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Boosting Interfacial Polarization Through Heterointerface Engineering in MXene/Graphene Intercalated-Based Microspheres for Electromagnetic Wave Absorption

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Nano-Micro Letters 2023年第9期15卷 436-460页

作者： Ge Wang Changfeng Li Diana Estevez Peng Xu Mengyue Peng Huijie Wei Faxiang Qin Institute for Composites Science Innovation(InCSI) School of Materials Science and EngineeringZhejiang University38 Zheda RoadHangzhou 310027People’s Republic of China Ningbo Institute of Technology Zhejiang University1 Qianhu South RdNingbo 315100People’s Republic of China Foshan(Southern China)Institute for New Materials FoshanPeople’s Republic of China

Multi-layer 2D material assemblies provide a great number of interfaces beneficial for electromagnetic wave absorption.However,avoiding agglomeration and achieving layer-by-layer ordered intercalation remain chal-lenging.Here,3D reduced graphene oxide(rGO)/MXene/TiO_(2)/Fe_(2)C lightweight porous microspheres with periodical intercalated structures and pronounced inter-facial effects were constructed by spray-freeze-drying and microwave irradiation based on the Maxwell–Wagner effect.Such approach reinforced interfacial effects via defects introduction,porous skeleton,multi-layer assembly and multi-compo-nent system,leading to synergistic loss mechanisms.The abundant 2D/2D/0D/0D intercalated heterojunctions in the microspheres provide a high density of polari-zation charges while generating abundant polarization sites,resulting in boosted interfacial polarization,which is verified by CST Microwave Studio simulations.By precisely tuning the 2D nanosheets intercalation in the heterostructures,both the polarization loss and impedance matching improve significantly.At a low filler loading of 5 wt%,the polarization loss rate exceeds 70%,and a minimum reflection loss(RLmin)of-67.4 dB can be achieved.Moreover,radar cross-section simulations further confirm the attenuation ability of the optimized porous microspheres.These results not only provide novel insights into understanding and enhancing interfacial effects,but also constitute an attractive platform for implementing heterointerface engineering based on customized 2D hierarchical architectures.

关键词： MXene Hierarchical microspheres Interfacial polarization Spray-freeze-drying Microwave absorption

Numerical Simulation Investigation on Parameter Optimization of Deep-Sea Mining Vehicles

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Chinese Journal of Mechanical Engineering 2023年第2期36卷 365-377页

作者： Hongyun Wu Wei liu Min Jiang Changfeng Li Jiangming li Bingzheng Chen Chunlai Wang Yuheng Chen Institute of Marine Research Changsha Mining Research Institute Co.Ltd.Changsha 410012China School of Mechanical and Electrical Engineering Central South UniversityChangsha 410083China School of Energy and Engineering China University of Mining&Technology BeijingBeijing 100083China

The four-track walking mining vehicle can better cope with the complex terrain of cobalt-rich crusts on the seabed.To explore the influence of different parameters on the obstacle-crossing ability of mining vehicles,this paper took a certain type of mine vehicle as an example and establish a mechanical model of the mine vehicle.Through this model,the vehicle's traction coefficient variation could be analyzed during the obstacle-crossing process.It also reflected the relationship between the obstacle-crossing ability and the required traction coefficient.Many parameters were used for this analysis including the radius of the guide wheel radius,ground clearance of the driving wheel,the dip angle of the approaching angular and the position of centroid.The result showed that the ability to cross the obstacles requires adhesion coefficient as support.When the ratio between obstacle height and ground clearance of the guide wheel was greater than 0.7,the required adhesion coefficient increased sharply.The ability to cross obstacles will decrease,if the radius of the guide wheel increases,the height of the driving wheel increases or the dip angle of the approaching angular increases.It was most beneficial to cross the obstacle when-the ratio of the distance between the center of mass and the front driving wheel to the wheelbase is between 0.450.48.The results of this paper could provide reference for structural parameter design and performance research for mining vehicles.

关键词： Rich crusts Four-track vehicles Triangular track Obstacle-crossing

An Upwind Mixed Volume Element-Fractional Step Method on a Changing Mesh for Compressible Contamination Treatment from Nuclear Waste

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Advances in Applied Mathematics and Mechanics 2018年第6期10卷 1384-1417页

作者： Changfeng Li Yirang Yuan Huailing Song Institute of Mathematics Shandong UniversityJinan 250100China School of Economics Shandong UniversityJinan 250100China College of Mathematics and Econometrics Hunan UniversityChangsha 410082China

In this paper the authors discuss the numerical simulation problem of threedimensional compressible contamination treatment from nuclear waste.The mathematical model is defined by an initial-boundary nonlinear convection-diffusion system of four partial differential equations:a parabolic equation for the pressure,two convection-diffusion equations for the concentrations of brine and radionuclide and a heat conduction equation for the temperature.The pressure appears within the concentration equations and heat conduction equation,and the Darcy velocity controls the concentrations and the temperature.The pressure is solved by the conservative mixed volume element method,and the order of the accuracy is improved by the Darcy velocity.The concentration of brine and temperature are computed by the upwind mixed volume element method on a changing mesh,where the diffusion is discretized by a mixed volume element and the convection is treated by an upwind scheme.The composite method can solve the convection-dominated diffusion problems well because it eliminates numerical dispersion and nonphysical oscillation and has high order computational accuracy.The mixed volume element has the local conservation of mass and energy,and it can obtain the brine and temperature and their adjoint vector functions simultaneously.The conservation nature plays an important role in numerical simulation of underground fluid.The concentrations of radionuclide factors are solved by the method of upwind fractional step difference and the computational work is decreased by decomposing a three-dimensional problem into three successive one-dimensional problems and using the method of speedup.By the theory and technique of a priori estimates of differential equations,we derive an optimal order result in L^(2) norm.Numerical examples are given to show the effectiveness and practicability and the composite method is testified as a powerful tool to solve the well-known actual problem.

关键词： Compressible nuclear waste contamination in porous media upwind mixed volume element-fractional step on a changing mesh conservation of mass and energy convergence analysis numerical example

Completion of R^(2)with a Conformal Metric as a Closed Surface

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Analysis in Theory and Applications 2021年第1期37卷 59-73页

作者： changfeng Gui Qinfeng li Department of Mathematics The University of Texas at San AntonioSan AntonioTexas 78249USA School of Mathematics Hunan UniversityChangshaHunan 410082China

In this paper,we obtain some asy mptotic behav ior results for solutions to the prescribed Gaussian curvature equation.Moreover,we prove that under a con-formal metric in R^(2),if the total Gaussian curvature is 4π,the conformal area of R^(2)is finite and the Gaussian curvature is bounded,then R^(2)is a compact C^(l,α)surface after completion at∞,for anya∈(0,1).If the Gaussian curvature has a Holder decay at in-finity,then the completed surface is C^(2).For radial solutions,the same regularity holds if the Gaussian curvature has a limit at infinity.

关键词： Gaussian curvature conformal geometry semilinear equations entire solutions

An overview of autophagy in the differentiation of dental stem cells

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BIOCELL 2024年第1期48卷 47-64页

作者： XITONG ZHAO TIANJUAN JU XINWEI li Changfeng LiU LULU WANG li-AN WU State Key Laboratory of Oral&Maxillofacial Reconstruction and Regeneration National Clinical Research Center for Oral DiseasesShaanxi Clinical Research Center for Oral DiseasesDepartment of Pediatric DentistrySchool of StomatologyThe Fourth Military Medical UniversityXi’an710032China

Dental stem cells(DSCs)have attracted significant interest as autologous stem cells since they are easily accessible and give a minimal immune response.These properties and their ability to both maintain self-renewal and undergo multi-lineage differentiation establish them as key players in regenerative medicine.While many regulatory factors determine the differentiation trajectory of DSCs,prior research has predominantly been based on genetic,epigenetic,and molecular aspects.Recent evidence suggests that DSC differentiation can also be influenced by autophagy,a highly conserved cellular process responsible for maintaining cellular and tissue homeostasis under various stress conditions.This comprehensive review endeavors to elucidate the intricate regulatory mechanism and relationship between autophagy and DSC differentiation.To achieve this goal,we dissect the intricacies of autophagy and its mechanisms.Subsequently,we elucidate its pivotal roles in impacting DSC differentiation,including osteo/odontogenic,neurogenic,and angiogenic trajectories.Furthermore,we reveal the regulatory factors that govern autophagy in DSC lineage commitment,including scaffold materials,pharmaceutical cues,and the extrinsic milieu.The implications of this review are far-reaching,underpinning the potential to wield autophagy as a regulatory tool to expedite DSC-directed differentiation and thereby promote the application of DSCs within the realm of regenerative medicine.

关键词： Dental stem cells Cell differentiation Autophagy Mitophagy Autophagy regulation

Identification and Expression Profile of a Neuropeptide LFRFamide-like Gene During Different Stages of Gonadal Development in the Cephalopod Sepia pharaonis

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Journal of Ocean University of China 2024年第2期23卷 499-508页

作者： QIU Jiayin SUN lianlian li Shuang ZHOU Xu CHI changfeng ZHENG libing National and Provincial Joint Engineering Research Center for Marine Germplasm Resources Exploration and Utilization School of Marine Science and TechnologyZhejiang Ocean UniversityZhoushan 316022China

Neuropeptides are widely distributed in vertebrates and invertebrates,regulating a variety of physiological activities in the organisms,such as metabolism,feeding and reproduction.In this study,to explore the function of neuropeptide LFRFamide in Sepia pharaonis,the full-length cDNA of LFRFamide-like gene(named SpLFRFL,MG869822.1)was identified with rapid amplification of cDNA ends(RACE)method.The sequence of SpLFRFL was 860 bp in length and encoded 188 amino acids containing 4 different mature peptides:1 copy of PHTPFRFamide,NSLFRFamide,TIFRFamide,and 3 copies of GNLFRFamide.Multiple alignment and phylogenetic analysis results showed that SpLFRFL shared high identity with LFRFamides of Sepia officinalis and Sepiella japonica and had the closest relationship with them.Through quantitative Real-time PCR(qRT-PCR),it was found that the SpLFRFL gene was highly expressed in the optic lobe and brain at three different stages during gonad development in both genders.Moreover,the four mature peptides at a concentration of 0.01μmol L^(−1) could inhibit the protein synthesis in the Chinese hamster ovary cell strain-K1(CHOK1)induced by SpGnRH.These data suggest that SpLFRFL might be involved in the development and reproduction of S.pharaonis.The results can contribute to future studies on neuropeptide evolution and function and benefit the cuttlefish farming.

关键词： neuropeptide LFRFamide-like cephalopod cuttlefish Sepia pharaonis development reproduction

Theory and application of numerical simulation method of capillary force enhanced oil production

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Applied Mathematics and Mechanics(English Edition) 2015年第3期36卷 379-400页

作者： Yirang YUAN Aijie CHENG Danping YANG Changfeng Li Yunxin liU Institute of Mathematics Shandong University

A kind of second-order implicit upwind fractional step finite difference methods are presented for the numerical simulation of coupled systems for enhanced （chemical） oil production with capillary force in the porous media. Some techniques, e.g., the calculus of variations, the energy analysis method, the commutativity of the products of difference operators, the decomposition of high-order difference operators, and the theory of a priori estimate, are introduced. An optimal order error estimate in the l2 norm is derived. The method is successfully used in the numerical simulation of the enhanced oil production in actual oilfields. The simulation results are satisfactory and interesting.

关键词： enhanced （chemical） oil production system on consideration ference optimal order l2 capillary force second-order three-dimensional porous coupled implicit upwind fractional step difestimate application in actual oilfield

Synthesis of Cu-Doped Layered Transition Metal Oxide Cathode Materials Directly from Metal-Organic Frameworks for Sodium-Ion Batteries

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Chinese Journal of Chemistry 2023年第20期41卷 2597-2603页

作者： Xiaoniu Hou Changfeng Li Mengjie li Yuansheng liu Wei Zhu Zhenfei li Yunhua Xu School of Materials Science and Engineering Key Laboratory of Advanced Ceramics and Machining Technology(Ministry of Education)and Tianjin Key Laboratory of Composite and Functional MaterialsTianjin UniversityTianjin300072 China

Mn-based layered transition metal oxides are promising cathode materials for sodium-ion batteries(SIBs)because of their high theoretical capacities,abundant raw materials,and environment-friendly advantages.However,they often show insufficient performance due to intrinsic issues including poor structural stability and dissolution of Mn^(3+).Atomic doping is an effective way to address these structural degradation issues.Herein,we reported a new synthesis strategy of a Cu-doped layered cathode by directly calcinating a pure metal-organic framework.Benefiting from the unique structure of MOF with atomic-level Cu doping,a homogeneous Cu-doped layered compound P2-Na_(0.674)Cu_(0.01)Mn_(0.99)O_(2) was obtained.The Cu substitution promotes the crystal structural stability and suppresses the dissolution of Mn,thus preventing the structure degradation of the layered cathode materials.A remarkably enhanced cyclability is realized for the Cu-doped cathode compared with that without Cu doping,with 83.8%capacity retention after 300 cycles at 100 mA·g^(-1).Our findings provide new insights into the design of atomic-level doping layered cathode materials constructed by MOFs for high-performance SIBs.

关键词： Metal-organic frameworks Synthesis design/Sodium-ion batteries Layered cathode materials Atomic doping

Prokaryotic diversity and community composition in the surface sediments of the Changjiang River Estuary in summer

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Acta Oceanologica Sinica 2023年第9期42卷 113-124页

作者： changfeng Qu Xixi Wang liping Zhang Huamao Yuan Xuegang li Ning li Fushan Chen Jinlai Miao Key Laboratory of Marine Eco-Environmental Science and Technology First Institute of OceanographyMinistry of Natural ResourcesQingdao 266061China CAS Key Laboratory of Marine Ecology and Environmental Sciences Institute of OceanologyChinese Academy of SciencesQingdao 266071China College of Chemistry and Molecular Engineering Qingdao University of Science and TechnologyQingdao 266042China Marine Natural Products R&D Laboratory Qingdao Key LaboratoryQingdao 266061China

Microorganisms are fundamental for the functioning of marine ecosystems and are involved in the decomposition of organic matter, transformation of nutrients and circulation of biologically-important chemicals. Based on the complexity of the natural geographic characteristics of the Changjiang River Estuary, the geographic distribution of sedimentary microorganisms and the causes of this distribution are largely unexplored. In this work, the surface sediment samples from the adjacent sea area of the Changjiang River Estuary were collected. Their prokaryotic diversity was examined by high-throughput sequencing technology, and the environmental factors of the bacterial community were investigated. The results indicated that the distribution of prokaryotic communities in the sediments of the study areas showed obvious spatial heterogeneity. The sampling sequences divided the sample regions into three distinct clusters. Each geographic region had a unique community structure, although Proteobacteria, Bacteroidota, Desulfobacterota, Acidobacteriota, and Actinobacteriota all existed in these three branches. Canonical correspondence analysis demonstrated that prokaryotic diversity and community distribution were significantly correlated with the geographic location of sediment, seawater depth, and in particular, nutrient content(e.g., total phosphorus, total organic carbon and dissolved oxygen). Moreover, it was found for the first time that the metal ions obviously affected the composition and distribution of the prokaryotic community in this area. In general, this work provides new insights into the structural characteristics and driving factors of prokaryotic communities under the background of the ever-changing Changjiang River Estuary.

关键词： prokaryotic diversity 16S rRNA gene geophysicochemical factors high-throughput sequencing(HTS) Changjiang River Estuary