Jellyfish blooms occur worldwide and have resulted in serious problems in tourism,fisheries,coastal industries,and the marine ecosystem.The life cycle of scyphozoan jellyfish consists of a pelagic medusa stage and a b...Jellyfish blooms occur worldwide and have resulted in serious problems in tourism,fisheries,coastal industries,and the marine ecosystem.The life cycle of scyphozoan jellyfish consists of a pelagic medusa stage and a benthic polyp stage.Success of asexual reproduction of the polyps determines directly the number of medusae;thus,the polyp stage is the key to understanding the population dynamics of medusae.Nemopilema nomurai,Aurelia coerulea,and Rhopilema esculentum are three scyphozoan jellyfish commonly inhabit in Chinese coastal waters.Polyps of A.coerulea are easily visible,while those of N.nomurai and R.esculentum remain yet to be found in the wild.However,distribution of the medusa indicates that the polyps of all three species may occur together.To evaluate the distribution pattern of polyps of the three species and explore intraguild predation by the polyps,we conducted a laboratory experiment that considered the attachment sequence and size relationship of calyx diameter of the polyps.We found that the polyps of A.coerulea preyed on polyps of the other two species in all treatments,except when polyps of R.esculentum were bigger than those of A.coerulea.The polyps of R.esculentum preyed on the polyps of N.nomurai only when polyps of R.esculentum attached first and were bigger than those of N.nomurai.Colonies of N.nomurai polyps were rarely found in the places inhabited by A.coerulea polyps.In addition,A.coerulea polyps are known to inhabit at depths of less than 20 m in coastal sea,thus,we speculate that N.nomurai polyp colonies might occur at depths of more than 20 m.Therefore,our finding that polyps of A.coerulea aggressively preyed on polyps of other species may help understand other such systems of jellyfish bloom in the world.展开更多
In this paper, we prove the existence of a limit cycle for a given system of differential equations corresponding to an asymmetrical intraguild food web model with functional responses Holling type II for the middle a...In this paper, we prove the existence of a limit cycle for a given system of differential equations corresponding to an asymmetrical intraguild food web model with functional responses Holling type II for the middle and top predators and logistic grow for the (common) prey. The existence of such limit cycle is guaranteed, via the first Lyapunov coefficient and the Andronov-Hopf bifurcation theorem, under certain conditions for the parameters involved in the system.展开更多
This study explores the adsorption and reac-tion of methanol on the CeO_(2)(111)and Ni/CeO_(2)(111)surfaces,highlighting the es-sential role of metal-support interaction in methanol decomposition by a synergistic ap-p...This study explores the adsorption and reac-tion of methanol on the CeO_(2)(111)and Ni/CeO_(2)(111)surfaces,highlighting the es-sential role of metal-support interaction in methanol decomposition by a synergistic ap-proach encompassing synchrotron radiation photoemission spectroscopy,X-ray photo-electron spectroscopy,infrared reflection and absorption spectroscopy,and temperature-programmed desorption.Our findings reveal that Ni deposited on the CeO_(2)(111)surface,followed by annealing to 700 K,leads to the formation of Ce-O-Ni mixed oxide as the dominant phase.The Ni^(2+)species facilitate the methoxy decomposition into CO and H_(2)within 300-430 K,with a small amount of formalde-hyde also forming at the edge sites of ceria.Additionally,some methoxy adsorbed on the bare CeO_(2)surface migrates to the Ce-O-Ni mixed oxide,where they decompose into CO and H_(2)at 500-600 K,accompanied by a portion of the methoxy interacting with ceria to generate formaldehyde.Upon exposure to methanol at 500 K,the Ni^(2+)species are reduced to metallic Ni^(0),alongside the formation of coke and Ni_(3)C,ultimately resulting in catalyst deactivation.However,reintroducing O_(2)reactivates these sites by oxidizing metallic Ni^(0)and Ni_(3)C species.This study highlights the pivotal role of metal-support interaction in promoting oxygen trans-fer from ceria to Ni,thereby enhancing methoxy decomposition and significantly improving the performance of Ni-based catalysts for methanol decomposition into CO and H_(2).展开更多
基金Supported by the National Key Research and Development Program of China(No.2017YFC1404405)the Taishan Scholar Climbing Plan to Sun Song,the Shandong Joint Fund for Marine Ecology and Environmental Sciences(No.U1606404)the Aoshan Science and Technology Innovation Project(No.2016ASKJ02-2)。
文摘Jellyfish blooms occur worldwide and have resulted in serious problems in tourism,fisheries,coastal industries,and the marine ecosystem.The life cycle of scyphozoan jellyfish consists of a pelagic medusa stage and a benthic polyp stage.Success of asexual reproduction of the polyps determines directly the number of medusae;thus,the polyp stage is the key to understanding the population dynamics of medusae.Nemopilema nomurai,Aurelia coerulea,and Rhopilema esculentum are three scyphozoan jellyfish commonly inhabit in Chinese coastal waters.Polyps of A.coerulea are easily visible,while those of N.nomurai and R.esculentum remain yet to be found in the wild.However,distribution of the medusa indicates that the polyps of all three species may occur together.To evaluate the distribution pattern of polyps of the three species and explore intraguild predation by the polyps,we conducted a laboratory experiment that considered the attachment sequence and size relationship of calyx diameter of the polyps.We found that the polyps of A.coerulea preyed on polyps of the other two species in all treatments,except when polyps of R.esculentum were bigger than those of A.coerulea.The polyps of R.esculentum preyed on the polyps of N.nomurai only when polyps of R.esculentum attached first and were bigger than those of N.nomurai.Colonies of N.nomurai polyps were rarely found in the places inhabited by A.coerulea polyps.In addition,A.coerulea polyps are known to inhabit at depths of less than 20 m in coastal sea,thus,we speculate that N.nomurai polyp colonies might occur at depths of more than 20 m.Therefore,our finding that polyps of A.coerulea aggressively preyed on polyps of other species may help understand other such systems of jellyfish bloom in the world.
文摘In this paper, we prove the existence of a limit cycle for a given system of differential equations corresponding to an asymmetrical intraguild food web model with functional responses Holling type II for the middle and top predators and logistic grow for the (common) prey. The existence of such limit cycle is guaranteed, via the first Lyapunov coefficient and the Andronov-Hopf bifurcation theorem, under certain conditions for the parameters involved in the system.
基金financially supported by the National Key R&D Program of China(2023YFA1509103)the National Natural Science Foundation of China(Nos.22272157,21872131,22106085,and U1932214)。
文摘This study explores the adsorption and reac-tion of methanol on the CeO_(2)(111)and Ni/CeO_(2)(111)surfaces,highlighting the es-sential role of metal-support interaction in methanol decomposition by a synergistic ap-proach encompassing synchrotron radiation photoemission spectroscopy,X-ray photo-electron spectroscopy,infrared reflection and absorption spectroscopy,and temperature-programmed desorption.Our findings reveal that Ni deposited on the CeO_(2)(111)surface,followed by annealing to 700 K,leads to the formation of Ce-O-Ni mixed oxide as the dominant phase.The Ni^(2+)species facilitate the methoxy decomposition into CO and H_(2)within 300-430 K,with a small amount of formalde-hyde also forming at the edge sites of ceria.Additionally,some methoxy adsorbed on the bare CeO_(2)surface migrates to the Ce-O-Ni mixed oxide,where they decompose into CO and H_(2)at 500-600 K,accompanied by a portion of the methoxy interacting with ceria to generate formaldehyde.Upon exposure to methanol at 500 K,the Ni^(2+)species are reduced to metallic Ni^(0),alongside the formation of coke and Ni_(3)C,ultimately resulting in catalyst deactivation.However,reintroducing O_(2)reactivates these sites by oxidizing metallic Ni^(0)and Ni_(3)C species.This study highlights the pivotal role of metal-support interaction in promoting oxygen trans-fer from ceria to Ni,thereby enhancing methoxy decomposition and significantly improving the performance of Ni-based catalysts for methanol decomposition into CO and H_(2).
