• Journal of Magnetics
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• 제6권4호
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• pp.142-144
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• 2001

A method to deduce the rotational magnetization curve from experimental magnetization of partially aligned uniaxial anisotropy system has been investigated. The curve obtained by this process has been evaluated quire close to the theoretical magnetization curve compared to that obtained by linear extrapolation from high field data. This new approach offers better accuracy for the determination of magnetic anisotropy by fitting a calculated magnetization curve to the obversed one.

• 한국전기전자재료학회논문지
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• 제11권6호
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• pp.486-492
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• 1998

The amorphous Co-based magnetic films have a large saturation flux density, a low coercive force, and a zero magnetostriction constant. Therefore, they have been studied for application to magnetic recoding heads and micro magnetic devices. However, it was found that the magnetic anisotropy was changed for each film fabrication processes. In this study, we investigated how to control the anisotropy of sputtered amorphous $Co_{89}Nb{8.5}Zr{2.5}$ films. After deposition, the rotational field annealing ant the uniaxial field annealing were performed under the magnetic field of 1.5 kOe. the annealing was done at the temperature range from 400 to $600^{\circ}C$ for one hour. As-deposited amorphous $Co_{89}Nb{8.5}Zr{2.5}$ thin film had saturation magnetization ($4\piM_5$) of 0.8 T, coercive force($_IH_C$) of 1.5 Oe, and anisotropy field($H_k$) of 11 Oe. The amorphous $Co_{89}Nb{8.5}Zr{2.5}$ thin films annealed by rotational field annealing at $500^{\circ}C$ for one hour was found to be isotropy, and $4\piM_5$ of 0.9 T was obtained from these films, Also, the magnetic anisotropy of as-deposited films could be controlled by uniaxial field annealing at $400^{\circ}C$ for one hour. Anisotropy field($H_k$) of 17 Oe and $4\piM_5$ of 1.0 T were obtained by this method.

• Journal of Photoscience
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• 제11권1호
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• pp.35-40
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• 2004

[Ru(2,2'-bipyridine)$_2$(4,4'-dicarboxy-2,2'-bipyridine)]$^{2+}$(RuBDc) is a very photostable probe that possesses favorable photophysical properties including long lifetime, high quantum yield, large Stokes' shift, and highly polarized emission. To evaluate the usefulness of this luminophore (RuBDc) for studying macromolecular dynamics, its intensity and anisotropy decays when conjugated to RNA bacteriophage MS2 were examined using frequency-domain fluorometry with a high-intensity, blue light-emitting diode (LED) as the modulated light source. The intensity decays were best fit by a sum of two exponentials, and the mean intensity decay time was 442.2 ns. The anisotropy decay data showed a single rotational correlation time (2334.9 ns), which is typical for a spherical molecule. The use of RuBDc enabled us to measure the rotational correlation time up to several microseconds. These results indicate that RuBDc can be useful for studying rotational diffusion of biological macromolecules.s.

• Journal of Photoscience
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• 제7권4호
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• pp.155-159
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• 2000

[Ru(bpy)$_2$(dppz)]$^2$$^{+}$ (bpy = 2,2'-bipyridine, dppz = dipyrido[3,2-a:2',3'-c]phenazine)(RuBD), a long-lifetime metal-ligand complex displays photophysical properties including long lifetime, polarized emission, and very little background fluorescence. To further show the usefulness of this luminophore(RuBD) for probing nucleic acid dynamics, its intensity and anisotropy decays when bound to tRN $A^{val}$ were examined using frequency-domain fluorometry with a blue light-emitting diode(LED)as the modulated light source. Unexpectedly much longer mean lifetime was obtained at 4$^{\circ}C$(<$\tau$>=178.3 ns) as compared to at $25^{\circ}C$(<$\tau$>=117.0 ns), suggesting more favorable conformation of tRN $A^{val}$ for RuBD when intercalated at 4$^{\circ}C$. The anisotropy decay data showed longer rotational correlation times at 4$^{\circ}C$(52.7 and 13.0 ns) than at $25^{\circ}C$ (32.9 and 10.3 ns). The presence of two rotational correlation times suggests that RuBD reveals both local and overall rotational motion of tRN $A^{val}$. Due to long lifetime of RuBD and small size of tRN $A^{val}$, very low steady-state anisotropy values were observed, 0.048 and 0.036 at 4 and $25^{\circ}C$, respectively. However, a clear difference in the modulated anisotropy values was seen between 4 and $25^{\circ}C$. These results indicate that RuBD can be useful for studying hydrodynamics of small nucleic acids such as tRN $A^{val}$.^{val}$.>.$.>.

• BMB Reports
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• 제33권6호
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• pp.541-547
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• 2000

Fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) was used to evaluate the effects of chlorpromazine HCl on the range of the rotational mobility of bulk bilayer structure of the synaptosomal plasma membrane vesicles (SPMV) isolated from a bovine brain. In a dose-dependent manner, chlorpromazine HCl increased the anisotropy (r), limiting anisotropy ($r_{\infty}$) and order parameter (S) of DPH in the membranes. Cationic 1-[4-(trimethylammonio)-phenyl]-6-phenylhexa-1,3,5-hexatriene (TMA-DPH) and anionic 3-[p-(6-phenyl)-1,3,5-hexatrienyl]-phenylpropionic acid (PRO-DPH) were utilized to examine the range of transbilayer asymmetric rotational mobility of the neuronal membranes. The anisotropy (r) of TMA-DPH in the inner monolayer was 0.034 greater than the value of PRO-DPH in the outer monolayer of the membranes. Both cationic TMA-DPH and anionic PRO-DPH were also used to examine the transbilayer asymmetric effects of chlorpromazine HCl on the range of rotational mobility of the membranes. Chlorpromazine HCl have a decreasing effects on the rotational mobility of the bulk bilayer structures and have a greater decreasing effect on the mobility of the inner monolayer as compared to the outer monolayer of the membranes. It has been proven that chlorpromazine HCl exhibit a selective rather than nonselective fluidizing effect within the transbilayer domains of the SPMV.

• BMB Reports
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• 제33권3호
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• pp.279-284
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• 2000

Using fluorescence probes, 2-(9-anthroyloxy) stearic acid (2- AS) and 12-(9-anthroyloxy) stearic acid (12-AS), we determined the differential effects of local anesthetics (tetracaine-HCI, bupivacaine-HCI, lidocaine-HCI, prilocaine-HCI and procaine-HCI) on the differential rotational rate between the surface (in carbon number 2 and its surroundings including the head group) and the hydrocarbon interior (in carbon number 12 and its surroundings) of the outer monolayer of the total phospholipid fraction liposome that is extracted from synaptosomal plasma membrane vesicles. The anisotropy (r) values for the hydrocarbon interior and the surface region of the liposome outer monolayer were$0.051{\pm}0.001$ and $0.096{\pm}0.001,$ respectively. This means that the rate of rotational mobility in the hydrocarbon interior is faster than that of the surface region. Local anesthetics in a dosedependent manner decreased the anisotropy of 12-AS in the hydrocarbon interior of the liposome outer monolayer, but increased the anisotropy of 2-AS in the surface region of the monolayer. These results indicate that local anesthetics have significant disordering effects on the hydrocarbon interior, but have significant ordering effects on the surface region of the liposome outer monolayer.

• The Korean Journal of Physiology and Pharmacology
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• 제4권1호
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• pp.41-46
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• 2000

Using fluorescence polarization of 12-(9-anthroyloxy)stearic acid (12-AS) and 2-(9-anthroyloxy)stearic acid (2-AS), we evaluated the differential effects of local anesthetics on differential rotational rate between the surface (in carbon number 2 and its surroundings including the head group) and the hydrocarbon interior (in carbon number 12 and its surroundings) of the outer monolayer of the total lipid fraction liposome extracted from synaptosomal plasma membrane vesicles. The anisotropy (r) values for the hydrocarbon interior and the surface region of the liposome outer monolayer were $0.078{\pm}0.001$ and $0.114{\pm}0.001,$ respectively. This means that the rate of rotational mobility in the hydrocarbon interior is faster than that of the surface region. In a dose-dependent manner, the local anesthetics decreased the anisotropy of 12-AS in the hydrocarbon interior of the liposome outer monolayer but increased the anisotropy of 2-AS in the surface region of the monolayer. These results indicate that local anesthetics have significant disordering effects on the hydrocarbon interior but have significant ordering effects on the surface region of the liposome outer monolayer.

• Journal of Magnetics
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• 제3권4호
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• pp.123-126
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• 1998

The magneto-impedance (MI) has been measured in the annealed Co66Fe4Ni1B14Si15 amorphous ribbon for the evaluation of anisotropy field. MI at the frequency of 10 MHz is related to the transverse permeability from rotational magnetization depending on the local anisotropy field. MI varies sensitively with the annealing temperature, reflecting the change of anisotropy field distribution. The local anisotropy fields evaluated from MI Profiles are discussed in terms of the magnetic softness and microstructural change by the annealing.

• Bulletin of the Korean Chemical Society
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• 제4권1호
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• pp.48-54
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• 1983

A magnetic nucleus located on an internal rotor can interact with magnetic fields arising from end-over-end molecular rotation as well as internal rotation. In this paper the expressions for spin-rotational relaxation times, $T_{1.SR}\;and\;T_{2.SR}$, are derived for such nucleus with the anisotropy of molecular rotation explicitly taken into consideration. The derived expressions are shown to be composed of two parts, the contribution from spin-overall-rotation coupling and that from spin-internal-rotation coupling. Some remarks on the use of derived expressions are also provided.

• 한국자기학회지
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• 제24권5호
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• pp.140-145
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• 2014

본 연구에서는 교환 결합 특성을 갖는 CoFe/MnIr 박막 재료에서 MnIr의 두께에 따라 측정한 토오크 신호를 Stoner-Wohlfarth 모델로 계산한 결과와 비교 분석하였다. 모델 계산을 위하여 일축 이방성 상수 $K_F$와 $K_{AF}$를 각각 갖는 강자성(F)층과 반강자성 (AF)층 계면에 작용하는 교환 결합 상수 $J_c$를 고려하였다. 고정되지 않는 AF층에 의한 회전 손실은 $0.5t_c$ < $t_{AF}$ < $t_c$ ($=J_c/K_{AF}$)의 범위에서 나타나며, 고정된 AF층에 의한 일방 이방성 상수 $J_k$는 $t_{AF}$ > $t_c$에서 나타났다. CoFe/MnIr 재료에서 임계두께는 $t_c$ = 3.4 nm였으며, $t_{AF}$ = 3 nm의 시편에서 측정한 토오크 신호에서 보인 회전 손실은 AF 결정립의 용이축이 모든 방향으로 고르게 분포한 특성으로 설명되었다. $t_{AF}$ = 10 nm의 시편에서 측정된 토오크 신호에서 추출한 일방 이방성 상수는 $J_k=0.63J_c$의 관계를 보였다. 따라서, 일방 이방성 상수는 AF 결정립의 용이축을 한쪽 방향으로 정렬할 경우 $J_k=J_c$가 되어 약 37 %의 특성 향상을 기대할 수 있다.