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Selenium metabolism in animals and humans

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Journal of Environmental Sciences 1996年第3期8卷 328-340页

作者： P.D.Whanger(Department of Agricultural Chemistry, Oregon University, Oregon 97331-7301, usa) Department of Agricultural Chemistry Oregon University Oregon 97331-7301 United States

The main purpose of this paper is to point out the differences in the metabolism of Se between animals and humans. This is not to imply that the work with animals is not applicable to human because the use of animals in Se research has greatly assisted in understanding Se metabolism in human subjects. It is fair to conclude that until results are confirmed in humans it is risky to draw conclusions on Se metabolism in human based solely on animal data. Although animals have provided some extremely useful information on metabolism of Se,there is convincing evidence to indicate that some features of Se metabolism are unique to human. A few examples were given to support this contention.

关键词： Se metabolism animals human.

FOUR STEP SCHEME FOR GENERAL MARKOVIAN FORWARD-BACKWARD SDES

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Journal of Systems Science & Complexity 2010年第3期23卷 546-571页

作者： Jin MA Jiongmin YONG Yanhong ZHAO Department of Mathematics University of Southern California Los Angeles CA 90089 USA Department of Mathematics University of Central Florida Orlando FL 32816 USA Department of Mathematics Purdue University West Lafayette IN 47907 USA

This paper studies a class of forward-backward stochastic differential equations (FBSDE)in a general Markovian *** forward SDE represents a large class of strong Markov semimartingales,and the backward generator requires only mild regularity *** authors showthat the Four Step Scheme introduced by Ma,et al.(1994) is still effective in this ***,the authors show that the adapted solution of the FBSDE exists and is unique over any prescribedtime duration;and the backward components can be determined explicitly by the forward componentvia the classical solution to a system of parabolic integro-partial differential *** importantconsequence the authors would like to draw from this fact is that,contrary to the general belief,in aMarkovian set-up the martingale representation theorem is no longer the reason for the well-posednessof the FBSDE,but rather a consequence of the existence of the solution of the decoupling integralpartialdifferential ***,the authors briefly discuss the possibility of reducing the regularityrequirements of the coefficients by using a scheme proposed by *** (2002) to the current case.

关键词： Forward-backward stochastic differential equations Four Step Scheme parabolic integropartial differential equation strong Markov semi-martingales.

Dependence of Hurricane Intensity and Structures on Vertical Resolution and Time-Step Size

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Advances in Atmospheric Sciences 2003年第5期20卷 711-725页

作者： Da-Lin ZHANG and Xiaoxue WANGDepartment of Meteorology, University of Maryland, College Park, Maryland, 20742 usa Department of Meteorology University of Maryland 20742 College Park Maryland USA

In view of the growing interests in the explicit modeling of clouds and precipitation, the effects of varying vertical resolution and time-step sizes on the 72-h explicit simulation of Hurricane Andrew (1992) are studied using the Pennsylvania State University/National Center for Atmospheric Research (PSU/NCAR) mesoscale model (i.e., MM5) with the finest grid size of 6 km. It is shown that changing vertical resolution and time-step size has significant effects on hurricane intensity and inner-core cloud/precipitation, but little impact on the hurricane track. In general, increasing vertical resolution tends to produce a deeper storm with lower central pressure and stronger three-dimensional winds, and more precipitation. Similar effects, but to a less extent, occur when the time-step size is reduced. It is found that increasing the low-level vertical resolution is more efficient in intensifying a hurricane, whereas changing the upper-level vertical resolution has little impact on the hurricane intensity. Moreover, the use of a thicker surface layer tends to produce higher maximum surface winds. It is concluded that the use of higher vertical resolution, a thin surface layer, and smaller time-step sizes, along with higher horizontal resolution, is desirable to model more realistically the intensity and inner-core structures and evolution of tropical storms as well as the other convectively driven weather systems.

关键词： hurricane intensity vertical resolution numerical weather prediction

Agrobacterium-mediated transformation and assessment of factors influ-encing transgene expression in loblolly pine （Pinus taeda L.）

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Cell Research 2001年第3期11卷 237-243页

作者： TANG WEI North Carolina State University, 2900 Ligon Sf., Raleigh, NC 27607, usa 1North Carolina State University 2900 Ligon St. Raleigh NC 27607 USA.

This investigation reports a protocol for transfer and expression of foreign chimeric genes in loblolly pine (Pinus taeda L.). Transformation was achieved by co-cultivation of mature zygotic embryos with Agrobacterium tumefaciens strain LBA4404 which harbored a binary vector (pBI121) including genes for β-glucuronidase (GUS) and neomycin phosphotransferase (NPTII). Factors influencing transgene expression including seed sources of loblolly pine, concentration of bacteria, and the wounding procedures of target explants were investigated. The expression of foreign gene was confirmed by the ability of mature zygotic embryos to produce calli in the presence of kanamycin, by histochemical assays of GUS activity, by PCR analysis, and by Southern blot. The successful expression of the GUS gene in different families of loblolly pine suggests that this transformation system is probably useful for the production of the genetically modified conifers.

关键词： Pinus taeda L. Agrobacterum tumefaciens gene transfer gene expression.

HIGH TEMPERATURE COMPOSITES

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Acta Metallurgica Sinica(English Letters) 1995年第Z1期8卷 467-476页

作者： M. V. Nathal (NASA Lewis Research Center Cleveland OH. usa) NASA Lewis Research Center Cleveland United States

The purpose of this paper is to review the current state of development of new composite materials for advanced aircraft engines. The advantages and disadvantages of ***-base, and MoSi_2-base composites as replacements for today's Ni-base superalloys are discussed from the standpoint of key technical issues. current status, and future directions. Results describing progress in both improved understanding of the mechanisms of deformation and fracture, and improved material performance will be covered.

关键词： composites. Ti alloys Ti-aluminides NiAl MoSi_2-base jet engines

Structural Applications of NiAl

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Journal of Materials Science & Technology 1994年第3期10卷 157-169页

作者： R.Darolia(GE Aircraft Engines, 1 Neumann Way, Cincinnati, OH 45215, usa) GE Aircraft Engines Cincinnati United States

Alloys based on NiAl offer significant payoffs as structural materials in gas turbine applications due to a unique range of physical and mechanical properties These properties include high melting temperature. low density. high thermal conductivity. and excellent environmental resistance Very significant improvements in the strength and ductility of NiAl single crystals have been achieved through alloying. Tensile strength and stress rupture properties which compete with current Ni-base Superalloys have been achieved through precipitation of an ordered L21 Heusler phase in NiAl single crystals Room temperature tensile ductility as high as 6% has been produced in NiAl single crystals containing less than 0.5% (atomic) of Fe. Ga or Mo. However. a single alloy with both room temperature ductility and sufficient high temperature strength has not yet been developed. While activity to develop on alloy with both high temperature strength and room temperature ductility continues. the Current approach also emphasizes design and test methodologies which can accept a material with limited ductility and damage tolerance More work is required on measuring and understanding strain rate sensitivity and impact behaviour While several significant challenges still remain. excellent progress has been made in many areas, and the prognosis for using NiAl alloys as high temperature structural materials is promising

关键词： Structural Applications of NiAl TR III RS Res OH NATO MPa EDM IV

INTERIOR ERROR ESTIMATES FOR NONCONFORMINGFINITE ELEMENT METHODS OF THE STOKES EQUATIONS

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Journal of Computational Mathematics 1999年第5期17卷 475-494页

作者： Xiao-bo Liu(Department of Mathematics and Computer Science Clarkson University Box 5815, Potsdam,NY 13699-5815, usa) Clarkson Univ Dept Math & Comp Sci Potsdam NY 13699 USA

Interior error estimates are derived for nonconforming stable mixed finite element discretizations of the stationary Stokes equations. As an application, interiorconvergences of difference quotients of the finite element solution are obtained forthe derivatives of the exact solution when the mesh satisfies some translation invariant condition. For the linear element, it is proved that the average of thegradients of the finite element solution at the midpoint of two interior adjacenttriangles approximates the gradient of the exact solution quadratically.

关键词： Interior error estimates Nonconforming element Stokes equations.

Posterior gut development in Drosophila:a model system for identifying genes controlling epithelial morphogenesis

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Cell Research 1998年第4期8卷 273-284页

作者： LENGYEL JUDITH A XUE JUN LIU (Department of Molecular, Cell and Developmental Biology University of California at Los Angeles, Los Angeles, CA usa, 90095-1606 usa) Department of Molecular Cell and Developmental Biology University of California at Los Angeles Los Angeles CA USA 90095-1606 USA

The posterior gut of the Drosophila embryo, consisting of hindgut and Malpighian tubules, provides a simple,well-defined system where it is possible to use a genetic approach to define components essential for epithelial *** review here the advantages of Drosophila as a model genetic organism, the morphogenesis of the epithelial structures of the posterior gut, and what is known about the genetic requirements to form these *** overview, primordia are patterned by expression of hierarchies of transcription factors; this leads to localized expression of cell signaling molecules, and finally, to the least understood step: modulation of cell adhesion and cell shape. We describe approaches to identify additional genes that are required for morphogenesis of these simple epithelia, particularly those that might play a structural role by affecting cell adhesion and cell shape.

关键词： Organogenesis cell rearrangement convergent extension hindgut Malpighian tubule

Total synthesis of(+)-lentiginosine via a key Au catalysis

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Science China Chemistry 2010年第1期53卷 113-118页

作者： CUI Li & ZHANG LiMing Department of Chemistry & Biochemistry,University of California,Santa Barbara,CA 93106,usa 1. Department of Chemistry & Biochemistry University of California Santa Barbara CA 93106 USA

Total syntheses of(+)-lentiginosine and its 8a-epimer using a gold-catalyzed oxidative cyclization as the key step were *** gold chemistry,reported previously in a 4+2 synthesis of piperidin-4-ones,tolerates functiona... 详细信息

关键词： gold total synthesis cyclization oxidation alkaloid