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One-cycles on Gushel-Mukai fourfolds and the Beauville-Voisin filtration

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Science china Mathematics 2024年第4期67卷 713-732页

作者： Ruxuan zhang School of Mathematical Sciences Fudan UniversityShanghai 200438China

We prove that the invariant locus of the involution associated with a general double EisenbudPopescu-Walter(EPW)sextic is a constant cycle surface and introduce a filtration on ch1of a Gushel-Mukai *** verify the sheaf/cycle correspondence for sheaves supported on low-degree rational curves,parallel to the case of cubic fourfolds of Shen-Yin’s work.

关键词： Beauville-Voisin ltration irreducible holomorphic symplectic variety Gushel-Mukai fourfold

Compositional evolution for mixed aerosols containing gluconic acid and typical nitrate and the effect of multiply factors on hygroscopicity

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Journal of Environmental Sciences 2024年第5期139卷 206-216页

作者： Yue Zhu Shufeng Pang Yunhong zhang School of chemistry and chemical Engineering Beijing Institute of TechnologyBeijing 100081China

The aging process of atmospheric aerosols usually leads to a mixture of inorganic salts and organic compounds of anthropogenic *** organic compounds,polyhydroxy organic acids are important components,however,the study on composition and hygroscopic properties of the mixture containing inorganics and polyhydroxy organic acids is *** this study,gluconic acid,the proxy of polyhydroxy organic acids,is mixed with the representative nitrate(Mg(NO_(3))_(2),Ca(NO_(3))_(2))to form ***-FTIR and optical microscopy are employed to study the component changes and hygroscopicity as a function of relative *** relative humidity fluctuates,the FTIR-ATR spectra display that the internal mixed gluconic acid(ch_(2)(ch)_(4)(OH)_(5)COOH)and nitrate can react to release acidic gases,forming relevant gluconate and further affecting the *** specific presentation is particles cannot be recovered to their original size after the dehydration-hydration process and there will be some disparities in GF for mixed *** the gluconic acid-Ca(NO_(3))_(2)/Mg(NO_(3))_(2)mixtures with molar ratios of 1:1,higher degree of reaction resulting in the production of large amounts of gluconate should be responsible to the lower hygroscopicity compared to ZSR *** 1:2 gluconic acid-nitrate mixed systems(with higher nitrate content),the hygroscopicity of mixtures are higher than the ZSR prediction.A possible reason could be‘salt-promoting effect’on the organic fractions of the surplus inorganic salt in the *** data can improve the chemical composition list evaluation,in turn hygroscopic properties and phase state of atmospheric aerosol,and then the climate effect.

关键词： Hygroscopicity Gluconic acid Reaction ZSR simulation Size growth factors

Significant contribution of carbonyls to atmospheric oxidation capacity(AOC)during the winter haze pollution over North china Plain

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Journal of Environmental Sciences 2024年第5期139卷 377-388页

作者： Xue Yang Gen zhang Guang Pan Guolan Fan Houyong zhang Xuan Ge Mingyue Du School of Municipal and Environmental Engineering Shandong Jianzhu UniversityJi’nan 250101China State Key Laboratory of Severe Weather&Key Laboratory of Atmospheric chemistry of china Meteorological Administration Chinese Academy of Meteorological SciencesBeijing 100081China Shandong Jinan Ecological Environment Monitoring Center Ji’nan 250101China

Atmospheric carbonyl compounds play significant roles in the cycling of radicals and have exhibited surprisingly high levels in winter that were well correlated to particulate matter,for which the reason have not been clearly *** we measured carbonyl compounds and other trace gasses together with PM_(2.5)over urban Jinan in North china Plain during the *** higher carbonyl concentrations(average:14.63±4.21 ppbv)were found during wintertime haze pollution,about one to three-times relative to those on nonhaze days,with slight difference in chemical composition except formaldehyde(HchO).HchO(3.68 ppbv),acetone(3.17 ppbv),and acetaldehyde(ch_3chO)(2.83 ppbv)were the three most abundant species,accounting for~75% of the total carbonylson both haze and non-haze *** from observational-based model(OBM)with atmospheric oxidation capacity(AOC)indicated that AOC significantly increased with the increasing carbonyls during the winter haze *** photolysis have supplied key oxidants such as RO_(2) and HO_(2),and thereby enhancing the formation of fine particles and secondary organic aerosols,elucidating the observed haze-carbonyls *** variation with carbonyls exhibiting peak values at early-noon and night highlighted the combined contribution of both secondary formation and primary diesel-fuel sources.1-butene was further confirmed to be the major precursor for *** study confirms the great contribution of carbonyls to AOC,and also suggests that reducing the emissions of carbonyls would be an effective way to mitigate haze pollution in urban area of the NCP region.

关键词： Carbonyls Haze Observation-based model Source apportionment Atmospheric oxidation capacity

Initial precursor reaction mechanism of CVD-HfC coating based on density functional theory

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chinese Journal of Aeronautics 2024年第7期37卷 511-521页

作者： Yunzhou LIN Yulei zhang Yanqin FU Jian zhang Jing’an KONG Ruicong chEN State Key Laboratory of Solidification Processing Carbon/Carbon Composites Research CenterNorthwestern Polytechnical UniversityXi’an 710072China Henan Key Laboratory of High Performance Carbon Fiber Reinforced Composites Carbon Matrix Composites Research InstituteHenan Academy of SciencesZhengzhou 450046China

Recently,the preparation of ultra-high temperature HfC ceramic coating has gained significant attention,particularly through the application of the HfCl_(4)-ch_(4)-H_(2)-Ar system via chemical Vapor Deposition(CVD),which has been found widely applied to C/C ***,an analysis of the reactions that occur in the initial stage of the CVD-HfC coating process is presented using Density Functional Theory(DFT)and Transition State Theory(TST)at the B3LYP/Lanl2DZ *** results reveal that HfCl4 can only cleave to produce hypochlorite,which will further react with methyl to synthesize intermediates to form *** to the analysis of the energy barrier and reaction constant,HfCl preferentially reacts with methyl groups to form complex adsorptive intermediates at 1573 *** a C—Hf bond production energy of 212.8 kcal/mol(1 kcal=4.18 kJ),the reaction rate constant of HfCl+ch is calculated to be 2.15×10^(-18) cm^(3)/s at 1573 ***,both the simulation and experimental results exhibit that the upward trend of reaction rate constants with temperature is also consistent with the deposition rate,indicating that the growth curve of the reaction rate constants tends to flatten *** proposed reaction model of the precursor’s decomposition and reconstruction during deposition process has significant implication for the process guidance.

关键词： Carbon composite HfC coating chemical vapor deposition Density functional theory Precursor reaction mechanism

Investigating the effect of volatility on the hygroscopicities of acetate nanoparticle aerosols by surface plasmon resonance microscopy

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Journal of Environmental Sciences 2024年第4期138卷 167-178页

作者： Bo Yang Zhibo Xie Jianguo Liu Huaqiao Gui Jiaoshi zhang Xiuli Wei Zetao Fan Douguo zhang Key Laboratory of Environmental Optics and Technology Anhui Institute of Optics and Fine MechanicsHefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China University of Science and Technology of china Hefei 230026China CAS Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China Advanced Laser Technology Laboratory of Anhui Province Department of Optics and Optical EngineeringUniversity of Science and Technology of ChinaHefei 230026China

Under high relative humidity(RH)conditions,the release of volatile components(such as acetate)has a significant impact on the aerosol *** this work,one surface plasmon resonance microscopy(SPRM)measurement system was introduced to determine the hygroscopic growth factors(GFs)of three acetate aerosols separately or mixed with glucose at different *** Ca(ch_(3)COO)_(2) or Mg(ch_(3)COO)_(2) aerosols,the hygroscopic growth trend of each time was lower than that of the previous time in three cyclic humidification from 70% RH to 90% RH,which may be due to the volatility of acetic acid leading to the formation of insoluble hydroxide(Ca(OH)_(2) or Mg(OH)_(2))under high RH *** the third calculated GF(using the Zdanovskii-Stokes-Robinson method)for Ca(ch_(3)COO)_(2) or Mg(ch_(3)COO)_(2) in bicomponent aerosols with 1:1 mass ratio were 3.20% or 5.33% lower than that of the first calculated GF at 90% *** calculated results also showed that the hygroscopicity change of bicomponent aerosol was negatively correlated with glucose content,especially when the mass ratio of Mg(ch_(3)COO)_(2) to glucose was 1:2,the GF at 90% RH only decreased by4.67% after three cyclic *** coupled plasma atomic emission spectrum(ICP-AES)based measurements also indicated that the changes of Mg^(2+)concentration in bicomponent was lower than that of the *** results of this study reveal thatduring the efflorescence transitions of atmospheric nanoparticles,the organic acids diffusion rate may be inhibited by the coating effect of neutral organic components,and the particles aging cycle will be prolonged.

关键词： Hygroscopic growth Volatility Acetate aerosols Nanoparticle aerosol Surface plasmon resonance

Highly selective photocatalytic oxidation of methane to methyl hydroperoxide

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Nano Research 2024年第4期17卷 2473-2480页

作者： chunling Bo Li zhang Xiaolong Liu Huaiqiu chang Yingxue Sun Xinyi zhang Ting Tan Lingyu Piao National Center for Nanoscience and Technology Beijing 100190China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China University of chinese Academy of Sciences Beijing 100049China State Key Laboratory of chemical Resource Engineering Beijing University of Chemical TechnologyBeijing 100029China

Partial oxidation of methane into primary oxidation products with high value remains a *** this work,photocatalytic oxidation of methane(ch_(4))with high methyl hydroperoxide(ch_(3)OOH)selectivity is achieved using pure titanium oxide(TiO_(2))without any cocatalyst at room temperature and atmospheric *** ch_(3)OOH production rate can reach up to 2050±88μmol·g^(-1)·h^(-1) at pH≈7.0 with 100%selectivity in the liquid *** stable reaction cycle can reach more than 30 *** low-cost system achieves superior ch_(4) conversion activity and selectivity compared with similar *** energy of hydrogen peroxide(H_(2)O_(2))to adsorbed hydroperoxyl radical(^(*)OOH)has a significantly lower reaction energy than conversion to adsorbed hydroxyl radical(*OH)on the(210)surface of the TiO_(2).The^(*)OOH preferentially combines with methyl radical(·ch_(3))to form the most energetically favorable ch_(3)*** mild oxidative environment of this system prevents the reduction of ch_(3)OOH to ch_(3)OH or over-oxidation of ch_(4),which ensures the final ch_(3)OOH with high selectivity and *** work provided a low-cost but highly efficient method to achieve partial oxidation with superior selectivity,i.e.,to convert ch_(4) into high-value chemicals.

关键词： photocatalytic methane oxidation methyl hydroperoxide titanium oxide

Efficient adsorption separation of methane from C_(2)-C_(3) hydrocarbons in a Co(Ⅱ)-nodes metal-organic framework

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chinese Journal of chemical Engineering 2024年第5期69卷 192-198页

作者： Jie zhang Xingzhe Guo Bing Lin Guangzu Xiong Hanshuang Wang Min zhang Liwen Fan Bingwen Li Shuisheng chen Department of chemistry and chemical Engineering Taiyuan Institute of TechnologyTaiyuan 030008China Engineering Research Center of Oligosaccharides Fuyang Normal UniversityFuyang 236041China Shandong Key Laboratory of Biophysics Institute of BiophysicsDezhou UniversityDezhou 253023China

Methane(ch_(4))as a substitute for other mineral fuels plays a crucial role in reducing energy consumption and preventing environmental *** present study employs a solvothermal method to fabricate a porous framework Co-metal-organic framework(Co-MOF)containing two distinct secondary building units(SBUs):an anionic[Co_(2)(μ_(2)-OH)(COO)_(4)(H_(2)O)]and a neutral[CoN_(2)(COO)_(2)].Notably,within the anionic SBUs,the coordinated water molecules induce the generation of divergent unsaturated Co(Ⅱ)centers in the unidirectional porous channels,thereby creating open metal *** adsorption performance of Co-MOF towards pure component gases was systematically *** results demonstrated that Co-MOF exhibits superior adsorption capacity for C_(2)-C_(3) hydrocarbons compared to ch_(4),which offers the potential for efficient adsorption and separation of ch_(4) from C_(2)-C_(3) *** gas selectivity separation ratios of Co-MOF for C_(2)H_(6)/ch_(4) and C_(3)H_8/ch_(4) were calculated using the ideal adsorbed solution theory method at 273/298 K and 0.1 *** results revealed that Co-MOF achieved remarkable equilibrium separation selectivity for ch_(4) and C_(2)-C_(3) hydrocarbon gases among non-modified MOFs,signifying the potential of the synthesized Co-MOF for efficient recovery and purification of ch_(4) from C_(2)-C_(3) *** experiments further demonstrate the ability of Co-MOF to purify methane from C_(2)-C_(3) hydrocarbons in practical gas separation ***,molecular simulation calculations further substantiate the propensity of anionic SBUs to interact with C_(2)-C_(3) hydrocarbon *** study provides a novel paradigm for the development of porous MOF materials in the application of gas mixture separation.

关键词： Co-MOF Separation hydrocarbons Dynamic breakthrough curves Molecular simulations adsorbent Monte Carlo simulation

Quantification of Central and Eastern china's atmospheric ch_(4) enhancement changes and its contributions based on machine learning approach

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Journal of Environmental Sciences 2024年第4期138卷 236-248页

作者： Xinyue Ai cheng Hu Yanrong Yang Leying zhang Huili Liu Junqing zhang Xin chen Guoqiang Bai Wei Xiao College of Biology and the Environment Joint Center for sustainable Forestry in Southern ChinaNanjing Forestry UniversityNanjing 210037China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD) Nanjing University of Information Science&TechnologyNanjing 210044China Guang’an Vocational&Technical College Guangan 638550China HuaNan Meteorological Administration Huanan 154400China

Methane is the second largest anthropogenic greenhouse gas,and changes in atmospheric methane concentrations can reflect the dynamic balance between its emissions and ***,the monitoring of ch_(4) concentration changes and the assessment of underlying driving factors can provide scientific basis for the government’s policy making and *** is the world’s largest emitter of anthropogenic ***,due to the lack of ground-based observation sites,little work has been done on the spatial-temporal variations for the past decades and influencing factors in china,especially for areas with high anthropogenic emissions as Central and Eastern *** to quantify atmospheric ch_(4) enhancements trends and its driving factors in Central and Eastern china,we combined the most up-to-date TROPOMI satellite-based column ch_(4)(xch_(4))concentration from 2018 to 2022,anthropogenic and natural emissions,and a random forest-based machine learning approach,to simulate atmospheric xch_(4) enhancements from 2001 to *** results showed that(1)the random forest model was able to accurately establish the relationship between emission sources and xch_(4) enhancement with a correlation coefficient(R^(2))of 0.89 and a root mean-square error(RMSE)of 11.98 ppb;(2)The xch_(4) enhancement only increased from 48.21±2.02 ppb to 49.79±1.87 ppb from the year of 2001 to 2018,with a relative change of 3.27%±0.13%;(3)The simulation results showed that the energy activities and waste treatment were the main contributors to the increase in xch_(4) enhancement,contributing 68.00% and 31.21%,respectively,and the decrease of animal ruminants contributed-6.70% of its enhancement trend.

关键词： TROPOMI Methane column concentrations Anthropogenic sources Random Forest model

Heterocatalytic ethylene methoxycarbonylation via a pseudo-hydride pathway over Pt_(1)/MoS_(2)

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Science china chemistry 2024年第8期67卷 2427-2428页

作者： Bo-Hang Zhao Bin zhang Institute of Molecular Plus Department of ChemistrySchool of ScienceTianjin UniversityTianjin 300072China

Ethylene (C2H4) methoxycarbonylation (EMC) with CO and methanol (ch3OH) to methyl propanoate (MP) is industrially important due to its 100% atom efficiency [1].However, the heavy reliance on homogeneous Pd-based catalysts and strong acid media over commercial EMC processes still causes economic and environmental concerns [2]. At present, supported single-atom catalysts (SACs) can serve as bridges for accessing homogeneous catalysts in traditional heterogeneous catalytic processes.

关键词： processes. catalytic hydride