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411 results on '"Zhang, Xiao-Qin"'

108. Dual-band terahertz metamaterial absorber based on H-shape and double-SRR structure

Author

Zhang Xiao Qin, Wei Yan Yu, Huang Ao, and Yang Kuo

Subjects
Materials science, business.industry, Terahertz radiation, Far-infrared laser, Physics::Optics, Metamaterial, Terahertz spectroscopy and technology, Photomixing, Resonator, Optics, Metamaterial absorber, Optoelectronics, business, Absorption (electromagnetic radiation)
Abstract

Composite structures of dual-band metamaterials in the terahertz regime are proposed, which are based on the H shape and double splitting resonator (DSRR) structure. Simulation results show that it can perform absorption peaks at one resonant frequency 0.43 THz with the absorption more than 95%, and at two distinct resonant frequencies 0.84 THz with the absorption more than 85%. Furthermore, the resonance mechanism is studied using equivalent circuits, which is well agree with the simulation results. These models have the advantages of simple structure and strong resonance, which indicate potentially application in the design of multiband terahertz devices.

Published
2015
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109. Dammarane-Type Triterpenoids from the Roots of Rhus chinensisand Their Preventive Effects on Zebrafish Heart Failure and Thrombosis

Author

Ye, Miao, Xu, Wen, He, Da-Qing, Wu, Xian, Lai, Wen-Fang, Zhang, Xiao-Qin, Lin, Yu, Xu, Wei, and Li, Xu-Wen

Abstract

Eight new dammarane-type triterpenoids (1–8), together with a related known analogue (9), were isolated from the roots of Rhus chinensis, a traditional Chinese medicine for treating coronary artery heart disease, guided by LC-MS analysis. Their structures were elucidated based on extensive spectroscopic analysis and quantum chemical calculations. Notably, compounds 1–7and 9possess an unusual 17α-side chain, and 1–4, 6, and 9contain an uncommon 3-methyl-5,6-dihydro-2H-pyran-2-one moiety in the side chain. Compounds 1–5and 9have a 3,19-hemiketal bridge in the A ring. In an in vivo bioassay, 1, 2, and 4–6exhibited significant preventive effects on zebrafish heart failure at 0.5 μg/mL, improving heart dilatation, venous congestion, cardiac output, blood flow velocity, and heart rate. Compound 5, displaying the most promising heart failure preventive activities, showed even better effects on increasing cardiac output (72%) and blood flow velocity (83%) than six first-line heart failure therapeutic drugs. Moreover, 1, 2, and 6prevented the formation of thrombosis in zebrafish at 0.5 μg/mL. The present investigation suggests that the new dammarane triterpenoids might be partially responsible for the utility of R. chinensisin treating coronary artery heart disease.

Published
2020
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115. Predicting the influence of future climate change on the suitable distribution areas of Elaeagnus angustifolia.

Author

ZHANG Xiao-qin, LI Guo-qing, and DU Sheng

Abstract

Climate change significantly affects geographic distribution of plants worldwide. Understanding the influence of climate change on the suitable areas of afforestation tree species in China and taking timely countermeasures are crucial for improving the effectiveness of afforestation. Elaeagnus angustifolia is a good species for ecological restoration of degraded lands and control of desertification. Using MaxEnt and GIS, we predicted the changes of climatically suitable areas of this species under future climate scenarios, based on 182 records from herbaria and published literatures, and 13 climatic factors from BIOCLIM, Hofdridge life zone and Kira index. The results showed that the four climate scenarios in 2070s had different effects on the climatically suitable areas of this species. The suitable areas would shrink in the lowest greenhouse gas emission (RCP 2.6) scenario. The shrinking areas were mainly located in the edge of the currently suitable areas in the northwest. The suitable areas would expand in the lower (RCP 4.5), the higher (RCP 6.0) and the highest (RCP 8.5) greenhouse gas emission scenarios. The expanding areas were mainly located in the northwestern arid regions of warm temperate zone, and northeastern sub-humid regions of middle temperate zone. There were obvious expansions in the northern arid and semi-arid regions of middle temperate zone, and southern humid regions of north-subtropieal zone under RCP 8.5 scenario. The geographical centrofds of future suitable ranges would move with a speed of 6-19 km µ (10 a)-1. The altitudinal centrofds were predicted to move to lower regions with a speed of 3- 20 m µ (10 a)-1. The stably suitable areas accounted for 83%-98% of the current distribution ranges of this species, which were generally stable under iuture climate change scenarios. [ABSTRACT FROM AUTHOR]

Published
2018
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