Based on the anatomical study of leaf cuticles of Cordaites from the Lower Permian Shanxi Formation in Baode of Shanxi, the author analysed the epidermal characters of Cordaites in this area. On the base of the abunda...Based on the anatomical study of leaf cuticles of Cordaites from the Lower Permian Shanxi Formation in Baode of Shanxi, the author analysed the epidermal characters of Cordaites in this area. On the base of the abundant compressions and laboratory studies, the author complemented some new data of the cuticular characters of the speeies Cordaites baodeensis Sun for its study of taxonomy. Meanwhile, the author newly discovered a number of sporopollen fossils associated with the mega-plants of Cordctitales, described 9 species of 6 genera. The palynological data can provide a supplement evidence for defining the age of C. baodeensis and its associated plants to be Early Permian.展开更多
Study on the fossil plants and the palynological assemblage is the basic botanical research on the coal bearing strata. The practice indicate that comprehensive data from the study on the fusinized wood fossil, the ph...Study on the fossil plants and the palynological assemblage is the basic botanical research on the coal bearing strata. The practice indicate that comprehensive data from the study on the fusinized wood fossil, the phyterals and the analysis of dispersed cuticles will effectively improve the level of the study on the coal bearing strata as a whole.展开更多
An angiosperm compression flora is found in Palaeogene from Lanzhou Basin and the cuticular analysis of Populus davidiana Dode in the flora is carefully made. Fur-thermore, the fossil cuticles are compared with the ep...An angiosperm compression flora is found in Palaeogene from Lanzhou Basin and the cuticular analysis of Populus davidiana Dode in the flora is carefully made. Fur-thermore, the fossil cuticles are compared with the epidermal structures of extant Populus leaves growing in different en-vironments, i.e. moist, semimoist, and semiarid to arid cli-matic regions. The present experiments indicate that mature leaves of P. davidiana show leaf size from big to small, leaf cuticles from thick to thin and anticlinal walls of epidermal cells from faintness to clarity along with the increase of lati-tudes of the plant distributions, the climatic variation from moist to arid, the annual precipitation from more to less and the annual mean temperature from high to low. The fossil P. davidiana differs from the specimens collected from Shandan in semiarid to arid climatic regions but closely resembles the Wushan leaves in a semi-moist climatic area in a lot of fea-tures. In a word, the new research may reflect that the flora lives in a semi-moist climatic environment. The present dis-covery of compression of Paleogene Populus davidiana is of great significance to studying vegetation types, climatic and environmental changes during the primal uplifting of the Qinghai-Tibet Plateau.展开更多
Leaf cuticle analysis has long been a powerful tool for fossil plant identification, systematics, and palaeoclimatological recon- struction. In recent decades the application of stomatal frequency data that are relied...Leaf cuticle analysis has long been a powerful tool for fossil plant identification, systematics, and palaeoclimatological recon- struction. In recent decades the application of stomatal frequency data that are relied on precise calculation of stomata on plant fossil cuticles to reconstruct ancient atmospheric CO2 concentration made the preparation of cuticular membrane with sufficient size a critical technique in palaeoclimatological research. However, for plants with originally thin and fragile cuticles, e.g., most deciduous plants, conventional techniques sometimes fail to obtain cuticular membranes with sufficient size, or sometimes unable to recover any. This has largely hampered the usage of fossil cuticle analysis in palaeobotanical and palaeo- climatological research. Here, we describe a new method using clear nail polish as a medium to ＂strengthen＂ the originally thin and fragile cuticles prior to maceration procedures. We demonstrate the method by using middle Eocene Metasequoia fossils that were notorious for the difficulty of recovering large-sized clean cuticular membranes due to their thin and fragile nature. Metasequoia, with well-documented and widely-distributed fossil records since the Late Cretaceous and with a living repre- sentative, 114. glyptostroboides, as a comparative reference, bas been widely used as a model genus for the study of evolution of plants, palaeoclimatological reconstruction, and plant adaptation to climate changes. But its deciduous habit produces thin cuticles and makes the preparation of clean cuticular membranes a tedious process. The new method successfully allows us to recover its delicate cuticular membranes with sufficient sizes for SEM observation and stomatal frequency analysis.展开更多
A lithium-assisted approach has been developed for the exfoliation of pristine graphite, which allows the large-scale preparation of few-layer graphene nanosheets. The process involves an unexpected physical insertion...A lithium-assisted approach has been developed for the exfoliation of pristine graphite, which allows the large-scale preparation of few-layer graphene nanosheets. The process involves an unexpected physical insertion and exfoliafion, and the graphene nanosheets prepared by this method reveal undisturbed sp2-hybridized structures. A possible two-step mechanism, which involves the negative charge being trapped around the edges of the graphite layers and a subsequent lithiation process, is proposed to explain the insertion of lithium inside the graphite interlayers. If necessary, the present exfoliation can be repeated and thinner （single or 2-3 layer） graphene can be achieved on a large scale. This simple process provides an efficient process for the exfoliation of pristine graphite, which might promote the future applications of graphene.展开更多
基金Supported by Project"111"in Jilin University, China (No.B06008)
文摘Based on the anatomical study of leaf cuticles of Cordaites from the Lower Permian Shanxi Formation in Baode of Shanxi, the author analysed the epidermal characters of Cordaites in this area. On the base of the abundant compressions and laboratory studies, the author complemented some new data of the cuticular characters of the speeies Cordaites baodeensis Sun for its study of taxonomy. Meanwhile, the author newly discovered a number of sporopollen fossils associated with the mega-plants of Cordctitales, described 9 species of 6 genera. The palynological data can provide a supplement evidence for defining the age of C. baodeensis and its associated plants to be Early Permian.
文摘Study on the fossil plants and the palynological assemblage is the basic botanical research on the coal bearing strata. The practice indicate that comprehensive data from the study on the fusinized wood fossil, the phyterals and the analysis of dispersed cuticles will effectively improve the level of the study on the coal bearing strata as a whole.
文摘An angiosperm compression flora is found in Palaeogene from Lanzhou Basin and the cuticular analysis of Populus davidiana Dode in the flora is carefully made. Fur-thermore, the fossil cuticles are compared with the epidermal structures of extant Populus leaves growing in different en-vironments, i.e. moist, semimoist, and semiarid to arid cli-matic regions. The present experiments indicate that mature leaves of P. davidiana show leaf size from big to small, leaf cuticles from thick to thin and anticlinal walls of epidermal cells from faintness to clarity along with the increase of lati-tudes of the plant distributions, the climatic variation from moist to arid, the annual precipitation from more to less and the annual mean temperature from high to low. The fossil P. davidiana differs from the specimens collected from Shandan in semiarid to arid climatic regions but closely resembles the Wushan leaves in a semi-moist climatic area in a lot of fea-tures. In a word, the new research may reflect that the flora lives in a semi-moist climatic environment. The present dis-covery of compression of Paleogene Populus davidiana is of great significance to studying vegetation types, climatic and environmental changes during the primal uplifting of the Qinghai-Tibet Plateau.
基金supported by CAS/SAFEA International Partnership Program for Creative Research Teams,the Pilot Project of Knowledge Innovation of CAS (Grant No. KZCX2-YW-105)National Basic Research Program of China (Grant No. 2006CB806400)National Natural Science Foundation of China (Grant Nos. 40402002,40872011)
文摘Leaf cuticle analysis has long been a powerful tool for fossil plant identification, systematics, and palaeoclimatological recon- struction. In recent decades the application of stomatal frequency data that are relied on precise calculation of stomata on plant fossil cuticles to reconstruct ancient atmospheric CO2 concentration made the preparation of cuticular membrane with sufficient size a critical technique in palaeoclimatological research. However, for plants with originally thin and fragile cuticles, e.g., most deciduous plants, conventional techniques sometimes fail to obtain cuticular membranes with sufficient size, or sometimes unable to recover any. This has largely hampered the usage of fossil cuticle analysis in palaeobotanical and palaeo- climatological research. Here, we describe a new method using clear nail polish as a medium to ＂strengthen＂ the originally thin and fragile cuticles prior to maceration procedures. We demonstrate the method by using middle Eocene Metasequoia fossils that were notorious for the difficulty of recovering large-sized clean cuticular membranes due to their thin and fragile nature. Metasequoia, with well-documented and widely-distributed fossil records since the Late Cretaceous and with a living repre- sentative, 114. glyptostroboides, as a comparative reference, bas been widely used as a model genus for the study of evolution of plants, palaeoclimatological reconstruction, and plant adaptation to climate changes. But its deciduous habit produces thin cuticles and makes the preparation of clean cuticular membranes a tedious process. The new method successfully allows us to recover its delicate cuticular membranes with sufficient sizes for SEM observation and stomatal frequency analysis.
基金This work was supported by the National Natural Science Foundation of China （No. 51222104） and the Fundamental Research Funds for the Central Universities.
文摘A lithium-assisted approach has been developed for the exfoliation of pristine graphite, which allows the large-scale preparation of few-layer graphene nanosheets. The process involves an unexpected physical insertion and exfoliafion, and the graphene nanosheets prepared by this method reveal undisturbed sp2-hybridized structures. A possible two-step mechanism, which involves the negative charge being trapped around the edges of the graphite layers and a subsequent lithiation process, is proposed to explain the insertion of lithium inside the graphite interlayers. If necessary, the present exfoliation can be repeated and thinner （single or 2-3 layer） graphene can be achieved on a large scale. This simple process provides an efficient process for the exfoliation of pristine graphite, which might promote the future applications of graphene.
