• Korean Journal of Plant Resources
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• v.22 no.3
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• pp.236-241
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• 2009

Dracocephalum argunense Fischer ex Link (Labiatae) is a perennial herbaceous plant used as valuable materials for ornamentals, honey production, and pharmaceutics. Since seed germination of this species was quite difficult, present studies were conducted to improve the germination rate by subjecting the seeds to various environmental conditions (temperature and light) and treatments (scarification, priming and seed coating). Optimum temperature for adequate germination was 20$^{\circ}C$ though it ranged from 15$^{\circ}C$ to 25$^{\circ}C$, and low temperature treatment improved germination rate. Light was required for higher germination rate in this species. The scarification of seeds resulted in much higher germination, especially by the physical treatment with sandpaper or chemical treatment with sulfuric acid for 30 seconds. Various primers with different concentrations were treated on the seeds and it was demonstrated that low temperature enhanced germination rate, regardless of kinds and concentrations of the primers. Three treatment combinations of the primers, 0.5 mM $GA_{3}$ treated for 48 hours, 0.5 mM IAA for 24 hours, and 1.0 mM IAA for 24 hours, increased the seed germination rate profoundly. Soaking treatment of inorganic salts, $KNO_{3}$ and $KH_{3}PO_{4}$, promoted germination when seeds were subjected to low temperature. Water soluble primers such as sucrose at 0.5 and 3% concentration and solid primer talc powder were effective in enhancing germination rate.

• Elastomers and Composites
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• v.51 no.3
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• pp.195-205
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• 2016

A series of aromatic poly(hydroxyamide)s (PHAs) containing varying oligo(oxyethylene) substituents and 1,3-phenylene imide ring unit in the main chain were synthesized by the direct polycondensation reaction. The inherent viscosities of the PHAs exhibited in the range of 0.89~1.12 dL/g in DMAc or DMAc/LiCl solution. The PH-2~5 copolymers were easily soluble in strong aprotic solvents: DMAc, NMP, DMSO etc. and the PH-5 copolymer was soluble in less polar solvents such as m-creasol and pyridine with LiCl salt on heating. However, all PBOs were quite insoluble in other solvents, but only partially soluble in sulfuric acid. All copolymers (PH-2~5) could afford the flexible and tough films by solution casting. We identified that the PHAs were converted to the PBOs by the thermal cyclization reaction in the range of $200{\sim}380^{\circ}C$. The 10% weight loss temperatures and char yields of the PBOs were recorded in the range of $382{\sim}647^{\circ}C$ and 38.7~73.1% values at $900^{\circ}C$. The tensile strength and initial modulus of the PH-5 in the copolmers showed the highest values of 2.46 GPa and 49.55 MPa, respectively. The LOI values of the PHAs were in the range 26.6~29.0%, and increased with increasing 1,3-phenylene imide ring unit.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.247-252
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• 2013

Sulfonated poly(ether ether ketone) (SPEEK) with a certain degree of sulfonation were synthesized by reacting PEEK and sulfuric acid at different reaction time. Then ion-selective composite carbon electrodes (ISCCE) were fabricated by coating the prepared SPEEK on the surface of carbon electrodes. The specific capacitance and resistance of the ISCCE were analyzed by electrical impedance spectroscopy. The ion exchange capacities (IEC) of the SPEEKs were measured in the range of 1.60~2.57 meq/g depending on the sulfonation time. The SPEEK more than 2.5 meq/g of IEC was considered unsuitable for fabricating the ISCCE because it was dissolved in water. The specific capacitance of the prepared ISCCE increased with increasing the IEC of coated SPEEKs and the capacitance was improved up to about 20% compared to that of uncoated carbon electrode. In addition, the electrical resistance of coating layer decreased significantly with increasing the IEC of coated SPEEKs. It is expected that the desalination efficiency of conventional capacitive deionization process can be improved by using the prepared ISCCE coated with SPEEK.

• Korean Journal of Pharmacognosy
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• v.38 no.1
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• pp.56-61
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• 2007

This study was carried out to investigate the optimum conditions for extraction of acidic polysaccharides from red ginseng marc produced by manufacturing alcoholic extract from red ginseng. Method of carbazole-sulfuric acid was applied to determine the amount of acidic polysaccharides in red ginseng marc. The amounts of acidic polysaccharides in water extract of red ginseng marc were increased with increasing extraction temperature. The contents of acidic polysaccharides were not significantly different despite of the extraction time increasing from 6 hours to 48 hours. The contents of starch in water-extract of red ginseng marc were increased with increasing extraction temperature. The starch amounts in water extract of red ginseng marc extracted for 48 hours were increased. The yields of polysaccharide precipitated from water-extract of red ginseng marc were increased with increasing extraction temperature. The hydration rate of acidic polysaccharides and starch from water-extract of red ginseng marc were decreased with increasing extraction temperature. The contents of starch were not significantly different despite of the extraction time increasing from 6 hours to 48 hours at $8^{\circ}C$. However, the rehydration rate of acidic polysaccharide for 48 hours were decreased at $8^{\circ}C$. The rehydration rate of acidic polysaccharide and starch extracted from 6 hours to 24 hours at $25^{\circ}C$ were not significantly different, but those extracted for 48 hours were increased. From the above results, we suggest that by altering the extraction conditions in red ginseng marc it is possible to develop optimum conditions for extraction that modulate the proportions of acidic polysaccharide and starch.

• Journal of Electrochemical Science and Technology
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• v.11 no.1
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• pp.60-67
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• 2020

In this study, copper (II) oxide powder for electroplating was prepared by recovering CuCl₂ from NaClO₃ type etching wastes via recovered non-sintering two step chemical reaction. In case of alkali copper carbonate [mCuCo₃·nCu(OH)₂], first reaction product, CuCo₃ is produced more than Cu(OH)₂ when the reaction molar ratio of sodium carbonate is low, since m is larger than n. As the reaction molar ratio of sodium carbonate increased, m is larger than n and Cu(OH)₂ was produced more than CuCO₃. In the case of m has same values as n, the optimum reaction mole ratio was 1.44 at the reaction temperature of 80℃ based on the theoretical copper content of 57.5 wt. %. The optimum amount of sodium hydroxide was 120 g at 80℃ for production of copper (II) oxide prepared by using basic copper carbonate product of first reaction. At this time, the yield of copper (II) oxide was 96.6 wt.%. Also, the chloride ion concentration was 9.7 mg/L. The properties of produced copper (II) oxide such as mean particle size, dissolution time for sulfuric acid, and repose angle were 19.5 mm, 64 second, and 34.8°, respectively. As a result of the hole filling test, it was found that the copper oxide (II) prepared with 120 g of sodium hydroxide, the optimum amount of basic hydroxide for copper carbonate, has a hole filling of 11.0 mm, which satisfies the general hole filling management range of 15 mm or less.

• BMB Reports
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• v.43 no.11
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• pp.750-755
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• 2010

Crude Orostachys japonicus polysaccharide extract (OJP) was prepared by hot steam extraction. Polysaccharides (OJPI) were separated from OJP by gel filtration chromatography and phenol-sulfuric acid assay. The average molecular weight of the OJPI was 30-50 kDa. The anti-proliferative effect of OJPI on HT-29 human colon cancer cells was investigated via morphology study, cell viability assay, apoptosis assay, cell cycle analysis, and cDNA microarray. OJPI inhibited proliferation and growth of HT29 cells and also stimulated apoptosis in a dose- and time-dependent manner. In cell cycle analysis, treatment with OJPI resulted in a marked increase of cells in the G0 (sub G1) and G2/M phases. To screen for genes involved in the induction of cell cycle arrest and apoptosis, the gene expression profiles of HT-29 cells treated with OJPI were examined by cDNA microarray, revealing that a number of genes were up- or down-regulated by OJPI. Whereas several genes involved in anti-apoptosis, cell proliferation and growth, and cell cycle regulation were down-regulated, expression levels of several genes involved in apoptosis, tumor suppression, and other signal transduction events were up-regulated. These results suggest that OJPI inhibits the growth of HT-29 human colon cancer cells by various apoptosis-aiding activities as well as apoptosis itself. Therefore, OJPI deserve further development as an effective agent exhibiting anticancer activity.

• Journal of the Mineralogical Society of Korea
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• v.29 no.3
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• pp.113-122
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• 2016

This study aims to improve the recovery of gold and silver by removing hematite from gold ore of an oxidation zone with ammonia solution. Quartz, hematite and muscovite were present in the oxidation zone, while hematite was hydrogenous. As a result of performing an ammonia leaching test on variables, it is found that the maximum Fe leaching parameter was $-45{\mu}m$ particle size, 1.0 M sulfuric acid concentration, 5.0 g/l ammonium sulfate concentration and 2.0 M hydrogen peroxide concentration. It is also confirmed that goethite was precipitated and formed from that ammonia elution. As the amount of Fe-removal was increased in a solid-residue, the recovery of Au and Ag were increased, too.

• Resources Recycling
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• v.23 no.5
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• pp.21-27
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• 2014

A study on the solvent extraction for the recovery of Li from lithium-containing waste solution was investigated using $D_2EHPA$ as an extractant. The experimental parameters, such as the pH of the aqueous solution, concentration of extractant and phase ratio were observed. Experimental results showed that the extraction percentage of Li was increased with increasing the equilibrium pH. More than 50% of Li was extracted in eq. pH 6.0 by 20% $D_2EHPA$. From the analysis of McCabe-Thiele diagram, 95% of Li was extracted by four extraction stage at phase ratio(O/A) of 3.0. Stripping of Li from the loaded organic phases can be accomplished by sulfuric acid as a stripping reagent and 90 ~ 120 g/L of $H_2SO_4$ was effective for the stripping of Li. Finially, Li was concentrated about 11.85 g/L by continuous stripping process, and then lithium carbonate was prepared by precipitation method.

• Journal of the Korean Chemical Society
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• v.35 no.5
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• pp.534-538
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• 1991

A procedure for spectrophotometric determination of traces of boron in high-purity trichlorosilane (TCS) is proposed utilizing an adsorptive separation. NaCl is chosen as an Lewis base adsorbent which forms a complex with boron compounds in TCS, and is well dissolved in sulfuric acid-quinalizarin color-forming agent without causing an interference in colorimetric measurements. The proposed adsorptive separation method is free from the formation of silica gel and gas bubbles during the analysis of TCS. The method reveals that the boron concentration in a semiconductor grade TCS is 6.1 ${\mu}$g/l within the standard deviation of ${\pm}$20%. On the other hand, the boron concentration of the purified TCS which is separated from NaCl-boron compounds complex is reduced to 0.2 ${\mu}$g/l, showing the efficient applicability of NaCl to the adsorptive separation. The effectiveness of NaCl for the removal of boron in TCS purification is also described in comparison with other well-known adsorbents.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.1
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• pp.47-53
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• 2012

As one of the methods for recycling the FRP from the waste ships, separation of roving layer from the mat has some merits in a sense of the eco-friendly and economical recycling process. Similar characteristics, however, between the roving and the mat even with different ratio of the resin and the glass and the thickness of the roving, much thinner than the mat, make the mechanically automatic differentiation difficult. In this study spectrochemical differentiation between the two layers has been made using boiling concentrated sulfuric acid, methanol and isopropanol solution saturated with KOH, or hydrogen fluoride (HF) solution. Furthermore efficiently coloring water-soluble dye following the HF treatment makes the roving layer more distinguishable photophysically. The layer differentiation and the automatic layer distraction move up the date of simple and automatic separation process for the waste FRP.