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Phase Shifting Enhancement of a Substrate-Integrated Waveguide Phase Shifter Based on Liquid Crystal

by Hyun-Ji Shin, Jun-Seok Ma, Jin-Young Choi and Wook-Sung Kim

Appl. Sci. 2023, 13(4), 2504; https://doi.org/10.3390/app13042504 - 15 Feb 2023

Cited by 6 | Viewed by 3140

A novel technique to enhance the phase shifting range of a liquid crystal (LC)-based, substrate-integrated waveguide (SIW) phase shifter by inserting inductive posts (IPs) is presented for the first time. The IPs inserted in the LC-based SIW phase shifter produce a phase advance based on the relative permittivity of the LC, resulting in an additional differential phase shift. At 28 GHz, the proposed structure with IPs achieves a ratio of maximum differential phase shift (

∆ ϕ_{m a x}

) to maximum insertion loss

{(I L}_{m a x})

(FoM1) = 52.82

° / d B

and ratio of maximum differential phase shift to length (FoM2) = 2.62

° / m m

. Compared with conventional LC-based SIW phase shifters that lack an IP and use the same amount of LC, the FoM1 increased by 16% and the FoM2 increased by 55%. In addition, compared to the typical structure that uses additional LCs instead of IPs, the FoM1 decreased by 7%, and FoM2 increased by 21%. Therefore, inserting IPs into the LC-based SIW phase shifter can reduce the dimensions of the phase shifter and the amount of LCs required to achieve the desired differential phase shift. We believe this work can contribute to the design of compact and efficient SIW phase shifters for future telecommunication systems. Full article

(This article belongs to the Special Issue Liquid Crystal Thin Films: Structures and Applications)

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12 pages, 2296 KB

Open AccessArticle

L-Menthol-Loadable Electrospun Fibers of PMVEMA Anhydride for Topical Administration

by Amalia Mira, Marta Rubio-Camacho, David Alarcón, Enrique Rodríguez-Cañas, Asia Fernández-Carvajal, Alberto Falco and Ricardo Mallavia

Pharmaceutics 2021, 13(11), 1845; https://doi.org/10.3390/pharmaceutics13111845 - 3 Nov 2021

Cited by 8 | Viewed by 3127

Abstract

Poly(methyl vinyl ether-alt-maleic anhydride) (PMVEMA) of 119 and 139 molecular weights (P119 and P139, respectively) were electrospun to evaluate the resulting fibers as a topical delivery vehicle for (L-)menthol. Thus, electrospinning parameters were optimized for the production of uniform bead-free fibers from 12% w/w PMVEMA (±2.3% w/w menthol) solutions, and their morphology and size were characterized by field emission scanning electron microscopy (FESEM). The fibers of P119 (F₁₁₉s) and P139 (F₁₃₉s) showed average diameter sizes of approximately 534 and 664 nm, respectively, when unloaded, and 837 and 1369 nm when loaded with menthol. The morphology of all types of fibers was cylindrical except for F₁₃₉s, which mostly displayed a double-ribbon-like shape. Gas chromatography-mass spectrometry (GC-MS) analysis determined that not only was the menthol encapsulation efficiency higher in F₁₃₉s (92% versus 68% in F₁₁₉s) but also that its stability over time was higher, given that in contrast with F₁₁₉s, no significant losses in encapsulated menthol were detected in the F₁₃₉s after 10 days post-production. Finally, in vitro biological assays showed no significant induction of cytotoxicity for any of the experimental fibers or in the full functionality of the encapsulated menthol, as it achieved equivalent free-menthol levels of activation of its specific receptor, the (human) transient receptor potential cation channel subfamily M (melastatin) member 8 (TRPM8). Full article

(This article belongs to the Special Issue Design of Novel Polymeric Systems for Controlled Drug Delivery)

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