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This article explores the concept of function assignment in first language (L1) and second language (L2) speech production, compares automation of function assignment in L1 and L2 speech production, pursues factors hampering automation of function assignment in L2 speech production, and discusses how to improve automation of function assignment in L2 speech production. Grammatical encoding, of which function assignment is one of the subordinate processes, is also one of the processes in L2 speech production. While function assignment in L1 speech production is mostly automatic, it demands much attentional resources and is executed under conscious supervision in L2 speech production. L2 learners’ incomplete knowledge of the target language and their limited working memory resources hamper automation of function assignment in L2 speech production. Furthermore, as per generative models of learning, to improve automation of function assignment, teachers can either adopt strategies or improve instructional designs targeting this subprocess. Together, this conceptual paper gives a comprehensive overview of automation of function assignment, explores its impact on second language acquisition (SLA), and reveals that it is feasible to facilitate automation of function assignment in L2 speech production by improving instructional designs, especially the presentation methods of sentence elements.

High reaction activity and cycling stability are essential to commercialize electrodes for vanadium flow batteries (VFBs) and zinc–bromine flow batteries (ZBFBs). In this work, a sandwich-like multi-scale pore-rich hydroxylated carbon (SPHC), which is made of a highly activated porous middle layer assembled between a pair of protuberance-rich compact outer layers, was proposed and developed to meet both the redox reactions and the mass-charge transport in flow batteries. In this SPHC, (i) the middle layer with the pore-opened integrated structure provides abundant active sites for redox reactions, (ii) the outer layer with a compact surface protects the inside pores against the electrolyte flow, and (iii) the even-distributed protuberances in the outer layer further increase the number of reaction sites. Due to the sandwich-like porous structure that possesses abundant hydroxyl functional groups (25.3%) and a high specific surface area (313.2 m2 g−1), the SPHC demonstrates both high electrochemical activity and stability towards vanadium and bromine redox reactions. Additionally, the SPHC-based electrode yields energy efficiencies as high as 77.8% at 200 mA cm−2 in VFBs and 76.1% at 80 mA cm−2 in ZBFBs, 28.3% and 8.2% higher than that of a pristine electrode, respectively. More impressively, the SPHC electrode in VFBs has an ultra-low energy efficiency decay of 0.0025% per cycle for over 500 charge–discharge cycles. This work provides a promising approach to develop a high-activity and high-stability electrode that enables great potential applications in flow batteries and other electrochemical energy storage systems.

The uniform pH reaction environment of both acid proton-exchange membrane and alkaline anion-exchange membrane direct liquid fuel cells (DLFCs) substantially lowers the cell performance. Herein we propose a high-performance pH-disparate DLFC (ΔpH-DLFC), which can harvest the neutralization energy to maximize the thermodynamic voltage of DLFCs. Benefiting from the construction of oxygen-electrolyte interfaces, the triple-phase boundary density of cathode is significantly increased. The ΔpH-DLFCs yield peak power densities of 279, 341 and 610 mW cm−2 when methanol, ethanol and sodium formate are fed into the anode respectively. The stable operation of direct formate fuel cell at 200 mA cm−2 for 24 h further confirms the feasibility of the ΔpH-DLFCs. Moreover, the flexibility of the ΔpH-DLFC in oxidants and catalysts was also investigated. The experimental result indicates that the air-based pH-disparate direct formate fuel cell with non-platinum catalyst obtains a peak power density of 140 mW cm−2 at 80 °C, suggesting the great potential for practical application.