• Polymer(Korea)
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• v.32 no.6
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• pp.587-592
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• 2008

High molecular weight poly(vinyl alcohol) (PVA) hydrogel to be expected as a candidate material for the wound-dressing was successfully prepared by electron beam (EB) irradiation. To produce PVA hydrogels with various gel fractions, degrees of swelling in water, gel strengths, and elongations, two different number-average degrees of polymerization [($P_n$)s] of PVA were adapted such as 1700 and 4000, and the PVA solution concentration and irradiation dose of EB were controlled to range of 5 $\sim$ 20% and 30 $\sim$ 100 kGy, respectively. The gel fraction and strength of PV A hydrogel were increased with increasing molecular weight of PVA, solution concentration, and irradiation dose of EB. On the contrary, the degree of swelling and elongation of PVA hydrogel were decreased. The thermal property and crystallinity related to degree of crosslinking of PVA hydrogel were examined by the analyses of differential scanning calorimetry and X-ray diffraction.

• Korean Journal of Food Science and Technology
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• v.34 no.4
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• pp.719-724
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• 2002

Fresh bamboo was charred in the mechanical steel kiln and traditional earth kiln, and then its smoke was condensed to produce bamboo smoke distillates (BSD). BSD made by mechanical steel kiln (MBSD) was purified by distillation. There is significant difference (p<0.05) in total phenol content among them, 663.40 ppm in MBSD, 571.62 ppm in PMBSD, and 485.16 ppm in TBSD. The nitrite scavenging activity and electron donation ability of BSDs were measured and the content of total phenol content was determined. The nitrite scavenging activity of BSD increased with increasing concentration of BSD at the same pH and decreased with increasing pH. There is significant difference (p<0.05) in nitrite scavenging activity among MBSD, purified MBSD (PMBSD), and BSD made by traditional earth kiln (TBSD) and the activity was the highest in MBSD and the lowest in TBSD. The electron donationg ability of BSDs increased with increasing the concentration of BSD and the reaction time. There is significant difference in the electron donation ability of BSDs at the same period and different concentration among the BSDs, the highest in MBSD and the lowest in TBSD.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.4
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• pp.574-580
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• 2003

Optimal extraction conditions for yield, browning color, electron donating ability, nitrite scavenging effect, total polyphenol content and tyrosinase inhibitory activity of Lyophyllum ulmarium were determined by using response surface methodology (RSM) through the central composite design. The extraction yield of Lyophyllum ulmarium was effected by ethanol concentration and browning color was improved with the increase of ethanol concentration than microwave power. The nitrite scavenging effect was improved with the increase of ethanol concentration and decrease of microwave power The electron donating ability, browning color, tyrosinase inhibitory activity and total polyphenol content were improved with the increase in ethanol concentration and microwave power. The optimal ranges of extraction conditions for effective components of Lyophyllim ulmarium were predicted as 60.05~102.75 watt of microwave power, 53.20~64.01% of ethanol concentration and 7.77 min of extraction time.

• Environmental Mutagens and Carcinogens
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• v.15 no.2
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• pp.122-130
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• 1995

In order to evaluate the cytotoxicity of lead in cultures of Balb/c mouse 3T3 cell line, various cytotoxic assays were carried out after expose cells to various concentrations of lead nitrate. Cytotoxic assays using this study were included NR assay, MTT assay, measurement of LDH and protein, synthetic rate of DNA and UDS. Intrace!!ular Ca$^{2+}$ level was also measured. Light and electron microscopic studies were done for morphological changes of lead-treated cell cultures. The results were as follows; 1. The absorbances of NR and MTT were decreased dose-dependently, and NR, and MTT, values of lead nitrate were 3.4 mM and 1.5 mM, respectively. 2. Amount of LDH released into the medium was increased in dose-dependently and LDH activity at 5 mM concentration of lead nitrate was increased to 335 % of control. 3. Amount of total protein was decreased dose-dependently, and which was half of control at 2 mM concentration of lead nitrate. 4. The synthetic rate of DNA was decreased dose-dependently, and also which was remarkably decreased at 3 mM and 5 mM concentrations of lead nitrate. 5. The synthetic rate of UDS was increased at 1 mM concentration of lead nitrate, but which was remarkably decreased at 3 mM and 5 mM concentrations of lead nitrate. 6. Intrace!lular Ca$^{2+}$ level was remarkably increased at 1 mM concentration of lead nitrate, compared with control. 7. In light microscopy, number of cells and processes were decreased according to the increase of dosage of lead nitrate. Electron microscopic findings showed that many vacuoles and cisternal dilatation of rough endoplasmic reticulum were seen in the cytoplasm at 1 mM concentration of lead nittale. From the above results, high dosage treatment of lead nitrate (>3 mM) damaged genetic malerials and it also showed cytotoxicity in mouse 3T3 cell line cultures by injury of cell organelles and Ca$^{2+}$ channel.

• Applied Chemistry for Engineering
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• v.18 no.2
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• pp.173-177
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• 2007

EB irradiation method was used to prepare polyvinyl alcohol (PVA) capped silver nanoparticles under various conditions including PVA concentration, $AgNO_3$ concentration, IPA concentration, and EB dosage. The increase in the distribution of particles size was observed with an increase in the concentrations of PVA, $AgNO_3$, IPA, and EB dosage. $AgNO_3$ concentration, IPA concentration, and EB dosage were found to have a great effect on the amount of silver particles formed in PVA matrix by EB irradiation method. These results were confirmed by XRD, UV, and TEM. XRD (X-ray diffraction) technique confirmed the zero valent state of silver. Optical studies were done using UV-visible spectrophotometer to see the variation of silver particles formed in PVA matrix. Transmission Electron Microscopic (TEM) was employed to show the particle size and distribution of silver foamed in PVA matrix.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.3
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• pp.390-395
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• 2012

Response surface methodology was used to monitor the characteristics of Corni fructus. A maximum electron donating ability of 81.27% was obtained at 119.71 W of microwave power, 7.71% of ethanol concentration, and 4.21 min of extraction time. The maximum inhibitory effect on tyrosinase was 105.92% at 143.36 W of microwave power, 58.19% ethanol concentration, and 6.71 min of extraction time. The maximum superoxide dismutase like activity was 87.08% under the extraction conditions of 107.33 W of microwave power, 96.14% ethanol concentration, and 31.49 min of extraction time. The total polyphenol content showed a maximum of 475.86 mg% at 140.29 W of microwave power, 27.44% ethanol concentration, and 58.69 min of extraction time. Based on the superimposition of four-dimensional RSM data regarding the electron-donating ability, inhibitory effect on tyrosinase, superoxide dismutase like activity, and total polyphenol content, the optimum ranges of extraction conditions were found to be at 78~98 W of microwave power, 3~33% ethanol concentration, and 3.6~9 min of extraction time.

• Journal of the Korean Vacuum Society
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• v.18 no.1
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• pp.73-78
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• 2009

Zinc Oxide (ZnO) nanorods arrays were deposited on ZnO buffered p-Si(100) substrates by hydrothermal method. The ZnO buffer layer with a thickness of 30 nm was deposited by metal oxide chemical vapor deposition at $500^{\circ}C$. The structural and optical properties of ZnO nanorods arrays controlled by precursor concentrations from 0.06 to 0.5 M were studied by FE-SEM(field emission scanning electron microscopy), XRD(X-ray diffraction), and PL(photoluminescence), respectively. It was found that the structural and optical properties of ZnO nanorods arrays are changed significantly with increase of precursor concentration. The sizes of diameter and length of nanorods were increased as the concentration increase, and good optical property was shown with the concentration of 0.3 M.

• JSTS:Journal of Semiconductor Technology and Science
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• v.1 no.4
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• pp.197-201
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• 2001

The influence of argon, oxygen, and nitrogen admixtures on the dissociation of $Cl_2$ molecules in a glow discharge low-temperature plasma under the constant pressure conditions was investigated. For $Cl_2/Ar$ and $Cl_2/O_2$mixtures, the concentration of chlorine atoms was observed to be a practically constant at argon or oxygen concentrations up to 50%. This invariability is a most pro bably explained by relative increase in rate of $Cl_2$ direct electron impact dissociation due to the changes in electrophysical parameters of plasma such as EEDF, electron drift rate and mean energy. For all the considered mixtures, the contribution of stepwise dissociation involving active species from gas additives (metastable atoms and molecules, vibrationally excited molecules) was found to be negligible.

• Parasites, Hosts and Diseases
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• v.50 no.2
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• pp.181-183
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• 2012

The author reported previously on separation of the outer tegument of the spargana (plerocercoids of Spirometra mansoni) using high concentration of urea solution. To determine which layer of the tegument is separated by this method, an electron microscopic analysis has been processed in this study. It was confirmed that the basement layer of the tegument is separated from the parenchyme of the sparganum. In addition, the antigenicity of the separated outer tegument against the human sparganosis patient sera was evaluated. Numerous antigenic proteins, including 16 and 55 kDa proteins, were noticed in the separated tegument; however, there were no diagnostic 31/36 kDa molecules in this tegument. The molecules reactive with the patient sera in the tegument are to be characterized in future studies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.4
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• pp.354-358
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• 2004

In this thesis, an analytical model for Ⅰ-Ⅴ characteristics of an n-AlGaAs/GaAs Delta doped HEMT is proposed. 2-dimensional electron gas density, and conduction band edge profile are calculated from a self-consistent iterative solution of the Poisson equation. Parameters, e.g., the saturation velocity, 2-dimensional electron gas concentration, thickness of the doped and undoped layer(AlGaAs, GaAs, spacer etc.,) are in good agreement with the independent calculations.