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Magneto-mechanical effect of magnetic microhydrogel for improvement of magnetic neuro-stimulation

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Nano Research 2023年第5期16卷 7393-7404页

作者： Le Xue Qing Ye Linyuan Wu Dong Li Siyuan Bao Qingbo Lu Sha Liu Dongke Sun Zonghai Sheng Zhijun Zhang Ning Gu Jianfei Sun State Key Laboratory of Bioelectronics Jiangsu Key Laboratory of Biomaterials and DevicesSchool of Biological Science and Medical EngineeringSoutheast UniversityNanjing 210009China School of Mechanic Engineering Southeast UniversityNanjing 211189China Department of Neurology Affiliated Zhongda HospitalSchool of MedicineInstitution of NeuropsychiatrySoutheast UniversityNanjing 210009China Paul C.Lauterbur Research center for Biomedical Imaging Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong ProvinceShenzhen Key Laboratory of Ultrasound Imaging and TherapyCAS Key Laboratory of Health InformaticsInstitute of Biomedical and Health EngineeringShenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China Department of Mental Health and Public Health Faculty of Life and Health SciencesShenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China School of Medicine Nanjing UniversityNanjing 210008China

Superparamagnetic iron oxide(SPIO)nanoparticles play an important role in mediating precise and effective magnetic neurostimulation and can help overcome limitations related to penetration depth and spatial ***,nanoparticles readily diffuse in vivo,decreasing the spatial resolution and activation *** this study,we employed a microfluidic means to fabricate injectable microhydrogels encapsulated with SPIO nanoparticles,which significantly improved the stability of nanoparticles,increased the magnetic properties,reinforced the stimulation *** fabricated magnetic microhydrogels were highly uniform in size and sphericity,enabling minimally invasive injection into brain *** long-term residency in the cortex up to 22 weeks and the safety of brain tissue were shown using a mouse *** addition,we quantitatively determined the magneto-mechanical force yielded by only one magnetic microhydrogel using a video-based *** force was found to be within 7–8 pN under 10 Hz magnetic stimulation by both theoretical simulation and experimental ***,electrophysiological measurement of brain slices showed that the magnetic microhydrogels offer significant advantages in terms of neural activation relative to dissociative SPIO nanoparticles.A universal strategy is thus offered for performing magnetic neuro-stimulation with an improved prospect for biomedical translation.

关键词： magnetic stimulation superparamagnetic iron oxide(SPIO)nanoparticles magnetic microhydrogel long-term residency magneto-mechanical effect

Self-consistent mean field approximation and application in three-flavor NJL model

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Chinese Physics C 2020年第7期44卷 111-117页

作者：於子雄赵通宗红石 Department of physics Nanjing UniversityNanjing 210093China Department of physics AnHui Normal UniversityWuhu 241000China nanjing Proton Source Research and Design center Nanjing 210093China

In this study,we apply a self-consistent mean field approximation of the three-flavor Nambu–Jona-Lasinio(NJL)model and compare it with the two-flavor NJL *** self-consistent mean field approximation introduces a new parameter,α,that cannot be fixed in advance by the mean field approach *** to the lack of experimental data,the parameter,α,is ***,it is regarded as a free parameter and its influence on the chiral phase transition of strong interaction matter is studied based on this self-consistent mean field approximation.αaffects numerous properties of the chiral phase transitions,such as the position of the phase transition point and the order of phase ***,increasingαwill decrease the number densities of different quarks and increase the chemical potential at which the number density of the strange quark is ***,we observed thatαaffects the equation of state(EOS)of the quark matter,and the sound velocity can be calculated to determine the stiffness of the EOS,which provides a good basis for studying the neutron star mass-radius relationship.

关键词： chiral phase transition finite density NJL model self-consistent mean field approximation

Controlled vapour growth and phase engineering of large-area bilayer WSe2 for optoelectronic applications

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Progress in Natural Science:Materials International 2023年第6期33卷 947-953页

作者： Zhikang Ao Xiangdong Yang Xiang Lan Fen Zhang Yang Du Le Gao Xuyang Zhang Baihui Zhang Shunhui Zhang Tian Zhang Yinghao Chen Jianing Xie Wenkui Wen Chenyang Zha Huifang Ma Zhengwei Zhang College of Physics and Electronics Central South University School of Flexible Electronics(Future Technologies) & Institute of Advanced Materials(IAM) Jiangsu National Synergetic Innovation Center for Advanced MaterialsNanjing Tech University Institute of Micro/Nano Materials and Devices Ningbo University of Technology College of Materials Science and Engineering Hunan University College of Energy and Power Engineering Changsha University of Science and Technology Institute of applied Physics and Materials Engineering(IAPME) Zhuhai UM Science & Technology Research Institute(ZUMRI) University of Macau

The engineering of stacking order plays an important role in regulations of electronic and optical properties of layered van der Waals ***,we demonstrate a developed physical vapour deposition approach to grow WSe2 atomic layers with controllable 3R and 2H *** 3R WSe2bilayer tends to form at a lower deposition temperature(830℃),and the 2H WSe2bilayer prefers to grow at a higher deposition temperature(930℃).Efficient phase engineering was demonstrated by simply controlling the deposition ***,by photoluminescence,Raman,selected area electron diffraction and so on,it was determined that the AA’-stacking corresponds to the 2H phase,and the AB-stacking corresponds to the 3R ***,different layer stacking and interlayer coupling result in differences in the optical and optoelectronic properties of the two *** responsivity of 3R bilayer WSe2is ～195 times higher than 2H phase exhibiting dramatically improved photoelectric detection performance by phase engineering(R3R=2.54 A/W vs R2H=0.013 A/W at 780 nm,82.7 mW cm-2).Hence,the findings of this study not only contribute to the controllable synthesis of two-dimensional materials with diverse stacking phases but also hold promise for advancing the design and fabrication of future optoelectronic devices.

关键词： Transition metal dichalcogenides Phase engineering WSe_2 3R stacking Optoelectronics

Ensemble-based diurnally varying background error covariances and their impact on short-term weather forecasting

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Atmospheric and Oceanic Science Letters 2022年第6期15卷 22-28页

作者： Shiwei Zheng Yaodeng Chen Xiang-Yu Huang Min Chen Xianya Chen Jing Huang Key Laboratory of Meteorological Disaster of Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and TechnologyNanjingChina Institute of Urban Meteorology China Meteorological AdministrationBeijingChina

背景场误差协方差在资料同化系统中具有非常重要的作用,目前业务变分同化系统中常采用静态背景场误差协方差,未考虑其具体的日变化特征.为构建更为合理且便于业务系统应用的日变化背景误差协方差,本文构建了高分辨率集合预报样本的日变... 详细信息

背景场误差协方差在资料同化系统中具有非常重要的作用,目前业务变分同化系统中常采用静态背景场误差协方差,未考虑其具体的日变化特征.为构建更为合理且便于业务系统应用的日变化背景误差协方差,本文构建了高分辨率集合预报样本的日变化背景场误差协方差,揭示了其日变化特征,并应用到了CMA-BJ业务系统中,开展了基于业务框架的批量循环同化预报试验.结果表明,背景场误差存在明显的日变化特征,采用集合日变化背景场误差协方差能够改进模式的预报效果.

关键词：资料同化背景场误差协方差日变化集合方法

Study on modal characteristics and vibration reduction of an aircraft rotor–stator brake-induced squeal system

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Acta Mechanica Sinica 2020年第6期36卷 1350-1359,I0004页

作者： Qiaozhi Yin Xiaohui Wei Hong Nie Jian Deng State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing210016China Key Laboratory of Fundamental Science for National Defense-Advanced Design Technology of Flight Vehicle Nanjing University of Aeronautics and AstronauticsNanjing210016China nanjing center for Multifunctional Lightweight Materials and Structures Nanjing University of Aeronautics and AstronauticsNanjing210016China

Based on the modal coupling theory,the rotor and stator contact stiffness and axial relative velocity are considered to build an electric aircraft brake dynamic system model in this *** the complex modal analysis and transient dynamic analysis methods are used to study the aircraft brake squeal performance and vibratory *** unstable vibration modes indicate that the out-of-plane vibration plays an important role and the feed-in energy is larger than the output energy in the brake rotor–stator module so that brake squeal takes *** the influences of the contact stiffness,friction damping and frictional coefficient on the brake squeal system are carried out,laying the foundation for the three proposed vibration suppression *** show that the coefficient negative-slope condition will intensify the ***,a linear relationship between the squeal factor and the frictional coefficient is obtained to provide a guidance to predict squeal stability under more *** reduction design shows that adding a damping layer to the brake mechanism and chamfering the edge of braking stators both can reduce brake squeal effectively,while slotting braking stators is invalid in aircraft braking system.

关键词： Aircraft rotor-stator bake-induced vibration Brake squeal-Vibration stability Modal coupling Vibration suppression

Synthesis and magnetotransport properties of Bi2Se3 nanowires

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Chinese Physics B 2017年第9期26卷 324-328页

作者：张亢潘海洋魏仲夏张敏昊宋风麒王学锋张荣 National Laboratory of Solid State Microstructures Collaborative Innovation Center of Advanced MicrostructuresSchool of Electronic Science and EngineeringNanjing UniversityNanjing 210093China National Laboratory of Solid State Microstructures Collaborative Innovation Center of Advanced MicrostructuresSchool of PhysicsNanjing UniversityNanjing 210093China

Bi2Se3, as a three-dimensional topological insulator, has attracted worldwide attention for its unique surface states which are protected by time-reversal symmetry. Here we report the synthesis and characterization of high-quality singlecrystalline Bi2Se3 nanowires. Bi2Se3 nanowires were synthesized by chemical vapor deposition（CVD） method via goldcatalyzed vapor-liquid-solid（VLS） mechanism. The structure and morphology were characterized by scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, x-ray photoelectron spectroscopy（XPS）, and Raman spectroscopy. In magnetotransport measurements, the Aharonov–Bohm（AB） effect was observed in a nanowire-based nanodevice, suggesting the existence of surface states in Bi2Se3 nanowires.

关键词： topological insulators nanowires chemical vapor deposition Aharonov–Bohm effect

Temporal and Spatial Distribution Characteristics of Lightning Activity over the Pacific Ocean and Adjacent Land and Its Relationship with AOD and CAPE

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Journal of Tropical Meteorology 2022年第4期28卷 473-488页

作者：初雨郭凤霞张志伟邹迪可吴泽怡刘舟鲁鲜 Key Laboratory of Meteorological Disaster Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environment Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)/Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological AdministrationNanjing University of Information Science and TechnologyNanjing 210044 China

Based on LIS/OTD gridded lightning climatology data,ERA5 reanalysis data,and MODIS atmosphere monthly global products,we examined latitudinal and daily variations of lightning activity over land,offshore areas,open sea,and all marine areas(i.e.,the aggregate of open sea and offshore areas)for different seasons over the Pacific Ocean and the adjacent land areas at 65°N-50°S,99°E-78°W,and analysed the relationships of lightning activity with CAPE(Convective Available Potential Energy)and AOD(Aerosol Optical Depth).At any given latitude,the lightning density is the highest over land,followed by offshore areas,all marine areas and the open sea in *** lightning density over land is approximately an order of magnitude greater than that over all marine *** activity over land,offshore areas,open sea,and all marine areas varies with *** diurnal variation of lightning density over land has a single-peak *** the offshore area,open sea,and all marine areas,lightning densities have two maxima per *** magnitude of the daily variation in mean lightning density is the largest over land and the smallest over the open *** lightning density over the Pacific Ocean and adjacent land areas is significantly and positively correlated with *** correlation is the strongest over land and the weakest over the open *** Base Height(CBH)may affect the efficiency of CAPE conversion to *** has a positive effect on lightning activity and has a greater impact on land than on the *** the sea,both CAPE and AOD can contribute to lightning activity,but the magnitudes of the influence of CAPE and AOD on lightning activity remain to be *** activity over land and sea is a result of the combined action of AOD and CAPE.

关键词： Pacific lightning land-sea contrast thermal conditions aerosol

The Numerical Accuracy Analysis of Asymptotic Homogenization Method and Multiscale Finite Element Method for Periodic Composite Materials

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Computer Modeling in Engineering & Sciences 2016年第5期111卷 395-419页

作者： Hao Dong Yufeng Nie Zihao Yang Yang Zhang YataoWu Department of applied mathematics School of ScienceNorthwestern Polytechnical UniversityXi’an 710129PR China Research center for Computational Science Northwestern Polytechnical UniversityXi’an 710129PR China

In this paper,we discuss the numerical accuracy of asymptotic homogenization method(AHM)and multiscale finite element method(MsFEM)for periodic composite *** numerical calculation of the model problems for four kinds of typical periodic composite materials,the main factors to determine the accuracy of first-order AHM and second-order AHM are found,and the physical interpretation of these factors is ***,the way to recover multiscale solutions of first-order AHM and MsFEM is theoretically analyzed,and it is found that first-order AHM and MsFEM provide similar multiscale solutions under some ***,numerical experiments verify that MsFEM is essentially a first-order multiscale method for periodic composite materials.

关键词： Asymptotic homogenization method Multiscale finite element method First-order AHM Slight fluctuations Second-order AHM Severe fluctuations

Statistical Modeling of CMIP5 Projected Changes in Extreme Wet Spells over China in the Late 21st Century

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Journal of Meteorological Research 2017年第4期31卷 678-693页

作者： Lianhua ZHU Yun LI Zhihong JIANG Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science &Technology Nanjing 210044 China School of mathematics and Statistics Nanjing University of Information Science & Technology Nanjing 210044 China Business Intelligence & Data Analytics Western Power WA 6000 Australia

The observed intensity, frequency, and duration（IFD） of summer wet spells, defined here as extreme events with one or more consecutive days in which daily precipitation exceeds a given threshold（the 95th percentile）, and their future changes in RCP4.5 and RCP8.5 in the late 21st century over China, are investigated by using the wet spell model（WSM） and by extending the point process approach to extreme value analysis. Wet spell intensity is modeled by a conditional generalized Pareto distribution, frequency by a Poisson distribution, and duration by a geometric distribution, respectively. The WSM is able to realistically model summer extreme rainfall spells during 1961–2005, as verified with observations at 553 stations throughout China. To minimize the impact of systematic biases over China in the global climate models（GCMs） of the Coupled Model Intercomparison Project Phase 5（CMIP5）, five best GCMs are selected based on their performance to reproduce observed wet spell IFD and average precipitation during the historical period. Furthermore, a quantile–quantile scaling correction procedure is proposed and applied to produce ensemble projections of wet spell IFD and corresponding probability distributions. The results show that in the late 21st century, most of China will experience more extreme rainfall and less low-intensity rainfall. The intensity and frequency of wet spells are projected to increase considerably, while the duration of wet spells will increase but to a much less extent. The IFD changes in RCP8.5 are in general much larger than those in RCP4.5.

关键词： wet spell model extreme value theory bias correction Coupled Model Intercomparison Project Phase 5