A method which adopts the combination of least squares support vector machine(LS-SVM) and Monte Carlo(MC) simulation is used to calculate the foundation settlement reliability.When using LS-SVM,choosing the traini...A method which adopts the combination of least squares support vector machine(LS-SVM) and Monte Carlo(MC) simulation is used to calculate the foundation settlement reliability.When using LS-SVM,choosing the training dataset and the values for LS-SVM parameters is the key.In a representative sense,the orthogonal experimental design with four factors and five levels is used to choose the inputs of the training dataset,and the outputs are calculated by using fast Lagrangian analysis continua(FLAC).The decimal ant colony algorithm(DACA) is also used to determine the parameters.Calculation results show that the values of the two parameters,and δ2 have great effect on the performance of LS-SVM.After the training of LS-SVM,the inputs are sampled according to the probabilistic distribution,and the outputs are predicted with the trained LS-SVM,thus the reliability analysis can be performed by the MC method.A program compiled by Matlab is employed to calculate its reliability.Results show that the method of combining LS-SVM and MC simulation is applicable to the reliability analysis of soft foundation settlement.展开更多
Synthetic chemistry plays an indispensable role in drug discovery,contributing to hit compounds identification,lead compounds optimization,candidate drugs preparation,and so on.As Nobel Prize laureate James Black emph...Synthetic chemistry plays an indispensable role in drug discovery,contributing to hit compounds identification,lead compounds optimization,candidate drugs preparation,and so on.As Nobel Prize laureate James Black emphasized,“the most fruitful basis for the discovery of a new drug is to start with an old drug”1.Late-stage modification or functionalization of drugs,natural products and bioactive compounds have garnered significant interest due to its ability to introduce diverse elements into bioactive compounds promptly.Such modifications alter the chemical space and physiochemical properties of these compounds,ultimately influencing their potency and druggability.To enrich a toolbox of chemical modification methods for drug discovery,this review focuses on the incorporation of halogen,oxygen,and nitrogen—the ubiquitous elements in pharmacophore components of the marketed drugs—through late-stage modification in recent two decades,and discusses the state and challenges faced in these fields.We also emphasize that increasing cooperation between chemists and pharmacists may be conducive to the rapid discovery of new activities of the functionalized molecules.Ultimately,we hope this review would serve as a valuable resource,facilitating the application of late-stage modification in the construction of novel molecules and inspiring innovative concepts for designing and building new drugs.展开更多
The chemical recycling of polyolefin presents a considerable challenge,especially as upcycling methods struggle with the reality that plastic wastes typically consist of mixtures of polyethylene(PE),polystyrene(PS),an...The chemical recycling of polyolefin presents a considerable challenge,especially as upcycling methods struggle with the reality that plastic wastes typically consist of mixtures of polyethylene(PE),polystyrene(PS),and polypropylene(PP).We report a catalytic aerobic oxidative approach for polyolefins upcycling with the corresponding carboxylic acids as the product.This method encompasses three key innovations.First,it operates under atmospheric pressure and mild conditions,using O_(2) or air as the oxidant.Second,it is compatible with high-density polyethylene,low-density polyethylene,PS,PP,and their blends.Third,it uses an economical and recoverable metal catalyst.It has been demonstrated that this approach can efficiently degrade mixed wastes of plastic bags,bottles,masks,and foam boxes.展开更多
Over the past 40 years,PM2.5 pollution in North China has become increasingly serious and progressively exposes the densely populated areas to pollutants.However,due to limited ground data,it is challenging to estimat...Over the past 40 years,PM2.5 pollution in North China has become increasingly serious and progressively exposes the densely populated areas to pollutants.However,due to limited ground data,it is challenging to estimate accurate PM2.5 exposure levels,further making it unfavorable for the prediction and prevention of PM2.5 pollutions.This paper therefore uses the mixed effect model to estimate daily PM2.5 concentrations of North China between 2003 and 2015 with ground observation data and MODIS AOD satellite data.The tempo-spatial characteristics of PM2.s and the influence of meteorological elements on PM25 is discussed with EOF and canonical correlation analysis respectively.Results show that overall R2 is 0.36 and the root mean squared predicted error was 30.1μg/m^3 for the model prediction.Our time series analysis showed that,the Taihang Mountains acted as a boundary between the high and low pollution areas in North China;while the northern part of Henan Province,the southern part of Hebei Province and the western part of Shandong Province were the most polluted areas.Although,in 2004,2009 and dates after 2013,PM25 concentrations were relatively low.Meteorological/topography conditions,that include high surface humidity of area in the range of 34°-40°N and 119°-124°E,relatively low boundary layer heights,and southerly and easterly winds from the east and north area were common factors attributed to haze in the most polluted area.Overall,the spatial distribution of increasingly concentrated PM2.5 pollution in North China are consistent with the local emission level,unfavorable meteorological conditions and topographic changes.展开更多
The increasing number of gas-fired units has significantly intensified the coupling between electric and gas power networks.Traditionally,nonlinearity and nonconvexity in gas flow equations,together with renewable-ind...The increasing number of gas-fired units has significantly intensified the coupling between electric and gas power networks.Traditionally,nonlinearity and nonconvexity in gas flow equations,together with renewable-induced stochasticity,resulted in a computationally expensive model for unit commitment in electricity-gas coupled integrated energy systems(IES).To accelerate stochastic day-ahead scheduling,we applied and modified Progressive Hedging(PH),a heuristic approach that can be computed in parallel to yield scenario-independent unit commitment.Through early termination and enumeration techniques,the modified PH algorithm saves considerable com,putational time for certain generation cost settings or when the scale of the IES is large.Moreover,an adapted second-order cone relaxation(SOCR)is utilized to tackle the nonconvex gas flow equation.Case studies were performed on the IEEE 24.bus system/Belgium 20-node gas system and the IEEE 118-bus system/Belgium 20-node gas system.The computational efficiency when employing PH is 188 times that of commercial software,and the algorithm even outperforms Benders Decomposition.At the same time,the gap between the PH algorithm and the benchmark is less than 0.01% in both IES systems,which proves that the solutions produced by PH reach acceptable optimality in this stochastic UC problem.展开更多
Foxj1 has been found to play an important role in cilia formation and function in vertebrates. The zebrafish or Xenopus genome expresses two Foxjl genes, foxjlalFoxJ1 and foxjlb/FoxJ1.2. In this study, we have generat...Foxj1 has been found to play an important role in cilia formation and function in vertebrates. The zebrafish or Xenopus genome expresses two Foxjl genes, foxjlalFoxJ1 and foxjlb/FoxJ1.2. In this study, we have generated a zebrafish transgenic line T2BGSZIO by Tol2 transposon-based gene trapping approach. T2BGSZ10 transgenic fish carry an insertion of the transposon genome into the first intron of thefoxj1b locus. This insertion results in GFP expression in the forebrain, otic vesicles, floorplate, pronephric ducts and other domains during embryogenesis, which recaptures the expression pattern offoxj1b. Although normal expression offoxj1b is dramatically reduced, T2BGSZ10 homozygous embryos develop normally and grow to adulthood without detectable defects, which may be due to the incomplete interruption of foxjlb expression. Nevertheless, this transgenic line may serve as a useful model for dynamic observation of GFP-labeled tissues and organs and for isolation of GFP-labeled cells.展开更多
The electrophilic fluorination of unsaturated compounds provides a reliable approach to the generation of organofluorides,which are used widely in agrochemicals,pharmaceuticals,and other materials.Numerous active elec...The electrophilic fluorination of unsaturated compounds provides a reliable approach to the generation of organofluorides,which are used widely in agrochemicals,pharmaceuticals,and other materials.Numerous active electrophilic fluorine reagents,such as the fluorine molecule(F_(2))or xenon difluoride(XeF_(2)),have been applied in fluorination.However,these reagents suffer from their hazardous,toxic,corrosive,and poor selective properties,and the relatively weak electrophilicity of Selectfluor or N-fluorobenzenesulfonimide(NFSI)usually limits their broad applications.Herein,we disclose nitromethane(MeNO_(2))as an efficient activator of Selectfluor and NFSI,as well as a stabilizer of carbocations.Therefore,the fluoro-azidation,fluoroamination,fluoroesterification of styrenes,and C–H fluorination of(hetero)arenes were well realized just by the facilitation of MeNO_(2).The mild reaction conditions and practicability made our current method a versatile protocol for accessing organofluorides.展开更多
文摘A method which adopts the combination of least squares support vector machine(LS-SVM) and Monte Carlo(MC) simulation is used to calculate the foundation settlement reliability.When using LS-SVM,choosing the training dataset and the values for LS-SVM parameters is the key.In a representative sense,the orthogonal experimental design with four factors and five levels is used to choose the inputs of the training dataset,and the outputs are calculated by using fast Lagrangian analysis continua(FLAC).The decimal ant colony algorithm(DACA) is also used to determine the parameters.Calculation results show that the values of the two parameters,and δ2 have great effect on the performance of LS-SVM.After the training of LS-SVM,the inputs are sampled according to the probabilistic distribution,and the outputs are predicted with the trained LS-SVM,thus the reliability analysis can be performed by the MC method.A program compiled by Matlab is employed to calculate its reliability.Results show that the method of combining LS-SVM and MC simulation is applicable to the reliability analysis of soft foundation settlement.
基金Financial support from the National Key R&D Program of China(No.2021YFA1501700)the National Natural Science Foundation of China(Nos.22293014,22131002,22161142019,81821004)+1 种基金the Ministry of Science and Technology of China Changping Laboratory,Peking University Special Fund for COVID-19the New Cornerstone Science Foundation through the XPLORER PRIZE。
文摘Synthetic chemistry plays an indispensable role in drug discovery,contributing to hit compounds identification,lead compounds optimization,candidate drugs preparation,and so on.As Nobel Prize laureate James Black emphasized,“the most fruitful basis for the discovery of a new drug is to start with an old drug”1.Late-stage modification or functionalization of drugs,natural products and bioactive compounds have garnered significant interest due to its ability to introduce diverse elements into bioactive compounds promptly.Such modifications alter the chemical space and physiochemical properties of these compounds,ultimately influencing their potency and druggability.To enrich a toolbox of chemical modification methods for drug discovery,this review focuses on the incorporation of halogen,oxygen,and nitrogen—the ubiquitous elements in pharmacophore components of the marketed drugs—through late-stage modification in recent two decades,and discusses the state and challenges faced in these fields.We also emphasize that increasing cooperation between chemists and pharmacists may be conducive to the rapid discovery of new activities of the functionalized molecules.Ultimately,we hope this review would serve as a valuable resource,facilitating the application of late-stage modification in the construction of novel molecules and inspiring innovative concepts for designing and building new drugs.
基金We acknowledge the NSFC(Nos.22293014,22131002,22161142019)the National Key R&D Program of China(No.2021YFA1501700)+2 种基金the New Cornerstone Science Foundation through the XPLORER PRIZE for financial support.We would also like to thank our colleagues Prof.Jian Pei,Prof.Rong Zhu,and Prof.Aiwen Lei for sharing their instruments and helpful suggestionsDr.Zhenjin Liang and Ms.Qinqin Wei for their helpful discussionsand Mr.Zhenpeng Wang for his help in the analytical testing.
文摘The chemical recycling of polyolefin presents a considerable challenge,especially as upcycling methods struggle with the reality that plastic wastes typically consist of mixtures of polyethylene(PE),polystyrene(PS),and polypropylene(PP).We report a catalytic aerobic oxidative approach for polyolefins upcycling with the corresponding carboxylic acids as the product.This method encompasses three key innovations.First,it operates under atmospheric pressure and mild conditions,using O_(2) or air as the oxidant.Second,it is compatible with high-density polyethylene,low-density polyethylene,PS,PP,and their blends.Third,it uses an economical and recoverable metal catalyst.It has been demonstrated that this approach can efficiently degrade mixed wastes of plastic bags,bottles,masks,and foam boxes.
基金the National Key Technology R&D Program(Grant No.2018YFA0606104)the National Natural Science Foundation of China(Grant No.41471073).
文摘Over the past 40 years,PM2.5 pollution in North China has become increasingly serious and progressively exposes the densely populated areas to pollutants.However,due to limited ground data,it is challenging to estimate accurate PM2.5 exposure levels,further making it unfavorable for the prediction and prevention of PM2.5 pollutions.This paper therefore uses the mixed effect model to estimate daily PM2.5 concentrations of North China between 2003 and 2015 with ground observation data and MODIS AOD satellite data.The tempo-spatial characteristics of PM2.s and the influence of meteorological elements on PM25 is discussed with EOF and canonical correlation analysis respectively.Results show that overall R2 is 0.36 and the root mean squared predicted error was 30.1μg/m^3 for the model prediction.Our time series analysis showed that,the Taihang Mountains acted as a boundary between the high and low pollution areas in North China;while the northern part of Henan Province,the southern part of Hebei Province and the western part of Shandong Province were the most polluted areas.Although,in 2004,2009 and dates after 2013,PM25 concentrations were relatively low.Meteorological/topography conditions,that include high surface humidity of area in the range of 34°-40°N and 119°-124°E,relatively low boundary layer heights,and southerly and easterly winds from the east and north area were common factors attributed to haze in the most polluted area.Overall,the spatial distribution of increasingly concentrated PM2.5 pollution in North China are consistent with the local emission level,unfavorable meteorological conditions and topographic changes.
基金supported by the National Key Research and Development Program(SQ 2020YFE0200400)the National Natural Science Foundation of China(No.52007123)the Science,Technology and Innovation Commission of Shenzhen Municipality(No.JCYJ 20170411152331932).
文摘The increasing number of gas-fired units has significantly intensified the coupling between electric and gas power networks.Traditionally,nonlinearity and nonconvexity in gas flow equations,together with renewable-induced stochasticity,resulted in a computationally expensive model for unit commitment in electricity-gas coupled integrated energy systems(IES).To accelerate stochastic day-ahead scheduling,we applied and modified Progressive Hedging(PH),a heuristic approach that can be computed in parallel to yield scenario-independent unit commitment.Through early termination and enumeration techniques,the modified PH algorithm saves considerable com,putational time for certain generation cost settings or when the scale of the IES is large.Moreover,an adapted second-order cone relaxation(SOCR)is utilized to tackle the nonconvex gas flow equation.Case studies were performed on the IEEE 24.bus system/Belgium 20-node gas system and the IEEE 118-bus system/Belgium 20-node gas system.The computational efficiency when employing PH is 188 times that of commercial software,and the algorithm even outperforms Benders Decomposition.At the same time,the gap between the PH algorithm and the benchmark is less than 0.01% in both IES systems,which proves that the solutions produced by PH reach acceptable optimality in this stochastic UC problem.
基金supported by the National High-tech R&D Program (863 Program) (No. 2006AA02Z167)the Major Science Programs of China (No. 2006CB943401)the National Basic Research Program of China (No. 2005CB522502)
文摘Foxj1 has been found to play an important role in cilia formation and function in vertebrates. The zebrafish or Xenopus genome expresses two Foxjl genes, foxjlalFoxJ1 and foxjlb/FoxJ1.2. In this study, we have generated a zebrafish transgenic line T2BGSZIO by Tol2 transposon-based gene trapping approach. T2BGSZ10 transgenic fish carry an insertion of the transposon genome into the first intron of thefoxj1b locus. This insertion results in GFP expression in the forebrain, otic vesicles, floorplate, pronephric ducts and other domains during embryogenesis, which recaptures the expression pattern offoxj1b. Although normal expression offoxj1b is dramatically reduced, T2BGSZ10 homozygous embryos develop normally and grow to adulthood without detectable defects, which may be due to the incomplete interruption of foxjlb expression. Nevertheless, this transgenic line may serve as a useful model for dynamic observation of GFP-labeled tissues and organs and for isolation of GFP-labeled cells.
基金the National Natural Science Foundation of China(nos.21871011,21602005,21632001,and 21772002)the Drug Innovation Major Project(2018ZX09711-001)the Open Fund of State Key Laboratory of Pharmaceutical Biotechnology,Nanjing University,China(grant no.KF-GN-201906).
文摘The electrophilic fluorination of unsaturated compounds provides a reliable approach to the generation of organofluorides,which are used widely in agrochemicals,pharmaceuticals,and other materials.Numerous active electrophilic fluorine reagents,such as the fluorine molecule(F_(2))or xenon difluoride(XeF_(2)),have been applied in fluorination.However,these reagents suffer from their hazardous,toxic,corrosive,and poor selective properties,and the relatively weak electrophilicity of Selectfluor or N-fluorobenzenesulfonimide(NFSI)usually limits their broad applications.Herein,we disclose nitromethane(MeNO_(2))as an efficient activator of Selectfluor and NFSI,as well as a stabilizer of carbocations.Therefore,the fluoro-azidation,fluoroamination,fluoroesterification of styrenes,and C–H fluorination of(hetero)arenes were well realized just by the facilitation of MeNO_(2).The mild reaction conditions and practicability made our current method a versatile protocol for accessing organofluorides.