Using quasi-bound states in the continuum in an all-dielectric metasurface array to enhance terahertz fingerprint sensing.

The terahertz absorption fingerprint spectrum is crucial for qualitative spectral analysis, revealing the rotational or vibrational energy levels of numerous biological macromolecules and chemicals within the THz frequency range. However, conventional sensing in this band is hindered by weak interactions with trace analytes, leading to subtle signals. In this Letter, an all-dielectric metasurface array is proposed to enhance the absorption fingerprint spectrum using quasi-bound states in the continuum (BIC) resonance. The observable quasi-BIC resonance is achieved by breaking the symmetry of the C2v structure. The periodic dimensions of the structure are adjusted to excite quasi-BIC resonances at different frequencies, thereby enhancing the fingerprint spectra of four different substances. By exploiting the correlation between the Q-factor and absorption across different frequencies, calibration of the molecular absorption fingerprint spectrum obtained through metasurface sensing yields precise enhanced absorption fingerprint spectra for various substances within the 0.55-1.6 THz range. Our Letter introduces a novel, to the best of our knowledge, strategy for trace sensing in the THz frequency range, demonstrating the promising potential for enhanced absorption fingerprint spectrum sensing.

Coupling-Based Multiple Bound States in the Continuum and Grating-Assisted Permittivity Retrieval in the Terahertz Metasurface.

The terahertz (THz) metasurfaces that support bound states in the continuum (BICs) provide a promising platform for various applications due to their high Q-factor resonance. In this study, we experimentally demonstrate multiple BICs with different resonance symmetries in the THz metasurface based on mode coupling. The proposed metasurface is composed of 2 × 2 split ring resonators (SRRs) metamolecules. The SRRs of two different gap angles in the metamolecule lattice provide intrinsic resonance with different frequencies, and the coupling between them exhibits high transmission quasi-BIC resonance, which can be tuned by varying the gap angle. The arrangement of SRRs in the 2 × 2 metamolecule lattice determines the types of coupling that govern the resonance symmetry of quasi-BIC. More interestingly, the multiple quasi-BICs enabled by different couplings can be simultaneously achieved in a metasurface. Apart from tuning the gap angles, the permittivity in the vicinity of SRRs also changes the resonance frequency. Consequently, quasi-BIC can be artificially formed by deliberately constructing the permittivity difference of the dielectric environment on the SRRs. In view of this, we introduce the scheme of permittivity retrieval for the dispersive analyte, assisted by the fixed-permittivity gratings. In addition, we experimentally demonstrate the metasurface in combination with the microfluidic chip for the sensing of the glucose solution concentration. Our findings offer a possible strategy for the existing manufactured metasurface to achieve quasi-BIC resonance and provide a promising candidate for approaching the spectral analysis of the biochemical.

Broussonin E against acute respiratory distress syndrome: the potential roles of anti-inflammatory.

We applied network pharmacology and molecular docking analyses to study the efficacy of Broussonin E (BRE) in acute respiratory distress syndrome (ARDS) treatment and to determine the core components, potential targets, and mechanism of action of BRE. The SwissTargetprediction and SEA databases were used to predict BRE targets, and the GeneCards and OMIM databases were used to predict ARDS-related genes. The drug targets and disease targets were mapped to obtain an intersecting drug target gene network, which was then uploaded into the String database for protein-protein interaction network analysis. The intersecting gene was also uploaded into the DAVID database for gene ontology enrichment analysis and Kyoto encyclopedia of genes and genomes pathway analysis. Molecular docking analysis was performed to verify the interaction of BRE with the key targets. Finally, to validate the experiment in vivo, we established an oleic acid-induced ARDS rat model and evaluated the protective effect of BRE on ARDS by histological evaluation and enzyme-linked immunosorbent assay. Overall, 79 targets of BRE and 3974 targets of ARDS were predicted, and 79 targets were obtained after intersection. Key genes such as HSP90AA1, JUN, ESR1, MTOR, and PIK3CA play important roles in the nucleus and cytoplasm by regulating the tumor necrosis factor, nuclear factor-κB, and PI3K-Akt signaling pathways. Molecular docking results showed that small molecules of BRE could freely bind to the active site of the target proteins. In vivo experiments showed that BRE could reduce ARDS-related histopathological changes, release of inflammatory factors, and infiltration of macrophages and oxidative stress reaction. BRE exerts its therapeutic effect on ARDS through target and multiple pathways. This study also predicted the potential mechanism of BRE on ARDS, which provides the theoretical basis for in-depth and comprehensive studies of BRE treatment on ARDS.

Observation of the bound states in the continuum supported by mode coupling in a terahertz metasurface.

Metasurface supporting bound states in the continuum (BIC) provides a unique approach for the realization of intense near-field enhancement and high quality factor (Q-factor) resonance, which promote the advancement of various applications. Here we experimentally demonstrate a Friedrich-Wintgen BIC based on the mode coupling in the terahertz metasurface, which produces BIC by the coupling of the LC mode and dipole mode resonances. The transition from ideal BIC to quasi-BIC is caused by the mismatch of the coupling, and the mode decay rate during this process is analyzed by temporal coupled mode theory. The Q-factor and the electric field enhancement of the quasi-BIC resonance are significantly increased, which provides enormous potential in sensing, nonlinear optics, and topological optics.

Glabridin attenuates endothelial dysfunction and permeability, possibly via the MLCK/p-MLC signaling pathway.

Atherosclerosis is caused by various factors, and Glabridin may have protective effects on the cardiovascular system. The purpose of the present study was to evaluate the effects of Glabridin on atherosclerosis and evaluate whether Glabridin attenuates arteriosclerosis and endothelial permeability by suppressing the myosin light chain (MLC) kinase (MLCK)/phosphorylated (p)-MLC system via the mitogen activated protein kinase (MAPK) signaling pathway. Male New Zealand rabbits were randomly divided into 3 groups: The control group was administered an ordinary diet, whereas the high fat group and the Glabridin (2 mg/kg/d) intervention group were administered a high fat diet. Following 12 weeks, the blood lipid levels of rabbits, the morphological structure of the arterial wall, the arterial intimal permeability, the endothelial function and the mRNA levels of MLCK were measured. Western blot analysis was used to detect the levels of MLCK, p-c-Jun N-terminal kinase (JNK), p-extracellular signal regulated kinase (ERK), and p-p38. The high-fat diet group exhibited significantly increased total cholesterol and triglycerides, and endothelial dysfunction, which were attenuated by Glabridin treatment. Notably, the aortic endothelial permeability was increased in the high-fat diet group but was ameliorated in the Glabridin treatment group. Hyperlipidemia enhanced the expression of p-MLC and MLCK, which were associated with the increased phosphorylation of ERK, p38 and JNK. These changes were also ameliorated by Glabridin. In conclusion, the results of the present study suggested that atherosclerosis may be associated with upregulated MLCK expression and activity, which was downregulated by Glabridin. The mechanism of action of Glabridin was thought to proceed through modulating MAPK pathway signal transduction. However, further studies are required to adequately illuminate the exact regulatory mechanisms involved.