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Lee, Gunsup,Cho, SeungChan,Hoang, Phuong Mai,Kim, Dongjun,Lee, Yongjun,Kil, Eui-Joon,Byun, Sung-June,Lee, Taek-Kyun,Kim, Dae-Hyun,Kim, Sunghan,Lee, Sukchan Korean Society for Molecular and Cellular Biology 2015 Molecules and cells Vol.38 No.9
3D8 single chain variable fragment (scFv) is a recombinant monoclonal antibody with nuclease activity that was originally isolated from autoimmune-prone MRL mice. In a previous study, we analyzed the nuclease activity of 3D8 scFv and determined that a HeLa cell line expressing 3D8 scFv conferred resistance to herpes simplex virus type 1 (HSV-1) and pseudorabies virus (PRV). In this study, we demonstrate that 3D8 scFv could be delivered to target tissues and cells where it exerted a therapeutic effect against PRV. PRV was inoculated via intramuscular injection, and 3D8 scFv was injected intraperitoneally. The observed therapeutic effect of 3D8 scFv against PRV was also supported by results from quantitative reverse transcription polymerase chain reaction, southern hybridization, and immunohistochemical assays. Intraperitoneal injection of 5 and $10{\mu}g$ 3D8 scFv resulted in no detectable toxicity. The survival rate in C57BL/6 mice was 9% after intramuscular injection of 10 $LD_{50}$ PRV. In contrast, the 3D8 scFv-injected C57BL/6 mice showed survival rates of 57% ($5{\mu}g$) and 47% ($10{\mu}g$). The results indicate that 3D8 scFv could be utilized as an effective antiviral agent in several animal models.
Cho, Seungchan,Lee, Yeong-Hwan,Ko, Sungmin,Park, Hyeonjae,Lee, Donghyun,Shin, Sangmin,Jo, Ilguk,Kim, Yangdo,Lee, Sang-Bok,Lee, Sang-Kwan Elsevier 2020 JOURNAL OF ALLOYS AND COMPOUNDS Vol.817 No.-
<P><B>Abstract</B></P> <P>High-temperature compressive strengths of titanium carbide (TiC) reinforced stainless steel composites fabricated by liquid pressing infiltration process were investigated at various temperatures. Effect of TiC on compressive strength of SUS431 was found to increase with increasing testing temperature. TiC reinforcement successfully suppressed softening of SUS431 matrix, resulting in about 5 times higher strength than that of SUS431 at 1050 °C. The novel SUS431 composites reinforced with uniformly dispersed, high volume fraction TiC show great promise for applications in high-temperature environments.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fabrication of lightweight, high strength TiC–SUS431 composites using a novel infiltration process. </LI> <LI> Improvements in high-temperature compressive strengths of about 2.6–5.1 times compared to those of the SUS431 alloy. </LI> <LI> TiC cleavage fracture with no interfacial debonding between TiC and the steel matrix. </LI> <LI> Increased ductility of the composite at about 1050 °C. </LI> <LI> 54% higher compressive strength than that of Rene95 superalloy at 1050 °C. </LI> </UL> </P>
용융가압함침공정을 이용한 세라믹 입자 강화 철강복합재료의 제조성 검증
조승찬 ( Seungchan Cho ),이영환 ( Yeong-hwan Lee ),고성민 ( Seongmin Ko ),박현재 ( Hyeon Jae Park ),이동현 ( Donghyun Lee ),신상민 ( Sangmin Shin ),조일국 ( Ilguk Jo ),이상관 ( Sang-kwan Lee ),이상복 ( Sang-bok Lee ) 한국복합재료학회 2018 Composites research Vol.31 No.4
본 연구에서는 용융가압함침 공정을 이용하여 TiC, TiB<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub> 세라믹 입자가 분산된 SUS431 금속복합재료를 제조하고 미세조직을 분석하여 세라믹 입자에 따른 제조성에 대해 검토하였다. 젖음성이 나쁜 Al<sub>2</sub>O<sub>3</sub>의 경우 내부에 결함이 다수 존재함을 알 수 있었으며, TiB<sub>2</sub> 및 TiC 입자 강화 복합재의 경우 상대적으로 결함이 적고 강화재가 균일 분산되었음을 확인하였다. 특히, TiC-SUS431 복합재료의 경우 TiC와 Fe계 기지합금의 우수한 젖음성 및 용융가압함침공정 적용으로 우수한 계면 특성을 가지며 결함이 적고 균일한 미세조직을 가지는 것을 확인하였다. Various ceramic particulate such as TiC, TiB<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub> reinforced SUS431 matrix composites were successfully fabricated by a novel liquid pressing infiltration process. Microstructures of the SUS431 composite were analyzed to determine manufacturability of composites. Al<sub>2</sub>O<sub>3</sub>-SUS431 composite had lots of defects due to poor wettability between the Al<sub>2</sub>O<sub>3</sub> and steel matrix. On the other hand, TiC was uniformly dispersed in the SUS431 matrix than TiB2 and Al<sub>2</sub>O<sub>3</sub> due to good wettability and interfacial properties.
A Ka-Band Phase-Compensated Variable-Gain CMOS Low-Noise Amplifier
Lee, Seungchan,Park, Jinseok,Hong, Songcheol THE INSTITUTE OF ELECTRICAL ENGINEERS 2019 IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS Vol.29 No.2
<P>A variable-gain low-noise amplifier implemented in a 65-nm CMOS process for a beamforming front-end chip is presented, of which the phase remains constant during gain variations. The phase compensation characteristic is achieved by introducing a shunt PMOS and a parallel resistor at the differential outputs of common-gate (CG) transistors. This allows the gain to be controlled without phase variation by adjustment of the combined gate voltage of the CG transistor and the shunt PMOS at the same time. The proposed device shows a gain of 20.8 dB and a noise figure of 3.71 dB at 31 GHz. It shows a root-mean-square phase error of less than 3° over the gain control range of 10.6 dB at 30–34.5 GHz.</P>
Lee, Gunsup,Yu, Jaelim,Cho, Seungchan,Byun, Sung-June,Kim, Dae Hyun,Lee, Taek-Kyun,Kwon, Myung-Hee,Lee, Sukchan Public Library of Science 2014 PLoS pathogens Vol.10 No.6
<▼1><P>Viral protein neutralizing antibodies have been developed but they are limited only to the targeted virus and are often susceptible to antigenic drift. Here, we present an alternative strategy for creating virus-resistant cells and animals by ectopic expression of a nucleic acid hydrolyzing catalytic 3D8 single chain variable fragment (scFv), which has both DNase and RNase activities. HeLa cells (SCH7072) expressing 3D8 scFv acquired significant resistance to DNA viruses. Virus challenging with Herpes simplex virus (HSV) in 3D8 scFv transgenic cells and fluorescence resonance energy transfer (FRET) assay based on direct DNA cleavage analysis revealed that the induced resistance in HeLa cells was acquired by the nucleic acid hydrolyzing catalytic activity of 3D8 scFv. In addition, pseudorabies virus (PRV) infection in WT C57BL/6 mice was lethal, whereas transgenic mice (STG90) that expressed high levels of 3D8 scFv mRNA in liver, muscle, and brain showed a 56% survival rate 5 days after PRV intramuscular infection. The antiviral effects against DNA viruses conferred by 3D8 scFv expression in HeLa cells as well as an <I>in vivo</I> mouse system can be attributed to the nuclease activity that inhibits viral genome DNA replication in the nucleus and/or viral mRNA translation in the cytoplasm. Our results demonstrate that the nucleic-acid hydrolyzing activity of 3D8 scFv confers viral resistance to DNA viruses <I>in vitro</I> in HeLa cells and in an <I>in vivo</I> mouse system.</P></▼1><▼2><P><B>Author Summary</B></P><P>Most strategies for developing virus-resistant transgenic cells and animals are based on the concept of virus-derived resistance, in which dysfunctional virus-derived products are expressed to interfere with the pathogenic process of the virus in transgenic cells or animals. However, these viral protein targeting approaches are limited because they only target specific viruses and are susceptible to viral mutations. We describe a novel strategy that targets the viral genome itself, rather than viral gene products, to generate virus-resistant transgenic cells and animals. We functionally expressed 3D8 scFv which has both DNase and RNase activities, in HeLa cells and transgenic mice. We found that the transgenic cells and mice acquired complete resistance to two DNA viruses (HSV and PRV) without accumulating the virus, and showed delayed onset of disease symptoms. The antiviral effects against DNA viruses demonstrated in this study were caused by (1) DNase activity of 3D8 scFv in the nucleus, which inhibited DNA replication or RNA transcription and (2) 3D8 scFv RNase activity in the cytoplasm, which blocked protein translation. This strategy may facilitate control of a broad spectrum of viruses, including viruses uncharacterized at the molecular level, regardless of their genome type or variations in gene products.</P></▼2>
Dry Electrode-Based Fully Isolated EEG/fNIRS Hybrid Brain-Monitoring System
Lee, Seungchan,Shin, Younghak,Kumar, Anil,Kim, Minhee,Lee, Heung-No IEEE 2019 IEEE Transactions on Biomedical Engineering Vol.66 No.4
<P>A portable hybrid brain monitoring system is proposed to perform simultaneous 16-channel electroencephalogram (EEG) and 8-channel functional near-infrared spectroscopy (fNIRS) measurements. Architecture-optimized analog frontend integrated circuits (Texas Instruments ADS1299 and ADS8688A) were used to simultaneously achieve 24-bit EEG resolution and reliable latency-less (<;0.85 μs) bio-optical measurements. Suppression of the noise and crosstalk generated by the digital circuit components and flashing NIR light sources was maximized through linear regulator-based fully isolated circuit design. Gel-less EEG measurements were enabled by using spring-loaded dry electrodes. Several evaluations were carried out by conducting an EEG phantom test and an arterial occlusion experiment. An alpha rhythm detection test (eye-closing task) and a mental arithmetic experiment (cumulative subtraction task) were conducted to determine whether the system is applicable to human subject studies. The evaluation results show that the proposed system is sufficiently capable of detecting microvoltage EEG signals and hemodynamic responses. The results of the studies on human subjects enabled us to verify that the proposed system is able to detect task-related EEG spectral features such as eye-closed event-related synchronization and mental-arithmetic event-related desynchronization in the alpha and beta rhythm ranges. An analysis of the fNIRS measurements with an arithmetic operation task also revealed a decreasing trend in oxyhemoglobin concentration.</P>
이종 무선망 환경에서의 성능향상을 위한 수직적 핸드오프 알고리즘
이승찬 ( Seungchan Lee ),서성훈 ( Sunghoon Seo ),송주석 ( Jooseok Song ) 한국정보처리학회 2006 한국정보처리학회 학술대회논문집 Vol.13 No.1
차세대의 무선 네트워크 기술은 기존의 망을 통합하고 IP화 하는 방향으로 발전중이며, WWAN과 WLAN의 통합망에 관한 연구가 활발히 진행 중이다. 본 연구는 최근 상용화 서비스가 이루어지고 있는 WDMB 기술을 WWAN, WLAN과 강결합(Tight Coupling) 방식으로 통합한 네트워크 환경을 제안한다. 본 연구에서 제안하는 수직적 핸드오프(Vertical Handoff) 기법은 WLAN 인터페이스를 필요한 상황에만 구동하여 에너지 소모율을 낮춘다. 또한 WDMB 인터페이스를 상시 구동하여 데이터 트래픽이 발생할 때에 곧바로 WDMB 인터페이스를 통해 데이터 전송을 시작하여 전송률을 높인다. 또한 성능평가를 통하여 단말에 장착된 모든 인터페이스를 구동하는 방식과 비교하여 에너지 소모율이 경감되었으며, 단말에 장착된 한 가지 인터페이스만을 구동하는 방식과의 비교를 통해 데이터 전송률이 크게 향상되었음을 보인다.