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Journal of Thermal Science 2024年第1期33卷 101-113页

作者： YUAN Baoqiang WANG wei xin Gongming DU Wenjing School of Energy and Power Engineering Shandong UniversityJi'nan 250061China

Large eddy simulations have been conducted to study upward transitional flows and heat transfer characteristics of supercritical CO_(2) in a vertical *** numerical simulation was carried out on a modified buoyantPimpleFOAM solver in OpenFOAM 7,and was verified using experiment *** results indicate that increasing the Grashof numbers can reduce the flow stability and make the flow transition *** are four stages of heat transfer in the transition process,i.e.,weakened,improved,recovered and normal heat *** heat transfer phenomena in the transition process were explained from three perspectives:thermal boundary layer theory,turbulent transport and pseudo-boiling *** transfer enhancement during transition is related to the transport of supercritical molecular clusters,and these molecular clusters are regarded as pseudo-bubbles in pseudo-boiling *** flow pattern of the pseudo-phases in the dia-Widom process contains single-phase flow,steady pseudo-film flow,unsteady pseudo-film flow,partial pseudo-bubbles flow and flocculent pseudo-film ***-bubbles have similar behaviors to subcritical bubbles,i.e.,break-up,deformation,condensation and *** researches in this work are favorable for understanding the heat transfer mechanism of supercritical fluids during flow transition.

关键词： supercritical heat transfer large eddy simulation transition pseudo-boiling

公共服务供给对流动人口的“挤出效应”与“选择效应”——基于2017年全国流动人口动态监测数据的分析

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人口与发展 2022年第4期28卷 15-27页

作者：魏新月交通运输部科学研究院北京100029

基于2017年全国流动人口动态监测数据,分析了公共服务供给、房价收入比和流动人口居留意愿三者之间的关系。研究结果表明:第一,公共服务供给不仅直接强化了流动人口的居留意愿,而且通过房价收入比间接影响流动人口的居留意愿,综合考虑... 详细信息

基于2017年全国流动人口动态监测数据,分析了公共服务供给、房价收入比和流动人口居留意愿三者之间的关系。研究结果表明:第一,公共服务供给不仅直接强化了流动人口的居留意愿,而且通过房价收入比间接影响流动人口的居留意愿,综合考虑变量不同表示方法与样本选择后,结果仍保持稳健;第二,对于不同行政等级的城市,中心城市的房价收入比在公共服务供给强化居留意愿过程中的中介作用要小于非中心城市房价收入比的中介作用;第三,公共服务供给通过房价选择了高收入的流动人口留下,同时挤出了无法承担高生活成本的低收入流动人口,解释了为什么公共服务供给降低了流动人口的房价收入比,进而增加其居留意愿。

关键词：公共服务供给房价收入比居留意愿挤出效应选择效应

Flow Field Simulation and Parameter Analysis of Hydraulic Unbalanced Bionic Self-recovery Actuator for Rotary Equipment

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Journal of Bionic Engineering 2024年第1期21卷 325-343页

作者： wei Li xin Pan Dehong Ge Jinji Gao Key Laboratory of Engine Health Monitoring-Control and Networking of Ministry of Education Beijing University of Chemical TechnologyBeijing 100029China Beijing Key Laboratory of High-End Mechanical Equipment Health Monitoring and Self-Recovery Beijing University of Chemical TechnologyBeijing 100029China

The rotor is the most important component of rotating machinery,and the vibration produced by its mass unbalance has a serious influence on the secure and steady operation of the machine,so an effective online suppression technology is urgently needed.A new hydraulic unbalanced bionic self-recovery system is introduced,imitating the way of manually repairing faulty *** accomplish the effect of actuator mass redistribution,the technology employs pressurized air to drive the quantitative transfer of liquid in the reservoir cavity at opposite *** can complete the online adjustment of the equipment's balancing state and suppress the unbalanced vibration of equipment in real time,which gives the equipment the ability to maintain an autonomous health state and improve equipment *** composition and working principle of the system are introduced in detail,and the key performance parameters,such as the minimum running speed and the balancing liquid transfer speed,are analyzed *** fluid-solid coupling model of the actuator was established,and the two-phase flow from inside the hydraulic unbalanced bionic self-recovery actuator was simulated under multiple working conditions and the performance parameters were quantitatively analyzed.A balancing simulation test bed was built,and its effectiveness was verified by performance parameter tests and unbalanced bionic self-recovery *** experimental results show that the mass distribution adjustment of the balancing disk can be achieved using different viscosity balancing liquid,and the response of liquid viscosity 10 cSt is faster than that of liquid viscosity 100 cSt in the process of balancing liquid transfer,and the time is reduced by more than 75%;the system can reduce the simulated rotor amplitude from 18.3μm to 10.6μm online in real time,which provides technical support for the subsequent development of a new generation of bionic intelligent equipment.

关键词： Engineering self-recovery-Bionics Simulation analysis Self-recovery regulation

Determination of the chromosomal position effects for plug-and-play application in the Myxococcus xanthus chassis cells

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Synthetic and Systems Biotechnology 2024年第3期9卷 540-548页

作者： xin-jing yue Jia-rui Wang Jun-ning Zhao Zhuo Pan yue-zhong Li State Key Laboratory of Microbial Technology Institute of Microbial TechnologyShandong UniversityQingdaoPR China

The chromosomal position effect can significantly affect the transgene expression,which may provide an efficient strategy for the inauguration of alien genes in new hosts,but has been less explored *** bacterium Myxococcus xanthus harbors a large circular high-GC genome,and the position effect in this chassis may result in a thousand-fold expression variation of alien natural *** this study,we conducted transposon insertion at TA sites on the *** genome,and used enrichment and dilution indexes to respectively appraise high and low expression potentials of alien genes at insertion *** enrichment sites are characteristically distributed along the genome,and the dilution sites are overlapped well with the horizontal transfer *** experimentally demonstrated the enrichment sites as high expression integration sites(HEISs),and the dilution sites unsuitable for gene integration *** work highlights that HEISs are the plug-and-play sites for efficient expression of integrated genes.

关键词： Position effect High expression integration sites(HEISs) Myxococcus xanthus Tn-seq

Regulating the oxidation state of Pd to enhance the selective hydrogenation for 5-hydroxymethylfurfural

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Chinese Journal of Chemical Engineering 2024年第8期72卷 60-68页

作者： xin Li yue Ma Xuning Wang Jianguo Wu Dong Cao Daojian Cheng State Key Laboratory of Organic-Inorganic Composites and College of Chemical Engineering Beijing University of Chemical TechnologyBeijing 100029China

The highly selective hydrogenation of 5-hydroxymethylfurfural to 2,5-dihydroxymethylfuran is an important reaction in the field of biomass hydrogenation,because it is a bridge between biomass resources and chemical ***,we precisely constructed carbon nitride supported Pd-based catalysts by a simple impregnation-reduction *** changing the reduction temperature,catalysts with different oxidation state could be precisely ***,the important correlation between the ratio of Pd^(0)/Pd^(2+)and catalytic activity is revealed during the selective hydrogenation of *** Pd/g—C_(3)N_(4)—300 catalyst with a Pd^(0)/Pd^(2+)ratio of 3/2 showed the highest catalytic activity,which could get 96.9%5-hydroxymethylfurfural conversion and 90.3%2,5-dihydroxymethylfuran *** density functional theory calculation revealed that the synergistic effect between Pd0and Pd2+in Pd/g—C_(3)N_(4)—300 system could boost the adsorption of the substrate and the dissociation of *** this work,we highlight the important correlation between metal oxidation state and catalytic activity,which provides valuable insights for the rational design of precious metal catalysts for hydrogenation reactions.

关键词： Pd/g-C_(3)N_(4) Selective hydrogenation 5-hydroxymethylfurfural 2,5-dihydroxymethylfuran Oxidation state

Natural products inspired[3+2]cycloaddition enables efficient construction of hydroxylated tetrahydrofuran acetals and concise syntheses of lignans

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Science China Chemistry 2024年第7期67卷 2306-2313页

作者： Dong-yue Cai weiming Shi Zhao-Hui Jin Zhi-Xiang Yu Jin-xin Zhao Jian-Min yue State Key Laboratory of Drug Research Shanghai Institute of Materia MedicaChinese Academy of SciencesShanghai 201203China University of Chinese Academy of Sciences Beijing 100049China Beijing National Laboratory for Molecular Sciences(BNLMS) Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of EducationCollege of ChemistryPeking UniversityBeijing 100871China

Mimicking biosynthetic pathways of hongkonoids led to the development of a new Cu(Ⅰ)-catalyzed[3+2]cycloaddition ofα-hydroxyketone andβ-keto enol ethers,affording tetrahydrofuran acetals in a highly diastereoselective manner and 100%atom *** studies on the mechanism disclosed a concerted but asynchronous Michael addition/aldol *** the same importance,this methodology provides a practical biomimetic approach for one-step construction of the dibenzylbutyrolactol lignan backbone starting from two phenyl propane derivatives,opening up a powerful new approach for lignan synthesis,which is showcased by succinct total syntheses of two biologically important aryltetralin-type lignans,β-apopicropodophyllin and *** the mild and operationally simple conditions,the developed chemistry might have a promising prospect in potential industrial applications.

关键词： [3+2]cycloaddition transition-metal catalysis tetrahydrofuran lignans natural products

Water as dispersion medium to fabricate homogeneous nanohectorite solid-state electrolyte for suppressing lithium dendrite

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Journal of Materiomics 2024年第2期10卷 463-470页

作者： xin Pei Wenfei wei Gang He xinjiang Institute of Technology Xinjiang843100China Engineering Research Center of Nano-Geomaterials of Ministry of Education Faculty of Materials Science and ChemistryChina University of GeosciencesWuhan430074China Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources Qinghai Institute of Salt LakesChinese Academy of SciencesXiningQinghai810008China

The rational design of green chemical,low-cost,and highly efficient solid-state electrolytes for Li-metal anode is a promising but still challenging strategy for preventing Li dendrite growth and developing safe and ultralong cycle life Li-metal ***,a homogeneous composite solid polymer electrolyte(CSPE)is fabricated with water as the ideal dispersion medium,hectorite(Ht)as nanofiller,and poly(ethylene oxide)(PEO)as the matrix,to guide uniform Li plating/*** from the merit of Ht can form uniformly dispersed nanosheets in water,the obtained CSPE inheres to a low melting point,robust mechanical property,and high Li^(+)transference ***,the fabricated Li symmetric battery using PEO-Ht-LiClO_(4)CSPE keeps cycling steadily for 4000 *** well demonstrated water-based CSPE paves the way for developing low-cost,environmentally friendly,and safe solid-state electrolytes for Li-metal batteries.

关键词： Water Solid-state electrolytes Homogeneous Hectorite Li-metal battery

Natural marmatite photocatalyst for treatment of mineral processing wastewater to help zero wastewater discharge

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Journal of Environmental Sciences 2024年第8期142卷 83-91页

作者： Meirong Wu wei Sun Xiangsong Meng Jianhua Kang yue Yang School of Minerals Processing and Bioengineering Central South UniversityChangsha 410083China Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources Central South UniversityChangsha 410083China

Mineral processing wastewater(MPW)with large discharge and high toxicity affects environmental safety,and the realizing zero discharge of MPW is of great significance for reducing environmental pollution,saving water resources,and promoting the sustainable development of the mining *** this study,we reported natural marmatite(NM)as a low-cost and efficient photocatalyst for the treatment of MPW to help zero wastewater *** photocatalytic activity of NM was evaluated by the removal of total organic carbon(TOC)from MPW under visible-light illumination,and the optimal degradation conditions were *** showed that superoxide free radicals(^(·)O_(2)^(-))were the dominant active species responsible for organic pollutants degradation,and 74.25%TOC removal was obtained after 120 min reaction under the optimum treatment ***,the wastewater treated by NM photocatalysis can be reused in the flotation system without adverse impact on the product *** on these findings,a model of zero wastewater discharge for flotation with the help of photocatalytic treatment was established,it indicated that the water of the whole system can be balanced without affecting the ore dressing index,which showed that visible light-driven photocatalyst has a promising application prospect in the treatment and recycling of industrial wastewater.

关键词： Natural mineral Photocatalysis Industrial wastewater Wastewater recycling Water balance

Numerical simulation of transient characteristics in a bulb turbine during the load rejection process

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Journal of Hydrodynamics 2024年第1期36卷 170-183页

作者： yue Lu Yu-quan Zhang Zhong-wei He Yuan Zheng College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing210098China College of Energy and Electrical Engineering Hohai UniversityNanjing210098China Huadong Engineering Corporation Ltd. Hangzhou311122China

To evaluate the safety of the bulb tubular turbine,the dynamic hydraulic characteristics of a hydropower station system during the load rejection process are studied through numerical simulations and a prototype *** the developed model,a dynamic grid technology(DGT)controls the closure of the guide vane and the blade,whilst the moment balance equation and the user-defined function(UDF)provide the runner’s rotation *** 3-D transient simulation method can well predict the rotation speed and mass flow curves in the state of load *** simulation outcomes of the system performance are basically consistent with the measurement data of the *** observed,the runner is subjected to the reversely increased torque and axial force,the system is in a braking phase,and the maximum speed peaks at 144.6%of the rated ***,the internal flow of the runner is greatly affected by the closure of the guide vane,and the draft tube forms an eccentric spiral vortex *** breaks downstream,aggravating the instability of the draft ***,the transient characteristics span for the first five seconds,demonstrating the importance of establishing an efficient governing *** obtained results are useful for designing the turbine’s flow channel with a double regulating function and comprehending the turbine’s transient characteristics.

关键词： Bulb tubular turbine load rejection numerical simulation dynamic grid prototype test

High-throughput microfluidic production of carbon capture microcapsules:fundamentals,applications,and perspectives

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International Journal of Extreme Manufacturing 2024年第3期6卷 330-361页

作者： Xiangdong Liu wei Gao yue Lu Liangyu Wu Yongping Chen College of Electrical Energy and Power EngineeringYangzhou UniversityYangzhouJiangsu 225127People’s Republic of China Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjingJiangsu 210096People’s Republic of China Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application School of Environmental Science and EngineeringSuzhou University of Science and TechnologySuzhouJiangsu 215009People’s Republic of China

In the last three decades,carbon dioxide(CO_(2)) emissions have shown a significant increase from various *** address this pressing issue,the importance of reducing CO_(2) emissions has grown,leading to increased attention toward carbon capture,utilization,and storage *** these strategies,monodisperse microcapsules,produced by using droplet microfluidics,have emerged as promising tools for carbon capture,offering a potential solution to mitigate CO_(2) ***,the limited yield of microcapsules due to the inherent low flow rate in droplet microfluidics remains a *** this comprehensive review,the high-throughput production of carbon capture microcapsules using droplet microfluidics is focused ***,the detailed insights into microfluidic chip fabrication technologies,the microfluidic generation of emulsion droplets,along with the associated hydrodynamic considerations,and the generation of carbon capture microcapsules through droplet microfluidics are *** review highlights the substantial potential of droplet microfluidics as a promising technique for large-scale carbon capture microcapsule production,which could play a significant role in achieving carbon neutralization and emission reduction goals.

关键词： carbon capture microcapsules droplet microfluidic high-throughput production carbon neutralization