Thermoelectric coolers utilizing the Peltier effect have dominated the field of solid-state cooling but their efficiency is hindered by material limitations.Alternative routes based on the Thomson and Nernst effects o...Thermoelectric coolers utilizing the Peltier effect have dominated the field of solid-state cooling but their efficiency is hindered by material limitations.Alternative routes based on the Thomson and Nernst effects offer new possibilities.Here,we present a comprehensive investigation of the thermoelectric properties of 1T-TiSe_(2),focusing on these effects around the charge density wave transition(≈200 K).The abrupt Fermi surface reconstruction associated with this transition leads to an exceptional peak in the Thomson coefficient of 450μVK^(-1) at 184 K,surpassing the Seebeck coefficient.Furthermore,1T-TiSe_(2) exhibits a remarkably broad temperature range(170-400 K)with a Thomson coefficient exceeding 190μV K^(-1),a characteristic highly desirable for the development of practical Thomson coolers with extended operational ranges.Additionally,the Nernst coefficient exhibits an unusual temperature dependence,increasing with temperature in the normal phase,which we attribute to bipolar conduction effects.The combination of solid-solid pure electronic phase transition to a semimetallic phase with bipolar transport is identified as responsible for the unusual Nernst trend and the unusually large Thomson coefficient over a broad temperature range.展开更多
The Joule-Thomson effect is one of the important thermodynamic properties in the system relevant to gas switching reforming with carbon capture and storage(CCS). In this work, a set of apparatus was set up to determin...The Joule-Thomson effect is one of the important thermodynamic properties in the system relevant to gas switching reforming with carbon capture and storage(CCS). In this work, a set of apparatus was set up to determine the Joule-Thomson effect of binary mixtures(CO_(2)+ H_(2)). The accuracy of the apparatus was verified by comparing with the experimental data of carbon dioxide. The Joule-Thomson coefficients(μ_(JT)) for(CO_(2)+ H_(2)) binary mixtures with mole fractions of carbon dioxide(x_(CO_(2))= 0.1, 0.26, 0.5,0.86, 0.94) along six isotherms at various pressures were measured. Five equations of state EOSs(PR,SRK, PR, BWR and GERG-2008 equation) were used to calculate the μ_(JT)for both pure systems and binary systems, among which the GERG-2008 predicted best with a wide range of pressure and temperature.Moreover, the Joule-Thomson inversion curves(JTIC) were calculated with five equations of state. A comparison was made between experimental data and predicted data for the inversion curve of CO_(2). The investigated EOSs show a similar prediction of the low-temperature branch of the JTIC for both pure and binary systems, except for the BWRS equation of state. Among all the equations, SRK has the most similar result to GERG-2008 for predicting JTIC.展开更多
文摘通过传统形态分类结合DNA条形码方法对寄生性天敌伲姬小蜂属Necremnus Thomson(姬小蜂科Eulophidae)进行整合分类研究,查明东帕米尔高原伲姬小蜂属资源状况,为该属物种的快速准确鉴定以及生物学、系统发育等研究奠定基础。于2021-2023年以网扫和黄盘诱集为主要采集方法获得东帕米尔高原的伲姬小蜂属标本;在数码体视显微镜下观察测量标本的形态特征,进行形态分类学研究;在传统形态鉴定的基础上,利用无损伤提取法提取物种基因组DNA,获得COI序列,并与数据库中该属物种COI序列比对,分析其碱基组成和遗传距离,基于最大似然法构建系统发育树,进行系统发育分析。本研究发现东帕米尔高原伲姬小蜂属5种,其中一个新种—暗黑伲姬小蜂Necremnus nigra Xi&Hu, sp.nov.,对该新种进行了形态描述,并提供了形态特征图。DNA条形码分析结果表明,暗黑伲姬小蜂与潜叶蛾伲姬小蜂亲缘关系更近。
基金S.A.and M.Z.acknowledge support by NSF,grant number 2230352S.S.D.acknowledges support from the UVA Research Innovation AwardK.S.D.and D.L.work on TMDs has been supported by National Science Foundation Grant No.221949.
文摘Thermoelectric coolers utilizing the Peltier effect have dominated the field of solid-state cooling but their efficiency is hindered by material limitations.Alternative routes based on the Thomson and Nernst effects offer new possibilities.Here,we present a comprehensive investigation of the thermoelectric properties of 1T-TiSe_(2),focusing on these effects around the charge density wave transition(≈200 K).The abrupt Fermi surface reconstruction associated with this transition leads to an exceptional peak in the Thomson coefficient of 450μVK^(-1) at 184 K,surpassing the Seebeck coefficient.Furthermore,1T-TiSe_(2) exhibits a remarkably broad temperature range(170-400 K)with a Thomson coefficient exceeding 190μV K^(-1),a characteristic highly desirable for the development of practical Thomson coolers with extended operational ranges.Additionally,the Nernst coefficient exhibits an unusual temperature dependence,increasing with temperature in the normal phase,which we attribute to bipolar conduction effects.The combination of solid-solid pure electronic phase transition to a semimetallic phase with bipolar transport is identified as responsible for the unusual Nernst trend and the unusually large Thomson coefficient over a broad temperature range.
基金supported by the National Natural Science Foundation of China (21878056)Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology (2019Z002)。
文摘The Joule-Thomson effect is one of the important thermodynamic properties in the system relevant to gas switching reforming with carbon capture and storage(CCS). In this work, a set of apparatus was set up to determine the Joule-Thomson effect of binary mixtures(CO_(2)+ H_(2)). The accuracy of the apparatus was verified by comparing with the experimental data of carbon dioxide. The Joule-Thomson coefficients(μ_(JT)) for(CO_(2)+ H_(2)) binary mixtures with mole fractions of carbon dioxide(x_(CO_(2))= 0.1, 0.26, 0.5,0.86, 0.94) along six isotherms at various pressures were measured. Five equations of state EOSs(PR,SRK, PR, BWR and GERG-2008 equation) were used to calculate the μ_(JT)for both pure systems and binary systems, among which the GERG-2008 predicted best with a wide range of pressure and temperature.Moreover, the Joule-Thomson inversion curves(JTIC) were calculated with five equations of state. A comparison was made between experimental data and predicted data for the inversion curve of CO_(2). The investigated EOSs show a similar prediction of the low-temperature branch of the JTIC for both pure and binary systems, except for the BWRS equation of state. Among all the equations, SRK has the most similar result to GERG-2008 for predicting JTIC.
