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Photoluminescence of ZnS Clusters in Zeolite-y

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Journal of Materials Science & Technology 1997年第5期13卷 397-404页

作者： chen, W Wang, ZG Lin, ZJ Xu, y Lin, Ly Lab. of Semiconductor Materials Sciences Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China

Two obvious emissions are observed from the ZnS clusters encapsulated in zeolite-y. The emission around 355 nm is sharp and weak, locating at the onset of the absorption edge. The band around 535 nm is broad, strong and Stokes-shifted. Both the two emissions shift to blue and their intensities firstly increase then decrease as the loading of ZnS in zeolite-y or clusters size decreases. Through investigation, the former is attributed to the excitonic fluorescence, and the latter to the trapped luminescence from surface states. The cluster size-dependence of the luminescence may be explained qualitatively by considering both the carrier recombination and the nonradiative recombination rates. Four peaks appearing in the excitation spectra are assigned to the transitions of 1S-1S, 1S-1P, 1S-1D and surface state, respectively. The excitation spectra of the clusters do not coincide with their absorption spectra. The states splitted by quantum-size confinement are detected in the excitation spectra, but could not be differentiated in the optical absorption spectra due to inhomogeneous broadening. The size-dependence of the excitation spectra is similar to that of the absorption spectra. Both the excitation spectra of excitonic and of trapped emissions are similar, but change in relative intensity and shift in position are observed.

关键词： Zeolites

Reversal of the magnetoelectric effect at a ferromagnetic metal/ferroelectric interface induced by metal oxidation

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npj Computational Materials 2021年第1期7卷 1890-1896页

作者： Zhaojin chen Qiong yang Lingling Tao Evgeny y.Tsymbal School of Materials Science and Engineering Xiangtan UniversityXiangtanHunan 411105China Department of Physics and Astronomy University of NebraskaLincolnNE 68588USA

Multiferroic materials composed of ferromagnetic and ferroelectric components are interesting for technological applications due to sizable magnetoelectric coupling allowing the control of magnetic properties by electric *** to being compatible with the silicon-based technology,HfO2-based ferroelectrics could serve as a promising component in the composite ***,a strong charge-mediated magnetoelectric coupling has been predicted for a Ni/HfO_(2) multiferroic ***,using density functional theory calculations,we systematically study the effects of the interfacial oxygen stoichiometry relevant to experiments on the magnetoelectric effect at the Ni/HfO_(2) *** demonstrate that the magnetoelectric effect is very sensitive to the interface stoichiometry and is reversed if an oxidized Ni monolayer is formed at the *** reversal of the magnetoelectric effect is driven by a strong Ni−O bonding producing exchange-split polarization-sensitive antibonding states at the Fermi *** argue that the predicted reversal of the magnetoelectric effect is typical for other 3d ferromagnetic metals,such as Co and Fe,where the metal-oxide antibonding states have an opposite spin polarization compared to that in the pristine ferromagnetic *** results provide an important insight into the mechanism of the interfacial magnetoelectric coupling,which is essential for the physics and application of multiferroic heterostructures.

关键词： ferromagnetic ferroelectric bonding

Surface hydrophobicity: effect of alkyl chain length and network homogeneity

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Frontiers of Chemical Science and Engineering 2021年第1期15卷 90-98页

作者： Wenqian chen Vikram Karde Thomas N.H.cheng Siti S.Ramli Jerry y.y.Heng Department of Chemical Engineering Imperial College LondonLondonSW72AZUK Department of Food Technology Faculty of Applied SciencesUniversiti Teknologi MARA(UiTM)Shah AlamSelangorMalaysia

Understanding the nature of hydrophobicity has fundamental importance in environmental *** spherical silica nanoparticles(diameter=369±7 nm)as the model material,the current study investigates the relationship between the alkyl chain network and *** alkyl silanes with different chain length(triethoxymethylsilane(C1)***(octyl)silane(C8))were utilised separately for the functionalisation of the *** contact angle and inverse gas chromatography results show that the alkyl chain length is essential for controlling hydrophobicity,as the octyl-functionalised nanoparticles were highly hydrophobic(water contact angle=150.6°±6.6°),whereas the methyl-functionalised nanoparticles were hydrophilic(i.e.,water contact angle=0°,similar to the pristine nanoparticles).The homogeneity of the octyl-chain network also has a significant effect on hydrophobicity,as the water contact angle was reduced significantly from 148.4°±3.5°to 30.5°±1.0°with a methyl-/octyl-silane mixture(ratio=160:40µL·g^(–1) nanoparticles).

关键词： hydrophobicity surface energy wettability alkyl chain network silica nanoparticle

PM_(2.5) in China:Measurements,sources,visibility and health effects,and mitigation

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Particuology 2014年第2期12卷 1-26页

作者： David y.H.Pui Sheng-Chieh chen Zhili Zuo Department of Mechanical Engineering College of Science and EngineeringUniversity of Minnesota

Concern over the health effects of fine particles in the ambient environment led the U.S. Environmental Protection Agency to develop the first standard for PM2.5 （particulate matter less than 2.5 μm） in 1997. The Particle Technology Laboratory at the University of Minnesota has helped to establish the PM2.5 standard by developing many instruments and samplers to perform atmospheric measurements. In this paper, we review various aspects of PM2.5, including its measurement, source apportionment, visibility and health effects, and mitigation. We focus on PM2.s studies in China and where appropriate, compare them with those obtained in the U.S. Based on accurate PM2.5 sampling, chemical analysis, and source apportionment models, the major PM2.5 sources in China have been identified to be coal combustion, motor vehicle emissions, and industrial sources. Atmospheric visibility has been found to correlate well with PM2.s concentration. Sulfate, ammonium, and nitrate carried by PM2.s, commonly found in coal burning and vehicle emissions, are the dominant contributors to regional haze in China. Short-term exposure to PM2.s is strongly associated with the increased risk of morbidity and mortality from cardiovascular and respiratory diseases in China. The strategy for PMzs mitigation must be based on reducing the pollutants from the two primary sources of coal-fired power plants and vehicle emissions. Although conventional Particulate Emission Control Devices （PECD） such as electrostatic precipitators in Chinese coal-fired power plants are generally effective for large particles, most of them may not have high collection efficiency of PM2.5. Baghouse filtration is gradually incorporated into the PECD to increase the PM2.5 collection efficiency. By adopting stringent vehicle emissions standard such as Euro 5 and 6, the emissions from vehicles can be gradually reduced over the years. An integrative approach, from collaboration among academia, government, and industries, can effe

关键词： PM2.5 in ChinaAtmospheric particle size distributionPM2.5 samplingChemical composition of PM2.sSource apportionment modelsPM2.5 health impactPM2.s mitigationCoal-fired power plantParticle emission control devices (PECD)Baghouse filtrationIntegrative approach

Role of iron ore in enhancing gasification of iron coke:Structural evolution,influence mechanism and kinetic analysis

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International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 58-69页

作者： Jie Wang Wei Wang Xuheng chen Junfang Bao Qiuyue Hao Heng Zheng Runsheng Xu School of Chemistry and Materials Science Hubei Engineering UniversityXiaogan 432000China Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education Wuhan University of Science and TechnologyWuhan 430081China Institue of Ironmaking Technology Baosteel Central Research InstituteShanghai 201999China State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

The utilization of iron coke provides a green pathway for low-carbon *** uncover the influence mechanism of iron ore on the behavior and kinetics of iron coke gasification,the effect of iron ore on the microstructure of iron coke was ***,a comparative study of the gasification reactions between iron coke and coke was conducted through non-isothermal thermogravimetric *** findings indicate that compared to coke,iron coke exhibits an augmentation in micropores and specific surface area,and the micropores further extend and *** provides more adsorption sites for CO_(2) molecules during the gasification process,resulting in a reduction in the initial gasification temperature of iron *** the heating rate in non-isothermal gasification can enhance the reactivity of iron *** metallic iron reduced from iron ore is embedded in the carbon matrix,reducing the orderliness of the carbon structure,which is primarily responsible for the heightened reactivity of the carbon *** kinetic study indicates that the random pore model can effectively represent the gasification process of iron coke due to its rich pore ***,as the proportion of iron ore increases,the activation energy for the carbon gasification gradually decreases,from 246.2 kJ/mol for coke to 192.5 kJ/mol for iron coke 15wt%.

关键词： low-carbon ironmaking iron coke gasification structural evolution kinetic model

Recent Advances in Computational Simulation of Macro-,Meso-,and Micro-Scale Biomimetics Related Fluid Flow Problems

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Journal of Bionic Engineering 2007年第2期4卷 97-107页

作者： y. y. yan School of the Built Environment The University of Nottingham Nottingham NG7 2RD UK

Over the last decade, computational methods have been intensively applied to a variety of scientific researches and engineering designs. Although the computational fluid dynamics （CFD） method has played a dominant role in studying and simulating transport phenomena involving fluid flow and heat and mass transfers, in recent years, other numerical methods for the simulations at meso- and micro-scales have also been actively applied to solve the physics of complex flow and fluid-interface interactions. This paper presents a review of recent advances in multi-scale computational simulation of biomimetics related fluid flow problems. The state-of-the-art numerical techniques, such as lattice Boltzmann method （LBM）, molecular dynamics （MD）, and conventional CFD, applied to different problems such as fish flow, electro-osmosis effect of earthworm motion, and self-cleaning hydrophobic surface, and the numerical approaches are introduced. The new challenging of modelling biomimetics problems in developing the physical conditions of self-clean hydrophobic surfaces is discussed.

关键词： biomimetics computational simulation macro- meso- micro-scale hydrophobic surfaces

An efficient SPH methodology for modelling mechanical characteristics of particulate composites

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Defence Technology（防务技术） 2021年第1期17卷 135-146页

作者： Z.J.Zheng S.Kulasegaram P.chen y.Q.chen Department of Mechanics College of Mechanical EngineeringChongqing University of TechnologyChongqing400054China Institute of Applied and Computational Mechanics Cardiff School of EngineeringCardiff UniversityQueen’s BuildingsThe ParadeCardiffCF243AAWalesUK Department of Mechanics and Engineering Science College of EngineeringPeking UniversityBeijing100871China

Particulate composites are one of the widely used materials in producing numerous state-of-the-art components in biomedical,automobile,aerospace including defence *** of modelling techniques have been adopted in the past to model mechanical behaviour of particulate *** to their favourable properties,particle-based methods provide a convenient platform to model failure or fracture of these *** particle hydrodynamics(SPH)is one of such methods which demonstrate excellent potential for modelling failure or fracture of particulate composites in a Lagrangian *** of the major challenges in using SPH method for modelling composite materials depends on accurate and efficient way to treat interface and boundary *** this paper,a masterslave method based multi-freedom constraints is proposed to impose essential boundary conditions and interfacial displacement constraints in modelling mechanical behaviour of composite materials using SPH *** proposed methodology enforces the above constraints more accurately and requires only smaller condition number for system stiffness matrix than the procedures based on typical penalty function approach.A minimum cut-off value-based error criteria is employed to improve the computational efficiency of the proposed *** addition,the proposed method is further enhanced by adopting a modified numerical interpolation scheme along the boundary to increase the accuracy and computational *** numerical examples demonstrate that the proposed master-slave approach yields better accuracy in enforcing displacement constraints and requires approximately the same computational time as that of penalty method.

关键词： Particulate composites SPH Essential boundary condition Multi-point constraints Master-slave method

Advances in therapies using mesenchymal stem cells and their exosomes for treatment of peripheral nerve injury:state of the art and future perspectives

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Neural Regeneration Research 2025年第11期20卷 3151-3171页

作者： Fatima Aldali Chunchu Deng Mingbo Nie Hong chen Department of Rehabilitation Medicine Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhanHubei ProvinceChina Department of Orthopedics Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhanHubei ProvinceChina

“Peripheral nerve injury”refers to damage or trauma affecting nerves outside the brain and spinal *** nerve injury results in movements or sensation impairments,and represents a serious public health *** severed peripheral nerves have been effectively joined and various therapies have been offered,recovery of sensory or motor functions remains limited,and efficacious therapies for complete repair of a nerve injury remain *** emerging field of mesenchymal stem cells and their exosome-based therapies hold promise for enhancing nerve regeneration and *** stem cells,as large living cells responsive to the environment,secrete various factors and *** latter are nano-sized extracellular vesicles containing bioactive molecules such as proteins,microRNA,and messenger RNA derived from parent mesenchymal stem *** have pivotal roles in cell-to-cell communication and nervous tissue function,offering solutions to changes associated with cell-based *** ongoing investigations,mesenchymal stem cells and mesenchymal stem cell-derived exosome-based therapies are in the exploratory stage.A comprehensive review of the latest preclinical experiments and clinical trials is essential for deep understanding of therapeutic strategies and for facilitating clinical *** review initially explores current investigations of mesenchymal stem cells and mesenchymal stem cell-derived exosomes in peripheral nerve injury,exploring the underlying ***,it provides an overview of the current status of mesenchymal stem cell and exosomebased therapies in clinical trials,followed by a comparative analysis of therapies utilizing mesenchymal stem cells and ***,the review addresses the limitations and challenges associated with use of mesenchymal stem cell-derived exosomes,offering potential solutions and guiding future directions.

关键词： clinical trials exosome extracellular vesicles mesenchymal stem cells nerve regeneration peripheral nerve injury pre-clinical experiments

Characterization for Fusion Candidate Vanadium Alloys

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Plasma Science and Technology 2004年第4期6卷 2395-2399页

作者： T.Muroga T.Nagasaka J.M.chen Z.y.Xu Q.y.Huang y.C.Wu NationalInstituteforFusionScience Toki509-5292Japan SouthwesternInstituteofPhysics Chengdu610041China InstituteofPlasmaPhysics ChineseAcademyofSciencesHefei230031China

This paper summarizes recent achievements in the characterization ofcandidate vanadium alloys obtained for fusion in the framework of the Japan-China Core UniversityProgram. National Institute for Fusion Science (NIFS) has a program of fabricating high-purityV-4Cr-4Ti alloys. The resulting products (NIFS-HEAT-1,2), were characterized by various researchgroups in the world including Chinese partners. South Western Institute of Physics (SWIP) fabricateda new V-4Cr-4Ti alloy (SWIP-Heat), and carried out a comparative evaluation of hydrogenembrittlement of NIFS-HEATs and SWIP-Heat. The tensile test of hydrogen-doped alloys showed that theNIFS-HEAT maintained the ductility to relatively high hydrogen levels. The comparison of the datawith those of previous studies suggested that the reduced oxygen level in the NIFS-HEATs should beresponsible for the increased resistance to hydrogen embrittlement. Based on the chemical analysisdata of NIFS-HEATs and SWIP-Heats, neutron-induced activation was analyzed in Institute of PlasmaPhysics (IPP-CAS) as a function of cooling time after the use in the fusion first wall. The resultsshowed that the low level of Co dominates the activity up to 50 years followed by a domination of Nbor Nb and Al in the respective alloys. It was suggested that reduction of Co and Nb, both of whichare thought to have been introduced via cross-contamination into the alloys from the molds usedshould be crucial for reducing further the activation.

关键词： vanadium alloys characterization nuclear fusion