The accurate simulation of regional-scale winter wheat yield is important for national food security and the balance of grain supply and demand in China.Presently,most remote sensing process models use the“biomass...The accurate simulation of regional-scale winter wheat yield is important for national food security and the balance of grain supply and demand in China.Presently,most remote sensing process models use the“biomass×harvest index(HI)”method to simulate regional-scale winter wheat yield.However,spatiotemporal differences in HI contribute to inaccuracies in yield simulation at the regional scale.Time-series dry matter partition coefficients(Fr)can dynamically reflect the dry matter partition of winter wheat.In this study,Fr equations were fitted for each organ of winter wheat using site-scale data.These equations were then coupled into a process-based and remote sensingdriven crop yield model for wheat(PRYM-Wheat)to improve the regional simulation of winter wheat yield over the North China Plain(NCP).The improved PRYM-Wheat model integrated with the fitted Fr equations(PRYM-Wheat-Fr)was validated using data obtained from provincial yearbooks.A 3-year(2000-2002)averaged validation showed that PRYM-Wheat-Fr had a higher coefficient of determination(R^(2)=0.55)and lower root mean square error(RMSE=0.94 t ha^(-1))than PRYM-Wheat with a stable HI(abbreviated as PRYM-Wheat-HI),which had R^(2) and RMSE values of 0.30 and 1.62 t ha^(-1),respectively.The PRYM-Wheat-Fr model also performed better than PRYM-Wheat-HI for simulating yield in verification years(2013-2015).In conclusion,the PRYM-Wheat-Fr model exhibited a better accuracy than the original PRYM-Wheat model,making it a useful tool for the simulation of regional winter wheat yield.展开更多
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
Forests account for 80%of the total carbon exchange between the atmosphere and terrestrial ecosystems.Thus,to better manage our responses to global warming,it is important to monitor and assess forest aboveground carb...Forests account for 80%of the total carbon exchange between the atmosphere and terrestrial ecosystems.Thus,to better manage our responses to global warming,it is important to monitor and assess forest aboveground carbon and forest aboveground biomass(FAGB).Different levels of detail are needed to estimate FAGB at local,regional and national scales.Multi-scale remote sensing analysis from high,medium and coarse spatial resolution data,along with field sampling,is one approach often used.However,the methods developed are still time consuming,expensive,and inconvenient for systematic monitoring,especially for developing countries,as they require vast numbers of field samples for upscaling.Here,we recommend a convenient two-scale approach to estimate FAGB that was tested in our study sites.The study was conducted in the Chitwan district of Nepal using GeoEye-1(0.5 m),Landsat(30 m)and Google Earth very high resolution(GEVHR)Quickbird(0.65 m)images.For the local scale(Kayerkhola watershed),tree crowns of the area were delineated by the object-based image analysis technique on GeoEye images.An overall accuracy of 83%was obtained in the delineation of tree canopy cover(TCC)per plot.A TCC vs.FAGB model was developed based on the TCC estimations from GeoEye and FAGB measurements from field sample plots.A coefficient of determination(R2)of 0.76 was obtained in the modelling,and a value of 0.83 was obtained in the validation of the model.To upscale FAGB to the entire district,open source GEVHR images were used as virtual field plots.We delineated their TCC values and then calculated FAGB based on a TCC versus FAGB model.Using the multivariate adaptive regression splines machine learning algorithm,we developed a model from the relationship between the FAGB of GEVHR virtual plots with predictor parameters from Landsat 8 bands and vegetation indices.The model was then used to extrapolate FAGB to the entire district.This approach considerably reduced the need for field data and commercial very high resolution imagery while achieving two-scale forest information and FAGB estimates at high resolution(30 m)and accuracy(R2=0.76 and 0.7)with minimal error(RMSE=64 and 38 tons ha-1)at local and regional scales.This methodology is a promising technique for cost-effective FAGB and carbon estimations and can be replicated with limited resources and time.The method is especially applicable for developing countries that have low budgets for carbon estimations,and it is also applicable to the Reducing Emissions from Deforestation and Forest Degradation(REDD?)monitoring reporting and verification processes.展开更多
Objective： To construct green fluorescent protein（GFP） retroviral vector（pLgXSN）, and to investigate the expression of GFP in primary rat myoblast. Methods： GFP cDNA was subcloned into the plasmid pLgXSN, and th...Objective： To construct green fluorescent protein（GFP） retroviral vector（pLgXSN）, and to investigate the expression of GFP in primary rat myoblast. Methods： GFP cDNA was subcloned into the plasmid pLgXSN, and the recombinant vector was transfected into packaging cell PT67. G418 was used to select positive colony. Myoblasts were infected by a high-titer viral supernatant. The recombinant retroviral plasmid vector was identified by restriction endonuclease analysis and DNA sequence analysis. Confocal microscopy and flow cytometry were used to detect the expression of GFP. Results： The GFP cDNA sequence was identical to that of GenBank. Recombinant retroviral plasmid vector pLgGFPSN was constructed successfully. The titer of the packaged recombinant retrovirus was 1×10^6 cfu/ml. Bright green fluorescence of the transfected cells was observed under confocal microscope 48 h after transfection. The transfection rate was 33%. The effective expression of GFP in myoblast infected by recombinant retrovirus lasted for 6 weeks. Conclusion： GFP gene could be effectively and stably expressed in myoblast, which suggests that GFP could act as a marker for studies on myoblast.展开更多
The aerosol can change the clouds properties;the clouds, however, affect the normal behavior of aerosol optical depth. Considerable effects arise while the interaction of aerosol and clouds unavoidably encounters the ...The aerosol can change the clouds properties;the clouds, however, affect the normal behavior of aerosol optical depth. Considerable effects arise while the interaction of aerosol and clouds unavoidably encounters the presence of greenhouse gases (GHGs) in atmosphere. This research discusses the influence of two selected aerosol types, on the clouds in Africa, over the selected sub-time series in the years 1980-2018. Sahara desert’s dust is mainly constituted by hematite minerals;which, in return, is mainly composed by the iron oxides, a powerful solar and infra-red radiation absorbing matter and thus a strong and direct radiative forcing agent. For that reason, together with the fact that it is windblown over the biggest region that surrounds the desert, dust is one of the strongly considered aerosol in this research. Besides, black carbon (BC), mostly from the anthropogenic biomass burning process in the mid latitude’s African savanna, is the second aerosol type selected for this research: it is one of the abundantly available aerosol types and it is one of the strongest atmospheric radiant energy absorbers. For sake of valid and trustworthy results, the data is collected from multiple satellite remote sensing tools and instruments, all targeting the aerosol-cloud interaction and effects. In this research, different measurements were carried out;those are the spatiotemporal averaged cloud cover, the aerosol (dust and BC) extinction optical thickness (AOT), the anomaly of aerosol optical depth (AAOD) as well as different scatter plots’ correlation analysis. For findings: the direct influence of hydrophilic BC on clouds formation in central African sub-region is experimentally demonstrated;the dust aerosol highly influences the North African sub-region’s cloud formation.展开更多
In the most popular NaYF_(4):Yb/Er upconversion nanoparticles(UCNPs),the red emission is attributed to four potential excitation routes encompassing two-and threephoton excitation processes.Consequently,this red emiss...In the most popular NaYF_(4):Yb/Er upconversion nanoparticles(UCNPs),the red emission is attributed to four potential excitation routes encompassing two-and threephoton excitation processes.Consequently,this red emission typically exhibits a super-quadratic dependency on near-infrared(NIR)excitation intensity,with the nonlinear order n being dependent on the individual contributions(Cis)of these four excitation routes.Notably,the Cis values are not constant but significantly impacted by the surface quenching of the UCNPs,leading to a decrease in the n value.However,a quantitative assessment of these variable Cis has not been undertaken,hindering a comprehensive understanding of the quenching effect on the UC mechanisms.In this work,we prepare four NaYF_(4):Yb/Er nanocrystal samples with varying degrees of surface quenching,achieving through the modulation of particle size and core-shell structure.We quantitatively evaluate the Cis values and identify the primary excitation route responsible for the red emission.Our results reveal that the contribution of three-photon excitation increases from 7%in the 30 nm bare core to 74%in 90 nm core with shell at an excitation intensity of 200 mW cm^(−2).This observation highlights the impact of surface quenching suppression.Furthermore,we discover that the quenching effect operates by reducing the lifetimes of the Yb^(3+)2F_(5/2)and Er^(3+)4S3/2 levels,while enhancing the NIR emission intensity ratio of the Er^(3+)4I_(13/2)→4I_(15/2)transition to the Yb^(3+)2F_(5/2)→2F_(7/2)transition.Our findings provide physical insights into the excitation mechanisms underlying the red UC emission in NaYF_(4):Yb/Er UCNPs.展开更多
In recent decades, climate warming has led to an increase in atmospheric water demand, a potential reduction in soil moisture and a rise in the frequency and intensity of droughts. This has intensified the effects of ...In recent decades, climate warming has led to an increase in atmospheric water demand, a potential reduction in soil moisture and a rise in the frequency and intensity of droughts. This has intensified the effects of water stress on plants, leading to more vegetated areas experiencing water stress [1,2]. Soil moisture (SM)and vapor pressure deficit (VPD) are considered the two main factors that exert water stress on vegetation activity and terrestrial productivity, thereby affecting the global carbon cycle [3].展开更多
Transparent phosphor ceramics have received increasing attention for high-brightness laser lighting,but commercially available phosphor ceramics are currently mainly limited to yellow YAG:Ce and green LuAG:Ce garnets,...Transparent phosphor ceramics have received increasing attention for high-brightness laser lighting,but commercially available phosphor ceramics are currently mainly limited to yellow YAG:Ce and green LuAG:Ce garnets,leaving a“cyan cavity”which is an obstacle to realizing full-color lighting.Achieving new phosphor ceramics capable of filling the cavity is a challenge.Herein,for the first time,cyan-green-emitting Ca_(3)Sc_(2)Si_(3)O_(12):Ce^(3+)(CSS:Ce)transparent ceramics have been successfully developed by two-step sintering technique under vacuum.The as-prepared CSS:Ce ceramics present high relative density of 99.7%and optical transmittance of 71%in the cyan-green spectral region.It exhibits an efficient band emission peaking at 504 nm(under 450 nm excitation)with internal/external quantum efficiency of 91%/62%.Furthermore,it has excellent thermal stability with a thermal quenching temperature(T_(0.5))of 838 K,approximately 100 K higher than that of LuAG:Ce ceramics(738 K).In addition,the CSS:Ce ceramics can withstand blue laser density of 45.6 W/mm^(2)and meanwhile generates cyan-green light with a forward luminous flux of 813 lm and forward luminous efficacy of 162 lm/W.The CSS:Ce transparent ceramics exhibit excellent luminescence performance comparable to the commercial LuAG:Ce ceramics and could be a highly promising color converter for high-brightness laser lighting.展开更多
In this paper,we studied the structure,expression and function of black carp insulin gene.The complete Mylopharyngodon piceus insulin(Mp-Ins)gene is 1,965 bp long and includes a 1,499 bp 5ʹ-untranslated region(UTR),a ...In this paper,we studied the structure,expression and function of black carp insulin gene.The complete Mylopharyngodon piceus insulin(Mp-Ins)gene is 1,965 bp long and includes a 1,499 bp 5ʹ-untranslated region(UTR),a 139 bp 3′-UTR with a poly(A)tail,and an open reading frame(ORF)of 327 bp.The predicted molecular weight of the recombinant Mp-Ins(rMp-Ins)protein is 11.87 kDa.The mRNA expression of Mp-Ins is upregulated in the brain and liver.After the injection of rMp-Ins,Mp-Ins mRNA transcript abundance was significantly upregulated in the liver.The rMp-Ins protein could inhibit the concentration of glycogen phosphorylase(GP),growth hormone(GH),fatty acid synthase(FAS),and insulin-like growth factors-1(IGF-1),and it also significantly increased the concentration of PI3K.Additionally,the injection of rMp-Ins did not have a significant impact on the glucose-6-phosphatase(G6Pase)content in blood.In situ hybridization results showed that the positive signal of the Mp-Ins gene was mainly concentrated in the cell nucleus of brain tissue and the cell membrane of liver tissue and muscle tissue.Together,these results demonstrated that Mp-Ins plays an important role in growth and metabolism in M.piceus.展开更多
Phosphor-converted white light-emitting diodes for indoor illumination need to be warm-white(i.e.,correlated color temperature,4000 K)with good color rendition(i.e.,color rendering index.80).However,no single-phosphor...Phosphor-converted white light-emitting diodes for indoor illumination need to be warm-white(i.e.,correlated color temperature,4000 K)with good color rendition(i.e.,color rendering index.80).However,no single-phosphor,single-emitting-center-converted white light-emitting diodes can simultaneously satisfy the color temperature and rendition requirements due to the lack of sufficient red spectral component in the phosphors’emission spectrum.Here,we report a new yellow Ba_(0.93)Eu_(0.07)Al_(2)O_(4) phosphor that has a new orthorhombic lattice structure and exhibits a broad yellow photoluminescence band with sufficient red spectral component.Warm-white emissions with correlated color temperature,4000 K and color rendering index.80 were readily achieved when combining the Ba_(0.93)Eu_(0.07)Al_(2)O_(4) phosphor with a blue light-emitting diode(440–470 nm).This study demonstrates that warm-white light-emitting diodes with high color rendition(i.e.,color rendering index.80)can be achieved based on single-phosphor,single-emitting-center conversion.展开更多
The rare earth Er^(3+) and Yb^(3+) codoped system is the most attractive for showcasing energy transfer upconversion.This system can generate green and red emissions from Er^(3+) under infrared excitation of the sensi...The rare earth Er^(3+) and Yb^(3+) codoped system is the most attractive for showcasing energy transfer upconversion.This system can generate green and red emissions from Er^(3+) under infrared excitation of the sensitizer Yb^(3+).It is well known that the red-emitting state can be populated from the upper green-emitting state.The contribution of multiphonon relaxation to this population is generally considered important at low excitation densities.Here,we demonstrate for the first time the importance of a previously proposed but neglected mechanism described as a cross relaxation energy transfer from Er^(3+) to Yb^(3+),followed by an energy back transfer within the same Er^(3+)–Yb^(3+) pair.A luminescence spectroscopy study of cubic Y_(2)O_(3):Er^(3+),Yb^(3+) indicates that this mechanism can be more efficient than multiphonon relaxation,and it can even make a major contribution to the red upconversion.The study also revealed that the energy transfers involved in this mechanism take place only in the nearest Er^(3+)–Yb^(3+) pairs,and thus,it is fast and efficient at low excitation densities.Our results enable a better understanding of upconversion processes and properties in the Er^(3+)–Yb^(3+) system.展开更多
Coarse columnar β grains result in anisotropic mechanical properties in Ti alloys deposited by additive manufacturing. This study reports that Ti-6Al-4V alloy fabricated by coaxial electron beam wire feeding additive...Coarse columnar β grains result in anisotropic mechanical properties in Ti alloys deposited by additive manufacturing. This study reports that Ti-6Al-4V alloy fabricated by coaxial electron beam wire feeding additive manufacturing presents a weak anisotropy, high strength and ductility. The superior tensile property arises from a microstructure with fine equiaxed β grains(EGβ), discontinuous grain boundary α phase and short intragranular α lamellae. A large region of fine EGβ arises from a special combination of the temperature gradient and solidification rate, and attractive α morphology is caused by solid phase transformations during interpass thermal cycling and post heat treatments.展开更多
Static coarsening mechanism of selective laser melted(SLMed) Ti–6Al–4V with a lamellar microstructure was established at temperatures from 700℃ to 950℃. Microstructure evolution revealed that high heat treatment t...Static coarsening mechanism of selective laser melted(SLMed) Ti–6Al–4V with a lamellar microstructure was established at temperatures from 700℃ to 950℃. Microstructure evolution revealed that high heat treatment temperature facilitated martensite decomposition and promoted lamellae growth. At each temperature, the growth rate decreased with increasing holding time. The static coarsening behaviour of SLMed Ti–6Al–4V can be interpreted by Lifshitz, Slyozov, and Wagner(LSW) theory. The coarsening coefficient were 0.33, 0.33–0.4, 0.4–0.5 for 700–800℃, 900℃ and 950℃, respectively. This indicated the coarsening mechanism was bulk diffusion at 700–800℃, and a combination of bulk diffusion and interface reaction at 900℃ and 950℃ conditions.展开更多
Analysis of the formation and evolution of urban surface thermal environment is crucial for urban planning and improving the environment of a settlement.Qingdao was selected in this study as a typical coastal city und...Analysis of the formation and evolution of urban surface thermal environment is crucial for urban planning and improving the environment of a settlement.Qingdao was selected in this study as a typical coastal city undergoing rapid urbanization,and the spatiotemporal dynamic characteristics of its urban surface thermal environment from2010 to 2019 were evaluated.The random forest(RF)algorithm was adopted to obtain its land surface temperature(LST)map with 30-m resolution by downscaling the Moderate Resolution Imaging Spectroradiometer(MODIS)LST product;the remote sensing indices emphasizing different land cover types,LST calculated by the radiative transfer equation,and elevation were used as input variables in the algorithm.The heat island intensity(HII),urban heat island(UHI)volume,and UHI grade were used to analyze the spatiotemporal dynamic characteristics of the urban surface thermal environment in Qingdao.The results show an increasing trend in average HII between 1.1 and 2.52°C in the study area over the past 10 years.The northern city appeared to have the highest UHI volume,while change of the UHI volume in Huangdao District of southwestern Qingdao was the most significant.The areas with high HII have gradually expanded during the last 10 years,and the areas with a 10-yr persistently high HII are distributed mainly in old urban areas with high building density and a dense population.Different factors may influence UHI,such as artificial heat sources,surface heat sources,and hybrid heat sources.Finally,adjusting the urban structure,increasing the vegetated area,and changing building colors are proposed to mitigate UHI in the areas with continuously high HII.展开更多
Evapotranspiration(ET)is a pivotal process for ecosystem water budgets and accounts for a substantial portion of the global energy balance.In this paper,the exited actual ETmain datasets in global scale,and the global...Evapotranspiration(ET)is a pivotal process for ecosystem water budgets and accounts for a substantial portion of the global energy balance.In this paper,the exited actual ETmain datasets in global scale,and the global ET modeling and estimates were focused on discussion.The Source energy balance(SEB)models,empirical models and other process-based models are summarized.Accuracy for ET estimates by SEBmodels highly depends on accurate surface temperature retrieval,and SEB models are hard to apply in large heterogeneous surface.The Penman-Monteith(PM)equations are thought to be with considerable sound mechanism.However,it involves large number of parameters,which are not all global available.A simplified PM equation by Priestley and Taylor(PT)is found to perform well on well-watered surface.For both PM and PT equations in estimating ET,the key is to consider the constraint from surface resistance primarily water stress.Empiricalmodels are simple but the accuracy of which highly depends on training samples.Coupling satellite data into ET models can improve ET estimates with higher resolution spatiotemporal information inputs;However,finding the most proper way to estimate global ET remains problematic.Several reasons for this issue are also analyzed in this review.展开更多
Land use change can have a strong impact on soil carbon dynamics and carbon stocks in urban areas. Due to rapid urbanization, large areas of land have been paved, and other areas have undergone rapid land use change. ...Land use change can have a strong impact on soil carbon dynamics and carbon stocks in urban areas. Due to rapid urbanization, large areas of land have been paved, and other areas have undergone rapid land use change. Evaluation of the impact of urbanization on carbon dynamics and carbon stock （30 cm） has become an issue of urgent concern. The soil carbon dynamics, due to rapid land use change in Tianjin Binhai New Area of China, have been simulated in this paper using the RothC model. Because this area is saline, a modified version of RothC that includes a salt rate modifier provided more accurate simulations than the original model. The conversion to urban green land was not accurately simulated by either of the models because of the undefined changes in soil and plant conditions. According to the model, changes of arable to grassland resulted in a decline in soil carbon stocks, and changes of grassland to forest and grassland to arable resulted in increased soil carbon stocks in this area. Across the whole area simulated, the total carbon stocks in 2010 had decreased due to land use change by 6.5% from the 1979 value. By 2050, a further decrease of 21.9% is expected according to the 2050 plan for land use and the continuing losses from the soils due to previous land use changes.展开更多
The influence of oxygen doping on resistive-switching characteristics of Ag/a-Si/p^＋-c-Si device was investigated. By oxygen doping in the growth process of amorphous silicon, the device resistive-switching performan...The influence of oxygen doping on resistive-switching characteristics of Ag/a-Si/p^＋-c-Si device was investigated. By oxygen doping in the growth process of amorphous silicon, the device resistive-switching performances, such as the ON/OFF resistance ratios, yield and stability were improved, which may be ascribed to the significant reduction of defect density because of oxygen incorporation. The device I-V characteristics are strongly dependent on the oxygen doping concentration. As the oxygen doping concentration increases, the Si-rich device gradually transforms to an oxygen-rich device, and the device yield, switching characteristics, and stability may be improved for silver/oxygen-doped a-Si/p^＋-c-Si device. Finally, the device resistive-switching mechanism was ana- lyzed. Key words： amorphous silicon; resistive switching; oxygen doping展开更多
基金supported by the National Natural Science Foundation of China(42101382 and 42201407)the Shandong Provincial Natural Science Foundation China(ZR2020QD016 and ZR2022QD120)。
文摘The accurate simulation of regional-scale winter wheat yield is important for national food security and the balance of grain supply and demand in China.Presently,most remote sensing process models use the“biomass×harvest index(HI)”method to simulate regional-scale winter wheat yield.However,spatiotemporal differences in HI contribute to inaccuracies in yield simulation at the regional scale.Time-series dry matter partition coefficients(Fr)can dynamically reflect the dry matter partition of winter wheat.In this study,Fr equations were fitted for each organ of winter wheat using site-scale data.These equations were then coupled into a process-based and remote sensingdriven crop yield model for wheat(PRYM-Wheat)to improve the regional simulation of winter wheat yield over the North China Plain(NCP).The improved PRYM-Wheat model integrated with the fitted Fr equations(PRYM-Wheat-Fr)was validated using data obtained from provincial yearbooks.A 3-year(2000-2002)averaged validation showed that PRYM-Wheat-Fr had a higher coefficient of determination(R^(2)=0.55)and lower root mean square error(RMSE=0.94 t ha^(-1))than PRYM-Wheat with a stable HI(abbreviated as PRYM-Wheat-HI),which had R^(2) and RMSE values of 0.30 and 1.62 t ha^(-1),respectively.The PRYM-Wheat-Fr model also performed better than PRYM-Wheat-HI for simulating yield in verification years(2013-2015).In conclusion,the PRYM-Wheat-Fr model exhibited a better accuracy than the original PRYM-Wheat model,making it a useful tool for the simulation of regional winter wheat yield.
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.
基金supported by the CAS Strategic Priority Research Program(No.XDA19030402)the National Key Research and Development Program of China(No.2016YFD0300101)+2 种基金the Natural Science Foundation of China(Nos.31571565,31671585)the Key Basic Research Project of the Shandong Natural Science Foundation of China(No.ZR2017ZB0422)Research Funding of Qingdao University(No.41117010153)
文摘Forests account for 80%of the total carbon exchange between the atmosphere and terrestrial ecosystems.Thus,to better manage our responses to global warming,it is important to monitor and assess forest aboveground carbon and forest aboveground biomass(FAGB).Different levels of detail are needed to estimate FAGB at local,regional and national scales.Multi-scale remote sensing analysis from high,medium and coarse spatial resolution data,along with field sampling,is one approach often used.However,the methods developed are still time consuming,expensive,and inconvenient for systematic monitoring,especially for developing countries,as they require vast numbers of field samples for upscaling.Here,we recommend a convenient two-scale approach to estimate FAGB that was tested in our study sites.The study was conducted in the Chitwan district of Nepal using GeoEye-1(0.5 m),Landsat(30 m)and Google Earth very high resolution(GEVHR)Quickbird(0.65 m)images.For the local scale(Kayerkhola watershed),tree crowns of the area were delineated by the object-based image analysis technique on GeoEye images.An overall accuracy of 83%was obtained in the delineation of tree canopy cover(TCC)per plot.A TCC vs.FAGB model was developed based on the TCC estimations from GeoEye and FAGB measurements from field sample plots.A coefficient of determination(R2)of 0.76 was obtained in the modelling,and a value of 0.83 was obtained in the validation of the model.To upscale FAGB to the entire district,open source GEVHR images were used as virtual field plots.We delineated their TCC values and then calculated FAGB based on a TCC versus FAGB model.Using the multivariate adaptive regression splines machine learning algorithm,we developed a model from the relationship between the FAGB of GEVHR virtual plots with predictor parameters from Landsat 8 bands and vegetation indices.The model was then used to extrapolate FAGB to the entire district.This approach considerably reduced the need for field data and commercial very high resolution imagery while achieving two-scale forest information and FAGB estimates at high resolution(30 m)and accuracy(R2=0.76 and 0.7)with minimal error(RMSE=64 and 38 tons ha-1)at local and regional scales.This methodology is a promising technique for cost-effective FAGB and carbon estimations and can be replicated with limited resources and time.The method is especially applicable for developing countries that have low budgets for carbon estimations,and it is also applicable to the Reducing Emissions from Deforestation and Forest Degradation(REDD?)monitoring reporting and verification processes.
文摘Objective： To construct green fluorescent protein（GFP） retroviral vector（pLgXSN）, and to investigate the expression of GFP in primary rat myoblast. Methods： GFP cDNA was subcloned into the plasmid pLgXSN, and the recombinant vector was transfected into packaging cell PT67. G418 was used to select positive colony. Myoblasts were infected by a high-titer viral supernatant. The recombinant retroviral plasmid vector was identified by restriction endonuclease analysis and DNA sequence analysis. Confocal microscopy and flow cytometry were used to detect the expression of GFP. Results： The GFP cDNA sequence was identical to that of GenBank. Recombinant retroviral plasmid vector pLgGFPSN was constructed successfully. The titer of the packaged recombinant retrovirus was 1×10^6 cfu/ml. Bright green fluorescence of the transfected cells was observed under confocal microscope 48 h after transfection. The transfection rate was 33%. The effective expression of GFP in myoblast infected by recombinant retrovirus lasted for 6 weeks. Conclusion： GFP gene could be effectively and stably expressed in myoblast, which suggests that GFP could act as a marker for studies on myoblast.
文摘The aerosol can change the clouds properties;the clouds, however, affect the normal behavior of aerosol optical depth. Considerable effects arise while the interaction of aerosol and clouds unavoidably encounters the presence of greenhouse gases (GHGs) in atmosphere. This research discusses the influence of two selected aerosol types, on the clouds in Africa, over the selected sub-time series in the years 1980-2018. Sahara desert’s dust is mainly constituted by hematite minerals;which, in return, is mainly composed by the iron oxides, a powerful solar and infra-red radiation absorbing matter and thus a strong and direct radiative forcing agent. For that reason, together with the fact that it is windblown over the biggest region that surrounds the desert, dust is one of the strongly considered aerosol in this research. Besides, black carbon (BC), mostly from the anthropogenic biomass burning process in the mid latitude’s African savanna, is the second aerosol type selected for this research: it is one of the abundantly available aerosol types and it is one of the strongest atmospheric radiant energy absorbers. For sake of valid and trustworthy results, the data is collected from multiple satellite remote sensing tools and instruments, all targeting the aerosol-cloud interaction and effects. In this research, different measurements were carried out;those are the spatiotemporal averaged cloud cover, the aerosol (dust and BC) extinction optical thickness (AOT), the anomaly of aerosol optical depth (AAOD) as well as different scatter plots’ correlation analysis. For findings: the direct influence of hydrophilic BC on clouds formation in central African sub-region is experimentally demonstrated;the dust aerosol highly influences the North African sub-region’s cloud formation.
基金supported by the National Natural Science Foundation of China(11874055,U22A20139,11904361,and 52102192)the Natural Science Foundation of Jilin Province(SKL202302024,20210201024GX,20220101208JC,and 20230101123JC)+1 种基金the Independent Innovation Project on State Key Laboratory of Luminescence and Applications(SKLA-Z-2023-11)the Opening Project Key Laboratory of Transparent Opto-functional Inorganic Material,Chinese Academy of Sciences。
文摘In the most popular NaYF_(4):Yb/Er upconversion nanoparticles(UCNPs),the red emission is attributed to four potential excitation routes encompassing two-and threephoton excitation processes.Consequently,this red emission typically exhibits a super-quadratic dependency on near-infrared(NIR)excitation intensity,with the nonlinear order n being dependent on the individual contributions(Cis)of these four excitation routes.Notably,the Cis values are not constant but significantly impacted by the surface quenching of the UCNPs,leading to a decrease in the n value.However,a quantitative assessment of these variable Cis has not been undertaken,hindering a comprehensive understanding of the quenching effect on the UC mechanisms.In this work,we prepare four NaYF_(4):Yb/Er nanocrystal samples with varying degrees of surface quenching,achieving through the modulation of particle size and core-shell structure.We quantitatively evaluate the Cis values and identify the primary excitation route responsible for the red emission.Our results reveal that the contribution of three-photon excitation increases from 7%in the 30 nm bare core to 74%in 90 nm core with shell at an excitation intensity of 200 mW cm^(−2).This observation highlights the impact of surface quenching suppression.Furthermore,we discover that the quenching effect operates by reducing the lifetimes of the Yb^(3+)2F_(5/2)and Er^(3+)4S3/2 levels,while enhancing the NIR emission intensity ratio of the Er^(3+)4I_(13/2)→4I_(15/2)transition to the Yb^(3+)2F_(5/2)→2F_(7/2)transition.Our findings provide physical insights into the excitation mechanisms underlying the red UC emission in NaYF_(4):Yb/Er UCNPs.
基金supported by the Finance Science and Technology Project of Hainan Province (ZDYF2021SHFZ063)the National Natural Science Foundation of China (42071425)+4 种基金the Chinese Academy of Sciences Strategic Priority Research Program (XDA19030402)“Taishan Scholar” Project of Shandong Province (TSXZ201712)Agri WATER (95338) in the framework of the ESAMOST Dragon 6 programthe Qingpu District Industry University Research Cooperation Development Foundation (202314)funded by the China Scholarship Council。
文摘In recent decades, climate warming has led to an increase in atmospheric water demand, a potential reduction in soil moisture and a rise in the frequency and intensity of droughts. This has intensified the effects of water stress on plants, leading to more vegetated areas experiencing water stress [1,2]. Soil moisture (SM)and vapor pressure deficit (VPD) are considered the two main factors that exert water stress on vegetation activity and terrestrial productivity, thereby affecting the global carbon cycle [3].
基金This work was partially supported by National Natural Science Foundation of China(Grant Nos.U22A20139,52102192,51772286,11974346,12074373,52072361,and 12074374)National Key R&D Program of China(Grant No.2021YFB3502701)+3 种基金Youth Innovation Promotion Association CAS(Grant No.2020222)Key Research and Development Program of Jilin Province(Grant Nos.20210201024GX,20220101208JC,and 20230101123JC)Changchun Science and Technology Planning Project(Grant No.21ZGY05)the Opening Project Key Laboratory of Transparent Opto-functional Inorganic Material,Chinese Academy of Sciences.
文摘Transparent phosphor ceramics have received increasing attention for high-brightness laser lighting,but commercially available phosphor ceramics are currently mainly limited to yellow YAG:Ce and green LuAG:Ce garnets,leaving a“cyan cavity”which is an obstacle to realizing full-color lighting.Achieving new phosphor ceramics capable of filling the cavity is a challenge.Herein,for the first time,cyan-green-emitting Ca_(3)Sc_(2)Si_(3)O_(12):Ce^(3+)(CSS:Ce)transparent ceramics have been successfully developed by two-step sintering technique under vacuum.The as-prepared CSS:Ce ceramics present high relative density of 99.7%and optical transmittance of 71%in the cyan-green spectral region.It exhibits an efficient band emission peaking at 504 nm(under 450 nm excitation)with internal/external quantum efficiency of 91%/62%.Furthermore,it has excellent thermal stability with a thermal quenching temperature(T_(0.5))of 838 K,approximately 100 K higher than that of LuAG:Ce ceramics(738 K).In addition,the CSS:Ce ceramics can withstand blue laser density of 45.6 W/mm^(2)and meanwhile generates cyan-green light with a forward luminous flux of 813 lm and forward luminous efficacy of 162 lm/W.The CSS:Ce transparent ceramics exhibit excellent luminescence performance comparable to the commercial LuAG:Ce ceramics and could be a highly promising color converter for high-brightness laser lighting.
基金This research was supported by China’s Agricultural Research System(CARS-45-03).
文摘In this paper,we studied the structure,expression and function of black carp insulin gene.The complete Mylopharyngodon piceus insulin(Mp-Ins)gene is 1,965 bp long and includes a 1,499 bp 5ʹ-untranslated region(UTR),a 139 bp 3′-UTR with a poly(A)tail,and an open reading frame(ORF)of 327 bp.The predicted molecular weight of the recombinant Mp-Ins(rMp-Ins)protein is 11.87 kDa.The mRNA expression of Mp-Ins is upregulated in the brain and liver.After the injection of rMp-Ins,Mp-Ins mRNA transcript abundance was significantly upregulated in the liver.The rMp-Ins protein could inhibit the concentration of glycogen phosphorylase(GP),growth hormone(GH),fatty acid synthase(FAS),and insulin-like growth factors-1(IGF-1),and it also significantly increased the concentration of PI3K.Additionally,the injection of rMp-Ins did not have a significant impact on the glucose-6-phosphatase(G6Pase)content in blood.In situ hybridization results showed that the positive signal of the Mp-Ins gene was mainly concentrated in the cell nucleus of brain tissue and the cell membrane of liver tissue and muscle tissue.Together,these results demonstrated that Mp-Ins plays an important role in growth and metabolism in M.piceus.
基金ZWP acknowledges funding by the US National Science Foundation(CAREER DMR-0955908)ZJG acknowledges support by the National Basic Research Programs of China(973 program,No.2012CB932504)+4 种基金JDB was supported by the Materials Sciences and Engineering Division,Office of Basic Energy Sciences(BES),US Department of Energy(DOE).Use of the APS beamline 11-BM-B for synchrotron X-ray powder diffractionbeamline 34-ID-E for polychromatic Laue microdiffraction was supported by the Scientific User Facilities Division of BES,US DOE.Use of the APS beamline 20-BM-B for X-ray absorption near edge structure measurement by CJS was supported by US DOE under Contract no.DE-AC02-06CH11357 with Argonne National Laboratory.The TEM characterization was sponsored by Oak Ridge National Laboratory’s Shared Research Equipment(ShaRE)User program,which is sponsored by the Division of Scientific User Facilities of BES,US DOE.
文摘Phosphor-converted white light-emitting diodes for indoor illumination need to be warm-white(i.e.,correlated color temperature,4000 K)with good color rendition(i.e.,color rendering index.80).However,no single-phosphor,single-emitting-center-converted white light-emitting diodes can simultaneously satisfy the color temperature and rendition requirements due to the lack of sufficient red spectral component in the phosphors’emission spectrum.Here,we report a new yellow Ba_(0.93)Eu_(0.07)Al_(2)O_(4) phosphor that has a new orthorhombic lattice structure and exhibits a broad yellow photoluminescence band with sufficient red spectral component.Warm-white emissions with correlated color temperature,4000 K and color rendering index.80 were readily achieved when combining the Ba_(0.93)Eu_(0.07)Al_(2)O_(4) phosphor with a blue light-emitting diode(440–470 nm).This study demonstrates that warm-white light-emitting diodes with high color rendition(i.e.,color rendering index.80)can be achieved based on single-phosphor,single-emitting-center conversion.
基金This work has been supported by NSFC(Grants No.10834006,51172226,61275055 and 11274007).
文摘The rare earth Er^(3+) and Yb^(3+) codoped system is the most attractive for showcasing energy transfer upconversion.This system can generate green and red emissions from Er^(3+) under infrared excitation of the sensitizer Yb^(3+).It is well known that the red-emitting state can be populated from the upper green-emitting state.The contribution of multiphonon relaxation to this population is generally considered important at low excitation densities.Here,we demonstrate for the first time the importance of a previously proposed but neglected mechanism described as a cross relaxation energy transfer from Er^(3+) to Yb^(3+),followed by an energy back transfer within the same Er^(3+)–Yb^(3+) pair.A luminescence spectroscopy study of cubic Y_(2)O_(3):Er^(3+),Yb^(3+) indicates that this mechanism can be more efficient than multiphonon relaxation,and it can even make a major contribution to the red upconversion.The study also revealed that the energy transfers involved in this mechanism take place only in the nearest Er^(3+)–Yb^(3+) pairs,and thus,it is fast and efficient at low excitation densities.Our results enable a better understanding of upconversion processes and properties in the Er^(3+)–Yb^(3+) system.
基金supported by the internal funding source from University of Shanghai for Science and Technology.
文摘Coarse columnar β grains result in anisotropic mechanical properties in Ti alloys deposited by additive manufacturing. This study reports that Ti-6Al-4V alloy fabricated by coaxial electron beam wire feeding additive manufacturing presents a weak anisotropy, high strength and ductility. The superior tensile property arises from a microstructure with fine equiaxed β grains(EGβ), discontinuous grain boundary α phase and short intragranular α lamellae. A large region of fine EGβ arises from a special combination of the temperature gradient and solidification rate, and attractive α morphology is caused by solid phase transformations during interpass thermal cycling and post heat treatments.
基金funded by Monash Centre for Additive Manufacturing (MCAM) and Australia Research CouncilIH130100008 “Industrial Transformation Research Hub for Transforming Australia’s Manufacturing Industry through High Value Additive Manufacturing”the National Natural Science Foundation of China (No. 51701124)
文摘Static coarsening mechanism of selective laser melted(SLMed) Ti–6Al–4V with a lamellar microstructure was established at temperatures from 700℃ to 950℃. Microstructure evolution revealed that high heat treatment temperature facilitated martensite decomposition and promoted lamellae growth. At each temperature, the growth rate decreased with increasing holding time. The static coarsening behaviour of SLMed Ti–6Al–4V can be interpreted by Lifshitz, Slyozov, and Wagner(LSW) theory. The coarsening coefficient were 0.33, 0.33–0.4, 0.4–0.5 for 700–800℃, 900℃ and 950℃, respectively. This indicated the coarsening mechanism was bulk diffusion at 700–800℃, and a combination of bulk diffusion and interface reaction at 900℃ and 950℃ conditions.
基金Supported by the Chinese Academy of Sciences Strategic Priority Research Program(XDA19030402)Shandong Key Research and Development Project(2018GNC110025)+2 种基金Taishan Scholar Program of Shandong Province(TSXZ201712)National Natural Science Foundation of China(31671585 and 41871253)Excellent Master Degree Dissertation Cultivation Program of Yangtze University。
文摘Analysis of the formation and evolution of urban surface thermal environment is crucial for urban planning and improving the environment of a settlement.Qingdao was selected in this study as a typical coastal city undergoing rapid urbanization,and the spatiotemporal dynamic characteristics of its urban surface thermal environment from2010 to 2019 were evaluated.The random forest(RF)algorithm was adopted to obtain its land surface temperature(LST)map with 30-m resolution by downscaling the Moderate Resolution Imaging Spectroradiometer(MODIS)LST product;the remote sensing indices emphasizing different land cover types,LST calculated by the radiative transfer equation,and elevation were used as input variables in the algorithm.The heat island intensity(HII),urban heat island(UHI)volume,and UHI grade were used to analyze the spatiotemporal dynamic characteristics of the urban surface thermal environment in Qingdao.The results show an increasing trend in average HII between 1.1 and 2.52°C in the study area over the past 10 years.The northern city appeared to have the highest UHI volume,while change of the UHI volume in Huangdao District of southwestern Qingdao was the most significant.The areas with high HII have gradually expanded during the last 10 years,and the areas with a 10-yr persistently high HII are distributed mainly in old urban areas with high building density and a dense population.Different factors may influence UHI,such as artificial heat sources,surface heat sources,and hybrid heat sources.Finally,adjusting the urban structure,increasing the vegetated area,and changing building colors are proposed to mitigate UHI in the areas with continuously high HII.
基金This work was supported by the CAS Strategic Priority Research CAS[No.XDA19030402]National Natural Science Foundation of China[31671585,41871253]+1 种基金This work was funded by the CAS Strategic Priority Research Program(No.XDA19030402)the National Natural Science Foundation of China(No.31671585,41871253).
文摘Evapotranspiration(ET)is a pivotal process for ecosystem water budgets and accounts for a substantial portion of the global energy balance.In this paper,the exited actual ETmain datasets in global scale,and the global ET modeling and estimates were focused on discussion.The Source energy balance(SEB)models,empirical models and other process-based models are summarized.Accuracy for ET estimates by SEBmodels highly depends on accurate surface temperature retrieval,and SEB models are hard to apply in large heterogeneous surface.The Penman-Monteith(PM)equations are thought to be with considerable sound mechanism.However,it involves large number of parameters,which are not all global available.A simplified PM equation by Priestley and Taylor(PT)is found to perform well on well-watered surface.For both PM and PT equations in estimating ET,the key is to consider the constraint from surface resistance primarily water stress.Empiricalmodels are simple but the accuracy of which highly depends on training samples.Coupling satellite data into ET models can improve ET estimates with higher resolution spatiotemporal information inputs;However,finding the most proper way to estimate global ET remains problematic.Several reasons for this issue are also analyzed in this review.
文摘Land use change can have a strong impact on soil carbon dynamics and carbon stocks in urban areas. Due to rapid urbanization, large areas of land have been paved, and other areas have undergone rapid land use change. Evaluation of the impact of urbanization on carbon dynamics and carbon stock （30 cm） has become an issue of urgent concern. The soil carbon dynamics, due to rapid land use change in Tianjin Binhai New Area of China, have been simulated in this paper using the RothC model. Because this area is saline, a modified version of RothC that includes a salt rate modifier provided more accurate simulations than the original model. The conversion to urban green land was not accurately simulated by either of the models because of the undefined changes in soil and plant conditions. According to the model, changes of arable to grassland resulted in a decline in soil carbon stocks, and changes of grassland to forest and grassland to arable resulted in increased soil carbon stocks in this area. Across the whole area simulated, the total carbon stocks in 2010 had decreased due to land use change by 6.5% from the 1979 value. By 2050, a further decrease of 21.9% is expected according to the 2050 plan for land use and the continuing losses from the soils due to previous land use changes.
基金Project supported by the Zhejiang Provincial Natural Science Foundation of China(No.LY17F040001)the Open Project Program of Surface Physics Laboratory(National Key Laboratory)of Fudan University(No.KF2015_02)+2 种基金the Open Project Program of National Laboratory for Infrared Physics,Chinese Academy of Sciences(No.M201503)the Zhejiang Provincial Science and Technology Key Innovation Team(No.2011R50012)the Zhejiang Provincial Key Laboratory(No.2013E10022)
文摘The influence of oxygen doping on resistive-switching characteristics of Ag/a-Si/p^＋-c-Si device was investigated. By oxygen doping in the growth process of amorphous silicon, the device resistive-switching performances, such as the ON/OFF resistance ratios, yield and stability were improved, which may be ascribed to the significant reduction of defect density because of oxygen incorporation. The device I-V characteristics are strongly dependent on the oxygen doping concentration. As the oxygen doping concentration increases, the Si-rich device gradually transforms to an oxygen-rich device, and the device yield, switching characteristics, and stability may be improved for silver/oxygen-doped a-Si/p^＋-c-Si device. Finally, the device resistive-switching mechanism was ana- lyzed. Key words： amorphous silicon; resistive switching; oxygen doping
