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Recent progress in development and applications of second near? infrared (NIR-II) nanoprobes
Jongyoon Shinn,Sunyoung Lee,Hyon Kyong Lee,Jaeeun Ahn,Seon Ah Lee,Seonju Lee,이용현 대한약학회 2021 Archives of Pharmacal Research Vol.44 No.2
Optical probes for near-infrared (NIR) lighthave clear advantages over UV/VIS-based optical probes,such as their low levels of interfering auto-fl uorescenceand high tissue penetration. The second NIR (NIR-II) window(1000−1350 nm) off ers better light penetration, lowerbackground signal, higher safety limit, and higher maximumpermitted exposure than the fi rst NIR (NIR-I) window(650−950 nm). Therefore, NIR-II laser–based photoacoustic(PA) and fl uorescence (FL) imaging can off er higher sensitivityand penetration depth than was previously available,and deeper lesions can be treated in vivo by photothermaltherapy (PTT) and photodynamic therapy (PDT) with anNIR-II laser than with an NIR-I laser. Advances in creationof novel nanomaterials have increased options for improvinglight-induced bioimaging and treatment. Nanotechnologycan provide advantages such as good disease targetingability and relatively long circulation times to supplementthe advantages of optical technologies. In this review, wepresent recent progress in development and applications ofNIR-II light–based nanoplatforms for FL, PA, image-guidedsurgery, PDT, and PTT. We also discuss recent advances insmart NIR-II nanoprobes that can respond to stimuli in thetumor microenvironment and infl amed sites. Finally, we considerthe challenges involved in using NIR-II nanomedicinefor eff ective diagnosis and treatment.
Lee, Hyojin,Kim, Hyungmin,Kim, Jongyoon,Lee, Ji-Hoon IOP 2016 Journal of Physics. D, Applied Physics Vol.49 No.7
<P>We experimentally measured the splay (<I>e</I> <SUB>s</SUB>) and the bend flexoelectric coefficients (<I>e</I> <SUB>b</SUB>) of liquid crystal (LC) mixtures with negative dielectric anisotropy and investigated their effect on the image flicker of the LC mixtures driven with a low frequency electric field. Using the experimentally measured <I>e</I> <SUB>s</SUB> and <I>e</I> <SUB>b</SUB>, we simulated the transmittance (TR) response with the continuum model. First, we confirmed that the TR simulation results were approximated to the experimental data with only small variation. Second, we varied the simulation parameters of <I>e</I> <SUB>s</SUB> <I>, e</I> <SUB>b</SUB>, the separation (<I>S</I>), and the width (<I>W</I>) of the interdigitated electrodes and tried to find the optimum condition showing the least image flicker. Given <I>W</I> = 3.0 <I>μ</I>m and <I>e</I> <SUB>b</SUB> = 5.7 pC m<SUP>−1</SUP>, it was found that the image flicker could be minimized when the <I>e</I> <SUB>s</SUB> <I>/e</I> <SUB>b</SUB> value was about 2.4 and the <I>S</I>/<I>W</I> ratio was about 1.5. Because the <I>e</I> <SUB>s</SUB> <I>/e</I> <SUB>b</SUB> value of the rod-like LC material is generally less than 1, it is desirable to design an interdigitated electrode structure to minimize the image flicker effect.</P>
Transfer Characteristics Comparison of HfO₂ Al₂O₃ Deposited InGaZnO Thin Film Transistors
Jongyoon Lee,Byoundeog Choi 한국진공학회 2021 한국진공학회 학술발표회초록집 Vol.2021 No.2
Transfer characteristics of indium-gallium-zinc-oxide thin film transistors (IGZO TFTs) using HfO<sub>2</sub> and Al<sub>2</sub>O<sub>3</sub> as gate dielectrics were identified. We confirmed that the subthreshold swing of the TFTs with Al<sub>2</sub>O<sub>3</sub> (0.68 V/decade) is lower than that of TFT with HfO<sub>2</sub> (1.27 V/decade). Also, TFT with Al<sub>2</sub>O<sub>3</sub> has higher saturation mobility (µsat) (7.56 cm<sup>2</sup>/Vs) than TFT with Hf02 (2.12 cm<sup>2</sup>/Vs) even though HfO<sub>2</sub> has higher dielectric constant. Because Al<sub>2</sub>O<sub>3</sub> IGZO has lower Nr (5.58 x 10¹² cm<sup>-2</sup>) than that of HfO<sub>2</sub>devices (1.8 x 10 cm<sup>-2</sup>) the carrier scattering in the IGZO channel can be reduced.
Optimization of the display viewing angle for automotive application
Kim Jongyoon,Lee Dae-Heung,Lee Joun-Ho,Lee Ji-Hoon 한국정보디스플레이학회 2022 Journal of information display Vol.23 No.1
We studied the optimization of viewing angle properties of the in-plane switching (IPS) liquid crystal display (LCD) for automotive applications. We studied the optical properties inside the automotive viewing zone (AVZ) with narrow vertical and wide horizontal viewing angle range defined in German OEM specifications. The average dark state transmittance (TRd) and contrast ratio (CR) of the IPS-LCD compensated with a+A and a+C plate could be enhanced by 2.5% and 0.8%, respectively, in the AVZ by inserting an additional -C plate. The uniformity of TRd and CR in the AVZ zone also improved by 39.3% and 24.9%, respectively. Enhancement of optical properties by the additional -C plate was also observed in the IPS-LCD compensated with a Z plate. On the other hand, the optical properties of the IPS-LCD compensated with a -B and a+C plate were optimal when Rth of the existing+C plate is optimized for automotive displays.
Smart pH-responsive nanomedicines for disease therapy
Shinn Jongyoon,Kwon Nuri,Lee Seon Ah,Lee Yonghyun 한국약제학회 2022 Journal of Pharmaceutical Investigation Vol.52 No.4
Background Currently nanomedicines are the focus of attention from researchers and clinicians because of the successes of lipid-nanoparticles-based COVID-19 vaccines. Nanoparticles improve existing treatments by providing a number of advantages including protection of cargo molecules from external stresses, delivery of drugs to target tissues, and sustained drug release. To prevent premature release-related side effects, stable drug loading in nanoformulations is required, but the increased stability of the formulation could also lead to a poor drug-release profile at the target sites. Thus, researchers have exploited differences in a range of properties (e.g., enzyme levels, pH, levels of reduced glutathione, and reactive oxygen species) between non-target and target sites for site-specific release of drugs. Among these environmental stimuli, pH gradients have been widely used to design novel, responsive nanoparticles. Area covered In this review, we assess drug delivery based on pH-responsive nanoparticles at the levels of tissues (tumor microenvironment, pH ~ 6.5) and of intracellular compartments (endosome and lysosome, pH 4.5–6.5). Upon exposure to these pH stimuli, pH-responsive nanoparticles respond with physicochemical changes to their material structure and surface characteristics. These changes include swelling, dissociation, or surface charge switching, in a manner that favors drug release at the target site (the tumor microenvironment region and the cytosol followed by endosomal escape) rather than the surrounding tissues. Expert opinion Lastly, we consider the challenges involved in the development of pH-responsive nanomedicines.
Design and development of the helicity injection system in Versatile Experiment Spherical Torus
Park, JongYoon,An, Younghwa,Jung, Bongki,Lee, Jeongwon,Lee, HyunYoung,Chung, Kyoung-Jae,Na, Yong-Su,Hwang, Y.S. Elsevier 2015 Fusion engineering and design Vol.96 No.-
<P><B>Abstract</B></P> <P>A helicity injection system for the Versatile Experiment Spherical Torus (VEST) has been successfully developed and commissioned. A high current electron gun utilizing hollow cathode and washer stacks has been designed and constructed with a single pulse power system that can provide voltages for both arc discharge and extraction sequentially. Tests for electron gun operation with the single pulse power system have been conducted under various toroidal and poloidal field strengths. The estimated plasma impedance, depending on the injection magnetic field structure, can be utilized for the optimal gun operation by impedance matching between the pulse power system and plasma. With the charging voltage of 1.2kV, injection current of 0.95kA has been obtained with the injection voltage of 410V for about 5ms. Initial helicity injection experiments have been conducted under various toroidal and poloidal field strengths and a toroidal plasma current of up to 3.8kA is observed with the current multiplication larger than the geometric stacking ratio, confirming the possibility of relaxation into tokamak-like plasma with closed flux formation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A high current electron gun with single pulse power for both arc and extraction is developed. </LI> <LI> The optimal gun operation is confirmed by impedance matching between the PFN and plasma. </LI> <LI> The gun injected currents of 0.95kA with the voltage of ∼410V for 5ms with a 1.2kV PFN. </LI> <LI> The helicity injection system using the gun has been developed and tested successfully in VEST. </LI> <LI> Toroidal currents of up to 3.8kA confirm possible relaxation into tokamak-like plasma. </LI> </UL> </P>