• Korean Journal Plant Pathology
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• v.13 no.1
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• pp.1-4
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• 1997

Viroid-like RNA molecules were detected from the low molecular weight RNAs isolated from the Korean peonies which showed typical viroid symptoms of epinasty and dwarfing. Low molecular weight RNAs including viroid RNA molecules were purified by the Qiagen anion exchange minicolumns. Viroid-like RNA molecules showed a single viroid specific band in the native polyacrylamide gel. They were separated into two bands in the denaturing gel conditions. The band of circular form of viroid-like RNAs was crossed over the horizontal band of the linear form of viroid-like RNA molecules in 0~8 M urea gradient gel under the denaturing conditions of 37$^{\circ}C$. The two circular forms of viroid-like RNA molecules were detected in the reverse polyacrylamide gel electrophoresis. The viroid-like RNA molecules purified from the peonies were supposed to be unidentified viroid RNA molecules.

• Journal of the Korean Wood Science and Technology
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• v.47 no.2
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• pp.221-228
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• 2019

This study reports the performance of urea-formaldehyde (UF) resins prepared at two different low formaldehyde/urea (F/U) mole ratios with different numbers of urea addition during synthesis. The second or third urea was added during the synthesis of UF resins to obtain two different low molar ratios of 0.7 and 1.0, respectively. The molecular weights, cure kinetics, and adhesion performance of these resins were characterized by the gel permeation chromatography, differential scanning calorimetry, and tensile shear strength of plywood, respectively. When the number of urea additions and F/U molar ratio increased, the gelation time decreased, whereas the viscosity and molecular weight increased. Further, the UF resins prepared with the second urea and 1.0 molar ratio resulted in greater activation energy than those with third urea and 0.7 molar ratio. Tensile shear strength and formaldehyde emission (FE) of the plywood that bonded with these resins increased when the number of urea additions and molar ratio increased. These results suggest that the UF resins prepared with 0.7 molar ratio and third urea addition provide lower adhesion performance and FE than those resins with 1.0 mole ratio and the second urea addition.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.6
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• pp.500-504
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• 2005

Fusion ferritin (heavy chain ferritin, $F_H+$ light chain ferritin, $F_L$), an iron-binding protein, was primarily purified from recombinant Escherichia coli by two-step sonications with urea [1]. Unfolded ferritin was refolded by gel filtration chromatography (GFC) with refolding enhancer, where 50 mM Na-phosphate (pH 7.4) buffer containing additives such as Tween 20, PEG, and L-arginine was used. Ferritin is a multimeric protein that contains approximately 20 monomeric units for full activity. Fusion ferritin was expressed in the form of inclusion bodies (IBs). The IBs were initially solubilized in 4 M urea denaturant. The refolding process was then performed by decreasing the urea concentration on the GFC column to form protein multimers. The combination of the buffer-exchange effect of GFC and the refolding enhancers in refolding buffer resulted in an efficient route for producing properly folded fusion ferritin.

• Journal of the Korean Wood Science and Technology
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• v.45 no.4
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• pp.471-481
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• 2017

As the molecular weight (MW) of urea-formaldehyde (UF) resins had a great impact on their properties, this work was conducted to study effect of analytical parameters of gel permeation chromatography (GPC) on the MW measurement of UF resins. GPC parameters such as flow rate, column, detector temperature, and sample injection temperature were selected to compare number-average molecular weight (Mn), weight-average molecular weight (Mw), molecular weight distribution (MWD) and polydispersity index (PDI) of two UF resins with different viscosities. As expected, UF resin with higher viscosity resulted in greater Mn and Mw than those of low viscosity UF resin. When the flow rate increased, both Mn and Mw of UF resins decreased and MWD became narrower. By contrast, both Mn and Mw increased and MWD became wide when the column, detector, and sample injection temperature increased. The column, detector, and sample injection temperature of $50^{\circ}C$ at a flow rate of $0.5m{\ell}/min$ resulted in the highest MW and broadest MWD for the GPC analysis. These results suggest that the apparent molecular size or a hydrodynamic radius of UF resin molecules dissolved in the mobile phase affect to Mn, Mw and MWD.

• Journal of the Korean Ceramic Society
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• v.42 no.9 s.280
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• pp.618-623
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• 2005

HTGR (High Temperature Gas-Cooled Reactor) is highlighted to next generation power plant for producing the clean hydrogen gas. In this study, the spherical $UO_2$ kernel via $UO_3$ gel particles was prepared by the sol-gel process. Raw material of slightly Acid Deficient Uranyl Nitrate (ADUN) solution, which has pH = 1.10 and $[NO_3]/[U]$ mole ratio = 1.93, was obtained from dissolution of $U_3O_8$ powder with conc.-$HNO_3$. The surface of these spherical $UO_3$ gel particles, which was prepared from the broth solution, consisted of 1 M-uranium, 1 M-HMTA, and urea, were covered with the fine crystallite aggregates, and these particles were so hard that crushed well. But the other $UO_3$ gel particles prepared with the broth solution, consisted of 2 M-uranium, 2 M-HMTA, and urea, have soft surface characteristics and an amorphous phase. This type of $UO_3$ gel particles is some chance of doing possibility of high density from the compaction. The amorphous $UO_3$ gel particles was converted to $U_3O_8$ and then $UO_2$ by calcination at $600^{\circ}C\;in\;4\%\;-\;H_2\;+\;N2$ atmosphere.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.480-483
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• 2003

Fusion ferritin$(F_H+F_L)$, an iron-binding protein, was purified from recombinant E. coli by two-step sonications with urea. Unfolded ferritin was refolded by gel filtration chromatography with various concentration of urea. 50 mM Tris-HCl(pH 8.0) buffers with 1 M to 4 M urea were used in GFC. Objective was to characterize the structure change with urea concentration. Molecular weight was determined using GF-HPLC and RP-HPLC was used to quantify the unfolded and refolded proteins.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.1
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• pp.55-59
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• 1982

With naked barley varieties which are different in their spring habits, variations in seed proteins during ripening were checked by acrylamide gel electrophoresis. In case of 7% acrylamide gel among protein bands ⅰ-band was observed only in both Sedohadaka (intermediate type) and Wanju (spring type) throughout the ripening period, and j-band was detected in all the three varieties until 33 days after heading, but not in Nonsangwa (winter type) thereafter. In case of 6M urea-7% acrylamide gel z-band was traced only in Nonsangwa, contrary to i-band, throughout the ripening period. U-band was observed in all the three varieties until 23 days after heading, but not in Nonsangwa thereafter. X-band showed opposite from u-band. Throughout the ripening period Sedohadaka was significantly more similar in the electrophoretic patterns to Wanju than to Nonsangwa.

• BMB Reports
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• v.39 no.2
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• pp.216-222
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• 2006

In the present study, we compared six different solubilization buffers and optimized two-dimensional electrophoresis (2-DE) conditions for human lymph node proteins. In addition, we developed a simple protocol for 2-D gel storage. Efficient solubilization was obtained with lysis buffers containing (a) 8M urea, 4% CHAPS (3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate), 40 mM Tris base, 65 mM DTT(dithiothreitol) and 0.2% carrier ampholytes; (b) 5M urea, 2M thiourea, 2% CHAPS, 2% SB 3-10 (N-decyl-N, N-dimethyl-3-ammonio-1-propanesulfonate), 40mM Tris base, 65 mM DTT and 0.2% carrier ampholytes or (c) 7M urea, 2M thiourea, 4% CHAPS, 65 mM DTT and 0.2% carrier ampholytes. The optimal protocol for isoelectric focusing (IEF) was accumulated voltage of 16,500 Vh and 0.6% DTT in the rehydration solution. In the experiments conducted for the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), best results were obtained with a doubled concentration (50 mM Tris, 384 mM glycine, 0.2% SDS) of the SDS electrophoresis buffer in the cathodic reservoir as compared to the concentration in the anodic reservoir (25 mM Tris, 192 mM glycine, 0.1% SDS). Among the five protocols tested for gel storing, success was attained when the gels were stored in plastic bags with 50% glycerol. This is the first report describing the successful solubilization and 2D-electrophoresis of proteins from human lymph node tissue and a 2-D gel storage protocol for easy gel handling before mass spectrometry (MS) analysis.

• Macromolecular Research
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• v.17 no.12
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• pp.1015-1020
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• 2009

The role of the water structure present in hydrogels from nutlets of three species of salvias, S. miltiorrhiza (SM), S. sclarea (SS) and S. viridis (SV), was analyzed by differential scanning calorimetry (DSC). The sharp endothermic peaks that appeared at $5.9^{\circ}C$ (SM), $2.8^{\circ}C$ DC (SS) and $1.8^{\circ}C$ (SV) in each 1.0% hydrogel of 10.4-15.8% were not affected by addition of 0.1 M urea and alkali-metal salts. The order-disorder portions in the network were slightly affected by the distribution of freezable and non-freezable water in the hydrogel networks. The SV hydrogel was further used to investigate the effects of additives (0.1-8.0 M urea and 0.1-5.0 M NaCl) on its melting behavior. At 0.5-4.0 M urea and 1.0-3.0 M NaCl, two endothermic peaks appeared, corresponding to unbound (high temperature) and bound (low temperature) water in the gel networks, and eventually merged into one endothermic peak at 5.0-8.0 M urea and 4.0-4.5 M NaCl. After this merger, the endothermic peak shifted to 3.7, 4.0 and $5.6^{\circ}C$ at 5.0, 6.0 and 8.0 M urea, respectively. In the case of NaCl, a combination of peaks that occurred at 4.0-4.5 M were accompanied by a shift to lower temperature (-14.4 and $15.3^{\circ}C$) and the endothermic peak finally disappeared at 5.0 M NaCl due to the strong binding of water in the gel networks.

• Journal of the Korean Wood Science and Technology
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• v.49 no.2
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• pp.169-180
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• 2021

Inherent crystalline domains present in low formaldehyde to urea (F/U) molar ratio urea-formaldehyde (UF) resins are responsible for their poor adhesion in wood-based composite panels. To modify the crystallinity of low molar ratio (LMR) UF resins, this study investigates the additional effect of cellulose nanomaterials (CNMs), such as cellulose microfibrils (CMFs), cellulose nanofibrils (CNFs), and TEMPO-oxidized CNFs (TEMPO-CNFs) on the crystallinity of modified LMR UF resins. First, two modification methods (post-mixing and in situ) were compared for modified LMR UF resins with TEMPO-CNFs. The modified UF resins with TEMPO-CNFs decreased the nonvolatile solid contents, while increasing the viscosity and gel time. However, the in situ modification of UF resins with TEMPO-CNFs showed lower crystallinity than that of post-mixing. Then, the in situ method was compared for all CNMs to modify LMR UF resins. The modified UF resins with CMFs using the in situ method increased nonvolatile solid contents and viscosity but decreased the gel time. The crystallinity of UF resins modified with TEMPO-CNFs was the lowest even though the crystalline domains were not significantly changed for all modified UF resins. These results suggest that these CNMs should be modified to prevent the formation of crystalline domains in LMR UF resins.