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Chinese Journal of Chemical Engineering 2024年第5期69卷 1-12页

作者： Zhekun Chen Weitong Pan Longfei Tang xueli Chen Fuchen Wang Engineering Research Center of Resource Utilization of Carbon-containing Waste with Carbon Neutrality Ministry of EducationEast China University of Science and TechnologyShanghai 200237China Key Laboratory of Pressure Systems and Safety Ministry of EducationEast China University of Science and TechnologyShanghai 200237China

Ensuring the consistency of electrode structure in proton-exchange-membrane fuel cells is highly desired yet challenging because of wide-existing and unguided cracks in the microporous layer(mPL). The first thing is to evaluate the homogeneity of mPL with cracks quantitatively. This paper proposes the homogeneity index of a full-scale mPL with an area of 50 cm~2, which is yet to be reported in the literature to our knowledge. Besides, the effects of the carbon material and surfactant on the ink and resulting mPL structure have been studied. The ink with a high network development degree produces an mPL with low crack density, but the ink with high PDI produces an mPL with low crack homogeneity. The polarity of the surfactant and the non-polarity of polytetrafluoroethylene(PTFE) are not mutually soluble,resulting in the heterogeneous PTFE distribution. The findings of this study provide guidelines for mPL fabrication.

关键词： Proton-exchange-membrane fuel cell microporous layer Crack density Crack homogeneity Polytetrafluoroethylene distribution Surfactant

The storage and utilization of carbohydrates in response to elevation mediated by tree organs in subtropical evergreen broad-leaved forests

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Forest Ecosystems 2024年第1期11卷 52-61页

作者： Bin Xu xueli Jiang Yingying Zong G.Geoff Wang Fusheng Chen Zhenyu Zhao Xiangmin Fang Key Laboratory of National Forestry and Grassland Administration on Forest Ecosystem Protection and Restoration of Poyang Lake Watershed College of ForestryJiangxi Agricultural UniversityNanchang330045China Jiulianshan National observation and Research Station of Chinese Forest Ecosystem College of ForestryJiangxi Agricultural UniversityNanchang330045China Department of Forestry and Environmental Conservation Clemson UniversityClemsonSC29634USA

Global climate change can affect tree growth and carbon sink function by influencing plant carbohydrate synthesis and utilization,while elevation can be used as an ideal setting under natural conditions to simulate climate change *** effect of elevation on tree growth may depend on organ ***,the allocation patterns of nonstructural and structural carbohydrates(NSCs and SCs,respectively)in different tree organs and their response to elevation remain *** selected four dominant tree species,Schima superba,Castanopsis eyrei,Castanopsis fargesii and michelia maudiae,along an elevation gradient from 609 to 1,207 m in subtropical evergreen broad-leaved forests and analyzed leaf,trunk,and fine root NSCs,carbon(C),nitrogen(N)and phosphorus(P)concentrations and the relative abundance of *** NSCs increased initially and then decreased,and trunk NSCs increased with increasing ***,root NSCs decreased with increasing *** relative abundance of SCs in leaves and trunks decreased,while the relative abundance of root SCs increased with increasing *** significant correlations between SCs and NSCs in leaves were detected,while there were negative correlations between SCs and NSCs in trunks,roots,and all *** partitioning analysis indicated that plant C/N and C/P were the main predictors of changes in SCs and *** results suggest that tree organs have divergent responses to elevation and that increasing elevation will inhibit the aboveground part growth and enhance the root growth of trees.A tradeoff between the C distribution used for growth and storage was confirmed along the elevation gradient,which is mainly manifested in the"sink"organs of *** results provide insight into tree growth in the context of global climate change scenarios in subtropical forest ecosystems.

关键词： Nonstructural carbohydrates Structural carbohydrates Elevation Subtropical evergreen broad-leaved forests Tree organs

Physical activity, long-term fine particulate matter exposure and type 2 diabetes incidence: A prospective cohort study

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Chronic Diseases and Translational medicine 2024年第3期10卷 205-215页

作者： Qian Li Fangchao Liu Keyong Huang Fengchao Liang Chong Shen Jian Liao Jianxin Li Chenxi Yuan xueli Yang Jie Cao Shufeng Chen Dongsheng Hu Jianfeng Huang Yang Liu Xiangfeng Lu Dongfeng Gu Department of Epidem.ology Center for Global HealthSchool of Public HealthNanjing Medical UniversityNanjingJiangsuChina Department of Epidem.ology Fuwai HospitalNational Center for Cardiovascular DiseasesChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina Key Laboratory of Cardiovascular Epidem.ology Chinese Academy of Medical SciencesBeijingChina School of Public Health and Emergency management Southern University of Science and TechnologyShenzhenGuangdongChina Research Units of Cohort Study on Cardiovascular Diseases and Cancers Chinese Academy of Medical SciencesBeijingChina Tianjin Key Laboratory of Environment Nutrition and Public HealthDepartment of Occupational and Environmental HealthSchool of Public HealthTianjin Medical UniversityTianjinChina Department of Epidem.ology and Health Statistics College of Public HealthZhengzhou UniversityZhengzhouHenanChina Department of Epidem.ology and Health Statistics School of Public HealthShenzhen University Health Science CenterShenzhenGuangdongChina Gangarosa Department of Environmental Health Rollins School of Public HealthEmory UniversityAtlantaGeorgiaUSA

Background: Despite the adverse effects of ambient fine particulate matter (Pm_(2.5) ) on type 2 diabetes and the beneficial role of physical activity (PA), the influence of Pm_(2.5) on the relationship between PA and type 2 diabetes remains ***: In this prospective study with 71,689 participants, PA was assessed by a questionnaire and was categorized into quartiles for volume and three groups for intensity. Long-term Pm_(2.5) exposure was calculated using 1-km resolution satellite-based Pm_(2.5) estimates. Pm_(2.5) exposure and PA's effect on type 2 diabetes were assessed by cohort-stratified Cox proportional hazards models, individually and in ***: In 488,166 person-years of follow-up, 5487 incident type 2 diabetes cases were observed. The association between PA and type 2 diabetes was modified by Pm_(2.5) . Compared with the lowest quartile of PA volume, the highest quartile was associated with reduced type 2 diabetes risk in low Pm_(2.5) stratification (≤65.02 μg/m^(3)) other than in high Pm_(2.5) stratification (>65.02 μg/m^(3)), with the hazard ratio (HR) of 0.75 (95% confidence interval [CI]: 0.66-0.85) and 1.10 (95% CI: 0.99-1.22), respectively. Similar results were observed for PA intensity. High Pm_(2.5) exposure combined with the highest PA levels increased the risk of type 2 diabetes the most (HR= 1.79, 95% CI: 1.59-2.01 for PA volume;HR = 1.82, 95% CI: 1.64-2.02 for PA intensity).Conclusion: PA could reduce type 2 diabetes risk in low-pollution areas, but high Pm_(2.5) exposure may weaken or even reverse the protective effects of PA. Safety and health benefits of PA should be thoroughly assessed for long-term polluted residents.

关键词： fine particulate matter physical activity type 2 diabetes

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变系数的周期性时间序列模型及其应用

应用概率统计 2024年第1期40卷 50-74页

作者：方学莉王守霞上海财经大学统计与管理学院上海200433 北京大学数学科学学院北京100871

存在于各个领域的时间序列不仅表现出周期性的特征还易受外界因素的影响,而且外界因素的影响并非一成不变,同时,部分时间序列的周期是未知的.对于这样的易受外界因素影响的周期性时间序列,本文旨在构造含有变系数函数的周期性序列模型.... 详细信息

存在于各个领域的时间序列不仅表现出周期性的特征还易受外界因素的影响,而且外界因素的影响并非一成不变,同时,部分时间序列的周期是未知的.对于这样的易受外界因素影响的周期性时间序列,本文旨在构造含有变系数函数的周期性序列模型.将经典的时间序列模型分解成一个含有未知参数的部分线性变系数模型,利用B样条逼近外生变量的变系数函数,借助带有l_(0)惩罚项的最小二乘回归得到未知周期、周期序列以及外生变量的影响系数的估计结果.本文还给出了估计量的理论性质,包括周期估计的相合性、周期序列估计和变系数函数估计的渐近性质.通过第4章的模拟,我们展现了本文方法的优越性.最后我们通过三个实际数据的应用展现了本文方法的实用性.

关键词：周期估计 l_(0)惩罚 B样条变系数模型

景观格局因子交互作用对科尔沁沙地沙漠化的影响

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中国沙漠 2024年第2期44卷 99-108页

作者：蔡明玉贾飚常学礼烟台工程职业技术学院山东烟台264006 内蒙古自治区水利科学研究院内蒙古呼和浩特010051 鲁东大学资源与环境工程学院山东烟台264025

将景观生态学原理运用到沙漠化现状的准确和快捷评估是景观生态学研究面临的一个挑战。本文以2000年和2018年奈曼旗中部沙区土地利用类型数据为基础,选定最大斑块指数(LPI)、边界密度(ED)、聚集度指数(AI)和香农指数(SHDI),借助地理探... 详细信息

将景观生态学原理运用到沙漠化现状的准确和快捷评估是景观生态学研究面临的一个挑战。本文以2000年和2018年奈曼旗中部沙区土地利用类型数据为基础,选定最大斑块指数(LPI)、边界密度(ED)、聚集度指数(AI)和香农指数(SHDI),借助地理探测器模型和Fragstats软件中的moving window功能分析了景观格局双因子交互作用及因子分级对沙漠化现状的影响。结果表明:2000—2018年是研究区沙漠化逆转期,沙漠化现状指数由0.393减少到0.288。景观格局双因子交互作用有非线性增强和双因子增强两种形式且对沙漠化现状的影响大于各因子独立作用。不同格局因子分级对沙漠化现状影响存在差异,导致差异原因与不同沙丘类型面积和分布格局有关。在沙漠化现状较强年份(2000年),LPI和ED分级导致的沙漠化现状显著区,以流动沙丘占优势(30.6%~42.9%),不显著区以固定沙丘占优势(32.0%~44.0%)。在沙漠化现状较弱年份(2018年),SHDI分级导致的沙漠化现状显著区和不显著区都以流动沙丘占优势(均超过79.2%)。景观格局双因子交互对沙漠化现状影响既与时间有关,又与空间范围有关;交互作用对沙漠化现状的影响机制具有非线性特点;研究区范围大小直接影响到景观因子交互作用形式和空间格局(尺度依赖),任何典型案例研究结果不能跨尺度推绎,但方法可以统一。

关键词：地理探测器移动窗口法景观格局沙漠化现状科尔沁沙地

分步负载金属法制备铁钴双金属位点高效氧还原电催化剂

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化工学报 2024年第4期75卷 1578-1593页

作者：贾旭东杨博龙程前李雪丽向中华北京化工大学有机无机复合材料国家重点实验室北京100029

过渡金属和氮掺杂的碳(m-N-C)由于优异的电催化活性以及较低的生产成本,成为铂基催化剂的替代。然而,目前的m-N-C催化剂通常涉及金属盐、含氮物质和碳载体的结合,在经过热处理和酸洗过程后得到的催化剂在活性位点密度和传质能力上性能... 详细信息

过渡金属和氮掺杂的碳(m-N-C)由于优异的电催化活性以及较低的生产成本,成为铂基催化剂的替代。然而,目前的m-N-C催化剂通常涉及金属盐、含氮物质和碳载体的结合,在经过热处理和酸洗过程后得到的催化剂在活性位点密度和传质能力上性能不足。采用分步负载金属法制备了Fe、Co双金属掺杂的m-N-C催化剂。利用Zn2+和Co2+的竞争效应,成功合成了小尺寸且均匀的Zn-Co-ZIFs双金属沸石咪唑骨架。随后,在不形成金属团簇的前提下将最大量的Fe原子嵌入C-Zn-Co-ZIFs-H+前体结构中,使其在热解后能产生大量的FeCo—Nx活性位点。这种改进显著增加了FeCo-N-C-2催化剂中Fe活性位点的含量(1.9%,质量分数),并深度优化了其微孔和介孔结构(860 m^(2)·g^(-1))。该催化剂在0.1 mol·L^(-1) HClo_(4)和0.1 mol·L^(-1) KoH溶液中,氧还原反应(oRR)活性展现出了0.806 V和0.921 V的半波电位,并分别在50000、45000 s恒定电位测试后保持了91.21%和95.32%的活性。将其组装于质子交换膜燃料电池(PEmFCs)和碱性锌-空气液流电池(ZAFBs)中,峰值功率密度分别达到了746、164 mW·cm^(-2),显示出优越的性能。

关键词：催化剂分步负载金属法铁钴双金属位点电化学氧还原反应燃料电池锌-空气液流电池

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黄河中下游河水及沉积物花粉分布与传输特征

地理学报 2024年第5期79卷 1246-1264页

作者：刘德新潘燕芳何雪莉吴朋飞马建华谷蕾河南大学地理与环境学院开封475004 河南大学黄河中下游数字地理技术教育部重点实验室开封475004 河南大学黄河文明与可持续发展研究中心开封475001

厘清河流花粉现代过程是重建流域古环境的基础。尽管学界较早开展了河水花粉研究,但花粉进入河流之后如何传输、受何种动力影响等问题尚不清楚。本文选取黄河中下游干、支流布设采样断面,在丰水期采集河水和沉积物样品开展花粉分析,采... 详细信息

厘清河流花粉现代过程是重建流域古环境的基础。尽管学界较早开展了河水花粉研究,但花粉进入河流之后如何传输、受何种动力影响等问题尚不清楚。本文选取黄河中下游干、支流布设采样断面,在丰水期采集河水和沉积物样品开展花粉分析,采用地理探测器等研究方法,探究花粉分布特征及影响因素。结果表明:(1)不同流域植被组成不同,花粉类型百分比和浓度存在较大差异,河水干流花粉浓度大于支流,而沉积物花粉百分含量与浓度干流普遍低于支流。(2)悬浮物浓度是影响河水花粉含量的主要因素,且在晋陕峡谷之外的样点表现尤为突出;粗沙多、流速快可能是导致晋陕峡谷干流悬浮物浓度高而花粉浓度低的原因。(3)黏粒含量是影响沉积物花粉含量的主要因素,且黏粒分别和粉砂、流速交互作用的影响更为突出;黄河出晋陕峡谷后沉积物花粉含量明显增加。(4)水库前后河水和沉积物花粉浓度变化分别与悬浮物和黏粒一致,相较于水样,水库后沉积物花粉浓度减少更为明显。(5)河流花粉与表土花粉有良好的对应关系,能较好的反映流域整体植被面貌。研究结果可为利用冲积物或者有河流注入的湖泊花粉开展古环境重建提供支撑。

关键词：河水花粉沉积物花粉空间分布传输机制黄河中下游

The effect of hydrologic process changes on NDVI in the desert-oasis ecotone of the Hexi Corridor

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Science China Earth Sciences 2014年第12期57卷 3107-3117页

作者： ZHAo WenZhi CHANG xueli Linze Inland River Basin Research Station Key Laboratory of Ecohydrology of Inland River Basin Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences School of Geography and Planning Ludong University

In the arid inland river basins of northwestern China,human activities control almost all the surface hydrologic *** potential effects of these altered hydrologic processes are gradually becoming clear,especially since the 2000 implementation of the integrated water resources management projects in the Shiyang River,the Heihe River,the Tarim River,and the Shuler *** the appearance of these eco-hydrology changes and consequent environmental effects in the oasis has attracted broad attention,related research is still ***-hydrological process changes in the desert-oasis ecotone were investigated in the Pingchuan irrigation district in the middle reaches of the Heihe *** results showed that the annual average amount of surface water irrigation during the past 20 years has decreased by 1.498×107 m3,while the annual average amount of well irrigation has increased by 1.457×107 m3,since 2000,when the State Council of China approved the water diversion scheme for the Heihe River *** groundwater depth before the water diversion scheme generally varied between2.44–3.19 m(average 2.73±0.24 m),while that after the water diversion scheme has varied between 3.08–4.01 m(average3.79±0.62 m).The distribution area ofm groundwater depth decreased from 3612 to 394 hm2;while the distribution area of>3 m groundwater depth increased from 853 to 3843 ***,although the hydrologic processes changed dramatically,no significant effects on vegetation productivity in the desert-oasis ecotone were detected during the study period.

关键词： Hexi Corridor desert-oasis ecotone Pingchuan irrigation district hydrologic processes groundwater depth NDVI

PVP-assisted synthesis of porous Coo prisms with enhanced electrocatalytic oxygen evolution properties

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Journal of Energy Chemistry 2017年第6期26卷 1210-1216页

作者： xueli Zhao Wei Zhang Rui Cao School of Chemistry and Chemical Engineering Shaanxi Normal University Department of Chemistry Renmin University of China

Hollow metal oxide materials with nanometer-to-micrometer dimensions have attracted tremendous attention because of their potential applications in energy conversion and storage systems. Numerous efforts have been focused on developing versatile methods for the rational synthesis of various hollow structures to act as efficient water oxidation catalysts. In this work, a unique porous and hollow Coo tetragonal prism-like structure has been successfully synthesized via a facile and efficient co-precipitation method with polyvinylpyrrolidone（PVP K30） followed by a heating treatment of the resulted *** as-prepared porous and hollow Coo microprisms displayed a high activity and stability for water oxidation in 1.0 m KoH solution. To reach a current density of 10 m A/cm, a low overpotential of 280 m V is required. The remarkable activity can be attributed to the synergistic effect between two different but well-distributed Coo crystalline phases, uniform particle size, ameliorative crystallinity, high surface area and the low mass transfer resistance benefitted from the unique porous structure.

关键词： Cobalt oxide Electrocatalysis oxygen evolution Porous structure Water oxidation

Thermodynamic analysis of steam reforming of glycerol for hydrogen production at atmospheric pressure

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Frontiers of Chemical Science and Engineering 2021年第1期15卷 60-71页

作者： Ammaru Ismaila xueli Chen Xin Gao Xiaolei Fan Department of Chemical Engineering and Analytical Science School of EngineeringThe University of ManchesterManchester M139PLUK Institute of Clean Coal Technology East China University of Science and TechnologyShanghai 200237China School of Chemical Engineering and Technology National Engineering Research Center of Distillation TechnologyCollaborative Innovation Center of Chemical Science and Engineering(Tianjin)Tianjin UniversityTianjin 300072China

Thermodynamic chemical equilibrium analysis of steam reforming of glycerol(SRG)for selective hydrogen production was performed based on the Gibbs free energy minimisation *** ideal SRG reaction(C_(3)H_(8)o_(3)+3H_(2)o→3Co_(2)+7H_(2))and a comprehensive set of side reactions during SRG are considered for the formation of a wide range of ***,this work focused on the analysis of formation of H_(2),Co_(2),Co and CH4 in the gas phase and determination of the carbon free region in SRG under the conditions at atmospheric pressure,600 K–1100 K and 1.013×10^(5)–1.013×10^(6) Pa with the steam-to-glycerol feed ratios(SGFR)of 1:5–*** reaction conditions which favoured SRG for H_(2) production with minimum coke formation were identifies as:atmospheric pressure,temperatures of 900 K–1050 K and SGFR of 10:*** influence of using the inert carrier gas(i.e.,N_(2))in SRG was studied as well at atmospheric *** the presence of N_(2) in the stream decreased the partial pressure of reactants,it was beneficial to improve the equilibrium yield of H_(2).Under both conditions of SRG(with/without inert gas),the CH4 production is minimised,and carbon formation was thermodynamically unfavoured at steam rich conditions of SGFR>5:1.

关键词： steam reforming of glycerol H_(2) N_(2) carbon deposition thermodynamic analysis Gibbs free energy minimisation