• Archives of Pharmacal Research
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• v.23 no.4
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• pp.360-366
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• 2000

The in vivo binding of dopamine (DA) radioligands to $D_2$receptors can be affected by competition with endogenous dopamine. In the present study, we used a brain slice preparation that provides more controlled conditions than in vivo preparations in order to examine the relationship between synaptic DA and the binding of [$^3H$] raclopride to $D_2$receptors. We also estimated the synaptic DA concentration in rat striatal slices by determining the changes in [$^3H$] raclopride binding. To correlate the changes in [$^3$H]raclopride binding with the concentration of synaptic DA, the kinetic parameters were determined. [$^3H$] Raclopride reached equilibrium binding conditions within two hours. The K value for DA in inhibiting [$^3$H]raclopride binding was about 2.2 nM. The increase in synaptic DA evoked by electrical stimulation decreased the striatal binding of [$^3H$] raclopride in a frequency-dependent manner. Increases in the DA concentration evoked by amphetamine (AMPH) or cocaine decreased [$^3H$] raclopride binding by 74% or 20%, respectively, corresponding to increases in the synaptic DA concentrations of 1.6 nM or 0.6 nM, respectively. Pargyline also decreased [$^3H$] raclopride binding by 36%corresponding at a concentration of 1.2 nM. In contrast, the depletion of synaptic DA by $\alpha$-methyl-p-tyrosine ($\alpha$-MpT) increased the specific binding of [$^3H$] raclopride by 43%when the DA concentration was decreased to 0.7 nM. The changes in the DA concentration at the synapse were responsible for the changes in the striatal binding of [$^3H$] raclopride. The values calculated in this study may therefore approximate the changes in the synaptic DA concentration in rat striatal slices following manipulation.

• Journal of ILASS-Korea
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• v.25 no.3
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• pp.132-138
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• 2020

N₂O is hazardous atmosphere pollution matter which can damage the ozone layer and cause green house effect. There are many other nitrogen oxide emission control but N₂O has no its particular method. Preventing further environmental pollution and global warming, it is essential to control N₂O emission from industrial machines. In this study, the thermal decomposition experiment of N₂O gas mixture is conducted by using cylindrical reactor to figure out N₂O reduction and NO formation. And CHEMKIN calculation is conducted to figure out reaction rate and mechanism. Residence time of the N₂O gas in the reactor is set as experimental variable to imitate real SNCR system. As a result, most of the nitrogen components are converted into N2. Reaction rate of the N₂O gas decreases with N₂O emitted concentration. At 800℃ and 900℃, N₂O reduction variance and NO concentration are increased with residence time and temperature. However, at 1000℃, N₂O reduction variance and NO concentration are deceased in 40s due to forward reaction rate diminished and reverse reaction rate appeared.

• JSTS:Journal of Semiconductor Technology and Science
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• v.3 no.2
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• pp.96-101
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• 2003

Direct evidence on the incorporation of high concentration of oxygen into undoped AlGaN layers for the AlGaN/GaN heterostuctures is provided by scanning photoemission microscopy using synchrotron radiation. In-situ annealing at $1000^{\circ}C$ resulted in a significant increase in the oxygen concentration at the AlGaN surface due to the predominant formation of Al-O bonds. The oxygen incorporation into the AlGaN layers resulting from the high reactivity of Al to oxygen can enhance the tunneling-assisted transport of electrons at the metal/AlGaN interface, leading to the reduction of the Schottky barrier height and the increase of the sheet carrier concentration near the AlGaN/GaN interface.

• Journal of Environmental Science International
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• v.13 no.2
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• pp.175-180
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• 2004

A prompt gamma-ray neutron activation (PGNA) system was simulated by the Monte Carlo N-Particle transport code (MCNP-4A) to estimate the level at which the scattered photon fluence rate, the absolute efficiency of the HPGe-detector, the volume of the concrete sample and the $^{35}$ /Cl(n, ${\gamma}$) reaction rate in this sample contribute to the count rate in the NaCl concentration measurement. The n- ${\gamma}$ fluence rates at the ST-2 beam tube exit of the HANARO reactor were used as input data, and the GAMMA-X type HPGe detector was modeled to tally 1.1649 MeV ${\gamma}$ -rays emitted from the $^{35}$ Cl(n, ${\gamma}$) reaction in the concrete sample. For three cylindrical concrete samples of 13.8, 46.8 and 157.1 ㎤ volumes, respectively, the relations between the NaCl weight fractions of 0.1, 1, 2 and 5 % in each of the concrete samples and the 1.1 649 MeV pulses created in the HPGe detector model were studied. As a result, it was found that the count rate at the same NaCl concentration nearly depends on the volume of the samples in a simulated condition of the same NaCl concentration samples, and that the linearities of the NaCl concentration calibration curves were reasonable in the narrow range of the NaCl weight fraction.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.1
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• pp.17-23
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• 2005

The switching characteristics of MOS-Controlled Thyristor(MCT) is studied with variation of the channel length and impurity concentration in ON and OFF FET channel. The proposed MCT power device has the lateral structure and P-epitaxial layer in substrate. Two dimensional MEDICI simulator and PSPICE simulator are used to study the latch-up current and forward voltage-drop from the characteristics of I-V and the switching characteristics with variation of channel length and impurity concentration in P and N channel. The channel length and N impurity concentration of the proposed MCT power device show the strong affect on the transient characteristics of current and power. The N channel length affects only on the OFF characteristics of power and anode current, while the N doping concentration in P channel affects on the ON and OFF characteristics.

• Journal of ILASS-Korea
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• v.4 no.1
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• pp.27-33
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• 1999

An experimental study has been conducted to clarify the effect of vapor on droplet evaporation. Droplets of water, ethanol, n-hexadecane and n-heptane were exposed in air stream. Temperature, pressure, and flow velocity in the ambient air are 470K, 1 atm, and 2m/s, respectively. Measurements are carried out for the wide range of water vapor concentration$(0%\sim40%)$. To obtain the time histories of droplet diameter, suspended droplet in hot and humid air stream was synchronized with a back flash light, and enlarged droplet images were taken on a CCD camera. With the vapor concentration increasing, the evaporation rate constant of water droplet decrease slightly and the droplet of ethanol and n-heptane increase actively. The evaporation rate constant of n-hexadecane which has higher boiling point than water increases within around 30% of the concentration.

• Advances in Traditional Medicine
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• v.8 no.2
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• pp.192-195
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• 2008

The effect of aqueous and alcoholic extract of roots of Berberis aristata was studied on the spontaneous movements of the whole worm (w.w) preparation and nerve muscle (n.m) complex of cattle filarial parasite Setaria cervi and on the survival of microfilariae. Only aqueous extract could inhibit the spontaneous movements of S. cervi, characterized by initial stimulation followed by reversible paralysis. The concentration required to produce similar effect on n.m complex was less as compared to the w.w. The lethal concentration 50 and lethal concentration 90 for aqueous extract were 48 ng/ml and 65 ng/ml.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.133-138
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• 2001

In this study, quantitative nitric oxide concentration distributions are investigated in the laminar nonpremixed $H_2/N_2$ flames by laser-induced fluorescence (LIF). The measurements are taken in flames for different $N_2$ dilution ratios varying from 20${\sim}$80%, and fuel now rate is fixed as lslpm. The NO A-X (0,0) vibrational band around 226 nm is excited using a XeCl excimer-pumped dye laser. We applied same excitation line used in $CH_4$ premixed flame. Overall, NO concentration was rapidly decreased with $N_2$ addition and we could not measure the concentration any longer for $N_2$ dilution above 80%.

• Journal of Applied Biological Chemistry
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• v.65 no.4
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• pp.337-341
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• 2022

In this study, the effect of the combined use of a lipid-soluble n-hexane extract of red ginseng marc (HERGM) and water-soluble arginine, which exhibits anticaries activity, on the growth of Streptococccus mutans was investigated. As a result of checkerboard assay, HERGM and arginine showed a synergistic effect in inhibiting the growth of S. mutans with a fractional inhibitory concentration index of 0.396. Combination treatments of HERGM and arginine resulted in leakage of nucleic acid components and decrease in the viable cell counts of S. mutans, all of which were proportional to the concentration of HERGM. In conclusion, the synergistic effect of HERGM and arginine on the growth inhibition of S. mutans is mainly attributed to HERGM.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.7
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• pp.941-947
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• 2000

Three fistulated Malaysian local bulls were used in a $3{\times}3$ Latin square design to determine the effects of different levels of concentrate with oil palm (Elaeis guineensis Jacq.) frond (OPF) on rumen pH and $NH_3$-N concentration, and DM degradability of different fractions of OPF. Three diets namely, 60% OPF pellet and 40% concentrate (Diet 1), 50% OPF pellet and 50% concentrate (Diet 2) and 40% OPF pellets and 60% concentrate (Diet 3) were used. The levels of concentrate in the diets affected rumen pH and $NH_3$-N concentration. The pH and $NH_3$-N concentration almost in all hourly samples did not show any difference (p>0.05) among the diets except the 6 h and 9 h samples. The highest (p<0.01) $NH_3$-N concentration was obtained on Diet 3 followed by Diet 2 and Diet 1, but there was a slightly higher (p>0.05) pH on Diet 1. The $NH_3$-N concentrations of rumen liquor at 9 h sampling on Diet 1 and Diet 2 were below the critical level (50 mg/liter) required for efficient fermentation of fibrous feeds. The in sacco DM degradation of different fractions of OPF was affected by diets. The DM degradation of fractions of OPF was higher on Diet 3, which showed differences (p<0.01) with the other diets. It was found that a higher level of concentrate (60%) with OPF gave a higher rumen $NH_3$-N concentration that increased the DM degradation of OPF fractions. The results showed that OPF could support an efficient rumen function in terms of $NH_3$-N concentration and pH when ${\leq}50%$ in the diet. A higher level of OPF (>50%) does not support an efficient rumen fermentation in terms of $NH_3$-N concentration, and resulted in lower DM degradation values of the fractions. The results suggested that there is a need to supplement additional nitrogen to OPF based diets.