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Phase transition of multi-component(TiZrVNb)C ceramics—Part II:From single phase to multiple phases via adjusting V content

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Journal of Advanced Ceramics 2024年第5期13卷 689-698页

作者： Qingyi Kong Lei Chen Sijia Huo Kunxuan Li Wenyu Lu yujin wang Yu Zhou Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150080China Key Laboratory of Advanced Structure‒Function Integrated Materials and Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China National Key Laboratory of Precision Hot Processing of Metals Harbin Institute of TechnologyHarbin 150001China

To address the relatively mediocre mechanical properties of single-phase multi-component carbide ceramics,a phase transition from a single phase to multiple phases was proposed to achieve superior mechanical properties.A series of(TiZrVxNb)C0.8 ceramics with different V contents were fabricated by spark plasma sintering(SPS).The influence of the V content on the phase composition,microstructural evolution,and mechanical properties was investigated in detail.The transition behavior from a single phase to multiple phases is discovered and discussed.The formation of the Zr-rich phase and Zr-poor phase can be attributed to the increase in lattice distortion and mixed enthalpy caused by the addition of V.A nanometer lamellar structure with a semi-coherent interface obtained via in situ decomposition is reported for the first time in multi-component carbide ceramics.The semi-coherent interfaces with high dislocation density and strain concentration effectively improve the mechanical properties,grain refinement,and multi-phase formation.The optimal comprehensive mechanical properties of the Vickers hardness(26.3 GPa),flexural strength(369 MPa),and fracture toughness(3.1 MPa·m1/2)were achieved for the sample with 20 mol%V.

关键词： multi-component ceramics multiple phases microstructure evolution phase decomposition mechanical properties

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Phase transition of multi-component(TiZrVNb)C ceramics—Part I:Phase decomposition induced by carbon content

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Journal of Advanced Ceramics 2024年第5期13卷 679-688页

作者： Qingyi Kong Rao Zhang Lei Chen Sijia Huo Wenyu Lu yujin wang Boxin Wei Yu Zhou Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150080China Key Laboratory of Advanced Structure‒Function Integrated Materials and Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China School of Materials Science and Chemical Engineering Harbin University of Science and TechnologyHarbin 150001China National Key Laboratory of Precision Hot Processing of Metals Harbin Institute of TechnologyHarbin 150001China

Phase decomposition can effectively enhance the mechanical properties of carbide ceramics and can overcome the difficulty of enhancing the mechanical properties of single-phase multicomponent carbide ceramics.In this work,a series of nonstoichiometric(TiZrVNb)Cx ceramics were prepared by spark plasma sintering(SPS)at different temperatures.The effects of the carbon content on the phase composition,microstructure evolution,and mechanical properties were investigated in detail.Phase decomposition occurred with decreasing carbon content.Two different solid solutions of(Ti,V)-rich and Zr-rich phases formed from the decomposition of equimolar single-phase solid solutions,namely,the Zr-poor phase and Zr-rich phase,respectively.The distribution of Nb element is relatively uniform.The semicoherent interfaces between the Zr-poor phase and the Zr-rich phase can harden and strengthen effectively under the synergistic effect of grain refinement.Ceramics with phase decomposition structures have apparent advantages compared to single-phase high-entropy carbides.This work provides an important train of thought for the microstructure tailoring and properties optimization of multi-component carbide ceramics.

关键词： multicomponent ceramics nontoichiometry microstructure evolution phase decomposition mechanical properties

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Recent Advances in Microbial Production of Terpenoids from Biomass-derived Feedstocks

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Chemical Research in Chinese Universities 2024年第1期40卷 20-28页

作者： CAO yujin XIAN Mo CAS Key Laboratory of Biobased Materials Qingdao Institute of BioEnergy and Bioprocess TechnologyChinese Academy of SciencesQingdao 266101P.R.China Shandong Energy Institute Qingdao 266101P.R.China Qingdao New Energy Shandong Laboratory Qingdao 266101P.R.China

Terpenoids are a diverse class of natural products widely used as pharmaceuticals,perfumes,flavors,and biofuels.Traditionally,terpenoids are obtained from natural sources,such as plants,but their production is limited by the insufficiency of resources and low yields of extraction.Microbial production of terpenoids has emerged as a promising alternative due to that it is sustainable and easy to scale up.This review aims to summarize recent advances in microbial production of terpenoids from inexpensive biomass-derived feedstocks.Metabolic pathways and key enzymes involved in terpenoid biosynthesis are introduced.Microorganisms that can utilize low-cost lignocellulosic feedstocks for terpenoid production are highlighted.The challenges and prospects faced by microbial terpenoid production are proposed.We believe that continuous progress in the fields of biomass transformation and synthetic biology will ultimately achieve industrial production of microbial terpenoids.

关键词： Terpenoid Microbial production Biomass-derived feedstock Metabolic pathway

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Circular RNA circ_0003609 ameliorates hypertrophied ligamentum flavum by regulating the miR-155/SIRT1 axis

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BIOCELL 2024年第6期48卷 1001-1008页

作者： GUIBIN ZHONG SHURONG wang yujin HE DAMING FENG KE WEI YANQIU YANG JIANWEI CHEN JUNLING CHEN Department of Orthopaedics Baoshan BranchRen Ji HospitalSchool of Medicine Shanghai Jiao Tong UniversityShanghai200444China Department of Orthopaedics Ren Ji HospitalSchool of Medicine Shanghai Jiao Tong UniversityShanghai200127China Department of Operation and Anaesthesia Ren Ji HospitalSchool of Medicine Shanghai Jiao Tong UniversityShanghai200127China Department of Orthopaedics Huai Yuan Chang Jiu HospitalHuaiyuan233499China

Background:Hypertrophy of the ligamentumﬂavum(HLF)is a common contributor to spinal stenosis which results in signiﬁcant neurological impairments.Circular RNA(circRNA)circ_0003609 has been linked to HLF;however,the exact mechanism by which it causes this disease is unclear.Methods:Circ_0003609 expressions were regulated in HLF cells by overexpression vectors and RNA interference.Cell proliferation andﬁbrosis-related gene expression were checked by the Cell Counting Kit-8(CCK-8)assay and western blotting.CircBank’s prediction of the association between miR-155 and circ_0003609 was supported by a dual-luciferase reporter experiment.The function of the miR-155/sirtuin 1(SIRT1)axis in controlling HLFﬁbrosis was further examined.Results:Overexpression of circ_0003609 suppressed HLF cell propagation andﬁbrosis compared to its silencing.It was found that circ_0003609 served as the sponge for miR-155 and that the circ_0003609/miR-155 axis controlled theﬁbrosis of HLF cells.It was found that circ_0003609 acted as a sponge for miR-155,regulating theﬁbrosis of HLF cells.Further,miR-155 targets SIRT1,and the miR-155/SIRT1 axis promotes HLF cellﬁbrosis.Conclusion:Circ_0003609 ameliorates hypertrophied ligamentumﬂavum(LF)by modulating the miR-155/SIRT1 axis,indicating a potential treatment approach for HLF.

关键词： Circular RNA Circ_0003609 Hypertrophy of ligamentum flavum MiR-155 Sirtuin 1 Fibrosis

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Impact resistance performance and optimization of the sand-EPE composite cushion in rock sheds

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Journal of Mountain Science 2024年第2期21卷 676-689页

作者： YU Bingxin ZHOU Xiaojun TANG Jianhui ZHANG yujin ZHANG Yuefeng School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China

Rock sheds are widely used to prevent rockfall disasters along roads in mountainous areas.To improve the capacity of rock sheds for resisting rockfall impact,a sand and expandable polyethylene(EPE)composite cushion was proposed.A series of model experiments of rockfall impact on rock sheds were conducted,and the buried depth of the EPE foam board in the sand layer was considered.The impact load and dynamic response of the rock shed were investigated.The results show that the maximum impact load and dynamic response of the rock shed roof are all significantly less than those of the sand cushion.Moreover,as the distance between the EPE foam board and rock shed roof decreases,the maximum rockfall impact force and impact pressure gradually decrease,and the maximum displacement,acceleration and strain of the rock shed first decrease and then change little.In addition,the vibration acceleration and vertical displacement of the rock shed roof decrease from the centre to the edge and decrease faster along the longitudinal direction than that along the transverse direction.In conclusion,the buffering effect of the sand-EPE composite cushion is better than that of the pure sand cushion,and the EPE foam board at a depth of 1/3 the thickness of the sand layer is appropriate.

关键词： Rockfall Rock shed Impact Composite cushion Buffering effect Dynamic response

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Influence of Repetitive Impulse Waveforms on Surface Discharge Characteristics and Insulation Life for Polyimide Film

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 746-755页

作者： Zhiyun Han Qingmin Li yujin Guo Tao Liu Guojing Dong Hanwen Ren State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China Electric Power Research Institute Beijing 100085China Inner Mongolia Electric Economy and Technology Academy Hohhot 010020China

Accelerated insulation aging problems under high frequency repetitive impulses in power electronic transformers are drawing more and more attention in modern power systems. Partial discharge (PD) characteristics including discharge inception voltage, phase distribution and statistical characteristics on polyimide (PI) surface under different impulse waveforms and the insulation life of PI films are studied in this paper. We carry out experiments based on PD and insulation lifetime test systems, using five different types of repetitive impulses, including three bipolar waves and two unipolar waves. The experimental results show that there is little variation in discharge inception voltage under different waveforms, but great variation in phase distribution and statistical characteristics of PD. In addition, insulation life is approximately the same under different waveforms with the same polarity, and the aging rate under bipolar waveforms is larger than that under unipolar waveforms. We explain the differences between the bipolar and unipolar waveforms on insulation life, which can be concluded that the surface charge under unipolar waveform accumulates more significnatly compared with bipolar waveform and decreases the electric filed strength in discharging the air gap and inhibits surface discharge from occurring.

关键词： Insulation life polyimide film power electronic transformer repetitive impulse surface discharge characteristics

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Mechanical properties,thermal conductivity and defect formation energies of samarium immobilization in Gd_(2)Zr_(2)O_(7):First-principles study and irradiation experiment

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Journal of Rare Earths 2023年第3期41卷 422-433,I0004页

作者： Yuhao wang Jiahu Ouyang Tao Wei Gui Cao Zhanguo Liu Zhaoying Ding yujin wang Yaming wang Key Laboratory of Advanced Structural-Functional Integration Materials&Green Manufacturing Technology School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China Nuclear Fuel Cycle Research Theme Australian Nuclear Science and Technology OrganisationLocked Bag 2001Kirrawee DCNSW2232Australia

A density functional theory(DFT)study was employed to investigate the mechanical property,thermal conductivity,Debye temperature,electronic structure and defect chemistry of(Gd_(1-x)Sm_(x))_(2)Zr_(2)O_(7).All the(Gd_(1-x)Sm_(x))_(2)Zr_(2)O_(7) compounds exhibit an excellent structural and mechanical stability(Gd_(0.25)Sm_(0.75))_(2)Zr_(2)O_(7) has the lowest Young’s modulus of 213.7 GPa,the largest Possion’s ratio of 0.292,the lowest Debye temperature of 491.8 K and the lowest thermal conductivity.The calculated thermal conductivities of(Gd_(1-x)Sm_(x))_(2)Zr_(2)O_(7) are 1.17-1.21 W/(m·K)by the Clark’s model and 1.32-1.36 W/(m·K)by the Cahall’s model,respectively.The formation energies of O vacancies at 48f site are negative,which increase with the Sm content,however,the formation energies of O vacancies at 8b site are almost invariable.In addition,Sm partly occupying the Gd-site reduces distinctly the formation energies of defects such as A-site vacancies,cation antisite defects,anion Frenkel pairs of oxygen at 8b site and cation interstitials,which suggests that Sm-doped Gd_(2)Zr_(2)O_(7),especially equimolar GdSmZr_(2)O_(7),has a better irradiation tolerance.After the 16 MeVTa-ion irradiation at a fluence of 1×10^(14) or 2×10^(14) ions/cm^(2),the crystal structure of GdSmZr_(2)O_(7) transforms from pyrochlore to a defect fluorite without obvious amorphous phase.

关键词： Pyrochlores First-principles calculations Mechanical properties Defect formation energies Ion irradiation Rare earths

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Insights into grain boundary segregation and solubility limit of Cr in(TiZrNbTaCr)C

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Journal of Materials Science & Technology 2023年第8期139卷 1-9页

作者： Wentao Su Lei Chen Wen Zhang Sijia Huo yujin wang Yu Zhou Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China Key Laboratory of Advanced Structure-Function Integrated Materials and Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China

Dense(TiZrNbTaCr)C with Cr segregation along grain boundaries(GBs)has been first proposed and fabri-cated by pressureless sintering at 1800-2000℃,utilizing the self-synthesized carbide powders obtained by carbothermal reduction.Cr segregation along GBs is successfully realized as expected via optimizing the initial Cr content.When Cr content is more than 11.12 at.%,Cr addition is excessive and results in Cr-rich second phase formation at triple junctions.To analyze the Cr solubility dependence on tempera-ture and initial Cr content,the Cr content in(TiZrNbTaCr)C grains is investigated by EDS.The solubility limit of Cr in(TiZrNbTaCr)C is about 3.8 at.%at 1900℃.Finally,Vickers hardness of all the samples is measured to assess the mechanical property of(TiZrNbTaCr)C ceramics.The basic understanding of the Cr solubility limit and GB segregation feature in(TiZrNbTaCr)C have been preliminarily clarified,which may pave a potential way to design and tailor microstructure and GB feature of(TiZrNbTaCr)C for the purpose of enhancing its properties in the future.

关键词： High-entropy carbide Grain boundary segregation Solubility limit Microstructure

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The highest melting point material:Searched by Bayesian global optimization with deep potential molecular dynamics

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Journal of Advanced Ceramics 2023年第4期12卷 803-814页

作者： Yinan wang Bo Wen Xingjian Jiao Ya Li Lei Chen yujin wang Fu-Zhi Dai Artificial Intelligence for Science Institute Beijing 100084China Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China College of Computer Science and Technology Heilongjiang Institute of TechnologyHarbin 150001China Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China Key Laboratory of Advanced Structural-Functional Integration Materials&Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China DP Technology Bejing 100080China

The interest in refractory materials is increasing rapidly in recent decades due to the development of hypersonic vehicles.However,the substance that has the highest melting point(Tm)keeps a secret,since precise measurements in extreme conditions are overwhelmingly difficult.In the present work,an accurate deep potential(DP)model of a Hf-Ta-C-N system was first trained,and then applied to search for the highest melting point material by molecular dynamics(MD)simulation and Bayesian global optimization(BGO).The predicted melting points agree well with the experiments and confirm that carbon site vacancies can enhance the melting point of rock-saltstructure carbides.The solid solution with N is verified as another new and more effective melting point enhancing approach for HfC,while a conventional routing of the solid solution with Ta(e.g.,HfTa_(4)C_(5))is not suggested to result in a maximum melting point.The highest melting point(~4236 K)is achieved with the composition of HfCo.638No.271,which is~80 K higher than the highest value in a Hf-C binary system.Dominating mechanism of the N addition is believed to be unstable C-N and N-N bonds in liquid phase,which reduces liquid phase entropy and renders the liquid phase less stable.The improved melting point and less gas generation during oxidation by the addition of N provide a new routing to modify thermal protection materials for the hypersonic vehicles.

关键词： melting point(T_(m)) carbides carbonitrides deep potential(DP) Bayesiannglobal optimization(BGO)

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Insight into the role of ethylene glycol on thermodynamics and nucleation kinetics of dimethyl terephthalate in mixed solvent system

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Particuology 2024年第2期85卷 1-12页

作者： yujin Zhang Chunyan Shi Jing Tang Li Liu Dongxia Yan Qing Zhou Xingmei Lu Songyan Jia College of Chemical Engineering Shenyang University of Chemical TechnologyShenyang110142China Bejing Key Laboratoryoflonic Liquids Clean Process CAS Key LaboratoryofGreen Process and EngineeringState Key Laboratoryof Multiphase Complex SystemsInstitute of Process EngineeringChinese Academy of SciencesBeijing100190China School of Chemistry and Chemical Engineering Qingdao UniversityQingdao266071China Henan Institute of Advanced Technology Zhengzhou UniversityZhengzhou450001China School of Chemical Engineering University of Chinese Academy of SciencesBeijing100049China

Dissolution and nucleation are two essential processes for industrial crystallization.This paper in-vestigates the effect of ethylene glycol addition on the crystallization behavior of dimethyl terephthalate(DMT)in solution.The DMT solubility in mixed solvent system(methanol-ethylene glycol)was deter-mined by isothermal satiation approach,and the solubility was associated using seven models.The model fitting results were consistent with the experimental values.Based on the results,the metastable zone width(MSZW)of DMT was detected by the polythermal approach;the modified Sangwal's theory was used to investigate the nucleation behavior,which can provide a new way of thought for better analysis of the crystallization behavior.The results demonstrated that MSZW was associated with various elements,such as cooling rate,saturation temperature and mass fraction of ethylene glycol.The addition of ethylene glycol slowed down the nucleation rate as shown by the broadening of MSZW.We derive the solid-liquid interface energy,the nucleation driving force,the critical nucleation size and the critical Gibbs free energy according to the classical nucleation theory.It is demonstrated that the nucleation driving force and the solid-liquid interface energy are dependent and jointly influence the MSZW.

关键词： Dissolution Nucleation Solubility Apparent thermodynamic parameters Metastable zone width Solid-liquid interface energy

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