• Bulletin of the Korean Chemical Society
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• 제35권8호
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• pp.2423-2430
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• 2014

Nitrogen-doped short tubular carbons (N-STCs) with big inner diameter have been successfully synthesized via carbonization of polydopamine (PDA) wrapped halloysite nanotubes (HNTs). The obtained N-STCs have average length of $0.3{\mu}m$ with big inner diameter (50 nm), thin wall (2-3 nm) and large surface area ($776m^2g^{-1}$), and show excellent electrochemical properties. As an example in electrochemical applications, N-STCs were used to electrochemically detect hydrogen peroxide ($H_2O_2$) and glucose. The results showed that the N-STCs modified glassy carbon (N-STCs/GC) electrode had much better analytical performance (lower detection limit and wider linear range) compared to the acid-treated carbon nanotubes (AO-CNTs) based GC electrode. The unique structure endows N-STCs the enhanced electrochemical performance and promising applications in electrochemical sensing.

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2178-2182
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• 2011

Recently, the synthesis of ordered macroporous materials has received much attention due to its potential use as photonic band gap materials.$^1$ In this study, we have used the three-dimensional (3D) latex array template impregnated with benzenesulfonic acid (BSA), which is capable of catalyzing the reaction using tetraethyl orthosilicate (TEOS) as a precursor and distilled water. The polystyrene (PS) templates were reacted with TEOS in $scCO_2$ at 40 $^{\circ}C$ and at 80 bar. In the reactor, TEOS was filtrated into the PS particle lattice. After the reaction, porous silica materials were obtained by calcinations of the template. The stability test of the PS template in pure $CO_2$ was conducted before the main experiment. Scanning electron microscopy (SEM) images showed that the reaction in $scCO_2$ takes place only on the particle surface. This new method using $scCO_2$ has advantages over conventional sol-gel processes in its capability to control the fluid properties such as viscosity and interfacial tension. It has been found that the reaction in $scCO_2$ occurs only on the particle surface, making the proposed technique as more rapid and sustainable method of synthesizing inverse opal materials than conventional coating processes in the liquid phase and in the vapor phase.

• Molecules and Cells
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• 제26권1호
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• pp.5-11
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• 2008

Stalled DNA replication forks activate specific DNA repair mechanism called post-replication repair (PRR) pathways that simply bypass DNA damage. The bypassing of DNA damage by PRR prevents prolonged stalling of DNA replication that could result in double strand breaks (DSBs). Proliferating cell nuclear antigen (PCNA) functions to initiate and choose different bypassing pathways of PRR. In yeast, DNA replication forks stalled by DNA damage induces monoubiquitination of PCNA at K164, which is catalyzed by Rad6/Rad18 complex. PCNA monoubiquitination triggers the replacement of replicative polymerase with special translesion synthesis (TLS) polymerases that are able to replicate past DNA lesions. The PCNA interaction motif and/or the ubiquitin binding motif in most TLS polymerases seem to be important for the regulation of TLS. The TLS pathway is usually error-prone because TLS polymerases have low fidelity and no proofreading activity. PCNA can also be further polyubiquitinated by Ubc13/ Mms2/Rad5 complex, which adds an ubiquitin chain onto monoubiquitinated K164 of PCNA. PCNA polyubiquitination directs a different PRR pathway known as error-free damage avoidance, which uses the newly synthesized sister chromatid as a template to bypass DNA damage presumably through template switching mechanism. Mammalian homologues of all of the yeast PRR proteins have been identified, thus PRR is well conserved throughout evolution. Mutations of some PRR genes are associated with a higher risk for cancers in mice and human patients, strongly supporting the importance of PRR as a tumor suppressor pathway.

• 멤브레인
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• 제22권1호
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• pp.35-45
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• 2012

양극산화 알루미나(AAO)막의 나노 사이즈 미세공(세공 크기 20 nm, 10 nm 및 200 nm)을 주형으로 사용하여 전도성 고분자인 폴리피롤, 폴리아닐린 중합체 및 폴리피롤/폴리아닐린 공중합체 나노와이어를 제조하였다. 미세공 주형 내에서 전도성 고분자의 성장은 세공의 벽면을 따라 튜브 형태로서 성장하였으며, 3시간 이후에는 내부가 완전히 채워진 나노와이어가 형성되었다. AAO 막을 수산화나트륨 용액으로 퍼리하여 세공 내에 형성된 전도성 고분자 나노와이어를 회수 하였으며. 회수된 나노와이어�l 직경과 길이는 주형 막의 세공 형상과 일치하였다. 통상의 용액 중합법으로 제조된 전도성 고분자 분말과 비교하여 주형 합성법으로 제조된 전도성 고분자 나노와이어는 결정성과 열적 안정성이 향상되었으며, 전기 저항은 4~60% 감소하였다.

• 한국결정학회지
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• 제16권2호
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• pp.128-137
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• 2005

졸-겔 형판 합성법으로 제조된 페롭스카이트 나노구조의 입자크기에 따른 상전이를 연구하였다. 타탄산납, $PbTiO_{3}$, 화합물의 나노구조는 출발물질인 티타늄 테트라부톡사이드($Ti(OBu)_{4}$)와 아세트산 납($Pb(OAc)_{2}-3H_{2}O$)을 선택된 용매에 녹이고, 산화 알루미늄 형판($AlO_{x}\;template$)을 이용한 졸-겔 합성과정으로 거쳐서 제조하였다. 이 때, 200-nm 직경의 세공을 가진 막($Whatman^{\circledr}\;anodisc\;membranes$)이 형판으로 이용되었다. 선구물질이 코팅된 형판을 공기 중에서 말린 후, $650^{\circ}C$에서 소결하고, 6M-NaOH 용액에서 형판을 제거하였다. $PbTiO_{3}$ 나노구조의 상전이는 DSC, DTA, 비선형 광학적 특성 등을 이용하여 조사하였다.

• Korean Chemical Engineering Research
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• 제56권2호
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• pp.261-268
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• 2018

본 연구에서는 수열합성법과 주형합성법을 이용하여 메조포어를 지닌 $TiO_2$를 합성하였다. 수열합성법을 이용해서 anatase 구조의 메조포러스 $TiO_2$를 합성했다. Rutile 구조의 메조포러스 $TiO_2$를 제조하기 위해서 수열합성법으로 제조된 메조포러스 $TiO_2$를 $300^{\circ}C$부터 $700^{\circ}C$까지 소성시켰더니 $600^{\circ}C$부터 anatase에서 rutile 결정구조로 상전이가 일어났다. 하지만, 메조포어가 붕괴되었다. 메조포어을 지닌 $TiO_2$를 합성하기 위해서 메조포러스 실리카 KIT-6을 주형으로 사용하는 주형합성법을 사용하였다. 먼저 메조포어 내부에 $TiO_2$를 형성시키고 소성온도를 800, $900^{\circ}C$로 높여서 anatase에서 rutile로의 상전이 거동을 조사하였다. 수열합성을 통해 제조된 자유로운 상태의 메조포러스 $TiO_2$의 경우 $600^{\circ}C$에서 anatase에서 rutile로의 상전이가 일어났지만 제한된 공간인 메조포러스 기공 내부에 형성된 $TiO_2$의 경우 $800^{\circ}C$까지 가열하더라도 rutile구조로 상전이가 일어나지 않았고, $900^{\circ}C$로 소성시키자 일부의 anatase가 rutile로의 상전이가 일어나기 시작하였다. 이러한 상전이는 산소 빈자리의 형성에 의해서 일어나야 한다고 알려져 있지만 실리카 기공 내부에 형성된 $TiO_2$는 실리카 기공 표면이 산소 빈자리 형성을 방해해서 상전이가 억제되는 것으로 판단된다. $900^{\circ}C$의 높은 소성온도로 인해서 anatase와 rutile 구조가 섞여있으며 실리카 기공 내부에 형성된 $TiO_2$는 NaOH 수용액을 이용해서 주형인 KIT-6과 분리해서 메조포어를 지닌 $TiO_2$를 제조하였다.

• Membrane and Water Treatment
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• 제10권5호
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• pp.353-360
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• 2019

ZSM-5 membrane was prepared on tubular macroporous ${\alpha}$-alumina support using a different synthesis route. The effects of organic template agent and Si/Al ratio of the synthesis gel on morphology, structure, and separation performance of the ZSM-5 membrane used for dehydration of isopropanol were investigated. High water perm-selectivity ZSM-5 membrane with a thickness of about $3.0{\mu}m$ and a low Si/Al ratio of 10.1 was successfully prepared from organotemplate-free synthesis gel with a molar composition of $SiO_2$ : $0.050Al_2O_3$ : $0.21Na_2O$ : NaF : $51.6H_2O$ at $175^{\circ}C$ for 24 h. The ZSM-5 membrane exhibited high pervaporation performance with a flux of $3.92kg/(m^2{\cdot}h)$ and corresponding separation factor of higher than 10,000 for dehydration of 90 wt.% isopropanol/water mixture at $75^{\circ}C$.

• 한국환경과학회지
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• 제19권6호
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• pp.681-687
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• 2010

Mesoporous silica was prepared from hydrothermal synthesis using gel mixture of tetraethylorthosilcate (TEOS) as silica source and cetyltrimethylammonium bromide (CTMABr) as a surfactant. In the optimum synthesis cause, molar ratio of template and silica changed. The surface and structure properties of mesoporous silica were determined by XRD, SEM, TEM and BET. Also, surface potential of mesoporous silica was measured using zeta potential. $N_2$ adsorption isotherm characteristics, including the specific surface area ($S_{BET}$), total pore volume $V_T$), and average pore diameter ($D_{BJH}$), were determined by BET. As a result, SBET of $100m^2/g{\sim}1500m^2/g$ was determined from the $N_2$ adsorption isotherm. Also, the average pore diameter was 2 nm∼4 nm. Mesoporous silica's surface potential of minus charge was determined from zeta potential.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.611-611
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• 2013

In this study, iron oxide nanoclusters layer (Nc) was prepared onto functionalized silicon substrate by wet method. The amine-terminated SAM fabricated on silicon substrate (APTMS/Si) was carried out by UV-treatment and immersed into the FeCl3/HCl aqueous solution. Then, Nc were immobilized onto oxidized SAM silicon substrate (SAMs/Si) through electrostatic interaction between cationic Nc and anionic SAMs/Si. This catalytic layer (Nc/SAMs/Si) was used to grow carbon nanotubes (CNTs). The characterization results clearly show that the well-graphitized CNTs were synthesized by using functionalized silicon substrate as a template having appropriate density of catalyst. These consequences show that SAM containing template is important to achieve the effective layer of catalyst to synthesize CNTs.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.184-185
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• 2006

Two-step growth to incorporate the Mg atoms in the ZnO nanorods fabricate by thermal evaporation process and also utilized the ZnO film as a template. In the first step of low temperature, Zn seed metals with low melting temperature formed the droplet, and then MgZnO ternary nanorods were grown by injecting oxygen and evaporating Mg atoms in high temperature process of the second step. The vertical growth of the MgZnO nanorods with large-area distribution and uniformity was successfully performed on the ZnO template. We investigated the shape of the vertically grown 1-D MgZnO nanorods and characterized the optical and crystal properties. We confirmed the incorporation of Mg atoms by the EDS and PL spectrum.