• Journal of the Korean Ceramic Society
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• v.13 no.1
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• pp.35-44
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• 1976

The effect of quartz which exists in clays, especially in kaolin used for the production of chamotte sagger, on the strength of refractory was examined. In this study, a mixture of chamotte 50%, kaolin 25%, plastic clay 25% in ternary component system was selected as a batch composition. To this mixture 1%, 3% and 5% of feldspar and sericite were added respectively. The plastic clay used here was separated under 170 mesh by dry process. Feldspar and sericite were separated under 325 mesh by dry process. Feldspar and sericite were separated under 325 mesh by dry process. In order to change the particle size and the content of quartz, the kaolin was separated under 60, 115, 170 and 325 mesh by wet process, substituted quartz for coarse parts of it. Chamotte was classified into three grades, coarse (5-10mesh): medium (10-20mesh): fine(20-115mesh) and the ratio was 1:1:1. Samples were formed in 0.8xIx10cm size with 12.5% water at 160kg/$\textrm{cm}^2$ pressure, and fired at 130$0^{\circ}C$ for 1 hr. The fired samples were ivnestigated by means of x-ray diffraction analysis and microscopic observation, and the physical properties of them were also examined, such as firing shrinkage, apparent specific gravity and bulk specific gravity, apparent porosity, water absorption and modulus of rupture. The obtained results are as follows: 1. When screened kaolin with low content of quartz was added to fixed chamotte-plastic clay system, the sample lowered modulus of rupture and increased apparent porosity as the size of kaolin became finer. 2. When kaolin under 325 mesh with 7.2-15.81% quartz between 60-325 mesh was added to fixed chamotte-plastic clay system, the sample had higher apparent porosity and lower modulus of ruputure as the size and the amount of quartz became larger. 3. The addition of feldspar and sericite to chamotte-plastic clay system improved apparent porosity and modulus of rupture. The effect of feldspar was better when quartz content was low, although that of sericite was better than quartz content was high.

• Journal of Technologic Dentistry
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• v.34 no.4
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• pp.345-352
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• 2012

Purpose: The age-hardening mechanism of an Au-Ag-Cu-Pt-Zn alloy for crown and bridge fabrication was investigated by means of hardness test, X-ray diffraction study and field emission scanning electron microscopic observation. Methods: Before hardness testing, the specimens were solution treated and then were rapidly quenched into ice brine, and were subsequently aged isothermally at $400-450^{\circ}C$ for various periods of time in a molten salt bath and then quenched into ice brain. Hardness measurements were made using a Vickers microhardness tester. The specimens were examined at 15 kV using a field emission scanning electron microscope. Results: By the isothermal aging of the solution-treated specimen at $450^{\circ}C$, the hardness increased rapidly in the early stage of aging process and reached a maximum hardness value. After that, the hardness decreased slowly with prolonged aging. However, the relatively high hardness value was obtained even with 20,000 min aging. By aging the solution-treated specimen, the f.c.c. Au-Ag-rich ${\alpha}_0$ phase was transformed into the Au-Ag-rich ${\alpha}_1$ phase and the AuCu I ordered phase. Conclusion: The hardness increase in the early stage of aging process was attributed to the formation of lattice strains by the precipitation of the Cu-rich phase and then subsequent ordering into the AuCu I-type phase. The decrease in hardness in the later stage of aging process was due to the release of coherency strains by the coarsening of tweed structure in the grain interior and by the growth and coarsening of the lamellar structure in the grain boundary. The increase of inter-lamellar space contributed slightly to the softening compared to the growth of lamellar structure toward the grain interior.

• Journal of Periodontal and Implant Science
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• v.23 no.2
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• pp.283-299
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• 1993

The purpose of this study was to observe early connective tissue attachment on dentin surface treated with citric acid, tetracycline, and fibrin sealants and compare their conditioning effects on dentin surface. Experimental dentin blocks conditioned with citric acid, tetracycline or fibrin sealant, and only root planned control block were surgically implanted in the pouch under buccal mucoperiosteal flaps of left mandible, right maxilla, left maxilla, right mandible of 18 male rabbits. Rabbits were sacrificed after 1 and 6 hours, 1, 3, 7 and 14 days after implantation and then specimens including dentin block and surrounding soft tissue were obtained, and prepared for light and transmission electron microscopic examination. 1 and 6 hours after dentin block implantation, there was plasma proteins adsorption followed by fibrin clot formation and no differences among specimens. At the 1-day observation interval, delicate fibrin network was observed in the all groups, and there were proliferative fibroblasts, angiogenesis and macrophage in the all 3-day specimens. Cellular aggregates and abundant connective tissue adhered dentin surface and tetracycline or citric acid treated group showed much proliferative fibroblast and abundant collagen fibers at 1 week. But at 2 week, citric acid treated group showed much proliferative fibroblast and abundant collagen fibers. These observations suggested that new connective tissue attachment to dentin was initiated by the adsorption of plasma proteins to the dentin surface and followed by fibrin clot formation. Tetracycline and citric acid seemed to make dentin surface more biologically favorable for the connective tissue attachment.

• BMB Reports
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• v.41 no.2
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• pp.119-125
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• 2008

Our previous work confirmed that Sph2/LA1029 was a sphigomyelinase-like hemolyisn of Leptospira interrogans serogroup Icterohaemorrhagiae serovar Lai. Characteristics of both hemolytic and cytotoxic activities of Sph2 were reported in this paper. Sph2 was a heat-labile neutral hemolysin and had similar hemolytic behavior as the typical sphingomyelinase C of Staphylococcus aureus upon sheep erythrocytes. The cytotoxic activity of Sph2 was shown in mammalian cells such as BALB/C mouse lymphocytes and macrophages, as well as human L-02 liver cells. Transmission electron microscopic observation showed that the Sph2 treated BALB/C mouse lymphocytes were swollen and ruptured with membrane breakage. They also demonstrated condensed chromatin as a high-density area. Cytoskeleton changes were observed via fluorescence confocal microscope in Sph2 treated BALB/C mouse lymphocytes and macrophages, where both cytokine IL-$1{\beta}$ and IL-6 were induced. In addition, typical apoptotic morphological features were observed in Sph2 treated L-02 cells via transmission electron microscope and the percentage of apoptotic cells did increase after the Sph2 treatment detected by flow cytometry. Therefore, Sph2 was likely an apoptosis-inducing factor of human L-02 liver cells.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.3
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• pp.199-206
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• 1982

Histological changes occurred by freezing storage and subsequent thawing, and changes of muscle fiber after heating and drying of the eel (Anguilla japonica) were observed under microscope . The results are as follows : (1) After one month of freezing storage the muscular tissue produced considerable number of extracellular and intracellular ice crystals. The sample stored at the temperature of $-40^{\circ}C$ produced ice crystals inside the muscle cells while sample stored at $-20^{\circ}C$, outside. (2) No changes were observed in the hypodermic fat after thawing regardless of storage temperature, while insufficient recovering of muscle cells were detected in the muscular tissue. Muscular tissues which have been stored $-20^{\circ}C$ showed severe change in shape due to dehydration. (3) Microscopic observation on muscle homogenate showed loss of transparency due to free-zing, disfiguration and contraction by drying and water seperation, and elasticity by heating.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.2
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• pp.1003-1007
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• 2013

Objective: This work aimed to investigate the correlations of tumor-associated macrophages (TAMs) and their subtypes M1 and M2 with liver metastasis of colorectal cancer, and provide useful references for seeking predictors of liver metastasis and studying mechanisms. Methods: 120 patients with colorectal cancer from 2000 to 2009 were divided into low, middle and high liver metastasis groups (group A, B and C, respectively). S-P immunohistochemical staining and microscopic observation were conducted to compare expression in CD68-positive cells (TAMs), CD80-positive cells (M1) and CD163-positive cells (M2) in three groups. Correlations of TAMs, M1, M2, and M2/M1 ratio with clinical and pathological parameters were analyzed. Results: With increase of liver metastatic ability, the number of TAMs decreased gradually, with no significant difference between any two of the three groups (P > 0.05), while the numbers of M1 and M2 were significantly decreased and increased, respectively, with significant difference between any two of three groups (P < 0.05 or P < 0.01). In addition, the M2/M1 ratio increased with increase of liver metastatic ability (P < 0.01). There was no statistical significance of correlation of TAMs with each clinical and pathological parameter. M1 was negatively related with lymphatic metastasis and liver metastatic ability. M2 was positively correlated with preoperative CEA level, lymphatic metastasis, tumor differentiation degree and liver metastatic ability. The same was the case for the M2/M1 ratio. Conclusions: Effects of TAMs on liver metastasis of colorectal cancer do not depend on the total number of TAMs, but on the number and proportion of functional subtypes M1 and M2. M2 number and M2/M1 ratio are more accurate predictors for liver metastasis of colorectal cancer.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.13 no.4
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• pp.370-380
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• 1991

This article is intended to study histopathological and immunohistochemical response after autogenous full-thickenss skin graft in rat. 12 male Sprague-Dawley rats were used as the experimental animals. A $1Cm{\times}1Cm$ skin(0.7mm diameter) was taken on the right inguinal area of the rat. Another full-thickeness skin graft($1Cm{\times}1Cm$) was taken from the left inguinal area of the rat. And it was transplanted to the right inguinal area of the rat. The left side wound was closed directly. Light microscopic observation was made at the postoperative $1^{\circ}3^{\circ}8^{\circ}16$ day, after the hematoxylin - Eosin staining of the 4u-thick paraffin embedded specimens and the immunoshitochemical staining of the 10u-thick frozen specimens with mouse anti-rat monoclone antibodies and ABC staining kit. The results were as follows. 1. Electromicroscopic studies revealed interstitial tissue bleeding of transplanted autogenous skin. The response was severe in the 1 day group after operation, moederate in 3 day group, mild in 8 day group, and almost resovled in the 16 days group. 2. Electromicrospic studied also revealed a mild monocyte response in the 3 day and 8 day group. A histiocytic infiltrate was observed. There was a mild response in the 3 day group and moderate response in the 8 day group. 3. Immunohistochmically studies revealed a few pan T cells in the 1 day group, mild appearance of pen T cells and cytotoxic T cells in the 3 day group, a moderate infiltrate of pan T cells and helper T cells in the 8 day group, and total resolution of pan T cells in the 16 day group. 4. According to these finding, a strong inflammatory response was observed around transplanted autogenous skin in the 3 & 8 day groups. In the 16 day group this response had resolved histopathologically and immunohistologically.

• The Korea Journal of Herbology
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• v.31 no.4
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• pp.71-77
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• 2016

Objectives : Adipogenesis was defined as a differentiation process of preadipocytes into the adipocytes. Thus, to control of this process can be one of the most important strategies to prevent obesity. Korean ginseng(Panax ginseng C.A. Meyer) is one of the most widely used medicinal herbs. Although multiple biological activities of Korean ginseng, particularly ginsenosides, have been known, the anti-adipogenic role and function of polysaccharides from Korean ginseng are still unclear. In this study, we examined anti-adipogenic activity of polysaccharides and its molecular basis mechanisms are further investigated.Methods : The cytotoxicity of KGP in 3T3-L1 was evaluated by MTT assay. Anti-adipogenic effect of KGP was examined by Oil Red O (ORO) staining and microscopy observation in 3T3-L1 mature adipocytes. The mRNA expression levels of adipogenic transcriptional factors were analyzed by reverse transcription-polymer chain reaction (RT-PCR). To elucidate the adipogenic molecular mechanism of KGT, SB431542 (TGF-β specific inhibitor) was used.Results : We found that polysaccharides showed no effect on the viability of 3T3-L1 preadipocytes. Dose dependent inhibitory effect of polysaccharides on 3T3-L1 adipogenesis was observed as judged by ORO staining and microscopic image analysis. To obtain further mechanistic insight into anti-adipogenic function of polysaccharides, we then tested the effect of polysaccharides treatment on the adipogenic marker genes. The mRNA expressions level of C/EBPα, PPARγ, C/EBPβ, and fatty acid synthase (FAS) were dose-dependently inhibited by KGP treatment in 3T3-L1 mature adipocytes.Conclusions : In conclusion, these findings suggest that the KGP could be used in treatment of obesity and overweight related diseases.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.377-382
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• 2001

Mechanical behavior and electrical resistance change of CPDP (carbon particle dispersed plastic) composite consisting of epoxy resin and conductive carbon particle were investigated under monotonic loading and repeated loading-unloading. The electrical resistance almost linearly increased with increasing strain during loading and the residual electrical resistance was observed even after removing load. The value of the residual electrical resistance was dependent on the maximum strain under the applied stress. This result suggests that the estimation of maximum strain (i.e., damage) is possible by the measuring electrical resistance of composite. The behavior of electrical resistance change during and after loading was discussed on the basis of the results of microscopic deformation and fracture observation. Moreover, the relationship between the volume fraction of carbon particle and the electrical resistivity of CPDP was investigated in relation to the percolation theory. Simulation model of percolation structure was established by Monte Carlo method and the simulation result was compared to the experimental results. The electrical resistance change under applied loading was analyzed quantitatively using the percolation equation and a simple model for the critical volume fraction of carbon particle as a function of the mechanical stress. It was revealed that the prediction was in good agreement with the experimental result except in the region near the failure of material.

• Conservation Science in Museum
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• v.12
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• pp.35-45
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• 2011

To keep relics excavated in the era of the Japanese Colonist's rule in the Korean Peninsula in order, the National Museum of Korea selected some of horse strap pendants (Haengyeob) that were excavated from Seobongchong, Sikrichong and Geumryeongchong, and it investigated conservation and production technique. The horse strap pendants selected were classified into three, that is to say, Oval and fish-tail shape, heart shape and atypical: At the results of microscopic observation, XRF and SEM-EDS analysis, base plate was made of iron, and top plate as well as pattern plate was made of iron, copper and silver. Both Oval and fish-tail shape and heart shape horse strap pendants had horse strap pendants having same production technique and sizes at all of three ancient tombs were made of iron and copper. The gold layer of horse strap pendants except the atypical one having no gold layer were made by amalgam gilding.