254 research outputs found

    A wave-induced stirring mechanism in the mid-depth equatorial ocean

    Get PDF
    A wave-induced stirring and transport mechanism for the mid-depth equatorial ocean is proposed and examined using both analytic linear equatorial wave solutions and a fully nonlinear reduced-gravity model. The study of kinematic stirring using the linear solutions suggests that a superimposition of a few simple equatorial waves can lead to strong Lagrangian stirring and transport along the equator. In particular, a combination of an annual long Rossby wave and a high-frequency Yanai wave appears to be most effective in producing strong stirring in the interior equatorial region. Further investigations of stirring properties using an inverted, fully nonlinear reduced gravity shallow-water model support the results of the kinematic stirring study. By evaluating the finite-time estimates of Lyapunov exponents, we identified two regions where chaotic stirring is most active. One is the western boundary region where short Rossby waves likely play a dominant role in producing the strong chaotic stirring. The other is the equatorial waveguide where a low-frequency Rossby wave prescribes the pattern of the stirring geometry, and a high-frequency Yanai wave plays a role of stirring the fluid. The proposed stirring mechanism provides a plausible explanation of the observed chlorofluorocarbon distribution found in the mid-depth equatorial Atlantic Ocean

    Terephthalic acid–4,4′-bipyridine (2/1)

    Get PDF
    In the title compound, 2C8H6O4·C10H8N2, the 4,4′-bipyridine mol­ecule is located on an inversion centre. In the crystal structure, strong inter­molecular O—H⋯N hydrogen bonds between the terephthalic acid and 4,4′-bipyridine mol­ecules lead to the formation of chains with graph-set motif C 2 2(8) along the diagonal of the bc plane

    catena-Poly[[bis­(p-toluene­sulfonato-κO)palladium(II)]bis­(μ-1,3-di-4-pyridylpropane-κ2 N:N′)]

    Get PDF
    In the title compound, [Pd(C7H7O3S)2(C13H14N2)2]n, the metal ion, located on a twofold rotation axis, exhibits a slightly distorted octa­hedral coordination environment, with bond angles that deviate by at most 2.2° from an ideal geometry, completed by two O atoms from two deprotonated p-toluene­sulfonic acid ligands and four N atoms from four 1,3-di-4-pyridylpropane ligands. One of the sulfonate O atoms is disordered over two positions [ratio 0.70 (5):0.30 (5)]

    Bis(ethano­lato-κO)(5,10,15,20-tetra­phenyl­calix[4]pyrrole)manganese(III) hexa­fluoro­phosphate

    Get PDF
    The title compound, [Mn(C2H5O)2(C44H28N4)]PF6, was synthesized from manganese(III) 2,4-penta­nedionate and 5,10,15,20-tetra­phenyl­calix[4]pyrrole by a hydro­thermal reaction. The MnIII atom is located on an inversion centre and the asymmetric unit comprises one half-formula unit. The MnIII ion is hexa­coordinated by four N atoms from one 5,10,15,20-tetra­phenyl­calix[4]pyrrole ligand and two O atoms from two deprotonated ethanol mol­ecules. The equatorially located atoms (the Mn and four N atoms) are planar. The dihedral angles between the planes of the phenyl rings and the equatorial plane are 53.3 (2) and 81.8 (2)°. One hexa­fluoro­phosphate anion balances the charge

    Spatio-temporal variations of health costs caused by chemical fertilizer utilization in China from 1990 to 2012

    Get PDF
    The health impacts caused by chemical fertilizer utilization have challenged long-term sustainable development in many countries, particularly developing countries. Based on the emergy analysis method, we estimated the temporal and spatial variations of the health costs, through atmospheric, water, and soil pathways, of chemical fertilizer utilization in China during the period from 1990 to 2012. The results showed an obvious increasing trend of health costs from 1.8 billion Yuan in 1990 to 23.0 billion Yuan in 2012, while the ratio of health costs to agriculture output value declined slowly and became stable in recent years. Regional differences were remarkable and were significantly correlated to the levels of economic development (r = 0.843 and p < 0.001) and crop-sown area in the region (r = 0.588 and p < 0.001). Economically developed regions, especially the eastern coastal provinces, had much higher costs than the western regions. Meanwhile, fertilizer consumption shifted from the eastern to the northwest region, which was the same as the health costs. This study provides a reference to estimate the health costs of fertilizer utilization, and the results highlight the importance of sustainable development in China
    corecore