Technological process optimization and measurement of image quality of the electrically bifocal metalens.

This Letter describes the design procedure and process optimization of the electrically bifocal metalens. In our design, horizontal and vertical polarization is manipulated by applying a suitable voltage to a twisted nematic liquid crystal (TN-LC) cell. Each nanostructure is designed to be a rectangular prism, making different polarizations of light experience various phase delays, thus causing bi-focus. We selected lithographical methods to fabricate our metalens because of the minimum physical size, which can be as small as 50 nm, and the maximum aspect ratio, which is as high as 15. Furthermore, to increase the tolerance and make the sidewall vertical and smooth, we coated different characteristics of photoresist sensitivity to the upper and lower layers. After the development, the mushroom-type photoresist makes Ni easier to strip while in the lift-off process, thus increasing the quality of the whole metalens. Our experiment shows that the focal lengths and focusing efficiencies corresponding to the two polarizations are similar to the simulation results. The proposed electrically modulated bifocal metalens can be utilized in different applications and combined with other optical components.

Time-Effective Simulation Methodology for Broadband Achromatic Metalens Using Deep Neural Networks.

Metasurface has demonstrated potential and novel optical properties in previous research. The prevailing method of designing a macroscale metasurface is based on the local periodic approximation. Such a method relies on the pre-calculated data library, including phase delay and transmittance of the nanostructure, which is rigorously calculated by the electromagnetic simulation. However, it is usually time-consuming to design a complex metasurface such as broadband achromatic metalens due the required huge data library. This paper combined different numbers of nanofins and used deep neural networks to train our data library, and the well-trained model predicted approximately ten times more data points, which show a higher transmission for designing a broadband achromatic metalens. The results showed that the focusing efficiency of designed metalens using the augmented library is up to 45%, which is higher than that using the original library over the visible spectrum. We demonstrated that the proposed method is time-effective and accurate enough to design complex electromagnetic problems.

Ultrawide-angle and high-efficiency metalens in hexagonal arrangement.

Wide-angle optical systems play a vital role in imaging applications and have been researched for many years. In traditional lenses, attaining a wide field of view (FOV) by using a single optical component is difficult because these lenses have crucial aberrations. In this study, we developed a wide-angle metalens with a numerical aperture of 0.25 that provided a diffraction-limited FOV of over 170° for a wavelength of 532 nm without the need for image stitching or multiple lenses. The designed wide-angle metalens is free of aberration and polarization, and its full width of half maximum is close to the diffraction limit at all angles. Moreover, the metalens which is designed through a hexagonal arrangement exhibits higher focusing efficiency at all angles than most-seen square arrangement. The focusing efficiencies are as high as 82% at a normal incident and 45% at an incident of 85°. Compared with traditional optical components, the proposed metalens exhibits higher FOV and provides a more satisfactory image quality because of aberration correction. Because of the advantages of the proposed metalens, which are difficult to achieve for a traditional single lens, it has the potential to be applied in camera systems and virtual and augmented reality.

Electrically modulated varifocal metalens combined with twisted nematic liquid crystals.

Focus-tunable lenses are indispensable to optical systems. This paper proposes an electrically modulated varifocal metalens combined with twisted nematic liquid crystals. In our design, a metalens is employed to focus on different points depending on the polarization state of incident light. We demonstrated that the varifocal metalens has a sub-millisecond response time. Furthermore, the numerical aperture of both the first and second focal points can be customized to achieve a wide range of 0.2-0.7. Moreover, the full width at half maximum approached the diffraction limit at multiple focal points. Because of the advantages of our proposed electrically modulated metalens, it has the potential for application in optical technology and biomedical science, both of which require high image quality and a rapid response time.

[Detecting Down syndrome with a novel dual-color competitive quantitative fluorescent polymerase chain reaction method].

OBJECTIVE: To develop a rapid method for the detection of Down syndrome (DS) using dual-color competitive quantitative fluorescent polymerase chain reaction (DCC-QF-PCR), and to assess its feasibility for the prenatal diagnosis of Down syndrome. METHODS: DNA was extracted from peripheral blood of 30 DS patients and 60 normal men, common primers for DSCR and USC2 genes and respective TaqMan probes were designed and synthesized. The results of DCC-QF-PCR were compared with those of QF-PCR which measured the ratio between DSCR and GAPDH. Forty-six amniotic fluid samples were assayed with DCC-QF-PCR. The results were compared with that of karyotyping. Monoclone fragments for DSCR and USC2 genes were obtained from direct cloning of PCR products. DCC-QF-PCR was carried out using different DNA ratios of DSCR and USC2 as the template. The dosage ratio between DSCR and USC2 was calculated. RESULTS: The gene dosage ratio of the DS patients was 1.41-1.74, which was significantly higher than that of normal men (0.93-1.15). The dosage ratio range of DSCR and GAPDH by QF-PCR was comparatively greater than that of DSCR and USC2. Three samples were diagnosed as DS, which was in good agreement with that of karyotyping analysis. There was no significant difference between the gene dosage ratio from DCC-QF-PCR and that of predetermined (P>0.05). CONCLUSION: DCC-QF-PCR is an accurate, rapid, and low cost method, which only requires tiny amount of sample and therefore has broad application in the genetic and prenatal diagnosis.

PKCdelta mediates up-regulation of NOX1, a catalytic subunit of NADPH oxidase, via transactivation of the EGF receptor: possible involvement of PKCdelta in vascular hypertrophy.

NADPH oxidase is the major source of superoxide production in cardiovascular tissues. We reported previously that PG (prostaglandin) F2alpha caused hypertrophy of vascular smooth muscle cells by induction of NOX1, a catalytic subunit of NADPH oxidase. PGF2alpha-induced NOX1 expression was mediated by transactivation of the EGF (epidermal growth factor) receptor and subsequent activation of ERK (extracellular-signal-regulated kinase) 1/2, PI3K (phosphoinositide 3-kinase) and ATF-1 (activating transcription factor-1), a member of the CREB (cAMP-response-element-binding protein)/ATF family. As the receptor for PGF2alpha is known to activate PKC (protein kinase C), involvement of PKC in up-regulation of NOX1 expression was investigated in A7r5 cells. GF109203x, a non-selective inhibitor of PKC, dose-dependently suppressed the induction of NOX1 mRNA by PGF2alpha. Whereas an inhibitor of the conventional PKC, Gö 6976, and a PKCeta translocation-inhibitor peptide had no effect, an inhibitor of PKCdelta, rottlerin, significantly attenuated the PGF2alpha-induced increase in NOX1 mRNA. Gene silencing of PKCdelta by RNA interference significantly suppressed the PGF2alpha-induced increase in NOX1 mRNA, as well as phosphorylation of the EGF receptor, ERK1/2 and ATF-1. Silencing of the PKCdelta gene also attenuated the PDGF (platelet-derived growth factor)- induced increase in NOX1 mRNA and transactivation of the EGF receptor. Moreover, the augmented synthesis of the protein induced by PGF2alpha or PDGF was abolished by gene silencing of PKCdelta. These results suggest that PKCdelta-mediated transactivation of the EGF receptor is elicited not only by PGF2alpha, but also by PDGF, and that the subsequent activation of ERK1/2 and ATF-1 leads to up-regulation of NOX1 gene expression and ensuing hypertrophy in the vascular cell lineage.