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Variability of PM_(2.5) and O_(3) concentrations and their driving forces over Chinese megacities during 2018-2020

Journal of Environmental Sciences 2023年第2期124卷 1-10页

作者： Tianyi Xu chengxin Zhang Cheng Liu Qihou Hu School of Environmental Science and Optoelectronic Technology University of Science and Technology of ChinaHefei 230026China Department of Precision Machinery and Precision Instrumentation University of Science and Technology of ChinaHefei 230026China Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China Key Laboratory of Environmental Optics and Technology Anhui Institute of Optics and Fine MechanicsChinese Academy of SciencesHefei 230031China Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes University of Science and Technology of ChinaHefei 230026China

Recently,air pollution especially fine particulate matters(PM_(2.5))and ozone(O_(3))has become a severe issue in *** this study,we first characterized the temporal trends of PM_(2.5) and O_(3) for Beijing,Guangzhou,Shanghai,andWuhan respectively during *** annual mean PM2.5 has decreased by 7.82%-33.92%,while O_(3) concentration showed insignificant variations by-6.77%-4.65%during *** generalized additive models(GAMs)were implemented to quantify the contribution of individual meteorological factors and their gas precursors on PM_(2.5) and O_(3).On a short-term perspective,GAMs modeling shows that the daily variability of PM_(2.5) concentration is largely related to the variation of precursor gases(R=0.67-0.90),while meteorological conditions mainly affect the daily variability of O_(3) concentration(R=0.65-0.80)during *** impact of COVID-19 lockdown on PM_(2.5) and O_(3) concentrations were also quantified by using *** the 2020 lockdown,PM_(2.5) decreased significantly for these megacities,yet the ozone concentration showed an increasing trend compared to *** GAMs analysis indicated that the contribution of precursor gases to PM_(2.5) and O_(3) changes is 3-8 times higher than that of meteorological *** general,GAMsmodeling on air quality is helpful to the understanding and control of PM2.5 and O3 pollution in China.

关键词： Air pollution PM_(2.5)and O_(3)trends Meteorology COVID-19 lockdown

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A Highly Active Pd（Ⅱ） Complex with 1-Tritylimidazole Ligand for Suzuki-Miyaura and heck Coupling Reactions

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Chinese Journal of Chemistry 2016年第10期34卷 1048-1052页

作者： chengxin Liu Guiyan Liu Hongkun Zhao Tianjin Key Laboratory of Structure and Performance for Functional Molecules Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry(Tianjin Normal University) Ministry of Education College of Chemistry Tianjin Normal UniversityTianjin 300387China

A [Pd（1-tritylimidazole）2Cl2] complex was synthesized and characterized by IH and 13C NMR spectroscopy, elemental analysis, and X-ray crystallography. The X-ray analysis confirmed that the Pd（II） has a four-coordinated square planar structure. The palladium complex was used to carry out Suzuki-Miyaura coupling reactions of aryl chlorides with a variety of phenylboronic acids in i-PrOH-H20 （1 ： 1, V ： V） at room temperature and heck coupling reactions of aryl halides with methyl acrylate in DMF at 110℃. High yields of the cross-coupling products were obtained.

关键词： palladium 1-tritylimidazole Suzuki-Miyaura coupling reaction heck coupling reaction

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Transparent ultrathin SiO_(2) nanowire aerogel displaying novel properties when interacting with water:A promising versatile functional platform

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Fundamental Research 2023年第1期3卷 118-125页

作者： Jingbo he Churong Ma Jin Yang Xiaobin Zou Bo Sun Yong Sun chengxin Wang State Key Laboratory of Optoelectronic Materials and Technologies School of Materials Science and EngineeringSun Yat-sen(Zhongshan)UniversityGuangzhou 510275China Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications Institute of Photonics TechnologyJinan UniversityGuangzhou 511443China

With low density,high porosity,and outstanding physicochemical stability,ceramic nanowire aerogels and sponges exhibit various interesting ***,an ultrathin silica nanowire aerogel(SiO_(2)NWsA)was achieved via a facile chemical vapor deposition *** addition to good mechanical and thermal performances,properties resulting from active water-aerogel interactions are revealed,i.e.,outstanding transparency,strong capillary effect,enhanced compressive strength(a reversible strain of∼62%),switchable wettability and robust shape retention ability when filled with *** physical mechanism related to these interesting properties is demonstrated basically according to its unique features(distinctly reduced nanowire diameter,enriched nanoscopic gap channels,and reinforced network).To demonstrate the superiority,an advantageous solar vapor generation system(hydrophilic NWs-A/reduced graphene oxide(rGO)/hydrophobic NWs-A)was obtained by integrating these favorable characteristics,giving rise to remarkably promoted vapor evaporation rate and energy efficiency compared to the rGO hydrophobic NWs-A *** results contribute to the structural design and functional exploration of nanowire aerogels.

关键词： Silica aerogel Nanowire aerogel Capillary effect Flexibility Transparency

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Numerical simulation of groundwater under complex karst conditions and the prediction of roadway gushing in a coal mine:a case study in the Guang'an Longtan Reservoir in Sichuan Province, China

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Acta Geochimica 2016年第1期35卷 72-84页

作者： Jiang chengxin Shi Huapeng Li Ya Yu Hongming Faculty of Engineering China University of Geosciences

Numerical simulation of groundwater in karst areas has long been restricted by the difficulty of generalizing the hydrogeological conditions of reservoirs and of determining the relevant parameters due to the anisotropy and discontinuity of the karst water-bearing media in these areas. In this study, we used the Guang'an Longtan Coal mine in Sichuan as an example, and generalized the complex hydrogeological conditions in the reservoir area. A finite element numerical flow model was used to simulate current and future scenarios of roadway gushing at the bottom of the coal mine at pile number 1 + 700 m. The results show that the roadway section corresponding to valleys has a gushing quantity of 4323.8–4551.25 m^3/d before impoundment. Modeled water inflow after impoundment increased to 1.6 times the water inflow before impoundment, which threatens the impoundment as well as the roadway's normal operation. Therefore, roadway processing measures are needed to guarantee the safety of the impoundment and of the mining operation.

关键词： Karst reservoir Roadway gushing Numerical simulation Hydrogeological conditions generalization

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Influence of Chironomid Larvae on oxygen and nitrogen fluxes across the sediment-water interface(Lake Taihu,China)

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Journal of Environmental Sciences 2013年第5期25卷 978-985页

作者： Jingge Shang Lu Zhang Chengjun Shi chengxin Fan State Key Laboratory of Lake Science and Environment Nanjing Institute of Geography and LimnologyChinese Academy of Sciences University of Chinese Academy of Sciences Jiangsu Xuyi Economic Development Zone Planning Construction Bureau

The microscale distribution of oxygen,the nitrogen flux and the denitrification rates in sediment inhabited by chironomid larvae（Tanypus chinensis） were measured in eutrophic Lake Taihu,*** presence of the chironomids in the sediment increased the oxygen diffusional flux from 10.4 ± 1.4 to 12.7 ± 2.5 mmol O 2 /（m 2 ·day）.The burrows of the larvae represented ＂hot spots＂ and strongly influenced the nitrogen cycles and diagenetic activity in the *** results indicate that the bioturbation effects of Tanypus chinensis chironomid larvae increased the capacity of the sediment as a sink for nitrate and a source for *** influx and ammonium outflux were increased 8.8 and 1.7 times,*** bioturbation,the amount of nitrate consumed was greater than the amount of ammonium *** total denitrification rate was also enhanced from 0.76 ± 0.34 to 5.50 ± 1.30 mmol N/（m 2 ·day）.The net effect was that the bioturbated sediments acted as a net sink for inorganic nitrogen under direct and indirect bioturbation effects compared to the control.

关键词： bioturbation chironomid larvae oxygen nitrogen Lake Taihu

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Research advances on electrode materials for solid oxide electrolysis cells

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Progress in Natural Science:Materials International 2023年第3期33卷 309-319页

作者： Hongyuan Su Duoli Wu chengxin Li Changjiu Li Chao Zhang College of Mechanical Engineering Yangzhou University State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and Engineering Xi'an Jiaotong University

Solid oxide electrolytic cell(SOEC) is an energy conversion device that transfers electrical energy into chemical energy. It has garnered significant attention due to its high efficiency and thick current density. The oxygen evolution reaction(OER) and the hydrogen evolution reaction(heR) are two crucial half-reactions of SOEC, while both require excellent electrochemical performance under high-temperature and high-humidity ***, high catalytic activity and good stability of electrode materials are crucial for the practical application of SOEC. The perovskite structure of the oxygen electrodes has outstanding OER activity, while metal ceramic and metal oxide hydrogen electrodes possess good redox properties. This article firstly demonstrates the influence of the physical and electrochemical properties of electrode materials on the performance of SOEC, then illustrates the optimization strategies for electrode materials to improve electrolysis efficiency and extend service ***, the research priorities for the future development of electrode material are summarized.

关键词： Solid oxide electrolysis cell Oxygen electrode Hydrogen electrode Perovskite oxide

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A new method of enhancing reliability for transmission expansion planning

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Journal of Modern Power Systems and Clean Energy 2014年第4期2卷 341-349页

作者： chengxin LI Guo CheN Junyong LIU The School of Electrical Engineering and Information Sichuan UniversityChengdu 610065China The School of Electrical and Information Engineering The University of SydneyCamperdownNSW 2006Australia

The reliability plays a significant role in power systems and it is an important objective or constraint in transmission expansion ***,a DC optimization model was proposed to calculate the maximum arrival power at each load *** to the network flow method,DC model is closer to the actual power flow and it is able to obtain more realistic reliability assessment ***,a novel sensitivity index(SI)was also proposed to choose the most effective line so as to enhance the nodal and/or system *** Monte Carlo simulation is used to simulate the system components *** improved reliability evaluation method and SI can be used for transmission expansion planning or maintenance *** are performed using 6-bus system derived from the Garver’s system and the IEEE 10-machine 39-bus *** results show the effectiveness of the method.

关键词： Probabilistic reliability evaluation Sensitivity analysis Monte Carlo simulation DC model

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Influence of Atmospheric Plasma-Sprayed Composite Cathode on the Performance of Solid Oxide Fuel Cells

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稀有金属材料与工程 2012年第S1期41卷 448-452页

作者： Li chengxin Yang Guanjun Li Changjiu Xi An Jiao Tong Univ State Key Lab Mech Behav Mat Xian 710049 Peoples R China

Ni-Al2O3 cermet supported tubular solid oxide fuel cells(SOFCs)with different cathodes were fabricated by thermal *** anode,electrolyte and cathode were deposited by atmospheric plasma spraying(APS)aimed at reducing the manufacturing cost of *** porous composite cathodes of lanthanum strontium manganite(LSM)and yttria-stabilized zirconia(YSZ),lanthanum strontium cobalt oxide(LSC)and YSZ,LSC and scandia-stabilized zirconia(ScSZ)were prepared to investigate influence of cathode constitutions on the cell's *** electrode polarization can be improved through using a composite *** maximum power density of the cell with APS YSZ electrolyte and LSC/ScSZ composite cathode is increased about 12%than pure LSM *** maximum output power density of the cell with APS ScSZ electrolyte and LSC/ScSZ composite cathode reaches 1.0 W/cm 2 at 1000 o *** further optimization of the performance of plasma-sprayed composite cathode can be made through improving the interface contact between YSZ electrolyte and composite cathode.

关键词： solid oxide fuel cell plasma spraying,composite cathode lanthanum strontium manganate lanthanum strontium cobalt oxide

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Dynamic Color Transform Networks for Wheat head Detection

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Plant Phenomics 2022年第1期4卷 395-408页

作者： chengxin Liu Kewei Wang Hao Lu Zhiguo Cao Key Laboratory of Image Processing and Intelligent Control Ministry of EducationSchool of Artificial Intelligence and AutomationHuazhong University of Science and TechnologyWuhanChina

Wheat head detection can measure wheat traits such as head density and head *** wheat breeding largely relies on manual observation to detect wheat heads,yielding a tedious and inefficient *** emergence of affordable camera platforms provides opportunities for deploying computer vision(CV)algorithms in wheat head detection,enabling automated measurements of wheat *** wheat head detection,however,is challenging due to the variability of observation circumstances and the uncertainty of wheat head *** this work,we propose a simple but effective idea—dynamic color transform(DCT)—for accurate wheat head detection.

关键词： Wheat breeding wheat

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Effects of heat Treatment on Luminescence of Er-Doped Silicon-Rich SiO2 Prepared by rf Co-sputtering

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Chinese Physics Letters 2004年第7期21卷 1333-1336页

作者： ZHANGChang-Shen XIAOHai-Bo CheNZhi-Jun chengxin-Li ZHANGFeng IonBeamLaboratory ShanghaiInstituteofMicrosystemandInformationTechnologyChineseAcademyofSciencesShanghai200050

Er-doped silicon-rich SiO_2 thin films were prepared by an rf co-sputtering method, followed by thermal annealing at 700-1200 ℃ for 30 min. The microstructure is studied by transmission electron microscopy (TEM) and x-ray diffraction (XRD). When the films are annealed at T > 900 ℃, silicon nanocrystals (nc-Si) enveloped by amorphous silicon (α-Si) can be observed. The thermal quenching behaviour at λ = 1.535 μm and its relation with the annealing temperature are also investigated. With the increasing annealing temperature, the portion of α-Si and the intensity quenching both decrease. Efficient luminescence from Er ions and weak intensity thermal quenching can be obtained from the sample annealed at 1100 ℃. The role of α-Si in the non-radiative processes at T > 100 K is discussed.

关键词： Condensed matter: electrical magnetic and optical Surfaces interfaces and thin films Condensed matter: structural mechanical & thermal

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