• 통합자연과학논문집
• /
• 제14권1호
• /
• pp.6-10
• /
• 2021

New materials are very useful due to their wide range of applications, however, they also have caused new pollutants that damage our environment. Chemists have been conscious of the severity of these environmental problems and a great deal of effort has been put into developing environmentally benign chemical processes to synthesize new materials (green synthesis). We also have reported a green synthesis method of synthesizing silver nanoparticles using water-glycerol solution in a previous study. While conducting further research, we have recently discovered that the size of silver nanoparticles is proportional to the quantity of water present in glycerol. This method is completely benign and ecofriendly pathway, as the size of silver nanoparticles is adjusted solely by controlling the quantity of water added to glycerol, without extra additives and energy.

• 한국세라믹학회지
• /
• 제37권8호
• /
• pp.745-750
• /
• 2000

YAG:Tb3+ as green phosphor were studied for the development of low voltage FED phosphor prepared by hydrothermal synthesis. We changed the concentration of luminescence center ion Tb3+ in hydrothermal reaction of which conditions were at 8M NH4OH as mineralizer, at 35$0^{\circ}C$ for 12hrs. As results, we could finally get the YAG:Tb3+ (Y3-xTbxAl5O12) powder of which particle size was about 0.2~1.0${\mu}{\textrm}{m}$. The excitation spectra and the green emitted spectra of YAG:Tb3+ phosphor powder were observed. When we doped 0.25 mol Tb to YAG, we could observe the maximum cathodoluminescence from YAG:Tb3+ phosphor and the chromaticity coordinate of the phosphor was shown x=0.35, y=0.56 in CIE1931 diagram.

• Journal of Industrial and Engineering Chemistry
• /
• 제68권
• /
• pp.33-41
• /
• 2018

The manuscript reports synthesis of exceptionally stable gold nanoparticles (GNPs) using Momordica charantia fruit extract. The synthesis approach was optimized by refining three experimental variables including source of the fruit extract (peel, seed, and seed coat), pH of the solution, and temperature of the reaction medium. As synthesized GNPs showed excellent stability against various thiolated compounds (e.g., thioglycolic acid, thiourea, ${\text\tiny{L}}-cystine$, 1-dodecanethiol, and cysteamine hydrochloride). Moreover, these nanoparticles showed distinctive colorimetric responses against $Cd^{2+}$ and thiophenol (TP) from their potential interferences. The limit of detection (LOD) values for $Cd^{2+}$ and TP were determined as 0.186 and $0.154{\mu}M$, respectively.

• 한국식품영양과학회지
• /
• 제44권10호
• /
• pp.1470-1475
• /
• 2015

본 연구는 산업 부산물의 이용성 향상을 위하여 폐자원인 녹차씨 껍질 추출물의 미백 활성을 평가하기 위하여 수행되었다. 녹차씨 껍질로부터 유용성 성분을 얻기 위하여 에탄올 추출을 한 결과 건조중량 대비 1.24%의 추출물의 수율을 얻을 수 있었고, DPPH 라디칼 소거능 및 tyrosinase 억제능을 관찰한 결과 녹차씨 껍질 추출물의 농도가 증가할수록 활성이 유의적으로 증가하는 것으로 나타났다. 또한 이러한 미백 효과가 세포 내에서도 일어나는지에 관하여 알아보기 위하여 melanoma 세포인 B16BL6에 ${\alpha}$-MSH를 처리하여 melanin의 형성을 촉진시키는 melanogenesis 과정을 유도한 후 녹차씨 껍질 추출물을 처리한 결과 농도 의존적으로 melanin의 형성이 감소되는 것을 알 수 있었다. 이상의 결과로 녹차씨 껍질 추출물의 미백 활성을 확인할 수 있었으며, 이를 활용하여 식품 및 화장품의 기능성 소재로 이용한다면 산업 부산물인 녹차씨 껍질을 활용하는 차원에서 그 경제적 가치가 매우 클 것으로 사료된다.

• Bulletin of the Korean Chemical Society
• /
• 제31권12호
• /
• pp.3519-3520
• /
• 2010

• 대한화학회지
• /
• 제64권4호
• /
• pp.236-238
• /
• 2020

• Bulletin of the Korean Chemical Society
• /
• 제32권10호
• /
• pp.3559-3560
• /
• 2011

• 대한화장품학회지
• /
• 제32권2호
• /
• pp.117-121
• /
• 2006

collagen을 분해하여 광노화 과정에 매우 중요한 역할을 하는 것으로 알려져 있는 Matrix metallo proteinases (MMP)의 활성 및 저해 인자에 대해서는 지금까지 많은 연구가 진행되어 왔지만, 녹차 카테킨의 영향에 대한 연구는 epigallocatechin-3 gallate (EGCG) 이외에는 별로 알려진 것이 없다. 본 연구에서는 카테킨이 사람 섬유아세포에서의 MMP-1의 발현과 MMP-2의 활성 및 type I procollagen 생성에 미치는 영향을 조사하였다. 또한, 녹차의 대표적인 카테킨인 EGCG를 포함하여 자연적으로 존재하는 여덟개의 카테킨을 모두 사용하여 각각의 활성을 비교하였다. 그 결과, UVA에 의해서 사람 섬유아세포에서 발현되는 MMP-1에 대해 단백질의 양적인 변화는 EGCG 및 gallocatechin-3-gallate (GCG)에서 최대 57.4, 62.8% 감소되었으며, MMP-2의 활성 역시 감소되었다. 반면에, type I procollagen에 대해서는 생성 촉진능을 보였는데, 흥미롭게도 $1{\mu}M$ 이하의 저농도에서만 효능을 나타내었다. 또한 EGCG, GCG, epicatechin-gallate (ECG) 세가지 카테킨이 0.5:1.5:1.3의 비율로 조합된 경우, procollagen 합성에 가장 높은 효과를 나타내었다. 이러한 실험 결과를 통해 녹차 카테킨은 항산화능 뿐만이 아니라 자외선에 의한 MMP의 발현과 활성을 조절함으로써 콜라겐 분해를 억제함과 동시에 콜라겐 생합성을 촉진하는 것이 가능함을 확인하였다. 따라서 녹차 카테킨은 광노화의 억제 및 피부 노화 개선에 훌륭한 천연 소재로서 응용 가능할 것으로 보인다.

• 한국군사과학기술학회지
• /
• 제16권5호
• /
• pp.690-702
• /
• 2013

Ionic liquids(ILs) have been the most investigated chemicals among green solvents including water, glycerol, supercritical carbon dioxdie($scCO_2$). ILs are attracting organic as well as inorganic chemicals because most ionic liquids' vapor pressures are very low so that ILs are liquids phase at ambient conditions. ILs are composed of various anions and cations, thus chemists can design functionalized solvents and/or catalysts that can be used in specific synthetic reactions by means of combinations of different ions. Many scientists believe ILs being green materials because of its low vapor pressure as well as the flexibility in controlling the chemical and physical properties. In this review the author describes recent development of ILs focused on imidazolium and pyridinium ILs which are being most investigated presently. In order to apply this materials in industrial level, the toxicity matter must be resolved first. In this regard, the author describes recent research trend regarding environmental effects by ILs as well as some meaningful results as well.

• Bulletin of the Korean Chemical Society
• /
• 제35권6호
• /
• pp.1659-1664
• /
• 2014

A porous metal-organic framework (MOF), MIL-101, was synthesized in the presence of sulfated zirconia (SZ) to produce acidic SZ/MIL-101 composites for the first time. The composites were characterized with XRD, nitrogen adsorption, FT-IR, scanning electron microscope, chemical analysis and so on. The composites (SZ/MIL-101s) were successfully applied in a liquid-phase esterification for a high yield of ester. This catalytic result of SZ/MIL-101, compared with that of pure SZ or MIL-101 (showing a negligible yield of ester), suggests that the SZ in the composite is highly active in the acid catalysis probably because of the well-dispersed active species of SZ. Moreover, the esterification is catalyzed in heterogeneous mode as confirmed by negligible esterification after filtration of the catalyst. Finally, microwaves can be efficiently applied both in the synthesis of the composites and the esterification reaction to accelerate the two processes of synthesis and esterification by about 5 times.