One of the largest Ordovician sea-level rises is the Evae transgression,which occurs in the lower part of the Oepikodus evae Biozone,indicative of a late Floian age.Specifically,the characteristics associated with the...One of the largest Ordovician sea-level rises is the Evae transgression,which occurs in the lower part of the Oepikodus evae Biozone,indicative of a late Floian age.Specifically,the characteristics associated with the highstand of this event included:a higher proportion of specimens of the index species O.evae than other species,a diversity acme in the evae Biozone,and a reduction of biogeographic barriers that resulted in a high proportion of species with cosmopolitan distribution.In the present contribution,the pattern of species similarity among Laurentia,Argentine Precordillera,Baltica,Kazakhstania,South China,and Australia is evaluated with a multiple coefficient analysis including only the sections that recorded the highstand of the Evae transgression.Moreover,the effect of possible terrestrial,latitudinal,physicochemical barriers and palaeogeographic distance on the species distribution is statistically analysed.Our results show a global pattern of conodont species distribution that is highly constrained by the tested palaeoenvironmental factors.This suggests that contrary to what was expected for a prominent transgression,faunal barriers did not decrease significantly during the Evae drowning peak.展开更多
High-performance MXene-based polymer nanocomposites are well-suited for various industrial applications owing to their excellent mechanical,thermal,and other properties.However,the fabrication of flame-retardant polym...High-performance MXene-based polymer nanocomposites are well-suited for various industrial applications owing to their excellent mechanical,thermal,and other properties.However,the fabrication of flame-retardant polymer/MXene nanocom-posites remains challenging owing to the limited flame-retardant properties of MXene itself.This study prepared a novel MXene@Ag@PA hybrid material via radiation modification and complexation reaction.This material was used to further enhance the key properties of ethylene-vinyl acetate(EVA),such as its mechanical properties,thermal conductivity,flame retardancy,and electromagnetic shielding.The addition of two parts of this hybrid material increased the thermal conduc-tivity of EVA by 44.2%and reduced its peak exothermic rate during combustion by 30.1%compared with pure EVA.The material also significantly reduced smoke production and increased the residue content.In the X-band,the electromagnetic shielding effectiveness of the EVA composites reached 20 dB.Moreover,the MXene@Ag@PA hybrid material could be used to further enhance the mechanical properties of EVA composites under electron-beam irradiation.Thus,this study contributes to the development of MXene-based EVA advanced materials that are fire-safe,have high strength,and exhibit good electromagnetic shielding performance for various applications.展开更多
基金supported by the Centro de Investigaciones Geol ogicas Aplicadas (CIGEA) (FCEFy NUNC)the Secretaría de Ciencia y Tecnología (Se Cy T-UNC),Universidad Nacional de C ordoba,Argentina。
文摘One of the largest Ordovician sea-level rises is the Evae transgression,which occurs in the lower part of the Oepikodus evae Biozone,indicative of a late Floian age.Specifically,the characteristics associated with the highstand of this event included:a higher proportion of specimens of the index species O.evae than other species,a diversity acme in the evae Biozone,and a reduction of biogeographic barriers that resulted in a high proportion of species with cosmopolitan distribution.In the present contribution,the pattern of species similarity among Laurentia,Argentine Precordillera,Baltica,Kazakhstania,South China,and Australia is evaluated with a multiple coefficient analysis including only the sections that recorded the highstand of the Evae transgression.Moreover,the effect of possible terrestrial,latitudinal,physicochemical barriers and palaeogeographic distance on the species distribution is statistically analysed.Our results show a global pattern of conodont species distribution that is highly constrained by the tested palaeoenvironmental factors.This suggests that contrary to what was expected for a prominent transgression,faunal barriers did not decrease significantly during the Evae drowning peak.
文摘High-performance MXene-based polymer nanocomposites are well-suited for various industrial applications owing to their excellent mechanical,thermal,and other properties.However,the fabrication of flame-retardant polymer/MXene nanocom-posites remains challenging owing to the limited flame-retardant properties of MXene itself.This study prepared a novel MXene@Ag@PA hybrid material via radiation modification and complexation reaction.This material was used to further enhance the key properties of ethylene-vinyl acetate(EVA),such as its mechanical properties,thermal conductivity,flame retardancy,and electromagnetic shielding.The addition of two parts of this hybrid material increased the thermal conduc-tivity of EVA by 44.2%and reduced its peak exothermic rate during combustion by 30.1%compared with pure EVA.The material also significantly reduced smoke production and increased the residue content.In the X-band,the electromagnetic shielding effectiveness of the EVA composites reached 20 dB.Moreover,the MXene@Ag@PA hybrid material could be used to further enhance the mechanical properties of EVA composites under electron-beam irradiation.Thus,this study contributes to the development of MXene-based EVA advanced materials that are fire-safe,have high strength,and exhibit good electromagnetic shielding performance for various applications.
