• 한국치위생학회지
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• 제14권4호
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• pp.585-591
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• 2014

Objectives : The purpose of this study was to investigate of the color change, tooth surface and intra-pulpal temperature of tooth bleaching by light activation Methods : Forty-eight extracted bovine teeth were immersed into a tea solution for 24 hours. The specimens were randomly divided into four groups(n=15):(G1) 15% HP + without light activation, (G2) 15% HP + light activation, (G3) 25% HP + without light activation, (G4) 25% HP + light activation. All specimens were bleached for 15 minutes three times. The spectrophotometer (CM-2600d, Konica Minolta, Osaka, Japan) was used including before bleaching, immediately after bleaching, 1 week, 1 and 3 months after the end of bleaching. The temperature rise were measured in the pulpal chamber and tooth surface with a digital thermocouple thermometer(Termopar Digital Multimeter, Tektronix DMM916, USA). Between the tested time points, the specimens were stored in distilled water. The data were analyzed by ANOVA, t-test and Tukey's post hoc test set at 0.05. Results : There was no significant color change by the use of light after the bleaching treatment(p>0.05). The dental bleaching treatments of teeth with 15% HP and 25% HP did not seem to be more effective when light source was used. There was no difference in color stability between groups within three month(p>0.05). There was an increase in tooth surface and pulp temperature, but it was not sufficient to cause damage to the pulp. Conclusions :The use of light activation has no obvious effective impact on the tooth bleaching effect.

• IMMUNE NETWORK
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• 제4권2호
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• pp.116-122
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• 2004

Background: LIGHT (TNFSF14) is a member of tumor necrosis factor superfamily and is the ligand for TR2 (TNFRSF14/HVEM). LIGHT is known to have proinflammatory roles in atherosclerosis. Methods: To find out the expression pattern of LIGHT in atherosclerotic plaques, immunohistochemical analysis was performed on human carotid atherosclerotic plaque specimens. LIGHT induced atherogenic events using human monocytic cell line THP-1 were also investigated. Results: Immunohistochemical analysis revealed expression of LIGHT and TR2 in foam cell rich regions in the atherosclerotic plaques. Double immunohistochemical analysis further confirmed the expression of LIGHT in foam cells. Stimulation of THP-1 cells, which express TR2, with either recombinant LIGHT or immobilized anti-TR2 monoclonal antibody induced interleukin-8 and matrix metalloproteinase(MMP)-9. Electrophoretic mobility shift assay demonstrated that LIGHT induces nuclear localization of transcription factor, nuclear factor $(NF)-{\kappa}B$. LIGHT induced activation of MMP-9 is mediated by $NF-{\kappa}B$, since treatment of THP-1 cells with the $NF-{\kappa}B$ inhibitor PDTC (pyrrolidine dithiocarbamate) completely blocked the activation of MMP-9. Conclusion: These data indicate that LIGHT is expressed in foam cells in atherosclerotic plaques and is involved in atherogenesis through activation of pro-atherogenic cytokine IL-8 and destabilization of plaque by inducing matrix degrading enzyme.

• Molecules and Cells
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• 제38권7호
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• pp.651-656
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• 2015

Plant growth and development are coordinately orchestrated by environmental cues and phytohormones. Light acts as a key environmental factor for fundamental plant growth and physiology through photosensory phytochromes and underlying molecular mechanisms. Although phytochromes are known to possess serine/threonine protein kinase activities, whether they trigger a signal transduction pathway via an intracellular protein kinase network remains unknown. In analyses of mitogen-activated protein kinase kinase (MAPKK, also called MKK) mutants, the mkk3 mutant has shown both a hypersensitive response in plant hormone gibberellin (GA) and a less sensitive response in red light signaling. Surprisingly, light-induced MAPK activation in wild-type (WT) seedlings and constitutive MAPK phosphorylation in dark-grown mkk3 mutant seedlings have also been found, respectively. Therefore, this study suggests that MKK3 acts in negative regulation in darkness and in light-induced MAPK activation during dark-light transition.

• 한국컴퓨터정보학회논문지
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• 제21권12호
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• pp.11-18
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• 2016

Magnetic resonance image (MRI) is widely used in brain research field and medical image. Especially, non-invasive brain activation acquired image technique, which is functional magnetic resonance image (fMRI) is used in brain study. In this study, we investigate brain activation occurred by LED light stimulation. For investigate of brain activation in experimental small animal, we used high magnetic field 9.4T MRI. Experimental small animal is Balb/c mouse, method of fMRI is using echo planar image (EPI). EPI method spend more less time than any other MRI method. For this reason, however, EPI data has low contrast. Due to the low contrast, image pre-processing is very hard and inaccuracy. In this study, we planned the study protocol, which is called block design in fMRI research field. The block designed has 8 LED light stimulation session and 8 rest session. All block is consist of 6 EPI images and acquired 1 slice of EPI image is 16 second. During the light session, we occurred LED light stimulation for 1 minutes 36 seconds. During the rest session, we do not occurred light stimulation and remain the light off state for 1 minutes 36 seconds. This session repeat the all over the EPI scan time, so the total spend time of EPI scan has almost 26 minutes. After acquired EPI data, we performed the analysis of this image data. In this study, we analysis of EPI data using statistical parametric map (SPM) software and performed image pre-processing such as realignment, co-registration, normalization, smoothing of EPI data. The pre-processing of fMRI data have to segmented using this software. However this method has 3 different method which is Gaussian nonparametric, warped modulate, and tissue probability map. In this study we performed the this 3 different method and compared how they can change the result of fMRI analysis results. The result of this study show that LED light stimulation was activate superior colliculus region in mouse brain. And the most higher activated value of segmentation method was using tissue probability map. this study may help to improve brain activation study using EPI and SPM analysis.

• 대한치과보철학회지
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• 제52권3호
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• pp.195-201
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• 2014

목적: 본 연구에서는 세 가지 중합 방법에 따른 이원 중합 레진 시멘트의 중합 수축률을 비교하고 광조사가 중합 정도에 미치는 영향에 관하여 알아보고자 하였다. 재료 및 방법: 네 가지 종류의 이원 중합형 레진 시멘트(Smartcem 2, Panavia F 2.0, Clearfil SA Luting, Zirconite)가 사용되었다. 각 재료 당 세가지 서로 다른 중합 방법(자가 중합, 즉시 광중합, 5분 지연 광중합)으로 중합하였으며, 각 방법 당 5개의 시편을 사용하였다. Bonded disk method를 사용하여 $37^{\circ}C$에서 30분간, 시간에 따른 중합 수축률을 측정하였다. 측정값은 일원분산분석과 다중 분석을 위한 Scheff$\acute{e}$ test를 사용하였고, 유의수준은 0.05으로 하였다. 결과: Panavia F 2.0를 제외한 나머지 세 종류의 이원 중합 레진 시멘트들은 지연 광중합 반응에서 가장 높은 중합 수축률을 보였다. Panavia F 2.0의 중합 수축률은 중합 방법간에 통계학적 유의성이 없었다. 중합이 개시된 초기 10분 내에 즉시 혹은 지연 광중합에서 모든 시멘트는 90% 이상의 중합수축을 보였다. 결론: 이원 중합 레진 시멘트의 지연 광중합이 중합 효율을 높인다.

• Journal of Photoscience
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• 제9권2호
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• pp.246-248
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• 2002

Light is a major environmental signal for entrainment of the circadian clock, but little is known about the phototransduction pathway triggered by light-activation of photoreceptive molecule(s) responsible for the phase shift of the clock in vertebrates. The chicken pineal gland and retina contain the autonomous circadian oscillators together with the photic entrainment pathway, and hence they provide useful experimental model for the clock system. We previously demonstrated the expression and light-dependent activation of rod-type transducin $\alpha$-subunit (Gtl$\alpha$) in the chicken pineal gland. It is unlikely, however, that the pineal Gt$_1$$\alpha$ plays a major role in the photic entrainment, because the light-induced phase shift is unaffected by bloking the signaling function of Gt$_1$$\alpha$. Here, we show the expression of G 11 $\alpha$, an $\alpha$-subunit of another heterotrimeric G-protein, in the chicken pineal gland and retina by cDNA cloning, Northern blot and Western blot analyses. GIl$\alpha$-immunoreactivity was colocalized with pinopsin in the chicken pineal cells and it was found predominantly at the outer segments of photoreceptor cells in the retinal sections, suggesting functional coupling of G11 $\alpha$ with opsins in the both the tissues. By coimmunoprecipitation experiments using the retina, we showed the light- and GTP-dependent interaction between rhodopsin and G11 $\alpha$. Upon ectopic expression of a Gq/ 11-coupled receptor in cultured pineal cells, pharmacological (non-photic) activation of endogenous G11 induced phase-dependent phase shifts of the melatonin rhythm in a manner very similar to the effect of light. These results suggested opsin-G11 pathway contributing to the photic entrainment of the circadian clock.

• BMB Reports
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• 제29권6호
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• pp.535-539
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• 1996

The activation of phospholipase D (PLD) catalyzes hydrolysis of phosphatidylcholine (PC) to phosphatidic acid (PA) and choline in plants as well as animals. To determine the presence of PLD in oat cells, we prepared inside-out plasma membrane and cytosolic fractions from oat tissues. PLD activities in both cytosol and plasma membrane were detected by ion chromatography method. The activity of PLD in plasma membrane was dependent upon $Ca^{2+}$ concentration and was heat stable. To investigate whether G-protein couples to PLD, the effects of $GTP{\gamma}S$ and $GDP{\beta}S$ on the PLD activity were measured. PLD activity was dramatically increased 300~400% in the presence of 50 ${\mu}M$ $GTP{\gamma}S$ but not in the presence of 50 ${\mu}M$ $GDP{\beta}S$. These results indicate that G-protein may be involved in regulation of PLD activity. To identify whether PLD is regulated by red light receptor, phytochrome, we irradiated red, far-red, or red/far-red/red light on oat protoplasts. PLD activity has increased 5-fold and 3-fold by treatment with red light and red/far-red/red light, respectively. In contrast, irradiation with far-red light had little or no effect on PLD activity. These results suggest that phytochrome regulates PLD activity through activation of G-protein in oat cells.

• Restorative Dentistry and Endodontics
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• 제44권3호
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• pp.28.1-28.10
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• 2019

Objectives: The aim of this study was to evaluate the influence of different concentrations of nanofillers on the chemical and physical properties of ethanol-solvated and non-solvated dental adhesives. Materials and Methods: Eight experimental adhesives were prepared with different nanofiller concentrations (0, 1, 2, and 4 wt%) and 2 solvent concentrations (0% and 10% ethanol). Several properties of the experimental adhesives were evaluated, such as water sorption and solubility (n = 5, 20 seconds light activation), real-time degree of conversion (DC; n = 3, 20 and 40 seconds light activation), and stability of cohesive strength at 6 months (CS; n = 20, 20 seconds light activation) using the microtensile test. A light-emitting diode (Bluephase 20i, Ivoclar Vivadent) with an average light emittance of $1,200mW/cm^2$ was used. Results: The presence of solvent reduced the DC after 20 seconds of curing, but increased the final DC, water sorption, and solubility of the adhesives. Storage in water reduced the strength of the adhesives. The addition of 1 wt% and 2 wt% nanofillers increased the polymerization rate of the adhesives. Conclusions: The presence of nanofillers and ethanol improved the final DC, although the DC of the solvated adhesives at 20 seconds was lower than that of the non-solvated adhesives. The presence of ethanol reduced the strength of the adhesives and increased their water sorption and solubility. However, nanofillers did not affect the water sorption and strength of the tested adhesives.

• Bulletin of the Korean Chemical Society
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• 제20권9호
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• pp.1010-1016
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• 1999

We synthesized the photoresponsive side chain polymers containing aminonitro azobenzene for studying the effect of temperature on photoinduced birefringence. Four different copolymers were prepared using methacrylate, α-methylstyrene, and itaconate monomer. Photoisomerization was observed under the exposure of UV light using UV-VIS absorption spectroscopy. Reorientation of polar azobenzene molecules induced optical anisotropy under a linearly polarized light at 532 nm. The change of the birefringence was observed with increasing the sample temperature under a continuous irradiation of excitation light. We could estimate the activation energy of molecular motion in thermal and photochemical mode. Besides the effect of glass transition temperature on the activation energy, we focused our interests on the effect of geometrical hindrance of polar azobenzene molecules and cooperative motion of environmental mesogenic molecules in the vicinity of polar azobenzene molecules.

• 마이크로전자및패키징학회지
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• 제28권4호
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• pp.85-89
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• 2021

AlGaN 기반 UV-C 발광다이오드(LEDs)에 전기화학적 전위차 활성화(EPA)에 의한 p-형 활성화를 진행하였다. 높은 저항과 낮은 전도도를 유발하는 중성 Mg-H의 복합체의 수소원자를 EPA를 이용하여 제거하여 p-형 활성화 효율을 높였다. 중성 Mg-H 복합체는 주요 매개 변수인 용액, 전압, 시간에 의해 Mg^-과 H⁺로 분해되며, 2차 이온질량 분광법(SIMS) 분석을 통하여 개선된 정공 캐리어의 농도를 확인할 수 있었다. 이 메커니즘은 결국 내부 양자효율(IQE)의 증가, 광 추출 효율 향상, 역 전류 영역의 누설전류 값 개선, 접합 온도 개선 등을 이루어 결과적으로 UV-C LED의 수명을 향상시켰다. 체계적인 분석을 위해 SIMS, Etamax IQE 시스템, 적분구, 전류-전압(I-V) 측정 등을 사용하였으며, 그 결과를 기존의 N₂-열 처리 방법과 비교 평가하였다.