• Elastomers and Composites
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• v.54 no.4
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• pp.313-320
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• 2019

A typical wear pattern was reported to resemble the fatigue crack growth behavior considering its mechanism, especially for amorphous rubbers such as styrene-butadiene rubber (SBR). In this study, the wear and crack growth rates were correlated using two separate experiments for carbon black and silica-reinforced selected rubber compounds. The wear rate was determined using a blade-type abrasion tester, where the frictional energy input during wearing was measured. The crack propagation rate was determined under different tearing energy inputs using a home-made fatigue tester, with a pure-shear test specimen containing pre-cracks. The rates of abrasion and crack propagation were plotted on a log-log scale as a function of frictional and tearing energies, respectively. Reasonable agreement was observed, indicating that the major mechanism of the abrasion pattern involved repeated crack propagation.

• Archives of Pharmacal Research
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• v.16 no.4
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• pp.276-282
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• 1993

This study has been undertaken to examine the effect of 3-methylcholanthrene (3MC) on rat uterine growth and to understand the mechanism of action of 3MC in rat uterus. After diethylstilbesterol(DES) or tamoxifen(TAM) or 3MC or DES plus TAM or DES plus 3MC was administered into immature female rats, uterine weight over corn oil-treated uteri. 3MC treatment had no effect on uterine weight but, DES stimulated uterine weight was inhibited by 3MC concomitant tratment. While TAM alone treatment showed slight increase in uterine wieght, inhibited uterine growth simulated by DES when it was adiministrated with DES condirect binding assay with $[^3H]$ estradiol and the relative binding affinities of 3MC and TAM were estimated by competetion assy. Estradiol tumed out to have high affinity for rat uterine estrogen receptor (kd = 0.4 nM). The relative binding affinities of TAM and 3MC were 1% and 4.7% that of DES for rat uterine estrogen receptor, respectively. 3MC was shown to have similar affinity for eat uterine estrogen receptor to that of TAM. Effects of DES 3MC and TAM administration in vivo on rat uterine estrogen recptor level were examined. It was confirmed that the estrogen, DES and antiestrogen, TAM decreased estrogen receptor levels from rat ulterus and also 3MC decreased rat uterine estrogen receptor level when rats were treated with DES, TAM and 3MC in vivo. Data indicates that 3MC acts as an antiestrogen mediated through estrogen receptor system.

• Journal of Microbiology and Biotechnology
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• v.16 no.4
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• pp.531-537
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• 2006

Lactic acid-producing bacteria (LABs) are known to have various beneficial properties for health. However, they are generally considered to have an adverse effect on teeth, since they produce acid. Nonetheless, milk and cheese containing specific LAB strains were recently found to have an inhibitory effect on dental caries in children, with an inhibitory activity towards the growth of Streptococcus mutans suggested as the responsible mechanism. Accordingly, the current study selected a probiotic candidate for oral health and studied its inhibitory mechanism against dental caries. Twenty-two LAB species belonging to eleven genuses were screened for promoting bone nodule formation using direct microscopic examination. Only one isolate, Weissella kimchii strain PL9001, increased the bone nodule formation significantly. The addition of W. kimchii strain PL9001 to bone cells prepared from mouse calvaria increased the bone nodule formation, calcium accumulation, and activity of alkaline phosphatase (the osteoblastic marker). Moreover, W. kimchii strain PL9001 inhibited the invasion of Streptococcus mutans into bone cells, and an organic extract of the culture supernatant of W. kimchii strain PL9001 inhibited the growth of Strep. mutans. Therefore, the results suggest that W. kimchii strain PL9001 can be used as a preventive measure against dental caries. This is the first time that a LAB has been shown to promote bone nodule formation and prevent the invasion of Strep. mutans into bone cells.

• Molecules and Cells
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• v.28 no.5
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• pp.495-499
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• 2009

Although insulin-like growth factor-I (IGF-I) and androgen receptor (AR) are well known effectors of skeletal muscle, the molecular mechanism by which signaling pathways integrating AR and IGF-I in skeletal muscle cells has not been previously examined. In this study, the role of PI3K/Akt on IGF-I-induced gene expression and activation of AR in skeletal muscle cells was investigated. C2C12 cells were treated with IGF-I in the absence or presence of inhibitors of PI3K/Akt pathway (LY294002 and Wortmannin). Inhibition of the PI3K/Akt pathway with LY294002 or Wortmannin led to a significant decrease in IGF-I-induced AR phosphorylation and total AR protein expression. Furthermore, IGF-I-induced AR mRNA and skeletal ${\alpha}-actin$ mRNA were blocked by LY294002 or Wortmannin. Confocal images showed that IGF-I-induced AR translocation from cytosol to nucleus was inhibited significantly in response to treatment with LY294002 or Wortmannin. The present results suggest that modulating effect of IGF-I on AR gene expression and activation in C2C12 mouse skeletal muscle cells is mediated at least in part by the PI3K/Akt pathway.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.48 no.2
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• pp.125-129
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• 2022

Sialolithiasis is a condition in which the salivary gland excretory duct is obstructed due to the formation of calcareous deposits and is uncommon in children compared to adults. The treatment modalities range from a conservative approach involving hydration to a surgical approach. Though several studies have analyzed the sialolith micromorphology structures, studies on pediatric sialoliths remain scarce. This brief communication aims to describe the sialolith micromorphology to understand the mechanism of mineralization and growth of pediatric sialoliths. A 6-year-old Korean female presented with swelling under her tongue. The intraoral examination revealed a painless yellowish hard mass beneath the tongue near the Wharton's duct which was suspected as a sialolith. After receiving the informed consent, the sialolithotomy was performed under local anesthesia. The obtained stone was analyzed through histopathology and transmission electron microscope examinations to understand the mechanism of mineralization and growth of pediatric sialolith. The micromorphology and growth processes of pediatric sialolith remain undescribed. More comprehensive microscopic studies are needed regarding their distinctive characteristics. By expanding knowledge about sialoliths micromorphology, development of new preventive, diagnostic and patient-tailored treatment methods of pediatric sialolithiasis will be enhanced.

• Carbon letters
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• v.6 no.2
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• pp.101-105
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• 2005

Like bamboo-sprouts after rains, numerous sub${\mu}m$-sized pyrocarbon whiskers growth on the Mullite ($3Al_2O_3{\cdot}2H_2O$) substrate could be observed through a looking glass during methane pyrolysis at the temperature of $1050^{\circ}C$ in this study. If the surface of substrate would be scrubbed strongly with iron metals, then finely sticked iron particles were more effective catalytic for nm-sized whisker growth. Numerous fine flakes of pyrolytic carbon were hanging by invisible nm-whiskers as like as small spiders hanging by a spiderweb. This is the identification of nm-sized whisker growth. Therefore if the pyrolysis would be stopped at the initial stage of the whisker growth, the primary lengthening growth was nm-sized whisker. So could we vary arbitrarily sizes of whisker from nm- to ${\mu}m$-sizes. But ${\mu}m$- and nm-whiskers grown with the different growth mechanism; the former was straight and the latter has twigs, The lengthening growth of whisker was depended on the flow pattern pyrolysis species on the active sites of substrate and on the growth duration. We could obtained straight whisker length of 10~20 ${\mu}m$/min during the primary growth and laboratory spiral whisker of 30~40 ${\mu}m$-diameter/hr during the secondary growth.

• Proceedings of the Korean Society of Toxicology Conference
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• 2003.05a
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• pp.66-67
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• 2003

It is well known that osteoblasts and osteoc1asts playa key role in bone metabolism. They involve in osteoformation or bone destruction which are ragulated by various factors such as thyroid hormone, parathyroid hormone, estrogen, growth factor and cytokine. Recently, it is demonstrated that oxidative stress is one of pathological factors in bone metabolism, but it is left unknown about mechanism between oxidative stress and bone metabolism.(omitted)

• Journal of the Korean Ceramic Society
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• v.25 no.1
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• pp.78-82
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• 1988

Good quality LiNbO3 single crystals which can be applied to SAW devices, were grown by Czochralski method. It was observed that the gas-bubbles were concentrated in ring shape at the outer part of grown crystals, and this anomaly was illustrated by modeling the mechanism of gas-bubble entrapment according to the melt flow pattern in the crucible. And this mechanism was also encertained by observation of solid-liquid interface shape of grown crystals. The optimal condition for good quality crystals was known that the solid-liquid interface shape was slightly concave.

• YAKHAK HOEJI
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• v.31 no.3
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• pp.164-172
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• 1987

The anti-inflammatory mechanism of daidzein was investigated in rats and mice. Daidzein and 4'-methyldaidzein inhibited capillary permeability and lipid peroxidation. Daidzein inhibited growth of granuloma when it was administered into the carrageenin pouch at the low dose, while it acted contrarily at the high dose. Daidzein decreased the antiinflammatory effect in adrenalectomized rat, depleted ascorbic acid and cholesterol contents in adrenals, and increased corticosterone level in plasma, suggesting dadzein acts on the hypophysisadrenal system.

• Polymer(Korea)
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• v.28 no.1
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• pp.35-40
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• 2004

The formation mechanism of void defect which deteriorate composite's property is various according to each composite process. In this paper, void formation and growth mechanism is analyzed by thermal analysis and GC/MS. We made a vacuum chamber for observing pressure effect. Thermal analysis has been done in various condition. Elements of volatiles during resin curing were turned out by GC/MS. The most of volatiles of polyester were composed of styrene (over 80%) and a small quantity of toluene. In case epoxy resin, butyl glycidyl ether was the main element of volatiles (over 90%). We concluded that the original sites of void growth existed in resin and they were eliminated by vacuum and heating process. And the growth of void was influenced by water, diluents, solvent, and reactants in resin.