• 한국산학기술학회논문지
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• 제15권1호
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• pp.39-46
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• 2014

미얀마 Kayah산 녹색 투어말린의 특성을 X-선 형광분석, 자외선-가시광선 그리고 중적외선 분광분석을 통하여 타산지의 녹색 투어말린과 비교하였다. 화학성분 분류에 의해 미얀마 투어말린이 속한 그룹을 조사 하였다. 미얀마 투어말린은 V 원소를 많이 함유하고 있었고 X 사이트에 Ca 원소를 반 이상 함유한 Calcic 그룹에 속했고 우바이트 (Uvite)로 명명되었다. 자외선-가시광선 분석결과 $V^{3+}$ 이온에 의한 415와 611 nm에 강한 흡수밴드가 나타나 녹색 투어말린의 원인이 되었다. $Fe^{2+}$ 이나 $Cu^{2+}$ 이온에 의해 녹색이 나타나는 타산지의 녹색 투어말린과 차이가 있었다. 중적외선 분석에서는 수산기와 금속들 간의 진동에 의한 흡수가 일어났는데 1100 $cm^{-1}$ 근처에서 스트레칭 모드, 3500 $cm^{-1}$ 주변에서 벤딩 모드 그리고 4600과 4200 $cm^{-1}$ 사이에서 스트레칭과 벤딩 모드의 혼합 밴드가 나타났다.

• Bulletin of the Korean Chemical Society
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• 제27권3호
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• pp.368-372
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• 2006

The cobalt titanate, $CoTiO_3$ nanoparticles have been prepared by calcinations of precursor obtained from a mixture of $TiO_2$ and $Co(OH)_2$ in aqueous cetyltrimethylammonium bromide (CTAB) solution. The nanoparticles were investigated with X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric/differential thermal analysis (TGA/DTA) to determine the crystallite size and the phase composition. The spectroscopic characterizations of these nanoparticles were also done with UV-Vis spectroscopy and FT-Raman spectroscopy. XRD patterns show that $CoTiO_3$ phase was formed at calcinations temperature above 600 ${^{\circ}C}$. UV-Vis absorption spectra indicate that the $CoTiO_3$ nanoparticles have significant red shift to the visible region (400-700 nm) with $\lambda_{max}$ = 500 nm compared to pure $TiO_2$ powder ($\lambda_{max}$ = 320 nm). The new absorption peaks (absorption at 696, 604, 520, 478,456, 383, 336, 267, 238, 208 $c m ^{-1}$), which were not appeared in FT-Raman spectra of P-25, also confirm the formation of Ti-O-Co bonds at above 600 ${^{\circ}C}$ and just not the mixtures of titanium dioxide with cobalt oxides.

• Bulletin of the Korean Chemical Society
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• 제31권8호
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• pp.2170-2174
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• 2010

The surfaces of $TiO_2$ and ZnO nanoparticles have been modified by gold (Au) nanoparticles by a reduction method in solution. Their interfacial electronic structures and optical absorptions have been studied by depth-profiling X-ray photoelectron spectroscopy (XPS) and UV-vis absorption spectroscopy, respectively. Upon Au-modification, UV-vis absorption spectra reveal a broad surface plasmon peak at around 500 nm. For the as-prepared Au-modified $TiO_2$ and ZnO, the Au $4f_{7/2}$ XPS peaks exhibit at 83.7 and 83.9 eV, respectively. These are due to a charge transfer effect from the metal oxide support to the Au. For $TiO_2$, the larger binding energy shift from that (84.0 eV) of bulk Au could indicate that Au-modification site of $TiO_2$ is different from that of ZnO. On the basis of the XPS data with sputtering depth, we conclude that cationic (1+ and 3+) Au species, plausibly $Au(OH)_x$ (x = 1-3), commonly form mainly at the Au-$TiO_2$ and Au-ZnO interfaces. With $Ar^+$ ion sputtering, the oxidation state of Ti dramatically changes from 4+ to 3+ and 2+ while that (2+) of Zn shows no discernible change based on the binding energy position and the full-width at half maximum (FWHM).

• Journal of Microbiology and Biotechnology
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• 제24권4호
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• pp.453-464
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• 2014

The current research was focused on the extracellular biosynthesis of bactericidal silver nanoparticles (AgNPs) using cell-free supernatant of a local isolate previously identified as a novel Streptomyces aegyptia NEAE 102. The biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102 was quite fast and required far less time than previously published strains. The produced particles showed a single surface plasmon resonance peak at 400 nm by UV-Vis spectroscopy, which confirmed the presence of AgNPs. Response surface methodology was chosen to evaluate the effects of four process variables ($AgNO_3$ concentration, incubation period, pH levels, and inoculum size) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. Statistical analysis of the results showed that the linear and quadratic effects of incubation period, initial pH, and inoculum size had a significant effect (p < 0.05) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. The maximum silver nanoparticles biosynthesis (2.5 OD, at 400 nm ) was achieved in runs number 5 and 14 under the conditions of 1 mM $AgNO_3$ (1-1.5% (v/v)), incubation period (72-96 h), initial pH (9-10), and inoculum size (2-4% (v/v)). An overall 4-fold increase in AgNPs biosynthesis was obtained as compared with that of unoptimized conditions. The biosynthesized silver nanoparticles were characterized using UV-VIS spectrophotometer and Fourier transform infrared spectroscopy analysis, in addition to antimicrobial properties. The biosynthesized AgNPs significantly inhibited the growth of medically important pathogenic gram-positive (Staphylococcus aureus) and gram-negative bacteria (Pseudomonas aeruginosa) and yeast (Candida albicans).

• 공업화학
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• 제32권2호
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• pp.163-167
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• 2021

본 연구에서는 타이로신이 풍부한 펩타이드, Tyr-Tyr-Leu-Tyr-Tyr (YYLYY)를 이용하여 금 나노입자를 담지한 균일한 금-펩타이드 계층적 초분자 구조체의 합성에 대해 연구하였다. 펩타이드의 광가교 반응을 통해 다이타이로신 결합으로 자기조립된 펩타이드 나노입자를 합성하였고, 타이로신의 생체 광물화 특성을 이용하여 금-펩타이드 하이브리드 나노입자를 친환경적 방법으로 합성하였다. 합성된 금-펩타이드 하이브리드 나노입자는 투과 전자 현미경(TEM), 주사투과 전자 현미경(SEM), 동적 광산란(DLS), 자외선-가시광선 분광광도계(UV-Vis spectroscopy), 에너지 분산 X선 분광법(STEM-EDS), X선 회절 분석법(XRD)을 통해 분석하였다. 또한 합성된 금-펩타이드 하이브리드 나노입자는 메틸렌블루의 환원 반응에서 13.4 × 10-3 s-1의 반응속도 상수를 가지는 촉매 특성을 확인하였다.

• 한국광물학회지
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• 제22권4호
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• pp.385-393
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• 2009

마다가스카르 산 투어말린의 보석광물학적 특징들을 알기 위해 물리적 특성, 원소분석, 내포물 분석, 그리고 분광분석(UV-VIS 분광기, FTIR 분광기)을 하여 다른 산지와 비교 연구하였다. 물리적 특성은 다른 산지의 것과 큰 차이를 보이지 않았다. 자외선-가시광선 분광분석 결과 녹색과 청색의 시료는 Fe 성분이 많아 $Fe^{3+}$에 의한 714~743 nm 영역에서 높은 흡수 밴드가 나타났고 분홍색은 $Mn^{3+}$에 의해 510~530 nm에서 높은 흡수를 보였다. 갈색 시편은 Mn이 많아 $Mn^{2+}-Ti^{4+}$ 전하전이에 의해서 325 nm의 자외선 영역에서 나타난 높은 흡수에 기인하였다. 또한 무색 시편에서는 $Mn^{2+}$에 의한 406~413 nm 사이의 밴드가 매우 미약하거나 Mn의 양이 적어 $Mn^{2+}$의 영향이 거의 없어 발색이 되지 않았다고 본다. 적외선 분광분석에서는 4300~4500 $cm^{-1}$ 영역에서 금속-OH의 스트레칭과 밴딩이 조합된 모드에 의한 여러 개의 흡수 밴드가 나타났다. 내포물에서는 평행한 관상 속에 적철석이 녹아있는 형태가 나타났다. 연구 결과 마다가스카르 산의 투어말린은 Cu는 검출되지 않았으나 Fe과 Mn이 모두 검출되었고 이들의 양에 따라 다양한 색상이 나타남을 확인할 수 있었고 물리적 특성과 적외선 영역의 흡수 밴드, 그리고 내포물들은 다른 산지와 큰 차이를 보이지 않았음을 확인할 수 있었다.

• Elastomers and Composites
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• 제45권1호
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• pp.25-31
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• 2010

우리는 탄소 전구체로 활성탄 (AC), 활성탄 섬유 (ACF)와 탄소나노튜브 (MWCNT)와 티타늄 전구체로써 TNB를 사용하여 탄소-$TiO_2$ 복합체를 제조하였으며, 이들의 특성을 SEM, TEM, BET, XRD와 EDX를 이용하여 분석하였다. 그리고 이들의 광촉매 활성은 UV 램프 조사에서 일정한 농도의 MB 용액을 이용하여 측정하였다. UV 조사한 후에 MB의 농도는 UV-vis 분광광도기를 이용하여 측정하였다.

• Bulletin of the Korean Chemical Society
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• 제35권8호
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• pp.2523-2528
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• 2014

In the present study, at first, azo Schiff base ligand of (N,N'-bis(5-phenylazosalicylaldehyde)-ethylenediamine) ($H_2L$) has been synthesized by condensation reaction of 5-phenylazosalicylaldehyde and ethylenediamine in 2:1 molar ratio, respectively. Then, its cobalt complex (CoL) was synthesized by reaction of $Co(OAc)_2{\cdot}4H_2O$ with ligand ($H_2L$) in 1:1 molar ratio in ethanol solvent. This ligand and its cobalt complex containing azo functional groups were characterized using elemental analysis, $^1H$-NMR, UV-vis and IR spectroscopies. Subsequently, the interaction between native calf thymus deoxyribonucleic acid (ct-DNA) and CoL complex was investigated in 10 mM Tris/HCl buffer solution, pH = 7 using UV-vis absorption, thermal denaturation technique and viscosity measurements. From spectrophotometric titration experiments, the binding constant of CoL complex with ct-DNA was found to be $(2.4{\pm}0.2){\times}10^4M^{-1}$. The thermodynamic parameters were calculated by van't Hoff equation.The enthalpy and entropy changes were $5753.94{\pm}172.66kcal/mol$ and $43.93{\pm}1.18cal/mol{\cdot}K$ at $25^{\circ}C$, respectively. Thermal denaturation experiments represent the increasing of melting temperature of ct-DNA (about $0.93^{\circ}C$) due to binding of CoL complex. The results indicate that the process is entropy-driven and suggest that hydrophobic interactions are the main driving force for the complex formation.

• Journal of Microbiology and Biotechnology
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• 제24권4호
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• pp.522-533
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• 2014

Bionanotechnology has revolutionized nanomaterial synthesis by providing a green synthetic platform using biological systems. Among such biological systems, microalgae have tremendous potential to take up metal ions and produce nanoparticles by a detoxification process. The present study explores the intracellular and extracellular biogenic syntheses of silver nanoparticles (SNPs) using the unicellular green microalga Scenedesmus sp. Biosynthesized SNPs were characterized by AAS, UV-Vis spectroscopy, TEM, XRD, FTIR, DLS, and TGA studies and finally checked for antibacterial activity. Intracellular nanoparticle biosynthesis was initiated by a high rate of $Ag^+$ ion accumulation in the microalgal biomass and subsequent formation of spherical crystalline SNPs (average size, 15-20 nm) due to the biochemical reduction of $Ag^+$ ions. The synthesized nanoparticles were intracellular, as confirmed by the UV-Vis spectra of the outside medium. Furthermore, extracellular synthesis using boiled extract showed the formation of well scattered, highly stable, spherical SNPs with an average size of 5-10 nm. The size and morphology of the nanoparticles were confirmed by TEM. The crystalline nature of the SNPs was evident from the diffraction peaks of XRD and bright circular ring pattern of SAED. FTIR and UV-Vis spectra showed that biomolecules, proteins and peptides, are mainly responsible for the formation and stabilization of SNPs. Furthermore, the synthesized nanoparticles exhibited high antimicrobial activity against pathogenic gram-negative and gram-positive bacteria. Use of such a microalgal system provides a simple, cost-effective alternative template for the biosynthesis of nanomaterials in a large-scale system that could be of great use in biomedical applications.

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권6호
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• pp.216-219
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• 2003

A new class of carbosiloxane dendrimer (G4-48PyP) terminated with 4-pyridylpropano I was synthesized and its possible application to functional thin films was examined through metal complexation and Langmuir-Blodgett (LB) technique. The highly concentrated periphery pyridyl groups of G4-48PyP were exposed on aq. aluminum ions at the air-water interface. The monolayers showed stability up to ca. 50 mN/m of surface pressure. When the subphase became acidic or alkaline, the monolayers changed to condensed phase. The presence of aluminum ions also caused reduction of the molecular area. The macroscopic images of the monolayers were monitored by Brewster angle microscopy (BAM) and only the images of dendrimer aggregates could be observed after the monolayer collapse. The surface images of the monolayer LB film were scanned by atomic force microscopy (AFM). The convex structures of single and aggregate molecules were directly observed. The structures of Langmuir-Blodgett (LB) films were characterized by FT-IR, UV-Vis, and X-ray photoelectron spectroscopy (XPS). The UV-Vis spectrum of the aluminum ion-complexed LB film showed additional band around 670nm, which was not found in the spectra of dendrimer itself or aq. aluminum ions. XPS spectra also supported the incorporation of aluminum ions into the LB films.