• Korean Journal of Materials Research
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• v.24 no.12
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• pp.671-676
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• 2014

It is known that bones get damaged by accidents and aging. Since the discovery of Bioglass, various kinds of ceramics have been also found to bond to living bone; some of these ceramics are already being clinically used as bone-repairing materials. In the present study, antibacterial calcium silicate gel ($Ag-30CaO{\cdot}70SiO_2$ gel) was prepared by sol-gel method in order to control the microstructure, which is related to the dissolution rate and induction period of apatite formation in body environment. In addition, biological $Ag-30CaO{\cdot}70SiO_2$ is tested. This was done to impart antimicrobial activity to the $30CaO{\cdot}70SiO_2$. Ag ion was added during sol-gel synthesis to replace the $H_2O$ added during the making of the $30CaO{\cdot}70SiO_2$ gel, which has silver solutions of various concentration. After the sol-gel process, 1N-$HNO_3$ solution was used to wash the gel when synthesizing the gel, in order to maintain the porous structure and remove PEG, water soluble polymers. Then, the apatite forming ability of the sol-gel derived CaO-$SiO_2$ gels was investigated using simulated body fluid (SBF), which had almost the same ion concentration as that of human blood plasma. The gels were analyzed by FT-IR spectroscopy, SEM observation, XRD, and fluorescent microscopy. The apatite was successfully created even after washing the gel; apatite is present in an amorphous state, and was found to affect the concentration of the Ag ion in cells in MC3T3 live & dead assay results. From these results, it is suggested that a good material that can be used to repair defects of nature bone is $Ag-30CaO{\cdot}70SiO_2$ gel.

• Polymer(Korea)
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• v.29 no.3
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• pp.260-265
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• 2005

The initial burst of drug release is an important role in the controlled delivery of drug having hish toxicity and narrow therapeutic ranges. Nanosphere composed of monolayer could not achieve precisely controlled drug release because of the initial burst of drug on surface. In this study, double layered nanosphere was prepared for sustained drug delivery without initial burst. Double layered nanosphere composed of dextran and PLGA was fabricated by using conventional W/O/W double emulsion method. To control surface tension on the outer layer of nanospheres, PVA was used as a surfactant. Release behavior of dextran as model drug was observed as the $3{\times}1$mm wafers formed by compression mould in the deionized water for 7 days. Double layered nanosphere has sustained release behavior, in contast to single layered nanospheres. such as mechanical mixture and dextran nanospheres. Especially, nanosphere containing PVA $0.2\%$ has shown nearly the zero-order release profile. As a result of this study, double layered nanospheres has more sustained release profile of drug without the initial burst and the release behavior of dexoan on tile double layered nanospheres was controlled by the contents of PVA as a surfactant.

• Polymer(Korea)
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• v.29 no.3
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• pp.266-270
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• 2005

Iron oxide nanoparticles were prepared by the thermal decomposition of iron pentacarbonyl (Fe(CO)$_5$) Poly(vinylpyrrolidone) (PVP) was used as surface-modifying agent to control the size of the iron oxide nanoparticles. The crystalline structure of PVP coated iron oxide nanoparticles was determined by XRD. The size of PVP coated iron oxide nanoparticles was determined by TEM and ELS. The particle sizes of PVP coated iron oxide nanoparticles were controlled by adjusting the molar ratio of PVP/Fe (CO)$_5$, solvent and molecular weight of PVP Particle sizes increased with increasing PVP content. Spherical $50\~100$ nm sized iron oxide nanoclusters were produced when dimethylformamide was used as a solvent. And well-defined 10 nm iron oxide nanoparticles were produced in Carbitol. The prepared PVP coated iron oxide nanoparticles exhibited a well-dispersed property in water. The results obtained in this study confirmed the feasibility of the PVP-coated iron oxide nanoparticles as a biomaterial for MRI contrast agent.

• Polymer(Korea)
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• v.31 no.1
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• pp.14-19
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• 2007

Demineralized bone particle (DBP) has been used as one of the powerful inducers of bone and cartilage tissue specialization. In this study, we fabricated DBP/PLGA scaffold for tissue engineered disc regeneration. We manufactured dual-structured scaffold to compose inner cylinder and outer doughnut similar to nature disc tissue. The DBP/PLGA scaffold was characterized by porosity, wettability, and water uptake ability. We isolated and cultured nucleus pulposus (NP) and annulus fibrosus (AF) cells from rabbit intervertebral disc. We seeded NP cells into the inner core of the hybrid scaffold and AF cells into the outer portion of it. Cellular viability and proliferation were assayed by 3-(4,5-dimethylthiazole-2-yl) -2,5- diphenyltetrazolium -bromide (MTT) test. PLGA and PLGA/DBP scaffolds were implanted in subcutaneous of athymic nude mouse to observe the formation of disc-like tissue in vivo. And then we observed change of morphology and hematoxylin and eosin (H&E). Formation of disc-like tissue was better DBP/PLGA hybrid scaffold than control. Specially, we confirmed that scaffold impregnated 20 and 40% DBP affected to proliferation of disc cell and formation of disc-like tissue.

• Polymer(Korea)
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• v.31 no.4
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• pp.329-334
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• 2007

Osmotic pellet system, which is one of the oral drug delivery systems, has been developed to improve manufacturing process, reduce product cost and other problems of osmotic tablet systems. Osmotic pellet is consisted of water swellable seed layer, drug layer, and membrane layer. Among them, the membrane layer plays an important role in a control of the drug release. In this work, we examined the effect of ratio for Eudragit RL and RS on the drug release behavior. Osmotic pellet with nifedipine as a model drug was easily obtained in a good yield by fluidized bed coater. Osmotic pellet showed round morphology with a range of size $1300{\sim}1500\;{\mu}m$. In the experiment of nifedipine release, the release amount increased with the increase of the ratio of Eudragit. This is due to the fact that Eudragit RL contains more hydrophilic quaternary ammonium group than Eudragit RS. Additionally, the release amount was retarded with increasing the membrane thickness. There are no differences in the release amount measured at the different pH 1.2, 6.5, 6.8, and 7.2. In conclusion, it was found that the drug release from osmotic pellets depended on the composition ratio and coating thickness of membrane layer.

• Journal of Applied Biological Chemistry
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• v.53 no.1
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• pp.21-24
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• 2010

In recent years, many agricultural scientists are studying on eco-friendly farming methods. Among of lots of the methods, the natural insecticides are highly motivated and interested due to their safety and biodegradable issues, and readily available source of bioinsecticides. In this study, the crude extract of custard apple (Annona reticulata L.) seed and its three fractions which were separated based on polarity indexes were examined for their insecticidal activities against Myzus persicae Sulzer and Nilaparvata lugens S.. The crude extract (Aceton/MeOH) showed strong insecticidal activities against both insects at 3.00 mg/mL ($LD_{50}$=0.45mg/mL for M. persicae S. and 1.42 mg/mL for N. lugens S.). Furthermore, simple fractionation with hexane, chloroform, and water lead to increase three-folds insecticidal activity on chloroform fraction ($LD_{50}$=0.13mg/mL for M. persicae S. and 1.14 mg/mL for N. lugens S.). The results suggest that A. reticulata extracts might be used to control for M. persicae effectively.

• Reproductive and Developmental Biology
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• v.35 no.1
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• pp.77-83
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• 2011

One-step dilution and direct transfer would be a practical technique for the field application of frozen embryo. This study was to examine whether Jeju Black Cattle (JBC, Korean Cattle) can be successfully cloned from vitrified and one-tep diluted somatic cell nuclear transfer (SCNT) blastocyst after direct transfer. For vitrification, JBC-SCNT blastocysts were serially exposed in glycerol (G) and ethylene glycol (EG) mixtures [10%, (v/v) G for 5 min., 10% G plus 20% EG (v/v) for 5 min., and 25% G plus 25% EG (v/v) for 30 sec.] which is diluted in 10% FBS added D-PBS. And then SCNT blastocysts were loaded in 0.25 ml mini straw, placed in cold nitrogen vapor for 3 min. and then plunged into $LN_2$. One-step dilution in straw was done in $25^{\circ}C$ water for 1 min, by placing vertically in the state of plugged-end up and down for 0.5 min, respectively. When in vitro developmental capacity of vitrified SCNT blastocyst was examined at 48 h after one-step dilution, hatched rate (56.4%) was slightly lower than that of control group (62.5%). In field trial, when the vitrified-thawed SCNT blastocysts were transferred into uterus of synchronized 5 recipients, a cloned female JBC was delivered by natural birth on day 299 and healthy at present. In addition, when the short tandem repeat marker analysis of the cloned JBC was evaluated, microsatellite loci of 11 numbers was perfectly matched genotype with donor cell (BK94-14). This study suggested that our developed vitrification and one-step dilution technique can be applied effectively on field trial for cloned animal production, which is even no longer in existence.

• BMB Reports
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• v.34 no.2
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• pp.144-149
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• 2001

Antioxidant enzymes, scavengers of the reactive oxygen intermediate (ROI), are involved in numerous defense systems in cells. In the present study, we investigated the effects of the hot-water extracts of two medicinally potent mushrooms (Ganoderma lucidum and Phellinus linteus) on the activity and expression of antioxidant enzymes in vitro and in vivo. The mushroom extracts stimulated the catalase activity in a dose-dependent manner in vitro, whereas the other antioxidant enzymes (such as superoxide dismutase (SOD), glutathione peroxidase (GPx)) were unaffected by the extracts. The catalytic activity of catalase in the liver and brain was significantly increased after the oral treatment of the mushroom extracts (2.5 g/kg) to ICR mice for 2 months. Western blot analysis of the liver and brain tissues revealed that the expression level of catalase in the mice, treated with both mushroom extracts, was significantly increased compared to that of the control mice. However, the level of the SOD expression in the mice treated with the natural product extracts was unchanged under the same experimental conditions. Although the mechanisms for the stimulatory effect of the catalase expression by these extracts remains unclear, these results suggest that the ingredients of the Ganoderma lucidum and Phellinus linteus extracts act as an activator of catalase, and regulate the expression of catalase at the translational or transcriptional level.

• Journal of Sericultural and Entomological Science
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• v.28 no.2
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• pp.1-8
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• 1986

This study was conducted to bring light on inducing factors for non-sprouting occured in the mulberry field of Kyungpook Province in 1983. The results are as follws ; 1. In spring, winter buds were suddenly died during germination, necrosis appeared in pholem and cortex of non-sprouting stem and measles at the bottom of non-sprouting stem. 2. The depth of available of soil was more shallow in the non-sproutiong field than in healthy field. 3. There was no signifioant difference between the healthy field and non-sprouting field in siol PH, the content of organic matter, available phosphorous and exchangeble cations. 4. Available boron content in soil was significantly more in healthy field than in non-sprouting field. 5. Boron content in leaf and bark was significantly lower in the non-sproutiong tree than in the healthy tree. 6. The non-sprouting fields were completely controlled by the application of 6kg/10a borax. 7. Cold tolerance of the mulberry tree was higher in the mulberry tree with boron than in the mulberry tree without boron. 8. Mulberry tree in Kyungpook Province in 1983 may absorb water earlier compared with the average year because of high temperature at the end of March, 1983 and they had been damaged by frost injuary due to the lowest temperature (-6.4$^{\circ}C$) on the grass at the beginning of April 1983. As the above results, non-sprouting bud in the mulberry fields of Kyungpook Province in 1983 had been occured by low temperature and boron deficiency and boron deficiency of mulberry trees accelerared the frost injury.

• Spatial Information Research
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• v.18 no.3
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• pp.1-11
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• 2010

Recently, the construction of three dimensional spatial information of Dam reservoir area is very important part in Dam management work such as sediment survey, but it is difficult to acquire detailed terrain data because totalstation and single beam echo sounder are applied to terrain survey. This study presented method to construct detailed terrain data of Dam reservoir area using LiDAR and multi beam echo sounder. First, LiDAR survey was carried out in land zone and calibration process was applied by ground control point. And also the DEM of land zone was constructed by using algorithm, which eliminated building and vegetation class. As the result of validation of LiDAR DEM using GPS terrain survey, it was possible to construct three dimensional terrain data that was satisfied with the tolerance error of LiDAR, which was the standard error of LiDAR DEM showed as 0.108m. Also multi beam echo sounder was applied to the survey of water zone and it could construct spatial information that was satisfied with bathymetry surveying tolerance error of International Hydrographic Organization by validation with terrain survey data. And LiDAR and multi beam echo sounder data were integrated and it was possible to construct three dimensional spatial imagery information that can be applied to Dam management work such as the estimation of sediment amounts or the monitoring of terrain change by linking with high resolution orthophoto.