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Fe-N-C core-shell catalysts with single low-spin Fe(Ⅱ)-N_(4)species for oxygen reduction reaction and high-performance proton exchange membrane fuel cells

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Journal of Energy Chemistry 2024年第6期93卷 538-546,I0013页

作者： Yan Wan Linhui yu Bingxin yang Caihong Li Chen Fang Wei Guo Fang-Xing Xiao yangming Lin Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth MaterialsHaixi InstituteChinese Academy of SciencesXiamen 361021FujianChina CAS Key Laboratory of Urban Pollutant Conversion Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021FujianChina Fujian Institute of Research on the Structure of Matter Chinese Academy of SciencesFuzhou 350002FujianChina College of Materials Science and Engineering Fuzhou UniversityNew CampusMinhou 350108FujianChina College of Chemistry and Materials Science Fujian Normal UniversityFuzhou 350117FujianChina

Fe-N-doped carbon materials(Fe-N-C)are promising candidates for oxygen reduction reaction(ORR)relative to Pt-based catalysts in proton exchange membrane fuel cells(PEMFCs).However,the intrinsic contributions of Fe-N_(4)moiety with different chemical/spin states(e.g.d1,d2,d3)to ORR are unclear since various states coexist *** the present work,Fe-N-C core-shell nanocatalyst with single lowspin Fe(Ⅱ)-N_(4)species(d1)is synthesized and identified with ex-situ ultralow temperature Mossbauer spectroscopy(T=1.6 K)that could essentially differentiate various Fe-N_(4)states and invisible Fe-O *** quantifying with CO-pulse chemisorption,site density and turnover frequency of Fe-N-C catalysts reach 2.4×10^(-9)site g^(-1)and 23 e site~(-1)s^(-1)during the ORR,***-wave potential(0.915V_(RHE))of the Fe-N-C catalyst is more positive(approximately 54 mV)than that of Pt/***,we observe that the performance of PEMFCs on Fe-N-C almost achieves the 2025 target of the US department of Energy by demonstrating a current density of 1.037 A cm^(-2)combined with the peak power density of 0,685 W cm^(-2),suggesting the critical role of Fe(Ⅱ)-N_(4)site(d1).After 500 h of running,PEMFCs still deliver a power density of 1.26 W cm^(-2)at 1.0 bar H_(2)-O_(2),An unexpected rate-determining step is figured out by isotopic labelling experiment and theoretical *** work not only offers valuable insights regarding the intrinsic contribution of Fe-N_(4)with a single spin state to alkaline/acidic ORR,but also provides great opportunities for developing high-performance stable PEMFCs.

关键词： Fuel cells Oxygen reduction reaction Non-platinum group metals(PGMs) Isotopic labelling Active site TOF

Side-Chain-Type Polyimide-Cu Complexes with Suppressed Activation Energy of Relaxation for Advanced High-Temperature Capacitor

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Chinese Journal of Polymer Science 2024年第8期42卷 1038-1048页

作者： Bai-yang Zhou Ze-Tong Ma Shi-Long Zhong Zhen-Jie Huang Qi Guo deng-Chong Feng Zhong-Ke yuan Shao-Lin Lu yu-Zhao yang Cheng Wang ding-Shan yu Xu-dong Chen Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education Guangdong Engineering Technology Research Centre for High Performance Organic and Polymer Photoelectric Functional FilmsSchool of ChemistrySun Yat-sen UniversityGuangzhou 510275China School of Chemical Engineering and Light Industry Guangdong University of TechnologyGuangzhou 510006China Guangdong Provincial Laboratory of Chemistry and Fine Chemical Industry Jieyang Centre Jieyang 515200China Chemistry and Chemical Engineering Guangdong Laboratory Shantou 515031China

The burgeoning growth of the new energy vehicles and aviation industry has escalated the need for energy storage capacitors capable of stable operation in harsh *** advent of metal-polyimide complexes has illuminated a novel approach for preparing tem perature-resistant ***,the general application of these metal-polyimide com plexes is impeded by the high dielectric loss and low breakdown strength,consequences of main-chain coordination and excessive metal ions ***,our study proposes a novel polyimideCu complex material(POP-Cu)predicated on side-chain-type pyridine-Cu coordination,utilizing the structural backbone PMdA-OdA of mature commercial PI(Kapton)with reliable *** to the high degree of freedom afforded by the side chain with suppressed relaxation activation energy and the long-range electron delocalization formed by d-πcoordination,the dielectric constant of this material containing merely 2.7 mol%Cu increases from 3.25(POPI)to 5.58,while maintaining a remarkably low dielectric loss of ***,this material exhibits a substantial dC breakdown strength of 436.2 MV·m^(-1)and a high energy density of 5.42 J·cm^(-3),coupled with superior mechanical and thermal *** at 150℃,it retains over 90%of its room-temperature energy density,demon strating notable dielectric stability under high *** attributes underscore its promising application for capacitors operating in harsh environments.

关键词： dielectric performance Polyimide complexes Side-Chain-Type High-temperature capacitor

Sensitivity impacts owing to the variations in the type of zero-range pairing forces on the fission properties using the density functional theory

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Nuclear Science and Techniques 2024年第3期35卷 198-207页

作者： yang Su Ze-yu Li Li-Le Liu Guo-Xiang dong Xiao-Bao Wang Yong-Jing Chen China Nuclear data Center China Institute of Atomic EnergyBeijing 102413China School of Science Huzhou UniversityHuzhou 313000China

Using the Skyrme density functional theory,potential energy surfaces of^(240)Pu with constraints on the axial quadrupole and octupole deformations(q_(20)and q_(30))were *** volume-like and surface-like pairing forces,as well as a combination of these two forces,were used for the Hartree–Fock–Bogoliubov *** in the least-energy fission path,fission barrier,pairing energy,total kinetic energy,scission line,and mass distribution of the fission fragments based on the different forms of the pairing forces were analyzed and *** fission dynamics were studied based on the timedependent generator coordinate method plus the Gaussian overlap *** results demonstrated a sensitivity of the mass and charge distributions of the fission fragments on the form of the pairing *** on the investigation of the neutron-induced fission of^(239)Pu,among the volume,mixed,and surface pairing forces,the mixed pairing force presented a good reproduction of the experimental data.

关键词： Nuclear fission density functional theory Pairing force Potential energy surfaces Fission fragment distribution

Biomimetic microchannel network with functional endothelium formed by sacrificial electrospun fibers inside 3d gelatin methacryloyl(GelMA)hydrogel models

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第1期25卷 79-96页

作者： Haoyu SUN Haiyang MA Li WANG yang LIU Tian HOU Wenjie TANG Qing yu Meiwen AN Meiling WEN Institute of Biomedical Engineering College of Biomedical EngineeringTaiyuan University of TechnologyTaiyuan030024China

Three-dimensional(3d)hydrogel models play a crucial role in tissue engineering for promoting tissue regeneration.A biomimetic microchannel network system in the 3d hydrogel model is necessary for optimal cellular *** report describes the preparation of a biomimetic hydrogel scaffold with an internal microchannel network,using electrospinning techniques and the sacrificial template method for 3d cell *** and cavities were created within the gelatin methacryloyl(GelMA)hydrogel by sacrificing polyvinyl alcohol(PVA)electrospun fibers(>10µm),resulting in the creation of microvessel-like *** characterizations,swelling properties,and biodegradation analysis were conducted to investigate the feasibility of a biomimetic microchannel network hydrogel scaffold for 3d cell culture *** to pure GelMA hydrogel,the hydrogel with microchannels promoted cell proliferation,adhesion,and endothelial tube ***,the results confirmed that the biomimetic microchannel network scaffold had a major impact on the distribution and arrangement of human umbilical vein endothelial cells(HUVECs)and can enable the formation of artificial microvasculature by the culture of HUVECs and cell media perfusion.

关键词： Biomimetic scaffold Photocrosslinking Microchannel network Tissue engineering Artificial microvascular

Novel C_(sf)/SiBCN composites prepared by densifying C_(sf)/MA-SiBCN with the PIP process:Oxidation behavior and damage mechanism

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Journal of Advanced Ceramics 2024年第5期13卷 666-678页

作者： Wenhao dou daxin Li Bingzhu Wang Zhihua yang Jun Chen dechang Jia Ralf Riedel yu Zhou Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China Key Laboratory of Advanced Structural-Functional Integration Materials and Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China Chongqing Research Institute of HIT Chongqing 401135China Beijing Institute of Control Engineering Beijing 100094China Institut für Materialwissenschaft Technische Universität DarmstadtDarmstadt D-64287Germany School of Materials Science and Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China

To improve the oxidation resistance of short carbon fiber(C_(sf))-reinforced mechanically alloyed SiBCN(MA-SiBCN)(C_(sf)/MA-SiBCN)composites,dense amorphous C_(sf)/SiBCN composites containing both MA-SiBCN and polymer-derived ceramics SiBCN(PdCs-SiBCN)were prepared by repeated polymer infiltration and pyrolysis(PIP)of layered C_(sf)/MA-SiBCN composites at 1100℃,and the oxidation behavior and damage mechanism of the as-prepared C_(sf)/SiBCN at 1300–1600℃ were compared and discussed with those of C_(sf)/*** C_(sf)/MA-SiBCN composites resist oxidation attack up to 1400℃ but fail at 1500℃ due to the collapse of the porous framework,while the PIP-densified C_(sf)/SiBCN composites are resistant to static air up to 1600℃.during oxidation,oxygen diffuses through preexisting pores and the pores left by oxidation of carbon fibers and pyrolytic carbon(PyC)to the interior of the *** to the oxidative coupling effect of the MA-SiBCN and PdCs-SiBCN matrices,a relatively continuous and dense oxide layer is formed on the sample surface,and the interfacial region between the oxide layer and the matrix of the as-prepared composite contains an amorphous glassy structure mainly consisting of Si and O and an incompletely oxidized but partially crystallized matrix,which is primarily responsible for improving the oxidation resistance.

关键词： mechanically alloyed SiBCN(MA-SiBCN) polymer-derived ceramics SiBCN(PdCs-SiBCN) short carbon fiber-reinforced SiBCN(C_(sf)/SiBCN)composites polymer infiltration and pyrolysis(PIP) oxidation damage mechanism

A bifunctional nitrile additive for high-performance lithiumoxygen batteries

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Nano Research 2024年第7期17卷 6119-6126页

作者： Ziwei Li yue yu dongyue yang Jin Wang Junmin Yan Gang Huang Tong Liu Xinbo Zhang Key Laboratory of Automobile Materials Ministry of EducationDepartment of Materials Science and EngineeringJilin UniversityChangchun 130022China State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China department of Chemistry and Waterloo Institute for Nanotechnology University of Waterloo200 University Ave.W.WaterlooOntario N2L 3G1Canada School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei 230026China

Li-O_(2)batteries with high energy density hold significant promise as next-generation energy storage ***,Li-O_(2)batteries have poor cycling performance at high current densities and large capacities,primarily due to the high impedance caused by the instability of the lithium anode and the sluggish kinetics in the discharge products decomposition on the ***,we investigated a bifunctional nitrile additive(2-methoxy benzonitrile(2-MBN))with good chemical/electrochemical stability to improve the performances of Li-O_(2)*** 2-MBN could actively modify the anode by ensuring uniform Li+deposition and optimizing the composition of solid electrolyte interphase(SEI).Meanwhile,it could also facilitate the decomposition of discharge products by inducing the formation of sheet-like Li_(2)O_(2),significantly reducing the battery charge *** bifunctional effects of 2-MBN for the anode and cathode enable Li-O_(2)batteries to achieve a stable lifetime of 97 cycles at a current density of 600 mA·g^(−1)with a fixed capacity of 2000 mAh·g^(−1),much better than that of Li-O_(2)batteries without 2-MBN(28 cycles).The inclusion of 2-MBN provides an effective approach for attaining high-performance Li-O_(2)batteries.

关键词： nitrile additives Li-O_(2)batteries lithium metal anode charge overpotential

A comprehensive analysis of dAC-SdC FPGA low power object detection challenge

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Science China(Information Sciences) 2024年第8期67卷 300-320页

作者： Jingwei ZHANG Guoqing LI Meng ZHANG Xinye CAO yu ZHANG Xiang LI Ziyang CHEN Jun yang School of Electronics Science and Engineering Southeast University

The lower power object detection challenge(LPOdC) at the IEEE/ACM design Automation Conference is a premier contest in low-power object detection and algorithm(software)-hardware co-design for edge artificial intelligence, which has been a success in the past five years. LPOdC focused on designing and implementing novel algorithms on the edge platform for object detection in images taken from unmanned aerial vehicles(UAVs), which attracted hundreds of teams from dozens of countries to participate. Our team SEUer has been participating in this competition for three consecutive years from 2020 to 2022 and obtained sixth place respectively in 2020 and 2021. Recently, we achieved the championship in 2022. In this paper, we presented the LPOdC for UAV object detection from 2018 to 2022, including the dataset, hardware platform,and evaluation method. In addition, we also introduced and discussed the details of methods proposed by each year's top three teams from 2018 to 2022 in terms of network, accuracy, quantization method, hardware performance, and total score. Additionally, we conducted an in-depth analysis of the selected entries and results, along with summarizing representative methodologies. This analysis serves as a valuable practical resource for researchers and engineers in deploying the UAV application on edge platforms and enhancing its feasibility and reliability. According to the analysis and discussion, it becomes evident that the adoption of a hardware-algorithm co-design approach is paramount in the context of tiny machine learning(TinyML).This approach surpasses the mere optimization of software and hardware as separate entities, proving to be essential for achieving optimal performance and efficiency in TinyML applications.

关键词： tiny machine learning object detection convolutional neural networks algorithm-hardware co-design low power field programmable gate array

Understanding the spatial interaction of ultrasounds based on three-dimensional dual-frequency ultrasonic field numerical simulation

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China Foundry 2024年第1期21卷 29-43页

作者： Zhao-yang Yin Qi-chi Le Yan-chao Jiang da-zhi Zhao Qi-yu Liao Qi Zou Key Lab of Electromagnetic Processing of Materials Ministry of EducationNortheastern UniversityShenyang 110819China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China

A transient 3d model was established to investigate the effect of spatial interaction of ultrasounds on the dual-frequency ultrasonic field in magnesium alloy *** effects of insertion depth and tip shape of the ultrasonic rods,input pressures and their ratio on the acoustic field distribution were discussed in ***,the spacing,angle,and insertion depth of two ultrasonic rods significantly affect the interaction between distinct *** a result,various acoustic pressure distributions and cavitation regions are *** spherical rods mitigate the longitudinal and transversal attenuation of acoustic pressure and expand the cavitation volume by 53.7%and 31.7%,respectively,compared to the plate and conical *** the input pressure will enlarge the cavitation region but has no effect on the acoustic pressure distribution *** acoustic pressure ratio significantly affects the pressure distribution and the cavitation region,and the best cavitation effect is obtained at the ratio of 2:1(P15:P20).

关键词： dual-frequency ultrasonic numerical model acoustic pressure spatial interaction magnesium alloy

The AMPK and AKT/GSK3β pathways are involved in recombinant proteins fibroblast growth factor 1(rFGF1 and rFGF1a) improving glycolipid metabolism in rainbow trout(Oncorhynchus mykiss) fed a high carbohydrate diet

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Animal Nutrition 2024年第2期17卷 11-24页

作者： Huixia yu Shuo Geng Shuai Li Yingwei Wang Xin Ren debin Zhong Haolin Mo Mingxing Yao Jiajia yu yang Li Lixin Wang College of Animal Science and Technology Northwest A&F University Meixian Aquaculture Farm of Shitouhe Reservoir Administration

Fibroblast growth factor 1(FGF1) regulates vertebrate cell growth, proliferation and differentiation, and energy metabolism. In this study, we cloned rainbow trout(Oncorhynchus mykiss) fgf1 and fgf1a, prepared their recombinant proteins(rFGF1 and rFGF1a), and described the molecular mechanisms by which they improve glycolipid metabolism in carnivorous fish. A 31-d feeding trial was conducted to investigate whether they could enhance glycolipid metabolism in rainbow trout on high-carbohydrate diets(HCd). A total of 720 rainbow trout(8.9 ± 0.5 g) were equally divided into 4 groups: the chow diet(Cd) group injected with PBS, the HCd group injected with PBS, the HCd group injected with rFGF1(400 ng/g body weight), and the HCd group injected with rFGF1a(400 ng/g body weight). The results showed that short-term HCd had a significant positive effect on the specific growth rate(SGR) of rainbow trout(P d to an increase in crude fat, serum triglyceride(TG) and glucose content, as well as serum glutamic pyruvic transaminase(GPT) and glutamic oxalacetic transaminase(GOT) contents(P d. Nevertheless, rFGF1 and rFGF1a showed beneficial therapeutic effects. They significantly reduced the crude fat content of the liver, serum TG, GOT, and GPT contents caused by HCd(P d acc2 m RNAs implied the promotion of TG catabolism. Moreover, rFGF1 and rFGF1a contributed to promoting lipolysis by activating the AMPK pathway and reducing lipid accumulation in the liver caused by HCd. In addition,the rFGF1 and r FGF1a-treated groups significantly reduced serum glucose levels and elevated hepatic glycogen content under HCd, and increased glucose uptake by hepatocytes. We observed a decrease in mRNA levels for pepck, g6pase, and pygl, along with an increase in mRNA levels for gys, glut2, and gk in the liver. Furthermore, these proteins regulated hepatic gluconeogenesis and glycogen synt

关键词： Rainbow trout Recombinant proteins Fibroblast growth factor 1 Glycogen synthesis Lipid deposition