• Bulletin of the Korean Chemical Society
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• v.8 no.3
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• pp.144-145
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• 1987

The relative stability as function of geometry in the rigid tricyclopropylcarbinyl cations with varied bond angle (${\alpha}$) between the plane of cyclopropane ring and the bond connecting cyclopropane ring to cationic carbon was examined by $^{19}F$ nmr spectroscopy. 7-p-Fluorophenyltricyclo[2.2.2.$0^{2,6}$]octan-7-yl(4) and 8-p-fluorophenyltricyclo[3.2.2.$0^{2,7}$]nonan-8-yl cation (8) were generated from corresponding tertiary alcohols under stable ion conditions, and their $^{19}F$ chemical shifts were compared with those of model compounds such as 7-nortricyclyl cation (3) and tricyclo[3.3.1.$0^{2,7}$]octan-8-yl cation (7). Consequently, it is concluded that the varied orientation of bond angle (${\alpha}$) within in the bisected conformation does not affect degree of the charge delocalization into cyclopropane ring.

• Bulletin of the Korean Chemical Society
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• v.18 no.10
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• pp.1094-1099
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• 1997

The rotational barriers of thioacetamide (TA) and acetamide (AA) were studied using the ab-initio molecular orbital theory and NMR spectroscopy. The calculated rotational barriers using MP2/6-31G**//MP2/6-31G** for TA was 72.26 kJ/mol and 58.19 kJ/mol for AA, respectively. These results are good agreement with the experimental data. The tendency for the change of structural parameters is consistent with the result of formamide. In both amides, the rotational barrier arises from the pyramidalization of nitrogen. The chemical shifts of both amides are shifted upfield when temperature is raised, which confirms pyramidalization of nitrogen. The lineshape of 1H-NMR spectra of TA shows quintet which is contributed from two triplet spectra. This means that the distribution of electrons around the nitrogen is rather symmetric. Ab-initio calculations of electric field gradient for both amides confirm the above results. The above experimental results are well understood by Keith's view on thioamides, which excludes the contribution of resonance structure and considers the origin of rotational barrier to be the same in both thioamides and in corresponding amides.

• Bulletin of the Korean Chemical Society
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• v.19 no.5
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• pp.533-539
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• 1998

A magnetic film was deposited on a slide glass substrate from aqueous solutions of $FeCl_2$ and $NaNO_2$ at 363 K. XRD analysis showed that the film was polycrystalline magnetite $(Fe_{3(1-{\sigma})}O_4)$ without impurity phase. The lattice constant was 0.8390 nm. Mossbauer spectrum of the film could be deconvoluted by the following parameters: isomer shifts for tetrahedral $(T_d)$ and octahedral $(O_h)$ sites are 0.28 and 0.68 mm/s, respectively, and corresponding magnetic hyperfine fields are 490 and 458 kOe, respectively. The estimated chemical formula of the film by the peak intensity of Mossbauer spectrum was $Fe_{2.95}O_4$. Low temperature transition of the magnetite (Verwey transition) was not detected in resistivity measurement of the film. Properties of the film were discussed with those of pressed pellet and single crystal of synthetic magnetites. On the surface of the film, magnetite particles of about 0.2 μm in diameter were identified by noncontact atomic force microscopy (NAFM) and magnetic force microscopy (MFM).

• Bulletin of the Korean Chemical Society
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• v.16 no.4
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• pp.331-336
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• 1995

The macroscopic and microscopic redox potentials of tetrahemoprotein, cytochrome c3 from Desulfovibrio vulgaris(Hildenborough) (DvH) were estimated from 1H NMR and differential pulse polarography(DPP). Five sets of NMR resonances were confirmed by a redox titration. They represent cytochrome c3 molecules in five macroscopic redox states. The electron transfer in cytochrome c3 involves four consecutive one-electron steps. The saturation transfer method was used to determine the chemical shifts of eight heme methyl resonances in five different oxidation states. Thirty two microscopic redox potentials were estimated. The results showed the presence of a strong positive interaction between a pair of particular hemes. Comparing the results with those of Desulfovibrio vulgaris Miyazaki F (DvMF), it was observed that the two proteins resemble each other in overall redox pattern, but there is small difference in the relative redox potentials of four hemes.

• Bulletin of the Korean Chemical Society
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• v.9 no.6
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• pp.365-368
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• 1988

Coordination chemistry of organotin(IV) dithiocarbamate complexes has been examined in terms of far infrared and $^{119}Sn$-NMR spectroscopies. Although the Sn-S stretching vibrational bands of the complex could not be correlated with the bonding nature of the dithiocarbamate ligand, $^{119}Sn$ chemical shifts were sensitive enough to distinguish clearly the coordination number of tin, and as such the bonding mode of the dithiocarbamate ligand could be indentified to be monodentate or bidentate. Thus the $^{119}Sn$-NMR study on new cyclohexyltin(IV) dithiocarbamate complexes along with the known complexes suggests that the bonding mode of the dithiocarbamate ligands and the consequent coordination number of tin are determined mainly by the inductive effects of the organic groups attached to the tin atom.

• Applied Biological Chemistry
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• v.48 no.3
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• pp.267-272
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• 2005

trans-Cinnamaldehyde, a major component of Cinnamomum cassia, was quantitatively analyzed using the $^1H-NMR$ spectrometry. Applicability of this method was confirmed through observing the variation of chemical shift in the $^1H-NMR$ spectrum of t-cinnamaldehyde and the integration value according to various sample concentrations or running temperatures. When the $^1H-NMR$ spectrometry was run for t-cinnamaldehyde (7.1429 mg/ml) at 19, 25, 30, 40 and $50^{\circ}C$, the chemical shifts of the doublet methine signal due to an aldehyde group were observed at 9.7202, 9.7184, 9.7169, 9.7142 and 9.7124 ppm, respectively, to imply that the running temperature had no significant variation in the chemical shift of the signal. The integration values of the signal were $1.37\;(19^{\circ}C),\;1.37\;(25^{\circ}C),\;1.37\;(30^{\circ}C),\;1.37(40^{\circ}C)$ and $1.37(50^{\circ}C)$, respectively, to also indicate running temperature gave no effect on the integration value. When the sample solutions with various concentrations such as 0.4464, 0.8929, 1.7857, 3.5714, 7.1429 and 14.286 mg/ml were respectively measured for the $^1H-NMR$ at $25^{\circ}C$, the chemical shifts of the aldehyde group were observed at 9.7206, 9.7201, 9.7196, 9.7192, 9.7185 and 9.7174 ppm. Even though the signal was slightly shifted to the high field in proportion to the increase of sample concentration, the alteration was not significant enough to applicate this method. The calibration curve for integration values of the doublet methine signal due to the aldehyde group vs the sample concentration was linear and showed very high regression rate ($r^2=1.0000$). Meantime, the $^1H-NMR$ spectra (7.1429 mg/ml $CDCl_3,\;25^{\circ}C$) of t-cinnamaldehyde and t-2-methoxycinnamaldehyde, another constituent of Cinnamomum cassia, showed the chemical shifts of the aldehyde group as ${\delta}_H$ 9.7174 (9.7078, 9.7270) for the former compound and ${\delta}_H$ 9.6936 (9.6839, 9.7032) for the latter one. The difference of the chemical shift between two compounds was big enough to be distinguished using the NMR spectrometer with 0.45 Hz of resolution. The contents of cinnamaldehyde in Cinnamomum cassia, which were respectively extracted with n-hexane, $CHCl_3$, and EtOAc, were determiend as 94.2 \;mg/g (0.94%), 137.6 mg/g (1.38%) and 140.1 mg/g(1.40%) t-cinnamaldehyde in each extract, respectively, by using the above method.

• Journal of Ginseng Research
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• v.20 no.1
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• pp.111-112
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• 1996

The chemical shifts of C-21 and C-23 in the $^{13}C$-NMR for (20R)-protopanaxatriol, (20R)-ginsenoside $Rh_1$ and (20R)-ginsenoside $Rg_3$ were revised by employing some extensive 2D-NMR techniques.

• Journal of the Korean Chemical Society
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• v.26 no.5
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• pp.291-295
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• 1982

$^{13}C$resonances of carbonyl and various alkyl groups in amides are found to shift down-field on the interaction with lithium salts and it is shown that lithium ion binds directly to the carbonyl group in amides. The magnitudes of the $^{13}C$ chemical shifts of various amides depend not only on the size of alkyl groups in amides but also on the interaction with anion. The change of $^{13}C$chemical shift of amide in LiCl is smaller than that in$LiClO_4$ due to the difference of the charge density of the anion.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3581-3588
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• 2012

A new series of acyclic mononuclear gadolinium(III) complexes have been prepared by Schiff-base condensation derived from 5-methylsalicylaldehyde, diethylenetriamine, tris(2-aminoethyl) amine, triethylenetetramine, N,N-bis(3-aminopropyl)ethylene diamine, N,N-bis(aminopropyl) piperazine, and gadolinium nitrate. All the complexes were characterized by elemental and spectral analyses. Electronic spectra of the complexes show azomethine (CH=N) within the range of 410-420 nm. The fluorescence efficiency of Gd(III) ion in the cavity was completely quenched by the higher chain length ligands. Electrochemical studies of the complexes show irreversible one electron reduction process around -2.15 to -1.60 V The reduction potential of gadolinium(III) complexes shifts towards anodic directions respectively upon increasing the chain length. The catalytic activity of the gadolinium(III) complexes on the hydrolysis of 4-nitrophenylphosphate was determined. All gadolinium(III) complexes were screened for antibacterial activity.

• Journal of Microbiology and Biotechnology
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• v.24 no.2
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• pp.270-279
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• 2014

Microbial community shifts, associated with performance data, were investigated in an anaerobic batch digester treating high-solid food waste under mesophilic conditions using, a combination of molecular techniques and chemical analysis methods. The batch process was successfully operated with an organic removal efficiency of 44.5% associated with a biogas yield of 0.82 L/g $VS_{removal}$. Microbial community structures were examined by denaturing gel gradient electrophoresis. Clostridium and Symbiobacterium organisms were suggested to be mainly responsible for the organic matter catabolism in hydrolysis and acidogenesis reactions. The dynamics of archaeal and methanogenic populations were monitored using real-time PCR targeting 16S rRNA genes. Methanosarcina was the predominant methanogen, suggesting that the methanogenesis took place mainly via an aceticlastic pathway. Hydrogenotrophic methanogens were also supported in high-solid anaerobic digestion of food waste through syntrophism with syntrophic bacterium. Microbial community shifts showed good agreement with the performance parameters in anaerobic digestion, implying the possibility of diagnosing a high-solid anaerobic digestion process by monitoring microbial community shifts. On the other hand, the batch results could be relevant to the start-up period of a continuous system and could also provide useful information to set up a continuous operation.