Diversity-oriented synthesis is a powerful and interesting synthetic tool for the rapid construction of structurally complex and privileged scaffolds from readily accessible starting materials.To date,diversity-orient...Diversity-oriented synthesis is a powerful and interesting synthetic tool for the rapid construction of structurally complex and privileged scaffolds from readily accessible starting materials.To date,diversity-oriented synthesis mostly relies on the employment of versatile reagents.Versatile reagents can be regulated as controllable and flexible building blocks for multipurpose utilizations.Over the past decade,a variety of multifunctional reagents have been developed.However,most versatile reagents usually need multi-step synthesis,thus restricting their wide application to a large extent.In terms of the practicalities and universalities,we prefer to pay more attention to the utilization of simple and practical versatile reagents with multiple reactivities,mainly including atropaldehyde acetals,aryl methyl ketones,vinylene carbonate,vinyl azides,aryldiazonium salts,rongalite,halodifluoromethyl compounds.Most importantly,these versatile reagents can also play different roles simultaneously in the same reaction,in which their different reactivities are converged into the final target products.Such strategy can not only offer more possibilities for the synthesis of several active pharmaceutical ingredients,but also minimize the occurrence of some side reactions by lessening the varieties of materials.Also,a perspective is given at the end of this review.展开更多
The Jiangmen Underground Neutrino Observatory(JUNO)is a large liquid scintillator detector designed to explore many topics in fundamental physics.In this study,the potential of searching for proton decay in the p→νK...The Jiangmen Underground Neutrino Observatory(JUNO)is a large liquid scintillator detector designed to explore many topics in fundamental physics.In this study,the potential of searching for proton decay in the p→νK^(+)mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification.Moreover,the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals.Based on these advantages,the detection efficiency for the proton decay via p→νK^(+)is 36.9%±4.9%with a background level of 0.2±0.05(syst)±0.2(stat)events after 10 years of data collection.The estimated sensitivity based on 200 kton-years of exposure is 9.6×1033 years,which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies.展开更多
Acid-catalyzed tandem reactions were established by employing a novel class of 2-arylglycerol derivative,5-aryl-1,3-dioxan-5-ol,as versatile 1,3-biselectrophile.In the reactions,5-aryl-1,3-dioxan-5-ol works like atrop...Acid-catalyzed tandem reactions were established by employing a novel class of 2-arylglycerol derivative,5-aryl-1,3-dioxan-5-ol,as versatile 1,3-biselectrophile.In the reactions,5-aryl-1,3-dioxan-5-ol works like atropaldehydes or 2-aryl malondialdehydes,and can react with 2-naphthols andβ-keto amides,allowing the synthesis of 4H-chromenes and 5-aryl-2-pyridinones.High yields,good functional group tolerance,broad substrate scope and simple reaction operation make this protocol attractive.展开更多
Nitrogen(N)is an important mineral element in apple production.Rapid estimation of apple tree N status is helpful for achieving precise N management.The objective of this work was to explore partial least squares(PLS)...Nitrogen(N)is an important mineral element in apple production.Rapid estimation of apple tree N status is helpful for achieving precise N management.The objective of this work was to explore partial least squares(PLS)regression in dimensional reduction of spectral data and build the diagnostic model.The spectral reflectance data were collected from Fuji apple trees with 4 levels of N fertilizer treatment in the Loess Plateau in 2018 and 2019 using an ASD portable spectroradiometer,and leaf total N content was obtained at the same time.The raw spectra were pretreated using Savitzky-Golay(SG)smoothing and a combination of SG and first-order derivative(SG_FD)or second-order derivative(SG_SD).The samples were divided into a calibration dataset and a prediction dataset using SPXY.Based on 4 factors of PLS regression,including latent variables(LVs),X-loading,variable importance in projection(VIP)and regression coefficients(RC),the 6 methods(LVs,X-loading,VIP_01,VIP_02,RC_01 and RC_02)were derived and used for variable extraction,based on which PLS model and ELM model were established.The results indicated that the spectral data processed by SG_FD had the highest signal-to-noise ratio and was selected for subsequent analysis.The amounts of variables extracted by LVs,X-loading,VIP_01,VIP_02,RC_01 and RC_02 were 6,11,18,305,26 and 88,respectively.The method of extracting variables with an RC threshold based on the minimum RMSEP(RC_02)could effectively avoid the omission of effective information.The RC_02 method was recommended for related research which required accurate wavelength information as a variable.The variable extraction method based on LVs generated an ELM model with a simple structure.The prediction results showed that the ELM model outperformed the PLS model.The PLS(LVs)_ELM model was the best;R2P,RMSEP and RPD were 0.837,2.393 and 2.220,respectively.展开更多
The Jiangmen Underground Neutrino Observatory(JUNO)features a 20 kt multi-purpose underground liquid scintillator sphere as its main detector.Some of JUNO's features make it an excellent location for^8B solar neut...The Jiangmen Underground Neutrino Observatory(JUNO)features a 20 kt multi-purpose underground liquid scintillator sphere as its main detector.Some of JUNO's features make it an excellent location for^8B solar neutrino measurements,such as its low-energy threshold,high energy resolution compared with water Cherenkov detectors,and much larger target mass compared with previous liquid scintillator detectors.In this paper,we present a comprehensive assessment of JUNO's potential for detecting^8B solar neutrinos via the neutrino-electron elastic scattering process.A reduced 2 MeV threshold for the recoil electron energy is found to be achievable,assuming that the intrinsic radioactive background^(238)U and^(232)Th in the liquid scintillator can be controlled to 10^(-17)g/g.With ten years of data acquisition,approximately 60,000 signal and 30,000 background events are expected.This large sample will enable an examination of the distortion of the recoil electron spectrum that is dominated by the neutrino flavor transformation in the dense solar matter,which will shed new light on the inconsistency between the measured electron spectra and the predictions of the standard three-flavor neutrino oscillation framework.IfDelta m^(2)_(21)=4.8times10^(-5);(7.5times10^(-5))eV^(2),JUNO can provide evidence of neutrino oscillation in the Earth at approximately the 3sigma(2sigma)level by measuring the non-zero signal rate variation with respect to the solar zenith angle.Moreover,JUNO can simultaneously measureDelta m^2_(21)using^8B solar neutrinos to a precision of 20% or better,depending on the central value,and to sub-percent precision using reactor antineutrinos.A comparison of these two measurements from the same detector will help understand the current mild inconsistency between the value of Delta m^2_(21)reported by solar neutrino experiments and the KamLAND experiment.展开更多
Solar,terrestrial,and supernova neutrino experiments are subject to muon-induced radioactive background.The China Jinping Underground Laboratory(CJPL),with its unique advantage of a 2400 m rock coverage and long dista...Solar,terrestrial,and supernova neutrino experiments are subject to muon-induced radioactive background.The China Jinping Underground Laboratory(CJPL),with its unique advantage of a 2400 m rock coverage and long distance from nuclear power plants,is ideal for MeV-scale neutrino experiments.Using a 1-ton prototype detector of the Jinping Neutrino Experiment(JNE),we detected 3 43 high-energy cosmic-ray muons and(7.86±3.97)muon-induced neutrons from an 820.28-day dataset at the first phase of CJPL(CJPL-I).Based on the muon-induced neutrons,we measured the corresponding muon-induced neutron yield in a liquid scintillator to be(3.44±1.86_(stat.)±0.76_(syst.))×10^(-4) μ^(-1)g^(-1)cm^(2) at an average muon energy of 340 GeV.We provided the first study for such neutron background at CJPL.A global fit including this measurement shows a power-law coefficient of(0.75±0.02) for the dependence of the neutron yield at the liquid scintillator on muon energy.展开更多
JUNO is a multi-purpose neutrino observatory under construction in the south of China.This publication presents new sensitivity estimates for the measurement of the △m_(31)^(2),△m_(21)^(2),sin^(2)θ_(12),and sin^(2)...JUNO is a multi-purpose neutrino observatory under construction in the south of China.This publication presents new sensitivity estimates for the measurement of the △m_(31)^(2),△m_(21)^(2),sin^(2)θ_(12),and sin^(2)θ_(13) oscillation parameters using reactor antineutrinos,which is one of the primary physics goals of the experiment.The sensitivities are obtained using the best knowledge available to date on the location and overburden of the experimental site,the nuclear reactors in the surrounding area and beyond,the detector response uncertainties,and the reactor antineutrino spectral shape constraints expected from the TAO satellite detector.It is found that the △m_(21)^(2) and sin^(2)θ_(12) oscillation parameters will be determined to 0.5%precision or better in six years of data collection.In the same period,the △m_(31)^(2) parameter will be determined to about 0.2%precision for each mass ordering hypothesis.The new precision represents approximately an order of magnitude improvement over existing constraints for these three parameters.展开更多
基金supported by the National Natural Science Foundation of China(U21A20497,62374033)Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(2021ZZ129)。
基金supported by the National Natural Science Foundation of China(No.22072049)National Key Research and Development Project(No.2022YFE0124100)+2 种基金Major Special Projects of Science and Technology of Ordos(No.2022EEDSKJZDZX003)Program for HUST Academic Frontier Youth Team(No.2019QYTD06)is also acknowledgedChen is also grateful for the financial support from China Scholarship Council(CSC).
文摘Diversity-oriented synthesis is a powerful and interesting synthetic tool for the rapid construction of structurally complex and privileged scaffolds from readily accessible starting materials.To date,diversity-oriented synthesis mostly relies on the employment of versatile reagents.Versatile reagents can be regulated as controllable and flexible building blocks for multipurpose utilizations.Over the past decade,a variety of multifunctional reagents have been developed.However,most versatile reagents usually need multi-step synthesis,thus restricting their wide application to a large extent.In terms of the practicalities and universalities,we prefer to pay more attention to the utilization of simple and practical versatile reagents with multiple reactivities,mainly including atropaldehyde acetals,aryl methyl ketones,vinylene carbonate,vinyl azides,aryldiazonium salts,rongalite,halodifluoromethyl compounds.Most importantly,these versatile reagents can also play different roles simultaneously in the same reaction,in which their different reactivities are converged into the final target products.Such strategy can not only offer more possibilities for the synthesis of several active pharmaceutical ingredients,but also minimize the occurrence of some side reactions by lessening the varieties of materials.Also,a perspective is given at the end of this review.
基金supported by the Chinese Academy of Sciencesthe National Key R&D Program of China+22 种基金the CAS Center for Excellence in Particle PhysicsWuyi Universitythe Tsung-Dao Lee Institute of Shanghai Jiao Tong University in Chinathe Institut National de Physique Nucléaire et de Physique de Particules (IN2P3) in Francethe Istituto Nazionale di Fisica Nucleare (INFN) in Italythe Italian-Chinese collaborative research program MAECI-NSFCthe Fond de la Recherche Scientifique (F.R.S-FNRS)FWO under the "Excellence of Science-EOS" in Belgiumthe Conselho Nacional de Desenvolvimento Científico e Tecnològico in Brazilthe Agencia Nacional de Investigacion y Desarrollo in Chilethe Charles University Research Centrethe Ministry of Education,Youth,and Sports in Czech Republicthe Deutsche Forschungsgemeinschaft (DFG)the Helmholtz Associationthe Cluster of Excellence PRISMA+ in Germanythe Joint Institute of Nuclear Research (JINR)Lomonosov Moscow State University in Russiathe joint Russian Science Foundation (RSF)National Natural Science Foundation of China (NSFC) research programthe MOST and MOE in Taiwan,Chinathe Chulalongkorn UniversitySuranaree University of Technology in Thailandthe University of California at Irvine in USA
文摘The Jiangmen Underground Neutrino Observatory(JUNO)is a large liquid scintillator detector designed to explore many topics in fundamental physics.In this study,the potential of searching for proton decay in the p→νK^(+)mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification.Moreover,the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals.Based on these advantages,the detection efficiency for the proton decay via p→νK^(+)is 36.9%±4.9%with a background level of 0.2±0.05(syst)±0.2(stat)events after 10 years of data collection.The estimated sensitivity based on 200 kton-years of exposure is 9.6×1033 years,which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies.
基金The National Key Research and Development Project(No.2022YFE0124100)Ordos Key Research and Development Project(No.2022EEDSKJZDZX003)+3 种基金National Natural Science Foundation of China(Nos.21872060,21902054,21761132014,and 22072049)the Open Research Fund(No.2022JYBKF01)of Key Laboratory of Material Chemistry for Energy Conversion and Storage(HUST),Ministry of Education,are acknowledged for the financial supportProgram for HUST Academic Frontier Youth Team(No.2019QYTD06)is also acknowledgedsupported by The Innovation and Talent Recruitment Base of New Energy Chemistry and Device。
文摘Acid-catalyzed tandem reactions were established by employing a novel class of 2-arylglycerol derivative,5-aryl-1,3-dioxan-5-ol,as versatile 1,3-biselectrophile.In the reactions,5-aryl-1,3-dioxan-5-ol works like atropaldehydes or 2-aryl malondialdehydes,and can react with 2-naphthols andβ-keto amides,allowing the synthesis of 4H-chromenes and 5-aryl-2-pyridinones.High yields,good functional group tolerance,broad substrate scope and simple reaction operation make this protocol attractive.
基金This work was supported by the National Key Research and Development Program of China(Grant No.2017YFD0201508).
文摘Nitrogen(N)is an important mineral element in apple production.Rapid estimation of apple tree N status is helpful for achieving precise N management.The objective of this work was to explore partial least squares(PLS)regression in dimensional reduction of spectral data and build the diagnostic model.The spectral reflectance data were collected from Fuji apple trees with 4 levels of N fertilizer treatment in the Loess Plateau in 2018 and 2019 using an ASD portable spectroradiometer,and leaf total N content was obtained at the same time.The raw spectra were pretreated using Savitzky-Golay(SG)smoothing and a combination of SG and first-order derivative(SG_FD)or second-order derivative(SG_SD).The samples were divided into a calibration dataset and a prediction dataset using SPXY.Based on 4 factors of PLS regression,including latent variables(LVs),X-loading,variable importance in projection(VIP)and regression coefficients(RC),the 6 methods(LVs,X-loading,VIP_01,VIP_02,RC_01 and RC_02)were derived and used for variable extraction,based on which PLS model and ELM model were established.The results indicated that the spectral data processed by SG_FD had the highest signal-to-noise ratio and was selected for subsequent analysis.The amounts of variables extracted by LVs,X-loading,VIP_01,VIP_02,RC_01 and RC_02 were 6,11,18,305,26 and 88,respectively.The method of extracting variables with an RC threshold based on the minimum RMSEP(RC_02)could effectively avoid the omission of effective information.The RC_02 method was recommended for related research which required accurate wavelength information as a variable.The variable extraction method based on LVs generated an ELM model with a simple structure.The prediction results showed that the ELM model outperformed the PLS model.The PLS(LVs)_ELM model was the best;R2P,RMSEP and RPD were 0.837,2.393 and 2.220,respectively.
基金This work was supported by the Chinese Academy of Sciences,the National Key R&D Program of China,the CAS Center for Excellence in Particle Physics,the Joint Large Scale Scientific Facility Funds of the NSFC and CAS,Wuyi University,and the Tsung-Dao Lee Instiute of Shanghai Jiao Tong University in China,the In stiut National de Physique Nucleaire et de Physique de Particules(IN2P3)in France,the Istituto Nazionale di Fisica Nucleare(INFN)in Italy,the Fond de la Recherche Scintifique(F.R.S-FNRS)and FWO under the"Excellence of Science-EOS"in Belgium,the Conselho Nacional de Desenvolvimento Cientificoce Tecnologico in Brazil,the Agencia Nacional de Investigacion y Desrrollo in Chile,the Charles University Research Centre and the Ministry of Education,Youth,and Sports in Czech Republic,the Deutsche Forschungsgemeinschaft(DFG),the Helmholtz Association,and the Cluster of Exellence PRISMA+in Germany,the Joint Institute of Nuclear Research(JINR),Lomonosov Moscow State University,and Russian Foundation for Basic Research(RFBR)in Russia,the MOST and MOE in Taiwan,the Chu-lalongkorm University and Suranaree University of Technology in Thailand,and the University of aliformia at Irvine in USA.
文摘The Jiangmen Underground Neutrino Observatory(JUNO)features a 20 kt multi-purpose underground liquid scintillator sphere as its main detector.Some of JUNO's features make it an excellent location for^8B solar neutrino measurements,such as its low-energy threshold,high energy resolution compared with water Cherenkov detectors,and much larger target mass compared with previous liquid scintillator detectors.In this paper,we present a comprehensive assessment of JUNO's potential for detecting^8B solar neutrinos via the neutrino-electron elastic scattering process.A reduced 2 MeV threshold for the recoil electron energy is found to be achievable,assuming that the intrinsic radioactive background^(238)U and^(232)Th in the liquid scintillator can be controlled to 10^(-17)g/g.With ten years of data acquisition,approximately 60,000 signal and 30,000 background events are expected.This large sample will enable an examination of the distortion of the recoil electron spectrum that is dominated by the neutrino flavor transformation in the dense solar matter,which will shed new light on the inconsistency between the measured electron spectra and the predictions of the standard three-flavor neutrino oscillation framework.IfDelta m^(2)_(21)=4.8times10^(-5);(7.5times10^(-5))eV^(2),JUNO can provide evidence of neutrino oscillation in the Earth at approximately the 3sigma(2sigma)level by measuring the non-zero signal rate variation with respect to the solar zenith angle.Moreover,JUNO can simultaneously measureDelta m^2_(21)using^8B solar neutrinos to a precision of 20% or better,depending on the central value,and to sub-percent precision using reactor antineutrinos.A comparison of these two measurements from the same detector will help understand the current mild inconsistency between the value of Delta m^2_(21)reported by solar neutrino experiments and the KamLAND experiment.
基金Supported in part by the National Natural Science Foundation of China (11620101004,11475093,12127808)the Key Laboratory of Particle&Radiation Imaging(Tsinghua University)+2 种基金the CAS Center for Excellence in Particle Physics (CCEPP)Guangdong Basic and Applied Basic Research Foundation(2019A1515012216)Portion of this work performed at Brookhaven National Laboratory is supported in part by the United States Department of Energy (DESC0012704)。
文摘Solar,terrestrial,and supernova neutrino experiments are subject to muon-induced radioactive background.The China Jinping Underground Laboratory(CJPL),with its unique advantage of a 2400 m rock coverage and long distance from nuclear power plants,is ideal for MeV-scale neutrino experiments.Using a 1-ton prototype detector of the Jinping Neutrino Experiment(JNE),we detected 3 43 high-energy cosmic-ray muons and(7.86±3.97)muon-induced neutrons from an 820.28-day dataset at the first phase of CJPL(CJPL-I).Based on the muon-induced neutrons,we measured the corresponding muon-induced neutron yield in a liquid scintillator to be(3.44±1.86_(stat.)±0.76_(syst.))×10^(-4) μ^(-1)g^(-1)cm^(2) at an average muon energy of 340 GeV.We provided the first study for such neutron background at CJPL.A global fit including this measurement shows a power-law coefficient of(0.75±0.02) for the dependence of the neutron yield at the liquid scintillator on muon energy.
基金Supported by the Chinese Academy of Sciencesthe National Key R&D Program of China+18 种基金the CAS Center for Excellence in Particle Physics,Wuyi Universitythe Tsung-Dao Lee Institute of Shanghai Jiao Tong University in Chinathe Institut National de Physique Nucléaire et de Physique de Particules(IN2P3)in Francethe Istituto Nazionale di Fisica Nucleare(INFN)in Italythe Italian-Chinese collaborative research program MAECI-NSFCthe Fond de la Recherche Scientifique(F.R.S-FNRS)FWO under the“Excellence of Science-EOS in Belgium”the Conselho Nacional de Desenvolvimento Científico e Tecnològico in Brazilthe Agencia Nacional de Investigacion y Desarrollo and ANID-Millennium Science Initiative Program-ICN2019_044 in Chilethe Charles University Research Centre and the Ministry of Education,Youth,and Sports in Czech Republicthe Deutsche Forschungsgemeinschaft(DFG)the Helmholtz Associationthe Cluster of Excellence PRISMA+in Germanythe Joint Institute of Nuclear Research(JINR)and Lomonosov Moscow State University in Russiathe joint Russian Science Foundation(RSF)National Natural Science Foundation of China(NSFC)research programthe MOST and MOE in Taiwanthe Chulalongkorn University and Suranaree University of Technology in Thailand,University of California at Irvinethe National Science Foundation in USA。
文摘JUNO is a multi-purpose neutrino observatory under construction in the south of China.This publication presents new sensitivity estimates for the measurement of the △m_(31)^(2),△m_(21)^(2),sin^(2)θ_(12),and sin^(2)θ_(13) oscillation parameters using reactor antineutrinos,which is one of the primary physics goals of the experiment.The sensitivities are obtained using the best knowledge available to date on the location and overburden of the experimental site,the nuclear reactors in the surrounding area and beyond,the detector response uncertainties,and the reactor antineutrino spectral shape constraints expected from the TAO satellite detector.It is found that the △m_(21)^(2) and sin^(2)θ_(12) oscillation parameters will be determined to 0.5%precision or better in six years of data collection.In the same period,the △m_(31)^(2) parameter will be determined to about 0.2%precision for each mass ordering hypothesis.The new precision represents approximately an order of magnitude improvement over existing constraints for these three parameters.