To obtain critical information on distribution and abundance of Indo-Pacific humpback dolphins (Sousa chinensis) residing in the Pearl River Estuary (PRE), systematic line-transect surveys and photo-identification studies were conducted in the eastern and western sections of the estuary in 2005–2006 and 2007–2008, respectively. Dolphins in the eastern section occurred throughout Lingding Bay, whereas their distribution in the western section extended from the mouth of Modaomen to the channel between Shangchuan and Xiachuan islands. Variations in dolphin distribution during the wet and dry seasons were evident and probably associated with movements of their prey species. Photo-identification of individuals confirmed exchange of at least some individuals between the western and eastern sections of PRE, and thus dolphins from both areas almost certainly comprise a single population. Using line-transect analysis, the total population size of the PRE humpback dolphins was estimated to be 2555 during the wet season and 2517 during the dry season. However, these should be considered preliminary as the coefficients of variation in some survey areas were high. Further studies should focus on refining these estimates and working towards understanding the western boundary of the PRE population.
The fluorinated bis(phenoxyimine)Ti complexes (FI catalyst) are immobilized onto the polyhedral oligomeric silsesquioxane (POSS)-modified silica for the preparation of ultrahigh molecular weight polyethylene (UHMWPE) with a weakly entangled state. The POSSs can assemble to spherical nanoaggregates with an average size of 60 nm, which can serve as isolators to separate the active species and growing chains. The weakly entangled UHMWPE is prepared with an exceptional activity owing to this isolation. The evolution of entanglements for polymer chains is studied based on the fragmentation of catalytic particles. It is evidenced by the results of polymerization and characterization that 30 min of polymerization is the critical time for the entire fragmentation of catalytic particles. Importantly, this fragmentation leads to a rupture of the reacted environment which is established by the POSS nanoaggregates. Further polymerization will synthesize the UHMWPE with more entangled density.
Cu12Sb4S13 has aroused great interest
because of its earth-abundant constituents and intrinsic low thermal
conductivity. However, the applications of Cu12Sb4S13 are hindered by its poor thermoelectric performance.
Herein, it is shown that Gd substitution not only causes a significant
increase in both electrical conductivity σ and thermopower S but also leads to dramatic drop in lattice thermal conductivity κ
L. Consequently, large ZT reaches 0.94 at 749 K for Cu11.7Gd0.3Sb4S13, which is ∼41% higher than the ZT value of undoped sample. Rietveld refinements of XRD
results show that accompanying inhibition of impurity phase Cu3SbS4, the number of Cu vacancies increases substantially
with substituted content x (x ≤
0.3), which leads to reduced κ
L owing
to intensive phonon scattering by the point defects and increased
σ arising from the charged defects (V
Cu
’
). Crucially, synchrotron radiation photoelectron spectroscopy
reveals substantial increment of electronic density of states at Fermi
level upon Gd substitution, which is proven, by our first-principle
calculations, to originate from contribution of Gd 4f orbit, resulting
in enhancement of S. Our study provides us with a
new path to enhance thermoelectric performance of Cu12Sb4S13.
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