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Exceptional points enhance sensing in silicon micromechanical resonators

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Microsystems & Nanoengineering 2024年第1期10卷 17-25页

作者： Man-Na Zhang Lei Dong Li-Feng Wang Qing-An Huang key laboratory of MEMS of the ministry of education Southeast UniversityNanjing 210096China

Exceptional points(EPs)have recently emerged as a new method for engineering the response of open physical systems,that is,systems that interact with the environment.The systems at the EPs exhibit a strong response to a small perturbation.Here,we show a method by which the sensitivity of silicon resonant sensors can be enhanced when operated at EPs.In our experiments,we use a pair of mechanically coupled silicon micromechanical resonators constituting a parity-time(PT)-symmetric dimer.Small perturbations introduced on the mechanically coupled spring cause the frequency to split from the EPs into the PT-symmetric regime without broadening the two spectrum linewidths,and this frequency splitting scales with the square root of the perturbation strength.The overall signal-tonoise ratio is still greatly enhanced,although the measured noise spectral density of the EP sensing scheme has a slight increase comparable to the traditional counterpart.Our results pave the way for resonant sensors with ultrahigh sensitivity.

关键词： resonant symmetric points

Carbon emission quantification and reduction in pavement use phase:A review

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Journal of Traffic and Transportation engineering(English Edition) 2024年第1期11卷 69-91页

作者： Linjie Zhu Jin Li Feipeng Xiao key laboratory of Road and Traffic engineering of ministry of education Tongji UniversityShanghai 201804China

The carbon emissions arising from road pavement infrastructures have emerged as critical issue in recent years.The life cycle of a pavement can be divided into five phases,namely raw materials and production,construction,use,maintenance and end of life.While the use phase generates the highest carbon emissions throughout the pavement's life cycle,it is usually neglected in most pavement life cycle assessment(LCA)studies due to its complexity and uncertainty.Therefore,this review selected 126 relevant references,focuses on quantification methods,influential factors and reduction technologies of carbon emissions in pavement use phase.Among the carbon accounting approached,the LCA approach,remains the most widely used for evaluating the environmental impact of pavements.Second,the primary influential factors on the use phase'carbon emission include pavement-vehicle interaction primarily affected by pavement roughness,pavement albedo and climate change.Most influential factors above indirectly cause changes in carbon emissions by influencing the pavement performance and subsequent vehicle emissions.Finally,the review surveys carbon emission reduction technologies during pavement use phase,focusing mainly on reducing pavement rolling resistance and constructing cool pavements.Reflective pavements and permeable pavements are the most widely used cool pavement technologies.Overall,the aspects involved in this paper hold significant promise for quantifying and reducing carbon emissions in the pavement use phase.

关键词： Pavement Carbon emission Life cycle assessment Use phase Emission reduction

Mitochondria-targeted nano-AIEgens as a powerful inducer for evoking immunogenic cell death

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Chinese Chemical Letters 2024年第5期35卷 338-343页

作者： Kun-Heng Li Hong-Yang Zhao Dan-Dan Wang Ming-Hui Qi Zi-Jian Xu Jia-Mi Li Zhi-Li Zhang Shi-Wen Huang key laboratory of biomedical Polymers of ministry of education Department of ChemistryWuhan UniversityWuhan 430072China

AIEgens can serve as an effective platform for the construction of photosensitizer-based immunogenic cell death(ICD)inducers.To date,several mitochondria or endoplasmic reticulum(ER)-targeted aggregationinduced emission(AIE)molecules have been developed and have evoked massive ICD in cells.However,due to the complex physicochemical environment in cells,these small AIE molecules cannot maintain a stable aggregate state,which not only affects the fluorescence intensity of the photosensitizer but also decreases the generation of reactive oxygen species(ROS),and thus reducing the effect of the photosensitizer to elicit ICD.AIEgen-based nanomicelles,which maintain a stable micellar structure,can prevent defects of AIE molecules in photodynamic therapy(PDT)applications.Therefore,in this study,a mitochondria-targeted AIE nanophotosensitizer was synthesized and used as a highly potent ICD inducer for vaccine preparation and tumor prevention.

关键词： Aggregation induced emission Photodynamic therapy Immunogenic cell death Reactive oxygen species Nanophotosensitizer Mitochondria

Integrated multi-scale approach combining global homogenization and local refinement for multi-field analysis of high-temperature superconducting composite magnets

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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 747-762页

作者： Hanxiao GUO Peifeng GAO Xingzhe WANG key laboratory of Mechanics on Western Disaster and Environment of ministry of education Key Laboratory of Special Function Materials and Structure Design of Ministry of EducationCollege of Civil Engineering and MechanicsLanzhou UniversityLanzhou 730000China

Second-generation high-temperature superconducting(HTS)conductors,specifically rare earth-barium-copper-oxide(REBCO)coated conductor(CC)tapes,are promising candidates for high-energy and high-field superconducting applications.With respect to epoxy-impregnated REBCO composite magnets that comprise multilayer components,the thermomechanical characteristics of each component differ considerably under extremely low temperatures and strong electromagnetic fields.Traditional numerical models include homogenized orthotropic models,which simplify overall field calculation but miss detailed multi-physics aspects,and full refinement(FR)ones that are thorough but computationally demanding.Herein,we propose an extended multi-scale approach for analyzing the multi-field characteristics of an epoxy-impregnated composite magnet assembled by HTS pancake coils.This approach combines a global homogenization(GH)scheme based on the homogenized electromagnetic T-A model,a method for solving Maxwell's equations for superconducting materials based on the current vector potential T and the magnetic field vector potential A,and a homogenized orthotropic thermoelastic model to assess the electromagnetic and thermoelastic properties at the macroscopic scale.We then identify“dangerous regions”at the macroscopic scale and obtain finer details using a local refinement(LR)scheme to capture the responses of each component material in the HTS composite tapes at the mesoscopic scale.The results of the present GH-LR multi-scale approach agree well with those of the FR scheme and the experimental data in the literature,indicating that the present approach is accurate and efficient.The proposed GH-LR multi-scale approach can serve as a valuable tool for evaluating the risk of failure in large-scale HTS composite magnets.

关键词： epoxy-impregnated high-temperature superconducting(HTS)magnet multi-scale method global homogenization(GH) local refinement(LR) multi-field analysis

A toroidal SAW gyroscope with focused IDTs for sensitivity enhancement

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Microsystems & Nanoengineering 2024年第2期10卷 47-56页

作者： Lu Tian Haitao Zhao Qiang Shen Honglong Chang ministry of education key laboratory of Micro and Nano Systems for Aerospace School of Mechanical EngineeringNorthwestern Polytechnical UniversityXi’an710072China

A surface acoustic wave(SAW)gyroscope measures the rate of rotational angular velocity by exploiting a phenomenon known as the SAW gyroscope effect.Such a gyroscope is a great candidate for application in harsh environments because of the simplification of the suspension vibration mechanism necessary for traditional microelectromechanical system(MEMS)gyroscopes.Here,for the first time,we propose a novel toroidal standing-wave-mode SAW gyroscope using focused interdigitated transducers(FIDTs).Unlike traditional SAW gyroscopes that use linear IDTs to generate surface acoustic waves,which cause beam deflection and result in energy dissipation,this study uses FIDTs to concentrate the SAW energy based on structural features,resulting in better focusing performance and increased SAW amplitude.The experimental results reveal that the sensitivity of the structure is 1.51µV/(°/s),and the bias instability is 0.77°/s,which are improved by an order of magnitude compared to those of a traditional SAW gyroscope.Thus,the FIDT component can enhance the performance of the SAW gyroscope,demonstrating its superiority for angular velocity measurements.This work provides new insights into improving the sensitivity and performance of SAW gyroscopes.

关键词： angular deflection gyroscope

Compatibility evaluation between waterborne epoxy resin and SBR latex modified asphalt emulsion

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Journal of Traffic and Transportation engineering(English Edition) 2024年第1期11卷 160-171页

作者： Jianhua Yang Zhengqi Zhang Ying Fang key laboratory for Special Area Highway engineering of ministry of education Chang'an UniversityXi'an 710064China

Good compatibility between waterborne epoxy resin(WER)modifier and styrene-butadiene rubber(SBR)latex modified asphalt emulsion(SBRE)is an essential premise for good pavement performance of WER and SBR latex compositely modified asphalt emulsion(WSAE).This study aims to explore the compatibility between WER modifier and SBRE.To achieve the goal,several WER modifiers produced by two methods were first selected to modify SBRE,thus the WSAEs were prepared.Next,storage stability and workability of the WSAEs themselves,and high-temperature performance,rheological behavior and temperature sensitivity of their evaporated residues were compared and evaluated via performing a series of experiments,respectively,thus the WER modifier possessing an optimal modification effect was recommended.Results show that the storage stability of WSAEs is sensitive to the amount of WERs.The incorporation of 1%WERs by the mass of SBRE improves the storage stability of SBRE,while WERs that exceed 1%weaken its storage stability.When the WERs reach 3%and 4%,the 5 d storage stability of prepared WSAEs will be beyond the limitation of specification.Incorporating WERs into SBRE negatively affects the workability of SBRE,and the workability of WSAEs is adversely influenced by the WERs content and the storage time.To ensure the construction,the WSAEs with 3%and 4%WERs should not be stored for more than 36 h and 48 h,respectively.The WERs effectively improve the high-temperature performance of SBRE residue,especially the 3%WERs.Besides,the WERs notably enhance the rheological property and thermal stability of SBRE residue.In contrast,the WER modifier produced by chemically modified method has a smaller adverse impact on the storage stability and workability of WSAE,and a larger enhancement on the high-temperature performance,rheological property and thermal stability of SBRE residue,which is thus recommended to modify SBRE.

关键词： Waterborne epoxy resin SBR modified asphalt emulsion Workability Rheological property Temperature sensitivity Compatibility evaluation

Evidence-based practices in sustainable travel behavior intervention: A knowledge graph-based systematic review

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Journal of Traffic and Transportation engineering(English Edition) 2024年第2期11卷 293-311页

作者： Jian Li Chenjie Xu key laboratory of Road and Traffic engineering of the ministry of education College of Transportation EngineeringTongji UniversityShanghai 201804China

Sustainable travel behavior intervention is an essential strategy to promote the development of urban transportation.The interventions offer personalized strategies based on certain scenario and participants to promote its effectiveness over hard travel restrictions.However,personalized strategies may also bring about difficulties to identify the actual effect of the measures.Furthermore,based on current practice,to make full use of travel behavior interventions,it is necessary to construct a unified methodological evidencebased framework to assess the reliability and effectiveness of travel behavior intervention studies.In response to these issues,we applied evidence-based knowledge graph to the field of sustainable travel behavior interventions to help decision supporters design sustainable travel behavior interventions wisely and in turn avoid excessive use of hard travel restrictions.We introduced concept of evidence-based practice to conduct a systematic analysis concerning reliability and validity of current full volume empirical studies by dimensions of scenarios,types of interventions and targets.In addition,we took advantage of high extensivity and integrability of knowledge graph to organize evidence-based related elements.Result of the systematic analysis shows that in terms of reliability of evidence,school intervention is the best scenario,knowledge incentive is the best intervention type and promoting public transit and walking proportion are the best targets.Oppositely,the reliability of interventions in workplace,belonging to reward and threat along with aiming at changing travel patterns generally and lowering travel carbon emission need to be enhanced.From the study,various research prospects are raised to promote evidence quality in the field of travel behavior intervention implementation.As a pioneer study,our research contributes to the field of urban transportation in introducing concepts of evidence-based practice and enabling optimization and extension of our achievement via the usage of k

关键词： Evidence-based decision-making Evidence assessment Knowledge graph Travel behavior intervention Sustainable travel

Numerical study on the effective thermal conductivity and thermal tortuosity of porous media with different morphologies

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Science China Technological Sciences 2024年第6期67卷 1685-1694页

作者： DU Shen LI Dong LI Meng-Jie HE Ya-Ling key laboratory of Thermo-Fluid Science and engineering of ministry of education School of Energy and Power engineering Xi’an Jiaotong University

Effective thermal conductivity and thermal tortuosity are crucial parameters for evaluating the effectiveness of heat conduction within porous media. The direct pore-scale numerical simulation method is applied to investigate the heat conduction processes inside porous structures with different morphologies. The thermal conduction performances of idealized porous structures are directly compared with real foams across a wide range of porosity. Real foam structures are reconstructed using X-ray computed tomography and image processing techniques, while Kelvin and Weaire-Phelan structures are generated through periodic unit cell reconstruction. The detailed temperature fields inside the porous structures are determined by solving the heat conduction equation at the pore scale. The results present that the equivalent thermal conductivity of Kelvin and Weaire-Phelan structures is similar to and greater than that of the real foam structure with the same strut porosity. The thermal tortuosity of real foam structure is relatively larger and the heat conduction path becomes straighter by adopting the anisotropic design. The thermal tortuosity of the fluid channels for Kelvin, Weaire-Phelan, and real foam structures is close to one. The thermal conductivity of porous structures with heat transfer fluid increases as the thermal conductivity ratio of fluid to solid becomes larger. A small porosity of porous media leads to a larger equivalent thermal conductivity due to the dominant contribution of porous skeleton in the heat conduction process. Correlations derived from parallel and series models, as well as the Maxwell-Eucken models,provide decent predictions of effective thermal conductivity, with an average error of less than 8% in the entire range of thermal conductivity ratio.

关键词： volumetric solar receiver porous morphology direct pore-scale simulation equivalent thermal conductivity thermal tortuosity empirical correlation

Enhanced efficacy of CTLA-4 fusion anti-caries DNA vaccines in gnotobiotic hamsters

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Acta Pharmacologica Sinica 2007年第8期28卷 1236-1242页

作者： Feng ZHANG~3 Yu-hong LI~3 Ming-wen FAN~2 Rong JIA Qing-an XU Ji-hua GUO Fei YU Qi-wei TIAN key laboratory for Oral biomedical engineering of ministry of education,School and Hospital of Stomatology,Wuhan University,Wuhan 430079,China key laboratory for Oral biomedical engineering of ministry of education School and Hospital of Stomatology Wuhan University Wuhan China

Aim:To evaluate the comparative immunogenicity and protective efficacy of thecytotoxic T-lymphocyte-associated antigen 4(CTLA-4)fusion anti-caries DNAvaccines pGJA-P/VAX1,pGJA-P,and non-fusion anti-caries DNA constructpGLUA-P in hamsters.In addition,the ability of CTLA-4 to target pGJA-P/VAX 1-encoding antigen to dendritic cells was tested in vitro.Methods:All DNAconstructs contain genes encoding the A-P regions of a cell surface protein(PAc)and the glucan binding(GLU)domain of glucosyltransferases(GTFs)of cari-ogenic organism Streptococcus mutans.Human dendritic cells were mixed withthe CTLA-4-Ig-GLU-A-P protein expressed by pGJA-P/VAX1-transfected cellsand analyzed by flow cytometry.Gnotobiotic hamsters were immunized with anti-caries DNA vaccines by intramuscular injection or intranasal administration.Antibody responses to a representative antigen PAc were assayed by ELISA,andcaries protection was evaluated by keyes caries scores.Results:A flow cytometricanalysis demonstrated that CTLA-4-Ig-GLU-A-P protein was capable of bind-ing to human dendritic cells,pGJA-P/VAX1 and pGJA-P induced significantlyhigher specific salivary and serum anti-PAc antibody responses than pGLUA-ESignificantly fewer caries lesions were also observed in hamsters immunized withpGJA-P/VAX1 and pGJA-P.There was no significant difference in the anti-PAcantibody level or caries scores between pGJA-P/VAX1 and pGJA-P-immunizedgroups.Conclusion:Antigen encoded by CTLA-4 fusion anti-caries DNA vac-cine pGJA-P/VAX1 could specifically bind to human dendritic cells through theinteraction of CTLA-4 and B7 molecules.Fusing antigen to CTLA-4 has beenproven to greatly enhance the immunogenicity and protective efficacy of anti-caries DNA vaccines.

关键词： DNA vaccines Streptococcus mutans dendritic cells cytotoxic T-lymphocyteassociated antigen 4