• 폴리머
• /
• 제29권2호
• /
• pp.107-121
• /
• 2005

전기인광소자(electrophosphorescent light emitting diodes)의 경우 인광염료내에 있는 중금속에 의해 효과적인 전자 스핀-궤도 결합(spin-orbit coupling)이 가능하며, 이로 인해 일중항 여기자뿐만 아니라 삼중항 여기자로부터 발광이 가능하므로 이론적으로 $100\%$ 내부발광효율을 얻을 수 있다. 본 논문에서는 지난 몇 년 동안 본 연구실에서 진행한 고분자 호스트를 사용한 고분자 전기인광소자의 특성 및 에너지 전이 메커니즘에 대하여 기술하였다. 또한 고분자 전기인광소자에서의 상분리 및 응집현상이 고분자 호스트와 게스트인 인광염료간의 에너지 전이와 소자 특성에 미치는 영향을 규명하였다. 마지막으로 인광염료의 리간드에 치환체 도입 및 리간드 변화에 따른 전이금속화합물의 광학적, 전기적 특성 변화에 대하여 연구하였다.

• Journal of Microbiology and Biotechnology
• /
• 제24권8호
• /
• pp.1034-1043
• /
• 2014

This study determined the effect of light intensity and photoperiod on the dry cell weight and total amount of carotenoids in four isolates of purple non-sulfur bacteria obtained from shaded and exposed microhabitats of a mangrove ecosystem in Kota Kinabalu, Sabah, Malaysia. The initial isolation of the bacteria was carried out using synthetic 112 medium under anaerobic conditions (2.5 klx) at $30{\pm}2^{\circ}C$. On the basis of colony appearance, cell morphology, gram staining, motility test, and 16S rRNA gene sequencing analyses, all four bacteria were identified as Afifella marina. One of the bacterial isolates, designated as Af. marina strain ME, which was extracted from an exposed mud habitat within the mangrove ecosystem, showed the highest yield in dry cell weight ($4.32{\pm}0.03g/l$) as well as total carotenoids ($0.783{\pm}0.002mg/g$ dry cell weight). These values were significantly higher than those for dry cell weight ($3.77{\pm}0.02g/l$) and total carotenoid content ($0.706{\pm}0.008mg/g$) produced by the isolates from shaded habitats. Further analysis of the effect of 10 levels of light intensity on the growth characteristics of Af. marina strain ME showed that the optimum production of dry cell weight and total carotenoids was achieved at different light intensities and incubation periods. The bacterium produced the highest dry cell weight of 4.98 g/l at 3 klx in 72 h incubation, but the carotenoid production of 0.783 mg/g was achieved at 2.5 klx in 48 h incubation. Subsequent analysis of the effect of photoperiod on the production of dry cell weight and total carotenoids at optimum light intensities (3 and 2.5 klx, respectively) revealed that 18 and 24 h were the optimum photoperiods for the production of dry cell weight and total carotenoids, respectively. The unique growth characteristics of the Af. marina strain ME can be exploited for biotechnology applications.

• 한국작물학회:학술대회논문집
• /
• 한국작물학회 2017년도 9th Asian Crop Science Association conference
• /
• pp.213-213
• /
• 2017

High quality seed of proso millet that has high germination percentage, germination speed, and uniformity demanded to increases rates of mechanization in cereal crop cultivation. In order to improve germination characteristics, proso millet seeds were treated with red light, ultrasonication and liquid smoke (LS) solution that generated from hickory wood. All treatments were performed in seed priming solution with 100mM $NH_4NO_3$ at $15^{\circ}C$ for 24hrs under aeration condition. Seeds were exposed under light intensity of 2000 lux for 15m, 30m, 60m, and 120m in priming solution. Ultrasonic treatment was performed at 60%, 80%, and 100% intensity of 21.6 KHz for 5m, 10m, and 20m in priming solution. For LS treatment seed were soaked in 0%, 0.5%, 1.0%, 5.0% and 10.0% of diluted solution with $dH_2O$ or 100mM $NH_4NO_3$ solution. The effect of seed treatment was evaluated with germination percentage (GP), mean germination time (MGT), germination index (GI), germination rate (GR), Germination uniformity (GU) and heath seed percentage (HS). Our results demonstrate that red light (15min) or ultrasonication (21.6kHz, 5min) treatment improved MGT, GI, GR, and GU comparing to untreated control. Importantly, we show that LS treatments have significant effect on the health seedling and germination characteristics. Proso millet seeds that treated with 5% LS solution for 24hrs improves HS up to 97% that similar results obtained in 100mM $NH_4NO_3$ priming for 24hrs. The combined treatment with LS solution and 100mM $NH_4NO_3$ priming were not effective in all treatments. Our results demonstrate that treating seeds with LS or 100mM $NH_4NO_3$ priming or ultrasonication improves germination characteristics. The methods described here will help advance research using this species by increasing the germination performance at which successive seed pellet process.

• Journal of Photoscience
• /
• 제1권2호
• /
• pp.83-88
• /
• 1994

The synergic effect of iron plus blue light on the peroxidation of membrane lipid was investigated, using liposomes made of phospholipid. While strong irradiation did not affect Fe$^{+2}$-promoted lipid peroxidation that turned out to be O$_2$-dependent, ferric iron in bright light exerted a pronounced effect on the initiation of lipid peroxidation: this combined action of light and Fe$^{+3}$ on liposomal membranes was apparently independent of O$_2$. When liposomal samples containing Fe$^{+3}$ were subjected to irradiation, some portions of Fe$^{+3}$ were converted into Fe$^{+2}$. The extent of the Fe$^{+3}$-Fe$^{+2}$ conversion increased with increasing time of irradiation, which resembled the dependence of Fe$^{+3}$-promoted lipid peroxidation on irradiation. Further, it was observed that the effect of irradiation in liposomal samples containing Fe$^{+2}$ was strikingly mimicked by that of Fe$^{+2}$ addition to the same samples. The obligatory requirement of a suitable Fe$^{+3}$/Fe$^{+2}$ ratio for the genesis of iron-dependent lipid peroxidation, a controversial proposition, was also confirmed by the observation that lipid peroxidation was substantially enhanced by the addition of a mixture of Fe$^{+3}$ and Fe$^{+2}$, as compared to the addition of Fe$^{+3}$ or Fe$^{+2}$ alone. The results obtained in this study not only suggest that light acts as an effector for initiating lipid peroxidation, when Fe$^{+3}$ is present in membrane systems, but also imply that any chemical or physical factor that influences the redox states of iron in membranes can play a role in lipid peroxidation reactions.

• The Journal of Korean Physical Therapy
• /
• 제12권1호
• /
• pp.41-47
• /
• 2000

BACKGROUND AND PURPOSE. The purpose of this study is to investigate the effect of the disturbed vision on the gait distance parameters on the healthy young population. SUBJECTS. Twenty four healthy college aged individuals are randomly assigned to both a condition with a strobe light and the other condition without a strobe light. METHODS. The instrumentation used for gait analysis is the GaitRite electronic walkway system with a personal IBM computer. The examiner naked all the subjects to walk 6 times on the gait mat without the strobe light and. 6 times on the mat with the strobe light. The first 4 trials were practice and the last two trials were recorded in both conditions. The gait parameters analyzed were as follows : velocity, cadence, step length, and heel to heel base of support. RESULTS. Paired samples t-test used for this study did not found any significant differences between the two conditions because the p-values that were analyzed on the experiment were Utter than 0.05. The gait parameters that were analyzed included cadence, velocity, left and right heel to heel base of support, and left and right step length. DISCUSSION AND CONCLUSION. Based on this population, the condition of disturbed vision via the effect of the strobe light was not significantly challenging to compromise the body's sensory systems. However, in the elderly population, these systems can undergo age related changes. Visual changes rapidly decline in people 60 to 80 years of age and changes in the vestibular system include $20-40\%$ reduction in hair cells.

• Restorative Dentistry and Endodontics
• /
• 제12권1호
• /
• pp.85-93
• /
• 1986

The purpose of this study was to investigate the curing effect of visible light through tooth substance, 0.5mm, 1.0mm thickness of enamel and dentin were prepared. Experimental specimen were made by Bisfil M & Silux packing into cylindrical brass mold 6.0mm in diameter, 2.0mm and 3.0mm, in height. All specimen were irradiated by visible light (Grip type) model No. SDL-50 Shofu Co.) for 30 seconds through tooth substance. Experimental groups were classified into enamel group (group 1) and dentin group (group 2) according to the thickness of tooth materials and then were divided into 2 subgroups (0.5mm group and 1.0mm group). In experimental groups, visible light irradiated to the specimen through either 0.5mm in thick or 1.0mm in think of tooth material. In Control group specimen were prepared by direct irradiation on the specimen surface of visible light without through tooth substance. The hardness was measured with a Barcol hardness tester (Barber-Colman Co. U.S.A.) for each prepared specimen. The results were as follows: 1. In control group, there were higher hardness values than those of in experimental group. 2. In experimental groups, 0.5mm groups had higher hardness values than 1.0mm groups did. 3. The hardness value at top surface of the specimen were higher than the hardness of bottom surface in each group. 4. Bisfil M had higher hardness values than Silux. 5. In all specimen of 3.0mm height polymerization effect was not occurred at bottom surface except Bisfil M in control group.

• 대한소아치과학회지
• /
• 제25권1호
• /
• pp.62-75
• /
• 1998

The main purpose of this study was to compare the anticariogenecity of glass ionomer restorative material polymerized by argon laser versus visible light, The results from the present study can be summarized as follows; 1. Under the polarized light microscope, the specimens of laser-cured group showed the shallower lesion body than that of visible-light cured group, both in the stage of lesion initiation and progression. 2. Glass ionomer material cured by visible light showed shallower body of lesion than that of composite resin cured by argon laser at the stage of lesion progression(p<0.05). It was suggested fluoride released from the glass ionomer might have the additive anticariogenic effect. 3. Statistical difference between groups on depth of lesion body was evident after lesion progression (p<0.05). It was suggested that anticariogenic effect by argon laser was more effective at the stage of lesion progression than the lesion initiation. 4. The increment of lesion body during progression was highest in group IV (p<0.05). 5. Based upon the above-mentioned results of this study, it can be concluded that the advantage of anticariogenic effect and short curing time of argon laser in glass ionomer polymerization should be considered in children and adolescents whose caries activity is relatively higher.

• 한국재료학회지
• /
• 제28권11호
• /
• pp.680-684
• /
• 2018

We investigate the effect of light intensity and wavelength of a solar cell device using photoconductive atomic force microscopy(PC-AFM). A $POCl_3$ diffusion doping process is used to produce a p-n junction solar cell device based on a polySi wafer, and the electrical properties of prepared solar cells are measured using a solar cell simulator system. The measured open circuit voltage($V_{oc}$) is 0.59 V and the short circuit current($I_{sc}$) is 48.5 mA. Moreover, the values of the fill factors and efficiencies of the devices are 0.7 and approximately 13.6 %, respectively. In addition, PC-AFM, a recent notable method for nano-scale characterization of photovoltaic elements, is used for direct measurements of photoelectric characteristics in limited areas instead of large areas. The effects of changes in the intensity and wavelength of light shining on the element on the photoelectric characteristics are observed. Results obtained through PC-AFM are compared with the electric/optical characteristics data obtained through a solar simulator. The voltage($V_{PC-AFM}$) at which the current is 0 A in the I-V characteristic curves increases sharply up to $18W/m^2$, peaking and slowly falling as light intensity increases. Here, $V_{PC-AFM}$ at $18W/m^2$ is 0.29 V, which corresponds to 59 % of the average $V_{oc}$ value, as measured with the solar simulator. Furthermore, while the light wavelength increases from 300 nm to 1,100 nm, the external quantum efficiency(EQE) and results from PC-AFM show similar trends at the macro scale but reveal different results in several sections, indicating the need for detailed analysis and improvement in the future.

• Macromolecular Research
• /
• 제11권3호
• /
• pp.133-145
• /
• 2003

We have developed novel lanthanide-cored supramolecular systems with highly efficient light-harvesting dendritic arrays for integrated planar waveguide-typed amplifiers. Er$^{3+}$ ions were encapsulated by the supramolecular ligands, such as porphyrins and macrobicyclics. The supramolecular ligands have been designed and synthesized to provide enough coordination sites for the formation of stable Er(III)-chelated complexes. For getting a higher optical amplification gain, also, the energy levels of the supramolecular ligands were tailored to maintain the effective energy transfer process from supramolecular ligands to erbium(III) ions. Furthermore, to maximize the light-harvesting effect, new aryl ether-functionalized dendrons as photon antennas have been incorporated into lanthanide-cored supramolecular systems. In this paper, molecular design, synthesis and luminescent properties of novel lanthanide-cored integrated supramolecular systems with highly efficient light-harvesting dendritic arrays will be discussed.d.

• 한국환경과학회지
• /
• 제1권2호
• /
• pp.81.1-86
• /
• 1992

The amounts of ascorbic acid in chloroplasts treated with light and light+paraquat (PQ) were reduced by 81 and 82% of initial level, respectively at 24 hr at incubation. And those treated with dark and dark+PQ were decreased by W and 55% of the original level, respectively. Malondialdehyde (MDA) contents at 24 hr of dark and dark+PQ treatment were increased by 6 and 31% of the initial level, respectively. When chloroplasts were treated with light and light+PQ, MDA contents after 24 hr were increased by 88 and 146% of the initial level, respectively. SOD activities treated with light and light+PQ were increased by 10 and 20% of the initial level, respectively for 3 hr and thereafter reduced by 46 and 49% of the original level, respectively at 24 hr. However, the SOD activities treated with dark and dark+PQ were decreased by 37 and 30% of the initial level, respectively. It is considered that PQ triggers the oxidation of ascorbic acid, the induction of lipid peroxidation and the inactivation of SOD under light so that PQ has inhibitors effect on the pathway of plant metabolism. Key word: ascorbic acid, malondialdehyde, superoxide dismutase, paraquat, lipid peroxidation.