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High efficient catalytic oxidation of 5-hydroxymethylfurfural into 2,5-furandicarboxylic acid under benign conditions with nitrogen-doped graphene encapsulated Cu nanoparticles

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Journal of Energy Chemistry 2020年第11期29卷 96-105页

作者： Chaoxin Yang Xiao li Zhenzhou Zhang Bohan Lv jiachun li Zhenjian liu Wanzhen Zhu Furong Tao Guangqiang Lv Yongxing Yang Shandong Provincial Key Laboratory of Molecular Engineering Qilu University of Technology(Shandong Academy of Sciences)Jinan 250353ShandongChina Key Laboratory of Coal Processing and Efficient Utilization Ministry of EducationChina University of Mining and TechnologyXuzhou 221116JiangsuChina Engineering Research Center of Advanced Functional Material Manufacturing of Ministry of Education School of Chemical EngineeringZhengzhou University.Zhengzhou 450001HenanChina School of Chemistry and Chemical Engineering Shanxi UniversityTaiyuan 030006ShanxiChina

Selective oxidation of 5-hydroxymethylfurfual(HMF) to 2,5-furandicarboxylic acid(FDCA) as a bioplastics monomer is efficiently promoted by a simple system without noble-metal and base additives. In this work, graphene oxide(GO) was first synthesised by an electrochemical method with flexible graphite paper(FGP) as start carbon material, then, nitrogen-doped graphene(NG) layers encapsulated Cu nanoparticles(NPs) was prepared by one-step thermal treatment of GO supported Cu2+ in flowing NH3 atmosphere. Compared with NG supported Cu NPs prepared by the traditional impregnation method, enhanced catalytic activity was achieved over Cu/NG and an FDCA yield of 95.2% was achieved under mild reaction conditions with tert-butylhydroperoxide(t-BuOOH) as the oxidant. Control experiments with different catalysts and different addition procedure of t-BuOOH showed the yield of HMF and various intermediates during reaction. From the changing of intermediates concentrations and reaction rates, a reaction pathway through HMF-DFF-FFCA-FDCA was proposed. This work gives a more convenient, more green,more economical and effective method in encapsulated metal NPs preparation and high selectivity in HMF oxidation to FDCA under mild conditions.

关键词： Graphene oxide Encapsulated nanoparticles 5-hydroxymethylfurfual 2,5-furandicarboxylic acid Oxidation Noble-metal free

Periodic signal extraction of GNSS height time series based on adaptive singular spectrum analysis

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Geodesy and Geodynamics 2024年第1期15卷 50-60页

作者： Chenfeng li Peibing Yang Tengxu Zhang jiachun Guo Three Gorges Geotechnical Engineering Co.Ltd.(Wuhan) Wuhan 430074China College of Resources and Environmental Science and Engineering Hubei University of Science and TechnologyXian©ning 437100China College of Civil Engineering Anhui Jianzhu UniversityHefei 230601China

Singular spectrum analysis is widely used in geodetic time series ***,when extracting time-varying periodic signals from a large number of Global Navigation Satellite System(GNSS)time series,the selection of appropriate embedding window size and principal components makes this method cumbersome and *** improve the efficiency and accuracy of singular spectrum analysis,this paper proposes an adaptive singular spectrum analysis method by combining spectrum analysis with a new trace *** running time and correlation analysis indicate that the proposed method can adaptively set the embedding window size to extract the time-varying periodic signals from GNSS time series,and the extraction efficiency of a single time series is six times that of singular spectrum *** method is also accurate and more suitable for time-varying periodic signal analysis of global GNSS sites.

关键词： GNSS Time series Singular spectrum analysis Trace matrix Periodic signal

Workshop结合同伴教学的教学模式对肌骨超声教学的效果分析

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中国毕业后医学教育 2024年第9期8卷 695-697,702页

作者：刘文芬李家春林惠通李任杰徐作峰中山大学附属第七医院(深圳)超声科广东深圳518107 中山大学附属第七医院(深圳)骨科广东深圳518107

目的探讨工作坊(workshop)结合同伴教学的教学模式与传统教学模式在肌骨超声教学效果的差异。方法选取2018年11月—2023年10月先后在中山大学附属第七医院超声科学习的住院医师、进修生、实习生共60名,随机分为观察组和对照组,每组人数3... 详细信息

目的探讨工作坊(workshop)结合同伴教学的教学模式与传统教学模式在肌骨超声教学效果的差异。方法选取2018年11月—2023年10月先后在中山大学附属第七医院超声科学习的住院医师、进修生、实习生共60名,随机分为观察组和对照组,每组人数30名。观察组采用workshop结合同伴教学法,对照组采用传统教学法。两组学员在入科前均不具备肌骨超声相关理论知识及实践操作经验。学习期满对两组学员均采用理论考核、上机操作的考核方式,并收集学员的满意度问卷调查表,比较两种教学方法的效果。结果观察组的理论考核、上机操作成绩及问卷调查满意度均高于对照组,差异有统计学意义(P<0.05)。结论workshop结合同伴教学的教学模式可促进学员更好地掌握肌骨超声的理论知识及实践操作能力,明显提高了肌骨超声教学效果,学员对该学习方式感到满意。

关键词： workshop教学法同伴教学肌肉骨骼超声住院医师规范化培训

Strength softening models of soil and its application in rainfall-induced landslide simulation

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Theoretical & Applied Mechanics Letters 2013年第4期3卷 23-28页

作者： Zhendong Fu jiachun li Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of Mechanics Chinese Academy of Sciences

In this study, strength softening models are developed for exploring rainfall-induced landslide mechanism based on Mohr Coulomb strength theory with both saturation degree and temporal evolution into consideration. According to the ratio of two time scales available, the model can be classified into three categories, i.e., instant softening model, delay softening model, and coupling softening model. Corresponding evolution functions are specified to represent these kinds of softening processes and then applied to simulate landslide of homogeneous slopes triggered by rainfall, therefrom, useful conclusions can be drawn in the end.

关键词： homogeneous slope numerical simulation strength softening model rainfall-induced landslide geological disaster

2017—2021年我国先天性心脏病外科手术开展情况调查

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中华医学杂志 2024年第18期104卷 1617-1622页

作者：江春景黑飞龙龙村朱德明李欣刘斌章晓华王伟刘燕金振晓李佳春武婷王红郝星侯晓彤首都医科大学附属北京安贞医院体外循环及机械循环辅助科北京中国医学科学院北京协和医学院阜外医院体外循环中心北京上海交通大学医学院附属上海儿童医学中心上海复旦大学附属中山医院心血管外科上海四川大学华西医院麻醉科成都广东省人民医院心外科体外循环室广州武汉亚洲心脏病医院体外循环科武汉空军军医大学西京医院心血管外科西安解放军总医院第一医学中心心血管外科北京天津市胸科医院心血管外科天津首都医科大学附属北京安贞医院心脏外科危重症中心北京

目的调查2017—2021年我国先天性心脏病(CHD)外科手术开展情况。方法该研究为现况调查。基于中国生物医学工程学会体外循环分会收集整理的2017—2021年我国31个省(自治区、直辖市)CHD外科手术数据资料, 总结各省/区域、综合/专科医院、... 详细信息

目的调查2017—2021年我国先天性心脏病(CHD)外科手术开展情况。方法该研究为现况调查。基于中国生物医学工程学会体外循环分会收集整理的2017—2021年我国31个省(自治区、直辖市)CHD外科手术数据资料, 总结各省/区域、综合/专科医院、不同年龄(是否≤18岁)的CHD外科手术开展情况, 并分析各省/区域的开展例数与地区生产总值、地区人口数量之间的相关性。结果 2017—2021年, 我国31个省(自治区、直辖市)CHD心血管外科年手术量依次为77 120、77 634、81 161、62 663及71 492例, 总体呈下降趋势;≤18岁的CHD外科手术占比也呈下降趋势, 从2017年的79.8%(61 557/77 120)降至2021年的58.6%(41 871/71 492)(P=0.027);各省份之间的手术例数差别较大, 其中≥5 000例有4个省份, 2 000～5 000例有9个省份;5年期间, 华中及华东地区的CHD外科手术例数最多, 占总例数的41.1%～45.5%。≤18岁CHD手术例数占比最高的为西南地区(69.7%～87.4%), 占比较低的为东北地区(28.2%～68.9%)。除2021年外, 2017—2020年各区域开展例数与其当年的地区生产总值(r值分别为0.929、0.929、0.893、0.964, 均P<0.05)及人口数量(r值分别为0.821、0.893、0.821、0.857, 均P<0.05)呈高度正相关;5年期间, 年开展例数在100例以上(医院数量占比为20.5%±1.2%)的医院完成了86.2%±1.2%的手术量。2017及2021年儿童/妇幼专科医院开展CHD外科手术例数分别占总例数的24.3%(18 772/77 120)及23.8%(17 012/71 492)。结论 2017—2021年, 我国CHD外科手术例数略有下降, 其中成人CHD患者手术占比增高。各地区开展CHD手术例数与当地经济发展状况的相关性较强。儿童/妇幼医院年开展CHD外科手术例数约占全国总例数的1/4。

关键词：心血管外科手术先天性心脏病手术量

Degradation properties of fulvic acid and its microbially driven mechanism from a partial nitritation bioreactor through multi-spectral and bioinformatic analysis

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Journal of Environmental Sciences 2024年第1期135卷 318-331页

作者： Quanhao Dou li Zhang Tingjun Dong Zixuan Song Xuepeng Fan Yongzhen Peng Xiayan Wang jiachun Yang National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery EngineeringBeijing University of TechnologyBeijing 100124China Department of Chemistry and Biology Center of Excellence for Environmental Safety and Biological EffectsBeijing Key Laboratory for Green Catalysis and SeparationBeijing University of TechnologyBeijing 100124China Environmental Protection Development Group Co. Ltd.Shandong 250101China

This study employed multispectral techniques to evaluate fulvic acid(FA)compositional characteristic and elucidate its biodegradation mechanisms during partial nitritation(PN)*** showed that FA removal efficiency(FRE)decreased from 90.22 to 23.11%when FA concentrations in the reactor were increased from 0 to 162.30 mg/L,and that molecular size,degree of aromatization and humification of the effluent FA macromolecules all increased after *** population analysis indicated that the proliferation of the Comamonas,OLB12 and Thauera exhibit high FA utilization capacity in lower concentrations(lism-related pathways,thereby impeding FA removal and total nitrogen loss associated with N_(2)O emissions.

关键词： Partial nitritation Fulvic acid 3DEEM-PARAFAC UV/Vis Microbially driven mechanism

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Foreword

Theoretical & Applied Mechanics Letters 2011年第1期1卷 3-4页

作者： Editors-in-Chief: jiachun li and Yonggang Huang

The inauguration issue of Theoretical and Applied Mechanics Letter (TAML) finally appears at the beginning of 2011,after more than one year of planning and *** letter-type journal aims at rapid publication of mechanics-related *** few mechanics journals publish letter-type *** is the first mechanics journal to devote completely to letter-type articles such that new ideas,discoveries

关键词： TAML Foreword

Estimation of extreme wind speed in SCS and NWP by a non-stationary model

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Theoretical & Applied Mechanics Letters 2016年第3期6卷 131-138页

作者： lizhen Wang jiachun li Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of Mechanics Chinese Academy of Sciences

In offshore engineering design, it is considerably significant to have an adequately accurate estimation of marine environmental parameters, in particular, the extreme wind speed of tropical cyclone （TC） with different return periods to guarantee the safety in projected operating life period. Based on the 71-year （1945-2015） TC data in the Northwest Pacific （NWP） by the Joint Typhoon Warning Center （JTWC） of US, a notable growth of the TC intensity is observed in the context of climate change. The fact implies that the traditional stationary model might be incapable of predicting parameters in the extreme events. Therefore, a non-stationary model is proposed in this study to estimate extreme wind speed in the South China Sea （SCS） and NWP. We find that the extreme wind speeds of different return periods exhibit an evident enhancement trend, for instance, the extreme wind speeds with different return periods by non- stationary model are 4.1%-4.4% higher than stationary ones in SCS. Also, the spatial distribution of extreme wind speed in NWP has been examined with the same methodology by dividing the west sea areas of the NWP 0°-45°N, 105°E-130°E into 45 subareas of 5° × 5°, where oil and gas resources are abundant. Similarly, remarkable spacial in-homogeneity in the extreme wind speed is seen in this area： the extreme wind speed with 50-year return period in the subarea （15°N-20°N, 115°E-120°E） of Zhongsha and Dongsha Islands is 73.8 m/s, while that in the subarea of Yellow Sea （30°N-35°N, 120°E-125°E） is only 47.1 m/s. As a result, the present study demonstrates that non-stationary and in-homogeneous effects should be taken into consideration in the estimation of extreme wind speed.

关键词： Tropical cyclone Non-stationary process Extreme wind speed Return period The Northwest Pacific The South China Sea

高频脉冲管制冷机的蓄冷器源汇模型、流动模拟和参数优化

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力学学报 2017年第2期49卷 421-430页

作者：张珍李家春中国科学院力学研究所流固耦合系统力学重点实验室北京100190 中国科学院大学工程科学学院北京100049

蓄冷器是脉冲管制冷机的一个关键部件,其工作性能将直接影响整机性能.针对工质在蓄冷器内交变流动的特性,提出了一个新的源/汇项模型来模拟蓄冷器内的流动与换热,同时模型也考虑了气固间的非热平衡.对于蓄冷器和换热器内的固体填料,在... 详细信息

蓄冷器是脉冲管制冷机的一个关键部件,其工作性能将直接影响整机性能.针对工质在蓄冷器内交变流动的特性,提出了一个新的源/汇项模型来模拟蓄冷器内的流动与换热,同时模型也考虑了气固间的非热平衡.对于蓄冷器和换热器内的固体填料,在一些假定条件的基础上推导得到了固体物质的温度分布的解析解.该模型不需要建立固体的能量方程,减小了计算的工作量,避免了达西定律在高频下不适用的限制条件,并针对交变流动情况下对流换热系数的取值提出了解决方法.新模型的计算结果与实验结果符合良好,验证了模型的可靠性.进一步应用此模型分析了蓄冷器内部的热交换和制冷机理,并进行了蓄冷器的优化设计,对于不同目数,不同丝径,不同材料的丝网,进行了各种情况下蓄冷器的换热性能优化分析.

关键词：脉冲管制冷机蓄冷器源/汇项模型对流换热系数相位角