• Title/Summary/Keyword: Carbon 13 NMR

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Methanol Oxidation Effect on Carbon Supported Pt Particles Studied by 13C NMR, XRD, and TEM

  • Han, Kee Sung;Han, Oc Hee
    • Bulletin of the Korean Chemical Society
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    • v.27 no.8
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    • pp.1121-1126
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    • 2006
  • Methanol oxidation effect on carbon supported Pt was investigated as a function of Pt content in a sample which is closely correlated with Pt particle sizes. After prolonged methanol oxidation the Pt particle size did not change within the experimental error ranges. The $^{13}C$ chemical shift and linewidth of CO adsorbed on Pt show non-linear behavior simply due to the Pt particle size difference. The Pt size variation difference between this work and the previous reports of the particle growths is explained by the experimental temperature difference.

Carbon-13 NMR spectra of phytolaccagenin and its Glycosides

  • Woo, Won-Sick;Kang, Sam-Sik;Kazuo-Yamasaki;Osamu-Tanaka
    • Archives of Pharmacal Research
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    • v.1 no.1
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    • pp.21-26
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    • 1978
  • In connection with structure studies on triterpenoid glycosides from Phytolacca plants, full assignments of $^{13}C-NMR signals of phytolaccagenin and its glycosides, phytolaccoside B and E, have been presented.

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A $^{13}C$ NMR Study of 7-Norbornadienyl Cation by Modified Hammett-Brown Equation

  • 박정규;신정휴
    • Bulletin of the Korean Chemical Society
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    • v.20 no.6
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    • pp.667-671
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    • 1999
  • A series of the para-substituted 7-aryl-norbornadienyl cation (3) was prepared in FSO3H/SO2ClF solution at -100℃ and their 13C NMR shifts were measured at -80℃. The plots of the chemical shifts (changes in chemical shifts) of cationic carbon, ΔδC+, aganist our calculated new substituent constant, σc+s, gave an excellent correlation (r=0.994), with a ρc+ value of 12.63. These results indicate that the new substituent constants, σc+s, can be successfully employed to compare the relative charge demand of the carbonium ion by π-and πσ-participation.

In Vivo $^{13}C$-NMR Spectroscopic Study of Polyhydroxyalkanoic Acid Degradation Kinetics in Bacteria

  • Oh, Jung-Sook;Choi, Mun-Hwan;Yoon, Sung-Chul
    • Journal of Microbiology and Biotechnology
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    • v.15 no.6
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    • pp.1330-1336
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    • 2005
  • Polyhydroxyalkanoic acid (PHA) inclusion bodies were analyzed in situ by $^{13}C$-nuclear magnetic resonance ($^{13}C$-NMR) spectroscopy. The PHA inclusion bodies studied were composed of poly(3-hydroxybutyrate) or poly(3hydroxybutyrate-co-4-hydroxybutyrate), which was accumulated in Hydrogenophaga pseudoflava, and medium-chain-length PHA (MCL-PHA), which was accumulated in Pseudomonas fluorescens BM07 from octanoic acid or 11-phenoxyundecanoic acid (11-POU). The quantification of the $^{13}C$-NMR signals was conducted against a standard compound, sodium 2,2-dimethyl-2-silapentane-5-sulfonate (DSS). The chemical shift values for the in vivo NMR spectral peaks agreed well with those for the corresponding purified PHA polymers. The intracellular degradation of the PHA inclusions by intracellular PHA depolymerase(s) was monitored by in vivo NMR spectroscopy and analyzed in terms of first-order reaction kinetics. The H. pseudoflava cells were washed for the degradation experiment, transferred to a degradation medium without a carbon source, but containing 1.0 g/l ammonium sulfate, and cultivated at $35^{\circ}C$ for 72 h. The in vivo NMR spectra were obtained at $70^{\circ}C$ for the short-chain-length PHA cells whereas the spectra for the aliphatic and aromatic MCL-PHA cells were obtained at $50^{\circ}C\;and\;80^{\circ}C$, respectively. For the H. pseudoflava cells, the in vivo NMR kinetics analysis of the PHA degradation resulted in a first-order degradation rate constant of 0.075/h ($r^{2}$=0.94) for the initial 24 h of degradation, which was close to the 0.050/h determined when using a gas chromatographic analysis of chloroform extracts of sulfuric acid/methanol reaction mixtures of dried whole cells. Accordingly, it is suggested that in vivo $^{13}C$-NMR spectroscopy is an important tool for studying intracellular PHA degradation in terms of kinetics.

Comparison of Organic Carbon Composition in Profile by Using Solid 13C CPNMR Spectroscopy in Volcanic Ash Soil

  • Sonn, Yeon Kyu;Kang, Seong Soo;Ha, Sang Keun;Kim, Yoo Hak;Lee, Chang Hoon
    • Korean Journal of Soil Science and Fertilizer
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    • v.46 no.5
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    • pp.391-398
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    • 2013
  • Soil organic carbon (SOC) has the potential to promote the soil quality for sustainability and mitigation of global warming. There is little information on organic carbon composition despite of having resistance of carbon degradation in soil. In this study, to understand the effect of volcanic ash on organic carbon composition and quantity in soil, we investigated characteristics of volcanic soil and compared organic carbon composition of soil and humic extract by using $^{13}C$-CPMAS-NMR spectra under soil profiles of Namweon series in Jeju. SOC contents of inner soil profiles were 134.8, 101.3, and 27.4 g C $kg^{-1}$ at the layer of depth 10-20, 70-80 and 90-100 cm, respectively. These layers were significantly different to soil pH, oxalate Al contents, and soil moisture contents. Alkyl C/O-alkyl C ratio in soil was higher than that of humic extracts, which was decreased below soil depth. Aromaticity of soil and humic extract was ranged from 29-38 and 24-32%, which was highest at the humic extract of 70-80 cm in soil depth. These results indicate that the changes of SOC in volcanic ash soil resulted from alteration of organic composition by pyrolysis and stability of organic carbon by allophane in volcanic ash soil.

13C-NMR Spectroscopy of Urea-Formaldehyde Resin Adhesives with Different Formaldehyde/Urea Mole Ratios

  • Park, Byung-Dae;Lee, Sang M.;Park, Jong-Young
    • Journal of the Korean Wood Science and Technology
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    • v.36 no.2
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    • pp.63-72
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    • 2008
  • As a part of abating formaldehyde emission of urea-formaldehyde (UF) resin adhesive, this study was conducted to investigate chemical structures of UF resin adhesives with different formaldehyde/urea (F/U) mole ratios, using carbon-13 nuclear magnetic resonance ($^{13}C$-NMR) spectroscopy. UF resin adhesives were synthesized at four different F/U mole ratios such as 1.6, 1.4, 1.2, and 1.0 for the analysis. The analysis $^{13}C$-NMR spectroscopy showed that UF resin adhesives with higher F/U mole ratios (i.e., 1.6 and 1.4) had two distinctive peaks, indicating the presence of dimethylene ether linkages and methylene glycols, a dissolved form of free formaldehyde. But, these peaks were not detected at the UF resins with lower F/U mole ratios (i.e., 1.2 and 1.0). These chemical structures present at the UF resins with higher F/U mole ratios indicated that UF resin adhesive with higher F/U mole ratio had a greater contribution to the formaldehyde emission than that of lower F/U mole ratio. Uronic species were detected for all UF resins regardless of F/U mole ratios.

$^{13}$C NMR Relaxation Study of Internal Rotation of Methyl Groups-Spin-Rotational Relaxation of methyl Carbon-13 in 2-bromo-p-xylene, 2,5-dimethylanisole and 2,5-dimethylaniline

  • Lee, Jo-Woong;Cho, Chull-Hyung;Park, Seong-Kyu;Jo, Byung-Wook;Ro, Bong-Oh;Choe, Sung-Hyu
    • Bulletin of the Korean Chemical Society
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    • v.8 no.2
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    • pp.73-79
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    • 1987
  • In this work we have investigated temperature dependence of spin-rotational relaxation rate, $(1/T_1)_{SR}$, of methyl carbon-13's in 2-bromo-p-xylene, 2,5-dimethylaniline, and 2,5-dimethylanisole and have found that temperature behaviors of two methyl carbon-13's in ortho- and meta-position, respectively, are substantially different. It has been confirmed that the modified Burke-Chan model proposed by Park et al. can nicely explain different temperature dependence of $(1/T_1)_{SR}$ for these two methyl carbon-13's while the original Burke-Chan model fails to do so.

Elucidation of the Vulcanization Structures of Filled cis-1,4-Polybutadiene Rubber by Solid State Carbon-13 NMR Spectroscopy (고체상태 NMR을 이용한 cis-1,4-polybutadiene 충진고무의 가황가교 구조 규명)

  • Kim, Su-Dong;Park, Eun-Kyung;Ryu, Ju-Whan
    • Elastomers and Composites
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    • v.43 no.4
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    • pp.281-287
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    • 2008
  • Using solid state $^{13}C$ NMR, polybutadiene rubber vulcanizates were qualitatively and quantitatively analyzed. In the filled conventional system of BR vulcanizate accelerated with TBBS, addition to the olefinic double bond and substitution in the $\alpha$ position to the double bond occurred simultaneously. Also the latter $\alpha$ substitution reaction was faster than the former addition reaction at initial reaction time. In addition, it was suggested that double bond-addition-polysulfide structures might be modified into 5-membered and 6-membered cyclic structures in overcure time. These chain modifications were correlated with the decrease in the chemical crosslink density in overcure time.

Spectroscopic Analysis of Alkylbenzenes as Synthetic Lubricant Base Oils (합성 윤활기유로서의 알킬벤젠의 분광분석)

  • Choi, Ju-Hwan;Jeong, Hyuk;Kim, Hai-Dong
    • Analytical Science and Technology
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    • v.10 no.2
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    • pp.139-145
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    • 1997
  • Alkylbenzenes used as synthetic lubricant base oils have been analyzed to find the quantity of mono- and di-substituted alkyl aromatic hydrocarbon compositions and the number of carbon atoms in alkyl chains by $^{13}C$-NMR, near-infrared, and UV-Vis spectroscopy. Also, linear long chain alkylated benzene in the engine lubricants was analyzed quantitatively by infrared spectroscopy.

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Isolation and Characterization of Aquatic Humic Acid and Fulvic Acid (수질계의 Humic Acid와 Fulvic Acid의 분리 및 특성)

  • Rhee, Dong Seok
    • Analytical Science and Technology
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    • v.15 no.1
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    • pp.36-42
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    • 2002
  • The dissolved organic carbon extracted from groundwater is separated into humic acid and fulvic acid. They are characterized for their chemical composition, spectroscopic characteristics using UV/VIS, IR and solid state $^{13}C-NMR$ spectroscopy, proton exchange capacity and molecular size distribution. The results are comparable with the literature data. The study explains that the aquatic humic and fulvic acid in this experiment are site-specipic and polydisperse natural organic matter with considerable proton exchange capacity.