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Graphene reinforced nanoarchitectonics of 3D interconnected magnetic-dielectric frameworks for high-efficient and anti-corrosive microwave absorbers

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Journal of Materials Science & Technology 2024年第1期168卷 194-207页

作者： Chenchen liu Xiaofang Feng Shuning liu Guo Lin Zhongxiang bai Lingling Wang Ke Zhu Xiulan Li Xiaobo liu School of Materials and Energy University of Electronic Science and Technology of ChinaChengdu611731China Sichuan Province Engineering Technology Research Center of Novel CN Polymeric Materials Chengdu611731China School of Chemical Engineering Northwest UniversityXi’an710069China Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology School of Environmental Science and EngineeringSun Yat-sen UniversityGuangzhou510275China

The combination of high efficiency and environmental stability is vital to promote the commercial appli-cations of microwave absorption(MA)materials,yet remains challenging in the absence of facile routes.Here,we put forward a graphene-reinforced construct approach for one-pot synthesis of 3D intercon-nected magnetic-dielectric frameworks via pre-functionalization and subsequent assembly.Multiple in-teractions among discrete precursors are capable of manipulating the confined growth and interfacial self-assembly.Significant enhancements in MA properties are triggered in a straightforward manner us-ing ultralow feeding fractions of graphene oxide nanosheet.The minimum reflection loss is up to-60.1 dB(99.9999%wave absorption)and the effective absorption bandwidth reaches 5.9 GHz(almost covering the Ku band).Remarkably,based on the optimization by ultralow concentrations of graphene,the as-prepared nanoarchitecture simultaneously integrates strong absorption,broad bandwidth,and low matching thick-ness.The embedded graphene nanosheets serve as high-speed electron transmission channels and hollow resonance cavities,facilitating multimode attenuations and impedance-matching characteristics.Mean-while,the graphene-reinforced framework suppresses the corrosion of magnetic components,whose cor-rosion rate reduces by an order of magnitude.This study provides a simple procedure to boost magnetic-dielectric absorbers for comprehensive MA performances and enhanced corrosion resistance.

关键词： 3D Magnetic-dielectric framework Graphene nanosheet Microwave absorption Anti-corrosion

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Ytterbium modified birnessite MnO_(2) for improving deep oxidation of toluene

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Journal of Rare Earths 2024年第4期42卷 668-675页

作者： Linjiang Sun Yan cheng Yujie liu Can Yi Faculty of Geosciences and Environmental Engineering Southwest Jiaotong UniversityChengdu611756China

A series of rare earth metals modified birnessite manganese dioxides(RE-Mn)was synthesized by hydrothermal method and their catalytic degradation of toluene was investigated.Yb-Mn shows the best toluene oxidation activity with the conversion of T50%and T99%at 196 and 226℃,respectively.The physiochemical characterizations identified that the high catalytic performance and excellent stability of Yb-Mn are mainly associated with its higher molar ratios of Mn^(4+)/Mn^(3+),more lattice oxygen(Olatt),and better mobility of surface adsorbed oxygen(O_(ads)).Moreover,it is confirmed that introduction of Yb into birnessite MnO_(2) facilitates the production of acetic acid at lower temperature.These results can aid the design of high-efficiency manganese oxide catalysts for the catalytic combustion of VOCs.

关键词： Manganese oxide Rare earth metal doping Toluene Catalytic combustion

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Capillary Property of Entangled Porous Metallic Wire materials and Its Application in Fluid Buffers:Theoretical Analysis and Experimental Study

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Defence Technology（防务技术） 2024年第1期31卷 400-416页

作者： Yu Tang Yiwan Wu Hu cheng Rong liu Engineering Research Center for Metal Rubber School of Mechanical Engineering and AutomationFuzhou UniversityFuzhou 350156China AECC Guizhou Liyang Aviation Power Co. LTDGuiyang 550014China College of Computer and Information Sciences Fujian Agriculture and Forestry UniversityFuzhou 350156China

Strong impact does serious harm to the military industries so it is necessary to choose reasonable cushioning material and design effective buffers to prevent the impact of equipment.Based on the capillary property entangled porous metallic wire materials(EPMWM),this paper designed a composite buffer which uses EPMWM and viscous fluid as cushioning materials under the low-speed impact of the recoil force device of weapon equipment(such as artillery,mortar,etc.).Combined with the capillary model,porosity,hydraulic diameter,maximum pore diameter and pore distribution were used to characterize the pore structure characteristics of EPMWM.The calculation model of the damping force of the composite buffer was established.The low-speed impact test of the composite buffer was conducted.The parameters of the buffer under low-speed impact were identified according to the model,and the nonlinear model of damping force was obtained.The test results show that the composite buffer with EPMWM and viscous fluid can absorb the impact energy from the recoil movement effectively,and provide a new method for the buffer design of weapon equipment(such as artillery,mortar,etc.).

关键词： Entangled porous metallic wire materials Capillary property Viscousfluid Low-speed impact Damping force

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Honeycomb-like biochar framework coupled with Fe_(3)O_(4)/FeS nanoparticles as efficient heterogeneous Fenton catalyst for phenol degradation

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Journal of Environmental Sciences 2024年第2期136卷 390-399页

作者： Aihua cheng Yi He Xiaohe liu Chi He Department of Environmental Engineering College of Geology and EnvironmentXi’an University of Science and TechnologyXi’an 710054China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an 710049China National Engineering Laboratory for VOCs Pollution Control Material and Technology University of Chinese Academy of SciencesBeijing 101408China

Achieving an efficient and stable heterogeneous Fenton reaction over a wide pH range is of great significance for wastewater treatment.Here,a pollen-derived biochar catalyst with a unique honeycomb-like structure,coupled with the dispersion of magnetic Fe_(3)O_(4)/FeS(Fe/S)nanoparticles,was synthesized by simple impregnation precursor,followed by pyrolysis.The prepared Fe/S-biochar catalyst demonstrated outstanding phenol degradation efficiency across a wide pH range,with 98%of which eliminated even under neutral conditions(pH 7.0).The high catalytic activity was due to the multilevel porous structure of pollenderived biochar provided enough active sites and allowed for better electron transfer,then increases oxidation ability to promote the reaction.Moreover,the acid microenvironment formed by SO_(4)^(2-)group from Fe/S composite extended the pH range for Fenton reaction,and S^(2-)facilitated the conversion of≡Fe^(3+)to≡Fe^(2+),resulting in remarkable degradation efficiency.Further,biochar can effectively promote cycling stability by limiting Fe leaching.This work may provide a general strategy for designing 3D framework biochar-based Fe/S catalysts with excellent performance for heterogeneous Fenton reactions.

关键词： Biomass Biochar Fenton reaction Fe_(3)O_(4)/FeS(Fe/S) Phenol degradation

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Single-shot non-line-of-sight imaging based on chromato-axial differential correlography

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Photonics Research 2024年第1期12卷 106-114页

作者： LINGFENG liu SHUO ZHU WENJUN ZHANG LIANFA bai ENLAI GUO JING HAN Jiangsu Key Laboratory of Spectral Imaging and Intelligent Sense Nanjing University of Science and TechnologyNanjing 210094China

Non-line-of-sight(NLOS)imaging is a challenging task aimed at reconstructing objects outside the direct view of the observer.Nevertheless,traditional NLOS imaging methods typically rely on intricate and costly equipment to scan and sample the hidden object.These methods often suffer from restricted imaging resolution and require high system stability.Herein,we propose a single-shot high-resolution NLOS imaging method via chromato-axial differential correlography,which adopts low-cost continuous-wave lasers and a conventional camera.By leveraging the uncorrelated laser speckle patterns along the chromato-axis,this method can reconstruct hidden objects of diverse complexity using only one exposure measurement.The achieved background stability through singleshot acquisition,along with the inherent information redundancy in the chromato-axial differential speckles,enhances the robustness of the system against vibration and colored stain interference.This approach overcomes the limitations of conventional methods by simplifying the sampling process,improving system stability,and achieving enhanced imaging resolution using available equipment.This work serves as a valuable reference for the real-time development and practical implementation of NLOS imaging.

关键词： axial speckle overcome

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On the electric behaviour of conductive grease inside the contact zone

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Friction 2024年第4期12卷 683-697页

作者： Yuxin ZHOU Jinjie liu Xinming LI He CHONG Bo HAN Qinghua bai SKF(Shanghai)Automotive Technologies Co. Ltd.Shanghai 201814China School of Mechanical and Automotive Engineering Qingdao University of TechnologyQingdao 266250China

Conductive grease has been considered as a potential solution in addressing electric erosion issue inside motor bearings.Understanding the conductive grease performance,especially the electric and tribological behaviour is crucial for its application.This paper combines bulk grease characterization and contact film study considering both electrical and tribological loading conditions.The results show that the electric performance for the selected conductive grease sample is electric field dependent,including both frequency and voltage amplitude.Its film impedance inside the contact area is closely related to the external electric field,running condition,and lubrication regime.The following film impedance calculation tells that not only bulk grease electric parameters,but the contact parameter,lubricant film contour and lubrication condition should be considered when performing the overall bearing electrical modelling.

关键词： Electric erosion lubricant conductivity grease film impedance

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Finite barrier bound state

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Light(Science & Applications) 2024年第4期13卷 664-671页

作者： Tao liu Kai bai Yicheng Zhang Duanduan Wan Yun Lai C.T.Chan Meng Xiao Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education and School of Physics and Technology Wuhan University430072 WuhanChina. National Laboratory of Solid State Microstructures School of Physicsand Collaborative Innovation Center of Advanced MicrostructuresNanjing University210093 NanjingChina. Department of Physics The Hong Kong University of Science and TechnologyClear Water BayKowloon999077Hong KongChina. Wuhan Institute of Quantum Technology 430206 WuhanChina

A boundary mode localized on one side of a finite-size lattice can tunnel to the opposite side which results in unwanted couplings.Conventional wisdom tells that the tunneling probability decays exponentially with the size of the system which thus requires many lattice sites before eventually becoming negligibly small.Here we show that the tunneling probability for some boundary modes can apparently vanish at specific wavevectors.Thus,similar to bound states in the continuum,a boundary mode can be completely trapped within very few lattice sites where the bulk bandgap is not even well-defined.More intriguingly,the number of trapped states equals the number of lattice sites along the normal direction of the boundary.We provide two configurations and validate the existence of this peculiar finite barrier-bound state experimentally in a dielectric photonic crystal at microwave frequencies.Our work offers extreme flexibility in tuning the coupling between localized states and channels as well as a new mechanism that facilitates unprecedented manipulation of light.

关键词： boundary state eventually

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A New Method for the Aging Evaluation of Oil-Paper Insulation Using η-Butanol and Methanol

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 717-726页

作者： Jianyi Wang Yuanxiang Zhou Jun liu Zhaowei Wang Song bai Jiayu Lu Department of High Voltage China Electric Power Research InstituteBeijing 100192China State Key Laboratory of Power Grid Environmental Protection Beijing 100192China Electrical Engineering Department Tsinghua UniversityBeijing 100084China Solar Storage Division of State Key Lab of Power System and Generation Equipment School of Electrical EngineeringXinjiang UniversityUrumqi 830047China State Grid Wuwei Electric Power Supply Company Wuwei 733000China

To improve the accuracy and efficiency of the aging life prediction and assessment of transformer oil-paper insulation,and to make up for the deficiencies of traditional characterizers,such as 2-furfural,carbon monoxide,and carbon dioxide,a method for the simultaneous determination of methanol,ethanol,n−propanol,and η-butanol in oil with a single injection is established by headspace-gas chromatography-mass spectrometry.The measured results show that the determination limits of the four alcohol characterizers can be controlled to 10μg/kg level.Based on this method,the change patterns of the above four alcohols with thermal aging time and degree of polymerization are obtained through thermal aging experimental research.Ethanol,η-propanol,and η-butanol in oil indicate nearly linear correlations with thermal aging time and degree of polymerization,similar to that of methanol.By analyzing 52 sets of measured data of 500 kV EHV transformers in operation,η-butanol is found to have excellent performance,and a new method to evaluate the aging state of oil-paper insulation employing η-butanol and methanol is proposed along with the aging attention value model.The measured data of 500 kV EHV transformers in operation indicate that the combination of η-butanol and methanol as the preferred characterizers can effectively compensate for the shortcoming of traditional characterizers in the early stages of aging,and the feasibility of the method is verified.Two possible pathways for the generation of η-butanol by cellulose cleavage during the aging of oil-paper are proposed from the chemical structure of cellulose.

关键词： Aging characterization determination method methanol η-butanol oil-paper insulation 500 kV transformers

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Flow characteristics of radial inflow in impeller rear cavity with baffle plate

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Chinese Journal of Aeronautics 2024年第2期37卷 270-282页

作者： Yang bai Xiang LUO Dongdong liu Zeyu WU Xiaoqiang ZHANG Sipeng WANG Research Institute of Aero-Engine Beihang UniversityBeijing 100191China National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics Beihang UniversityBeijing 100191China School of Energy and Power Engineering Beihang UniversityBeijing 100191China

The research purpose of this paper is to explore the influence of the baffle plate on the airflow in the rear cavity of the centrifugal impeller and optimize the performance of the secondary air system’s air bleed section.In this paper,a comprehensive experimental study was carried out on the flow characteristics in the impeller rear cavity with baffle plate.The windage torque,flow structure and pressure drop between inlet and outlet were measured respectively.The experiment was carried out with the condition that the range of rotational Reynolds number was from 8.33×10^(5)to 22.2×10^(5)and the range of mass flow rate coefficient was from 0.92×10^(4)to 2.92×10^(4).The results show that the static cavity and the narrow stator-rotor cavity formed by the baffle plate effectively suppress the overall swirl coefficient in the cavity.Thus,the static pressure and total pressure drop in the rotor-stator cavity were reduced.The influence of the baffle plate on the windage torque of the rotary disk is related to the turbulence parameters.Under large turbulence parameters,the windage torque would be reduced with baffle plate,while under small turbulence parameters,the baffle plate would increase with baffle plate.In general,the baffle plate can improve the flow capacity and optimize the bleed air performance with proper structure and operation conditions.

关键词： Impeller rear cavity Baffle plate Flow structure Windage torque Pressure drop

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Complementary and alternative medicine on cognitive defects and neuroinflammation after sepsis

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Journal of Traditional Chinese Medicine 2024年第2期44卷 408-416页

作者： LI Zhenxuan WANG Xuerui Luis Ulloa Ayman Youssef bai Yunjing XU Xiaolong liu Qingquan Department of Infectious Diseases Beijing Hospital of Traditional Chinese MedicineCapital Medical UniversityBeijing 100010China Beijing Key Laboratory of Basic Research with Traditional Chinese Medicine on Infectious Diseases Beijing 100010China Infection immunity laboratory Beijing Institute of Traditional Chinese MedicineBeijing 100010China Clinical College of Traditional Chinese Medicine Capital Medical UniversityBeijing 100069China Center for Perioperative Organ Protection Department of AnesthesiologyDuke University Medical CenterDurhamNorth Carolina 27710USA

Sepsis-associated encephalopathy(SAE)is a common manifestation of sepsis,ranging from mild confusion and delirium to severe cognitive impairment and deep coma.SAE is associated with higher mortality and long-term outcomes,particularly substantial declines in cognitive function.The mechanisms of SAE probably include neuroinflammation that is mediated by systemic inflammation and ischemic lesions in the brain,a disrupted blood–brain barrier,oxidative stress,neurotransmitter dysfunction,and severe microglial activation.Increasing evidence suggests that complementary and alternative medicine,especially Traditional Chinese Medicine(TCM),is favorable in alleviating cognitive decline after sepsis.Here,we summarized the studies of traditional herbal remedies,TCM formulas and acupuncture therapy in animal models of neurological dysfunctions after sepsis in recent decades and reviewed their potential mechanisms.

关键词： sepsis-associated encephalopathy cognitive dysfunction complementary therapies neuroinflammatory diseases medicine Chinese traditional review

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