A systematic study of the aperture efficiency and mode constituent for orbital angular momentum(OAM) vortex beam generated by digital metasurface is presented. The aperture efficiency and OAM spectrum are computed for...A systematic study of the aperture efficiency and mode constituent for orbital angular momentum(OAM) vortex beam generated by digital metasurface is presented. The aperture efficiency and OAM spectrum are computed for different bit numbers. It is found that the aperture efficiency declines for digital metasurface due to the phase quantization error,especially for 1-bit device. Fortunately, the OAM spectrum is barely affected by phase quantization and the designated main mode keeps dominant for different bit numbers, indicating that high purity OAM vortex beam can be generated by digital metasurface. Besides, the influence of topological charge l is also investigated. For a fixed metasurface, the radiation performance deteriorates sharply with the growing of l and the parasitic OAM mode becomes dominant at certain angle.At last, a prototype of 1-bit metasurface was simulated, fabricated and measured in anechoic chamber. The simulation and experiment results verify the correctness of the numerical analysis.展开更多
Reinforced concrete (RC) shield building as the first external defense layer of AP1000 structure plays an important role in protection the population and environment when against the outer explosion. The strain rate e...Reinforced concrete (RC) shield building as the first external defense layer of AP1000 structure plays an important role in protection the population and environment when against the outer explosion. The strain rate effect of reinforced concrete was taken into consideration in the establishment of an AP1000 nuclear island structure-air-explosives fully coupled model by using the software AUTODYN. Object using damage mass as index, to infer the degree of damage. This paper studied the pressure evolution and damage mechanism. The analysis results provide valuable data on improving the anti-explosion capabilities in design based on the damage characteristics.展开更多
Background:Cerebrovascular disease(CVD)ranks among the foremost factors responsible for mortality on a global scale.The mortality patterns of CVDs and temporal trends in China need to be well-illustrated and updated.M...Background:Cerebrovascular disease(CVD)ranks among the foremost factors responsible for mortality on a global scale.The mortality patterns of CVDs and temporal trends in China need to be well-illustrated and updated.Methods:We collected mortality data on patients with CVD from Chinese Center for Disease Control and Prevention’s Disease Surveillance Points(CDC-DSP)system.The mortality of CVD in 2020 was described by age,sex,residence,and region.The temporal trend from 2013 to 2019 was evaluated using joinpoint regression,and estimated rates of decline were extrapolated until 2030 using time series models.Results:In 2019,the age-standardized mortality in China(ASMRC)per 100,000 individuals was 113.2.The ASMRC for males(137.7/10^(5))and rural areas(123.0/10^(5))were both higher when stratified by gender and urban/rural residence.The central region had the highest mortality(126.5/10^(5)),the western region had a slightly lower mortality(123.5/10^(5)),and the eastern region had the lowest mortality(97.3/10^(5)).The age-specific mortality showed an accelerated upward trend from aged 55-59 years,with maximum mortality observed in individuals over 85 years of age.The age-standardized mortality of CVD decreased by 2.43%(95%confidence interval,1.02-3.81%)annually from 2013 to 2019.Notably,the age-specific mortality of CVD increased from 2013 to 2019 for the age group of over 85 years.In 2020,both the absolute number of CVD cases and the crude mortality of CVD have increased compared to their values in 2019.The estimated total deaths due to CVD were estimated to reach 2.3 million in 2025 and 2.4 million in 2030.Conclusion:The heightened focus on the burden of CVD among males,rural areas,the central and western of China,and individuals aged 75 years and above has emerged as a pivotal determinant in further decreasing mortalities,consequently presenting novel challenges to strategies for disease prevention and control.展开更多
A new series of medical antibacterial high-entropy alloys(HEAs)with composition Ti 50 Zr 25 Nb 20 Cu 5-x Ag x(x=0 at.%,1 at.%,and 2.5 at.%)were developed by arc-melting the mixture of pure elements under a high-purity...A new series of medical antibacterial high-entropy alloys(HEAs)with composition Ti 50 Zr 25 Nb 20 Cu 5-x Ag x(x=0 at.%,1 at.%,and 2.5 at.%)were developed by arc-melting the mixture of pure elements under a high-purity argon atmosphere.The cytotoxicity,osteo-conductivity,and antibacterial properties of these HEAs were systematically investigated in vitro,along with their in vivo biocompatibility and antibacte-rial properties.These HEAs,especially Ti_(50)Zr_(25)Nb_(20)Cu_(2.5)Ag_(2.5),showed better antibacterial ability against Staphylococcus aureus than Ti-6Al-4V,which has a nearly 99%antibacterial rate in vitro.Moreover,ion release and cytotoxicity tests showed that these HEAs had excellent biosafety,similar to or better than that of Ti-6Al-4V.Osteoblasts were used to evaluate the osteogenic activity of these HEAs,and good osteo-conductivity was observed in vitro.In a Sprague-Dawley rat infection model,Ti_(50)Zr_(25)Nb_(20)Cu_(2.5)Ag_(2.5)showed remarkable antibacterial properties compared to Ti-6Al-4V.The in vivo biocompatibility results showed that Ti_(50)Zr_(25)Nb_(20)Cu_(2.5)Ag_(2.5)did not increase biotoxicity compared to Ti-6Al-4V.The excellent bio-compatibility and antibacterial properties of the Ti-Zr-Nb-Cu-Ag HEAs are expected to enable the pre-vention of periprosthetic/peri-implant infections in the future.展开更多
Various mechanisms underlie causative large artery occlusion(LAO)in patients with acute ischaemic stroke.Cardioembolic and atherosclerotic occlusions are the two most common types.The pathophysiological changes and re...Various mechanisms underlie causative large artery occlusion(LAO)in patients with acute ischaemic stroke.Cardioembolic and atherosclerotic occlusions are the two most common types.The pathophysiological changes and responses to mechanical thrombectomy(MT)and antithrombotic treatments including thrombolysis,antiplatelet and anticoagulation therapy may vary among patients with different aetiological mechanisms of occlusion.Atherosclerotic occlusion is inclined to have relatively abundant collaterals and larger area of penumbra,hence a relatively wider time window for reperfusion therapy,while poor response to medical thrombolysis and MT.Severe residual stenosis and reocclusion occurred frequently after MT in atherosclerotic LAO.Angioplasty and stenting as rescue or the first-line therapy and more intensified antiplatelet therapy beyond related recommendations in the current guidelines are sometimes used in managing acute causative LAO because of poor recanalisation after recommended standard thrombolysis or MT therapy,which are usually based on individual experience.Standard protocol to establish emergent aetiological diagnosis of causative LAO and individualised aetiology-specific treatment strategy is needed.展开更多
An ultrawideband,polarization-insensitive,metamaterial absorber for oblique angle of incidence is presented using characteristic mode analysis.The absorber consists of conductive meander square loops and symmetric ben...An ultrawideband,polarization-insensitive,metamaterial absorber for oblique angle of incidence is presented using characteristic mode analysis.The absorber consists of conductive meander square loops and symmetric bent metallic strips,which are embedded with lumped resistors.With the aid of modal currents and modal weighting coefficients,the positions of the lumped resistors are determined.After that,the equivalent circuit(EC)model and admittance formula are proposed and analyzed to further understand the working principle and ultrawide bandwidth.The proposed absorber measures an absorption bandwidth of 4.3–26.5 GHz(144.1%in fractional bandwidth)for 90%absorptivity under normal incidence.At the oblique angle of incidence of 45°,the bandwidth of 90%absorptivity is still 5.1–21.3 GHz(122.72%)for transverse electric(TE)polarization,and 6.8–29.5 GHz(125.07%)for transverse magnetic(TM)polarization.The good agreement among simulation,measurement,and EC calculation demonstrates the validity of the proposed method and indicates that the method can be applied to other microwave and optical frequency bands.The proposed metamaterial absorber can be widely applied in electromagnetic compatibility,electromagnetic interference,radar stealth,and biomedical detection.展开更多
This research was conducted to develop an effective approach to sort off-ground harvested almonds for efficient drying based on their physical and aerodynamic properties.Three popular varieties were studied,including ...This research was conducted to develop an effective approach to sort off-ground harvested almonds for efficient drying based on their physical and aerodynamic properties.Three popular varieties were studied,including Nonpareil,Monterey,and Fritz.The insect damage,axial dimensions,weight ratio,moisture content,bulk density and terminal velocity of in-hull almonds,in-shell almonds and loose hull at harvest were measured.The results indicated that the insect infestation percentage in the off-ground harvested almonds ranged from 2.5%to 6.3%,which was about half of those in the conventional on-ground dried almonds.Loose hulls and in-hull almonds had higher moisture content and wider moisture distribution than those of in-shell almonds,suggesting that sorting of the almonds and drying them separately are necessary for efficient handling and processing.Thickness was the smallest axial dimension of an almond,and thus could be used for sorting.The cut-off sizes of 16.5 mm,21.3 mm and 21.1 mm could separate 100%of the in-shell almonds from the rest for Nonpareil,Monterey and Fritz varieties,respectively,as the first step.In the second step,applying terminal velocities of 12.3 m/s,11.8 m/s and 12.2 m/s could efficiently separate the in-hull almonds and loose hulls for Nonpareil,Monterey and Fritz varieties,respectively.Overall,up to 76.7%of the loose hulls could be removed,and up to 3.3%in-hull almonds may be lost during the sorting process.The experimental results provided important information for developing efficient sorting and drying methods with improved throughput,energy efficiency,better quality and safety of off-ground harvested almonds.展开更多
文摘A systematic study of the aperture efficiency and mode constituent for orbital angular momentum(OAM) vortex beam generated by digital metasurface is presented. The aperture efficiency and OAM spectrum are computed for different bit numbers. It is found that the aperture efficiency declines for digital metasurface due to the phase quantization error,especially for 1-bit device. Fortunately, the OAM spectrum is barely affected by phase quantization and the designated main mode keeps dominant for different bit numbers, indicating that high purity OAM vortex beam can be generated by digital metasurface. Besides, the influence of topological charge l is also investigated. For a fixed metasurface, the radiation performance deteriorates sharply with the growing of l and the parasitic OAM mode becomes dominant at certain angle.At last, a prototype of 1-bit metasurface was simulated, fabricated and measured in anechoic chamber. The simulation and experiment results verify the correctness of the numerical analysis.
文摘Reinforced concrete (RC) shield building as the first external defense layer of AP1000 structure plays an important role in protection the population and environment when against the outer explosion. The strain rate effect of reinforced concrete was taken into consideration in the establishment of an AP1000 nuclear island structure-air-explosives fully coupled model by using the software AUTODYN. Object using damage mass as index, to infer the degree of damage. This paper studied the pressure evolution and damage mechanism. The analysis results provide valuable data on improving the anti-explosion capabilities in design based on the damage characteristics.
文摘Background:Cerebrovascular disease(CVD)ranks among the foremost factors responsible for mortality on a global scale.The mortality patterns of CVDs and temporal trends in China need to be well-illustrated and updated.Methods:We collected mortality data on patients with CVD from Chinese Center for Disease Control and Prevention’s Disease Surveillance Points(CDC-DSP)system.The mortality of CVD in 2020 was described by age,sex,residence,and region.The temporal trend from 2013 to 2019 was evaluated using joinpoint regression,and estimated rates of decline were extrapolated until 2030 using time series models.Results:In 2019,the age-standardized mortality in China(ASMRC)per 100,000 individuals was 113.2.The ASMRC for males(137.7/10^(5))and rural areas(123.0/10^(5))were both higher when stratified by gender and urban/rural residence.The central region had the highest mortality(126.5/10^(5)),the western region had a slightly lower mortality(123.5/10^(5)),and the eastern region had the lowest mortality(97.3/10^(5)).The age-specific mortality showed an accelerated upward trend from aged 55-59 years,with maximum mortality observed in individuals over 85 years of age.The age-standardized mortality of CVD decreased by 2.43%(95%confidence interval,1.02-3.81%)annually from 2013 to 2019.Notably,the age-specific mortality of CVD increased from 2013 to 2019 for the age group of over 85 years.In 2020,both the absolute number of CVD cases and the crude mortality of CVD have increased compared to their values in 2019.The estimated total deaths due to CVD were estimated to reach 2.3 million in 2025 and 2.4 million in 2030.Conclusion:The heightened focus on the burden of CVD among males,rural areas,the central and western of China,and individuals aged 75 years and above has emerged as a pivotal determinant in further decreasing mortalities,consequently presenting novel challenges to strategies for disease prevention and control.
基金supported by the Beijing Xicheng Sci-ence,Technology and Informatization bureau(No.XCSTS-SD2018-693)and by Beijing Municipal Science and Technology Commission(No.Z181100001918028).
文摘A new series of medical antibacterial high-entropy alloys(HEAs)with composition Ti 50 Zr 25 Nb 20 Cu 5-x Ag x(x=0 at.%,1 at.%,and 2.5 at.%)were developed by arc-melting the mixture of pure elements under a high-purity argon atmosphere.The cytotoxicity,osteo-conductivity,and antibacterial properties of these HEAs were systematically investigated in vitro,along with their in vivo biocompatibility and antibacte-rial properties.These HEAs,especially Ti_(50)Zr_(25)Nb_(20)Cu_(2.5)Ag_(2.5),showed better antibacterial ability against Staphylococcus aureus than Ti-6Al-4V,which has a nearly 99%antibacterial rate in vitro.Moreover,ion release and cytotoxicity tests showed that these HEAs had excellent biosafety,similar to or better than that of Ti-6Al-4V.Osteoblasts were used to evaluate the osteogenic activity of these HEAs,and good osteo-conductivity was observed in vitro.In a Sprague-Dawley rat infection model,Ti_(50)Zr_(25)Nb_(20)Cu_(2.5)Ag_(2.5)showed remarkable antibacterial properties compared to Ti-6Al-4V.The in vivo biocompatibility results showed that Ti_(50)Zr_(25)Nb_(20)Cu_(2.5)Ag_(2.5)did not increase biotoxicity compared to Ti-6Al-4V.The excellent bio-compatibility and antibacterial properties of the Ti-Zr-Nb-Cu-Ag HEAs are expected to enable the pre-vention of periprosthetic/peri-implant infections in the future.
基金This article was founded by the Hainan Provincial Committee of Health and Family Planning.Grant No.1423320.54A1006.
文摘Various mechanisms underlie causative large artery occlusion(LAO)in patients with acute ischaemic stroke.Cardioembolic and atherosclerotic occlusions are the two most common types.The pathophysiological changes and responses to mechanical thrombectomy(MT)and antithrombotic treatments including thrombolysis,antiplatelet and anticoagulation therapy may vary among patients with different aetiological mechanisms of occlusion.Atherosclerotic occlusion is inclined to have relatively abundant collaterals and larger area of penumbra,hence a relatively wider time window for reperfusion therapy,while poor response to medical thrombolysis and MT.Severe residual stenosis and reocclusion occurred frequently after MT in atherosclerotic LAO.Angioplasty and stenting as rescue or the first-line therapy and more intensified antiplatelet therapy beyond related recommendations in the current guidelines are sometimes used in managing acute causative LAO because of poor recanalisation after recommended standard thrombolysis or MT therapy,which are usually based on individual experience.Standard protocol to establish emergent aetiological diagnosis of causative LAO and individualised aetiology-specific treatment strategy is needed.
基金National Natural Science Foundation of China(62171460)Natural Science Basic Research Program of Shaanxi Province(2022JM-319,2022JQ-685,20210110,20200108,20220104,2020022)。
文摘An ultrawideband,polarization-insensitive,metamaterial absorber for oblique angle of incidence is presented using characteristic mode analysis.The absorber consists of conductive meander square loops and symmetric bent metallic strips,which are embedded with lumped resistors.With the aid of modal currents and modal weighting coefficients,the positions of the lumped resistors are determined.After that,the equivalent circuit(EC)model and admittance formula are proposed and analyzed to further understand the working principle and ultrawide bandwidth.The proposed absorber measures an absorption bandwidth of 4.3–26.5 GHz(144.1%in fractional bandwidth)for 90%absorptivity under normal incidence.At the oblique angle of incidence of 45°,the bandwidth of 90%absorptivity is still 5.1–21.3 GHz(122.72%)for transverse electric(TE)polarization,and 6.8–29.5 GHz(125.07%)for transverse magnetic(TM)polarization.The good agreement among simulation,measurement,and EC calculation demonstrates the validity of the proposed method and indicates that the method can be applied to other microwave and optical frequency bands.The proposed metamaterial absorber can be widely applied in electromagnetic compatibility,electromagnetic interference,radar stealth,and biomedical detection.
文摘This research was conducted to develop an effective approach to sort off-ground harvested almonds for efficient drying based on their physical and aerodynamic properties.Three popular varieties were studied,including Nonpareil,Monterey,and Fritz.The insect damage,axial dimensions,weight ratio,moisture content,bulk density and terminal velocity of in-hull almonds,in-shell almonds and loose hull at harvest were measured.The results indicated that the insect infestation percentage in the off-ground harvested almonds ranged from 2.5%to 6.3%,which was about half of those in the conventional on-ground dried almonds.Loose hulls and in-hull almonds had higher moisture content and wider moisture distribution than those of in-shell almonds,suggesting that sorting of the almonds and drying them separately are necessary for efficient handling and processing.Thickness was the smallest axial dimension of an almond,and thus could be used for sorting.The cut-off sizes of 16.5 mm,21.3 mm and 21.1 mm could separate 100%of the in-shell almonds from the rest for Nonpareil,Monterey and Fritz varieties,respectively,as the first step.In the second step,applying terminal velocities of 12.3 m/s,11.8 m/s and 12.2 m/s could efficiently separate the in-hull almonds and loose hulls for Nonpareil,Monterey and Fritz varieties,respectively.Overall,up to 76.7%of the loose hulls could be removed,and up to 3.3%in-hull almonds may be lost during the sorting process.The experimental results provided important information for developing efficient sorting and drying methods with improved throughput,energy efficiency,better quality and safety of off-ground harvested almonds.
