The development of communication technology will promote the application of Internet of Things,and Beyond 5G will become a new technology promoter.At the same time,Beyond 5G will become one of the important supports f...The development of communication technology will promote the application of Internet of Things,and Beyond 5G will become a new technology promoter.At the same time,Beyond 5G will become one of the important supports for the development of edge computing technology.This paper proposes a communication task allocation algorithm based on deep reinforcement learning for vehicle-to-pedestrian communication scenarios in edge computing.Through trial and error learning of agent,the optimal spectrum and power can be determined for transmission without global information,so as to balance the communication between vehicle-to-pedestrian and vehicle-to-infrastructure.The results show that the agent can effectively improve vehicle-to-infrastructure communication rate as well as meeting the delay constraints on the vehicle-to-pedestrian link.展开更多
Metal halide perovskites have recently emerged as promising candidates for the next generation of X-ray detectors due to their excellent optoelectronic properties.Especially,two-dimensional(2D)perovskites afford many ...Metal halide perovskites have recently emerged as promising candidates for the next generation of X-ray detectors due to their excellent optoelectronic properties.Especially,two-dimensional(2D)perovskites afford many distinct properties,including remarkable structural diversity,high generation energy,and balanced large exciton binding energy.With the advantages of 2D materials and perovskites,it successfully reduces the decomposition and phase transition of perovskite and effectively suppresses ion migration.Meanwhile,the existence of a high hydrophobic spacer can block water molecules,thus making 2D perovskite obtain excellent stability.All of these advantages have attracted much attention in the field of X-ray detection.This review introduces the classification of 2D halide perovskites,summarizes the synthesis technology and performance characteristics of 2D perovskite X-ray direct detector,and briefly discusses the application of 2D perovskite in scintillators.Finally,this review also emphasizes the key challenges faced by 2D perovskite X-ray detectors in practical application and presents our views on its future development.展开更多
Core decompression(CD)with the elimination of osteonecrotic bone is the most common strategy for treating early-stage nontraumatic osteonecrosis of the femoral head(ONFH).Adjuvant treatments are widely used in combina...Core decompression(CD)with the elimination of osteonecrotic bone is the most common strategy for treating early-stage nontraumatic osteonecrosis of the femoral head(ONFH).Adjuvant treatments are widely used in combination with CD as suitable methods of therapy.Existing augmentations have to be fabricated in advance.Here,we report a novel injectable glycerin-modified polycaprolactone(GPCL)that can adapt to the shape of the CD cavity.GPCL shows great flowability at 52.6℃.After solidification,its compressive modulus was 120 kPa at body temperature(37℃).This excellent characteristic enables the polymer to provide mechanical support in vivo.In addition,GPCL acts as a carrier of the therapeutic agent zoledronic acid(ZA),demonstrating sustained release into the CD region.ZA-loaded GPCL was injected into ONFH lesions to treat early-stage nontraumatic cases.Compared to that in the CD group,CD+ZA-loaded GPCL injection preserved bone density and increased the collagen level in the femoral head.At the interface between the GPCL and CD tunnel wall,osteogenesis was significantly promoted.In addition,morphological evaluations revealed that the femoral heads in the CD+ZA-GPCL group exhibited improved pressure resistance.These results suggest a strategy effective to preserve the bone density of the femoral head,thus decreasing the possibility of femoral head collapse.This novel injectable polymer has,therefore,considerable potential in clinical applications.展开更多
Two-dimensional(2D)Dion-Jacobson(D-J)-type cesium lead iodide CsPbI_(3) perform remarkably in terms of stability.However,the complex interactions between spacer and inorganic layers limit its excellent progress in per...Two-dimensional(2D)Dion-Jacobson(D-J)-type cesium lead iodide CsPbI_(3) perform remarkably in terms of stability.However,the complex interactions between spacer and inorganic layers limit its excellent progress in perovskite solar cells(PSCs).Herein,starting from the considerable structural diversity of organic spacers,we engineer 2D CsPbI_(3) with fine-tuning functionalities.Specifically,for the first time we embedded fluorinated aromatic cations in 2D D-J CsPbI_(3),and successfully applied it into construction of high-performance PSCs.Compared with constitutive 1,4-diaminobenzene(PDA),the fluorinated 2-fluorobenzene-1,4-diamine(F-PDA)component greatly expands the dipole moment from 0.59 D to 3.47 D,which reduces the exciton binding energy of the system.A theoretical study shows that the spacer layer and inorganic plane are more enriched with charge accumulation in(F-PDA)Csn±1 Pb_(n)I_(3n+1).The results show that(F-PDA)Csn±1Pb_(n)I_(3n+1) demonstrates more significant charge transfer between organic and inorganic layers than(PDA)Csn±1 Pb_(n)I_(3n+1),and it is confirmed in the femtosecond transient absorption experiment.Moreover,the interactions of the fluorinated spacer with the[PbI_(6)]_(4)-plane effectively manipulate the crystallization quality,and thus the ion migration and defect formation of target 2D CsPbI_(3) are inhibited.As a result,we obtained a record power conversion efficiency(PCE)beyond 15%for 2D D-J(F-PDA)Cs_(3)Pb_(4)I_(13)(n=4)PSCs with significantly improved environmental stability compared with the three-dimensional(3D)counterparts.展开更多
Copper-based metal halides have become important materials in the feld of X-ray and photodetection due to their excellent optical properties,good environmental stability and low toxicity.This review presents the progr...Copper-based metal halides have become important materials in the feld of X-ray and photodetection due to their excellent optical properties,good environmental stability and low toxicity.This review presents the progress of research on crystal structure/morphology,photophysics/optical properties and applications of copper-based metal halides.We also discuss the challenges of copper-based metal halides with a perspective of their future research directions.展开更多
We obtain the optimal integrability for positive solutions of the Euler-Lagrange system of the weighted Hardy-Littlewood-Sobolev inequality in R^n ：{u（x）=1/｜x｜^α｜∫R^n v（y）^q｜y｜^β｜x-y｜^λdy,v（x）=1/｜x...We obtain the optimal integrability for positive solutions of the Euler-Lagrange system of the weighted Hardy-Littlewood-Sobolev inequality in R^n ：{u（x）=1/｜x｜^α｜∫R^n v（y）^q｜y｜^β｜x-y｜^λdy,v（x）=1/｜x｜^β∫R^n u（y）^p｜y｜^α｜x-y｜^λdy.C. Jin and C. Li [Calc. Var. Partial Differential Equations, 2006, 26： 447-457] developed some very interesting method for regularity lifting and obtained the optimal integrability for p, q 〉 1. Here, based on some new observations, we overcome the difficulty there, and derive the optimal integrability for the case of p, q ≥1 and pq ≠1. This integrability plays a key role in estimating the asymptotic behavior of positive solutions when ｜x｜ →0 and when ｜x｜→∞.展开更多
The power conversion efficiency(PCE)of perovskite solar cells(PSCs)has increased rapidly to 25.7%in 2022.There is growing curiosity about whether it will increase further up to the PCE limit.Understanding the fundamen...The power conversion efficiency(PCE)of perovskite solar cells(PSCs)has increased rapidly to 25.7%in 2022.There is growing curiosity about whether it will increase further up to the PCE limit.Understanding the fundamental energy loss mechanism and targeted treatment is the crux to step forward,especially the definite and management of photons in PSCs.Here,we first briefly review the main modes of photon energy loss in PSCs and illustrate the significance of photon recycling.Next,historical research trials to overcome these loss mechanisms in PSCs are highlighted,including the application of anti-reflection coatings,plasmonic strategies,and the adoption of upconversion and downconversion materials.Finally,we make a brief summary and prospect about strategies that can help to improve photon management in the future.展开更多
基金supported by National Natural Science Foundation of China(No.61871283)the Foundation of Pre-Research on Equipment of China(No.61400010304)Major Civil-Military Integration Project in Tianjin,China(No.18ZXJMTG00170).
文摘The development of communication technology will promote the application of Internet of Things,and Beyond 5G will become a new technology promoter.At the same time,Beyond 5G will become one of the important supports for the development of edge computing technology.This paper proposes a communication task allocation algorithm based on deep reinforcement learning for vehicle-to-pedestrian communication scenarios in edge computing.Through trial and error learning of agent,the optimal spectrum and power can be determined for transmission without global information,so as to balance the communication between vehicle-to-pedestrian and vehicle-to-infrastructure.The results show that the agent can effectively improve vehicle-to-infrastructure communication rate as well as meeting the delay constraints on the vehicle-to-pedestrian link.
基金This work was funded by the National Natural Science Foundation of China(22279049 and 12247101)the Fundamental Research Funds for the Central Universities(lzujbky-2021-it31,lzujbky-2021-ct15 and lzujbky-2021-sp69)+1 种基金the calculation work was supported by Supercomputing Center of Lanzhou Universitythe Gansu Province Outstanding Doctoral Student Program(22JR5RA435).
文摘Metal halide perovskites have recently emerged as promising candidates for the next generation of X-ray detectors due to their excellent optoelectronic properties.Especially,two-dimensional(2D)perovskites afford many distinct properties,including remarkable structural diversity,high generation energy,and balanced large exciton binding energy.With the advantages of 2D materials and perovskites,it successfully reduces the decomposition and phase transition of perovskite and effectively suppresses ion migration.Meanwhile,the existence of a high hydrophobic spacer can block water molecules,thus making 2D perovskite obtain excellent stability.All of these advantages have attracted much attention in the field of X-ray detection.This review introduces the classification of 2D halide perovskites,summarizes the synthesis technology and performance characteristics of 2D perovskite X-ray direct detector,and briefly discusses the application of 2D perovskite in scintillators.Finally,this review also emphasizes the key challenges faced by 2D perovskite X-ray detectors in practical application and presents our views on its future development.
基金supported by the National Natural Science Foundation of China(NSFC:81672173,82072448)the Key Research Development Program of Shaanxi Province(2018ZDCXL-SF-28-7)。
文摘Core decompression(CD)with the elimination of osteonecrotic bone is the most common strategy for treating early-stage nontraumatic osteonecrosis of the femoral head(ONFH).Adjuvant treatments are widely used in combination with CD as suitable methods of therapy.Existing augmentations have to be fabricated in advance.Here,we report a novel injectable glycerin-modified polycaprolactone(GPCL)that can adapt to the shape of the CD cavity.GPCL shows great flowability at 52.6℃.After solidification,its compressive modulus was 120 kPa at body temperature(37℃).This excellent characteristic enables the polymer to provide mechanical support in vivo.In addition,GPCL acts as a carrier of the therapeutic agent zoledronic acid(ZA),demonstrating sustained release into the CD region.ZA-loaded GPCL was injected into ONFH lesions to treat early-stage nontraumatic cases.Compared to that in the CD group,CD+ZA-loaded GPCL injection preserved bone density and increased the collagen level in the femoral head.At the interface between the GPCL and CD tunnel wall,osteogenesis was significantly promoted.In addition,morphological evaluations revealed that the femoral heads in the CD+ZA-GPCL group exhibited improved pressure resistance.These results suggest a strategy effective to preserve the bone density of the femoral head,thus decreasing the possibility of femoral head collapse.This novel injectable polymer has,therefore,considerable potential in clinical applications.
基金supported by the National Natural Science Foundation of China(52073131,51902148,and 12047501)the Fundamental Research Funds for the Central Universities(lzujbky-2021-it31,lzujbky-2021-59,lzujbky-2021-ct15,lzujbky2021-ct01,and lzujbky-2021-sp69)supported by Supercomputing Center of Lanzhou University。
文摘Two-dimensional(2D)Dion-Jacobson(D-J)-type cesium lead iodide CsPbI_(3) perform remarkably in terms of stability.However,the complex interactions between spacer and inorganic layers limit its excellent progress in perovskite solar cells(PSCs).Herein,starting from the considerable structural diversity of organic spacers,we engineer 2D CsPbI_(3) with fine-tuning functionalities.Specifically,for the first time we embedded fluorinated aromatic cations in 2D D-J CsPbI_(3),and successfully applied it into construction of high-performance PSCs.Compared with constitutive 1,4-diaminobenzene(PDA),the fluorinated 2-fluorobenzene-1,4-diamine(F-PDA)component greatly expands the dipole moment from 0.59 D to 3.47 D,which reduces the exciton binding energy of the system.A theoretical study shows that the spacer layer and inorganic plane are more enriched with charge accumulation in(F-PDA)Csn±1 Pb_(n)I_(3n+1).The results show that(F-PDA)Csn±1Pb_(n)I_(3n+1) demonstrates more significant charge transfer between organic and inorganic layers than(PDA)Csn±1 Pb_(n)I_(3n+1),and it is confirmed in the femtosecond transient absorption experiment.Moreover,the interactions of the fluorinated spacer with the[PbI_(6)]_(4)-plane effectively manipulate the crystallization quality,and thus the ion migration and defect formation of target 2D CsPbI_(3) are inhibited.As a result,we obtained a record power conversion efficiency(PCE)beyond 15%for 2D D-J(F-PDA)Cs_(3)Pb_(4)I_(13)(n=4)PSCs with significantly improved environmental stability compared with the three-dimensional(3D)counterparts.
基金funded by the National Natural Science Foundation of China(Grant Nos.22279049 and 52073131)the Fundamental Research Funds for the Central Universities(Nos.lzujbky-2021-ct15 and lzujbky-2021-sp69).
文摘Copper-based metal halides have become important materials in the feld of X-ray and photodetection due to their excellent optical properties,good environmental stability and low toxicity.This review presents the progress of research on crystal structure/morphology,photophysics/optical properties and applications of copper-based metal halides.We also discuss the challenges of copper-based metal halides with a perspective of their future research directions.
基金Acknowledgements The authors wish to express their appreciations to the anonymous referees. Their suggestions have greatly improved this paper. They are also grateful to Prof. Congming Li for many fruitful discussion. The first author was supported by the National Natural Science Foundation of China （Grant No. 11171158）, the Natural Science Foundation of Jiangsu （No. BK2012846）, and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry.
文摘We obtain the optimal integrability for positive solutions of the Euler-Lagrange system of the weighted Hardy-Littlewood-Sobolev inequality in R^n ：{u（x）=1/｜x｜^α｜∫R^n v（y）^q｜y｜^β｜x-y｜^λdy,v（x）=1/｜x｜^β∫R^n u（y）^p｜y｜^α｜x-y｜^λdy.C. Jin and C. Li [Calc. Var. Partial Differential Equations, 2006, 26： 447-457] developed some very interesting method for regularity lifting and obtained the optimal integrability for p, q 〉 1. Here, based on some new observations, we overcome the difficulty there, and derive the optimal integrability for the case of p, q ≥1 and pq ≠1. This integrability plays a key role in estimating the asymptotic behavior of positive solutions when ｜x｜ →0 and when ｜x｜→∞.
基金funded by the National Natural Science Foundation of China(52073131)the Fundamental Research Funds for the Central Universities(lzujbky-2021-ct15).
文摘The power conversion efficiency(PCE)of perovskite solar cells(PSCs)has increased rapidly to 25.7%in 2022.There is growing curiosity about whether it will increase further up to the PCE limit.Understanding the fundamental energy loss mechanism and targeted treatment is the crux to step forward,especially the definite and management of photons in PSCs.Here,we first briefly review the main modes of photon energy loss in PSCs and illustrate the significance of photon recycling.Next,historical research trials to overcome these loss mechanisms in PSCs are highlighted,including the application of anti-reflection coatings,plasmonic strategies,and the adoption of upconversion and downconversion materials.Finally,we make a brief summary and prospect about strategies that can help to improve photon management in the future.
