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高综合性能电卡复合材料及大功率制冷器件

太阳能学报 2024年第7期45卷 420-426页

作者：李强杜飞宏冯嘉旺施骏业陈江平钱小石上海交通大学机械与振动国家重点实验室制冷与低温工程研究所上海200240 上海交通大学江苏中关村研究院溧阳213300

通过制备BaZr_(0.2)Ti_(0.8)O_(3)-P(VDF-TrFE-CFE)复合材料来改善聚合物基电卡材料的综合性能,设计基于流固耦合传热的大功率制冷器件并通过有限元仿真来评估以不同电卡材料为制冷核心元件的器件制冷能力和效率。结果表明:相较于基础... 详细信息

通过制备BaZr_(0.2)Ti_(0.8)O_(3)-P(VDF-TrFE-CFE)复合材料来改善聚合物基电卡材料的综合性能,设计基于流固耦合传热的大功率制冷器件并通过有限元仿真来评估以不同电卡材料为制冷核心元件的器件制冷能力和效率。结果表明:相较于基础聚合物,BZT质量分数为10%的复合材料T-BZT-10%具有显著优异的电卡制冷性能和导热性能。在10 K的温度跨度下,以T-BZT-10%为制冷核心元件的电卡器件可实现31.0 W/cm^(3)的制冷功率密度和1060.4 W的总制冷功率为基础电卡制冷器件的10倍),且COP达到5.2。

关键词：复合材料数值仿真导热系数电卡效应制冷器件

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Multi-element B-site substituted perovskite ferroelectrics exhibit enhanced electrocaloric effect

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Science China(Technological Sciences) 2023年第4期66卷 1119-1128页

作者： du feihong SONG ZhiWu XU YuTao HAN DongLin LI Qiang ZHENG ShanYu SHEN JiaHe QIAN XiaoShi Interdisciplinary Research Centre School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Zhejiang Research Institute of Chemical Industry Hangzhou 310023China

Electrocaloric(EC)refrigeration holds the promise to achieve next-generation refrigeration technology that can be efficiently powered by ***_(3)(BT)-based ferroelectric materials are attractive owing to their environmentally benign compositions,large polarization,and existing manufacturing method for multilayer ceramic capacitors(MLCC),which have stimulated intensive research efforts on these ***,we report an enhanced electrocaloric effect(ECE)and the refrigeration capacity of multi-element B-site substituted BT-based *** compositions of the proposed Ba(Hf_(x)Sn_(x)Zr_(y))-Ti_(1-2x-y)O_(3)(BHSZT)ceramics were selected by fine-tuning each substituent against Titanium ions Ti^(4+),aiming to their respective morphotropic phase boundary(MPB).The BHSZT exhibited an ECE that is greater than that of the single-element substituted BaTiO_(3) ceramics by at least 50%,reaching an adiabatic temperature change of above 1.7 K under 40 kV/***,the operating temperature window of the BHSZT ceramics is observed to cover the room temperature,which is a critical feature that allows the device implementation in our daily *** multi-element substitution improved the overall ECE performances,providing a high degree of freedom for polar reorientation and hence the large polar entropy that could be utilized by the external electric field.

关键词： ferroelectrics electrocalorics Ceramics

Polymeric nanocomposites for electrocaloric refrigeration

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能源前沿:英文版 2023年第4期17卷 450-462页

作者： Yu CAI Qiang LI feihong du Jiawang FENG Donglin HAN Shanyu ZHENG Shihao YANG Yingjing ZHANG Binbin YU Junye SHI Xiaoshi QIAN State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai200240China Interdisciplinary Research Center Institute of Refrigeration and CryogenicsSchool of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai200240China Shanghai Jiao Tong University Zhongguancun Research Institute Liyang213300China

Electrocaloric refrigeration represents an alternative solid-state cooling technology that has the potential to reach the ultimate goal of achieving zero-global-warming potential,highly efficient refrigeration,and heat *** date,both polymeric and inorganic oxides have demonstrated giant electrocaloric effect as well as respective cooling *** both polymeric and inorganic oxides have been identified as promising cooling methods that are distinguishable from the traditional ones,they still pose many challenges to more practical *** an electrocaloric material point of view,electrocaloric nanocomposites may provide a solution to combine the beneficial effects of both organic and inorganic electrocaloric *** article reviews the recent advancements in polymer-based electrocaloric composites and the state-of-the-art cooling devices operating these *** a device point of view,it discusses the existing challenges and potential opportunities of electrocaloric nanocomposites.

关键词： nanocomposites electrocaloric refrigeration polymer

Isotopic characteristics and source analysis of atmospheric ammonia during agricultural periods in the Xichuan area of the Danjiangkou Reservoir

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Journal of Environmental Sciences 2024年第2期136卷 460-469页

作者： Xiaoshu Chen Tongqian Zhao Chunyan Xiao Xiaoming Guo feihong Chen Institute of Resources and Environment Henan Polytechnic UniversityJiaozuo 454000China

Nitrogen deposition is an important means of exogenous nitrogen input in reservoir *** activities around the reservoir lead to a sharp increase in the concentration of ammonia in the atmosphere,which poses a threat to the reservoir water *** the contribution of agricultural ammonia release to atmospheric NH_(x)(gaseous NH_(3)and particulate NH_(4)^(+)),in the reservoir area can provide a theoretical foundation for local reactive nitrogen *** collected atmospheric NH_(3)and NH_(4)^(+)samples during the agricultural periods and analyzed the isotopic characteristics of atmospheric NH_(x)and the contribution rates of different ammonia sources in the Xichuan area of the Danjiangkou *** results showed that the initialδ~(15)N values of NH_(3)(-30.0‰to–7.2‰)and particulate NH_(4)^(+)(–33‰to+4.9‰for finer and coarser particles,respectively)are different,and their contribution ratios from dissimilar ammonia sources are also different,among which NH_(4)^(+)is more susceptible to meteorological ***,since the atmospheric NH_(x)in the Xichuan area is mainly gaseous NH_(3),the final sources of atmospheric ammonia nitrogen source depend on gaseous NH_(3).Agricultural sources(59%-74%)were the main NH_(3)sources in this *** them,the fertilizer use emission was dominant;it had the highest contribution rate in summer during the agricultural period and a more prominent impact in areas with less human *** regulation of the application of high-ammonia releasing fertilizer,especially during the agricultural period in summer,is an effective way to reduce the threat of atmospheric ammonia to water health.

关键词： Danjiangkou reservoir Atmospheric ammonia nitrogen Isotope Ammonia source analysis Agricultural sources

A low-profile metamaterial absorber with ultrawideband reflectionless and wide-angular stability

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Defence Technology（防务技术） 2024年第4期34卷 258-268页

作者： feihong Lin Zhongming Yan Ping Wang Yu Wang Hongcheng Zhou Haoran Lu School of Electrical Engineering Southwest Jiaotong UniversityChengdu 611756China Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle Ministry of EducationChengdu 610031China China Academy of Launch Vehicle Technology Beijing 100076China

An ultrawideband reflectionless metamaterial absorber(MA)is proposed by replacing the metallic ground with the complementary split-ring resonator(CSRR)*** proposed MA exhibits-10 d B reflectivity spectrum from 1 GHz to 20 GHz,which maintains more than 90%absorption from 1.5 GHz to20 ***,it achieves angle stability for TE and TM polarization at oblique incident angles up to 40°and 65°,*** achieve broadband absorption spectrum,we have adopted a single-layer high-impedance surface(HIS)loaded with a double-layer magnetic material(MM)*** further realize the RCS reduction into a lower frequency range,we have employed the scattering cancellation technology into the traditional metallic ***,we have fabricated a sample exhibiting the 10 d B RCS reduction from 1 GHz to 20 GHz with a thickness of 10 *** and simulation results confirm that the proposed MA exhibits excellent comprehensive performance,making it suitable for many practical applications.

关键词： Metamaterial absorber(MA) Magnetic material(MM) High-impedance surface(HIS) Scattering cancellation technology Ultrawideband Wide-angular stable

Traceless photodegradable polymer cocoons for universal protein delivery and light-controlled gene editing

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Science China Chemistry 2024年第2期67卷 664-676页

作者： Huaibin Yu Meron Tsegay Kifle Lili Chen feihong Xiong Yan Zhang Shangbang Gao Wei Hou Shuliang Chen Weining Zhao Yuzhou Wu Hubei Engineering Research Center for Biomaterials and Medical Protective Materials Hubei Key Laboratory of Bioinorganic Chemistry&Materia MedicaKey Laboratory of Material Chemistry for Energy Conversion and StorageMinistry of EducationSchool of Chemistry and Chemical EngineeringHuazhong University of Science and Technology(HUST)Wuhan430074China Zhengzhou Research Institute Harbin Institute of TechnologyZhengzhou450000China College of Life Science and Technology Huazhong University of Science and Technology(HUST)Wuhan430074China Institute of Medical Virology School of Basic Medical SciencesWuhan UniversityWuhan430071China College of Pharmacy Shenzhen Technology UniversityShenzhen518118China

Polymer conjugation was found highly valuable in clinic to improve the bioavailability of protein ***,it is still a tremendous challenge to achieve a complete release of original proteins from the conjugated hybrid under external stimulus to recover active proteins in the targeted ***,we report a general light-controlled protein delivery methodology by weaving a photodegradable polymer cocoon around proteins,which could reliably protect them from degradation in the dark while efficiently releasing them under illumination without any residual *** surface charge of the polymer shell is easily tunable to facilitate efficient cell *** versatility of this strategy is demonstrated by the delivery of the Cas9/sg RNA complex that realized light-controlled gene editing both in vitro and in vivo,and such repertoire is of particular value in regard to minimizing the off-target toxicity of CRISPR-Cas9-based gene therapy.

关键词： photodegradable polymer-protein conjugate protein delivery light control gene editing

A Practical Regular LDPC Coded Scheme for Physical-Layer Information Security

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China Communications 2024年第5期21卷 190-201页

作者： du Junyi CETC Key Laboratory of Avionic Information System Southwest China Institute of Electronic TechnologyChengdu 610036China

In this paper,we aim to design a practical low complexity low-density parity-check(LDPC)coded scheme to build a secure open channel and protect information from *** this end,we first propose a punctured LDPC coded scheme,where the information bits in a codeword are punctured and only the parity check bits are transmitted to the *** further propose a notion of check node type distribution and derive multi-edge type extrinsic information transfer functions to estimate the security performance,instead of the well-known weak metric bit error *** optimize the check node type distribution in terms of the signal-to-noise ratio(SNR)gap and modify the progressive edge growth algorithm to design finite-length *** results show that our proposed scheme can achieve a lower computational complexity and a smaller security gap,compared to the existing scrambling and puncturing schemes.

关键词： extrinsic information transfer function physical layer scheme secure open channel security gap

Transformer and GAN-Based Super-Resolution Reconstruction Network for Medical Images

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Tsinghua Science and Technology 2024年第1期29卷 197-206页

作者： Weizhi du Shihao Tian Arts&Sciences College Washington University in St.LouisSt.LouisMO 63130USA Department of Electric and Computing Engineering Cornell UniversityIthacaNY 14850USA

Super-resolution reconstruction in medical imaging has become more demanding due to the necessity of obtaining high-quality images with minimal radiation dose,such as in low-field magnetic resonance imaging(MRI).However,image super-resolution reconstruction remains a difficult task because of the complexity and high textual requirements for diagnosis *** this paper,we offer a deep learning based strategy for reconstructing medical images from low resolutions utilizing Transformer and generative adversarial networks(T-GANs).The integrated system can extract more precise texture information and focus more on important locations through global image matching after successfully inserting Transformer into the generative adversarial network for picture ***,we weighted the combination of content loss,adversarial loss,and adversarial feature loss as the final multi-task loss function during the training of our proposed model *** comparison to established measures like peak signal-to-noise ratio(PSNR)and structural similarity index measure(SSIM),our suggested T-GAN achieves optimal performance and recovers more texture features in super-resolution reconstruction of MRI scanned images of the knees and belly.

关键词： super-resolution image reconstruction Transformer generative adversarial network(GAN)

High-pressure minerals and new lunar mineral changesite-(Y) in Chang’e-5 regolith

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Matter and Radiation at Extremes 2024年第2期9卷 90-97页

作者： Jing Yang Wei du Center for Lunar and Planetary Sciences Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China State Key Laboratory of Ore Deposit Geochemistry Institute of GeochemistryChinese Academy of Sciences(CAS)Guiyang 550081China CAS Center for Excellence in Comparative Planetology Hefei 230026China

Forty-five years after the Apollo and Luna missions, China’s Chang’e-5 (CE-5) mission collected ∼1.73 kg of new lunar materials from one ofthe youngest basalt units on the Moon. The CE-5 lunar samples provide opportunities to address some key scientific questions related to theMoon, including the discovery of high-pressure silica polymorphs (seifertite and stishovite) and a new lunar mineral, changesite-(Y). Seifertitewas found to be coexist with stishovite in a silica fragment from CE-5 lunar regolith. This is the first confirmed seifertite in returned lunarsamples. Seifertite has two space group symmetries (Pnc2 and Pbcn) and formed from an α-cristobalite-like phase during “cold” compressionduring a shock event. The aftershock heating process changes some seifertite to stishovite. Thus, this silica fragment records different stagesof an impact process, and the peak shock pressure is estimated to be ∼11 to 40 GPa, which is much lower than the pressure condition forcoexistence of seifertite and stishovite on the phase diagram. Changesite-(Y), with ideal formula (Ca_(8)Y)◻Fe^(2+)(PO_(4))_(7) (where ◻ denotes avacancy) is the first new lunar mineral to be discovered in CE-5 regolith samples. This newly identified phosphate mineral is in the form ofcolumnar crystals and was found in CE-5 basalt fragments. It contains high concentrations of Y and rare earth elements (REE), reaching upto ∼14 wt. % (Y,REE)2O3. The occurrence of changesite-(Y) marks the late-stage fractional crystallization processes of CE-5 basalts combinedwith silicate liquid immiscibility. These new findings demonstrate the significance of studies on high-pressure minerals in lunar materials andthe special nature of lunar magmatic evolution.

关键词： evolution minerals basalt