10 research outputs found

    Study on the disyllabic third-tone sandhi in Shaanxi Middle Area Mandarin

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    This study investigates the disyllabic third-tone sandhi in Shaanxi Middle Area Mandarin. It is a common phenomenon that T3 changes to another tone before T3 in two-syllable words in Mandarin dialects. Shaanxi is the primary region where T3 changes to T1 before T3. In this study, 10 geographical points of Middle Area Mandarin in Shaanxi are explored. Additionally, combining it with closely related types such as Middle Area Mandarin in other places, Jin and Hakka, three types of the disyllabic third-tone sandhi in Shaanxi Middle Area Mandarin are analyzed. We propose that these types reflect different historical strata. The tone change rule, which states that a T3 changes to a T1 before T3, was established during the Tang Dynasty and spread throughout the surrounding regions. And now, this rule is disappearing

    One-dimensional ballistic transport with FLAPW Wannier functions

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    We present an implementation of the ballistic Landauer-B\"uttiker transport scheme in one-dimensional systems based on density functional theory (DFT) calculations within the full-potential linearized augmented plane-wave (FLAPW) method. In order to calculate the conductance within the Green's function method we map the electronic structure from the extended states of the FLAPW calculation to Wannier functions which constitute a minimal localized basis set. Our approach benefits from the high accuracy of the underlying FLAPW calculations allowing us to address the complex interplay of structure, magnetism, and spin-orbit coupling and is ideally suited to study spin-dependent electronic transport in one-dimensional magnetic nanostructures. To illustrate our approach we study ballistic electron transport in non-magnetic Pt monowires with a single stretched bond including spin-orbit coupling, and in ferromagnetic Co monowires with different collinear magnetic alignment of the electrodes with the purpose of analysing the magnetoresistance when going from tunneling to the contact regime. We further investigate spin-orbit scattering due to an impurity atom. We consider two configurations: a Co atom in a Pt monowire and vice versa. In both cases, the spin-orbit induced band mixing leads to a change of the conductance upon switching the magnetization direction from along the chain axis to perpendicular to it. The main contribution stems from ballistic spin-scattering for the magnetic Co impurity in the non-magnetic Pt monowire and for the Pt scatterer in the magnetic Co monowire from the band formed from states with dxyd_{xy} and dx2−y2d_{x^2-y^2} orbital symmetry. We quantify this effect by calculating the ballistic anisotropic magnetoresistance which displays values up to as much as 7% for ballistic spin-scattering and gigantic values of around 100% for the Pt impurity in the Co wire

    Overpressure reservoirs of the Huangliu Formation of the Dongfang area, Yinggehai Basin, South China Sea

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    The relationship between reservoir property and such factors as sedimentary microfacies, clastic component, grain size, and special diagenetic environment of high temperature and overpressure were comprehensively analyzed to study reservoir characteristics and influencing factors in the first member of upper-Miocene Huangliu Formation of the DF13-1 structure in the Dongfang area, Central Diapir Zone of the Yinggehai Basin. The dominant reservoirs in the first member of the Huangliu Formation in the Dongfang area are composed of very fine to fine lithic quartz sandstones that are deposited in submarine fans sourced from the Kuntom Uplift. The reservoirs are characterized by large thickness, broad distribution and good qualities. High-temperature thermal fluids activities and overpressure are two major diagenetic factors contributing to the good properties in the reservoirs. Thermal fluids activities of high tempreture accelerated the organic matter thermal evolution and clay mineral transformation, and in this process organic acids and CO2 were generated which dissolved the reservoirs and thus resulted in a secondary pore zone. Overpressure broadened oil generation window, increased corrosion time and strength, making secondary pores developed in deeper formations. Moreover, the overpressure was beneficial to preserve pores. The reservoir economic basement depths of siltstone, very fine sandstone and fine sandstone are about 3 100 m, 3 900 m and 5 000 m respectively. The fine sandstone and very fine sandstone in the first member of the Huangliu Formation could form high-quality gas reservoirs in present depth of 2 600–3 500 m. Key words: submarine fan, thermal fluid, overpressure, economic basement, reservoir property, Yinggehai Basi

    Geological load and health risk of heavy metals uptake by tea from soil: What are the significant influencing factors?

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    As one of the most popular beverages around world, factors influencing transfer of heavy metals from soil to tea leaves is crucial to investigate and assess health risk through tea drinking. Parent material (PM), soil and tea samples from Anhui province, typical tea producing area in China were collected in this study. To find out distribution characteristics of heavy metals in tea and soil, and influencing factors for transfer process, variables of plantation factors, soil properties and geological background were taken into account. The results showed that weathering pedogenic process could be the main release source of heavy metals in soil under the acid environment for tea growth. More than 75% of soil Cd, Hg, Pb and Zn exceeded background. However heavy metals in tea samples were below the limits of China, WHO and EU standards. Soil organic matter and redox process influenced the distribution and transfer of As, Pb, Cd and Hg in soil and tea. While geochemical behaviours of Cr, Cu, Ni and Zn were mainly related to soil pH and iron oxides in tea garden. The method of classification and regression trees (CART) showed clones of tea type, bedrock type, soil texture, soil organic and fertilizer application were identified as the main factors influencing transfer factors of heavy metals from soil to tea. The specific types of tea grown in the soil with sandy clay and bedrock of granite/granodiorite and shale should be given more monitoring. The non-carcinogenic hazard quotients (HQ) and cancer risk (Risk) through tea drinking were primarily caused by Pb and Cd respectively. To reduce the potential health risk from tea, application of organic and/or compound fertilizer were thought to be the effective management strategy for tea plantation.</p
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