Compared with traditional piezoelectric ultrasonic devices,optoacoustic devices have unique advantages such as a simple preparation process,anti-electromagnetic interference,and wireless long-distance power supply.How...Compared with traditional piezoelectric ultrasonic devices,optoacoustic devices have unique advantages such as a simple preparation process,anti-electromagnetic interference,and wireless long-distance power supply.However,current optoacoustic devices remain limited due to a low damage threshold and energy conversion efficiency,which seriously hinder their widespread applications.In this study,using a self-healing polydimethylsiloxane(PDMS,Fe-Hpdca-PDMS)and carbon nanotube composite,a flexible optoacoustic patch is developed,which possesses the self-healing capability at room temperature,and can even recover from damage induced by cutting or laser irradiation.Moreover,this patch can generate high-intensity ultrasound(>25 MPa)without the focusing structure.The laser damage threshold is greater than 183.44 mJ cm^(-2),and the optoacoustic energy conversion efficiency reaches a major achievement at 10.66×10^(-3),compared with other carbon-based nanomaterials and PDMS composites.This patch is also been successfully examined in the application of acoustic flow,thrombolysis,and wireless energy harvesting.All findings in this study provides new insight into designing and fabricating of novel ultrasound devices for biomedical applications.展开更多
Geomagnetic storm events have a strong influence on the ionosphere–thermosphere(I-T)coupling system.Analyzing the regional response process of the I-T system and its differences across the northern and southern hemis...Geomagnetic storm events have a strong influence on the ionosphere–thermosphere(I-T)coupling system.Analyzing the regional response process of the I-T system and its differences across the northern and southern hemispheres is an important but challenging task.In this study,we used a combination of multiple observations and a model simulation to examine the north–south hemispheric difference in the I-T coupling system in the American and Asian sectors during the geomagnetic superstorm that occurred in May 2024.Observations of the total electron content(TEC)showed that the Asian sector had negative storms in the northern hemisphere and positive storms in the southern hemisphere,a process that exacerbated the hemispheric differences in the TEC.However,both hemispheres of the American sector showed negative storms.The thermospheric composition changes also differed between the two sectors,and their variation could partially explain the hemispheric differences caused by positive and negative storms.Moreover,the influence of the thermospheric density change was less than that of the thermospheric composition.Finally,the dynamic effect of the thermospheric wind and the plasma transport processes strongly modulated the north–south differences in the TEC at nighttime in the American and Asian sectors,respectively,during this superstorm.展开更多
Lead-based organic-inorganic hybrid perovskites have exhibited great potential in photovoltaics,achieving power conversion efficiencies(PCEs) exceeding 25%.However,the toxicity of lead and the instability of these mat...Lead-based organic-inorganic hybrid perovskites have exhibited great potential in photovoltaics,achieving power conversion efficiencies(PCEs) exceeding 25%.However,the toxicity of lead and the instability of these materials under moist conditions pose significant barriers to large-scale production.To overcome these limitations,researchers have proposed mixed-valence double perovskites,where Cs_(2)Au~ⅠAu~ⅢI_6 is a particularly effective absorber due to its suitable band gap and high absorptance efficiency.To further extend the scope of these lead-free materials,we varied the trivalent gold ion and halogen anion in Cs_(2)Au~ⅠAu~ⅢI_6,resulting in 18 new structures with unique properties.Further,using first-principles calculations and elimination criteria,we identified four materials with ideal band gaps,small effective carrier mass,and strong anisotropic optical properties.According to theoretical modeling,Cs_(2)AuSbCl_6,Cs_(2)AuInCl_6,and Cs_(2)AuBiCl_6 are potential candidates for solar cell absorbers,with a spectroscopic limited maximum efficiency(SLME) of approximately 30% in a 0.25 μm-thick film.These three compounds have not been previously reported,and therefore,our work provides new insights into potential materials for solar energy conversion.We aim for this theoretical exploration of novel perovskites to guide future experiments and accelerate the development of high-performance photovoltaic devices.展开更多
Green hydrogen produced by water electrolysis combined with renewable energy is a promising alternative to fossil fuels due to its high energy density with zero-carbon emissions.Among water electrolysis technologies,t...Green hydrogen produced by water electrolysis combined with renewable energy is a promising alternative to fossil fuels due to its high energy density with zero-carbon emissions.Among water electrolysis technologies,the anion exchange membrane(AEM) water electrolysis has gained intensive attention and is considered as the next-generation emerging technology due to its potential advantages,such as the use of low-cost non-noble metal catalysts,the relatively mature stack assembly process,etc.However,the AEM water electrolyzer is still in the early development stage of the kW-level stack,which is mainly attributed to severe performance decay caused by the core component,i.e.,AEM.Here,the review comprehensively presents the recent progress of advanced AEM from the view of the performance of water electrolysis cells.Herein,fundamental principles and critical components of AEM water electrolyzers are introduced,and work conditions of AEM water electrolyzers and AEM performance improvement strategies are discussed.The challenges and perspectives are also analyzed.展开更多
Dear Editor, This letter deals with the problem of algorithm recommendation for online fault detection of spacecraft. By transforming the time series data into distributions and introducing a distribution-aware measur...Dear Editor, This letter deals with the problem of algorithm recommendation for online fault detection of spacecraft. By transforming the time series data into distributions and introducing a distribution-aware measure, a principal method is designed for quantifying the detectabilities of fault detection algorithms over special datasets.展开更多
Metal-catalyzed alkene arylalkoxylation is a powerful complexity-building strategy for the synthesis of oxygen heterocycles from simpleγ-unsaturated alcohols,but only a few examples of catalytic enantioselective meth...Metal-catalyzed alkene arylalkoxylation is a powerful complexity-building strategy for the synthesis of oxygen heterocycles from simpleγ-unsaturated alcohols,but only a few examples of catalytic enantioselective methods exist.Herein,an efficient palladium-catalyzed enantioselective arylalkoxylation ofγ-hydroxyalkenes with aryl halides is reported.The salient features of this transformation include a remarkable broad substrate scope,mild reaction conditions,and good functional group tolerance,delivering a series of chiral tetrahydrofurans containing a tertiary or quaternary stereocenter in good yields with up to 95%ee.The Xu10 ligand with a suitable side-arm was responsible for the high reactivity and good enantioselectivity of this transformation.展开更多
Limited cells and factors,inadequate mechanical properties,and necrosis of defects center have hindered the wide clinical application of bone-tissue engineering scaffolds.Herein,we construct a self-oxygenated 3D print...Limited cells and factors,inadequate mechanical properties,and necrosis of defects center have hindered the wide clinical application of bone-tissue engineering scaffolds.Herein,we construct a self-oxygenated 3D printed bioactive hydrogel scaffold by integrating oxygen-generating nanoparticles and hybrid double network hydrogel structure.The hydrogel scaffold possesses the characteristics of extracellular matrix;Meanwhile,the fabricated hybrid double network structure by polyacrylamide and CaCl2-crosslinked sodium carboxymethylcellulose endows the hydrogel favorable compressive strength and 3D printability.Furthermore,the O2 generated by CaO2 nanoparticles encapsulated in ZIF-8 releases steadily and sustainably because of the well-developed microporous structure of ZIF-8,which can significantly promote cell viability and proliferation in vitro,as well as angiogenesis and osteogenic differentiation with the assistance of Zn2+.More significantly,the synergy of O2 and 3D printed pore structure can prevent necrosis of defects center and facilitate cell infiltration by providing cells the nutrients and space they need,which can further induce vascular network ingrowth and accelerate bone regeneration in all areas of the defect in vivo.Overall,this work provides a new avenue for preparing cell/factor-free bone-tissue engineered scaffolds that possess great potential for tissue regeneration and clinical alternative.展开更多
The genesis of the giant Dongshengmiao in the northern margin of the North China Block has been debated since its discovery in the 1950 s,because it shows geological and geochemical characteristics with both syngeneti...The genesis of the giant Dongshengmiao in the northern margin of the North China Block has been debated since its discovery in the 1950 s,because it shows geological and geochemical characteristics with both syngenetic and epigenetic signatures.It has geological settings and sulfur and lead isotopic compositions that are similar with typical SEDEX(sedimentary exhalative) deposit,while the Zn-Pb-Cu mineralization was controlled by shear deformation and metamorphism,showing similarities with orogenic-type deposits.In this contribution,both the syngenetic and epigenetic features of the Dongshengmiao are envisaged,and accounted for in the context of a genetic model with two metallogenic periods.Massive pyrite at the Dongshengmiao was mostly recrystallized during metamorphism,but finegrained texture was locally preserved,indicating its syngenetic origin.On the contrary,all the Zn-Pb-Cu ores observed in this study show characteristics of epigenetic hydrothermal mineralization that controlled by metamorphism and accompanying shear deformation.The sulfur and lead isotopic compositions of sphalerite and galena indicate that they were in situ remobilized from a syngenetic stratabound source,and the oxygen and hydrogen isotopic ratios of ore-fluid indicate that the large-scale remobilization was assisted by metamorphic fluid.The thermodynamic modeling indicates that the orefluid during remobilization has a great potential of transporting Cu.This may account for the abnormally enriched Cu in the remobilized SEDEX deposit.The metamorphic fluid might strip Cu from the fluid source during devolatilization,and overprint it on the Zn-Pb orebodies during remobilization.A secondary flowthrough modeling reveals that Zn- and Cu-sulfides would be preferentially redistributed in Fe-rich carbonates during remobilization,as a result of fluid-rock interaction.Conclusively,a multistage genetic model is proposed.During the development of the Proterozoic rift,stratabound Zn-Pb mineralization took place in a SEDEX ore-forming system.The syngenetic sulfides subsequently underwent a large-scale fluidassisted remobilization during the early Cretaceous metamorphism and thrusting,forming the shear zone-controlled epigenetic orebodies.During the remobilization process,Cu was scavenged from the source of metamorphic fluid,and deposited accompanying remobilized Zn-Pb sulfides.Shear structures and Fe-rich carbonates are ideal sites for redistribution and re-deposition of remobilized sulfide.展开更多
BACKGROUND: Vascular endothelial cell apoptosis participates in cerebral ischemia/reperfusion injury, and the method of Qi-supplementation and blood-activation has remarkable neuroprotective effects against cerebral ...BACKGROUND: Vascular endothelial cell apoptosis participates in cerebral ischemia/reperfusion injury, and the method of Qi-supplementation and blood-activation has remarkable neuroprotective effects against cerebral ischemia/reperfusion injury. OBJECTIVE: To explore the molecular mechanism that Dingnaofang (Chinese herbs for supplementing Qi and activating blood circulation) inhibits vascular endothelial cell apoptosis induced by cerebral ischemia/reperfusion injury. DESIGN, TIME AND SETFING: A randomized controlled animal experiment was performed at the Department of Central Laboratory, Third Xiangya Hospital, Central South University, China, between October 2007 and December 2008. MATERIALS: Dingnaofang consisted of Huangqi (Milkvetch Root; Radix Astragah), Chuanxiong (Szechwan Lovage Rhizome; Rhizoma Chuanxiong), Yinxingye (ginkgo leaf; Fofium Ginkgo), Dilong (earthworm; Pheretima), Danggui (Chinese Angelica; Radix Angelicae Sinensis), Tianqi (Radix Notoginseng), and Gancao (Radix Glycyrrhizae; Radix Glycytthizae), with a proportion of 5:2:2: 1: 1: 1: 1. METHODS: A total of 130 Sprague Dawley rats were randomly divided into sham-surgery (n = 10), cerebral ischemia/reperfusion (n = 40), cerebral ischemia pretreatment (n = 40) and Dingnaofang pretreatment groups (n = 40). Middle cerebral artery occlusion was used to induce cerebral ischemic injury. The bilateral common carotid artery in the cerebral ischemia pretreatment group was blocked for 10 minutes on days 7, 3 and 1 prior to ischemia/reperfusion injury, while rats in Dingnaofang pretreatment group were intragastrically administrated with 4 g Dingnaofang 1 week prior to cerebral ischemia once per day, for 7 successive days. MAIN OUTCOME MEASURES: Apoptosis ratios in vascular endothelial cells were measured using Hoechst 33258 staining and flow cytometry; apoptosis was detected by monitoring DNA gradient bands and the activation of caspase-3, 8, 9 and Bid using Western blot. RESULTS: Following cerebral ischemiaJreperfusion injury, the number of apoptotic vascular endothelial cells in the middle cerebral artery significantly increased (P 〈 0.01); however, cerebral ischemia pretreatment and Dingnaofang pretreatment groups significantly reduced apoptosis induced by cerebral ischemia/reperfusion injury (P 〈 0.01). In particular, DNA gradient bands were not observed following Dingnaofang pretreatment. At 24 hours after cerebral ischemia/reperfusion injury, cleaved fragments of caspase-3, 8 and 9 were detected at 11 kD (P 11), 20 kD (P 20) and 10 kD (P 10), respectively, following Western blot. Bid was also cleaved into its truncated form (tBid; 15 kD). Gray scale analysis indicated that P 11, P 20, P 10 and tBid band values in the Dingnaofang pretreatment group were significantly less than in the cerebral ischemia/reperfusion and cerebral ischemia pretreatment groups (P 〈 0.01 or P 〈 0.05). CONCLUSION: Dingnaofang inhibits vascular endothelial cell apoptosis induced by cerebral ischemia/reperfusion injury via inhibition of apoptotic signal transduction pathways.展开更多
Heat dissipation is an important part of light-emitting diode(LED)filament research and has aroused constant concern.In this paper,we studied the thermal performance of flexible LED filament by numerical simulation an...Heat dissipation is an important part of light-emitting diode(LED)filament research and has aroused constant concern.In this paper,we studied the thermal performance of flexible LED filament by numerical simulation and through experiment.The heat dissipation characteristics of spring-like structure flexible LED filament were computed by finite volume method,and it was found that the chip junction temperature was closely related to the pitch and the bending radius.The effect of inclination angle of lighting LED filament was discussed because it is relevant to the spring-like structure flexible LED filament in geometry.The results demonstrated that the temperature of the filament increases as the inclination angle improves.展开更多
This paper assesses the evolution of generation technology-mix in Australia,with specific emphasis on understanding how such evolution has been shaped by wider political and socioeconomic influences.This assessment is...This paper assesses the evolution of generation technology-mix in Australia,with specific emphasis on understanding how such evolution has been shaped by wider political and socioeconomic influences.This assessment is predicated on the argument that the contemporary,quintessentially techno-economic,policy discourse on renewable energy is deficient,as it ignores climacteric political and socio-economic influences on generation technology-mix.The methodological framework employed in this paper is informed by the core tenets of technological change theory.The assessment suggests that generation technology-mix in Australia has historically been overwhelmingly influenced by the underlying technological paradigm of the electricity industry;and that this technological paradigm essentially draws its imprimatur from the wider political and socio-economic contexts.By implication,it suggests that a rapid uptake of renewables will have widespread ramifications,extending into political,socio-economic and cultural realms of a society.Clearly,existing policy discourse-that tends to focus on technical potentials,cost competitiveness,externalities and risks of various renewable technologies-is deficient.A much broader discourse is needed.This paper also made an attempt to develop a basis for such a discourse by reviewing broader aspects of the Australian society that would be affected by a rapid uptake of renewables.展开更多
Based on the problems of traditional living environment of the Tibetan Gongbu culture and the concept of inheriting the Tibetan Gongbu culture and the harmonious coexistence of environment and human,living environment...Based on the problems of traditional living environment of the Tibetan Gongbu culture and the concept of inheriting the Tibetan Gongbu culture and the harmonious coexistence of environment and human,living environment design of Juemu Village on the side of the Niyang River is optimized. It adheres to the importance of traditional culture,and especially emphasizes the layout of buildings with Tibetan style and their surrounding,function optimization,and the plant design,thereby exploring and attempting planning method of Tibetan living environment under the background of new rural construction.展开更多
Background:Botulinum toxin type A injection,a noninvasive alternative method for treating masseteric hypertrophy,is inadequate for treating patients with a round lower face.This study aimed to investigate the operativ...Background:Botulinum toxin type A injection,a noninvasive alternative method for treating masseteric hypertrophy,is inadequate for treating patients with a round lower face.This study aimed to investigate the operative technique and clinical results of liposuction followed by botulinum toxin type A injections in patients with masseteric hypertrophy and excessive subcutaneous fat.Methods:Sixty-five patients(50 women and 15 men)were treated using this technique between May 2014 and January 2019.Their mean age was 26.3 years(range,18–35 years)and the mean follow-up period was 13 months(range,8–18 months).Results:All patients achieved slimmer lower cheeks with improved jaw definitions after the procedure.Among the 65 patients,61(94%)expressed satisfaction with the results and believed that the procedure produced their desired face shape.No major complications were observed.The effect of this combination treatment remained stable for 12 months after the procedure.Conclusion:The authors believe that liposuction followed by botulinum toxin type A injections is an effective technique for the treatment of masseteric hypertrophy and excessive subcutaneous fat.It is also a relatively simple and safe treatment approach.展开更多
Cation-disordered rocksalt oxides(DRX)have been identified as promising cathode materials for high energy density applications owing to their variable elemental composition and cationic-anionic redox activity.However,...Cation-disordered rocksalt oxides(DRX)have been identified as promising cathode materials for high energy density applications owing to their variable elemental composition and cationic-anionic redox activity.However,their practical implementation has been impeded by unwanted phenomena such as irrepressible transition metal migration/dissolution and O_(2)/CO_(2)evolution,which arise due to parasitic reactions and densification-degradation mechanisms during extended cycling.To address these issues,a micron-sized DRX cathode Li_(1.2)Ni_(1/3)Ti_(1/3)W_(2/15)O_(1.85)F_(0.15)(SLNTWOF)with F substitution and ultrathin LiF coating layer is developed by alcohols assisted sol-gel method.Within this fluorination-induced integrated structure design(FISD)strategy,in-situ F substitution modifies the activity/reversibility of the cationic-anionic redox reaction,while the ultrathin LiF coating and single-crystal structure synergistically mitigate the cathode/electrolyte parasitic reaction and densification-degradation mechanism.Attributed to the multiple modifications and size effect in the FISD strategy,the SLNTWOF sample exhibits reversible cationic-anionic redox chemistry with a meliorated reversible capacity of 290.3 mA h g^(-1)at 0.05C(1C=200 mA g^(-1)),improved cycling stability of 78.5%capacity retention after 50 cycles at 0.5 C,and modified rate capability of 102.8 mA h g^(-1)at 2 C.This work reveals that the synergistic effects between bulk structure modification,surface regulation,and engineering particle size can effectively modulate the distribution and evolution of cationic-anionic redox activities in DRX cathodes.展开更多
Infrared target detection models are more required than ever before to be deployed on embedded platforms,which requires models with less memory consumption and better real-time performance while considering accuracy.T...Infrared target detection models are more required than ever before to be deployed on embedded platforms,which requires models with less memory consumption and better real-time performance while considering accuracy.To address the above challenges,we propose a modified You Only Look Once(YOLO)algorithm PF-YOLOv4-Tiny.The algorithm incorpo-rates spatial pyramidal pooling(SPP)and squeeze-and-excitation(SE)visual attention modules to enhance the target localization capability.The PANet-based-feature pyramid networks(P-FPN)are proposed to transfer semantic information and location information simultaneously to ameliorate detection accuracy.To lighten the network,the standard convolutions other than the backbone network are replaced with depthwise separable convolutions.In post-processing the images,the soft-non-maximum suppression(soft-NMS)algorithm is employed to subside the missed and false detection problems caused by the occlusion between targets.The accuracy of our model can finally reach 61.75%,while the total Params is only 9.3 M and GFLOPs is 11.At the same time,the inference speed reaches 87 FPS on NVIDIA GeForce GTX 1650 Ti,which can meet the requirements of the infrared target detection algorithm for the embedded deployments.展开更多
Due to the complexity and faintness of the detection wave patterns obtained by aircoupled transducers,if it is possible to effectively separate the various modes and obtain nondispersive signals for more accurate dete...Due to the complexity and faintness of the detection wave patterns obtained by aircoupled transducers,if it is possible to effectively separate the various modes and obtain nondispersive signals for more accurate detection and positioning,it will help to improve the accuracy and reliability of air-coupled ultrasonic Lamb wave detection,providing better technical support for the application and development of related fields.Because of the increased complexity of aircoupled signals,there is no definite theoretical formula to describe the mode changes of aircoupled signals,so the method based on blind separation has unique value.To address these challenges,the paper proposes a single-channel blind source separation(SCBSS)method.The effectiveness of this method is evaluated through simulations and experiments,demonstrating favorable separation results and efficient computational speed.This work first conducts an in-depth analysis of the signal characteristics of air-coupled ultrasonic non-destructive testing,and simulates the ultrasonic excitation conditions of air-coupled sensors through finite element software.The study of modal changes and multipath effects caused by the variation of the incidence angle of the ACT signal is carried out,and the situation of the Lamb wave signal excited by ACT at the receiving end is analyzed.By combining ACT with PZT signals,the ultrasonic signals of air-coupled Lamb waves are compared and studied,and their modal purification is carried out.展开更多
Recently,Meta AI Research approaches a general,promptable segment anything model(SAM)pre-trained on an unprecedentedly large segmentation dataset(SA-1B).Without a doubt,the emergence of SAM will yield significant bene...Recently,Meta AI Research approaches a general,promptable segment anything model(SAM)pre-trained on an unprecedentedly large segmentation dataset(SA-1B).Without a doubt,the emergence of SAM will yield significant benefits for a wide array of practical image segmentation applications.In this study,we conduct a series of intriguing investigations into the performance of SAM across various applications,particularly in the fields of natural images,agriculture,manufacturing,remote sensing and healthcare.We analyze and discuss the benefits and limitations of SAM,while also presenting an outlook on its future development in segmentation tasks.By doing so,we aim to give a comprehensive understanding of SAM's practical applications.This work is expected to provide insights that facilitate future research activities toward generic segmentation.Source code is publicly available at https://github.com/LiuTingWed/SAM-Not-Perfect.展开更多
1 Introduction With the advancement of sensing,machine learning,and computing systems,automated driving applications have been growing rapidly worldwide.Together with the devel-opment of communication technologies suc...1 Introduction With the advancement of sensing,machine learning,and computing systems,automated driving applications have been growing rapidly worldwide.Together with the devel-opment of communication technologies such as dedicated short-range communication,extensively emerging intelli-gent vehicles have been developed to connect with vehicles,pedestrians,infrastructures,and clouds in the transportation network.Thus,intelligent vehicles have become intelligent mobile terminal that carries rich functions and services.展开更多
基金This work was supported by the Natural Science Foundation of China(Grant no.U22A20259,12102140)the Shenzhen Basic Science Research(No.JCYJ20200109110006136)the China Postdoctoral Science Foundation(No.2022M721258).We also thank the Analytical and Testing Center of Huazhong University of Science&Technology.
文摘Compared with traditional piezoelectric ultrasonic devices,optoacoustic devices have unique advantages such as a simple preparation process,anti-electromagnetic interference,and wireless long-distance power supply.However,current optoacoustic devices remain limited due to a low damage threshold and energy conversion efficiency,which seriously hinder their widespread applications.In this study,using a self-healing polydimethylsiloxane(PDMS,Fe-Hpdca-PDMS)and carbon nanotube composite,a flexible optoacoustic patch is developed,which possesses the self-healing capability at room temperature,and can even recover from damage induced by cutting or laser irradiation.Moreover,this patch can generate high-intensity ultrasound(>25 MPa)without the focusing structure.The laser damage threshold is greater than 183.44 mJ cm^(-2),and the optoacoustic energy conversion efficiency reaches a major achievement at 10.66×10^(-3),compared with other carbon-based nanomaterials and PDMS composites.This patch is also been successfully examined in the application of acoustic flow,thrombolysis,and wireless energy harvesting.All findings in this study provides new insight into designing and fabricating of novel ultrasound devices for biomedical applications.
基金supported by the National Natural Science Foundation of China (Grant Nos. 42030202, 42241115, and 42174204)the China Postdoctoral Science Foundation (Grant No. 2023M743467)+2 种基金the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant No. Y202021)the National Key R&D Program of China (Grant No. 2022YFF0504400)the Opening Funding of the Chinese Academy of Sciences dedicated to the Chinese Meridian Project
文摘Geomagnetic storm events have a strong influence on the ionosphere–thermosphere(I-T)coupling system.Analyzing the regional response process of the I-T system and its differences across the northern and southern hemispheres is an important but challenging task.In this study,we used a combination of multiple observations and a model simulation to examine the north–south hemispheric difference in the I-T coupling system in the American and Asian sectors during the geomagnetic superstorm that occurred in May 2024.Observations of the total electron content(TEC)showed that the Asian sector had negative storms in the northern hemisphere and positive storms in the southern hemisphere,a process that exacerbated the hemispheric differences in the TEC.However,both hemispheres of the American sector showed negative storms.The thermospheric composition changes also differed between the two sectors,and their variation could partially explain the hemispheric differences caused by positive and negative storms.Moreover,the influence of the thermospheric density change was less than that of the thermospheric composition.Finally,the dynamic effect of the thermospheric wind and the plasma transport processes strongly modulated the north–south differences in the TEC at nighttime in the American and Asian sectors,respectively,during this superstorm.
基金the National Natural Science Foundation of China (22175180, 21975260)。
文摘Lead-based organic-inorganic hybrid perovskites have exhibited great potential in photovoltaics,achieving power conversion efficiencies(PCEs) exceeding 25%.However,the toxicity of lead and the instability of these materials under moist conditions pose significant barriers to large-scale production.To overcome these limitations,researchers have proposed mixed-valence double perovskites,where Cs_(2)Au~ⅠAu~ⅢI_6 is a particularly effective absorber due to its suitable band gap and high absorptance efficiency.To further extend the scope of these lead-free materials,we varied the trivalent gold ion and halogen anion in Cs_(2)Au~ⅠAu~ⅢI_6,resulting in 18 new structures with unique properties.Further,using first-principles calculations and elimination criteria,we identified four materials with ideal band gaps,small effective carrier mass,and strong anisotropic optical properties.According to theoretical modeling,Cs_(2)AuSbCl_6,Cs_(2)AuInCl_6,and Cs_(2)AuBiCl_6 are potential candidates for solar cell absorbers,with a spectroscopic limited maximum efficiency(SLME) of approximately 30% in a 0.25 μm-thick film.These three compounds have not been previously reported,and therefore,our work provides new insights into potential materials for solar energy conversion.We aim for this theoretical exploration of novel perovskites to guide future experiments and accelerate the development of high-performance photovoltaic devices.
基金supported by the National Key Research and Development Program(2022YFB4202200)the Fundamental Research Funds for the Central Universities and sponsored by Shanghai Pujiang Program(22PJ1413100)。
文摘Green hydrogen produced by water electrolysis combined with renewable energy is a promising alternative to fossil fuels due to its high energy density with zero-carbon emissions.Among water electrolysis technologies,the anion exchange membrane(AEM) water electrolysis has gained intensive attention and is considered as the next-generation emerging technology due to its potential advantages,such as the use of low-cost non-noble metal catalysts,the relatively mature stack assembly process,etc.However,the AEM water electrolyzer is still in the early development stage of the kW-level stack,which is mainly attributed to severe performance decay caused by the core component,i.e.,AEM.Here,the review comprehensively presents the recent progress of advanced AEM from the view of the performance of water electrolysis cells.Herein,fundamental principles and critical components of AEM water electrolyzers are introduced,and work conditions of AEM water electrolyzers and AEM performance improvement strategies are discussed.The challenges and perspectives are also analyzed.
基金supported by the National Key R&D Program of China (2021YFB1715000)the National Natural Science Foundation of China (U1811461, 62022013, 12150007, 62103450, 61832003, 62272137)。
文摘Dear Editor, This letter deals with the problem of algorithm recommendation for online fault detection of spacecraft. By transforming the time series data into distributions and introducing a distribution-aware measure, a principal method is designed for quantifying the detectabilities of fault detection algorithms over special datasets.
基金funding support of the National Natural Science Foundation of China(NSFC,Nos.22071060 and 22031004)the National Key R&D Program of China(No.2021YFF0701600)Shanghai Municipal Education Commission(No.20212308)。
文摘Metal-catalyzed alkene arylalkoxylation is a powerful complexity-building strategy for the synthesis of oxygen heterocycles from simpleγ-unsaturated alcohols,but only a few examples of catalytic enantioselective methods exist.Herein,an efficient palladium-catalyzed enantioselective arylalkoxylation ofγ-hydroxyalkenes with aryl halides is reported.The salient features of this transformation include a remarkable broad substrate scope,mild reaction conditions,and good functional group tolerance,delivering a series of chiral tetrahydrofurans containing a tertiary or quaternary stereocenter in good yields with up to 95%ee.The Xu10 ligand with a suitable side-arm was responsible for the high reactivity and good enantioselectivity of this transformation.
基金supported by the National Natural Science Foundation of China(NSFC,22172082)NCC Fund(NCC2020FH05)+1 种基金Fundamental Research Funds for the Central Universities,Natural Science Foundation of Tianjin Municipal Science and Technology Commission(2022KJ208)Tianjin Health Science and Technology Project(TJWJ2021QN041).
文摘Limited cells and factors,inadequate mechanical properties,and necrosis of defects center have hindered the wide clinical application of bone-tissue engineering scaffolds.Herein,we construct a self-oxygenated 3D printed bioactive hydrogel scaffold by integrating oxygen-generating nanoparticles and hybrid double network hydrogel structure.The hydrogel scaffold possesses the characteristics of extracellular matrix;Meanwhile,the fabricated hybrid double network structure by polyacrylamide and CaCl2-crosslinked sodium carboxymethylcellulose endows the hydrogel favorable compressive strength and 3D printability.Furthermore,the O2 generated by CaO2 nanoparticles encapsulated in ZIF-8 releases steadily and sustainably because of the well-developed microporous structure of ZIF-8,which can significantly promote cell viability and proliferation in vitro,as well as angiogenesis and osteogenic differentiation with the assistance of Zn2+.More significantly,the synergy of O2 and 3D printed pore structure can prevent necrosis of defects center and facilitate cell infiltration by providing cells the nutrients and space they need,which can further induce vascular network ingrowth and accelerate bone regeneration in all areas of the defect in vivo.Overall,this work provides a new avenue for preparing cell/factor-free bone-tissue engineered scaffolds that possess great potential for tissue regeneration and clinical alternative.
基金financially supported by the National Basic Research Program of the People's Republic of China(Nos.2013CB429801,2006CB403500)the National Natural Science Foundation of China(Nos.40972057,41502069)the Postdoctoral Science Foundation of China(No.2015M570033)
文摘The genesis of the giant Dongshengmiao in the northern margin of the North China Block has been debated since its discovery in the 1950 s,because it shows geological and geochemical characteristics with both syngenetic and epigenetic signatures.It has geological settings and sulfur and lead isotopic compositions that are similar with typical SEDEX(sedimentary exhalative) deposit,while the Zn-Pb-Cu mineralization was controlled by shear deformation and metamorphism,showing similarities with orogenic-type deposits.In this contribution,both the syngenetic and epigenetic features of the Dongshengmiao are envisaged,and accounted for in the context of a genetic model with two metallogenic periods.Massive pyrite at the Dongshengmiao was mostly recrystallized during metamorphism,but finegrained texture was locally preserved,indicating its syngenetic origin.On the contrary,all the Zn-Pb-Cu ores observed in this study show characteristics of epigenetic hydrothermal mineralization that controlled by metamorphism and accompanying shear deformation.The sulfur and lead isotopic compositions of sphalerite and galena indicate that they were in situ remobilized from a syngenetic stratabound source,and the oxygen and hydrogen isotopic ratios of ore-fluid indicate that the large-scale remobilization was assisted by metamorphic fluid.The thermodynamic modeling indicates that the orefluid during remobilization has a great potential of transporting Cu.This may account for the abnormally enriched Cu in the remobilized SEDEX deposit.The metamorphic fluid might strip Cu from the fluid source during devolatilization,and overprint it on the Zn-Pb orebodies during remobilization.A secondary flowthrough modeling reveals that Zn- and Cu-sulfides would be preferentially redistributed in Fe-rich carbonates during remobilization,as a result of fluid-rock interaction.Conclusively,a multistage genetic model is proposed.During the development of the Proterozoic rift,stratabound Zn-Pb mineralization took place in a SEDEX ore-forming system.The syngenetic sulfides subsequently underwent a large-scale fluidassisted remobilization during the early Cretaceous metamorphism and thrusting,forming the shear zone-controlled epigenetic orebodies.During the remobilization process,Cu was scavenged from the source of metamorphic fluid,and deposited accompanying remobilized Zn-Pb sulfides.Shear structures and Fe-rich carbonates are ideal sites for redistribution and re-deposition of remobilized sulfide.
基金the National Natural Science Foundation of China,No. 30672035Scientific and Technological Foundation of Traditional Chinese Medicine of Public Health Bureau of Hunan Province,No. 620230
文摘BACKGROUND: Vascular endothelial cell apoptosis participates in cerebral ischemia/reperfusion injury, and the method of Qi-supplementation and blood-activation has remarkable neuroprotective effects against cerebral ischemia/reperfusion injury. OBJECTIVE: To explore the molecular mechanism that Dingnaofang (Chinese herbs for supplementing Qi and activating blood circulation) inhibits vascular endothelial cell apoptosis induced by cerebral ischemia/reperfusion injury. DESIGN, TIME AND SETFING: A randomized controlled animal experiment was performed at the Department of Central Laboratory, Third Xiangya Hospital, Central South University, China, between October 2007 and December 2008. MATERIALS: Dingnaofang consisted of Huangqi (Milkvetch Root; Radix Astragah), Chuanxiong (Szechwan Lovage Rhizome; Rhizoma Chuanxiong), Yinxingye (ginkgo leaf; Fofium Ginkgo), Dilong (earthworm; Pheretima), Danggui (Chinese Angelica; Radix Angelicae Sinensis), Tianqi (Radix Notoginseng), and Gancao (Radix Glycyrrhizae; Radix Glycytthizae), with a proportion of 5:2:2: 1: 1: 1: 1. METHODS: A total of 130 Sprague Dawley rats were randomly divided into sham-surgery (n = 10), cerebral ischemia/reperfusion (n = 40), cerebral ischemia pretreatment (n = 40) and Dingnaofang pretreatment groups (n = 40). Middle cerebral artery occlusion was used to induce cerebral ischemic injury. The bilateral common carotid artery in the cerebral ischemia pretreatment group was blocked for 10 minutes on days 7, 3 and 1 prior to ischemia/reperfusion injury, while rats in Dingnaofang pretreatment group were intragastrically administrated with 4 g Dingnaofang 1 week prior to cerebral ischemia once per day, for 7 successive days. MAIN OUTCOME MEASURES: Apoptosis ratios in vascular endothelial cells were measured using Hoechst 33258 staining and flow cytometry; apoptosis was detected by monitoring DNA gradient bands and the activation of caspase-3, 8, 9 and Bid using Western blot. RESULTS: Following cerebral ischemiaJreperfusion injury, the number of apoptotic vascular endothelial cells in the middle cerebral artery significantly increased (P 〈 0.01); however, cerebral ischemia pretreatment and Dingnaofang pretreatment groups significantly reduced apoptosis induced by cerebral ischemia/reperfusion injury (P 〈 0.01). In particular, DNA gradient bands were not observed following Dingnaofang pretreatment. At 24 hours after cerebral ischemia/reperfusion injury, cleaved fragments of caspase-3, 8 and 9 were detected at 11 kD (P 11), 20 kD (P 20) and 10 kD (P 10), respectively, following Western blot. Bid was also cleaved into its truncated form (tBid; 15 kD). Gray scale analysis indicated that P 11, P 20, P 10 and tBid band values in the Dingnaofang pretreatment group were significantly less than in the cerebral ischemia/reperfusion and cerebral ischemia pretreatment groups (P 〈 0.01 or P 〈 0.05). CONCLUSION: Dingnaofang inhibits vascular endothelial cell apoptosis induced by cerebral ischemia/reperfusion injury via inhibition of apoptotic signal transduction pathways.
基金Project supported by the National Natural Science Foundation of China(Grant No.51302171)Science and Technology Commission of Shanghai Municipality,China(Grant No.14500503300)+2 种基金Shanghai Municipal Alliance Program,China(Grant No.Lm201547)Shanghai Cooperative Project,China(Grant No.ShanghaiCXY-2013-61)Jiashan County Technology Program,China(Grant No.20141316)
文摘Heat dissipation is an important part of light-emitting diode(LED)filament research and has aroused constant concern.In this paper,we studied the thermal performance of flexible LED filament by numerical simulation and through experiment.The heat dissipation characteristics of spring-like structure flexible LED filament were computed by finite volume method,and it was found that the chip junction temperature was closely related to the pitch and the bending radius.The effect of inclination angle of lighting LED filament was discussed because it is relevant to the spring-like structure flexible LED filament in geometry.The results demonstrated that the temperature of the filament increases as the inclination angle improves.
文摘This paper assesses the evolution of generation technology-mix in Australia,with specific emphasis on understanding how such evolution has been shaped by wider political and socioeconomic influences.This assessment is predicated on the argument that the contemporary,quintessentially techno-economic,policy discourse on renewable energy is deficient,as it ignores climacteric political and socio-economic influences on generation technology-mix.The methodological framework employed in this paper is informed by the core tenets of technological change theory.The assessment suggests that generation technology-mix in Australia has historically been overwhelmingly influenced by the underlying technological paradigm of the electricity industry;and that this technological paradigm essentially draws its imprimatur from the wider political and socio-economic contexts.By implication,it suggests that a rapid uptake of renewables will have widespread ramifications,extending into political,socio-economic and cultural realms of a society.Clearly,existing policy discourse-that tends to focus on technical potentials,cost competitiveness,externalities and risks of various renewable technologies-is deficient.A much broader discourse is needed.This paper also made an attempt to develop a basis for such a discourse by reviewing broader aspects of the Australian society that would be affected by a rapid uptake of renewables.
基金Supported by Higher Vocational Education Quality Promotion Plan of 2016(Education Quality Improvement Plan of Higher Vocational College of Garden Technology)Humanities and Social Sciences Research Projects in Tibet Colleges and Universities(sk2015-36)Innovative Entrepreneurship Training Program for Undergraduate at Autonomous Region Level in 2015(Riverfront Landscape Design of Niyang River Scenery Belt)
文摘Based on the problems of traditional living environment of the Tibetan Gongbu culture and the concept of inheriting the Tibetan Gongbu culture and the harmonious coexistence of environment and human,living environment design of Juemu Village on the side of the Niyang River is optimized. It adheres to the importance of traditional culture,and especially emphasizes the layout of buildings with Tibetan style and their surrounding,function optimization,and the plant design,thereby exploring and attempting planning method of Tibetan living environment under the background of new rural construction.
基金the National Natural Science Foundation of China(grant no.81671964,2017/01–2020/12).
文摘Background:Botulinum toxin type A injection,a noninvasive alternative method for treating masseteric hypertrophy,is inadequate for treating patients with a round lower face.This study aimed to investigate the operative technique and clinical results of liposuction followed by botulinum toxin type A injections in patients with masseteric hypertrophy and excessive subcutaneous fat.Methods:Sixty-five patients(50 women and 15 men)were treated using this technique between May 2014 and January 2019.Their mean age was 26.3 years(range,18–35 years)and the mean follow-up period was 13 months(range,8–18 months).Results:All patients achieved slimmer lower cheeks with improved jaw definitions after the procedure.Among the 65 patients,61(94%)expressed satisfaction with the results and believed that the procedure produced their desired face shape.No major complications were observed.The effect of this combination treatment remained stable for 12 months after the procedure.Conclusion:The authors believe that liposuction followed by botulinum toxin type A injections is an effective technique for the treatment of masseteric hypertrophy and excessive subcutaneous fat.It is also a relatively simple and safe treatment approach.
基金supported by the National Key R&D Program of China(2021YFB2401800)the National Natural Science Foundation of China(22179008,21875022)+2 种基金the Natural Science Foundation of Chongqing,China(cstc2020jcyj-msxmX0589,cstc2020jcyjmsxmX0654)the support from Beijing Institute of Technology Research Fund Program for Young Scholarsthe 4B7B beamlines radiation equipment of Beijing Synchrotron Radiation Facility(2021-BEPC-PT-005924,2021-BEPC-PT-005967)。
文摘Cation-disordered rocksalt oxides(DRX)have been identified as promising cathode materials for high energy density applications owing to their variable elemental composition and cationic-anionic redox activity.However,their practical implementation has been impeded by unwanted phenomena such as irrepressible transition metal migration/dissolution and O_(2)/CO_(2)evolution,which arise due to parasitic reactions and densification-degradation mechanisms during extended cycling.To address these issues,a micron-sized DRX cathode Li_(1.2)Ni_(1/3)Ti_(1/3)W_(2/15)O_(1.85)F_(0.15)(SLNTWOF)with F substitution and ultrathin LiF coating layer is developed by alcohols assisted sol-gel method.Within this fluorination-induced integrated structure design(FISD)strategy,in-situ F substitution modifies the activity/reversibility of the cationic-anionic redox reaction,while the ultrathin LiF coating and single-crystal structure synergistically mitigate the cathode/electrolyte parasitic reaction and densification-degradation mechanism.Attributed to the multiple modifications and size effect in the FISD strategy,the SLNTWOF sample exhibits reversible cationic-anionic redox chemistry with a meliorated reversible capacity of 290.3 mA h g^(-1)at 0.05C(1C=200 mA g^(-1)),improved cycling stability of 78.5%capacity retention after 50 cycles at 0.5 C,and modified rate capability of 102.8 mA h g^(-1)at 2 C.This work reveals that the synergistic effects between bulk structure modification,surface regulation,and engineering particle size can effectively modulate the distribution and evolution of cationic-anionic redox activities in DRX cathodes.
基金supported by The Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grants No.19JKB520031).
文摘Infrared target detection models are more required than ever before to be deployed on embedded platforms,which requires models with less memory consumption and better real-time performance while considering accuracy.To address the above challenges,we propose a modified You Only Look Once(YOLO)algorithm PF-YOLOv4-Tiny.The algorithm incorpo-rates spatial pyramidal pooling(SPP)and squeeze-and-excitation(SE)visual attention modules to enhance the target localization capability.The PANet-based-feature pyramid networks(P-FPN)are proposed to transfer semantic information and location information simultaneously to ameliorate detection accuracy.To lighten the network,the standard convolutions other than the backbone network are replaced with depthwise separable convolutions.In post-processing the images,the soft-non-maximum suppression(soft-NMS)algorithm is employed to subside the missed and false detection problems caused by the occlusion between targets.The accuracy of our model can finally reach 61.75%,while the total Params is only 9.3 M and GFLOPs is 11.At the same time,the inference speed reaches 87 FPS on NVIDIA GeForce GTX 1650 Ti,which can meet the requirements of the infrared target detection algorithm for the embedded deployments.
基金Supported by the National Natural Science Foundation of China(Nos.92360306,52222504 and 52241502).
文摘Due to the complexity and faintness of the detection wave patterns obtained by aircoupled transducers,if it is possible to effectively separate the various modes and obtain nondispersive signals for more accurate detection and positioning,it will help to improve the accuracy and reliability of air-coupled ultrasonic Lamb wave detection,providing better technical support for the application and development of related fields.Because of the increased complexity of aircoupled signals,there is no definite theoretical formula to describe the mode changes of aircoupled signals,so the method based on blind separation has unique value.To address these challenges,the paper proposes a single-channel blind source separation(SCBSS)method.The effectiveness of this method is evaluated through simulations and experiments,demonstrating favorable separation results and efficient computational speed.This work first conducts an in-depth analysis of the signal characteristics of air-coupled ultrasonic non-destructive testing,and simulates the ultrasonic excitation conditions of air-coupled sensors through finite element software.The study of modal changes and multipath effects caused by the variation of the incidence angle of the ACT signal is carried out,and the situation of the Lamb wave signal excited by ACT at the receiving end is analyzed.By combining ACT with PZT signals,the ultrasonic signals of air-coupled Lamb waves are compared and studied,and their modal purification is carried out.
基金supported by the Mitacs,CFI-JELF and NSERC Discovery grants.
文摘Recently,Meta AI Research approaches a general,promptable segment anything model(SAM)pre-trained on an unprecedentedly large segmentation dataset(SA-1B).Without a doubt,the emergence of SAM will yield significant benefits for a wide array of practical image segmentation applications.In this study,we conduct a series of intriguing investigations into the performance of SAM across various applications,particularly in the fields of natural images,agriculture,manufacturing,remote sensing and healthcare.We analyze and discuss the benefits and limitations of SAM,while also presenting an outlook on its future development in segmentation tasks.By doing so,we aim to give a comprehensive understanding of SAM's practical applications.This work is expected to provide insights that facilitate future research activities toward generic segmentation.Source code is publicly available at https://github.com/LiuTingWed/SAM-Not-Perfect.
文摘1 Introduction With the advancement of sensing,machine learning,and computing systems,automated driving applications have been growing rapidly worldwide.Together with the devel-opment of communication technologies such as dedicated short-range communication,extensively emerging intelli-gent vehicles have been developed to connect with vehicles,pedestrians,infrastructures,and clouds in the transportation network.Thus,intelligent vehicles have become intelligent mobile terminal that carries rich functions and services.