Modeling impact of culture facilities on hydrodynamics and solute transport in marine aquaculture waters of North Yellow Sea

An increasing number of marine aquaculture facilities have been placed in shallow bays and open sea,which might significantly affect hydrodynamic and solute transport processes in marine aquaculture waters.In this study,a coupled hydrodynamic and solute transport model was developed with high-resolution schemes in marine aquaculture waters based on depth-averaged shallow water equations.A new expression of drag force was incorporated into the momentum equations to express the resistance of suspended culture cages.The coupled model was used to simulate the effect of suspended structures on tidal currents and the movement of a contaminant cloud in the marine aquaculture of the North Yellow Sea,China.The simulation results showed a low-velocity area appearing inside the aquaculture cage area,with a maximum reduction rate of velocity close to 45%under high-density culture.The results also showed that tidal currents were sensitive to the density of suspended cages,the length of cages,and the drag coefficients of cages.The transport processes of pollutants inside aquaculture facilities were inhibited away from the vicinity of the culture cage area because of the diminished tidal currents.Therefore,the suspended cages significantly affected the transport processes of pollutants in the coastal aquaculture waters.Furthermore,the reduced horizontal velocity significantly decreased the food supply for the aquaculture areas from the surrounding sea.

Comparison of Body Mass Index with Body Fat Percentage in the Evaluation of Obesity in Chinese

Objective To evaluate the present Chinese body mass index （BMI） criteria with body fat percentage （BF%） in determining obesity in Chinese population. Methods A total of 4 907 subjects （age： 20-90 yrs） were enrolled in the baselirie survey of a longitudinal epidemiological study, and 2 638 of them were reevaluated in 5.5 years later. The Chinese BMI and WHO BF% were used to define obesity, respectively. Results The diagnostic agreement between the Chinese BMI and WHO BF% definitions for obesity was poor for both men （kappa： 0.210, 95% CI： 0.179-0.241） and women （kappa： 0.327, 95% CI： 0.296-0.358）. However, BMI had a good correlation with BF% both in men （r： 0.785, P〈0.01） and women （r： 0.864, P〈0.01）. The age and sex-adjusted relative risks （RR） for incidence of type 2 diabetes （T2DM） were significantly higher in subjects with intermediate BF% （BF%：20.1%-25% for men, 30.1%-35% for women） （RR： 2.35, 95% CI： 1.23-4.48） and high BF%（BF%〉25% for men and 〉35% for women）（RR： 2.89, 95% CI： 1.43-5.81）, or in subjects with high BMI （BMI≥ 28 kg/m2） （RR： 2.46, 95% CI： 1.31-4.63） when compared to those with low BF% （BF%≤20% for men ands〈30% for women） or low BMI （BMI〈24 kg/m^2） respectively. No difference in risk could be found in those with intermediate BMI （BMI： 24-27.9 kg/m^2） （RR： 1.44, 95% CI： 0.86-2.40）, as compared to those with low BMI （BMI〈24 kg/m^2）, whose BF% ranged widely from 7.8 to 50.3%. Conclusion BMI was correlated with BF%. Both BMI and BF% were associated with high risk for T2DM. However, BMI had its limitations in the interpretation of subjects with BMI between 24 and 27.9 kg/m^2.

Shape Anisotropy and Resonance Mode Guided Reliable Interconnect Design for In-plane Magnetic Logic

Dipole coupled nanomagnets controlled by the static Zeeman field can form various magnetic logic interconnects.However, the corner wire interconnect is often unreliable and error-prone at room temperature. In this study, we address this problem by making it into a reliable type with trapezoid-shaped nanomagnets, the shape anisotropy of which helps to offer the robustness. The building method of the proposed corner wire interconnect is discussed,and both its static and dynamic magnetization properties are investigated. Static micromagnetic simulation demonstrates that it can work correctly and reliably. Dynamic response results are reached by imposing an ac microwave field on the proposed corner wire. It is found that strong ferromagnetic resonance absorption appears at a low frequency. With the help of a very small ac field with the peak resonance frequency, the required static Zeeman field to switch the corner wire is significantly decreased by ~21 m T. This novel interconnect would pave the way for the realization of reliable and low power nanomagnetic logic circuits.

Surface Modification for WSe2 Based Complementary Electronics

High-performance WSe2 complementary transistors are demonstrated on an individual flake by ozone exposure,which relies on the charge transfer mechanism.This technology is readily feasible for modulating the conductivity type in WSe2,and the p–n junction presents a high on-off ratio of 104.Based on robust p-type transistors and matched output current of n-type WSe2 transistors,the complementary inverter achieves a high voltage gain of 19.9.Therefore,this strategy may provide an avenue for development of high-performance complementary electronics.

A numerical study of hydrodynamic characteristics and hydrological processes in the coastal wetlands during extreme events

Providing accurate predictions of extreme water levels through numerical simulation has become essential for disaster prevention and damage mitigation in coastal wetland areas.This study applies the FVCOM model to simulate storm surges caused by several typhoons in the Bohai Sea and the North Huanghai Sea.The vegetation drag force caused by salt marsh plants is inserted into the FVCOM model for model improvement with vegetation effect by integrating RS and GIS technologies.A parametric typhoon model is coupled with background wind fields derived to acquire the spatio-temporal variations of wind and pressure fields in the computational domain.The simulation results reproduce the extreme storm surges induced by typhoon events very well.The modeling results are compared by validating with literature results to examine the effect of vegetation on tidal waves in tidal mud flats.Moreover,the coupled model is also applied to explore storm surge attenuation and land intrusion during Typhoon Winnie in the wetlands of the Liao River Estuary.The simulation results indicate that salt marsh plants can reduce the flow current with little impact on tide flooding/ebbing in vegetated regions.Furthermore,the results show that typhoon presence increases the inundation depth and extendes the flood time in the tidal wetlands of the study region.The FVCOM model incorporating the method with vegetation drag force can provide new insights to understand the comprehensive impact of tidal wetland plants on hydrodynamic characteristics in the Bohai Sea and other waters,hence presents a more accurate quantification of the hydrological process of storm surge in the tidal wetlands.

Numerical investigation of the effects of aquatic plants on wind-induced currents in Taihu Lake in China

Shallow lakes are an important part of the earth's water circulation system, and many factors may impact the evolution of the lake water circulation, including the wind, the topography, the human activities, and the aquatic plants. This paper proposes a depth-averaged 2-D hydrodynamic model to investigate the interaction of the wind-induced current and the aquatic plant in the lake. The model is based on the generalized shallow water equations solved by an explicit finite volume method with unstructured triangular grids. The drag force of the vegetation is considered into the momentum equations as the source term. Remote sensing techniques are applied to evaluate the aquatic vegetation in the Taihu Lake, China, based on Landsat TM satellite images. The study model is then used to simulate the characteristics of the wind-induced currents in the Taihu Lake, without and with the vegetation effects. The simulation results are in good agreement with the field measurements, demonstrating that the aquatic plants significantly affect the magnitude of the velocity and the flow circulation induced by the wind in the Taihu Lake. In addition, a sensitivity analysis reveals that the plant parameters (the density and the drag force coefficient) are significant factors influencing the velocity and the structure of the currents in the Taihu Lake.

Chemical approach to generating long-term self-renewing pMN progenitors from human embryonic stem cells

Spinal cord impairment involving motor neuron degeneration and demyelination can cause lifelong disabilities,but effective clinical interventions for restoring neurological functions have yet to be developed.In early spinal cord development,neural progenitors of the motor neuron(pMN)domain,defined by the expression of oligodendrocyte transcription factor 2(OLIG2),in the ventral spinal cord first generate motor neurons and then switch the fate to produce myelin-forming oligodendrocytes.Given their differentiation potential,pMN progenitors could be a valuable cell source for cell therapy in relevant neurological conditions such as spinal cord injury.However,fast generation and expansion of pMN progenitors in vitro while conserving their differentiation potential has so far been technically challenging.In this study,based on chemical screening,we have developed a new recipe for efficient induction of pMN progenitors from human embryonic stem cells.More importantly,these OLIG2+pMN progenitors can be stably maintained for multiple passages without losing their ability to produce spinal motor neurons and oligodendrocytes rapidly.Our results suggest that these self-renewing pMN progenitors could potentially be useful as a renewable source of cell transplants for spinal cord injury and demyelinating disorders.