• Journal of Radiation Industry
• /
• v.6 no.2
• /
• pp.153-158
• /
• 2012

In this research, poly(acrylic acid) (PAAc) hydrogels containing zinc oxide particle were prepared by gamma-ray irradiation. PAAc powder was completely dissolved in distilled water at room temperature. Water-insoluble zinc oxide powder were added into the PAAc solution and stirred until totally dissolved. Finally, the mixture was irradiated by gamma-ray irradiation to make crosslinking. The effects of various parameters such as zinc ions' concentration, irradiation doses were varied and investigated in detail. PAAc hydrogels containing zinc oxide particle were characterized by gel content and swelling ratio. Moreover, the antibacterial properties of this material were evaluated by paper diffusion test against the Gram positive and Gram negative bacteria.

• Journal of Photoscience
• /
• v.1 no.1
• /
• pp.9-14
• /
• 1994

Exposure of isolated intact mitochondria to near UV to visible light resulted in not only loss of respiration, the most well-documented phenomenon regarding phototoxic effects in the respiring organelles, but also lipid peroxidation of membranes and mitochondrial swelling; these turned out to be O$_2$-dependent and thus prevented by anaerobiosis, enhanced by a partial deuteration of the suspension medium, and suppressed by the presence of a singlet oxygen ($^1O_2$) scavenger. Measurements of the spectral dependence of such detrimental effects of light on mitochondrial structure and function revealed that all the resulting spectra bear a significant resemblance to the action spectrum for photogeneration of $^1O_2$ from mitochondrial membranes, which in turn carries the spectral characteristics of light absorption by mitochondrial Fe-S centers. Futhermore, destructing the Fe-S centers by a mercurial treatment of mitochondria brought about a striking reduction of the light-induced membrane peroxidation and swelling of mitochondria. These results are consistent with the suggestion that the impairment of functional, structural integrity of mitochondria caused by strong irradiation is directly related to the production of $^1O_2$ in mitochondria, photosensitized by the Fe-S centers. This paper also presents kinetic data which indicate that, among various membrane-bound protein systems associated with mitochondrial energy metabolism, the respiratory chain is the primary target for photodamage.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.35 no.1
• /
• pp.104-108
• /
• 2006

Effect of gamma irradiation on the softening of dried fernbrake at different moist-heating conditions was investigated. Dried fernbrake packaged in controlled atmosphere $(CO_2\;25\%,\;N_2\;75\%)$ was irradiated up to 7 kGy with $\gamma-ray$. Hardness of dried fernbrake was significantly decreased at the irradiation dose of above 5 kGy. Hardness of cooked fernbrake was significantly decreased with increasing irradiation dose level as well as heating temperature and time. $DT_{50}$ value (The heating time required to reach the $50\%$ reduction of hardness) for irradiated fernbrake was shortened according to dose level as well as heating temperature and heating time: $DT_{50}$ value of control: 23 min, 5 or 7 kGy: $2.2\~5.0$ min at $60^{\circ}C$. Also, the activation energy for softening of irradiated fernbrake ($1.85\~1.88$ kcal/mole for $5\~7kGy$) decreased compared to control (4.30 kcal/mole). Moisture content, swelling and rehydration rate of gamma irradiated fernbrake during moist heating increased according to the irradiation doses. Sensory results showed that scores of off-flavor and odor in irradiated fernbrake upto 7 kGy were not significantly different from control. Based on these results, gamma irradiation was effective for the reduction of cooking time and the activation energy for softening of dried fernbrake with increasing dose levels.

• Nuclear Engineering and Technology
• /
• v.13 no.4
• /
• pp.245-253
• /
• 1981

The properties of polyethylene materials exhibit good insulation and radiation resistance, but exhibit poor flame resistance. Flame retardant properties of the polyethylene were improved by the radiation induced grafting or crosslinking. When the various flame retardants were fixed onto polyethylene, the amount of fixation in grafting was increased with the increase of radiation dosages. In the case of grafting, it is necessary for high grafting yield that the polyethylene films were swelled before irradiation with ${\gamma}$-rays or electron beams. It is the suitable method for the fixation of flame retardant that polyethylene samples were blended with various flame retardants at 1$25^{\circ}C$ and then blended polymers were crosslinked by the electron beams at room temperature.

• Nuclear Engineering and Technology
• /
• v.46 no.2
• /
• pp.125-146
• /
• 2014

This review aims to provide a synthesis of the knowledge generated and the lessons learned in roughly 15 years of UMo dispersion fuel R&D in Europe through a series of irradiation experiments. A lot of irradiations were also performed outside of Europe, particularly in the USA, Russia, Canada, Korea and Argentina. In addition, a large number of out-of-pile investigations were done throughout the world, providing support to the understanding of the phenomena governing the UMo behaviour in pile. However, the focus of this article will be on the irradiations and Post-Irradiation Examination (PIE) results obtained in European experiments. The introduction of the article provides a historic overview of the evolution and progress in the high density UMo dispersion fuel development. The ensuing sections then provide further details on the various phases of the development, from the UMo dispersion in a pure Al matrix through the addition of Si to the matrix to address the interaction layer formation and finally to the more advanced solutions to the excessive swelling encountered in various experiments. This review was based only on published results or results that are currently in the process of being published.

• Nuclear Engineering and Technology
• /
• v.28 no.3
• /
• pp.229-246
• /
• 1996

A mechanistic model has been developed to predict the release behavior of fission gas during steady-state irradiation of LWR UO$_2$ fuel. Under the assumption that UO$_2$ grain surface is composed of fourteen identical circular faces and grain edge bubble can be represented by a triangulated tube around the circumference of three circular grain faces, it introduces the concept of continuous formation of open grain edges tunnels that is proportional to grain edge swelling. In addition, it takes into account the interaction between the gas release from matrix to grain boundary and the reintroduction of gas atoms into the matrix by the irradiation-induced re-solution of grain face bubbles. It also treats analytically the behavior of intragranular, intergranular, and grain edge bubbles under the assumption that both intragranular and intergranular bubbles are uniform in both radius and number density. Comparison of the present model with experimental data shows that the model's prediction produces reasonable agreement for fuel with centerline temperatures of 1000 to 140$0^{\circ}C$, wide scatter band for fuel with centerline temperatures lower than 100$0^{\circ}C$, and underprediction for fuel with centerline temperatures higher than 140$0^{\circ}C$.

• Journal of Radiation Industry
• /
• v.2 no.1
• /
• pp.1-7
• /
• 2008

Active polymer gels expand and contract in response to certain environmental stimuli, such as the application of an electric field or a change in the pH level of the surroundings. This ability to achieve large, reversible deformations with no external mechanical loading has generated much interest in the use of these gels as biomimetic actuators and artificial muscles. In this study, poly (vinyl alcohol)(PVA) grafted acrylic acid monomer (PVA-g-AAc) hydrogels were prepared by $^{60}Co$ ${\gamma}-ray$ irradiation and their properties such as degree of grafting and weight swelling in electrostimulation as an artificial muscle and actuator were investigated.

• Applied Microscopy
• /
• v.36 no.2
• /
• pp.109-118
• /
• 2006

The physicochemical properties of damaged hair by irradiation of ultraviolet-B (UV-B) have been investigated by using transmission electron microscope and scanning electron microscope. The range of irradiation of hair irradiated for expectative 6 hours, 12 hours, 24 hours and 48 hours with stimulated ultraviolet ray. The treated hairs showed characteristic morphological damage pattern in the cornified cell of matrix and the cuticle following time past. The various sized vacuoles in the endocuticle of the cuticular cells was formed. The statistically significant differences in diameter of cuticular cell were observed in terms of tranverse swelling by formation of vacuoles. The hair cortex and matrix undergo long term exposure to UV-B radiation. The macrofibrils of cortex appeared to be affected most by UV-B, although the morphology and volume of melanin granule was not changed. The physicochemical destruction of hair matrix and cuticular cells is largely accelerated by long term irradiation of UV-B.

• Korean Journal of Food Science and Technology
• /
• v.34 no.6
• /
• pp.1007-1012
• /
• 2002

Physicochemical and organoleptic properties were investigated in starch extracted from acorn gamma-irradiated for insect control. Hunter's color L, a, and b values were unchanged upon irradiation at 0.25 to 10 kGy. Scanning electron microscopic observation revealed no changes with gamma irradiation at 1 kGy, that is effective for disinifestation, whereas 10 kGy resulted in some clefts on the starch surface. X-ray diffraction analysis showed patterns of both amorphous and crystalline regions were not different among the treatment groups. Water-binding property, swelling power, solubility, and gelatinization patterns of starch were influenced by irradiation dose, but 1 kGy dose was not detrimental to the physicochemical properties. Textural parameters of acorn gel were relatively stable, but significant reductions were found in hardness, adhesiveness, and chewiness in samples irradiated at 3 kGy or higher. Rrsults revealed that irradiation at 1 kGy or lower could be applied for insect control without causing apparent changes in physicochemical and organoleptic properties of acorn starch.

• Nuclear Engineering and Technology
• /
• v.49 no.5
• /
• pp.1044-1062
• /
• 2017

The construction project of the Kijang research reactor (KJRR), which is the second research reactor in Korea, has been launched. The KJRR was designed to use, for the first time, U-Mo fuel. Plate-type U-7 wt.% Mo/Al-5 wt.% Si, referred to as U-7Mo/Ale5Si, dispersion fuel with a uranium loading of $8.0gU/cm^3$, was selected to achieve higher fuel efficiency and performance than are possible when using $U_3Si_2/Al$ dispersion fuel. To qualify the U-Mo fuel in terms of plate geometry, the first miniplates [HANARO Miniplate (HAMP-1)], containing U-7Mo/Al-5Si dispersion fuel ($8gU/cm^3$), were fabricated at the Korea Atomic Energy Research Institute and recently irradiated at HANARO. The PIE (Post-irradiation Examination) results of the HAMP-1 irradiation test were analyzed in depth in order to verify the safe in-pile performance of the U-7Mo/Al-5Si dispersion fuel under the KJRR irradiation conditions. Nondestructive analyses included visual inspection, gamma spectrometric mapping, and two-dimensional measurements of the plate thickness and oxide thickness. Destructive PIE work was also carried out, focusing on characterization of the microstructural behavior using optical microscopy and scanning electron microscopy. Electron probe microanalysis was also used to measure the elemental concentrations in the interaction layer formed between the U-Mo kernels and the matrix. A blistering threshold test and a bending test were performed on the irradiated HAMP-1 miniplates that were saved from the destructive tests. Swelling evaluation of the U-Mo fuel was also conducted using two methods: plate thickness measurement and meat thickness measurement.