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Exploring Boundary Layer Physics and Atmospheric Chemistry in Megacities:Insights from the Beijing 325 m Meteorological Tower
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作者 Yele SUN Zifa WANG +8 位作者 Linlin WANG Xueling CHENG Weiqi XU Yu SHI Wei ZHOU Yan LI Fei HU Zhiqiu GAO Zhongxiang HONG 《Advances in Atmospheric Sciences》 2025年第4期713-730,共18页
The Beijing 325 m meteorological tower stands as a pivotal research platform for exploring atmospheric boundary layer physics and atmospheric chemistry.With a legacy spanning 45 years,the tower has played a crucial ro... The Beijing 325 m meteorological tower stands as a pivotal research platform for exploring atmospheric boundary layer physics and atmospheric chemistry.With a legacy spanning 45 years,the tower has played a crucial role in unraveling the complexities of urban air pollution,atmospheric processes,and climate change in Beijing,China.This review paper provides a comprehensive overview of the measurements on the tower over the past two decades.Through long-term comprehensive observations,researchers have elucidated the intricate relationships between anthropogenic emissions,meteorological dynamics,and atmospheric composition,shedding light on the drivers of air pollution and its impacts on public health.The vertical measurements on the tower also enable detailed investigations into boundary layer dynamics,turbulent mixing,and pollutant dispersion,providing invaluable data for validating chemical transport models.Key findings from the tower’s research include the identification of positive feedback mechanisms between aerosols and the boundary layer,the characterization of pollutant sources and transport pathways,the determination of fluxes of gaseous and particulate species,and the assessment of the effectiveness of pollution control measures.Additionally,isotopic measurements have provided new insights into the sources and formation processes of particulate matter and reactive nitrogen species.Finally,the paper outlines future directions for tower-based research,emphasizing the need for long-term comprehensive measurements,the development of innovative tower platforms,and integration of emerging technologies. 展开更多
关键词 meteorological tower boundary layer physics aerosol composition vertical distributions formation mechanisms aerosol-boundary interactions
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Benchmarking model chemistry composite calculations for vertical ionization potential of molecular systems
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作者 Bingwei Wang Yihong Ding Xiao Tian 《Chinese Chemical Letters》 2025年第2期508-511,共4页
In chemical science,the vertical ionization potential(VIP)is a crucial metric for understanding the electronegativity,hardness and softness of chemical material systems as well as the electronic structure and stabilit... In chemical science,the vertical ionization potential(VIP)is a crucial metric for understanding the electronegativity,hardness and softness of chemical material systems as well as the electronic structure and stability of molecules.Ever since the last century,the model chemistry composite methods have witnessed tremendous developments in computing the thermodynamic properties as well as the barrier heights.However,their performance in realm of the vertical electron processes of molecular systems has been rarely explored.In this study,we for the first time benchmarked the model chemistry composite methods(e.g.,CBS-QB3,G4 and W1BD)in comparison with the commonly used Koopmans's theorem(KT),electron propagator theory(e.g.,OVGF,D2,P3 and P3+)and CCSD(T)methods in calculating the VIP for up to 613 molecular systems with available experimental measurements.The large-scale test calculations strongly showed that the CBS-QB3 model chemistry composite technique can be well recommended to calculate VIP from the perspectives of accuracy,economy and applicability.Notably,the VIP values of up to 7 molecules were identified to have the absolute errors of larger than 0.3 e V at all calculation levels,which have strong hints that their VIP experimental values should be re-investigated. 展开更多
关键词 Model chemistry Vertical ionization potential Composite methods Molecular systems CBS-QB3
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Bioinspired polydopamine interface reinforced boron-Viton composites with high structure stability and energy releasing efficiency
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作者 Liu Yang Liu Yuezhou +2 位作者 Gao Fulei Liu Yingzhe Wang Yinglei 《Defence Technology(防务技术)》 2026年第1期330-339,共10页
Boron has attracted increasing attention in the field of high-energy explosives and propellants due to its high volume calorific value and mass calorific value.However,the complicated combustion process and low combus... Boron has attracted increasing attention in the field of high-energy explosives and propellants due to its high volume calorific value and mass calorific value.However,the complicated combustion process and low combustion efficiency hinder its wide application.To tackle this challenge,bioinspired polydopamine(PDA)interface reinforced boron-Viton composites,with high structure stability and excellent energy releasing efficiency,are designed and prepared,combining the interface regulation of PDA biomimetic materials and combustion promotion of fluoropolymers.Firstly,the stronger adsorption energy of PDA with boron compared to Viton is demonstrated by molecular dynamics simulations.Next,B@PDA@Viton is prepared by the combination of in-situ dopamine polymerization and solvent/nonsolvent method,and the double-layer core-shell structure is confirmed by XPS,FTIR,and TEM characterizations.TG-DSC analysis shows that B@PDA@Viton possesses superior thermal properties,with a 55.48%increase in oxidation heat compared to raw B.Furthermore,ignition and combustion performance tests indicate that B@PDA@Viton reduces ignition delay by 57.56%and increases heat of combustion by 68.63%relative to raw B.These findings elucidate the ignition and combustion mechanisms of B@PDA@Viton.This work not only developed high-performance boron-based composite fuels but also provided insights into the development of boron-based fuels. 展开更多
关键词 Boron powder POLYDOPAMINE Ignition and combustion PROPELLANT Energetic materials
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A high-energy powder with excellent combustion reaction performance:Surface modification strategy of boron powder based on non-thermal plasma
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作者 Kangkang Li Jianyong Xu +9 位作者 Xiaoting Lei Mengzhe Yang Jing Liu Luqi Guo Pengfei Cui Dihua Ouyang Chunpei Yu He Cheng Jiahai Ye Wenchao Zhang 《Defence Technology(防务技术)》 2026年第1期289-300,共12页
The presence of a surface oxide film(B_(2)O_(3))on boron(B)particles significantly compromises their combustion efficiency and kinetic performance in fuel-rich solid propellants.This study proposes an innovative conti... The presence of a surface oxide film(B_(2)O_(3))on boron(B)particles significantly compromises their combustion efficiency and kinetic performance in fuel-rich solid propellants.This study proposes an innovative continuous modification strategy combining non-thermal plasma(NTP)etching with fluorocarbon passivation.Characterization and kinetic analysis revealed that reactive plasma species—including atomic hydrogen(H),electronically excited molecular hydrogen(H_(2)^(*)),vibrationally excited molecular hydrogen(H_(2)v),and hydrogen ions(H^(+))—dominate the reduction of B_(2)O_(3)through lowering the transition energy barrier and shifting the reaction spontaneity.Subsequent argon plasma fragmentation of C_(8)F_(18)generates fluorocarbon radicals that form conformal passivation coatings(thickness:7 nm)on purified boron surfaces.The modified boron particles exhibit 37.5℃lower exothermic peak temperature and 27.2%higher heat release(14.8 kJ/g vs.11.6 kJ/g)compared to untreated counterparts.Combustion diagnostics reveal 194%increase in maximum flame height(135.10 mm vs.46.03 mm)and 134%enhancement in flame propagation rate(4.44 cm/s vs.1.90 cm/s).This NTP-based surface engineering approach establishes a scalable pathway for developing highperformance boron-based energetic composites. 展开更多
关键词 Oxide film materials Surface modification Boron powder Non-thermal plasma Combustion performance
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Detonation characteristics of the solid-liquid mixed fuel cloud of Al/B/MgH_(2)/DEE/IPN
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作者 Zhangjun Wu Xianzhao Song +4 位作者 Shuxin Deng Bingbing Yu Yongxu Wang Rhoda Afriyie Mensah Suning Mei 《Defence Technology(防务技术)》 2026年第1期377-388,共12页
To elucidate the dispersion and explosion characteristics of multi-metal powder and liquid composite fuel formulations,high-energy metal powders(aluminum(Al),boron(B),and magnesium hydride(MgH_(2)))are incorporated in... To elucidate the dispersion and explosion characteristics of multi-metal powder and liquid composite fuel formulations,high-energy metal powders(aluminum(Al),boron(B),and magnesium hydride(MgH_(2)))are incorporated into a liquid fuel primarily composed of diethyl ether(DEE)and isopropyl nitrate(IPN).The explosion characteristics of different solid-liquid fuel-air-explosive(FAE)under unconfined conditions are investigated using a high-speed camera,infrared thermal imaging,and a pressure measurement system.Results demonstrate that high-energy metal powders significantly enhance detonation energy dissipation,with aluminum exhibiting the most pronounced effect.Fuel 5#(45.4 wt%DEE,9.2 wt%IPN,29.5 wt%Al,9.1 wt%B,6.8 wt%MgH_(2))exhibits superior explosion performance,achieving higher values of overpressure,impulse,and thermal radiation damage during the detonation stage compared to other fuels.However,Fuel 5#also displays faster decay rates,attributed to accelerated heat release rates induced by B and MgH_(2)powders.This study reveals that different metal powders in solid-liquid FAE exhibit distinct enhancements in explosion performance,providing critical insights for optimizing composite fuel design. 展开更多
关键词 Detonable aerosol OVERPRESSURE Shock wave Deflagration to detonation transition Temperature field
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Seed-mediated solid-phase synthesis of carbon-confined Ni_(3)Ga_(1) intermetallic nanocubes for highly selective hydrogenation
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作者 Yifan Liu Shiqiang Liu +4 位作者 Xiaoxue Wang Shingo Hasegawa Ken Motokura Guangying Fu Yong Yang 《Nano Research》 2026年第1期324-335,共12页
Atomically ordered precious intermetallic nanoparticles have garnered significant attention for diverse applications due to their well-defined surface atomic arrangements and exceptional electronic and geometric prope... Atomically ordered precious intermetallic nanoparticles have garnered significant attention for diverse applications due to their well-defined surface atomic arrangements and exceptional electronic and geometric properties.However,synthesizing non-precious ordered intermetallics that exhibit high stability under operating conditions remains a formidable challenge,primarily owing to their strong oxyphilicity,highly negative reduction potentials,and low corrosion resistance.In this work,we report a facile yet versatile seed-mediated solid-phase approach for fabricating uniform Ni_(3)Ga_(1) intermetallic nanocubes(NCs)fully encapsulated within N-doped carbon layers(denoted as Ni_(3)Ga_(1)@NC-800).Extensive characterization confirms the formation of a unique core-shell architecture,with atomic-resolution structural analysis and X-ray absorption fine structure measurements unequivocally verifying the atomically ordered Ni_(3)Ga_(1) intermetallic phase.The Ni_(3)Ga_(1)@NC-800 catalyst demonstrates exceptional performance in the 1,4-hydrogenation of α,β-unsaturated carbonyl compounds,exhibiting both remarkable activity and exclusive selectivity while maintaining high stability over multiple reaction cycles without observable performance decay.Combined experimental and theoretical calculations reveal that the strong interatomic p-d orbital hybridization facilitates electron transfer from Ga to Ni atoms,resulting in electron localization on ordered Ni atoms.This electronic configuration positively influences H_(2)activation and optimizes substrate adsorption strength,thereby substantially improving catalytic efficiency.Furthermore,this synthetic strategy proves generalizable,successfully extending to the synthesis of other non-precious ordered Ni_(1)Sn_(1) and Ni_(2)In_(3) intermetallics confined within N-doped carbon matrices. 展开更多
关键词 non-precious intermetallics Ni_(3)Ga_(1) solid-phase synthesis selective hydrogenation confined catalyst
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Investigation of natural and anthropogenic effects on aerosols optical properties over the Western Pacific ocean by the research vessel KEXUE
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作者 Jinyuan Xin Yining Ma +6 位作者 Xiangguang Zhang Yongjing Ma Xiaoyan Wu Fangkun Wu Quan Liu Yilong Lyu Jiawei Jiang 《Journal of Environmental Sciences》 2026年第1期596-605,共10页
In winter 2018,an aerosol physicochemical experiment was conducted in the Western Pacific Ocean(WPO)aboard the Research Vessel KEXUE of Chinese Academy of Sciences.This study systematically investigated both natural a... In winter 2018,an aerosol physicochemical experiment was conducted in the Western Pacific Ocean(WPO)aboard the Research Vessel KEXUE of Chinese Academy of Sciences.This study systematically investigated both natural and anthropogenic effects on marine aerosols optical properties,as well as the applicability of multi-satellite products and IMPROVE equation.The averaged aerosol optical depth(AOD500 nm)was 0.31±0.16 andÅngström exponent440–675 nm was 0.29±0.30.In offshore China,significant anthropogenic emissions affected the marine environment.In remote WPO,dust aerosols transported from northern China,Siberia,Central Asia,and those settling from the upper troposphere originating from north Africa,Arabian peninsula,and western India,were dominant.The spatial trends of AOD were opposite in the mid-latitude and southern seas of WPO.The highest AOD,0.32±0.23,appeared along the coast of South Asia at mid-latitude,decreasing from offshore seas to remote oceans.In low-latitude and equatorial seas,AOD significantly increased from coast to remote oceans.Ångström exponent dropped significantly from the coast to remote oceans as anthropogenic influence diminished across the entire WPO.Correlation analysis showed that both MODIS-C6 and Himawari AOD prod-ucts showed similar applicability in coastal urban areas,while Himawari AOD is highly recommended for coastal background and marine environment due to its finer resolution.The extinction coefficient derived from PM_(2.5) chemical compositions using IMPROVE algorithm exhibited a significant correlation(R^(2)=0.58)with the con-currently measured AOD in the absence of long-distance transport,suggesting that the IMPROVE is a reasonable proxy of the columnar average of marine aerosol extinctions free from transport influences. 展开更多
关键词 Aerosol optical properties Natural and anthropogenic effects Improve algorithm Ship-borne experiment Western Pacific Ocean
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Chemistry under extreme conditions: Pressure evolution of chemical bonding and structure in dense solids 被引量:9
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作者 Choong-Shik Yoo 《Matter and Radiation at Extremes》 SCIE CAS 2020年第1期59-72,共14页
Recent advances in high-pressure technologies and large-scale experimental and computational facilities have enabled scientists,at an unprecedented rate,to discover and predict novel states and materials under the ext... Recent advances in high-pressure technologies and large-scale experimental and computational facilities have enabled scientists,at an unprecedented rate,to discover and predict novel states and materials under the extreme pressure-temperature conditions found in deep,giant-planet interiors.Based on a well-documented body of work in this field of high-pressure research,we elucidate the fundamental principles that govern the chemistry of dense solids under extreme conditions.These include:(i)the pressure-induced evolution of chemical bonding and structure of molecular solids to extended covalent solids,ionic solids and,ultimately,metallic solids,as pressure increases to the terapascal regime;(ii)novel properties and complex transition mechanisms,arising from the subtle balance between electron hybridization(bonding)and electrostatic interaction(packing)in densely packed solids;and(iii)new dense framework solids with high energy densities,and with tunable properties and stabilities under ambient conditions.Examples are taken primarily fromlow-Z molecular systems that have scientific implications for giant-planet models,condensed materials physics,and solid-state core-electron chemistry. 展开更多
关键词 SOLIDS BONDING EXTREME
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A Global Ocean Biogeochemistry General Circulation Model and its Simulations 被引量:4
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作者 徐永福 李阳春 储敏 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2013年第3期922-939,共18页
An ocean biogeochemistry model was developed and incorporated into a global ocean general circulation model (LICOM) to form an ocean biogeochemistry general circulation model (OBGCM). The model was used to study t... An ocean biogeochemistry model was developed and incorporated into a global ocean general circulation model (LICOM) to form an ocean biogeochemistry general circulation model (OBGCM). The model was used to study the natural carbon cycle and the uptake and storage of anthropogenic CO2 in the ocean. A global export production of 12.5 Pg C yr-1 was obtained. The model estimated that in the pre-industrial era the global equatorial region within ~15~ of the equator released 0.97 Pg C yr-1 to the atmosphere, which was balanced by the gain of CO2 in other regions. The post-industrial air sea CO2 flux indicated the oceanic uptake of CO2 emitted by human activities. An increase of 20-50 ~mol kg-1 for surface dissolved inorganic carbon (DIC) concentrations in the 1990s relative to pre-industrial times was obtained in the simulation, which was consistent with data-based estimates. The model generated a total anthropogenic carbon inventory of 105 Pg C as of 1994, which was within the range of estimates by other researchers. Various transports of both natural and anthropogenic DIC as well as labile dissolved organic carbon (LDOC) were estimated from the simulation. It was realized that the Southern Ocean and the high-latitude region of the North Pacific are important export regions where accumulative air-sea CO2 fluxes are larger than the DIC inventory, whereas the subtropical regions are acceptance regions. The interhemispheric transport of total natural carbon (DIC+LDOC) was found to be northward (0.11 Pg C yr-1), which was just balanced by the gain of carbon from the atmosphere in the Southern Hemisphere. 展开更多
关键词 ocean biogeochemistry model natural carbon anthropogenic carbon meridional transport
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Precipitation Chemistry and Corresponding Transport Patterns of Influencing Air Masses at Huangshan Mountain in East China 被引量:9
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作者 SHI ChunE DENG Xueliang +2 位作者 YANG Yuanjian HUANG Xiangrong WU Biwen 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2014年第5期1157-1166,共10页
One hundred and ten samples of rainwater were collected for chemical analysis at the summit of Huangshan Mountain, a high-altitude site in East China, from July 2010 to June 2011. The volume-weighted-mean (VWM) pH f... One hundred and ten samples of rainwater were collected for chemical analysis at the summit of Huangshan Mountain, a high-altitude site in East China, from July 2010 to June 2011. The volume-weighted-mean (VWM) pH for the whole sampling period was 5.03. SO2- and Ca2+ were the most abundant anion and cation, respectively. The ionic concentrations varied monthly with the highest concentrations in winter/spring and the lowest in summer. Evident inter-correlations were found among most ions, indicating the common sources for some species and fully mixing characteristics of the alpine precipitation chemistry. The VWM ratio of [SO]-]/[NO3] was 2.54, suggesting the acidity of rainwater comes from both nitric and sulfuric acids. Compared with contemporary observations at other alpine continental sites in China, the precipitation at Huangshan Mountain was the least polluted, with the lowest ionic concentrations. Trajectories to Huangshan Mountain on rainy days could be classified into six groups. The rainwater with influencing air masses originating in Mongolia was the most polluted with limited effect. The emissions of Jiangxi, Anhui, Zhejiang and Jiangsu provinces had a strong influence on the overall rain chemistry at Huangshan Mountain. The rainwater with influencing air masses from Inner Mongolia was heavily polluted by anthropogenic pollutants. 展开更多
关键词 precipitation chemistry air mass inter-relationship transport pattern Huangshan Mountain East China
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Thermochemistry on Coordination Behavior of Neodymium Chloride Hydrate with Diethylammonium Diethyldithiocarbamate 被引量:2
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作者 任宜霞 焦宝娟 +4 位作者 陈三平 高胜利 赵凤起 胡荣祖 史启祯 《Journal of Rare Earths》 SCIE EI CAS CSCD 2004年第2期210-214,共5页
The complex of neodymium chloride lower hydrate with diethylammonium diethyldithiocarbamate (D-DDC) was synthesized conveniently in absolute alcohol and dry N_2 atmosphere. The title complex was identified as Et_2NH_2... The complex of neodymium chloride lower hydrate with diethylammonium diethyldithiocarbamate (D-DDC) was synthesized conveniently in absolute alcohol and dry N_2 atmosphere. The title complex was identified as Et_2NH_2[Nd(S_2CNEt_2)_4] by chemical and elemental analyses and the bonding characteristics of which was characterized by IR. The enthalpies of solution of neodymium chloride hydrate and D-DDC in absolute alcohol at 298.15 K and the enthalpies change of liquid-phase reaction of formation for Et_2NH_2[Nd (S_2CNEt_2)_4] at different temperatures were determined by microcalorimetry. On the basis of experimental and calculated results, three thermodynamic parameters (the activation enthalpy, the activation entropy and the activation free energy), the rate constant and three kinetic parameters (the apparent activation energy, the pre-exponential constant and the reaction order) of liquid-phase reaction of formation were obtained. The enthalpy change of the solid-phase title reaction at 298.15 K was calculated by a thermochemical cycle. 展开更多
关键词 physical chemistry neodymium chloride hydrate diethylammonium dithyldithiocarbamate (D-DDC) (microcalorimetric) method THERMOCHEMISTRY rare earths
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Redox chemistry of N_(4-)Fe^(2+)in iron phthalocyanines for oxygen reduction reaction 被引量:2
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作者 Anuj Kumar Ying Zhang +2 位作者 Yin Jia Wen Liu Xiaoming Sun 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2021年第8期1404-1412,共9页
A precise understanding of the redox chemistry of Nm-Mn+(like N4-Fe^(2+))systems is essential for fundamental studies and rational design of Nm-Mn+-based electrocatalysts for the oxygen reduction reaction(ORR).Herein,... A precise understanding of the redox chemistry of Nm-Mn+(like N4-Fe^(2+))systems is essential for fundamental studies and rational design of Nm-Mn+-based electrocatalysts for the oxygen reduction reaction(ORR).Herein,three different iron phthalocyanines(FePcs)adsorbed on carbon nanotubes((NH2)4FePc@CNTs,(t-Bu)4FePc@CNTs,and FePc@CNTs)were evaluated to demonstrate the effect of the electron donating power of the substituents on the Fe^(3+)/Fe^(2+)redox potential of FePc@CNTs and the role of these composites as ORR mediators in alkaline media.The Fe^(3+)/Fe^(2+)redox potential of the FePcs was found to shift towards the cathodic region upon substitution with electron-donating groups.This up-field shift in the eg-orbital leads to a lower overlap between the onset potential of the Fe^(3+)/Fe^(2+)redox couple and that of the ORR,and thus,the ORR activity decreased in the following order based on the substitution of FePc:-H>-t-Bu>-NH2. 展开更多
关键词 Iron phthalocyanines Substitution effect Oxygen reduction reaction Carbon nanotubes Activity descriptor
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Efficacious selective separation of U(Ⅵ) over Mo(Ⅵ) using novel 2,9-diamide-1,10-phenanthroline ligands: Liquid-liquid extraction and coordination chemistry 被引量:2
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作者 Taoyuan Xiu Simei Zhang +11 位作者 Peng Ren Siyan Liu Shuai Wang Hamza Shehzad Jingyang Wang Meng Zhang Guoan Ye Caishan Jiao Qunyan Wu Liyong Yuan Zhifang Chai Weiqun Shi 《Chinese Chemical Letters》 SCIE CAS CSCD 2023年第11期163-168,共6页
Uranium and molybdenum are important strategic elements. The production of ^(99)Mo and the hydrometallurgical process of uranium ore face difficult problems of separation of uranium and molybdenum.In this study, the f... Uranium and molybdenum are important strategic elements. The production of ^(99)Mo and the hydrometallurgical process of uranium ore face difficult problems of separation of uranium and molybdenum.In this study, the four phenanthroline diamide ligands were synthesized, and extraction and stripping experiments were performed under different conditions to evaluate the potential application of these ligands for separation of U(Ⅵ) over Mo(Ⅵ). With the growth of alkyl chain, the solubility of ligands could be greatly improved, and the separation effect of U(Ⅵ) over Mo(Ⅵ) gradually increased. The SF_(U/Mo) were around 10,000 at 4 mol/L HNO3. Three stripping agents were tested with the stripping efficiency of Na_(2)CO_(3)(5%) > H_(2)O > HNO_(3)(0.01 mol/L). The stripping percentages of the three stripping agents were all close to unity, indicating that the ligands had the potential to be recycled. The chemical stoichiometry of U(Ⅵ) complexes with ligands was evaluated as 1:1 using electrospray ionization mass spectrometry,ultraviolet visible spectroscopy and single-crystal X-ray diffraction. The consistency between theoretical calculation and experimental results further explains the coordination mechanism. 展开更多
关键词 Phenanthroline diamide ligand URANIUM MOLYBDENUM Solvent extraction Coordination chemistry
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ChatGPT: Application in Chemistry Education and Challenges 被引量:1
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作者 Vladimir L. Kodkin Ekaterina V. Artem’eva 《Journal of Computer and Communications》 2024年第3期196-206,共11页
The paper discusses the advancements and applications of neural networks, specifically ChatGPT, in various fields, including chemistry education and research. It examines the benefits of AI and ChatGPT, such as their ... The paper discusses the advancements and applications of neural networks, specifically ChatGPT, in various fields, including chemistry education and research. It examines the benefits of AI and ChatGPT, such as their ability to process and analyze large amounts of data, create personalized training systems, and offer problem-solving recommendations. The paper delves into practical applications, showcasing how ChatGPT can be utilised to augment chemistry learning. It provides examples of using ChatGPT for creating tests, generating multiple-choice questions, and studying chemistry in general. Concerns are voiced about the ethical and societal impact of AI development. In conclusion, it explores the exciting potential of AI to tackle challenges that may exceed human capabilities alone, paving the way for further exploration and collaboration between humans and intelligent machines. 展开更多
关键词 ChatGPT 3.5 Artificial Intelligence AI for Education Computer-Based Learning
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First Asymmetry Synthesis and Stereochemistry of Glutinone
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作者 Zhe ZHANG Zhao Ming XIONG +2 位作者 Yu Kun GUAN Guo Jun ZHENG Yu Lin LI 《Chinese Chemical Letters》 SCIE CAS CSCD 2001年第10期881-882,共2页
The first asymmetry synthesis of glutinone and its three diastereoisomers were carried out in 8 steps and the stereochemistry of this natural product was given out.
关键词 asymmetry synthesis asymmetry dihydroxylation SESQUITERPENOID
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Effect of model errors in ambient air humidity on the aerosol optical depth obtained via aerosol hygroscopicity in eastern China in the Atmospheric Chemistry and Climate Model Intercomparison Project datasets
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作者 CHANG Wenyuan 《Atmospheric and Oceanic Science Letters》 CSCD 2019年第3期162-169,共8页
This analysis of the multi-model aerosol optical depth (AOD) in eastern China using the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) datasets shows that the global models underestimate the ... This analysis of the multi-model aerosol optical depth (AOD) in eastern China using the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) datasets shows that the global models underestimate the AOD by 33% and 44% in southern and northern China, respectively, and decrease the relative humidity (RH) of the air in the surface layer to 71%–80%, which is less than the RH of 77%–92% in reanalysis meteorological datasets. This indicates that the low biases in the RH partially account for the errors in the AOD. The AOD is recalculated based on the model aerosol concentrations and the reanalysis humidity data. Improving the mean value of the RH increases the multi-model annual mean AOD by 45% in southern China and by 33% in June–August in northern China. This method of improving the AOD is successful in most of the ACCMIP models, but it is unlikely to be successful in GISS-E2-R, in which the plot of its AOD efficiency against RH strongly deviates from the rest of the models. The effect of the improvement in the modeled RH on the AOD depends on the concentration of aerosols. The shape error in the frequency distribution of the RH is likely to be more important than the error in the mean value of the RH, but this requires further research. 展开更多
关键词 Atmospheric Chemistry and Climate Model Intercomparison Project aerosol optical depth efficiency relative humidity aerosol hygroscopicity
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3D printed hybrid rocket fuels with μAl core-shell particles coated with polyvinylidene fluoride and polydopamine: Enhanced combustion characteristics 被引量:2
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作者 Qihang Chen Xiaolong Fu +6 位作者 Weitao Yang Suhang Chen Zhiming Guo Rui Hu Huijie Zhang Lianpeng Cui Xu Xia 《Defence Technology(防务技术)》 2025年第4期59-70,共12页
3D printing technology enhances the combustion characteristics of hybrid rocket fuels by enabling complex geometries. However, improvements in regression rates and energy properties of monotonous 3D printed fuels have... 3D printing technology enhances the combustion characteristics of hybrid rocket fuels by enabling complex geometries. However, improvements in regression rates and energy properties of monotonous 3D printed fuels have been limited. This study explores the impact of poly(vinylidene fluoride) and polydopamine-coated aluminum particles on the thermal and combustion properties of 3D printed hybrid rocket fuels. Physical self-assembly and anti-solvent methods were employed for constructing composite μAl particles. Characterization using SEM, XRD, XPS, FTIR, and μCT revealed a core-shell structure and homogeneous elemental distribution. Thermal analysis showed that PVDF coatings significantly increased the heat of combustion for aluminum particles, with maximum enhancement observed in μAl@PDA@PVDF(denoted as μAl@PF) at 6.20 k J/g. Subsequently, 3D printed fuels with varying pure and composite μAl particle contents were prepared using 3D printing. Combustion tests indicated higher regression rates for Al@PF/Resin composites compared to pure resin, positively correlating with particle content. The fluorocarbon-alumina reaction during the combustion stage intensified Al particle combustion, reducing residue size. A comprehensive model based on experiments provides insights into the combustion process of PDA and PVDF-coated droplets. This study advances the design of 3D-printed hybrid rocket fuels, offering strategies to improve regression rates and energy release, crucial for enhancing solid fuel performance for hybrid propulsion. 展开更多
关键词 Hybrid propulsion Regression rate 3D print fuels Micro aluminum CORE-SHELL mAl@PDA@PVDF
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Finite element analysis and experimental study on the sealing performance of low-phenyl silicone rubber sealing rings 被引量:1
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作者 Ming Gao Dongkai Li +6 位作者 Kun Liu Shuliang Xu Feng Zhao Ben Guo Anhui Pan Xiao Xie Huanre Han 《Railway Sciences》 2025年第1期123-137,共15页
Purpose–The brake pipe system was an essential braking component of the railway freight trains,but the existing E-type sealing rings had problems such as insufficient low-temperature resistance,poor heat stability an... Purpose–The brake pipe system was an essential braking component of the railway freight trains,but the existing E-type sealing rings had problems such as insufficient low-temperature resistance,poor heat stability and short service life.To address these issues,low-phenyl silicone rubber was prepared and tested,and the finite element analysis and experimental studies on the sealing performance of its sealing rings were carried out.Design/methodology/approach–The low-temperature resistance and thermal stability of the prepared lowphenyl silicone rubber were studied using low-temperature tensile testing,differential scanning calorimetry,dynamic thermomechanical analysis and thermogravimetric analysis.The sealing performance of the lowphenyl silicone rubber sealing ring was studied by using finite element analysis software abaqus and experiments.Findings–The prepared low-phenyl silicone rubber sealing ring possessed excellent low-temperature resistance and thermal stability.According to the finite element analysis results,the finish of the flange sealing surface and groove outer edge should be ensured,and extrusion damage should be avoided.The sealing rings were more susceptible to damage in high compression ratio and/or low-temperature environments.When the sealing effect was ensured,a small compression ratio should be selected,and rubbers with hardness and elasticity less affected by temperature should be selected.The prepared low-phenyl silicone rubber sealing ring had zero leakage at both room temperature(RT)and�508C.Originality/value–The innovation of this study is that it provides valuable data and experience for the future development of the sealing rings used in the brake pipe flange joints of the railway freight cars in China. 展开更多
关键词 Low-phenyl silicone rubber Sealing ring Sealing performance Finite element analysis LEAKAGE
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Radiation reduction modification of sp^(2) carbon-conjugated covalent organic frameworks for enhanced photocatalytic chromium(Ⅵ) removal 被引量:1
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作者 Shouchao Zhong Yue Wang +6 位作者 Mingshu Xie Yiqian Wu Jiuqiang Li Jing Peng Liyong Yuan Maolin Zhai Weiqun Shi 《Chinese Chemical Letters》 2025年第5期277-282,共6页
A sp^(2) carbon-conjugated covalent organic framework (BDATN) was modified through γ-ray radiation reduction and subsequent acidification with hydrochloric acid to yield a novel functional COF (named rBDATN-HCl) for ... A sp^(2) carbon-conjugated covalent organic framework (BDATN) was modified through γ-ray radiation reduction and subsequent acidification with hydrochloric acid to yield a novel functional COF (named rBDATN-HCl) for Cr(Ⅵ) removal.The morphology and structure of rBDATN-HCl were analyzed and identified by SEM,FTIR,XRD and solid-state13C NMR.It is found that the active functional groups,such as hydroxyl and amide,were introduced into BDATN after radiation reduction and acidification.The prepared rBDATN-HCl demonstrates a photocatalytic reduction removal rate of Cr(Ⅵ) above 99%after 60min of illumination with a solid-liquid ratio of 0.5 mg/mL,showing outstanding performance,which is attributed to the increase of dispersibility and adsorption sites of r BDATN-HCl.In comparison to the cBDATN-HCl synthesized with chemical reduction,rBDATN-HCl exhibits a better photoreduction performance for Cr(Ⅵ),demonstrating the advantages of radiation preparation of rBDATN-HCl.It is expected that more functionalized sp^(2) carbon-conjugated COFs could be obtained by this radiation-induced reduction strategy. 展开更多
关键词 Covalent organic framework Gamma radiation Photocatalytic reduction CHROMIUM Water purification
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Efficient Electroreduction of CO_(2)to CH_(4)Over Amino Acid-Modified Copper Under Acidic Conditions 被引量:1
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作者 Yichi Zhang Yajuan Wan +8 位作者 Min Wang Xia Bai Zijun Zhang Yingxuan Liu Shuaiqiang Jia Mingyuan He Chunjun Chen Haihong Wu Buxing Han 《Carbon and Hydrogen》 2025年第1期5-9,共5页
Electroreduction of CO_(2) into CH_(4) under acidic conditions is a promising strategy for CO_(2) utilization,which allows for high CO_(2) conversion efficiency.However,the selectivity of CH_(4) is low because the hyd... Electroreduction of CO_(2) into CH_(4) under acidic conditions is a promising strategy for CO_(2) utilization,which allows for high CO_(2) conversion efficiency.However,the selectivity of CH_(4) is low because the hydrogen evolution reaction is enhanced under acidic conditions.Here,we report that the CO_(2) can be efficiently reduced into CH_(4) over a Cu catalyst by modifying with a glutamic acid molecule under acidic conditions.The CH_(4) Faradaic efficiency can reach 62.9% with a current density of 450 mA cm^(-2).Meanwhile,a single-pass carbon efficiency of 48.1% toward CH_(4) is achieved.Experiments revealed that the glutamic acid molecule can enhance the concentration of Kt on the surface of Cu,which can suppress the HER and promote CO_(2) reduction,resulting in high selectivity of CH_(4) under acidic conditions. 展开更多
关键词 carbon dioxide ELECTROCHEMICAL green chemistry METHANE molecular modification
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