Proton belt variations traced back to Fengyun-1C satellite observations

We used historical data to trace trapped protons observed by the Fengyun-1C(FY-1C)satellite at low Earth orbits(~800 km)and chose data at 5–10 MeV,10–40 MeV,40–100 MeV,and^100–300 MeV from 25 March to 18 April 2000 to analyze the proton variations.Only one isolated strong storm was associated with a solar proton event during this period,and there was no influence from previous proton variations.Complex dynamic phenomena of proton trapping and loss were affected by this disturbance differently depending on the energy and L location.The flux of 5–10 MeV protons increased and created new trapping with a maximum at L^2.0,and the peak flux was significantly higher than that at the center of the South Atlantic Anomaly.However,at higher L,the flux showed obvious loss,with retreat of the outer boundary from L^2.7 to L^2.5.The increase in the 10–40 MeV proton flux was similar to that of the 5–10 MeV flux;however,the peak flux intensity was lower than that at the center of the South Atlantic Anomaly.The loss of the 10–40 MeV proton flux was closer to the Earth side,and the outer boundary was reduced from L^2.3 to L^2.25.For the higher energy protons of 40–100 MeV and 100–300 MeV,no new trapping was found.Loss of the 40–100 MeV protons was observed,and the outer boundary shifted from L^2.0 to L^1.9.Loss was not obvious for the 100–400 MeV protons,which were distributed within L<1.8.New proton trapping was more likely to be created at lower energy in the region of solar proton injection by the strong magnetic storm,whereas loss occurred in a wide energy range and reduced the outer boundary on the Earth side.Similar dynamic changes were observed by the NOAA-15 satellite in the same period,but the FY-1C satellite observed more complex changes in lower energy protons.These results revealed that the dynamic behavior of protons with different L-shells was due to differences in the pitch angle.Possible mechanisms related to new trapping and loss are also discussed.These mechanisms are very important for understanding the behavior of the proton belt in the coming solar cycle.

Comparison of environmental responding strategies between Ulva prolifera and Sargassum horneri:an in-situ study during the co-occurrence of green tides and golden tides in the Yellow Sea,China in 2017

Large-scale green tides in the Yellow Sea occurred for 13 consecutive years since 2007.The unusual co-occurrence of green tides and golden tides occurred in the Yellow Sea in 2017.The causative species are Ulva prolifera and/or Sargassum horneri.Previous studies on physiological response characteristics of U.prolifera and S.horneri are done in the laboratory mainly,and there is no in-situ comparative study in this regard.In this study,the in-situ physiological response characteristics of both species were measured.The results indicated that cyclic electron flow and antioxidant system play more important roles in protecting U.prolifera,while non-photochemical quenching is more important for adapting to the environment in S.horneri.U.prolifera has a stronger ability to utilize nutrients to rapidly increase its biomass under a suitable condition compared to S.horneri.

Surface effects on the indentation of a soft layer on a rigid substrate with an elliptical cylinder indenter

Surface effects often play a significant role in the mechanical properties of soft materials such as hydrogels and biological tissues.In this paper,we investigate the plane-strain indentation of a soft elastic layer bonded to a rigid substrate.The surface effects on the indentation behavior of the elastic layer-substrate system are theoretically analyzed.Indentation tests using indenters with different elliptical shapes are compared.Analytical expressions are derived for the indentation force-displacement relation using the Kerr model with the effect of surface tension.The theoretical solution is verified by finite element simulations.The dependence of surface effects on the ratio of the indenter’s major and minor elliptical axes is also examined.This work helps understand the size effects on the indentation behaviors of soft materials and guides the design of corresponding measurement tests.