Siji-kangbingdu mixture is an anti-inflammatory, anti-bacterial, and anti-viral herbal mixture which is frequently used by doctors to treat upper respiratory infections. It’s important to establish an efficient and economical quality-control method to ensure the quality consistency and efficacy stability of Siji-kangbingdu mixture. In this study, an integrated multi-evaluation method was established, sequentially involving UPLC-TripleTOF-MS analysis, UPLC fingerprint analysis, and the quantitative analysis of multi-components using the single-marker (QAMS) method. With one chromatographic condition, a total of 71 compounds were identified by MS and MS/MS information, with a mass error of less than 5 ppm; 49 peaks detected in 254 nm were selected to establish the fingerprint similarity model, and 7 chemical compounds were simultaneously determined, namely, chlorogenic acid, liquiritin, rutin, isochlorogenic acid A, forsythin, forsythoside A, and glycyrrhizic acid, with forsythoside A as the reference standard. There was no significant difference in the content of the seven compounds between the QAMS method and the external standard method (ESM). The established multi-evaluation method will largely promote the quality control and standardization process of Siji-kangbingdu mixture. It also provides a reference workflow for the overall evaluation of TCM patent medicines, from chemical profiling to fingerprint and quantitative analysis.
It is necessary to explore the potential applications of surface plasmon polaritons (SPPs) on graphene metasurfaces and enhance the performance of their on-off modulators and slow-light effect. A simple monolayer graphene metasurface is developed for achieving the plasmon-induced transparency (PIT) phenomenon in the terahertz range. PIT can be effectively tuned by the positional parameter, the Fermi level, and the carrier mobility using the finite-difference time-domain (FDTD). Moreover, it is found that a quad-frequency on-off modulator and an outstanding slow-light effect can be realized in this proposed metasurface. Interestingly, modulation depth (MD), insertion loss (IL), ΔT, and the group index are of 98.90%, %0.05 dB, 0.97, and 3383, respectively. Hence, the results show that the proposed metasurface has excellent performance for on-off modulators and a slow-light effect, which can provide theoretical guidance for designing terahertz micro-nanophotonic devices.
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