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원조포미바이러스 U5 LTR 말단의 보존적인 잔기의 돌연변이에 대한 인테그라제의 반응성
현우석,이동현,고현탁,신차균,Hyun, U-Sok,Lee, Dong-Hyun,Ko, Hyun-Tak,Shin, Cha-Gyun 대한약학회 2008 약학회지 Vol.52 No.2
The long terminal repeat (LTR) of retroviral DNA genome plays an important role in the integration process by providing substrate recognition site for viral integrase (IN). The dinucleotide CA near the 3'-end of the LTR termini is completely conserved among retoviruses. In order to study specificity of interaction between prototype foamy virus (PFV) IN and its U5 LTR DNA, the effect of mutagenesis of the CA sequence was investigated by studying reactivity of PFV IN to the mutant LTR substrates. Replacement of only the C or the A allowed 60 to 100% of the reactivity of the wild type LTR substrate. In addition, replacement of the C and the A showed 50 to 80% of the reactivity of the wild type LTR substrate, indicating that PFV IN has less specificity on the conserved CA sequence when it is compared to the other retroviral INs. Therefore it is suggested that PFV IN is less dependent on the conserved sequence of LTR termini for its enzymatic reaction.
Performance Characterization of Polyaniline Coated Electro-Active Paper Actuator
Hyun-U Ko(고현우),Seong Cheol Mun(문성철),Lindong Zhai(적림동),Ki-Baek Kim(김기백),Jaehwan Kim(김재환) Korean Society for Precision Engineering 2013 한국정밀공학회지 Vol.30 No.6
Bending actuators composed of cellulose with an electrically conducting polymer (CP) are fabricated and their performance is characterized in the air. Two different counter ions, perchlorate and tetrafluoroborate are used as dopant ions in the polyaniline CP processing. CPcellulose- CP trilayer and CP-cellulose bilayer samples are fabricated with different dopant ions, and their actuation performance is evaluated in terms of tip displacement, blocked force and electrical power consumption along with the humidity level and actuation frequency. The trilayer samples substantially enhanced the tip displacement compared to the bilayer ones. The actuation performance of the trilayer actuator is three times better than that of original cellulose electroactive paper (EAPap) actuator. The displacement and blocked force of CP-EAPap actuators are dependent on the humidity and frequency.
Ko, Hyun-U,Kim, Hyun Chan,Kim, Jung Woong,Zhai, Lindong,Jayaramudu, Tippabattini,Kim, Jaehwan Institute of Physics Publishing 2017 Smart materials & structures Vol.26 No.8
<P>This paper reports cellulose nanocrystal (CNC) based transparent and electroactive polyurethane (CPPU), suitable for actively tunable optical lens. CNC is used for high dielectric filler to improve electromechanical behavior of CPPU. For high transparency and homogeneous distribution of CNC in polyurethane, CNC-poly[di(ethylene glycol) adipate] is used to play a role of polyol and isocyanate salt. The fabricated CPPU exhibits high transparency (>90%) and 10% of electromechanical strain under 3 V <I>μ</I>m<SUP>−1</SUP> electric field. Mechanical, dielectric properties as well as physical and chemical characteristics are investigated to prove the electromechanical behavior of CPPU.</P>
Ko, Young Ok,Jeon, Hyun Ji,Jung, Da Jung,Kim, U Bin,Lee, Sang-gi American Chemical Society 2016 ORGANIC LETTERS Vol.18 No.24
<P>A novel, one-pot route for the synthesis of nonaromatic ring fused 1,4-oxazepines and 1,4-oxazines has been developed. The reaction features a sequential rhodium(II)-catalyzed reaction of N-sulfonyl-1,2,3-triazoles with glycidols, followed by a regioselective Lewis acid Mg((OBu)-Bu-t)(2)-catalyzed intramolecular ring-opening reaction. It has been found that the regioselectivity in the epoxide ring-opening was largely determined by the substituents on the glycidols. Thus, substituted glycidols (R-2 not equal H) afforded seven-membered oxazepine derivatives selectively, while unsubstituted glycidols (R-2 = H) afforded six-membered oxazine derivatives. Plausible reaction pathways are elucidated and supported by experiments with several glycidols bearing different substituents around the epoxide functionality.</P>
Fabrication and Characterization of Array Tactile Actuator Based on Cellulose Acetate
Hyun-Chan Kim(김현찬),Sungryl Yun(윤성률),Hyun-U Ko(고현우),Jaehwan Kim(김재환) Korean Society for Precision Engineering 2015 한국정밀공학회지 Vol.32 No.8
This paper reports the enhanced fabrication and characterization of a 3 × 3 array tactile actuator composed of cellulose acetate. The array tactile actuator, with dimensions of 15 × 15 × 1 ㎣, consists of 9 pillar-supported cells made from a cellulose-acetate molding. The fabrication process and performance test along with the results for the suggested actuator are explained. To improve the cell-array fabrication, a laser cut was adopted after the molding process. The displacement of the unit cell increased the input voltage and frequency. Various top masses are added onto the actuator to mimic the touch force, and the acceleration of the actuator is measured under actuation. When 2 kV is applied to the actuator, the maximum acceleration is 0.64 g, which is above the vibrotactile threshold. The actuation mechanism is associated with the electrostatic force between the top and bottom electrodes.
라카디브 해역 몰디브 자생 해조류 Padina boryana 추출물의 항산화 효능 평가
김현수 ( Hyun-soo Kim ),( Lei Wang ),( Thilina U. Jayawardena ),이정민 ( Jeong Min Lee ),임미진 ( Mi-jin Yim ),고석천 ( Seok-chun Ko ),이효근 ( Hyo-geun Lee ),제준건 ( Jun-geon Je ),전유진 ( You-jin Jeon ),이대성 ( Dae-sung 한국수산과학회(구 한국수산학회) 2021 한국수산과학회지 Vol.54 No.2
Global warming has affected the distribution of organisms for decades and has displayed rapid ascent recently. Research into the effects on tropical organisms are vital. Padina boryana is a resourceful marine microalgae in the Maldives Sea in the Laccadive region. A 70% ethanol extraction (PBE) of this seaweed was used to investigate its antioxidant potential. Both in vitro and in vivo models were implemented. PBE exhibited protective potential against H2O2 induced apoptosis. ROS levels were suppressed due to PBE. PBE expressed a cytoprotective nature. In vivo experiments involving the zebra fish model conformed its validity. The antioxidant efficacy of PBE was dose dependent. Study outcomes suggest PBE has potential as a novel and valuable marine resource to aid the functional food and cosmeceutical industries.
Kim, Hyun Chan,Mun, Seongcheol,Ko, Hyun-U,Zhai, Lindong,Kafy, Abdullahil,Kim, Jaehwan IOP 2016 Smart materials & structures Vol.25 No.7
<P>The use of renewable materials is essential in future technologies to harmonize with our living environment. Renewable materials can maintain our resources from the environment so as to overcome degradation of natural environmental services and diminished productivity. This paper reviews recent advancement of renewable materials for smart material applications, including wood, cellulose, chitin, lignin, and their sensors, actuators and energy storage applications. To further improve functionality of renewable materials, hybrid composites of inorganic functional materials are introduced by incorporating carbon nanotubes, titanium dioxide and tin oxide conducting polymers and ionic liquids. Since renewable materials have many advantages of biocompatible, sustainable, biodegradable, high mechanical strength and versatile modification behaviors, more research efforts need to be focused on the development of renewable smart materials.</P>