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Luminescence of samarium doped hydroxyapatite containing strontium:Effects of doping concentration

Journal of Rare Earths 2022年第3期40卷 398-405,I0002页

作者： Pu Chen Fen Wang Yinpo Qiao Zhen Zhang Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic Materials School of Materials Science and EngineeringShaanxi University of Science and TechnologyXi'an 710021China

A series of samarium(Sm)doped hydroxyapatites containing strontium(Sr)with controllable and adjustable luminescence were designed and prepared via chemical hydrolysis co-precipitation method.The effects of doping concentration of Sm on the structure,composition,photoluminescence(PL),energy transfer,substitute site,fluoresce lifetime and luminescence color of samples were investigated.It is shown that the introduction of Sr ions induces the structure and composition change for Sm doped samples.The typical transitions of Sm^(3+) at 564,601,648 and 707 nm due to^(4)G_(5/2)→^(6)H_(J/2)(J=5,7,9 and 11)transition under the excitation of 404 nm were detected.The PL intensity is affected by the Sr/Ca ratio and Sm concentration,and the optimal concentration of Sm is 0.8 mol%when Sr/Ca ratio equals 7/3.The non-radiative transitions and energy transfer of Sm ions are the main reason for the quenching,and the interactions among ions are ascribed to dipole-dipole type by theoretical calculation.Besides,the ratio of PL intensity between 601 and 648 nm(r_(O/R)=I_(601nm)/I_(648nm))indicates the symmetry and substitution process of Sm ions to Ca/Sr ions.The fluorescence lifetime(τ)decreases with the concentration of Sm increasing,which is the result of the decrease of distance and the enhanced interaction between Sm ions.The CIE chromaticity coordinates and luminescence color of samples are in the orange-red region and have close relation with the concentration of Sm.Furthermore,the cytotoxicity evaluation and confocal laser scanning microscopy(CLSM)observation of samples via cells indicate the good biocompatibility and safe use of this kind of bio-based luminescent materials for their potential efficient fluorescence labeling and detection.

关键词： Samarium Strontium Hydroxyapatite Photo-luminescence Energy transfer Cytotoxicity evaluation

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Synergistic effects of dodecane-castor oil acid mixture on the flotation responses of low-rank coal:A combined simulation and experimental study

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International Journal of Mining Science and Technology 2023年第5期33卷 649-658页

作者： fen Xu Shiwei wang Rongjie Kong Chengyong wang College of Environmental and Chemical Engineering Dalian UniversityDalian 116622China School of Mines and Mechanical Engineering Liupanshui Normal UniversityLiupanshui 553004China

The utilization of an appropriate collector or surfactant is crucial for the beneficiation of low-rank coal.However,in previous studies,the selection of surfactants was primarily based on flotation procedures,which hinders the understanding of the interaction mechanism between surfactant groups and oxygen-containing functional groups at the surface of low-rank coal.In this study,we investigate the flotation of low-rank coal in the presence of a composite collector by using a combined theoretical and experimental approach.The maximum flotation mass recovery achieved was 82.89%using a 3:1 mixture of dodecane and castor oil acid.Fourier-transform infrared and X-ray photoelectron spectroscopic analyses showed that castor oil acid was effectively adsorbed onto the surface of low-rank coal,enhancing the hydrophobicity of the coal.In addition,the diffusion coefficient of water molecules in the water-composite collector-coal system was greater than that in the dodecane system.Moreover,due to the presence of castor oil acid in the flotation process,the adsorption distance of dodecane and low-rank coal became shorter.Molecular dynamics simulations revealed that the diffusion and interaction of surfactant molecules at the interface of low-rank coal particles and water was enhanced because the adsorption of the dodecane-castor oil acid mixture is primarily controlled by hydrogen bonds and electrostatic attraction.Based on these results,a better surfactant for flotation of low-rank coal is also proposed.

关键词： Low-rank coal Flotation Castor oil acid Surface hydrophobicity Molecular dynamics simulation

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Precipitation behaviors and mechanical properties of a solution-treated Mg-Gd-Nd-Zn-Zr alloy during equal-channel angular pressing process

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Journal of Magnesium and Alloys 2022年第1期10卷 257-266页

作者： Zhenzhen Gui Fen Wang Junyi Zhang Dexin Chen Zhixin Kang School of Mechanical and Electrical Engineering Guangzhou University230 Wai Huan Xi RoadGuangzhou Higher Education Mega CenterGuangzhou 510006China Guangdong Key Laboratory for Advanced Metallic Materials Processing School of Mechanical and Automotive EngineeringSouth China University of TechnologyGuangzhou 510640China Institute of Advanced Wear&Corrosion Resistant and Functional Materials Jinan University601 Hmmgpu Avenue WestGuangzhou 510632China

A magnesium alloy processed by equal-channel angular pressing (ECAP) exhibited excellent microstructure refinement and improved strength and hardness.The comprehensive mechanical properties of magnesium alloys have supported the expansion of their applications in the automotive,aerospace,and biomedical industries.Herein,pre-treatment of a solution-treated Mg-2.9Gd-1.5Nd-0.3Zn-0.3Zr alloy was conducted to investigate the precipitate behavior and microstructure evolution during the ECAP process.β;phase grains quickly precipitated from the solution-treated alloy,which accelerated grain refinement and enhanced the ductility after the ECAP process,as compared to the as-cast alloy reported in our previous study.Moreover,spherical precipitates (~200 nm) and fine phases (~100 nm) precipitated along the stripe-like Zn;Zr;phase,which formed a kabap-like structure dispersing homogeneously in the solution-treated alloy during the ECAP process.Owing to grain refinement,dislocations,sphericalβ;precipitates,and texture evolution,the solution-treated alloy after eight passes of ECAP exhibited good comprehensive mechanical properties,with the ultimate tensile strength,yield strength,and elongation values reaching210.9 MPa,263.9 MPa,and 27.9%,respectively.

关键词： Mg-Gd-Nd-Zn-Zr alloy Precipitations Solid solution ECAP Mechanical properties

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Interconnected Ni(OH)_(2)and polyether amine on carbon fiber surface for simultaneously improving interfacial adhesion of epoxy composites and electrochemical properties

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Chinese Journal of Aeronautics 2022年第5期35卷 419-428页

作者： Qing WU Qinqin WAN Qianli LIU Fen Wang Xin LIU Jianfeng ZHU School of Materials Science and Engineering Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic MaterialsShaanxi University of Science&TechnologyXi’an 710021China Shanghai Composites Science&Technology Co. Ltd.Shanghai 201112China

Interconnected Ni(OH)_(2)nanoflakes and polyether amine(PEA)were deposited on carbon fiber tows via a facial and effective process of chemical bath deposition and dip coating.Based on this,a win–win benefit of simultaneously improvements in interfacial shear strength(IFSS)of carbon fiber/epoxy composites and the electrochemical activity has been achieved.Compared with CF and CF-Ni(OH)_(2)composites,the IFSS of CF-Ni(OH)_(2)-PEA/epoxy composite respectively increased 7.9%and 45.4%,which was put down to the covalent bonding of Ni(OH)_(2)-PEA coating with fiber and epoxy matrix,as well as the effective stress transfer by the uniform honeycomb structure of Ni(OH)_(2).In aqueous KOH electrolyte,the CF-Ni(OH)_(2)-PEA electrode presented the maximum specific capacitance of 689.98 F·g^(-1)at 5 m V·s^(-1),572.28 F·g^(-1)at a current density of 0.5 A·g^(-1)due to the strong adhesion of carbon fiber with Ni(OH)_(2)by PEA,the reservation of the threedimensional hollow honeycomb structure of Ni(OH)_(2)for easy ion-transport and–NH_(2)functional groups from PEA for providing more active sites.The excellent performance of CF-Ni(OH)_(2)-PEA reinforcement demonstrates its promising potential for application in high performance composites with integrated structure and function,which shows great advantages in various fields of aerospace,energy,electronics,automobile,civil engineering,sports,etc.

关键词： Carbon fiber Electrochemical properties Interface/interphase Polymer-matrix composites Surface modification

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Recent Progress in Improving Rate Performance of Cellulose-Derived Carbon Materials for Sodium-Ion Batteries

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NANO-MICRO LETTERS 2024年第1期16卷 1-46页

作者： wang, Fujuan Zhang, Tianyun Zhang, Tian He, Tianqi Ran, fen Lanzhou Univ Technol State Key Lab Adv Proc & Recycling Nonferrous Met Lanzhou 730050 Peoples R China Lanzhou Univ Technol Sch Mat Sci & Engn Lanzhou 730050 Peoples R China Lanzhou Univ Technol Sch Mech & Elect Engn Lanzhou 730050 Peoples R China

Enhancing rate performance of cellulose-derived hard carbon anodes from the view of cellulose molecular, crystalline, and aggregation structure is explored.Relationship of storage sodium and rate performance according to theoretical calculation and characterization analysis is illustrated.Cellulose intrinsic microstructure, conversion relationship between the allotropes of cellulose, and the critical influences on cellulose-derived carbon structure are discussed. Cellulose-derived carbon is regarded as one of the most promising candidates for high-performance anode materials in sodium-ion batteries; however, its poor rate performance at higher current density remains a challenge to achieve high power density sodium-ion batteries. The present review comprehensively elucidates the structural characteristics of cellulose-based materials and cellulose-derived carbon materials, explores the limitations in enhancing rate performance arising from ion diffusion and electronic transfer at the level of cellulose-derived carbon materials, and proposes corresponding strategies to improve rate performance targeted at various precursors of cellulose-based materials. This review also presents an update on recent progress in cellulose-based materials and cellulose-derived carbon materials, with particular focuses on their molecular, crystalline, and aggregation structures. Furthermore, the relationship between storage sodium and rate performance the carbon materials is elucidated through theoretical calculations and characterization analyses. Finally, future perspectives regarding challenges and opportunities in the research field of cellulose-derived carbon anodes are briefly highlighted.

关键词： Cellulose Hard carbon Anode materials Rate performance Sodium-ion batteries ELECTROCHEMICAL ENERGY-STORAGE INITIAL COULOMBIC EFFICIENCY 3D INTERCONNECTED NITROGEN HARD-CARBON ANODE MATERIALS BACTERIAL CELLULOSE DOPED CARBON CATHODE MATERIALS HIGH-CAPACITY DOUBLE-LAYER

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Area Operators on Bergman Spaces

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Acta Mathematica Sinica,English Series 2024年第5期40卷 1161-1176页

作者： Xiao fen LV Jordi PAU Mao Fa wang Department of Mathematics Huzhou UniversityHuzhou 313000P.R.China Departament de Matemàtiques i Informàtica Universitat de Barcelona08007 BarcelonaCataloniaSpain School of Mathematics and Statistics Wuhan UniversityWuhan 430072P.R.China

We completely characterize the boundedness of area operators from the Bergman spaces A_(α)^(p)(Bn)to the Lebesgue spaces L^(q)(S_(n))for all 0 详细信息

We completely characterize the boundedness of area operators from the Bergman spaces A_(α)^(p)(Bn)to the Lebesgue spaces L^(q)(S_(n))for all 0

关键词： Area operator Bergman space tent space area formula

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ZIF-8 modified by isocyanate as a photocatalytic antibacterial agent

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Rare Metals 2024年第6期43卷 2708-2718页

作者： Yi-Ning Zhang Zhen Pei Zi-Hao wang Chong-En wang fen-fen Liang Li-Qiao Wei College of Architecture Taiyuan University of Technology Key Laboratory of Interface Science and Engineering in Advanced Materials of Taiyuan University of Technology Ministry of Education Department of Materials Science and Engineering Shanxi Institute of Technology Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering

Zeolite imidazole skeleton(ZIF-8) is a promising option for self-cleaning of building exterior walls due to its large specific surface area,high antibacterial activity and low biotoxicity.However,it suffers from low antibacterial efficiency and yield under visible light irradiation.To address the issues,we developed the photocatalytic materials T-ZIF-8-TDI(thermally treated-ZIF-8-toluene 2,4-diisocyanate) by modifying ZIF-8 with thermal oxygen sensitization and chemical bonding.The results show that the yield of T-ZIF-8-TDI photocatalytic antibacterial agent is increased to 11.5 times of that of T-ZIF-8,while maintaining the crystal structure of T-ZIF-8 and thermal stability up to 60℃.Furthermore,T-ZIF-8-TDI exhibits extended optical response range to the nearinfrared region,significantly narrowed band gap,improved photogenerated elec tron-hole separation efficiency,reduced recombination rate,and excellent photocatalytic performance.When the concentration of antibacterial agent is 600 mg·L-1,the antibacterial rate of Escherichia coli(E.coli) reaches 99.99% irradiated by visible light for30 min,and when the concentration of antibacterial agent is 200 mg·L-1,the antibacterial rate of Staphylococcus aureus(S.aureus) reaches 99.99% irradiated by visible light for 25 min.We also analyzed the reasons in detail from the aspects of bacterial species and antibacterial mechanism,and proposed the antibacterial mechanism of·O2-and h+as the main active species.These findings suggest that T-ZIF-8-TDI photocatalytic antibacterial agent has potential for use in self-cleaning of building exterior walls.

关键词： ZIF-8 Hot oxygen sensitization Modified by isocyanate Antimicrobial performance Photocatalytic antibacterial mechanism

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Trends of obesity and overweight among children and adolescentsin China

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World Journal of Pediatrics 2023年第12期19卷 1115-1126页

作者： Ye Hong Rahim Ullah Jian‑Bing wang Jun‑fen Fu Department of Endocrinology Children’s HospitalZhejiang University School of MedicineNational Clinical Research Center for Child HealthNational Children’s Regional Medical CenterHangzhou 310052China Zhejiang University School of Medicine Hangzhou 310052China

Background Recent decades have shown a rapid increase in the prevalence of overweight and obesity among Chinese children based on several national surveys.Restrictions due to the coronavirus disease 2019 outbreak have worsened its epidemiol-ogy.This review updates the trends in the prevalence of overweight and obesity among Chinese children and adolescents and analyzes the underlying reasons to provide evidence for better policy making.Methods Studies published in English and Chinese were retrieved from PubMed,Google Scholar,China National Knowl-edge Infrastructure andWanfang.Results The prevalence of overweight and obesity has been increasing for decades and varies with age,sex and geography but is more pronounced in primary school students.The increase in obesity in boys appeared to be slower,whereas that in girls showed a declining trend.The northern areas of China have persistently maintained the highest levels of obesity with a stable trend in recent years.Meanwhile,the prevalence in eastern regions has dramatically increased.Notably,the overall prevalence of obesity in children has shown a stabilizing trend in recent years.However,the occurrence of obesity-related metabolic diseases increased.The effect of migrants floating into east-coast cities should not be neglected.Conclusions The high prevalence of overweight and obesity among Chinese children and adolescents persists but with vary-ing patterns.Obesity-related metabolic diseases occur more frequently despite a stable trend of obesity.Multiple factors are responsible for the changing prevalence.Thus,comprehensive and flexible policies are needed to effectively manage and prevent the burden of obesity and its related complications.

关键词： Adolescents Children Obesity Overweight Policy

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Evaluation of a deep-learning model for multispectral remote sensing of land use and crop classification

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The Crop Journal 2022年第5期10卷 1435-1451页

作者： Lijun wang Jiayao wang Zhenzhen Liu Jun Zhu fen Qin Henan Industrial Technology Academy of Spatio-Temporal Big Data Henan UniversityKaifeng 475004HenanChina College of Geography and Environmental Science Henan UniversityKaifeng 475004HenanChina Key Laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions Ministry of EducationHenan UniversityKaifeng 475004HenanChina Key Research Institute of Yellow River Civilization and Sustainable Development Ministry of EducationHenan UniversityKaifeng 475004HenanChina Henan Technology Innovation Center of Spatial-Temporal Big Data Henan UniversityKaifeng 475004HenanChina

High-resolution deep-learning-based remote-sensing imagery analysis has been widely used in land-use and crop-classification mapping. However, the influence of composite feature bands, including complex feature indices arising from different sensors on the backbone, patch size, and predictions in transferable deep models require further testing. The experiments were conducted in six sites in Henan province from2019 to 2021. This study sought to enable the transfer of classification models across regions and years for Sentinel-2 A(10-m resolution) and Gaofen PMS(2-m resolution) imagery. With feature selection and up-sampling of small samples, the performance of UNet++ architecture on five backbones and four patch sizes was examined. Joint loss, mean Intersection over Union(m Io U), and epoch time were analyzed, and the optimal backbone and patch size for both sensors were Timm-Reg Net Y-320 and 256 × 256, respectively. The overall accuracy and Fscores of the Sentinel-2 A predictions ranged from 96.86% to 97.72%and 71.29% to 80.75%, respectively, compared to 75.34%–97.72% and 54.89%–73.25% for the Gaofen predictions. The accuracies of each site indicated that patch size exerted a greater influence on model performance than the backbone. The feature-selection-based predictions with UNet++ architecture and upsampling of minor classes demonstrated the capabilities of deep-learning generalization for classifying complex ground objects, offering improved performance compared to the UNet, Deeplab V3+, Random Forest, and Object-Oriented Classification models. In addition to the overall accuracy, confusion matrices,precision, recall, and F1 scores should be evaluated for minor land-cover types. This study contributes to large-scale, dynamic, and near-real-time land-use and crop mapping by integrating deep learning and multi-source remote-sensing imagery.

关键词： Land use and crop classification Deep learning High-resolution image Feature selection UNet++

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A Numerical Study of Multiple Solutions for Laminar Flows in a Porous and Moving Channel

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Numerical Mathematics(Theory,Methods and Applications) 2018年第1期11卷 74-91页

作者： Fen Wang Ping Lin Lin Li Yongyue Jiang Beijing Key Laboratory for Magneto-Photoelectrical Composite and Interface Science School of Mathematics and PhysicsUniversity of Science and Technology BeijingBeijing 100083China Division of Mathematics University of DundeeDundee DD14HNUnited Kingdom Beijing Time Technologies Co. Ltd.Kaituo Road 17BeijingChina

In this paper,based on the finite element formulation,we focus on multiple solutions and their evolution with time for a laminar flow in a permeable channel with expanding or contracting walls.Both Newtonian fluid and micropolar fluid are consid-ered.For the Newtonian fluid model,we find that the profile of the unique solution in the case of injection remains the same for long time,which indicates that the solution may be stable.On the other hand,in the case of large suction,the profile of multiple solutions changes in time,which suggests that the multiple solutions may be unstable.Similar behaviors and conclusions are observed for the micropolar fluid model under different boundary parameters.

关键词： Newtonian fluid micropolar fluid multiple solutions finite element method bvp4c

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