• Korean Journal of Medicinal Crop Science
• /
• v.7 no.1
• /
• pp.1-6
• /
• 1999

Basic informations for direct somatic embryo formation in Rehmannja glutinosa Lib. were obtained in 500ml erlenmyer flask. The ratio of ammonium to nitrate nitrogen of 825(mg/l) : 1900(mg/l) was proper condition for somatic embryo formation from stem and petiole explants and 3% sucrose was the most effective carbon source. Full strength MS medium with 2mg/l BA was better than LS medium for somatic embryogenesis. The initial pH 5.7 of medium(full strength MS with 2.0mg/l BA and 0.1mg/l NAA) was good for embryo production. Potassium ion was taken up rapidly within 2 weeks. while $Ca^{++}$ and $Mg^{++}$ ion contents were almost constant during culture period. Sucrose hydrolysis occurred throughout the culture, while glucose and fructose were absorbed simultaneously from the third week of culture.

• Progress in Superconductivity
• /
• v.11 no.1
• /
• pp.8-12
• /
• 2009

We investigated the effects of the irradiation of light-ions on the superconducting $MgB_2$ thin films fabricated by using HPCVD. Deuterium and helium ions were irradiated on $MgB_2$ thin films by various doses, from $1{\times}10^{10}cm^{-2}\;to\;8{\times}10^{15}cm^{-2}$. During these experiments some reasonable results and unpredictable results have been obtained. The reasonable results are that the peak of the reduced maximum pinning force shifts by increasing the pinning sites in $MgB_2$ films and the slightly change of critical current density of films. We obtained some unusual results, which are the increasing of the transition temperature and the change of residual resistance ratio. Among the data of deuterium and helium ion irradiation experiments, the results of helium ion irradiation have most notable points so we will discuss mainly about helium irradiation experiments.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2002.08a
• /
• pp.625-627
• /
• 2002

MgO thin films were deposited on glass and (100) Si substrates by an Arc Ion Plating (AIP) equipment using a magnesium metal target at various oxygen gas flow. In this work, we investigated the relationship between the structural properties and the discharge characteristics of MgO coating layers. X-ray diffraction and AFM have been used to study behaviors of the structure and surface morphology. The optical transmittance and the ion induced secondary electron emission coefficient of the MgO films have been also measured. The resistivity of the deposited MgO films was gradually increased from 0.17 G ohm/${\square}$ to 0.35 G ohm/${\square}$ with the oxygen gas flow. The growth rate of the MgO coating layer was decreased with increasing the oxygen gas flow, while the optical transmittance was improved.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.9
• /
• pp.960-966
• /
• 2004

On the bases of the results from "Additive Coating of BaTiO$_3$ Powder using Sol Coating Method I", experimental condition was defined. Representative additives for BaTiO$_3$, that is to say, Mg, Ca and Mn were experimented. The sources of the metal ion were used by organometal complex. As added it, the stability of BaTiO$_3$ sol was evaluated. Mg and Ca were stable, however, The solubility limit of Mn-ATH was 0.05 mol ratio in Mn-ATH/sol. The solubility limit of Mg ion in BaTiO$_3$ was lower than 2 mol%. From the x Ray diffraction patterns, lattice parameters were different with temperature and additives, because the solubility of metal ion was varied in BaTiO$_3$. The dielectric constant of BaTiO$_3$ powders which coated with the 1.5 mol% Mg and calcined at 1200$^{\circ}C$ was increased with 20%.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2004.08a
• /
• pp.507-510
• /
• 2004

Oblique ion-induced secondary electron emission coefficient(${\gamma}$) with low energy ..and work function ${\phi}_{\omega}$(${\theta}$ = 0 and ${\theta}$ = 20) of the MgO thin film in AC-PDPs has been measured by ${\gamma}$-FIB system. The MgO thin film has been deposited from sintered material under electron beam evaporation method. The energy of $He^+$ ions used has been ranged from 50eV to 150eV. Oblique ion beam has been chosen to be 10 degree, 20 degree and 30 degree. It is found that the higher secondary electron emission coefficient(${\gamma}$) has been achieved by the higher oblique ion beam up to inclination angle of 30 degree than the perpendicular incident ion beam.

• Journal of Chest Surgery
• /
• v.18 no.1
• /
• pp.1-6
• /
• 1985

Isolated sinus node cells of the rabbit were used to assess the effects of extracellular Na, K, Ca and Mg concentrations on cardiac pacemaker activity. With intracellular glass micro-electrodes spontaneous action potentials of SA node were recorded and the effects of various ions and their blockers were analyzed in terms of the cycle length, the amplitude and the duration of action potentials, the results obtained were as follows. 1. Sodium reduction [up to 30%] decreased the amplitude of action potential and lengthened the cycle length. TTX, specific blocker of Na channel slightly lengthened the cycle length. 2. Increasing potassium ion concentration, the duration of action potential decreased and the frequency increased in 6mM, however, spontaneous action potential was stopped in 24 mM. Barium ion known to be decreasing K conductance increased the duration of action potential but no significant change in the cycle length was noticed. 3. Calcium ion has shortening effect on the duration and the cycle length of action potential but not with dose-dependent manner. Cadmium ion .[0.02mM] lengthened cycle length and the duration of action potential. 4. Increasing the concentration of magnesium ion the cycle length was lengthened, significantly.

• Proceedings of the KIEE Conference
• /
• 1997.07e
• /
• pp.1752-1754
• /
• 1997

The Kaufman type ion beam source with focusing lens was prepared to measure $\gamma$-coefficient of MgO thin film. Initial discharge of the system was started with the discharge voltage of 25V, the cathode filament current of 5.5A at the constant magnetic field of 150G. The system shows the maximum ion current density of $120{\mu}A/cm^2$, energy dispersion of 200eV and beam divergence of $30^{\circ}$ under the condition of Ar gas pressure $2.5{\times}10^{-4}Torr$, the beam voltage of 500V, the discharge voltage of 90V, the accelerator voltage of -200V and the cathode filament current of 6.1A. When the focusing lens was installed onto the ion beam source, the spreadness diameter of ion beam was about 10mm.

• Analytical Science and Technology
• /
• v.27 no.6
• /
• pp.333-338
• /
• 2014

A simple and sensitive analytical method for fluoride in urine by ion selective electrode (ISE) method was presented. Traditional buffer for fluoride determination using ISE is acetate-based one. Researchers have pointed out some drawbacks of the buffer for fluoride ISE analysis, and some other buffers including citrate-ammonium buffer and MES buffer have been studied for accurate determination of fluoride in urine here. These buffers provided promising results in environmental field, and this author focused on overcoming the interference of co-existing aluminium. The results show that MES-CyDTA buffer gave the best recovery with accuracy of 95-97.5% and precision of 1.9-7.9% for reference sample of 1.8-7.8 mg/L fluoride in urine, with smaller amount of samples and shorter analysis time compared with the traditional method which used acetate buffer. The method was applied to field samples, and which showed urinary of $0.98{\pm}0.38mg/g$ creatinine for workers in electric cable manufacturing factory (n=15) and $0.59{\pm}0.30mg/g$ creatinine for non-exposed workers (n=12).

• Journal of the Korean Ceramic Society
• /
• v.24 no.1
• /
• pp.77-85
• /
• 1987

Hardened cement paste is mainly affected by corrosion of sulphate and chlorine ions in sea water. In this investigation, many specimens were made with the cement clinker minerals such as C3S, C3A, C4AF and their mixture according to cement composition added various blending materials. After the specimens were immersed in 4% MgSO4 and MgCl2 solutions, the product of reaction, the microstructure of specimen and Ca+2 ion leached in the solution were studied. The formation of Ca(OH)2 in the specimen of C3S is reduced relatively by adding pozzolanic admixtures. The chlorine ion is easily diffuse into the C3S specimen and produced CaCl2 compound, and it makes the specimen porous by leaching out itself into the solution. The specimen of C3A, C4AF are broken down by expanding reaction of ettringite and gypsum compound produced in the MgSO4 solution. At a later period, the ettringite is transformed into gypsum and 5MgO.2Al2O3·15H2O. The C3A in the MgCl2 solution combines chlorine ion to form Friedel's salt and prevents the diffusion reaction of chlorine ion into the specimen. Granulated slag shows inferior effect on the resistance of the specimen in MgSO4 solution by forming ettringite and gypsum, but good result in MgCl2 solution. Pozzolanic materials, on the whole, offer noticable effect on the resistance of the specimen in both solutions.

• Environmental Engineering Research
• /
• v.16 no.3
• /
• pp.165-173
• /
• 2011

The equilibrium and kinetic adsorption of arsenic on six different adsorbents were investigated with one synthetic and four natural types (two surface and two ground) of water. The adsorbents tested included magnetic ion exchange resins (MIEX), hydrous ion oxide particles (HIOPs), granular ferric hydroxide (GFH), activated alumina (AA), sulfur modified iron (SMI), and iron oxide-coated microsand (IOC-M), which have different physicochemical properties (shape, charge, surface area, size, and metal content). The results showed that adsorption equilibriums were achieved within a contact period of 20 min. The optimal doses of adsorbents determined for a given equilibrium concentration of $C_{eq}=10\;{\mu}g/L$ were 500 mg/L for AA and GFH, 520-1,300 mg/L for MIEX, 1,200 mg/L for HIOPs, 2,500 mg/L for SMI, and 7,500 mg/L for IOC-M at a contact time of 60 min. At these optimal doses, the rate constants of the adsorbents were 3.9, 2.6, 2.5, 1.9, 1.8, and 1.6 1/hr for HIOPs, AA, GFH, MIEX, SMI, and IOC-M, respectively. The presence of silicate significantly reduced the arsenic removal efficiency of HIOPs, AA, and GFH, presumably due to the decrease in chemical binding affinity of arsenic in the presence of silicate. Additional experiments with natural types of water showed that, with the exception of IOC-M, the adsorbents had lower adsorption capacities in ground water than with surface and deionized water, in which the adsorption capacities decreased by approximately 60-95%.