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Rationale: Endothelial dysfunction plays an integral role in pulmonary hypertension (PH). AMPK (AMP-activated protein kinase) and ACE2 (angiotensin-converting enzyme 2) are crucial in endothelial homeostasis. The mechanism by which AMPK regulates ACE2 in the pulmonary endothelium and its protective role in PH remain elusive.Objectives: We investigated the role of AMPK phosphorylation of ACE2 Ser680 in ACE2 stability and deciphered the functional consequences of this post-translational modification of ACE2 in endothelial homeostasis and PH.Methods: Bioinformatics prediction, kinase assay, and antibody against phospho-ACE2 Ser680 (p-ACE2 S680) were used to investigate AMPK phosphorylation of ACE2 Ser680 in endothelial cells. Using CRISPR-Cas9 genomic editing, we created gain-of-function ACE2 S680D knock-in and loss-of-function ACE2 knockout (ACE2-/-) mouse lines to address the involvement of p-ACE2 S680 and ACE2 in PH. The AMPK-p-ACE2 S680 axis was also validated in lung tissue from humans with idiopathic pulmonary arterial hypertension.Measurements and Main Results: Phosphorylation of ACE2 by AMPK enhanced the stability of ACE2, which increased Ang (angiotensin) 1-7 and endothelial nitric oxide synthase-derived NO bioavailability. ACE2 S680D knock-in mice were resistant to PH as compared with wild-type littermates. In contrast, ACE2-knockout mice exacerbated PH, a similar phenotype found in mice with endothelial cell-specific deletion of AMPKα2. Consistently, the concentrations of phosphorylated AMPK, p-ACE2 S680, and ACE2 were decreased in human lungs with idiopathic pulmonary arterial hypertension.Conclusions: Impaired phosphorylation of ACE2 Ser680 by AMPK in pulmonary endothelium leads to a labile ACE2 and hence is associated with the pathogenesis of PH. Thus, AMPK regulation of the vasoprotective ACE2 is a potential target for PH treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • A method using nanoslit-grating structures was proposed to measure the propagation length of SPPs. • A model for performing quantitative measurements was established. • The standard deviation of the proposed method can be as small as 2.33% of its mean value. • The measurement error of the proposed method in measuring the intensity ratio can be smaller than 2% of its theoretical value. The propagation attenuation of surface plasmon polaritons (SPPs) has an important impact on the performance of plasmonic devices, so measuring their propagation length is important for designing plasmonic devices. Here we propose a method using a single nanoslit surrounded on both sides by surface gratings to measure the propagation length of SPPs. In this method, the propagation length of SPPs is obtained by using a narrow-area statistical averaging method to process the data of the intensity ratio of two diffracted light waves, which are converted from two SPPs that have the same initial intensity but travel different distances in opposite directions in a narrow area of a surface of a metal film. We demonstrate experimentally that at the illumination wavelength of 632.8 nm, the mean value of the propagation length of SPPs propagating at the interface between the air and a gold film with a thickness of about 360 nm measured using the proposed method is 9.88 μm, with a standard deviation of 0.23 μm (i.e., 2.33 % of the mean value). In addition, we demonstrate experimentally that the measurement error of the proposed method in measuring the intensity ratio of the two diffracted light waves, which is the dominant error of the proposed method in measuring the propagation length of SPPs, can be smaller than 2 % of its theoretical value. [ABSTRACT FROM AUTHOR]

Abstract: Inverse polarization transmission of light, with the TE transmittance η TE largely exceeding the TM transmittance η TM, through subwavelength metallic gratings at certain wavelength in deep ultraviolet band is theoretically investigated. By using the Fourier modal method and the planar waveguide theory, we show that the light transmission involves both the surface plasmon and the low-loss waveguide modes. Strong coupling of the incident wave to surface plasmon polariton results in the minimum in TM transmittance, whereas the coupling to the low-loss mode leads to the TE transmittance maximum. The established physical mechanism is sufficient to explain the inverse polarizing phenomenon observed in aluminum grating at the wavelength of 193nm, which may lead to important applications such as effective and compact polarizer used in DUV lithography. [Copyright &y& Elsevier]

Achieving a large enhancement of local electromagnetic fields in the ultraviolet waveband is desirable for some applications such as surface-enhanced Raman scattering and surface-enhanced fluorescence. In addition, it is more significant for some applications such as plasmon-enhanced harmonic generation to enhance the intensity of local electromagnetic fields and increase their decay time at the same time. In this paper, using the finite-difference time-domain method, we numerically demonstrate that using the linearly polarized light with a wavelength of 325 nm as the illumination light, an isolated triangular Al-SiO 2 -Al hybrid nanoplate with optimized geometric parameters can produce a local electric field enhanced by a factor of about 108 at one of its top apexes, and produce two local electric fields enhanced by a factor of about 150 at two transverse dielectric/metal interfaces of one of its longitudinal side edges. Moreover, we also numerically demonstrate that the decay time of enhanced local electric fields produced by the isolated triangular Al-SiO 2 -Al hybrid nanoplate is about 1.6 times as large as that of enhanced local electric fields produced by an isolated triangular Al nanoplate. These unique properties of the isolated triangular Al-SiO 2 -Al hybrid nanoplate arise because of both the transverse coupling and the longitudinal coupling of localized surface plasmon polaritons in this structure. Our findings make triangular Al-SiO 2 -Al hybrid nanoplates very promising for application in many fields such as surface-enhanced Raman scattering and plasmon-enhanced harmonic generation., (© 2021 IOP Publishing Ltd.)

Proprotein convertase subtilisin/kexin type 9 (PCSK9) affects cholesterol homeostasis by targeting hepatic LDL receptor (LDLR) for lysosomal degradation. Clinically, PCSK9 inhibitors effectively reduce LDL-cholesterol (LDL-C) levels and the incidence of cardiovascular events. Because microRNAs (miRs) are integral regulators of cholesterol homeostasis, we investigated the involvement of miR-483 in regulating LDL-C metabolism. Using in silico analysis, we predicted that miR-483-5p targets the 3'-UTR of PCSK9 mRNA. In HepG2 cells, miR-483-5p targeted the PCSK9 3'-UTR, leading to decreased PCSK9 protein and mRNA expression, increased LDLR expression, and enhanced LDL-C uptake. In hyperlipidemic mice and humans, serum levels of total cholesterol and LDL-C were inversely correlated with miR-483-5p levels. In mice, hepatic miR-483 overexpression increased LDLR levels by targeting Pcsk9, with a significant reduction in plasma total cholesterol and LDL-C levels. Mechanistically, the cholesterol-lowering effect of miR-483-5p was significant in mice receiving AAV8 PCSK9-3'-UTR but not Ldlr-knockout mice or mice receiving AAV8 PCSK9-3'-UTR (ΔBS) with the miR-483-5p targeting site deleted. Thus, exogenously administered miR-483 or similarly optimized compounds have potential to ameliorate hypercholesterolemia.

The local field enhancement in plasmonic nanostructures is vital for surface enhanced Raman scattering (SERS). However, it remains a challenge to achieve a large local field enhancement at an illumination wavelength in the green waveband. Here we report on an ultra-large local field enhancement effect of isolated thick triangular silver nanoplates (ITTSNPs) on a silicon substrate at an illumination wavelength in the green waveband. We show that when the thickness of the ITTSNP is larger than a critical thickness depending on the illumination wavelength, a large local field enhancement with an enhancement factor (EF) greater than 350 can be achieved at an illumination wavelength in the green waveband, which is due to the excitation of strong localized surface plasmon polaritons only at three top apexes of the ITTSNP. Furthermore, we experimentally demonstrate that at an excitation wavelength of 514.5 nm, the average SERS EF of the ITTSNPs can exceed ${{10}^{11}}$10 11 , and the sensitivity for the detection of Rhodamine 6 G molecules can reach ${{10}^{ - 12}}\;{\rm M}$10 -12 M.

A deep ultraviolet plasmonic structure is designed and a surface plasmon interference lithography method using the structure is proposed to generate large-area periodic nanopatterns. By exciting the anti-symmetric coupled surface plasmon polaritons in the structure, ultrahigh resolution periodic patterns can be formed in a photoresist. The resolution of the generated patterns can be tuned by changing the refractive index and thickness of the photoresist. We demonstrate numerically that one-dimensional and two-dimensional patterns with a half-pitch resolution of 14.6 nm can be generated in a 25 nm-thick photoresist by using the structure under 193 nm illumination. Furthermore, the half-pitch resolution of the generated patterns can be down to 13 nm if high refractive index photoresists are used. Our findings open up an avenue to push the half-pitch resolution of photolithography towards 10 nm.

The purpose of this study is to let a plane periodic grating act as an imaging element for general objects. Using the Fresnel approximation and the Kirchhoff diffraction theory, we investigated an object wave diffracted by a grating. We demonstrated that an image of an original virtual object can be produced by the nth-order monochromatic diffracted wave of a grating. The impulse response of this imaging system and some imaging properties of this imaging system were obtained.