• The Journal of the Acoustical Society of Korea
• /
• 제25권1E호
• /
• pp.14-19
• /
• 2006

Ultrasonic absorption and velocity spectra in bovine serum albumin (BSA) aqueous solutions have been measured at $20^{\circ}C$ over the frequency range 0.2-3 MHz in the pH range 1.5-13.2. The high-Q ultrasonic resonator and pulse-echo overlap methods were used. At acid pH's, excess absorption over that of pH 7 was explained by double relaxation. The pH dependences of the relaxation frequency and maximum absorption per wavelength, showed that the relaxation at about 200 kHz was related to the expansion of molecules and that about 3 MHz resulted from the proton transfer reaction of carboxyl group. At alkaline pH's, the excess absorption was explained by double relaxation. The relaxation at about 300 kHz was associated with a helix-coil transition, and that about 3 MHz was attributed to the proton transfer reaction of phenolic group. The rate constants and volume changes associated with these processes were estimated.

• 한국자기학회지
• /
• 제5권5호
• /
• pp.854-857
• /
• 1995

비자성 분순물을 갖는 $CuF_{2}.2H_{2}O$의 수소 핵자기공명을 77-295 K의 온도범위에서 수행하였다. 그 결과 수소의 스핀-격자 완화율을 지배하는 메카니즘이 구리 전자 스핀의 재주넘기(filp)와 전자-포논 상호작용(Raman process)의 변조에 의한 것임을 알 수 있었다. 또한 전자 스핀 재주넘기에 대한 교환에너지 $1.8(\pm0.04)$ K를 구할 수 있었다.

• 농업과학연구
• /
• 제32권1호
• /
• pp.63-70
• /
• 2005

야관문에서 추출한 n-hexane층을 음경해면체 평활근의 활성물질 탐색한 결과 극성 별로 분리한 9개 모든 시료에서 정도의 차이는 있으나 음경해면체 평활근의 이완 반응을 일으켰으며, 추출물 $10{\mu}l$ 투여한 9개 시료 중 A시료($20.2{\pm}6.0%$) 가 최고의 이완 반응을 보였으며, $15{\mu}l$를 투여한 시료 중에서는 J시료($54.8{\pm}9.7%$)가 최고의 이완 반응이 나타났다. 한편 야관문 추출물의 농도를 제일 많은량 $20{\mu}l$를 투여한 시료들 중에서는 H시료와 J시료가 95% 이상의 높은 이완 반응을 보였다. 시료중 최고 활성을 나타난 시료 H를 prep-HPLC 및 분석용 HPLC를 이용, YK-H1, YK-H2, YK-H3 및 YK-H4등 4개의 물질을 분리하였으며, 또한 시료 J를 prep-HPLC 및 분석용 HPLC를 이용하여 YK-J1, YK-J3 및 YK-J4등 세 개의 물질을 분리하였다. 분리된 7개의 물질들의 구조 결정에 대한 연구를 진행하고 있다.

• Journal of Magnetics
• /
• 제1권1호
• /
• pp.37-41
• /
• 1996

The frequency dependence of complex permeability for various NiCuZn ferrites was investigated. The variation of complex permeability for NiCuZn ferrites can be presented as a form of a semi-circle, so called the Cole-Cole plot, and the relaxation phenomena were explained with various shapes of the plots. The relaxation time $\Upsilon$ was calculated from $f_rx$, which is a relaxation frequency at ${\mu"}_{max}$. Relations between anisotropy field $H_A$ and relaxation time $\Upsilon$, initial permeability $\mu_i$ and $H_A$ were plotted to identify the frequency dependence of complex permeability.lity.

• 한국자기공명학회논문지
• /
• 제20권1호
• /
• pp.1-6
• /
• 2016

The proton NMR line widths and spin-lattice relaxation rates, $T_1^{-1}$, of ferroelectric $LiH_3(SeO_3)_2$, $Li_2SO_4{\cdot}H_2O$, and $LiN_2H_5SO_4$ single crystals were measured as a function of temperature. The line width measurements reveal rigid lattice behavior of all the crystals at low temperatures and line narrowing due to molecular motion at higher temperatures. The temperature dependences of the proton $T_1^{-1}$ for these crystals exhibit maxima, which are attributed to the effects of molecular motion by the Bloembergen - Purcell - Pound theory. The activation energies for the molecular motions of $^1H$ in these crystals were obtained. From these analysis, $^1H$ in $LiH_3(SeO_3)_2$ undergoes molecular motion more easily than $^1H$ in $LiN_2H_5SO_4$ and $Li_2SO_4{\cdot}H_2O$ crystals.

• 한국자기공명학회논문지
• /
• 제14권1호
• /
• pp.18-27
• /
• 2010

The NMR spectrum and spin-lattice relaxation times, $T_1$, of the $^{1}H$ nuclei in $(NH_{4})_{2}Cd_{2}(SO_{4})_{3}$ single crystals were obtained. The two minima in $T_1$ in the paraelectric phase are attributed to the reorientational motions of the $NH_{4}^{+}$ groups. The $^{1}H\;T_1$ of the $(NH_{4})_{2}Cd_{2}(SO_{4})_{3}$ crystals can be described with Bloembergen- Purcell-Pound (BPP) theory. The experimental value of $T_1$ can be expressed in terms of an isotropic correlation time ${\tau}_H$ for molecular motions by using the BPP theory, and determine the role of protons in these processes.

• 한국자기학회지
• /
• 제5권1호
• /
• pp.54-57
• /
• 1995

넓은 범위의 $^{1}H$ 핵자기공명 자기장에서 Heisenberg 반강자성체인 $MnCl_{2}.4H_{2}O$에 대하여 상온 수소 핵자기완화를 연구하였다. $MnCl_{2}.4H_{2}O$는 상온에서 밀접한 상자성 $Mn^{++}$ 이온계이지만 희박한 상자성계에서 예상되는 특성을 보인 반면에 희박한 상자성 근사와 매우 다른 결과도 보였다. 또한 수소 원자핵들은 0.7 T의 외부자기장 부근에서 스핀-격자 완화시간의 이상거동을 보였다.

• 대한화학회지
• /
• 제36권1호
• /
• pp.33-37
• /
• 1992

티오아세트아미드/아세톤 용액에 대한 $^{14}N$ 이완속도를 $NH_2$기의 $^1H$ 공명 신호의 자세한 선모양분석으로부터 구하였다. 압력과 온도의 효과를 조사하고 분자 재배향의 활성화에너지를 구하였다. $NH_2$기의 $^1H$ 이온속도도 압력과 온도의 함수로 구하였다. 이들 결과를 아민기의 $^{14}N$ 이완의 결과와 함께 고찰하였다.

• 한국초전도ㆍ저온공학회논문지
• /
• 제25권3호
• /
• pp.28-33
• /
• 2023

Magnetic relaxation properties of pure MgB₂ powder samples and diluted water-treated MgB₂ powder samples were investigated. The magnetic field H-dependence, m(H), and the time t-dependence, m(t), of the magnetic moment m were measured and analyzed using the PPMS-VSM magnetometer equipment, respectively. The m(t) reduction rates of pure MgB₂ powder samples and diluted water-treated MgB₂ powder samples decreased to about 0.7 ~ 1.8% and 0.6 ~ 1.0% for about 7200 s, respectively, at temperature T = 15 K. The magnetic relaxation properties of the two types of MgB₂ powders were analyzed by calculating the magnetic relaxation rate S = -dln(M_irr)/dln(t) values according to Anderson-Kim theory. The magnetic relaxation ratio S values of the two types of MgB₂ powder samples were almost similar. As a result of the quantum creep effect, the constant magnetic relaxation rate S characteristic was confirmed at a temperature range of T = 10 K or less.

• 한국자기공명학회논문지
• /
• 제13권1호
• /
• pp.15-26
• /
• 2009

The NMR detection of methyl groups is of keen interest because they provide the long-range distance information required to establish global folds of high molecular weight proteins. Using longitudinal $^1H$ relaxation optimization, we achieve a gain in sensitivity of approximately 1.6-fold in the methyl-TROSY and its NOESY experiments for the 38 kDa protein mitogen activated protein kinase p38 in its fully protonated and $^{13}C$ and $^{15}N$ labeled state.