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Strategies towards robust interpretations of in situ zircon Lu-Hf isotope analyses

Geoscience Frontiers 2020年第3期11卷 843-853页

作者： c.j.Spencer c.L.Kirkland N.M.W.Roberts N.j.Evans j.Liebmann School of Earth and Planetary Sciences The Institute for Geoscience Research(TIGeR)Curtin UniversityPerthAustralia department of Geological Sciences and Geological Engineering Queen’s UniversityKingstonCanada centre for Exploration Targeting-curtin Node The Institute for Geoscience ResearchSchool of Earth and Planetary SciencesCurtin UniversityPerthAustrali Geochronology and Tracers Facility British Geological SurveyNottinghamUK john de Laeter centre GeoHistory Facility School of Earth and Planetary SciencesCurtin UniversityPerthAustralia

The combination of U-Pb and Lu-Hf compositions measured in zircon crystals is a remarkably powerful isotopic couplet that provides measures on both the timing of mineral growth and the radiogenic enrichment of the source from which the zircon *** U-Pb age documents the timing of zircon crystallization/recrystallization and Hf isotopes inform on the degree to which the host melt was derived from a radiogenic reservoir(*** mantle) versus an unradiogenic reservoir(*** continental crust),or some mixture of these *** ease of generating large quantities of zircon U-Pb and Lu-Hf data has been in large part facilitated by instrument ***,the dramatic increase in time constrained zircon Lu-Hf analyses in the Earth science community has brought to the fore the importance of careful data collection and reduction workflows,onto which robust geological interpretations may be *** this work,we discuss the fundamentals of Lu-Hf isotopes in zircon,which then allows us to provide a robust,accessible,methodology for the assessment of data ***,we discuss some novel techniques for:data visualization—that facilitates better transparency of data interpretation;integration of geographic information—that may reveal spatial trends where temporal trends were only apparent before;and some novel statistical evaluation tools—that may provide more rigorous interand intra-sample comparisons.

关键词： Zircon Geochronology Isotope geochemistry Lu-Hf isotopes Geostatistics Data visualization

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Plasma density measurement and downstream etching of silicon and silicon oxide in Ar/NF3 mixture remote plasma source

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Plasma Science and Technology 2019年第6期21卷 52-57页

作者： H j YEOM D H cHOI Y S LEE j H KIM D j SEONG S j YOU H c LEE Korea Research Institute of Standards and Science(KRISS) Daejeon 34113 Republic of Korea department of Physics Chungnam National University Daejeon 34134 Republic of Korea

In this study,plasma density measurements were performed near the plume region of the remote plasma source (RPS) in Ar/NF3 gas mixtures using a microwave cutoff *** measured plasma density is in the range of 1010-1011 cm-3 in the discharge conditions with RPS powers of 2-4 kW and gas pressures of 0.87-4 *** plasma density decreased with increasing gas pressures and RPS powers under various Ar/NF3 mixing *** decrease in the plasma density measured at the fixed measurement position (plume region) can be understood by the reduction of the electron energy relaxation length with increases in the gas pressures and mixing ratio of NF3/(Ar/NF3).We also performed downstream etching of silicon and silicon oxide films in this *** etch rate of the silicon films significantly increases while the silicon oxide is slightly etched with the gas pressures and *** was also found that the etch rate strongly depends on the wafer position on the processing chamber electrode,and that the etch selectivity reached 96-131 in the discharge conditions of RF powers (3730-4180 W) and gas pressures (3.6-4 Torr).

关键词： remote plasma source electron density cutoff probe downstream etch

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Site Selective Excitation and Energy Transfer in LiKGdF_5 crystal co-doped with Er^(3+) and Tb (3+)

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journal of Rare Earths 2004年第1期22卷 22-26页

作者：尹民 Khaidukov N M Krupa j c Structure Research Laboratory Kurnakov Institute of General and Inorganic chemistry Institut de Physique Nucléaire

crystals of LiKGdF 5∶Er 3+, Tb 3+ grown by the hydrothermal synthesis technique with concentrations of 2% and 0.4% were analysed. By using site selective excitation measured at low temperature, luminescence and excitation spectra from Er 3+ and Tb 3+ ions embedded in LiKGdF 5 were clearly separated. The lifetimes of the emitting levels 4S 3/2 of Er 3+ and 5D 4 of Tb 3+ were also determined. Following the site selective spectroscopy study, the dominant energy transfer process from Tb 3+ to Er 3+ in the crystal was then investigated via transient experiments.

关键词： optics condensed matter physics energy transfer luminescence LiKGdF 5∶Er3+, Tb3+ rare earths

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Influence of texture and microstructure on mechanical properties of high-strength wrought magnesium alloy AZ80

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中国有色金属学会会刊：英文版 2006年第A3期16卷 1754-1757页

作者：张平 j.LINdeMANN c.LEYENS National Engineering Research center of Light Alloy Net Forming Shanghai Jiao Tong UniversityShanghai 200030China chair of Physical Metallurgy and Materials Technology Technical University of Brandenburg at CottbusGermany

Monotonic (tensile and compressive) and high cycle fatigue properties of the forged magnesium alloy AZ80 were investigated by using specimens with load axis parallel to longitude (L) or transverse (T) direction. A pronounced directional anisotropy in monotonic tests was observed in AZ80, i.e. the yield stress in T-direction is significantly lower than that in L direction. However, the directional anisotropy is absent in fatigue, fatigue strengths in both L- and T-directions are essentially equal. The absence of directional anisotropy in fatigue is possibly associated with the microstructure of AZ80. A homogeneous single phase structure probably alleviates the directional anisotropy of fatigue properties of the wrought magnesium alloy.

关键词：镁合金机械性能强度微观结构

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Ground control monitoring of retreat room–and–pillar mine in central Appalachia

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International journal of Mining Science and Technology 2017年第1期27卷 65-69页

作者： Erik c.Westman Ryan j.Molka William j.conrad Mining and Minerals Engineering department Virginia TechBlacksburgVA 24061USA

In order to study pillar and overburden response to retreat mining, a ground control program was conducted at a central Appalachian Mine. The program consisted of several monitoring methods including a seismic monitoring system, borehole pressure cells in the pillars, and time-lapse photogrammetry of the pillar ribs. Two parallel geophone arrays were installed, one on each side of the panel with the sensors mounted 3 m into the roof. A total of fourteen geophones recorded more than 5000 events during the panel retreat. A MIDAS datalogger was used to record pressure from borehole pressure cells(BPcs)located in two adjacent pillars that were not mined during retreat. A series of photographs were taken of the pillars that had the BPcs as the face approached so that deformation of the entire rib could be monitored using photogrammetry. Results showed that pillar stability and cave development were as expected. The BPcs showed an increase in loading when the face was 115 m inby and a clear onset of the forward abutment at 30 m. The photogrammetry results displayed pillar deformation corresponding to the increased loading. The microseismic monitoring results showed the overburden caving inby the face, again as expected. The significance of these results lies in two points,(1) we can quantify the safe manner in which this mine is conducting retreating operations, and(2) we can use volumetric technologies(photogrammetry and microseismic) to monitor entire volumes of the mine in addition to the traditional point-location geotechnical measurements(BPcs).

关键词： Retreat mining Stress measurement Microseismic monitoring Pillar stability

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International NeuroAIDS: prospects of HIV-1 associated neurological com-plications

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cell Research 2005年第Z1期15卷 962-969页

作者： j Roberto TRUjILLO Gilberto jARAMILLO-RANGEL Marta ORTEGA-MARTINEZ Augusto c PENALVA de OLIVEIRA jose E VIDAL joseph BRYANT Robert c GALLO Institute of Human Virology University of Maryland Biotechnology Institute 725 W Lombard Street Baltimore MD 21201 USA Institute of Infectious Diseases Emilio Ribas Sao Paulo 01246 Brazil Clinical Research Unit in Human Retrovirology University of CampinasSao Paulo 01246 Brazil. Institute of Infectious Diseases Emilio Ribas Sao Paulo 01246 Brazil

Neurological complications associated with HIV-1/AIDS are being recognized with a high frequency that parallels the increased number of AIDS cases. The early infiltration by HIV-1 into the nervous system can cause primary and/or secondary neurological complications. The most common neurocognitive disorder is AIDS dementia complex (ADc). In developing countries of Asia the three most opportunistic infections are tuberculosis (TB), cryptococcosis, and Pneumocystis carinii pneumonia. Therefore, it is expected that secondary neurological complications due to TB and cryptococcosis will be the most common cause of morbility and mortality in HIV-1/AIDS cases in china. Research of NeuroAIDS in china is necessary to understand the impact and the biology of HIV-1 in the nervous system. Future studies would include, the molecular epidemiology and the description of opportunistic infections associated to HIV-1; the neuropathological description of primary and secondary HIV-1 complications in different groups; the HIV-1 neurot- ropism and immune response studies for china’s unique HIV-1 strains and recombinant forms derived from the nervous system, including experimental models such as the use of transgenic rats; and the study of potential resistant virus, primarily when the anti-retroviral therapy (ART) has not full access in the brain.

关键词： NeuroAIDS HIV-1 neurotropism AIDS dementia complex.

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Quantitative Study on Nonmetallic Inclusion Particles in Steels by Automatic Image Analysis With Extreme Values Method

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journal of Iron and Steel Research International 2009年第4期16卷 18-21,32页

作者： cássio Barbosa josé Brant de campos jneo Lopes do Nascimento Iêda Maria Vieira caminha National Institute of Technology

The presence of nonmetallic inclusion particles which appear during steelmaking process is harmful to the properties of steels, which is mainly as a function of some aspects such as size, volume fraction, shape, and distribution of these particles. The automatic image analysis technique is one of the most important tools for the quantitative determination of these parameters. The classical Student approach and the Extreme Values Method （EVM） were used for the inclusion size and shape determination and the evaluation of distance between the inclusion particles. The results thus obtained indicated that there were significant differences in the characteristics of the inclusion particles in the analyzed products. Both methods achieved results with some differences, indicating that EVM could be used as a faster and more reliable statistical methodology.

关键词： image analysis steel microstructure nonmetallic inclusion

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SHARED VALUE IN A FINITE-DIMENSIONAL BANAcH MANIFOLD

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Acta Mathematica Scientia 2010年第5期30卷 1687-1695页

作者： j.M.Soriano departamento de Ana'lisis Matem'atico Facultad de Matema'ticasUniversidad de Sevilla

Sufficient conditions are given to assert that two c1-mappings share only one value in a connected compact Banach manifold modelled over Rn. The proof of the result, which is based upon continuation methods, is constr... 详细信息

关键词： regular value continuation methods atlas chart Banach manifold compactness

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Electro-osmotic flow of a second-grade fluid in a porous microchannel subject to an Ac electric field

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journal of Hydrodynamics 2013年第2期25卷 309-316页

作者： MISRA j. c. cHANDRA S. department of Mathematics Institute of Technical Education and Research Siksha O Anusandhan University department of Physics Sabang S. K. Mahavidyalaya Vidyasagar University

Studies on electro-osmotic flows of various types of fluids in microchannel are of great importance owing to their multifold applications in the transport of liquids, particularly when the ionized liquid flows with respect to a charged surface in the presence of an external electric field. In the case of viscoelastic fluids, the volumetric flow rate differs significantly from that of Newtonian fluids, even when the flow takes place under the same pressure gradient and the same electric field. With this end in view, this paper is devoted to a study concerning the flow pattern of an electro-osmotic flow in a porous microchannel, which is under the action of an alternating electric field. The influence of various rheological and electro-osmotic parameters, e.g., the Reynolds number, debye-Huckel parameter, shape factor and fluid viscoelasticity on the kinematics of the fluid, has been investigated for a secondgrade viscoelastic fluid. The problem is first treated by using analytical methods, but the quantitative estimates are obtained numerically with the help of the software MATHEMATIcA. The results presented here are applicable to the cases where the channel height is much greater than the thickness of the electrical double layer comprising the Stern and diffuse layers. The study reveals that a larger value of the debye-Huckel parameter creates sharper profile near the wall and also that the velocity of electro-osmotic flow increases as the permeability of the porous microchannel is enhanced. The study further shows that the electro-osmotic flow dominates at lower values of Reynolds number. The results presented here will be quite useful to validate the observations of experimental investigations on the characteristics of electro-osmotic flows and also the results of complex numerical models that are necessary to deal with more realistic situations, where electro-osmotic flows come into the picture, as in blood flow in the micro-circulatory system subject to an elect

关键词： electrical double layer debye length second-grade fluid Ionic energy

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A DIREcT SEARcH FRAME-BASED cONjUGATE GRADIENTS METHOD

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journal of computational Mathematics 2004年第4期22卷 489-500页

作者： I.D.coope c.j.Price departmentofMathematicsandStatistics UniversityofCanterburyPrivateBag4800ChristchurchNewZealand

A derivative-free frame-based conjugate gradients algorithm is presented. convergence is shown for c^1 functions, and this is verified in numerical trials. The algorithm is tested on a variety of low dimensional problems, some of which are ill-conditioned, and is also tested on problems of high dimension. Numerical results show that the algorithm is effective on both classes of problems. The results are compared with those from a discrete quasiNewton method, showing that the conjugate gradients algorithm is competitive. The algorithm exhibits the conjugate gradients speed-up on problems for which the Hessian at the solution has repeated or clustered eigenvalues. The algorithm is easily parallelizable.

关键词： conjugate gradients derivative-free Frame-based methods Numerical results

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