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The steady-state solution of dendritic growth from the undercooled binary alloy melt with the far field flow

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Science china(Technological sciences) 2009年第8期52卷 2280-2287页

作者： CHEN MingWen1,2. WANG ZiDong2.& xu JianJun2.3,4 1 School of {2. sciences, {2. of Science and technology beijing, beijing 100083, china 2.School of Materials Science and Engineering, {2. of Science and technology beijing, beijing 100083, china 3 School of Mathematical sciences, Nankai {2., Tianjin 300071, china 4 Department of Mathematics and Statistics, McGill {2., Montreal H3A 2.6, Canada School of applied sciences University of Science and Technology Beijing Beijing 100083 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China School of Mathematical sciences Nankai University Tianjin 300071 China Department of Mathematics and Statistics McGill University Montreal H3A 2K6 Canada

The steady-state dendritic growth from the undercooled binary alloy melt with the far field flow is considered. By neglecting the interface energy, interface kinetics and buoyancy effects in the system, we obtaine the steady-state solution for the case of the large Schmidt number, in terms of the multiple variable expansion method. The changes of the temperature and concentration fields, the morphology of the interface, the normalization parameter and the Peclet number of the system induced by uniform external flow are derived. The results show that, compared with the system of dendritic growth from undercooled pure melt, the convective flow in the system of growth from undercooled binary alloy has stronger effects on the morphology of the interface. Nevertheless, the shape of the interface still remains nearly a paraboloid.

关键词： binary alloy melt convection dendritic growth interfaces steady-state solution multiple variable expansion method

Coupling analysis of unsteady seepage and stress fields in discrete fractures network of rock mass in dam foundation

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Science china(Technological sciences) 2011年第S1期54卷 133-139页

作者： CHAI JunRui 1,2.& xu WeiSheng 2.1 {2. of Hydraulic and Environmental Engineering,china Three Gorges {2.,Yichang 443002.china 2.{2. of Hydropower Engineering,Xi’an {2. of technology,Xi’an 710048,china 1. college of Hydraulic and Environmental Engineering China Three Gorges University Yichang 443002 China2. College of Hydropower Engineering Xi’an University of Technology Xi’an 710048 China

The drag force of water flow through single fracture and the coupling characteristics of seepage and stress in single fracture surface are analyzed,and a three dimensional model of coupled unsteady seepage and stress fields is *** model is used to the analysis of foundation rock mass of a high *** the coupling effects are considered,the changes of boundary heads have less influence on the inner head of rock mass,and the strong permeability of main fractures *** the coupling effects are not considered,the fractures distribution affects the inner head more *** the upstream water head declines,the inner head of dam foundation slightly declines and the hydraulic gradient distribution becomes smoother.A bigger upstream water level declining velocity has a stronger lag effect,meanwhile the values of stress components change more *** the upstream water level declining velocity directly affects the stability of rock mass in dam foundation and we should take into account the above factors to make sure the safety of the dam {2.ring reservoir level fluctuation period.

关键词： hydraulic engineering unsteady seepage stress coupling fractures network rock mass

Polycistronic strategy for cyanobacterial expression vector construction: Co-transcription of a human gene and a selective marker gene

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Progress in Natural Science:Materials International 2005年第9期15卷 798-803页

作者： ZhanG Yukun1, SHI Dingji2. ZHAO Feifei1, YU Meimin1 and RU Binggen1(1. college of Life Science, Peking {2., {2. 100871, china 2. college of Marine sciences & Engineering, Tianjin {2. of Science & technology, Tianjin 300450, china) college of Life Science Peking University Beijing 100871 China. college of Marine sciences & Engineering Tianjin University of Science & Technology Tianjin 300450 China

A polycistronic expression vector, pKGA-NTF1, was constructed for the cyanobacterium. Within this vector, the spectinomycin/streptomycin resistance gene (aadA) facilitated the selection of transformants when co-transcribed with favorite genes. A natural glnA gene was selected as the platform to introduce the plasmid into a neutral site of the Synechococcus sp. PCC 7002.chromosome. Function of the vector was demonstrated by the insertion of a modified human Trefoil factor 3 gene (NTF1) to upstream of the aadA gene and by the analyses of the transformed strains. Antibiotics resistance assays showed that the dicistronic expression cassette conferred high spectinomycin resistance to both the E. coli cells and the Synechococcus cells. PCR analysis and Western-blot analysis were carried out to confirm the integration and expression of the NTF1 gene, respectively. Through simple molecular manipulations, the artificial polycistronic structure described here can be conveniently used to express other favorable genes or operons in cyanobacteria, and to study the cyanobacterial gene expression as well.

关键词： cyanobacterial transformation human Trefoil factor 3 polycistronic expression Synechococcus sp. PCC 7002 vector construction.

Effect and mechanism of stresses on rock permeability at different scales

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Science china Earth sciences 2006年第7期49卷 714-723页

作者： YIN Shangxian1 & WANG Shang{2.2.1. Safety Engineering college, North china Institute of Science and {2., Yanjiao, beijing 101601, china 2. Key Laboratory of Geophysics Exploration, china university of Petroleum, beijing 100083, china 1. Safety Engineering college North China Institute of Science and Technology Yanjiao Beijing 101601 China 2. Key Laboratory of Geophysics Exploration China University of Petroleum Beijing 100083 China

The effect of geo-stress fields on macroscopic hydro-geological conditions or micro-cosmic permeability of water-bearing media should follow some laws or principles. Cases study and tests show that: (1) At macro-geologic large scale, deformed and crashed rocks which were induced by geo-stress fields changing provided space for groundwater storage and flow. Groundwater adjusts water-bearing space and dilatants fractures by flowing and press transferring. Coupling of liquid and solid can be implemented for rocks and groundwater. Although tectonic fields witness several times of change and build-up in geological time, stress fields forming regional tectonic framework are coherent with seepage fields, orientation of the maximum horizontal stress demonstrates main seepage direc-tions. (2. At macro-geologic middle scale, zones of stresses changing sharply, quite low stresses, stress or shear concentration can be used to show locations and types of main fractures, zones of geo-stresses changing equably can be acted as normal base media zones of tri-porosity media. (3) At micro-geologic small scale, tri-porosity media include fractured rocks, porous rocks and capillary rocks. Investigations indicate that porosity or permeability is functions of effective stresses, and po-rosity or permeability changing rules of porous rocks with variation of effective stresses can be de-scribed as the index model, the model of power exponent functions is suitable for those of fractured rocks, the model of the second power parabola for capillary rocks. The porosity and permeability loss in fractured rocks, which are greater than that in porous rocks, are shown by calculation of effective compressive coefficient and closing pressure in cracks. The calculations can also explain the mecha-nism why porosity changes are always larger than permeability changes. It is proved by the thick wall cylinder theory that the second power parabola relation between porosity or permeability loss and effective

关键词： geo-stress fields, seepage fields, tri-porosity media, effective stresses, permeability, porosity,scale.

Suitability evaluation for land reclamation in mining area:A case study of Gaoqiao bauxite mine

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中国有色金属学会会刊：英文版 2011年第S3期21卷 506-515页

作者： WANG Shi-dong1, 2. LIU Chang-hua2. ZhanG He-bing2.1. {2. of Resources Science and technology, {2. Normal university, {2. 100875, china 2. School of Surveying and Land Information Engineering, Henan Polytechnic university, Jiaozuo 454000, china [a] college of Resources Science and technology Beijing Normal University Beijing 100875 China [b] School of Surveying and Land Information Engineering Henan Polytechnic University Jiaozuo 454000 China

Suitability evaluation plays an important role in land reclamation because the choice of evaluation methods affects the accuracy and objectivity of the suitability evaluation results. Furthermore, it influences the decision-making related to land reclamation. An improved method, which is called limit comprehensive conditions method, was developed after different suitability evaluation methods were studied. Based on this method, the reclaimed land of the Gaoqiao bauxite mining area was evaluated. The Gaoqiao mining area was divided into seven evaluation units that were evaluated respectively by selecting evaluation factors and establishing grade standards. The results show that the proposed method is more applicable and easier to handle. Moreover, its evaluation results are more scientific compared with the traditional evaluation methods. The improved method can be beneficial to the rapid monitoring and the effective management of reclaimed land in the opencast mine area.

关键词： mining area land reclamation suitability evaluation Gaoqiao bauxite mine

Magnetron sputtering synthesis of large area well-ordered boron nanowire arrays

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Science china(Physics,Mechanics & Astronomy) 2004年第4期47卷 403-415页

作者： CAO Limin1,2. ZhanG Ze2.& WANG Wenkui1,2.1. Key Laboratory of Metastable Materials Science and {2. and college of Materials Science and Engineering, Yanshan {2., Qinhuangdao 066004, china 2. Institute of Physics, Chinese Academy of sciences, beijing 100080, china 1. Key Laboratory of Metastable Materials Science and technology and college of Materials Science and Engineering Yanshan University 066004 Qinhuangdao China 2. Institute of Physics Chinese Academy of Sciences 100080 Beijing China

One-dimensionally nanostructured materials, such as nanowires and nanotubes, are the smallest dimensional structures for efficient transport of electrons and excitons, and are therefore critical building blocks for nanoscale electronic and mechanical devices. In this paper, boron nanowires with uniform diameters from 2. to 80 nm were synthesized by radio-frequency magnetron sputtering of pure boron powder and B2.3 powder mixtures in argon atmosphere. The boron nanowires produced stand vertically on the substrate surface to form well-ordered arrays over large areas with self- organized arrangements without involvement of any template and patterned catalyst. The high-density boron nanowires are parallel to each other and well distributed, forming highly ordered and uniform arrays. A more interesting and unique feature of the boron nanowires is that most of their tips are flat rather than hemispherical in morphologies. Detailed studies on its structure and composition indicate that boron nanowires are amorphous. Boron nanowire appears as a new member in the family of one-dimensional nanostructures. Considering the unique properties of boron-rich solids and other nanostructures, it is reasonable to expect that the boron nanowires will display some exceptional and interesting properties. A vapor-cluster-solid (VCS) mechanism was proposed to explain the growth of boron nanowires based on our experimental observations.

关键词： boron nanowires, magnetron sputtering, arrays, self-assembly.

Gene characterization and phylogenetic analysis of four mitochondrial genomes in Caenogastropoda

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Acta Oceanologica Sinica 2024年第2期43卷 137-150页

作者： Jiangyong Qu Wanqi Yang Xindong Teng Li xu dachuan Z{2.g Zhikai Xing Shuang Wang Xiumei Liu Lijun Wang xumin Wang college of Life Science Yantai UniversityYantai 264005China Qingdao International Travel Healthcare Center Qingdao 266071China Qingdao Dagang Customs Qingdao 266071China

Caenogastropoda is a highly diverse group,containing~60%of all existing *** in this subclass predominantly inhabit marine environments and have a high ecological and economic *** to the increase in relevant phylogenetic studies,our understanding of between species relatedness in Caenogastropoda has ***,the biodiversity,taxonomic status,and phylogenetic relationships of this group remain *** the present study,we performed next-generation sequencing of four complete mitochondrial genomes from three families(Buccinidae,Columbellidae,and Cypraeidae)and the four mitogenomes were classical circular structures,with a length of 16177 bp in Volutharpa ampullacea,162.4 bp in Mitrella albuginosa,1692.bp in Mauritia arabica asiatica and 1542. bp in Erronea *** composition analysis indicated that whole sequences were biased toward A and *** compared them with 171 complete mitochondrial genomes of *** phylogenetic relationship of Caenogastropoda derived from Maximum Likelihood(ML)and Bayesian Inference(BI)trees constructed based on CDS sequences was consistent with the results of traditional morphological analysis,with all three families showing close *** study supported Caenogastropoda at the molecular level as a separate clade of *** to our divergence time estimations,Caenogastropoda was formed during the middle Triassic period(~2.7.2.2.7 Ma).Our novel mitochondrial genomes provide evidence for the speciation of Caenogastropoda in addition to elucidating the mitochondrial genomic evolution of this subclass.

关键词： mitochondrial genome phylogenetic analysis Caenogastropoda

The evolution and morphological stability of a spherical crystal

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Science china(Technological sciences) 2008年第3期51卷 225-243页

作者： CHEN MingWen1,2. WANG ZiDong2.& xu JianJun3,4 1 School of {2. sciences, {2. of Science and technology beijing, beijing 100083, china 2.School of Materials Science and Engineering, {2. of Science and technology beijing, beijing 100083, china 3 School of Mathematical sciences, Nankai {2., Tianjin 300071, china 4 Department of Mathematics and Statistics, McGill {2., Montreal H3A 2.6, Canada 1. School of applied sciences University of Science and Technology Beijing Beijing 100083 China 2. School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China 3. School of Mathematical sciences Nankai University Tianjin 300071 China 4. Department of Mathematics and Statistics McGill University Montreal H3A 2K6 Canada

The growth model of a spherical crystal in the undercooled melt including the surface energy, interfacial kinetics and convective flow is established. The effect of the convective flow induced by a small far field flow on the evolution and morphological stability of the interface of the spherical crystal is studied. The interface shape of the spherical crystal, which is affected by the far field flow, and the dispersion relation of the growth rate of amplitude of the perturbed interface are derived. It is shown that the convection induced by the far field flow makes the interface of the growing spherical crystal further grow in the upstream direction of the far field flow and inhibit growth in the downstream direction; the interface of the decaying spherical crystal further decays in the upstream direction and inhibits decay in the downstream direction. The theoretical result suggests that both the growth of the sphere in the upstream direction and the decay of the sphere in the downstream direction make the spherical crystal tend to evolve into an oval; the morphological stability of the interface depends on a certain radius R c such that the spherical crystal is unstable when its radius is greater t{2. R c and stable when its radius is less t{2. R c . The surface energy and interfacial kinetics have strong stabilizing effects on the growth of the spherical crystal. In the meantime interfacial kinetics is a table factor of the interface when the interface of the sphere is growing; it is an unstable factor of the interface when the interface is decaying.

关键词： solid-liquid interface spherical crystal convective flow crystal growth morphological stability

A new iguanodontid (Jin-zhousaurus yangi *** ***.) from the Yixian Formation of western Liaoning,china

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Chinese Science Bulletin 2001年第19期46卷 1669-1672页

作者： WANG Xiaolin & xu Xing1. Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of sciences, {2. 100044, {2. 2. college of Earth sciences and Resources, {2. university of Geo-sciences, {2. 100083, {2. Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences Beijing China college of Earth sciences and Resources China University of Geosciences Beijing China

A new iguanodontid, Jinzhousaurus yangi gen. et sp. nov., is erected based on the cranial and dental morphology of a specimen from the Yixian Formation of western Liaoning. Although a few primitive characteristics remain, Jinzhousaurus yangi display a number of characteristics similar to those seen in derived iguanodontids. Other interesting characteristics include the absence of antorbital fenestra and the frontal excluded from the participation in orbit, which are closer to the condition in hadrosaurids. The unusual combination of the characteristics provides important data for assessing morphological evolution toward hadrosaurs. The new discovery also represents the first reported large-sized dinosaur from Jehol fauna in western Liaoning, and increases the diversity of this famous fauna. Furthermore, the discovery of a derived iguanodontid from the Yixian Formation provides further evidence supporting a Cretaceous age of the Jehol fauna, which is consistent with an isotopic age.

关键词： Western Liaoning Lower Cretaceous Yixian Formation Jehol Biota Iguanodontid