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Chemodiversity of soil dissolved organic matter affected by contrasting microplastics from different types of polymers

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Frontiers of Environmental Science & Engineering 2023年第12期17卷 149-162页

作者： Hong Yu Beidou Xi Lingling Shi Wenbing Tan State Key Laboratory of Environmental Criteria and Risk Assessment and State Environmental Protection Key Laboratory of Simulation and Control of Groundwater PollutionChinese Research Academy of Environmental SciencesBeijing 100012China

Chemodiversity of dissolved organic matter(DOM)is a crucial factor controlling soil nutrient availability,greenhouse gas emissions,and pollutant ***(MPs)are widespread pollutants in terrestrial ecosystems in many ***,the effects of MPs on DOM chemodiversity are not sufficiently understood,particularly under different types of *** UV-Vis spectroscopy,3D fluorescence spectroscopy,and Fourier-transform ion cyclotron resonance mass spectrometry,the effects of three prevalent MPs[polyethylene,polystyrene,and polyvinyl chloride(PVC)]on the chemical properties and composition of soil DOM were investigated via a 310-d soil incubation *** results showed that MPs reduced the aromatic and hydrophobic soil DOM components by more than 20%,with PVC MPs having the greatest ***,as MP contents increase,the humification level of soil DOM significantly *** increased DOM molecules with no heteroatom by 8.3%-14.0%,but decreased DOM molecules with nitrogen content by 17.0%-47.8%.This may be because MPs cause positive“priming effect,”resulting in the breakdown of bioavailable components in soil *** is also related to MPs changing microbial richness and diversity and enriching microbial communities involved in lignin compositions *** the presence of MPs,soil DOM chemodiversity depended on soil pH,electrical conductivity,dissolved organic carbon,soil organic matter,bacterial Shannon,and fungal Chao ***,DOM in MP-contaminated soils featured more lipids and less condensed aromatics and proteins/amino sugars,thereby conferring a lower DOM aromaticity and higher lability.

关键词： Microplastics Dissolved organic matter FT-ICR MS Chemodiversity Molecular signature

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Fabrication of MnO2 coating on aluminum honeycomb for fast catalytic decomposition of ozone at room temperature

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Journal of Environmental Sciences 2023年第12期134卷 34-43页

作者： Yunjuan He Pengyi Zhang Jie Yang Shan Wang Jinge Li State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China Beijing Key Laboratory for Indoor Air Quality Evaluation and Control Beijing 100084China

Herein, the coating of MnO2nanomaterials on the surface of aluminum honeycomb was carried out to meet the requirements of high air velocity, low pressure drop and high activity in ozone removal scenarios. A commercially readily available waterborne silica sol mixed with waterborne acrylate latex was creatively utilized as the binder. A series of coating samples were prepared by spray coating method and evaluated focusing on their adhesion strength and catalytic activity towards ozone decomposition in an air duct at room temperature, by varying MnO2/binder mass ratio and number of sprayings. It was found that the adhesion strength of the catalytic coatings on the aluminum honeycomb increased with the increase of binder mass ratio, but the increased binder made the catalyst particles closely packed,resulting in reduced exposure of active sites and decrease of ozone conversion. Accordingly,catalyst slurry with 81.8 wt.% MnO2in dry coating and spraying times of two were determined as the optimal process parameters. As-prepared aluminum honeycomb filter with MnO2layer of 50 μm thickness achieved ozone conversion of 29.3%±1.7% under conditions of air velocity 3.0 m/sec, relative humidity50%, room temperature(26°C) and initial ozone concentration of 200 ppbV. This filter can be well adaptable to indoor air purification equipment operating at high air velocity with low wind resistance.

关键词： Manganese dioxide Waterborne binder Coating Ozone conversion Catalyst

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Application of Omega vortex identification method in cavity buffeting noise

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Journal of Hydrodynamics 2021年第2期33卷 259-270页

作者： Yang-hui Zhang Xing-jun Hu Wei Lan Yi-chen Liu Mo Wang Jing-yu Wang State Key Laboratory of Automobile Simulation and Control Jilin UniversityChangchun 130025China

The cavity buffeting noise is related to the free shear layer oscillation and the periodic vortex shedding,where weak vortices coexist with strong vortices and the strong shear phenomenon also exists at the opening of the ***,it is of great significance to accurately capture vortices at the opening for the control of the cavity buffeting *** paper first compares the Omega vortex identification method with the Q andλ2criteria based on the large eddy simulation(LES)of the backward-facing step flow,and it is found that the Omega method enjoys the following advantages:it is not sensitive to a moderate threshold change andΩ=0.52 can be used as a fixed threshold,it can capture both the strong and weak vortices at the same time;and it will not be contaminated by the *** the Omega(Ω)method is applied to the LES of the cavity buffeting noise:the mechanism of the cavity buffeting noise is studied based on a simple cavity model firstly,and then the effects of the incoming boundary layer thicknesses and the incoming boundary layer shapes on the cavity buffeting noise are *** results show that:theΩmethod clearly captures the processes of the vortex generation,development,collision and fragmentation,verifying that the generation of the cavity buffeting noise is related to the free shear layer oscillation and the periodic vortex shedding;as the thickness of the incoming boundary layer increases,the free shear layer becomes more stable and the Helmholtz resonance is avoided effectively,thereby the cavity buffeting noise is reduced effectively,adding a convexity upstream of the cavity opening to interfere the shape of the incoming boundary layer to reduce the acoustic feedback effect can reduce the cavity buffeting noise effectively.

关键词： Vortex identification Omega(Ω) buffeting noise boundary layer

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simulation Research on Dynamic Characteristics of Hydraulic Mount

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Chinese Journal of Mechanical Engineering 2021年第3期34卷 336-344页

作者： Yanhua Liu Xin Guan Pingping Lu Rui Guo State Key Laboratory of Automobile Simulation and Control Jilin UniversityChangchun 130022China

At present,research on hydraulic mounts has mainly focused on the prediction of the dynamic stiffness and loss *** to the traditional finite element analysis method,the programming method can be used to analyze hydraulic mounts for a rapid and accurate understanding of the influence of the different mounting parameters on the dynamic stiffness and loss *** aims of this study were to investigate the nonlinear dynamic characteristics of a hydraulic mount,and to identify the parameters that affect the dynamic stiffness and loss angle using MATLAB software programs to obtain the influence curves of the parameters,so as to use suitable parameters as the basis for vibration analysis.A nonlinear mechanical model of a hydraulic mount was established according to the basic principles of fluid *** dynamic stiffness and loss angle of the dimensionless expression were proposed.A numerical calculation method for the dynamic performance evaluation index of the hydraulic mount was derived.A one-to-one correspondence was established between the structural parameters and peak frequency of the evaluation *** accuracy and applicability of the mechanical model were verified by the test *** results demonstrated the accuracy of the nonlinear mechanical model of the hydraulic mount,and the vehicle driving comfort was greatly improved by the optimization of the structural parameters.

关键词： Hydraulic mount Vibration analysis Dynamic characteristics Calculation method

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Research on key Issues of Consistency Analysis of Vehicle Steering Characteristics

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Chinese Journal of Mechanical Engineering 2021年第2期34卷 123-134页

作者： Yanhua Liu Xin Guan Pingping Lu Rui Guo State Key laboratory of Automobile Simulation and Control Jilin UniversityChangchun 200240China

Given the global lack of effective analysis methods for the impact of design parameter tolerance on performance deviation in the vehicle proof-of-concept stage,it is difficult to decompose performance tolerance to design parameter *** study proposes a set of consistency analysis methods for vehicle steering *** process of consistency analysis and control of automotive performance in the conceptual design phase is proposed for the first time.A vehicle dynamics model is constructed,and the multi-objective optimization software Isight is used to optimize the steering performance of the *** analysis is used to optimize the design performance *** tolerance interval of the performance is obtained by comparing the original car performance value with the optimized *** the help of layer-by-layer decomposition theory and interval mathematics,automotive performance tolerance has been decomposed into design parameter *** simulation and real vehicle experiments,the validity of the consistency analysis and control method presented in this paper are *** decomposition from parameter tolerance to performance tolerance can be achieved at the conceptual design stage.

关键词： Interval mathematical theory Layer by layer decomposition theory Consistency of performance Multi-objective optimization

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Sludge-based biochar adsorbent:pore tuning mechanisms,challenges,and role in carbon sequestration

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Biochar 2023年第1期5卷 1419-1441页

作者： Md Manik Mian Wenya Ao Shubo Deng State Key Joint Laboratory of Environment Simulation and Pollution Control(SKLESPC) Beijing Key Laboratory for Emerging Organic Contaminants ControlSchool of EnvironmentTsinghua UniversityBeijing 100084China

Sludge biochar,a carbonized product of raw sludge,contains porous architectures that can act as epicenters for adsorbing external molecules through physical or chemical *** biochar also immobilizes innate micropollutants,which is advantageous over conventional sludge disposal *** date,numerous strategies have been discovered to improve sludge biochar morphology,but the influential factors,pore tuning mechanisms,and process feasibility remain *** knowledge gap limits our ability to design a robust sludge-based ***,we present state-of-the-art sludge biochar synthesis methods with insight into structural and chemical transformation *** and novel concepts for improving sludge biochar porous architecture are *** the first time,sludge biochar properties,adsorption performances,and techno-economic perspectives were compared with commercial activated carbon(AC)to reveal the precise challenges in sludge biochar *** importantly,sludge biochar role in carbon sequestration is detailed to demonstrate the environmental significance of this ***,the review concludes with an overview of prospects and an outlook for developing sludge biochar-based research.

关键词： Sludge-based adsorbent Micropores Feasible methods Challenges Carbon sequestration

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Micro-structure evolution, precipitation behavior and strengthening mechanism of Ni-Cr-Mo system steel fabricated via laser powder bed fusion and subsequent quenching control

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Chinese Journal of Aeronautics 2025年第3期38卷 560-592页

作者： Qing WANG Deyin KONG Shihui ZHOU Xingran LI Zhihui ZHANG The Key Laboratory of Bionic Engineering(Ministry of Education) Jilin UniversityChangchun 130025China Weihai Institute for Bionic Jilin UniversityWeihai 264402China State Key Laboratory of Automotive Simulation and Control Jilin UniversityChangchun 130025China

High-performance 24CrNiMo steel was fabricated using Laser Powder Bed Fusion (LPBF). Subsequent quenching treatment was applied and the influence of quenching temperatures on micro-structure evolution and properties was systematically characterised and analysed. The micro-structure of the as-built steel consisted of two parts. The first part comprised martensite with twins combined with ω-Fe nano-particles, and the second part consisted of lower bainite in the molten pool, as well as upper bainite, granular bainite and tempered martensite in the heat-affected zone. With the quenching temperatures varying from 800℃ to 950℃, the micro-structure gradually transformed from acicular ferrite + martensite to tempered martensite +θ-Fe3C carbides, and the grain size exhibited noticeable growth. Moreover, quenching treatments could eliminate the anisotropy and inhomogeneity of the micro-structure. The rod-shaped nanosized η-Fe2C and θ-Fe3C precipitates were clearly observed, which were converted from ω-Fe and distributed at multiple angles in the lath. The size and number of nano-precipitates, triggered by the high self-tempering degree of martensite, gradually increased. The relationships among grain size, the twins, dislocation density and nano-precipitation and the dramatically improved performance of quenched samples were analysed using strengthening mechanisms. After quenching at 850℃, the as-built 24CrNiMo steel attained ultra-high mechanical properties including hardness, Ultimate Tensile Strength (UTS), Elongation (El) and impact energy with values of 480.9 HV_(1), 1611.4 MPa, 9.8% and 42.8 J, respectively. Meanwhile, both the wear and thermal fatigue resistance increased by approximately 40%. This study demonstrated that LPBF-fabricated 24CrNiMo steel, with matching good performances, can be achieved using a subsequent one-step quenching process.

关键词： Laser powder bed fusion 24CrNIMo steel Quenching control Micro-structure evolution Precipitate Comprehensive properties Strengthening mechanisms

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Experimental Study on Impingement Processes of Fuel Sprays on Biomimetic Structured Surfaces

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Journal of Bionic Engineering 2024年第1期21卷 362-373页

作者： Yanling Chen Liang Guo Wanchen Sun Yuying Yan Rong Xuan Junfeng Zhang State Key Laboratory of Automotive Simulation and Control Jilin UniversityChangchun 130025China Faculty of Engineering University of NottinghamNottingham NG72RDUK

To improve the controllability of the wall-wetting process after the fuel spray-wall impingement in internal combustion engines,the methods of laser etching,chemical etching and surface free energy modification are used to prepare biomimetic structured surfaces with different *** impingement processes of diesel and n-butanol sprays on the walls under different conditions are experimentally *** the surface oleophilicity increases,the spreading radius of wall-impinging sprays *** about 5 s after the fuel injections,the fuel spray droplets hit the walls for the first time,and the secondary breakup and rebound *** mixture concentrations of different fuels hitting the various walls reach the peak *** a higher surface temperature,the peak value of the mixture concentration is mainly related to the heat flux to the fuel droplets in different boiling regimes from the metal *** concentration of the air–fuel mixture in the near wall region increases with increasing surface oleophilicity,increasing wall temperature and decreasing ambient *** with diesel,n-butanol presents a higher air–fuel mixture concentration in the near wall region.

关键词： Spray-wall impingement Morphological development Air-fuel mixture concentration Surface wettability Wall temperature:Ambient pressure

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Highly active copper-intercalated weakly crystallized δ-MnO_(2) for low-temperature oxidation of CO in dry and humid air

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Frontiers of Environmental Science & Engineering 2024年第5期18卷 127-136页

作者： Hao Zhang Huinan Li Pengyi Zhang Tingxia Hu Xianjie Wang State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing100084China Beijing Key Laboratory for Indoor Air Quality Evaluation and Control Beijing100084China Midea Corporate Research Center Foshan528311China

Copper intercalated birnessite MnO_(2)(δ-MnO_(2))with weak crystallinity and high specific surface area(421 m^(2)/g)was synthesized by a one-pot redox method and investigated for low-temperature CO *** molar ratio of Cu/Mn was as high as 0.37,which greatly weakened the Mn-O bond and created a lot of low-temperature active oxygen *** situ DRIFTS revealed strong bonding of copper ions with ***-synthesized MnO_(2)-150Cu achieved 100%conversion of 250 ppm CO in normal air(3.1 ppm H_(2)O)even at−10°C under the weight-hourly space velocity(WHSV)of 150 L/(g·h).In addition,it showed high oxygen storage capacity to oxidize CO in inert *** the concurrent moisture in air significantly inhibited CO adsorption and its conversion at ambient temperature,MnO_(2)-150Cu could stably convert CO in 1.3%moisture air at 70°C owing to its great low-temperature activity and reduced competitive adsorption of water with increased *** study discovers the excellent low-temperature activity of weakly crystallized δ-MnO_(2) induced by high content intercalated copper ions.

关键词： CO oxidation Birnessite Interlayer copper Low-temperature Oxygen storage capacity

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Experimental Study on the Effects of Ammonia Energy Substitution Rate on Combustion and Emission Performance in a Hydrogen Engine

Experimental Study on the Effects of Ammonia Energy Substitu...

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2024 Vehicle Powertrain Diversification Technology Forum, VPD 2024

作者： Wu, Weilong Xie, Fangxi Chen, Hong Du, Jiakun Li, Yong Guangzhou Automobile Group Co Ltd China State Key Laboratory of Automotive Simulation and Control China GAC Automotive Research & Development Center China

To advance the application of zero-carbon ammonia fuel, this paper presents an experimental investigation on the potential of ammonia substitution using a 2.0L ammonia-hydrogen engine, where ammonia is injected into the intake port and hydrogen is directly injected into the cylinder. The study examines the effects of ammonia substitution rate under various load conditions on engine combustion and emission performance. Results indicate that the maximum ammonia energy substitution rate reached 98%, and within the stable combustion boundary, the mass fraction of unburned ammonia was less than 3%. The ammonia energy substitution ratio increased with load, and ammonia addition significantly suppressed pre-ignition and knocking. As ammonia content increased, ignition timing advanced, combustion duration extended, ignition delay prolonged, COV increased, peak cylinder pressure, and pressure rise rate decreased, with a corresponding decrease in peak heat release rate. Compared to a pure hydrogen engine, the ammonia-hydrogen dual-fuel engine significantly improved brake thermal efficiency (BTE), which continued to rise with increasing ammonia energy substitution rate. At BMEP = 0.8 MPa, BTE reached a maximum of 41.1%. With increased ammonia addition, unburned NH3 emissions in the exhaust gradually increased, while NOx emissions decreased overall, but N2O emissions showed an increasing trend. © 2025 SAE International.

关键词： Hydrogen engines

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