• The Journal of the Petrological Society of Korea
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• v.10 no.3
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• pp.233-245
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• 2001

With the advent of super-conducting magnet, NMR spectroscopy becomes a very important tool in geology as well as in chemistry. $^{29}Si$ and $^{27}Al$ which are the main components of minerals and contain structural informations, are useful major targets for the NMR study in geology, but some other elements including alkali cations such as $^{23}Na$ are also one of them. NMR can be applied to many different fields. For example, it can be applied to study smaller range of structure (in molecular level) than XRD and TEM. NMR provides us with structural informations such as order-disorder in Al and Si distribution, oxygen coordination number, and distribution of other cations. Another important information that we can obtain from NMR is not only the static structural informations, but also the molecular dynamics. This dynamic informations of molecules also enable us to figure out the frequency of molecular motion and activation energy. Structure of amorphous minerals and chemistry and structure of natural organic materials are also studied by NMR.

• Bulletin of the Korean Chemical Society
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• v.30 no.9
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• pp.2007-2010
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• 2009

Donepezil hydrochloride is a reversible acetylcholinesterase inhibitor that is used in the treatment of Alzheimer’s disease to improve the cognitive performance. It shows different crystalline forms including hydrates. Therefore, it is very important to confirm the polymorphic forms in the formulations of pharmaceutical materials because polymorphs of the same drug often exhibit significant differences in solubility, bioavailability, processability and physical/chemical stability. In this paper, four different forms of donepezil hydrochloride were prepared and characterized using X-ray powder diffraction, Fourier transform infrared, and solid-state nuclear magnetic resonance (NMR) spectroscopy. This study showed that solid-state NMR spectroscopy is a powerful technique for obtaining structural information and the polymorphology of pharmaceutical solids.

• 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.

• Journal of the Korean Magnetic Resonance Society
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• v.8 no.1
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• pp.19-27
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• 2004

C-terminal fragments of APP (APP-CTs), that contain complete Abeta sequence, are found in neuritic plaques, neurofibrillary tangles and the cytosol of lymphoblastoid cells obtained from AD patients. CT16, Lys649-Asp664 (KKQYTSIHHGVVEVD) has been known as the most toxic part in the C-terminal fragment of amyloid precursor protein (APP). The solution structure of CT16 was investigated using NMR spectroscopy in various membrane-mimicking environments. According to Circular Dichroim (CD) spectra, CT16 has a random structure in aqueous solution, while conformational change was induced by addition of TFE and SDS micelle. Tertiary structure as determined by NMR spectroscopy shows that CT16 has a ${\beta}$-turn conformation in trifluoroethanol-containing aqueous solution.

• Journal of the Korean Applied Science and Technology
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• v.36 no.1
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• pp.84-89
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• 2019

To characterize the molecular structure of BzO-gal synthesized using Escherichia coli ${\beta}$-gal, NMR ($^1H$- and $^{13}C$-) spectroscopy and mass spectrometry of BzO-gal were conducted. $^1H$ NMR spectrum of BzO-gal showed multiple peaks corresponding to the galactosyl group, which is an evidence of galactosylation on BzOH. Five proton peaks around the aromatic region at ${\delta}_H$ 7.43 ~ 7.24 ppm and 2 peaks from ${\delta}_H$ 4.93 and 4.67 ppm were evidence of the presence of the benzyl group. Seven proton peaks at ${\delta}_H$ 4.32 ~ 3.46 ppm showed the presence of a monosaccharide and were indicative of galactosylation on BzOH. $^{13}C$ NMR spectrum also revealed the presence of 11 carbons suggestive of BzO-gal. The mass value (sodium adduct ion of BzO-gal, m/z = 293.0994) from mass spectrometry analysis of BzO-gal, and $^1H$ and $^{13}C$ NMR spectral data were in good agreement with the expecting structure of BzO-gal. We are expecting that through future study it will eventually be able to develop a new additive of low cytotoxicity.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.531-535
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• 2011

It was regarded that the $^{31}P$ resonances of inherent nucleotides in $F_1$-ATPase (EF1), as large as 380KDa, could not be observed by $^{31}P$ NMR spectroscopy. However, our $^{31}P$ NMR spectroscopy could differentiate between different nucleotide binding sites on EF1 from Escherichia coli. When EF1 was prepared in the absence of $Mg^{2+}$, EF1 contained only ADP. Multiple $^{31}P$ resonances from $\beta$-phosphates of ADP bound to the EF1 were observed from the enzyme prepared without $Mg^{2+}$, suggesting asymmetry or flexibility amongst nucleotide binding sites. $^{31}P$ resonances from enzyme bound ATP could be observed only from EF1, when the enzyme was prepared in the presence of $Mg^{2+}$. This $Mg^{2+}$ dependent ATP binding was very tight that, once bound, nucleotide could not be removed even after removal of $Mg^{2+}$. $^{31}P$ NMR proved to be a valuable tool for investigating phosphorous related enzymes.

• Bulletin of the Korean Chemical Society
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• v.29 no.2
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• pp.405-407
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• 2008

Functionalized SAB-15 samples by octadecyltrimethoxysilane (OTC) were studied by 13C magic angle spinning (MAS) cross polarization (CP) nuclear magnetic resonance (NMR) spectroscopy. In the SBA-15 sample fully functionalized by 3-aminopropyltrimethoxysilane (APS) and OTC in 1:1 molar ratio, octadecyl chains were observed to have, on average, more trans conformation than those in the SBA-15 samples fully modified by OTC only. Our results confirm that long chain molecules tend to organize themselves better in the co-presence of short chain molecules on the surface of mesoporous materials by packing of the different length chains in an interdigitized fashion even when the short chains are long enough to have three carbons and a functional group at the ends. In addition, our results indicate that solid-state 13C CP MAS NMR spectroscopy is a simple and non-destructive method to probe the molecular structures of the domains composed of long alkyl chains.

• ETRI Journal
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• v.46 no.4
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• pp.581-594
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• 2024

In this study, a planar printed circuit board (PCB) coil with FR4 substrate was designed and simulated using the finite element method, and the results were analyzed in the frequency domain. This coil can be used in wireless power transfer (WPT) as a transmitter or receiver, eliminating wires. It can also be used as the receiver in radio frequency energy-harvesting (RF-EH) systems by optimizing the planar PCB coil to convert radio-wave energy into electricity, and it can be employed as an excitation (transmitter) or receiver coil in nuclear magnetic resonance (NMR) spectroscopy. This PCB coil can replace the conventional coil, yielding a reduced occupied volume, a fine-tuned design, reduced weight, and increased efficiency. Based on the calculated gain, power, and electromagnetic and electric field results, this planar PCB coil can be implemented in WPT, NMR spectroscopy, and RF-EH devices with minor changes. In applications such as NMR spectroscopy, it can be used as a transceiver planar PCB coil. In this design, at frequencies of 915 MHz and 40 MHz with 5 mm between coils, we received powers of 287.3 μW and 480 μW, respectively, which are suitable for an NMR coil or RF-EH system.

• Bulletin of the Korean Chemical Society
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• v.32 no.11
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• pp.4016-4020
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• 2011

A number of mimetic peptides of apolipoprotein A-I, a major component for high density lipoproteins (HDL), were screened from the phase-displayed random peptide library by utilizing monoclonal antibodies (A12). A mimetic peptide for A12 epitope against apolipoprotein A-I was selected as FVLVRDTFPSSVCCP(pA2) exhibiting 45% homology with Apo A-I in the BLAST search. Solution structure determination of this mimotope was made by using 2D-NMR data and NMR-based distance geometry (DG)/molecular dynamic calculations. The resulting DG structures had low penalty value of 0.4-0.6 ${\AA}^2$ and the total RMSD of 0.7-1.7 ${\AA}$. The mimotope pA2 exhibited a characteristic ${\beta}$-turn conformation from Val[2] to Phe[8] near Pro[9] residue.

• Journal of the Korean Magnetic Resonance Society
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• v.10 no.1
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• pp.38-45
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• 2006

The NMR and MS techniques were applied to identification and quantitative analysis of oligomers in a commercialized poly (trimethylene terephthalate). Oligomers in a commercialized poly (trimethylene terephthalate) were extracted via a dissolving and reprecipitation method. Analysis of the components of the extract using NMR and MS revealed that it contained mainly cyclic oligomers with degrees of polymerization of 2, 4 and 5 (dimer, tetramer and pentamer). Trimer and cyclic oligomers with degrees of polymerization of more than 6 were not found in the extract in the present study. Quantitative analysis of dimer was performed by NMR spectroscopy.