• Development and Reproduction
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• v.17 no.4
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• pp.421-426
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• 2013

In this study, oocyte steroidogenesis are investigated in relation to oocyte development in the starry flounder, Platichthys stellatus, a marine multiple spawner. Vitellogenic (0.52 and 0.55 mm oocyte diameter) and mature oocytes (0.63, 0.66 and 0.71 mm oocyte diameter) were incubated in vitro in the presence of $[^3H]17{\alpha}$-hydroxyprogesterone ($[^3H]17{\alpha}$-OHP) as a precursor. Steroid metabolites were extracted from the incubated media and oocytes, the extracts were separated and identified by thin-layer chromatography (TLC), high performance liquid chromatography (HPLC) and gas chromatographymass spectrometry (GC-MS). The major metabolites produced from $[^3H]17{\alpha}$-OHP were androgens [androstenedione ($A_4$) and testosterone (T)] and estrogens [$17{\beta}$-estradiol ($E_2$) and estrone ($E_1$)] and progestins [$17{\alpha},20{\alpha}$-dihydroxy-4-pregnen-3-one ($17{\alpha}20{\alpha}P$) and $17{\alpha},20{\beta}$-dihydroxy-4-pregnen-3-one ($17{\alpha}20{\beta}P$)] in vitellogenic and mature oocytes. The results from this study suggest the potential roles of $E_1$ in the oocytes with diameter 0.52-0.71 mm, $17{\alpha}20{\alpha}P$ and $17{\alpha}20{\beta}P$ at the oocytes of 0.63, 0.66 and 0.71 mm.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.6
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• pp.309-313
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• 2013

Silicon carbide (SiC) has recently drawn an enormous industrial interest because of its useful mechanical properties such as thermal resistance, abrasion resistance and thermal conductivity at high temperature. Especially, high purity SiC is applicable to the fields of power semiconductor and lighting emitting diode (LED). In this work, high purity carbon powders as raw material for high purity SiC were prepared by a RF induction thermal plasma. Dodecane ($C_{12}H_{26}$) as hydrocarbon liquid precursor has been utilized for synthesis of high purity carbon powders. It is found that the filtercollected carbon powders showed smaller particle size (10~20 nm) and low crystallinity compared to the reactor-collected carbon powders. The purities of reactor-collected and filter-collected carbon powders were 99.9997 % (5N7) and 99.9993 % (5N3), respectively. In addition, the impurities of carbon powders synthesized by RF induction thermal plasma were mainly originated from the surrounding environment.

• KSBB Journal
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• v.21 no.5
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• pp.366-370
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• 2006

In this research, analysis of UDP-glucose a precursor of ${\beta}$-1,3-glucan by high performance liquid chromatography(HPLC) was established using a reversed phase system. One of key metabolite UDP-glucose was selected and its concentration changes was measured with the change of fermentation conditions. The effects of fermentation conditions with/without nitrogen source for cell growth on ${\beta}$-1,3-glucan production were dependent on the UDP-glucose concentration. The UDP-glucose was synthesized rapidly during cell exponential growth period and maintained high during ${\beta}$-1,3-glucan production period. The UDP-glucose concentration was higher for ${\beta}$-1.3-glucan production fermentor than that for cell growth fermentor. The ${\beta}$-1,3-glucan production was optimal at pH 5.5 and synthesis of ${\beta}$-1,3-glucan was greatest at pH 5.5.

• Journal of Plant Biology
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• v.34 no.2
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• pp.101-106
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• 1991

Effects of two auxins, 2,4-dichlorophenoxyacetic acid (2,4-D) and a-napthaleneacetic acid (NAA) on nicotine production during callus culture of a wild tobacco (Nicotiana glauca) were investigated using a high performance liquid chromatography (HPLC). The high concentration ($11.5\;\mu\textrm{M}$)of 2,4-D and NAA had peaks of nicotine contents at 4th and 2nd week, respectively. Thereafter, the concents decreased and the nicotine was metabolized to other alkaloids. The low concentration ($1.5\;\mu\textrm{M}$) of 2,4-D on the medium supplemented with 0.1 mM of L-aspartic acid or L-arginine inhibited nicotine production. However, the low NAA promoted it only when the medium was supplemented with L-aspartic acid. From these results, it could be concluded that both auxins exhibit different action mechanisms on nicotine production pathway and the low NAA promotes the activities for the pathway with L-aspartic acid as a precursor.cursor.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.4
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• pp.483-488
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• 2015

We studied oocyte steroidogenesis in the blackfin flounder Glyptocephalus stelleri as a region-specific species, in the East Sea of Korea during the spawning season. Maturing oocytes (0.76, 0.82, 0.88, and 0.91 mm in oocyte diameter) were incubated in vitro in the presence of [$^3H$] $17{\alpha}$-hydroxyprogesterone ($[^3H]17{\alpha}$-OHP) as a precursor. Steroid metabolites were extracted from the incubated medium and oocytes, and the extracts were separated and identified by thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC) and gas chromatographymass spectrometry (GC/MS). The major metabolites produced from $[^3H]17{\alpha}$-OHP were androgens [androstenedione (A4) and testosterone (T)] and estrogens [$17{\beta}$-estradiol (E2) and estrone (E1)] and progestins [$17{\alpha},20{\alpha}$-dihydroxy-4-pregen-3-one ($17{\alpha}20{\alpha}P$) and $17{\alpha}20{\beta}$-dihydroxy-4-pregnen-3-one ($17{\alpha}20{\beta}P$)] in maturing oocytes. The metabolic rate of $17{\alpha}20{\beta}$ was elevated (29.04%) in oocytes measuring 0.88 mm (nucleus migration stage following the induction of germinal vesicle breakdown), but was very low in oocytes measuring 0.76, 0.82, and 0.91 mm (0.42, 0.67, and 2.62%, respectively). From these results, we suggest that $17{\alpha}20{\beta}P$ acts as a maturation-inducing steroid in the blackfin flounder.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.4
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• pp.370-375
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• 2014

BACE2 is a membrane-bound aspartic protease that is highly homologous with BACE1. While BACE1 processes the amyloid precursor protein (APP) at a key step in generating ${\beta}$-amyloid peptide and presumably causes Alzheimer's disease (AD), BACE2 has not been demonstrated to be involved in APP processing directly, and its physiological functions are unknown. To determine its function and to develop inhibitors from marine sources, we constructed an overexpression vector for producing BACE2. The gene encoding human BACE2 protease was amplified using the polymerase chain reaction and cloned into the pET11a expression vector, resulting in pET11a/BACE2. Recombinant BACE2 protease was overexpressed successfully in E. coli as inclusion bodies, refolded using the rapid-dilution method, and purified via two-step fast protein liquid chromatography using Sephacryl S-300 gel filtration and Resource-Q column chromatography. The BACE2 protease produced was an active form. This study provides an efficient method not only for studying the basic properties of BACE2, but also for developing inhibitors from natural marine sources.

• Nutrition Research and Practice
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• v.4 no.1
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• pp.23-29
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• 2010

Poly-gamma-glutamic acid ($\gamma$-PGA) is a mucilaginous and biodegradable compound produced by Bacillus subtilis from fermented soybeans, and is found in the traditional Korean soy product, cheongkukjang. This study was carried out to evaluate the effects of $\gamma$-PGA from a food source on the concentration of the neurotransmitter GABA and its metabolic precursor glutamate in diet-induced obese rats. Eight-week old male Sprague-Dawley rats (n=60) were used. The rats were divided into two groups and obesity was induced by providing either a 10% control fat or 45% high fat diet for 5 weeks. The rats were then blocked into 6 groups and supplemented with a 0.1% $\gamma$-PGA diet for 4 weeks. After sacrifice, brain and serum GABA and glutamate concentrations were analyzed by high performance liquid chromatography with fluorometric detection. The rats fed the high fat diet had significantly increased body weights. $\gamma$-PGA supplementation significantly increased serum concentrations of glutamate and GABA in the control fat diet groups while this effect was not found in the high fat groups. In the brain, glutamate concentrations were significantly higher in the $\gamma$-PGA supplemented groups both in rats fed the normal and high fat diets than in the no $\gamma$-PGA controls. GABA concentrations showed the same tendency. The results indicated that $\gamma$-PGA intake increased GABA concentrations in the serum and brain. However, the effects were not shown in obese rats.

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.5
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• pp.639-650
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• 2018

Identification of the major sources contributing to PM is of importance in order to understand their quantitative contributions to atmosphere. In the viewpoint of the meat cooking in Korea, only a few analyses of organic molecular markers have been conducted due to analytical difficulties. In this study, ten different parts of meat (i.e., blade shoulder, belly, and arm shoulder of pork; ribeye roll, top blade muscle, and short plate of beef; leg quarter, breast, and wing of chicken; duck; mackerel) were pyrolyzed to generate the cooked PM using an electronic heating plate. Generated PM were collected by the pyrolysis sampling system to identify total carbon (TC) using a carbon analyzer and cholesterol using a Liquid chromatography tandem-mass spectrometry (LC-MSMS) based on fragmentor voltage (FV), precursor ion, collision energy, product ion. In addition, oxydative potential (OP) analysis using dithiothreitol (DTT) method were discussed to investigate the toxicity relates. Highly correlated pairwise scatterplots between the cholesterol and TC indicate that oxydative potential was highly associated with different parts of meat. This study provides insight into the meat cooking components of PM, which could be drivers of the oxidative potential relates.

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.5
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• pp.651-658
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• 2018

Particulate matter (PM) emitted from fossil fuel-combustion facilities can be classified as either filterable or condensable PM. The U.S. Environmental Protection Agency (EPA) defined condensable PM as material that is in the phase of vapor at the stack temperature of the sampling location which condenses, reacts upon cooling and dilution in the ambient air to form solid or liquid in a few second after the discharge from the stack. Condensable PM passed through the filter media and it is typically ignored. But condensable PM was defined as a component of primary PM. This study investigates the change of condensable PM according to the variation in the sulfur dioxide of combustion gas. Domestic oil boilers were used as the source of emission ($SO_2$) and the level of $SO_2$ concentration (0, 50, 80, and 120 ppm) was adjusted by diluting general light oil and marine gas oil (MGO) that contains sulfur less than 0.5%. Condensable PM was measured as 2.72, 6.10, 8.38, and $13.34mg/m^3$ when $SO_2$ concentration in combustion gas were 0, 50, 80, and 120 ppm respectively. The condensable PM tended to increase as the concentration of $SO_2$ increased. Some of the gaseous air pollutants emitted from the stack should be considered precursors of condensable PM. The gas phase pollutants which converted into condensable PM should reduced for condensable PM control.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.388-391
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• 1999

Well oriented Bi2212 superconductor thick films were formed successfully on a copper substrate by liquid reaction between a Cu-free precursor and Cu tape method in which Cu-free BSCO powder mixture was' printed on copper plate and heat-treated. And we examined the effect of heat-treatment atmosphere for the superconducting properties and microstructure of Bi2212. The composition of Cu-free BSCO powder mixture was Bi$_2O_3$ : SrCO$_3$ : CaCO$_3$ = 1.2~2 : 1 : 1 and the heat-treatment for the superconducting formation reaction was performed in air, oxygen, nitrogen and low oxygen pressure. At heat-treatment temperature, the printing layer partially melt by reacting with CuO of the oxidizing copper plate, and the nonsuperconducting phases present in the melt are typically Bi-free phases and Cu-free phases. Among the nonsuperconducting phases, it is known that the (Sr,Ca)CuO$_3$ phase restrain the formation of the Bi2212 superconducting phase. Because a kind of the nonsuperconducting phases is controled by the oxygen partial pressure, the optimum condition in which the remnants of the second phases don't leave in the fully processed conductor was determined by XRD and the critical tempera to re (Tc) analysis.