• Journal of the Korean Ceramic Society
• /
• v.39 no.11
• /
• pp.1074-1082
• /
• 2002

Nanocomposite PMN-PT-BT/Ag/MgO was prepared by sintering at $950{\circ}C$ with addition of $AgNO_3$ and MgO sol to the PMN-PT-BT powder sinterable at $1200{\circ}C$. The low-temperature-sinterable PMN-PT-BT/Ag powder prepared by the modified mixed oxide method was calcined at $600{\circ}C$ for 1h and surface modified with the MgO sol of 0-10 wt% and then subjected to consolidation at $850-950{\circ}C$ for 4h under a flowing oxygen. The nanocomposite PMN-PT-BT/Ag/MgO(0.5wt%) sintered at $950{\circ}C$ showed the microstructure with grains of $1-3{\mu}m$, the second phase of MgO of $0.1-0.3{\mu}m$ by SEM and Ag of << $1{\mu}m$ qualitatively by SIMS. It showed the sintered relative density of 99%, the room temperature dielectric constant of 17200, the dielectric loss of 2.1% and the specific resistivity of $5.46{\times}10^{12}{\Omega}{\cdot}cm$. But the PMN-PT-BT/Ag/MgO(0 wt%) nanocomposite sintered at $950{\circ}C$ showed a little better properties : the sintered relative density of 99.5%, the room temperature dielectric constant of 19500, the dielectric loss of 2.1% and the specific resistivity of $7.30{\times}10^{12}{\Omega}{\cdot}cm$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.03a
• /
• pp.18-20
• /
• 2010

The mechanism for suppression of Ag agglomeration in Ag-Mg alloy ohmic contact to p-GaN is investigated. The Ag-Mg alloy ohmic contact shows low contact resistivity of $6.3\;{\times}\;10^{-5}\;{\Omega}cm^2$, high reflectance of 85.5% at 460 nm wavelength after annealing at $400^{\circ}C$ and better thermal stability than Ag contact The formation of Ga vacancies increase the net hole concentration, lowering the contact resistivity. Moreover, the oxidation of Mg atoms in Ag film increase the work function of Ag-Mg alloy contact and prevents Ag oxidation. The inhibition of oxygen diffusion by Mg oxide suppresses the Ag agglomeration, leading to enhance light reflectance and thermal stability.

• Journal of the Korean Magnetics Society
• /
• v.21 no.6
• /
• pp.214-218
• /
• 2011

In this study, we have systematically investigated the effect of sputtering conditions on the microstructural properties of Ag/CoFeB thin film on MgO substrate. It was found that the crystallinity and surface roughness of the Ag film strongly depends on the Ar sputtering pressure and sputtering power. Epitaxial growth of Ag(100) film on MgO(100) substrate was achieved under the sputtering conditions of high sputtering power and elevated temperature. XRR (X-ray reflectivity) and high-resolution TEM (transmission electron microscopy) measurements also revealed the interfacial roughening in the Ag/CoFeB interface due to the island structure formation and intermixing between Ag and CoFeB.

• Journal of Plant Biotechnology
• /
• v.50
• /
• pp.169-175
• /
• 2023

A plant regeneration system was developed through shoot organogenesis from in vitro leaf explants of Chrysanthemum morifolium 'Ohblang'. The effects of different concentrations of plant growth regulators and AgNO₃ on efficient shoot regeneration and inhibition of browning were evaluated in chrysanthemum. The explants were cultured on MS shoot induction medium supplemented with 12 combination treatments of 6-benzyladenine (BA) 0.5, 1.0 and 2.0 mg/L, and α-naphthaleneacetic acid (NAA) 0.2, 0.5, 1.0 and 2.0 mg/L in darkness for 6 weeks and cultured under a 16/8 h photoperiod for 6 weeks. The highest shoot regeneration was obtained from the explants cultured on the medium with 1.0 mg/L BA and 1.0 mg/L NAA. Based on this result, AgNO₃ was added to a shoot induction medium containing MS salts, vitamins, 1.0 mg/L BA, 1.0 mg/L NAA, 30 g/L sucrose, and 6 g/L agar to reduce browning of chrysanthemum leaf explants. In the control treatment without AgNO₃, leaf explants turned brown at the cut edge; however, browning was not observed in AgNO₃ treatments. Shoot organogenesis was higher at low concentrations of AgNO₃ and decreased with an increase in AgNO₃ concentration. The explants cultured on shoot induction medium (MS salts, vitamins, 1.0 mg/L BA, 1.0 mg/L NAA) with 1 mg/L of AgNO₃ produced the highest shoot regeneration with 2.6 shoots per explants and a browning index of 0.7. When the regenerated shoots were detached from the explants and cultured on MS medium, the shoots were elongated and rooted successfully.

• Progress in Superconductivity
• /
• v.12 no.1
• /
• pp.1-5
• /
• 2010

In this work we synthesized both MgB2 and Carbon doped MgB2 superconductor with Ag addition via high energy milling and substituent heat treatment. Heat treatments were performed at $900\;^{\circ}C$ for 30 min in flowing Ar gas. We varied amount of Ag powder. In a range of Ag powder was 0~5wt%. The effect of Ag was correlated with superconducting properties. The results show a slight decrease in critical temperature ($T_c$) and a reduction of critical current density ($J_c$) at high fields for the Ag-doped samples as compared to the un-doped samples. Reduction of $J_c$ may be due to the formation of MgAg compound.

• Biomolecules & Therapeutics
• /
• v.5 no.4
• /
• pp.412-418
• /
• 1997

General pharmacological properties of AG 60 (mixture of acriflavine and guanosine (1:1, w/w)), which has anticancer effect, following intramuscular administration were examined in terms of effects on central nervous system, gastrointestinal system, cardiovascular system, respiratory system and autonomic nervous system in mice, rats, guinea-pigs and rabbits. AG 60 at the dose of 15 mgtg had no influences on pentobarbital sleeping time, spontaneous motor activity, chemoshock produced by pentylenetetrazole solution, writhing syndromes induced by 0.8% acetic acid solution, and motor coordination of mice. However, AG 60 at the dose of 7.5 and 15 mg/kg caused significant decrease of normal body temperature 1 and/or 2 h after the administration. No influence on body temperature was observed at 3.75 mg/kg in mice. Gastric secretion of rat and intestinal motility of mice were not influenced by the dose of 15 mg/kg. In terms of autonomic nervous system, AG 60 did not show direct effect and inhibitory or augmentative action of histamine- or acetylcholine-induced contractions at the concentration of 5 mg/L in the isolated ileum of guinea-pig. The administration of 15 mg/kg of AG 60 did not affect mean arterial blood pressure and heart rate in rat. AG 60 (15 mg/kg) given to anesthetized rabbits showed no effect on respiratory rate.

• Journal of Acupuncture Research
• /
• v.34 no.3
• /
• pp.1-11
• /
• 2017

Objectives : The purpose of this study was to examine the effects of Acori Graminie Rhizoma Pharmacopuncture (PA-AG) at GV20 on cerebral ischemia-induced dementia in Mice. Methods : Mice were divided into the five following groups: normal, control, acupuncture, PA-AG (17 mg/kg), and PA-AG (34 mg/kg). All groups, except the normal group, had cerebral ischemia induced by occlusion of middle cerebral artery. The control group was not treated. The acupuncture, PA-AG (17 mg/kg), and PA-GA (34 mg/kg) groups were treated every other day with a total of 6 treatments. The effect of treatment was observed by Bax, Bcl-2, Bax/Bcl-2 ratio, cytochrome c, cresyl violet, and choline acetyltransferase staining. Results : In the PA-AG (34 mg/kg) group, the intensity of Bax was decreased and the intensity of Bcl-2 was increased. The Bax/Bcl-2 ratio also decreased in the PA-AG (34 mg/kg) group. The intensity of cytochrome c protein stain was decreased in the PA-AG (17 mg/kg) group. The density of neurons stained by cresyl violet and choline acetyltransferase (ChAT) was increased in the AT, PA-AG (17 mg/kg), and PA-AG (34 mg/kg) groups when compared with that of the control group. Conclusion : PA-AG at GV20 was effective on cerebral ischemia-induced dementia in mice.

• Korean Journal of Metals and Materials
• /
• v.49 no.6
• /
• pp.440-447
• /
• 2011

To improving the mechanical properties of Mg alloys at high temperature, we investigated the mechanical properties at high temperature and the change of microstructure of Mg-6 wt%Zn-0.4 wt%Mn and Mg-6 wt%Zn-0.4 wt%Mn-1 wt%Ag alloys on age treatment that have a stable MgZn phase at high temperature and $AgMg_4$ improving yield stress. In order to predict thermodynamic data of Mg alloys, a phase diagram and precipitation phase were calculated using a thermodynamic program, and it was confirmed that the MgZn and $AgMg_4$ phase existed as main precipitation in this alloys. The experimental data examined using DSC and XRD were comparable with the calculated data for reliability. In order to analysis the microstructure and precipitate phase during aging treatment, it was measured by SEM/EDS and TEM. Lastly, mechanical properties of the MgZn and $AgMg_4$ phase were measured by a tensile test at high temperature.

• Progress in Superconductivity and Cryogenics
• /
• v.5 no.3
• /
• pp.6-10
• /
• 2003

Silver nano-powder was added to Ma $B_2$ to make (Ag)$_{(x)wt.%}$(Mg $B_2$)$_{(l00-x)wt.%}$ (A $g_{x}$-Mg $B_2$) (10 $\leq$ x $\leq$ 50) composite superconductors to investigate the effect of the Ag nano-powder on the vortex pinning. Pellets made out of the mixed powder were put inside stainless steel tubes, which were sintered at 85$0^{\circ}C$ in Ar atmosphere. No impurity phase was identified for as-rolled samples. However, both the Mg $B_2$ and the A $g_{x}$-Mg $B_2$ composite pellets, when sintered, contain small amount of Mg $B_4$ and MgAg impurity phases. From the magnetization study, it was found that the flux pinning was improved in the high magnetic field region (> 3 T) only when 10w/o Ag was added to Mg $B_2$. The "two step" structures in ZFC M(T) curve gradually increased as the amount of Ag added increased. Pinning centers can be created by adding a suitable amount of Ag nano-powder which is not too large to increase the decoupling between the Mg $B_2$ grains.crease the decoupling between the Mg $B_2$ grains.

• Journal of the Korean Society for Heat Treatment
• /
• v.23 no.1
• /
• pp.10-16
• /
• 2010

The microstructure of Cu-Mg-P alloy sheet consisted of Cu matrix and very fine MgP precipitate, and it has been observed that the microstructure remains virtually unchanged by Ag additions up to 2%. Ag solutes were dissolved into the matrix and hardly found in the precipitates. The hardness increased with increase of the Ag content, while the conductivity slightly decreased. Strain hardening through cold rolling was found to be effective in improving the hardness, especially in high-Ag alloys. Aging treatment was conducted either before the first cold rolling or between the first and the final cold rolling, and the conductivity was significantly higher at the former case, regardless of the Ag content. Softening of Cu-Mg-P alloy sheet was remarkable above $400^{\circ}C$ and the Ag content did not show any significant effect on it.