• 대한화학회지
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• 제20권5호
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• pp.398-405
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• 1976

메틸 피라진과 피라진산으로 부터 새로운 화합물 1,2-비스피라진 에틸렌을 합성하여 기기분석과 원소분석으로 이 화합물의 구조를 확인하였다. UV-VIS 스펙트럼에서는 예상했던 $(n,\;{\pi}^*)^1$ 흡수띠가 흡광도가 강한 $({\pi},\;{\pi}^*)^1$ 흡수띠에 묻혀 볼 수가 없었으나 형광에 미치는 염의 효과로 부터 $(n,\;{\pi}^*)^1$ 상태가 $({\pi},\;{\pi}^*)^1$ 상태와 거의 같은 에너지를 갖고 있음을 알았다. $77^{\circ}K$에서 형광의 양자 수득률은 0.025로서 같은 조건에서 형광 양자 수득륙이 1인 스틸벤과 좋은 대조를 이루며 이는 $(n,\;{\pi}^*)$와 $({\pi},\;{\pi}^*)$의 혼합으로 단일 상태에서 삼중 상태로의 intersystem crossing이 효율적으로 잘 일어난다는 것을 말해 준다.

• 한국응용과학기술학회지
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• 제33권1호
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• pp.136-142
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• 2016

무질서 매질에서 형광, 산란과 응집의 영향은 파장과 산란된 형광세기로 나타내는데, laser induced fluorescence(LIF) 분광학에 의한 분자특성으로 나타난다. 산란매질에서 광학적 효과는 광학적 파라미터들(${\mu}_s$, ${\mu}_a$, ${\mu}_t$)에 의해 표현되고 응집은 고-액상 분리공정과 Photodynamic therapy에서 중요하게 활용되고 있다. 따라서 입자가 서로 접근될 때 콜로이드 입자들의 상호작용을 LIF와 응집효과로 분석하였다. 우리는 레이저 광원에서 검출기까지 거리의 함수에 의해 in vitro 시료의 산란과 형광 스펙트라를 측정하였다. 산란계수 ${\mu}_s$는 산란체의 입자가 증가함에 크게 나타났다. 그리하여 purple membrane vesicle과 ${\beta}$-carotene의 혼합물의 매질에서 광원에서 검출기에 의한 거리에 대한 측정된 값(I, ${\delta}$)이 거리가 가까워짐에 따라 크게 나타났다.

• Bulletin of the Korean Chemical Society
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• 제27권12호
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• pp.2002-2010
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• 2006

This study examined the quenching of ofloxacin (OFL) and flumequine (FLU) fluorescence by $Cuj^{2+}$, $Ni^{2+}$, $Co^{2+}$ and $Mn^{2+}$ in an aqueous solution. The change in the fluorescence intensity and lifetime was measured at various temperatures as a function of the quencher concentration. According to the Stern-Volmer plots, the fluorescence emission was quenched by both collisions (dynamic quenching) and complex formation (static quenching) with the same quencher but the effect of static quenching was larger than that of dynamic quenching. Large static and dynamic quenching constants for both OFL and FLU support significant ion-dipole and orbital-orbital interactions between fluorophore and quencher. For both molecules, the static and dynamic quenching constants by $Cu^{2+}$ were the largest among all the metal quenchers examined in this study. In addition, both the static and dynamic quenching mechanisms by $Cu^{2+}$ were somewhat different from the quenching caused by other metals. Between $Ni^{2+}$ and FLU, a different form of chemical interaction was observed compared with the interaction by other metals. The change in the absorption spectra as a result of the addition of a quencher provided information on static quenching. With all these metals, the static quenching constant of FLU was larger than those of OFL. The fluorescence of OFL was quite insensitive to both the dynamic and static quenching compared with FLU. This property of OFL can be explained by the twisted intramolecular charge transfer in the excited state.

• Bulletin of the Korean Chemical Society
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• 제27권11호
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• pp.1801-1808
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• 2006

The interaction between whey carrier protein $\beta$-lactoglobulin type A and B (BLG-A and -B) and 2,2'-bipyridin n-hexyl dithiocarbamato Pd(II) nitrate (BPHDC-Pd(II)), a new heavy metal complex designed for anticancer property, was investigated by fluorescence spectroscopy combined with chemometry and circular dichroism (CD) techniques. A strong fluorescence quenching reaction of BPHDC-Pd(II) to BLG-A and -B was observed. Hence, BPHDC-Pd(II) complex can be bound to both BLG-A and -B, and quench the fluorescence spectra of the proteins. The quenching constant was determined using the modified Stern-Volmer equation. The binding parameters were evaluated by fluorescence quenching method. The results of binding study provided evidences presence of two and three sets of binding sites on the BLG-B and -A, respectively, for BPHDC-Pd(II) complex. Using fluorescence spectroscopy and chemometry, the ability of BLG-A and -B to form an intermediate upon interaction with BPHDC-Pd(II) complex was assessed. CD studies displayed that under influence of different concentrations of BPHDC-Pd(II) complex, the regular secondary structure of BLG-B had no significant changes, whereas for BLG-A a transition from $\alpha$-helix to $\beta$-structure was appeared. The results for both of BLG-A and -B displayed that BPHDC-Pd(II) complex can induce a conformational transition from the native form to an intermediate state with a slightly opened conformation, which is detectable with chemometry analyses.

• 생명과학회지
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• 제15권6호
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• pp.935-940
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• 2005

Coumarine이 부착된 인산결합 단백질 (PBP-MDCC)의 형광변화가 뉴클레오사이드 삼인산 가수분해과정에서 배출된 무기 인산의 양을 측정하기 위해 관찰되었다. PBP-MDCC 정제후, 형광 방출 스펙트럼은 형광세기가 PBP-MDCC의 몰비을로 약 $70\%$까지 직선형태로 증가하는 것을 보였다. 형광 신호와 인산 기준물질과의 상호관계 측정이 인산 농도-형광세기 표준곡선을 구하기 위하여 stopped-flow 기구에서 행하여졌다. dTTP 가수분해로 부터 나오는 에너지를 이용하여 이중나선 DNA를 풀어주는 단백질인 T7박테리오파지 나선효소를 dPTT라 반응 시켰을 때, 형광변화를 배출된 인산의 양으로 전환할 수 있었다. 인산 배출 결과는 단일가닥 Ml3 DNA가 T7나선 효소에 의한 dTTP가수분해반응을 여러배 증가시키는 것을 보인다. 뉴클레오타이드 삼인산 가수분해 반응에 있어서 종말점 분석 대신에, PBP-MDCC에 의한 연속적인 인산 배출 분석이 배출된 인산을 측정하는데 있어서 쉽고 편리한 방법임을 보였다.

• 한국물환경학회지
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• 제38권2호
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• pp.72-81
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• 2022

Numerous studies have investigated the occurrence and fate of microplastics in the environment; however, only limited effort has been devoted to exploring the characteristics of dissolved organic matter (DOM) leached from microplastics. In microplastic (MP)-contaminated environment, MPs are typically mixed with naturally-occurring particles, which interferes with their detection in the environment. Thus, it is necessary to distinguish between the DOM leached from MPs and those leached from natural particles and also to characterize their properties. This study investigated DOM leaching behavior from MPs (polystyrene: PS, polyvinylchloride: PVC) and natural particulates (forest soil: FS, litter leaves: LL) under light, which is considered one of the main weathering processes that affect MPs in the environment. The leached DOM concentrations and fluorescence characteristics were compared under dark versus light conditions. Regardless of the origins, UV light promoted DOM release from all the particulates. More DOM was released from natural particles than from MPs under both conditions. However, the effect of promoting DOM release by UV was more pronounced for MPs than for natural particles. It was observed from fluorescence spectra that the intensity of the humic-like region was substantially reduced when MP-derived DOM was exposed to UV light, whereas the change of intensity was very little for natural particles. Under light conditions, the ratio of protein-like to humic-like fluorescence of MP-derived DOM was higher than that of DOM from natural particles. This study implies that a substantial amount of DOM could be leached from MPs even in MP-polluted environment under UV irradiation. Protein/humic fluorescence ratio could be utilized as a fast probing indicator to separate the two sources of particles under light.

• Macromolecular Research
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• 제12권5호
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• pp.501-506
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• 2004

We have investigated the spectral properties of DNA, including its electric absorption, circular and linear dichroism (CD and LD), and fluorescence emission, in the DNA-linear polyethyleneimine (LPEI) and DNA-branched polyethyleneimine (BPEI) complexes at various polymer concentrations. The spectral properties of both complexes are similar. We observed a relatively moderate change in the absorption and CD spectra at low amine/DNA phosphate (NIP) ratios (< 0.5), followed by a drastic collapse within the N/P range from 0.8 and 1.0. The absorption and CD spectra recovered as the N/P ratio increased to ca. 1.2. In contrast, the LD and emission of ethidium intercalated between the DNA bases decreased almost linearly at N/P ratios between 0.0 and 1.0. These spectra never recovered at higher N/P ratios. We believe that the moderate changes in the spectrum at low N/P ratios occurred because of electrostatic interactions between DNA and BPEI, while the collapsed spectra at N/P ratios between 0.5 and 1.5 occurred because of condensation/aggregation of the DNA. Considering the structure of the polymers, we suggest that the secondary amino group of LPEI and all three amino groups of BPEI are equally involved in DNA condensation.

• 한국세라믹학회지
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• 제52권2호
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• pp.165-170
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• 2015

We employed the high-pressure high temperature (HPHT) process to enhance the colors of natural sapphires to obtain a vivid blue. First, we analyze the content of the coloring agent $Fe_2O_3$ using the wavelength dispersive X-ray fluorescence (WD-XRF) method. The HPHT procedure operates under 1 GPa at various temperatures of 1700, 1750, and $1800^{\circ}C$ for 5 minutes using a cubic press. We determine the color changes using the optical microscopic images, UV-VIS near-infrared (NIR) spectra, micro-Raman spectra, and Fourier transform-infrared (FT-IR) spectra for all sapphire samples before and after the treatment. The optical microscopic results indicate that the HPHT process can enhance the sapphire color to a vivid blue at temperatures above $1750^{\circ}C$. The UV-VIS-NIR spectra identify the color changes explicitly and quantitatively through providing the Lab color scales and color differences. Both results demonstrate that the colors of natural sapphires can be enhanced to a vivid blue using the HPHT process above $1750^{\circ}C$ under 1 GPa for 5 minutes.

• Journal of Photoscience
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• 제9권2호
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• pp.512-514
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• 2002

S-aminolevulinic acid (ALA) is a new kind drug used in photodynamic therapy. ALA-PDT have successfully used in superficial malignancies and some skin diseases. Here the effects of ALA-PDT were studied on leukemia cells and hepatoma cells to explore the application on different kind cancers. It was found from the fluorescence emission spectra, that after ALA incubation the sensitizer - protoporphyrin IX (PpIX) was endogenously produced in both leukemia and hepatoma cells. The fluorescence images showed that the PpIX distribute in cytoplasm. However the efficiency of ALA photodynamic inactivation to two cell lines was different. The leukemia cells were more sensitive for ALA-PDT than hepatoma cells, revealing that the ALA-PDT effect is cell line dependent. However by using ALA-Hexyl ester (He-ALA) instead of ALA, the cell photo-inactivation was improved. The PDT efficiency of He-ALA was 10 times high than that of ALA, showing He-ALA is a very promising drug in ALA-PDT.

• 천문학논총
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• 제12권1호
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• pp.85-98
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• 1997

The A-X (0-0) band of CS, which appears in high dispersion IUE spectra of comets Halley (1982i) and Wilson (19861), has been investigated in detail. We developed models, which include fluorescence and collisional processes We found that in order to account for the observed emission band precisely, IUE tracking errors should be included in line shape calculations it has been found that rotational excitation by electrons is a dominant process in determining populations of rotational ground states. We derived an electron density of $2.0\times10^4/cm^3$ at several thousand kilometers from the comet Wilson's nucleus by examining collisional influence on the CS band structure. We presented a band model for the 0-0 band of $C^{34}S$ and discussed the detectability of $^{34}S$ spectroscopically.