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Dual solutions in MhD stagnation-point flow of Prandtl fluid impinging on shrinking sheet

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Applied Mathematics and Mechanics(English Edition) 2014年第7期35卷 813-820页

作者： N.S.AKBAR Z.h.KhAN R.U.hAQ S.NADEEM Department of Basic Science & humanities College of Electrical & Mechanical Engineering(CEME) National University of Sciences and Technology Islamabad 46000 Pakistan School of Mathematical Sciences Peking University Department of Mathematics University of Malakand Khyber Pakhtunktwo 18800 Pakistan Department of Mathematics Quaid-i-Azam University Islamabad 44000 Pakistan

The present article investigates the dual nature of the solution of the magneto- hydrodynamic （MhD） stagnation-point flow of a Prandtl fluid model towards a shrinking surface. The self-similar nonlinear ordinary differential equations are solved numerically by the shooting： method. It is found that the dual solutions of the flow exist for cer- tain values of tile velocity ratio parameter. The special case of the first branch solutions （the classical Newtonian fluid model） is compared with the present numerical results of stretching flow. The results are found to be in good agreement. It is also shown that the boundary layer thickness for the second solution is thicker than that for the first solution.

关键词： stagnation-point flow shrinking sheet Prandtl fluid magnetohydrody-namic (MhD) dual solution shooting method

Detrital zircon U-Pb-he double dating: A method of quantifying long- and short-term exhumation rates in collisional orogens

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Science China Earth Sciences 2014年第11期57卷 2702-2711页

作者： Christina Yan WANG Ian h.CAMPBELL Peter W.REINERS Charlotte M.ALLEN Key Laboratory of Mineralogy and Metallogeny Guangzhou Institute of Geochemistry Chinese Academy of Sciences Research School of Earth Sciences The Australian National UniversityCanberra ACT 0200 Australia Department of Geosciences University of ArizonaTucson AZ 85721 USA

A U-Pb-he double-dating method is applied to detrital zircons with core-rim structure from the Ganges River in order to de- termine average short and long-term exhumation rates for the himalayas. Long-term rates are calculated from the U/Pb ages of metamorphic rims of the grains that formed during the himalayan orogeny and their crystallization temperatures, which are calculated from the Ti-in-zircon thermometer. Short-term rates are calculated from （U-Th）/he ages of the grains with appro- priate closure temperatures. The results show that short-term rates for the himalayas, which range from 0.70 ± 0.09 to 2.67 ± 0.40 km/Myr and average 1.75 ± 0.59 （1δ） km/Myr, are higher and more varied than the long-term rates, which range from 0.84 ±0.16 to 1.85 ± 0.35 km/Myr and average 1.26 ±0.25 （let） km/Myr. The differences between the long-term and short-term rates can be attributed to continuous exhumation of the host rocks in different mechanisms in continental collision orogen. The U/Pb ages of 44.0 ± 3.7 to 18.3 ±0.5 Ma for the zircon rims indicate a protracted episode of -：25 Myr for regional metamorphism of the host rocks at deeper crust, whereas the （U-Th）/he ages of 42.2 ± 1.8 to 1.3 ± 0.2 Ma for the zircon grains represent a protracted period of -40 Myr for exposure of the host rocks to shallower crustal level. In particular, the oldest （U-Th）/he ages of the zircon grains are close to the oldest U/Pb ages for the rims, indicating that some parcels of the rocks that contain zircons were rapidly exhumed from deep to shallow levels in the stage of collisional orogeny. On the other hand, some parcels of the rocks may have been carried upwards by thrust faults in the post-collisional stage. The parcels could be carried upwards by the thrust faults that steepen as they near the surface, or by transient movement faults so that areas of rapid exhu- mation became areas of slow exhumation and visa versa on a time scale of a few Myr in order to maintain the continuous ex- huma

关键词： zircon U-Pb-he double-dating method himalayas exhumation rate collisional orogen

Differential effects on apoptosis induction in hepatocyte lines by stable expression of hepatitis B virus X protein

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World Journal of Gastroenterology 2006年第29期12卷 4673-4682页

作者： Nicola Fiedler Ellen Quant Ludger Fink Jianguang Sun Ralph Schuster Wolfram h Gerlich Stephan Schaefer Institut for Medizinische Virologie Justus-LiebigUniversitat Frankfurter Str. 107 D-35392 GieBen Germany Abteilung fǖr Innere Medizin Christian AlbrechtUniversitat Kiel Germany Zentrum fǖr Innere Medizin Justus-LiebigUniversitat GieBen Germany Abteilung Virologie Universitat Rostock Schillingallee 70 18055 Rostock Germany Institute of Agricultural Resources and Regional Planning Chinese Academy of Agricultural Sciences Beijing 100081 China

AIM： hepatitis B virus protein X （hBx） has been shown to be weakly oncogenic in vitro. The transforming activities of hBx have been linked with the inhibition of several functions of the tumor suppressor p53. We have studied whether hBx may have different effects on p53 depending on the cell type. METhODS： We used the human hepatoma cell line hepG2 and the immortalized murine hepatocyte line AML12 and analyzed stably transfected clones which expressed physiological amounts of hBx. P53 was induced by UV irradiation.RESULTS： The p53 induction by UV irradiation was unaffected by stable expression of hBx. however, the expression of the cyclin kinase inhibitor p21^waf/cip/sdi which gets activated by p53 was affected in the hBx transformed cell line AML12-hBx9, but not in hepG2. In AML-hBx9 cells, p21^waf/ciP/sdi -protein expression and p21^waf/dip/sdi transcription were deregulated. Furthermore, the process of apoptosis was affected in opposite ways in the two cell lines investigated. While stable expression of hBx enhanced apoptosis induced by UV irradiation in hepG2-cells, apoptosis was decreased in hBx transformed AML12-hBx9. P53 repressed transcription from the hBV enhancer I, when expressed from expression vectors or after induction of endogenous p53 by UV irradiation. Repression by endogenous p53 was partially reversible by stably expressed hBx in both cell lines.CONCLUSION： Stable expression of hBx leads to deregulation of apoptosis induced by UV irradiation depending on the cell line used. In an immortalized hepatocyte line hBx acted anti-apoptotic whereas expression in a carcinoma derived hepatocyte line hBx enhanced apoptosis.

关键词： Apoptosis hepatitis B virus hepatocyte lines

Soil Microbial Activities in Beech Forests Under Natural Incubation Conditions as Affected by Global Warming

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Pedosphere 2014年第6期24卷 709-721页

作者： S.LU Q.WANG S.KATAhATA M.NARAMOTO h.MIZUNAGA Graduate School of Science and Technology Shizuoka University Graduate School of Agriculture Shizuoka University

Microbial activity in soil is known to be controlled by various factors. however, the operating mechanisms have not yet been clearly identified, particularly under climate change conditions, although they are crucial for understanding carbon dynamics in terrestrial ecosystems. In this study, a natural incubation experiment was carried out using intact soil cores transferred from high altitude(1 500 m) to low(900 m) altitude to mimic climate change scenarios in a typical cold-temperate mountainous area in Japan. Soil microbial activities, indicated by substrate-induced respiration(SIR) and metabolic quotient(q CO2), together with soil physicalchemical properties(abiotic factors) and soil functional enzyme and microbial properties(biotic factors), were investigated throughout the growing season in 2013. Results of principal component analysis(PCA) indicated that soil microbial biomass carbon(MBC) andβ-glucosidase activity were the most important factors characterizing the responses of soil microbes to global warming. Although there was a statistical difference of 2.82 ℃ between the two altitudes, such variations in soil physical-chemical properties did not show any remarkable effect on soil microbial activities, suggesting that they might indirectly impact carbon dynamics through biotic factors such as soil functional enzymes. It was also found that the biotic factors mainly controlled soil microbial activities at elevated temperature,which might trigger the inner soil dynamics to respond to the changing environment. Future studies should hence take more biotic variables into account for accurately projecting the responses of soil metabolic activities to climate change.

关键词： biotic factors carbon dynamics metabolic quotient microbial biomass soil enzymes soil respiration

high Temperature Oxidation of a Work Roll Grade high-Chromium White Cast Iron

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Journal of Iron and Steel Research International 2013年第10期20卷 122-129页

作者： J h Ramírez-Ramírez R Colás N F Garza-Montes-de-Oca Faculty of Mechanical and Electrical Engineering Autonomous University of Nuevo Leon

high-chromium white cast iron is a common material for the manufacture of the work rolls used in the fin- ishing stands in hot strip mills. The high temperature oxidation behaviour of as-cast and heat-treated high-chromium white cast iron was studied by gravimetric means at 650 ℃ in atmospheres that included dry air and a mixture of dry air and water vapour. For both environmental and material conditions, the oxidation rate of the alloys was represen ted by parabolic trends and the oxidation phenomenon was more obvious when the samples were oxidised in water vapour. Water vapour also influenced the chemical composition of the oxides formed in the alloy and under this condi tion, the oxide scale formed on the alloy contained the oxides FeCr2O4 , （Fe,Cr）3O4 and （Fe,Cr）2 O3. In contrast, the alloys exposed to dry air conditions only experienced the formation of FeCr2O4 and （Fe,Cr）2O3. It was found that the presence of water vapour and the chromium content of the alloys increased the oxidation rate by a mechanism that involved chromium depletion of the oxide as a result of hydroxide formation. The differences observed in the oxi- dation behaviour of the alloy are discussed in terms of the composition of the oxidant atmosphere and the metallurgi cal condition of the specimens.

关键词： white cast iron oxidation water vapour work roll

EFFECT OF ThE DEFECT STATES DENSITY ON OPTICAL BAND GAP OF CdIn_(2)O_(4)ThIN FILM

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 403-410页

作者： h.S.San Z.G.Wu B.Li B.X.Feng KeyLaboratoryforMagnetismandMagneticMaterialofMinistryofEducation LanzhouUniversityLanzhou730000China ShanghaiInstituteofTechnicalPhysics TheChineseAcademyofSciencesShanghai200083China

Transparent conducting oxides CdIn2O4 thin films were prepared by radio-frequenc y reactive sputtering from a Cd-In alloy target in Ar+O2 atmosphere. By transmis sion spectrum and hall measurement for different samples prepared at different s ubstrate temperatures, it could be found that the carrier concentration would in crease with the decrease of substrate temperature, but absorption edge showed an abrupt variation from a blue shift to a red shift. Theoretically, the paper for mulated the effect of high-density point defects on band structures; it embodied the formation of band tailing, Burstein-Moss shift and band-gap narrowing. The density of holes will influence the magnitude of optical band gap and transmitta nce of light. Since extrapolation method does not fit degenerate semiconductor m aterials, a more accurate method of obtaining optical band gap is curve fitting. In addition, ionized impurities scattering is the main damping mechanism of the free electrons in CdIn2O4 films, the density of ionized impurities induced by a ltering substrate temperature will affect the carriers mobility.

关键词： sputtering CdIn2O4 thin film electrical property optical property

Adjusting oxygen vacancies in perovskite LaCoO_(3)by electrochemical activation to enhance the hydrogen evolution reaction activity in alkaline condition

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Journal of Energy Chemistry 2023年第1期76卷 226-232,I0006页

作者： Chengrong Wu Yan Sun Xiaojian Wen Jia-Ye Zhang Liang Qiao Jun Cheng Kelvin h.L.Zhang State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005FujianChina School of Physics University of Electronic Science and Technology of ChinaChengdu 610054SichuanChina

Developing highly-active,earth-abundant non-precious-metal catalysts for hydrogen evolution reaction(hER)in alkaline solution would be beneficial to sustainable energy *** oxides are generally regarded as low-active hER catalysts,due to their inapposite hydrogen adsorption and water ***,we report a detailed study on perovskite LaCoO_(3)epitaxial thin films as a model catalyst to significantly enhance the hER performance via an electrochemical activation *** a result,the overpotential for the activation films to achieve a current density of 0.36 m A/cm^(2)is 238 m V,reduced by more than 200 m V in comparison with that of original *** characterization revealed the activation process dramatically increases the concentration of oxygen vacancies(Vo)on the surface of LaCoO_(3).We established the relationship between the electronic structure induced by Vo and the enhanced hER *** theoretical calculations revealed that the Vo optimizes the hydrogen adsorption and dissociation of water on the surface of LaCoO_(3)thin films,thus improving the hER catalytic *** work may promote a deepened understanding of perovskite oxides for hER mechanism by Vo adjusting and a new avenue for designing highly active electrochemical catalysts in alkaline solution.

关键词： hydrogen evolution reaction Perovskite oxides Activation process Oxygen vacancies

Dental microwear of sympatric rodent species sampled across habitats in southern Africa: Implications for environmental influence

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Integrative Zoology 2016年第2期11卷 111-127页

作者： Jenny h.E.BURGMAN Jennifer LEIChLITER Nico L.AVENANT Peter S.UNGAR Environmental Dynamics Program University of ArkansasFayettevilleArkansasUSA Department of Anthropology University of Colorado BoulderBoulderColoradoUSA National Museum and University of the Free State BloemfonteinSouth Africa Department of Anthropology University of ArkansasFayettevilleArkansasUSA

Dental microwear textures have proven to be a valuable tool for reconstructing the diets of a wide assortment of fossil ***,some studies have recently questioned the efficacy of this approach,suggesting that aspects of habitat unrelated to food preference,especially environmental grit load,might have a confounding effect on microwear patterning that obscures the diet *** we evaluate this hypothesis by examining microwear textures of 3 extant sympatric rodent species that vary in diet breadth and are found in a variety of habitat types:Mastomys coucha,Micaelamys namaquensis and Rhabdomys *** sample each of these species from 3 distinct environmental settings in southern Africa that differ in rainfall and vegetative cover:Nama-Karoo shrublands(semi-desert)and Dry highveld grasslands in the Free State Province of South Africa,and Afromontane(wet)grasslands in the highlands of *** differences between habitat types are evident for some of the species,inconsistency in the pattern suggests that the microwear signal is driven by variation in foods eaten rather than grit-level per *** is clear that,at least for species and habitats sampled in the current study,environmental grit load does not swamp diet-related microwear signatures.

关键词： diet grit tooth wear

ThE STABILITY ANALYSIS OF ThE θ-METhODS FOR DELAY DIFFERENTIAL EQUMIONS

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Journal of Computational Mathematics 1996年第3期14卷 203-212页

作者： h.J.Tian J-X.Kuang(Department of Mathematics, Shanghai Normal University, Shanghai, China) 上海师范大学数学系上海

This paper deals with the stability analysis of θ-methods for the numericalsolution of delny dmerential equations (DDEs). We focus on the behavioux of suchmethods in the solution of the linear test equation y'(t) = a(t)y(t) + b(t)y(t - T),where T > o, a(t) and b(t) are functions from R to C. It is proved that the linearθ-method and the one-leg θ-method are TGP-stable if and only if θ = 1.

关键词： METhODS FOR DELAY DIFFERENTIAL EQUMIONS ThE STABILITY ANALYSIS OF ThE Math