This study investigates the influences of urban land cover on the extreme rainfall event over the Zhengzhou city in central China on 20 July 2021 using the Weather Research and Forecasting model at a convection-permit...This study investigates the influences of urban land cover on the extreme rainfall event over the Zhengzhou city in central China on 20 July 2021 using the Weather Research and Forecasting model at a convection-permitting scale[1-km resolution in the innermost domain(d3)].Two ensembles of simulation(CTRL,NURB),each consisting of 11 members with a multi-layer urban canopy model and various combinations of physics schemes,were conducted using different land cover scenarios:(i)the real urban land cover,(ii)all cities in d3 being replaced with natural land cover.The results suggest that CTRL reasonably reproduces the spatiotemporal evolution of rainstorms and the 24-h rainfall accumulation over the key region,although the maximum hourly rainfall is underestimated and displaced to the west or southwest by most members.The ensemble mean 24-h rainfall accumulation over the key region of heavy rainfall is reduced by 13%,and the maximum hourly rainfall simulated by each member is reduced by 15–70 mm in CTRL relative to NURB.The reduction in the simulated rainfall by urbanization is closely associated with numerous cities/towns to the south,southeast,and east of Zhengzhou.Their heating effects jointly lead to formation of anomalous upward motions in and above the planetary boundary layer(PBL),which exaggerates the PBL drying effect due to reduced evapotranspiration and also enhances the wind stilling effect due to increased surface friction in urban areas.As a result,the lateral inflows of moisture and high-θe(equivalent potential temperature)air from south and east to Zhengzhou are reduced.展开更多
A mesoscale convective system(MCS)is an organized cluster of thunderstorms known to be the most important convective mode in causing disastrous high-impact weather,such as heavy rainfall,hail,damaging winds,and tornad...A mesoscale convective system(MCS)is an organized cluster of thunderstorms known to be the most important convective mode in causing disastrous high-impact weather,such as heavy rainfall,hail,damaging winds,and tornadoes.The small spatial scale and fast temporal evolution of MCSs make their observation and prediction very challenging.East Asia is home to the world’s most prominent monsoon,setting the stage for various severe convective weather events.MCSs and their associated high-impact weather have long been critical issues of concern;as such,their research efforts are valued by governments in East Asia.展开更多
Liquid crystal elastomers are active materials that combine the anisotropic properties of liquid crystals with the elasticity of polymer networks.The LCEs exhibit remarkable reversible contraction and elongation capab...Liquid crystal elastomers are active materials that combine the anisotropic properties of liquid crystals with the elasticity of polymer networks.The LCEs exhibit remarkable reversible contraction and elongation capabilities in response to external stimuli,rendering them highly promising for diverse applications,such as soft robotics,haptic devices,shape morphing structures,etc,However,the predominant reliance on heating as the driving stimulus for LCEs has limited their practical applications.This drawback can be effectively addressed by incorporating fllers,which can generate heat under various stimuli.The recent progress in LCE composites has significantly expanded the application potential of LCEs.In this minireview,we present the design strategies for soft actuators with LCE composites,followed by a detailed exploration of photothermal and electrothermal LCE.composites as prominent examples.Furthermore,we provide an outlook on the challenges and opportunities in the feld of LCE composites.展开更多
In this study,the unprecedented extreme rainfall event during 19-20 July 2021,which caused devastating flooding in Zhengzhou City and its nearby areas,is examined based on observational data analysis and WRF model 40-...In this study,the unprecedented extreme rainfall event during 19-20 July 2021,which caused devastating flooding in Zhengzhou City and its nearby areas,is examined based on observational data analysis and WRF model 40-h simulations on 1-km horizontal resolution.The results show that the model successfully reproduces(i)major synopticscale weather systems(i.e.,the western Pacific subtropical high,the Tibetan high,two typhoons,and the Huang-Huai cyclone),(ii)convective initiation along the east to north edge of the Songshan Mountain,where orographic lifting is obvious,and(iii)subsequent formation of the convective storm producing the extreme rainfall in Zhengzhou.In particular,the model generates the maximum rainfall rate of 233 mm h^(-1)and 40-h accumulated rainfall of 704 mm,corresponding well to the observed extreme values of 201.9 mm h^(-1)and 818 mm,at nearly observed timing and location.Importantly,the model reproduces an intense quasi-stationary,well-organized meso-γ-scale convective system,surrounded by an arc-shaped convergence zone,allowing the development of convective updrafts in a three-quarter circle around the convective system,in a way similar to“multidirectional pumping,”attracting all associated precipitation overlaid and concentrated into the same trailing region to generate the extreme hourly rainfall over Zhengzhou.Our study emphasizes the significant contribution of the unique dynamic structure of the well-organized meso-γ-scale convective system to the record-high hourly rainfall.A possible dynamic mechanism for short-time extreme rainfall production is proposed.That is,the arc-shaped convergence zone of the mesoscale convective system,acting like multidirectional lifting pumps,transports precipitation from different directions into the same region,and thus produces the extreme rainfall.The results gained herein may shed new light on better understanding and forecasting of short-time extreme rainfall.展开更多
Devastating tornadoes in China have received growing attention in recent years, but little is known about their formation, structure, and evolution on the tornadic scale. Most of these tornadoes develop within the Eas...Devastating tornadoes in China have received growing attention in recent years, but little is known about their formation, structure, and evolution on the tornadic scale. Most of these tornadoes develop within the East Asian monsoon regime, in an environment quite different from tornadoes in the U.S. In this study, we used an idealized, highresolution(25-m grid spacing) numerical simulation to investigate the deadly EF4(Enhanced Fujita scale category 4)tornado that occurred on 23 June 2016 and claimed 99 lives in Yancheng, Jiangsu Province. A tornadic supercell developed in the simulation that had striking similarities to radar observations. The violent tornado in Funing County was reproduced, exceeding EF4(74 ms–1), consistent with the on-site damage survey. It was accompanied by a funnel cloud that extended to the surface, and exhibited a double-helix vorticity structure. The signal of tornado genesis was found first at the cloud base in the pressure perturbation field, and then developed both upward and downward in terms of maximum vertical velocity overlapping with the intense vertical vorticity centers. The tornado's demise was found to accompany strong downdrafts overlapping with the intense vorticity centers. One of the interesting findings of this work is that a violent surface vortex was able to be generated and maintained, even though the simulation employed a free-slip lower boundary condition. The success of this simulation, despite using an idealized numerical approach, provides a means to investigate more historical tornadoes in China.展开更多
Tornadoes are highly localized severe weather phenomena and have been of increasing concern in China [1] in recent years, especially after the sinking of the Oriental Star in 2015 [2] and severe tornado damage in Yanc...Tornadoes are highly localized severe weather phenomena and have been of increasing concern in China [1] in recent years, especially after the sinking of the Oriental Star in 2015 [2] and severe tornado damage in Yancheng in 2016 (3)Tornadoes induced by tropical cyclones, however, have received little attention.A recent study has shown that a large number of tornado-scale vortices can be produced at the inner edge of the intense eyewallconvection of tropical cyclones [4].展开更多
Using China New Generation Weather Radar(CINRAD) level-II data, the original algorithms for removing isolated non-meteorological echoes and ground clutters in radar data, which have been applied to Weather Surveillanc...Using China New Generation Weather Radar(CINRAD) level-II data, the original algorithms for removing isolated non-meteorological echoes and ground clutters in radar data, which have been applied to Weather Surveillance Radar-1988 Doppler(WSR-88 D) in the USA and Severe Weather Automatic Nowcast(SWAN) system in China, are modified and improved. To remove isolated non-meteorological echoes, the new algorithm introduces a constraint parameter(Po) to distinguish whether a window of 5 × 5 points is isolated as external echoes. A statistical analysis of150 radar scans(5 cases, with each case comprising 30 scans) under three different echo types(small-scale convection, typhoon, and large-scale synoptic system) shows that the constraint parameter Po ≤ 0.167 is suitable for removing isolated non-meteorological echoes while preserving the edge of meteorological echoes. A new parameter, NDZ,which promotes the ability of the algorithm to identify the ground clutters appearing at two adjacent elevation angles,is constructed based on the vertical continuity of reflectivity. These improved algorithms are tested for four cases(three cases of isolated non-meteorological echoes and one case of ground clutters). Based on the statistics of 232 volume scans of radar data(on a temporal resolution of 1 h) measured at Nanchang station from 0000 UTC 5 to 1600 UTC 14 March 2015, it is found that the improved algorithms not only eliminate most(over 95% under clear-sky conditions) of the isolated non-meteorological echoes and ground clutters(including those appearing at two adjacent elevation angles), but also well preserve the structure of meteorological echoes(storms).展开更多
From July 19 to 21,2021,Henan,a province in northern China(NC),was affected by severe flooding(referred to hereafter as“21·7”)caused by a prolonged record-breaking extreme precipitation(EP)event.Understanding t...From July 19 to 21,2021,Henan,a province in northern China(NC),was affected by severe flooding(referred to hereafter as“21·7”)caused by a prolonged record-breaking extreme precipitation(EP)event.Understanding the extremes of the large-scale circulation pattern during“21·7”is essential for predicting EP events and preventing future disasters.In this study,daily atmospheric large-scale circulations over NC in the summers from 1979 to 2021 were investigated using the circulation classification method of an obliquely rotated principal component analysis in T-mode(PCT).The geopotential heights at 500 hPa and 925 hPa were applied successively in classification.Among the nine summer circulation patterns found at 500 hPa,the three days of“21·7”belonged to the Type 8 pattern,which had the second highest probability of EP days among all patterns.It was characterized by a southeasterly wind toward North China Plain driven by a dipole geopotential height field,with the West Pacific subtropical high(WPSH)extending far north to 30°N and low pressure to the south near NC.Tropical cyclones(TCs)occurred on 72.5%of EP days,in which larger amounts of precipitation and a longer duration of EP days were found along the mountains in NC,as compared with other patterns.The distribution of EP events under this pattern was mainly influenced by the location of the low pressure at 925 hPa in the dipole.The subtype 8-3 circulation,with low pressure in the east of Taiwan Island,included“21·7”and accounted for 1.6%of all summer days.Typhoon In-fa,together with the WPSH,gave rise to intense column integrated moisture flux convergence(IMFC)via the southeasterly wind to Henan,which occurred continuously during the 3 days of“21·7”,resulting in the largest(second largest)mean IMFC among 3 consecutive EP days under type 8(all types)during the past 43 summers in NC.Further analysis revealed that the large-scale dynamic process could not completely explain the record-breaking EP during“21·7”,indicating possible contributions of other dynamic processes related to meso-scale convective storms.展开更多
Deep ultraviolet(DUV) optical wireless communications have seen increased interest in recent years due to the unique properties of light in this spectral region. However, the reported DUV data rates remain significant...Deep ultraviolet(DUV) optical wireless communications have seen increased interest in recent years due to the unique properties of light in this spectral region. However, the reported DUV data rates remain significantly lower than comparable demonstrations at visible wavelengths due to lower modulation bandwidths and/or output power of the sources. Here, we present a wavelength division multiplexing demonstration using three UV microlight-emitting diodes emitting at nominal peak wavelengths of 285, 317, and 375 nm, respectively, each with an emitting area of approximately 1369 μm^(2)(equivalent to circular device pixels of diameter;0 μm). Using orthogonal frequency division multiplexing, data rates of 4.17, 3.02, and 3.13 Gbps were achieved from the 285, 317, and 375 nm devices, respectively, for a combined data rate of 10.32 Gbps transmitted over a distance of 0.5 m.展开更多
Lanzhou is a typical mountainous city with severe air pollution in northwestern China. This study uses hourly observational data of air pollutants at five air quality monitoring sites in Lanzhou from July to December ...Lanzhou is a typical mountainous city with severe air pollution in northwestern China. This study uses hourly observational data of air pollutants at five air quality monitoring sites in Lanzhou from July to December 2015 to discuss data quality control and the representativeness of the monitoring sites(four urban sites and one suburban site). A fuzzy matrix is applied to study primary air pollutants. The results show that of the six routinely monitored pollutants,the primary pollutant is PM_10 during the study period. Based on lag correlation analysis and one-way analysis of variance, it is concluded that there are redundant observations at the four urban sites for the timely diffusion and transport of air pollutants from the same general area. The coefficient of divergence(COD) method is then used to evaluate the spatial distribution differences, and the primary air pollutant PM_10 shows differences at each site. COD can be used as a positive indicator to describe site representativeness. To evaluate the overall air pollution in the valley, correlation analysis is performed between the PM_10 concentration retrieved from aerosol optical depth satellite data and the concentration from the four urban monitoring sites. Among these, the correlation between the workers' hospital site data and the retrieval data is the highest, passing the 90% confidence level. A new representative evaluation model for air quality monitoring sites, R_s = 0.77 COD + 0.23R_(retrieval), is established by using COD and correlation coefficients between routine observations and satellite retrieval products. From this model, it can be concluded that the biological products institute site in Lanzhou is the most representative site for the evaluation of air pollution out of the four urban air quality monitoring sites from July to December 2015.展开更多
Objective:To investigate current autologous transplantation methods and sites of ovarian tissues in sheep.Methods:Sheep ovaries were resected.Ovarian cortices were sliced and transplanted orthotopically into the ovari...Objective:To investigate current autologous transplantation methods and sites of ovarian tissues in sheep.Methods:Sheep ovaries were resected.Ovarian cortices were sliced and transplanted orthotopically into the ovarian mesangial latum and heterotopically into the greater omentum and under groin skin.The grafts were removed two months after transplantation and examined to evaluate the survival of follicles(hematoxylin-eosin staining)and help determining feasible graft sites and transplantation methods.Results:Graft nodules were found in the transplanted sites.HE staining of the grafts showed that multiple primordial follicles were able to survive in the grafts on both sides of the ovarian mesangial latum,the right side of the greater omentum,and the left inguinal subcutaneous tissue.Secondary or cystic follicles were found in almost all of the grafts.Conclusion:The ovarian mesangial latum,the greater omentum and the inguinal subcutaneous tissue can be used as autologous transplantation sites,where sheep ovarian tissue can survive and the follicles grow and develop in good condition.展开更多
基金The National Natural Science Foundation of China(Grant Nos.42030610 and 42075083)the Innovation and Development Project of China Meteorological Administration(CXFZ2022J014)supported this study.
文摘This study investigates the influences of urban land cover on the extreme rainfall event over the Zhengzhou city in central China on 20 July 2021 using the Weather Research and Forecasting model at a convection-permitting scale[1-km resolution in the innermost domain(d3)].Two ensembles of simulation(CTRL,NURB),each consisting of 11 members with a multi-layer urban canopy model and various combinations of physics schemes,were conducted using different land cover scenarios:(i)the real urban land cover,(ii)all cities in d3 being replaced with natural land cover.The results suggest that CTRL reasonably reproduces the spatiotemporal evolution of rainstorms and the 24-h rainfall accumulation over the key region,although the maximum hourly rainfall is underestimated and displaced to the west or southwest by most members.The ensemble mean 24-h rainfall accumulation over the key region of heavy rainfall is reduced by 13%,and the maximum hourly rainfall simulated by each member is reduced by 15–70 mm in CTRL relative to NURB.The reduction in the simulated rainfall by urbanization is closely associated with numerous cities/towns to the south,southeast,and east of Zhengzhou.Their heating effects jointly lead to formation of anomalous upward motions in and above the planetary boundary layer(PBL),which exaggerates the PBL drying effect due to reduced evapotranspiration and also enhances the wind stilling effect due to increased surface friction in urban areas.As a result,the lateral inflows of moisture and high-θe(equivalent potential temperature)air from south and east to Zhengzhou are reduced.
文摘A mesoscale convective system(MCS)is an organized cluster of thunderstorms known to be the most important convective mode in causing disastrous high-impact weather,such as heavy rainfall,hail,damaging winds,and tornadoes.The small spatial scale and fast temporal evolution of MCSs make their observation and prediction very challenging.East Asia is home to the world’s most prominent monsoon,setting the stage for various severe convective weather events.MCSs and their associated high-impact weather have long been critical issues of concern;as such,their research efforts are valued by governments in East Asia.
基金supported by the Fundamental Research Funds for the Central Universities[YWF-22-K-101]National Natural Science Foundation of China[12202120]Science Technology and Innovation Program of Shenzhen[JCYJ20220531095210022].
文摘Liquid crystal elastomers are active materials that combine the anisotropic properties of liquid crystals with the elasticity of polymer networks.The LCEs exhibit remarkable reversible contraction and elongation capabilities in response to external stimuli,rendering them highly promising for diverse applications,such as soft robotics,haptic devices,shape morphing structures,etc,However,the predominant reliance on heating as the driving stimulus for LCEs has limited their practical applications.This drawback can be effectively addressed by incorporating fllers,which can generate heat under various stimuli.The recent progress in LCE composites has significantly expanded the application potential of LCEs.In this minireview,we present the design strategies for soft actuators with LCE composites,followed by a detailed exploration of photothermal and electrothermal LCE.composites as prominent examples.Furthermore,we provide an outlook on the challenges and opportunities in the feld of LCE composites.
基金Supported by the National Key Research and Development Program of China(2017YFC1501806,2018YFC1507404)National Natural Science Foundation of China(42075083)。
文摘In this study,the unprecedented extreme rainfall event during 19-20 July 2021,which caused devastating flooding in Zhengzhou City and its nearby areas,is examined based on observational data analysis and WRF model 40-h simulations on 1-km horizontal resolution.The results show that the model successfully reproduces(i)major synopticscale weather systems(i.e.,the western Pacific subtropical high,the Tibetan high,two typhoons,and the Huang-Huai cyclone),(ii)convective initiation along the east to north edge of the Songshan Mountain,where orographic lifting is obvious,and(iii)subsequent formation of the convective storm producing the extreme rainfall in Zhengzhou.In particular,the model generates the maximum rainfall rate of 233 mm h^(-1)and 40-h accumulated rainfall of 704 mm,corresponding well to the observed extreme values of 201.9 mm h^(-1)and 818 mm,at nearly observed timing and location.Importantly,the model reproduces an intense quasi-stationary,well-organized meso-γ-scale convective system,surrounded by an arc-shaped convergence zone,allowing the development of convective updrafts in a three-quarter circle around the convective system,in a way similar to“multidirectional pumping,”attracting all associated precipitation overlaid and concentrated into the same trailing region to generate the extreme hourly rainfall over Zhengzhou.Our study emphasizes the significant contribution of the unique dynamic structure of the well-organized meso-γ-scale convective system to the record-high hourly rainfall.A possible dynamic mechanism for short-time extreme rainfall production is proposed.That is,the arc-shaped convergence zone of the mesoscale convective system,acting like multidirectional lifting pumps,transports precipitation from different directions into the same region,and thus produces the extreme rainfall.The results gained herein may shed new light on better understanding and forecasting of short-time extreme rainfall.
基金Supported by the National Natural Science Foundation of China(41705028,41405095,and 41405006)Basic Research Fund of the Chinese Academy of Meteorological Sciences[2017Y018,2015Z003,and 2017Z017(2017LASW-A02)]
文摘Devastating tornadoes in China have received growing attention in recent years, but little is known about their formation, structure, and evolution on the tornadic scale. Most of these tornadoes develop within the East Asian monsoon regime, in an environment quite different from tornadoes in the U.S. In this study, we used an idealized, highresolution(25-m grid spacing) numerical simulation to investigate the deadly EF4(Enhanced Fujita scale category 4)tornado that occurred on 23 June 2016 and claimed 99 lives in Yancheng, Jiangsu Province. A tornadic supercell developed in the simulation that had striking similarities to radar observations. The violent tornado in Funing County was reproduced, exceeding EF4(74 ms–1), consistent with the on-site damage survey. It was accompanied by a funnel cloud that extended to the surface, and exhibited a double-helix vorticity structure. The signal of tornado genesis was found first at the cloud base in the pressure perturbation field, and then developed both upward and downward in terms of maximum vertical velocity overlapping with the intense vertical vorticity centers. The tornado's demise was found to accompany strong downdrafts overlapping with the intense vorticity centers. One of the interesting findings of this work is that a violent surface vortex was able to be generated and maintained, even though the simulation employed a free-slip lower boundary condition. The success of this simulation, despite using an idealized numerical approach, provides a means to investigate more historical tornadoes in China.
基金supported by the Ministry of Science and Technology of China (2018YFC1506103)the National Natural Science Foundation of China (41705028)the Basic Research Fund of the Chinese Academy of Meteorological Sciences (2017Y018)
文摘Tornadoes are highly localized severe weather phenomena and have been of increasing concern in China [1] in recent years, especially after the sinking of the Oriental Star in 2015 [2] and severe tornado damage in Yancheng in 2016 (3)Tornadoes induced by tropical cyclones, however, have received little attention.A recent study has shown that a large number of tornado-scale vortices can be produced at the inner edge of the intense eyewallconvection of tropical cyclones [4].
基金Supported by the Jiangxi Provincial Department of Science and Technology project(20171BBG70004)Open Project of the State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences(2016LASW-N11)National Natural Science Foundation of China(41575098)
文摘Using China New Generation Weather Radar(CINRAD) level-II data, the original algorithms for removing isolated non-meteorological echoes and ground clutters in radar data, which have been applied to Weather Surveillance Radar-1988 Doppler(WSR-88 D) in the USA and Severe Weather Automatic Nowcast(SWAN) system in China, are modified and improved. To remove isolated non-meteorological echoes, the new algorithm introduces a constraint parameter(Po) to distinguish whether a window of 5 × 5 points is isolated as external echoes. A statistical analysis of150 radar scans(5 cases, with each case comprising 30 scans) under three different echo types(small-scale convection, typhoon, and large-scale synoptic system) shows that the constraint parameter Po ≤ 0.167 is suitable for removing isolated non-meteorological echoes while preserving the edge of meteorological echoes. A new parameter, NDZ,which promotes the ability of the algorithm to identify the ground clutters appearing at two adjacent elevation angles,is constructed based on the vertical continuity of reflectivity. These improved algorithms are tested for four cases(three cases of isolated non-meteorological echoes and one case of ground clutters). Based on the statistics of 232 volume scans of radar data(on a temporal resolution of 1 h) measured at Nanchang station from 0000 UTC 5 to 1600 UTC 14 March 2015, it is found that the improved algorithms not only eliminate most(over 95% under clear-sky conditions) of the isolated non-meteorological echoes and ground clutters(including those appearing at two adjacent elevation angles), but also well preserve the structure of meteorological echoes(storms).
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(Grant No.2019QZKK0105)the National Natural Science Foundation of China(Grant Nos.42030607&41975001)+1 种基金the 2018 Open Research Program of the State Key Laboratory of Severe Weather(Grant No.2018LASW-B17)Forecaster Research Project of China Meteorological Administration(Grant No.CMAYBY2019-137)。
文摘From July 19 to 21,2021,Henan,a province in northern China(NC),was affected by severe flooding(referred to hereafter as“21·7”)caused by a prolonged record-breaking extreme precipitation(EP)event.Understanding the extremes of the large-scale circulation pattern during“21·7”is essential for predicting EP events and preventing future disasters.In this study,daily atmospheric large-scale circulations over NC in the summers from 1979 to 2021 were investigated using the circulation classification method of an obliquely rotated principal component analysis in T-mode(PCT).The geopotential heights at 500 hPa and 925 hPa were applied successively in classification.Among the nine summer circulation patterns found at 500 hPa,the three days of“21·7”belonged to the Type 8 pattern,which had the second highest probability of EP days among all patterns.It was characterized by a southeasterly wind toward North China Plain driven by a dipole geopotential height field,with the West Pacific subtropical high(WPSH)extending far north to 30°N and low pressure to the south near NC.Tropical cyclones(TCs)occurred on 72.5%of EP days,in which larger amounts of precipitation and a longer duration of EP days were found along the mountains in NC,as compared with other patterns.The distribution of EP events under this pattern was mainly influenced by the location of the low pressure at 925 hPa in the dipole.The subtype 8-3 circulation,with low pressure in the east of Taiwan Island,included“21·7”and accounted for 1.6%of all summer days.Typhoon In-fa,together with the WPSH,gave rise to intense column integrated moisture flux convergence(IMFC)via the southeasterly wind to Henan,which occurred continuously during the 3 days of“21·7”,resulting in the largest(second largest)mean IMFC among 3 consecutive EP days under type 8(all types)during the past 43 summers in NC.Further analysis revealed that the large-scale dynamic process could not completely explain the record-breaking EP during“21·7”,indicating possible contributions of other dynamic processes related to meso-scale convective storms.
基金Engineering and Physical Sciences Research Council (EP/M01326X/1, EP/S001751/1, EP/T00097X/1)。
文摘Deep ultraviolet(DUV) optical wireless communications have seen increased interest in recent years due to the unique properties of light in this spectral region. However, the reported DUV data rates remain significantly lower than comparable demonstrations at visible wavelengths due to lower modulation bandwidths and/or output power of the sources. Here, we present a wavelength division multiplexing demonstration using three UV microlight-emitting diodes emitting at nominal peak wavelengths of 285, 317, and 375 nm, respectively, each with an emitting area of approximately 1369 μm^(2)(equivalent to circular device pixels of diameter;0 μm). Using orthogonal frequency division multiplexing, data rates of 4.17, 3.02, and 3.13 Gbps were achieved from the 285, 317, and 375 nm devices, respectively, for a combined data rate of 10.32 Gbps transmitted over a distance of 0.5 m.
基金Supported by the National Key R&D Program of China(2017YFC1501805)Drought Meteorology Research Project(IAM201603)Gansu Province Natural Science Foundation(18JR3RA278)
文摘Lanzhou is a typical mountainous city with severe air pollution in northwestern China. This study uses hourly observational data of air pollutants at five air quality monitoring sites in Lanzhou from July to December 2015 to discuss data quality control and the representativeness of the monitoring sites(four urban sites and one suburban site). A fuzzy matrix is applied to study primary air pollutants. The results show that of the six routinely monitored pollutants,the primary pollutant is PM_10 during the study period. Based on lag correlation analysis and one-way analysis of variance, it is concluded that there are redundant observations at the four urban sites for the timely diffusion and transport of air pollutants from the same general area. The coefficient of divergence(COD) method is then used to evaluate the spatial distribution differences, and the primary air pollutant PM_10 shows differences at each site. COD can be used as a positive indicator to describe site representativeness. To evaluate the overall air pollution in the valley, correlation analysis is performed between the PM_10 concentration retrieved from aerosol optical depth satellite data and the concentration from the four urban monitoring sites. Among these, the correlation between the workers' hospital site data and the retrieval data is the highest, passing the 90% confidence level. A new representative evaluation model for air quality monitoring sites, R_s = 0.77 COD + 0.23R_(retrieval), is established by using COD and correlation coefficients between routine observations and satellite retrieval products. From this model, it can be concluded that the biological products institute site in Lanzhou is the most representative site for the evaluation of air pollution out of the four urban air quality monitoring sites from July to December 2015.
基金We are grateful for the financial support provided by the National key R&D program of China(No.2016YFA0201404 and 2015BAI13B06).
文摘Objective:To investigate current autologous transplantation methods and sites of ovarian tissues in sheep.Methods:Sheep ovaries were resected.Ovarian cortices were sliced and transplanted orthotopically into the ovarian mesangial latum and heterotopically into the greater omentum and under groin skin.The grafts were removed two months after transplantation and examined to evaluate the survival of follicles(hematoxylin-eosin staining)and help determining feasible graft sites and transplantation methods.Results:Graft nodules were found in the transplanted sites.HE staining of the grafts showed that multiple primordial follicles were able to survive in the grafts on both sides of the ovarian mesangial latum,the right side of the greater omentum,and the left inguinal subcutaneous tissue.Secondary or cystic follicles were found in almost all of the grafts.Conclusion:The ovarian mesangial latum,the greater omentum and the inguinal subcutaneous tissue can be used as autologous transplantation sites,where sheep ovarian tissue can survive and the follicles grow and develop in good condition.