Two-dimensional van der Waals(2D vdW)magnets have attracted great attention recently and possess the unprecedented advantages of incorporating high-quality vdW heterostructures and homostructures into spintronic devic...Two-dimensional van der Waals(2D vdW)magnets have attracted great attention recently and possess the unprecedented advantages of incorporating high-quality vdW heterostructures and homostructures into spintronic devices,and exploring various physical phenomena or technologies.Among them,Fe_(5)GeTe_(2)(F5GT)has ferromagnetic order close to room temperature,however the magnetic properties near its intrinsic transitions and F5GT-based 2D devices remain mostly unexplored.Here,we systematically demonstrate the peculiar magnetic properties of Fe_(5)GeTe_(2)nanoflakes near its intrinsic transition temperature(Tp)which is far lower than its Curie temperature(TC)of~265 K,and firstly discover anomalous magnetoresistance effect in F5GT homo-junctions by magneto-transport measurements.The strongest anomalous Hall effect occurs around Tp which is located in a temperature range from 130 to 160 K for the F5GT nanoflakes with different thicknesses.Furthermore,negative magnetoresistance(N-MR)and butterfly-shaped magnetoresistance(B-MR)are observed in F5GT homo-junction devices,and they appeared only in an intermediate temperature range from 110 to 160 K,noticeably showing the maxima near the T_(p)rather than the lowest temperature.Our experimental results clearly reveal the significant influence of intrinsic transitions on magnetic properties of F5GT and magnetoresistance effect in F5GT homo-junction devices,which imply a new strategy to achieve highperformance 2D spintronic devices by tuning intrinsic magnetic or structural transitions in 2D vdW magnets.展开更多
lIn response to the severe acute respiratory syndrome coronavirus-2(SARS-CoV-2)pandemic,over 200 vaccine candidates againstcoronavirus disease 2019(COVID-2019)are under development and currently moving forward at an u...lIn response to the severe acute respiratory syndrome coronavirus-2(SARS-CoV-2)pandemic,over 200 vaccine candidates againstcoronavirus disease 2019(COVID-2019)are under development and currently moving forward at an unparalleled speed.Theavailability of surrogate endpoints would help to avoid large-scale filed efficacy trials and facilitate the approval of vaccine candidates,which is crucial to control COVID-19 pandemic.Several phase 3 efficacy trials of COVID-19 vaccine candidates are underway,which provide opportunities for the determination of COVID-19 correlates of protection.In this paper,we review currentknowledge for existence of COVD-19 correlates of protection,methods for assessment of immune correlates of protection andissues related to COVID-19 correlates of protection.展开更多
In this work,we consider employing the NOMA(Non-Orthogonal Multiple Access)technique in downlink VLC(Visible Light Communication)for performance enhancement.In particular,focusing on a typical NOMA scenario with two u...In this work,we consider employing the NOMA(Non-Orthogonal Multiple Access)technique in downlink VLC(Visible Light Communication)for performance enhancement.In particular,focusing on a typical NOMA scenario with two users,we optimize the power allocation strategies under both sum-rate maximization and max-min fairness criteria,where practical optical power and QoS(Quality of Service)constraints are included.As our main contribution,we achieve optimal power allocation solutions in semi-closed forms via mathematical analysis,which,to the best of our knowledge,have not been reported in literature.Simulation results demonstrate that NOMA can provide remarkable performance gains over OMA(Orthogonal Multiple Access)in the context of VLC downlinks.展开更多
基金This work was financially supported by the National Key Research and Development Program of China(No.2022YFA1204004)the National Natural Science Foundation of China(Nos.52071026,52130103,51971026,and 52201288)+3 种基金the ISF-NSFC Joint Research Program(No.51961145305)the Beijing Natural Science Foundation Key Program(No.Z190007)the open research fund of Songshan Lake Materials Laboratory(No.2022SLABFN18)the Fundamental Research Funds for the Central Universities(No.06500140).
文摘Two-dimensional van der Waals(2D vdW)magnets have attracted great attention recently and possess the unprecedented advantages of incorporating high-quality vdW heterostructures and homostructures into spintronic devices,and exploring various physical phenomena or technologies.Among them,Fe_(5)GeTe_(2)(F5GT)has ferromagnetic order close to room temperature,however the magnetic properties near its intrinsic transitions and F5GT-based 2D devices remain mostly unexplored.Here,we systematically demonstrate the peculiar magnetic properties of Fe_(5)GeTe_(2)nanoflakes near its intrinsic transition temperature(Tp)which is far lower than its Curie temperature(TC)of~265 K,and firstly discover anomalous magnetoresistance effect in F5GT homo-junctions by magneto-transport measurements.The strongest anomalous Hall effect occurs around Tp which is located in a temperature range from 130 to 160 K for the F5GT nanoflakes with different thicknesses.Furthermore,negative magnetoresistance(N-MR)and butterfly-shaped magnetoresistance(B-MR)are observed in F5GT homo-junction devices,and they appeared only in an intermediate temperature range from 110 to 160 K,noticeably showing the maxima near the T_(p)rather than the lowest temperature.Our experimental results clearly reveal the significant influence of intrinsic transitions on magnetic properties of F5GT and magnetoresistance effect in F5GT homo-junction devices,which imply a new strategy to achieve highperformance 2D spintronic devices by tuning intrinsic magnetic or structural transitions in 2D vdW magnets.
基金supported by the National Key Research and Development Program of China(2021YFB3501202 and 2019YFB2005800)the Science Center of the National Science Foundation of China(52088101)+1 种基金the National Natural Science Foundation of China(51871019,52171170,52130103,51961145305,and 51971026)the 111 Project(B170003)。
基金supported by Jiangsu Province Special Funds for Key Research&Developm ent(2060499).
文摘lIn response to the severe acute respiratory syndrome coronavirus-2(SARS-CoV-2)pandemic,over 200 vaccine candidates againstcoronavirus disease 2019(COVID-2019)are under development and currently moving forward at an unparalleled speed.Theavailability of surrogate endpoints would help to avoid large-scale filed efficacy trials and facilitate the approval of vaccine candidates,which is crucial to control COVID-19 pandemic.Several phase 3 efficacy trials of COVID-19 vaccine candidates are underway,which provide opportunities for the determination of COVID-19 correlates of protection.In this paper,we review currentknowledge for existence of COVD-19 correlates of protection,methods for assessment of immune correlates of protection andissues related to COVID-19 correlates of protection.
基金s supported by the National Basic Research Program of China(973 Program)(No.2013CB329204)the National Natural Science Foundation of China(Nos.61501110,61471114,61461136003,61571118,and 61521061)+1 种基金the Natural Science Foundation of Jiangsu Province(No.BK20150635)the Fundamental Research Funds for Central Universities(No.2242016K41080).
文摘In this work,we consider employing the NOMA(Non-Orthogonal Multiple Access)technique in downlink VLC(Visible Light Communication)for performance enhancement.In particular,focusing on a typical NOMA scenario with two users,we optimize the power allocation strategies under both sum-rate maximization and max-min fairness criteria,where practical optical power and QoS(Quality of Service)constraints are included.As our main contribution,we achieve optimal power allocation solutions in semi-closed forms via mathematical analysis,which,to the best of our knowledge,have not been reported in literature.Simulation results demonstrate that NOMA can provide remarkable performance gains over OMA(Orthogonal Multiple Access)in the context of VLC downlinks.
