• Resources Recycling
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• v.18 no.1
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• pp.30-37
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• 2009

Distribution diagram of Pt(IV), Pd(II), and Rh(III) in HCl solution was obtained as a function of HCl concentration from 0.001 to 10 M by considering complex formation reaction together with mass balance. When HCl concentration was higher than 0.1 M, most of Pt and Pd in HCl solution exist as $PtCl_6^{2-}$ and $PtCl_4^{2-}$. The concentration of HCl had a feat effect on the speciation of Rh(III). As HCl concentration increases from 0.1 to 10 M, the pedominant species changes from $PhCl_5^{2-}$ to $PhCl_6^{3-}$. Interaction parameters of $PtCl_6^{2-}$ and $PdCl_4^{2-}$ with hydrogen ion were evaluated from the solvent extraction data of Pt and Pd reported in the literature.

• Resources Recycling
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• v.20 no.4
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• pp.65-70
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• 2011

Environmental friendly leaching process for the recovery of cobalt and lithium from the $LiCoO_2$ was investigated by organic acids as a leaching reagent. The experimental parameters, such as organic acid type, concentrations of leachant and hydrogen peroxide, reaction time and temperature as well as the pulp density were tested to obtain the most effective conditions for the leaching of cobalt and lithium. The results showed that the latic acid was the most effective leaching reagent for cobalt and lithium among the organic acids and was reached about 99.9% of leaching percentage respectively. With the increase of the concentration of citric acid, hydrogen peroxide and temperature, the leaching rate of cobalt and lithium increased. But the increase of pulp density decreased the leaching rate of cobalt and lithium.

• Journal of the Korean Chemical Society
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• v.21 no.4
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• pp.276-283
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• 1977

Reduction of dichromate at a platinum cathode in acid solution was studied by cyclic voltammetry and controlled potential electrolysis. Cathodic polarization curve consisted of three waves in unbuffered solution of potassium dichromate having initial pH ranges 1.5∼4.0, with sodium sulfate as the supporting electrolyte. Relative heights of the first and the second waves were, respectively, a function of chromium (Ⅵ) concentration and activity of hydrogen ion, but that of the third wave was not proportional to both of them. The current of the first two peaks were proportional to the sweep rate of potential (${\nu}$), while that of the last peak vs. ${\nu}^{1/2}$ was linear at the sweep rate of less than 50mV/sec. By the controlled potential electrolysis, the reduction of chromium (Ⅵ) was almost completely suppressed at potentials more negative than the last peak and at initial pH's above ca. 2.3 of unbuffered solution. Therefore, these peaks represented, respectively, $Cr_2O_7^{2-}{\to}Cr^{3+},\;2H^+{\to}H_2$ and the formation of a cathodic film.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.2
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• pp.223-230
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• 2011

An electrolytic oxidation process was applied to remove odorous compounds from non-point odor sources including wastewater pipelines and manholes. In this study, a distance between the anode and the cathode of the electrolytic process was varied as a system operating parameters, and its effects on odor removal efficiencies and reaction characteristics were investigated. Odor precursors such as sediment organic matters and reduced sulfur/nitrogen compounds were effectively oxidized in the electrolytic process, and a change in oxidation-reduction potential (ORP) indicated that an stringent anaerobic condition shifted to a mild anoxic condition rapidly. At an electrode distance of 1 cm and an applied voltage of 30 V, a system current was maintained at 1 A, and the current density was 23.1 $mA/cm^{2}$. Under the condition, the removal efficiency of hydrogen sulfide in gas phase was found to be 100%, and 93% of ammonium ion was removed from the liquid phase during the 120 minute operating period. Moreover, the sulfate ion (${SO_4}^{2-}$) concentration increased about three times from its initial value due to the active oxidation. As the specific power consumption (i.e., the energy input normalized by the effective volume) increased, the oxidation progressed rapidly, however, the oxidation rate was varied depending on target compounds. Consequently, a threshold power consumption for each odorous compound needs to be experimentally determined for an effective application of the electrolytic oxidation.

• The Korean Journal of Physiology
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• v.24 no.1
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• pp.161-170
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• 1990

The effects of $H^{+}$ on the arterial contraction and their mechanisms were investigated in the renal artery of a rabbit. The helical strips of isolated renal artery were immersed in the HEPES-buffered or $CO_{2}/HCO_{3}^{-}$-buffered Tyrode's solution. The contractions induced by agonists (norepinephrine, histamine, serotonin and angiotensin II) or high $K^{+}$ were observed with change of extracellular or intracellular $H^{+}$ concentration. The contractions induced by norepinephrine, histamine, serotonin, angiotensin II or high $K^{+}$ in HEPES-buffered Tyrode's solution were inhibited by increase in extracellular $H^{+}$ concentration and potentiated by decrease in extracellular $H^{+}$ concentration. The degrees of these effects were most evident in the contraction induced by serotonin and angiotensin II, moderate in those by histamine and high $K^{+}$, and least in those by norepinephrine. Maximal contraction by norepinephrine, histamine and high $K^{+}$ were not influenced by change in extracellular $H^{+}$ concentration, but influenced in those contration by serotonin and angiotensin II. The attenuated contractions by an acidic pH were not returned to the level of contraction at normal pH (7.4) by elevation of extracellular $Ca{2+}$ concentration. The agonists (norepinephrine, histamine and serotonin)-induced contractions in $Ca{2+}$-free Tyrode's solution were also attenuated by increase in extracellular $H^{+}$ concentration and potentiated by decrease in extracellular $H^{+}$ concentration. Elevation of $Pco_{2}$ in the $CO_{2}/HCO_{3}^{-}$-buffered Tyrode's solution, which increase the intracellular $H^{+}$ concentration, at constant extracellular pH (7.4), increased the contraction by 30 mM $K^{+}$. From the above results, it is suggested that the decrease in contractions by increase in extracellular $H^{+}$ concentration may be resulted from that $H^{+}$ make the receptors less sensitive to agonists and cell membrane hyperpolarize and then inhibit the $Ca{2+}$ influx as well as $Ca{2+}$ release from intracellular $Ca{2+}$ storage site.

• Archives of Pharmacal Research
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• v.9 no.3
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• pp.163-167
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• 1986

Twenty six urea analogues, most of which have already been approved for human use, were tested for their antiurease activity in vitro. Cell-free extracts obtained from a clinical isolate of Proteus mirabilis was used as the source of enzyme. Acetohydroxamic acid which is a proven potent urease inhibitor but not approved for human use was again shown to be the most active compound among the tested. Phenacemide, cycloserine, and deferoxamine were demonstrated to be moderate inhibitors. Oxtetracycline, trimethoprim, and cefamandole revealed a demonstrable antiruease activity, but only at very high concentrations. The antiurease activity of cycloserine, trimethoprim, and cefamandole was pH dependent-only active at acidic pH. The inhibitory activity of acetohydroxamic acid however was independent of change in pH. The inhibitory activity of acetohydroxamic acid however was independent of change in pH. Hydrogen ion concentration plays an important role in urease activity and acidification (pH 5. 5) alone eliminates approximately 65% of the enzymic activity. Adjustment of pH therefore appears to be an important adjunct in reducing unrease activity and should always be studied to maximize the effcacy of antiurease compounds under investigation.

• Journal of Korean society of Dental Hygiene
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• v.19 no.6
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• pp.1077-1087
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• 2019

Objectives: The purpose of this study was to analyze the risk of dental caries and erosion associated with beverage consumption by measuring the sugar content and acidity of beverages for children, marketed in general food stores and cooperative living associations in Korea. Methods: Sixty types of children's beverages marketed in Korea were selected for the study. Calories, sodium, and carbohydrates in the nutrients per 100 ml, the sugar content, and pH of each beverage were measured. Frequency analysis, independent t-test, and one-way ANOVA were performed (p<0.05). Results: There was no significant difference in sugar content, calories, sodium, and carbohydrate content of regular and cooperative beverages, but the pH of cooperative beverages was significantly higher. Moreover, the mixed drinks had significantly lower sugar content, calories, and carbohydrates than fruit and juice, but the sodium content was significantly higher. Conclusions: When choosing beverages for children, caregivers should be able to easily access information about their impact on the child's oral health. Efforts should be made to maintain appropriate levels of sugar and acidity in beverages for children.

• Journal of the Korean Wood Science and Technology
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• v.42 no.1
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• pp.27-33
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• 2014

The characteristic of vegetation mat prepared from miscanthus, waste wood chip, perlite and pulp slurry was investigated. The pore rate was increased with amount of pulp slurry. The hydraulic conductivity decreased with the amount of miscanthus in the condition mixed with each other raw materials. With the miscanthus amount, the soil hardness was increased. The peel strength decreased with the mount of miscanthus amount in all case. Hydrogen ion concentration (pH) was the overall alkaline. The MOR of miscanthus based vegetation mat was decreased with the amount miscanthust.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.4
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• pp.321-327
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• 1996

A back titration method was suggested to determine the exchangeable acidity of soil originated from exchangeable aluminum and adsorbed hydrogen ion in relation to minimizing its titration error. In this method. soils are treated by neutral salt solution whose concentration is the same as soil solution suspended by distilled water. And then. its pH is adjusted at 3, using 1 N HCl solution and back-titrated by 0.1 N NaOH solution containing 1 N NaCl. The results of the suggested back-titration showed the possibility of practical application with linear relationship to that of standard method.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.199-201
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• 2002

Cancer therapy using high-energy $^{12}$ C ions is successfully under way at HIMAC, Japan. An alternative beam to $^{12}$ C is $^{11}$ C ions. The merit of $^{11}$ C over $^{12}$ C is its capability for monitoring spatial distribution of the irradiated $^{11}$ C by observing the $\beta$$^{+}$ decay with a good position resolution. One of the several problems to be solved before its use for therapy is the amount of nuclear interaction that deteriorates the dose concentration owing to the Bragg curve. Utilizing the dedicated secondary beam course for R&D studies at HIMAC, we measured the total energy loss of $^{11}$ C ions in a scintillator block that simulates the soft tissue in human bodies. In addition to the total absorption $^{11}$ C peak, non-negligible bump-shaped contribution is observed in the energy spectrum. The origin of the bump contribution can be nuclear interaction of the incident $^{11}$ C ions with hydrogen and carbon atoms. Further studies to reduce the ambiguity in dose distribution are mentioned.