• Journal of Korean Society of Forest Science
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• v.88 no.2
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• pp.149-156
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• 1999

This research was carried out to investigate the effects of the different tree species(Q. spp., L. leptolepis and P. koraiensis) about the chemical properties of throughfall and stemflow, to purify the acid rain at Kyung Hee Univ. experimental forest, Gwangju-gun, Kyunggi-do. The water quality of the precipitation, throughfall and stemflow in each forest stands were analyzed chemically. The throughfall pH ranges were Q. spp.(pH 4.96-6.34), L. leptolepis(pH 3.96-6.41) and P. koraiensis(pH 4.11-6.36), and the stemflow pH ranged Q. spp.(pH 4.33-6.05), L. leptolepis(pH 3.59-6.09) and P. koraiensis(pH 3.60-6.13). pH values of throughfall and stemflow to the precipitation were Q. spp. higer than L. leptolepis and P. koraiensis, while distribution range was small. Therefore, buffering capacity about the precipitation in the tree species trended Q. spp. bigger than L. leptolepis and P. koraiensis. Nearly all concentration of dissolved elements were precipitation${\leq}$throughfall${\leq}$stemflow. The cation ($Ca^{2+}$, $Mg^{2+}$, $K^+$ and $NH_4{^+}$), and anion($Cl^-$ and $NO_3{^-}$) were increased. Especially the concentration of $Mg^{2+}$, $K^+$, $NH_4{^+}$ and $Cl^-$ were noticeable. In comparing concentration of dissolved elements of throughfall with each tree species, $Ca^{2+}$ concentration was Q. spp.$NH_4{^+}$ was Q. spp.

• Applied Biological Chemistry
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• v.37 no.3
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• pp.143-147
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• 1994

Four samples of commercially manufactured yogurts (plain, drinking type) were purchased and evaluated their physico-chemical properties, buffering capacity. And the survival rate of lactic acid bacteria and their ${\beta}-galactosidase$ activity under the acidic conditions (in vitro) were investigated. The values of pH, titratable acidity, viscosity and viable cell counts of yogurts were $3.71{\sim}4.08$, $0.990{\sim}1.045%$, $256{\sim}3164\;cps.$ and $10^8{\sim}10^9\;cfu/ml$, respectively. The volume of 1.0 M-HCl required to reduce the pH of yogurt (50 ml) to minus 2 value was $3.58{\sim}4.33\;ml$. When commercial yogurts were incubated at $37^{\circ}C$ for 120 minutes under the acidic conditions (pH 3.5, 2.5, 1.5), the survival rates of lactic acid bacteria in yogurt were $3.5{\times}10^{-2}{\sim}3.6{\times}10^{-1}%$ at pH 2.5, $8.3{\times}10^{-5}{\sim}4.2{\times}10^{-3}%$ at pH 1.5, respectively, but there was no significant difference at pH 3.5. The remaining activities of ${\beta}-galactosidase$ were $9.4{\sim}36.2%$ at pH 2.5, $4.2{\sim}19.0%$ at pH 1.5, respectively. These results suggested that a significant number of lactic acid bacteria in yogurt might be destroyed in the hostile environment of the stomach, but ${\beta}-galactosidase$ activity from yogurt might be somewhat maintained probably due to the protecting effect by its cell wall and membrane.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.2
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• pp.352-367
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• 1998

Intracellular pH (pHi) plays an important role in the regulation of cellular processes by influencing the acitivity of various enzymes in cells. Therefore, almost every type of mammalian cell possesses an ability to regulate its pHi. One of the most prominent mechanisms in the regulation of pHi is $Na^+/H^+$ exchanger. This exchanger has been known to be activated when cells are stimulated by the binding of agonist to the muscarinic receptors. Therefore, the aims of this study were to compare the rates of $H^+$ extrusion through $Na^+/H^+$ exchanger before and during muscarinic stimulation and to investigate the possible existence of $HCO_3^-$ transporter which is responsible for the continuous supply of $HCO_3^-$ ion to saliva. Acinar cells were isolated from the rat mandibular salivary glands and loaded with pH-sensitive fluoroprobe, 2', 7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein(BCECF), for 30min at room temperature. Cells were attached onto the coverglass in the perfusion chamber and the changes in pHi were measured on the iverted microscope using spectrofluorometer. 1. By switching the perfusate from $HCO_3^-$-free to $HCO_3^-$-buffered solution, pHi decreased by $0.39{\pm}0.02$ pH units followed by a slow increase at an initial rate of $0.04{\pm}0.007$ pH units/min. The rate of pHi increase was reduced to $0.01{\pm}0.002$ pH units/min by the simultaneous addition of 1 mM amiloride and $100{\mu}M$ DIDS. 2. An addition and removal of $NH_4^+$ caused a decrease in pHi which was followed by an increase in pHi. The increase of pHi was almost completely blocked by 1mM amiloride in $HCO_3^-$-free perfusate which implied that the pHi increase was entired dependent on the activation of $Na^+/H^+$ exchanger in $HCO_3^-$-free condition. 3. An addition of $10{\mu}M$ carbachol increased the initial rate of pHi recovery from $0.16{\pm}0.01$ pH units/min to $0.28{\pm}0.03pH$ units/min. 4. The initial rate of pHi decrease induced by 1mM amiloride was also increased by the exposure of the acinar cells to $10{\mu}M$ carbachol ($0.06{\pm}0.008pH$ unit/min) compared with that obtained before carbachol stimulation ($0.03{\pm}0.004pH$ unit/min). 5. The intracellular buffering capacity ${\beta}1$ was $14.31{\pm}1.82$ at pHi 7.2-7.4 and ${\beta}1$ increased as pHi decreased. 6. The rate of $H^+$ extrusion through $Na^+/H^+$ exchanger was greatly enhanced by the stimulation of the cells with $10{\mu}M$ carbachol and there was an alkaline shift in the activity of the exchanger. 7. An intrusion mechanism of $HCO_3^-$ was identified in rat mandibular salivary acinar cells. Taken all together, I observed 3-fold increase in $Na^+/H^+$ exchanger by the stimulation of the acinar cells with $10{\mu}M$ carbachol at pH 7.25. In addition, I have found an additional mechanism for the regulation of pHi which transported $HCO_3^-$ into the cells.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.231-239
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• 2006

In this study, we evaluated the efficiency of using sulfur-$CaCO_3$ complex pellet in the sulfur oxidizing autotrophic denitrification process for synthetic wastewater with high $CaCO_3$ concentration. The sulfur-$CaCO_3$ complex pellet was packed in reactor(R4). Influent ${NO_3}^--N$ loading rate was from 200 to $1,000g/m^3{\cdot}day$. During the operation, average denitrification efficiency of R4 was above 95%. Particularly, the denitrififation rate at $1,000g/m^3{\cdot}day$ loading was 98.96% for R4. High ${NO_3}^--N$ removal efficiency was determined in R4 compared with other reactors. Through $Ca^{2+}$ and alkalinity analyses, we calculated the supplied alkalinity from the packed $CaCO_3$ in the reactor. Sulfur-$CaCO_3$ complex pellet more effectively supplied alkalinity through the dissociation of $CaCO_3$ as compared with other media. Based on these results, sulfur-$CaCO_3$ complex pellet increased the pH buffering capacity while also providing the carbon source to the denitrifying bacteria. Denitrification efficiency of R4 was also higher than other reactors. ESEM pictures of sulfur-$CaCO_3$ complex pellet show higher porosity than that of the granular sulfur. Hence, more denitrifying bacteria attached on the sulfur-$CaCO_3$ complex pellet than on granular sulfur. It can be concluded that the sulfur-$CaCO_3$ complex pellet is a more suitable media for a sulfur oxidizing autotrophic denitrification process as it provides high denitrification efficiency.

• Journal of Chest Surgery
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• v.37 no.8
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• pp.632-643
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• 2004

Background: The Histidine-Tryptophan-Ketoglutarate (HTK) solution has been shown to provide the excellent myocardial protection as a cardioplegia. The HTK solution has relatively low potassium as an arresting agent of myocardium, and low sodium content, and high. concentration of histidine biological buffer which confer a buffering capacity superior to that of blood.. Since HTK solution has an excellent myocardial protective ability, it is reported to protect myocardium from ischemia for a considerable time (120 minutes) with the single infusion of HTK solution as a cardioplegia. The purpose of this study is to evaluate the cardioprotective effect of HTK solution on myocardium when the ischemia is. exceeding 120 minutes at two different temperature (10 to 12$^{\circ}C$, 22 to 24$^{\circ}C$) using the Langendorff apparatus, Material and Method: Hearts from Sprague-Dawley rat, weighing 300 to 340 g, were perfused with Krebs-Henseleit solution at a perfusion pressure of 100 cm $H_2O$. After the stabilization, the heart rate, left ventricular developed pressure (LVDP), and coronary flow were measured. Single dose of HTK solution was infused into the ascending aorta of isolated rat heart and hearts were preserved at four different conditions. In group 1 (n=10), hearts were preserved at deep hypothermia (10∼12$^{\circ}C$) for 2 hours, in group 2 (n=10), hearts were preserved at moderate hypothermia (22∼24$^{\circ}C$) for 2 hours, in group 3 (n=10), hearts were preserved at deep hypothermia for 3 hours, and in group 4 (n=10), hearts were preserved at moderate hypothermia for 3 hours. After the completion of the preservation, the heart rate, left ventricular developed pressure, and coronary flow were measured at 15 minutes, 30 minutes, and 45 minutes after the initiation of reperfusion to assess the cardiac function. Biopsies were also done and mitochondrial scores were counted in two cases of each group for ultrastructural assessment. Result: The present study showed that the change of heart rate was not different between group 1 and group 2, and group 1 and group 3. The heart rate was significantly decreased at 15 minutes in group 4 compared to that of group 1 (p<0.05 by ANCOVA). The heart rate was recovered at 30 minutes and 45 minutes in group 4 with no significant difference compared to that of group 1. The decrease of LVDP was significant at 15 minutes, 30 minutes and 45 minutes in group 4 compared to that of group 1 (p < 0.001 by ANCOVA). Coronary flow was significantly decreased at 15 minutes, 30 minutes, and 45 minutes in group 4 compared to that of group 1 (p < 0.001 by ANCOVA). In ultrastructural assessment, the mean myocardial mitochondrial scores in group 1, group 2, group 3, and group 4 were 1.02$\pm$0.29, 1.52$\pm$0.26, 1.56$\pm$0.45, 2.22$\pm$0.44 respectively. Conclusion: The HTK solution provided excellent myocardial protection regardless of myocardial temperature for 2 hours. But, when ischemic time exceeded 2 hours, the myocardial hemodynamic function and ultrastructural changes were significantly deteriorated at moderate hypotherma (22∼ 24$^{\circ}C$). This indicates that it is recommended to decrease myocardial temperature when myocardial ischemic time exceeds 2 hours with single infusion of HTK solution as a cardioplegia.