• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.351-351
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• 2011

Graphene has drawn great interests because of its distinctive band structure and physical properties[1]. A few of the practical applications envisioned for graphene include semiconductor applications, optoelectronics (sola cell, touch screens, liquid crystal displays), and graphene based batteries/super-capacitors [2-3]. Recent work has shown that excellent electronic properties are exhibited by large-scale ultrathin graphite films, grown by chemical vapor deposition on a polycrystalline metal and transferred to a device-compatible surface[4]. In this paper, we focussed our scope for the understanding the graphene growth at different conditions, which enables to control the growth towards the application aimed. The graphene was grown using chemical vapor deposition (CVD) with methane and hydrogen gas in vacuum furnace system. The grown graphene was characterized using a scanning electron microscope(SEM) and Raman spectroscopy. We changed the growth temperature from 900 to $1050^{\circ}C$ with various gas flow rate and composition rate. The growth condition for larger domain will be discussed.

• Molecules and Cells
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• 제20권3호
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• pp.452-452
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• 2005

• 한국응용과학기술학회지
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• 제27권4호
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• pp.545-551
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• 2010

Hydrophobically monoendcapped poly(sodium acrylate)s formed hydrophobic microdomains in water. This was concluded on poly(sodium acrylate)s with a linear $C_{12}$-alkyl chain attached specifically at the end of the polymer. There was no well defined CMC (critical micelle concentration), but rather a gradual transition from a micelle free solution to a micelle solution. Steady state fluorescence spectroscopy indicates that the micro domains are rather hydrophobic. At pH 5 in the abscence of salt and at pH 9 in the prescence of 1 M sodium citrate the CAC (critical aggregation concentration) was in the range of 0.1 to 2.4 mM. However at pH 5 there was a linear increase in the transition concentration with a head-group size due to an increase in steric and electrostatic repulsions between polymer main chains. At pH 9 in the abscence of salt the transition concentration was in the range of 1 to 80 mM. For the larger polymers there was a effect which consisted of a concentration gradient of sodium counterion toward the hydrophobic domain. The effect was larger for the larger polymers because of the higher total sodium concentration and the less steep counterion concentration gradient.

• Carbon letters
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• 제18권
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• pp.37-42
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• 2016

Graphene was grown on molybdenum (Mo) foil by a chemical vapor deposition method at different growth temperatures (1000℃, 1100℃, and 1200℃). The properties of graphene were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy, and Raman spectroscopy. The results showed that the quality of the deposited graphene layer was affected by the growth temperature. XRD results showed the presence of a carbide phase on the Mo surface; the presence of carbide was more intense at 1200℃. Additionally, a higher I_2D/I_G ratio (0.418) was observed at 1200℃, which implies that there are fewer graphene layers at this temperature. The lowest I_D/I_G ratio (0.908) for the graphene layers was obtained at 1200℃, suggesting that graphene had fewer defects at this temperature. The size of the graphene domains was also calculated. We found that by increasing the growth temperature, the graphene domain size also increased.

• Journal of Microbiology and Biotechnology
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• 제27권9호
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• pp.1664-1669
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• 2017

Gamma-aminobutyric acid is a precursor of nylon-4, which is a promising heat-resistant biopolymer. GABA can be produced from the decarboxylation of glutamate by glutamate decarboxylase. In this study, a synthetic scaffold complex strategy was employed involving the Neurospora crassa glutamate decarboxylase (GadB) and Escherichia coli GABA antiporter (GadC) to improve GABA production. To construct the complex, the SH3 domain was attached to the N. crassa GadB, and the SH3 ligand was attached to the N-terminus, middle, and C-terminus of E. coli GadC. In the C-terminus model, 5.8 g/l of GABA concentration was obtained from 10 g/l glutamate. When a competing pathway engineered strain was used, the final GABA concentration was further increased to 5.94 g/l, which corresponds to 97.5% of GABA yield. With the introduction of the scaffold complex, the GABA productivity increased by 2.9 folds during the initial culture period.

• Nuclear Engineering and Technology
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• 제55권9호
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• pp.3183-3193
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• 2023

The water radiolysis in-core at light water reactors (LWRs) produces various radicals with other ionic species/molecules and radioactive nitrogen species in the reactor coolant. Nitrogen species can exist in many different chemical forms and recirculate in water and steam, and consequently contribute to what extent the environmental safety at nuclear power plants. Therefore, a clear understanding of formation kinetics and chemical behaviors of nitrogen species under irradiation is crucial for better insight into the characteristics of major radioactive species released to the main steam or relevant coolant systems and eventually development of advanced processes/methodologies to enhance the environmental safety at nuclear power plants. This paper thus focuses on basic principles on electrochemical interaction kinetics of radiolytic molecules and various nitrogen species in high temperature water, fundamental approaches for calculating thermodynamic values to predict their stability and domain in LWRs, and the effect of nitrogen species on crevice chemistry/corrosion and intergranular stress corrosion cracking (IGSCC) susceptibility of structure materials in high temperature water.

• BMB Reports
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• 제42권12호
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• pp.840-845
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• 2009

Mitogen- and stress-activated protein kinase (MSK1) palys a crucial role in the regulation of transcription downstream of extracellular-signal-regulated kinase1/2 (ERK1/2) and mitogen-activated protein kinase p38. MSK1 can be phosphorylated and activated in cells by both ERK1/2 and p38$\alpha$. In this study, Casein Kinase 2 (CK2) was identified as a binding and regulatory partner for MSK1. Using the yeast two-hybrid system, MSK1 was found to interact with the CK2$\beta$ regulatory subunit of CK2. Interactions between MSK1 and the CK2$\alpha$ catalytic subunit and CK2$\beta$ subunit were demonstrated in vitro and in vivo. We further found that CK2$\alpha$ can only interact with the C-terminal kinase domain of MSK1. Using site-directed mutagenesis assay and mass spectrometry, we identified five sites in the MSK1 C-terminus that could be phosphorylated by CK2 in vitro: Ser757, Ser758, Ser759, Ser760 and Thr793. Of these, Ser757, Ser759, Ser760 and Thr793 were previously unknown.

• 대한화학회지
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• 제66권2호
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• pp.107-123
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• 2022

이 연구는 컴퓨터 기반 과학 탐구 프로그램을 활용한 화학 수업의 효과를 알아보기 위한 것이다. 이를 위해 물질의 특성 영역에서 3차시의 컴퓨터 기반 과학 탐구를 중심으로 하는 교수학습 프로그램을 개발하였다. 개발된 프로그램을 서울에 위치한 K 중학교에 투입하여 효과를 검증하였다. 실험집단은 혼합물의 분리와 관련된 3차시의 컴퓨터 기반 과학 탐구 수업이 도입되었으며, 비교집단은 교과서에서 제시한 내용을 교사 중심의 강의법으로 도입하였다. 프로그램의 효과를 검증하기 위하여, 과학 긍정경험과 과학과 핵심역량은 이원공분산분석(2-way ANCOVA)을, 학업성취도는 이원분산분석(2-way ANOVA)을 실시하였다. 연구 결과, 과학 긍정경험, 과학과 핵심역량, 학업성취도에서 모두 두 집단 간 차이가 유의미하였으며(p<.05), 학업성취도에서만 집단^*성별 상호작용 효과가 유의미하였다(p<.05). 이 연구 결과로부터 지속적인 과학 탐구가 가능한 화학 수업 방법으로 컴퓨터 기반 과학 탐구 프로그램의 활용 가능성을 엿볼 수 있었다.

• 한국미생물·생명공학회지
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• 제37권3호
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• pp.248-257
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• 2009

Vibrio harveyi 쿼럼 센싱 (quorum sensing; QS) 신호전달에 대한 저해제들이 주 신호물질인 N-3-hydroxybutanoyl-L-homoserine lactone(3-OH-$C_4$-HSL)의 분자 구조를 변형함에 의해 개발되었다. 일련의 구조 변형체들인 N-(3-hyoxysulfonyl)-L-homoserine lactones(HSHLs)들은 고체상 유기합성법 (solid-phase organic synthesis method)으로 합성되었다. 이 물질들의 생체내 쿼럼 센싱 저해능이 V. harveyi 발광을 이용한 bloassay를 system에 의해 측정되었을 때, 모두 의미있는 저해효과를 보여주었다. 이 물질들과 3-OH-$C_4$-HSL 수용체 단백질인 LuxN 사이의 상호작용을 분석하기 위하여 LuxN의 신호 결합 부위를 다른 acyl-HSL 결합 단백질들과의 유사성에 기초하여 시험적으로 결정하였다. 이 추정 신호결합 부위의 부분적 삼차구조를 ORCHESTRA program을 이용하여 예측하였으며, 이 부위 내에서 3-OH-$C_4$-HSL와 HSHLs의 결합 형태와 에너지를 계산하였다. 이렇게 모델링을 통해 얻어진 결과와 생체 내 bioassay를 통해 얻어진 결과의 비교를 통해, 수용체 단백질과 그 리간드 사이의 상호 작용에 관한 in silica 해석이 특히 단백질의 삼차 구조에 대한 정보가 제한적인 경우에 보다 나은 저해제 개발을 위한 유용한 방법이 될 수 있음을 제안한다.

• Molecules and Cells
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• 제20권1호
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• pp.69-73
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• 2005

The flavonoid, quercetin, is a low molecular weight substance found in apple, tomato and other fruit. Besides its antioxidative effect, quercetin, like other flavonoids, has a wide range of neuropharmacological actions including analgesia, and motility, sleep, anticonvulsant, sedative and anxiolytic effects. In the present study, we investigated its effect on mouse 5-hydroxytryptamine type 3 ($5-HT_{3A}$) receptor channel activity, which is involved in pain transmission, analgesia, vomiting, and mood disorders. The $5-HT_{3A}$ receptor was expressed in Xenopus oocytes, and the current was measured with the two-electrode voltage clamp technique. In oocytes injected with $5-HT_{3A}$ receptor cRNA, quercetin inhibited the 5-HT-induced inward peak current ($I_{5-HT}$) with an $IC_{50}$ of $64.7{\pm}2.2{\mu}M$. Inhibition was competitive and voltage-independent. Point mutations of pre-transmembrane domain 1 (pre-TM1) such as R222T and R222A, but not R222D, R222E and R222K, abolished inhibition, indicating that quercetin interacts with the pre-TM1 of the $5-HT_{3A}$ receptor.