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Simultaneous enhancement of mechanical and shape memory properties by heat-treatment homogenization of Ti_(2)Ni precipitates in TiNi shape memory alloy fabricated by selective laser melting

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Journal of Materials Science & Technology 2022年第6期101卷 205-216页

作者： H.Z.Lu L.H.Liu C.yang X.Luo C.H.Song Z.Wang J.Wang y.d.su y.F.ding L.C.Zhang y.y.Li National Engineering Research Center of Near-net-shape Forming for Metallic Materials South China University of TechnologyGuangzhou 510640China Musculoskeletal Oncology department Sun Yat-Sen University Cancer CenterGuangzhouGuangdong ProvinceChina Shenyang Aircraft design and Research Institute Shenyang 110035China Guangdong Huayi Plumbing Fittings Industry Co. Ltd.Kaiping 529321China School of Engineering Edith Cowan University270 Joondalup DriveJoondalupPerthWA 6027Australia

The excellent shape memory and mechanical properties of Ti Ni shape memory alloys(SMAs) fabricated using selective laser melting(SLM) are highly desirable for a wide range of critical applications. In this study, we examined the simultaneous enhancement of mechanical and shape memory properties using heat-treatment homogenization of Ti_(2)Ni precipitates in a Ti_(50.6)Ni_(49.4)SMA fabricated using SLM. Specifically, because of the complete solution treatment, nanoscale spherical Ti_(2)Ni precipitates were homogeneously dispersed throughout the grain interior. Interestingly, the resultant SMA exhibited an ultrahigh tensile strength of 880 ± 13 MPa, a large elongation of 22.4 ± 0.4%, and an excellent shape memory effect, with a recovery rate of > 98% and ultrahigh recoverable strain of 5.32% after ten loading–unloading cycles. These simultaneously enhanced properties are considerably superior than those of most previously reported Ti Ni SMAs fabricated using additive manufacturing. Fundamentally, the enhancement in tensile strength is ascribed to precipitation strengthening and work hardening, and the large plasticity is mainly attributed to the homogeneous nanoscale globular Ti_(2)Ni precipitates, which effectively impeded the rapid propagation of microcracks. Furthermore, the enhanced shape memory properties are derived from the suppression of dislocation movement and formation of retained stabilized martensite by the presence of high-density dislocations, nanoscale Ti_(2)Ni precipitates, and abundant interfaces. The obtained results provide insight into the enhancement of the two types of properties in Ti Ni SMAs and will accelerate the wider application of SMAs.

关键词： Shape memory alloy Selective laser melting Heat treatment Mechanical properties Shape memory properties

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A new design of dual-constituent triangular lattice metamaterial with unbounded thermal expansion

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Acta Mechanica Sinica 2019年第3期35卷 507-517页

作者： y.C.Zhang y.J.Liang S.T.Liu y.d.su State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian 116024China New Functional Structural design and Verification Key Laboratory of Aeronautical Technology Shenyang 110035China

Triangular lattice metamaterials composed of bi-layer curved rib elements (called the Lehman-Lakes lattice) possess unbounded thermal expansion, high stiffness and impossibility of thermal buckling, which are highly desirable in many engineering structural applications subjected to large fluctuations in temperature. However, the requirement of such lattice metamaterial is that it must be a hinged joint in order to achieve the bending deformation upon heating freely, which directly leads to poor manufacturability, especially in small dimensions. In this study, a new design of dual-constituent triangular lattice metamaterial (dTLM) with good manufacturability is proposed to achieve the identical unbounded thermal expansion. In this lattice, a special bi-layer curved rib element where layer one is partially covered by layer two is presented, where the hinge joints are not necessary because the flexural rigidity in the single-layer part is much smaller than that in the bi-layer part, and the desirable thermal bending deformation can be achieved. A sample fabricated by additive manufacturing is given in order to show the good manufacturability;simultaneously, the multifunctional performance of the tailored dTLM with zero, large positive or negative coefficient of thermal expansion (CTE) can remain excellent, as well as the Lehman-Lakes lattice. Examples illustrate that the dTLM with zero CTE has about 34.2% improvement in stiffness and meanwhile has 17% reduction in weight compared with the Lehman-Lakes lattice. The stiffness of the dTLM has a moderate reduction when achieving the same large positive or negative CTE. In addition, the thermomechanical properties of the dTLM are given by the closed-form analytical solution and their effectiveness is verified by the detailed numerical simulation.

关键词： Metamaterial Zero thermal expansion Lattice material Multifunctional design Additive manufacturing

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Shock Formation for 2d Isentropic Euler Equations with Self-similar Variables

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Chinese Annals of Mathematics,Series B 2024年第3期45卷 349-412页

作者： Wenze su School of Mathematical Sciences Fudan University

The author studies the 2d isentropic Euler equations with the ideal gas law.He exhibits a set of smooth initial data that give rise to shock formation at a single point near the planar symmetry.These solutions to the 2d isentropic Euler equations are associated with non-zero vorticity at the shock and have uniform-in-time■-H■lder bound.Moreover,these point shocks are of self-similar type and share the same profile,which is a solution to the 2d self-similar Burgers equation.The proof of the solutions,following the3d construction of Buckmaster,Shkoller and Vicol (in 2023),is based on the stable 2d self-similar Burgers profile and the modulation method.

关键词： 2d isentropic Euler equations Shock formation Self-similar solution 35Q31 35L67 35B44

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Molecular evolution of Toll-like receptors in rodents

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Integrative Zoology 2024年第3期19卷 371-386页

作者： Qianqian su yi CHEN Hongxuan HE College of Forestry Central South University of Forestry and TechnologyChangshaChina National Research Center for Wildlife-Borne diseases Institute of ZoologyChinese Academy of SciencesBeijingChina

Toll-like receptors(TLRs),the key sensor molecules in vertebrates,trigger the innate immunity and prime the adaptive immune system.The TLR family of rodents,the largest order of mammals,typically contains 13 TLR genes.However,a clear picture of the evolution of the rodent TLR family has not yet emerged and the TLR evolutionary patterns are unclear in rodent clades.Here,we analyzed the natural variation and the evolutionary processes acting on the TLR family in rodents at both the interspecific and population levels.Our results showed that rodent TLRs were dominated by purifying selection,but a series of positively selected sites(PSSs)primarily located in the ligand-binding domain was also identified.The numbers of PSSs differed among TLRs,and nonviralsensing TLRs had more PSSs than those in viral-sensing TLRs.Gene-conversion events were found between TLR1 and TLR6 in most rodent species.Population genetic analyses showed that TLR2,TLR8,and TLR12 were under positive selection in Rattus norvegicus and R.tanezumi,whereas positive selection also acted on TLR5 and TLR9 in the former species,as well as TLR1 and TLR7 in the latter species.Moreover,we found that the proportion of polymorphisms with potentially functional change was much lower in viral-sensing TLRs than in nonviral-sensing TLRs in both of these rat species.Our findings revealed the first thorough insight into the evolution of the rodent TLR genetic variability and provided important novel insights into the evolutionary history of TLRs over long and short timescales.

关键词： adaptive evolution gene conversion positive selection rodents Toll-like receptors

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Risk factors for long COVId in children and adolescents:a systematic review and meta-analysis

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World Journal of Pediatrics 2024年第2期20卷 133-142页

作者： daniel G.Rayner Elaine Wang Cloris su Om d.Patel Stephanie Aleluya Alessandra Giglia Evelyn Zhu Maha Siddique department of Health Research Methods Evidenceand ImpactFaculty of Health SciencesMcMaster University1280 Main St WHamiltonONL8S 4K1Canada Faculty of Health Sciences McMaster University1280 Main St WHamiltonON L8S 4K1Canada Faculty of Science McMaster University1280 Main St WHamiltonONL8S 4K1Canada

Background The long-term sequelae of COVId-19 in children and adolescents remain poorly understood and characterized.This systematic review and meta-analysis sought to summarize the risk factors for long COVId in the pediatric population.Methods We searched six databases from January 2020 to May 2023 for observational studies reporting on risk factors for long COVId or persistent symptoms those were present 12 or more weeks post-infection using multivariable regression analyses.Trial registries,reference lists of included studies,and preprint servers were hand-searched for relevant studies.Random-effects meta-analyses were conducted to pool odds ratios for each risk factor.Individual study risk of bias was rated using QUIPS,and the GRAdE framework was used to assess the certainty of evidence for each unique factor.Results Sixteen observational studies(N=46,262)were included,and 19 risk factors were amenable to meta-analysis.With moderate certainty in the evidence,age(per 2-year increase),allergic rhinitis,obesity,previous respiratory diseases,hospitalization,severe acute COVId-19,and symptomatic acute COVId-19 are probably associated with an increased risk of long COVId.Female sex,asthma,comorbidity,and heart diseases may be associated with an increased risk of long COVId,and Asian and Black races may be associated with a decreased risk of long COVId.We did not observe any credible subgroup effects for any risk factor.Conclusions The current body of literature presents several compelling risk factors for the development of long COVId in the pediatric population.Further research is necessary to elucidate the pathophysiology of long COVId.

关键词： COVId-19 Long COVId Post-acute COVId-19 syndrome Pediatrics Risk factors

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A versatile model with three-dimensional triangular lattice for unconventional transport and various topological effects

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National Science Review 2024年第1期11卷 204-214页

作者： Jing-yang you Gang su yuan Ping Feng department of Physics National University of Singapore Kavli Institute for Theoretical Sciences and CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Centre for Advanced 2d Materials National University of Singapore

The finite Berry curvature in topological materials can induce many subtle phenomena, such as the anomalous Hall effect(AHE), spin Hall effect(SHE), anomalous Nernst effect(ANE), non-linear Hall effect(NLHE) and bulk photovoltaic effects. To explore these novel physics as well as their connection and coupling, a precise and effective model should be developed. Here, we propose such a versatile model—a 3d triangular lattice with alternating hopping parameters, which can yield various topological phases,including kagome bands, triply degenerate fermions, double Weyl semimetals and so on. We reveal that this special lattice can present unconventional transport due to its unique topological surface states and the aforementioned topological phenomena, such as AHE, ANE, NLHE and the topological photocurrent effect. In addition, we also provide a number of material candidates that have been synthesized experimentally with this lattice, and discuss two materials, including a non-magnetic triangular system for SHE, NLHE and the shift current, and a ferromagnetic triangular lattice for AHE and ANE. Our work provides an excellent platform, including both the model and materials, for the study of Berry-curvature-related physics.

关键词： three-dimensional triangular lattice different topological phases various topological effects Berry curvature

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Multiresponsive,easy-reversible,and dual-visual Pt(Ⅱ)salt nanostructures for advanced anti-counterfeiting application

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Nano Research 2024年第1期17卷 372-381页

作者： Zhen su§ depeng Li§ Lixin Zhang Si Tian yuhong su Xiaoyun Hu duan Xiong Qingqing Guan Key Laboratory of Oil and Gas Fine Chemicals Ministry of Education College of Chemical EngineeringXinjiang UniversityUrumqi 830017China

Smart materials that integrate multi-stimuli response,full reversibility,and dual-visual read-out channel are highly desired for anticounterfeiting and information encryption applications.Herein,we developed a multiresponsive perchlorate terpyridyl Pt(Ⅱ)nano complex which could undergo fully reversible conversion between three forms stimulated by water or formaldehyde molecule due to the extent of Pt–Pt interaction.Meanwhile,a dual-visual channel,i.e.,the colorimetric channel changed from yellow to orange or red and the corresponding luminescent channel from orange to orange-red or red,has also been found.The weak and equivalent strength of ion-dipole interaction and hydrogen bond that generated between formaldehyde/water and Pt(II)salt result in the easy-control reversibility between the three forms.Furthermore,by introducing different polymer matrices,1Cl·ClO_(4)@PMMA(1Cl·ClO_(4):[Pt(tpy)Cl]·ClO4,tpy:2,2':6',2''-terpyridine),PMMA:poly(methyl methacrylate))and 1Cl·ClO4@PVA(PVA:polyvinyl alcohol)are successfully constructed,which exhibit different reversible behaviors since the PMMA and PVA matrix exert different influences on the strength of hydrogen-bond.Those smart Pt(II)salt nanostructures present great potential for high-security-level anticounterfeiting application.

关键词： Pt(II)complex multiresponse reversibility anticounterfeiting information encryption

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The main strategies for soil pollution apportionment:A review of the numerical methods

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Journal of Environmental Sciences 2024年第2期136卷 95-109页

作者： Bin Shi Jing Meng TieyuWang Qianqian Li Qifan Zhang Guijin su Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China Guangdong Provincial Key Laboratory of Marine disaster Prediction and Prevention Shantou UniversityShantou 515063China

Nowadays,a large number of compounds with different physical and chemical properties have been determined in soil.Environmental behaviors and source identification of pollutants in soil are the foundation of soil pollution control.Identification and quantitative analysis of potential pollution sources are the prerequisites for its prevention and control.Many efforts have made to develop methods for identifying the sources of soil pollutants.These efforts have involved the measurement of source and receptor parameters and the analysis of their relationships via numerical statistics methods.We have comprehensively reviewed the progress made in the development of source apportionment methodologies to date and present our synthesis.The numerical methods,such as spatial geostatistics analysis,receptor models,and machine learning methods are addressed in depth.In most cases,however,the effectiveness of any single approach for source apportionment remains limited.Combining multiple methods to address soil quality problems can reduce uncertainty about the sources of soil pollution.This review also constructively highlights the key strategies of combining mathematical models with the assessment of chemical profiles to provide more accurate source attribution.This review intends to provide a comprehensive summary of source apportionment methodologies to help promote further development.

关键词： Soil pollutants Source attribution Methodologies Chemical profiles Mathematical models

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Experimental Investigation of the Operating Characteristics of a Pulsating Heat Pipe with Ultra-Pure Water and Micro Encapsulated Phase Change Material suspension

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Journal of Thermal Science 2024年第2期33卷 457-468页

作者： SHI Weixiu su Xiaoyang CHEN Hongdi PAN Lisheng Beijing Engineering Research Center of sustainable Energy and Buildings Beijing University of Civil Engineering and ArchitectureBeijing100044China School of Environment and Energy Engineering Beijing University of Civil Engineering and ArchitectureBeijing100044China State Key Laboratory of High Temperature Gas dynamics Institute of MechanicsChinese Academy of SciencesBeijing100190China

The specific heat capacity of working fluid is an important influence factor on heat transfer characteristic of the pulsating heat pipe(PHP).due to the relatively large specific heat capacity of micro encapsulated phase change material(MEPCM) suspension,a heat transfer performance experimental facility of the PHP was established.The heat transfer characteristic with MEPCM suspension of different mass concentrations(0.5% and 1.0%) and ultra-pure water were compared experimentally.It was found that when the PHP uses MEPCM suspension as its working fluid,operating stability is impoverished under lower heating power and the operating stability is better under higher heating power.At the inclination angle of 90°,the temperature at heating side decreases compared to ultra-pure water and the temperature at heating side decreases with the raising of MEPCM suspension mass concentration.The heat transfer characteristic of the PHP is positively correlated with the inclination angle and the 90° is optimum.The unfavorable effect of the inclination angle decreases with heating power increasing.When the inclination angle is 90°,the PHP with MEPCM suspension at 1.0% of mass concentration has the lowest thermal transfer resistance and followed by ultra-pure water and MEPCM suspension at 0.5% of mass concentration has the highest thermal transfer resistance.When the inclination angles are 60° and30°,the effect of gravity on the flow direction is reduced to 86.6% and 50% of that on the inclination angle of 90°,respectively,and the promoting effect of gravity on the working fluid is further weakened as the inclination angle further decreases.due to the high viscosity of MEPCM suspension,the PHP with ultra-pure water has the lowest heat transfer resistance.When the inclination angles is 60°,the thermal resistance with MEPCM suspension at0.5% of the mass concentration is lower than that at 1.0% at the heating power below 230 W.The thermal resistance of MEPCM suspension tends to be similar for heating power of 230-250 W.At the heating

关键词： pulsating heat pipe(PHP) micro encapsulated phase change material(MEPCM) heat transfer characteristic inclination angle

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Structure and Representations for Electrical Lie Algebra of Type d_(5)

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Algebra Colloquium 2024年第2期31卷 271-284页

作者： yulu Chen Ran Shen yucai su College of Science Donghua UniversityShanghai 201620China 不详

In this paper,we prove that the electrical Lie algebra e d_(5)is isomorphic to the semidirect product of sp_(4)and a 2-step nilpotent Lie algebra.Furthermore,we classify the irreducible highest weight modules for e d_... 详细信息

关键词： electrical Lie algebra 2-step nilpotent Lie algebra highest weight module

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