• KSBB Journal
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• 제8권3호
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• pp.300-305
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• 1993

옥수수 종설에 존재하는 brassinosteroid 활생물질 을 탐색하기 위하여 MeOH로 추출하고, 이 추출물을 rice inclination test를 지표로 용매분획, silica g gel adsorption chromatography, Sephadex LH-20 c chromatography, charcoal adsorption chromato­g graphy, bondesil chromatography 등의 수법으로 b brassinosteroid 활생물질을 정제한 다음, silica gel 흡착 chromatography로 활생 성분을 분리하고 H HPLC에 의해 활성 본체를 구명한 결과, castas­t terone과 teasterone이 동정되었는데, 대부분 cas­t tasterone형태로 존재하였다. 옥수수 종실에 함유된 b brassinosteroid함량은 brassinolide로 환산하여 생 체중량 g당 3-8ng 수준이였다.

• Bulletin of the Korean Chemical Society
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• 제32권10호
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• pp.3707-3711
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• 2011

Silver nanoparticles coated with silica can be obtained by the reduction of $AgNO_3$ with hydrazine in the presence of NaOH-stabilized, active silicic acid (polysilicic acid). The size of the silver nanoparticles and the silica shell thicknesses were affected by varying the hydrazine content, the active silicic acid content and the experimental method (e.g. hydrothermal method). Typically, silver nanoparticles sized around 40 nm were aggregated, connected by silica. The presence of peaks centered around 400 nm in UV-vis spectra corresponds to the surface plasmon resonance of silver nanoparticles. The size of the aggregated silver nanoparticles increased with increasing hydrazine concentration. Under hydrothermal conditions at $150^{\circ}C$ the formation of individual silica particles was observed and the sizes of the silver nanoparticles were reduced. The hydrothermal treatment of silver nanoparticles at $180^{\circ}C$ gives a well-defined Ag@$SiO_2$ core-shell in aggregated silica sol particles. The absorption band observed at around 412 nm were red-shifted with respect to the uncoated silver nanoparticles (${\lambda}_{max}$ = 399 nm) due to the larger refractive index of silica compared to that of water. The formation of silver nanoparticles coated with silica is confirmed by UV-visible absorption spectra, transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS) data.

• 한국연초학회지
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• 제16권2호
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• pp.181-190
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• 1994

Various active carbons were made from plant sources of coconut shell, pine tree, oak tree and lignite coal. Pore characteristics of these adsorbents were investigated. 1, With increasing activation time, specific surface area and pore volume increased, but the development of micropores was limited at a certain level. The average pore diameter, by BET, of coconut active carbon was 15.5-21.8$\AA$ and that of lignite carbon was 15.6-31.3$\AA$. The pore diameters of silica-gel, sepiolite and zeolite was 30.9$\AA$, 58.6$\AA$ and 55.7$\AA$, respectively. 2. The Horvath - Kawazoe micropore diameter of coconut shell active carbon was under 10.5$\AA$ and that of the other active carbon was under 20.9$\AA$ but silica-gel 33$\AA$, sepiolite 103 $\AA$ and zeolite was unexpectedly large to be 175$\AA$. From the difference between BET micropore diameter and Howath - Kawazoe diameter, it could be said that silica - gel has comparatively uniform pore diameter but sepiolite and zeolite have very uneven diameter. 3. Total pore volume of coconut shell active carbon was 0.27-1.04 cm3/g but that of the other active carbon, 0.23-0.62 cm3/g, was much lower than that of coconut shell active carbon. Hydrophilic adsorbent silica - gel and sepiolite showed big difference in specific surface area, but pore volumes of these were 0.47 and 0.56 cm3/g showing similar value and micropore volumes of these were, respectively, 0.06 cm3/g and 0.04 cm3/g. Total pore volume of zeolite was 0.1 cm3/g and that of micropore was only 0.02 cm3/g.

• Applied Biological Chemistry
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• 제36권3호
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• pp.197-202
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• 1993

들깨에 존재하는 brassinosteroid 활성물질을 탐색하기 위하여 미숙종자를 MeOH로 추출하고, 이 추출물을 rice inclination test를 지표로, 용매 분획, silica gel adsorption chromatography, Sephadex LH-20 chromatography, charcoal adsorption chromatography, Bondesil chromatography 등의 수법으로 brassinosteroid 활성물질을 정제한 다음, silica gel 흡착 chromatography로 활성성분을 분리하고, 각 활성획분에 대해 HPLC에 의해 활성본체를 구명한 결과, main brassinosteroid로 castasterone이 그리고 minor brassinosteroid로 homodolicholide가 최초로 동정되었다. 들깨에 함유된 brassinosteroid의 함량은 brassinolide로 환산하여 생체중량 g당 $0.5{\sim}0.8\;ng$ 수준이었다.

• 전기화학회지
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• 제16권1호
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• pp.46-51
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• 2013

전극과 용액 사이 계면에서 일어나는 전기화학 반응 현상을 보다 정확하게 이해하기 위하여 전기화학 반응과정을 분광학적 방법으로 실시간으로 모니터링 할 수 있는 전극으로도 작동할 뿐만 아니라 표면증강라만산란(SERS) 활성도 강한 금 마이크로쉘을 제조하였다. 기존에 보고된 금 마이크로쉘에서 핵으로 사용한 폴리스티렌의 경우 균일성이 떨어지고 유기용매에 약하며 독성이 있다. 이에 본 연구에서는 폴리스티렌 보다 균일한 구조를 가지고, 유기 용매에서도 사용 가능하며 무독한 실리카 비드를 이용하여 금 마이크로쉘을 만들고 높은 SERS 신호를 낼 수 있도록 최적화시켰다. $2{\mu}m$ 실리카 비드 표면에 서로 다른 양의 3-aminopropyl triethoxysilane (APTES)를 반응시켜 얻은 금 마이크로쉘에서 SERS 신호가 가장 월등히 증폭되는 조건을 비교한 결과 1% (v/v) APTES 조건에서 SERS 신호의 증폭이 가장 컸다. 표면증강라만산란 스펙트럼 및 전계방출형 주사전자현미경(FE-SEM) 이미지를 통해 금 마이크로쉘을 분석하였다.

• Applied Biological Chemistry
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• 제39권4호
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• pp.265-267
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• 1996

The methanol extracts of AraIia elata showed antimicrobial activity against bacteria. The antimicrobial active principle was successively purified with solvent fractionation, silica gel adsorption column chromatography, Sephadex LH-20 column chromatography, silica gel partition column chromatography and HPLC. The active substance was isolated by HPLC on $C_{18}$ column with an acetic acid-MeOH system. The active substance was identified as trans-4-hydroxycinnamic acid by MS, $^1H-NMR\;and\;^{13}C-NMR$.

• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2419-2421
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• 2009

A simple and efficient method has been developed for Knoevenagel condensation between aldehydes or ketones and active methylene group by stirring in methylene chloride at 60 ${^{\circ}C}$ under heterogeneous conditions using silica supported ammonium acetate. The products are obtained in excellent yields and are in a state of high purity. The structures of the products were confirmed by IR, $^1H$ NMR and mass spectral data and comparison with authentic samples available commercially.

• Bulletin of the Korean Chemical Society
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• 제35권9호
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• pp.2765-2768
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• 2014

Flower-like Au nanoparticles, so-called Au nanoflowers (AuNFs), were synthesized by simply adding ascorbic acid to a gold acid solution in the presence of a chitosan biopolymer. The chitosan-entangled AuNFs exhibited strong plasmon absorption in the near-infrared (NIR) wavelength due to the aggregation of primary Au nanoparticles. The chitosan-entangled AuNFs were preferentially adsorbed by Raman-active 2-chlorothiophenol (CTP) molecules, and the CTP-encoded AuNFs (AuNF-CTPs) were subsequently coated with a thin silica layer by a sol-gel reaction with Si alkoxides. The silica-coated AuNFs (AuNF-CTPs@silica) exhibited the distinct Raman signals of adsorbed CTP molecules, as a potential nanoprobe with surface-enhanced Raman scattering (SERS).

• Journal of Applied Biological Chemistry
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• 제51권4호
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• pp.143-147
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• 2008

Purified atrazine chlorohydrolase (AtzA) was entrapped in the nanoparticles of biomimetically synthesized silica at the ambient condition within 20 min. Entrapped AtzA in biomimetic silica was less affected by pH change and showed higher thermostability than free enzymes. The entrapped AtzA was also more tolerant against proteolysis, with 80% of the initial activity remaining and retained 82% of the initial activity even after four cycles of usage. These results suggest that entrapment of AtzA in biomimetic silica could be utilized under diverse environmental conditions with the active catalytic performance sustained.

• 농업과학연구
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• 제48권2호
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• pp.343-351
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• 2021

Screening was conducted using 200 kinds of plant extracts to explore herbicide-activated components of plant origin. We separated and purified active substances and elucidated chemical structures using Ligularia stenocephala M., which has strong activity and has not yet been studied. When the solvent fractions of the leaves of Ligularia stenocephala M. were tested for their herbicidal activity, ethyl acetate and chloroform layer showed an inhibition rate of 95.2% and 94.1%, respectively. In particular, the chloroform layer exerted more than 50% herbicidal activity at 10 ppm. From the chloroform layer with the highest herbicidal activity, we isolated three herbicidal active compounds using stepwise chromatography, specifically silica gel or octadecyl silica (ODS) column chromatography, Sep-pak cartridges, and high performance liquid chromatography (HPLC). Based on the analysis of the active compounds using electron ionization mass spectroscopy (EI-MS), ¹H-NMR, and ¹³C-NMR, we identified the active compounds as euparin, 5,6-dimethoxy-2-isopropenylbenzofuran, and liguhodgsonal. When the herbicidal activity of the identified compounds was tested, euparin showed selective herbicidal activity for lettuce at 10^-3 M, and both liguhogsonal and 5,6-dimethoxy-2-isoprophenylbenzofuran exerted selective activity for rice and Echinochloa crus-galli.