Tunable broadband terahertz absorber based on plasmon hybridization in monolayer graphene ring arrays.

Graphene as a new two-dimensional material can be utilized to design tunable optical devices owing to its exceptional physical properties, such as high mobility and tunable conductivity. In this paper, we present the design and analysis of a tunable broadband terahertz absorber based on periodic graphene ring arrays. Due to plasmon hybridization modes excited in the graphene ring, the proposed structure achieves a broad absorption bandwidth with more than 90% absorption in the frequency range of 0.88-2.10 THz under normal incidence, and its relative absorption bandwidth is about 81.88%. Meanwhile, it exhibits polarization-insensitive behavior and maintains high absorption over 80% when the incident angle is up to 45° for both TE and TM polarizations. Additionally, the peak absorption rate of the absorber can be tuned from 21% to nearly 100% by increasing the graphene's chemical potential from 0 to 0.9 eV. Such a design can have some potential applications in various terahertz devices, such as modulators, detectors, and spatial filters.

High Photon Absorptivity of Quantum Dot Infrared Photodetectors Achieved by the Surface Plasmon Effect of Metal Nanohole Array.

With the increasing demand for small-scale photodetector devices, quantum dot-based infrared photodetectors have attracted more and more attention in the past decades. In this work, periodic metal nanohole array structures are introduced to the quantum dot infrared photodetectors to enhance the photon absorptivity performance via the surface plasmon enhancement effect in order to overcome the bottleneck of low optical absorption efficiency that exists in conventional photodetectors. The results demonstrate that the optimized metal nanohole array structures can greatly enhance the photon absorptivity up to 86.47% in the specific photodetectors, which is 1.89 times than that of conventional photodetectors without the metal array structures. The large enhancement of the absorptivity can be attributed to the local coupling surface plasmon effect caused by the metal nanohole array structures. It is believed that the study can provide certain theoretical guidance for high-performance nanoscale quantum dot-based infrared photodetectors.

Sinomenine's protective role and mechanism in stress load-induced heart failure.

OBJECTIVES: This study is designed to investigate the effects and mechanisms of sinomenine (Sin) in stress load-induced heart failure in mice. METHODS: We used aortic constriction (AB) to cause pressure overload as our heart failure model. Sin was received in mice as the treatment group. Cardiac function and structural changes were detected using echocardiography. Heart-lung mass ratios were measured. The serum levels of IL-10 and IL-17 proteins were detected by using ELISA, cardiac hypertrophy markers atrial natriuretic peptide (ANP), myocardial I and III collagen mRNA levels were detected by RT-PCR. Myocardial type I and III collagen protein levels were detected by Western blotting. KEY FINDINGS: Sin significantly improved stress load-induced heart failure (P < 0.05), reduced the heart-lung mass ratio, ANP, collagen-I and -III mRNA and protein levels (P < 0.05); Sin can enhance the ratio of IL-10/IL-17. CONCLUSION: Sin may be a promising drug target to improve heart failure. Its role is related to reduce serum ANP levels, inhibit the mRNA and protein level of type I and III collagen and enhance the ratio of IL-10/IL-17.

Theoretical investigation of a five-band terahertz absorber based on an asymmetric split-ring resonator.

A simple five-band terahertz metamaterial perfect absorber, composed of an asymmetric double-gap square split ring and a metallic ground plate spaced by a thin polyimide dielectric layer, is proposed and theoretically investigated. The results show that it can perform absorption peaks at five resonant frequencies whose peaks average 98.85%. The perfect absorption is mainly attributed to the combined effect of LC, dipole, and surface response of the structure. Compared to previously reported multiband absorbers, our design only has a single and compact structure, which can drastically simplify the design and fabrication process. Furthermore, the resonance absorption properties of the absorber can be tuned by changing the geometric parameters of the structure. Such a simple and effective design holds great promise for potential applications in spectroscopic imaging, biological sensing, and detecting of drugs and explosives.