Electrolyte gating with ionic liquids (IL) on correlated vanadium dioxide (VO 2 ) nanowires/beams is effective to modulate the metal-insulator transition (MIT) behavior. While for macrosize VO 2 fi lm, the gating treatment shows different phase modulation process and the intrinsic mechanism is still not clear, though the oxygen-vacancy diffusion channel is always adopted for the explanation. Herein, the dynamic phase modulation of electrolyte gated VO 2 fi lms is investigated and the oxygen vacancies formation, diffusion, and recovery at the IL/oxide interface are observed. As a relatively slow electrochemical reaction, the gating effect gradually permeates from surface to the inside of VO 2 fi lm, along with an unsynchronized changes of integral electric, optical, and structure properties. First-principles-based theoretical calculation reveals that the oxygen vacancies can not only cause the structural deformations in monoclinic VO 2 , but also account for the MIT transition by inducing polarization charges and thereby adjusting the d-orbital occupancy. The fi ndings not only clarify the oxygen vacancies statement of electrolyte gated VO 2 fi lm, but also can be extended to other ionic liquid/oxide systems for better understanding of the surface electrochemical stability and electronic properties modulation.
Liuwei Dihuang Wan (LDW), a classic Chinese medicinal formula, has been used to improve or restore declined functions related to aging and geriatric diseases, such as impaired mobility, vision, hearing, cognition, and memory. It has attracted increasing attention as one of the most popular and valuable herbal medicines. However, the systematic analysis of the chemical constituents of LDW is difficult and thus has not been well established. In this paper, a rapid, sensitive, and reliable ultra-performance LC with ESI quadrupole TOF high-definition MS method with automated MetaboLynx analysis in positive and negative ion mode was established to characterize the chemical constituents of LDW. The analysis was performed on a Waters UPLC™ HSS T3 using a gradient elution system. MS/MS fragmentation behavior was proposed for aiding the structural identification of the components. Under the optimized conditions, a total of 50 peaks were tentatively characterized by comparing the retention time and MS data. It is concluded that a rapid and robust platform based on ultra-performance LC with ESI quadrupole TOF high-definition MS has been successfully developed for globally identifying multiple constituents of traditional Chinese medicine prescriptions. This is the first report on the systematic analysis of the chemical constituents of LDW.
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