• Journal of Korean Society of Water and Wastewater
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• v.20 no.5
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• pp.755-761
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• 2006

Recently, there is growing interest in ultraviolet (UV) irradiation as a disinfection technic in drinking water production due to its effectiveness to inactivate microorganisms such as Crytosporidium parvum without forming disinfection byproducts. However, UV disinfection is known for its drawback such as photoreactivation. Despite many works concerning the photoreactivation, most of works were focused on indicator or non pathogenic microorganisms. The objective of this study is to examine the photoreactivation of Pseudomonas aeruginosa which is an opportunistic pathogen as UV radiation by LP and MP UV lamp was applied. The result showed that P. aeruginosa had high photo repair efficiency regardless of the type of UV irradiation. Both of the effective log repair values of LP and MP UV irradiation were found approximately 2.6 log. In addition, photo repaired P. aeruginosa was not significantly different in forming biofilm in comparison with non treated P. aeruginosa.

• Food Science of Animal Resources
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• v.34 no.6
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• pp.815-821
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• 2014

The effects of ultraviolet (UV) radiation were investigated with regards to the microbial growth inhibitory effect on the shelf life of Korean native cattle (Hanwoo) beef prior to refrigerated storage. The Hanwoo samples were exposed to UV radiation ($4.5mW/cm^2$) for 0, 5, 10, 15, and 20 min. The UV-irradiated beef that was exposed for 20 min showed significantly reduced mesophilic and psychrotrophic bacterial populations to the extent of approximately 3 log cycles, as compared to that of non-irradiated beef. About 2.5 Log CFU/g of mesophilic bacteria were different compared with UV-irradiated and non-irradiated meat. UV irradiation showed the most significant growth inhibition effects on mesophilic and psychrotrophic bacteria. Coliform and Gram-negative bacteria were also reduced by 1 log cycle. The population of L. monocytogenes, S. Typhimurium, and E. coli O157:H7 decreased significantly to 53.33, 39.68, and 45.76% after 10 min of UV irradiation. They decreased significantly to 84.64, 80.76, and 84.12%, respectively, after 20 min of UV irradiation. The results show that UV irradiation time and the inhibitory effect were proportional. These results verified that UV radiation prior to refrigeration can effectively reduce the number of pathogenic bacteria on the surface of meat and improve the meat's microbial safety.

• Journal of Ginseng Research
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• v.30 no.4
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• pp.188-193
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• 2006

We induced the activation of melanocytes in the epidermis of C57BL/6 mice by ultraviolet B (UVB) irradiation and observed the effect of red ginseng (RG) on the formation, and decrease of UVB-induced epidermal mel-anocytes. C57BL/6 mice were irradiated by UVB $80mJ/cm^2$ (0.5 mW/sec) daily for 7 days, and RG was intraperitoneally or topically applied pre- or post-irradiation. For the estimation of change of epidermal melanocytes, light microscopic observation with dihydroxyphenylalanine (DOPA) stain was performed. Split epidermal sheets prepared from the ear of untreated mice exhibited 11-16 $melanocytes/mm^2$, and one week after UV irradiation, the applied areas show an increased number of strongly DOPA-positive melanocytes with stout dendrites. But intraperitoneal or topical treatment with RG before each irradiation interrupted UVB-induced pigmentation and resulted in a marked reduction in the number of epidermal melanocytes as compared to radiation control skin. The number and size of DOPA-positive epidermal mel-anocytes were also significantly decreased in intraperitoneally injected or topically applicated group after irradiation with RG at 3rd and 6th weeks after irradiation. The present study suggests the RG as inhibitor of UVB-induced pigmentation and depigmenting agent.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.6
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• pp.469-480
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• 2019

This study was conducted to evaluate the degradation and mineralization of PPCPs (Pharmaceuticals and Personal Care Products) using a CBD(Collimated Beam Device) of UV/H₂O₂ advanced oxidation process. The decomposition rate of each substance was regarded as the first reaction rate to the ultraviolet irradiation dose. The decomposition rate constants for PPCPs were determined by the concentration of hydrogen peroxide and ultraviolet irradiation intensity. If the decomposition rate constant is large, the PPCPs concentration decreases rapidly. According to the decomposition rate constant, chlortetracycline and sulfamethoxazole are expected to be sufficiently removed by UV irradiation only without the addition of hydrogen peroxide. In the case of carbamazepine, however, very high UV dose was required in the absence of hydrogen peroxide. Other PPCPs required an appropriate concentration of hydrogen peroxide and ultraviolet irradiation intensity. The UV dose required to remove 90% of each PPCPs using the degradation rate constant can be calculated according to the concentration of hydrogen peroxide in each sample. Using this reaction rate, the optimum UV dose and hydrogen peroxide concentration for achieving the target removal rate can be obtained by the target PPCPs and water properties. It can be a necessary data to establish design and operating conditions such as UV lamp type, quantity and hydrogen peroxide concentration depending on the residence time for the most economical operation.

• Applied Microscopy
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• v.28 no.2
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• pp.127-137
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• 1998

This study was observed of the skin that changed after irradiation of the ultraviolet A. All the mouse were hairless which the weight are about 25g and the ages $6\sim8$ weeks old. The mouse were divided into six groups; control, irradiated for 6 hours, 3 days, 7 days, 14 days, 21 days and 28 days. Each group was irradiated with ultraviolet that is $320nm\sim366nm$ of wavelengths. After irradiated, the skin was observed with the electron microscope and the light microscope. The results are as follow: 1) Light microscopy With following irradiation, the epidermis was not changed to most groups but at the 28 days group was thickened and deposit the melanocyte. The elastic fibers within the epidermis were thickened and twisted with following irradiation. 2) Eelectron microscopy The elastic fibers were slightly clumped at 6 hours group, mildly increased and partly aggregated in the 3 days group, branched and tangled at 7 days group, irregulated and electron density at 14 days group, sightly thickened and twisted at 21 days group, and randomly arranged, shortened, twisted, and electron density at 28 days group.

• Electrical & Electronic Materials
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• v.7 no.2
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• pp.94-99
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• 1994

The purpose of this work is to investigate the interface characteristics of hydrogenated amorphous silicon thin films prepared by PECVD and photo-induced CVD and to examine the annealing effects of ultraviolet irradiation on hydrogenated amorphous silicon thin films which were degraded by visible light illumination. The interface layer thickness of films deposited by photo-induced CVD was about 600-900.angs. while that by PECVD was about 1000-1300.angs.. These results can show that the quality of interface layer in photo induced CVD film is better than that in PECVD sample. The electrical properties are improved by ultraviolet irradiation on visible light soaked a-Si:H films using photo-CVD light sources, probably due to the fact that UV generates phonons in a-Si:H films and anneal the meta stable defects.

• Journal of the Korean Chemical Society
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• v.6 no.1
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• pp.64-68
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• 1962

The graft polymerization of styrene to polyvinyl alcohol using a photosensitizer(benzophenone) and ultraviolet light was studied. Styrene was grafted onto polyvinyl alcohol up to when polyvinyl alcohol was pre-immersed in water and irradiated by ultraviolet light for 24 hours styrene solution of benzophenone(0.01 molarity). The highest percentage of graft obtained in the grafting which was proceeded in the presence of water added immediately before irradiation was 29%. The grafting was proportional to irradiation time within a certain limit of time, i.e., 24 hours, and presumably was initiated at the surface. After a certain degree of grafting a definite maximum was reached. Graft polymer prepared in this experiment showed high resistance to various solvents.

• Elastomers and Composites
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• v.33 no.5
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• pp.363-369
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• 1998

Photografting reaction onto styrene-butadiene rubber (SBR) as a function of monomer concentration, irradiation time and carbon black content has been studied using ultraviolet (UV). Acrylamide and benzophenone are used as monomer and photoinitiator, respectively. FT-IR ATR and static contact angle analysis using distilled water are used to measure the graft ratio of acrylamide onto SBR surface. Graft ratio of acrylamide increases with acrylamide concentration and irradiation time and contact angle tends to decrease with increasing graft ratio. It is observed that graft ratio increases with carbon black content.

• Nutrition Research and Practice
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• v.1 no.4
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• pp.279-284
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• 2007

Solar ultraviolet (UV) irradiation leads to distinct changes in the skin connective tissues by degradation of collagen, which is a major structural component in the extracellular matrix. UV irradiation induces the production of matrix metalloproteinases (MMP) capable of attacking native fibrillar collagen and responsible for inhibiting the construction of collagenous extracellular matrix. In this study, we attempted to investigate the protective actions of Rubus coreanus ethanol extract (RCE) on the MMP production and the consequent procollagen/collagen degradation in UV-B-irradiated human dermal fibroblasts. The analytical data showed that Rubus coreanus ethanol extract was mostly comprised of cyanidin 3-rutinoside. Pre-treatment of fibroblasts with this extract inhibited UV-B-induced production of MMP-1, MMP-8 and MMP-13 in dose-dependent manners. In addition, Western blot analysis and immunocytochemical staining assay revealed that RCE markedly augmented the cellular levels of procollagen/collagen declined in UV-B-exposed dermal fibroblasts. These results demonstrate that RCE blocks UV-B-induced increase of the collagen degradation by inhibiting MMP production. Thus, RCE may act as an agent inhibiting excessive dermal collagen degradation leading to the skin photoaging.

• Preventive Nutrition and Food Science
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• v.7 no.3
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• pp.238-244
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• 2002

Protective effect of skin by antioxidative dietary buchu (Chinese chives, Allium tuberosum Router), was evaluated in ICR mice fed diets containing 2% or 5% buchu for 12 months. Lipid peroxidation and protein oxidation in skin, with or without ultraviolet B (UVB) irradiation, activities of antioxidative enzymes, total glutathione concentrations, and non-soluble collagen contents were measured. Dietary buchu decreased significantly in TBARS and protein carbonyl levels in skin compared to the control group, and were lower in those fed 5% than 2% buchu diet group. ICR mice exhibited an age-dependent decrease in antioxidative enzyme activities and total glutathione concentrations on the control diet, but in the groups fed buchu diet the enzyme activities and glu-tathione concentrations remained at youthful levels for most of the study. SOD, glutathione peroxidase, and catalase activities as well as total glutathione concentrations increased with time in the skins of the mice fed buchu diets. Lipid peroxidation and protein oxidation provoked by UVB irradiation on ICR mice skin homogenates were also significantly inhibited by dietary buchu. The buchu diets also decreased the formation of non-soluble collagen in mice skin, compared to the control group. These results suggest that antioxidative components and sulfur-compounds in buchu may confer protective effect against oxidative stress resulting from aging and exposure to ultraviolet irradiation.