In this work, we propose broadband and switchable terahertz (THz) polarization converters based on either graphene patch metasurface (GPMS) or its complementary structure (graphene hole metasurface, GHMS). The patch and hole are simply cross-shaped, composed of two orthogonal arms, along which plasmonic resonances mediated by Fabry-Perot cavity play a key role in polarization conversion (PC). An incidence of linear polarization will be converted to its cross-polarization (LTL) or circular polarization (LTC), as the reflected wave in the direction of two arms owning the same amplitude and π phase difference (LTL), or ±π/2 phase difference (LTC). Such requirements can be met by optimizing the width and length of two arms, thickness of dielectric layer, and Fermi level EF of graphene. By using GPMS, LTL PC of polarization conversion ratio (PCR) over 90% is achieved in the frequency range of 2.92 THz to 6.26 THz, and by using GHMS, LTC PC of ellipticity χ ≤ −0.9 at the frequencies from 4.45 THz to 6.47 THz. By varying the Fermi level, the operating frequency can be actively tuned, and the functionality can be switched without structural modulation; for instance, GPMS supports LTL PC as EF = 0.6 eV and LTC PC of χ ≥ 0.9 as EF = 1.0 eV, in the frequency range of 2.69 THz to 4.19 THz. Moreover, GHMS can be optimized to sustain LTL PC and LTC PC of |χ| ≥ 0.9, in the frequency range of 4.96 THz to 6.52 THz, which indicates that the handedness of circular polarization can be further specified. The proposed polarization converters of broad bandwidth, active tunability, and switchable functionality will essentially make a significant progress in THz technology and device applications, and can be widely utilized in THz communications, sensing and spectroscopy.
BackgroundThe relationship between anemia and outcomes after radiotherapy has not been systematically addressed. The study aimed to assess the prevalence and prognostic value of anemia in patients receiving primary radiotherapy for esophageal squamous cell carcinoma (ESCC).MethodsA total of 103 patients with ESCC were retrospectively reviewed. Anemia was defined as a hemoglobin level <12 g/dl for men and <11 g/dl for women. The 3-year and 5-year overall survival (OS) and disease-free survival (DFS) were analyzed between the anemic and non-anemic groups using the Kaplan-Meier method and the Cox proportional hazards model.ResultsNo significant differences were observed in patient characteristics between the anemic and non-anemic groups. The prevalence of anemia was 29.1%. The 3-year and the 5-year OS were 43% and 37%, respectively, in the non-anemic group, and 20% and 17%, respectively, in the anemic group. The 3-year and the 5-year DFS were 37% and 26%, respectively, in the non-anemic group, and 13% and 10%, respectively, in the anemic group. Survival analysis using the Kaplan-Meier method showed that there was significant difference between anemia and non-anemia (P < 0.02). In a multivariate analysis, anemia was identified as a highly significant prognostic factor for 3-year OS (hazard ratio 1.916; P = 0.012) and 3-year DFS (hazard ratio 1.973; P = 0.007), independent of T stage and the status of lymph nodes, and 5-year OS (hazard ratio 1.705; P = 0.027) and 5-year DFS (hazard ratio 1.980; P = 0.005), independent of TNM stage and the status of lymph nodes.ConclusionsAnemia before primary radiotherapy was associated with poor prognosis and an increased risk of relapse, which may serve as a new prognostic factor for ESCC.
Rock bursts have recently become a serious problem in the horizontal section mining of steeply inclined extra-thick coal seams (SIETCSs). However, few studies have been carried out to investigate their mechanisms and prevention. In this study, numerical simulation and field measurements were carried out to investigate the mechanism of rock bursts in the horizontal section mining of an SIETCS. A Universal Distinct Element Code (UDEC) Trigon model was built, based on the Yaojie No.3 Coal Mine, and calibrated through laboratory tests and RQD methods. The results demonstrate that the coal in the elastic zone around the roof is in a high static stress state, due to the asymmetric clamping and squeezing of the roof and floor. Strong dynamic loads are formed by breakage of the roof and the failure of multiple hinged beam structures during the evolution process of the overlying strata. Rock bursts occur on the roof side when the superimposition of the static stress σs and stress increment σd induced by such dynamic loads is greater than the critical stress σmin of the coal and rock. We propose a technical prevention scheme for the considered mine. Field studies suggest that the proposed technology can effectively prevent and control rock bursts in the horizontal section mining of SIETCSs.
Graphene and its relatives, such as bilayer and trilayer graphene, are promising plasmonic materials. Very recently, graphene has been demonstrated to be precisely folded (Chen et al 2019 Science 365 1036–40), thus folded graphene provides another appealing platform for plasmonics. In folded graphene nanodisks, we find fundamental dipole modes (DMs) will exhibit mode splitting, with one parallel and another perpendicular to the folding axis. The two DMs show differences in field patterns and folding angle dependence, but they both can be tuned by the size of structures and the Fermi level of graphene. Some interesting high order modes are introduced as well, which can be further engineered by folding. Our studies enrich the current research of graphene plasmonics, and pave the way for particular plasmonic device applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.