• Journal of the Korean Magnetic Resonance Society
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• v.22 no.4
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• pp.107-114
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• 2018

In this exploration, the nuclear magnetic resonance of the $^{207}Pb$ nucleus in $PbWO_4:Mn^{2+}$ and $PbWO_4:Dy^{3+}$ Single Crystals using FT-NMR spectrometer is investigated. The line width of the resonance line for the $^{207}Pb$ nucleus decreases as temperature increases due to motional narrowing. The chemical shift of $^{207}Pb$ NMR spectra also increases as temperature decreases for both crystals. The spinlattice relaxation times $T_1$ of $^{39}K$ nucleus were calculated as a function of temperature (180 K~400 K). The $T_1$ of $^{207}Pb$ nucleus decreases as temperature increases. The dominant relaxation mechanism at the studied temperature range can be deduced as the Raman process, which is the coupling between lattice vibrations and the nuclear spins. This deduction is substantiated by the fact that the nuclear spin-lattice relaxation rate $1/T_1$ of the $^{207}Pb$ nucleus in $PbWO_4:Mn^{2+}$ and $PbWO_4:Dy^{3+}$ single crystal is proportional to $T^2$, or temperature squared. The activation energies for the $^{207}Pb$ nucleus in $PbWO_4:Mn^{2+}$ and $PbWO_4:Dy^{3+}$ single crystals are $E_a=49{\pm}1meV$ and $E_a=47{\pm}2meV$, respectively.

• Korean Journal of Food Science and Technology
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• v.31 no.5
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• pp.1386-1391
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• 1999

The methanol extract of Gardenia jasminoides Ellis showed antimicrobial activity against bacteria and yeasts. The extract was successively purified with solvent fractionation, silica gel adsorption column chromatography, Sephadex LH-20 column chromatography, octadecylsilane column chromatography. The purified active substance was isolated by high performance liquid chromatography. The isolated compound was 3,4-dihydroxybenzoic acid which was determined by mass spectrometer, gas chromatograph-mass spectrometer, $^{1}H-nuclear$ magnetic resonance, $^{13}C-nuclear$ magnetic resonance and two-dimensional nuclear magnetic resonance. The content of 3,4-dihydroxybenzoic acid was $32.7\;{\mu}g/g$ in dried fruits of Gardenia jasminoides Ellis.

• Carbon letters
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• v.27
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• pp.90-97
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• 2018

Electromagnetic interference (EMI) shielding is an important issue in modern daily life due to the increasing prevalence of electronic devices and their compact design. This study estimated EMI-shielding effect (EMI-SE) of small ($8-14{\times}17mm$) Hanji (Korean traditional paper) doped with carbon nanotubes (CNTs) and compared to Hanji without CNT using $^2H$ (92.1 MHz) and $^{23}Na$ (158.7 MHz) nuclear magnetic resonance (NMR) peak area data obtained from 1 M NaCl in $D_2O$ samples in capillary tubes that were wrapped in the Hanji samples. The simpler method of using the variation of reflected power and tuning frequency by inserting the sample into an NMR coil was also tested at 242.9, 158.7, and 92.1 MHz. Overall, EMI shielding was relatively more effective at the higher frequencies. Our results validated that NMR methods to be useful to evaluate EMI-SE, particularly for small, flexible shielding materials, and demonstrated that EMI shielding by absorption is dominant in Hanji mixed with CNT.

• Progress in Superconductivity and Cryogenics
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• v.24 no.3
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• pp.24-29
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• 2022

One of the recent proposals with nuclear magnetic resonance (NMR) is a multi-bore NMR which consists of array of magnets which could present possibilities to quickly cope with pandemic virus by multiple inspection of virus samples. Low temperature superconductor (LTS) can be a candidate for mass production of the magnet due to its low price in fabrication as well as operation by applying the helium zero boil-off technology. However, training feature of LTS magnet still hinders the low cost operation due to multiple boil-offs during premature quenches. Thus in this paper, LTS magnet with low mechanical stress is designed targeting the "training-free" LTS magnet for mass production of magnet array for multi-bore NMR. A thorough process of an LTS magnet design is conducted, including the analyses as the followings: electromagnetics, mechanical stress, cryogenics, stability, and protection. The magnet specification was set to 4.7 T in a winding bore of 85 mm, corresponding to the MR frequency of 200 MHz. The stress level is tolerable with respect to the wire yield strength and epoxy crack where mechanical disturbance is less than the minimum quench energy.

• Journal of the Korean Magnetic Resonance Society
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• v.23 no.1
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• pp.12-19
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• 2019

A former study has shown that the spin-lattice relaxation time ($T_1$) in cancerous prostate tissue had enhanced contrast at an ultra-low magnetic field, $132{\mu}T$. To study the field dependence and the origin of the contrast we measured $T_1$ in pairs of ex-vivo prostate tissues at the Earth's magnetic field. A portable and coil-based nuclear magnetic resonance (NMR) system was adopted for $T_1$ measurements at $40{\mu}T$. The $T_1$ contrast, ${\delta}=1-T_1$ (more cancer)/$T_1$(less cancer), was calculated from each pair. Additionally, we performed pathological examinations such as Gleason's score, cell proliferation index, and micro-vessel density (MVD), to quantify correlations between the pathological parameters and $T_1$ of the cancerous prostate tissues.

• Journal of radiological science and technology
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• v.6 no.1
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• pp.3-19
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• 1983

• Journal of Biomedical Engineering Research
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• v.3 no.2
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• pp.119-122
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• 1982

This paper presents the principles of image formation in NMR(Nuclear Magnetic Resonance) tomography. NMR tomographic imaging is a newly emerging, noninvasive, three-dimensional imaging technique. This new technique is an interdisciplinary science which encompasses the latest technologies in electrical, electronics, computers, physics, chemistry, mathematics, and medical sciences.

• Journal of the Korean Magnetic Resonance Society
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• v.20 no.1
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• pp.17-21
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• 2016

Periostin, a component of extracellular matrix (ECM) protein, is produced and secreted by the fibroblasts that are involved in chronic allergic inflammation diseases and various types of human cancers. Periostin protein is composed of multiple domains including four FAS1 domains which play important roles in cell adhesion and tumor metastasis by interacting with integrins. In spite of their important biological role, the structural information of periosin FAS1 domains was not revealed yet. Recently we systemically prepared various constructs of the FAS1 domains and tried to express them in E. coli. Of them, only single FAS1-II and -IV domains were highly soluble. Circular dichroism (CD) and nuclear magnetic resonance (NMR) studies revealed that the FAS1-IV domain might be suitable for three-dimensional structure determination using NMR spectroscopy.

• Journal of the Korean Magnetic Resonance Society
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• v.6 no.1
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• pp.38-44
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• 2002

60% Pt on Vulcan XC-72 with similar Pt sizes to fuel cell grade Pt black was investigated by $\^$13/C nuclear magnetic resonance spectroscopy (NMR), cyclic voltammery (CV), transmission electron microscopy (TEM). Experiments were carried out on electrochemically cleaned samples as well as as-received. The TEM and CV results showed that the average particle sizes were changed by cleaning. However, the chemical shift （$\delta$$\_$G/） of $\^$13/C of $\^$13/CO absorbed on Pt surfaces did not show any appreciable variation with particle size change as did in Pt black. These results indicate that a combination of different analytic techniques is essential to understand the properties of the metal particle catalysts and that the presence of carbon black support strongly influences the NMR data, probably through metal-support interaction.

• Journal of the Korean Magnetic Resonance Society
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• v.9 no.1
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• pp.21-28
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• 2005

$^{11}B$ nuclear magnetic resonance (NMR) measurements have been performed to investigate electronic structures and vortex states of $M_gB_2$ superconductor. The central transition shows a narrow peak down to 25 K at 3.15 T. Below 25 K, an extra line starts to show up and dominates. The extra line is broad and asymmetric with a long tail in the high frequency side, which confirms that this originates from vortex pinning below the irreversibility temperature. From temperature evolution of the fraction and linewidth of the broad portion, temperature dependence of coherence length and penetration depth are extracted.