• Microbiology and Biotechnology Letters
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• v.11 no.3
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• pp.155-161
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• 1983

The effects of ultraviolet light on bacteriophage f2 were investigated to determine the inactivation kinetics and its mechanism. The 260nm light showed a little higher inactivation rate than the one of 300 nm. In this work, our main concern was whether structural and/or conformational changes in the protein capsid could occur by UV irradiation. The inactivation for the first 20 minutes irradiation was rapid with a loss of about 4 logs and followed by a slower rate during the next 40 minutes with no survival noted in the samples irradiated for 90 minutes or longer. The structural change of the protein capsid was examined by optical spectroscopic techniques and electron microscopy. The absorption spectra of the UV irradiated phages showed no detectable differences in terms of the spectral shape and intensity from the control phage. However, the fluorescence emission spectroscopic data, i.e. 1) fluorescence quenching of tryptophan residues upon irradiation of 300 nm light, 2) enhancement of fluorescence emission of ANS (8-aniline-1-naphthalene sulfonate) bound to the intact phages compared to the one in the UV-treated phages, and 3) decrease of energy transfer efficiency from tryptophan to ANS in the UV-treated samples, presented remarkable differences between the intact and UV-treated phages. Such a structural alteration was also observed by electron microscopy The UV-treated phages appeared to be broken and empty capsids. Therefore, the inactivation of the bacteriophage f2 by UV irradiation is thought to be attributed to the structural change in the protein capsid as well as damage in the viral RNA by UV irradiation.

• Journal of Powder Materials
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• v.29 no.5
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• pp.418-423
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• 2022

Carbon fibers (CFs) are considered promising composite materials for various applications. However, the high cost of CFs (as much as $26 per kg) limits their practical use in the automobile and energy industries. In this study, we developed a continuous stabilization process for manufacturing low-cost CFs. We employed a textile-grade polyacrylonitrile (PAN) fiber as a low-cost precursor and UV irradiation technique to shorten the thermal stabilization time. We confirmed that UV irradiation on the textile-grade PAN fibers could lower the initial thermal stabilization temperature and also lead to a higher reaction. These resulted in a shorter overall stabilization time and enhancement of the tensile properties of textile-grade PAN-based CFs. Our study found that only 70 min of stabilization time with UV irradiation was required to prepare textile-grade PAN-based low-cost CFs with a tensile strength of 2.37 ± 0.22 GPa and tensile modulus of 249 ± 5 GPa.

• Journal of Life Science
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• v.12 no.3
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• pp.274-280
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• 2002

The metabolites related to phenylpropanoid pathway play an important role in the self-defense of plants and induced by environmental stress like wounding, pathogen attack, UV-irradiation and so on. The mRNA level of rite phenylalanine ammonia lyase (PAL) was increased at 12 h to 48 h, however it was gradually decreased 48 h to 60 h after UV irradiation. The PAL enzyme activities in rice were peaked at the time of 24 h after UV irradiation, on the other hand, it was not affected by wounding. The PAL enzyme activities in pepper were raised high at 24 h and 10 h by UV irradiation and wounding respectively. The cinnamic acid 4-hydroxylase (C4H) activities were increased by wounding treatment and were detected from 12 h to end time point of experiment, while UV-irradiation didn't affect the C4H activity in rice and pepper. These results were assumed that the action of isoflavonid has an alternative effect on the defenses which include wounding and UV irradiation and on the diverse roles in rice and hot pepper.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.173-176
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• 2000

In this paper, we investigated the surface degradation of HTV silicone rubber used for a polymeric insulator by UV irradiation. To study the surface ageing properties by W irradiation, we used the corona discharge charging and contact angle. Therefore, we observed the change of surface charge retention and decrease of surface hydrophobicity. Also, we discussed the chemical change in the surface range using the analytic equipment such as SEM, ATR-FTIR, ESCA. Therefore, it is found that the scissor of characteristic bonding and the reattachment of oxidant bonding was developed by UV rays radiation. As discussing the corona ischarge charging and the change of contact angle, it is found the effect of UV irradiation and the mechanism of chemical reaction

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.3
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• pp.253-260
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• 2013

Purpose: To investigate the UV-B blocking rate of eyeglasses lens which can prevent enzymes denaturation in cornea. Methods: The denaturation degree of RNase A and catalase, superoxide dismutase (SOD) was determined by using Acrylamide gel electrophoresis after UV-B irradiation of 312 nm for 1, 3, 6, 24 and 96 hours. Also, the inhibitory effect of eyeglasses lens having UV-B blocking rate of 50%, 80%, 95% and 99% on the enzymes denatration was measured. Results: The denaturation of RNase A was induced by 1 hour-irradiation of UV-B. To inhibit RNase A denaturation after UV-B irradiation between 1 hour and 6 hours, UV-B blocking lens of 95% were effective. UV-B blocking lens of 99% suppressed the inhibition of RNase A denaturation after the UV-B exposure between 24 hours and 96 hours. The denaturation of catalase was not induced by 1 hourirradiation of UV-B. To inhibit enzyme denaturation after UV-B irradiation between 1 hour and 6 hours, UV-B blocking lens of 50% were effective. UV-B blocking lens of 95% suppressed the inhibition of enzyme denaturation induced by UV-B irradiation between 24 hours and 96 hours. The SOD denaturation was not induced by UV-B irradiation shorter than 6 hours exposure. The UV-B blocking lens of 50% could inhibit SOD denaturation after the UV-B irradiation for 24 hours. When SOD was exposed to UV-B for 96 hrs, SOD denaturation was inhibited by eyeglasses lens with UV blocking rate higher than 95%. Conclusions: The results demonstrated that the proper UV-B blocking rates of eyeglasses lens to inhibit the enzymes denaturatioin was different according to the types of enzymes and its inhibitory effect was effective only when eyeglasses lens had higher than certain UV-B blocking rate.

• Korean Journal of Food Science and Technology
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• v.44 no.5
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• pp.634-637
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• 2012

In strawberry production, among others, the high incidence of diseases by pathogenic fungi resulting in the reduction of fruit yield and quality requires the development of eco-friendly management systems rather than chemical sprays to control them. The diameter of colonies grown in media at $25^{\circ}C$ for 5 days was measured to evaluate the in vitro inhibition of mycelial growth of 5 pathogenic fungi by irradiation with ultraviolet (UV-C, 264 nm). The mycelial growth of 5 pathogenic fungi was inhibited in potato dextrose agar (PDA) by the irradiation of UV-C for 1 hour a day, and was dramatically inhibited by the irradiation of UV-C for 9-12 h a day. The irradiation of UV-C for 9-12 h a day inhibited completely the growth of the late blight pathogen, Phytophthora cactorum. The irradiation distance of 40 to 50 cm was effective for the inhibition of mycelial growth of fungi. The mycelial growth of fungi without pre-incubation was inhibited strongly by UV-C irradiation compared to fungi pre-incubated for 2 days without light. The mycelia growth of Colletotrichum gloeosprioides and Fusarium oxysporum was inhibited strongly by UV-C irradiation in vegetable 8 juice agar compared to PDA.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.11
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• pp.1632-1638
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• 2012

The effects of combined treatment of aqueous $ClO_2$ and UV-C or electron beam irradiation on microbial growth and quality in chicon during storage at $4^{\circ}C$ were investigated. Samples were treated separately with 50 ppm of $ClO_2$, 5 kJ/$m^2$ of UV-C, 2, 5, 7, and 10 kGy of electron beam irradiation, as well as a combination of $ClO_2$ and UV-C or 2 kGy of electron beam irradiation. The populations of total aerobic bacteria as well as yeast and molds in the chicon samples were determined following each treatment. The populations of total aerobic bacteria in the chicon samples decreased by 1.49~2.92 log CFU/g following combined treatment of $ClO_2$ and UV-C irradiation compared to the control, whereas the populations of yeast and molds decreased by 1.63~1.78 log CFU/g. On the contrary, following combined treatment of $ClO_2$ and electron beam irradiation, the populations of total aerobic bacteria as well as yeast and molds in the chicon samples were undetectable during storage. Color measurements indicated that Hunter $L^*$, $a^*$, and $b^*$ values were not significantly different among the treatments during storage. These results suggest that combined treatment of $ClO_2$ and electron beam irradiation can be useful for improving microbiological safety in chicon during storage.

• Journal of Sensor Science and Technology
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• v.18 no.1
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• pp.48-53
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• 2009

$Eu^{2+}$-doped ${SrAl_2}{O_4}$ and $Eu^{2+}$, $Dy^{3+}$ co-doped ${SrAl_2}{O_4}$ phosphors have been synthesized by conventional solid state method. Photocurrent properties of $Eu^{2+}$ doped ${SrAl_2}{O_4}$ and $Eu^{2+}$, $Dy^{3+}$ co-doped ${SrAl_2}{O_4}$ phosphors, in order to elucidate $Dy^{3+}$ co-doping effect, during and after ceasing ultraviolet-ray (UV) irradiation have been investigated. The photocurrent of $Eu^{2+}$, $Dy^{3+}$ co-doped ${SrAl_2}{O_4}$ phosphors during UV irradiation was 4-times lower than that of $Eu^{2+}$-doped ${SrAl_2}{O_4}$ during UV irradiation, and 7-times higher than that of $Eu^{2+}$-doped ${SrAl_2}{O_4}$ after ceasing UV irradiation. The photocurrent results indicated that holes of charge carriers captured in hole trapping center during the UV irradiation and liberated after-glow process, and made clear that $Dy^{3+}$ of co-dopant acted as a hole trap. The photocurrent of ${SrAl_2}{O_4}$ showed a good proportional relationship to UV intensity in the range of $1{\sim}5mW/cm^2$, and $Eu^{2+}$-doped ${SrAl_2}{O_4}$ was confirmed to be a possible UV sensor.

• Preventive Nutrition and Food Science
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• v.14 no.3
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• pp.226-232
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• 2009

The effects of UV-C irradiation on the quality characteristics of powdered foods, sunsik and misutkaru, were examined during storage, where samples were irradiated at doses of 27, 54, and 108 kJ/$m^2$, respectively. In addition, sunsik and misutkaru samples were inoculated with Enterobacter sakazakii as a pathogen and then irradiated at doses of 0.5, 1, and 5 kJ/$m^2$, respectively. After treatment, the sunsik and misutkaru samples were stored at $20^{\circ}C$. The microbiological data represented that populations of total aerobic bacteria, Bacillus cereus, and E. sakazakii were significantly (p<0.05) reduced with increasing UV-C doses. In addition, UV-C irradiation did not cause inferiority in the color quality of the samples during storage. Sensory evaluation results also indicated that there were no significant differences (p<0.05) among the irradiated samples. These results suggest that UV-C irradiation may be useful in maintaining the quality of sunsik and misutkaru during storage.

• Food Science and Preservation
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• v.16 no.5
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• pp.636-643
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• 2009

Inactivation by UV-C irradiation of Escherichia coli O157:H7 and Listeria monocytogenes inoculated onto washed carrots was examined. Carrot samples were inoculated with 6-7 log CFU/mL of E. coli O157:H7 or L. monocytogenes, treated with doses of 0, 1, 3, 5, or $10\;kJ/m^2$ UV-C, and stored at $4{\pm}1^{\circ}C$ for 8 d. The populations of E. coli O157:H7 and L. monocytogenes significantly decreased with increasing irradiation dose (p<0.05). In particular, E. coli O157:H7 and L. monocytogenes populations fell significantly by 2.35 and 2.38 log CFU/g at $10\;kJ/m^2$, respectively, compared to control values. UV-C irradiation inhibited color changes and decreased the whiteness index in carrot during storage, compared to controls. Sensory evaluation results showed that UV-C-treated carrots had better sensory characteristics than did the control. Therefore, the results suggest that UV-C irradiation could be useful to improve the microbial safety and sensory qualities of fresh-cut carrots during storage.