• 한국환경농학회지
• /
• 제39권3호
• /
• pp.273-279
• /
• 2020

BACKGROUND: After transplanting, the recent abnormal low temperature caused physiological disorders of pepper seedlings. This study was conducted to evaluate the effects of UV-A LED, a physical elicitor, on the chilling tolerance of pepper seedlings. METHODS AND RESULTS: Seedlings were continuously irradiated with 370 and 385 nm UV-A LEDs with 30 W·m^-2 for 6 d. After that, seedlings were exposed to 4℃ for 6 h and then recovered under the normal growing condition for 2 d. There were no significant differences in growth characteristics of UV-A treatments compared to the control. Fv/Fm values of two UV-A treatments were below 0.8. Electrolyte leakage in the control was increased by chilling stress, while 385 nm UV-A had the significantly lowest value. Total phenolic content and antioxidant capacity of two UV-A treatments significantly increased due to UV-A radiation. However, total phenolic content and antioxidant capacity of the control increased due to chilling stress and tended to decrease again during the recovery time. CONCLUSION: We confirmed that UV-A light was effective to induce the chilling tolerance of pepper seedling, and the supplemental radiation of 385 nm UV-A LED before transplanting could be used as a cultivation technique to produce high quality pepper seedlings.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
• /
• pp.62-65
• /
• 2001

The effects of accelerated UV radiation on EPDM used for a polymeric insulator were investigated by contact angle, surface voltage decay after corona charging, SEM-EDX, ATR-FTIR and XPS. EPDM occurs as loss of hydrophobicity by UV treatment, which followed by surface cracking and chalking. The surface voltage decay on UV-treated EPDM show that the shorter decay time corresponded to the treated samples with a longer UV exposure time. The surface oxygen and aluminum content were found to increase and carbon decrease, as is observed in EDX analysis. The ATR-FTIR and XPS indicated that C-C and C-H groups decreased and the highly oxidized carbon bonds such as C-O, C=O and O-C=O increase with time. Also, the effects of surface charges on hydrophobicity based on our results is discussed.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
• /
• pp.106-109
• /
• 2001

In this paper, we have investigated the degradation of shed materials of outdoor insulators by UV-radiation by using corona-charging and XPS analysis. The accumulated charges on polymeric surface having intrinsic hydrophobic property have a negative impact on retaining its hydrophobicity. Therefore, shorter decay times of surface charges are preferred. The surface voltage decay on UV-treated silicone rubber and EPDM show a different decay trend with UV treated time. From the XPS analysis, the oxidized groups of silica-like structure in silicone rubber increase with UV treatment time. For EPDM, the oxidized carbon groups of C=O, O=C-O increase as elapse of UV radiation time. These oxidized surface for each material have different electrostatic characteristics, so deposited charges may be expected to have different impacts on their surface hydrophobicity. The degradation mechanism based on our results is discussed.

• 생명과학회지
• /
• 제8권3호
• /
• pp.272-278
• /
• 1998

UV-B 강도 변화가 식물의 생장에 미치는 영향을 조사하기 위하여, 오이를 이용하여 3주간 3단계의 UV-B[일일 평균 UV-$B^{BE}$; 무처리(0.03), 저UV-B(6.40), 고UV-B(11.32) kJ $m^{-2}$]조사 실험을 수행하였다. 3주간의 UV-B 조사에 의해 건물중 및 엽면적은 고UV-B 처리와 저UV-B 처리에서 각각 60%와 40% 정도의 감소를 보였으나, 엽중비는 증가하였다. UV-B에 의해 고UV-B 처리에서 약 45%, 저UV-B 처리에서 약 37%의 광합성속도의 감소를 나타내었으나 증산속도의 변환느 나타나지 않았다. 총 엽록소 함량은 UV-B 강도의 증가에 따라 감소하였으며, UV-흡수물질인 flavonoid의 함량은 고UV-B 처리에서 약 19% 저UV-B처리에서 약 14%의 증가를 보였다. 이상의 결과로 볼 때 UV-B조사는 오이 식물에 극심한 생육 저해를 나타내었으며, 그 피해는 UV-B 강도에 따라 증가하였다. 따라서 현재 지구에 도달하는 태양UV-B에 의해서도 오이식물은 영향을 받고 있는 것으로 사료되며, 장래 예상되는 오존층 감소에 의해서도 생육장해를 나타낼 것으로 사료된다.

• Journal of Electrical Engineering and Technology
• /
• 제6권2호
• /
• pp.275-279
• /
• 2011

Sterilization of Escherichia coli (E. coli) is examined using a unique pulsed ultra-violet (UV) elliptical reactor based on Nd:YAG laser resonator, UV radiation from a pulsed xenon flashlamp. The light from the discharge has a broadband emission spectrum extending from the UV to the infrared region with a rich UV contained. Sterilization method by using the UV light is fast, environment-friendly and it does not cause secondary pollution. A Nd:YAG laser resonator having elliptical shape has advantage of concentrating the radiation of the UV light at two foci as the quart sleeve filled with E. coli. The primary objective of this research is to determine the important parameters such as pulse per second (pps), the applied voltage for sterilizing E. coli by using an UV elliptical reactor. From the experiment result, the sterilization effect of UV elliptical reactor is better than that of UV cylindrical reactor, and it can be 99.9% of sterilization at 800V regardless of the pps within 10 minutes.

• 한국의류학회지
• /
• 제33권5호
• /
• pp.817-826
• /
• 2009

As UV radiation to the earth increased over recent years, many adverse effects of UV radiation have been reported. There are needs to develop UV-protective apparel and accessaries to protect skin from these harmful effects. Cellulose is one of the most frequently worn fiber during summer time. However, celllulose shows very low UV-protective property especially in case of thin and low fabric content. In this study, UV-protective cellulose textiles were developed using chiotsan mordanting and green tea dyeing. The repetition effect of chitosan and green tea treatment were focused. Three different cellulose fibers, cotton, linen, and ramie, were used for this study. All chitosan mordanted and green tea dyed fabrics showed increases in UV-protective property. The color of fabrics tended to darker as the numbers of mordanting process and green tea dyeing increased. UV-protective property did not increase significantly upon the repetition of mordanting and green tea dyeing treatment except ramie fabric. UV protective property was persisted upon washfastness test in all three cellulose fiber types.

• 미생물학회지
• /
• 제52권1호
• /
• pp.65-73
• /
• 2016

이 논문은 서울 한강물에서 분리한 방사선 내성 세균군집과 분리된 신종 세균의 UV 내성 특성에 관한 내용이다. 세균은 R2A agar와 1/10 R2A agar를 사용하여 3 kGy가 조사된 한강물에서 분리되었다. 그 결과 방사선에 내성을 가지는 것으로 추측되는 균주를 60주 분리하였고, 본 연구 분석 자료로 사용하였다. 16S rRNA 유전자 염기서열 분석을 통해 분리균주 60개의 계통수를 파악한 결과, 3개의 문(4개의 속)이 확인되었고, Deinococcus-Thermus (Deinococcus)가 61.7%, Firmicutes(Exiguobacterium)는 15%, Bacteroidetes (Hymenobacter, Spirosoma)는 23.4%의 비중을 나타냈다. 분리균주 중 29개 균주가 Deinococcus, Hymenobacter, Spirosoma에 속하는 신종 또는 다른 신속으로 분류될 가능성을 보였으며, 앞으로 추가적인 신종 실험이 진행될 예정이다. 그리고 신종 예상균주를 9개 선정하여 UV 내성 실험을 진행한 결과, 9개 균주 모두 D. radiodurans $R1^T$ 균주 만큼 높은 UV 내성을 가지는 것으로 나타났다. 또한 분리된 Firmicutes (Exiguobacterium) 균주는 아직까지 방사선 내성 연구 보고가 되어 있지 않아서 추가적인 방사선 내성 연구가 필요하다.

• Journal of Photoscience
• /
• 제8권1호
• /
• pp.1-7
• /
• 2001

The deteriorative effect of ultraviolet-B(UV-B) radiation on photosynthesis was assessed by the simultaneous measurement of O$_2$ evolution and chlorophyll(Chl) fluorescence in green pepper. UV-B was given at the intensity of 1 W$.$m$\^$-2/, a dosage often encountered in urban area of Seoul in Korea, to detached leaves. Both Pmax and quantum yield of O$_2$ evolution was rapidly decreased, in a parallel phase, with increasing time of UV-B treatment. Chl fluorescence parameters were also significantly affected. Fo was increased while both Fm and Fv were decreased. Photochemical efficiency of PSII(Fv/Fm) was also declined, although to a lesser extent than Pmax. Both qP and NPQ were decreased similarly with increasing time of UV-B treatment. However, PS I remained stable. The addition of lincomycin prior to UV-B treatment accelerated the decline in Fv/Fm to some extent, suggesting that D1 protein turnover may play a role in overcoming the harmful effect of UV-B. The amount of photosynthetic pigments was less affected than photosynthetic response in showing decline in Chl a and carotenoids after 24 h-treatment. Presumptive flavonoid contents, measured by changes in absorbance at 270 nm , 300 nm and 330nm, were all increased by roughly 50% after 8 h-treatment. Among antioxidant enzymes, activities of catalase and peroxidase were steadily increased until 12h of UV-B treatment whereas ascorbate perxidase, dehydroascorvate reductase and glutathione reductase did not show any significant change. The results indicate that deteriorative effect of UV-B on photosynthesis precedes the protection exerted by pigment synthesis and antioxidant enzymes.

• Macromolecular Research
• /
• 제11권3호
• /
• pp.146-151
• /
• 2003

The dependence of electrical conductivity on concentrations of diallyldimethylammonium chloride (DADMAC) monomer, linear poly(DADMAC) and their mixture monomer/poly(DADMAC) in dilute aqueous solution exhibits a linear relationship. It was possible to calculate conversion of DADMAC polymerization by measuring its electric conductivity. Although the electrical conductivity of the poly(DADMAC) solution decreased with increasing its molecular weight, in the process of UV or ionizing radiation polymerization the molecular weight of the polymers could be kept constant in the case of fixed temperature, UV-luminous intensity or dose rate. Based on the method mentioned above, the kinetics of UV induced polymerization of DADMAC in aqueous solution was studied; the overall activation energy of polymerization of DADMAC in the water phase was calculated to be 18.8 kJ mol$^{-1}$ . ${\gamma}$-Radiation-induced polymerization of DADMAC in aqueous solution as a function of absorbed dose was studied as well. The conversion of DADMAC increased quickly with dose before 30 kGy and then increased slowly. The experimental data of both UV- and ${\gamma}$-induced polymerization were verified to be reliable by inverted ultracentrifugation method.

• 한국환경과학회지
• /
• 제16권12호
• /
• pp.1345-1353
• /
• 2007

The effect of salicylic acid(SA) on antioxidant system and protective mechanisms against UV-B induced oxidative stress was investigated in cucumber(Cucumis sativus L.) leaves. UV-B radiation and SA were applied separately or in combination to first leaves of cucumber seedlings, and dry matter accumulation, lipid peroxidation and activities of antioxidant enzymes were measured in both dose and time-dependant manner. UV-B exposure showed reduced levels of fresh weight and dry matter production, whereas SA treatment significantly increased them. SA noticeably recovered the UV-B induced inhibition of biomass production. UV-B stress also affected lipid peroxidation and antioxidant enzyme defense system. Malondialdehyde(MDA), a product of lipid peroxidation, was greatly increased under UV-B stress, showing a significant enhancement of a secondary metabolites, which may have antioxidative properties in cucumber leaves exposed to UV-B radiation. Combined application of UV-B and SA caused a moderate increase in lipid peroxidation. These results suggest that SA may mediate protection against oxidative stress. UV-B exposure significantly increased SOD, APX, and GR activity compared with untreated control plants. Those plants treated with 1.0 mM SA showed a similar pattern of changes in activities of antioxidant enzymes. SA-mediated induction of antioxidant enzyme activity may involve a protective accumulation of $H_2O_2$ against UV-B stress. Moreover, their activities were stimulated with a greater increase by UV-B+SA treatment. The UV-B+SA plants always presented higher values than UV-B and SA plants, considering the adverse effects of UV-B on the antioxidant cell system. ABA and JA, second messengers in signaling in response to stresses, showed similar mode of action in UV-B stress, supporting that they may be important in acquired stress tolerance. Based on these results, it can be suggested that SA may participates in the induction of protective mechanisms involved in tolerance to UV-B induced oxidative stress.