Determination of Illegally Used Chemical Dyes in the Chinese Herbal Medicine "Red Flower Oil".

Background: Red flower oil is a group of herbal medicinal liniments widely used in China and Southeast Asia. The color of red flower oil is adjusted to red or brownish-red by adding natural dyes.

Objective: The objective of this study is to identify and quantify the synthetic dyes illegally used in red flower oil.

Analogue of Electromagnetically Induced Transparency in an All-Dielectric Double-Layer Metasurface Based on Bound States in the Continuum.

Bound states in the continuum (BICs) have attracted much attention due to their infinite Q factor. However, the realization of the analogue of electromagnetically induced transparency (EIT) by near-field coupling with a dark BIC in metasurfaces remains challenging. Here, we propose and numerically demonstrate the realization of a high-quality factor EIT by the coupling of a bright electric dipole resonance and a dark toroidal dipole BIC in an all-dielectric double-layer metasurface.

Analogue of electromagnetically induced transparency in a metal-dielectric bilayer terahertz metamaterial.

We realize and numerically demonstrate the analogue of electromagnetically induced transparency (EIT) with a high-Q factor in a metal-dielectric bilayer terahertz metamaterial (MM) via bright-bright mode coupling and bright-dark mode coupling. The dielectric MM with silicon dimer rectangular-ring-resonator (Si-DRR) supports either a bright high-Q toroidal dipole resonance (TD) or a dark TD with infinite Q value, while plasmonic MM with metallic rectangular-ring-resonator (M-RR) supports a low-Q electric dipole resonance (ED). The results show that the near-field coupling between the dark TD and bright ED behaves just as that between the two bright modes, which is dependent on the Q factor of the TD resonance.

Analogue of electromagnetically induced transparency with high-Q factor in metal-dielectric metamaterials based on bright-bright mode coupling.

Based on bright-bright mode coupling, we numerically demonstrated the analogue of electromagnetically induced transparency (EIT) with a high quality factor (Q) in a stacked metal-dielectric metamaterial (MM) in the near-infrared regime. The optical coupling between a high-Q toroidal dipole mode supported by a silicon rod array and a low-Q dipole mode supported by a silver strip array was investigated from the near-field to the far-field regimes. We realized and significantly enhanced the long-range coupling between the two resonance modes through the MM-induced Fabry-Pérot (FP) effect.

Screening of Chemical Dyes in Traditional Chinese Medicine by HPTLC-MS.

It has been uncovered that chemical dyes are illegally used in traditional Chinese medicines to brighten color and cover up inferiority, which threaten the safety of patients. In the present study, an HPTLC-MS method was developed for the effective screening of 11 chemical dyes (Sudan I, II, III, and IV; 808 Scarlet; Sudan Red 7B; malachite green; Basic Orange 2; auramine; Orange II; and erythrosine) in traditional Chinese medicine (TCM) raw materials and Chinese patent medicines. Firstly, unwashed HPTLC plates were chosen by comparing the background signals of the TLC plates used directly and prewashed with analytical grade and HPLC grade solvents.