A dynamic irrigation scheme that considers groundwater processes and dynamic vegetation was constructed and incorporated into Noah land surface model with multiparameterization options coupled with the weather research and forecasting model. Multiple experiments (with and without irrigation) were designed to simulate the impacts of irrigation over the North China Plain (NCP) on regional climate. The simulated irrigation rate of the NCP was close to observations, and its interannual variations were clearly associated with dry or wet years. The groundwater table affected by irrigation varied in the NCP irrigated areas during simulation period but declined overall. The irrigation-induced increases in green vegetation fraction led to increases in transpiration, indicating that the influences of irrigation on latent heat flux should contain the changes of transpiration besides changes of soil evaporation. The modified surface energy budget caused by irrigation affected surface air temperature (SAT), and the spring and summer SAT in the areas with larger irrigation rate decreased significantly by 0.8-1.6 and 1.2-2.6°C, respectively. The experiment that considered irrigation showed obvious improvement in simulating several key variables (gross primary productivity, green vegetation fraction, sensible heat flux, and summer SAT). In the NCP, irrigation increased water vapor and caused cooling in boundary layer, which had opposing influences on precipitation, resulting in heterogeneous changes in summer precipitation. The changes of precipitation in nonirrigated areas were related to the influences of irrigation on wind fields. The contribution of direct effects of irrigation to blended influences of irrigation and dynamic vegetation on spring (summer) SAT was 70.9% (63.8%).
Developing high-performance DNA-based biocatalysts for desired stereoselective syntheses remains a formidable challenge. Here, we report promising DNA-based catalysts comprised of G-quadruplex (G4) and Fe porphyrin for asymmetric olefin cyclopropanation. After the G4-based catalysts are optimized by several rounds of site mutation, their catalytic enantioselectivities achieve +81% and −86% enantiomeric excess (ee trans ) at a turnover number (TON) as high as 500. The Fe porphyrin, binding upon the 5′,3′-end G-quartet, constitutes the active center for olefin cyclopropanation via an iron porphyrin carbene intermediate. The findings provide an opportunity for generating high-value chiral cyclopropane blocks via G4 biocatalysts and shed light on the potential of DNA as protein enzymes for catalysis.
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