다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Metamaterials, or engineered materials with rationally designed, subwavelength-scale building blocks, allow us to control the behavior of physical fields in optical, microwave, radio, acoustic, heat transfer, and other applications with flexibility and performance that are unattainable with naturally available materials. In turn, metasurfaces-planar, ultrathin metamaterials-extend these capabilities even further. Optical metasurfaces offer the fascinating possibility of controlling light with surface-confined, flat components. In the planar photonics concept, it is the reduced dimensionality of the optical metasurfaces that enables new physics and, therefore, leads to functionalities and applications that are distinctly different from those achievable with bulk, multilayer metamaterials. Here, we review the progress in developing optical metasurfaces that has occurred over the past few years with an eye toward the promising future directions in the field.

/pdf/planar-photonics-with-metasurfaces-1sfd62lis7.pdf

Planar Photonics with Metasurfaces

Subwavelength resolution imaging requires high numerical aperture (NA) lenses, which are bulky and expensive. Metasurfaces allow the miniaturization of conventional refractive optics into planar structures. We show that high-aspect-ratio titanium dioxide metasurfaces can be fabricated and designed as metalenses with NA = 0.8. Diffraction-limited focusing is demonstrated at wavelengths of 405, 532, and 660 nm with corresponding efficiencies of 86, 73, and 66%. The metalenses can resolve nanoscale features separated by subwavelength distances and provide magnification as high as 170×, with image qualities comparable to a state-of-the-art commercial objective. Our results firmly establish that metalenses can have widespread applications in laser-based microscopy, imaging, and spectroscopy.

Metalenses at visible wavelengths: Diffraction-limited focusing and subwavelength resolution imaging.

Realizing Spin-Conserved and Spin-Encrypted Hologram using Multipolar-modulated Meta-platform

The surface passivation of a CMOS image sensor (CIS) is highly beneficial for the overall improvement of a device performance. We employed the thermal atomic layer deposition (T-ALD) and plasma enhanced (PE-ALD) techniques for the deposition of 20 nm HfO2 as well as stacked with 3 and 5 nm Al2O3 thin films. The HfO2/Si and Al2O3/HfO2/Si metal-oxide-semiconductor structures were used to analyze the fixed charge density (<inline-formula> <tex-math notation="LaTeX">$\text{Q}_{\mathrm {f}}$ </tex-math></inline-formula>) and interface trap density (<inline-formula> <tex-math notation="LaTeX">$\text{D}_{\mathrm {it}}$ </tex-math></inline-formula>). The as-synthesized samples show high <inline-formula> <tex-math notation="LaTeX">$\text{D}_{\mathrm {it}}$ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">$\text{Q}_{\mathrm {f}}$ </tex-math></inline-formula> values (1012 cm−2eV−1) and a minority carrier lifetime of 15–300 <inline-formula> <tex-math notation="LaTeX">$\mu \text{s}$ </tex-math></inline-formula>. The finite-difference time-domain simulation of high-k dielectrics confirmed that the Al2O3 (top)/HfO2 stacked structures expected higher quantum efficiency for CIS application. The effect of vacuum annealing (VA) and forming gas annealing (FGA) treatments succeeded with the decomposition of the <inline-formula> <tex-math notation="LaTeX">$\text{D}_{\mathrm {it}}$ </tex-math></inline-formula> and increase in carrier lifetime. The H2 ambient FGA samples showed a remarkable decrease in the <inline-formula> <tex-math notation="LaTeX">$\text{D}_{\mathrm {it}}$ </tex-math></inline-formula> values. To improve the overall performance of the device after passivation, we employed an Al2O3/HfO2 bilayer structure, which showed a low <inline-formula> <tex-math notation="LaTeX">$\text{D}_{\mathrm {it}}$ </tex-math></inline-formula> of 1011 cm−2eV−1 and a minority carrier lifetime of <inline-formula> <tex-math notation="LaTeX">$\sim 3$ </tex-math></inline-formula>,700 <inline-formula> <tex-math notation="LaTeX">$\mu \text{s}$ </tex-math></inline-formula> after 400 °C and 30 min FGA. We believe that this surface passivation strategy will pave way for future CIS technology regarding the development of lower defective surface and superior performance.

https://ieeexplore.ieee.org/ielx7/6287639/6514899/09797717.pdf

Effect of ALD Processes on Physical and Electrical Properties of HfO2 Dielectrics for the Surface Passivation of a CMOS Image Sensor Application

The applicability of piezoelectric energy harvesting is increasingly investigated in the field of renewable energy. In improving harvester efficiency, manipulating elastic waves through a geometric configuration as well as upgrading harvester elements is important. Periodic structures, such as phononic crystals and metamaterials, are extensively employed to control elastic waves and enhance harvesting performance, particularly in terms of wave localization and focusing. In this study, we propose a double-focusing flexural energy harvesting platform consisting of a gradient-index lens and elastic Bragg mirror. Based on the design process, the frequency and time response of the harvesting platform are analyzed. The results indicate that the output voltage and power calculated at 1800 Ω are 7.9 and 62 times higher than those observed in the bare plate, respectively. Even when compared to the existing gradient-index system, they are 1.5 and 2.3 times higher, respectively. These findings can facilitate the usage of periodic structures as geometric stimuli to significantly enhance harvesting performance.

https://www.mdpi.com/2079-4991/12/6/1019/pdf?version=1647849765

Double-Focusing Gradient-Index Lens with Elastic Bragg Mirror for Highly Efficient Energy Harvesting

Abstract. The explosion in the amount of information that is being processed is prompting the need for new computing systems beyond existing electronic computers. Photonic computing is emerging as an attractive alternative due to performing calculations at the speed of light, the change for massive parallelism, and also extremely low energy consumption. We review the physical implementation of basic optical calculations, such as differentiation and integration, using metamaterials, and introduce the realization of all-optical artificial neural networks. We start with concise introductions of the mathematical principles behind such optical computation methods and present the advantages, current problems that need to be overcome, and the potential future directions in the field. We expect that our review will be useful for both novice and experienced researchers in the field of all-optical computing platforms using metamaterials.

https://www.spiedigitallibrary.org/journals/advanced-photonics/volume-4/issue-6/064002/Computation-at-the-speed-of-light--metamaterials-for-all/10.1117/1.AP.4.6.064002.pdf

Computation at the speed of light: metamaterials for all-optical calculations and neural networks

The high refractive indexes and low optical losses of dielectrics are preferred for designing highly efficient metasurfaces with unprecedented wavefront control such as near-unity numerical aperture metalenses and wide-angle beam spreading. Regardless of such intuitive material selections, the correlation between metasurface performance and material properties has not been clearly defined. Notwithstanding the unclear correlation, the intensity ratio of manipulated light to input beam, often called the efficiency, is an important factor for constructing various photonic applications from augmented reality to sensors. In this context, the efficiency records of the previous metasurfaces should be classified with materials aspects to understand current limitations on their efficiencies. This perspective organizes the efficiency records of metasurfaces depending on optical materials, introducing a way to engineer the optical properties of various dielectric materials to improve metasurface efficiencies. Furthermore, this perspective covers the candidates for nonlinear optical materials that can potentially be used for efficient frequency conversion. 

Junsuk Rho

Papers

Realizing Spin-Conserved and Spin-Encrypted Hologram using Multipolar-modulated Meta-platform

Effect of ALD Processes on Physical and Electrical Properties of HfO2 Dielectrics for the Surface Passivation of a CMOS Image Sensor Application

Double-Focusing Gradient-Index Lens with Elastic Bragg Mirror for Highly Efficient Energy Harvesting

Computation at the speed of light: metamaterials for all-optical calculations and neural networks

Revisiting Optical Material Platforms for Efficient Linear and Nonlinear Dielectric Metasurfaces in the Ultraviolet, Visible, and Infrared