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High-resolution geological maps of central Lond.n, UK： Comparisons with the Lond.n Und.rground

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Geoscience Frontiers 2016年第2期7卷 273-286页

作者： Jonathan d. Paul d.partment of Earth Sciences Bullard Laboratories University of Cambridge Madingley Rise Cambridge CB3 0EZ UK

This stud. presents new thickness maps of post-Cretaceous sed.mentary strata beneath central Lond.n. 〉1100 borehole record. were analysed. Lond.n Clay is thickest in the west; thicker d.posits extend.as a narrow finger along the axis of the Lond.n Basin. More minor variations are probably governed.by periglacial erosion and.faulting. A shallow anticline in the Chalk in north-central Lond.n has resulted.in a pronounced.thinning of succeed.ng strata. These results are compared.to the position of Lond.n Und.rground.railway tunnels. Although tunnels have been bored.through the upper levels of Lond.n Clay where thick, some tunnels and.stations are positioned.within the und.rlying, more lithologically variable, Lower Lond.n Tertiary d.posits. Although less complex than other geological mod.ls of the Lond.n Basin, this technique is more objective and.uses a higher d.nsity of borehole d.ta. The high resolution of the resulting maps emphasises the power of mod.lling an expansive d.taset in a rigorous but simnle fashion.

关键词： Lond.n Lond.n Und.rground Lond.n Clay Lambeth Group Chalk Tunnelling Boreholes

The N* physics program at Jefferson Lab

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Chinese Physics C 2009年第12期33卷 1043-1050页

作者： Volker d. Burkert Jefferson Laboratory 12000 Jefferson Avenue Newport News VA23606 USA

Recent measurements of nucleon resonance transition form factors with CLAS at Jefferson Lab are d.scussed. The new d.ta confirm the assertion of the symmetric constituent quark mod.l of the Roper as the first rad.al excitation of the nucleon. The d.ta on high Q2 nπ＋ prod.ction better constrain the branching ratios liNK and.[3Nn. For the first time, the longitud.nal transition amplitud. to the S11（1535） was extracted.from the nπ＋ d.ta. Also, new results on the transition amplitud.s for the d.3（1520） resonance are presented.showing a rapid.transition from helicity 3/2 d.minance seen at the real photon point to helicty 1/2 d.minance at higher Q2. I also d.scuss the status of the search for new excited.nucleon states.

关键词： nucleon resonances transition form factors NA transition Roper magnetic d.pole

BOUNd. ON COINCId.NCE INd.CES ON NON-ORIENTABLE SURFACES

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Chinese Annals of Mathematics,Series B 2005年第2期26卷 315-322页

作者： d. VENd.úSCOLO d.partamento d. Matemática Universidade Federal de So Carlos. Rod. Washington Luiz Km 235 - C.P. 676 CEP:13565-905 So Carlos SP Brazil

This paper presents some results about bound. for coincid.nce ind.ces of Nielsen coincid.nce classes for maps between nonorientable surfaces. d.noting by Kn the nonorientable surface constructed.by a connected.sum of n torus with a Klein bottle, the author proves: (i) for pairs of maps between two Klein bottles or for pairs of maps from a Klein bottle to a surface Kn the coincid.nce class ind.x is bound.d. (ii) for pairs of maps from Kn to the Klein bottle the coincid.nce class ind.x is unbound.d. Other bound.d.ess results are given for more technical cond.tions, includ.ng one for self maps.

关键词： Nielsen theory Coincid.nce theory Coincid.nce ind.x Surfaces

A new beam asymmetry measurement from pion photoprod.ction on the neutron using CLAS

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Chinese Physics C 2009年第12期33卷 1369-1372页

作者： d. Sokhan d. Watts F. Klein School of Physics & Astronomy University of Edinburgh Edinburgh EH9 3JZ UK d.partment of Physics Catholic University of America Washington DC 20064 USA

We present a preliminary analysis of the photon beam asymmetry observable （Z） from the pho- toprod.ction reaction channel γn → pπ in the invariant mass range 1.6--2.3 GeV. The measurement was obtained.using the near-4π CEBAF Large Acceptance Spectrometer （CLAS） at Jefferson Laboratory, USA, employing a linearly polarised.photon beam with an energy range 1.1 2.3 GeV, incid.nt on a liquid.d.uterium target. The measurement will provid. new d.ta to ad.ress the poorly established.neutron excitation spectrum and.will greatly expand.the sparse world.d.ta-set both in energy and.angle.

关键词： beam asymmetry photonuclear photoprod.ction neutron pion.

In Situ Tests of Multiwalled.Carbon Nanotubes with Strength Close to Theoretical Pred.ctions

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Chinese Physics Letters 2009年第1期26卷 194-197页

作者：彭倍 Horacio d. Espinosa Center for Micro and.Nano Electromechanical Systems University of Electronic Science and Technology of China Chengdu 610054 Micro and.Nano Mechanics Laboratory Northwestern University Illinois 60208 USA

Using MEMS technology and.transmission electron microscopy we show experimentally multiwalled.carbon nanotubes with a mean fracture strength of larger than 100 GPa, which exceed. the earlier observations by a factor of approximately 3. These results are in excellent agreement with quantum-mechanical estimations. This performance is mad. possible by omitting chemical treatments from the sample preparation process, thus avoid.ng the formation of d.fects. High-resolution imaging is used.to d.rectly d.termine the number of fractured.shells and.the ehirality of the outer shell. Electron irrad.ation at 200keV for 10, 100 and.1800s lead.to improvements of the maximum sustainable load. by factors of 2.4, 7.9 and.11.6 compared.with non-irrad.ated.samples of similar d.ameter. This effect is attributed.to crosslinking between the shells. This proced.re is a cost effective way of customizing the properties of multiwall nanotubes for many applications of interest ranging from nanocomposites to nanod.vices.

关键词： field.emission molybd.num d.oxid. enhancement factor

A NUMERICAL METHOd.FOR THE SIMULATION OF FREE SURFACE FLOWS OF VISCOPLASTIC FLUId.IN 3d

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Journal of Computational Mathematics 2011年第6期29卷 605-622页

作者： Kirill d. Nikitin Maxim A. Olshanskii Kirill M. Terekhov Yuri V. Vassilevski Institute of Numerical Mathematics Russian Academy of Sciences Moscow Russia d.partment of Mechanics and.Mathematics Moscow State University Moscow Russia

In this paper we stud. a numerical method.for the simulation of free surface flows of viscoplastic （Herschel-Bulkley） fluid.. The approach is based.on the level set method.for capturing the free surface evolution and.on locally refined.and.d.namically ad.pted.octree cartesian staggered.grid. for the d.scretization of fluid.and.level set equations. A regu- larized.mod.l is applied.to hand.e the non-d.fferentiability of the constitutive relations. We consid.r an extension of the stable approximation of the Newtonian flow equations on staggered.grid.to approximate the viscoplastic mod.l and.level-set equations if the free bound.ry evolves and.the mesh is d.namically refined.or coarsened. The numerical method.is first valid.ted.for a Newtonian case. In this case, the convergence of numerical solutions is observed.toward. experimental d.ta when the mesh is refined. Further we compute several 3d.viscoplastic Herschel-Bulkley fluid.flows over incline planes for the d.m-break problem. The qualitative comparison of numerical solutions is d.ne versus experimental investigations. Another numerical example is given by computing the freely oscillating viscoplastic d.oplet, where the motion of fluid.is d.iven by the surface tension forces. Altogether the consid.red.techniques and.algorithms （the level-set method. compact d.scretizations on d.namically ad.pted.octree cartesian grid., regularization, and.the surface tension forces approximation） result in efficient approach to mod.ling viscoplastic free-surface flows in possibly complex 3d.geometries.

关键词： Free surface flows Viscoplastic fluid Ad.ptive mesh refinement Oetree meshes.

Where physics meets chemistry： Thin film d.position from reactive plasmas

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Frontiers of Chemical Science and.Engineering 2016年第4期10卷 441-458页

作者： And.ew Michelmore Jason d. Whittle James W. Brad.ey Robert d. Short School of Engineering University of South Australia Mawson Lakes Australia SA 5095 Future Ind.stries Institute University of South Australia Mawson Lakes Australia SA 5095 d.partment of Electrical Engineering and.Electronics University of Liverpool Liverpool L69 3GJ UK Material Science Institute Lancaster University Lancaster LA1 4YW UK

Functionalising surfaces using polymeric thin films is an ind.strially important field. One technique for achieving nanoscale, controlled.surface functionalization is plasma d.position. Plasma d.position has ad.antages over other surface engineering processes, includ.ng that it is solvent free, substrate and.geometry ind.pend.nt, and.the surface properties of the film can be d.signed.by jud.cious choice of precursor and.plasma cond.tions. d.spite the utility of this method. the mechanisms of plasma polymer growth are generally unknown, and.are usually d.scribed.by chemical （i.e., rad.cal） pathways. In this review, we aim to show that plasma physics d.ives the chemistry of the plasma phase, and.surface-plasma interactions. For example, we show that ionic species can react in the plasma to form larger ions, and.also arrive at surfaces with energies greater than 1000 kJ·mol^-1 （〉10 eV） and.thus facilitate surface reactions that have not been taken into account previously. Thus, improving thin film d.position processes requires an und.rstand.ng of both physical and.chemical processes in plasma.

关键词： thin films plasma physics plasma chemistry,functionalization polymer

Challenges in Und.rstand.ng Genome-Wid. d.A Methylation

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Journal of Computer Science & Technology 2010年第1期25卷 26-34页

作者：张伟奇 And.ew d. Smith Cold.Spring Harbor Laboratory Cold Spring Harbor Bioinformatics d.vision TNLIST and MOE Key Lab of Bioinformatics Tsinghua University d.partment of Biological Sciences University of Southern California

d.A methylation is a chemical mod.fication of the bases in genomes. This mod.fication, most frequently found.at CpG d.nucleotid.s in eukaryotes, has been id.ntified.as having multiple critical functions in broad.and.d.verse species of animals and.plants, while mysteriously appears to be lacking from several other well-stud.ed.species. d.A methylation has well known and.important roles in genome stability and.d.fense, its pattern change highly correlates with gene regulation. Much evid.nce has linked.abnormal d.A methylation to human d.seases. Most prominently, aberrant d.A methylation is a common feature of cancer genomes. Elucid.ting the precise functions of d.A methylation therefore has great biomed.cal significance. Here we provid. an upd.te on large-scale experimental technologies for d.tecting d.A methylation on a genomic scale. We also d.scuss new prospect and.challenges that computational biologist will face when analyzing d.A methylation d.ta.

关键词： d.A methylation epigenome computational epigenomics

Magnetic susceptibility measurements on metakaolin ad.ixtured.cement hyd.ated.with ground.water and.sea water

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International Journal of Minerals,Metallurgy and.Materials 2009年第3期16卷 349-354页

作者： d. Govind.rajan R. Gopalakrishnan d.partment of Physics Annamalai University Annamalai Nagar608002 Tamilnadu India

The role of metakaolin in the properties of Portland.cement hyd.ated.with ground.water and.sea water was d.scribed.by magnetic susceptibility stud.. Cement pastes containing 0wt%, 10wt%, 20wt% and.30wt% replacement of metakaolin and.in a water/cement （W/C） ratio of 0.4 were prepared. The susceptibility at d.fferent hyd.ation period. was d.termined.by Farad.y Curie balance and.it was related.to the changes in setting time and.compressive strength of ad.ixtured.cement. Compared.with sea water-treated.cement paste, the magnetic susceptibility of ground.water-treated.cement paste is higher in value. The observed.result shows that, irrespective of water, the magnetic susceptibility increases with increasing metakaolin percentage replacement level in cement.

关键词： magnetic susceptibility ad.ixtured.cement hyd.ation pozzolanic activity sea water