• Proceedings of the PSK Conference
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• 2003.04a
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• pp.231.1-231.1
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• 2003

Ultraviolet (UV) irradiation is well known to cause human skin aging and skin cancer through activation of matrix metalloproteinases (MMPs) which are responsible for the degradation of collagen, an extracellular matrix component. However, the molecular mechanisms of UV-induced MMP expression are yet to be defined. In this study, we investigated signaling molecules involved in UV-induced MMP expression in HaCaT human keratinocytes. (omitted)

• Journal of Photoscience
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• v.9 no.2
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• pp.442-444
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• 2002

Seedlings of spinach (Spinacia oleracea L. "King of Denmark" and "Minsterland") were grown with or without supplemental UV-B under field conditions for five or nine days when their fifth or sixth leaves were expanding. Except two leaves which were just expanded and expanding, all other leaves of each seedling were removed before tested. One of these two leaves was exposed to UV-B irradiation and the other leaf was covered with lumiror film (no transmission below 320 nm) to prevent it from UV-B exposure. l,l-diphenyl-2-picrylhydrazyl scavenging activities (antioxidative activity) in leaves without covers were increased according to UV-B doses they were exposed to. And removal of UV-B exposure with lumiror decreased foliage antioxidative activities. This increase or decrease of activities in leaves did not dependent on the UV-B doses their paired leaves were exposed to in both two cultivars. The results demonstrated that spinach foliage antioxidants induced by UV-B exposure were not transported into another leaf.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.7
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• pp.604-610
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• 2004

Ultraviolet-nanoimprint lithography (UV-NIL) is a promising method for cost-effectively defining nanoscale structures at room temperature and low pressure. Since the resolution of transferred nanostructures depends strongly upon that of nanostamps, the nanostamp fabrication technology is a key technology to UV-NIL. In this paper, a $5\times5\times0.09$ in. quartz stamp whose critical dimension is 377 nm was fabricated using the etching process in which a Cr film was employed as a hard mask for transferring nanostructures onto the quartz plate. To effectively apply the fabricated 5-in. stamp to UV-NIL on a 4-in. Si wafer, we have proposed a new UV-NIL process using a multi-dispensing method as a way to supply resist on a wafer. Experiments have shown that the multi-dispensing method can enable UV-NIL using a large-area stamp.

• Analytical Science and Technology
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• v.28 no.2
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• pp.112-116
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• 2015

Extraction of quaternary ammonium compounds (choline and betaine) from plant samples (spinach) using ion exchange resin (AG1, OH⁻ form) is a very simple and inexpensive approach. However, it is very hard to determine amounts of choline and betaine simultaneously using high-performance liquid chromatography-ultraviolet (HPLC-UV) detection. Unlike choline, betaine has low molar absorptivity in UV-visible (UV-Vis) region, which makes it difficult to carry out UV-Vis detection of betaine. The mixture of quaternary ammonium compounds (choline and betaine) was derivatized using 2-bromo acetophenone as a derivatizing agent. As a result, choline did not react with the derivatizing agent, whereas betaine formed a betaine derivative. This betaine derivative exhibited detectable UV absorption with baseline separation between choline and the betaine derivative. Thus, with this method, choline and betaine can be determined simultaneously by using the HPLCUV method through one-step derivatization, which is an easy, sensitive, and reliable method.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.34.1-34.1
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• 2011

태양전지 모듈의 25년 이상 보증을 위해 태양전지 모듈을 구성하는 부품 소재의 장기 열화메카니즘 연구가 중요시되고 있다. 그 중 봉지제(Encapsulation) 부품으로 적용되고 있는 태양전지 모듈용 에틸렌 비닐 아세테이트(Ethylene Vinyl Acetate, EVA)는 셀을 보호하는 폴리머 부품으로 장기 열화특성 연구가 중요하다. 따라서 EVA를 가속열화하여 25년 보증 내구성을 보유하고 있는지 연구가 필요하다. 본 연구에서는 태양전지 모듈을 구성하는 재료 중 외부환경에 민감한 폴리머 소재인 EVA의 Ultraviolet (UV), 온도 두 환경스트레스 조건을 적용한 가속수명시험을 수행하고 장기 열화메카니즘을 분석하였다. 시험에 앞서 UV/온도 가속수명시험을 설계하였다. UV/온도 가속조건을 설정하기 위해 실환경에서 변화하는 UV와 온도를 일정한 값으로 나타낼 수 있는 유효 UV (Effective UV)와 유효 온도(Effective temperature)를 도출하였다. 이를 통해 UV/온도 가속조건을 설정하였고 1년 및 25년 동안 EVA에 인가되는 stress와 동일한 양을 인가할 수 있는 시험시간을 결정하였다.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1847-1850
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• 2008

The process conditions during ultraviolet nanoimprint lithography (UV-NIL) process such as temperature, stamping pressure, UV irradiation, etc. are effective factors for successful imprinting of complex and fine patterns. In this study, the effects of aluminum mold on the thermal characteristics of UV-NIL process were investigated through imprinting experiments and numerical simulations. The temperature of polymer resin on mold was measured to study thermal characteristics during UV curing. From the experimental and numerical results, the importance of curing reaction control for UV-NIL process was discussed for deformation characteristics.

• Ceramist
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• v.22 no.1
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• pp.27-35
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• 2019

Research on ultraviolet (UV) light detection has attracted considerable attention from scientific researchers in related fields. It can be said that it is a very important time to accurately monitor the UV irradiation amount according to the wavelength region in real time. The oxide is very diverse in its kind and has the advantage of being able to efficiently control the band gap through band gap engineering. In addition, it is very stable in response to heat and atmospheric oxygen when UV is absorbed. Also, there is a known method that can effectively manufacture oxide nanoparticles and nanorods through various synthesis methods, and researches for improving the sensitivity of UV sensors have been carried out using this method. In this paper, we introduce the materials that can be used as UV sensors among various wide band oxide materials, and review the results of researches of various UV sensors using nano materials.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.2
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• pp.245-252
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• 2011

The combined effects of 10 kJ/$m^2$ ultraviolet-C (UV-C) with 50 ppm aqueous chlorine dioxide ($ClO_2$) on the qualities of red chicory and pak choi were examined. After the treatment, the samples were stored at $4{\pm}1^{\circ}C$ for 7 days. The combined treatment of $ClO_2$/UV-C reduced the initial populations of total aerobic bacteria in the red chicory and pak choi by 2.64 and 2.55 log CFU/g, respectively, compared to those of the control. Also, the populations of yeast and molds in the red chicory and pak choi by combined treatment were reduced by 2.41 and 2.00 log CFU/g, respectively. In addition, after 7 days of storage the total aerobic bacteria populations in the red chicory and pak choi were reduced to 3.71 and 3.93 log CFU/g, compared to 6.31 and 6.62 log CFU/g for the control, resulting in a significant decrease. Hunter L, a, and b values of red chicory and pak choi were not significantly different among the treatments. Non-thermal treatment caused a negligible change in sensory evaluation. These results suggest that the combined treatment of 50 ppm $ClO_2$ with 10 kJ/$m^2$ UV-C can be useful for maintaining the qualities of red chicory and pak choi.

• Animal cells and systems
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• v.5 no.1
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• pp.77-83
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• 2001

The present study was conducted to elucidate whether the expression level of poly(ADP-ribose) polymerase (PARP) is related to the ultraviolet radiation (UV)-induced apoptosis. After treatment of the mammalian cell lines HeLa S3 and Chinese hamster ovary (CHO) with 50 J/m2 UV, induction of apoptosis was determined by several means during 24 h post-incubation. Incidence of apoptosis was much lower in CHO than HeLa S3 cells based on the percentage of apoptotic cells in terms of morphological changes in nucleus or direct counting of viable cells and qualitative or quantitative DNA fragmentation. Interestingly, when the expression level of PARP was measured by western blotting, the amounts of PARP that was retained at each time point inversely correlated with the incidences of apoptosis in these cells. Concomitant with generation of the 85 kDa fragment, 116 kDa PARP disappeared in HeLa S3 within 6 h after UV treatment, whereas a fair amounts of 116 kDa band was still retained in CHO cells at 36 h post-incubation. This inverse relationship was also observed in the adaptive response system, in which cells weve treated with a high dose of UV after pretreatment with a low dose. As expected, typical adaptive responses appeared in CHO cells but not in HeLa cells, showing greater cell viability and lesser DNA fragmentation. During the adaptive response in CHO cells, PARP was expressed at much higher level compared to the single, high dose-treated cells. Interestingly, even though PARP was induced at 6 h post-incubation In both cell types, its expression was more prominent in CHO cells. Thus, our data indicate that the retained level of intact PARP against UV damage inversely correlates with incidence of apoptosis in mammalian cells, and also suggest that a machinery to protect the PARP degradation against UV damage exists in CHO but not in HeLa S3 cells.

• Journal of Ginseng Research
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• v.44 no.2
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• pp.274-281
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• 2020

Background: Ultraviolet (UV) goes through the epidermis and promotes release of inflammatory cytokines in keratinocytes. Granulocyte-macrophage colony-stimulating factor (GM-CSF), one of the keratinocyte-derived cytokines, regulates proliferation and differentiation of melanocytes. Extracellular signal-regulated kinase (ERK1/2) and protein kinase C (PKC) signaling pathways regulate expression of GM-CSF. Based on these results, we found that ginsenoside Rh3 prevented GM-CSF production and release in UV-B-exposed SP-1 keratinocytes and that this inhibitory effect resulted from the reduction of PKCδ and ERK phosphorylation. Methods: We investigated the mechanism by which ginsenoside Rh3 from Panax ginseng inhibited GM-CSF release from UV-B-irradiated keratinocytes. Results: Treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) or UV-B induced release of GM-CSF in the SP-1 keratinocytes. To elucidate whether the change in GM-CSF expression could be related to PKC signaling, the cells were pretreated with H7, an inhibitor of PKC, and irradiated with UV-B. GM-CSF was decreased by H7 in a dose-dependent manner. When we analyzed which ginsenosides repressed GM-CSF expression among 15 ginsenosides, ginsenoside Rh3 showed the largest decline to 40% of GM-CSF expression in enzyme-linked immunosorbent assay. Western blot analysis showed that TPA enhanced the phosphorylation of PKCδ and ERK in the keratinocytes. When we examined the effect of ginsenoside Rh3, we identified that ginsenoside Rh3 inhibited the TPA-induced phosphorylation levels of PKCδ and ERK. Conclusion: In summary, we found that ginsenoside Rh3 impeded UV-B-induced GM-CSF production through repression of PKCδ and ERK phosphorylation in SP-1 keratinocytes.