We report a method of broadening the reflection bandwidth of polymer-stabilized cholesteric liquid crystal (PSCLC). The top substrate was consecutively coated with a polyimide (PI) and a reactive mesogen (RM) layer, while the bottom substrate was coated with only PI. We exposed the top substrate with the RM coating to UV light. The reflection bandwidth of the PSCLC samples where the top substrate was over-coated with RM was significantly broader than the samples where both substrates were coated with PI. In addition to the effect of the UV intensity gradient, the RM-coated top substrate has a chemical affinity to bulk RM, promoting formation of the pitch gradient and broadening the reflection bandwidth in the sample.
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http://dx.doi.org/10.1364/AO.56.005731 | DOI Listing |
J Mol Model
January 2025
Nanjing Hydraulic Research Institute, Shanghai, China.
Context: This study systematically investigated the effects of single S-atom vacancy defects and composite defects (vacancy combined with doping) on the properties of MoS using density functional theory. The results revealed that N-doped S-vacancy MoS has the smallest composite defect formation energy, indicating its highest stability. Doping maintained the direct band gap characteristic, with shifts in the valence band top.
View Article and Find Full Text PDFMaterials (Basel)
January 2025
State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China.
The integration, miniaturization, and high frequency of microwave vacuum electronics put forward higher requirements for heat-conducting and wave-absorbing integrated materials. However, these materials must balance the dispersion and isolation of wave-absorbing components to optimize absorption while maintaining the continuity of thermal conductivity pathways with low defect rates and minimal interfaces. This presents a significant challenge in achieving both high thermal conductivity and efficient wave absorption simultaneously.
View Article and Find Full Text PDFMicromachines (Basel)
December 2024
Department of Applied Mechanics, FEMTO-ST Institute, CNRS, University of Franche-Comté, F-25000 Besançon, France.
An electromagnetic vibration energy harvester with a 2:1:2 internal resonance (IR) is proposed, allowing for the simultaneous activation of two IRs within the system in order to enhance its performance in terms of bandwidth and harvested power. The device consists of three magnetically coupled oscillators separated by an adjustable gap to tune the system eigenfrequencies and achieve a 2:1:2 IR. Numerical investigations are conducted to predict the behavior of the proposed device, and a multi-objective optimization procedure is employed to enhance the harvester's performance by introducing mass perturbations.
View Article and Find Full Text PDFSci Rep
January 2025
Electrical Engineering Department, Tarbiat Modares University, Tehran, Iran.
This article presents the design of a novel ultra-wideband, thin metamaterial linear cross-polarization converter (CPC) operating at microwave frequencies. The CPC consists of two concentric deformed rings on a dielectric substrate backed by a metallic surface. It demonstrates co-polarization and cross-polarization reflection coefficients below - 11 and above - 1.
View Article and Find Full Text PDFSmall
January 2025
Key Laboratory of Aerospace Materials and Performance (Ministry of Education) School of Materials Science and Engineering, Beihang University, No.37 Xueyuan Road, Beijing, 100191, P. R. China.
A reasonable construction of hollow structures to obtain high-performance absorbers is widely studied, but it is still a challenge to select suitable materials to improve the low-frequency attenuation performance. Here, the FeO@C@NiO nanoprisms with unique tip shapes, asymmetric multi-path hollow cavity, and core-shell heteroepitaxy structure are designed and synthesized based on anisotropy and intrinsic physical characteristics. Impressively, by changing the load of NiO, the composites achieve strong absorption, broadband, low-frequency absorption: the reflection loss of -55.
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