• Journal of the Korean Magnetic Resonance Society
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• v.11 no.1
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• pp.42-47
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• 2007

Several hydrotalcite compounds calcined with different temperature for applications in a chlorine resistant textile were prepared, and its structural changes in dependence on the temperature were studied by using $^{27}Al$ solid-state nuclear magnetic resonance(NMR) spectroscopy. We found that the Al coordination was partly lowered from octahedral to tetrahedral site as the calcined temperature goes up. And we also investigated the hydrotalcite-treated textile for chlorine resistance by using $^{27}Al$ solid-state NMR spectroscopy.

• Bulletin of the Korean Chemical Society
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• v.30 no.5
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• pp.1077-1079
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• 2009

To minimize the variance in the quantification of solid-state phases in powder samples, gently placing polycrystalline samples one next to another directly in a sample holder is better than trying to mix them homogeneously prior to transferring to a sample holder. However, the solid-state cross polarization-magic angle spinning (CP-MAS) nuclear magnetic resonance (NMR) spectroscopy results demonstrated that it is essential in this sampling method to place all the samples in the location of consistent signal sensitivity. The same sampling method may be employed in other spectroscopic quantification techniques of solid-state phases if the method to limit the sample to the location with uniform signal sensitivity in the sample holder is adapted to each technique.

• Bulletin of the Korean Chemical Society
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• v.30 no.1
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• pp.149-152
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• 2009

Hydrotalcites are anionic clays that are quite prevalent in nature and their importance is growing more and more because of their very wide range of potential applications and uses. Understanding the structural and compositional changes that occur on the molecular scale during the thermal decomposition of hydrotalcite compounds is essential for the basic prediction and comprehensive understanding of the behavior and technical application of these materials. In this study, several hydrotalcite compounds calcined at different temperatures for applications in a chlorine resistant textile were prepared and 27-Aluminm solid-state nuclear magnetic resonance (NMR) spectroscopy was used as a tool to study their local structure and behavior. The changes in the Al coordination of the hydrotalcite compounds were investigated with one dimensional (1D) solid-state magic angle spinning (MAS) NMR spectroscopy. The two broad resonances arising from the structurally different Al coordinations of these compounds were clearly resolved by two dimensional (2D) triple quantum magic angle spinning (3QMAS) NMR spectroscopy.

• 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.

• Bulletin of the Korean Chemical Society
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• v.27 no.3
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• pp.386-388
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• 2006

Membrane proteins in highly oriented lipid bilayer samples are useful for membrane protein structure determination. We used in the past planar lipid bilayers which were aligned and supported on the glass slide. These samples were mechanically aligned in a magnetic field. However, these stacks of glass slides with planar lipid bilayers are not well suited for use with a commercial solid-state NMR probe with a round coil. Therefore, a homebuilt solid-state NMR probe was built and used with a stack of thin glass plates wherein the RF coil was wrapped directly around the flat square sample. Recently, we began to use magnetically aligned bicelles that are suitable for the structure determination of membrane proteins by solid-state NMR spectroscopy without any effort to build a flat square coil probe. These bicelle samples are well suited for use with a commercial solidstate NMR probe with a round coil, are very easy to prepare and are very stable, so that they can be kept for more than a year. In this paper, we present the solid-state NMR spectra of optimized and magnetically oriented bicelle samples of membrane proteins.

• Polymer Science and Technology
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• v.4 no.4
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• pp.287-304
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• 1993

• Journal of the Korean Magnetic Resonance Society
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• v.1 no.1
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• pp.45-58
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• 1997

Heteropoly compounds, H3PMo12O40, CsxH3-xPMo12O40, and vanadium containing heteropoly compound were characterized by Solid-state broad line 1H MAS NMR, 31P MAS NMR, and High Speed MAS 51V NMR spectroscopy of quadrupolar nuclei. The effects of calcination, dehydration, and the number of protons on the structure of heteropoly compounds were studied. The results of this study demonstrate that these Solid-state NMR techniques are very useful tools to study heteropoly compounds.

• Analytical Science and Technology
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• v.17 no.5
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• pp.388-392
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• 2004

Structural studies of membrane proteins, importantly involving interpretation of genomics information, many signaling pathway and major drug target for drug discovery, are having difficulty in characterizing the function using conventional solution nmr spectroscopy and x-ray crystallography because phospholipid bilayers hindered fast tumbling and crystallization. Here, we studied the structure of the pf1 coat protein in oriented phospholipid bilayers by home-built solid-state NMR probe. Bacteriophage pf1 was purified from Paeudomonas Aeruginosa and coat protein of bacteriophage pf1 was isolated from DNA and other proteins.

• Journal of the Korean Magnetic Resonance Society
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• v.6 no.2
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• pp.142-154
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• 2002

One of the oldest, still unsolved, and often ignored problems in magnetic resonance remains the issue of how to observe undistorted, normal one-dimensional spectra where the frequencies and their relative intensities represent faithfully the distribution of spins and sites in the sample within the magnet. Often distortions in these parameters are accepted, as the price of sensitivity enhancement, or because it is unclear just how these distortions might be avoided. Surprisingly enough, the problem is exacerbated by the use of modern techniques of pulsed Fourier transform NMR. Noise spectroscopy is an approach to solving the problem of distorted NMR spectra, which is largely under appreciated; it promises virtually "unlimited" distortionless bandwidths without costly hardware investments. Nonetheless, its exploitation remains limited. We will discuss why noise spectroscopy belongs in the arsenal of tricks spectroscopists should be aware of, show examples where its use is essential if accurate, quantitative NMR is to be expected, and discuss some recent approaches which extend its applicability yet further, particularly in solid state NMR and in applications to quadrupolar nuclear spins.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.347-347
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• 2006

Polymers containing poly(vinyl phosphonic) acid segments are promising candidates to be used as proton conducting membranes. Solid state NMR spectroscopy represents an ideal probe of proton motion on the molecular level, because it allows us to selectively detect the nuclei of interest. In this paper, we apply solid state NMR methods to poly(vinyl phosphonic) acid in order to demonstrate that the proton conduction of poly(vinyl phosphonic acid) results from P-OH proton through hydrogen bonding and that the condensation of phosphonic acid leads to decrease in proton conductivity. $^{1}H\;and\;^{31}P$ solid state NMR experiments are supported by quantum chemical computation of NMR parameters.