Synaptic plasticity is essential for maintaining neuronal function in the central nervous system and serves as a critical indicator of the effects of neurodegenerative disease.Glaucoma directly impairs retinal ganglio...Synaptic plasticity is essential for maintaining neuronal function in the central nervous system and serves as a critical indicator of the effects of neurodegenerative disease.Glaucoma directly impairs retinal ganglion cells and their axons,leading to axonal transport dysfuntion,subsequently causing secondary damage to anterior or posterior ends of the visual system.Accordingly,recent evidence indicates that glaucoma is a degenerative disease of the central nervous system that causes damage throughout the visual pathway.However,the effects of glaucoma on synaptic plasticity in the primary visual cortex remain unclear.In this study,we established a mouse model of unilateral chronic ocular hypertension by injecting magnetic microbeads into the anterior chamber of one eye.We found that,after 4 weeks of chronic ocular hypertension,the neuronal somas were smaller in the superior colliculus and lateral geniculate body regions of the brain contralateral to the affected eye.This was accompanied by glial cell activation and increased expression of inflammatory factors.After 8 weeks of ocular hypertension,we observed a reduction in the number of excitatory and inhibitory synapses,dendritic spines,and activation of glial cells in the primary visual cortex contralateral to the affected eye.These findings suggest that glaucoma not only directly damages the retina but also induces alterations in synapses and dendritic spines in the primary visual cortex,providing new insights into the pathogenesis of glaucoma.展开更多
Aiming at the problems of increasing uncertainty of low-carbon generation energy in active distribution network(ADN)and the difficulty of security assessment of distribution network,this paper proposes a two-phase sch...Aiming at the problems of increasing uncertainty of low-carbon generation energy in active distribution network(ADN)and the difficulty of security assessment of distribution network,this paper proposes a two-phase scheduling model for flexible resources in ADN based on probabilistic risk perception.First,a full-cycle probabilistic trend sequence is constructed based on the source-load historical data,and in the day-ahead scheduling phase,the response interval of the flexibility resources on the load and storage side is optimized based on the probabilistic trend,with the probability of the security boundary as the security constraint,and with the economy as the objective.Then in the intraday phase,the core security and economic operation boundary of theADNis screened in real time.Fromthere,it quantitatively senses the degree of threat to the core security and economic operation boundary under the current source-load prediction information,and identifies the strictly secure and low/high-risk time periods.Flexibility resources within the response interval are dynamically adjusted in real-time by focusing on high-risk periods to cope with future core risks of the distribution grid.Finally,the improved IEEE 33-node distribution system is simulated to obtain the flexibility resource scheduling scheme on the load and storage side.Thescheduling results are evaluated from the perspectives of risk probability and flexible resource utilization efficiency,and the analysis shows that the scheduling model in this paper can promote the consumption of low-carbon energy from wind and photovoltaic sourceswhile reducing the operational risk of the distribution network.展开更多
Optical polarizers,which allow the transmission of specific polarization states,are essential components in modern optical systems.Here,we experimentally demonstrate integrated photonic polarizers incorporating reduce...Optical polarizers,which allow the transmission of specific polarization states,are essential components in modern optical systems.Here,we experimentally demonstrate integrated photonic polarizers incorporating reduced graphene oxide(rGO)films.2D graphene oxide(GO)films are integrated onto silicon waveguides and microring resonators(MRRs)with precise control over their thicknesses and sizes,followed by GO reduction via two different methods including uniform thermal reduction and localized photothermal reduction.We measure devices with various lengths,thicknesses,and reduction degrees of GO films.The results show that the devices with rGO exhibit better performance than those with GO,achieving a polarization-dependent loss of~47 dB and a polarization extinction ratio of~16 dB for the hybrid waveguides and MRRs with rGO,respectively.By fitting the experimental results with theory,it is found that rGO exhibits more significant anisotropy in loss,with an anisotropy ratio over 4 times that of GO.In addition,rGO shows higher thermal stability and greater robustness to photothermal reduction than GO.These results highlight the strong potential of rGO films for implementing high-performance polarization selective devices in integrated photonic platforms.展开更多
A minority carrier lifetime of 25.46 μs in a P-type 4H-SiC epilayer has been attained through sequential thermal oxidation and hydrogen annealing. Thermal oxidation can enhance the minority carrier lifetime in the 4H...A minority carrier lifetime of 25.46 μs in a P-type 4H-SiC epilayer has been attained through sequential thermal oxidation and hydrogen annealing. Thermal oxidation can enhance the minority carrier lifetime in the 4H-SiC epilayer by reducing carbon vacancies. However, this process also generates carbon clusters with limited diffusivity and contributes to the enlargement of surface pits on the 4H-SiC. High-temperature hydrogen annealing effectively reduces stacking fault and dislocation density. Moreover, electron spin resonance analysis indicates a significant reduction in carbon vacancy defects after hydrogen annealing. The mechanisms of the elimination of carbon vacancies by hydrogen annealing include the decomposition of carbon clusters formed during thermal oxidation and the low-pressure selective etching by hydrogen,which increases the carbon content on the 4H-SiC surface and facilitates carbon diffusion. Consequently, the combination of thermal oxidation and hydrogen annealing eliminates carbon vacancies more effectively, substantially enhancing the minority carrier lifetime in P-type 4H-SiC. This improvement is advantageous for the application of high-voltage SiC bipolar devices.展开更多
Compared with teenage patients,adult patients generally show a slower rate of tooth movement and more pronounced alveolar bone loss during orthodontic treatment,indicating the maladaptation of alveolar bone homeostasi...Compared with teenage patients,adult patients generally show a slower rate of tooth movement and more pronounced alveolar bone loss during orthodontic treatment,indicating the maladaptation of alveolar bone homeostasis under orthodontic force.However,this phenomenon is not well-elucidated to date,leading to increased treatment difficulties and unsatisfactory treatment outcomes in adult orthodontics.Aiming to provide a comprehensive knowledge and further inspire insightful understanding towards this issue,this review summarizes the current evidence and underlying mechanisms.The age-related abatements in mechanosensing and mechanotransduction in adult cells and periodontal tissue may contribute to retarded and unbalanced bone metabolism,thus hindering alveolar bone reconstruction during orthodontic treatment.To this end,periodontal surgery,physical and chemical cues are being developed to reactivate or rejuvenate the aging periodontium and restore the dynamic equilibrium of orthodontic-mediated alveolar bone metabolism.We anticipate that this review will present a general overview of the role that aging plays in orthodontic alveolar bone metabolism and shed new light on the prospective ways out of the impasse.展开更多
Additive manufacturing(AM)has the potential to transform manufacturing by enabling previously un-thinkable products,digital inventory and delivery,and distributed manufacturing.Here we presented an extrusion-based met...Additive manufacturing(AM)has the potential to transform manufacturing by enabling previously un-thinkable products,digital inventory and delivery,and distributed manufacturing.Here we presented an extrusion-based metal AM method(refer to“SoftTouch”depositionin thefiledpatent)thatis suitablefor making the metal feedstock flowable prior to the deposition through dynamic recrystallization induced grain refinement at elevated temperatures.The flowable metal was extruded out of the printer head like a paste for building dense metal parts with fine equiaxed grains and wrought mechanical properties.Off-the-shelf metal rods were used as feedstock and the printing process was completed in an open-air environment,avoiding pricy powders and costly inert or vacuum conditions.The resulting multi-layer de-posited 6061 aluminum alloys yield strength and ductility comparable to wrought 6061 aluminum alloys after the same T6 heat treatment.The extrusion-based metal AM method can also be advanced as green manufacturing technologies for fabricating novel alloys and composites,adding novel features to existing parts,repairing damaged metal parts,and welding advanced metals for supporting sustainable manufac-turing,in addition to being developed into a cost-effective manufacturing process for the fabrication of dense metal of complex structural forms.展开更多
As a member of the AFF(AF4/FMR2)family,AFF4 is a transcription elongation factor that is a component of the super elongation complex.AFF4 serves as a scaffolding protein that connects transcription factors and promote...As a member of the AFF(AF4/FMR2)family,AFF4 is a transcription elongation factor that is a component of the super elongation complex.AFF4 serves as a scaffolding protein that connects transcription factors and promotes gene transcription through elongation and chromatin remodelling.Here,we investigated the effect of AFF4 on human dental follicle cells(DFCs)in osteogenic differentiation.In this study,we found that small interfering RNA-mediated depletion of AFF4 resulted in decreased alkaline phosphatase(ALP)activity and impaired mineralization.In addition,the expression of osteogenic-related genes(DLX5,SP7,RUNX2 and BGLAP)was significantly downregulated.In contrast,lentivirus-mediated overexpression of AFF4 significantly enhanced the osteogenic potential of human DFCs.Mechanistically,we found that both the mRNA and protein levels of ALKBH1,a critical regulator of epigenetics,changed in accordance with AFF4 expression levels.Overexpression of ALKBH1 in AFF4-depleted DFCs partially rescued the impairment of osteogenic differentiation.Our data indicated that AFF4 promoted the osteogenic differentiation of DFCs by upregulating the transcription of ALKBH1.展开更多
A 4H-SiC trench gate metal-oxide-semiconductor field-effect transistor(UMOSFET)with semi-super-junction shiel-ded structure(SS-UMOS)is proposed and compared with conventional trench MOSFET(CT-UMOS)in this work.The adv...A 4H-SiC trench gate metal-oxide-semiconductor field-effect transistor(UMOSFET)with semi-super-junction shiel-ded structure(SS-UMOS)is proposed and compared with conventional trench MOSFET(CT-UMOS)in this work.The advantage of the proposed structure is given by comprehensive study of the mechanism of the local semi-super-junction structure at the bottom of the trench MOSFET.In particular,the influence of the bias condition of the p-pillar at the bottom of the trench on the static and dynamic performances of the device is compared and revealed.The on-resistance of SS-UMOS with grounded(G)and ungrounded(NG)p-pillar is reduced by 52%(G)and 71%(NG)compared to CT-UMOS,respectively.Additionally,gate ox-ide in the GSS-UMOS is fully protected by the p-shield layer as well as semi-super-junction structure under the trench and p-base regions.Thus,a reduced electric-field of 2 MV/cm can be achieved at the corner of the p-shield layer.However,the quasi-intrinsic protective layer cannot be formed in NGSS-UMOS due to the charge storage effect in the floating p-pillar,resulting in a large electric field of 2.7 MV/cm at the gate oxide layer.Moreover,the total switching loss of GSS-UMOS is 1.95 mJ/cm2 and is reduced by 18%compared with CT-UMOS.On the contrary,the NGSS-UMOS has the slowest overall switching speed due to the weakened shielding effect of the p-pillar and the largest gate-to-drain capacitance among the three.The proposed GSS-UMOS plays an important role in high-voltage and high-frequency applications,and will provide a valuable idea for device design and circuit applications.展开更多
Thermal oxidation and hydrogen annealing were applied on a 100μm thick Al-doped p-type 4H-Si C epitaxial wafer to modulate the minority carrier lifetime,which was investigated by microwave photoconductive decay(μ-PC...Thermal oxidation and hydrogen annealing were applied on a 100μm thick Al-doped p-type 4H-Si C epitaxial wafer to modulate the minority carrier lifetime,which was investigated by microwave photoconductive decay(μ-PCD).The minority carrier lifetime decreased after each thermal oxidation.On the contrary,with the hydrogen annealing time increasing to3 hours,the minority carrier lifetime increased from 1.1μs(as-grown)to 3.14μs and then saturated after the annealing time reached 4 hours.The increase of surface roughness from 0.236 nm to 0.316 nm may also be one of the reasons for limiting the further improvement of the minority carrier lifetimes.Moreover,the whole wafer mappings of minority carrier lifetimes before and after hydrogen annealing were measured and discussed.The average minority carrier lifetime was up to 1.94μs and non-uniformity of carrier lifetime reached 38%after 4-hour hydrogen annealing.The increasing minority carrier lifetimes could be attributed to the double mechanisms of excess carbon atoms diffusion caused by selective etching of Si atoms and passivation of deep-level defects by hydrogen atoms.展开更多
The agricultural scientific research project funding is an important prerequisite for the implementation of agricultural scientific research project,and an essential basic condition to support agricultural research. I...The agricultural scientific research project funding is an important prerequisite for the implementation of agricultural scientific research project,and an essential basic condition to support agricultural research. In recent years,China has paid great attention to the development of scientific research,and increased the input of scientific research funds,but there are some shortcomings in funding management during the implementation of the project. Based on many years of practice,this paper expounds the main problems in the current funding management for agricultural scientific research project,and brings forward the relevant recommendations,in order to provide a reference for the scientific management of agricultural scientific research project funding in the new situation.展开更多
Inter-subtype recombination is the main force for the complexity of HIV-1 genetic diversity,which increases the difficulty of preventing HIV-1 infection and administering antiretroviral therapy for people living with ...Inter-subtype recombination is the main force for the complexity of HIV-1 genetic diversity,which increases the difficulty of preventing HIV-1 infection and administering antiretroviral therapy for people living with HIV.To date,143 circulating recombinant forms(CRFs)have been re-ported globally,43 of which were identified in China.^(1)Moreover,HIV-1 strains that are produced by second-gen-eration combinations,including unique recombinant forms and CRFs,such as CRF105_0108,CRF123_0107,and CRF134_0185.展开更多
Processing emotional and social information are two closely related and evolutionarily conserved fundamental domains that promote survival and health across species[1].However,extensive human neuroimaging studies have...Processing emotional and social information are two closely related and evolutionarily conserved fundamental domains that promote survival and health across species[1].However,extensive human neuroimaging studies have yielded inconsistent findings.For instance,the amygdala,a key brain region engaged in social-affective cognition,often lacks differential“activation”during the“emotional vs.neutral faces”contrast[2],[3].展开更多
The dynamic behavior of a cavitation bubble near an asymmetric hydrofoil is investigated experimentally through high-speed photography and theoretically using a Kelvin impulse model.The typical deformations arising du...The dynamic behavior of a cavitation bubble near an asymmetric hydrofoil is investigated experimentally through high-speed photography and theoretically using a Kelvin impulse model.The typical deformations arising during bubble collapse near the hydrofoil are analyzed qualitatively.The effects of the bubble position and the hydrofoil’s eccentricity angle are analyzed quantitatively.The spatial distribution of the Kelvin impulse near the hydrofoil are explored.Different morphological evolutions of a bubble near an asymmetric hydrofoil are revealed,with B-shaped,heart-shaped,and arc-shaped collapses.The velocity of the bubble interface close to the hydrofoil is significantly affected by the bubble-hydrofoil distance and the hydrofoil’s eccentricity angle,increasing as both the distance and the eccentricity angle grow.It is found that the Kelvin impulse sensitivity varies at different positions with respect to the asymmetric hydrofoil,being higher at the head and tail,and lower in the middle.展开更多
The head-flow rate curve with double humps brings greater challenges to the stable operation of a pump-turbine in pump mode,and the present investigation aims to reveal the formation mechanisms behind it.We performed ...The head-flow rate curve with double humps brings greater challenges to the stable operation of a pump-turbine in pump mode,and the present investigation aims to reveal the formation mechanisms behind it.We performed unsteady simulations by applying a modified partially averaged Navier-Stokes(PANS)model and the double hump phenomenon was satisfactorily captured with relative errors within 3.87%by comparing the head with the experimental data.The results showed that the rotating stall occurred in the guide vane during both the first and second hump regions and induced the dominant pressure pulsation component with an oscillating frequency 11.7%times the runner rotation frequency.The reverse flow was observed due to the propagation of rotating stall cells in the guide vane,and the first hump was attributed to the vortex in the vaneless region,with a reduction in the runner's capacity for doing work as the reverse flow reached the blade trailing edge.The second hump was attributed to the flow separation near the leading edge of the runner blades,which extended to the runner outlet and interacted with the rotating stall cell,leading to a rapid extension of the reverse flow into the runner.This not only reduces the runner's capacity for doing work but also significantly increases the energy loss in the blade-to-blade flow passage near the runner exit.This study enhances the understanding of the flow mechanism in the hump region,which can provide insights into the suppression of unstable flows and runner optimization.展开更多
With more and more lithium-ion batteries(LIBs)being put into production and application,precious metals such as lithium and cobalt are scarce,so it is imminent to recover various strategic metal resources from spent L...With more and more lithium-ion batteries(LIBs)being put into production and application,precious metals such as lithium and cobalt are scarce,so it is imminent to recover various strategic metal resources from spent LIBs.Meanwhile,the complex and difficult problem of separating and recovering metals from leaching solutions has been an urgent question that needs to be resolved.In this work,a phosphoric acid-based deep eutectic solvent(DES)was developed for extracting metals from spent LIBs and one-step selectively separating and efficiently recovering transition metal.The prepared DES shows excellent extraction performance for Li(100%)and Co(92.8%)at 100°C.In addition,the extraction system can effectively separate and precipitate Co through its own components,avoiding the introduction of new precipitants and the destruction of the original composition structure of DES.This also contributes to the good cycle stability of the extraction system with excellent extraction performance for Li(94.3%)and Co(80.8%)after 5 cycles.This work proposes a green method for one-step selectively separating and recovering valuable metals from spent LIBs.展开更多
Bubble–particle interactions are of great importance in cavitation bubble dynamics, especially in the case of silt-laden flow. In this paper,a review of the physical mechanisms involved in bubble collapse near partic...Bubble–particle interactions are of great importance in cavitation bubble dynamics, especially in the case of silt-laden flow. In this paper,a review of the physical mechanisms involved in bubble collapse near particles is presented, with an emphasis on the jet and shock wave phenomenon. First of all, the collapse of a bubble occurring close to a flat wall is introduced to provide a basis for understanding cavitation behavior near boundaries. Then, with the aim of revealing the physical processes that occur during bubble collapse near particles, this is followed by a detailed discussion, with plentiful examples, of the collapse process(the inception, growth, collapse, rebound, and final disappearance of the bubble) and the formation and behavior of jets(the inception jet, counter jet, and double jets) and shock waves(incident,reflected, jet-induced, and jet-split shock waves).展开更多
Augmented reality(AR)displays,heralded as the next-generation platform for spatial computing,metaverse,and digital twins,empower users to perceive digital images overlaid with real-world environment,fostering a deeper...Augmented reality(AR)displays,heralded as the next-generation platform for spatial computing,metaverse,and digital twins,empower users to perceive digital images overlaid with real-world environment,fostering a deeper level of human-digital interactions.With the rapid evolution of couplers,waveguide-based AR displays have streamlined the entire system,boasting a slim form factor and high optical performance.However,challenges persist in the waveguide combiner,including low optical efficiency and poor image uniformity,significantly hindering the long-term usage and user experience.In this paper,we first analyze the root causes of the low optical efficiency and poor uniformity in waveguide-based AR displays.We then discover and elucidate an anomalous polarization conversion phenomenon inherent to polarization volume gratings(PVGs)when the incident light direction does not satisfy the Bragg condition.This new property is effectively leveraged to circumvent the tradeoff between in-coupling efficiency and eyebox uniformity.Through feasibility demonstration experiments,we measure the light leakage in multiple PVGs with varying thicknesses using a laser source and a liquid-crystal-on-silicon light engine.The experiment corroborates the polarization conversion phenomenon,and the results align with simulation well.To explore the potential of such a polarization conversion phenomenon further,we design and simulate a waveguide display with a 50°field of view.Through achieving first-order polarization conversion in a PVG,the in-coupling efficiency and uniformity are improved by 2 times and 2.3 times,respectively,compared to conventional couplers.This groundbreaking discovery holds immense potential for revolutionizing next-generation waveguide-based AR displays,promising a higher efficiency and superior image uniformity.展开更多
Non-native freshwater fish species are regarded as a key factor responsible for the degradation of freshwater ecosystems.Although research on China's non-native freshwater fish species has been conducted at the na...Non-native freshwater fish species are regarded as a key factor responsible for the degradation of freshwater ecosystems.Although research on China's non-native freshwater fish species has been conducted at the national scale,the spatial distribution and introduction pathways of these species in China remain unclear.To address this knowledge gap,this study compiled a dataset of non-native freshwater fish species across administrative regions in China.We first assessed the number of non-native freshwater fish species by taxonomy,geographical origin,introduction pathway,and province.There were 177 non-native freshwater fish species,belonging to 17 orders,48 families,and 118 genera.The orders Cypriniformes(33.3%),Perciformes(28.2%),Siluriformes(10.2%),and Salmoniformes(6.2%)accounted for the largest proportion of non-native freshwater fish species.Eighty-nine nonnative species were introduced from other countries or regions,mostly from North America(31 species;34.8%),Asia(20 species;22.5%),Africa(13 species;14.6%),Europe(11 species;12.4%),and South America(10 species;11.2%).Aquaculture was the most common introduction pathway.Non-native freshwater fish species were more widely distributed in southwest China.Our study showed that there were obvious differences in the number and composition of non-native freshwater fish species across various provinces in China.The variation in the number of non-native freshwater fish species across provinces in China was attributed to distinct geographical features,development of the aquaculture industry,and efforts to study non-native freshwater fish species.Therefore,comprehensive surveys and studies of non-native freshwater fish species are needed,which are of great importance for the management and control of non-native species invasions.展开更多
基金supported by the National Natural Science Foundation of China,No.82271115(to MY).
文摘Synaptic plasticity is essential for maintaining neuronal function in the central nervous system and serves as a critical indicator of the effects of neurodegenerative disease.Glaucoma directly impairs retinal ganglion cells and their axons,leading to axonal transport dysfuntion,subsequently causing secondary damage to anterior or posterior ends of the visual system.Accordingly,recent evidence indicates that glaucoma is a degenerative disease of the central nervous system that causes damage throughout the visual pathway.However,the effects of glaucoma on synaptic plasticity in the primary visual cortex remain unclear.In this study,we established a mouse model of unilateral chronic ocular hypertension by injecting magnetic microbeads into the anterior chamber of one eye.We found that,after 4 weeks of chronic ocular hypertension,the neuronal somas were smaller in the superior colliculus and lateral geniculate body regions of the brain contralateral to the affected eye.This was accompanied by glial cell activation and increased expression of inflammatory factors.After 8 weeks of ocular hypertension,we observed a reduction in the number of excitatory and inhibitory synapses,dendritic spines,and activation of glial cells in the primary visual cortex contralateral to the affected eye.These findings suggest that glaucoma not only directly damages the retina but also induces alterations in synapses and dendritic spines in the primary visual cortex,providing new insights into the pathogenesis of glaucoma.
基金supported by Key Technology Research and Application of Online Control Simulation and Intelligent Decision Making for Active Distribution Network(5108-202218280A-2-377-XG).
文摘Aiming at the problems of increasing uncertainty of low-carbon generation energy in active distribution network(ADN)and the difficulty of security assessment of distribution network,this paper proposes a two-phase scheduling model for flexible resources in ADN based on probabilistic risk perception.First,a full-cycle probabilistic trend sequence is constructed based on the source-load historical data,and in the day-ahead scheduling phase,the response interval of the flexibility resources on the load and storage side is optimized based on the probabilistic trend,with the probability of the security boundary as the security constraint,and with the economy as the objective.Then in the intraday phase,the core security and economic operation boundary of theADNis screened in real time.Fromthere,it quantitatively senses the degree of threat to the core security and economic operation boundary under the current source-load prediction information,and identifies the strictly secure and low/high-risk time periods.Flexibility resources within the response interval are dynamically adjusted in real-time by focusing on high-risk periods to cope with future core risks of the distribution grid.Finally,the improved IEEE 33-node distribution system is simulated to obtain the flexibility resource scheduling scheme on the load and storage side.Thescheduling results are evaluated from the perspectives of risk probability and flexible resource utilization efficiency,and the analysis shows that the scheduling model in this paper can promote the consumption of low-carbon energy from wind and photovoltaic sourceswhile reducing the operational risk of the distribution network.
基金supported by the Australian Research Council Centre of Excellence Project in Optical Microcombs for Breakthrough Science(No.CE230100006)the Australian Research Council Discovery Projects Programs(Nos.P190103186 and FT210100806)+4 种基金Linkage Program(Nos.LP210200345 and LP210100467)the Swinburne ECR-SUPRA program,the Industrial Transformation Training Centres scheme(No.IC180100005)the National Natural Science Foundation of China(No.12404375)the Beijing Natural Science Foundation(No.Z180007)the Innovation Program for Quantum Science and Technology(No.2021ZD0300703).
文摘Optical polarizers,which allow the transmission of specific polarization states,are essential components in modern optical systems.Here,we experimentally demonstrate integrated photonic polarizers incorporating reduced graphene oxide(rGO)films.2D graphene oxide(GO)films are integrated onto silicon waveguides and microring resonators(MRRs)with precise control over their thicknesses and sizes,followed by GO reduction via two different methods including uniform thermal reduction and localized photothermal reduction.We measure devices with various lengths,thicknesses,and reduction degrees of GO films.The results show that the devices with rGO exhibit better performance than those with GO,achieving a polarization-dependent loss of~47 dB and a polarization extinction ratio of~16 dB for the hybrid waveguides and MRRs with rGO,respectively.By fitting the experimental results with theory,it is found that rGO exhibits more significant anisotropy in loss,with an anisotropy ratio over 4 times that of GO.In addition,rGO shows higher thermal stability and greater robustness to photothermal reduction than GO.These results highlight the strong potential of rGO films for implementing high-performance polarization selective devices in integrated photonic platforms.
基金Project supported by the National Key Research and Development Program of China (Grant Nos. 2023YFB3609500 and 2023YFB3609502)the National Natural Science Foundation of China (Grant No. 62274137)+1 种基金the Natural Science Foundation of Jiangxi Province, China (Grant No. 20232BAB202043)the Science and Technology Project of Fujian Province of China (Grant No. 2020I0001)。
文摘A minority carrier lifetime of 25.46 μs in a P-type 4H-SiC epilayer has been attained through sequential thermal oxidation and hydrogen annealing. Thermal oxidation can enhance the minority carrier lifetime in the 4H-SiC epilayer by reducing carbon vacancies. However, this process also generates carbon clusters with limited diffusivity and contributes to the enlargement of surface pits on the 4H-SiC. High-temperature hydrogen annealing effectively reduces stacking fault and dislocation density. Moreover, electron spin resonance analysis indicates a significant reduction in carbon vacancy defects after hydrogen annealing. The mechanisms of the elimination of carbon vacancies by hydrogen annealing include the decomposition of carbon clusters formed during thermal oxidation and the low-pressure selective etching by hydrogen,which increases the carbon content on the 4H-SiC surface and facilitates carbon diffusion. Consequently, the combination of thermal oxidation and hydrogen annealing eliminates carbon vacancies more effectively, substantially enhancing the minority carrier lifetime in P-type 4H-SiC. This improvement is advantageous for the application of high-voltage SiC bipolar devices.
基金supported by grants from the National Key R&D Program of China(2021YFC2400403)the National Natural Science Foundation of China(82201017,51972005)+1 种基金the Young Elite Scientist Sponsorship Program by CAST(2022QNRC001)the China Postdoctoral Science Foundation(2022M710257).
文摘Compared with teenage patients,adult patients generally show a slower rate of tooth movement and more pronounced alveolar bone loss during orthodontic treatment,indicating the maladaptation of alveolar bone homeostasis under orthodontic force.However,this phenomenon is not well-elucidated to date,leading to increased treatment difficulties and unsatisfactory treatment outcomes in adult orthodontics.Aiming to provide a comprehensive knowledge and further inspire insightful understanding towards this issue,this review summarizes the current evidence and underlying mechanisms.The age-related abatements in mechanosensing and mechanotransduction in adult cells and periodontal tissue may contribute to retarded and unbalanced bone metabolism,thus hindering alveolar bone reconstruction during orthodontic treatment.To this end,periodontal surgery,physical and chemical cues are being developed to reactivate or rejuvenate the aging periodontium and restore the dynamic equilibrium of orthodontic-mediated alveolar bone metabolism.We anticipate that this review will present a general overview of the role that aging plays in orthodontic alveolar bone metabolism and shed new light on the prospective ways out of the impasse.
基金This work was financially supported by the University of Michi-gan College of Engineering startup grant and FL and PD acknowl-edge the technical support from the Michigan Center for Materials Characterization(MC^(2)).
文摘Additive manufacturing(AM)has the potential to transform manufacturing by enabling previously un-thinkable products,digital inventory and delivery,and distributed manufacturing.Here we presented an extrusion-based metal AM method(refer to“SoftTouch”depositionin thefiledpatent)thatis suitablefor making the metal feedstock flowable prior to the deposition through dynamic recrystallization induced grain refinement at elevated temperatures.The flowable metal was extruded out of the printer head like a paste for building dense metal parts with fine equiaxed grains and wrought mechanical properties.Off-the-shelf metal rods were used as feedstock and the printing process was completed in an open-air environment,avoiding pricy powders and costly inert or vacuum conditions.The resulting multi-layer de-posited 6061 aluminum alloys yield strength and ductility comparable to wrought 6061 aluminum alloys after the same T6 heat treatment.The extrusion-based metal AM method can also be advanced as green manufacturing technologies for fabricating novel alloys and composites,adding novel features to existing parts,repairing damaged metal parts,and welding advanced metals for supporting sustainable manufac-turing,in addition to being developed into a cost-effective manufacturing process for the fabrication of dense metal of complex structural forms.
基金This study was supported by a grant from the National Natural Science Foundation of China(NSFC,81901040).
文摘As a member of the AFF(AF4/FMR2)family,AFF4 is a transcription elongation factor that is a component of the super elongation complex.AFF4 serves as a scaffolding protein that connects transcription factors and promotes gene transcription through elongation and chromatin remodelling.Here,we investigated the effect of AFF4 on human dental follicle cells(DFCs)in osteogenic differentiation.In this study,we found that small interfering RNA-mediated depletion of AFF4 resulted in decreased alkaline phosphatase(ALP)activity and impaired mineralization.In addition,the expression of osteogenic-related genes(DLX5,SP7,RUNX2 and BGLAP)was significantly downregulated.In contrast,lentivirus-mediated overexpression of AFF4 significantly enhanced the osteogenic potential of human DFCs.Mechanistically,we found that both the mRNA and protein levels of ALKBH1,a critical regulator of epigenetics,changed in accordance with AFF4 expression levels.Overexpression of ALKBH1 in AFF4-depleted DFCs partially rescued the impairment of osteogenic differentiation.Our data indicated that AFF4 promoted the osteogenic differentiation of DFCs by upregulating the transcription of ALKBH1.
基金supported by the National Natural Science Foundation of China(Grant No.62104222)the Natural Science Foundation of Fujian Province of China for Distinguished Young Scholars(Grant No.2020J06002)+3 种基金the Science and Technology Project of Fujian Province of China(Grant No.2020I0001)the Science and Technology Key Projects of Xiamen(Grant No.3502ZCQ20191001)Shenzhen Science and Technology Program(Grant No.JSGG20201102-155800003)Jiangxi Provincial Natural Science Foundation(Grant No.20212ACB212005).
文摘A 4H-SiC trench gate metal-oxide-semiconductor field-effect transistor(UMOSFET)with semi-super-junction shiel-ded structure(SS-UMOS)is proposed and compared with conventional trench MOSFET(CT-UMOS)in this work.The advantage of the proposed structure is given by comprehensive study of the mechanism of the local semi-super-junction structure at the bottom of the trench MOSFET.In particular,the influence of the bias condition of the p-pillar at the bottom of the trench on the static and dynamic performances of the device is compared and revealed.The on-resistance of SS-UMOS with grounded(G)and ungrounded(NG)p-pillar is reduced by 52%(G)and 71%(NG)compared to CT-UMOS,respectively.Additionally,gate ox-ide in the GSS-UMOS is fully protected by the p-shield layer as well as semi-super-junction structure under the trench and p-base regions.Thus,a reduced electric-field of 2 MV/cm can be achieved at the corner of the p-shield layer.However,the quasi-intrinsic protective layer cannot be formed in NGSS-UMOS due to the charge storage effect in the floating p-pillar,resulting in a large electric field of 2.7 MV/cm at the gate oxide layer.Moreover,the total switching loss of GSS-UMOS is 1.95 mJ/cm2 and is reduced by 18%compared with CT-UMOS.On the contrary,the NGSS-UMOS has the slowest overall switching speed due to the weakened shielding effect of the p-pillar and the largest gate-to-drain capacitance among the three.The proposed GSS-UMOS plays an important role in high-voltage and high-frequency applications,and will provide a valuable idea for device design and circuit applications.
基金Project supported by Key Area Research and Development Project of Guangdong Province,China(Grant No.2020B010170002)the Science Challenge Project(Grant No.TZ2018003-1-101)+4 种基金the Natural Science Foundation of Fujian Province of China for Distinguished Young Scholars(Grant No.2020J06002)the Science and Technology Project of Fujian Province of China(Grant No.2020I0001)the Fundamental Research Funds for the Central Universities(Grant Nos.20720190049 and 20720190053)the Science and Technology Key Projects of Xiamen(Grant No.3502ZCQ20191001)the National Natural Science Foundation of China(Grant No.51871189)。
文摘Thermal oxidation and hydrogen annealing were applied on a 100μm thick Al-doped p-type 4H-Si C epitaxial wafer to modulate the minority carrier lifetime,which was investigated by microwave photoconductive decay(μ-PCD).The minority carrier lifetime decreased after each thermal oxidation.On the contrary,with the hydrogen annealing time increasing to3 hours,the minority carrier lifetime increased from 1.1μs(as-grown)to 3.14μs and then saturated after the annealing time reached 4 hours.The increase of surface roughness from 0.236 nm to 0.316 nm may also be one of the reasons for limiting the further improvement of the minority carrier lifetimes.Moreover,the whole wafer mappings of minority carrier lifetimes before and after hydrogen annealing were measured and discussed.The average minority carrier lifetime was up to 1.94μs and non-uniformity of carrier lifetime reached 38%after 4-hour hydrogen annealing.The increasing minority carrier lifetimes could be attributed to the double mechanisms of excess carbon atoms diffusion caused by selective etching of Si atoms and passivation of deep-level defects by hydrogen atoms.
文摘The agricultural scientific research project funding is an important prerequisite for the implementation of agricultural scientific research project,and an essential basic condition to support agricultural research. In recent years,China has paid great attention to the development of scientific research,and increased the input of scientific research funds,but there are some shortcomings in funding management during the implementation of the project. Based on many years of practice,this paper expounds the main problems in the current funding management for agricultural scientific research project,and brings forward the relevant recommendations,in order to provide a reference for the scientific management of agricultural scientific research project funding in the new situation.
基金supported by the National Natural Science Foundation of China(No.82060367)the Science and Technology Plan of Health Commission of Jiangxi Province,China(No.SKJP_220210624)the Science and Technology Research Project of the Department of Education of Jiangxi Province,China(No.GJJ2201455,GJJ211527).
文摘Inter-subtype recombination is the main force for the complexity of HIV-1 genetic diversity,which increases the difficulty of preventing HIV-1 infection and administering antiretroviral therapy for people living with HIV.To date,143 circulating recombinant forms(CRFs)have been re-ported globally,43 of which were identified in China.^(1)Moreover,HIV-1 strains that are produced by second-gen-eration combinations,including unique recombinant forms and CRFs,such as CRF105_0108,CRF123_0107,and CRF134_0185.
文摘Processing emotional and social information are two closely related and evolutionarily conserved fundamental domains that promote survival and health across species[1].However,extensive human neuroimaging studies have yielded inconsistent findings.For instance,the amygdala,a key brain region engaged in social-affective cognition,often lacks differential“activation”during the“emotional vs.neutral faces”contrast[2],[3].
基金supported by the National Natural Science Foundation of China(Project No.51976056).
文摘The dynamic behavior of a cavitation bubble near an asymmetric hydrofoil is investigated experimentally through high-speed photography and theoretically using a Kelvin impulse model.The typical deformations arising during bubble collapse near the hydrofoil are analyzed qualitatively.The effects of the bubble position and the hydrofoil’s eccentricity angle are analyzed quantitatively.The spatial distribution of the Kelvin impulse near the hydrofoil are explored.Different morphological evolutions of a bubble near an asymmetric hydrofoil are revealed,with B-shaped,heart-shaped,and arc-shaped collapses.The velocity of the bubble interface close to the hydrofoil is significantly affected by the bubble-hydrofoil distance and the hydrofoil’s eccentricity angle,increasing as both the distance and the eccentricity angle grow.It is found that the Kelvin impulse sensitivity varies at different positions with respect to the asymmetric hydrofoil,being higher at the head and tail,and lower in the middle.
基金supported by the National Natural Science Foundation of China(Grant No.52336001)the China Postdoctoral Science Foundation(Grant Nos.2022TQ0168,2023M731895)。
文摘The head-flow rate curve with double humps brings greater challenges to the stable operation of a pump-turbine in pump mode,and the present investigation aims to reveal the formation mechanisms behind it.We performed unsteady simulations by applying a modified partially averaged Navier-Stokes(PANS)model and the double hump phenomenon was satisfactorily captured with relative errors within 3.87%by comparing the head with the experimental data.The results showed that the rotating stall occurred in the guide vane during both the first and second hump regions and induced the dominant pressure pulsation component with an oscillating frequency 11.7%times the runner rotation frequency.The reverse flow was observed due to the propagation of rotating stall cells in the guide vane,and the first hump was attributed to the vortex in the vaneless region,with a reduction in the runner's capacity for doing work as the reverse flow reached the blade trailing edge.The second hump was attributed to the flow separation near the leading edge of the runner blades,which extended to the runner outlet and interacted with the rotating stall cell,leading to a rapid extension of the reverse flow into the runner.This not only reduces the runner's capacity for doing work but also significantly increases the energy loss in the blade-to-blade flow passage near the runner exit.This study enhances the understanding of the flow mechanism in the hump region,which can provide insights into the suppression of unstable flows and runner optimization.
基金the financial support for the financial supports from the National Natural Science Foundation of China(grant Nos.21908082,22278426,21878133,and 22178154)the Natural Science Foundation of Jiangsu Province(BK20190854)+1 种基金Jiangsu Funding Program for Excellent Postdoctoral Talent(2022ZB629)the China Postdoctoral Science Foundation(2021M701472)
文摘With more and more lithium-ion batteries(LIBs)being put into production and application,precious metals such as lithium and cobalt are scarce,so it is imminent to recover various strategic metal resources from spent LIBs.Meanwhile,the complex and difficult problem of separating and recovering metals from leaching solutions has been an urgent question that needs to be resolved.In this work,a phosphoric acid-based deep eutectic solvent(DES)was developed for extracting metals from spent LIBs and one-step selectively separating and efficiently recovering transition metal.The prepared DES shows excellent extraction performance for Li(100%)and Co(92.8%)at 100°C.In addition,the extraction system can effectively separate and precipitate Co through its own components,avoiding the introduction of new precipitants and the destruction of the original composition structure of DES.This also contributes to the good cycle stability of the extraction system with excellent extraction performance for Li(94.3%)and Co(80.8%)after 5 cycles.This work proposes a green method for one-step selectively separating and recovering valuable metals from spent LIBs.
基金financially supported by the National Natural Science Foundation of China (Project No. 51976056)
文摘Bubble–particle interactions are of great importance in cavitation bubble dynamics, especially in the case of silt-laden flow. In this paper,a review of the physical mechanisms involved in bubble collapse near particles is presented, with an emphasis on the jet and shock wave phenomenon. First of all, the collapse of a bubble occurring close to a flat wall is introduced to provide a basis for understanding cavitation behavior near boundaries. Then, with the aim of revealing the physical processes that occur during bubble collapse near particles, this is followed by a detailed discussion, with plentiful examples, of the collapse process(the inception, growth, collapse, rebound, and final disappearance of the bubble) and the formation and behavior of jets(the inception jet, counter jet, and double jets) and shock waves(incident,reflected, jet-induced, and jet-split shock waves).
文摘Augmented reality(AR)displays,heralded as the next-generation platform for spatial computing,metaverse,and digital twins,empower users to perceive digital images overlaid with real-world environment,fostering a deeper level of human-digital interactions.With the rapid evolution of couplers,waveguide-based AR displays have streamlined the entire system,boasting a slim form factor and high optical performance.However,challenges persist in the waveguide combiner,including low optical efficiency and poor image uniformity,significantly hindering the long-term usage and user experience.In this paper,we first analyze the root causes of the low optical efficiency and poor uniformity in waveguide-based AR displays.We then discover and elucidate an anomalous polarization conversion phenomenon inherent to polarization volume gratings(PVGs)when the incident light direction does not satisfy the Bragg condition.This new property is effectively leveraged to circumvent the tradeoff between in-coupling efficiency and eyebox uniformity.Through feasibility demonstration experiments,we measure the light leakage in multiple PVGs with varying thicknesses using a laser source and a liquid-crystal-on-silicon light engine.The experiment corroborates the polarization conversion phenomenon,and the results align with simulation well.To explore the potential of such a polarization conversion phenomenon further,we design and simulate a waveguide display with a 50°field of view.Through achieving first-order polarization conversion in a PVG,the in-coupling efficiency and uniformity are improved by 2 times and 2.3 times,respectively,compared to conventional couplers.This groundbreaking discovery holds immense potential for revolutionizing next-generation waveguide-based AR displays,promising a higher efficiency and superior image uniformity.
基金supported by the Key R&D Program of Jiangxi Province(Grant No.2023BBG70011)Key R&D Program of Jiangxi Province(Grant No.20203BBG72W007)+2 种基金Knowledge Innovation Program of Wuhan-Basic Research(Grant No.2022020801010141)the Jiangxi Province Finance Special-2023 Annual Comprehensive Support Projects for Intensifying the Battle for Clean Water(JXAEPS2023-001)supported by the research funding of Laboratory of Ecological Security and Biodiversity Conservation of Cities on the Yangtze River Delta,Shanghai Science and Technology Museum.
文摘Non-native freshwater fish species are regarded as a key factor responsible for the degradation of freshwater ecosystems.Although research on China's non-native freshwater fish species has been conducted at the national scale,the spatial distribution and introduction pathways of these species in China remain unclear.To address this knowledge gap,this study compiled a dataset of non-native freshwater fish species across administrative regions in China.We first assessed the number of non-native freshwater fish species by taxonomy,geographical origin,introduction pathway,and province.There were 177 non-native freshwater fish species,belonging to 17 orders,48 families,and 118 genera.The orders Cypriniformes(33.3%),Perciformes(28.2%),Siluriformes(10.2%),and Salmoniformes(6.2%)accounted for the largest proportion of non-native freshwater fish species.Eighty-nine nonnative species were introduced from other countries or regions,mostly from North America(31 species;34.8%),Asia(20 species;22.5%),Africa(13 species;14.6%),Europe(11 species;12.4%),and South America(10 species;11.2%).Aquaculture was the most common introduction pathway.Non-native freshwater fish species were more widely distributed in southwest China.Our study showed that there were obvious differences in the number and composition of non-native freshwater fish species across various provinces in China.The variation in the number of non-native freshwater fish species across provinces in China was attributed to distinct geographical features,development of the aquaculture industry,and efforts to study non-native freshwater fish species.Therefore,comprehensive surveys and studies of non-native freshwater fish species are needed,which are of great importance for the management and control of non-native species invasions.
