• Nuclear Engineering and Technology
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• 제30권2호
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• pp.148-163
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• 1998

Flow Induced Material Degradation (FIMD) is reviewed focusing on Flow Accelerated Corrosion (FAC) models. Several examples of FAC related incidents are described, which include nuclear and fossile power plants. Lastly, mitigation techniques such as inspection, material selection, water chemistry, temperature, and hydrodynamic factor are discussed.

• Bulletin of the Korean Chemical Society
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• 제26권5호
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• pp.781-785
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• 2005

A fast and reliable method for the selective separation and preconcentration of $Cu^{2+}$ ions using homogeneous liquid-liquid extraction was developed. A new $\alpha$-dioxime derivative (2H-1,4-benzothioazine-2,3(4H)dionedioxime, Dioxime I) was synthesized and investigated as a suitable selective complexing ligand for $Cu^{2+}$ ions. Zonyl FSA (FSA) was applied as a phase-separator agent under the slightly acidic pH conditions. Under the optimal experimental conditions ([FSA] = 3.2% w/v, [THF] = 19.5% v/v, [Dioxime I] = 1.9 ${\times}\;10^{-3}$ M, and pH = 4.7), 10 ${\mu}g\;of\;Cu^{2+}$ in 5.2 mL aqueous phase could be extracted quantitatively into 80 $\mu$L of the sedimented phase. The maximum concentration factor was 65-fold. The limit of detection of the proposed method was 0.005 ng $mL^{-1}$. The reproducibility of the proposed method, on the 10 replicate measurements, was 1.3%. The influence of the pH, type and volume of the water-miscible organic solvent, concentration of FSA, concentration of the complexing ligand and the effect of different diverse ions on the extraction and determination of $Cu^{2+}$ ions were investigated. The proposed method was applied to the extraction and determination of $Cu^{2+}$ ion in different synthetic and natural water samples.

• 한국환경과학회지
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• 제15권6호
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• pp.503-511
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• 2006

Airborne particles collected from a heavily industrialized site were analyzed by chemical speciation of seven trace metals: Pb, Cd, Cr, Cu, Ni, Zn, and As. The average concentrations were as follows: $Zn,\;502.0{\pm}230.7;\;Pb,\;176.5{\pm}310.9;\;Cu,\;111.9{\pm}82.7;\;As,\;38.0{\pm}31.0;\;Cr,\;21.5{\pm}24.4;\;Cd,\;20.8{\pm}17.4;\;and\;Ni,\;11.4{\pm}8.4\;ng/m^3$. The median enrichment factor (EF) values of Cd (7,280), As (1,030), Cu (215), Zn (214), and Pb (143), with respect to iron, were much larger than 100. We observed that Cd was found in the soluble and exchange- able form (56.9%), and that Pb and Cr were found in carbonates, oxides and the reducible form (69.8% and 61.1%, respectively). These two forms, which are the most easily absorbed into human body tissue, predominated in most of the trace metals investigated in this study.

• Journal of Applied Biological Chemistry
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• 제51권1호
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• pp.7-12
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• 2008

The suitability of CPWs, by-products of the juice industry, was investigated as a source for the production of cosmeceuticals. Four kinds of CPWs, CW, CWE, CWER, and CWEA, were examined for their antioxidant potentials in terms of DPPH radical-scavenging ability for anti-wrinkle applications, inhibition of tyrosinase or melanin production for whitening products, and anti-inflammatory effects to treat various skin diseases such as atopic dermatitis and acne as well as for anti-bacterial activity against acne-inducing pathogens. Of the four extracts, CWER was the most potent tyrosinase inhibitor ($IC_{50}$ value: $109\;{\mu}g/mL$), and CWEA ($IC_{50}:\;167\;{\mu}g/mL$) showed good antioxidative effects. CWE and CWEA samples had dose-dependent inhibitory effects on the melanin production. The cytotoxic effects of the four CPWs were determined by colorimetric MTT assays using human keratinocyte HaCaT cells. Most extracts exhibited low cytotoxicity at $100\;{\mu}g/mL$. These results suggest CPWs are attractive candidates for topical applications on the human skin.

• Bulletin of the Korean Chemical Society
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• 제35권6호
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• pp.1737-1742
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• 2014

In this research, we further developed the one-step seed mediated method to synthesize gold nanoparticles (GNPs) and control their resulting shapes to obtain hexagonal, triangular, rod-shaped, and spherical gold nanostructures. Our method reveals that the reaction kinetics of formation of GNPs with different shapes can be controlled by the rate of addition of ascorbic acid, because this is the critical factor that dictates the energy barrier that needs to be overcome. This in turn affects the growth mechanism process, which involves the adsorption of growth species to gold nanoseeds. There were also observable trends in the dimensions of the GNPs according to different rates of addition of ascorbic acid. We performed further analyses to investigate and confirm the characteristics of the synthesized GNPs.

• Bulletin of the Korean Chemical Society
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• 제35권3호
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• pp.725-730
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• 2014

The effect the diameter of silver nanorod arrays whose distance between the nanorods was uniform at 65 nm have on Surface-enhanced Raman Scattering (SERS) has been studied by varying the diameter from 28 to 51 nm. Nanorod length was fixed at approximately 62 nm, which is the optimum length for SERS by excitation with a 632.8 nm laser line. The transverse and longitudinal modes of the surface plasmon of these silver nanorods were near 400 and 630 nm, respectively. The extinction of the longitudinal mode increased with increasing nanorod diameter, while the transverse mode did not change significantly. High-quality SERS spectra of p-aminothiophenol and benzenethiol adsorbed on the tips of the silver nanorods were observed by excitation with a 632.8 nm laser line. The SERS enhancement increased with increasing nanorod diameter. We concluded that the SERS enhancement increases when the diameter of silver nanorods is increased mainly by increasing the excitation efficiency of the longitudinal mode. The enhancement factor for the silver nanorods with a 51 nm diameter was approximately $2{\times}10^7$.

• Bulletin of the Korean Chemical Society
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• 제28권3호
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• pp.373-378
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• 2007

A micro organism Agrobacterium tumifacient as an immobilized cell on a solid support was presented as a new biosorbent in a simple and sensitive spectrophotometry determination of Ni(II) in various samples using 4-hydroxy benzaldehyde-4-bromophenyl hydrazone as a color developing agent (λmax 497 nm) at pH 4.0 ± 0.2. Beer's law was obeyed over the range of 0.01-0.1 μg L-1. The molar absorptivity and Sandell's sensitivity were 1.285 × 105 L mol-1cm-1 and 0.007245 μg cm-2 respectively. Under these conditions, the preconcentration factor obtained was 82, and the detection limit achieved was 0.05 μg L-1. The detailed study of various interfering ions made the method more sensitive and selective. The recovery of Ni(II) from various samples range from 97.75 to 99.35%. The present method was successfully applied for the determination of Ni(II) in spiked, natural water and alloy samples. The proposed method was compared with reported methods in terms of Student's ‘t'-test and Variance ratio ‘f'-test which indicates that there is no significant difference between proposed and literature method at 95% confidence level.

• Journal of Applied Biological Chemistry
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• 제44권2호
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• pp.84-86
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• 2001

Capsaicin synthesis by suspension cultured cells of Jalapeno pepper (Capcicum annuum L.) was assessed in vitro under various conditions including temperature (23 and $30^{\circ}C$), light intensity (with light and without light), and shaking speed (110 and 200 rpm). Capsaicin production increased, while the cell biomass growth decreased possibly due to the production of a secondary metabolite. Capsaicin synthesis was primarily affected by light condition. Cells cultivated at 110 rpm and $23^{\circ}C$ under light condition yielded the highest fresh weight, while those cultivated under the same condition, but without light resulted in the lowest cell mass. Capsaicin content in cells of 18-day-old pepper grown at 110 rpm and $23^{\circ}C$ under light was 0.125% of the cell mass. However, without light treatment, the capsaicin content in cells at the same shaking speed and temperature increased up to 169%, indicating no light is favored in the capsaicin synthesis by Jalapeno pepper. Increasing the shaking speed from 110 to 200 rpm without light enhanced the capsaicin synthesis. Results of this study demonstrate that light condition is the limiting factor in the synthesis of capsaicin in tissue-cultured Jalapeno pepper cells.

• Molecules and Cells
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• 제25권3호
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• pp.438-445
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• 2008

Leaf senescence is a highly regulated genetic process that constitutes the last stage of plant development and provides adaptive fitness by relocating metabolites from senescing leaves to reproducing seeds. Characterization of various senescence mutants, mostly in Arabidopsis, and genome-wide analyses of gene expression, have identified a wide array of regulatory components, including transcription factors and enzymes as well as signaling molecules mediating growth hormones and environmental stress responses. In this work we demonstrate that a membrane-associated NAC transcription factor, NTL9, mediates osmotic stress signaling in leaf senescence. The NTL9 gene is induced by osmotic stress. Furthermore, activation of the dormant, membrane-associated NTL9 is elevated under the same conditions. A series of senescence-associated genes (SAGs) were upregulated in transgenic plants overexpressing an activated form of NTL9, and some of them were slightly but reproducibly downregulated in a T-DNA insertional NTL9 knockout mutant. These observations indicate that NTL9 mediates osmotic stress responses that affect leaf senescence, providing a genetic link between intrinsic genetic programs and external signals in the control of leaf senescence.

• Fisheries and Aquatic Sciences
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• 제15권1호
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• pp.69-72
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• 2012

Effects of dietary nutrient content on the biological index and serum chemistry of olive flounder Paralichthys olivaceus achieving compensatory growth were investigated. Six treatments were prepared in triplicate. Fish were hand-fed with the control (C) diet twice daily for 8 weeks (8W-C) or fish were starved for 2 weeks and then hand-fed with the C, high protein (HP), high carbohydrate (HC), high lipid (HL), or intermediate protein, carbohydrate and lipid (IPCL) diets for 6 weeks, referred to as 6W-C, 6W-HP, 6W-HC, 6W-HL, and 6W-IPCL, respectively. Weight gain of fish in the 8W-C, 6W-HP, and 6W-IPCL treatments was higher than that of fish in the 6W-C treatment. Condition factor (CF) of the fish in the 6W-HP, 6W-HC and 6W-IPCL treatments was higher than that of fish in the 8W-C and 6W-C treatments. The hepatosomatic index (HSI) of fish in the 6W-HC, 6W-HL and 6W-IPCL treatments was higher than that of the fish in the 8W-C, 6W-C and 6W-HP treatments. Serum chemistry except triiodothyronine ($T_3$) was not significantly different among the treatments. In conclusion, CF and HSI of the fish could be indices reflecting compensatory growth, whereas $T_3$ seemed to play a partial role in achieving compensatory growth.