• 한국초전도학회:학술대회논문집
• /
• v.10
• /
• pp.61-64
• /
• 2000

$^{11}$B NMR measurements have been performed to investigate local electronic structure and 4f spin dynamics for TbNi$_2$B$_2$C single crystal. $^{11}$B NMR spectra show three resonance peaks due to the quadrupolar interaction. Shift and linewidth are huge and strongly temperature-dependent. In addition, both are proportional to magnetic susceptibility, indicating that the hyperfine field at the boron site originates from the 4f spins of Tb. $^{11}$B NMR shift and relaxation rates show high anisotropy for field parallel and perpendicular to the c-axis. Anisotropy of the shift and the relaxation rates suggests that the hyperfine field perpendicular to the c-axis is larger.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2002.08a
• /
• pp.635-638
• /
• 2002

In $ABCO_4$ and $ABC_3O_7$ (A=Ca, Sr; B=Y, Rare earth; C=Al, Ga), random distribution of static crystalline fields in activator sites results in inhomogeneous broadening of spectral lines of luminescent materials. In this study, we investigated luminescent properties of above-mentioned materials by excitation and emission spectra. In result, both $ABCO_4$:Tb and $ABC_3O_7$:Tb phosphors emit the green light. $ABC_3O_7$:Tb phosphors absorbed shorter wavelength energy than $ABCO_4$ phosphors so that the emission efficiencies of $ABC_3O_7$:Tb phosphors were higher than those of $ABCO_4$:Tb phosphors under vacuum UV.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08b
• /
• pp.1352-1355
• /
• 2007

An new green phosphor, $(Y,Gd)Al_3(BO_3)_4$:Tb was synthesized by flux assisted solid reaction and its VUV excitation and emission characteristics were examined. The luminance of $(Y,Gd)Al_3(BO_3)_4$:Tb at 147 nm excitation was higher than that of $YBO_3:Tb$, while keeping the spectra and decay time of Tb ion same as those of $YBO_3:Tb$.

• Journal of the Korean Magnetic Resonance Society
• /
• v.10 no.2
• /
• pp.197-202
• /
• 2006

[ $^{11}B$ ] nuclear magnetic resonance (NMR) measurements were performed on the single crystals of $TbB_4$ to investigate local electronic structure and 4f spin dynamics. $^{11}B$ NMR spectrum, Knight shift, spin-lattice and spin-spin relaxation rates were measured down to 4K at 8T. $^{11}B$ NMR shift and linewidth are huge and strongly temperature dependent due to the 4f moments. In addition, both are proportional to magnetic susceptibility, indicating that the hyperfine field at the boron site originates from the 4f spins of Tb. Below $T_N$, the single broad resonance peak of $^{11}B$ NMR splits into several peaks reflecting the local magnetic fields due to antiferromagnetic spin arrangements. The longitudinal and the transverse relaxation rates, $1/T_1\;and\;1/T_2$, independent of temperature above $T_N$, decreases tremendously confirming huge suppression of spin fluctuation below $T_N$.

• Molecules and Cells
• /
• v.37 no.4
• /
• pp.330-336
• /
• 2014

Thymosin beta4 (TB4) has multiple functions in cellular response in processes as diverse as embryonic organ development and the pathogeneses of disease, especially those associated with cardiac coronary vessels. However, the specific roles played by TB4 during heart valve development in vertebrates are largely unknown. Here, we identified a novel function of TB4 in endothelial-mesenchymal transformation (EMT) in cardiac valve endocardial cushions in zebrafish. The expressions of thymosin family members in developing zebrafish embryos were determined by whole mount in situ hybridization. Of the thymosin family members only zTB4 was expressed in the developing heart region. Cardiac valve development at 48 h post fertilization was defected in zebrafish TB4 (zTB4) morpholino-injected embryos (morphants). In zTB4 morphants, abnormal linear heart tube development was observed. The expressions of bone morphogenetic protein (BMP) 4, notch1b, and hyaluronic acid synthase (HAS) 2 genes were also markedly reduced in atrio-ventricular canal (AVC). Endocardial cells in the AVC region were stained with anti-Zn5 antibody reactive against Dm-grasp (an EMT marker) to observe EMT in developing cardiac valves in zTB4 morphants. EMT marker expression in valve endothelial cells was confirmed after transfection with TB4 siRNA in the presence of transforming growth factor ${\beta}$ ($TGF{\beta}$) by RT-PCR and immunofluorescent assay. Zn5-positive endocardial AVC cells were not observed in zTB4 morphants, and knockdown of TB4 suppressed TGF-${\beta}$-induced EMT in ovine valve endothelial cells. Taken together, our results demonstrate that TB4 plays a pivotal role in cardiac valve formation by increasing EMT.

• Transactions on Electrical and Electronic Materials
• /
• v.13 no.5
• /
• pp.262-265
• /
• 2012

The Microstructure and nonlinear electrical properties of the ZPCCYT (ZnO-$Pr_6O_{11}$-CoO-$Cr_2O_3$-$Y_2O_3$-$Tb_4O_7$) varistors were investigated for different amounts of $Tb_4O_7$. The addition of $Tb_4O_7$ has a significant effect on microstructure and electrical properties. Analysis of the microstructure indicated that the ceramics consisted of ZnO grain as a main phase and a few secondary phases as a mix of $Pr_6O_{11}$, $Y_2O_3$, and $Tb_4O_7$. As the amount of $Tb_4O_7$ increased, the sintered densities of pellets increased from $\rho$ = 5.70 to $5.78g/cm^3$ and the average grain size decreased from d = 4.8 to $3.6{\mu}m$. The increase in the amount of $Tb_4O_7$ increased from $E_B$ = 7,473 to 10,035 V/cm and from ${\alpha}$ = 39.7 to 52.2. In particular, it was found that the ceramics modified with 1.0 mol% in the amount of $Tb_4O_7$ are suited for the varistors for high voltage in the light of a high sintered density and a high voltage gradient.

• Korean Journal of Materials Research
• /
• v.10 no.1
• /
• pp.49-54
• /
• 2000

The new green $Al_3GdB_4O_{12}:Tb^{3+} and red Al_3GdB_4O_{12}:Eu_{3+}$ phosphors were synthesized and then characterized their optical properties for PDP application. And also the photoluminescence properties of these phosphors were compared with the commercial green $Zn_2SiO_4:Mn^{2+} and (Y,Gd)BO_3: Eu^{3+}$ red PDP phosphors. The phosphors were synthesized by solid state reaction at 115$0^{\circ}C$ for 4hr. It was found that the emitting brightness of $Al_3GdB_4O_{12}:Tb^{3+}$(15mol%) green phosphor under 147nm excitation was higher than that of commercial $Zn_2SiO_4: Mn^{2+}$ green PDP phosphor. However, the color coordinate of this new green phosphor was inferior to the commercial one. On the other hand, the emitting intensity of $Al_3GdB_4O_{12}:Eu^{3+}$(15mol%) red phosphor was smaller than the $commercial(Y,Gd)BO_3: Eu^{3+}$ red one, but the CIE coordinate was slightly improved. The excitation spectrum showed that $Al_3GdB_4O_{12}$ phosphors had a strong excitation band at $\lambda=160nm$ associated with the host absorption. And the photoluminance excitation (PLE) intensity in VUV range for $Al_3GdB_4O_{12}:Tb^{3+}$ green phosphor was higher than that of $Zn_2SiO_4: Mn^{2+}$, but the PLE intensity of $Al_3GdB_4O_{12}:Eu^{3+}$ red phosphor was smaller than $(Y,Gd)BO_3: Eu^{3+}$.

• Journal of agricultural medicine and community health
• /
• v.18 no.2
• /
• pp.141-151
• /
• 1993

This study was done about 371 tuberculosis(TB) patients composed 195 newly registered at Kyungju Gun Health Center from May 1989 to April 1990 (Group A) and 176 being treated at hospitals or private clinics from January 1988 to November 1989(Group B). When Group A patients visited and newly registered at Health Center, data was obtained by interviewing with a prepared questionnaire paper. And well trained inquirer visited Group B patients and obtained data by the same method from February 1990 to April 1990. The results are as follows ; Group A was generally lower than Group B in socioeconomic status and in family history of TB, the rate of Group A was 24.1% and higher than 11.9% in Group B(p<0.05). Knowledge about TB was improved more than past, but those who answered that TB is 'a communicable disease' were 59.5% in Group A and 51.7% in Group B(p<0.05). Those answered that TB is 'a inherited disease' were 9.2% and 11.4% each. And 1.7% of Group B answered that TB is 'a incurable disease'. Knowledge about TB treatment also was improved more than past, but in the rate of those who answered that TB is a curable disease provided by well treatment Group B(77.8%) was worse than Group A(91.3%). The rate of those who answered that TB were been able to cure by regularly anti-TB medication were 98.0% in Group A and 89.8% in Group B. Its difference was statistically significant. The rate that patients took the first diagnosis and wanted to receive treatments at the same organ were 34.9% of Group A at Health Center and 72.2% of Group B at hospitals or private clinics. And its difference was statistically significant. In the reasons that Group B knew Health Center treated pulmonary TB but they was treated at hospitals or private clinics, unreliability to Health Center was 48.1%. The reasons that Group A was treated at Health Center were 'because of trust' 63.1%, 'because of low cost' 50.3%, 'because of low cost except trust' 9.3%, 'no specific reasons' 27.7%. In the courses of knowing that TB was controlled at Health Center, 'by neighborhood, health worker and doctors' were 84.9% in Group A and 69.0% in Group B. But 'by TV or radio' were 8.2% in Group A and 14.7% in Group B, 'by school education' 2.5% in Group A and 6.2% in Group B. Conclusively, Group A patients were lower than Group B in socioeconomic status, but better than in knowledge about TB. Its reasons was suggested that Health Center had controlled TB patients better than hospitals and private clinics. But considering, that difference in the rate of the same organ for the first diagnosis and treatment, that the only 63.0% of Group A have treated due to 'reliability to Health Center', and that 48.1% of Group B knew that Health Center treated pulmonary TB but didn't visit it due to 'unreliability to Health Center', that public relations(PR) about use Health Center for pulmonary TB and health education for TB was thought to have to strengthened.

• 한국초전도학회:학술대회논문집
• /
• v.9
• /
• pp.206-209
• /
• 1999

Magnetic and superconducting properties in a series of intermetallic compounds Y$_{1-x}Tb_xNi_2B_2C$ were investigated by measuring the temperature dependent magnetization, M (T), and resitivity, ${\rho}$ (T). As Tb concentration, x, is increased, the superconducting transition temperature, T$_c$, decreases and eventually disappears in the vicinity of x = 0.5 while Neel temperature, T$_N$, appears abruptly near x = 0.4 and increases linearly. Of particular interest is the collision of superconductivity and antiferromagnetism around x = 0.4. The linear decrease of T$_c$ for dilute Tb concentration seems to follow the Abrikosov-Gor'kov behavior, while the decay of T$_c$ below T$_c$ is expected to originate from the effective magnetic field on the conduction electrons. The Ginzburg-Landau theory was phenomenologically constructed to explain this competition of superconducting order parameter and antiferromagnetic order parameter with the multi-band model.

• Current Applied Physics
• /
• v.18 no.11
• /
• pp.1205-1211
• /
• 2018

The frustrated magnet has been regarded as a system that could be a promising host material for the quantum spin liquid (QSL). However, it is difficult to determine the spin configuration and the corresponding mechanism in this system, because of its geometrical frustration (i.e., crystal structure and symmetry). Herein, we systematically investigate one of the geometrically frustrated magnets, the $TbB_4$ compound. Using resonant soft x-ray scattering (RSXS), we explored its spin configuration, as well as Tb's quadrupole. Comprehensive evaluations of the temperature and photon energy/polarization dependences of the RSXS signals reveal the mechanism of spin reorientation upon cooling down, which is the sophisticated interplay between the Tb spin and the crystal symmetry rather than its orbit (quadrupole). Our results and their implications would further shed a light on the search for possible realization of QSL.