at baseline. In the PSM selected patients, LDL-C level was reduced by 42.57% in PCSK-9 inhibitor group and 30.81%(P < 0.001) in statins-based group after six months. The proportion of LDL-C ≤ 1.0 mmol/L increased from 5.29% to 29.26% in PCSK-9 inhibitor group and 0.23% to 6.11% in statins-based group, and the proportion of LDL-C ≤ 1.4 mmol/L increased from 10.36% to 47.69% in PCSK-9 inhibitor group and 2.99% to 18.43% in statins-based group(P < 0.001 for both). There was no significant difference between PCSK-9 inhibitor and statins-based treatment in reducing the risk of MACE(hazard ratio = 2.52, 95% CI: 0.49-12.97, P = 0.250).CONCLUSIONS In the real world, PCSK-9 inhibitors combined with statins could significantly reduce LDL-C levels among patients with very high risk of ASCVD in China. The long-term clinical benefits for patients received PCSK-9 inhibitor to reduce the risk of MACE is still unclear and requires further study.
基金The authors acknowledge support from the National Natural Science Foundation of China(62074095/61704101/91733301)the National Key Research and Development Program of China(2016YFA0202403)+3 种基金the Fundamental Research Funds for the Central Universities GK(201903048)the 111 Project(Grant No.B21005)the Fundament Research Funds for the Central University(2019TS004)DNL Cooperation Fund CAS(DNL180311).
文摘Passivating undercoordinated ions is an effective way to reduce the defect densities at the surface and grain boundaries(GBs)of perovskite materials for enhanced photovoltaic performance and stability of perovskite solar cells(PSCs).Here,(BBF)complex is chosen as a multifunctional additive,which contains both C7H9N and BF3 groups working as Lewis base and Lewis acid,respectively,can bond with Pb^(2+)/I^(−) and FA+on the surface and in the GBs in the perovskite film,affording passivation of both cation and anion defects.The synergistic effect of the C7H9N and BF3 complex slows the crystallization during the perovskite film deposition to improve the crystalline quality,which reduces the trap density and the recombination in the perovskite film to suppress nonradiative recombination loss and minimizes moisture permeation to improve the stability of the perovskite material.Meanwhile,such an additive improves the energy-level alignment between the valence band of the perovskite and the highest occupied molecular orbital of the hole-transporting material,Spiro-OMeTAD.Consequently,our work achieves power conversion efficiency of 23.24%,accompanied by enhanced stability under ambient conditions and light illumination and opens a new avenue for improving the performance of PSCs through the use of a multifunctional complex.
文摘We present a novel four-mirror cavity with two active gains to combine power intracavity and also give a detailed theoretical analysis of the combined gain. By using the effective field method, the four-mirror cavity with two gain media can be regarded as a linear resonator with one effective combined gain （ECG）, and we procure a theoretical model of the ECG and deduce its exact analytical expression. When the two branch gains are close to each other; the combined gain can be reduced to their product; and the simplified presentation of ECG has been demonstrated. The combined output power which directly reflects the small signal ECG of the four-mirror cavity is studied experimentally; and the results are in good agreement with the theoretical ones.
