• Journal of Radiation Industry
• /
• v.5 no.1
• /
• pp.1-5
• /
• 2011

Since proteomics can be employed to compare changes in the expression levels of many proteins under particular genetic and environmental conditions, using mass spectrometry to establish radiation stimulon, we performed two-dimensional gel electrophoresis and identified E. coli proteins whose expressions are affected by high dose of ionizing radiation. After exposure to 3 kGy, it was found that 6 proteins involved in carbon and energy metabolism were reduced. Although 4 of 7 protein spots showing a significant increase in expression level were neither identified nor classified, uridine phosphorylase (Udp), superoxide dismutase (SodB), and thioredoxin-dependent thiol peroxidase (Bcp) were proven to be up-regulated after irradiation. This suggests that E. coli subjected to high doses of radiation (3 kGy) may operate a defense system that is able to detoxify reactive oxygen species and stimulate the salvage pathway of nucleotide synthesis to replenish damaged DNA.

• Journal of Radiation Industry
• /
• v.3 no.1
• /
• pp.19-24
• /
• 2009

The citrus fruits were irradiated at different doses (25~200 kGy) to remove pesticides such as diuron, dichlorbenil, trifluralin, dimetoate, chlorothalonil, fenitrothion, bromacil, phenthoate and norflurazon, and the rates of degradation were detected by using gas chromatography electron capture detector (GC-ECD). The limit of detection (LOD) was in the range of 0.007~0.105 ppm. The limit of quantification (LOQ) was in the range of 0.024~0.352 ppm, and the recoveries of 9 pesticides were in the range of 71.5~106.5%. The results demonstrated that the ${\gamma}$-irradiation was effective method to remove pesticides such as diuron, dichlorbenil, trifluralin, dimetoate, chlorothalonil, fenitrothion, and norflurazon. However, the bromacil and phenthoate showed lower removal rates in the rate of 40.5 and 54.8%, respectively, at 200 kGy irradiation.

• Journal of Radiation Industry
• /
• v.7 no.2_3
• /
• pp.177-182
• /
• 2013

This study was conducted to evaluate the effect of gamma irradiation on the microbial populations of dried raw materials (9 products) and Saengsik powder. The samples were gammairradiated at doses of 2, 4, 6 and 8 kGy and the microbiological populations were evaluated. The total numbers of bacteria and Bacillus cereus in non-irradiated dried-raw materials for Saengsik powder was 1.3~3.4 and $1.7{\sim}2.4log\;CFU\;g^{-1}$. However, gamma irradiation reduced the microbiological populations in all samples, and Saengsik powder were sterilized at more than 6 kGy. Moreover, Clostridium perfringens were not observed in all samples within detection limit (<$1log\;CFU\;g^{-1}$). Therefore, the results of this study suggest that gamma irradiation at 6 kGy is sufficient to sterilize Saengsik powder, and thus, irradiated Saengsik powder at 6 kGy fulfills the microbiological requirements for sterilized food.

• Journal of Radiation Industry
• /
• v.5 no.1
• /
• pp.25-33
• /
• 2011

Skin contact allergy (SCA) is not life-threatening, but a large number of people have been suffered from the reactions caused by various kinds of chemicals and products. Thus, in this study, radiation technology was employed to improve the traditional herb addition method on the SCA reduction of Rhus verniciflua sap (RVS). Rhus verniciflua has traditionally been used as an herbal medicine plant, but its urushiol derivatives are known as a major allergen for the SCA. The present study was commenced to assess the allergenicity of both gamma-irradiated and non-irradiated RVS by using guinea-pig maximization test (GPMT) in order to probe the mechanism of an SCA. In the acute dermal irritation assays, non-irradiated RVS caused erythema, but the irradiated RVS did not provoke any erythema on the abdominal skin of the guinea pigs. From the result of the GPMT, urushiols, the main chemical components of RVS, were identified as an extreme skin sensitizer, and the removal of urushiols by irradiation extremely reduced the erythema. These results suggest that radiation technology is a novel method to reduce SCA through the removal of urushiols of RVS.

• Journal of Radiation Industry
• /
• v.5 no.2
• /
• pp.107-112
• /
• 2011

Electron beam-induced crosslinking of polycaprolactone (PCL) films containing various crosslinking agents (CAs) was investigated in this study. PCL films containing various CAs prepared by a solution casting method were irradiated by electron beams at various absorption doses and the irradiated PCL films were investigated in terms of their crosslinking degree, thermal and mechanical properties, and biodegradability. Based on the results of the crosslinking degree measurement, triallyl isocyanurate was found to be most effective for the electron-beam induced crosslinking of PCL films. The results of the UTM, DMA, and TMA revealed that the thermal and mechanical properties of the crosslinked PCL films were greatly improved in comparison to those of the pure PCL. The results of the enzymatic degradation test revealed that the biodegradability of the crosslinked PCL films was reduced in comparison to that of the pure PCL.

• Korean Membrane Journal
• /
• v.9 no.1
• /
• pp.52-56
• /
• 2007

A proton exchange membrane was prepared by ${\gamma}-irradiation-induced$ grafting of styrene into poly(tetrafluoro-ethylene-co-perfluoropropyl vinyl ether) (PFA) and subsequent sulfonation reaction. The degree of grafting (DOG) increased with an increase in the absorbed dose. The prepared membranes showed high ion exchange capacity reaching 3.0 meq/g, which exceeded the performance of commercially available perfluorosulfonic acid membranes such as Nafion. The proton conductivity of PFA-g-PSSA membrane increased with the DOG and reached 0.17 S/cm for the highest sample at room temperature. The DMFC performance of the prepared membranes with 50% DOG was comparable to that of Nafion membrane.

• Nuclear Engineering and Technology
• /
• v.53 no.1
• /
• pp.164-171
• /
• 2021

The europium sorption on Tamusu clay was investigated by batch sorption experiments and spectroscopic study under the condition of strong ionic strength. The results demonstrated that europium sorption on Tamusu clay increased rapidly with pH value, but decreased with the ionic strength of solution increased. The europium sorption also increased in the presence of humic acid, especially at low pH value. The sorption could be fitted by Freundlich isotherm model and the europium sorption on clay was spontaneous and endothermic reaction. Besides, the result indicates that ion exchange was the main process at low pH value, while inner-sphere surface complexation dominated the sorption process at high pH value. The Backscatter electron scanning/Energy Dispersive Spectrometer(BSE/EDS) and the effect of Na for europium sorption results further suggested that europium sorption on Tamusu clay mainly competed with Na at low pH value. Overall, the results in this research were of significance to understand the sorption behavior of europium on the geological media under high ionic strength.

• Nuclear Engineering and Technology
• /
• v.49 no.3
• /
• pp.598-608
• /
• 2017

A new radiation scale is proposed. With empathy toward the vast majority of people who are not well versed in radiation and related matters, and thus suffering from misunderstanding that breeds unnecessary fear of radiation, the aim of proposing a new radiation scale, radiation index (RAIN), is to put the general public at ease with the concept of radiation. RAIN is defined in dimensionless numbers that relate any specific radiation dose to a properly defined reference level. As RAIN is expressed in plain numbers without an attached scientific unit, the public will feel comfortable with its friendly look, which in turn should help them understand radiation dose levels easily and allay their anxieties about radiation. The expanded awareness and proper understanding of radiation will empower the public to feel that they are not hopeless victims of radiation. The correspondence between RAIN and the specific accumulated dose is established. The equivalence will allow RAIN to serve as a common language of communication for the general public with which they can converse with radiation experts to discuss matters related to radiation safety, radiation diagnosis and therapy, nuclear accidents, and other related matters. Such fruitful dialogues will ultimately enhance public acceptance of radiation and associated technologies.

• Journal of Applied Biological Chemistry
• /
• v.51 no.1
• /
• pp.28-35
• /
• 2008

The physico-chemical properties of kapok fibers were altered via the combination processes of chlorite-periodate oxidation, in order to assess their efficacy as a heavy metal adsorbent. The chemically-oxidized kapok fibers were found to harbor a certain amount of polysaccharides, together with lowered lignin content. This alteration in lignin characteristics was clearly confirmed via FTIR and NBO yield. Moreover, chemically oxidized kapok fibers retained their hollow tube shape, although some changes were noted. The chemically oxidized kapok fibers evidenced elevated ability to adsorb heavy metal ions with the best fit for the Langmuir adsorption isotherm model. Three cycles of adsorption-desorption were conducted with in-between regeneration steps. Our experimental results indicated that chemically oxidized kapok fibers possessed excellent adsorption characteristics, and the modified kapok fibers could be completely regenerated with almost equimolar diluted sodium hydroxide. Pb, Cu, Cd and Zn ions evidenced adsorption rates of 93.55%, 91.83%, 89.75%, and 92.85% on the chemically oxidized kapok fibers. The regeneration efficiency showed 73.58% of Pb, 71.55% of Cu, 66.87% of Cd, and 75.00% of Zn for 3rd cycle with 0.0125N NaOH.

• Journal of Radiation Industry
• /
• v.4 no.1
• /
• pp.25-31
• /
• 2010

Cooking drips which were obtained as by-product after seafood processing in the food industries, still contain lots of proteins, carbohydrates, and other functional materials. This study was conducted to investigate the effect of gamma irradiation on the biological activities of seafood cooking drips. When the cooking drips of Hizikia fusiformis, Enteroctopus dofleini and Thunnus thynnus were irradiated, the antioxidant activities, whitening effect, and angiotensin I converting enzyme inhibition activity of the ethanol extract from seafood cooking drips were all increased by gamma irradiation. This was because of the increased extraction efficiency of available compounds by irradiation. These results suggested that the seafood cooking drips, wasted as by-products, can be used as functional compounds with gamma irradiation treatment.