Located in northwest Beijing, Zhongguancun is often referred to as China＇s very own Silicon Valley. However, the current reputation of this neighborhood as a hub of advanced Chinese technology contrasts sharply with...Located in northwest Beijing, Zhongguancun is often referred to as China＇s very own Silicon Valley. However, the current reputation of this neighborhood as a hub of advanced Chinese technology contrasts sharply with its traditional cliched image. Only a few years ago, this place was one of the largest wholesale markets for electronic products. The way Zhongg-uancun was able to transi tion toward innovation by attracting startups continues to surprise visitors, whether Chinese or foreigners.展开更多
Based on the Regional Specialized Meteorological Center(RSMC)Tokyo-Typhoon Center best-track data and the NCEP-NCAR reanalysis dataset,extratropical transitioning(ET)tropical cyclones(ETCs)over the western North Pacif...Based on the Regional Specialized Meteorological Center(RSMC)Tokyo-Typhoon Center best-track data and the NCEP-NCAR reanalysis dataset,extratropical transitioning(ET)tropical cyclones(ETCs)over the western North Pacific(WNP)during 1951–2021 are classified into six clusters using the fuzzy c-means clustering method(FCM)according to their track patterns.The characteristics of the six hard-clustered ETCs with the highest membership coefficient are shown.Most tropical cyclones(TCs)that were assigned to clusters C2,C5,and C6 made landfall over eastern Asian countries,which severely threatened these regions.Among landfalling TCs,93.2%completed their ET after landfall,whereas 39.8%of ETCs completed their transition within one day.The frequency of ETCs over the WNP has decreased in the past four decades,wherein cluster C5 demonstrated a significant decrease on both interannual and interdecadal timescales with the expansion and intensification of the western Pacific subtropical high(WPSH).This large-scale circulation pattern is favorable for C2 and causes it to become the dominant track pattern,owning to it containing the largest number of intensifying ETCs among the six clusters,a number that has increased insignificantly over the past four decades.The surface roughness variation and three-dimensional background circulation led to C5 containing the maximum number of landfalling TCs and a minimum number of intensifying ETCs.Our results will facilitate a better understanding of the spatiotemporal distributions of ET events and associated environment background fields,which will benefit the effective monitoring of these events over the WNP.展开更多
This paper presents the views of 623 informal and formal small,medium,and micro enterprises(SMMEs)operating in the Gauteng Province of South Africa.The objective of the study was to identify challenges and benefits th...This paper presents the views of 623 informal and formal small,medium,and micro enterprises(SMMEs)operating in the Gauteng Province of South Africa.The objective of the study was to identify challenges and benefits that are experienced by SMMEs during and after the registration process leading to the transition from informal to formal business,the level of awareness by the SMMEs of the registration information,and the procedures in addition to the potential factors that inspire or discourage informal and prospective business registration.The reason for including both informal and formal SMMEs in the survey was to compare the perceptions of these groups of businesses regarding the triggers and/or barriers to register as a formal business.The results show that for both informal and formal businesses,the liability of paying taxes was a major challenge while improved workers’health and safety accrued as a major benefit.Own research emerged as the main source of access to business registration information and procedure.The costs involved in registration were highlighted as one of the major factors discouraging registration but the prospects of expanding the customer base and the ability to achieve a higher turnover as some of the main inspiring factors.The study recommends the development of policies that provide an enabling environment for sustainable enterprises but also to implement measures that improve productivity through access to finance,skills,infrastructure,markets,and technology transfers.展开更多
Original reference:iEnergy,3(1):46-58,2024 Grid-tie voltage source converters(VSCs)can operate in three distinct modes:AC-dominant,DC-dominant,and balanced,depending on the placement of the stiff voltage sources,as sh...Original reference:iEnergy,3(1):46-58,2024 Grid-tie voltage source converters(VSCs)can operate in three distinct modes:AC-dominant,DC-dominant,and balanced,depending on the placement of the stiff voltage sources,as shown in Figure 1.The distinct operation modes of VSCs typically require different synchronization control techniques.For instance,the grid-following(GFL)control,which utilizes a phase-locked loop to track the AC grid phase and frequency,can be employed for VSCs operating in the AC-dominant mode and the balanced mode.On the other hand,the grid-forming(GFM)control is uti-lized for VSCs operating in the DC-dominant mode and the bal-anced mode.Therefore,neither GFM control nor GFL control can serve as a universal synchronization control technique for VSCs to operate in all of the three modes.While the combination of the GFL VSCs and the GFM VSCs can handle applications that require the VSCs to operate in all of the three modes,effectively accommodating and coordinating the heterogeneous GFL and GFM VSCs remains challenging for power systems.展开更多
Original reference:iEnergy,2(2):93-99,2023 Droplet-based triboelectric nanogenerator(D-TENG)using liquid-solid contact electrification has been widely studied for harvesting raindrop energy and ocean energy due to its...Original reference:iEnergy,2(2):93-99,2023 Droplet-based triboelectric nanogenerator(D-TENG)using liquid-solid contact electrification has been widely studied for harvesting raindrop energy and ocean energy due to its unique ability to effectively reduce friction between solids and improve durability.In 2020,a new-generation D-TENG with a“transistor-like”struc-ture was proposed,which first achieved ultra-high instantaneous power output(50 W/m2).Subsequently,D-TENG has been rapidly developed and is widely used in ocean wave energy power gener-ation and liquid-solid triboelectric power generation.Currently,although we have excellent D-TENGs to harvest energy from a single water droplet,but if multiple D-TENGs are simply connected in parallel for a large area usage,the output power of the whole power generation module will drop significantly due to the mutual influence between different individual generation units,which severely limits their applications in practice.Therefore,finding a reasonable topology to relieve the inherent constraints of D-TENGs is of great significance for realizing the large-scale rain-drop energy harvesting.展开更多
Human pluripotent stem cells provide an inexhaustible model to study human embryogenesis in vitro.Recent studies have provided diverse models to generate human blastoids by self-organization of different pluripotent s...Human pluripotent stem cells provide an inexhaustible model to study human embryogenesis in vitro.Recent studies have provided diverse models to generate human blastoids by self-organization of different pluripotent stem cells or somatic reprogramming intermediates.However,whether blastoids can be generated from other cell types or whether they can recapitulate postimplantation development in vitro is unknown.Here,we develop a strategy to generate human blastoids from heterogeneous intermediates with epiblast,trophectoderm,and primitive endoderm signatures of the primed-to-naïve conversion process,which resemble natural blastocysts in morphological architecture,composition of cell lineages,transcriptome,and lineage differentiation potential.In addition,these blastoids reflect many features of human peri-implantation and pregastrulation development when further cultured in an in vitro 3D culture system.In summary,our study provides an alternative strategy to generate human blastoids and offers insights into human early embryogenesis by modeling peri-and postimplantation development in vitro.展开更多
Dynamic thermal mechanical analysis was used to evaluate the viscoelasticity of asphalt.The parameters included the energy storage modulus(E),the loss modulus(E'),and the loss tangent(tanδ).The impact of three ki...Dynamic thermal mechanical analysis was used to evaluate the viscoelasticity of asphalt.The parameters included the energy storage modulus(E),the loss modulus(E'),and the loss tangent(tanδ).The impact of three kinds of particles containing CaCO_(3)with different size and structure on the mechanical properties was also measured.The addition of limestone increases the glass transition temperature,while nanoCaCO_(3)@SiO_(2)decreases the glass transition temperature.Nano-CaCO_(3)has a negligible effect on the glass transition temperature.The particle size of the limestone is 0.075 mm,which is a material at the micrometer level.During the heating process,it hinders the molecular movement and makes the material harder.Thus the glass transition temperature is relatively high.展开更多
The moment a media delegation from the Republic of the Congo arrived at the Othello Kitchenware Museum on 18 November 2025,they were greeted with a vivid show of Guangdong’s industrial strength.Standing before them w...The moment a media delegation from the Republic of the Congo arrived at the Othello Kitchenware Museum on 18 November 2025,they were greeted with a vivid show of Guangdong’s industrial strength.Standing before them was not a typical exhibition hall,but a building shaped like a gleaming stainless-steel cooking pot.展开更多
Crushing waste coral concrete into recycled aggregates to create recycled coral aggregate concrete(RCAC)contributes to sustainable construction development on offshore islands and reefs.To investigate the impact of re...Crushing waste coral concrete into recycled aggregates to create recycled coral aggregate concrete(RCAC)contributes to sustainable construction development on offshore islands and reefs.To investigate the impact of recycled coral aggregate on concrete properties,this study performed a comprehensive analysis of the physical properties of recycled coral aggregate and the basic mechanical properties and microstructure of RCAC.The test results indicate that,compared to coral debris,the crushing index of recycled coral aggregate was reduced by 9.4%,while porosity decreased by 33.5%.Furthermore,RCAC retained the early strength characteristics of coral concrete,with compressive strength and flexural strength exhibiting a notable increase as the water-cement ratio decreased.Under identical conditions,the compressive strength and flexural strength of RCAC were 12.7% and 2.5% higher than coral concrete's,respectively,with porosity correspondingly reduced from 3.13% to 5.11%.This enhancement could be attributed to the new mortar filling the recycled coral aggregate.Scanning electron microscopy(SEM)analysis revealed three distinct interface transition zones within RCAC,with the‘new mortar-old mortar’interface identified as the weakest.The above findings provided a reference for the sustainable use of coral concrete in constructing offshore islands.展开更多
The cyclone phase space （CPS） method has been utilized to evaluate the extratropical transition （ET） of tropical cyclones （TCs） in many recent publications. However, these studies mainly focused over the North A...The cyclone phase space （CPS） method has been utilized to evaluate the extratropical transition （ET） of tropical cyclones （TCs） in many recent publications. However, these studies mainly focused over the North Atlantic basin. In this paper, the CPS characteristics of all the cyclones over the western North Pacific are investigated and discussed, with three parameters calculated from the best-track data of the Regional Specialized Meteorological Center in Tokyo and the Japanese 25-yr reanalysis data. It is concluded that most TCs over the western North Pacific possess the non-frontal and warm-core structure, while a larger number of cyclones that have undergone ET hold the frontal and cold-core structure. The spatial pattern of the CPS parameters indicates that the areas of tropical and extratropical cyclone activities could be demarcated by 30 - N. The composite and individual series of three parameters of the CPS indicate that the transformation of –V U T from positive to negative leads to the start of ET, and could be considered as a potential predictor in operationally forecasting an ET event.展开更多
This paper proposes a novel modified uni-traveling-carrier photodiode(MUTC-PD)featuring an electric field regulation layer:a p-type doped thin layer inserted behind the PD’s n-doped cliff layer.This electric field re...This paper proposes a novel modified uni-traveling-carrier photodiode(MUTC-PD)featuring an electric field regulation layer:a p-type doped thin layer inserted behind the PD’s n-doped cliff layer.This electric field regulation layer enhances the PD’s performance by not only reducing and smoothing the electric field intensity in the collector layer,allowing photo-generated electrons to transit at peak drift velocity,but also improving the electric field intensity in the depleted absorber layer and optimizing the photo-generated carriers’saturated transit performance.Additionally,the transport characteristics of the peak drift velocity of photogenerated electrons in the device’s collection layer can be used to optimize its parasitic characteristics.The electron’s peak drift velocity compensates for the lost transit time.Thus improving the 3 dB bandwidth of the PD’s photo response.Finally obtains a MUTC-PD with a 3 dB bandwidth of 68 GHz at a responsivity of 0.502 A/W,making it suitable for 100 Gbit/s optical receivers.展开更多
In recent years,sodium-ion batteries(SIBs)have become one of the hot discussions and have gradually moved toward industrialization.However,there are still some shortcomings in their performance that have not been well...In recent years,sodium-ion batteries(SIBs)have become one of the hot discussions and have gradually moved toward industrialization.However,there are still some shortcomings in their performance that have not been well addressed,including phase transition,structural degradation,and voltage platform.High entropy materials have recently gained significant attention from researchers due to their effects on thermodynamics,dynamics,structure,and performance.Researchers have attempted to use these materials in sodium-ion batteries to overcome their problems,making it a modification method.This paper aims to discuss the research status of high-entropy cathode materials for sodium-ion batteries and summarize their effects on sodium-ion batteries from three perspectives:Layered oxide,polyanion,and Prussian blue.The infiuence on material structure,the inhibition of phase transition,and the improvement of ion diffusivity are described.Finally,the advantages and disadvantages of high-entropy cathode materials for sodium-ion batteries are summarized,and their future development has prospected.展开更多
For the development of high-performance metallic glasses,enhancing their stability against viscous flow and crystallization is a primary objective.Vapor deposition or prolonged annealing is an effective method to impr...For the development of high-performance metallic glasses,enhancing their stability against viscous flow and crystallization is a primary objective.Vapor deposition or prolonged annealing is an effective method to improve glass stability,shown by increased glass transition temperature(Tg)and crystallization temperature(Tx).This contributes to the development of ultra-stable metallic glasses.Herein,we demonstrate that modulating the quenching temperature can also produce ultra-stable metallic glasses,as evidenced by an increase in Tx of 17-30 K in Cu-based metallic glasses.By modulating the quenching temperature,separated primary phases,secondary phases,and even nano-oxides can be obtained in the metallic glasses.Notably,metastable phases such as Cu-rich precipitates arising from secondary phase separation play a crucial role in enhancing glass stability.However,the enhancement of the stability of the glass has only a negligible effect on its mechanical properties.This study implies that different melt thermodynamic states generated by liquid-liquid separation and transition collectively determine the frozen-in glass structure.The results of this study will be helpful for the development of ultra-stable bulk glasses.展开更多
By reviewing the research progress and exploration practices of shale gas geology in China,analyzing and summarizing the geological characteristics,enrichment laws,and resource potential of different types of shale ga...By reviewing the research progress and exploration practices of shale gas geology in China,analyzing and summarizing the geological characteristics,enrichment laws,and resource potential of different types of shale gas,the following understandings have been obtained:(1)Marine,transitional,and lacustrine shales in China are distributed from old to new in geological age,and the complexity of tectonic reworking and hydrocarbon generation evolution processes gradually decreases.(2)The sedimentary environment controls the type of source-reservoir configuration,which is the basis of“hydrocarbon generation and reservoir formation”.The types of source-reservoir configuration in marine and lacustrine shales are mainly source-reservoir integration,with occasional source-reservoir separation.The configuration types of transitional shale are mainly source-reservoir integration and source-reservoir symbiosis.(3)The resistance of rigid minerals to compression for pore preservation and the overpressure facilitate the enrichment of source-reservoir integrated shale gas.Good source reservoir coupling and preservation conditions are crucial for the shale gas enrichment of source-reservoir symbiosis and source-reservoir separation types.(4)Marine shale remains the main battlefield for increasing shale gas reserves and production in China,while transitional and lacustrine shales are expected to become important replacement areas.It is recommended to carry out the shale gas exploration at three levels:Accelerate the exploration of Silurian,Cambrian,and Permian marine shales in the Upper-Middle Yangtze region;make key exploration breakthroughs in ultra-deep marine shales of the Upper-Middle Yangtze region,the new Ordovician marine shale strata in the North China region,the transitional shales of the Carboniferous and Permian,as well as the Mesozoic lacustrine shale gas in basins such as Sichuan,Ordos and Songliao;explore and prepare for new shale gas exploration areas such as South China and Northwest China,providing technology and resource reserves for the sustainable development of shale gas in China.展开更多
Reasonable manipulation of component and microstructure is considered as a potential route to realize high-performance microwave absorber.In this paper,micro-sized hexapod-like CuS/Cu_(9)S_(5) composites were synthesi...Reasonable manipulation of component and microstructure is considered as a potential route to realize high-performance microwave absorber.In this paper,micro-sized hexapod-like CuS/Cu_(9)S_(5) composites were synthesized via a facile approach involving the solvothermal method and subsequent sulfuration treatment.The resultant CuS/Cu_(9)S_(5) exhibited superb microwave absorbing capacity with a minimum reflection loss(RLmin)of-59.38 dB at 2.7 mm.The maximum effective absorption bandwidth(EABmax)was 7.44 GHz(10.56-18 GHz)when the thickness was reduced to 2.3 mm.The outstanding microwave absorbing ability of CuS/Cu_(9)S_(5) composites is mainly related to its unique hexapod shape and the formation of heterogeneous interfaces.The unique hexapod shape significantly promotes the multi-reflection of the incident electromagnetic wave(EMW)increasing the attenuation path of EMWs in the material.Hetero-geneous interfaces between CuS/Cu_(9)S_(5) enable powerful interface polarization,contributing to the atten-uation of EMWs propagating in the medium.In addition,the EMW absorption performance of CuS/Cu_(9)S_(5) composites is also inseparable from the conduction loss.This study provides a strong reference for the research of EMW absorbent materials based on transition metal sulfides.展开更多
The triple bond in N_(2)has an extremely high bond energy and is thus difficult to break.N_(2)is commonly converted into NH3 artificially via the Haber-Bosch process,and NH_(3)can be utilized to produce other nitrogen...The triple bond in N_(2)has an extremely high bond energy and is thus difficult to break.N_(2)is commonly converted into NH3 artificially via the Haber-Bosch process,and NH_(3)can be utilized to produce other nitrogen-containing chemicals.Here,we developed an electron catalyzed method to directly fix N_(2)into azos,by pushing and pulling the electron into and from the aromatic halide with the cyclic voltammetry method.The round-trip journey of electron can successfully weaken the triple bond in N_(2)through the electron pushing-induced aryl radical via a“brick trowel”transition state,and then produce the diazonium ions by pulling the electron out from the diazo radical intermediate.Different azos can be synthesized with this developed electron catalyzed approach.This approach provides a novel concept and practical route for the fixation of N_(2)at atmospheric pressure into chemical products valuable for industrial and commercial applications.展开更多
Layered transition metal oxides have emerged as promising cathode materials for sodium ion batteries.However,irreversible phase transitions cause structural distortion and cation rearrangement,leading to sluggish Na+d...Layered transition metal oxides have emerged as promising cathode materials for sodium ion batteries.However,irreversible phase transitions cause structural distortion and cation rearrangement,leading to sluggish Na+dynamics and rapid capacity decay.In this study,we propose a medium-entropy cathode by simultaneously introducing Fe,Mg,and Li dopants into a typical P2-type Na_(0.75)Ni_(0.25)Mn_(0.75)O_(2)cathode.The modified Na_(0.75)Ni_(0.2125)Mn_(0.6375)Fe_(0.05)Mg_(0.05)Li_(0.05)O_(2)cathode predominantly exhibits a main P2 phase(93.5%)with a minor O3 phase(6.5%).Through spectroscopy techniques and electrochemical investigations,we elucidate the redox mechanisms of Ni^(2+/3+/4+),Mn^(3+/4+),Fe^(3+/4+),and O_(2)-/O_(2)^(n-)during charging/discharging.The medium-entropy doping mitigates the detrimental P2-O_(2)phase transition at high-voltage,replacing it with a moderate and reversible structural evolution(P2-OP4),thereby enhancing structural stability.Consequently,the modified cathode exhibits a remarkable rate capacity of 108.4 mAh·g^(-1)at 10C,with a capacity retention of 99.0%after 200 cycles at 1C,82.5%after 500 cycles at 5C,and 76.7%after 600 cycles at 10C.Furthermore,it also demonstrates superior electrochemical performance at high cutoff voltage of 4.5 V and extreme temperature(55 and 0℃).This work offers solutions to critical challenges in sodium ion batteries cathode materials.展开更多
Exosomes have shown good potential in ischemic injury disease treatments.However,evidence about their effect and molecular mechanisms in osteonecrosis of femoral head(ONFH)treatment is still limited.Here,we revealed t...Exosomes have shown good potential in ischemic injury disease treatments.However,evidence about their effect and molecular mechanisms in osteonecrosis of femoral head(ONFH)treatment is still limited.Here,we revealed the cell biology characters of ONFH osteonecrosis area bone tissue in single cell scale and thus identified a novel ONFH treatment approach based on M2 macrophages-derived exosomes(M2-Exos).We further show that M2-Exos are highly effective in the treatment of ONFH by modulating the phenotypes communication between neutrophil and endothelium including neutrophil extracellular traps formation and endothelial phenotype transition.Additionally,we identified that M2-Exos’therapeutic effect is attributed to the high content of miR-93-5p and constructed miR-93-5p overexpression model in vitro and in vivo based on lentivirus and adenoassociated virus respectively.Then we found miR-93-5p can not only reduce neutrophil extracellular traps formation but also improve angiogenic ability of endothelial cells.These results provided a new theoretical basis for the clinical application of ONFH therapeutic exosomes.展开更多
There is a growing recognition of the critical role of security governance in advancing democratic transition in the post-conflict environment.Despite such a recognition,the security sector reform concept has overshad...There is a growing recognition of the critical role of security governance in advancing democratic transition in the post-conflict environment.Despite such a recognition,the security sector reform concept has overshadowed the importance of the overarching strategic role of security governance in transition to democracy,particularly in Africa.This paper assesses the status and challenges facing security governance and how they thwarted the efforts to furthering the democratic transition in South Sudan.The paper shows a deterioration in security,safety and security governance outcomes since the independence of South Sudan in 2011 with such a trend unlikely to be abated in the near future without strategic interventions.Some of the challenges facing security governance in South Sudan include the legacies of some historical events including the“Big Tent Policy”,absence of strategic leadership,lack of overarching policy framework,impractical and tenuous security arrangements in the 2018 peace agreement,persistent postponement of the first elections,and dysfunctional justice sector.The paper provides some strategic and operational recommendations to improve security governance and advance democratic transition in South Sudan.These recommendations include formulation of an inclusive and people-centered national security policy,rigorous judicial reform,and early political agreement on new political infrastructure if conditions for holding the first national elections are not met in 2026.展开更多
文摘Located in northwest Beijing, Zhongguancun is often referred to as China＇s very own Silicon Valley. However, the current reputation of this neighborhood as a hub of advanced Chinese technology contrasts sharply with its traditional cliched image. Only a few years ago, this place was one of the largest wholesale markets for electronic products. The way Zhongg-uancun was able to transi tion toward innovation by attracting startups continues to surprise visitors, whether Chinese or foreigners.
基金supported by the National Natural Science Foundation of China(Grant Nos.42075053 and 41975128)。
文摘Based on the Regional Specialized Meteorological Center(RSMC)Tokyo-Typhoon Center best-track data and the NCEP-NCAR reanalysis dataset,extratropical transitioning(ET)tropical cyclones(ETCs)over the western North Pacific(WNP)during 1951–2021 are classified into six clusters using the fuzzy c-means clustering method(FCM)according to their track patterns.The characteristics of the six hard-clustered ETCs with the highest membership coefficient are shown.Most tropical cyclones(TCs)that were assigned to clusters C2,C5,and C6 made landfall over eastern Asian countries,which severely threatened these regions.Among landfalling TCs,93.2%completed their ET after landfall,whereas 39.8%of ETCs completed their transition within one day.The frequency of ETCs over the WNP has decreased in the past four decades,wherein cluster C5 demonstrated a significant decrease on both interannual and interdecadal timescales with the expansion and intensification of the western Pacific subtropical high(WPSH).This large-scale circulation pattern is favorable for C2 and causes it to become the dominant track pattern,owning to it containing the largest number of intensifying ETCs among the six clusters,a number that has increased insignificantly over the past four decades.The surface roughness variation and three-dimensional background circulation led to C5 containing the maximum number of landfalling TCs and a minimum number of intensifying ETCs.Our results will facilitate a better understanding of the spatiotemporal distributions of ET events and associated environment background fields,which will benefit the effective monitoring of these events over the WNP.
文摘This paper presents the views of 623 informal and formal small,medium,and micro enterprises(SMMEs)operating in the Gauteng Province of South Africa.The objective of the study was to identify challenges and benefits that are experienced by SMMEs during and after the registration process leading to the transition from informal to formal business,the level of awareness by the SMMEs of the registration information,and the procedures in addition to the potential factors that inspire or discourage informal and prospective business registration.The reason for including both informal and formal SMMEs in the survey was to compare the perceptions of these groups of businesses regarding the triggers and/or barriers to register as a formal business.The results show that for both informal and formal businesses,the liability of paying taxes was a major challenge while improved workers’health and safety accrued as a major benefit.Own research emerged as the main source of access to business registration information and procedure.The costs involved in registration were highlighted as one of the major factors discouraging registration but the prospects of expanding the customer base and the ability to achieve a higher turnover as some of the main inspiring factors.The study recommends the development of policies that provide an enabling environment for sustainable enterprises but also to implement measures that improve productivity through access to finance,skills,infrastructure,markets,and technology transfers.
文摘Original reference:iEnergy,3(1):46-58,2024 Grid-tie voltage source converters(VSCs)can operate in three distinct modes:AC-dominant,DC-dominant,and balanced,depending on the placement of the stiff voltage sources,as shown in Figure 1.The distinct operation modes of VSCs typically require different synchronization control techniques.For instance,the grid-following(GFL)control,which utilizes a phase-locked loop to track the AC grid phase and frequency,can be employed for VSCs operating in the AC-dominant mode and the balanced mode.On the other hand,the grid-forming(GFM)control is uti-lized for VSCs operating in the DC-dominant mode and the bal-anced mode.Therefore,neither GFM control nor GFL control can serve as a universal synchronization control technique for VSCs to operate in all of the three modes.While the combination of the GFL VSCs and the GFM VSCs can handle applications that require the VSCs to operate in all of the three modes,effectively accommodating and coordinating the heterogeneous GFL and GFM VSCs remains challenging for power systems.
文摘Original reference:iEnergy,2(2):93-99,2023 Droplet-based triboelectric nanogenerator(D-TENG)using liquid-solid contact electrification has been widely studied for harvesting raindrop energy and ocean energy due to its unique ability to effectively reduce friction between solids and improve durability.In 2020,a new-generation D-TENG with a“transistor-like”struc-ture was proposed,which first achieved ultra-high instantaneous power output(50 W/m2).Subsequently,D-TENG has been rapidly developed and is widely used in ocean wave energy power gener-ation and liquid-solid triboelectric power generation.Currently,although we have excellent D-TENGs to harvest energy from a single water droplet,but if multiple D-TENGs are simply connected in parallel for a large area usage,the output power of the whole power generation module will drop significantly due to the mutual influence between different individual generation units,which severely limits their applications in practice.Therefore,finding a reasonable topology to relieve the inherent constraints of D-TENGs is of great significance for realizing the large-scale rain-drop energy harvesting.
基金the Ministry of Science and Technology of China(Nos.2021YFA1102000,2021YFC2700300,2019YFA0110000,and 2018YFA0108900)the National Natural Science Foundation of China(NSFC)(Nos.31721003,32022024,32270850,32100633,31871486,32070652,and 81630035)the Science and Technology Commission of Shanghai Municipality(Nos.19JC1415300 and 21JC1405500).
文摘Human pluripotent stem cells provide an inexhaustible model to study human embryogenesis in vitro.Recent studies have provided diverse models to generate human blastoids by self-organization of different pluripotent stem cells or somatic reprogramming intermediates.However,whether blastoids can be generated from other cell types or whether they can recapitulate postimplantation development in vitro is unknown.Here,we develop a strategy to generate human blastoids from heterogeneous intermediates with epiblast,trophectoderm,and primitive endoderm signatures of the primed-to-naïve conversion process,which resemble natural blastocysts in morphological architecture,composition of cell lineages,transcriptome,and lineage differentiation potential.In addition,these blastoids reflect many features of human peri-implantation and pregastrulation development when further cultured in an in vitro 3D culture system.In summary,our study provides an alternative strategy to generate human blastoids and offers insights into human early embryogenesis by modeling peri-and postimplantation development in vitro.
基金Funded by National Natural Science Foundation of China(No.52472033)。
文摘Dynamic thermal mechanical analysis was used to evaluate the viscoelasticity of asphalt.The parameters included the energy storage modulus(E),the loss modulus(E'),and the loss tangent(tanδ).The impact of three kinds of particles containing CaCO_(3)with different size and structure on the mechanical properties was also measured.The addition of limestone increases the glass transition temperature,while nanoCaCO_(3)@SiO_(2)decreases the glass transition temperature.Nano-CaCO_(3)has a negligible effect on the glass transition temperature.The particle size of the limestone is 0.075 mm,which is a material at the micrometer level.During the heating process,it hinders the molecular movement and makes the material harder.Thus the glass transition temperature is relatively high.
文摘The moment a media delegation from the Republic of the Congo arrived at the Othello Kitchenware Museum on 18 November 2025,they were greeted with a vivid show of Guangdong’s industrial strength.Standing before them was not a typical exhibition hall,but a building shaped like a gleaming stainless-steel cooking pot.
基金Funded by Natural Science Foundation of Guangxi(No.2025GXNSFBA069565)Guangxi Science and Technology Program(No.AD25069101)Guangxi Bagui Scholars Fund。
文摘Crushing waste coral concrete into recycled aggregates to create recycled coral aggregate concrete(RCAC)contributes to sustainable construction development on offshore islands and reefs.To investigate the impact of recycled coral aggregate on concrete properties,this study performed a comprehensive analysis of the physical properties of recycled coral aggregate and the basic mechanical properties and microstructure of RCAC.The test results indicate that,compared to coral debris,the crushing index of recycled coral aggregate was reduced by 9.4%,while porosity decreased by 33.5%.Furthermore,RCAC retained the early strength characteristics of coral concrete,with compressive strength and flexural strength exhibiting a notable increase as the water-cement ratio decreased.Under identical conditions,the compressive strength and flexural strength of RCAC were 12.7% and 2.5% higher than coral concrete's,respectively,with porosity correspondingly reduced from 3.13% to 5.11%.This enhancement could be attributed to the new mortar filling the recycled coral aggregate.Scanning electron microscopy(SEM)analysis revealed three distinct interface transition zones within RCAC,with the‘new mortar-old mortar’interface identified as the weakest.The above findings provided a reference for the sustainable use of coral concrete in constructing offshore islands.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 40830958 and 40730948the "973" Program of China under Grant No. 2009CB421502the National Rescarch Fund for Public Welfare under Grant Nos. GYHY200906011 and GYHY201006007
文摘The cyclone phase space （CPS） method has been utilized to evaluate the extratropical transition （ET） of tropical cyclones （TCs） in many recent publications. However, these studies mainly focused over the North Atlantic basin. In this paper, the CPS characteristics of all the cyclones over the western North Pacific are investigated and discussed, with three parameters calculated from the best-track data of the Regional Specialized Meteorological Center in Tokyo and the Japanese 25-yr reanalysis data. It is concluded that most TCs over the western North Pacific possess the non-frontal and warm-core structure, while a larger number of cyclones that have undergone ET hold the frontal and cold-core structure. The spatial pattern of the CPS parameters indicates that the areas of tropical and extratropical cyclone activities could be demarcated by 30 - N. The composite and individual series of three parameters of the CPS indicate that the transformation of –V U T from positive to negative leads to the start of ET, and could be considered as a potential predictor in operationally forecasting an ET event.
文摘This paper proposes a novel modified uni-traveling-carrier photodiode(MUTC-PD)featuring an electric field regulation layer:a p-type doped thin layer inserted behind the PD’s n-doped cliff layer.This electric field regulation layer enhances the PD’s performance by not only reducing and smoothing the electric field intensity in the collector layer,allowing photo-generated electrons to transit at peak drift velocity,but also improving the electric field intensity in the depleted absorber layer and optimizing the photo-generated carriers’saturated transit performance.Additionally,the transport characteristics of the peak drift velocity of photogenerated electrons in the device’s collection layer can be used to optimize its parasitic characteristics.The electron’s peak drift velocity compensates for the lost transit time.Thus improving the 3 dB bandwidth of the PD’s photo response.Finally obtains a MUTC-PD with a 3 dB bandwidth of 68 GHz at a responsivity of 0.502 A/W,making it suitable for 100 Gbit/s optical receivers.
基金the National Natural Science Foundation of China Key Program(No.U22A20420)Changzhou Leading Innovative Talents Introduction and Cultivation Project(No.CQ20230109)for supporting our work。
文摘In recent years,sodium-ion batteries(SIBs)have become one of the hot discussions and have gradually moved toward industrialization.However,there are still some shortcomings in their performance that have not been well addressed,including phase transition,structural degradation,and voltage platform.High entropy materials have recently gained significant attention from researchers due to their effects on thermodynamics,dynamics,structure,and performance.Researchers have attempted to use these materials in sodium-ion batteries to overcome their problems,making it a modification method.This paper aims to discuss the research status of high-entropy cathode materials for sodium-ion batteries and summarize their effects on sodium-ion batteries from three perspectives:Layered oxide,polyanion,and Prussian blue.The infiuence on material structure,the inhibition of phase transition,and the improvement of ion diffusivity are described.Finally,the advantages and disadvantages of high-entropy cathode materials for sodium-ion batteries are summarized,and their future development has prospected.
基金supported by the National Natural Science Foundation of China(Nos.51827801,52371152,and 51971120).
文摘For the development of high-performance metallic glasses,enhancing their stability against viscous flow and crystallization is a primary objective.Vapor deposition or prolonged annealing is an effective method to improve glass stability,shown by increased glass transition temperature(Tg)and crystallization temperature(Tx).This contributes to the development of ultra-stable metallic glasses.Herein,we demonstrate that modulating the quenching temperature can also produce ultra-stable metallic glasses,as evidenced by an increase in Tx of 17-30 K in Cu-based metallic glasses.By modulating the quenching temperature,separated primary phases,secondary phases,and even nano-oxides can be obtained in the metallic glasses.Notably,metastable phases such as Cu-rich precipitates arising from secondary phase separation play a crucial role in enhancing glass stability.However,the enhancement of the stability of the glass has only a negligible effect on its mechanical properties.This study implies that different melt thermodynamic states generated by liquid-liquid separation and transition collectively determine the frozen-in glass structure.The results of this study will be helpful for the development of ultra-stable bulk glasses.
基金Supported by the National Natural Science Foundation of China(42172165,42272143)Project of SINOPEC Science and Technology Department(P24181,KLP24017).
文摘By reviewing the research progress and exploration practices of shale gas geology in China,analyzing and summarizing the geological characteristics,enrichment laws,and resource potential of different types of shale gas,the following understandings have been obtained:(1)Marine,transitional,and lacustrine shales in China are distributed from old to new in geological age,and the complexity of tectonic reworking and hydrocarbon generation evolution processes gradually decreases.(2)The sedimentary environment controls the type of source-reservoir configuration,which is the basis of“hydrocarbon generation and reservoir formation”.The types of source-reservoir configuration in marine and lacustrine shales are mainly source-reservoir integration,with occasional source-reservoir separation.The configuration types of transitional shale are mainly source-reservoir integration and source-reservoir symbiosis.(3)The resistance of rigid minerals to compression for pore preservation and the overpressure facilitate the enrichment of source-reservoir integrated shale gas.Good source reservoir coupling and preservation conditions are crucial for the shale gas enrichment of source-reservoir symbiosis and source-reservoir separation types.(4)Marine shale remains the main battlefield for increasing shale gas reserves and production in China,while transitional and lacustrine shales are expected to become important replacement areas.It is recommended to carry out the shale gas exploration at three levels:Accelerate the exploration of Silurian,Cambrian,and Permian marine shales in the Upper-Middle Yangtze region;make key exploration breakthroughs in ultra-deep marine shales of the Upper-Middle Yangtze region,the new Ordovician marine shale strata in the North China region,the transitional shales of the Carboniferous and Permian,as well as the Mesozoic lacustrine shale gas in basins such as Sichuan,Ordos and Songliao;explore and prepare for new shale gas exploration areas such as South China and Northwest China,providing technology and resource reserves for the sustainable development of shale gas in China.
基金supported by the National Natural Science Foundation of China(Nos.52377026 and 52301192)the Taishan Scholars and Young Experts Program of Shandong Province(No.tsqn202103057)+3 种基金the Postdoctoral Fellow-ship Program of CPSF under Grant Number(No.GZB20240327)the Shandong Postdoctoral Science Foundation(No.SDCX-ZG-202400275)the Qingdao Postdoctoral Application Research Project(No.QDBSH20240102023)the Qingchuang Talents Induction Program of Shandong Higher Education Institution(Research and Innovation Team of Structural-Functional Polymer Composites).
文摘Reasonable manipulation of component and microstructure is considered as a potential route to realize high-performance microwave absorber.In this paper,micro-sized hexapod-like CuS/Cu_(9)S_(5) composites were synthesized via a facile approach involving the solvothermal method and subsequent sulfuration treatment.The resultant CuS/Cu_(9)S_(5) exhibited superb microwave absorbing capacity with a minimum reflection loss(RLmin)of-59.38 dB at 2.7 mm.The maximum effective absorption bandwidth(EABmax)was 7.44 GHz(10.56-18 GHz)when the thickness was reduced to 2.3 mm.The outstanding microwave absorbing ability of CuS/Cu_(9)S_(5) composites is mainly related to its unique hexapod shape and the formation of heterogeneous interfaces.The unique hexapod shape significantly promotes the multi-reflection of the incident electromagnetic wave(EMW)increasing the attenuation path of EMWs in the material.Hetero-geneous interfaces between CuS/Cu_(9)S_(5) enable powerful interface polarization,contributing to the atten-uation of EMWs propagating in the medium.In addition,the EMW absorption performance of CuS/Cu_(9)S_(5) composites is also inseparable from the conduction loss.This study provides a strong reference for the research of EMW absorbent materials based on transition metal sulfides.
文摘The triple bond in N_(2)has an extremely high bond energy and is thus difficult to break.N_(2)is commonly converted into NH3 artificially via the Haber-Bosch process,and NH_(3)can be utilized to produce other nitrogen-containing chemicals.Here,we developed an electron catalyzed method to directly fix N_(2)into azos,by pushing and pulling the electron into and from the aromatic halide with the cyclic voltammetry method.The round-trip journey of electron can successfully weaken the triple bond in N_(2)through the electron pushing-induced aryl radical via a“brick trowel”transition state,and then produce the diazonium ions by pulling the electron out from the diazo radical intermediate.Different azos can be synthesized with this developed electron catalyzed approach.This approach provides a novel concept and practical route for the fixation of N_(2)at atmospheric pressure into chemical products valuable for industrial and commercial applications.
基金supported by the National Natural Science Foundation of China(No.21805018)by Sichuan Science and Technology Program(Nos.2022ZHCG0018,2023NSFSC0117 and 2023ZHCG0060)Yibin Science and Technology Program(No.2022JB005)and China Postdoctoral Science Foundation(No.2022M722704).
文摘Layered transition metal oxides have emerged as promising cathode materials for sodium ion batteries.However,irreversible phase transitions cause structural distortion and cation rearrangement,leading to sluggish Na+dynamics and rapid capacity decay.In this study,we propose a medium-entropy cathode by simultaneously introducing Fe,Mg,and Li dopants into a typical P2-type Na_(0.75)Ni_(0.25)Mn_(0.75)O_(2)cathode.The modified Na_(0.75)Ni_(0.2125)Mn_(0.6375)Fe_(0.05)Mg_(0.05)Li_(0.05)O_(2)cathode predominantly exhibits a main P2 phase(93.5%)with a minor O3 phase(6.5%).Through spectroscopy techniques and electrochemical investigations,we elucidate the redox mechanisms of Ni^(2+/3+/4+),Mn^(3+/4+),Fe^(3+/4+),and O_(2)-/O_(2)^(n-)during charging/discharging.The medium-entropy doping mitigates the detrimental P2-O_(2)phase transition at high-voltage,replacing it with a moderate and reversible structural evolution(P2-OP4),thereby enhancing structural stability.Consequently,the modified cathode exhibits a remarkable rate capacity of 108.4 mAh·g^(-1)at 10C,with a capacity retention of 99.0%after 200 cycles at 1C,82.5%after 500 cycles at 5C,and 76.7%after 600 cycles at 10C.Furthermore,it also demonstrates superior electrochemical performance at high cutoff voltage of 4.5 V and extreme temperature(55 and 0℃).This work offers solutions to critical challenges in sodium ion batteries cathode materials.
基金the support of the National Natural Science Foundation of China (Grant No.82272503)Natural Science Foundation of Zhejiang Province (Grant No. LQN25H060006)
文摘Exosomes have shown good potential in ischemic injury disease treatments.However,evidence about their effect and molecular mechanisms in osteonecrosis of femoral head(ONFH)treatment is still limited.Here,we revealed the cell biology characters of ONFH osteonecrosis area bone tissue in single cell scale and thus identified a novel ONFH treatment approach based on M2 macrophages-derived exosomes(M2-Exos).We further show that M2-Exos are highly effective in the treatment of ONFH by modulating the phenotypes communication between neutrophil and endothelium including neutrophil extracellular traps formation and endothelial phenotype transition.Additionally,we identified that M2-Exos’therapeutic effect is attributed to the high content of miR-93-5p and constructed miR-93-5p overexpression model in vitro and in vivo based on lentivirus and adenoassociated virus respectively.Then we found miR-93-5p can not only reduce neutrophil extracellular traps formation but also improve angiogenic ability of endothelial cells.These results provided a new theoretical basis for the clinical application of ONFH therapeutic exosomes.
文摘There is a growing recognition of the critical role of security governance in advancing democratic transition in the post-conflict environment.Despite such a recognition,the security sector reform concept has overshadowed the importance of the overarching strategic role of security governance in transition to democracy,particularly in Africa.This paper assesses the status and challenges facing security governance and how they thwarted the efforts to furthering the democratic transition in South Sudan.The paper shows a deterioration in security,safety and security governance outcomes since the independence of South Sudan in 2011 with such a trend unlikely to be abated in the near future without strategic interventions.Some of the challenges facing security governance in South Sudan include the legacies of some historical events including the“Big Tent Policy”,absence of strategic leadership,lack of overarching policy framework,impractical and tenuous security arrangements in the 2018 peace agreement,persistent postponement of the first elections,and dysfunctional justice sector.The paper provides some strategic and operational recommendations to improve security governance and advance democratic transition in South Sudan.These recommendations include formulation of an inclusive and people-centered national security policy,rigorous judicial reform,and early political agreement on new political infrastructure if conditions for holding the first national elections are not met in 2026.
