• Advances in materials Research
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• v.3 no.4
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• pp.183-197
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• 2014

Copolymers of gelatin and poly (vinyl alcohol), (PVA) grafted by acrylic acid (AAc) with excellent water absorption and retention abilities under neutral conditions were successfully synthesized using $^{60}Co$ gamma radiations in presence of ammonium persulphate (APS), as water soluble initiator and sodium bicarbonate ($NaHCO_3$) as foaming agent. The optimum synthesis conditions pertaining to maximum swelling percentage were evaluated as a function of gelatin/PVA ratio, amount of water, concentration of APS, $NaHCO_3$, monomer concentration and total irradiation dose. Maximum percent swelling (1694.59%) of the copolymer, gelatin-co-PVA, was obtained at optimum $[APS]=2.92{\times}10^{-1}mol/L$, $[NaHCO_3]=7.94{\times}10^{-2}mol/L$ and 1.5 mL of water at total dose of 31.104 kGy while in case of grafted copolymer, (gelatin-co-PVA)-g-poly(AAc), maximum percent swelling (560.86%) was obtained using $8.014{\times}10^{-1}mol/L$ of AAc in 9 mL water with 31.104 kGy preirradiation dose. The pristine and grafted copolymers were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning electron Microscopy (SEM), Thermal gravimetric analysis (TGA) and X-Ray Diffraction (XRD) methods. The copolymers loaded with an antiseptic, Povidone, were used as wound dressing materials for wounded gastrocnemius muscle of mice and the results exhibit that (gelatin-co-PVA)-g-poly (AAc) copolymer is a potent wound dressing material as compared to the copolymer.

• Progress in Medical Physics
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• v.26 no.2
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• pp.99-105
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• 2015

The monitor chamber is a real time dosimetry device for the measurement and the control of radiation beam intensity of the linac system. The monitor chamber prototype was developed for monitoring and controlling radiation beam from the linac based radiation generator. The thin flexible printed circuit boards were used for electrodes of the two independent plane-parallel ionization chambers to minimize the attenuation of radiation beam. The dosimetric characteristics, saturation and linearity of the measured charge, were experimentally evaluated with the Co-60 gamma rays. The performance of the developed monitor chamber prototype was in an acceptable range and this study shows the possibility of the further development of the chamber with additional functions.

• Korean Journal of Food Science and Technology
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• v.5 no.2
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• pp.95-100
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• 1973

In order to study the effect of gamma-ray on the storage stability and quality of polished wheat, the grain was irradiated at $50{\sim}1000$ krad levels and quality assessment was made for three-month storage period. The results are summarized as follows: 1) Growth of molds was apparent at equilibrium moisture content above 14.8% of the grain, but their growth was retarded at 250 krad level. 2) Irradiation at 250 krad level had no adverse effect on fat acidity, reducing sugar content and color of the grain. 3) Irradiation of the grain caused the increase of degree of gelatinization and the decrease of viscosity. 4) Irradiation at 250 krad level brought about higher digestibility of the grain but had no effect on the rate of retrogradation.

• Korean Journal of Environmental Agriculture
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• v.16 no.3
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• pp.216-219
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• 1997

Thirty day old rice seedlings, Ilpoom and Taeback variety, grown under deficient condition of several elements in nutrition solution of sand culture were exposed to 20Gy, 40Gy, 80Gy of gamma ray $(^{60}Co)$ to study the effect of their radiosensitivity. The results obtained are summarized as follows : Plant height and fresh weight of nutrient deficient rice plants were far less than those of control. The effect was different with nutrient element and rice variety, as show increasing effect of radiosensitivity in the Ilpoom variety was high in the Fe deficient whereas that of Taeback was high in the P deficient. Growth inhibition of rice plant irradiated with 20Gy was highly occurred in the Fe and Zn deficient plot in Ilpoom variety and P and Zn deficient plot in Taeback variety. In 80Gy irradiated group, radiosensitivity of rice plant was high in the P and Ca deficient plot of both Ilpoom and Taeback variety.

• Journal of Plant Biotechnology
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• v.30 no.2
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• pp.201-206
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• 2003

Differential responses of red pepper plant and cultured cells to enhanced ${\gamma}$-ray($^{60}$ Co) and ultraviolet(UV) stress were investigated. In seed treatment, 1 Gy of ${\gamma}$-ray increased seedling dry weight up to 19.1%, but 50 Gy treatment markedly ingibited seed germination and subsequent growth of seedling. UV treatment to seed did not change the germination ability of seeds and the growth of seedlings regardless of duration of UV treatment until 24 hrs. In case of UV treatment to seedlings, plant injury was seriously progressed even after the seedlings were returned to no UV condition, and eventually all the leaves showed chlorosis by the stress. However, progress of plant injury by ${\gamma}$-ray stress slower than that caused by UV stress, and even at the high dose of ${\gamma}$-ray 50 Gy, did not caused the cholrosis of stressed plant leaf. Amount of electrolytes leakage from plant leaf by UV treatment for 24hrs was increased up to 28.8 folds in comparison with untreated control, whereas that of 50 Gy of ${\gamma}$-ray was increased only 1.2 folds. UV stress induced the production of capsidiol, antimicrobial phytoalexin, by activation of gene expression involved in capsidiol biosynthesis, such as sesquiterpene cyclase and cyclase and cytochrome P450 hydroxylase in the leaf and cultured cell, but ${\gamma}$-ray stress induced neither the production of capsidiol nor expression of the genes.

• Nuclear Engineering and Technology
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• v.56 no.9
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• pp.3872-3883
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• 2024

This study investigates the effects of Zinc (Zn), Manganese (Mn), and Iron (Fe) additions on the microstructure, corrosion behaviour, biocompatibility, mechanical, and gamma-ray shielding properties of Magnesium (Mg) alloys prepared in various compositions using powder metallurgy (PM). The microstructure and mechanical properties of these alloys were analyzed using electron microscopes (SEM and FE-SEM) and X-ray diffraction (XRD) methods. The results showed positive changes in the material's structure when the percentage of zinc added to pure magnesium increased. It was observed that the material became ductile, and the ductile fracture increased when the zinc ratio increased. The gamma-ray shielding properties of newly produced Mg-based alloys have also been discussed since they have a high potential for use in space technologies. Radiation shielding measurements have been performed using a 3" × 3" NaI(Tl) scintillation detector NaI (Tl) gamma-ray spectrometer. The gamma-ray shielding parameters such as the linear attenuation coefficients (μ_l), mass attenuation coefficient (μ_m), effective atomic number (Z_eff), half-value layer (HVL), and tenth-value layer (TVL) have been determined experimentally at photon energies of 0.511 MeV (emitted from a²²Na radioactive point source) and 1.173 MeV and 1.332 MeV (emitting from a⁶⁰Co radioactive point source). The obtained parameters have been compared to the theoretical results of the XCOM software, and a satisfactory agreement has been found. It can be said from the results that the Mg30Zn alloy has the best shielding properties among the produced materials.

• YAKHAK HOEJI
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• v.37 no.5
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• pp.511-519
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• 1993

The short and variabke transit of drug throught GI tracj and the inter-and intra-subject variations of the transit restrict the sustained drug absorption after oral adminstration. These restrictions may be solved by retaining the dosage forms in the stomach. Then the dosage form will act as a platform which releases the drug slowly and makes the GI absorption occur for a long time. In this study, as the platforms, PVP hydrogels were synthesized by chemical and y-irradiation method in the cylindrical test tube. The chemical method means the synthesis of the hydrogel by heating the mixed solution of N-vinyl-2-pyrrolidone [monomer], acrylated albumin [crosslinking agent], 2, 2'-agobis(2-methylpropionitrile) [initiator] and proxyphylline [drug] at $65^{\circ}C$ for 5 hr. The $\gamma$-irradiation method means the synthesis of the hydrogel by irradiation with $^{60}$ Co $\gamma$-ray of the mixed solution of the monomer, acrylated albumin, and flurbiprofen [drug] at room temperature with total 0.2 Mrad for 3 hr. Our intention is to design the hydrogel tablet (diameter : 1.20 cm, thickness : 0.60 cm) which swells in the gastric fluid after oral administration to such a size that passing through the pylorus could be inhibited during the period of drug release. After releasing drug, the hydrogel should be degraded by the enzymeatic digestion in the stomach, or by hydrolysis and eventually solubilized. Thus, in votro tests were performed to examine the factors that affect swelling and drug release from the PVP hydrogels. Experimental results show that the hydrogels swell to a size larger than the diameter of the pylorus(l.3$\pm$0.7 cm) and the hydrogel prepared by the chemical method is digested by pepsin. But the hydrogel prepared by the $\gamma$-irradiation method was not digested by the pepsin and just collapsed with time. Thus, the swelling of the hydrogel synthesized by $\gamma$-irradiation was independent albumin acrylation time and pepsin concentration. But drug content and radiation dose affected the swelling and drug release kinetics of the hydrogel. Drug release from the hydrigels was prolonged up to about 24 hr. Therefore, it was concluded that by adjusting these factors, the albumin-crosslinked PVP hydrogel synthesized by $\gamma$-irradiation method is expected to be retained in the stomach for up to 60hr and be a potential platform of drugs for long-term GI absorption.

• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.123-131
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• 2018

This study compared PENELOPE with measured values from low energy peak to high energy peak to reduce peak to compton ratio and continuum background spectrum using $^{60}Co$, $^{137}Cs$ and mixed volume source. In addition, the change in backscattering and compton edge efficiency was compared with that of PENELOPE through changes in the vicinity of low energy. The results from the mixed volume source are applied to the soil samples to determine how much the minimum detection limits of the soil samples are reduced in the suppression and unsuppressed mode. The compton suppression of the low energy region of $^{60}CO$ (1,173 keV) was considerable, and the Compton edge RF for the $^{137}Cs$ (661 keV) peak was 2.8. In particular, the $^{60}Co$ source emits coincidence gamma rays of 1,173.2 keV and 1,332.5 keV, so compton inhibition was reduced by approximately 21%. RF of compton edges of 1,173 keV and 1,332 keV emitted from a $^{60}Co$ source was 3.2 and 3.4, and the peak to compton edge ratio was improved to 8: 1. And Compared with Penelope, the uncertainty was well within 2%. In compton unsuppressed mode, MDA values of 661 keV, 1,173 keV and 1,332 keV were 0.535, 0.173 and 0.136 Bq/kg, respectively, but decreased in compton suppressed mode to 0.121, 0.00826 and 0.00728 Bq/kg. Thus, Compton suppressed could reduce the background radioactivity and the radioactivity contained in the detector itself.

• Korean Journal of Veterinary Research
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• v.41 no.2
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• pp.203-210
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• 2001

Here, we compared the effectiveness of 50 MeV($p{\to}RBe^+$) cyclotron fast neutrons versus $^{60}Co$ ${\gamma}$-rays by the apoptotic fragment frequency in both rat peripheral lymphocytes and crypt cells to check a radiobiological endpoint. The incidence of apoptotic cell death was increased in all irradiated groups, and radiation at all doses trigger rapid changes in both crypt cells and peripheral lymphocytes. These data suggest that apoptosis may play an important role in homeostasis of damaged radiosensitive target organ by removing damaged cells. The curve of dose-effect relationship for these data of apoptotic fragments frequencies was $y=0.3+(6.512{\pm}0.279)D(r^2=0.975)$ after neutrons, while $y=0.3+(4.435{\pm}0.473)D+(-1.300{\pm}0.551)D^2(r^2=0.988)$ after ${\gamma}$-rays. In addition, $y=3.5+(118.410{\pm}10.325)D+(-33.548{\pm}12.023)D^2(r^2=0.992)$ after ${\gamma}$-rays in rat lymphocytes. A significant dose-response relationship was found between the frequency of apoptotic cell and dose. These data show a trend towards increase of the numbers of apoptotic cells with increasing dose. Dose-response curves for high and low linear energy transfer (LET) radiation modalities in these studies were different. The relative biological effectiveness (RBE) value for crypt cells was 1.919. In addition, there were significant peaks on apoptosis induction at 4 and 6h after irradiation, and the morphological findings of the irradiated groups were typical apoptotic fragments in crypt cells that were hardly observed in the control group. Thus, apoptosis induction in both crypt cells and peripheral lymphocytes could be a useful endpoint of rat model for studying screening test and microdosimetic indicator to evaluate the biological effects of radiation-induced cell damage.

• Korean Journal of Food Science and Technology
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• v.21 no.1
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• pp.109-119
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• 1989

To improve the storage method of Kimchi, optimum ripening Kimchi for an irradiation treatment(the time of around 0.3% in total acidity of Kimchi) was irradiated by doses of 1, 2, 3 kGy with Co-60 ${\gamma}-radiation$ and stored at $10^{\circ}C$. Total aerobic bacteria increased in the beginning of storage and then decrease slowly as the number of total lactic acid bacteria increased. Total lactic acid bacteria initially loaded by $10^8\;cells/ml$ in Kimchi shortly after irradiation reduced to $10^4-10^6\;cells/ml$ with 1-3 kGy doses and decreased gradually through the whole storage period. The initial load of yeast, $10^3\;cells/ml$, increased steadily during Kimchi storage and led to more than $10^4\;cells/ml$ after 30 days of storage. While it maintained tha the load in 2-3 kGy irradiated groups after 30 days of storage was less than that at the beginning of storage. pH, acidity and volatile acid in the nonirradiated group were 4.0, 0.7% and 0.06%, respectively at the 15th day after storage, but at the 30th day after storage, 2-3 kGy irradiated groups showed different values, 4.1, 0.58-0.63%, and 0.04-0.05%, respectively. The texture(firmness) of Kimchi reduced along with storage time, and 2 kGy irradiated group proved most favourable in its texture during storage. In the sensory evaluation of Kimchi, nonirradiated group was inedible after 15 days of storage, whereas 2-3 kGy irradiated groups could proling the storage-life of Kimchi over 2 times compared with the nonirradiated Kimchi, showing the good sensory quality even after 30 days of storage.