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Direct evidence of transformation from smectite to palygorskite:TEM investigation

Science china Earth Sciences 2004年第11期47卷 985-994页

作者： CHEN Tianhu1,,XU Huifang2,LU Anhuai3,XU Xiaochun1,PENG Shuchuan1 2 &YUE Shucang1 1.College of Resources and Environmental Engineering,Hefei university of Technology,Hefei 230009,china 2.department of geology and Geophysics,university of Wisconsin,Madison,WI53706,USA 3.department of geology,peking university,beijing 100871,china Correspondence should be addressed to Chen Tianhu(email: tianhu@*** or cth168@***) College of Resources and Environmental Engineering Hefei University of Technology Hefei China department of geology and Geophysics University of Wisconsin Madison USA department of geology Peking University Beijing China

Palygorskite clays sampled from palygorskite clay deposits in Jiangsu and Anhui provinces were investigated by transmission electron microscopy (TEM). Many intergrowth phenomena of special ultra-microstructure between smectite and palygorskite were found. The ultra-microstructure indicates that palygorsite fiberrous crystals grow along (001) of primary smectite through structural transformation and decomposition of the primary smectite. According to field investigation and X-ray diffraction (XRD) analyses, the transformation mechanism and process can be described as: formation of smectite from basalt weathering deposited in localiza- tion basin; evaporation of lake water in aridity environment causing pH increase and concentra- tion of magnesium ion in interstice water of sediment smectite in the lake basin. Under alkaline conditions, magnesium ion occupied interlayer positions of the smectite. Because of the misfit between magnesium octahedral sheet and smectite layer, magnesium ion interaction with smec- tite layers caused the smectite to transform into palygorskite, and resulted in the formation of smectite and palygorskite complex particulates, and even smaller secondary smectite crystal plates. The transformation of smectite structure resulted in the formation of nanometer minerals with large specific surface area and excellent property of physics and chemistry in smec- tite-palygorskite mixing clay. The results from TEM investigation are important for understanding properties of palygorskite clay and application.

关键词： palygorskite, smectite, transmission electron microscopy, X-ray diffraction, nanometer mineralogy.

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THE PHYSICAL ENTROPY OF SINGLE CONSERVATION LAWS

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Journal of Computational Mathematics 1998年第5期16卷 437-444页

作者： (department of Mathematics, peking university, beijing 100871, china) 北京大学数学系北京

By means of the comparisons with the formulas in statistical mechanics and thermodynamics, in this paper it is demonstrated that for the single conservation law partial derivative(t)u + partial derivative(x)f(u) = 0, if the flux function f(u) is convex (or concave), then, the physical entropy is S = -f(u); Furthermore, if we assume this result can be generalized to any f(u) with two order continuous derivative, from the thermodynamical principle that the local entropy production must be non-negative, one entropy inequality is derived, by which the O.A. Olejnik's famous E- condition can be explained successfully in physics.

关键词： conservation laws entropy entropy production

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THE FUNCTION d_k(n) AT CONSECUTIVE INTEGERS

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Chinese Annals of Mathematics,Series B 1999年第4期20卷 473-478页

作者： MENG ZAIZHAO(department of Mathematics, peking university, beijing 100871, china) department of Mathematics Peking University Beijing 100871 China

Let dk(n) denote the k-fold iterated divisor function (k ≥ 2). It is proved that for sufficiently large x) dk(n) = dk(n + 1) holds for >> x(log log x)-3 integers n ≤x.

关键词： Divisor function Multiplicative function Congruence

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Phytolith assemblages and their implications from cal soils of Yingyang site in Dengfeng County, Henan Province

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Chinese Science Bulletin 1997年第1期42卷 57-61页

作者： JIANG Qinhuadepartment of geology, peking university, beijing 100871, china Depmment of geology Peking University Beijing China

THE central plain of china has been considered as the cradle of the Chinese people, as is indicated by the abundant archaeological finds during the last 60 years. As a supplementary study to the archaeological excavation at Yingyang site of Dengfeng County, phytolith analysis was carried out. The Yingyang neolithic site is located in the south of the North china Plain and at the upper reaches of the Yinghe River, which belongs to the Huaihe drainage system, within

关键词： Yingyang site archaeological soils phytolith analysis paleoenvironment.

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Neuroimaging studies of self-reflection

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Progress in Natural Science:Materials International 2004年第4期14卷 10-16页

作者： ZHU Ying(department of Psychology, peking university, beijing 100871, china) department of Psychology Peking University Beijing 100871 China

This paper reviews some basic findings and methodological issues in neuroimaging studies of self-referential processing. As a general rule, making judgments about one’s self, inclusive of personality trait adjectives or current mental states (person’ s preferences, norms, aesthetic values and feeling) uniformly generates medial prefrontal activations, regardless of stimulus materials (words or pictures) and modality (visual or auditory). Cingulate activations are also observed in association with most self-referential processing. Methodological issues include treating self-referential processing as either representing one’s own personality traits or representing one’s own current mental states. Finally, self-referential processing could be considered as implement of "I think therefore I am" approach to neuroimaging the self.

关键词： self self-referential processing medial prefrontal cortex cingulate brain image.

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Anatomical reinvestigation of Archaeopteris macilenta from the Upper Devonian(Frasnian) of South china

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Journal of Systematics and Evolution 2011年第6期49卷 590-597页

作者： Yun GUO De-Ming WANG(Key Laboratory of Orogenic Belts and Crustal Evolution,department of geology,peking university,beijing 100871,china) ( Key Laboratory of Orogenic Belts and Crustal Evolution Department of Geology Peking University Beijing 100871 China)

Archaeopteris macilenta is one of the most widespread plants in the Late *** on fossils from the Frasnian Huangjiadeng Formation,Yichang District of Hubei Province,for the first time we study in detail the anatomy of this progymnosperm plant in South *** axes are protostelic with three xylem sympodia and lack secondary *** axes are eustelic,bearing eight sympodia and a thin band of secondary *** symmetrical sympodia of mesarch primary xylem produce traces of appendages in a spiral *** macilenta and ***(***)are dominant in the Frasnian and Famennian,*** with these two species from other tectonic plates indicate consistent stelar *** spread,continuous occurrence,and identical anatomy during the Late Devonian indicate that Archaeopteris survived the Frasnian-Famennian extinction *** this time,endemic genera and cosmopolitan taxa,including Archaeopteris,suggest the palaeogeographic isolation of South china and certain associations with other plates.

关键词： anatomy Archaeopteris Late Devonian palaeogeography progymnosperms South china.

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Oblique Derivative Problems for Second OrderNonlinear Equations of Mixed Type inMultiply Connected Domains

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Communications in Nonlinear Science and Numerical Simulation 1999年第4期4卷 281-284页

作者： Guochun WEN(department of Mathematics, peking university, beijing 100871, china) department of Mathematics Peking University Beijing 100871 China

1FormulationoftheProblemLetDbeNconnectedboundeddomaininthecomplexplaneCwiththeboundaryNZNOD=WUL,wherer=ZrjEn（00},L=ULi’andrhastheendj=1j=1poiatsal=0 详细信息

1FormulationoftheProblemLetDbeNconnectedboundeddomaininthecomplexplaneCwiththeboundaryNZNOD=WUL,wherer=ZrjEn（00},L=ULi’andrhastheendj=1j=1poiatsal=0

关键词： oblique derivative problems quasinonlinear equations of mixed type mul-tiply connected domains.

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Electrical Properties of Expanded Graphite Intercalation Compounds

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Journal of Materials Science & Technology 2001年第3期17卷 371-374页

作者： Xiuyun CHUAN department of geology, peking university, beijing 100871, china Daizhang CHEN and Xunruo ZHOU department of Materials Science, china university of Geosciences, beijing 100083, china E-mail: cxyljhcj@*** Dept. of Geol. Beijing Univ. Beijing 100871 China

The intercalation compounds of CuCl2 were synthesized with expanded graphite, whose magnitude of the electrical conductivity is about 10(3)S(.)cm(-1). Their electrical conductivity is 3 similar to6 times as high as that of the expanded graphite, and about 10 times as high as that of GIC made of the non-expanded graphite. The microanalysis results of chemical compounds by X-ray energy spectrum scanning of TEM testified that the atomic ratio of chloride and cupric is nonstoichoimetric. The multivalence and exchange of electrovalence of the cupric ion was confirmed by the XPS-ESCA. Vacancy of chlorine anion increases the concentration of charge carrier. The special stage structure, made of graphite and chloride, produces a weak chemical bond belt and provides a carrier space in the direction of GIC layer. These factors develop the electrical properties.

关键词： In Ph Electrical Properties of Expanded Graphite Intercalation Compounds Graphite ESCA

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ESTIMATING EXTREME-VALUE INDEX FROM RECORDS

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Chinese Annals of Mathematics,Series B 1998年第4期19卷 499-510页

作者： QI YONGCHENG (department of Probability & Statistics, peking university, beijing 100871, china.) 北京大学概率统计系北京

This paper constructs from the record values an estimator of the extreme-value index. It is proved that the estimator is consistent in the domain of attraction of extremesvalue distributions, and that under very mild ... 详细信息

关键词： Record Extreme value distribution Estimator Consistency Asymptotic normality

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Progress in cognitive neuroscientific studies of visual awareness

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Progress in Natural Science:Materials International 2009年第2期19卷 145-152页

作者： Qi Li,Haiyan Geng department of Psychology,peking university,beijing 100871,china department of Psychology Peking University Beijing 100871 China

The psychological and neural mechanisms of consciousness are among the most baffling problems in cognitive neuroscience. In this field,visual awareness is a topic that has been largely investigated,due to easy manipulation and measurable effects. The present arti-cle begins with the phenomena of dissociations between visual awareness and visual stimulus,visual awareness and visual attention,as well as visual awareness and vision-guided behavior,along with the corresponding experimental evidence. Furthermore,the neural mechanism of visual awareness is also discussed. It has been generally believed that visual awareness is the function of higher-order cerebral areas; however,recent discoveries have demonstrated that feedback from higher-to lower-order cortex areas is necessary for generating consciousness. The present article presents an in-depth analysis regarding this feedback process,and exploring its relation-ship with the generation and mechanisms of consciousness. Finally,theoretical controversies and discrepancies,as well as result con-flicts from various studies,have been collected,compared and discussed. Because the field of consciousness continues to be an extremely mysterious and complicated psychological phenomenon,there is a great need for further studies to explore and clarify this topic.

关键词： Visual awareness Neural mechanism Feedback process Cortical areas

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