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Multi-physics multi-scale simulation of unique equiaxed-to-columnar-to-equiaxed transition during the whole solidification process of Al-Li alloy laser welding

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Journal of materials Science & Technology 2024年第4期171卷 235-251页

作者： chu han Ping Jiang Shaoning Geng Liangyuan Ren School of Mechanical Science and Engineering Huazhong University of Science&Technology(HUST)Wuhan430074China

In this study,a novel multi-physics multi-scale model with the dilute multicomponent phase-field method in three-dimensional(3D)space was developed to investigate the complex microstructure evolu-tion in the molten pool during laser welding of Al-Li *** accurately compute mass data within both two and three-dimensional computational domains,three efficient computing methods,including central processing unit parallel computing,adaptive mesh refinement,and moving-frame algorithm,were *** was placed on the distinctive equiaxed-to-columnar-to-equiaxed transition phenomenon that occurs during the entire solidification process of Al-Li alloy laser *** results indi-cated that the growth distance of columnar grains that epitaxially grew from the base metal(BM)de-creased as the nucleation rate *** the nucleation rate increased,the morphology of the newly formed grains near the fusion boundary(FB)changed from columnar to equiaxed,and newly formed equiaxed grains changed from having high-order dendrites to no obvious dendrite *** the nucleation rate was sufficiently high,non-dendritic equiaxed grains could directly form near the FB,and there was nearly no epitaxial growth from the ***,simulation results illustrated the com-petition among multiple grains with varying orientations that grow in 3D space near the ***,how equiaxed grain bands develop was *** equiaxed band not only hindered the growth of early columnar grains but also some of its grains could grow epitaxially to form new columnar *** predicted results were in good agreement with experimental measurements and observations.

关键词： Laser welding Al-Li alloy Equiaxed-to-columnar-to-equiaxed transition Multi-physics multi-scale model Multicomponent alloys 3D phase-field model

The Multi-parameter Test of Gravitational Wave Dispersion with Principal Component Analysis

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Research in Astronomy and Astrophysics 2024年第5期24卷 140-150页

作者： Zhi-chu ma Rui Niu Wen Zhao CAS Key Laboratory for Research in Galaxies and Cosmology Department of AstronomyUniversity of Science and Technology of ChinaHefei 230026China School of Astronomy and Space Sciences University of Science and Technology of ChinaHefei 230026China

In this work, we consider a conventional test of gravitational wave(GW) propagation which is based on the phenomenological parameterized dispersion relation to describe potential departures from General Relativity(GR)along the propagation of GWs. But different from tests conventionally performed previously, we vary multiple deformation coefficients simultaneously and employ the principal component analysis(PCA) method to remedy the strong degeneracy among deformation coefficients and obtain informative posteriors. The dominant PCA components can be better measured and constrained, and thus are expected to be more sensitive to potential departures from the waveform model. Using this method we analyze ten selected events and get the result that the combined posteriors of the dominant PCA parameters are consistent with GR within 99.7% credible intervals. The standard deviation of the first dominant PCA parameter is three times smaller than that of the original dispersion parameter of the leading order. However, the multi-parameter test with PCA is more sensitive to not only potential deviations from GR but also systematic errors of waveform models. The difference in results obtained by using different waveform templates hints that the demands of waveform accuracy are higher to perform the multiparameter test with PCA. Whereas, it cannot be strictly proven that the deviation is indeed and only induced by systematic errors. It requires more thorough research in the future to exclude other possible reasons in parameter estimation and data processing.

关键词： gravitational waves-gravitation-black hole physics

A confined growth strategy to construct 3DOM SiO_(2) nanoreactor insitu embedded Co_(3)O_(4) nanoparticles catalyst for the catalytic combustion of VOCs:Superior H_(2)O and SO_(2) resistance

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Nano Research 2024年第1期17卷 207-220页

作者： Weigao han Shilin Wu Fang Dong Weiliang han Yinghao chu Linghui Su Zhicheng Tang State Key Laboratory for Oxo Synthesis and Selective Oxidation National Engineering Research Center for Fine Petrochemical IntermediatesLanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China Dalian National Laboratory for Clean Energy Dalian 116023China College of Architecture and Environment Sichuan UniversityChengdu 610000China

SO_(2)poisoning is a common problem in the catalytic combustion of volatile organic compounds(VOCs).In this work,we took three-dimensionally ordered macroporous and mesoporous(3DOM)SiO_(2)as the nanoreactor to protect active sites from SO_(2)erosion in the catalytic combustion of ***,the confined growth of metal active nanoparticles in the multi-stage pore is also full of *** we successfully confined Co_(3)O_(4)nanoparticles(NPs)in macroporous and mesoporous ***,the precursors’growth in the pore was controlled and nanoreactors with different pore sizes were prepared by adjusting the loading amount and preparation *** is discovered that the Co_(3)O_(4)NPs confined in 3DOM SiO_(2)nanoreactor showed superior sulfur and water *** functional theory(DFT)calculations verified that the Co-Si catalyst had high SO_(2)adsorption energy(-0.48 eV),which illustrated that SO_(2)was hard to attach to the surface of the Co-Si *** SiO_(2)nanoreactor had low SO_(2)adsorption energy(-5.15 eV),which indicated that SO_(2)was easily absorbed on SiO_(2)*** illustrated that the SiO_(2)nanoreactor could protect effectively active sites from SO_(2)erosion.

关键词： zeolitic imidazolate frameworks(ZIFs) Co_(3)O_(4) benzene catalytic combustion nanoreactor sulfur and water resistance

Hydration lubrication modulated by water structure at TiO2–aqueous interfaces

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Friction 2024年第4期12卷 591-605页

作者： Pingsu ma Yuan LIU Ke han Yu TIAN Liran ma State Key Laboratory of Tribology in Advanced Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China

The nature of solid-liquid interfaces is of great significance in *** advances have been made in lubrication based on hydration ***,a detailed molecular-level understanding is still ***,we investigated water molecule behaviors at the TiO2-aqueous interfaces by the sum-frequency generation vibrational spectroscopy(SFG-VS)and atomic force microscope(AFM)to elucidate the fundamental role of solid-liquid interfaces in *** contributions of water structures and hydration effects were revealed,where water structures played the dominant role in lubrication for TiO2 surfaces of varying hydrophilicity,while hydration effects dominated with the increasing of ion *** lubrication is observed on the initial TiO2 surfaces with strongly H-bonded water molecules compared to the hydrophilic TiO2 surfaces with more disordered *** stable ordered water arrangement with strong hydrogen bonds and the shear plane occurring between the ordered water layer and subsequent water layer may play a significant role in achieving lower *** adsorbed hydrated molecules with the increasing ionic concentration perturb ordered water but lead to the enhancement of hydration effects,which is the main reason for the improved lubrication for both *** work provides more insights into the detailed molecular-level understanding of the mechanism of hydration lubrication.

关键词： hydration lubrication interfacial water structures hydration effects titanium dioxide(TiO2)

Transient state analysis of a rub-impact rotor system during maneuvering flight

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Chinese Journal of Aeronautics 2024年第7期37卷 236-251页

作者： Jun WANG Yunfei LIU Zhaoye QIN Liang ma Fulei chu Beijing Key Laboratory of Health Monitoring and Self-Recovery for High-End machinery Equipment Beijing University of Chemical TechnologyBeijing 100029China State Key Laboratory of Tribology Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China College of Aeronautical Engineering Civil Aviation University of ChinaTianjin 300300China

maneuvering flight substantially affects the dynamic behavior of rotors;particularly,such flight may cause rubbing between a rotor and stator,which is one of the most serious damages in aircraft *** this paper,a nonlinear dynamic model for describing the dynamic characteristics of a rub-impact rotor system during maneuvering flight is established based on the Lagrange ***,numerical simulations employing the Newmark method are performed,delving into the detailed discussion of the influence of parameters such as rotational speed and maneuvering flight on the transient and steady-state responses of the rotor *** effect mechanism of maneuver load and its coupling with rub impact is *** results show that the impact response induced by maneuvering flight is more obvious in the subcritical state than in the supercritical *** additional stiffness and damping are also induced;in particular,the additional damping has a coupling ***,the rub impact imposes an additional constraint on the rotor system,thereby weakening the influence of the maneuver load and becoming the major factor that determines the dynamic behavior of the rotor system at high speeds.

关键词： maneuvering flight Rub impact Rotor system Dynamic response Impact response

Enzyme-driven Nanorobots Walking Along Predesigned Tracks on the DNA Origami for Cargo Transport and Catalysis

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Chemical Research in Chinese Universities 2024年第2期40卷 333-342页

作者： NIE Cunpeng ma Tianran CHEN Tingting chu Xia State Key Laboratory of Chemo/Bio-Sensing and Chemometrics College of Chemistry and Chemical EngineeringHunan UniversityChangsha410082P.R.China

In molecular engineering,designing and synthesizing molecular machines with capable of performing complex tasks,remains a formidable *** is an excellent candidate for building molecular robots because it is highly ***,we present an artificial nanorobot,in which a DNA cube serves as the inert‘body’,and nucleic acid catalysts based on an enzymatic nicking reaction act as the‘legs’for *** nanorobot can execute a series of actions,such as‘start’,‘turn’,and‘stop’when it walks along a predefined *** performance could be confirmed and monitored by using an atomic force microscope(AFM)and fluorescence *** by biological machines,we artificially designed a series of specialized tasks that combined walking with control of cargo transport and ***-time fluorescence kinetics curves provide monitoring signals for cargo transport and catalytic *** work can enrich the toolbox of DNA machinery and has great potential for engineering molecular nanofactories.

关键词： DNA origami DNA nanorobot Controlled cargo transport DNAzyme catalysis

A review of CFD simulation in pressure driven membrane with fouling model and anti-fouling strategy

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Frontiers of Environmental Science & Engineering 2024年第8期18卷 1-29页

作者： Shiyong Miao Jiaying ma Xuefei Zhou Yalei Zhang Huaqiang chu State Key Laboratory of Pollution Control and Resource Reuse Tongji UniversityShanghai 200092China Shanghai Institute of Pollution Control and Ecological Security Tongji UniversityShanghai 200092China

Pressure-driven membrane filtration systems are widely utilized in wastewater treatment,desalination,and water reclamation and have received extensive attention from *** fluid dynamics(CFD)offers a convenient approach for conducting mechanistic studies of flow and mass transfer characteristics in pressure-driven *** a signature phenomenon in membrane systems,the concentration polarization that accompanies the permeation process is a key factor in membrane performance degradation and membrane fouling *** fouling models(scaling,biofouling and colloidal particle fouling)based on CFD theory have been constructed,and considerable research has been *** representative antifouling strategies with special simulation methods,including patterned membranes,vibration membranes,rotation membranes,and pulsatile flows,have also been *** studies should focus on refining fouling models while considering local hydrodynamic characteristics;experimental observation tools focusing on the internal structure of inhomogeneous fouling layers;techno-economic model of antifouling strategies such as vibrational,rotational and pulsatile flows;and unfavorable hydraulic phenomena induced by rapidly changing flows in simulations.

关键词： Computational fluid dynamics Membrane Fouling model Concentration polarization

Photoinduced superlubricity on TiO_(2) surfaces

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Friction 2024年第3期12卷 428-438页

作者： Ke han Liran ma Yu TIAN Jianbin LUO State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China Received:16 September 2022/Revised:28 October 2022/Accepted:27 December 2022The author(s)2022.

Superlubricity control is of great interest in both industry and scientific research,and several methods have been proposed to achieve this *** this work,ultraviolet(UV)light was introduced into titanium dioxide(TiO_(2))and silicon nitride(Si_(3)N_(4))tribosystems to accomplish photoinduced *** friction coefficients(COFs)between Si_(3)N_(4) balls and TiO_(2) plates in the mixtures of sulfuric acid(H^(2)SO_(4))solution and glycerol solution were obviously reduced,and the system entered the superlubricity region(COFhan that with UV *** formation of silica(SiO_(2))layers on the surfaces of Si_(3)N_(4) balls and the elastohydrodynamic effects were determined to be fundamental to the low friction in this experiment,and the enhancement of the combination between the TiO_(2) surface and the hydroxy group of glycerol by UV illumination was the key to the photoinduced superlubricity in this *** findings showed one method for achieving superlubricity by introducing a light field that could be further applied to special working conditions.

关键词： light control friction superlubricity glycerol titanium dioxide(TiO_(2))

Bio-Based Waterborne Poly(Vanillin-Butyl Acrylate)/MXene Coatings for Leather with Desired Warmth Retention and Antibacterial Properties

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Engineering 2024年第5期36卷 250-263页

作者： Jianzhong ma Li ma Lei Zhang Wenbo Zhang Qianqian Fan Buxing han College of Bioresources Chemical and materials Engineering Shaanxi University of Science and TechnologyXi’an 710021China Xi’an Key Laboratory of Green Chemicals and Functional materials Xi’an 710021China College of Chemistry and Chemical Engineering Shaanxi University of Science and TechnologyXi’an 710021China Shaanxi Collaborative Innovation Center of Industrial Auxiliary Chemistry and Technology Shaanxi University of Science and TechnologyXi’an 710021China Institute of Chemistry Chinese Academy of SciencesBeijing 100190China

This study presents a solvent-free,facile synthesis of a bio-based green antibacterial agent and aromatic monomer methacrylated vanillin(MV)using *** resulting MV not only imparted antibacterial properties to coatings layered on leather,but could also be employed as a green alternative to petroleum-based carcinogen styrene(St).Herein,MV was copolymerized with butyl acrylate(BA)to obtain waterborne bio-based P(MV-BA)miniemulsion via miniemulsion ***,MXene nanosheets with excellent photothermal conversion performance and antibacterial properties,were introduced into the P(MV-BA)miniemulsion by ultrasonic *** the gradual solidification of P(MV-BA)/MXene nanocomposite miniemulsion on the leather surface,MXene gradually migrated to the surface of leather coatings due to the cavitation effect of ultrasonication and amphiphilicity of MXene,which prompted its full exposure to light and bacteria,exerting the maximum photothermal conversion efficiency and significant antibacterial *** particular,when the dosage of MXene nanosheets was 1.4 wt%,the surface temperature of P(MV-BA)/MXene nanocomposite miniemulsioncoated leather(PML)increased by about 15℃ in an outdoor environment during winter,and the antibacterial rate against Escherichia coli and Staphylococcus aureus was nearly 100%under the simulated sunlight treatment for 30 ***,the introduction of MXene nanosheets increased the air permeability,water vapor permeability,and thermal stability of these *** study provides a new insight into the preparation of novel,green,and waterborne bio-based nanocomposite coatings for leather,with desired warmth retention and antibacterial *** can not only realize zerocarbon heating based on sunlight in winter,reducing the use of fossil fuels and greenhouse gas emissions,but also improve ability to fight off invasion by harmful bacteria,viruses,and other microorganisms.

关键词： MXene nanosheets Vanillin Styrene substitute Leather coating Photothermal conversion Warmth retention Antibacterial properties