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.

Two-dimensional biomass-derived carbon nanosheets and MnO/carbon electrodes for high-performance Li-ion capacitors

Abstract: Li-ion capacitors have been considered as next-generation advanced energy storage systems to meet the requirements of both high energy and high power due to the combination of rapid and long-term charge storage of supercapacitors and the high energy storage capacity of lithium ion batteries. Herein, we demonstrate the design of 2D nanostructured electrodes from low-cost biomass-kapok fiber for Li-ion capacitors: 2D carbon nanosheets with a high surface area and hierarchical porosity for the positive electrode, and 2D MnO/C nanocomposites with a large surface area and nanosized particles for the negative electrode. With the benefit of the structure of the Li-ion capacitor, the hybrid device can be operated at a high operating voltage of 4 V, exhibiting a high energy density of 100 W h kg−1 at 83 W kg−1, a high power density of 20 kW kg−1 at 30 W h kg−1 based on the active materials, and a capacity retention ratio of 70% after 5000 cycles. These results clearly demonstrate that biomass-derived electrodes are potential candidates for low-cost, fast and efficient energy storage systems in the future.

Seasonal variation of suspended-sediment transport through the southern Bohai Strait

Abstract: Based on field observations made in winter 2006 and summer 2007 and on multiscene MODerate resolution Imaging Spectrometer (MODIS) imagery, the seasonal variation of suspended-sediment transport in the southern Bohai Strait and its possible mechanisms are examined. The field observations in two different seasons allow an exponential empirical model to be used to retrieve suspended-sediment concentration (SSC) from MODIS imagery. Both the field-survey data and the MODIS-derived SSC show that the sediment transport in the southern Bohai Strait has a significant seasonal variation due to the seasonally varying thermohaline structure of the water column and the hydrodynamics resulting from the seasonally alternating monsoons. The SSC in winter is approximately 3–10 times higher than in summer. Considering the seasonal variation of water flux (WF) and SSC, the annual sediment flux (SSF) through the southern Bohai Strait is estimated to be approximately 40.0 Mt yr−1, about 4–8 times previous estimates, which did not take into account seasonal variation. Although the Huanghe (Yellow River) discharges a large amount of sediment in the summer, the SSF through the southern Bohai Strait in the winter (∼32.0 Mt) is about 4 times greater than it is in the summer. The strong seasonal variability of SSF through the southern Bohai Strait indicates that strong resuspension along the coast of the Huanghe delta in winter and enhanced longshore transport by coastal currents due to winter monsoon activity might be the major mechanisms of cross-strait transport of sediment in winter.