• Electrical & Electronic Materials
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• v.10 no.8
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• pp.756-762
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• 1997

In this paper the change of electrical properties of transformer oil due to electron beam irradiation is investigated. The specimens are produced with a some different dose of 0.5[Mrad], 1[Mrad] and 2[Mard] except for original specimen. The physical properties of each specimen is analyzed by using the FT-IR spectrum. So it is confirmed that carbonyl groups are increased according to the increase of electron beam dose and also that the nitric compounds are disappeared. The magnitude of dielectric dissipation factor appears maximum value by the contribution of dipoles and ions in the low temperature low voltage region and it is stable due to the saturation of carriers in the high temperature high voltage region in the electric conduction characteristics. Volume resistivity is also measured one of original specimen is larger than irradiated specimen.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.2
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• pp.124-127
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• 2004

W/n-GaN Schottky diodes were irradiated with $^{60}Co\;{\gamma}-rays$ to doses up to 315Mrad. The barrier height obtained from current-voltage (I-V) measurements showed minimal change from its estimated initial value of ${\sim}0.4eV$ over this dose range, though both forward and reverse I-V characteristics show evidence of defect center introduction at doses as low as 150 Mrad. Post irradiation annealing at $500^{\circ}C$ increased the reverse leakage current, suggesting migration and complexing of defects. The W/GaN interface is stable to high dose of ${\gamma}-rays$, but Au/Ti overlayers employed for reducing contact sheet resistance suffer from adhesion problems at the highest doses.

• Nuclear Engineering and Technology
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• v.9 no.2
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• pp.65-74
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• 1977

The radiation-induced graft polymerization of acrylic acid onto polyester fabric was investigated with accelerated electron beams as ratiation source at high dose rates. Homopolymerization was suppressed by addition of cations which is known as homopolymerization inhibitor, but this practical advantage was obtained at the expense of grafting efficiency. The rate of grafting (%/sec) was proportional to the 0.82th power of dose rates over the range from 1.6$\times$10$^{6}$ to 10$\times$10$^{6}$ rad/sec. The grafted polyester fabric showed considerable improvement in moisture regain and antistatic properties.

• Radiation Oncology Journal
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• v.4 no.2
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• pp.183-186
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• 1986

In brachytherapy of uterine cervical cancer using the high dose rate remote afterloading system, it is of prime importance to determine the position of the radiation sources and to estimate the irradiation time. However, calculation with manual method is so time consuming and laborious, that authors designed a software as an aid to intracavitary radiotherapy Planning using the personal computer to obtain the precision of treatment without being too complicated for routine use. Optimal source arrangement in combination with dose rate at each specific points and irradiation time can be easily determined using this software in several minutes.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.946-953
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• 1996

The effect of absorbed dose, dose rate, cationic salts and solvent on the grafting yield was evaluated when acrylic acid was grafted onto polypropylene fabric by simultaneous irradiation process. Low dose rate when irradiated with the same absorbed dose led to a high grafting yield. On the other hand, the grafting yield increased with dose rate in case the total irradiation times is equal, and the initial rate of grafting was found to be proportional to be 0.74 power of dose rate. $FeSO_4{\cdot}7H_2O$ was found to be the most effective additive for high grafting yield, while inhibiting homopolymer formation. It was impossible to induce radiation grafting without the addition of the certain amount of salt, but the grafting yield decreased with increasing metallic salt.

• 대한예방의학회:학술대회논문집
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• 1994.02a
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• pp.431-438
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• 1994

As currently conducted, standard rodent bioassays do not provide sufficient information to assess carcinogenic risk to humans at doses thousands of times below the maximum tolerated dose. Recent analyses indicate that measures of carcinogenic potency from these tests are restricted to a narrow range about the maximum tolerated dose and that information on shape of the dose-response is limited in experiments with only two doses and a control. Extrapolation from high to low doses should be based on an understanding of the mechanisms of carcinogenesis. We have postulated that administration of the maximum tolerated dose can increase mitogenesis which, in turn. increases rates of mutagenesis and, thus, carcinogenesis. The animal data are consistent with this mechanism, because about half of all chemicals tested are indeed rodent carcinogens, and about 40% of the positives are not detectably mutagenic. Thus, at low doses where cell killing does not occur, the hazards to humans of rodent carcinogens may be much lower than commonly assumed. In contrast, for high-dose exposures in the workplace, assessment of hazard requires comparatively little extrapolation. Nevertheless. permitted workplace exposures are sometimes close to the tumorigenic dose-rate in animal tests. Regulatory policy to prevent human cancer has primarily addressed synthetic chemicals, yet similar proportions of natural chemicals and synthetic chemicals test positive in rodent studies as expected from an understanding of toxicological defenses, and the vast proportion of human exposures are to natural chemicals. Thus, human exposures to rodent carcinogens are common. The natural chemicals are the control to evaluate regulatory strategies, and the possible hazards from synthetic chemicals should be compared to the possible hazards from natural chemicals. Qualitative extrapolation of the carcinogenic response between species has been investigated by comparing two closely related species: rats and mice. Overall predictive values provide moderate confidence in interspecies extrapolation; however, knowing that a chemical is positive at any site in one species gives only about a 50% chance that it will be positive at the same site in the other species.

• Progress in Medical Physics
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• v.14 no.3
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• pp.175-183
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• 2003

Absorbed dose dosimetry protocols of high energy photon and electron beams, which are widely used and based on an air kerma (or exposure) calibration factors, have somewhat complex formalism and limitations for improving dosimetric accuracy due to the uncertainty of the physical parameters used. Recently, the IAEA and the AAPM published the absorbed dose to water-based dosimetry protocols(IAEA TRS-398 and AAPM TG-51). The dose calibration programs for these two protocols were developed. This program for high energy photon and electron beams was also developed for users to use in a window environment using the Visual C++ language. The formalism and physical parameters of these two protocols were strictly applied to the program. The tables and graphs of the physical data, and the information of ion chambers were numericalized for their incorporation into a database. This program can be useful in developing new dosimetry protocols in Korea.

• Toxicological Research
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• v.34 no.2
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• pp.85-95
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• 2018

The term Butterfly tea refers to decoction of Mariposa christia vespertilionis leaves which is widely consumed by cancer patients throughout Malaysia and has gained a huge popularity among Malaysians, not only cancer patients but also researchers to discover the real potential of this plant. Herein, the study is aimed at evaluating the possible toxicity in 28-day subacute oral toxicity of ethanolic extract M. christia vespertilionis in male Sprague Dawley rats. The 28-day subacute toxicity study was conducted to detect the no-observed adverse effect level (NOAEL). In this study, a total of 30 rats were divided into the control, 5% DMSO (vehicle), low dose (75 mg/kg), medium dose (125 mg/kg) and high dose (250 mg/kg) groups. The extract was administered daily from day 1 until day 28. At the end of the study, the animals were humanely sacrificed and assessed for the effect extract of Mariposa christia vespertilionis leaves on body weight and relative organ weights and haematological, biochemical and histopathological parameters. The haematological and serum biochemical parameters for the assessment of kidney and liver injuries were carried out. Results of haematological and serum biochemistry results showed no changes in the control and treated groups. In the histopathology, evaluation of kidney tissues in all treated groups showed no significant (p > 0.05) lesions. In contrast to kidney, liver tissues showed significant differences (p < 0.05) in lesions observed in low dose (430 mg), medium dose (700 mg) and high dose (1480 mg) groups with very mild, mild and mild to moderate lesion of hepatic necrosis, in the respective groups, and very mild hepatic degeneration and hepatitis were scored in all three groups.

• Journal of Pharmaceutical Investigation
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• v.36 no.6
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• pp.363-369
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• 2006

Granisetron is a selective 5-HT3 receptor antagonist that is used therapeutically for the prevention of vomiting and nausea associated with emetogenic cancer chemotherapy. Although this drug is commercially available for intravenous and oral dosage, there is a need for intranasal delivery formulations in specific patient populations in which the use of these dosage forms may be unfeasible and/or inconvenient. A rapid and specific high-performance liquid chromatography method with mass spectrometric detection(LC-MS) was developed and validated for the analysis of granisetron in plasma after nasal administration in rats. This method has been validated for concentrations ranging from 5 to 1000 ng/ml with simple treatment. This technique has high level reproducibility, accuracy, and sensitivity. The method described was found to be suitable for the analysis of all samples collected during preclinical pharmacokinetic investigations of granisetron in rats after nasal administration. This study was aimed to investigate the feasibility of nasal delivery of granisetron for the elimination of vomiting. The effects of osmolarity, dosage volume at the same dose and applied dose on the nasal absorption of granisetron in rats were observed. No significant difference in the effect of osmolarity and dosage volume at the same dose was observed. As the applied dose of granisetron in nasal formulation increased, the absorption increased linearly. Based on these results it appears that only the applied dose(drug mass) determines the nasal absorption of granisetron. The bioavailability of granisetron on nasal administration of 4 mg/kg appeared to be comparable to that of intravenous administration of the same dose. These results suggest that granisetron can be efficiently delivered nasally and the development of nasal formulation will be feasible.

• Journal of Physiology & Pathology in Korean Medicine
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• v.34 no.6
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• pp.355-361
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• 2020

This study was designed to assess the toxicity of capsaicin-containing (CP) pharmacopunture using an in vitro chromosomal aberrations in Chinese hamster lung (CHL/IU) cells. In order to determine the high dose level in the main study of this study, a dose range finding study was conducted first. The high dose was selected at 10.0% of CP pharmacopuncture extract, and then diluted sequentially to produce lower dose levels of 5.00, 2.50, 1.25, 0.625 and 0.313% by applying a geometric ratio of 2. As a result, the cytotoxicity and precipitation of the CP pharmacopuncture as a test substance were not evident at any dose level during short-time treatment with and without metabolic activation and continuous treatment without metabolic activation. Therefore, the dose levels for this study were chosen as 10.0, 5.0, and 2.5%., and the treatment volume was 1.3 mL. In addition, negative and positive controls were set. In main study, the frequency of cells with chromosome aberrations in CP treated groups was less than 5% in short-time treatment with and without metabolic activation and continuous treatment without metabolic activation. In addition, there was no statistically significant difference when compared to the negative control group. The frequency of cells with structural chromosomal aberrations in the positive control group was more than 10% compared to the negative control group, and it increased statistically significantly. In conclusion, under the conditions of this study, CP pharmacopuncture did not show the possibility of causing chromosome aberrations.