• 한국식품영양학회지
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• 제20권2호
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• pp.120-124
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• 2007

천연 항산화제로 사용되는 토코페롤은 가열 온도가 높을수록, 가열 시간이 길수록 토코페롤의 분해율이 증가하였으며, 무산소 가열의 경우, 토코페롤은 산소가 있을 때 보다 덜 분해되었다. 알파-, 감마-. 델타- 토코페롤의 무산소 가열 조건을 만들기 위하여 $100{\sim}250^{\circ}C$에서 5${\sim}$60분 가열하는 동안 회화로 속으로 질소를 계속 흘려보내는 실험 방법을 사용하였다. 헥산으로 추출한 토코페롤은 두 종류의 용출 용매와 역상 ${\mu}$-Bondapak C$_{18}$-컬럼을 사용한 HPLC로 분리하였고 토코페롤의 분해 패턴과 잔존량을 조사하였다. 토코페롤의 열분해 키네틱스는 온도와 시간의 함수로 분석되었고 열분해 패턴은 1차 반응으로 나타났다. 무산소 가열시 알파-, 감마-, 델타-토코페롤의 열분해 활성화 에너지는 각각 3.47, 5.85 그리고 6.76 kcal/mole 이었다.

• 전기학회논문지
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• 제58권7호
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• pp.1450-1455
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• 2009

Assumed that an IPTV camera system is to be used as an ad-hoc sensor for the surveillance and diagnostics of safety-critical equipments installed in the in-containment building of the nuclear power plant, an major problem is the presence of high dose-rate gamma irradiation fields inside the one. In order to uses an IPTV camera in such intense gamma radiation environment of the in-containment building, the radiation-weakened devices including a CCD imaging sensor, FPGA, ASIC and microprocessors are to be properly shielded from high dose-rate gamma radiation using the high-density material, lead or tungsten. But the passive elements such as mirror, lens and window, which are placed in the optical path of the CCD imaging sensor, are exposed to a high dose-rate gamma ray source directly. So, the gamma-ray irradiation characteristics of the passive elements, is needed to test. A CCD camera lens, made of glass material, have been gamma irradiated at the dose rate of 4.2 kGy/h during an hour up to a total dose of 4 kGy. The radiation induced color-center in the glass lens is observed. The degradation performance of the gamma irradiated lens is explained using an color component analysis.

• Journal of Radiation Protection and Research
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• 제34권1호
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• pp.9-14
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• 2009

High density polyethylene (HDPE) is degraded due to a radiation-induced oxidation when it is used as a neutron moderator in a neutron counter for a nuclear material accounting of spent fuels. The HDPE exposed to the gamma-ray emitted from the fission products in a spent nuclear fuel results in a radiation-induced degradation which changes its original molecular structure to others. So a neutron moderating power variation of HDPE, irradiated by a gamma radiation, was investigated in this work. Five HDPE moderator structures were exposed to the gamma radiation emitted from a $^{60}Co$ source to a level of $10^5-10^9$ rad to compare their post-irradiation properties. As a result of the neutron measurement test with 5 irradiated HDPE structures and a neutron measuring system, it was confirmed that the neutron moderating power for the $10^5$ rad irradiated HDPE moderator revealed the largest decrease when the un-irradiated pure one was used as a reference. It implies that a neutron moderating power variation of HDPE is not directly proportional to the integrated gamma dose rate. To clarify the cause of these changes, some techniques such as a FTIR, an element analysis and a densitometry were employed. As a result of these analyses, it was confirmed that the molecular structure of the gamma irradiated HDPEs had partially changed to others, and the contents of hydrogen and oxygen had varied during the process of a radiation-induced degradation. The mechanism of these changes cannot be explained in detail at present, and thus need further study.

• 제어로봇시스템학회논문지
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• 제17권12호
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• pp.1203-1209
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• 2011

In this paper, the degradation evaluation method of VLC (Visible Light Communication) wireless module after high dose rate gamma-ray irradiation using the thermal infrared camera is proposed. First, the heating characteristics of the active devices embedded in the VLC wireless module during the condition of normal operation is monitored by thermal infrared camera. By the image processing technique, the trends of the intensity of the heat emitted by the active devices are calculated and stored. The feature of the blob area including the area of the active devices in the thermal infrared image is extracted and stored. The feature used in this paper is the mean value of the gray levels in the blob area. The same VLC module has been gamma irradiated at the dose rate of about 4.0 kGy/h during 72 hours up to a total dose of 288 kGy. And then, the heating characteristics of the active devices embedded in the VLC wireless module after high dose gamma ray irradiation is observed by thermal infrared camera. The high dose gamma-ray induced degradation of the active devices embedded in the VLC module was evaluated by comparing the mean value of the blob area to the one of the same blob area of the VLC module before the gamma ray irradiation.

• 환경생물
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• 제23권4호
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• pp.405-408
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• 2005

To induce the enhanced mutants of dinitroaniline herbicide pendimethalin degrading bacterium, Bacillus sp. MS202 was irradiated with gamma radiation at the dose of $LD_{99}$ (3.35 kGy). Three enhanced mutants (MS202m7, MS202m14, MS202m18) were isolated from the candidates by the generation - isolation method. Clear zone formation and the GC analysis confirmed that the degrading activity of each enhanced mutant (MS202m7, MS202m14, MS202m18), the formation of pendimethalin metabolite, increased by $11\%,\;45\%,\;and\;32\%$ than a wild type, respectively. It suggested that these mutants induced by gamma radiation could be useful for the application of pesticide degradation.

• Journal of Microbiology and Biotechnology
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• 제28권2호
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• pp.314-322
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• 2018

Bacillus subtilis 8 is highly efficient at degrading feather keratin. We observed integrated feather degradation over the course of 48 h in basic culture medium while studying the entire process with scanning electron microscopy. Large amounts of ammonia, sulfite, and $\text\tiny{L}$-cysteic acid were detected in the fermented liquid. In addition, four enzymes (gamma-glutamyltranspeptidase, peptidase T, serine protease, and cystathionine gamma-synthase) were identified that play an important role in this degradation pathway, all of which were verified with molecular cloning and prokaryotic expression. To the best of our knowledge, this report is the first to demonstrate that cystathionine gamma-synthase secreted by B. subtilis 8 is involved in the decomposition of feather keratin. This study provides new data characterizing the molecular mechanism of feather degradation by bacteria, as well as potential guidance for future industrial utilization of waste keratin.

• 방사선산업학회지
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• 제4권4호
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• pp.385-389
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• 2010

In this study, the effect of the concentration of carboxymethylcellulose (CMC) solution on the degradation by irradiation was investigated. The CMC solutions with different concentrations of 3%, 4%, 5%, 6% and 7% were irradiated at the doses of 5, 10, 15, 20, 25 and 30 kGy with gamma ray or electron beam, and the viscosity of CMC solution was measured. The viscosity of the CMC solutions was decreased with an increase in the irradiation dose, but the extent of the degradation by an irradiation was found to be decreased with an increase of the CMC concentration in the solution. The dependency of the irradiation sources showed that an electron beam radiation had degraded the CMC less severely than gamma ray.

• Preventive Nutrition and Food Science
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• 제12권3호
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• pp.131-134
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• 2007

The kinetic analyses for thermal products of alpha-, gamma- and delta-tocopherols during heating as functions of temperature and time were studied. Alpha-, gamma- and delta-tocopherols dissolved in glycerol were heated at $100{\sim}200^{\circ}C$ for $5{\sim}60$ min. The thermal products were separated by hexane extraction and analyzed by HPLC using a reversed phase ${\mu}-Bondapak$ $C_{18}-column$ with two kinds of elution solvents in a gradient mode. The formation kinetics of thermal products of tocopherols followed a first-order kinetic model. The formation rate of thermal products of tocopherols was dependent on heating temperatures and heating times. The activation energy and enthalpy for the thermal products of ${\gamma}-and$ ${\delta}-tocopherols$ were higher than those for ${\alpha}-tocopherol$ as in the case of the oxidative degradation kinetics of tocopherol. The magnitude order of the activation energy was ${\gamma}->{\delta}->{\alpha}-tocopherol$.

• Nuclear Engineering and Technology
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• 제56권5호
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• pp.1777-1780
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• 2024

Chemical and thermal characteristics of cation exchange resins were examined after irradiation of gamma rays. The degradation of cation exchange resins was mainly observed at doses of up to 500 kGy, whereas the balance between degradation and cross-linking reactions was sustained at 700 kGy. While the carbon content decreased significantly up to a maximum dose of 500 kGy, it showed an increase at higher doses. Conversely, the oxygen content exhibited a decrease in contrast to the carbon content. The continuous reduction in sulfur content was attributed to the decomposition of sulfonic groups. Gamma-ray irradiation caused a decrease in the initiation temperature of sulfonic groups and PS-DVB, but unlike the chemical properties of cation exchange resins due to gamma-ray irradiation, the thermal properties of resins remained unaffected.

• International Journal of Safety
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• 제7권1호
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• pp.10-14
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• 2008

For evaluating the radiation degradation of cross-linked polyethylene (XLPE) cable insulation due to the irradiated oxidation, XLPE was irradiated with ${\gamma}$-ray. For each irradiated samples, TGA, DSC, FT-IR, and tensile tests were carried out. Regarding radiation degradation, oxidative process was predominant. TGA, DSC and FT-IR can be useful tools for evaluating the radiation degradation due to the irradiated oxidation because these analyses need only small amount of samples. The results of TGA, DSC and FTIR analyses showed the similar tendency for irradiated degradation. They can be useful tools for evaluating the oxidation of insulating material by non-destructive testing.