• Membrane Journal
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• v.13 no.2
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• pp.110-117
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• 2003

Sulfonated polyimides had been utilized and studied widely as available materials in chloro-alkali electrolysis, cationic exchange resins, and so on. However, a slow decrease in performance during experiments had been reported, which could be attributed to a loss of ionic conductivity related to either a continuous dehydration or polymer degradation. One of main reasons to account for the degradation of sulfonated polymers is the hydrolysis leading to polymer chain scission and decrement of molecular weight. Therefore, the objective of our study was to investigate possible imide cycle and additional ester bond cleavage connected with $SO_3$H presence under hydrated condition. In order to confirm and obtain as clear information as possible about breakages of bonds via $^1H\; and \;^{13}C$ NMR and IR spectroscopic analyses, our study was performed by model compound. Consequently, model compounds with both phthalic and naphthalenic imide ring and ester bonds were synthesized to evaluate the hydrolysis stability of sulfonated polyimide. The experiments were performed for prepared model compounds before and after aging in deionized water at $80^{\circ}C$ and were terminated by lyophilization technique. The aging products were finally analyzed by NMR and IR spectroscopy.

• BMB Reports
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• v.38 no.5
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• pp.591-594
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• 2005

One of the small proteins from Helicobacter pylori, HP1242, was investigated by the solution nuclear magnetic resonance (NMR) spectroscopy. HP1242 is known as a 76-residue conserved hypothetical protein and its function cannot be identified based on sequence homology. Here, the results of the backbone $^1H$, $^{15}N$, and $^{13}C$ resonance assignments of the HP1242 are reported using double- and triple-resonance techniques. About 95% of all of the $^1HN$, $^{15}N$, $^{13}CO$, $^{13}C{\alpha}$, and $^{13}C{\beta}$ resonances that cover 75 non- Proline residues of the 76 residues are clarified through sequential- and specific- assignments. In addition, three helical regions were clearly identified on the basis of the resonance assignments.

• Journal of the Korean Wood Science and Technology
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• v.37 no.1
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• pp.114-120
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• 2009

The bark of Populus alba ${\times}$ glandulosa was collected, air-dried and extracted with 70% aqueous acetone. Then it was successively partitioned with n-hexane, $CH_2Cl_2$, EtOAc and $H_2O$. Repeated Sephadex LH-20 column chromatography and preparative TLC on the EtOAc soluble fraction gave a grandidentatin isomer. The structure was elucidated as grandidentatin A (cis-2-hydroxycyclohexyl 6-O-p-coumaroyl-${\beta}$-D-glucopyranoside) on the basis of spectroscopic evidences such as $^1H$-NMR, $^{13}C$-NMR, 2D-NMR and MALDI TOF-MS spectrum followed by acid hydrolysis. Grandidentatin A was identified here for the first time in Populus alba ${\times}$ glandulosa bark, and to the bset of our knowledge it has not been reported in any other literature.

• Applied Chemistry for Engineering
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• v.26 no.5
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• pp.621-623
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• 2015

This article describes a purification method yielding high purity of MFB produced from DMT production process. Aldehyde functional group of MFB included in side-products were converted to acetal compound via reacting with methanol and further separated. Hydrolysis process of the acetal product was continued under acidic condition and highly pure MFB were obtained with 90% yield. The structure of MFB was analyzed by $^1H$ NMR and $^{13}C$ NMR spectroscopy. Also, the purity of MFB was estimated to be over 99% by GC analysis.

• Korean Journal of Food Science and Technology
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• v.29 no.2
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• pp.204-210
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• 1997

The ethyl acetate (EtOAc) extracts from needles of Pinus densiflora were showed antimicrobial activities against bacteria, yeast and fungi. The antimicrobial active substance of EtOAc extracts were successively purified with solvent fractionation, silica gel adsorption column chromatography and Sephadex LH-20 column chromatography. The purified active substance was isolated as crystals and identified as benzoic acid by $MS,\;^{1}H-NMR\;and\;^{13}C-NMR$. The amount of benzoic acid was 0.608 mg per gram of fresh needle of Pinus densiflora.

• Microbiology and Biotechnology Letters
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• v.28 no.2
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• pp.87-91
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• 2000

In the course of screening for the substances inhibiting apoptosis ofU937 human leukemia cell induced by etoposide, a fungal strain F80834 producing a high level of inhibitor was selected. The inhibitory substance was purified and identified as terrein by spectroscopic methods of UV, EI-MS, IH-NMR, 13C-NMR and DEPT. Terrein showed inhibitory activity of caspase 3, a major protease of apoptosis cascade, with an $IC_{50}$ value of $20\mu\textrm{g}/ml$ after 7 hrs of treatment. It also showed protective effect against cell death with an $IC_{50}$ value of $10\mu\textrm{g}/ml$ on U937 cells induced by etoposide after 24 hrs of treatment, but did not show any cytotoxicity at the same condition without etoposide.

• Applied Biological Chemistry
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• v.41 no.2
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• pp.191-196
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• 1998

The MeOH extract from root of Pulsatilla koreana was showed antimicrobial activities against bacteria and yeast. The antimicrobial active substances of MeOH extract were successfully purified with solvent fractionation, silica gel adsorption column chromatography and Sephadex LH-20 column chromatography. The purified two active substances were isolated by HPLC and identified as 4-hydroxy-3-methoxycinnamic acid and 3,4-dihydroxycinnamic acid by MS, $^{1}H-NMR$ and $^{13}C-NMR$.

• Korean Journal of Food Science and Technology
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• v.27 no.5
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• pp.807-812
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• 1995

The methanol extracts of Aralia elata bark showed antimicrobial activities against bacteria, yeast, fungi. The solvent fractionated acidic fraction that showed the activity was then successively purified with silica gel adsorption column chromatography, Sephadex LH-20 column chromatography, silica gel partition column chromatography, HPLC and TLC. The isolated major active substance was identified as 3,4-dihydroxybenzoic acid by MS, GC-MS, IR, $^{1}H-NMR\;and\;^{13}C-NMR$. The content of 3,4-dihydroxybenzoic acid was 0.869㎎/g in dried bark of Aralia elata.

• Journal of the Korean Chemical Society
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• v.53 no.2
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• pp.159-165
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• 2009

The synthesis of 2-amino-5-substituted-1,3,4-oxadiazoles 4 were carried out from the electrooxidation of semicarbazone 3 at the platinum electrode under controlled potential electrolysis in an undivided cell. This is an environmentally benign method in the field of synthetic organic chemistry. The non-aqueous solvents acetic acid and acetonitrile and a supporting electrolyte lithium perchlorate were used for the electrolysis in the electrooxidation. The products were structurally charecterised by IR, $^1H$-NMR, $^{13}C$-NMR and elemental analysis.

• Elastomers and Composites
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• v.48 no.1
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• pp.85-91
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• 2013

In this study, we synthesized a terpolymer consisting of ethylene, 1-hexene, and styrenic monomer using a metallocene catalyst and cocatalyst ststem. The styrenic monomers empolyed as the third monomer were styrene, p-methylstyrene, and 4-tert-butylstyrene. The structure and composition of the terpolymers were characterized using $^{13}C$ NMR and $^1H$ NMR. Catalytic activity, polymer yield, molecular weight and molecular weight distribution of the terpolymers were analyzed. We also determined the glass transition temperature(Tg), crystallinity and thermal properties of the terpolymers by DMA, WAXS and TGA.