• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.200-200
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• 2011

Hierarchical mesoporous ZSM-5 with enhanced mesoporosity was synthesized by microwave through the rapid assembly via ionic interaction between sulfonic acid functionalized ZSM-5 nano particles and cationic surfactant. The catalytic performance of enhanced accessibility due to mesoporosity and acidity were investigated in the alkylation of mesitylene with benzyl alcohol as alkylating agent. The effect of mole ratio of aromatic with benzyl alcohol, reaction time and alkylation agent were also studied. The enhanced mesoporosity and acidity of sulfonic acid functionalized mesoporous ZSM-5 induced activity enhancement compared with non-functionalized mesoporous ZSM-5, sulfonic functionalized mesoporous ZSM-5 synthesized by hydrothermal method and conventional microporous ZSM-5. The sulfonic acid functionalized mesoporous ZSM-5 showed much higher chemoselectivity of benzylated mesitylene than others, whereas the others mainly show dibenzyl ether as product. This significant difference in catalytic selectivity was resulted from the existence of mesopores, which definitely allowed the benzylation in mesopores.

• 한국분말재료학회지
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• 제14권2호
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• pp.127-131
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• 2007

The alumina nano powders synthesized by levitational gas condensation (LGC) method were applied to catalyst in manufacturing process of Hanzsch reaction for Nitrendipine. The L-tartaric acid on the surface is carried out with participation of carbonyl fragments, O-H, C-H bonds which affects stereo selectivity, yield on the reagents positively. From the analysis of the IR-spectroscopy, the carbonyl fragments, O-H, and C-H bond were created by the catalytic reaction. From the analysis of the rR-spectroscopy, the carbonyl fragments, O-H, and C-H bond were created by the catalytic reaction. The newly created bonds made a chiral center on the final product.

• Transactions on Electrical and Electronic Materials
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• 제13권6호
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• pp.287-291
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• 2012

We investigated the etching characteristics of TaN thin films in an $O_2/BCl_3/Cl_2/Ar$ gas using a high density plasma (HDP) system. A maximum etch rate of the TaN thin films and the selectivity of TaN to $SiO_2$ were obtained as 172.7 nm/min and 6.27 in the $O_2/BCl_3/Cl_2/Ar$ (3:2:18:10 sccm) gas mixture, respectively. At the same time, the etch rate was measured as a function of the etching parameters, such as the RF power, DC-bias voltage, and process pressure. The chemical states on the surface of the etched TaN thin films were investigated using X-ray photoelectron spectroscopy. Auger electron spectroscopy was used for elemental analysis on the surface of the etched TaN thin films. These surface analyses confirm that the surface of the etched TaN thin film is formed with the nonvolatile by-product.

• 대한화학회지
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• 제58권1호
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• pp.17-24
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• 2014

The oxidative decarboxylation of phenylsulfinylacetic acid (PSAA) by Cr(VI) in 20% acetonitrile -80% water (v/v) medium follows overall second order kinetics, first order each with respect to [PSAA] and [Cr(VI)] at constant [$H^+$] and ionic strength. The reaction is acid catalysed, the order with respect to [$H^+$] is unity and the active oxidizing species is found to be $HCrO_3^+$. The reaction mechanism involves the rate determining nucleophilic attack of sulfur atom of PSAA on chromium of $HCrO_3^+$ forming a sulfonium ion intermediate. The intermediate then undergoes ${\alpha}$,${\beta}$-cleavage leading to the liberation of $CO_2$. The product of the reaction is found to be methyl phenyl sulfone. The operation of substituent effect shows that PSAA containing electron-releasing groups in the meta- and para-positions accelerate the reaction rate while electron withdrawing groups retard the rate. An excellent correlation is found to exist between log $k_2$ and Hammett ${\sigma}$ constants with a negative value of reaction constant. The ${\rho}$ value decreases with increase in temperature evidencing the high reactivity and low selectivity in the case of substituted PSAAs.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.51-51
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• 2012

There is a growing interest in innovative chemical synthesis in microreactors owing to high efficiency, selectivity, and yield. In microfluidic systems, the low-volume spatial and temporal control of reactants and products offers a novel method for chemical manipulation and product generation. Glass, silicon, poly(dimethylsiloxane) (PDMS), and plastics have been used for the fabrication of miniaturized devices. However, these materials are not the best due to either of low chemical durability or expensive fabrication costs. In our group, we have recently addressed the demand for economical resistant materials that can be used for easy fabrication of microfluidic systems with reliable durability. We have suggested the use of various specialty polymers such as silicon-based inorganic polymers and fluoropolymer, flexible polyimide (PI) films that have not been used for microfluidic devices, although they have been used for other areas. And inexpensive lithography techniques were used to fabricate Lab-on-a-Chip type of microreactors with differently devised microchannel design. These microreactors were demonstrated for various synthetic reactions: liquid, liquid-gas organic chemical reactions in heterogeneous catalytic processes, syntheses of polymer and non-trivial inorganic materials. The microreactors were inert, and withstand even harsh conditions, including hydrothermal reaction. In addition, various built-in microstructures inside the microchannels, for example Pd decorated peptide nanowires, definitely enhance the uniqueness and performance of microreactors. These user-friendly Lab-on-a-Chip devices are useful alternatives for chemist and chemical engineer to conventional chemical tools such as glass.

• 대한화학회지
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• 제25권1호
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• pp.26-29
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• 1981

양이온 교환 및 알루미늄 추출시킨 모더나이트와 제올라이트 Y 촉매에서 m-크실렌의 반응이 마이크로펄스방법으로 연구되었다. H-모더나이트 촉매에서 전처리온도가 높아지거나 Si/Al비가 증가할 때 동종간 주고 받기반응생성물이 크게 증가했다. $Ba^{2+}-, Mg^{2+}- $이온교환한 모더나이트촉매에서 양이온교환정도가 증가할에따라 트리메틸벤젠의 생성량이 급격히 감소했다. m-크실렌의 동종간 주고 받기반응에서는 모더나이트의 산성도의 영향과 아울러 촉매 유효세공의 크기에 따른 형상 선택성을 보여준다.

• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3657-3664
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• 2012

Reactions of 1-adamantylmethyl chloroformate ($1-AdCH_2OCOCl$, 1) and 1-adamantylmethyl fluoroformate ($1-AdCH_2OCOF$, 2) in hydroxylic solvents have been studied. Application of the extended Grunwald-Winstein (G-W) equation to solvolyses of 1 in a variety of pure and binary solvents indicates an addition-elimination pathway in the majority of the solvents except an ionization pathway in the solvents of relatively low nucleophilcity and high ionizing power. The solvolyses of 2 show an addition-elimination pathway in all of the mixed solvents. The leaving group effects ($k_F/k_{Cl}$), the kinetic solvent isotope effects (KSIEs, $k_{MeOH}/k_{MeOD}$), and the enthalpy and entropy of activation for the solvolyses of 1 and 2 were also calculated. The selectivity values (S) for each solvent composition are reported and discussed. These observations are compared with those previously reported for other alkyl haloformate esters.

• Natural Product Sciences
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• 제24권4호
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• pp.219-224
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• 2018

During the screening for cytotoxic compounds from plants grown in Korea, Betula platyphylla (BP) showed potent activity against the adenocarcinomic human alveolar basal epithelial A549 cell line. To identify the cytotoxic components from BP, the $CH_2Cl_2$ fraction with the most significant cytotoxic effect was applied to the column chromatographies. Seven compounds were isolated: lupeol (1), betulinic acid (2), (-)-rhododendrol (3), platyphyllenone (4), platyphyllone (5), (-)-centrolobol (6), and oleanolic acid (7). Among them, three diarylheptanoids (4 - 6) exhibited cytotoxicity toward A549 cells. Especially, $50{\mu}M$ of 4 reduced A549 cell viability to $18.93{\pm}0.82%$ compared to control ($100.00{\pm}21.48%$). Lactate dehydrogenase (LDH) leakage and intracellular reactive oxygen species (ROS) production were also induced by $50{\mu}M$ 4. This is the first report on the cytotoxic effect of BP-derived diarylheptanoids 4-6 against A549 cells. The compound 4 may be useful for the development of early hit compounds for non-small cell lung carcinoma, but the consideration about selectivity of 4 is required since 4 also showed the cytotoxicity in the human normal lung epithelial BEAS-2B cell line.

• Natural Product Sciences
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• 제25권2호
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• pp.115-121
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• 2019

Alzheimer's disease is a chronic neurodegenerative disorder with no curative treatment. The commercially available drugs, which target acetylcholinesterase, are not satisfactory. The aim of this study was to investigate the cholinesterase inhibitory activity of Solenostemma argel aerial part. Eight compounds were isolated and identified by NMR: kaempferol-3-O-glucopyranoside (1), kaempferol (2), kaempferol-3-glucopyranosyl($1{\rightarrow}6$)rhamnopyranose (3) p-hydroxybenzoic acid (4), dehydrovomifoliol (5), 14,15-dihydroxypregn-4-ene-3,20-dione (6), 14,15-dihydroxy-pregn-4-ene-3,20-dione-$15{\beta}$-D-glucopyranoside (7) and solargin I (8). Two of them (compounds 2 and 3) could inhibit over 50 % of butyrylcholinesterase activity at $100{\mu}M$. Compound (2) displayed the highest inhibitory effect against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with a slight selectivity towards the latter. Molecular docking studies supported the in vitro results and revealed that (2) had made several hydrogen and ${\pi}-{\pi}$ stacking interactions which could explain the compound potency to inhibit AChE and BChE.

• Korean Chemical Engineering Research
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• 제49권5호
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• pp.521-529
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• 2011

원형 세공과 선형 세공이 독립적으로 발달한 MWW와 구부러진 세공과 선형 세공이 서로 교차하는 MFI 제올라이트에서 세공 구조가 메탄올의 저급 올레핀으로 전환(MTO) 반응에서 생성물 분포와 활성 저하에 미치는 영향을 조사하였다. 산성도가 비슷한 MWW와 MFI 제올라이트는 MTO 반응에서 전환율이 높고 활성 저하가 느린 점이 서로 비슷하지만, MWW에서는 $C_3-C_9$의 선형 탄화수소가 많이 생성되나 MFI에서는 $C_2{^=}$와 방향족 화합물의 수율이 높았다. MTO 반응 중 MWW에는 다고리 방향족 화합물(PAHs)이 많이 축적되나 MFI에서는 벤젠과 나프탈렌 유도체만 생성되었다. MFI와 달리 MWW에 인을 담지하면 MTO 반응에서 촉매 활성과 톨루엔의 흡착량이 크게 줄었다. MWW의 선형 세공에는 MTO 반응 중 PAHs가 축적되어 활성이 없어지나 PAHs가 생성되지 않은 원형 세공에서 선형 탄화수소가 생성된다. 그러나 원형 세공에 인이 담지되면 세공이 막혀 활성이 크게 줄어든다. MFI에는 세공 교차 부분에 인이 담지되어 강한 산점이 중화되어 생성물 분포는 달라지나 활성은 저하되지 않았다. 세공 구조의 차이로 MTO 반응에서 MWW와 MFI의 촉매로서 거동 차이를 설명하였다.