Aroma is an important quality parameter for breeding in rice (Oryza sativa). For example, the aromatic rice varieties basmati and jasmine rice, with a popcorn‐like scent, are popular worldwide and routinely command a price premium. 2‐acetyl‐1‐pyrroline (2AP) is a key flavor compound among over 200 volatiles identified in fragrant rice. A naturally fragrant germplasm exists in multiple plant species besides rice, which all exhibit lower activity of BETAINE ALDEHYDE DEHYDROGENASE 2 (BADH2). However, no equivalent aromatic germplasm has been described in maize (Zea mays). Here, we characterized the two maize BADH2 homologs, ZmBADH2a and ZmBADH2b. We generated zmbadh2a and zmbadh2b single mutants and the zmbadh2a‐zmbadh2b double mutant by CRISPR/Cas in four inbred lines. A popcorn‐like scent was only noticeable in seeds from the double mutant, but not from either single mutant or in wild type. In agreement, we only detected 2AP in fresh kernels and dried mature seeds from the double mutant, which accumulated between 0.028 and 0.723 mg/kg 2AP. These results suggest that ZmBADH2a and ZmBADH2b redundantly participate in 2AP biosynthesis in maize, and represent the creation of the world's first aromatic maize by simultaneous genome editing of the two BADH2 genes.

Maintaining the morphology of electrode materials with high invertibility contributes to the prolonged cyclic stability of battery systems. However, the majority of electrode materials tend to degrade during the charge–discharge process owing to the inevitable increase in entropy. Herein, a self‐healing strategy is designed to promote morphology rejuvenation in Prussian blue analogue (PBA) cathodes by cobalt doping. Experimental characterization and theoretical calculations demonstrate that a trace amount of cobalt can decelerate the crystallization process and restore the cracked areas to ensure perfect cubic structures of PBA cathodes. The electric field controls the kinetic dynamics, rather than the conventional thermodynamics, to realize the “electrochemically driven dissolution–recrystallization process” for the periodic self‐healing phenomenon. The properties of electron transportation and ion diffusion in bulk PBA are also improved by the doping strategy, thus boosting the cyclability with 4000 cycles in a diluent electrolyte. This discovery provides a new paradigm for the construction of self‐healing electrodes for cathodes.

We have systematically studied physical properties of BaðFe 0.97 Cr 0.03 Þ 2 ðAs 1−x P x Þ 2 , where superconductivity in BaFe 2 ðAs 1−x P x Þ 2 is fully suppressed by just 3% of Cr substitution of Fe. A quantum critical point is revealed at x ∼ 0.42, where non-Fermi-liquid behaviors similar to those in BaFe 2 ðAs 1−x P x Þ 2 are observed. Neutron diffraction and inelastic neutron scattering measurements suggest that the quantum critical point is associated with the antiferromagnetic order, which is not of conventional spin-density-wave type as evidenced by the ω=T scaling of spin excitations. On the other hand, no divergence of lowtemperature nematic susceptibility is observed when x is decreased to 0.42 from higher doping level, demonstrating that there are no nematic quantum critical fluctuations. Our results suggest that non-Fermiliquid behaviors in iron-based superconductors can be solely resulted from the antiferromagnetic quantum critical fluctuations, which cast doubts on the role of nematic fluctuations played in the normal-state properties in iron-based superconductors.

Vanadium dioxide (VO2) exhibits an insulator-to-metal transition accompanied by a structural transition near room temperature. This transition can be triggered by an ultrafast laser pulse. Exotic transient states, such as a metallic state without structural transition, were also proposed. These unique characteristics let VO2 have great potential in thermal switchable devices and photonic applications. Although great efforts have been made, the atomic pathway during the photoinduced phase transition is still not clear. Here, we synthesize freestanding quasi-single-crystal VO2 films and examine their photoinduced structural phase transition with mega-electron-volt ultrafast electron diffraction. Leveraging the high signal-to-noise ratio and high temporal resolution, we observe that the disappearance of vanadium dimers and zigzag chains does not coincide with the transformation of crystal symmetry. After photoexcitation, the initial structure is strongly modified within 200 femtoseconds, resulting in a transient monoclinic structure without vanadium dimers and zigzag chains. Then, it continues to evolve to the final tetragonal structure in approximately 5 picoseconds. In addition, only one laser fluence threshold instead of two thresholds suggested in polycrystalline samples is observed in our quasi-single-crystal samples. Our findings provide essential information for a comprehensive understanding of the photoinduced ultrafast phase transition in VO2.

No abstract