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Recent Progress in Fabrication and Structural Design of Thermal Conductive Polymer Composites

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Chinese Journal of Polymer Science 2024年第3期42卷 277-291,I0004页

作者： Yuan-Kai Du zheng-Xue Shi Shan Dong Hui jin Xue Ke Pei Zhao Bing-Bing Jiang Feng you Hubei Key Laboratory of Plasma Chemistry and Advanced Materials School of Material Science and EngineeringWuhan Institute of TechnologyWuhan 430205China Key Laboratory of Green Preparation and Application of Functional Materials Ministry of EducationHubei UniversityWuhan 430062China Institute of Molecular Aggregation Science Tianjin UniversityTianjin 300072China

In recent years, the demand direction for electronic equipment has expanded into embedded and miniaturized devices. The heat radiation problem has become one of the most significant factors for hindering the development of electronic devices. Since heat radiation material is one of the important components in electronic devices, the demand for enhancing thermal conductivity is also increasingly urgent. Research on thermal conductive polymer composites has become a major direction for developing functional composites. This work reviewed the recent progress in the fabrication of thermal conductive polymer composites. Five different structures are presented, including the using of single fillers,hybrid fillers, double threshold percolation structure, segregated structure and other complex multiphase structures. Specifically, the preparation of high-performance thermal conductive polymer composites was introduced through the combination of various thermal conductive fillers.Finally, the development direction of high thermal conductive polymer composites was briefly explored.

关键词： Thermal conductive polymer Hybrid fillers Polymer composite Thermal resistance

Liquid lens based holographic camera for real 3D scene hologram acquisition using end-to-end physical model-driven network

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Light(Science & Applications) 2024年第3期13卷 488-497页

作者： Di Wang Zhao-Song Li Yi zheng you-Ran Zhao Chao Liu jin-Bo Xu Yi-Wei zheng Qian Huang Chen-Liang Chang Da-Wei Zhang Song-Lin Zhuang Qiong-Hua Wang School of Instrumentation and Optoelectronic Engineering Beihang UniversityBeijing 100191China School of Optical-Electrical and Computer Engineering University of Shanghai for Science and TechnologyShanghai 200093China

With the development of artificial intelligence,neural network provides unique opportunities for holography,such as high fidelity and dynamic calculation.How to obtain real 3D scene and generate high fidelity hologram in real time is an urgent problem.Here,we propose a liquid lens based holographic camera for real 3D scene hologram acquisition using an end-to-end physical model-driven network(EEPMD-Net).As the core component of the liquid camera,the first 10 mm large aperture electrowetting-based liquid lens is proposed by using specially fabricated solution.The design of the liquid camera ensures that the multi-layers of the real 3D scene can be obtained quickly and with great imaging performance.The EEPMD-Net takes the information of real 3D scene as the input,and uses two new structures of encoder and decoder networks to realize low-noise phase generation.By comparing the intensity information between the reconstructed image after depth fusion and the target scene,the composite loss function is constructed for phase optimization,and the high-fidelity training of hologram with true depth of the 3D scene is realized for the first time.The holographic camera achieves the high-fidelity and fast generation of the hologram of the real 3D scene,and the reconstructed experiment proves that the holographic image has the advantage of low noise.The proposed holographic camera is unique and can be used in 3D display,measurement,encryption and other fields.

关键词： calculation solution holographic

A self-centering and stiffness-controlled MEMS accelerometer

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Microsystems & Nanoengineering 2024年第1期10卷 27-40页

作者： Yiming jin Zhipeng Ma Ziyi Ye Mingkang Li Xudong zheng Zhonghe jin School of Aeronautics and Astronautics Zhejiang UniversityHangzhou 310013China Key Laboratory of Micro/Nano-Satellite Research of Zhejiang Province Hangzhou 310007PR China

This paper presents a high-performance MEMS accelerometer with a DC/AC electrostatic stiffness tuning capability based on double-sided parallel plates(DSPPs).DC and AC electrostatic tuning enable the adjustment of the effective stiffness and the calibration of the geometric offset of the proof mass,respectively.A dynamical model of the proposed accelerometer was developed considering both DC/AC electrostatic tuning and the temperature effect.Based on the dynamical model,a self-centering closed loop is proposed for pulling the reference position of the forceto-rebalance(FTR)to the geometric center of DSPP.The self-centering accelerometer operates at the optimal reference position by eliminating the temperature drift of the readout circuit and nulling the net electrostatic tuning forces.The stiffness closed-loop is also incorporated to prevent the pull-in instability of the tuned low-stiffness accelerometer under a dramatic temperature variation.Real-time adjustments of the reference position and the DC tuning voltage are utilized to compensate for the residue temperature drift of the proposed accelerometer.As a result,a novel controlling approach composed of a self-centering closed loop,stiffness-closed loop,and temperature drift compensation is achieved for the accelerometer,realizing a temperature drift coefficient(TDC)of approximately 7μg/℃ and an Allan bias instability of less than 1μg.

关键词： stiffness electrostatic centering

A Quick Calculation Method for Radiation Pattern of Submillimeter Telescope with Deformation and Displacement

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Research in Astronomy and Astrophysics 2024年第3期24卷 249-265页

作者： Jia you Yi-Wei Yao zheng Wang School of Automation Southeast UniversityNanjing 210096China

Radiation pattern captures the electromagnetic performance of reflector antennas,which is significantly affected by the deformation of the primary reflector due to gravity and the displacement of the secondary reflector.During the design process of large reflector antennas,a substantial amount of time is often dedicated to iteratively adjusting structural parameters and validating electromagnetic performance.To improve the efficiency of the design process,we first propose an approximate calculation method of optical path difference(OPD)for the deformation of the primary reflector under gravity and the displacement of the secondary reflector.Then an OPD fitting function based on the modified Zernike polynomials is proposed to capture the phase difference of radiation over the aperture plane,based on which the radiation pattern will be obtained quickly by the aperture field integration method.Numerical experiments demonstrate the effectiveness of the proposed quick calculation method for analyzing the radiation pattern of a 10.4 m submillimeter telescope antenna at its highest operating frequency of 856 GHz.In comparison with the numerical simulation method based on GRASP(which is an antenna electromagnetic analysis tool combining physical optics(PO)and physical theory of diffraction(PTD)),the quick calculation method reduces the time for radiation pattern analysis from more than one hour to less than two minutes.Furthermore,the quick calculation method exhibits excellent accuracy for the figure of merit(FOM)of the radiation pattern.Therefore,the proposed quick calculation method can obtain the radiation pattern with high speed and accuracy.Compared to the time-consuming numerical simulation method(PO and PTD),it can be employed for quick analysis of the radiation pattern for the lateral displacement of the secondary reflector and the deformation of the primary reflector under gravity in the design process of a reflector antenna.

关键词： instrumentation high angular resolution-methods data analysis-methods analytical

Clinical observation on 90 cases of primary dysmenorrhea treated by buccal acupuncture therapy:a randomized controlled study

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Journal of Traditional Chinese Medicine 2024年第1期44卷 172-181页

作者： YANG Yi YE Huijun zheng Huiling jin Lihua Department of Obstetrics and Gynecology the Second Affiliated Hospital of Zhejiang Chinese Medical UniversityXinhua Hospital of Zhejiang ProvinceHangzhou 310005China

OBJECTIVE:To explore the short-term and long-term efficacy of buccal acupuncture therapy in the treatment of patients with primary dysmenorrhea(PD).METHODS:A total of 90 patients with PD who were admitted to the Second Affiliated Hospital of Zhejiang University of Traditional Chinese Medicine from January 2020 to December 2021 were included in this study and randomly divided into three groups,including the observation group,the control group,and the placebo group,with 30 patients in each group.Patients in the observation group were treated according to the syndrome types of Traditional Chinese Medicine,those in the control group were treated with Saridon,and those in the placebo group received a placebo.The visual analog scale(VAS)scores of these patients were evaluated at different time points(before treatment,5 min after needle retention,30 min after needle retention,1 h after treatment,2 h after treatment,1 d after treatment,and 2 d after treatment).The Cox Menstrual Symptom Scale(CMSS)scores were assessed before the treatment and after three courses of treatment.Besides,these two scales were also evaluated during follow-up.Moreover,the pain score and adverse reactions of these patients were assessed during treatment.RESULTS:After treatment,the VAS and CMSS scores in the observation group decreased significantly(P<0.05)5 and 30 min after needle retention and after treatment.CONCLUSION:Buccal acupuncture therapy is verified to have short-term efficacy in the treatment of PD.In addition,this therapy has an immediate analgesic effect and long-term efficacy in reducing the severity and frequency of PD.

关键词： buccal acupuncture therapy primary dysmenorrhea pain score randomized controlled trial

Copper-Free Resin-Based Braking Materials:A New Approach for Substituting Copper with Fly-Ash Cenospheres in Composites

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 401-412页

作者： Kaikui zheng youxi Lin Shanmin you Zhiying Ren Jianmeng Huang School of Mechanical Engineering and Automation Fuzhou UniversityFuzhou 350108China National United Engineering Laboratory for Advanced Bearing Tribology Henan University of Science and TechnologyLuoyang 471023China

Copper particles emitted from braking have become a significant source of environmental pollution.However,copper plays a crucial role in resin-based braking materials.Developing high-performance braking materials without copper has become a significant challenge.In this paper,the resin-based braking materials were filled with flyash cenospheres to develop copper-free braking materials.The effects of fly-ash cenospheres on the physical properties,mechanical and friction and wear properties of braking materials were studied.Furthermore,the wear mechanism of copper-free resin-based braking materials filled with fly-ash cenospheres was discussed.The results indicate that the inclusion of fly-ash cenospheres in the braking materials improved their thermal stability,hardness and impact strength,reduced their density,effectively increased the friction coefficient at medium and high temperatures,and enhanced the heat-fade resistance of the braking materials.The inclusion of fly-ash cenospheres contributed to the formation of surface friction film during the friction process of the braking materials,and facilitated the transition of form from abrasive wear to adhesive wear.At 100-350℃,the friction coefficient of the optimal formulation is in the range of 0.57-0.61,and the wear rate is in the range(0.29-0.65)×10^(-7) cm^(3)·N^(-1)·m^(-1),demonstrating excellent resistance to heat-fade and stability in friction coefficient.This research proposes the use of fly-ash cenospheres as a substitute for environmentally harmful and expensive copper in brake materials,which not only improves the performance of braking materials but also reduces their costs.

关键词： Fly-ash cenospheres Braking materials Friction and wear Heat-fade resistance Wear form

Effective peroxydisulfate activation by CQDs-MnFe_(2)O_(4)@ZIF-8 catalyst for complementary degradation of bisphenol A by free radicals and non-radical pathways

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Chinese Chemical Letters 2024年第5期35卷 371-379页

作者： Shuo Li Xinran Liu Yongjie zheng Jun Ma Shijie you Heshan zheng College of Chemistry and Chemical Engineering Qiqihar UniversityQiqihar 161006China State Key Laboratory of Urban Water Resource and Environment School of EnvironmentHarbin Institute of TechnologyHarbin 150090China

The present study reported fabrication of novel carbon quantum dots-MnFe_(2)O_(4)@ZIF-8(CQDs-MFO@ZIF-8)by using co-precipitation hydrothermal method for activation of peroxydisulfate(PDS)to degrade bisphenol A(BPA),one of important emerging organic pollutants in water environment.CQDs-MFO@ZIF-8 served as a highly efficient thermal activated PDS catalyst with high catalytic degradation efficiency,reusability and stability.The catalyst achieved almost completely removal of 20.0 mg/L BPA within 5.0 min,and the degradation efficiency remained higher than 83%after 5 consecutive cycles.Free radicals(^(·)OH,SO_(4)^(·-)and^(·)O_(2)^(-))and non-free radicals((1)O_(2))were generated in the thermal PDS-activation system,in which singlet oxygen((1)O_(2))played a dominant role in the degradation of BPA.The potential toxicity of BPA degradation intermediates was analyzed upon the culture of E.coli and Chlorella sorokiniana by using Ecological Structure-Activity Relationship Model(ECOSAR)program.The catalytic performances of BPA degradation by CQDs-MFO@ZIF-8 were evaluated for treatment of different practical water samples to further verify the feasibility of practical applications.This study provides proof-in-concept demonstration of new nanomaterials for enhanced catalytic water decontamination.

关键词： Bisphenol A Degradation Peroxydisulfate ^(1)O_(2) Toxicity analysis

Chiral thermally activated delayed fluorescence materials for circularly polarized organic light-emitting diodes

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Science China Chemistry 2024年第4期67卷 1097-1116页

作者： Li Yuan Yi-Pin Zhang you-Xuan zheng State Key Laboratory of Coordination Chemistry Collaborative Innovation Center of Advanced MicrostructuresJiangsu Key Laboratory of Advanced Organic MaterialsSchool of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China

Chirality is an important natural characteristic of organic molecules,and chiral organic molecules have shown extensive application in areas such as pharmaceutical development and material science.Benefiting from the ability to achieve circularly polarized luminescence(CPL),chiral luminescent materials have shown potential applications in anti-glare display,optical communication and,3D display,etc.Due to the ability to harvest both singlet and triplet excitons by a fast reverse intersystem crossing process without involving noble metals,chiral thermally activated delayed fluorescence(TADF)materials with point chirality,axial chirality,planar chirality and helical chirality are regarded as the state-of-the-art materials for circularly polarized organic light-emitting diodes(CP-OLEDs).In recent years,the chiral TADF materials and CP-OLEDs have rapidly developed,but unfortunately,the dissymmetry factors(g)are far from the requirement of practical applications.The ideal emitters and devices should have both high efficiency and a g factor,or at least a balance between these two elements.This review gives an overview of recent progress in chiral TADF materials,with a particular focus on the chiral skeleton,CPL property and device performance.Furthermore,the molecular design concept,device structure and methods to improve the g factors of chiral materials and CP-OLEDs are also discussed.

关键词： chiral thermally activated delayed fluorescence material chiral skeleton circularly polarized luminescence circularly polarized organic light-emitting diodes dissymmetry factor

Paraffin–CaCl_(2)·6H_(2)O dosage effects on the strength and heat transfer characteristics of cemented tailings backfill

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International Journal of Minerals,Metallurgy and Materials 2024年第1期31卷 60-70页

作者： Hai Li Aibing jin Shuaijun Chen Yiqing Zhao you Ju Key Laboratory of Ministry of Education for Efficient Mining and Safety of Metal Mine University of Science and Technology BeijingBeijing 100083China School of Civil and Resources Engineering University of Science and Technology BeijingBeijing 100083China

The challenge of high temperatures in deep mining remains harmful to the health of workers and their production efficiency The addition of phase change materials (PCMs) to filling slurry and the use of the cold storage function of these materials to reduce downhole temperatures is an effective approach to alleviate the aforementioned problem.Paraffin–CaCl_(2)·6H_(2)O composite PCM was prepared in the laboratory.The composition,phase change latent heat,thermal conductivity,and cemented tailing backfill (CTB) compressive strength of the new material were studied.The heat transfer characteristics and endothermic effect of the PCM were simulated using Fluent software.The results showed the following:(1) The new paraffin–CaCl_(2)·6H_(2)O composite PCM improved the thermal conductivity of native paraffin while avoiding the water solubility of CaCl_(2)·6H_(2)O.(2) The calculation formula of the thermal conductivity of CaCl_(2)·6H_(2)O combined with paraffin was deduced,and the reasons were explained in principle.(3) The“enthalpy–mass scale model”was applied to calculate the phase change latent heat of nonreactive composite PCMs.(4)The addition of the paraffin–CaCl_(2)·6H_(2)O composite PCM reduced the CTB strength but increased its heat absorption capacity.This research can give a theoretical foundation for the use of heat storage backfill in green mines.

关键词： paraffin–CaCl_(2)·6H_(2)O heat transfer simulation heat calculation phase change material-based backfill latent heat of formula