Investigation of perfect narrow-band absorber in silicon nano hole array.

In this paper, we proposed a triple layer structure consisting of the bottom silver layer, thin silicon oxide space layer, and ultrathin semiconductor silicon film with nano hole array achieving three absorption peaks with narrow band. The absorption spectrum can be easily controlled by adjusting the structural parameters including the radius and period of the nano hole array, and the maximal absorption can reach 99.0% and the narrowest full width of half maximum can reach about 6.5 nm in theory. We also clarified the physical mechanism of the proposed structure in details by finite-difference time-domain simulation, in which the three narrow band perfect adsorption peaks can be attributed to electric dipole resonance, magnetic dipole resonance and plasmonic resonance respectively. At the same time, we used a low-cost nanosphere lithography method to fabricate the proposed nano hole array in large area. In experiment, the absorption peak of the proposed triple layer structure can reach up to 98.3% and the narrowest full width of half maximum can reach up to about 10.1 nm. The highest quality factor Q can reach up to 98.4. This work can open a new avenue for high-quality factor narrow band perfect absorption using ultrathin semiconductor film and benefit for many fields such as infrared sensors, plasmonic filters, and hyperspectral imaging.

All-Dielectric Gratings with High-Quality Structural Colors.

We present a dual-layer hafnium dioxide (HfO2) grating capable of full-color modulation in the visible spectrum by leveraging the magnetic dipole resonance induced by the lower-layer HfO2 grating, while the upper-layer HfO2 grating serves as a refractive index matching layer to effectively suppress high-order Mie resonances at shorter wavelengths. The HfO2/HfO2 grating exhibits a significantly larger distribution area in the CIE 1931 chromaticity diagram compared to the HfO2 grating. Furthermore, the structural color saturation closely approximates that of monochromatic light. Under varying background refractive index environments, this structure consistently exhibits high-quality structural color. However, the hue of the structural color undergoes alterations. When the polarization angle is below 20°, the saturation of the acquired structural color remains remarkably consistent. However, exceeding 20° results in a significant degradation in the quality of the structural color. This study demonstrates the promising potential for diverse applications, encompassing fields such as imaging and displays.

Design, synthesis, and biological studies of novel sulfonamide derivatives as farnesoid X receptor agonists.

Farnesoid X receptor (FXR) is considered as a promising target for the treatment of NASH. Although many non-steroidal FXR agonists have been reported, the structure types are quite scarce and mainly limited to the isoxazole scaffold derived from GW4064. Therefore, it is crucial to expand the structure types of FXR agonist to explore wider chemical space. In this study, the structure-based scaffold hopping strategy was performed by hybrid FXR agonist 1 and T0901317, which resulted in the discovery of sulfonamide FXR agonist 19. Molecular docking study reasonably explained the SAR in this series, and compound 19 fitted well with the binding pocket in a similar mode to the co-crystal ligand. In addition, compound 19 exhibited considerable selectivity against other nuclear receptors. In NASH model, compound 19 alleviated the typical histological features of fatty liver, including steatosis, lobular inflammation, ballooning, and fibrosis. Moreover, compound 19 exhibited acceptable safety profiles with no acute toxicity to major organ. These results suggested that the novel sulfonamide FXR agonist 19 might be a promising agent for the treatment of NASH.