• Bulletin of the Korean Chemical Society
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• v.32 no.12
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• pp.4316-4320
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• 2011

The effects of various hydroxide compounds on base stacking (BS) were investigated for pre-concentration of DNA molecules in capillary electrophoresis (CE). In BS, hydroxide ions ($OH^-$) were electrokinetically introduced after DNA sample injection. A neutralization reaction occurred between the $OH^-$ and $Tris^+$ of the running buffer, which resulted in a zone of lower conductivity. Within the low conductivity zone of the high electric field, the DNA molecules moved more rapidly and were concentrated in front of the low conductivity zone. At the same BS conditions of CE, the enhanced sensitivity of the DNA samples was dependent on the kind of multivalent cations in the hydroxide compounds. Except for LiOH, the hydroxide compounds with monovalent cations showed more effective BS than those with divalent cations because of solubility, ionic strength and electronegativity. The order of hydroxide compounds that enhance the detection sensitivity of DNA molecules was as follows: NaOH > $NH_4OH$ > KOH > $Ba(OH)_2$ > $Sr(OH)_2$ > LiOH > $Ca(OH)_2$ > $Mg(OH)_2$. $NH_4OH$, KOH and $Ba(OH)_2$ proved to be efficient hydroxide compounds to use as effective BS reagents in CE instead of NaOH.

• Journal of Powder Materials
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• v.31 no.2
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• pp.126-131
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• 2024

The aim of this study was to improve the chemical stability of cycloserine containing organic and inorganic compounds. Composite particles were manufactured with a 1:1 weight ratio of organic/inorganic compounds and cycloserine. The influence of organic/inorganic compounds on the stability of cycloserine was investigated under accelerated stress conditions at 60℃/75% RH for 24 hours. In addition, the properties of the composite particles were evaluated using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and the dissolution of the drug was assessed by preparing it as a hard capsule. Among the organic and inorganic compounds investigated, calcium hydroxide most improved the stability of cycloserine under accelerated stress conditions (53.3 ± 2.2% vs 1.7 ± 0.2%). DSC results confirmed the compatibility between calcium hydroxide and the cycloserine, and SEM results confirmed that it was evenly distributed around the cycloserine. Calcium hydroxide also showed more than 90% cycloserine dissolution within 15 minutes. Therefore, the calcium hydroxide and cycloserine composite particles may be candidates for cycloserine oral pharmaceuticals with enhanced drug stability.

• Horticultural Science & Technology
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• v.28 no.6
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• pp.1072-1077
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• 2010

Plant diseases including gray mold caused by Botrytis cinerea are often reduced when calcium compounds are used as alternative materials in paprika. However, much less information is available about the effects of calcium compounds on controlling of $B.$ $cinerea$. Seven calcium compounds such as calcium sulfate dihydrate, calcium chloride, calcium nitrate, calcium oxide, calcium hydroxide, calcium carbonate, and calcium hydride were evaluated for their effectiveness against $B.$ $cinerea$ on potato dextrose agar medium. The pH of selected calcium compounds was higher (pH 8.2-10) than that of the control (pH 6.6). Calcium carbonate, calcium oxide, calcium hydride, and calcium hydroxide among seven calcium compounds were more effectively inhibited the growth of $B.$ $cinerea$ than other calcium compounds. In the case of spraying the spore suspension on paprika applied with the selected four calcium compounds and supplied with the selected calcium supplements in a hydroponic culture system, the paprika treated with calcium compounds showed less severity of disease than those untreated plants. On the basis of our results, we propose that the suppressive effects of calcium compounds on $B.$ $cinerea$ in paprika resulted from the supply of calcium and a certain degree of salt stress.

• Korean Journal of Materials Research
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• v.19 no.5
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• pp.270-275
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• 2009

Lotus-type porous nickel with cylindrical pores was fabricated by unidirectional solidification under an Ar gas atmosphere using the thermal decomposition method of the compounds such as sodium hydroxide, calcium hydroxide, calcium carbonate, and titanium hydride. The decomposed gas does form the pores in liquid nickel, and then, the pores become the cylindrical pores during unidirectional solidification. The decomposed particles from the compounds do play a rule on nucleation sites of the pores. The behavior of pore growth was controlled by atmosphere pressure, which can be explained by Boyle's law. The porosity and pore size decreased with increasing Ar gas pressure when the pores contain hydrogen gas decomposed from calcium and sodium hydroxide and titanium hydride, ; however it they did not change when the pores contain containing carbon dioxide decomposed from calcium carbonate. These results indicate that nickel does not have the solubility of carbon dioxide. Lotus-type porous metals can be easily fabricated by the thermal decomposition method, which is superior to the conventional fabrication method used to pressurized gas atmospheres.

• Environmental Engineering Research
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• v.16 no.3
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• pp.149-157
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• 2011

Nanofiltration (NF) experiments were conducted to investigate fouling of Al-hydroxide precipitate and the influence of organic compound, inorganic compound, and their combination, i.e., multiple foulants. $CaCl_2$ and $MgSO_4$ were employed as surrogates of inorganic compounds while humic acid was used as surrogate of organic compound. The flux attained from NF experiments was fitted with the mathematical fouling model to evaluate the potential fouling mechanisms. Al-hydroxide fouling with a cake formation mechanism had little effect on the NF membrane fouling regardless of the Al concentration. The NF fouling by Al-hydroxide precipitate was deteriorated in presence of inorganic matter. The effect of Mg was more critical in increasing the fouling than Ca. This is because the Mg ions enhanced the resistances of the cake layer accumulated by the Al-hydroxide precipitate on the membrane surfaces. However, the fouling with Mg was dramatically mitigated by adding humic acid. It is interesting to observe that the removal of the conductivity was enhanced to 61.2% in presence of Mg and humic acid from 30.9% with Al-hydroxide alone. The influence of dissolved matter (i.e., colloids) was more negative than particulate matter on the NF fouling for Al-hydroxide precipitate in presence of inorganic and organic matter.

• Bulletin of the Korean Chemical Society
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• v.17 no.6
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• pp.547-550
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• 1996

• Korean Journal of Materials Research
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• v.20 no.12
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• pp.691-698
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• 2010

Magnesium hydroxide-melamine core-shell particles were prepared through the coating of melamine monomer on the surface of magnesium hydroxide in the presence of phosphoric acid. The melamine monomer was dissolved in hot water but recrystallized on the surface of magnesium hydroxide by quenching to room temperature in the presence of phosphoric acid. The core-shell particle was applied to low-density polyethylene/ ethylene vinyl acetate (LDPE/EVA) resin by melt-compounding at $180^{\circ}C$ as flame retardant. The effect of magnesium hydroxide and melamine content has been studied on the flame retardancy of the core-shell particles in LDPE/EVA resin according to the preparation process and purity of magnesium hydroxide. Magnesium hydroxide prepared with sodium hydroxide rather than with ammonia solution revealed higher flame retardancy in core-shell particles with LDPE/EVA resin. At 50 wt% loading of flame retardant, core-shell particles revealed higher flame retardancy compared to that of the exclusive magnesium hydroxide in LDPE/EVA composite, and it was possible to satisfy the V0 grade in the UL-94 vertical test. The synergistic flame retardant effect of magnesium hydroxide and melamine core-shell particles was explained as being due to the endothermic decomposition of magnesium hydroxide and melamine, which was followed by the evolution of water from the magnesium hydroxide and porous char formation due to reactive nitrogen compounds, and carbon dioxide generated from melamine.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.448-452
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• 2001

An Experimental study was carried out to develop a simple method of processing copper waste sludge which is produced by PBC manufacturing. The procedure is based on leaching of wet sludge in 2N H$_2$SO$_4$, and the solid / liquid ratio is controlled approximately at 1/10. The recovery of copper is 85.4%, and pH of the leachate is 3.20. Adding ammonia solution into leachate forms ammine, and hydroxide compounds derived from other impurities in leachate at pH 10. The hydroxide compound can be treated by ferrite process, and the product is a stable oxide compound. Then the ammine solution is heated to evaporate ammonia, and the copper hydroxide is formed. Heating at 8$0^{\circ}C$by aeration, copper hydroxide is transformed into copper oxide with a purity of 98.4%. This process can recover most copper from sludge and the residue can be stabilized by the formation of a stable oxide compound which is not hazardous to environment.

• Resources Recycling
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• v.18 no.2
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• pp.56-61
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• 2009

The dissolution of domestic aluminum hydroxide of 99.7% purity has been performed with mineral and organic acid prior to the synthesis of aluminum compounds from aluminum solution. Mean particle size of aluminum hydroxide used in the work was $14.4{\mu}m$, $22.9{\mu}m$ and $62.3{\mu}m$, respectively and the effect of reaction temperature, concentration of acid and reaction time on the dissolution of aluminum hydroxide has been examined. As a result, the dissolution of aluminum hydroxide was increased with the concentration of HCl and more than 70% dissolution was obtained with 5 mole/l HCl at $70^{\circ}C$ for reaction time of 4 hr. As far as the dissolution of aluminum hydroxide with sulfuric acid was concerned, it was found that the optimum concentration of sulfuric acid was about 6 mole/l for the effective dissolution of aluminum hydroxide. When oxalic acid was used for the dissolution of aluminum hydroxide, nearly complete dissolution could be obtained by the dissolution for 16 hr with 1.0 mole/l oxalic acid at $90^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• v.19 no.10
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• pp.1032-1036
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• 1998

Intercalation compounds of organic anions into layered double hydroxides (LDH) are synthesized by the coprecipitation route. X-ray diffraction data reveal that the intercalated terephthalate (TP), naphthalene-2,6-disulfonate (NA26), and anthraquinone-2,6-disulfonate (AQ26) are arranged with their molecular planes perpendicular to the hydroxide layer. HPLC data show that 26.2% of TP and 73.8% of AQ26 are cointercalated, whereas NA26 is not intercalated into the Zn/Al-LDH. These results indicate the possibility of a molecular recognition ability of Zn/Al-LDH. The molecular recognition ability of intercalation into Zn/Al-LDH is in the order AQ26 > TP >> NA26.