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Effects of gravel on the water absorption characteristics and hydraulic parameters of stony soil

Journal of Arid Land 2024年第7期16卷 895-909页

作者： ma Yan WANG Youqi ma Chengfeng YUAN Cheng BAI Yiru Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China Ningxia UniversityYinchuan 750021China School of Geography and Planning Ningxia UniversityYinchuan 750021China School of Ecology and Environment Ningxia UniversityYinchuan 750021China

The eastern foothills of the Helan Mountains in China are a typical mountainous region of soil and gravel,where gravel could affect the water movement process in the *** study focused on the effects of different gravel contents on the water absorption characteristics and hydraulic parameters of stony *** stony soil samples were collected from the eastern foothills of the Helan Mountains in April 2023 and used as the experimental materials to conduct a one-dimensional horizontal soil column absorption *** experimental groups with gravel contents of 0%,10%,20%,30%,40%,and 50%were established to determine the saturated hydraulic conductivity(K_(s)),saturated water content(θ_(s)),initial water content(θ_(i)),and retention water content(θ_(r)),and explore the changes in the wetting front depth and cumulative absorption volume during the absorption *** Philip model was used to fit the soil absorption process and determine the soil water absorption *** the length of the characteristic wetting front depth,shape coefficient,empirical parameter,inverse intake suction and soil water suction were derived from the van Genuchten ***,the hydraulic parameters mentioned above were used to fit the soil water characteristic curves,unsaturated hydraulic conductivity(K_(θ))and specific water capacity(C(h)).The results showed that the wetting front depth and cumulative absorption volume of each treatment gradually decreased with increasing gravel *** with control check treatment with gravel content of 0%,soil water absorption rates in the treatments with gravel contents of 10%,20%,30%,40%,and 50%decreased by 11.47%,17.97%,25.24%,29.83%,and 42.45%,*** the gravel content increased,inverse intake suction gradually increased,and shape coefficient,K_(s),θ_(s),andθ_(r)gradually *** the same soil water content,soil water suction and K_(θ)gradually decreased with increasing gravel *** the same soil water s

关键词： stony soil gravel content water absorption characteristics hydraulic parameters one-dimensional horizontal soil column absorption experiment van Genuchten model eastern foothills of Helan Mountains

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Effect of Cryogenic Treatment on Microstructure and Tribological Property Evolution of Electron Beam Melted Ti6Al4V

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Journal of Wuhan University of Technology(materials Science) 2024年第4期39卷 1010-1017页

作者：黄西娜 ma Xiaowen XU Tianyi School of Mechanical and Electrical Engineering China University of Mining and Technology-BeijingBeijing 100083China School of Engineering and Technology China University of GeosciencesBeijing 100083China

Cryogenic treatment was used to improve the tribological properties of Ti6Al4V artificial hip joint *** treatment at-196℃with different holding time were carried out on Ti6Al4V specimens fabricated using electron beam melting(EBM),and their microstructure and tribological properties evolution were systematically analyzed by scanning electron microscopy(SEM),vickers hardness,and wear *** experimental results show that the as-fabricated specimen consists of lamellarαphase andβcolumnar ***,the thickness of lamellarαphase decreased after cryogenic *** addition,it can be found that the fineαphase was precipitated and dispersed between the lamellarαphase with the holding time *** hardness shows a trend of first increasing and then *** wear rate of the specimen cryogenic treated for 24 h is the minimum and the average friction coefficient is 0.50,which is reduced by 14.61%compared with the *** wear mechanism of the as-fabricated specimen is severe exfoliation,adhesive,abrasive,and slight fatigue ***,the specimen cryogenic treated for 24 h shows slight adhesive and abrasive *** can be concluded that it is feasibility of utilizing cryogenic treatment to reduce the wear of EBMed Ti6Al4V.

关键词： electron beam melting(EBM) cryogenic treatment microstructure vickers hardness tribological property

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Bioinspired nanomaterials for the treatment of bacterial infections

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Nano Research 2024年第2期17卷 691-714页

作者： Xiaojing ma Wenjing Tang Rong Yang Robert F.Smith School of Chemical&Biomolecular Engineering Cornell UniversityIthacaNY 14853USA

Infectious diseases pose a serious threat to global *** immunizations can control most viral infections,bacterial infections,particularly those caused by drug-resistant strains,continue to cause high rates of illness and ***,the creation of new antibiotics has come to a grinding halt in the last ten *** response to this crisis,nanotechnology has emerged as a hopeful solution to tackle drug resistance and enhance treatment results.A large variety of biomimetic nanomaterials,termed nanozymes,have demonstrated strong antimicrobial *** the inherent toxicity of nanomaterials is a concern,recent studies have harnessed the stimuli-responsiveness of nanomaterials to enable local and/or targeted delivery to reduce the treatment side ***,the physicochemical versatility of nanomaterials affords many degrees of freedom that enable rational design of smart or autonomous therapeutics,which cannot be achieved using conventional *** design straddles the fields of catalysis,nanoscience,microbiology,and translational *** provide an overview of this interdisciplinary landscape,this review is organized based on composition into lipid,metal,metal oxide,and non-metallic *** as a delivery vehicle enhance bioavailability and reduce ***-and metal oxide-based nanomaterials inhibit bacterial growth by mimicking natural enzymatic activities such as peroxidase(POD)and ***,carbon-,polymer-,and cell membrane-based nanomaterials are combined into a discussion on non-metallic *** the end of this review,potentially fruitful directions for future bioinspired nanomaterials in infectious disease treatment are included.

关键词： bioinspired nanomaterial bacteria infectious disease antimicrobial liposome nanozyme

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Numerical investigation on characteristics of interfacial wave of liquid film in gas-liquid two-phase flow using OpenFOAM

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Chinese Journal of Aeronautics 2024年第2期37卷 233-248页

作者： Xiaoqi ma Yueshe WANG Jiaming TIAN State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

Liquid film cooling as an advanced cooling technology is widely used in space *** operation of liquid film along the rocket combustion inner wall is crucial for thermal protection of rocket *** stability of liquid film is mainly determined by the characteristics of interfacial wave,which is rarely investigated right *** to improve the stability of thin film has become a hot *** view of this,an advanced model based on the conventional Volume of Fluid(VOF)model is adopted to investigate the characteristics of interfacial wave in gas-liquid flow by using OpenFOAM,and the mechanism of formation and development of wave is revealed intuitively through numerical *** effects from gas velocity,surface tension and dynamic viscosity of liquid(three factors)on the wave are studied *** can be found that the gas velocity is critical to the formation and development of wave,and four modes of droplets generation are illustrated in this ***,a gas vortex near the gas-liquid interface can induce formation of wave easily,so changing the gas vortex state can regulate formation and development of ***’s more,the change rules of three factors influencing on the interfacial wave are obtained,and the surface tension has a negative effect on the formation and development of wave only when the surface tension coefficient is above the critical value,whereas the dynamic viscosity has a positive effect in this ***,the maximum height and maximum slope angle of wave will level off as the gas velocity ***,the maximum slope angle of wave is usually no more than 38°,no matter what happens to the three factors.

关键词： Interfacial wave Gas-liquid Two-phase flow VOF model OpenFOAM

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Access to High-Molecular-Weight Polyethylenes through High Temperature Ethylene Polymerization Catalysed by Ethylene-Bridged ansa-(3-R-Cyclopentadienyl)(Fluorenyl) Zirconocene Complexes

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Chinese Journal of Polymer Science 2024年第1期42卷 42-51,I0007页

作者： Bo Li Haiyan ma Jiling Huang Shanghai Key Laboratory of Functional materials Chemistry and Laboratory of Organometallic Chemistry School of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai 200237China

A series of C1-symmetric ethylene-bridged ansa-(3-R-cyclopentadienyl)(fluorenyl) metallocene complexes(Zr: 1-5;Hf: 6) have been synthesized, characterized and investigated as catalyst precursors for the high temperature ethylene polymerization. Using methylaluminoxane(maO) as the cocatalyst, zirconium complexes 1-5 bearing a bulky substituent on the 3-position of the cyclopendienyl ring showed high catalytic activities up to 1.48×10^(7) g PE·mol_(Zr)^(-1)·h^(-1) toward the polymerization of ethylene and afforded polyethylenes with high molecular weights(1.49×10^(5)-6.31×10^(5) g/mol), meanwhile exhibting great thermal stability at high temperatures up to 120 ℃ together with a long catalytic life time up to 2 h. By adopting low Al/Zr ratios, such as 125, polyethylenes with ultra high molecular weights up to 2.86×106 g/mol were obtained. It is worthy of noting that zirconium complexes 1-4 bearing a substituent with an aryl pendant showed temperature-dependent activities, which increased rapidly with the increase of polymerization temperature, thus weak interaction of the pendent aryl group with the cationic active center is proposed to account for the very low activities displayed at low temperatures. In contrast to zirconocene complexes 1-5, hafnocene complex 6 only displayed very low catalytic activities toward the polymerization of ethylene and afforded polyethylenes with molecular weights ten times smaller than those obtained by zirconocene complexes 1-5. Zirconocene complexes 1-5 were also able to catalyse the polymerization of propylene at high temperatures, but only afforded waxes with low molecular weights.

关键词： ansa-Metallocene Ethylene Propylene Polymerization High temperature

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狭缝涂布大面积氧化锌薄膜的制备及其在柔性有机太阳能电池中的应用

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复合材料学报 2022年第5期39卷 1976-1985页

作者：郭经波韩云飞龚超潘雅琴刘立起骆群马昌期上海大学材料科学与工程学院上海200438 中国科学院苏州纳米技术与纳米仿生研究所创新实验室苏州215123

发展有机太阳能电池的印刷法制备技术是实现有机光伏产业化的关键。在有机光伏器件中,氧化锌是常用的电子传输层材料。氧化锌纳米粒子在印刷过程中的自聚集,以及大面积薄膜干燥的不均匀,严重影响了大面积印刷有机光伏器件的性能。通过... 详细信息

发展有机太阳能电池的印刷法制备技术是实现有机光伏产业化的关键。在有机光伏器件中,氧化锌是常用的电子传输层材料。氧化锌纳米粒子在印刷过程中的自聚集,以及大面积薄膜干燥的不均匀,严重影响了大面积印刷有机光伏器件的性能。通过调控氧化锌墨水溶剂和引入墨水分散添加剂,获得一种适用于大面积涂布的氧化锌纳米墨水。其中复合溶剂的使用调控了氧化锌墨水的流变特性,进而改善了涂布薄膜中的边缘效应;而乙醇胺添加剂的引入解决了墨水在存放和印刷过程中的聚集问题。该墨水具有18个月以上保存稳定性,以及优异的狭缝涂布适印性。基于上述墨水,采用狭缝涂布方法制备获得的100×100 mm^(2)尺寸的大面积涂布薄膜具有优异的均匀性。将印刷的大面积氧化锌薄膜作为柔性有机太阳能电池的电子传输层,获得1 cm^(2)柔性有机太阳能电池的效率超过了14%,同时表现优异的重复性。

关键词：有机太阳能电池印刷光伏狭缝涂布氧化锌纳米墨水大面积均匀性

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Effects of baffle position in serpentine flow channel on the performance of proton exchange membrane fuel cells

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Chinese Journal of Chemical Engineering 2024年第5期69卷 250-262页

作者： Guodong Xia Xiaoya Zhang Dandan ma MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation Beijing Key Laboratory of Heat Transfer and Energy ConversionBeijing University of TechnologyBeijing 100124China

This study used a three-dimensional numerical model of a proton exchange membrane fuel cell with five types of channels:a smooth channel(Case 1);eight rectangular baffles were arranged in the upstream(Case 2),midstream(Case 3),downstream(Case 4),and the entire cathode flow channel(Case 5)to study the effects of baffle position on mass transport,power density,net power,***,the effects of back pressure and humidity on the voltage were *** showed that compared to smooth channels,the oxygen and water transport facilitation at the diffusion layer-channel interface were added 11.53%-20.60%and 7.81%-9.80%at 1.68 A·cm^(-2)by adding *** closer the baffles were to upstream,the higher the total oxygen flux,but the lower the flux uniformity the worse the water *** oxygen flux of upstream baffles was 8.14%higher than that of downstream baffles,but oxygen flux uniformity decreased by 18.96%at 1.68 A·cm^(-2).The order of water removal and voltage improvement was Case 4>Case 5>Case 3>Case 2>Case *** power of Case 4 was 9.87%higher than that of the smooth *** the Case 4,when the cell worked under low back pressure or high humidity,the voltage increments were *** potential increment for the back pressure of 0 atm was 0.9%higher than that of 2 atm(1 atm=101.325 kPa).The potential increment for the humidity of 100%was 7.89%higher than that of 50%.

关键词： Proton exchange membrane fuel cell Baffle position mass transfer Net power Uniformity Voltage increment

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Measuring Financial Systemic Risk:Net Liability Clearing Mechanism and Contagion Effect

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Journal of Systems Science & Complexity 2024年第3期37卷 1114-1146页

作者： ma Jiali ZHU Shushang LI Duan College of Big Data Statistics Guizhou University of Finance and EconomicsGuiyang 550025China School of Business Sun Yat-Sen UniversityGuangzhou 510275China School of Data Science City University of Hong KongHong Kong 999077China

Following the framework of E-N model(Eisenberg and Noe,2001),the authors consider a new clearing mechanism based on net liabilities among financial institutions since the liabilities between the counterparties should be deducted accordingly when clearing in *** the basis for systemic risk measurement,similar to the original E-N model,the authors first establish some good properties for the clearing payment vector according to a more general ***,the authors investigate how risk spreads among institutions through the liability network forming the risk contagion ***,the authors illustrate with a specific example that the original E-N clearing mechanism may misidentify the systemic important institutions,and theoretically show that it may also overestimate the risk compared with the netting clearing mechanism.

关键词： Clearing mechanism contagion net liability network systemic risk

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Electrical stimulation for brighter persistent luminescence

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Light(Science & Applications) 2024年第8期13卷 1590-1601页

作者： Xilin ma Yuhua Wang Takatoshi Seto Key Laboratory for Special Function materials and Structural Design of the Ministry of Education National&Local Joint Engineering Laboratory for Optical Conversion Materials and Technology of National Development and Reform CommissionDepartment of Materials ScienceSchool of Materials and EnergyLanzhou UniversityNo.222South Tianshui RoadLanzhouGansu 730000China

An immature understanding of the mechanisms of persistent luminescence(PersL)has hindered the development of new persistent luminescent materials(PersLMs)with increased *** this regard,in-situ direct current(DC)electric field measurements were conducted on a layered structure composed of the SrAl_(2)O4:Eu^(2+),Dy^(3+)phosphor,and an *** this study,the photoluminescence(PL)and afterglow properties were investigated with respect to voltage by analyzing the current signal and thermoluminescence(TL)*** intensity of PersL increased due to a novel phenomenon known as“external electric field stimulated enhancement of initial brightness of afterglow”.This dynamic process was illustrated via the use of a rate equation approach,where the electrons trapped by the ultra-shallow trap at 0.022 eV could be transferred through the conduction band during long *** afterglow intensity could reach 0.538 cdm^(-2)at a 6 V electric *** design of an electric field stimulation technique enables the enhancement of the intensity of PersLMs and provides a new perspective for exploring the fundamental mechanics of certain established PersLMs.

关键词： spectroscopy. luminescence conduction

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Scientific and technological innovations of wastewater treatment in China

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Frontiers of Environmental Science & Engineering 2024年第6期18卷 43-48页

作者： Hui Huang Rui ma Hongqiang Ren State Key Laboratory of Pollution Control and Resource Reuse School of the EnvironmentNanjing UniversityNanjing 210023China

The“dual-carbon”strategy promotes the development of the wastewater treatment sector and is an important tool for leading science and technology *** on the global climate change and the new policies introduced by China,this paper described the new needs for the development of wastewater treatment science and *** offered a retrospective analysis of the historical trajectory of scientific and technological advancements in this *** bibliometrics,it delineated the research hotspots within wastewater treatment,notably highlighting materials genomics,artificial intelligence,and synthetic ***,it posited that,in the future,the field of wastewater treatment should follow the paths of technological innovations with multi-dimensional needs,such as carbon reduction,pollution reduction,health,standardisation,and *** purpose of this paper was to provide references and suggestions for scientific and technological innovations in the field of wastewater treatment,and to contribute to the common endeavor of moving toward a Pollution-Free Planet.

关键词： Wastewater treatment Dual-carbon strategy Technological innovation Carbon reduction

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