Dear Editor,Hepatitis B virus(HBV)is a small,enveloped DNA virus and a member of the Hepadnaviridae family(Zhao et al.,2020).It is a major human pathogen causing chronic liver disease,leading to significant morbidity ...Dear Editor,Hepatitis B virus(HBV)is a small,enveloped DNA virus and a member of the Hepadnaviridae family(Zhao et al.,2020).It is a major human pathogen causing chronic liver disease,leading to significant morbidity and mortality worldwide(Xia and Liang,2019).According to the World Health Organization(WHO),an estimated 296 million people live with chronic HBV infection,contributing to around 820,000 deaths annually due to complications such as liver cirrhosis and hepatocellular carcinoma(HCC)(Easterbrook et al.,2021).展开更多
The Southern Ocean is a critical component in the Earth system by dominating the global heat and anthropogenic carbon uptake and supplying heat to melt the largest ice sheet.Variability and changes in the water masses...The Southern Ocean is a critical component in the Earth system by dominating the global heat and anthropogenic carbon uptake and supplying heat to melt the largest ice sheet.Variability and changes in the water masses of the Southern Ocean are thus important to the global energy and water cycles,carbon cycling,and sea-level change.In this article,we review the recent progress on understanding the variability and changes in the four major water masses in the Southern Ocean,including Subantarctic Mode Water,Antarctic Intermediate Water,Circumpolar Deep Water and Antarctic Bottom Water.Subantarctic Mode Water and Antarctic Intermediate Water show statistically significant strong circumpolar shoaling,warming,and density reductions since 1970s,indicating that signals of global warming have entered the interior ocean.Meanwhile,strong regional variability of Subantarctic Mode Water and Antarctic Intermediate Water responding to surface buoyancy forcing and westerly winds is attracting more attention.Circumpolar Deep Water is an important modulator of heat content and nutrient concentrations on continental shelves around Antarctica and has made significant contributions to the basal melting of Antarctic ice shelves.Since the late 1950s,a long-term freshening trend in Antarctic Bottom Water in the Ross Sea and its downstream region has been observed and is mainly attributed to the accelerated basal melting of ice shelves in West Antarctica.The shrinking of Antarctic Bottom Water in the Weddell Sea during 1992–2020 has also been revealed and is attributed to reduced sea ice production over the southern Weddell continental shelf related to the Interdecadal Pacific Oscillation and the variability in the Amundsen Sea Low.Though significant advances have been achieved,there is an urgent need to enhance and improve both observations and model performances for better understandings and projections of the formation,transformation,and transport of the water masses in the Southern Ocean.展开更多
As the development of new power systems progresses,the inherent inertia of power systems continues to diminish.Centralized frequency regulation,which relies on rapid communication and real-time control,can enable inve...As the development of new power systems progresses,the inherent inertia of power systems continues to diminish.Centralized frequency regulation,which relies on rapid communication and real-time control,can enable inverter-based thermostatically controlled load(ITCL)clusters to provide virtual inertia support to the power grid.However,ITCL clusters exhibit significant discrete response characteristics,which precludes the direct integration of load-side inertia support into the synchronous unit side.To address this issue,this paper elaborates on the existing technical framework and analyzes the underlying causes of the problem.It proposes a timestamp allocation mechanism for ITCL cluster control instructions,ensuring that many ITCL terminals can be triggered at staggered times,thereby allowing the load cluster power to adhere to the inertia analog control law at any moment.Building on this foundation,the paper further examines the impact of the inertia response delay of ITCL clusters,which is based on centralized frequency regulation,on the stability of the power system.A design scheme for inertia analog control parameters is proposed,taking into account dual constraints,frequency stability and load cluster regulation capacity.Finally,the feasibility and applicability of the proposed mechanism and parameter design scheme are investigated through simulations conducted via MATLAB/Simulink.展开更多
This work proposes an online collaborative hunting strategy for multi-robot systems based on obstacle-avoiding Voronoi cells in a complex dynamic environment. This involves firstly designing the construction method us...This work proposes an online collaborative hunting strategy for multi-robot systems based on obstacle-avoiding Voronoi cells in a complex dynamic environment. This involves firstly designing the construction method using a support vector machine(SVM) based on the definition of buffered Voronoi cells(BVCs). Based on the safe collision-free region of the robots, the boundary weights between the robots and the obstacles are dynamically updated such that the robots are tangent to the buffered Voronoi safety areas without intersecting with the obstacles. Then, the robots are controlled to move within their own buffered Voronoi safety area to achieve collision-avoidance with other robots and obstacles. The next step involves proposing a hunting method that optimizes collaboration between the pursuers and evaders. Some hunting points are generated and distributed evenly around a circle. Next, the pursuers are assigned to match the optimal points based on the Hungarian algorithm.Then, a hunting controller is designed to improve the containment capability and minimize containment time based on collision risk. Finally, simulation results have demonstrated that the proposed cooperative hunting method is more competitive in terms of time and travel distance.展开更多
Conductive polymer composites(CPCs)are widely used in the field of organic electronics as the material basis of high-performance devices,due to their obvious advantages including electrical conductivity,lightness,proc...Conductive polymer composites(CPCs)are widely used in the field of organic electronics as the material basis of high-performance devices,due to their obvious advantages including electrical conductivity,lightness,processability and so on.Research on CPCs has focused on the enhancement of their electrical features and the exploration of their application prospects from conventional fields to heated emerging areas like flexible,stretchable,wearable,biological and biomedical electronics,where their mechanical properties are quite critical to determine their practical device performances.Also,a main challenge to ensure their safety and reliability is on the synergistic enhancement of their electrical behavior and mechanical properties.Herein,we systematically review the research progress of CPCs with different conductive fillers(metals and their oxides,carbon-based materials,intrinsically conductive polymers,MXenes,etc.)relying on rich material forms(hydrogel,aerogel,fiber,film,elastomer,etc.)in terms of mechanical property regulation strategies,mainly relying on optimized composite material systems and processing techniques.A summary and prospective overview of current issues and future developments in this field also has been presented.展开更多
Antarctic coastal polynyas are biological hotspots in the Southern Ocean that support the abundance of hightrophic-level predators and are important for carbon cycling in the high-latitude oceans.In this study,we exam...Antarctic coastal polynyas are biological hotspots in the Southern Ocean that support the abundance of hightrophic-level predators and are important for carbon cycling in the high-latitude oceans.In this study,we examined the interannual variation of summertime phytoplankton biomass in the Marguerite Bay polynya(MBP)in the western Antarctic Peninsula area,and linked such variability to the Southern Annular Mode(SAM)that dominated the southern hemisphere extratropical climate variability.Combining satellite data,atmosphere reanalysis products and numerical simulations,we found that the interannual variation of summer chlorophyll-a(Chl-a)concentration in the MBP is significantly and negatively correlated with the spring SAM index,and weakly correlated with the summer SAM index.The negative relation between summer Chl-a and spring SAM is due to weaker spring vertical mixing under a more positive SAM condition,which would inhibit the supply of iron from deep layers into the surface euphotic layer.The negative relation between spring mixing and spring SAM results from greater precipitation rate over the MBP region in positive SAM phase,which leads to lower salinity in the ocean surface layer.The coupled physical-biological mechanisms between SAM and phytoplankton biomass revealed in this study is important for us to predict the future variations of phytoplankton biomasses in Antarctic polynyas under climate change.展开更多
In this paper, we investigate the downlink performance of cell-free massive multi-input multi-output non-orthogonal multiple access(CF-m MIMO-NOMA) system with conjugate beamforming precoder and compare against the or...In this paper, we investigate the downlink performance of cell-free massive multi-input multi-output non-orthogonal multiple access(CF-m MIMO-NOMA) system with conjugate beamforming precoder and compare against the orthogonal multiple access(OMA) counterpart. A novel achievable closed-form spectral efficiency(SE) expression is derived, which characterizes the effects of the channel estimation error, pilot contamination, imperfect successive interference cancellation(SIC) operation, and power optimization technique. Then, motivated by the closedform result, a sum-SE maximization algorithm with the sequential convex approximation(SCA) is proposed, subject to each AP power constraint and SIC power constraint. Numerical experiments indicate that the proposed sum-SE maximization algorithms have a fast converge rate, within about five iterations. In addition, compared with the full power control(FPC) scheme, our algorithms can significantly improve the achievable sum-SE. Moreover, NOMA outperforms OMA in many respects in the presence of the proposed algorithms.展开更多
In this paper,biocarbon was prepared from corn husks as anode materials for potassium ion batteries at temperatures ranging from 700 to 1600℃.The prepared biocarbon materials have amorphous phase structure and posses...In this paper,biocarbon was prepared from corn husks as anode materials for potassium ion batteries at temperatures ranging from 700 to 1600℃.The prepared biocarbon materials have amorphous phase structure and possess larger interlayer spacing than graphite.The biocarbon exhibits enhanced graphitic degree and decreased amounts of surface defects,while the carbonization temperature gradually increases.The obtained potassium ion battery electrode at 1300℃ acquired high reversible capacity up to 216.6 mAh·g^(-1) at 0.1 A·g^(-1) after 100 cycles, and retained 128.6 mAh·g^(-1) at 1 A·g^(-1) even after500 cycles.The results indicate that the samples prepared at 1300℃ have better electrochemical performance than other samples prepared at different temperatures,which was attributed to the decisive influence of microstructure on surface-induced and intercalating potassium storage.展开更多
基金supported by the National Key Research and Development Program of China(No.2023YFC2308500)the Fundamental Research Funds for the Central Universities(project no.2042024kf0026),the Open Grant from the Pingyuan Laboratory(2023PY-OP-0101)+3 种基金the National Natural Science Foundation of China(project no.81971936,32100125 and 32300131)Hubei Province's Outstanding Medical Academic Leader Program,East Lake Hi-tech Development Zone Unveiling and Commanding Project(No.2023KJB219)Science and Technology Talent Service Enterprise Project(No.2024DJC064)Basic and Clinical Medical Research Joint Fund of Zhongnan Hospital,Wuhan University.
文摘Dear Editor,Hepatitis B virus(HBV)is a small,enveloped DNA virus and a member of the Hepadnaviridae family(Zhao et al.,2020).It is a major human pathogen causing chronic liver disease,leading to significant morbidity and mortality worldwide(Xia and Liang,2019).According to the World Health Organization(WHO),an estimated 296 million people live with chronic HBV infection,contributing to around 820,000 deaths annually due to complications such as liver cirrhosis and hepatocellular carcinoma(HCC)(Easterbrook et al.,2021).
基金The Independent Research Foundation of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)under contract Nos SML2023SP201 and SML2021SP306the Natural Science Foundation of Guangdong Province of China under contract No.2024A1515012717+5 种基金the Initial Research Foundation of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)under contract Nos 313021004,313022009,and 313022001the National Natural Science Foundation of China under contract No.41706225the National Key R&D Program of China under contract No.2018YFA0605701the Impact and Response of Antarctic Seas to Climate Change under contract No.IRASCC 1-02-01Bthe Shenlan Program funded by Shanghai Jiao Tong University under contract No.SL2020MS021the fund from Shanghai Frontiers Science Center of Polar Research.
文摘The Southern Ocean is a critical component in the Earth system by dominating the global heat and anthropogenic carbon uptake and supplying heat to melt the largest ice sheet.Variability and changes in the water masses of the Southern Ocean are thus important to the global energy and water cycles,carbon cycling,and sea-level change.In this article,we review the recent progress on understanding the variability and changes in the four major water masses in the Southern Ocean,including Subantarctic Mode Water,Antarctic Intermediate Water,Circumpolar Deep Water and Antarctic Bottom Water.Subantarctic Mode Water and Antarctic Intermediate Water show statistically significant strong circumpolar shoaling,warming,and density reductions since 1970s,indicating that signals of global warming have entered the interior ocean.Meanwhile,strong regional variability of Subantarctic Mode Water and Antarctic Intermediate Water responding to surface buoyancy forcing and westerly winds is attracting more attention.Circumpolar Deep Water is an important modulator of heat content and nutrient concentrations on continental shelves around Antarctica and has made significant contributions to the basal melting of Antarctic ice shelves.Since the late 1950s,a long-term freshening trend in Antarctic Bottom Water in the Ross Sea and its downstream region has been observed and is mainly attributed to the accelerated basal melting of ice shelves in West Antarctica.The shrinking of Antarctic Bottom Water in the Weddell Sea during 1992–2020 has also been revealed and is attributed to reduced sea ice production over the southern Weddell continental shelf related to the Interdecadal Pacific Oscillation and the variability in the Amundsen Sea Low.Though significant advances have been achieved,there is an urgent need to enhance and improve both observations and model performances for better understandings and projections of the formation,transformation,and transport of the water masses in the Southern Ocean.
基金supported by the Key Scientific and Technological Projects(2024KJGG27)of Tianfu Yongxing Laboratorythe Experimental Platform Open Innovation Funding(209042025003)of Sichuan Energy Internet Research Institute,Tsinghua University.
文摘As the development of new power systems progresses,the inherent inertia of power systems continues to diminish.Centralized frequency regulation,which relies on rapid communication and real-time control,can enable inverter-based thermostatically controlled load(ITCL)clusters to provide virtual inertia support to the power grid.However,ITCL clusters exhibit significant discrete response characteristics,which precludes the direct integration of load-side inertia support into the synchronous unit side.To address this issue,this paper elaborates on the existing technical framework and analyzes the underlying causes of the problem.It proposes a timestamp allocation mechanism for ITCL cluster control instructions,ensuring that many ITCL terminals can be triggered at staggered times,thereby allowing the load cluster power to adhere to the inertia analog control law at any moment.Building on this foundation,the paper further examines the impact of the inertia response delay of ITCL clusters,which is based on centralized frequency regulation,on the stability of the power system.A design scheme for inertia analog control parameters is proposed,taking into account dual constraints,frequency stability and load cluster regulation capacity.Finally,the feasibility and applicability of the proposed mechanism and parameter design scheme are investigated through simulations conducted via MATLAB/Simulink.
基金supported by the National Natural Science Foundation of China (62273007,61973023)Project of Cultivation for Young Top-motch Talents of Beijing Municipal Institutions (BPHR202203032)。
文摘This work proposes an online collaborative hunting strategy for multi-robot systems based on obstacle-avoiding Voronoi cells in a complex dynamic environment. This involves firstly designing the construction method using a support vector machine(SVM) based on the definition of buffered Voronoi cells(BVCs). Based on the safe collision-free region of the robots, the boundary weights between the robots and the obstacles are dynamically updated such that the robots are tangent to the buffered Voronoi safety areas without intersecting with the obstacles. Then, the robots are controlled to move within their own buffered Voronoi safety area to achieve collision-avoidance with other robots and obstacles. The next step involves proposing a hunting method that optimizes collaboration between the pursuers and evaders. Some hunting points are generated and distributed evenly around a circle. Next, the pursuers are assigned to match the optimal points based on the Hungarian algorithm.Then, a hunting controller is designed to improve the containment capability and minimize containment time based on collision risk. Finally, simulation results have demonstrated that the proposed cooperative hunting method is more competitive in terms of time and travel distance.
基金This study was jointly funded by the National Key R&D Program of China[grant number 2022YFC3004103]the National Natural Foundation of China[grant number 42275003]+2 种基金the Beijing Science and Technology Program[grant number Z221100005222012]the Beijing Meteorological Service Science and Technology Program[grant number BMBKJ202302004]the China Meteorological Administration Youth Innovation Team[grant number CMA2023QN10].
基金This work was financially supported by the Academic Development Project of TongXin Funds(No.2024161804).
文摘Conductive polymer composites(CPCs)are widely used in the field of organic electronics as the material basis of high-performance devices,due to their obvious advantages including electrical conductivity,lightness,processability and so on.Research on CPCs has focused on the enhancement of their electrical features and the exploration of their application prospects from conventional fields to heated emerging areas like flexible,stretchable,wearable,biological and biomedical electronics,where their mechanical properties are quite critical to determine their practical device performances.Also,a main challenge to ensure their safety and reliability is on the synergistic enhancement of their electrical behavior and mechanical properties.Herein,we systematically review the research progress of CPCs with different conductive fillers(metals and their oxides,carbon-based materials,intrinsically conductive polymers,MXenes,etc.)relying on rich material forms(hydrogel,aerogel,fiber,film,elastomer,etc.)in terms of mechanical property regulation strategies,mainly relying on optimized composite material systems and processing techniques.A summary and prospective overview of current issues and future developments in this field also has been presented.
基金The Key Research&Development Program of the Ministry of Science and Technology of China under contract No.2022YFC2807601the National Natural Science Foundation of China under contract Nos 41941008 and 41876221+3 种基金the Fund of Shanghai Science and Technology Committee under contract Nos 20230711100 and 21QA1404300the Impact and Response of Antarctic Seas to Climate Change funded by the Chinese Arctic and Antarctic Administration under contract No.IRASCC 1-02-01Bthe National Key Research and Development Program of China under contract No.2019YFC1509102the Shanghai Pilot Program for Basic Research—Shanghai Jiao Tong University under contract No.21TQ1400201。
文摘Antarctic coastal polynyas are biological hotspots in the Southern Ocean that support the abundance of hightrophic-level predators and are important for carbon cycling in the high-latitude oceans.In this study,we examined the interannual variation of summertime phytoplankton biomass in the Marguerite Bay polynya(MBP)in the western Antarctic Peninsula area,and linked such variability to the Southern Annular Mode(SAM)that dominated the southern hemisphere extratropical climate variability.Combining satellite data,atmosphere reanalysis products and numerical simulations,we found that the interannual variation of summer chlorophyll-a(Chl-a)concentration in the MBP is significantly and negatively correlated with the spring SAM index,and weakly correlated with the summer SAM index.The negative relation between summer Chl-a and spring SAM is due to weaker spring vertical mixing under a more positive SAM condition,which would inhibit the supply of iron from deep layers into the surface euphotic layer.The negative relation between spring mixing and spring SAM results from greater precipitation rate over the MBP region in positive SAM phase,which leads to lower salinity in the ocean surface layer.The coupled physical-biological mechanisms between SAM and phytoplankton biomass revealed in this study is important for us to predict the future variations of phytoplankton biomasses in Antarctic polynyas under climate change.
基金supported in part by the National Key Research and Development Program of China under Grant 2018YFC1314903the National Natural Science Foundation of China under Grants 61861039,61372124,and 61427801+1 种基金the Science and Technology Project Foundation of Gansu Province under Grant 18YF1GA060the Postgraduate Research&Practice Innovation Program of Jiangsu Province under Grant SJKY19_0740 and KYCX20_0709。
文摘In this paper, we investigate the downlink performance of cell-free massive multi-input multi-output non-orthogonal multiple access(CF-m MIMO-NOMA) system with conjugate beamforming precoder and compare against the orthogonal multiple access(OMA) counterpart. A novel achievable closed-form spectral efficiency(SE) expression is derived, which characterizes the effects of the channel estimation error, pilot contamination, imperfect successive interference cancellation(SIC) operation, and power optimization technique. Then, motivated by the closedform result, a sum-SE maximization algorithm with the sequential convex approximation(SCA) is proposed, subject to each AP power constraint and SIC power constraint. Numerical experiments indicate that the proposed sum-SE maximization algorithms have a fast converge rate, within about five iterations. In addition, compared with the full power control(FPC) scheme, our algorithms can significantly improve the achievable sum-SE. Moreover, NOMA outperforms OMA in many respects in the presence of the proposed algorithms.
基金financially supported by the National Natural Science Foundation of China (Nos.51674068,51874079 and 11775226)the Natural Science Foundation of Hebei Province (Nos.E2018501091 and E2020501001)+4 种基金the Science and Technology Project of Hebei Province (No.15271302D)the Training Foundation for Scientific Research of Talents Project,Hebei Province (No.A2016005004)the Natural Science Foundation of Liaoning Province (No.2019-MS-110)the Fundamental Research Funds for the Central Universities (Nos.N182306001,N172302001,N172304044 and N182304015)Qinhuangdao City University Student of Science and Technology Innovation and Entrepreneurship Project (Nos.PZB1810008T-46 and PZB1810008T-14)。
文摘In this paper,biocarbon was prepared from corn husks as anode materials for potassium ion batteries at temperatures ranging from 700 to 1600℃.The prepared biocarbon materials have amorphous phase structure and possess larger interlayer spacing than graphite.The biocarbon exhibits enhanced graphitic degree and decreased amounts of surface defects,while the carbonization temperature gradually increases.The obtained potassium ion battery electrode at 1300℃ acquired high reversible capacity up to 216.6 mAh·g^(-1) at 0.1 A·g^(-1) after 100 cycles, and retained 128.6 mAh·g^(-1) at 1 A·g^(-1) even after500 cycles.The results indicate that the samples prepared at 1300℃ have better electrochemical performance than other samples prepared at different temperatures,which was attributed to the decisive influence of microstructure on surface-induced and intercalating potassium storage.
