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Nitrogen is an important factor that influences the yield and quality of wheat grain. However, little is known about its effect on the different positions of the grain in spikelets. Compared with the control group, nitrogen application increased the weight, starch content, and protein content of grains in each position considerably. In particular, the protein content in high grain positions of Yangmai 13 (YM 13) under nitrogen treatment are similar to those positions in Yannong 19 (YN 19) under normal levels. Nitrogen application substantially increased the volume proportion of small starch granules and the average degree of polymerization (DP) but reduced the apparent amylose content (AAC), and the breakdown values (BV) of the first grain (G1) and the second grain (G2) in YN19. Nitrogen application considerably increased AAC, the volume proportion of small starch granules, and the ordered structure of starch surface of G1 and AAC, BV, and DP of G2 in YM13. These results demonstrated that a medium nitrogen level is conducive to increase the agronomic traits in high‐position grains and a better pasting properties of starch in low‐position grains. [ABSTRACT FROM AUTHOR]

The development of highly efficient metal‐free carbon electrocatalysts for the oxygen reduction reaction (ORR) is one very promising strategy for the exploitation and commercialization of renewable and clean energy, but this still remains a significant challenge. Herein, we demonstrate a facile approach to prepare three‐dimensional (3D) N‐doped carbon with a sp3/sp2 carbon interface derived from ionic liquids via a simple pyrolysis process. The tunable hybrid sp3 and sp2 carbon composition and pore structures stem from the transformation of ionic liquids to polymerized organics and introduction of a Co metal salt. Through tuning both composition and pores, the 3D N‐doped nanocarbon with a high sp3/sp2 carbon ratio on the surface exhibits a superior electrocatalytic performance for the ORR compared to that of the commercial Pt/C in Zn–air batteries. Density functional theory calculations suggest that the improved ORR performance can be ascribed to the existence of N dopants at the sp3/sp2 carbon interface, which can lower the theoretical overpotential of the ORR. [ABSTRACT FROM AUTHOR]