• Polymer(Korea)
• /
• v.32 no.6
• /
• pp.509-515
• /
• 2008

The aminated polypropylene melt blown ion exchange fibers were synthesized with acrylic acid monomer onto polypropylene melt blown fibers by radiation-induced polymerization and subsequent amination. Degree of grafting was increased with increasing the acrylic acid monomer concentration and total dose. The highest degree of grafting was obtained 140% at a monomer concentration of 20 v/v% acrylic acid and total dose of 4 kGy. Optimum condition of Mohr's salt was 5.0 $\times10^{-3}$ M. Degree of amination was increased with increasing degree of grafting. Water content was about 1.5 times higher than that of trunk polymer. The maximum ion-exchange capacity was 7.3 meq/g which was 2$\sim$3 times higher than a commercial ion exchange fiber. The average pore size was decreased and BET surface area was increased in order of PPmb, PPmb- g- AAc and APPmb- g- AAc. The average pore size and BET surface area of synthesised fibers were $366.1\;{\AA},\;3.71m^2/g,\;143.3\;{\AA},\;4.94m^2/g,\;40.97\;{\AA},\;8.98m^2/g$, respectively.

• Radiation Oncology Journal
• /
• v.7 no.2
• /
• pp.205-211
• /
• 1989

From July 1984 to September 1988, 27 patients with limited stage small cell lung cancer were treated with combined modality (combination chemotherapy Plus radiotherapy) at the Department of Therapeutic Radiology in Kyungpook National University Hospital. Of the 27 patients, 19$(70\%)$ achieved a complete response, 6$(22\%)$ a partial response, and 2$(8\%)$ no response. Female, performance status HO, serum enolase level below 30ng/ml, radiation dose over 4500 cGy, and 4 or more cycles of chemotherapy had a favorable effect on the rates of complete response, although there were no statistical differences according to the variables. Median survival time was 10 months and overall 1- and 2-year survival rates were $40,7\%$ and $12.2\%$, respectively. Complete response (p<0.05), performance status HO (p<0.05), 4 or more cycles of chemotherapy (p<0.05), and radiation dose over 4500 cGy had a significantly favorable effect on 2-year survival rate. Prophylactic cranial irradiation or sex had no effect on survival. The results of this study suggest that radiation treatment should be combined with combination chemotherapy in the therapeutic strategy of SCLC of limited stage.

• Radiation Oncology Journal
• /
• v.4 no.2
• /
• pp.99-105
• /
• 1986

Optimal balance between control probability and risk of complication is emphasized even in present time, Although certain incidence of intestinal injury is accepted as an inevitable consequence after abdominopelvic irradiation, these complications still remain as problems. 60 mice were irradiated with 250 kVp orthovoltage x-ray machine and $200rad{\times}5/wk$ regimen. Histpathologic findings of colorectum and the relationship with occult blood test were analyzed and possible tolerable dose which would be safe from permanent complication was also estimated. Followings are the results: Mild mucosal and submucosal edema were observed in 1,000 rad irradiated group. Congestion of small vessels was prominent in 2,000 rad irradiated group and infiltration of inflammatory cells was observed in 3,000 rad irradiated group. Denuded mucosa was observed in 3,000 rad irradiated group. Occult blood test is not a proper indicator for rectal denuding or rectal ulcer, but our results suggest the possibility of using this as a relative scale of intestinal damage. Mitotic figures of crypt cells were observed even in 5,000 rad irradiated group, these suggest that the repair capacity of crypt cells are still functioning.

• Radiation Oncology Journal
• /
• v.38 no.2
• /
• pp.109-118
• /
• 2020

Purpose: Hypofractionated radiotherapy (RT) is becoming a new standard in postoperative treatment of patients with early stage breast cancer after breast conservation surgery. However, data on hypofractionation in patients with advanced stage disease who undergo mastectomy followed by local and regional nodal irradiation (RNI) is lacking. In this retrospective study, we report late-term effects of 3 weeks post-mastectomy hypofractionated local and RNI with two-dimensional (2D) technique in patients with stage II and III breast cancer. Methods: Between January 1990 and December 2007, 1,770 women with breast cancer who were given radical treatment with mastectomy, systemic therapy and RT at least 10 years ago were included. RT dose was 35 Gy/15 fractions/3 weeks to chest wall by two tangential fields and 40 Gy in same fractions to supraclavicular fossa (SCF) and internal mammary nodes (IMNs). SCF and IMNs dose was prescribed at d_max and 3 cm depth, respectively. Chemotherapy and hormonal therapy was given in 64% and 74% patients, respectively. Late-term toxicities were assessed with the Radiation Therapy Oncology Group (RTOG) scores and LENT-SOMA scales (the Late Effects Normal Tissue Task Force-Subjective, Objective, Management, Analytic scales). Results: Mean age was 48 years (range, 19 to 75 years). Median follow-up was 12 years (range, 10 to 27 years). Moderate/marked arm/shoulder pain was reported by 254 (14.3%) patients. Moderate/marked shoulder stiffness was reported by 219 (12.3%) patients. Moderate/marked arm edema was seen in 131 (7.4%) patients. Brachial plexopathy was not seen in any patient. Rib fractures were noted in 6 (0.3%) patients. Late cardiac and lung toxicity was seen in 29 (1.6%) and 23 (1.3%) patients, respectively. Second malignancy developed in 105 (5.9%) patients. Conclusion: RNI with 40 Gy/15 fractions/3 weeks hypofractionation with 2D technique seems safe and comparable to historical data of conventional fractionation (ClinicalTrial.gov Registration No. NCT04175821).

• The Korean Journal of Nuclear Medicine
• /
• v.5 no.2
• /
• pp.19-40
• /
• 1971

Since the iron balance is maintained by regulated intestinal absorption rather than regulated excretion, there have been many reports concerning the factors which may influence the intestinal iron absorption. As the liver is the largest iron storage organ of the body, any hepatocellular damage may result in disturbances in iron metabolism, e,g., frequent co-existence of hemochromatosis and liver cirrhosis, or elevated serum iron level and increased iron absorption rate in patients with infectious hepatitis or cirrhosis. In one effort to demonstrate the influence of hepatocellular damage on intestinal iron absortion, the iron absorption rate was measured in the rabbits whose livers were injured by a single subcutaneous injection of carbon tetrachloride (doses ranging from 0.15 to 0.5cc per kg of body weight) or by a single irradiation of 2,000 to 16,000 rads with $^{60}Co$ on the liver locally. A single oral dose of $1{\mu}Ci\;of\;^{59}Fe$-citrate with 0.5mg of ferrous citrate was fed in the fasting state, 24 hours after hepatic damage had been induced, without any reducing or chelating agents, and stool was collected for one week thereafter. Serum iron levels, together with conventional liver function tests, were measured at 24, 48, 72, 120 and 168 hours after liver damage had been induced. All animals were sacrificed upon the completing of the one week's test period and tissue specimens were prepared for H-E and Gomori's iron stain. Following are the results. 1. Normal iron absorption rate of the rabbit was $41.72{\pm}3.61%$ when 0.5mg of iron was given in the fasting state, as measured by subtracting the amount recovered in stool collected for 7 days from the amount given. The test period of 7 days is adequate, for only 1% of the iron given was excreted thereafter. 2. The intestinal iron absorption rate and serum iron level were significantly increased when the animal was poisoned by a single subcutaneous injection of 0.15cc. per kg. of body weight of carbon tetrachloride or more, or the liver was irradiated with a single dose of 12,000 rads or more. The results of liver function tests which were done simultaneously remained within normal limit except SGOT and SGPT which were somewhat increased. 3. In each case, there has been good correlation between the extent of liver cell damage and degree of increased iron absorption rate or serum iron level. 4. The method of liver damage appeared to make no obvious difference in the pattern of iron deposit in liver. This may be partly due to the fact that tissue specimens were obtained too late, for by this time the elevated serum iron level had returned within normal range and the pathological changes were almost healed. 5. The possible factors and relationship between intestinal iron absorption and hepatic parenchymal cell damage has been discussed.

• Polymer(Korea)
• /
• v.36 no.1
• /
• pp.71-75
• /
• 2012

In this study, silver nanoparticles (AgNPs) have been prepared by using aqueous $AgNO_3$ solution in the poly(vinyl alcohol) (PVA) hydrogels. PVA powders were dissolved in deionized water, and then irradiated by gamma-ray with a radiation dose of 50 kGy to make hydrogels. PVA hydrogels were dipped into 0.01 and 0.05 M $AgNO_3$ solution for 1 h respectively. After that, the swollen hydrogels were irradiated by gamma-ray at various doses to form AgNPs. UV-vis analysis indicated that the concentration of Ag NPs was enhanced by increasing absorbed dose and the concentration of $AgNO_3$. FE-SEM measurements provided further evidence for the successful formation of Ag NPs in PVA hydrogels. Also, the antibacterial effect of PVA hydrogels stabilized AgNPs against Gram-negative bacteria (S.aureus and E.coli) in liquid as well as on solid growth media has been investigated. The AgNPs consolidated in PVA hydrogel networks have an excellent antibacterial effect.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.41 no.5
• /
• pp.505-512
• /
• 2021

A 3D model was developed to calculate the UV intensity of a submerged-type UV disinfection reactor. Numerical experiments were conducted by inputting the design factors of an open channel-type disinfection reactor and a pipe-type disinfection reactor that were installed in an actual sewage treatment plant. The following data were obtained: The average UV intensity of the installed open channel-type reactor and pipe-type reactor was 7.87 mW/cm² and 13.09 mW/cm², respectively; the UV dose reflecting the UV irradiation time and taking into account attenuation effects such as mixing imbalance, lamp aging, temperature, and fouling, was expected to be 21.1 mJ/cm² and 24.8 mJ/cm², respectively, and these values are 5 % and 24 % higher than the target UV dose of 20 mJ/cm², respectively. By using the UV3D model, the optimal lamp position, which maximizes the average UV intensity without changing the size of the disinfection reactor or lamp output power, can be found. In this case, by only adjusting the lamp position, the average UV intensity can be increased by 0.9 % for the open channel-type and 0.5 % for the pipe-type, respectively. A better average UV intensity can be obtained by model simulation. By adjusting the horizontal and vertical ratio of the open channel-type reactor and by moving the lamp position, the average UV intensity can be increased by 7.4 % more than the present case.

• Nuclear Engineering and Technology
• /
• v.54 no.12
• /
• pp.4660-4670
• /
• 2022

Hydroxyurea (HU) is a novel salt-free reductant used potentially for the separation of U/Pu in the advanced PUREX process. In this work, the radiation stability of HU were systematically investigated in solution by examining the effects of the type of rays (α, β, and γ irradiations), the absorbed dose (10-50 kGy), and the HNO₃ concentration (0-3 mol L^-1). The influence degree on HU radiolysis rates followed the order of the absorbed dose > the ray type > the HNO₃ concentration, but the latter two had moderate effects on HU radiolysis products where NH₄⁺ and NO₂^- were found to be the most abundant ones, suggesting that the differences of α, β, and γ rays should be considered in the study of irradiation effects. The radiolysis mechanism was explored using density functional theory (DFT) calculations, and it proposed the dominant radiolysis paths of HU, indicating that the radiolysis of HU was mainly a free radical reaction among ·H, e_aq^-, H₂O, intermediates, and the radiolytic free radical fragments of HU. The results reported here provide valuable insights into the mechanistic understanding of HU radiolysis under α, β, and γ irradiations and reliable data support for the application of HU in the reprocessing of spent fuel.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2021.04a
• /
• pp.27-27
• /
• 2021

Yacon [Samallanthus sonchifolius (Poepp. & Endl.) H. Robinson], a member of Compositae plants, has sweet taste and crisp texture. Unlike other Andean root crops such as potato and sweet potato, the cultivation area of yacon has increased recently, since it is known to have large content of fructooligosaccharides (FOS). Since there are no yacon varieties bred in Korea, we have been trying to create new genetic resources using gamma-ray. The optimal gamma-ray dosage for mutation breeding in yacon was investigated. Crown bud and green bud of yacon were exposed to doses of gamma rays from 20 Gy to 80 Gy, and subsequently planted in a greenhouse. After 50 days of sowing, the survival rates and growth decreased rapidly at doses above 40 Gy, while all of crown bud individuals died above 60 Gy. The median lethal dose (LD50) of crown bud and green bud was 22.4 and 36.6 Gy, and the median reduction doses (RD50) for plant height, fresh weights, and tuberous root weight were 20-40 Gy, respectively. A dose of 20-40 Gy was found to be optimal for mutation breeding in yacon. Considering the growth factors, the optimum doses were determined to be within the range of 20-40 Gy for the selection of useful mutant lines. M2-M3 mutant lines were obtained from 20-60 Gy gamma-ray-irradiated M1 plants through clonal propagation. These mutant lines will be used for the development of a new variety of yacon plant with high FOS and no crack tuberous root.

• Archives of Pharmacal Research
• /
• v.21 no.6
• /
• pp.683-687
• /
• 1998

We have examined in vitro and in vivo radioprotective effects of a well-known thiol-containing compound, dithiothreitol (DTT). The treatment of both 0.5 and 1mM of DTT significantly increased clonogenic survival of ${\gamma}$-ray irradiated Chinese hamster (V79-4) cells. In order to investigate the possible radioprotective mechanism of DTT, we measured gamma-ray induced chromosome aberration by micronucleus assay. In the presence of 0.5mM or 1mM DTT, the frequencies of micronuclei were greatly reduced in all dose range examined (1.5-8 GY). Slightly higher reduction in micronucleus formation was observed in 1mM DTT-treated cells than in 0.5mM DTT-treated cells. In addition, incubation with both 0.5 and 1mM of DTT prior to gamma-ray irradiation reduced nucleosomal DNA fragmentation at about same extent, this result suggests that treatment of DTT at concentrations of 0.5 and 1mM reduced radiation-induced apoptosis. In vivo experiments, we also observed that DTT treatment reduced the incidence of apoptotic cells in mouse small intestine crypts. In irradiated control group 4.4${\pm}$0.5 apoptotic cells per crypt were observed. In DTT-administered and irradiated mice, only 2.1${\pm}$0.4 apoptotic cells per crypt was observed. In vitro and in vivo data obtained in this study showed that DTT reduced radiation-induced damages and it seems that the possible radioprotective mechanisms of action of DTT are prevention of chromosome aberration.