The Northeast China cold vortex(NCCV)during late summer(from July to August)is identified and classified into three types in terms of its movement path using machine learning.The relationships of the three types of NC...The Northeast China cold vortex(NCCV)during late summer(from July to August)is identified and classified into three types in terms of its movement path using machine learning.The relationships of the three types of NCCV intensity with atmospheric circulations in late summer,the sea surface temperature(SST),and Arctic sea ice concentration(SIC)in the preceding months,are analyzed.The sensitivity tests by the Community Atmosphere Model version 5.3(CAM5.3)are used to verify the statistical results.The results show that the coordination pattern of East Asia-Pacific(EAP)and Lake Baikal high pressure forced by SST anomalies in the North Indian Ocean dipole mode(NIOD)during the preceding April and SIC anomalies in the Nansen Basin during the preceding June results in an intensity anomaly for the first type of NCCV.While the pattern of high pressure over the Urals and Okhotsk Sea and low pressure over Lake Baikal during late summer-which is forced by SST anomalies in the South Indian Ocean dipole mode(SIOD)in the preceding June and SIC anomalies in the Barents Sea in the preceding April-causes the intensity anomaly of the second type.The third type is atypical and is not analyzed in detail.Sensitivity tests,jointly forced by the SST and SIC in the preceding period,can well reproduce the observations.In contrast,the results forced separately by the SST and SIC are poor,indicating that the NCCV during late summer is likely influenced by the coordinated effects of both SST and SIC in the preceding months.展开更多
Fe/Co-based diatomic catalysts decorated on an N-doped graphene substrate are investigated by first-principles calculations to improve the electrochemical properties of Li–S batteries.Our results demonstrate that Fe ...Fe/Co-based diatomic catalysts decorated on an N-doped graphene substrate are investigated by first-principles calculations to improve the electrochemical properties of Li–S batteries.Our results demonstrate that Fe CoN8@Gra not only possesses moderate adsorption energies towards Li2Snspecies,but also exhibits superior catalytic activity for both reduction and oxidation reactions of the sulfur cathode.Moreover,the metallic property of the diatomic catalysts can be well maintained after Li2Snadsorption,which could help the sulfur cathode to maintain high conductivity during the whole charge–discharge process.Given these exceptional properties,it is expected that Fe CoN8@Gra could be a promising diatomic catalyst for Li–S batteries and afford insights for further development of advanced Li–S batteries.展开更多
The classification of the Northeast China Cold Vortex(NCCV)activity paths is an important way to analyze its characteristics in detail.Based on the daily precipitation data of the northeastern China(NEC)region,and the...The classification of the Northeast China Cold Vortex(NCCV)activity paths is an important way to analyze its characteristics in detail.Based on the daily precipitation data of the northeastern China(NEC)region,and the atmospheric circulation field and temperature field data of ERA-Interim for every six hours,the NCCV processes during the early summer(June)seasons from 1979 to 2018 were objectively identified.Then,the NCCV processes were classified using a machine learning method(k-means)according to the characteristic parameters of the activity path information.The rationality of the classification results was verified from two aspects,as follows:(1)the atmospheric circulation configuration of the NCCV on various paths;and(2)its influences on the climate conditions in the NEC.The obtained results showed that the activity paths of the NCCV could be divided into four types according to such characteristics as the generation origin,movement direction,and movement velocity of the NCCV.These included the generation-eastward movement type in the east of the Mongolia Plateau(eastward movement type or type A);generation-southeast longdistance movement type in the upstream of the Lena River(southeast long-distance movement type or type B);generationeastward less-movement type near Lake Baikal(eastward less-movement type or type C);and the generation-southward less-movement type in eastern Siberia(southward less-movement type or type D).There were obvious differences observed in the atmospheric circulation configuration and the climate impact of the NCCV on the four above-mentioned types of paths,which indicated that the classification results were reasonable.展开更多
This paper studies self-synchronization and stability of a dual-motor driven vibration system with a two-stage vibration isolation frame. Oscillation amplitude of the material box large enough can be ensured on the vi...This paper studies self-synchronization and stability of a dual-motor driven vibration system with a two-stage vibration isolation frame. Oscillation amplitude of the material box large enough can be ensured on the vibration system in order to screen materials. Reduction of the dynamic load transmitted to the foundation can also be achieved for the vibration system. A Lagrange equation is used to set up the motion differential equations of the system, and a dimensionless coupled equation of the eccentric rotors is obtained using a method of modified average small parameter. According to the existence condition of zero solution in the dimensionless coupled equation of the eccentric rotors, the precondition for commencing self-synchronization motion is achieved.The stability condition of self-synchronization is obtained based on the Routh-Hurwitz criterion. The theoretical analysis is validated by simulations and experiments.展开更多
[Objective]The study aimed to discuss the influence of light and temperature factors on biomass accumulation of winter wheat at each growth stage and changes in biomass of each organ.[Method]Based on the observation d...[Objective]The study aimed to discuss the influence of light and temperature factors on biomass accumulation of winter wheat at each growth stage and changes in biomass of each organ.[Method]Based on the observation data from Xifeng Agrometeorological Experiment Station of Gansu Province,including phenophase and yield factors of winter wheat in 1981-2008,biomass at three-leaves,overwintering,jointing,heading,milky maturity,and maturity stages in 1995-2008,and meteorological data in 1995-2008,the variation patterns of the biomass accumulation and the influence of TEP(thermal effectiveness photosynthetically active radiation)on the biomass of winter wheat at every growth stage were analyzed.[Result]The biomass accumulation of winter wheat in the whole growth period presented"S"curve,with the maximum value from heading to milky maturity stage.Since 1981,TEP from heading to milky maturity stage increased with a rate of 3.314 MJ/(m2·a),and the changing curves of TEP at other stages were like parable curves.TEP from turning green to jointing stage and from milky maturity to maturity stage had a higher value in the 1990s and a lower value in the 1980s and early 21stcentury,while that from jointing to heading stage had a lower value in the1990s but a higher value in the 1980s and early 21stcentury.There was a significant correlation between TEP at each growth stage and the actual yield.LAI(leaf area index)at each development stage also had a significant correlation with the utilization rate of TEP at corresponding stage.When LAI at jointing and heading stages increased by 1,the utilization rate of TEP correspondingly increased by 0.049 and 0.259 g/MJ respectively.[Conclusion]The research could provide theoretical references for the scientific planting and management of winter wheat in future.展开更多
By using data of hourly rainfall with all of the meteorological stations in the upper reaches of Hunhe River (Qingyuan Section), the digital elevation model, the land use and the disasters data etc., the storm flood p...By using data of hourly rainfall with all of the meteorological stations in the upper reaches of Hunhe River (Qingyuan Section), the digital elevation model, the land use and the disasters data etc., the storm flood process which happened on 16 August 2013 is reproduced simulated based on the rainstorm flooding of FloodArea model, also the flooding simulation and its effectiveness have been carried out. Conclusions are drawn as follows: there is a sharp rise of the flood depth falling behind the change of rainfall three or four hours. As the accumulation of the precipitation, the water level has increased, and when the precipitation process stops, the flood pooled into midstream and downstream gradually. According to the disaster investigation, in both the aspects of flooding scope and flooding depth of warning spots, the simulation result of FloodArea model agrees with the fact. It indicates that the FloodArea model generates good simulation effect in the upper reaches of Hunhe River (Qingyuan Section). Combined with population and GDP information, in the whole river, about eighty-three thousand people were affected by flooding, also one billion and five hundred seventy five million RMB of gross domestic product was lost. When the flood depth deepens and the flooding scope increases, correspondingly the loss rate of population and GDP rises and the flood risk increases.展开更多
Based on the meteorological and geographic information data, with statistical method and the FloodArea model, the extreme daily rainfall of the 100-year return period in Hunhe River basin was established, through the ...Based on the meteorological and geographic information data, with statistical method and the FloodArea model, the extreme daily rainfall of the 100-year return period in Hunhe River basin was established, through the simulation of rainstorm and flood disaster, characteristics of flood depth in warning spot Cangshi village in the upstream of the river were analysed, and possible effect on community economy was also evaluated. Results showed that, the precipitation of 100-year return period occurred, the flood depth has been below 1.0 meter in the most areas of Hunhe River basin, the depth was between 1.0 meter and 2.5 meters in the part areas of Hunhe River basin, and the flood depth has been exceed 2.5 meters in a small part of Hunhe River basin. After the beginning of precipitation, the flood was concentrated in the upper reaches of the river. With the accumulation of precipitation and the passage of time, the flood pools into midstream and downstream. Precipitation lasted for 24 hours, the warning spot was flooded in the beginning of precipitation. With the accumulation of precipitation, water level of the river increases gradually. The depth of warning spot has passed 1.0 meter at the 07 time of the whole process, and the maximum value of flood depth at warning spot was 1.083 meters that occurred at the 19 time. The flood depth of warning spot decreased gradually after the precipitation stopping, and the depth has been below 0.2 meters, the flood of upstream ended. Up to the end of the upstream flood process, in the whole river, about one million five hundred and sixty thousand people were affected by flooding, and thirty-eight billion and two hundred million RMB of gross domestic product were lost, in addition, dry land and paddy field were affected greatly, but woodland and grassland were less affected.展开更多
With the development and application of artificial intelligence(AI)technology,it has promoted the upgrading and development of the industry.However,AI also brings intangible impact to the actual survival of human bein...With the development and application of artificial intelligence(AI)technology,it has promoted the upgrading and development of the industry.However,AI also brings intangible impact to the actual survival of human beings.Stephen·Hawking,the renowned physicist,has repeatedly warned,making it all the more urgent to reflect on the negative effects of artificial intelligence.Therefore,the review of AI should consider from the perspective of historical development,scientifically explain its changes in the way of human labor and social life,as well as the great significance of such changes to the liberation of human labor.展开更多
Nanomedicine has become an important development direction of modern medicine, and provides a new way for cancer theranostics. To extend the superior physicochemical property of nanomedicine and enhance their role in ...Nanomedicine has become an important development direction of modern medicine, and provides a new way for cancer theranostics. To extend the superior physicochemical property of nanomedicine and enhance their role in cancer theranostics,various strategies have been proposed. Among them, the introduction of oxygen vacancies can enhance the separation of electron-hole pairs and improve the nanomaterials' catalytic activity, which is beneficial for cancer diagnosis and treatment. This review briefly summarized the formation mechanism and preparation methods of various oxygen vacancy nanomaterials. Then,the effect and application of various oxygen vacancy nanomaterials, such as iron, manganese, titanium, zinc, bismuth, tungsten,cerium, and molybdenum-based nanomaterials in enhancing cancer theranostics were highlighted. At last, the prospect and challenges of oxygen vacancy nanomaterials were discussed. This review provided an overview of the relevant information on oxygen vacancy in cancer theranostics, and further promoted the development of cancer nanomedicine.展开更多
There is an accumulating body of evidence implicating the muscarinic acetylcholine receptor4(M4)in schizophrenia and dementia with Lewy bodies,however,a clinically validated M4positron emission tomography(PET)radiolig...There is an accumulating body of evidence implicating the muscarinic acetylcholine receptor4(M4)in schizophrenia and dementia with Lewy bodies,however,a clinically validated M4positron emission tomography(PET)radioligand is currently lacking.As such,the aim of this study was to develop a suitable M4PET ligand that allows the non-invasive visualization of M4in the brain.Structure-activity relationship studies of pyrazol-4-yl-pyridine derivates led to the discovery of target compound 12—a subtype-selective positive allosteric modulator(PAM).The radiofluorinated analogue,[18F]12,was synthesized in 28±10%radiochemical yield,>37 GBq/μmol and an excellent radiochemical purity>99%.Initial in vitro autoradiograms on rodent brain sections were performed in the absence of carbachol and showed moderate specificity as well as a low selectivity of[18F]12 for the M4-rich striatum.However,in the presence of carbachol,a significant increase in tracer binding was observed in the rat striatum,which was reduced by>60%under blocking conditions,thus indicating that orthosteric ligand interaction is required for efficient binding o f[18F]12 to the allosteric site.Remarkably,however,the presence of carbachol was not required for high specific binding in the non-human primate(NHP)and human striatum,and did not further improve the specificity and selectivity of[18F]12 in higher species.These results pointed towards significant species-differences and paved the way for a preliminary PET study in NHP,where peak brain uptake of[18F]12 was found in the putamen and temporal cortex.In conclusion,we report on the identification and preclinical development of the first radiofluorinated M4PET radioligand with promising attributes.The availability of a clinically validated M4PET radioligand harbors potential to facilitate drug development and provide a useful diagnostic tool for non-invasive imaging.展开更多
Gallium nitride(Ga N)-based light-emitting diodes(LEDs)are important for lighting and display applications.In this paper,we demonstrate green-emission(512 nm)In Ga N quantum dot(QD)LEDs grown on a c-plane sapphire sub...Gallium nitride(Ga N)-based light-emitting diodes(LEDs)are important for lighting and display applications.In this paper,we demonstrate green-emission(512 nm)In Ga N quantum dot(QD)LEDs grown on a c-plane sapphire substrate by metal-organic chemical vapor deposition.A radiative lifetime of 707 ps for the uniform In Ga N self-assembled QDs is obtained by time-resolved photoluminescence measurement at 18 K.The screening of the built-in fields in the QDs effectively improves the performance of QD LEDs.These high quantum efficiency and high temperature stability green QD LEDs are able to operate with negligible efficiency droop and with current density up to 106 A∕cm^2.Our results show that In Ga N QDs may be a viable option as the active medium for stable LEDs.展开更多
Based on summer precipitation hindcasts for 1991–2013 produced by the Beijing Climate Center Climate System Model(BCC_CSM), the relationship between precipitation prediction error in northeastern China(NEC) and globa...Based on summer precipitation hindcasts for 1991–2013 produced by the Beijing Climate Center Climate System Model(BCC_CSM), the relationship between precipitation prediction error in northeastern China(NEC) and global sea surface temperature is analyzed, and dynamic–analogue prediction is carried out to improve the summer precipitation prediction skill of BCC_CSM, through taking care of model historical analogue prediction error in the real-time output. Seven correction schemes such as the systematic bias correction, pure statistical correction, dynamic–analogue correction, and so on, are designed and compared. Independent hindcast results show that the 5-yr average anomaly correlation coefficient(ACC) of summer precipitation is respectively improved from –0.13/0.15 to 0.16/0.24 for 2009–13/1991–95 when using the equally weighted dynamic–analogue correction in the BCC_CSM prediction,which takes the arithmetical mean of the correction based on regional average error and that on grid point error. In addition, probabilistic prediction using the results from the multiple correction schemes is also performed and it leads to further improved 5-yr average prediction accuracy.展开更多
As a member of cyclic nucleotide phosphodiesterase(PDE)enzyme family,PDE10A is in charge of the degradation of cyclic adenosine(cAMP)and guanosine monophosphates(cGMP).While PDE10A is primarily expressed in the medium...As a member of cyclic nucleotide phosphodiesterase(PDE)enzyme family,PDE10A is in charge of the degradation of cyclic adenosine(cAMP)and guanosine monophosphates(cGMP).While PDE10A is primarily expressed in the medium spiny neurons of the striatum,it has been implicated in a variety of neurological disorders.Indeed,inhibition of PDE10A has proven to be of potential use for the treatment of central nervous system(CNS)pathologies caused by dysfunction of the basal ganglia–of which the striatum constitutes the largest component.A PDE10A-targeted positron emission tomography(PET)radioligand would enable a better assessment of the pathophysiologic role of PDE10A,as well as confirm the relationship between target occupancy and administrated dose of a given drug candidate,thus accelerating the development of effective PDE10A inhibitors.In this study,we designed and synthesized a novel ^(18)F-aryl PDE10A PET radioligand,codenamed[^(18)F]P10A-1910([^(18)F]9),in high radiochemical yield and molar activity via spirocyclic iodonium ylide-mediated radiofluorination.[^(18)F]9 possessed good in vitro binding affinity(IC_(50)=2.1 nmol/L)and selectivity towards PDE10A.Further,[^(18)F]9 exhibited reasonable lipophilicity(logD=3.50)and brain permeability(P_(app)>10×10^(−6) cm/s in MDCK-MDR1 cells).PET imaging studies of[^(18)F]9 revealed high striatal uptake and excellent in vivo specificity with reversible tracer kinetics.Preclinical studies in rodents revealed an improved plasma and brain stability of[^(18)F]9 when compared to the current reference standard for PDE10A-targeted PET,[^(18)F]MNI659.Further,dose–response experiments with a series of escalating doses of PDE10A inhibitor 1 in rhesus monkey brains confirmed the utility of[^(18)F]9 for evaluating target occupancy in vivo in higher species.In conclusion,our results indicated that[^(18)F]9 is a promising PDE10A PET radioligand for clinical translation.展开更多
Based on the ground surface temperature(GST)and snow surface temperature(SST)measurements during the period of adjustment from manual to automatic observation systems in China,the influence of observation methods on G...Based on the ground surface temperature(GST)and snow surface temperature(SST)measurements during the period of adjustment from manual to automatic observation systems in China,the influence of observation methods on GST and its relationship with snow cover is analyzed.GST is corrected by SST,and the correction effect is evaluated.The results show that,during the parallel observation period,the winter GSTs from automatic observations are generally higher than those from manual observations,with the automatically observed national daily GST 1.18°C higher.The adjustment has a greater impact on GSTs at 0200,0800,and 2000 Beijing Time(BT)than at 1400 BT,and it has the greatest impact in Northeast and Northwest China,with deviations of 5.24 and 2.09°C,respectively.The GST deviation is closely related to the snow depth and annual snow totals.The average daily GST deviation increases at the rate of 0.66°C per 1-cm increase of snow depth when it is<15 cm,while it tends to be stable at around 10°C for snow depth over 15 cm.The GST deviation at a station is affected by its winter snow totals in Northeast and Northwest China,where the largest deviations are found where snow totals are all above 1000 cm.After the correction with SST,the mean deviation between the automatic and manual observations as well as the false trend can be effectively reduced.Following the correction,the mean deviation of daily GST decreases by 5.8°C,and its trend decreases from 1.87 to 0.65°C decade-1.展开更多
Chemical systems that can replicate cellular behaviors are gaining increasing attention and are being used to study various biological processes.Here,a protein-or amylose-based assembly at an oil/water interface was e...Chemical systems that can replicate cellular behaviors are gaining increasing attention and are being used to study various biological processes.Here,a protein-or amylose-based assembly at an oil/water interface was employed to construct a large compartmentalized adipocyte-like structure,and a lipid droplet-like microcompartment(amylose-polymerstabilized 2-ethyl-1-hexanol microcompartment),which exhibits floating behaviors driven by the amylose-polymer micelle solubilization,was introduced inside these adipocyte-like structures.When the lipase-based catalytic reaction and the external oil composition were controlled and another lipid droplet-like microcompartment(lipase-stabilized tributyrin microcompartment)was introduced,then a series of dynamic behaviors were exhibited by the two types of lipid droplet-like microcompartments,including growth,self-sorting,and fusion within the adipocyte-like structures.Therefore,it is anticipated that this autonomous generation of hierarchical multicompartments represents a breakthrough compared to the traditional bottom-up strategies,and the artificial life systems we studied could contribute a chemical-based strategy of understanding the process of lipid droplet growth and fusion inside a living adipocyte cell.展开更多
基金jointly supported by the National Natural Science Foundation of China (Grant No. 42005037)Special Project of Innovative Development, CMA (CXFZ2021J022, CXFZ2022J008, and CXFZ2021J028)+1 种基金Liaoning Provincial Natural Science Foundation Project (Ph.D. Start-up Research Fund 2019-BS214)Research Project of the Institute of Atmospheric Environment, CMA (2021SYIAEKFMS08, 2020SYIAE08 and 2021SYIAEKFMS09)
文摘The Northeast China cold vortex(NCCV)during late summer(from July to August)is identified and classified into three types in terms of its movement path using machine learning.The relationships of the three types of NCCV intensity with atmospheric circulations in late summer,the sea surface temperature(SST),and Arctic sea ice concentration(SIC)in the preceding months,are analyzed.The sensitivity tests by the Community Atmosphere Model version 5.3(CAM5.3)are used to verify the statistical results.The results show that the coordination pattern of East Asia-Pacific(EAP)and Lake Baikal high pressure forced by SST anomalies in the North Indian Ocean dipole mode(NIOD)during the preceding April and SIC anomalies in the Nansen Basin during the preceding June results in an intensity anomaly for the first type of NCCV.While the pattern of high pressure over the Urals and Okhotsk Sea and low pressure over Lake Baikal during late summer-which is forced by SST anomalies in the South Indian Ocean dipole mode(SIOD)in the preceding June and SIC anomalies in the Barents Sea in the preceding April-causes the intensity anomaly of the second type.The third type is atypical and is not analyzed in detail.Sensitivity tests,jointly forced by the SST and SIC in the preceding period,can well reproduce the observations.In contrast,the results forced separately by the SST and SIC are poor,indicating that the NCCV during late summer is likely influenced by the coordinated effects of both SST and SIC in the preceding months.
基金the National Natural Science Foundation of China(Grant Nos.51972140 and 51903164)the Fund from Science and Technology Department of Jilin Province,China(Grant No.20200201069JC).
文摘Fe/Co-based diatomic catalysts decorated on an N-doped graphene substrate are investigated by first-principles calculations to improve the electrochemical properties of Li–S batteries.Our results demonstrate that Fe CoN8@Gra not only possesses moderate adsorption energies towards Li2Snspecies,but also exhibits superior catalytic activity for both reduction and oxidation reactions of the sulfur cathode.Moreover,the metallic property of the diatomic catalysts can be well maintained after Li2Snadsorption,which could help the sulfur cathode to maintain high conductivity during the whole charge–discharge process.Given these exceptional properties,it is expected that Fe CoN8@Gra could be a promising diatomic catalyst for Li–S batteries and afford insights for further development of advanced Li–S batteries.
基金supported by Liaoning Province College Science and Research(2008S095)the Key Project of the National Natural Science Foundation of China(50535010,50805020)High-tech Research and Development Program of China(2007AA04Z442)
基金This research was jointly supported by the National Natural Science Foundation of China(Grant No.42005037)the Liaoning Provincial Natural Science Foundation Project(PhD Start-up Research Fund 2019-BS-214),the Special Scientific Research Project for the Forecaster(Grant No.CMAYBY2018-018)+2 种基金a Key Technical Project of Liaoning Meteorological Bureau(Grant No.LNGJ201903)the National Key Research and Development Project(Grant No.2018YFC1505601)the Open Foundation Project of the Institute of Atmospheric Environment,China Meteorological Administration(Grant Nos.2020SYIAE08 and 2020SYIAEZD5).
文摘The classification of the Northeast China Cold Vortex(NCCV)activity paths is an important way to analyze its characteristics in detail.Based on the daily precipitation data of the northeastern China(NEC)region,and the atmospheric circulation field and temperature field data of ERA-Interim for every six hours,the NCCV processes during the early summer(June)seasons from 1979 to 2018 were objectively identified.Then,the NCCV processes were classified using a machine learning method(k-means)according to the characteristic parameters of the activity path information.The rationality of the classification results was verified from two aspects,as follows:(1)the atmospheric circulation configuration of the NCCV on various paths;and(2)its influences on the climate conditions in the NEC.The obtained results showed that the activity paths of the NCCV could be divided into four types according to such characteristics as the generation origin,movement direction,and movement velocity of the NCCV.These included the generation-eastward movement type in the east of the Mongolia Plateau(eastward movement type or type A);generation-southeast longdistance movement type in the upstream of the Lena River(southeast long-distance movement type or type B);generationeastward less-movement type near Lake Baikal(eastward less-movement type or type C);and the generation-southward less-movement type in eastern Siberia(southward less-movement type or type D).There were obvious differences observed in the atmospheric circulation configuration and the climate impact of the NCCV on the four above-mentioned types of paths,which indicated that the classification results were reasonable.
基金Project supported by the National Natural Science Foundation of China(No.51175071)the Fundamental Research Funds for the Central Universities(Nos.N120203001 and N130803001)the National Key Scientific Instrument and Equipment Development Projects(No.2013YQ474765)
文摘This paper studies self-synchronization and stability of a dual-motor driven vibration system with a two-stage vibration isolation frame. Oscillation amplitude of the material box large enough can be ensured on the vibration system in order to screen materials. Reduction of the dynamic load transmitted to the foundation can also be achieved for the vibration system. A Lagrange equation is used to set up the motion differential equations of the system, and a dimensionless coupled equation of the eccentric rotors is obtained using a method of modified average small parameter. According to the existence condition of zero solution in the dimensionless coupled equation of the eccentric rotors, the precondition for commencing self-synchronization motion is achieved.The stability condition of self-synchronization is obtained based on the Routh-Hurwitz criterion. The theoretical analysis is validated by simulations and experiments.
基金Supported by the Arid Meteorology Foundation of Institute of Arid Meteorology,China Meteorological Administration(IAM200803)
文摘[Objective]The study aimed to discuss the influence of light and temperature factors on biomass accumulation of winter wheat at each growth stage and changes in biomass of each organ.[Method]Based on the observation data from Xifeng Agrometeorological Experiment Station of Gansu Province,including phenophase and yield factors of winter wheat in 1981-2008,biomass at three-leaves,overwintering,jointing,heading,milky maturity,and maturity stages in 1995-2008,and meteorological data in 1995-2008,the variation patterns of the biomass accumulation and the influence of TEP(thermal effectiveness photosynthetically active radiation)on the biomass of winter wheat at every growth stage were analyzed.[Result]The biomass accumulation of winter wheat in the whole growth period presented"S"curve,with the maximum value from heading to milky maturity stage.Since 1981,TEP from heading to milky maturity stage increased with a rate of 3.314 MJ/(m2·a),and the changing curves of TEP at other stages were like parable curves.TEP from turning green to jointing stage and from milky maturity to maturity stage had a higher value in the 1990s and a lower value in the 1980s and early 21stcentury,while that from jointing to heading stage had a lower value in the1990s but a higher value in the 1980s and early 21stcentury.There was a significant correlation between TEP at each growth stage and the actual yield.LAI(leaf area index)at each development stage also had a significant correlation with the utilization rate of TEP at corresponding stage.When LAI at jointing and heading stages increased by 1,the utilization rate of TEP correspondingly increased by 0.049 and 0.259 g/MJ respectively.[Conclusion]The research could provide theoretical references for the scientific planting and management of winter wheat in future.
文摘By using data of hourly rainfall with all of the meteorological stations in the upper reaches of Hunhe River (Qingyuan Section), the digital elevation model, the land use and the disasters data etc., the storm flood process which happened on 16 August 2013 is reproduced simulated based on the rainstorm flooding of FloodArea model, also the flooding simulation and its effectiveness have been carried out. Conclusions are drawn as follows: there is a sharp rise of the flood depth falling behind the change of rainfall three or four hours. As the accumulation of the precipitation, the water level has increased, and when the precipitation process stops, the flood pooled into midstream and downstream gradually. According to the disaster investigation, in both the aspects of flooding scope and flooding depth of warning spots, the simulation result of FloodArea model agrees with the fact. It indicates that the FloodArea model generates good simulation effect in the upper reaches of Hunhe River (Qingyuan Section). Combined with population and GDP information, in the whole river, about eighty-three thousand people were affected by flooding, also one billion and five hundred seventy five million RMB of gross domestic product was lost. When the flood depth deepens and the flooding scope increases, correspondingly the loss rate of population and GDP rises and the flood risk increases.
文摘Based on the meteorological and geographic information data, with statistical method and the FloodArea model, the extreme daily rainfall of the 100-year return period in Hunhe River basin was established, through the simulation of rainstorm and flood disaster, characteristics of flood depth in warning spot Cangshi village in the upstream of the river were analysed, and possible effect on community economy was also evaluated. Results showed that, the precipitation of 100-year return period occurred, the flood depth has been below 1.0 meter in the most areas of Hunhe River basin, the depth was between 1.0 meter and 2.5 meters in the part areas of Hunhe River basin, and the flood depth has been exceed 2.5 meters in a small part of Hunhe River basin. After the beginning of precipitation, the flood was concentrated in the upper reaches of the river. With the accumulation of precipitation and the passage of time, the flood pools into midstream and downstream. Precipitation lasted for 24 hours, the warning spot was flooded in the beginning of precipitation. With the accumulation of precipitation, water level of the river increases gradually. The depth of warning spot has passed 1.0 meter at the 07 time of the whole process, and the maximum value of flood depth at warning spot was 1.083 meters that occurred at the 19 time. The flood depth of warning spot decreased gradually after the precipitation stopping, and the depth has been below 0.2 meters, the flood of upstream ended. Up to the end of the upstream flood process, in the whole river, about one million five hundred and sixty thousand people were affected by flooding, and thirty-eight billion and two hundred million RMB of gross domestic product were lost, in addition, dry land and paddy field were affected greatly, but woodland and grassland were less affected.
文摘With the development and application of artificial intelligence(AI)technology,it has promoted the upgrading and development of the industry.However,AI also brings intangible impact to the actual survival of human beings.Stephen·Hawking,the renowned physicist,has repeatedly warned,making it all the more urgent to reflect on the negative effects of artificial intelligence.Therefore,the review of AI should consider from the perspective of historical development,scientifically explain its changes in the way of human labor and social life,as well as the great significance of such changes to the liberation of human labor.
基金supported by the National Natural Science Foundation of China (22104073)the Natural Science Foundation of Shandong (ZR2021QB119, 2022HWYQ-079)the Youth Innovation Science and Technology Program of Shandong Provincial Universities (2021KJ100)。
文摘Nanomedicine has become an important development direction of modern medicine, and provides a new way for cancer theranostics. To extend the superior physicochemical property of nanomedicine and enhance their role in cancer theranostics,various strategies have been proposed. Among them, the introduction of oxygen vacancies can enhance the separation of electron-hole pairs and improve the nanomaterials' catalytic activity, which is beneficial for cancer diagnosis and treatment. This review briefly summarized the formation mechanism and preparation methods of various oxygen vacancy nanomaterials. Then,the effect and application of various oxygen vacancy nanomaterials, such as iron, manganese, titanium, zinc, bismuth, tungsten,cerium, and molybdenum-based nanomaterials in enhancing cancer theranostics were highlighted. At last, the prospect and challenges of oxygen vacancy nanomaterials were discussed. This review provided an overview of the relevant information on oxygen vacancy in cancer theranostics, and further promoted the development of cancer nanomedicine.
基金supported by the Swiss National Science Foundation(SNSF)supported by the National Health and Medical Research Council(NHMRC)Program Grant(APP1055134,USA)+1 种基金the Australian Research Council(ARC)Discovery Project(DP190102950,USA)supported by grants from Fulbright Denmark,The Lundbeck Foundation,Eva and Henry Frònkels foundation,The Danish Cancer Society,The Harboe Foundation。
文摘There is an accumulating body of evidence implicating the muscarinic acetylcholine receptor4(M4)in schizophrenia and dementia with Lewy bodies,however,a clinically validated M4positron emission tomography(PET)radioligand is currently lacking.As such,the aim of this study was to develop a suitable M4PET ligand that allows the non-invasive visualization of M4in the brain.Structure-activity relationship studies of pyrazol-4-yl-pyridine derivates led to the discovery of target compound 12—a subtype-selective positive allosteric modulator(PAM).The radiofluorinated analogue,[18F]12,was synthesized in 28±10%radiochemical yield,>37 GBq/μmol and an excellent radiochemical purity>99%.Initial in vitro autoradiograms on rodent brain sections were performed in the absence of carbachol and showed moderate specificity as well as a low selectivity of[18F]12 for the M4-rich striatum.However,in the presence of carbachol,a significant increase in tracer binding was observed in the rat striatum,which was reduced by>60%under blocking conditions,thus indicating that orthosteric ligand interaction is required for efficient binding o f[18F]12 to the allosteric site.Remarkably,however,the presence of carbachol was not required for high specific binding in the non-human primate(NHP)and human striatum,and did not further improve the specificity and selectivity of[18F]12 in higher species.These results pointed towards significant species-differences and paved the way for a preliminary PET study in NHP,where peak brain uptake of[18F]12 was found in the putamen and temporal cortex.In conclusion,we report on the identification and preclinical development of the first radiofluorinated M4PET radioligand with promising attributes.The availability of a clinically validated M4PET radioligand harbors potential to facilitate drug development and provide a useful diagnostic tool for non-invasive imaging.
文摘Gallium nitride(Ga N)-based light-emitting diodes(LEDs)are important for lighting and display applications.In this paper,we demonstrate green-emission(512 nm)In Ga N quantum dot(QD)LEDs grown on a c-plane sapphire substrate by metal-organic chemical vapor deposition.A radiative lifetime of 707 ps for the uniform In Ga N self-assembled QDs is obtained by time-resolved photoluminescence measurement at 18 K.The screening of the built-in fields in the QDs effectively improves the performance of QD LEDs.These high quantum efficiency and high temperature stability green QD LEDs are able to operate with negligible efficiency droop and with current density up to 106 A∕cm^2.Our results show that In Ga N QDs may be a viable option as the active medium for stable LEDs.
基金Supported by the Science and Technology Research Project of Liaoning Provincial Meteorological Bureau(201502)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)+1 种基金Liaoning Province Agricultural Research and Industrialization Project(2015103038)China Meteorological Administration Special Public Welfare Research(GYHY201306021)
文摘Based on summer precipitation hindcasts for 1991–2013 produced by the Beijing Climate Center Climate System Model(BCC_CSM), the relationship between precipitation prediction error in northeastern China(NEC) and global sea surface temperature is analyzed, and dynamic–analogue prediction is carried out to improve the summer precipitation prediction skill of BCC_CSM, through taking care of model historical analogue prediction error in the real-time output. Seven correction schemes such as the systematic bias correction, pure statistical correction, dynamic–analogue correction, and so on, are designed and compared. Independent hindcast results show that the 5-yr average anomaly correlation coefficient(ACC) of summer precipitation is respectively improved from –0.13/0.15 to 0.16/0.24 for 2009–13/1991–95 when using the equally weighted dynamic–analogue correction in the BCC_CSM prediction,which takes the arithmetical mean of the correction based on regional average error and that on grid point error. In addition, probabilistic prediction using the results from the multiple correction schemes is also performed and it leads to further improved 5-yr average prediction accuracy.
基金the support of K.C.Wong Education Foundation (China)financially supported by the National Natural Science Foundation of China (No.82071974)+3 种基金Shenzhen Basic Research Project (JCYJ20180503182116931, China)Guangdong Basic and Applied Basic Research Foundation (2020A1515011192, 2018A0303130052, China)Guangzhou Key Research Program on Brain Science (202007030008, China)the Fundamental Research Funds for the Central Universities (21619104, 21621051, China)
文摘As a member of cyclic nucleotide phosphodiesterase(PDE)enzyme family,PDE10A is in charge of the degradation of cyclic adenosine(cAMP)and guanosine monophosphates(cGMP).While PDE10A is primarily expressed in the medium spiny neurons of the striatum,it has been implicated in a variety of neurological disorders.Indeed,inhibition of PDE10A has proven to be of potential use for the treatment of central nervous system(CNS)pathologies caused by dysfunction of the basal ganglia–of which the striatum constitutes the largest component.A PDE10A-targeted positron emission tomography(PET)radioligand would enable a better assessment of the pathophysiologic role of PDE10A,as well as confirm the relationship between target occupancy and administrated dose of a given drug candidate,thus accelerating the development of effective PDE10A inhibitors.In this study,we designed and synthesized a novel ^(18)F-aryl PDE10A PET radioligand,codenamed[^(18)F]P10A-1910([^(18)F]9),in high radiochemical yield and molar activity via spirocyclic iodonium ylide-mediated radiofluorination.[^(18)F]9 possessed good in vitro binding affinity(IC_(50)=2.1 nmol/L)and selectivity towards PDE10A.Further,[^(18)F]9 exhibited reasonable lipophilicity(logD=3.50)and brain permeability(P_(app)>10×10^(−6) cm/s in MDCK-MDR1 cells).PET imaging studies of[^(18)F]9 revealed high striatal uptake and excellent in vivo specificity with reversible tracer kinetics.Preclinical studies in rodents revealed an improved plasma and brain stability of[^(18)F]9 when compared to the current reference standard for PDE10A-targeted PET,[^(18)F]MNI659.Further,dose–response experiments with a series of escalating doses of PDE10A inhibitor 1 in rhesus monkey brains confirmed the utility of[^(18)F]9 for evaluating target occupancy in vivo in higher species.In conclusion,our results indicated that[^(18)F]9 is a promising PDE10A PET radioligand for clinical translation.
基金Supported by the Climate Change Special Fund of the China Meteorological Administration(CCSF201919,CCSF201910,and CCSF202013)Natural Foundation Guidance Plan of Liaoning Province(2019-ZD-0859)National Key Research and Development Program of China(2017YFC1501801)。
文摘Based on the ground surface temperature(GST)and snow surface temperature(SST)measurements during the period of adjustment from manual to automatic observation systems in China,the influence of observation methods on GST and its relationship with snow cover is analyzed.GST is corrected by SST,and the correction effect is evaluated.The results show that,during the parallel observation period,the winter GSTs from automatic observations are generally higher than those from manual observations,with the automatically observed national daily GST 1.18°C higher.The adjustment has a greater impact on GSTs at 0200,0800,and 2000 Beijing Time(BT)than at 1400 BT,and it has the greatest impact in Northeast and Northwest China,with deviations of 5.24 and 2.09°C,respectively.The GST deviation is closely related to the snow depth and annual snow totals.The average daily GST deviation increases at the rate of 0.66°C per 1-cm increase of snow depth when it is<15 cm,while it tends to be stable at around 10°C for snow depth over 15 cm.The GST deviation at a station is affected by its winter snow totals in Northeast and Northwest China,where the largest deviations are found where snow totals are all above 1000 cm.After the correction with SST,the mean deviation between the automatic and manual observations as well as the false trend can be effectively reduced.Following the correction,the mean deviation of daily GST decreases by 5.8°C,and its trend decreases from 1.87 to 0.65°C decade-1.
基金supported financially by the NSFC(nos.51873050 and 21871069)the China Postdoctoral Science Foundation(no.2015M571401).
文摘Chemical systems that can replicate cellular behaviors are gaining increasing attention and are being used to study various biological processes.Here,a protein-or amylose-based assembly at an oil/water interface was employed to construct a large compartmentalized adipocyte-like structure,and a lipid droplet-like microcompartment(amylose-polymerstabilized 2-ethyl-1-hexanol microcompartment),which exhibits floating behaviors driven by the amylose-polymer micelle solubilization,was introduced inside these adipocyte-like structures.When the lipase-based catalytic reaction and the external oil composition were controlled and another lipid droplet-like microcompartment(lipase-stabilized tributyrin microcompartment)was introduced,then a series of dynamic behaviors were exhibited by the two types of lipid droplet-like microcompartments,including growth,self-sorting,and fusion within the adipocyte-like structures.Therefore,it is anticipated that this autonomous generation of hierarchical multicompartments represents a breakthrough compared to the traditional bottom-up strategies,and the artificial life systems we studied could contribute a chemical-based strategy of understanding the process of lipid droplet growth and fusion inside a living adipocyte cell.
