Ocean University of China

About: Ocean University of China is a education organization based out in Qingdao, China. It is known for research contribution in the topics: Population & Sea surface temperature. The organization has 27604 authors who have published 27886 publications receiving 440181 citations. The organization is also known as: Zhōngguó Hǎiyáng Dàxué & OUC.

Spatiotemporal dynamics of the archaeal community in coastal sediments: assembly process and co-occurrence relationship

Abstract: Studies of marine benthic archaeal communities are updating our view of their taxonomic composition and metabolic versatility. However, large knowledge gaps remain with regard to community assembly processes and inter taxa associations. Here, using 16S rRNA gene amplicon sequencing and qPCR, we investigated the spatiotemporal dynamics, assembly processes, and co-occurrence relationships of the archaeal community in 58 surface sediment samples collected in both summer and winter from across ~1500 km of the eastern Chinese marginal seas. Clear patterns in spatiotemporal dynamics in the archaeal community structure were observed, with a more pronounced spatial rather than seasonal variation. Accompanying the geographic variation was a significant distance-decay pattern with varying contributions from different archaeal clades, determined by their relative abundance. In both seasons, dispersal limitation was the most important process, explaining ~40% of the community variation, followed by homogeneous selection and ecological drift, that made an approximately equal contribution (~30%). This meant that stochasticity rather than determinism had a greater impact on the archaeal community assembly. Furthermore, we observed seasonality in archaeal co-occurrence patterns: closer inter-taxa connections in winter than in summer, and unmatched geographic patterns between community composition and co-occurrence relationship. These results demonstrate that the benthic archaeal community was assembled under a seasonal-consistent mechanism but the co-occurrence relationships changed over the seasons, indicating complex archaeal dynamic patterns in coastal sediments of the eastern Chinese marginal seas.

A New Blocking Index and Its Application: Blocking Action in the Northern Hemisphere

Abstract: In this paper, a new two-dimensional blocking index is proposed by defining a difference between the daily 500-hPa geopotenial heights at the reference latitude and its north side. The reference latitude is determined by a composite latitude-dependent 500-hPa geopotenial height of blocking events in different seasons and sectors. The new index can take account of the duration, intensity, propagation, and spatial structure of a blocking event. Using this index, the characteristics (frequency, duration, intensity, and preferred occurrence region) of the blocking action in the North Hemisphere (NH) are investigated using a 42-yr sample of blocking events from the NCEP–NCAR reanalyses. It is found that blocking events in the NH are more frequent in the Atlantic–Europe sector than in the Pacific sector in winter and spring and autumn, but more persistent in the Atlantic–Europe sector than in the Pacific sector for all seasons. Blocking events in the Pacific sector tend to have larger amplitudes than t...

Significantly improved dielectric performances of sandwich-structured polymer composites induced by alternating positive-k and negative-k layers

Abstract: High-k polymer composites are promising candidates for energy-storage capacitors and many other electronic devices. However, balancing the permittivity, loss and breakdown strength remains a challenge for us. Herein, theoretical calculations and experimental studies were simultaneously carried out to develop an original design of sandwich-structured composites consisting of alternating negative-k and positive-k layers toward high performance dielectric applications. It is experimentally proved that the trilayered composites are capable of balancing the two contrasting parameters of permittivity and loss. The introduction of negative-k layers into trilayered composites leads to a higher dielectric constant (e′ ≈ 90@10 kHz) and low retained loss (tan δ ≈ 0.025@10 kHz) compared with those of the pristine PVDF (e′ ≈ 10@10 kHz, tan δ ≈ 0.020@10 kHz). Moreover, the trilayered composites possess an obviously improved energy-storage capacity which is nearly 3 times higher than those of traditional trilayered composites without negative-k layers. Although the permittivity boost effect is still far below the theoretically predicted results and the mechanisms need to be further clarified, these results undoubtedly validated the feasibility of our design, and multilayer high-k composites with fascinating dielectric performances are expected to emerge in the near future via tailoring the properties of single layers and stacking sequences.