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The onset of surface-enhanced Raman scattering for single-particle detection of submicroplastics

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Journal of Environmental Sciences 2022年第11期34卷 58-64页

作者： Cheng-Hao lee james Kar-Hei Fang Department of Applied Biology and Chemical Technology The Hong Kong Polytechnic UniversityKowloonHong Kong SARChina Institute of Textiles and Clothing The Hong Kong Polytechnic UniversityKowloonHong Kong SARChina Research Institute for Future Food The Hong Kong Polytechnic UniversityKowloonHong Kong SARChina State Key Laboratory of Marine Pollution City University of Hong KongKowloonHong Kong SARChina

Microplastics represent an emerging environmental problem worldwide, raising ecological and food safety concerns. Compared to microplastics, there is growing evidence of an even higher abundance of submicro-and nanoplastics in the environment, but a reliable monitoring method for detecting these smaller-sized plastics is lacking. Herein we presented the application of surface-enhanced Raman scattering(SERS) for this purpose. Particles of polystyrene(PS;600 nm) were used as the probe analyte. Gold nanourchins(Au NU;50 nm),i.e. urchin-shaped nanoparticles with irregular spikes around the core, were used as the SERS-active substrate. The effectiveness of SERS on PS was evaluated at a single-particle level with different numbers of Au NU in order to determine the minimum conditions required for the onset of the SERS effect. Our findings suggest that SERS of a single particle of PS can be induced by as few as 1–5 particles of Au NU, and that the use of excitation wavelength at 785 nm is appropriate to meet the red-shifted surface plasmon resonance of Au NU upon aggregation. These specifications provide additional information for the development of SERS-based tools for detecting plastic particles < 1 μm in food and environmental samples.

关键词： Microplastics Nanoplastics Gold nanourchins SERS Food contamination

Micromorphic theory:a gateway to nano world

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International Journal of Smart and Nano Materials 2010年第2期1卷 115-135页

作者： Xianqiao Wang james D.lee Department of Mechanical and Aerospace Engineering The George Washington UniversityWashingtonDC 20052USA

Micromorphic theory(MMT)envisions a material body as a continuous collection of deformable particles;each possesses finite size and inner *** is considered as the most successful top-down formulation of a two-level continuum model,in which the deformation is expressed as a sum of macroscopic continuous deformation and internal microscopic deformation of the inner *** this work,the kinematics including the objective Eringen tensors is *** laws are derived by requiring the energy equation to be form-invariant under the generalized Galilean *** concept of material force and the balance law of pseudomomentum are generalized for *** axiomatic approach is demonstrated in the formulation of constitutive equations for a generalized micromorphic thermoviscoelastic solid,generalized micromorphic fluid,micromorphic plasticity,and micromorphic electromagnetic-thermoelastic *** of MMT in micro/nanoscale are discussed.

关键词： micromorphic theory Eringen tensors constitutive theory generalized micromorphic solid/fluid electromagnetic-thermoelastic coupling micro/nanomechanics

CONVEX CONTROLLER DESIGN APPLIED TO AC INDUCTION MOTOR TO SATISFY MULTIPLE SIMULTANEOUS SPECIFICATIONS

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Chinese Journal of Mechanical Engineering 2006年第4期19卷 475-479页

作者： lee Seung-Ju SUN Dong MILLS james K Department of Mechanical and Industrial Engineering University of Toronto Toronto MSS 3G8 Canada Department of Manufacturing Engineering and Engineering Management City University of Hong Kong Hong Kong SAR China

The application of a closed-loop specification oriented feedback control design method, which addresses the design of controllers to satisfy multiple simultaneous conflicting closed-loop performance specifications is presented. The proposed approach is well suited to the design of controllers which must meet a set of conflicting performance specifications. Gain tuning is central to the design process, however, the tuning process is greatly simplified over that presented by the problem of tuning a PID controller for example. The proposed control method is applied to an AC induction motor, with an inner-loop flux vector controller applied to design a position control system. Experimental results verify the effectiveness of this method.

关键词： Convex controller design Multiple simultaneous specifications AC induction motor Nonlinear control

Porous ternary complex metal oxide nanoparticles converted from core/shell nanoparticles

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Nano Research 2016年第4期9卷 996-1004页

作者： Jaewon lee Huazhang Zhu Gautam Ganapati Yadav james Caruthers Yue Wu School of Chemical and Environmental Engineering Shanghai Institute of Technology Shanghai200235 China School of Chemical Engineering Purdue University 480 Stadium Mall Drive West Lafayette IN 47907 USA Department of Chemical and Biological Engineering Iowa State University Sweeney Hall Ames IA 50011 USA Present address: Energy Institute City College of New York New York NY 10031 USA

We demonstrate an easy and scalable low-temperature process to convert porous ternary complex metal oxide nanoparticles from solution-synthesized core^shell metal oxide nanopartides by thermal annealing. The final products demonstrate superior electrochemical properties with a large capacity and high stability during fast charging/discharging cycles for potential applications as advanced lithium-ion battery （LIB） electrode materials. In addition, a new breakdown mechanism was observed on these novel electrode materials.

关键词： ternary complex metal oxide porous nanopartide lithium-ion battery core/shell nanoparticles

Distinct MLT asymmetry of auroral kilometric radiation observed by the FAST satellite

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Earth and Planetary Physics 2025年第1期9卷 188-193页

作者： JiaWen Tang Sai Zhang FuLiang Xiao HongMing Yang Si Liu YiHua He Chang Yang YuYue Jin ZhouKun Deng Ping Li Archie james Johnston School of Physics and Electronic Sciences Changsha University of Science and TechnologyChangsha 410114China Hunan Province Higher Education Key Laboratory of Modeling and Monitoring on the Near-Earth Electromagnetic Environments Changsha University of Science and TechnologyChangsha 410114China School of Electrical and Information Engineering Changsha University of Science and TechnologyChangsha 410114China

Auroral Kilometric Radiation(AKR)is a common radio emission,which can contribute to the magnetosphere−ionosphere−atmosphere *** emissions have been observed in all magnetic planet magnetospheres of the solar *** this study,using observations from the FAST satellite from 30 August 1996 to 9 September 2001,the distribution of AKR in altitude=500−4500 km and invariant latitude(|ILAT|)=60°−80°has been analyzed.63045 AKR samples have been identified with~48%(52%)samples on the dayside(nightside).Of considerable interest,there is a distinct MLT asymmetry with the high occurrence rate in MLT=05−08 and 18−22(02−05 and 12−17)in the northern(southern)*** distinct MLT asymmetry is associated with the direction of Bxof the interplanetary magnetic *** addition,the occurrence rate on the nightside clearly increases as the index *** study further enriches *** and understanding of AKR in the magnetosphere as well as other similar radio emissions.

关键词： asymmetry auroral kilometric radiation interplanetary magnetic field

Work conjugate strain of virial stress

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International Journal of Smart and Nano Materials 2016年第1期7卷 39-51页

作者： Leyu Wang Jiaoyan Li james D.lee Center for Collision Safety and Analysis College of ScienceGeorge Mason UniversityFairfaxVAUSA School of Engineering Brown UniversityProvidenceRIUSA Department of Mechanical and Aerospace Engineering The George Washington UniversityWashingtonDCUSA

Certain stress tensor and strain tensor form a conjugate pair if there exists a scalar valued strain energy function such that the stress tensor is equal to the derivative of strain energy function with respect to the strain *** stress is widely accepted as the stress measurement in molecular dynamics(MD).However,its conjugate strain is not yet *** atomic logarithmic strain is proposed and numerically verified as the conjugate strain of virial stress at 0 K *** strain energy is calculated by virial stress and the proposed atomic logarithmic strain equals to the interatomic potential energy *** conclusion is numerically verified with(1)Coulomb-Buckingham potential,Lenard-Jones potential,or arbitrary nonlinear pair potential and(2)randomly generated atomic configurations and deformation *** are given in determining the stress–strain relation for magnesium oxide with MD *** result shows that the atomic logarithmic strain is identical to engineer-ing strain when deformation is small.

关键词： Thermodynamic pair conjugacy virial stress atomic logarithmic strain molecular dynamics interatomic potential strain energy magnesium oxide

Work conjugate pair of stress and strain in molecular dynamics

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International Journal of Smart and Nano Materials 2016年第3期7卷 144-178页

作者： Leyu Wang james D.lee Cing-Dao Kan Center for Collision Safety and Analysis College of ScienceGeorge Mason UniversityFairfaxVAUSA Department of Mechanical and Aerospace Engineering the George Washington UniversityWashingtonDC 20052USA

Certain stress and strain form a thermodynamic conjugate pair such that their strain energy equals to a scalar-valued potential *** atomistic stresses and strains are analytically derived based on the work conjugate *** is numerically verified with both two-body and three-body potentials that the atomistic Kirchhoff stress,first-order Piola–Kirchhoff stress and second-order Piola–Kirchhoff stress are conjugates to atomistic logarithmic strain,deformation gradient and Lagrangian strain,*** stress at 0 K based on original volume is the special form of atomistic Kirchhoff stress for pair *** is numerically verified that Hencky strain is not conjugate to any stress.

关键词： Thermodynamic conjugacy logarithmic strain atomistic stress deformation gradient strain energy interatomic potential Tersoff potential atomistic first-order Piola-Kirchhoff stress atomistic second-order Piola-Kirchhoff stress atomistic Kirchhoff stress virial stress

Catalyst-free synthesis and mechanical characterization of TaC nanowires

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Science China(Physics,Mechanics & Astronomy) 2021年第5期64卷 43-53页

作者： Shiliang Wang Liang Ma james lee Mead Shin-Pon Jui Guodong Li Han Huang School of Physics and Electronics Central South University Changsha 410083China School of Mechanical and Mining Engineering.The University of Queensland Brisbane QLD 4072Australia Deparment of Computing Science University of OldenburgOldenburg D-26129Germany Deparment of Mechanical and Electro-Mechanical Engineering Sun Yat-sen UniversiyKaohsiung 804China Deparment of Medicinal and Applied Chemistry Kaohsiung Medical UniversityKaohsiung 807China State Key Laboratory of Powder Metallurgw Central South UniversityChangsha 410083China

TaC nanowires are expected to be an ideal reinforcing material in ultra-high-temperature ceramics. However, their growth mechanisms and mechanical properties remain unclear, and low-cost large-scale synthesis has not been realised. In this study,bulk synthesis of [100]-oriented TaC nanowires is accomplished by carbothermal synthesis through a direct vapor-solid mechanism. Thermal resonance test results show that the synthesized square TaC nanowires with cross-sectional side-lengths of 65 to 497 nm have a size-independent Young’s modulus of(510.6±12.6) GPa;very close to the corresponding values of their bulk counterparts, but differing considerably from previously published measurements. Molecular dynamics(MD) simulations show that TaC nanowires with side-lengths of above 15 nm have a constant Young’s modulus of 517 GPa, and size effects on the modulus values should only occur at side-lengths below 15 nm. During bending tests, the TaC nanowires fracture into several segments in a brittle mode, and exhibit an increasing fracture strain from 1.88% to 4.28% as their side-length decreases from 489 to 90 nm. Weibull statistics analyses and TEM observations indicate that the failure of the nanowires should be primarily dependent on the number and size of surface defects. MD simulations further reveal that the defect-free TaC nanowires fail brittlely at a theoretical strain up to 5.76%.

关键词： tantalum carbide nanowires carbothermal synthesis vapor-solid mechanism mechanical properties

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避世之所加拿大亚瑟住宅

室内设计与装修 2025年第1期 46-49页

作者：无 james Brittain(摄影) coco(编译) 5468796 Architecture 不详

亚瑟住宅是为一对来自南非的夫妇设计的,他们一位是热衷园艺的木匠,另一位是急诊室医生。夫妇俩一直在寻找一个适中的“避难所”,与外界隔绝,并且有足够的空间来保护隐私。住宅所在的小区是一个成熟社区,原有的小平房正迅速被传统住宅... 详细信息

亚瑟住宅是为一对来自南非的夫妇设计的,他们一位是热衷园艺的木匠,另一位是急诊室医生。夫妇俩一直在寻找一个适中的“避难所”,与外界隔绝,并且有足够的空间来保护隐私。住宅所在的小区是一个成熟社区,原有的小平房正迅速被传统住宅取代。与此相反,亚瑟夫妇希望用一种深思熟虑的替代方案来挑战这种发展模式。

关键词：传统住宅替代方案保护隐私避难所亚瑟园艺小区加拿大