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Pliocene taxodiaceous fossil wood from southwestern Ukraine and its palaeoenvironmental implications

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Journal of Palaeogeography 2013年第4期2卷 362-368页

作者： Yi Tiemei LI ChengSen Svetlana Syabryaj Beijing Institute of Science and Technology Information Laboratory of Systematic and Evolutionary Botany Institute of BotanyChinese Academy of Sciences Institute of Geological Sciences National Academy of Sciences of Ukraine

Mineralized wood collected from Late Pliocene strata near Gorbki village in the Transcarpathian region of Beregovo Kholmogor’e in southwestern Ukraine was anatomically studied and identified.The wood possesses distinctive anatomical features and has distinct growth rings with an abrupt transition from early-to late-wood.Wood consists of tracheids with 1-3 seriate,dominating bi-seriate,opposite pits on the radial walls and taxodioid crossfield pitting,indentures present.Rays are uni-seriate and 1 to 73 cells high.Ray parenchyma horizontal walls thin and smooth.Axial parenchyma distributed in early-and late-wood and is solitary and diffuse,with end walls nearly smooth or slightly nodular.The combination of features observed in the wood indicates it belongs to the conifer family Taxodiaceae and is most similar to modern Sequoia and assigned to the fossil genus Sequoioxylon.Comparison with species of Sequoioxylon show it is most similar to Sequoioxylon burejense,but ray tracheids were not found in our specimens.We describe the specimens here as Sequoioxylon cf.***.burejense noting this similarity.Extant Sequoia is distributed in the northern California coastal forest eco-region of northern California and southern Oregon in the United States where they usually grow in a unique environment with heavy seasonal precipitation(2500 mm annually),cool coastal air and fog drip.This study supplies magafossil evidence of Sequoioxylon as an element of the Late Pliocene forest community in Ukraine and indicates a climate with heavy seasonal precipitation and fog drip.

关键词： Late Pliocene gymnosperm conifer Sequoioxylon fossil wood Ukraine

A Review on the Taxonomic,Evolutionary and Phytogeographic Studies of the Lotus Plant(Nelumbonaceae:Nelumbo)

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Acta Geologica Sinica(English Edition) 2014年第4期88卷 1252-1261页

作者： li Ya Popova SVETLANA YAO Jianxin LI ChengSen Institute of Geology Chinese Academy of Geological Sciences Key Laboratory of Stratigraphy and Paleontology Ministry of Land and Resources of the People's Republic of China State Key Laboratory of Systematic and Evolutionary Botany Institute of BotanyChinese Academy of Sciences Laboratory of Palaeobotany Komarov Botanical InstituteRussian Academy of Sciences

Nelumbo Adans. （Nelumbonaceae） is an important member of the early-diverging eudicots. It contains two extant species： N. nucifera Gaertn. （the Sacred lotus）, distributed in Asia and Australia and N. lutea Willd. （the American lotus）, occurring in North America. This paper reviews the taxonomic, evolutionary and phytogeographic studies of the genus Nelumbo, and also raises scientific questions about it in further paleobotanic research. There are about 30 fossil species of Nelumbo established since the Early Cretaceous. Based on fossil studies, the ancestors of the extant N. nucifera and N. lutea are respectively considered to be N. protospeciosa from the Eocene to Miocene of Eurasia, and N. protolutea from the Eocene of North American. However, molecular systematic studies indicate that N. nucifera and N. lutea are probably split from a common ancestor during the Late Miocene to Early Pliocene, or even the Pleistocene, rather than separate relicts from extinct species on different continents. The characters of lotus stomatal development, seedling morphology as well as its flowering, pollination and fertilization in air reveal that it evolves from the land plants. Fossil data of Nelumbo indicates that the genus first occurs in mid-latitude area of Laurasia in the Early Cretaceous, then becomes widespread in North America and Eurasia and expands into Africa and South America during the Late Cretaceous; the genus probably colonizes the Indian Subcontinent from Asia during the Early Eocene after the collision of India and the Asian plates; the genus becomes extinct in Europe, but survives in Asia and North America during the Quaternary Ice Age, and later forms the present East Asia and North Australia-North America disjunctive distribution.

关键词： taxonomy evolution phytogeography Nelumbo Nelumbonaceae

Early Miocene Mosses from Weichang, North China, and their Environmental Significance

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Acta Geologica Sinica(English Edition) 2013年第6期87卷 1508-1519页

作者： GUO Caiqing YAO Jianxin WU Pengcheng LI ChengSen Key Laboratory of Stratigraphy and Paleontology Institute of Geology Chinese Academy of Geological Sciences State Key Laboratory of Systematic and Evolutionary Botany Institute of Botany Chinese Academy of Sciences

Twenty-seven moss specimens collected from the Guangfayong section （Early Miocene,22.1 Ma） of the Weichang District,North China were investigated in the present study.Based on the morphological and anatomical features of gametophytes,all specimens were found to belong to three species：Leptodictyum riparium,Drepanocladus subtrichophyllus sp.nov.,and Amblystegium varium,all of which belong to the family Amblystegiaceae.The microhabitats and living environments of fossil mosses were also investigated based on comparison with living mosses.The results suggest that these mosses grew primarily at the edges of rivers,streams,and lakes and favored being submerged in streams or lakes in the Weichang District in the Early Miocene.

关键词： fossil mosses Amblystegiaceae Early Miocene paleoenvironment and paleoclimate North China

A Low-Complexity PTS Based on Greedy and Genetic Algorithm for OFDM Systems

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Chinese Journal of Electronics 2015年第4期24卷 857-861页

作者： LUO Renze ZHANG chengsen NIU Na li Rui State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum University University of Electronic Science and Technology of China

Partial transmit sequence(PTS) is one of effective technique to reduce high Peak-to-average power ratio(PAPR) in Orthogonal frequency division multiplexing(OFDM) system. However, the complexity of Original PTS(O-PTS) increases exponentially with the number of sub-blocks. To reduce the computational complexity while still offering a lower PAPR, a new PTS method is proposed to search for suboptimal rotating vectors in this paper. In the proposed method, the candidate rotation vectors are generated based on greedy and genetic algorithm.We also combine the proposed method and the superimposed training sequence method to get a further PAPR reduction. The theory and simulations results show that the proposed method can achieve better PAPR reduction and significantly reduce the computational complexity.

关键词： PTS PAPR reduction OFDM Suboptimal rotating vectors

Natural traps of spores and pollen grains from the region surrounding Wenbi Reservoir, Yunnan, China

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科学通报 2013年第S1期58卷 162-168页

作者： SONG XiaoYan BERA Subir YAO YiFeng BLACKMORE Stephen LI ChengSen State Key Laboratory of Systematic and Evolutionary Botany Institute of BotanyChinese Academy of Sciences Shanxi Agricultural University Department of Botany University of Calcutta Royal Botanic Garden Edinburgh

We did a comparative analysis of pollen and spores from five kinds of natural pollen traps at Wenbi Reservoir, northwest Yunnan, China. The natural traps were the surface soil, ground inhabiting mosses, spider webs, tree bark and moss/lichen on trees. These traps showed qualitative and quantitative variations in the pollen and spore spectra. The palynomorphs recovered from the soil samples of trees and shrubs ranged from 90.54% to 95.98% of the total counts. These counts were higher than counts from ground mosses(53.13%–81.66%), spider webs(61.71%), bark samples(53.8%) and moss/lichen on trees(50%–53.6%). The result of pollen/spore analysis showed that surface soil, ground mosses and spider webs better reflect the local vegetation compared with tree bark or moss/lichen on trees.

关键词： natural pollen traps Wenbi Reservoir Yunnan China vegetation

New plants of Gnetales from Early Cretaceous of China, and its bearing on the early evolution of Ephedraceae and Welwitschiaceae in Gnetales

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科学通报 2013年第S1期58卷 200-209页

作者： liU HaiMing FERGUSON David K. LI ChengSen WANG YuFei Beijing Museum of Natural History Department of Paleontology University of Vienna Institute of Botany Chinese Academy of Sciences

The Gnetales are a higher group of Gymnosperms, but our current knowledge of the morphology of the early Gnetales is lacking. Most known specimens are fragmentary, which makes it difficult to elucidate the geological history and the early diversity and evolution of the group. New well-preserved specimens have been discovered in liaoning, north China, and a detailed morphological study was carried out. The material belongs to three new genera: Spinobractea lanceoleta gen. et sp. nov., Latibractea divisa gen. et sp. nov. and Constrobilus ovata gen. et sp. nov. The record of the Ephedraceae can be traced back to the Jurassic. The Ephedraceae were quite successful in the Cretaceous, and the plant types and the environment that they inhabited shown that the Cretaceous plants were much more varied than their living relatives. However, some types became extinct, and some features were lost. The record of the Welwitschiaceae can be traced back to the Triassic. Features of the leaf venation and the seeds are the primary features used for recognition of this family in both living and fossil plants. These features are so conservative that they have shown almost no major changes since the Triassic.

关键词： Early Cretaceous north China Spinobractea Latibractea Constrobilus

Pollen morphology in Saxifraga(Saxifragaceae) from Ny-Alesund, Svalbard, Arctic, and its taxonomic significance

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Advances in Polar Science 2014年第2期25卷 105-112页

作者： YAO Yifeng Bera Subir Ferguson David Kay LI ChengSen State Key Laboratory of Systematic and Evolutionary Botany Institute of Botany Chinese Academy of Sciences Department of Botany University of Calcutta Department of Paleontology University of Vienna

Pollen morphology of eight species of Saxifraga, i.e.S, cespitosa, S. oppositifolia, S. cernua, S. nivalis, S. aizoides, S. rivularis, S. hieraciifolia, and S. hirculus, collected from Ny-Alesund, Svalbard, Arctic was examined using light and scanning electron microscopy. Pollen grains of Saxifraga species are subprolate or prolate, 3-colpate, 15.4-44.4 μm in the polar axis, 11.4 34.6 μm in the equatorial axis, and show a P/E ratio 1.19-1.40. On the basis of exine ornamentation, four pollen types, viz., the S. oppositifolia type （striate without scabrae on the muff）, S. cernua type （striate with scabrae on the muri）, S. nivalis type （microreticulate and operculum absent）, and S. cespitosa type （microechinate and operculum present）, were recognized. Hierarchical cluster analysis of the pollen morphological characters indicated that pollen morphology supports the infrageneric classification of the genus Saxifraga.

关键词： Arctic Ny-Alesund pollen morphology Saxifraga Svalbard

Total Synthesis of UCS1025A via Tandem Carbonylative Stille Cross Coupling and Diels-Alder Reactiont

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Chinese Journal of Chemistry 2023年第22期41卷 3019-3024页

作者： chengsen Cui Mingi Dai Deparment of Chemistry and Center for Cancer Research Purdue University West Lfaytte IN 47907United States Department of Chemistry Emory UniversityAtlantaGA 30322United States

We report an efficient and convergent strategy for the total synthesis of UCS1025A and its diastereomer tetra-epi-UCS1025A.Ucs1025A is a representative member of the naturally occurring pyrrolizidinone polyketides,from which members with potent antibacterial,antifungal,and anticancer activities have been identified.Our approach features a tandem carbonylative Stille cross coupling and Diels-Alder reaction to forge a key C-C bond and build the trans-decalin system.This tandem process utilizes carbon monoxide as a one-carbon linchpin to stitch a vinyl triflate and a vinylstannane together and form the desired enone moiety for the subsequent intramolecular Diels-Alder cyclization.Our synthesis also provides a versatile approach for the synthesis of other related pyrrolizidinone-containing polyketides.

关键词： Natural products Total synthesis UCS1025A Carbonylation Diels-Alder reaction Tandem reaction

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前路心磨大量提取高精度面粉的工艺措施

现代面粉工业 2023年第2期37卷 3-5页

作者：李成森山东淄博制粉工程有限公司山东淄博255100

由于工艺配置、操作等原因,一些企业有好小麦却生产不出好面粉,或者高精度面粉的提取率很低,其一个重要的原因就是好料后推,货料重复研磨,违背了高精度面粉生产的基本原则,前路心磨不能大量提取高精度面粉。从研磨、筛理、清粉、操作指... 详细信息

由于工艺配置、操作等原因,一些企业有好小麦却生产不出好面粉,或者高精度面粉的提取率很低,其一个重要的原因就是好料后推,货料重复研磨,违背了高精度面粉生产的基本原则,前路心磨不能大量提取高精度面粉。从研磨、筛理、清粉、操作指标以及技术参数等方面阐述在前路心磨提取高精度面粉的工艺措施,以期达到提高面粉质量和出粉率的目的。

关键词：高精度面粉质量出率前路心磨细麸屑