Plasma equilibrium calculation in J-TEXT tokamak

Plasma equilibrium has been calculated using an analytical method. The plasma profiles of the current density, safety factor, pressure and magnetic surface function are obtained. The analytical solution of the Grad–Shafranov（GS） equation is obtained by the variable separation method and compared with the computed results of the equilibrium fitting code EFIT.

Response of soil CO_2 efflux to precipitation manipulation in a semiarid grassland

Soil CO_2efflux（SCE） is an important component of ecosystem CO_2 exchange and is largely temperature and moisture dependent, providing feedback between C cycling and the climate system. We used a precipitation manipulation experiment to examine the effects of precipitation treatment on SCE and its dependences on soil temperature and moisture in a semiarid grassland. Precipitation manipulation included ambient precipitation, decreased precipitation（- 43%）, or increased precipitation（＋ 17%）. The SCE was measured from July2013 to December 2014, and CO_2 emission during the experimental period was assessed.The response curves of SCE to soil temperature and moisture were analyzed to determine whether the dependence of SCE on soil temperature or moisture varied with precipitation manipulation. The SCE significantly varied seasonally but was not affected by precipitation treatments regardless of season. Increasing precipitation resulted in an upward shift of SCE–temperature response curves and rightward shift of SCE–moisture response curves,while decreasing precipitation resulted in opposite shifts of such response curves. These shifts in the SCE response curves suggested that increasing precipitation strengthened the dependence of SCE on temperature or moisture, and decreasing precipitation weakened such dependences. Such shifts affected the predictions in soil CO_2 emissions for different precipitation treatments. When considering such shifts, decreasing or increasing precipitation resulted in 43 or 75% less change, respectively, in CO_2 emission compared with changes in emissions predicted without considering such shifts. Furthermore, the effects of shifts in SCE response curves on CO_2 emission prediction were greater during the growing than the non-growing season.

Xylan/chitosan composites prepared by an ionic liquid system with unique antioxidant properties

Antioxidant function and solubility in water are highly desirable in many applications of chitosan.In this paper,a xylan/chitosan composite was prepared in an ionic liquid system using glutaraldehyde as a crosslinking agent.The antioxidant activity,reducing capacity and metal ion chelating ability of the resulting composite were determined.The chemical structure and thermal stability were analyzed by FT-IR,XRD and TGA.The results showed that chitosan was successfully cross-linked with xylan by glutaraldehyde in the ionic liquid system.Compared to pure chitosan,the ABTS·+scavenging activity of the xylan/chitosan composite increased from 10.56%to 97.59%.After cross-linking with xylan by glutaraldehyde,the reducing power of xylan/chitosan composite increased from 0.054 to 2.109.The capacity of chelating metal ion of the composite also increased from 42.35%to 86.71%compared to that of pure chitosan.An underlying mechanism was proposed to account for the improvement of the chemical properties of the chitosan in the composite.