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생활치 표백술 후 수종의 자유 산소기 제거제 처리가 복합 레진-법랑질 전단 접착 강도 및 파절 양상에 미치는 영향
임경한,금기연,김애리,장수미 대한치과보존학회 2001 Restorative Dentistry & Endodontics Vol.26 No.5
Tooth bleaching has been prevailing recently for its ability to recover the color and shape of natural teeth without reduction of tooth material. However, it has been reported that bleaching procedure adversely affects the adhesive bond strength of composite resin to tooth. At the same time the bond strength was reported to be regained by application of some chemical agents. The purpose of this in vitro study was to investigate the effect of the removal of residual peroxide on the composite- enamel adhesion and also evaluated fracture mode between resin and enamel after bleaching. Sixty extracted human anterior and premolar teeth were divided into 5 groups and bleached by combined technique using office bleaching with 35 % hydrogen peroxide and matrix bleaching with 10% carbamide peroxide for 4 weeks. After bleaching, the labial surfaces of each tooth were treated with catalase, 70% ethyl alcohol, distilled water and filled with composite resin. Shear bond strength was tested and the fractured surfaces were also examined with SEM. Analysis revealed significantly higher bond strength values. (p<0.05) for catalase-treated specimens, but water-treated specimens showed reduction of bond strength, alcohol- treated specimens had medium value between the two groups(p<0.05). The fracture mode was shown that the catalase group and the alchohol group had cohesive failure but the water sprayed group had adhesive failure. It was concluded that the per-oxide residues in tooth after bleaching seems to be removed by gradual diffusion and the free radical oxygen from peroxide prevents polymerization by combining catalyst in the resin monomer. Therefore it may be possible to eliminate the adverse effect on the adhesion of composite resin to enamel after bleaching by using water displacement solution or dentin bonding agent including it for effective removal of residual per-oxide Key words : Vital tooth bleaching, Shear bond strength, Composite resin, Fracture mode catalase, Ethylalcohol, Free oxygen radical, Adhesive failure, Cohesive failure
Lim, Ae Ran,Lee, Kwang-Sei Korean Magnetic Resonance Society 2015 Journal of the Korean Magnetic Resonance Society Vol.19 No.1
The microscopic dynamics of $CsH_2PO_4$, with two distinct hydrogen bond lengths, are studied by static nuclear magnetic resonance (NMR) and magic angle spinning (MAS) NMR. The proton dynamics of the two crystallographically inequivalent hydrogen sites were discussed in terms of the $^1H$ NMR and $^1H$ MAS NMR spectra. Although the hydrogen bonds have two inequivalent sites, H(1) and H(2), distinct proton dynamics for the two sites were not found. Further, the $^{133}Cs$ spectrum is more or less continuous near $T_{C1}$ (=153 K). Finally, the phase transition mechanism of $T_{C1}$ in $CsH_2PO_4$ is related to the ordering of protons.
Lim, Ae Ran,Lee, Ju Ha WILEY-VCH Verlag 2010 Physica Status Solidi. B Vol.247 No.5
<P>The NMR spectrum, spin–lattice relaxation times, T<SUB>1</SUB>, and the spin–spin relaxation times, T<SUB>2</SUB>, for the <SUP>23</SUP>Na and <SUP>87</SUP>Rb nuclei in Tutton salts Na<SUB>2</SUB>Zn(SO<SUB>4</SUB>)<SUB>2</SUB>·6H<SUB>2</SUB>O and Rb<SUB>2</SUB>Zn(SO<SUB>4</SUB>)<SUB>2</SUB>·6H<SUB>2</SUB>O single crystals were determined by using an FT NMR spectrometer. The NMR spectrum and relaxation times for the <SUP>23</SUP>Na and <SUP>87</SUP>Rb nuclei in two crystals undergo significant changes near T<SUB>C</SUB>. These changes close to T<SUB>C</SUB> were the only detectable result of the structural transformation; the change is due to the fact that the electric field gradient value becomes 0. Especially, T<SUB>1</SUB> and T<SUB>2</SUB> for <SUP>87</SUP>Rb in the Rb<SUB>2</SUB>Zn(SO<SUB>4</SUB>)<SUB>2</SUB>·6H<SUB>2</SUB>O crystals at high temperature have similar values on the order of milliseconds, which is indicative of a liquid-like system. The motion giving rise to this liquid-like behavior is probably related to superionic motion at high temperature.</P>
Lim, Ae Ran Korean Magnetic Resonance Society 2017 Journal of the Korean Magnetic Resonance Society Vol.21 No.2
The $^{14}N$ NMR spectra for $(NH_4)_2SO_4$ crystals were obtained near the phase transition temperature $T_C=223K$, and were found to precisely reflect the symmetry change in the crystal at this first-order phase transition. Changes in the resonance frequencies near $T_C$ were attributed to the structural phase transition. In the ferroelectric and paraelectric phases, two inequivalent NH4 groups were distinguished in the $^{14}N$ NMR spectra. The two types, $NH_4$(1) and $NH_4$(2), have slightly different local environments. Consequently, we conclude that the phase transition is caused by the change in the environment of the $^{14}N$ nuclei in the $NH_4$ groups, rather than by the $SO_4$ groups.
Lim, Ae Ran,Jeong, Se-Young IOP Pub 2006 Journal of Physics, Condensed Matter Vol.18 No.29
<P><I>T</I><SUB>1</SUB>, <I>T</I><SUB>1ρ</SUB> and <I>T</I><SUB>2</SUB> for the <SUP>1</SUP>H and <SUP>2</SUP>H nuclei in (NH<SUB>4</SUB>)<SUB>3</SUB>H(SO<SUB>4</SUB>)<SUB>2</SUB> and (ND<SUB>4</SUB>)<SUB>3</SUB>D(SO<SUB>4</SUB>)<SUB>2</SUB> single crystals grown using the slow evaporation method were measured for phases I, II, III, IV and V. The <SUP>1</SUP>H <I>T</I><SUB>1</SUB>, <I>T</I><SUB>1ρ</SUB>, and <I>T</I><SUB>2</SUB> values were found to exhibit different trends in phases II and III: <I>T</I><SUB>1</SUB>, <I>T</I><SUB>1ρ</SUB> and <I>T</I><SUB>2</SUB> for <SUP>1</SUP>H do not change significantly near the phase transition at 265 K, whereas near 413 K they change discontinuously. We conclude that the NH<SUB>4</SUB><SUP>+</SUP> and H(SO<SUB>4</SUB>)<SUB>2</SUB><SUP>−</SUP> ions do not play an important role in the III–II phase transition, but do play important roles in the II–I phase transition. The liquid-like nature of the <SUP>1</SUP>H <I>T</I><SUB>1ρ</SUB> and <I>T</I><SUB>2</SUB> above 413 K is indicative of the destruction and reconstruction of hydrogen bonds. Moreover, the phase transitions of the (NH<SUB>4</SUB>)<SUB>3</SUB>H(SO<SUB>4</SUB>)<SUB>2</SUB> crystal are accompanied by changes in the molecular motion of the (NH<SUB>4</SUB>)<SUP>+</SUP> ions. The variations with temperature of the <SUP>2</SUP>H <I>T</I><SUB>1</SUB> and <I>T</I><SUB>2</SUB> of (ND<SUB>4</SUB>)<SUB>3</SUB>D(SO<SUB>4</SUB>)<SUB>2</SUB> crystals are not similar to those observed for the <SUP>1</SUP>H <I>T</I><SUB>1</SUB> and <I>T</I><SUB>2</SUB>. Our comparison of the results for (NH<SUB>4</SUB>)<SUB>3</SUB>H(SO<SUB>4</SUB>)<SUB>2</SUB> and (ND<SUB>4</SUB>)<SUB>3</SUB>D(SO<SUB>4</SUB>)<SUB>2</SUB> crystals indicates the following: the <SUP>1</SUP>H <I>T</I><SUB>1ρ</SUB> and <I>T</I><SUB>2</SUB> of the (NH<SUB>4</SUB>)<SUP>+</SUP> and H(SO<SUB>4</SUB>)<SUB>2</SUB><SUP>−</SUP> ions above <I>T</I><SUB>C1</SUB> are characteristic of fast, liquid-like motion, which is not the case for (ND<SUB>4</SUB>)<SUB>3</SUB>D(SO<SUB>4</SUB>)<SUB>2</SUB>; and the <SUP>2</SUP>H <I>T</I><SUB>1</SUB> of D(SO<SUB>4</SUB>)<SUB>2</SUB><SUP>−</SUP> in (ND<SUB>4</SUB>)<SUB>3</SUB>D(SO<SUB>4</SUB>)<SUB>2</SUB> is longer than the <SUP>2</SUP>H <I>T</I><SUB>1</SUB> of (ND<SUB>4</SUB>)<SUP>+</SUP> in contrast to the results for (NH<SUB>4</SUB>)<SUB>3</SUB>H(SO<SUB>4</SUB>)<SUB>2</SUB> crystals.</P>
A Study on Ferroelastic Distortion in BiVO₄
Lim, Ae-Ran,Chang, Jin-Hae 金烏工科大學校 1988 論文集 Vol.9 No.-
The structural distortions in ferroelastic based on bond-length/bond-strength relationships is analysised. The calculated bon-strength and observed asymmetry parameter of 51V NMR in BiVO₄ as a function of temperature was compared with symmetry around vanadium. The based on these results, the structural mechanism of the phase transition in BiVO₄ is presented. The Bi-O polyhedron is regular above the ?? but becomes significantly distorted below the ??. The phase transition in BiVO₄ seems to be the lone-electron pair which plays a prominent role in the Bi3+ion.