• Korean Journal of Food Science and Technology
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• v.33 no.6
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• pp.693-699
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• 2001

ChlorophyII destruction by irradiation in linoleic acid in methanol system was studied. ChlorophyII b standard (3 ppm) was added into methanol solution containing 1% of linoleic acid, and the sample was irradiated up to 20 kGy with or without nitrogen gas-bubbling. The content of chlorophyII b was analyzed by HPLC, and Hunter color value and UV-visible spectra were analyzed during 6 hr of photooxidation. The content of chlorophyll was reduced by irradiation and completely destroyed at 2.517 kGy. The model system with nitrogen gas-bubbling did not develop the lipid oxidation after irradiation or photooxidation at 20 kGy UV-visible spectra showed decreasing values of optical density by increase of irradiation doses, supporting the destruction of chlorophyII b. The results indicate that irradiation technology can be applied to reduce or eliminate the residual chlorophyII and to prolong the shelf-life of oil products.

• Korean Journal of Materials Research
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• v.19 no.10
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• pp.555-561
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• 2009

Expanded graphite (EG) is synthesized by chemical intercalation of natural graphite (NG) and rapid expansion at high temperature, with titanium n-butoxide (TNB) used as titanium source by a sol-gel method to prepare EG-TiO$_2$ composite. The performances of the prepared EG-TiO$_2$ composite are characterized by BET surface area measurement, scanning electron microscopy (SEM), X-ray diffraction patterns (XRD) and energy dispersive X-ray analysis (EDX). To compare the photocatalytic activities of the EG-TiO$_2$ composite, three kinds of dye solutions, methylene blue (MB), methylene orange (MO) and rhodamine B (RhB), and two kinds of light source, UV light and visible light (VL), are used. Comparing the results, it can be clearly seen that the degradation of all of the dye solutions under irradiation by UV light is much better than that under irradiation by visible light, and the decomposition of MB solution was better than that of both of MO and RhB solution.

• Journal of Environmental Science International
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• v.19 no.12
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• pp.1323-1334
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• 2010

The effect of nitric oxide (NO) on antioxidant system and protective mechanism against oxidative stress under UV-B radiation was investigated in leaves of maize (Zea mays L.) seedlings during 3 days growth period. UV-B irradiation caused a decrease of leaf biomass including leaf length, width and weight during growth. Application of NO donor, sodium nitroprusside (SNP), significantly alleviated UV-B stress induced growth suppression. NO donor permitted the survival of more green leaf tissue preventing chlorophyll content reduction and of higher quantum yield for photosystem II than in non-treated controls under UV-B stress, suggesting that NO has protective effect on chloroplast membrane in maize leaves. Flavonoids and anthocyanin, UV-B absorbing compounds, were significantly accumulated in the maize leaves upon UV-B exposure. Moreover, the increase of these compounds was intensified in the NO treated seedlings. UV-B treatment resulted in lipid peroxidation and induced accumulation of hydrogen peroxide ($H_2O_2$) in maize leaves, while NO donor prevented UV-B induced increase in the contents of malondialdehyde (MDA) and $H_2O_2$. These results demonstrate that NO serves as antioxidant agent able to scavenge $H_2O_2$ to protect plant cells from oxidative damage. The activities of two antioxidant enzymes that scavenge reactive oxygen species, catalase (CAT) and ascorbate peroxidase (APX) in maize leaves in the presence of NO donor under UV-B stress were higher than those under UV-B stress alone. Application of 2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3- oxide (PTIO), a specific NO scavenger, to the maize leaves arrested NO donor mediated protective effect on leaf growth, photosynthetic pigment and free radical scavenging activity. However, PTIO had little effect on maize leaves under UV-B stress compared with that of UV-B stress alone. $N^{\omega}$-nitro-L-arginine (LNNA), an inhibitor of nitric oxide synthase (NOS), significantly increased $H_2O_2$ and MDA accumulation and decreased antioxidant enzyme activities in maize leaves under UV-B stress. This demonstrates that NOS inhibitor LNNA has opposite effects on oxidative resistance. From these results it is suggested that NO might act as a signal in activating active oxygen scavenging system that protects plants from oxidative stress induced by UV-B radiation and thus confer UV-B tolerance.

• ALGAE
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• v.29 no.1
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• pp.27-34
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• 2014

Availability of nutrients is known to influence marine primary production; and it is of general interest to see how nutrient limitation mediates phytoplankton responses to solar ultraviolet radiation (UVR, 280-400 nm). The red tide diatom Skeletonema costatum was cultured under nitrate (N)-limited and N-replete conditions and exposed to different solar irradiation treatments with or without UV-A (315-400 nm) and UV-B (280-315 nm) radiation. Its photochemical quantum yield decreased by 13.6% in N-limited cells as compared to that in N-replete ones under photosynthetically active radiation (PAR)-alone treatment, and the presence of UV-A or UV-B decreased the yield further by 2.8 and 3.1%, respectively. The non-photochemical quenching (NPQ), when the cells were exposed to stressful light condition, was higher in N-limited than in N-replete grown cells by 180% under PAR alone, by 204% under PAR + UV-A and by 76% under PAR + UV-A + UV-B treatments. Our results indicate that the N limitation exacerbates the UVR effects on the S. costatum photosynthetic performance and stimulate its NPQ.

• Transactions of Materials Processing
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• v.18 no.4
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• pp.310-316
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• 2009

Micro lens array(MLA) is widely used in information technology(IT) industry fields for various applications such as a projection display, an optical power regulator, a micro mass spectrometer and for medical appliances. Recently, MLA have been fabricated and developed by using a reflow method having the processes of micro etching, electroplating, micro machining and laser local heating. Laser thermal relaxation method is introduced in marking of microdots on the surface of densified glass. In this paper, we have proposed a new direct fabrication process using UV laser local thermal-expansion(UV-LLTE) and investigated the optimal processing conditions of MLA on the surface of negative photo-resist material. We have also studied the 3D shape of the micro lens obtained by UV laser irradiation and the optimal process conditions. And then, we made chrome mold by electroplating. After that, we made MLA using chrome mold by hot embossing processing. Finally, we have measured the opto-physical properties of micro lens and then have also tested the possibility of MLA applications.

• Journal of the Korean Society of Clothing and Textiles
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• v.44 no.6
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• pp.1205-1223
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• 2020

This research investigated the protective effect on hair for 3 commercial hair oil products containing UV filters upon UVA and UVB irradiation. Hair tresses each weighing 2 g were prepared from black virgin hair. Hair tresses treated with 0.5 g of hair oil were irradiated by UVA (365 nm) and UVB (302 nm) lamp for up to 600 hours. Color of hair was measured using a spectrocolorimeter, tensile strength and elongation of hair were measured using a biological tensile tester, surface morphology was examined using a scanning electron microscope. Experimental results were analyzed using SPSS statistical software. Hair color and tensile strength were both affected by UVA and UVB irradiation. Significant differences in the color and tensile strength were observed between untreated hair and hair treated with hair oils. Good UV protective effect observed in Oil 2 and Oil 3 was attributable to the type and the combination of UV filters contained in the products.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.573-574
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• 2008

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1544-1546
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• 2003

In this study, composite materials were put to dry interfacial treatment by use of plasma technology. It has been presented that the optimum parameters for the best wettability of the samples at the time of generation of plasma were oxygen atmosphere, 0.1 torr of system Pressure, 100 W of discharge power, and 3 minutes of discharge time. The decrease in surface potential of charged samples by corona discharge indicates that the amount of accumulated electrical charges reduces and the charges that have been injected lessen rapidly when the duration of UV irradiation increases. The surface resistivity and the tensile strength of plasma treated samples, a longer UV irradiation time resulted in decreased insulation.

• Journal of Animal Reproduction and Biotechnology
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• v.34 no.1
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• pp.20-29
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• 2019

Soy isoflavones have been reported to possess many physiological activities such as antioxidant activity and inhibition of cancer cell proliferation. This study investigated the photoprotective effects of soybean extract in human fibroblast cell line and hairless mice model. Human fibroblast was treated with soybean extract before and after ultraviolet B (UVB; 290-302 nm) irradiation. In the soybean extract treated group, the cells showed better resistance to ultraviolet (UV) than control group. The amount of type I collagen recovered from the soybean treated group was higher than the vehicle group exposed to UV-induced damage. Moreover, increased expression of metalloproteinases-1 as a result of UV irradiation was suppressed by the soybean extract. Female mice were orally administered soybean extract and irradiated with UVB light for 8 weeks. The effects of the soybean extract on the skin appearance, collagen deposition and epidermal thickness in the UV-damaged mouse skin were analyzed using histopathological methods. In soybean extract treated group, the skin had a better morphology than that of the control group. Furthermore, the amount of type I collagen was increased and overexpression of MMP-1 was reduced in the soybean extract group compared to vehicle group. Additionally, up-regulation of pro-inflammatory cytokines induced by UV irradiation was suppressed by dietary soybean extract treatment. It appears that soybean extract had a photoprotective effect, including anti-aging and anti-inflammatory effect, from UV-induced damage in not only human fibroblast, but also hairless mice. We confirmed that these effects were possibly due to promotion of collagen synthesis and inhibition of MMP-1 expression.

• Food Science and Preservation
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• v.21 no.4
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• pp.581-586
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• 2014

With the current consumer trend toward health and wellbeing, the demand for consumption of fresh cut vegetables has been increasing. As a popular vegetable with functional components, sedum (Sedum sarmentosum) is widely used in Korea as a side dish that needs no cooking. In this study, to provide a hurdle technology for postharvest sedum, the effects of combined treatment of 1% acetic acid for washing and $10kJ/m^2$ UV-C irradiation on the microbial growth and quality of sedum were examined. After the treatment, the sedum samples were stored at $10^{\circ}C$ for six days, and the results of their microbial analysis as well as their color, vitamin C content, and antioxidant activity were analyzed. The combined treatment with acetic acid and UV-C irradiation reduced the initial populations of the total aerobic bacteria and the yeast and molds in the sedum by 3.28 and 4.22 log CFU/g, respectively, compared to those in the control. The Hunter L, a, and b values of the sedum did not significantly differ across the treatments. In addition, the vitamin C content and the antioxidant activity decreased significantly during the storage, regardless of the treatment. These results suggest that the combined treatment with 1% acetic acid and $10kJ/m^2$ UV-C irradiation can be useful as a hurdle technology for retaining the microbiological safety and quality of sedum during its storage.