• Journal of dental hygiene science
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• v.15 no.4
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• pp.419-423
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• 2015

Recently, energy drink consumption is rising. The purpose of this study was to examine the effect of energy drink on enamel erosion by measuring pH and titratable acidity in energy drink on the market. pH and titrable acidity in drink were measured by selecting 3 kinds of energy drinks with high sales volume among energy drinks on the domestic market. To evaluate the erosion level of normal enamel, the erosion level was measured by using a surface micro-hardness after soaking it in drink for 1 minute, for 3 minutes, for 5 minutes, for 10 minutes, and for 30 minutes while using 10 pieces of bovine specimens per each group. All the energy drinks were containing citric acid. As for pH in drinks, pH of Burn intense was the lowest with $2.51{\pm}0.01$. Hotsix stood at $3.16{\pm}0.01$. Redbull stood at $3.37{\pm}0.00$. In pH 5.5, the titrable acidity of Burn intense was 3.59 ml. Redbull was 3.43 ml. Hotsix was 1.92 ml. All the energy drinks were reduced the surface micro-hardness according to a rise in time of immersion. Following the 30-minute treatment in drinks, the surface micro-hardness value was indicated to be the lowest in Redbull with $119.72{\pm}15.16$ VHN. It was shown to be in order of Hotsix $208.75{\pm}10.99$ and Burn intense $210.47{\pm}8.01$. Hotsix and Burn intense had no statistically significant difference (p>0.05). Accordingly, all the energy drinks, which were used in the experiment, caused the tooth enamel erosion. Among them, Redbull led to the largest enamel erosion. Thus, energy drink containing citric acid and low pH can cause the enamel erosion. However, it is thought to be necessarily progressed by considering factors of influencing etching a little more diversely by additionally analyzing intraoral factors, acid kinds, and even the content in calcium, phosphate and fluoride.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.sup3
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• pp.179-183
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• 2016

Breast cancer is the most prevalent type of cancer among women around the world, and mortality is primarily caused by micro-metastatic disease. The complex mechanisms of breast cancer invasion and metastasis are intrinsically related to the malignant cell type so that early detection of micro-metastases can help prolongation of survival for patient. The aim of the present research work was evaluation of the expression status of mammoglobin protein as a candidate molecular marker in the negative sentinel lymph node (SLN). Fifty tumor specimens, and 50 normal adjacent breast tissue samples from the same patients were selected on the basis of having more than 10% tumor content for RNA extraction from SLNs. Tumor samples and normal adjacent breast tissue were archived in the form of frozen fresh tissue in liquid nitrogen. Real-time PCR was performed on a Bioner life express gradient thermal cycler system. Mammoglobin gene overexpression in breast cancer metastasis was investigated. Single marker results were mammaglobin 66.7% and CK19 50.0%, with 58.3% for the two in combination. Due to improved outcome with at least 3 genes (83.3%), it seems, triple marker evaluation will be most likely useful for detecting micro-metastases instead of studying separate genes.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.5
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• pp.1901-1906
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• 2012

Background: The discovery that microRNA (miRNA) regulates metastasis provide a principal molecular basis for tumor heterogeneity. A characteristic of solid tumors is their heterogenous distribution of blood vessels, with significant hypoxia occurring in regions (centers of tumor) of low blood flow. It is necessary to discover the mechanism of breast cancer metastasis in relation to the fact that there is a differential distribution of crucial microRNA in tumors from centers to edges. Methods: Breast tissues from 48 patients (32 patients with breast cancer) were classified into the high invasive and metastatic group (HIMG), low invasive and metastatic group (LIMG), and normal group. Samples were collected from both the centers and edges of all tumors. The first six specimens were detected by microRNA array, and the second ten specimens were detected by real-time qRT-PCR and Western blot analyses. Correlation analysis was performed between the miRNAs and target proteins. Results: The relative content of miR-20a and miR-20b was lower in the center of the tumor than at the edge in the LIMG, lower at the edge of the tumor than in the center in the HIMG, and lower in breast cancer tissues than in normal tissues. VEGF-A and HIF-1alpha mRNA levels were higher in the HIMG than in the LIMG, and levels were higher in both groups than in the normal group; there was no difference in mRNA levels between the edge and center of the tumor. VEGF-A and HIF-1alpha protein levels were higher in the HIMG than in the LIMG, and protein levels in both groups were higher than in the normal group; there was a significant difference in protein expression between the edge and center of the tumor. Correlation analysis showed that the key miRNAs (miR-20a and miR-20b) negatively correlated with the target proteins (VEGF-A and HIF-1alpha). Conclusions: Our data suggest that miR-20a and miR-20b are differentially distributed in breast cancer, while VEGF-A and HIF-1alpha mRNA had coincident distributions, and VEGF-A and HIF-1alpha proteins had uneven and opposing distributions to the miRNAs. It appears that one of the most important facets underlying metastatic heterogeneity is the differential distribution of miR-20a and miR-20b and their regulation of target proteins.

• Journal of Bio-Environment Control
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• v.13 no.3
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• pp.135-142
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• 2004

The objective of this study was carried out to determine which method is effective for improving seed germination in carrot and onion among osmotic or solid matrix priming. Seeds were osmotic primed with -0.5 MPa polyethylene glycol 8000 (PEG) solution and solid matrix primed with Micro Cel E (seed, Micro Cel E, and water mixed with the ratio of 4.0：2.0：8.0 by weight for carrot, and the ratio of 4.0：1.2：5.0 for onion at $20^{\circ}C$ for 4 days). Seeds were rapidly absorbed water after osmotic priming and solid matrix priming treatment. The moisture content of solid matrix primed seeds was lower than that of osmotic primed seeds in carrot and onion. Osmotic priming and solid matrix priming did not influenced on increasing of percent germination, but $T_{50}$ of treated seeds was shorter than those of untreated seeds at four temperature regimes. The effects of osmotic or solid matrix priming in reducing the $T_{50}$ was greater when the seeds were germinated at $15^{\circ}C$ than at $25^{\circ}C$ and $30^{\circ}C$ temperature. Solid matrix primed seeds germinated faster than osmotic primed seeds at all temperature in both carrot and onion. After priming, surface-dried seeds germinated faster than dried-back seeds in carrot and onion. Emergence speed of carrot and onion seeds was faster than untreated seeds by osmotic priming or SMP treatment although the final emergence percentage was not significantly influenced. On the other hand, early growth was not significantly influenced by osmotic priming or SMP treatment of carrot and onion seeds.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.2
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• pp.65-69
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• 2014

Crystallographic phases of Plasma electrolytic oxidized Al alloy, A1100, A5052, A6061, A6063, A7075, were investigated. Two types of electrolyte $Na_2Si_2O_3$ and Na2P2O7 were also compared. Bipolar pulse, $2000{\mu}sec$ with $400{\mu}sec+420V$ impulse and $300{\mu}sec$ - impulse were applied for 20 min. ${\alpha}-alumina$, ${\gamma}-alumina$, ${\eta}-alumina$, $Al_{4.95}Si_{1.05}O_{9.52}$, and $(Al_{0.9}Cr_{0.1})_2O_3$ were mainly observed. Si, component of electrolyte, were moved into the PEO layer by bipolar pulse. Glassy phase was also observed at the surface of $Na_2Si_2O_3$ electrolyte treated PEO layer, and increased with the Mg content of Al alloy. It is concluded that at first glassy phase was formed by the micro plasma, and the high temperature of plasma turns glassy phase to several crystalline phases. And we could expect that many other crystalline phase could be formed by PEO process.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.4
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• pp.57-64
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• 2022

Chloride, which is one of the main deterioration factors in reinforced concrete structures, can degrade the performance of the structure due to chloride-induced corrosion of steel. Chloride content at steel depth or the rate of chloride penetration is necessary to determine deterioration of reinforced concrete or to calculate initiation time of steel corrosion caused by chloride attack. Chlorides in concrete are generally identified with typical two methods including chloride profiling using potentiometric titration method and discoloration method using AgNO₃ solution. The former is advantageous to estimate chloride penetration rate (diffusion coefficient in general) with measured chloride contents directly, but it is laborious. In the case of latter, while the result is obtained easily with the range of discoloration, the error may occur depending on workmanship when the depth of chloride ingress is measured. This study shows that chloride penetrated depth is evaluated with the results obtained from discoloration method through image analysis, thereby the error is minimized by workmanship. In addition, the effect of micro-crack in concrete is studied on chloride penetration. In conclusion, the depth of chloride penetration was quantified with image analysis and as it was confirmed that chlorides can rapidly penetrate through micro-cracks, caution is especially required for cracks in concrete structure.

• Corrosion Science and Technology
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• v.6 no.4
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• pp.147-153
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• 2007

This study sought to investigate the reaction of Co-binder containing tungsten with molten zinc. Four kinds of Co-W alloys (pure, 10%W, 20%W, 30%W) were prepared using the powder metallurgy method. The specimens were immersion-tested in molten pure zinc baths at $460^{\circ}C$. To evaluate the corrosion property in molten zinc, the weight loss of the specimen was measured after the immersion tests at different immersion times (10~300 min.). Co-10%W alloys, compared with pure cobalt, showed no effect of tungsten addition on the reaction rate in molten zinc. The relationship between the weight loss and the square root of immersion period represents a straight line in both pure cobalt and Co-10%W alloy. The Co-Zn reaction layer in Co- 1O%W alloy consists of $\gamma2$, $\gamma1$, $\gamma$ and ($\beta1$ phases. The rate of weight loss significantly increases and the weight loss behavior is not well accord with the linear relationship as the tungsten content in the Co-W alloy increases. The $\beta1$ layer was not formed on the Co-20%W alloy and neither was a stable Co-Zn intermetallic compound layer found on the Co-30%W alloy. The main cause of increase in reaction rate with increasing tungsten content is related with the instability of the Co-Zn reaction phases as seen on micro-structural analysis.

• Journal of Korea Foundry Society
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• v.24 no.1
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• pp.40-44
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• 2004

The influence of Pd and Ag additions on the thermal stability, the glass forming ability (GFA) and mechanical property of $Zr_{55}Al_{10}Cu_{20}Ni_{10}Pb_{(5-x)}Ag_x$ (x = $0{\sim}5at%$) alloys obtained by melt spun and injection casting method have been investigated by using of X-ray diffraction, thermal analysis (DTA, DSC) and micro-Vickers hardness(Hv) testing. The thermal properties of melt-spun $Zr_{55}Al_{10}Cu_{20}Ni_{10}Pb_{(5-x)}Ag_x$ (x = $0{\sim}5at%$) alloys exhibit a supercooled liquid region(${\Delta}T_x$) exceeding 91 K before crystallization. The largest ${\Delta}T_x$ reaches as large as 126 K for the $Zr_{55}Al_{10}Cu_{20}Ni_{10}Pb_5$ alloy. The reduced glass transition temperature, $T_{rg}$ increased with increasing Ag content. The largest $T_{rg}$ is obtained for the $Zr_{55}Al_{10}Cu_{10}Ni_{10}Ag_5$ alloy. The $Zr_{55}Al_{10}Cu_{10}Ni_{10}Ag_5$ bulk amorphous alloy rod with 3 mm in diameter was fabricated by injection casting. Hv increased with increasing Ag content and the largest value was obtained for the $Zr_{55}Al_{10}Cu_{10}Ni_{10}Ag_5$ bulk amorphous alloy.

• Korean Journal of Materials Research
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• v.22 no.4
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• pp.169-173
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• 2012

Recently, various attempts to produce a heat sink made of Al 6xxx alloys have been carried out using die-casting. In order to apply die-casting, the Al alloys should be verified for die-soldering ability with die steel. It is generally well known that both Fe and Mn contents have effects on decreasing die soldering, especially with aluminum alloys containing substantial amounts of Si. However, die soldering has not been widely studied for the low Si aluminum (1.0~2.0wt%) alloys. Therefore, in this study, an investigation was performed to consider how the soldering phenomena were affected by Fe and Mn contents in low Si aluminum alloys. Each aluminum alloy was melted and held at $680^{\circ}C$. Then, STD61 substrate was dipped for 2 hr in the melt. The specimens, which were air cooled, were observed using a scanning electron microscope and were line analyzed by an electron probe micro analyzer. The SEM results of the dipping soldering test showed an Al-Fe inter-metallic layer in the microstructure. With increasing Fe content up to 0.35%, the Al-Fe inter-metallic layer became thicker. In Al-1.0%Si alloy, the additional content of Mn also increased the thickness of the inter-metallic layer compared to that in the alloy without Mn. In addition, EPMA analysis showed that Al-Fe inter-metallic compounds such as $Al_2Fe$, $Al_3Fe$, and $Al_5Fe_2$ formed in the die soldering layers.

• Journal of the Korean Ceramic Society
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• v.52 no.4
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• pp.294-298
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• 2015

Blocking layers with nano carbon blacks (NCBs) were prepared by adding 0.0 ~ 0.5 wt% NCBs to the $TiO_2$ blocking layer. Then, dye sensitized solar cells (DSSCs) were fabricated with a $0.45cm^2$ active area. TEM and micro-Raman spectroscopy were used to characterize the microstructure and phases of the NCBs, respectively. Optical microscopy and AFM were used to analyze the microstructure of the $TiO_2$ blocking layer with NCBs. UV-VIS-NIS spectroscopy was used to determine the band gap of the $TiO_2$ blocking layer with NCBs. A solar simulator and potentiostat were used to determine the photovoltaic properties and impedance of DSSCs with NCBs. The energy conversion efficiency (ECE) increased from 3.53 to 6.20 % when the NCB content increased from 0.0 to 0.3 wt%. This indicates that the effective surface area and electron mobility increased in the $TiO_2$ blocking layer with NCBs. However, the ECE decreased when the NCB content was increased to over 0.4 wt%. This change occurred because the effective electron transport area decreased with the addition of excessive NCBs to the $TiO_2$ blocking layer. The results of this study suggest that the ECE of DSSCs can be enhanced by adding the appropriate amount of NCBs to the $TiO_2$ blocking layer.