• KSBB Journal
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• v.8 no.3
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• pp.209-216
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• 1993

For the production of biodegradable polymers from microorganisms a bacterial strain producing a biopolymer was isolated from soil. The bacteriological characteristics of this strain and physicochemical Properties of the biopolymer produced were investigated. The bacterial strain was identified as an alkalophilic Alcaligenes sp. The Purified biopolymer treated with cetylpridinium chloride and acetone was identified as an acidic biopolymer having carboxyl groups and showed strong UV absorbance (at 210nm). The biopolymer was composed of 100% glutamic acid and glutamic acid existed as $\gamma$-polyglutamic acid($\gamma$-PGA) in the form of the $\gamma$-peptide bond. The equivalent weight of this $\gamma$-PGA was estimated about 350, indicating that one acidic fraction per 2.7 residue of $\gamma$-polyglutamic acid existed. The molecular weight was $6.5{\times}10^5$ Daltons.

• YAKHAK HOEJI
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• v.33 no.5
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• pp.280-284
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• 1989

When 2,6-Dimethyl-4-(3'-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-mono methyl ester(3) was reacted with dimethyl methylene ammonium chloride (5a) and $K_2CO_3$ in DMF, 2,6-dimethyl-4-(3'-nitrophenyl)-5-(N,N-dimethylamino)methyl-1,4-dihydropyridine-3-carboxylic acid methyl ester (6a) was obtained in 41% yield. As the same procedure with compound (3) and the other dialkylaminomethylating reagents (5b, c, d, e), 2,6-dimethyl-4-(3'-nitrophenyl)-5-(N,N-diethylamino)methyl-1,4-dihydropyridine-3-carboxylic acid methylester(6b), 2,6-dimethyl-4-(3'-nitrophenyl)-5-(1'-pyrrolidinyl)methyl-1,4-dihydropyridine-3-carboxylic acid methyl ester (6c), 2,6-dimethyl-4-(3'-nitrophenyl)-5-(1'-piperidinyl)methyl-1,4-dihydropyridine-3-carboxylic acid methyl ester (6d) and 2,6-dimethyl-4-(3'-nitrophenyl)-5-(1'-morpholinyl)methyl-1,4-dihydropyridine-3-carboxylic acid methyl ester (6e) were obtained in 28%, 49%, 48% and 18% yield respectively.

• Korean Chemical Engineering Research
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• v.58 no.2
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• pp.293-300
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• 2020

Eucheuma spinosum, red macro-algae, contains carrageenan as the major polysaccharide and is commercially produced in Indonesia, Malaysia, Philippines, China and Tanzania. In this study, E. spinosum was converted to sugar and platform chemicals (5-HMF, levulinic acid, formic acid) via FeCl₃-catalytic hydrothermal reaction. In addition, statistical methodology (3-level 3-factor Box-Behnken design) was applied to optimize and evaluate the effects of reaction factors (reaction temperature, catalyst concentration and reaction time). As a result of optimization, the concentration of 5-HMF was obtained to be 2.96 g/L at 160 ℃, 0.4 M FeCl₃ and 10 min. Optimal conditions of levulinic and formic acids were determined at 200 ℃, 0.6 M FeCl₃ and 30 min, and the concentrations were obtained to be 4.26 g/L and 3.77 g/L, respectively.

• Journal of the Korean institute of surface engineering
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• v.37 no.2
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• pp.110-118
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• 2004

The corrosion of pure titanium (CP- Ti Grade 2) and titanium alloy (Ti6Al4V ELI) were studied under various conditions of simulated body fluids. The static immersion test and the electrochemical test were performed in accordance with ISO 10271 : 2001. For the electrochemical test, the open circuit potential was monitored as a function of time, and the cyclic polarization curve was recorded. The corrosion resistance was evaluated from the values of corrosion potential, passivation current density, breakdown potential, and the shape of hysteresis etc. The effects of alloy type, surface condition, temperature, oxygen, and constituents in the fluids such as acid, chloride were estimated. Both specimens had extremely low dissolution rate in the static immersion test. They showed strong passivation characteristics in the electrochemical test. They maintained negligible current density throughout the wide anodic potential range. The passive layer was not broken up to 2.0 V (vs. SCE). The hysteresis and the shift of passivation potential toward the anodic direction was observed during the reversed scan. The passivation process appeared to be accelerated by oxygen in air or that dissolved in the fluids. The passivation also proceeded without oxygen by the reaction of constituents in the fluids. Acid or chloride in the fluids, specially later weakened the passive layer, and then induced higher passivation current density and less shift of passivation potential in the reversed scan. CP-Ti Grade 2 was more reactive than Ti6Al4V ELI in the fluids containing acid or chloride, but thicker layer produced on its surface provided higher corrosion resistance.

• Resources Recycling
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• v.17 no.2
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• pp.70-75
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• 2008

A study on the cementation for the recovery of tin with aluminium in the hydrochloric acid solution was carried out. Parameters, such as aluminium metal equivalent, pH, reaction time, reaction temperature and the concentration of chloride ions were investigated. The experimental results showed that the cementation rate of Sn(II) ions increased with increase of the addition amount of aluminium powders, temperature, pH and the concentration of chloride ions in hydrochloric acid solution. From the results, the optinum conditions for recovery of metallic tin by cementation with aluminium metal powders were proposed.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2001.11a
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• pp.114-114
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• 2001

Since hypoxia-inducible factor-lalpha (HIF-lalpha) and the arylhydrocarbon receptor (AhR) shared the AhR nuclear translocator (Arnt) for hypoxia- and AhR-mediated signaling, respectively, it was possible to establish the hypothesis that hypoxia could regulate Cyplal expression. In order to understand the mechanism of Cyplal gene expression, we demonstrated here that hypoxic agents such as cobalt chloride, desferrioxarnine, and picolinic acid reduced the TCDD induced Cyplal promoter activity based on the determination of luciferase activity in Hepa I cells transfected with pmCypla1-Luc. Also cobalt chloride inhibited the TCDD stimulated Cyplal mRNA level as well as EROD activities in both Hepa I and MCF-7 cells. Hypoxic agents such as cobalt chloride, picolinic acid, and desferrioxamine showed inhibition of luciferase activity that was induced by lnM TCDD treatment with dose dependent manner. Concomitant treatment of 150${\mu}$M ferrous sulfate with 1∼100${\mu}$M desferrioxarnine or 1∼100${\mu}$M picolinic acid recovered from the hypoxic agents-inhibited luciferase activity that was stimulated by TCDD. Reciprocally, the hypoxic agents down regulated TCDD induced Cyplal mRNA level and CYP1A1 enzyme activity in Hepa I cells.

• Resources Recycling
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• v.15 no.5 s.73
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• pp.52-56
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• 2006

Waste aluminum dross was leached with hydrochloric acid to prepare PAC, poly aluminium chloride, used as water treatment chemicals. Metallic aluminum remained in the waste aluminum dross was dissolved into the hydrochloric acid solution. The solution could be used as PAC after adjusting the required alumina concentration and the basicity. Comparing to the conventional method far preparation of PAC using aluminum hydroxide, material cost could be saved in this method. Also, there is an additional merit in view of recycling of the waste aluminum dross by reducing the amount of waste dross to be landfilled.

• Journal of the Korean Applied Science and Technology
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• v.7 no.2
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• pp.11-18
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• 1990

N-alkyl carboxy pyridinium chlorides such as N-lauryl carboxy-pyridinium chloride, N-myristyl carboxy pyridinium chloride, N-cetyl carboxy pyridinium chloride and N-stearyl carboxy pyridinium chloride were synthesized by the reaction of nicotinic acid and isonicotinic acid with long chain alkyl chlorides, and N-alkyl pyrinium carboxylates such as N-lauryl pyridinium carboxylate, N-myristyl pyridinium carboxylate. N-cetyl pyridinium carboxylate and N-stearyl pyridinium carboxylate were prepared from N-alkyl carboxy pyridinium chlorides. These reaction products could be separated by both column chromatogrphy, and paper chromatography, and there dissociation constants of N-alkyl pyridinium carboxylates were found to pKa $1.0{\times}10^{13}{\sim}6,31{\times}10^{14}$.

• Journal of Environmental Science International
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• v.23 no.6
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• pp.1157-1163
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• 2014

The solid phase extractant (PVC-D2EHPA bead) was prepared by immobilizing di-2-ethylhexyl-phosphoric acid (D2EHPA) with polyvinyl chloride (PVC). The prepared PVC-D2EHPA beads were characterized by using fourier transform infrared spectrometer (FTIR) and scanning electron microscopy (SEM). The removal experiments of Cu(II) by PVC-D2EHPA beads conducted batchwise. The removal kinetics of Cu(II) was found to follow the pseudo-second-order model. The equilibrium data fitted well with Langmuir isotherm model and the maximum removal capacity was 2.6 mg/g at $20^{\circ}C$. The optimum pH region was in the range of 3.5 to 6. and the standard free energy (${\Delta}G^{\circ}$) was between -4.67~-4.98 kJ/mol, indicating the spontaneous nature of Cu(II) removal by PVC-D2EHPA beads.

• Journal of the Korean Applied Science and Technology
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• v.14 no.2
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• pp.93-102
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• 1997

Isothiazoline derivatives is widely used to food, medical drug and industrial goods, cosmetics etcs, and it makes to restrain and to sterilize a breeding of microbe as a preservative and a sterilizing agent. It differs with the raw material of paraoxybenzoic acid derivatives or imidazolydinyl urea to be in use at present, on the efficacy and effect, and has various characteristics. This synthesis makes 3,3'-dithiodipropionic chloride to add a thionyl chloride in 3,3'-dithiodipropionic acid, and 3,3'-dithiodipropionic methyl amide makes to synthesize in a reflux reaction the mono methyl amine to 3,3'-dithiodipropionic chloride. And last synthesis becomes to make chlorination-cyclization molecule doing a reflux reaction in the temperature of $90{\sim}100^{\circ}C$ to mix excessively thionyl chloride and ethylene dichloride to 3,3'-dithiodipropionic methyl amide. The last synthesis material has got in the mixture of 5-chloro-2-methyl-4-isothiazoline-3-one and 2-methyl-4-isothiazoline-3-one, and it is so-called isothiazoline derivatives. The purification of isothiazoline derivatives makes to fuse in ethyl acetate, and makes to decolorize and to deodorize in recrystallization. This experiment has been in synthesis and purification of isothiazoline derivatives, and has tried to measure on the antisepsis and sterilization function of microbe according to pH or content change.